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  • 1.
    Ahlström, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    Online-instrumentering på avloppsreningsverk: status idag och effekter av givarfel på reningsprocessen2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The effectiveness of automated treatment processes within wastewater treatment plants ultimately depend on the quality of the measurement data that is given from the installed sensors. Sensor faults affect the control of the treatment plants and are often the reason different control strategies fail. Today there is a lack of standardized guidelines for how to organize and work with online sensors at Swedish wastewater treatment plants which limits the opportunities for treatment plants to reach their effluent criteria in a resource efficient manner. Much research has been done on ways to optimize control strategies but the role of sensors in the efficiency of the treatment plants has not been given the same level of attention. The purpose of this thesis has been to examine how instrumentation at wastewater treatment plants can be organized and structured to ensure good quality measurement data and to examine how sensor faults affect the treatment process.

    Within the thesis a literature study was conducted where instrumentation at wastewater treatment plants was examined. The effects of sensor faults were examined by simulating a pre-denitrification process in Benchmark Simulation Model no. 2 where off-sets (biases) and drift where added to measurements from different implemented sensors. The simulations showed that positive off-sets (0.10–0.50 mg/l) in an ammonium sensor within a cascaded feedback-loop adds to the energy consumption used for aeration by roughly 4-25%. It could further be shown that all types of faults in a DO sensor in the last aerated basin had significantly larger effect on the treatment process than the same fault in any of the other DO sensors in the preceding basins. If the last aerated basin is designed to have low DO concentrations the DO sensor in that basin is the most important DO sensor to maintain. Positive off-sets (200–1 000 mg TSS/l) in suspended solids sensors used for control of waste activated sludge flow contributed to large increases of ammonia, by 29-464%, in effluent waters. Negative drift in DO sensors showed that significant savings in aeration energy, roughly 4%, was possible to achieve with more frequent maintenance.

    Whether a sensor is affected by a positive or a negative fault, be it off-set or drift, will affect how much and in what way the treatment process will be affected. The study of sensor faults showed that the effect of a positive or a negative fault varied and that the effect on the treatment process was not linear. The effect of a sensor fault on the treatment process will ultimately depend on the implemented control strategy, settings in the controllers and on the controlled process.

  • 2.
    Alessandro, Martini
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    Biosensorsystem för övervakning av vattenkvalitet2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sweden's drinking water quality is considered to be high partly due to a high quality of the raw water and a well developed sewage infrastructure. Despite this, there is water contamination that could be prevented by installation of a sophisticated early warning system. Some of the major players in the production of drinking water have already invested in different types of early warning systems to ensure drinking water of high quality. There are various forms of early warning systems where automatic monitoring of E. Coli is an interesting alternative. Today's technology allows for this type of measurement, but it is often expensive and sometimes slow.

    This work aims to investigate whether the phenomenon of Extraordinary Optical Transmission (EOT) can be used as the technology of sensors for real-time measurement of indicators of fecal contaminated water. EOT is a transmissions peak which arises due to plasmon resonance. The study was conducted by performing verification measurements by spectrophotometry to detect the EOT. After this biomeasurements where done to show that the surface of the sample can be functionalized to provide the opportunity to choose which analytes should be detected.

    The verifying measurements showed that EOT was detected for one of the five samples where the hole size was 400 nm and the hole spacing was 600 nm. This is due to the high signal strength and to the fact that the phenomenon occurred within the measurement range of the instruments. Samples where designated with the name sPa where s indicates hole size in nm and a hole spacing in nm. The signal strength of the sample 140P600 and 200P600 was too low to determine whether EOT occurred. For samples 400P1000 and 600P1000 calculations showed that EOT occurred outside the measurement range, which meant that EOT could not be measured. Sample 400P600 was chosen to implement bio-measurements wherein the surface was functionalized with biotin Bovine serum albumin (B-BSA) to later bind with fluidMAG Streptavidin. Both B-BSA and streptavidin was bound as shown by the kinetic measurements. 

  • 3.
    Ambjörnsson, Linn
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Ewald, Katti
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Johansson Kling, Erika
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Larsson, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Marie, Selenius
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Elin, Svedberg
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Purification of arsenic contaminated water using ferrihydrite with consideration to current circumstances in Burkina Faso2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Ferrihydrite in a suspension has been studied as a solution for purification of arsenic contaminated water. Many development countries, amongst them Burkina Faso, have arsenic in their groundwater and the current methods for purification are too expensive. Measurements have shown extremely high levels of arsenic in the groundwater in several places in Burkina Faso. Since the availability of surface water is limited, the groundwater is still used as drinking water.

     

    A suspension of ferrihydrite has capacity to adsorb arsenic in water due to its chemical characteristics. Small-scale laboratory work with ferrihydrite suspensions has been performed in parallel in Uppsala, Sweden, and Ouagadougou, Burkina Faso. To purify the water with regard to the economical and practical circumstances in Burkina Faso, a column with safety filter was made out of simple materials such as plastic bottles, plastic tubes and glass wool. The contaminated water was flowing upwards through the column to prevent the filter from clogging.

     

    In Uppsala it was discovered that a 1 L ferrihydrite suspension containing 10 g ferrihydrite can adsorb 0.7 g arsenic while it was shaken and centrifuged well. In Ouagadougou it was possible, in the setup, to clean 2 L arsenic contaminated water with the concentration of 100 µg/L. The conclusions from the experiments in this project are that ferrihydrite can adsorb arsenic in contaminated water but that the setup used needs to be further evaluated and developed

  • 4.
    Andersson, Johanna
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Optimering av driftstemperatur vid mesofil rötning av slam: - funktionskontroll vid Uppsalas reningsverk2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Energy efficient processes and the use of fossil free fuels play an important role in order to reduce the impact of climate change. Anaerobic digestion is a common way for stabilizing sewage sludge at wastewater treatment plants (WWTP). One of the benefits with anaerobic digestion is that it also produces biogas, a fossil free fuel with low greenhouse gas emissions. An operational temperature within the mesophilic range has proven to give a stable process with an unfluctuating production of gas. The mesophilic temperature range between 25-40°C but most processes are operated between 35-40°C. This study investigates the opportunity to lower the temperature within the mesophilic range in order to reduce energy consumption. It is important to maintain the production of biogas with a lower temperature. Therefore, the reduction in VS-content (VS-volatile solids), methane yield and time for degradation was determined by a BMP-experiment (BMP-Biochemical Methane Potential) in three different temperatures (32, 34.5 and 37.5°C). In order to quantify the reduction in heat consumption with lower operational temperatures the change in heat balance for a full-scale WWTP in Uppsala was calculated. A major part of the operational cost is dewatering of sludge and it is therefore important that it does not deteriorate with a lower temperature. The effect on the dewaterability at different temperatures was examined by a filterability test measuring CST (capillary suction time). The results from the study showed no significant difference in methane yield between 37.5°C and 34.5°C. The methane yield at 32°C was 11 % lower compared to 37.5°C but the degradation kinetic was not affected by a temperature change. The reduction in heat consumption was 14 % when the temperature was reduced to 34.5°C and 27 % when it was reduced to 32°C. The filterability test did not show a deterioration with lower temperatures. The study showed that it is possible to reduce the operational temperature for anaerobic digestion at the WWTP in Uppsala in order to reduce the energy consumption. To confirm these results a continuously experiment should be done, but this study shows that it is possible to get a successful degradation in a lower mesophilic temperature. This leads the way for further investigations within the mesophilic range and could lead to optimizing anaerobic digestion and the opportunity to get an energy efficient production of biogas.

  • 5.
    Asplund, Malin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Mark- växtsystem för behandling av lakvatten: utvärdering av reningseffekter vid Häradsuddens deponi2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    En av de viktigaste miljöaspekterna när det gäller deponering av avfall är utsläpp till vatten. Tidigare leddes lakvatten från de flesta deponier till kommunala reningsverk, men på senare tid har trenden gått mot allt mer lokala lösningar i mark- växtbaserade system.

    Vid Häradsuddens deponi i Norrköpings kommun har Econova mellan åren 2007 och 2011, i etapper, anlagt ett kombinerat system med lakvattenrecirkulering, luftad damm, intermittent översilning samt våtmark för rening av lakvattnet. Syftet med denna studie var att klarlägga vattenbalans och reningsfunktion för Häradsuddens reningssystem samt ge förslag på eventuella förbättringar.

    Resultaten i undersökningen tyder på en avsevärt högre belastning på våtmarken än de kända flöden som pumpas till lakvattensystemet, vilket tyder på utläckage av lakvatten från deponin. Reningssystemet klarade dock med god marginal reningskraven avseende halt för NH4-N och Ptot. Begränsande för möjligheten att släppa vattnet till recipient är halten TOC. Med anledning av lakvattnets sammansättning samt de förhållandevis höga halterna i tillrinnande vatten kan det bli svårt att komma ner i TOC-halter som säkrar möjlighet till utsläpp av behandlat lakvatten.

    Den areaspecifika reningen varierade beroende på om hänsyn togs till förmodat inläckage. Den areaspecifika reningen avseende NH4-N och Ntot var i princip obefintlig om ingen hänsyn togs till inläckage av lakvatten medan den var 80 respektive 50 g/m2·år om en beräkning av möjligt inläckage räknades med. När det gäller Ptot ökade avskiljningen från 1 till 2 g/m2·år vid hänsyn tagen till inläckage. Avskiljningen var något låg jämfört med etablerade våtmarker, men borde kunna öka med tiden.

    Analysunderlag för den luftade lakvattendammen och översilningen är otillräckligt och osäkert för att det ska kunna gå att dra några långtgående slutsatser avseende reningseffekt för dessa delar. De bedöms dock kunna ha potential för att öka avskiljningen, varför en noggrann utredning av reningseffekt och olika driftstrategier för lakvattendammen och översilningen rekommenderas.

  • 6.
    Bercoff, Alexandra
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    Investigation of the treatment process at Kungsberget's wastewater treatment plant under periods of irregular and low loads2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    At Kungsberget ski-resort in Gävleborg county all wastewater produced at the facility is treated on-site. The treatment takes place at their own wastewater treatment plant in a so-called Sequence Batch Reactor (SBR), which has been in operation for about a year before this study. Kungsberget AB is currently in charge of the facility but their goal is to hand responsibility over to Sandviken Energy AB. In order for this handover to occur Kungsberget has to produce three approved treatment results. This means that the concentrations of BOD7 needs to lie under 0.3 mg/l and total phosphorous under 10 mg/l in the effluent water for three consecutive samples. The results show momentaneous values. These limits are stated in the permit Kungsberget received from the Environmental Protection Division. Kungsberget has had problems with high and fluctuating phosphorous concentrations and therefore the transfer has not yet taken place.

    In this project several parameters have been analysed in order to obtain an overview of prevailing influent and effluent concentrations. Some of the parameters that have been analysed are; phosphorous, nitrogen, BOD7, suspended solids and pH. A lot of time and effort has been put into elucidating operational routines at the wastewater treatment plant (WWTP) and gaining knowledge from available literature regarding different parameters’ effect on treatment results.  

    Kungsberget has had problems adapting operating routines and reaching stable treatment results as the load is highly effected of seasonal fluctuation. This has not been taken into account earlier and the WWTP has been operated in the same manner all year around. Suggestions to how operating routines can be modified in to better meeting the needs have been produced and alternative treatment methods have been presented in the report. Two of the suggestions include biological phosphorous removal and adding carrier media to increase bacteria growth.

    An aerobic solids retention time has been calculated in order to evaluate whether nitrifying bacteria have enough time for grow and maintain a stable population. The calculation was carried out by measuring suspended solids and aeration time and the result was a solids retention time of approximately 6 days.

  • 7.
    Bjarne, Katrin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control.
    Optimerad förfällning med hydrolys och fermentation av primärslam för utvinning av kolkälla till efterdenitrifikation.2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Water treatment is costly, from both an economic and environmental point of view, since the need for precipitation chemicals, carbon sources and energy is high. It is therefore desirable to look for alternative solutions that enable plants to be more self-sustaining.

    Hammarby Sjöstadsverket is a pilot plant for wastewater treatment located in Henriksdal, a southeastern neighborhood of Stockholm. The plant is owned by IVL, Svenska Miljöinstitutet and Kungliga Tekniska Högskolan (KTH). Since the pilot plant was built in 2002, several different cleaning techniques have been evaluated with focus on striving for eco-friendly and eco-adapted systems. For instance, a pre-precipitation technique, so-called three step precipitation have been evaluated. The three step precipitation implicates that a metal salt followed by two different polymers are added in the flocculation chamber in the particular order to thereby enable to reduce a higher content of the organic material. In previous precipitation tests at Hammarby Sjöstadsverket, one managed to remove up to 90 % of the organic material using the three step precipitation (IVL, Hammarby Sjöstadsverket, 2011). This can be compared to a removal of only 75 % with ordinary pre-precipitation.

    This thesis aims to validate already obtained results within three step precipitation and with biological hydrolysis of primary sludge, extract a carbon source for post-denitrification containing as high concentrations of Volatile Fatty Acids (VFA) as possible and to investigate the cost of a wastewater treatment plant with three step precipitation, biogas generation and collection of internal carbon source from primary sludge at an upscaling corresponding to 100,000 person equivalents.

    Precipitation experiments were carried out in pilot scale with the precipitation chemicals, PAX-XL 36, combined with a low molecular weight organic polymer, Purfix-120, followed by a high molecular weight inorganic polymer, Super Flock C-494. The purpose of the three step precipitation was to validate the already produced results within three step precipitation and thus separate as large amounts of organic material as possible in the precipitation so that a primary sludge containing a high chemical oxygen demand (COD) can be obtained.Two different dosages of Purfix-120 were tested: 45 and 60 g/m3. The best reduction of COD and phosphorus were obtained when 193 g/m3 PAX XL-36 was combined with 60 g/m3 Purfix-120 and 0.025 g/m3 Super Flock C-494. Hereby a COD reduction of 75 % and a total phosphorus removal of 83 % were obtained.

    By hydrolysis of primary sludge in batch experiments Total Solid (TS) concentrations of 1, 2 and 3 % and residence times of up to eight days were examined. The purpose of the hydrolysis in this case was to investigate which TS concentration and residence time that gave the highest production of VFA. The experiments showed that a TS concentration of 3 % produced the highest amount of VFA and that the VFA production of the three different TS concentrations peaked at the second day. The VFA and COD production increased linearly for the three TS concentrations up until day five. After day five the COD and VFA production, for the TS concentrations of 1 and 2 %, started to decrease slightly. However TS 3 % did not show the same declining trend for VFA. Furthermore the daily ammonium and pH were investigated.  As the VFA and COD concentration increased the ammonium concentration increased as well. pH had overall a  decreasing trend.

    Four different denitrification tests were performed in batch experiments with the extracted hydrolyzate. The added COD content from the hydolyzate was either 3.3 or 4 times the initial nitrate concentration. The denitrification tests showed denitrification rates between 4.3 and 7 mg NO3-N / g volatile suspended solids * h with carbon-nitrogen ratios (C/N ratio) between 3.9 and 12.3 mg COD/mg NO3-N. The lowest C/N ratio received the lowest denitrification rate. However, it could not be concluded that the maximum C/N ratio had the highest denitrification rate.

    Futhermore the financial aspects were examined in order to investigate the cost of a wastewater treatment plant with three step precipitation, biogas generation and collection of internal carbon source from primary sludge at an upscaling corresponding to 100,000 person equivalents. The extraction of an internal carbon source would, despite loss of biogas production, be economically beneficial. Gain, in terms of not having to purchase an external carbon source, in this case ethanol, amounts to the amount of the biogas loss. The three step precipitation chemical costs were the largest item, amounting to 8,060,000 SEK. This cost versus less energy utilization in the biological step was also examined. In this case the savings in the biological step amounted to about 1/8 of precipitation chemical cost. Since the three step precipitation only managed to remove 75 % of the COD, a removal which corresponds to an ordinary pre-precipitation, the three step precipitation is considered to be economically unfavorable as it involves additional costs of polymers. Instead the three step precipitation should be replaced with a pre-precipitation.

    In summary it can be stated that an internal carbon source in the form of hydrolyzed primary sludge could replace an external carbon source in a functional way. However, steps must be taken to minimize the production of ammonium during sludge hydrolysis. From an economic perspective, the extraction of an internal carbon source would only be economical favorable if the three step precipitation is replaced with pre-precipitation.

     

  • 8.
    Bohlin, Ulrika
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control.
    Comparing Cork Filters to Conventional Sand Filters: A Pilot Study of Process Water Treatment2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Process water is used for cooling and for transporting material in all kinds of industries. To clean the water for reuse, various types of filters can be used. Many conventional process water treatment plants incorporate sand filters, which readily clean the water from suspended matters. However, at some circumstances the sand filters do not remove high enough concentrations of metals.

    This master thesis compares the water treatment abilities of activated cork, produced by Spikes & Cogs AB, to those of the sand filters used at steel making company Ovako Hofors AB in Hofors. As an on-site pilot study, the thesis investigates the cleaning capacity of three types of activated cork filters: Fats, Oils and Solvents (FOSS) filter, Fast Acting Digesting Enzymes (FADE) filter, and Metal Adsorption and Concentration (MAAC) filter.

    The cork filters were compared to the sand filters during normal operation and, because of previous problems with the stability of the sand filter performance, during stress tests. The results show that the cleaning capacity of the sand filters is higher than the cleaning capacity of the cork filters at normal operation. At the conditions of the stress tests, at which the sand filters do not function, the cleaning capacity of the cork filters was somewhat lowered but was still well within acceptable limits.

    An important result from the experiments is that the cork filters neutralize the pH. The sand filters are sensitive to changes in the pH, meaning that the cork filters could function as a buffering unit prior to the sand filters.

  • 9.
    Carlsson, Bengt
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Diehl, Stefan
    Zambrano, Jesús
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Analyses of Activated Sludge Processes Consisting of a Plug-Flow Reactor and a Non-ideal Settler2015In: Proc. 9th IWA Symposium on Systems Analysis and Integrated Assessment, 2015Conference paper (Other academic)
    Abstract [en]

    An activated sludge process (ASP) consisting of a plug-flow reactor (PFR) and a non-ideal settler is modelled and analysed. One soluble substrate component and one particulate biomass are assumed. The biomass growth rate is described by a Monod function. The settler model includes hindered settling and compression. A model describing the steady-state behaviour of the ASP is derived which constrains the settler to work with a fixed sludge blanket height in the thickening zone. The model provides new understanding for these types of ASPs and may be used for novel design schemes. The numerical example suggests that the steady-state solutions of the ASP give a one-parameter family of solutions, where the parameter is the recycle ratio r.

  • 10.
    Carlsson, Bengt
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Zambrano, Jesús
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Analysis of simple bioreactor models: A comparison between Monod and Contois kinetics2014In: Proc. IWA Conference on Activated Sludge – 100 Years and Counting, IWA Publishing, 2014Conference paper (Refereed)
    Abstract [en]

    In this paper, an analysis of simple bioreactors in series is presented. The bioreactors are analysed for growth kinetics of the biomass described by a Monod and a Contois function. In particular, it is studied how the effluent substrate concentration is depending on the influent substrate concentration during steady state. It is shown that by going from one to two bioreactors in series completely changes the process behaviour when the growth kinetics is described by a Monod function. It is also shown that a bioreactor described by Contois kinetics has a completely different behaviour compared with the Monod case.

  • 11.
    Carlsson, Bengt
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Zambrano, Jesús
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Fault detection and isolation of sensors in aeration control systems2016In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 73, no 3, p. 648-653Article in journal (Refereed)
    Abstract [en]

    In this paper, we consider the problem of fault detection (FD) and isolation in the aeration system of an activated sludge process. For this study, the dissolved oxygen in each aerated zone is assumed to be controlled automatically. As the basis for an FD method we use the ratio of air flow rates into different zones. The method is evaluated in two scenarios: using the Benchmark Simulation Model no. 1 (BSM1) by Monte Carlo simulations and using data from a wastewater treatment plant. The FD method shows good results for a correct and early FD and isolation.

  • 12.
    Carlsson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Kartläggning av upphandlingsprocessen inom vatten- och avloppsbranschen – användning av livscykelkostnader i processen2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of public procurement is to create competitive markets and generate the bestpossible deal for the contracting authority. Public procurement should aim for long-termperspective, and there are tools to ensure that a long-term view is obtained. One tool is lifecycle costs (LCC), where product acquisition, ownership and settlement are considered. Aproduct that has a high investment cost but low operating costs, may be the most costeffectivepurchase. LCC is used to achieve an economic evaluation of different investmentoptions, discounted over the lifetime of the product. Life-cycle costing is an approach thatexplores the various investment options and is used to as a basis of discussion by theparticipants in the procurement process.

    The use of life-cycle costs, are expected to be useful for decision makers in the water andwastewater industry if they want to take long-term correct decisions. The problem is that noone has studied how a life cycle cost tool affects the decision-making process in publicprocurement within the water and wastewater industry and if it gives the client a gooddecision making basis. This study therefore aimed to find out how life cycle costs are used inpractice and how these can be used in practice, as an aid in the decision making process forwater and wastewater procurements. The study also aimed to find out how a life cycle costtool should be designed, by giving suggestions on conditions that must be taken into account.

    This thesis has been carried out on behalf of The meeting place for the industry in watertreatment (VARIM), with the aim to investigate the procurement process within the water andwastewater trade. It also studies how life cycle costs are used in the process. The study wascarried out in two steps, consisting of qualitative interviews, 27 individual interviews gaverise to a rich material, which was subject to further analysis. The interviewees had fivedifferent roles in the procurement process: client, purchaser, user, consultant and bidder. Thestudy was limited to investigating four types of municipalities: large cities, major cities,manufacturing municipalities and rural municipalities. The results from the interviews wereanalyzed based on theory from the literature study, the results from the data collection wereanalyzed.

    The results show that life-cycle costs in water and wastewater procurement are needed. Thereis also great potential for LCC as the majority of respondents were in favor of the use of LCC,primarily in the procurement of energy-using products or processes. A great difference inaccess to resources was identified between smaller clients and major clients, resulting in thesmaller clients not using life-cycle costs as a criterion. Also the results indicate that the use oflife cycle costs contributes to greater transparency in the procurement process and thereforedecreases risk of appeals. The study shows that follow up of life cycle cost in a contract is oneof the most difficult problems in procurement.

  • 13.
    Carlsson, Ulrika
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Avgång av lustgas från luftningsprocessen på Käppalaverket2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The requirements for wastewater treatment plants (WWTP) are gradually increasing, partly because of higher incoming loads, which in turn require a more efficient treatment process. In parallel with environmental and economic goals there are also desires to lower energy consumption without compromising the wastewater treatment. Furthermore, there is a demand on WWTP´s to alter eutrophication in aquatic systems through better nitrogen and phosphorus removal. An increasing number of WWTP´s have acquired biological nitrogen and phos-phorus removal. A by-product of this type of biological treatment is the formation of nitrous oxide, which is a potent greenhouse gas. But how large is the WWTP´s share of nitrous oxide to the total emissions? To answer this question an increasing number of WWTP´s around the world have begun to study the emission of nitrous oxide. Today it is still not entirely clear where in the process nitrous oxide forms and why. Studies have shown that the emissions are different from different sewage treatment plants, partly because the plants have different loads and treatment processes. It is therefore essential that more studies are made to get a better understanding of the emission mechanism. In the autumn 2011, measurements of nitrous oxide emissions were conducted on Käppala-verket on Lidingö in cooperation with IVL the Swedish Environmental Research Institute. The purpose of the measurements was mainly to get an indication of how much nitrous oxide Käppalaverket emits each year. In addition tests were also conducted on how emissions could be reduced by comparing two different aeration strategies, by keeping different constant levels of oxygen and by using ammonium-feedback. In this latter test correlations between nitrous oxide emissions and various process parameters were studied. The experiments with different control strategies are based on previous American studies that have demonstrated that the oxygen supply of nitrifiers may be crucial for how much nitrous oxide will be emitted. The results of this study show that Käppalaverket´s biological treatment process emits 5.5 tones N2O/year representing 0.3% of the incoming nitrogen. Attempts to compare two different aeration strategies did not fall out as expected due to process disturbances. Collected data have also been analyzed and compared, with focus on causal relationships of nitrous oxide emission. Any clear correlation between nitrous oxide and the studied process changes have not been detected. The study shows that low oxygen levels do not seem to produce more nitrous oxide.

    Keywords: Nitrous oxide, activated sludge process, nitrification, denitrification, greenhouse gas, sewage treatment

  • 14.
    Carlström, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Modellering av organiskt material i avloppsvatten vid mekanisk tillverkning av pappersmassa: Regressionsanalys baserad på COD- och TOC-analyser vid olika grader av blekning och raffinering2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    I avloppsreningen på Hallsta pappersbruk i Hallstavik reduceras dagligen tonvis med organiskt material innan avloppsvattnet släpps ut i den intilliggande Edeboviken. Bruket är ett så kallat integrerat pappersbruk vilket innebär att man tillverkar både pappersmassan och pappret på plats. Det är främst vid framställningen av massa som det organiska materialet löses ut ur veden och hamnar i processvattnet som så småningom når brukets avloppsreningsverk. På bruket tillverkas papper i olika ljusheter, vilket kräver olika stora insatser i form av blekkemikalier så som väteperoxid och hydrosulfit (även känt som ditionit). Blekningen varierar över tid i produktionscykler och det är sedan tidigare känt att en ökad blekning av massan löser ut mer organiska föreningar. I framtiden förväntas andelen högblekta produkter öka, vilket sannolikt leder till ökad belastning på reningsverket. Det finns även planer på att öka andelen papper av sådan kvalitet som kräver att massan raffineras hårdare (så att den blir finare mald) och frågan har lyfts huruvida denna behandling leder till mer organiskt material till avloppet.

    Ökad kunskap om hur flödet av organiskt material till avloppet varierar är då detta skrivs (2012) värdefull i minst två tillämpningar på Hallsta pappersbruk. Den ena tillämpningen är vid utredningen av potentialen för en biogasanläggning på bruket, där det organiska materialet utgör en begränsande resurs vid framställningen av biogas, varför det vore värdefullt att veta hur stora mängder organiskt material som kan förväntas vid olika produktionsfall. Den andra tillämpningen är vid doseringen av kväve och fosfor i reningsanläggningen som görs för att mikroorganismerna som används för att rena vattnet ska kunna arbeta optimalt.

    Huvudsyftet med detta arbete var att skapa en modell för hur mängden organiskt material i olika avloppsströmmar beror på graden av blekning, samt i viss mån raffineringen. Det organiska materialet analyserades som TOC (Total Organic Carbon) och COD (Chemical Oxygen Demand). Ett tydligt samband mellan blekning med väteperoxid och mängden organiskt material i avloppet observerades i en av delströmmarna. Hydrosulfitblekning sågs inte öka mängden organiskt material i avloppsvattnet. En modell för den totala belastningen på avloppsreningsanläggning sattes också ihop, som utifrån planerad dosering av väteperoxid ger en uppskattning av halten TOC i inflödet till anläggningen. Modellen fångar upp den cykliska variation i TOC som observerades över tid, men lämnar lite att önska i fråga om absoluta nivåer.

  • 15.
    Chistiakova, Tatiana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Zambrano, Jesús
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Samuelsson, Oscar
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Binary classifiers applied to detect DO sensor faults during washing events2015In: Proc. 2nd IWA Conference on New Developments in IT & Water, IWA Publishing, 2015Conference paper (Other academic)
    Abstract [en]

    In this paper, several classication techniques are applied for monitoring the status of DO sensors in wastewater treatment plants. In particular, DO sensors during washing events are studied and indication parameters from these events are used. The methods considered are the following: k-Nearest Neighbours, Radial Basis Function and Random Forest classiers. The result shows the comparison and the eligibility of the methods to detect a clogged DO-sensor.

  • 16.
    Chistiakova, Tatiana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Mattsson, Per
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Wigren, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Nonlinear system identification of the dissolved oxygen to effluent ammonia dynamics in an activated sludge process2017Conference paper (Refereed)
  • 17.
    Chistiakova, Tatiana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Mattsson, Per
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Wigren, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Nonlinear system identification of the dissolved oxygen to effluent ammonium dynamics in an activated sludge process2018Report (Other academic)
  • 18.
    Chistiakova, Tatiana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Zambrano, Jesús
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Application of machine learning methods for fault detection in wastewater treatment plants2014In: Reglermöte, 2014Conference paper (Other academic)
  • 19.
    Dahlström, Tove
    Sveriges lantbruksuniversitet, Institutionen för mikrobiologi.
    Nedbrytning av organiskt material och förekomst av svamp- och bakteriesamhällen i Uppsalaåsen2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In Sweden, drinking water is easy to access and often taken for granted. The drinking water systems have to be maintained in order to keep the high quality. The Uppsala esker, which is a part of the Uppsala municipality’s water system, provides a large number of the municipality’s population with drinking water. The Uppsala esker has been used to produce drinking water since 1956 by infiltrating water from the Fyris river into the esker. This reduces the amount of organic material in the water. A reduction is desirable since the organic material is causing odorous water and binds to substances that may harm people’s health.

    The reduction of organic material has been assumed to depend on degradation carried out by microorganisms above the esker’s groundwater table, dilution with additional groundwater and attachment of organic material to the esker’s material. However, recent studies have shown that only 10-15 % of the organic material is degraded above the groundwater table.

    The aim with this master thesis was to examine if the mineralization of the organic material in the anaerobic part of the Uppsala esker is greater than previously assumed. The size of the fungal and bacterial communities have also been examined as well as how microorganisms and the degradation of organic material relates to different chemical and physical factors in the soil.

    To get an understanding of the organic material’s degradability, soil was incubated and the aerobic respiration with gas chromatograph was measured. The bacteria and fungi were quantified using quantitative real-rime PCR. Various chemical and physical factors, such as the content of organic carbon and amount of aluminium, were already available. Pearson’s product-moment correlation coefficient (Pearson's r) was used to examine the the linear correlation between two variables. Wilcoxon’s rank score test was used to determine which of the differences between different sampling areas that were significant.

    The results showed that bacteria dominate in the Uppsala esker and the infiltration basins. Complex binding by iron- and aluminium compounds do not affect the degradation of organic matter, nor decrease the presence of fungi and bacteria in the esker and the infiltration basins. It seems as if the degradation rate’s sensitivity decreases with the depth. The amount of bacteria and fungi decreased with the distance to the infiltration basin, but not the quality of the organic material, if measured by the respiration rate divided by the amount of organic carbon. 

  • 20.
    Danielsson, Lina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Söderberg, Lisa
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Removal of chromium in wastewater with natural clays in southern Malawi2013Student paper other, 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    To live a healthy life, people all around the world need access to safe water. A lot of industries,together with the fast growing population in Blantyre, a city in southern Malawi, pose a threat to theaccess of safe water for the citizens. Several of the industries in Blantyre release contaminated waterto the nearby streams. One serious pollutant emitted from a match factory is chromium (Cr),especially in the occurrence of Cr(VI) which is carcinogenic for humans. Earlier studies have shownthat the concentration of chromium in the match factory’s wastewater was higher than WHO:sguidelines. It has also been published that natural clay minerals can be used for adsorption of Cr(III).This study investigates the removal of Cr(VI) through the adsorption of Cr(VI) to clay minerals or byreduction of Cr(VI) to Cr(III) which is precipitated from solution.The laboratory work performed in this study includes both experiments for adsorption of Cr(VI) andreduction of Cr(VI) to Cr(III). The reducing agents investigated were two clays and Fe(II) sulfate. Foradsorption of negatively charged Cr(VI) compounds, the two clays where used at lower pH and themineral bauxite was also tried as adsorbent agent. Wastewater from the match factory was dilutedand mixed with the removal agents and the concentration of total chromium was measured beforeand after the mixing process. For the agent with highest potential for Cr(VI) removal, the optimalconditions due to pH, dosage of agents and contact time were inspected.None of the investigated reducing agents served its purpose which means that no Cr(VI) was reducedto Cr(III) in this study. The adsorption of Cr(VI) with clay 1 at lower pH was also not successful, butthe adsorption worked for clay 2 at lower pH and for bauxite. In the experiments bauxite adsorbed ahigher amount of Cr(VI) than clay 2. The adsorption with bauxite turned out to be independent interms of pH. The optimal conditions for bauxite in the experiments were with a dosage of 3.5 gbauxite in 50 mL wastewater and a contact time of 40 minutes. The results showed an adsorption of93 percent of total chromium with bauxite at optimal conditions.

  • 21.
    Diehl, Stefan
    et al.
    Lund Univ, Ctr Math Sci, POB 118, S-22100 Lund, Sweden.
    Zambrano, Jesus
    Malardalen Univ, Sch Business Soc & Engn, POB 883, S-72123 Vasteras, Sweden.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Analysis of photobioreactors in series2018In: Mathematical Biosciences, ISSN 0025-5564, E-ISSN 1879-3134, Vol. 306, p. 107-118Article in journal (Refereed)
    Abstract [en]

    A photobioreactor (PBR) contains microalgae which under illumination consume carbon dioxide and substrate dissolved in water, and produce oxygen. The process is used in water recovery resource facilities with a continuous flow of wastewaster through the PBR. With several PBRs in series the reduction of substrate can be improved. This paper contains a thorough analysis of a model of PBRs in series, where each PBR is modelled with a system of three ordinary differential equations for the concentrations of dissolved substrate and biomass (algae), and the internal cell quota of substrate to biomass. Each PBR has a certain volume and irradiation. The absorption rate of substrate into the cells is modelled with Monod kinetics, whereas the biomass growth rate is modelled with Droop kinetics, in which both a minimum and a maximum internal cell quota are assumed. The main result is that the model has a unique stable steady-state solution with algae in all PBRs. Another stable steady-state solution is the wash-out solution with no algae in the system. Other steady-state solutions are combinations of these two with no algae in some of the first PBRs and algae in the rest of the PBRs in the series. Conditions on the illumination, volumetric flow and volumes of the PBRs are given for the respective solution. Numerical solutions illustrate the theoretical results and indicate further properties.

  • 22.
    Diehl, Stefan
    et al.
    Centre for Mathematical Sciences, Lund University, P.O. Box 118, S-221 00 Lund, Sweden.
    Zambrano, Jesús
    School of Business, Society and Engineering, Mälardalen University, Box 883, SE-721 23 Västerås, Sweden.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Steady-state analyses of activated sludge processes with plug-flow reactor2017In: Journal of Environmental Chemical Engineering, ISSN 2160-6544, E-ISSN 2213-3437, Vol. 5, no 1, p. 795-809Article in journal (Refereed)
    Abstract [en]

    Activated sludge processes (ASPs) consisting of a plug-flow reactor (PFR) and a settler are analyzed in steady-state operation using a reduced model consisting of one soluble substrate and one particulate biomass component modelling the dominating biological process. Monod biomass growth rate is assumed. Two settler models are studied. One is the commonly used ideal settler, or point settler, which is assumed to never be overloaded and to have unlimited flux capacity. The other recently published steady-state settler model includes hindered and compressive settling, and models a realistic limiting flux capacity. Generally, the steady-state concentration profiles within the PFR and the settler are governed by nonlinear ordinary differential equations. It is shown that the steady-state behaviour of the ASP can, however, be captured by equations without derivatives. New theoretical results are given, such as conditions by means of inequalities on input variables and parameters for a steady-state solution to exist. Another novel finding is that, if the incoming substrate concentration is increased from a low or moderate stationary value and the solids residence time is kept fixed, then this results in a lower effluent concentration in the new steady state. The steady-state equations are solved numerically for different operating conditions. For common parameter values, numerical solutions reveal that an ASP having a PFR, instead of a continuously stirred tank reactor, is far more efficient in reducing the effluent substrate concentration and this can be obtained for much lower recycle ratios, which reduces the pumping energy considerably.

  • 23. Diehl, Stefan
    et al.
    Zambrano, Jesús
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Steady-state Analysis and Design of Activated Sludge Processes Including Compressive Settling2015In: Proc. 9th IWA Symposium on Systems Analysis and Integrated Assessment, 2015Conference paper (Other academic)
  • 24. Diehl, Stefan
    et al.
    Zambrano, Jesús
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Steady-state analysis of activated sludge processes with a settler model including sludge compression2016In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 88, p. 104-116Article in journal (Refereed)
    Abstract [en]

    A reduced model of a completely stirred-tank bioreactor coupled to a settling tank with recycle is analyzed in its steady states. In the reactor, the concentrations of one dominant particulate biomass and one soluble substrate component are modelled. While the biomass decay rate is assumed to be constant, growth kinetics can depend on both substrate and biomass concentrations, and optionally model substrate inhibition. Compressive and hindered settling phenomena are included using the Bürger-Diehl settler model, which consists of a partial differential equation. Steady-state solutions of this partial differential equation are obtained from an ordinary differential equation, making steady-state analysis of the entire plant difficult. A key result showing that the ordinary differential equation can be replaced with an approximate algebraic equation simplifies model analysis. This algebraic equation takes the location of the sludge-blanket during normal operation into account, allowing for the limiting flux capacity caused by compressive settling to easily be included in the steady-state mass balance equations for the entire plant system. This novel approach grants the possibility of more realistic solutions than other previously published reduced models, comprised of yet simpler settler assumptions. The steady-state concentrations, solids residence time, and the wastage flow ratio are functions of the recycle ratio. Solutions are shown for various growth kinetics; with different values of biomass decay rate, influent volumetric flow, and substrate concentration.

  • 25.
    Elleby, Rasmus
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Användning av anlagd våtmark för efterpolering av rökgaskondensat: en studie vid Brista kraftvärmeverk i Sigtuna2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    At the Brista combined heat and power plant in Sigtuna, wood chips and municipal and industrial waste are incinerated to generate and export electricity and distric heating. When the flue gas is cooled as a part of recycling its energy for distric heating, condensate is formed. Directly after production, the flue gas condensate has a temperature of approximately 30°C and contains relatively high levels of ammonia and certain heavy metals. After treatment inside the plant, the condensate is post-treated in a newly constructed wetland. The main aim of the study was to investigate the nitrogen removal in the wetland but also if current guideline values for effluents established by the environmental court are fulfilled in regard to levels of total and ammonia nitrogen as well as As and heavy metals Cd, Co, Cr, Cu, Hg , Ni, Pb, Tl  and Zn. The study also aimed to measure the wetland area, volume and retention time, investigate differences in water flow between the inlet and outlet as well as study the effect of water temperature on nitrogen removal.

    Water samples were taken weekly for nine weeks in October and November 2014 in the inlet and outlet of the wetland. The samples were analysed for nitrate, nitrite and ammonium ions using ion chromatography. Data from Fortum, the company that runs the heat and power plant, were also used to study levels of nitrogen and metals in the wetland. An optical leveling instrument was used to calculate the wetland volume and GPS was used to calculate its length and area. Measurements of water temperature in the outlet of the wetland were conducted using a logger during a two-month period. Water flow out of the wetland was calculated using water level data from a pump well connected to the outlet.

    The results showed that the levels of the studied compounds in samples collected in this study and by Fortum were all below guideline values. The levels were also low in the flue gas condensate leaving the combined heat and power plant, indicating that the treatment inside the plant is working well. The area of the wetland was measured to 2300 m2 and the volume 940 m3. The calculated water flow out of the wetland was at an average approximately 100 m3/day higher than the inflow, but an error in the calculation model is a possible cause of the difference.

    At low air temperatures, the wetland showed a capacity of cooling significantly higher temperatures of the flue gas condensate than what is usually released from the plant. Because of this, Fortum is recommended to investigate the possibility of reducing the cooling of the flue gas condensate and thus enabling a higher efficiency of temperature dependent treatment processes in the wetland such as nitrogen removal.

  • 26.
    Englund, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Sveriges lantbruksuniversitet .
    Evaluation of the Removal Efficiency of Perfluoroalkyl Substances in Drinking Water2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Per- and polyfluoroalkyl substances (PFASs) are chemicals that have been used for over 50 years. They are both hydrophobic and hydrophilic, which make them useful in a wide range of products, both in the domestic and industrial market. Recently, the global attention on PFASs has increased due to their possible harmful health effects on humans. Furthermore, PFASs have been detected in drinking water sources all over the world. Conventional treatment processes in drinking water treatment plants (DWTPs) are not able to remove PFASs. Therefore, more research is required to find efficient removal techniques for these compounds.

    The aim of this study was to investigate the removal efficiency of PFASs using two different adsorption techniques, anion exchange (AE) with the resin Purolite A-600, and granular activated carbon (GAC) of type Filtrasorb®400. The experiments were performed in laboratory batch-scale, at Swedish University of Agriculture (SLU), and column tests in pilot-scale, at Bäcklösa DWTP in Uppsala.

    The PFASs showed a high sorption potential to AE and GAC. However, the removal efficiency differed depending on the perfluorocarbon chain length, functional group, and concentration level. For the AE, in average 92 % of the PFASs were removed in the end of the batch experiments while the average removal efficiency in the column experiment was 86 %. In the batch experiments treated with GAC on average 55 % of the PFASs were removed in the end of the experiments while the column experiment had the average removal efficiency of 86 %. There was an increase in the removal efficiency with increasing perfluorocarbon chain length in the column experiments. However, in the batch experiments, the adsorption of PFASs decreased with an increasing chain length, except for the highest PFAS concentration level (5000 ng L-1) treated with AE and the lowest PFAS concentration level (200 ng L-1) treated with GAC. In the column experiments, the perfluoroalkane sulfonates (PFSAs) were slightly better removed than perfluoroalkyl carboxylates (PFCAs) with an average removal efficiency of 97 % for AE and 91 % for GAC compared to 67 % and 82 % for AE and GAC, respectively. In the batch experiments, there was no clear trend between the removal efficiency and functional group. Overall, the pilot-scale experiments removed the PFASs relatively well even after 42 days (on average, 86 % for both AE and GAC). The lowest removal capacity in the column experiments was seen for the shorter chained PFSAs (in average 46 % for ≤C6 PFCAs using AE and 75 % for ≤C7 PFCAs using GAC). More efficient treatment techniques are needed to minimise the PFAS concentrations in drinking water and the potential human.

  • 27.
    Forkman, Tova
    Sveriges lantbruksuniversitet.
    Biogaspotential vid samrötningav mikroalger och blandslam från Västerås kommunala reningsverk2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Because of the increasing trends in energy consumption and increased environmental awareness, greater focus has been placed on improvement and development of renewable energy sources. An already proven and accepted method is biogas production from anaerobic digestion at municipal wastewater treatment plants.

    In the waste water treatment process solid material and dissolved pollutants are separated from the water, forming a sludge. The sludge is separated from the process and stabilized during anaerobic digestion or aerobic aeration. Most often, mesophilic anaerobic digestion is used. Because of degradation by microorganisms, biogas with a high content of methane is formed during the digestion. To optimize the process different studies with co-digestion with sludge and other substrate have been made. It has been showed, in earlier research studies, that co-digestion with microalgae and sewage sludge results in a synergistic effect with increased biogas production. As the microalgae are microorganisms which use photosynthesis they contain stored energy from sun light. The stored energy will be available when the microalgae are digested in mesophilic conditions. In contrast to other biomass suitable for co-digestion microalgae have the advantage of being able to grow in waste water and reduce the pollutants in the water phase. Cultivation of microalgae will therefore not compete with the cultivation of food production and at the same time has the possibility to decrease the electricity- and heat consumption at the wastewater treatment plants.

    The aim of this study was to investigate how a possible synergetic effect between microalgae and sewage sludge effects the biogas production and the process stability. The microalgae was cultivated in municipal waste water from the WWTP in Umeå (Sweden) and the sludge was collected from the WWTP in Västerås (Sweden). The fermenters used was of the type DOLLY© and the active volume was 5 dm3. The temperature in the fermenters was kept at 37 °C and the study was divided into two periods. During the first period the hydraulic retention time was 15 days and the organic loading rate 2.4 g VS dm-3 d-1. During the second period the hydraulicretention time was kept at 10 days and the organic loading rate was 3.5 g VS dm-3 d-1.

    The result showed an increase with 54.6 % in methane production per reduced VS in the fermenter with co-digestion compared to the fermenter where only sludge was digested. Period one showed the highest increase. The result also showed a good process stability for both fermenters during the whole experiment.

    This study shows that there are reasons for continued investigations about co-digestion with microalgae and sewage sludge for an increased biogas production.

  • 28.
    Forsberg, Agnes
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Sveriges Lantbruksuniversitet, Institutionen för mark och miljö.
    Utvärdering av två markbaserade dagvattenreningssystem2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Stormwater is a source of pollution to water bodies but can also cause flooding. To treat stomwater locally is an issue of emerging importance due to a changing climate with an increased frequency of heavy rains, but also as a result of more strict guidelines concerning pollution to water bodies. Densification of cities is also a contributing factor. Several methods for sustainable stormwater treatment are used today but the state of knowledge regarding function and capacity is in need of improvement.

    This thesis aimed to evaluate two ground-based stormwater treatment methods, a filter strip and a retention tank. This was done through both literature review and field studies. The field study of the retention tank was limited due to insufficient outflow volumes from the tank. Oil from the filter strip was sampled and analysed for the heavy metals arsenic (As), barium (Ba), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), vanadium (V), and zinc (Zn). According to the study, the filter strip had an elevated concentration of metals in the first 20 meters. Of the total load of heavy metals 20 % of As, 21 % of Cr, 4 % of Cu, 23 % of Ni, 16 % of Pb and 19 % of Zn was retained in the strip. The remaining portion of the heavy metals was assumed to settle in the level spreader before the filter strip or transported past the filter strip. Potential leachability for the metals was analysed with two types of extraction solutions, 1 mM CaCl2 and 0.1 M HNO3. The leaching potential for the studied metals was relatively low, averaging 31% of geochemically active metals. Obtained Kd -values showed the lowest mobility for Pb and Co and the largest mobility for As and Ni. Retrieved mobility for arsenic may be overrated when HNO3 is inefficient for extraction of arsenic. Zinc and cobolt were the limiting metals that can first exceed the limits for sensitive land use; however, this is expected to take place after about 50-60 years.

  • 29.
    Giron, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Effekter på grund- och ytvattenförhållandenkring svenska oljelager i bergrum2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Det saknas i dagsläget en samlad redovisning av erfarenheter rörande påverkan pågrundvattennivåer samt ytvattennivåer och flöden vid grundvattenbortledning från Svenskaberganläggningar. Det saknas även en utvärdering av olika prognosmetoders tillämpbarhetbaserad på prognoser kontra utfall.Det finns ett brett spektrum av metoder för att prognostisera effekterna, från relativt enklabedömningar baserat på vattenbalanser, analytiska lösningar, till avancerade numeriskamodelleringsverktyg. Vilken eller vilka metoder som används i det enskilda fallet styrs idealtav faktorer som exempelvis anläggningstyp, hydrogeologiska förhållanden och dekonsekvenser som grundvattenbortledning potentiellt kan ge upphov till i omgivningen. Ensamling av branscherfarenheter skulle således kunna leda till en effektivisering samt enkostnadssänkning vid framtida bergbyggen.Det saknas även en kartläggning av befintliga berganläggningar i norden. Det finns mängdermed bergrum, tunnlar och gruvor i norden men i dagsläget finns ingen sammanställning avdessa. En sammanställning som redovisar relevant information om området somberganläggningen ligger i som t.ex. berggrund, jordtyp och potentiell grundvattenbildningskulle även det kunna effektivisera arbetet och minska framtida kostnader då en jämförelsesnabbt kan göras med befintliga anläggningar.En analys av ett enklare prognosverktyg som uppskattar uppfyllnadstiden för olikaberganläggningar endast baserat läckvattenmängd och berganläggningens totala volym visadeatt dessa enklare metoder ofta underskattar uppfyllnadstiden.En metod för teoretisk beräkning av påverkansavståd och kvot mellan grundvattenbildning tilljord och berg undersöktes och påvisades gå att använda i områden med tätt berg, dock medstor osäkerhet.

  • 30.
    Guné, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control.
    Källsorterade systems påverkan på avloppsreningsverk: växthusgaser, energi- och resursanvändning i modellstudie2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this study was to evaluate the effects on a simulated wastewater plant regarding GHG emissions and use of energy and resources when implementing source separated wastewater systems. The effects were studied for different restrictions of effluent quality and for different temperatures on the influent. The simulation model BSM2G calibrated for Käppala wastewater treatment plant was used. The task was executed by simulating nine different scenarios with an increase in influent load from new connections equivalent to 3, 10 and 30 % of the present connections. These new connections were served by conventional, urine separated or black water separated systems. All simulations were adjusted to keep the initial effluent load i.e. the effluent load before the number of connections increased. This meant increasing restrictions on effluent load of ammonium and total nitrogen, which were reached by adjusting control parameters such as aeration, internal recycle flow, carbon addition etc. Thus the same effluent load of ammonium and total nitrogen were reached for all scenarios compared to the reference.

    The simulated results showed that the total use of energy (most evident the aeration energy) decreased with 25-60 % with urine separation and with 50-90 % with black water separation compared to corresponding conventional scenario regardless of degree of new connections and contigous adjustment of control parameters. The same tendency applied for use of resources since total operational cost index decreased with 30-70 % with urin separation and 70-90 % with black water separation compared to corresponding conventional scenario regardless of degree of new connections and contigous adjustment of control parameters. Total production of sewage sludge decreased with 5-20 % with urine separation and with 50-60 % with black water separation. Total methane production decreased with 0-20 % with urine separation and with 60-70 % with black water separation. The total GHG emissions from the simulated WWTP was dominated by uncertain N2O emissions from the activated sludge process for all scenarios. Also emissons of N2O due to sludge management were uncertain. Since the production of N2O varied heavily depending on the adjusted control parameters no certain conclusions could be drawn regarding the impact of source separation on these emissions. Other greenhouse gas emissions, such as carbon dioxide emissions due to use of energy, production and degadation of external carbon source were decreased in the source separated scenarios compared to conventional scenarios. The simulated results also showed that a lower temperature of the wastewater led to a decrease in nitrogen removal and an increase in use of energy for all scenarios at 30 % increased influent load compared to a wastewater of average yearly temperature.

    The results confirmed some of the previously stated advantages of source separated wastewater and thus contributed to increased probability of these advantages. However, further studies are needed to obtain more certain results regarding N2O emissions from wastewater treatment plants when source separated wastewater is implemented. 

  • 31.
    Gustafsson, Ida
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Metoder för aktivitetstest av anammox och ammoniakoxiderande bakterier på bärarmaterial2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Given the problem with eutrophication in the Baltic Sea and Sweden's obligations in the Baltic Sea Action Plan, a higher requirement on the removal of nitrogen from the major wastewater treatment plants is expected to be set in the future.

    Anammox is the process where ammonium is oxidized to nitrogen gas with nitrite as electron acceptor. Anammox has been implemented for treatment of the sludge liquor in wastewater treatment plants around the world. When anammox is used to reduce ammonium, the process requires about half the incoming ammonium to be oxidized into nitrite. This is conducted by ammonia oxidizing bacteria (AOB) that require an aerobic environment. The combined process with anammox and nitritation is called deammonification. A pilot study is taking place at Sjölunda Wastewater Treatment Plant in Malmö in collaboration with Water and Environmental Engineering, Department of Chemical Engineering, Lund University. The aim of the pilot study is to explore the potential of implementing deammonification in the main stream at the wastewater treatment plant. The aim of this Master Theisis is to develop methods for activity tests of Anammox and AOB on carrier material. The elaborated methods were then supposed to be used to study the change in activity with decreasing temperature. 

    Since anammox produces nitrogen gas a method based on pressure measurements was developed to determine the anammox activity. The results in this thesis showed that the anammox activity was dependent of the initial concentration of nitrite at concentrations below 75 mg N / L. This dependence is a result of the limitations of the diffusion in the biofilm at low concentrations. When the initial concentration of nitrite was within the range of 75 to 150 mg N / L the activity was independent of the initial concentration. At concentrations above 150 mg N / L there was a decrease in activity which probably occurred as a result of nitrite inhibition.

    To determine the activity of AOB a method based on the oxygen consumption rate was developed. The aeration switched between being turned on and off every five minutes and after some rounds of aereation, ammonium was added. The AOB activity was determined by calculating the difference between the oxygen consumption before and after the addition of ammonium. To ensure that nitrite-oxidizing bacteria (NOB) were not consuming any oxygen, NaClO3 was added at the end of the experiment. The resulting decrease in activity was too excessive to only represent the activity loss from only NOB which may suggest that NaClO3 also inhibits AOB.

    The temperature dependence of anammox activity was analyzed in activity tests at four temperatures in the range of 11.1 to 24.0°C. The experiments concluded that the relationship was exponential and by a drop in temperature from 24.9 ° C to 11.1 °C 93% of the activity was lost.

  • 32.
    Halvarsson, Linus
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Nitrifikation i pulskärr: En studie av Forsmarks avloppsreningsverk med SBR och våtmarker2017Independent thesis Advanced level (professional degree), 300 HE creditsStudent thesis
    Abstract [en]

    Forsmark wastewater treatment plant treats wastewater using an active sludge process in sequencing batch reactors (SBR:s) and followed by constructed wetlands. The wetlands consist of four intermittent loaded soil filters (ILS:s) and a pond. The ILS:s is designed as pools filled with filter material and with a plant-grown surface. One of the ILS:s fills up with water when one of the SBR reactors is emptied. The water flows out over the surface as it percolates into the bed. When the SBR reactor is emptied, the entire ILS becomes saturated. The ILS then drains through a drainage gravel layer at the bottom and further through an adjustable drainage pipe into the dam. The purpose of the ILS:s is to work as extra filter for removal of the remaining particles and escaping sludge. They have also been thought to act as a nitrifying step if the plant would have tougher cleaning requirements in the future.

    In this report, the function of the ILS:s as nitrifying steps was investigated by compiling existing operating data from the treatment plant, with conducted field studies and through a literature review. The field study aimed at measuring ammonium, nitrate and total nitrogen in the water at the entering and the outlet in the ILS to see how the different nitrogen concentrations was affected. Temperature, oxygen, pH and electricalconductivity were also measured. The sampling was done on two ILS with different drainage time, two and four hours.

    The results showed that the ILS:s nitrifies the incoming water with an average efficiency of 50 % depending on the ammonium contentration in the incoming water. An increased drainage time for the ILS seamed to result in better nitrification. Therefore, the ILS:s should be changed to drain for at least four hours. Should the ammonium concentration increase above 3 mg/l the nitrification rate would probably be about the same. Similar systems such as have shown similar nitrification removal but with higher ammonia concentrations.

    Forsmarks wastewater treatment plant meets the purification requirements imposed on the plant with margin. It is remarkable that, without planning for any nitrogen removal, the removal is about 80 % of incoming nitrogen, most of which is removed in the SBR reactor.

    Svensk Kärnbränslehantering AB plans to lead leachate to the treatment plant for nitrogen removal. If this plan is fulfilled, the flows through the ILS will increase. This should not be a problem as the total flow trought the ILS will not exceed the capacity limits of the ILS. In case of high flows, the emptying time of the ILS:s can be reduced.

  • 33.
    Hansson, Josefin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Järns påverkan på biologisk fosforrening: en studie av reningen vid block B vid Kungsängsverket, Uppsala2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Phosphorus is an essential element but can cause eutrophication when present in high concentrations. Emission requirements from municipal wastewater treatment plants are therefore strict. Today chemical precipitation is common but there are advantages to using a biological method. It is based on creating conditions that favor growth of a special type of bacteria. These bacteria absorb more phosphorus than they need for growth. To do this they need alternating anaerobic and aerobic zones and access to carbon and phosphorus. A combination between the two methods are common but the precipitation chemicals can under some conditions disturb the biological removal.  

    At Kungsängsverket the process of biological phosphorus removal has been in place since 2010. It has not worked adequately and the reason could be high concentrations of iron in the biological sludge. The purpose of this thesis has therefore been to investigate whether it is possible to wash out the iron from the bio-sludge and as a result reach a satisfying reduction of phosphorus, to see at which iron content this might happen and what kind of savings a functioning biological phosphorus removal might lead to for Uppsala Vatten och Avfall AB.  To test the hypothesis two reactors were built, a reference reactor and an experimental reactor. The two were fed with water with different compositions, primarily regarding iron content. Also, existing data was examined from the plant and records regarding sludge composition at plants with working biological phosphorus removal.

    The pilot test showed that it was possible to wash out the iron from the biological sludge. Iron content in the experimental reactor went down from 40 mg Fe/g DM to 18 mg Fe/g DM. A satisfying reduction of phosphorus was never achieved and no conclusions can be drawn regarding savings or at which iron content a reduction might happen. Other wastewater treatment plants with biological phosphorus reduction have shown to have a content of about 10 mg Fe/g DM which can be used as an indication. According to the pilot test dosing of polymer can lead to a large precipitation of carbon source. Lack of carbon will inhibit phosphorus and nitrogen removal. Circulation of nitrate repressed the release of phosphate in the anaerobic zone and is believed to have disturbed the removal during the pilot. The conditions for biological phosphorus removal at Kungsängsverket are not ideal as to the composition of the wastewater, the circulation of nitrate to the anaerobic zone and the amount of carbon source from the hydrolysis.

  • 34.
    Henriksson, Linnea
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Renare dagvatten från kvarteret Brännugnen2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Stormwater is rain and snow melt that runs off from hard surfaces. Stormwater is often polluted with heavy metals and organic pollutants, which can cause great damage if the water is not treated before it reaches the recipient. There are no national guidelines for threshold values of pollutants in stormwater. The stormwater group at Vattenfall AB Heat Uppsala and the environmental department at Uppsala municipality have together established threshold values for pollutants in the stormwater from the area Brännugnen, which is the name of the investigated area. Vattenfall has difficulties to keep the concentration of pollutants in the stormwater below the threshold values. To reduce the content of contaminants in the stormwater from the area Brännugnen this study was therefore carried out.

    Through site investigations and sampling of stormwater in six measuring points, sources of the contaminants were identified. Through literature studies, site investigations and discussions with experienced personnel, propositions of actions to avoid contamination of the stormwater have been developed. The stormwater study has also led to suggestion of an improved sampling strategy which better represents the amount of contaminants in the stormwater and is more cost-effective. The study included an investigation with the purpose to find out if the magazine that the stormwater from half of the area runs to have the capacity to reduce the contaminants. The results showed no reduction of contaminants. The reason is that the residence time is too short for the particles to have time to settle. In the study the contribution from condensate to the total amount of emitted metals in the stormwater was investigated. The condensate passes a treatment plant for purification before being discharged to the stormwater pipes. The result shows that the condensate has a large impact on the amount of emitted metals per year. Threshold values and standard values for stormwater was also studied, the conclusion is that the threshold values for the stormwater from the area Brännugnen are low. Both standard values for stormwater from thermal power stations and roads are higher than the threshold values. The results from the analyses of stormwater from the road outside the area Brännugnen also show higher concentrations of metals than the threshold values.

    Finally the stormwater study resulted in suggestions of technical solutions for future treatment of the stormwater from the area Brännugnen. An underground sedimentation magazine and a filter system are two treatment processes that can be used for removal of pollutants in the stormwater from the area Brännugnen.

  • 35.
    Jonfelt, Clara
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing.
    An evaluation of an MBBR anammox model - sensitivity analysis and calibration2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

     This master thesis is about mathematical modelling of the anammox process with a

    moving bed biofilm reactor (MBBR) for a reject water application. Specifically, the aim

    of my research was to find out whether the model proposed by Erik Lindblom in

    (Lindblom et al. 2016) is a good model for this purpose and worth continuous

    research and optimization.

    The code for the model, implemented in Matlab/Simulink, was given; although not

    initially functioning in the given condition. Some modifications needed to be done to

    make it function properly. In order to confirm that the code was working and used in

    a correct way some results in (Lindblom et al. 2016) were reproduced. Before

    starting the evaluation of the model, some much-needed optimizations of the code

    were done, substantially reducing the run time.

    A sensitivity analysis was done, and the five most sensitive parameters were picked

    out to be used in the calibration. The calibration improved the total fit of the model

    to the available measurements, although one of the model outputs could not be

    calibrated satisfactorily.

    In short, I found that although there are still problems left to solve before the model

    can be stated to accurately model the anammox process with MBBR, it appears

    promising. Most importantly, more measurement data are needed in order to make a

    proper validation and to do a better calibration.

  • 36.
    Kamp, Matilde
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    Flytslam i Lövsta avloppsreningsverk: påverkande faktorer och potentiella åtgärder2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    One of the most crucial steps in wastewater treatment with activated sludge is the separation of sludge from the treated effluent. This is most often done by sedimentation in clarifiers. Sedimentation problems are, however, common in many wastewater treatment plants, causing higher concentrations of pollutants in the effluent. Research on sludge characteristics is therefore important to increase the knowledge about which factors affect the sludge settling properties and what can be done to minimize problems. In this master thesis a small wastewater treatment plant in Lövsta outside Uppsala, Sweden, was investigated. About a third of the influent water to the plant comes from a slaughterhouse situated nearby. The plant suffers from recurrent problems with rising sludge in the secondary clarifier. The purpose of this thesis was to – through literature studies, sampling, full scale experiments and analysis – identify causes for the rising sludge problem. Also, suggestions to remedy the problem were to be presented. An evaluation of the treatment process was conducted from existing measurement data and from sampling and measuring done for three weeks in October. High concentrations of nitrate were found in the water, especially in the equalization tank, where flow equalization and primary treatment of the slaughterhouse wastewater takes place. The high concentrations of nitrate, in combination with a long sludge retention time in the secondary clarifier, were judged to be the reason for the formation of rising sludge. Both of these factors stimulate the development of nitrogen gas through denitrification. This gas lifts the sludge from the bottom of the clarifier to the water surface. Two possible solutions to the rising sludge problem were considered feasible. One was to increase the pumping of sludge from the bottom of the secondary clarifier, to decrease the sludge retention time. The second was to denitrify the water before it reaches the clarifiers. Of these two suggestions, the second was regarded as more appealing from both an economical and an environmental point of view. One method to denitrify the water was deemed to be intermittent aeration in the equalization tank. This aeration strategy was implemented for ten weeks. Nitrate concentrations were measured one or two times a week for this period of time. A decrease in nitrate concentrations was observed: from 182 mg/L to at its lowest 62 mg/L in the equalization tank, and from 65 mg/L to at its lowest 18 mg/L in the aeration tank. The decrease was, however, not enough to prevent formation of rising sludge in the clarifiers. The incomplete denitrification process was thought to be due to low concentrations of BOD in the equalization tank. Further studies need to be carried out to evaluate and optimize the nitrogen removal through intermittent aeration.

  • 37. Krona, Johanna
    Evaluation of a bark adsobent for removal of pharmaceuticals from wastewater2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    During and after medical treatment, pharmaceutical compounds as well as their metabolites

    and conjugates are excreted from the users through urine and feces. The pharmaceuticals

    end up in wastewater treatment plants, which are not designed to deal with this

    kind of organic micro-pollutant. Eventually the pharmaceuticals end up in the environment

    where they can have adverse physiological and behavioral effects on aquatic life

    and could contribute to the spread of antibiotic resistance among microorganisms. Adsorption

    to activated carbon is an established method for removal of pharmaceuticals

    from wastewater. It is however quite expensive and it is of interest to identify cost-effective

    alternatives. One possible alternative is bark, which is a common by-product

    from forest industry and has a complex microstructure and high porosity compared to

    many other naturally occurring materials.

    In order to investigate the potential of using bark to remove pharmaceuticals from municipal

    wastewater four column filters were built, two with activated carbon and two

    with bark. They were used in an experiment conducted at Kungsängsverket, the largest

    wastewater treatment plant in Uppsala municipality. The objectives were to assess pharmaceutical

    concentrations in treated wastewater at Kungsängsverket and to compare the

    performance of bark and activated carbon filters under different loading rates. During

    this time the filters were run at different loading rates and two different types of bark

    was used. 24 common pharmaceuticals from different therapeutic groups were targeted.

    The pharmaceutical concentrations measured at Kungsängsverket were generally low,

    but mean concentrations of five pharmaceuticals (atenolol, metoprolol, furosemide, hydrochlorothizide

    and diclofenac) exceeded 250 ng/l. Out of these, four have been shown

    to have adverse effects on aquatic life and it would be preferable if they were not released

    into the recipient.

    Bark was not as good at removing pharmaceuticals from wastewater as activated carbon

    was, but decent removal rates were achieved for several compounds. The removal rates

    of either filter type did not seem to be significantly impacted by variations in loading

    rate or bark size. The concentrations of a few compounds increased after treatment with

    the bark filters and the reason for this is not clear. One possibility is interference from

    other organic substances in the wastewater or the bark, but determining the reason for

    this increase should be a priority for any further research on the subject.

    Another problem encountered during the project that is likely to pose a problem for future

    implementation is that the bark filters were very sensitive to clogging. Running the

    filters at full scale would require frequent back-washing which would be a disadvantage

    from both economical and practical reasons.

  • 38.
    Lundgren, Erika
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    A method for water disinfection with solar pasteurisation for rural areas of Bangladesh2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In order to improve the water situation in rural areas of Bangladesh, a research group at the University of Dhaka has been developing low cost domestic methods to remove pathogens from surface water through pasteurisation using free solar energy. Pasteurisation is a process in which water is heated to approximately 60 °C and maintained for about 30 minutes to destroy pathogens. In these methods, the water is also exposed to UV-light from the sunshine, which causes destruction of diarrhoeal pathogens at temperatures somewhat lower than required in normal pasteurisation. However, despite many advantages these devices need to be installed for each time of use.

    Recently, a semi-permanent device has been developed which is expected to be more user friendly. The objective of this Master thesis has been to study and optimize the low cost semi-permanent device that can deliver safe drinking water to people in rural areas. Two test devices were constructed to determine the most effective treatment e.g. temperature, time, solar radiation, user-friendliness and cost. To replicate the results from the solar heating tests a model, based on the solar radiation and convective heat loss from the device, was used. The model was also able to determine the time duration at a certain solar radiation level to estimate when the water is safe to drink.

    The results revealed that the performance of the device depends on thickness of the insulation and thickness of the air gap. This is because the most important factors to achieve safe drinking water are solar radiation and time. The modelling indicated that the measured water temperature corresponds well with the calculated water temperature and also showed that the lowest required solar radiation is 390 W/m2 to reach drinking water criteria, at an air temperature of 25 °C. A study of microbiology showed that the semi-permanent low cost device could purify surface water to a safe level.

  • 39.
    Matschoss-Falck, Emma
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Lokalt omhändertagande av dagvatten i Västerås - Möjligheter till ökad användning i befintliga innerstadsområden: Local disposal of storm water i Västerås - possibilities for increased use in downtown areas2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The construction of buildings and paved surfaces changes the natural water balance.

    Precipitation generates surface runoff and storm water instead of infiltrating into the soil.

    Storm water has come to be considered as a major source of pollution in lakes and streams in

    the vicinity of urban areas. Reduction of pollutants in storm water is a key action in order to

    protect sensitive recipients and maintain high water quality. Storm water is traditionally

    transported by storm sewers to the nearest recipient. In recent years the approach to storm

    water management has changed; storm water should primarily be disposed of on site, through

    local disposal of storm water, LOD. LOD is created by a combination of the function of

    several smaller local facilities and the general sewer system. In LOD techniques like wet and

    dry ponds, ditches, rain gardens, infiltration areas and green roofs are used. The function of a

    LOD facility is reduction, equalization and delay of storm water flows. There are several

    advantages of LOD over traditional storm water management. The natural water balance is

    imitated, exposed water surfaces and green areas are perceived as aesthetically pleasing, a

    reduction of pollutants occurs and the load on the grid is reduced

    The aim of this work was to investigate the conditions and strategies for increased use of

    LOD in existing urban areas in Västerås. This was done by examining two areas in Västerås

    city center and by suggesting LOD solutions. Private land and public land has been

    distinguished between for each area. The LOD plant is dimensioned so that the total outgoing

    flow is limited to 10 l / s, hectare. It has been investigated if the requirements for outbound

    flows from private property can be set lower and flows reduced by a further delay on public

    land or if it is more advantageous to delay the flows individually. To simulate flow and

    magazine volumes, the program StormTac has been used.

    The investigation has shown that storm water volumes to be disposed will be much lower if

    the disposal is done in one step. Available lawns should be used wherever possible to

    construct dry ponds, swales or other technics based on infiltration. By using lawns, large

    volumes can be disposed, pollution is reduced effectively and the arrangement is relatively

    cheap. Rain gardens are more expensive to construct but provide an efficient cleaning of

    storm water and are nice from an aesthetic point of view. Rain gardens should be placed

    lengthwise along roads or pedestrian streets. With such a design, large storage volumes are

    created while the surrounding areas can still be used. The use of percolation basins are

    needed when using LOD in urban paved areas. With the use of LOD plants, pollutants are

    reduced enough to reach the values

    and goals in Västerås’ storm water plan.

  • 40.
    Mellhorn, Malin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Water hyacinths (Eichornia crassipes) and their presence in Shire River, Malawi: Problems caused by them and ways of utilise them elsewhere2013Student paper other, 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Malawi is one of many countries throughout the world struggling with massive amounts of water hyacinths (Eichornia crassipes) in the country’s fresh water resources.  In nutrient-rich ecosystems where the aquatic weed has no natural enemies it will reproduce very rapidly with the consequence that lakes become overgrown, water flow in rivers is reduced, and other water organisms becomes excluded. At the same time, the plants form a good breeding place for species carrying tropical diseases for example Malaria and Bilharzia. Water hyacinths are usually more of a problem for poorer countries since there are often great economic losses caused by the weed and to control their relative abundance is costly.

    In Malawi, 99 % of the produced electricity is based on water resources, mainly through hydropower turbines in the main river, Shire River. Water hyacinths, aggregated as islands, floating along the river and clogging the turbines cause repeated electricity black-outs and approximately 140 megawatt power is lost every day. To counter the weed interference with the electricity supply, there are great amounts of water hyacinths harvested every day and dumped along the road, with no further disposal plan. In this report, soil from one local dumping area is analysed to determine if such places are leaching nutrients or metals to the surrounding environment. 

    Water hyacinths contain naturally high values of nutrients and farmers use these harvested plants as a green manure to improve soil properties on agricultural land. This paper aims to examine levels of metal in water hyacinths used as green manure. This is of interest since water hyacinths have the ability to effectively absorb substances from the water body which could pose a risk for potentially toxic elements (PTEs) to accumulate in the agricultural soil and subsequently in crops.

    Sampling and analyses were carried out with standard methods. Metal and nutrient levels in the analysed samples were obtained through detection with atomic absorption spectrophotometry (AAS), ion chromatography (IC) and UV/VIS spectrophotometry at the Department of Chemistry of Chancellor College in Zomba, Malawi.

    None of the investigated metal ions (Cr, Pb, Cd) were found in the analysed water hyacinths and since soil sampling was done during the dry season this thesis cannot determine if the dumping areas are leaching nutrients. Relatively high amounts of total phosphorus were found in the plants. Overall, the conclusion is that there is no risk of using water hyacinths harvested in Shire River as a green manure on agricultural land. 

  • 41.
    Murad, Hassan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Membranbioreaktorer och deras förmåga att avlägsna prioriterade mikroföroreningar2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Release of pharmaceutical residues and other emerging substances in the environment has been highlighted and raised a great concern regarding the issue. Among observations that scientists have noted as a result of antibiotics, hormones and pharmaceutical residues in the aquatic environment are bacterial resistance, sex change and sterility in fish and batrachians.

    Persistent pollutants such as perfluorinated-alkylated substances (PFAS) are also not degraded in nature, and microscopic debris particles can be enriched in aquatic systems and cause adverse effects on aquatic organisms. The common aspect with these substances is that they usually occur in small quantities and can derive from different human activities.

    Wastewater treatment plants (WWTP) are not primarily designed to separate emerging substances of concern (ESOC), but primarily to remove nitrogen, phosphorus and particulate organic matter. Upstream work is also not sufficiently effective to relieve the purification process, which means that the amount of pollutants increases in aquatic environments and puts additional pressure on the WWTP. The challenges facing WWTP today with ESOC and their presence in the environment has raised issues both nationally and internationally. Stockholm Vatten och Avfall (SVOA) decision to implement a membrane bioreactor (MBR) with poresize of 0,04 μm at Henriksdal WWTP is a step to prepare for future hydraulic volumes, but also potentially stricter treatments requirements regarding ESOC. The advantage of the MBR process is that it prevents contaminants that appear to be particulate to pass the membranes and end up in the receiving waters.

    Today, WWTP are not required to treat wastewater in order to remove pharmaceutical residues, antibiotics, hormones, PFAS or microscopic debris particles. However, it is expected that future legislations will include pharmaceuticals and other organic pollutants. In this project, ESOC such as pharmaceutical residues, antibiotics, hormones, PFAS and microscopic debris in the MBR-process are studied as well as the presence of adsorbable and extractable organic halogens (AOX, EOX) that are possibly formed during the cleaning or maintains of the membranes.

    Results from this study showed a higher general reduction of the studied ESOCs in wastewater with the MBR-process than previous studies in conventional WWTP, except of some substances that showed a poor reduction. Pharmaceuticals such as diclofenac, oxazepam and citalopram showed a weak reduction as well as the antibiotics clindamycin, clarithromycin and erythromycin where they showed a higher outcome levels than the incoming to the treatment process. Estrogenic hormones were reduced in the purification process as well as microplastics where only 60 particles/m3 of pore size higher than 300 μm passed the membranes. Microplastics of the pore size smaller than 300 and larger than 50 μm were detected to 140 particle/m3 in the effluent water.

    For AOX and EOX, the level of MBR process showed typical values and were in line with previous studies on conventional ARV. However, since the membranes cannot treat contaminants at molecular level, it was also shown that some ESOC that were studied bypassed the treatment process.

    A conclusion from this project is that only a few numbers of substances were fully reduced while the majority of ESOCs were partially reduced in wastewater. In order to reduce further ESOCs and in case of stricter treatment were to be applied, additional post-treatment is also needed for the MBR process.

  • 42.
    Nordström, Albin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Biogeochemical Processes in Denitrifying Woodchip Bioreactors and their Application in the Mining Industry2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis evaluates passive denitrifying woodchip bioreactors (DWBs) for the removal of nitrate (NO3-) in neutral pH mine drainage, where water is passed through a carbon-rich porous matrix (e.g. woodchips) for the reduction of NO3- to nitrogen gas. DWBs have been used for the removal of NO3- from water in various settings and are expected to operate with little maintenance for at least a decade; however, the processes controlling the emission of greenhouse gases and other undesirable by-products, as well as the magnitude and variability in NO3- removal rates and how these develop over time, are not completely understood and were the focus of this thesis.

    Water treatment in DWBs was investigated in laboratory-scale column tests and in a pilot-scale bioreactor installed at the Kiruna iron ore mine, northern Sweden. Denitrification was the major pathway for NO3- removal in both experimental systems. Incoming NO3- concentrations (up to 30.0 mg N L-1) were removed to below detection limits at temperatures and hydraulic residence times (HRTs) between 5-22°C and ~1.9-2.6 days, respectively, without substantial production of nitrite or ammonium (NH4+). NO3- removal was incomplete in both systems when HRTs decreased to ~1 day, and/or as temperature decreased below 5°C in the pilot-scale bioreactor, under which conditions an increased production of nitrous oxide (N2O) and NH4+ was observed (relative to the NO3- reduced).

    In the column tests, non-ideal flow was detected and solute transport was described using a dual-porosity model. Stagnant zones not transmitting flow did not participate in NO3- removal and the fraction of immobile water increased with increases in the advection velocity, suggesting that bioreactor performance could be enhanced by emphasizing design with low advection velocities.  

    The study demonstrated that dominating biogeochemical processes varied with time in the pilot-scale bioreactor. There was a decline in organic carbon export and increase in pH and alkalinity that, based on a stoichiometric mass-balance, was suggested to be the result of a change in fermentation end-products that provided a carbon source to the denitrifying community. The decline in NO3- removal rates and biogeochemical process diversity, and the preferential selection of denitrifiers with the genetic capacity for reduction to N2O, but not N2, are hypothesized to arise from the temporal development of syntrophic structures between fermenters and denitrifiers.

    List of papers
    1. Denitrification in a low-temperature bioreactorsystem at two different hydraulic residence times: laboratory column studies
    Open this publication in new window or tab >>Denitrification in a low-temperature bioreactorsystem at two different hydraulic residence times: laboratory column studies
    2017 (English)In: Environmental technology, ISSN 0959-3330, E-ISSN 1479-487X, Vol. 38, no 11, p. 1362-1375Article in journal (Refereed) Published
    Abstract [en]

    Nitrate removal rates in a mixture of pine woodchips and sewage sludge were determined in laboratory column studies at 5°C, 12°C, and 22°C, and at two different hydraulic residence times (HRTs; 58.2–64.0 hours and 18.7–20.6 hours). Baffles installed in the flow path were tested as a measure to reduce preferential flow behavior, and to increase the nitrate removal in the columns. The nitrate removal in the columns was simulated at 5°C and 12°C using a combined Arrhenius-Monod equation controlling the removal rate, and a first-order exchange model for incorporation of stagnant zones. Denitrification in the mixture of pine woodchips and sewage sludge reduced nitrate concentrations of 30 mg N L−1 at 5°C to below detection limits at a HRT of 58.2–64.0 hours. At a HRT of 18.7–20.6 hours, nitrate removal was incomplete. The Arrhenius frequency factor and activation energy retrieved from the low HRT data supported abiochemically controlled reaction rate; the same parameters, however, could not be used to simulate the nitrate removal at high HRT. The results show an inversely proportional relationship between the advection velocity and the nitrate removal rate, suggesting that bioreactor performance could be enhanced by promoting low advection velocities.

    National Category
    Oceanography, Hydrology and Water Resources
    Research subject
    Hydrology
    Identifiers
    urn:nbn:se:uu:diva-303686 (URN)10.1080/09593330.2016.1228699 (DOI)000400464400004 ()27603564 (PubMedID)
    Projects
    MiNing
    Funder
    VINNOVA, P31054-1
    Available from: 2016-09-22 Created: 2016-09-22 Last updated: 2019-03-27Bibliographically approved
    2. Determination of major biogeochemical processes in a denitrifying woodchip bioreactor for treating mine drainage
    Open this publication in new window or tab >>Determination of major biogeochemical processes in a denitrifying woodchip bioreactor for treating mine drainage
    2018 (English)In: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 110, p. 54-66Article in journal (Refereed) Published
    Abstract [en]

    At the Kiruna iron ore mine in northern Sweden, mine drainage and process water contain elevated concentrationsof nitrate (NO3−) from the use of ammonium nitrate fuel oil explosives. In order to investigate thetreatment capacity of a denitrifying woodchip bioreactor technique for the removal of NO3− through denitrification,a bioreactor was installed at the mine site in 2015 and operated for two consecutive years. Neutral-pHmine drainage and process water containing 22 mg NO3−-N and 1132 mg SO42− (average) was passed throughthe bioreactor which was filled with a reactive mixture of pine woodchips and sewage sludge, at treatmenttemperatures ranging between 0.8 and 17 °C. At bioreactor temperatures above ∼5 °C, NO3− removal proceededto below detection limits (0.06 mg N L−1) without substantial production of nitrite (NO2−), ammonium(NH4+), nitrous oxide (N2O), or methane (CH4). The relative production of NH4+ and N2O to the NO3− reducedincreased as bioreactor temperatures decreased below ∼5 °C. Based on the resultant changes in alkalinity andpH from the production of bicarbonate (HCO3−) and carbonic acid (H2CO3), a stoichiometric mass balancemodel indicated that denitrification, nitrate reduction to ammonium (DNRA), sulfate reduction, and fermentationwere the major biogeochemical processes controlling pH, alkalinity and nitrogen, sulfur and carbonconcentrations in the system. It is suggested that fermentation changed from being mainly butyrate producing toacetate producing with time, triggering a decline in biogeochemical process diversity and leaving denitrificationas the sole major electron accepting process.

    Keywords
    Denitrification, sulfate reduction, DNRA, woodchip bioreactor, temperature, biogeochemical processes, mine drainage, nitrogen, denitrifikation, sulfatreduktion, DNRA, bioreaktor med träflis, temperatur, biogeokemiska processes, gruvvatten, kväve
    National Category
    Geochemistry
    Research subject
    Hydrology
    Identifiers
    urn:nbn:se:uu:diva-331698 (URN)10.1016/j.ecoleng.2017.09.018 (DOI)000417048500007 ()
    Projects
    miNing
    Funder
    VINNOVA, 2014-01134
    Available from: 2017-10-17 Created: 2017-10-17 Last updated: 2019-03-27Bibliographically approved
    3. Identification of the temporal control on nitrate removal rate variability in a denitrifying woodchip bioreactor
    Open this publication in new window or tab >>Identification of the temporal control on nitrate removal rate variability in a denitrifying woodchip bioreactor
    2019 (English)In: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 127, p. 88-95Article in journal (Refereed) Published
    Abstract [en]

    Nitrate (NO3) removal rates in a denitrifying woodchip bioreactor (DWB) removing NO3 from mine water in a subarctic climate was modeled with the purpose of determining the processes controlling variability in NO3 removal rates over time. The Eyring equation was used to define the temperature dependency, while a rate law was used to describe the NO3 concentration dependency of the NO3 removal rates. The results show that the temperature and NO3 concentration dependency of the NO3 removal rates changes over time in the DWB due to the preferential selection of conceptualized NO3 - reducing bacteria favoring low temperatures, with the mean temperature optimum of the NO3 reducing consortium decreasing from 24.2 °C to 16.0 °C following the first year of DWB operations. It is suggested that the selection of the low temperature NO3 reducers in the DWB represented an increased dependence on cross-feeding between a fermentative community, producing the reactive organic carbon substrate, and a denitrifying community, consuming the organic carbon substrate, with the temporal variability in NO3 removal rates being controlled by the stabilization of the microbial community structure. It is also suggested that the life expectancy of DWBs is more related to the stability of the cross-feeding between the fermenting microbial community and the denitrifying microbial community, than to the total carbon content.

    Keywords
    Woodchip bioreactor, Modeling, Macromolecular rate theory, Selection, Temperature, Longevity
    National Category
    Water Treatment
    Identifiers
    urn:nbn:se:uu:diva-366588 (URN)10.1016/j.ecoleng.2018.11.015 (DOI)000455632500009 ()
    Funder
    VINNOVA, 2014-01134
    Available from: 2018-11-21 Created: 2018-11-21 Last updated: 2019-03-27Bibliographically approved
    4. Microbial Controls on Net Production of NOx Species in a Denitrifying Woodchip Bioreactor
    Open this publication in new window or tab >>Microbial Controls on Net Production of NOx Species in a Denitrifying Woodchip Bioreactor
    (English)Manuscript (preprint) (Other academic)
    National Category
    Water Treatment
    Identifiers
    urn:nbn:se:uu:diva-380384 (URN)
    Projects
    miNing
    Funder
    Vinnova, 2014-011334
    Available from: 2019-03-27 Created: 2019-03-27 Last updated: 2019-03-27
  • 43.
    Nordström, Albin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Hellman, Maria
    Sveriges Lantbruksuniversitet, institutionen för skoglig mykologi och växtpatologi.
    Hallin, Sara
    Sveriges lantbruksuniversitet, instutionen för skoglig mykologi och växtpatologi.
    Herbert, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Microbial Controls on Net Production of NOx Species in a Denitrifying Woodchip BioreactorManuscript (preprint) (Other academic)
  • 44.
    Nordström, Albin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Herbert, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Identification of the temporal control on nitrate removal rate variability in a denitrifying woodchip bioreactor2019In: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 127, p. 88-95Article in journal (Refereed)
    Abstract [en]

    Nitrate (NO3) removal rates in a denitrifying woodchip bioreactor (DWB) removing NO3 from mine water in a subarctic climate was modeled with the purpose of determining the processes controlling variability in NO3 removal rates over time. The Eyring equation was used to define the temperature dependency, while a rate law was used to describe the NO3 concentration dependency of the NO3 removal rates. The results show that the temperature and NO3 concentration dependency of the NO3 removal rates changes over time in the DWB due to the preferential selection of conceptualized NO3 - reducing bacteria favoring low temperatures, with the mean temperature optimum of the NO3 reducing consortium decreasing from 24.2 °C to 16.0 °C following the first year of DWB operations. It is suggested that the selection of the low temperature NO3 reducers in the DWB represented an increased dependence on cross-feeding between a fermentative community, producing the reactive organic carbon substrate, and a denitrifying community, consuming the organic carbon substrate, with the temporal variability in NO3 removal rates being controlled by the stabilization of the microbial community structure. It is also suggested that the life expectancy of DWBs is more related to the stability of the cross-feeding between the fermenting microbial community and the denitrifying microbial community, than to the total carbon content.

  • 45. Nájera, Silvano
    et al.
    Gil-Martínez, Montserrat
    Zambrano, Jesús A.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    ATAD control goals through the analysis of process variables and evaluation of quality, production and cost2015In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 71, no 5, p. 717-724Article in journal (Refereed)
    Abstract [en]

    The aim of this paper is to establish and quantify different operational goals and control strategies in autothermal thermophilic aerobic digestion (ATAD). This technology appears as an alternative to conventional sludge digestion systems. During the batch-mode reaction, high temperatures promote sludge stabilization and pasteurization. The digester temperature is usually the only online, robust, measurable variable. The average temperature can be regulated by manipulating both the air injection and the sludge retention time. An improved performance of diverse biochemical variables can be achieved through proper manipulation of these inputs. However, a better quality of treated sludge usually implies major operating costs or a lower production rate. Thus, quality, production and cost indices are defined to quantify the outcomes of the treatment. Based on these, tradeoff control strategies are proposed and illustrated through some examples. This paper's results are relevant to guide plant operators, to design automatic control systems and to compare or evaluate the control performance on ATAD systems.

  • 46.
    Oskarsson, Lina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Frihammar, Esmeralda
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Wallin, Mathias
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Gobl, Madeleine
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Kjellgren, Ylva
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Lampinen, Alexi
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Jonsson, Jennifer
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Sensorbaserad kvalitetskontroll av råvatten2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna rapport är utförd på uppdrag av företaget Norrvatten vilka driver vattenverket Görvälnverket i Jakobsberg utanför Stockholm. Studien är uppdelad i tre huvudmål. Det första målet innefattar att utföra en analys av befintlig mätdata från en sensor som sitter inuti vattenverket. Data från verket jämfördes med väderdata för att få fram eventuella samband. Information om samband skulle kunna leda till att Norrvatten kan använda sin mätutrustning mer effektivt. I analysen användes MatLab och vissa samband mellan TOC (Total Organic Carbon), nederbörd och vattenstånd kunde ses och tydliga säsongstrender kunde även urskiljas. Det andra målet var att komma med ett förslag på mätsystem för kartläggning av skiktningen i vattnet utanför vattenverket Görvälnverket. Syftet med kartläggningen är att se om det finns behov av ett nytt, djupare, råvattenintag. Det tredje målet var att komma med ett förslag på ett alternativ på ett sensorbaserat varningssystem för förändrad råvattenkvalitet utanför verket. Systemets syfte är att ge information till verket om förhöjda halter av förorenande ämnen. För varningssystem och kartläggning av skiktning användes ett bedömningssystem för att väga olika alternativ till mätsystem mot varandra. Bedömningssystemet bestod av tre urvalsmatriser vilka vägde in hur många parametrar som kunde mätas, hur väl de kunde mätas samt kostnader. Utifrån urvalsmatriserna valdes de mest lämpade alternativen för respektive mätsystem. För att kartlägga skiktningen valdes ett mätsystem bestående av sensorer sittande på befintliga provtagningsledningar vid intagsledningarna i verket. För det sensorbaserade varningssystem valdes ett system med sensorer från företaget PME. Mätsystem är tänkt att placeras på egenbyggd plattform under vattnet. Det placeras sedan runt verket för att mäta olika parametrar.

  • 47.
    Persson, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Sveriges Lantbruksuniversitet.
    Calibration and Application of Passive Sampling in Drinking Water for Perfluoroalkyl Substances2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Perfluoroalkyl substances (PFASs) are global environmental contaminants and a need for monitoring levels has arisen due to their persistency and their ability to bioaccumulate. One relatively novel method of monitoring for both long and short time intervals and generating time-weighted average (TWA) concentrations is passive sampling for which no power, maintenance and supervision is required. The polar organic compound integrative sampler (POCIS) with a weak anion exchange (WAX) sorbent and the POCIS with a hydrophilic-lipophilic balance (HLB) adsorbent were calibrated for PFASs in a laboratory uptake experiment, and applied at a drinking water treatment plant (DWTP) in Stockholm, Sweden.

     

    In the calibration study, all of the 14 studied PFASs were taken up by both passive samplers. Two and three out of the 14 studied PFASs had reached equilibrium after 28 days using POCIS WAX (PFBA and PFTeDA) and POCIS HLB (PFBA, PFPeA and PFTeDA), respectively. The sampling rate (Rs), which is the extracted water in liters per day, ranged between 0.003 and 0.10 L day-1 for the POCIS WAX and between 0.00052 and 0.13 L day-1 for the POCIS HLB. In general, Rs increased with increasing perfluorocarbon chain-length (C4 to C8) and for a perfluorocarbon chain-length longer than C8, Rs decreased with increasing perfluorocarbon chain-length (C8 to C13) for both passive samplers. FOSA had the highest Rs-value (0.10 and 0.13 L day-1) for both POCIS WAX and POCIS HLB, respectively. The POCIS WAX had a higher uptake for the short-chained PFASs PFBA (134 ng after 28 days), PFPeA (410 ng) and PFHxA (834 ng), compared to the POCIS HLB (0.5 ng, 58 ng, and 373 ng, respectively). For all other compounds, the accumulated amounts in the POCIS HLB were in the same range as in the POCIS WAX.

     

    The application of the passive samplers at the DWTP showed that both passive samplers could detect ultra-trace (pg to ng L-1) levels of PFASs. A comparison of the TWA concentration showed that the two passive samplers had a good linear correlation (R2 = 0.63), but the TWA concentrations derived by POCIS WAX was approximately 40% higher compared to POCIS HLB. A comparison between the passive samplers and the grab samples did not show a correlation (R2 = 0.24 for POCIS WAX and R2 = 0.10 for POCIS HLB). The application also included a comparison of the removal efficiency in the conventional DWTP and a pilot plant with additional treatments steps of granulated activated carbon (GAC) and nanofiltration (NF). For the full-scale DWTP the average removal efficiency was 32% and high removal efficiency was observed for PFBA (81%). For the pilot plant, the removal efficiency was 100% for all the detected PFASs in the raw water.

  • 48. Pierong, Rasmus
    et al.
    Nehrenheim, Emma
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Zambrano, Jesús
    Algae Based Wastewater Treatment Model Using The RWQM12016In: Proc. IWA World Water Congress & Exhibition: 2016, 2016Conference paper (Other academic)
    Abstract [en]

    In this paper, we propose a model describing the dynamics of an algae based wastewater treatment process in an activated sludge environment. As the basis for the process modelling, the River Water Quality Model no. 1 (RWQM1) is chosen. In order to evaluate the applicability of the model to an activated sludge process, the proposed model is compared to the Activated Sludge Model no. 1 (ASM1).

  • 49.
    Renström, Terese
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Kartläggning av metallflöden i avloppsvatten i Västerås2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sludge, produced in the waste water treatment process, can be used as fertilizer in agriculture. It is rich in nutrients but also contains other substances, such as heavy metals. Metals may enter crops which means that it also enters the food chain. Some heavy metals have been proven to cause severe damage to living organisms in high doses. It is therefore important to regulate the amount of heavy metals in the soil and in the sludge used as fertilizer. In this thesis the sources of heavy metals in the waste water system in the town of Västerås was examined. The sources of the heavy metals cadmium, chromium, mercury, copper and zinc were mainly analyzed by using the Excel tool "Source Finder". In this tool collected data of emissions or calculated emissions by the use of model values were entered. Households proved to be the single largest source of all the metals in this study, with the exeption of chromium. For cadmium and chromium water leakage from the ground water into the pipe system was a large contributing source. Business did not prove to be a large source of any metal with the exception of dental units which emitted large amounts of mercury. To be able to predict change of quality, in regards of metals, in the sludge and puried water an existing model of the water treatment plant was supplemented with processes regarding separation of copper. This was done by studying other models regarding metal partitioning and separation. The final model proved unable to describe variances in the measured data, but could describe the median concentration of copper in cleansed water and sludge.

  • 50.
    Robertsson, Jonas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Andersson, Camilla
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Characterisation and removal of heavy metals in tannery effluents through the use of local materials2014Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Chromium and other heavy metals are known to cause issues related to human and environmental health when they occur in high concentrations in ecosystems. Chromium poses a particularly large threat if it occurs in its hexavalent form, Cr(VI), as it is highly reactive and carcinogenic. The aim of this project was to investigate the wastewater emitted from a tannery in Liwonde, Malawi, with respect to the metals Cr, Al, Cd, Cu, Fe, Mn, Pb and Zn, and to reduce the concentrations using locally available materials. A particular emphasis was put on chromium.

     

    Wastewater collected from the tannery was analysed to determine the total and dissolved concentrations of the metals using a Microwave Plasma-Atomic Emission Spectrometer (MP-AES). The wastewater was then mixed with various dosages of peeled and unpeeled Moringa Oleifera seed powder as well as pure Moringa Oleifera shell powder and sand collected from river Shire. Thereafter, the remaining concentrations of metals were analysed. Additional analyses of various contact times were performed for the removal agent that had shown the best results.  

     

    The analyses showed a total chromium concentration of 2.25 ppm and a dissolved chromium concentration of 0.251 ppm in the wastewater discharged from the tannery. Both concentrations were lower than what had initially been expected but still above both the WHO guideline value for chromium in drinking water and the Swedish threshold value for chromium in industrial wastewater (0.05 ppm). No other metals were found in concentrations above trace levels. All of the investigated removal agents, except for pure shell powder, showed positive results for chromium removal. The highest removal observed for dissolved chromium was 72 % and occurred with a removal agent mixture of 5.0 g of river sand and 2.0 g of unpeeled Moringa Oleifera seed powder to 100 mL of wastewater. The reduction of total chromium was 97 % for the same removal agent mixture. However, lower dosages of the removal agents also gave a chromium removal of similar size. Due to resource limitations, no analysis of whether the wastewater contained Cr(III) and Cr(VI) could be performed.

     

    Considering the low initial concentrations of metals emitted from the tannery, there is no urgent need for further treatment of the wastewater. This study has however substantiated the theory that Moringa Oleifera seeds can be used as a low-cost chromium remediation agent in wastewater, a result that can be of use to improve the water quality in other industries and applications.

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