Although being the third largest city in South Africa, the outskirts of Durban are scarcely populated. Due to economic limitations, the drainage and fresh water pipes from the city are not extended to the outskirts. One of the most important issues concerning human health is that of sanitation and waste management. Lack of sanitation leads to the spreading of pathogens and often results in outbreaks of infectious diseases, such as cholera; one outbreak motivated eThekwini Municipality to install 100,000 urine-diverting toilets in rural areas of Durban. The use of UD toilets can be improved by the use of vermicomposting. Vermicomposting uses earthworms to facilitate degradation of organic material.
The aim for this project was to establish whether vermicomposting could improve the function of dry toilet systems, mainly by reducing the volume of the solid fraction.
Three toilets were chosen as testing sites. Vermicomposts were created in plastic boxes by adding different types of compost materials, so-called bedding materials, and worms. Two types of bedding material were used, vegetable compost and local topsoil were compared to potting soil and fully digested sludge mixed with soil.
Once the vermicomposts had been installed in the toilets, experiments were conducted to determine the performance of the composts. Samples were taken in the field and analysed in the lab. The number of worms and cocoons were counted and the pH, temperature and total and volatile solids were measured and calculated. Solvita® tests were made to determine the state of the composts.
In the laboratory test it appeared that the bedding material consisting of potting soil and fully digested sludge was more suitable for vermicomposting; however, no difference could be found in the field. The worms seemed to survive well in the composts. The pH levels were similar to that of the initial pH, which could suggest that the pH stayed relatively stable in the compost. The temperature in the compost stayed close to that of the outside air temperature. The composts could have had been too dry for the worms, but there was a lot of organic matter present. The composts were well matured or under ideal curing.
Because of the short time period and the insufficient number of vermicomposts tested, no definite conclusions could be made. However, indications were seen during the project that there was potential for functioning vermicomposting in UD toilets in South Africa and that it would be of great interest to continue the studies further.
2015. , 34 p.