Sludge treatment

Septic tank systems for wastewater treatment can be found all over the town. Anyway, despite a huge need for sludge emptying and disposal no means to provide these services were existing. Within ROSA a sludge drying bed was constructed but not operational due to several technical and organisational reasons. As basis for further work on sludge treatment, the sludge drying bed was put into operation during the fall meeting 2012. The maintenance works included fence work to prevent access of animals and unauthorized persons, the removal of the top layer of the beds to ensure treatment volume and the provision of road access for transport by truck (pictures below).


The further work comprised the monitoring and optimization of septic tank emptying and the transport to the facility as well as the treatment itself. Quantitative and qualitative analyses followed and also an economic analyses was carried out. Based on the calculations and the experience the partners in CLARA have gathered, it was concluded that the option of building more sludge drying beds in the town of Arba Minch is not sustainable so far. This is due to the high operation and maintenance costs that would be summed if the number of functioning beds arises to cover significant areas of the town. However, following the business plan conducted, the two current sludge drying beds will keep operating and be used also in future. On the other hand, there exists a big potential for co-composting of the town sludge and solid waste. Dried sludge from the town sludge drying bed, dried faecal matter from the town urine diverting dehydrating toilets, and the organic solid waste from the town could be put together and then be composted. The compost could be marketed to the peri-urban farmers or used in tree seedlings. The full final report can be downloaded here.