Composting and urine conditioning

Within ROSA several types of toilets that allow reuse (e.g. UDDTs and fossa alternas) have been constructed in private houses, institutions and schools. These facilites are still in operation and the basis of the work within CLARA. Transport of urine and faeces is done by solid waste collectors. AMU researches urine conditioning methods (production of struvite from urine) which reduce problems in handling urine (e.g. large volume and nitrogen loss). Knowledge exchange with the South African colleagues is going on: The AMU team leader visited Durban to learn from their practical experiances on urine conditioning in the Ethekwini muncipality (left picture below). During the last meeting, a stakeholder day was organized to explain the idea of struvite based fertilizer production to local farmers (right picture below).

durban2_small struvite1_samll

Faeces are transported to ENM for co-composting.Hence, beside the efforts to produce an affordable fertilizer from urine, improvements for co-composting are under investigation at the site of ENM to improve the output. Composting drums (picture below) and vermi composting are tested.

composting1_small

Urine conditioning and struvite precepitation were furher investigated in Arba Minch. Social acceptance of struvite was found to be good. Source separated urine from
UDDTs is a potential source of nutrients so as to be used as a substituent of commercial fertilizer. However, collection, storage and transportation of urine are significant problem in Arba Minch. However, assessments and calculations showed that magnesium oxide obtained from local market would be a cheaper magnesium source relative to the other sources. A filter bag made from locally available material was capable of removing over 60% of phosphorus without filtering. A micro tube drip irrigation system was used to supply water for all trials. Investment and operating cost of struvite precipitation was found to be as high as the struvite price estimated using the nutrient value analysis of locally available chemical fertilizers. Therefore, the economic analysis without considering the external benefits revealed that the local potential in Arba Minch is nopt favorable for this technological option. However, emphasis should be given on the availability of a non-renewable resource and the reduction of  environmental impacts, i.e. state or other actors should willingly subsidize its production so that it would be competitive on the local market. The full final report on urine conditioning can be downloaded here.