Excreta and Wastewater ManagementVUNA Harvesting Nutrients from Urine - PDF document

1 Excreta and Wastewater ManagementVUNA: H
Excreta and Wastewater ManagementVUNA: Harvesting Nutrients from Urine for Agriculture VUNA is a trans-disciplinary project that is developing a system to collect source-separated urine and process it into fertiliser. Collection logistics, treatment technologies, and social and economic assessments of nutrient recovery are some of the activities worked on by the VUNA team. Bastian Etter, Teddy Gounden Agricultural UseRisks of Urine UsageUrine Collection NetworksSocio-economic Nutrient Recovery Eawag_08343 11 Sandec News 15 / 2014 Figure 2: The nitrification and distillation process converting source-separated urine into distilled water and fertiliser.[1] Etter, B., Gounden, T., Udert, K.M. (2014): VUNA … Scaling Up Nutrient Recovery from Urine. International Conference on Technolo-gies for Development. 4 … 6 June, EPFL, Lausanne, Switzerland.[2] Joseph, H., Gebauer, H., Friedrich, E., Buck-ley, C.A. (2014): Institutionalised collection for rural on- site sanitation. WISA Biennial Conference and Exhibition, 25 … 28 May, Mbombela, South Africa.[3] Udert, K.M., Buckley, C.A., Wächter, M., McArdell, C.S., Kohn, T., Strande, L., Zöllig, H., Hug, A., Oberson, A., Etter, B. (2014): Technologies for the treatment of source- separated urine in the South African munici-pality eThekwini. WISA Biennial Conference and Exhibition, 25 … 28 May, Mbombela, Eawag/Process Engineering, Switzerland eThekwini Water and Sanitation, Durban, South AfricaThe authors would like to thank the entire The VUNA Project is funded by the Bill & ployees in urine - diverting toilets into fertil- iser, and the second is at a field trial site in eThekwini (See Figure 2). Nitrification and distillation is a two -step process, which first stabilises the nitrogen in urine in a biologi-cal process (nitrification), and then evapo-rates the liquid (distillation) in order to obtain a concentrated nutrient solution. Distilled water is issued from the process Struvite precipitation was tested in the field in eThekwini. This process is simple in op-eration, but recovers mainly phosphorus (90 %) and a small fraction of nitrogen (less than 5 %). Magnesium is used as precipi-tant and the produced struvite is recovered from the liquid via filtration. In further

2 trials, Eawag researchers also investiga
trials, Eawag researchers also investigated elec-trochemical treatment of urine. Becauseurine electrolysis cells are small in size and might fit into individual toilets, this could enable on - site treatment. However, search is still at an initial stage and further efforts are required to bring the technology The studies on hygienisation and the remov-al of trace organic substances show that ni-trification inactivates certain bacteria and extent. The distillation step after nitrification ensures that all remaining pathogens are killed. Any remaining pharmaceuticals can be removed with granulated activated car-bon, if necessary, due to regulatory require-ments. In agricultural tests, the urine - derived fertilisers performed equally or even better than conventional synthetic fertilisers. Evaluating acceptance Previous studies have shown that the initial acceptance of UDDTs in eThekwini was low. Increasing their acceptance by giving urine a value is one of the VUNA Project goals. To this end, an education programme on UDDTs is being developed to foster an un-derstanding of the benefits of sanitation in general and of UDDTs in particular, and chang-es in perception and behaviour are being as-sessed by questionnaire - based surveys Preliminary results and experiences gath-cate that people started using their toilets more frequently when they realised that their urine was collected to produce fertilis-er. Although urine is not traditionally used as a fertiliser for agriculture in eThekwini, toilet users did not disapprove of eating crops fer-tilised with urine - derived products. Business models have been developed for the VUNA processes, from urine collection to the final fertiliser product. The business mod-els give an integrated overview of the most viable options for a sanitation system based on urine source - separation in eThekwini. Conclusion collection and treatment processes to serve a larger part of the population. Before collec-tion can be taken to full scale, however, an-the exact modalities. Similarly, although the treatment processes have proven to be functional, further research is necessary to make them more robust and user - friendly. The VUNA team is currently in contact with necessary for future research