Valorisation of Urine Nutrients in Africa (VUNA) /Promoting sanitation and nutrient recovery through urine separation (RN88)
Funded by: Bill & Melinda Gates Foundation
Subcontract through the EAWAG
November 2010 – August 2014
Partner organisations: EAWAG; eThekwini Water and Sanitation
Project background
The VUNA project is a multi-disciplinary collaborative project funded by the Bill & Melinda Gates Foundation to undertake research into the collection and processing of urine from urine diversion dry toilets (UDDTs). The aim of the project is to recover the nutrients present in urine to produce fertilizer. EAWAG, the Swiss Federal Institute of Aquatic Science and Technology, is the lead organisation on this project, with the University of KwaZulu-Natal (Pollution Research Group, PRG) and eThekwini Water and Sanitation (EWS) as project partners.
The VUNA project is guided by three concepts:
- Separation at the source: Waste streams with different compositions, for example urine and faeces should be treated separately according to their properties.
- Decentralization: The waste streams should be treated as closely to the source as possible, thereby minimizing the water and energy required for transportation.
- Resource recovery: Treatment should focus on recovering the resources contained in the waste streams. Urine is a concentrated nutrient solution, which can be converted into a fertilizer, while faeces contain energy-rich organic substances.
The project involves several major components carried out by the different partners. The first major component of the project involves developing and optimizing reactors for urine treatment and nutrient recovery. Two reactor setups are being tested: a struvite reactor and a combination of nitrification and evaporation reactor. The reactors will be installed in the communities that have been selected as study sites for urine collection and treatment. These reactors process urine that is collected from communities using UDDTs and recover phosphorous and other nutrients that are important as fertilizers.
The second major component, Network Management, involves establishing the logistics for the collection and transport of urine from the households to the treatment, and developing a software program to monitor field data on the number, size and performance of reactors required to recover the most nutrients at the lowest costs.
The third component examines the socio-economic aspects of scaling up this type of work into a sustainable sanitation management process. When implementing a new sanitation system the needs of the community (public health, financial considerations, environmental protection, nutrient recovery) and the preferences of the users have to be well balanced.
The final component examines the socio-economic factors that influence the willingness of households to use the UDDTs and collect and bring their urine to collection sites within their communities. One study under this component is investigating the economic feasibility of household urine collection. Two other studies focus on the social, cultural, and political factors influencing user acceptance of UDDT, urine collection and nutrient recycling.
The VUNA project is currently in its third year. To date, several reactors have been constructed and optimized for processing urine from selected communities in eThekwini and recovering nutrients. The struvite reactor recovers more than 91% of the total phosphorus found in the urine. Two other reactors have been built to recover all nutrients present in urine (e.g. potassium, nitrogen, and phosphorous). A nitrification reactor has been manufactured to biologically stabilize urine, while an evaporation reactor has been constructed to remove most of the remaining water and produce a concentrated solution containing multiple nutrients (e.g. potassium, nitrogen and phosphorus). The solution can be processed further into powder form having a valuable fertiliser applicable in the field. A 40 litre manually operated struvite reactor has been set up at the Newlands Mashu treatment plant. The nutrient rich fertilizers are being employed in a separately funded investigation that is testing the agricultural benefits of the fertilizer on crop growth.
The two social acceptance studies are underway, being undertaken by two members of EWS who are completing masters degrees at UKZN. Over 17 000 households in eThekwini have been surveyed regarding the introduction of urine diversion dry toilets. This data is being analysed and a follow up survey is being developed to assess changes in acceptance over time. In addition, another study is examining the influence of health and hygiene education on social acceptance, utilisation and maintenance of UDDTs.
Publications and reports
- Grau, M. Etter, B., Udert, K.M., Brouckaert, C.J., Buckley, C.A. 2012. Development and operation of struvite reactors to recover phosphorus from source separated urine in eThekwini. Paper prepared for WISA Biannual Conference, Cape Town, May 2012.
- Grau, M., Etter, B., Hug, A., Wächter, M., Udert, K.M., Brouckaert, C.J., and Buckley, C.A. 2012. Nutrient Recovery from Urine: Operation and optimization of reactors in eThekwini. Presentation to the 2nd Annual International Faecal Sludge Management Conference. Durban, October 2012.
- Grau, M., Rhoton, S., Brouckaert, C.J., and Buckley, C.A. 2013. Development of a Fully Automated Struvite Reactor to Recover Phosphorus from Source Separated Urine Collected at Urine Diversion Toilets in eThekwini. Paper presented at the WEF/IWA Nutrient Removal and Recovery Conference. Vancouver, British Colombia, July 2013.