Options for urine treatment in developing countries

Interesting prospects of a urine-based product exist as a fertilizer in agricultural applications in developing countries. However, removal of pharmaceutical residues is essential to prevent long-term environmental hazards. In this paper, the perspectives of urine collection and treatment are discussed with a perspective of the developing countries. Scenarios are drawn up and discussed around the processes of electrodialysis, precipitation and evaporation. A new process combination is presented consisting of nitrification in sand filters and solar evaporation, which could potentially be implemented in developing countries. Such a scenario enables good perspectives for local business development, which is an important prerequisite for the implementation of new technologies in the developing countries.

The global fertilizer and energy crisis calls for the development or alternative solutions for producing affordable nutrients which can sustain agricultural food production. New paradigm in waste processing is needed. In this paper, three processing unit for converting urine into fertilizer in the context of developing countries were discussed with regards to key sustainability criteria: fate of micropollutants, nutrient recovery, energy requirement and economic/business development potential. A scenario combining nitrification on sand-bed filters combined with solar evaporation was considered to be appropriate in areas close to agricultural zones (the market for the end product), also in cases where energy supply may be irregular or insufficient. It is expected that UV radiation and sun exposure in this case leads to hygienisation and removal of micropollutants in the final product. A second option consisting of struvite precipitation produces an effluent which requires an extensive wastewater treatment process. In view of the reaction stoechiometry, only 3% of N can be precipitated in struvite. Hence, the supernatant will still contain most of the nitrogen and micropollutants which are not removed by precipitation. The third scenario consists of electrodialysis, complemented by ozonation. It is effective in removing micropollutants hygienisation of final product, but the energy consumption is relatively large. Therefore, the economic viability of this option seems to be limited to large scale, centralized processing units, where a reliable and affordable power supply is available.