Nutrient recovery by struvite precipitation, ion exchange and adsorption from source-separated human urine–a review

The control of nutrients is a priority issue to protect drinking water resources as well as other water bodies. Although this control can be ensured through well designed joint treatment systems in cities, its application in rural areas is not as technically feasible. Therefore, the concept of decentralized treatment and source separation of domestic wastewater has been developed as a result of this requirement. This concept includes, not only control of nutrients, but also recovery and reuse of nutrients mainly for agricultural purposes. Among the source-separated fractions of domestic wastewaters, human urine or yellow water is of importance since it collects a significant part of all nutrients in a small volume. Therefore, studies have been focused on nutrient recovery from source separated human urine. This review evaluates the present state of urine treatment and resource recovery using struvite precipitation, ion exchange with zeolites and adsorption processes. The evaluation of these processes has been made by considering their theoretical bases, operational parameters, efficiencies, advantages and disadvantages. Coupling of these treatment and recovery processes with newly developed technologies such as electrochemical and biological means were considered. The impact of the use of these technologies on the environment was also evaluated. Further need of research for all processes has also been assessed and emphasized.