Nutrient removal from human urine by chemical precipitation

Several physico-chemical treatment methods such as membrane processes, air stripping, ion exchange, and electrochemical oxidation are addressed for the recovery of nutrients from source separated human urine, among them, chemical precipitation is a promising one since the nutrients are effectively transformed into solid phase which can directly be used as a fertilizer. Additionally, chemical precipitation for nutrient control using conventional precipitation agents such as iron, aluminum and calcium salts has been fully proven and commercially used treatment method for domestic and industrial wastewater. This method has also a potential to be used for separated human urine for nutrients, particularly phosphate removal. In the present study, the capabilities of conventional agents such as alum, ferric chloride and lime for the phosphate removal via chemical precipitation from human urine are experimentally investigated. Almost complete phosphorus removals were obtained at optimized operation conditions in the case of alum, ferric chloride and lime. All three precipitation agents yielded final phosphate concentrations less than 10 mgP/L.