Integration of Processes to Treat Wastewater and Source-Separated Urine

Human urine contributes 80% of the total nitrogen and 40–50% of the total phosphate load to municipal wastewater. This study examines the impact of separate urine collection and treatment on wastewater treatment. An integrated wastewater and urine treatment process was defined, in which single high-rate ammonium removal over nitrite and anaerobic ammonium oxidation processes and struvite recovery are at the heart of the nutrient management. The model study demonstrated that if 50% or more of urine were collected and treated separately, integrated wastewater treatment with more compact and energy-efficient processes would be possible. The integrated wastewater and urine treatment is compared to an existing state-of-the-art treatment process. The main advantage of urine separation is not only a better effluent quality. Existing processes including tertiary treatment can already produce very good effluent quality with total effluent nitrogen and phosphate concentrations of 2.5 and 0.5 g/m3, respectively. The main advantage of urine separation is the production of this same good effluent quality with a remarkable saving in resources. With sufficient urine separation, generation of net primary energy is possible.