SOURCE SEPARATION OF URINE AS AN ALTERNATIVE SOLUTION TO NUTRIENT MANAGEMENT IN WASTEWATER TREATMENT PLANTS: A MODEL-BASED ANALYSIS

摘要

Municipal wastewater contains a mixture of brown (feces and toilet paper), yellow (urine) andrngray (kitchen, bathroom and wash) waters. Urine contributes approximately 70-80% of thernnitrogen (N), 50-70% of the phosphate (P) load and 60-70% of the pharmaceutical residues inrnnormal domestic sewage. This study evaluated the relative effects of source separation of urinernon an existing BNR process. A calibrated model of an existing state-of-the-art biological nutrientrnremoval process was used. It was found that by increasing the amount of urine diverted out ofrntreatment works, an improvement in effluent ammonia concentration and a reduction in thernsludge age requirements were not obtained. Furthermore, little benefits could be realized unlessrnenough urine is diverted out of treatment facilities so the influent N can be reduced to low valuesrnto allow the elimination of nitrification. Lower effluent nitrate concentrations were realized duernto the lower influent N content in the wastewater and a more favorable TKN/COD ratio forrndenitrification. The external carbon requirement for denitrification decreases as the urinernseparation efficiency increases due to the lower influent N content in the wastewater and a morernfavorable TKN/COD ratio for denitrification. The effluent phosphorus concentration decreasesrnwith reducing the amount of urine to treatment works due to the lower influent P concentrations.rnIn the case of chemical phosphate removal, urine separation reduces the amount of chemicalsrnrequired.