Biological nutrient removal in high salinity wastewaters

Abstract

The effect of a saline wastewater on the performance of a biological nutrient removal system was investigated using a model A²/O activated sludge system. The system was operated at a 13 day sludge age with a salinity level of 4,000 mg/l and compared with a similarly operated system with a salinity level of 200 mg/l. Mass balance calculations and the student t‐test were used for data analysis. It was found that a COD removal efficiency of 90 percent can be achieved when treating wastewater having an influent salinity of 4,000 mg/l. Nitrogen could be removed from the saline wastewater with the same efficiency as for the nonsaline wastewater. Excess biological phosphorus removal efficiency decreased from 82 percent to 25 percent at salinity levels of 200 and 4,000 mg/l, respectively.