Using Polyphosphate Buffering to Treat Phosphorus-Deficient Wastewater

The suitability of the anaerobic/aerobic process was investigated for treating phosphorus-deficient wastewaters with highly variable influent chemical oxygen demand (COD) loading patterns to produce consistently low effluent P levels. During laboratory-scale experiments, two sequencing batch reactors (SBRs), one anaerobic/aerobic (AnA) and the other completely aerobic (CA), received transient influent COD loading patterns that simulated (No. 1) daily COD loading fluctuations and (No. 2) low weekend COD loading, each for a period of approximately 6  months. The AnA SBR produced lower effluent soluble P concentrations than the CA SBR during loading pattern No. 1 (0.5 versus 1.2  mgP/L). During loading pattern No. 2, both SBRs allowed effluent acetate breakthrough, following the low weekend COD loading period, and the P removal in the AnA SBR gradually deteriorated. The AnA process has the potential to produce lower effluent P levels than the CA process during transient loading periods due to the P release and uptake characteristics associated with the polyphosphateaccumulating metabolism. Extended periods of low COD loading can however cause a loss of P removal.