The effect of phosphorus on phosphorus metabolism, metals accumulation and floc properties in activated sludge processes

The influence of phosphorus levels in the activated sludge treatment process with respect to reactor performance, phosphorus metabolism, floc properties and metals accumulation was studied using a laboratory sequencing batch reactor system fed a simulated photographic chemical manufacturing wastewater. The phosphorus loadings applied to the biomass in this study ranged from a COD/N/P ratio of 100/5/1 (phosphorus-rich) to 100/5/0.05 (phosphorus-poor). The range of phosphorus loadings applied to the biomass did not significantly impact on reactor performance in terms of COD removal and SVI. The biomass demonstrated the ability to store intracellular and extracellular phosphorus reserves under the phosphorus-rich loading. The biomass demonstrated the ability to utilize these phosphorus reserves under the phosphorus-poor loading through a significant increase in phosphatase activity compared to the phosphorus-rich loading. A moderate increase in silver accumulation in the biomass was observed under the phosphorus-poor loading versus the phosphorus-rich loading.