Effect of Variable Influent Phosphorus Loads and Internal Returns on Biological Phosphorus Removal, A Case Study

The objective of this study is to determine the effects of variable phosphorus load in influent and recycled stream on biological phosphorus removal with the uncertainty of predictions using process modeling and a Monte Carlo method. First, a process model was developed to simulate the biological phosphorus removal process for the Camp Creek WRF in Georgia. Then the model was calibrated by measuring critical parameters that determine the performance of nitrogen and phosphorus removal. Alternative operational strategies were evaluated to improve the plant operation and minimize chemical uses for phosphorus removal. In addition, the process model was integrated with the Monte Carlo approach to investigate the uncertainties of recycled stream effect on phosphorus removal at the plant. Advanced Continuous Simulation Language (ACSL) was used to incorporate the Monte Carlo method into the process model. Each model input of phosphorus load was characterized as a random variable with a Gaussian distribution. The modeling results showed that the probability for the effluent total phosphorus concentration below 0.3 mg/L was 31% with the effect of recycled stream, while the probability increased to 84% without the effect of recycled stream.