IMPORTANCE OF AEROBIC UPTAKE IN OPTIMIZING BIOLOGICAL PHOSPHORUS REMOVAL

In recent years, there has been a significant increase in the number of utilities using biological phosphorus removal (BPR) to remove phosphorus (P) from municipal wastewaters. The basic BPR mechanism includes two distinct steps: anaerobic P release, and aerobic P uptake. However, BPR design and optimization efforts have typically focused on the anaerobic release step of the process, with a lot of attention being paid to maximizing anaerobic P-release through augmentation with volatile fatty acids (VFAs) and by minimizing interferences from nitrate and dissolved oxygen. In contrast, there is little published work, especially from full-scale wastewater plants, on optimization of the aerobic uptake step of the BPR process. This paper presents results highlighting the importance of the aerobic uptake step in the BPR process, based on full-scale experimentation conducted at Clean Water Services' Durham Advanced Wastewater Treatment Facility (Durham AWTF). Comprehensive side-by-side sampling and profiling was conducted on four different reactor configurations in 2005 as part of a BPR optimization study. A major outcome of this study was an improved understanding of the importance of aerobic uptake in BPR. Aerobic uptake was found to be the critical step limiting process performance, with the P uptake in the initial aerobic zones having a particularly significant impact on BPR performance.