Impact of excessive aeration on biological phosphorus removal from wastewater

The effect of excessive aeration on biological phosphorus removal (BPR) processes is studied using a laboratory anaerobic-aerobic-settling sequencing batch reactor. It is demonstrated that the phosphorus uptake stops due to a gradual depletion of poly-hydroxy-butyrate (PHB) in an over-aerated process. If organic substrate is introduced to the system, phosphorus release is immediately at its maximal rate. However, the released phosphorus cannot be taken-up fully again because PHB content limits the uptake rate. Consequently, incomplete phosphorus uptake leads to temporary reduction of BPR efficiency. This causal effect can explain the deterioration of BPR efficiency after heavy rainfall.