Many effluent standards are approaching values of 0.01 to 0.02 mgP L-1 to prevent eutrophication of surface waters. Enhanced biological phosphorus removal (EBPR) is used extensively with removals resulting in effluent concentrations ranging from 1-5 mgP L-1, requiring chemical treatment to meet stricter standards. EBPR also often proves to be unstable and unreliable. This study will advance a new metabolic model for EBPR that proposes the process is driven by the microbial stringent response that results from unbalanced growth conditions within wastewater treatment. By maximizing the extent and duration of the stringent response, effluent concentrations can be reduced to 0.01 to 0.02 mgP L-1. The study will be undertaken through four discrete tasks. Under Task 1 we will confirm the critical metabolic processes associated with the proposed EBPR-Stringent Response model through multivariate statistical analyses of time-series proteomics data derived from laboratory-scale bioreactors operated with real wastewater and wild microbial consortia. Tasks 2 and 3 will establish the optimum reactor operational parameters within biological wastewater treatment wherein the indigenous microbial consortium will accomplish biological phosphorus removal to negligible levels while concurrently accomplishing all other biological treatment objectives. Task 4 will develop design and operational criteria for process scale-up. The new understanding of the microbial stringent response will result in more sustainable wastewater treatment with decreased demand for chemicals, less capital and operations costs, and prevention of long-term problems with biosolids treatment.
