Biological nutrient removal from a phosphorus-rich pre-fermented industrial wastewater

Abstract
The objective of this work was to demonstrate the feasibility and to quantify the maximum extent of enhanced biological phosphorus (bio-P) removal from a phosphorus-rich (60 to 100 mg P/L) wastewater originating from a cheese factory (2100 mg total COD/L; 57 mg total TKN-N/L). An existing wastewater treatment plant at the industrial site consisted of an anaerobic equalization tank followed by an anaerobic upflow sludge blanket (UASB) and aerated lagoons. In a bench-scale sequencing batch reactor, bio-P removal was better achieved by treating the effluent from the equalization tank in which a high level of volatile fatty acids were produced (1230 mg as HAc/L) rather than the effluent from the UASB. The effluent orthophosphates concentration reached as low as 5 mg P/L. An intracellular polyphosphates content in the biomass greater than 5% (g P/g MLVSS) was observed which demonstrated without doubt that bio-P removal, and not just normal metabolic phosphorus accumulation, took place. Optimizing industrial bio-P removal should consider prior acidogenesis of the influent wastewater, acetate or chemical addition, and an efficient control over effluent suspended solids.