Intricacies of Enhanced Biological Phosphorus Removal in Full-Scale Sequencing Batch Reactors Based on Wastewater Treatment Plants of India

Enhanced biological phosphorus removal (EBPR) is a growing, succeeding, and recognized process for removing phosphorus biologically from wastewater. Four sequencing batch reactor (SBR) plants with capacities of 120, 87.5, 50, and 3 million L per day (MLD) from different Indian locations were analyzed for EBPR. The 120 MLD Varanasi, 87.5 MLD Mumbai, and 50 MLD Gurgaon plants were working effectively for EBPR; >75% total phosphorus (TP) removal was observed at milligrams of readily biodegradable chemical oxygen demand (rbCOD) per milligram TPremoved of 12.0, 14.4, and 18.6, respectively; however, the 3 MLD Roorkee SBR was working mainly as adequate nitrogen removing technology at milligrams rbCOD/mg TPremoved<8. The linear increasing trend was observed between rbCOD/COD (%) and EBPR (%) at R2=0.99 (p<0.05 and r=0.99) in plants. Optical microscopic examinations were performed to identify the intracellular polymers [poly-β-hydroxybutyrate (PHB) and polyphosphates] in the EBPR sludge. This study focuses on optimizing the SBR designs (selector and non-selector based) for EBPR and identifying the relationships between wastewater characteristics and phosphorus removal governed by typical microbial functions with the perspective of optimizing decentralized treatment systems of India.