Assessment of Chemical Oxygen Demand Removal Efficiency and Microbial Dynamics during Aerobically Degradation of Wastewater in Activated Sludge

Abstract

<p>This study investigated aerobically COD removal and microbial dynamics during activated sludge treatment of wastewater. The 12-day experiment utilized descriptive analysis to correlate operational parameters of pH, F/M ratio, MLSS, and SVI with COD removal efficiency. Microscopic examination identified temporal shifts in abundances of bacterial flocs, flagellates, ciliates, and rotifers. COD removal declined from 79% on day 0 to 4% by day 12, corresponding with increased SVI and protozoan proliferation. High SVI caused biomass washout, reducing bacterial catabolic capacity. Predominance of bacterivorous protozoa and rotifers likely suppressed floc-forming bacteria responsible for COD biodegradation. Conserving balanced mixed communities through optimized operational conditions appears decisive for continuous treatment performance. This study provides comprehensions on microbial ecological interactions altering temporal variability in activated sludge COD removal.</p>