Effect of aeration rates on the performance of an OSA-based sludge reduction process: limitations and implications

Abstract

The oxic-settling-anaerobic (OSA) process can decrease the amount of sludge generated during wastewater treatment. In this study, the effect of aeration rates on the performance of an OSA-based sludge reduction process was investigated. Aeration rates did not significantly impact on sludge reduction in the main reactor (44.5% reduction at the lower aeration versus 45.4% reduction at the higher aeration rate). Integrating a side reactor for hydrolysis/acidification did not affect effluent quality, but resulted in slightly greater dominance of Proteobacteria and Dechloromona in the main wastewater treatment reactor, especially under the low aeration. Recycling anaerobic hydrolysate improved denitrification, while nitrification was unaffected. However, recycling the anaerobic hydrolysate decreased sludge settle ability under the low aeration. These results have implications for operating and optimizing an OSA process for sludge reduction.