Stability of pure oxygen aeration-activated sludge system under non-steady food-to-microorganism ratio conditions during petrochemical wastewater treatment

摘要

This study investigates the stability of a pure oxygen aeration-activated sludge system for petrochemical wastewater treatment under high organic concentration and non-steady food-to-microorganism (F/M) ratio conditions. Sludge settling characteristics maintained relatively stable conditions with an F/M ratio variation from 0.15 +/- 0.04 to 0.33 +/- 0.07 kg COD/kg MLSS.d, while the excess F/M ratio (0.44 +/- 0.16 kg COD/kg MLSS.d) resulted in deterioration of the organic removal and sludge-water separation performances. Loosely bound extracellular polymeric substances (EPS) showed more significant effect on sludge settleability than the tightly bound EPS. The genusHydrogenophagawas related to organic removal performance, whileZoogloeaandChitinophagawere related to the effluent quality of suspended solids. The excess F/M ratio also caused an increase inZoogloeaandChitinophaga, whereas the toxicity of petrochemical wastewater resulted in decreased abundance ofHydrogenophaga. These changes caused deterioration of the organic removal and sludge-water separation performances.