Enhanced biological treatment of avermectin fermentation wastewater combined with physiochemical pretreatment

摘要

This paper aimed at the development of enhanced biological treatment process for the avermectin fermentation wastewater (AFW) after the UASB treatment by combining the physicochemical pretreatment and biological treatment approaches. After the pretreatment of the UASB-treated water using coagulation, the pretreated wastewater was subsequently flowed into a rCAA (reactor with repeatedly coupling of aerobes and anaerobes using macroporous carriers) system for further pollutant degradation and excess sludge reduction. By the chemical coagulation, COD, total N and total P in the UASB-treated water could be eliminated to 550-650 mg/L, 130-160 mg/L, 1 mg/L, respectively, and the dark color of the water was reduced to a low level. The toxicity experiment indicated that AFW had serious inhibition to the microbes in rCAA. The Bio-log and OUR test showed that the residual chemicals after the biological treatment showed low microbial degradability, which would be the key affecting factor for reducing the COD further in AFW.