A/O-MBR在冷轧含油废水处理中的应用OACHSSCDCSTPCD

In the steel rolling production process,a considerable amount of wastewater is generated.Direct discharge of them would not only pollute the environment,but also cause a substantial waste of water resources.This study employed an anaerobic/aerobic-membrane bioreactor(A/O-MBR)pilot equipment and custom-made braid reinforced polyvinylidene difluoride(PVDF)membrane modules for steel rolling wastewater treatment at a steel company in Nanjing.The objective is compliant discharge of steel rolling wastewater.The experiment showed that the waste water treatment achieved a turbidity removal rate above 99％,a chemical oxygen demand(COD)removal rate over 90％,and a mineral oil removal rate above 80％.The treated water's turbidity,COD and oil contents were reduced to below 0.2 NTU,50 mg/L,and 4.5 mg/L,respectively.When operated stably below subcritical flux for about 250 hours,the transmembrane pressure difference(TMP)of the membrane modules increased rapidly and reacheded the limit of 30 kPa,indicating the upper threshold of membrane capacity.The analysis of membrane fouling resistance showed that the main fouling type was filter cake layer fouling,which could be removed by simple water washing.In addition,a significant proportion of membrane pore blockage fouling,greatly contributing to irreversible fouling and the rapid TMP increase in the later stage of the pilot test,was identified.The mineral oil content in steel rolling wastewater aggravated membrane fouling and optimal results were obtained after periodic backwashing with low-concentration of sodium hypochlorite.