零价铁还原协同微生物降解处理化工废水的研究

Study on degradation of chemical wastewater by zero-valent iron combined with microorganism

针对某工园区综合化工废水的水质特征,拟将零价铁（ZVI）还原与厌氧折板反应器（ABR）、前置反硝化（A/O）工艺耦合对其进行处理,考察了系统的运行效果,并对废水中的特征污染物——对氯硝基苯的降解性能进行了分析.结果表明,ZVI预处理后化工废水中残留的对氯硝基苯在ABR中厌氧微生物作用后得到进一步降解,且在ABR处理过程中COD去除率较单独ZVI或微生物作用时大幅提高,虽然ZVI对难降解有机物无矿化作用,但可将难降解有机物转化为毒性较小的有机物,明显改善废水的生化性;通过控制合适的混合液回流比、有效补充碳源和碱度,可以提高A/O系统的运行效率;在较佳的工况（ABR系统HRT为24 h,A/O池污泥回流比为100％、混合液回流比为3∶1,碳源投加量为3.5 g）下运行连续2个月,整个系统的COD平均去除率在90％以上,出水COD质量浓度基本低于100 mg/L,NH3-N去除率在80％～90％,出水NH3-N质量浓度在20 mg/L以下,出水对氯硝基苯、对氯苯胺质量浓度分别在0.58～4.08、0.68～5.88 mg/L,出水水质符合《江苏省化学工业主要水污染物排放标准》（DB32/939-2006）.

AcCording to the characteristics of wastewater from chemical industries of an industrial park,the com- bined process of zero-valent iron （ZVI） reduction, Anaerobic Baffled Reactor （ABR）,and prepositive denitrification A/O was put forward to get the stable effluent qualities. The overall operation efficiency of combined process was in- vestigated and the degradation of particular pollutant （p-chloronitrobenzene） was studied. Results showed that large amount of p-chloronitrobenzene was removed during the ZVI pretreatment process,after then the residue p-chloroni- trobenzene was further degraded by anaerobic microbes in ABR. Although ZVI pretreatment had no mineralization effect to refractory organic matter, it could transform these refractory organic matters into lower toxicity organic com- pounds,obviously improve the biochemical degradability of wastewater and finally increase the COD removal efficiency of ABR process. The appropriate reflux ratio, carbon source supplement and basicity could effectively improve the treatment efficiency of A/O system. The optimum operating conditions were obtained as follow., hydraulic retention time （HRT）of ABR was 24 h,sludge return ratio of A/O system was 100% ,mixed-liquor return ratio was 3 ： 1 ,and carbon source supplement was 3.5 g. Under these optimal conditions,the established combination process was opera- ted for 2 months, the average COD removal rate reached more than 90 % with effluent COD was lower than 100 rag/L, average NH3-N removal rate ranged 80%-90 % and effluent NH3-N was lower than 20 mg/L. Besides,the concentra- tions of p-chloronitrobenzene and p-chloroaniline in effluent were 0.58-4.08 and 0.68-5.88 mg/L respectively. The effluent water quality conforms to the major water pollutant discharge standard of chemical industry in Jiangsu Prov- ince （DB 32/939-2006）.