Study On Treatment Technology Of2,4-dinitrochlorobenzene (DNCB) By Internal-electrolysis Reduction Of Catalytic Iron Integrated With Bioaugmentation

2,4-dinitrochlorobenzene (DNCB) is an important chemical widely used in the fields of dyes, pesticides, pharmaceuticals and explosives. The chemical is chemically stable and has carcinogenesis, teraogenesis, mutagenesis and genotoxicity, which is listed as priority control toxic biorefractory organic pollutant in our country. This papers aimed to treatment of2,4-dinitrochlorobenzene. Integrated precess consisted of internal-electrolysis reduction of catalytic iron and bioaugmentation treatment was design. Zero-valent iron (ZVI) reduction/anaerobic baffled reactor (ABR)/moving bed biological the membrane reactor (MBBR) process was tested at bench scale. Focus was on the pretreatment technology of catalytic iron internal-electrolysis, degradation pathway of DNCB by the combined process and evaluation of the integrated process for the simulated wastewater.Study on catalytic iron internal-electrolysis pretreatment indicated that DNCB removal rate was as high as95.0%at the condition of copper loading rate of0.20%, hydraulic retention time of6h, weak aeration, DNCB initial concentration200mg.L-After pretreatment by catalytic iron internal-electrolysis process, BOD5/COD increased from0.005±0.001to0.168±0.007; EC50,48h (V/V) increased from0.65%to5.20%. Biodegradability of simulated wastewater was greatly enhanced, while acute toxicity decreased greatly.Study on degradation mechanism of DNCB by "ZVI-ABR-MBBR" integrated process indicated that in the catalytic iron inner electrolysis system, nitro group on DNCB was degraded into amino group, generating2,4-diaminochlorobenzene (DACB). However, further dechlorination reaction of DACB was not observed in the ZVI system. In the ABR reactor, DACB could be reductively dechlorinated using methanol as the electron donor, with m-phenylenediamine as product. Generated m-phenylenediamine could be degraded and mineralized completely in the subsequent anaerobic and aerobic process.Study on DNCB simulated wastewater treatment by "ZVI-ABR-MBBR" integrated process indicated at ZVI hydraulic retention time of6h, ABR hydraulic retention time of7days, MBBR hydraulic retention time of3.5days, the methanol dosage of750mg.L-1, DNCB initial concentration200mg.L-1, after treatment of "ZVI-ABR-MBBR" integrated process, the effluent COD was less than35mg.L-1, TOC was less than22 mg.L-1. Significant accumulation of intermediates was not observed.Effective reduction of chloronitrobenzene pollutantant could be achieved by catalytic iron internal-electrolytic reduction system, with biodegradability of wastewater improved and toxicity reduced. Further degradation of reductive products could be achieved in subsequent bioaugmentation treatment process, ensuring high quality of effluent. For the treatment of chloronitrobenzene containing wastewater, internal-electrolysis reduction of catalytic iron integrated with bioaugmentation was feasible.