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Advanced treatment of tannery wastewater using the combination of UASB, SBR, electrochemical oxidation and BAF

Liu, Wei‐Hong, Zhang, Cheng‐Gui, Gao, Peng‐Fei, Liu, Heng, Song, Yan‐Qiu, Yang, Jian‐Fang
Journal of chemical technology and biotechnology 2017 v.92 no.3 pp. 588-597
ammonia, biodegradability, biofilters, chemical oxygen demand, chromium, ecotoxicology, electrochemistry, leather tanning, nitrogen, nitrogen content, operating costs, oxidation, sludge, tanneries, total suspended solids, upflow anaerobic sludge blanket reactor, wastewater, China
BACKGROUND: Wastewater discharged from tannery industries is highly complex, concentrated, and toxic. In view of the varying nature of discharged wastewater and the numerous small industries in China, there is a need for highly efficient treatment processes that are simple to operate and have low/reasonable construction and operating costs. RESULTS: An integrated process of upflow anaerobic sludge bed (UASB) – sequencing batch reactor (SBR) – electrochemical oxidation (EO) – biological aerated filter (BAF) was developed at lab scale for the treatment of tannery wastewater with an initial chemical oxygen demand (COD) of 8300–9250 mg L⁻¹. The results show that, under the optimum conditions, the efficiency of removal of COD, total suspended solids, total nitrogen, ammonia, oil‐grease, S² ⁻, total Cr and Cr⁶⁺ was more than 90%, and the quality of the final effluent met the national discharge standard of China set for the leather tanning industry. The UASB process removed a considerable proportion of easily degradable organics and improved the biodegradability of the wastewater, while the SBR played an important role in the removal of nitrogen and residual COD. The EO process further enhanced the biodegradability of the SBR effluent, and finally, post‐polish treatment was accomplished in the BAF. The ecotoxicity of the wastewater was remarkably reduced after undergoing the hybrid treatment. CONCLUSION: This work demonstrates that the hybrid system has the potential to be used for the advanced treatment of high‐strength tannery wastewater. © 2016 Society of Chemical Industry