Performance of a novel HABR–CFASR system for the biological treatment of mixed printing and dyeing wastewater (MPDW)

Abstract

Mixed printing and dyeing wastewater (MPDW) is characterized by a low-strength chemical oxygen demand (COD; average of around 1,000 mg/L), a high fraction of recalcitrant components, a low COD/ ratio (approximately 1.0), and a high pH (about 8–10 without adjustment). In this study, a biological system that combined a hybrid anaerobic baffled reactor (HABR) and a cross flow aerobic sludge reactor (CFASR) was successfully used to treat MPDW that was discharged from an industrial zone. The HABR–CFASR system was fed with real MPDW. In the start-up stage, the system had low organic loading rates of 0.66 and 0.45 kg COD/(m³·d) for the HABR and CFASR, respectively. These increased to 2.03 and 1.00 kgCOD/(m³·d), respectively, in the steady stage. The pH of the HABR influent was reduced by adding H₂SO₄ at a decreased dosage over the course of the experiment. Most of the final effluent from the combined treatment process was stable below 100 mg-COD/L and 20 mg-BOD/L after 12 h-HRT in the HABR followed by 20 h in the CFASR. The sulfate removal rate reached 17.59%, and the COD/ ratio varied slightly around 1.0, regardless of the Ns (sulfate loading rate), which varied between 1.5 and 2.5 kg/(m³·d). A GC/MS analysis demonstrated that the amount and types of organic compounds declined significantly after the HABR treatment.

Keywords:

• Mixed printing and dyeing wastewater (MPDW)
• Hybrid anaerobic baffled reactor (HABR)
• Cross flow aerobic sludge reactor (CFASR)
• Sulfate reduction

Acknowledgments

This study was supported by the National Natural Science Foundation of China (Nos 51208131, 51278088, and 50908062) and the State Key Laboratory of Urban Water Resource and Environment (No. HIT-QAK201103) also supported by National Science and Technology Major Project of China (No. 2012ZX07201003 and No. 2014ZX07204-005) and The National Twelfth Five-year Science and Technology Support Project (No. 2013BAJ12B02). The authors are grateful to the Research Center of Environmental Biotechnology at the Harbin Institute of Technology for its technical and logistic assistance.