Pilot-scale study on an advanced Fe-Cu process for refractory wastewater pretreatment

Jin-Hong Fan; Zhen-Long Yao; De-Li Wu; Xia Liu; Lu-Ming Ma

doi:10.1016/j.jhazmat.2023.131756

Pilot-scale study on an advanced Fe-Cu process for refractory wastewater pretreatment

J Hazard Mater. 2023 Sep 5:457:131756. doi: 10.1016/j.jhazmat.2023.131756. Epub 2023 Jun 2.

Authors

Jin-Hong Fan¹, Zhen-Long Yao², De-Li Wu³, Xia Liu², Lu-Ming Ma³

Affiliations

¹ State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science & Engineering, Tongji University, 200092 Shanghai, China; Key Laboratory of Urban Water Supply, Water Saving and Water Environment Governance in the Yangtze River Delta of Ministry of Water Resources, Tongji University, Shanghai 200092, China. Electronic address: jinhongfan@tongji.edu.cn.
² State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science & Engineering, Tongji University, 200092 Shanghai, China.
³ State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science & Engineering, Tongji University, 200092 Shanghai, China; Key Laboratory of Urban Water Supply, Water Saving and Water Environment Governance in the Yangtze River Delta of Ministry of Water Resources, Tongji University, Shanghai 200092, China.

PMID: 37270966
DOI: 10.1016/j.jhazmat.2023.131756

Abstract

The extreme pH, high color, and poor biodegradability of refractory wastewater have severe impacts on its biological treatment. To address this issue, an advanced Fe-Cu process with redox reaction and spontaneous coagulation was investigated and applied for pilot-scale (wastewater flow rate of 2000 m³·day^-1) pretreatment of separately discharged acidic chemicals and alkaline dyeing wastewater. The advanced Fe-Cu process had five functions: (1) increasing the pH of chemical wastewater to 5.0 and above, with an influent pH of approximately 2.0; (2) transforming refractory organics of chemical wastewater with 10.0% chemical oxygen demand (COD) and 30.8% color removal, thereby enhancing the ratio of biological oxygen demand after five days (BOD₅) to COD (B/C) from 0.21 to 0.38; (3) neutralizing the pH of the pretreated chemical wastewater for coagulation application with alkaline dyeing wastewater to avoid adding alkaline chemical; (4) achieving average nascent Fe(II) concentrations of 925.6 mg∙L^-1 using Fe-Cu internal electrolysis for mixed wastewater coagulation, resulting in an average of 70.3% color removal and 49.5% COD removal; (5) providing more efficient COD removal and B/C enhancement than FeSO₄∙7 H₂O coagulation while avoiding secondary pollution. The green process offers an effective, easy-implemented solution for the pretreatment of separately discharged acidic and alkaline refractory wastewater.

Keywords: Biodegradability improvement; Coagulation; Fe-Cu bimetal; Nascent Fe(II); pH adjustment.