Application of iron tailings in the coagulation of landfill leachate by bipolar membrane electrodialysis

• Published in: Journal of cleaner production Vol. 448; p. 141679
• Main Authors: Jin, Yanchao, Wang, Guodong, Li, Zheng, Lin, Chun-Yan, Li, Li-Ping, Chen, Xiao, Ding, Rui, Liu, Jianxi, Chen, Riyao
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 05.04.2024
• Subjects: Bipolar membrane; Coagulation; Iron tailings; Landfill leachate; Bipolar membrane; Iron tailings; Landfill leachate; Coagulation
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2024.141679

Landfill leachate contains large amounts of non-biodegradable organic matter. The recalcitrant substances become more concentrated following the treatment using a combination of biological methods and nanofiltration. In this study, the nanofiltration concentrated landfill leachate (NCLL) was subjected to coagulation treatment using the bipolar membrane electrodialysis (BMED) process with iron tailings. The H+ required for metal leaching and OH− for coagulation are supplemented by water dissociation. The pH value of the NCLL played an important role for coagulation and the suitable pH value was 4. As the resource of the coagulant, a certain amount of iron tailing is needed. The energy consumption (EC) for chemical oxygen demand (COD) removal was about 0.70 kW h/g COD with 10 g tailing. Pretreating the tailing with 0.2 mol/L HNO3 could enhance the coagulation process, resulting in a COD removal ratio of 67.3% within 4 h. Increasing the current density improved the COD removal rate, but consumed more electricity. Employing more treatment units is a viable approach to reduce EC. It decreased to 0.045 kW h/g COD when two treatment units connected together. Humic like acids and fulvic like acids present in the NCLL have been effectively removed. This study provides a way of ‘treating the wastes with wastes’ for NCLL treatment. [Display omitted] •BMED systems were employed to treat landfill leachate using iron tailings.•H+ for metal leaching and OH− for coagulation are provided by water splitting.•The COD removal rate of the landfill leachate reach to 67.3 % within 4 h.•Connecting more treatment units could reduce the energy consumption.•The EC was about 0.045 kW h/g when two treatment units connected in series.