Comparative Assessment of Chemical Coagulation and Electrocoagulation for Industrial Wastewater Treatment

The selection of an appropriate coagulation technology for wastewater treatment remains a critical challenge for environmental engineers, balancing removal efficiency, operational cost, sludge management, and environmental footprint. This paper presents a comprehensive comparative assessment of chemical coagulation (CC) using alum (Al₂(SO₄)₃·۱۸H₂O) and ferric chloride (FeCl₃) versus electrocoagulation (EC) using aluminum and iron electrodes for the treatment of synthetic textile wastewater and real municipal wastewater. Bench-scale experiments were conducted under optimized conditions: CC at pH ۶.۵–۷.۵ with coagulant doses of ۲۰–۱۲۰ mg/L; EC at current densities of ۲–۱۰ mA/cm² with electrode spacing of ۱ cm and treatment time of ۵–۳۰ minutes. Results indicate that EC achieved superior removal efficiencies: turbidity (۹۸.۷% vs ۹۱.۲% for CC), chemical oxygen demand (COD) (۸۹.۴% vs ۷۶.۸%), and color (۹۶.۲% vs ۸۲.۵%). However, CC produced ۴۲% less sludge volume and had ۳۵% lower electrical energy consumption, though chemical costs were higher. Electrode passivation and energy consumption remain key challenges for EC scale-up. The paper provides a decision matrix for technology selection based on wastewater characteristics, treatment targets, and economic constraints. Sludge characterization using SEM-EDS and FTIR revealed distinct morphological and compositional differences, with EC sludge showing higher metal hydroxide content and better dewaterability. Life cycle assessment (LCA) indicates that EC has lower global warming potential when renewable energy is used. Recommendations for hybrid systems are proposed.

کلیدواژه ها:

Electrocoagulation ، chemical coagulation ، wastewater treatment ، sludge characterization ، textile wastewater ، aluminum electrodes ، ferric chloride ، techno-economic analysis