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Evaluation and optimization of electrocoagulation for treating Kraft paper mill wastewater
Journal article   Peer reviewed

Evaluation and optimization of electrocoagulation for treating Kraft paper mill wastewater

Dipendra Wagle, Che-Jen Lin, Tabish Nawaz and Heather J. Shipley
Journal of environmental chemical engineering, Vol.8(1), 103595
02/2020
DOI: https://doi.org/10.1016/j.jece.2019.103595
Web of Science ID: WOS:000515128500045

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Abstract

Biodegradability Electrocoagulation Response surface methodology Biodegradation Chemical Engineering Optimization
The performance of electrocoagulation (EC) using iron as sacrificial electrode was investigated at low current densities (0.6–1.9 mA/cm2) for treating a waste stream from a Kraft paper mill. A multi-level factorial design of experiments and response surface methodology (RSM) were applied to quantify the effects of current density and reaction time on the removal efficiency of color, COD, BOD5, tannin/lignin as well as on the enhancement of biodegradability index (BI). Increasing current density or reaction time significantly improve the treatment performance. An antagonistic effect of the two studied factors was identified, indicating that simultaneously increasing current density and reaction time does not yield added improvement in treatment performance. An RSM was developed to predict the optimum current density and reaction time within the experimental data range of this study. It was found that an optimized treatment combination exists at relatively low current density and reaction time. The optimum value for maximum pollutants removal was ∼1.5 mA/cm2 and ∼25 min. Under the optimum condition, the removals of tannin/lignin and color were >70 % and >95 %, and BI was increased to 0.41 BOD5/COD. Current density is the dominant factor for energy consumption and operating cost compared to reaction time and electrode consumption. This study demonstrated that EC can be operated at low current density to remove the bio-refractory organics effectively and increase the biodegradability index to the level suitable to biological treatment at low operating costs.

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