Electrocoagulation pre-treatment to simultaneously remove dissolved and colloidal substances and Ca2+ in old corrugated container wastewater

• Published in: Chemosphere (Oxford) 2021-04, Vol.268 (C), p.128851, Article 128851
• Main Authors: Liu, Hui, Wu, Yueru, Li, Mingfu, Ma, Haitong, Li, Meiling, Zhu, Kaili, Jian zhang, Chen, Guoning, Wang, Zhiwei, Wang, Shuangfei
• Format: Article
• Language: English
• Subjects: Calcium ions; Chemical oxygen demand: COD; DCS; Dissolved and colloidal substances: DCS; ECP; Electrocoagulation pre-treatment: ECP; Electrocoagulation: EC; Floc; Micro stickies; OCC wastewater; Old corrugated container: OCC
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2020.128851

An effective electrocoagulation pre-treatment (ECP) method was proposed to simultaneously solve the problems of the micro stickies deposition and high Ca2+ content in old corrugated container (OCC) papermaking wastewater during the recycling process. The optimal ECP condition was investigated. The results indicated that the effect of an Al electrode on wastewater treatment was superior to that of a Fe or Mg electrode. The optimal treatment conditions of the current density, electrode distance and reaction time were 115 A m−2, 5 cm and 60 min, respectively. After the ECP, the chemical oxygen demand (COD) and Ca2+ removal rates were 75.33% and 64.53%, respectively, and the turbidity and dissolved and colloidal substance (DCS) content decreased by 97.1% and 43.68%, respectively. The particle size of flocs in the liquid increased from 1.675 μm to 31.97 μm, and the floc content was 0.78 g L−1 after ECP. The anode material and energy consumption were 0.1846 kg m−3 and 4.56 kWh m−3, respectively, and the cost of treatment was estimated to be 1.11 $ m−3. The results demonstrate that ECP can effectively remove the micro stickies, COD, and Ca2+ in the OCC wastewater, which is conducive to reducing the cost of wastewater treatment and conform to the requirements of sustainable development. [Display omitted] ●Optimum treatment was achieved with Al as the anode.●DCS and Ca2+ were simultaneously removed by Electrocoagulation pre-treatment (ECP).●DCS content removal was proportional to turbidity and Ca2+.●Turbidity and COD removal rates by ECP were 98.1% and 75.33%.●ECP demonstrated practical value for OCC wastewater.