Reduction of COD and removal of Zn²⁺ from rayon industry wastewater by combined electro-Fenton treatment and chemical precipitation

In this study a stepwise combination of electro-Fenton process and chemical precipitation was used to treat rayon industry wastewater and reduce its chemical oxygen demand (COD) and Zn²⁺. Results obtained with industrial wastewater having a COD of 2400mg/L and 32mg/L Zn²⁺ revealed that approximately...

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Bibliographic Details
Published in:Desalination 2011-01, Vol.266 (1-3), p.213-217
Main Authors: Ghosh, Prabir, Samanta, Amar Nath, Ray, Subhabrata
Format: Article
Language:English
Subjects:
Applied sciences
Chemical engineering
chemical oxygen demand
chemical precipitation
chemical treatment
Crack opening displacement
Crystallization, leaching, miscellaneous separations
Current density
desalination
electrodes
energy
Exact sciences and technology
General purification processes
graphene
industry
Lime
Pollution
Precipitation
Rayon
Reactors
Reduction
Waste water
wastewater
Wastewater treatment
Wastewaters
Water treatment and pollution
Zinc
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Summary:In this study a stepwise combination of electro-Fenton process and chemical precipitation was used to treat rayon industry wastewater and reduce its chemical oxygen demand (COD) and Zn²⁺. Results obtained with industrial wastewater having a COD of 2400mg/L and 32mg/L Zn²⁺ revealed that approximately 88% COD was reduced in 50min using the electro-Fenton method with an optimized H₂O₂ dose of 1530mg/L and a current density of 0.90A/dm² but this step does not have any appreciable effect on zinc removal. The most effective zinc removal (99–99.3%) was in the range of pH 9–10 using lime (CaO) precipitation. Electro-Fenton studies were with current density in the range of 0.45A/dm² to 1.80A/dm² and H₂O₂ dosage in the range of 765mg/L to 3825mg/L. Experiments were carried out in a batch reactor using two electrodes — iron anode and graphite cathode. COD reduction increased with cell current up to a limit and then deteriorated. Energy consumption of the electro-Fenton method was 1.7kWh/kg COD removed at the optimized conditions. A combined method of electro-Fenton followed by lime precipitation is therefore proposed as an effective method for treatment of rayon industry wastewater containing high COD and zinc.
ISSN:0011-9164
1873-4464
DOI:10.1016/j.desal.2010.08.029