Treatment of dye laden wastewater through electrocoagulation :

Abstract

Wastewater discharge from textile sector has raised certain concerns, resulting in an unavoidable trade-off between industrial growth and environmental degradation. According to statistics, textile sector generates 200-350 m3 of wastewater per ton of finished product which results in higher COD ranging from 300-10,000 mg/L. Advanced Oxidation Processes (AOPs) are effective treatment methods for degradation of the recalcitrant wastewater. These processes involve the formation of hydroxyl radical which is highly oxidative and non-selective for most of the organic pollutants. However, high chemical consumption simultaneous with high energy requirements limits their industrial applications. Thus, in order to trade-off chemical consumption and energy equipment, electrocoagulation is identified a viable approach. In electrocoagulation, difference in electric potentials is utilized to generate coagulants which can remove color and other recalcitrant organic contaminants. It not only renders the consumption of chemicals but also reduces the sludge formation and thus reduces the operating cost of the process. Therefore, keeping these aspects in view, this study aims at treating dye laden wastewater through electrocoagulation using Iron (Fe) as electrode material. Congo red, an azo dye, was used as probe pollutant and central composite design was used to design and optimize the process conditions. The key parameters include initial dye concentration, pH and electrode distance were used to study their effects on decolorization and COD removal. According to experimental results, pH and electrode spacing were most significant factors with maximum COD and degradation efficiency of 90% and 97% respectively. Furthermore, the results showed that acidic conditions and inter electrode spacing have significant contribution towards overall performance of electrocoagulation and further process optimization may enhance the viability of this process due to the possibility of zero water discharge and reusability of dye in the textile sector.