Electrochemical decolorization of methyl red by RuO2-IrO2-TiO2 electrode and biodegradation with Pseudomonas stutzeri MN1 and Acinetobacter baumannii MN3: An integrated approach

Abstract

Textile effluent consists of enormous quantities of toxic dyes, which are being discharged into natural aqueous system and thus contaminate the water quality. Hence it is important to develop an eco-friendly and cost effective technology to treat the dyes contaminated wastewater. In this research, an integrated approach of electrochemical oxidation (EO) and biodegradation process (BP) was studied of methyl red (MR) dye. In EO, RuO2-IrO2-TiO2 is used as anode and titanium mesh electrode as cathode. This was followed by BP of the treated EO effluent. Various parameters viz., pH (5–10), sodium chloride concentrations (NaCl) (1–5 g L−1) and current density (10–30 mA cm2) were optimized. The results of the EO showed 99.96% of MR decolorization within 10 min at pH of 5, NaCl of 2 g L−1 and current density of 30 mA cm2. The EO treated MR was further treated by BP Pseudomonas stutzeri MN1, Acinetobacter baumannii MN3 and mixed consortia of MN1 and MN3. The out of three treatments, the results of mixed consortium BP showed 90% removal of COD at the end of 24 h. The phytotoxic evaluation using Vigna radiata seeds confirmed the toxicity of untreated MR solution, whereas, 100% germination was observed in treated (biodegraded) MR solution. Overall these results evidenced that MR dye was completely decolorized and mineralized by EO and BP within 10 min and 24 h respectively. Hence, this integrated approach can be used as an effective degradation method to treat dyes in the textile industry.