Improvement of water quality of remnant from chemical retting of coconut fibre through electrocoagulation and activated carbon treatment

Abstract

Remnant obtained from chemical retting of coconut fibre was found to have an exorbitant COD, BOD, TDS, sulphide content having blackish brown colour. Traditional (physico-chemical) treatment could not reduce its COD, TDS, colour substantially. Further, the traditional method was lengthy, consumed huge chemicals and time. Present paper reports a quicker, simpler, economic i.e., an industrially viable method to separate the chemicals and biomass by employing electrocoagulation (EC). The performance of EC was analyzed by keeping temperature, and pH of remnant constant, while varying current flow (100–2000 mA), time (15–90 min) and number of iron electrodes (2,4,6). Efficacy of EC was evaluated in terms of reduction in conductivity, pH, TDS, COD, TOC, colour and quantity of sludge generated from the wastewater. Six electrodes with 2000 mA current flow for 90 min were found to give noticeable reduction on COD (92.8%), TOC (56%), TDS (99%), and colour. To reduce pH, and TDS to an acceptable level, filtration with activated charcoal was attempted on recovered water from EC. Resultant water was also found to have acceptable LC50 value for safe disposal. Carbon content (53%) in the sludge was high, contained lignin and cellulose whiskers also, as revealed from the EDX and FTIR, SEM respectively. Cost of EC ($ 0.087 USD/L) was found to be much less as compared to traditional method ($ 0.384 USD/L).