Investigating techno-economic feasibility of biologically pretreated textile wastewater treatment by electrochemical oxidation process towards zero sludge concept

Abstract

Reverse osmosis (RO) membrane process is extensively employed in the hybrid zero liquid discharge (ZLD) based textile wastewater treatment plants to recover water for reuse in the dyeing processes. RO membrane fouling has been the major challenge due to the existence of organic foulants in the RO feed stream as it often affects the efficiency of the RO system. To fix this issue, an electrochemical oxidation (EO) technique was attempted to remove COD and colour from the biologically pre-treated textile wastewater as an advanced oxidation process. This study was performed using a small reactor setup with titanium (Ti) and stainless steel (SS 304) as an anode and cathode respectively. Reduction in COD and colour was obtained as 64% and 90% respectively at an electrolysis time of 3 min. The specific energy (Esp) consumption was estimated to be 19.16 kW h/ kg COD and 3.06 kW h/ m3 of influent. Cost-benefit analysis with factors like capital expenditure (Capex), operating expenditure (Opex), savings and pay-back period was carried out. The gross and net unit treatment costs of EO were 0.56$/m3 and 0.20$/m3 of influent respectively with the pay-back period of 1.90 years. Similarly, the gross and net treatment costs of EO on processing cost of dyed fabric were estimated to be 0.028$/kg and 0.011$/kg respectively. Cost analysis showed a considerable savings in costs associated with wastewater treatment and dyed fabric production, while zeroing of solid waste was achieved by adopting the EO process.