Treating reverse osmosis brine of petrochemical wastewater using preparative vertical-flow electrophoresis (PVFE) with multi-objective optimization by response surface method

Abstract Recovering salts from reverse osmosis (RO) brine has long been a major concern in the field of industrial wastewater treatment. To address this issue, this study implemented a preparative vertical-flow electrophoresis (PVFE) system to treat the RO brine from petrochemical wastewater. Additionally, the response surface method was utilized to optimize the operational parameters related to acid-base production and energy consumption. The results demonstrated that the PVFE could efficiently recover acids and bases from the brine at electric field strengths ranging from 89.37 V/m to 185.08 V/m. The electric field strength was found more influential than the flow rate in terms of both acid/base concentration and energy consumption during the treatment. By applying the central composite design methodology, the optimized operating parameters led to a significant reduction in energy consumption for acid and base production, with a decrease of 254.81% and 168.67% respectively, compared to the original operating parameters. However, it is worth noting that the base and acid concentrations were also reduced by 71.91% and 104.97% respectively. As a result, there was a trade-off between the recovered acid-base concentration and energy consumption. These findings provide a directed and practical solution for recycling waste salt resources from RO brine.