Recent Advancements in the Treatment of Municipal Wastewater Reverse Osmosis Concentrate-An Overview

Greater use of reverse osmosis (RO)-based processes in municipal wastewater reclamation presents the water industry with a major challenge regarding the sustainable management of the resultant RO concentrate (ROC) generated. This has promoted interest in investigating different approaches for the cost-effective treatment of ROC to reduce the risks associated with its disposal or reuse. This review highlights and discusses research on the treatment of ROC generated mainly from domestic wastewater. Methods employed for the treatment of municipal ROC are predominantly physicochemical processes, although biological processes with varying degrees of success in terms of the removal of organic content have also been reported. Relatively little attention has been paid to the quantification and removal of micropollutants. Due to the recalcitrant nature of some of the organics in ROC, advanced oxidation processes (AOPs) have been demonstrated to be the most effective for breaking down various pollutants and improving the biodegradability of the ROC. UV/H2O2, electrochemical oxidation, and ozonation are among the most studied AOPs for the treatment of ROC, and some have investigated posttreatment changes such as effect on molecular weight distribution and biodegradability improvement. Although these treatments appear to be promising, high energy consumption and the formation of harmful by-products during oxidative treatments are challenges that are yet to be fully addressed. Most studies have been conducted at laboratory scale and therefore large-scale investigation should be carried out to validate the effectiveness of these technologies.