Pressure retarded osmosis coupled with activated sludge process for wastewater treatment: Performance and fouling behaviors

A novel hybrid technology integrating pressure retarded osmosis with activated sludge process (denoted as PRO-MBR) was proposed in this study for wastewater treatment. Here, performance and fouling behaviors of PRO-MBR were investigated. Excellent contaminants removal and power production were simultaneously achieved in the PRO-MBR. A significant drop of water flux in the PRO-MBR was mainly due to the severe fouling of the support layer in forward osmosis (FO) membrane including internal fouling and external fouling. Although the external fouling was identified to be the major type of fouling, the internal fouling dominated the overall decline of water flux. In addition, organic foulants and biofoulants were the dominant foulants for the external fouling while inorganic foulants were equal to organic foulants and biofoulants for the internal fouling. According to the variations of water flux in the PRO-MBR, the development of support layer fouling was divided into three stages.