Fouling behavior and cleaning strategies of ceramic ultrafiltration membranes for the treatment and reuse of laundry wastewater

One of the most promising strategies for maintaining stable water sources for on-site wastewater reuse is greywater reclamation, particularly laundry wastewater reclamation. This study proposes an efficient strategy for the pre-treatment of laundry wastewater, which reduces membrane fouling and improves flux recovery after membrane cleaning. The fouling behavior, organic retention, and flux recovery rates of ceramic ultrafiltration (UF) membranes were comprehensively investigated using synthetic laundry wastewater. Under identical applied pressure and temperature conditions, a fouling resistance that corresponded to the water permeate flux and normalized flux was explored. Total organic carbon (TOC) retention was also tested to investigate the feasibility of using ceramic UF membranes as an effective pre-treatment for laundry wastewater reclamation. Furthermore, four different cleaning strategies for the fouled ceramic membranes were systematically compared, including deionized (DI) water, alkaline, acidic, and combined alkaline and acidic chemical agents to provide an in-depth understanding of the potential recovery rates of the membranes relative to the initial state. The filtration and treatment performance of real laundry wastewater samples collected from a university student dormitory was compared with synthetic laundry wastewater. This work provided valuable information on fouling behavior and cleaning strategies that could advance ceramic UF membrane pre-treatment technology for sustainable laundry wastewater reuse. Despite the challenges associated with the organic fouling and the potential of incomplete flux recovery in engineered systems, our findings provide insights into fouling mechanisms and cleaning strategies that could enable the optimization of engineered wastewater reuse systems.