Evaluation of methods for reverse osmosis membrane integrity monitoring for wastewater reuse

Abstract

Wastewater reclamation with advanced membrane technology holds great potential to supplement the diminishing drinking water supply for human consumption. High-pressure reverse osmosis (RO) membrane processes offer a high level of pathogen removal capacity. However, the lack of recognized membrane integrity monitoring methods has restricted the pathogen removal credits allocation to the processes. This research investigated the feasibility of using flow cytometry (FCM), dynamic light scattering (DLS) analyzer and traditional water quality analyzers for RO membrane integrity monitoring. BD Accuri™ C6 flow cytometer demonstrated good sensitivity and reproducibility for quantifying virus reduction rate along the treatment processes, which provide direct evidence for RO membrane integrity monitoring. DLS (Nanotrac Ultra) showed promise to be used as a qualitative membrane integrity monitoring tool by characterizing particle size distributions in water. Traditional water quality analyzers were tested online in a pilot RO system with intentional introduced integrity breaches. Total organic carbon (TOC) measurements showed the best sensitivity to reflect different levels of integrity breaches. Feasibility analysis based on the instrument sensitivity, capital, maintenance and operating costs shows that an integrated system including more than one monitoring tools would be more reliable and economical for high-pressure membrane integrity monitoring.