Evaluation of a Membrane Process for Water Reuse

A membrane bioreactor and reverse osmosis (MBR-RO) system was developed to assess potential reuse applications of municipal wastewater. The objective of the study was to examine the water quality throughout the system with a focus on waterborne pathogens, and disinfection by-products (DBPs). This study has shown that high quality reuse water can be produced from municipal wastewater through the use of an MBR-RO system followed by disinfection. The disinfected reuse water meets California Title 22 strictest water reuse regulations for non-potable applications and US EPA drinking water limits for trihalomethanes (80 μg/L), haloacetic acids (60 μg/L), chlorite (1.0 mg/L), total coliform (not detectable) and viruses (not detectable). However, THM formation (182 to 689 μg/L) due to chlorine cleaning of the MBR's ultrafiltration (UF) membrane and incomplete removal by subsequent RO treatment resulted in reuse water THM levels (53.6 ± 23.1 μg/L) high enough to present a potential concern in drinking water applications.