Removal of contaminants of emerging concern is a top priority for the potable reuse of wastewater. To remove microbial and chemical contaminants, the full advanced treatment train, consisting of secondary treatment, microfiltration, reverse osmosis, and advanced oxidation processes is typically employed. For decentralized applications, where a low treatment plant footprint is desirable, forward osmosis-reverse osmosis (FO-RO) units could treat wastewater to high quality water in one treatment train unit. However, the removal of emerging contaminants present in wastewater, and minimizing the formation of disinfection byproducts, which are emerging contaminants that form during FO-RO effluent disinfection, are key challenges that FO-RO systems would need to overcome prior to their adoption for potable reuse.  This study evaluated a pilot scale FO-RO system intended for building scale non-potable reuse and its compliance with current Title 22 regulations over the course of six months. The applicability of the system to direct potable reuse and its ability to remove 19 contaminants of emerging concern, including pharmaceuticals and pesticides, present and spiked into wastewater, was evaluated. This study further evaluated the disinfection methods, including chlorination and chloramination, of the final effluent that would minimize the formation of 43 disinfection byproducts. We found that FO-RO treatment of wastewater complies with Title 22 regulations for non-potable reuse. We further found that FO-RO can successfully reduce the concentration of emerging contaminants in wastewater by more than &gt;99%. The disinfection by-product formation potential in the FO-RO effluents was low, with the effluents meeting the regulated trihalomethane and haloacetic acid regulations regardless of the disinfection method used. The FO-RO system further lowered the concentration of disinfection by product precursors present in the wastewater by more than 90%. While additional research is needed, the results of our study suggest that FO-RO has the potential to be used in decentralized potable wastewater reuse applications.

Evaluation of contaminant of emerging concern removal in wastewater by a hybrid forward osmosis-reverse osmosis system

2019 Fall National Meeting

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