The National Science Foundation (NSF) has awarded San Diego State University Graduate School of Public Health and College of Engineering a $300,000 grant to support research in Decentralized Waste Water Treatment Systems (DEWATS). The principal investigators are Drs. Nathan Dodder and Eunha Hoh of the Graduate School of Public Health and Dr. Natalie Mladenov of the department of civil, construction, and environmental engineering. The project aims to evaluate the ability of these small-scale systems to remove chemical contaminants.
The wastewater infrastructure in the U.S. and many developed countries is largely centralized, and may fail as systems reach the end of their design life. As an alternative to replacing failing sewer pipe, DEWATS can provide a level of treatment needed for non-potable water uses such as landscape irrigation, and, coupled to membrane or other advance treatment technologies, may ultimately be used for potable reuse. The optimization of treatment performance through contaminant monitoring during treatment will enable DEWATS to achieve competitive removals efficiencies and gain greater acceptability for potable and non-potable water reuse applications.
A simultaneous issue, however, is current targeted analytical tools for contaminant measurement may miss unexpected or unknown chemicals. A more comprehensive approach is needed for the evaluation of not only parent contaminants in wastewater treatment systems, but also their metabolites. Therefore, a novel non-targeted mass spectrometry method will be used to identify the potentially broad range of compounds. The contaminants and their potential byproducts generated during the treatment process pose an unclear risk to human health, and the mechanisms by which these chemicals are removed or transformed in DEWATS are key issues this project seeks to address.
The research project has three objectives. First, to evaluate the removal or transformation of chemicals by aerobic and anaerobic membrane treatment systems, compared to a conventional activated sludge treatment system. Aerobic and anaerobic membrane bioreactor technology (MBR and AnMBR, respectively) are two potential DEWATS technologies that require evaluation. Second, to evaluate how physical-chemical properties of the identified contaminants affect their removal and transformation in membrane reactor systems under aerobic and anaerobic conditions. Third, to evaluate additional contaminant removal and transformation due to photolysis in irradiated MBR and AnMBR permeate to simulate sunlight-exposed or photobioreactor conditions.
The non-targeted analytical approach applied to the parallel aerobic and anaerobic treatment system design will provide an unprecedented evaluation of the transformation processes of contaminants. The research will also investigate how photolysis, which is critical in pond or wetland treatment systems that tend to follow anaerobic treatment, contributes to contaminant removal and transformation. The impact of this work will be far reaching for the water reuse field because this comprehensive evaluation of contaminants in small-scale membrane treatment systems will inform the growing decentralized movement in the U.S. and abroad.
For outreach, the research team will develop a hands-on activity focused on water reuse for the “We are STEM” SDSU Enrichment Program.