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Innovative Constructed Wetlands for Removing Endocrine Disrupting Compounds from Reclaimed Wastewater

Project ID: 104
Principal Investigator: Michelle Chapman
Research Topic: Water Quality
Priority Area Assignments: 2012 (Advanced Water Treatment)
Funded Fiscal Years: 2012
Keywords: endocrine disrupting compounds, emerging contaminants, treatment wetlands, reclaimed water, wastewater, indirect potable reuse, water recycling and reuse

Research Question

What is the performance efficiency of constructed wetlands in removing organic wastewater compounds (OWC) and endocrine disrupting compounds (EDC) from municipal wastewater treatment plant effluent?

Presently in many parts of the arid western U.S., publically owned treatment works rely on direct or indirect reuse of reclaimed wastewater to meet increasing water demands. Treatment wetlands have been widely used to polish effluent from municipal, industrial, and agricultural wastewater treatment facilities by a complex interaction of physical, chemical, and biological processes that reduce concentrations of suspended solids, nutrients, dissolved organic carbon, volatile organic compounds, biochemical oxygen demand, and coliform bacteria [Sartoris et al. 2000; Barber et al. 2001; Keefe et al. 2004; Kadlec 2009]. Proper design is important, however, to ensure that essential components are functioning properly for the natural processes to occur at their optimum (Mitsch and Gosselink 2000).

Recently there has been worldwide concern over the fate of water borne consumer product chemicals such as pharmaceuticals, hormones, and other EDCs and their potential effects on aquatic ecosystems and human health. These compounds are ubiquitous in wastewater treatment plant effluents and, at combined concentrations, they have the potential to impact the reproductive health of fish and interfere with ecosystem function (NRC 1999; USEPA 2005; Vajda et al. 2008; Schoenfuss et al. 2008). While wetlands perform many of the processes known to break down or attenuate EDCs, effective removal has not been verified or optimized at the demonstration scale, and numerous critical data gaps remain with regard to incorporating wetlands into the public supply system. The research being proposed as part of this study will provide an opportunity to obtain unique insight into these issues, all of which are critical to ensure public health and safety as well as healthy ecosystems downstream.

Need and Benefit

The concept of indirect potable reuse is defined as the process of using reclaimed water for potable purposes by discharging wastewater to a water supply source, such as a surface water or ground water, and then using this supply source to dilute and/or treat the reclaimed water through natural processes. The mixed reclaimed/natural water may then receive additional treatment before entering the drinking water distribution system. Indirect potable reuse is showing great potential as a significant water supply strategy across the United States. Not only is it generally less expensive than alternative supplies, it tends to garner a lot of support from environmental advocates because associated wetlands can provide valuable habitat for fish and wildlife species, particularly migratory birds. However, critical knowledge gaps remain, particularly as it relates to identifying wetland characteristics that potentially affect treatment effectiveness for contaminants relevant for indirect potable reuse (i.e., hydraulic retention time, short-circuiting, selective planting strategies, etc).

According to the Texas State Water Plan, approximately 1.6 million acre-feet per year (15 percent) of Texas 2060 water supply needs will need to be provided through either the direct or indirect reuse of wastewater. To advance reuse in Texas, the Texas Water Development Board (TWDB) completed a research agenda in February 2011 that identified research on the performance of constructed treatment wetlands in improving reclaimed water quality as the second highest research priority of the State. Additionally, Orange County Water District (OCWD) has also recently supported proactive studies to assess natural attenuation processes in river and wetland systems. Because of this, it is clear that a better understanding of the operative transformation mechanisms within natural systems is important to develop more effective resource management tools and programs.

EDCs have uncertain impacts on endangered species and human health. Some impacts on the Santa Ana sucker have been identified. Regulators are in the process of analyzing these EDCs. Wetlands can be cost-effective strategies to mitigate EDCs; however, quantification of EDC reductions through wetland treatment has not occurred. This S&T project would provide the data necessary to validate constructed wetlands as low-energy treatment units for EDCs and could be widely used by our water district partners in complying with future EDC regulations. Toward that goal, we are proposing this scoping investigation to identify potential partners and an appropriate location to construct a relatively inexpensive, natural system at which we can test an innovative demonstration treatment wetland design to remove or degrade compounds of concern. We would like to solicit partners in Oklahoma, Texas, and southern California. Preliminary efforts show that North Texas Municipal Water District (TX), Tarrant County Water District (TX), City of Harlingen (TX), Central Oklahoma Master Conservancy District (OK), and Orange County Water District (CA) are all promising partners. We will seek out the community/partner showing the highest interest in pursuing this question and in genuinely helping us look for answers to develop a more useful tool in degrading EDCs and other emerging contaminants.

Contributing Partners

Oklahoma-Texas Area Office, Great Plains Region
Southern California Area Office, Lower Colorado Region
U.S. Geological Survey, Department of the Interior

Research Products

For FY12, create partnerships with interested entities and identify the location where the demonstration treatment wetland will be built. Using existing water quality as the focus on what to improve, a conceptual wetland design will be created with construction cost estimates and monitoring plans with the goal to remove compounds known to cause endocrine disruption in freshwater biota. For FY13 and beyond, the demonstration wetland will be built, monitored, and evaluated for its effectiveness in removing emerging contaminants. At the end of the study, a final technical memorandum will be prepared to submit to the S&T coordinators and partners. In addition to technical reports, a public outreach plan will be developed to disseminate the information learned. Our ultimate goal is to develop an effective treatment wetland design for removing emerging contaminants that could be used anywhere in the 17 western states.

This information was last updated on March 31, 2015
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