Evaluation of an Innovative Constructed Wetland Designed to Remove Endocrine Disrupting Compounds from Reclaimed Wastewater
Publically owned treatment works in the arid western states are increasingly relying on direct or
indirect reuse of reclaimed wastewater to meet water demands. The use of treatment wetlands
to polish effluent from municipal, industrial, and agricultural wastewater treatment facilities by
reducing concentrations of suspended solids, nutrients, dissolved organic carbon, volatile
organic compounds, biochemical oxygen demand, and coliform bacteria through a complex
interaction of physical, chemical, and biological processes has been well documented. Proper
design is important however, to ensure that essential components are functioning properly for
the natural processes to occur at optimum levels.
Recently there has been worldwide concern over the fate and potential impacts on aquatic
ecosystems and human health of water borne consumer product chemicals, such as
pharmaceuticals, hormones, and other EDCs. EDCs 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. 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 regards to
incorporating wetland effluent 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 & safety and healthy ecosystems downstream.
References: Sartoris et al. 2000; Barber et al. 2001; Keefe et al. 2004; Kadlec 2009; Mitsch and
Gosselink 2000; NRC 1999; USEPA 2005; Vajda et al. 2008; Schoenfuss et al. 2008.
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 groundwater, 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 U.S. 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 TWDB completed a research
agenda in February 2011 which identified research on the performance of constructed treatment
wetlands in improving reclaimed water quality as the second highest research priority of the
Endocrine disrupting compounds often found in municipal wastewater 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 monitoring 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 utilized by
our water district partners in complying with future EDC regulations.
During the recent and continuing drought, the fact of water reuse has become more apparent.
People can see that no rain has fallen and the only input to the local reservoir is from the
wastewater treatment plant. During times of drought, natural wetland systems are all that
separates the wastewater effluent from someone's drinking water influent. A better
understanding of the capability of natural treatment systems may give us clearer insight into the
degree of treatment necessary for direct water reuse.
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