Safety
There some basic standards in place that define what level of treatment of wastewater effluents is required in order to provide sufficient safety to the public and for the environment when these wastewaters are reused.
- WHO (World Health Organization). In 2006, WHO published a third edition of its Guidelines for the Safe Use of Wastewater, Excreta and Greywater in Agriculture and Aquaculture. In four volumes, these Guidelines propose a flexible approach of risk assessment and risk management linked to health-based targets that can be established at a level that is realistic under local conditions. The approach is to be backed-up by strict monitoring measures.”
- Federal guidelines: EPA Guidelines for Water Reuse (2004)
- State regulations: e.g., Hawaii (HAR 11-62); Colorado; California; Massachusetts (2009); and Texas.
- guidelines issued by Canada’s National Water Research Institute;
- standards and guidelines of professional standards and research organizations.
A number of studies and reviews have been conducted on the safety of agricultural and other re-use of treated wastewaters. Among these studies are:
- the 5 year Monterey, CA study, which concluded, “that use of tertiary treated wastewater for food crop irrigation is safe and acceptable.”
- a St. Petersburg, FL study, which concluded “that there is no evidence of enteric diseases in urban regions housing areas irrigated with treated reclaimed wastewater” and that “there is no evidence of significant risk of viral or microbial diseases as a result of exposure to effluent aerosols from spray irrigation with [treated] reclaimed water.”
Thus, one group of reviewers of the Florida and California wastewater agricultural irrigation reuse programs and studies concluded, ” Use of recycled water for irrigation of food crops under regulatory regimes of California and Florida is safe and protective of public health.” Another author, an Australian, reached a similar conclusion: “Extensive and rational epidemiological studies have led to a consensus view that the actual risk associated with irrigation with treated wastewater is much lower than previously estimated, and the early microbiological standards were unjustifiably restrictive for wastewater reuse.” And EPA Region 9 says, “State and Federal regulatory oversight has successfully provided a framework to ensure the safety of the many water recycling projects that have been developed in the United States.” See also Vigneswaran and Sundaravadivel, “Wastewater Recycle, Reuse, and Reclamation, “ states, “Extensive and rational epidemiological studies have led to a consensus view that the actual risk associated with irrigation with treated wastewater is much lower than previously estimated, and the early microbiological standards were unjustifiably restrictive for wastewater reuse.”
In the past few years, however, concern has been expressed voiced about a range of newly identified threats: pharmaceuticals excreted or discharged into wastewaters, endocrine disrupting chemicals, resistant bacteria/viruses (RBVs), ARGs (antibiotic resistant genes), and post-treatment pathogen survival or growth ( inadequately sustained effectiveness of treatment) in treated wastewaters. References to these articles are provided below. As a result, there have been calls for additional treatment methods to be developed and/or applied and for more stringent standards to be developed or applied.
Several studies have demonstrated technology that can effectively treat pharmaceutical remnants in wastewater. See, for example:
- the 2007 study of pharmaceuticals in hospital wastewater that found that use of “sedimentation . . . ultraviolet light, hydrogen peroxide and ozone” to treat these wastes . . . deactivated all active components.”
- the 1998 National Academy of Sciences report that concluded, ” Current potable reuse projects and studies have demonstrated the capability to produce reclaimed water of excellent measurable quality and to ensure system reliability. In communities using reclaimed water where analytical testing, toxicological testing, and epidemiological studies have been conducted, significant health risks have not been identified.”
- the San Diego treatment effectiveness studies that showed “removal efficiency” of up to “99.99999999 percent” of the seeded viruses so that none were found in the final effluent when reverse osmosis technology was used.
There are processes in place to update existing standards in light of new information about risks and technology. For example:
“June 12, 2009 – Standards Institution of Israel has submitted proposal to ISO for standard on treated wastewater reuse implementations. As U.S. member body to ISO, ANSI [the American National Standards Institute] invites interested stakeholders to submit comments by July 24. Proposed standard will cover requirements and processes involved in healthy, environmentally viable, and sustainable reuse of treated wastewater in agriculture, landscape, and industry. It will also offer guidelines for design, construction, operation, and maintenance of such systems.”
“Advanced wastewater treatment plants in Lake Tahoe, California and Windhoek, South Africa have been achieving drinking water quality since 1968.”
In Denver, CO, these concerns are managed through a combination of Ecoli and turbidity standards and the treatment techniques necessary to ensure compliance with these standards. See slides 10-17 in the Denver presentation.