The need for more efficient use of water from all of its sources has become axiomatic, and it is a critical issue in many water-short areas. Wastewater is a valuable commodity that can be processed, and its components can be completely reused for a variety of purposes including as a source of highly treated water for human consumption (Cotruvo, 2012).

Indirect potable reuse (IPR) implies that reclaimed water is returned to the environment before being sourced for water supply. Direct potable reuse (DPR) involves the delivery of highly treated reclaimed water (with or without retention in an engineered storage buffer) to a drinking water plant or distribution system. Unplanned de facto IPR has been common practice for many years, as in discharge of treated or untreated wastewater to a water course upstream from a drinking water plant intake. Planned IPR and DPR are quickly becoming viable and possibly necessary options for many areas where water availability is turning into a critical need. Numerous states and some countries are engaged in projects producing drinking water via DPR or IPR technologies (Crook et al, 2005). The rapid advances in process technologies and monitoring techniques have made these reuse technologies plausible and safe options, and have demonstrated the capability to produce water of higher quality than many typical drinking water supplies. There is, however, a gap in the availability of guidance and benchmarks that can be used by planners, designers, operators, and regulatory decision-makers to help them make wise choices and implement the appropriate technologies to ensure safe, economical, and sustainable reclaimed water systems.

In the United States, the Clean Water Act and the Safe Drinking Water Act regulate sourcewaters and drinking waters. Thousands of water suppliers provide drinking water by de facto IPR from sourcewaters with upstream wastewater discharges. They are successfully managed in the United States by reasonably comprehensive drinking water standards that include filtration and disinfection treatment requirements and Maximum Contaminant Levels for almost 100 organic and inorganic chemicals, microbials, and radionuclides, and more than 500 drinking water health advisories.

However, advanced treatment systems in planned IPR or DPR projects receive greater scrutiny than de facto
reuse, with DPR receiving ultimate scrutiny. Drinking water of exceptional quality produced through planned
IPR is well documented. There is a developing consensus among experts that DPR is a feasible approach to
producing safe drinking water, and it may well produce higher-quality water and be less costly than IPR project options (NRC, 2012; USEPA, 2012).
GUIDANCE DEVELOPMENT
The WateReuse Association’s National Regulatory Committee has proposed that the time is ideal for providing water-reuse guidance principles that would help regulators, practitioners, and public health professionals achieve consensus on the questions regarding public health, safety, and reliability.

The authors believe that detailed, comprehensive criteria are needed for decision-makers to ensure confidence in the quality and safety of reclaimed water for potable applications. National water reuse regulations are not being developed. State regulators often must operatewith some level of isolation and make major decisions without direct guidance from national regulatory authorities. This could lead to decisions that are not representative of the state of the art or that have excessive redundancies that can impede the implementation of essential projects and cause unnecessarily high costs and delays. On the other hand, some choices might not require adequate multibarrier treatment, redundancies, process monitoring, operator training, or other elements necessary to ensure protection of public health.

The WateReuse Association has undertaken a process for developing consensus guidelines for IPR and DPR. It defined DPR as a practice that does not include an environmental buffer in the treatment train, and it defined IPR as a practice that includes an environmental buffer (such as a reservoir, aquifer, wetlands, or river) in the treatment train. Several large-scale, planned IPR projects have been in operation for many years, typically providing treated water for soil aquifer treatment and aquifer recharge, or using wetlands to enhance the quality of treated effluent before use as a drinking water supply. Planned potable reuse projects receive greater scrutiny because of concerns about the variability and not completely controlled composition of wastewater sources. Of particular concern are sourcewater pathogen concentrations, and trace chemicals are of possible concern, including those in pharmaceuticals and personal care products, endocrine-active chemicals, industrial chemicals, and others, depending on the source and the level of wastewater treatment being provided.

The public and some regulators are naturally skeptical about potable reuse when they do not have complete
information on the safety of the processes and resulting water quality. This gives rise to debates among technical stakeholders that add to confusion and misgivings. The National Research Council report on Water Reuse (NRC, 2012), USEPA 2012 Guidelines for Water Reuse (USEPA, 2012), Water Reuse: A Path Forward (Tchobanoglous et al, 2011), and other sources provide background for developing a document representing a consensus of independent and knowledgeable health and technology professionals who would provide a framework of principles and recommendations regarding IPR and DPR to ensure the health and safety of consumers. Guidelines are available for nonpotable recycling in food and beverage production
(ILSI, 2013).

SURVEY ON THE STATUS OF THE REGULATORY FRAMEWORK FOR POTABLE REUSE
An ad hoc group of experienced professionals was assembled by the WateReuse Association to examine
the state of the regulatory landscape and provide recommendations for appropriate next steps. (Members of
the ad hoc Reuse Guidelines State Activities Committee are Katherine Bell (vice-chair), Bob Bastian, James
Bolton, Guy Carpenter, Joseph Cotruvo (chair), James Crook, Mark Farrell, Brian Good, Ellen MacDonald,
Wade Miller, Tom Richardson, and David Smith.)

A survey was conducted with the Association of State Drinking Water Administrators to obtain feedback on
the status of state policies, activities, and plans. The principal task was to obtain information on current regulations, guidelines, and interests from state regulators on state regulatory structures, status of activities involving surface and groundwater augmentation, IPR, and DPR.
FINDINGS
The 30 responses indicate that DPR and IPR are not current issues in most states, but several are working
toward guidelines or standards. On the other hand, more than half of the respondents indicated that there
were groups promoting potable reuse in their state, including water utilities, environmental groups, community
groups, and municipal or state authorities, and engineering consultants, industry, and equipment suppliers.
There were also opposing groups identified as some state drinking water and public health agencies and individuals in the general public opposed to the high costs of reuse or who posed likely consumer concerns
associated with reuse.
Most respondents indicated that additional guidance would be beneficial. Their preferred format was federal
guidelines. Other possible formats were WateReuse Association consensus guidance, international guidelines such as the International Organization for Standardization and the World Health Organization, or independent certifications. Respondents were seeking authoritative technical and policy guidance regardless of the format.

The primary drivers for potable reuse included water quantity and quality, environmental concerns, and statutory requirements for sustainability and economic development, for reducing effluent discharges, and that
set reclaimed-water goals. Several respondents indicated that they consider IPR projects on a case-by-case basis, and several others would consider the practice if a project were proposed.

The lack of activity in some states may be because of either a sense that they have adequate drinking water
supplies and do not need to provide additional sources or that the issue is sufficiently controversial and unresolved, and that their involvement was premature. Nevertheless, most states acknowledge that de facto wastewater reuse from upstream discharges is occurring. They are apparently relying on the existing drinking water standards along with effluent discharge controls and permits to ensure drinking water safety. However, improved technologies and expectations of ever higher drinking water quality will likely continue to drive water suppliers to more rigorous treatment and probably lead to revised definitions of conventional treatment.

Among the procedural operational issues, those states that were developing frameworks to support  potablereuse strategies—e.g., California, Florida, Georgia, and Texas—indicated that piloting or other demonstration projects would be required. Virginia and Arizona indicated that strategies would be determined on a case-bycase basis. Appreciation is growing for the capabilities of technological strategies that have been successfully applied in several long-standing water reuse applications. Some of these are considered high tech (e.g., reverse osmosis or advanced oxidation), but more traditional technologies such as land application (including wetlands) and soil aquifer treatment are also successful components of multibarrier-reuse treatment trains. The authors suspect that piloting will almost always be necessary
before acceptance and implementation of a DPR or IPR reuse project. As the operational experience continues to expand, the extent and time requirements of piloting will likely focus on training and ensuring the
operational success under the project conditions rather than determining the acceptability of the technology.

Regarding obtaining external technical support for potable reuse projects, Arizona, California, Georgia, and
others indicated that some form of stakeholder or external advisory panel would be used for oversight and
guidance. The authors believe that in this introductory phase, the needs to address public questions and to
assist regulators will make substantial expert and stakeholder participation an important element of most, if
not all, proposed IPR and DPR projects.

CONCLUSIONS
IPR and DPR are not major issues in many states, but they are significant under circumstances in which water
availability is a major concern. Water availability concerns will likely increase. In addition, the public is developing a sense of the need to implement concepts that are more sustainable, more efficient, and less environmentally damaging, and wastewater recycling is an opportunity to accomplish those ends. Lack of public and regulator familiarity with reuse is also an impediment to more widespread wastewater reuse. A gap exists as a result of the lack of authoritative comprehensive guidelines, which impedes progress and delays decision-making.

Finally, educating decision-makers and the public about the safety and high quality of product water and
the benefits of multiple usage of wastewater is essential.  This can be accomplished when the need for reuse
is established and its costs and benefits are understood, and agreement is reached on the appropriate water
quality goals so that de novo assessments are not required by regulators and controversies about current
unknowns are resolved.

In the near term, the likelihood of specific federal regulations or guidelines is small. The WateReuse
Association and the National Water Research Institute are initiating a joint effort to develop reuse guidelines
to provide the support that decision-makers need in order to move forward.

原文链接：http://www.awwa.org/publications/journal-awwa/abstract/articleid/43502027.aspx

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