Water Reuse Policies for Potable Use

Cecilia Tortajada, Choon Nam Ong, Cecilia Tortajada, Choon Nam Ong

• Verlag: Routledge
• Jahr: 2018
• ISBN:
  9781351794152
• Auflage: 1
• Thema: Politics & International Relations
• Thema: Environment & Energy Policy

As water demand has increased globally and resources have become more limited because of physical scarcity, over-exploitation and pollution, it has been necessary to develop more options for water supplies. These options include the production at large scale of high-quality reused water from municipal sources for potable uses. Their economic, social and environmental benefits have been many as they have addressed supply scarcity, efficient resource use and environmental and public health considerations.

This book includes discussions on potable water reuse history; emerging contaminants and public health; public-private partnerships in the water reuse sector; regulatory frameworks for reused water in the United States and Europe; experiences in Australia, China in general and Beijing in particular, Singapore and Windhoek; narratives and public acceptance and perceptions of alternative water sources.

The main constraints on implementation of water reuse projects in different parts of the world seem to have been lack of full public support due to perceived health hazards and environmental impacts. A main handicap has been that governments and water utilities have been slow to understand public concerns and perceptions. After several backlashes, public information, communication and awareness campaigns, broader participation and educational programmes have become integral parts of development policy and decision-making frameworks.

Potable water reuse history and a new framework for decision making

Joseph A. Cotruvo

Joseph Cotruvo & Associates, LLC, Washington, USA

ABSTRACT

As populations and water demand increase, more sustainable water sources are needed. Wastewater reuse is a major opportunity. Treated wastewater is available for non-potable applications and drinking water production. Direct potable reuse and planned indirect potable reuse provide sustainable drinking water; other reuse applications can offset current drinking water uses at lower cost due to lower end-use quality requirements. There is some public reluctance to choose potable reuse, but planned reuse projects provide drinking water of higher quality than typical natural sources. Guidance is available to assure safe and high-quality reused water.

Introduction

Water has always been reused for non-potable (e.g., industrial cooling or irrigation) and often for potable applications. Potable water reuse is not a new concept, but it has become a prime opportunity to provide high-quality drinking water in water-short areas where alternatives are not sufficient for population needs (Asano & Cotruvo, 2004). With the advent and refinement of better water treatment technologies, it is capable of yielding more efficient use of available natural water while providing water that is at least as safe and probably safer than local surface waters that are treated by conventional drinking water technologies (National Research Council [NRC], 2012).

Types of potable reuse have progressed over the centuries. Indirect potable reuse (IPR) occurs when waste discharges enter upstream and the mixed streamwater and wastewater is transported downstream to a drinking water intake, where it is usually treated to drinking water standards by conventional treatment technologies. Direct potable reuse (DPR) does not have the intermediate environmental passage and the waste stream is treated to drinking water quality using advanced treatment technologies and put into distribution to consumers with or without an engineered storage buffer (Cotruvo, 2014).The progression of potable reuse over time is summarized as follows:

• Unplanned or deliberate IPR: Untreated or treated upstream surface water discharge downstream to a municipal drinking water plant.
• Planned IPR with groundwater recharge: Soil aquifer treatment or injection of highly treated water into recoverable aquifers.
• Planned IPR: Advanced treated wastewater with surface discharge to a water body or groundwater recharge.
• IPR/DPR: Advance treated wastewater is discharged to the entry point of a drinking water treatment plant, or post-treatment blending, or storage in surface or groundwater prior to distribution.
• Pipe-to-pipe DPR: Treated wastewater is discharged to drinking water distribution without an environmental but possibly with an engineered storage buffer.

Before the 1970s many surface water sources in the United States were seriously contaminated because of uncontrolled wastewater and industrial discharges, resulting in microbial and chemical contamination of many surface waters. Major Clean Water Act legislation to control waste discharges was being implemented, beginning in 1972. This included: universal secondary treatment requirements for municipal wastewater discharges to surface waters; listings of priority industrial pollutants; initial implementation of pretreatment regulations; and National Pollution Elimination Discharge permits. These treatment requirements have prohibited discharge of billions of pounds of pollutants annually into US surface waters (Cotruvo, 2014).

The federal Safe Drinking Water Act of December 1974 (US Environmental Protection Agency [USEPA], 2015) was being implemented, beginning in 1976. Regulations for traditional inorganic, pesticide, radionuclide and microbial contaminants were being written and implemented. Regulations for trihalomethanes, disinfection by-products of chlorination, were in effect, and regulations on volatile industrial chemicals were being developed. Regulations for managing underground injection practices were being implemented to protect drinking water aquifers. Pesticide registration requirements were being developed, driven in part by the need to protect drinking water sources from contamination.

The US Environmental Protection Agency (EPA) began exploring potable reuse in 1980 with an expert workshop entitled Protocol Development: Criteria and Standards for Potable Reuse and Possible Alternatives (USEPA, 1980). Its purpose was to examine the state of the science of potable water reuse and to assess water quality, best available treatment technology, reliability, analytical chemistry, microbiology, toxicology, and human health issues. Since then, acceptance of DPR and the state of the scientific knowledge and technology have improved significantly.

Water technology

The conventional drinking water treatment for surface water sources at the time was coagulation, flocculation, sedimentation, sand filtration and chlorine disinfection. Powdered and granular activated carbon had applications for taste and odour control. Ozone and membranes were in their early stages. Microbial analyses consisted of total coliforms and E. coli or faecal coliforms, and heterotrophic plate counts. There was limited information on viruses and Giardia, and early indication of concerns for Cryptosporidium; polymerase chain reaction (PCR) was nonexistent. Analytical methods for trace organic chemicals were being developed and beginning to be applied in wastewater and drinking water facilities. Parts-per-billion measurements of organic chemicals were beginning to be applied to drinking water, but occurrence databases were very limited.

In 1980, the EPA initiated its interests in exploring direct potable reuse by organizing an expert workshop to review the issues and provide guidance on future directions. The workshop recommendations were:

• standards to define potable water regardless of source
• comprehensive characterization of source waters
• more toxicology study including concentrate studies
• better treatment technology with improved reliability and redundancy
• more implementation of groundwater recharge
• more non-potable reuse options.

Impediments included institutional, legal, and water rights issues and social and public acceptance of reuse (USEPA, 1980; Cotruvo, 2014). Thirty-five years later, much progress has been achieved.

• The state of science and technical understanding in the water industry has made major progress.
• Wastewater management and pretreatment have been instituted and the quality of wastewater has improved.
• Drinking water standards exist for almost 100 contaminants, plus broad treatment requirements for filtration and disinfection, as well as guidelines for hundreds of chemicals.
• Sophisticated instruments and analytical methods now allow quantitation at parts per trillion and lower levels, including more real-time on-line methods.
• Treatment technology now includes biological activated carbon, MF, UF, NF, and RO membranes, and advanced oxidation and ion-exchange resins.

Examples of advanced IPR and DPR potable reuse projects now operating or being developed and their treatment components are listed below (Cotruvo, 2014)

Windhoek, Namibia

• 1969 – FeCl₃, coagulation, dissolved air flotation, rapid sand, GAC, Cl_2, NaOH, blend (now considered non-potable; irrigation only)
• 1997 – PAC, pre-O₃, FeCl₃/polymer, coagulation, dissolved air flotation, KMnO₄, rapid sand, O₃, BAC, GAC, UF, Cl_2, NaOH, blend (about 30% recycled water)

NASA – International Space Station

• Urine distillate and air condensate recovery
• Multifiltration, vapour compression distillation, catalytic reactor, ion exchange, iodine

Big Spring, Texas

• Chlorinated secondary effluent, granular media → MF, RO, advanced oxidation, blend → flocculation, sedimentation, granular media, disinfection → distribution (issue: high salinity in natural source)

Singapore NEWater

• Secondary treated wastewater, UF, RO, UV

Orange County, California

• Groundwater replenishment and seawater intrusion barrier, 100 million gallons per day (mgd)
• Secondary effluent, NH₂Cl, MF, cartridge filter, RO (three-stage), H₂O₂/UV advanced oxidation, strip CO₂, lime stabilization

Domestic/commercial potable recycling

• Pure Cycle, Colorado, 1976–1982 – household wastewater, grinder, biodisk/cloth filter, MF, IX, UV → household storage tank
• Tangent Company in Ohio is developing and evaluating a single-building DPR system.

(Abbreviations in the preceding: GAC = granular activated carbon; PAC = powdered activated carbon; BAC = biological activated carbon; MF = microfiltration; IX = ion exchange; UF = ultrafiltration; NF = nanofiltration; RO = reverse osmosis; UV = ultraviolet light.)

Water reuse policy development

The past development of wastewater treatment philosophy has been to collect, process and dispose of wastewater so as to not injure the water environment. That is now being radically changed to considering wastewater as an asset to be exploited for all of the recoverable resources it contains, including the water itself (Cotruvo, 2012). From a public policy perspective DPR is a merging of the traditionally separate processes and organizations of wastewater treatment and drinking water provision. That creates a need to integrate the thought processes of the two disciplines and retrain many operators. DPR is intended to augment existing drinking water supplies that are already subject to drinking water regulations. Because of the intensive treatment, DPR product water is likely to be comparable or higher in quality than the existing water supply.

Recycled drinking water is drinking water, and should be subject to the same quality requirements as any other drinking water. Although DPR water is derived from an impaired water source, the technology is specifically designed to produce water of higher quality than many conventional drinking water systems, and with greater management oversight and more safeguards. Regulators will need to be educated on the benefits, safety and opportunities provided by DPR so that regulatory requirements will be appropriate to the new technology and its capabilities, while reflecting the reality that day-to-day operations require a higher level of diligence and qualifications.

Most countries do not currently have specifications that apply uniquely to direct potable reuse; Australia is an exception (Australia, 2006). A few states in the US have initiated guidelines and standards development. The EPA has published a compilation of water reuse activities and information (USEPA, 2012), and the International Life Sciences Institute has published guidelines for potable reuse in beverage processing (International Life Sciences Institute [ILSI], 2013).

There are two recent and current activities aimed at providing state-of-the-art background information and a set of principles to assist entities in developing standards for process decisions and standards. In the US a small expert group has produced a comprehensive Framework for Direct Potable Reuse (WateReuse Research Foundation [WRRF], 2015). It was initiated by the WateReuse Association’s National Regulatory Committee and cosponsored by the WateReuse Association, American Water Works Association, Water Environment Foundation and National Water Reuse Institute. And the World Health Organization has recently begun a process to develop potable water reuse guidelines, which are expected to be available for review in 2017 (World Health Organization [WHO], 2015).

Framework for direct potable reuse

The WateReuse framework provides a policy structure for decision making for the introduction, design, management and regulatory oversight of planned DPR. DPR is intended to supplement and enhance the availability of adequate high-quality water supplies while assuring compliance with regulatory requirements. The focus of the framework document is: (1) to provide a discussion of what guidance would be required in each of the three key components that make up a direct potable reuse programme; and (2) to assist decision makers in understanding the role DPR projects can play in a community’s overall water portfolio. The three components require an understanding and approach to address regulations, technology, and public involvement.

(1) Regulations

1. Identifying potential public health risks and appropriate measures for their mitigation
2. Defining the elements of a regulatory permitti...