e Pergamon Wal. Sci. Tech. Vol. 33, No. 10-11, pp. 451-462, 1996.Copyright © 1996 IAWQ. Published by Elsevier Science Ltd

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WATER RECLAMATION AND REUSECRITERIA IN THE U.S.

James Crook* and Rao Y. Surampalli**

* Black & Veatch, 100 Cambridge Park Drive, Cambridge, MA 02140, USA** U.S. Environmental Protection Agency, P.O. Box 17-2141, Kansas City, KS 66117,USA

ABSTRACT

reasing demands on water resources for domestic, commercial, industrial, and agricultural purposesIe made water reclamation and reuse an attractive option for conserving and extending availableter supplies. Also, many water reuse projects are implemented to eliminate a source of contaminationsurface waters or as a least-cost alternative to meeting stringent discharge requirements. Reclaimedler applications range from pasture irrigation to augmentation of potable water supplies. Water:lamation and reuse criteria are principally directed at health protection. There are no federal:ulations governing water reuse in the U.S.; hence, the regulatory burden rests with the individualtes. This has resulted in differing standards among states that have developed criteria. This papernmarizes and compares the criteria from some states that have developed comprehensive regulations.idelines published by the US. EPA and the rationale behind them are presented for numerous typesreclaimed water applications. Copyright © 1996 IAWQ. Published by Elsevier Science Ltd.

KEYWORDS

alth standards; microbiological limits; reclaimed water; regulations; standards; wastewater reuse;ter quality criteria; water reclamation; water reuse; water reuse criteria.

INTRODUCTION

cause there are no federal regulations governing water reclamation and reuse in the U.S., the:ulatory burden rests with the individual states. The first water reclamation and reuse standards were)pted by the State of California in 1918 and addressed the use of reclaimed water for agriculturaligation. California continually revised its water reuse standards since that time to address additional:laimed water applications, advances in wastewater treatment technology, and increased knowledge in:areas of microbiology and public health protection. As water reuse became recognized as an integralnponent in water resources management in other parts of the country, several other states havelowed California's lead and developed water reclamation and reuse regulations. The criteria varylong the states that have developed regulations, and some states have no regulations or guidelines.me states have regulations or guidelines directed at land treatment or land application for furtheratment or as a means of wastewater disposal rather than regulations oriented to the intentionalleficial use of reclaimed water, even though the effluent may be used for irrigation of agricultural~s, golf courses, or public access lands. No states have regulations that cover all potential uses of:laimed water and no states currently have comprehensive criteria addressing potable reuse, althoughlifornia and Florida are developing criteria addressing indirect potable reuse. In recognition of the.ue of reclaimed water, the US. EPA published guidelines in 1992 that are intended to provideldance to states that have not developed their own criteria or guidelines.

451

1. CROOK and R. Y. SURAMPALLI

OLUTION OF WATER REUSE REGULATIONS

Although agricultural irrigation with low quality wastewater was practiced in some areas of the U. S. inthe late 1800s, there were no significant regulations or restrictions on the practice until the early part ofthe 20th century. As urban areas began to encroach on sewage farms and as the scientific basis ofdisease became more widely understood, concern about the possible health risks associated withirrigation using wastewater grew among public health officials. This led to the establishment ofguidelines and regulations to control the use of wastewater for agricultural irrigation, which was thefirst reclaimed water application to be regulated.

The early history of public health in the environmental field was one of efforts to provide safe watersupply and safe disposal of wastewater. With the latter, the first efforts were directed at eliminatingindiscriminate discharges of raw sewage to the environment and at providing wastewater treatment.These efforts progressed to providing higher levels of treatment; in particular, biological oxidation torestore receiving waters to aerobic conditions and disinfection of effluents to protect against healthhazards from public contact with recreational waters.

Standards for acceptable performance evolved from these practices - standards that represented goodpractice, that could be attained by well designed and operated treatment plants, and that were validatedby indications that the resulting conditions were no longer producing epidemic disease. Hence,standards evolved as part of the process to cleanup major public health hazards associated with domesticwater supply and municipal wastewater disposal. The evolution of regulations pertaining to water reusefollowed the same pattern. Advances in treatment technology, water quality monitoring, and riskassessment in the last 20 years have provided a scientific basis for rational water reclamation and reusecriteria.

FACTORS AFFECTING CRITERIA DEVELOPMENT

Key factors in the establishment of water reclamation and reuse criteria include health protection, publicpolicy, past reuse experience, technical feasibility, and economics. While there have been nodocumented disease outbreaks resulting from the use of reclaimed water in the U.S., adverse healthconsequences associated with the reuse of raw or improperly treated wastewater in other countries arewell documented (Sepp, 1971; Lund, 1980; Feachem et ai., 1983; Shuval et ai., 1986). As a result,water reuse standards and guidelines for nonpotable reuse are directed principally at public healthprotection and generally are based on the control of pathogenic organisms. Health risks associated withboth pathogenic microorganisms and chemical constituents need to be addressed where reclaimed wateris used for indirect potable water supply augmentation.

IThe acceptability of reclaimed water for any particular use is dependent on the physical, chemical, andmicrobiological quality of the water. Factors that affect the quality of reclaimed water include sourcewater quality, wastewater treatment processes and treatment effectiveness, treatment reliability, anddistribution system design and operation. Most states require implementation of industrial sourcecontrol programs to limit the input of chemical constituents that may adversely affect biologicaltreatment processes and subsequent acceptability of the water for specific uses. Assurance of treatmentreliability is an obvious, yet sometimes overlooked, quality control measure. Distribution system designand operation is important to assure that the reclaimed water is not degraded prior to use and not subjectto misuse. For example, open stor~ze may result in water quality degradation by micro-organisms,algae, or particulate matter, and may cause objectionable odor or color in the reclaimedwater.

The presence of toxic chemicals and pathogenic microorganisms in wastewater creates the potential foradverse health effects where there is contact, inhalation, or ingestion of chemical or microbiological

Water reclamation and reuse criteria in the U.S. 453

stituents of health concern. EffecIs of physical parameters, e.g., pH, color, temperature, andticulate matter, and chemical constituents, e.g., chlorides, sodium, and heavy metals, are wet',wn, and recommended limits have been established for many constituents (National Academy of:nces-National Academy of Engineering, 1973; US. EPA, 1981; Westcot and Ayers, 1985; Waterlution Control Federation, 1989). However, the effect of organic constituents in reclaimed waterd for crop irrigation may warrant attention if industrial wastes contribute a significant fraction to theitewater. Health risks associated with microbiological agents are more difficult to assess. This is.ected in differing reclaimed water requirements and guidelines among the states.

tes that have water reuse regulatiCi.~s or guidelines typically set standards for reclaimed water qualityl specify minimum treatment requirements. The most common parameters for which water qualityits are imposed are biochemical oxygen demand (BOD), turbidity or total suspended solids (TSS),II or fecal coliform bacteria, nitrogen, and chlorine contact time and residual.

lere reclaimed water is used in an urban setting, most states require a high degree of treatment andinfection. Where there is likely to be public contact with the reclaimed water, tertiary treatment tolduce finished water that is essentially pathogen-free is typically required (State of California, 1978;lrida Department of Environmental Regulation, 1990; State of Arizona, 1991). EPA's Guidelines jorIter Reuse recommends similar treatment and quality for reclaimed water use in urban areas (US.'A,1992).

claimed water used inside buildings for toilet and urinal flushing or for fire protection presents cross•mection control concerns. Although such uses do not result in frequent human contact with theter, regulatory agencies usually require that the reclaimed water be essentially pathogen-free toluce health hazards upon inadvertent cross-connection to potable water systems (Florida DepartmentEnvironmental Regulation, 1990; Pawlowski, 1992; State of California, 1994a).

lile the need to maintain a chlorine residual in reclaimed water distribution systems to prevent odors,nes, and bacterial regrowth was recognized early in the development of dual water systems (Okun,79), only recently have regulatory agencies begun to require such residuals. In Washington, forlmple, criteria require maintenance of a chlorine residual in distribution systems carrying reclaimedter (State of Washington, 1993). The Guidelines for Water Reuse recommend that a chlorine residualat least 0.5 mg/L be maintained in reclaimed water distribution lines.

lte-Mandated Reuse

California and Florida, where water reclamation and reuse is well-established and the value oflaimed water has been recognized, laws and. regulations exist that mandate water reuse under certainlditions.

e California Water Code states thai. the use of potable domestic water for nonpotable uses, including,: not limited to, cemeteries, golf courses, highway landscaped areas, and industrial and irrigation:s, is a waste or an unreasonable use of the water if reclaimed water is available which meets certainlditions (State of California, 1994b). The conditions are: (a) the source of reclaimed water is of:quate quality for these uses and is available for these uses; (b) the reclaimed water may be furnishedthese uses at a reasonable cost to the user; (c) after concurrence with the State Department of Health~vices, the use of reclaimed water from the proposed source will not be detrimental to public health;I (d) the use of reclaimed water for these uses will not adversely affect downstream water rights, will:degrade water quality, and is determined not to be injurious to plant life, fish and wildlife.

e Water Code mandates that no person or public agency shall use water from any source or qualitytable for potable domestic use for nonpotable uses if suitable reclaimed water is available and meetsconditions stated above. Other sections of the code allow for mandating reclaimed water use for

454 1. CROOK and R. Y. SURAMPALLI

irrigation of residential landscaping, industrial cooling applications, and toilet and urinal flushing innonresidential buildings (State of California, 1994b). Some local jurisdictions in the state also havetaken action to require the use of reclaimed water in certain situations. For example, the Irvine RanchWater District enacted an ordinance in 1990 requiring all new buildings higher than 17 m (55 ft) toinstall a dual distribution system for toilet flushing in areas where reclaimed water is available (IrvineRanch Water District, 1990).

The Florida Water Policy (Florida Department of Environmental Regulation, 1988) establishes amandatory reuse program. The policy requires that the state's water management districts identify"critical water supply problem areas" that currently exist or are anticipated to exist during the next 20years. Reuse of reclaimed water from municipal wastewater treatment facilities is required within thedesignated critical water supply problem areas unless reuse is not economically, environmentally, ortechnically feasible. The water management districts can require reuse of reclaimed water if thereclaimed water is readily available and the water management district has adopted rules for reuse inthose areas.

Florida has developed Guidelines for Preparation of Reuse Feasibility Studies for Applicants HavingResponsibility for Wastewater Management (Florida Department of Environmental Regulation, 1991).The document provides comprehensive requirements for the preparation of reuse feasibility studies. Thefeasibility evaluation must include economic considerations, reuse benefits, and technical feasibility.

WATER RECLAMATION AND REUSE CRITERIA

No states have regulations that cover all potential uses of reclaimed water, but several states haveextensive regulations or guidelines that prescribe requirements for a wide range of end uses of thereclaimed water. Other states have regulations or guidelines that focus on land treatment of wastewatereffluent, emphasizing additional treatment or effluent disposal rather than beneficial reuse, even thoughthe effluent may be used for irrigation of agricultural sites, golf courses, or public access lands. Theabsence of state criteria for specific reuse applications does not necessarily prohibit those applications;many states evaluate specific types of water reuse on a case-by-case basis.

Several states with active reuse programs, e.g., Arizona, California, Florida, and Texas, havecomprehensive regulations and prescribe requirements according to the end use of the water. There aredifferences among these requirements, such as: California uses total coliform as the indicator organism,while the other three states use fecal coliform; Florida is the only one of the four states that requiresmonitoring for total suspended solids to determine particulate levels - the other four states use turbidity;California and Florida prescribe treatment processes in addition to water quality limits, while Arizonaand Texas do not specify treatment processes, although Arizona is considering the inclusion oftreatment process requirements in the state's reuse regulations (Pawlowski, 1992); and Arizona andCalifornia permit the use of reclaimed water for spray irrigation of food crops eaten raw, while suchuse is prohibited in Florida and Texas.

Water reclamation and reuse criteria for California and Florida are summarized below.

California

The State of California has a long history of water reclamation and reuse and developed the first waterreuse regulations in the U.S. in 1918. These have been modified and expanded through the years. Thestate's current Wastewater Reclamation Criteria (State of California, 1978), which are in the process ofbeing revised, were adopted by the Department of Health Services (DHS) in 1978. The reclamationcriteria include water quality standards, treatment process requirements, operational requirements, andtreatment reliability requirements. The treatment and quality criteria summarized in Table 1 include the

Water reclamation and reuse criteria in the U.S.

TABLE 1. CALIFORNIA TREATMENT AND QUALITY CRITERIAa FOR NONPOTABLEUSES OF RECLAIMED WATER

455

Type of Use

Irrigation of fodder, fiber, & seed crops,orchards and vineyardsC

, and processed foodcrops; flushing sanitary sewers

Irrigation of Pfsture for milking animals,landscape areas , ornamental nursery stock,and sod farms; landscape impoundments;industrial or commercial cooling waterwhere no mist is created; nonstructural firefighting; industrial boiler feed; soilcompaction; dust control; cleaning roads,sidewalks, and outdoor areas

Surface irrigation of food crops; restrictedlandscape impoundments

Irrig~tion of food cropse and landscapeareas; nonrestricted recreational impound•ments; toilet and urinal flushing; industrialprocess water; decorative fountains; com•mercial laundries; snow-makIng; structuralfire fighting; industrial or commercialcooling where mist is created

Total ColitormLimits

None required

23/100 mL

2.2/100 mL

2.2/100 mL

TreatmentRequired

Secondary

Secondary &disinfection

Secondary &disinfection

Secondary,coagulation,clarificat~ong,filtration , &disinfection

: Includes proposed revisions.Based on running 7-day median.

: No contact between reclaimed water and edible portion of crop.Cemeteries, freeway landscaping, restricted access golf courses, and other controlled accessirrigation areas.

eContact between reclaimed water and edible portion of crop; includes edible root crops.f Parks, playgrounds, schoolyards, residential landscaping, unrestricted access golf courses,

and other uncontrolled access irrigation areas.gExcept for nonrestricted recreational impoundments and cooling uses where mist is created,

coagulation is not required if the turbidity prior to filtration does not exceed 5 NTU.h The turbidity of filtered effluent cannot exceed an average of 2 nephelometric turbidity units

(NTU) during any 24-hour period.

Source: State of California (1994a).

~st proposed revisions to the Wastewaier Reclamation Criteria. Coliform samples must be collected atst daily and compliance is based on a running seven-day median number. Turbidity and chlorineidual must be monitored continuously. The proposed regulations require that reclaimed water used, nonrestricted recreational impoundments must be monitored for enteric viruses, Giardia, andyptosporidium during the first two years of operation if the treatment chain does not include aIimentation unit process between the coagulation and filtration processes.

e Wastewater Reclamation Criteria also include requirements for treatment reliability. The reliabilityluirements address standby power supplies, alarm systems, multiple or standby treatment processits, emergency storage or disposal of inadequately treated wastewater, elimination of treatment)cess bypass, monitoring devices and automatic controllers, and flexibility of design.

e proposed revisions to the reclamation criteria include the following reclaimed water use arealuirements: no irrigation or impoundment of undisinfected reclaimed water within 50 m (150 ft) of, domestic water supply well; no irrigation of disinfected secondary-treated reclaimed water within

1. CROOK and R. Y. SURAMPALLI

30 m (100 ft) of any domestic water supply well; no irrigation with tertiary-treated (secondarytreatment, filtration, and disinfection) reclaimed water within 15 111 (50 ft) of any domestic water supplywell, and no impoundment of tertiary-treated reclaimed water within 30 m (100 ft) of any domesticwater supply well; only tertiary-treated reclaimed water can be sprayed within 30 m (100 ft) of aresidence or places where more than incidental exposure is likely; runoff must be confined to thereclaimed water use area; drinking water fountains must be protected against contact with reclaimedwater; signs, e.g., RECLAIMED WATER - DO NOT DRINK, at sites using reclaimed water;prohibition of hose bibbs on reclaimed water irrigation systems; prohibition of direct connectionsbetween public water supply systems and reclaimed water systems; and backflow prevention devices onpublic water systems at sites receiving both potable and reclaimed water (State of California, 1994a).

The 1978 Wastewater Reclamation Criteria inciude general requirements for groundwater recharge ofdomestic water supply aquifers by surface spreading. The regulations state that reclaimed water used forgroundwater recharge of domestic water supply aquifers by surface spreading "shall be at all times of aquality that fully protects public health" and that DHS recommendations "will be based on all relevantaspects of each project, including the following factors: treatment provided; effluent quality andquantity; spreading area operations; soil characteristics; hydrogeology; residence time; and distance towithdrawal. "

While aspects of its regulatory development process has been protracted, California has developed acomprehensive approach to groundwater recharge with treated municipal wastewater. Currently•proposed regulations have gone through several iterations and, when finalized, will replace the generalregulations for groundwater recharge in the Wastewater Reclamation Criteria. The proposed regulationsaddress both surface spreading and injection projects and are focused on indirect potable reuse of therecovered water. Treatment requirements and performance standards are proposed for each type ofproject. They also address water quality standards, recharge methods, operational controls, distance towithdrawal, time in the underground, and monitoring wells. A summary of the proposed treatmentprocess and site requirements is presented in Table 2.

TABLE 2. PROPOSED GROUNDWATER RECHARGE CRITERIA IN CALIFORNIA

150 150 300 600(500 ft) (500 ft) (1000 ft) (2000 f

Project CategorlI II III IV

Xb X X XX X XX X X XX X50 20 20 50

Treatment and RechargeSite RequirementsRequired treatment

SecondaryFiltrationDisinfectionOrganics removal

Maximum allowable reclaimedwater in extracted well water (%)Depth to groundwater (m) atinitial percolation rate of:

<0.5 cm/min «0.2 in/min)<0.8 cm/min «0.3 in/min)

Minimum retention timeunderground (months~

Horizontal separation (m)

3 (10 ft) 3 (10 ft) 6 (20 ft)6 (20 ft) 6 (20 ft) 15 (50 ft)

6 6 12

cn.a.cn.a.

12

a Cat~gories I, II, and III are for surface spreading projects. Category IV is for injectionprojects.

b X means that the treatment process is requiredC Not applicable.d From edge of recharge operation to the nearest potable water supply well.

Source: State of California (1993).

The proposed regulations prescribe stringent microbiological and chemical constituent limits. Forspreading operations, credit is given for reduction or removal of chemical constituents and pathogenic

Water recl,unation and reuse criteria in the U.S. 457

:roorganisms during percolation through the vadose zone, and the percolated water must bemtially pathogen-free and meet drinking water maximum contaminant levels after percolation)ugh the vadose zone. In contrast, injected water must all required water quality limits at the point of:ction. The proposed regulations specify total organic carbon (TOC) as a surrogate for unregulatedanics that may be of concern. Although TOC is not a measure of specific organic compounds, it islsidered to be a suitable measure of gross organics content of reclaimed water for the purpose ofermining organics removal efficiency in practice. Based principally on information contained in aort prepared by a Scientific Advisory Panel on Groundwater Recharge with Reclaimed Water (StateCalifornia, 1987), DHS concluded that extracted groundwater should contain no more than 1 mg/LC of wastewater origin. This decision is reflected in maximum allowable TOC concentrations in thelaimed water prior to spreading or injection.

.teria for indirect potable reuse via surface water augmentation have not been developed in CaliforniaI will be considered on an individual case basis. A proposal to use reclaimed water for indirect.able reuse via surface water augmentation in San Diego County has been given conceptual approvalDHS as a demonstration project (Collins, 1994).

)rida

ltil recently, the primary driving force behind implementation of reuse projects in Florida wasluent disposal. Rule 17-610, Florida Administrative Code, "Reuse of Reclaimed Water and Landplication", was adopted in 1989 and revised in 1990 (Florida Department of Environmentalgulation, 1990). The existing regulations are currently under revision, due in part to an increasingareness of the importance of water reuse in helping to meet the water needs of the state. Treatment1quality criteria, including proposed revisions, for nonpotable uses of reclaimed water are shown inble 3.

TABLE 3. FLORIDA TREATMENT AND QUALITY CRITERIAa FOR NONPOTABLEUSES OF RECLAIMED WATER

Public access areasc, food

crop irrigationd, toilet

flushinge, re-creational

impoundmentsf, fire

protection, aesthetic purposes,dust control

Type of UseRestricted publicareasb

, industrial usesaccess

Water Quality Limits200 fecal coli/IOO mL20 mg/L TSS20 mg/L BODNo detectable fecalcoli/100 mL5 mg/L TSS20 mg/L BOD

Treatment RequiredSecondary &disinfection

Secondary,filtration, &disinfection

a Includes proposed revisions.b Sod farms, forests, pasture land, areas used to grow trees and fodder, fiber, and seed

crops, or similar areas.. "C Residential lawns, golf courses, cemetenes, parks, landscaped areas, hIghway medIans, or

similar areas.d Only allowed if crops are peeled, skinned, cooked, or thermally processed before

consumption.e Only allowed where residents do not have access to plumbing system. Not allowed in

single-family residences.f For full body contact imp.o~ndmen~s, reclaimed wat~r must m~et drinking water

bacteriological standards If It constitutes > 50 % of mflow to Impoundment.

Source: Florida Department of Environmental Protection (1995).

addition to the wastewater treatment and water quality requirements presented in Table 3, Florida's:ulations contain design and use area requirements including the following: minimum system size of) m3/d (0.1 mgd) for any irrigation system; operating protocol that includes continuous turbidity and

45~ J. CROOK and R. Y. SURAMPALLI

chlorine monitoring; minimum system storage of at least 3 days if no backup system is provided; prohi•bition of cross-connections with potable systems; backflow prevention devices on potable water linesentering property served by reclaimed water systems; ordinances or user agreements to documentcontrols on individual users; use area controls, including groundwater monitoring, surface runoffcontrol, public notification, and setback distances. Florida requires a minimum 23-m (75-ft) setbackfrom areas irrigated with highly disinfected reclaimed water containing no detectable fecalcoliforms/loo mL to potable water supply wells, but no setbacks to surface water or developed areasare required when this quality of reclaimed water is used. Other setback distances depend on reclaimedwater quality and range up to 150 m (500 ft) at areas receiving reclaimed water that must meet a fecalcoliform limit of 200/100 mL.

The existing regulations include sections addressing rapid-rate land application systems and absorptionfield systems, both of which result in groundwater recharge. The reclaimed water treatment and qualityrequirements for systems that recharge drinking water supply aquifers are similar to, but generallyslightly less restrictive than, those !n the California regulations for surface spreading of reclaimedwater. Proposed revisions to the Florida regulations include criteria directed at planned indirect potablereuse by injection into water supply aquifers and augmentation of surface supplies. The proposedinjection regulations are similar to the proposed California regulations addressing injection of reclaimedwater. They specify that reclaimed water meet drinking water standards, require activated carbonadsorption as an organics removal process, and limit the average TOC to 3.0 mg/L or less in theproduct water. The proposed treatment and water quality requirements for reclaimed water used toaugment surface waters are not as restrictive as those for reclaimed water used for injection.

us. EPA WATER REUSE GUIDELINES

The US. EPA, in conjunction with the U.S. Agency for International Development, publishedGuidelines for Water Reuse in 1992 (US. EPA, 1992). The primary purpose of the document is toprovide guidelines, with supporting information, for utilities and regulatory agencies in the U.S.,particularly in states where standards do not exist or are being revised or expanded. The guidelinesaddress water reclamation and reuse for nonpotable urban, industrial, and agricultural applications aswell as indirect potable reuse by groundwater recharge and augmentation of surface water sources ofsupply.

The guidelines address all important aspects of water reuse and include recommended treatmentprocesses, reclaimed water quality limits, monitoring frequencies, setback distances, and other controlsfor various water reuse applications. The treatment processes and reclaimed water quality limitsrecommended in the guidelines for various reclaimed water applications are given in Table 4.

Both reclaimed water quality limits and wastewater treatment unit processes are recommended for thefollowing reasons: water quality criteria involving surrogate parameters do not adequately characterizereclaimed water quality; a combination of treatment and quality requirements known to producereclaimed water of acceptable quality obviate the need to monitor the finished water for certainconstituents; expensive, time-consuming, and in some cases, questionable monitoring for pathogenicmicroorganisms is eliminated without compromising health protection; and treatment reliability isenhanced (US. EPA, 1992).

In the U.S., total and fecal coliforms are the most commonly used indicator organisms in reclaimedwater. The total coliform analysis includes organisms of both fecal and nonfecal origin, while the fecalcoliform analysis is specific for coliform organisms of fecal origin. Therefore, fecal coliforms are betterindicators of fecal contamination than total coliforms , and the guidelines use fecal coliform as theindicator organism. Either the membrane filter technique or the multiple-tube fermentation techniquemay be used to quantify the coliform levels in the reclaimed water.

Water reclamation and reuse criteria in the U.S.

TABLE 4. US. EPA GUIDELINES FOR WATER REUSE

459

Type of Use

Urban uses, irrigation offood crops eaten raw,recreational impound•ments

Irrigation of restrictedaccess areas and processedfood crops, aesthetic im•poundments, constructi~n

uses, industrial cooling,environmental reuse

Groundwater recharge ofnonpotable aquifers byspreading

Groundwater recharge ofnonpotable aquifers byinjection

Groundwater recharge ofpotable aquifers byspreading

Groundwater recharge ofpotable aquifers by in•jection, augmentation ofsurface supplies

Treatment

Secondary,filtration, &disinfection

Secondary &disinfection

Site specific &use dependent,primary (minimum)

Site specific &use dependent,~econdary (minimum)

Site specific,secondary &disinfection (minimum)

Includes the following:secondary, filtration,disinfection, advancedwastewater treatment

Reclaimed Water Quality

pH = 6-9s 10 mg/L BODs 2 NTUa

No detectable fecal coli/IOO mLb

~ 1 mg/L Cl2 residualc

pH = 6-9s 30 mg/L BODs 30 mg/L SSs 200 fecal coli/IOO mLe

~ 1 mg/L Cl2 residuat

Site specific & use dependent

Site specific & use dependent

Site specificMeet drinking water standards afterpercolation through vadose zone

Includes the following:pH = 6.5-8.5

s 2 NTUa

No detectable fecal coli/IOO mLb

~ 1 mg/L Cl2 residualc

Meet drinking water standards

: 24-hour average value. Should not exceed 5 NTU any time. Should be met prior to disinfection.Based on a 7-day median value. Should not exceed 14 fecal coli/IOO mL in any sample.

C After a minimum contact time of 30 minutes.d Recirculating cooling towers.e Based on 7-day median value. Should not exceed 800 fecal coli/IOO mL in any sample.

Source: US. EPA (1992).

~ guidelines include limits for fecal coliform organisms but do not include parasite or virus limits.'asites have not been shown to be a problem at reuse operations in the U.S. at the treatment levelsI reclaimed water limits recommended in the guidelines, although there has been considerable interestrecent years regarding the occurrence and significance of Giardia and Cryptosporidium in reclaimedler. Where filtration and a high level of disinfection are recommended in Table 4 to producelaimed water that is essentially pathogen-free, including the parasites Giardia and Cryptosporidium,lay be necessary to provide chemical addition prior to filtration.

lite viruses are a concern in reclaimed water, virus limits are not recommended in the guidelines forfollowing reasons: a significant body of information exists indicating that viruses are inactivated orloved to low or immeasurable levels via appropriate wastewater treatment (Sanitation Districts ofi Angeles County, 1977; Engineering-Science, 1987; Crook, 1989); the identification and.meration of viruses in wastewater are hampered by relatively low virus recovery rates; there are aited number of facilities having the personnel and equipment necessary to perform the analyses; thelratory analyses can take as long as 4 weeks to complete; there is no consensus among public health

460 1. CROOK and R. Y. SVRAMPALLI

experts regarding the health significance of low levels of viruses In reclaimed water; and there have notbeen any documented cases of viral disease resulting from the reuse of wastewater in the U.S. Whilerecent advances in recombinant DNA technology have provided new tools to rapidly detect viruses inwater, e.g., nucleic acid probes and polymerase chain reaction technology, these new methods are notable to quantify viruses or differentiate between infective and non-infective virus particles (Yates,1993). Improvements will have to be made before these methods can be put into general use fordetecting viruses and other pathogens in environmental samples.

Unplanned or incidental indirect potable reuse occurs in many states in the U.S., while planned orintentional indirect potable reuse via groundwater recharge or augmentation of surface supplies is lesswidely practiced. Whereas the water quality requirements for nonpotable water uses are tractable andnot likely to change significantly in the future, the number of water quality constituents to be monitoredin drinking water (and, hence, reclaimed water intended for potable reuse) will increase and qualityrequirements are likely to become more restrictive. Consequently, it would not be prudent to suggest acomplete list of reclaimed water quality limits for all constituents of concern (U.S. EPA, 1992). TheEPA guidelines provide some general and specific information to indicate the extensive treatment andwater quality requirements that are likely to be imposed where indirect potable reuse is contemplated.The EPA guidelines do not advocate direct potable reuse and do not include recommendations for suchuse.

The EPA guidelines include recommended water quality limits other than those specified in Table 4.The guidelines document includes suggested chemical constituent limits for most of the uses presentedin Table 4. For example, for urban uses of reclaimed water, the guidelines recommend that the productwater be nontoxic upon ingestion. This is recommended to protect against inadvertent and infrequentingestion; it is not meant to imply that wastewater meeting the requirements for urban reuse isacceptable as a source of potable water. Other recommendations addressing urban use of reclaimedwater include the following: clear, colorless, and odorless product water; a setback distance of 15 m (50ft) from irrigated areas to potable water supply wells; maintenance of a chlorine residual of at least 0.5mg/L in the distribution system; treatment reliability and emergency storage or disposal ofinadequately-treated water; and cro;,s-connection control via reduced pressure principle backflowprevention devices on potable water service lines and color-coded or taped reclaimed water lines andappurtenances. Similar design and operational recommendations are included in the guidelines for thereclaimed water applications presented in Table 4.

It is explicitly stated in the Guidelines for Water Reuse that the recommended treatment unit processesand water quality limits presented in the guidelines "are not intended to be used as definitive waterreclamation and reuse criteria. They are intended to provide reasonable guidance for water reuseopportunities, particularly in states that have not developed their own criteria or guidelines." (US. EPA,1992).

SUMMARY

Several states in the U.S. have independently developed water reclamation and reuse criteria and, as aconsequence, there is considerable ';~riation among the different state regulations. Only a few states,such as California and Florida, have comprehensive regulations addressing most facets of water reuse.The US. EPA published Guidelines for Water Reuse in 1992 in an effort to provide guidance to utilitiesand regulatory agencies in states where standards do not exist or are being revised or expanded.Research is needed to resolve issues related to reuse criteria. Research needs include microbial riskassessment modeling, identification of new indicators of pathogenic microorganisms, real-time on-linemonitoring of parameters of concern, evaluation of the effects of process selection on particle-sizedistribution in wastewater, evaluation of alternatives to chlorine for disinfection, and continuing studyof the concentration and health significance of trace levels of organic chemical constituents in reclaimed

Water reclamation and reuse criteria in the U.S.

:er used for potable purposes.

REFERENCES

461

Ilins, H. (1994). Letter from Harvey Collins, California Department of Health Services, to PeterMacLaggan, San Diego County Water Authority, dated August 31, 1994.

>ok, J. (1989). Viruses in Reclaimed Water. In: Proceedings of the 63rd Annual TechnicalConference, pp. 231-237, sponsored by the Florida Section American Water Works Association,Florida Pollution Control Association, and Florida Water and Pollution Control OperatorsAssociation, November 12-15, St. Petersburg Beach, Florida.

gineering-Science. (1987). Monterey Wastewater Reclamation Study for Agriculture: Final Report.Prepared for the Monterey Regional Water Pollution Agency by Engineering-Science, Berkeley,California.

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