WATER QUALITY CONSIDERATIONS FOR NONPOTABLE WATER REUSE

5 9 5 3 9 Norwell, Massachusetts Pa*,-

James Crook Water Reuse Consultant

Paul Gorder Vice President

Camp Dresser & McKee Inc. Denver, Colorado

Introduction

Reclaimed water lhas been successfully used for a wide range of nonpotable applications in the US., many of which are listed in Table 1. The acceptability of reclaimed water for nonpotable uses depends on several factors, including the physical, chemical, and microbiological quality of the water. Depending on the intended use, considerations may include health protection, user requirements, irrigation effects, environmental effects, aesthetics, and public andlor user perception of the ireuse concept. Making reclaimed water suitable and safe for nonpotable reuse applications is achieved by eliminating or reducing the concentrations of inicroorganisms and chemical constituents of concern through wastewater treatment andlor by limiting limiting public or worker exposure to the water via design oir operational controls.

The impacts or constraints on reuse from physical parameters (e.g., pH, color, temperature, and particulate matter), and chemical constituents (e.g., chlorides, sodium, heavy metals, and some trace organic compounds), are well known and recommended limits have been established for many of these constituents.’4 The health risks associated with microbiological organisms are more difficult to assess.

Water reuse regulations vary widely among the states in the US. Some states have regulations or guidelines directed at land treatment or land application as a means for further wastewater treatment rather than regulations oriented to the intentional beneficiial use of reclaimed water. Several states have no regulations or guidelines, and others disallow reuse altogether. As might be expected, water- short states such (IS Arizona, Califomia, Florida, and Texas, have comprehensive water reclamation and reuse regulations. In recognition of the value of reclaimed water, the US. Einvironmental Protection Agency (EPA) published water reuse guidelines5 in 1992 that are intended to provide guidance to states that have not developed their own criteria or guidelines.

Water Qualii Considerations: Microorganisms

The principal infectious agents in wastewater can be classified into three broad groups: bacteria, parasites (protozoa and helminths), and viruses. Table 2 lists many of the infectious agents potentially present in raw municipal wastewater, and some of the impofitant waterborne pathogens are discussed below.

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Bacteria

One of the most common pathogens found in municipal wastewater is the genus Salmonella. The Salmonella group contains a wide variety of species that can cause disease in humans and animals. The most severe form of salmonellosis is typhoid fever, caused by Salmonella typhi. A less common genus of bacteria in wastewater is Shigella, which produces an intestinal disease known as bacillary dysentery or shigellosis. Waterborne outbreaks of shigellosis have been reported where wastewater has contaminated wells used for drinking wiate~6’~

Other bacteria isolated from raw wastewater include Vibrio, Mycobacterium, Clostridium, Leptospira and Yefsinia species. While these pathogens may be present in wastewater, their concentrations are usually too low to initiate disease outbreaks, Vibrio cholerae is the disease agent for cholera, which is not common in the United States but is still prevalent in other parts of the world. Humans are the only known hosts, and the most frequent mode of transmission is through water. Mycobacterium tuberculosis has been found in wastewaiter,‘ and outbreaks have been reported among persons swimming in water contaminated with wastewater.’

Waterborne gastroenteritis of unknown cause is frequently reported, with the suspected agent being bacterial. One potential source of this disease is certain gram-negative bacteria normally considered to be nonpathogenic. These include enteropathogenic Escherichia coli and certain strains of pseudomonas, which may affect the newborn. Waterborne enterotoxigenic E. coli have been implicated in gastrointestinal disease outbreaks.”

Campylobacter coli has been identified as the cause of a form of bacterial diarrhea in humans. While it has been well established that this organism causes disease in animals, it has also been implicated as the etiological agent in human waterborne disease outbreaks.”

Coliform bacteria are commonly used as indicators of fecal contamination and the potential presence of pathogenic species. While coliforms generally respond similarly to environmental conditions and treatment processes as many bacterial pathogens, coliform bacteria determinations by themselves do not adequately predict the presence or concentration of pathogenic viruses or protozoa. Concerns for newly-emerging pathogenic organisms which may arise from nonhuman reservoirs, e.g , Giardia and Cryptosporidium, have led to questioning the use of indicators that arise primarily from human fecal inputs.” The cysts and oocysts responsible for the spread of these organisms are not as readily inactivated by chlonne as bacterial surrogates now in use.

Protozoa

Several pathogenic protozoan parasites have been detected in municipal wastewater. One of the most important of the parasites is the protozoan Entamoeba histolyfica, which is responsible for amoebic dysentery and amoebic hepatitis. The diseases are found worldwide, but in the US., Entamoeba hisfolyfica has not been an important disease agent since the 1950s.

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d

Waterbome disease outbreaks around the world have been linked to the protozoans Giardia lamblia and Cryptosporidium, although no giardiasis or cryptosporidiosis cases related to water reuse projects have been reported. Giardiasis and cryptosporidiosis are emerging as major waterborne diseases. Infection is caused by ingestion of Giardia cysts or Cryptosporidium oocysts. The cysts and oocysts are present in most wastewaters and are more difficult to inactivate by chlonnation than are bacteria and viruses. Cryptosporidiosis can be fatal to immuno-mmpromised individuals.

Helminths

The most important helminthic parasites that may be found in wastewater are intestinal worms, including the stomach worm Ascaris lumbricoides, the tapeworms Taenia saginata and Taenia solium, the whipworm Trichuris trichirar, the hookworms Ancylostoma duodenia and Necator americanus, and the threadworm Strongyloides sterc:oralis. The infective stage of some helminths is either the adult organism or larvae, while the eggs or ova of other helminths constitute the infective stage. The free-living nematode larvae stages are not pathogenic to human beings. The eggs and larvae are resistant to environmental stresses and may survive usual wastewater disinfection procedures, although eggs are readily removed by conimonly used wastewater treatment processes such as sedimentation, filtration, or stabilization ponds.

Viruses

Over 100 differenl types of enteric viruses capable of producing infection or disease are excreted by humans. Enteric viruses multiply in the intestinal tract and are released in the fecal matter of infected persons. Not all types of enteric viruses cause waterbome disease.

The most important human enteric viruses are the enteroviruses (polio, echo, and Coxsackie), Norwalk virus, rotaviruses, reoviruses, parvoviruses, adenoviruses, and hepatitis A viru~.‘~‘‘’ The reoviruses and adenoviruses, which are known to cause respiratory illness, gastroenteritis, and eye infections, have been isolated from wastewater. Of the viruses that cause diarrheal disease, only the Norwalk virus and rotavirus have been shown to be major waterborne pathogens.” There is no evidence that the human immunodeficiency virus (HIV), the pathogen that causes the acquired immunodeficiency syndrome (AIDS), can be transmitted via a waterborne r o ~ t e . ’ ~ ” ~

It has been reported that viruses and other pathogens in wastewater used for crop irrigation do not readily penetrate fruits or vegetables unless the skin is broken.” In one study where soil was inoculated with poliovirus, viruses were detected in the leaves of plants only when the plant roots were damaged or cut.” Although absorption of viruses by plant roots and subsequent acropetal translocation has been reported,” it probably does not occur with sufficient regularity to be a mechanism for the transmission of viruses. Therefore, the likelihood that pathogens would be translocated through trees or vines to the edible part of crops is extremely low.

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Presence and Survival of Pathogens

The occurrence and concentration of pathogenic microlorganisms in raw wastewater depend on a number of factors, and it is not possible to predict with any degree of assurance what the general characteristilcs of a particular wastewater will be with respect to infectious agents. These factors include the sources contributing to the wastewater, the general health of the contributing population, the existence of disease carriers in the populatioii, and the ability of infectious agents to survive outside their hosts under a variety of environmental conditions.

The Occurrence of virus in municipal wastewater fluctuates widely. Virus concentrations are generally highest during the summer and early autumn months. Viruses as a group are generally more resistant to environmental stresses than many of the bacteria, although some viruses persist for oinly a short time in municipal wastewater. The infectious doses of selected pathogens and the concentration ranges of some microorganisms in raw sewage are presented in Tables 3 and 4, respectively.

Under favorable conditions, pathogens can survive for long periods of time on crops or in water or soil. While various pathogens exhibit a wide range of survival characteristics, environmental factors that affect survival include soil organic matter content (presence of organic matter aids survival), temperature (longer survival at low temperatures), humidity (longer survival at high humidity), pH (bacteria survive longer in alkaline soils than in acid soils), amount of rainfall, amount of sunlight (solar radiation is detrimental to survival), protection provided by foliage, and competitive microbial fauna and flora. Survival times for any particular microorganism exhibit wide fluctuations under differing conditiions. Typical ranges of survival times for some common pathogens on crops and in water and soil are presented in Table 5.

At low temperatures (below 4 "C) some microorganisms can survive in the underground for months or years. One study indicated that the die-off rate was approximately doubled with each 10 "C rise in temperature between 5 "C and 30 0C.20 Keswick et a/.'' reported a IO-fold decrease in poliovirus titer every 5 days at groundwater temperatures of 5-13 "C, whereas Jansons et al." found that the same decrease in virus titer required 26 days at groundwater temperatures of 15- 18 "C. In general, increasing cation concentration and decreasing pH and soluble organics tend to promote virus ad~orption.'~

Viruses have been isolated after various migration distances by a number of investigators examining a variety of recharge operations. Bacteria and larger organisms associated with wastewater are effectively removed after percolation through a short distance of the soil mantle.

Aerosols

The concentration of pathogens in aerosols caused by spraying of wastewater is a function of their concentration in the applied wastewater and the aerosolization efficiency of the spray process. During spray irrigation, the amount of water that is aerosolized can vary from less than 0.1 percent to almost two percent, with a mean aerosolization efficiency of one percent or less2'-*' Infection or disease may

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be contracted directly by aerosols deposited on surfaces such as food, vegetation, and clothes. The infective dose of some pathogens is lower for respiratory tract infections than for infections via the gastrointestinal tract; thus, for some pathogens, inhalation may be a more likely route for disease transmission than either contact or ingestion.” A comprehensive review of viruses indicated that a number of waterborne viruses are capable, if aerosolized and subsequently inhaled, of producing respiratory tract infections and disease.”

In general, bacteria and viruses in aerosols remain viable and travel farther with increased wind velocity, increased relative humidity, lower temperature, and lower solar radiation. Other important factors include the initial concentration of pathogens in the wastewater and droplet size. Aerosols can be transmitted for several hundred meters under optimum conditions. Some types of pathogenic organisms, e.g., enteroviruses and Salmonella, appear to survive the wastewater aerosolization process much better than the indicator organisms.3o Bacteria and viruses have been found in aerosols emitted by spray irrigation systems using untreated and poorly treated wastewater.3oJz

Several studies in the U.S. have been directed at residents in communities subjected to aerosols from sewage treatment plant^.'^^^^'^^ These investigations have not detected <any definitive correlation between exposure to aerosols and disease. There have not been any documented disease outbreaks resulting from spray irrigation with disinfected reclaimed water, and studies indicate that the health risk associated with aerosols from spray irrigation sites using reclaimed water is For intermittent spraying of properly disinfected reclaimed water, occasional inadvertent contact should pose little health hazard from inhalation. However, the general practice is to limit exposure to aerosols produced from reclaimed water th,at is not highly disinfected through design or operational controls.

Aerosols originating from industrial cooling towers has also been studied. Although aerosols generated from disinfected wastewater have not been implicated in disease outbreaks, indicate that cooling tower aerosols can include substantial numbers of bacteria. Several regulatory agencies require that reclaimed water used in cooling towers be essentially free of measurable levels of pathogen^.^^.^' This is typically accomplished by secondary treatment followed by filtration and high level disinfection to achieve effluent levels with less than 2.2 total coliform organismsl’l00 mL or no detectable fecal coliform organismsll00 mL.

Disease Incidence Related to Water Reuse

Epidemiological investigations directed at wastewatercontaminated drinking water supplies, the use of raw or minimally treated wastewater for food crop irrigation, health effects on farmworkers who routinely come in contact with poorly treated wastewater used for irrigation, and the health effects of aerosols or windblown spray emanating from spray irrigation sites using undisinfected wastewater have all provided evidencle of infectious disease transmission from such practices.4o43

In one survey of 6:3 disease outbreaks (some dating back to the late 1800s) associated with foods contaminated by sewage sludge or wastewater, vegetables contaminated by raw or partially treated sewage were implicated as the vehicle in

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12 outbreaks, and watercress in 10 outbreaks. Some were due to contamination by animal feces, and fruit was the vehicle in four of the reported outbreak^.'^

Excluding the use of raw sewage or primary effluent on sewalge farms in the late 19th century, there have not been any reported cases of intestinal diseases in connection with reuse projects in the US. In developing countries, on the other hand, the irrigation of market crops with poorly-treated wastewater is a major source of enteric disease.

Although pathogen-free water is not needed for all reclaimed1 water applications, the general practice is to provide water of a quality appropriate for the highest nonpotable use in a community. Since the highest level uses (e.g., residential landscape irrigation, toilet flushing, and the irrigation of parks) require essentially pathogen-free water, in most cases all reclaimed water distributed throughout a community meets this requirement. Wastewater treated to this level would not present risks of infectious disease from infrequent, inadvertent

Water Quality Considerations: Chemical Constituents

The chemical constituents potentially present in municipal wastewater generally are not a major health concern for urban uses of reclaimed water but may affect the acceptability of the water for uses such as food crop irrigation and industrial applications. With the exception of the possible inhalation of volatile organic compounds from indoor exposure, there are minimal health concerns associated with chemical constituents where reclaimed water is not intended to be consumed. Chemical constituents may be of concern when reclaimed water percolates into potable groundwater aquifers as a result of irrigation, groundwater recharge, or other uses. Some inorganic and organic constituents and their potential significance in water reclamation and reuse have been summarized by other^^,^' and are discussed below.

Biodegradable Organics: Biodegradable organics can create aesthetic and nuisance problems. Organics provide food for microorganics, adversely affect disinfection processes, make water unsuitable for somie industrial or other uses, consume oxygen, and may cause acute or chronic: effects if reclaimed water is used for potable purposes.

Nutrients: Nitrogen, phosphorus, and potassium are essential nutrients for plant growth, and their presence normally enhances the value of the water for irrigation. When discharged to the aquatic environiment, nitrogen and phosphorus can lead to the growth of undesirable aquatiic life. When applied at excessive levels on land, the nitrate form of nitrogen will readily leach through the soil and may cause groundwater concentrations to exceed drinking water standards.

9 Stable Organics: Some organic constituents tend to resist conventional methods of wastewater treatment. Some organic compaunds are toxic in the environment, and their presence may limit the suitability of reclaimed water for irrigation or other uses.

Hydrogen Ion Concentration: The pH of wastewater affects disinfection efficency, coagulation, metal solubility, as well as alkalinity of soils. Normal

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pH range in miunicipal wastewater is 6.5 - 8.5, but industrial wastes may have pH characteristics well outside of this range.

Heavy Metals: Some heavy metals accumulate in the environment and are toxic to plants and animals. Their presence in reclaimed water may limit the suitability of the water for irrigation or other purposes.

Dissolved Inorganics: Excessive salinity may damage some crops. Specific ions such as chloride, sodium, and boron are particularly toxic to some crops. Sodium may pose soil permeability problems.

Residual Chlorine: Excessive amounts of free available chlorine p0.05 mg/L) may cause leaf-tip bum and damage some sensitive crops. However, most chlorine in reclaimed water is in a combined form, which does not cause crop damage. Some concerns are expressed as to the toxic effects of chlorinated organics in regard to contamination of potable underground aquifers.

Suspended Solids: Organic contaminates, heavy metals, etc. are adsorbed on particulates. Suspended matter can shield microorganisms from disinfectants. Suspended solids can lead to sludge deposits and anaerobic conditions if discharged to the aquatic environment. Excessive amounts of solids cause clogging in irrigation systems.

The concentrations of inorganic constituents in reclaimed water depend mainly on the nature of the water supply, source of wastewater, and degree of treatment provided. Residential use of water typically adds about 300 mglL of dissolved inorganic solids, although the amount added can range from approximately 150 mg/L to more than 500 mg/L.48 The presence of total dissolved solids, nitrogen, phosphorus, heavy metals, and other inorganic constituents may affect the suitability of reclaimed water for different reuse applications. Wastewater treatment generally can reduce many trace elements to below recommended maximum levels for irrigation and other nonpotable uses with existing technol~gy.'~

Organic constituents impose a number of potential adverse effects on nonpotable uses of reclaimed water:

Aesthetically displeasing: they may be malodorous and impart color to the water.

Nuisance: dleposits of organic matter may present vector and related health problems.

Clogging: piarticulate matter may clog sprinkler heads or accumulate in soil and affect permeability.

Oxygen consuming: organic substances, upon decomposition, deplete the dissolved oxygen content in streams and lakes, thus negatively impacting aquatic life which depends on this supply of oxygen for survival.

Use-limiting: many industrial applications cannot tolerate water high in organic content.

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Disinfection effects: organic matter can interfere with chlorine, ozone, and ultraviolet disinfection, making them less available for disinfection purposes. Also, the reaction of disinfectants with organiics in water creates a wide range of byproducts that are perceived as hannful to health when ingested.

Health effects: certain synthetic organic compounds may cause acute or chronic health effects when ingested or inhaled.

The health effects related to the presence of organic constituents are of primary concem with regard to potable reuse, and both organic and inorganic constituents need to be considered where reclaimed water is utilized for food crop irrigation, where reclaimed water from irrigation or other beneficial uses reaches potable groundwater supplies, or where the organics may bioaccumulale in the food chain, e.g., in fish rearing ponds.

In addition, where chlorine is used for disinfection purposes, organic compounds in wastewater can be transformed into chlorinated organic species. In the treatment of reclaimed water for nonpotable applications, the use of larger dosages of chlorine than are customarily used for potable water is appropriate because ingestion of disinfection byproducts is not at issue. Similaily, the presence of synthetic organic chemicals in reclaimed water is of little concem in many nonpotable applications. However, when such waters are sprayed, whether for irrigation, in industrial processes, or in omamental fountains, the release of volatile organic compounds (VOCs) may be a problem.

lrriqation

Guidelines developed by Ayers and Westcot5' and a University of Califomia Committee of Consultants5' for evaluating irrigation water quality are summarized in Table 6. Table 7 shows EPA's recommended limits for healvy metals, pH, TDS, and free chlorine residual in irrigation water. The recornmended maximum concentrations for long-term continuous use, i.e., more than 20 years, on all soils are set conservatively, to include sandy soils that have low capacity to leach the element in question. These maxima are below the concentrations that produce toxicity when the most sensitive plants are grown in nutrieint solutions or sand cultures to which the pollutant has been added. Repeated applications in excess of suggested levels might induce phytotoxicity. The criteria for short-term use, i.e., up to 20 years, are recommended for fine-textured neutral and alkaline soils with high capacities to remove the different pollutant elements.'

Free chlorine residual at concentrations less than 1 mglL usually poses no problem to plants5 However, some sensitive crops may be damaged at levels as low as 0.05 mglL. Some woody crops may accumulate chlorine in the tissue to toxic levels. Excessive chlorine has a similar leaf-buming effect as sodium and chloride when sprayed directly on foliage. Chlorine at concentrations greater than 5 mglL causes severe damage to most plants.

Both the concentration and form of nitrogen need to be considered in irrigation water. While excessive nitrogen stimulates vegetative growth in most crops, it may also delay maturity and reduce crop quality and quantity. In addition, excessive nitrate in forages can cause an imbalance of nitrogen, potassium, and magnesium

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in the grazing animals and is a concem if the forage is used as a primary feed source for livestock; however, such high concentrations are usually not expected with municipal reclaimed water. The addition of potassium with reclaimed water has little effect on the crop. Excessive phosphorus does not appear to pose any problem to crops, but can be a problem in runoff to surface waters.

Aside from public hiealth concerns associated with reclaimed water reuse, salinity is one of the most important parameters in determining the suitability of water for irrigation.' For example, salinity may influence the soil's osmotic potential, specific ion toxicity, and degradation of soil physical conditions. These conditions may result in reduced plant growth rates, reduced yields, and, in severe cases, total crop failure. Highly saline water applied via overhead sprinklers results in direct absorption of sodium andlor chloride and can cause leaf injury, particularly during periods of high temperature and low humidity.

Trace elements in reclaimed water normally occur in concentrations of less than a few mg/L, with u!jual concentrations less than 100 P~/L .~ ' Some are essential for plants and animals, but all can become toxic at elevated concentrations or

The mec:hanisms of potential food contamination from irrigation with reclaimed water include: physical contamination, where evaporation and repeated application may result in a build-up of contaminates on crops; uptake through the roots from the aplplied water or the soil; and foliar intake. Some chemical constituents are known to accumulate in particular crops, thus presenting health hazards to both grauing animals and/or humans.

The elements of greatest concern at elevated levels are cadmium, copper, molybdenum, nickel, and zinc. Nickel and zinc are a lesser concem than cadmium, copper, and molybdenum because they have visible adverse effects in plants at lower concentrationls than the levels harmful to animals and humans. Zinc and nickel toxicity decrease as pH increases. Cadmium, copper, and molybdenum, however, can be harmful to animals at concentrations too low to affect plants.

Copper is not toxic to monogastric animals, but may be toxic to ruminants; however, their tolerance to copper increases as available molybdenum increases.' Molybdenum can also be toxic when available in the absence of copper. Cadmium is of particular concern because it can accumulate in the food chain. It does not adversely affect rurninants in the small amounts they ingest. Most milk and beef products are also unaffected by livestock ingestion of cadmium because it is stored in the liver and kidneys of the animal rather than the fat or muscle tissues.

A study in California evaluated the concentration of heavy metals in agricultural plots irrigated with reclaimed water and well ~ a t e r . ~ ' After a five-year period, concentrations in thle soils did not increase, except for copper, which rose for all water types, yet still was below the average of California soils. It was determined that concentrations were so low (below detection for the most part), that irrigation for much longer peiiods would lead to the same conclusion as the five-year test with the exception e4 iron and zinc (two essential plant and animal micronutrients). It was found that iron was more concentrated in plots irrigated with well water and zinc was greater with the reclaimed water. However, at the levels found for either, the uptake by plants would be greater than the accumulation from irrigation input. In addition, it was found that the input of heavy metals from mmmercial chemical fertilizer impurities was far greater than that contributed by the reclaimed water.

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While a considerable amount of information is available regardiing the assessment of microorganisms, heavy metals, and other inorganic constituents in irrigation water, less attention has been given to potential health effects associated with many organic chemicals. The existing research does not indicate that organic constituents in reclaimed water accumulate to hazardous levids in food crops or that they contaminate groundwater.

Crop uptake of certain pesticides has been and uptake of polychlorinated biphenyls by root crops has been demonstrated under field condition^.^^ Uptake of organic compounds is affected by: the solubility, size, concentration, and polarity of the organic molecules; the organic content, pH, and microbial activity of the soil; and the climate. A study of health risks associated with land application of sludge found that not more than 3 percent of the pesticides and herbicides present in the soil passed into plant f~l iage.~’ It has been postulated that most trace organic compounds are too large to pass through the semipermeable membrane of plant roots.’

When reclaimed water is used in a drip system, filtration may be needed to prevent complete or partial clogging of emitters, and close, regular inspections of emitters are needed to detect emitter clogging. In-line 80- to 200-mesh filters are typically used to minimize clogging,‘ although Lau and Wu5’ reported that 60- to 120-mesh screens were successfully used during tests performed to evaluate the plugging of 0.75 mm emitters using prmary and secondaiy treated domestic wastewater. In addition to clogging, biological growth within thie transmission lines and at the emitter discharge may be stimulated by nutrients in the reclaimed water. Due to low volume application rates with micrc-irrigation, salts may accumulate at the wetted perimeter of the plants and then be released at toxic levels to the crop when leached via rainfall.

Numerous site-specific studies have been conducted regarding the potential water quality concems of irrigation with reclaimed water. A survey of agricultural systems operating in Califomia found no indications that crop quality or quantity had deteriorated as a result of using reclaimed water for irrigati~in.~’ A Florida study of citrus irrigation with highly disinfected, filtered, secondary effluent indicated that the use of reclaimed water had no detrimental effects on crop production, soil, or groundwater.60 These and other investigations6’ suggest that reclaimed water will be suitable for most agricultural irrigation needs.

Reclaimed water that meets recommended water quality liimits for agricultural irrigation water is generally acceptable for irrigation of turf arid ornamental plants and shrubs. However, extensive studies in St. Petersburg, Florida determined that chloride levels above 400 mglL in irrigation water for an e~ended time period damaged salt-sensitive species of plant^.^^^^^ The studies indicated that three species of plants, Le., crape myrtle, azaleas, and Chinese privet, have extremely low salt tolerances and should not be irrigated with reclaimed water. In California, the Goleta Sanitary District has included reverse osmosis as one of the reclaimed water treatment processes to lower the chloride content of the irrigation water to less than 300 mg/L for the protection of golf course greens and sensitive plants.64

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Industrial Reuse

Typical industrial uses for reclaimed water are listed in Table 1. Some of the principal concems regarding the use of reclaimed water in industrial applications are discussed below.

Cooling Water

A major health concern associated with industrial reuse is pathogens in the water that may pose hazards to workers and to the public in the vicinity of cooling towers. Aerosols produced in the workplace or from cooling towers also may present hazards from the inhalation of volatile organic chemicals, although little definitive research has been done in this area. Closed-loop cooling systems using reclaimed water present minimal health concerns unless there is inadvertant or intentional misuse of the water.

The most common (operational problems with cooling water systems are scaling, corrosion, biological growth, fouling, and foaming. These disorders are caused by contaminants in potable water as well as reclaimed water, but the concentrations of some contaminarits in reclaimed water may be higher. Table 8 lists suggested water quality criteria for cooling water supplies.

Cooling water should not lead to the formation of scale, Le. hard deposits in the cooling system. Such deposits reduce the efficiency of the heat exchange. The principal causes of scaling are calcium (as carbonate, sulfate, and phosphate) and magnesium (as cartmate and phosphate) deposits. Scale control for reclaimed water is achieved through chemical means and sedimentation. Acidification or addition of scale inhibitors can control scaling. Acids (sulfuric, hydrochloric, and citric acids and acid gases such as carbon dioxide and sulfur dioxide) and other chemicals (chelants such as EDTA and polymeric inorganic phosphates) are often added to increase the water solubility of scale-forming constituents, such as calcium and magne~ ium.~~ Lime softening removes carbonate hardness and soda ash removes noncarbonate hardness. Other methods used to control scaling are alum treatment and sodium ion exchange.

High levels of dissolved solids, ammonia, and heavy metals in reclaimed water can cause serious increased corrosion rates.= The concentrations of TDS in municipally treated reclaimed water can increase electrical conductivity and promote corrosion. Ammonia is very aggressive to copper alloys. Dissolved gases and certain metals with high oxidation states also promote corrosion. For example, heavy metals, particularly copper, can plate out on mild steel, causing severe pitting. Corrosion may also occur when acidic conditions develop in the cooling water.

Corrosion inhibitors such as chromates, polyphosphates, zinc, and polysilicates can be used to reduce the corrosion potential of the cooling water. These substances may have to be removed from the blowdown prior to discharge. The alternative to chemical addition is ion exchange or reverse osmosis.65

Reclaimed water used in cooling systems should not supply nutrients or organic matter that promote the growth of slime-forming organisms. The moist environment in the cooling tower is conducive to biological growth. Microorganisms can

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significantly reduce the heat transfer efficiency, reduce water flow, and in some cases generate corrosive by-products.6769

Sulfide-producing bacteria and sulfate-reducing bacteria are the most common corrosioncausing organisms in cooling systems using reclaimed water." These anaerobic sulfide producers occur beneath deposits and cause pitting corrosion that is most severe on mild and stainless steels. Serious corrosion is caused by thiobaccillus bacteria, an acid-producer that converts sulfidles to sulfuric acid. Similarly, nitrifying bacteria can convert ammonia to nitric acid, thus causing pH depression, which increases corrosion on most metals."

Removal of BOD and nutrients during treatment reduces the potential of the reclaimed water to sustain microorganisms. Chlorine is the most common biocide used to control biological growth because of its low cost, availability, and ease of operation. Chlorination is also used as a disinfectant to reduce potential pathogens in the reclaimed water. Frequent chlorination and shock treatment are generally adequate.

Non-oxidizing microbiccides are generally required in addition to chlorine because of the high nutrient content typically found in wastewater. Since most scale inhibitors and dispersants are anionic, either anionic or nonionic biocides are usually used. Low-foaming, nonionic surfactants enhance microbiological control by allowing the microbiocides to penetrate the biological

Fouling is controlled by preventing the formation and settling d particulate matter. Chemical coagulation and filtration during the phosphorus removal treatment phase significantly reduce the contaminants that can lead tal fouling. Chemical dispersants are also used as required.

Boiler-Feed Water

The use of reclaimed water differs little from the use of conventional public supplies for boiler-feed water; both usually require extensive additional treatment. Quality requirements for boiler-feed makeup water are also dependent upon the pressure at which the boiler is operated, as shown in Table 9. Generally, the higher the pressure, the higher the quality of water required. Very high pressure boilers require makeup water of distilled quality.70 High alkalinity may contribute to foaming, resulting in deposits in the superheater, reheater, and turbines. Bicarbonate alkalinity, under the influence of boiler heat, may lead to the release of carbon dioxide, which is a source of corrosion in steam-using equipment.

In general, both potable water and reclaimed water used for high-pressure boiler water must be treated to reduce the hardness to nearly zero. Removal or control of insoluble salts of calcium and magnesium and control of silica and aluminum are required, since these are the principal causes of scale build-up in boilers. Depending on the characteristics of the reclaimed water, lime! treatment (including flocculation, sedimentation, and recarbonation) might be required, possibly followed by multi-media filtration, carbon adsorption, and nitrogen removal. High-purity boiler-feed water for high-pressure boilers might also require treatment by reverse osmosis or ion e~change.~' The considerable treatment and the relatively small amounts of makeup required make boiler-feed a poor candidate For reclaimed water.

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Industrial Process Water

The suitability of reclaimed water for use in industrial processes depends on the particular use. For example, the electronics industry requires water of almost distilled quality for washing circuit boards and other electronic components. On the other hand, the tanning industry can use relatively low-quality water. Requirements for textiles, pulp arid paper, and metal fabricating are intermediate. Table 10 presents industrial process water quality requirements for a variety of industries.

Use of reclaimed water in the paper and pulp industry is a function of the grade of paper produced. The higher the quality of the paper, the more sensitive it is to water quality. Impurities found in water, particularly certain metal ions and color bodies, can cause the paper to change color with age. Biological growth can cause clogging of equipment and odors and can affect the texture and uniformity of the paper. Corrosion and scaling of equipment may result from the presence of silica, aluminum, and hardness. Discoloration of paper may occur due to iron, manganese, or micro-organisms. Suspended solids may decrease the brightness of the paper.72

Water used in textilie manufacturing must be nonstaining; hence, it should be low in turbidity, color, iron, and manganese. Hardness causes curds to deposit on the textiles and causes problems in some of the processes that use soap. Nitrates and nitrites may cause problems in dyeing.

Groundwater RechEm

The purposes of groundwater recharge using reclaimed water include establishing saltwater intrusion barriers in coastal aquifers, providing further soil-aquifer treatment (SAT) for future reuse, providing storage of reclaimed water, controlling or preventing grounld subsidence, and augmenting potable or nonpotable aquifers.

Primary effluent has been successfully used in soil-aquifer treatment systems at some spreading sites where the extracted water is to be used for nonpotable purpose^.^^-^^ The higher organic content of primary effluent may enhance nitrogen removal by denitrification in the SAT system7' and may enhance removal of synthetic organic: compounds by stimulating greater microbiological activity in the A disadvantage of using primary effluent is that infiltration basin hydraulic loading rates may be lower. In most cases wastewater receives at least secondary treatment and disinfection, and often tertiary treatment by filtration, prior to surface spreading.

Algae can clog the soil surface of spreading basins and reduce infiltration rates. Algae further aggravate soil clogging by removing carbon dioxide, which raises the pH, causing precipitation of calcium carbonate. Reducing the detention time of the standing water within the basins minimizes algal growth. linfiltration basins should be shallow enough to avoid compaction of the clogging layer.77 Also, scarifying, rototilling or discing the soil following the drying cycle can help alleviate clogging potential, although scraping or "shaving" the bottom to remove the clogging layer is more effective than discing it.

Contaminants in thle subsurface environment are subject to processes such as biodegradation by microorganisms, adsorption, filtration, ion exchange,

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volatilization, dilution, chemical oxidation and reduction, and chemical precipitation and complex formation.78379 For surface spreading operations, most of the removals of both chemical and microbiological constituents i m u r in the top 2 m (6 feet) of the vadose zone at the spreading site.

Particles larger than the soil pores are strained off at the soil-water interface. Particulate matter, including some bacteria, is removed by sedimentation in the pore spaces of the media during filtration. Viruses are removed mainly by adsorption. The accumulated particles gradually form a layer restricting further infiltration. Suspended solids that are not retained at the soil-water interface may be effectively removed by infiltration and adsorption in the !soil profile. As water flows through passages formed by the soil particles, suspended and colloidal solids too small to be retained by straining are intercepted arid adsorbed onto the surface of the stationary soil matrix through hydrodynamiic actions, diffusion, impingment, and sedimentation.

Some inorganic constituents such as chloride, sodium, and sulfate are unaffected by ground passage, but there can be substantial removal of imany other inorganic constituents. For example, iron and phosphorus removals in excess of 90 percent have been achieved by precipitation and adsorption in ithe underground,''.'' although the ability of the soil to remove these and other constituents may decrease over time. On the other hand, one study found that injection of reclaimed water having a dissolved oxygen concentration of 4.5 mg/L resulted in a 3 mglL increase in the iron concentration." Heavy metal removal varies widely for the different elements, ranging from 0 to more than 90 piercent, depending on speciation of the influent metals.

Some trace metals (e.g., silver, chromium, fluoride, molybdenum, and selenium) are strongly retained by There are indications that once metals are adsorbed, they are not readily desorbed, although desorptiori depends, in part, on buffer capacity, salt concentrations, and reduction-oxidatioil potential." Boron, which is mainly in the form of undissociated boric acid in soil solutions, is rather weakly adsorbed and, given sufficient amounts of leaching water, most of the adsorbed boron is de~orbed.'~

For surface spreading operations where an aerobic zone is maintained, ammonia is effectively converted to nitrates, but subsequent denitrification is dependent, in part, on anaerobic conditions during the flooding cycle and is often partial and fluctuating unless the system is carefully managed.

Adsorption of organic constituents retards their movement (they can desorb and move chromatographically in the underground) and attenuates concentration fluctuations. The degree of attenuation increases with increasing adsorption strength, increasing distance from the recharge point, and increasing frequency of input fl~ctuation.~' Recharged water may be free of many chemicals when it first appears at an extraction well, but the chemicals may begin to appear much later. Thus, chemical retardation needs to be evaluated when determining the effectiveness of contaminant removal in a recharge system."6

Direct injection involves pumping reclaimed water directly into the groundwater zone, which is usually a confined aquifer. Injection into a saline aquifer can create a freshwater "bubble," from which water can be extracted for reuse. Direct

44

injection is also an effective method for creating barriers against saltwater intrusion in coastal areas.

Injection requires water of higher quality than surface spreading to prevent clogging because of the absence of soil matrix treatment afforded by surface spreading, and the potential requirement to match or exceed the quality of the groundwater supply. Treatment processes beyond secondary treatment that may be used prior to injection include disinfection, filtration, air stripping, ion exchange, granular activated carbon, and reverse osmosis or other membrane separation processes. With various subsets of these processes in appropriate combinations, it is possible to sati:sfy the full range of water quality requirements for injection.

Clogging of injection wells can be caused by accumulation of organic and inorganic solids, biological and chemical contaminants, and dissolved air and gases from turbulence. Concentrations of suspended solids of 1 mglL or greater can clog an injection well. Low concentrations of organic contaminants can cause clogging due to bacteriological growth near the point of inje~tion.~’

Recreational and Environmental Uses

These uses of reclaiimed water include impoundments, which provide recreational benefits, as well as enhancements to the environment such as wetlands and stream augmentation. Often, the primary intent in applying reclaimed water to wetlands is to provide additional treatment of effluent prior to discharge, although wetlands are sometimes created solely for environmental enhancement (e.g., wildlife habitat), and the use of treated wastewater may be ideal for this purpose.

Appropriate plant species are selected based on the quality and quantity of reclaimed water applied to the wetland system. A salinity evaluation on any created wetlands is; important, since highly saline wetlands often exhibit limited vegetative growth, although saline wastewaters may be particularly valuable for marine wetlands. Protection of groundwater quality is also an important consideration.

A number of states have regulations which specifically address the use of reclaimed water in wetlands systems. Where specific regulations are absent, wetlands have been constructed on a case-by-case basis. In addition to state requirements, natuKal wetlands, which are considered waters of the United States, are protected under EPA’s NPDES Permit and Water Quality Standards programs. Constructed wetlands, on the other hand, which are built and operated for the purpose of wastewater treatment, are generally not considered waters of the United States.88

Impoundments may serve a variety of functions from aesthetic, non-contact uses, to boating, fishing, and swimming. As with other uses of reclaimed water, the level of treatment required will vary with the intended use of the water. As the potential for human contacit increases, the required treatment levels increase. The appearance of the fieclaimed water is important when it is used for impoundments, and treatment for nutrient removal may be required. Without nutrient control there is a high potential fior algae blooms, resulting in odors, an unsightly appearance, and eutrophic conditions.

45

Stream augmentation is different from surface water discharge in that augmentation seeks to accomplish a beneficial end, whereas surface discharge is a disposal alternative. As with impoundments, the water quality requirements for stream augmentation are based upon the designated use of the stream and maintenance of required water quality standards. In addition, there may be an emphasis on creating a product that improves existing stream quality to sustain or enhance aquatic life. To achieve aesthetic goals, both nutrient removal and high- level disinfection are often needed. Dechlorination may be required to protect aquatic wildlife where chlorine is used as the wastewater disinfectant.

Water Reclamation and Reuse Criteria

There are no federal regulations goveming water reclamatioin and reuse in the U.S.; hence, the regulatory burden rests with the individual states. Prior to release of the Guidelines for Water Reuse,' a document jointly sponsored by EPA and the U.S. Agency for lntemational Development, states received llittle guidance from federal agencies for criteria development. This has resulted in widely differing standards among states that have developed reuse criteria.

No states have regulations that cover all potential uses of reclaimed water, but several states have extensive regulations or guidelines that prescribe requirements for a wide range of uses. Other states have regulations or guidelines that focus on land treatment of wastewater effluent, emphasizing additional treatment or effluent disposal rather than beneficial reuse, even though the effluent may be used for irrigation of agricultural sites, golf courses, or public access lands. In 1992, 18 states had some form of water reuse regulations, 18 states had guidelines, and 14 states had neither regulations nor guidelines.'

The acceptability of reclaimed water for any particular use i!: dependent on the physical, chemical, and microbiological quality of the water. Factors that affect the quality of reclaimed water include source water quality, wastewater treatment processes and treatment effectiveness, treatment reliability, and distribution system design and operation. Industrial source control programs ciin limit the input of chemical constituents that may adversely affect biological treatment processes and subsequent acceptability of the treated wastewater for specific uses. Assurance of treatment reliability is an obvious, yet sometimes overlooked, quality control measure. Distribution system design and operation is important to assure that the reclaimed water is not degraded prior to use and not subject to misuse. Open storage may result in water quality degradation by microorganisms, algae, or particulate matter, and may cause objectionable odor or color in the reclaimed water.

Water quality criteria for nonpotable reuse are based on a variety of considerations:

Public health protection: Reclaimed water should be safe for the intended use. Most existing reclaimed water regulations are principally directed at public health protection, and many address only microbiological concems.

Use requirements: Many industrial uses and some other applications have specific physical and chemical water quality requirements that are not related to health considerations. The physical, chemical, and

46

microbiological quality may all limit the acceptability of reclaimed water for specific USEK

Irrigation elfects: The effect of individual constituents or parameters on crops or otlher vegetation, soil, and groundwater or other receiving water should be evaluated for potential reclaimed water irrigation applications.

Environmental considerations: The natural flora and fauna in and around reclaimed water use areas and receiving waters should not be adversely impacted by the reclaimed water.

Aesthetics: For high level uses, e.g., urban irrigation and toilet flushing, the reclaimed water should be no different in appearance than potable water, Le., clear, colorless, and odorless. For recreational impoundments, reclaimed water should not promote algal growth.

Public andlor user perception: The water should be perceived as being safe and acceptable for the intended use. This could result in the imposition (of conservative reclaimed water quality limits by regulatory agencies.

Political realities: Regulatory decisions regarding water reuse are sometimes based on the political climate, perceived public policy, and cost.

States which have water reuse regulations or guidelines typically have set standards for reclaimed water quality and/or specified minimum treatment requirements. The most common parameters for which water quality limits are imposed are biochiemical oxygen demand (BOD), turbidity or total suspended solids (TSS), total or fecal coliform bacteria, nitrogen, and chlorine residual and contact time.

Where reclaimed water is used in an urban setting, most states require a high degree of treatment and disinfection . Where there is likely to be public contact with the reclaimed water, tertiary treatment to produce finished water that is essentially pathogen-free is typically r e q ~ i r e d . ~ ~ * ~ ~ ~ ~ ~ EPAs Guidelines for Wafer Reuse recommends similar treatment and quality for reclaimed water use in urban areas.

Reclaimed water used inside buildings for toilet and urinal flushing or for fire protection presents crossconnection control concems. Although such uses do not result in frequent human contact with the water, regulatory agencies usually require that the reclaimed water be pathogen-free to reduce health hazards upon inadvertant crossamnection to potable water s y ~ t e m s . ~ ~ ’ ~ ~ . ~ ’

While the need to maintain a chlorine residual in reclaimed water distribution systems to prevent odors, slimes, and bacterial regrowth was recognized early in the development of dual water systems,” only recently have regulatory agencies begun to require such residuals. In Washington, for example, criteria require maintenance of a chlorine residual in distribution systems carrying reclaimed water.93 The Guidelines for Water Reuse recommend that a chlorine residual of at least 0.5 mg/L be maintained in reclaimed water distribution lines.

47

Several states with active reuse programs, e.g., Arizona, Califomia, Florida, and Texas, have comprehensive regulations and prescribe requirements according to the end use of the water. There are differences amonmg 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 thie four states that requires monitoring 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 Arizona and Texas do nck specify treatment processes, although Arizona is considering the inclusion of treatment process requirements in the state’s reuse regulation^;^' and Arizona and Califomia permit the use of reclaimed water for spray irrigation of food crops eaten raw, while such use is prohibited in Florida and Texas.

Arizona

Arizona’s water reuse criteria include limits for viruses and parasites.” For example, the current Arizona reuse standards for the irrigation of food to be consumed raw require that the fecal coliform level not exceed a geometric mean (five sample minimum) of 2.2/100 ml, the turbidity not exceed ’I NTU, the number of enteric viruses not exceed 1 pfu/4OL, and that there be no detectable Entamoeba histolytica, Giardia lamblia, or Ascaris lumbricoides. The Arizona regulations are currently under revision, and indications are that the virus and parasite monitoring requirements will be dropped from the regulations.’‘ The latest draft revisions to the Arizona regulations are based on, and arie similar to, criteria recommended in the Guidelines for Water Reuse.

Califomia

The State of California has a long history of reuse, having developed the first reuse regulations in 1918. These have been modified and expanded through the years. The state’s current Wastewater Reclamation Criteria,” which are in the process of being revised, were adopted in 1978 and have senred as the basis for reuse standards in other states and countries. The reclamation criteria include water quality standards, treatment process requirements, operational requirements, and treatment reliability requirements. The treatment and quality criteria are shown in Table 11. Coliform samples must be collected at least daily and compliance is based on a running seven-day median number. Turbidity and chlorine residual must be monitored continuously.

The coliform levels in Table 11 are not definitive threshold levels justified by rigorous documentation and evaluation of illness rates. At the time the regulations were developed, the Califomia Department of Health Services (DOHS) concluded that epidemiological studies of the exposed population at water reuse sites would be of limited value, and that it was not possible to ascribe numi?rical risk estimates to reclaimed water with any degree of confidence. Thus, the reclamation criteria were based on the capability of well-designed and operated wastewater treatment plants to consistently attain specific reclaimed water quality limits, experience at existing wastewater disposal and reuse operations, evaluation of pertinent research studies and health-related data, and the desire to not allow unreasonable risks due to the use of reclaimed water.

As indicated in Table 11, the required degree of treatment and microbiological quality increase EIS the likelihood of human exposure to the reclaimed water increases. If intimate direct contact with the reclaimed water is expected, such as swimming, or indinect contact is likely, such as consuming produce spray-irrigated with reclaimed water, the regulations specify treatment and water quality requirements intended to produce an effluent that is essentially free of measurable levels of pathogens, including viruses. A fundamental decision was made that the standard to be applied was to be the absence of measurable levels of enterovirus, based on the assumptions that very low numbers of virus can initiate infection and wastewater treatment processes assuredly controlling enterovirus would produce reclaimed water free from any human pathogen and thus be safe for the intended uses.

Selection of the treatment chain specified in the Wastewater Reclamation Criteria to produce an essentially pathogen-free effluent, Le., oxidation, chemical coagulation, clarification, filtration, and disinfection to a total coliform level not exceeding 2.21100 mL, was predicated on studies conducted several years ago to determine the virus removal capability of advanced wastewater treatment processes. More recent s tud ie~~ '~~ ' have found that equivalent virus removal can be achieved by direct filtration of high quality secondary effluent, using low coagulant andlor polymer dosages when necessary to meet the turbidity requirement of 2 hlTU prior to disinfection. This abbreviated treatment chain, in conjunction with specific design and operational controls, e.g., a maximum filtration rate of 12 mlh (5 gpm/ft2) and a theoretical chlorine contact time of at least 2 hours with an actual modal contact time of at least 90 minutes, has been judged to be equivalent to the full treatment chain specified in the regulation^.^^

The Wastewater Reclamation Criteria also include requirements for treatment reliability. The reliability requirements address standby power supplies, alarm systems, multiple or standby treatment process units, emergency storage or disposal of inadeqluately treated wastewater, elimination of treatment process bypass, monitoring devices and automatic controllers, and flexibility of design.

California's reclamation criteria are currently being revised. Likely revisions include the identification of several additional types of reclaimed water applications, e.g., toilet flushing in cornmercial buildings, industrial cooling and process water, single- family residential landscape irrigation, and groundwater recharge by either spreading or injection. Other probable changes include allowance of UV radiation as an altemative to chlorine for uses requiring reclaimed water to be essentially free of measurable levels of pathogen^,'^ a requirement to periodically monitor for viruses in nonrestricted recreational impoundment^,^' and use area controls that currently are guidelines.

Florida

Until recently, the primary driving force behind implementation of reuse projects in Florida was effluent Regulations developed in the early 1980s for reuse and land application were contained in a document entitled Land Application of Domestic Wasfeuwafer Effluent in Norida." Irrigation of public access areas and irrigation of edible crops were allowed but requirements for such activities were incomplete. Rule 17-610, Florida Administrative Code, "Reuse of Reclaimed Water and Land Applicatiion", was adopted in 1989 and revised in 1990. These

49

regulations focus on the beneficial uses of reclaimed water. ‘The treatment and quality criteria are shown in Table 12.

As indicated in Table 12, Florida uses suspended solids as a monitoring tool for filtration effectiveness. In addition, the reuse rule specifies development of an operating protocol whereby’ continuous monitoring of turbidity prior to disinfection and chlorine residual after chlorine contact is required. Flonida does not allow direct contact between reclaimed water and food crops to be eaten raw, although there are provisions to allow this type of reuse based on demonstration studies acceptable to the state.

T B

Texas has adopted regulations that do not specify wastewater treatment processes. In addition, the coliform requirements specified in the Texas regulations are considerably more lenient than in many of the other states that have developed comprehensive water reclamation and reuse criteria. The Texas water quality criteria are summarized in Table 13.

The Texas water reclamation requirements” for toilet flushing water and irrigation of unrestricted landscaped areas specify a maximum fecal coliform level of 75/100 mL and a maximum BOD of 5 mg/L. This BOD limitation is more restrictive than that in any other state for these types of reuse. Weekly monitoring for BOD and coliform concentrations is required where reclaimed water is used for food crop irrigation, unrestricted landscape irrigation, impoundment, <and toilet flushing. Reclaimed water used to irrigate pasture for milking animals must be sampled every two weeks. Food crops which may be consumed raw by humans cannot be spray irrigated with reclaimed water. If irrigation water is stored prior to application, provision must be made to provide additional disinfection to meet the specified criteria for the designated area.

EPA Guidelines

In recognition of the increasing role of water reuse as an integral component of the nation’s water resources management and the wide variance of state reuse criteria, EPA, in conjunction with the US. Agency for International Development, published Guidelines for Wafer Reuse in 1992. The primary purpose of the document is to provide 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 guidelines primiarily address water reclamation and reuse for nonpotable urban, industrial, and agricultural applications, although attention is also given to augmentation of potable supplies by indirect reuse.

The guidelines address all important aspects of water reuse, including recommended treatment processes, reclaimed water quality limits, monitoring frequencies, setback distances, and other controls for various reuse applications. The treatment processes and reclaimed water quality limits recommended in the guidelines for various reclaimed water applications are presented in Table 14.

Both wastewater treatment and reclaimed water quality limits are recommended, for the following reasons: water quality criteria involving surrogate parameters do

50

not adequately characterize reclaimed water quality; a combination of treatment and quality requirernents known to produce reclaimed water of acceptable quality obviate the need to monitor the finished water for certain constituents; expensive, timeconsuming, aind in some cases, questionable monitoring for pathogenic microorganisms is eliminated without compromising health protection; and treatment reliability is enhan~ed.~

In the US., total and fecal coliforms are the most commonly used indicator organisms in reclaiimed water. The total coliform analysis includes organisms of both fecal and norifecal origin, while the fecal coliform analysis is specific for coliform organisms of fecal origin. Fecal coliforms are better indicators of fecal contamination than total coliforms, and the guidelines use fecal coliform as the indicator organism. Either the membrane filter technique or the multiple-tube fermentation technilque may be used to quantify the coliform levels in the reclaimed water.

The guidelines include limits for fecal coliform organisms but do not include parasite or virus lirnits. Parasites have not been shown to be a problem at reuse operations in the U.S. at the treatment levels and reclaimed water limits recommended in the guidelines, although definitive information on the presence and significance of the parasites Giardia and Crypfosporidium in reclaimed water is lacking. While viruses are a concem in reclaimed water, virus limits are not recommended in the guidelines for the following reasons: a significant body of information exists indicating that viruses are inactivated or removed to low or immeasurable levels via appropriate wastewater the identification and enumeration olf viruses in wastewater are hampered by relatively low virus recovery rates; there are a limited number of facilities having the personnel and equipment necessary to perform the analyses; the laboratory analyses can take as long as 4 weelks to complete; there is no consensus among public health experts regarding the health significance of low levels of viruses in reclaimed water; and there have not been any documented cases of viral disease resulting from the reuse of wastewater in the U.S.

It is explicitly stated in the Guidelines for Wafer Reuse that the recommended treatment unit processes and water quality limits presented in the guidelines "are not intended to be used as definitive water reclamation and reuse criteria. They are intended to provide reasonable guidance for water reuse opportunities, particularly in states that have not developed their own criteria or guidelines."

Conclusion

Untreated wastewater contains a wide variety of microbiological and chemical constituents, many of which can have an adverse impact on nonpotable water reuse applications. 'Treatment using conventional wastewater treatment processes has been shown to produce reclaimed water suitable and, in conjunction with proper design and operational controls, safe for almost all nonpotable types of reuse. Several reference documents are available that provide recommended water quality criteria for most nonpotable applications of reclaimed water. EPAs Guidelines for Wijlfer Reuse provide useful reference material, including a summary of state criteria and suggested guidelines directed principally at public health protection fmm pathogenic microorganisms.

51

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Culp, G., G. Wesner, R. Williams, and M.V. Hughes, Jr. 1980. Wastewater Reuse and Recycling Technology. Noyes Data Corporation, Park Ridge, New Jersey.

Ayers, R.S. and 1D.W. Westcot. 1985. Water Quality for Agriculture. FA0 Irrigation & Drainage Paper 29, Rev. 1, United Nations Food and Agriculture Organization, Rome, Italy.

University of California Committee of Consultants. 1974. Guidelines for Interpretation of Water Quality for Agriculture. Memo Report.

Page, A.L. and A.C. Chang. 1985. Fate of Wastewater Constituents in Soil and Groundwater: Trace Elements. In: Irrigation with Reclaimed Municipal Wastewater -A Guidance Manual. G.S. Pettygrove and T. Asano (eds.), pp. 13-1 - 13-16. Pirepared by the California State Water Resources Control Board. Published by Lewis Publishers, Inc., Chelsea, Michigan.

American Society of Civil Engineers. 1990. Agricultural Salinity Assessment and Management. Tanji, K.K. (ed.), New York, N.Y.

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

Palazzo, A.J. 1976. The Effects of Wastewater Applications on the Growth and Chemical Camposition of Forages. Report 76-9, US. Army Corps of Engineers, Cold IRegions Research and Engineering Laboratory, Hanover, New Hampshire.

Iwata, Y. and FA. Gunther. 1976. Translocation of the Polychlorinated Biphenyl Oroclor 1254 from Soil into Carrots under Field Conditions. Arc. of Environ. Contam. & Tox., 4( 1 ):44-59.

Pahren, H.R., J.B. Lucas, J.A. Ryan, and G.K. Dotson. 1979. Health Risks Associated with Land Application of Municipal Sludge. Jour. WPCF, 51(11):2588-2601,

Lau, L.S. and 1. VJu. 1992. New Drip Irrigation Technology for Wastewater Reuse. In: Proceedings of the Water Environment Federation 65th Annual Conference & Exposition - Volume IX, pp. 427-435, September 20-24, 1992, New Orleans, Louisiana. Published by the Water Environment Federation, Alexandria, Virginia.

Boyle Engineering Corporation. 1981. Evaluation of Agricultural Irrigation Projects Using Reclaimed Water. Califomia State Water Resources Control Board, Office of Water, Recycling, Sacramento, California.

Perry, T.C., A.R. Overman, T.A. Wheaton, and L.R. Parsons. 1991. Irrigation of Citrus With Reclaimed Water. Report prepared for the Florida Department of Environmental Regulation, Tallahassee, Florida.

56

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Adams, A.P., M. Garbett, H.B. Rees, and B.G. Lewis. 1978. Bacterial Aerosols from Cooling Towers. Jour. WPCF, 50(10):2362-2369.

Adams, A.P., M. Garbett, H.B. Rees, and B.G. Lewis. 1980. Bacterial Aerosols Produced from a Cooling Tower Using \Nastewater Effluent as Makeup Water. Jour. WPCF, 52(3):498-501.

State of Califomia. 1992. Draff Revisions to the Wastewater Reclamation Criteria. State of Califomia, Department of Health Service, Environmental Managment Branch, Sacramento, Califomia.

Florida Department of Environmental Regulation. 1990. Reuse of Reclaimed Water and Land Application. Chapter 17-610, Florida Administrative Code, Florida Department of Environmental Regulation, Tallahassee, Florida.

Sepp, E. 1971. The Use of Sewage for Irrigation-A Literature Review. Califomia Department of Public Health, Bureau olf Sanitary Engineering, Berkeley, California.

Lund, E. 1980. Healfh Problems Associated with the Re-Use of Sewage: 1. Bacteria, 11. Viruses, Ill. Protozoa and Helminths. Working papers prepared for WHO Seminar on Health Aspects of Treated Sewage Re-Use, 1-5 June 1980, Algers, Algeria.

Feachem, R.G., H. Bradley, H. Garelick, and D.D. Maira. 1983. Sanitation and Disease -Health Aspects of Excreta and Wastewater Management. Published for the World Bank by John Wley & Sons, Chichester, England.

Shuval, H.I., A. Adin, B. Fattal, E. Rawitz, and P. Yelutiel. 1986. Wastewater Irrigation in Developing Countries - Healfh Effects and Technical Solutions. World Bank Technical Paper Number 51, The World IBank, Washington, D.C.

Rose, J.B. and C.P. Gerba. 1991. Assessing Potential Health Risks from Viruses and Parasites in Reclaimed Water in Arizona and Florida, U.S.A. Waf. Sci. Tech.. 23:2091-2098.

Asano, T., Y.C. Leong, M.G. Rigby, and R.H. Sakaji. 1992. Evaluation of the Califomia Wastewater Reclamation Criteria using Etnteric Virus Monitoring Data. Waf. Sci. Tech., 26(7/8):1513-1524.

Yanko, W.A. 1993. Analysis of 10 Years of Virus Mlonitoring Data from Los Angeles County Treatment Plants Meeting Califomia Wastewater Reclamation Criteria. Water Environ. Research., 65(3):221-226.

Asano, T., R.G. Smith, and G. Tchobanoglous. 1985. Municipal Wastewater: Treatment and Reclaimed Water Characteristics. In: r'rrigation with Reclaimed Municipal Wastewater - A Guidance Manual, G.S. Pettygrove and T. Asano (eds.), pp. 2-1 - 2-26. Prepared by the California State Water Resources Control Board. Published by Lewis Publishers, Inc., Chelsea, Michigan.

Metcalf & Eddy, Inc. 1991. Wastewater Engineerifllg: Treatment, Disposal, Reuse. McGraw-Hill, Inc., NewYork, N.Y.

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Bausum, H.T., S.A. Schaub, R.E. Bates, H.L. McKim, P.W. Schumacher, and B.E. Brockett. 1983. Microbiological Aerosols From a Field-Source Wastewater Irrigaiion System. Jour. WPCF, 55(1):65-75.

Camann, D.E., 1B.E. Moore, H.J. Harding and C.A. Sorber. 1988. Microorganism Levels in Air Near Spray Irrigation of Municipal Wastewater: the Lubbock Infedtion Surveillance Study. Jour, WPCF, 60( 1 1): 1960-1 970.

Hoadley, A.W. anid S.M. Goyal. 1976. Public Health Implications of the Application of Wastewater to Land. In: Land Treatment and Disposal of Municipal and Industrial wastewater, p. 1092, R.L. Sanks and T. Asano (eds.), Ann Arbor Science Publishers, Inc., Ann Arbor, Michigan.

Sobsey, M. Cooling Waters. Report to NUS Corporation, Pittsburgh, PA.

1978. Public Health Aspects of Human Enteric Viruses in

Teltsch, B., S. Kiclmi, L. Bonnet, Y. Borenzstajn-Roten, and E. Katzenelson. 1980. Isolation and Identification of Pathogenic Microorganisms at Wastewater-Irrigated Fields: Ratios in Air and Wastewater. Applied Environ. MiCrObiOl., 39: 1 184-1 195.

Camann, D.E. anid M.N. Guentzel. 1985. The Distribution of Bacterial Infections in the Lubbock infection Surveillance Study of Wastewater Spray Irrigation. In: Proceedings of the Wafer Reuse Symposium 111, pp. 1470-1495, August 2-7, 1984, Denver, Colorado. Published by the A W A Research Foundation, Denver, Colorado.

Camann, D.E. and B.E. Moore. 1988. Viral Infections Based on Clinical Sampling at a Spray irrigation Site. in: Proceedings of Wafer Reuse Symposium IV, pp. 847-863, August 2-7, 1987, Denver, Colorado. Published by the A W A Research Foundation, Denver, Colorado.

Camann, D.E., DE. Johnson, H.J. Harding, and C.A. Sorber. 1980. Wastewater Aerosol and School Attendance Monitoring at an Advanced Wastewater Treatment Facility: Durham Plant, Tigard, Oregon. in: Wastewater Aerosols and Disease, pp. 160-179, H. Pahren and W. Jakubowski (eds.), EPA-600/9-80-028, U.S. Environmental Protection Agency, Cincinnati, Ohio.

Fannin, K.F., K.W. Cochran, D.E. Lamphiear and A.S. Monto. 1980. Acute Illness Differences with Regard to Distance from the Tecumseh, Michigan Wastewater Treatrnent Plant. In: Wastewater Aerosols and Disease, pp. 117- 135, H. Pahren and W. Jakubowski (eds.), EPA-600/9-80-028, U.S. Environmental Protection Agency, Health Effects Research Laboratory, Cincinnati, Ohio.

US. Environmentjal Protection Agency. 1980. Wastewater Aerosols and Disease. Proceedings of a Symposium, H. Pahren and W. Jakubowski (eds.), September 19-21, 1979, EPA-60019-80-028, US. Environmental Protection Agency, Health EfFects Research Laboratory, Cincinnati, Ohio.

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13.

14.

15.

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21

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24.

25.

Hurst, C.J., W.H. Benton, and R.E. Stetler. Water. Jour. A W A , 81(9):71-80.

Rose, J.B. 1986. Microbial Aspects of Wastewater Reuse for Irrigation. CRC Critical Reviews in Environ. Control, 16(3):231-256.

Riggs, J.L. 1989. AIDS Transmission in Drinking Water: N o Threat. Jour.

1989. Detecting Viruses in

A W A , 81(9):69-70.

Gover, N. 1993. HIV in Wastewater Not a Threat. Water Environ. & Tech., 5( 12):23.

Bryan, F.L. 1974. Diseases Transmitted by Falods Contaminated by Wastewater. In: Wastewater Use in the Production of Food and Fiber, pp. 16- 45. EPA-660/2-74-041, U.S. Environmental Protectioin Agency, Washington, D.C.

Shuval, H.I. 1978. Land Treatment of Wastewater in Israel. In: State of Knowledge in Land Treatment of Wastewater, Volume 1. Proceedings of an Infernational Symposium, pp. 429-436, U.S. Army Corps of Engineers, Cold Regions Research and Engineering Laboratory, Hanover, New Hampshire.

Murphy, W.H. and J.T. Syverton. 1958. Absorptioin and Translocation of Mammalian Viruses by Plants. II. Recovery and Distribution of Viruses in Plants. Virology, 6(3):623-636.

Gerba, C.P., and S.M. Goyal. 1985. Pathogen Removal from Wastewater during Groundwater Recharge. In: Artificial Recharge of Groundwater, pp. 283-317, T. Asano (ed.), Butteworth Publishers, Boslon, Massachusetts.

Keswick, B.H., C.P. Gerba, S.L. Secor, and I. Sech. 1982. Survival of Enteric Viruses and Indicator Bacteria in Groundwater. Jour. Environ. Sci Health, A17:903-912.

Jansons, J., L.W. Edmonds, B. Speight, and M.R. Bucens. 1989. Survival of Viruses in Groundwater. Water Research., 23(3):301-306.

Gerba, C.P., C. Wallis, and J.L. Melnick. 1975. Wastewater Bacteria and Viruses in Soil. Jour. lrig. and Drainage Div., ASC€, 101:157-174.

Johnson, D.E., D.E. Camaan, D.T. Kimball, R.J. Prevost and R.E. Thomas. 1980. Health Effects from Wastewater Aerosols at a New Activated Sludge Plant-John Egan Plant, Schaumburg, Illinois. In: Wastewater Aerosols and Disease, pp. 136-159, H. Pahren and W. Jakubowski (eds.), EPA-600/9-80- 028, U.S. Environmental Protection Agency, Cincinnati, Ohio.

Johnson, D.E., D.E. Camaan, J.W. Register, R.E. Thomas, C.A. Sorber, M.N. Guentzel, J.M. Taylor, and W.J. Harding. 1980 The Evaluation of Microbiological Aerosols Associated With the Applicistion of Wastewater to Land: Pleasanton, CA. EPA-600/1-80-015, U.S. Environmental Protection Agency, Cincinnati, Ohio.

53

Table I. Nonpotable Uses of Reclaimed Water ~~

Landscape IrriQation

Parks Cemeteries Golf Courses Roadway Rights-of-way School Grounds Greenbelts Residential Lawns

Aaricultural lrriaatiiz

Food Crops Fodder, Fiber, and Seed Crops Nurseries Sod Farms Silviculture Frost Protection

Industrial

Cooling Boiler Feed Stack Scrubbing Process Water

Groundwater R e c t e

Recharge Aquifers Salt Water Intrusion Control

Nonpotable Urban (Other than Irriaation)

Toilet and Urinal Flushing Fire Protection Air Conditioner Cooling Water Vehicle Washing Street Cleaning Decorative Fountains

Impoundments

Omamental Recreational

Environmental

Stream Augmentation Marshes Wetlands Fisheries

Miscellaneous

Aquaculture Snow-making Soil Compaction Dust Control Equipment Washdown Livestock Watering

61

Table 2. Infectious Agents Potentially Present in Raw Sewage ~~ ~

Pathogen Disease

Bacteria Shigella (4 spp.) Salmonella typhi Salmonella (1 700 serotypes) Vibro cholerae Escherichia coli (enteropathogenic) Yersinia enferocolifica Leptospira (spp.) Legionella Campylobacter jejune

Entamoeba histolytica Giardia lamblia Balantidium coli Cryptosporidium

Ascaris lumbricoides (roundworm) Ancylostoma duodenale (hookworm) Necator americanus (roundworm) Ancylostoma (spp.) (hookworm) Strongloides sfercoralis (threadworm) Trichuris trichiura (whipworm) Taenia (spp.) (tapeworm) Enterobius vermicularis (pinworm) Echinococcus granulosis (tapeworm)

Enteroviruses (72 types) (polio, echo, Coxsackie, new enteroviruses) Hepatitis A virus Adenovirus (47 types) Rotavirus (4 types) Parvovirus (3 types) Norwalk agent Reovirus (3 types) Astrovirus (5 types) Calicivirus (2 types) Coronavirus

Protozoa

Helminths

Viruses

Shigellosis (dysentery) Typhoid fever Salmonellosis Cholera Gastroenteritis Yersiniosis Leptospirosis Legionnaire's diseiase Gastroenteritis

Amebiasis (amebic dysentery) Giardiasis Balantisiasis (dysentery) Cryptosporidiosis, diarrhea, fever

Ascariasis Ancylostomiasis Necatoriasis Cutaneous larva migrams Strongyloidiasis Trichuriasis Taeniasis Enterobiasis Hydatidosis

Gastroenteritis, heart anomolies, meningitis, others Infectious hepatitis Respiratory disease, eye infections Gastroenteritis Gastroenteritis Diarrhea, vomiting, fever Not clearly established Gastroenteritis Gastroenteritis Gastroenteritis

Source: Adapted from Sagik et a1.'02 and Hurst et a/.''

62

Table 3. Infectious Doses of Selected Pathogens

Organism Infectious Dose

Escherichia coli (enteropathogenic) Clostridium perfrinlgens Salmonella typhi Vibrio cholerae Shigella flexneri 211 Entameoba histolytica Shigella dysentariae Giardia lamblia Cryptosporidium Ascaris lumbricoides Viruses

106 - 10'O 1 - 1010

io4 - 10' io3 - 10'

180 20 10

e10 1-10 1-10 1-10

Source: Adapted ,from Feachem et al." and Feachem et aI.'O3

Table 4. Microorganism Concentrations in Raw Wastewater

Concentration Organisms (number/l00 mL)

Fecal Coliforms Fecal streptococci Shigella Salmonella Helminth ova Enteric virus Giardia I'ambia cysts Entamoeba histolytica cysts

io4 - io9 10" - io6 1- 1,000

400 - 8,000 1 - 180

100 - 50,000

1 - 10 50 - io4

Source: Adapted lfrom various sources.

63

P

Table 5. Typical Pathogen Survival Times at 20-30 "C

Pathogen

Survival Time (days)

Fresh Water 8, Sewage Crops Soil

Viruses' Enterovirusesb

Bacteria Fecal coliforms' Salmonella spp.' Shigella spp." Vibrio cholerae"

Protozoa Entamoeba hisfolyfica cysts

<I20 but usually 4 0 4 0 but usually <I5 <IO0 but usually <20

<60 but usually <30 <60 but usually ~ 3 0 <30 but usually <IO <30 but usually <IO

<30 but usually < I5 <30 but usually < 15 <IO but usually <5 <5 but usually <2

<70 but usually'<20 <70 but usually <20

c20 but usually 4 0

<30 but usually<l5 <I 0 but usually <2 <20 but usually < I O

Helminths Ascaris lumbricoides eggs Many months <60 but usually e30 Many months

' In seawater, viral survival is less, and bacterial survival is very much less, than in fresh water. Includes polio, echo, and Coxsackie viruses. V. cholerae survival in aqueous environments is a subject of current uncertainty.

Source: Adapted from Feachem et

Table 6. (Guidelines for Interpretation of Water Quality for irrigation

Dearee of Restriction on Use Potential Inigation Problem Units None Slight to Moderate Severe

Salinity (affects crop water availability)

ECW dS/m e0.7 0.7-3.0 >3.0 TDS mglL <450 450-2000 >2000

Permeability (affects infiltrate rate of water into the sail. Evaluate using EC, and SAR together)

SAR = 0-3 and ECw = >0.7 0.7-0.2 c0.2 = 3-6 = 6-12 = 12-20 = 20-40

Specific ion toxicity (affects sensitive crops)

Sodium (Na) Surface irrigation Sprinkler irrigation

Chloride (CI) Surface irrigation Sprinkler irrigation

Boron (B)

Miscellaneous effects (affects susceptible crops)

Nitrogen (TOTAL-IN)

Bicarbonate (HCO,) (overhead sprinkling only)

PH

Residual chlorine (overhead sprinkling only)

= >1.2 1.2-0.3 c0.3 = 21.9 1.9-0.5 C0.5 = >2.9 2.9-1.3 c1.3 = >5.0 5.2-2.9 e2.9

SAR c3 3-9 >9 mglL <70 >70

mg/L <I40 140-350 >350 mglL 4 0 0 .IO0

mg/L c0.7 0.7-3.0 23.0

mglL <5 5-30 >30

mg/L c90 90-500 2500

Normal range 6.5-8.4

mg/L <1.0 1.0-5.0 >5.0

Source: Adapted from Ayers and Westcotso and University of California Committee of Cons~u~tants.~'

65

Tabk 7. Recommended Limits for Heavy Metals in Irrigation Water

Long-Term Use Short-Term Use Constituent “L) (mdL) Remarks

Aluminum

Arsenic

5.0 20 Can cause nonprcdudivity in acid soils, but soils at pH 5.5 to 8.0 will precipitate the ion and eliminate .toxicity.

0.10 2.0 Toxicity to plants varies widely, ranging from 12 mglL for Sudan grass to less than 0.05 mglL for rice.

Berylium 0.10 0.5 Toxicity to plants vanes, ranging from 5 mglL for kale to 0.5 mg/L for bush beans.

Boron m m

Cadmium

Chromium

Cobalt

0.75 2.0 Essential to plant growth, with optimum yields for many obtained at a few-tenth mg/L in nutrient solutions. Toxic to many sensitive plants (e.g., citrus) at 1 mglL. Usually sufficient quantities in reclaimed water to correct soil deficiencies. Mostgrasses relatively tolerant at 2.0 to 10 mg/L.

0.01 0.05 Toxic to beans, beets, and turnips at concentrations as low as 0.1 mglL in nutrient solution. Conservative limits recommended.

0.1 1 .o Not generally recognized as essential growth element. Conservative limits recommended due to lack of knowledge on toxicity to plants.

Toxic to tomato plants at 0.1 mglL in nutrient solution. Tends to be inactivated by neutral and alkaline soils.

0.05 5.0

Copper 0.2 5.0 Toxic to a number of plants at 0.1 mglL in nutrient solution.

Fluoride 1.0 15.0 Inactivated by neutral and alkaline soils.

Table 7. Recommended Limits for Heavy Metals in Irrigation Water (Cont'd.)

Long-Term Use Short-Term Use Constituent (mglL) ( m W Remarks

Iron 5.0 20.0 Not toxic to plants in aerated soils, but can contribute to soil acidification and loss of essential phosphorus and molybdendum.

Lead 5.0 10.0 Can inhibit plant cell growth at very high concentrations.

Lithium 2.5 2.5 Tolerated by most crops at up to 5 mglL; mobile in soil. Toxic to citrus at low doses - recommended limit is 0.075 mglL.

Manganese 0.2 10.0 Toxic to a number of crops at a fewtenths to a few mglL in acid soils.

8 Molybdenum 0.01 0.05 Nontoxic to plants at normal concentrations in soil and water. Can be toxic to livestock if forage is grown in soils with high levels of available molybdenum.

Nickel 0.2 2.0 Toxic to a number of plants at 0.5 to 1.0 mglL reduced toxicity at neutral of alkaline pH.

Selenium 0.02 0.02 Toxic to plants at low concentrations and to livestock if forage is grown in soils with low levels of added selenium.

Tin, Tungsten, & Titanium -- -- Effectively excluded by plants; specific tolerance levels unknown.

Vanadium 0.1 1 .o Toxic to many plants at relatively low concentrations.

Zinc 2.0 10.0 Toxic to many plants at widely varying concentrations; reduced toxicity at increased pH (6 or above) and in fine-textured or organic soils.

Source: Adapted from National Academy of Sciences - National Academy of Engineering.'

Table 8. Recommended Cooling Water Quality Criteria for Make-up Water to Recirculating Systems

Pamnetef Recommended1 Limit

CI 500 TDS 500 Hardness 650 Alkalinity 350 PH 6.9-9.0 COD 75 TSS 100 Turbiday 50 BOD 25 Organicsb 1 .o NH, - N 1 .o

4 50

PO4 SiO, AI 0.1 Fe 0.5 Mn 0.5 Ca 50 Mg 0.5 HCO, 24 - 3 0 4 200

All values in mglL except pH.

Source: Adapted from Water Pollution Control Foundation4 and Goldstein et

Methylene blue active substances.

a1.6~

68

Table 9. Relcommended Industrial Boiler-Feed Water Quality Criteria

Parameter" Low Intermediate High Pressure Pressure Pressure

( 4 5 0 psig) (150-700 psig) (e700 psig) ~

Silica 30 10 0.7 Aluminum 5 0.1 0.01 Iron 1 0.3 0.05 Manganese 0.3 0.1 0.01

0.4 0.01 Calcium 0.25 0.01 Magnesium H

Ammonia 0.1 0.1 0.1 Bicarbonate 170 120 48 Sulfate Chloride Dissolved soilds 700 500 200 Copper 0.5 0.05 0.05

0.01 0.01 Zinc Hardness 350 1 .o 0.07 Alkalinity 350 100 40

Methylene blue active substances 1 1 0.5 Carbon tetrachloride extract 1 1 0.5 Chemical oxygen dlemand 5 5 1 .o Hydrogen sulfide H H H

Dissolved oxygen 2.5 0.007 0.0007 Temperature, 'F H H H

Suspended solids 10 5 0.5

*

* Accepted as received (if meeting other limiting values); has never been a

H

** H ** H H H

H

pH, units 7.0-10.0 8.2-10.0 8.2-9.0

Recommended limits in mglL except for pH (units) and temperature (degrees Farenheit).

problem at conclentrations encountered.

Source: Adapted from US. Environmental Protection Agency."'

69

Table I O . Industrial Process Water Quality Requirements

Pulp & Paper Textile

Scouring, Mechanical Chemical, Pulp 8 Paper, Petroleum Sizing Parameter Pulping Unbleached Bleached Chemical & Coal Suspension Bleach & Dye Cement

c u 0.05 0.01 Fe 0.3 1 .o 0.1 0.1 1.0 . 0.3 0.1 2.5 Mn 0.1 0.5 0.05 0.1 0.05 0.01 0.5 Ca 20 20 68 75 Mg 12 12 19 30 CI 1,000 200 200 500 300 250

* HCO, 128 NO, 5 so, I00 250

35 SiO, 50 50 50 Hardness 100 100 250 350 25 25 Alkalinity 125 400 TDS 1,000 1,000 100 100 600 TSS 10 10 5 10 5 5 500 Color 30 30 10 20 5 5

CCE 1

* All values in mg/L except color and pH.

Source: Water Pollution Control Federation.'

PH 6-1 0 6-10 6-10 6.2-8.3 6-9 6.5-8.5

Table 11. C a l i i Treatment and Quality Criteria for Reuse

Type of Use Total Coliform Limits Treatment Required ~~

Fodder, Fiber, & Seed Crops - Surface Irrigation of Orchards and Vinyards

Primary

Pasture for Milking Animals 23/100 mL Oxidation & Disinfection Landscape Impoundments Landscape Irrigation (Golf Courses, Ceimeteries, etc.)

Surface Irrigation of Food Crops Restricted Landscape Impound- ments

2.2/100 mL

Spray Irrigation of Food Crops Landscape Irrigation (Parks, Playgrounds, etc.) Nonrestricted Recreational Impoundments

2.2/100 mL

Oxidation 8 Disinfection

Oxidation, Disinfection, Clarification, Filtration', & Disinfection

Groundwater Recharge Case-by-Case Case-by-Case Eva1 uation Evaluation

a The turbidity of filtered effluent cannot exceed an average of 2 turbidity units during any 24-hour period.

Source: State of (>aliforina."

71

Table 12. Florida Treatment and Quality Criteria for Reuse

Type of Use Water Quality Requirements Treatment Required

Restricted Public Access Areas"

Public Access Areasb Food Crop Irrigation' Toilet Flushingd Fire Protection Aesthetic Purposes Dust Control

Rapid Rate Land Application

200 fecal colill 00 mL 20 mglL TSS 20 mglL BOD

No detectable fecal Secondary, Disinfection, colill00 mL & Filtration 5 mglL TSS 20 mglL BOD

Secondary & Disinfection

200 fecal colill00 mL 20 mglL TSS 20 mglL BOD 12 mg/L Total N

Secondary & Disinfection

a Sod farms, forests, fodder crops, pasture land, or similar areas. Residential lawns, golf courses, cemeteries, parks, landscaped areas, highway medians, or similar areas. Only allowed if crops are peeled, skinned, cooked, or thermally processed before consumption. Only allowed where residents do not have access to plumbing system. Not allowed in single-family residences.

Source: Florida Department of Environmental Regulat i~n.~~

Table '13. Texas Reclaimed Water Qual i i Requirements

Type of Use Allowable Limits

Irrigation

Fodder, Fiber, & Seed Crops

Pasture for Milking Animals

30 mg/L BOD

20 mg/L BOD' 800 Fecal ColillOO mL

Food Cropsb

Restricted Landscape Areas

Unrestricted Landscape Areas

Landscape Impoundments Restricted Landscape Impoundments Ornamental Fountains

Commercial and lnldustrial Uses

Toilet Flushing Water

10 mg/L BOD' 3 NTU 75 Fecal ColillOO mL

20 mglL BOD' . 800 Fecal ColillOO mL

5 mglL BOD 3 NTU 75 Fecal ColillOO mL

10 mg/L BOD 3 NTU 75 Fecal ColillOO mL

20 mglL BOD' 200 Fecal ColillOO mL

5 mg/L BOD 75 Fecal ColillOO mL

a 30 mglL BOD for stabilization pond systems. Spray irrigation of food crops to be eaten raw is prohibited.

Source: State of 7'exas.'O0

73

Table 14. EPA Guidelines for Water Reiuse

Type of Use Treatment Reclaimed Water Quality

Urban Uses Food crops Eaten Raw Recreational Impoundments

Resrticted Access Area lnigation Processed Food Crops Nonfood Crops Aesthetic Impoundments Construction Uses Industrial Cooling' Environmental Reuse

Groundwater Recharge of Nonpotable Aquifers by Spreading

Groundwater Recharge of Nonpotable Aquifers by Injection

Groundwater Recharge of Potable Aquifers by Spreading

Groundwater Recharge of Potable Aquifers by Injection Augmentation of Surface Supplies

Secondary, Filtration, 8 Disinfection

Secondary 8 Disinfection

Site Specific 8 Use Dependent Primary (Minimum)

Site Specific & Use Dependent Secondary (Minimum)

Site SDecific

pH = 6-9 510 mgR BOD 4 NTU' No Detectable Fecal ColillOO mL 21 mglL CI, Residualb

pH = 6-9 40 mgR BOD G O mgR SS d:W Fecal Colill 00 mL 21 mgR CI, Residualb

Site Specific 8 Use Dependent

Site Specific & Use Dependent

Site SDecific secondary M'eet Drinking Water Disinfection (Minimum) Standards after

Percolation through Vadose Zone

Includes the following:

Filtration 4! NTU' Disinfection No Detectable Fecal AWT ColillOO mL

lnlcludes the following: Secondary pti 6.5-8.5

211 mgR Cl, Residualb Meet Drinking Water MCLs

a Should be met prior to disinfection. Should not exceed 5 NTU at any time. After a minimum contact time of 30 minutes. Once-through cooling.

Source: Adapted from U.S. Environmental Protection Agency.'