Water Reuse and Sustainability - InTechOpen

Water Reuse and Sustainability - InTechOpen

11 Water Reuse and Sustainability Rouzbeh Nazari1, Saeid Eslamian2 and Reza Khanbilvardi1 1City 2Isfahan University of New York University of Technol...

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11 Water Reuse and Sustainability Rouzbeh Nazari1, Saeid Eslamian2 and Reza Khanbilvardi1 1City 2Isfahan

University of New York University of Technology, 1USA 2Iran

1. Introduction Water reuse simply is the use of reclaimed water for a direct beneficial purpose in various sectors from home to industry and agriculture. For a number of semi-arid regions and islands, water reuse provides a major portion of the irrigation water. In addition, the reuse of treated wastewater for irrigation and industrial purposes can be used as strategy to release freshwater for domestic use, and to improve the quality of river waters used for abstraction of drinking water. Specific water reuse applications meet the water quality objectives. Water quality standards and guidelines which are related to irrigation and industrial water reuse are described in this chapter. Other reuse consumptions such as urban, recreational and environmental are also discussed. Water quality is the most important issue in water reuse systems in ensuring sustainable and successful wastewater reuse applications. The main water quality factors that determine the suitability of recycled water for irrigation are pathogen content, salinity, specific ion toxicity, trace elements, and nutrients. It will be introduced the important criteria for evaluation water quality and World Health Organization guidelines (WHO, 1989) and the United States Environmental Protection Agency guidelines (USEPA, 1992, 2004) which are the two main guidelines that frequently used in many countries around the world. Finally, it will be discussed briefly about different treatment method selections; the degree of treatment required and the extent of monitoring necessary which depend on the specific application. Wastewater reuse can be applied for various beneficial purposes such as agricultural irrigation, industrial processes, groundwater recharge, and even for potable water supply after extended treatment. Water reuse allows the communities to become less dependent on groundwater and surface water resources and can decrease the diversion of water from sensitive ecosystems. Additionally, water reuse may reduce the nutrient loads from wastewater discharges into waterways, thereby reducing and preventing pollution. This "new" water resource may also be used to replenish overdrawn water resources and rejuvenate or reestablish those previously destroyed. Most common types of wastewater reuses are summarized in Table 1.

2. Agriculture reuse The reuse of wastewater has been successful for irrigation of a wide array of crops, and increases in crop yields from 10-30% have been reported (Asano, 1998, 2004). For a number

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of semi-arid regions and islands, water recycling provides a major portion of the irrigation water. In addition, the reuse of treated wastewater for irrigation and industrial purposes can be used as strategy to release freshwater for domestic use, and to improve the quality of river waters used for abstraction of drinking water by reducing disposal of effluent into rivers (USEPA, 2003). By knowing that water for agriculture is critical for food security and also by understanding that agriculture remains the largest water user, with about 70% of the world’s freshwater consumption, it can be understood that how important it is to have new source of water available for this section. According to recent Food and Agriculture Organization data (FAO Website), only 30 to 40% of the world’s food comes from irrigated land comprising 17% of the total cultivated land. One of the broad strategies to address this challenge for satisfying irrigation demand under conditions of increasing water scarcity in both developed and emerging countries is to conserve water and improve the efficiency of water use through better water management and policy reforms. In this context, water reuse becomes a vital alternative resource and key element of the integrated water resource management at the catchment scale (Asano and Levine, 1996; Lazarova, 2000, 2001). However, despite widespread irrigation with reclaimed wastewater, water-reuse programs are still faced with a number of technical, economic, social, regulatory, and institutional challenges. Some of the water-quality concerns and evaluation of long-term environmental, agronomic, and health impacts remain unanswered. But water quality is the most important issue in water reuse systems so to ensure sustainable and successful wastewater reuse applications, the potential public health risk associated with wastewater reuse should be evaluated and also the specific water reuse applications should meet water quality objectives. Water quality of the effluent which is going to be used as reuse water, is the most important issue related to water reuse systems that determines the acceptability and safety of the use of recycled water for a given reuse application. The options for sustainable reuse projects are related to the quality of the effluent, and the environmental risk associated with land application for a variety of crops and activities and irrigation type and even the quality standard can vary during irrigation and non-irrigation period (Eslamian et al., 2010). It might be higher during interim periods when irrigation is not practiced to ensure a relatively safe discharge to receiving water bodies. The main water quality factors that determine the suitability of recycled water for irrigation are pathogen content, salinity, sodicity (levels of sodium that affect soil stability), specific ion toxicity, trace elements, and nutrients. All modes of irrigation may be applied depending on the specific situation. If applicable, drip irrigation provides the highest level of health protection, as well as water conservation potential (Valentina and Akica, 2005). The most important criteria for evaluation of the treated wastewater are as follows (Kretzschmar et al., 2002): -

Salinity (especially important in arid zones) Heavy metals and harmful organic substances Pathogenic germs

Table 1 presents the most important water quality parameters and their significance in the case of municipal wastewater reuse. The goal of each water reuse project is to protect public health without necessarily discouraging wastewater reclamation and reuse. The guidelines or standards required removing health risks from the use of wastewater and the amount and type of wastewater

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treatment needed to meet the guidelines are both contentious issues. The cost of treating wastewater to high microbiological standards can be so prohibitive that the use of untreated wastewater is allowed to occur unregulated.

Types of Reuse

Treatment

Urban Reuse Landscape irrigation, vehicle washing, toilet flushing, fire protection, commercial air conditioners, and other uses with similar access or exposure to the water Agricultural Reuse For Non-Food Crops Pasture for milking animals; fodder, fiber and seed crops

Secondary1 Filtration2 Disinfection3

Indirect Potable Reuse Groundwater recharge by spreading into potable aquifers

Site specific Secondary and disinfection (min.) May also need filtration and/or advanced wastewater treatment

Secondary Disinfection

Reclaimed Water Quality pH = 6–9 <10 mg/L biochemical oxygen demand (BOD) < 2 turbidity units (NTU)5 No detectable fecal coliform/100 mL4 1 mg/L chlorine (Cl2) residual (min.) pH = 6–9 < 30 mg/L BOD < 30 mg/L total suspended solids (TSS) < 200 fecal coliform/100 mL5 1 mg/L Cl2 residual (min.) Site specific meet drinking water standards after percolation through vadose zone.

Reclaimed Water Monitoring

Setback Distances

pH – weekly BOD – weekly Turbidity – continuous Coliform – daily Cl2 residual – continuous

50 feet (15 m) to potable water supply wells

pH – weekly BOD – weekly TSS – daily Coliform – daily Cl2 residual – continuous

300 feet (90 m) to potable water supply wells

pH – daily Turbidity – continuous Coliform – daily Cl2 residual – continuous Drinking water standards– quarterly Other – depends on Constituent

100 feet (30 m) to areas accessible to the public (if spray irrigation) site specific

1 Secondary treatment processes include activated sludge processes, trickling filters, rotating biological contactors, and many stabilization pond systems. Secondary treatment should produce effluent in which both the BOD and TSS do no exceed 30 mg/L. 2 Filtration means passing the effluent through natural undisturbed soil or filter media such as sand and anthracite. 3 Disinfection means the destruction, inactivation or removal of pathogenic microorganisms. It may be accomplished by chlorination, or other chemical disinfectants, UV radiation or other processes. 4 The number of fecal coliform organisms should not exceed 14/100 mL in any sample. 5 The number of fecal coliform organisms should not exceed 800/100 mL in any sample.

Table 1. Reuse Chart (USEPA, 2004)

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Parameter Total Suspended solids (TSS)

Organic indicators TOC Degradable Organics (COD, BOD) Nutrients N,P,K

Stable organics (e.g. phenols, pesticides, chlorinated hydrocarbons) pH Heavy metals (Cd, Zn, Ni, etc.) Pathogenic organisms

Dissolved Inorganics (TDS, EC, SAR)

Significance

Approximate Range in Treated Wastewater

TSS can lead to sludge deposits and anaerobic conditions. Excessive amounts caused clogging of irrigation systems. Measures of particles in wastewater can be related to microbial contamination, turbidity. Can interfere with disinfection effectiveness Measure of organic carbon. Their biological decomposition can lead to depletion of oxygen. For irrigation only excessive amounts cause problems. Low to moderate concentrations are beneficial.

< 1 to 30 mg/l

When discharged into the aquatic environment they lead to eutrophication. In irrigation, they are beneficial, nutrient source. Nitrate in excessive amounts, however, may lead to groundwater contamination. Some are toxic in the environment, accumulation processes in the soil.

N: 10 to 30 mg/l P: 0.1 to 30 mg/l

1 – 20 mg/l 10 – 30 mg/l

Affects metal solubility and alkalinity and structure of soil, and plant growth. Accumulation processes in the soil, toxicity for plants Measure of microbial health risks due to enteric viruses, pathogenic bacteria and protozoa

Coliform organisms: < 1 to 104 /100 ml other pathogens: Controlled by treatment technology

Excessive salinity may damage crops. Chloride, Sodium and Boron are toxic to some crops, extensive sodium may cause permeability problems

Table 2. Water quality parameters for wastewater reuse and their significance (Asano, 1998) Regulatory approaches stipulate water quality standards in conjunction with requirements for treatment, sampling and monitoring. These standards or guidelines are highly dependent on the kind of water use. Obviously, the landscape and forest irrigation has the lowest requirements concerning the treatment of effluent, compared to the potable reuse. But, the requirements of irrigation of limited crops (crops that need further processing) are not high and therefore it is applicable in economic terms. The greatest health concern when using recycled water for irrigation is related to pathogens that could be present (Kretschmer et al., 2000). It is widely known that it is not practical to establish the presence or absence of all pathogenic organisms in wastewater or recycled water in a timely fashion. For this reason, the indicator organism, E-coli, was established many years ago to allow monitoring of a limited number of microbiological constituents.

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Standards for wastewater reuse in many countries have been influenced by the WHO Health Guidelines (1989) (Table 3) and the USEPA Guidelines (2004) (Table 4). The Guidelines are set to minimize exposure to workers, crop handlers, field workers and consumers, and recommend treatment options to meet the guideline values. WHO’s 1989 Guidelines which seems somehow old and there are no any newer WHO guidelines; for the safe use of wastewater in agriculture take into account all available epidemiological and microbiological data. The fecal coliform guideline (e.g. =1000 FC/100 ml for food crops eaten raw) was intended to protect against risks from bacterial infections, and the newly introduced intestinal nematode egg guideline was intended to protect against helminthes infections (and also serve as indicator organisms for all of the large settable pathogens, including amoebic cysts). The exposed group that each guideline was intended to protect and the wastewater treatment expected to achieve the required microbiological guideline was clearly stated. Waste stabilization ponds were advocated as being both effective at the removal of pathogens and the most cost-effective treatment technology in many circumstances. Category

Reuse Conditions

A

Irrigation of crops likely to be eaten uncooked, sports fields, public parks

B

Irrigation of cereal crops, industrial crops, fodder crops, pasture and trees

C

Localized irrigation of crops in category B if exposure to workers and the public does not occur

Exposed Group

Workers, consumers, publics

Workers

None

Intestinal Nematode (arithmetic mean no. eggs per liter)

≤1

≤1

Not applicable

Fecal Coliforms (geometric mean no. per 100 ml)

Wastewater treatment expected to achieve the required microbiological guideline

≤ 1000

A series of stabilization ponds designed to achieve the microbiological quality indicated, or equivalent treatment

No standard recommendation

Retention in stabilization pond for 8-10 days or equivalent helminth and fecal coliform removal

Not applicable

Pretreatment as required by irrigation technology, but not less than primary sedimentation

Table 3. WHO (2001) guideline for use of treated wastewater in agriculture

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Treatment Water Quality Setbacks Monitoring Reuse Type ………………………………………………. Public Contact ……………………………………………….. Irrigation for public areas: Secondary * Weekly: pH, BOD * 50 feet to * pH 6-9 * Parks Filtration and * ≤ 10 mg/L BOD * Monthly: potable * Cemetery Disinfection Coliforms water * ≤ 2 NTU * Golf Courses * Continuously: * No detectable fecal * Other landscapes Turbidity, coliforms/100 mL Chlorine Residue * at least 1 mg/L Agricultural irrigation for: residual chlorine * Food crops that will not be commercially processed * Any crops eaten raw …………………………………………. Limited or No Public Contact…………………………………….. Irrigation of restricted Secondary * pH 6-9 * 300 feet to * Weekly: pH, BOD access areas: Disinfection * ≤ 30 mg/L BOD * Monthly: potable * Sod farms * ≤ 30 mg/L TSS Coliforms water * Silvicultures * ≤ 200 fecal and TSS * Other areas with limited coliforms/100 mL * 100 feet to * Continuously: or no public access Chlorine Residue areas * at least 1 mg/L accessible residual chlorine Agricultural irrigation to public for: ( if spray * Food crops that will be irrigation is commercially processed used) * Non-food crops and pastures

Table 4. USEPA (2004) guideline for agricultural reuse of wastewater In contrast, USEPA (2004) has recommended the use of much stricter guidelines for wastewater use in the USA. The USEPA (2004) has established guidelines to encourage states to develop their own regulations. The primary purpose of federal guidelines and state regulations is to protect human health and water quality. To reduce disease risks to acceptable levels, reclaimed water must meet certain disinfection standards by either reducing the concentrations of constituents that may affect public health and/or limiting human contact with reclaimed water. The elements of the guidelines applicable to reuse in agriculture are summarized in Table 4. For irrigation of crops likely to be eaten uncooked, no detectable fecal coliform/100 ml are allowed (compared to 1000 FC/100ml for WHO), and for irrigation of commercially processed crops, fodder crops, etc, the guideline is 200 FC/100 ml. Much wastewater reuse in agriculture is indirect and that is, the wastewater is predisposed into rivers and the contaminated river water is used later on for irrigation. However, international guidelines for the microbiological quality of irrigation water used on a particular crop do not exist (Ayers and Westcott, 1985). The United States Environmental Protection Agency (USEPA) recommended that the acceptable guideline for irrigation with natural surface water, including river water containing wastewater discharges, be set at 1000 FC/10 ml (USEPA, 1981). This standard has been adopted in some other countries as an irrigation water quality standard, for example, Chile, in 1978 (Ayers and Westcott, 1985). This standard is also consistent with guidelines for unrestricted irrigation. FAO has now recommended that the WHO (1989) Guidelines be used interim irrigation water standards, until more epidemiological information is available. Eslamian and Tarkesh-Isfahani (2010b) evaluate the most efficient irrigation systems in wastewater reuse.

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3. Industrial reuse Reuse of reclaimed water for industrial proposes is developed in many industries of United State of America, Europeans and other developed countries. Reclaimed water reuse is one of the strategies for sustainable management. Industrial reuse has increased substantially since the early 1990s for many of the same reasons urban reuse has gained popularity, including water shortages and increased populations, particularly in drought areas, and legislation regarding water conservation and environmental compliance. Utility power plants are ideal facilities for reuse due to their large water requirements for cooling, ash sluicing, rad-waste dilution, and flue gas scrubber requirements (Metcalf and Eddy, 2003, 2007). Petroleum refineries, chemical plants, and metal working facilities are among other industrial facilities benefiting from reclaimed water not only for cooling, but for processing needs as well. For the majority of industries, cooling water is the largest use of reclaimed water because advancements in water treatment technologies have allowed industries to successfully use lesser quality waters. These advancements have enabled better control of deposits, corrosion, and biological problems often associated with the use of reclaimed water in a concentrated cooling water system. The most frequent water quality problems in cooling water systems are corrosion, biological growth, and scaling. These problems arise from contaminants in potable water as well as in reclaimed water, but the concentrations of some contaminants in reclaimed water may be higher than in potable water (EPA, 1981). Industrial reuse can be explained and defined for a number of industries in the world, but if the most industrial water consumption, cooling towers, is considered to this subject, the industrial reuse is defined for each industry and it can be defined as a quality standard for reclaimed water reuse. Eslamian and Tarkesh-Isfahani (2010a) evaluate the urban reclaimed water for industrial reuses in North Isfahan, Iran. Based on this and other research projects results on eight various industries, and case studies, articles and books, reclaimed water quality parameter limitation for use in cooling towers are defined and shown in Table 5. Parameter

Measured Standard Method

Platinum Electrode, number 2510 B of Standard methods EDTA Titrimetric, number 2340 C of standard methods Titrimetric, number 2320 B of standard Alkalinity methods Argentometric, number 4500-Cl- B of Chloride standard methods Orthophosphate Vanadomolybdophosphoric Acid (PO4) Colorimetric, number 4500-P C of Vanadomolybdophosphoric Acid Colorimetric, polyphosphate number 4500-P C of standard methods Colorimetric, number 4500-NO2- B of NO2 standard methods Ultraviolet Spectrophotometric, number 4500NO3NO3- B of standard methods NH3 Nesslerization, number D1426 of ASTM Gravimetric, number 2540 D of standard TSS methods

Electrical conductivity (EC) Hardness (as CaCo3)

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Unit

Selected Range of Concentration for IOR Consumed

µmhos/cm

500-600

mg\L

150-250

mg\L

100-150

mg\L

175-250

mg\L

0-1

mg\L

Good

mg\L

<1

mg\L

<5

mg\L

<1

mg\L

5-10

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Ecological Water Quality – Water Treatment and Reuse Turbidity TDS Ca BOD5 COD pH SO42Na+ (as NaCl) Cr Cu Se Mn Pb Zn Mg Co Cd Fe Sr As Hg SiO2

Oil and Greece

Nephelometric, number 2130 B of standard methods Platinum Electrode, number 2510 B of Standard methods EDTA Titrimetric, number 3500-Ca B of standard methods Respirometric, number 5210 D of standard methods Closed Reflux-Titrimetric, number 5220 C of standard methods Electrometric, number 4500-H+ B of standard methods Gravimetric, number 4500-SO42- C of standard methods Direct Air-Acetylene Flame Atomic Absorption Spectrometric, number 3111 B of standard methods number 3111 B of standard methods number 3111 B of standard methods number 3111 B of standard methods number 3111 B of standard methods number 3111 B of standard methods number 3111 B of standard methods number 3111 B of standard methods number 3111 B of standard methods number 3111 B of standard methods number 3111 B of standard methods number 3111 B of standard methods number 3111 B of standard methods number 3111 B of standard methods Molybdosilicate Colorimetric, number 4500SiO2 C of standard methods Partition- Gravimetric, number 5520 B of standard methods DPD Colorimetric, number 4500-Cl G of standard methods

Total Chlorine Residual Total coliform (as log) Fecal coliform (as log) SRB (sulfate reducing bacteria) Gas Chromatographic-Flame Ionization PAHs Detector THMs Gas Chromatographic-Mass Spectrometry Gas Chromatographic-Flame Ionization MTBE Detector Gas Chromatographic-Electron Capture OCP-Pesticide Detector Gas Chromatographic-Nitrogen OPP-Pesticide Phosphorous Detector 2,4-D High Performance Liquid Chromatographic

NTU

<2

mg\L

250-500

mg\L

50-75

mg\L

0-5

mg\L

20-40

-

6-8

mg\L

0-250

mg\L

150.200

mg\L mg\L mg\L mg\L mg\L mg\L mg\L mg\L mg\L mg\L mg\L mg\L mg\L

<0.5 <0.05-1 <1 <0.3-1 <1 <1 <20-30 <1 <0.1-1 0.1-0.3 <1 <1 <1

mg\L

<10-20

mg\L

<1

mg\L

<4

Log MPN/100ml Log MPN/100ml MPN/100ml

<2.2 MPN/100ml <2.2 MPN/100ml nil

µg/L

nil

µg/L

nil

µg/L

nil

µg/L

nil

µg/L

nil

µg/L

nil

Table 5. Range of water quality parameters for reuse of reclaimed water in cooling towers

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4. Urban reuse Urban reuse systems are a crucial part of water recycling since it can provide the reclaimed water for various non-drinking purposes such as Irrigation of public parks and recreation centers, athletic fields, school yards and playing fields, highway medians and shoulders, and landscaped areas surrounding public buildings and facilities, Irrigation of landscaped areas surrounding single-family and multi-family residences, general wash down, and other maintenance activities. Urban reuse can be expanded to cover commercial uses such as vehicle washing facilities, laundry facilities, window washing and mixing water for pesticides, herbicides, liquid fertilizers, toilet and urinal flushing in commercial and industrial buildings. Reclaimed water can also help with human health and safety in dust control and concrete production for construction projects and control the expansion of suspended particles in the air and provide water for fire hydrants. A 2-year field demonstration/research garden compared the impacts of irrigation with reclaimed versus potable water for landscape plants, soils, and irrigation components. The comparison showed few significant differences; however, landscape plants grew faster with reclaimed water (Lindsey et al., 1996). But such results are not a given. Elevated chlorides in the reclaimed water provided by the City of St. Petersburg have limited the foliage that can be irrigated (Johnson, 1998). Dual distribution systems could be used to deliver the reclaimed water to customers through a parallel network of distribution completely separated and marked to distinguish from the community’s drinking water line. Design considerations for urban water reuse systems should include two major components: water reclamation facilities and reclaimed water distribution system, including storage and pumping facilities. The reclaimed water distribution system has the potential to become a third water utility, along with drinking water and wastewater. Reclaimed water systems are operated, maintained, and managed in a manner similar to the drinking water system. One of the oldest municipal dual distribution systems in the U.S., in St. Petersburg, Florida, has been in operation since 1977. The system provides reclaimed water for a mix of residential properties, commercial developments, industrial parks, a resource recovery power plant, a baseball stadium, and schools. The City of Pomona, California, first began distributing reclaimed water in 1973 to California Polytechnic University and has since added two paper mills, roadway landscaping, a regional park and a landfill with an energy recovery facility. As part of planning of an urban reuse system, communities have the option of choosing continuous or interruptible reclaimed water system. In general, an interruptible source of reclaimed water can be used as long as reclaimed water will not be used as the only source of fire protection. For example, the City of St. Petersburg, Florida, decided that an interruptible source of reclaimed water would be acceptable, and that reclaimed water would provide only backup for fire protection. If a community determines that a noninterruptible source of reclaimed water is needed, then reliability, equal to that of a potable water system, must be provided to ensure a continuous flow of reclaimed water. This reliability could be ensured through a municipality having more than one water reclamation plant to supply the reclaimed water system, as well as additional storage to provide reclaimed water in the case of a plant upset. However, providing the reliability to produce a non-interruptible supply of reclaimed water will have an associated cost increase. In some cases, such as the City of Burbank, California, reclaimed water storage tanks are the only source of water serving an isolated fire system that is kept separate from the potable fire service. Retrofitting a developed urban area with a reclaimed water distribution system

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can be expensive. In some cases, however, the benefits of conserving potable water may justify the cost.

5. Environmental and recreational reuses Water reuse provides a dependable, locally-controlled water supply and tremendous environmental benefits. Environmental reuse includes creating artificial wetlands, enhancing natural wetlands and sustaining stream flows. Uses of reclaimed water for recreational purposes range from landscape impoundments, water hazards on golf courses, to full-scale development of water-based recreational impoundments, incidental contact (fishing and boating) and full body contact (swimming and wading). As with any form of reuse, the development of recreational and environmental water reuse projects will be a function of a water demand coupled with a cost-effective source of suitable quality reclaimed water. In California, approximately 10 percent (47.6 mgd) (2080 l/s) of the total reclaimed water use within the state was associated with recreational and environmental reuse in 2000 (Leverenz et al., 2002). In Florida, approximately 6 percent (35 mgd or 1530 l/s) of the reclaimed water currently produced is being used for environmental enhancements, all for wetland enhancement and restoration (Florida Department of Environmental Protection, 2002). In Florida, from 1986 to 2001, there was a 53 percent increase (18.5 mgd to 35 mgd or 810 l/s to 1530 l/s) in the reuse flow used for environmental enhancements (wetland enhancement and restoration). Two examples of large-scale environmental and recreational reuse projects are the City of West Palm Beach, Florida, wetlands-based water reclamation project and the Eastern Municipal Water District multipurpose constructed wetlands in Riverside County, California. Other applications of environmental and recreational water reuse include creation of natural and man-made wetlands, recreational and aesthetic impoundments and stream augmentation. The objectives of these reuse projects are typically to create an environment in which wildlife can thrive and develop an area of enhanced recreational or aesthetic value to the community through the use of reclaimed water. Other benefits of environmental reuse include decreasing wastewater discharges and reducing and preventing pollution. Recycled water can also be used to create or enhance wetlands and riparian habitats.

6. Economic considerations One the major aspects of water reuse is the socio economic impacts assessment of implementation of such resources. Wastewater can decrease impacts of water shortage in arid and semi-arid regions of the world and promote means of sustainable development in the world. However, this will be highly dependent of environmentally sound implementation and management for reuse systems. Poor planning and management could leave significant damages on health and environment by contaminating valuable drinking water supplies and bring unwanted socio economic losses. Economic sustainability and public reception depend on the usage of reclaimed water. Most researches and surveys (Angelakis et al., 2001; Mantovani et al., 2001), have concluded that the best practices are those that substitute reclaimed water in lieu of potable water for use in irrigation, environmental restoration, cleaning, toilet flushing, and industrial uses. The main benefits of using reclaimed water in these situations are conservation of water resources and pollution reduction. Treating and reusing wastewater is economically reasonable in terms of

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increasing the water availability and the benefits of saving the environment from discharge of wastewater into other systems and controlling the spread of contamination into water and soil. Demand for municipal, industrial and agriculture is on the rise and are expected to reach 37, 23, and 340 bcm; respectively. Provided the low consumptive use of the municipal and industrial sectors, most of the appropriated water can be recovered (Kretschmer et al., 2003). In the agricultural sector, the large size of withdrawals encourages the collection and reuse of irrigation water. Wastewater is already in use around the world. In China, Chile and Mexico, extensive agriculture lands around are irrigated by wastewater (Sadik et al., 1994; Xie et al., 1993). Arab regions have also practicing wastewater reuse. About 7 bcm of wastewater was reused in 1996 out of 191 bcm the total withdrawal that year; this implies less than 4% recovery. Reused agriculture drainage was about 5 bcm out of 168 bcm withdrawn for that sector, less than 3% recovery and 2 bcm of municipal and industrial wastewater out of 23 bcm withdrawn, about 9% recovery (El-Ghamam, 1997). Wastewater is a source real economic activity involving local and federal government along with private industries. Various entities invest in getting rid of it or suffer the environmental damage. Either practice has a pervasive impact on public health and the sustainability of development. If wastewater is properly treated and reused, solves two major of saving local and regional environment and resolving water shortage. Over all the economic viability of water reuse has to be studied individually and the required treatment and cost efficiency, depend on type of pollutants, concentration and type of reuse.

7. Public health concerns and acceptance The major emphasis of wastewater reclamation and reuse has been on non-drinking applications so far, such as agricultural and landscape irrigation, industrial cooling and inbuilding applications, such as toilet flushing, in large commercial buildings. Indirect or direct potable reuse raises more public concern because of real or perceived perception of aesthetics and long-term health concerns. Regardless, the value of water reuse is weighed within a context of larger public issues of necessity and opportunity and will not be implemented until two major problems of public health concerns and public acceptance is resolved. Each of these problems involves various issues from scientific concerns to human psychology. In the case of public health concerns, which are extremely viable concerns, presence of pathogenic organism and inorganic micro pollutants should be carefully examined for their short and long term impacts. Pathogens could impose serious threat to human health. They are found in water as bacteria, protozoa, helminthes and ruses which some of them can be easily detected and removed (Dishman et al., 1989). However, others are more difficult to detect and removed and there are not enough studies to assign a safe concentration limits to them. Furthermore, the risk of viral infections and waterborne diseases in general is still an unresolved issue. The inorganic pollutants of concerns in water reuse are nitrates, other nitrogen compounds and heavy metals which are easy to detect and remove. Organic micro pollutants also represent a large problem in direct potable reuse mainly because of lack of sufficient information on the health significance of many the known or suspected carcinogenic, mutagenic, allergenic, teratogenic organic compounds found in water (Crook, 1985). It is also necessary to mention that there are thousands of organic compounds in water that are awaiting discovery (Golden, 1984; Dishman et. al., 1989). The second problem that the potable use of reclaimed water has to facing is public acceptance. This a major obstacle to

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reuse and it roots in educational and psychological barriers which have to overcome in order to obtain public support. Numerous researches have highlighted the fact that public is not welcoming in this regard and most of the polls revealed major opposition to direct potable use (Gallup, 1973; Kasperson et al., 1974; Carley, 1985). The general feeling about use of wastewater for drinking purposes is negative, regardless of the degree of treatment and these feelings embody the psychological factors in the public’s rejection of direct potable use of reclaimed water.

8. Conclusions The world’s population is on the rise and is expected to increase dramatically between now and the year 2020 (United Nations, 2006). This growth will put more pressure on our already scarce and damaged water resources. Communities around the world will be faced with an increased level of wastewater production with no use. Water reclamation and reuse can offer significant help for conserving and extending available water supplies. Water reuse may also present communities with an alternate wastewater disposal method as well as providing pollution abatement by diverting effluent discharge away from sensitive surface waters. However, water reuse has its own advantages and disadvantages which have been summarized in Table 6. Advantages This technology reduces the demands on drinkable sources of freshwater.

The technology may diminish the volume of wastewater discharged, resulting in a beneficial impact on the aquatic environment. Capital costs are low to medium for most systems and are recoverable in a very short time; this excludes systems designed for direct reuse of sewage water. Operation and maintenance are relatively simple except in direct reuse systems where more extensive technology and quality control are required

Disadvantages If implemented on a large scale, revenues to water supply and wastewater utilities may fall as discharge of wastewaters is reduced. Reuse of wastewater may be seasonal in nature, resulting in the overloading of treatment and disposal facilities during the rainy season. Application of untreated wastewater as irrigation water or as injected recharge water may result in groundwater contamination. Health problems, such as water-borne diseases and skin irritations, may occur in people coming into direct contact with reused wastewater In some cases, reuse of wastewater is not economically feasible because of the requirement for an additional distribution system.

Provision of nutrient-rich wastewaters can increase agricultural production in water-poor areas.

Gases, such as sulfuric acid, produced during the treatment process can result in chronic health problems.

It may reduce the need for large wastewater treatment systems, if significant portions of the waste stream are reused or recycled.

Table 6. Advantages and disadvantages of water reuse

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Ecological Water Quality - Water Treatment and Reuse Edited by Dr. Voudouris

ISBN 978-953-51-0508-4 Hard cover, 496 pages Publisher InTech

Published online 16, May, 2012

Published in print edition May, 2012 This book attempts to cover various issues of water quality in the fields of Hydroecology and Hydrobiology and present various Water Treatment Technologies. Sustainable choices of water use that prevent water quality problems aiming at the protection of available water resources and the enhancement of the aquatic ecosystems should be our main target.

How to reference

In order to correctly reference this scholarly work, feel free to copy and paste the following: Rouzbeh Nazari, Saeid Eslamian and Reza Khanbilvardi (2012). Water Reuse and Sustainability, Ecological Water Quality - Water Treatment and Reuse, Dr. Voudouris (Ed.), ISBN: 978-953-51-0508-4, InTech, Available from: http://www.intechopen.com/books/ecological-water-quality-water-treatment-and-reuse/water-reuse-andsustainablity

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