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TREATED WASTEWATER REUSE

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Presentation on theme: "TREATED WASTEWATER REUSE"— Presentation transcript:

1 TREATED WASTEWATER REUSE
INTRODUCTION: 1. MANAGING WATER SECURITY BY WATER REUSE Water Reuse for Irrigation (Agriculture, Landscape and Turf Grass), Valentina Lazarovoa and Akica Bahri

2 MANAGING WATER SECURITY BY WATER REUSE
Growing water scarcity, rapid increase in population, rapid urbanization and megacity development, increasing competition among water users, and growing concerns for health and environmental protection are examples of important issues. According to the International Water Management Institute (IWMI), by 2025, 1.8 billion people will live in countries or regions with absolute water scarcity.

3 MANAGING WATER SECURITY BY WATER REUSE
The term ‘‘absolute water scarcity’’ means water availability of less than the 100m3 / inhabitant/year that is necessary for domestic and industrial use. Today, most countries in the Middle East and North Africa can be classified as having absolute water scarcity. By 2025, these countries will be joined by Pakistan, South Africa, large parts of India and China, and a number of other regions.

4 MANAGING WATER SECURITY BY WATER REUSE
Water for agriculture is critical for food security. Agriculture remains the largest water user, with about 70% of the world’s freshwater consumption. According to recent Food and Agriculture Organization (FAO) data, only 30 to 40% of the world’s food comes from irrigated land comprising 17% of the total cultivated land. The demand and pressure for irrigation are increasing to satisfy the required growth of food production, because there is little growth in cultivated areas worldwide (0.1%/year).

5 MANAGING WATER SECURITY BY WATER REUSE
One of the broad strategies to address this challenge to satisfy 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. New management strategies of irrigation must be developed and well integrated in the global water cycle.

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7 MANAGING WATER SECURITY BY WATER REUSE
These sources can be classified in two major groups with specific advantages and constraints: Natural sources of irrigation water: Rainwater accounts for an important portion of the water used to satisfy irrigation demand. However, its contribution could be considered important only in temperate climates under specific climate conditions and, predominantly, at small scale.

8 MANAGING WATER SECURITY BY WATER REUSE
Surface water (lakes and rivers) plays a major role for irrigation in both temperate and dry climates. However, surface water resources are becoming more and more limited, and their effective use often requires the construction of dams and reservoirs with negative environmental impact. Water from aquifers has local and regional importance, but in many cases is associated with a progressive decrease in the water table level and withdrawal of nonrenewable fossil groundwater.

9 MANAGING WATER SECURITY BY WATER REUSE
Alternative sources of irrigation water: Desalination has relatively low importance for irrigation because of its high cost; thus, it is limited to only a few small-scale cases in islands and coastal areas. Reuse of municipal wastewater and drainage water is a cost competitive alternative, with growing importance for irrigation in all climatic conditions at both small and large scales.

10 MANAGING WATER SECURITY BY WATER REUSE
Consequently, for a number of countries where current freshwater reserves are or will be in the near future at a critical limit, recycled water is the only significant low-cost alternative resource for agricultural, industrial, and urban non-potable purposes: The contribution of water reuse is expected to reach 10 to 13% of the water demand in the next few years in Australia, California, and Tunisia.

11 MANAGING WATER SECURITY BY WATER REUSE
In Jordan, the volume of recycled water is expected to increase by more than three- or fourfold by the year 2010. A more than tenfold increase in recycled water volume is expected in Egypt by the year 2025. Many countries have included water reuse as an important dimension of water resource planning (e.g., Australia, Jordan, Israel, Saudi Arabia, Tunisia, the United States). Over 1.7 Mm3 of recycled water are reused each day in California and Florida, mainly for irrigation of agricultural crops and landscaping.

12 MANAGING WATER SECURITY BY WATER REUSE
Millions of hectares of cropland are irrigated with sewage effluent in China, India, and Mexico, in many cases without adequate treatment. (It is worth noting that irrigation with untreated wastewater leads to bacterial and viral diseases and helminth infections. For this reason, the choice of appropriate treatment of wastewater and the implementation of sound irrigation practices are the two major actions necessary to protect the public health and prevent nuisance conditions and damage to crops, soils, and groundwater).

13 2. ROLE OF WATER REUSE FOR IRRIGATION
The majority of the water reuse projects developed in the world are for agricultural irrigation. In some arid and semi-arid countries, such as Jordan, the reuse of treated municipal wastewater provides a large share of irrigation water. In this particular sector, water reuse becomes a vital resource to enhance agricultural production, providing a number of additional benefits such as increased crop yields, improved health safety, and decreased reliance on chemical fertilizers.

14 2. ROLE OF WATER REUSE FOR IRRIGATION
Recycled water can be used for many purposes. The list presented in Table 1.1 provides an overview of the major uses. It is important to stress that all irrigation uses for crops, landscapes, and lawns can be satisfied with recycled water if the appropriate management practices are applied.

15 2. ROLE OF WATER REUSE FOR IRRIGATION

16 2. ROLE OF WATER REUSE FOR IRRIGATION
Recycled water has successfully irrigated a wide array of crops with a reported increase in crop yields from 10 to 30%. Indeed, water reuse for irrigation conveys some risks for health and environment, depending on recycled water quality, recycled water application, soil characteristics, climate conditions, and agronomic practices.

17 3. BENEFITS AND CONSTRAINTS OF IRRIGATION WITH RECYCLED WATER
Table 1.2 summarizes some of the most important benefits of water reuse, as well as the major constraints for implementation of water reuse projects. For the successful implementation of water reuse, the main advantages should be balanced against negative impacts or other constraints.

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19 3. BENEFITS AND CONSTRAINTS OF IRRIGATION WITH RECYCLED WATER
Benefits to be gained from the retrofit of landscape irrigation to recycled water use are numerous and may be greater than the benefits of agricultural irrigation. There are several reasons for this: Most expanses of irrigated turf are located within or adjacent to cities where effluent water is produced, so transportation costs are lower. Recycled water is produced continuously, and, depending on climate, the turf grass ‘‘crop’’ may be continuous (i.e., uninterrupted by cultivation, seeding, or harvest, all of which mean stopping irrigation for considerable periods).

20 3. BENEFITS AND CONSTRAINTS OF IRRIGATION WITH RECYCLED WATER
Turf grasses absorb relatively large amounts of nitrogen and other nutrients often found in higher quantities in recycled water than in freshwater. This characteristic may greatly decrease the potential for groundwater contamination by use of recycled water. Depending on recycled water quality, potential health problems arising from the use of recycled water would appear to be less common when water is applied to turf than when it is applied to food crops.

21 3. BENEFITS AND CONSTRAINTS OF IRRIGATION WITH RECYCLED WATER
Soil-related problems that might develop due to the use of recycled water would have less social and economic impact if they develop where turf is cultivated than if they develop where food crops are grown.

22 4. SPECIFICS OF WATER REUSE PLANNING
Numerous state-of-the-art technologies enable wastewater to become a sustainable water resource for a number of reuse purposes and thus allow high quality freshwater to be reserved for domestic uses. The key components of successful water reuse planning include not only the technical know-how and good engineering design, but also a rigorous market analysis and economic, environmental, and social considerations.

23 4. SPECIFICS OF WATER REUSE PLANNING
Whether water reuse will be appropriate in a given situation depends on careful economic considerations, potential types of water reuse, stringency of wastewater discharge requirements, and public policy and acceptance. The main issue to be considered during water reuse planning is a good definition of project objectives and its ability to resolve existing problems and expected benefits (Figure 1.2).

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25 4. SPECIFICS OF WATER REUSE PLANNING
It is wise to adopt a systematic and holistic approach when planning a water reuse project from the very beginning. Planning usually evolves through three main phases (Figure 1.3): Phase I: Conceptual planning Phase II: Feasibility investigations Phase III: Facility planning

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27 4. SPECIFICS OF WATER REUSE PLANNING
It is wise to adopt a systematic and holistic approach when planning a water reuse project from the very beginning. Planning usually evolves through three main phases (Figure 1.3): Phase I: Conceptual planning Phase II: Feasibility investigations Phase III: Facility planning

28 4. SPECIFICS OF WATER REUSE PLANNING
The conceptual planning, phase I (Figure 1.4), is not an in-depth study; however, it is a very important step. It consists of a preliminary evaluation of the feasibility of implementing the water reuse concept in a local context. The most important step is the definition of project objectives. Having a clear vision of the possibilities offered by water reuse to water resource management is a major prerequisite to any project development.

29 4. SPECIFICS OF WATER REUSE PLANNING
A feasibility study (phase II) comprises more detailed analyses of water resources and needs: water demand projections, wastewater treatment and disposal needs, and the reclaimed water market. A set of scenarios is selected as the outcome of the conceptual planning phase, and some new alternatives are elaborated upon after the market analysis. Scenarios without water reuse or recycling with the mobilization of other alternative water sources should also be included in this phase (e.g., desalination, construction of hydraulic infrastructures such as dams).

30 4. SPECIFICS OF WATER REUSE PLANNING
Fewer solutions are selected for the third phase (phase III) facilities planning. Phase III involves complementary investigations on the aspects insufficiently analyzed during the previous phases. The best alternative is selected after a detailed comparison of the scenarios investigated. Specific attention is paid to economic feasibility on the basis of a cost/benefit analysis. Openness and transparency of water reuse planning is an essential part of the public information program that will reduce the potential for opposition to the project.

31 4. SPECIFICS OF WATER REUSE PLANNING
The project should be reviewed not only by the participants (owners, funding, engineers, regulatory agencies), but also by local authorities, potential customers, water user associations, and politicians. At the end of the planning, all the basic data and results from the feasibility analysis should be documented in the engineering report.

32 4. SPECIFICS OF WATER REUSE PLANNING
The multi-criteria screening and evaluation of alternative reuse and non-reuse options involve the following feasibility criteria: Engineering feasibility: possibility for implementation of wastewater treatment, storage, and distribution. Economic feasibility: reasonable investment and O&M costs Financial feasibility: available funding and subsidies

33 4. SPECIFICS OF WATER REUSE PLANNING
Environmental impact: potential negative effects on soils, groundwater, crops, or ecosystems, as well as environmental benefits Institutional feasibility: water policy, water rights, regulations, enforcement Social impact and public acceptance: support by stakeholders Market feasibility: who will use recycled water and under what conditions

34 5. MANAGEMENT ACTIONS FOR IMPROVEMENT OF IRRIGATION WITH RECYCLED WATER
The success of water reuse projects and, in particular, irrigation with recycled water depends greatly on the implementation of proper management practices. The main management actions could be structured in three major groups (Figure 1.4): 1. Policy and institutional measures 2. Engineering initiatives 3. Agronomic practices

35 5. MANAGEMENT ACTIONS FOR IMPROVEMENT OF IRRIGATION WITH RECYCLED WATER
For each group of measures, management actions can be categorized in three levels, depending on the final objective (see Figure 1.4): Health protection measures, including improved design and operation of wastewater treatment and reuse facilities Good practices to improve food production and quality of turf grass and landscape ornamentals, as well as recommended actions to prevent degradation of soils and water bodies Management practices aiming to improve economic competitiveness and consequently to enhance public acceptance.

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37 6. TERMINOLOGY In the literature, and in governmental regulations, a variety of terms have been used for individual constituents of concern in wastewater. The terminology used commonly for key concepts and terms in the field of wastewater management is summarized in Table 1 a.

38 Term Definition Biosolids Class A biosolids b Class B biosolids b Primarily an organic, semisolid wastewater product that remains after solids are stabilized biologically or chemically and are suitable for beneficial use. Biosolids in which the pathogens (including enteric viruses, pathogenic bacteria, and viable helminth ova) are reduced below current detectable levels. Biosolids in which the pathogens are reduced to levels that are unlikely to pose a threat to public health and the environment under specific use conditions. Class B biosolids cannot be sold or given away in bags or other containers or applied on lawns or home gardens.

39 Term Definition Characteristics (wastewater) Composition Constituents c Contaminants Disinfection Effluent Impurities General classes of wastewater constituents such as physical, chemical, biological, and biochemical. The makeup of wastewater, including the physical, chemical, and biological constituents. Individual components, elements, or biological entities such as suspended solids or ammonia nitrogen. Constituents added to the water supply through use. Destruction of disease-causing microorganisms by physical or chemical means. The liquid discharged from a processing step.

40 Term Definition Nonpoint sources Point sources Nutrient Parameter Pollutants Reclamation Sources of pollution that originate from multiple sources over a relatively large area. Pollutional loads discharged at a specific location from pipes, outfalls, and conveyance methods from either municipal wastewater treatment plants or industrial waste treatment facilities. An element that is essential for the growth of plants and animals. Nutrients in wastewater, usually nitrogen and phosphorus, may cause unwanted algal and plant growths in lakes and streams. A measurable factor such as temperature. Constituents added to the water supply through use. Treatment of wastewater for subsequent reuse application or the act of reusing treated wastewater.

41 Term Definition Recycling Repurification Reuse Sludge Solids
Treatment of wastewater for subsequent reuse application or the act of reusing treated wastewater. Treatment of wastewater to a level suitable for a variety of applications including indirect or direct potable reuse. Beneficial use of reclaimed or repurified wastewater or stabilized biosolids. Solids removed from wastewater during treatment. Solids that are treated further are termed biosolids. Material removed from wastewater by gravity separation (by clarifiers, thickeners, and lagoons) and is the solid residue from dewatering operations. a Adapted, in part, from Crites and Tchobanoglous (1998). b U.S. EPA (1999). c To avoid confusion, the term “constituents” is used in this text in place of contaminants, impurities, and pollutant


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