- Email: [email protected]
Development of analysis tools for social, economic and ecological effects of water reuse
Desalination 218 (2008) 81–91
Development of analysis tools for social, economic and ecological effects of water reuse A. Urkiagaa, L. de las Fuentesa*, B. Bisb, E. Chiruc, B. Balaszd, F. Hernándeze a
GAIKER Centro Tecnológico, Parque Tecnológico, Edificio 202, 48100 Zamudio, Spain Tel. +34 946002323; Fax +34 946002324; email: [email protected] b Institute of Environmental Protection, University of Lodz, Banacha 12/16, PL-90237 Lodz, Poland c Apa Nova Bucuresti S.A., Aristide Demetriad 2, 70706 Bucharest, Romania d GEONARDO Environmental Technologies Keve u. 17, 1031 Budapest, Hungary e Institute of International Economics, University of Valencia, Campus dels Tarongers, 46022 Valencia, Spain
Received 1 February 2006; accepted 16 August 2006
Abstract The full implementation of the Urban Waste Water Treatment Directive (91/271/EEC) in Europe will contribute to obtain treated wastewaters of quite high quality that could be reused for certain applications or improved by polishing steps for uses with higher quality requirements. Even though reclaimed water reuse is currently implemented in many European countries, mainly for irrigation, its potential has not yet been exploited in many areas. In fact, a decisive factor to achieve a higher percentage of water reuse is the establishment of effective incentives, which in many instances will be of either an economic or a regulatory nature. The limiting factor for water reuse can in many circumstances be the quality of the water available linked to the treatment processes (technology) and potential hazards for secondary users. In any case, its economic viability needs a careful cost-benefit analysis for the various parties involved to be carried out. However, some water reuse implementation projects have failed because some other key factors, such as social awareness or associated ecological effects, were not accounted for. Thus, the consideration of regulatory, economic, technological, social and environmental factors seems essential to successfully accomplish a reclaimed water reuse project. Feasibility studies can contribute to obtain the success in the implementation of a water reuse project. Within AQUAREC a feasibility study methodology for the performance of water reuse projects has been developed, considering the above mentioned key factors and providing the tools for their analysis. These guidelines aim at assisting the different stakeholders (administration, engineering companies, water management bodies, etc.) involved in the implementation of a water reuse programme in a specific area. AQUAREC Handbook on Feasibility Studies for Water Reuse Systems, publicly available, deals with all information
*Corresponding author. Presented at AQUAREC 2006 — Integrated Concepts for Reuse of Upgraded Wastewater, Barcelona, 1–3 February 2006 0011-9164/08/$– See front matter © 2008 Published by Elsevier B.V. doi:10.1016/j.desal.2006.08.023
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needs necessary to successfully face a water reuse project. Background information data collection support, technology options evaluation or environmental impact assessment guidelines are offered in this publication. Furthermore, the assessment methodologies and indicators for social, economic and environmental factors are also provided. Last but not least, cost effectiveness analysis methodologies and technology validation are also addressed. Keywords: Water reuse; Economic; Social; Environmental; Feasibility
1. Introduction 1.1. Main considerations on water reuse Different recent international forums have clearly noted that water will be one of the central issues of the 21st century in the globe, and thus the life of billions of people will depend on its wise management. Water is an essential and basic human need for urban, industrial and agricultural use and has to be considered as a limited resource. Only 1% of the world total water resources are fresh water and in 2025 nearly one-third of the population of developing countries — some 2.7 billion people — will live in regions of severe water scarcity. They will have to reduce the amount of water used in irrigation and transfer it to the domestic, industrial and environmental sectors. Moreover, water pollution by human interference, e.g. by industrial effluents, agricultural pollution or domestic sewage, will increase and the world’s primary water supply will need to increase by 41% to meet the needs of all sectors which will be largely due to the increase in the world population. In this scenario, a unique and viable opportunity to augment traditional water supplies provides water reclamation and reuse, the only solutions to close the loop between water supply and wastewater disposal. Promising is the fact that since many years it is feasible to treat wastewater to a high quality. Hence, wastewater could be regarded as a resource that could be put to beneficial use rather than wasted. Water reuse accomplishes two fundamental functions: the treated effluent is used as a water
resource for beneficial purpose and the effluent is kept out of streams, lakes, and beaches thus reducing pollution of surface water and groundwater. In addition to the economic savings, valuable substances and heat recovery can be achieved by water recycling favouring a zero emission process. One fundamental advantage of water reuse is the fact that in many cases the resource employed is available in the vicinity of its prospective new use, i.e. urban agglomerations and industrial sites. The limiting factor for water reuse can in many circumstances be the quality of the water available linked to the treatment processes (technology) and potential hazards for secondary users. The practise of waste water reuse is increasing greatly within the EU, mostly to alleviate the lack of water resources in certain regions, such as in Southern European countries, but also to protect the environment especially in coastal waters by removing all discharges into fragile receiving waters. In this sense, the full implementation of the Urban Waste Water Treatment Directive (91/ 271/EEC) in Europe will contribute to obtain treated wastewaters of quite high quality amenable for reuse. In fact, Article 12 of the Directive mentions that treated water shall be reused whenever appropriate. However, at present there are no supra-national regulations on wastewater reuse in Europe. Depending on water origin and treatment process, water reuse applications can be divided in seven categories. These categories, in order of significance (number of implemented projects), and their main constraints are shown in Table 1. The
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Table 1 Categories of water reuse and main constraints [1] Wastewater reuse categories
Potential constraints
1. Agricultural irrigation • Crop irrigation • Commercial nurseries 2. Landscape irrigation • Parks • School yards • Freeway medians • Golf courses • Cemeteries • Greenbelts • Residential uses
Surface and groundwater pollution if not properly managed Marketability of crops and public acceptance Effect of water quality, particularly salts, on soil and crops Public health concerns related to pathogens (bacteria, viruses, and parasites) Use area control including buffer zone. High costs for user may result
3. Industrial recycling and reuse • Cooling • Boiler feed • Process water • Heavy construction
Constituents in reclaimed wastewater related to scaling, corrosion, biological growth and fouling Public health concerns, particularly aerosol transmission of pathogens in cooling water
4. Ground water recharge • Ground water replenishment • Salt water intrusion control
Organic chemicals in reclaimed wastewater and their toxicological effects Total dissolved solids, nitrates, and pathogens in reclaimed wastewater
5. Recreational/environmental uses • Lakes and ponds • Marsh enhancement • Stream flow augmentation • Fisheries • Snowmaking
Health concerns of bacteria and viruses Eutrophisation due N and P in receiving water Toxicity to aquatic life
6. Non potable urban uses • Fire protection • Air conditioning • Toilet flushing
Public health concerns on pathogens transmitted by aerosols Effect of the quality on scaling, corrosion, biological growth, and fouling Cross connection
7. Potable reuse • Blending in water supply reservoir • Pipe to pipe water supply
Constituents in reclaimed wastewater, especially trace organic chemicals and their toxicological effects Aesthetics and public acceptance Health concerns about pathogen transmission, particularly viruses
largest application is the irrigation of crops, golf courses and sports fields. Water from recycling systems used in each one of the seven categories should fulfil four criteria: hygienic safety, aesthetics, environmental tolerance as well as technical and economical feasibility. Nevertheless, the potential for water reuse and recycling has not yet been fully exploited in many European areas. A decisive factor to achieve a
higher percentage of water reuse is the establishment of effective incentives, which in many instances will be of either an economic or a regulatory nature. Water reuse has to be considered in the first stages of an Integrated Water Resources Management Project. To examine its economic viability, a careful cost-benefit analysis for the various parties involved needs to be carried out regarding
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mainly technology aspects. But some water reuse implementation projects have failed because some other key factors, such as social awareness or associated ecological effects, were not accounted for. Thus, the consideration of regulatory, economic, technological, social and environmental factors seems essential to successfully accomplish a reclaimed water reuse project. 1.2. Feasibility studies methodology Feasibility studies can contribute to obtain successfully completed water reuse projects. A feasibility study is defined as an evaluation or analysis of the potential impact of a proposed project or program and is conducted to assist decision–makers in determining whether or not to implement a particular project or program. It is based on extensive research on the current practices and the proposed project/program and its impact. Accordingly, it will contain extensive data related to financial and operational impact and will include advantages and disadvantages of both, the current situation and the proposed plan. Within AQUAREC, a water reuse feasibility study methodology — summarised in Fig. 1 — has been developed considering regulatory, economic, technological, social and environmental factors. This methodology is publicly available in AQUAREC Handbook on Feasibility Studies for Water Reuse Systems [2]. The aim of this handbook is to offer a useful methodology to assist the different stakeholders (administration, engineering companies, water management bodies, etc.) involved in the implementation of a water reuse programme in a specific area and to provide the needed tools to address a water reuse feasibility study for a specific purpose. 2. Information collection When facing a feasibility study it is fundamental to count with different reliable data values, indicators or information of very different nature. Some basic records to be collected include:
• Water supply and demand (local and seasonal). • Water and wastewater management agencies in the area. • Regional water and wastewater facilities (in operation and planned). • Water cost and quality requirements. • Environmental setting (climate, geography and topography, water resources –surface and groundwater). • Land use and population (current state and projections). • Structure and location of potential users. • Ecological and hydro-geological boundary conditions. • Water related socio-economic facts (water supply restrictions on domestic, industrial and/or irrigation uses) • Status of public acceptance of water reuse. To obtain this information it is necessary to contact with the main stakeholders (different water-related institutions, organisations and associations) in the evaluated zone such as water and wastewater agencies, regional environmental agencies, councils and regional governments (land and population projections, funding options, etc.), farmers associations, end-users associations, etc. Moreover, different maps (boundaries, location of water and wastewater facilities, location of water sources, zones of land uses, possible users of the reclaimed water and population zones, geological zones, etc.) should also be compiled. The location of the water supply and wastewater facilities is crucial. In addition, the correct identification/location of its users and the reclaimed water flow and quality demands will also be key factors as they will condition the treatment, storage, piping and distribution needs, being one of the most relevant items to consider in the economical evaluation of the proposal. In order to integrate recorded data and maps the utilisation of Geographical Information System (GIS) tools is extremely useful (Fig. 2). Socio-economic facts and other data like water supply restrictions on domestic, industrial and
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EXECUTIVE SUMMARY
BACKGROUND INFORMATION
PROPOSED SYSTEMS
COMPARISON OF THE CURRENT AND PROPOSED SYSTEMS
CONCLUSIONS AND RECOMMENDATIONS
PROPOSED PROJECT SCHEDULE
ANNEXES
Fig. 1. General structure of a water reuse feasibility study [2].
Fig. 2. Dimension image (GIS) of a specific area [2].
• Characteristics of the zone • Integrated water balance of the zone/region/ catchment • Characteristics of the water supply and sanitation • Seasonal variations – past and future trends • Quality standards for effluent and reused water • Potential users of reclaimed water • Literature review • Description of each proposed system (advantages, disadvantages, requirements, basic layout) • Equipment’s needs and costs • Site possibilities • Environmental and sociological studies • Impact on population, industry, agriculture, tourism, hygiene and water quality • Selection of the alternatives • Result of computer network modeling analysis • Summary of probable costs and cost effectiveness analysis • Financial options
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irrigational uses or cost and prices for water supply and sewerage might be compiled too. Furthermore, other aspects such as price of power in the zone, climate and level of incomes of the population should also be recorded as they could probably determine the type of treatment to implement. The data scope should cover a wide period of time (from 20 to at least 5 years) so as to predict and consider the trend of each parameter (rainfall, temperature, water resources, water demand, population, land uses, wastewater quality, water prices and so on). The implementation of a water reuse project will certainly alter existing planning concepts, especially the potable water supply and distribution systems which are usually foreseen for a long time. Moreover, wastewater treatment plants are usually planned to operate for at least 20 years so as the quality of the reclaimed water will depend on the treatment itself these forecasts should be accounted for. Lastly, other civil works such as piping, storage tanks, etc. must be correctly sized to fulfil with the future needs (10–20 years). In summary, the executed projections must be realistic and cover a wide period of time. Status of public acceptance of water reuse is another important issue that needs consideration. In fact, many water reuse projects have not succeeded for not considering social opinion with regard to the project or over estimate the acceptance and needs of the final users. Public acceptance can change depending on the water reuse application. For instance, water reuse for landscape irrigation, agricultural uses and industrial applications are usually well or relatively well accepted whereas reuse for indirect potable uses is not well considered. Moreover educational (unknown effectiveness, potential risks, etc.) and socio-economic considerations (perception of water as an unlimited cheap resource, etc.) and religious issues should also be considered. In order to improve the social acceptance of water reuse, information about its benefits (environmental, economic, etc.) together with a train-
ing session on the key terms (water, wastewater, reclaimed water, water treatment, water quality, etc) should be promoted. Direct information has proved to have a positive influence in users’ willingness and a higher level of income and education are positively correlated with a respondent’s willingness to use recycled water. In any case, cost and risks are usually the main aspects to determine social acceptance.
3. Proposed water reuse options The choice of the right wastewater treatment technology is the most important step in planning a water reuse system because it is the key means of decreasing its potential risk that compiles environmental, technical, social and economical risks as shown in Fig. 3. Amongst the risks linked to reclaimed water use, the possible transmission of infectious diseases by pathogens is the most important concern. Besides, the environmental risk is connected with the contamination amenable to be found in the upgraded wastewater. In summary, the environmental impact assessment (EIA) of a water reuse project may address the following groups of risk: 1. Substantial alteration of land use; 2. Conflict with the land use plans or policies regulations; 3. Adverse impact on wetlands; 4. Affection of endangered species or their habitat; 5. Populations displacement or alteration of existing residential areas; 6. Anthagonistic effects on a flood-plain or important farmlands; 7. Adverse effect on parklands, reserves, or other public lands designated to be of scenic, recreational, archaeological, or historical value; 8. Significant contradictory impact upon ambient air quality, noise levels, surface or groundwater quality or quantity;
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ENVIRONMENT
ENVIRONMENTAL SAFETY
ENGINEERING
ECONOMIC LOSSES
TECHNICAL VIABILITY
TECHNICAL FAILURE
ENVIRONMENTAL FAILURE
RISKS
ECONOMY
ECONOMIC EFFECTIVENESS
SOCIETY
SOCIAL DISRUPTION
SOCIAL EQUITY
Fig. 3. Risks and objectives for sustainable water reuse [3].
9. Substantial adverse impacts on water supply, fish, shellfish, wildlife, and their actual habitats. Accordingly, the fundamental purpose of water treatment is to protect the consumer from pathogens and from impurities in the water that may be injurious or offensive to human health. Where appropriate, treatment should also remove impurities which, although not harmful to human health, may make the water unappealing, damage pipes, plant or other items with which the water may come into contact, or render operation more difficult or costly. Apart from water quality requirements, the applied technology or technologies to provide with reclaimed water will vary depending on many other factors such as economical aspects (treatment cost, economical level of the population and richness of the country), land requirements, power price, climate conditions, distances among the wastewater production place and water reuse site, size of the plant, flow design, flow seasonality, previously implemented systems and so on.
In Table 2 an overview of the different unit processes yielding reclaimed water for different applications is given. In summary, combining the various processes and operations it is now possible to produce high quality water from municipal wastewater for any reuse application. However, the feasibility of such wastewater reuse program will depend mainly on public acceptance and cost.
4. Water reuse costs and financing A common misconception in planning for water reclamation and reuse is that reclaimed water represents a low-cost new water supply. This assumption is generally true only when water reclamation facilities are conveniently located near large agricultural or industrial users and when no additional treatment is required beyond the existing water pollution control facilities from which reclaimed water is delivered. The conveyance and distribution systems for reclaimed water represent the principal cost of most water reuse projects.
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Table 2 Overview of main unit processes and operations used in water reclamation [1] Process Solid/liquid separation Sedimentation
Filtration
Description
Application
Removal of particulate matter, chemical flocs and precipitates from suspension by gravity settling. Particle removal by passing water through sand or other porous medium.
Removal of particles > 30 µm from turbid water.
Biological treatment Aerobic biological treatment Biological metabolism by microorganisms in an aeration basin or biofilm process Ponds up to one metre in depth for mixing Oxidation pond and sunlight penetration. Biological nutrient removal
Waste stabilisation ponds
Disinfection
Advanced treatment Activated carbon Air stripping Ion exchange
Chemical coagulation and precipitation
Lime treatment
Membrane filtration Reverse osmosis
Combination of aerobic, anoxic, and anaerobic processes to optimise conversion of organic and ammonia nitrogen to molecular nitrogen (N2) and phosphorus removal. Pond system consisting of anaerobic, facultative and maturation ponds linked in series to increase retention time. The inactivation of pathogenic organisms using oxidizing chemicals, ultraviolet light, caustic chemicals, heat, or physical separation processes (e.g. membranes). Contaminants are physically adsorbed onto the activated carbon surface. Transfer of ammonia and other volatile components from water to air. Exchange of ions between an exchange resin and water using a flow through reactor.
Removal of particles > 3 µm from turbid water. Frequently used after sedimentation or coagulation/flocculation Removal of dissolved and suspended organic matter from wastewater. Reduction of suspended solids, BOD, pathogenic bacteria, and ammonia from wastewater. Reduction of nutrient content in reclaimed water.
Reduction of suspended solids, BOD, pathogenic bacteria, and ammonia from wastewater. Facilitates water reuse for irrigation and aquaculture. Protection of public health by removal of pathogenic organisms.
Removal of hydrophobic organic compounds Removal of ammonia and some volatile organics from water Effective for removal of cations such as calcium, magnesium, iron, ammonium, and anions such as nitrate Formation of phosphorus precipitates and flocculation of particles for removal by sedimentation and filtration.
Use of aluminium or iron salts, polyelectrolytes, and/or ozone to promote destabilization of colloidal particles from reclaimed water and precipitation of phosphorus. Use of lime to precipitate cations and metals Used to reduce scale-forming potential of water, precipitate phosphorus, and modify from solution. pH. Removal of particles and microorganisms Micro-, nano-, and ultrafiltration from water. Removal of dissolved salts and minerals Membrane system to separate ions from solution based on reversing osmotic pressure from solution; also effective for pathogen removal. differentials.
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A recent study in California indicates that the amortised cost of reclaimed water is about 0.44 €/m3, excluding operation and maintenance costs. This reclaimed water is normally too expensive for traditional agricultural irrigation in the United States and most other countries; only landscape irrigation and other urban applications can afford to pay for the water. The different water reuse options should be compared with the conventional non-reuse alternative. In most cases there is not a single most suitable option. Two or more different types of treatments and water reuse applications are often recommended. The probable cost for implementing a water reuse alternative requires the investigation of four primary cost components: • Distribution of the reclaimed water • Additional treatment at the wastewater plant, if required, above the requirements necessary to achieve water quality standards for discharge of the effluent • Storage systems and pressure maintenance of the regenerated water, and • Water quality monitoring and additional administration for maintaining two water systems
Investment costs account for 45–75% of the total cost of a water reuse project [1]. Comparison of reclaimed water costs with a similar compilation of costs for a freshwater supply system provides a measure of cost-effectiveness of a reuse project. The cost effectiveness of reuse projects is directly related to the volume of reclaimed water used: the more water utilised, the more cost-effective the project. In this sense irrigation generally provides the highest potential of water reuse. However, reuse costs should also integrate external costs of an environmental or social nature [4,5] usually not considered. Accordingly, funding and management of a water reuse system is a key element for a feasible
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implementation. The funding mechanisms can be split in two related categories: 1. Financing of up-front costs (i.e. initial capital investment) 2. Financing of ongoing operating costs (i.e. revenue programmes during the operation to cover debt service and operation and maintenance costs). The EU does not have specific subsidies to encourage water reuse. Basically there are six European programmes or organisations that are likely to finance water recycling projects: European Investment Bank (EIB), Short and Mediumterm Priority Environmental Action Programme (SMAP), Financial Instrument for the Environment (LIFE), Community Initiative of the European Regional Development Fund (especially, Urban II), Structural Funds (FEDER) and Cohesion Fund. Alternatively, the Interreg Programme is also available.
5. Social, environmental and economical impact assessment Using reclaimed water in place of fresh water for existing uses can free up existing water supply system capacity to cater for new water needs. This results in savings in the cost of developing new water sources, water transfers and treatment and distribution systems. It can also result in significant improvements in downstream river water quality. The different socio-environmental and economical benefits resulting from water conservation and reuse include [6]: (a) agriculture benefits such as: (i) reduced diversion costs, (ii) value of a secure “drought proof” supply of reclaimed water, (iii) increased farm production, and (iv) value of reclaimed water nutrients, i.e. savings in fertiliser applications and pesticides;
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(b) urban water supply benefits such as: (i) savings in the capital cost of diversion structures, drought storage, transfer systems and water treatment and (ii) savings in distribution, operation and maintenance costs including pumping energy, and treatment chemicals; (c) urban wastewater benefits such as: (i) savings in discharge pump stations and pipelines (ii) savings in treatment and nutrient removal costs required for discharge to sensitive waters (iii) savings in operation and maintenance costs (heat recovery, chemicals); (d) environmental water quality benefits such as: (i) reduction in freshwater diversions – more river flow for downstream users – better downstream water quality (ii) reduction in pollutant discharges (iii) better downstream water quality – reduced environmental impact and improved river aesthetics – reduced impacts on fisheries and aquatic life – improved public health for downstream users – lower water treatment costs for downstream users – improved recreational values of waterways (iv) reduction of the potential salinity intrusion risk in groundwater aquifers (v) improvement of the ecosystem and increase of the fauna and flora species due to the creation of new recreational zones, parks, gardens and green areas (vi) improvement of the quality of the seawater and beaches e) increase in the tourist activity due to the good quality of the seawater and beaches and quantity of golf courses, sport fields, swimming pools, recreational zones, etc. f) decrease in raw materials, reagents, and water
or heat consumption due to water recycling in the industry. Decrease in the environmental penalties that these industries should pay for the wastewater discharge. g) increase of the quality of life of the population due to (i) the increase of recreational zones, parks, gardens, sport fields, golf courses, etc. (ii) the improvement of the sanitary and health quality of the water (decrease of the diseases related to the water), (iii) the improvement of the environment (iv) the decrease or restrain in the water price due to the non needed water diversion infrastructures (v) the increase of the employment due to the creation of new jobs direct and indirectly related with water reuse. New employments related with the increase of the tourist or agricultural activity in the zone, maintenance of new green areas (parks, gardens and recreational zones) and more directly connected to the operation and maintenance of the wastewater treatment plants, water engineering companies, suppliers of systems, equipment and chemicals for wastewater treatment and water reuse. Within AQUAREC, 25 different indicators have been proposed to evaluate reclaimed water reuse-related social (6), economical (4) and environmental (15) aspects. These indicators can be further analysed through a semi-quantitative assessment (especially for social and environmental indicators) by associating each one of them to a range of colours or values (Table 3) and for which technical expertise in the indicator evaluation is needed. Furthermore, a tentative reference assessment scale must be established to measure the feasibility of each project. It is assumed beforehand that all indicators have identical weight, which is a simplistic approach. Alternatively, the proposed indicators can be
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book on Feasibility Studies for Water Reuse Systems that can be downloaded from www.acquarec. org website. This work is part of the AQUAREC project Integrated Concepts for Reuse of Upgraded Wastewater (EVK1-CT-2002-00130) funded by the EESD Programme of the European Commission.
Table 3 Classification of impacts of water reuse indicators using semi-quantitative assessment [2]
Range (Produced impact)
Value
Very negative Slightly negative No change Slightly positive Very positive
–2 –1 0 1 2
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References [1] T. Asano, ed., Wastewater Reclamation and Reuse, Technomic Publishing Inc., Lancaster, PA, 1998. [2] AQUAREC, ed., Handbook on Feasibility Studies for Water Reuse Systems. [3] J. Ganoulis, Evaluating alternative strategies for wastewater recycling and reuse in the Mediterranean area. Wat. Sci. Tech.: Water Supply, 3(4) (2003) 11–19. [4] G. Louis and M. Siriwanada, A procedure for calculating the full cost of drinking water. CEWorld-a virtual, American Society of Civil Engineers, 2001, www.ceworld.org. [5] S. Renzetti, Full Cost Accounting for Water Supply and Sewage Treatment: A Case Study of the Niagara Region, Canada. World Bank’s Resources Management Group on Economic Instruments, 2003, www.worldbank.org. [6] J. Anderson, The environmental benefits of water recycling and reuse. Wat. Sci. Tech.: Water Supply, 3(4) (2003) 1–10.
used in a quantitative assessment in which the weight of each indicator is implicitly included in its individual reference scale, like in Table 4 where the social indicator number 2 (quality of life) is ranked regarding its compliance against guiding values of the Bathing Water Directive (100% = full compliance). This assessment should be completed with community and stakeholder consultation to prove public acceptance of the water reuse project proposal. 6. Final comments and acknowledgements The information provided in this paper is more profusely dealt with within AQUAREC Hand-
Table 4 Example of score rating for water reuse indicators using quantitative assessment [2]
Score
0
1
2
3
4
5
6
7
8
9
10
SI2
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Development of analysis tools for social, economic and ecological effects of water reuse A. Urkiagaa, L. de las Fuentesa*, B. Bisb, E. Chiruc, B. Balaszd, F. Hernándeze a
GAIKER Centro Tecnológico, Parque Tecnológico, Edificio 202, 48100 Zamudio, Spain Tel. +34 946002323; Fax +34 946002324; email: [email protected] b Institute of Environmental Protection, University of Lodz, Banacha 12/16, PL-90237 Lodz, Poland c Apa Nova Bucuresti S.A., Aristide Demetriad 2, 70706 Bucharest, Romania d GEONARDO Environmental Technologies Keve u. 17, 1031 Budapest, Hungary e Institute of International Economics, University of Valencia, Campus dels Tarongers, 46022 Valencia, Spain
Received 1 February 2006; accepted 16 August 2006
Abstract The full implementation of the Urban Waste Water Treatment Directive (91/271/EEC) in Europe will contribute to obtain treated wastewaters of quite high quality that could be reused for certain applications or improved by polishing steps for uses with higher quality requirements. Even though reclaimed water reuse is currently implemented in many European countries, mainly for irrigation, its potential has not yet been exploited in many areas. In fact, a decisive factor to achieve a higher percentage of water reuse is the establishment of effective incentives, which in many instances will be of either an economic or a regulatory nature. The limiting factor for water reuse can in many circumstances be the quality of the water available linked to the treatment processes (technology) and potential hazards for secondary users. In any case, its economic viability needs a careful cost-benefit analysis for the various parties involved to be carried out. However, some water reuse implementation projects have failed because some other key factors, such as social awareness or associated ecological effects, were not accounted for. Thus, the consideration of regulatory, economic, technological, social and environmental factors seems essential to successfully accomplish a reclaimed water reuse project. Feasibility studies can contribute to obtain the success in the implementation of a water reuse project. Within AQUAREC a feasibility study methodology for the performance of water reuse projects has been developed, considering the above mentioned key factors and providing the tools for their analysis. These guidelines aim at assisting the different stakeholders (administration, engineering companies, water management bodies, etc.) involved in the implementation of a water reuse programme in a specific area. AQUAREC Handbook on Feasibility Studies for Water Reuse Systems, publicly available, deals with all information
*Corresponding author. Presented at AQUAREC 2006 — Integrated Concepts for Reuse of Upgraded Wastewater, Barcelona, 1–3 February 2006 0011-9164/08/$– See front matter © 2008 Published by Elsevier B.V. doi:10.1016/j.desal.2006.08.023
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needs necessary to successfully face a water reuse project. Background information data collection support, technology options evaluation or environmental impact assessment guidelines are offered in this publication. Furthermore, the assessment methodologies and indicators for social, economic and environmental factors are also provided. Last but not least, cost effectiveness analysis methodologies and technology validation are also addressed. Keywords: Water reuse; Economic; Social; Environmental; Feasibility
1. Introduction 1.1. Main considerations on water reuse Different recent international forums have clearly noted that water will be one of the central issues of the 21st century in the globe, and thus the life of billions of people will depend on its wise management. Water is an essential and basic human need for urban, industrial and agricultural use and has to be considered as a limited resource. Only 1% of the world total water resources are fresh water and in 2025 nearly one-third of the population of developing countries — some 2.7 billion people — will live in regions of severe water scarcity. They will have to reduce the amount of water used in irrigation and transfer it to the domestic, industrial and environmental sectors. Moreover, water pollution by human interference, e.g. by industrial effluents, agricultural pollution or domestic sewage, will increase and the world’s primary water supply will need to increase by 41% to meet the needs of all sectors which will be largely due to the increase in the world population. In this scenario, a unique and viable opportunity to augment traditional water supplies provides water reclamation and reuse, the only solutions to close the loop between water supply and wastewater disposal. Promising is the fact that since many years it is feasible to treat wastewater to a high quality. Hence, wastewater could be regarded as a resource that could be put to beneficial use rather than wasted. Water reuse accomplishes two fundamental functions: the treated effluent is used as a water
resource for beneficial purpose and the effluent is kept out of streams, lakes, and beaches thus reducing pollution of surface water and groundwater. In addition to the economic savings, valuable substances and heat recovery can be achieved by water recycling favouring a zero emission process. One fundamental advantage of water reuse is the fact that in many cases the resource employed is available in the vicinity of its prospective new use, i.e. urban agglomerations and industrial sites. The limiting factor for water reuse can in many circumstances be the quality of the water available linked to the treatment processes (technology) and potential hazards for secondary users. The practise of waste water reuse is increasing greatly within the EU, mostly to alleviate the lack of water resources in certain regions, such as in Southern European countries, but also to protect the environment especially in coastal waters by removing all discharges into fragile receiving waters. In this sense, the full implementation of the Urban Waste Water Treatment Directive (91/ 271/EEC) in Europe will contribute to obtain treated wastewaters of quite high quality amenable for reuse. In fact, Article 12 of the Directive mentions that treated water shall be reused whenever appropriate. However, at present there are no supra-national regulations on wastewater reuse in Europe. Depending on water origin and treatment process, water reuse applications can be divided in seven categories. These categories, in order of significance (number of implemented projects), and their main constraints are shown in Table 1. The
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Table 1 Categories of water reuse and main constraints [1] Wastewater reuse categories
Potential constraints
1. Agricultural irrigation • Crop irrigation • Commercial nurseries 2. Landscape irrigation • Parks • School yards • Freeway medians • Golf courses • Cemeteries • Greenbelts • Residential uses
Surface and groundwater pollution if not properly managed Marketability of crops and public acceptance Effect of water quality, particularly salts, on soil and crops Public health concerns related to pathogens (bacteria, viruses, and parasites) Use area control including buffer zone. High costs for user may result
3. Industrial recycling and reuse • Cooling • Boiler feed • Process water • Heavy construction
Constituents in reclaimed wastewater related to scaling, corrosion, biological growth and fouling Public health concerns, particularly aerosol transmission of pathogens in cooling water
4. Ground water recharge • Ground water replenishment • Salt water intrusion control
Organic chemicals in reclaimed wastewater and their toxicological effects Total dissolved solids, nitrates, and pathogens in reclaimed wastewater
5. Recreational/environmental uses • Lakes and ponds • Marsh enhancement • Stream flow augmentation • Fisheries • Snowmaking
Health concerns of bacteria and viruses Eutrophisation due N and P in receiving water Toxicity to aquatic life
6. Non potable urban uses • Fire protection • Air conditioning • Toilet flushing
Public health concerns on pathogens transmitted by aerosols Effect of the quality on scaling, corrosion, biological growth, and fouling Cross connection
7. Potable reuse • Blending in water supply reservoir • Pipe to pipe water supply
Constituents in reclaimed wastewater, especially trace organic chemicals and their toxicological effects Aesthetics and public acceptance Health concerns about pathogen transmission, particularly viruses
largest application is the irrigation of crops, golf courses and sports fields. Water from recycling systems used in each one of the seven categories should fulfil four criteria: hygienic safety, aesthetics, environmental tolerance as well as technical and economical feasibility. Nevertheless, the potential for water reuse and recycling has not yet been fully exploited in many European areas. A decisive factor to achieve a
higher percentage of water reuse is the establishment of effective incentives, which in many instances will be of either an economic or a regulatory nature. Water reuse has to be considered in the first stages of an Integrated Water Resources Management Project. To examine its economic viability, a careful cost-benefit analysis for the various parties involved needs to be carried out regarding
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mainly technology aspects. But some water reuse implementation projects have failed because some other key factors, such as social awareness or associated ecological effects, were not accounted for. Thus, the consideration of regulatory, economic, technological, social and environmental factors seems essential to successfully accomplish a reclaimed water reuse project. 1.2. Feasibility studies methodology Feasibility studies can contribute to obtain successfully completed water reuse projects. A feasibility study is defined as an evaluation or analysis of the potential impact of a proposed project or program and is conducted to assist decision–makers in determining whether or not to implement a particular project or program. It is based on extensive research on the current practices and the proposed project/program and its impact. Accordingly, it will contain extensive data related to financial and operational impact and will include advantages and disadvantages of both, the current situation and the proposed plan. Within AQUAREC, a water reuse feasibility study methodology — summarised in Fig. 1 — has been developed considering regulatory, economic, technological, social and environmental factors. This methodology is publicly available in AQUAREC Handbook on Feasibility Studies for Water Reuse Systems [2]. The aim of this handbook is to offer a useful methodology to assist the different stakeholders (administration, engineering companies, water management bodies, etc.) involved in the implementation of a water reuse programme in a specific area and to provide the needed tools to address a water reuse feasibility study for a specific purpose. 2. Information collection When facing a feasibility study it is fundamental to count with different reliable data values, indicators or information of very different nature. Some basic records to be collected include:
• Water supply and demand (local and seasonal). • Water and wastewater management agencies in the area. • Regional water and wastewater facilities (in operation and planned). • Water cost and quality requirements. • Environmental setting (climate, geography and topography, water resources –surface and groundwater). • Land use and population (current state and projections). • Structure and location of potential users. • Ecological and hydro-geological boundary conditions. • Water related socio-economic facts (water supply restrictions on domestic, industrial and/or irrigation uses) • Status of public acceptance of water reuse. To obtain this information it is necessary to contact with the main stakeholders (different water-related institutions, organisations and associations) in the evaluated zone such as water and wastewater agencies, regional environmental agencies, councils and regional governments (land and population projections, funding options, etc.), farmers associations, end-users associations, etc. Moreover, different maps (boundaries, location of water and wastewater facilities, location of water sources, zones of land uses, possible users of the reclaimed water and population zones, geological zones, etc.) should also be compiled. The location of the water supply and wastewater facilities is crucial. In addition, the correct identification/location of its users and the reclaimed water flow and quality demands will also be key factors as they will condition the treatment, storage, piping and distribution needs, being one of the most relevant items to consider in the economical evaluation of the proposal. In order to integrate recorded data and maps the utilisation of Geographical Information System (GIS) tools is extremely useful (Fig. 2). Socio-economic facts and other data like water supply restrictions on domestic, industrial and
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EXECUTIVE SUMMARY
BACKGROUND INFORMATION
PROPOSED SYSTEMS
COMPARISON OF THE CURRENT AND PROPOSED SYSTEMS
CONCLUSIONS AND RECOMMENDATIONS
PROPOSED PROJECT SCHEDULE
ANNEXES
Fig. 1. General structure of a water reuse feasibility study [2].
Fig. 2. Dimension image (GIS) of a specific area [2].
• Characteristics of the zone • Integrated water balance of the zone/region/ catchment • Characteristics of the water supply and sanitation • Seasonal variations – past and future trends • Quality standards for effluent and reused water • Potential users of reclaimed water • Literature review • Description of each proposed system (advantages, disadvantages, requirements, basic layout) • Equipment’s needs and costs • Site possibilities • Environmental and sociological studies • Impact on population, industry, agriculture, tourism, hygiene and water quality • Selection of the alternatives • Result of computer network modeling analysis • Summary of probable costs and cost effectiveness analysis • Financial options
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irrigational uses or cost and prices for water supply and sewerage might be compiled too. Furthermore, other aspects such as price of power in the zone, climate and level of incomes of the population should also be recorded as they could probably determine the type of treatment to implement. The data scope should cover a wide period of time (from 20 to at least 5 years) so as to predict and consider the trend of each parameter (rainfall, temperature, water resources, water demand, population, land uses, wastewater quality, water prices and so on). The implementation of a water reuse project will certainly alter existing planning concepts, especially the potable water supply and distribution systems which are usually foreseen for a long time. Moreover, wastewater treatment plants are usually planned to operate for at least 20 years so as the quality of the reclaimed water will depend on the treatment itself these forecasts should be accounted for. Lastly, other civil works such as piping, storage tanks, etc. must be correctly sized to fulfil with the future needs (10–20 years). In summary, the executed projections must be realistic and cover a wide period of time. Status of public acceptance of water reuse is another important issue that needs consideration. In fact, many water reuse projects have not succeeded for not considering social opinion with regard to the project or over estimate the acceptance and needs of the final users. Public acceptance can change depending on the water reuse application. For instance, water reuse for landscape irrigation, agricultural uses and industrial applications are usually well or relatively well accepted whereas reuse for indirect potable uses is not well considered. Moreover educational (unknown effectiveness, potential risks, etc.) and socio-economic considerations (perception of water as an unlimited cheap resource, etc.) and religious issues should also be considered. In order to improve the social acceptance of water reuse, information about its benefits (environmental, economic, etc.) together with a train-
ing session on the key terms (water, wastewater, reclaimed water, water treatment, water quality, etc) should be promoted. Direct information has proved to have a positive influence in users’ willingness and a higher level of income and education are positively correlated with a respondent’s willingness to use recycled water. In any case, cost and risks are usually the main aspects to determine social acceptance.
3. Proposed water reuse options The choice of the right wastewater treatment technology is the most important step in planning a water reuse system because it is the key means of decreasing its potential risk that compiles environmental, technical, social and economical risks as shown in Fig. 3. Amongst the risks linked to reclaimed water use, the possible transmission of infectious diseases by pathogens is the most important concern. Besides, the environmental risk is connected with the contamination amenable to be found in the upgraded wastewater. In summary, the environmental impact assessment (EIA) of a water reuse project may address the following groups of risk: 1. Substantial alteration of land use; 2. Conflict with the land use plans or policies regulations; 3. Adverse impact on wetlands; 4. Affection of endangered species or their habitat; 5. Populations displacement or alteration of existing residential areas; 6. Anthagonistic effects on a flood-plain or important farmlands; 7. Adverse effect on parklands, reserves, or other public lands designated to be of scenic, recreational, archaeological, or historical value; 8. Significant contradictory impact upon ambient air quality, noise levels, surface or groundwater quality or quantity;
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ENVIRONMENT
ENVIRONMENTAL SAFETY
ENGINEERING
ECONOMIC LOSSES
TECHNICAL VIABILITY
TECHNICAL FAILURE
ENVIRONMENTAL FAILURE
RISKS
ECONOMY
ECONOMIC EFFECTIVENESS
SOCIETY
SOCIAL DISRUPTION
SOCIAL EQUITY
Fig. 3. Risks and objectives for sustainable water reuse [3].
9. Substantial adverse impacts on water supply, fish, shellfish, wildlife, and their actual habitats. Accordingly, the fundamental purpose of water treatment is to protect the consumer from pathogens and from impurities in the water that may be injurious or offensive to human health. Where appropriate, treatment should also remove impurities which, although not harmful to human health, may make the water unappealing, damage pipes, plant or other items with which the water may come into contact, or render operation more difficult or costly. Apart from water quality requirements, the applied technology or technologies to provide with reclaimed water will vary depending on many other factors such as economical aspects (treatment cost, economical level of the population and richness of the country), land requirements, power price, climate conditions, distances among the wastewater production place and water reuse site, size of the plant, flow design, flow seasonality, previously implemented systems and so on.
In Table 2 an overview of the different unit processes yielding reclaimed water for different applications is given. In summary, combining the various processes and operations it is now possible to produce high quality water from municipal wastewater for any reuse application. However, the feasibility of such wastewater reuse program will depend mainly on public acceptance and cost.
4. Water reuse costs and financing A common misconception in planning for water reclamation and reuse is that reclaimed water represents a low-cost new water supply. This assumption is generally true only when water reclamation facilities are conveniently located near large agricultural or industrial users and when no additional treatment is required beyond the existing water pollution control facilities from which reclaimed water is delivered. The conveyance and distribution systems for reclaimed water represent the principal cost of most water reuse projects.
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Table 2 Overview of main unit processes and operations used in water reclamation [1] Process Solid/liquid separation Sedimentation
Filtration
Description
Application
Removal of particulate matter, chemical flocs and precipitates from suspension by gravity settling. Particle removal by passing water through sand or other porous medium.
Removal of particles > 30 µm from turbid water.
Biological treatment Aerobic biological treatment Biological metabolism by microorganisms in an aeration basin or biofilm process Ponds up to one metre in depth for mixing Oxidation pond and sunlight penetration. Biological nutrient removal
Waste stabilisation ponds
Disinfection
Advanced treatment Activated carbon Air stripping Ion exchange
Chemical coagulation and precipitation
Lime treatment
Membrane filtration Reverse osmosis
Combination of aerobic, anoxic, and anaerobic processes to optimise conversion of organic and ammonia nitrogen to molecular nitrogen (N2) and phosphorus removal. Pond system consisting of anaerobic, facultative and maturation ponds linked in series to increase retention time. The inactivation of pathogenic organisms using oxidizing chemicals, ultraviolet light, caustic chemicals, heat, or physical separation processes (e.g. membranes). Contaminants are physically adsorbed onto the activated carbon surface. Transfer of ammonia and other volatile components from water to air. Exchange of ions between an exchange resin and water using a flow through reactor.
Removal of particles > 3 µm from turbid water. Frequently used after sedimentation or coagulation/flocculation Removal of dissolved and suspended organic matter from wastewater. Reduction of suspended solids, BOD, pathogenic bacteria, and ammonia from wastewater. Reduction of nutrient content in reclaimed water.
Reduction of suspended solids, BOD, pathogenic bacteria, and ammonia from wastewater. Facilitates water reuse for irrigation and aquaculture. Protection of public health by removal of pathogenic organisms.
Removal of hydrophobic organic compounds Removal of ammonia and some volatile organics from water Effective for removal of cations such as calcium, magnesium, iron, ammonium, and anions such as nitrate Formation of phosphorus precipitates and flocculation of particles for removal by sedimentation and filtration.
Use of aluminium or iron salts, polyelectrolytes, and/or ozone to promote destabilization of colloidal particles from reclaimed water and precipitation of phosphorus. Use of lime to precipitate cations and metals Used to reduce scale-forming potential of water, precipitate phosphorus, and modify from solution. pH. Removal of particles and microorganisms Micro-, nano-, and ultrafiltration from water. Removal of dissolved salts and minerals Membrane system to separate ions from solution based on reversing osmotic pressure from solution; also effective for pathogen removal. differentials.
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A recent study in California indicates that the amortised cost of reclaimed water is about 0.44 €/m3, excluding operation and maintenance costs. This reclaimed water is normally too expensive for traditional agricultural irrigation in the United States and most other countries; only landscape irrigation and other urban applications can afford to pay for the water. The different water reuse options should be compared with the conventional non-reuse alternative. In most cases there is not a single most suitable option. Two or more different types of treatments and water reuse applications are often recommended. The probable cost for implementing a water reuse alternative requires the investigation of four primary cost components: • Distribution of the reclaimed water • Additional treatment at the wastewater plant, if required, above the requirements necessary to achieve water quality standards for discharge of the effluent • Storage systems and pressure maintenance of the regenerated water, and • Water quality monitoring and additional administration for maintaining two water systems
Investment costs account for 45–75% of the total cost of a water reuse project [1]. Comparison of reclaimed water costs with a similar compilation of costs for a freshwater supply system provides a measure of cost-effectiveness of a reuse project. The cost effectiveness of reuse projects is directly related to the volume of reclaimed water used: the more water utilised, the more cost-effective the project. In this sense irrigation generally provides the highest potential of water reuse. However, reuse costs should also integrate external costs of an environmental or social nature [4,5] usually not considered. Accordingly, funding and management of a water reuse system is a key element for a feasible
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implementation. The funding mechanisms can be split in two related categories: 1. Financing of up-front costs (i.e. initial capital investment) 2. Financing of ongoing operating costs (i.e. revenue programmes during the operation to cover debt service and operation and maintenance costs). The EU does not have specific subsidies to encourage water reuse. Basically there are six European programmes or organisations that are likely to finance water recycling projects: European Investment Bank (EIB), Short and Mediumterm Priority Environmental Action Programme (SMAP), Financial Instrument for the Environment (LIFE), Community Initiative of the European Regional Development Fund (especially, Urban II), Structural Funds (FEDER) and Cohesion Fund. Alternatively, the Interreg Programme is also available.
5. Social, environmental and economical impact assessment Using reclaimed water in place of fresh water for existing uses can free up existing water supply system capacity to cater for new water needs. This results in savings in the cost of developing new water sources, water transfers and treatment and distribution systems. It can also result in significant improvements in downstream river water quality. The different socio-environmental and economical benefits resulting from water conservation and reuse include [6]: (a) agriculture benefits such as: (i) reduced diversion costs, (ii) value of a secure “drought proof” supply of reclaimed water, (iii) increased farm production, and (iv) value of reclaimed water nutrients, i.e. savings in fertiliser applications and pesticides;
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(b) urban water supply benefits such as: (i) savings in the capital cost of diversion structures, drought storage, transfer systems and water treatment and (ii) savings in distribution, operation and maintenance costs including pumping energy, and treatment chemicals; (c) urban wastewater benefits such as: (i) savings in discharge pump stations and pipelines (ii) savings in treatment and nutrient removal costs required for discharge to sensitive waters (iii) savings in operation and maintenance costs (heat recovery, chemicals); (d) environmental water quality benefits such as: (i) reduction in freshwater diversions – more river flow for downstream users – better downstream water quality (ii) reduction in pollutant discharges (iii) better downstream water quality – reduced environmental impact and improved river aesthetics – reduced impacts on fisheries and aquatic life – improved public health for downstream users – lower water treatment costs for downstream users – improved recreational values of waterways (iv) reduction of the potential salinity intrusion risk in groundwater aquifers (v) improvement of the ecosystem and increase of the fauna and flora species due to the creation of new recreational zones, parks, gardens and green areas (vi) improvement of the quality of the seawater and beaches e) increase in the tourist activity due to the good quality of the seawater and beaches and quantity of golf courses, sport fields, swimming pools, recreational zones, etc. f) decrease in raw materials, reagents, and water
or heat consumption due to water recycling in the industry. Decrease in the environmental penalties that these industries should pay for the wastewater discharge. g) increase of the quality of life of the population due to (i) the increase of recreational zones, parks, gardens, sport fields, golf courses, etc. (ii) the improvement of the sanitary and health quality of the water (decrease of the diseases related to the water), (iii) the improvement of the environment (iv) the decrease or restrain in the water price due to the non needed water diversion infrastructures (v) the increase of the employment due to the creation of new jobs direct and indirectly related with water reuse. New employments related with the increase of the tourist or agricultural activity in the zone, maintenance of new green areas (parks, gardens and recreational zones) and more directly connected to the operation and maintenance of the wastewater treatment plants, water engineering companies, suppliers of systems, equipment and chemicals for wastewater treatment and water reuse. Within AQUAREC, 25 different indicators have been proposed to evaluate reclaimed water reuse-related social (6), economical (4) and environmental (15) aspects. These indicators can be further analysed through a semi-quantitative assessment (especially for social and environmental indicators) by associating each one of them to a range of colours or values (Table 3) and for which technical expertise in the indicator evaluation is needed. Furthermore, a tentative reference assessment scale must be established to measure the feasibility of each project. It is assumed beforehand that all indicators have identical weight, which is a simplistic approach. Alternatively, the proposed indicators can be
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book on Feasibility Studies for Water Reuse Systems that can be downloaded from www.acquarec. org website. This work is part of the AQUAREC project Integrated Concepts for Reuse of Upgraded Wastewater (EVK1-CT-2002-00130) funded by the EESD Programme of the European Commission.
Table 3 Classification of impacts of water reuse indicators using semi-quantitative assessment [2]
Range (Produced impact)
Value
Very negative Slightly negative No change Slightly positive Very positive
–2 –1 0 1 2
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References [1] T. Asano, ed., Wastewater Reclamation and Reuse, Technomic Publishing Inc., Lancaster, PA, 1998. [2] AQUAREC, ed., Handbook on Feasibility Studies for Water Reuse Systems. [3] J. Ganoulis, Evaluating alternative strategies for wastewater recycling and reuse in the Mediterranean area. Wat. Sci. Tech.: Water Supply, 3(4) (2003) 11–19. [4] G. Louis and M. Siriwanada, A procedure for calculating the full cost of drinking water. CEWorld-a virtual, American Society of Civil Engineers, 2001, www.ceworld.org. [5] S. Renzetti, Full Cost Accounting for Water Supply and Sewage Treatment: A Case Study of the Niagara Region, Canada. World Bank’s Resources Management Group on Economic Instruments, 2003, www.worldbank.org. [6] J. Anderson, The environmental benefits of water recycling and reuse. Wat. Sci. Tech.: Water Supply, 3(4) (2003) 1–10.
used in a quantitative assessment in which the weight of each indicator is implicitly included in its individual reference scale, like in Table 4 where the social indicator number 2 (quality of life) is ranked regarding its compliance against guiding values of the Bathing Water Directive (100% = full compliance). This assessment should be completed with community and stakeholder consultation to prove public acceptance of the water reuse project proposal. 6. Final comments and acknowledgements The information provided in this paper is more profusely dealt with within AQUAREC Hand-
Table 4 Example of score rating for water reuse indicators using quantitative assessment [2]
Score
0
1
2
3
4
5
6
7
8
9
10
SI2
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%