Viability of increasing the tariff of freshwater for irrigation as a tool to stimulate wastewater reuse in the MENA region.

Despite water scarcity and high agricultural water demand in the Middle East and North Africa region, substantial proportions of treated wastewater are discharged into the environment and seas without proper utilization. All countries of the region, low pricing of reclaimed wastewater is a common tool to make reuse attractive. However, low pricing of reclaimed wastewater is ineffectual due to farmers' access to freshwater for irrigation at low tariff. Therefore, increasing the prices of freshwater in such a way that does not jeopardize feasibility of agriculture would promote irrigation with reclaimed wastewater even at increased prices. On one hand, it increases the gap between the price of freshwater and that of reclaimed wastewater, making the later more attractive. On the other hand, it would be used as a financial resource for funding the investment costs of the infrastructure needed for conveyance and distribution of reclaimed wastewater. This paper studies the viability of increasing the prices of freshwater and reclaimed wastewater. The results show that irrigation with reclaimed wastewater even for restricted irrigation can be as profitable as, and sometimes better than, freshwater irrigation. Some of the permitted crops such as fruit trees can be more profitable than vegetables. Thus, it appears that the level of knowledge farmers and others on the benefits of reclaimed wastewater is still limited.     

Linking environmental and economic sustainability in establishing standards for wastewater re-use in Israel.

Israel is one of the world's leaders in agricultural re-use of wastewater, currently re-using over 60% of produced wastewater. The effects of arid climate, intensive irrigated agriculture and limited water resources make re-use necessary to conserve fresh water for domestic use. Quality standards for wastewater re-use are needed to protect public health and prevent environmental and agricultural damage. This paper examines the environmental and economic sustainability of the proposed upgrade of wastewater quality standards. A tertiary treatment standard was proposed, but has not been approved due to objections from local authorities and farmers. An upgrade will require higher treatment costs, which will be divided between farmers and local authorities through the pricing of the wastewater. Farmers oppose the upgrade because they will not be able to pay higher prices for wastewater, which they use to irrigate low-profit crops. If the price is too high, these farmers may be forced out of business and a substantial reduction in cultivated lands may result. If the price is too low, the poorer local authorities may not be able to comply with the standards, and may discharge improperly treated wastewater, causing environmental damage. A successful policy balances the needs for environmental protection with the economic realities of farmers and local authorities and may require compensation for local authorities or farmers in order to achieve maximum environmental protection.     

Integrated Resource Planning for Water and Wastewater

Abstract

This paper describes the use of integrated resource planning for water and wastewater service provision by a major urban water utility. This methodology aims to meet the water and sewerage needs of the community at the least cost and includes an explicit analysis of the costs and benefits of measures that reduce the demand for water and the discharge of wastewater effluent. It therefore requires disaggregation of the demand for water into end-uses and a consideration of the linkages between the water supply and sewerage components of the business. This approach has significant advantages in economic, environmental, and social terms. The case study results indicate that significant investments in water efficiency programs are justified on economic grounds, particularly where augmentation of water and sewerage infrastructure is planned. Three studies undertaken as part of Sydney Water's efforts to integrate supply- and demand-side planning are described in this paper: first, a major integrated resource planning exercise designed to reduce demand for water by up to 35 percent, costing more than AU$25 million; second, a case study in a series of small towns where the benefits arise from reducing the capacity of sewage treatment plants by reducing wastewater flow; and third, in a major industrial region where water efficiency measures integrated with reuse measures reduce overall costs.     

A Decision Support Methodology for Integrated Urban Water Management in Remote Settlements

This paper describes a decision support methodology for the selection of a wastewater treatment system based on integrated urban water management principles for a remote settlement with failing septic systems. Thirty-two service and treatment technologies options were considered, these included: (i) conventional gravity sewerage, (ii) common effluent drainage, (iii) community sewage treatment plant based on various technology options (lagoon treatment, Living Machine®, sequencing batch reactor, membrane biological reactor, rotating biological contactor, recirculating textile filter, extended aeration) with and without urine separation, greywater diversion or treatment and reuse at household scale. The options were assessed using a framework that considered technical, economic, environmental and social factors relevant to the local community and associated stakeholders (water utility, government agencies) and tools such as engineering design, life cycle assessment and multi-criteria analysis for evaluation of overall sustainability. Adoption of a systems approach allowed the identification of benefits and trade-offs among stakeholders creating opportunities for adoption of more innovative treatment options and maximisation of the sustainability of the service. The treatment option that maximised the social, environmental and economic benefits for the settlement consisted of individual households adopting greywater treatment, storage and reuse, urine separation and a community wastewater treatment plant with recirculating textile filter technology. This solution provided the required sanitation, increased the sources of water supply to residents, satisfied environmental regulator requirements, minimised nitrogen discharge to waterways and provided an option for beneficial reuse of urine for neighbouring farmers at a cost and management needs acceptable to the water utility.     

Wastewater Irrigation-Economic Concerns Regarding Beneficiary and Hazardous Effects of Nutrients

The optimal wastewater treatment level is affected by costs, hazards and benefits. Lowering the wastewater treatment level decreases fertilization costs because of the increased levels of available nutrients left in the water, and irrigation costs decrease if water prices reflect the lower treatment costs. Agricultural yields and/or prices may decrease according to differences between levels of nutrients needed by crops and those available in wastewater. The present article focuses on determination of monthly optimal treatment levels and of the mix of crops calculated to maximize agricultural incomes, according to farmers' point of view. It does not reflect the national point-view focusing on maximization of net national benefits considering also environmental hazards. The methodology appears in Haruvy (1994) and application will be presented in another article (Haruvy et al., 1999).     

A knowledge management methodology for the integrated assessment of WWTP configurations during conceptual design

The current complexity involved in wastewater management projects is arising as the XXI century sets new challenges leading towards a more integrated plant design. In this context, the growing number of innovative technologies, stricter legislation and the development of new methodological approaches make it difficult to design appropriate flow schemes for new wastewater projects. Thus, new tools are needed for the wastewater treatment plant (WWTP) conceptual design using integrated assessment methods in order to include different types of objectives at the same time i.e. environmental, economical, technical, and legal. Previous experiences used the decision support system (DSS) methodology to handle the specific issues related to wastewater management, for example, the design of treatment facilities for small communities. However, tools developed for addressing the whole treatment process independently of the plant size, capable of integrating knowledge from many different areas, including both conventional and innovative technologies are not available. Therefore, the aim of this paper is to present and describe an innovative knowledge-based methodology that handles the conceptual design of WWTP process flow-diagrams (PFDs), satisfying a vast number of different criteria. This global approach is based on a hierarchy of decisions that uses the information contained in knowledge bases (KBs) with the aim of automating the generation of suitable WWTP configurations for a specific scenario. Expert interviews, legislation, specialized literature and engineering experience have been integrated within the different KBs, which indeed constitute one of the main highlights of this work. Therefore, the methodology is presented as a valuable tool which provides customized PFD for each specific case, taking into account process unit interactions and the user specified requirements and objectives.     

Wastewater reclamation through a combination of natural systems (infiltration-percolation and constructed wetlands): a solution for small communities.

The decision on technologies used for reclaiming wastewater appears as important as a consequence of the implications on the economic, environmental and health conditions of societies. The problem arises when deciding how to deal with wastewater in small communities, because the costs of implementing and operating small, intensive wastewater treatment plants are unacceptable and can lead to financing and operation problems. Extensive treatment systems can be a good solution, where space is available. This paper presents the combination of two soft technologies (infiltration-percolation and constructed wetlands) to treat and reclaim wastewater. The obtained results show that the infiltration-percolation effluent presents a quality enough to be reused for irrigation of industrial crops, nurseries, fodder, cereals and oleaginous seeds, ornamental flower production; industrial cooling; impoundments, water bodies, and streams for recreational use in which the public's contact with the water is not permitted; and irrigation of forested areas, landscape areas and restricted access areas. Moreover, the combination of infiltration-percolation and constructed wetlands increases the list of final reclamation to the following: irrigation of pasture for milk or meat animals, crops for canning industry, crops not raw-consumed, fruit trees except by sprinkling, aquaculture; and aquifer recharge by localised percolation through the soil.     

Comparison between ozonation and the OSA process: analysis of excess sludge reduction and biomass activity in two different pilot plants

The excess biomass produced during biological treatment of municipal wastewater represents a major issue worldwide, as its disposal implies environmental, economic and social impacts. Therefore, there has been a growing interest in developing technologies to reduce sludge production. The main proposed strategies can be categorized according to the place inside the wastewater treatment plant (WWTP) where the reduction takes place. In particular, sludge minimization can be achieved in the wastewater line as well as in the sludge line. This paper presents the results of two pilot scale systems, to evaluate their feasibility for sludge reduction and to understand their effect on biomass activity: (1) a pilot plant with an ozone contactor in the return activated sludge (RAS) stream for the exposition of sludge to a low ozone dosage; and (2) an oxic-settling-anaerobic (OSA) process with high retention time in the anaerobic sludge holding tank have been studied. The results showed that both technologies enabled significant excess sludge reduction but produced a slight decrease of biomass respiratory activity.     

Estimating costs and benefits of advanced control for wastewater treatment plants--the MAgIC methodology.

This paper discusses a methodology to estimate the costs and benefits of advanced control for wastewater treatment plants. The methodology has been applied to four wastewater treatment plants, representing four standard types of plants built in Flanders, Belgium. The paper outlines the methodology and illustrated results from one of the four design cases. General results are shown and contrasted with full-scale experience. The methodology appears to give realistic results and will be used for further refinement of default control algorithms for certain types of plants. A preliminary analysis indicates that on-line control can become cost-effective for plant sizes above 50,000 population equivalents.     

Effluent standards for developing countries: combining the technology- and water quality-based approach.

It is a challenge for developing countries to realize socio-economical development without impairing water resources in an unacceptable way. A possible means for controlling water pollution is through defining, applying and enforcing effluent standards for wastewater discharges. However, in many developing countries the definition of effluent standards is still poor. They are either too stringent because they are based on standards from developed countries, or too relaxed and therefore they do not guarantee the safe intended uses of water. In order to define an approach for setting effluent standards that suits the needs and means of developing counties, water quality management practices in the USA, the EU, the New Independent States (NIS) and the Philippines were analyzed and compared. Four criteria (protection of the environment, technical viability, economic feasibility and institutional capacity requirements) were used to assess the suitability of these practices for developing countries. It is concluded that a combined approach that is based on best available technology not entailing excessive costs and environmental quality standards is the best way to define effluent standards that restrict water pollution against affordable costs.     

Economic Assessment of Best Management Practices in the Mara River Basin: Toward Implementing Payment for Watershed Services

The Mara River in East Africa is currently experiencing poor water quality and increased fluctuations in seasonal flow. Improved water quality will require upstream farmers and foresters to adopt Best Management Practices (BMPs), which might cost them considerably. This study proposes a Payment for Watershed Services (PWS) mechanism. This is a market-based approach, whereby downstream water users would pay upstream watershed service providers towards the costs of BMPs implementation. This study analyzes the technical feasibility and economic viability of adapting selected BMPs and provides cost estimates of a PWS program. Using three criteria of water quality improvement, economic feasibility, and technical suitability, a detailed economic opportunity cost analysis revealed that farmers would indeed incur economic losses for all BMPs except no-till farming. We also developed a multi-criteria (demographic and environmental) methodology for identifying land areas to be placed under BMPs. More than 122,000 ha of land would require BMPs, including a moratorium on agriculture inside the Mau Forest Complex. The initial per hectare opportunity costs across the five highest ranked BMPs ranged from US$ 272 to US$ 926. Using these cost estimates, the paper draws some valuable policy and management insights on how to finance BMP implementation.     

Welfare Improvisation from the Receiving Waters of Urban Wastewater Systems in the Context of the Water Framework Directive

The compliance of wastewater authorities with the Water Framework Directive (WFD, 2000/60/EC) although may highly contribute to a “good” ecological status in aquatic ecosystems, is alleged to require disproportionally high costs in relevance to the anticipated benefits. This is mainly due to the limited yet research in the assessment of the economic welfare derived by the compliance with the WFD. In this light, the direct and indirect economic benefits emerged by the attaining of WFD are investigated. The wastewater treatment plant of Athens (Greece) is demonstrated as a comprehensive pilot case.     

Energy-saving wastewater treatment systems: formulation of cost functions.

Natural interactions between water, soil, atmosphere, plants and microorganisms include physical, chemical and biological processes with decontaminating capacities. Natural or energy-saving wastewater treatment systems utilize these processes and thereby enable a sustainable management in the field of wastewater treatment, offering low investment and operation costs, little or no energy consumption, little and low-skill labor requirements, good landscape integration and excellent feasibility for small settlements, especially when remote from centralized sewer systems. The objective of this work is the development of cost functions for investment and operation of energy-saving wastewater treatment technologies. Cost functions are essential for making cost estimations based on a very reduced number of variables. The latter are easily identified and quantified and have a direct bearing on the costs in question. The formulated investment and operation cost functions follow a power law, and the costs decrease with the increase of the population served. The different energy-saving wastewater treatment systems serving small population settlements, between 50 p.e. and 250 p.e., present associated investment costs varying from 400 Euro/p.e. to 200 Euro/p.e. and annual operation costs in the range of 70 Euro/p.e. to 20 Euro/p.e., respectively.     

Technical and economic evaluation of the conjunctive use of surface and groundwater in the Campaspe Valley,north-central Victoria,Australia

This paper describes a technical and feasibility study of increasing groundwater usage to supplement surface water use in the Campaspe Valley in south-eastern Australia. An integrated model which simulates the surface and groundwater processes, as well as the interactions between the processes, is used to determine the sustainable long-term groundwater pumping yields. The model also provides estimates of groundwater fluxes for various management options of increasing groundwater usage. These estimates are used to assist an economic analysis to determine the relative merits of various options for the conjunctive use of surface and groundwater resources. The pumping costs, value of water and tangible salinity benefits from lowering high water-tables and reducing salt load are considered in the economic analysis. The methodology is also relevant for other studies looking into the conjunctive use of surface and groundwater resources throughout the Murray Basin and elsewhere.     

An Inexact Chance-constrained Quadratic Programming Model for Stream Water Quality Management

Water quality management is complicated with a variety of uncertainties and nonlinearities. This leads to difficulties in formulating and solving the resulting inexact nonlinear optimization problems. In this study, an inexact chance-constrained quadratic programming (ICCQP) model was developed for stream water quality management. A multi-segment stream water quality (MSWQ) simulation model was provided for establishing the relationship between environmental responses and pollution-control actions. The relationship was described by transformation matrices and vectors that could be used directly in a multi-point-source waste reduction (MWR) optimization model as water-quality constraints. The interval quadratic polynomials were employed to reflect the nonlinearities and uncertainties associated with wastewater treatment costs. Uncertainties associated with the water-quality parameters were projected into the transformation matrices and vectors through Monte Carlo simulation. Uncertainties derived from water quality standards were characterized as random variables with normal probability distributions. The proposed ICCQP model was applied to a water quality management problem in the Changsha section of the Xiangjiang River in China. The results demonstrated that the proposed optimization model could effectively communicate uncertainties into the optimization process, and generate inexact solutions containing a spectrum of wastewater treatment options. Decision alternatives could then be obtained by adjusting different combinations of the decision variables within their solution intervals. Solutions from the ICCQP model could be used to analyze tradeoffs between the wastewater treatment cost and system-failure risk due to inherent uncertainties. The results are valuable for supporting decision makers in seeking cost-effective water management strategies.     

Strategic options for sustainable water management at new developments: the application of a simulation model to explore potential water savings.

Research on appropriate technologies and infrastructures to support water reuse has progressed rapidly over recent decades and there are now a wide range of source--treatment--reuse options for planners to choose from. Although the economics of water reuse schemes favours application to new developments rather than retrofit projects, there are few studies which have sought to address strategic option selection issues for large developments. The potential advantages of using treatment and reuse systems in new developments require an understanding of the relationships between a wide variety of social, environmental, technological, and operational factors. The operational effectiveness and economic efficiency of specific technology choices will vary as a function of network configuration, wastewater characteristics, how different technologies respond to dynamic loading (variability of feed strength and flow) and potential spiking, as well as equipment reliability, climate and household behaviour. Using a commercially available software package, the study reports the design and implementation of a low resolution simulation tool to explore sustainable water management options for a live case study site in the south of England (a peri-urban development of 4,500 new homes) with particular reference to opportunities for rainwater harvesting, and water reuse.     

Incorporating Environmental Value and Externality in Project Evaluation as a Sustainability Indicator to evaluate Bangladesh Water Development

A major difficulty of conventional cost benefit analysis is that it will allow choosing an alternative among others only on the criterion of economic efficiency: that the selected project or activity has been proven to produce economic benefits over costs for the period of the project. An analysis of this kind generally does not create a problem if the costs and benefits series are easy to quantify and clearly identifiable. However, almost all projects linked with the environment are clear exceptions to this category. Many environmental projects are facing a difficulty of evaluating the success based on economic efficiency due to two reasons: (a) environmental benefits are difficult to quantify and (b) environmental interactions that will cause severe externalities are difficult to predict. The main objective of this paper is to suggest a new method that can be used to overcome such difficulties in environmental projects. Data used in this analysis will demonstrate a practical approach to evaluate environmental projects. The evaluation proposed is different to traditional analysis in that it has been based on a large programme of primary research and has included efforts to achieve a consensus of all stakeholders, including those directly involved in project implementation.     

A knowledge-based control system for air-scour optimisation in membrane bioreactors

Although membrane bioreactors (MBRs) technology is still a growing sector, its progressive implementation all over the world, together with great technical achievements, has allowed it to reach a mature degree, just comparable to other more conventional wastewater treatment technologies. With current energy requirements around 0.6-1.1 kWh/m3 of treated wastewater and investment costs similar to conventional treatment plants, main market niche for MBRs can be areas with very high restrictive discharge limits, where treatment plants have to be compact or where water reuse is necessary. Operational costs are higher than for conventional treatments; consequently there is still a need and possibilities for energy saving and optimisation. This paper presents the development of a knowledge-based decision support system (DSS) for the integrated operation and remote control of the biological and physical (filtration and backwashing or relaxation) processes in MBRs. The core of the DSS is a knowledge-based control module for air-scour consumption automation and energy consumption minimisation.     

江南水乡区域合理水价模式探讨——以浙江省为例

以浙江省为例,从分析水价的现状入手,提出了现行水价中存在的主要问题,通过对水价组成及执行机制的阐述,以及政府投资、污水综合利用和排污权交易三个方面与环境水价的关系分析,对建立江南水乡区域合理水价模式提出了建议:实行以污水处理费为保证的排污权交易制度,同时逐步减少政府对污水处理厂建设、运营的投资,同时加大污水回用力度,着重从环境水价等机制上形成合理的水价模式。     

A New Integrated MADM Technique Combined with ANP,FTOPSIS and Fuzzy Max-Min Set Method for Evaluating Water Transfer Projects

In sustainable water resources management, it is essential to rank inter-basin water transfer projects. This task is difficult due to many different conflict criteria, complex relations among criteria and various judgments of decision makers. In this paper, an integrated multiple attribute group decision making method consists of ANP (Analytical Network Process), fuzzy TOPSIS and fuzzy max-min set methods is proposed for evaluating water transfer projects. A set of over 60 criteria in social, environmental and economic sectors are used for ranking four water transfer projects in Karun River based on three decision maker judgments. A key novelty of the proposed methodology is its ability to model both complex relations among different criteria in water management and the influence of decision maker judgments’ weights on the final ranking in group decision making problem. The procedure starts by obtaining the priority of water transfer projects and the weight of each decision maker judgments by employing ANP and fuzzy TOPSIS, respectively. These weights are used as inputs in the fuzzy max-min set method. Then the effects of decision maker weights on the final ranking are determined in fuzzy environment. Finally, the sensitivity analysis of decision makers’ weights has been conducted. The results show that the proposed method is an effective tool for group decision making problems by considering different criteria and decision makers’ weights.