Preventive maintenance versus cost of repairs in asset management: An efficiency analysis in wastewater treatment plants

Abstract The operation and management of Wastewater Treatment Plants (WWTPs) is of paramount importance to guarantee the sustainability of water resources. Just like any other production process, wastewater treatment process involves different costs, such as: energy, personnel, maintenance and reagents. Regarding maintenance costs, they have become an issue of great concern to many operators in the last years. Maintaining the facilities in good condition ensures the proper performance of these infrastructures and reduces the risk of failures. It should be known that equipment breakdowns imply an increase in operating costs, with a high risk of generating an environmental damage due to the m…

Development and application of the Hicks-Moorsteen productivity index for the total factor productivity assessment of wastewater treatment plants

Abstract The assessment of the productivity change in wastewater treatment plants is essential to improve performance and reduce operational costs. Several indices are available to compute unit productivity, however some assessments are more reliable than others. In the absence of price data, the Malmquist productivity index is the most commonly applied; but it does not maintain total factor productivity properties under variable returns to scale technology. Hence, Malmquist productivity index is not a suitable index to compute total factor productivity change in wastewater treatment plants. The present study served to overcome such limitations by calculating, for the first time, total fact…

Tariffs and efficient performance by water suppliers: an empirical approach

Water leaks are an environmental and sustainable issue as well as an economic issue. The objective of this paper is to analyse the efficiency of a sample of Spanish urban water systems by considering water leaks in a network as undesirable outputs. Data envelopment analysis (DEA), an analytical benchmarking methodology, is used to calculate technical and economic efficiency. We also discuss the possible relationship between efficiency and tariffs charged to users. Results show that the possibilities for reducing water leaks in networks are high, thus demonstrating that there is room for savings from an economic and environmental point of view. The assessment of efficiency performance could …

Economic feasibility study for new technological alternatives in wastewater treatment processes: a review

The concept of sustainability involves the integration of economic, environmental, and social aspects and this also applies in the field of wastewater treatment. Economic feasibility studies are a key tool for selecting the most appropriate option from a set of technological proposals. Moreover, these studies are needed to assess the viability of transferring new technologies from pilot-scale to full-scale. In traditional economic feasibility studies, the benefits that have no market price, such as environmental benefits, are not considered and are therefore underestimated. To overcome this limitation, we propose a new methodology to assess the economic viability of wastewater treatment tec…

Business Models and Economic Approaches for Recovering Energy from Wastewater and Fecal Sludge

Universal access to water, sanitation and energy services are key challenges in low income countries. The conventional model of providing water, sanitation and waste disposal as a social service is no longer viable because national authorities lack financial and human resources for operation and maintenance and for addressing the sanitation needs locally. Human excreta and wastewater represent resources that can be used to generate new income and support livelihoods through use as a source of energy. The reduction, removal and reuse of wastes must become financially feasible and economically profitable and yield high returns. This requires innovative and sustainable business models and fina…

Operational Indicators to Manage the Replacement of Electromechanical Equipment in Wastewater Treatment Facilities

Optimal management is usually at the top of the concerns in the context of water infrastructures. In the specific domain of wastewater treatment plants (WWTPs), European Directive 91/271 established the need of implementing a biological treatment of wastewater leading to an intensive construction of WWTPs in several European countries, which now present important problems of maintenance. These facilities are composed of different types of assets, which should be managed efficiently in order to optimize the performance of the processes as well as the maintenance and replacement costs of the equipment. In fact, the deterioration of these assets increases the operational risk and endangers th…

Productivity growth of wastewater treatment plants – accounting for environmental impacts: a Malmquist-Luenberger index approach

As the number of wastewater treatment plants (WWTPs) has increased, the economic considerations associated with their management have become more relevant. Measuring the productivity of WWTPs allows the best practice to be identified and resource use to be optimized. Previous studies assessing the productivity change of WWTPs have ignored undesirable outputs; thus, wastewater treatment was considered to be free of environmental impacts. To overcome this limitation and for the first time, we assessed the productivity growth of a sample of Spanish WWTPs, while also accounting for the emission of greenhouse gases and sludge production. The Malmquist-Luenberger productivity index (MLPI) and its…

Cost-effectiveness analysis of sewer mining versus centralized wastewater treatment: Case study of the Arga river basin, Spain

ABSTRACT:In the context of the EU Water Framework Directive, a Cost-Effectiveness Analysis (CEA) was performed to compare centralized and decentralized wastewater treatment strategies aimed to improve the ecological status of a Spanish river. The implementation of several hybrid membrane bioreactors within the urban framework for sewer mining (SM) was compared with the more common wastewater treatment plant enlargement option. The assessment ranked 6 alternatives based on 12 potential scenarios, aimed at narrowing the uncertainty of the CEA. The cost analysis illustrated that SM is the most expensive option regarding both investment and operation and maintenance costs. However, the effectiv…

Pricing for Reclaimed Water in Valencia, Spain: Externalities and Cost Recovery

The cost of reclaimed water and the tariffs paid by water users illustrate that the principle of cost recovery is not met in the majority of water reuse projects. However, such projects may also generate positive externalities, contributing to improved welfare of the entire society. This chapter describes the case of the Valencia region of Spain, referring to agreements among water stakeholders. It also includes a proposal of pricing for reclaimed water to be implemented in this area as a pilot case in order to develop a framework for costs and financial, institutional, and social arrangements for water reuse projects. A two-part tariff with a combination of a decreasing and increasing rate…

Assessment of wastewater treatment plant design for small communities: Environmental and economic aspects

The preliminary design and economic assessment of small wastewater treatment plants (less than 2000 population equivalent) are issues of particular interest since wastewaters from most of these agglomerations are not covered yet. This work aims to assess nine different technologies set-up for the secondary treatment in such type of facilities embracing both economic and environmental parameters. The main novelty of this work is the combination of an innovative environmental decision support system (EDSS) with a pioneer approach based on the inclusion of the environmental benefits derived from wastewater treatment. The integration of methodologies based on cost-benefit analysis tools with th…

The Quantification of Non-Action Costs as an Incentive to Address Water Pollution Problems

Diffuse pollution is one type of pollution generated by agricultural, livestock, and urban runoff that is responsible for surface and groundwater pollution. As a result, the exposed population develops different diseases that affect their short, medium, and long-term quality of life. Researchers need to be able to assess the loss of quality of life in monetary terms to include this social impact in decision-making processes. Specifically, if no measure is implemented to correct the situation, these costs can be considered as the non-action costs of the social impact of water pollution. This study assesses the importance of measuring healthcare costs as a proxy for non-action costs for the e…

A data analysis approach to evaluate the impact of the capacity utilization on the energy consumption of wastewater treatment plants

Abstract The reduction of energy consumption in Waste Water Treatment Plants (WWTPs) is a challenge for the scientific community and for the public authorities. A source of excessive energy cost is the mismatching between operational and design inflow (i.e. capacity utilization): this issue is very relevant above all in areas with high demographic seasonality. Consequently, it is really important to have operational decision criteria to evaluate the impact of a low capacity utilization on energy consumption. In order to provide the scientific community and the plant managers with an adequate criterion, we propose a user-friendly methodology to identify critical conditions of capacity utiliz…

Environmental Benefits of Wastewater Treatment: An Economic Valuation

The need of economic research into the design and implementation of policies for the efficient management of water resources has been emphasized by the European Water Framework Directive (Directive 2000/60/UE). The efficient implementation of policies to prevent the degradation and depletion of water resources requires determining their value in social and economic terms and incorporating this information into the decision-making process. A process of wastewater treatment has many associated environmental benefits. However, these benefits are often not calculated because they are not set by the market. Nevertheless, the valuation of these benefits is necessary to justify a suitable investme…

Assessing the efficiency of wastewater treatment plants in an uncertain context: a DEA with tolerances approach

Abstract As the number of wastewater treatment plants (WWTPs) has increased, the economics associated with their management have become more relevant. The efficiency assessment is therefore a useful tool for cost reduction. For this purpose, Data Envelopment Analysis (DEA) is a highly suitable technique, since it is a holistic approach that aggregates performance indicators into a single index. However, one of the most common criticisms of DEA models is that information on uncertainty estimates is not provided. To overcome this limitation, we assess efficiency by using a DEA model with statistical tolerances for both inputs and outputs. This model is applied to a sample of Spanish WWTPs. Th…

Environmental Benefit of Improving Wastewater Quality: A Shadow Prices Approach for Sensitive Areas

The use of effluents from wastewater treatment plants (WWTPs) as a non-conventional source of water for wetlands in arid and semi-arid regions is becoming the most-often sought solution for maintaining water flow in sensitive wetlands there. However, the managing effluent quality should be a requirement because excess nutrients (mainly nitrogen and phosphorus) can generate eutrophication problems in wetlands. In the Mediterranean area in general, wetlands are strongly vulnerable to eutrophication, which is why they are classified as sensitive areas. Our study uses a data set from 24 WWTPs, effluents of which are discharged to wetlands in the coast of Community of Valencia. We use the shado…

Comparing the dynamic performance of wastewater treatment systems: A metafrontier Malmquist productivity index approach

The assessment of productivity change of wastewater treatment plants (WWTPs) is essential to improve the performance over time of the facilities evaluated. This study assessed and compared the productivity growth of WWTPs operating with non-homogeneous technologies. The metafrontier Malmquist productivity index (MMPI) was computed for a sample of 99 WWTPs encompassing 4 alternative technologies: activated sludge (AS), aerated lagoon (AL), trickling filter (TF) and rotating biological contactor (BD). The results indicated that, on average, WWTPs with AS and BD exhibited better performance over time than WWTPs with AL and TF. The MMPI indicates that, over the period 2007-2009, the productivit…

Economic and environmental performance of wastewater treatment plants: Potential reductions in greenhouse gases emissions

Abstract Sanitation and wastewater treatment are essential for protecting human health and environmental sustainability. Treatment processes are not free of environmental impacts; consequently assessment of the environmental performance of wastewater treatment plants (WWTPs) has gained interest in recent years. Unlike other methods, a direct approach is followed to estimate environmental performance indicators (EPIs) using data envelopment analysis (DEA), i.e. an index of overall performance is directly obtained. The present study represents pioneering work to integrate environmental impacts in the assessment of the efficiency of WWTP estimating pure (PEPI) and mixed (MEPI) environmental pe…

Economic feasibility study for intensive and extensive wastewater treatment considering greenhouse gases emissions

Economic feasibility assessments represent a key issue for selecting which wastewater treatment processes should be implemented. The few applications that exist focus on the positive economic value of externalities, overlooking the existence of negative externalities. However, wastewater treatment plants (WWTPs) consume a significant amount of energy, contributing to climate change. In this context, as a pioneering approach, greenhouse gas emissions (GHG) have been incorporated as a negative externality of wastewater treatment. Within this framework, this study aims to compare the economic feasibility of five technologies, both intensive and extensive, for small communities. The results sho…

The social benefits of restoring water quality in the context of the Water Framework Directive: A comparison of willingness to pay and willingness to accept.

The Water Framework Directive (WFD) is by far the most important piece of water legislation in Europe for the coming decades. Its main aim is to achieve "good ecological status" for all water resources by 2015. The economic valuation of the non-market benefits derived from improving water quality is an important input in assisting the design and implementation of efficient and effective water management policies. In this study, the contingent valuation method has been applied with a double purpose. On the one hand, we have estimated the value of a hypothetical improvement in water quality of a river asking individuals about their willingness to pay, and on the other hand, the issue of exemp…

Cost modelling for wastewater treatment processes

Abstract The aim of this paper is to provide a methodology for a better understanding of the cost structure of wastewater treatment processes. This methodology may be useful in the planning of new facilities. The existing models in the literature are focused on the influence of the capacity of plant, expressed as inhabitants or flow rate, on the cost of treatment. We propose a new approach for the operating cost function that includes the most representative variables in the process. The idea is that the modelling of treatment costs enables us to understand the key role of the economies of scale in this context; and also the influence of other variables such as contaminants removed, or the …

Directional distance functions and environmental regulation

Abstract In this paper we use directional technology distance functions to evaluate the impact of environmental regulations on firms’ performance. Following Fare et al. [Fare, R., Grosskopf, S., Lovell, C.A.K., Pasurka, C., 1989. Multilateral productivity comparisons when some outputs are undesirable: a nonparametric approach. The Review of Economics and Statistics 71, 90–98.], we construct an index that measures opportunity costs for individual firms arising from regulations that prevent free disposal of wastes. The methodology is applied to a sample of Spanish producers of ceramic pavements. We assume that firms maximise desirable output simultaneously reducing inputs, with no change in t…

Improving drinking water treatment without tariff impact: the Spanish case study

Abstract Water is essential for our lives and activities. Everyone can drink good quality water, the question is whether they have access to it in the first place. Water quality and its treatment depend on the water source. This treatment has costs that users have to pay in the water tariff. It is very important to establish a water tariff that permits the best water treatment and has a low impact on the users. Cost functions are a useful tool to predict costs before an implementation or improvement. This article, using three easy steps (analysis, obtaining costs and modification of the water tariff) proposes improving water purification treatment using cost functions in order to find the b…

Shadow prices of emerging pollutants in wastewater treatment plants: Quantification of environmental externalities.

Conventional wastewater treatment plants (WWTPs) are designed to remove mainly the organic matter, nitrogen and phosphorus compounds and suspended solids from wastewater but are not capable of removing chemicals of human origin, such as pharmaceutical and personal care products (PPCPs). The presence of PPCPs in wastewater has environmental effects on the water bodies receiving the WWTP effluents and renders the effluent as unsuitable as a nonconventional water source. Considering PPCPs as non-desirable outputs, the shadow prices methodology has been implemented using the output distance function to measure the environmental benefits of removing five PPCPs (acetaminophen, ibuprofen, naproxen…

Industrial Symbiosis: A Mechanism to Guarantee the Implementation of Circular Economy Practices

There is a growing concern regarding the scarcity of natural resources. The levels of resource exploitation generated by the current system of production and consumption has led the European Commission to develop a set of guidelines that aim to reduce the pressure on natural resources. The set of guidelines proposed by the European Union is based on the transformation of the current linear economic system into a circular system in which resources and materials remain in the production system for longer. However, for this change to take effect, practical measures are required. This paper presents an industrial symbiosis approach as a practical application of a circular economy model. The aim…

The Influence of Seasonality on the Economic Efficiency of Wastewater Treatment Plants

Many tourist areas are often characterized with seasonal water demand. The influence of seasonality on water management is more intensive in the context of water scarcity. Thus the use of so-called non-conventional water resources in these areas becomes a key aspect. In this sense, efficient performance, both in technical and cost terms, favors water reuse possibilities and, therefore, increases the supply of non-conventional resources. In tourist areas, seasonality is a determining factor in the efficiency of wastewater treatment plants (WWTPs) as these are operating at full capacity only during the summer season while the rest of the year they have under-utilization problems. Using the Fr…

The relevance of the design characteristics to the optimal operation of wastewater treatment plants: Energy cost assessment

Operational parameters of the wastewater treatment process do not always fit the design ones for several reasons, such as the seasonality or an inaccurate estimation of the population connected. This fact has an effect on the performance of the Wastewater Treatment Plants (WWTPs) and their energy costs. The aim of this paper is to develop a cost function for the energy cost that takes into account the mismatching between the design and the operational inflow. For this purpose, a performance index is constructed in order to represent how far the operational inflow is from the design one, and will be included in the cost model. Moreover, three cost functions, depending on the size of the plan…

Machine learning for energy cost modelling in wastewater treatment plants.

Understanding the energy cost structure of wastewater treatment plants is a relevant topic for plant managers due to the high energy costs and significant saving potentials. Currently, energy cost models are generally generated using logarithmic, exponential or linear functions that could produce not accurate results when the relationship between variables is highly complex and non-linear. In order to overcome this issue, this paper proposes a new methodology based on machine-learning algorithms that perform better with complex datasets. In this paper, machine learning was used to generate high-performing energy cost models for wastewater treatment plants, using a database of 317 wastewater…

A management and optimisation model for water supply planning in water deficit areas

Summary The integrated water resources management approach has proven to be a suitable option for efficient, equitable and sustainable water management. In water-poor regions experiencing acute and/or chronic shortages, optimisation techniques are a useful tool for supporting the decision process of water allocation. In order to maximise the value of water use, an optimisation model was developed which involves multiple supply sources (conventional and non-conventional) and multiple users. Penalties, representing monetary losses in the event of an unfulfilled water demand, have been incorporated into the objective function. This model represents a novel approach which considers water distri…

How does seasonality affect water reuse possibilities? An efficiency and cost analysis

Abstract Because of the harsh conditions of water stress and seasonal water demand in many zones, water reuse has emerged as a key alternative for achieving sustainable water management. An efficient performance by wastewater treatment plants (WWTPs) in technical and economic terms favors water reuse. However, seasonality in the flow of wastewater and in the pollutant load may be a determining factor in the efficiency of WWTPs. To evaluate if seasonality affects WWTP efficiency, analytical benchmarking methodology Data Envelopment Analysis (DEA) is used to obtain an average efficiency score for seasonal and non-seasonal plants. Given the importance of extended aeration (EA) and activated sl…

Economic and Technical Efficiency of Drinking Water Systems: An Empirical Approach for Spain

The objective of this paper is to analyze the efficiency of drinking water systems. Efficient performance, both in technical and economic terms guarantee minimum water losses in the network and reduced tariffs for the users. An analytical benchmarking methodology based on non-radial measures considering water losses as undesirable output gives us an efficiency indicator for each input used in the water supply process. These indicators, obtained by means of mathematical programming techniques, are used to rank suppliers' activity. The relation between the efficiency in the activity of the companies and the establishment of different tariffs is also analyzed. An empirical application is carry…

Energy efficiency in Spanish wastewater treatment plants: a non-radial DEA approach.

Wastewater treatment plants (WWTPs) are energy-intensive facilities. Thus, reducing their carbon footprint is particularly important, both economically and environmentally. Knowing the real operating energy efficiency of WWTPs is the starting point for any energy-saving initiative. In this article, we applied a non-radial Data Envelopment Analysis (DEA) methodology to calculate energy efficiency indices for sampling of WWTPs located in Spain. In a second stage analysis, we examined the operating variables contributing to differences in energy efficiency among plants. It is verified that energy efficiencies of the analyzed WWTPs were quite low, with only 10% of them being efficient. We found…

Economic feasibility study for wastewater treatment: a cost-benefit analysis.

Water resource management should be made from a multidisciplinary perspective. In this sense, economic research into the design and implementation of policies for the efficient management of water resources has been emphasized by the European Water Framework Directive (WFD). Cost-benefit analysis (CBA) is one of the more widely accepted economic instruments since it is a rational and systematic decision-making support tool. Moreover, the wastewater treatment process has significant associated environmental benefits. However, these benefits are often left uncalculated because they have no market value. In this paper, using the concept of shadow price, a quantification of the environmental be…

Technical efficiency and cost analysis in wastewater treatment processes: A DEA approach

In light of the growing importance of water reuse as an alternative source of water resources in many regional areas, the objective of this paper is to analyse the efficiency of wastewater treatment plants as a basic requisite to improve the potential of the water reuse. The analytical benchmarking methodology Data Envelopment Analysis (DEA) is used to calculate efficiency measurements. An efficiency index is obtained for each plant by means of mathematical programming techniques, aiming to minimise the inputs used in the water treatment process. This indicator is used as a reference to analyse plants' activity through a series of variables including the size of the plant or its cost struct…

Economic valuation of environmental benefits of removing pharmaceutical and personal care products from WWTP effluents by ozonation.

Continuous release of pharmaceutical and personal care products (PPCPs) present in effluents from wastewater treatment plants (WWTPs) is nowadays leading to the adoption of specific measures within the framework of the Directive 2000/60/EC (Water Framework Directive). The ozonation process, normally employed for drinking water production, has also proven its potential to eliminate PPCPs from secondary effluents in spite of their low concentrations. However, there is a significant drawback related with the costs associated with its implementation. This lack of studies is especially pronounced regarding the economic valuation of the environmental benefits associated to avoid the discharge of …

Life Cycle Costing: a tool to manage the urban water cycle

The Water Framework Directive puts much emphasis on the role of economics for improving the management of water resources. In the context of the urban water cycle, previous studies have proven that Life Cycle Costing (LCC) is a useful methodology for assessing the costs of the whole cycle. However, there are many elements and factors that can influence the results of the LCC assessment and therefore affect the decision making process. The main aim of this study is to identify the main difficulties for carrying out LCC studies in the urban water cycle and to propose some solutions to overcome them. Hence, the conclusions obtained from the assessment of several case studies will be more robus…

Feasibility Studies for Water Reuse Projects: Economic Valuation of Environmental Benefits

Water reuse is emerging as a promising alternative because it enables water resources to be increased and lowers pollution levels by reducing wastewater. In recent decades, significant technological progress has been made in the field of wastewater regeneration; and project feasibility is now mostly subject to just economic assessment. However, the economic aspect is the least addressed aspect of research into water reuse. This is because private costs are generally considered while the external effects are relegated to a series of statements about the advantages of water reuse. Methodologies used to analyze the economic feasibility of these projects usually focus on internal costs. As a re…

Selecting sewage sludge treatment alternatives in modern wastewater treatment plants using environmental decision support systems

The importance of the sewage sludge treatment within the field of wastewater treatment plants (WWTPs) suggests new dimensions of analysis where the relevance of economic criteria combined with the associated environmental issues are increasing the sludge management complexity. For supporting the decision process and for comparative purposes, this study assesses five alternative configurations for sludge treatment, namely: mesophilic and termophilic anaerobic digestion plus composting, incineration, gasification, and supercritical water oxidation (SCWO). The global warming potential (GWP) and the annual cash flow of each alternative are used to estimate a composite indicator for each alterna…

Analysing the efficiency of wastewater treatment plants: The problem of the definition of desirable outputs and its solution

Abstract Evaluating the efficiency of wastewater treatment plants (WWTPs) is highly relevant to improve their performance from an economic and environmental perspective. The issue is even more critical in countries where WWTPs are benchmarked to regulate water companies and define WWTPs’ economic and environmental objectives. Despite the large number of previous studies on this topic, none has considered that the amount of outputs produced by the WWTPs is restricted by the concentration of pollutants in the effluent. To overcome this limitation, the study’s main objective was to propose a new variant of the Weighted Russell Directional Distance Model (WRDDM) that would solve problems regard…

Environmental and economic profile of six typologies of wastewater treatment plants

The objective of wastewater treatment plants (WWTPs) is to prevent pollution. However, it is necessary to assess their sustainability in order to ensure that pollution is being removed, not displaced. In this research, the performance of 24 WWTPs has been evaluated using a streamlined Life Cycle Assessment (LCA) with Eutrophication Potential (EP) and Global Warming Potential (GWP) as environmental indicators, and operational costs as economic indicators. WWTPs were further classified in six typologies by their quality requirements according to their final discharge point or water reuse. Moreover, two different functional units (FU), one based on volume (m(3)) and the other on eutrophication…

A data-driven methodology to support pump performance analysis and energy efficiency optimization in Waste Water Treatment Plants

Abstract Studies and publications from the past ten years demonstrate that generally the energy efficiency of Waste Water Treatment Plants (WWTPs) is unsatisfactory. In this domain, efficient pump energy management can generate economic and environmental benefits. Although the availability of on-line sensors can provide high-frequency information about pump systems, at best, energy assessment is carried out a few times a year using aggregated data. Consequently, pump inefficiencies are normally detected late and the comprehension of pump system dynamics is often not satisfactory. In this paper, a data-driven methodology to support the daily energy decision-making is presented. This innovati…

Energy saving in WWTP: Daily benchmarking under uncertainty and data availability limitations

Efficient management of Waste Water Treatment Plants (WWTPs) can produce significant environmental and economic benefits. Energy benchmarking can be used to compare WWTPs, identify targets and use these to improve their performance. Different authors have performed benchmark analysis on monthly or yearly basis but their approaches suffer from a time lag between an event, its detection, interpretation and potential actions. The availability of on-line measurement data on many WWTPs should theoretically enable the decrease of the management response time by daily benchmarking. Unfortunately this approach is often impossible because of limited data availability. This paper proposes a methodolo…

Editorial: Special Issue on Economics of Wastewater Treatment and Reuse

Comparing the efficiency of wastewater treatment technologies through a DEA metafrontier model

Abstract The assessment of economic and technical efficiency is a useful tool to select the most appropriate technology for wastewater treatment. However, traditional models require that the units being assessed operate with the same technology. To overcome this limitation, we investigate the viability of using a non-concave metafrontier approach that is based on data envelopment analysis (DEA) to calculate the techno-economic efficiency and technological gap ratios (TGRs) of wastewater treatment plants (WWTPs) operating with non-homogeneous technologies. The model is applied to a sample of 99 Spanish WWTPs, encompassing four alternative technologies: activated sludge; aerated lagoon; trick…

Assessment of domestic water consumption in Valencia city through fuzzy-set qualitative comparative analysis

The influence of quantitative and qualitative population conditions needs to be jointly considered in the assessment of urban water demand. Through fuzzy-set qualitative comparative analysis (fsQCA...

Cost–benefit analysis of water-reuse projects for environmental purposes: A case study for Spanish wastewater treatment plants

Water reuse is an emerging and promising non-conventional water resource. Feasibility studies are essential tools in the decision making process for the implementation of water-reuse projects. However, the methods used to assess economic feasibility tend to focus on internal costs, while external impacts are relegated to unsubstantiated statements about the advantages of water reuse. Using the concept of shadow prices for undesirable outputs of water reclamation, the current study developed a theoretical methodology to assess internal and external economic impacts. The proposed methodological approach is applied to 13 wastewater treatment plants in the Valencia region of Spain that reuse ef…

Productive Efficiency and Territorial Externalities in Small and Medium-Sized Industrial Firms: A Dynamic Analysis of the District Effect

A series of works have analysed differential behaviour in terms of productive efficiency between companies inside a hypothetical industrial district and those outside the district. This objective has been addressed using measures of technical efficiency. The results obtained provide valuable information for quantifying the district effect at a given moment in time. However, constant changes in the market and business behaviour mean that it is worthwhile studying the business district effect from a dynamic point of view. In this study, we provide this new vision through the use of Malmquist productivity indices. This methodology enables us to analyse possible differential evolutions by compa…

The calculation of shadow prices for industrial wastes using distance functions: An analysis for Spanish ceramic pavements firms

Abstract This paper deals with the calculation of shadow prices for two industrial wastes generated on their production processes by 18 firms belonging to the Spanish ceramic pavements industry. These prices are then used to calculate an extended productivity index which takes into consideration wastes going with the production of marketable goods. We follow the methodological approach first proposed by Fare et al. (The Review of Economics and Statistics 75 (1993)). A negative correlation is found between absolute shadow prices and wastes production intensity, reflecting a greater marginal cost of eliminating wastes for those firms using less contaminant production processes. Differences be…

Modelling the energy costs of the wastewater treatment process: The influence of the aging factor.

Wastewater treatment plants (WWTPs) are aging and its effects on the process are more evident as time goes by. Due to the deterioration of the facilities, the efficiency of the treatment process decreases gradually. Within this framework, this paper proves the increase in the energy consumption of the WWTPs with time, and finds differences among facilities size. Accordingly, the paper aims to develop a dynamic energy cost function capable of predicting the energy cost of the process in the future. The time variable is used to introduce the aging effects on the energy cost estimation in order to increase the accuracy of the estimation. For this purpose, the evolution of energy costs will be …

Cost analysis of the facilities deterioration in wastewater treatment plants: A dynamic approach

Abstract The implementation of the Directive 91/271 / CEE resulted in the proliferation of new Wastewater Treatment Plants (WWTPs) all around Europe. These facilities, which are compound by a wide range of assets (civil works, electromechanical equipment, pipelines, etc.), are ageing and deteriorating having an impact on the efficiency of the process. It is founded that repairs and corrective maintenance costs have increased in the last years, due to the deterioration process. Therefore, the aim of the present study is to focus on the cost effects of the deterioration process of the facilities in different wastewater treatment technologies. The analysis of these impacts will allow the opera…

Environmental performance: an index number approach

Abstract Tyteca [J. Environ. Manage. 46 (1996) 281] reviews the literature on environmental performance indicators. In that paper he calls for an index that simultaneously accounts for resources used, good outputs produced and pollutants or undesirable outputs emitted. Here, we provide a formal index number of environmental performance which can be computed using data envelopment analysis (DEA) techniques. The implicit benchmark is that of finding the highest ratio of good to bad outputs. Our environmental performance index is constructed from distance functions which implies that it satisfies a number of desirable properties. Since the component distance functions require only information …

The influence of oversizing on maintenance cost in wastewater treatment plants

Abstract Management of Wastewater Treatment Plants (WWTPs) is a complex process, not only from a technical point of view but also from an economic point of view. There are several factors that influence the wastewater treatment process and can cause an increase in management costs. One of these factors is the treatment capacity, in particular the WWTPs’ oversizing problem. The difference between the design population equivalent (p.e.) and the actual p.e. treated generates imbalances in the wastewater treatment process costs. This paper analyses the influence that oversizing has on the maintenance costs for WWTPs in the Valencia region (Spain). Through an econometric approach, the behaviour …

Pump Efficiency Analysis of Waste Water Treatment Plants: A Data Mining Approach Using Signal Decomposition for Decision Making

In Waste Water Treatment Plants (WWTPs), the pump systems are one of the most energy intensive processes. An efficient energy management of pumps should produce environmental and economic benefits. In this paper, we propose a daily data-driven approach for a detailed pump efficiency analysis that reduces the time gap between an inefficiency and its detection, provides detailed information for decision making by using new Key Performance Indicators (KPIs), and detects inefficient pump set-ups and designs. The proposed approach based on signal decomposition relies on sensors generally available in WWTPs, e.g. daily pump inflow and energy consumption. Moreover, it allows decomposing the data s…

Voluntary Agreements to Promote the Use of Reclaimed Water at Tordera River Basin

The voluntary agreement to promote the use of reclaimed water is an economic policy instrument (EPI) which focuses on improving water management by using reclaimed water. Following a win-win strategy, this EPI was implemented in the Tordera river basin (Spain), an area with endemic water scarcity problems and high competition among users for water resources. The assessment of the EPI suggests that significant positive outcomes have achieved from an environmental and economic point of view. Thus, the demand of freshwater has decreased and the availability of water is guaranteed even during summer period allowing therefore for the maintenance of economic activities (agriculture and golf cours…

ECONOMIC AND TECHNICAL EFFICIENCY OF WASTEWATER PLANTS: A BASIC REQUISITE TO THE FEASIBILITY OF WATER REUSE PROJECTS

The water reuse could be considered essential both from a social and also an environmental and health point of view. In light of the growing importance of water reuse as an alternative source of water resources in many regional areas, the objective of this paper is to analyse the efficiency of wastewater treatment plants. Efficient performance, both in technical and economic terms favours reuse possibilities and, therefore, increases the water supply. An analytical benchmarking methodology based on non-radial measures gives us an efficiency indicator for each input considered in the wastewater treatment process. These indicators, obtained by means of mathematical programming techniques, are…

A Tool for Energy Management and Cost Assessment of Pumps in Waste Water Treatment Plants

Waste Water Treatment Plants (WWTPs) are generally considered energy intensive. Substantial energy saving potentials have been identified by several authors. Pumps consume around 12% of the overall WWTP energy consumption. In this paper we propose a methodology that uses the sensors commonly installed in WWTPs, such as volume and energy sensors, to perform energy benchmarking on pumps. The relationship between energy efficiency and flow rate is used to detect specific problems, and potential solutions are proposed, taking into consideration economical and environmental criteria (cost of externalities in energy production). The methodology integrates energy benchmarking, data-mining, and eco…

Efficiency of wastewater treatment facilities: The influence of scale economies.

The water cycle, from catchment to discharge, is a sector that involves an important investment and operation and maintenance costs. In particular, sewage treatment is a challenge for governments because they are having to consider economic, environmental, and social aspects. Within the European Union, implementation of Directive 91/271/EEC is responsible for the location of wastewater treatment facilities in the territory, due to the requirement that all urban areas must have this infrastructure to reduce the environmental impact of treated water in water bodies. Different sizes of municipalities affect the design of each wastewater treatment plant (WWTP) and cause variations in the operat…

Economic effects of the consolidation of water utilities in Japan

Water utilities are affected by economies of scale. However, in Japan most water utilities are small-scale water services. Therefore, they face enormous difficulties in terms of financial and personnel resources. To take advantage of economies of scale, the consolidation of water utilities has been promoted since 1965 by Japanese water authorities. The measure has been successful to some extent; nevertheless, consolidation has not progressed in recent years as was expected. This paper identifies the main barriers that hinder the consolidation of water utilities in Japan and describes the new promotion plan for the consolidation of water utilities developed by the Japan Water Works Associati…

Current state of water management in Japan

Financial sustainability of water utilities is essential to guarantee the provision of high quality services. The aims of this paper are to review the current state of water management in Japan and to identify the main difficulties which confront Japanese water utilities. As the facilities built when the country expanded water utilities rapidly are drawing near the renewal period concurrently, water operators must quickly accelerate facility renewal work. The statistical data from the Japan Water Works Association illustrate that one of the most significant challenges facing Japanese water utilities is to finance investments to renew facilities and to prepare them for earthquakes. Difficult…

Energy saving in wastewater treatment plants: A plant-generic cooperative decision support system

Abstract In Europe, the analysis of Waste Water Treatment Plants (WWTPs) shows a significant energy efficiency potential (up to 25%). Optimistically, plant managers assess their plant efficiency once or twice per year. Consequently, the time gap between an inefficiency and its detection produces avoidable operational costs. Although the installation of multiple on-line sensors can provide detailed energy information, for a human operator it is unrealistic to analyse the produced data in a satisfactory time-scale. This paper proposes a cooperative tool for energy saving that remotely accesses and evaluates WWTP databases to produce daily energy assessment reports. The novelty of this decisio…

Assessing disproportionate costs to achieve good ecological status of water bodies in a Mediterranean river basin.

Water management is becoming increasingly important as the demand for water grows, diversifies, and includes more complex environmental concerns. The Water Framework Directive (WFD) seeks to achieve a good ecological status for all European Community water bodies by 2015. To achieve this objective, economic consideration of water management must be given to all decision-making processes. Exemption (time or level of stringency) from the objectives of the EU Directive can be justified by proving that the cost of implementing measures is disproportionate to the benefits. This paper addresses the issue of disproportionate costs through a cost-benefit analysis (CBA). To predict the costs, the fu…

Assessment of wastewater treatment alternatives for small communities: An analytic network process approach

The selection of the most appropriate wastewater treatment (WWT) technology is a complex problem since many alternatives are available and many criteria are involved in the decision-making process. To deal with this challenge, the analytic network process (ANP) is applied for the first time to rank a set of seven WWT technology set-ups for secondary treatment in small communities. A major advantage of ANP is that it incorporates interdependent relationships between elements. Results illustrated that extensive technologies, constructed wetlands and pond systems are the most preferred alternatives by WWT experts. The sensitivity analysis performed verified that the ranking of WWT alternatives…

Cost modeling for sludge and waste management from wastewater treatment plants: an empirical approach for Spain

Abstract Wastewater treatment involves the generation of large volumes of sludge and other waste. Managing this waste in an economical and environmentally acceptable way has become a matter of increasing importance over the last few years. While the technologies and processes to reduce sludge generation are being widely studied, research on the economic aspects is much more limited. This study applies a cost-modeling methodology that uses statistical information from a sample of Spanish wastewater treatment plants (WWTPs) to generate a sewage sludge and waste management cost function with the aim of contributing to a better understanding of the cost structure and predicting the cost savings…

Economic valuation of environmental benefits from wastewater treatment processes: An empirical approach for Spain

Economic research into the design and implementation of policies for the efficient management of water resources has been emphasized by the European Water Framework Directive (Directive 2000/60/EC). The efficient implementation of policies to prevent the degradation and depletion of water resources requires determining their value in social and economic terms and incorporating this information into the decision-making process. A process of wastewater treatment has many associated environmental benefits. However, these benefits are often not calculated because they are not set by the market, due to inadequate property rights, the presence of externalities, and the lack of perfect information…

A review of Payment for Ecosystem Services for the economic internalization of environmental externalities: A water perspective

Abstract The allocation of economic value to environmental goods is intended to internalize the socio-economic and environmental costs of policies implemented and thus recognizes the value of the ecosystem and the consequences of environmental damage. This entails identifying the costs and benefits of management measures for conservation and of degraded ecosystems. The difficulties of this task are: (i) they are goods that have no market and (ii) there is a need for economic funding for conservation purposes. Payment for Ecosystem Services (PES) seeks to internalize the environmental externalities of human actions, ascribing monetary value to Ecosystem Services (ES) and helping decision-mak…

Cost Modelling In Waste Water Treatment Processes: An Empirical Analysis For Spain

The reuse of resources obtained from regenerating wastewater is an absolute must both from a social and also environmental and health viewpoint. For any water reuse project to be viable, water treatment processes must be optimised. In this sense, extensive knowledge of the structure of costs associated to each of the treatment technologies available is necessary. This research applies cost modelling methodology by adjusting a series of representative functions and an empirical analysis is undertaken for a sample of wastewater treatment plants in Spain.