0000000000786297
AUTHOR
María Molinos-senante
showing 75 related works from this author
Development and application of the Hicks-Moorsteen productivity index for the total factor productivity assessment of wastewater treatment plants
2015
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
2012
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
2012
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…
Eco-efficiency assessment of wastewater treatment plants using a weighted Russell directional distance model
2016
Abstract Improving the performance of wastewater treatment plants is essential to ensuring their long-term sustainability. Most of the previous studies on this topic have assessed the techno-economic efficiency of wastewater treatment plants and ignored the emission of greenhouse gases. For the first time, the weighted Russell directional distance model was applied to estimate the eco-efficiency of a sample of real wastewater treatment plants. Moreover, this approach allowed an inefficiency score to be obtained for each variable (cost factors, pollutant removal and greenhouse gases) involved in the model. Subsequently, a second stage of analysis was applied to identify factors influencing t…
Comparing changes in productivity among private water companies integrating quality of service: A metafrontier approach
2019
Abstract Most previous studies evaluating the effect of ownership on the performance of water companies have ignored the fact that there are several types of private water companies. In this study, we instead recognize that private water companies can differ considerably in how they are managed, based on whether their infrastructure is privately or publicly owned. We estimated change in productivity of fully-privatized companies and concessionary companies by employing the metafrontier Malmquist Luenberger productivity (MMLP) index, which allowed us to integrate quality-of-service variables as undesirable outputs. We segregated the MMLP index to assess changes over time in relative efficien…
Marginal abatement cost of carbon dioxide emissions in the provision of urban drinking water
2021
Abstract Reducing greenhouse gas emissions is a major challenge faced by cities seeking to improve their environmental sustainability. Doing so requires a good understanding of the costs associated with lowering emissions and factors that may influence this cost. This study estimated the marginal abatement cost of reducing both direct and indirect CO2 emissions in the provision of drinking water by several water companies in England and Wales. The results indicated that during the years 2013–2018, the average cost to the English and Welsh water industry to prevent 1 kg of CO2 emissions was 0.264₤ which was equivalent to 61% of the price of the delivered drinking water The results of the Mor…
Productivity growth of wastewater treatment plants – accounting for environmental impacts: a Malmquist-Luenberger index approach
2015
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…
Current status and development of sanitation and wastewater treatment in the national and international context
2012
El acceso al saneamiento y depuración de aguas residuales es un aspecto de suma importancia tanto desde el punto de vista ambiental como sanitario. Por ello, desde el Imperio Mesopotámico hasta la actualidad se han producido importantes avances en esta materia. Sin embargo, en la actualidad, en la mayoría de los países en vías de desarrollo el acceso al saneamiento continua siendo deficitario. Por otra parte, los países desarrollados, que sí disponen de sistemas adecuados de depuración de aguas residuales, se enfrentan al reto de mejorar la sostenibilidad de estos sistemas. En este trabajo se describe en profundidad el estado actual y evolución en el tiempo del saneamiento y depuración de a…
Cost-effectiveness analysis of sewer mining versus centralized wastewater treatment: Case study of the Arga river basin, Spain
2015
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
2015
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
2012
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…
Assessing the efficiency of wastewater treatment plants in an uncertain context: a DEA with tolerances approach
2012
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…
Estimating the cost of improving service quality in water supply: A shadow price approach for England and wales
2015
Service quality to customers is an aspect that cannot be ignored in the performance assessment of water companies. Nowadays water regulators introduce awards or penalties to incentivize companies to improve service quality to customers when setting prices. In this study, the directional distance function is employed to estimate the shadow prices of variables indicating the lack of service quality to customers in the water industry i.e., written complaints, unplanned interruptions and properties below the reference level. To calculate the shadow price of each undesirable output for each water company, it is needed to ascribe a reference price for the desirable output which is the volume of w…
Comparing the dynamic performance of wastewater treatment systems: A metafrontier Malmquist productivity index approach
2015
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…
Water company productivity change: A disaggregated approach accounting for changes in inputs and outputs
2021
Abstract The assessment of the productivity change of water utilities provides essential information to sector managers and regulators. This study uses the Luenberger-Hicks-Moorsteen Productivity Indicator (LHMPI) to evaluate productivity change as it can be further decomposed into three components namely technical change (TC), technical efficiency change (TEC), and scale efficiency change (SEC). This study evaluates the productivity of several water companies in England and Wales from 2001 to 2018. We found that productivity declined 1.2% per year due to the use of inputs that increased by 1.4% per year relative to outputs that increased by 0.2% per year.
Economic and environmental performance of wastewater treatment plants: Potential reductions in greenhouse gases emissions
2014
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
2013
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…
Cost modelling for wastewater treatment processes
2011
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 …
The Luenberger productivity indicator in the water industry: An empirical analysis for England and Wales
2014
Abstract We innovate in the field of water companies' performance with an application of the directional distance function and the Luenberger productivity indicator (LPI) to the assessment of water companies' productivity growth. The advantage of our approach is that it takes into account both input contractions and output expansions. The analysis covered 22 water companies from England and Wales using data over the period 2001–2008. To the best of our knowledge, there are no prior studies applying the Luenberger productivity indicator to the water industry in England and Wales or other countries. For the sake of comparison, the traditional Malmquist productivity index (MPI) was also estima…
Financial winners and losers since the privatization of the English and Welsh water and sewerage industry: a profit decomposition approach
2020
Evaluating changes in profit, price and productivity over time can be of great importance for regulated water industries. We investigate the drivers of profit, price (capital, labour and other inputs) and productivity change (cost efficiency change, technical change and scale effect) and the recipients of productivity change (consumers, the business itself, employees and other resource suppliers) of the English and Welsh water and sewerage companies over the period of 1995–2016. The results indicate that the profit decreased over time due to the negative quantity effect, which offset the positive price effect. A further decomposition of the quantity effect illustrates the negative impact of…
The Influence of Seasonality on the Economic Efficiency of Wastewater Treatment Plants
2010
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…
Measuring the eco-efficiency of wastewater treatment plants under data uncertainty
2018
Abstract Eco-efficiency assessment is a useful tool for improving the sustainability of wastewater treatment plants (WWTPs). However, it is a complex task that requires the integration of several performance indicators into a single index. Data envelopment analysis (DEA) is established as a highly effective methodology for achieving this as it permits the integration of the service value, resource consumption and environmental impact variables as the desirable outputs, inputs and undesirable outputs, respectively. However, traditional DEA models omit uncertainties in the data that are likely to result in biased conclusions. This study pioneers the assessment of the eco-efficiency of WWTPs w…
A management and optimisation model for water supply planning in water deficit areas
2014
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
2012
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…
Changes in the total costs of the English and Welsh water and sewerage industry: The decomposed effect of price and quantity inputs on efficiency
2020
Abstract Understanding what drives changes in regulated water companies' costs is of great relevance to water regulators. This study decomposes and estimates the change in total costs for a sample of ten water and sewerage companies in England and Wales from 1993 to 2016. The results demonstrate that companies' total costs increased over time due to increases in input prices and input quantity. Any gains obtained from the efficient allocation of resources and technical progress were lost due to mergers and technical inefficiency. Finally, we link our results with the regulatory cycle to evaluate the impact of the regulatory regime on companies' costs and discuss some policy implications.
Energy efficiency in Spanish wastewater treatment plants: a non-radial DEA approach.
2011
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…
Productivity change of the Spanish Port System: impact of the economic crisis
2016
The main goal of this study was to assess the impact of the economic crisis on the productivity growth of the Spanish Port System (SPS). The Malmquist Productivity Index (MPI) was estimated for the 28 Port Authorities of the SPS, for a 'non-crisis period' (2005-2008) and a 'crisis period' (2008-2011). From a policy perspective, the MPI is a very useful approach for assessing the productivity change because it can be decomposed into the catching-up index and the frontier productivity index. The results showed that the economic crisis did not impact all of the Spanish Port Authorities equally. Some Port Authorities presented higher productivity growth during the crisis period than in the non-…
Economic feasibility study for wastewater treatment: a cost-benefit analysis.
2010
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…
Evaluation of energy performance of drinking water treatment plants: Use of energy intensity and energy efficiency metrics
2018
Abstract One of the United Nations Sustainable Development Goals is to provide access to safe and clean drinking water. However, treating raw water in facilities currently involves using a non-negligible amount of energy, and the fossil fuels used are both expensive and emit greenhouse gases when combusted. Previous studies have evaluated the energy performance of drinking water treatment plants by estimating the amount of energy consumed per volume of water. However, such studies have not accounted for differences between treatment technologies and have assumed a common standard water treatment technology. To overcome these limitations, this study employed metafrontier data envelopment ana…
Energy intensity modeling for wastewater treatment technologies.
2018
Wastewater treatment plants (WWTPs) are energy intensive facilities; therefore increased pressure has been placed on managers and policy makers to reduce the facilities' energy use. Several studies were conducted to compare the energy intensity (EI) of WWTPs, which showed large dispersion in EI among the facilities. In the present study, the degree EI influenced WWTPs was tested using a set of technical variables by modeling the EI of a 305 WWTP sample grouped into five secondary treatment technologies. Results indicated the following two major findings: i) WWTPs using conventional activated sludge, extended aeration, trickling biofilters, and biodisks exhibited significant economies of sca…
Economic valuation of environmental benefits of removing pharmaceutical and personal care products from WWTP effluents by ozonation.
2013
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 …
Eco-Efficiency of the English and Welsh Water Companies: A Cross Performance Assessment
2021
Analyzing costs and greenhouse gas (GHG) emissions could be of great importance for the water utilities to supply water services in a healthy and sustainable manner. In this study, we measured the eco-efficiency of several water utilities in England and Wales by incorporating GHG as an undesirable output. For the first time, we evaluated the eco-efficiency of the water production process using robust cross-efficiency data envelopment analysis (DEA) techniques. The further use of clustering and regression techniques allowed us to better understand the drivers of eco-efficiency. The results showed that the mean eco-efficiency of the water sector was 0.748, which indicates that costs and GHG e…
Life Cycle Costing: a tool to manage the urban water cycle
2013
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
2010
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…
Dynamic goal programming synthetic indicator: an application for water companies sustainability assessment
2018
ABSTRACTThis study proposes to evaluate the sustainability of water companies through time by using a new approach, one that involves a dynamic synthetic indicator derived from goal programming techniques. This dynamic indicator approach incorporates catch-up and innovation indices, which enables one to identify the main factors that drive changes in sustainability through time. We used a case study approach to clarify this dynamic approach by evaluating indicator values from a sample of 129 Portuguese water companies over the 2012 to 2015 time period. For most of the water companies we evaluated, sustainability values changed over time, which illustrates the importance of evaluating dynami…
Assessing changes in eco-productivity of wastewater treatment plants: The role of costs, pollutant removal efficiency, and greenhouse gas emissions
2018
Abstract Improving eco-efficiency of wastewater treatment plants (WWTPs) has been identified as being essential for achieving urban sustainability. Several previous papers have evaluated the eco-efficiency of WWTPs using data envelopment analysis (DEA) models. However, those models provided only a static assessment in that they ignored possible fluctuations over time within each plant. To overcome this temporal limitation, this paper evaluates dynamic eco-efficiency (changes in eco-productivity over time) of WWTPs using the dynamic weighted Russell directional distance model (WRDDM). This approach allows one to obtain an eco-productivity change index for each major component of the WRDDM mo…
Impact of external costs of unplanned supply interruptions on water company efficiency: Evidence from Chile
2020
Abstract Conventional performance assessments of water companies ignore the external costs due to water supply outages. To overcome this gap, we evaluate the impact of external costs of unplanned supply interruptions on the efficiency of water companies. Two efficiency metrics, internal technical efficiency (ITE), and total technical efficiency (TTE), were estimated based on data envelopment analysis (DEA). The results evidence that the external costs of unplanned water supply interruptions impact, on average, 7.9% of the efficiency of water companies. We also explored the impact of a set of environmental variables on water company efficiency.
Profit change and its drivers in the English and Welsh water industry: is output quality important?
2014
Abstract The assessment of profit change over time and its drivers is essential to analyse firms' financial performance. This paper investigates profit change and its components for the 10 English and Welsh water and sewerage water companies over the period 1991–2008 and for three regulatory sub-periods. Profit changes and their drivers are computed following two approaches, namely: without controlling for water and sewerage quality issues, and after decomposing the output effect into high quality and low quality output effect. In both cases, profit change is decomposed into various factors such as quantity and price effect, technical change, efficiency change, resource mix, product mix, an…
Benchmarking energy efficiency of water treatment plants: Effects of data variability
2019
This study evaluates, for the first time, the energy efficiency of a sample of drinking water treatment plants (DWTPs) using the data envelopment analysis (DEA) tolerance method, which is based on the simulation of scenarios to integrate data variations. The integration of data uncertainty in energy efficiency estimation changes drastically results for approximately one-third of the DWTPs evaluated. The results showed that, even in the best-case scenario, most of the DWTPs evaluated are inefficient and may therefore, be able to reduce the energy used to treat raw water. From a policy perspective, the findings of this study reveal that omitting data variability in benchmarking would involve …
Selecting sewage sludge treatment alternatives in modern wastewater treatment plants using environmental decision support systems
2015
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
2020
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…
Assessing the dynamic eco-efficiency of Italian municipalities by accounting for the ownership of the entrusted waste utilities
2021
Abstract This study evaluates and compares the dynamic eco-efficiency of municipalities with publicly owned, privately owned, and mixed ownership solid waste utilities by estimating the Meta-frontier Malmquist-Luenberger productivity index for a sample of 68 major Italian towns. On average, the eco-productivity of Italian waste service providers increased by 8% from 2016 to 2019. Although municipalities with private utilities improved their eco-productivity most, the differences among the three clusters reflecting utility ownership are not statistically significant. The results show that publicly owned waste operators drive technology and that the technological levels of private utilities h…
Assessing productivity changes in water companies: a comparison of the Luenberger and Luenberger-Hicks-Moorsteen productivity indicators
2018
Interest in evaluating productivity changes in water companies has increased in recent years. In this paper, for the first time, we employ the Luenberger-Hicks-Moorsteen Productivity Indicator (LHMPI) to evaluate productivity changes in a sample of Chilean water companies from 2010 to 2016. Productivity change estimations obtained by both the Luenberger Productivity Indicator (LPI) and the LHMPI are compared. Moreover, both indicators were computed assuming constant and variable returns to scale technologies. The LHMPI estimates illustrate that productivity in Chilean water companies has slightly improved over the period studied due to the positive trend of outputs, whereas the inputs negat…
Environmental and economic profile of six typologies of wastewater treatment plants
2011
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…
Estimating the environmental and resource costs of leakage in water distribution systems: A shadow price approach.
2016
Water scarcity is one of the main problems faced by many regions in the XXIst century. In this context, the need to reduce leakages from water distribution systems has gained almost universal acceptance. The concept of sustainable economic level of leakage (SELL) has been proposed to internalize the environmental and resource costs within economic level of leakage calculations. However, because these costs are not set by the market, they have not often been calculated. In this paper, the directional-distance function was used to estimate the shadow price of leakages as a proxy of their environmental and resource costs. This is a pioneering approach to the economic valuation of leakage exter…
Comparing the efficiency of wastewater treatment technologies through a DEA metafrontier model
2011
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…
Cost–benefit analysis of water-reuse projects for environmental purposes: A case study for Spanish wastewater treatment plants
2011
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…
Performance assessment of water companies: A metafrontier approach accounting for quality of service and group heterogeneities
2021
Abstract The assessment of water companies’ efficiency, productivity and quality of service is part of the process to set water tariffs and therefore, is relevant for regulators and customers. However, the water industry involves several heterogeneous water companies. Following a pioneering approach, this study estimates productivity change and its drivers considering the non-homogeneous nature of the water companies and incorporating quality of service variables as undesirable outputs. In doing so, the metafrontier Malmquist Luenberger productivity index was estimated for a sample of English and Welsh water and sewerage companies (WaSCs) and water only companies (WoCs) over the years 2001–…
Assessing the productivity change of water companies in England and Wales: A dynamic metafrontier approach
2017
The assessment of productivity change and its drivers across water companies and over time is a powerful tool for both regulators and companies when setting water tariffs. Water and sewerage companies (WaSCs) and water only companies (WoCs) provide different services. Hence, their productivity change cannot directly be evaluated jointly. In this paper and for the first time, we provide a pioneering approach to assess and compare the dynamics of productivity change of WaSCs and WoCs. To achieve this, both the traditional Malmquist productivity index and the metafrontier Malmquist productivity index and its components are computed to assess the productivity change for a sample of English and …
Voluntary Agreements to Promote the Use of Reclaimed Water at Tordera River Basin
2015
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…
Assessing the sustainability of small wastewater treatment systems: A composite indicator approach
2014
The assessment of the sustainability of wastewater treatment (WWT) systems has gained interest in recent years. However, most previous studies have focused on environmental and/or economic dimensions ignoring social aspects. Moreover, they tend to be based on sets of indicators rather than providing a holistic assessment. To overcome this limitation, this paper proposes an innovative methodology to assess the sustainability of WWT systems based on the development of a composite indicator embracing economic, environmental and social issues. Subsequently, the global sustainability of seven WWT technologies for secondary treatment in small communities is compared. The joint application of the …
Assessing the efficiency of Chilean water and sewerage companies accounting for uncertainty
2016
Abstract Efficiency assessment of water and sewerage companies (WaSCs) has attracted considerable attention both for water company managers and water regulators. Within the methodological approaches that can be applied to estimate efficiency scores, data envelopment analysis (DEA) is the most widely applied technique. In spite of the positive features of DEA, it presents a major drawback which is its deterministic nature. In other words, conventional DEA models do not account for uncertainty in the data. To overcome this limitation, we assess, for the first time, the efficiency of a sample of Chilean WaSCs by using a DEA model with statistical tolerance in the data. Hence, 81 efficiency sco…
Eco-efficiency assessment of municipal solid waste services: Influence of exogenous variables.
2020
Abstract Improving the eco-efficiency of municipalities in the provision of municipal solid waste (MSW) services is fundamental in the context of a circular economy. This study evaluates the eco-efficiency of a sample of Spanish municipalities, integrating the total cost as input, recyclable waste as desirable output, and unsorted waste as undesirable output. Following a pioneering approach, the weighted Russell directional distance model (a non-radial data envelopment analysis model) was employed, which allowed us to obtain a global inefficiency score and individual inefficiency scores for each variable integrated in the model. In the second stage of analysis, the potential factors affecti…
Assessing the sustainability of water companies: A synthetic indicator approach
2016
Performance indicators (PIs) are essential in the benchmarking process used to rate and rank water companies. However, a set of individual PIs does not provide a holistic assessment of company performance from multiple perspectives. A multidimensional evaluation of the performance of water companies can be achieved by aggregating the PIs into a synthetic indicator. Although the concept of sustainability involves economic, environmental and social criteria, most of the previous studies have not considered these three dimensions simultaneously. This paper discusses a process of indicator aggregation using two approaches based on multi-criteria decision analysis to evaluate and compare the sus…
Including the environmental criteria when selecting a wastewater treatment plant
2014
Abstract Life Cycle Assessment (LCA) is a methodology to generate environmental impact estimates associated with the life cycle stages of a product or process. The approach facilitates a more comprehensive outlook of the end-of-pipe process impacts, in which wastewater treatment plants (WWTPs) are included. Here we describe the implementation of the LCA methodology within a knowledge-based Decision support system (DSS) in order to include the environmental criteria to the decision making process when selecting the most appropriate process flow diagrams for specific scenarios. A sample group of 22 actual operating facilities in Spain, corresponding to five different typologies were assessed …
Efficiency assessment of wastewater treatment plants: A data envelopment analysis approach integrating technical, economic, and environmental issues
2015
The assessment of the efficiency of wastewater treatment plants (WWTPs) is essential to compare their performance and consequently to identify the best operational practices that can contribute to the reduction of operational costs. Previous studies have evaluated the efficiency of WWTPs using conventional data envelopment analysis (DEA) models. Most of these studies have considered the operational costs of the WWTPs as inputs, while the pollutants removed from wastewater are treated as outputs. However, they have ignored the fact that each pollutant removed by a WWTP involves a different environmental impact. To overcome this limitation, this paper evaluates for the first time the efficien…
Assessing the quality of service to customers provided by water utilities: A synthetic index approach
2017
Abstract Currently, water and sewer companies face the challenge of improving their quality of service to customers (QSC). Performance indicators are essential to monitor and benchmark the QSC of water companies; however, individual indicators do not provide a holistic evaluation of the quality of water and sewer services provided to customers. This study proposes an innovative QSC index based on distance-function techniques that makes it possible to compare changes in the QSC of water companies among locations and temporal periods. A case study assesses changes in QSC for a sample of Chilean water and sewer companies from 2007 to 2014. The results show that in spite of the efforts made by …
Accounting for service quality to customers in the efficiency of water companies: evidence from England and Wales
2015
This paper investigates the role of service quality to customers in the efficiency assessment of water companies in England and Wales. To achieve this, data envelopment analysis techniques are employed to compute the technical efficiency of the water companies following two approaches: (i) traditional assessment based on quantity variables (without the inclusion of service quality variables) and (ii) alternative assessment considering quantity and service quality variables as undesirable outputs. The analysis covers 22 water and sewerage companies and water only companies providing drinking water services. The results indicate that the traditional efficiency assessment reveals a high level …
Assessment of the Total Factor Productivity Change in the Spanish Ports: Hicks–Moorsteen Productivity Index Approach
2016
AbstractThe assessment of the productivity growth of ports is essential to improve their performance and competitiveness. Although there are several nonparametric methodologies to compute the productivity change, the Hicks–Moorsteen productivity index is the only multiplicatively completed index that can be computed without price data. For the first time, the total factor productivity (TFP) change of a sample of ports is evaluated. The analysis covers the 28 ports comprising the Spanish port system, using data over the period 2005–2012. The drivers of TFP—technical change, technical efficiency, mix efficiency, and residual scale efficiency—are also investigated. The results indicate that fr…
How much should customers be compensated for interruptions in the drinking water supply?
2017
Water supply interruptions directly affect customers, and customers should be compensated accordingly. However, few water regulators have applied compensation policies given the difficulty of estimating the economic value of compensation to customers. In this study, a pioneering approach based on the concept of shadow prices is proposed to determine the compensation that customers should receive for unplanned water interruptions. The Chilean water industry was selected as a case study because there is an ongoing policy discussion between the use of penalties or compensation as an incentive to prevent water supply interruptions. The estimated results indicate that for 2014, the value of comp…
Measuring the CO2 shadow price for wastewater treatment: A directional distance function approach
2015
Abstract The estimation of the value of carbon emissions has become a major research and policy topic since the establishment of the Kyoto Protocol. The shadow price of CO2 provides information about the marginal abatement cost of this pollutant. It is an essential element in guiding environmental policy issues, since the CO2 shadow price can be used when fixing carbon tax rates, in environmental cost-benefit analysis and in ascertaining an initial market price for a trading system. The water industry could play an important role in the reduction of greenhouse gas (GHG) emissions. This paper estimates the shadow price of CO2 for a sample of wastewater treatment plants (WWTPs), using a param…
Energy intensity of treating drinking water: Understanding the influence of factors
2017
Abstract To provide safe drinking water to urban populations, raw water must be treated in drinking water treatment plants, which are energy-intensive facilities. Previous studies have assessed energy intensity (EI: unit of energy required per unit of treated water) of conventional drinking water treatment plants, but they ignored variations related to water treatment trains. By modeling 179 facilities of four water treatment trains, we explored factors potentially affecting energy intensity, such as removal efficiencies of pollutants and treatment capacities of drinking water treatment plants. We also investigated the economies of scale in energy intensity of drinking water treatment plant…
Evaluating the Eco-Efficiency of Wastewater Treatment Plants: Comparison of Optimistic and Pessimistic Approaches
2020
The assessment of wastewater treatment plant (WWTP) performance has gained the interest of water utilities and water regulators. Eco-efficiency has been identified as a powerful indicator, as it integrates economic and environmental variables into a single index. Most previous studies have employed traditional data envelopment analysis (DEA) for the evaluation of WWTP eco-efficiency. However, DEA allows the selection of input and output weights for individual WWTPs for the calculation of eco-efficiency scores. To overcome this limitation, we employed the double-frontier and common set of weights methods to evaluate the eco-efficiency of a sample of 30 WWTPs in Spain. The WWTPs were ranked b…
Economic effects of the consolidation of water utilities in Japan
2014
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…
Assessing the efficiency of wastewater treatment plants: A double-bootstrap approach
2017
Abstract Benchmarking the performance of wastewater treatment plants (WWTPs) is essential for promoting their long-term sustainability. Recent research has applied data envelopment analysis (DEA) models to evaluate the efficiency of WWTPs providing a synthetic index of their performance. However, the traditional DEA is a deterministic method; therefore, regression analysis cannot be used to explore the external factors influencing efficiency scores. To overcome this limitation, in this study, a double bootstrap DEA model was used for the first time to compute the efficiency scores for a sample of WWTPs. The confidence intervals for efficiency scores were estimated for each facility. Results…
Current state of water management in Japan
2014
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…
Assessing the marginal cost of reducing greenhouse gas emissions in the English and Welsh water and sewerage industry: A parametric approach
2021
Abstract Reducing greenhouse gas (GHG) emissions involves effort from different sectors of the economy, including the water and sewerage industry. This study estimates the marginal cost of curtailing GHG emissions in the water and sewerage industry using stochastic frontier analysis techniques for a sample of ten English and Welsh water and sewerage companies over the 2010–2019 period. Results illustrated that the average marginal cost of reducing GHG emissions was 0.181 £/Kg CO2 equivalent. The marginal cost estimated notably differs across companies and over time. Findings further illustrate the impact of water companies' operating characteristics on the marginal cost of reducing carbon e…
Assessing disproportionate costs to achieve good ecological status of water bodies in a Mediterranean river basin.
2011
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…
The impact of privatization approaches on the productivity growth of the water industry: A case study of Chile
2015
Abstract The water industry faces the challenge of implementing privatization reforms. This process mainly adopts the following two approaches: the privatization of public water and sewerage services (WSS) and the privatization of water companies’ ownership. This paper investigates the impact of both privatization approaches on changes in productivity in the water industry. In doing so, the Luenberger productivity indicator (LPI) was computed for a sample of Chilean water and sewerage companies (WaSCs) for the period 1997–2013. Unlike the most commonly applied index (Malmquist productivity index), the LPI simultaneously takes into account output expansion and input contraction. The results …
Assessment of wastewater treatment alternatives for small communities: An analytic network process approach
2015
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
2013
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
2009
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…
Measuring the wastewater treatment plants productivity change: Comparison of the Luenberger and Luenberger-Hicks-Moorsteen Productivity Indicators
2019
Abstract It is essential to assess the productivity of wastewater treatment plants (WWTPs) to improve their economic and technical performance over time. In doing so, reliable indexes should be used to avoid biased conclusions leading to unsuccessful policy and managerial measures. Ratio-based indexes are typically employed, but are infeasible when any of the variables are equal or close to zero. To overcome this limitation, this paper presents the innovative approach of applying and comparing two difference-based productivity indicators, Luenberger (LPI) and Luenberger-Hicks-Moorsteen (LHMPI), to evaluate how productivity changes in a sample of WWTPs. Because the LHMPI is an additively com…
Estimating Profit, Price, and Productivity Changes in Water Industry Using Bennet-Bowley Indicator
2019
AbstractThe assessment of profit, productivity, and price change over time is valuable for regulators and companies when setting tariffs. This paper innovates by comparing profit, price, and produc...
Drivers of productivity change: a comparison of English and Welsh water only and water and sewerage companies
2021
In regulated industries, such as the water industry, it is of great significance to estimate productivity change as it helps policy makers to evaluate the effectiveness of regulatory regime and industry performance. In this paper, and for the first time, a translog input distance function was used to estimate and decompose productivity change into several components such as technical efficiency change, scale efficiency change, input-mix, and technical change. A further decomposition of technical change into neutral, output- and input-induced shifts of the frontier is provided. The above decomposition was applied to the English and Welsh water and sewerage companies and water only companies …