0000000000222409
AUTHOR
Trinidad Gómez
Eco-efficiency assessment of wastewater treatment plants using a weighted Russell directional distance model
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…
Measuring the eco-efficiency of wastewater treatment plants under data uncertainty
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…
Dynamic goal programming synthetic indicator: an application for water companies sustainability assessment
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
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…
Project portfolio selection and planning with fuzzy constraints
Abstract Selecting a project portfolio is a complex process involving many factors and considerations from the time it is proposed to the time the project portfolio is finally selected. Given that making a good selection is of crucial importance, it is essential to develop well-founded mathematical models to lead the organization to its final goal. To achieve this, such models have to reflect as closely as possible both the real situation of the organization as well as its targets and preferences. However, since the process of selecting and implementing project portfolios occurs in real environments and not in laboratories, uncertainty and a lack of knowledge regarding some data is always a…
Assessing the sustainability of small wastewater treatment systems: A composite indicator approach
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 …
Eco-efficiency assessment of municipal solid waste services: Influence of exogenous variables.
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
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…
Assessing the quality of service to customers provided by water utilities: A synthetic index approach
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 …
Evaluating the Eco-Efficiency of Wastewater Treatment Plants: Comparison of Optimistic and Pessimistic Approaches
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…
Assessing the efficiency of wastewater treatment plants: A double-bootstrap approach
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…
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…
Measuring the wastewater treatment plants productivity change: Comparison of the Luenberger and Luenberger-Hicks-Moorsteen Productivity Indicators
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…