Francesc Hernández-Sancho

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 that plant size, quantity of organic matter removed, and type of bioreactor aeration were significant variables in explaining energy efficiency differences. In contrast, age of the plant was not a determining factor in energy consumption. Lastly, we quantified the potential savings, both in economic terms and in terms of CO(2) emissions, that could be expected from an improvement in energy efficiency of WWTPs.

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 effluent for environmental purposes. Internal benefit analyses indicated that only a proportion of projects were economically viable, while when external benefits are incorporated all projects were economically viable. In conclusion, the economic feasibility assessments of water-reuse projects should quantitatively evaluate economic, environmental and resource availability.

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. Nevertheless, the valuation of these benefits is necessary to justify a suitable investment policy and a limited number of studies exist on the subject of the economic valuation of environmental benefits. In this paper, we propose a methodology based on the estimation of shadow prices for the pollutants removed in a treatment process. This value represents the environmental benefit (avoided cost) associated with undischarged pollution. This is a pioneering approach to the economic valuation of wastewater treatment. The comparison of these benefits with the internal costs of the treatment process will provide a useful indicator for the feasibility of wastewater treatment projects.

Economic Feasibility Study for Phosphorus Recovery Processes

Phosphorus recovery from wastewater has become a necessity for sustainable development because phosphorus is a non-renewable essential resource, and its discharge into the environment causes serious negative impacts. There are no economic incentives for the implementation of phosphorus recovery technologies because the selling price of rock phosphate is lower than phosphorus recovered from sewage. The methodologies used to determine the feasibility of such projects are usually focused on internal costs without considering environmental externalities. This article shows a methodology to assess the economic feasibility of wastewater phosphorus recovery projects that takes into account internal and external impacts. The shadow price of phosphorus is estimated using the directional distance function to measure the environmental benefits obtained by preventing the discharge of phosphorus into the environment. The economic feasibility analysis taking into account the environmental benefits shows that the phosphorus recovery is viable not only from sustainable development but also from an economic point of view.

Efficiency and Environmental Regulation

This paper proposes an extension of the enhancedefficiency indices of Färe, Grosskopf, Lovell andPasurka (1989) that considers undesirable outputsasymmetrically by assuming that firms can freelydispose of some undesirable productions, but areduction of other bad outputs generates a cost interms of desirable outputs. This methodologicalapproach is used to analyse the relative efficiency ofa sample of Spanish producers of wooden goods andfurnishings whose production process generates fourdifferent wastes. We obtain efficiency indices thatserve to measure the impact on firm performance inseveral scenarios related to environmental regulationsaimed to reduce the production of wastes. Whenenvironmental regulations are assumed, it is foundthat firms would have to sacrifice important amountsof potential desirable output in order to reallocateinputs into waste reduction. Secondly, we find thatfirms associated with a Technological Institute aswell as firms located at a marshallian type industrialdistrict are likely to be less affected byregulations.

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 between a conventional labour productivity index and an extended productivity index are also statistically related to firms characteristics such as size, previous investments in cleaner technologies and affiliation to a Technological Institute.

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 the vast amount of knowledge from treatment technologies contained in the EDSS was applied in nine scenarios comprising different wastewater characteristics and reuse options. Hence, a useful economic feasibility indicator is obtained for each technology including internal and external costs and, for the first time, benefits associated with the environmental damage avoided. This new methodology proved to be crucial for supporting the decision process, contributing to improve the sustainability of new treatment facilities and allows the selection of the most feasible technologies of a wide set of possibilities.

Benchmarking in wastewater treatment plants: a tool to save operational costs

The economics of wastewater management and treatment is the subject of growing interest by water agencies and wastewater treatment plant (WWTP) operators. Benchmarking procedures are useful tools to assess the performance of these facilities and help identify best practices. To estimate the efficiency scores for each input involved in the operation of WWTPs, a non-radial data envelopment analysis model has been applied to a sample of Spanish WWTPs. The great advantage of this methodology is that it enables the identification of cost items on which to act to increase the efficiency at plant level. In the second stage, variables influencing efficiency scores have been identified. This analysis helps improve the understanding of how individual scores of efficiency and operating variables are related. It is shown that some factors do not affect all cost items—thus illustrating that an increase in global efficiency would not produce a reduction in all cost items. The benchmarking methodology and empirical application developed in this article could be very useful for improving the management of WWTPs and contribute to save operational costs.

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 is very stable since constructed wetlands are almost always placed in the first position. This paper showed that ANP analysis is suitable to deal with complex decision-making problems, such as the selection of the most appropriate WWT system contributing to better understand the multiple interdependences among elements involved in the assessment.

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 these pollutants into water bodies. For the first time the shadow prices of 5 PPCPs which are ethynilestradiol, sulfamethoxazole, diclofenac, tonalide and galaxolide from treated effluent using a pilot-scale ozonation reactor have been estimated. From non-sensitive areas their values are -73.73; -34.95; -42.20; -10.98; and -8.67 respectively and expressed in €/kg. They represent a proxy to the economic value of the environmental benefits arisen from undischarged pollutants. This paper contributes to value the environmental benefits of implementing post-treatment processes aimed to achieve the quality standards required by the Priority Substances Directive.