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.     

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 (m³) and the other on eutrophication reduction (kg PO₄³⁻ removed) were used to further determine sustainability. A correlation between legal requirements and technologies used to achieve them was found: Organic matter removal plants were found to be less costly both in environmental and economic terms if volume was used as the functional unit, while more demanding typologies such as reuse plants showed a trade-off between lower EP and higher cost and GWP; however, this is overcome if the second FU is used instead, proving the sustainability of these options and that this FU better reflects the objectives of a WWTP.     

Correction to: Assessment of wastewater reuse potential for irrigation in rural semi-arid areas: the case study of Punitaqui,Chile

Clean Technologies and Environmental Policy - In this mentioned article, the Author names are mistakenly have been replaced with the family name of the authors, and so the family names with the names.     

Estimation and evaluation of productivity change and its drivers in the English and Welsh water sector: a stochastic cost frontier approach

ABSTRACT

Estimating productivity change and its determinants is of great importance when measuring the performance of a firm. A true random effect cost model was employed to measure the cost efficiency of water companies in England and Wales from 1993 to 2016. Subsequently, total factor productivity change was estimated and decomposed into cost-efficiency change, technical change, scale efficiency change, output effect and residual price effect. The results indicate that the English and Welsh water industry increased its productivity over the period examined at a rate of about 2.1%, and it was influenced primarily by technical change. The price reviews appear to have a positive impact on the productivity of water-only companies during the whole period examined. In the case of water and sewerage companies, the 1994 and 1999 price reviews had a positive impact on productivity, whereas the last two price reviews had an adverse impact.     

Cost Efficiency of English and Welsh Water Companies: a Meta-Stochastic Frontier Analysis

Water Resources Management - In regulated industries it is important to identify appropriate performance benchmarks to incentivize companies’ performance. This study applies a stochastic...     

Comparative energy efficiency of wastewater treatment technologies: a synthetic index approach

Improving the energy efficiency of wastewater treatment plants (WWTPs) provides notable economic and environmental benefits to society. Several studies have benchmarked the energy performance of WWTPs, but they did not take into account for differences in the wastewater treatment technologies they used, thus obscuring their relative efficiencies in removing harmful pollutants. To overcome this shortcoming, this study assessed and compared the energy efficiencies of five wastewater treatment technologies. To do so, the metafrontier approach was used in order to account for the technological differences among plants in removing pollutants. The results evidenced that energy efficiencies for WWTPs using attached-growth processes were higher than for WWTPs using suspended-growth technologies as secondary treatment. Moreover, higher pollutant removal efficiencies associated with biological removal of nutrients compensated for the higher energy requirements of this technology, making these WWTPs more energy efficient in the removal of pollutants. The results of this study provide essential information for improving the sustainability of current WWTPs and can support decision-making in the planning of new wastewater treatment facilities.     

Assessment of the Total Factor Productivity Change in the English and Welsh Water Industry: a Färe-Primont Productivity Index Approach

The assessment of productivity change across companies and over time is of great importance for water utilities managers and regulators. In this paper, for the first time, we apply the Färe-Primont productivity index (FPI) to evaluate the productivity change for the 10 water and sewerage companies (WaSCs) and 12 water only companies (WoCs) in England and Wales during the years 2001–2008. The FPI is the only index that without price data allows making comparisons involving many firms and many periods. The results indicate that during the years 2001–2004 productivity improved which was mainly attributed to gains in efficiency whereas technical change remained constant, the exception being the year 2004. During the years 2005–2008 productivity showed a declining trend and any gains in efficiency were lost to the highly negative technical change on productivity growth. From a policy perspective, it has been illustrated the importance of using a reliable index to compute the productivity change of water companies when the performance of companies is used to set water tariffs. Finally, the decomposition of productivity change into several drivers allows water utilities and managers to identify the main factors on which they should act to improve productivity of the company.     

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

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 six 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 in regard to both investment and operation and maintenance costs. However, the effectiveness of the alternatives evaluated depends significantly on the scenarios considered, with SM the most effective in most cases. Finally, the cost-effectiveness ratio showed SM as the best cost-effective alternative. CEA provides an ecological-economic indicator useful to prioritize wastewater treatment alternatives to achieve a given objective.     

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 technologies that considers internal and external impacts. The estimation of the costs is based on the use of cost functions. To quantify the environmental benefits from wastewater treatment, the distance function methodology is proposed to estimate the shadow price of each pollutant removed in the wastewater treatment. The application of this methodological approach by decision makers enables the calculation of the true costs and benefits associated with each alternative technology. The proposed methodology is presented as a useful tool to support decision making.