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.