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

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 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.