This paper explores the potential of integrated management of neighboring wastewater treatment plants (WWTPs). The novelty lies in the integration of environmental aspects, with the application of life cycle assessment (LCA) methodology, together with economic criteria for the selection of best alternatives. A case study illustrates how the connection of neighboring wastewater systems by constructing an extra pipeline provides positive results in the economic assessment, and in the majority of the LCA categories used in the global environmental assessment. The consideration of local environmental constraints suggests that the usage of the connection should be limited to periods when the minimum ecological flow in the river section between the discharges of the two WWTPs is maintained. In this particular case, the scenario that promotes the usage of the connection between the two WWTPs (but with some restrictions in dry weather periods) is preferred because it provides cost savings of 45,053€·year-1 and satisfies environmental criteria. A scenario analysis has been conducted to evaluate the influence of the pipe length on both economic and environmental aspects and the influence of individual cost terms on the economic assessment

The authors would like to thank Consorci per la Defensa de la Conca del Riu Bes os (CDCRB) (especially A. Freix o, C. Turon and J. Arr aez) for providing the case-study and the required data as well as the Spanish Ministry of Science and Innovation for funding (CTM-2009-13018 and RYC-2013-14595), and the European Union (ECOTECH-SUDOE Project SOE2/P2/E377, Marie Curie Career Integration Grant PCIG9-GA-2011-293535 and Marie Curie SANITAS ITN Project GA 289193). Serni Morera's FI scholarship and Voltes, S.L.U., for the technical advice and information for the inventory of the pipeline construction provided, are also acknowledged. LEQUIA and ICRA were recognised as consolidated research groups by the Catalan Government with codes 2014-SGR-1168 and 2014-SGR-291, respectively