Background The growing problem of scarcity of water of sufficient quality affects around 70% of European citizens, especially those in southern countries where the impact of climate change is greater. In fact, some are living in extreme situations with increased frequency of flooding or drought. As the cost of energy production increases, so too does the cost of water. As a result, EU policy-makers and institutions are committed to developing new strategies that encourage efficient use of water resources. The European Innovation Partnership on Water, (EIP Water), created in 2012, has identified priority areas in order to overcome the main environmental problems related to water: scarcity, unsustainable wastewater treatment and the impact of untreated wastewater on water bodies. Objectives The LIFE SIAMEC project will demonstrate the anaerobic treatment of municipal and industrial wastewater at ambient temperature in European climates in order to obtain a technology that consumes less energy, produces less biomass and has a lower integrated footprint for wastewater reclamation. This technology will overcome the main drawbacks associated with anaerobic wastewater treatment at low temperature – namely, greenhouse gas emissions and nitrogen removal – since the dissolved methane present in the effluent is used as a source of carbon for denitrification in both a membrane and a non-membrane based post-treatment. The project will demonstrate the technical feasibility of applying basic and advanced reclamation processes to the effluents of both prototypes for agricultural, industrial, environmental and urban water re-use while reducing associated costs and environmental impacts in comparison to the conventional wastewater treatment schemes currently applied. Expected results: 50% reduction of the energy consumption in comparison with conventional activated sludge systems; 30% reduction of the energy consumption in comparison with conventional systems followed by tertiary treatment (UV) commonly used for municipal wastewater reclamation; Recovery of 1-2 Kwh/m3 treated wastewater; 50% reduction of sludge production; 80% reduction of total nitrogen without external carbon source addition and thus minimal treatment costs; 90% reduction of methane emissions associated with anaerobic treatment at ambient temperature; Demonstration of the feasibility of a non-membrane based post-treatment for anaerobically treated wastewater at ambient temperature in European climates; Verification of biomass retention and nitrogen removal capabilities; Establishment of most appropriate treatment scheme to be applied depending on the required water quality; Quantification of the economic and environmental benefits of the proposed treatment scheme; Identification of the optimal operational strategies and modelling of the process; Identification of the main technical and economic motivations and constraints for the implementation of the proposed technology as an upgrading technology for WWTPs in the EU; Determination of the potential transferability of the technology to other European regions and/or climate conditions as well as different wastewater profiles. Besides Mediterranean and Atlantic regions, many people live in a geographical area that is under the threat of periods of water scarcity. Moreover, municipal and industrial wastewaters may be different across industrial regions and cities in Europe; Collaboration for the achievement of EU challenges in the water sector, through policy making, technical solutions, management of solutions and social responsibility; and Fostering water re-use initiatives, through dissemination of results and knowledge transfer to end users identified through the project.