Background The Portuguese government aimed to implement wastewater treatment (WWT) systems in 90% of the country by 2006 (only 55% of the country was covered in 1999). A frequent problem encountered was the fact that many local councils in charge of domestic wastewater treatment do not have the technical and financial capacity to take responsibility for several treatment units within their region. A new model was therefore needed to help municipalities deal with managing additional WWT capacity effectively. Objectives The project aimed to demonstrate new technologies for recycling water from Municipal Waste Water Treatment Plants (WWTP) and to improve the environmental sustainability of the Mondego Lower Basin and Estuary. Capacity building featured strongly in the project goals and activities planned included: establishing systems to monitor data from WWTPs within the Mondego River catchment; designing, building and testing a prototype for remote centralised monitoring and supervision of the WWTP main physiological parameters (pH, temperature, dissolvent oxygen, carbon dioxide and hydraulic data measurements); and implementing a Cleaning-Hygienisation-Tertiary system, using a new Submerged Membrane bioreactor system and microalgae reactor. Findings from the demonstration projects were to be collated and disseminated via training actions for local municipalities. Results The Mondego project achieved all its objectives and successfully developed, built and tested the innovative technologies as prototypes. These included a monitoring prototype, control prototype, a Submerged Membrane Bio-Reactor (SMBR) prototype and a microalgae photoreactor prototype. Prototype modules were integrated and installed at the main WWTP in Águas da Figueira, where the new technologies were used for project studies which demonstrated the following results: Improved overall WWTP functions - reducing requirements for amplification or modification of existing plants to comply with new standards and legislation; An ability to produce effluent of equivalent and improved quality compared to large sedimentary tanks; Good flexibility to deal with different seasonal loads and with a reduced formation of biomass; Enhanced efficiency by implementation of real time, 24 hours/day alarms, and auto-correction equipment controlling WWTP operation to prevent activity cessation, defective running or occasional malfunctioning; Lower energy consumption levels; Improved effluent recycling capacities - allowing reuse of wastewater for agriculture, municipal garden watering, street washing, etc. Further water cleansing, using biomembranes and photoreactor technologies, offer opportunities to achieve drinking water quality; and Improved and effective coverage of residual water treatment - decreasing persistent and dispersed pollutants, such as heavy metals and nitrates, in a sensitive zone (included within NATURA 2000) of the Mondego basin.Additional environmental benefits available from the LIFE project innovations include eased pressures on ground water sources and CO2 fixation by microalgae that can help fight climate changes. The technologies developed during the project are considered to have strong transferability and compare favourably to alternatives from a long term economic perspective.