Background The demand for water is increasing as a result of demographic and industrial growth. Demand for higher water quality is also increasing due to higher living standards and more stringent health and environmental regulations. Nevertheless, chronic water shortages are being suffered in many countries across the world and low water quality sources need to be considered in order to fill the water demand as alternative. Additionally,, more frequent and prolonged droughts are expected due to the effects of climate change, as have often happened in the Barcelona region and in other areas of the Mediterranean basin. For this reason, innovative and robust treatments for drinking water production need to be developed and demonstrated. In light of such water scarcity, water managers have considered a range of means of safeguarding water supply, while at the same time meeting new legislative requirements. Severe droughts and the potential impact of global climate change could lead to a decrease of quality in the water sources. On the other hand, regulations related to drinking water quality are becoming more and more stringent in order to avoid sanitary problems. The use of reverse osmosis (RO) membranes is emerging as a key technology for treating water, due to the high water quality produced. RO membranes have proven to be effective for the treatment of low quality river water, and relevant knowledge has been gathered through several European initiatives. However, pre-treatment units for RO need to be carefully assessed with regards to water losses and environmental impacts. The conventional pre-treatment for RO at a drinking water treatment plant’s water treatment processor (WTP) usually consists of dioxichlorination, coagulation-flocculation, settling and sand filtration. The feed water of the RO membranes is of high quality but the current conventional pre-treatment presents some limitations mainly related to high consumption of chemicals and high raw water losses. Alternatives to conventional pre-treatments need to be demonstrated at long-term. Objectives The UFTEC project aimed to assess the technical, environmental and economic feasibility of direct ultrafiltration (UF) as pre-treatment for RO in comparison to conventional pre-treatment consisting in coagulation, flocculation, settling and sand filtration. The proposed alternative technology was expected reduce costs and environmental impacts. The specific objectives were to: Demonstrate on a pilot scale that direct UF can be an efficient alternative to conventional pre-treatment for RO at drinking water treatment plants, and thus expand the application of membrane technology in water treatment; Assess the efficiency of three different direct UF prototypes with different configurations and membrane materials for their novel application as river water pre-treatment for RO; Evaluate levels of reagent consumption and water loss by the prototypes in comparison with conventional methods; Perform a life cycle analysis and cost-benefit analysis of the new and conventional treatment technologies; and Develop adequate tools for scaling up the design and costs from prototype to full-scale plant and for adapting the conditions of the pilot plant for full-scale implementation. Results The UFTEC project constructed and tested three different UF prototypes in the drinking WTP of Sant Joan Despi (Barcelona, Spain), as alternatives to the conventional water pre-treatment phase that currently takes place. Three prototypes were constructed with different commercial membrane configurations and were designed to minimise the scaling-up risks. The prototypes were operated and monitored over two full years, with the coupled Reverse Osmosis treatment stage operating for one year. The regular monitoring of a range of parameters (linked to water quality, energy use, chemical products use, costs, etc.) provided highly valuable data and allowed the team to optimise the operation and cleaning conditions. After two years of operation, the results obtained were highly positive and indicated that the UF prototypes were efficient for obtaining suitable water quality. In addition, the cost effectiveness and environmental impacts of the prototypes were calculated and shown to reach initial expectations. The project was initially implemented on a prototype pilot scale but by the end of the project, the processes had been scaled up in order to obtain results applicable to an entire DWTP. On the whole, the project succeeded in demonstrating the technical feasibility and economic viability of direct UF pre-treatment as an alternative to the conventional pre-treatment currently used in drinking WTPs before the RO process. The direct UF membrane technologies tested during the project presented the following advantages: Reduction in the use of chemical products (e.g. coagulants and dioxichlorination) but with a similar production yield (89-97%); Increment of water treatment availability, being able to operate independently of feed water fluctuations; Improvement in pre-treated water quality (in particular regarding fouling factor and microbiological parameters); The potential for a reduction in the space required (depending on the design).Such lifecycle analysis demonstrated that the environmental impact in both pre-treatments (measured as ‘Global Warming Potential’ – GWP) depended on operational conditions and were included in a similar data range (0.072 to 0.184k of CO2/m3 water produced for the UF technologies). In general, the environmental impact was found to be slightly higher for the UF technology, due its higher energy requirements. Energy consumption was found to be the main impact, while chemical consumption has a lower relevance. But the analysis did not take into account the amount of sludge generated, which is lower than in the conventional pre-treatment scheme. If this factor was included in the impact assessment, it would lower the overall impact of the UF technology compared to the conventional one. In all the difference is not so significant but the UF filtration presents other many advantages. In addition, other factors than GWP are important, which can justify the use of UF technology (such as, water quality and water availability adequate for subsequent RO treatment). Furthermore, the treatment scheme proposed (direct UF followed by RO) was assessed for a challenging water source – the Llobregat River – which presents a high variability in water quality, and a general low river quality (mainly due to salt contents) and quantity (due to climatic conditions). Since the project technology was found to be viable in such severe conditions, it follows that it should be applicable almost anywhere in Europe, by adapting the prototypes configurations to the specific conditions of each site (feed water quality and quantity, space available, etc.) – either in new WTPs or in upgraded plants. In can be concluded that the project technology has a great potential for application on an industrial scale. The transferability of results was further supported in the project’s use of commercial membranes, identifying their optimal performance and advantage for each water source condition. This also enhanced the acceptance of the final users of this technology, the three suppliers. Each membrane tested has its own set of characteristics and might be the most suitable depending on the economic purpose, environmental priorities and water conditions. In the long-term, it is expected that the number of installations using direct UF followed by RO will increase, towards a wide application of the project treatment scheme, this way increasing the sustainability of the future DWTPs. The use of direct UF technology (usually used for desalination and industrial applications) to replace conventional pre-treatment processes for drinking water is totally innovative, which makes this project a benchmark in the field of ultrafiltration for drinking water treatment in the EU. The overall cost of the UF technology is higher than the conventional treatment: the cost of the UF pre-treatment using the project prototypes varied between €0.076 and 0.152/m3 of water produced, while conventional treatment cost was found to be about €0.058/m3 water. But the technology was found to be especially costly effective for the reduction of fouling indexes (SDI and MFI), which makes it valuable for pre-treatment RO stages in challenging surface waters. It are not economically advantageous for the other criteria, but can still meet all the basic requirements of water pre-treatment. UF therefore is economically beneficial depending on the most important criteria that need to be met. The cost also varies according to the prototype specifications. Direct UF will need to be further studied and optimised in the near future, in order to further reduce the environmental impact and make it more attractive economically. Excellent coordination and communication lifted the visibility of the project and gave it ‘prestige’ at EU level. The technical final report was of a high standard. At the end of the project, several design engineering companies and drinking WTPs operators expressed interest in the project technology and have contacted the beneficiaries. As a result, the beneficiaries started offering direct UF technology as an alternative to conventional pre-treatments, based on the reliability and advantages demonstrated during the project. Direct UF is also proposed for upgrading of WTPs in order to improve their technical and environmental performance (e.g. reduce the water losses, increase the pre-treated water quality produced, etc.). This is a major outcome of the project and ensures its continuity. It also paves the way for the development of more stringent legislation in the future and the way to meet the challenge of increasing water demand. At the Sant Joan Despí drinking WTP, the project results will be considered in future upgrades of the plant. Finally, further tests focusing on the evaluation of alternative submerged low cost membranes using the SGAB prototype are under discussion. The objective of the tests would be to identify new membranes to replace the existing ones, in order to further reduce the economic impact of the UF process, which would in turn promote the widespread application of the UF technology in drinking WTPs. The UFTEC project was presented to the IWA Project Innovation Awards (PIA) 2014 a prestigious global competition which recognises and celebrates innovation and excellence in water engineering projects around the world. Further information on the project can be found in the project's layman report (see "Read more" section).