Background Olive production is a significant economic sector in southern Member States, especially in Spain, Italy, Greece and Portugal. However, the extraction process involved in olive oil production generates non-biodegradable phytotoxic waste, and therefore poses significant pollution risks. Despite the introduction in the 1990s of improved separation systems that reduce both water use and the quantities of liquid residues produced, the problems of waste toxicity, high energy consumption and the disposal of final residues remain. Objectives The OLIVEWASTE project’s main goal was to demonstrate the environmental advantages, as well as the economic and technical viability, of a new system for treating waste from olive oil production. This innovation was based on a three-step procedure comprising the separation of solid residues, followed by evaporation and condensation processes, before a final water treatment. After developing prototypes for each of these stages, a pilot plant was constructed which would be able to convert the waste into liquid and solid fertilisers, plus provide a safe source of irrigation water. The pilot plant was built primarily to process waste from the ‘3-Phase’ olive oil production process. Project staff also identified options for adapting the new treatment system for wastes generated by ‘2-Phase’ production processes. This would involve either using mechanical drying using a 3-phase decanter, or mills could carry out the second oil extraction using a 3-phases system instead of 2-phases. Results Project results were positive and the LIFE-funded pilot plant successfully treated all types of olive oil production waste into useful by-products that are valuable for future agricultural use. Total estimated cost of waste treatment using the project technology, based on the data obtained during the project, is €4.42 per tonne of olives. Benefits were estimated to be as high as €6.53 per tonne of olives of olive, due to income streams anticipated from sale of solid and liquid fertilisers. These figures are estimates and the project acknowledges that further work is required to determine the optimal parameters for fertiliser quality. Key environmental benefits of the new system include its low water consumption requirements, compared to conventional approaches. Waste water is cleaned and reused, either within the plant or for irrigation, and this reduces the need for evaporation lagoons. Water re-use remains a high political priority for most important olive oil production regions (Southern EU Countries). Another important commercial advantage of the new system is its ability to treat large quantities of all types of waste simultaneously in a short time. Waste ‘cake’ also has a relatively low humidity which implies a reduction in associated transport costs. Overall the new system was found to have a relatively high energy consumption but options for offsetting this were identified by generating renewable power from using the cake as bio-fuel. The OLIVEWASTE project has a high demonstration value since the treatment system was tested on a semi-industrial scale, indicating that a standard plant could treat 15 000 l of waste fluid per hour. The scale of the investment required leads the project team to believe that large oil processing companies, like those in Spain, could justify building their own waste treatments plants using the new technology. Communal plants would be more viable in areas containing networks of smaller olive oil producers, such as in Italy, Greece, and Portugal. Socio-economic benefits will be gained by addressing odour problems related to disposal lagoons. These affect the daily life of locals and also tourism activity. Further work is foreseen to help sustain and strengthen the LIFE project’s initial outcomes. More research will be undertaken to improve the quality of fertiliser by-products and awareness raising will be continued among olive oil producers to increase uptake of the new technology. Legislative and/or financial incentives are considered useful by the project team to help broaden application of their new waste management system and this could considerably reduce the olive oil industry’s environmental footprint. Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).