Background Textile industries use vast volumes of different mostly synthetic dyes. Synthetic dyes can pose many environmental problems, due to the abundance of hazardous chemicals (alkalis, acids, solvents, etc.) that are associated with these dyes. Large volumes of hazardous waste and wastewater are produced from many textile processes that use synthetic dyes. According to the World Bank, dyeing industries produce 20% of the industrial polluted water. In fact, dyeing 1 kg of cotton uses around 100 l of water Natural dyes, however, tend to be clinically safer than synthetic dyes because they do not normally produce hazardous risks and possess better biodegradable characteristics. Obtaining natural dyes is more complex and also implies more time and resources (1kg require around 1230 ha of farmland), making them an uncompetitive option. Objectives The main objective of the LIFE SEACOLORS project is to demonstrate and validate a new process for obtaining natural dyes from a sustainable and renewable source – algae. The project will also test and assess the possibilities of using these new natural dyes to replace synthetic dyes in the textile industry. Environmental benefits from biodegradable dyes are anticipated, including less polluted wastewater and reduced water purification demand. Such benefits will help reach the goals of EU legislation covering wastewater (e.g. Directive 2008/105/CE and the REACH regulation). The project will achieve its aims by: selecting algae with high dye capacity and potential for mass cultivation; improving the algae’s dye content through optimising their growth conditions; studying the extraction conditions to optimise the amount of dye obtained; comparing different dyeing process and auxiliary substances needed to obtain satisfactory results; and assessing the ‘fastness’ of the obtained natural dyes compared with synthetic dyes. In order to substitute synthetics dyes, the new solution must be able to provide a wide range of colours, and consequently a high variety of shades. To fulfil this aim within the project timespan, the consortium will focus on a mixture of three colours (red, yellow and blue) and from these develop other colours in the chromatic scale. Expected results: A selection of algae species (25 different strains of microalgae/cyanobacteria and 10 different species of macroalgae) with potentially high dyeing properties; Optimal procedures for growing the algae, increasing their dyes production and extracting their natural pigments for use as alternatives to synthetic textile dies; A new dyeing process using the new products tested and validated at a semi-industrial level; Legislated dilution of 1/40 of the targeted pollutants without the need for further purification; Lower final cost of the process due to savings created from reduced wastewater purification costs (despite the higher cost of producing the new natural dye); Viability of using the new dye production process in other sectors, such as food, cosmetics and fertilisers, assessed.