RESEARCH ARTICLE Oxidation of winery wastewater by sulphate radicals: catalytic and solar photocatalytic activations Jorge Rodríguez-Chueca 1 & Carlos Amor 2 & Joana Mota 2 & Marco S. Lucas 2 & José A. Peres 2 Received: 25 April 2017 /Accepted: 2 August 2017 # Springer-Verlag GmbH Germany 2017 Abstract The treatment of winery effluents through sulphate radical-based advanced oxidation processes (SR-AOPs) driv- en by solar radiation is reported in this study. Photolytic and catalytic activations of peroxymonosulphate (PMS) and persulphate (KPS and SPS) at different pH values (4.5 and 7) were studied in the degradation of organic matter. Portugal is one of the largest wine producers in Europe. The wine making activities generate huge volume of effluents characterized by a variable volume and organic load, being their seasonal nature one of the most important drawbacks. Recently, SR-AOPs are gradually attracting attention as in situ chemical oxidation technologies, instead of hydroxyl radical AOPs (HR-AOPs). The studied concentrations are suitable to obtain notable values of organic matter degradation, with TOC removal around 50%. In general terms, no notable dif- ferences were observed between treatments at pH values 4.5 and 7. Photolytic activation of SPS with solar radiation treat- ments obtained the highest efficiency (28 and 40% of TOC removal with 1 and 50 mM, respectively, at pH 4.5) in com- parison to KPS and PMS. The addition of a transition metal as catalyst, such as Fe(II) or Co(II), increased considerably the TOC removal efficiency higher than 50%, but not in all cases. For instance, the combination KPS or PMS with Co(II) at pH 4.5 did not allow to obtain better results than photolytic acti- vation of these persulphate salts. In summary, the use of SR- AOPs could be a serious alternative as tertiary treatment for winery wastewaters. Keywords Winery wastewater . Peroxymonosulphate . Persulphate . Solar radiation; cobalt . Iron Introduction Wine making activities, such as the washing of tanks, filters and facilities, in general, generate huge amount of litres of effluents (Mosteo et al. 2006), approximately 1.3–1.5 kg of effluent per litre of wine (Lucas et al. 2010). This wastewater causes a contamination in water that may be classified as non- toxic. In most cases, the effluents are characterized by a high content of dissolved organic matter and suspended solids and a relatively acidic pH (Diez et al. 2017). Moreover, winery effluents are characterized by marked seasonal nature. These effluents are generated after the process of crushing, macera- tion, pressing, racking, fermentation and storage. Most of the Highlights • Solar photolytic activation of PMS, SPS, and KPS was studied. • Efficiency of catalytic activation of sulphate salts was assessed using Fe and Co. • No large differences were observed between treatments at pH 4.5 and neutral pH. • Sulphate radicals are a feasible technology for degrading organic matter (> 60%). • Combination of KPS or PMS with Co(II) at pH 4.5 gets worse efficiency. Responsible editor: Suresh Pillai Electronic supplementary material The online version of this article (doi:10.1007/s11356-017-9896-2) contains supplementary material, which is available to authorized users. * Jorge Rodríguez-Chueca rodriguezchueca@gmail.com * Marco S. Lucas mlucas@utad.pt 1 Department of Chemical and Environmental Technology (ESCET), Universidad Rey Juan Carlos, C/ Tulipán s/n, 28933 Mostoles, Madrid, Spain 2 Centro de Química de Vila Real, Departamento de Química, Universidade de Trás-os-Montes e Alto Douro (UTAD), 5000-801 Vila Real, Portugal Environ Sci Pollut Res DOI 10.1007/s11356-017-9896-2