Please cite this article in press as: T. Velegraki, D. Mantzavinos, Solar photo-Fenton treatment of winery effluents in a pilot photocatalytic reactor, Catal. Today (2014), http://dx.doi.org/10.1016/j.cattod.2014.06.008 ARTICLE IN PRESS G Model CATTOD-9114; No. of Pages 7 Catalysis Today xxx (2014) xxx–xxx Contents lists available at ScienceDirect Catalysis Today j our na l ho me page: www.elsevier.com/locate/cattod Solar photo-Fenton treatment of winery effluents in a pilot photocatalytic reactor T. Velegraki a,∗ , D. Mantzavinos b a Department of Environmental Engineering, Technical University of Crete, Polytechneioupolis, GR-73100 Chania, Greece b Department of Chemical Engineering, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras, Greece a r t i c l e i n f o Article history: Received 17 January 2014 Received in revised form 30 May 2014 Accepted 2 June 2014 Available online xxx Keywords: Photo-Fenton Winery wastewater Experimental design Solar photocatalysis a b s t r a c t A pilot-scale solar Fenton process has been applied for the treatment of winery wastewater collected dur- ing the vinification period. The importance of the experimental variables was investigated at lab-scale experiments through the application of experimental design methodology. The pilot-scale study was con- ducted on a pilot CPC photocatalytic reactor under natural solar irradiation. The results show that at low catalyst dose (i.e. [Fe 2+ ] = 5 mg L -1 ) mineralization (i.e. ca. 50%) is dependent on the oxidant consumption (i.e. 500 mg L -1 ), irrespective of the excess oxidant present; however, shorter reaction times are required under excess H 2 O 2 , indicating higher reaction rates due to higher availability of oxidant molecules in the bulk liquid. Increasing the catalyst dose enhances the reaction rate due to higher H 2 O 2 decomposition and HO • production. This is corroborated with the lower H 2 O 2 consumption (i.e. 1270 mg L -1 ) occurring at low catalyst, signifying, however, a more effective use of the oxidant (i.e. less oxidant is required to achieve similar mineralization). © 2014 Elsevier B.V. All rights reserved. 1. Introduction Wine industry is an ever growing sector of the food indus- try worldwide. In 2011 the world wine production exceeded 26,600,000 t noting a 2.9% increase compared to the respective pro- duction of 2008 [1]. Wine industry has traditionally been subject to a lesser amount of regulatory attention when compared to other industries e.g. chemicals and mining, with obvious environmen- tal impacts; however, there are several environmental issues with which wine producers have to contend [2,3], as the quality of their product is directly linked to the qualitative characteristics of the raw materials (i.e. grapes), which in turn reflect to the soil and water quality of viticulture practices. Wine making is accompanied by various processes that com- mence immediately after grape harvesting; destemming, crushing and primary (alcoholic) fermentation are followed by cold stabi- lization and secondary (malolactic) fermentation at which point the wine is ready to be bottled for further maturation or marketing purposes [4]. All the aforementioned processes require the use of high volumes of water for washing activities i.e. floor washing from ∗ Corresponding author. Tel.: +30 28210 37731; fax: +30 28210 37857. E-mail addresses: thvelegraki@gmail.com, theodora.velegraki@enveng.tuc.gr (T. Velegraki). accidental spills of grape juice and/or wine, equipment cleaning, as well as fermentation tank and bottle rinsing; a rough estimate is that for each liter of wine produced, about 1.5 L of wastewater is generated alongside. The main organic content of winery wastewater (WWW) com- prises of soluble sugars (fructose and glucose), various organic acids (tartaric, lactic and acetic), alcohols (glycerol and ethanol) and high- molecular-weight compounds, such as esters, polyphenols, tannins and lignin [5,6]. The presence of inorganic ions (i.e. potassium and sodium, with low levels of calcium and magnesium) is mainly owed to the use of cleaning agents, stabilizers and/or pesticide residues [7–9]. The precise composition, however, is extremely difficult to assess, as WWW is subject to seasonal variations in both volume and quality (e.g. vintage and non-vintage periods) while also adopts its spe- cific characteristics due to differences in vinification processes and techniques, grape varietal and amounts of water that each winery uses; in this context, COD, BOD 5 and pH values have been reported to range from 320 to 296,000 mg L -1 , 125 to 130,000 mg L -1 and 3 to 12, respectively [5,8,10–14]. As the main volume (>90%) of WWW is produced during the harvesting period, (i.e. contains a major fraction of highly biodegradable compounds such as sugars), most studies address the issue of WWW treatment by employing biological processes either as single treatment or integrated with a physicochemical http://dx.doi.org/10.1016/j.cattod.2014.06.008 0920-5861/© 2014 Elsevier B.V. All rights reserved.