title: Sequential use of bentonites and solar photocatalysis to treat winery wastewater.
abstract: The sequential use of low-cost adsorbent bentonites and solar photocatalysis to treat winery wastewater has been studied. Three commercial sodium-bentonites (MB-M, MB-G, and MB-P) and one calcium-bentonite (Bengel) were characterized and used in this study. These clay materials were useful to totally remove turbidity (90-100%) and, to a lesser extent, color, polyphenols (PPh), and soluble chemical oxygen demand (CODS) from winery wastewater. Both surface area and cation exchange capacity (CEC) of bentonite had a positive impact on treatment efficiency. The effect of pH on turbidity removal by bentonites was studied in the 3.5-12 pH range. The bentonites were capable of greatly removing turbidity from winery wastewater at pH 3.5-5.5, but removal efficiency decreased with pH increase beyond this range. Settling characteristics (i.e., sludge volume index (SVI) and settling rate) of bentonites were also studied. Best settling properties were observed for bentonite doses around 0.5 g/L. The reuse of bentonite for winery wastewater treatment was found not to be advisable as the turbidity and PPh removal efficiencies decreased with successive uses. The resulting wastewater after bentonite treatment was exposed to solar radiation at oxic conditions in the presence of Fe(III) and Fe(III)/H2O2 catalysts. Significant reductions of COD, total organic carbon (TOC), and PPh were achieved by these solar photocatalytic processes.
authors.affiliation: Departamento de Ingeniería Química y Química Física, Universidad de Extremadura, 06071 Badajoz, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Rodríguez
authors.forename: Gracia
authors.initials: G
authors.lastname: Márquez
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Carpintero
authors.forename: Fernando J
authors.initials: FJ
authors.lastname: Beltrán
authors.forename: Pedro
authors.initials: P
authors.lastname: Alvarez
mesh_terms: D001546:Bentonite / Q000737:chemistry*; D002384:Catalysis; D006861:Hydrogen Peroxide / Q000737:chemistry; D007220:Industrial Waste / Q000032:analysis* / Q000191:economics; D013472:Sunlight; D014865:Waste Disposal, Fluid / Q000191:economics / Q000379:methods*; D018508:Water Purification / Q000191:economics / Q000379:methods*
chemical_list: D007220:Industrial Waste; D001546:Bentonite; D006861:Hydrogen Peroxide