title: Chemical oxygen demand reduction in coffee wastewater through chemical flocculation and advanced oxidation processes.
abstract: The removal of the natural organic matter present in coffee processing wastewater through chemical coagulation-flocculation and advanced oxidation processes (AOP) had been studied. The effectiveness of the removal of natural organic matter using commercial flocculants and UV/H2O2, UV/O3 and UV/H2O2/O3 processes was determined under acidic conditions. For each of these processes, different operational conditions were explored to optimize the treatment efficiency of the coffee wastewater. Coffee wastewater is characterized by a high chemical oxygen demand (COD) and low total suspended solids. The outcomes of coffee wastewater treatment using coagulation-flocculation and photodegradation processes were assessed in terms of reduction of COD, color, and turbidity. It was found that a reduction in COD of 67% could be realized when the coffee wastewater was treated by chemical coagulation-flocculation with lime and coagulant T-1. When coffee wastewater was treated by coagulation-flocculation in combination with UV/H2O2, a COD reduction of 86% was achieved, although only after prolonged UV irradiation. Of the three advanced oxidation processes considered, UV/H2O2, UV/O3 and UV/H2O2/O3, we found that the treatment with UV/H2O2/O3 was the most effective, with an efficiency of color, turbidity and further COD removal of 87%, when applied to the flocculated coffee wastewater.
authors.affiliation: Postgrade in Environmental Sciences, Center of Chemistry, Institute of Science, Meriterious University Autonomous of Puebla. P.O. Box 1613, C. P. 72000, Puebla, Mexico. tzayasp@hotmail.com
authors.forename: Teresa
authors.initials: T
authors.lastname: Zayas Pérez
authors.forename: Gunther
authors.initials: G
authors.lastname: Geissler
authors.forename: Fernando
authors.initials: F
authors.lastname: Hernandez
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry; D040503:Coffea; D005427:Flocculation; D019649:Food Industry; D006861:Hydrogen Peroxide / Q000737:chemistry; D007220:Industrial Waste; D016877:Oxidants / Q000737:chemistry*; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D010126:Ozone / Q000737:chemistry; D014466:Ultraviolet Rays; D014865:Waste Disposal, Fluid / Q000379:methods; D014873:Water Pollutants / Q000737:chemistry* / Q000528:radiation effects*
chemical_list: D017610:Calcium Compounds; D007220:Industrial Waste; D016877:Oxidants; D010087:Oxides; D014873:Water Pollutants; D010126:Ozone; D006861:Hydrogen Peroxide; C016538:lime; D010100:Oxygen