Characterization and Treatment of Sugarcane Vinasse by Coagulation- Flocculation Followed by Sulfate Radical Based on Advanced Chemical Oxidation Process

Abstract

Vinasse which is a by-products of ethanol production is considered to be a serious hazards to the environment. Two sample (1 and 2) of vinasse, colored dark brown, were collected and detected to be acidic. Sample 1 and 2 were analyzed and gave 68.98 and 65.00 mg/dm3 biochemical oxygen demand (BOD), 125.77 and 200.00 mg/dm3 chemical oxygen demand (COD) and 489.6 and 480.4 mg/dm3 total organic carbon (TOC), respectively. GC-MS analysis detected the presence of phenols and carboxylic acids which also has negative effect on the environment. The detection of considerable amounts of potassium and sodium implied that vinasse could be used as a fertilizing. The removal efficiency of TOC, color and aromatic organic compounds (AOC) from vinasse was examined using coagulation-flocculation techniques. Ferric chloride was used as a coagulant. In coagulation-flocculation techniques the effects of doses and pH values on TOC, color and AOC removal were studied. The efficiency of coagulation-flocculation in removing TOC gave 65.4 % when using 10g/dm3 of Ferric chloride and near to 100% in removing of color and AOC. The acidic condition was preferred for removing TOC, AOC and color from vinasse. Persulfate (PS) and peroxymonosulfate (PMS) based advanced oxidation process (AOPs) were used as second stage to enhance the TOC removal. The effects of oxidant doses, oxidant to catalyst ratios, pH values and reaction times were studied. 69.9% and 48.6% of TOC were removed under optimum conditions of PMS and PS respectively. Overall removal of TOC from vinasse using coagulation-flocculation followed by PMS achieved 91.6% and 85.6% when using coagulation-flocculation followed by PS. Sulfate radical (SR)-AOP, however could be used as anew, promising and alternative technique for vinasse treatment.