Anaerobic Digestion of Vinasse for the Production Of Methane in the Sugar Cane Distillery

摘要

The expansion and diversification of new alternative energy sources in a sustainable and efficient way figures strongly among the major concerns of the industrialized world. Recent energy supply crunches and price spikes have propelled ethanol as an alternative transportation fuel. Ethanol derived from renewable sources has brought a host of challenges along with opportunities to the sugar industry. Providing cost effective systems for the treatment, conservation and recycling of water and energy resources is definitively one of these challenges. rnVinasse, the liquid residue left in the distillation of ethanol from sugar cane derivates, frequently poses serious disposal challenges as evidenced by its high biochemical oxygen demand (BOD). On an average basis, 12 cu ft of vinasse per cu ft of ethanol are produced in the distillery, with a BOD load ranging from 1.06 to 3.12 lb/cu ft of vinasse (17,000 to 50,000 mg/1). A study was carried out to assess the anaerobic digestion of vinasse for the production of methane. The purpose of this study was to gather enough data for subsequent evaluation of the technical feasibility of the process. The anaerobic digestion featured a complete mix reactor (digester) utilizing a two steps acid and methane-producing bacteria (thermophilic). Calculations data included temperature of 40 ℃ (104 °F) and mean cell residence time of 10 days. Results of a mathematical anaerobic digestion model (MADM) built to evaluate the system indicated that a 90% BOD reduction in the vinasse could be obtained by anaerobic digestion in a sugarcane-to-ethanol distillery producing 1,500,000 cu ft per year of ethanol (38,000,0001 per year).