Recovery of sugarcane vinasse by microbial pathway: An integral approach

Abstract

Vinasse is the main effluent generated from alcohol distilleries, with an average volume that ranged from 10 to 18 l of vinasse per l of ethyl alcohol produced. Vinasse composition varies according to the raw material and equipment utilized in the process of alcohol production. However, the effluent is a brown liquid which contains basically water (93%) as well as organic solids and minerals (7%). Vinasse is usually characterized by a low pH (4.5 to 5.5), a high salts content, and a chemical oxygen demand (COD) around 80,000 to 100,000 mg l−1 while the biochemical oxygen demand (BOD) often range from 30 to 70% of the COD. Sugarcane production has a significant economic and social importance in the Tucumán province since it is one of its main agro-industrial activities. The vinasse is often released into the main canal that runs through to the sugar factory and meanders into the secondary channels around the cane fields. Aquatic ecosystems are the main receptors for toxic substances from industrial and agricultural activities. These ecosystems are able to assimilate and even neutralize the toxic substances as long as they do not exceed the depuration capacity of the water. Because of the chemical composition of vinasse, it is been observed that its continuous disposal in the waterway could result in the depletion of the oxygen supply and the accumulation of very high levels of heavy metals and other toxins, causing the canal to become not habitable for aquatic life. Finally, its detrimental impact could extend to human life. The vinasse recovery by microbial pathways is feasible due to the high concentration of biodegradable organic carbon. This chapter, consider an approach based on considering to the vinasse as a byproduct of the sugar-alcohol industry. The approach aims at the integral use of vinasse as it is intended to take advantage of both the microbial biomass and the supernatant generated from the raw effluent for use it as soil fertilizer or for the recovery of microbial product from them.