Sugarcane vinasse processing in combined systems: two-phase anaerobic digestion and evaporation

Abstract

The correct management of sugarcane vinasse in the sugar-alcohol agroindustry is a fundamental step towards the recovery of resources (water, energy, and nutrients) and the mitigation of environmental impacts. Anaerobic Digestion (AD) is a treatment system widely recognized for its efficiency in removing organic compounds and for its potential to produce biogas, especially methane. The operation of anaerobic reactors in two stages (acidogenic and methanogenic) has numerous advantages to the methanogenic process, with emphasis on the reduction of organic shocks caused by the imbalance between the microbial communities that produce and consume acids, and the reduction/elimination of competition between methanogenic and sulfidogenic microorganisms for common substrates. Recent studies have proven the feasibility of sulfate reduction in the acidogenic stage, opening perspectives to answer important questions regarding the alkalinity generation potential and the understanding of the sulfide stripping mechanisms to favor the methane production in biorefineries. In addition to the energy potential, the recovery of water from the concentration of vinasse is an advantageous alternative for the sugar-alcohol sector in taking actions to reduce water uptake and expand its reuse in production units. Thus, the objective of this work is to assess the feasibility and efficiency of a sequential model for processing sugarcane vinasse, capable of enhancing the recovery of energy, water, and nutrients in the ethanol production chain. (AU)