Sugarcane stillage treatment by membrane distillation

Abstract

This work presents the sugarcane stillage treatment by membrane distillation. Stillage is the main liquid wastewater of ethanol production. This wastewater leaves the distillation column at temperatures between 70-90 ºC and, for each liter of ethanol, 12-20 liters of stillage are obtained. In this way, new treatment alternatives are necessary in order to reduce the ethanol production impact. Membrane distillation is a membrane separation process in which the vapor pressure difference is the driving force of the process. This process implies a simultaneously transfer of heat and mass. The main limitation of this technology is the energy requirement for heating the stream to be treated. In this work, experimental results were performed using a synthetic stillage solution as well as industrial stillage. Besides, a mathematical model was developed to simulate the membrane distillation process for a multicomponent solution treatment which has the stillage characteristics. The model was validated with the experimental data. An analysis of technical and economic feasibility showed that this technology is suitable to be integrated to the ethanol production plant and to be used for the stillage treatment at a cost of $ 1.1 per 𝑚3 of recovered water.