Performances of Anaerobic Membrane Bioreactors Treating Thin Stillage from Bioethanol Plants at Different Sludge Retention Times

Abstract

Ethanol production, as a renewable energy source and fuel additive, form starch based grains such as corn and wheat has increased rapidly in recent years to mitigate green-house gas emissions due to the extensive usage of fossil fuels and to regulate the instabilities in global fuel supply (Gao et al., 2011, Wilkie et al., 2000). However, bio-ethanol manufacturing is a water and energy intensive process that generates a high amount of concentrated wastewater called stillage and requires a high amount of energy input for downstream stillage management with centrifuges, evaporators and dryers. Therefore, its overall environmental benefit is still questionable. The only by-product of bio-ethanol production facilities is called dry distillers grains with solubles (DDGS) and it is produced through a series of energy intensive processes for concentrating the effluent coming from the main distillation process. DDGS, rich with proteins, carbohydrates, lipids and nutrients, has a high nutritional value and it is valorized in animal feed market to compensate the operation costs and to improve the overall feasibility of the process (Eskicioglu et al., 2011).