Grain Sorghum Stillage Processing: Nutrient Recovery and Pollution Control
ABSTRACT STILLAGE from fuel alcohol plants contains reusable nutrients and water polutants. Grain sorghum stillage from a farm-scale fuel alcohol plant was separated into wet solids and liquid fractions by various processes. Dry matter recovery averaged 42% with a screw press, 21 and 34% with two centrifuges, 98% with a reverse osmosis unit, and 19% with ultrafiltration. More than 99% of the nitrogen (protein) was recovered with three stages of treatment. Resulting wastewater still had a chemical oxygen demand of 4100-9400 ppm and would require biological treatment or land application.