Bioconversion of molasses stillage to protein as an economic treatment of this effluent

摘要

In this research study fungi isolated from effluent of ethanol factories were identified. Optimal conditions for single cell protein (SCP) production and COD reduction of sugar beet stillage is specified for a species of Hansenula in continuous culture. Under these conditions 5.7 g dm super(-3) biomass was produced and 31% of COD was reduced without addition of further nutrients in beet molasses stillage. By addition of nitrogen and phosphorus sources, biomass production and COD reduction increased to 8.5 g dm super(-3) and 35.7%, respectively. The crude protein content of SCP in the absence of additives was 39.6% but this was increased to 50.6% in the presence of additives. The amount of essential amino acids measured was greater than that of the reference and are comparable with some other food proteins, such as soya bean and fish meal. The final effluent of SCP production was recycled to fermentation stage. The results represent 70% reduction of stillage volume.