Reducing cheese-making by-product disposal through ethanol fermentation and the utilization of distillery waste for fertilizer

Abstract

Whey as cheese-making by-product has become a threat toward the sustainability of production process at small medium enterprises (SMEs) cheese producer. High organic contents lead high pollution load to the environment, because until now the producer still dispose the waste to the stream or land. Whey utilization through simple ethanol fermentation could reduce high organic content and highly implementable in SMEs level because its easiness. The research aimed to determine waste minimization through ethanol fermentation and the utilization of distillery wastes for fertilizer. Research was done experimentally with substrate variation (whey and napa cabbage) with and without 10% molases addition that fermented by indigenous yeasts consortium (Candida lambica and Prototheca zopfii) on various temperature (24-27°C and 17-21°C) for 96 hours. The ethanol contents measured by using dichromate oxidation methods. After fermentation finished substrates distilled two stages, the first stage distillery wastes were analyzed for the contents of N (Kjeldahl), P2O5 (Bray I) and Potassium (AAS). Results showed that the combination of whey and napa cabbage (1:1) with 10% molasses addition that fermented by Candida lambica and Prototheca zopfii on 17-21°C resulted in 11.06% of bioethanol contents in 72 hours fermentation. After two stages distillation, 11.2% substrates can converted into ethanol and 37.9% of water resulted from second stage distillation that can disposed to the environment. Meanwhile, 50.9% of first stage distillery wastes has 0.56% N, 0.83% P and 0.35 K which suitable with the Indonesian Agriculture Ministerial Decree No.28/2009 of minimum technical requirement for organic fertilizer. Ethanol fermentation from cheese whey with napa cabbage wastes and 10% molasses addition that fermented by Candida lambica and Prototheca zopfii consortium and the utilization of its distillery wastes for fertilizer could minimize wastes up to 62.1%.