Utilization of solid tapioca waste for bioethanol production by co-fermentation of baker's and tapai yeast

Abstract

Tapioca processing from cassava produces abundant solid wastes. If left untreated, it potentially increases greenhouse gas emissions from the decomposition of organic matter. These gas emissions are known to accelerate global climate change. Tapioca solid waste (TSW) has high starch and cellulose content, making energy recovery possible through conversion to bioethanol. This research aimed to produce bioethanol from TSW by a co-fermentation method of baker's and local tapai yeast. The research was conducted through multi-stages of enzymatic hydrolysis, followed by fermentation, then distillation. The hydrolysis produces hydrolyzate with a relatively high reducing sugar concentration. The ethanol fermentation results were optimally achieved in 48 h, namely substrate fermented by tapai yeast first for 24 h, followed by the addition of baker's yeast and fermentation time to 48 h. This proces produced the highest yield and bioethanol concentration, almost 2 times higher than fermentation using baker's or tapai yeast only. This results suggested that TSW can be used for bioethanol production by co-fermentation of baker's and tapai yeast method. TSW usage will reduce global warming, bioethanol production can be widely applied in various fields replacing fossil fuel, thus has the potential to reduce global warming and global climate change.