Appropriate fermentation process for tapioca's wastewater in Indonesia

Tapioca's wastewater containing BOD of about 3000 mg L^-1 was treated by means of yeast fermentation in anarobic batch scale reactors. Various dosages of the yeast ranging from 10 to 30% of effective reactor volume and wastewater concentrations in the range of 50 to 100% were investigated for different fermentation periods ranging from 3 days to 21 days. Without nutrients amendment to the diluted wastewater of 50% concentration, the yeast suspension dosage of 10% was resulted in the maximum absolute BOD removal of 40% during 14 days period. At the same conditions, increasing the yeast dosage of 30% was shown to increase the maximum absolute BOD removal up to 70% for non-diluted wastewater.