Efficient treatment of baker's yeast wastewater using aerobic membrane bioreactor

A membrane bioreactor (MBR) system based on a dead-end immersed hollow fiber membrane and filamentous fungus Aspergillus oryzae were used for treatment of baker’s yeast wastewater. The fungus was adapted to the wastewater in the bioreactor for two weeks before starting the continuous process. Average organic loading rate of 4.2 kg COD/m3.d was entered the bioreactor. MBR system was able to reduce the COD and BOD5 of the wastewater from 5000 and 1400 mg/L to 488 and 70 mg/L, respectively, over a period of 45 days, while the turbidity of the wastewater reduced from 134-282 NTU to less than 2.5 NTU in the permeate stream. Critical flux and a suitable operating flux were determined as 6.7 and 5 L/m2 h, respectively. The obtained results confirm that the MBR system was able to efficiently reduce the turbidity and suspended solid of the wastewater by 99.4% and 98.3%, respectively, resulting in a clear effluent.