Hollow Fiber Membrane Bioreactor for COD Biodegradation of Tapioca Wastewater

The present work studied the application of membrane bioreactor (MBR) for tapioca wastewater processing that contained chemical oxygen demand (COD) ranging from 4000-9000 mg/L. A preliminary study was initially conducted in order to evaluate membrane performance with respect to its flux with MLSS concentration ranging from 4,500 to 10,500 mg/L. It was clear that fouling was observed during the initial period of study for the whole range of MLSS concentration resulting in drastic flux decline. Increasing trans-membrane suction pressure only yielded slight flux enhancement in 4,500 MLSS concentration. The contrast result was found for both 8,500 and 10,500 MLSS concentration. However, their flux performance could be increased by applying aeration to the system. In batch operation mode using tapioca wastewater, a slight decrease in COD removal was observed when lower hydraulic retention time (HRT) was applied. Lower HRT also suffered relatively sharper flux decline. However, COD removal was only slightly affected by HRT. In a continuous operation mode, it was observed that above 94% COD removal could be attained using HRT in about 24 hours. However, MBR suffered severe membrane fouling in the 4th day of operation resulting in a drastic flux drop below 1 lmh. The chemical cleaning mechanism employed in MBR was found to give the most prominent result since around 67% of flux recovery could be achieved.