Document Type : Research Paper
University of Isfahan
Chemical & Petrolium Engineering Department, Sharif University of Technology, Tehran, Iran
The lab-scale treatment of strong beet sugar wastewater was carried out in the combination of a moving bed biofilm reactor (MBBR) and an up flow sludge blanket filtration (USBF). The hybrid bioreactor was filled (35% of volume) with industrial packings made of polyethylene with an effective surface area 480 m2/m3 to provide the necessary surface for biofilm growth. The effect of various operating conditions including hydraulic retention time (HRT = 12-20 hr), biomass concentration (6000– 8000 mg/L), and initial COD (3000-5000 mg/L) level were assessed on the overall COD removal efficiency using the response surface methodology (RSM). The optimal conditions were found to be HRT = 20 hr, biomass concentration = 8000 mg/L, initial COD = 3000 mg/L and organic loading rate (OLR) 3.6 kg COD/m3.day, under which COD removal efficiency was 98%. The modified Stover–Kincannon model was applied to predict the biokinetic coefficients for COD removal; the saturation constant (KB ) and the maximum total substrate utilization rate (Umax) were in the range 58-101.6 and 57.5- 97 as g/L.day, respectively. The results revealed that raising HRT or biomass concentration would promote COD removal while increasing the initial COD deteriorates the removal performance.