beet sugar wastewater treatment in a hybrid biological reactor: operational optimization and kinetic coefficients calculation

The lab-scale treatment of strong beet sugar wastewater was carried out with a combination of a moving bed biofilm reactor (mbbr) and upflow sludge blanket filtration (usbf). the hybrid bioreactor was filled (35% of volume) with industrial packings made of polyethylene with an effective surface area of 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 chemical oxygen demand (cod) (3000-5000 mg/l) level, were assessed on the overall cod removal efficiency using response surface methodology (rsm). the optimal conditions were an hrt = 20 hr, biomass concentration = 8000 mg/l, an initial cod = 3000 mg/l, and an organic loading rate (olr) of 3.6 kg cod/m3.day under which the 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 promoted cod removal while increasing the initial cod deteriorated the removal performance.