Abstract
The aim of this work was to investigate the aerobic degradation of high-strength industrial (refinery) wastewaters in the inverse fluidized bed biological reactor, in which polypropylene particles of density 910 kg/m3 were fluidized by an upward flow of gas through a bed. Measurements of chemical oxygen demand (COD) versus residence time t were performed for various ratios of settled bed volume to reactor volume (Vb/VR) and air velocities u. The largest COD reduction, namely, from 54,840 to 2,190 mg/l, i.e. a 96% COD decrease, was achieved when the reactor was operated at the ratio (Vb/VR) = 0.55, air velocity u = 0.046 m/s and t = 65 h. Thus, these values of (Vb/VR), u and t can be considered as the optimal operating parameters for a reactor when used in treatment of high-strength refinery wastewaters. In the treatment operation conducted in a reactor optimally controlled at (Vb/VR) = 0.55, u = 0.046 m/s and t = 65 h, the conversions obtained for all phenolic constituents of the wastewater were larger than 95%. The conversions of about 90% were attained for other hydrocarbons.
Highlights
The application of a fluidized bed technology to biological wastewater treatment has brought a remarkable breaktrough
The aim of this work was to investigate the aerobic degradation of high-strength industrial wastewaters in the inverse fluidized bed biological reactor, in which polypropylene particles of density 910 kg/m3 were fluidized by an upward flow of gas through a bed
The largest chemical oxygen demand (COD) reduction, namely, from 54,840 to 2190 mg/l, i.e. a 96% COD decrease, was achieved when the reactor was operated at the ratio (Vb/VR) = 0.55, air velocity u = 0.046 m/s and t = 65 h
Summary
The application of a fluidized bed technology to biological wastewater treatment has brought a remarkable breaktrough. The technology owes its high-rate success to much higher surface area and biomass concentration than those that can be achieved in the conventional treatment processes. A fluidized bed biological reactor (FBBR) has attracted considerable interest as an alternative to the conventional suspended growth and fixed-film wastewater treatment processes due to its high efficiency performance. Treatment of industrial wastewaters requires a great deal of space when using systems based on activated sludge in which the retention time is many days [1]. A three-phase (gas-liquid-solid) FBBR has been successfully applied in aerobic biological treatment of industrial and municipal wastewaters [5,6,7,8]. The superior performance of the FBBR stems from the very high biomass concentration (up to 30 - 40 kg/m3) that can be achieved due to immobilisation of cells onto or into the solid particles
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