Biooxidation of coal gasification wastewaters using fluidized‐bed bioreactors

Abstract

Process condensate wastewaters from two fixed-bed gasijiers have been treated successfully using a laboratory-scale, fixed-film, fluidized-bed bioreactor. Both dilute (1 to 2% raw wastewater) and more concentrated (50% stripped wastewater) were treated continuously for periods of one to three months. Biological activity was stable, recovery from upsets was rapid, and reaction rates were high due to the high concentration of microorganisms retained on the support particles. Removal of phenolics exceeded 99%, and removal of chemical oxygen demand was typically 75 to 85% for the 50% stripped wastewater with a hydraulic residence time in the bed of -5 to 7 h. Sludge production rates were comparable to rates in suspended growth systems.

Modeling phenol degradation in a fluidized‐bed bioreactor

“…This indicates that the mass transfer resistance is important in limiting the overall rate of reaction. In several previous models proposed for diffusion and reaction in biofilms, the liquid-solid mass transfer has been assumed to be negligible (Andrews and Chi-Tien, 1981;Park et a]., 1984;Wang and Chi-Tien, 1984;Worden and Donaldson, 1987). The results of this work would suggest that this assumption may lead to significant errors.…”

“…In several studies of fluidized-bed biofilm reactors for the degradation of phenol it has been noted that increasing the dissolved oxygen concentration results in an increase in the degradation rate (Donaldson et al, 1984;Worden and Donaldson, 1987). found that the phenol degradation rate was independent of the dissolved oxygen concentration over the range of conditions used in thcir work.…”

“…An ion exchange resin is used to determine the liquid-solid mass transfer coefficient. A mixed microbial culture attaches itself to the solid sup- Previous workers in this field Worden and Donaldson, 1987) have proposed models describing mass transfer and reaction in these types of reactors, but the range of experimental validation of these models is limited to the case when one substrate controls the reaction rate. In the present work, conditions are varied so that the limiting substrate undergoes a transition from phenol to oxygen.…”

Biodegradation of 3,4‐dichloroaniline in a fluidized bed bioreactor and a steady‐state biofilm Kinetic model

“…Much of this work has been carried out using phenol as a model toxic compound . 4,5,7,17,19,25,32 However, phenol is usually easily biodegradable:7 and so it is of interest to extend this work using a compound which is considered recalcitrant. Several mathematical models have been proposed which describe phenol degrading fluidized bed bioreactor s y~t e m s .…”

Apparent zero-order kinetics of phenol biodegradation by substrate-inhibited microbes at low substrate concentrations

“…(2). Subsequently, the relationships between the volumetric mass transfer coefficient and the superficial gas velocity and between the gas holdup and the superficial gas velocity were obtained by correlation of the experimental data.…”