The effects of column dimensions, gas velocity and the properties of liquid and solid particles on the gas holdup s6 and the volumetric liquid-phase mass transfer coefficient kLain the solid-suspended bubble columnof liquid-solid batch operation were studied experimentally. The presence of suspended solid particles in the bubble column reduces values of sG and kLa, and their reduction by an addition of solid particles to the column is high in the transition regime and low in the heterogeneous flow regime. Based on these observations, empirical equations for % in transition flow and in heterogeneous flow, and an empirical equation for kLa a applicable to the above two flow regimes are proposed.

A novel process of an oxidative degradation of aqueous phenol effluent with hydrogen peroxide produced by electroreduction of oxygen dissolved in the effluentwasstudied. Effects of operational conditions such as pH, cathode potential, ferrous ion concentration and phenol concentration on the degradation rate of phenol were clarified. Phenol was successively degraded to carbon dioxide at pH 3 with higher efficiency rather than the other pH's. The CODcurrent efficiency at pH 3 was higher than that for the anodic oxidation process of phenol and was more than 60 % for complete degradation in the range of 260-2600 ppm of initial COD.

The effects of column dimensions, gas velocity and properties of the liquid and the solid particles on the gas holdup sG and the volumetric liquid-phase mass transfer coefficient kLa in a solid suspended bubble column with a draught tube and a conical bottom were studied experimentally in a liquid-solid batch operation. The presence of suspended solid particles in the column reduces the values of eG and kLa, and their reduction due to the addition of solid particles to the column increases with increasing solid concentration and terminal velocity of a single particle. Based on these observations, empirical equations for sG and kLa are proposed which are applicable to columns with diameter of 0.1-0.3 m.

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The behavior of suspended solid particles in the bubble column was experimentally studied.

The effects of surfactants and antifoam agent on the gas holdup s, the liquid-phase mass transfer coefficient kL and the volumetric liquid-phase mass transfer coefficient kLa in a bubble column were studied experimentally. An addition of surfactants such as //-alcohols to water increases s and decreases kL, and an addition of antifoam agent to water decreases e, kL and kLa. However, the degree of reduction of kL value by an addition of surfactant to water is lower for bubble swarms in a bubble column than that for a single bubble in stagnant liquid. Based on these observations, the previous model for estimating kL of a single bubble in aqueous solutions of surface-active substance is modified so as to be applicable to the estimation of kL for bubble swarms in a bubble column.

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