BUBBLE-COLUMN REACTORS FOR WASTE-WATER TREATMENT .1. THEORY AND MODELING OF CONTINUOUS COUNTERCURRENT SOLVENT SUBLATION

Solvent sublation is a nonfoaming wastewater treatment process that co mbines the benefits of bubble fractionation and liquid-liquid extracti on in a way that does not require mixers, settlers, or subsequent down stream treatment. A review of past work on small lab-scale batch colum ns revealed that removal efficiencies of nonvolatile and volatile orga nic compounds are generally higher than those observed in bubble fract ionation, air stripping, and conventional liquid-liquid extraction. In this work, the first of a three-part series, the transport mechanisms in a three-phase continuous, countercurrent sublation process are pre sented. Two mathematical models, namely, the series CSTR model (SCM) a nd the two-phase axial dispersion model (ADM2), are developed. It is s hown that these two models are equivalent and can be used interchangea bly with the aid of a simple expression. Nondimensional correlations, based upon simulated data obtained from the SCM, are generated to pred ict the steady-state fractional removal, FR, and the separation factor , Sigma (ratio of effluent solvent concentration to effluent water con centration), for strongly hydrophobic compounds, The effects of operat ional, hydrodynamic, thermodynamic, and design variables on sublation performance are discussed.