| Foam fractionation is one of the new technologies developed at the beginning of the 20th century. It is known to have potentials for separating and concentrating surface-active substances with the medium of bubbles. Foam fractionation features simple process, high efficiency, low cost, less occupation of land area. It has been pointed out that foam fractionation will have a wide developing prospect.In this dissertation, foam fractionation method was used to treat soy protein wastewater. The influence of various operational parameters relevant was investigated. The experimental results showed that the separation effect was influenced to certain degree by the pH value, gas velocity, feed concentration, pool and foam height. Low gas velocity, high foam levels, low initial concentration, and pH around isoelectric point are the optimum conditions to obtain better separation effect. Based upon different evaluation criterion, the optimal operation conditions were chosen by orthogonal test. The enrichment ratio could reach up to 3.25 when concentration of feed was 0.54 g/L, pH was 5, ratio between foam and pool height was 4:1, gas velocity was 15.0 L/h. With removal efficiency as criterion, the optimum conditions was that concentration of feed was 0.54 g/L, pH was 5, ratio between foam and pool height was 3:1, gas velocity was 15.0 L/h, and the removal efficiency was as high as 48.5%.A mathematic model of foam fractionation was set up by combining theories with experiments. Suppose the following conditions hold: adsorption equilibrium, same size bubbles and regular dodecahedron model of real bubbles. Adsorption of soy protein molecules between gas and liquid surface and water-loss process in foam layer were simulated. Formula about enrichment ratio was deduced and it could be used to forecast the separation effect. The simulation results matched well with experimental data. The main factor causing deviations was the simplification of model and neglect of bubbles coalescence.
|
PDF Full Text Request