Recovery of yam mucilage from the yam starch processing wastewater by using a novel foam fractionation column

It is difficult to separate a surface-active material from a wastewater with a high viscosity by foam fractionation. In order to solve the problem, a novel foam fractionation column with vertical sieve tray (VST) placed in the foam phase was developed for effectively recovering yam mucilage from the viscous yam starch processing wastewater. The effects of design parameters of VST on its foam drainage properties were investigated. The results showed that the suitable design parameters of VST were the number of trays in VST 5, the number of vertical sieve caps in each tray 4 and the number of sieve pores in each cap 28. Meanwhile, the suitable operating conditions were also determined. Under the conditions of pH 6.0, temperature 25 °C, volumetric air flow rate 50 mL/min and loading liquid volume 500 mL, the enrichment ratio and recovery percentage of yam mucilage were 5.70 and 91.21%, respectively, which were 3.77 and 1.55 times higher than those in the control column. The above results indicated that the novel foam fractionation column with VST in the foam phase could simultaneously improve the enrichment ratio and the recovery percentage of yam mucilage by strengthening foam drainage. This work was aimed at developing a novel foam fractionation column for effectively recovering a valuable byproduct from a viscous food processing wastewater and further facilitating the industrial application of foam fractionation in food industry.