The Technology On Recovering The Protein From Potato Processing Wastewater By Foam Fractionation

During the process of starch production, a large amount of protein wastewater is generated, leading to COD as high as20000mg/L. If it is discharged without any treatments, the environment will be subject to serious pollution and result in abundant loss of the potato protein. In this paper, potato processing wastewater was separated for recovering potato protein using two-stage foam separation.In order to improve enrichment ratio, the adsorption and drainage of potato protein in liquid phase and foam phase were studied. The results show the effects of operating conditions (temperature, pH and so on) on the adsorption and drainage were different. For example, when temperature was low, the adsorption of potato protein was good. However, the drainage was bad. Meanwhile, the liquid hold up of spiral column was higher than the liquid hold up of straight column. So the spiral internal component improved the drainage in foam phase.A two-stage foam separation technology was designed to improve both the enrichment ratio and recovery percentage of potato protein. A best enrichment ratio of potato protein of4.69was obtained under the optimal conditions of temperature45℃, pH7, volumetric airflow rate100mL/min and liquid loading volume300mL. Based on a higher enrichment ratio of potato protein, the volumetric airflow rate of the second-stage foam separation was determined. The total enrichment ratio and recovery percentage of potato protein are4.69and85.3%by using the two-stage foam separation technology.It found that the effects of operating conditions on foam separation of potato protein and soybean protein had a similar tendency by comparison. So the effects of operating conditions (temperature, pH and volumetric airflow rate) on foam separation of protein were discussed. Meanwhile, the effects of enhanced foam drainage using the type of foam separation column and internal component were analyzed. The results show the effects of temperature and volumetric airflow rate on foam separation of potato protein and soybean protein had the same tendency. When the surface tension was the minimum, the enrichment ratio was the best. Foam separation column of inclined foam phase or the column with the spiral internal component could enhance foam drainage. On the other hand, the effects of temperature on viscosity of potato processing wastewater were more than soybean protein wastewater. The foamability of potato protein was worse and the stability was better with temperature increasing. Meanwhile, the column with the spiral internal component could be better to separate from a high concentration and a high viscosity system.