Optimization of Protein Removal from Soybean Whey Wastewater Using Chitosan Ultrafiltration

Abstract Proteins were removed from soybean whey wastewater using the chitosan flocculation technique, and this method was compared with lime flocculation, and transglutaminase polymerization. Compared with other flocculation methods, chitosan flocculation exhibited higher saccharide levels (p < 0.05), lower protein movement (p < 0.05) through the membrane and lower ultrafiltration membrane pollution levels and could be[0] useful for the development of industrial flocculation processes. The chitosan flocculation procedure was optimized by an L18(37) orthogonal array experimental design (OAD) with four factors at three levels. Optimum variables were a chitosan dosage of 0.8 g/L and a standing pH, time and temperature of 5.5, 60 min and 30C, respectively. Under these conditions, the experimental rate of protein removal was 61.21%, which was consistent with the predicted value (58.85%). These results showed that chitosan flocculation alleviated membrane fouling to a large extent. Practical Applications This study demonstrated the differences in the protein removal properties due to the different processes, i.e., lime flocculation, transglutaminase polymerization and chitosan flocculation technique, in the purification soybean whey wastewater. The information on chitosan combined with ultrafiltration would help in understanding their influences on soybean whey wastewater. Chitosan‐ultrafiltration process will facilitate the subsequent recovery of soybean polysaccharides and can be used as an environmentally friendly means for soy whey wastewater purification.