Abstract
In coagulation and foam separation method using protein (casein or gelatin), the effect of saline on removal of suspended matters was examined. When casein was used as collector and frother, the extremely high treatability for kaolin suspension contained NaCl (10,000mg·l-1) was observed. The turbidity removal efficiency was over 99% by using cassein. In comparison with NaCl free kaolin suspension, the optimum dosage of casein decreased in about 1/3. In contrast, the treatment remarkably lowered using gelatin with NaCl. Adsorptions of casein on suspended particles such as kaolin, Fe2O3, and graphite, were increased under NaCl coexistence, however, gelatin adsorption remarkably decreased. It was proven that the adsorption of protein on the suspended particle was the important factor that controls the treatment of this method. Coagulation and foam separation using casein showed the high applicability for not only general sewage but also high saline wastewater. In the condition of ferric coagulant 20mg-Fe·l-1, casein 2-3 mg·l-1, pH 5.6-5.7, 98-99% removal rates were obtained. Furthermore, this method was very effective for removal of suspended solids from estuarine saline water.
