CHITOSAN AS A COAGULANT FOR RECOVERY OF PROTEINACEOUS SOLIDS FROM TOFU WASTE-WATER

Chitosan was an effective coagulant for recovery of proteinaceous solids from tofu wastewater. Turbidity was reduced 97% by treatment with 300 mg/L chitosan at pH 5.8 (the original pH of tofu wastewater). In the control test, turbidity was reduced 30% after gravity settling for 1 h. Greater reductions in turbidity occurred with Fe-2(SO4)(3) than with the other three inorganic salts tested. Combination of chitosan with Fe-2(SO4)(3) did not further reduce turbidity. The relative effectiveness of treatment was studied with chitosans dissolved in various organic acids and with chitosan solutions stored at 4 degrees C for 0, 3, 6, or 12 days. The proximate and amino acid analyses of the coagulated solids revealed 41.9% protein with all essential amino acids, 1.5% fat, and 0.9% ash.