Process Research on Advanced Treatment of Yeast Wastewater Through Enhanced Catalytic Ozonation

After the secondary treatment of yeast wastewater, the chemical oxygen demand(COD) usually remains very high (approximately 800-1500mg/L) in this effluent, which contains various degradation-resistant substances. Because of the presence of bicarbonate ions, which are the inhibitor of center dot OH free radical chain reaction, the direct ozonation of a secondary effluent treatment is limited. In this study, the addition of calcium hydroxide as a pretreatment not only eliminates adverse effects of bicarbonate ions on chain reaction of hydroxyl free radical's generation, but also enhances the indirect ozonation by increasing the pH value up to 11. At the same time, heterogeneous catalytic ozonation treatment is also conducted on the secondary effluent of yeast wastewater by the use of manganese sand (containing manganese dioxide as an effective constituent). The COD of the raw water is reduced to 389 mg/L from 853 mg/L, and the total removal rate reaches 54%. Process analysis is conducted on the pH value, Oxidation-Reduction Potential (ORP) value, and the concentration of dissolved ozone through an online monitoring system. A control method is also proposed to strengthen the catalytic ozonation technology by combining the ozone consumption and COD removal variation.