Engineering application of ozone catalytic oxidation in the treatment of monocrystalline silicon cutting fluid wastewater

Abstract

Monocrystalline silicon cutting fluid wastewater has the characteristics of high COD and poor biodegradability. For the wastewater from a certain monocrystalline silicon production enterprise, it was planned to adopt measures such as treating it through processes such as air flotation, biochemistry, and aerated biofilter within the enterprise until it met the takeover standards, and then mixing it with other wastewater to enter the sewage treatment plant for biochemical treatment. This posed a water quality impact problem on downstream sewage treatment plant and affected its stable operation. Therefore, an ozone catalytic oxidation treatment process section was added in front of the biochemical process section of the sewage treatment plant to pre treat the wastewater, in order to improve the inlet water quality of the biochemical section. Different ozone dosages were setted based on the COD of the wastewater discharged from the enterprise. After continuous operation for 15 days, the ozone consumption, effluent COD, and downstream wastewater treatment plant effluent COD were analyzed. The results showed that as the ozone dosage per unit mass of COD (ozone dosage ratio) increased, the effluent COD significantly decreased. However, excessive ozone dosage could cause high load operation and energy consumption of the ozone exhaust gas destruction device.Under experimental conditions, when the ozone dosage ratio varied between 0.98 mg/mg and 1.39 mg/mg, with an average of 1.20 mg/mg, the average COD of the ozone treated effluent was 83 mg/L, and the final COD of the downstream sewage treatment plant was 17 mg/L, achieving stable effluent compliance.

Keywords

• monocrystalline silicon cutting fluid
• ozone catalytic oxidation
• ozone dosage ratio