The implementation process of ozone oxidation in wastewater treatment
Pre-treatment: The wastewater first undergoes conventional treatments such as grating, sedimentation tank, and primary sedimentation tank to remove large suspended particles and sand grains, in order to protect the expensive ozone equipment. Usually, biochemical treatment (such as activated sludge process) is also included as the main process.
Ozone addition: The pre-treated wastewater is pumped into the contact reaction tank. At the same time, the ozone-oxygen mixed gas produced by the ozone generator is injected into the wastewater through a carefully designed gas distributor.
Mass transfer and reaction: In the reaction tank, the ozone gas forms tiny bubbles and fully contacts and dissolves with the wastewater during the upward movement. The dissolved ozone immediately undergoes a series of complex chemical reactions with the pollutants in the water. The hydraulic retention time and ozone dosage in this stage are key operating parameters.
Solid-liquid separation: The wastewater after the reaction flows out of the contact tank and enters the subsequent solid-liquid separation unit, which is usually a secondary sedimentation tank or a more common sand filter/activated carbon filter. This is because ozone oxidation may convert some large molecular organic substances into biodegradable small molecules, or produce a small amount of flocs, which need to be removed from the water through sedimentation or filtration to obtain clear effluent.
Tail gas treatment: The tail gas collected from the top of the contact tank is sent to the tail gas destruction device (ozone destruct unit containing ozone decomposition catalyst) to ensure that the ozone concentration in the discharged gas is below the safety standard.
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