Ozone is a strong oxidant with an oxidation-reduction potential of 2.07V, and its oxidation ability is second only to fluorine. It is an extremely strong oxidant that can be used to oxidize and degrade most organic compounds, including aromatic compounds, unsaturated compounds, difficult to biodegrade organic compounds, and toxic hazardous organic compounds. Ozone reacts quickly with organic matter, is convenient to use, and does not produce secondary pollution. At present, ozone technology has been extensively studied and applied in various fields such as wastewater treatment and flue gas treatment. Ozone oxidation technology is a highly valued new technology for water pollution control in recent years. In the process of wastewater treatment, the reaction between ozone and organic matter is achieved through two ways: one is to use the strong oxidation ability of ozone molecules themselves to directly oxidize organic pollutants in wastewater; Another approach is to achieve this by generating HO with stronger oxidation ability. The reaction of ozone degradation in aqueous solution to produce free radicals can be represented by equations ① to ⑤

According to equations ① to ⑤, under acidic conditions, the degradation of organic matter in the process of ozone treatment of wastewater mainly relies on the direct oxidation of ozone molecules; Under alkaline conditions, the degradation of organic matter in the process of ozone treatment of wastewater can be achieved simultaneously through the synergistic effect of ozone molecules and HO,

Enhance the treatment effect of ozone on wastewater. At present, ozone technology is commonly used for disinfection, decolorization, deodorization, removal of organic matter, and reduction of COD in wastewater. The use of ozone can improve water quality to a certain extent, reduce the impact load of subsequent biochemical units, and improve the biodegradability of wastewater, which is of great significance for formulating reasonable wastewater treatment strategies.

In recent years, due to the formation of complex intermediate products in the ozone oxidation process, the mineralization performance of pollutants has been poor, making it difficult to completely remove, which has limited its application in the field of wastewater treatment. Heterogeneous catalytic ozonation technology utilizes solid catalysts to promote ozone degradation and generate hydroxyl radicals (HO •), which can efficiently remove difficult to degrade organic compounds and has the technical characteristics of easy recovery. It has received increasing research attention and engineering applications. Ozone technology has significant advantages in achieving synergistic removal of multiple pollutants from flue gas, and has become a research hotspot in the field of comprehensive flue gas treatment both domestically and internationally in recent years.

For NOx emissions from coal-fired boiler flue gas, the volume fraction of insoluble NO in water is 90% to 95%. However, as the subscript x value of O in NOx increases, the solubility of NOx in water begins to increase, such as NO2, NO3, N2O5, etc., which are all soluble in water. Therefore, if a large amount of NO in the flue gas is oxidized, synergistic removal with SO2 can be achieved in the desulfurization tower. Under low temperature conditions, the key reactions between O3 and NO are as follows. The main factors affecting simultaneous desulfurization, denitrification, and mercury removal by ozone include ozone concentration, reaction temperature, and reaction residence time. These factors have varying degrees of influence on desulfurization, denitrification, and mercury removal. Finding the optimal reaction conditions can enable the process to improve pollutant removal efficiency while also considering economic benefits.

In recent years, with the rise of the organic waste gas treatment industry, technologies such as plasma and photocatalysis have also been widely applied. Although these technologies have different principles for waste gas treatment, due to the immaturity of most technologies and equipment, the role that truly plays a major role in waste gas treatment is the role of ozone. This article introduces a process that directly uses ozone to treat organic waste gas.

Process Introduction

The ozone catalytic method involves a multiphase mixture of ozone and catalytic fillers, followed by an oxidation-reduction reaction with exhaust gas. This process has multiple oxidation catalytic methods (liquid-phase and gas-phase oxidation catalytic reduction processes). The treatment system consists of two main units: an ozone host and an ozone oxidation catalytic treatment tank. The ozone gas generated by the ozone host is introduced into the modified water system in the ozone catalytic treatment tank and the permanent catalytic filler in the gas-phase oxidation catalytic treatment tank to synergistically undergo an oxidation-reduction reaction with the exhaust gas. The prepared O3 not only has high purity but also does not contain other impurity gases and harmful gases. It is also the safest, most economical, and convenient method for O3 production. The entire process undergoes oxidation-reduction and catalytic reactions in a specially designed sealed chamber. The entire reaction process is safe and harmless, and the final products after the reaction are odorless substances such as water and carbon dioxide. The system operation is simple, fast, and can be intelligently controlled. The ozone catalytic method has high operational flexibility, convenient operation and maintenance, low energy consumption, no consumables, and long service life. The catalytic filler is a permanent catalytic filler, with low operating costs and convenient maintenance.

01 Process flow

The treatment system consists of two main parts: an ozone catalytic decomposition tower and an ozone host. The ozone gas generated by the ozone host is introduced into the ozone catalytic decomposition tower and synergizes with the permanent catalytic packing inside the tower to completely oxidize and decompose the exhaust gas. The on-site exhaust gas treatment system is shown in the diagram. The organic waste gas first goes through a primary pre-treatment device to remove the acidic and alkaline substances in the waste gas. Under negative pressure, it enters the first stage ozone catalytic deodorization device. The waste gas, along with the oxidants and catalytic fillers in the tower, preliminarily decomposes the pollution factors and enters the second stage ozone catalytic deodorization device for treatment under the action of an induced draft fan. The pollution factors in the waste gas are further removed to achieve purification effect. The purified gas is pulled by the main induced draft fan and sent to a 15m high exhaust pipe for standard discharge.

Ozone technology has been applied in various fields such as wastewater, flue gas, and organic waste gas treatment. At present, organic waste gas treatment processes such as low-temperature plasma and photocatalysis essentially use ozone to decompose organic matter, thereby achieving the effect of treatment. This article proposes a process scheme for directly using ozone to treat organic waste gas, which has high efficiency, low investment, and no secondary pollution.