Source of Volatile VOC Waste Gas-In many industrial fields such as plastics, rubber processing, paint production, 

automobile painting and coating production, the production and processing of industrial products produce a large 

amount of waste gas containing volatile organic compounds. These waste gases are discharged into the atmosphere 

without treatment, and under certain conditions, they will form photochemical pollution, affect the air quality, 

the growth of animals and plants, and human health. Some toxic VOC waste gases have disabling, teratogenic, 

and carcinogenic effects, causing serious harm to the human body exposed to them for a long time. To this end, 

countries have promulgated corresponding laws to restrict the emission of such gases, and the "Comprehensive 

Emission Standards for Air Pollution" promulgated and implemented in 1997 in my country limits the emission 

limits of 33 pollutants, including volatile organic compounds such as benzene, toluene, and xylene.

There are many treatment technologies available for the treatment of volatile VOC waste gas. However, for waste 

gas with low concentration and large air volume of volatile organic waste gas, traditional processes have problems 

such as high investment and operation costs, low treatment efficiency, and secondary pollution after treatment. 

As a new type of air pollution control technology, the current waste gas biological treatment technology has 

been increasingly widely used. Compared with the traditional combustion method, catalytic oxidation method, 

absorption method and adsorption method, this technology has obvious advantages in the treatment of low-content 

VOC waste gas. The following will introduce several commonly used VOC waste gas treatment technologies:

1. Volatile VOC waste gas--adsorption method treatment

The principle of adsorption method for treating volatile VOC waste gas: The adsorption method uses certain substances 

with adsorption capacity such as activated carbon, silica gel, zeolite molecular sieve, activated alumina and other porous 

materials to adsorb harmful components to achieve the purpose of eliminating harmful pollution. Microporous and 

mesoporous materials have been widely used in the adsorption process. However, some of the most common porous 

materials (such as activated carbon, silica gel and molecular sieves) encountered in practice have some disadvantages, 

such as low adsorption capacity, flammability, and other problems related to regeneration. Therefore, people have been 

focusing on the adsorption capacity, fast reaction kinetics and high reversibility of new porous materials. The advantages 

of the adsorption method are high removal efficiency, low energy consumption, mature process, and recoverable solvent 

after desorption. The disadvantages are that the equipment is large, the process is complicated, the operating cost after

investment is high, and secondary pollution is generated. When there are colloidal particles or other impurities in the waste gas, 

the adsorbent is easily poisoned.

The adsorption effect of the adsorption method mainly depends on the properties of the adsorbent, the types of gas phase 

pollutants and the process conditions of the adsorption system (such as operating temperature, humidity and other factors). 

Therefore, the key issue of the adsorption method lies in the selection of the adsorbent. The adsorbent should have a dense 

pore structure, a large internal surface area, good adsorption performance, stable chemical properties, acid and alkali resistance,

water resistance, high temperature and high pressure resistance, not easy to break, and low air resistance. Commonly used 

adsorbents are activated carbon (granular and fibrous), activated alumina, silica gel, artificial zeolite, etc.

The integrated technology of adsorption and other purification methods has been promoted and applied in China to treat 

organic waste gas in many industries.

For example, liquid adsorption and activated carbon adsorption are used to treat high-concentration recyclable styrene waste gas; 

adsorption and catalytic combustion are used to treat acetone waste gas. The combination of adsorption and other purification 

methods not only avoids the shortcomings of the two methods, but also has the characteristics of high adsorption efficiency and 

no secondary pollution.

2. Volatile VOC waste gas - solvent absorption treatment

The principle of solvent absorption method for treating volatile VOC waste gas: The solvent absorption method uses liquid solvent 

as absorbent to absorb harmful components in the waste gas by liquid, so as to achieve the purpose of purification. The absorption 

process is based on the principle of similar dissolution of organic matter. Diesel and kerosene with high boiling point and low vapor 

pressure are often used as solvents to transfer VOC from gas phase to liquid phase, and then the absorption liquid is desorbed to 

recover VOC and regenerate the solvent. This method can not only eliminate gaseous pollutants, but also recover some useful substances. 

It can be used to treat VOC with a gas flow rate of generally 3000-15,000m3/h and a concentration of 0.05%-0.5% (volume fraction), 

and the removal rate can reach 95%-98%.

The advantage of this method is that it is relatively effective and low-cost for treating large air volume, normal temperature, 

and low-concentration organic waste gas, and it can convert pollutants into useful products. However, the solvent absorption method 

still has shortcomings. Due to the large investment in absorbent post-treatment and the large selectivity for organic components, 

secondary pollution is prone to occur. Therefore, when treating VOCs, it is necessary to select a variety of different solvents for absorption, 

which greatly increases the cost and technical complexity.