There are various treatment methods for VOC (Volatile Organic Compounds) waste gas generated from paint coating lines. The following are some common treatment approaches:

Adsorption Method
Principle: Utilize the porous structure and large specific surface area of adsorbents (such as activated carbon, zeolite, etc.) to adsorb the pollutants in VOC waste gas onto the surface of the adsorbents, thus achieving the purpose of purifying the waste gas.
Advantages: It has a high adsorption efficiency and can effectively remove low-concentration VOC waste gas; the equipment is simple and easy to operate; valuable organic substances can be recovered.
Disadvantages: The adsorption capacity of adsorbents is limited, and it is necessary to replace or regenerate the adsorbents regularly; the regeneration process may cause secondary pollution.

Combustion Method
Direct Combustion Method
Principle: Introduce the VOC waste gas directly into the combustion furnace and completely burn and decompose it into harmless substances such as carbon dioxide and water at high temperatures (generally 800 - 1200 °C).
Advantages: The treatment efficiency is high, reaching over 99%; it is suitable for treating high-concentration, small-air-volume VOC waste gas.
Disadvantages: It consumes a large amount of fuel and has high operating costs; there are certain requirements for the concentration of combustible components in the waste gas, and auxiliary fuel needs to be supplemented if the concentration is too low.

Catalytic Combustion Method
Principle: Under the action of a catalyst, reduce the combustion temperature of the VOC waste gas, enabling organic substances to undergo oxidation reactions at relatively low temperatures (generally 200 - 400 °C) and generate carbon dioxide and water.
Advantages: Compared with the direct combustion method, the catalytic combustion method has the advantages of low combustion temperature, low energy consumption, and low operating costs; it has relatively lower requirements for the concentration of organic substances in the waste gas.
Disadvantages: The catalyst is expensive and is prone to poisoning and deactivation, so it needs to be replaced regularly; there are certain requirements for the impurity content in the waste gas, and pretreatment is required.

Condensation Method
Principle: By reducing the temperature or increasing the pressure, make the organic substances in the VOC waste gas reach a saturated state, so that they condense into a liquid and are separated from the waste gas, thus realizing the purification of the waste gas.
Advantages: It is suitable for treating high-concentration, high-boiling-point VOC waste gas, and the recovered organic substances have a relatively high purity and can be directly reused.
Disadvantages: It has a poor treatment effect on low-concentration, low-boiling-point VOC waste gas; the equipment investment and operating costs are relatively high, and a large amount of cooling capacity is consumed.

Biological Method
Principle: Utilize the metabolic functions of microorganisms to decompose the organic substances in the VOC waste gas into carbon dioxide, water, and microbial cell substances. During the growth process, microorganisms use organic substances as carbon sources and energy sources and convert them into harmless substances through a series of biochemical reactions.
Advantages: The treatment cost is low, and the operating expenses are small; there is no secondary pollution, and it is environmentally friendly; it is suitable for treating low-concentration, large-flow-rate VOC waste gas.
Disadvantages: The treatment efficiency is relatively low, and it occupies a large area; there are certain requirements for the composition and concentration of the waste gas, and the growth of microorganisms requires suitable environmental conditions, such as temperature, humidity, and pH value.

Plasma Method
Principle: Generate plasma through methods such as high-voltage discharge. The plasma contains a large number of active particles such as high-energy electrons, ions, and free radicals. These active particles collide, excite, and ionize with the organic molecules in the VOC waste gas, decomposing the organic substances into small molecular substances or carbon dioxide and water.
Advantages: The treatment efficiency is high, and it can quickly and effectively decompose the organic substances in the VOC waste gas; the equipment is compact and occupies a small area; it has a strong adaptability to the concentration and flow rate of the waste gas.
Disadvantages: The energy consumption is relatively high, and the operating cost is relatively high; it may produce by-products such as ozone, and subsequent treatment is required.

In practical applications, usually, one or more combined treatment methods will be selected according to the specific composition, concentration, flow rate, and treatment requirements of the VOC waste gas generated from the paint coating line to achieve the best treatment effect and economic benefits.