Activated Carbon Regeneration Method

(1) Thermal regeneration method
The thermal regeneration method is the most widely used activated carbon regeneration method. During the regeneration process of activated carbon after treating organic wastewater, it is generally divided into three stages: drying, high-temperature carbonization, and activation based on the changes in organic matter when heated to different temperatures. During the drying stage, remove volatile components such as moisture from the activated carbon. The high-temperature carbonization stage involves the vaporization and desorption of some organic matter adsorbed on activated carbon, and the decomposition of some organic matter occurs, resulting in the desorption of small molecule substances. The remaining components remain in the pores of the activated carbon and become fixed carbon. The activation stage involves introducing gases such as CO2, CO, or water vapor to clean the micropores in the internal structure of activated carbon and restore its adsorption activity. The core of the regeneration process is the activation stage. [10]
The thermal regeneration method has high regeneration efficiency, short time, and a wide range of applications, but the carbon loss during the regeneration process is significant, up to 5% -10%. At the same time, the mechanical strength of the regenerated carbon decreases, and the adsorption efficiency also decreases. After multiple repeated regenerations, the adsorption performance is lost. [10]
(2) Biological regeneration method
The method of utilizing microbial metabolism to oxidize and degrade pollutants adsorbed on activated carbon is called biological regeneration. The pore size of activated carbon is generally only a few nanometers, and it is difficult for microorganisms to enter its pores. Usually, microbial cell enzymes can flow out of the cell. Through the adsorption of enzymes by activated carbon, enzymatic centers are formed on the surface of the carbon, decomposing pollutants, and achieving the goal of regeneration. The investment and operating costs of biological methods are relatively low, but the regeneration time is long, and water quality and temperature have a significant impact on the regeneration effect. At the same time, microorganisms have strong selectivity in treating pollutants, and generally cannot completely decompose all organic matter into CO2 and H2O. The intermediate products still remain in micropores, and the regeneration efficiency will be significantly reduced after multiple cycles. [10]
(3) Wet oxidation regeneration method
Wet oxidation regeneration method refers to a treatment method that uses oxygen or air as an oxidant under high temperature and pressure to oxidize and decompose organic matter adsorbed in the liquid phase into small molecule substances. The wet oxidation regeneration method is relatively simple in operation, has a small impact on adsorption capacity, and has a low carbon loss rate. It is usually suitable for treating highly toxic and biologically difficult to degrade organic matter. [10]
The above are all traditional regeneration methods. Generally, traditional activated carbon regeneration methods have the following common shortcomings: ① large loss of activated carbon; ② After regeneration, the adsorption capacity will significantly decrease; ③ The exhaust gas generated during regeneration can cause secondary pollution