Trihalomethanes are a class of substances with high content and wide distribution in drinking water disinfection by-products. It includes chloroform, monobromodichloromethane, dibromomonochloromethane and bromoform. Long-term exposure to drinking water containing such substances will increase the chance of human cancer. Our company, Eternity International chose Activated Carbon adsorption technology as the treatment means, and systematically studied the adsorption law of THMs in water on various types of Activated Carbon. Firstly, we established a detection method for four types of THMs in water using liquid-liquid extraction and gas chromatography-ECD. Secondly, equilibrium capacity experiments were conducted on Granular Activated Carbon and Powder Activated Carbon, and better carbon types were selected to treat the four THMs. The results showed that the adsorption performance of Coconut Shell Activated Carbon was better for THMs, followed by bamboo carbon, while the adsorption performance of coal Activated Carbon was poor.
The removal of organic matter by Coconut Shell Activated Carbon mainly relies on its huge specific surface area and well-developed pore adsorption. It is a good Water Treatment agent that can effectively remove organic matter from water and is an effective method to control the generation of trihalomethanes. In order to further verify the results obtained from equilibrium capacity experiments and evaluate the adsorption capacity utilization of Activated Carbon in actual carbon plants, dynamic miniature rapid penetration (MCRB) of THMs and THMs was performed for some carbon types. The TCM penetration experiments showed that the shell and bamboo carbon penetrated later and the adsorption capacity utilization of bamboo carbon and raw coal was higher. The TMRB penetration curves showed that the shell penetrated later, but the raw coal penetrated earlier. And the capacity utilization rate of trichloromethane for Coconut Shell Activated Carbon was 0.18 at c/c0=0.05 and up to 0.51 at c/c0=0.5. In order to give full play to the adsorption capacity of Activated Carbon for trichloromethane, it is recommended to use carbon column tandem operation mode. In order to make full use of the adsorption capacity of Activated Carbon for THMs, it is recommended to use carbon column tandem operation mode, so that in the case of high concentration of single column discharge water, the strict drinking water discharge standard can still be achieved and the cost of use will be greatly reduced. On balance, Coconut Shell Activated Carbon and bamboo carbon are the better carbon types for treating THMs in water.
In addition, the results of equilibrium capacity experiments show that the adsorption capacity of the same carbon type for chloroform, monobromodichloromethane, dibromomonochloromethane and bromomethane increases sequentially, not only in terms of mass concentration but also in terms of molar concentration. This is because the higher the boiling point of a substance, the lower its solubility in water, and the better the adsorption performance of Coconut Shell Activated Carbon for it. The Activated Carbon index system consisting of iodine value, phenol value, methyl blue value and tannic acid value can predict the adsorption performance of Activated Carbon for pollutants in water. For the four trihalomethanes, the phenol value was a good predictor of the adsorption performance of Activated Carbon. It can be seen from the above: among all material carbon types, Coconut Shell Activated Carbon has a better adsorption effect on trihalomethanes and raw coal has a poor adsorption effect.
Suzhou Eternity International Trading Co., Ltd.
May 08, 2019
