Whether Granular Activated Carbon or Powdered Activated Carbon is Suitable For Water Plant
Activated carbon is a kind of porous substance with large adsorption capacity. It is a non-polar adsorbent, which has good adsorption capacity for non-polar and weakly polar organic substances in water. Its adsorption effect is mainly derived from physical indications. Adsorption, such as van der Waals force. For physical adsorption, its selectivity is low, it can be adsorbed in multiple layers, and desorption is relatively easy, which is beneficial to the regeneration of activated carbon after adsorption saturation. During the high-temperature preparation process of activated carbon, a variety of functional groups are formed on the surface of the carbon. These functional groups have a chemical adsorption effect on ions in water, so activated carbon can also remove a variety of heavy metal ions. Its mechanism of action is through complexation and chelation, it has high selectivity, is a single-layer adsorption, and desorption is more difficult.
According to its appearance, activated carbon is divided into granular carbon and powdered carbon. Granular carbon is mostly used for advanced water treatment. The treatment method is generally granular activated carbon filter bed filtration. After a period of time, the saturated activated carbon is regenerated and reused. Powdered charcoal is mostly used for water pretreatment. For example, it is added to water during coagulation, and the organic matter in the water is adsorbed and then removed from the water together with the alum during precipitation. The powdered charcoal added is a one-time use and no longer Perform regeneration. Compared with powdered carbon, the treatment effect of granular carbon filtration is stable, the effluent quality is good, and the saturated activated carbon can be regenerated and reused, and the operating cost is lower. Therefore, water plants generally use granular activated carbon adsorption technology. The disadvantage of granular charcoal is that a single charcoal filter or filter tank is required, and the equipment investment is higher than that of powdered charcoal.
Activated carbon adsorption is the most effective and mature advanced water treatment technology to remove organic pollutants from water on the basis of conventional treatment. As early as the early 1950s, some water plants in Western Europe and the United States that used surface water as their water source began to use activated carbon to eliminate color and odor in water. Until now, most water plants in Western Europe that use surface water as their water source still use activated carbon adsorption to remove trace organic pollutants, colors, and odors in the water. For water plants that require long-term adsorption and operation, they generally use granular carbon filtration. , Powdered charcoal is mainly used for seasonal dosing. Since the late 1970s and early 1980s in my country, a few water plants have adopted granular activated carbon adsorption advanced treatment technology.
Activated carbon adsorption has a wide range of removal effects on many pollutants in water. Activated carbon can effectively remove substances that cause odor in water, such as geosmin and 2-methylisocamphanol. It has good adsorption capacity for aromatic compounds and various pesticides. It also has a good adsorption effect on many heavy metal ions, such as mercury, hexavalent chromium, cadmium, and lead. Activated carbon has a good removal effect on mutagenic substances in water. A number of studies have shown that the mutagenic activity of water tested positive for mutagenic activity becomes negative after activated carbon adsorption. The U.S. Environmental Protection Agency recommends activated carbon adsorption technology as the best practical technology to improve the treatment water quality of surface water sources.
