The use of activated carbon in the field of water treatment has grown significantly due to its high efficiency and versatility. It is widely used to purify water to get rid of pollutants, impurities, and undesired elements. Because to its effectiveness, efficiency, and affordability, activated carbon has become more widely used in the treatment of water. The function of activated carbon for water treatment, its advantages, and how it can support efforts to provide communities with safe and clean drinking water are all covered in this article.
Benefits of Activated Carbon in Water Treatment
Activated carbon has become more widely used as a water treatment technique because it can remove a wide range of contaminants and impurities from water. Due to its porous nature, which provides a significant surface area for adsorption, chlorine, insecticides, and volatile organic pollutants can all be efficiently removed (VOCs). There are several techniques to treat water with activated carbon, some of which are given below:
Impurities Removal: Chlorine, a key component in water treatment processes, may be removed from water very effectively using activated carbon. Water with activated carbon has a superior flavor because it doesn’t have a chlorine-related taste and odor. Moreover, activated carbon can remove VOCs, which are present in many home objects and can be dangerous if swallowed.
Enhancement of Taste and Odor: Water can become more palatable by having disagreeable tastes and odors removed by the use of activated carbon. This is crucial in locations where the water supply has an unpleasant taste or odor because of naturally occurring minerals or because of industrial contamination.
Reduction of Hazardous Substances: Lead, mercury, and asbestos are just a few of the toxic compounds that activated carbon may successfully remove from water. Activated carbon is a reliable method for eliminating these contaminants from water because they can have detrimental effects on one’s health if consumed.
Types of Activated Carbon Used in Water Treatment
There are three main types of activated carbon used in water treatment: powdered activated carbon (PAC), granular activated carbon (GAC), and extruded activated carbon (EAC). Each type has unique properties, advantages, and limitations that make them suitable for different water treatment applications.
Powdered Activated Carbon (PAC): PAC is a fine powder that is commonly used in water treatment applications due to its high surface area and rapid adsorption properties. It is made from crushed or ground carbon sources, such as coconut shells or coal, that are then activated through a high-temperature process. PAC is typically used in small-scale applications, such as in point-of-use water filters or in batch treatment systems.
Some advantages of PAC include high adsorption capacity, fast adsorption rate, and low cost.
However, PAC can be difficult to handle and can cause clogging in filtration systems due to its fine particle size.
Granular Activated Carbon (GAC): GAC is utilized in larger-scale water treatment systems and is bigger in size than PAC. It is made from bigger carbon sources that are subsequently heated to a high temperature, like wood or coconut shells. Water passes over a bed of GAC in filtration systems where GAC is frequently utilized.
GAC has a number of benefits, including a smaller pressure drop, a longer lifespan, and a greater ability to remove certain impurities, such as dissolved organic compounds.
GAC, however, can cost more than PAC and take up more room when installed.
Extruded Activated Carbon (EAC): Activated carbon that has been extruded into a cylindrical shape is known as extruded activated carbon (EAC). EAC is frequently employed in water treatment applications, such as in industrial settings, where large flow rates and pressure drops are encountered.
High mechanical strength, resistance to abrasion, and effectiveness in eliminating trace impurities like arsenic and selenium are a few benefits of EAC.
EAC can, however, be more expensive and have a lesser adsorption capacity than other kinds of activated carbon.
Activated Carbon Adsorption Mechanisms
Contaminants are drawn physically and chemically to the surface of activated carbon as part of the adsorption process. The enormous surface area of activated carbon offers a lot of pollutant adsorption sites. As pollutants come into contact with the surface of the activated carbon and stick to it, adsorption takes place. Impurities including chlorine, pesticides, and volatile organic compounds (VOCs) can be effectively removed from water with this method.
The surface area, the distribution of pore sizes, and the pH all have an impact on the adsorption process. More adsorption sites are available to remove pollutants from water when activated carbon’s surface area increases. The amount of pollutants that can be adsorbed depends on the pore size distribution, which is equally important. Bigger molecules can fit through larger pores, but smaller pores are better at eliminating smaller molecules.
Factors Affecting the Performance of Activated Carbon
A number of factors can affect the effectiveness of activated carbon when it comes to water treatment, including the concentration of contaminants in the water. It is important to determine the optimal concentration of activated carbon for a given concentration of contaminants as if the concentration is too high, the activated carbon may become saturated quickly, reducing its effectiveness.
Contact time: The contact time between the water and the activated carbon is an essential element in determining the success of the treatment. Allowing sufficient contact time allows more contaminants to be adsorbed, thus rendering the process more efficient. Conversely, if this period is too limited, the activated carbon may not be able to eliminate all pollutants, which leads to poorer water purity.
Water temperature: The temperature should also be taken into account when formulating a water treatment system that utilizes activated carbon. Higher temperatures raise reaction rates, resulting in a restrained ability for adsorption by the activated carbon.
pH value: The pH of the water can also affect the performance of activated carbon. As previously stated, the surface charge of activated carbon changes with pH, affecting its ability to adsorb contaminants. As a result, when designing an activated carbon water treatment system, it is critical to take the pH of the water into account.
Sence of other substances: Finally, the presence of other substances in the water, such as dissolved solids, can have an effect on the performance of activated carbon. These substances can compete with contaminants for adsorption sites on the activated carbon surface, reducing their effectiveness. When designing an activated carbon water treatment system, it is critical to consider the quality of the water being treated.
Applications of Activated Carbon in Water Treatment
Because of its exceptional adsorption capabilities, activated carbon is widely used in a variety of water treatment applications. Industrial water treatment, groundwater treatment, and point-of-use (POU) water treatment systems are some of the most common applications of activated carbon in water treatment.
Industrial water treatment: Many industries generate wastewater with high levels of contaminants like heavy metals and organic compounds. To remove these contaminants and lessen the environmental impact of industrial activities, activated carbon can be used to treat wastewater.
Groundwater treatment: Groundwater treatment is another common use for activated carbon. Agricultural chemicals, pesticides, and volatile organic compounds, among other contaminants, can contaminate groundwater (VOCs). Activated carbon is frequently used to treat groundwater in order to remove contaminants and ensure that it meets regulatory drinking water standards.
Point-of-use (POU) water treatment systems: Aside from the applications listed above, activated carbon is commonly used in point-of-use (POU) water treatment systems. These systems are typically used in residential or commercial settings to treat water at the point of consumption. In these systems, activated carbon filters are commonly used to remove impurities such as chlorine, taste and odor compounds, and volatile organic compounds (VOCs).
Maintenance and Regeneration of Activated Carbon
Activated carbon is a powerful adsorbent that is commonly used in water treatment processes. To maintain its effectiveness, it is important to properly maintain and regenerate the activated carbon. The following are some important points to keep in mind for maintaining and regenerating activated carbon:
Over time, activated carbon can become saturated with contaminants, reducing its effectiveness. Regular maintenance and regeneration can help to restore the activated carbon’s adsorption capacity and extend its useful life.
Thermal regeneration and chemical regeneration are the two main methods for regenerating activated carbon. Thermal regeneration is the process of heating activated carbon to a high temperature in order to burn off contaminants. The activated carbon is soaked in a chemical solution to remove contaminants during chemical regeneration.
The frequency of maintenance and regeneration will be determined by a number of factors, including the level of contaminants in the water, the type of activated carbon used, and the water flow rate. Maintenance and regeneration should be performed at least once a year as a general rule.
Maintenance and regeneration methods will differ depending on the application and type of activated carbon used. For example, in some cases, the activated carbon in the filter may need to be removed and replaced with fresh activated carbon. In other cases, in-place regeneration may be possible.
Environmental Impact of Activated Carbon in Water Treatment
The advantages of using activated carbon in water treatment include its ability to remove a wide range of contaminants such as pesticides, chlorine, and volatile organic compounds (VOCs), as well as improve taste and odor. However, the production and disposal of activated carbon can have an impact on the environment.
One disadvantage of using activated carbon in water treatment is the high energy consumption and greenhouse gas emissions during the manufacturing process. Furthermore, the disposal of spent activated carbon can cause contaminants to be released into the environment.
Compared to other water treatment methods, activated carbon generally has a lower environmental impact than chemical treatment methods, such as chlorination or ozonation. However, it may have a higher environmental impact than physical treatment methods, such as filtration or sedimentation.
