3.3.4 Granular Activated Carbon
Activated carbon used in water purification is produced from different materials such
as coconut shells, wood, and coal. Particularly, it has high potential in water
treatment due to its characteristics such as porous texture, high surface area functional groups, etc. Granular activated carbon (GAC) is used in both filtration and
post-filtration methods to capture organic and odor compound. Generally, GAC is
replacing RSF in most of the places, thereby reducing the necessity of further
filtration. The filters that are based on GAC can operate at a high flow rate than
SSF. Therefore, it is predominantly used in water treatment plants where the space is
limited. Furthermore, the life cycle of GAC depends on how long the bed gets
saturated with the targeted pollutants. As far as the biological activity is concerned, it
can generate issues like clogging, dead zones, and detachment of microbes from the
surface of GAC.
Nowadays, silver impregnation is being done to the surface of carbon to remove
chemicals and inactivate microbes. Further, activated carbon in combination with a
chemical disinfectant is also employed to remove both chemical and biological
contaminants. To obtain maximum efficiency, it is desirable to have a maximum
specific surface area in the smallest volume. Generally, GAC exhibits a specific
surface area ranging from 300 to 1500 m
2 /g and an abundant quantity of polar
functional groups. As a result of functional groups, microbes are trapped on the
carbon surface. It is reported that GAC removes microbes (E.coli, MS2, and spores
of Cryptosporidium parvum and Giardia lamblia) by the process of adsorption. The
centralized system involves various treatment stages such as sedimentation, coagulation/flocculation, filtration, and disinfection. On the other hand, the decentralized
system consists of MF/UF and GAC filters.
4 Future Perspectives on Water Disinfection
The quest for safe water has been the main priority across the globe. The necessity
increases for humans due to population growth, natural resources depletion, and
ill-managed treatment methods for water, especially the lack of disinfection and
treatment methods, specifically in small villages. We need to create awareness about
the existing systems and motivate people to have clean and safe drinking water. This
chapter describes a variety of disinfection techniques for safe water, such as chemical and physical methods, including traditional systems such as chlorination and
sand filtration. Each technique has merits and demerits for having safe water.
Therefore, the hybrid process can be accepted as a solution to have safe water.
The factors that decide the economics of the process are the physical, chemical, and
biological quality of water and environmental factors like pH, temperature, etc.
6 Strategies and Limitations of Water Treatment Methods for Point-of-Use. . .
131
Activated carbon used in water purification is produced from different materials such
as coconut shells, wood, and coal. Particularly, it has high potential in water
treatment due to its characteristics such as porous texture, high surface area functional groups, etc. Granular activated carbon (GAC) is used in both filtration and
post-filtration methods to capture organic and odor compound. Generally, GAC is
replacing RSF in most of the places, thereby reducing the necessity of further
filtration. The filters that are based on GAC can operate at a high flow rate than
SSF. Therefore, it is predominantly used in water treatment plants where the space is
limited. Furthermore, the life cycle of GAC depends on how long the bed gets
saturated with the targeted pollutants. As far as the biological activity is concerned, it
can generate issues like clogging, dead zones, and detachment of microbes from the
surface of GAC.
Nowadays, silver impregnation is being done to the surface of carbon to remove
chemicals and inactivate microbes. Further, activated carbon in combination with a
chemical disinfectant is also employed to remove both chemical and biological
contaminants. To obtain maximum efficiency, it is desirable to have a maximum
specific surface area in the smallest volume. Generally, GAC exhibits a specific
surface area ranging from 300 to 1500 m
2 /g and an abundant quantity of polar
functional groups. As a result of functional groups, microbes are trapped on the
carbon surface. It is reported that GAC removes microbes (E.coli, MS2, and spores
of Cryptosporidium parvum and Giardia lamblia) by the process of adsorption. The
centralized system involves various treatment stages such as sedimentation, coagulation/flocculation, filtration, and disinfection. On the other hand, the decentralized
system consists of MF/UF and GAC filters.
4 Future Perspectives on Water Disinfection
The quest for safe water has been the main priority across the globe. The necessity
increases for humans due to population growth, natural resources depletion, and
ill-managed treatment methods for water, especially the lack of disinfection and
treatment methods, specifically in small villages. We need to create awareness about
the existing systems and motivate people to have clean and safe drinking water. This
chapter describes a variety of disinfection techniques for safe water, such as chemical and physical methods, including traditional systems such as chlorination and
sand filtration. Each technique has merits and demerits for having safe water.
Therefore, the hybrid process can be accepted as a solution to have safe water.
The factors that decide the economics of the process are the physical, chemical, and
biological quality of water and environmental factors like pH, temperature, etc.
6 Strategies and Limitations of Water Treatment Methods for Point-of-Use. . .
131