Activated Carbon Filter

Activated carbon filters use the exceptional adsorptive capacity of granular activated carbon (GAC) to remove dissolved organic compounds, micropollutants, residual chlorine, colour-causing substances, taste and odour compounds, and trace contaminants that remain in water after primary and secondary treatment. Activated carbon is produced by high-temperature activation of carbonaceous materials (coal, coconut shell, wood), creating an extremely porous structure with a surface area of 800–1,500 m² per gram — providing an enormous number of adsorption sites within a relatively small bed volume.

In water and wastewater treatment, activated carbon filtration serves as a tertiary polishing stage following biological treatment and conventional filtration (pressure sand filters or multimedia filters). The carbon bed captures residual finer suspended solids, dissolved organics that biological treatment cannot degrade (recalcitrant compounds, endocrine disruptors, pharmaceutical residues), chlorination by-products, and odourous compounds such as hydrogen sulphide and volatile organics. The process is purely physical-chemical — no chemicals are added during filtration.

Activated carbon filters are constructed as pressure vessels (vertical or horizontal cylinder) containing a bed of GAC media with a defined iodine number or adsorption capacity matched to the specific contaminants in the application. Once the carbon bed is saturated, it can be regenerated thermally (by high-temperature reactivation) for large installations, or replaced with fresh carbon for smaller units. Backwashing with water periodically flushes accumulated suspended solids from the bed to maintain hydraulic capacity.