Activated Carbon Filter

Working Principle

Activated carbon filters utilize granular activated carbon to further remove residual chlorine, organics, and suspended particles from the effluent of mechanical filters, providing optimal conditions for subsequent reverse osmosis treatment.

Activated Carbon Filters primarily utilize high-carbon, high-molecular-weight, and large-specific-surface-area activated carbon organic flocs for physical adsorption of impurities in water to meet water quality standards. As water flows through the pores of the activated carbon, various suspended particles and organic matter are adsorbed within the pores due to van der Waals forces. Additionally, chlorine (hypochlorous acid) adsorbed on the activated carbon surface undergoes a chemical reaction on the carbon surface, being reduced to chloride ions, effectively removing chlorine and ensuring the residual chlorine in the outlet water is less than 0.1 ppm, satisfying the operating conditions of the RO membrane. Over time, the retained substances within and between the pores of the activated carbon gradually increase, causing the pressure difference before and after the filter to rise until it fails. Typically, by measuring the pressure difference before and after the filter, backwashing the filter medium with reverse water flow is used to strip most of the retained substances adsorbed in the activated carbon pores and carry them away with the water flow, restoring the adsorption function. When the activated carbon reaches its saturated adsorption capacity and completely fails, it should be regenerated or replaced to meet engineering requirements.

When an activated carbon filter is impaired due to trapping excessive mechanical impurities affecting its normal operation, backwashing can be used for cleaning. By using reverse water flow, the sand filter layer inside the filter can be loosened, allowing the trapped matter adhering to the filter material surface to be stripped and carried away by the backwashing water. This is beneficial for removing sediments and suspended particles from the filter layer, preventing the filter material from clogging, and restoring its ability to filter out pollutants and chlorine, thereby achieving the cleaning objective. The backwashing cycle is controlled by setting the pressure difference between the inlet and outlet, typically every three to four days, with the specific interval depending on the original water turbidity.

Structural Features

The equipment body is a cylindrical steel structure with upper and lower elliptical heads. The filter material is Q235-A or 304 stainless steel, lined with sulfurized rubber for corrosion resistance. Inside, a distributor is installed at the inlet, and a water collection device is located at the bottom, filled with 1200mm of activated carbon and 200mm of quartz sand.

The activated carbon filters are filled with fruit shell activated carbon, which boasts the advantages of light density, high porosity, strong wear resistance, and large adsorption capacity.