Wastewater Treatment With Activated Carbon
Activated carbon is an effective and eco-friendly adsorbent heavily used in water treatment. It has a well developed pore structure, a large specific surface area, high safety to use, and can be made from various kinds of substances containing carbon, such as wood, husks, coal, coconut shell, bamboo.
Activated carbon has been widely used for the treatment of municipal wastewater, dyeing wastewater, military wastewater, pesticides removal, photographic processing effluent, oil refinery wastewater, wasterwater containing phenol, mercury, chromium, cyanobacteria, carbon disulfide, etc. In some situations, activated carbon can also be used in combination with other treatment methods to achieve better results. For example, granular activated carbon is used in both inlet and outlet effluents of biological treatment plants. For inlet effluent, it is used to remove substances such as pentachlorophenol from pesticide plants that are toxic or inhibiting the biological treatment process. And for outlet effluent, activated carbon is used to remove residual chemicals after biological treatment, such as nitrated aromatics in some plants. The advantages of the activated carbon adsorption method for treating industrial wastewater include its adsorption efficiency and stability; it improving the resistance of microorganisms to organic poisons and heavy metals; it refining the operation conditions of the activated sludge method; its ability to treat wastewater with complex composition, variable concentration and water volume.
PAC and GAC in wastewater treatment
Normal powdered activated carbon (PAC) is easy to produce and has a relatively low price, but it is difficult to regenerate and generally cannot be reused. Whereas granular activated carbon (GAC) can be reused after regeneration, it has better working conditions and convenient operation and management.
Necessary measures of using activated carbon
When using activated carbon, the following measures are taken to ensure the adsorption performance of activated carbon: Pretreatment is required for the reduction of suspended solids in water; Use filters with appropriate parameters; Determine the contact time and choose a suitable filtration rate; Choose regeneration methods for saturated activated carbon.
Dyeing wastewater treatment
Dyeing wastewater treatment methods mainly include chemical methods, biochemical methods, and physical chemical methods. Activated carbon can effectively remove COD and treat the chromaticity of dyeing wastewater. It is especially suitable for some kinds of dye wastewater that are difficult to biologically degrade and has complex components, such as for decolorizing azo dye wastewater.
The temperature and pH of wastewater
The adsorption capacity of activated carbon will be influenced by the temperature and pH value of wastewater. Before the temperature reaches 30°C, the higher the water temperature, the stronger the adsorption capacity of activated carbon. If the water temperature is above 30°C, the adsorption capacity reaches the limit and may gradually decrease.
If the wastewater is acidic, the adsorption capacity of activated carbon for anionic substances is relatively weakened. Whereas if the wastewater is alkaline, the adsorption capacity of activated carbon for cationic substances is weakened.