GAC or granular activated carbon is a highly effective filter material used in water and wastewater treatment to remove organic compounds, odors and flavors as well as micropollutants such as pesticides, heavy metals and pharmaceutical residues.
Table of contents
Technical basics
Adsorption and filter effect
The effect of GAC is based on adsorption, a physical-chemical process in which organic and inorganic pollutants are bound to the microporous surface of the activated carbon. This large specific surface area, often over 1000 m²/g, allows efficient binding of pollutants, which adhere to the pores and are thus removed from the water.
Structure and use in filter systems
GAK filters usually consist of a filter container filled with a carbon bed. The water is passed through this carbon bed where pollutants adhere to the activated carbon. Backwashing systems are integrated to remove particles that could clog the pores and ensure long-term efficiency.
Service life and regeneration
The adsorption capacity of the activated carbon is limited. If it is exhausted, the activated carbon must be regenerated or replaced. Regeneration is usually carried out thermally, which dissolves and removes the pollutants again. Thermal regeneration is costly and energy-intensive, but necessary to maximize the cost-effectiveness of use.
Photo: Our GAK filters in GRP tanks for medium and small water flows(ALMA FIL AK)
Production of granular activated carbon (GAK)
The production of granular activated carbon involves several steps that are specifically aimed at creating the unique porous structure:
Selection of raw materials: Organic materials such as coal, coconut shells or wood are usually used.
Pyrolysis: The material is carbonized at high temperatures (400-800°C) in the absence of oxygen to remove volatile components and create a basic structure.
Activation: The carbonized mass is treated chemically (e.g. with phosphoric acid) or physically (with steam or CO₂ at temperatures of 800-1000°C). This step creates the dense network of micro- and mesopores that is responsible for adsorption.
Areas of application
Drinking water treatment:
- Removal of organic impurities and improvement of taste.
- Removal of micropollutants such as pharmaceutical residues and pesticides.
Industrial wastewater treatment:
- Application for the reduction of chemical pollutants, AOX and COD.
- Treatment of wastewater in the pharmaceutical, chemical and food industries.
Recycling and process water treatment:
- Use for the treatment of process water to enable it to be fed back into the production process.
Advantages and challenges
Advantages
- High adsorption capacity: Ideal for removing organic substances.
- Flexibility: Can be used for numerous water qualities and pollutants.
- Regenerability: Multiple thermal regeneration possible, which reduces operating costs.
Challenges
- Cost-intensive regeneration: Thermal regeneration requires specialized equipment and energy.
- Continuous monitoring: Regular checks are necessary to determine the replacement time and ensure optimum filtration.
GAK systems at ALMAWATECH
ALMAWATECH offers customized GAK filter solutionsthat are tailored to specific applications in water and wastewater treatment. Our service includes pilot testing and precise system design to match the adsorption capacity and efficiency of the filters to the requirements of the specific wastewater. All systems are also equipped with sophisticated control technology that allows optimum adjustment of the operating parameters.
Photo: Granulated activated carbon
Conclusion
Granular activated carbon plays a key role in industrial water and wastewater treatment as it offers highly effective adsorption capacities. Its versatility and regenerability make it an indispensable component of modern filtration and treatment systems. ALMAWATECH develops individual GAC filter solutions tailored to the specific requirements of our customers and supports them with comprehensive service and technological expertise.
For further information on our products, please feel free to contact us at any time!
