When selecting activated carbon for wastewater treatment, it is necessary to comprehensively consider the characteristics of the wastewater (such as pollutant type, concentration, pH value, etc.) and process requirements (such as adsorption efficiency, cost, etc.).

1. Powdered activated carbon (PAC)

Features: Small particle size (10–50 microns), large specific surface area (800–1,500 m²/g), and fast adsorption rate.

Applications:

Emergency treatment or intermittent wastewater (such as sudden pollution incidents).

Removes color, odor, and certain organic pollutants (e.g., phenols, benzene compounds).

Used in conjunction with coagulation-sedimentation processes (added to reaction tanks).

Advantages: Flexible dosing, no fixed equipment required.

Disadvantages: Difficult to recover, single-use, higher operating costs.

2. Granular Activated Carbon (GAC)

Features: Larger particle size (0.5–4 mm), high mechanical strength, and reusable.

Applications:

Continuous flow wastewater treatment (e.g., fixed-bed adsorption towers, filters).

Advanced treatment of COD and trace toxic substances (e.g., pesticides, heavy metals) in secondary effluent.

Biological activated carbon (BAC) process: Combines microbial degradation with adsorption.

Advantages: Can be reused (thermal or chemical regeneration), resulting in lower long-term costs.

Disadvantages: High initial investment, requires配套regeneration equipment.

3. Columnar activated carbon

Features: Cylindrical particles, high mechanical strength, resistant to powdering.

Applications:

High-flow wastewater treatment (e.g., industrial wastewater filtration towers).

Liquid-phase applications after gas-phase adsorption (e.g., wastewater treatment after oil and gas recovery).

4. Activated carbon fiber (ACF)

Features: Fibrous structure, extremely large specific surface area (1000–2000 m²/g), extremely fast adsorption rate.

Applications:

High-concentration, difficult-to-degrade organic compounds (e.g., dye wastewater, pharmaceutical wastewater).

Precision treatment (e.g., adsorption of trace heavy metals).

Disadvantages: High cost, primarily used in small-scale or specialized applications.

5. Special modified activated carbon

Chemical modification:

Sulfur-loaded activated carbon: Removes heavy metals such as mercury.

Oxidized modified activated carbon: Enhances adsorption of polar organic compounds (e.g., phenol).

Alkaline activated carbon: Treats acidic wastewater or adsorbs acidic gases (e.g., H₂S).

Biological modification: Loaded with microorganisms to synergistically degrade organic compounds (e.g., BAC process).