The role of activated carbon in water treatment equipment

Activated carbon plays a crucial role in water treatment equipment. Its functions and precautions can be systematically summarized as follows:

I. Core Functions:

1. Adsorption of Organic Pollutants: Mechanism: It relies on its well-developed pore structure (mainly micropores and mesopores) to physically adsorb large organic molecules (such as pesticides and humic acids), or through chemical adsorption via surface functional groups. Application: Effectively removes discoloration and odor from water, improving sensory indicators of water quality.

2. Removal of Residual Chlorine and Disinfection Byproducts: Chemical Process: Activated carbon undergoes a reduction reaction with chlorine, further decomposing it into chloride ions. Simultaneously, it adsorbs byproducts such as trihalomethanes, protecting downstream treatment equipment (such as reverse osmosis membranes).

3. Removal of Some Heavy Metals: Conditions*: Ordinary activated carbon adsorbs lead, mercury, etc., through physical adsorption or ion exchange via surface functional groups (such as carboxyl groups); high concentrations or specific heavy metals require modification treatment (such as sulfide loading).

4. Improvement of Taste and Effectiveness: Removes dissolved organic matter and chlorine taste, improving the palatability of drinking water.

II. Application Forms and Precautions:

1. Granular Activated Carbon (GAC): Commonly used in fixed-bed filtration. Long-term use requires regular backwashing to prevent clogging.

2. Powdered Activated Carbon (PAC): Suitable for emergency treatment or intermittent addition. Fast adsorption rate but difficult to recover.

3. Maintenance and Regeneration: Replacement is required after adsorption capacity is depleted (usually every few months to a year). Regeneration can be achieved through high-temperature activation (600-900℃) or chemical treatment, but the cost is high.

Limitations:

4. Cannot remove: Inorganic salts, hardness ions (such as calcium and magnesium), and some low-molecular-weight polar substances (such as nitrates).

5. Microbial Risk: The porous structure may foster biofilm growth, requiring control with ultraviolet light or regular backwashing.

6. Synergistic Processes:
a. Pretreatment Role: Used before reverse osmosis or ion exchange to protect downstream equipment from chlorine or organic contamination.
b. Combined Technology: Used in conjunction with oxidants (such as ozone) to enhance degradation efficiency, or combined with microbial treatment (such as biological activated carbon).

Activated carbon is a highly efficient and multifunctional adsorbent in water treatment, but its effectiveness is affected by pore structure, pollutant properties, and operating conditions. Proper selection, regular maintenance, and combined use with other technologies can maximize its efficiency and ensure water quality safety.