Activated carbon: how it effectively purifies water

How activated carbon works and its role in wastewater treatment systems

Businesses—and even residential properties—that produce waste in the form of wastewater or sludge require efficient purification systems to ensure the highest level of water treatment. In this context, activated carbon is becoming an increasingly popular solution for water treatment thanks to its high absorption capacity and long-lasting performance.

Traditional biological reactors used for industrial wastewater treatment are becoming less effective and less common. This is mainly due to the demand for higher purification performance and increasingly strict environmental regulations, such as Legislative Decree No. 152/2006, which sets stringent limits on the quality of treated wastewater.

Powdered activated carbon (PAC) is used because, when integrated into a biological system, it can boost the existing purification capacity without major modifications to the facility’s infrastructure.

What is activated carbon?

Activated carbon is a porous material made of amorphous carbon, characterized by an extremely high surface area. This allows it to adsorb numerous substances such as pollutants, solvents, dyes, hydrocarbons, and chlorine. Because of this, it is widely used in filtration, purification, and treatment processes for both liquids and gases.

Its high carbon content forms a three-dimensional sponge-like structure made up of tiny graphite crystals. Adsorption takes place through this microporous network, which traps unwanted molecules and improves the quality of water, air, and other fluids.

There are two main types of activated carbon:

• Vegetable carbon, made by physically activating plant-based materials (such as coconut shells). This type is especially suited for drinking water purification and for removing volatile organic compounds (VOCs), chlorinated solvents, and trihalomethanes—common causes of unpleasant odors and tastes.
   
• Mineral carbon, derived from fossil-based raw materials, is more effective in treating complex organic substances like pesticides, aromatic hydrocarbons, phenols, tannins, chlorine, and ozone. It is commonly used in industrial applications and for air and gas purification.
   

As mentioned, activated carbon is a porous material with strong adsorptive properties—ideal for filtering and purifying water and air. Its microporous structure captures chlorine, pesticides, heavy metals, surfactants, and PFAS, improving fluid quality. In wastewater treatment systems, it helps eliminate contaminants, reduce BOD and COD, and neutralize volatile compounds responsible for odors and toxic gases.

Where activated carbon is used

Thanks to its effectiveness and versatility, activated carbon is a natural solution for treating pollutants and contributes to environmental protection. It’s used across multiple sectors:

• In water treatment, to eliminate organic contaminants and improve drinking water quality;
• In air purification, to remove volatile compounds and unpleasant odors;
• In the food and pharmaceutical industries, for filtering and decolorizing liquids;
• In industrial wastewater treatment, to handle solvents and chemical substances.
   

Activated carbon can also be categorized based on size, form, and usage:

• Powdered Activated Carbon (PAC) is particularly useful for managing industrial wastewater in chemical-physical treatment systems.
   
• Granular Activated Carbon (GAC) is effective in removing dissolved organic compounds during water treatment processes and in gas/vapor absorption. It is mainly used in drinking water treatment facilities.

All the advantages of activated carbon in wastewater treatment

Using powdered activated carbon in wastewater treatment offers many benefits that enhance the purification process. Key advantages include:

• Greater COD (Chemical Oxygen Demand) reduction: removes a higher amount of organic material from wastewater, improving treatment results and lowering COD by 55% to 75%.
• Higher BOD (Biochemical Oxygen Demand) removal: effectively reduces BOD levels—an important water quality indicator—by 78% to 98%.
• Improved ammonia nitrification: supports an environment conducive to the growth of nitrifying bacteria, enhancing ammonia removal efficiency.
• Up to 96% reduction in surfactants.
• Better settling of activated sludge: adsorption improves sludge sedimentation, reducing volume and making waste management easier.
• Improved aeration efficiency and energy savings: since activated carbon improves water quality, there’s less need for intense aeration, resulting in lower energy consumption.
• Increased overall adsorption capacity of the system.
• Reduced bulking: limits excessive biomass growth that can compromise wastewater treatment.
• Lower use of chemical additives and cost savings.
   

It’s important to note that activated carbon captures pollutants in its pores during filtration—until it can no longer adsorb new molecules. However, its adsorptive capabilities can be restored through regeneration. The main regeneration methods include:

• Thermal regeneration: carbon is heated in rotary kilns under controlled conditions. The heat decomposes contaminants, reopens the pores, and restores adsorptive capacity.
• Chemical regeneration: specific chemical agents oxidize and remove adsorbed compounds, renewing the carbon’s effectiveness.
• Biological regeneration: uses microorganisms to degrade adsorbed organic pollutants.

IDRO Group's activated carbon wastewater treatment systems

IDRO Group is a trusted provider of civil and industrial wastewater treatment systems.

The systems developed by the group are designed to handle large volumes of water and, through purification processes like biological systems, return treated water that meets regulatory standards in terms of organoleptic, chemical, physical and biological properties—making it reusable in various applications.

These systems are ideal for wastewater recovery in both industrial and increasingly, civil sectors.

As shown, the use of activated carbon in wastewater treatment significantly improves system performance, reduces operating costs, and promotes environmental sustainability. That’s why IDRO Group relies heavily on activated carbon in its wastewater treatment processes. Furthermore, for certain deodorization treatments or custom applications, IDRO has also developed air filtration systems with activated carbon, as an alternative to traditional biofilters.

IDRO Group consistently provides guidance to clients, helping them choose the most suitable wastewater treatment system for their needs. To learn more, don’t hesitate to contact us.