Rumours: Waste activated carbon is a hazardous waste!

Activated carbon production process

Activated Carbon Production Process

Activated carbon is the most powerful weapon for treating VOC exhaust and malodorous gases. Activated carbon can adsorb (purify) most of the organic waste gas, and when it is saturated with adsorption, it can be desorbed and regenerated and used repeatedly for millions of times.

Waste activated carbon is a renewable resource

Activated carbon is a very effective product for treating VOC (Volatile Organic Compounds) exhaust gas and malodorous gases. Although many people say that activated carbon is not easy to use, even some "environmental experts" are demonizing the activated carbon, saying that activated carbon purification technology is already "outdated" technology, and it has not caught up with the times. However, why do you add an activated carbon adsorption link at the end of many new VOC technology equipment?

It can be seen that activated carbon is still a hard-to-replace VOC exhaust gas nemesis. Activated carbon can adsorb (purify) a wide variety of organic waste gases, and when it is saturated with adsorption, it can be desorbed and regenerated and reused millions of times. Unfortunately, most users are usually discarded as waste when they are saturated with activated carbon.

What a terrible waste! Just like we bought a premium household vacuum cleaner, it was discarded as waste after only one use. This example is like, "experts" say that waste activated carbon is as ridiculous as "dangerous waste".

Schematic diagram of waste activated carbon recycling

Schematic Diagram of Waste Activated Carbon Recycling

More and more propaganda about "the activated carbon purification VOC waste gas process produces hazardous waste" has become a common awareness of the public. Now we have a responsibility to tell the public (must be called out loud): The adsorption of saturated activated carbon in VOC purification equipment is not waste or garbage, these activated carbon is a resource.

Activated carbon (>10,000 RMB per ton) can be desorbed and reused,and can be used several million times. Even after millions of adsorptions have been used, the activated carbon is really at the limit of use (fragmentation, contamination, and blockage), and activated carbon is still not a waste product; at least the activated carbon can also be used as a fuel, and its combustion heat is not lower than that of coal.

The VOC exhaust gas treatment device in operation

The VOC exhaust gas treatment device in operation

Therefore, the activated carbon used in the purification equipment is not a "waste" but a resource (unless activated carbon adsorbed with highly toxic gas) and is a semi-finished product for producing activated carbon, which is at least a fuel.

Waste activated carbon recycling method

Such waste activated carbon has a high carbon content and can be recycled after treatment. Commonly used regeneration methods include thermal regeneration, wet oxidation regeneration, solvent regeneration, and electrochemical regeneration.

 

Waste activated carbon recycling and reuse flow chart

Waste Activated Carbon Recycling and Reuse Flow Chart

1、Thermal regeneration method: The used activated carbon is heated to cause the organic matter adsorbed by the activated carbon to be carbonized and decomposed at a high temperature, and finally becomes a molecule smaller than the pore diameter of the activated carbon, thereby regenerating the activated carbon. At the same time that the activated carbon is heated at a high temperature, the inorganic salt on the surface of the activated carbon can be transformed to form new micropores on the surface of the activated carbon. This method can restore activated carbon by 80%.

2、wet oxidation regeneration method: This is generally in the 200-250 ° C, 3-7Mpa high temperature and high-pressure conditions for the treatment of waste activated carbon. Most of the regeneration process is 60 minutes. Compared with the traditional activated carbon regeneration method, the method has the characteristics of low energy consumption, simple process and high regeneration rate. This technique is commonly used for the treatment of waste powdered activated carbon.

Waste powder activated carbon reuse

Waste Powder Activated Carbon Reuse

For example, it is an adsorbent substance which is highly toxic and difficult to biodegrade. The method has different temperature and pressure settings for treating different adsorbed substances to ensure the recovery of activated carbon performance as much as possible.

3、Solvent regeneration method: refers to the phase equilibrium relationship between activated carbon, solvent and adsorbed matter. By changing the temperature and the pH value of the solvent, the adsorption equilibrium is broken and the adsorbate will be desorbed from the activated carbon.

4、Electrochemical regeneration method: It is a new type of activated carbon regeneration technology under study. The method encloses activated carbon between two main electrodes. In the electrolyte, a direct current electric field is applied, and the activated carbon is polarized under the action of an electric field, one end is positive, and the other end is negative, forming a micro-electrolysis cell. A reduction reaction and an oxidation reaction may occur at the cathode portion and the anode portion of the activated carbon, respectively. Most of the organic matter adsorbed on the activated carbon is decomposed, and a small part is desorbed by the action of electrophoresis.

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