Reactivation

Sometimes also called regeneration, reactivation is a thermal desorption process that volatilizes and removes the desorbed components from spent activated carbon, allowing it to be reused. The first step is Drying, where water and low boiling volatiles are removed. Then, Devolatization and Carbonization take place to remove higher boiling volatiles, causing the surface of the carbon to be carbonized. In the last half of the kiln, steam in introduced to Reactivate and open the pores on the carbon and restore its adsorptive capacity. The reactivation kiln is operated at temperatures of up to 9000 C (16500 F) which will insure removal of all volatiles in the spent carbon.

When your spent carbon needs to be changed out, there are multiple ways to handle the waste material. Landfilling and/or incineration are commonly used but are not environmentally friendly. The reactivation process recycles the spent carbon for reuse. Not only is reactivation more environmentally friendly than other options, the costs and long-term liabilities are avoided. Tetrasolv is committed to being “green” and highly recommends the spent carbon be reactivated.

The reactivation kiln is run at a slight negative pressure to insure that there are no emissions to the surrounding atmosphere. The system fan draws the off gases to a thermal oxidizer where the organics are thermally destroyed at temperatures up to 1100O C (2012O F). The gases then go to a caustic quench cyclone to cool and bring the gases to a neutral pH. From there, gases are drawn through a venturi scrubber and packed tower to remove any entrained solids and water droplets. Only neutral pH, clean water vapor is emitted through the stack to the atmosphere. The neutralized scrubber water from the process is sent to a wastewater treatment plant where it is treated and recycled for use as process water in the reactivation system.

In many applications, reactivated carbon is a cost-effective alternative to virgin carbon. Our activated carbon specialists can evaluate your application and provide recommendations on whether virgin or reactivated carbon is the most effective and economic choice

There are primarily two types of reactivation furnaces – multi-hearth and rotary kilns. Multi-hearth kilns are effective for the reactivation of pool carbons where the customer does not care whether their spent carbon is traceable or wants their reactivated carbon back. While rotary kilns can reactivate pool carbons, it is very effective in providing custom reactivation or product traceability back to the source spent carbon. Tetrasolv only utilizes rotary kilns to provide the flexibility

for our customers.

Yes, our reactivation facility in Piedras Negras, MX is specifically designed to reactivate PFAS carbons. The kiln is lined with a special refractory that is resistant to fluorides. The off gas system is designed to operate at temperatures that will destroy the PFAS molecule and the resultant acid gas is neutralized in a series of caustic scrubbers.

All spent carbon must be tested and approved for reactivation. We require a sample of the spent carbon be tested via Method 8260A, Volatile Organic Compounds – TCLP Extract along with the completion of our Spent Carbon Profile Form. Once approved, a Carbon Acceptance Number that is unique to the generating facility and waste stream will be assigned and can be used for all future

shipments.

In most cases, yes. All RCRA hazardous spent carbons must be declared as such by the generator and then tested and approved for reactivation. Any hazardous carbons will be shipped to our hazardous waste storage facility in Houston, TX where Tetrasolv will take ownership of the waste. The spent carbon will then be shipped to our Piedras Negras reactivation facility, which is permitted to reactivate RCRA hazardous waste.