Insights

Activated carbon: reuse or disposal?

Donau Carbon
A great potential for reducing the environmental impact of the use of activated carbon lies in the thermal processing of already used, so-called spent carbon. Instead of disposal, which usually is cost-intensive, this option makes a lot of economic sense with Donau Carbon as your experienced partner.
 

Possibilities and limits

Granulated activated carbon (GAC) as well as extruded activated carbon (EAC) can, in contrast to powdered activated carbon, be reactivated by thermal treatment. With a good reactivation, the adsorption capacity of the activated carbon is almost restored and can effectively be reused. Thus, reactivation and recirculation represent a resource-saving alternative to the sole use of new activated carbon, so-called virgin carbon, in both liquid and gas phase applications.
The prerequisites for this cost-effective, environmentally friendly approach are above all that the properties or concentration of the separated organic substances make reactivation possible. If the activated carbon is to be reused for the same application, the field of application must allow the usage of a reactivate. Alternatively, we can check for the use in other, usually less demanding applications for our customers.
Accordingly, certain threshold values e.g. for sulphur compounds have to be observed on the used carbon in order to be able to ensure the protection of environment and our facilities during the reactivation process. Thus, with information from our customers on the one hand and analytical testing on the other, we can quickly decide whether reactivation is possible.
 

Reactivation - Reactivate

Depending on the previous load and the substances adsorbed, the reactivated material can regain a large part of the original adsorption capacity. In some applications, such as drinking water treatment, it has been shown in recent decades that, through multiple reactivation with Donau Carbon, activated carbons even perform significantly better than the corresponding fresh carbon for certain newly occurring substances. Thus, professional reactivation in trustful cooperation with the customer can not only offer economic and ecological advantages, but also make the product even more efficient.
Due to the mechanical stress on activated carbon over the period of use and multiple reactivation, the grain fraction of the activated carbon becomes finer and might increase the filtration resistance or pressure drop. This fine fraction is screened off after reactivation and the losses resulting from this, as well as the burn-off that occurs during thermal processing, are replenished to the original quantity supplied with the so-called "make-up" fraction of corresponding virgin carbon quality.
Thanks to thorough batch separation at Donau Carbon, it is possible for our customers to get back "exactly their" activated carbon. This is useful for instance, to continuously meet purity requirements in the application without any issues.
In applications where the customer's spent carbon cannot directly be used being a reactivate, we offer the exchange with fresh carbon. After assessing the used carbon, Donau Carbon potentially can take it back and use it for other applications in an ecologically useful way instead of disposal.
 

Proven sustainability

Water management has been a typical area for reactivation for many decades, with activated carbon applications in both drinking water and wastewater treatment. With > 1000 m³ of activated carbon per year, this sector is one of the largest in terms of volume.
Also in the food industry, such as beverage manufacturers or sugar producers, there are many committed users of this economic cycle that functions with our support.
Furthermore, there is an increasing demand and many applications in the field of air pollution control (see article TA Luft!), e.g. industrial waste air, whose spent carbons can be reactivated efficiently and used repeatedly.
 

Reactivation vs. necessary disposal

As shown in the examples given, there are many reasons for the environmentally friendly and cost-effective reuse of granulated and extruded activated carbon through reactivation. For your guidance, we would like to mention further fields of application and boundary conditions that potentially speak for or against this approach.
  • Applications      
    • Probably suitable: GAC from decolourisation of sugar solutions, removal of pollutants from juices 
    • Not suitable: Activated carbon from treatment of process waters or waste gas streams containing heavy metals 
 
  • Type and concentration of adsorbed substances
    • Probably suitable: Carbon with load of known composition, unproblematic organic substances
    • Unsuitable: Activated carbon loaded with sulphur or fluorine components, considerable load of reactive substances (e.g. acetone).
 
  • Loading level
    • Probably suitable: Material from applications with low concentrations of organic substances, e.g. EAC from odour treatment of exhaust air
    • Probably not suitable: Activated carbon with very high loading (e.g. 30%)
 
  • Purity requirements
    • Reactivate could be used for: EAC for exhaust air purification at industrial plants, granular Activated Carbon for COD reduction in groundwater remediation
    • Mostly exclusive use of virgin carbon: Production of high-purity fine chemicals and/or intermediate products
 
  • Period of use / residual capacity of spent carbon:
    • Probably suitable: Used activated carbon from a polisher stage or a "police filter"
    • Not suitable: Activated carbon from waterworks with 10 years of use (high inorganic content) and/or a residual iodine value of e.g. 200 mg/g (hardly any effective reactivation possible)
 

In summary

The reuse of granulated and extruded activated carbon by means of reactivation is both an established and modern approach that is gaining new importance in times of dwindling resources and rising expenditures for raw materials and transport. In addition to the effective and often long use of the multi-talent activated carbon, comparatively short distances for delivery and removal, a positive CO2 balance and consequently lower costs are just a few points that speak for the sustainable cycle of use, reactivation and reuse.
Donau Carbon very successfully operates reactivation plants in Germany (Frankfurt/Main) and Austria (Pischelsdorf near Vienna), where both domestic and customers from neighbouring countries have had reliably reactivated their activated carbons for decades. The more than 100 years of experience of our company in the field of activated carbon will also benefit you in this segment, accordingly.
Our reactivation questionnaire serves to collect the necessary information and, together with the analysis of samples, forms the basis for the evaluation of reactivability.
Please don’t hesitate to contact us if you are interested in reusing also your Activated Carbon.
Donau Carbon

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