Sustainability and activated carbons – production, use and disposal

Essen, 13 December 2024 – Activated carbon is a sustainable product used in a variety of industries. Sustainability encompasses three equally important dimensions: economic efficiency, social justice and ecological viability. These dimensions are inseparably linked and can work together ideally in the production of activated carbon.

Activated carbon is a carbonaceous, highly porous adsorbent with a wide range of applications. It is used to clean gases and liquids, for example in drinking and wastewater treatment, the desulphurisation of biogas and natural gas, the removal of heavy metals from flue gases and the retention of volatile organic compounds (VOCs) in industrial exhaust air. Various raw materials are used to produce activated carbon, including stone coal and lignite, peat, wood, nut shells (especially coconut shells), palm kernels and polymers.

CarboTech, a leading manufacturer and distributor of activated carbons, is increasingly focusing on sustainable processes and products. Innovative processes such as the globally unique fluidised bed process efficiently reactivate the activated carbon, extending its lifecycle and reducing its carbon footprint. This, in combination with the company’s own solar system, load profile optimisation and speed control in production, as well as a fleet of electric pool vehicles, significantly reduces the company’s carbon footprint.

After use, there are various options for reusing or disposing of the used activated carbon. Depending on the type of contamination and the physical properties of the adsorbent, thermal recycling may be necessary, but it is also possible to regenerate and reuse the materials. Examples from the production, use and disposal of activated carbon will be used to illustrate its sustainability potential.

Production

Various carbonaceous materials can be used to activate activated carbons. Thermal or chemical activation reduces the material to a carbonaceous framework. This results in intertwined and nested planes of graphitic carbon. These structures are interspersed with voids that form the pore structure of the materials and lead to the large internal surface area that is typical for activated carbons.

Hard coal as a raw material for activated carbons is not sustainable. Underground mining of coal can bring prosperity to the miners, but it is associated with significant health and environmental risks. Environmental risks include the pollution of groundwater by mine water and the permanent alteration of the landscape through subsidence. The health risks for miners include respiratory diseases caused by rock dust, methane gas and dust explosions, as well as injuries caused by falling rocks and handling machines.

Wood-based activated carbons are a possible sustainable alternative. By charring and activating wood, technically equivalent products to other raw materials can be obtained. However, the use of very aggressive chemicals in the production process and the often unclear origin of the woods used are problematic.

Due to its rapid growth rate, bamboo is an attractive alternative. Recent research projects are investigating the possibility of producing activated carbons sustainably from native woods, with a focus on adding value to plant residues such as green waste.

The most sustainable solution is activated carbon made from coconut shells and palm kernels. These raw materials are available in abundance as waste products from the cultivation and processing of coconuts, nuts and palm kernels. The low utility of these materials, even heating with them is often unattractive, and the use of the same plants over several years leads to a product that is environmentally advantageous. Short transport routes – the activation furnaces are usually close to or on the plantations themselves – and the use of biogas from the fermentation of waste products for thermal activation can further enhance this advantage. Overall, activated carbons made from coconut shells and palm kernels offer an environmentally friendly and sustainable solution that makes both ecological and economic sense.

The thermal activation of activated carbons is an energy-intensive process, which in many cases still uses conventional natural gas firing. Here, too, CarboTech is a pioneer in the efficient use of energy. The waste heat from the exhaust gas after activation is extracted by several heat exchangers and used for other purposes. This means that activated carbons can be dried, buildings heated and surplus energy fed into the Essen district heating network without increasing primary energy consumption.

Use

Activated carbons are used to separate substances from gaseous or liquid phases. Activated carbon makes a significant contribution to sustainability through this separation of substances. In the field of biogas, desulphurisation enables smooth power generation and heat recovery, which means that a larger proportion of renewable energies can be used. In the biogas upgrading process, biomethane is produced in natural gas quality and fed into the gas grid. Activated carbons clean exhaust air streams so that VOCs, heavy metals and other pollutants do not enter the environment. In water treatment, activated carbons remove pollutants before they enter surface waters, groundwater or drinking water. Particularly persistent organic pollutants such as PFAS, micro-impurities and drug residues can be effectively captured and retained, preventing them from entering the environment and coming into contact with living things.

The use of activated carbon also contributes to the reduction of greenhouse gas emissions. For example, the desulphurisation of biogas can reduce the emission of hydrogen sulphide and sulphur dioxide by up to 99%. In water treatment, activated carbons can remove up to 90% of micro-pollutants.

With its CarboTech ReNew product range, CarboTech has assumed a position of global leadership in the area of sustainability. This product portfolio offers a sustainable product for almost every application that can match the adsorption performance of conventional activated carbons.

Disposal or reactivation?

The sustainability of a product is essentially determined by its lifespan in relation to the resources used in its manufacture. In some cases, the disposal of the activated carbon used is unavoidable, especially in the case of high levels of heavy metals, sulphur or halogens. Here, careful consideration must be given to how the waste should be treated.

In most cases, however, the activated carbon can easily be reactivated after use. If the gas phase mainly adsorbs low to medium volatile hydrocarbons, almost complete regeneration is possible. Activated carbons used for water treatment can also be reactivated as long as they comply with national limits, such as the German Drinking Water Ordinance. This can at least double the lifespan of the activated carbon, if not multiply it.

As a leading supplier of activated carbon, CarboTech relies on innovative reactivation processes that are superior to conventional methods. CarboTech’s unique fluidised bed process enables particularly efficient reactivation in which the activated carbon particles are treated optimally. This results in a maximum adsorption capacity comparable to that of fresh material.

Currently, thermal reactivation usually involves the use of conventional heat sources to generate hot gas. Switching to hydrogen from renewable sources offers additional potential for making the process more sustainable. CarboTech is a pioneer in this area and is continuously working to optimise its processes and make them more sustainable.

By selecting a suitable reactivation process, such as the technically superior fluidised bed process compared to conventional rotary kilns, product properties similar to those of the fresh material can be achieved after reactivation. CarboTech’s processes are not only more efficient, but also more environmentally friendly, which sets them apart from competitors.

Conclusion

The examples given above are intended to shine a light on the possibilities offered by activated carbon in the area of sustainability. The CarboTech Group has a wealth of experience in the field of activated carbons, built up over decades, and is happy to assist you in all matters relating to sustainability. Thanks to a broad product portfolio with various sustainable raw materials, an established supplier network with high requirements in terms of social, safety and environmental standards, as well as our own reactivation plants with fluidised bed processes, we can provide the highest quality in a sustainable manner, as is also certified by the continuously renewed EcoVadis award.