Decontamination in the Circular Economy
What is the objective of a circular economy?
The objective of a circular economy is ultimately to preserve resources (water, fossil fuels and raw materials). Different ways exist to achieve such a goal: ecodesign of products, energy efficiency programs, renewable energy programs and recycling from non-hazardous and hazardous waste.
Recycling of waste from its hazardous contaminants is not a new practice and is increasingly necessary to remove legacy contaminants. It has been done for many years (e.g. solvent recycling, batteries) but special care is needed.
Why does the recycling of hazardous waste require a decontamination step?
A hazardous waste can be broken down in to three fractions:
- A fraction where a recovery of energy is possible
- A fraction consisting of a material that can be recycled
- A fraction containing the hazardous contaminants which cannot/shall not be recycled
Before or during the recycling process, hazardous wastes have to be decontaminated from their hazardous unwanted fractions to protect the public, workers and the environment from exposure. This is because the industrial sectors and the public must trust that a product incorporating recycled materials/substances from waste is as harmless as a product that does not contain recycled materials/substances.
NOTE: It remains evident that HWI facilities also play an important role in the decontamination of non-recyclable waste streams. Critical substances that are destroyed in the HWI facilities encompass toxic heavy metals (like Chromium, Lead or Cadmium), toxic volatile metals like Mercury or Arsenic, or detrimental substances like Halogens (such as chlorine) or Sulphur.
Examples
Recycling of plastics
When recycling plastics, it is important to keep an eye on additives that may be present in the products, such as bromine. Plastics containing high percentages of BFRs (brominated flame retardants) should not be recycled for reuse.
Recycling of lithium ion batteries
Batteries contain both valuable metals and heavy metals and acids. Lithium ion batteries can be treated in a rotary kiln to destroy the organic components and to deliver the lithium-containing bottom ashes to specialized facilities for recycling.
Fluorescent lamp recycling
Fluorescent lamps contain valuable rare earth metals but also toxic mercury. The rare earth metals and other recyclable materials (e.g. glass, ferrous / non-ferrous metals etc.) must be safely removed without any release of mercury either to the workers or to the environment. Specialised plants exist specifically to treat these lamps and to decontaminate the waste by capturing the mercury.
Spent solvents
Some waste solvents can be distilled to produce clean components like Ethanol, Toluene etc. Specialized plants regenerate/distill these spent solvents before reuse. The concentrate from the distillation is incinerated with energy recovery enabling a safe and sound disposal of the contaminants from spent solvents.
Recycling of household appliances
When recycling household appliances like refrigerators or air conditioners, it is of utmost importance that the refrigerants (gases) are removed, since they may be Ozone Depleting Substances (ODS) or have a severe impact on our climate as Greenhouse Gases (GHG). The gas is removed with a sealed hose into a large tank. This tank will be shipped to an incinerator, where the gas will be destroyed so that it can’t leak out into the atmosphere.
What should happen to the residual fraction from the decontamination step?
As for other hazardous waste, the contaminated fraction has to be disposed of in dedicated facilities for the safe treatment of hazardous waste. Hazardous waste incineration plants are usually the best choice to dispose of this contaminated fraction because they encompass:
- Strict management procedures for safe disposal
- Skilled and trained workers for safe disposal of the fraction
- An efficient treatment process avoiding emissions to the environment
- Specific obligations from hazardous waste regulations and strong supervision from the authorities
What happens when the decontamination step is not done properly?
When the decontamination is not performed prior to the recycling activity, hazardous contaminants are simply dispersed either in the environment or in the recycled products, altering its properties and increasing its toxicity.
In conclusion
There can be no sustainable circular economy without a decontamination step. By providing a reliable solution for the sound and safe disposal of contaminated fractions, dedicated hazardous waste incineration plays a key role in a sustainable circular economy.