Treating residual waste safely, recovering energy and resources
Not all waste can be prevented, reused or recycled. EEW thermally treats non-recyclable residual waste and uses the energy contained in the waste to provide electricity, district heating and process steam.
Thermal treatment also generates emissions and residues. Managing and monitoring these is an integral part of the process. At the same time, secondary raw materials can be recovered from the materials that remain after treatment.
The following sections explain how EEW addresses climate impacts, pollutants, emissions and residues.
Taking a differentiated view of greenhouse gas emissions and avoided emissions
The thermal treatment of residual waste generates greenhouse gas emissions. These originate from both fossil and biogenic components of the waste. EEW measures and reports the greenhouse gas emissions associated with its business activities.
At the same time, the energy contained in residual waste is used to provide electricity, district heating and process steam. Depending on the specific application and the energy mix used as a reference, this energy can substitute fossil-based energy generation. Recovering metals from bottom ash can also avoid emissions compared with the extraction and processing of primary raw materials.
EEW accounts for such avoided emissions separately. They are not deducted from the greenhouse gas emissions associated with our business activities and therefore do not reduce EEW’s reported carbon footprint.
Further information on our greenhouse gas inventory, the calculation methods used and our climate-related metrics can be found in our sustainability reporting.
Treating pollutants in a controlled manner and removing them from material cycles
Residual waste can contain pollutants that should not enter further material cycles. During thermal treatment, organic pollutants are destroyed under the process conditions required for this purpose. Other pollutants, including mercury and other heavy metals, are bound or separated.
The resulting residues are subsequently treated, recovered or disposed of according to their properties. In this way, pollutants can be removed from further material cycles in a controlled manner.
Cleaning flue gases in multiple stages
The thermal treatment of residual waste generates flue gases, which are cleaned before being released through the stack. EEW plants use multi-stage flue gas cleaning systems for this purpose.
Depending on the plant and the processes used, different components of the flue gas are specifically reduced or separated. These include dust and particles, acidic gas components such as hydrogen chloride and sulphur dioxide, as well as mercury and other heavy metals. Dioxins and furans are also separated during flue gas cleaning. Processes for reducing nitrogen oxides are also part of flue gas treatment.
The specific technologies and cleaning stages used depend on the individual plant. Substances separated during flue gas cleaning are bound in residues and subsequently treated, recovered or disposed of according to their properties.
Making emissions data transparent
Thermal waste treatment plants are subject to statutory and permit-specific emission limits. Compliance is monitored continuously or through regular measurements, depending on the relevant emission parameter.
We publish emissions data for our plants on the respective location pages, where you can find the data for each individual site.
Recovering materials and enabling circular use
Various residues remain after thermal treatment. These include bottom ash and residues from flue gas cleaning.
Bottom ash, also referred to as incinerator bottom ash, contains mineral components and metals. During subsequent processing, metals can be recovered and used as secondary raw materials. Depending on their properties and the applicable requirements, mineral components may also be suitable for recovery. EEW works with specialised partners in this area.
Another approach concerns the treatment of sewage sludge. At our sewage sludge mono-incineration plants, sewage sludge is treated separately from other waste. This produces phosphorus-containing ash that provides a basis for the future recovery of phosphorus. Mono-incineration therefore creates an important prerequisite for making the phosphorus contained in sewage sludge available for future use.
Not all residues generated during thermal treatment can be recovered. Residues that are not suitable for further use due to their properties are treated and disposed of in accordance with the applicable requirements.
Further information on our residue volumes, recovery routes and targets can be found in our sustainability reporting.
How flue gas cleaning works
Flue gas cleaning consists of several coordinated process stages. The technologies and combinations used depend on the technical configuration of the individual plant.
Separating particles: Filtration and separation processes remove dust and other solid particles from the flue gas.
Reducing acidic gas components: Substances such as hydrogen chloride and sulphur dioxide are bound and separated using suitable reagents.
Separating heavy metals and organic trace pollutants: Flue gas cleaning processes reduce substances including mercury and other heavy metals as well as dioxins and furans.
Reducing nitrogen oxides: Specific processes reduce nitrogen oxides (NOx) by converting them into other compounds under controlled process conditions.
After cleaning, the flue gas is released through the stack. Compliance with the emission limits applicable to each plant is monitored through continuous and regular measurements.