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More efficient treatment plants

Waste management has increasingly moved away from a focus on removal of waste towards recycling management with high proportions of recycling. In this way, its energy balance has also improved due to the recovery and use of energy-intensive valuable materials.

Old paper, old glass, packaging and organic waste in particular are increasingly being collected separately and re-used as valuable materials. This saves on raw materials, reduces the use of primary energy and thus also decreases CO2 emissions. A further contribution is the use of carbon-rich waste fractions as substitute fuel, for example for cement plants and industrial operations.

Through the development of improved treatment processes and plants, operators can further increase the level of energy efficiency in waste management. Composting plants process the organic waste from the bio-waste container. They consume energy in particular for the mechanical ventilation during the composting process. A new method makes it possible to also generate energy in the plants. For this purpose, with the involvement of researchers from Aachen, an innovative combination of composting and digestion has been developed: First, a screw press separates organic matter from the pre-treated organic waste. This is then used in the biogas plant to generate energy. The remaining solid fraction is composted. As a result of this pre-treatment and separation, the plants can process more material with their existing systems. At the same time, the specific energy consumption per tonne of organic waste is reduced by 10 to 15%.

The purification of municipal wastewater also requires a large amount of energy. Currently, sewage treatment plants account for almost a third of electricity costs for municipal infrastructures. Around one per cent of electricity consumption in Europe is used to operate them. In the European research project Powerstep, 15 partners are working to change this situation. The research institutes and companies aim to to convert sewage treatment plants which until now still require energy for purifying wastewater, and to turn them into energy generators. The researchers predict that the amount of electricity that can be generated is the equivalent of up to 12 large power stations, if all the European sewage treatment plants are converted and the chemical energy potential of 87,000 GWh per year can be utilised.

Projektinfo 15/2016:
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Addresses

Coordination, modification of the process chain in MT and BT
RWTH Aachen, IAR

Operator of the MBT system, test implementation
MKW

Development of exhaust air purification plant
PlasmaAir AG

Exhaust air monitoring:
Universität Stuttgart, ISWA

Info tips

Combining compost and biogas
BINE-Projektinfo 17/2014

Clean use of landfill gas
BINE-Projektinfo 11/2014

Links

powerstep.eu
Homepage of the project Powerstep

The Climate Change Mitigation Potential of the Waste Sector
Background information from the "Umweltbundesamt"