Cleves-Salmorth sewage treatment plant

Heat-generating wastewater treatment facility ensures greater efficiency

Sewage treatment plants are amongst the largest consumers of electricity in the municipal sector, accounting for an average share of 20 per cent. The city of Cleves (German: Kleve) has therefore set itself the target of redesigning the local sewage treatment plant to operate in a way that is climate-neutral and energy self-sufficient. A building block towards achieving this target is the expansion of the existing process steps to include a heat-generating packaged wastewater treatment facility, which has been planned here from the beginning as a unit with a range of different modules. Not only is this development linked to a higher level of efficiency in terms of the production process, but it will also have a special impact on climate protection. With the help of the heat-generating wastewater facility, the sewage treatment plant will be able to reduce its CO2 emissions by 3,621 tonnes per year in total.

The city of Cleves aims to be climate-neutral by 2050 and is pursuing a comprehensive climate protection strategy. The municipal sewage treatment plant is of particular importance in this respect since the processes involved are particularly energy intensive. The plant alone accounts for 8,600 tonnes of CO2 emissions per year – which amounts to 18 per cent of the city’s total emissions. The integration of an innovative heat-generating wastewater facility is intended to make the sewage plant operate more efficiently. This addition will not only result in a reduction of the plant’s total electricity consumption – the compact digestion system produces sewage gas, which can be used in the future as a renewable source of energy to produce power and heat in a CHP plant. In this way, part of the energy required at the sewage treatment plant will be generated on site. An innovative sludge recycling plant is also part of the new machinery and makes it possible to produce high-quality phosphate fertilisers from the accrued sewage sludge. The integration of these components, in particular, represents an innovative and efficient solution for future-oriented sewage treatment plants.

Engine for progress:

  • The first optimisation of a heat-generating packaged wastewater treatment facility as a system
  • Innovative interlinking of the production of sewage gas and phosphate fertiliser
  • Early focus on the production of fertilisers that will conserve resources
  • CO2 emissions cut by 3,261 tonnes

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Photo: USK

The city of Cleves’s planned sewage treatment plant will operate in a way that is climate-neutral and energy self-sufficient in the future.

Energy efficient and self-sufficient in terms of heating

With the addition of the heat-generating wastewater facility, the sewage treatment plant will be expanded by various modules, which will be linked together in the process. These consist of a compact digestion plant (sewage sludge digestion), a screw compactor (sludge dewatering), a low-temperature belt dryer (drying sewage sludge) and the plant for decentralised sewage sludge recycling. In the compact digestion plant, digester gas (sewage gas) is produced, which can be used as a renewable source of energy to generate power and heat in a new CHP plant. The heat produced here and in the plant for sewage sludge recycling is used for the processes involved in the sludge treatment, so that this part of the sewage treatment process can be operated self-sufficiently in terms of heat. In the future, two more primary sedimentation basins will extract energy-rich primary sludge, which will be fed into the digestion system. This means that the intake load at the next stage of the treatment process is reduced by 25 per cent and the energy consumption is lowered to a similar extent.

Conserving resources through the recovery of phosphate

With the sophisticated integration of the innovative technology in the sludge recycling process within the packaged wastewater treatment facility, the city is also designing the sewage treatment plant at an early stage to produce high quality fertiliser in a way that is future-oriented and resource efficient. A phosphate fertiliser is produced from the pure sewage sludge here, ensuring that this important nutrient is returned to the natural cycle. With the recovery of phosphate via the newly integrated facility, the city of Cleves is thus making a further significant contribution to the sustainable management of resources and the environment.

Photo: USK

Partners and sponsors

  • Umweltbetriebe der Stadt Kleve AöR
  • Stadt Kleve, insbesondere Fachbereich Tiefbau
  • Gemeinde Bedburg-Hau
  • Gemeinde Kranenburg
  • Städte- und Gemeindebund NRW
  • Kommunal Agentur NRW GmbH
  • Bundesministerium für Umwelt, Naturschutz, Bau und Reaktorsicherheit (BmUB)