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Anaerobic sludge digestion with gas mixing system ("Roediger" principle)

The Challenge

Recovery of limited resources

Motivation for anaerobic sludge stabilization:

  • Inefficient operation of wastewater treatment plants means high energy consumption and high costs
  • Anaerobic sludge digestion is a good way to ensure efficient plant operation

    and at the same time achieve sludge stabilization and to improve sludge dewatering
  • With anaerobic sludge stabilization, on the other hand, a considerable

    reduction in energy consumption (~60%), in construction volume (~33%)

    and in the sludge production (~33%) is reached
  • A further advantage of anaerobic sludge digestion:
    a gas is produced, which can also be used as an energy source

Roediger® is a brand of Aqseptence Group GmbH

CNP’s Solution

Anaerobic sludge stabilization with gas mixing

The digestion process:
Freely suspended lances inject the gas above the reactor floor, allowing maximum flexibility in the shape and design of the digester.
Maintenance of the lances can be carried out during operation, emptying of the digester is not necessary.

The maximum achievable degree of organic matter degradation (oTS) depends on the type and quality of the sludge and the intensity of the digestion:
55 – 70% oTS degradation for primary sludge
35 – 50% oTS removal for waste activated sludge

The degradability also depends on the pre-treatment, e.g. by hydrolysis, the sludge age, the number of digestion stages and the process quality.


Anaerobic sludge stabilization

Advantages of the digestion process:

  • Flexible construction of reactors/digestion vessels
  • Energy production from renewable energies instead of high energy consumption
  • Hygienically improved, stabilized and reduced solids
  • Easy maintenance while the tank is in operation
  • No moving components in the digester
  • The hanging lances can be removed from the digester without
    interruption of the digester operation
  • More favourable both in terms of life cycle costs and
    total costs compared to aerobic sludge stabilization

See our references for anaerobic sludge digestion