Meldorf WWTP, Germany




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Combatting of foaming formation in digester by ultrasound technology

Brief Snapshot of the Plant

  • Design Capacity: 72,000 PE
  • Actual Capacity: 40,000 PE
  • Biological waste water treatment: P-Elimination, Intermittent denitrification (regulated by Auqualogic, Passavant Intec), Secondary clarification, Downstream P-precipitation (Fe3+), Filtration
  • Sludge treatment: No primary sludge, Thickened waste activated sludge, Co-Fermentate
  • Thickened waste activated sludge: Disc concentrator
  • Anaerobic sludge stabilisation: 1 digester (2.000m, mesophilic), 2 digester(2.000m, used mainly as storage tank), HRT: 22 days
  • Degradation rate of volatile solids (VS): 61% as per cent of dry solids before test phase
  • Digested sludge dewatering: Chamber filter press
  • Sludge disposal: Agriculture


Objective of the ultrasound disintegration system

  • Combat foaming sludge in the digester by destroying filamentous microorganisms
  • Fail-free digester performance and trouble-free biogas utilization
  • Increase volatile solids degradation


Preliminary trial of the ultrasound disintegration system

  • Test phase of three months (September - November 2004)
  • Total TWAS flow was treated with 1 ULTRAWAVES US unit 5 kW


Current WWTP Meldorf Sludge Flow Sheet


Results of the trial

  • Combat foaming sludge in digester
    - Foaming was stopped shortly after implementation of the ultrasound system
  • Fail-free performance and trouble-free biogas utilization
    - Continuous addition of co-fermentate is possible
    - Trouble-free utilization of increased biogas production
  • Volatile solids degradation
    - Reduction of the volatile solids from 61% to 45%


Reduction of volatile solids since implementation of Ultrasound technology


Payback time

Based on these results, the payback time for the ultrasound system installation is calculated with 3 years.


Full-scale Installation

Since May 2005 the ULTRAWAVES ultrasonic system is implemented and. And since is in operation 24 hours per day.


Installed ultrasonic reactor


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