SORA. Klaerschlammreduzierung mittels Ultraschall Abschlussbericht

Improved waste water purification results in increased accumulation of sludge. Even new legislation increases the demand for ecologically friendly methods of sludge reduction. Up to now ultrasound disintegration of sludge to improve its biodegradability is known on a small (laboratory) scale only. Within this research project raw and excess sludge of the sewage plant at Bad Bramstedt (pop. equivalence 85.000) was treated with a newly developed sonoreactor for high-performance ultrasound disintegration and digested at fermenters (sewage digesters) with different residence times. Dependent on residence time and duration of ultrasonic treatment excess sludge was reduced by up to 40%. This corresponded to an effective overall reduction of sludge by 15%. Ultrasonic treatment of excess sludge can reduce digestion time by a factor of 4. Foaming sludge can be reintegrated into the digestive process after short ultrasonic treatment during which total destruction of flake structures can be achieved thus improving depositional characteristics tremendously. Economically and ecologically operational use of sonoreactors does already make sense for treatment of foaming sludge. In spite of investment costs and high amount of energy required, utilization of sonoreactors for disintegration of sludge might already make sense today for new sewage plants or for plants to be reconstructed since ultrasonic treatment allows for smaller scale sewage digesters or alleviates the need to increase sewage digester volume (= construction of a new sewage digester). (orig.)SIGLEAvailable from TIB Hannover: F98B1917+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman