Einfluss mechanischer Beanspruchungen auf Überschussschlammproduktion (English shop)

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Aerobic biological wastewater treatment produces large quantities of sewage sludge as a by-product. The disposal of these sludges represents a considerable cost factor in biological wastewater treatment.

Mechanical stress methods can substantially alter the structure of sewage sludges. In addition to reducing the mean particle size of the solid flocs suspended in the sludge, sufficiently high stress forces can bring about the destruction of the microorganisms contained in the sludge. This alters the biological activity of the sludges and releases intracellular substances into solution. The present work investigated the use of mechanical stress methods for reducing the amount of sewage sludge produced in biological wastewater treatment.

With the aid of respiration measurements, the influence of a mechanical treatment on biomass yield during the degradation of simple substrates was first determined. Using continuously operated wastewater treatment plants run in parallel, the influence of mechanical sludge stress on sewage sludge formation during the treatment of complex municipal wastewaters was investigated. For a deeper understanding of the mode of action of the mechanical stress, the results obtained were reproduced by means of modelling.

Through the use of mechanical stress methods, excess sludge production in biological wastewater treatment could be reduced by up to 70 %. No serious adverse effects on the overall process could be detected. The modelling showed that this reduction was primarily caused by a reduced growth of the microorganisms contained in the sludge brought about by the mechanical stress.