Sedimentation behaviour of sludge particles in a biogas tower reactor and the function of a hydrostatically pressurized sedimenter.

It was found that anaerobic sludge particles contain gas bubbles. Due to the compressibility of the bubbles, which are entrapped in the sludge agglomerates, a pressure-dependent sedimentation characteristic of the sludge particles was found and mathematically described. Enhanced hydrostatic pressure results in a considerable increase of the settling velocity of sludge particles.

Macro- and microscopic in-situ observation of gas bubbles and sludge particles in a biogas tower reactor.

Macroscopic and microscopic in-situ observation of particles and gas bubbles are used to get precise impressions of the hydrodynamical characteristics of a biologically active suspension. Moreover, values of in-situ velocities and particle densities can be gained by using these methods. The suspended anaerobic sludge revealed an extensive fibrous structure ('fur') on its surface.