Dipl.-Ing.
Gunter Lehne, Dr.-Ing. Johannes A. Müller, Prof. Dr.-Ing. Jörg Schwedes
Institute of Mechanical Process Engineering, Post Box 3329, Technical University of Braunschweig, D‑38023 Braunschweig, Germany
Abstract:
The mechanical disintegration can
be used for an accelerated and improved anaerobic digestion of excess sludge.
The hydrolysis is the limiting step of this process. Mechanical disintegration
can be used to disrupt the cell walls and to cause the release of the organic
material from the cells. Particle size analysis describes the size reduction
but is not suitable for characterising the release of the organic material and
the cell disruption. Two biochemical methods were developed for these phenomena.
One of the parameters provides information about the disruption of
micro-organisms the other one gives information about the release of organic
material.
Different ultrasonic homogenizers, a high pressure homogenizer and stirred ball mills were used for disintegration experiments using various parameters. The influences of a mechanical disintegration on the particle size and of the energy intensity on the disintegration were investigated. Further investigations had to detect the influence of the solid content on the disintegration results. For sludge with a higher solid content better results in terms of energy consumption could be achieved. An optimum of the bead diameter and the stress intensity in stirred ball mills could be detected. A comparison of the results of different methods of sludge disintegration shows that the investigated ultrasonic homogenizers are inferior to a high pressure homogenizer and a stirred ball mill in terms of energy consumption.
Keywords:
anaerobic digestion, cell-disruption, mechanical
disintegration, excess sludge, disintegration devices
Origin:
G. Lehne, J. Müller, J. Schwedes (2000). Mechanical disintegration of sewage sludge, Water Science and Technology, Vol 43, No 1, pp 19 –
26, IWA Publishing, 2001and in 1st World Congress of the International Water
Association, July 2000, Paris, Book 4, pp 125 - 132