Mechanical disintegration of sewage sludge

Mechanical disintegration can be used for an accelerated and improved anaer obic digestion of excess sludge. The hydrolysis is the limiting step of thi s process. Mechanical disintegration can be used to disrupt the cell walls and to cause the release of the organic material from the cells. Particle s ize analysis describes the size reduction but is not suitable for character ising the release of the organic material and the cell disruption. Two bioc hemical methods were developed for these phenomena. One of the parameters p rovides 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 parameter s. The influences of a mechanical disintegration on the particle size and o f the energy intensity on the disintegration were investigated. Further inv estigations had to detect the influence of the solid content on the disinte gration results. For sludge with a higher solid content better results in t erms of energy consumption could be achieved. An optimum of the bead diamet er and the stress intensity in stirred ball mills could be detected. A comp arison of the results of different methods of sludge disintegration shows t hat the investigated ultrasonic homogenizers are inferior to a high pressur e homogenizer and a stirred ball mill in terms of energy consumption.