Sewage sludge disintegration

Definition

"Sewage sludge disintegration" is the stressing of sewage sludge through external forces. Physical, chemical and biological forces are applicable for the disintegration. The effect of these forces is the decomposition of the flocculent structures within the sludge and/or a breaking-down of the micro organisms embodied in the sludge.
This procedure leads to a distinct decrease in particle size of the sludge and also to a release of organic sludge components into the liquid phase.

Objective

The purpose of sewage sludge disintegration is the release of cell components in order to stabilize the sludge more rapidly and more extensively as well as a reduction of foam problems.
The actual operational areas of sewage sludge disintegration are the improvement of the anaerobic stabilization, provision of internal hydrogen sources for the denitrification process and a better sedimentation of the sludge, especially of bulking sludge.

Development

In Berlin, Mannheim and Braunschweig the first systematical investigations of the disintegration of sewage sludge have been started almost at the same time, but independently, in 1990/91. The promising results lead to the project: "Improved Degradation of Sewage Sludge by Cell disintegration", at the Technical University of Braunschweig, supported through the German Research Council. Through the common work of four University institutes a significant contribution to the basic research of this new process of sludge treatment has been made.

Workshops and conferences

Because of the desire to bring together the growing number of work groups for a scientific exchange we hosted a workshop in March, 1996 with the topic: "Mechanical sewage sludge disintegration and anaerobic degradation behavior". The workshop provided an opportunity for a scientific exchange within a small group for scientists and other practical users who are working actively in this field. The lively and fruitful discussion has lead to a repeat of the workshop in March, 1998.

The situation in 1998 changed in comparison to 1996. The representatives of communities and associations, the managers, the planners and others were asking us to offer an informative conference about this topic. This shows how large the need is for information regarding possibilities and limits of this new technology. We satisfied the need for knowledge during the first conference concerning this topic at the TU Braunschweig in March 1998 , titled: "Sewage sludge disintegration - research and application". The proceedings of this conference are available in German language only.

ATV-workgroup

In June 1998 the new ATV workgroup 3.1.6 "Disintegration of Sewage Sludge" was found. The members are from Universities, associations and consultants. The goal of the group is to inform all ATV members about backgrounds, chances and limits of sewage sludge disintegration.
At first the workgroup focused on the treatments of mechanical disintegration. Thermal, chemical, physical and biological treatments will be part of the work and they will be more deeply discussed in the future. Within the workgroup there is going to be an evaluation of the different mechanical disintegrations. Aspects, like technical realization, implementation into the sewer plant processes, specific energy consumption and the economic efficiency are investigated.
In this course the knowledge, acquired in pilot plant and full scale, will be accumulated, to offer information for potential users. The homepage of the ATV-workgroup gives detailed information and a large section of references in the field of sewage sludge disintegration.

Research

Since 1991 have the institutes of "Mechanical Process Engineering" and "Sanitary Engineering" of the TU Braunschweig been researching the field of sewage sludge disintegration.
A number of research works have been produced. In the following is given a list of the topics of these works.

         Comparison of different methods of Sewage Sludge Disintegration

         Improvement of the anaerobic degradation behavior

         control of bulking and foaming sludge

         influence of dewatering process