PROSPECTS AND PROBLEMS OF SLUDGE PRE-TREATMENT PROCESSES

J. A. Müller

 

Institute of Sanitary Engineering and Institute of Mechanical Process Engineering,
Technical University of Braunschweig, Post Box 3329, D-38023 Braunschweig, Germany
E-mail: jo.mueller@tu-bs.de, http://www.tu-bs.de/~jom

 

Abstract:

Pre-treatment processes have been developed in order to improve subsequent sludge treatment and disposal. Disintegration of sludge solids in the aqueous phase changes the sludge structure and solubilizes organic matter. This paper provides an overview of the applications of wet disintegration in wastewater and sludge treatment. Applied disintegration techniques  such as mechanical, thermal, chemical and biological methods are briefly described. The methods are compared regarding energy consumption, operational reliability and stage of development for application on wastewater treatment plants. Mechanical and thermal methods  appear to be most suitable at this stage. The effects of pre-treatment on subsequent sludge treatment processes and the wastewater treatment are described. The performance of various methods is assessed. For the improvement of stabilization, mechanical and ozone treatment as well as thermal treatment perform best. Dewatering can be enhanced by thermal and freeze/thaw treatment. All methods show positive effects in the reduction of the number of pathogens. Pre-treatment leads to secondary effects like the generation of recalcitrant compounds and odor, which is mainly a problem of thermal and ozone treatment. The evaluation of capital and operational costs is difficult, because of the lack of full scale experience. Especially thermal, freeze/thaw and biological treatments can be realized at low costs if the conditions are appropriate. Nevertheless, the economic efficiency has to be investigated critically for each individual application.

 

Keywords:

pre-treatment, disintegration, biodegradability, dewatering, sludge handling and disposal

 

Origin:

J. Müller (2001). Prospects and Problems of Sludge Pre-Treatment Processes, IWA - International Water Association, Sludge Management Entering the 3rd Millennium- Industrial, Combined, Water and Wastewater Residues, Taiwan Conference, Taipei, 25.-28. March 2001, pp. 111-118