Hygienization of municipal sludge in automatically operated chamber filter presses with thermal vacuum drying.

This paper presents the state of the art of thermal vacuum drying in chamber filter presses for unattended automatic operation. The achieved results are exemplified by the treatment of the two stage digested combined primary, chemical and biological sludge created by the VEAS concept for nutrient removal from municipal wastewater at VEAS. The water removal rate in each stage of the drying process is described, with comments on the low energy needs. The advantages of one-sided heating, the capacity and the drying potential are discussed. The hygienization potential of the process is demonstrated by the effect on thermostable coliform bacteria, Escherichia coli, salmonella, the spores of sulfite reducing anaerobic bacteria, f-specific bacteriophages, the seeds of the weed, wild oat, Avena fatua, and the parasite eggs of the potato cyst nematode, Globodera rostochiensis. A more complete paper with the VEAS-concept is found on the VEAS homepage (www.veas.nu).