ABSTRACT
The main reason of that is the growth of the world population and implementation of the formal regulation in the field of the wastewater treatment and sewage sludge management. For example, in the European Union (EU) the implementation of the Urban Wastewater treatment directive 91/27/EEC led to 50% increase in sludge production by the year 2005, that is 10 million tons annually. Additionally, The EU Landfill Directive 99/13/EC obliges to reduce the biodegradable waste deposits to landfills. Both Directives cause a strong pressure to present new possible ways of sludge management (Werle and Wilk 2011).
