ABSTRACT
The main aim of sludge minimisation technologies is to remove organic material and water, hence reducing volume and mass, remove degradable material, which prevents subsequent odors and pathogen vectors, and remove pathogens. This chapter presents the state-of-the-art of current minimisation techniques for reducing sludge production in biological wastewater treatment processes. When the treated sludge is returned to the biological reactor, degradation of the secondary substrate generated form the sludge pre-treatment takes place, hence resulting in a reduction in the sludge production. The coupling of activated sludge system with intermittent ozonation has been well established. The ozone attacks the cell walls of the bacteria that make up the activated sludge causing the cells to undergo lysis. Enzymatic reactions are the basis of a novel wastewater treatment process, designed by combining the conventional activated sludge process with thermophilic aerobic sludge digester in which the excess sludge is solubilised by thermophilic enzyme.
