Final processing of sludge from biological treatment

S Final processing of sludge from biological treatment 

Even after anaerobic digestion the voluminous sludge contains a lot of water. It is thus necessary to decrease the amount of water in it and hence also its volume so that its transport and eventual further processing would become more economical. For this purpose various methods can be used, especially thickening, dehydration and drying, or eventually incineration (for details see Section 3.11). 

Dried and concentrated sludge contains many nutrients and therefore it can be well used as a fertilizer for either direct fertilization or for composting. Since it has a high content of nitrogen in comparison to phosphorus and potassium, it is recommended to add the lacking nutrients [3-6]. 

Schroeder, E.D. Water and Wastewater Treatment. McGraw-Hill, New York 1977. 

Winkler, M. In Topics in Enzyme and Fermentation Biotechnology, 8. A. Wisman (ed.). E. riorwood, Chichester 1984. 

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