Thermal decontamination of sewage sludge
¹Latvia University of Life Sciences and Technologies, Faculty of Agriculture, Institute of Soil and Plant Sciences, 2 Liela street, LV-3001 Jelgava, Latvia
²Ekosoil Ltd, 26 Academy street, UA65009 Odessa, Ukraine
³Latvia University of Life Sciences and Technologies, Laboratory of Biotechnologies, 1 Strazdu street, LV-3004 Jelgava, Latvia
⁴Earth Revival, Ltd, Maskavas street 57-3, LV-1003 Riga, Latvia
*Correspondence: Laila.Dubova@llu.lv
Abstract:
Every year a huge amount of sewage sludge is formed at municipal wastewater treatment plants. Sewage sludge contains a sufficient amount of biogenic elements and organic components, which characterizes them as possible raw materials for the production of organic fertilizers. However, direct incorporation of these sediments into the soil is impossible due to the fact that, in addition to useful organic and mineral components, they contain pathogens, viruses and helminth eggs. The aim of the study was to optimise thermal disinfection conditions for preparing of safety sewage sludge fertilizer. Laboratory studies were carried out using sediments from wastewater treatment plants of some cities. During laboratory experiments, the conditions for thermal disinfection of sediments – the thickness of the sediment layer, the air temperature in the disinfection furnace, and the treatment time of the sediment – were determined. When conducting industrial tests of a conveyor-type sediment decontamination furnace, the operating conditions of the furnace were determined, i.e., the temperature regimes of the sludge heating zone, the decontamination zone and the cooling zone, and the optimum parameters of the sludge layer thickness on the conveyor and the conveyor speed were determined.
Key words:
layer thickness, movement speed, organic fertilizers, residence time, sewage sludge, thermal disinfection