One of the problems faced by the enterprise Karelvodokanal LLC is the disposal of sediments (excess slidge) formed as a result of wastewater treatment.
Sludge is aggregated in the course of dehydration in two stages and stored in sludge basins.
The use of this sludge as soil/subsoil is impossible due to the presence of parasites (worm eggs, etc.), as well as due to the structure of the sediment. When stored outside, hard crust forms on the surface of the pile - so called sludge cake, under which the sludge retains a viscous jelly-like structure under the influence of polymers applied at the stage of dehydration.
In order for the structure of the sludge to change and the parasites to die naturally, sludge must be stored outside for at least 3 - 5 years.
In order to determine the methods (techniques) of sludge disposal acceptable for average scale sewage treatment plants, Karelvodokanal LLC takes part in the international project KA 4020 " "Reaching congenial region through valorisation of municipal and industrial waste waters and sludge. ""Waste Disposal" program of cross-border cooperation Karelia 2014-2020.
Project partners are: University of OuluU, the University of Eastern Finland, Petrozavodsk state University, JSC ECOLAN (Finland), JSC PKS Vodokanal (Petrozavodsk). The purpose of the project is to identify and carry out pilot activities on Sortavala WWTP on the utilization of sediment and methods of its processing in order to use sludge as soil/subsoil for landscaping of the city, in nurseries and in suburban areas.