| Abstract [eng] |
The quantities of sewage sludge generated in the treatment plants already pose serious problems related to its storage and use. The Article 14 of the Urban Waste Water Treatment Directive 91/271/EEC specifies, “Sewage sludge from waste water treatment shall be re-used whenever appropriate. Disposal routes shall minimize the adverse effects on the environment “. Therefore, priority is given to the reuse of sewage sludge, rather than disposal it to landfills or storage plants. The analysis of scientific literature related to the quantities of sewage sludge and its chemical composition, possibilities of its use in thermal process and possibilities of residual product use in other areas as a raw material was carried out by the author of dissertation. Sewage sludge samples were collected from the major water treatment systems in Lithuania during the preparation of dissertation. After investigation of their chemical quality, author selected sewage sludge samples from a small city (Šilutė) for a more detailed research. Author designed and constructed a pyrolysis stand where he carried out thermal decomposition (pyrolysis) of sewage sludge. Solid fraction as char obtained from sewage sludge was used in experimental research on cultivation of fibre hemp (Canabis sativa L.). In order to assess the regularities of distribution of heavy metals, alkaline earth metals and alkaline metals as well as of non-metals the author carried out chemical analysis of sewage sludge, sludge pyrolysis products and gifferent parts of fibre hemp (roots, stem, leaves). According to the results author found distribution of elemental migration in the course of the application of the principle of sustainable use of sewage sludge. |
