Toxicity assessment of sewage sludge from municipal sewage treatment plants

The aim of this study was to assess the toxicity sewage sludge from municipal treatment plant in Bialystok. Raw sewage, primary settling tank, activated sludge, before fermentation chamber, recirculated and after dehydration on press were tested. Microtox Model 500 kit using Aliivibrio fischeri luminescent bacteria used for analyzes. EC50 index (indicating concentration toxic substances resulting a 50% reduction intensity luminescence bacterial strains used) converted into TUa units adopted as value describing tested media. obtained results showed high very ecotoxicity raw front chamber press. use tests determining flowing generated at various stages process allows detect danger associated with uncontrolled discharge system.