THE TOXICITY OF SEWAGE FROM SELECTED MUNICIPAL SEWAGE TREATMENT PLANTS

This paper presents the results of the toxicity of crude and purified sewage from three municipal sewage treatment plants located in the Podlaskie Voivodeship. The bioindicative analysis, based on the use of the Microtox M500 analyzer and <i>Vibrio fischeri</i> bacteria, has shown high or significant toxicity in all the raw wastewater samples, according to Persoone classification. Classification by Sawicki differentiates more the results of acute toxicity tests of crude sewage, because only 66% of samples were toxic. All treated wastewater samples showed no toxicity. The obtained results of the study indicate the efficacy of removing toxic compounds in waste water treatment plants based on the classic activated sludge technology and sequential reactors (SBR) and no risk at discharging the treated sewage into the water of receivers