Determination of polycyclic aromatic compounds and heavy metals in sludges from biological sewage treatment plants

Abstract

The procedure of the analysis of polycyclic aromatic hydrocarbons (PAHs) and their derivatives in the sludges from biological sewage treatment plants has been worked out. The analysis included isolation of organic matter from sludges, separation of the extract into fractions of similar chemical character, qualitative–quantitative analysis of individual PAHs and their nitrogenated and oxygenated derivatives. Liquid–solid chromatography, solid-phase extraction and semipreparative band thin-layer chromatography techniques were used for the separation. Capillary gas chromatography–mass spectrometry analysis of the separated fractions enabled identification of more than 21 PAHs, including hydrocarbons which contained 2-6 aromatic rings as well as their alkyl derivatives, 10 oxygen derivatives, 9 nitroarenes, aminoarenes and over 20 azaarenes and carbazoles. Using the capillary gas chromatography–flame ionization detection technique the content of 17 dominant PAHs was determined. The content of heavy metals was determined in investigated sludges with the use of atomic absorption spectrometry. The concentrations of the respective metals could be ranked in the order Cd<Co<Ni<Pb<Cr≤Cu<Mn<Zn<Fe. The sludges were analysed for the first time in Poland in view of their possible utilisation in agriculture and in cultivating dumps of coal mine wastes, taking into consideration the contents of toxic organic pollutants and heavy metals.