Characteristics of Pyrolysis Oil as Renewable Source of Chemical Materials and Alternative Fuel from the Sewage Sludge Treatment

This paper describes the present applied research focused on pyrolysis oil as one of the three products of sewage sludge (SS) thermal treatment processing—microwave assisted pyrolysis (MAP). Specifically, the full-scale MAP unit with 3 kW magnetron and with the frequency of 2.45 GHz at low pressure conditions is in operation at AdMaS Research Centre, Brno University of Technology (AdMaS BUT). The aim of this paper is to present a chemical characterization of obtained pyrolysis oil together with the suitable analytical determination methods. Detailed characterization of pyrolysis oil from SS was realized by precipitation in n-pentane, fractionation of pentane-soluble part by column chromatography on activated silica by stepwise elution and analysis of obtained fractions by comprehensive orthogonal two-dimensional gas chromatography with time-of-flight mass spectrometric detection. Substances from several groups have been identified at the pyrolysis oil from SS sample: alkanes (110 compounds), alkenes and alkynes (184 compounds), cycloalkanes (104 compounds), aromatic and polyaromatic hydrocarbons (646 compounds), further lower numbers of alcohols, aldehydes, esters, carboxylic acids and heterocycles. The paper also presents a comparison of the above mentioned used two chromatographic methods and imply a basic ecotoxicological test—small algal screening.