Thiosteroids in sewage sludge and its post-treatment products

Different sulphur compound derivatives from steroids were detected and quantified in the analysis of the lipidic fraction of sewage sludge and its post-treatment products, including thermally dried sludge and compost. Some steroid thiols: 5α-cholestane-3β-thiol, 24-methyl-5α- cholestane-3β-thiol and 24-ethyl-5α-cholestane-3β-thiol were detected in the gas chromatography with mass spectrometry detector (GC-MS) analysis. These three compounds, related to the thiostanol family, have only been encountered in previous studies in sea sediments. Gas chromatography with sulphur-selective flame photometric detector (GC-FPD) was used with the objective of detecting other related compounds in sludge. It allowed the detection of other compounds, whose mass spectra could correspond with the one of the steroid enethiols. The research focused on detecting the formation point of these sulphur compounds in the sludge treatment process, as well as their biodegradation resistance in the post-treatment processes. The amount of these products in the sludge was quantified using gas chromatography with flame ionization detector (GC-FID). The result of this study confirms that the identified compounds are not easily biodegradable.