Occurrence of plant and fecal steroid and their evolution during co-composting of sewage sludge and lignocellulosic waste

Steroid composition change during six months of co-composting of sewage sludge and palm waste was studied using Py-GC/MS. The main steroids identified were C-27-C-29 sterenes and stanols, 5 beta-cholesta-3-one, cholesta-3,5-diene and 2 thiosteranes. Except for thiosteranes and some of the C-27-C-29 cholestenes, the relative concentrations decreased during co-composting due to microbial degradation. Plant 5 alpha-cholestanol, 24-methyl- and ethyl-5 alpha-cholestanols were accompanied by fecal 5 beta-cholestanol and 5 beta-cholestanone. Some of the sterenes and cholesta-3,5-diene were formed by pyrolysis of bound forms of stanols and cholesterol, respectively. Sulfurization occurred during co-composting and increased with time. The process affects cholestanol and campestanol of plant origin leading as pyrolysis products to thiocholestane and thiocampestane (with the 5 alpha (H) configuration), respectively, and to the corresponding sterenes. The change in steroids during co-composting is positively correlated with the physico-chemical parameters of mature compost, especially C/N and NH4+ / NO3- ratios. (C) 2015 Published by Elsevier B.V.