Biologically produced elemental sulfur clogging induced by thiols in gas biodesulfurization systems

•Thiol addition in the gas-lift bioreactor changed the properties of sulfur particles.•The nucleophilic S8 dissolution made sulfur particles more agglomerated.•The elimination of hydrophilic groups made sulfur particles less hydrophilic.•More agglomerated and less hydrophilic particles incurred sulfur clogging behavior.•The sulfur clogging mechanism is meaningful for improving gas BDS applications.