Biopurification has been employed to purify PH3 offgas. However, the removal efficiency is not very high owing to the PH3 biotoxicity. In this study, the reactive oxygen scavenger was introduced for the first time to enhance the PH3 biopurification. The process could be divided into two main stages, biosorption and bioconversion. The capacity of PH3 adsorption was 0.062 mg per gram of biomass; however, the final conversion of PH3 depended on the microbial metabolism. The oxidase activities increased when fulvic acids and tea polyphenols were added to the bioreactors denoted as R1 and R2, respectively. The two systems exhibited lower O-2(-center dot) contents, alleviating the excessive oxidation of intracellular organic matter, and the content of malondialdehyde in microbial organisms largely decreased. The PH3 removals in R1 and R2 fluctuated in the range of 79.4-82.7 % after 20 d, and were considerably higher than that in the control. A pathway via reactive oxidation scavenger enhancement of PH3 biopurification is proposed to clarify the correlation between the oxidation stress and biochemical process. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.