Kinetic study and process optimization of simultaneous biological elemental sulfur (S0) production and denitrification by using an oil-field consortium

Abstract

This study focused on the challenges of the maximum and fastest production of sulfate-free elemental sulfur through simultaneous reduction of sulfide by autotrophic denitrifying microbes. A microbial oil consortium was used to supply biomass which developed and synthetized by Research Institute of Petroleum Industry of Iran (RIPI). Having main feeds of concentrated nitrate and sulfide, this reaction was anaerobically conducted under batch conditions (8 h) and 3 different molar S/N ratios (1.75, 2.00, and 2.25). The results convinced us to look for a fourth S/N ratio (the optimal point) that our data did not show. Molar S/N ratio 1.9 was the point that the highest amount of elemental sulfur was achieved and sulfide removal rate reached the highest and fastest value (197 mg/L, 3 h) with no sulfate production. Bio-kinetics studies showed that a substrate limitation and a chemical/physical product inhibition mechanism controlled the reaction conditions. Three bio-kinetic mechanisms were investigated to predict the parameters of bio-kinetic models. Inhibition-free substrate limitation, substrate inhibition, and product inhibitions parameters were calculated and studied by MATLAB software version 17b.