Growth Kinetic Study in Biological Removal of Hydrogen Sulfide from Natural Gas in Batch Bioreactor

The objective of the present study was to assess the Non-structured kinetic models of microorganisms used in biological desulfurization of hydrogen sulfide from gas stream in a batch bioreactor. The microorganisms used for the removal of hydrogen sulfide were originated from a hot spring. The experiments were conducted with mixed gas at operating temperatures of 25 to 45°C with a time interval of 5h. Different kinetic models such as Monod, Logistic, Tessier, Moser and Verhulst are considered and compared by means of statistical tools. Temperature of 35°C revealed the highest regression values by fitting the experimental data obtained from measurement of bacterial growth and substrate utilization with all used models. At this temperature, the achieved regression values for Monod, Logistic, Tessier, Moser and Verhulst models were 0.95, 0.98, 0.92, 0.93 and 0.91, respectively which were reasonably acceptable. The maximum specific growth rates were also determined to be 0.315, 0.240, 0.858, 0.33 and 0.143-1 for Monod, Logistic, Tessier, Moser and Verhulst model, respectively. In addition, the hydrogen sulfide removal was 72% at 35°C. The maximum cell dry weight was 0.733 g.l-1 which achieved by Verhulst model. The inhibition coefficient was another parameter which was evaluated as a parameter affecting growth kinetics. As the gas temperature was increased to 45 °C, the inhibition coefficient may be dominated in growth kinetic. In overall, the microorganism isolated from a hot spring was capable of oxidizing sulfur compound and caused an acceptable amount of the hydrogen sulfide to be removed.