Decline in Sulfate Reducing Bacterial Consortia by the Sulfur Oxidizing Bacterial Activity

Abstract

In anaerobic environment, dominant sulfate reducing bacteria (SRB) consortia are found to cause many serious problems to the oil such as sour oil, hydrogen sulfide (H2S), and metal corrosion. They are obligatory anaerobes using sulfate, thiosulfate and sulfites as final electron acceptors and use organic acids or alcohols as a carbon source. In the aerobic system, other dominant niches are sulfur-oxidizing bacteria (SOB) playing role in biological oxidation of hydrogen sulfide. These SOB convert H2S into elemental sulfur (S0) by partial oxidation. Since the levels of reduction and oxidation are dependent on the oxygen concentration. In the condition of limited oxygen, sulfate generated by SOB can also be contributed to the reduction of oxygen which encourages SRB proliferation in anaerobic environment. In this research, we were interested to manage the conditions to control the dominant niches by management of oxygen levels. In the experiment, the concentration of sulfate concentration, acidity, sulfide were determined to understand the microbial activity. The results showed after cocultures of SRB and SOB niches in the present of oxygen, the activity of SRB was prevented since a decrease in H2S product but an increase in sulfate concentration were observed. This revealed a promising niches of SOB isolates in the presence of oxygen and active in high sulfide removal. These data indicated the situation suitable for either SOB or SRB community is dependent on oxygen concentration. The management of SOB community can be used as an alternative method to remove contaminating H2S from the system.