The effect of industrial biocides on sulphate-reducing bacteria under high pressure

Abstract

This study was undertaken to determine the influence of temperature (20, 37, and 50°C) and pressure (1, 100 and 200 atm) on a strain of sulphate-reducing bacteria (SRB), isolated from an oil reservoir in Alaska. The effect of different concentrations (100, 200 and 500 ppm) of biocides isothiazolone (ITZ) and formaldehyde (FA) on planktonic population of SRB was tested in order to determine the efficacy of biocides under these conditions. The highest bacterial growth rate was 0.26±0.03 h−1 at 37°C under pressure of 100 atm. Statistical evaluation showed that although both temperature and pressure had exerted an effect on bacteria by significantly increasing their growth rate; temperature rather than pressure had greater influence on bacterial proliferation. The effectiveness of both FA and ITZ in controlling planktonic populations of SRB was comparable except at 37°C/200 atm, under which conditions FA proved to be more potent. The effectiveness of both biocides decreased with an increase in cell number, as observed at 37°C/100 atm.