INFLUENCE OF QUATERNARY SALTS OF AMMONYUM ON GROWTH OF SULPHATE-REDUCING BACTERIA

Aim. To compare the growth of the monocultures of suphfate-reducing bacteria of Desulfomicrobium and Desulfovibrio genera under conditions of corrosion inhibition by biocide inhibitors – quaternary ammonium salts. Methods. Biocorrosion was analyzed by means of the gravimetric method, with the application of St3ps steel samples. The quantity of bacteria in plankton and biofilm was calculated by the method of boundary ten-fold dilutions, biogenic hydrogen sulfide concentration in medium Postgate “B” – by the iodometric titration. Results. The plankton and biofilm forms of bacteria of Desulfomicrobium sp. TC 4 strain turned out to be more sensitive to the quarternary ammonium salt containing the unreplaced phenyl radical (QAS І). This has caused both more extensive inhibition of sulphate-reducing activity and more efficient inhibition of corrosion. The plankton form of the bacteria of Desulfovibrio sp.М-4.1 strain has demonstrated a greater sensitivity to the quarternary ammonium salt with the replaced phenyl radical (QAS ІІ). Under identical inhibition of the quantity of Desulfovibrio sp. М-4.1 bacteria by the ammonium salts in biofilm, a greater reduction of sulphate-reducing activity by means of QAS ІІ compound and a greater level of protection have been observed. Conclusions. In the development and use of inhibitors-biocides in the practice of anti-corrosion protection of metal constructions it must be taken into consideration the prevalence of certain corrosive medium sulfatereducing bacteria strain. Investigated quaternary ammonium salts are more effective in preventing microbial corrosion caused by bacteria of Desulfovibrio genus.