Further Evaluation of An Online Probe for Simultaneous Monitoring of Corrosion Rate and SRB Activity: Influence of FeS Surface Layer

In previous publications, a biosensor was developed by immobilizing sulphide oxidase (SO) on the graphite paste along with a co-factor 7, 7, 8, 8-tetracyanoquinodimethane (TCNQ). Facultative Actinomycete strain FR-3 was used to produce SO. The applicability of this biosensor to monitor sulphate reducing bacteria (SRB) activity online was demonstrated by correlating its electrochemical response with that of offline sulphide and sulphate measurements in anaerobic reactors. Preliminary results correlating SRB activity, as monitored by the biosensor and the corrosion rate were also presented. 

In this paper, the correlation of SRB activity and corrosion rate was further evaluated.  The corrosion rate of carbon steel (1018) in the presence of SRB in anaerobic reactors was monitored over a period of one month using the linear polarization resistance (LPR) technique. The activity of SRB was monitored online by the biosensor.  The effect of FeS film on the response of the biosensor and of the LPR probe was evaluated.  A 4-probe sensor to monitor both SRB and corrosion rate has also been presented.

Keywords - Biosensor, corrosion rate, SRB, MIC, electrochemistry, online monitoring