Corrosion caused by sulphate-reducing bacteria (SRB) isolated from seawater nearby to Pasir Gudang has been studied. The test coupon was a AISI 304 stainless steel. Potential and corrosion rate measurements were carried out in various types of culturing solutions, with SRB1, SRB2, combination of SRB1 & SRB2 and without SRBs inoculated (sterilized). From Tafel plots a higher corrosion rate has been found in medium inoculated with SRBs than that of the sterilized medium (control). When SRBs were present in the medium, the Tafel plot shifted towards more negative values (Ecorr was shifted to much less anodic values) and increase in current density compared to that of the sterilized medium (control). Localized corrosion was observed on the metal surface, and it was associated to the SRB activity. X-ray analysis (EDAX) showed that the corrosion product has higher content of sulphur for medium containing SRBs than that of the sterilized medium. X-Ray Diffraction analysis carried out on corrosion products which showed the presence of iron sulphide. This indicates the influence of the presence of SRB in corrosion process.
The aim of this study was to determine the surface chemistry during biocorrosion process on growth and on the production of exopolymeric substances (EPS) in batch cultures of mix-strains of marine sulphate-reducing bacteria (SRB) isolated from Malaysian Shipyard and Engineering Harbours, Pasir Gudang. The EPS and precipitates were analyzed by x-ray photoelectron spectroscopy (XPS). The XPS results indicate that Fe(2p3/2) spectrum for iron sulphide can be fitted with Fe(II) and Fe(III) components, both corresponding to Fe-S bond types. The absence of oxide oxygen in the O(1s) spectrum and Fe(III)-O bond types in the Fe(2p3/2) spectrum supports the conclusion that iron sulphides are composed of both ferric and ferrous iron coordinated with monosulphide and disulphide.
The corrosion potential of AISI 304 stainless steel coupons influenced by sulphate-reducing bacteria (SRB) has been studied. Pure colony of SRB was isolated from the Malaysia Marine and Heavy Engineering, Pasir Gudang, Johor. Open circuit potential measurements were carried out in variable types of culturing solutions with SRB1, SRB2, combination of SRB1 & SRB2 and without SRBs inoculated. Results showed that the corrosion potential, Eoc increased in the presence of SRBs (in pure and mixed culture) compared to that of control. EDS analysis showed the strong peak of sulphur in coupon containing SRB cultures compared to the control. ESEM data showed that the high density cell of SRBs were associated with corroding sections of surface steel comparing with non-corroding sections for coupons immersed in VMNI medium containing SRBs.
In the attempt to isolate indigenous marine sulphate-reducing bacteria (SRB) from coastal samples, we obtained some swarm forming bacteria. The isolates were screening using Starkey’s medium and detection of main groups of SRB were carried out using commercially kits (SRB BART kits, Droycon Bioconcepts Inc., Canada). From the growth characteristic, only two isolates were strongly suggested as marine SRB. Based on the 16S rRNA gene sequence analysis these SRB were closely related and could be designated as Desulfovibrio sp. and Citrobacter freundii, with the highest sequence similarity of 98% and 93%, respectively.
Sulphate-reducing bacteria (SRB), implicated in microbiologically influenced corrosion were isolated from the deep subsurface at the vicinity of Pasir Gudang, Johor, Malaysia. Electrochemical impedance spectroscopic (EIS) study was carried out to determine the polarization resistance in various types of culturing solutions, with SRB1, SRB2, combination of SRB1 and SRB2 and without SRBs inoculated (control). EIS results showed that in the presence of SRB1, SRB2 and mixed culture SRB1 and SRB2, polarisation resistance values were 7170, 6370 and 7190 ohms respectively compared to that of control, 92400 ohm. X-ray analysis (EDS) of the specimens indicated high sulphur content in the medium containing SRBs. Localized corrosion was observed on the metal surface which was associated with the SRB activity.
Ancaman biokakisan akibat aktiviti bakteria penurun sulfat (SRB) pada saluran paip keluli karbon dalam industri petroleum boleh menjejaskan kelancaran aliran pengangkutan minyak mentah dan meningkatkan kos pengoperasian. Usaha bagi melindungi keluli karbon serta pengawalan SRB masih memerlukan kajian yang berterusan. Dalam kajian ini, keberkesanan tetrametilamonium bromida (TMB), karboksimetil trimetilamonium (BTN) dan benzalkonium klorida (BKC) bagi melindungi keluli karbon di dalam persekitaran yang mengandungi SRB diuji melalui kaedah pengutuban elektrokimia dinamik (PED) dan morfologi keluli karbon dianalisis menggunakan mikroskop elektron imbasan. Analisis PED mendapati penggunaan TMB, BTN dan BKC masing-masing berupaya mengurangkan kadar kakisan sehingga 0.13, 0.56 dan 0.17 mm/thn berbanding 8.91 mm/thn pada larutan kawalan yang mengandungi SRB. Morfologi permukaan biofilem mengesahkan kadar pertumbuhan SRB serta hasilan metabolisme bakteria ini turut mengalami penyusutan. Kajian ini menunjukkan dua mekanisme kawalan kakisan didapati berlaku iaitu mekanisme perencatan kakisan melalui penjerapan sebatian amonium kuaterner pada permukaan keluli karbon serta berlakunya proses tindak balas mitigasi sebatian ini dengan bakteria SRB. Kesimpulannya, TMB, BTN dan BKC didapati berupaya melindungi keluli karbon daripada mengalami kakisan akibat aktiviti SRB.
The efficiency of cetyltrimethylammonium bromide (CTAB) to reduce the activity of consortium bacteria consisting of
sulphate-reducing bacteria (C-SRB) has been investigated on variable concentration by weight loss test, potentiodynamic
polarization and diffusion disk methods. C-SRB was isolated from tropical crude oil of Malaysian offshore. Biofilm analysis
was also evaluated by variable pressure scanning electron microscopy (VPSEM). Weight loss and potentiodynamic
polarization analyses showed that CTAB is able to inhibit the biocorrosion process and their inhibition efficiency had
reached to 85 and 65% at 300 ppm CTAB, respectively. Increasing of CTAB efficiency as a function of concentration was
also supported by diffusion disk analysis. Biofilm analysis showed that less of C-SRB and their metabolic by-product had
been observed. It was concluded that CTAB was able to reduce the C-SRB activity and prevent biocorrosion process on
carbon steel surface.
The performance of pipeline system used in petroleum industry is crucially declined by natural microbial activities and
demanding extra operational cost. Requirement on high capability of functional substances is attracting worldwide
research interest. The aim of this paper was to study the effectiveness of benzyltriethylammonium chloride (BTC) on
reducing the activity of a consortium bacteria consisting of sulfate-reducing bacteria (C-SRB). C-SRB was isolated from
tropical crude oil and enumeration of this consortium was measured by viable cell count technique. The effectiveness of
BTC was calculated from potentiodynamic polarization method and biofilm analysis was performed by scanning electron
microscope. The viable cell count technique indicated that the maximum growth of C-SRB was approximately 160 trillion
CFU/mL at 7 days incubation period. BTC was capable of reducing biocorrosion activity due to adsorption process and
mitigating SRB species. Biofilm analysis has proven that C-SRB activity is minimized due to less presence of bacterial
growth, extracellular polymeric substances and corrosion product. In conclusion, BTC is capable to inhibit C-SRB activity
on biocorrosion of carbon steel pipeline.