Effectiveness of ultraviolet treatment in mitigating microbiologically influenced corrosion

The destructive effect of microbiologically influenced corrosion (MIC) of carbon steel in pipelines has been widely found in soil and water environments. Chemical biocides are normally used for MIC mitigation in pipelines. However, many problems were encountered in its application, causing biocides usage to remain controversial. Ultraviolet (UV) radiation is seen as a possible alternative for chemical biocides. Nevertheless, information on the efficiency of UV treatment and the influences of UV parameters on corrosion process is limited, thus restricting any efforts to explore the potential application of UV as a chemical biocide replacement. This study aims to identify the effectiveness of UV disinfection against MIC caused by Sulfate Reducing Bacteria (SRB) strain. The investigation utilized two different samples of SRB sources: Baram-C and ATCC7757 strains. The Baram-C SRB consortium sample was cultivated from raw crude oil gathered from one of the main trunk lines at Baram Delta Operation, Sarawak, Malaysia, while the ATCC7757 SRB sample was sourced from the American Type Culture Collection (ATCC). The observation on bacteria growth revealed that the preferred pH and temperature for the active cultivation of Baram-C and ATCC7757 strains were pH 8.5 and 37°C, respectively inside the Modified Baar’s media. The corrosion process was found more severe in biotic condition by approximately 50% based on metal loss results. The maximum corrosion rate in biotic environment was recorded at 0.3209 mm/year and 0.5042 mm/year for Baram-C and ATCC7757 strains, respectively, as compared to the 0.1791 mm/year corrosion rate in an abiotic sample. One-Factor-At-a-Time (OFAT) analysis was performed under the influence of UV time of exposure, types of UV lamps, numbers of UV lamps and treated volume. The optical density reading showed that UV treatment was able to suppress the number of bacteria up to almost 99% after 28 days of incubation. The effect on bacteria growth was similar for both strains. However, when a variety of UV treatment parameters were applied, different bacterial strains indicated different rates of metal loss. Furthermore, Response Surface Methodology (RSM) was used as a tool to determine the relationship between UV parameter and metal loss by using two different types of UV lamps (10 watts and 14 watts). The RSM models were successfully developed with R2 of 0.8990 and 0.9020 for UV lamps with 10 watts and 14 watts, respectively. ANOVA results indicate that the effects of treated volume do not depend on the level of factors contact time and numbers of UV lamp for 10 watts lamps, whereas for 14 watts lamps, the contact time and number of UV lamp do affect each other. The result also suggests that the effectiveness of UV treatment does not only depend on UV lamp’s intensity to provide optimum curing. The experimental test and numerical analysis performed in this research has provided a comprehensive understanding of the efficiency of UV treatment on the extermination of SRB strains and reduction of metal loss rates. The findings also produced a numerical measurement of metal loss rate due to SRB as a function of UV radiation. This can serve as an impetus for the transition of UV technology from its infancy level to the real-world practice of corrosion mitigation in the oil and gas industry

Ultraviolet treatment: a new potential technology to mitigate microbiologically influenced corrosion

Corrosion is a natural deterioration phenomenon caused by reactions of metals with their environment. It is also a natural spontaneous process with devastating impact towards the infrastructure (Norhazilan et al., 2011; Yahaya, 2011). There is huge challenge to mitigate this delicate phenomenon albeit the fact that it cannot be simply eliminated altogether from the deteriorating infrastructure, although with careful steps, it can be well controlled. This process has enormous financial and safety implications for many industries, including the energy industry. According to NACE International, corrosion is the deterioration of a substance or its properties as a result of an undesirable reaction with the environment (NACE, 2000). It occurs immediately when pure metals or their alloys are exposed to water

Cultivation of sulphate reducing bacteria in different media

Sulphate - reducing bacteria (SRB) represent themselves as a class of anaerobic bacteria that can reduce sulphate to sulphide for obtaining energy. This paper is aimed to detect sulphate - reducing bacteria activities using rapid detectable culture media. Two different strains of sulphate - reducing bacteria were used in this study, namely ATCC 7757 and local bacterial strain of SRB isolated from underground sample . Both strains were tested on three recommended culture media of modified Baar‟s, Postgate B and Postgate C. All three medium contained lactic acid which served to be as carbon source. The results showed that modified Baar‟s medium is the best medium for the growth of ATCC 7757 while Postgate C medium is recommended for the local SRB bacterial strain

Control of microbiologically influenced corrosion using ultraviolet radiation

Baram Delta Operation had been producing oil and gas since 1960’s and serious pipelines failure was reported in the year of 2005. The final investigation has concluded that one of the species of bacteria that has been identified to cause microbiologically influenced corrosion, specifically known as sulfate reducing bacteria (SRB) was found to be one of the potential contributing factors to the incidents. This work investigates the potential use of ultraviolet (UV) radiation to inhibit the SRB consortium that was cultivated from the crude oil in one of the main trunk lines at Baram Delta Operation, Sarawak, Malaysia. The impact of UV exposure to bio-corrosion conditions on carbon steel coupon in certain samples for 28 days was discussed in this study. The samples were exposed to UV radiation based on variations of parameters, namely: time of UV exposure; and power of UV lamp. The significant changes on the amount of turbidity reading and metal loss of the steel coupon were recorded before and after experiment. The results showed that SRB growth has reduced rapidly for almost 90% after the UV exposure for both parameters as compared to the abiotic samples. Metal loss values were also decreased in certain exposure condition. Additionally, field emission scanning electron microscopy (FESEM) coupled with energy dispersive spectroscopy (EDS) was performed to observe the biofilm layer formed on the metal surface after its exposure to SRB. The evidence suggested that the efficiency of UV treatment against SRB growth could be influenced by the particular factors studied

Influence of environmental parameters on microbiologically influenced corrosion subject to different bacteria strains

Microbiologically influenced corrosion (MIC) is capable on weakening the metal’s strength, eventually leads to pipeline leakage, environmental hazard and financial loss. Sulfate reducing bacteria (SRB) is the principal causative organism responsible for external corrosion on steel structures. To date, considerable works have been conducted in Malaysia on the mechanisms of SRB upon MIC on the marine environment instead of underground. Moreover, commercial bacteria strain represents local strain in terms of performance and behavior upon corrosion of steel structure is yet to be proven. Thus, this paper aims to investigate the influence of environmental parameters towards MIC in corroding pipeline. Two types of SRB strain were used designated as SRB ATCC 7757 (commercial) and SRB Sg. Ular (local strain) isolated from Malaysian soil. The behavior of both strains was critically compared by calculating the rate of corrosion upon carbon steel coupons in stipulated environmental parameters. Four influential parameters i.e. pH, temperature, salinity concentration and iron concentration were considered. Collected data presented and analyzed using graphical and statistical analysis, respectively. The results showed the difference of corrosivity between two SRB strains in terms of corrosion behavior upon the X-70 steel coupon. SRB Sg. Ular able to cause severe effects upon steel structure as compared to SRB ATCC 7757 due to its aggressiveness shown by the recorded metal loss data. Thus, future works related to MIC for local environment in particular, should not compromise with the type of SRB strains considered due to differences of performance of the microorganisms onto tested environment and materials

Indirect tension test of hot mix asphalt as related to temperature changes and binder types

Hot Mix Asphalt (HMA) can deteriorate and crack due to the repeated loading from traffic and change in temperature. This study is to evaluate the effects of temperature and binder types to the strength of asphalt layer. Four types of hot mix asphalt were considered in this study which were AC 10, AC 14, PMA 10 and PMA 14 and have been evaluated in the laboratory. For each type, the strength of the mixes have been compared related to different temperatures which are 25ºC and 40ºC using the Indirect Tension Test machine for resilient modulus according to ASTM D 4123 and the effect of binder types was also observed between bitumen type pen 80/100 and performance grade (PG) 76. Optimum bitumen content from Marshall Test results show that for AC10, AC14, PMA10 and PMA14 are 6.3%, 5.2%, 7.2% and 6.0% respectively. From the Indirect Tensile Modulus Test results it clearly shows that the values of resilient modulus decrease when the temperature is increase. AC10 and AC14 with bitumen 80/100 had higher resilient modulus at 25ºC compared to PMA10 and PMA14. However, at 40ºC the PMA10 and PMA14 shows vise versa. Bitumen pen 80/100 is suitable for low temperature condition because it has high resilient modulus value compared to PG76 but for high temperature, it is otherwise. From this study, PMA14 is found to be the best mix having the highest resilient modulus of all at 40ºC temperature, thus it is suggested that for Malaysia climate condition where the highest surface temperature is between 40ºC to 50ºC, PMA14 design is more suitable and will increase the pavement strength and lengthen the service time

Combination effects of ultrasound wave and biocide treatment on the growth of sulfate reducing bacteria (SRB)

Microbiologically influenced corrosion (MIC) is caused by the presence of sulfate-reducing bacteria (SRB) and is of great concern to the heavy metal industries. Inhibitors and biocides are commonly used to control the problem. Nevertheless, the solutions are too expensive and may create environmental problems by being corrosive to metals. Ultrasound wave exposure is one of the potential alternatives to biocides for the mitigation of MIC risk in pipeline system. In this work, a combination of ultrasound wave and green biocides of glutaraldehyde and ethanol has been proposed to exterminate SRB in a medium. An amount of 100 ml of Desulfovibrio vulgaris (ATCC7757) broth number 1249 was grown in 125 ml anaerobic vials at 37°C for one day followed by exposure to various mitigation methods. Results from the study show that a combination of ultrasound and biocide can effectively reduce the dosage of biocide during corrosion treatment. The effectiveness of mitigation based on ultrasound-biocide combination is better than the treatment based solely on biocide whereby the extermination of SRB was found 10 times more effective according to the reduction of cell numbers of planktonic's SRB. Ultrasound technique can provide a feasible alternative as an effective assist to chemical inhibitors and biocides for controlling MIC in a more eco-friendly manner

Corrosion of x-70 carbon steel pipeline subject to sulfate reducing bacteria

Carbon steels are commonly used as structural materials of piping systems in oil and gas industry because of their lower cost and wider availability despite their relatively lower corrosion resistance. This work investigates the preferable growth media for Sulfate Reducing Bacteria to proliferate rapidly and the effect of Microbiologically Influenced Corrosion activity towards carbon steel API 5L X-70 line pipe. Present research work highlighted that the preferred growth medium for ATCC 7757 and BARAM is Modified Baar's and Postgate C for Sg. Ular types of SRB. In addition, the corrosion rate was calculated using data based on metal weight loss experiment. The result confirmed that the corrosion rate in biotic (presence of Sulfate Reducing Bacteria) environment is much higher compared to abiotic environment (absence of Sulfate Reducing Bacteria). The pitting morphology that developed with time due to SRB activity was characterized with Field Emission Scanning Electron Microscopy and Energy dispersive spectroscopy. It shows high peak of Sulfur (S) and Iron (Fe) present after exposure to biotic compared to the abiotic sample. Field Emission Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy results show that corrosion activity due to Sulfate Reducing Bacteria will form biofilm and iron sulfide layer on the metal surface. Future research should emphasize using local strain bacteria rather than microorganisms from culture collection sample to represent the activity and the effect or impact of microorganisms from the actual sit

Corrosion of x-70 carbon steel pipeline subject to sulfate reducing bacteria

Carbon steels are commonly used as structural materials of piping systems in oil and gas industry because of their lower cost and wider availability despite their relatively lower corrosion resistance. This work investigates the preferable growth media for Sulfate Reducing Bacteria to proliferate rapidly and the effect of Microbiologically Influenced Corrosion activity towards carbon steel API 5L X-70 line pipe. Present research work highlighted that the preferred growth medium for ATCC 7757 and BARAM is Modified Baar's and Postgate C for Sg. Ular types of SRB. In addition, the corrosion rate was calculated using data based on metal weight loss experiment. The result confirmed that the corrosion rate in biotic (presence of Sulfate Reducing Bacteria) environment is much higher compared to abiotic environment (absence of Sulfate Reducing Bacteria). The pitting morphology that developed with time due to SRB activity was characterized with Field Emission Scanning Electron Microscopy and Energy dispersive spectroscopy. It shows high peak of Sulfur (S) and Iron (Fe) present after exposure to biotic compared to the abiotic sample. Field Emission Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy results show that corrosion activity due to Sulfate Reducing Bacteria will form biofilm and iron sulfide layer on the metal surface. Future research should emphasize using local strain bacteria rather than microorganisms from culture collection sample to represent the activity and the effect or impact of microorganisms from the actual site