Effectiveness of hybrid soliwave technique in mitigation of microbiologically influenced corrosion

The applications of Ultraviolet (UV) radiation as an alternative approach to toxic chemical biocide for disinfecting bacteria such as Sulfate Reducing Bacteria (SRB) to mitigate Microbiologically Influenced Corrosion (MIC) in steel pipeline systems are already established. However, in the case of poor quality effluents, the UV radiation becomes less effective. Recently, Ultrasound technique (US) was observed to be attractive as pre-treatment for various types of physical disinfectant such as UV radiation. Hence, this research aims to investigate the performance of hybrid treatment known as Hybrid Soliwave Technique (HyST) to control MIC activity. The investigation was performed by utilizing two SRB strains namely pure strain ATCC 7757 and isolated SRB species from local site from BARAM, Sarawak. The study focused on three types of disinfection experiments which were individual UV radiation, individual US irradiation and HyST treatment, a combination of US and UV. Turbidity measurement and SRB cells were recorded to determine the most preferable pH and temperature for both SRB strain to proliferate actively. Corrosion rate was determined using weight loss method by exposing the steel coupons to SRB activity and abiotic sample. Both graphical and statistical analyses were performed using a statistical software (SPSS 20), to investigate the significance of SRB remaining cell number and SRB towards the corrosion rate of untreated and treated steel coupons. This study revealed that the preferable pH and temperature for ATCC 7757 and BARAM to grow actively in the Modified Baar’s Media is at pH of 8.5 and temperature of 37˚C. While, the corrosion rate of steel coupons in ATCC 7757 and BARAM strain was 0.5058 mm/year and 0.3209 mm/year respectively. These rates were at least 44% higher as compared to the corrosion rate in abiotic sample (0.1791 mm/year). The treatment results show that the HyST treatment succeeded to reduce the number of active bacteria, hence reducing the corrosion rate by 55%. The results proved that the presence of SRB increased the corrosion rate significantly compared to samples without SRB. The present study also revealed that the HyST treatment is an effective and a feasible approach in substituting toxic chemical biocides in controlling the MIC problems especially for the pipelines. Overall, the HyST treatment shows better efficiency against individual UV radiation treatment

Hybrid treatment of ultrasound and ultraviolet radiation to mitigate microbial corrosion on API 5L X70 carbon steel

The destructive effects of microbial corrosion of carbon steel in pipes have been widely found in soil and water environment. Numerous studies have proven the ability of ultraviolet (UV) radiation as an alternative technique to substitute hazardous chemical biocides in disinfecting microbes for pipelines system. Unfortunately, the radiation efficiency is hindered due to the presence of suspended particles in the environment. Moreover, the UV treated microbes would undergo photo-reactivation which allows the damaged deoxyribonucleic acid (DNA) to be repaired or rejuvenated. In order to counter these drawbacks, a recent study recommended that combining UV radiation with ultrasound (US) technology can led to its irreversible damage inflicted to the microbe’s cell wall. However, information on the efficiency of the integrated treatment between US and UV and the influences of its variables on corrosion process is scarce and limited, thus restricting any efforts to explore the potential application of UV combined with US as an alternative for chemical biocide replacement. Present study aimed to investigate the optimal performance of integrated treatment using US with UV technology in controlling microbial corrosion caused by sulfate reducing bacteria (SRB) strain. The investigation utilized one pure SRB strain known as Desulfovibrio vulgaris (ATCC 7757) and focused on static treatment condition. Four experimental stages were involved in order to attain the research objectives and aim. The metal loss of API 5L X70 carbon steel coupon was recorded systematically, then the corrosion rate of steel coupon in untreated and treated environment was determined using weight loss technique. The corrosion rate of steel coupon in biotic sample was found approximately 34% higher than abiotic sample. A total of 438 steel coupons were used throughout research duration. Based on screening design, the findings have successfully identified the most influential variables of the hybrid treatment which are US exposure time, UV exposure time, distance of UV lamps to sample, amplitude of US, and volume of sample. In addition, interactions between the variables were also considered when performing the hybrid treatment. Subsequently, one microbial corrosion mitigation empirical model was derived sequential to the hybrid treatment using response surface method (RSM) with correlation coefficient (R2) of 72%. Regardless of the moderate value of R2, since it has statistically significant predictors, it is still possible to draw important conclusions about how changes in the predictor values are associated with changes in the response value. Results also have confirmed that the hybrid treatment outperformed individual UV and US treatment based on the reduction of corrosion rate by approximately 50%. On the other hand, the simultaneous (US+UV) reactor set-up performed effectively with corrosion rate 0.0108 mm/year as compared to 0.0174 mm/year by non-simultaneous (US-UV) reactor set-up. These corrosion values are much lower than the control sample and non-hybrid treated sample. Valuable findings from present research shows promising future for non-physical corrosion treatment since this can serve as an impetus for the transfer of the integrated technology from its infancy level to the real-world practice of corrosion mitigation in the oil and gas industry

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

Statistical investigation on anaerobic sulphate-reducing bacteria growth by turbidity method

In oil and gas industry, corrosion due to activity of microorganism is one of the main factors, which contribute to catastrophic structural failure. Previous study always linked Sulfate-Reducing Bacteria (SRB) upon the mechanism of Microbiologically Influenced Corrosion (MIC), as the major contributors. In this study, mechanisms of SRB genus D. vulgaris in terms of bacterial growth under influence of environmental factors were investigated. The growth of pure strain ATCC 7757 and SRB isolated from the soil in suspected areas in Peninsular Malaysia were investigated by using turbidity measurement. Results from the study were analyzed statistically to show the significant influence due to various environmental factors. The results agreed that variation of each environmental parameter tested gives strong influence upon bacterial growth for SRB strain individually

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

APPLICATION OF ULTRAVIOLET RADIATION TO CONTROL MICROBIOLOGICALLY INFLUENCED CORROSION: A CASE STUDY ON SOIL SAMPLE FROM MANGROVE

Microbiologically influenced corrosion (MIC) is significant to the presence of microorganisms such as sulfate reducing bacteria (SRB) in the deterioration of metallic and non-metallic materials. Bacterial chemical biocides are commonly used to disinfect microorganism effectively. Yet, the practice has some negative impact on the environment since the chemical content may cause pollution. A laboratory experimental investigation was conducted to explore the performance of Ultraviolet (UV) radiation in exterminating SRB as an option to replace biocides usage. The morphologies of the isolated Sg. Ular SRB used in this study were related to Desulfovibrio species. An experimental work was conducted in determining the optimum pH and temperature for the SRB to grow before disinfection purposes. The experimental result showed optimum growth for respective SRB were at pH of 8.5 with temperature recorded at 37˚C. UV radiation with wavelength of 254 nm was utilised to disinfect the microorganism. SRB samples were exposed to UV radiation for one hour and left incubated for 21 days. It was found that the percentage of metal loss in a sample exposed to UV radiation was lower compared with untreated sample. Results from the study revealed that UV has a potential as a viable option for SRB disinfection purposes and may be further developed to reduce the consumption of chemical biocides in pipeline maintenance scheme