FIG. 7 is an isometric view of two cleaning pigs and two photodynamic disinfection devices in a train within the internal cavity of an industrial pipeline. The pigs use high energy light to kill biological films that cause pipelines to corrode and fail. The process was developed by BioCorrosion Solutions Inc, the first company to apply photodynamics, a technology usually used for biomedical applications, to industrial, oil and gas pipelines.
BioCorrosion Solutions engineers envision a pipeline train of environmentally responsible photodynamic pigs capable of disinfecting industrial pipelines with the same type of light now used to sterilize objects in hospitals and used by dentists to treat periodontal diseases. Microbial growth on the interior surface of industrial pipelines and processing systems is a common problem, especially in the worldwide oil and gas industries.
The damage to the pipeline structure that results from the action of these bacteria has been termed microbiologically-influenced corrosion (MIC). For example, around forty percent (40%) of the internal pipeline corrosion in the gas industry has been attributed to MIC. MIC also accounts for up to twenty-five percent (25%) of pipeline failure incidents. When pipeline failures occur the effects on the environment, workers safety, and product revenues are nothing short of disastrous. MIC is a multi-billion dollar problem in the industrial pipeline industry worldwide.
In U.S. Patent Application 20090317293, Cale Street, Joe Ridge, Nicolas Loebel and Roger Andersen reveal a pipeline inspection gauge ("pig") adapted to include a circumferential high-energy LED light source capable of killing bacteria and disinfecting the pipeline. The device may optionally further include a cartridge segment adapted to contain and to dispense the photosensitizing composition and a reservoir for collecting used photosensitizer composition.
The illuminated pig provides a powerful and yet relatively environmentally-safe method, based on photodynamic disinfection, for inhibiting and/or eliminating microbes (in both planktonic and biofilm forms) residing within pipelines.
This method does not cause structural damage to the pipelines. The method includes applying a photosensitizer composition to a predetermined interior surface area of a pipeline where microbes are located and applying light to the area at a wavelength that is absorbed by the photosensitizer composition so as to inhibit or eliminate the microbes, wherein the light is applied by a light delivery device adapted to provide light to the area.
Bacteria that are either natively resident in oil and gas or introduced after the extraction process adhere to the interior surface of the pipelines and processing systems, forming a biofilm ultrastructure on such surface. These biofilms, which are very durable and resistant to physical removal, are generally formed when colonizing microbes encapsulate themselves together in a slimy, exopolymeric substance composed of secreted polysaccharides, proteins, and nucleic acids.
Biofilms are much more difficult to eradicate by conventional means (biocides, physical/ mechanical scraping) than planktonic bacteria due to strong adherence to surfaces and physical exclusion of antimicrobial substances. Once a local biofilm has been established in a pipeline, metabolic activity of the organisms produces organic acids and gases that are harmful to carbon steel. In addition, some types of bacteria are able to metabolize sulfur and release by-products that are highly corrosive to steel.
A 2003 study by Zhu et al. used advanced molecular techniques to characterize the microbial communities harvested from standard gas pipelines. A total of 106 different bacterial DNA sequences were identified in these samples, and among those identified were species that produce nitrates (contribute to metal corrosion), species that are known contributors to biofilm formation, organic acid producers, sulfate reducers, and hydrogen consuming methanogens.
A large proportion of existing pipeline infrastructure exists in remote geographical areas. Furthermore, it is challenging to access the inside of existing lines making internal corrosion difficult to address.
Pipeline inspection gauges ("pigs") are devices that are commonly used in the pipeline industry for cleaning, eliminating blockage, separating product, and electronic mapping within difficult to access lines. There are many different types of pigs utilized for different purposes, including mandrel pigs, foam pigs, and gel pigs. In addition, "smart" pigs are used that have onboard electronics for telemetry and data collection.
Photodynamic disinfection is a technology used in the biomedical field for the treatment of bacterial infections in conditions such as periodontitis. This technology fundamentally involves the use of light energy to activate one or more photosensitizers of a photosensitizing composition so that those photosensitizers can then either pass energy on directly to a substrate/target (type I reaction), or can interact with molecular oxygen to produce singlet oxygen or other oxygen-derived free radicals (type II reaction).
Photodynamic disinfection is a technology used in the biomedical field for the treatment of bacterial infections in conditions such as periodontitis. This technology fundamentally involves the use of light energy to activate one or more photosensitizers of a photosensitizing composition so that those photosensitizers can then either pass energy on directly to a substrate/target (type I reaction), or can interact with molecular oxygen to produce singlet oxygen or other oxygen-derived free radicals (type II reaction).
These reactions mediate the non-specific killing of microbial cells primarily via lipid peroxidation, membrane damage, and damage to intracellular components. Deployed in industrial applications, major advantages of photodynamic disinfection would include the fact that it has broad spectrum activity against most known types of bacteria (including those in biofilm form), the ability to eradicate high percentages (usually >99%) of bacterial populations, and relatively small environmental impact compared to traditional chemical agents used as industrial biocides.
