Bioremediation to Clean Up Oil Spills
Bioremediation to Clean Up Oil Spills. Image source: Oil is seen leaking from the Japanese-owned bulk carrier, MV Wakashio 13.
What is an oil spill?
Oil spill is the release of a liquid petroleum hydrocarbon into the marine ecosystem due to human activity such as tankers, barges, pipelines, refineries, drilling rigs and storage facilities 1. In April of 2010, the Deepwater Horizon exploded and was one of BPs biggest oil disasters that dumped over 210 million gallons of oil in the Gulf of Mexico 2. This explosion killed off over 150 endangered sea turtles and over 300 sea birds 2. Oil spills can be cleaned up through effective processes such as bioremediation, bioremediation accelerator, burning the oil, dispersants, dredging, skimming, and solidifying 3. This blog will illustrate the role of bioremediation in cleaning up and recovery the oil spill.
What is Bioremediation?
Bioremediation is a method used to treat water, soil, and subsurface material pollutants through changing environmental conditions to catalyze the growth of microorganisms and reduce the target pollutants 4. It uses microorganisms or biological agents to treat oil spills, and soils contaminated 4. Alcanivorax bacteria and Methylocella silvestris are the most effective bacteria that break down or remove oil spills 5. According to a scientific report, the strain of bacteria digests dangerous methane and other gaseous alkanes such as propane which could protect us from leaks like BP’s Gulf of Mexico oil spill in 2010 and curb global warming 5. According to Journal Nature, Methylocella silvestris is a type of bacteria that live in acidic soils and wetlands and can grow on the methane and propane that exist in natural gas 5. The reason why it can grow in methane and propane because it consists of two enzyme systems that harness both gases at once 5. Using Methylocella silvestris bacteria can reduce the greenhouse gases that can be released by oil spills and eliminate the impact of the methane and other gases. before they escape into the atmosphere 5. In addition, Methylocella silvestris bacteria can grow very fast: one bacteria can be doubled every 10 hours 5. According to Predominant Growth of Alcanivorax Strains in oil contaminated and nutrient-supplemented sea water study, Alcanivorax bacteria is playing a major role in the bioremediation of oil-contaminated marine environments 6. It is becoming a dominant bacterial population in petroleum contaminated sea water when nitrogen and phosphorus nutrients were supplied in adequate quantity 6.
Factors influencing the bioremediation process.
Bioremediation can be affected by environmental conditions such as soil moisture, soil pH, oxygen content, nutrient content, temperature, contaminants, heavy metals, and type of soil 7.
Types of bioremediation processes.
There are two types of bioremediation: ex-situ bioremediation techniques and in-situ bioremediation techniques 8. Ex-situ bioremediation techniques consist of land farming, composting, and biopiles 8. Through land farming, contaminated soil is dug and spread over the land. The soil is periodically tilled to improve aeration. Composting is a method that joins contaminated soil with non-hazardous organic amendments like manure of agricultural waste 9. Biopiles is a combination of land farming and composting, and it monitors physical losses of contaminants 9. In-situ bioremediation techniques consist of bioventing, biosimulation, bioagumentation, bioattention, and biosparging 9.
- Bioventing is a process of stimulating the natural in situ biodegradation of contaminants in soil by providing air or oxygen to existing soil microorganisms 9. Oxygen is most supplied through direct air injection into residual contamination in soil. In addition to the degradation of adsorbed fuel residuals, volatile compounds are biodegraded as vapors move slowly through biologically active soil 9.
- Biosimulation is a method where the bacteria that is present in the environment can be carried out or adding a nutrient. According to a case study when the sewage sludge was used as biostimulator 9. There was 100% reduction in petroleum hydrocarbons over 19 months, where is only 17% reduction without the sludge 10.
- Bioagumentation is adding microorganisms genetically designed to biodegrade soil contaminants 9. According to a case study in Japan, bioagumentation was used to achieve 78% reduction in oil coverage of contaminated rocks, where there is only 37% reduction without bioaugmentation 11. Using nutrients is demanded the biodegradation of oil pollution which can be used to eliminate the negative effect on our ecosystem. Nitrogen and phosphorus are the key nutrients in biodegradation for the marine oil spill 9.
- Bioattention is a method that used to add nutrients or bacteria and does not require anthropology involvement 9. The indigenous bacteria will locate the metabolic activity and work as natural attenuation 9. Biosparging is a process that uses indigenous microorganisms to break down the organic constituents in the saturated zone 9. In this process, the oxygen and nutrients get injected into the saturated zone to raise the biological activity of the bacteria or the indigenous microorganisms 9.