Ex situ bioremediation of a soil contaminated by mazut (heavy residual fuel oil) – A field experiment
Research highlights
► First field-scale (approx. 600 m3) study of the ex situ bioremediation of mazut-polluted soil. ► 94% of the initial total petroleum hydrocarbons were biodegraded. ► 96%, 97% and 83% reductions for the aliphatic, aromatic, and NSO-asphaltene fractions, respectively. ► Confirmed biodegradation of pristane and phytane which mean that these compounds are not suitable as markers for following a bioremediation process. ► Use of zymogenous microbial consortia for re-inoculation.
Introduction
Mazut is a low quality, heavy (chain length 12–70 C atoms) residual fuel oil (ASTM D396-09a, 2009, ISO 8217, 2005). In the United States and Western Europe mazut is blended or broken down with the end product being diesel. In Eastern Europe, however, mazut is used as a source of heating fuel. The long-term storage and use of mazut can leave hydrocarbon residues in the reservoir itself, with a high content of different mechanically-derived contaminants and water in the reservoir; this can potentially lead to dangerous pollution of the living environment (particularly soil) during cleaning, when there is a serious threat to underground water.
Among numerous technologies used for cleaning up contaminated areas, the most common is bioremediation (Forsyth et al., 1995, MacNaughton et al., 1999), using zymogenous microorganisms (Langer et al., 2004). Some defined bacterial species are able to degrade, to a limited extent, all hydrocarbons present in heavy fuel oil or oil sludge (which are complex mixtures of alkanes, aromatic hydrocarbons and NSO-asphaltene fractions) (Bossert and Bartha, 1984). A consortium of microorganisms can conduct these complex processes of degradation, while at the same time, being more resistant, on average, to changes in the ecosystem than just a single microbial species (Brenner et al., 2008).
While there is significant information in the literature about the microbiological degradation of defined individual hydrocarbons (Singh and Ward, 2004), there is significantly less data about the biodegradability of some commercial petroleum products, including mazut and heavy residual fuel oil (McMillen et al., 1995, Sugiura et al., 1997, Nocentini et al., 2000, Iturbe et al., 2004, Delille et al., 2008). Studies published to date on the bioremediation of mazut and heavy residual fuel oil contaminated soils are laboratory-based, using model systems, and have indicated the potential of bioremediation for stimulated self-cleansing (Boronin et al., 1997, Díez et al., 2005).
Environmental factors play a vital role in the bioremediation of soil contaminated with heavy oil deposits (Dibble and Bartha, 1979). The most significant physical and chemical characteristics of soil which can influence the process of bioremediation are: density and water retention capacity, pH, moisture and carbonate content, temperature, availability of oxygen and carbon-based nutrients, nitrogen, phosphate and potassium, as well as the concentration of heavy metals (Rogers et al., 1993).
Although the most suitable criteria for optimizing the bioremediation process are known (control of temperature, aeration, particle size, moisture, macro and micronutrients in the mass to be composted, C/N ratio of the materials, etc. (Singh and Ward, 2004), so that the microbial activity necessary for treating this organic matter can be encouraged, very few published studies have attempted to treat mazut or heavy residual fuel oil on an industrial scale (Marín et al., 2006, Jiménez et al., 2006).
Our previous field-scale application showed that the oil pollutant mixture in the soil treated by ex situ bioremediation behaved in a complex way: different degradation rates and time evolutions were observed for fractions of the hydrocarbon mixture characterized by different molecular weights and structures (Jovančićević et al., 2008a, Jovančićević et al., 2008b, Beškoski et al., 2010). We also concluded that a stable microbial community had been formed after initial fluctuations and that the microorganisms which decompose hydrocarbons were the dominant microbial population at the end of the bioremediation process, with a share of more than 80% (range 107 colony forming units (CFU) g−1) (Milic et al., 2009).
The current study was conducted in order to determine if our previous laboratory-scale and smaller field-scale study (Jovančićević et al., 2008a, Jovančićević et al., 2008b, Milic et al., 2009) (100 m3) could be successfully up-scaled (Beškoski et al., 2010), and to determine the dynamics of field-scale ex situ bioremediation of soil contaminated with mazut, achieved by zymogenous inoculated microflora, including the degradation of differing hydrocarbon fractions.
We consider this to be the first field experiment designed to study the possibility of using bioremediation for treating a soil contaminated with heavy residual fuel oil such as mazut and mazut waste material. Key design considerations for bioremediation of soil contaminated with heavy hydrocarbons are intensive aeration achieved by mixing, biostimulation of zymogenous microbial consortia, re-inoculation of microorganisms that consume hydrocarbons and also having a control polluted soil for monitoring.
Indicators that are critical to the success of an ex situ biopile application for treatment and remediation of a heavy oil contaminated soil and that should be monitored are total petroleum hydrocarbon (TPH), moisture, pH, bulk density, water holding capacity (WHC), organic and inorganic carbon, nitrogen, available phosphorus and potassium as well as microbiological parameters such as total chemoorganoheterotrophs (TC) and hydrocarbon degraders (HD).
Section snippets
Mazut and mazut sediment-polluted soil
The mazut-polluted soil (PS) was excavated contaminated soil from an energy power plant which, due to a break-down, had been polluted with mazut and sediment from a mazut reservoir for a year.
Preparation of the zymogenous consortium of microorganisms
A consortium of microorganisms was obtained from PS by enrichment in 200 mL volumes of mineral medium (10 vol.%) (Löser et al., 1998), containing mazut (2 g L−1) as the only energy and carbon source in Erlenmeyer flasks (1 L).
Suspensions of the microbial consortium were used to seed four Erlenmeyer flasks (5 L),
Results and discussion
Key parameters for monitoring effectiveness of bioremediation are reduction of TPH and number of HD microorganisms as crucial indicators of degradation and utilization of hydrocarbons.
Acknowledgments
This work was supported by the Ministry of Science and Technological Development of the Republic of Serbia under Grant Nos. ON 142018B and TR 20131B.
References (42)
- et al.
Degradation of mazut by selected microbial strains in model systems
Process. Biochem.
(1997) - et al.
Engineering microbial consortia: a new frontier in synthetic biology
Trends Biotechnol.
(2008) - et al.
Highly efficient pilot biopiles for on-site fertilization treatment of diesel oil-contaminated sub-Antarctic soil
Cold Regions Sci. Technol.
(2008) - et al.
Bioremediation of a soil contaminated by hydrocarbon mixtures: the residual concentration problem
Chemosphere
(2000) - et al.
Developments in the analysis of petroleum hydrocarbons in oils, petroleum products and oil-spill-related environmental samples by gas chromatography
J. Chromatogr. A
(1997) - et al.
Comparison of oil composition changes due to biodegradation and physical weathering in different oils
J. Chromatogr. A
(1998) - et al.
Petroleum pollutant degradation by surface water microorganisms
Environ. Sci. Pollut. Res.
(2006) - ASTM D396-09a, 2009. Standard Specification for Fuel Oils. ASTM International, West...
- et al.
Change of isoprenoids, steranes and terpanes during ex situ bioremediation of mazut on industrial level
J. Serb. Chem. Soc.
(2010) - et al.
The fate of petroleum in the soil ecosystems
Methods for measuring hydrocarbon biodegradation in soils
The effect of environmental parameters on the biodegradation of oily sludge
Appl. Environ. Microbiol.
The Prestige oil spill. I. Biodegradation of a heavy fuel oil under simulated conditions
Environ. Toxicol. Chem.
Bioremediation: when is bioaugmentation needed?
Cited by (116)
Challenges and opportunities for low-carbon remediation in the Niger Delta: Towards sustainable environmental management
2023, Science of the Total EnvironmentMicrobes and marine oil spills: oil-eating bugs can cure oily sea sickness
2022, Advances in Oil-Water Separation: A Complete Guide for Physical, Chemical, and Biochemical ProcessesMicrobes as an effective tool to mitigate emerging pollutants
2022, Relationship Between Microbes and the Environment for Sustainable Ecosystem Services, Volume 2: Microbial Mitigation of Waste for Sustainable Ecosystem ServicesRole of genetic engineering in microbe-assisted phytoremediation of polluted sites
2022, Advances in Microbe-assisted Phytoremediation of Polluted SitesPreliminary investigation and neural network modeling of palm oil mill effluent as a potential bio-stimulating organic co-substrate in hydrocarbon degradation
2021, Environmental ChallengesCitation Excerpt :Therefore, the processes of bioremediation that have received global recognition consist of the degradation of various forms of environmental pollutants such as hydrocarbon (HC) through the catabolic activities of various microorganisms (Beskoski et al., 2011, Ani and Chukwuma, 2020). The bio-stimulation protocol of bioremediation has received wide acceptance as it generally involves the systematic addition of organic and/or inorganic nutrients which in most cases are deficient in the HCCS (Beskoski et al., 2011, Soleimani et al., 2013). Awari et al. (2020) combined goat manure and fish waste as a bio-stimulating organic nutrient and showed that the combination of these organic nutrients was able to increase microbial biomass and soil nutrient with time.
Study on the assessment of humification processes during biodegradation of heavy residual fuel oil
2021, Science of the Total Environment