Assisted bioremediation tests on three natural soils contaminated with benzene

Abstract

Bioremediation is an attractive and useful method of remediation of soils contaminated with petroleum hydrocarbons because it is simple to maintain, applicable in large areas, is economic and enables an effective destruction of the contaminant. Usually, the autochthone microorganisms have no ability to degrade these compounds, and otherwise, the contaminated sites have inappropriate environmental conditions for microorganism’s development. These problems can be overcome by assisted bioremediation (bioaugmentation and/or biostimulation). In this study the assisted bioremediation capacity on the rehabilitation of three natural sub-soils (granite, limestone and schist) contaminated with benzene was evaluated. Two different types of assisted bioremediation were used: without and with ventilation (bioventing). The bioaugmentation was held by inoculating the soil with a consortium of microorganisms collected from the protection area of crude oil storage tanks in a refinery. In unventilated trials, biostimulation was accomplished by the addition of a nutrient mineral media, while in bioventing oxygen was also added. The tests were carried out at controlled temperature of 25 ºC in stainless steel columns where the moist soil contaminated with benzene (200 mg per kg of soil) occupied about 40% of the column’s volume. The processes were daily monitored in discontinued mode. Benzene concentration in the gas phase was quantified by gas chromatography (GC-FID), oxygen and carbon dioxide concentrations were monitored by respirometry. The results revealed that the three contaminated soils were remediated using both technologies, nevertheless, the bioventing showed faster rates. With this work it was proved that respirometric analysis is an appropriate instrument for monitoring the biological activity.

Keywords

• bioremediation, bioventing, respirometry, soils, benzene

References

1. Albergaria, J. T., Alvim-Ferraz, M.C., & Delerue-Matos, C., 2008. Soil vapor extraction in sandy soils: Influence of airflow rate. Chemosphere 73(9): 1557-1561.
2. ATSDR. (2007). Toxicological profile for benzene. Atlanta, Georgia: US Department of Health and Human Services. Available At http://www.atsdr.cdc.gov/toxprofiles/tp56.pdf.
3. Carter, M. R., Gregorich, E. G., 2006. Soil Sampling and Methods of Analysis (2nd ed.): CRC Press.
4. Carvalho, M., Vila, M. C., Soeiro de Carvalho, J., Domingues, V., Delerue-Matos, C. M., Oliva-Teles, M. T., Fiúza, A., 2010.. Extensive methodology for preliminary bioventing tests – Application to a residual granitic soil contaminated with xylene. Paper presented at the 11th International UFZ- Deltares/TNO Conference on Management of Soil, Groundwater and Sediment - ConSoil 2010, Salzburg, Austria.
5. Carvalho, M.M., 2014. Análise fenomenológica da bio-remediação de solos contaminados com compostos orgânicos - perspectiva multidisciplinar. PhD, Universidade do Porto, Porto.
6. Clesceri, L., Greenberg, A., Eaton, A., 1998. Standard methods for the examination of water and wastewater: American Public Health Association.
7. EEA. 2010. The European environment – state and outlook 2010 –soil. Luxembourg: European Environment Agency.
8. Fernandes, V. C., Albergaria, J. T., Oliva-Teles, T., Delerue-Matos, C., De Marco, P., 2009. Dual augmentation for aerobic bioremediation of MTBE and TCE pollution in heavy metal-contaminated soil. Biodegradation 20(3): 375-382.

9. Jones, J. B., 2001. Laboratory guide for conduting soil tests and plant analysis: CRC Press.
10. Lin, T., Pan, P., Cheng, S., 2010. Ex situ bioremediation of oil-contaminated soil. Journal of Hazardous Materials 176(1–3): 27-34.
11. Malina, G., Grotenhuis, J.T.C., Rulkens, W.H., 2002. Vapor extraction/bioventing sequential treatment of soil contaminated with volatile and semivolatile hydrocarbon mixtures. Bioremediation Journal 6(2): 159-176.
12. Morgan, H., Jeffries, J., Waterfall, E., Earl, N., 2009. Soil Guideline values for benzene in soil. (Science Report SC050021). Bristol: UK Environment Agency.
13. Available at http://www.environment-agency.gov.uk/static/documents/ Research/SCHO0309BPQI-e-e.pdf.
14. Singh, A., Ward, O. P. E., 2004. Biotechnology and Bioremediation – An Overview. Springer.
15. Tyagi, M., da Fonseca, M.M., Carvalho, C.C.R., 2011. Bioaugmentation and biostimulation strategies to improve the effectiveness of bioremediation processes. Biodegradation 22(2): 231-241.
16. USSLS, U.S.S.L., 1954. Diagnosis and Improvement of saline and alkali soils. Washington: United States Department of Agriculture.
17. Ward, O. P., Singh, A.,2004). Soil Bioremediation and Phytoremediation – An Overview. Springer.
18. WHO. 2000. Air quality guidelines for Europe. (91). Copenhagen: WHO Regional Publications, European Series Available at http://helid.desastres.net/en/d/Js13481e/4.1.9.html.