EIO - Oil-contaminated soil cleaning technology
It is well known how damaging oil can be to the nature. It is also well known how difficult it can be to clean it up after a spill or contamination. Removing an oil spill or contamination from soil is hard and requires very different techniques for removing oil from water. Lithuanian company Biocentras together with academic partners from Latvia and Lithuania has developed a technique that has so far cleaned over 22,000 tons of soil without the need for potentially harmful chemicals or genetically-modified technologies. This natural process transforms contaminated soil so that it can be used again for growing all kinds of plants.
Hydrocarbons introduction into the soil environment can occur from pipeline blow-outs, road accidents, leaking of underground storage tanks. Besides, countries which used to be part of the Soviet Union have high levels of pollutants because the then universal cleanup standards did not take into account the issue of ecology like it is today. Also, the technologically contaminated lands are becoming larger every year and the problem of developing new and improving the existing technologies for the rehabilitation of oil-contaminated soils still remains urgent.
Biocentras has teamed up with the Latvian Institute of Wood Chemistry whose researchers specialise in phytoremediation – a process where oil pollutants are degraded in selected plants. The team also included researchers from Kaunas University in Lithuania who specialise in environmental engineering and the optimisation of processes. The partners secured 0.75 million euro to develop the project as an EUREKA project.
The researchers realised that oil pollutants exist in the soil in two fractions: migrating and bounded forms. Hydrocarbons which freely migrate among soil particles are called migrating fraction. When released on the soil surface, hydrocarbons adsorb on the organo-mineral matter and on the soil particles - these are called non-migrating fraction.
It is well known that hydrocarbons can be subject to biodegradation, volatilization and leaching. The researchers worked out a set of mechanical, chemical and biological means and the bacterial oil-degrading preparations are used for decontamination of soil and water. They designed clearing sites and washing installations of soil contaminated with oil and oil products for the migrating fraction.
Removal of hydrocarbons has been performed using biological treatment. The biopreparations developed have more advantages. They enable cleaning the soil contaminated with any concentration of oil products. A separated oil products fraction can be utilized in furnace. Used biological preparations do not pollute the environment, preparations easily decompose. The biological preparation manufacturing technology is simple because of exclusion of filtration, centrifugation and desiccation stages, there is no necessity for special constructional requirements in the remediation area for the cleaning of non-migrating oil products fraction. A complex remediation technology allows to reduce the costs and to enhance the effectiveness of the remediation process. The non-migrating forms can be degraded in situ by introduction of specially selected strains of microorganisms which degrade various classes of hydrocarbon pollutants.
Thus, bioremediation which exploits the biodegradative abilities of live organisms and their attributes have proven to be the preferred alternative in the long-term restoration of hydrocarbon polluted systems, with an additional advantage of cost efficiency and environmental friendliness.
Barriers and Drivers
- usage of non-genetically-modified bacteria for contaminated soil remediation is one of the most efficient methods currently available;
- technology can be applied to the soil contaminated with any concentration of oil or oil products.
Cost reduction of contaminated soil remediation.
Promotion of natural technology for the remediation of contaminated soil
Many of the existing solutions of the problem of cleaning contaminated soil rely on chemicals. For highly contaminated soil, larger amounts of chemicals are required, which means that side-effects on the surrounding environment may increase. Other solutions use genetically-modified bacteria which have their own potential problems, including a lack of public trust.
In contrast, once the non-genetically-modified bacteria have done their work, they simply die and become food for other forms of life. This provides a totally natural solution, known as biodegradation. Not only process is cleaner and more natural, internal studies suggest that it is one of the most efficient methods currently available.
Usually biodegradation can be effective in 20 to 50 g/kg of pollutants, and sometimes up to 100 g/kg. However, Biocentras manages to clean up oil sludge with up to 300 g/kg of pollutants.