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Growing Plants On Oil Contaminated Land
29 June 2011
It is well known just how damaging oil can be to nature. It is also well known just how difficult it can be to clean up after a spill or contamination. Removing an oil spill or contamination from soil is hard and requires very different techniques to removing oil from water. A Lithuanian company, Biocentras, together with academic partners from Latvia and Lithuania 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.
With ever greater pressure on natural resources and legislation to protect all aspects of the environment, taking care of forests and natural landscapes is an important part of business. This importance is even clearer in the oil industry as the impact of spillage and contamination on nature can be severe.
The process of refining oil can create very high levels of contaminated soil. In the industry, this is known as 'sludge'. As might be imagined, this is different to a spill, which is hopefully a one-off event. Depending upon the situation, the soil can either be treated on location or removed and treated if it is in a sensitive area.
A Three Stage Process
A first part of the oil is washed out by using a water solution of biosurfactant, and subsequently separated. The collected oil can even be used again. The biosurfactant solution used in the washing process can be applied up to ten times and is easily biodegraded into a common natural compound.
The oil that is still bound in the soil can then be treated with specially selected micro-organisms to lower contamination concentration to a level when phytoremediation can start.
Phytoremediation consists of decreasing pollutant concentrations in contaminated soils, by growing plants able to degrade to an acceptable level or render harmless the contaminants in the soil.
In total, the process will take approximately one year, depending upon the severity of the contamination and the location. Location is an important factor in the process. As Monika Kavaliauske, manager at Biocentras, explains, “The bacteria used in the process lie dormant in negative temperatures, but then come to life as the temperature rises. However, some organisms can start to degrade oil at temperatures that are only a little more than is required to melt ice. In fact, it is much more effective in warmer climates.” With much of the world's oil coming from hot countries, she understandably sees a positive future for the technology developed in the project.
A Natural Solution
Many of the existing solutions for this problem rely on chemicals. For highly contaminated soil, larger amounts of chemicals are required, meaning that the potential for side-effects on the surrounding environment are increased. 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 to other forms of life. This provides a totally natural solution, known as biodegradation. The role of Biocentras is therefore one of optimising the use of the bacteria to provide the right amount and the best possible conditions. Not only is the process cleaner and more natural, but their internal studies suggests that it is one of the most efficient methods currently available.
The developed technology can be applied to soil contaminated by any concentration of oil or oil products. Usually biodegradation can be effective in 20 to 50 g/kg of pollution, and sometimes up to 100 g/kg. However, Biocentras manages to clean up oil sludge with up to 300 g/kg of pollutants.
The Role of EUREKA
EUREKA played an important role in this project. By helping Biocentras understand how international R&D should be performed, they renewed their laboratory which has led to an ongoing involvement in Europe's scientific and innovation markets.
This involvement includes working with partners based both in Lithuania and Latvia on this project. The Kaunas University of Technology in Lithuania provided assistance from their Environmental Engineering Institute and their Process Control Department, where they helped to optimise most of the treatment processes. While the Latvian State Institute of Wood Chemistry also played a role by participating in the development of the phytoremediation stage.
Currently, this technology is mainly in use in Lithuania. Biocentras has a number of smaller clients and one larger client – an oil refinery – which has enabled them to continue their testing and perfecting of the method. They have now successfully treated over 22,000 tons of soil.
Monika Kavaliauske sees the next phase of development as taking the process into the warmer, oil producing parts of the world. She says, “We have no clients in the Middle East and are actively looking for them. There are potential applications for most of the world and we are keen to develop it further”.