Soil pollution is a big problem. Heavy oils such as crude oil and other heavy hydrocarbon mixtures can render land unfit for human and animal habitation for many years.

“There are more than 3.5 million contaminated sites around Europe,” says SORBENT project coordinator Danguole Draguniene. “Over half are due to oil pollution. At least EUR 1 billion is spent annually on cleaning up oil and hydrocarbons in Europe alone.”

By focusing on this environmental problem, SORBENT has developed a process that Draguniene says could lead to potential savings of EUR 8 million a year. “These savings will make a significant contribution to reducing the economic and social problems caused by heavy hydrocarbon contaminations,” she adds.  

Absorbing oil, cutting costs

Importantly, the Sorbent project aimed to develop a soil-remediation technique that can be applied in situ – i.e. without the need to remove the soil and treat it elsewhere. “Removing contaminated soil, or treating it away from the site, is very expensive and often impractical,” says Draguniene. “The solution lies in treating the soil in situ, which is where the SORBENT project focused.”

However, high contaminant concentrations, especially in cases of heavy hydrocarbon mixtures and low soil permeability, have typically limited the application of available in situ techniques. The project team sought to develop a new means of addressing this problem by combining several bioremediation techniques and improving their performance.  

Using funding secured through the EU’s FP7 programme, SORBENT deployed an innovative solution based on pulp and paper-mill waste and a bioremediation process with three integrated stages. The technique was developed to be applicable to various types of oil (including crude and heavy) in different soil profiles.

First, an innovative organic sorbent embedded with oil-digesting microbes is employed. A bacterial preparation – a mixture of microbial cells to decontaminate the soil – is then used, before the phytoremediation process (the use of plants to absorb and migrate pollution) can begin.
“Stage-one treatment is applied when initial oil concentrations reach up to 350g per kg,” explains Draguniene. “This reduces the oil concentration to as little as 170g per kg in less than 10 days. Stage two further reduces the oil concentration to between 20 and 50g per kg over six to nine months. The phytoremediation process finally reduces the oil concentration to the accepted environmental standard of 1g per kg over three to six months.”

In some cases, the stages of the SORBENT integrated technique can be used independently to solve contamination problems, depending on initial concentration, location, etc.  

A global solution to a global problem

This project could bring long-term benefits worldwide. Oil pollution is a long-standing global issue, and petroleum-based products are used in numerous industries. As production and consumption continue to increase, so inevitably do inadequate safety practices, resulting in accidents, and further contamination. In addition, vulnerable areas, such as abandoned industrial sites, former military bases and landfills, already exist and must be addressed.  

“The main consequences of soil contamination are degradation of soil and groundwater quality, negative impact on human health and risk of loss of biodiversity and biological activity. A viable and effective solution to remediate these sites at a viable cost is in itself a direct benefit to society.”

The next step will be a full-scale demonstration of SORBENT’s integrated technique to verify the viability of the solution and acquire regulatory acceptance in order to market the resulting project products. The SORBENT-DEMO project has been submitted for the next round of FP7 funding.