Soil Remediation

Causes of oil leaks

Solvents are considered the most common contaminations of the soil. Oil leaks may occur at service stations, factories as well as private homes when filling the tanks. In addition, corrosion and mechanical damage of the tanks cause oil leaks.

The contamination problem, as described above, was discovered relatively recently. New standards for double skin or safety basins were established. A proper investigation in Denmark found over 35,000 areas contaminated by oil leaks. Even very low concentrations of oil can contaminate the ground water and cause environmental smell hazards.

Soil remediation by the VOC (Volatile Organic Compound) Burner

Soil is often tight which prevents the oil leaks from penetrating deeper into the ground. It is therefore possible to suck the oil back, remove it from the soil and burn it. The oil can be removed by using drilled holes with installed perforated pipes. First, the contaminated area is mapped to determine how widely and deeply oil is distributed in the ground. The holes will be drilled appr. 22 m from each other. All pipes are connected to the" sucking pumps" with filters to separate sand and water from any gas present.  The gas will be taken up by the VOC incinerator which oxidizes the evaporated oil.

In the beginning of the process the hydrocarbon concentration is very high; typically about 25g/Nm3. The high concentration requires the gas to be diluted. The concentration goes down after a few days reaching levels between 1 to 2 g/Nm3. It continues to drop during the process and there is no need for further dilution. When the hydrocarbon concentration reaches levels close to zero, the sucking process can be stopped. The total remediation program usually takes 8-12 months.

The process is fully automatic. Only temporary control after a start up phase is needed. The control can be done by using a Cell phone or a computer.

The capacity of the Smart VOC RB type remediation burner is 300-500 Nm3/h. The entire system can be installed into a 10 feet container.

Advantages of using Catalytic Remediation

An alternative system is based on the absorption of hydrocarbons in activated carbon. This method is cheap to buy but expensive to use. If the soil contains 10,000 kilograms you will need about 30,000 kilograms activated carbon. The market price of activated carbon is approximately 55,000 Euros plus costs for treating the carbon before use. The price is double compared to the catalytic oxidation using the VOC Burner.

Another alternative is thermal oxidation. This process has even higher operational costs than catalytic oxidation. The reason is a very low hydrocarbon concentration which requires three times more added energy.