Instead of traditional ex-situ methods such as dig and dump and dredging, EKOGRID in-situ electro kinetic oxidation technology was chosen for the site to reduce the costs of remediation and avoid disturbances to the environment.
Polluted water embankments and bottom sediments are challenging remediation targets, yet cleaning them is extremely important because the damage propagates in the aquatic ecosystem easily.
The full remediation effect was reached and verified quickly. In just three months from the start of the project, the embankments of the pond were verified cleaned.
After 12 months of the remediation process the laboratory tests showed green light also for the bottom sediments; the aliphatic hydrocarbons and PAH compounds had been removed from the site.
When the toxic aliphatic hydrocarbons and PAH compounds decomposed from the sediments, also the organic material within the sediment decomposed.
Lignin, which is one of the most abundant and slowly decomposing components of dead vegetation, started to react and decompose in the sediment. Because of decomposed lignin, the mud layer in the bottom of the pond drastically condensed. As a result, the pond became deeper with solid bottom and improved water quality.
The size of the polluted stormwater pond is approximately 4,000 square meters. Because the water depth varies between 0 to +2 meters depending on the rain fall, the fuel oil had been permeated into the embankments and the bottom sediment of the pond.
A pump and treat system installed at the site had not been able to clean the pond, and thus EKOGRID in-situ remediation solution was installed on the polluted area.
The installed system consisted of 150 vertical electrode rods, which were pushed one meter into the sediment and coupled together with horizontal steel rods. One EKOGRID control unit was set up to control the remediation process.
The effectiveness of the remediation was followed by regular samples taken from nine locations within the area and analyzed by Eurofins Laboratories.
The cleaning process was fast and efficient. Embankments reached the target in three months and the sediment within a year.
The project also verified the EKOGRID solution’s ability to condense muddy sediment to improve water quality in general.
As a conclusion, the successfully completed project in Ängelholm in Sweden again verified that the EKOGRID in-situ remediation solution is capable of composing and removing oil based hydrocarbons such as diesel heating oil, quickly and cost-efficiently.
Because of remediation methods such as the electro kinetic oxidation, the aliphatic hydrocarbons are completely oxidized and decomposed, eventually leading to a total mineralization of the treated soil material.
In this case, the content of aromatic hydrocarbons was very low. Because of the remediation, the rings were opened and aliphatic compounds were formed.
The results showed a very strong increase in non-toxic aliphatic hydrocarbons, which provide nutrients for the micro-flora in the sediment and in turn improved the water quality in general.