Remediation of highly ferrous groundwater with volatile halogenated hydrocarbons (VHHs) contamination

Remediation of highly ferrous groundwater with volatile halogenated hydrocarbons (VHHs) contamination. The contaminated groundwater of the former tractor factory in Schönebeck near Magdeburg is conveyed to the cleaning plant via frequency-controlled well pumps and fed to a deferrisation stage in the first step. For this purpose, sodium hydroxide solution (NaOH) is added to the groundwater to raise the pH value and the water is intensively aerated to oxidize the iron contained.
Subsequently, the water passes through a sedimentation tank with a long residence time, in which the iron oxides formed settle.
As the last step of deferrisation, the groundwater is filtered in two gravel filters operated in parallel, which can be automatically backwashed.

After the deferrisation, the volatile halogenated hydrocarbons (VHHs) incl. Vinyl chloride is desorbed from the groundwater in two desorption columns and the desorption air enriched with pollutants is thermally oxidized in a catalytic oxidation plant. The resulting, acidic air is mostly recirculated in order to comply with the principle of zero emission.

After the desorption stage, the pure water passes through an activated carbon filter and is finally deposited in two infiltration basins. In addition, the pure water can also be supplied to an R-channel.