Ricupero liquidi sotto vuoto |
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Vacuum-Enhanced Liquid Recovery (IEG VLR) process is an innovative technology underpinned by a detailed knowledge of how hydrocarbons actually behave in the subsurface. Using IEG VLR maximum recovery of free-phase product floating on top of the groundwater can be achieved quickly and cost effectively using a specially adapted well screened above the groundwater surface combined with one of several possible hydrocarbon recovery systems. By applying a low negative pressure to the well, the floating free product moves horizontally, together with soil air containing hydrocarbon vapours, into the well where they accumulate. Dependent on the properties of the soil, the diameter of the sphere of influence of a VLR well can extend for up to 20 metres. The application of negative pressure causes upwelling of the air/water level inside the recovery well where the free product layer mounds and forms a reservoir, into which an IEG phase-separation device is lowered.By then applying a low negative pressure, only the free phase hydrocarbon product is extracted via the phase-separation system, where it is transported to the surface and collected in a tank for onward disposal. Because groundwater is not extracted, which would otherwise cause a cone of depression and smearing of the unsaturated zone, hydrocarbon contamination is not exacerbated. The system offers many possibilities. For example, a significant increase in the recovery rate may be achieved by the re-infiltration of treated process air via infiltration wells which are normally installed radially around the extraction well. The IEG VLR system can be easily converted into a bioventing system to further enhance remediation of residual hydrocarbons by microbiological degradation. Depending on the extent of the contamination, it is possible to install several VLR-wells in a line to intercept and recover hydrocarbons from a plume, without the usual disturbance and inconvenience of installing a long trenched recovery system. Depending on the properties of the soil, it is possible to design such a multi well system to ensure that the spheres of influence overlap, providing an impassable hydrocarbon recovery barrier. Advantages
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