Refrigerated solvent is fed through a cooling jacket around an essential element extraction vessel. After circulating through the cooling jacket, the solvent is re-chilled and at least some of the solvent is passed into the extraction vessel, in which essential elements dissolve into the solvent. Downstream of the extraction vessel, after adsorbent media treatment, the extracted oil and solvent mixture is filtered, in a chilled state, through one or more filtration units. A filtration unit may be a system of vertically oriented filters of decreasing pore size sealed and insulated from the atmosphere. Pressurized gas is used to force the oil and solvent through the filters. Each filter stage has a removable lid, which provides convenient access for replacing the filter cartridge without disturbing the thermally insulated sidewalls of the filter stage.