Contaminant-reactive geocomposite mat and method of manufacture and use
Reactive geocomposite mats, and their method of manufacture, for treating contaminants in sediment, soil or water that allow the passage of essentially non-contaminated water therethrough. The geocomposite mat includes a pre-formed woven or non-woven geotextile, that is needlepunched to an outer geotextile sheet layer to provide a high loft, structurally secured, pre-formed geotextile having a thickness of about 6 mm to about 200 mm, and having, a porosity sufficient to receive a powdered or granular contaminant-reactive material, contaminant-sorptive material, or a contaminant-neutralizing material (hereinafter collectively referred to as “contaminant-reactant material” or “contaminant-reactive material”) throughout its thickness, or in any portion of the thickness across its entire major surface(s). The powdered or granular contaminant-reactive material is disposed within the pores of the previously formed, high loft geotextile mat to surround the fibers, e.g., by vacuum or vibrating the high loft mat while in contact with the contaminant-reactive material to allow the powdered or granular contaminant-reactive material to flow by gravity into the pores of the previously formed, needlepunched geotextile. A liquid-permeable outer geotextile sheet then is secured to the filled geotextile, preferably by heating upwardly extending fibers of the pre-formed geotextile mat to prevent the powdered or granular material from escaping from the geotextile during transportation and installation.
1. A reactive geocomposite article for treating contaminants in soil or water comprising:
a pre-formed geotextile mat formed by needlepunching non-woven geotextile fibers to a lower water-pervious geotextile cover sheet at a concentration of about 300 to about 450 grams of fibers per square meter of cover sheet surface area prior to adding a powdered or granular reactive material thereto, said mat having a thickness of about 6 mm to about 200 mm, wherein the non-woven fibers have void spaces that provide sufficient porosity to receive a powdered or granular reactive material and the geotextile article remains water-pervious;
a powdered or granular reactive material uniformly disposed within at least a portion of the void spaces of the pre-formed geotextile mat, secured against lateral movement and surrounding some of the geotextile fibers of said pre-formed geotextile mat;
a water-pervious upper geotextile cover sheet adhered to the upper surface of the pre-formed geotextile mat containing the powdered or granular reactive material by heat sealing the upper geotextile sheet to heat softened upwardly extending fibers of the pre-formed geotextile mat during compression of the outer geotextile sheet onto the heat-softened fibers of the pre-formed needlepunched geotextile mat to densify and confine the reactive material within the geocomposite article, between the lower and upper geotextile cover sheets.
2. The reactive geocomposite article of claim 1 , wherein the powdered or granular reactive material is selected from the group consisting of activated carbon, coke breeze, zero-valent iron, magnetite, apatite, organophilic clay, zeolite, polymeric ion exchange resins, polymeric adsorbing resins and mixtures thereof.
3. The reactive geocomposite article of claim 1 , wherein the geotextile fibers are selected from the group consisting of polyolefin, polyester, polyamide, and copolymers of any two or more of the foregoing.
4. The reactive geocomposite article of claim 2 , wherein the reactive material is an adsorbent material selected from the group consisting of activated carbon, coke breeze, organophilic clay, and any combination thereof.
5. The reactive geocomposite article of claim 1 , wherein the pre-formed geotextile, prior to receiving the powdered or granular reactive material, has an apparent opening size in the range of about 0.2 mm to about 6 mm.
6. The reactive geocomposite article of claim 5 , wherein the powdered or granular reactive material has a particle size such that at least 90% of the particles have a size in the range of about 6 mesh to about 325 mesh.
7. The reactive geocomposite article of claim 5 , wherein the powdered or granular reactive material comprises about 50% to about 99.9% by volume of the pre-formed geotextile mat.
8. The reactive geocomposite article of claim 1 , wherein the geocomposite article has 30 lb/ft 3 to 100 lb/ft 3 of powdered or granular reactive material contained therein.
9. The reactive geocomposite article of claim 3 , wherein the geotextile fibers are selected from the group consisting of polyethylene fibers, polypropylene fibers, polyester fibers and polyamide fibers.
10. The reactive geocomposite article of claim 1 , wherein the pre-formed geotextile mat is woven with non-woven fibers.
11. The reactive geocomposite article of claim 10 , wherein one of the liquid-permeable geotextile cover sheets is woven and the other cover sheet is non-woven.