METHOD AND DEVICE FOR DECONTAMINATION OF GROUND

Abstract: A method and a device for decontaminating soil on the spot from harmful substances. In the soil one or several horizontally drilled holes (10) are arranged debouching into the ground surface. In the hole a chord (16) is inserted in form of a hose or a number of interconnected sockets, in which reactive sorbents are stored. The chord (16) remains in the ground during a sufficiently long period for achieving a desired decontamination of the soil.

Description: METHOD AND DEVICE FOR DECO TAMINΛTION OF GROUND The present invention relates to a method for decontaminating soil on the spot from harmful substances. The invention also relates to a device to accomplish the method. There arc today over the entire world existing large areas with contaminationcd soil. Grounds being contaminated by harmful substances, such as heavy metals, but also PCB, chlorinated hydrocarbons, etc. Thus, it has become a large field of research to develop technologies to remove poisons from the soil and a number of different methods has been proposed. A method has i.a. been proposed, by which the poisoned soil is removed and transported to a decontamination facility, in which the soil is cleaned and thereafter restored to the ground area, where the removal took place. Such a method and the matching device become very complicated and thereby expensive to accomplish, the facility becoming i.a. automatically mobile to be usable in ground areas to be cleaned, or the soil has to be transported to a stationarv facility far from the ground area. Also chemical methods have been developed to clean contaminated grounds, microemulsions then being pressed into the ground to wash the decontaminations away from it. Even this last mentioned method becomes complicated due to the aggregates pressing down the microemulsions and pumping these again out of the contaminated ground. The main object of the present invention is to present a method for cleaning grounds, in which the drawbacks of already known methods might be avoided and which in a simple and inexpensive way provides a cleaning of contaminated grounds. Another object of the invention is to provide a device, by means of which contaminated grounds can be cleaned in a simple and inexpensive way. These and other objects and advantages of the invention arc achieved by providing it with the characteristics specified in the claims to follow. The invention will be described herein below more in detail in connection with the drawing, providing an embodiment of a device for accomplishing the method according to the invention. Figure 1 shows a cross section of a ground area to be cleaned. Figure 2 shows a plane view along the line 11-11 in figure 1. Figure 3 shows a section along the line Ill-Ill in figure 1. As shown in figure 1 a horizontal hole 10 is drilled in the ground to be cleaned, this being achieved bv means of a technology known in the art, a drill being inserted at an aniilc into the ground at an entrance hole 12 and being drilled horizontally along a distance appropriate for the cleaning and with respect to the equipment adapted to about 100 to 200 metres, before the drill is lifted out of the ground at an exit hole 14. Several such holes 10 are drilled parallel with each other in accordance with figure 2 to cover the ground area to be decontaminated in the other direction. The distance between the holes 10 in this other direction might be of the order of 1 to 3 metres, e.g. 2 metres, depending on the circumstances in the contaminated ground to be cleaned. According to the invention a chord 16 of an appropriate material, such as a plastic material, is inserted in the drilled holes, the chord 16 connecting a multitude of at appropriate intermediate intervals spaced sockets I K for a sorbe t. The sockets 18 consist of a material letting liquid pass into and out of the socket, such as a net material with meshes of a magnitude to retain sorbent particles in the socket 18. The distance between the sockets 18 on the chord 16 is a function of the type of sorbent and the conditions of the poisoned soil to be cleaned, the distance being such that the sorbent in two neighbouring sockets 18 arc operating on the intermediate ground surface both in the longitudinal and the transverse direction. If it is necessary to reinforce the hole 10 and to facilitate the insertion of the chord 16, the hole might be lined with a slotted or perforated, here not shown hose. Instead of the embodiment here shown it might be envisaged that the chord 16 itself consists of a hose with fine meshes containing the sorbent, eventually with compressed portions in the hose in appropriate spaces to keep the sorbent equally distributed in the hose. In this case the socket 18 might be abolished. Zeolites with a chrystallinc structure might be used as a sorbent provided in the socket 18 providing a large absorption capacity and thus absorbing large quantities of different kinds of materials, such as heavy metals and other harmful substances. The absorption is achieved in that the soil is moist and in most cases the moisture of the soil itself will be sufficient for the desired effect, but water might be added if this is desirable so that the ground is moistened at the drilled holes. When the chords of the sorbent sockets have been lying under the ground for a sufficiently long period to achieve the desired cleaning or decontamination of the soil, the chord is retracted out of the drilled hole and the employed sorbent can be regenerated for a new application for a decontamination of further areas. From the description above it is evident that a very simple and inexpensive method has been provided to decontaminate large areas of poisoned soils on the spot without any handling of the soil itself being necessary. Obviously, the embodiment shown above represents merely an example of the implementation of the invention and changes might be made without leaving the scope of the invention. Thus, the sockets 18 can have another form than that already shown, e.g. having a spherical or longitudinal shape arranged with larger or smaller intermediate spaces or consisting, as stated above, of a single hose, eventually compressed in equal intermediate spaces. The sorbent might also be another one than zeolite, depending on the type of contamination to be removed from the ground.

Claims: Claims 1. A method for decontaminating soil on the spot from harmful substances, characterized in that one or several horizontally drilled holes (10) arc provided, which at least at one end arc debouching into the ground surface, that into the hole a chord (16) is inserted, in which substances are stored consisting of reactive sorbents and in that said chord (16) remains under the ground during a sufficiently long period for a desired decontamination of the soil. 2. A method according to claim 1 , characterized in that a chord is used in form of a number of interlinked sockets (18) for the sorbent. 3. A method according to claim 1 or 2, characterized in that a chord (16) is used in form of a hose in a nctlike material for retaining the sorbent. 4. A method according to claim 1, 2 or 3, characterized in that the hole (10) is lined with a slotted or perforated hose, in which the chord with the sockets is inserted. 5. A method according to claim 1, 2 or 4, characterized in that the sockets (18) are designed in a netlike material to retain the sorbent material. 6. A method according to anyone of the claims 1 to ϋ, characterized in that as a sorbent is used a molecule screen, such as zeolites. 7. A method according to anyone of the claims 1 to 6, characterized in that the ground is moistened at the drilled holes. 8. A method according to anyone of the claims 1 to 7, characterized in that the sorbent after said period is regenerated for a further application. 9. A device for performing the method according to anyone of the claims 1 to 8, for decontaminating soil on the spot from harmful substances, characterized in a chord (16) in form of a hose or with intermediately spaced sockets (18) for a sorbent, the chord being arranged into one or several holes drilled into the ground to be decontaminated. 10. A device according to claim 9, characterized in that the chord consists of a rope (16) of plastics or a similar suitable material, with which the sockets (18) are connected in a desired intermediate space. 11. A device according to claim 9 or 10 , characterized in that the chord (16) is arranged in a slotted or perforated hose. 12. A device according to anyone of the claims 9 to 1 1 , characterized in that the hose or the sockets arc made of a nctlike material with meshes smaller than the sorbent particles.

Inventors: SCHWALBE PONTUS, SCHWALBE, PONTUS
Applicants: GLOBE WATER AB, SCHWALBE PONTUS, SCHWALBE, PONTUS
Application year: 1998
Main classification: B09C1
IPC codes: B09C1