Search

CA-3110438-C - DEVICE FOR THE REMOVAL OF SLUDGE AND/OR SAND FROM THE BOTTOM OF A WETLAND

CA3110438CCA 3110438 CCA3110438 CCA 3110438CCA-3110438-C

Abstract

Device for the in situ underwater removal of a layer of sludge and/or sand from the bottom of a wetland, the device containing: a diving bell (5) with an open bottom (7) and a lower free edge (10); means of driving the diving bell with its lower edge to a desired depth into the layer of sludge to be removed; a dredge pump ( 11) installed in the space of the diving bell and provided with an inlet (13) for pumping up the sludge and/or an outlet (15) to which a pipe (18) is connected for pumping the pumped up sludge and/or sand to a collector (17); a compressor (21) for pumping gas under pressure into the space of the diving bell during dredging, wherein the diving bell is also provided with a gas outlet (25) for the compressed gas, which gas outlet is adjustable in height in the diving bell because the outlet is attached to a float (27) that can float on the sludge.

Inventors

  • Boudewijn Gabriel VAN ROMPAY

Assignees

  • Boudewijn Gabriel VAN ROMPAY

Dates

Publication Date
20260505
Application Date
20190912
Priority Date
20180914

Claims (19)

  1. 15 Claims 1. A device for the in situ underwater removal of a layer of sludge and/or sand from the bottom of a wetland, the device containing: 5 10 15 20 25 30 a diving bell with an open bottom and a lower free edge; means of driving the diving bell with the lower free edge to a desired depth into the layer of sludge to be removed; a dredge pump installed in a space of the diving bell and provided with (i) an inlet for pumping up the sludge or (ii) an outlet to which a pipe is connected for pumping the pumped up sludge and/or sand to a collector or (iii) the inlet and the outlet; a compressor for pumping gas under pressure into the space of the diving bell during dredging, wherein the diving bell is also provided with a gas outlet for the compressed gas, which gas outlet is adjustable in height in the diving bell because the outlet is attached to a float that can float on the sludge.
  2. 2. The device according to claim 1, wherein the gas outlet is formed by an open end of a pipe which releases via an opening at a top of the diving bell into the environment.
  3. 3. The device according to claim 2, wherein the pipe discharges above a water level of the wetland.
  4. 4. The device according to any one of claims 1 to 3, wherein the outlet is located with an upper edge at a small height above the float. 16 5.
  5. 5 10 15 20 25 30 The device according to any one of claims 1 to 4, wherein the float with the gas outlet mounted thereon, is suspended in the diving bell by means of a chain, the length of which is such that when the diving bell is taken out of the water, the float with its underside is substantially at the level of the lower edge of the diving bell.
  6. 6. The device according to any one of claims 1 to 5, wherein the float is such that the float floats on the sludge, but does not have sufficient buoyancy to allow the compressed gas outlet to float on the water, together with the weight of the pipe and the outlet.
  7. 7. The device according to claim 6, wherein the float is formed by a sufficiently dimensioned sheet to bear the weight of the pipe on the sheet on the sludge.
  8. 8. The device according to any one of claims 1 to 7, wherein the pipe is formed by a rigid metal tube which rests and is attached to the float with one end and with an other end releases via a flexible coupling at the top of the diving bell into an environment of the diving bell.
  9. 9. The device according to any one of claims 1 to 8, wherein the dredge pump is attached to a fixed place in the diving bell with the inlet on a level of the lower free edge of the diving bell. 17 5 10 15 20 25 30
  10. 10. The device according to any one of claims 1 to 9, wherein a maximum pressure to which the compressor is set is higher than the pressure of a water column with a height equal to the difference in level between the water surface of the wetland and the lower free edge of the diving bell.
  11. 11. The device according to any one of claims 1 to 10, wherein the lower free edge of the diving bell is made as a blade.
  12. 12. The device according to any one of claims 1 to 11, wherein near the lower edge of the diving bell the device is provided with a water jet that is fed by a jet pump that sprays water into the sludge inside.
  13. 13. The device according to claim 12, wherein the jet pump is mounted on the outside of the diving bell and via pipes is connected with passages in a wall of the diving bell, which pipes discharge in the diving bell in a direction perpendicular to said wall.
  14. 14. The device according to any one of claims 1 to 13, wherein the means to drive the diving bell in the sludge are formed by a hydraulic crane with a hydraulic unit that supplies hydraulic power to drive the dredge pump and, when dependent on claim 12 or 13, the jet pump.
  15. 15. The device according to claim 14, wherein the hydraulic crane is set up on a work boat or a pontoon, together with the compressor. 18
  16. 16. The device according to any one of claims 1 to 15, wherein the device is provided with means to assess the depth of the diving bell in the layer of sludge. 5 10 15
  17. 17. The device according to claim 15, wherein the means to assess the depth of the diving bell in the sludge are formed by a depth scale on a sidewall of the bell and a camera.
  18. 18. The device according to any one of claims 1 to 17, wherein the device is provided with means to assess a thickness of the layer of sludge.
  19. 19. A use of the device as defined in any one of claims 1 to 18, wherein the device is used for the removal of a layer of sludge and/or sand from the bottom of a wetland.

Description

1 Device for the removal of sludge and/or sand from the bottom of a w;Jtland. 5 This invention relates to a method for the removal of sludge and/or sand from the bottom of a wetland. The invention applies both to the removal of sludge and to the removal of a"' underlyin9 sand layer up to a certa-1_n 10 depth. For the sake of simplicity, the te:crn sl-,Jdg-e is used below, which also refers to the underlying sand layers. More specif tca l ly, the method relates to the in situ pumping UD of polluted sludge underwater with minimal turbulence. It j_ s genera_;_• l y k.. _nown t-'n a-t- the sludge of maritime waterways may be contarntnated with toxic chem"lcals and heavy metals from accidental or illegal discharqes or from seepar:.re from .industrial sites, such as, for example! pollu lion by toxtc substances that are often present on the hull of a ship repel the 9rowth of marine organisms. These harmful substances remain present in the sludge of port areas and mari ti:me waterways. These pollutions a.round pGrt detrimental effect on the local indiqenous marine organ-isms. However r a problem i ~:, that current dredqinq techn_-Lques to remove sludge from the bottom of a wetland are often relatively inefficient in the sense that they create a lot of 30 turbulence, causing sludge churn as well as turbidity or 2 muddiness in the water. The water content in the sludge is increased by the churning during dredging. This is not interesting because to clean the 5 pumped up sluetg·er the rnoisture content has to be complet;Jly or partially removed. An increased moisture content therefore makes the dredging process relatively more expensive and the cleaning of the pumped up sludge more time-consuming. HJ Another disadvantage of the turbuJ.ence caused is tha.t the churned polluted sludge spreads out over the wetland by resuspension of the sludge and possibly rnixe~:; wi U1 unpol.l uted s.ludger while in fact the dredging and removal of the sludge should remain in situ as much as possible. In additionr t-.he prec.1' .p1. t- at i' on of the resuspended sludge completely or even. completely destroys soil ()[98.Tl 1.Sffi.S., 20 One consequence of the risk that a lot of turbulence :Ls created using traditional sludge removal techniques, is that sucn pol.luted water bodies are left untouched by the authorities to avoid. the risk of further dispeDsa1 through churn and inefficient removal. Th.1.s i.mplies that polluted port areas are not deepened or expanded any further, which means that these areas with potentially high economic va.lue remain unused. 30 In BE 1.018.005 and BE 1.021.095 of the same inventorr 3 techniques are already known for in. situ dredq_1_ngf using a diving bell which is pushed into the sludge to be removed and from 1::hich the enclosed sludqe is pumped away 0 S The purpose of the present invent.ion is to further improve these known techniques using a diving bell. To this end, the present invention relates to a device for the underwater in situ removal of sludge and/or sand from the 10 bottom of a wetland, the device containing: a diving bell with an open bottom and a lower free edge; - means of floating the diving bell with its lower edge to a desired depth into the la_yer of sludqe and/or ~sand to be removed; 1-':) - a dredge pump installed in the ~:;pace of the diving bell and provided w_U~h an inlet for pumping up the sludge and/or an outlet to which a pipe is connected fer purnpinq the pumped up sludge and/ or sand to a C(;_U_ector; - a compressor for pumping gas under pressure into the spa.ce 20 of the diving bell during dredging, whereby the diving bell is also provided <;,1ith a gas outlet for the compressed gasf which 9as outlet in the divinq bell is adjustable in height because the outlet is attached to a float that can float on the sludge. This movable outlet of the compressed gas will allow the air above the slu_dge or sand to escape freely when the diving bell is driven :Lnto the sludge or sand, so that the diving bell ca_n be filj_ed with sludge or sand as much as possible 30 without the water being driven out. 4 The outlet. will always be abDve the sludge or sand to be removed and the float, together with the movable outlet and the st,pply of the compressed gas, ensure that the water level 5 and the pressure above the water in the bell are self- Indeed{ the a J.r in the div inq bel 1 wL. l be able to escape through the out.1.et, and the water level will stabilise at the 10 level of the upper edqe of the outlet. As the LLoat and therefore also the outlet mounted on it fol.low the level of the sJ.udger the level of. the water will also follow the level of the sludge or sand and therefore the 15 level of the sl.udge or sand and the level of the water will decrease l:ogether as more sludge or sand is pumped away, Because both levels drop at the same time, there is no flow of water through the sludge to the out.si.def .so that the pollution cannot escape to the OLttside andf :Ln other wonJs, d.1.i :c