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Title:
WASTE STORAGE LANDFILL CELL
Document Type and Number:
WIPO Patent Application WO/2016/028136
Kind Code:
A1
Abstract:
The present invention relates to a waste storage landfill cell (1) comprising of an earthen containment space (20) formed from an excavated pit for waste storage; a cover system (10) fitted over the earthen containment space; and a liner system (30) lining the earthen containment space. The liner system (30) and the cover system (10) of this landfill cell includes hydrophobic nanofibres overlapping each other in a random manner to form a hydrophobic nanofibres membrane (17,36) that is impermeable only to liquids.

Inventors:
ROSALAM SARBATLY (Jalan UMS Kota Kinabalu, Sabah, 88400, MY)
Application Number:
MY2014/000221
Publication Date:
February 25, 2016
Filing Date:
August 22, 2014
Export Citation:
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Assignee:
UNIVERSITI MALAYSIA SABAH (Jalan UMS, Kota Kinabalu, Sabah, 88400, MY)
International Classes:
B09B1/00; E02D31/00
Foreign References:
US8585322B22013-11-19
US7309188B22007-12-18
CN202390861U2012-08-22
Attorney, Agent or Firm:
H. A. RASHID, Ahmad Fadzlee (Ipvolusi Sdn Bhd, A-3-3A Centrio Pantai Hillpark,No., Jalan Pantai Murni Kuala Lumpur, 59200, MY)
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Claims:
CLAIMS

1. A waste storage landfill cell (1), comprising:

an earthen containment space (20) formed from an excavated pit for waste storage, and

a liner system (30) for lining the earthen containment space (20), wherein the liner system (30) is characterized in that it includes a layer of hydrophobic nanofibres membrane (17,36) that is impermeable only to liquids.

The waste storage landfill cell (1) as claimed in claim 1 , wherein the liner system (30), comprises:

a geonet (31) to collect leachate produced from waste; a geotextile fabric (32) layered beneath the geonet (31) to filter solid particles from leachate and to prevent clogging of perforated pipes

(34);

a gravel bed (33) embedding a set of perforated pipes (34) and layered beneath the geotextile fabric (32) to filter solid particles from leachate and to prevent clogging of perforated pipes (34); a set of perforated pipes (34) embedded in the gravel bed (32) to channel leachate out of the waste storage landfill cell (1); a geomembrane liner (35) layered beneath the gravel bed (33) to prevent the escape of leachate and landfill gases from the waste storage landfill cell (1); and

a hydrophobic nanofibres membrane (36) layered beneath the geomembrane liner (35) to prevent leachate from escaping the waste storage landfill cell (1) and to prevent the geomembrane liner (35) from puncturing and leaking.

3. The waste storage landfill cell (1) as claimed in claim 1 , wherein the earthen containment space (20) is enclosed by a cover system (10), and wherein the cover system (10), comprises:

a vegetation layer (11) exposed to the atmosphere and planted into a top soil (12) to prevent the erosion of underlying soils; a layer of top soil (12) beneath the vegetation layer (11) to retain moisture and supply nutrients to the vegetation layer (11); a layer of cover soil (13) beneath the top soil (12) to retain moisture for the growth of the vegetation layer (11);

a geotextile fabric (14) layered beneath the cover soil (13) to separate between the solid particles and liquid and to prevent a geonet layer (15) beneath it from clogging;

a geonet (15) layered beneath the geotextile fabric (14) to drain excess precipitation from its above layers resulting from surface water and rain water;

a geomembrane liner (16) layered beneath the geonet (15) to prevent infiltration of water through the waste storage landfill cell (1) and prevent the escape of landfill gases from the waste storage landfill cell

(1);

a hydrophobic nanofibres membrane (17) layered beneath the geomembrane liner (12) to prevent infiltration of water into the waste storage landfill cell (1); and

a layer of soil (18) layered beneath the hydrophobic nanofibres membrane (17) covering the retained waste materials.

A method of fabricating hydrophobic nanofibres membrane (17,36), is characterized by the steps of:

a) melting of polymer;

b) spraying of the melted polymer to form hydrophobic polymeric nanofibres; and

c) compacting the hydrophobic polymeric nanofibres onto a wire mesh to form a hydrophobic nanofibre membrane (17,36).

The method as claimed in claim 4, wherein said polymer is selected from the group consisting of rubber, polyethylene, polypropylene, polyvinylidene fluoride and polytetrafluoroethylene or a mixture thereof.

The method as claimed in claim 4, wherein the diameter of said hydrophobic polymeric nanofibres is between 300 to 1000 nm.

The method as claimed in claim 4, wherein the step of compacting the hydrophobic polymeric nanofibres onto a wire mesh to form a hydrophobic nanofibres membrane (17,36) is done by either: roling, calendering, pressing or spraying.

The method as claimed in claim 4, wherein the thickness of said hydrophobic nanofibres membrane (17,36) is not less than 5 mm.

Description:
WASTE STORAGE LANDFILL CELL

FIELD OF INVENTION

The present invention relates to a waste storage landfill cell. More particularly, the present invention relates to a hydrophobic nanofibre-based waste storage landfill cell.

BACKGROUND OF THE INVENTION

A landfill site is a site for burying waste material. For an un-engineered landfill, rain falling on the top of the landfill can generate a significant amount of leachate as the rainwater is passing through the waste materials. Leachate is a solution containing dissolved liquids and suspended solids which are derived from organic and inorganic compounds. The volume of leachate increases when biodegradable decomposition of the waste materials takes place. Leachate may enter natural water supplies by gravitational force, carrying with it environmentally harmful substances.

The designs of landfills in recent years proposes to prevent leachate from polluting the underlying groundwater sources by utilizing clay-based liners with low permeability to liquid. Clay-based liner comprises of barrier layers for separating the landfill from the environment. Leachate is retained in the liner before being directed through a series of pipes to a storage tank for further treatment. Compacted clay liners (CCLs) and geosynthetic clay liners (GCLs) are clay-based liners commonly used to construct waste landfills. The thickness of the CCLs may be varied between 0.3 and 3 m while the GCLs consists of a thin clay layer with several millimetres (4-6 mm). However, the use of clay-based liners and covers have a few drawbacks as follows:(1 ) desiccation of the clay resulting in cracks and could increase the fluxes of rain water and contaminants; (2) GCLs may be punctured during or after installation because they are relatively thin; (3) installation is highly labour intensive because the clay-based liners are heavy; (4) installation could not be conducted during damp conditions because the clay absorbs water to become soft and difficult to handle; and (5) total cost of materials and installation is expensive.

Example of waste landfill utilizing clay-based liners can be found in United States Patent No. 4483641. The prior art discloses an in ground reservoir with clay based liner and cover. The prior art proposes a method of leachate abatement from within the landfill by inducing air flow through a ventilation layer disposed between the cover and the waste. The prior art utilizes natural convection flow of ambient air through the ventilation layer out the central conduit to exhaust to the atmosphere. Thus, it can be perceived that the prior art has a drawback in that gasses and odours from the decomposition process of contained waste materials will be diffused into the environment. Furthermore, the United States Patent No. 4483641 do not suggest a method of improving the durability, ease of instalment and weight reduction of the clay-based liners.

Therefore there is a need for a waste storage system that addresses the abovementioned limitations of the existing waste storage system.

SUMMARY OF INVENTION

In accordance with the present invention, there is provided a waste storage landfill cell (1), comprising an earthen containment space (20) formed from an excavated pit for waste storage, and a liner system (30) for lining the earthen containment space (20), wherein the liner system (30) is characterized in that it includes a layer of hydrophobic nanofibres membrane (17,36) that is impermeable only to liquids.

Preferably, the liner system (30) comprises a geonet (31) to collect leachate produced from waste, a geotextile fabric (32) layered beneath the geonet (31) to filter solid particles from leachate and to prevent clogging of perforated pipes (34), a gravel bed (33) embedding a set of perforated pipes (34) and layered beneath the geotextile fabric (32) to filter solid particles from leachate and to prevent clogging of perforated pipes (34), a set of perforated pipes (34) embedded in the gravel bed (32) to channel leachate out of the waste storage landfill cell (1), a geomembrane liner (35) layered beneath the gravel bed (33) to prevent the escape of leachate and landfill gases from the waste storage landfill cell (1), and a hydrophobic nanofibres membrane (36) layered beneath the geomembrane liner (35) to prevent leachate from escaping the waste storage landfill cell (1) and to prevent the geomembrane liner (35) from puncturing and leaking. Preferably, the earthen containment space (20) is enclosed by a cover system (10), wherein the cover system (10) comprises of a vegetation layer (11) exposed to the atmosphere and planted into a top soil (12) to prevent the erosion of underlying soils, a layer of top soil (12) beneath the vegetation layer (11) to retain moisture and supply nutrients to the vegetation layer (11), a layer of cover soil (13) beneath the top soil (12) to retain moisture for the growth of the vegetation layer (11), a geotextile fabric (14) layered beneath the cover soil (13) to separate between the solid particles and liquid and to prevent a geonet layer (15) beneath it from clogging, a geonet (15) layered beneath the geotextile fabric (14) to drain excess precipitation from its above layers resulting from surface water and rain water, a geomembrane liner (16) layered beneath the geonet (15) to prevent infiltration of water through the waste storage landfill cell (1) and prevent the escape of landfill gases from the waste storage landfill cell (1), a hydrophobic nanofibres membrane (17) layered beneath the geomembrane liner (12) to prevent infiltration of water into the waste storage landfill cell (1), and a layer of soil (18) layered beneath the hydrophobic nanofibres membrane (17) covering the retained waste materials.

In accordance with the present invention, there is provided a method of fabricating hydrophobic nanofibres membrane (17,36), characterized by the steps of melting of polymer; spraying of the melted polymer to form hydrophobic polymeric nanofibres; and compacting the hydrophobic polymeric nanofibres to form a hydrophobic nanofibres membrane (17,36).

Preferably, the polymer is selected from the group consisting of rubber, polyethylene, polypropylene, polyvinylidene fluoride and polytetrafluoroethylene or a mixture thereof.

Preferably, the diameter of the hydrophobic polymeric nanofibres is between 300 to 1000 nm.

Preferably, the step of compacting the hydrophobic polymeric nanofibres onto a wire mesh to form a hydrophobic nanofibres membrane (17,36) is done by either; rolling, calendering, pressing or spraying. Preferably, the thickness of the hydrophobic nanofibres membrane (17,36) is not less than 5 mm.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1 is a schematic cross-sectional view of a waste storage landfill cell (1) in accordance with an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a cover system (10) of the waste storage landfill cell (1) of FIG. 1. FIG. 3 is a schematic cross-sectional view of a liner system (30) of the waste storage landfill cell (1) of FIG. 1.

DESCRIPTION OF THE PREFFERED EMBODIMENT

A preferred embodiment of the present invention will be described herein below with reference to the accompanying drawings. In the following description, well known functions or constructions are not described in detail since they would obscure the description with unnecessary detail.

Referring to FIG. 1 , there is shown a waste storage landfill cell (1) in accordance with an embodiment of the present invention. The waste storage landfill cell (1) comprises an earthen containment space (20), a cover system (10) and a liner system (30). The earthen containment space (20) is formed from an excavated pit and lined using a liner system (30). The liner system (30) is used to contain waste material from leaching into the environment (40). The earthen containment space (20) filled with waste material is then closed, or capped, by a cover system (10).

Referring now to FIG. 2, the cover system (10) of the waste storage landfill cell (1) comprises of various layers. A vegetation layer (11) makes up the outermost layer of the cover system (10) and is exposed to the atmosphere. The vegetation layer (11) is planted with plants to prevent the erosion of underlying soils. A layer of top soil (12) is layered beneath the vegetation layer (11) to provide support for the growth of the plants by keeping moisture and supplying nutrients. A cover soil (13) is layered beneath the top soil (12) to protect the cover system (10) and also to retain moisture for the growth of the vegetation layer (11). A geotextile fabric (14) is placed beneath the cover soil (13) and above the geonet (15) as a separator between the solid particles and liquid. The geotextile fabric (14) is also required to prevent the geonet (15) beneath it from clogging due to the solid particles. The geonet (15) functions as a drainage layer to drain excess precipitation from its above layers resulted from surface water as well as rain water. A geomembrane liner (16) is layered beneath the geonet (15). The geomembrane liner (16), preferably of high- density-polyethylene (HDPE) plastic, helps to prevent infiltration of water through the waste storage landfill cell (1). Furthermore, the impermeable geomembrane liner (16) helps to prevent the escape of landfill gases due to biodegradation process of waste material. A hydrophobic nanofibres membrane (17) is disposed beneath the geomembrane liner (16). The main function of the hydrophobic nanofibres membrane (17) is to prevent excess precipitation such as surface water and rain water from entering the landfill and forming leachate using its water repelling nature. A layer of soil (18) is layered beneath the hydrophobic nanofibres membrane (17) to cover contained waste material. The layer of soil (18) also helps to keep the waste material from scattering and minimize odours.

Referring now to FIG. 3, waste material (20) is contained in an earthen containment space formed by a liner system (30). Leachate produced from the waste material (20) is collected by a geonet (31). A geotextile fabric (32) is layered beneath the geonet (31) to separate leachate from any solid particles and prevent clogging of perforated pipes (34) beneath it. A gravel bed (33) is layered beneath the geotextile fabric (32). Embedded within the gravel bed (33) is a set of perforated pipes (34) to direct leachate produced from biodegradable decomposition process of retained waste material towards a storage tank for further treatment. The leachate is drained by a gravitational action to the perforated pipes (34). The perforated pipes (34) provide a path for the leachate to reach treatment facilities (not shown). A geomembrane liner (35) is layered beneath the gravel bed (33). The geomembrane liner (35) is impermeable to liquid and gases; so as to prevent the leachate and gases from diffusing and entering the environment (40). A layer of hydrophobic nanofibres membrane (36) placed directly below the geomembrane liner (35), to form an additional barrier to prevent the leachate from penetrating into the environment (40). Besides that, the hydrophobic nanofibres membrane (36) also functions as a protective layer or a cushion layer to prevent geomembrane liner (35) from puncturing and leaking.

On the other hand, the steps involved in the fabrication of hydrophobic nanofibres membrane (17,36) of the waste storage landfill cell (1) is as described as the following: Initially, a polymer is melted. The polymer is selected from the group consisting of rubber, polyethylene, polypropylene, polyvinylidene fluoride and polytetrafluoroethylene or a mixture thereof.

Thereon, the melted polymer is sprayed to form hydrophobic polymeric nanofibres. Preferably, the diameter of hydrophobic polymeric nanofibres ranges between 300 to 1000 nm.

Finally, the hydrophobic polymeric nanofibres is compacted to form a hydrophobic nanofibres membrane (17,36). A relatively high mass of the hydrophobic polymeric nanofibres is compacted onto a wiremass such that the hydrophobic polymeric nanofibres overlaps each other in a completely random manner by either roling, calendering, pressing or spraying. Preferably, the thickness of said hydrophobic nanofibres membrane (17,36) is not less than 5 mm. While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specifications are words of description rather than limitation and various changes may be made without departing from the scope of the invention.