GB2179645A - Waste management system - Google Patents

Abstract

The rapid growth of urban areas provides enormous waste management problems for the responsible municipal authorities. Waste is transported to a processing plant where it is mixed with water and mechanically broken down to form a pumpable waste/water slurry. The slurry is pumped on board a ship either from a dockside processing plant directly on board or from an inland plant by a suitable pipeline. When a ship has a full load it sails to a deep ocean site where slurry in pumpable form is passed down a flexible pipe and extruded onto the seabed. It may be advantageous to provide a water-jetting pipe in conjunction with the slurry extrusion pipe so that a water jet can be used to cut a shallow trench for the slurry.

Description

SPECIFICATION Waste management system The present invention relates to a waste managementsystem, and in particular a system forthe processing and disposal of waste, e.g. urban and nontoxic industrial waste.

The rapid growth of urban areas provides enor mous waste management problems for the responsible municipal authorities. Great expense may be involved intransporting largevolumesofe.g.dom- estic refuse away from cities to suitable land-fill sites or incinerators. Conventional waste tips and incinerators have the attendant disadvantages of un- sightliness, odour, vermin, fumes etc.

According to the invention waste is transported, e.g. by road or rail, to a processing plant where the waste is mixed with water and mechanically broken down to form a waste/water slurry. Sufficient water is used to provide a pumpable slurry. The slurry is pumped on board a ship, and carried away for disposal as described below. The slurry can be pumped from a dockside processing plant directly on board or it can be pumped from an inland plant by a suitable pipeline with relay pumping stations therealong. The slurrymay be pumped directlyaboard a ship, orit may first be pumped into a temporary buffer storage tank. Such a tank could for example be on land close to a dockside or could equally be anothership.

On board ship the waste/water slurry may advantageously be partially dewatered to reduce its volume. When a ship has a full load it sails to a deep ocean site, e.g. a site well away from land masses and having a water depth of about 1000 to 1500 metres. Slurry in pumpableform (i.e. rewatered if necessary) is passed down a flexible pipe reaching to the seabed and extruded onto the seabed. It may be advantageous to provide a water-jetting pipe in conjunction with the slurry extrusion pipe so that a water jet can be used to cut a shallowtrench fortheslurry.

It is commercially desirable to use a number of ships operating a shuttle service between the load and off-loading sites.

Urban and non-toxic industrial waste comprises mainly biodegradable paper and foodstuffs, plastics, glass and metal cans etc. Metal objects can be removed from the raw waste in a pretreatment step before slurrying. Crushing and grinding apparatus is commercially available which can be used to pulp plastics and glass. Large objects can be removed from the waste and/or slurry by sieving.

If desirable, binding agents e.g. latex polymers and the like may be added to the slurry before extruding it onto the seabed. This tends to stabilise the slurry and allow time for sand, silt etc. to cover the extruded slurry. Over a period of time the biodegradable con tentoftheslurrywill decay away leaving only an inert residue including finely divided plastics and glass.

In a preferred embodiment of the invention conventional refuse trucks bring waste to a plant located close to a dock. Metal objects are first removed from the waste and it is then mechanically broken down and water added. A slurry is formed and pumped into buffer storage tanks on a ship mooredatthe dockside. On this ship the slurry is partially dewatered and the extracted water is recirculated to the plant forfurther slurrying. Two or more ships op- erate a shuttle service, plying back and forth between the storage ship and a deep ocean site. Each ship has long retractable flexible pipes for water-jetting and for slurry extrusion.It is particularly advantageous if the moored storage ship also has equipmentfor water-jetting and slurry extrusion so that it can replace a shuttle ship in the event that one needs to be taken out of service.

1. Awaste management system comprising: 1) a plant for receiving waste (e.g. urban and nontoxic industrial waste) and for forming therefrom a pumpable waste/water slurry.

2) a pipelineforcarrying pumpedslurrvaway from said plant, and 3) a ship for receiving said pumped slurry, which ship is provided with a retractable length of flexible pipe from which slurry is extrudable at a deep ocean site on to the seabed.

2. A method for processing and disposing of waste (e.g. urban and non-toxic industrial waste) which comprises mixing waste with water and mechanically breaking the mixture down to form a pum pable waste/water slurry, pumping the slurry by pipeline to a ship, sailing the shfp to a deep water site, extending a flexible pipe from the ship to the seabed, pumping the slurry from the ship along the pipe and extruding the slurry on to the seabed.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (2)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Waste management system The present invention relates to a waste managementsystem, and in particular a system forthe processing and disposal of waste, e.g. urban and nontoxic industrial waste. The rapid growth of urban areas provides enor mous waste management problems for the responsible municipal authorities. Great expense may be involved intransporting largevolumesofe.g.dom- estic refuse away from cities to suitable land-fill sites or incinerators. Conventional waste tips and incinerators have the attendant disadvantages of un- sightliness, odour, vermin, fumes etc. According to the invention waste is transported, e.g. by road or rail, to a processing plant where the waste is mixed with water and mechanically broken down to form a waste/water slurry. Sufficient water is used to provide a pumpable slurry. The slurry is pumped on board a ship, and carried away for disposal as described below. The slurry can be pumped from a dockside processing plant directly on board or it can be pumped from an inland plant by a suitable pipeline with relay pumping stations therealong. The slurrymay be pumped directlyaboard a ship, orit may first be pumped into a temporary buffer storage tank. Such a tank could for example be on land close to a dockside or could equally be anothership. On board ship the waste/water slurry may advantageously be partially dewatered to reduce its volume. When a ship has a full load it sails to a deep ocean site, e.g. a site well away from land masses and having a water depth of about 1000 to 1500 metres. Slurry in pumpableform (i.e. rewatered if necessary) is passed down a flexible pipe reaching to the seabed and extruded onto the seabed. It may be advantageous to provide a water-jetting pipe in conjunction with the slurry extrusion pipe so that a water jet can be used to cut a shallowtrench fortheslurry. It is commercially desirable to use a number of ships operating a shuttle service between the load and off-loading sites. Urban and non-toxic industrial waste comprises mainly biodegradable paper and foodstuffs, plastics, glass and metal cans etc. Metal objects can be removed from the raw waste in a pretreatment step before slurrying. Crushing and grinding apparatus is commercially available which can be used to pulp plastics and glass. Large objects can be removed from the waste and/or slurry by sieving. If desirable, binding agents e.g. latex polymers and the like may be added to the slurry before extruding it onto the seabed. This tends to stabilise the slurry and allow time for sand, silt etc. to cover the extruded slurry. Over a period of time the biodegradable con tentoftheslurrywill decay away leaving only an inert residue including finely divided plastics and glass. In a preferred embodiment of the invention conventional refuse trucks bring waste to a plant located close to a dock. Metal objects are first removed from the waste and it is then mechanically broken down and water added. A slurry is formed and pumped into buffer storage tanks on a ship mooredatthe dockside. On this ship the slurry is partially dewatered and the extracted water is recirculated to the plant forfurther slurrying. Two or more ships op- erate a shuttle service, plying back and forth between the storage ship and a deep ocean site. Each ship has long retractable flexible pipes for water-jetting and for slurry extrusion.It is particularly advantageous if the moored storage ship also has equipmentfor water-jetting and slurry extrusion so that it can replace a shuttle ship in the event that one needs to be taken out of service. CLAIMS

1. Awaste management system comprising: 1) a plant for receiving waste (e.g. urban and nontoxic industrial waste) and for forming therefrom a pumpable waste/water slurry.

2. A method for processing and disposing of waste (e.g. urban and non-toxic industrial waste) which comprises mixing waste with water and mechanically breaking the mixture down to form a pum pable waste/water slurry, pumping the slurry by pipeline to a ship, sailing the shfp to a deep water site, extending a flexible pipe from the ship to the seabed, pumping the slurry from the ship along the pipe and extruding the slurry on to the seabed.

2) a pipelineforcarrying pumpedslurrvaway from said plant, and 3) a ship for receiving said pumped slurry, which ship is provided with a retractable length of flexible pipe from which slurry is extrudable at a deep ocean site on to the seabed.