GB2350801A - Sewage compactor with washing means - Google Patents

Abstract

A sewage compactor comprises a fluid transmission member 502 having a surface 209 suitable for recieving a material to be compacted, the surface having fluid outletting means 504 for outletting fluid to the material. The device may further comprise a chassis, at least one compartment and a motor. The fluid outletting means 504 are preferably made up of a plurality of apertures with nozzle units arranged to transmit fluid from an internal space of the central shaft of the fluid transmission member 502. In operation the motor preferably rotates the transmission member 502 which is preferably in the form of an Archimedean screw. The motor is preferably connected to the fluid transmission member by a mounting shaft which may have a hollow core communicating with the central space of the transmission member. The internal space of either the transmission member or the mounting shaft may be connected to a fluid supply 601 by a rotary union coupling 602.

Description

2350801 SEWAGE COMPACTOR

Field of the Invention

The present invention relates to devices for the compaction and washing of 5 solids and semi-solids, and particularly, although not exclusively, to a compactor unit for sewage waste solid compaction and washing.

Background to the Invention

In order to process raw sewage, the first stage is the removal of large waste 10 solids from the sewage by coarse and fine screening. These waste solids removed are compacted, dried and often disposed of at landfill sites.

It is known in the prior art that on entering a sewage treatment plant, the sewage is screened to remove large solids and particulate matter. The remaining effluent is further treated to remove smaller particulate matter by various filtration steps. It is further treated to lower the microbial content such that clean water can be returned to the rivers. At the initial screening stage, it is presently known in the prior art to use perforated screens preventing particles larger than 6mm in diameter from progressing. Other types of screen commonly employed at an initial screening stage include bar screens. These solid particles build up on such perforated screens, bar screens etc and are collected for instance by using a moveable screen progressing around a circuit such that as the screen is blocked with particulate matter, the screen can be rotated and the solid matter deposited in a suitable container. This screened matter constitutes solid waste which must be disposed of.

It is known in the prior art to dispose of such waste at landfill sites and in view of the costs imposed such as through landfill taxes, it is often of benefit to the water authority or company concerned to make the solid waste more compact, decreasing the volume of waste, such that the cost for disposing of solid waste at landfill becomes more economical. To this end, it is known in the prior art to use sewage compactors commonly consisting of a chamber housing an archimedes' screw used in operation to drive the solid waste into a second smaller chamber and result in compaction of the solid waste.

Further to the demand to decrease the cost of disposing of the solid waste at landfill sites, it is also of importance to remove any biological hazard that the solid waste may pose. One way of doing this is thought to be through washing the solid waste during the compaction stage. It is known in the prior art to use water sprayed onto the waste solid during compaction by an archimedes' screw, wherein the water is sprayed from an external site to the external surface of the waste solid. Such mechanisms provide for an improvement (ie a reduction) in the level of biological hazard of the waste solids. But the benefit to the water company is twofold in that washing waste solids during compaction will decrease the biological hazard they pose by washing away bacteria and other microbes and also decrease the volume of waste solids by breaking down the smaller particulate waste solids and faecal matter which are then removed with the water drained away from the compactor and returned to a stage in the sewage system before the initial screen. Such solids are hence re-screened and any solids which have been broken down to a particle size below 6 mm will be allowed to proceed through the system, whilst any solids still at the 6 mm particle size or larger will be returned to the compactor.

Although the system outlined for cleaning of waste solids during compaction provide an improvement in the volume of waste solids together with a limited decrease in biological hazard, these solids are not bound to be evenly cleaned. It is found that when a section of the resultant compacted solid is examined, the waste solids have not been cleaned evenly throughout, in particular the central region of a specimen of compacted waste solid is found to have not been cleaned at all.

The inventors have realized that by incorporating both an internal and external washing procedure on the material being compacted that a more fully washed product can be obtained. Such a product has a decreased Biological Oxygen Demand and hence biohazard and allows for an increased recycling of 5 small particulate matter washed away from the larger solids being compacted.

Summary of the Invention

Specific embodiments according to the present invention aim to improve the removal of liquids and small particulate matter, including faecal matter from large waste solids and other waste materials which are removed from an influent by one of many types of screens.

Specific embodiments according to the present invention aim to decrease the volume of waste materials removed from an influent by a suitable screen by compacting these waste materials to increase their density and decrease their volume.

One object of the specific embodiments of the present invention is to provide a decreased volume of waste materials removed from an influent using a suitable screen in order to decrease the volume of waste materials disposed of at landfill sites thus reducing the cost of disposing of the waste materials.

Another object of the specific embodiments of the present invention is to provide breakdown of loose matter being initially filtered by a suitable screen such that on re-screening a proportion of said loose organic matter will be able to progress beyond said suitable screen.

One object of the specific embodiments of the present invention is to provide an improved means of washing of waste materials removed from an influent by a suitable screen to decrease their Biological Oxygen Demand and thus decrease their potential biological hazard, thus making the compacted waste materials safer to dispose.

Specific methods according to the present invention aim to provide an improved washing of waste materials removed from an influent by a suitable screen.

Specific methods according to the present invention aim to decrease the Biological Oxygen Demand of waste materials removed from an influent by a suitable screen by a method of substantial washing of said waste materials during a compaction process.

Specific methods according to the present invention aim to break down loose solids removed from an influent by a suitable screen to become smaller particulate matter, which may be returned to an influent for re-screening.

Specific methods according to the present invention aim to compact waste materials removed from an influent by a suitable screen to decrease the volume and increase the density of the final compacted product whilst breaking down and removing loose material by incorporating a substantial washing step.

According to a first aspect of the present invention there is provided a device configurable for use in compacting a material, said device having a fluid transmission member wherein said fluid transmission member comprises a surface configurable for receiving said material and said surface comprising a means for outletting fluid to said received material.

Preferably said device comprises:

a chassis containing:

one or more compartments containing:

a fluid transmission member; a motor.

Suitably, said device where said fluid transmission member has a first end and a second end, said first end being attached to said motor, said second end laterally displaced from said first end, extending through one or more compartments.

Preferably, a device wherein said fluid transmission member contains one or a plurality of apertures configured to outlet said fluid to said received material.

Suitably, said fluid transmission member houses a nozzle unit in each aperture for outlet of fluid.

Preferably, a device where said fluid transmission member incorporates a central shaft with internal space for passage of fluid.

Preferably, said fluid transmission member through said compartments can be an archimedes' screw.

Suitably, said motor is operated in use to rotate said archimedes' screw.

Preferably, said motor is connected to said archimedes' screw by a separate mounting shaft.

Preferably, said mounting shaft has an internal space throughout its length so that when operable in use said internal space is continuous with an internal space within said archimedes' screw.

Preferably, a device wherein the internal space within either the mounting shaft or said fluid transmission member can be suitably connected to a fluid supply to provide fluid flow through the said internal space, exiting through said nozzles in said apertures.

Preferably, a device where said fluid supply is connected to said mounting shaft of said archimedes' screw by means of a rotary union.

Preferably, said chassis houses substantial piping suitable for outletting fluid to said material at any point in the compactor.

Preferably, said archimedes' screw is operable in use to move said material into an adjacent compartment for compaction of said material.

Preferably, a compartment for compaction has surface apertures to allow restricted outlet for material under compaction.

Preferably, said fluid transmission member is suitable for support in operation of water pressure of 7 bar.

Preferably, said fluid transmission member is operable as an archimedes' screw.

Suitably, said nozzles for use in outletting fluid from said fluid transmission member are capable of providing a combined water flow of 2 liters per second.

Preferably a compactor capable of compacting waste solids to 30% of their original volume.

Suitably, a compactor capable of decreasing waste solid Biological Oxygen 5 Demand by 80%.

Preferably a compactor washing a material under compaction wherein said fluid is water or water containing any suitable additives.

Preferably, a compactor compacting a material derived from sewage or a by 10 product of sewage.

According to a first specific method of the present invention, there is provided a method of processing a material prior to and during compaction, said method comprising the steps of.

receiving said material on the surface of a fluid transmission member; outletting fluid from a fluid transmission member to said material.

Preferably, a method of outletting fluid onto a fluid transmission member.

Suitably, a method of rotating a fluid transmission member wherein said fluid transmission member may be an archimedes' screw.

Preferably, a compactor, suitable for use in compacting waste materials removed from an influent containing raw sewage, said device comprising:

a chassis containing at least three compartments; a motor unit; a means of progressing material placed in a first compartment through a second and a third compartment; a means of washing said material from a site internal of said material and a site external of said material; a means of recycling small particulate matter to an influent before a suitable screen.

Preferably said means of progressing said material comprises a means for outletting water to the surrounding material.

Preferably the chassis comprises a substantial network of piping for water is passage and a plurality of suitable outlets for outletting water to said received material during or prior to a compaction stage.

Suitably, a coupling exists attached to said attached shaft rotated by said motor which allows for continuous water inflow to a central passage extending between said attached shaft and a means of progressing said material within said compactor. The attachment device preferably does not rotate with the attached shaft.

Brief Description of the DrawiM

For a better understanding of the invention and to show how the same may be carded into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which:

Fig. 1 shows a flow scheme detailing typical steps in the treatment of sewage and the disposal of the waste materials removed.

Fig. 2 illustrates a flow scheme according to a first specific embodiment and first specific method showing waste material screened from an influent being transferred to a compactor for washing and compaction. Recycling of small particulate matter is included, as is an output of compacted waste material.

Fig. 3 illustrates a plan view of a compactor showing three compartments, a 10 first end and a second end.

Fig. 4 illustrates a compactor in side view showing three compartments, a first end and a second end. Piping networks and apertures for inflow and outflow are also illustrated.

Fig. 5 shows a typical archimedes' screw used in a compactor with central space and apertures for outlet of fluid. A mounting shaft for accepting the bearings and motor also with a central space is also shown.

Fig. 6 illustrates a longitudinal section of a compactor showing an archimedes' screw, three compartments, a motor unit and mounting shaft.

Fig. 7 illustrates a sectional view of a typical aperture forming one of the slots in a first compartment.

Fig. 8 illustrates a sectional view of one of the inlets for water or other fluid for external washing of the waste material being compacted.

Fig. 9 illustrates a sectional view of an aperture through which small particulate and faecal matter can escape following washing in the rinse compartment.

Fig. 10 illustrates a view of the compactor from a first end, excluding the motor unit. The substantially cylindrical metal tube is illustrated 1001, as is the mounting for a chute 1002 to transport material to the first compartment, the surrounding chassis 1003 is also illustrated. Holes for attachment to the motor unit are shown surrounding the central tube.

Detailed Description of the Best Mode for Carrying Out the Invention

There will now be described by way of example the best mode contemplated by the inventors for carrying out the invention. In the following description numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent however, to one skilled in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the present invention.

Sewage processing is a multi-step procedure which aims to remove virtually all solid matter from incoming untreated sewage whilst also decreasing the microbe population in the sewage so that clean water can be returned to water courses without having adverse affects on the fresh water environment. Fig-1 details the basic steps in a majority of sewage processing plants. Untreated sewage 101 is screened 102 to remove large solids which often include items of domestic rubbish, these solids are removed and are often subject to a compaction step 109, compacted solids subsequently being disposed of at landfill sites 108 or alternatively they may be burnt. Following screening, the remaining sewage is subject to a primary settling stage 103. Here, remaining solids and faecal matter are allowed to settle and form a sludge 110. The remaining liquid, now termed the effluent 104 is usually subject to one of a number of filtration steps eg biological filtration 105 and then subject to a secondary settling stage 106 which removes any remaining particulate matter. Following one of a number 5 of possible further treatment steps clean water may be returned to the rivers 107. The sludge 110 formed during the settling stages is subject to an anaerobic digestion step 111, the remaining solid matter is collected and dried 112. This solid matter is of varying usefulness and hence may simply be taken to landfill or alternatively may find use as a fertilizer 113.

The inventors have considered the stages of screening 102, resulting in retaining large solids suitable for compaction 109 with the aim of disposing of the compacted solids at landfill sites 108. In view of increasing landfill taxes, the inventors have foreseen that minimizing the volume of waste solids taken to landfill will reduce costs involved in sewage treatment and will be of benefit to those companies concerned with sewage treatment.

The inventors have seen that prior art compaction of solids provides a means of reducing volume of waste solids taken to landfill, further however, they have realized that particulate matter accompanying large solids from the coarse screening to compaction stages may be suitably returned to a pre- screening stage of sewage treatment such that they may progress beyond a coarse screening 102 stage to a primary settling stage 103. In this way such small particulate and faecal matter can be incorporated in the sludge 110 and may therefore consequently find use as either fuel eg through methane gas produced during an anaerobic digestion stage 111 or as a fertilizer 113 following a collection and drying stage 112. A recycling of the particulate solids and liquid which accompany the large waste solids from coarse-screen compaction may therefore serve a twofold benefit. That is, a reduction in volume of solids being taken to landfill and hence costs involved through landfill tax. Secondly, the particulate matter removed from the large waste solid compaction may be made use of either to aid the efficient running of the sewage processing plant by the use of methane gas from anaerobic digestion used as a fuel supply 114 and hence a power source for the processing plant or through the production of fertilizers. In this way, the processing plant may be run more efficiently or to produce a commercially viable product without compromising the quality of the water returned to the water ways.

To facilitate the foreseen benefits of removing particulate solids and faecal matter from the large waste solids at a compaction stage 109, the inventors have included a washing step during compaction. Prior Art compactors have incorporated external washing devices washing the external surface of the waste solids being compacted. Such devices do not result in waste solids being washed throughout and hence do not result in the maximum possible removal of particulate and faecal matter from the solids to be compacted and therefore do not provide the greatest possible reduction in volume of the compacted solids and therefore do not enable a reduction in the volume of solids for landfill compared to that possibility. These failures to achieve a maximum efficiency result in higher prices for landfill. In particular, as landfill taxes are often higher for objectionable solids which may present a hazard to the environment or to workers handling the material in question the inventors have realized the advantages provided by clean washed screenings.

Raw sewage (Influent) entering a processing plant is likely to be subject to a number of screening steps such as the coarse screening 102. A number of different screens exist, with varying mesh size and methods of removing waste materials adhering to the screen. Such screens include raked screens, drum screens, rotary screens, storm overflow screens and brush screens. Fig. 2 illustrates a travelling fine screen 203 wherein raw sewage 201 approaches the screen where large particulate matter and other large waste materials adhere to the screen mesh and are prevented from proceeding 202. This type of screen is mounted on a travelling circuit such that the screen moves uni- directionally as indicated by the arrows on Fig. 2. At one end of such a screen, a brush or rake removes the materials which are adhered to the screen mesh and removes the waste solids. These solids and other waste materials are collected in a suitable container 204 prior to their disposal. A coarse-screen 203 results in the influent 205 being substantially free from large waste solids. The screen can be configured to allow only matter of a certain size to pass through. Typically, such a coarse-screen will have a uniform mesh size for example a circular mesh of 6mm diameter. Waste material collected from a screen may be suitably transferred eg by steel tubing 206 to a suitable compactor unit.

A compactor comprises a chassis housing at a first end a motor 208 adjacent to a first compartment which is in turn adjacent to a second compartment which is adjacent to a third compartment. Said third compartment is at a second end of said compactor. Within said compartments there is housed an archimedes' screw 209 and substantial piping for the transport and outlet of water. Said motor 208 is attached to said archimedes' screw at one end by means of a separate mounting shaft and said motor 208 operates in use to rotate said arch imedes' screw 209.

Referring to Fig. 3, showing a plan view of a compactor unit illustrating three compartments 303, 305 and 307. The motor unit is not illustrated in this figure but is normally adjacent to a first end 301. Compartment one, 303, comprises a large aperture formed by a frame 302. Said frame 302 houses a plurality of small apertures 304. Said frame 302 and apertures 304 provide a means of locating and securing a steel chute to the compactor by locating suitable bolts or other fastening means through said apertures 304 and securing using an appropriate fastening means eg a nut. Compartments two, 305 and three, 307 are formed from a substantially cylindrical metal tube through which said archimedes' screw 209 extends. Said substantially cylindrical metal tube may be open at each of two ends such that said archimedes' screw can pass continuously from compartment one, 303 through compartments two, 305 and three, 307. Compartment two, 305 comprises apertures 306 in said substantially cylindrical metal tube. Said apertures 306 are suitable for receiving a means of inletting water into said substantially cylindrical metal tube. Said means of inletting water may take the form of a tube or pipe or a suitable nozzle. Compartment three, 307 further comprises a plurality of suitably sized apertures 308 in the wall of said substantially cylindrical metal tube providing a means of outletting material, for example small particulate and faecal matter.

Fig. 4 shows the same compactor unit as illustrated in Fig. 3 but from a side-on view. This shows a connection plate 301 for connection to an adjacent motor unit. In the base of compartment one, 303, a plurality of slots 401 exist throughout the chassis of the said compactor. Said slots 401 are suitably sized to allow liquid and small particulate matter to pass through. Such matter passing through said slots 401 is collected and returned to the influent 201 at a stage before screening. It is envisaged that said slots 401 and said apertures 308 in compartment three, 307 are of a size comparable or exactly the same as the mesh size used in the screening process. For instance, where a mesh size of 6mm has been used, said slots 401 and apertures 308 would be expected to be also of minimum width 6mm and diameter 6mm respectively at a point in contact with the waste material. These mechanisms allow for small particulate matter and liquid which has failed to pass through the screen due to screen blockage or due to adherence to larger waste matter to be returned to an influent 201 in order to be re-screened. In this way, small particulate matter below a defined mesh size used for screening should not ultimately be contained in compacted material taken to landfill. It is possible that small particulate material may go through a cycle of screening, compacting and return to the influent several times before passing through the screen and entering the effluent 205.

Referring to Fig. 4 herein, compartment three, 307 forms a rinse compartment. Substantial piping 402 contained within said chassis is configured to outlet water onto said substantially cylindrical metal tube forming compartment three, 307. In this way, small particulate and faecal matter being forced out through any one of the said plurality of apertures 308 is "rinsed" and removed from the surface of said substantially cylindrical metal tube. This matter is collected and returned 214 to the influent 201 and is subject to another screening step.

Large material not suitable for returning to the influent via said slots 401 or apertures 308 is thus compacted and propelled along said substantially cylindrical metal tube by said archimedes' screw 209. In this way, said material is propelled out of said compactor into an adjacent tube or chute, for instance a stainless steel tube 211. Material reaching this point compdses the waste material suitable for landfill. Said material is subsequently placed in a suitable container for transport to a suitable landfill site.

Fig. 5 illustrates said archimedes' screw 209 and a mounting shaft 501 which accepts the attached motor and bearings. Said archimedes' screw and mounting shaft are typically formed from a high grade steel. Said archimedes' screw may be formed from a steel tube or cylinder with a welded steel flight forming the screw. Regardless of the form of manufacture of said archimedes' screw or said mounting shaft, both units have a hollow cylindNcal section 502, such that the axis of said archimedes' screw and said attached shaft takes the form of a tube or pipe. Said axis forming a tube or pipe is continuous between said archimedes' screw and said attached shaft such that when operable a flow of water may be maintained between said attached shaft and said archimedes' screw 209. Said archimedes' screw 209 comprises two ends a first end adjacent to said mounting shaft 501 and a second end 503, distant from said attached shaft. At said second end 503, said shaft of said archimedes' screw 209 has a blanked end in the form of either an attached metal sheet or a machined end piece. Said end piece is designed to limit the flow of any fluid through said central hollow section of said archimedes' screw and said attached shaft. Further to this, said archimedes' screw contains a plurality of apertures or holes 504, which may be radial, in the wall of said shaft of said archimedes' screw. Said apertures are operable to allow outletting of fluid eg water from said central section 502 of said archimedes' screw to a site external of said archimedes' screw. Said apertures are located as sets of three, each set of three apertures existing in one circular plane of the shaft of said archimedes' screw. Each of said apertures within each set of three apertures is located at a 120' angle from said nearest adjacent aperture. Said apertures may be present at any point along said shaft of said archimedes' screw. However, in this embodiment, it is considered that the portion of said shaft of said archimedes' screw extending through compartment one, 303 exists without any of said apertures in said shaft. That is to say that said apertures are evenly distributed throughout a region of said shaft of said archimedes' screw extending through compartments two, 305 and three, 307.

Fig. 6 shows a sewage compactor containing the archimedes' screw 209 as described above and illustrated in Fig. 5. Said archimedes' screw is designed such that it forms a close running fit into said substantially cylindrical metal tube forming compartments two, 305 and three, 307. Fig. 6 further shows the attached motor unit comprising the mounting shaft 603 for accepting the bearings and motor. Said mounting shaft houses a passage for transmission of fluid 502, said passage being continuous with said central space within said shaft of said archimedes' screw 502 for transmission of fluid eg water. Said space within said attached shaft for transmission of fluid is also continuous with a rotary union coupling 602 which connects a fluid input eg a water pipe 601 with the internal space 502 of said mounting shaft 603. In this way, water may enter said central passage 502 of said mounting shaft and in turn said central space 502 within said shaft of said archimedes' screw 209, exiting through one of said apertures 504.

Waste material 206 entering compartment one, 303 through chute 604 is received by the surface of said archimedes' screw 605. When operable, saidmotor 208 operates to rotate said archimedes' screw 209 in either a clockwise or anti-clockwise direction, depending on the handedness of said archimedes' screw. Rotating said archimedes' screw provides for movement of said waste material along said compactor in a direction from compartment one, 303 towards compartment three, 307. Excess liquid and small particulate and faecal matter may be drained from compartment one, 303 via slots 401 and can be returned to the influent 201. Material entering compartment two, 305 is subject to washing from water entering said compartment via said apertures 504 in the central shaft of said archimedes' screw 209. Said apertures 504 each housing a nozzle unit for water injection into said surrounding material. Water may also be forced into said compartment two, 305 through apertures 306 in said substantially cylindrical metal tube, each aperture 306 being connected by substantial piping to a suitable water supply (not shown in any diagram). By this mechanism, material being propelled from compartment one, 303 to compartment three, 307 is substantially washed by either one or a combination of the inputs of water into compartment two, 305. Said washing removes any further small particulate or faecal matter or other loose material from said waste material present in compartment two, 305 and may act to further breakdown this material. Material being propelled from compartment two, 305 to compartment three, 307 is further subject to washing by water being outlet from said central space 502 of said shaft of said archimedes' screw 209, this aids the forcing out of small particulate and faecal matter with a diameter equal or below that of said small apertures 308 in the wall of said substantially cylindrical metal tube of compartment three, 307. Any material forced out through said apertures 308 is subsequently rinsed by water being outlet from apertures or other suitable outlets in said substantial piping 402. Said rinsed matter is collected by a collecting tray below the compactor and returned 214 to said influent 201 for further screening.

Fig. 4 illustrates a plurality of apertures 306 on the surface of said substantially cylindrical metal tube within the region defined as compartment two, 305. These said apertures 306 are suitable for inletting a fluid, typically water into the substantially cylindrical metal tube. Said apertures 306 may house a suitable nozzle 801 and adaption mechanism used to connect said nozzle housed in said aperture to a network of substantial piping connected to a water supply. Said piping is operable in use to supply water through any of said apertures 306 and therefore to said interior of said substantially cylindrical metal tube and the material contained within. Said apertures 306 are depicted in figs. 4 and 6 to be at an upper surface of said substantially cylindrical metal tube. Although this may be the most appropriate site to place said apertures to obtain efficient washing of is said material within said substantially cylindrical metal tube, the placement of said apertures at the surface of said substantially cylindrical metal tube within compartment two, 305 is not restricted to these sites and indeed may be at any point within any of compartments one, 303 to three, 307 or any other surface of said compactor.

Outletting of fluid from said central space 502 in said shaft of said archimedes' screw 209 through apertures 504 is designed to provide a means of internally washing said material, whilst the inletting of fluid, typically water through said apertures 306 is designed to provide efficient washing of said material by an external means. The combination of said internal and external washing means is designed to provide a thorough washing of all of said material throughout. Not only does the washing of waste material such as that collected through screening of raw sewage enable the efficient recycling of small particulate and faecal matter such that this matter passes through said screen and is removed at subsequent processing stages, but the efficient washing of said material provides an important environmental benefit.

The Biological Oxygen Demand (BOD) is the mass of dissolved oxygen taken out of solution by a water sample incubated in darkness at 20'C for five days. It is a measure of the polluting capacity of an effluent or waste material due to the oxygen taken up by microbes as they decompose the organic matter contained within the waste material. The greater the BOD, the greater its potential for reducing the level of oxygen in the material. The organic material present in an effluent is oxidized by microbes using up available oxygen. Effluents or wastes can therefore be classified according to how much oxygen they require for the breakdown of the organic matter that they contain. Thorough washing of waste material during compaction as envisaged using an internal washing and external washing step provides the ability to decrease the BOD of waste material entering compartment one, 303 from 150 mg/g dry solids to 15 to 20mg/g dry solids. This type of reduction in BOD of around 87% is sufficient to significantly reduce the biological hazard of the final compacted waste product and hence is far more attractive a product to dispose of at landfill sites. In particular, it can be disposed of as a standard waste product without having special restrictions applied and higher prices for disposal.

Fig. 7 illustrates a sectional detail through one of the slots 401 in the base of the chassis 701 within compartment one, 303. The slot is designed to act as a further filter with the smallest width of the aperture forming one of the slots being of comparable size to the size of aperture used on the mesh forming the initial screen. For example, a coarse-screen using a mesh diameter of 6mm would require a minimum slot width of 6mm also. This allows for small particulate matter and liquid being screened due to adherence to larger solid or semi-solid matter or for any other reason to be recycled to join an influent 201 and be re-screened.

The minimum slot width could be changed during design of the compactor to be of an appropriate size for the size of mesh to be used on the initial screen.

Fig. 8 shows a detail of a section through compartment two, 305 showing one of the apertures 306 providing a means of inletting a fluid, typically water, into the substantially cylindrical metal tube 802. Said inlet could take the form of a nozzle or other means by which substantial piping maintained within the chassis of said compactor, external to said substantially cylindrical metal tube could be securely connected to said inlet forming a sealed entrance for water or other fluid into the internal portion of said substantially cylindrical metal tube. Said inlets are typically to be placed on an upper surface of said substantially cylindrical metal tube, however the invention is not to be limited by this factor and it is envisaged that said inlets may be positioned at any point around the circumference of said metal tube and at any point within said compactor.

Fig. 9 illustrates a sectional detail through one of the apertures 308 through which small particulate matter and liquid which is subject to compaction within compartment three, 307, the rinse compartment, of said compactor may be forced out. Said apertures 308 have a minimum diameter comparable to that used for said slots 401 and the mesh diameter for said initial screen. This adds a further means of recovering any small particulate matter and/or liquid which has further adhered to other waste matter or the surface of said compactor eg the flight of said archimedes' screw 209. Water being outlet from said substantial piping 402 is used in operation to wash away any of said small particulate matter or liquid being forced out through one of said apertures 308 and thus performs a rinse function. It is envisaged that twelve of said apertures as shown in fig. 9 would be present, equally spaced throughout a circular cross-section of said rinse compartment. Seven of said circular sections each containing twelve of said apertures equally spaced ie each 30" apart would be considered to be present on said rinse compartment. Typically, seven sets of twelve apertures each set of twelve being in a circular cross-section are envisaged to be present, forming a total of eighty-four apertures in the surface of said metal tube within said rinse compartment. However, the invention is not limited either by the number, size or distribution of said apertures present in said metal tube within said rinse 5 compartment or anywhere within said compactor.

Fig. 10 illustrates a compactor unit viewed from a first end 301 without an attached motor unit. A central cylindrical tube 1001 is present surrounded by a circular plate 301 suitable for attachment to a motor unit 208. The archimedes' screw is not shown in this illustration. Mountings 1002 for a chute 604 or other means of transporting waste material to a first compartment are shown. The chassis outline 1003 is also shown, the chassis being of greater height than the individual compartments to accommodate the networks of piping required to supply water to suitable inlets for washing and suitable outlets for spraying a third compartment 307, the rinse compartment, in order to rinse away material extruded through any one of the apertures in said rinse compartment.

In a first specific embodiment of the present invention there is provided a compactor comprising a chassis housing three compartments 303, 305, 307 through which a substantially cylindrical metal tube 1001 with interior space passes. Said compartments are arranged in a line with said tube passing throughout all of said compartments and extending beyond said compartments at both a first end 301 and a second end 211 of said compactor. Within a first compartment 303, said substantially cylindrical metal tube 1001 has an upper portion of said tube removed along a substantial length of said first compartment providing a means for inletting material into said tube. Within said first compartment, a plurality of slots 401 in the base of said tube provide a means of outlet for small particulate matter or liquid. Said first compartment 303 is adapted to receive a vessel 604 used for the transport 206 of material to the compactor such that material is continuously transported to said compactor and received by said compactor within the first compartment 303. Extending substantially the length of said compactor from a first end towards a second end and through said metal tube there exists an archimedes' screw 209 comprising a central shaft 505 and external flight 506 wherein said shaft and flight may be integral parts or may 5 be comprised of a tube with a welded flight. Extending the length of said shaft 505 forming said archimedes' screw 209 from a first end 507 extending towards a second end 503 there exists a central passage 502 suitable for passage of water. Said passage is blocked at a said second end 503. Present in the walls of said archimedes' screw, there exists a plurality of radial apertures 504 allowing for the outlet of fluid or water to the internal space of said metal tube. At a first end said archimedes' screw is securely fixed to a motor unit by a separate mounting shaft 501 also containing a continuous internal space 502, which forms a continuous passage with said central passage of said shaft of said archimedes' screw 209. Said mounting shaft 501 is further connected to a water supply 601 providing is inflow to said central passage throughout both said mounting shaft 501 and said archimedes' screw 209. Said motor unit is attached to said compactor at a first end of said metal tube and operates in use to rotate said archimedes' screw within said metal tube. Rotation of said archimedes' screw provides a means of propelling material, inlet to a first compartment 303 through an opening in the upper side of said metal tube within said first compartment. In this way, material received in a first compartment is propelled throughout said metal tube to a second compartment 305 and a third compartment 307 and ultimately out to a second end of said metal tube 211.

Within said second compartment said metal tube contains a plurality of apertures 306 which provide a means for water or fluid in-flow to the internal space of said metal tube. Said apertures are connected to a water or fluid supply by means of a substantial network of piping within said chassis of said compactor. Said piping is further connected to an external water or fluid supply.

Rotation of said archimedes' screw propels said material from a first compartment 303 to a second compartment 305. In said second and third compartments said received material is subject to washing by water or fluid inlet to said internal space of said metal tube by water outlet from said central space of said shaft of said archimedes' screw. This may be in combination with water inlet to said 5 central space through said apertures 306 in said metal tube.

Water inletting to said central space from said apertures 306 in said metal tube acts to wash said received material, breaking down a proportion of said material to smaller particulate matter. Rotation of said archimedes' screw propels said material through said second compartment 305 to a third compartment 307.

Said third compartment being formed by said metal tube housing a plurality of apertures 308 suitable for extrusion of any liquid or small particulate matter present within said metal tube due to material breakdown as a consequence of washing removing small particulate matter previously adhered to larger solid and semi-solid matter. Substantial piping external to said metal tube within said third compartment 307 comprising a means of outletting fluid or water onto said metal tube and said apertures provides a means of rinsing away small particulate matter and liquid extruded from said apertures. Material remaining within said metal tube is further propelled by said archimedes' screw 209 to a second end of said metal tube. Said material is now compacted and has been washed and may be removed from said compactor by means of another adjacent substantially cylindrical metal tube 211 attached to a second end of said compactor. Said attached tube providing a means of progressing compacted, washed and dewatered material to a suitable container prior to said compacted and washed material being transported to a suitable site for disposal eg a landfill site.

Said compactor operates in use to compact material input to a first compartment 303 and output to a second end of said compactor from an initial volume of 100% to a compacted volume of approximately 30% thus a substantial reduction in volume of said material and increase in the density of material is achieved. This is of benefit when considering the volume of waste material required to be disposed and the price of doing so.

Due to the nature of compaction and the means by which said archimedes' screw 209 maintains a uni-directional flow of said material from a first end to a second end of said compactor a high water pressure is required both within said shaft 505 of said archimedes' screw and through said nozzles in said apertures 504 of said shaft and through said substantial piping and inlets 306 in the wall of said metal tube within said second compartment 305. To obtain a thorough washing of said material and hence to provide a substantial decrease in the Biological Oxygen Demand and volume of compacted material it is found that a water pressure of approximately 6 or 7 bar is required. To obtain these pressures, an external booster pump is required on said water or fluid supply to both said central space 502 of said mounting shaft 501 and said shaft of said archimedes' screw 505 and also to said supply of said substantial piping connected to said inlets 306 in said metal tube of said second compartment 305. In order to withstand water pressures of approximately 6 or 7 bar said archimedes' screw and said separate attached shaft are envisaged to be made from a suitable high grade steel or other suitable material. Using a water pressure of approximately 6 or 7 bar a decrease in the Biological Oxygen Demand of waste material inlet to a first compartment can be reduced from approximately 150 mg/g dry solids to approximately 15 to 20 mg/g dry solids. This significantly reduces the biological hazard of said compacted waste material which can be deposited at a landfill site.

In a first specific embodiment of the present invention, in order to best accommodate a thorough washing of said material within said compactor said archimedes' screw 209 is considered to have a shaft 505 of external diameter of approximately 4" or approximately 102 mm comprising a thin wall of approximately 15 mm, leaving an internal diameter in the region of 3" or approximately 76 mm. These dimensions are not limiting and can be varied substantially to obtain a required quality of washing for a suitable purpose. However, dimensions as stated should provide for a fluid or water outflow through said apertures 504 in said central shaft of said archimedes' screw in the region of 5 approximately 2 liters per second (or 120 liters per minute).

Although said inlets 306 in said metal tube within a second compartment are only expected to be present within a second compartment 305 or comparable compartment, they may be present at any point along said compactor. The first specific embodiment considers outlets for water outflow from said central shaft 505 of said archimedes' screw to said central space of said metal tube are present in said archimedes' screw in the region of said archimedes' screw extending between said second compartment 305 and the second end of said archimedes' screw 503 within said third compartment 307 and closest to said second end of said compactor. This is not limiting however, and outlets for water flow into said metal tube may be present at any point along the length of said archimedes' screw or said separate mounting shaft 501.

The running specifications of the compactor described, for instance flow, pressure and nozzle size are not be construed as limiting the invention. Indeed these and other specifications included in the compactor are variable and may be changed to suit the required specification of each individual compactor. That is to say that compactors are often installed at sites which differ in their spatial arrangement or supply arrangements etc.

In a first specific method of the present invention material received in a first compartment by a suitable archimedes' screw 209 is moved unidirectionally towards a second 305 and a third compartment 307 of the compactor. Said archimedes' screw is rotated by a suitably attached motor unit 208, said motor unit being connected to said arch imedes' screw by a suitable mounting shaft 501.

Rotation of said archimedes' screw results in the movement of material received in a first compartment 303 to a second 305 and then a third compartment 307.

Water entering said compactor enters a continuous passage 502 between a suitable mounting shaft 501 and said archimedes' screw 209 wherein said suitable mounting shaft 501 acts to link the said archimedes' screw 209 to a motor unit 208. Water inlet to such a suitable passage 502 within said mounting shaft 501 and the shaft of said archimedes' screw 505 is outlet through nozzles located in radial apertures 504 located at specific points along the length of the shaft 505 of said archimedes' screw 209. In this way, water is outlet to a surrounding received material and acts to wash said material. The said material may include sewage or a by-product of sewage.

A substantial network of piping configured to transmit and outlet water to is said received material further acts to wash said material.

Either material washing by a water outlet from nozzles in apertures 504 present in said shaft 505 said archimedes' screw 209 or a combination of water so outlet to said received material and water outlet from a substantial network of piping to said material through inlets 306 acts to substantially breakdown any loose or solid material within the said compactor. Following washing, the excess liquid and small particulate matter contained therein may be drained and recycled to a suitable influent 201. Particulate matter for recycling to a suitable influent 201 is selected by suitably sized apertures including slots 401 in the chassis of the said compactor.

Within a second 305 and a third compartment 307 said archimedes' screw 209 acts to compact the material received in compartment one, 303 at a point simultaneous to that of the described washing procedure. In a said third compartment 307, compaction and washing combine to force material contained therein to the wall of the said third compartment and suitably small particulate matter and liquid may be expelled from said compartment through any one of a plurality of apertures 308 in the substantially cylindrical metal tube forming said compartment. Material forced out through any one of these said apertures is subject to a rinse procedure wherein water is outlet from a substantial network of piping 402 transporting and outletting water on to the said third compartment. The rinsed matter is suitably recycled 214 to an influent 201.

The action of said archimedes' screw is such as to propel material maintained within the said third compartment to a second end of the said compactor and when operable in use to a connected member eg a suitable pipe for transport to a suitable container prior to disposal.

Claims (24)

Claims:

1. A device configurable for use in compacting a material, said device having a fluid transmission member wherein said fluid transmission member comprises a surface configurable for receiving said material and said surface 5 comprising a means for outletting fluid to said received material.

2. A device as claimed in claim 1, comprising:

a chassis containing:

one or more compartments containing:

a fluid transmission member; a motor.

3. A device as claimed in claims 1 and 2, where said fluid transmission member has a first end and a second end, said first end being attached to said motor, said second end laterally displaced from said first end, extending through one or more compartments.

4. A device as claimed in any of claims 1 to 3, wherein said fluid transmission member contains one or a plurality of apertures configured to outlet fluid to said received material.

5. A device as claimed in claim 4, wherein each aperture houses a nozzle unit.

6. A device, as claimed in any of claims 1 to 5, where said fluid transmission member incorporates a central shaft with internal space for passage of fluid.

7. A device as claimed in claim 6, wherein said motor is operated in use to rotate said fluid transmission member.

8. A device, as claimed in claim 7, wherein said motor is connected to said fluid transmission member by a mounting shaft.

9. A device, as claimed in claim 8, wherein said mounting shaft has an internal space throughout its length so that when operable in use said internal space is continuous with the internal space within said fluid transmission member.

10. A device as claimed in any of the previous claims, wherein the internal space within either the mounting shaft or said fluid transmission member can be suitably connected to a fluid supply to provide fluid flow through said internal space, exiting through said nozzles in said apertures.

11. A device as claimed in claim 10, wherein said fluid supply is connected to said mounting shaft or said fluid transmission member by means of a rotary union.

12. A device as claimed in any preceding claim, wherein said chassis houses substantial piping with a means for outletting fluid to said material.

13. A device as claimed in claim 12, wherein said fluid transmission member is operable in use to move said matedal into an adjacent compartment for compaction of said material.

14. A device as claimed in claim 13, wherein said compartment for compaction of said material has surface apertures to allow restricted outlet of material under compaction.

15. A device as claimed in any preceding claim, wherein said fluid transmission member is suitable to support in operation a water pressure of 7 bar.

16. A device as claimed in any of claims 1 to 15, wherein said fluid transmission member is operable as an arch imedes' screw.

17. A device as claimed in any preceding claim, wherein said nozzles are capable of providing a water flow of 2 litres per second.

18. A device as claimed in any one of the preceding claims, capable of compacting waste solids to 30% of their original volume.

19. A device as claimed in any one of the preceding claims, capable of 20 decreasing waste material Biological Oxygen Demand by 80%.

20. A device as claimed in any one of the preceding claims, wherein said fluid is water with or without any suitable additives.

21. A device as claimed in any one of the preceding claims, wherein said material is sewage or a by-product of sewage.

22. A method of processing a material prior to and during compaction, said method comprising the steps of:

-31receiving said material on the surface of a fluid transmission member; outletting fluid from a fluid transmission member to said material.

23. A method according to claim 22, further comprising the steps of:

outletting fluid onto a fluid transmission member; rotating said fluid transmission member wherein; said fluid transmission member may be an arch imedes' screw.

24. A method as claimed in claims 22 and 23, wherein said fluid is water with or without any suitable additives. is