MXPA99010290A - Continuous composter having self-contained aeration zones - Google Patents

Abstract

A continuous composter (10) is provided with self contained aeration zones (Z1, Z2) so that air circulation is confined to any one zone to avoid transmission of bacteria through a composting tunnel (12). An inlet fan (46A, 46B) and an exhaust fan (48A, 48B) are provided for each zone and suction through the exhaust fan is provided stronger than inlet pressure so that gases do not percolate through the tunnel (12). Similarly water and leachate are remoded from the system without contact with downstream composting garbage. Any recirculation of gas or leachate takes place only in the zone from which it has come.

Description

COMPOSTA CONTINUES THAT HAVE SELF-CONTAINED? DOR? S COH VENTILATION ZONES DESCRIPTION D? THE INVENTION This invention relates to an apparatus and "method for composting from waste." At least from environmental considerations, attention has been paid to the undesirability of discarding the waste as a landfill, the importance of the formation of waste. Compost has been increased Several small-scale and industrial composting systems have been developed to take the place of the compost accumulation of the traditional backyard, and proposals have been made for continuous composting apparatus within which the waste at one end and from which compost emerges at the other end.Such apparatus, especially large-scale apparatus, has suffered problems in advancing the waste through the apparatus.An example of such an apparatus comprises a tunnel-- having a hopper power supply on one end and an output on the other end. to force the waste that composts through the tunnel to pass over a stationary floor. The gate has a tendency to pack the waste and thus prevent ventilation, which is necessary to form a successful compost. Another system for composting which allows the necessary ventilation involves pulling the waste that compost composes - through a tunnel through a network. This system, however, is a batch system and it is necessary to complete a batch of compost before starting another batch. Frequently, in known compost-forming systems, the flashlight creates a problem. It is not considered desirable for health or for aesthetic reasons to use systems to form open composts, since the odors of the decomposing waste can cause health problems as well as being unpleasant. One such system is described and claimed in French Patent No. 2,519,966. The removal and recycling of harmful gases has also provided problems in the past. The tunnel co-ers, such as the one described above, simply ventilate the gases that are emitted. More recently, U.S. Patent Nos. 5,409,831 and 5,551,969 were granted in 5,409,831 and 5,551,969 respectively to James Wright for a continuous composting system. includes a tunnel to form "closed" compost that inhibits the escape of harmful gases. The waste is loaded into a perforated tray upstream of a tray train in the tunnel. The trays are moved "stepwise" through the tunnel, each step is started when the upstream tray is fully loaded and replaced by a new empty tray upstream.The compost formation is carried out continuously in the tunnel and water and air are added as necessary, and mixing is carried out at least at one point along the tunnel.This system has several advantages over previous systems in which the gases and liquid ejection can be removed, and filter before returning them to the atmosphere During the formation of compost, the temperature increases to values suitable for the formation of compost, which can be high enough to kill any bacteria present, however, in some areas of the composter, temperatures they are lower and there may be a risk that the bacteria can be transferred through the composter by means of, for example, air or liquids through The material that compostes. "Since the eventual composter can be intended for free use by unprotected individuals, it is desirable that it be sterile and safe to use, since the waste feed for commercial compost may be of a known or bacterially contaminated origin., it is important that the destruction of bacteria is completely. Compost emanating from existing composters, even those as described in the aforementioned US Patents Nos. 5,409,831 and 5,551,969, may not meet these criteria. The present applicant has addressed the problem of solving a system for continuous compost suitable for composting on a small or large scale from food waste with or without the addition of other materials that are more difficult to compost such as wood sawdust, or still plastic. In particular, the problem of providing a system where bacterial contamination is minimized has been addressed. According to the invention there is provided a continuous composter comprising: a closed elongated tunnel having a first end upstream and a second end downstream; an entrance for waste in the region of the first end; an exit for the compost at the second end; the composter comprises at least one compost-forming area upstream in the region of the first end of the tunnel, and a compost-forming zone downstream in the region of the second end of the tunnel, the first compost zone and the second compost zone.; first self-contained means for ventilating the upstream compost forming zone and for recirculating a portion of ventilation aeration gases within the upstream zone and second self-contained means for venting the downstream compost forming zone and for recirculating a portion of the exhaust gases. Ventilation ventilation within the downstream area. There may be one or more additional composting areas, each having self-contained ventilation means. The upstream and downstream zones can be separated by intermediate zones, mixing with the upstream and downstream zones, but tending to minimize any air exchange between the zones. A portion of the exhaust gases and vitiated vent gases can be recycled within each self-contained ventilation system. Such recycling can provide adequate treatment for bad smelling gases. The proportions of recycled gas and fresh air can be maintained by computer. However, it is important that the recycling be confined in any of the composting areas. The composter may preferably be of the type described and claimed in U.S. Patent No. 5,409,831 and U.S. Patent No. 5,551,969. For example, the composter may include a raised conveyor track of a tunnel floor and extending along the length of the tunnel; "a train of conveyor trays traveling in the derivative direction on the conveyor track, each tray having a derived structure to receive a directional bypass force and each tray has a foraminous carrier surface ~ to allow ventilation of the material in the tray; a gate having a movement in the direction of an elongated axis of the tunnel, the length of the movement is equal to the chosen length of the diverting passage of the conveyor trays, the gate is positioned to act against the structure derived from the conveyor tray which it is further away upstream. Mixing means are provided at the first end upstream of the composter. The mixing means comprises a channel comprising an elongated section of a cylinder having an open mouth, an elongated base convex towards an outer surface of the tray, the tray being located through the upper surface of the tunnel below the entrance for the containers. waste and being tiltable around-from an elongated axis of the punt between a first position in which the open mouth is facing upwards for the reception of the debris inside the tray for its retention in this, and a second position in which the open mouth is looking down to empty the waste from the pan into the waste entrance, the pan has mixing propellers to mix the waste in the pan. The trough can be tilted by means of gear teeth on an outer surface of the trough engaging with gear teeth complementary to the activating means for this. The mixing propellers can be activated in opposite directions to intimately mix the debris that is present in the pan. A lid can be provided to close the open top of the pan when it is facing upwards to confine the odor of the waste within the pan. The lid can be opened to allow the supply of waste to the pan which is pivoted to empty the waste into its tunnel entrance. If the lid is freely hinged on a flange, the pivot of the pan can raise the lid automatically. The tunnel may have generally parallel side walls and the conveyor track may comprise a pair of rails. The conveyor trays can have a generally rectangular shape, and have a width between the diverting wall and an opposite wall equal to the length of the movement of the gate. Conveniently, the conveyor trays are provided with slidable runners to be supported on the conveyor track. Alternatively, the rails may have slidable surfaces in which the trays can slide. However, it is more convenient to provide these surfaces in the trays, since wear can be checked more easily. The base of the conveyor trays may be a perforated sheet metal or net or other foraminous material. The outlet of the tunnel can be provided with closing means which can be opened by pressing a moving conveyor tray such as a freely hinged door. The mixing means can be provided in the tunnel to mix the waste composing. The mixing means may comprise mixing rollers extending from one side of the tunnel to another and having, for example, blades for mixing the waste. Conveniently, the mixing means are provided in an intermediate zone by separating the first and second compost-forming zones, or in regions of high temperature where there is little risk of contamination of bacteria from one zone to a downstream zone. The blades can be angled to one side or the other of the tunnel to encourage cross-mixing of the waste. In any other place, the mixing rollers can be provided, one on top of the other. Each mixer roll may have at least one first blade having a helical orientation on the roll to direct the waste in one direction and at least one second blade having an opposite helical orientation to direct the waste in an opposite direction. "Preferably , the adjacent blades may have helical turns in opposite directions to direct the waste in opposite directions with a view to the mixed waste in the transverse direction of the tunnel.Alternately, each blade may be a vertical flange having its plane at right angles to the axis of the roller, a number of tabs can be arranged around the roller spaced apart to form a number of shallow helical bands.Each roller can have at least one first band with a helical orientation by a ----- side, and At least one second band with a helical orientation on the other hand Immediately downstream of the rod Before the waste has had time to settle and compact, water can be added to the waste in an amount to promote the formation of compost. At least one water sprinkler pipe can be extended through an upper region of the tunnel to sprinkle water in a descending water curtain. More preferably, at least two such pipes for the provision of two water curtains are provided close to one another. The separation between the pipes can be in the general range of 9 inches to 12 inches. Of course, it will be appreciated that in a smaller composter the water sprinkler pipes will have a tendency to be closer together. The percolate can be collected in separate self-contained drainage boxes for each zone and can be recirculated only within the area from which it comes. The invention also includes a method for composting that comprises depositing debris within a tunnel to compost through an inlet; in the region of a first end; remove compost from an exit at a second end of the tunnel; and separate ventilation zones upstream and downstream of the composter and recirculating a portion of stale ventilation gas only within the area from which it originated. B EVE DESCRIPTION OF THE DRAWINGS One embodiment of the invention will now be described by means of the example with reference to the drawings in which: Figure 1 is a schematic illustration from the side of a composter according to the invention; Figure 2 is a view of the foregoing showing the water and air supply system; Figure 3 is a schematic view through the composter of Figure 1 from one end; Figure 4 is an illustration of a movable tray that can be used in a composter as it is in that of Figure 1; Figure 5 is an illustration of another movable tray that can be used in a composter such as that of Figure 1; Figure 6 is a detail showing the movable tray located in a U-shaped channel; Figure 7 shows the pattern of air flow in the apparatus; and Figure 8 shows a possible percolation and water flow pattern in the apparatus. The drawings illustrate a composter 10 comprising a tunnel 12 having an upper part 13 and a trough with mixing hopper 14 at an upstream end 16 of the upper part 13. The trough with mixing hopper 14 is normally sealed to prevent escape of harmful gases. A conveyor elevates the waste to supply it to the hopper with mixer hopper 14. The downstream end 18 of the tunnel 12 has a door 20 for letting out the compost. The door is normally sealed shut. Within the tunnel 12, tracks 22 are provided on each side of the tunnel supporting conveyor trays 24. The conveyor trays 24 move in a stepwise fashion through the tunnel in a longitudinal direction in the conveyor tracks. A. Upstream conveyor tray 24 is located on tracks 22 under the hopper with mixer hopper 14. The waste is added from the conveyor to the hopper with mixer hopper 14 of which is supplied at a suitable depth in the tray 24, say a foot of the roof of the tunnel 12. The tray 24 is then advanced forward by the action of a gate 26 having a sufficient stroke to move the tray 24 forward sufficiently to allow space for an additional tray 24. The hatch 26 is then retracted and another tray 24 is inserted between the gate and the tray now filled 24. The number of trays and the length of the tunnel can be such that the compost formation is completed when a tray 24 reaches the end 18 of the tunnel. The compost can then be removed from the tray by a conveyor and the tray can be returned to the inlet end 16. The return of the tray can be manual or automatic. When the return of the tray is automatic, each tray leaving the tray exit port 21 can be driven on a conveyor to return the tray to a tray entry port 23. Conveniently, the size of the tunnel and the size of Trays can be such that each tray can cover a daily supply of waste. It is suggested that under good conditions of compost formation, fourteen days will be sufficient to make the compost and in this way the line of conveyor trays within the compost can be fourteen as shown. The operation of the composter will be described in greater detail with reference to the parts of the apparatus later. The compost loaded into the trough 14 may be food waste which preferably is mixed with bulk materials such as newspaper or sawdust. Shredded plastic can be mixed with food waste and is subject to the composting process. This can be an easy way to dispose of plastic waste which currently causes considerable problems. Shredded plastic having a particle size between 0.6 cm and 2.0 cm (between a-s and inch) can be used in proportions up to 1/3 of volume or even more of food waste. Each conveyor tray 24 comprises a structure and a foraminous surface 28 through which air can access the waste to be composted. The foraminous surface 28 is located on top of the structure. The trays are added to the train or to the trays at the end upstream of the tunnel 12 through a tray inlet port 23. The tray 24, on which one acts, by means of a composite 26 to make it advance one step inside the tunnel, acts on the tray 24 downstream of it to advance that tray 24. In this way, the trays are derived from the tunnel until the last tray 24 is drifted out of the tray exit port 21 which, except during the exit of a tray, can be sealed against the escape of gases. Since the trays are subjected to considerable pressures, initially imparted by the gate 26 against the structures, these structures are constructed to support these stresses The side wall of the structure 30 is high enough to be impacted by the front face The gate 26 conveniently gives access to most of the structures upstream through the tray entry port 23. In practice, it is not necessary for the walls 30 to be too high. vertical area to accommodate the driving face of the gate 26 to absorb all its force The other pair of the side walls of the trays located longitudinally in the tunnel are conveniently made as sturdy side walls 30. However, these longitudinal walls do not have to absorb all the force of the gate against its planes.

The opposite pair of longitudinal tray side walls run on the tracks 22 carried by the walls of the tunnel 12. Conveniently, the tracks 22 each comprise a U-shaped section channel, the network 35 which is fixed to the wall of the respective tunnel 32. The network 35 of the track 22 is wide enough so that the entire height of the tray can be accommodated within the U-shaped section, while resting on the U-shaped end of the carrier 37a and it is covered by the U-shaped end of the cover 37b. The tunnel 12 and the trays 24 can be sized according to the amount of waste to be handled. Given this, under good conditions, the formation of compost can be achieved in fourteen days, it is convenient to provide - one tray per day in the composter. Thus, if 90 kg (approximately 200 pounds) of waste is to be handled per day, the size of the tray and the size of the tunnel should be such that a tray will accept 90 kg (200 pounds) of waste. The size of the gate and the pressure of the gate must clearly also be properly adjusted to move the entire train of trays inside the tunnel. However, it is emphasized that a composter according to the invention may be intended for a very small domestic operation or for a very large industrial operation. The mechanics and engineering of tunnels and trays of adequate size is well within the reach of a person skilled in the art. As illustrated in Figures 1-3, the tunnel is effectively divided into two ventilation zones Zl and Z2. Three- or more ventilation zones are also possible.Overall, the operation of two zone systems or three or more zones is similar.A temperature sensor 32 is provided in each zone Zl and Z2.A ventilation system is provided in Each zone Zl and Z2 each comprise a vertical conduit 42A, 42B extending down through the tunnel 12 adjacent to its side rail, The conduits 42A, 42B suck air from the exterior by means of respective fans 46A, 46B. air is transported down the pipeline to below the level of the conveyor trays 24 within separate collectors 43A, 43B for each Zl or Z2 zone. From each collector 43A, 43B the air is distributed through the waste composting in the respective zone. An additional fan can be provided at the bottom of each conduit 42A, 42B. Exhaust fans 48A, 48B are provided in the upper part of the tunnel in each zone for the removal of air and gases produced from each separate zone during the formation of compost. A proportion of the exhaust gases from a zone can be added through the conduit 45 to the ventilated gas passing through the conduits 42A, 42B to their respective zones. It is important that the recirculation is confined to any of the zones to avoid the distribution of bacteria throughout the tunnel. The exhaust gases contain an appreciable amount of oxygen not used. And it is possible that, apart from the addition of oxygen, an effect of the recycling of exhaust gases is to improve the lightening effect of ventilation and help prevent and compact waste. Exhaust gases exiting the biofilter 36 can be passed through a final sterilizer 50, if desired. The location of the ducts 42A, 42B and the manifolds 43A, 43B with respect to the expulsion fans 48A, 48B in any zone is such that they confine the circulation to a single zone as shown in Figure 7. In fact, it can be It is convenient to separate the ventilation zones Zl and Z2 in which the ventilation is carried out by intermediate zones such as XI in which little or little ventilation is carried out. The air circulation is planned in such a way that the intermediate zone XI is not necessarily ventilated. Eventually, the ventilation gases they are removed by filtering them through a biofilter 36. The suction exerted by the expulsion fan 48 is greater than the inlet pressure exerted by the inlet fan 46 so that it tends to keep the zones Zl and Z2 separated. The pressures can be controlled by a computer 68. It may be convenient to provide mixers 60 in the intermediate zone XI to provide some lightening of the mass that compost composes where there is no rising air flow. Conveniently water is added as a curtain of water from a spray bar 102 extending through the tunnel 12. However, the recirculation of water should be equal to the air circulation being confined within any of the zones. The water from the spray bar 102 in, for example, the zone Zl can be infiltrated through the waste formed by the compost to be collected in a plenum 104. The floor 106 of the plenum 104 that slopes down to a lower channel 108 well below the bottom of the trays 24. The percolate flows down into the channel 108 and can be pumped by a sump pump 110. If it is desired to recirculate the percolate, the plenum 104 and channel 108 should be divided. in separate chambers 104A, 104B (see Figure 8) and the channels must correspond to zones Zl and Z2. A sump pump 110 should be provided in each division so that there is little opportunity for bacteria to be transferred between the zone by means of the recirculating percolate. A return line 112 of each sump pump 110 is provided. The amount of any recirculated percolate is controlled by computer 68. On the other hand, a non-return valve 114 must be provided in the sump pump line so that the Fresh water is not forced into the channel 108. It is important that the water is added at least immediately downstream of the mixing rollers 60 as long as the waste is still loose and not mixed or compacted. sprinkler 102 downstream of the mixers 60 is more important than the spray bar 102 upstream of the mixers 60. In practice, it has been found that two spray bars 102 are preferred, one separated downstream from the other. from the most downstream zone 22, the helices 62 are provided one on top of the other to transport the compost formed within an annex side tunnel. The propeller 62 falls on a conveyor and is removed through the sliding door 20. The entire process can be controlled by the computer through the computer 68. The computer 68 calculates and "controls the proportions of expulsion gas and of fresh ventilation gas supplied in each of zones Zl and Z2, in response to conditions such as the temperature inside the composter and can also control the opening and closing of the exit and entrance doors. Generally, it is only allowed to open the entry and exit doors when the waste enters or when the compost leaves the system. When this is not the case, the tunnel is effective and completely sealed. A port of entry is provided for trays 24 and an exit port is also provided; but, when the trays 24 are in the position within the tunnel 12, the structures effectively block and close the inlet and outlet ports for the trays. The computer 68 can also ensure that the pressure of the vent gas, with or without an exhaust gas component, is kept lower than the suction pressure that removes the exhaust gas. If the pressure inside the tunnel remains lower than the atmospheric pressure, any leakage in the system will not result in the escape of noxious odors. As the trays progress in a step-like fashion through the tunnel, the volume of the waste that compost composes decreases. In this way, the tray 24 is loaded inside, perhaps, one foot of the ceiling of the tunnel 12. This volume can be reduced to 40% of the original at the time that the tray has reached the position of the tray 24. It can be possible by the use of mixers, or by the use of additional helices, which act longitudinally, provide a certain mixer from tray material to tray without detriment to the composting process. Such mixing can help move the material to maintain a more uniform level in the tunnel. At least, the additional mixing can provide greater ventilation and lift and accelerate the formation of compost in the trays downstream. The volume and longitudinal dimensions of the tunnel are purely a matter of choice. It is for convenience that the system has been described by referring to a tunnel of one length to accommodate fourteen trays, one tray being used for each daily waste. If a regular supply of waste is available, this system is convenient for the operator without taking into account the amount of waste that is supplied daily. In this way, if an operator can rely on 90 kg (200 lbs) of daily waste, the system can be designed so that each tray can accommodate 90 kg (200"pounds) of waste, in which there is little need to check If a tray is overloaded or if "it is time to install a new tray. However, it will be appreciated that when the waste supply is irregular there will be a need to advance the train of trays only when the tray 24 directly under the hopper 14 is filled to an adequate capacity. The decision, as to when this point occurs, can be made by visual verification, or other automated means can be installed to warn the operator that a forward step of the tray train is desirable. Again, the choice of fourteen days (or fourteen trays) as the length of the tunnel is not in any way limiting. Under good conditions, compost can be done in fourteen days, but given adequate trawl strength and adequate gate strength there is no objection "for the compost to remain in the tunnel for a longer period of time. It will extend the length of the tunnel beyond the minimum necessary.

Claims (11)

1. CLAIMS 1. A continuous composter, comprising: a closed elongate tunnel having an upstream end and a downstream end; an entry for waste in the region of the upstream end; an outlet for the compost at the downstream end; at least one compost-forming zone in the downstream end region of the tunnel, and one downstream area of the compost in the downstream end region of the tunnel; first means for venting the upstream compost forming zone with vent gases while containing the gases within the upstream compost forming zone and for recirculating a portion of ventilation aeration gases within the upstream zone; and second means for venting the downstream compost forming zone with venting gases while containing the gases within the downstream compost forming zone and recirculating a portion of the venting aeration gases within the underflow current zone. or; a conveyor track elevated from the floor of the tunnel and extending along the length of the tunnel; a train of conveyor trays to travel in the direction of derivation in the conveyor track, each tray has a structure in the direction of derivation to receive the directional bypass force and each tray has a foraminous carrier surface to allow the ventilation of material in the tray; and a gate having a movement in the direction of the elongated axis of the tunnel, the length of movement is equal to the chosen length of the bypass passage of the conveyor trays, the gate is positioned to act against the bypass structure of the conveyor tray , which is furthest upstream, characterized in that each of the first and second ventilation means comprise: an air inlet at an upstream end of a manifold below the conveyor trays in one of the zones; means for passing air through the air inlet to each manifold; ejection fans located to extract gases from the collector through each of the zones; control means for maintaining the ejection suction stronger than the inlet pressure of the ventilation gases in this zone and on whose means are provided, to recycle a proportion of each of the respective air intakes for the zone; and means for recycling a proportion of gases within the respective zone of the air outlet to the air inlet. The composter according to claim 1, characterized in that it includes at least one area to form additional compost that has ventilation means for venting the additional compost forming zone while containing ventilation gases within the additional compost forming zone. and to recirculate a portion of ventilation aeration gases within the additional zone. 3. The composter according to claim 1, characterized in that the upstream and downstream areas can be separated by an intermediate zone without means of ventilation. The composter according to claim 1, characterized in that the expulsion duct means are provided for transporting gases from the exhaust fans to a filter. 5. The composter according to claim 1, characterized in that each conveyor tray has a generally rectangular shape, and has a width between the bypass wall and an opposite wall equal to the length of the movement of the gate. The composter according to claim 1, characterized in that the mixing means are provided in the tunnel to mix the waste formed by the compost. The composter according to claim 1, characterized in that the means are provided to add water to the waste in an amount to promote the formation of compost. 8. The composter according to claim 7, characterized in that the means for adding water are at least one elemental water pipe that extends through an upper region of the tunnel for spraying water in the form of a descending water curtain. 9. The composter according to claim 7, characterized in that the percolating collection chamber is provided below the trays. 10. The composter according to claim 9, characterized in that a pump is provided to remove the percolate from the collection chamber. 11. "The composter according to claim 9, characterized in that the separate collecting chamber is provided below the trays of each compost forming zone and means for recycling the percolation of the collecting chamber to the sprinkler pipe.