Aerobic composting device and aerobic composting method for organic solid waste
Technical Field
The invention relates to a device and a method for treating organic solid waste, in particular to an aerobic composting device and a composting method for organic solid waste.
Background
The organic solid waste comprises kitchen waste, sludge of an urban sewage treatment plant, straw, landscaping waste and the like. The main modes for treating organic solid wastes in the past are landfill and incineration, wherein the landfill easily pollutes underground water, and the incineration can seriously pollute the atmosphere.
The microbial aerobic composting is that under the aerobic condition, the aerobic bacteria absorb, oxidize and decompose the waste. The microbes oxidize part of the absorbed organic matter into simple inorganic matter and release the energy for the growth of microbes, and the other part of the organic matter is synthesized into new cytoplasm to make microbes grow and reproduce continuously to produce more organisms.
Compared with treatment modes such as incineration, landfill and the like, the organic solid waste is treated by using the microbial aerobic composting, so that secondary environmental pollution, food safety risks and methane explosion risks are avoided, and the method is one of clean technologies for solving the problem of the organic solid waste. In addition, a large amount of organic matters, elements such as nitrogen and phosphorus and the like in the organic solid waste can provide necessary nutrient components for crops, and can effectively relieve the problems of soil hardening and the like; therefore, the composting treatment of the organic solid waste to prepare the organic fertilizer is an effective way for realizing the reduction, reclamation and harmlessness of the biomass waste.
Chinese patent document CN 101973795B (application No. 201010514582.7) discloses a method for aerobic composting of sludge by using a composting composite bacterial agent, which comprises the steps of firstly carrying out enlarged culture and domestication on bacterial liquid to obtain composite bacterial agents A and B, then putting the composite bacterial agents A into dewatered sludge of a sewage plant, mixing and stacking, covering a layer of composite bacterial agent B on the surface of a pile, and continuously stacking until the temperature of the pile reaches the environmental temperature, thus completing aerobic composting of sludge.
Chinese patent document CN 103539494B (application No. 201310506314.4) discloses a bin type sludge aerobic composting method, which comprises the steps of firstly establishing a bin type sludge aerobic composting device, uniformly paving polyvinyl chloride spherical suspension on a porous cover plate in a fermentation bin, and then uniformly mixing dewatered sludge and sawdust of a sewage treatment plant and filling the mixture into the fermentation bin; the amount of aeration is then controlled to begin the composting process.
The two composting methods are that the organic solid waste is placed in a composting bin, and the composting method has the problems of uneven mixing of raw materials, insufficient oxygen supply and low oxygen utilization rate.
In addition, as an improvement, some aerobic composting devices adopt stirring paddles to mix and supply oxygen to the compost body, but the situation of material caking and uneven mixing is easy to occur in the mixing process, and the problems of insufficient oxygen supply and low oxygen utilization rate still exist.
Disclosure of Invention
The invention aims to provide an aerobic composting device and a composting method for organic solid wastes, which have uniform mixing and high oxygen supply efficiency.
The technical scheme for realizing the first purpose of the invention is that the aerobic composting device of the organic solid waste comprises a composting bin, a grate type feeding device, a screw extrusion dehydration discharging device, an oxygen supply device, a leachate circulating spraying device, an exhaust pipe and a temperature measuring device; the grate type feeding device and the screw extrusion dehydration discharging device are arranged in the composting bin, and the grate type feeding device is positioned below the screw extrusion dehydration discharging device.
The composting bin comprises a bin body, a material collecting groove, a percolate storage tank, a material inlet and outlet, a bin gate and a discharging plate, wherein the material collecting groove and the percolate storage tank are arranged at the bottom of the bin body, and the percolate storage tank is positioned below the grate type feeding device; the feed inlet and the discharge outlet are arranged on the upper part of the side wall of the bin body and are both a feed inlet and a discharge outlet of the bin body.
The grate type feeding device is a reciprocating type step grate and conveys materials from top to bottom into a material collecting groove; the grate sheets of the grate type feeding device are arranged in a step mode, the movable grate sheet at the uppermost end is positioned below the material inlet and outlet, and the movable grate sheet at the lowermost end is connected with the material collecting groove.
The screw extrusion dehydration discharging device comprises a motor, a screw, a sleeve and a discharging guide plate, wherein the screw and the sleeve are obliquely arranged and are positioned above the grate type feeding device, the bottom ends of the screw and the sleeve are positioned in the material collecting groove, and the screw drives the material in the material collecting groove to be conveyed from bottom to top when rotating.
The oxygen supply device comprises an aeration pipe and an air compressor, wherein the aeration pipe is positioned in the percolate storage tank.
The percolate circulating spray device comprises a percolate discharging pipe, a circulating pump, a return pipe, a discharging pipe and a spray head, wherein a liquid inlet port of the percolate discharging pipe is communicated with a liquid outlet of the percolate storage tank, and the spray head is positioned above the uppermost grate segment of the grate type feeding device; the percolate discharge pipe, the circulating pump, the backflow pipe and the spray header are connected in sequence.
The peripheral surface of the bin body is provided with a heat preservation layer.
The exhaust pipe is arranged at the top end of the bin body, and the temperature measuring device is horizontally arranged on the side wall of the bin body.
The discharging plate is arranged below the material inlet and outlet, the discharging plate is rotatably connected with the bin body, the discharging plate is propped open to be connected with a discharging guide plate of the screw extrusion dehydration discharging device to form an inclined plane when discharging, and the discharging plate is placed on the bin body in the feeding and composting processes.
Further, one end of a discharging guide plate of the screw extrusion dehydration discharging device is rotatably connected below a top port of the sleeve, the end of the discharging guide plate is called a connecting end, and the other end of the discharging guide plate is called a free end; the free end of the discharging guide plate is positioned above the grate sheet at the uppermost end of the grate type feeding device, and the material output from the screw extrusion dehydration discharging device falls on the grate type feeding device; or the free end is connected with the discharging plate below the material inlet and outlet to form an inclined plane, and the material output from the screw extrusion dehydration discharging device is output from the bin body to carry out discharging operation.
And small water filtering holes are formed in the wall of a sleeve of the screw extrusion dehydration discharging device, the aperture is 3-5 mm, and the distance between adjacent holes is 20 mm.
The technical scheme for realizing the second purpose of the invention is that the method for carrying out aerobic composting by the aerobic composting device for the organic solid waste comprises the following steps:
opening a bin door of the compost bin, and starting a grate type feeding device and a screw extrusion dehydration discharging device; and (3) introducing the organic solid waste to be treated into the bin body, allowing the introduced materials to fall on the grate segment at the uppermost end of the grate type feeding device, enabling the grate segments to reciprocate, conveying the materials to the material collecting tank along the grate segments at all layers from top to bottom, and closing the bin door after the feeding of the organic solid waste to be treated is finished.
And secondly, conveying the materials in the material collecting groove from bottom to top by a screw of the screw extrusion dehydration discharging device, dehydrating the materials in the sleeve under the rotary extrusion of the screw, leaching the removed water in the materials above the grate type feeding device below the sleeve by flowing out of the sleeve, reserving a part of water in the materials, and collecting the rest water in a percolate storage tank.
The materials in the sleeve flow out from the top end of the sleeve, and the materials flowing out from the sleeve fall on the grate plates at the uppermost end of the grate type feeding device in the composting process.
And thirdly, repeating the steps of the first step and the second step in the composting process, wherein the grate type feeding device enables materials to be fed layer by layer from top to bottom, the screw extrusion dehydration discharging device conveys the materials in the material collecting groove from bottom to top, and the materials reciprocate from top to bottom and from bottom to top.
Fourthly, after a day, the composting is finished, and the unloading operation is carried out.
When a first batch of organic solid waste is treated, firstly, water or percolate of the organic solid waste is input into the bin body before feeding the first batch of organic solid waste into the bin body, and the liquid is collected in a percolate storage tank; and (4) reserving percolate in the percolate storage tank after the previous batch of organic solid waste is composted.
Opening an oxygen supply device and a leachate circulating spraying device in the step I; spraying liquid on the material by a spray head of the leachate circulating spray device; and step two, the oxygen supply device performs sufficient aeration and oxygenation on the percolate.
The process of feeding materials on the grate type feeding device from top to bottom and the process of conveying the materials in the material collecting groove from bottom to top by the screw extrusion dehydration discharging device each time take 30-60 minutes.
The invention has the positive effects that: (1) the aerobic composting device adopts a structure of combining the grate type feeding device and the screw extrusion dehydration discharging device, the grate type feeding device enables materials to be fed in a progressive manner from top to bottom, the materials can be overturned, dispersed and mixed in the feeding process, the large-area caking condition cannot occur in the mixing process, and the materials and oxygen have larger contact area; the screw extrusion dehydration discharging device conveys the materials in the material collecting groove from bottom to top, and the materials are further uniformly mixed and dehydrated under the action of the rotating screw; therefore, the combination of layer-by-layer feeding and screw dehydration discharging plays a role in high efficiency and good turning, so that the materials are fully mixed uniformly and loosened, the combination of oxygen in the air and the substrate is accelerated by loosening the materials, and the oxygen supply efficiency is improved.
(2) The material of following screw extrusion dehydration discharging device output has the play department under two kinds of circumstances, and firstly the compost is ended the back material and is exported from the business turn over material mouth in the storehouse body, and the dehydration function of device makes ejection of compact moisture content lower, and screw rod ejection of compact mode makes the material discharge from the export fast.
Secondly, the materials fall on the grate plate at the uppermost end of the grate type feeding device again in the composting process, and the composting process is continuously carried out in the bin body.
The screw extrusion dehydration discharging device is positioned above the grate type feeding device, and leachate generated after dehydration is firstly leached on materials on the grate type feeding device and then falls down to be concentrated in a leachate storage tank at the bottom of the bin body. The leachate contains a large amount of beneficial aerobic strains, and the leaching process enables the aerobic strains to be fully contacted with the material to be treated, so that a good inoculation effect is achieved; the leaching process also ensures the water content and oxygen content of the material.
(3) After the last compost, the filtration liquid in the filtration liquid holding tank of compost storehouse bottom remains, sprays the moisture content in order to adjust the new material in the new material, in addition because filtration liquid contains a large amount of bacterials, plays the inoculation effect to the new material, accelerates the compost process of later stage feeding greatly.
The percolate in the percolate storage tank is communicated with an aeration pipe to fully aerate and oxygenate the percolate, so that the percolate contains more sufficient oxygen content and the aerobic digestion of the percolate is promoted; in addition, when part of percolate containing sufficient oxygen is conveyed to the feed inlet and sprayed on the material, the oxygen content in the material is also increased.
(4) The device and the method can degrade kitchen waste, sludge of municipal sewage treatment plants, straws, landscaping garbage and the like into solid organic fertilizer for soil improvement.
Drawings
FIG. 1 is a schematic structural view of an aerobic composting apparatus according to the invention;
FIG. 2 is a schematic structural view of the device in FIG. 1 during discharging after composting is finished;
the reference numbers in the above figures are as follows: the composting bin comprises a composting bin 1, a bin body 10, a material collecting groove 11, a percolate storage tank 12, a material inlet and outlet 13, a bin gate 14 and a discharging plate 15;
a grate type feeding device 2, a grate segment 21;
the screw extrusion dehydration discharging device 3, the motor 31, the screw 32, the sleeve 33 and the discharging guide plate 34;
an oxygen supply device 4, an aeration pipe 41, and an air compressor 42;
a percolate circulating spray device 5, a percolate discharge pipe 51, a circulating pump 52, a return pipe 53, a discharge pipe 54 and a spray header 55;
an exhaust pipe 6;
and a temperature measuring device 7.
Detailed Description
(example 1)
Referring to fig. 1, the aerobic composting device for organic solid waste of the present embodiment includes a composting bin 1, a grate type feeding device 2, a screw extrusion dehydration discharging device 3, an oxygen supply device 4, a leachate circulation spraying device 5, an exhaust pipe 6 and a temperature measuring device 7; the grate type feeding device 2 and the screw extrusion dehydration discharging device 3 are arranged inside the composting bin 1, and the grate type feeding device 2 is positioned below the screw extrusion dehydration discharging device 3.
The compost bin 1 comprises a bin body 10, a material collecting groove 11, a percolate storage tank 12, a material inlet and outlet 13, a bin gate 14 and a discharging plate 15. The outer peripheral surface of the bin body is provided with a heat insulation layer, for example, covered by a layer of heat insulation material. The material collecting groove 11 and the percolate storage groove 12 are arranged at the bottom of the bin body 10, the cross section of the material collecting groove 11 is arc-shaped, and the material collecting groove 11 and the percolate storage groove 12 share one part of groove wall. The percolate storage tank 12 is located below the grate-type feeding device 2.
The material inlet and outlet 13 is arranged on the upper part of the side wall of the bin body 10, and the material inlet and outlet 13 is a material inlet of the bin body 10 and a material outlet of the bin body 10. A bin door 14 is arranged above the material inlet and outlet 13, and when the bin door 14 is closed, the interior of the bin body 10 is a closed space. A discharging plate 15 for discharging is arranged below the material inlet and outlet 13, the discharging plate 15 is rotatably connected with the bin body 10, the plate is spread (in the drawing, in a spreading state) during discharging, and the plate is placed on the bin body 10 in the feeding and composting processes.
The grate type feeding device 2 is a reciprocating type ladder grate and conveys materials from top to bottom into a material collecting groove 11; comprises a frame (not shown in the figure) and a fire grate segment; the fire grate pieces 21 are arranged in a step mode and comprise a group of fixed fire grate pieces and a group of movable fire grate pieces, the movable fire grate pieces 21 at the uppermost end are positioned below the material inlet and outlet 13, and the movable fire grate pieces 21 at the lowermost end are connected with the material collecting groove 11.
The screw extrusion dehydration discharging device 3 comprises a motor 31, a screw 32, a sleeve 33 and a discharging guide plate 34. The motor 31 is arranged outside the bin body 10, and the screw 32, the sleeve 33 and the discharging guide plate 34 are arranged inside the bin body 10. The screw 32 and the sleeve 33 are obliquely arranged and are positioned above the grate-type feeding device 2.
The motor shaft of the motor 31 is coupled to a screw 32 through a coupling, and the screw 32 is located at the center inside a sleeve 33. The bottom ends of the screw 32 and the sleeve 33 are positioned in the material collecting groove 11, and the screw rotates to drive the material in the material collecting groove 11 to be conveyed from bottom to top. The wall of the sleeve 33 is provided with small water filtering holes with the aperture of 3-5 mm and the distance between adjacent holes of 20 mm.
One end of the discharge guide 34 is rotatably connected below the top port of the sleeve 33, and this end of the discharge guide 34 is called a connection end and the other end is called a free end. The free end of the discharging guide plate 34 is positioned above the grate sheet at the uppermost end of the grate type feeding device 2, the materials output from the screw extrusion dehydration discharging device 3 fall on the grate type feeding device 2, and the composting process is continued in the bin body 10; or as shown in fig. 2, the free end is connected with a discharging plate 15 below the material inlet and outlet 13 to form an inclined plane, and the material output from the screw extrusion dehydration discharging device 3 is output from the bin body 10 to perform discharging operation.
The oxygen supply apparatus 4 includes an aeration pipe 41 and an air compressor 42. The aeration pipe 41 is provided with aeration holes, most pipe bodies are positioned in the percolate storage tank 12, and a small part of pipe bodies extend out of the bin body 10 to be connected with an air outlet of the air compressor 42.
The percolate circulation and sprinkling device 5 comprises a percolate discharge pipe 51, a circulation pump 52, a return pipe 53, a discharge pipe 54 and a sprinkling head 55. The liquid inlet port of the percolate discharging pipe 51 is communicated with the liquid outlet of the percolate storing tank 12, and a valve is arranged on the percolate discharging pipe 51; the shower head 55 is located above the uppermost grate segment of the grate-type feeding device 2.
The percolate discharge pipe 51, the circulating pump 52, the return pipe 53 and the spray header 55 are sequentially connected, and percolate in the percolate storage tank 12 is conveyed to the position above the uppermost grate segment of the grate type feeding device 2. The percolate discharge pipe 51, the circulation pump 52 and the discharge pipe 54 are connected in sequence to discharge the percolate in the percolate storage tank 12. The return pipe 53 and the discharge pipe 54 share a length of piping. Valves are provided in both the return line 53 and the discharge line 54.
The exhaust pipe 6 is arranged on the top end of the bin body 10, the air inlet of the exhaust pipe 6 is connected with the air outlet on the top end of the bin body 10, and the air outlet of the exhaust pipe 6 is connected with the gas treatment device. The gas generated by the compost of the invention is mainly carbon dioxide, and is doped with a small amount of gases such as hydrogen sulfide, for example, the gas exhausted by the exhaust pipe 6 can be absorbed by activated carbon and then discharged.
The temperature measuring device 7 is horizontally arranged on the side wall of the bin body 10 and is positioned below the grate type feeding device 2. The temperature sensing end of the temperature measuring device 7 is positioned in the bin body 10.
When the aerobic composting device is used for carrying out aerobic composting on organic solid waste, the method comprises the following steps:
firstly, the bin door 14 of the compost bin 1 is opened, the percolate of water or organic solid waste is input into the bin body 10, and the liquid is collected in the percolate storage tank 12.
Starting a grate type feeding device 2, a screw extrusion dehydration discharging device 3, an oxygen supply device 4 and a leachate circulating spraying device 5; the organic solid waste with the water content of 30% +/-5% to be treated is introduced into the bin body 10 from the material inlet and outlet 13, the introduced material falls on the grate plate at the uppermost end of the grate type feeding device 2, and the spray head 55 of the percolate circulating spray device 5 sprays liquid on the material to ensure that the water content of the material is 40% -60%. The grate segments reciprocate to convey the materials into the material collecting groove 11 from top to bottom along the grate segments of each layer. After the feeding of the organic solid waste to be treated is completed, the bin gate 14 is closed.
Secondly, the screw 32 of the screw extrusion dehydration discharging device 3 conveys the materials in the material collecting groove 11 from bottom to top, the materials are dehydrated in the sleeve 33 under the rotary extrusion of the screw, the removed water flows out from the small hole on the sleeve 33 and is leached in the materials above the grate type feeding device 2 below the sleeve 33, part of the water is remained in the materials, and the rest of the water is collected in the leachate storage tank 12.
The oxygen supply device 4 fully aerates and oxygenizes the percolate, so that the percolate contains more sufficient oxygen content and the aerobic digestion of the percolate is promoted.
The material in the sleeve 33 flows out from the top end of the sleeve, and the material flowing out from the sleeve 33 falls on the grate plate at the uppermost end of the grate type feeding device 2 in the composting process.
Repeating the first step and the second step in the composting process, wherein the grate type feeding device 2 feeds materials layer by layer from top to bottom, the screw extrusion dehydration discharging device 3 conveys the materials in the material collecting groove from bottom to top, and the materials reciprocate from top to bottom and from bottom to top; the process that the materials are fed from top to bottom layer by the grate type feeding device 2 and the process that the materials in the material collecting groove are conveyed from bottom to top by the screw extrusion dehydration discharging device 3 each time take 30-60 minutes.
The temperature in the bin body 10 is controlled to be 40-45 ℃ in the composting process, if the temperature in the bin body 10 is measured to be higher than 45 ℃ by the temperature measuring device 7, the air inflow of the oxygen supply device 4 to the bin body 10 is increased, and if the temperature in the bin body 10 is lower than 40 ℃, hot air is blown into the bin body 10 by the oxygen supply device 4.
Gas generated in the composting process is discharged from the exhaust pipe 6, and is exhausted after being adsorbed by active carbon.
And fourthly, after 15 to 20 days, closing the grate type feeding device 2 after composting is finished, opening the bin gate 14, connecting the free end of the discharge guide plate 34 of the screw extrusion dehydration discharging device 3 with the discharging plate 15 below the material inlet and outlet 13 to form an inclined plane, and outputting the materials output from the screw extrusion dehydration discharging device 3 from the bin body 10 to perform discharging operation. And obtaining the solid organic fertilizer after composting, wherein the water content is 25-30%.
Fifthly, after the previous batch of organic solid waste is completely treated and emptied, the next batch of waste to be treated is input into the bin body 10. The leachate in the leachate storage tank at the bottom of the composting bin is reserved in the previous composting process and is used for spraying the moisture content of a new material in a later batch of new materials to adjust the moisture content of the new material, and in addition, because the leachate contains a large number of strains, the leachate plays a role in inoculation on the new material, so that the composting process of later-stage feeding is greatly accelerated.
If the percolate in the percolate storage tank is in excess, the valve on the discharge pipe 54 of the percolate circulation spray device 5 is opened
And (4) discharging part of percolate.