CN110280561B

CN110280561B - Centralized landfill pit for urban domestic garbage and landfill method thereof

Info

Publication number: CN110280561B
Application number: CN201910637056.0A
Authority: CN
Inventors: 李艳; 梁嘉欣; 廖兆秋
Original assignee: China Three Gorges University CTGU
Current assignee: China Three Gorges University CTGU
Priority date: 2019-07-15
Filing date: 2019-07-15
Publication date: 2021-04-13
Anticipated expiration: 2039-07-15
Also published as: CN110280561A

Abstract

The invention discloses a centralized landfill pit for municipal solid waste and a landfill method thereof, comprising a pit body, wherein the side part and the bottom of the pit body are respectively provided with an impermeable layer, and the inside of the pit body is sequentially provided with a filter screen, an active carbon filter layer, a loam sandy soil layer, a deinking sludge layer and a sandy soil layer from bottom to top; in addition, the invention also discloses a corresponding landfill method; the invention can control the phenomenon of odor emission during the landfill of the garbage, reduce the treatment difficulty and cost of the garbage leakage liquid, reduce the landfill period and be beneficial to the collection and reutilization of the landfill garbage.

Description

Centralized landfill pit for urban domestic garbage and landfill method thereof

Technical Field

The invention relates to the technical field of domestic garbage landfill, in particular to a centralized landfill pit for urban domestic garbage and a landfill method thereof.

Background

With the rapid development of the urbanization process, a large amount of garbage waste is generated. The spam problem is listed in the foregone future crisis of world authority scientists. The life of human beings is seriously influenced by the ecological damage of a large amount of garbage and the environmental pollution. For the treatment of garbage, the main mode of garbage treatment in most countries including China at present is sanitary landfill, but because domestic garbage in China is mixed and collected, the yield of the domestic garbage is high, the water content and the organic matter content of the landfill garbage are high, and years of running experience shows that the traditional anaerobic sanitary landfill has the following outstanding problems: firstly, the leachate has high yield, high pollution load, low biodegradability, high treatment difficulty and high cost, and poses serious threats to underground water and surface water; secondly, the landfill gas production rate is low, the process is long, the collection and utilization difficulty is high, the greenhouse gas emission is increased, particularly in the field with unsmooth percolate guide and discharge, the gas guide pipeline is blocked due to percolate infiltration, and the collection and utilization rate of the landfill gas is reduced; thirdly, the land utilization efficiency is low, and the occupied area is large; fourthly, the degradation of organic matters is slow, the stabilization time of the garbage is long, and continuous supervision and maintenance are needed after the site is closed; fifthly, the landfill area has no biological covering layer, and the generated malodorous gas is directly discharged to the air, which causes serious odor pollution.

Because the landfill period of the household garbage landfill is long, the garbage corruption can emit bad smell and breed a large number of mosquitoes and flies during the landfill period; light garbage such as plastic bags in the garbage flies with wind to pollute and destroy the environment. More importantly, the rainwater penetrates the garbage and is mixed with the garbage leakage liquid, so that the treatment capacity and the treatment difficulty of the garbage leakage liquid are increased, the treatment cost is increased, the problem which is to be solved urgently in the garbage landfill is the first problem, and the necessary way for reducing the operation cost of the garbage landfill is provided.

Disclosure of Invention

The invention aims to overcome the defects and provides a centralized municipal domestic waste landfill pit and a landfill method thereof, which can control the phenomenon of odor emission during landfill, reduce the treatment difficulty and cost of waste leakage liquid, reduce the landfill period and be beneficial to collecting and recycling the landfill waste.

In order to solve the technical problems, the invention adopts the technical scheme that: the centralized landfill pit for the municipal solid waste comprises a pit body, wherein impermeable layers are arranged on the side part and the bottom part of the pit body, and a filter screen, an active carbon filter layer, a loam layer, a deinking sludge layer and a sand layer are sequentially arranged in the pit body from bottom to top.

Preferably, a liquid feeding pipe for adding a deodorizing and purifying agent is further arranged in a space enclosed by the bottom of the pit body and the filter screen, and a feeding pipe for adding a decay auxiliary agent is arranged on the pit body above the sandy soil layer.

Preferably, the bottom of the filter screen is also provided with a steel bar supporting net, the steel bar supporting net and the outer edge of the filter screen are fixed at the top of the pit body through a top plate, and two adjacent layers of the steel bar supporting net, the filter screen, the activated carbon filtering layer, the loam sandy soil layer, the deinking sludge layer and the sandy soil layer are mutually contacted.

Preferably, the top plate is provided with a sliding groove, and the sliding groove is in sliding fit with the sliding blocks at the two ends of the cover plate.

Preferably, the filter screen is made of canvas, and a silver ion sterilization layer is arranged on the upper part of the filter screen.

Preferably, the deodorizing and purifying agent comprises activated carbon, calcium oxide, magnesium oxide, aluminum oxide, copper oxide, ferrous sulfate, benzoic acid and deionized water.

Preferably, the deodorizing and purifying agent comprises the following substances in parts by mass: 30 parts of activated carbon, 26 parts of calcium oxide, 22 parts of magnesium oxide, 8 parts of aluminum oxide, 5 parts of copper oxide, 43 parts of ferrous sulfate, 28 parts of benzoic acid and 80 parts of deionized water.

Preferably, the decay aid comprises thermoactinomycetes, yeasts, filamentous fungi, trichoderma viride, azotobacter, bacillus thermophilus, bacillus subtilis, urea, an accelerator and ammonium bicarbonate.

Preferably, the decomposition auxiliary agent comprises the following raw materials in parts by mass: 13 parts of high-temperature actinomycetes, 10 parts of saccharomycetes, 16 parts of filamentous fungi, 22 parts of trichoderma viride, 33 parts of azotobacter, 5 parts of thermophilic bacillus, 13 parts of bacillus subtilis, 2 parts of urea, 15 parts of accelerant and 7 parts of ammonium bicarbonate.

In addition, the invention also discloses a landfill method of the town domestic garbage centralized landfill pit, which comprises the following steps:

step 1): digging a pit body at a refuse landfill site, and stacking the dug soil around the pit body;

step 2): paving impermeable layers on the side and the bottom of the pit body;

step 3): fixing the outer edges of the steel bar supporting net and the filter screen on the top of the pit body through a top plate, and then sequentially laying an active carbon filter layer, a loamy sand layer, a deinking sludge layer and a sand layer on the filter screen;

step 4): burying garbage to be treated in the pit body, laying a cover plate on the top of the pit body, and covering soil on the top of the cover plate to form a surface soil layer;

step 5): adding a deodorizing and purifying agent through a liquid feeding pipe to purify the liquid on the upper part of the impermeable layer; and a decay auxiliary agent is added through a feeding pipe, so that the decay of the solid garbage in the pit body is accelerated.

The invention has the beneficial effects that: according to the invention, the multilayer structure is arranged in the pit body, so that solid garbage and garbage leakage liquid can be effectively separated, in the separation process, a sand layer and a loam sand layer play a sufficient filtering role, organic matters stay in a deinking sludge layer and are decomposed, the household garbage can be quickly decomposed by adding a decomposition auxiliary agent through the feeding pipe, the decomposition efficiency is high, the problems of random stacking and uncontrolled incineration pollution of the garbage are solved, the adopted decomposition auxiliary agent is simple in preparation process, has no pollution to the environment, can also increase soil fertility and promote crop growth, and the decomposed garbage is returned to the field, so that the soil physical and chemical properties can be improved, the soil permeability is enhanced, the fertilizer consumption is reduced, the treatment difficulty and cost of the garbage leakage liquid are greatly reduced, the garbage landfill period is shortened, and the landfill garbage is favorably collected and reused; add deodorizing purifying agent through the liquid feeding pipe, can guarantee that landfill leachate produces the very first time and obtains handling to suppressed the landfill and produced more foul smell at the source, above deodorizing additive suppresses the production of foul smell voluntarily from landfill leachate's angle of treatment, in time adsorb the processing to the foul smell that produces simultaneously, guarantee the promptness of foul smell processing in the landfill, thereby improve the air quality around the landfill.

Drawings

FIG. 1 is a schematic structural view of a centralized landfill pit for municipal solid waste;

FIG. 2 is a schematic view of the structure of FIG. 1 with the cover removed;

FIG. 3 is a schematic structural diagram of a cover plate;

in the figure, 1, a top plate; 2. a liquid feeding pipe; 3. an impermeable layer; 4. a pit body; 5. a sandy soil layer; 6. a reinforcing steel bar supporting net; 7. filtering with a screen; 8. an activated carbon filter layer; 9. a sandy loam layer; 10. deinking the sludge blanket; 11. a feed tube; 12. a slider; 13. a cover plate; 14. a chute.

Detailed Description

The invention is described in further detail below with reference to the figures and specific embodiments.

As shown in figures 1 to 3, the town domestic garbage centralized landfill pit comprises a pit body 4, impermeable layers 3 are arranged on the side part and the bottom part of the pit body 4, and a filter screen 7, an activated carbon filter layer 8, a loamy sandy soil layer 9, a deinked sludge layer 10 and a sandy soil layer 5 are sequentially arranged in the pit body 4 from bottom to top. In this embodiment, the impermeable layer 3 is a waterproof breathable particle layer, and the waterproof breathable particle layer is formed by laying waterproof breathable particles, the waterproof breathable particles include aggregate and hydrophobic substance coating the aggregate, and the aggregate is preferably one or more of quartz sand, slag, ceramsite or glass beads; the waterproof breathable sand is used as a main anti-seepage material, has a waterproof breathable function, is low in water permeability or even impermeable, solves the problem of toxic gas generated by garbage sealing, and can prevent percolate from polluting soil and underground water; the impermeable material is a flexible material, so that cracks cannot be generated under the action of stratum shearing force, and the impermeable effect can be effectively maintained; in addition, the waterproof breathable sand has the characteristics of acid resistance and alkali resistance, has long service life, and can flexibly adjust the service life according to the thickness of the impermeable layer; the waterproof breathable sand is an energy-saving and environment-friendly material, can be recycled, and avoids the defects of the conventional impermeable material; in addition, the problem of landfill seepage prevention is solved by utilizing the aeolian sand in the desert, the effect of turning harm into benefit of the aeolian sand is realized, and waste is changed into valuable.

Preferably, a liquid feeding pipe 2 for adding a deodorizing and purifying agent is further arranged in a space enclosed by the bottom of the pit body 4 and the filter screen 7, and a feeding pipe 11 for adding a decay auxiliary agent is arranged on the pit body 4 above the sandy soil layer 5.

Preferably, the bottom of the filter screen 7 is also provided with a steel bar supporting net 6, the outer edges of the steel bar supporting net 6 and the filter screen 7 are fixed on the top of the pit body 4 through a top plate 1, and two adjacent layers of the steel bar supporting net 6, the filter screen 7, an active carbon filter layer 8, a loam sandy soil layer 9, a deinking sludge layer 10 and a sandy soil layer 5 are in mutual contact. In the embodiment, the sandy soil layer 5 is a capillary destruction layer and has the thickness of 0.8m, the deinking sludge layer 10 is a capillary holding water layer and has the thickness of 0.6m, and the pores of the capillary destruction layer are larger than the capillary holding water layer; the three-layer structure of the sandy soil layer 5, the deinking sludge layer 10 and the loamy sandy soil layer 9 with the thickness of 0.6m forms a capillary barrier layer, and the capillary barrier layer can keep moisture in the infiltration period and release moisture in the transpiration period. The deinking sludge layer 10 is deinking sludge generated in the process of recycling waste paper for deinking treatment, and the content of organic matters in the deinking sludge is about 60 percent, so that the propagation and decomposition of microorganisms can be promoted, and the decomposition efficiency of the microorganisms can be improved; cover deinking sludge blanket 10 from top to bottom by sand layer 5 and loamy sand layer 9 in this application, when the infiltration liquid infiltration appears in the rubbish corruption, play abundant filtering action by sand layer 5 and loamy sand layer 9, and the organic matter stops in deinking sludge blanket, when pit body upper portion rubbish is less, the moisture can appear volatilizing in the liquid that is located pit body bottom, loamy sand layer 9 can play deodorant effect this moment, because the loose degree of sand layer 5 will be greater than loamy sand layer 9 far away, consequently, through three layer construction, not only can play the filtering action to landfill leachate, can also utilize deinking sludge blanket 10 to promote the reproduction and the decomposition of microorganism simultaneously.

Preferably, the top plate 1 is provided with a sliding groove 14, and the sliding groove 14 is in sliding fit with the sliding blocks 12 at two ends of the cover plate 13.

Preferably, the filter screen 7 is made of canvas, and a silver ion sterilization layer is arranged on the upper part of the filter screen 7.

Preferably, the deodorizing and purifying agent comprises the following substances in parts by mass: 30 parts of activated carbon, 26 parts of calcium oxide, 22 parts of magnesium oxide, 8 parts of aluminum oxide, 5 parts of copper oxide, 43 parts of ferrous sulfate, 28 parts of benzoic acid and 80 parts of deionized water. Specifically, the deodorizing and purifying agent is prepared by the following steps: A. crushing active carbon, calcium oxide, magnesium oxide, aluminum oxide, copper oxide and other substances into powder and small particles by a mechanical method, and adding the powder and the small particles into a container in proportion; B. the deodorizing and purifying agent of the invention is obtained by adding ferrous sulfate, benzoic acid and deionized water to completely dissolve the ferrous sulfate, benzoic acid and deionized water, and the deodorizing and purifying agent effectively absorbs the substances which generate foul smell in the wastewater water body by utilizing the activated carbon adsorption technology to prevent the pollution to the atmosphere. The active carbon in the embodiment is fine carbon particles, has a large surface area, and is also provided with fine holes, namely capillaries, which have strong adsorption capacity, so that the active carbon can be fully contacted with the odor of a refuse landfill due to the large surface area of the carbon particles, and the odor is adsorbed when contacting the capillaries, thereby playing a purification role; benzoic acid is commonly used as a medicament or a preservative and has the function of inhibiting the growth of fungi, bacteria and moulds; calcium oxide, magnesium oxide, aluminium oxide and copper oxide can absorb and deodorize the landfill leachate that produces in the landfill, guarantee that landfill leachate produces the back very first time and obtain handling, thereby the source has suppressed the landfill and has produced more foul smell, go up the production of deodorant additive initiative suppression foul smell from landfill leachate's processing angle, the timely adsorption treatment of foul smell to the production simultaneously, the promptness of the foul smell processing in the landfill is guaranteed, thereby improve the air quality around the landfill.

Preferably, the decomposition auxiliary agent comprises the following raw materials in parts by mass: 13 parts of high-temperature actinomycetes, 10 parts of saccharomycetes, 16 parts of filamentous fungi, 22 parts of trichoderma viride, 33 parts of azotobacter, 5 parts of thermophilic bacillus, 13 parts of bacillus subtilis, 2 parts of urea, 15 parts of accelerant and 7 parts of ammonium bicarbonate. The preparation method of the decomposition auxiliary agent comprises the following steps: A. putting high-temperature actinomycetes, microzyme, filamentous fungi, trichoderma viride, azotobacter, thermophilic bacillus and bacillus subtilis into a reaction kettle, stirring uniformly at normal temperature, and sealing for 2 days to obtain a mixture A; B. adding urea and an accelerant into the mixture A, and then putting the mixture A into a stirrer to stir, wherein the rotating speed of the stirrer is 800 revolutions per minute, and the stirring time is 20min, so as to obtain a mixture B; C. and adding ammonium bicarbonate into the mixture B, and adjusting the pH value to 7-8, wherein the prepared decomposition auxiliary agent can quickly decompose the household garbage, has high decomposition efficiency, and solves the problems of random stacking and uncontrolled incineration pollution of the garbage. The accelerant in the embodiment is a functional assistant, is not a single substance, has the function of promoting the decomposition of microorganisms, and is prepared by mixing trace elements, vitamins, amino acids and humic acid, wherein the vitamins are 12%, the amino acids are 37% and the humic acid is 51%.

The trichoderma viride can generate a plurality of enzyme systems with biological activity, one of the strains with the highest cellulase activity is generated, and the generated cellulase has a degradation effect on crops; the yeast can survive in aerobic and anaerobic environments and belongs to facultative anaerobes, sugar is decomposed into carbon dioxide and water by the yeast under the aerobic condition, the yeast grows faster, and the sugar is decomposed into alcohol and carbon dioxide by the yeast under the anaerobic condition; thermophilic spore bacteria can not only tolerate high temperature, but also can grow and reproduce at high temperature, the thermophilic spore bacteria can oxidize ferrous iron, elemental sulfur, reduced inorganic sulfide and sulfide minerals, solid organic matters in the refuse landfill can be decomposed and corroded most quickly through the combination of the various bacteria, and the bacteria can produce and reproduce in severe environment, so that the continuity of decomposition can be ensured.

The deodorizing purifying agent provided by the invention is used for testing the deodorizing effect of the deodorizing agent, two urban refuse landfills A and two urban refuse landfills B are respectively selected, a foul gas detector with the model JC-ADT-EFF, which is produced by Qingdao poly-wound environmental protection equipment Limited, is used for detecting the concentration of foul gas, the concentration of the foul gas at the center of the landfills before the deodorizing purifying agent is added is recorded, the deodorizing purifying agent is splashed in the refuse landfills, the splashing amount is 5L/square meter, the deodorizing purifying agent is splashed, and the concentration of the foul gas at the center of the landfills is detected after standing for 6-8 hours, and the test data are recorded as follows:

serial number	Odor concentration/ppm	Odor concentration/ppm
			Landfill A	2938.7	341.1
Landfill B	2861.3	246.8

As can be seen from the above table, the concentration values of the front and the back odor are obviously reduced, the deodorizing and purifying agent can effectively remove the odor in the refuse landfill, the air quality near the refuse landfill is known to be very bad, especially the existing treatment mode of the urban domestic garbage, the air quality of the refuse treatment places including the refuse landfill, the refuse transfer station, the refuse treatment station and the like is very bad, one of the air quality is unpleasant odor, the air quality is very bad, the physical health of workers is greatly threatened, various toxic and harmful gases are mixed in the odor, if the odor cannot be deodorized, the odor can be effectively removed, the odor is reduced, the air quality is improved, and the deodorizing and purifying agent is beneficial to the physical health of the workers, meanwhile, the air quality can be effectively improved, and the atmospheric pollution is reduced.

In order to test the decomposition effect of the decomposition aid in the invention, three 100g portions of kitchen waste are respectively placed in three culture dishes, which are numbered A, B, C, wherein 50g of the decomposition aid is added in the group A, 20g of the decomposition aid is added in the group B, and no decomposition aid is added in the group C, the three groups of culture dishes are sealed and kept for 30 days, the solid concentrations in the three groups of culture dishes at the 1 st day, the 5 th day, the 10 th day, the 15 th day, the 20 th day and the 30 th day are respectively measured to predict the decomposition degree, and the data are recorded as follows:

from the above data it can be seen that:

the solid concentration in the group A and the group B is obviously faster than that in the group C along with the time lapse, which shows that the decomposition speed of the kitchen waste added with the decomposition auxiliary agent is far faster than that of the group C without the decomposition auxiliary agent, which shows that the decomposition auxiliary agent can effectively improve the decomposition speed, can quickly promote the decomposition of the household waste, has high decomposition efficiency and can solve the problem of long-term stacking of the household waste;

the landfill method for the town domestic garbage centralized landfill pit in the embodiment comprises the following steps:

step 1): digging a pit body 4 at a refuse landfill site, and piling dug soil around the pit body 4; in the embodiment, the pit body 4 has a length of 3m-3.5m, a width of 2.2m-2.6m and a depth of 2.1m-2.3 m;

step 2): paving impermeable layers 3 on the side and the bottom of the pit body 4;

step 3): fixing the outer edges of a steel bar supporting net 6 and a filter screen 7 on the top of the pit body 4 through a top plate 1, and then sequentially laying an active carbon filter layer 8, a loamy sandy soil layer 9, a deinking sludge layer 10 and a sandy soil layer 5 on the filter screen 7;

step 4): burying garbage to be treated in the pit body 4, laying a cover plate 13 on the top of the pit body 4, and covering soil on the top of the cover plate 13 to form a ground surface soil layer;

step 5): a deodorizing purifying agent is added through the liquid adding pipe 2 to purify the liquid on the upper part of the impermeable layer 3; the putrefaction auxiliary agent is added through the feed pipe 11, so that the putrefaction of the solid garbage in the pit body 4 is accelerated.

The embodiment can rapidly decompose the household garbage, has high decomposition efficiency, and solves the problems of random stacking and uncontrolled incineration pollution of the garbage; the adopted decomposition auxiliary agent has simple preparation process and no pollution to the environment, and can increase the soil fertility and promote the growth of crops, and the decomposed garbage returned to the field can improve the physical and chemical properties of the soil, enhance the soil permeability and reduce the fertilizer consumption.

The above-described embodiments are merely preferred embodiments of the present invention, and should not be construed as limiting the present invention, and features in the embodiments and examples in the present application may be arbitrarily combined with each other without conflict. The protection scope of the present invention is defined by the claims, and includes equivalents of technical features of the claims. I.e., equivalent alterations and modifications within the scope hereof, are also intended to be within the scope of the invention.

Claims

1. A landfill method of town domestic garbage centralized landfill pits comprises a pit body (4), wherein impermeable layers (3) are arranged on the side part and the bottom part of the pit body (4), and a filter screen (7), an active carbon filter layer (8), a loam sandy soil layer (9), a deinking sludge layer (10) and a sandy soil layer (5) are sequentially arranged in the pit body (4) from bottom to top; the utility model discloses a deodorant cleaning agent's liquid feeding pipe, including filter screen (7), reinforcing bar supporting net (6), loam matter sandy soil layer (9), deinking sludge blanket (10) and sand layer (5), filter screen (7) bottom still is equipped with reinforcing bar supporting net (6), and reinforcing bar supporting net (6) and filter screen (7) outer fringe are fixed in pit body (4) top through roof (1), and adjacent two-layer all contacts each other of reinforcing bar supporting net (6), filter screen (7), active carbon filter layer (8), loam matter sandy soil layer (9), deinking sludge blanket (10) and sand layer (5), still be equipped with liquid feeding pipe (2) that are used for adding deodorant cleaning agent in the synthetic space of pit body (4) bottom and filter screen (7), be equipped with filling tube (11) that: it comprises the following steps:

step 1): digging a pit body (4) at a refuse landfill site, and piling the dug soil around the pit body (4);

step 2): impermeable layers (3) are paved on the side parts and the bottom parts of the pit bodies (4);

step 3): fixing the reinforcing steel bar supporting net (6) and the outer edge of the filter screen (7) on the top of the pit body (4) through the top plate (1), and then sequentially paving an active carbon filter layer (8), a loam sandy soil layer (9), a deinking sludge layer (10) and a sandy soil layer (5) on the filter screen (7);

step 4): burying garbage to be treated in the pit body (4), laying a cover plate (13) on the top of the pit body (4), and covering soil on the top of the cover plate (13) to form a ground surface soil layer;

step 5): a deodorizing and purifying agent is added through the liquid adding pipe (2) to purify the liquid on the upper part of the impermeable layer (3); the putrefaction auxiliary agent is added through the feeding pipe (11), so that the putrefaction of the solid garbage in the pit body (4) is accelerated.

2. A landfill method according to claim 1, wherein: the top plate (1) is provided with a sliding groove (14), and the sliding groove (14) is in sliding fit with the sliding blocks (12) at the two ends of the cover plate (13).

3. A landfill method according to claim 1, wherein: the filter screen (7) is made of canvas, and a silver ion sterilization layer is arranged on the upper portion of the filter screen (7).

4. A landfill method according to claim 1, wherein: the deodorizing purifying agent comprises activated carbon, calcium oxide, magnesium oxide, aluminum oxide, copper oxide, ferrous sulfate, benzoic acid and deionized water.

5. A landfill method according to claim 4, wherein: the deodorizing and purifying agent comprises the following substances in parts by mass: 30 parts of activated carbon, 26 parts of calcium oxide, 22 parts of magnesium oxide, 8 parts of aluminum oxide, 5 parts of copper oxide, 43 parts of ferrous sulfate, 28 parts of benzoic acid and 80 parts of deionized water.

6. A landfill method according to claim 1, wherein: the decomposition auxiliary agent comprises high-temperature actinomycetes, microzyme, filamentous fungi, trichoderma viride, azotobacter, thermophilic bacillus, bacillus subtilis, urea, an accelerant and ammonium bicarbonate.

7. A landfill method according to claim 6, wherein: the decomposition auxiliary agent comprises the following raw materials in parts by mass: 13 parts of high-temperature actinomycetes, 10 parts of saccharomycetes, 16 parts of filamentous fungi, 22 parts of trichoderma viride, 33 parts of azotobacter, 5 parts of thermophilic bacillus, 13 parts of bacillus subtilis, 2 parts of urea, 15 parts of accelerant and 7 parts of ammonium bicarbonate.