CN106495770A - A kind of efficient high-rate composting fermentation process of utilization agriculture and forestry organic waste material - Google Patents

Abstract

The invention provides a high-efficiency and rapid composting fermentation method utilizing agricultural and forestry waste. The present invention mixes garden waste and livestock and poultry manure into fermented materials with different carbon-to-nitrogen ratios for composting and fermentation. Analysis to determine if fermentation is ripe. The present invention measures the physical and chemical parameters in the decomposing process and records the changing rules of the parameters to study whether the compost is fermented and mature. Compared with other judgment standards, the method adopted in the present invention is more rapid and efficient, and lays a solid foundation for the comprehensive utilization of agricultural and forestry waste resources. Solid foundation.

Description

A high-efficiency and rapid composting fermentation method utilizing agricultural and forestry waste

technical field

The invention belongs to the technical field of comprehensive utilization of agricultural and forestry waste resources, and in particular relates to a high-efficiency and rapid composting fermentation method for utilizing agricultural and forestry waste.

Background technique

With the rapid development of my country's animal husbandry and garden planting industry, the national poultry breeding volume and garden planting area have gradually increased, and more than 20 million tons of livestock and poultry manure and a large number of dead branches and leaves are produced every year. However, these manure and dead branches and leaves If it is not handled properly, it will not only cause waste of resources, but also cause pollution of livestock and poultry breeding, land occupation, and is not conducive to urban beautification and many other problems.

In addition, solid waste such as garden waste and livestock and poultry manure contains a large amount of organic matter and nutrient resources. It is estimated that it can provide 4.7-5.5 million tons of nitrogen, 2.8-3.1 million tons of phosphorus, 5.6-5.9 million tons of potassium, and more than 600 million tons of organic matter. It also contains a large amount of trace elements, which is a valuable organic fertilizer resource. If it is properly treated and utilized, it will greatly promote my country's agricultural production.

Composting can not only make the pathogenic bacteria in the above-mentioned wastes harmless through high-temperature fermentation under the action of microorganisms, humify, stabilize and finally achieve maturity of organic matter, but also can be further processed into valuable compound fertilizers. However, under modern agricultural conditions, the traditional composting technology of livestock and poultry manure has disadvantages such as time-consuming and polluting the environment, which limits the improvement of the quality of livestock and poultry manure; there are also problems of poor composting effect due to excessive decomposition, or immature composting , C/N inappropriate and other reasons lead to the inability to make full use of manure and dead branches and leaves waste, and cannot guarantee the quality of compost.

Contents of the invention

The invention provides a high-efficiency and rapid composting fermentation method using agricultural and forestry wastes. The invention mainly uses garden wastes (dead branches and leaves) and livestock and poultry manure (chicken manure, cow manure and pig manure) to mix in different proportions, and then carry out Biological fermentation, by measuring the pH, temperature, electrical conductivity, carbon-nitrogen ratio and other indicators of compost fermentation products, it is simple, fast and efficient to determine whether the compost fermentation is mature, avoiding the more cumbersome index systems and methods that are not suitable for modern large-scale production.

In order to achieve the above-mentioned purpose of the invention, the present invention adopts the following technical solutions to achieve:

A high-efficiency and rapid composting fermentation method utilizing agricultural and forestry waste, it comprises the following steps:

(1) Selection of composting sites;

(2) Preparation of fermentation materials: Fermentation pile materials are prepared from garden waste and livestock and poultry manure according to C/N=25:1~35:1;

(3) Heap building and material pretreatment: On the composting site, excavate two cross-shaped air channels to adjust the water content of the fermentation material to 60%-65%;

(4) Fermentation: Spread dead branches on the intersection of the two air channels, spread a layer of leaves on the dead branches, and then pile up the prepared garden waste and the fermentation pile materials of livestock and poultry manure in order for fermentation;

(5) During the fermentation process, adjust the water content of the fermentation heap to keep it at 50%-60%. After more than 30 days of fermentation, the compost has no odor and the product is in the form of loose dark brown pellets; the measured pH is 5.5-8.0; The C/N in the heap is less than 20; the EC value of the compost extract is less than 8ms/cm, judging that the fermentation is complete.

Further: the selection criteria for the composting site in the step (1) are: facing the sun against the wind, close to the water source, convenient for the transportation of composting materials, and the ground of the selected site is flat or shallow.

Further: the livestock and poultry manure in the step (2) includes chicken manure, cow manure and pig manure, and the garden waste includes crushed leaves and branches.

Further: the depth and width of the cross-shaped groove in the step (3) are both 20 cm.

Further: In the step (4), the hard dead branches are covered at the intersection of the two air channels, and wooden sticks are placed perpendicular to the ground at the center of the intersection of the two small channels, and then each of the two air channels Spread a layer of sludge or fine soil as a bottom pad to absorb infiltrated fertilizer; spread a layer of leaves evenly on the dead branches, and then place a layer of crushed dead branches and leaves and a layer of manure, and the dead branches and leaves The pulverized matter and feces are piled up alternately, with four layers for each of the two raw materials, and each raw material is stacked sequentially from the first layer to the fourth layer according to the weight ratio of 1:2:3:4.

Further: In the step (5), the thermometer is inserted 20-25 cm below the reactor surface from three different directions, and the temperature of the reactor body is regularly monitored at 9 o'clock every morning.

Further: in the step (2), pig manure and dead branches and leaves are optimal fermentation piles according to C/N=25/1.

Further: 30d-45d of fermentation in the step (5).

Further: when the fermentation in step (5) is completed, the water-soluble organic carbon content is <1.7%.

Further: During the composting period in the step (5), turn the compost once every 5 days.

Compared with the prior art, the advantages and technical effects of the present invention are: the present invention provides a method of composting by mixing different raw materials (chicken manure, cow manure and pig manure) with garden waste (dead branches and leaves) in different proportions Method of fermentation. The fermentation method of the present invention is divided into two steps, firstly, composting fermentation, comprises the selection of stacking place, the modulation of stacking ingredients, building pile and fermenting; Secondly, during composting, carry out turning once every 5 days, take a sample and carry out index measurement, And adjust the water content according to the measured water content percentage. The measurement indicators include reactor temperature and the water content, pH, total carbon content, total nitrogen content, effective P content, available K content, EC value and its cellulose, hemicellulose, lignin content, water soluble organic carbon, nitrate nitrogen, and ammonium nitrogen. By measuring the physical and chemical parameters in the decomposing process and recording the changing rules of the parameters, it is possible to study whether the compost is fermented or not. Compared with other judgment standards, the method adopted in the present invention is faster and more efficient, and lays a solid foundation for the comprehensive utilization of agricultural and forestry waste resources. .

Description of drawings

Fig. 1 is the trend of temperature change in the fermentation pile of the present invention;

Fig. 2 is the variation trend of water content in the fermentation pile of the present invention;

Fig. 3 is the change trend of pH in the fermentation pile of the present invention;

Fig. 4 is the change trend of total carbon content in the fermentation pile of the present invention;

Fig. 5 is the change trend of total nitrogen content in the fermentation pile of the present invention;

Fig. 6 is the change trend of available phosphorus content in the fermentation pile of the present invention;

Fig. 7 is the trend of change of available potassium in the fermentation pile of the present invention;

Fig. 8 is the change trend of electrical conductivity in the fermentation pile of the present invention;

Fig. 9 is the variation trend of cellulose content in the fermentation heap of the present invention;

Fig. 10 is the change trend of hemicellulose content in the fermentation heap of the present invention;

Fig. 11 is the variation trend of lignin content in the fermentation pile of the present invention;

Fig. 12 is the degradation rate of cellulose, hemicellulose, and lignin in the fermentation pile of the present invention;

Fig. 13 is the changing trend of water-soluble organic carbon content in the fermentation pile of the present invention;

Fig. 14 is the change trend of ammonium nitrogen in the fermentation pile of the present invention;

Fig. 15 is the change trend of nitrate nitrogen content in the fermentation heap of the present invention;

Fig. 16 is the change trend of carbon-nitrogen ratio in the fermentation pile of the present invention.

detailed description

The technical solutions of the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example 1

The efficient and fast composting fermentation method utilizing agricultural and forestry waste of the present invention comprises the following steps:

1. Compost fermentation

1. Selection of stacking site

It is leeward to the sun and close to the water source, which is convenient for the transportation of compost materials. After the stacking site is selected, the ground should be leveled or shallow pit.

2. Modulation of stacking ingredients

The first pile: mixture of chicken manure and dead branches and leaves, C/N=25:1;

The second pile: a mixture of cow dung and dead branches and leaves, C/N=25:1;

The third pile: a mixture of cow dung and dead branches and leaves, C/N=30:1;

The fourth pile: a mixture of pig manure and dead branches and leaves, C/N=30:1;

The fifth pile: a mixture of cow dung and dead branches and leaves, C/N=35:1;

The sixth pile: mixture of chicken manure and dead branches and leaves, C/N=30:1;

The seventh pile: a mixture of pig manure and dead branches and leaves, C/N=25:1.

, build up and ferment

3.1 The design of the stacking site and the pretreatment of raw materials

On the ground that has been leveled and compacted, excavate a "ten"-shaped ditch as a ventilation ditch for the fermentation pile, with a depth of 20 cm and a width of 20 cm (measured with a meter ruler, it must be accurate). According to the water content percentage of the fermentation raw material, the moisture content of the fermentation raw material (crushed leaves of dead branches, chicken manure, pig manure and cow manure) is adjusted to 65%.

3.2 Implementation of the stacking method

The intersection of the "ten" gutter is covered with hard dead branches as the ventilation ditch at the bottom of the compost, and at the center of the intersection of the two small ditch, sticks are placed perpendicular to the ground as the upper and lower ventilation channels for the compost. Then spread a layer of sludge or fine soil with a thickness of 2cm in the ventilation ditch of the fermentation heap as a bottom pad for absorbing the infiltrating fertilizer. Evenly spread a layer of uncrushed leaves on the hard dead branches; then compost and ferment the prepared fermentation materials, and place the crushed dead branches and leaves on the first layer of the fermentation pile to make the bottom area as large as possible Some, spread out in a circle, and place feces on the second layer. The crushed dead branches and leaves and the feces are stacked in an alternate and repeated order of eight layers. The two raw materials (crushed dead branches and leaves and feces) are respectively four layers, and Each raw material is stacked sequentially from the first layer to the fourth layer according to the weight ratio of 1:2:3:4, and finally piled up into a fermentation pile with a weight of 180 kg.

Second, the determination of various indicators of raw materials

Use the five-point sampling method to sample from the fermentation heap, that is: first determine the midpoint of the diagonal as the central sampling point, and then select four points on the diagonal that are equal to the distance from the central sampling point as the sampling point. And samples were taken after composting on the 0th, 5th, 10th, 15th, 20th, 25th, 30th, 35th, 40th, and 45th day of composting fermentation.

Fermentation pile temperature monitoring

Insert thermometers 25-30cm below the surface of the reactor from three different directions, and monitor the temperature of the reactor in real time at 9 o'clock every morning.

It can be seen from Figure 1 that the temperature change of the pile body is divided into three stages, namely, the heating stage, the high temperature stage and the cooling stage. In the heating stage, the organic matter is gradually degraded under the action of microorganisms, releasing a large amount of heat, which gradually increases the temperature of the pile. When the temperature gradually rises to 55°C, the pile enters a high temperature period. In the high temperature period, the pile continues to kill germs at high temperature, and at this stage the microorganisms gradually degrade the remaining organic matter in the pile. When the organic matter in it is gradually degraded and exhausted, the pile body enters the cooling period (the temperature is lower than 50°C), and when the temperature of the pile body drops to the ambient temperature, the pile body is basically decomposed.

Determination of moisture content

Take the sample to be tested with an initial weight of 15.000g and place it in an oven at 105°C for 24h to dry until constant weight (the error of the two measurements is within 0.05g), and measure the moisture content.

It can be seen from Figure 2 that the water content of each fermentation pile begins to drop sharply on the fifth day, and then rises slowly after several days. The water content is preferably 50%-60%, so the water content is adjusted every five days. Excessive moisture will reduce free porosity, affect air diffusion, easily cause anaerobic state, and cause leachate treatment problems; moisture below 40%, microbial activity will decrease, and compost temperature will drop accordingly.

Determination of pH

The samples were air-dried or placed in a drying oven at 35-40°C for drying treatment, and then crushed through a 10-mesh (2 mm) sieve. Take 5g of the dried and pulverized sample into a sample bottle, add 50ml of distilled water, vibrate on a shaker at 180rpm for 60min, and let it stand for 1-3h. During the standstill, air should not enter the sample bottle; measure the pH after calibrating the pH meter .

It can be seen from Figure 3 that the pH of the 7 groups of fermentation piles is between 6.0-8.5 from the initial stage of fermentation to the end of decomposing. Due to different raw materials, the pH change trend in the fermentation process is not the same, but they all meet the national decomposing requirements (5.5-8.5).

Determination of total carbon content

The specific steps for the determination of total carbon are as follows: take 2.000g and put it into a crucible with constant weight, place the crucible in a muffle furnace and heat it up to 600°C, and ash it for 15 minutes; transfer the crucible to a desiccator to cool and weigh it; The difference in weight is the weight of the volatile solids (VS).

The estimation formula of total carbon=0.47VS, VS=(a-b)/(a-c), a is the weight of the sample plus the crucible; b is the weight of the sample plus the crucible after ashing; c is the weight of the crucible.

It can be seen from Figure 4 that the total carbon content in the first and middle stages of the fermentation showed a downward trend as the fermentation progressed, and the total carbon content of each fermentation heap remained stable after about 30 days of fermentation. During composting, carbon sources are consumed and converted into carbon dioxide and humus substances.

Determination of total nitrogen content

1.5.1 Sample preparation

Take 1.000g (18 mesh) of pulverized and dried sample and place it in the digestion tube, and measure its moisture content at the same time. 1.5.2 Digestion of samples:

Add 10ml of concentrated sulfuric acid to the digestion tube, mix well, add 5g Na ₂ SO4 and 0.5g CuSO4, heat and digest for 4 hours, and continue to digest for 2 hours until the sample is digested to gray-green to make the ammonium salt react completely. Cool down after digestion. 1.5.3 Distillation of ammonia:

Set the program, add 50ml 35% NaOH to the digestion tube, add 50ml 1.5% boric acid to the absorption bottle, insert the end of the condenser tube 1cm below the absorption liquid, start the Kjeldahl nitrogen analyzer to distill until the distillate contains no ammonia (distillate If the liquid does not react with Nessler's reagent), stop the distillation.

1.5.4 Determination of ammonium:

Add 2~3 drops of bromocresol green-methyl red mixed indicator to the sample distillate, and titrate the distillate with the calibrated hydrochloric acid standard solution to make it change from blue-green to reddish-purple. Record the volume (mL) of hydrochloric acid used.

1.5.5 Blank test: When digesting the sample, use sucrose as the blank control, except that the sample is not added, and the other operations are the same as before. The blank test is carried out simultaneously with the sample determination, and the volume of acid required is determined. (Generally no more than 0.4mL).

It can be seen from Figure 5 that the total nitrogen content of each fermentation pile showed a trend of first decreasing and then slowly increasing, and the conversion of nitrogen was divided into three parts. The first part was lost in the form of ammonia gas, and the second part was lost through nitrification and denitrification. It is converted into nitrate and nitrite, and the third part is assimilated and absorbed by organisms such as microorganisms. Although the content of total nitrogen also decreased, it was relatively less for total carbon, so after the composting was completed, the content of total nitrogen in the compost increased relatively.

And it can be seen from Figure 16 that with the progress of the composting process, the C/N of the organic fertilizer continued to decrease. Theoretically, at the end of composting, the C/N in the heap should be about 16. It is generally believed that when the C/N of the compost product is less than 20, it can be considered to be basically mature.

Determination of available phosphorus content

1.6.1 Preparation of standard curve

Take 5 µg·mL ^-1 phosphorus standard solution 0, 1.0, 2.0, 3.0, 4.0, 5.0ml respectively in five 150ml Erlenmeyer flasks, add 10ml 0.5mol·L ^-1 NaHCO ₃ and make up to 45ml with distilled water, shake well, Then add 5ml molybdenum-antimony antimony reagent and mix to develop color. After standing for 30 minutes, measure it with an ultraviolet spectrophotometer at a wavelength of 880nm. Draw the standard curve with the concentration of phosphorus standard solution as the abscissa and the absorbance value as the ordinate.

1.6.2 Handling of samples

Weigh 2.5g (accurate to 0.001g) of crushed (20 mesh) air-dried sample into a 150ml Erlenmeyer flask, add 50ml of 0.5mol/l NaHCO ₃ solution, shake for 30min, immediately filter with phosphorus-free filter paper, and collect the filtrate.

1.6.3 Determination of available phosphorus in samples

Draw 5ml of the filtrate into a 150ml Erlenmeyer flask, add 10ml of 0.5mol/l NaHCO ₃ solution, then add 35ml of distilled water with a burette, then add 5ml of molybdenum antimony reagent with a pipette, shake well, let it stand for 30min, and then use a wavelength of 880nm Colorimetric.

It can be seen from Figure 6 that the available phosphorus content in each fermentation heap showed a trend of decreasing first and then increasing. The available phosphorus indicates the fertility of the organic fertilizer to a certain extent. The available phosphorus content in the organic fertilizer is maintained at a high level, and the microbial activity and quantity in the compost can be maintained at a high level. The available phosphorus content of the No. 7 pile can be seen from the figure much higher than the rest.

Determination of available potassium

1.7.1 Reagent preparation

Extractant (1mol/L ammonium acetate, PH=7.0): Weigh 77.10g of ammonium acetate (NH ₄ OAc analytical grade) and dilute with water, and dilute to nearly 1L. (If the pH is not at 7.0, adjust to 7.0 with dilute acetic acid or dilute ammonium hydroxide, and finally dilute to 1L with water).

Potassium standard solution: Dissolve 0.1907g potassium chloride (analytical grade, dry at 110°C for 2 hours) in 1mol/L ammonium acetate solution, and dilute to 1L with 1mol/L ammonium acetate solution. It is the standard solution containing 100µɡ·mL ^-1 potassium. Take 0, 2.5mL, 5.0mL, 10.0mL, 15.0mL, 20.0mL, 40.0mL of this potassium standard solution into a 100mL volumetric flask, and dilute with 1mol/L ammonium acetate solution to obtain 0, 2.5, 5.0, 10.0, 15.0 , 20.0, 40.0µɡ·mL ^-1 potassium standard solutions with different concentrations.

1.7.2 Preparation of standard curve

Configure 0, 2.5, 5.0, 10.0, 15.0, 20.0, 40.0µɡ·mL ^-1 potassium standard solutions with different concentrations, use 0µɡ·mL ^-potassium standard solution to adjust the flow detection reading on the flame photometer to zero, and then measure the potassium standards of each concentration For the galvanometer reading of the solution, draw a standard curve on graph paper with the potassium solution concentration as the abscissa and the galvanometer reading as the ordinate.

1.7.3 Determination of available potassium content in samples

Weigh 0.5g of crushed (2mm) air-dried sample into an extraction bottle, add 50mL of 1mol/L ammonium acetate solution, stopper and shake for 30min, then filter with filter paper, and collect the filtrate. Take the filtrate and measure its potassium content with a flame photometer, and record the current readings.

Available potassium (mg/kg, K) = test solution (µɡ mL ^-1 ) × v/m

The number of potassium µɡ·mL ^-1 found ------- Find the corresponding potassium ppm number from the standard curve.

v ------- Add the number of mL of extractant.

m ------- dry weight of the sample (g).

It can be seen from Figure 7 that the content of available potassium in each fermentation heap remained stable at first, then dropped sharply during 25-30 days, and remained stable after 30 days. Microorganisms mainly use available potassium in the compost. If the content of available potassium is maintained at a high level, the number and activity of microorganisms can be maintained at a high level. The figure shows that the content of available potassium in the No. 7 pile is slightly higher than that of other piles.

Determination of value

Take the pulverized sample and add it to the Erlenmeyer flask, and add deionized water according to the solid-to-liquid ratio of 20% (w/v), seal and shake for 3 minutes, then centrifuge at 4000rpm for 10 minutes to get the supernatant, and measure its EC value with a conductivity meter.

It can be seen from Figure 8 that the conductivity in each fermentation pile showed a downward trend and remained stable for about 25 days. Conductivity reflects the total concentration of ions in the compost leach solution, that is, the content of soluble salts. Within a certain concentration range, the salt content of the solution is positively correlated with the electrical conductivity (EC). Soluble salt in compost is one of the important factors that cause toxicity to crops, and it is mainly composed of organic acid salts and inorganic salts. When the EC value is less than 8.0ms/cm, there is no inhibition on plant growth. It can be seen from the figure that the EC values of the 7 groups of fermentation piles are all below 8.0ms/cm, so the influence of salt damage is excluded.

Determination of cellulose, hemicellulose and lignin content

The determination of cellulose, hemicellulose and lignin content refers to "Wang Jinzhu, Wang Yuanxiu, Li Feng et al. Determination of cellulose, hemicellulose and lignin in corn straw [J]. Shandong Food Fermentation, 2010, (03)" literature method.

It can be seen from Figure 9-Figure 12 that the contents of cellulose, hemicellulose, and lignin in the fermentation piles of each group gradually decreased with the prolongation of fermentation time, and the degradation rate diagram showed that the cellulose, hemicellulose, and lignin in the seventh pile were fermented to 45 days. Cellulose and lignin are most degraded, so they can be used as the basis for evaluating which group of fermentation piles is more suitable for compost fermentation.

Determination of Water Soluble Organic Carbon (WSOC)

1.10.1 Preparation of standard curve

Take 0, 0.1, 0.5, 1.0, 1.5, 2.0, 2.5ml from the oxalic acid solution with a concentration of 100mg/L in a 10ml test tube, add water to make up to 5ml, then add 2.5mL of 10mmol/L Mn(III)-pyrophosphoric acid and 2.5mL concentrated H ₂ SO ₄ , shake well, let it stand for 1h, and compare the color at 490 or 500nm.

1.10.2 Determination of samples

The sample was mixed according to the ratio of water and sample at 5:1, shaken at 200r/min for 2h, centrifuged at 12500r/min for 20min, filtered, and the filtrate was taken to measure the WSOC value.

The determination method is as follows: In a 10mL test tube, add 0~5mL of the test solution (to make the organic carbon content 0~25mg), if it is less than 5mL, add water to 5mL, and then add 2.5mL of 10mmol/L Mn(III)-pyrophosphoric acid And 2.5mL concentrated H ₂ SO ₄ , shake well, let it stand for 1h, and compare the color at 490 or 500nm.

It can be seen from Figure 13 that the content of water-soluble organic carbon in the fermenters of each group showed a downward trend, and the rate of decline tended to be gentle at about 30 days. In the composting process, microorganisms preferentially use water-soluble organic matter. When water-soluble organic matter is insufficient to meet the needs of microbial growth, reproduction and metabolism, microorganisms are more difficult to degrade and refractory organic matter is in a water-soluble state, and then fully utilized. Therefore, water-soluble organic matter in organic fertilizers The content has a certain guiding significance for the evaluation of decomposing degree. Among the water-soluble indicators, water-soluble organic carbon is widely used, but the specific standard of water-soluble organic carbon has not yet been determined. Generally, the water-soluble organic carbon content <1.7% is used as an index to evaluate the maturity of compost.

Determination of ammonium nitrogen

1.11.1 Preparation of standard curve

Take 1.0ml of the NH ₄ ⁺ -N standard solution with a concentration of 0, 5.0, 10.0, 20.0, and 40.0 ppm (ug/mL) in a 25ml colorimetric tube, add KCl solution to 10.0ml, Add 4ml of alkaline phenol solution to the quantitative NH ₄ ⁺ -N solution, then add 10ml of sodium hypochlorite solution with a liquid adder, drop KCl to the scale line, shake well, after standing for 1h, use a spectrophotometer to measure color at 630nm, Read the absorbance A.

1.11.2 Determination of samples

Weigh about 2.000g of soil sample into a conical flask with an electronic analytical balance, add 40ml of KCl solution, put it on a shaker, shake for 1h, filter it into a 50ml volumetric flask, and do a blank test at the same time. Add 4ml of alkaline phenol solution to a certain amount of NH ₄ ⁺ -N solution, then add 10ml of sodium hypochlorite solution with a liquid adder, drop KCl to the scale line, shake well, after standing for 1h, use a spectrophotometer at 630nm to compare color, read the absorbance A.

It can be seen from Figure 14 that the content of ammonium nitrogen in each fermentation heap showed a downward trend and remained stable for about 30 days. In the early stage of composting, a large amount of nitrogen in the heap volatilized in the form of ammonium nitrogen. The content of ammonium nitrogen in the heap is less than 0.04% as the standard of compost maturity.

Determination of nitrate nitrogen

1.12.1 Preparation of standard curve

Absorb nitrate nitrogen standard stock solution 0, 0.50, 1.00, 1.50, 2.00, 2.50 ml into six 50 ml volumetric flasks respectively, dilute to volume with pure water, and mix well. The concentrations are 0, 1.00, 2.00, 3.00, 4.00, 5.00 mg/L, respectively. Use a 1 cm quartz cuvette to measure the absorbance at the wavelengths of 220 nm and 275 nm, calculate △A (△A=A220-A275), and draw the standard curve of nitrate nitrogen concentration.

1.12.2 Determination of samples

For 5 grams of sample, add 100 milliliters of 2 moles per liter of potassium chloride solution, extract in an ultrasonic generator for 20 minutes, take it out and set the volume to 200 milliliters, vacuum filter to remove residue, and add 1 gram of Activated carbon adsorption for 6 hours. Activated carbon was removed by suction filtration to obtain a clear liquid, and the color was compared at wavelengths of 225 and 275 nanometers to calculate the ΔA value, and the concentration was calculated using the ΔA standard curve.

It can be seen from Figure 15 that the nitrate nitrogen content in each fermentation heap showed an upward trend and tended to level off at about 30 days. In the later stage of composting, nitrification is more likely to occur in the compost, which gradually increases the content of nitrate nitrogen in the compost. NH ₄ -N/NO ₃ -N< 0.16 is regarded as a symbol of compost maturity.

Summary by above analysis result can know that: the present invention utilizes the judging standard of the decomposing degree of the high-efficiency and fast composting fermentation of agricultural and forestry waste as follows:

(1) The temperature change is divided into three stages, namely, the heating stage, the high temperature stage and the cooling stage. When the temperature gradually rises to 55°C, the pile body enters a high temperature period. In the high temperature period, the pile continues to kill germs at high temperature, and at this stage the microorganisms gradually degrade the remaining organic matter in the pile. When the organic matter in it is gradually degraded and exhausted, the pile body enters the cooling period (the temperature is lower than 50°C), and when the temperature of the pile body drops to the ambient temperature, the pile body is basically decomposed.

(2) Control of water content, preferably 50%-60% water content, too much water will reduce free porosity, affect air diffusion, easily cause anaerobic state, and cause leachate treatment problems at the same time; water content is lower than 40% , the microbial activity decreased, and the compost temperature decreased accordingly.

(3) Changes in pH. When the compost is too acidic (<6) or too alkaline (>9), the growth environment is not suitable for the growth and reproduction of microorganisms. Therefore, in the composting process of organic fertilizers, composting is suitable The pH range is 6.7-9.0, and the optimum range is 5.5-8.0.

(4) Total carbon, total nitrogen, and C/N. As composting proceeds, carbon is gradually converted into carbon dioxide and macromolecular organic matter (such as humus, etc.), resulting in a gradual decrease in the total carbon content in the compost. Although the content of total nitrogen also decreased, it was relatively less for total carbon, so after the composting was completed, the content of total nitrogen in the compost increased relatively. Therefore, as the composting process proceeds, the C/N of the organic fertilizer continues to decrease. Theoretically, at the end of composting, the C/N in the heap should be about 16. It is generally believed that when the C/N of the compost product is less than 20, it can be considered to be basically mature.

(5) EC value, which reflects the total concentration of ions in the compost extract, that is, the content of soluble salts. Within a certain concentration range, the salt content in the solution is positively correlated with the conductivity. It has been proved by experiments that when the concentration of salt ions in the compost leach solution is higher than 8ms/cm, too high salt content will inhibit the growth of microorganisms and the growth and metabolism of organic matter.

(6) Water-soluble organic carbon. During the composting process, microorganisms preferentially utilize water-soluble organic matter. Among water-soluble indicators, water-soluble organic carbon is widely used. However, the specific standard of water-soluble organic carbon has not yet been determined. Generally, water-soluble organic carbon Carbon content <1.7% was used as an index to evaluate the maturity of compost.

(7) Ammonium nitrogen and nitrate nitrogen. In the early stage of composting, a large amount of nitrogen in the heap volatilizes in the form of ammonium nitrogen. In the later stage of composting, nitrification is more likely to occur in the compost, which gradually increases the content of nitrate nitrogen in the compost. The content of ammonium nitrogen in the heap is less than 0.04% as the standard of compost maturity. NH ₄ -N/NO ₃ -N< 0.16 is regarded as a sign of compost maturity.

(8) The content of available phosphorus, the content of available phosphorus in each fermentation heap showed a trend of decreasing first and then increasing. Available phosphorus indicates the fertility of organic fertilizer to a certain extent, and the content of available phosphorus reaches more than 200mg/kg, so that the microbial activity and quantity in compost can be maintained at a high level.

(9) The content of available potassium is stable at first, and then drops sharply during 25-30 days. After 30 days, the content of available potassium is ≥0.17%. Microorganisms mainly use available potassium in compost, and the content of available potassium is maintained at a certain level. Quantity and activity can be maintained accordingly.

(10) The content of cellulose, hemicellulose and lignin in each group of fermentation piles gradually decreased with the prolongation of fermentation time, and the degradation rate of cellulose was ≥19.18%; the degradation rate of hemicellulose was ≥19.59%; the degradation rate of lignin was ≥ 15.75%.

Based on the above analysis, and by observing the physical properties and chemical indicators of the seven piles of fermentation products, it is proved that the seventh pile is more suitable for compost fermentation.

(1) Physical properties: In the seventh pile, the temperature naturally decreases in the later stage of composting, and no longer attracts mosquitoes and flies; there is no odor; the compost product forms a loose dark brown pellet. The temperature change fully conforms to the three phases, and finally approaches the external ambient temperature. The water content is not lower than 40%.

(2) Chemical indicators: at the end of composting, the pH is in the range of 5.5-8.0; the C/N in the heap is less than 20; NH ₄ -N/NO ₃ -N<0.16; the content of available phosphorus reaches 449.68mg/kg The available potassium content is 0.41%; the degradation rate of cellulose is 28.13%, the degradation rate of hemicellulose is 32.14%, and the degradation rate of lignin is 41.99%.

To sum up, the seventh pile: the mixture of pig manure and dead branches and leaves, C/N=25:1 is the pile with the most efficient and fast fermentation effect.

The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art can still understand the foregoing embodiments. Modifications are made to the technical solutions described, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions claimed in the present invention.

Claims (10)

1. an efficient and fast composting fermentation method utilizing agricultural and forestry waste, is characterized in that, it comprises the following steps: (1) Selection of composting sites; (2) Preparation of fermentation materials: Fermentation pile materials are prepared from garden waste and livestock and poultry manure according to C/N=25:1~35:1; (3) Heap building and material pretreatment: On the composting site, excavate two cross-shaped air channels to adjust the water content of the fermentation material to 60%-65%; (4) Fermentation: Spread dead branches on the intersection of the two air channels, spread a layer of leaves on the dead branches, and then pile up the prepared garden waste and the fermentation pile materials of livestock and poultry manure in order for fermentation; (5) During the fermentation process, adjust the water content of the fermentation heap to keep it at 50%-60%. After more than 30 days of fermentation, the compost has no odor and the product is in the form of loose dark brown pellets; the measured pH is 5.5-8.0; The C/N in the heap is less than 20; the EC value of the compost extract is less than 8ms/cm, judging that the fermentation is complete. 2. The efficient and fast composting fermentation method using agricultural and forestry waste according to claim 1, characterized in that: the selection criteria of the composting site in the step (1) is: leeward to the sun, close to the water source, and convenient for the transportation of composting materials , Flatten or shallow pit the selected site. 3. The high-efficiency and rapid composting fermentation method using agricultural and forestry wastes according to claim 1, characterized in that: the livestock and poultry manure in the step (2) includes chicken manure, cow manure and pig manure, and the garden waste Things include crushed leaves and branches. 4. The high-efficiency and rapid composting fermentation method using agricultural and forestry wastes according to claim 1, characterized in that: the depth and width of the cross-shaped groove in the step (3) are both 20 cm. 5. The high-efficiency and rapid composting fermentation method using agricultural and forestry wastes according to claim 1, characterized in that: in the step (4), hard dead branches are covered at the intersection of the two air channels, and At the intersection center of the small ditch, place wooden sticks perpendicular to the ground, and then spread a layer of sludge or fine soil in each of the two ventilation ditches as a bottom pad for absorbing infiltrating fertilizer; evenly spread a layer of leaves on the dead branches , and then place the pulverization of one deck of dead branches and leaves and one deck of ight soil, the pulverization of dead branches of leaves and the excrement are piled up alternately in sequence, each four layers of two kinds of raw materials, every kind of raw materials is according to 1 from the first layer to the fourth layer: The weight ratio of 2:3:4 is stacked sequentially. 6. The high-efficiency and rapid composting fermentation method using agricultural and forestry wastes according to claim 1, characterized in that: in the step (5), the thermometer is inserted at 20-25 cm below the reactor surface from three different directions, and every morning At 9 o'clock, the temperature of the pile body is regularly monitored. 7. The efficient and rapid composting fermentation method utilizing agricultural and forestry wastes according to claim 1, characterized in that: in the step (2), pig manure and dead branches and leaves are optimal fermentation piles according to C/N=25/1 . 8. The high-efficiency and rapid composting fermentation method utilizing agricultural and forestry wastes according to claim 1, characterized in that: in the step (5), fermentation takes 30d-45d. 9. The high-efficiency and rapid composting fermentation method utilizing agricultural and forestry wastes according to claim 1, characterized in that: the water-soluble organic carbon content is <1.7% when the fermentation is completed in the step (5). 10. The high-efficiency and rapid composting fermentation method utilizing agricultural and forestry wastes according to claim 1, characterized in that: during the composting period in the step (5), turn over once every 5 days.