Method for preparing biomass fuel from cow dung and recovering nitrogen and phosphorus

Abstract

The invention relates to the technical field of breeding waste disposal, in particular to a method for preparing biomass fuel and recycling nitrogen and phosphorus from cow dung. The method comprises the following steps: adding a combustible material with a certain heat value, a combustion improver and a denitration agent into solid-phase fiber excrement obtained by tempering and dehydrating cow dung and carrying out solid-liquid separation, mixing and pressing to obtain the biomass fuel. And concentrating microparticles from the separated liquid phase by adopting coagulation and centrifugation modes to complete the recovery of nitrogen and phosphorus in the liquid phase. The method for preparing the biomass fuel by taking the beef cattle manure as the main material is simple in steps, and the key point of the invention is that viscosity reduction, tempering and squeezing dehydration are carried out in two steps before the fuel is finished, so that available fibers, nitrogen and phosphorus in the beef cattle manure are respectively recycled. And then a combustible material, a combustion improver and a denitration agent are added into the dehydrated solid-phase fiber excrement, so that the prepared fuel has the advantages of high calorific value, easiness in combustion and low emission of SO2 and NOx.

Description

Technical Field

[0001] The present invention relates to the technical field of disposal of breeding waste, and particularly relates to a method for preparing biomass fuel from cow dung and recovering nitrogen and phosphorus. Background Art

[0002] The Songliao Plain in Northeast China is one of the world's three major golden corn belts. In the central part of Jilin, the northern part of Liaoning, and the eastern part of Inner Mongolia, the corn planting industry has driven the development of local livestock and poultry breeding industries, especially beef cattle breeding. A large amount of corn feed and dry straw reserves can provide low-cost food for the beef cattle in breeding. However, the problem of reusing the manure brought by beef cattle breeding is an environmental problem that urgently needs to be solved in the breeding area. Typical areas such as Horqin Left Rear Banner in Inner Mongolia have an annual beef cattle slaughter of 1.2 million heads, and Changtu County in Liaoning has an annual beef cattle slaughter of 0.4 million heads. Calculated according to the total amount of manure produced per beef cattle of 6 tons, its historical accumulation and production volume are very large. Without proper disposal plans, it will inevitably cause environmental pollution in multiple media such as water, soil, and air.

[0003] At present, the methods for reusing and disposing of beef cattle manure include making organic fertilizers, anaerobic biogas production, fuel preparation, etc. In terms of making organic fertilizers, it is mainly through aerobic composting and ripening. However, since cow dung is a cold manure, even after treatment and applied to the soil, there are still many potential hazards, such as the reduction of soil water retention performance caused by a large amount of fiber. Using cow dung to prepare biomass fuel is a method for resource utilization of livestock and poultry manure that has emerged in recent years. It mainly uses methods such as natural air drying and dehydration, and utilizes the heat of the inorganic and organic phases of cow dung to burn through a specific biomass combustion furnace. However, it is found in the process of fuel use that although the content of nitrogen and sulfur gas pollutants in the exhaust gas after combustion is lower than that of traditional fossil fuels, the problem of pollutant emissions in its exhaust gas still cannot be ignored. Especially in recent years, the increasingly serious haze phenomenon has made people pay more attention to the SO 2 and NO x emission problems.

[0004] The flue gas pollutants generated during the combustion of biomass fuel formed by natural air drying of cow dung mainly include NH 3 , HCN, NO x , HCNO, SO 2 , VOC, etc. Among them, SO 2 , NO x are two important types of pollution. At present, there are many types of technologies for preparing fuel from cow dung, focusing on improving energy utilization efficiency and the conversion rate of combustible substances. In terms of pollution control of the fuel itself, technical measures are still insufficient, manifested in: 1) Fresh cow dung contains a large amount of organic and inorganic nitrogen. The cow dung biomass fuel formed by natural air drying, dehydration, and processing into a shape has not been separated at all. After these nitrogen elements are burned, nitrogen oxides (NO, NO2 , N 2 such as O, etc. is seriously polluted; 2) A large amount of organic matter, nitrogen, phosphorus and other elements are effective resources to increase soil fertility. However, when used for fuel incineration, it not only causes pollution but also results in huge waste of resources.

[0005] Therefore, when disposing of and utilizing cow dung, it is necessary to consider both the uses of different components and the possible secondary pollution. Through reasonable technical measures, improving the performance of cow dung components has broad research and application prospects in the preparation of new biomass fuels and the production of highly efficient soil improvement fertilizers. Summary of the Invention

[0006] The object of the present invention is to provide a method for preparing biomass fuel from cow dung and recovering nitrogen and phosphorus.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] The cow dung is conditioned and dehydrated, and a combustible material with a certain calorific value, a combustion aid and a denitration agent are added to the solid-phase fibrous dung obtained by solid-liquid separation. After mixing, it is pressed to obtain biomass fuel; the separated liquid phase is concentrated by coagulation and centrifugation to complete the recovery of nitrogen and phosphorus in the liquid phase.

[0009] The cow dung is repeatedly conditioned and dehydrated until the water content of the solid-phase fibrous dung is lower than 60%; then a combustible material with a certain calorific value, a combustion aid and a denitration agent are sequentially added to the solid-phase fibrous dung. After mixing, it is pressed to obtain biomass fuel.

[0010] The conditioning and dehydration is to mix cow dung and clear water in a mass ratio of 1:3 - 1:5, add sodium persulfate for oxidation, and the added mass ratio of sodium persulfate is 0.3% - 1.0% (that is, sodium persulfate accounts for 0.3% - 1.0% of the total mass of the system). Through one-time extrusion dehydration, the water content of the fibrous solid-phase dung is lower than 70%; then the fibrous solid-phase dung after one-time extrusion dehydration is mixed with clear water again, with a mass ratio of 1:1 - 1:2. After uniform mixing, secondary extrusion dehydration is carried out until the water content of the solid-phase fibrous dung is lower than 60%.

[0011] For the liquid phase separated by the one-time extrusion dehydration, under strong stirring, an appropriate amount of polyferric sulfate is added. After uniform mixing, it is left to stand and precipitate, and then placed in a centrifuge for micro-particle concentration to complete the recovery of nitrogen and phosphorus. The upper clear liquid is reused for reducing the viscosity and conditioning of cow dung.

[0012] The pH adjustment range of the system before each extrusion dehydration is 6.5 - 7; the pressure range during extrusion dehydration is controlled at 0.6 - 0.8 Mpa.

[0013] The reagent used to adjust the pH is dilute sulfuric acid.

[0014] The combustible waste with a certain calorific value is biomass shells, dried coal slime, and dehydrated and dried sludge from domestic sewage treatment plants. The mass ratio of solid-phase fiber feces: biomass shells: dried coal slime: dehydrated and dried sludge is (2 - 7):(1 - 6):1:1.

[0015] Further, the mixture of solid-phase fiber feces: biomass shells: dried coal slime: dehydrated and dried sludge with a mass ratio of (2 - 7):(1 - 6):1:1 is dried, then ground and passed through a 20-mesh sieve. Even further, the mass ratio of solid-phase fiber feces: biomass shells: dried coal slime: dehydrated and dried sludge is 4:4:1:1.

[0016] The biomass shells are peanut shells.

[0017] The combustion aid is one or a mixture of several of urea, iron-manganese sludge, and magnesite waste residue; among them, the added mass ratio of the combustion aid is 1% - 3%.

[0018] The denitration agent is one or a mixture of several of molecular sieve, phosphogypsum, tourmaline waste residue, alkali residue, and waste salt mud; among them, the added mass ratio of the denitration agent is 5% - 8%.

[0019] The concentration after adding polyferric sulfate is 5 - 7 g / L, that is, the concentration of polyferric sulfate in the liquid phase is 5 - 7 g / L.

[0020] Preferably, the solid-phase fiber feces obtained by solid-liquid separation are dried and then added with combustible materials with a certain calorific value, a combustion aid, and a denitration agent. After mixing, they are pressed to form biomass fuel; the drying is to place the solid-phase fiber feces in an electrothermal constant-temperature forced-air drying oven and dry them at 105°C to constant weight to control the influence of the moisture content on the calorific value of the composite fuel. The dried solid-phase fiber feces are further ground and passed through a 20-mesh sieve.

[0021] The advantages of the present invention:

[0022] The main purpose of the present invention is to resourcefully utilize cow dung. The specific technical measures are through multi-stage treatment, thinning and viscosity reduction of the ruminant mucus and saccharides carried in the feces, reducing the binding state of ruminant mucus with fiber and crude protein, and then squeezing and dehydrating through a special device to separate the fiber solid from the fecal liquid. The dehydrated fiber-containing solid phase is further thinned and squeezed for dehydration. Through the second solid-liquid separation, the crude protein ratio in the solid-phase feces is reduced, and the cellulose and lignin-like solid phases are recovered and biomass fuel is prepared. At the same time, NO x emissions are controlled; micro-particle concentration is carried out through coagulation and centrifugation to achieve the concentrated recovery of organic nitrogen and dissolved nitrogen and phosphorus.

[0023] The method for producing biomass fuel with beef cattle manure as the main raw material has simple steps. The key of the invention is to carry out viscosity reduction and conditioning and pressing dehydration in two steps before the fuel is finished, so as to realize the separate recovery of utilizable fibers, nitrogen and phosphorus in cow dung. Then, combustible materials, combustion aids and denitration agents are added to the dehydrated solid-phase fiber manure, so that the prepared fuel has the advantages of high calorific value, easy combustion, and low SO 2 and NO x emission. Description of the Drawings

[0024] Figure 1 It is a combustion experimental device for the environmental protection fuel prepared from the solid-phase fiber extracted from cow dung (the absorption liquid is prepared from sulfanilic acid, N-(1-Naphthyl)ethylenediamine dihydrochloride and glacial acetic acid, and the oxidation liquid is an acidic potassium permanganate solution (ρ = 25 g / L)). Detailed Implementation Modes

[0025] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] The experimental methods, materials and reagents used in the following embodiments are all conventional methods, materials and reagents unless otherwise specified.

[0027] Example 1: Conditioning, viscosity reduction and primary dehydration treatment of cow dung

[0028] The collected cow dung sample is subjected to viscosity reduction and primary extrusion dehydration treatment. First, the rumination mucus and saccharides in the cow dung are diluted to reduce viscosity, and the binding condition of rumination mucus with fibers and crude protein is reduced; specifically:[[]]

[0029] The cow dung and water are fully mixed according to a mass ratio of 1:3, stirred into a viscous mud shape, and 0.5% (calculated based on the total mass of the cow dung mixture) of sodium persulfate (Na 2 S 2 O 8 ) is added and stirred at high speed to disperse evenly, and then 1 mol / L of dilute sulfuric acid (H 2 SO 4 ) is slowly added dropwise to adjust the pH to 6.8.

[0030] Then, through a livestock and poultry manure extrusion dehydrator, primary pressing dehydration is carried out by an extrusion type solid-liquid separation method. At this time, the pressure is controlled at 0.6 Mpa to realize the separation of fiber solid manure and manure liquid, and the obtained solid phase is the fiber-containing solid-phase manure after primary dehydration treatment. The liquid phase obtained after pressing filtration is saved and recycled in the manner of Example 7 to carry out coagulation to recover nitrogen and phosphorus nutrients.

[0031] Determination of the moisture content of fibrous solid feces: An appropriate amount of fibrous solid feces after primary dehydration was dried to a constant weight in an electrothermal constant temperature forced air drying oven at 105 °C, and its moisture content was measured to be 67.8%.

[0032] Example 2: Secondary dehydration treatment of cow dung

[0033] The fibrous solid feces after the above-mentioned primary dehydration treatment were subjected to secondary solid-liquid mixing and secondary extrusion dehydration treatment. Specifically:

[0034] The fibrous solid feces after primary dehydration treatment were mixed with clear water in a mass ratio of 1:2, stirred into a viscous mud, and then 1 mol / L dilute sulfuric acid (H 2 SO 4 ) was slowly added dropwise to adjust the pH to 6.8.

[0035] Then, through a livestock and poultry manure extrusion dehydrator, secondary extrusion dehydration was carried out by an extrusion type solid-liquid separation method. At this time, the pressure was controlled at 0.8 Mpa to achieve the separation of the fibrous solid phase and the manure liquid. The obtained solid phase was the fibrous solid feces after secondary dehydration treatment. The liquid phase obtained after pressure filtration could be used for the solid-liquid blending in Example 1 and replaced clear water.

[0036] Determination of the moisture content of solid fiber feces: An appropriate amount of fibrous solid feces after secondary dehydration was dried to a constant weight in an electrothermal constant temperature forced air drying oven at 105 °C, and its moisture content was measured to be 54.7%.

[0037] Example 3: Preparation of biomass fuel and calorific value comparison

[0038] Using the above-mentioned fibrous solid feces after secondary dehydration and drying (cow dung after secondary dehydration and drying) as the main raw material, the specific drying operation was to place the fibrous solid feces after secondary dehydration in an electrothermal constant temperature forced air drying oven at 105 °C and dry to a constant weight to control the influence of moisture content on the calorific value of the composite fuel; then it was ground and passed through a 20-mesh sieve, and stored in a sealed manner for standby.

[0039] The fibrous solid feces after secondary dehydration and drying were mixed with peanut shells, dried coal slime, and dehydrated and dried sludge in a mass ratio of: (1) 7:1:1:1; (2) 6:2:1:1; (3) 5:3:1:1; (4) 4:4:1:1. Then they were respectively placed in an electrothermal constant temperature forced air drying oven at 105 °C and dried to a constant weight, then ground and passed through a 20-mesh sieve, stored in a sealed manner for standby, and the calorific values of the above materials were measured.

[0040] Weigh 1 g of each sample with different mixing ratios and measure the fuel calorific value in a calorimeter. The atmosphere gas for the experiment was 99.99% oxygen (O 2 ).

[0041] The dehydrated and dried sludge is taken from the sludge after aerobic drying in a domestic sewage treatment plant in Shenyang, the peanut shells are taken from the dried peanut shells in a peanut planting area in Jinzhou City, Liaoning Province, and the dried coal slime raw material comes from a coal washing plant in Liaoning Province. The raw materials used in the experiment are pretreated by drying with the fibrous solid feces.

[0042] The influence of different calorific value waste blending ratios on the calorific value of cow dung biomass fuel is shown in the following table.

[0043] Table 1 Material mixing ratio and calorific value (dry weight)

[0044]

[0045]

[0046] It can be seen that when the blending ratio of cow dung: peanut shells: dried coal slime: dehydrated and dried sludge after secondary dehydration and drying is 4:4:1:1, the calorific value of the prepared fuel is the best, and the calorific value is 3982.9 kcal / kg, which is 1025.6 kcal / kg higher than that of the original cow dung biomass fuel and 223.6 kcal / kg higher than that of the cow dung biomass fuel after secondary dehydration and drying.

[0047] Example 4: Influence of combustion improver on fuel performance

[0048] Add 1%, 2%, and 3% of magnesite waste residue as a combustion improver to the high-calorific value composite fuel prepared in Example 3 (the blending ratio of cow dung: peanut shells: dried coal slime: dehydrated and dried sludge after secondary dehydration and drying is 4:4:1:1) to improve the combustion performance of the composite fuel. After fully mixing evenly, a thermogravimetric analysis experiment is carried out, and at the same time, the material obtained in Example 3 (that is, the high-calorific value composite fuel, the blending ratio of cow dung: peanut shells: dried coal slime: dehydrated and dried sludge after secondary dehydration and drying is 4:4:1:1) is used as a control.

[0049] The combustion performance of the composite biomass fuel is measured by thermogravimetric analysis, and the specific measurement and comparison results are shown in the following table.

[0050] Table 2 Influence of adding combustion improver on the characteristics of the prepared fuel

[0051]

[0052] It can be seen that compared with before the addition of the combustion improver, the addition of the combustion improver effectively improves the combustion performance of the composite fuel, and the fuel performance improvement tends to be flat after the addition amount is 2%. Therefore, the optimal addition amount of the combustion improver is 2%.

[0053] Example 5: Influence of adding denitration agent on the tail gas emission after fuel combustion

[0054] Tourmaline waste residue (calcium carbide slag) and phosphogypsum are selected as denitration agents to achieve the purpose of reducing the emissions of nitrogen oxides (NO X ) during the combustion of composite fuels. The collected tourmaline waste residue and phosphogypsum are placed in an electrothermal constant temperature forced air drying oven and dried at 105 °C until constant weight. Different mass ratios of denitration agents are added to the composite fuel obtained in Example 4, and after mixing with the composite fuel obtained in Example 4, it is reserved for use.

[0055] The tourmaline waste residue is taken from the industrial waste residue generated after calcium carbide is used to produce acetylene gas in a certain acetylene gas factory in Liaoning. The main components are CaO and Ca(OH) 2 , and it contains a small amount of SiO 2 , MgO, etc.; the phosphogypsum is taken from the phosphogypsum waste generated during the production of phosphate fertilizer in a certain phosphate fertilizer factory in Liaoning. The main component is CaSO 4 .

[0056] The emission concentration of nitrogen oxides (NO x ) before and after co-combustion. The combustion experiment is carried out in a tubular furnace, and the experimental device is as Figure 1 shown.

[0057] During the experiment, 1 g of the composite fuel sample is weighed and placed in a porcelain boat, and the porcelain boat is placed in the heating section of the tubular furnace. First, O 2 is introduced, and the flow rate is maintained at 30 mL / min for 30 min to evacuate the residual air in the tubular furnace; then the heating program is set to increase the temperature from room temperature to 800 °C at a heating rate of 40 °C / min -1 . After stabilization, pyrolysis is maintained for 30 min to completely burn out the material, and the flue gas components are measured after being absorbed by the absorption liquid placed in the absorption bottle.

[0058] The determination of the content of nitrogen oxides (NO x ) adopts the N-(1-Naphthyl)ethylenediamine dihydrochloride spectrophotometric method of HJ 479-2009. Nitrogen oxides include NO and NO 2 , etc. During sampling, NO 2 in the gas is first absorbed by the absorption liquid in the first absorption bottle to generate nitrous acid and nitric acid, while low-valent oxides such as NO are not absorbed by the first absorption liquid, but are oxidized to NO 2 by the acidic potassium permanganate solution oxidation tube and then absorbed by the absorption liquid in the second absorption bottle in series, also generating nitrous acid and nitric acid. In each absorption bottle, nitrous acid reacts with sulfanilic acid to form a diazo reaction, and then couples with N-(1-Naphthyl)ethylenediamine dihydrochloride to show a rose color. According to the depth of the color, it is determined by spectrophotometry at a wavelength of 540 nm.

[0059] Table 3 Comparison of nitrogen oxide (NOx) emission concentrations before and after co-combustion

[0060]

[0061] It can be seen that compared with the direct combustion of raw cow dung, the emissions of nitrogen oxides (NO x ) of the cow dung biomass fuel after secondary dehydration and drying are reduced; when the mass ratio of the composite fuel to the tourmaline waste residue is 10:0.5, the emission reduction effect is the best. Compared with the sample of Example 4, the emissions of nitrogen oxides of the fuel after adding the denitration agent are all reduced.

[0062] Example 6: Calorific value determination of biomass fuel

[0063] The biomass fuel obtained after blending with tourmaline waste residue (Treatment 4 in Table 3, selecting the composite fuel sample of Example 5: tourmaline waste residue = 10:0.5) was used to measure the calorific value according to the calorific value method of the fuel in Example 3. The calorific value of the biomass fuel obtained after blending with tourmaline waste residue was measured to be 4286.7 kcal / kg, which was 1329.4 kcal / kg higher than that of the raw cow dung biomass fuel (2957.3 kcal / kg). Obviously, the combustion effect of the biomass fuel prepared according to the present invention is significantly better than that of the general biomass fuel mainly made of cow dung.

[0064] Example 7: Compression molding of biomass fuel

[0065] The prepared biomass fuel raw materials were placed in a tablet press mold (diameter 3 cm, height 2.5 cm), and a compression molding experiment was carried out under the conditions of controlling the pressure at 15 MPa and the pressure holding time at 3 min to prepare biomass fuel blocks.

[0066] Example 8: Flocculation recovery of nitrogen and phosphorus in the liquid phase of cow dung

[0067] The liquid phase after pressure filtration and preservation in Example 1 was treated to recover nitrogen and phosphorus. Specifically:

[0068] After uniformly mixing by high-speed stirring and separating the extruded dehydrated liquid phase, a polymeric ferric sulfide liquid flocculant was added (the addition amounts of the polymeric ferric sulfide liquid in different treatment groups are shown in Table 4), and it was placed on a magnetic stirrer to continue stirring and mixing uniformly. The stirring rate was 180 r / min, and the stirring time was controlled for 30 min. After standing for 2 h, obvious flocculation stratification was observed, and then it was placed in a high-speed centrifuge and centrifuged at a speed of 8000 r / min for 10 min. The supernatant was taken to measure the contents of suspended solids, COD, total nitrogen, and total phosphorus. For the content of suspended solids, 50 mL of the supernatant was taken, filtered through a G3 crucible with a pore size of 20 - 30 μm, and then the intercepted solid matter was dried to a constant weight at a temperature of 105 °C to obtain the content of suspended solids. COD was detected according to the standard "Water Quality - Determination of Chemical Oxygen Demand - Potassium Dichromate Method HJ 828 - 2017". The total nitrogen content was measured using a FOSS Kjeldahl nitrogen analyzer 8400. The total phosphorus content was determined according to "Water Quality - Determination of Total Phosphorus - Ammonium Molybdate Spectrophotometric Method GB / T 11893 - 1989".

[0069] Table 4 Changes in the Contents of Substances in the Liquid Phase of Flocculation Treatment

[0070]

[0071] As can be seen from Table 4, when the concentration of the added polymeric ferric sulfide is 5 g / L, the separation of substances and water in the liquid phase is relatively complete. After flocculation, it was allowed to stand and precipitate, and the supernatant was taken to measure the contents of suspended solids, COD, total nitrogen, and total phosphorus. Compared with the original liquid phase, most of the nitrogen and phosphorus nutrients in the manure liquid were concentrated in the flocs during the flocculation process, which can be used for the preparation of nitrogen and phosphorus fertilizers. The supernatant was then recycled for the viscosity reduction, conditioning, and dehydration treatment of cow dung in Examples 1 and 2, replacing fresh water, for the viscosity reduction and conditioning of cow dung.

[0072] The above describes the present invention and its implementation manners, and it is only the preferred embodiment of the present invention, and is not used to limit the present invention. Generally speaking, if those of ordinary skill in the art are inspired by it and design similar structural manners and embodiments without creative efforts without departing from the purpose of the present invention, they should be included within the protection scope of the present invention.

Claims

1. A method for preparing biomass fuel and recovering nitrogen and phosphorus using cow dung, characterized in that: The cow dung is tempered and dehydrated, and the solid-liquid separation results in the addition of combustible materials with a certain calorific value, combustion aids and denitrification agents to the solid-phase fibrous dung, which is then mixed and pressed to produce biomass fuel. The separated liquid phase is concentrated into microparticles by coagulation and centrifugation to complete the recovery of liquid nitrogen and phosphorus.

2. The method according to claim 1, characterized in that: The cow dung is repeatedly tempered and dehydrated until the water content of the solid fibrous dung is less than 60%; then combustible materials with a certain calorific value, combustion aids and denitrification agents are added to the solid fibrous dung in sequence, and the mixture is pressed to obtain biomass fuel.

3. The method according to claim 1 or 2, characterized in that: The conditioning and dehydration process comprises the following steps: mixing cow dung and clean water in a mass ratio of 1:3-1:5, adding sodium persulfate for oxidation, wherein the mass ratio of the added sodium persulfate is 0.3%-1.0%; performing a first extrusion dehydration process to reduce the moisture content of the fiber solid-phase feces to less than 70%; and then mixing the fiber solid-phase feces after the first extrusion dehydration process with clean water again in a mass ratio of 1:1-1:2, and performing a second extrusion dehydration process after the mixing process to reduce the moisture content of the solid-phase fiber feces to less than 60%.

4. The method according to claim 3, characterized in that: The liquid phase after the first extrusion dehydration separation is added with an appropriate amount of polyferric sulfate under strong stirring, mixed evenly and allowed to settle, and then placed in a centrifuge for micro-particle concentration to complete nitrogen and phosphorus recovery, and the upper clear liquid is reused for viscosity reduction and conditioning of cow dung.

5. The resource recycling method according to claim 3, characterized in that: The pH of the system is adjusted to 6.5-7 before each extrusion dehydration; the pressure during the extrusion dehydration is controlled to be 0.6-0.8Mpa.

6. The method according to claim 1 or 2, characterized in that: The combustible materials with a certain calorific value are biomass shells, dried coal slime and dehydrated dried sludge from a domestic sewage treatment plant, and the mass ratio of solid fiber feces: biomass shells: dried coal slime: dehydrated dried sludge is (2-7): (1-6): 1:

1.

7. The method according to claim 1 or 2, characterized in that: The combustion aid is one or a mixture of urea, iron-manganese sludge, and magnesite waste residue; wherein the added mass ratio of the combustion aid is 1%-3%.

8. The method according to claim 1 or 2, characterized in that: The denitrification agent is one or a mixture of molecular sieve, phosphogypsum, tourmaline waste residue, alkali residue, and waste salt mud; wherein the added mass ratio of the denitrification agent is 5%-8%.

9. The method according to claim 4, characterized in that: The concentration of polyferric sulfate after addition is 5-7 g / L.

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