A wet anaerobic fermentation method for livestock and poultry manure and its application

Abstract

The present invention relates to a wet anaerobic fermentation method for livestock and poultry manure and its application, belonging to the field of fermentation technology. The present invention provides a wet anaerobic fermentation method for livestock and poultry manure. The method effectively shortens the startup period of wet anaerobic fermentation of livestock and poultry manure by first enriching the manure and increasing the processing load and then stably fermenting the manure. The methane content of the produced biogas can reach more than 50% 8 to 9 days in advance, and the gas production can be increased by about 18 to 21%; when the processing load of the manure is increased, the carbon-nitrogen ratio is controlled to 20 to 30:1, and the feed concentration is 3 to 5% (much lower than the conventional feed concentration of 10%), the organic load rate is low, and the material acidification phenomenon is not easy to occur; after the strain is enriched, the method gradually increases the processing load, and continuously monitors various technical indicators during the processing load increase process until it smoothly enters the stable operation stage, reaches the designed output value, and operates more stably.

Description

Technical Field

[0001] The invention relates to a wet anaerobic fermentation method for livestock and poultry manure and application thereof, belonging to the technical field of fermentation. Background Art

[0002] The large amount of nitrogen, phosphorus and organic matter contained in livestock and poultry manure can produce biogas, biogas liquid and biogas residue after being treated with anaerobic fermentation technology in biogas projects. Among them, biogas can be used to produce natural gas and generate electricity, biogas liquid can be used to irrigate farmland, and biogas residue can be used to produce agricultural fertilizers. The overall benefits are very considerable.

[0003] Anaerobic fermentation technologies for biogas projects are categorized into dry and wet processes. Wet processes involve fermenting materials with sewage treatment to a fermentation concentration below 12%. However, existing wet anaerobic fermentation technologies for biogas projects encounter numerous challenges during construction and startup, such as long startup cycles, low gas production, low methane content, and even inability to properly acidify the materials. Therefore, there is an urgent need for wet anaerobic fermentation technologies that offer a short startup cycle, high gas production, high methane content, and resistance to acidification. Summary of the Invention

[0004] To solve the above problems, the present invention provides a wet anaerobic fermentation method for livestock and poultry manure, which comprises the following steps:

[0005] Enrichment of bacterial strains from manure: Fill the fermentation tank with livestock and poultry manure A with a carbon-nitrogen ratio of 20-30:1 and a solid content of 3-5% and then enrich the bacterial strains;

[0006] Increase the manure treatment load: Livestock and poultry manure B with a carbon-nitrogen ratio of 20-30:1 and a solid content of 8-10% is pumped into the fermentation tank to gradually increase the treatment load. During the period of increasing the treatment load, a cycle of 2-4 days is used, and each cycle is fed every day, which is divided into 6-8 cycles in total. In each cycle, the feed amount of livestock and poultry manure B in the fermentation tank is increased by 20-30% to gradually increase the treatment load in the fermentation tank.

[0007] Stable fermentation of manure: continue to pump livestock and poultry manure B with a carbon-nitrogen ratio of 20-30:1 and a solid content of 8-10% into the fermentation tank for continuous and stable fermentation. During the stable fermentation period, collect biogas, biogas liquid and biogas residue from the fermentation tank.

[0008] In one embodiment of the present invention, the pH of the livestock and poultry manure A is 6.8-7.4.

[0009] In one embodiment of the present invention, the livestock and poultry manure A is prepared by adding water to livestock and poultry manure having a carbon-nitrogen ratio of 20 to 30:1 until the solid content is 3 to 5%, thereby obtaining livestock and poultry manure A.

[0010] In one embodiment of the present invention, in the fecal bacteria enrichment step, the enrichment time of the bacteria is 3 to 5 days, and during the enrichment period, the submersible agitator in the tank is turned on, and the mixture is stirred at a speed of 200 to 300 rpm for 5 to 15 minutes every 1 to 2 hours. At the same time, the temperature difference is controlled to not exceed 2°C per day.

[0011] In one embodiment of the present invention, the pH of the livestock and poultry manure B is 6.8-7.4.

[0012] In one embodiment of the present invention, the livestock and poultry manure B is prepared by adding water to livestock and poultry manure having a carbon-nitrogen ratio of 20 to 30:1 until the solid content reaches 8 to 10%, thereby obtaining livestock and poultry manure B.

[0013] In one embodiment of the present invention, in the step of increasing the manure treatment load, during the feeding cycle, the submersible agitator in the tank is turned on each time the feed is fed, and the agitator is stirred at a speed of 400 to 500 rpm for 5 to 15 minutes, and then the agitation is stopped and the feed is stirred at a speed of 10 to 15 minutes. 3 / h discharge pump flow rate to pump out the material in the fermentation tank, and then at 10 ~ 15m 3 / h feed pump flow rate of livestock and poultry manure B is pumped into the fermentation tank. After each feeding, the submersible agitator in the tank is turned on and stirred at a speed of 400-500 rpm for 5-15 minutes every 1-2 hours to increase the processing load.

[0014] In one embodiment of the present invention, during the step of increasing the manure treatment load, the FOS / TAC in the tank needs to be controlled between 0.2 and 0.4 during the period of increasing the treatment load. At the same time, the temperature in the tank needs to be controlled to continue to rise steadily to 36-40°C.

[0015] In one embodiment of the present invention, in the stable fermentation step of manure, the daily feed amount of livestock and poultry manure B during the stable fermentation period accounts for 3-5% of the total volume of the fermentation tank.

[0016] In one embodiment of the present invention, during the stable fermentation step of manure, the material is fed once a day. Each time the material is fed, the submersible agitator in the tank is turned on and stirred at a speed of 400-500 rpm for 5-15 minutes, and then the stirring is stopped and the material is stirred at a speed of 10-15 minutes. 3 / h discharge pump flow rate to pump out the material in the fermentation tank, and then at 10 ~ 15m 3 / h feed pump flow rate pumps livestock and poultry manure B into the fermentation tank, after each feeding,

[0017] Turn on the submersible agitator in the tank and stir at a speed of 400-500 rpm for 5-15 minutes every 1-2 hours to stabilize the fermentation.

[0018] In one embodiment of the present invention, in the stable fermentation step of manure, the FOS / TAC in the tank is controlled between 0.2 and 0.4 during the stable fermentation period. At the same time, the temperature in the tank needs to be controlled to continue to rise steadily to 36-40°C.

[0019] In one embodiment of the present invention, the livestock and poultry manure is composed of one or more of cow manure, chicken manure, pig manure, sheep manure, horse manure or duck manure.

[0020] The present invention also provides the use of the wet anaerobic fermentation method of livestock and poultry manure in the preparation of biogas, biogas liquid and / or biogas residue.

[0021] The technical solution of the present invention has the following advantages:

[0022] The present invention provides a method for wet anaerobic fermentation of livestock and poultry manure. The method effectively shortens the start-up period of wet anaerobic fermentation of livestock and poultry manure by first enriching the manure and increasing the treatment load and then fermenting the manure stably. The methane content of the produced biogas can reach more than 50% 8 to 9 days in advance, and the gas production can be increased by about 18 to 21%. When the method increases the treatment load of the manure, the carbon-nitrogen ratio is controlled to 20 to 30:1, and the feed concentration is 3 to 5% (much lower than the conventional feed concentration of 10%). The organic load rate is low under this carbon-nitrogen ratio range and feed concentration, and the material acidification phenomenon is not easy to occur. In addition, this carbon-nitrogen ratio range is most conducive to Anaerobic fermentation: when the carbon-nitrogen ratio is too high, the biogas fermentation process is difficult to start and the gas production effect is poor. When the carbon-nitrogen ratio is too low, the excess nitrogen will become free ammonia, causing ammonia poisoning, thereby inhibiting gas production. After the strain is enriched, the method gradually increases the processing load, and continuously monitors various technical indicators during the process of increasing the processing load until it smoothly enters the stable operation stage, reaches the designed output value, and operates more stably. The stirring method of the method adopts stirring for 5 to 15 minutes every 1 to 2 hours, wherein, starting stirring before discharging can prevent material accumulation from causing unsmooth discharging, and stirring after feeding can better mix the newly entered material, which is conducive to anaerobic fermentation to produce biogas. DETAILED DESCRIPTION

[0023] The following examples are provided for a better understanding of the present invention and are not intended to limit the best mode of implementation. They do not limit the content and scope of protection of the present invention. Any product identical or similar to the present invention obtained by anyone under the guidance of the present invention or by combining the features of the present invention with other prior arts shall fall within the scope of protection of the present invention.

[0024] If no specific experimental steps or conditions are specified in the following examples, the experiments were carried out according to the conventional experimental steps or conditions described in the literature in the field. If no manufacturer is specified for the reagents or instruments used, they are all commercially available conventional reagents.

[0025] The solid content involved in the following examples was detected using a muffle furnace drying method, the pH value was detected using pH test paper, the gas production and methane content of the fermentation tank were detected using a flow meter and a biogas composition analyzer, and FOS / TAC was detected using a volatile organic acid (FOS) and total inorganic carbon (TAC) fully automatic potentiometric titrator (titration method).

[0026] Example 1: A wet anaerobic fermentation method for livestock and poultry manure

[0027] This embodiment provides a wet anaerobic fermentation method for livestock and poultry manure, comprising the following steps:

[0028] 1. Manure pretreatment

[0029] Cow dung (C / N of 25:1, taken from the Zhuangzhuang Farm in Fengning, Hebei Province) with a solid content of 20% (manure TS=20%) was poured into a regulating tank, and farm flushing sewage was added at a mass ratio of 1.5:8.5 to the cow dung (cow dung: sewage=1.5:8.5), and the solid content of the cow dung was adjusted to 3% (manure TS=3%, pH=7) to obtain pretreated manure A; cow dung (C / N of 25:1) with a solid content of 20% (manure TS=20%) was poured into a regulating tank, and farm flushing sewage of the same mass as the cow dung was added to adjust the solid content of the cow dung to 10% (manure TS=10%, pH=6.8) to obtain pretreated manure B.

[0030] 2. Enrichment of fecal bacteria

[0031] Pour the pre-treated manure A into the feed tank, and then 3 The pretreated manure A is pumped into the fermentation tank at a feed pump flow rate of / h, 60 tons of which are fed every day, and the fermentation tank is filled with feed for a total of 5 days; after the fermentation tank is filled, the bacteria are enriched for 3 days. During the bacteria enrichment period, the submersible agitator in the tank is turned on and stirred at a speed of 200 rpm for 10 minutes every 1 hour. At the same time, the heating system is turned on to increase the temperature of the material, and the daily temperature difference is controlled to be no more than 2°C.

[0032] 3. Increased manure and sewage treatment load

[0033] Pour the pretreated manure B into the feed tank, and then pump it into the fermentation tank to gradually increase the processing load. During the period of increasing the processing load, every 3 days is a feeding cycle, and the feed is fed every day according to the designed concentration, which is divided into 7 feeding cycles. The feed load increase rate of each feeding cycle is 30% of the existing feed load. In the 7 feeding cycles, each time the feeding is started, the submersible agitator in the tank is stirred at a speed of 400rpm for 10min, and then the stirring is stopped and the stirring is continued at 10m 3 / h discharge pump flow rate to pump out the material in the fermentation tank, and then at 10m3 / h of feed pump flow rate to pump pretreated manure B into the fermentation tank, the feed volume and material pumping volume of 7 cycles are 2 tons, 2.6 tons, 3.4 tons, 4.4 tons, 5.8 tons, 7.6 tons and 10 tons respectively (material pumping volume is equal to feed volume). After each feeding, the submersible agitator in the tank is turned on and stirred at a speed of 400 rpm for 10 minutes every 1 hour to make the newly entered material better mixed, which is conducive to anaerobic fermentation to produce biogas. In addition, during the period of increasing the treatment load, the FOS / TAC in the tank needs to be controlled to be less than 0.4 by using dilute hydrochloric acid and quicklime. At the same time, the temperature in the tank needs to be controlled to rise steadily and steadily by starting the boiler until it reaches 38±2℃.

[0034] 4. Stable fermentation of manure

[0035] Continue to pump the pretreated manure B into the fermentation tank for continuous and stable fermentation. During the stable fermentation period, feed once a day. Each time feeding, turn on the submersible agitator in the tank and stir at a speed of 400 rpm for 10 minutes, then stop stirring and stir at 10m 3 / h discharge pump flow rate to pump out the material in the fermentation tank, and then at 10m 3 / h of feed pump flow rate to pump pretreated manure B into the fermentation tank, each feeding material pumping out and pumping in amount is 10 tons, after each feeding, turn on the submersible agitator in the tank, stirring at 400rpm for 10min every hour to make the newly entered material better mixed, which is conducive to anaerobic fermentation to produce biogas. In addition, during the stable fermentation period, dilute hydrochloric acid and quicklime need to be used to control the FOS / TAC in the tank to be less than 0.4. At the same time, the temperature in the tank needs to be started by controlling the boiler to continue to rise steadily until it reaches 38±2℃.

[0036] Table 1 shows the tank parameters during the wet anaerobic fermentation of livestock and poultry manure. As can be seen from Table 1, during the bacterial enrichment phase, agitation and temperature increase were initiated, increasing the activity of the methanogenic bacteria within the tank, leading to a sharp increase in gas production and methane content. During the load increase phase, feed was fed at the designed concentration, with each cycle lasting three days, for a total of seven cycles. Each cycle saw a 30% increase in feed load, steadily increasing the organic loading rate and thus ensuring the activity of the methanogens. By the 12th day (i.e., the fourth day of stable fermentation), the methane content of the gas produced within the tank exceeded 50%, approximately eight days earlier than with conventional operation. This was due to the rapid filling of the fermenter with low-concentration material during the bacterial enrichment phase, which rapidly cultivated methanogens and expelled air from the tank, rapidly increasing methane content. During the stable fermentation phase, operation began at the designed feed rate and concentration, with daily monitoring of various technical indicators to ensure they remained within reasonable ranges.

[0037] Table 1 Tank parameters during wet anaerobic fermentation of livestock and poultry manure

[0038]

[0039]

[0040] Example 2: A wet anaerobic fermentation method for livestock and poultry manure

[0041] This embodiment provides a wet anaerobic fermentation method for livestock and poultry manure, comprising the following steps:

[0042] 1. Manure pretreatment

[0043] Cow dung with a solid content of 20% (TS of feces = 20%) (C / N of 25:1, taken from the Zhuangzhuang Farm in Fengning, Hebei) and chicken dung with a solid content of 30% (TS of feces = 30%) (C / N of 10:1, taken from the Fengshan Chicken Farm in Fengning, Hebei) were poured into the regulating tank at a mass ratio of 9:4.5, and the farm flushing sewage was added at a mass ratio of 1.35:9.15 (mixed feces: sewage = 1.35:9.15) to the mixed feces to adjust the solid content of the mixed feces to 3% (TS of feces = 30%). The method comprises the following steps: adding cow dung (C / N of 25:1) with a solid content of 20% (manure TS=20%) and chicken dung (C / N of 10:1) with a solid content of 30% (manure TS=30%) into a regulating tank in a mass ratio of 2:1, adding farm flushing wastewater of the same mass as the mixed manure, adjusting the solid content of the mixed manure to 10% (manure TS=10%, pH=7.2), and obtaining pretreated manure B.

[0044] 2. Enrichment of fecal bacteria

[0045] Pour the pre-treated manure A into the feed tank, and then 3 The pretreated manure A is pumped into the fermentation tank at a feed pump flow rate of / h, 60 tons of which are fed every day, and the fermentation tank is filled with feed for a total of 5 days; after the fermentation tank is filled, the bacteria are enriched for 3 days. During the bacteria enrichment period, the submersible agitator in the tank is turned on and stirred at a speed of 200 rpm for 10 minutes every 1 hour. At the same time, the heating system is turned on to increase the temperature of the material, and the daily temperature difference is controlled to be no more than 2°C.

[0046] 3. Increased manure and sewage treatment load

[0047] Pour the pretreated manure B into the feeding pool, and then pump it into the fermentation tank to gradually increase the processing load. During the period of increasing the processing load, every 3 days is a feeding cycle, and the feed is fed every day according to the designed concentration, which is divided into 7 feeding cycles. The feed load increase rate of each feeding cycle is 30% of the existing feed load. In the 7 feeding cycles, each time the feeding is started, the submersible agitator in the tank is stirred at a speed of 400rpm for 10min, and then the stirring is stopped and the stirring is continued at 10m 3 / h discharge pump flow rate to pump out the material in the fermentation tank, and then at 10m 3 / h of feed pump flow rate to pump pretreated manure B into the fermentation tank. The feed volume and material pumping volume of 7 cycles are 2.1 tons, 2.8 tons, 3.5 tons, 4.6 tons, 6 tons, 7.8 tons and 10.5 tons respectively (the material pumping volume is equal to the feed volume). After each feeding, the submersible agitator in the tank is turned on and stirred at a speed of 400 rpm for 10 minutes every 1 hour to better mix the newly entered material, which is conducive to anaerobic fermentation to produce biogas. In addition, during the period of increasing the treatment load, the FOS / TAC in the tank needs to be controlled to be less than 0.4 by using dilute hydrochloric acid and quicklime. At the same time, the temperature in the tank needs to be controlled to rise steadily and steadily by starting the boiler until it reaches 38±2℃.

[0048] 4. Stable fermentation of manure

[0049] Continue to pump the pretreated manure B into the fermentation tank for continuous and stable fermentation. During the stable fermentation period, feed once a day. Each time feeding, turn on the submersible agitator in the tank and stir at a speed of 400 rpm for 10 minutes, then stop stirring and stir at 10m 3 / h discharge pump flow rate to pump out the material in the fermentation tank, and then at 10m 3 / h of feed pump flow rate to pump pretreated manure B into the fermentation tank. The material pumping out and pumping in volume of each feed are both 10.5 tons. After each feeding, the submersible agitator in the tank is turned on and stirred at a speed of 400 rpm for 10 minutes every hour to allow the newly entered material to be better mixed, which is conducive to anaerobic fermentation to produce biogas. In addition, during the stable fermentation period, the FOS / TAC in the tank needs to be controlled to be less than 0.4 by using dilute hydrochloric acid and quicklime. At the same time, the temperature in the tank needs to be controlled to rise steadily by starting the boiler until it reaches 38±2°C.

[0050] Table 2 shows the tank parameters during the wet anaerobic fermentation of livestock and poultry manure. As can be seen from Table 2, during the strain enrichment phase, agitation and temperature increase were initiated, increasing the activity of the methanogenic bacteria within the tank, leading to a sharp increase in gas production and methane content. During the process load increase phase, feed was fed at the designed concentration, with each cycle lasting three days, for a total of seven cycles. Each cycle saw a feed load increase of 30% of the existing feed load, steadily increasing the organic loading rate and thus ensuring the activity of the methanogens. By the 12th day (i.e., the fourth day of stable fermentation) from the first day of feed, the methane content of the gas produced within the tank exceeded 50%, approximately eight days earlier than with conventional operation. This was due to the rapid filling of the fermenter with low-concentration material during the strain enrichment phase, which, firstly, facilitated the rapid cultivation of methanogens and, secondly, allowed the removal of air from the tank, rapidly increasing the methane content. During the stable fermentation phase, operation began at the designed feed rate and concentration, with daily monitoring of various technical indicators to ensure that each remained within a reasonable range.

[0051] Table 2 Tank parameters during wet anaerobic fermentation of livestock and poultry manure

[0052]

[0053] Example 3: A wet anaerobic fermentation method for livestock and poultry manure

[0054] This embodiment provides a wet anaerobic fermentation method for livestock and poultry manure, comprising the following steps:

[0055] 1. Manure pretreatment

[0056] Cow dung with a solid content of 20% (TS of manure = 20%) (C / N of 25:1, taken from the Zhuangzhuang Farm in Fengning, Hebei) and pig dung with a solid content of 10% (TS of manure = 10%) (C / N of 13:1, taken from the Yinhe Pig Farm in Fengning, Hebei) were poured into the regulating tank at a mass ratio of 1:2, and the farm flushing sewage was added at a mass ratio of 9:31 (mixed manure: sewage = 9:31) to the mixed manure to adjust the solid content of the mixed manure to 3% (TS of manure = 3%, pH = 7.1). , obtaining pretreated manure A; pouring cow dung (C / N of 25:1) with a solid content of 20% (manure TS = 20%) and pig manure (C / N of 13:1) with a solid content of 10% (manure TS = 10%) into a regulating tank in a mass ratio of 2:1, adding farm flushing sewage with a mass ratio of 3:1 to the mixed manure (mixed manure: sewage = 3:1), adjusting the solid content of the mixed manure to 10% (manure TS = 10%, pH = 7.0), and obtaining pretreated manure B.

[0057] 2. Enrichment of fecal bacteria

[0058] Pour the pre-treated manure A into the feed tank, and then3 The pretreated manure A is pumped into the fermentation tank at a feed pump flow rate of / h, 60 tons of which are fed every day, and the fermentation tank is filled with feed for a total of 5 days; after the fermentation tank is filled, the bacteria are enriched for 3 days. During the bacteria enrichment period, the submersible agitator in the tank is turned on and stirred at a speed of 200 rpm for 10 minutes every 1 hour. At the same time, the heating system is turned on to increase the temperature of the material, and the daily temperature difference is controlled to be no more than 2°C.

[0059] 3. Increased manure and sewage treatment load

[0060] Pour the pretreated manure B into the feeding pool, and then pump it into the fermentation tank to gradually increase the processing load. During the period of increasing the processing load, every 3 days is a feeding cycle, and the feed is fed every day according to the designed concentration, which is divided into 7 feeding cycles. The feed load increase rate of each feeding cycle is 30% of the existing feed load. In the 7 feeding cycles, each time the feeding is started, the submersible agitator in the tank is stirred at a speed of 400rpm for 10min, and then the stirring is stopped and the stirring is continued at 10m 3 / h discharge pump flow rate to pump out the material in the fermentation tank, and then at 10m 3 / h of feed pump flow rate to pump pretreated manure B into the fermentation tank. The feed volume and material pumping volume of 7 cycles are 2.1 tons, 2.7 tons, 3.5 tons, 4.6 tons, 6 tons, 7.6 tons and 10 tons respectively (the material pumping volume is equal to the feed volume). After each feeding, the submersible agitator in the tank is turned on and stirred at a speed of 400 rpm for 10 minutes every 1 hour to better mix the newly entered material, which is conducive to anaerobic fermentation to produce biogas. In addition, during the period of increasing the treatment load, the FOS / TAC in the tank needs to be controlled to be less than 0.4 by using dilute hydrochloric acid and quicklime. At the same time, the temperature in the tank needs to be controlled to rise steadily and steadily by starting the boiler until it reaches 38±2℃.

[0061] 4. Stable fermentation of manure

[0062] Continue to pump the pretreated manure B into the fermentation tank for continuous and stable fermentation. During the stable fermentation period, feed once a day. Each time feeding, turn on the submersible agitator in the tank and stir at a speed of 400 rpm for 10 minutes, then stop stirring and stir at 10m 3 / h discharge pump flow rate to pump out the material in the fermentation tank, and then at 10m 3 / h of feed pump flow rate to pump pretreated manure B into the fermentation tank, each feeding material pumping out and pumping in amount is 10 tons, after each feeding, turn on the submersible agitator in the tank, stirring at 400rpm for 10min every hour to make the newly entered material better mixed, which is conducive to anaerobic fermentation to produce biogas. In addition, during the stable fermentation period, dilute hydrochloric acid and quicklime need to be used to control the FOS / TAC in the tank to be less than 0.4. At the same time, the temperature in the tank needs to be started by controlling the boiler to continue to rise steadily until it reaches 38±2℃.

[0063] Table 3 shows the tank parameters during the wet anaerobic fermentation of livestock and poultry manure. As can be seen from Table 3, during the bacterial enrichment phase, agitation and temperature increase were initiated, increasing the activity of the methanogenic bacteria within the tank, leading to a sharp increase in gas production and methane content. During the load increase phase, feed was fed at the designed concentration. Each cycle consisted of seven cycles, each lasting three days. The feed load was increased by 30% of the existing feed load in each cycle, steadily increasing the organic loading rate and thus ensuring the activity of the methanogens. By the 12th day (i.e., the fourth day of stable fermentation) from the first day of feed, the methane content of the gas produced within the tank exceeded 50%, approximately eight days earlier than with conventional operation. This was due to the rapid filling of the fermenter with low-concentration material during the bacterial enrichment phase, which, firstly, facilitated the rapid cultivation of methanogens and, secondly, allowed the removal of air from the tank, leading to a rapid increase in methane content. During the stable fermentation phase, operation began at the designed feed rate and concentration, with daily monitoring of various technical indicators to ensure that each remained within a reasonable range.

[0064] Table 3 Tank parameters during wet anaerobic fermentation of livestock and poultry manure

[0065]

[0066]

[0067] Example 4: A wet anaerobic fermentation method for livestock and poultry manure

[0068] This embodiment provides a wet anaerobic fermentation method for livestock and poultry manure, comprising the following steps:

[0069] 1. Manure pretreatment

[0070] Cow dung (C / N of 25:1, taken from the Zhuangzhuang Farm in Fengning, Hebei Province) with a solid content of 20% (manure TS=20%) was poured into a regulating tank, and farm flushing sewage was added at a mass ratio of 1.5:8.5 to the cow dung (cow dung: sewage=1.5:8.5), and the solid content of the cow dung was adjusted to 3% (manure TS=3%, pH=7) to obtain pretreated manure A; cow dung (C / N of 25:1) with a solid content of 20% (manure TS=20%) was poured into a regulating tank, and farm flushing sewage of the same mass as the cow dung was added to adjust the solid content of the cow dung to 10% (manure TS=10%, pH=6.8) to obtain pretreated manure B.

[0071] 2. Enrichment of fecal bacteria

[0072] Pour the pre-treated manure A into the feed tank, and then 3The pretreated manure A is pumped into the fermentation tank at a feed pump flow rate of / h, 60 tons of which are fed every day, and the fermentation tank is filled with feed for a total of 5 days; after the fermentation tank is filled, the bacteria are enriched for 3 days. During the bacteria enrichment period, the submersible agitator in the tank is turned on and stirred at a speed of 200 rpm for 10 minutes every 2 hours. At the same time, the heating system is turned on to increase the temperature of the material, and the daily temperature difference is controlled to be no more than 2°C.

[0073] 3. Increased manure and sewage treatment load

[0074] Pour the pretreated manure B into the feeding pool, and then pump it into the fermentation tank to gradually increase the processing load. During the period of increasing the processing load, every 3 days is a feeding cycle, and the feed is fed every day according to the designed concentration, which is divided into 7 feeding cycles. The feed load increase rate of each feeding cycle is 30% of the existing feed load. In the 7 feeding cycles, each time the feeding is started, the submersible agitator in the tank is stirred at a speed of 400rpm for 10min, and then the stirring is stopped and the stirring is continued at 10m 3 / h discharge pump flow rate to pump out the material in the fermentation tank, and then at 10m 3 / h of feed pump flow rate to pump pretreated manure B into the fermentation tank, the feed volume and material pumping volume of 7 cycles are 2 tons, 2.6 tons, 3.4 tons, 4.4 tons, 5.8 tons, 7.6 tons and 10 tons respectively (material pumping volume is equal to feed volume). After each feeding, the submersible agitator in the tank is turned on and stirred at a speed of 400 rpm for 10 minutes every 1 hour to make the newly entered material better mixed, which is conducive to anaerobic fermentation to produce biogas. In addition, during the period of increasing the treatment load, the FOS / TAC in the tank needs to be controlled to be less than 0.4 by using dilute hydrochloric acid and quicklime. At the same time, the temperature in the tank needs to be controlled to rise steadily and steadily by starting the boiler until it reaches 38±2℃.

[0075] 4. Stable fermentation of manure

[0076] Continue to pump the pretreated manure B into the fermentation tank for continuous and stable fermentation. During the stable fermentation period, feed once a day. Each time feeding, turn on the submersible agitator in the tank and stir at a speed of 400 rpm for 10 minutes, then stop stirring and stir at 10m 3 / h discharge pump flow rate to pump out the material in the fermentation tank, and then at 10m 3 / h of feed pump flow rate to pump pretreated manure B into the fermentation tank, each feeding material pumping out and pumping in amount is 10 tons, after each feeding, turn on the submersible agitator in the tank, stir at 400rpm for 10min every 2h to make the newly entered material better mixed, which is conducive to anaerobic fermentation to produce biogas, and during the stable fermentation period, dilute hydrochloric acid and quicklime need to be used to control the FOS / TAC in the tank to be less than 0.4, at the same time, the boiler needs to be started to control the temperature in the tank to continue to rise steadily until 38±2℃.

[0077] The parameters in the tank during the wet anaerobic fermentation of livestock and poultry manure are shown in Table 4. As can be seen from Table 4, the feeding method is the same as that in Example 1, that is, the low-concentration material first quickly fills the fermentation tank and enters the strain enrichment stage, and then gradually increases the processing load. Every 3 days is a cycle, and the material is fed every day according to the designed concentration. It is divided into 7 cycles in total, and the feed load increase rate in each cycle is 30% of the existing feed load, and finally enters the stable fermentation stage; the difference from Example 1 is that the stirring method is changed, from stirring for 10 minutes at a speed of 200 or 400 rpm every 1 hour to stirring once every 2 hours. Biogas can also be produced and the methane content can reach 60%. Compared with Example 1, the gas production is reduced by 12%, and it takes 14 days (calculated from the first day of feeding) for the methane content to reach more than 50%. Compared with Example 1, it is delayed by 2 days, but it is still much better than Comparative Examples 1 to 2.

[0078] Table 4 Tank parameters during wet anaerobic fermentation of livestock and poultry manure

[0079]

[0080]

[0081] Example 5: A wet anaerobic fermentation method for livestock and poultry manure

[0082] This embodiment provides a wet anaerobic fermentation method for livestock and poultry manure, comprising the following steps:

[0083] 1. Manure pretreatment

[0084] Cow dung with a solid content of 20% (TS of manure = 20%) (C / N of 25:1, taken from the Zhuangzhuang Farm in Fengning, Hebei) and pig dung with a solid content of 10% (TS of manure = 10%) (C / N of 13:1, taken from the Yinhe Pig Farm in Fengning, Hebei) were poured into the regulating tank at a mass ratio of 1:2, and the farm flushing sewage was added at a mass ratio of 9:31 (mixed manure: sewage = 9:31) to the mixed manure to adjust the solid content of the mixed manure to 3% (TS of manure = 3%, pH = 6.9). , obtaining pretreated manure A; pouring cow dung (C / N of 25:1) with a solid content of 20% (manure TS = 20%) and pig manure (C / N of 13:1) with a solid content of 10% (manure TS = 10%) into a regulating tank in a mass ratio of 2:1, adding farm flushing sewage with a mass ratio of 3:1 to the mixed manure (mixed manure: sewage = 3:1), adjusting the solid content of the mixed manure to 10% (manure TS = 10%, pH = 7.0), and obtaining pretreated manure B.

[0085] 2. Enrichment of fecal bacteria

[0086] Pour the pre-treated manure A into the feed tank, and then 3The pretreated manure A is pumped into the fermentation tank at a feed pump flow rate of / h, 60 tons of which are fed every day, and the fermentation tank is filled with feed for a total of 5 days; after the fermentation tank is filled, the bacteria are enriched for 3 days. During the bacteria enrichment period, the submersible agitator in the tank is turned on and stirred at a speed of 200 rpm for 10 minutes every 2 hours. At the same time, the heating system is turned on to increase the temperature of the material, and the daily temperature difference is controlled to be no more than 2°C.

[0087] 3. Increased manure and sewage treatment load

[0088] Pour the pretreated manure B into the feed tank, and then pump it into the fermentation tank to gradually increase the processing load. During the period of increasing the processing load, every 3 days is a feeding cycle, and the feed is fed every day according to the designed concentration, which is divided into 7 feeding cycles. The feed load increase rate of each feeding cycle is 30% of the existing feed load. In the 7 feeding cycles, each time the feeding is started, the submersible agitator in the tank is stirred at a speed of 400rpm for 10min, and then the stirring is stopped and the stirring is continued at 10m 3 / h discharge pump flow rate to pump out the material in the fermentation tank, and then at 10m 3 / h of feed pump flow rate to pump pretreated manure B into the fermentation tank, the feed volume and material pumping volume of 7 cycles are 2.1 tons, 2.7 tons, 3.5 tons, 4.6 tons, 6 tons, 7.6 tons and 10 tons respectively (material pumping volume is equal to feed volume). After each feeding, the submersible agitator in the tank is turned on and stirred at a speed of 400 rpm for 10 minutes every 2 hours to make the newly entered material better mixed, which is conducive to anaerobic fermentation to produce biogas. In addition, during the period of increasing the treatment load, the FOS / TAC in the tank needs to be controlled to be less than 0.4 by using dilute hydrochloric acid and quicklime. At the same time, the temperature in the tank needs to be controlled to rise steadily and steadily by starting the boiler to 38±2℃.

[0089] 4. Stable fermentation of manure

[0090] Continue to pump the pretreated manure B into the fermentation tank for continuous and stable fermentation. During the stable fermentation period, feed once a day. Each time feeding, turn on the submersible agitator in the tank and stir at a speed of 400 rpm for 10 minutes, then stop stirring and stir at 10m 3 / h discharge pump flow rate to pump out the material in the fermentation tank, and then at 10m 3 / h of feed pump flow rate to pump pretreated manure B into the fermentation tank, each feeding material pumping out and pumping in amount is 10 tons, after each feeding, turn on the submersible agitator in the tank, stirring at 400rpm for 10min every hour to make the newly entered material better mixed, which is conducive to anaerobic fermentation to produce biogas. In addition, during the stable fermentation period, dilute hydrochloric acid and quicklime need to be used to control the FOS / TAC in the tank to be less than 0.4. At the same time, the temperature in the tank needs to be started by controlling the boiler to continue to rise steadily until it reaches 38±2℃.

[0091] The parameters in the tank during the wet anaerobic fermentation of livestock and poultry manure are shown in Table 5. As can be seen from Table 5, the feeding method is the same as that in Example 3, that is, the low-concentration material first quickly fills the fermentation tank and enters the bacterial enrichment stage, and then gradually increases the processing load. Every 3 days is a cycle, and the feed is fed every day according to the designed concentration. It is divided into 7 cycles in total, and the feed load increase rate in each cycle is 30% of the existing feed load, and finally enters the stable fermentation stage. The difference from Example 1 is that the stirring method is changed. The stirring is changed from stirring for 10 minutes at a speed of 200 or 400 rpm every 1 hour to stirring once every 2 hours. Biogas can also be produced and the methane content can reach 60%. Compared with Example 3, the gas production is reduced by 10%, and it takes 15 days (calculated from the first day of feeding) for the methane content to reach more than 50%. Compared with Example 3, it is delayed by 3 days, but it is still much better than Comparative Examples 1 to 2.

[0092] Table 5 Tank parameters during wet anaerobic fermentation of livestock and poultry manure

[0093]

[0094]

[0095] Comparative Example 1: A wet anaerobic fermentation method for livestock and poultry manure

[0096] This comparative example provides a wet anaerobic fermentation method for livestock and poultry manure, comprising the following steps:

[0097] 1. Manure pretreatment

[0098] Cow dung (C / N of 25:1) with a solid content of 20% (manure TS = 20%) is poured into a regulating tank, and farm flushing wastewater of the same mass as the cow dung is added to adjust the solid content of the cow dung to 10% (manure TS = 10%, pH value = 7.1) to obtain pretreated manure.

[0099] 2. Start feeding

[0100] Pour the pre-treated manure into the feed tank and then 3 / h feed pump flow rate pump pretreated manure A into the fermentation tank, feed 10 tons per day, a total of 30 days to fill the fermentation tank; after the material in the fermentation tank is submerged in the submersible agitator, turn on the submersible agitator in the tank, stir at a speed of 200 rpm for 10 minutes every hour, at the same time, turn on the heating system to increase the temperature of the material, and control the daily temperature difference to not more than 2 ° C.

[0101] 3. Stable fermentation of manure

[0102] Continue to pump the pretreated manure into the fermentation tank for continuous and stable fermentation. During the stable fermentation period, feed once a day. Each time feeding, turn on the submersible agitator in the tank and stir at a speed of 400 rpm for 10 minutes, then stop stirring and stir at 10m 3 / h discharge pump flow rate to pump out the material in the fermentation tank, and then at 10m 3 / h feed pump flow rate is used to pump pretreated manure into the fermentation tank. The material pumping out and pumping in volume of each feed are both 10 tons. After each feeding, the submersible agitator in the tank is turned on and stirred at a speed of 400rpm for 10 minutes every hour to allow the newly entered material to be better mixed, which is conducive to anaerobic fermentation to produce biogas. In addition, during the stable fermentation period, the FOS / TAC in the tank needs to be controlled to be less than 0.4 by using dilute hydrochloric acid and quicklime. At the same time, the temperature in the tank needs to be started by controlling the continuous and stable rise to 38±2℃.

[0103] The tank parameters during the wet anaerobic fermentation of livestock and poultry manure are shown in Table 6. As can be seen from Table 6, this feeding method starts with the designed feed amount and designed concentration, and the same daily feed amount can also produce biogas with a methane content of 60%. However, compared with Example 1, the gas production is reduced by 18%, and it takes 21 days (calculated from the first day of feeding) for the methane content to reach above 50%, which is a delay of 9 days compared with Example 1.

[0104] Table 6 Tank parameters during wet anaerobic fermentation of livestock and poultry manure

[0105]

[0106] Comparative Example 2: A wet anaerobic fermentation method for livestock and poultry manure This comparative example provides a wet anaerobic fermentation method for livestock and poultry manure, comprising the following steps: 1. Manure pretreatment

[0107] Cow dung (C / N of 25:1) with a solid content of 20% (manure TS=20%) and chicken dung (C / N of 10:1) with a solid content of 30% (manure TS=30%) are poured into a regulating tank at a mass ratio of 2:1, and farm flushing sewage is added at a mass ratio of 6:5.5 to the mixed manure (mixed manure: sewage=6:5.5), and the solid content of the mixed manure is adjusted to 10% (manure TS=10%, pH value=6.7) to obtain pretreated manure.

[0108] 2. Start feeding

[0109] Pour the pre-treated manure into the feed tank and then 3 / h of feed pump flow rate to pump pretreated manure into the fermentation tank, feed 10 tons per day, and feed for 30 days to fill the fermentation tank; after the material in the fermentation tank is submerged in the submersible agitator, turn on the submersible agitator in the tank and stir at a speed of 200rpm for 10 minutes every hour. At the same time, turn on the heating system to increase the temperature of the material, and control the daily temperature difference to not more than 2°C.

[0110] 3. Stable fermentation of manure

[0111] Continue to pump the pretreated manure into the fermentation tank for continuous and stable fermentation. During the stable fermentation period, feed once a day. Each time feeding, turn on the submersible agitator in the tank and stir at a speed of 400 rpm for 10 minutes, then stop stirring and stir at 10m 3 / h discharge pump flow rate to pump out the material in the fermentation tank, and then at 10m 3 / h feed pump flow rate is used to pump pretreated manure into the fermentation tank. The material pumping out and pumping in volume of each feed are both 10 tons. After each feeding, the submersible agitator in the tank is turned on and stirred at a speed of 400rpm for 10 minutes every hour to allow the newly entered material to be better mixed, which is conducive to anaerobic fermentation to produce biogas. In addition, during the stable fermentation period, the FOS / TAC in the tank needs to be controlled to be less than 0.4 by using dilute hydrochloric acid and quicklime. At the same time, the temperature in the tank needs to be started by controlling the continuous and stable rise to 38±2℃.

[0112] The tank parameters during the wet anaerobic fermentation of livestock and poultry manure are shown in Table 7. As can be seen from Table 7, this feeding method starts with the designed feed amount and designed concentration, and the same daily feed amount can also produce biogas with a methane content of 60%. However, compared with Example 2, the gas production is reduced by 21%, and it takes 20 days (calculated from the first day of feeding) for the methane content to reach above 50%, which is an 8-day delay compared with Example 2.

[0113] Table 7 Tank parameters during wet anaerobic fermentation of livestock and poultry manure

[0114]

[0115]

[0116] Experimental Example 1:

[0117] Table 8 shows the statistical results of the average gas production, fermentation time, time when the methane content of the gas produced in the tank reaches 50%, pH and fermentation temperature of Examples 1 to 5 and Comparative Examples 1 to 2.

[0118] As can be seen from Table 8, the gas production of mixed manure fermentation of cow dung and chicken dung is about 10% higher than that of single manure fermentation of cow dung; the gas production of the method of quickly filling the fermentation tank with low-concentration materials and then gradually increasing the load is 18-21% higher than that of the method of steadily feeding the material according to the design concentration and the design feed amount; the methane content reaches 50% 8-9 days earlier when the fermentation tank is quickly filled with low-concentration materials and then gradually increasing the load is 8-9 days earlier when the methane content reaches 50% compared with the method of steadily feeding the material according to the design concentration and the design feed amount; the gas production is 10-12% higher when the stirring method is 10 minutes every 1 hour compared with the stirring method of 10 minutes every 2 hours, and the methane content reaches 50% 2-3 days earlier.

[0119] Table 8 Comparison of tank parameters during wet anaerobic fermentation of livestock and poultry manure

[0120]

[0121]

[0122] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A wet anaerobic fermentation method for livestock and poultry manure, characterized in that: The method comprises the following steps: Enrichment of manure bacteria: A fermentation tank is filled with livestock and poultry manure A having a carbon-nitrogen ratio of 20 to 30:1 and a solid content of 3 to 5%, and then the bacteria are enriched. In the manure bacteria enrichment step, the bacteria enrichment time is 3 to 5 days. During the bacteria enrichment period, a submersible agitator in the tank is turned on and stirred at a speed of 200 to 300 rpm for 5 to 15 minutes every 1 to 2 hours. At the same time, the temperature difference is controlled to not exceed 2°C per day. Increase the manure treatment load: pump livestock and poultry manure B with a carbon-nitrogen ratio of 20-30:1 and a solid content of 8-10% into the fermentation tank to gradually increase the treatment load. During the period of increasing the treatment load, a cycle of 2-4 days is used, and each cycle is fed every day, which is divided into 6-8 cycles. In each cycle, the feed amount of livestock and poultry manure B in the fermentation tank is increased by 20-30% to gradually increase the treatment load in the fermentation tank. In the step of increasing the manure treatment load, the FOS / TAC in the tank needs to be controlled between 0.2 and 0.4 during the period of increasing the treatment load. At the same time, the temperature in the tank needs to be controlled to rise steadily and continuously until it reaches 36-40°C. In the feeding cycle, the submersible agitator in the tank is turned on for each feeding, and stirred at a speed of 400-500rpm for 5-15min, then the stirring is stopped and the temperature is kept at 10-15m 3 / h discharge pump flow rate to pump out the material in the fermentation tank, and then at 10 ~ 15m 3 / h feed pump flow rate pump livestock and poultry manure B into the fermentation tank, each feeding is completed, the tank submersible agitator is turned on, every 1 to 2 hours at a speed of 400 to 500 rpm stirring for 5 to 15 minutes to increase the processing load; Stable fermentation of manure: continue to pump livestock and poultry manure B with a carbon-nitrogen ratio of 20-30:1 and a solid content of 8-10% into the fermentation tank for continuous and stable fermentation. During the stable fermentation period, collect biogas, biogas liquid and biogas residue from the fermentation tank; in the stable fermentation step of manure, control the FOS / TAC in the tank between 0.2 and 0.4 during the stable fermentation period, and at the same time, control the temperature in the tank to continue to rise steadily to 36-40°C; during the stable fermentation period, feed once a day, and each time feed, first turn on the submersible agitator in the tank, stir at a speed of 400-500rpm for 5-15min, then stop stirring, and stir at 10-15m 3 / h discharge pump flow rate to pump out the material in the fermentation tank, and then at 10 ~ 15m 3 / h feed pump flow rate pump livestock and poultry manure B into the fermentation tank, each feeding is completed, the tank submersible agitator is turned on, every 1 to 2 hours at a speed of 400 to 500 rpm for 5 to 15 minutes to stabilize the fermentation; The manure A and manure B are both mixed manure of cow dung and chicken dung.

2. The wet anaerobic fermentation method for livestock and poultry manure according to claim 1, characterized in that: The pH of the livestock and poultry manure A is 6.8-7.4; the preparation method of the livestock and poultry manure A is: adding water to livestock and poultry manure with a carbon-nitrogen ratio of 20-30:1 until the solid content is 3-5%, thereby obtaining the livestock and poultry manure A.

3. The wet anaerobic fermentation method for livestock and poultry manure according to any one of claims 1 to 2, characterized in that: The pH of the livestock and poultry manure B is 6.8-7.4; the preparation method of the livestock and poultry manure B is: adding water to livestock and poultry manure with a carbon-nitrogen ratio of 20-30:1 until the solid content is 8-10%, thereby obtaining the livestock and poultry manure B.

4. The wet anaerobic fermentation method for livestock and poultry manure according to any one of claims 1 to 2, characterized in that: In the step of stable fermentation of manure, the daily feed amount of livestock and poultry manure B during the stable fermentation period accounts for 3-5% of the total volume of the fermentation tank.

5. Use of the wet anaerobic fermentation method of livestock and poultry manure according to any one of claims 1 to 4 in the preparation of biogas, biogas liquid and / or biogas residue.

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