阅读说明：本技术 一种鸡粪与玉米秸秆干发酵快速启动工艺及稳定运行方法 (Chicken manure and corn straw dry fermentation rapid start process and stable operation method ) 是由 王立闯 丁岳峰 高有清 张晓光 于 2020-06-15 设计创作，主要内容包括：本发明涉及一种鸡粪与玉米秸秆干发酵快速启动工艺及稳定运行方法。本发明专利采用鸡粪与玉米秸秆进行干式厌氧发酵,对干玉米秸秆采用“机械粉碎+微生物腐化”的预处理工序后与鸡粪配比混合进行干式厌氧发酵。快速启动工艺采用干法启动,利用特殊培养和驯化污泥进行接种,同时调节反应器初期pH稳定性,提高产甲烷菌活性并有助于甲烷菌的快速繁殖增量,减少调试启动期的碱液添加。本方法实现了干式厌氧发酵系统的快速、稳定启动和后期的稳定运行。(The invention relates to a quick starting process and a stable operation method for dry fermentation of chicken manure and corn straw. The invention discloses a method for preparing corn stalk dry anaerobic fermentation, which comprises the steps of performing dry anaerobic fermentation on chicken manure and corn stalks, and performing dry anaerobic fermentation on the dry corn stalks after a pretreatment process of mechanical crushing and microbial decay. The quick starting process adopts dry starting, utilizes special culture and domesticated sludge for inoculation, simultaneously adjusts the initial pH stability of the reactor, improves the activity of methanogens, is beneficial to quick propagation increment of methanogens, and reduces alkali liquor addition in a debugging starting period. The method realizes the rapid and stable start and the later stable operation of the dry anaerobic fermentation system.)

1. A quick starting process and a stable operation method for dry fermentation of chicken manure and corn straw are characterized in that:

1) adopting dry corn straws (with the water content of 6-12 percent by mass) as auxiliary materials, and carrying out pretreatment procedures of mechanical crushing and microbial decay on the dry corn straws:

firstly, crushing the corn straws to ensure that the straws with the grain size of more than 60 meshes reach D80 (namely, the straw particles with the grain size of less than or equal to 60 meshes reach more than 80 percent); then, adjusting the mass water content of the crushed corn straws to 75-80%, adding cellulase accounting for 0.1-0.3% of the mass of the dried corn straws and hemicellulase accounting for 0.1-0.3%, and carrying out decay for 3-5 days under the natural ventilation condition to obtain pretreated straws; mixing the pretreated straws with chicken manure according to a carbon-nitrogen ratio of 25-35: 1, adjusting to obtain a mixed material to be fermented;

2) in the initial stage, starting by a dry method (the mass water content of materials in the reactor is 70-85%), additionally preparing domesticated sludge accounting for 20-30% of the mass of the total materials for inoculation after the mixed straws and chicken manure are mixed, filling the materials into 75-80% of the total volume of the anaerobic reactor, starting a stirring device every 1-6 hours for 5-10 minutes, and maintaining the process for 3-5 days;

3) when the reactor is started quickly, the daily feeding amount is gradually increased by taking 3-5 days as an adjusting period, the initial daily feeding amount is 1% -3% of the effective volume, the daily addition amount of the materials is adjusted in a stepped manner under the conditions that the concentration of methane produced by gas is more than 35% and the pH value in the reactor is more than 6.5, the increasing amount of each adjustment is 10% -40% of the feeding amount in the previous period, and the system reaches full-load operation (namely the daily feeding amount is 4% -5% of the effective volume); the feeding amount and the discharging amount are kept consistent, so that the filling volume of the materials in the reactor is kept to be 75-80% of the total volume of the reactor (namely the effective volume is kept to be 75-80%);

4) and (3) a stabilization stage: when the system is operated at full load (namely the daily feeding amount is 4-5% of the effective volume, and the retention time is 20-25 d), the proportion of the domesticated sludge in the material of the anaerobic reactor can be stopped or reduced (the reduction refers to that only a mixture of straws and chicken manure or the mixed straws and chicken manure are additionally provided with the domesticated sludge accounting for 5-30% of the mass of the feeding material in the feeding process); and carrying out normal running operation of the system.

2. The method of claim 1, wherein:

domesticated sludge is adopted to perform inoculation in the initial stage (quick start) of reactor operation and the operation process (stabilization stage) is matched with alkali liquor to supplement alkalinity and microbial biomass; domesticated sludge (with the mass water content of 75-80%) and alkali liquor (the alkali liquor can adopt NaOH solution and the like, and the concentration of the alkali liquor is 4.0-5.0 mol/L) in a mass ratio of 1: 1-2 in proportion.

3. The method of claim 1, wherein:

a methane concentration detector is arranged at the top of the anaerobic reactor, and a pH value detector is arranged in the middle or at the bottom of the anaerobic reactor;

in one or two processes of an initial stage, a rapid start and a stabilization stage, when the methane concentration is reduced by 2% day or the pH is reduced by more than 0.4 day, the acclimated sludge (the mass water content is 75-80%) and an alkali liquor (the alkali liquor can adopt NaOH solution and the like, and the alkali liquor concentration is 4.0-5.0 mol/L) are mixed according to the mass ratio of 1: 1-2, and adjusting the pH value to ensure that the pH value is between 6.5 and 8.0;

and (3) automatically stirring after the fermentation liquor is put in, detecting the pH for the second time after 3-5 hours, and if the pH does not reach the specified range, continuously adding the alkali liquor to ensure that the pH in the fermentation liquor is maintained between 6.5 and 8.0.

4. The method of claim 1, wherein:

the anaerobic reactor adopts a zone temperature control mode; because the heat demand of each region is different in the reactor, the shell of the anaerobic reactor is sequentially and evenly divided into 3-4 regions along the material moving direction, a temperature sensor and a heating device (such as an electric heating element or a heating water pipe or a heating water jacket) are respectively arranged at the middle part and/or the bottom part of the anaerobic reactor, the real-time measurement of the temperature sensor connected with a temperature controller is carried out, the power of the heating device connected with an external power supply through the temperature controller is adjusted, or the flow of hot water is controlled by adjusting an electromagnetic valve on the heating water pipe connected with the temperature controller, so that the integral temperature of the reactor is within 37 +/-2 ℃, and the stable operation of the reactor is ensured.

5. The method of claim 1, wherein:

feeding in a bell-less manner in a reactor (figure 3), installing a bell-less at a feeding port at the upper part or the top of the anaerobic reactor, installing feeding and discharging valves at the upper end and the lower end of the bell-less, and arranging a heating device (such as one or more of a hot water coil, a heat exchanger, an electric heater and the like) and a methane blowing-off inlet and outlet on the bell-less; the biogas stripping inlet is connected with a biogas outlet at the top of the anaerobic reactor or an external nitrogen source, the feeding is preheated to 37 +/-2 ℃ by using a heating device, and the phenomenon that the local temperature change is overlarge due to the fact that cold materials enter a system and the microbial activity is reduced is avoided; the biogas generated by the reactor is used for blowing off the materials through the blowing inlet and outlet on the bell-less bell, so that oxygen in the feeding process is prevented from entering the anaerobic reactor, the safety risk is reduced, the reactor is ensured to maintain an anaerobic stable environment, and the stable operation of the reactor is ensured.

6. A method according to claim 1, 2 or 3, characterized in that:

the preparation process of the domesticated sludge comprises the following steps: firstly, the mass ratio of sludge to a mixed material to be fermented (chicken manure and pretreated corn straw) is 1: 1-4, mixing the mixture in a single tank body for domestication, adding alkali liquor (the alkali liquor can be NaOH solution and the like, and the concentration of the alkali liquor is 4.0-5.0 mol/L) according to the proportion of 10-40 mg/L according to the amount of the mixture, adjusting the pH value to 6.5-8.0, controlling the temperature for domestication of the sludge to be maintained at 37 +/-2 ℃, measuring the pH value every day, ensuring that the pH value in the sludge is always in the range of 6.5-8.0 suitable for the survival of methanogens, fully stirring for 2-5 times every day, supplementing the mixture to be fermented with equal mass once a week, and using the mixture after domestication for one week;

the sludge source is residual activated sludge of sewage plants such as municipal plants, and the mass water content is 75-80%.

Technical Field

The invention relates to a quick starting process and a stable operation method for dry fermentation of chicken manure and corn straw.

Background

As a big agricultural country, corn straw resources are abundant, the amount of the corn straw which is a main crop in the country in 2018 is 9 hundred million tons, wherein the proportion of the corn straw is more than 1/3, and the reasonable conversion of the part of resources into usable energy is very important. The animal husbandry is one of important components of agriculture, is a major post industry of agricultural production, is one of main sources of income of farmers, a large amount of corn straws and chicken manure are not effectively utilized in China at present, resource waste is caused, the anaerobic fermentation technology is an effective means for realizing resource utilization of the corn straws, and the generation of renewable energy sources such as methane gas and the like while solving the problem of corn straw waste has important significance for relieving the energy shortage condition in China, promoting sustainable development of social economy and improving ecological environment. At present, anaerobic fermentation technology adopts single materials to carry out anaerobic fermentation, and is mostly wet fermentation, but the product concentration in and after the fermentation of the independent chicken manure is lower, the energy consumption is larger, the carbon-nitrogen ratio is unbalanced, and the stability of the fermentation process is poor. And the lignin content in the corn straws is too high and is difficult to hydrolyze, so that the fermentation period is long and the efficiency of producing the biogas is low when the corn straws are used as a single material for anaerobic fermentation, and the maximum biogas engineering benefit cannot be realized. In addition, the mud output is huge among the municipal sewage treatment plant, because quality moisture content is too high in the mud, the calorific value is lower after the burning, the landfill occupies land resource again, and easily cause secondary pollution, and traditional anaerobic fermentation technical solution is too high for preventing initial stage material input volume at present, methane fungus is not enough to lead to the reactor hydrolysis acidification serious, the start failure condition appears, all select the wet process to start and guarantee steady operation, continuously adjust the material input volume afterwards until the reactor is in dry fermentation state. But the material dosage at the initial stage of wet-process start-up is less, the total solid content in the reactor is low, the reaction period is longer, and the operation efficiency of the reactor is lower. In the traditional anaerobic fermentation process, the sludge addition is only in the starting stage and when the gas production efficiency is low, the sludge addition is not distributed in the whole process, the acidification rate of acid-producing bacteria and the rate of methane-producing bacteria using volatile fatty acid can not be maintained to maintain dynamic balance, but the content of microorganisms in the sludge is high, so that sufficient strains can be provided for the anaerobic fermentation process and the alkalinity can be supplemented properly.

Therefore, the invention provides a stable dry anaerobic fermentation process which is quickly started by a dry method.

Disclosure of Invention

The invention relates to a quick starting process and a stable operation method for dry fermentation of chicken manure and corn straw. The method comprises the steps of pretreating corn straws by mechanical crushing and microbial decay, mixing the pretreated corn straws with chicken manure according to a designed optimized proportion, fermenting, and simultaneously carrying out special culture and domestication processes on residual sludge of a sewage plant to adjust the pH value of an anaerobic reactor, increase the quantity of methanogens, reduce the addition of alkali liquor at the initial stage, improve the starting speed stability and effectively improve the gas production efficiency.

A quick starting process and a stable operation method for the dry fermentation of chicken manure and corn straws,

1) adopting dry corn straws (with the water content of 6-12 percent by mass) as auxiliary materials, and carrying out pretreatment processes of mechanical crushing and microbial decay on the dry corn straws:

firstly, crushing the corn straws to ensure that the straws with the grain size of more than 60 meshes reach D80 (namely, the straw particles with the grain size of less than or equal to 60 meshes reach more than 80 percent); then, adjusting the mass water content of the crushed corn straws to 75-80%, adding cellulase accounting for 0.1-0.3% of the mass of the dried corn straws and hemicellulase accounting for 0.1-0.3%, and carrying out rotting for 3-5 days under the natural ventilation condition to obtain pretreated straws; mixing the pretreated straws with chicken manure according to a carbon-nitrogen ratio of 25-35: 1, adjusting to obtain a mixed material to be fermented;

2) in the initial stage, a dry method is adopted for starting (the mass water content of materials in the reactor is 70-85%), domesticated sludge accounting for 20-30% of the mass of the total materials is required to be additionally prepared for inoculation for the mixed straws and chicken manure, the materials are filled into 75-80% of the total volume of the anaerobic reactor, the stirring device is started every 1-6 hours for 5-10 minutes, and the process is maintained for 3-5 days;

3) when the reactor is started quickly, the daily feeding amount is gradually increased by taking 3-5 days as an adjusting period, the initial daily feeding amount is 1% -3% of the effective volume, the daily addition amount of the materials is adjusted in a stepped manner under the conditions that the concentration of methane produced by gas is more than 35% and the pH value in the reactor is more than 6.5, the increasing amount of each adjustment is 10% -40% of the feeding amount in the previous period, and the system reaches full-load operation (namely the daily feeding amount is 4% -5% of the effective volume); the feeding amount and the discharging amount are kept consistent, so that the filling volume of the materials in the reactor is kept to be 75-80% of the total volume of the reactor (namely the effective volume is kept to be 75-80%);

4) and (3) a stabilization stage: when the system is operated at full load (namely the daily feeding amount is 4-5% of the effective volume, and the retention time is 20-25 d), the proportion of the domesticated sludge in the material of the anaerobic reactor can be stopped or reduced (the reduction refers to that only a mixture of straws and chicken manure or the mixed straws and chicken manure are additionally provided with the domesticated sludge accounting for 5-30% of the mass of the feeding material in the feeding process); and carrying out normal running operation of the system.

Domesticated sludge is adopted to perform inoculation in the initial stage (quick start) of reactor operation and the operation process (stabilization stage) is matched with alkali liquor to supplement alkalinity and microbial biomass; domesticated sludge (the mass water content is 75-80%) and alkali liquor (the alkali liquor can adopt NaOH solution and the like, and the concentration of the alkali liquor is 4.0-5.0 mol/L) are mixed according to the mass ratio of 1: 1-2 in proportion.

A methane concentration detector is arranged at the top of the anaerobic reactor, and a pH value detector is arranged in the middle or at the bottom of the anaerobic reactor;

in one or two processes of an initial stage, a rapid start and a stabilization stage, when the methane concentration is reduced by 2% day or the pH is reduced by more than 0.4 day, the acclimated sludge (the mass water content is 75-80%) and an alkali liquor (the alkali liquor can adopt NaOH solution and the like, and the alkali liquor concentration is 4.0-5.0 mol/L) are mixed according to the mass ratio of 1: 1-2, and adjusting the pH value to ensure that the pH value is between 6.5 and 8.0;

and (3) automatically stirring after the fermentation liquor is put in, detecting the pH for the second time after 3-5 hours, and if the pH does not reach the specified range, continuously adding the alkali liquor to ensure that the pH in the fermentation liquor is maintained between 6.5 and 8.0.

The anaerobic reactor adopts a zone temperature control mode; because the heat requirements of all the areas in the reactor are different, the shell of the anaerobic reactor is sequentially and evenly divided into 3-4 areas along the material moving direction, a temperature sensor and a heating device (such as an electric heating element or a heating water pipe or a heating water jacket) are respectively arranged at the middle part and/or the bottom of the anaerobic reactor, the power of the heating device connected with an external power supply through a temperature controller or the flow of hot water is controlled through adjusting an electromagnetic valve on a heating water pipe connected with the temperature controller by real-time measurement of the temperature sensor in signal connection with the temperature controller, so that the overall temperature of the reactor is 37 +/-2 ℃, and the stable operation of the reactor is ensured.

Feeding in a bell-less manner in a reactor (figure 3), installing a bell-less at a feeding port at the upper part or the top of the anaerobic reactor, installing feeding and discharging valves at the upper end and the lower end of the bell-less, and arranging a heating device (such as one or more of a hot water coil, a heat exchanger, an electric heater and the like) and a methane blowing-off inlet and outlet on the bell-less; the biogas stripping inlet is connected with a biogas outlet at the top of the anaerobic reactor or an external nitrogen gas source, the feeding is preheated to 37 +/-2 ℃ by using a heating device, and the phenomenon that the local temperature change is overlarge due to the fact that cold materials enter a system and the microbial activity is reduced is avoided; the biogas generated by the reactor is used for blowing off the materials through the blowing inlet and outlet on the bell-less bell, so that oxygen in the feeding is prevented from entering the anaerobic reactor, the safety risk is reduced, the reactor is ensured to maintain an anaerobic stable environment, and the stable operation of the reactor is ensured.

The preparation process of the domesticated sludge comprises the following steps: firstly, the mass ratio of sludge to a mixed material to be fermented (chicken manure and pretreated corn straw) is 1: 1-4, mixing the mixture in a single tank body for domestication, adding alkali liquor (the alkali liquor can adopt NaOH solution and the like, and the concentration of the alkali liquor is 4.0-5.0 mol/L) according to the proportion of 10-40 mg/L according to the amount of the mixture, adjusting the pH to 6.5-8.0, controlling the temperature for domestication of the sludge to be maintained at 37 +/-2 ℃, measuring the pH every day, ensuring that the pH in the sludge is always in the range of 6.5-8.0 suitable for the survival of methanogens, fully stirring for 2-5 times every day, supplementing the mixture to be fermented with equal mass once a week, and using the mixture after domestication for one week;

the sludge source is residual activated sludge of sewage plants such as municipal plants, and the mass water content is 75-80%.

In the starting of the mixed anaerobic fermentation of the chicken manure and the corn straw, the single fermentation has the serious defects of unbalanced carbon-nitrogen nutrition ratio and the like, and is not beneficial to the application of biogas engineering. Therefore, by utilizing the advantages of the chicken manure and the corn straw, the carbon-nitrogen ratio of the chicken manure to the corn straw is 25-35: 1, the activity of acid-producing bacteria and methanogenic bacteria in the anaerobic reactor can be maintained, and the efficiency of the biogas engineering is improved.

Cellulose, hemicellulose and the like in the corn straws are not beneficial to absorption and utilization of nutrient substances in the corn straws by microorganisms, so that the corn straws are pretreated by adopting a mode of mechanical crushing and microbial decay, and the utilization rate of the nutrient substances is improved.

The novel starting mode is provided, dry-method stepped starting is selected on the basis of using mixed materials, the fermentation period can be greatly shortened, and the economy is improved.

The reactor adopts a bell-less feeding mode in the feeding mode, and is provided with a heating device and an oxygen blowing-off device, so that the stability of the internal temperature and the oxygen concentration of the reactor is ensured.

And setting the methane concentration and the pH value in the intelligent detection system monitoring system and linking with the alkali adding system.

The specially domesticated sludge is selected to replace part of alkali liquor to be added, so that extra methanogens are provided while the pH value of the fermentation system is maintained, and the anaerobic reactor can stably operate.

Activated sludge: the activated sludge is a general term for microbial communities and organic substances and inorganic substances attached to the microbial communities, wherein the microbial communities mainly comprise bacteria, protozoa, algae and the like, and the activated sludge in the patent refers to sludge in an anaerobic pool or an aerobic pool in a sewage treatment facility.

The quick starting process adopts dry starting, utilizes special culture and domesticated sludge for inoculation, simultaneously adjusts the initial pH stability of the reactor, improves the activity of methanogens, is beneficial to quick propagation increment of the methanogens, and reduces alkali liquor addition in a debugging starting period. The method realizes the rapid and stable start and the later stable operation of the dry anaerobic fermentation system.

Drawings

FIG. 1 is a flow chart of the whole process of material addition;

FIG. 2 is a flow chart of the whole system for quick start and operation of chicken manure and corn stalks;

FIG. 3 is a schematic view of a bell-less structure; wherein, 1, a bell-less feeding valve, 2, a bell-less discharging valve, 3, a bell-less water bath heating jacket (or interlayer), 4, a blow-off air valve, 5, a blow-off air inlet valve, 6, a heating system water inlet, 7 and a heating system water return;

Detailed Description

The purpose of the invention is realized as follows:

as shown in figure 2, the corn stalks used for fermentation are crushed to ensure that 60-mesh stalks reach D80, and the sludge is taken from a sewage treatment plant (the sludge is from residual biological activated sludge after dehydration, a sludge concentration tank or an anaerobic digestion tank). The mass ratio of the sludge to a mixed material to be fermented (fresh chicken manure and pretreated corn straw) before use is 1: 1-4, mixing in a separate tank body for domestication, adding alkali liquor to adjust the pH value to 6.5-8.0, controlling the temperature for domestication of the sludge to be maintained at 37 +/-2 ℃, measuring the pH value every day, ensuring that the pH value in the sludge is always in the range of 6.5-8.0 suitable for the survival of methanogens, fully stirring three times every day, supplementing once a week a mixed material to be fermented with equal mass, and domesticating for one week for use. The mixed material of the chicken manure and the corn straw is added with partial alkali liquor and domesticated sludge every day according to the change of pH and methane concentration in the initial stage and the starting stage, so that the stability of pH and the sufficient quantity of microorganisms are ensured. The test whole period adopts the equivalent feeding and equivalent discharging means, and because the material adding and discharging amount in the stable stage is large, in order to prevent the microorganism in the fermentation reactor from losing, a method of supplementing and domesticating sludge is adopted, so that the high-yield methane efficiency can be maintained, and the methane can be discharged in an equivalent mannerThe decomposition and utilization efficiency of the thrown materials is improved. And performing secondary aerobic composting on the materials discharged in the initial stage, the starting stage and the stabilizing stage. The intelligent detection system is arranged for ensuring the rapid and stable operation of the anaerobic fermentation process, a pH real-time online detection instrument is set for ensuring the stability of the pH in the anaerobic reactor, and when the pH is detected to be not between 6.5 and 8.0 through the control system and the regulation and control system, the adding amount of the alkali liquor and the domesticated sludge can be automatically calculated to ensure the stability of the pH. The temperature sensors arranged in the anaerobic reactor feed back the temperatures in different regions and adjust the power of the heating device, so as to ensure that the integral temperature of the anaerobic reactor is 37 +/-2 ℃. A marsh gas treatment device (dehydration, desulfurization and the like) is adopted at the marsh gas collection part to treat H in the gas₂Separating S from water and the like to ensure that high-purity CH is obtained₄The change of the methane concentration can be fed back to the central control system in real time, and the feeding amount of the acclimatized sludge is properly adjusted according to the change of the methane concentration.