Method for treating solid residue of kitchen waste by in-situ enzyme production and micro-aeration tidal percolation bed

Abstract

The invention discloses a method for treating solid residues of food waste by in-situ enzyme production and micro-aerated tidal percolation beds. The organic solid residues separated after the hydrothermal treatment of food waste are mixed with wood chips and microbial agents, and then in-situ enzyme production is carried out under certain ventilation conditions. After in-situ enzyme production, the substrate is soaked with tap water to obtain an immersion solution rich in self-produced enzymes, and the remaining substrate after enzyme production is subjected to post-treatment. Another part is mixed with wood chips and activated sludge and subjected to tidal percolation fermentation (anaerobic fermentation) with the self-produced enzyme immersion solution, and at the same time, micro-aeration with air is supplemented to promote microbial activity, and the remaining substrate after fermentation is subjected to post-treatment. The invention relates to the technical field of food waste treatment. The method for treating solid residues of food waste by in-situ enzyme production and micro-aerated tidal percolation beds couples the in-situ enzyme production of solid residues of food waste with the anaerobic fermentation process, ensuring the treatment capacity of solid residues of food waste while realizing the reduction and resource utilization of solid residues of food waste, and providing a new treatment idea for solid residues of food waste.

Description

Technical Field

[0001] The present invention relates to the technical field of kitchen waste treatment, and specifically to a method for treating kitchen waste solid residue by in-situ enzyme production and micro-aeration tidal percolation bed. Background Technique

[0002] Anaerobic digestion is the mainstream treatment process for kitchen waste at present. However, in some kitchen waste treatment plants, after the kitchen waste undergoes hydrothermal treatment, three-phase separation is carried out. The liquid phase is used for anaerobic fermentation in a completely mixed anaerobic reactor (CSTR), the oil phase is used for recycling, and the solid residue (about 15-20% of the total kitchen waste) will significantly increase the operating load of the CSTR due to its high solid content. This not only increases the operating cost and time, but also leads to an increase in the production of biogas residue. At the same time, it is not conducive to the stability of the reaction and there is also a risk of blockage. Therefore, the solid residue is usually treated by harmless treatment methods such as incineration or landfill.

[0003] At present, the research mainly focuses on two-phase anaerobic reactors (leaching bed + upflow anaerobic sludge bed) for large-particle-size kitchen waste (>4-10 mm). Such reactors can cultivate different microorganisms respectively, thereby improving the overall process efficiency. The leaching bed (LBR) reactor realizes the efficient hydrolysis and acidification of kitchen waste, and the upflow anaerobic sludge bed (UASB) reactor realizes the efficient methane production from the acidified liquid. In addition, the leaching bed can adapt to kitchen waste with a high solid content, and the UASB has the advantages of high operating load and high reaction rate. However, these studies have not involved the delicate and viscous kitchen waste solid residue (<2 mm), and the LBR has problems such as uneven leaching and easy blockage.

[0004] In addition, although the solid residue is rich in organic matter, the organic matter is mainly composed of macromolecular starch, protein and cellulose, which are difficult to be utilized by microorganisms in a short time. Therefore, how to efficiently produce methane from kitchen waste solid residue, accelerate the reaction rate, and realize the efficient resource utilization of the solid residue is worthy of attention. Summary of the Invention

[0005] (I) Technical Problems to be Solved

[0006] In view of the deficiencies of the prior art, the present invention provides a method for treating kitchen waste solid residue by in-situ enzyme production and micro-aeration tidal percolation bed, which resourcefully treats the kitchen waste solid residue and improves the overall resource utilization rate of kitchen waste. By using the kitchen waste solid residue for in-situ enzyme production treatment, the treatment amount of the kitchen waste solid residue is ensured. At the same time, coupling in-situ enzyme production with anaerobic fermentation, on the one hand, the enzymes produced by in-situ enzyme production from the kitchen waste solid residue accelerate the efficiency of anaerobic fermentation, and on the other hand, the organic matter in in-situ enzyme production is introduced into anaerobic fermentation, increasing the content of organic matter in anaerobic fermentation, which is beneficial to increasing the methane production, and realizing more efficient reduction, resource utilization and harmless treatment of kitchen waste solid residue.

[0007] (2) Technical Solution

[0008] To achieve the above object, the present invention is realized through the following technical solutions: a method for treating solid residues of food waste by in-situ enzyme production and micro-aeration tidal percolation beds. Using the organic solid residues separated after the hydrothermal treatment of food waste as raw materials, it is treated by the coupling method of in-situ enzyme production and anaerobic fermentation to achieve the purpose of reduction and resource utilization. The specific steps are as follows:

[0009] S1. After the food waste is sorted, crushed, and decontaminated, the slurry is heated in a high-pressure sterilization tank at 100 - 130 °C for 60 - 180 min. After the three-phase separation of the slurry, the solid residues are respectively subjected to in-situ enzyme production and tidal percolation fermentation;

[0010] S2. For in-situ enzyme production, the solid residues, wood chips, and microbial agents are mixed and filled into a columnar nylon bag with 80 - 100 meshes, and fermented at 25 - 55 °C for 6 d. Internal mechanical stirring is used to achieve the effect of turning the pile to increase the microbial activity;

[0011] S3. After 3 d of in-situ enzyme production, an appropriate amount of tap water is slowly added from the upper part of the fermentation device. During this period, the mechanical stirring is stopped. After soaking, the drain port is opened, and the residual water is filtered out through the lower filter plate. After continuing the in-situ enzyme production for 3 d, 20% of the remaining substrate is used as the inoculum for the next fermentation, and the rest of the remaining substrate is subjected to post-treatment;

[0012] S4. For tidal percolation fermentation, the solid residues, wood chips, and preheated inoculated sludge are mixed and filled into a columnar nylon bag with 80 - 100 meshes, and fermented at 55 °C for 6 d. The soaking solution produced by in-situ enzyme production is slowly poured over the pile from the bottom. After soaking for a period of time, it is discharged from the bottom to the leachate storage tank. The pH of the leachate is adjusted by sodium carbonate or sodium bicarbonate. During the non-soaking period, micro-aeration is used to increase the microbial activity and accelerate the hydrolysis process of the solid residues; 20% of the remaining substrate is used as the inoculum for the next fermentation, and the rest of the remaining substrate still undergoes post-treatment. The leachate is used for methane production in UASB, and the UASB effluent is used for in-situ enzyme production soaking or directly discharged;

[0013] Preferably, the food waste in step S1 is high-solid food residues collected centrally by the municipality, excluding the residues from food processing plants. The solid residue is the solid phase after hydrothermal treatment at 100 - 130 °C and three-phase separation for oil removal at 2000 - 3000 rpm, and TS ≥ 20%.

[0014] Preferably, 10 - 20% by mass of wood chips and 1 - 10% by mass of microbial agents are added to the solid residues in step S2, mixed evenly, filled into a columnar nylon bag with 80 - 100 meshes, and under the ventilation condition of 0.5 - 1 L / min of air, the internal mechanical stirring is 30 - 60 rpm, and the outside is wrapped with heat-insulating cotton to reduce heat loss.

[0015] Preferably, the bacterial agent includes but is not limited to EM bacterial agent, Bacillus subtilis, Aspergillus awamori, Aspergillus oryzae, and Aspergillus niger.

[0016] Preferably, in step S3, the next batch of experiments uses 20% of the remaining substrate from the previous batch of experiments as the inoculum, and adds the same amount of kitchen waste solid residue as in the previous batch of experiments, 80% of wood chips, and 50% of the bacterial agent. Repeat the operation. Finally, the SCOD of the soaking solution in each batch of experiments is 2400 mg / L, TN is 175 mg / L, and the VS removal rate of the overall solid residue is 21.5%.

[0017] Preferably, after 3 days of in-situ enzyme production in step S3, tap water is added from the top of the device to submerge the in-situ enzyme production volume by ≥80%. After soaking for 10 - 30 minutes, open the drain port and drip-filter the residual water in the in-situ enzyme production for 1 - 8 hours. The pore diameter of the bottom filter plate is ≤1 mm. During this period, both ventilation and mechanical stirring are turned off. After drip-filtering, continue in-situ enzyme production for 3 days to degrade the remaining organic matter to achieve the effect of reduction.

[0018] Preferably, 10 - 20% by mass of wood chips and 10 - 20% by mass of inoculated sludge are added to the solid residue in step S4. The inoculated sludge is subjected to a water bath at 75°C for 15 minutes and centrifuged at 3000 - 4000 r for 15 minutes, and then inoculated with the bottom precipitate after centrifugation and packed into a columnar nylon bag with 80 - 100 meshes.

[0019] Preferably, the mass ratio of the solid residue to the in-situ enzyme production soaking solution in step S4 is 1:(2.5 - 5), and it is soaked in a tidal manner every 6 - 12 hours. The pore diameter of the bottom filter plate is ≤1 mm. After the leachate completely submerges the pile body and soaks for 1 - 2 hours, it is discharged into the leachate storage tank, the pH is adjusted to 6 - 8, the temperature is controlled at 50 - 55°C, and air micro-aeration operation is carried out for 10 minutes every 12 hours. The micro-aeration rate is 2.5 - 4 L 空气 / kg 固渣 , when the TCOD of the leachate > 8000 mg / L, 25% of the leachate is discharged for methane production in UASB, and 75% of the leachate is discharged for methane production in UASB on the last day. The next batch of experiments uses 20% of the remaining substrate from the previous batch of experiments as the inoculum, adds the same amount of kitchen waste solid residue as in the previous batch of experiments, the same amount of centrifuged and preheated anaerobic sludge, and 80% of wood chips, and mixes the remaining 25% of the leachate from the previous batch of experiments with the in-situ enzyme production soaking solution for tidal soaking operation, and repeat the operation. The UASB is inoculated with anaerobic granular sludge, and the inoculation ratio is gTCOD 酸化液 : gVS 颗粒污泥 = 0.5 - 1, and the UASB effluent is recycled to the in-situ enzyme production reactor for pile body soaking or directly discharged to the sewage treatment plant.

[0020] Preferably, both the in-situ enzyme production and the anaerobic fermentation cycle are 6 days. First, in-situ enzyme production is carried out for 3 days to obtain an immersion liquid rich in self-produced enzymes, and then anaerobic fermentation is initiated. On the 3rd day of anaerobic fermentation, the in-situ enzyme production enters the next batch of experiments. On the 6th day of anaerobic fermentation, a tidal immersion operation is carried out using the immersion liquid produced by the second batch of in-situ enzyme production, realizing the continuous repetition of the two experimental cycles.

[0021] (III) Beneficial effects

[0022] The present invention provides a method for treating kitchen waste solid residue by in-situ enzyme production and micro-aerated tidal filtration bed. Compared with the prior art, it has the following beneficial effects:

[0023] (1) The method for treating kitchen waste solid residue by in-situ enzyme production and micro-aerated tidal filtration bed can rapidly produce enzymes by in-situ enzyme production of kitchen waste solid residue, and extract enzymes by soaking with tap water, thereby improving the initial hydrolysis efficiency of the tidal filtration bed; micro-aeration promotes the microbial activity and accelerates the process of anaerobic fermentation hydrolysis and acid production; the remaining substrates of in-situ enzyme production and anaerobic fermentation are used for subsequent treatment to further decompose organic matter, realizing the coupled treatment of reduction and resource utilization of kitchen waste solid residue. This method uses the discarded kitchen waste solid residue for resource utilization, turning waste into treasure, improving the degree of resource utilization of kitchen waste, applying self-produced enzymes to the tidal filtration bed, accelerating the initial hydrolysis efficiency of kitchen waste solid residue, shortening the treatment time, and improving the treatment efficiency.

[0024] (2) The method for treating kitchen waste solid residue by in-situ enzyme production and micro-aerated tidal filtration bed, by applying micro-aeration to the tidal filtration bed, accelerates the hydrolysis efficiency of the solid residue, shortens the treatment time, and improves the treatment efficiency; couples in-situ enzyme production with anaerobic fermentation, rapidly produces enzymes under aerobic conditions, and provides part of the organic matter to anaerobic fermentation, reducing the loss of organic matter during in-situ enzyme production, and at the same time accelerating the process of anaerobic fermentation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is the process flow chart of the present invention;

[0026] Figure 2 is the specific schematic diagram of the coupled process of in-situ enzyme production and anaerobic fermentation of the present invention.

[0027] In the figure, 1 is the heat and humidity treatment unit; 2 is the in-situ enzyme production reactor; 5 is the micro-aerated tidal filtration bed; 6 is the UASB for methane production. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] Please refer to Figure 1-2 , the embodiments of the present invention provide two technical solutions: a method for treating kitchen waste solid residue by in-situ enzyme production and micro-aeration tidal filtration bed, specifically including the following embodiments:

[0030] Example 1:

[0031] As Figure 2 shown, the present invention is a method for coupling in-situ enzyme production and micro-aeration tidal filtration bed to treat kitchen waste solid residue, including a wet heat treatment unit 1, an in-situ enzyme production reactor 2, a micro-aeration tidal filtration bed 5, and a UASB methane production 6. The present invention can accelerate the hydrolysis and acidification of organic matter in kitchen waste solid residue, produce highly acidified organic fermentation liquor suitable for treatment by high-efficiency anaerobic reactors such as UASB, and realize the efficient resource utilization of kitchen waste solid residue. The steps include:

[0032] (1) In the wet heat treatment unit 1, the slurry of kitchen waste after sorting, crushing, and impurity removal is heated in an autoclave at 120°C for 60 min, then centrifuged at 3000 r for 15 min, and the bottom solid residue is taken for subsequent reactions.

[0033] (2) In the in-situ enzyme production reactor 2, 150 g of kitchen waste solid residue (TS = 22.59%, VS = 20.86%) is taken, 22.5 g of wood chips and 7.5 g of EM bacterial agent are added, and after mixing evenly, it is added into an 80-mesh columnar nylon bag (volume 1 L). The nylon bag is placed on the 1-mm filter plate 4 of the reactor. Under the conditions of a ventilation rate of 0.5 L / min and a mechanical stirring speed of 30 rpm, after running at 37°C for 3 d, aeration and stirring are stopped, and it is soaked with 0.75 L of tap water for 30 min. Then the drain port is opened, and the residual water in the heap is drip-filtered for 6 h to obtain an immersion liquid rich in self-produced enzymes. After drip-filtration, fermentation is continued for 3 d to further degrade organic matter, achieving the effect of rapid reduction in quantity. For the next batch of experiments, 20% of the remaining substrate from the previous batch of experiments is used as the inoculum, 150 g of kitchen waste solid residue is added, 18 g of wood chips and 3.75 g of bacterial agent are added, and the operation is repeated. Finally, the SCOD of the immersion liquid in each batch of experiments is 2400 mg / L, TN is 175 mg / L, and the VS removal rate of the whole solid residue is 21.5%.

[0034] (3) In the micro-aerated tidal leaching bed 5, 200 g of kitchen waste solid residue (TS = 22.59%, VS = 20.86%) was taken, 30 g of wood chips and 3 g of centrifuged anaerobic sludge preheated at 75 °C for 15 min were added. After mixing evenly, it was added into an 80-mesh columnar nylon bag (volume 1 L), and the nylon bag was placed on the 1-mm filter plate of the reactor. Every 12 h, 1 L of the soaking solution produced on the 3rd day in step 2 (diluted with 250 mL of tap water) was used for the tidal soaking of the pile body. After soaking for 1 - 2 h, it was drained into the leachate storage tank. Before the second soaking, the pH of the leachate was adjusted to 6 in the leachate storage tank. If the pH of the leachate was between 6 - 8, no adjustment was made. 4 h after the end of the first soaking, air was aerated at a rate of 2.5 L 空气 / kg 固渣 for 10 min to promote the growth of microorganisms. When the TCOD of the leachate > 8000 mg / L, 25% of the leachate was discharged for methane production, and 75% of the leachate was discharged for methane production on the 6th day. For the next batch of experiments, 20% of the remaining substrate from the previous batch of experiments was used as the inoculum, 200 g of kitchen waste solid residue was added, 24 g of wood chips and 3 g of centrifuged anaerobic sludge preheated at 75 °C for 15 min were added. The remaining 25% of the leachate was mixed with the soaking solution in step 2 for the tidal soaking operation, and the operation was repeated. Finally, in each batch of experiments on the 3rd and 5th days, the TCOD of the leachate > 8000 mg / L, and a total of 500 mL of leachate was discharged; on the 6th day, 750 mL of leachate was discharged, and the TCOD of the leachate = 8098 mg / L, SCOD = 7963 mg / L, ammonia nitrogen = 428 mg / L, and the overall hydrolysis yield of the kitchen waste solid residue reached 310 g cum.SCOD / kg VS added , and the overall acidification yield reached 230 g cum.SCOD / kg VS added .

[0035] (4) The in-situ enzyme production and the tidal leaching fermentation (anaerobic fermentation) cycle were both 6 days. First, in-situ enzyme production was carried out for 3 days to obtain a soaking solution rich in self-produced enzymes, and then anaerobic fermentation was started. On the 3rd day of anaerobic fermentation, the in-situ enzyme production entered the next batch of experiments; while on the 6th day of anaerobic fermentation, the tidal soaking operation was carried out with the soaking solution produced by the second batch of in-situ enzyme production, realizing the continuous repetition of the experimental cycles of both.

[0036] (5) In UASB for methane production 6, the leachate (acidified liquid) produced in step 3 was inoculated at a ratio of gCOD 酸化液 :gVS 颗粒污泥 = 1, and part of tap water was added to adjust the initial SCOD concentration = 5000 mg / L. After running for 4 days. Finally, the cumulative methane production rate of the acidified liquid in each batch of experiments reached 307.06 mL CH4 / gTCOD 酸化液 , and the cumulative gas production reached 19.2 m 3 / t餐厨垃圾固渣 and the SCOD removal rate is above 95%.

[0037] (6) The remaining substrates generated by in-situ enzyme production and anaerobic fermentation are both subjected to post-treatment.

[0038] Example 2:

[0039] A method for treating solid residues of food waste by in-situ enzyme production and micro-aerated tidal percolation bed. Using the organic solid residues separated after the hydrothermal treatment of food waste as raw materials, it is treated by the coupling method of in-situ enzyme production and tidal percolation fermentation (anaerobic fermentation) to achieve the purpose of reduction and resource utilization. The specific steps are as follows:

[0040] S1. After the food waste is sorted, crushed, and impurity-removed, the slurry is heated in a high-pressure sterilization tank at 100 °C for 60 min. After the three-phase separation of the slurry, the solid residues are respectively subjected to in-situ enzyme production and tidal percolation fermentation;

[0041] S2. For in-situ enzyme production, the solid residues, wood chips, and microbial agents are mixed and filled into an 80-mesh columnar nylon bag, and fermented at 25 °C for 3 d. Internal mechanical stirring is used to achieve the effect of turning the pile to increase the microbial activity;

[0042] S3. After 3 d of in-situ enzyme production, an appropriate amount of tap water is slowly added from the top of the fermentation device. During this period, the mechanical stirring is stopped. After soaking, the drain port is opened, and the residual water is filtered out through the lower filter plate. Continue in-situ enzyme production for 3 d. 20% of the remaining substrate is used as the inoculum for the next fermentation, and the rest of the remaining substrate is subjected to post-treatment;

[0043] S4. For tidal percolation fermentation, the solid residues, wood chips, and preheated inoculated sludge are mixed and filled into an 80-mesh columnar nylon bag, and fermented at 55 °C for 6 d. The soaking solution produced by in-situ enzyme production is slowly poured over the pile from the bottom. After soaking for a period of time, it is discharged from the bottom to the leachate storage tank. The pH of the leachate is controlled by sodium carbonate or sodium bicarbonate. During the non-soaking period, micro-aeration is used to increase the microbial activity and accelerate the hydrolysis process of the solid residues; 20% of the remaining substrate is used as the inoculum for the next fermentation, and the rest of the remaining substrate is still subjected to post-treatment. The leachate is used for methane production in UASB, and the UASB effluent is used for in-situ enzyme production soaking or directly discharged;

[0044] In the embodiment of the present invention, in step S1, the food waste is high-solid food residues collected centrally in the city, excluding the residues processed by food processing factories. The solid residue is the solid phase after hydrothermal treatment at 100 °C and three-phase separation at 2000 rpm to remove oil, and TS≥20%.

[0045] In the embodiment of the present invention, 10-20% by mass of wood chips and 1% by mass of microbial agents are added to the solid residue, mixed evenly, and filled into an 80-mesh columnar nylon bag. Under the ventilation condition of 0.5 L / min of air, mechanical stirring is carried out inside at 30 rpm, and heat insulation cotton is wrapped outside to reduce heat loss. The microbial agents include but are not limited to EM microbial agents, Bacillus subtilis, Aspergillus awamori, Aspergillus oryzae, and Aspergillus niger.

[0046] In the embodiment of the present invention, after 3 days of in-situ enzyme production in step S3, tap water is added from the top of the device to submerge the in-situ enzyme production volume by ≥80%. After soaking for 10 minutes, the drain port is opened, and the residual water in the in-situ enzyme production is drip-filtered for 1 hour. The pore diameter of the bottom filter plate is ≤1 mm. During this period, both ventilation and mechanical stirring are turned off. After drip-filtering, continue in-situ enzyme production for 3 days to continue degrading organic matter to achieve the effect of reduction.

[0047] In the embodiment of the present invention, 10% by mass of wood chips and 10% by mass of inoculated sludge are added to the solid residue. The inoculated sludge is subjected to a water bath at 75 °C for 15 minutes and centrifuged at 3000 r for 15 minutes, and then inoculated with the bottom precipitate after centrifugation and filled into an 80-mesh columnar nylon bag. The mass ratio of the in-situ enzyme production soaking solution of the solid residue = 1:2.5, and it is soaked in a tidal manner every 6 hours. The pore diameter of the bottom filter plate is ≤1 mm. After the leachate completely submerges the heap and soaks for 1 hour, it is discharged into the leachate storage tank, the pH is adjusted to 6, the temperature is controlled at 50 °C, and aeration is carried out for 10 minutes every 12 hours with an air micro-aeration rate = 2.5 L 空气 / kg 固渣 , when the TCOD of the leachate > 8000 mg / L, 25% of the leachate is discharged for methane production in UASB. On the last day, 75% of the leachate is discharged for methane production in UASB, and the remaining 25% of the leachate is mixed with the in-situ enzyme production soaking solution for the next tidal soaking operation. The UASB is inoculated with anaerobic granular sludge, and the inoculation ratio is gTCOD 酸化液 :gVS 颗粒污泥 = 0.5. The effluent of UASB is refluxed to the in-situ enzyme production reactor for heap soaking or directly discharged to the sewage treatment plant.

[0048] In the embodiment of the present invention, both the in-situ enzyme production and the anaerobic fermentation cycle are 6 days. First, in-situ enzyme production is carried out for 3 days to obtain an immersion solution rich in self-produced enzymes, and then anaerobic fermentation is started. On the 3rd day of anaerobic fermentation, in-situ enzyme production enters the next batch of experiments. On the 6th day of anaerobic fermentation, the immersion solution produced by the second batch of in-situ enzyme production is used for tidal soaking operation to realize the continuous repetition of the two experimental cycles.

[0049] In summary, the present invention rapidly produces enzymes by utilizing the in-situ enzyme production of kitchen waste solid residues, and extracts the enzymes by soaking with tap water, thereby improving the initial hydrolysis efficiency of the tidal filtration bed; promotes microbial activity through micro-aeration and accelerates the process of anaerobic fermentation hydrolysis and acid production; the in-situ enzyme production and the remaining substrates of anaerobic fermentation are used for subsequent treatment to further decompose organic matter, realizing the coupled treatment of reduction and resource utilization of kitchen waste solid residues. Using the discarded kitchen waste solid residues for resource treatment realizes turning waste into treasure, improves the degree of resource utilization of kitchen waste, applies the self-produced enzymes to the tidal filtration bed, accelerates the initial hydrolysis efficiency of kitchen waste solid residues, shortens the treatment time, and improves the treatment efficiency. By applying micro-aeration to the tidal filtration bed, the hydrolysis efficiency of solid residues is accelerated, the treatment time is shortened, and the treatment efficiency is improved; coupling in-situ enzyme production and anaerobic fermentation, rapidly producing enzymes under aerobic conditions, and providing some organic matter to anaerobic fermentation, reducing the loss of organic matter in in-situ enzyme production, and at the same time accelerating the process of anaerobic fermentation.

[0050] Meanwhile, the content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

[0051] It should be noted that, in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or sequence between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0052] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for treating solid residues of kitchen waste by in-situ enzyme production and micro-aeration tidal percolation bed, characterized in that: The organic solid residue separated from the kitchen waste after wet heat treatment is used as raw material and treated by the coupling method of in-situ enzyme production and tidal percolation fermentation. The specific steps are as follows: S1. After the kitchen waste is sorted, crushed and impurities removed, the slurry is heated in a high pressure sterilization tank at 100-130°C for 60-180 minutes. After the three phases of the slurry are separated, the solid residue is subjected to in-situ enzyme production and tidal percolation fermentation respectively; S2, in-situ enzyme production: solid residue, sawdust and bacterial agent are mixed and packed into 80-100 mesh columnar nylon bags, fermented at 25-55℃ for 6 days, and internal mechanical stirring is used to achieve the effect of turning the pile to increase the activity of microorganisms; S3, after 3 days of in situ enzyme production, slowly add an appropriate amount of tap water from the top of the fermentation device, stop mechanical stirring during the period, and after soaking, open the drain port to filter out the residual water through the lower filter plate. After continuing to produce enzymes in situ for 3 days, 20% of the remaining substrate will serve as the inoculum for the next fermentation, and the remaining substrate will be processed at the back end; S4, tidal percolation fermentation: solid residue, sawdust and preheated inoculated sludge are mixed and packed into 80-100 mesh columnar nylon bags, fermented at 55℃ for 6 days, and the soaking liquid produced by in-situ enzyme production slowly covers the pile from the bottom. After soaking for a period of time, it is discharged from the bottom to the leachate storage tank, and the enzyme is extracted by soaking in tap water to improve the initial hydrolysis efficiency of the tidal percolation bed. The pH of the leachate is adjusted by sodium carbonate or sodium bicarbonate. Micro-aeration is used during the non-immersion period to increase microbial activity and accelerate the hydrolysis process of solid residue; Tidal soaking is carried out every 6-12 hours, and 20% of the remaining substrate serves as the inoculum for the next fermentation. The remaining substrate is still subjected to back-end treatment. The leachate is used for UASB methanogenesis, and the UASB effluent is used for in situ enzyme soaking or direct discharge.

2. The method for treating solid residues of kitchen waste by in-situ enzyme production and micro-aeration tidal percolation bed according to claim 1, characterized in that: The kitchen waste in step S1 refers to high-solid catering residues collected by the municipal government, excluding residues from food processing plants, and the solid residue is the solid phase after wet heat treatment at 100-130°C and three-phase separation and oil removal at 2000-3000 rpm.

3. The method for treating solid residues of kitchen waste by in-situ enzyme production and micro-aeration tidal percolation bed according to claim 1, characterized in that: In the step S2, 10-20% by mass of sawdust and 1-10% by mass of bacterial agent are added to the solid residue, mixed evenly, and loaded into a 80-100 mesh columnar nylon bag. Under the ventilation condition of 0.5-1 L / min air, the bag is mechanically stirred at 30-60 rpm and wrapped with heat insulation cotton to reduce heat loss.

4. The method for treating solid residues of kitchen waste by in-situ enzyme production and micro-aeration tidal percolation bed according to claim 3, characterized in that: The bacterial agents include but are not limited to EM bacterial agents, Bacillus subtilis, Aspergillus awamori, Aspergillus oryzae and Aspergillus niger.

5. The method for treating solid residues of kitchen waste by in-situ enzyme production and micro-aeration tidal percolation bed according to claim 1, characterized in that: In step S3, the next batch of experiments uses 20% of the remaining substrate from the previous batch of experiments as inoculum, and adds the same amount of solid food waste residue, 80% of sawdust and 50% of bacterial agent as the previous batch of experiments, and repeats the operation.

6. The method for treating solid residues of kitchen waste by in-situ enzyme production and micro-aeration tidal percolation bed according to claim 1, characterized in that: After the in situ enzyme production for 3 days in step S3, tap water is added from the top of the device to cover the volume of the in situ enzyme production by ≥80%. After soaking for 10-30 minutes, the drain port is opened and the residual water in the in situ enzyme production is drip filtered for 1-8 hours. The pore size of the bottom filter plate is ≤1mm. During this period, ventilation and mechanical stirring are closed. After drip filtration, the in situ enzyme production is continued for 3 days to degrade the remaining organic matter.

7. The method for treating solid residues of kitchen waste by in-situ enzyme production and micro-aeration tidal percolation bed according to claim 1, characterized in that: In step S4, 10-20% by mass of sawdust and 10-20% by mass of inoculated sludge are added to the solid residue. The inoculated sludge is placed in a 75°C water bath for 15 min and centrifuged at 3000-4000 r for 15 min. The bottom sediment after centrifugation is inoculated and packed into a 80-100 mesh columnar nylon bag.

8. The method for treating solid residues of kitchen waste by in-situ enzyme production and micro-aeration tidal percolation bed according to claim 7, characterized in that: In step S4, the mass ratio of solid residue to in-situ enzyme soaking liquid is 1: (2.5-5), the pore size of the bottom filter plate is ≤1mm, the leachate is completely submerged in the pile and fully soaked for 1-2 hours before being discharged into the leachate storage tank, the pH is adjusted to 6-8, the temperature is controlled at 50-55°C, and air micro-aeration operation is performed for 10 minutes every 12 hours, and the micro-aeration rate is 2.5-4 L 空气 / kg 固渣 When the TCOD of the leachate was greater than 8000 mg / L, 25% of the leachate was discharged for UASB methanogenesis. On the last day, 75% of the leachate was discharged for UASB methanogenesis. The next batch of experiments used 20% of the remaining substrate from the previous batch of experiments as inoculum, added the same amount of solid food waste, the same amount of centrifugal preheated anaerobic sludge and 80% of sawdust as the previous batch of experiments, and mixed the remaining 25% of the leachate from the previous batch of experiments with the in situ enzyme soaking solution for tidal soaking operation. The operation was repeated, and UASB was inoculated with anaerobic granular sludge at an inoculation ratio of gTCOD. 酸化液 :gVS 颗粒污泥 =0.5-1, UASB effluent is returned to the in-situ enzyme production reactor for pile soaking or directly discharged to the sewage treatment plant.

9. The method for treating solid residues of kitchen waste by in-situ enzyme production and micro-aeration tidal percolation bed according to claim 1, characterized in that: The cycles of in situ enzyme production and anaerobic fermentation were both 6 days. First, in situ enzyme production was carried out for 3 days to obtain a soaking solution rich in self-produced enzymes, and then anaerobic fermentation was started. On the 3rd day of anaerobic fermentation, in situ enzyme production entered the next batch of experiments. On the 6th day of anaerobic fermentation, a tidal soaking operation was carried out with the soaking solution produced by the second batch of in situ enzyme production to achieve continuous repetition of the two experimental cycles.

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