Method for treating kitchen waste solid residues through in-situ enzyme production and micro-aeration tidal infiltration bed

Abstract

The invention discloses a method for treating kitchen waste solid residues through in-situ enzyme production and a micro-aeration tidal percolation bed, which comprises the following steps: mixing a part of organic solid residues separated after heat-moisture treatment of kitchen waste with sawdust and a microbial inoculum, carrying out in-situ enzyme production under a certain ventilation condition, soaking a substrate in tap water after in-situ enzyme production, and carrying out in-situ enzyme production; obtaining a soak solution rich in self-produced enzyme, and carrying out back-end treatment on the residual substrate after enzyme production; and mixing the other part with wood chips and activated sludge, carrying out tidal percolation fermentation (anaerobic fermentation) by using a self-produced enzyme soaking solution, simultaneously promoting microbial activity under the assistance of air micro-aeration, and carrying out rear-end treatment on the residual substrate after fermentation. The invention relates to the technical field of kitchen waste treatment. According to the method for treating the kitchen waste solid residues through the in-situ enzyme production and the micro-aeration tide type percolation bed, the in-situ enzyme production of the kitchen waste solid residues and the anaerobic fermentation technology are coupled, the treatment amount of the kitchen waste solid residues is guaranteed, meanwhile, reduction and resource utilization of the kitchen waste solid residues are achieved, and a new treatment thought is provided for the kitchen waste solid residues.

Description

Technical Field

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

[0002] Anaerobic digestion is the mainstream treatment process for food waste at present. However, some food waste treatment plants separate the three phases of food waste after wet heat treatment. The liquid phase is used for anaerobic fermentation in a fully mixed anaerobic reactor (CSTR), and the oil phase is used for recycling. The solid residue (accounting for about 15-20% of the total food waste) will greatly increase the operating load of the CSTR due to its high solid content, which not only increases the operating cost and time, but also leads to an increase in the production of biogas residue, which is not conducive to the stability of the reaction and also has the risk of blockage. Therefore, the solid residue is usually treated harmlessly by incineration or landfill.

[0003] At present, the research focuses on two-phase anaerobic reactors (leaching bed + upflow anaerobic sludge blanket) for large-particle food waste (>4-10mm), which can cultivate different microorganisms separately, thereby improving the overall process efficiency. The leaching bed (LBR) reactor achieves efficient hydrolysis and acidification of food waste, while the upflow anaerobic sludge blanket (UASB) reactor achieves efficient methane production from the acidified liquid. In addition, the leaching bed can adapt to high-solid food waste, and the UASB has the advantages of high operating load and high reaction rate. However, these studies have not yet involved fine and viscous food waste solid residues (<2mm), and the LBR has problems such as uneven leaching and easy clogging.

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

[0005] 1. Technical issues to be resolved

[0006] In view of the deficiencies of the prior art, the present invention provides a method for treating solid residues of kitchen waste by in-situ enzyme production and micro-aeration tidal percolation bed, which processes the solid residues of kitchen waste as resources and improves the overall resource utilization rate of kitchen waste. By using the solid residues of kitchen waste for in-situ enzyme production, the processing amount of the solid residues of kitchen waste is guaranteed. At the same time, the in-situ enzyme production is coupled with anaerobic fermentation. On the one hand, the efficiency of anaerobic fermentation is accelerated by the enzyme produced by the in-situ enzyme production of the solid residues of kitchen waste. On the other hand, the organic matter in the in-situ enzyme production is introduced into the anaerobic fermentation, which increases the content of organic matter in the anaerobic fermentation, is conducive to increasing the production of methane, and realizes more efficient reduction, resource utilization and harmless treatment of the solid residues of kitchen waste.

[0007] (II) Technical solution

[0008] To achieve the above objectives, the present invention is implemented by the following technical scheme: a method for treating solid residues of kitchen waste by in-situ enzyme production and micro-aeration tidal percolation bed, using organic solid residues separated from kitchen waste after wet heat treatment as raw materials, and treating them by in-situ enzyme production and anaerobic fermentation coupling method to achieve the purpose of reduction and resource utilization, and the specific steps are as follows:

[0009] 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;

[0010] 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;

[0011] 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;

[0012] S4, tidal percolation fermentation uses solid residue, sawdust and preheated inoculated sludge 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 leachate pH 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; 20% of the remaining substrate serves as the inoculum for the next fermentation, and the remaining remaining substrate is still processed at the back end. The leachate is used for UASB methane production, and the UASB effluent is used for in-situ enzyme soaking or direct discharge;

[0013] Preferably, the kitchen waste in step S1 is high-solid catering residues collected by the municipal government, excluding processing 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 2000-3000rpm, and TS≥20%.

[0014] Preferably, 10-20% by mass of sawdust and 1-10% by mass of bacterial agent are added to the solid residue in step S2, mixed evenly, and loaded into a 80-100 mesh columnar nylon bag. Under ventilation conditions of 0.5-1L / min air, the bag is mechanically stirred at 30-60rpm and wrapped with heat-insulating cotton on the outside 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 inoculum, and adds an equal amount of kitchen waste solid residue, 80% of sawdust and 50% of bacterial agent as the previous batch of experiments, and repeats the operation. Finally, the SCOD of each batch of experimental soaking liquid is 2400 mg / L, TN is 175 mg / L, and the overall VS removal rate of the solid residue is 21.5%.

[0017] Preferably, 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%, and 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, and the pore size of the bottom filter plate is ≤1mm. During this period, ventilation and mechanical stirring are closed, and after drip filtration, the in situ enzyme production is continued for 3 days to degrade the remaining organic matter to achieve the effect of reduction.

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

[0019] Preferably, in step S4, the mass ratio of solid residue to in-situ enzyme soaking liquid is 1: (2.5-5), tidal soaking is performed once every 6-12 hours, the pore size of the bottom filter plate is ≤1mm, the leachate completely submerges the pile and is 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 2.5-4L 空气 / kg 固渣 When the TCOD of the leachate is greater than 8000 mg / L, 25% of the leachate is discharged for UASB methanogenesis. On the last day, 75% of the leachate is discharged for UASB methanogenesis. The next batch of experiments uses 20% of the remaining substrate from the previous batch of experiments as inoculum, adds 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 mixes the remaining 25% of the leachate from the previous batch of experiments with the in situ enzyme soaking solution for tidal soaking operation, and repeats the operation. UASB is inoculated with anaerobic granular sludge, and the inoculation ratio is 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.

[0020] Preferably, the cycle of in situ enzyme production and anaerobic fermentation is 6 days. First, in situ enzyme production is carried out for 3 days to obtain a soaking liquid 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, and on the 6th day of anaerobic fermentation, the soaking liquid produced by the second batch of in situ enzyme production is used for tidal soaking operation, so as to realize the continuous repetition of the experimental cycles of the two.

[0021] (III) Beneficial effects

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

[0023] (1) The method for treating solid food waste residue by in-situ enzyme production and micro-aeration tidal percolation bed improves the initial hydrolysis efficiency of the tidal percolation bed by using the solid food waste residue to produce enzymes in-situ and extracting enzymes by soaking in tap water; micro-aeration promotes microbial activity and accelerates the process of anaerobic fermentation hydrolysis and acid production; the residual substrate of in-situ enzyme production and anaerobic fermentation is used for back-end treatment to further decompose organic matter, thereby realizing the coupled treatment of food waste residue reduction and resource utilization. This method uses the discarded solid food waste residue for resource utilization, realizes the transformation of waste into treasure, improves the resource utilization of food waste, applies the self-produced enzyme to the tidal percolation bed, accelerates the initial hydrolysis efficiency of the solid food waste residue, shortens the treatment time, and improves the treatment efficiency.

[0024] (2) The method for treating solid residues of kitchen waste by in-situ enzyme production and micro-aeration tidal percolation bed accelerates the hydrolysis efficiency of solid residues, shortens the treatment time, and improves the treatment efficiency by using micro-aeration in the tidal percolation bed; the in-situ enzyme production is coupled with anaerobic fermentation to rapidly produce enzymes under aerobic conditions, and part of the organic matter is provided to the anaerobic fermentation, thereby reducing the loss of organic matter in the in-situ enzyme production process and accelerating the anaerobic fermentation process. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0027] In the figure, 1. Wet heat treatment unit; 2. In-situ enzyme production reactor; 5. Micro-aerated tidal percolation bed; 6. UASB methane production. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] See also Figure 1-2 The present invention provides two technical solutions: a method for treating solid residues of kitchen waste by in-situ enzyme production and micro-aeration tidal percolation bed, which specifically includes the following embodiments:

[0030] Embodiment 1:

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

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

[0033] (2) In the in-situ enzyme production reactor 2, 150 g of solid food waste (TS = 22.59%, VS = 20.86%) was taken, 22.5 g of sawdust and 7.5 g of EM inoculant were added, and after being mixed evenly, an 80-mesh columnar nylon bag (volume 1 L) was added. The nylon bag was 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, the reactor was operated at 37 ° C for 3 days, and then aeration and stirring were stopped. After soaking in 0.75 L of tap water for 30 minutes, the drain was opened, and the residual water in the pile was drip filtered for 6 hours to obtain a soaking liquid rich in self-produced enzymes. After drip filtration, the fermentation was continued for 3 days to further degrade organic matter, achieving a rapid reduction effect. The next batch of experiments used 20% of the remaining substrate from the previous batch of experiments as inoculum, added 150 g of solid food waste, 18 g of sawdust and 3.75 g of inoculant, and repeated the operation. Finally, the SCOD of each batch of experimental soaking liquid was 2400 mg / L, TN was 175 mg / L, and the overall VS removal rate of solid slag was 21.5%.

[0034] (3) Take 200g of solid food waste (TS=22.59%, VS=20.86%) from the micro-aerated tidal filter bed 5, add 30g of sawdust and 3g of centrifugal anaerobic sludge preheated at 75℃ for 15min, mix well and add into an 80-mesh columnar nylon bag (volume 1L), and place the nylon bag on the 1mm filter plate of the reactor. Every 12h, use 1L of the soaking liquid produced on the 3rd day in step 2 (add 250mL of tap water to dilute) to perform a tidal soaking of the pile once, soak for 1-2h, and drain into the leachate storage tank. Before the second soaking, adjust the leachate pH to 6 in the leachate storage tank. If the leachate pH is between 6-8, do not adjust it. 4h after the first soaking, add 2.5L 空气 / kg 固渣 The leachate was exposed to air at a rate of 10 min to promote microbial growth. When the leachate TCOD>8000 mg / L, 25% of the leachate was discharged for methanogenesis, and 75% of the leachate was discharged on the 6th day for methanogenesis. The next batch of experiments used 20% of the remaining substrate from the previous batch of experiments as inoculum, added 200g of solid food waste, 24g of sawdust and 3g of centrifugal anaerobic sludge preheated at 75℃ for 15min, and the remaining 25% of the leachate was mixed with the soaking liquid in step 2 for tidal soaking operation, and the operation was repeated. Finally, on the 3rd and 5th day of each batch of experiments, the leachate TCOD>8000mg / L, and a total of 500mL of leachate was discharged; on the 6th day, 750mL of leachate was discharged, and the leachate TCOD=8098mg / L, SCOD=7963mg / L, ammonia nitrogen=428mg / L, and the overall hydrolysis yield of the kitchen waste solid residue reached 310g cum.SCOD / kg VS added , the overall acidification yield reached 230gcum.SCOD / kg VS added .

[0035] (4) The cycle of in situ enzyme production and tidal diafiltration fermentation (anaerobic fermentation) is 6 days. First, in situ enzyme production is carried out for 3 days to obtain a soaking liquid rich in self-produced enzymes, and then anaerobic fermentation is started. On the third day of anaerobic fermentation, in situ enzyme production enters the next batch of experiments; on the sixth day of anaerobic fermentation, the soaking liquid produced by the second batch of in situ enzyme production is used for tidal soaking operation, so that the experimental cycles of the two can be repeated continuously.

[0036] (5) In UASB methane production 6, the leachate (acidified liquid) produced in step 3 is measured in gCOD 酸化液 :gVS 颗粒污泥 = 1 inoculation, and add some tap water to adjust the initial SCOD concentration to 5000 mg / L. After running for 4 days, the cumulative methane yield of each batch of experimental acidified liquid reached 307.06 mL CH 4 / gTCOD 酸化液 , the cumulative gas production reached 19.2m3 / t 餐厨垃圾固渣 , and the SCOD removal rate is above 95%.

[0037] (6) The remaining substrates produced by in situ enzyme production and anaerobic fermentation are all processed at the back end.

[0038] Embodiment 2:

[0039] The method for treating solid residues of kitchen waste by in-situ enzyme production and micro-aeration tidal percolation bed uses organic solid residues separated from kitchen waste after wet heat treatment as raw materials, and treats them by coupling 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 kitchen waste is sorted, crushed and impurities removed, the slurry is heated in a high-pressure sterilization tank at 100°C for 60 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;

[0041] S2, in-situ enzyme production: solid residue, sawdust and bacterial agent are mixed and packed into 80-mesh cylindrical nylon bags, fermented at 25°C for 3 days, and internal mechanical stirring is used to achieve the effect of turning the pile to increase the activity of microorganisms;

[0042] 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. Continue 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;

[0043] S4, tidal percolation fermentation uses solid residue, sawdust and preheated inoculated sludge mixed and packed into 80 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 pH of the leachate is controlled 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; 20% of the remaining substrate serves as the inoculum for the next fermentation, and the remaining substrate is still processed at the back end. The leachate is used for UASB methane production, and the UASB effluent is used for in-situ enzyme soaking or direct discharge;

[0044] In the embodiment of the present invention, the kitchen waste in step S1 is high-solid catering residues collected by the municipal government, excluding processing residues from food processing plants, and the solid residue is the solid phase after wet heat treatment at 100° C. and three-phase separation and oil removal at 2000 rpm, and TS≥20%.

[0045] In an embodiment of the present invention, 10-20% by mass of sawdust and 1% by mass of bacterial agent are added to the solid residue in step S2, the mixture is evenly mixed, and the mixture is put into an 80-mesh cylindrical nylon bag. Under the ventilation condition of 0.5 L / min air, the bag is mechanically stirred at 30 rpm and the bag is wrapped with heat-insulating cotton on the outside to reduce heat loss. The bacterial agent includes but is not limited to EM bacterial agent, Bacillus subtilis, Aspergillus awamori, Aspergillus oryzae and Aspergillus niger.

[0046] In an embodiment of the present invention, after step S3, in situ enzyme production for 3 days, tap water is added from the top of the device to cover the volume of the in situ enzyme 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 size of the bottom filter plate is ≤1 mm. During this period, ventilation and mechanical stirring are closed. After drip filtration, the in situ enzyme production is continued for 3 days to continue to degrade organic matter, thereby achieving a reduction effect.

[0047] In the embodiment of the present invention, 10% by mass of sawdust and 10% by mass of inoculated sludge are added to the solid residue in step S4, the inoculated sludge is subjected to a 75°C water bath for 15 minutes, and after centrifugation at 3000r for 15 minutes, it is inoculated with the bottom sediment after centrifugation and loaded into an 80-mesh columnar nylon bag, the in-situ enzyme production soaking liquid mass ratio of the solid residue is 1:2.5, the solid residue is soaked once in a tidal manner for 6 hours, the pore size of the bottom filter plate is ≤1mm, the leachate completely submerges the pile body and is fully soaked for 1 hour before being discharged into the leachate storage tank, the pH is adjusted to 6, the temperature is controlled at 50°C, the air is aerated for 10 minutes every 12 hours, and the micro-aeration rate is 2.5L 空气 / kg 固渣 When the leachate TCOD>8000mg / L, 25% of the leachate was discharged for UASB methanogenesis. On the last day, 75% of the leachate was discharged for UASB methanogenesis. The remaining 25% of the leachate was mixed with the in-situ enzyme soaking solution and used for the next tidal soaking operation. The UASB was inoculated with anaerobic granular sludge at a ratio of gTCOD 酸化液 :gVS 颗粒污泥 =0.5, UASB effluent is returned to the in-situ enzyme production reactor for pile soaking or directly discharged to the sewage treatment plant.

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

[0049] In summary, the present invention uses the solid residue of kitchen waste to produce enzymes in situ to produce enzymes quickly, and extracts enzymes by soaking in tap water, thereby improving the initial hydrolysis efficiency of the tidal percolation bed; microbial activity is promoted by micro-aeration, and the process of anaerobic fermentation hydrolysis and acid production is accelerated; the residual substrate of in-situ enzyme production and anaerobic fermentation is used for back-end treatment to further decompose organic matter, thereby realizing the coupled treatment of food waste solid residue reduction and resource utilization. The discarded solid residue of kitchen waste is used for resource treatment, which realizes the transformation of waste into treasure and improves the resource utilization degree of kitchen waste. The self-produced enzyme is applied to the tidal percolation bed, which accelerates the initial hydrolysis efficiency of the solid residue of kitchen waste, shortens the processing time, and improves the processing efficiency. By using micro-aeration for the tidal percolation bed, the hydrolysis efficiency of the solid residue is accelerated, the processing time is shortened, and the processing efficiency is improved; the in-situ enzyme production and anaerobic fermentation are coupled, the enzyme is produced quickly under aerobic conditions, and part of the organic matter is provided to the anaerobic fermentation, which reduces the loss of organic matter in the in-situ enzyme production and accelerates the anaerobic fermentation process.

[0050] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

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

[0052] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that 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 the treatment is carried out by coupling the in-situ enzyme production and tidal percolation fermentation (anaerobic 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 uses solid residue, sawdust and preheated inoculated sludge 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 submerges 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 leachate pH 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; 20% of the remaining substrate serves as the inoculum for the next fermentation, and the remaining substrate is still processed in the back end. The leachate is used for UASB methanogenesis, and the UASB effluent is used for in situ enzyme production 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 2000-3000rpm.

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 0.5-1L / min air, the bag is mechanically stirred at 30-60rpm 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 kitchen waste solid 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 the 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 minutes and centrifuged at 3000-4000r for 15 minutes. 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), tidal soaking is performed once every 6-12 hours, the pore size of the bottom filter plate is ≤1mm, the leachate completely submerges the pile and is 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 2.5-4L 空气 / kg 固渣 When the TCOD of the leachate is greater than 8000 mg / L, 25% of the leachate is discharged for UASB methanogenesis. On the last day, 75% of the leachate is discharged for UASB methanogenesis. The next batch of experiments uses 20% of the remaining substrate from the previous batch of experiments as inoculum, adds 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 mixes the remaining 25% of the leachate from the previous batch of experiments with the in situ enzyme soaking solution for tidal soaking operation, and repeats the operation. UASB is inoculated with anaerobic granular sludge, and the inoculation ratio is 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 cycle of in situ enzyme production and anaerobic fermentation is 6 days. First, in situ enzyme production is carried out for 3 days to obtain a soaking liquid rich in self-produced enzymes, and then anaerobic fermentation is started. On the third day of anaerobic fermentation, the in situ enzyme production entered the next batch of experiments, and on the sixth day of anaerobic fermentation, the soaking liquid produced by the second batch of in situ enzyme production was used for tidal soaking operation to achieve continuous repetition of the two experimental cycles.

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