A self-heating aerobic digestion technology for high-concentration organic wastewater

Abstract

The present invention discloses a self-heating aerobic digestion technology for high-concentration organic waste liquid, which belongs to the technical field of high-concentration organic waste liquid treatment and resource utilization. The present invention utilizes extreme thermophilic bacteria to compound targeted functional bacterial agents, mixes high-concentration organic waste liquid (SS is about 100g / L-150g / L) with targeted functional bacterial agents, and maintains a digestion temperature of more than 80°C for at least 5 days through heat assistance + spontaneous heating during the reproduction and metabolism of extreme thermophilic bacteria. The digestion products can be rendered harmless, reduced in quantity and recycled in 7-10 days, and carbon emissions in the treatment process can be reduced by 15-30%. The present invention subverts the technical bottleneck of traditional extreme thermophilic bacteria for aerobic fermentation of organic waste, saves energy, and realizes high-speed stabilization of high-concentration organic waste liquid.

Description

Technical Field

[0001] The invention belongs to the technical field of high-concentration organic waste liquid treatment and resource utilization, and specifically relates to a self-heating aerobic digestion technology for high-concentration organic waste liquid. Background Art

[0002] According to national environmental regulations, wastewater must be treated to reduce its COD to below 300 mg / L before being discharged to land. For discharge into waterways, the COD level should be below 80 mg / L. Limited by low technological standards, environmental protection investments and equipment operating costs were prohibitive for businesses. Because environmental compliance was often a "soft target" in implementation, few companies truly treated wastewater to meet standards. Discharge into rivers, streams, and lakes was common, leading to frequent pollution accidents. Some companies, at best, leased farmland near their factories for long periods of time and stored the wastewater in small reservoirs or ponds, allowing it to be diluted by rainwater and naturally oxidized, gradually reducing its COD level over two to three years. However, this still resulted in organic pollutants seeping into the ground and ultimately into waterways. Furthermore, the resulting air pollution (and odor) was also significant.

[0003] How to select appropriate treatment technologies for high-concentration organic wastewater and combine them into a cost-effective solution is a matter of great concern. The best technical approach for treating high-concentration organic wastewater, recognized both domestically and internationally, is a two-step process. First, anaerobic fermentation is used to rapidly reduce the COD value in the wastewater over a short period of time (20-30 hours). This is because anaerobic fermentation consumes less energy and is inexpensive. Once the COD value has dropped to a certain level, aerobic fermentation is then used to treat the wastewater, reducing it to below the environmental discharge permit standard. A comprehensive treatment technology approach should take into account the characteristics of high-concentration organic wastewater (high COD, high BOD, and high bacterial count), while also being economically feasible and meeting resource requirements. Generally speaking, the treatment of high-concentration organic wastewater generally requires pretreatment and post-treatment, or a combination of anaerobic and aerobic secondary treatment. Biotechnology is more mature, but it requires significant equipment investment, large footprint, and high operating and maintenance costs. If the COD value of the water remains high after anaerobic treatment, additional aerobic or physicochemical treatment may be necessary. In short, it is difficult to completely treat high-concentration organic wastewater using one method, and a two-stage or three-stage treatment method is required to meet the standards.

[0004] Generally, when the temperature exceeds 50°C, without any interference, the dissolved oxygen in hot water will drop sharply to below 10 mg / L, which will inhibit the growth of thermophiles. Therefore, thermophiles are generally used for solid aerobic fermentation, such as livestock and poultry manure, dead leaves, straw, etc. Extreme thermophiles are generally found in craters, hot springs, etc. Due to their unique growth environment, they can theoretically grow in hot water >80°C. Therefore, if the growth conditions and reproduction requirements of extreme thermophiles can be guaranteed, then self-heating aerobic digestion can be achieved in high-concentration organic waste liquids. However, there is a lack of technical solutions for how to keep extreme thermophiles alive in a liquid environment and enable them to complete the treatment of high-concentration organic waste liquids. Summary of the Invention

[0005] The present invention aims to address the urgent need for treating high-concentration organic wastewater with high COD, BOD, and / or SS concentrations by providing a self-heating aerobic digestion technology. This method offers high feasibility, ease of operation, and flexibility (including a wide variety of microorganisms). It also reduces carbon emissions, achieving a win-win situation for both environmental and economic benefits.

[0006] In order to achieve the above object, the present invention provides a method for autothermal aerobic digestion of high-concentration organic wastewater, comprising the following steps:

[0007] (1) Activation of extreme thermophilic microorganisms and compounding with targeted functional microbial agents: amplifying and culturing extreme thermophilic bacteria, adding rhamnolipids and sophorolipids during amplification, and then compounding multiple extreme thermophilic bacteria into a microbial agent; or, compounding multiple extreme thermophilic bacteria into a microbial agent and then amplifying and culturing, adding rhamnolipids and sophorolipids during amplification; wherein the microbial agent includes but is not limited to extreme thermophiles that can degrade proteins, extreme thermophiles that can degrade polysaccharides, and / or extreme thermophiles that can degrade cellulose;

[0008] (2) Pre-solubilization and emulsification of high-concentration organic waste liquid: Add lipopeptides and lipoproteins to high-concentration organic waste liquid with SS of 100g / L-150g / L to increase the solubility of the high-concentration organic waste liquid and accelerate emulsification;

[0009] (3) Digestion and volume reduction of high-concentration organic waste liquid: The microbial agent of step (1) and the high-concentration organic waste liquid pretreated in step (2) are mixed, and a certain amount of mannoprotein is added. The mixture is stirred and aerated at a temperature of 50-55°C and a dissolved oxygen of 6-15 mg / L. The digestion treatment is carried out for 7-10 days to complete the digestion of the high-concentration organic waste liquid.

[0010] The autothermal aerobic digestion technology described in the present invention has a treatment time of 7-10 days. After filter pressing and dehydration, the wastewater can meet the standard of "GB 20922-2007 Urban Wastewater Recycling and Agricultural Irrigation Water Quality". The final solid product meets the harmlessness standard (seed germination index >80%, pathogenic microorganism killing 100%) and stabilization (degradation rate of organic matter such as protein, fat, polysaccharide, and cellulose is 45-80%, and the final total organic matter content is 45-60%).

[0011] Preferably, in step (1), the targeted functional bacterial agent preferably includes extreme thermophiles that can degrade proteins, extreme thermophiles that can degrade polysaccharides, and extreme thermophiles that can degrade cellulose.

[0012] Preferably, in the targeted functional bacterial agent, the extreme thermophilic bacteria that can degrade proteins account for 40-50%; the extreme thermophilic bacteria that can degrade polysaccharides account for 30-40%; and the extreme thermophilic bacteria that can degrade cellulose account for 10-30%.

[0013] Preferably, in step (1), the extreme thermophilic bacteria capable of degrading protein is at least one of Geobacillus stearothermophilus and Parageobacillus toebii; the extreme thermophilic bacteria capable of degrading polysaccharides is at least one of Thermus tengchongensis and Thermus amyloliquefaciens; and the extreme thermophilic bacteria capable of degrading cellulose is at least one of Geobacillus sp. WCH70 and Geobacillus sp. CX412.

[0014] Preferably, the concentration of the microbial agent in step (1) is 1.3-1.5×10 9 CFU / g and above.

[0015] Preferably, the rhamnolipid and sophorolipid added in step (1) are mixed in a ratio of 2-6:1-3 (m / m, mass ratio), and the added content is 0.2-0.8 mg / L, in order to activate and enhance the degradation ability of extreme thermophilic bacteria.

[0016] Preferably, in step (1), the culture medium for amplifying and culturing extreme thermophiles is 8-12 g of tryptone, 5-7 g of casein, 3-5 g of glucose, 3-5 g of sodium chloride, 1.5-2 g of disodium hydrogen phosphate, 10-12 g of dehydrated calf brain extract powder, 10-15 g of agar, and a pH value of 7.0-7.4.

[0017] Preferably, the lipopeptide and lipoprotein added in step (2) have a compounding ratio of 1-5:2-3 (m / m, mass ratio), and the added content is 1.2-2.5 mg / L.

[0018] Preferably, the mixing ratio of the microbial agent to the organic waste liquid in step (3) is 0.1-0.3:1 (v / v).

[0019] Preferably, the mannoprotein added in step (3) has an added content of 0.8-3.2 mg / L.

[0020] Preferably, the stirring in step (3) is low-speed stirring, and preferably, the low-speed stirring rate is 0.05-0.25 Hz / L.

[0021] Preferably, a defoaming agent is further added in step (3), and the defoaming agent is a silicone defoaming agent with an addition ratio of 0.1-0.5 mg / L.

[0022] Preferably, the aeration in step (3) is preferably aeration using a nano-micro bubble device.

[0023] Preferably, this patent is applicable to high-concentration organic waste liquid with SS of 100g / L-150g / L, which mainly comes from food waste, livestock and poultry manure, sludge, etc.

[0024] Preferably, the digestion treatment in step (3) can be performed by filter pressing and dehydration before discharge.

[0025] Preferably, the method of the present invention comprises the following steps:

[0026] (1) Activation of extreme thermophilic microorganisms and compounding of microbial agents

[0027] Select a variety of heterotrophic microorganisms that can promote each other's growth and reproduction at 75-85℃. When amplifying and reproducing microorganisms, add a small amount of rhamnolipids and sophorolipids to activate and enhance the degradation ability of extreme thermophilic microorganisms.

[0028] Extreme thermophilic bacteria that can degrade different organic matter (rich in protein, polysaccharides, etc.) are compounded into targeted functional bacteria agents. Among them, functional bacteria that can degrade protein account for 40-50%; functional bacteria that can degrade polysaccharides account for 30-40%; functional bacteria that can degrade cellulose account for 10-30%;

[0029] (2) Pre-solubilization and emulsification of high-concentration organic wastewater

[0030] Add lipopeptides and lipoproteins to high-concentration organic waste liquid with SS of 100g / L-150g / L to increase the solubility of the high-concentration organic waste liquid and accelerate emulsification;

[0031] (3) Digestion and volume reduction of high-concentration organic wastewater

[0032] The targeted functional bacterial agent prepared in step 1) is mixed with the high-concentration organic wastewater pretreated in step 2), and a certain amount of mannoprotein is added to promote autothermal aerobic digestion to regulate the affinity between the microorganisms and the organic matter. Using low-speed stirring and aeration with a nano-microbubble device, an ambient temperature of 50-55°C, and a dissolved oxygen level of 6-15 mg / L, the aerobic digestion temperature can exceed 80°C and be maintained at this temperature for at least 5 days, completing the digestion of the high-concentration organic wastewater.

[0033] Compared with the existing technology, the present invention has the following advantages:

[0034] (1) The method of the present invention can effectively achieve the harmlessness and reduction of high-concentration organic waste liquid (up to more than 90%), and reduce carbon emissions during the treatment process. The carbon emissions of general aerobic technology can reach 30-80 kg / t, while the carbon emissions of the present invention can be reduced by 15-30%.

[0035] (2) Aerobic digestion generally uses common thermophiles such as actinomycetes and thermotolerant Bacillus. Currently, extreme thermophiles are only used for solid-state fermentation. The present invention uses extreme thermophiles to achieve ultra-high temperature aerobic digestion of high-concentration organic wastewater, and clarifies the specific operation and effect judgment methods. The aerobic digestion time is shortened from the traditional 30-60 days to 7-10 days, and the process temperature is increased by 20-30°C. One of the innovations of the present invention is to enable extreme thermophiles to survive in a liquid environment and enable them to complete the treatment of high-concentration organic wastewater. DETAILED DESCRIPTION

[0036] The following is further described in detail with reference to examples. It should be understood that the following examples are only for illustrating the present invention and do not include all the contents of the present invention.

[0037] The culture medium for amplifying and culturing extremely thermophilic microorganisms in the embodiment of the present invention includes: 10g of tryptone, 6g of casein, 4g of glucose, 4g of sodium chloride, 1.75g ​​of disodium hydrogen phosphate, 11g of dehydrated calf brain extract powder, 13g of agar, and a pH value of 7.0-7.4.

[0038] Example 1

[0039] For high-concentration organic wastewater (SS at 120g / L, sourced from the suspended supernatant after sludge mixing), the autothermal aerobic digestion technology using a microbial agent compounded with extreme thermophilic bacteria is used, including the following steps:

[0040] 1) Activation of extreme thermophilic microorganisms and compounding of microbial agents

[0041] Heterotrophic microorganisms that can grow and reproduce at 75-85°C are selected to ensure that they do not inhibit each other's growth. Then, extreme thermophiles that degrade different organic matter (rich in protein, polysaccharides, etc.) are compounded into microbial agents. 0.6 mg / L of rhamnolipids and sophorolipids are added during amplification culture, with a compounding mass ratio of 2:3, to activate and enhance the degradation ability of extreme thermophilic microorganisms. Among them, the ratio of extreme thermophiles that degrade protein: extreme thermophiles that degrade polysaccharides: extreme thermophiles that degrade cellulose is 50:40:10. The final bacterial concentration of the compounded agent is 1.35×10 9 CFU / g.

[0042] The extreme thermophilic bacteria that degrade protein is Geobacillus stearothermophilus; the extreme thermophilic bacteria that degrade polysaccharides is Thermus amyloliquefaciens; and the extreme thermophilic bacteria that degrade cellulose is Geobacillus sp. WCH70.

[0043] 2) Pre-solubilization and emulsification of high-concentration organic wastewater

[0044] 1.8 mg / L lipopeptide and lipoprotein (compound mass ratio of 2:3) were added to high-concentration organic waste liquid with SS of 120 g / L (derived from sludge mixed suspension) to increase the solubility of the high-concentration organic waste liquid while accelerating emulsification.

[0045] 3) Treatment of organic waste

[0046] The targeted functional bacterial agent prepared in step 1) and the pretreated SS from step 2) were mixed with 120 g / L high-concentration organic wastewater (derived from a sludge suspension) at a ratio of 0.15:1 (v / v). 2.8 mg / L of mannoprotein was added to promote autothermal aerobic digestion and regulate the affinity between the microorganisms and the organic matter. The ambient temperature was maintained at 50.8°C, and aeration was performed using a nano-microbubble device with 75% pure oxygen and a bubble diameter of <50 μm. Low-speed stirring was used at a stirring rate of 0.15 Hz / L, and a certain amount of defoamer was added to eliminate bubbles generated during fermentation. The defoamer was BD-303, a silicone defoamer, at a concentration of 0.3 mg / L. The dissolved oxygen content in the liquid was maintained at 10 mg / L. The treatment lasted for 7 days, with a temperature of 80-82°C maintained for 6 days. The fermentation was then dehydrated by filtration.

[0047] Testing revealed that the resulting wastewater met the standards for "GB 20922-2007 Water Quality for Agricultural Irrigation Use of Urban Wastewater Reuse," and the final solid product achieved harmlessness standards (seed germination index >80%, pathogenic microorganism kill 100%) and stabilization (degradation rate of protein, fat, polysaccharide, and cellulose organic matter was 53%, with a final total organic matter content of 52%). The water content was reduced to 50%. This demonstrates that the present invention can achieve high-speed stabilization of high-concentration organic wastewater using extreme thermophiles while saving energy.

[0048] Example 2

[0049] For high-concentration organic waste liquid (SS at 150g / L, sourced from a 1:1 mixed suspension of equal volumes of kitchen waste and sludge), the autothermal aerobic digestion technology using a microbial agent compounded with extreme thermophilic bacteria is used.

[0050] 1. The autothermal aerobic digestion technology for high-concentration organic wastewater includes the following steps:

[0051] 1) Activation of extreme thermophilic microorganisms and compounding of microbial agents

[0052] Heterotrophic microorganisms that can grow and reproduce at 75-85°C are selected to ensure that they do not inhibit each other's growth. Then, extreme thermophiles that degrade different organic matter (rich in protein, polysaccharides, etc.) are compounded into microbial agents. 0.5 mg / L of rhamnolipids and sophorolipids are added during amplification culture, with a compounding mass ratio of 2:3, to activate and enhance the degradation ability of extreme thermophilic microorganisms. Among them, the ratio of extreme thermophiles that degrade protein: extreme thermophiles that degrade polysaccharides: extreme thermophiles that degrade cellulose is 40:30:30. The final bacterial concentration of the compounded agent is 1.48×10 9 CFU / g.

[0053] The extreme thermophilic bacteria that degrade protein is Parageobacillus toebii; the extreme thermophilic bacteria that degrade polysaccharides is Thermus amyloliquefaciens; and the extreme thermophilic bacteria that degrade cellulose is Geobacillus sp. CX412.

[0054] 2) Pre-solubilization and emulsification of high-concentration organic wastewater

[0055] 2.1 mg / L lipopeptides and lipoproteins (with a combined mass ratio of 5:3) were added to a high-concentration organic waste liquid with an SS of 150 g / L (derived from a 1:1 volume mixed suspension of kitchen waste and sludge), thereby increasing the solubility of the high-concentration organic waste liquid and accelerating emulsification.

[0056] 3) Treatment of organic waste

[0057] The compounded microbial inoculant from step 1) was mixed with high-concentration organic wastewater (derived from 150g / L SS food waste and sludge in a 1:1 ratio) at a mixing ratio of 0.2:1 (v / v). 1.8mg / L of mannoprotein was added to promote autothermal aerobic digestion and regulate the affinity between the microorganisms and the organic matter. The ambient temperature was 52.1°C, and a nano-microbubble device was used for aeration, using 85% pure oxygen with a bubble diameter of <50μm. Low-speed stirring was used at a stirring rate of 0.25Hz / L, and a defoamer was used to eliminate bubbles generated during fermentation. The defoamer was a silicone-based defoamer, polydimethylsiloxane, at a concentration of 0.25mg / L to maintain a dissolved oxygen content of 12mg / L. The treatment lasted 10 days, with a temperature of 82-85°C maintained for 7.5 days. The product was then dehydrated by filtration.

[0058] After testing, it was found that the wastewater can meet the standard of "GB 20922-2007 Water Quality for Agricultural Irrigation of Urban Wastewater Recycling"; the final solid product can meet the harmlessness standard (seed germination index>80%, pathogenic microorganism killing 100%) and stabilization (the degradation rate of protein, fat, polysaccharide, and cellulose organic matter is 77%, and the final total organic matter content is 48%), and the moisture content can be reduced to 52.3%.

[0059] This shows that the present invention can achieve high-speed stabilization of high-concentration organic waste liquid by utilizing extreme thermophilic bacteria while saving energy.

[0060] Comparative Example 1

[0061] Compared with Example 1, the difference is that instead of using a compound microbial agent, a common aerobic digestion agent is used, with Bacillus licheniformis: Bacillus urealyticum: Methanothermus = 50:40:10, and the final bacterial concentration is 1.35×10 9 CFU / g. 0.6 mg / L of rhamnolipids and sophorolipids were added during the expansion culture, with a compound mass ratio of 2:3, to activate and enhance the degradation ability of aerobic digestion bacteria.

[0062] 1.8 mg / L lipopeptide and lipoprotein (compound mass ratio of 2:3) were added to high-concentration organic waste liquid with SS of 120 g / L (derived from sludge mixed suspension) to increase the solubility of the high-concentration organic waste liquid while accelerating emulsification.

[0063] Conventional aerobic digestion agents were mixed with treated high-concentration organic wastewater (derived from a sludge suspension with an SS content of 120 g / L) at a ratio of 0.15:1 (v / v). 2.8 mg / L of mannoprotein was added to promote autothermal aerobic digestion and regulate the affinity between the microorganisms and the organic matter. Aeration was performed using a nano-microbubble device at an ambient temperature of 50.8°C, using 75% pure oxygen and bubbles <50 μm in diameter. Low-speed stirring was used at a stirring rate of 0.15 Hz / L, along with a defoamer (BD-303, a silicone defoamer) at a concentration of 0.3 mg / L. Dissolved oxygen in the liquid was maintained at 10 mg / L. The temperature of the treatment process can only reach 52-55℃. On the 7th day, the seed germination index is 65%, the pathogenic microorganisms are killed by 75%, the degradation rate of protein, fat, polysaccharide and cellulose organic matter is 25%, and the final total organic matter content is 64%, which does not meet the requirements of harmlessness and stabilization.

[0064] After filter pressing and dehydration, the wastewater did not meet the standard of "GB 20922-2007 Water Quality for Agricultural Irrigation of Urban Wastewater Recycling". At the same time, the moisture content of the solid product after filter pressing and dehydration could only be reduced to 82%.

[0065] It is proved that high-speed stabilization of high-concentration organic waste liquid cannot be achieved without using the bacterial agent specified in the present invention.

[0066] Comparative Example 2

[0067] Compared with Example 1, the difference is that the high-concentration organic waste liquid is not pre-solubilized and emulsified.

[0068] The extreme thermophile that degrades proteins is Geobacillus stearothermophilus; the extreme thermophile that degrades polysaccharides is Thermus amyloliquefaciens; and the extreme thermophile that degrades cellulose is Geobacillus sp. WCH70. During the amplification culture, 0.6 mg / L of rhamnolipids and sophorolipids were added at a combined mass ratio of 2:3 to activate and enhance the degradation capacity of the extreme thermophilic microorganisms. The ratio of protein-degrading extreme thermophiles: polysaccharide-degrading extreme thermophiles: cellulose-degrading extreme thermophiles was 50:40:10. The final bacterial concentration of the combined bacterial agent was 1.35×10 9 CFU / g.

[0069] A composite functional bacterial agent was mixed with a high-concentration organic wastewater (derived from a sludge suspension with an SS content of 120 g / L) at a ratio of 0.15:1 (v / v). 2.8 mg / L of mannoprotein was added to promote autothermal aerobic digestion to regulate the affinity between the microorganisms and the organic matter. Aeration was performed using a nano-microbubble device at an ambient temperature of 50.8°C, using 75% pure oxygen and a bubble diameter of <50 μm. Low-speed stirring was used at a stirring rate of 0.15 Hz / L, along with a defoamer containing 0.3 mg / L of BD-303, a silicone defoamer, to eliminate bubbles generated during fermentation. The dissolved oxygen content in the liquid was maintained at 10 mg / L. The treatment process temperature could only reach a maximum of 70-72°C. On the seventh day, the seed germination index was 75%, pathogenic microorganisms were killed by 95%, and the degradation rate of protein, fat, polysaccharide, and cellulose organic matter was 30%. The final total organic matter content was 62%, failing to meet the requirements for harmlessness and stabilization. After filter pressing and dehydration, the wastewater did not meet the standard of "GB 20922-2007 Municipal Wastewater Reuse and Agricultural Irrigation Water Quality". Furthermore, the moisture content of the solid product after filter pressing and dehydration could only be reduced to 75%.

[0070] It is proved that when high-concentration organic waste liquid is not pre-solubilized and emulsified, the microbial agent compounded with extreme thermophilic bacteria cannot achieve high-speed stabilization of high-concentration organic waste liquid.

[0071] Comparative Example 3

[0072] Compared with Example 1, the difference is that the compounded rhamnolipid and sophorolipid are not added in step 1 and the compounded lipopeptide and lipoprotein are not added in step 2, but single rhamnolipid and lipoprotein are used respectively.

[0073] The extreme thermophile that degrades proteins is Geobacillus stearothermophilus; the extreme thermophile that degrades polysaccharides is Thermus amyloliquefaciens; and the extreme thermophile that degrades cellulose is Geobacillus sp. WCH70. 0.6 mg / L of rhamnolipid was added during the expansion culture to activate and enhance the degradation capabilities of the extreme thermophiles. The ratio of the extreme thermophile that degrades proteins: the extreme thermophile that degrades polysaccharides: the extreme thermophile that degrades cellulose was 50:40:10. The final bacterial concentration of the combined inoculum was 1.35×10 9 CFU / g.

[0074] 1.8 mg / L lipoprotein was added to high-concentration organic waste liquid (source: sludge mixed suspension) with SS of 120 g / L to increase the solubility of the high-concentration organic waste liquid and accelerate emulsification.

[0075] A composite functional bacterial agent was mixed with a high-concentration organic wastewater (derived from a sludge suspension with an SS content of 120 g / L) at a ratio of 0.15:1 (v / v). 2.8 mg / L of mannoprotein was added to promote autothermal aerobic digestion to regulate the affinity between the microorganisms and the organic matter. Aeration was performed using a nano-microbubble device at an ambient temperature of 50.8°C, using 75% pure oxygen and a bubble diameter of <50 μm. Low-speed stirring was used at a stirring rate of 0.15 Hz / L, along with a defoamer containing 0.3 mg / L of BD-303, a silicone defoamer, to eliminate bubbles generated during fermentation. The dissolved oxygen content in the liquid was maintained at 10 mg / L. The treatment process reached a maximum temperature of 80-82°C for only two days. On the seventh day, the seed germination index was 76%, pathogenic microorganisms were killed by 98%, and the degradation rate of protein, fat, polysaccharide, and cellulose organic matter was 35%. The final total organic matter content was 60%, failing to meet the requirements for harmlessness and stabilization. After filter pressing and dehydration, the wastewater did not meet the standard of "GB 20922-2007 Municipal Wastewater Reuse and Agricultural Irrigation Water Quality". Furthermore, the moisture content of the solid product after filter pressing and dehydration could only be reduced to 68%.

[0076] It is proved that high-speed stabilization of high-concentration organic waste liquid cannot be achieved when the compound reagent specified in the present invention is not used.

[0077] Comparative Example 4

[0078] Compared with Example 1, the difference is that no mannoprotein is added to promote the autothermal aerobic digestion technology to regulate the affinity between microorganisms and organic matter.

[0079] The extreme thermophile that degrades proteins is Geobacillus stearothermophilus; the extreme thermophile that degrades polysaccharides is Thermus amyloliquefaciens; and the extreme thermophile that degrades cellulose is Geobacillus sp. WCH70. During the amplification culture, 0.6 mg / L of rhamnolipids and sophorolipids were added at a combined mass ratio of 2:3 to activate and enhance the degradation capacity of the extreme thermophilic microorganisms. The ratio of protein-degrading extreme thermophiles: polysaccharide-degrading extreme thermophiles: cellulose-degrading extreme thermophiles was 50:40:10. The final bacterial concentration of the combined bacterial agent was 1.35×10 9 CFU / g.

[0080] 1.8 mg / L lipopeptide and lipoprotein (compound mass ratio of 2:3) were added to high-concentration organic waste liquid with SS of 120 g / L (derived from sludge mixed suspension) to increase the solubility of the high-concentration organic waste liquid while accelerating emulsification.

[0081] A composite functional bacterial agent was mixed with a high-concentration organic wastewater (derived from a sludge suspension with a SS content of 120 g / L) at a ratio of 0.15:1 (v / v). A nano-microbubble device was used for aeration at an ambient temperature of 50.8°C, using 75% pure oxygen and bubbles <50 μm in diameter. Low-speed stirring was used at a stirring rate of 0.15 Hz / L, along with a defoamer to eliminate bubbles generated during fermentation. The defoamer, BD-303, a silicone defoamer, was added at a concentration of 0.3 mg / L. The dissolved oxygen content in the liquid was maintained at 10 mg / L. The treatment temperature reached a maximum of 80-82°C for only three days. On the seventh day, the seed germination index was 78%, pathogenic microorganisms were eliminated by 97%, and the degradation rates of proteins, fats, polysaccharides, and cellulose were 40%. The final total organic matter content was 56%, failing to meet the requirements for detoxification and stabilization. After filter pressing and dehydration, the wastewater did not meet the standard of "GB 20922-2007 Water Quality for Agricultural Irrigation of Urban Wastewater Recycling". At the same time, the moisture content of the solid product after filter pressing and dehydration could only be reduced to 67%.

[0082] It was demonstrated that high-speed stabilization of high-concentration organic wastewater could not be achieved without the addition of mannoprotein.

[0083] Table 1 Comparison of experimental results of Examples 1 to 2 and Comparative Examples 1 to 4

[0084]

[0085]

[0086] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for autothermal aerobic digestion of high-concentration organic wastewater, characterized in that: The following steps are involved: (1) Activation of extreme thermophilic microorganisms and compounding with targeted functional agents: amplifying and culturing extreme thermophilic bacteria, adding rhamnolipids and sophorolipids during amplification, and then compounding multiple extreme thermophilic bacteria into a microbial agent; or, compounding multiple extreme thermophilic bacteria into a microbial agent and then amplifying and culturing, adding rhamnolipids and sophorolipids during amplification; wherein the microbial agent includes but is not limited to extreme thermophiles that can degrade proteins, extreme thermophiles that can degrade polysaccharides, and / or extreme thermophiles that can degrade cellulose; (2) Pre-solubilization and emulsification of high-concentration organic waste liquid: Add lipopeptides and lipoproteins to high-concentration organic waste liquid with SS of 100g / L-150g / L to increase the solubility of the high-concentration organic waste liquid and accelerate emulsification; (3) Digestion and volume reduction of high-concentration organic waste liquid: The microbial agent of step (1) and the high-concentration organic waste liquid pretreated in step (2) are mixed, and a certain amount of mannoprotein is added. The mixture is stirred and aerated. The temperature is 50-55°C, the dissolved oxygen is 6-15 mg / L, and the digestion treatment is carried out for 7-10 days to complete the digestion of the high-concentration organic waste liquid.

2. The method for autothermal aerobic digestion of high-concentration organic wastewater according to claim 1, characterized in that: In step (1), the targeted functional bacterial agent preferably includes extreme thermophiles that can degrade proteins, extreme thermophiles that can degrade polysaccharides, and extreme thermophiles that can degrade cellulose.

3. The method for autothermal aerobic digestion of high-concentration organic wastewater according to claim 2, characterized in that: In the targeted functional bacterial agent, the extreme thermophilic bacteria that can degrade proteins account for 40-50%; the extreme thermophilic bacteria that can degrade polysaccharides account for 30-40%; and the extreme thermophilic bacteria that can degrade cellulose account for 10-30%.

4. The method for autothermal aerobic digestion of high-concentration organic wastewater according to claim 2, characterized in that: In step (1), the extreme thermophilic bacteria capable of degrading protein is Geobacillus stearothermophilus, Parageobacillus toebii At least one of the extreme thermophilic bacteria that can degrade polysaccharides is Thermus tengchongensis, Thermus amyloliquefaciens At least one of the extreme thermophilic bacteria that can degrade cellulose is Geobacillus sp. WCH70 、Geobacillus sp. At least one of the CX412.

5. The method for autothermal aerobic digestion of high-concentration organic wastewater according to claim 1, characterized in that: The concentration of the microbial agent in step (1) is 1.3-1.5×10 9 CFU / g and above.

6. The method for autothermal aerobic digestion of high-concentration organic wastewater according to claim 1, characterized in that: The rhamnolipid and sophorolipid added in step (1) are mixed in a ratio of 2-6:1-3 by mass, and the added content is 0.2-0.8 mg / L.

7. The method for autothermal aerobic digestion of high-concentration organic wastewater according to claim 1, characterized in that: The lipopeptide and lipoprotein added in step (2) are mixed in a ratio of 1-5:2-3 by mass, and the added content is 1.2-2.5 mg / L.

8. The method for autothermal aerobic digestion of high-concentration organic wastewater according to claim 1, characterized in that: The mixing volume ratio of the microbial agent to the organic waste liquid in step (3) is 0.1-0.3:

1.

9. The method for autothermal aerobic digestion of high-concentration organic wastewater according to claim 1, characterized in that: The mannoprotein added in step (3) has an added content of 0.8-3.2 mg / L.

10. The method for autothermal aerobic digestion of high-concentration organic wastewater according to claim 1, characterized in that: In step (3), a defoaming agent is also required to be added. The defoaming agent is a silicone defoaming agent, and the addition ratio is 0.1-0.5 mg / L.

11. The method for autothermal aerobic digestion of high-concentration organic wastewater according to any one of claims 1 to 9, characterized in that: After the digestion treatment in step (3), the product is discharged after being dehydrated by filtration.

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