Method for treating sewage by using microbial straw felt

Abstract

The invention discloses a method for treating sewage by using microbial straw felt, belonging to the technical field of sewage treatment.The method comprises the following steps: taking plant rhizome as a carrier, particularly taking wheat and rice straw as a microbial carrier; the method comprises the following steps: co-culturing with beneficial microorganisms capable of absorbing and converting pollutants such as nitrogen, phosphorus and macromolecular organic matters into microbial thalli and secondary metabolites, and forming a water body pollution factor capable of adsorbing and flocculating under the assistance of gel capable of solidifying and growing the microbial thalli on a carrier; the pollution factors are converted into nutrition of beneficial microbial flora, and finally become nutrition of aquatic animals and plants in manners of microbial films, algal-bacterial complexes and the like through growth and reproduction of the microbial flora, and enter a biodiversity chain, so that the water pollution factors are converted and removed from the water, and the aim of purifying the water is fulfilled at the same time. The method is suitable for various scenes, and has the advantages of efficient purification, eco-friendliness and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and more specifically, to a method for treating sewage by utilizing microbial grass mat. Background Art

[0002] As water pollution becomes more serious, ecological restoration technology with microorganisms as the core has become an important direction in the field of sewage treatment. The performance of microbial fillers directly determines the attachment efficiency of microbial communities, the ability to transform pollutants, and the long-term operation stability of the system. At present, the mainstream microbial fillers are mainly divided into the following three categories, but all of them have significant defects: 1. Organic materials; including natural organic materials and synthetic organic materials.

[0003] Natural organic materials include: wood (pine, oak, etc.), bamboo, and agricultural waste (such as corn cobs, rice husks, bagasse, etc.); although they are degradable, they have loose fiber structures, weak adhesion, and are easily decomposed to produce humic acid.

[0004] Synthetic organic materials include polyethylene (PE), polypropylene (PP), polystyrene (PS), etc. Although synthetic organic materials have high mechanical strength, their surface is highly hydrophobic and their biocompatibility is poor, which makes it difficult for microorganisms to attach, and the detached microbial colonies easily clog the gaps.

[0005] 2. Inorganic materials: including stones, gravel, ceramics, diatomaceous earth, activated carbon, etc., which have large specific surface area but low porosity. After long-term operation, they are prone to internal hypoxia due to bacterial accumulation, causing anaerobic decay.

[0006] 3. Composite materials; including organic-inorganic composite materials and composites of multiple organic materials, which combine the advantages and disadvantages of organic and inorganic materials.

[0007] The functional requirements of microbial fillers are: large specific surface area, strong adhesion, suitable for the growth of microbial communities, detached microbial clusters will not block the gaps, and agglomerated microbial communities will not affect the continued growth of functional microorganisms.

[0008] However, in actual application, the commonly used microbial fillers often cause filler blockage, lack of oxygen and rot of bacteria in the filler pile, etc., which requires stopping operation, draining sewage, and replacing fillers before restarting operation. Not only is the replacement cost very high, the maintenance cycle is long, and it will cause secondary pollution. Summary of the invention

[0009] The purpose of the present invention is to provide a method for treating sewage using microbial straw mat, so as to solve the technical problem that commonly used microbial fillers often cause filler blockage, filler pile bacteria lack of oxygen and rot, etc., and it is necessary to stop operation, empty sewage, and replace fillers before restarting operation. Not only is the replacement cost very high, the maintenance cycle is long, but it also causes secondary pollution.

[0010] In order to achieve these objectives of the present invention, the present invention provides a method for treating sewage using microbial straw mats, which is to weave plant rhizomes, especially rice or wheat straw with a hollow structure, into straw mats, and then co-cultivate them with beneficial microorganisms that can absorb and transform pollutants such as nitrogen, phosphorus and macromolecular organic matter into microbial cells and secondary metabolites. With the assistance of a gelling agent that can solidify and grow the microbial cells onto a carrier, a method is formed that can adsorb and flocculate water pollution factors and convert these pollution factors into nutrients for beneficial microbial flora. Through the growth and reproduction of the microbial community, it eventually becomes nutrition for aquatic plants and animals in the form of microbial biofilms, bacterial-algal complexes, etc., and enters the biodiversity chain, thereby transforming and removing water pollution factors from the water body, and achieving the purpose of purifying water quality at the same time.

[0011] This ecological treatment method is to convert soluble and insoluble pollutants in water bodies such as ammonia nitrogen, nitrate nitrogen, total phosphorus and other carbon-based organic matter (mainly affecting COD and BOD) into microbial cells. After being synergistically treated with gel, these microbial cells are spread on the grass felt. After high-density enrichment and localized growth during static culture, the cell wall peptides and other glycopeptide macromolecules secondary secreted on the surface of the cells can be aggregated into large biofilm structures. These biofilm structures can be separated from the water body without adding chemical flocculants. Under normal circumstances, these biofilms are also easily preyed upon by snails (such as field snails and patterned snails) and fish and shrimps. The naturally deposited bacterial complexes in the water body will gradually become nutrients for aquatic plants or algae. The total nitrogen, total phosphorus and some carbon-based pollutants in the water body will be transferred out of the water body in the form of aquatic plants or animals, and can also be directly removed from the water body by physical methods, thereby achieving the goal of water purification. The method of the present invention can basically adopt non-powered operation, has a long barrier-free operation cycle, low operation and maintenance costs, and all pollution factors are fully utilized as resources without generating secondary pollution. It is a technical system that conforms to the development concept of green environmental protection.

[0012] The technical solution adopted by the present invention is as follows: 1. Use plant rhizomes, especially hollow rice or wheat straw, to weave into straw mats.

[0013] The effect is that the biocompatibility of plant rhizome biofibers with microbial colonies is far superior to the currently commonly used materials such as polyethylene (PE), polypropylene (PP), and polystyrene (PS) for environmental protection projects. It is not only conducive to the attachment of microorganisms, but also conducive to the extension, growth, and migration of biofilms. At the same time, the specific surface area of ​​rice straw and wheat straw is also large, and the detached biofilm will not be easily accumulated and blocked and difficult to clean like brush-like and spherical plastic-like fillers. The biofilm formed on the surface of the grass felt is also easy to be eaten by snails, fish, and shrimps, achieving an automatic cleaning effect. The hollow fiber straw is also conducive to the preservation of beneficial microorganisms. In addition, the structural form of the grass felt is also conducive to the replacement of fillers (microbial carriers) without stopping the machine under continuous working conditions.

[0014] 2. The microbial community with water purification function is solidified and grown on the microbial grass mat with the help of gelling agent.

[0015] The beneficial microorganisms include but are not limited to at least one of bacillus, yeast, lactic acid bacteria, and photosynthetic bacteria.

[0016] In some embodiments, a combination of beneficial microorganisms is provided, which is Bacillus subtilis, Bacillus amyloliquefaciens, Pichia pastoris, and Lactobacillus plantarum, or a combination of Bacillus subtilis, Rhodopseudomonas palustris, Schizosaccharomyces cerevisiae, Saccharomyces cerevisiae, and Bifidobacterium.

[0017] The effect is: screening and combining engineered bacterial communities that can convert soluble and insoluble pollutants in water bodies such as ammonia nitrogen, nitrate nitrogen, total phosphorus and other carbon-based organic matter (mainly affecting COD and BOD) into microbial cells. These engineered bacterial communities can use nitrogen, phosphorus and other organic biological pollutants in water bodies to transform into microbial biofilms, or symbiotically generate biofilms and phytoplankton to form bacterial-algal complexes. These biofilms and bacterial-algal complexes can be used as nutrition for aquatic plants and animals, and can also be directly removed from the water body by physical methods. These beneficial microorganisms include but are not limited to: Bacillus, yeast, lactic acid bacteria, and photosynthetic bacteria.

[0018] By fixing the engineered bacterial community on the straw mat, the problem of the bacterial community being only distributed in the flowing water and easily lost, which reduces the working concentration, can be avoided. Especially in the ditch water environment management and the pool environment with large water exchange volume and residence time period, the engineered bacterial community cannot be fixed and grow, and the bacterial community in the flowing water body will be lost in large quantities with the exchange of water. The resulting insufficient bacterial abundance often affects the effect of water body management.

[0019] Through long-term domestication, induction and screening of optimized engineered bacterial communities, not only can water be purified efficiently, but also the problem of self-corrosion and decomposition of natural organic materials such as straw mats can be avoided during operation by inhibiting the growth and metabolism of miscellaneous bacteria that cause the decomposition of straw mats. This can not only extend the service life of the straw mats, but also avoid secondary pollution caused by the decay of the straw mats.

[0020] 3. Synergistic use of gelling agents.

[0021] The expanded and activated engineered bacteria are mixed with the gelling agent, adjusted to the required concentration, and evenly spread on the straw mat. Allow it to stand in the air for 8 to 72 hours at a temperature of 10 to 40°C, and then deploy it in the water body to be treated.

[0022] The gelling agent used includes any one or more of agar, carrageenan, xanthan gum, sodium alginate, gum arabic, polyvinyl alcohol, polyethylene glycol, sodium carboxymethyl starch, sodium carboxymethyl cellulose and modified starch.

[0023] In some embodiments, agar and xanthan gum are combined, and modified tapioca starch and carrageenan are combined.

[0024] The effect is that the engineered bacterial flora used for water purification usually grows and reproduces freely, such as commonly used photosynthetic bacteria, Bacillus subtilis, brewer's yeast, baker's yeast and lactic acid bacteria, which are difficult to adhere to the surface of the filler without the synergistic effect of additives. The gelling agent described in the present invention is not only suitable for the growth and reproduction of the engineered bacterial flora, but also can be activated by evenly spreading and statically culturing the engineered bacterial flora on the grass felt before being put into the water body. Through the regional aggregation growth of the bacterial flora, the polysaccharides and glycopeptide components secreted by the bacterial flora after being put into the water body are easy to form a large visible bacterial film, and these bacterial films are also easy to adhere to floating algae such as Chlorella to form bacterial-algae symbiotic complexes. These bacterial films and bacterial-algae complexes can not only be directly removed from the water body by filtration and sedimentation, but also easily become baits directly eaten by snails, fish and shrimp.

[0025] The present invention has at least the following beneficial effects: The present invention adopts non-powered operation, has a long barrier-free operation cycle, low operation and maintenance costs, fully utilizes pollution factors as resources, and will not produce secondary pollution. It is a technical system that conforms to the development concept of green environmental protection. It solves the technical problems that commonly used microbial fillers often cause filler blockage, filler pile bacteria lack of oxygen and stench, etc., and it is necessary to stop operation, empty sewage, and replace fillers before restarting operation. Not only is the replacement cost very high, the maintenance cycle is long, and secondary pollution will be caused.

[0026] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The microbial biofilm and the bacterial-algal complex grown on the microbial turf mat of Example 1 of the present invention. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below with reference to examples so that those skilled in the art can implement the invention with reference to the description.

[0029] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0030] Example 1 The rice straw was woven into a 1-meter-wide, 4-meter-long, 3-5-cm-thick mat, and the expanded water purification microbial working flora (including Bacillus subtilis ( Bacillus subtilis )、Bacillus amyloliquefaciens( Bacillus amyloliquefaciens )、Pichia pastoris( Komagataellaphaffii ), Lactobacillus plantarum) and gel (agar and xanthan gum), adjust the bacterial concentration to 20 million cfu / ml, evenly spread the mixed bacterial-gel complex on the grass mat, let it stand at room temperature of 25℃ for 48 hours, and then put it into the water body to be treated. Figure 1 Shown are microbial biofilms and bacterial-algal complexes growing on microbial grass mats.

[0031] For example, in the microbial engineering flora, the content of Bacillus subtilis is 60%, the content of Pichia pastoris is 20%, the content of Bacillus amyloliquefaciens is 10%, and the content of Lactobacillus plantarum is 10%.

[0032] The gel contains 2% agar, 2.5% xanthan gum, 5% microbial culture medium, etc., and water is added to make it 100%.

[0033] Example 2 Wheat straw was woven into a 1-meter-wide, 1-meter-long, 5-8-cm-thick mat, and the cultivated water purification microbial working flora (including Bacillus subtilis ( Bacillus subtilis )、Rhodopseudomonas palustris( Rhodopseudomonaspalustris )、Fission yeast( Schizosaccharomycespombe )、Saccharomyces cerevisiae( Saccharomyces cerevisiae )、Bifidobacterium( Bifidobacteriumspp. )) is mixed with a gelling agent (a compound of modified cassava starch and carrageenan), and the bacterial concentration is adjusted to 10 million cfu / ml. The mixed bacterial flora-gelling agent complex is evenly spread on the straw mat, left to stand at room temperature of 35°C for 24 hours, and then released into the water body to be treated.

[0034] For example, in the microbial engineering flora, the content of Bacillus subtilis is 50%, the content of Rhodopseudomonas palustris is 30%, the content of fission yeast is 5%, the content of brewer's yeast is 10%, and the content of Bifidobacterium is 5%.

[0035] The gelling agent contains 5% modified cassava starch, 2% carrageenan, 6% microbial culture medium, etc., which are prepared into 100% by adding water.

[0036] Existing microbial fillers (such as plastics and inorganic materials) are prone to blockage due to the accumulation of microbial colonies, resulting in lack of oxygen and rot in the filler, and frequent shutdowns for cleaning and replacement are required. The present invention uses the straw felt structure (hollow, large specific surface area) woven from plant straw and the characteristics of the bacterial film that can be preyed on by aquatic organisms to avoid bacterial accumulation, maintain the permeability of the filler, and reduce the risk of lack of oxygen and rot.

[0037] Traditional filler replacement requires draining sewage and shutting down for maintenance, which is costly and waste fillers are prone to secondary pollution. The present invention uses biodegradable straw mats, and the biofilm can be naturally transformed or physically removed by the ecological chain, and supports replacement without stopping the machine, reducing operation and maintenance costs and avoiding pollution transfer.

[0038] Free microorganisms in flowing water bodies are easily lost with the water flow, resulting in insufficient abundance of bacterial flora and unstable purification effect. The present invention uses the synergistic effect of gelling agent solidification and straw mat carrier to fix the engineered bacterial flora at a high density on the straw surface and hollow structure, thereby improving the bacterial flora retention rate and ensuring continuous purification efficiency.

[0039] Conventional sewage treatment relies on chemical flocculants, which pose an ecotoxicity risk. The present invention utilizes microbial metabolism and natural flocculation of bacteria-algae complexes, without the need for chemical additives, and pollutants are removed through biochain transformation, achieving green purification.

[0040] Traditional organic fillers (such as wood and bamboo) are easily decomposed and corrupted by miscellaneous bacteria, shortening their service life. The present invention extends the durability of straw mats and avoids secondary pollution caused by self-decomposition by selecting engineered bacterial flora (such as Bacillus and lactic acid bacteria) that inhibit corruption.

[0041] Existing technologies often simply separate pollutants instead of converting them for use. The present invention converts nitrogen, phosphorus and organic matter into biofilm or bacterial-algal complexes, which are directly used as a nutrient source for aquatic plants and animals, thus realizing the resource recycling of pollutants and improving the sustainability of governance.

[0042] In summary, the present invention is applicable but not limited to applications in ponds, reservoirs, streams, ditches, wetlands, sewage treatment plants (stations), tidal flats and other scenarios. It systematically solves the problems of clogging of traditional microbial fillers, high operation and maintenance costs, secondary pollution, bacterial loss and low resource utilization by ecological means. Through carrier structure innovation, directional solidification of bacterial colonies and synergy of the food chain, efficient, low-cost and environmentally friendly water purification can be achieved.

[0043] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and the embodiments. They can be applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily realized.

Claims

1. A method for treating sewage using microbial grass mat, characterized in that: The following steps are involved: Weaving hollow plant rhizomes into grass felt; Mixing beneficial microorganisms with a gelling agent and spreading the mixture on the surface of the grass mat; Leave it at 10-40℃ for 8-72 hours to allow the microorganisms to grow, metabolize and attach to the straw mat; The treated straw mat is laid in the water body to be treated.

2. The method for treating sewage using microbial mat according to claim 1, characterized in that: The plant rhizomes include rice or wheat straw with a hollow structure, which are first woven into a straw mat. The surface of the straw mat is conducive to the attachment and reproduction of microorganisms and the formation of biofilm or bacterial-algae complex communities, and is easy to be preyed on and automatically cleaned by snails, fish and shrimps. At the same time, the straw mat is also conducive to non-stop replacement under continuous working conditions.

3. The method for treating sewage using microbial mat according to claim 1, characterized in that: The gelling agent used includes any one or more of agar, carrageenan, xanthan gum, sodium alginate, gum arabic, polyvinyl alcohol, polyethylene glycol, sodium carboxymethyl starch, sodium carboxymethyl cellulose and modified starch. The gelling agent strengthens the fixation growth of beneficial microorganisms on the straw mat and is beneficial to the migration growth of microbial colonies, especially the growth and filling of hollow parts of rice and wheat straw.

4. The method for treating sewage using microbial mat according to claim 1, characterized in that: The beneficial microorganisms used have the function of transforming nitrogen, phosphorus and other organic biological pollutants in the water into microbial biofilm, or symbiotically generating biofilm and phytoplankton into a bacterial-algal complex; The biofilm and bacterial-algal complex are used as nutrition for aquatic plants and animals, or are directly removed from the water body by physical methods; The beneficial microorganisms include at least one of bacillus, yeast, lactic acid bacteria and photosynthetic bacteria.

5. The method for treating sewage using microbial mat according to claim 1 or 4, characterized in that: Beneficial microorganisms include: a combination of Bacillus subtilis, Bacillus amyloliquefaciens, Pichia pastoris, and Lactobacillus plantarum, or a combination of Bacillus subtilis, Rhodopseudomonas palustris, fission yeast, brewer's yeast, and Bifidobacterium.

6. The method for treating sewage using microbial mat according to claim 3, characterized in that: The gelling agent includes: a compound of agar and xanthan gum, or a compound of modified cassava starch and carrageenan.

7. The method for treating sewage using microbial mat according to claim 3 or 4, characterized in that: After the gel was mixed with the microbial flora, the flora concentration was 5×10 7 ~5×10 9 cfu / ml.

8. The method for treating sewage using microbial mat according to claim 7, characterized in that: The optimal concentration range of bacterial colony is 1×10 8 ~2×10 9 cfu / ml.

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