Method for purifying organic sewage according to strain decomposition and adaptive sequential release

Abstract

The invention relates to a method for purifying organic sewage according to strain decomposition and adaptive sequential release. According to the method, bacillus subtilis, bacillus cereus, streptomyces microflavus and rhodopseudomonas palustris which have a mutual growth promotion effect are firstly released in organic sewage, macromolecular substances such as protein, ester, fiber and starch are firstly decomposed, and rhodotorula mucilaginosa, faecalis coccus and clostridium butyricum are released by adopting a microcapsule slow release method; furthermore, small molecules such as amino acid, glucose, fatty acid and the like are utilized, so that the organic pollutants are finally degraded into small-molecule organic acid, carbon dioxide and water. The method disclosed by the invention is suitable for reducing COD and BOD levels of food industrial wastewater, and has the characteristics of low cost and convenience in manufacturing and use.

Description

Technical Field

[0001] The present invention is a method for purifying organic sewage by decomposing and adaptively releasing according to the order of bacterial strains, belonging to the fields of environmental protection and light industry. Background Art

[0002] Industrial wastewater and domestic sewage contain various organic pollutants. Among them, food industry wastewater is rich in protein, starch, cellulose, esters / fats, and inorganic salts, which are extremely perishable, emit foul odors, pollute water bodies and the environment, and may spread harmful microorganisms. COD and BOD can reflect the content of pollutants such as protein, starch, esters / fats, etc. Other indicators for measuring pollutants also include the content of suspended substances, pH, etc.

[0003] In terms of sewage treatment, according to the cleanliness level of the treated water, there are sedimentation methods, adsorption methods, redox methods, microbial methods, aeration methods, membrane separation, ion exchange, etc. Among them, the microbial method mainly uses single bacterial strains or composite bacterial strains to decompose organic wastewater. The reported available bacterial strains include lactic acid bacteria, actinomycetes, bacillus subtilis, yeast, photosynthetic bacteria, etc.

[0004] Bacillus subtilis: Facultative anaerobe, with an optimum temperature of 25 - 37 °C and an optimum pH of 5.0 - 7.0. It can utilize substrates such as protein, esters / fats, etc., and produce amino acids, fatty acids, ammonia nitrogen, etc.; Bacillus cereus: Facultative anaerobe, with an optimum temperature of 28 - 35 °C and an optimum pH of 6.0 - 7.0. It can utilize substrates such as esters / fats, starch, etc., and produce fatty acids, glucose, etc.; Streptomyces microflavus: Aerobe, with an optimum temperature of 25 - 30 °C and an optimum pH of 5 - 7. It can utilize substrates such as starch, cellulose, etc., and produce small molecule substances such as glucose; Rhodopseudomonas palustris: Facultative anaerobe, with an optimum temperature of 30 - 36 °C and an optimum pH of 5.0 - 8.0. It can decompose small molecule organic acids, inorganic salts, etc., and produce hydrogen, carbon dioxide, etc.; Rhodotorula glutinis: Facultative anaerobe, with an optimum temperature of 28 - 35 °C and an optimum pH of 2.0 - 7.0. It can hydrolyze the plant cuticle, utilize substrates such as protein, glucose, etc., and produce organic acids, carbon dioxide, etc.; Coprococcus: Facultative anaerobe, with an optimum temperature of 35 - 38 °C and an optimum pH of 5.0 - 7.5. It can utilize hemicellulose, amino acids, etc., and produce soluble sugars, organic acids, etc.; Clostridium butyricum: Anaerobe, with an optimum temperature of 25 - 37 °C and an optimum pH of 4.0 - 9.8. It can utilize soluble sugars, starch, etc., and produce organic acids, carbon dioxide, etc.

[0005] Bacillus subtilis, Bacillus cereus, Streptomyces microflavus, and Rhodopseudomonas palustris can symbiotically coexist and promote each other's growth. Among them, Bacillus cereus and Streptomyces microflavus can preferentially degrade carbohydrates to produce glucose, providing nutrients for other bacterial strains. Bacillus subtilis can deeply decompose most of the organic components of protein and esters / fats.

[0006] Enterococcus faecalis, Rhodotorula glutinis, and Clostridium butyricum are relatively tolerant to low pH values. Rhodotorula glutinis and Clostridium butyricum can utilize a wider range of nutrients. Enterococcus faecalis is widely present in the natural environment, has relatively strong adaptability, and can tolerate ammonia nitrogen conditions.

[0007] Encapsulation materials such as gum arabic, gelatin, sodium alginate, and sodium carboxymethylcellulose have different release rates, but their compound use is cumbersome and costly. The embedding capsules made of chitosan, acetic acid, and calcium chloride have a capsule particle size that can affect the slow-release rate. Small capsules have a faster release rate than large capsules, and they are suitable for making capsules with the ability to release strains at different time periods.

[0008] Design an appropriate combination of dominant strains. After a one-time release, first release several combinations of strains that can adapt to each other, initially decompose macromolecular proteins, cellulose, starch, and esters to produce secondary components such as amino acids, glucose, organic acids, and ammonia nitrogen. After a period of time, release several strains that adapt to the secondary component conditions, and further degrade them into water, carbon dioxide, etc., to achieve the purpose of deeply treating organic sewage. Summary of the Invention

[0009] The purpose of the present invention is to provide a method for purifying organic sewage by sequentially releasing according to the decomposition and adaptability of strains. This method can have a good effect on reducing COD and BOD in food industry wastewater.

[0010] To achieve the above purpose, the composite strains provided by the present invention include Bacillus subtilis, Bacillus cereus, Streptomyces microflavus, Rhodotorula glutinis, Enterococcus faecalis, Clostridium butyricum, and Rhodopseudomonas palustris.

[0011] Use chitosan, acetic acid, and calcium chloride to make small-particle-size embedding capsules to embed Bacillus subtilis, Bacillus cereus, Streptomyces microflavus, and Rhodopseudomonas palustris, and their particle size is 1.5 - 2.5 mm.

[0012] Use chitosan, acetic acid, and calcium chloride to make large-particle-size single-crosslinked embedding capsules to embed Rhodotorula glutinis, Enterococcus faecalis, and Clostridium butyricum, and then use sodium sulfate for secondary crosslinking of the capsules to obtain large-particle-size secondary crosslinked embedding, and their particle size is 2.0 - 3.5 mm.

[0013] Compound the obtained small-particle-size embedding capsules with large-particle-size secondary crosslinked embedding capsules to obtain a composite sequential release capsule-embedded strain.

[0014] The present invention also provides a preparation method of the composite bacterial agent, and the method includes the following steps:

[0015] (1) Activate the composite strains of the present invention for two generations, centrifuge, collect the bacterial cells, and resuspend the bacterial cells with a protective agent;

[0016] (2) Inoculate into the combined culture medium at an inoculation amount of 2% and conduct fermentation culture;

[0017] (3) Centrifuge the combined culture bacterial liquid at 4000 rpm for 10 min;

[0018] (4) Mix the bacterial sludge with a certain amount of freeze-drying protectants such as glycerol, trehalose, and skim milk according to a certain ratio;

[0019] (5) Take a certain amount of sodium alginate and shake it on a shaker until the sodium alginate is completely dissolved;

[0020] (6) Mix the above-mentioned bacterial sludge and protectant suspension with the sodium alginate solution evenly according to a certain ratio;

[0021] (7) Take a certain amount of chitosan, add 2% acetic acid, and shake it on a shaker until the chitosan is completely dissolved;

[0022] (8) Take a certain amount of calcium chloride and dissolve it in distilled water;

[0023] (9) Mix the completely dissolved chitosan acetic acid solution with the calcium chloride solution and stir until it is uniform;

[0024] (10) Inject the mixed core material into the chitosan acetic acid and calcium chloride mixture with a syringe of appropriate size and crosslink for a certain time to form microbial controlled-release capsules with particle sizes of 1.5 - 2.5 mm and 2.0 - 3.5 mm;

[0025] (11) Wash the small particle size embedded capsules with distilled water;

[0026] (12) Conduct double crosslinking on the large capsules with 2% sodium sulfate solution and then wash them with distilled water;

[0027] (13) Freeze-dry the obtained small particle size embedded capsules and the large particle size secondary crosslinked embedded capsules for long-term preservation.

[0028] In the method for degrading food industrial wastewater provided by the present invention, the fermentation conditions are 33°C, pH 7, inoculation amount 3%, time 7 d, and an appropriate amount of 1% calcium chloride solution can be added.

[0029] In the method for degrading food industrial wastewater provided by the present invention, the freeze-dried bacterial agent can be stored for 2 years. Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 Schematic diagram of the mutual promotion among Bacillus subtilis, Bacillus cereus, Streptomyces microflavus and Rhodopseudomonas palustris

[0032] Figure 2 Schematic diagram of the degradation ability with the sequential addition of composite strains

[0033] Figure 3 Small particle size embedded capsules and large particle size secondary cross-linked embedded capsules

[0034] Figure 4 Schematic diagram of treating tofu yellow slurry water (left is after treatment, right is untreated)

[0035] Figure 5 Schematic diagram of treating brine wastewater (left is after treatment, right is untreated)

[0036] Figure 6 Schematic diagram of treating fruit and vegetable wastewater (left is after treatment, right is untreated) Specific implementation manners

[0037] The following specific implementation manner examples are used to illustrate the present invention for easy understanding and operation, but in no way limit the scope of the present invention. Unless otherwise specified, the following reagents or bacterial agents are all commercially available reagents or bacterial agents.

[0038] Example 1

[0039] The water purification of the present invention includes:

[0040] (1) Using tofu yellow slurry water as the wastewater to be treated;

[0041] (2) Adjusting the pH of the tofu yellow slurry water to 7, then adding 3% of the composite sequential release capsule-embedded strains and an appropriate amount of 1% calcium chloride solution;

[0042] (3) Controlling the temperature at 33°C and fermenting for 7 days;

[0043] (4) The COD degradation rate reaches 86.98%, the BOD degradation rate reaches 84.72%, and the suspended solid removal rate reaches 95.43%.

[0044] Example 2

[0045] The water purification of the present invention includes:

[0046] (1) Using fruit and vegetable slurry water as the wastewater to be treated;

[0047] (2) Adjusting the pH of the fruit and vegetable water to 7, then adding 3% of the composite sequential release capsule-embedded strains and an appropriate amount of 1% calcium chloride solution;

[0048] (3) Controlling the temperature at 33°C and fermenting for 7 days;

[0049] (4) The COD degradation rate reaches 88.06%, the BOD degradation rate reaches 85.87%, and the suspended solid removal rate reaches 96.94%.

[0050] Example 3

[0051] The water purification of the present invention includes:

[0052] (1) Using the braised waste soup as the wastewater to be treated;

[0053] (2) Adjusting the pH of the braised waste soup to 7, then adding 3% of the composite sequential release capsule-embedded bacteria and an appropriate amount of 1% calcium chloride solution;

[0054] (3) Controlling the temperature at 33°C and fermenting for 7 days;

[0055] (4) The COD degradation rate reaches 85.87%, the BOD degradation rate reaches 83.46%, and the suspended solid removal rate reaches 92.57%.

[0056] Although the present invention has been described in detail with general descriptions and specific examples above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention fall within the scope of the present invention claimed.

Claims

1. A method for purifying organic sewage by releasing it according to the decomposition and adaptability sequence of bacterial strains, characterized in that after 7 bacterial strains are embedded and compounded, and according to the sequence of release of the bacterial strains, the organic matters with different molecular sizes in the sewage are decomposed purposefully and step by step to achieve the purpose of purifying organic sewage.

2. Use chitosan, acetic acid, and calcium chloride to make small-sized embedded capsules, and embed Bacillus subtilis, Bacillus cereus, Streptomyces microflavus, and Rhodopseudomonas palustris.

3. Use chitosan, acetic acid, and calcium chloride to make large-sized primary cross-linked embedded capsules, embed Rhodotorula mucilaginosa, Coprococcus, and Clostridium butyricum, and then use sodium sulfate for secondary cross-linking of the capsules to obtain large-sized secondary cross-linked embedded capsules.

4. Compound the small-sized embedded capsules obtained in step 2 with the large-sized secondary cross-linked embedded capsules obtained in step 3 to obtain a composite sequential release capsule-embedded bacterial strain.

5. The small-sized embedded capsule described in claim 2, with a particle size of 1.5 - 2.5 mm.

6. The large-sized secondary cross-linked embedded capsule obtained in claim 3, with a particle size of 2.0 - 3.5 mm.

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