Method for treating slaughterhouse wastewater

Abstract

The present application relates to a kind of slaughter wastewater treatment methods, in the slaughter wastewater treatment process comprising anaerobic unit and aerobic unit, with the first aerobic unit as the object, first add acinetobacter pittii ( Acinetobacter pittii ) Bacteria solution, after a period of operation, change to add microbacterium parvum ( Microbacterium kitamiense ) Bacteria solution, realize the efficient treatment of slaughter wastewater.The present application method can realize the simultaneous efficient removal of ammonia nitrogen, total nitrogen, total phosphorus, COD and oil in wastewater without changing the original structure.

Description

Technical Field

[0001] This invention belongs to the field of water pollution control technology, specifically relating to a method for treating slaughterhouse wastewater. Background Technology

[0002] Slaughterhouse wastewater is a type of livestock wastewater, belonging to high-concentration organic wastewater. It mainly originates from pen washing, rinsing, slaughtering, and other factory floor washing, scalding, evisceration, by-product processing, and oil washing, and is classified as high-nitrogen, high-phosphorus, and high-organic wastewater. Nitrogen is primarily in the form of organic matter or NH4+. + Phosphorus exists primarily in the form of PO4. 3- The problem exists. With the promulgation of the "Water Pollutant Discharge Standard for Slaughtering and Meat Processing Industry" (draft for comments), the discharge limits for ammonia nitrogen, total nitrogen, and total phosphorus in wastewater have become more stringent. However, most current treatment processes are designed for the original "Water Pollutant Discharge Standard for Meat Processing Industry" (GB 13457-1992) or "Integrated Wastewater Discharge Standard" (GB8978-1996), and do not consider the simultaneous removal of ammonia nitrogen, total nitrogen, and total phosphorus. Even if some processes have nitrogen and phosphorus removal capabilities, the nitrogen and phosphorus removal effects are not ideal.

[0003] Currently, commonly used slaughterhouse wastewater treatment processes are mostly biological processes or combinations of biological processes, such as ABR-CASS, AFBR-AMBR, DAF-UASB, SBR-DAF-UV, UASB-SBR, UASB-A / O, hydrolysis acidification-contact oxidation, and hydrolysis acidification-A / O processes. Compared to physical and chemical methods, biological methods have advantages such as safety, high efficiency, and low cost, making them a commonly used treatment technology in wastewater treatment systems. For biological nitrogen and phosphorus removal technologies, finding highly efficient nitrogen and phosphorus removal bacteria is one of the key factors for their stable operation.

[0004] CN113481131A discloses a composite polyphosphate-accumulating agent, its preparation method, and its application. This composite polyphosphate-accumulating agent is prepared by mixing Janibacter sp. PAOS56, Fictibacillus sp. PAO25, and Microbacterium sp. PAO22 in a 1:1:1 ratio. It can be applied to remove phosphorus from starch wastewater, dairy wastewater, slaughtering and meat processing wastewater, and oily wastewater, effectively reducing their phosphorus content. However, this agent does not have the ability to remove ammonia nitrogen or total nitrogen, and the dosage is relatively large.

[0005] CN112592853A discloses a microbial agent containing *Alcaligenes faecalis* and its application. The microbial agent contains at least 5.0 × 10⁻⁶ bacteria. 8The microbial agent comprises *Alcaligenes faecalis* powder (CFU / g) and a carrier, with a mass ratio of 1:50–100. This microbial agent exhibits the ability to rapidly and efficiently remove COD, ammonia nitrogen, and total nitrogen from slaughterhouse wastewater. However, the dosage is relatively high, requiring concentrations of 80-100 ppm in anoxic tanks and 180-200 ppm in aerobic tanks, and it lacks the ability to remove total phosphorus.

[0006] CN115745276A discloses a method for treating slaughterhouse wastewater using biological contact oxidation, comprising the following steps: (1) filtering and settling the slaughterhouse wastewater, and then injecting the settled wastewater into an anaerobic tank; (2) adding anaerobic bacteria to the anaerobic tank, and injecting the anaerobic wastewater into an aerobic tank after anaerobic treatment; (3) aerating the wastewater in the aerobic tank to obtain the treated slaughterhouse wastewater. This invention features high biological activity, good treatment effect on slaughterhouse wastewater, high load capacity, and strong shock resistance, effectively improving wastewater treatment efficiency. The anaerobic bacteria provided by this invention include Bacillus subtilis, Bacillus licheniformis, Bacillus pumilus, and Lactobacillus. On the one hand, the composition of the bacteria is relatively complex; on the other hand, it needs to be matched with an anaerobic environment, resulting in high treatment costs. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for treating slaughterhouse wastewater. This method can efficiently remove ammonia nitrogen, total nitrogen, total phosphorus, COD, and oil from wastewater simultaneously without altering the original structures.

[0008] The present invention provides a method for treating slaughterhouse wastewater, comprising the following:

[0009] In the slaughterhouse wastewater treatment process that includes anaerobic and aerobic units, taking the primary aerobic unit as the target, Acinetobacter pittii PA6 bacterial solution is first added. After running for a period of time, Microbacterium kitamiense PR bacterial solution is added to achieve efficient treatment of slaughterhouse wastewater.

[0010] In this invention, *Acinetobacter pittii* PA6 was deposited on June 27, 2022, at the China General Microbiological Culture Collection Center (CGMCC), accession number CGMCC No. 25181, located at Institute of Microbiology, Chinese Academy of Sciences, No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing. The main morphological characteristics of this bacterium are as follows: after culturing on TSA medium at 37°C for 18 hours, the colonies are yellow, round, moist, opaque, and have neat edges. Under a microscope, the bacteria are rod-shaped, 0.3-0.5 μm × 0.4-1.0 μm, arranged singly or in pairs, and are Gram-negative.

[0011] In this invention, *Microbacterium kitamiense* PR was deposited on June 27, 2022, at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 25182, located at Institute of Microbiology, Chinese Academy of Sciences, No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing. The main morphological characteristics of this bacterium are as follows: when cultured on TSA medium at 30°C for 3 days, the colonies are yellow, round, moist, opaque, and have neat edges. Under a microscope, the bacteria appear as short rods, 0.4-0.6 μm × 0.7-1.6 μm, arranged singly or in pairs, and are Gram-positive.

[0012] In this invention, the preparation methods for Acinetobacter piezoides PA6 bacterial suspension and Microbes kiwi PR bacterial suspension are as follows: the preserved strains are inoculated into LB liquid medium and cultured at 25-35℃, pH 6-9, stirring speed 150-240 rpm, under aerobic conditions until OD. 660 A concentration of 0.7 or higher, preferably 0.8-1.2, is sufficient for use as a bacterial culture medium. The LB medium formula is: NaCl 5-15 g / L, peptone 5-15 g / L, yeast extract 3-8 g / L.

[0013] In this invention, the total amount of the two bacterial solutions added is less than 5.0% based on the volume ratio of the bacterial solution to the system, preferably 0.5-3.0%. Specifically, *Acinetobacter piezoides* PA6 and *Microbacterium kiwifruit* PR are added at a volume ratio of 1:1-5.

[0014] In this invention, after adding Acinetobacter pittii PA6, the COD of the primary aerobic unit is further controlled to be greater than 1500 mg / L, preferably 2000-3000 mg / L. This can be achieved by supplementing a carbon source, preferably at least one of sodium acetate, sodium succinate, etc.

[0015] In this invention, after adding Acinetobacter petresii PA6 bacterial solution, the solution is changed to Microbacterium kiwifruit PR bacterial solution after running for 1-5 hours.

[0016] In this invention, the wastewater treatment process can be any one of the following: hydrolysis acidification / UASB / ABR-SBR (primary aerobic unit) process, hydrolysis acidification / UASB / ABR-O (primary aerobic unit)-AO process, or two-stage AO process (i.e., primary anaerobic unit - primary aerobic unit - secondary anaerobic unit - secondary aerobic unit), wherein the primary aerobic unit refers to the SBR and primary O stage in the above processes. Furthermore, the sludge age of the SBR is maintained at 10-30 days, preferably 15-25 days, or the sludge age of the primary O stage is maintained at 7-25 days, preferably 10-20 days.

[0017] In this invention, the wastewater treatment process includes the following treatment conditions for the primary aerobic unit: temperature 20-35℃, preferably 20-28℃; pH value 7.5-9, preferably 8-9; and dissolved oxygen maintained at ≥1 mg / L, preferably 1-2 mg / L. Other treatment conditions are the same as those in the original process.

[0018] In this invention, the slaughterhouse wastewater contains ammonia nitrogen, total nitrogen, total phosphorus, COD, and animal and vegetable oils.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) Select the first-level aerobic unit to add the bacterial solution provided by the present invention, so that polyphosphate-accumulating bacteria do not need to release phosphorus in the anaerobic unit, which solves the contradiction between nitrifying bacteria and polyphosphate-accumulating bacteria sludge age in traditional denitrification and phosphorus removal methods. There is no need to adjust the anaerobic unit, and the simultaneous and efficient removal of ammonia nitrogen, total nitrogen, total phosphorus, COD and oil in slaughter wastewater is achieved.

[0021] (2) By sequentially adding Acinetobacter pituitaria PA6 and Microbes pr, the individual properties of the strains are utilized while their synergistic advantages are fully leveraged to improve the original microbial composition, enhance the biochemical treatment effect, and achieve efficient removal of pollutants. The performance is significantly improved compared to adding an equal amount of a single strain.

[0022] (3) This invention can achieve efficient removal of COD, ammonia nitrogen, total nitrogen, total phosphorus and oil in slaughterhouse wastewater by selecting the structure, adding bacterial solution and adjusting parameters without changing the original structure. It can meet the requirements of the new standard without the need for external physicochemical methods. It is simple to operate and has low operating costs. Detailed Implementation

[0023] The technical solution and its effects of the present invention will be described in detail below with reference to specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0024] Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following examples were purchased from conventional biochemical reagent stores.

[0025] In this embodiment of the invention, total phosphorus was determined using the ammonium molybdate spectrophotometric method (GB11893-89); ammonia nitrogen was determined using the Nessler's reagent spectrophotometric method (HJ535-2019); total nitrogen was determined using the alkaline potassium persulfate digestion ultraviolet spectrophotometric method (HJ636-2012); and COD was determined using the potassium dichromate method (HJ828-2017). The detection method for animal and vegetable oils was infrared spectrophotometry (HJ637-2018).

[0026] The LB liquid culture medium used in this embodiment of the invention has the following formulation: NaCl 10 g / L, peptone 10 g / L, and yeast extract 5 g / L. The solid culture medium is the liquid culture medium with 20 g / L agar added.

[0027] The preparation methods for the two bacterial cultures in this embodiment of the invention are as follows: Preserved Acinetobacter piezoides PA6 and Microbes pr are inoculated into LB liquid medium and cultured under aerobic conditions at 30°C, pH 8.0, 150-240 rpm until OD is reached. 660 The concentration was set at 0.8-1.2 to obtain PA6 and PR bacterial solutions for later use.

[0028] In this invention, the slaughterhouse wastewater contains ammonia nitrogen, total nitrogen, total phosphorus, COD, and animal and vegetable oils. The ammonia nitrogen concentration is no higher than 200 mg / L, the total nitrogen concentration is no higher than 250 mg / L, the total phosphorus concentration is no higher than 35 mg / L, the COD concentration is 1000-4000 mg / L, and the animal and vegetable oil concentration is no higher than 200 mg / L.

[0029] Example 1

[0030] The water quality of the slaughterhouse wastewater to be treated is as follows: COD 2000 mg / L, ammonia nitrogen 110 mg / L, total nitrogen 120 mg / L, total phosphorus 28 mg / L, and animal and vegetable oils 150 mg / L.

[0031] The original wastewater treatment process was a hydrolysis-acidification-SBR process, where the anaerobic unit was hydrolysis-acidification and the primary aerobic unit was SBR. The aerobic unit's treatment conditions were: temperature 25℃, pH 7.5, and dissolved oxygen 1-2 mg / L. The anaerobic unit's treatment conditions were: temperature 35℃, pH 6.5, and dissolved oxygen below 0.5 mg / L. Before adopting the method of this invention, the treatment results were: COD 55 mg / L, ammonia nitrogen 8.0 mg / L, total nitrogen 78 mg / L, total phosphorus 17 mg / L, and animal and vegetable oils 8.0 mg / L.

[0032] Taking the SBR section as an example, Acinetobacter piterum PA6 bacterial solution was first added, followed by sodium acetate to achieve a COD of 2500 mg / L. After running for 2 hours, Acinetobacter kiwifruit PR bacterial solution was then added. The total dosage of the two bacterial solutions was 2.5% by volume, with the volume ratio of Acinetobacter piterum PA6 to Acinetobacter kiwifruit PR bacterial solution being 1:3. The sludge age was 15 days.

[0033] The treatment results were as follows: COD 49 mg / L, ammonia nitrogen 3.8 mg / L, total nitrogen 14 mg / L, total phosphorus 0.68 mg / L, and animal and vegetable oils 1.2 mg / L.

[0034] Example 2

[0035] The water quality of the slaughterhouse wastewater to be treated is as follows: COD 3000 mg / L, ammonia nitrogen 180 mg / L, total nitrogen 220 mg / L, total phosphorus 35 mg / L, and animal and vegetable oil 155 mg / L.

[0036] The original wastewater treatment process was a hydrolysis-acidification-OAO process, where the anaerobic units consisted of hydrolysis-acidification and stage A, and the aerobic units consisted of a primary O stage and a secondary O stage. The primary aerobic unit refers to the primary O stage. The treatment conditions for the aerobic units were: temperature 30℃, pH 8.5, and dissolved oxygen 1-2 mg / L. The treatment conditions for the anaerobic units were: temperature 25℃, pH 7.5, and dissolved oxygen below 0.5 mg / L. The treatment results before adopting the method of this invention were: COD 49 mg / L, ammonia nitrogen 3.0 mg / L, total nitrogen 25 mg / L, total phosphorus 22 mg / L, and animal and vegetable oils 0.80 mg / L.

[0037] Taking the primary O stage as the target, Acinetobacter piterum PA6 bacterial solution was first added, followed by sodium acetate to achieve a COD of 3000 mg / L. After 3 hours of operation, the solution was switched to Microbacterium kiwifruit PR bacterial solution. The total dosage of the two bacterial solutions was 3.5% by volume, with the volume ratio of Acinetobacter piterum PA6 to Microbacterium kiwifruit PR bacterial solution being 1:5. The sludge age was 15 days.

[0038] The treatment results were as follows: COD 44 mg / L, ammonia nitrogen 1.5 mg / L, total nitrogen 13 mg / L, total phosphorus 0.41 mg / L, and animal and vegetable oils 0.52 mg / L.

[0039] Example 3

[0040] The water quality of the slaughterhouse wastewater to be treated is as follows: COD 1500 mg / L, ammonia nitrogen 80 mg / L, total nitrogen 115 mg / L, total phosphorus 32 mg / L, and animal and vegetable oil 170 mg / L.

[0041] The water treatment process is a hydrolysis-acidification-SBR process, where the anaerobic unit is hydrolysis-acidification and the primary aerobic unit is SBR. The treatment conditions for the aerobic unit are: temperature 28℃, pH 9.0, and dissolved oxygen 1-2 mg / L. The treatment conditions for the anaerobic unit are: temperature 25℃, pH 7.0, and dissolved oxygen below 0.5 mg / L. Before using the method of this invention, the treatment results were: COD 65 mg / L, ammonia nitrogen 11 mg / L, total nitrogen 55 mg / L, total phosphorus 13 mg / L, and animal and vegetable oils 6.5 mg / L.

[0042] Using an SBR (Self-Regulating Bacterial Reactor) as the model, Acinetobacter pittii PA6 bacterial solution was first added, along with sodium acetate to achieve a COD of 2000 mg / L. After 2 hours of operation, Kitamibacter PR bacterial solution was then added. The total dosage of both bacterial solutions was 1.5% by volume, with the volume ratio of Acinetobacter pittii PA6 to Kitamibacter PR bacterial solution being 1:1. The sludge age was 10 days.

[0043] The treatment results were as follows: COD 55 mg / L, ammonia nitrogen 2.0 mg / L, total nitrogen 24 mg / L, total phosphorus 0.33 mg / L, and animal and vegetable oils 2.3 mg / L.

[0044] Example 4

[0045] Same as Example 1, except that sodium succinate was used to regulate COD after adding Acinetobacter pituitaria PA6 bacterial solution. The treatment results were: COD 45 mg / L, ammonia nitrogen 6.6 mg / L, total nitrogen 18 mg / L, total phosphorus 0.82 mg / L, and animal and vegetable oils 1.3 mg / L.

[0046] Example 5

[0047] Same as Example 1, except that COD was not adjusted after adding Acinetobacter piezophyllum PA6 bacterial solution. The results after treatment were: COD 43 mg / L, ammonia nitrogen 1.2 mg / L, total nitrogen 23 mg / L, total phosphorus 11 mg / L, and animal and vegetable oil 0.46 mg / L.

[0048] Comparative Example 1

[0049] Same as Example 1, except that only Acinetobacter piezoides PA6 bacterial solution was added, and the amount added was the same as the total amount of bacterial solution added. The treatment results were: COD 50 mg / L, ammonia nitrogen 4.0 mg / L, total nitrogen 44 mg / L, total phosphorus 8.8 mg / L, and animal and vegetable oils 1.1 mg / L.

[0050] Comparative Example 2

[0051] Same as Example 1, except that only *Bacillus kiwifruit* PR bacterial solution was added, and the amount added was the same as the total amount of bacterial solution added. The results after treatment were: COD 48 mg / L, ammonia nitrogen 3.5 mg / L, total nitrogen 32 mg / L, total phosphorus 6.1 mg / L, and animal and vegetable oils 9.8 mg / L.

[0052] Comparative Example 3

[0053] Same as Example 1, except that the bacterial solution was added to the hydrolysis and acidification section. The results after treatment were: COD 55 mg / L, ammonia nitrogen 8.0 mg / L, total nitrogen 75 mg / L, total phosphorus 17 mg / L, and animal and vegetable oils 8 mg / L.

[0054] Comparative Example 4

[0055] Same as Example 2, except that the bacterial solution was added to the second aerobic stage. The results after treatment were: COD 45 mg / L, ammonia nitrogen 8.0 mg / L, total nitrogen 78 mg / L, total phosphorus 17 mg / L, and animal and vegetable oils 0.8 mg / L.

Claims

1. A method for treating slaughterhouse wastewater, characterized in that... include: In slaughterhouse wastewater treatment processes that include anaerobic and aerobic units, taking the primary aerobic unit as the target, Acinetobacter piezoides is first added. Acinetobacter pittii After running the bacterial culture for a period of time, switch to *Microbacterium chrysogenum* (Bacillus subtilis). Microbacterium kitamiense The bacterial solution enables efficient treatment of slaughterhouse wastewater.

2. The method according to claim 1, characterized in that: The Acinetobacter pitera mentioned is Acinetobacter pitera ( Acinetobacter pittii PA6, accession number CGMCC No. 25181.

3. The method according to claim 1, characterized in that: The aforementioned *Microbacterium kiwi* is *Microbacterium kiwi* ( Microbacterium kitamiense )PR, with accession number CGMCC No.25182.

4. The method according to claim 1, 2 or 3, characterized in that: The preparation methods for Acinetobacter piezoides PA6 bacterial suspension and Microbacterium kiwifruit PR bacterial suspension are as follows: The preserved strains are inoculated into LB liquid medium and cultured at 25-35℃, pH 6-9, stirring speed 150-240 rpm under aerobic conditions until OD... 660 It is above 0.

7.

5. The method according to claim 4, characterized in that: Cultured to OD 660 It ranges from 0.8 to 1.

2.

6. The method according to claim 1, characterized in that: The total dosage of the two bacterial solutions, calculated as the volume ratio of the bacterial solution to the treatment system, is less than 5.0%.

7. The method according to claim 6, characterized in that: The total dosage of the two bacterial solutions is 0.5-3.0% of the volume of the bacterial solution in the treatment system.

8. The method according to claim 1, 6, or 7, characterized in that: Acinetobacter pituitaria PA6 and Microbacterium kiwi PR were added at a volume ratio of 1:1-5 for the bacterial suspension.

9. The method according to claim 1, characterized in that: After adding Acinetobacter piezophyllum, the COD of the primary aerobic unit was further adjusted to be greater than 1500 mg / L.

10. The method according to claim 9, characterized in that: Further adjust the COD of the primary aerobic unit to 2000-3000 mg / L.

11. The method according to claim 9 or 10, characterized in that: COD is regulated by supplementing a carbon source, which is at least one of sodium acetate and sodium succinate.

12. The method according to claim 1, 2 or 3, characterized in that: After adding Acinetobacter petresin PA6, run for 1-5 hours and then switch to Microbezoar PR.

13. The method according to claim 1, characterized in that: During the operation of the primary aerobic unit, the dissolved oxygen level should be maintained at ≥1 mg / L.

14. The method according to claim 13, characterized in that: Maintain dissolved oxygen at 1-2 mg / L.

15. The method according to claim 1, characterized in that: The wastewater treatment process is any one of the following: hydrolysis acidification / UASB / ABR-SBR process, hydrolysis acidification / UASB / ABR-OAO process, or two-stage AO process, wherein the primary aerobic unit refers to the SBR or primary O stage in the aforementioned processes.

16. The method according to claim 15, characterized in that: Maintain the sludge age of the SBR at 10-30 days, or maintain the sludge age of the primary O stage at 7-25 days.

17. The method according to claim 16, characterized in that: Maintain the sludge age of the SBR at 15-25 days; or maintain the sludge age of the primary O stage at 10-20 days.

18. The method according to claim 1, characterized in that: In the wastewater treatment process, the treatment conditions of the primary aerobic unit are: temperature 20-35℃ and pH value 7.5-9.

19. The method according to claim 18, characterized in that: The temperature is 20-28℃, and the pH value is 8-9.

20. The method according to claim 1, characterized in that: The slaughterhouse wastewater contains ammonia nitrogen, total nitrogen, total phosphorus, COD, and animal and vegetable oils.