Method for treating fermentation wastewater

Abstract

The application discloses a fermentation wastewater treatment method. The fermentation wastewater treatment method comprises the following steps: adding filamentous fungi and green algae into fermentation wastewater generated after fermentation treatment of kitchen garbage to carry out fermentation culture, then carrying out solid-liquid separation, and extracting oil from the separated solid. The filamentous fungi comprise Trichoderma harzianum, and the green algae comprise one or more selected from the group consisting of Chlorella vulgaris, Chlorella sp., Haematococcus pluvialis, Leptolyngbya sp., Agmenellum sp. and Comatulicium sp. The fermentation wastewater treatment method can produce oil while treating fermentation wastewater, and reduces the cost of fermentation wastewater treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for treating fermentation wastewater, in particular a method for producing oil based on fermentation wastewater. BACKGROUND

[0002] The fermentation wastewater, in particular the wastewater produced after fermentation of kitchen garbage to produce lactic acid, is a high-concentration organic wastewater with high COD content. The main excessive indexes include COD (chemical oxygen demand), TN (total nitrogen), TP (total phosphorus), ammonia nitrogen and BOD (biochemical oxygen demand), etc. If directly discharged into the external environment, it will seriously pollute the water body and the environment.

[0003] There are currently reports on the treatment and reuse of fermentation wastewater. For example, patent CN105417844A discloses a fermentation wastewater treatment method, which includes the following treatment steps: centrifugal separation of fermentation wastewater by a centrifugal machine into a clear liquid and a thick liquid, wherein the biomass concentration of the thick liquid is higher than that of the clear liquid; the thick liquid is sent to a drying tower for atomization drying to obtain dry powder, which can be used as biological feed or raw material for biological feed; the clear liquid is sent to a sewage treatment system, and the clear liquid is discharged after adjusting the pH to neutral and then being subjected to biochemical treatment in the sewage treatment system. However, in this method, the clear liquid still contains high contents of COD, TN, TP, ammonia nitrogen and BOD, which need to be further subjected to biochemical treatment in the sewage treatment system. Although there are also schemes for treating fermentation wastewater using bacteria, the cost of traditional bacterial treatment of fermentation wastewater is usually high.

[0004] The above information disclosed in the background section is only intended to enhance the understanding of the background of the present application, and therefore it can include information that does not constitute the prior art known to those of ordinary skill in the art. SUMMARY

[0005] The present application provides a method for treating fermentation wastewater, which can produce oil while treating fermentation wastewater, thereby reducing the cost of fermentation wastewater treatment.

[0006] The present application adopts the following technical solutions:

[0007] A method for treating fermentation wastewater, comprising: adding filamentous fungi and green algae to fermentation wastewater produced after fermentation treatment of kitchen garbage for fermentation culture, and then performing solid-liquid separation to extract oil from the separated solid.

[0008] In a preferred embodiment, the filamentous fungi include Trichoderma harzianum.

[0009] In a preferred embodiment, the green algae include a combination of one or more selected from Chlorella vulgaris, Chlorella sp., Haematococcus pluvialis, Leptolyngbya sp., Agmenellum meneghinianum and Cladophora sp.

[0010] In a preferred embodiment, the filamentous fungus is added in an amount of 0.5 x 10 7 ~1.5 x 10 7 / mL. The filamentous fungus can be added in an amount of 0.5 x 10 7 / mL, 0.6 x 10 7 / mL, 0.7 x 10 7 / mL, 0.8 x 10 7 / mL, 0.9 x 10 7 / mL, 1.0 x 10 7 / mL, 1.1 x 10 7 / mL, 1.2 x 10 7 / mL, 1.3 x 10 7 / mL, 1.4 x 10 7 / mL, or 1.5 x 10 7 / mL. In a more preferred embodiment, the filamentous fungus is added in an amount of 0.8 x 10 7 / mL ~ 1.2 x 10 7 / mL. In a more preferred embodiment, the filamentous fungus is added in an amount of 0.9 x 10 7 / mL ~ 1.2 x 10 7 / mL. In a particular and preferred embodiment, the filamentous fungus is added in an amount of 1 x 10 7 / mL.

[0011] In a preferred embodiment, the green algae is added in an amount of 0.5 x 10 7 ~1.5 x 10 7 / mL. The green algae can be added in an amount of 0.5 x 10 7 / mL, 0.6 x 10 7 / mL, 0.7 x 10 7 / mL, 0.8 x 10 7 / mL, 0.9 x 10 7 / mL, 1.0 x 10 7 / mL, 1.1 x 10 7 / mL, 1.2 x 10 7 / mL, 1.3 x 10 7 / mL, 1.4 x 10 7 / mL, or 1.5 x 10 7 / mL. In a more preferred embodiment, the green algae is added in an amount of 0.8 x 10 7 / mL ~ 1.2 x 10 7 / mL. In a more preferred embodiment, the green algae is added in an amount of 0.9 x 10 71.5 x 10 7 In a specific and preferred embodiment, the green algae is added in an amount of 1 x 10 7 In a specific and preferred embodiment, the green algae is added in an amount of 1 x 10

[0012] In a preferred embodiment, the fermentation culture is carried out under shake culture conditions without additional addition of carbon dioxide. The use of equipment for injecting carbon dioxide into the shake flask is avoided, reducing the cost of carbon dioxide and the equipment for injecting carbon dioxide.

[0013] In a preferred embodiment, the filamentous fungus is first added to the fermentation container containing the fermentation wastewater, and the green algae is added after the observation of the wall-hanging of the mycelium, and the fermentation culture is continued. Further, no additional carbon dioxide is added to the fermentation container.

[0014] In a preferred embodiment, the fermentation culture is carried out for 4 to 10 days. The fermentation culture can be carried out for, for example, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days, or 10 days. In a more preferred embodiment, the fermentation culture is carried out for 5 to 8 days. In a specific and preferred embodiment, the fermentation culture is carried out for 5 days.

[0015] In a preferred embodiment, the separated solid is first freeze-dried, ground into powder, and extracted with an organic solvent to obtain oil. In a more preferred embodiment, the ground powder can be extracted and purified with a chloroform-methanol mixture, and the weight / volume ratio of the powder and the chloroform-methanol mixture is 1: (5-8), more preferably 1: (5.5-6.5). The volume ratio of chloroform and methanol is (1-3): 1. In a more preferred embodiment, the flocculating agent can be aluminum oxide, and the amount of activated carbon added is 1 g to 5 g of activated carbon per 100 mL of supernatant, more preferably 1 g to 2 g of activated carbon per 100 mL of supernatant.

[0016] In a preferred embodiment, the treatment method is specifically implemented as follows:

[0017] Trichoderma harzianum is added to the shake flask containing the fermentation wastewater, and the amount of Trichoderma harzianum added is 0.5 x 10 7 ~1.5 x 10 7 Pre-culture is carried out at a temperature of 25-35°C and a shaking speed of 80-120 rpm;

[0018] After the observation of the wall-hanging of the mycelium in the shake flask, Chlorella or Chlamydomonas is added, and the amount of Chlorella or Chlamydomonas added is 0.5 x 10 7 ~1.5 x 10 7

[0019] ​The fermentation culture is continued for 4-10 days at a temperature of 25-35℃ and a shaking speed of 80-120 rpm, and the light time is alternated for 12 hours light / 12 hours dark.

[0020] In the fermentation culture, no additional carbon dioxide is introduced into the shake flask.

[0021] In a more preferred embodiment, the fermentation broth in the shake flask after the fermentation culture is centrifuged, the solid after the centrifugation is freeze-dried and ground into powder; the powder and the chloroform-methanol mixed solution are mixed at a weight / volume ratio of 1:(5-8), and extraction is performed at a temperature of 25-35℃ and a shaking speed of 80-120 rpm; then centrifugation is performed, and the lower chloroform phase is taken out and spin-dried or air-dried to obtain oil.

[0022] In a more preferred embodiment, aluminum chloride flocculant is added to the supernatant after centrifugation, the supernatant is taken after sedimentation, activated carbon is added in an amount of 1.5 g per 100 mL of supernatant, stirring treatment is performed at 50-60℃, and finally centrifugal treatment is performed to obtain clean water that can be directly discharged into the sewer. Further, the clean water after centrifugal treatment is subjected to quality control by an ultrafiltration membrane through a suction filtration device. Since the water after the final treatment has been subjected to the aforementioned biological treatment, the membrane clogging time is greatly delayed, thereby reducing the loss on the ultrafiltration device. The inventors have not encountered the phenomenon of membrane clogging in many experiments.

[0023] The above scheme is adopted in the present application, and the present application has the following advantages:

[0024] The present application proposes a treatment method for fermentation wastewater, utilizes the symbiotic relationship between filamentous fungi and green algae, uses fermentation wastewater as the principle, and utilizes filamentous fungi and green algae for co-culture, so that the purpose of oil production can be achieved while the fermentation wastewater is treated, and oil such as oleic acid, linoleic acid, and palmitic acid can be extracted from the solid after the treatment of the wastewater, so that part of the cost of treating the fermentation wastewater is offset, thereby reducing the treatment cost of the fermentation wastewater.

[0025] In a further scheme, the waste liquid after the separation of the solid can be changed into clean water meeting the direct discharge into the sewer by simple treatment (such as activated carbon adsorption). BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the present application, the drawings needed in the following embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0027] Figure 1 The photo of the original water sample of the fermentation wastewater used in Example 1.

[0028] Figure 2 The photo of the cell wall of the three shake flasks in Example 1, at this time the green algae has not been added.

[0029] Figure 3 The photo of the fermentation wastewater after biological treatment in the three shake flasks in Example 1.

[0030] Figure 4 The photo of the biomass in the fermentation broth after biological treatment in the three shake flasks in Example 1.

[0031] Figure 5 The photo of the microbial solid residue in Example 1.

[0032] Figure 6 The photo of the oil product in Example 1.

[0033] Figure 7 The photo of the clean water after the final treatment in Example 1.

[0034] Figure 8a The microscope photo of the fermentation broth after biological treatment in Comparative Example 1.

[0035] Figure 8b The microscope photo of the fermentation broth after biological treatment in Example 2. DETAILED DESCRIPTION

[0036] The preferred embodiments of the present application will be described in detail below with reference to the drawings. It should be noted that the description of the embodiments is for the purpose of understanding the present application, and does not constitute a limitation of the present application.

[0037] The present embodiment directly utilizes the fermentation wastewater produced in the fermentation production process (kitchen garbage fermentation treatment) of the company (Suzhou Xinguan Biotechnology Co., Ltd.), and co-cultures the filamentous fungi and the green algae. The solid part in the fermentation broth after biological treatment produces algal oil, and the liquid part after simple treatment can reach the discharge standard and can be directly discharged into the sewer. Further, the inventors found that the Trichoderma harzianum in the filamentous fungi and the green algae (especially Chlorella and Chlamydomonas) have a symbiotic relationship, and the biomass of the two co-cultured fungi and algae significantly increases, and the oil production increases.

[0038] In a specific embodiment, by the filamentous fungus - Trichoderma harzianum, with algae (may be Chlorella, Chlamydomonas) through one-step mixed fermentation, without additional addition of carbon dioxide, shake flask fermentation is carried out for 5 days, and the algae residue produced can produce biomass oil, and the oil quality is provided by the third party institution spectrum test. After biological treatment, the pollution index of the fermentation wastewater is greatly reduced, and then the wastewater can be more easily treated by flocculation and activated carbon adsorption, and then by ultrafiltration to obtain clean water, and the membrane blocking time is greatly delayed.

[0039] In some embodiments, a method for producing oil based on fermentation wastewater is provided, comprising: adding filamentous fungi and green algae to the fermentation wastewater for fermentation culture, then performing solid-liquid separation, and extracting oil from the separated solid. Wherein the filamentous fungi include Trichoderma harzianum, and the green algae include one or more selected from the group consisting of Chlorella vulgaris, Chlamydomonas, Haematococcus pluvialis, Leptolyngbya, Agmenellum and Cladophora, preferably Chlorella and / or Chlamydomonas. The addition amount of the filamentous fungi is 0.5×10 7 ~1.5×10 7 / mL, preferably 0.9×10 7 ~1.2×10 7 / mL. The addition amount of the green algae is 0.5×10 7 ~1.5×10 7 / mL, preferably 0.9×10 7 ~1.2×10 7 / mL. More specifically, the pre-culture inoculation amount is 5% V / V of fungi + 5% V / V of algae.

[0040] Specifically, Trichoderma harzianum is added to a shake flask containing fermentation wastewater, and the addition amount of Trichoderma harzianum is 0.5×10 7 ~1.5×10 7 / mL, and pre-culture is carried out at a temperature of 25~35°C and a shaking speed of 80~120 rpm; after observing that the bacteria in the shake flask are wall-hung, Chlorella or Chlamydomonas is added, and the addition amount is 0.5×10 7 ~1.5×10 7 / mL; the temperature is maintained at 25~35°C and the shaking speed is maintained at 80~120 rpm, and the light time is alternated according to 12 hours light / 12 hours dark, and the fermentation culture is continued for 4~10 days. During the fermentation culture, no additional carbon dioxide is added to the shake flask. The fermentation broth in the shake flask after fermentation culture is centrifuged, the solid after centrifugation is freeze-dried, and is ground into a powder; the powder and chloroform-methanol mixed solution are mixed in a weight / volume ratio of 1:(5~8), and extraction is carried out at a temperature of 25~35°C and a shaking speed of 80~120 rpm; then centrifugation is carried out, and the lower chloroform phase is taken out, and is spin-dried or air-dried to obtain oil.

[0041] In some embodiments, a method for treating fermentation wastewater is provided, comprising: adding filamentous fungi and green algae into fermentation wastewater for fermentation culture, then performing solid-liquid separation, and finally performing centrifugation treatment to obtain clean water that can meet the standard of sewer discharge. The filamentous fungi include Trichoderma harzianum, and the green algae include a combination of one or more selected from Chlorella vulgaris, Chlorella sp., Haematococcus pluvialis, Leptolyngbya sp., Agmenellum quadruplicatum, and Cladophora sp., preferably Chlorella sp. and / or Chlorella sp. The amount of the filamentous fungi added is 0.5 x 10 7 ~1.5 x 10 7 9 x 10 7 2 x 10 7 2 x 10 7 9 x 10 7 2 x 10 7 2 x 10 7 2 x 10

[0042] More specifically, the pre-culture inoculation amount is 5% V / V of fungi + 5% V / V of algae.

[0043] Further, the clean water after centrifugation treatment is subjected to quality control by using an ultrafiltration membrane through a suction filtration device. Since the water after the final treatment has been subjected to the aforementioned biological treatment, the membrane clogging time is greatly delayed, thereby reducing the loss on the ultrafiltration device. The inventors have not observed the phenomenon of membrane clogging in many experiments. Example 1

[0044] The original water sample is fermentation wastewater generated from the fermentation production process of Suzhou Xinguan Biotechnology Co., Ltd., as shown in Figure 1 The pollution data of the original water sample is detected and provided by the Industrial Water Center of Tsinghua Suzhou Environmental Innovation Institute, and the specific data is shown in Table 1 below.

[0045]

[0046] Biological treatment: 3 aliquots of the fermentation wastewater were taken and added to 3 flasks, and the fermentation scale was 500 ml. Trichoderma harzianum (1 x 10 7 Figure 2 7

[0047] Figure 3 Figure 4 The indicators of the water samples after biological treatment in the 3 flasks are shown in Table 2 below. Water sample 1 is the final treated water sample of flask No. 1 (the green algae added is Chlorella), and water samples 2 and 3 are the final treated water samples of flasks No. 2 and No. 3 (the green algae added is Chlamydomonas reinhardtii).

[0048]

[0049] The fermentation broth was centrifuged at 12000 rpm, and the solid and liquid were separated.

[0050] Solid treatment: the separated solid was freeze-dried to obtain microbial solid residue as shown in Figure 5 The freeze-dried material obtained from the above 3 flasks was 3.62 g, 3.76 g and 3.55 g, respectively. Then the freeze-dried material was ground into powder with a grinder, mixed with chloroform-methanol (2:1) mixed solution at a ratio of 1:6 (w / v), and extracted at a reaction kettle temperature of 30°C and a stirring speed of 100 rpm for 1 hour. Then, 5000 rpm centrifugation was performed at room temperature for 10 min, and the lower chloroform phase was taken out, and the upper organic phase was discarded. After spin-drying / blow-drying, the corresponding oil was obtained, which was 0.78 g, 0.86 g and 0.82 g, respectively.

[0051] The appearance of the obtained oil is shown in Figure 6 The oil collected above was detected by a third-party company, Spectrum Lab, and the detection results are shown in Table 3 below.

[0052]

[0053] Among them, butyric acid, hexanoic acid, undecanoic acid, lauric acid, myristic acid, myristoleic acid, pentadecanoic acid, pentadecanoic acid monooleic acid, heptadecanoic acid, heptadecanoic acid monooleic acid, linolenic acid, arachidic acid, etc. were not detected. ​​​​​

[0054] Liquid treatment: the liquid after separation is collected, and 0.1% (w / w) polyaluminum chloride flocculant is added. After settling, the supernatant is adsorbed, and then the supernatant is added to powdered activated carbon 1.5% (W / V) for treatment by a magnetic stirrer, at a temperature of 55 degrees Celsius, for a time of 45 minutes, followed by centrifugation at 12000 rpm, to obtain the following clean water that can be directly discharged into the sewer, as shown in Figure 7

[0055] The detection index of the treated clean water is shown in Table 4 below.

[0056]

[0057] The completely treated clean water meets the direct discharge into the sewer standard.

[0058] Example 2

[0059] Example 2 uses the same treatment method as Example 1, the only difference being that the pH in the shake flask during the fermentation culture process is not controlled, and the microorganism added in the biological treatment is Trichoderma harzianum and Chlorella vulgaris.

[0060] Comparative Example 1

[0061] Comparative Example 1 uses the same treatment method as Example 1, the only difference being that the pH in the shake flask during the fermentation culture process is not controlled, and the microorganism added in the biological treatment is Trichoderma harzianum and Chlorella vulgaris.

[0062] The detection index of the water sample after biological treatment of Example 2 and Comparative Example 1 is shown in Table 5 below.

[0063]

[0064] Figure 8a The microscope photos of the fermentation liquid after biological treatment in Comparative Example 1 are shown in Figure 8b The microscope photos of the fermentation liquid after biological treatment in Example 2 are shown in Figure 8a and Figure 8b Comparing the growth state of different strains and Chlorella vulgaris shown in the above photos, it can be seen that Figure 8b The number of Chlorella vulgaris is obviously more, and therefore the oil production is also higher.

[0065] As shown in the specification and claims, the term "comprising" only indicates the inclusion of the steps and elements explicitly identified, and these steps and elements do not constitute an exclusive list, and the method or device can also include other steps or elements.

[0066] It can be further understood that "multiple" in the present disclosure means two or more, and other quantifiers are similar. ​

[0067] It is further to be understood that the terms "first", "second", etc. are used to describe various information, but the information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other, and do not indicate a particular order or importance. In fact, the expressions "first", "second", etc. can be used interchangeably. For example, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information without departing from the scope of the present disclosure.

[0068] The above embodiments are only to illustrate the technical concept and characteristics of the present application, and are a preferred embodiment, the purpose of which is to enable those skilled in the art to understand the content of the present application and to implement it, and cannot limit the protection scope of the present application.

Claims

1. A method for treating fermentation wastewater, characterized by, The fermentation wastewater is organic wastewater with excessive chemical oxygen demand, total nitrogen, total phosphorus and biochemical oxygen demand index, wherein the biochemical oxygen demand index is greater than 8000 mg / L; the treatment method comprises: adding Trichoderma harzianum into the fermentation wastewater produced after fermentation treatment of kitchen garbage for fermentation culture, until the mycelium wall-hanging phenomenon appears, then adding green algae, the light time is replaced according to 12 hours light / 12 hours dark, and the fermentation culture is carried out for 5-8 days, then solid-liquid separation is carried out, the oil is extracted from the separated solid, the adding amount of the Trichoderma harzianum is 0.5×10 7 ~1.5×10 7 / mL, and the adding amount of the green algae is 0.5×10 7 ~1.5×10 7 / mL. The liquid after the solid-liquid separation is added with a flocculating agent and settled, then powdered activated carbon is added, stirred and treated, centrifuged after the stirring and treatment, and the supernatant of the centrifugation is clean water capable of being directly discharged into a sewer, and the clean water after the centrifugal treatment is subjected to quality control by an ultrafiltration membrane through a suction filtration device; the green algae is Chlorella or Chlamydomonas reinhardtii.

2. The treatment method of fermentation wastewater according to claim 1, characterized by, The fermentation culture is carried out under a shake flask condition without additional addition of carbon dioxide.

3. The treatment method of fermentation wastewater according to claim 1, characterized by, The solid after the solid-liquid separation is first freeze-dried, ground into powder, and then extracted with an organic solvent to obtain oil.

4. The treatment method of fermentation wastewater according to claim 1, characterized by, The treatment method is specifically implemented as follows: The Trichoderma harzianum was added into the shake flask containing the fermentation wastewater, and the amount of the Trichoderma harzianum was 0.5×10 7 ~1.5×10 7 mL, and the pre-culturing was carried out at a temperature of 25~35℃ and a shaking speed of 80~120rpm. After the wall-hanging of the bacterial cells was observed in the shake flask, Chlorella or Chlamydomonas was added in an amount of 0.5 x 10 7 1.5 x 10 7 cells / mL. The temperature is maintained at 25-35℃, the shaking speed is maintained at 80-120 rpm, the light illumination time is alternated according to 12 hours of light / 12 hours of dark, and the fermentation culture is continuously carried out for 5-8 days. In the fermentation culture process, no additional carbon dioxide is added to the shake flask.

5. The method of treating fermentation wastewater according to claim 4, wherein The fermentation liquid in the shake flask after the fermentation culture is centrifuged, the solid after the centrifugation is freeze-dried and ground into powder, the powder is mixed with a chloroform-methanol mixed solution according to a weight / volume ratio of 1:(5-8), and the extraction is carried out at a temperature of 25-35℃ and a shaking speed of 80-120 rpm; then centrifuged, the lower chloroform phase is taken out, and the oil is obtained by spin-drying or air-drying.

6. The method of treating fermentation wastewater according to claim 5, wherein, In the supernatant after the centrifugation of the fermentation liquid, aluminum chloride flocculating agent is added, the supernatant is taken after the settlement, activated carbon is added in an amount of 1.5 g per 100 mL of the supernatant, stirring and treatment are carried out at 50-60℃, and finally centrifugal treatment is carried out, and the clean water capable of being directly discharged into a sewer is obtained after the centrifugal treatment.

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