A method and system for treating fermentation wastewater

Abstract

This invention discloses a method and system for treating fermentation wastewater, belonging to the field of fermentation wastewater treatment. This invention solves the problems of non-zero discharge, low treatment efficiency, and high treatment difficulty in existing technologies for fermentation wastewater. This invention designs different treatment routes and systems for three types of wastewater with different characteristics: high-salinity wastewater, low-salinity wastewater, and microbial protein waste liquid. For high-salinity wastewater, a process of screen + coagulation sedimentation + multi-media filtration + ozone catalytic oxidation is used to remove organic matter and total phosphorus; for low-salinity wastewater, a highly active sludge biochemical treatment technology is used to remove nitrogen and phosphorus; and for microbial protein waste liquid, a sludge collection + screw press dewatering technology is used to achieve thorough dewatering. The treatment processes for the three types of wastewater are carried out simultaneously, and the effluent is recycled back into the three systems for further treatment, achieving zero discharge of fermentation wastewater. Furthermore, this treatment method reduces the wastewater treatment pressure on the system, improves treatment efficiency, and allows for wastewater reuse, showing broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment, and in particular relates to a method and system for treating fermentation wastewater. Background Technology

[0002] With the rapid development of the bio-fermentation industry, the discharge of fermentation wastewater has increased dramatically. This type of wastewater is typically characterized by high concentrations of organic matter (extremely high COD / BOD5 values), high salt content, high nitrogen and phosphorus content, residual fermentation products (such as organic acids, alcohols, antibiotic precursors, etc.), microbial proteins, and possible fluctuations in pH or salinity. If discharged directly without effective treatment, it will lead to eutrophication of water bodies, microbial toxicity, and ecological risks.

[0003] Currently, there is no efficient, low-cost, energy-saving, and space-saving process for treating fermentation industrial wastewater. Furthermore, most fermentation wastewater treatment processes suffer from high salt content, large fluctuations in influent, poor biodegradability, and complex pollutant composition due to factors such as high acid and alkali usage, traditional wastewater treatment processes typically employ pretreatment combined with anaerobic and aerobic methods to remove TP (total phosphorus) and total nitrogen, and reduce COD (chemical oxygen demand) and BOD5 (biochemical oxygen demand). When the total salt content of the wastewater is high, different bacterial species, such as halophilic bacteria, can be used for biochemical treatment. However, halophilic bacteria are a very small minority of microorganisms, and their living environment is more demanding than other microorganisms, making them difficult to cultivate and ensuring system stability. Conventional biochemical treatment methods often use anaerobic reactors, which produce biogas during the treatment process, requiring additional biogas treatment equipment, which carries certain risks. Furthermore, existing processes only treat wastewater but do not recycle or reuse it, failing to achieve zero discharge. The treated wastewater cannot be reused as a water resource. Moreover, existing fermentation processes typically separate wastewater into high-salinity wastewater, low-salinity wastewater, and wastewater containing bacterial residue. Directly mixing these wastewaters puts a significant impact on the treatment system, increases the load on the system, and makes treatment more difficult, thus reducing treatment efficiency.

[0004] Therefore, there is an urgent need to find a fermentation wastewater treatment process that can achieve zero discharge of fermentation wastewater, meet the discharge standards, avoid high load, reduce treatment difficulty, meet the treatment requirements of fermentation wastewater, and increase the reuse of freshwater resources. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method and system for treating fermentation wastewater.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] One objective of this invention is to provide a method for treating fermentation wastewater, the method being:

[0008] High-salinity wastewater is treated by a screen, followed by coagulation and sedimentation, then filtration and ozone catalytic oxidation. The effluent from the ozone catalytic oxidation process is mixed with low-salinity wastewater reverse osmosis concentrate and concentrated by disc tube reverse osmosis. The concentrate produced by the concentration is evaporated and crystallized to obtain the finished salt. The fresh water produced by the disc tube reverse osmosis concentration is treated together with the low-salinity wastewater.

[0009] While treating high-salinity wastewater, low-salinity wastewater is also treated. The treatment process is as follows: the low-salinity wastewater is treated by a screen and then enters the biological system. The effluent is then filtered, ultrafiltered and concentrated by reverse osmosis in sequence. After concentration, low-salinity wastewater reverse osmosis concentrate and reclaimed water are obtained. The low-salinity wastewater reverse osmosis concentrate is then entered into the high-salinity wastewater treatment process and treated together with the high-salinity wastewater.

[0010] While treating high-salinity wastewater and low-salinity wastewater, bacterial protein waste liquid is also treated. The treatment process is as follows: the bacterial protein waste liquid is concentrated and dehydrated in sequence, and the filtrate produced by dehydration is entered into the high-salinity wastewater treatment process and treated together with the high-salinity wastewater.

[0011] Further specified, the influent water quality for high-salinity wastewater is as follows: COD concentration of 11000–16500 mg / L, NH3-N concentration of 70–85 mg / L, TP concentration of 70–85 mg / L, TDS concentration of 32100–41100 mg / L, and pH of 4–12; the influent water quality for low-salinity wastewater is as follows: COD concentration of 1100–1500 mg / L, BOD5 concentration of 310–380 mg / L, NH3-N concentration of 10–110 mg / L, TP concentration of 2–4 mg / L, TDS concentration of 1500–3000 mg / L, and pH of 5–10.

[0012] Further specified, the effluent quality after treatment by the above method is as follows: COD≤20mg / L, BOD5≤4mg / L, NH3-N≤2mg / L, TP≤0.5mg / L, salinity≤500mg / L, and pH 6~9.

[0013] Further specifying, the catalyst used in the ozone catalytic oxidation process is a silicon-aluminum based catalyst, a carbon-based catalyst, a manganese-based composite metal catalyst, or a ceramic-based catalyst.

[0014] A second objective of this invention is to provide a system for the above-mentioned fermentation wastewater treatment method, the system comprising a high-salinity wastewater treatment system, a low-salinity wastewater treatment system, and a microbial protein waste liquid treatment system; the high-salinity wastewater treatment system, the low-salinity wastewater treatment system, and the microbial protein waste liquid treatment system are interconnected by pipelines.

[0015] Further defining the high-salinity wastewater treatment system, it includes, in sequence, a high-salinity wastewater equalization tank, an integrated coagulation and sedimentation equipment, a No. 2 multi-media filter, an ozone catalytic oxidation system, a No. 2 intermediate water tank, a disc tube reverse osmosis equipment, a disc tube reverse osmosis concentrate tank, and an evaporator crystallizer.

[0016] Further defining the low-salinity wastewater treatment system, it includes, in sequence, a low-salinity wastewater equalization tank, a biochemical system, a No. 1 intermediate water tank, a No. 1 multi-media filter, a self-cleaning filter, an ultrafiltration device, an ultrafiltration product water tank, a reverse osmosis device, and a reclaimed water tank.

[0017] Furthermore, the biochemical system is also connected to the backwash wastewater pool.

[0018] To further define it, the biochemical system includes a hydrolysis acidification tank, an anoxic tank, an aerobic tank, an MBR membrane tank, and a multi-stage circulating biological packing tank.

[0019] Further specifying, the microbial protein waste liquid treatment system includes a sludge collection tank, a sludge thickening tank, and a screw press dewatering machine connected in sequence.

[0020] The beneficial effects of this invention are as follows:

[0021] The choice of wastewater treatment process plays a decisive role in the effluent quality. Industrially, fermentation wastewater is typically further divided into high-salinity wastewater, low-salinity wastewater, and wastewater containing bacterial residue. The water quality indicators of high-salinity and low-salinity wastewater differ significantly. Directly mixing and treating these wastewaters would increase the processing pressure on the equipment and the overall load on the fermentation wastewater treatment system. Therefore, this invention treats high-salinity wastewater, low-salinity wastewater, and bacterial protein waste liquid simultaneously at the beginning of the wastewater treatment process. These three types of wastewater are then circulated back to each other at the end of the treatment process, reducing the load on the wastewater treatment system and improving treatment efficiency. Compared with existing technologies, this invention also has the following advantages:

[0022] (1) In this invention, a portion of the high-salinity wastewater is treated to obtain crystalline salt, while the other portion is returned to the low-salinity wastewater treatment system for further treatment and reuse. Simultaneously, the concentrated water generated during reverse osmosis concentration in the low-salinity wastewater treatment process is then treated together with the high-salinity wastewater in the high-salinity wastewater treatment system. Furthermore, the filtrate generated during the dehydration process of the bacterial protein waste liquid treatment is also treated in the high-salinity wastewater treatment system, ultimately achieving zero discharge of fermentation wastewater. The direct mixing and treatment of high-salinity and low-salinity wastewater significantly reduces costs. This not only reduces drainage costs but also allows for wastewater reuse and the generation of sodium chloride crystalline salt, resulting in certain economic benefits.

[0023] (2) The wastewater treatment process provided by the present invention has low energy consumption, simple operation, easy operation and management, low operating cost, good nitrogen and phosphorus removal effect, high resistance to shock load, and high wastewater reuse rate.

[0024] (3) This invention does not use an anaerobic reactor for the treatment of fermentation wastewater, which reduces the generation of methane gas and eliminates the need to treat the methane gas, thus greatly improving the safety of the wastewater treatment process.

[0025] (4) This invention employs a membrane pretreatment process combining bar screen, coagulation sedimentation, multi-media filtration, and ozone catalytic oxidation in the treatment of high-salinity wastewater. In this process, ozone catalytic oxidation breaks down and opens the rings of large organic molecules, transforming them into smaller molecules that are further mineralized into carbon dioxide and water, thus accelerating the treatment efficiency of the subsequent disc-tube reverse osmosis (DTRO) membrane. During the high-salinity wastewater treatment process, the DTRO membrane retains sodium, chloride, and small amounts of potassium ions and other metal ions in the wastewater, increasing the wastewater concentration ratio. Simultaneously, this invention evaporates and crystallizes the concentrated water produced by the reverse osmosis process of low-salinity wastewater and the high-salinity concentrated water produced by the DTRO membrane treatment of high-salinity wastewater, forming sodium chloride crystals, achieving zero discharge of high-salinity wastewater.

[0026] (5) In the process of treating low salinity wastewater, the present invention adopts a combination of multi-media filtration, ultrafiltration and reverse osmosis, which can give full play to the functions of each of the three processes and combine them to work together, so that the low salinity wastewater reuse rate reaches 75%, and the remaining 25% is concentrated in the form of reverse osmosis concentrate and then treated by evaporation and crystallization to achieve zero discharge of low salinity wastewater.

[0027] (6) The TDS concentration in the high-salt wastewater of this invention is as high as 57,000 mg / L. The membrane pretreatment process can only remove suspended solids and total phosphorus, and reduce pollutant indicators such as COD and BOD5. It has almost no removal rate for ions in the water. Therefore, this invention adopts a combination process of DTRO and evaporation crystallization. The wastewater is concentrated by DTRO to obtain concentrated water. The concentrated water enters the evaporation crystallization equipment for desalination treatment, reducing the burden of the evaporation crystallization process. The fresh water produced by DTRO and the evaporation crystallization condensate enter the low-salt wastewater equalization tank for treatment. The salt produced by evaporation is reused as industrial salt resources. Attached Figure Description

[0028] Figure 1 This is a flowchart of the fermentation wastewater treatment method in Example 1. Detailed Implementation

[0029] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification. Many specific details are set forth in the following description to provide a thorough understanding of the present invention; however, the present invention may also be implemented in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0030] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0031] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0032] Example 1

[0033] In this embodiment, the high-salinity wastewater, low-salinity wastewater, and bacterial protein waste liquid are fermentation wastewater produced by Escherichia coli bio-fermentation to synthesize 1,2,4-butanetriol. The high-salinity wastewater has the following characteristics: COD 12890 mg / L, SS (suspended solids) 83 mg / L, NH3-N 75 mg / L, TP 75 mg / L, TDS (total dissolved solids) 32179 mg / L, and pH 5. The low-salinity wastewater has the following characteristics: COD 1257 mg / L, BOD5 315 mg / L, NH3-N 58 mg / L, TP 3.1 mg / L, TDS 2156 mg / L, and pH 7.8. The bacterial protein waste liquid is the bacterial residue waste liquid after filtration of the bacterial broth from the Escherichia coli bio-fermentation to synthesize 1,2,4-butanetriol.

[0034] The methods for treating fermentation wastewater are as follows:

[0035] (1) High-salinity wastewater flows to a high-salinity wastewater equalization tank. Hydrochloric acid is used to adjust the pH to 4-9 and the TDS to 30,000-40,000. In the equalization tank, a screen is used to intercept floating matter (scum), large particulate pollutants, and colloids in the incoming water. After a 3-hour retention period, the wastewater is pumped to an integrated coagulation and sedimentation system. Coagulation and sedimentation are performed using coagulant aid polyacrylamide (PAM), coagulant polyaluminum chloride (PAC), and polyferric chloride (PFC) to remove suspended solids and total phosphorus (TP) from the wastewater. The effective retention time is 2 hours. The wastewater then enters a No. 2 multi-media filter, where backwash water is used to remove fine particles, colloidal particles, and other impurities. The effluent from the No. 2 multi-media filter enters an ozone catalytic oxidation system, where ozone and a silicon-aluminum based catalyst (purchased from Guangzhou Bofeng Environmental Technology Co., Ltd., type SAO3-I, specific surface area 220-320 m²) are used. 2 The coupling effect of / g) degrades organic matter in the wastewater, reduces COD, and prevents subsequent impact on the treatment efficiency of the DTRO membrane. The effluent and low-salinity wastewater reverse osmosis concentrate enter the No. 2 intermediate water tank for mixing, and then are concentrated by the DTRO equipment. The conductivity of the concentrate after concentration treatment is 70,000-80,000 μm / cm. The desalinated water enters the low-salinity equalization tank for further reuse treatment, and the concentrate enters the evaporator crystallizer to form the finished sodium chloride salt. An emergency tank is also included in the high-salinity wastewater treatment process. This emergency tank is connected to the high-salinity wastewater equalization tank to ensure the reliability of the treatment system. It can serve as an emergency buffer tank in case of large fluctuations in influent water quality or failure of the evaporator crystallizer, ensuring the safety of the system.

[0036] (2) Low-salinity wastewater is treated simultaneously with high-salinity wastewater. The low-salinity wastewater flows to a low-salinity wastewater equalization tank, where it remains for 24 hours. The pH is 6–9, and the B / C ratio (BOD5 to COD) is 0.25–0.3. First, a screen is used to intercept floating matter (scum), large particulate pollutants, colloids, and other pollutants in the incoming water. Then, the wastewater is pumped into a hydrolysis acidification tank. After an 8-hour retention time, the COD reduction rate is 30%–40%, and the B / C ratio is 0.4–0.5. Finally, it enters an anoxic tank. The pH level is maintained between -150mV and +150mV. The sludge return ratio is 80-100%, and the return time is 0.5h / d. After a 10h retention period, the sludge flows into the aerobic tank, where dissolved oxygen (DO) is maintained at 2-4mg / L. After a 24h retention period, the COD drops below 50mg / L. The effluent contains 2-3mg / L of ammonia nitrogen (NH3-N) and 2000-3000 TDS. After a 24h retention period, the effluent is pumped to the MBR membrane tank and then flows through the MBR membrane into the multi-stage circulating biological filler tank. The hydraulic load of the multi-stage circulating biological filler tank is ≤1.5m. 3 / (m 2The process further removes pollutants such as ammonia nitrogen and reduces COD in the water. The effluent flows by gravity into intermediate water tank #1, and then a booster pump pressurizes the wastewater, which then passes it sequentially through multi-media filter #1, self-cleaning filter, and ultrafiltration equipment (membrane flux 40L / m³). 2 The wastewater is purified by treating suspended solids, colloids, and other fine particulate matter to achieve a turbidity of ≤0.2. The treated water then enters the ultrafiltration permeate tank, where it is pumped to the reverse osmosis equipment (membrane flux 13 L / m·h) for concentration. This process deeply removes pollutants such as ions, COD, ammonia nitrogen, and TP from the water. After treatment by the reverse osmosis equipment, two parts of water are obtained. One part is recycled water, which can be reused as freshwater. This part accounts for 75 wt% of the low-salinity wastewater to be treated. The other part, the remaining 25 wt%, enters the No. 2 intermediate water tank for treatment together with the high-salinity wastewater.

[0037] (3) While treating high-salinity wastewater and low-salinity wastewater, the bacterial protein waste liquid is treated. The bacterial protein waste liquid enters the sludge collection tank and is transported to the sludge thickening tank by the sludge transfer pump. After thickening, it is transported to the sludge dewatering system by the sludge transfer pump again and the sludge is dried by the screw press dewatering machine. The filtrate after treatment enters the high-salinity wastewater equalization tank and is treated together with the high-salinity wastewater.

[0038] The biological system in the treatment of low-salinity wastewater mainly includes a hydrolysis acidification tank, an anoxic tank, an aerobic tank, an MBR membrane tank, and a multi-stage circulating biological packing tank. The hydrolysis acidification tank primarily removes some ammonia nitrogen, total nitrogen, and a very small amount of total phosphorus, reducing COD. Its main function is to degrade large organic molecules into smaller ones, improving the biodegradability of the wastewater. The anoxic and aerobic tanks remove nitrate nitrogen and a very small amount of total phosphorus through the action of nitrifying bacteria, reducing COD and BOD5. The MBR membrane tank further removes ammonia nitrogen, total phosphorus, and suspended solids (SS), reducing COD. The multi-stage circulating biological packing tank removes the remaining ammonia nitrogen and total phosphorus, reducing COD. Among them, the multi-stage circulating biological filter bed uses modified honeycomb high-strength biofilm biological packing (i.e., irregular polygonal porous ceramic particles) as the packing material of the biological filter bed. It is lighter, has a higher cavity ratio and lower resistance. The filter material has a larger specific surface area and total pore volume. The porous structure can improve the biofilm attachment rate, increase the microbial removal efficiency and resistance to shock loads, has high resistance to mechanical wear, extremely low bed resistance, rough surface, strong chemical stability and lower density. In the biochemical treatment process of the low-salinity wastewater treatment method in this embodiment, the acclimation process of bacteria is as follows: During the sludge acclimation stage, sludge from wastewater treatment plants and mixed municipal sludge with similar water quality to the wastewater are selected to enhance the diversity of the bacterial community. They are added to the biochemical system tank, and nutrients such as nitrogen and phosphorus are added at a ratio of BOD5: ammonia nitrogen: total phosphorus = 100: 5: 1 to maintain the metabolic needs of microorganisms. The system is then subjected to a three-day aerobic fermentation process, and the proportion of industrial wastewater is gradually increased (initially 10% to 20%), increasing by 10% to 20% every three days until full load is reached. During this period, changes in the bacterial community are detected by gel electrophoresis, and the water quality and quantity are adjusted accordingly. Initially, DO is maintained at 1 to 2 mg / L, and during the maturity period, it is increased to 3 to 4 mg / L. The temperature is controlled at 20 to 30°C, and the pH is 6.5 to 7.5. When the SV30 (sludge settling ratio) stabilizes at 20 to 30%, the sludge is gradually returned to the anoxic tank and the hydrolysis acidification tank to complete the sludge acclimation and cultivation, and salt-tolerant bacteria are cultivated.

[0039] This embodiment employs a novel isolated exposure technology in its biochemical treatment. Wastewater effluent from the MBR membrane tank enters the central radiant aeration tank of a multi-stage circulating biological packing tank. Within the central radiant aeration tank, wastewater is evenly distributed to the lower part of the biological bed packing via aeration discs on the bottom inlet pipe. The wastewater then flows counter-currently upwards through the aeration perforated pipes around the central radiant aeration tank and the bottom aeration discs, ultimately exiting through a gravity-fed collection weir. This method simultaneously aerates and oxygenates the wastewater, lifting it upwards along the aeration device before it passes through the biological bed, forming an internal circulation. The large circulating dissolved oxygen water flow generated by aeration improves the uniformity of the water flow and the mass transfer efficiency of dissolved oxygen, preventing air-water short-circuiting caused by channeling formed by direct aeration of the packing layer. Furthermore, the biological bed used in this invention's biochemical system is a high-intensity backflushing pulsed biological filter bed. This filter bed keeps the packing layer in a sub-expansion state (expansion rate approximately 10%), increasing the disturbance intensity of the packing layer and the scrubbing force between the packing materials. The membrane layer (i.e., the packing layer) and impurities in the biological bed rapidly detach under intense shearing and collision, thereby improving the backwashing effect of the biological system and preventing the packing material from sticking and clogging. The biological system used in this embodiment has strong resistance to shock loads, is simple and convenient to operate, has high treatment efficiency, and the effluent indicators meet the Class III wastewater discharge standards.

[0040] For the pretreatment of high-salinity wastewater, a combined pretreatment process of bar screen + coagulation sedimentation + multi-media filtration + ozone catalytic oxidation is adopted to remove organic matter and total phosphorus from the wastewater while reducing the suspended solids content. After coagulation sedimentation, the suspended solids in the effluent are reduced to below 50 mg / L, and the total phosphorus is reduced to below 1 mg / L. The COD index of the wastewater after coagulation and sedimentation treatment is still relatively high, with a salt content of about 56,000 mg / L and a large volume. Direct evaporation and crystallization treatment would result in high economic input and operating costs and poor economic benefits. In order to improve the efficiency of evaporation and crystallization, the wastewater after coagulation and sedimentation needs to be treated further. Due to its poor biodegradability, it is difficult to cultivate microorganisms using biological processes. Therefore, the effluent after coagulation and sedimentation is treated with ozone catalytic oxidation, which is fast-reacting, simple to operate, safe, and has no secondary pollution. At the same time, it breaks down some of the large molecules in the wastewater into smaller molecules by opening the rings. In order to avoid the high suspended solids and colloidal particles in the coagulation and sedimentation effluent due to fluctuations in the upstream water quality, a multi-media filter is installed at the upstream of the ozone catalytic oxidation to intercept the suspended solids in the water for a second time, ensuring the utilization rate of ozone and preventing the clogging of the catalyst layer.

[0041] In this embodiment, backwashing in wastewater treatment is achieved through the following process: Backwashing of the MBR membrane tank and multi-stage circulating biological packing tank in the low-salinity wastewater biochemical system uses water from the No. 1 intermediate water tank. The backwash water is discharged into the backwash wastewater tank and then pumped to the low-salinity wastewater equalization tank via a submersible pump. The sludge at the bottom of the backwash wastewater tank is pumped to the sludge thickening tank for further treatment. The No. 1 multi-media filter, self-cleaning filter, and ultrafiltration equipment are backwashed using water from the ultrafiltration permeate tank, with the backwash water discharged to the low-salinity wastewater equalization tank. The reverse osmosis equipment is backwashed using water from the recycled water tank, with the backwash water discharged to the low-salinity wastewater equalization tank. In high-salinity wastewater, the No. 2 multi-media filter is backwashed using water from the ultrafiltration permeate tank, with the backwash water discharged to the high-salinity wastewater equalization tank. All backwash water originates from within the system, and all backwash water is reprocessed within the system.

[0042] The water quality of the fermentation wastewater after treatment in this embodiment is shown in Tables 1 and 2.

[0043] Table 1. Effluent data for each stage of high-salinity wastewater treatment

[0044]

[0045] Table 2 Effluent data for each stage of low-salinity wastewater treatment

[0046]

[0047]

[0048] Example 2

[0049] The high-salinity wastewater has the following characteristics: COD 14080 mg / L, SS 83 mg / L, NH3-N 80 mg / L, TP 80 mg / L, TDS 39540 mg / L, and pH 9. The low-salinity wastewater has the following characteristics: COD 1350 mg / L, BOD5 330 mg / L, NH3-N 50 mg / L, TP 2 mg / L, TDS 2680 mg / L, and pH 8. The bacterial protein waste liquid is the bacterial residue waste liquid after filtration of the bacterial liquid synthesized by Escherichia coli through bio-fermentation of 1,2,4-butanetriol.

[0050] The difference between this embodiment and Embodiment 1 is that: in the low-salinity wastewater treatment process, the wastewater remains in the hydrolysis acidification tank for 10 hours, the sludge return time in the anoxic tank is 1 hour / day, the DO in the aerobic tank is controlled at 5 mg / L, and the hydraulic load of the multi-stage circulating biological packing is ≤0.8m. 3 / (m 2 (·h), the ultrafiltration membrane flux in the ultrafiltration equipment is 55 L / m 2 •h, the reverse osmosis membrane flux in the reverse osmosis equipment is 20L / m 2•h; The catalyst used in the ozone catalytic oxidation process for treating high-salinity wastewater is an alumina-supported catalyst (purchased from Kelai Environmental Engineering Co., Ltd., OC-KLM type, specific surface area ≥300 m²). 2 / g).

[0051] The water quality of the fermentation wastewater after treatment in this embodiment is shown in Tables 3 and 4.

[0052] Table 3. Effluent data for each stage of high-salinity wastewater treatment

[0053]

[0054] Table 4. Effluent data for each stage of low-salinity wastewater treatment

[0055]

[0056]

[0057] Example 3

[0058] The high-salinity wastewater has the following characteristics: COD 15580 mg / L, SS 83 mg / L, NH3-N 81 mg / L, TP 85 mg / L, TDS 39600 mg / L, and pH 11. The low-salinity wastewater has the following characteristics: COD 1550 mg / L, BOD5 345 mg / L, NH3-N 88 mg / L, TP 2.8 mg / L, TDS 2980 mg / L, and pH 8. The bacterial protein waste liquid is the bacterial residue waste liquid after filtration of the 1,2,4-butanetriol-synthesized bacterial liquid from Escherichia coli bio-fermentation.

[0059] The difference between this embodiment and Embodiment 1 is that: in the low-salinity wastewater treatment process, the wastewater remains in the hydrolysis acidification tank for 12 hours, the sludge return time in the anoxic tank is 1.2 hours / day, the dissolved oxygen is controlled at 4 mg / L, and the hydraulic load of the multi-stage circulating biological packing is ≤1.5 m³. 3 / (m 2 (·h), the ultrafiltration membrane flux in the ultrafiltration equipment is 45 L / m 2 •h, the reverse osmosis membrane flux in the reverse osmosis equipment is 15L / m 2 •h; The catalyst used for ozone catalytic oxidation in the treatment of high-salinity wastewater is a manganese-based composite metal catalyst (purchased from Hunan Minsilizhuang Technology Co., Ltd., MINSLITE-B type, specific surface area 180-240 m²). 2 / g).

[0060] The water quality of the fermentation wastewater after treatment in this embodiment is shown in Tables 5 and 6.

[0061] Table 5. Effluent data for each stage of high-salinity wastewater treatment.

[0062]

[0063] Table 6. Effluent data for each stage of low-salinity wastewater treatment

[0064]

[0065]

[0066] The specific embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific embodiments described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A method for treating fermentation wastewater, characterized in that, The method is as follows: High-salinity wastewater is treated by a screen, followed by coagulation and sedimentation, then filtration and ozone catalytic oxidation. The effluent from the ozone catalytic oxidation process is mixed with low-salinity wastewater reverse osmosis concentrate and concentrated by disc tube reverse osmosis. The concentrate produced by the concentration is evaporated and crystallized to obtain the finished salt. The fresh water produced by the disc tube reverse osmosis concentration is treated together with the low-salinity wastewater. While treating high-salinity wastewater, low-salinity wastewater is also treated. The treatment process is as follows: the low-salinity wastewater is treated by a screen and then enters the biological system. The effluent is then filtered, ultrafiltered and concentrated by reverse osmosis in sequence. After concentration, low-salinity wastewater reverse osmosis concentrate and reclaimed water are obtained. The low-salinity wastewater reverse osmosis concentrate is then entered into the high-salinity wastewater treatment process and treated together with the high-salinity wastewater. While treating high-salinity wastewater and low-salinity wastewater, bacterial protein waste liquid is also treated. The treatment process is as follows: the bacterial protein waste liquid is concentrated and dehydrated in sequence, and the filtrate produced by dehydration is entered into the high-salinity wastewater treatment process and treated together with the high-salinity wastewater. The influent water quality for high-salinity wastewater is as follows: COD 11000~16500mg / L, NH3-N 70~85mg / L, TP 70-85mg / L, TDS 32100-41100mg / L, pH 4~12; the influent water quality for low-salinity wastewater is as follows: COD 1100~1500mg / L, BOD5 310~380mg / L, NH3-N 10~110mg / L, TP 2~4mg / L, TDS 1500~3000mg / L, pH 5~10.

2. The processing method according to claim 1, characterized in that, The effluent quality after treatment by this method is as follows: COD≤20mg / L, BOD5≤4mg / L, NH3-N≤2mg / L, TP≤0.5mg / L, salinity≤500mg / L, and pH 6~9.

3. The processing method according to claim 1, characterized in that, The catalysts used in the ozone catalytic oxidation process are silicon-aluminum based catalysts, carbon-based catalysts, manganese-based composite metal catalysts, or ceramic-based catalysts.

4. A fermentation wastewater treatment system, characterized in that, The system includes a low-salinity wastewater treatment system, a high-salinity wastewater treatment system, and a microbial protein waste liquid treatment system; the low-salinity wastewater treatment system, the high-salinity wastewater treatment system, and the microbial protein waste liquid treatment system are interconnected through pipelines; The high-salinity wastewater treatment system includes a high-salinity wastewater equalization tank, an integrated coagulation and sedimentation equipment, a No. 2 multi-media filter, an ozone catalytic oxidation system, a No. 2 intermediate water tank, a disc tube reverse osmosis equipment, a disc tube reverse osmosis concentrate tank, and an evaporator crystallizer, connected in sequence. The low-salinity wastewater treatment system includes a low-salinity wastewater equalization tank, a biological system, a No. 1 intermediate water tank, a No. 1 multi-media filter, a self-cleaning filter, an ultrafiltration equipment, an ultrafiltration product water tank, a reverse osmosis equipment, and a reclaimed water tank, which are connected in sequence. The biological system is also connected to the backwash wastewater tank. The biological system includes a hydrolysis acidification tank, an anoxic tank, an aerobic tank, an MBR membrane tank, and a multi-stage circulating biological packing tank. The microbial protein wastewater treatment system includes a sludge collection tank, a sludge thickening tank, and a screw press dewatering machine connected in sequence. High-salinity wastewater flows into a high-salinity wastewater equalization tank for bar screen treatment. After effluent, it enters an integrated coagulation and sedimentation equipment for coagulation and sedimentation. After sedimentation, the effluent enters a No. 2 multi-media filter for further impurity filtration. The effluent then flows through a pipeline into an ozone catalytic oxidation system. After the ozone catalytic oxidation process is completed, the effluent and the low-salinity wastewater reverse osmosis concentrate enter a No. 2 intermediate water tank for mixing. The effluent is then concentrated by a disc tube reverse osmosis equipment. The concentrated water enters a disc tube reverse osmosis concentrate tank and then flows into an evaporator crystallizer for evaporation and crystallization. The fresh water produced by the concentrated water from the disc tube reverse osmosis equipment flows through a pipeline into a low-salinity wastewater equalization tank for treatment together with the low-salinity wastewater. Simultaneously, low-salinity wastewater is treated: Low-salinity wastewater flows to a low-salinity wastewater equalization tank for screen treatment. After effluent, it is pumped into the hydrolysis acidification tank of the biological system via a lift pump. Then, the effluent enters an anoxic tank for further retention, followed by aerobic retention in the aerobic tank. After retention, the effluent is pumped to the MBR membrane tank, and after passing through the MBR membrane, it enters a multi-stage circulating biological packing tank, completing the wastewater treatment within the biological system. During the low-salinity wastewater treatment process, the backwash drainage from the biological system enters the backwash wastewater tank and is then pumped to the low-salinity wastewater treatment system via a submersible pump. The wastewater from the equalization tank and the biological system flows by gravity into the No. 1 intermediate water tank. Then, the wastewater is sent to the No. 1 multi-media filter by a booster pump. The effluent flows into the self-cleaning filter and then into the ultrafiltration equipment for filtration. The filtered effluent enters the ultrafiltration permeate tank. The ultrafiltration permeate is transported to the reverse osmosis equipment for concentration by the reverse osmosis feed water pump. After concentration, low-salinity wastewater reverse osmosis concentrate and reclaimed water are obtained. The low-salinity wastewater reverse osmosis concentrate enters the No. 2 intermediate water tank in the high-salinity wastewater treatment system for treatment together with the high-salinity wastewater. The reclaimed water flows into the reclaimed water tank. While treating high-salinity wastewater and low-salinity wastewater, the bacterial protein waste liquid is also treated: the bacterial protein waste liquid enters the sludge collection tank, and is then transported to the sludge thickening tank by the sludge transfer pump. After thickening, it is transported again by the sludge transfer pump to the screw press dewatering machine for sludge drying. The filtrate after treatment enters the high-salinity wastewater equalization tank and is treated together with the high-salinity wastewater.

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