Fermentation wastewater treatment method and system

Abstract

The invention discloses a fermentation wastewater treatment method and system, and belongs to the field of fermentation wastewater treatment. The problems that in the prior art, zero emission of fermentation wastewater is not achieved, the treatment efficiency is low, and the treatment difficulty is high are solved. Different treatment routes and systems are designed according to different characteristics of high-salt-content wastewater, low-salt-content wastewater and mycoprotein waste liquid, and organic matters and total phosphorus in the high-salt-content wastewater are removed by adopting a grating, coagulating sedimentation, multi-medium filtration and catalytic ozonation process; removing nitrogen and phosphorus from the low-salt wastewater by adopting a high-activity sludge biochemical treatment technology; the mycoprotein waste liquid is fully dehydrated by adopting a sludge collection and volute dehydration technology. The three wastewater treatment processes are carried out at the same time, rear-end effluent circularly enters the three systems to be treated, zero emission of fermentation wastewater is achieved, and the treatment method reduces the wastewater treatment pressure of the systems, improves the treatment efficiency, recycles the wastewater and has wide application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of wastewater treatment, and particularly relates to a method and system for treating fermentation wastewater. Background Art

[0002] With the rapid development of the biological fermentation industry, the discharge of fermentation wastewater has increased sharply. Such wastewater usually has characteristics such as high-concentration organic matter (extremely high COD / BOD 5 value), 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 acidity or salinity. If directly discharged without effective treatment, it will cause water eutrophication, microbial toxicity, and ecological risks.

[0003] At present, there is no process method for treating fermentation industrial wastewater that is highly efficient, has low operating costs, low energy consumption, and saves land. And in most fermentation wastewater treatment processes, due to factors such as large amounts of acid and alkali used resulting in high salt content of the wastewater, large fluctuations in the incoming water, poor biodegradability, and relatively complex components of the pollution components, traditional wastewater treatment processes usually adopt the method of pretreatment plus anaerobic and aerobic to remove substances such as TP (total phosphorus) and total nitrogen in the wastewater and reduce COD (chemical oxygen demand), BOD 5 (biochemical oxygen demand). When the total salt content of the wastewater is relatively high, different strains such as halophilic bacteria can also be used for biochemical treatment. However, as a very small number of microorganisms, halophilic bacteria have a more demanding living environment than other microorganisms, are difficult to culture, and cannot ensure the stability of the system. Conventional biochemical treatment methods often use anaerobic reactors, and biogas is generated during the treatment process, and additional biogas treatment equipment is required, which has certain potential risks. In addition, the existing processes only treat the wastewater, but do not recycle the generated wastewater, do not achieve zero discharge, and the treated wastewater cannot be reused as water resources. Moreover, existing fermentation processes usually divide the generated wastewater into high-salt wastewater, low-salt wastewater, and wastewater containing bacterial residues, and direct mixed treatment has a large impact on the treatment system, and the load borne by the treatment system is high, resulting in difficult treatment and reduced treatment efficiency.

[0004] Therefore, there is an urgent need to find a fermentation wastewater treatment process that can achieve zero discharge of fermentation wastewater, the water quality meets the discharge standards, avoids high loads, reduces the treatment difficulty, meets the treatment requirements of fermentation wastewater, and increases the reuse of fresh water resources. Summary of the Invention

[0005] The present invention provides a method and system for treating fermentation wastewater in view of the above technical problems.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] One of the objectives of the present invention is to provide a method for treating fermented wastewater, and the method is as follows:

[0008] Subject the high-salt wastewater to grid treatment, followed by coagulation and sedimentation, then successively perform filtration and ozone catalytic oxidation. The effluent after the ozone catalytic oxidation process is mixed with the reverse osmosis concentrate of the low-salt wastewater, and is concentrated by disk tube reverse osmosis. The concentrated brine generated by the concentration is evaporated and crystallized to obtain the finished salt, and the fresh water generated by the disk tube reverse osmosis concentration is treated together with the low-salt wastewater;

[0009] While treating the high-salt wastewater, treat the low-salt wastewater. The treatment process is as follows: Subject the low-salt wastewater to grid treatment, then enter the biochemical system, and the effluent successively undergoes filtration, ultrafiltration and reverse osmosis concentration to obtain the reverse osmosis concentrate of the low-salt wastewater and the recycled water. The reverse osmosis concentrate of the low-salt wastewater enters the high-salt wastewater treatment process to be treated together with the high-salt wastewater;

[0010] While treating the high-salt wastewater and the low-salt wastewater, treat the bacterial protein waste liquid. The treatment process is as follows: Concentrate and dehydrate the bacterial protein waste liquid successively, and the filtrate generated by the dehydration enters the high-salt wastewater treatment process to be treated together with the high-salt wastewater.

[0011] Further limit that the influent water quality of the high-salt wastewater is: COD concentration is 11000 - 16500 mg / L, NH 3 -N concentration is 70 - 85 mg / L, TP concentration is 70 - 85 mg / L, TDS concentration is 32100 - 41100 mg / L, pH is 4 - 12; the influent water quality of the low-salt wastewater is: COD concentration is 1100 - 1500 mg / L, BOD 5 concentration is 310 - 380 mg / L, NH 3 -N concentration is 10 - 110 mg / L, TP concentration is 2 - 4 mg / L, TDS concentration is 1500 - 3000 mg / L, pH is 5 - 10.

[0012] Further limit that the effluent water quality discharged after the above treatment method is: COD ≤ 20 mg / L, BOD 5 ≤ 4 mg / L, NH 3 -N ≤ 2 mg / L, TP ≤ 0.5 mg / L, salt content ≤ 500 mg / L, pH is 6 - 9.

[0013] Further limit that 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] Another object of the present invention is to provide a system for the above fermentation wastewater treatment method, which system includes a high-salt wastewater treatment system, a low-salt wastewater treatment system and a microbial protein waste liquid treatment system; the high-salt wastewater treatment system, the low-salt wastewater treatment system and the microbial protein waste liquid treatment system are interconnected through pipelines.

[0015] Further defined, the high-salt wastewater treatment system includes a high-salt wastewater regulating tank, a coagulation and sedimentation integrated device, a 2# multi-media filter, an ozone catalytic oxidation system, a 2# intermediate water tank, a disc tube reverse osmosis device, a disc tube reverse osmosis concentrated water tank and an evaporation crystallizer connected in sequence.

[0016] Further defined, the low-salt wastewater treatment system includes a low-salt wastewater regulating tank, a biochemical system, a 1# intermediate water tank, a 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 connected in sequence.

[0017] Even further defined, the biochemical system is also connected to a backwashing wastewater tank.

[0018] Even further defined, the biochemical system includes a hydrolysis acidification tank, an anoxic tank, an aerobic tank, an MBR membrane tank and a multi-stage circulating biological filler tank.

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

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

[0021] The selection of the wastewater treatment process plays a decisive role in the quality of the effluent. Industrially, fermentation wastewater is usually further divided into high-salt wastewater, low-salt wastewater and wastewater containing bacterial residues. The water quality indexes of high-salt wastewater and low-salt wastewater differ greatly. Direct mixed treatment will increase the treatment pressure of equipment in wastewater treatment and at the same time increase the load on the entire fermentation wastewater treatment system. Therefore, the present invention first treats high-salt wastewater, low-salt wastewater and microbial protein waste liquid simultaneously at the beginning of wastewater treatment, and then circulates and treats them with each other at the back end of the treatment of the three types of wastewater, reducing the load of the wastewater treatment system and improving the treatment efficiency. Compared with the prior art, the present invention also has the following advantages:

[0022] (1) In the present invention, a part of the high-salt wastewater is treated to obtain crystalline salts, and the other part returns to the low-salt wastewater treatment system for treatment to become recycled water. At the same time, the concentrated water generated by reverse osmosis concentration in the low-salt wastewater treatment also enters the high-salt wastewater treatment system for treatment together with the high-salt wastewater. In addition, the filtrate generated in the dehydration process during the treatment of the bacterial protein waste liquid also enters the high-salt wastewater treatment system for treatment, ultimately achieving zero discharge of fermentation wastewater, and greatly reducing the direct mixing treatment cost of high-salt wastewater and low-salt wastewater. It not only reduces the drainage cost, but also reuses the wastewater, and at the same time can produce sodium chloride crystalline salts, having certain economic benefits.

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

[0024] (3) The present invention does not adopt an anaerobic reactor for the treatment of fermentation wastewater, reducing the generation of methane gas and eliminating the need to treat methane gas, greatly improving the safety of the wastewater treatment process.

[0025] (4) In the treatment process of high-salt wastewater, the present invention adopts a pre-membrane treatment process combining a grille, coagulation sedimentation, multi-media filtration and ozone catalytic oxidation. In this pre-membrane treatment process, ozone catalytic oxidation catalyzes and oxidizes macromolecular organic matter to break the chains and open the rings into small-molecule substances, and further mineralizes them into carbon dioxide and water, accelerating the treatment efficiency of the subsequent disk tube reverse osmosis (DTRO) membrane. In the treatment process of high-salt wastewater, the DTRO membrane intercepts metal ions such as sodium ions, chloride ions and a small amount of potassium ions in the wastewater, increasing the wastewater concentration multiple. At the same time, the present invention evaporates and crystallizes the concentrated water generated by the reverse osmosis process of low-salt wastewater and the high-salt concentrated water generated by the DTRO membrane treatment of high-salt wastewater to form sodium chloride crystalline salts, achieving zero discharge of high-salt wastewater.

[0026] (5) In the treatment process of low-salt wastewater, the present invention adopts a combined process of multi-media filtration, ultrafiltration and reverse osmosis, which can not only give full play to the respective functions of the three processes, but also combine them to work synergistically, making the low-salt wastewater reuse rate reach 75%. The remaining 25% enters the high-salt wastewater DTRO equipment for concentration in the form of reverse osmosis concentrated water and is then treated by evaporation and crystallization, achieving zero discharge of low-salt wastewater.

[0027] (6) The TDS concentration in the high-salt wastewater of the present invention is as high as 57000 mg / L, and the pre-membrane treatment process can only remove suspended solids and total phosphorus, and reduce COD and BOD 5For pollutant indicators such as these, there is almost no removal rate for ions in water. Therefore, the combined process of DTRO and evaporation crystallization is adopted in the present invention. After the wastewater is concentrated by DTRO, the concentrated water is obtained. The concentrated water enters the evaporation crystallization equipment for desalination treatment to reduce the burden of the evaporation crystallization process. The fresh water generated by DTRO and the evaporation crystallization condensate enter the low-salt wastewater regulation tank for treatment, and the salt generated by evaporation is reused as industrial salt resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flowchart of the fermentation wastewater treatment method in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following describes the specific embodiments of the present invention in detail in conjunction with the embodiments of the specification. Many specific details are set forth in the following description to fully understand the present invention, but the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0030] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that can be included in at least one implementation manner of the present invention. The "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or selectively exclusive embodiment from other embodiments.

[0031] The experimental methods used in the following embodiments are all conventional methods unless otherwise specified. The materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and those skilled in the art can obtain them through commercial channels without special instructions.

[0032] Example 1

[0033] The high-salt wastewater, low-salt wastewater, and microbial protein waste liquid in this embodiment are fermentation wastewater generated by the biological fermentation of Escherichia coli to synthesize 1, 2, 4-butanetriol. The quality of the high-salt wastewater is: COD is 12890 mg / L, SS (suspended solids) is 83 mg / L, NH 3 -N is 75 mg / L, TP is 75 mg / L, TDS (total dissolved solids) is 32179 mg / L, and pH is 5; the quality of the low-salt wastewater is: COD is 1257 mg / L, BOD 5 is 315 mg / L, NH 3- N is 58 mg / L, TP is 3.1 mg / L, TDS is 2156 mg / L, and pH is 7.8; the spent mycelial protein liquid is the waste liquid of the bacterial residue after filtration of the Escherichia coli bioreactor for synthesizing 1, 2, 4 - butanetriol.

[0034] The fermentation wastewater treatment method is as follows:

[0035] (1) The high - salinity wastewater flows into the high - salinity wastewater adjustment tank. Hydrochloric acid is used to adjust the pH of the wastewater to 4 - 9, and the TDS is 30000 - 40000. In the adjustment tank, a grid is used to intercept floating substances (scum), large - particle pollutants, colloids, etc. in the incoming water. After the wastewater stays for 3 h, a lift pump is used to transport the wastewater in the adjustment tank to the coagulation - sedimentation integrated equipment. Coagulation - sedimentation is carried out using the coagulant aid polyacrylamide (PAM), the coagulants polyaluminum chloride (PAC) and polyferric chloride (PFC) to remove suspended solids and total phosphorus (TP) in the wastewater. The effective residence time is 2 h. Subsequently, it enters the No. 2 multi - media filter to remove impurities such as fine particles and colloidal particles using backwash water. The effluent of the No. 2 multi - media filter enters the ozone catalytic oxidation system. The coupling effect of ozone and the silicon - aluminum - based catalyst (purchased from Guangzhou Bofa Environmental Technology Co., Ltd., SAO3 - I type, specific surface area 220 - 320 m 2 / g) is used to degrade the organic matter in the wastewater, reduce the COD, and prevent the subsequent impact on the treatment efficiency of the DTRO membrane. The effluent and the reverse osmosis concentrate of the low - salinity wastewater enter the No. 2 intermediate water tank for mixing, and are concentrated by the DTRO equipment. The conductivity of the concentrated water generated after the concentration treatment is 70000 - 80000 μm / cm, and the fresh water enters the low - salinity adjustment tank for further reuse treatment. The concentrated water enters the evaporation crystallizer to form the finished sodium chloride salt. There is also an emergency pool in the high - salinity wastewater treatment process. This emergency pool is connected to the high - salinity wastewater adjustment tank to ensure the reliability of the treatment system. It can be used as an accident buffer pool when the influent water quality fluctuates greatly or the evaporation crystallizer fails, ensuring the safety of the system.

[0036] (2) While treating the high - salinity wastewater, the low - salinity wastewater is treated. The low - salinity wastewater flows into the low - salinity wastewater adjustment tank. After the wastewater enters the low - salinity adjustment tank, the residence time is 24 h, the pH is 6 - 9, and the B / C (BOD 5The ratio of BOD to COD is 0.25 - 0.3. First, a grille is used to intercept pollutants such as floating substances (scum), large - particle pollutants, and colloids in the influent water. Then, the wastewater is pumped into the hydrolysis - acidification tank by a lift pump. After a residence time of 8 hours, the COD reduction rate is 30% - 40%, and the B / C is 0.4 - 0.5. Then it enters the anoxic tank. The ORP meter in the anoxic tank is maintained at - 150 mv to + 150 mv, the sludge reflux ratio is 80 - 100%, the reflux time is 0.5 h / d. After a residence time of 10 hours, it flows into the aerobic tank. The DO (dissolved oxygen) in the aerobic tank is maintained at 2 - 4 mg / L. After a residence time of 24 hours, the COD is reduced to below 50 mg / L. The ammonia nitrogen (NH 3 -N) in the effluent is 2 - 3 mg / L, and the TDS is 2000 - 3000. After a residence time of 24 hours, it is sent to the MBR membrane tank by a lift pump. After passing through the MBR membrane, it enters the multi - stage circulating biological packing tank. The hydraulic load of the multi - stage circulating biological packing tank is ≤ 1.5 m 3 / (m 2 ·h). It further removes pollutants such as ammonia nitrogen in the water and reduces COD. The effluent flows into the 1# intermediate water tank by gravity. Then, a lift pump is used to pressurize the wastewater and it passes through the 1# multi - media filter, self - cleaning filter, and ultra - filtration equipment (membrane flux 40 L / m 2 ·h) in sequence to purify fine particulate matters such as suspended solids and colloids in the wastewater, so that the turbidity of the wastewater is ≤ 0.2. The treated water enters the ultra - filtration product water tank. The ultra - filtration product water is transported to the reverse osmosis equipment (membrane flux 13 L / m·h) by a reverse osmosis feed pump for concentration treatment to deeply remove pollutants such as ions, COD, ammonia nitrogen, and TP in the water. After being treated by the reverse osmosis equipment, two parts of water are obtained. One part is recycled water, which can be reused as fresh water resources. The amount of this part of water is 75 wt% of the low - salinity wastewater to be treated. The other part is the remaining 25 wt%. This part of water enters the 2# intermediate water tank and is treated together with the high - salinity wastewater.

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

[0038] The biochemical system in the low - salinity wastewater treatment process mainly includes a hydrolysis - acidification tank, anoxic tank, aerobic tank, MBR membrane tank, and multi - stage circulating biological packing tank. Among them, the hydrolysis - acidification tank mainly removes part of the ammonia nitrogen, total nitrogen, and a very small part of total phosphorus, reduces COD. Its main function is to degrade macromolecular organic matter into small - molecular organic matter and improve the biodegradability of the wastewater. The anoxic tank and aerobic tank remove nitrate nitrogen and a very small part of total phosphorus through the action of nitrifying bacteria, and reduce COD and BOD 5; The MBR membrane tank further removes ammonia nitrogen, total phosphorus and SS, and reduces COD; the multi-stage circulation type biological filler tank removes the remaining ammonia nitrogen and total phosphorus and reduces COD. Among them, the multi-stage circulation type biological filler membrane tank uses a modified honeycomb strong film-hanging biological filler (i.e., irregular polygon porous ceramsite) as the filler of the biological filter bed. It is lighter in texture, higher in cavity rate, and smaller in resistance. This filter material has a larger specific surface area and total pore volume. The porous structure can improve the film-hanging rate, increase the microbial removal efficiency and the ability to resist shock load, has a high anti-mechanical wear strength, an extremely small bed layer resistance, a rough surface, strong chemical stability and a lower density. In the biochemical treatment process of the low-salt wastewater treatment method of this embodiment, the domestication process of the bacteria is as follows: In the sludge domestication stage, the sludge of a wastewater treatment plant similar to the wastewater quality and mixed municipal sludge are selected to enhance the diversity of the bacterial community and put into the biochemical system tank. Nitrogen, phosphorus and other nutrients are added according to BOD 5 : ammonia nitrogen: total phosphorus = 100:5:1 to maintain the metabolic requirements of microorganisms. It is anaerobically shocked in the aerobic tank for 3 days, and then the proportion of industrial wastewater is gradually increased (initially 10% - 20%), and it is increased by 10 - 20% every 3 days until full load. During this period, the changes in the microbial bacterial community are detected by gel electrophoresis, and the water quality and water volume are adjusted. In the initial stage, the DO is maintained at 1 - 2 mg / L, and it is increased to 3 - 4 mg / L in the mature stage. The temperature is controlled at 20 - 30 °C, and the pH is 6.5 - 7.5. When the SV30 (sludge sedimentation ratio) is stable at 20 - 30%, it is gradually refluxed to the anoxic tank and the hydrolysis acidification tank to complete the sludge domestication culture and cultivate salt-tolerant bacteria.

[0039] In the biochemical treatment of this embodiment, a new isolation type exposure technology is adopted. The wastewater from the MBR membrane tank outlet enters the central radiation aeration barrel of the multi-stage circulation type biological filler tank. The wastewater in the central radiation aeration barrel is evenly distributed under the biological bed filler through the aeration disc on the bottom inlet pipeline of the filler tank. The wastewater flows upward in a countercurrent manner through the aeration perforation pipes around the middle radiation aeration barrel and the bottom aeration disc, and the water flows out from the upper water collecting weir at the outlet. While aerating and oxygenating the sewage, this method lifts the sewage upward along the aeration device and then passes through the biological bed to form an internal circulation; through the large circulation dissolved oxygen water flow generated by aeration, its circulation volume and large circulation water flow improve the uniformity of the water flow and the mass transfer efficiency of dissolved oxygen, and prevent the occurrence of air-water short circuit phenomenon caused by channeling formed by directly aerating the filler layer. At the same time, the biological bed used in the biochemical system of the present invention is a high-intensity backwash air flow pulse biological filter bed. This filter bed makes the filler layer in the biological bed in a sub-expanded state (expansion rate about 10%), which improves the disturbance intensity of the filler layer and the scrubbing force between the fillers. The membrane layer (i.e., the filler layer) of the biological bed and the impurities in the bed layer quickly fall off under the strong shearing and collision action, thereby improving the backwashing effect of the biochemical system and avoiding the bonding and blocking of the fillers. The biochemical system adopted in this embodiment has a strong ability to resist shock load, is simple and convenient to operate, has a high treatment efficiency, and the effluent index meets the three-level sewage discharge standard.

[0040] For the pretreatment of high-salt wastewater, a combined pretreatment process of grille + coagulation sedimentation + multi-media filtration + ozone catalytic oxidation is adopted to remove organic matter and total phosphorus from the wastewater while reducing the suspended solid content in the wastewater. After coagulation sedimentation, the suspended solids in the effluent are reduced to less than 50 mg / L, and the total phosphorus is reduced to less than 1 mg / L. After coagulation sedimentation treatment, the COD index of the wastewater is still relatively high, the salt content is about 56,000 mg / L, and the water volume is large. If directly treated by evaporation crystallization, the economic investment and operating cost are relatively high, and the economic benefit is poor. In order to improve the efficiency of evaporation crystallization, the wastewater after coagulation sedimentation still needs to be treated. Since its biodegradability is relatively poor, it is difficult to cultivate microorganisms if a biochemical process is adopted. Therefore, the effluent after coagulation sedimentation is treated by an ozone catalytic oxidation process with rapid reaction, simple operation, safety, and no secondary pollution to remove part of the COD in the water and break the ring and chain of some macromolecular substances in the wastewater into small molecular substances. At the same time, in order to avoid the high suspended solids and colloidal particles in the effluent of coagulation sedimentation caused by the fluctuation of the front-end water quality, a multi-media filter is set at the front end of ozone catalytic oxidation to intercept the suspended solids in the water for the second time, ensure the utilization rate of ozone, and prevent the occurrence of catalyst layer blockage phenomenon.

[0041] In this embodiment, the backwashing in wastewater treatment is realized through the following process: The backwashing of the MBR membrane tank and the multi-stage cyclic biological filler tank in the low-salt wastewater biochemical system is carried out with the water from the 1# intermediate water tank, and its backwashing drainage enters the backwashing wastewater tank and is transported to the low-salt wastewater regulating tank by a submersible sewage pump. The sludge at the bottom of the backwashing wastewater tank is pumped to the sludge thickening tank for further treatment; The 1# multi-media filter, self-cleaning filter and ultrafiltration equipment are backwashed with the water in the ultrafiltration product water tank, and the backwashing drainage goes to the low-salt wastewater regulating tank; The reverse osmosis equipment is backwashed with the water in the reused water tank, and the backwashing drainage goes to the low-salt wastewater regulating tank. The 2# multi-media filter in the high-salt wastewater is backwashed with the water in the ultrafiltration product water tank, and the backwashing water is discharged to the high-salt wastewater regulating tank. All backwashing water comes from within the system, and all backwashing drainage enters the system for re-treatment.

[0042] In this embodiment, the water quality of the fermented wastewater after treatment is shown in Table 1 and Table 2.

[0043] Table 1 Effluent data of each process for high-salt wastewater treatment

[0044]

[0045] Table 2 Effluent data of each process for low-salt wastewater treatment

[0046]

[0047]

[0048] Example 2

[0049] The quality of the high-salt wastewater is as follows: COD is 14,080 mg / L, SS is 83 mg / L, NH 3 -N is 80 mg / L, TP is 80 mg / L, TDS is 39,540 mg / L, and pH is 9; the quality of the low-salt wastewater is as follows: COD is 1,350 mg / L, BOD 5 is 330 mg / L, NH 3 -N is 50 mg / L, TP is 2 mg / L, TDS is 2,680 mg / L, and pH is 8; the bacterial protein waste liquid is the waste liquid of the bacterial residue after filtration of the Escherichia coli bioreactor for synthesizing 1,2,4-butanetriol.

[0050] The difference between this example and Example 1 is as follows: During the treatment of the low-salt wastewater, the wastewater stays in the hydrolysis acidification tank for 10 h, the sludge reflux time in the anoxic tank is 1 h / d, the DO in the aerobic tank is controlled at 5 mg / L, and the hydraulic load of the multi-stage circulating biological filler is ≤ 0.8 m 3 / (m 2 ·h), the ultrafiltration membrane flux in the ultrafiltration equipment is 55 L / m 2 ·h, and the reverse osmosis membrane flux in the reverse osmosis equipment is 20 L / m 2 ·h; during the treatment of the high-salt wastewater, the catalyst used in the ozone catalytic oxidation is an alumina-supported catalyst (purchased from Kele Environmental Engineering Co., Ltd., model OC-KLM, specific surface area ≥ 300 m 2 / g).

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

[0052] Table 3 Effluent data of each process for high-salt wastewater treatment

[0053]

[0054] Table 4 Effluent data of each process for low-salt wastewater treatment

[0055]

[0056]

[0057] Example 3

[0058] The quality of the high-salt wastewater is as follows: COD is 15,580 mg / L, SS is 83 mg / L, NH 3 -N is 81 mg / L, TP is 85 mg / L, TDS is 39,600 mg / L, and pH is 11; the quality of the low-salt wastewater is as follows: COD is 1,550 mg / L, BOD 5 is 345 mg / L, NH 3- The TN is 88 mg / L, the TP is 2.8 mg / L, the TDS is 2980 mg / L, and the pH is 8. The waste liquid of microbial protein is the waste residue liquid after filtration of the bacterial liquid synthesized by Escherichia coli through biological fermentation to produce 1, 2, 4 - butanetriol.

[0059] The difference between this example and Example 1 lies in that during the treatment of low - salinity wastewater, the wastewater stays in the hydrolysis - acidification tank for 12 h, the sludge reflux time in the anoxic tank is 1.2 h / d, the dissolved oxygen is controlled at 4 mg / L, and the hydraulic load of the multi - stage circulating biological filler ≤ 1.5 m 3 / (m 2 ·h), the ultrafiltration membrane flux in the ultrafiltration equipment is 45 L / m 2 ·h, and the reverse osmosis membrane flux in the reverse osmosis equipment is 15 L / m 2 ·h. During the treatment of high - salinity wastewater, the catalyst used in ozone - catalytic oxidation is a manganese - based composite metal catalyst (purchased from Hunan Minsizhuang Technology Co., Ltd., model MINSLITE - B, specific surface area 180 - 240 m 2 / g).

[0060] The water quality of the fermented wastewater after treatment in this example is shown in Table 5 and Table 6.

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

[0062]

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

[0064]

[0065]

[0066] The specific embodiments of the present invention disclosed above are only used to help illustrate the present invention. The specific embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. According to the content of this specification, many modifications and changes can be made. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the relevant technical field can understand and utilize the present invention well.

Claims

1. A method for treating fermentation wastewater, characterized in that: The method is: The high-salinity wastewater is subjected to screen treatment, followed by coagulation and sedimentation, and then filtered and catalytically oxidized by ozone. The effluent after the ozone catalytic oxidation process is mixed with the reverse osmosis concentrate of the low-salinity wastewater, concentrated by disc-tube reverse osmosis, and the concentrated water 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; Low-salt wastewater treatment is carried out while high-salt wastewater treatment is being carried out. The treatment process is as follows: low-salt wastewater is subjected to screen treatment and then enters the biochemical system. The effluent is filtered, ultrafiltered and concentrated by reverse osmosis in sequence. After concentration, low-salt wastewater reverse osmosis concentrate and recycled water are obtained. The low-salt wastewater reverse osmosis concentrate enters the high-salt wastewater treatment process and is treated together with the high-salt wastewater. The bacterial protein waste liquid is treated at the same time as the high-salt wastewater treatment and the low-salt wastewater treatment. The treatment process is: the bacterial protein waste liquid is concentrated and dehydrated in turn, and the filtrate produced by the dehydration enters the high-salt wastewater treatment process and is treated together with the high-salt wastewater.

2. The processing method according to claim 1, characterized in that: The water quality of high-salt wastewater is: COD 11000-16500mg / L, NH3-N 70-85mg / L, TP 70-85mg / L, TDS 32100-41100mg / L, pH 4-12; the water quality of low-salt wastewater is: COD 1100-1500mg / L, BOD5 310-380mg / L, NH3-N 10-110mg / L, TP 2-4mg / L, TDS 1500-3000mg / L, pH 5-10.

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

4. The processing method according to claim 1, characterized in that: 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.

5. A system for the fermentation wastewater treatment method according to any one of claims 1 to 4, the system comprising a low-salt wastewater treatment system, a high-salt wastewater treatment system and a bacterial protein waste liquid treatment system; the low-salt wastewater treatment system, the high-salt wastewater treatment system and the bacterial protein waste liquid treatment system are interconnected by pipelines.

6. The system according to claim 5, characterized in that The low-salt wastewater treatment system includes a low-salt wastewater regulating tank, a biochemical system, a 1# intermediate water tank, a 1# multi-media filter, a self-cleaning filter, an ultrafiltration device, an ultrafiltration water production tank, a reverse osmosis device and a reuse water tank which are connected in sequence.

7. The system according to claim 6, characterized in that The biochemical system is also connected to the backwash wastewater tank.

8. The system according to claim 6, characterized in that Biochemical system The biochemical system includes hydrolysis acidification tank, anoxic tank, aerobic tank, MBR membrane tank and multi-stage circulation biological filler tank.

9. The system according to claim 5, characterized in that The high-salt wastewater treatment system includes a high-salt wastewater regulating tank, a coagulation and sedimentation integrated equipment, a 2# multi-media filter, an ozone catalytic oxidation system, a 2# intermediate water tank, a disc-tube reverse osmosis equipment, a disc-tube reverse osmosis concentrated water tank and an evaporation crystallizer which are connected in sequence.

10. The system according to claim 5, characterized in that The bacterial protein waste liquid treatment system comprises a sludge collection tank, a sludge concentration tank and a screw press dewatering machine which are connected in sequence.

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