Ultralow-concentration discharge treatment method and equipment for Maotai-flavor liquor production wastewater

Abstract

The invention discloses an ultra-low emission treatment system and device for Maotai-flavor liquor production wastewater, the wastewater passes through a combination of a rotary mechanical fine grid and a self-cleaning rotary fine grid, and various solids in the wastewater are thoroughly removed; in the pretreatment, precipitation and air floatation are combined, and a phosphorus removal agent, a coagulant and a flocculant are properly added, so that the phosphorus removal burden in the subsequent treatment is reduced. A UASB anaerobic reactor is adopted in the anaerobic treatment section, so that the phenomena of acidification and the like are not easy to occur. The biological treatment adopts an improved two-stage AO treatment process and is combined with an MBR (Membrane Bioreactor), so that the removal effect of COD (Chemical Oxygen Demand) and total nitrogen can be integrally improved, and the suspended solids, COD and total nitrogen concentration in effluent are reduced. In the deep treatment stage, catalytic ozonation and an MBBR biological treatment device are adopted, and a combined process of an efficient sedimentation tank and ultrafiltration / nanofiltration is combined; ozone catalytic oxidation enhances the oxidation capacity of ozone, and improves the B / C ratio and biodegradability of wastewater; mBBR biological treatment has the characteristics of a membrane method and a suspension method, and COD and total nitrogen in the wastewater are further effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment in liquor brewing, and in particular to an ultra-low concentration discharge treatment method and equipment for wastewater produced by Maotai-flavor liquor. Background Art

[0002] Liquor brewing is a traditional process. The production of Maotai-flavor liquor generally uses sorghum as raw material and wheat as high-temperature koji. It is brewed after 2 feedings (adding sand), 9 steamings, 8 fermentations, and 7 wine extractions, which takes 1 year. A large amount of wastewater is generated in the process of liquor production. For every ton of liquor produced, 10-30 tons of wastewater are discharged. The wastewater generated in the production process of Maotai-flavor liquor mainly includes cellar bottom water, pot bottom water, bottle washing water, ground washing water, tank washing water, etc. The wastewater contains raw material residues, lees and other fiber substances. Among them, pot bottom water, cellar bottom water and washing water are high-concentration organic wastewater, and the pollutants are mostly biodegradable organic matter, but their low-carbon alcohol and fatty acid content is relatively large. Maotai-flavor liquor brewing wastewater has the characteristics of high organic matter concentration, high suspended solids concentration, acidity, high chroma, strong odor, etc. It not only has high organic matter concentration (COD value can reach up to 15000-20000mg / L), but also high concentrations of ammonia nitrogen (NH3-N), total nitrogen (TN) and total phosphorus (TP). In addition, the water quality, water volume, water temperature and other indicators fluctuate greatly due to the influence of Maotai-flavor liquor brewing production process, cycle, season and other factors. It is a typical high-concentration organic wastewater. The state and local governments have formulated strict discharge standards for the discharge of liquor brewing wastewater. For example, the "Emission Standards for Water Pollutants in Fermentation Alcohol and Liquor Industry" (GB 27631-2011) stipulates that the water quality of wastewater directly discharged by new factories must reach CODcr≤100mg / L, SS≤50mg / L, NH3-N≤10mg / L, TN≤20mg / L, and TP≤1mg / L. The standard also stipulates special emission limits for certain environmentally sensitive areas, namely CODcr≤50mg / L, SS≤20mg / L, NH3-N≤5mg / L, TN≤15mg / L, TP≤0.5mg / L; some areas are even required to meet the surface water quality standard of Class III, namely CODcr≤20mg / L, BOD5≤4mg / L, NH3-N≤1mg / L, TP≤0.2mg / L.

[0003] The prior art often uses the conventional process of primary pretreatment + secondary biochemical treatment for the wastewater generated at each stage of Maotai-flavor liquor brewing. This process is acceptable for the treatment effect of wastewater with low concentration such as bottle washing and tank washing water, but the treatment effect is poor for wastewater with high chroma and COD concentration such as pot bottom water, cellar bottom water and flushing water. The treated wastewater still contains more organic matter, which is difficult to meet the discharge standard of wastewater. For wastewater with high concentration, it is necessary to add the step of anaerobic treatment after primary pretreatment, and then carry out secondary biochemical treatment represented by AO biochemical treatment process. However, this method has the problems of large sludge production and high reagent consumption. At the same time, the traditional A0 biochemical treatment process is used for biological denitrification. Due to the low denitrification efficiency, the volume of the A0 reaction tank will be too large, and the conventional A0 denitrification system has poor impact resistance. In the fifth to seventh rounds of production wastewater discharged in the brewing process of Maotai-flavor liquor, the concentration of difficult-to-degrade organic matter and organic nitrogen increases, and the proportion of carbon sources that can be used for denitrification by denitrifying bacteria decreases. A large amount of carbon source needs to be added separately, which will further increase the sludge production and operating costs.

[0004] Therefore, in order to meet the water quality requirements for direct discharge, the treatment of Maotai-flavor liquor brewing wastewater generally requires deep treatment. At present, the most widely used deep treatment methods are the following three categories: 1. Fenton, Fenton-like oxidation or iron-carbon micro-electrolysis system with active substance ·0H as the main oxidant. This type of system has good decolorization and purification effects on organic wastewater, but the sludge production is high, and the operation and running costs are relatively high; 2. Ozone, hydrogen peroxide coupled ultraviolet catalysis or heterogeneous catalytic oxidation system. This type of system has a good decolorization effect on colored wastewater, but the mineralization effect on organic pollutants is not thorough enough, and subsequent biochemical treatment is required. The process is long, and after ozone and hydrogen peroxide treatment, the residual oxidant has a strong inhibitory effect on subsequent biochemical treatment; 3. Double membrane treatment system represented by MBR+NF / RO. This type of system produces good water quality, but its essence is still a filtering method, and no substantial mineralization treatment is performed on pollutants in wastewater. At present, most of the wastewater treatment of sauce-flavored liquor adopts a combined process of "pretreatment + anaerobic treatment + main biochemical treatment + deep treatment", but this combined process still has some problems: the anaerobic treatment system often fails to reach the medium temperature condition, and the effluent of the anaerobic system often runs into sludge, causing the loss of anaerobic sludge and resulting in poor removal effect of the anaerobic treatment system; the main biochemical treatment adds a high amount of carbon source, resulting in higher operating costs.

[0005] CN 220485500U provides a treatment system for Maotai-flavor liquor wastewater, including a pretreatment system, an anaerobic treatment system (with a biogas treatment system), a biochemical system and a deep treatment system; the anaerobic system includes an intermediate tank, an anaerobic reactor and a sedimentation tank arranged in sequence, a steam diffuser is installed at the bottom of the intermediate tank, the gas outlet of the anaerobic reactor is connected to the inlet of the biogas treatment system, and the outlet of the biogas treatment system is connected to the steam diffuser; a sludge return pipe is arranged at the bottom of the sedimentation tank, and part of the precipitated sludge is returned to the sludge inlet of the anaerobic reactor through the sludge return pipe. The utility model can ensure the temperature of the anaerobic reactor, and the sludge return pipe is arranged at the bottom of the sedimentation tank, which can increase the sludge concentration and the rising flow rate at the same time, and avoid the loss of sludge in the anaerobic reactor. However, the combination of the biochemical treatment system AAO or multi-stage AO+secondary sedimentation tank of the utility model occupies a relatively large area, and the deep treatment system combines oxidation and biological filter treatment, and no sedimentation tank and filter are arranged, so it is difficult to ensure that the effluent SS meets the standard discharge.

[0006] CN 216336848U discloses an anaerobic treatment device for Maotai-flavor liquor brewing wastewater, comprising a first anaerobic tower and a second anaerobic tower, wherein the first anaerobic tower and the second anaerobic tower are connected in parallel or in series. A first water distributor, a first middle sludge reaction zone, a first lower three-phase separator, a first upper sludge reaction zone and a first upper three-phase separator are sequentially distributed in the first anaerobic tower from bottom to top. The second anaerobic tower has the same structure as the first anaerobic tower. The utility model can select the anaerobic towers to be used in parallel or in series according to the concentration of the wastewater inlet, and the water distributor is set as an umbrella-shaped water distributor, so that wastewater with a high water inlet flow rate can flow out evenly from the gap of the umbrella pieces of the umbrella-shaped water distributor, and the water distribution is uniform and the water distributor is prevented from being blocked. In addition, the anaerobic tower of the utility model forms high and low load zones by setting two three-phase separators, which can effectively enhance the impact load resistance of the anaerobic tower and ensure the stable operation of the anaerobic tower. However, the setting of the middle three-phase separator of this anaerobic tower will lead to poor exhaust of methane gas and hinder the discharge of sludge, affecting the stability of its operation.

[0007] CN 213834834 U provides a deep decolorization and purification system for Maotai-flavor liquor brewing wastewater. The front-end biochemical water produced by Maotai-flavor liquor brewing wastewater is collected through a water collection tank to homogenize the operating load of the deep purification system; most of the organic pollutants, color particles, ammonia nitrogen and possible heavy metals in the wastewater are removed through a primary oxidation reaction tower, and then the residual organic matter and heavy metal pollutants in the wastewater are eliminated through a secondary catalytic oxidation reaction tower, and the residual oxidant in the water produced by the primary oxidation reaction tower is eliminated; the residual SS in the wastewater is removed through a settler to ensure that the produced water is clear and colorless, and all indicators meet the standards. The deep decolorization and purification system provided by the utility model can effectively remove organic pollutants, color-developing particles and heavy metals in Maotai-flavor liquor brewing wastewater, and has the characteristics of simple operation, short process, stable operation, etc., but it relies on secondary chemical oxidation treatment, which inevitably consumes a large amount of oxidant and has high operating costs. At the same time, solid-liquid separation relies only on precipitation and cannot meet the requirements of high-standard emissions.

[0008] CN 216191784U discloses a deep treatment device for Maotai-flavor liquor brewing wastewater, comprising an ozone deep bed catalytic oxidation unit and an aerated biological filter unit. Catalytic fillers are fixed in the oxidation tank of the ozone deep catalytic oxidation unit. The utility model combines the ozone deep bed catalytic oxidation unit with the aerated biological filter unit, and can deeply treat Maotai-flavor liquor brewing wastewater that still does not meet the discharge standard after primary pretreatment and secondary biochemical treatment, so that the effluent meets the discharge standard. However, the use of the biological filter cannot effectively remove suspended solids and cannot meet high-standard discharge requirements.

[0009] CN 114988641 B discloses a method for treating wastewater from the brewing of Maotai-flavor liquor. The pit bottom water, pot bottom water and production water are mixed and sent to a regulating tank to adjust the pH value to 7.5-8, and then enter anaerobic treatment, two-stage aerobic treatment and deep treatment in sequence to achieve standard discharge. The primary and secondary aerobic treatments both use MBBR technology, and the fillers are plastic hollow suspension balls of activated carbon and polyurethane sponge and plastic balls respectively: the deep treatment uses advanced oxidation combined with flocculation treatment. The invention uses a two-stage MBBR process plus advanced oxidation deep treatment, which can improve the impact resistance and load resistance of the wastewater treatment system and the treatment effect of high-concentration brewing wastewater, but the denitrification and phosphorus removal effects are difficult to meet the requirements of high emission standards. .

[0010] CN 113620538 B discloses a high-concentration pit bottom wastewater treatment process for sauce-flavor liquor, including a high-concentration lime milk reaction tank, pH adjustment, filter press filtration, primary biochemical treatment (AAO, secondary sedimentation tank), primary lime milk coagulation reaction, the first and third sedimentation tanks, ozone catalytic oxidation, secondary biochemical reaction (AAO + sedimentation tank), secondary lime flocculent coagulation reaction, the second and third sedimentation tanks, precision filter filtration, and standard discharge. However, the system uses lime in many places, resulting in an increase in the pH of the reaction. After each addition of lime, acid needs to be added for pH adjustment, so that the salt content in the wastewater will increase. In addition, the use of multi-stage sedimentation tanks will inevitably occupy a large area.

[0011] At present, the treatment method for direct discharge of Maotai-flavor liquor brewing wastewater generally adopts the process of pretreatment + anaerobic treatment + secondary biochemical treatment (generally nitrogen removal and phosphorus removal) + deep treatment, but this combined process still has some problems: the anaerobic treatment system often fails to reach the medium temperature condition, and the anaerobic system effluent sludge phenomenon is relatively common, causing the loss of anaerobic sludge, resulting in reduced removal effect of the anaerobic treatment system; the main biochemical treatment has a high carbon source addition, resulting in high operating costs. The process used in the deep treatment system is relatively mixed, and the final filtration step is often ignored. The phosphorus removal effect generally does not meet the direct discharge or higher treatment requirements.

[0012] In practical applications, an optimized treatment system for liquor brewing wastewater is needed that is easy to operate, has low operating costs, and is reliable in operation, so as to overcome the shortcomings of the existing technology and achieve direct discharge and ultra-low emission of wastewater. Summary of the invention

[0013] The purpose of the present invention is to provide an ultra-low concentration discharge treatment method and equipment for Maotai-flavor liquor production wastewater, in which the water quality of the treated wastewater reaches the water quality standard of Class III surface water and can be directly discharged or reused.

[0014] In order to achieve the above object, the present invention adopts the following technical solutions:

[0015] A method for treating wastewater from the production of Maotai-flavor liquor at an ultra-low concentration, which is used to treat wastewater from brewing liquor, comprises the following steps:

[0016] Step S1: Preprocessing stage

[0017] Step S11: After various wastewaters generated during the liquor brewing process are collected, they first enter the rotary mechanical fine screen through the water inlet pipe to filter larger solid particles in the wastewater;

[0018] Step S12: The wastewater then enters two self-cleaning rotary fine screens arranged in series to filter out solids with smaller particles in the wastewater;

[0019] Step S13: Entering the regulating tank again to adjust the water quality and water quantity;

[0020] Step S14: the wastewater enters the primary sedimentation tank through a lifting pump, a dephosphorizing agent is added to the primary sedimentation tank (), and the phosphate radicals in the wastewater react with the added dephosphorizing agent to form phosphate precipitates, thereby being mostly removed, and the precipitated sludge is sent to the sludge treatment system for concentration, dehydration and drying;

[0021] Step S15: The supernatant liquid from the primary sedimentation tank then enters the flotation tank, where coagulants and flocculants are added. The colloidal solids in the clear liquid react with the added coagulants and flocculants to form flocs, which float up and are removed together with the light substances in the wastewater under the action of tiny bubbles in the flotation tank. The scum in the flotation tank is sent to the sludge treatment system for concentration, dehydration and drying.

[0022] Step S2: Anaerobic treatment stage

[0023] Step S21: the flotation clear liquid after the flotation tank treatment enters the upflow UASB anaerobic reactor for anaerobic methane production. In the UASB anaerobic reactor, the flotation tank clear liquid passes through the anaerobic reaction zone and the gas-liquid-solid three-phase separation zone respectively. The organic matter in the clear liquid produces methane gas under the action of anaerobic microorganisms in the anaerobic reaction zone. The methane gas is separated from the liquid phase in the three-phase separation zone and enters the biogas storage tank from the gas connecting pipe at the top for storage. Then, it is sent to the biogas user as fuel gas through the biogas pipeline, or sent to the biogas burner for combustion, thereby eliminating the harm of methane gas to the environment.

[0024] Step S22: The liquid from the gas-liquid-solid separation zone enters the anaerobic sludge sedimentation tank through the connecting pipe for further solid-liquid separation. The obtained precipitated sludge is partially sent back to the UASB anaerobic reactor for utilization through the sludge pump, and part of it is sent to the sludge treatment system as residual sludge for concentration, dehydration and drying. The obtained precipitated clear liquid enters the improved secondary biochemical treatment section for further treatment;

[0025] Step S3: Secondary biochemical treatment stage

[0026] Step S31: In the secondary biochemical treatment section, the precipitated clear liquid first enters the first-stage anoxic tank for denitrification treatment. The denitrifying bacteria in the first-stage anoxic tank use the residual low-level fatty acids, ethanol and other organic matter in the wastewater to reduce the nitrate and nitrite ions that flow back into the wastewater into nitrogen gas, thereby achieving the effect of denitrification and denitrification.

[0027] Step S32: The effluent from the first-stage anoxic tank then enters the first-stage aerobic tank to oxidize the remaining ammonia nitrogen in the wastewater into nitrate and nitrite to achieve nitrification; wherein part of the mixed liquid in the first-stage aerobic tank is refluxed to the first-stage anoxic tank;

[0028] Step S33: the effluent from the first-stage aerobic pool enters the second-stage anoxic pool, and the denitrifying bacteria in the second-stage anoxic pool use the residual organic matter in the effluent from the anaerobic sludge sedimentation pool flowing through the anaerobic reaction surpassing pipe to reduce the remaining nitrate into nitrogen gas;

[0029] Step S34: The effluent from the second-stage anoxic tank then enters the second-stage aerobic tank, where the remaining organic matter and ammonia nitrogen in the wastewater are further utilized by aerobic microorganisms under the aerobic conditions of the second-stage aerobic tank;

[0030] Step S35: Subsequently, the effluent from the second-stage aerobic pool enters the MBR membrane separation pool for concentration and separation. The suspended solids and microorganisms in the wastewater are retained by the MBR membrane and remain in the MBR membrane separation pool to become the concentrated liquid in the MBR membrane separation pool. The clear liquid that passes through the MBR membrane becomes the produced water and enters the subsequent treatment unit for further treatment.

[0031] Part of the concentrated liquid from the MBR membrane separation tank is returned to the first-stage aerobic tank as return sludge, and enters the second-stage anoxic tank with the water flow to achieve denitrification. Another part of the concentrated liquid from the MBR membrane separation tank is sent to the sludge treatment system as residual sludge for concentration, dehydration and drying.

[0032] Step S4: Advanced oxidation treatment stage

[0033] Step S41: the produced water of the MBR membrane separation tank then enters the ozone catalytic oxidation tank for oxidation treatment. The ozone catalytic oxidation tank is connected to the ozone generator. Under the action of the catalyst, the ozone is decomposed to generate hydroxyl free radicals ·OH with stronger oxidation effect, thereby oxidizing and decomposing the difficult biodegradable organic matter in the wastewater to generate organic matter that is easily decomposed and utilized by microorganisms;

[0034] Step S5: Post-biological treatment stage

[0035] Step S51: The effluent from the ozone catalytic oxidation tank then passes through a moving bed bioreactor and a high-efficiency sedimentation tank in sequence. MBBR biological fillers are placed in the moving bed bioreactor. The surface of the fillers is easy to fix microbial membranes, so the surface of the fillers has both anoxic and aerobic zones, so that the remaining ammonia nitrogen and nitrate nitrogen in the wastewater are further removed by nitrification and denitrification;

[0036] The clear liquid enters the high-efficiency sedimentation tank, where coagulants and flocculants are added. The suspended and colloidal solids remaining in the influent form flocs with larger particles and easy precipitation under the action of coagulants and flocculants, which are then precipitated and removed. The precipitated sludge produced in the high-efficiency sedimentation tank is sent to the sludge treatment system for concentration, dehydration and drying.

[0037] Step S6: Nanofiltration treatment stage

[0038] Step S61: The clear liquid after being treated in the high-efficiency sedimentation tank enters the immersed ultrafilter for filtration. The liquid that passes through the ultrafiltration membrane becomes clear liquid through a vacuum suction pump, while the remaining bacteria and suspended particles are retained on the surface of the ultrafiltration membrane as filter membranes. The sludge trapped on the surface of the ultrafiltration membrane is removed and discharged through backwashing or washing;

[0039] Step S62: the ultrafiltration effluent enters the nanofiltration filter for further processing to obtain a higher quality filtered clear liquid;

[0040] Step S63: The nanofiltration effluent enters the disinfection pool, where disinfectant is added for disinfection treatment, and then is pumped to various reuse water points for reuse or direct discharge through a reuse water pump;

[0041] The concentrated water produced by nanofiltration is returned to the ozone catalytic oxidation tank for further oxidation treatment;

[0042] When the effluent water quality of ultrafiltration meets the requirements, the ultrafiltration effluent can be directly discharged into the disinfection tank through surpassing nanofiltration.

[0043] Preferably, in step S1, the pretreatment stage includes a rotary mechanical fine screen, a second self-cleaning rotary fine screen, a regulating tank, a primary sedimentation tank and a flotation tank;

[0044] The rotary mechanical fine screen adopts a rake tooth mechanical structure, the gap width of which is mm, and is used to remove larger particles, including husks and debris;

[0045] The two self-cleaning rotary fine screens are both of a drum structure, with a screen gap of 0.mm, which is used to remove fine solids, including solids in husks, wine lees and sorghum seeds;

[0046] The primary sedimentation tank adopts a conventional sedimentation tank, and a reaction zone is set in the primary sedimentation tank. A dephosphorizing agent is added in the reaction zone, and the dephosphorizing agent can generate phosphate precipitate with phosphate radicals;

[0047] The flotation tank adopts a conventional flotation tank, in which a reaction zone is set, and a coagulant and a flocculant are added to the reaction zone.

[0048] The sludge after treatment in the primary sedimentation tank and the scum after treatment in the flotation tank are sent to the sludge treatment system for concentration, dehydration and drying.

[0049] Preferably, the dephosphorizing agent comprises one of ferric salt, ferrous salt or aluminum salt composed of sulfuric acid or hydrochloric acid;

[0050] The coagulant is polyferric sulfate PFS, polyaluminium chloride PAC, or other iron-based or aluminium-based coagulants, and the flocculant is polyacrylamide PAM.

[0051] Preferably, in step S2, the anaerobic treatment stage includes an upflow UASB anaerobic reactor, a biogas storage tank, a biogas burner and an anaerobic sludge sedimentation tank;

[0052] The UASB anaerobic reactor is provided with an anaerobic reaction zone and a gas-liquid-solid three-phase separation zone, and the top of the UASB anaerobic reactor is connected to a biogas storage tank and a biogas burner;

[0053] Part of the sludge in the anaerobic sludge sedimentation tank is returned to the water inlet area of ​​the UASB anaerobic reactor, and part of it is sent to the sludge treatment system as residual sludge for concentration, dehydration and drying;

[0054] Wastewater enters from the bottom of the UASB anaerobic reactor and flows upward, driving the anaerobic sludge into a suspended state. The sludge with gas is lighter and floats faster, and the sludge becomes heavier after the gas is released and sinks. This can form an internal circulation of the sludge and play a mixing role.

[0055] In the anaerobic treatment stage of step S2, organic matter in the wastewater generates methane gas under the action of anaerobic microorganisms in the anaerobic reaction zone, and the methane gas is separated from the liquid phase as a gas phase in the three-phase separation zone and enters the biogas storage tank for storage;

[0056] The biogas stored in the biogas storage tank is sent to biogas users through a biogas pipeline or burned by a biogas burner to eliminate the harm of methane gas to the environment and generate heat energy for utilization;

[0057] The liquid from the gas-liquid-solid separation zone leaves the UASB anaerobic reactor through a connecting pipe and enters the anaerobic sludge sedimentation tank for further solid-liquid separation. The anaerobic sludge carried out in the separation liquid is then pumped back to the UASB anaerobic reactor for utilization, and the clear precipitated liquid enters the next treatment system for further treatment.

[0058] Preferably, the biogas storage tank adopts a water-sealed tank to ensure the pressure inside the biogas tank is stable.

[0059] Preferably, the heat energy generated by the combustion of the biogas is transferred to the reaction liquid in the anaerobic reaction zone through a heat exchanger provided in the UASB anaerobic reactor, so as to increase the temperature of the sludge reaction liquid.

[0060] Preferably, in step S3, the secondary AO treatment system used in the secondary biochemical treatment stage includes a first-stage anoxic tank, a first-stage aerobic tank, a second-stage anoxic tank, a second-stage aerobic tank and an MBR membrane separation tank;

[0061] An internal reflux is arranged between the first-stage anoxic tank and the first-stage aerobic tank, and the internal reflux adopts a treatment flow rate of times to return the nitrified liquid in the first-stage aerobic tank to the first-stage anoxic tank for denitrification;

[0062] In order to ensure the effect of denitrification and TN compliance, a portion of the effluent from the anaerobic sludge sedimentation tank bypasses the first-stage anoxic tank and the first-stage aerobic tank and directly enters the second-stage anoxic tank to supplement the denitrification carbon source of the second-stage anoxic tank;

[0063] The MBR membrane separation tank is provided with an MBR membrane, and the MBR membrane adopts a special microfiltration membrane for retaining sludge or microorganisms in the MBR membrane separation tank;

[0064] Part of the mixed liquid in the MBR separation tank is returned to the first-stage aerobic tank as return sludge, and the other part is sent to the sludge treatment system as residual sludge for concentration, dehydration and drying; the filtered clear liquid of the MBR membrane is sent to the next-stage treatment system as the treated liquid for further treatment.

[0065] Preferably, in step S4, the advanced oxidation treatment stage includes an ozone catalytic oxidation tank and an ozone generator, and the ozone catalytic oxidation tank is connected to the ozone generator;

[0066] The internal catalyst bed of the ozone catalytic oxidation tank is filled with a non-supported ozone oxidation catalyst. Under the action of the catalyst, ozone is decomposed to generate hydroxyl free radicals ·OH (E 0 =2.8V), oxidatively decompose the difficult-to-biodegrade organic matter in the wastewater to generate easily biodegradable organic matter;

[0067] The non-supported ozone oxidation catalyst comprises a silicon-aluminum-based material combined with a catalytic metal. A circulation system is provided in the ozone catalytic oxidation tank to prevent the catalyst bed from being blocked. The flow rate of the circulating liquid is 50-100% of the treatment flow rate.

[0068] The circulating backwashing arrangement of the ozone catalytic oxidation tank increases the speed at which wastewater passes through the catalyst bed and prevents the catalyst bed from being blocked.

[0069] Preferably, in step S5, the post-biological treatment stage includes a moving bed bioreactor and a high-efficiency sedimentation tank;

[0070] MBBR biological filler is placed in the moving bed bioreactor. The MBBR filler is made of PE material, generally has a diameter of 2.5 cm, a density of nearly 1, and is placed in the reaction tank with a volume of about 40%;

[0071] The surface of the MBBR biological filler is easy to fix the microbial film, so the filler surface has both anoxic and aerobic zones, thereby improving the denitrification effect of the moving bed bioreactor;

[0072] Coagulant and flocculant are added into the high-efficiency sedimentation tank, and the sedimentation sludge produced by the high-efficiency sedimentation tank is sent to the sludge treatment system for concentration, dehydration and drying.

[0073] Preferably, in step S6, the nanofiltration treatment stage includes an immersed ultrafilter, a nanofilter and a disinfection tank;

[0074] The membrane pore size of the ultrafiltration component used in the submerged ultrafilter is 0.01-0.1 microns, which is used to ensure that bacteria and suspended particles are filtered out. The ultrafiltration component is submerged and uses a vacuum pump to suck out water;

[0075] The nanofiltration is used as a safeguard to obtain a higher quality filtered clear liquid; the concentrated water produced by the nanofiltration is returned to the ozone catalytic oxidation tank for further oxidation treatment; the nanofiltration effluent enters the disinfection tank, and after the disinfection agent is added to the disinfection tank for disinfection treatment, it is then sent to each reuse water use point through a reuse water pump for reuse or direct discharge.

[0076] Compared with the prior art, the present invention has the following beneficial effects:

[0077] (1) The present invention adopts a rotary mechanical fine screen and two self-cleaning rotary fine screens to grade the filter gaps from wide to fine, which can continuously, effectively and thoroughly remove a large amount of solids such as husks and lees remaining in the liquor brewing wastewater, and implement continuous and automatic operation.

[0078] (2) The combination of sedimentation and flotation is used in the pretreatment stage of the present invention, and appropriate addition of phosphorus removal agents and coagulants and flocculants can reduce the burden of phosphorus removal in subsequent treatments and improve the efficiency of phosphorus removal. At the same time, it can also more efficiently remove suspended solids in wastewater and reduce the organic load of subsequent treatment stages.

[0079] (3) The present invention adopts UASB anaerobic reactor in the anaerobic treatment stage, and sets anaerobic reaction zone and three-phase separation zone inside. Compared with anaerobic reactors such as CSTR, it has the advantages of high sludge concentration, high reaction efficiency, good contact effect between organic matter and sludge, good reaction stability, and not easy to acidify, and has good adaptability to the concentration change of brewing wastewater. An anaerobic sedimentation tank is set behind UASB to make up for the deficiency of sludge running easily in the three-phase separation zone of UASB due to the influence of methane gas production, and better realize the separation of anaerobic sludge, and the separated anaerobic sludge is returned to the entrance of UASB to enter the reaction zone for sludge replenishment and recycling.

[0080] (4) The biological treatment after the anaerobic treatment stage of the present invention adopts an improved secondary AO treatment process and combines MBR. The first-stage AO is provided with internal recirculation, and no intermediate sedimentation tank is provided after the first-stage AO. The second-stage AO is not provided with internal circulation, and the effluent of the anaerobic treatment partially transcends to the second-stage anoxic reaction tank to supplement the denitrification carbon source of the second-stage anoxic tank. This can improve the removal effect of COD and total nitrogen as a whole, and reduce the concentrations of suspended solids, COD and total nitrogen in the effluent. Considering that the total nitrogen entering the second-stage AO system is relatively low, the second-stage AO is not provided with internal circulation, which can reduce the volume of the second-stage AO tank body, and save floor space and construction costs while meeting the treatment requirements. The use of MBR for solid-liquid concentration and separation can maintain a higher sludge concentration in the secondary AO system, improve the treatment effect, and further save floor space.

[0081] (4) The present invention adopts ozone catalytic oxidation plus MBBR biological treatment device in the deep treatment stage, combined with a high-efficiency sedimentation tank and ultrafiltration / nanofiltration combined process. Ozone catalytic oxidation not only enhances the oxidizing capacity of ozone and effectively improves the B / C ratio biodegradability of wastewater, but also does not increase the salinity of the effluent. MBBR biological treatment has the characteristics of both membrane and suspension methods, not only has a high sludge concentration, but also has a good denitrification effect, which can further reduce the COD and total nitrogen in the wastewater. The setting of a high-efficiency sedimentation tank and the addition of coagulants and flocculants can effectively reduce the suspended solids in the biochemical effluent and further remove total phosphorus; the configuration of ultrafiltration and nanofiltration further reduces the submicron and nanometer solid content in the effluent and further improves the effluent water quality.

[0082] In summary, the present invention provides a practical and reliable treatment system for the water quality characteristics of liquor brewing wastewater, such as high solids, high concentration, difficulty in degradation, high ammonia nitrogen, high phosphorus, large and unstable water quality changes. The treated water quality can meet the water quality standards of Class III surface water and meet the requirements of direct discharge or reuse. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 A schematic process flow diagram of an ultra-low concentration discharge treatment method for Maotai-flavor liquor production wastewater provided in an embodiment of the present invention.

[0084] The serial numbers in the figure are as follows:

[0085] 1-1, rotary mechanical fine screen; 1-2, self-cleaning rotary fine screen; 1-3, regulating tank; 1-4, primary sedimentation tank; 1-5, flotation tank; 2-1, UASB anaerobic reactor; 2-2, biogas storage tank; 2-3, biogas burner; 2-4, anaerobic sludge sedimentation tank; 3-1, first-stage anoxic tank; 3-2, first-stage aerobic tank; 3-3, second-stage anoxic tank; 3-4, second-stage aerobic tank; 3-5, MBR membrane separation tank; 4-1, ozone catalytic oxidation tank; 4-2, ozone generator; 5-1, moving bed bioreactor; 5-2, high-efficiency sedimentation tank; 6-1, submerged ultrafilter; 6-2, nanofiltration filter; 6-3, disinfection tank; 7, sludge treatment system. DETAILED DESCRIPTION

[0086] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0087] like Figure 1 As shown, an ultra-low concentration discharge treatment method for Maotai-flavor liquor production wastewater disclosed in the present invention includes pretreatment, anaerobic treatment, improved secondary biochemical treatment, advanced oxidation treatment, post-biological treatment section, nanofiltration and the like, so as to achieve effluent water quality reaching Class III surface water water quality standards.

[0088] Among them, a method for treating wastewater from the production of Maotai-flavor liquor at an ultra-low concentration is used to treat wastewater from brewing liquor, and comprises the following steps:

[0089] Step S1: Preprocessing stage

[0090] Step S11: After being collected, various wastewaters generated during the liquor brewing process first enter the rotary mechanical fine screen 1-1 through the water inlet pipe to filter larger particles of solids such as husks and debris in the wastewater.

[0091] Step S12: Then the wastewater enters into two self-cleaning rotary fine screens 1-2 arranged in series in sequence, which are used to filter out solids such as husks, distiller's grains, sorghum seeds and other smaller particles in the wastewater.

[0092] Step S13: Enter the regulating tank 1-3 again to adjust the water quality and water quantity.

[0093] Step S14: entering the primary sedimentation tank 1-4 through a lifting pump, adding a dephosphorization agent into the primary sedimentation tank 1-4, the dephosphorization agent including one of iron salt, ferrous salt or aluminum salt composed of sulfuric acid or hydrochloric acid.

[0094] The phosphate radicals in the wastewater react with the added dephosphorizing agent to form phosphate precipitates, thereby being mostly removed, and the precipitated sludge is sent to the sludge treatment system 7 for concentration, dehydration and drying.

[0095] Step S15: The supernatant from the primary sedimentation tank then enters the flotation tank 1-5, in which coagulants and flocculants are added, and the colloidal solids in the clear liquid react with the added coagulants and flocculants to form flocs, which, together with the light substances in the wastewater, float up and are removed under the action of tiny bubbles in the flotation tank 1-5, and the scum in the flotation tank 1-5 is sent to the sludge treatment system 7 for concentration, dehydration and drying.

[0096] Step S2: Anaerobic treatment stage

[0097] Step S21: The flotation clear liquid after treatment in the flotation tank 1-5 enters the UASB anaerobic reactor 2-1 for anaerobic methane production. In the UASB anaerobic reactor 2-1, the flotation clear liquid passes through the anaerobic reaction zone and the gas-liquid-solid three-phase separation zone respectively. The organic matter in the clear liquid produces methane gas in the anaerobic reaction zone under the action of anaerobic microorganisms. The methane gas is separated from the liquid phase in the three-phase separation zone and enters the biogas storage tank 2-2 for storage from the gas connecting pipe at the top. Then, it is sent to the biogas user for use as fuel gas through the biogas pipeline, or sent to the biogas burner 2-3 for combustion, thereby eliminating the harm of methane gas to the environment.

[0098] Step S22: The liquid coming out of the gas-liquid-solid separation zone enters the anaerobic sludge sedimentation tank 2-4 through the connecting pipe for further solid-liquid separation. The obtained precipitated sludge is partially sent back to the UASB anaerobic reactor 2-1 through the sludge pump for utilization, and part of it is sent to the sludge treatment system 7 as residual sludge for concentration, dehydration and drying. The obtained precipitated clear liquid enters the improved secondary biochemical treatment section for further treatment.

[0099] Step S3: Secondary biochemical treatment stage

[0100] Step S31: In the secondary biochemical treatment section, the precipitated clear liquid first enters the first-stage anoxic tank 3-1 for denitrification treatment. The denitrifying bacteria in the first-stage anoxic tank 3-1 use the residual low-level fatty acids, ethanol and other organic matter in the wastewater to reduce the nitrate and nitrite ions that flow back into the wastewater into nitrogen gas, thereby playing a role in denitrification and denitrification.

[0101] Step S32: The effluent from the first-stage anoxic tank 3-1 then enters the first-stage aerobic tank 3-2 to oxidize the remaining ammonia nitrogen in the wastewater into nitrate and nitrite to achieve nitrification. Part of the mixed liquid from the first-stage aerobic tank is refluxed to the first-stage anoxic tank 3-1.

[0102] Step S33: the effluent from the first-stage aerobic pool 3-2 enters the second-stage anoxic pool 3-3, and the denitrifying bacteria in the second-stage anoxic pool 3-3 use the anaerobic reaction to reduce the remaining nitrates into nitrogen gas by using the residual low-level fatty acids, ethanol and other organic substances in the effluent from the anaerobic sludge sedimentation pool 2-4 flowing through the pipe.

[0103] Step S34: Subsequently, the effluent from the second-stage anoxic tank 3-3 enters the second-stage aerobic tank 3-4, and the remaining organic matter and ammonia nitrogen in the wastewater are further utilized by aerobic microorganisms under the aerobic conditions of the second-stage aerobic tank 3-4.

[0104] Step S35: Subsequently, the effluent from the second-stage aerobic tank 3-4 enters the MBR membrane separation tank 3-5 for concentration and separation. The suspended solids and microorganisms in the wastewater are retained by the MBR membrane and retained in the MBR membrane separation tank 3-5 to become the concentrated liquid in the MBR membrane separation tank. The clear liquid that passes through the MBR membrane becomes the produced water and enters the subsequent treatment unit for further treatment.

[0105] Part of the concentrated liquid from the MBR membrane separation tank is returned to the first-stage aerobic tank 3-2 as return sludge, and enters the second-stage anoxic tank 3-4 with the water flow to achieve denitrification, and another part of the concentrated liquid from the MBR membrane separation tank is sent to the sludge treatment system 7 as residual sludge for concentration, dehydration and drying.

[0106] Step S4: Advanced oxidation treatment stage

[0107] Step S41: The produced water of the MBR membrane separation tank 3-5 then enters the ozone catalytic oxidation tank 4-1 for oxidation treatment. The ozone catalytic oxidation tank 4-1 is connected to the ozone generator 4-2. Under the action of the catalyst, the ozone is decomposed to generate hydroxyl free radicals ·OH with stronger oxidizing effect, thereby oxidizing and decomposing the difficult-to-biodegrade organic matter in the wastewater to generate organic matter that is easily decomposed and utilized by microorganisms.

[0108] Step S5: Post-biological treatment stage

[0109] Step S51: The effluent from the ozone catalytic oxidation tank 4-1 then passes through the moving bed bioreactor 5-1 and the high-efficiency sedimentation tank 5-2 in sequence. MBBR biological fillers are placed in the moving bed bioreactor 5-1. The surface of the fillers is easy to fix microbial film, so the surface of the fillers has both anoxic zones and aerobic zones, so that the remaining ammonia nitrogen and nitrate nitrogen in the wastewater can be further removed by nitrification and denitrification.

[0110] The clear liquid enters the high-efficiency sedimentation tank 5-2, in which coagulants and flocculants are added. The suspended and colloidal solids remaining in the influent form flocs with larger particles and easy precipitation under the action of the coagulants and flocculants, which are then precipitated and removed. The precipitated sludge produced in the high-efficiency sedimentation tank 5-2 is sent to the sludge treatment system 7 for concentration, dehydration and drying.

[0111] Step S6: Nanofiltration treatment stage

[0112] Step S61: The clear liquid after being treated in the high-efficiency sedimentation tank 5-2 enters the immersed ultrafilter 6-1 for filtration. The liquid passing through the ultrafiltration membrane becomes clear liquid through a vacuum suction pump, while the remaining bacteria and suspended particles are retained on the surface of the ultrafiltration membrane as filter membranes. The sludge trapped on the surface of the ultrafiltration membrane is removed and discharged by backwashing or cleaning.

[0113] Step S62: The ultrafiltration effluent enters the nanofiltration filter 6-2 for further processing to obtain a higher quality filtered clear liquid.

[0114] Step S63: The nanofiltration effluent enters the disinfection tank 6-3, and after disinfectant is added to the disinfection tank 6-3 for disinfection treatment, it is sent to various reuse water use points through a reuse water pump for reuse or direct discharge.

[0115] The concentrated water produced by nanofiltration is returned to the ozone catalytic oxidation tank 4-1 for further oxidation treatment.

[0116] When the effluent water quality of ultrafiltration meets the requirements, the ultrafiltration effluent can be directly discharged into the disinfection tank through surpassing nanofiltration.

[0117] The present invention provides a set of ultra-low concentration discharge treatment equipment for Maotai-flavor liquor production wastewater according to the above process. In step S1, the pretreatment stage includes a rotary mechanical fine screen 1-1, two self-cleaning rotary fine screens 1-2, a regulating tank 1-3, a primary sedimentation tank 1-4 and a flotation tank 1-5.

[0118] The rotary mechanical fine screen 1-1 adopts a rake tooth mechanical structure with a gap width of 1-5 mm, which is used to remove larger particles, including husks and debris.

[0119] The second self-cleaning rotary fine screen 1-2 both adopts a drum structure, and the screen gap is 0.2-1mm, which is used to remove fine solids, including solids in husks, wine lees and sorghum.

[0120] The primary sedimentation tank 1-4 adopts the form of a conventional sedimentation tank. A reaction zone is set in the primary sedimentation tank 1-4. A dephosphorizing agent is added in the reaction zone. The dephosphorizing agent can generate phosphate precipitates with phosphate radicals.

[0121] The flotation tanks 1-5 are conventional flotation tanks, in which a reaction zone is set, and coagulants and flocculants are added to the reaction zone.

[0122] The sludge treated in the primary sedimentation tanks 1-4 and the scum treated in the flotation tanks 1-5 are sent to the sludge treatment system 7 for concentration, dehydration and drying.

[0123] In step S2, the anaerobic treatment stage includes a UASB anaerobic reactor 2-1, a biogas storage tank 2-2, a biogas burner 2-3 and an anaerobic sludge sedimentation tank 2-4.

[0124] An anaerobic reaction zone and a gas-liquid-solid three-phase separation zone are provided in the UASB anaerobic reactor 2-1. The top of the UASB anaerobic reactor 2-1 is connected to a biogas storage tank 2-2 and a biogas burner 2-3.

[0125] Part of the sludge in the anaerobic sludge sedimentation tank 2-4 is returned to the water inlet area of ​​the UASB anaerobic reactor 2-1, and part of it is sent to the sludge treatment system 7 as residual sludge for concentration, dehydration and drying.

[0126] Wastewater enters from the bottom of the UASB anaerobic reactor 2-1 and flows upward, driving the anaerobic sludge into a suspended state. The gas-carrying sludge is lighter and floats faster, and the sludge becomes heavier after the gas is released and sinks. This can form an internal circulation of the sludge and play a mixing role.

[0127] In the anaerobic treatment stage of step S2, organic matter in the wastewater produces methane gas under the action of anaerobic microorganisms in the anaerobic reaction zone. The methane gas is separated from the liquid phase as a gas phase in the three-phase separation zone and enters the biogas storage tank 2-2 for storage.

[0128] The biogas stored in the biogas storage tank 2-2 is sent to the biogas user through the biogas pipeline or burned by the biogas burner 2-3, thereby eliminating the harm of methane gas to the environment and generating heat energy for utilization.

[0129] The liquid from the gas-liquid-solid separation zone leaves the UASB anaerobic reactor 2-1 through the connecting pipe and enters the anaerobic sludge sedimentation tank 2-4 for further solid-liquid separation. The anaerobic sludge brought out by the separation liquid is then pumped back to the UASB anaerobic reactor 2-1 for utilization, and the clear precipitated liquid enters the next treatment system for further treatment.

[0130] Furthermore, in this embodiment, the biogas storage tank adopts a water seal tank to ensure the pressure inside the biogas tank is stable.

[0131] Furthermore, in this embodiment, when necessary, such as in northern regions or cold seasons, the heat energy generated by the biogas combustion can be transferred to the reaction liquid in the anaerobic reaction zone through a heat exchanger provided in the UASB anaerobic reactor 2-1 to increase the temperature of the sludge reaction liquid.

[0132] In step S3, the secondary AO treatment system used in the secondary biochemical treatment stage includes a first-stage anoxic tank 3-1, a first-stage aerobic tank 3-2, a second-stage anoxic tank 3-3, a second-stage aerobic tank 3-4 and an MBR membrane separation tank 3-5.

[0133] An internal recirculation is set between the first-stage anoxic pool 3-1 and the first-stage aerobic pool 3-2. The internal recirculation adopts 5 times the treatment flow rate to return the nitrified liquid of the first-stage aerobic pool to the first-stage anoxic pool for denitrification.

[0134] In order to ensure the effect of denitrification and TN compliance, a portion of the effluent from the anaerobic sludge sedimentation tank bypasses the first-stage anoxic tank 3-1 and the first-stage aerobic tank 3-2 and directly enters the second-stage anoxic tank 3-3 to supplement the denitrification carbon source of the second-stage anoxic tank 3-4.

[0135] An MBR membrane is arranged in the MBR membrane separation tank 3-5. The MBR membrane adopts a special microfiltration membrane to intercept sludge or microorganisms in the MBR membrane separation tank 3-5.

[0136] Part of the mixed liquid in the MBR separation tank 3-5 is returned to the first-stage aerobic tank 3-2 as return sludge, and the other part is sent to the sludge treatment system 7 as residual sludge for concentration, dehydration and drying. The filtered clear liquid of the MBR membrane is sent to the next-stage treatment system as the treated liquid for further treatment.

[0137] In step S4, the advanced oxidation treatment stage includes an ozone catalytic oxidation tank 4-1 and an ozone generator 4-2, and the ozone catalytic oxidation tank 4-1 is connected to the ozone generator 4-2.

[0138] The internal catalyst bed of the ozone catalytic oxidation tank 4-1 is filled with a non-supported ozone oxidation catalyst. Under the action of the catalyst, ozone will be decomposed to generate hydroxyl free radicals ·OH (E 0 =2.8V), oxidatively decompose the difficult-to-biodegrade organic matter in the wastewater to generate easily biodegradable organic matter.

[0139] The non-supported ozone oxidation catalyst includes a silicon-aluminum-based material combined with a catalytic metal. A circulation system is arranged in the ozone catalytic oxidation tank 4-1 to prevent the catalyst bed from being blocked. The flow rate of the circulating liquid is 50-100% of the processing flow rate.

[0140] The circulating backwash setting of the ozone catalytic oxidation tank increases the speed of wastewater passing through the catalyst bed and prevents the catalyst bed from being blocked.

[0141] In step S5, the post-biological treatment stage includes a moving bed bioreactor 5-1 and a high-efficiency sedimentation tank 5-2.

[0142] MBBR biological filler is placed in the moving bed bioreactor 5-1. The MBBR filler is made of PE material, has a diameter of 2.5 cm, and a density close to 1. It accounts for about 40% of the volume in the reaction tank.

[0143] The surface of the MBBR filler is easy to fix the microbial film, so the filler surface has both anoxic and aerobic zones, thereby improving the denitrification effect of the moving bed bioreactor 5-1.

[0144] Coagulants and flocculants are added to the high-efficiency sedimentation tank 4-2, and the precipitated sludge produced by the high-efficiency sedimentation tank 4-2 is sent to the sludge treatment system 7 for concentration, dehydration and drying.

[0145] In step S6, the nanofiltration treatment stage includes an immersed ultrafilter 6-1, a nanofilter 6-2 and a disinfection tank 6-3.

[0146] The membrane pore size of the ultrafiltration component used in the immersed ultrafilter 6-1 is 0.01-0.1 microns, which is used to ensure that bacteria and suspended particles are filtered out. The ultrafiltration component is immersed and uses a vacuum pump to suck out water.

[0147] Nanofiltration 6-2 is used as a safeguard to obtain a higher quality filtered clear liquid. The concentrated water produced by nanofiltration is returned to the ozone catalytic oxidation tank 4-1 for further oxidation treatment. The nanofiltration effluent enters the disinfection tank 6-3, where disinfectant is added for disinfection treatment, and then is sent to each reuse water point through a reuse water pump for reuse or direct discharge.

[0148] Furthermore, in this embodiment, the coagulant is polyferric sulfate PFS, polyaluminium chloride PAC, or other iron-based or aluminium-based coagulants, and the flocculant is polyacrylamide PAM.

[0149] The following is a detailed description in conjunction with specific implementation parameters.

[0150] A certain Maotai-flavor liquor brewing enterprise generates production wastewater and domestic sewage from its affiliated living facilities during the brewing process, totaling 6000m 3 / d.

[0151] After various types of wastewater are collected, they first enter the rotary mechanical fine screen through the water inlet pipe to filter out larger particles of husks, debris and other solids in the wastewater; then they enter the two self-cleaning rotary fine screens arranged in series in turn to filter out smaller particles of husks, wine lees, sorghum and other solids in the wastewater; then they enter the regulating tank for water quality and water quantity adjustment; then they enter the primary sedimentation tank through the lifting pump, and the phosphate in the influent of the primary sedimentation tank reacts with the added phosphorus removal agent to form phosphate precipitates, which are mostly removed, and the precipitated sludge is sent to the sludge treatment system for concentration, dehydration and drying; the supernatant of the primary sedimentation tank then enters the flotation tank, and the colloidal solids in the supernatant of the flotation tank react with the added coagulant and flocculant to form floccules, and together with the light substances in the wastewater, they float up and are removed under the action of tiny bubbles in the flotation tank; the scum in the flotation tank is sent to the sludge treatment system for concentration, dehydration and drying; The clear liquid from the flotation tank enters the UASB anaerobic reactor for anaerobic methane production. In the UASB anaerobic reactor, the clear liquid from the flotation tank passes through the anaerobic reaction zone and the gas-liquid-solid three-phase separation zone respectively. The organic matter in the clear liquid produces methane gas under the action of anaerobic microorganisms in the anaerobic reaction zone. The methane gas is separated from the liquid phase in the three-phase separation zone and enters the biogas storage tank from the gas connecting pipe at the top for storage. It is then sent to biogas users through the biogas pipeline for use as fuel gas, or sent to the biogas burner for combustion, eliminating the harm of methane gas to the environment. The liquid coming out of the gas-liquid-solid separation zone enters the anaerobic sludge sedimentation tank through the connecting pipe for further solid-liquid separation. The obtained precipitated sludge is partially sent back to the UASB anaerobic reactor for utilization by a sludge pump, and part is sent to the sludge treatment system as residual sludge for concentration, dehydration and drying. The obtained precipitated clear liquid enters the improved secondary biochemical treatment section for further treatment.

[0152] In the improved secondary biochemical treatment section, the precipitated clear liquid first enters the first-stage anoxic tank for denitrification reaction, where the denitrifying bacteria use the residual low-level fatty acids, ethanol and other organic matter in the wastewater to reduce the nitrate and nitrite ions that flow back from the inside into nitrogen gas, thereby playing the role of denitrification and denitrification; then the wastewater enters the first-stage aerobic tank, so that the remaining ammonia nitrogen in the wastewater is oxidized into nitrate and nitrite, and nitrification is achieved; part of the mixed liquid in the first-stage aerobic tank flows back to the first-stage anoxic tank; then, the effluent from the first-stage aerobic tank enters the second-stage anoxic tank, where the reaction Nitrifying bacteria use the residual low-level fatty acids, ethanol and other organic matter in the effluent of the anaerobic sedimentation tank flowing through the anaerobic reaction pipe to reduce the remaining nitrate into nitrogen gas; then the wastewater enters the second-stage aerobic tank, and the remaining organic matter and ammonia nitrogen in the wastewater are further used by aerobic microorganisms under aerobic conditions; then, the effluent of the second-stage aerobic tank enters the MBR membrane separation tank for concentration and separation, and the suspended solids and microorganisms in the wastewater are intercepted and retained in the MBR membrane separation tank by the MBR membrane, and the clear liquid that passes through the MBR membrane becomes produced water and enters the subsequent treatment unit for further treatment. Part of the concentrated liquid in the MBR membrane separation tank is returned to the first-stage aerobic tank as return sludge, and enters the second-stage anoxic tank with the water flow to achieve denitrification, and part of the concentrated liquid in the MBR membrane separation tank is sent to the sludge treatment system as residual sludge for concentration, dehydration and drying.

[0153] The produced water from the MBR pool then enters the ozone catalytic oxidation pool for oxidation treatment. Under the action of the catalyst, ozone is decomposed to generate hydroxyl free radicals ·OH with stronger oxidation effect, thereby oxidizing and decomposing the difficult biodegradable organic matter in the wastewater to generate organic matter that is easy for microorganisms to decompose and utilize; the circulating backwash setting of the ozone catalytic oxidation pool increases the speed of the wastewater passing through the catalyst bed and prevents the catalyst bed from being blocked. The effluent from the ozone catalytic oxidation pool then passes through the moving bed bioreactor (MBBR) and the high-efficiency sedimentation tank in turn, and the clear liquid enters the subsequent ultrafiltration and nanofiltration filtration system for further treatment. MBBR biological fillers are placed in the MBBR, and the surface of the fillers is easy to fix microbial film, so the surface of the fillers has both anoxic and aerobic zones, so that the remaining ammonia nitrogen and nitrate nitrogen in the wastewater can be further removed by nitrification and denitrification. The suspended and colloidal solids remaining in the influent of the high-efficiency sedimentation tank are formed into flocs with larger particles and easy precipitation under the action of the addition of coagulant PAC and flocculant PAM, and are precipitated and removed. The precipitated sludge produced in the high-efficiency sedimentation tank is sent to the sludge treatment system for concentration, dehydration and drying.

[0154] The clear liquid from the high-efficiency sedimentation tank then enters the immersed ultrafilter for filtration. Through the vacuum suction pump, the liquid that passes through the ultrafiltration membrane becomes clear liquid, while the remaining bacteria and suspended particles are present on the surface of the ultrafiltration membrane as filter membranes. The sludge trapped on the surface of the ultrafiltration membrane is removed and discharged through backwashing or cleaning. The ultrafiltration effluent enters the nanofiltration filter for further treatment to obtain a higher quality filtered clear liquid; the nanofiltration effluent enters the disinfection tank, where disinfectants are added for disinfection treatment, and then is sent to each reuse water point through a reuse water pump for reuse or direct discharge. The concentrated water produced by the nanofiltration is returned to the ozone catalytic oxidation tank for further oxidation treatment.

[0155] Through the above wastewater treatment process, COD, BOD5, NH3-N, TN, TP and chromaticity in liquor brewing wastewater are effectively treated, and the water quality of the effluent from the disinfection pool meets the standard of Class III surface water.

[0156] Table 1 Water quality of inlet and outlet water in this embodiment

[0157]

[0158]

[0159] The present invention adopts a combination of precipitation and flotation in pretreatment, and appropriately adds phosphorus removal agent, coagulant and flocculant, which can reduce the burden of phosphorus removal in subsequent treatment and improve the removal efficiency of phosphorus. The UASB reactor is used in the anaerobic treatment section, which has the advantages of high sludge concentration, high reaction efficiency, good contact effect between organic matter and sludge, good reaction stability, not prone to acidification and other phenomena, and good adaptability to concentration changes of brewing wastewater. The biological treatment adopts an improved two-stage AO treatment process and combines MBR. The first stage AO is equipped with internal reflux, and no intermediate sedimentation tank is set after the first stage AO. The effluent of the anaerobic sedimentation tank is partially surpassed to the second stage anoxic reaction tank to supplement its denitrification carbon source, which can improve the removal effect of COD and total nitrogen as a whole and reduce the suspended solids and COD and total nitrogen concentrations in the effluent. In the deep treatment stage, ozone catalytic oxidation plus MBBR biological treatment equipment is used, combined with a high-efficiency sedimentation tank and ultrafiltration / nanofiltration combined process; ozone catalytic oxidation not only enhances the oxidation capacity of ozone, effectively improves the B / C ratio and biodegradability of wastewater, but also does not increase the salinity of the effluent; MBBR biological treatment has the characteristics of both membrane and suspension methods, not only has a high sludge concentration, but also has a good denitrification effect, which can further effectively reduce the COD and total nitrogen in the wastewater.

[0160] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0161] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0162] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for treating wastewater from the production of Maotai-flavor liquor at ultra-low concentration, which is used to treat wastewater from brewing liquor, characterized in that: The steps include: Step S1: Preprocessing stage Step S11: After various wastewaters generated during the liquor brewing process are collected, they first enter the rotary mechanical fine screen (1-1) through the water inlet pipe to filter larger solid particles in the wastewater; Step S12: Then the wastewater enters two self-cleaning rotary fine screens (1-2) arranged in series to filter out solids with smaller particles in the wastewater; Step S13: Enter the regulating tank (1-3) to adjust the water quality and water quantity; Step S14: the wastewater enters the primary sedimentation tank (1-4) through a lifting pump, a dephosphorizing agent is added to the primary sedimentation tank (1-4), the phosphate radicals in the wastewater react with the added dephosphorizing agent to form phosphate precipitates, and thus most of the phosphate radicals are removed, and the precipitated sludge is sent to the sludge treatment system (7) for concentration, dehydration and drying; Step S15: the supernatant liquid from the primary sedimentation tank then enters the flotation tank (1-5), a coagulant and a flocculant are added to the flotation tank (1-5), the colloidal solids in the clear liquid react with the added coagulant and flocculant to form flocs, and together with the light substances in the wastewater, they float up and are removed under the action of tiny bubbles in the flotation tank (1-5), and the scum in the flotation tank (1-5) is sent to the sludge treatment system (7) for concentration, dehydration and drying; Step S2: Anaerobic treatment stage Step S21: The flotation clear liquid after treatment in the flotation tank (1-5) enters the upflow UASB anaerobic reactor (2-1) for anaerobic methane production. In the UASB anaerobic reactor (2-1), the flotation clear liquid passes through the anaerobic reaction zone and the gas-liquid-solid three-phase separation zone respectively. The organic matter in the clear liquid produces methane gas in the anaerobic reaction zone under the action of anaerobic microorganisms. The methane gas is separated from the liquid phase in the three-phase separation zone and enters the biogas storage tank (2-2) for storage through the gas connecting pipe at the top. Then, it is sent to the biogas user for use as fuel gas through the biogas pipeline, or sent to the biogas burner (2-3) for combustion, thereby eliminating the harm of methane gas to the environment; Step S22: The liquid from the gas-liquid-solid separation zone enters the anaerobic sludge sedimentation tank (2-4) through the connecting pipe for further solid-liquid separation. The obtained sedimentation sludge is partially sent back to the UASB anaerobic reactor (2-1) for utilization through the sludge pump, and part of it is sent to the sludge treatment system (7) as residual sludge for concentration, dehydration and drying. The obtained sedimentation clear liquid enters the improved secondary biochemical treatment section for further treatment; Step S3: Secondary biochemical treatment stage Step S31: In the secondary biochemical treatment section, the precipitated clear liquid first enters the first-stage anoxic tank (3-1) for denitrification treatment. The denitrifying bacteria in the first-stage anoxic tank (3-1) use the residual low-level fatty acids, ethanol and other organic matter in the wastewater to reduce the nitrate and nitrite ions that flow back into the wastewater into nitrogen gas, thereby achieving the effect of denitrification and denitrification. Step S32: The effluent from the first-stage anoxic tank (3-1) then enters the first-stage aerobic tank (3-2) to oxidize the remaining ammonia nitrogen in the wastewater into nitrate and nitrite to achieve nitrification; wherein part of the mixed liquid from the first-stage aerobic tank is refluxed into the first-stage anoxic tank (3-1); Step S33: the effluent from the first-stage aerobic tank (3-2) enters the second-stage anoxic tank (3-3), and the denitrifying bacteria in the second-stage anoxic tank (3-3) use the residual organic matter in the effluent from the anaerobic sludge sedimentation tank (2-4) flowing through the anaerobic reaction pipe to reduce the remaining nitrate into nitrogen gas; Step S34: The effluent from the second-stage anoxic tank (3-3) then enters the second-stage aerobic tank (3-4), where the remaining organic matter and ammonia nitrogen in the wastewater are further utilized by aerobic microorganisms under the aerobic conditions of the second-stage aerobic tank (3-4); Step S35: Subsequently, the effluent from the second-stage aerobic tank (3-4) enters the MBR membrane separation tank (3-5) for concentration and separation. The suspended solids and microorganisms in the wastewater are retained by the MBR membrane and retained in the MBR membrane separation tank (3-5) to become the concentrated liquid in the MBR membrane separation tank. The clear liquid that passes through the MBR membrane becomes the produced water and enters the subsequent treatment unit for further treatment. Part of the concentrated liquid from the MBR membrane separation tank is returned to the first-stage aerobic tank (3-2) as return sludge and enters the second-stage anoxic tank (3-4) with the water flow to achieve denitrification. Another part of the concentrated liquid from the MBR membrane separation tank is sent to the sludge treatment system (7) as residual sludge for concentration, dehydration and drying. Step S4: Advanced oxidation treatment stage Step S41: the produced water of the MBR membrane separation tank (3-5) then enters the ozone catalytic oxidation tank (4-1) for oxidation treatment. The ozone catalytic oxidation tank (4-1) is connected to the ozone generator (4-2). Under the action of the catalyst, the ozone is decomposed to generate hydroxyl free radicals ·OH with stronger oxidation effect, thereby oxidizing and decomposing the difficult biodegradable organic matter in the wastewater to generate organic matter that is easily decomposed and utilized by microorganisms; Step S5: Post-biological treatment stage Step S51: The effluent from the ozone catalytic oxidation tank (4-1) then passes through the moving bed bioreactor (5-1) and the high-efficiency sedimentation tank (5-2) in sequence. MBBR biological fillers are placed in the moving bed bioreactor (5-1). The surface of the fillers is easy to fix microbial film, so the surface of the fillers has both anoxic and aerobic zones, so that the remaining ammonia nitrogen and nitrate nitrogen in the wastewater are further removed by nitrification and denitrification; The clear liquid enters the high-efficiency sedimentation tank (5-2), where coagulants and flocculants are added. The suspended and colloidal solids remaining in the influent are transformed into flocs with larger particles and easier to precipitate under the action of the coagulants and flocculants, and then are precipitated and removed. The precipitated sludge produced in the high-efficiency sedimentation tank (5-2) is sent to the sludge treatment system (7) for concentration, dehydration and drying. Step S6: Nanofiltration treatment stage Step S61: The clear liquid after treatment in the high-efficiency sedimentation tank (5-2) enters the immersed ultrafilter (6-1) for filtration. The liquid that passes through the ultrafiltration membrane becomes clear liquid through a vacuum suction pump, while the remaining bacteria and suspended particles are retained on the surface of the ultrafiltration membrane as filter membranes. The sludge trapped on the surface of the ultrafiltration membrane is removed and discharged through backwashing or washing. Step S62: The ultrafiltration effluent enters the nanofiltration filter (6-2) for further treatment to obtain a higher quality filtered clear liquid; Step S63: The nanofiltration effluent enters the disinfection tank (6-3), and after disinfectant is added to the disinfection tank (6-3) for disinfection treatment, the water is pumped to various water points for reuse or directly discharged; The concentrated water produced by the nanofiltration is returned to the ozone catalytic oxidation tank (4-1) for further oxidation treatment; When the effluent water quality of ultrafiltration meets the requirements, the ultrafiltration effluent can be directly discharged into the disinfection tank through surpassing nanofiltration.

2. The device for treating the ultra-low concentration discharge of Maotai-flavor liquor production wastewater according to claim 1 is characterized in that: In the step S1, the pretreatment stage includes a rotary mechanical fine screen (1-1), two self-cleaning rotary fine screens (1-2), a regulating tank (1-3), a primary sedimentation tank (1-4) and a flotation tank (1-5); The rotary mechanical fine grid (1-1) adopts a rake tooth mechanical structure, the gap width of the rake tooth mechanical structure is 1-5 mm, and is used to remove larger particles, including husks and debris particles; The two self-cleaning rotary fine screens (1-2) both adopt a rotary drum structure, and the screen gap is 0.2-1 mm, which is used to remove fine solids, including solids in husks, wine lees and sorghum seeds; The primary sedimentation tank (1-4) is in the form of a conventional sedimentation tank. A reaction zone is provided in the primary sedimentation tank (1-4). A dephosphorizing agent is added in the reaction zone. The dephosphorizing agent can react with phosphate to generate phosphate precipitates. The flotation tank (1-5) is in the form of a conventional flotation tank, a reaction zone is set in the flotation tank, a coagulant and a flocculant are added to the reaction zone, The sludge treated in the primary sedimentation tank (1-4) and the scum treated in the flotation tank (1-5) are sent to the sludge treatment system (7) for concentration, dehydration and drying.

3. The ultra-low concentration discharge treatment equipment for Maotai-flavor liquor production wastewater according to claim 2 is characterized in that: The dephosphorizing agent includes one of ferric salt, ferrous salt or aluminum salt composed of sulfuric acid or hydrochloric acid; The coagulant is polyferric sulfate (PFS), polyaluminium chloride (PAC), or other iron-based or aluminium-based coagulants, and the flocculant is polyacrylamide (PAM).

4. The ultra-low concentration discharge treatment equipment for Maotai-flavor liquor production wastewater according to claim 1 is characterized in that: In the step S2, the anaerobic treatment stage includes an upflow UASB anaerobic reactor (2-1), a biogas storage tank (2-2), a biogas burner (2-3) and an anaerobic sludge sedimentation tank (2-4); The UASB anaerobic reactor (2-1) is provided with an anaerobic reaction zone and a gas-liquid-solid three-phase separation zone, and the top of the UASB anaerobic reactor (2-1) is connected to a biogas storage tank (2-2) and a biogas burner (2-3); Part of the sludge in the anaerobic sludge sedimentation tank (2-4) is returned to the water inlet area of ​​the UASB anaerobic reactor (2-1), and the other part is sent to the sludge treatment system (7) as residual sludge for concentration, dehydration and drying; Wastewater enters from the bottom of the UASB anaerobic reactor (2-1) and flows upward, driving the anaerobic sludge into a suspended state. The gas-carrying sludge is lighter and floats up faster, while the sludge becomes heavier after the gas is released and sinks. This can form an internal circulation of the sludge and play a mixing role. In the anaerobic treatment stage of step S2, organic matter in the wastewater generates methane gas under the action of anaerobic microorganisms in the anaerobic reaction zone, and the methane gas is separated from the liquid phase as a gas phase in the three-phase separation zone and enters the biogas storage tank (2-2) for storage; The biogas stored in the biogas storage tank (2-2) is delivered to a biogas user through a biogas pipeline or burned by a biogas burner (2-3), thereby eliminating the harm of methane gas to the environment and generating heat energy for utilization; The liquid from the gas-liquid-solid separation zone leaves the UASB anaerobic reactor (2-1) through a connecting pipe and enters the anaerobic sludge sedimentation tank (2-4) for further solid-liquid separation, and the anaerobic sludge carried out in the separation liquid is then pumped back to the UASB anaerobic reactor (2-1) for utilization, and the clear precipitated liquid enters the next treatment system for further treatment.

5. The ultra-low concentration discharge treatment equipment for Maotai-flavor liquor production wastewater according to claim 4 is characterized in that: The biogas storage tank adopts a water-sealed tank to ensure the pressure inside the biogas tank is stable.

6. The ultra-low concentration discharge treatment equipment for Maotai-flavor liquor production wastewater according to claim 4 is characterized in that: The heat energy generated by the combustion of the biogas is transferred to the reaction liquid in the anaerobic reaction zone through a heat exchanger arranged in the UASB anaerobic reactor (2-1), so as to increase the temperature of the sludge reaction liquid.

7. The ultra-low concentration discharge treatment equipment for Maotai-flavor liquor production wastewater according to claim 1 is characterized in that: In the step S3, the secondary AO treatment system used in the secondary biochemical treatment stage includes a first-stage anoxic tank (3-1), a first-stage aerobic tank (3-2), a second-stage anoxic tank (3-3), a second-stage aerobic tank (3-4) and an MBR membrane separation tank (3-5); An internal reflux is arranged between the first-stage anoxic pool (3-1) and the first-stage aerobic pool (3-2), and the internal reflux adopts 3-6 times of the treatment flow rate to return the nitrified liquid in the first-stage aerobic pool to the first-stage anoxic pool for denitrification; In order to ensure the effect of denitrification and the TN reaching the standard, a part of the effluent from the anaerobic sludge sedimentation tank bypasses the first-stage anoxic tank (3-1) and the first-stage aerobic tank (3-2) and directly enters the second-stage anoxic tank (3-3) to supplement the denitrification carbon source of the second-stage anoxic tank (3-4); An MBR membrane is arranged in the MBR membrane separation tank (3-5), and the MBR membrane adopts a special microfiltration membrane to intercept sludge or microorganisms in the MBR membrane separation tank (3-5); Part of the mixed liquid in the MBR separation tank (3-5) is returned to the first-stage aerobic tank (3-2) as return sludge, and the other part is sent to the sludge treatment system (7) as residual sludge for concentration, dehydration and drying; the filtered clear liquid of the MBR membrane is sent to the next-stage treatment system as the treated liquid for further treatment.

8. The ultra-low concentration discharge treatment equipment for Maotai-flavor liquor production wastewater according to claim 1 is characterized in that: In step S4, the advanced oxidation treatment stage includes an ozone catalytic oxidation tank (4-1) and an ozone generator (4-2), and the ozone catalytic oxidation tank (4-1) is connected to the ozone generator (4-2); The internal catalyst bed of the ozone catalytic oxidation tank (4-1) is filled with a non-supported ozone oxidation catalyst. Under the action of the catalyst, ozone is decomposed to generate hydroxyl free radicals ·OH (E 0 =2.8V), oxidatively decompose the difficult-to-biodegrade organic matter in the wastewater to generate easily biodegradable organic matter; The non-supported ozone oxidation catalyst comprises a silicon-aluminum-based material combined with a catalytic metal. A circulation system is provided in the ozone catalytic oxidation tank (4-1) to prevent the catalyst bed from being blocked. The flow rate of the circulating liquid is 50-100% of the treatment flow rate. The circulating backwashing arrangement of the ozone catalytic oxidation tank increases the speed at which wastewater passes through the catalyst bed and prevents the catalyst bed from being blocked.

9. The method and equipment for treating ultra-low concentration discharge of Maotai-flavor liquor production wastewater according to claim 1, characterized in that: In the step S5, the post-biological treatment stage includes a moving bed bioreactor (5-1) and a high-efficiency sedimentation tank (5-2); MBBR biological filler is placed in the moving bed bioreactor (5-1). The MBBR filler is made of PE material, generally has a diameter of 2.5 cm, a density of nearly 1, and is placed in the reaction tank at a volume of about 40%; The surface of the moving bed bioreactor (5-1) is easy to fix microbial film, so the surface of the filler has both anoxic zone and aerobic zone, thereby improving the denitrification effect of the moving bed bioreactor (5-1); Coagulant and flocculant are added into the high-efficiency sedimentation tank (4-2), and the precipitated sludge produced by the high-efficiency sedimentation tank (4-2) is sent to the sludge treatment system (7) for concentration, dehydration and drying.

10. The ultra-low concentration discharge treatment equipment for Maotai-flavor liquor production wastewater according to claim 1, characterized in that: In the step S6, the nanofiltration treatment stage includes an immersed ultrafilter (6-1), a nanofilter (6-2) and a disinfection tank (6-3); The membrane pore size of the ultrafiltration component used in the submerged ultrafilter (6-1) is 0.01-0.1 micrometers, which is used to ensure that bacteria and suspended particles are filtered out. The ultrafiltration component is submerged and uses a vacuum pump to suck out water; The nanofiltration (6-2) is used as a safeguard to obtain a higher quality filtered clear liquid; the concentrated water produced by the nanofiltration is returned to the ozone catalytic oxidation tank (4-1) for further oxidation treatment; the nanofiltration effluent enters the disinfection tank (6-3), and after disinfection treatment by adding a disinfectant to the disinfection tank (6-3), it is then sent to each reuse water use point through a reuse water pump for reuse or direct discharge.

Images