CN111559838B - Treatment method of aircraft paint surface cleaning wastewater - Google Patents

Treatment method of aircraft paint surface cleaning wastewater Download PDF

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CN111559838B
CN111559838B CN202010675234.1A CN202010675234A CN111559838B CN 111559838 B CN111559838 B CN 111559838B CN 202010675234 A CN202010675234 A CN 202010675234A CN 111559838 B CN111559838 B CN 111559838B
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tank
wastewater
water
sludge
effluent
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CN111559838A (en
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陈超
王英
苏辉
冯逸喆
晁毅
熊永志
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China Railway Construction Engineering Group Co Ltd
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China Railway Construction Engineering Group Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/24—Treatment of water, waste water, or sewage by flotation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/5281—Installations for water purification using chemical agents
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/76—Treatment of water, waste water, or sewage by oxidation with halogens or compounds of halogens
    • C02F1/766—Treatment of water, waste water, or sewage by oxidation with halogens or compounds of halogens by means of halogens other than chlorine or of halogenated compounds containing halogen other than chlorine
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F2001/007—Processes including a sedimentation step
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/30—Organic compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/22—O2
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/04—Disinfection
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/02—Aerobic processes
    • C02F3/12—Activated sludge processes
    • C02F3/1236—Particular type of activated sludge installations
    • C02F3/1268—Membrane bioreactor systems
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/28—Anaerobic digestion processes

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  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Separation Of Suspended Particles By Flocculating Agents (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

A treatment method of aircraft paint surface cleaning wastewater comprises the following steps: (1) collecting and adjusting waste water; (2) pretreating wastewater; (3) biological treatment of wastewater; (4) and (3) sludge treatment: (5) and (5) recycling the wastewater. The treatment method can efficiently and environmentally treat the cleaning wastewater generated before the final assembly of the airplane is sprayed, can flexibly change the treatment process according to the component change of the cleaning wastewater while ensuring the effluent quality, and can realize the recycling of wastewater resources.

Description

Treatment method of aircraft paint surface cleaning wastewater
Technical Field
The invention relates to the field of industrial wastewater treatment, in particular to a method for treating wastewater generated during cleaning of an aircraft paint surface.
Background
With the development of society and economy, the demand for long-distance travel and goods transportation is increasing, and large-sized airplanes are concerned by various countries with good economy, safety and convenience, and become the development direction of the aviation industry. The large-scale aircraft is huge in size, has a large number of parts, needs to be processed and manufactured in sections, is transported to a general assembly factory, is assembled and debugged according to the navigation requirement, and finally finishes paint spraying delivery. The segmented structure of the airplane is generally required to be sprayed with primer after being manufactured in a factory, and then a temporary protective layer is coated on the surface of the segmented structure, so that the phenomenon that a paint film is broken in the transportation process and the metal surface is corroded is avoided. And after the aircraft reaches a final assembly factory, the temporary protective layer needs to be removed by using a cleaning agent, and patterns and names of an airline company are integrally sprayed on the outer surface of the aircraft after the aircraft is assembled.
At present, the surface of the substrate of the airplane part is generally provided with a zinc-rich primer, wherein the zinc-rich primer contains a high proportion of zinc powder, so that the zinc powder can effectively protect an organism made of aluminum alloy, and in the extreme case of paint film breakage, the zinc powder can also play a role in sacrificing an anode and reducing the organism corrosion. The temporary protective layer on the zinc-rich primer is usually a cured coating of epoxy resin, epoxy phenolic resin, polyester, polyurethane material or a thermoplastic coating containing ethylene acrylic resin and vinyl resin, and the coating layer has good chemical corrosion resistance and can provide a protective layer for the primer to slow down and limit the invasion of water vapor, oxygen and chemically active ions.
In the general assembly procedure of an airplane, a temporary protective layer on the surface of an airplane primer is usually removed by adopting a high-pressure spray cleaning agent, and the cleaning agent mainly comprises an organic solvent, a surfactant, a penetrating agent, an acidic cleaning agent, an alkaline assistant, a defoaming agent and the like. In the cleaning process, a large amount of clear water mixed cleaning agent is required to be repeatedly sprayed and washed on the surface of the airplane part until the temporary protective layer is completely removed. Organic wastewater containing aromatic substances, alkane substances, polymer resin particles, zinc powder particles, a surfactant and the like can be generated in the cleaning process. The wastewater has the characteristics of high organic matter content, poor biochemical treatment effect and difficult removal of metal particle components, and if a general activated sludge method sewage treatment process is adopted, the defects of slow start of an activated sludge treatment system, poor sludge settling property, large fluctuation of effluent quality, difficult standard discharge and the like exist, and the wastewater is difficult to adapt to the novel industrial production requirements of reducing wastewater discharge and fully recycling water resources in an airplane general assembly plant. With the continuous construction and commissioning of the aircraft assembly plant in China in recent years and the rapid improvement of the aircraft assembly capacity, the exploration of an efficient and environment-friendly treatment method for the aircraft paint surface cleaning wastewater becomes a problem to be solved urgently.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a method for treating aircraft paint surface cleaning wastewater. The method can effectively remove metal particle substances in the wastewater, improve the biodegradability of the wastewater, adapt to the changes of the water quantity and the water quality of the wastewater, ensure that the effluent is discharged and recycled after reaching the standard, and provide a referential treatment mode for reducing the wastewater discharge and recycling water resources in an aircraft assembly plant.
In order to achieve the aim, the invention provides a method for treating aircraft paint cleaning wastewater, which comprises the following steps:
a treatment method of aircraft paint surface cleaning wastewater comprises the following steps:
(1) collecting and adjusting waste water; waste water containing pollutants generated by cleaning treatment before airplane final assembly paint spraying is collected by a drainage ditch and then pumped into a waste water adjusting tank through a ground waste water pump, and an aeration device and a stirring device are arranged in the adjusting tank and used for oxygenating and stirring the waste water so as to adjust the water quantity and homogenize the water quality;
(2) pretreating wastewater; the wastewater in the wastewater adjusting tank is separated from large solid particles by a grid and then enters a mixing reaction tank, and alkaline substances are firstly added into the mixing reaction tank to ensure that Zn in water2+Formation of Zn (OH)2Then adding a coagulant, carrying out coagulation stirring, adding a flocculating agent after the steady state of the particulate matters which are difficult to precipitate in the water is damaged, allowing the wastewater after the flocculation stirring to flow into an air floatation tank, and effectively removing insoluble organic matters and residual suspended matters through air floatation;
(3) biological treatment of wastewater; the effluent of the air floatation tank enters a hydrolysis acidification tank, an aeration device, a stirring device and a suspension filler are arranged in the tank, and when the tank normally works, the tank is kept in an anoxic environment, so that the refractory organic pollutants are subjected to hydrolysis reaction, the biodegradability of the wastewater is improved, and the effluent of the hydrolysis acidification tank enters an MBR (membrane bioreactor) for further biological treatment and finally reaches the discharge standard; when the total nitrogen in the effluent of the membrane bioreactor exceeds the standard, stopping aeration in the hydrolysis acidification tank, only stirring to form an anaerobic environment, promoting growth of denitrifying bacteria, forming an A/O process with a subsequent membrane bioreactor, and performing denitrification treatment; when the total nitrogen content in the effluent of the membrane bioreactor is low and the organic matter content is high, the aeration stirring in the hydrolysis acidification tank is increased to form an aerobic environment, so that the aerobic treatment capacity is increased;
(4) and (3) sludge treatment: collecting sludge in the air flotation tank, the hydrolysis acidification tank and the MBR membrane bioreactor into a sludge tank, storing and standing, pumping supernatant into a wastewater adjusting tank, pumping bottom concentrated sludge into a sludge modification tank through a sludge pump, adding a sludge dehydrating agent, further performing a cross-linking polymerization reaction, finally pressing into a mud cake through a screw-type sludge dewatering machine, and storing the mud cake in a mud storage area for further harmless treatment;
(5) and (3) recycling of wastewater: effluent meeting the discharge standard of the MBR membrane bioreactor is stored in a reuse water tank, one part of the effluent is reused in a pressurizing gas dissolving device in the air floatation tank to prepare high-pressure gas dissolving water, and the other part of the effluent is used for cleaning a membrane component in the MBR membrane bioreactor.
Preferably, in the step (1), the aeration device in the wastewater regulating tank is a compressed air perforated pipe with the aperture of 2-4mm, and the stirring device in the wastewater regulating tank is an axial submersible stirrer.
In any of the above schemes, preferably, in the step (2), the mixing reaction tank is sequentially divided into 3 reaction tanks along the water flow direction, the liquid level is controlled by overflow, wherein a grid with grid bars at a distance of 1mm is arranged in front of a water inlet of the first reaction tank, an alkaline substance adding device, a pH meter and an axial submersible stirrer are arranged in the first reaction tank, NaOH, KaOH or slaked lime is added into the wastewater, the pH value in the first reaction tank is controlled to be 7.5 to less than pH <9.5, a coagulant adding device and an axial submersible stirrer are arranged in the second reaction tank, an aluminum coagulant is added into the wastewater, a flocculant adding device and an axial submersible stirrer are arranged in the third reaction tank, and anionic polyacrylamide with a relative molecular mass of 1000-1500 ten thousand is added into the wastewater.
In any of the above schemes, preferably, in the step (2), the effluent of the mixed reaction tank enters an air flotation tank for flocculating constituent separation, the dissolved air water in the air flotation tank is prepared by utilizing the standard discharge water after the wastewater treatment is finished, the water amount of the dissolved air water is 40-60% of the treated water amount of the air flotation tank, and the effluent water collecting area of the air flotation tank is provided with KH2PO4Adding equipment for detecting COD of the effluent of the air floatation tankcr、BOB5TKN and TP, when TP/TKN<When 0.2 hour, KH is added into the effluent of the air flotation tank2PO4。
In any of the above schemes, preferably, in the step (3), a membrane type aeration head and a DO monitor are arranged in the hydrolysis acidification tank, a sludge stirring pump is arranged at the bottom of the tank, and a porous suspended biological filler is also put in the hydrolysis acidification tank.
In any of the above schemes, preferably, in the step (3), the membrane module in the MBR membrane bioreactor adopts a flat membrane, and the membrane flux adopts 0.2-0.3m3/m2 .d, the lift H of the membrane suction pump is more than or equal to 8m, a membrane type aeration head is arranged under the membrane component, and a reflux pump is also arranged in the MBR membrane bioreactor and is used for refluxing the sludge-water mixture in the reactor to the hydrolysis acidification tank.
In any of the above schemes, preferably, in the step (3), the wall and the bottom of the reaction tank of the MBR membrane bioreactor are paved with grid-shaped electric tracing heating equipment and are externally coated with a heat preservation layer, and when the liquid level is higher than the working liquid level by 0.5m and lower than 8 ℃, the MBR membrane bioreactor is started, and when the liquid level is lower than the working liquid level by 0.5m and higher than 18.5 ℃, the MBR membrane bioreactor is closed.
In any of the above schemes, preferably, in the step (3), indexes such as CODcr, TN, TP and the like in the effluent of the MBR membrane bioreactor are detected, and when the concentration of the CODcr is higher than the discharge standard and the concentration of the TN is lower than the discharge standard, the aeration amount of the membrane type aeration head in the hydrolysis acidification tank is increased to form a part of aerobic environment so as to improve the treatment capacity of organic pollutants; when the concentration of CODcr is lower than the discharge standard and the concentration of TN is higher than the discharge standard, the lift of a membrane filter pump is reduced, a reflux pump is started to reflux the wastewater in the MBR membrane bioreactor into a hydrolysis acidification tank, the reflux amount is 50-200% of the water treatment amount of the hydrolysis acidification tank, the aeration amount of a membrane type aeration head in the hydrolysis acidification tank is closed or reduced, and a sludge stirring pump at the bottom of the tank is started to form a partial anaerobic environment so as to improve the removal capacity of total nitrogen.
In any of the above embodiments, preferably, in the step (4), the sludge tank is provided with a compressed air perforated pipe to perform timed aeration on the sludge, and the sludge-dewatering agent added to the sludge-modifying tank is cationic polyacrylamide having a high relative molecular mass of 1700 ten thousand or more.
In any of the above schemes, preferably, in the step (5), the standard-reaching discharge water in the reuse water pool is added with chlorine-containing disinfectant for disinfection and then is reused in the pressurized gas dissolving device.
The invention has the beneficial effects that:
1. the method for treating the waste water can efficiently and environmentally treat a large amount of waste water generated during the cleaning of the paint surface of the airplane, can flexibly change the treatment process according to the component change of the cleaning waste water while ensuring the quality of the effluent water, and can realize the recycling of waste water resources.
2. The MBR membrane bioreactor can effectively ensure the stability of the effluent quality, overcome the characteristics of poor sludge settling performance and difficult sludge-water separation during the biological treatment of the cleaning wastewater, reduce the space required by a treatment device and ensure simpler and more convenient operation and control.
3. According to the invention, aiming at the characteristic of high concentration of zinc particles in the cleaning wastewater before spraying paint on the airplane, the zinc particles can be effectively removed, and the phenomenon that metal particles adhere to the surface of a membrane component to influence the filtration performance of the membrane and aggravate the pollution degree of the membrane is avoided.
4. Aiming at the characteristics of high content of organic matters such as resin, surfactant and the like and poor biodegradability in wastewater, a hydrolysis acidification step is added after air floatation separation and before an MBR (membrane bioreactor), and the dissolved oxygen concentration in a hydrolysis acidification tank and the microscopic growth environment of microorganisms can be changed by controlling aeration amount, adding suspended biological filler, stirring the tank bottom and the like, so that proper growth conditions are provided for aerobic, anoxic and anaerobic bacteria. Through monitoring the concentration of the pollutants, the running state in the hydrolysis acidification tank is adjusted, and the linkage coordination effect with the MBR membrane bioreactor is better exerted so as to adapt to the change of the components and the concentration of the pollutants in the wastewater.
Detailed Description
The technical solutions of the present application will be described in detail below with reference to specific embodiments of the present application, but the following examples are only for understanding the present invention, and the embodiments and features of the embodiments in the present application may be combined with each other, and the technical solutions of the present application are not limited to the following examples, and may be implemented in various different ways as defined and covered by the claims.
Example 1
A method for treating cleaning wastewater before spraying paint on an airplane comprises the following steps:
(1) collecting and adjusting waste water; all the pollutant-containing self-use water and overflow and emptying wastewater generated by cleaning treatment before spraying paint on the airplane are collected by a drainage ditch and then pumped into a wastewater adjusting tank by a ground wastewater pump, and an aeration device and a stirring device are arranged in the adjusting tank and used for oxygenating and stirring the wastewater so as to adjust the water quantity and homogenize the water quality and reduce the impact influence on the subsequent treatment steps caused by the fluctuation of the water quantity and the water quality;
(2) pretreating wastewater; separating large solid particles from the wastewater in the wastewater adjusting tank through a grid, feeding the wastewater into a mixing reaction tank, and adding alkaline substances into the mixing reaction tank to ensure that Zn in the water2+Formation of Zn (OH)2Precipitating, then adding a coagulant, carrying out coagulation stirring, adding a flocculating agent after the steady state of the particulate matters which are difficult to precipitate in the water is destroyed, flowing the wastewater after flocculation stirring into an air floatation tank, and effectively removing insoluble organic matters and residual suspended matters through air floatation;
(3) biological treatment of wastewater; the effluent of the air floatation tank enters a hydrolysis acidification tank, an aeration device, a stirring device and a suspension filler are arranged in the tank, and when the tank normally works, the tank is kept in an anoxic environment, so that the refractory organic pollutants are subjected to hydrolysis reaction, the biodegradability of the wastewater is improved, and the effluent of the hydrolysis acidification tank enters an MBR (membrane bioreactor) for further biological treatment and finally reaches the discharge standard; when the total nitrogen in the effluent of the membrane bioreactor exceeds the standard, stopping aeration in the hydrolysis acidification tank, only stirring to form an anaerobic environment, promoting growth of denitrifying bacteria, forming an A/O process with a subsequent aerobic tank, and performing denitrification treatment; when the total nitrogen content in the effluent of the membrane bioreactor is low and the organic matter content is high, the aeration stirring in the hydrolysis acidification tank is increased to form an aerobic environment, so that the aerobic treatment capacity is increased;
(4) and (3) sludge treatment: collecting sludge in the air flotation tank, the hydrolysis acidification tank and the MBR membrane bioreactor into a sludge tank, storing and standing, collecting supernatant through a ground wastewater ditch, pumping the supernatant into a wastewater adjusting tank, pumping bottom concentrated sludge into a sludge modification tank through a sludge pump, adding a sludge dehydrating agent, further performing cross-linking polymerization reaction, finally pressing the sludge into a mud cake through a screw-type sludge dehydrator, and storing the mud cake in a mud storage area for further harmless treatment;
(5) and (3) recycling of wastewater: effluent meeting the discharge standard of the MBR membrane bioreactor is stored in a reuse water tank, one part of the effluent is recycled to a pressurizing gas dissolving device in an air floatation tank after chlorination for preparing high-pressure gas dissolving water, and the other part of the effluent is used for membrane cleaning of the MBR membrane bioreactor.
In step (1), the aeration device in the wastewater adjusting tank is a compressed air perforated pipe with the aperture of 2mm, on one hand, the dissolved oxygen concentration in water can be improved through the aeration of the perforated pipe, the phenomenon that oxygen deficiency occurs when the wastewater is stored in the adjusting tank for too long time is avoided, on the other hand, the turbulent fluctuation of water flow can be enhanced, the mixing effect of the wastewater is improved, and besides, the Zn in the wastewater can be converted into Zn by improving the dissolved oxygen concentration through the aeration in the wastewater adjusting tank2+And is convenient to be removed from the wastewater through subsequent reaction. The stirring device in the wastewater adjusting tank is an axial submersible stirrer, so that the mixing effect of wastewater and the oxygenation effect of aeration of the perforated pipe can be further improved.
In the step (2), the mixing reaction tank is sequentially divided into 3 reaction tanks along the water flow direction, the liquid level is controlled by overflow, a grating with the interval of 1mm between bars is arranged in front of a water inlet of the first reaction tank, large granular substances in the wastewater, such as paint coats, gravels and the like are isolated outside the reaction tank, an alkaline substance adding device, a pH meter and an axial submersible stirrer are arranged in the first reaction tank, NaOH is added into the wastewater, and the pH value in the first reaction tank is controlled to be 8.0<pH<8.5, Zn in water2+Formation of Zn (OH)2A floc.
The treated water in the first reaction tank overflows and falls to a second reaction tank, coagulant adding equipment and an axial submersible stirrer are arranged in the second reaction tank, and polyaluminium chloride (PAC) is added into the wastewater to destroy the stable state of particulate matters which are not easy to precipitate, such as resin particles and grease particles.
And the treated water of the second reaction tank overflows and falls to a third reaction tank, a flocculating agent adding device and an axial submersible stirrer are arranged in the third reaction tank, a flocculating agent is added into the wastewater to further play a bridging role of the high polymer, and the destabilized suspended particles are aggregated on the high polymer flocs and separated from the water. The flocculating agent can select anionic polyacrylamide with high relative molecular mass, the relative molecular mass of which is 1000-1500 ten thousand.
And (3) in the step (2), the effluent of the mixed reaction tank enters an air floatation tank for flocculating constituent separation. The water amount of the dissolved air water in the air flotation tank is 40 percent of the water amount treated by the air flotation tank. The water collecting area of the water outlet of the air floatation tank is provided with KH2PO4Adding equipment for detecting COD of the effluent of the air floatation tankcrBOB5, TKN and TP, when TP/TKN<When 0.2 hour, KH is added into the effluent of the air flotation tank2PO4And mixing and flowing to a hydrolysis acidification pool.
And (3) arranging a diaphragm type aeration head and a DO monitor in the hydrolysis acidification tank, and arranging a sludge stirring pump at the bottom of the tank. Meanwhile, a porous suspended biological filler is added into the hydrolysis acidification tank, a larger specific surface area is provided by a porous structure, an adsorption growth environment is provided for microorganisms, the sludge concentration in the hydrolysis acidification tank is favorably improved, the wastewater treatment capacity is increased, a biological film with a certain thickness is favorably formed on the surface of the biological filler, different dissolved oxygen concentration gradients are formed along the thickness direction of the biological film, and a proper growth environment is provided for aerobic bacteria, anaerobic bacteria and facultative bacteria.
In the step (3), the membrane component in the MBR membrane bioreactor adopts a flat membrane, and the membrane flux adopts 0.23/m2 .d, the lift H =8m of the membrane suction pump, a membrane type aeration head is arranged under the membrane component, and bubbles are stirred upwards to form turbulent flow on the surface of the membrane during aeration, so that the blockage of the membrane can be effectively relieved. And a reflux pump is also arranged in the MBR membrane bioreactor and is used for refluxing the muddy water mixture in the reactor to the hydrolysis acidification tank.
In the step (3), grid-shaped electric tracing heating equipment is paved on the wall and the bottom of the reaction tank of the MBR membrane bioreactor, and a heat insulation layer is coated outside the reaction tank, so that the total heat consumption is 16 KW. The electric heating system arranged in the MBR membrane bioreactor can effectively avoid the influence on the biodegradation capacity of the activated sludge due to temperature fluctuation, especially rapid temperature drop, ensure the membrane flux in extreme environment, delay the membrane pollution speed and ensure the effluent quality. The device is interlocked with the liquid level and the temperature sensor of the MBR membrane bioreactor to operate, and is started when the liquid level is 0.5m higher than the working liquid level and lower than 8 ℃, and is closed when the liquid level is 0.5m lower than the working liquid level or higher than 18.5 ℃.
Detecting COD in effluent of MBR (membrane bioreactor)crIndexes such as TN and TP, as CODcrWhen the concentration of the DO is higher than the discharge standard, namely 500mg/L, and the concentration of the TN is lower than the discharge standard, namely 35mg/L, the aeration quantity of the membrane type aeration head in the hydrolysis acidification tank is increased, and the DO concentration in the hydrolysis acidification tank is increased to be more than 2mg/L from 0.5mg/L, so that a part of aerobic environment is formed, and the treatment capacity of organic pollutants is improved. When the concentration of CODcr is lower than the discharge standard, namely 500mg/L, and the TN concentration is higher than the discharge standard, namely 35mg/L, the lift of a membrane filter pump is reduced, a reflux pump is started, wastewater in an MBR membrane bioreactor flows back to a first reaction tank of a hydrolysis acidification tank, the reflux amount is 50% -200% of the treatment water amount of the hydrolysis acidification tank, the aeration amount of a membrane aeration head in the hydrolysis acidification tank is closed or reduced, a sludge stirring pump at the bottom of the tank is started, and the DO concentration in the hydrolysis acidification tank is reduced from 0.5mg/L to below 0.2mg/L, so that a partial anaerobic environment is formed, and the total nitrogen removal capacity is improved.
And (4) providing a compressed air perforated pipe in the sludge tank to perform timed aeration on the sludge so as to prevent the sludge from floating upwards to influence settleability due to anaerobic reaction generated in the standing process of the sludge. The sludge dehydrating agent added in the sludge modification tank is cationic polyacrylamide with high relative molecular mass, and the relative molecular mass is more than 1700 ten thousand.
In the step (5), one part of the discharged water reaching the standard in the reuse water tank is reused in a pressurizing gas dissolving device in the air floatation tank to prepare high-pressure gas dissolving water after being disinfected by adding sodium hypochlorite, and the other part of the discharged water is used for cleaning the membrane of the MBR membrane bioreactor.
Example 2
A method for treating cleaning wastewater before spraying paint on an airplane comprises the following steps:
(1) collecting and adjusting waste water; all the pollutant-containing self-use water and overflow and emptying wastewater generated by cleaning treatment before spraying paint on the airplane are collected by a drainage ditch and then pumped into a wastewater adjusting tank by a ground wastewater pump, and an aeration device and a stirring device are arranged in the adjusting tank and used for oxygenating and stirring the wastewater so as to adjust the water quantity and homogenize the water quality and reduce the impact influence on the subsequent treatment steps caused by the fluctuation of the water quantity and the water quality;
(2) pretreating wastewater; separating large solid particles from the wastewater in the wastewater adjusting tank through a grid, feeding the wastewater into a mixing reaction tank, and adding alkaline substances into the mixing reaction tank to ensure that Zn in the water2+Formation of Zn (OH)2Precipitating, then adding a coagulant, carrying out coagulation stirring, adding a flocculating agent after the steady state of the particulate matters which are difficult to precipitate in the water is destroyed, flowing the wastewater after flocculation stirring into an air floatation tank, and effectively removing insoluble organic matters and residual suspended matters through air floatation;
(3) biological treatment of wastewater; the effluent of the air floatation tank enters a hydrolysis acidification tank, an aeration device, a stirring device and a suspension filler are arranged in the tank, and when the tank normally works, the tank is kept in an anoxic environment, so that the refractory organic pollutants are subjected to hydrolysis reaction, the biodegradability of the wastewater is improved, and the effluent of the hydrolysis acidification tank enters an MBR (membrane bioreactor) for further biological treatment and finally reaches the discharge standard; when the total nitrogen in the effluent of the membrane bioreactor exceeds the standard, stopping aeration in the hydrolysis acidification tank, only stirring to form an anaerobic environment, promoting growth of denitrifying bacteria, forming an A/O process with a subsequent aerobic tank, and performing denitrification treatment; when the total nitrogen content in the effluent of the membrane bioreactor is low and the organic matter content is high, the aeration stirring in the hydrolysis acidification tank is increased to form an aerobic environment, so that the aerobic treatment capacity is increased;
(4) and (3) sludge treatment: collecting sludge in the air flotation tank, the hydrolysis acidification tank and the MBR membrane bioreactor into a sludge tank, storing and standing, collecting supernatant through a ground wastewater ditch, pumping the supernatant into a wastewater adjusting tank, pumping bottom concentrated sludge into a sludge modification tank through a sludge pump, adding a sludge dehydrating agent, further performing cross-linking polymerization reaction, finally pressing the sludge into a mud cake through a screw-type sludge dehydrator, and storing the mud cake in a mud storage area for further harmless treatment;
(5) and (3) recycling of wastewater: effluent meeting the discharge standard of the MBR membrane bioreactor is stored in a reuse water tank, one part of the effluent is recycled to a pressurizing gas dissolving device in an air floatation tank after chlorination for preparing high-pressure gas dissolving water, and the other part of the effluent is used for membrane cleaning of the MBR membrane bioreactor.
In step (1), the aeration device in the wastewater adjusting tank is a compressed air perforated pipe with the aperture of 4mm, on one hand, the dissolved oxygen concentration in water can be improved through the aeration of the perforated pipe, the phenomenon that oxygen deficiency occurs when the wastewater is stored in the adjusting tank for too long time is avoided, on the other hand, the turbulent fluctuation of water flow can be enhanced, the mixing effect of the wastewater is improved, and besides, the Zn in the wastewater can be converted into Zn by improving the dissolved oxygen concentration through the aeration in the wastewater adjusting tank2+And is convenient to be removed from the wastewater through subsequent reaction. The stirring device in the wastewater adjusting tank is an axial submersible stirrer, so that the mixing effect of wastewater and the oxygenation effect of aeration of the perforated pipe can be further improved.
In the step (2), the mixing reaction tank is sequentially divided into 3 reaction tanks along the water flow direction, the liquid level is controlled by overflow, a grating with the interval of 1mm between bars is arranged in front of a water inlet of the first reaction tank, large granular substances in the wastewater, such as paint coats, gravels and the like are isolated outside the reaction tank, an alkaline substance adding device, a pH meter and an axial submersible stirrer are arranged in the first reaction tank, slaked lime is added into the wastewater, and the pH value in the first reaction tank is controlled to be 7.5<pH<8.5 making Zn in Water2+Formation of Zn (OH)2A floc.
The treated water in the first reaction tank overflows and falls to a second reaction tank, coagulant adding equipment and an axial submersible stirrer are arranged in the second reaction tank, coagulant is added into the wastewater to destroy the stable state of particulate matters which are difficult to precipitate in the water, such as resin particles and grease particles, and the coagulant selects poly-phosphorus-aluminum chloride as the coagulant.
The poly-aluminum chlorophosphate can be prepared by the following method: in Al3+Dropping NaOH solution into 0.3mol/L aluminum chloride solution, dropping sodium dihydrogen phosphate solution, controlling the molar ratio of the dropped P to Al in the solution to be 0.1-0.2, refluxing for 3-4 hours at 80-85 deg.C to obtain Al with alkalization degree of 2%, and adjusting pH value of the solution to be 2%3+The concentration of the poly-phosphorus aluminum chloride is 0.26 mol/L.
Phosphate radical anion parachlorine is introduced into poly-phosphorus aluminum chlorideThe aluminum oxide is modified, on one hand, the condensation effect is improved through the complexing polymerization of phosphate radical, on the other hand, the pH range of the poly-phosphorus aluminum chloride which exerts the condensation effect is wider than that of common poly-aluminum chloride, and Zn (OH) can not be influenced2On the premise of the floc, the grease particles and the resin particles are better demulsified to be beneficial to subsequent flocculation and precipitation.
And the treated water of the second reaction tank overflows and falls to a third reaction tank, a flocculating agent adding device and an axial submersible stirrer are arranged in the third reaction tank, a flocculating agent is added into the wastewater to further play a bridging role of the high polymer, and the destabilized suspended particles are aggregated on the high polymer flocs and separated from the water. The flocculant is prepared by modifying and polymerizing acrylamide.
The amphoteric polymeric flocculant can be prepared by the following method: acrylamide, sodium acrylate and 2-acrylimido-2-methylpropane trimethyl ammonium chloride are dissolved in water, 3 percent NaCl solution is added, the temperature is raised to 30 ℃ under the protection of inert gas, ammonium persulfate solution is slowly dripped, the temperature is raised to 90-100 ℃ after reaction is carried out for 30min, and the reaction is continued for 2-3 hours.
The amphoteric polymer flocculant obtained by polyacrylamide modified polymerization contains anionic groups and cationic groups, wherein the cationic groups are convenient for being combined with negatively charged organic suspended matters such as grease and resin, and the anionic groups are beneficial to promoting inorganic flocs such as Zn (OH)2Compared with common anionic polyacrylamide, the sedimentation of the third reaction tank can ensure good sedimentation effect within a wider range of pH, and the pH value in the third reaction tank is within a range of 7-10 through detection of a pH meter, so that good flocculation effect can be obtained, and the pH value of the effluent of the second reaction tank is not required to be adjusted under normal conditions.
And (3) in the step (2), the effluent of the mixed reaction tank enters an air floatation tank for flocculating constituent separation. The dissolved gas water in the air flotation tank is prepared by selectively utilizing the standard discharge water after the wastewater treatment is finished, and the water amount of the dissolved gas water is 50 percent of the water amount treated by the air flotation tank. The water collecting area of the water outlet of the air floatation tank is provided with KH2PO4Adding equipment, detecting air-float poolCOD of the effluentcrBOB5, TKN and TP, when TP/TKN<When 0.2 hour, KH is added into the effluent of the air flotation tank2PO4And mixing and flowing to a hydrolysis acidification pool.
And (3) arranging a diaphragm type aeration head and a DO monitor in the hydrolysis acidification tank, and arranging a sludge stirring pump at the bottom of the tank. Meanwhile, a porous suspended biological filler is added into the hydrolysis acidification tank, a larger specific surface area is provided by a porous structure, an adsorption growth environment is provided for microorganisms, the sludge concentration in the hydrolysis acidification tank is favorably improved, the wastewater treatment capacity is increased, a biological film with a certain thickness is favorably formed on the surface of the biological filler, different dissolved oxygen concentration gradients are formed along the thickness direction of the biological film, and a proper growth environment is provided for aerobic bacteria, anaerobic bacteria and facultative bacteria.
In the step (3), the membrane component in the MBR membrane bioreactor adopts a flat membrane, and the membrane flux adopts 0.3m3/m2 .d, the lift H =10m of the membrane suction pump, a membrane type aeration head is arranged under the membrane component, and bubbles are stirred upwards to form turbulent flow on the surface of the membrane during aeration, so that the blockage of the membrane can be effectively relieved. And a reflux pump is also arranged in the MBR membrane bioreactor and is used for refluxing the muddy water mixture in the reactor to the hydrolysis acidification tank.
And (3) paving grid-shaped electric tracing heating equipment on the wall and the bottom of the reaction tank of the MBR membrane bioreactor, and coating a heat insulation layer outside the reaction tank, wherein the total heat consumption is 20 KW. The electric heating system arranged in the MBR membrane bioreactor can effectively avoid the influence on the biodegradation capacity of the activated sludge due to temperature fluctuation, especially rapid temperature drop, ensure the membrane flux in extreme environment, delay the membrane pollution speed and ensure the effluent quality. The device is interlocked with the liquid level and the temperature sensor of the MBR membrane bioreactor to operate, and is started when the liquid level is 0.5m higher than the working liquid level and lower than 8 ℃, and is closed when the liquid level is 0.5m lower than the working liquid level or higher than 18.5 ℃.
Detecting COD in effluent of MBR (membrane bioreactor)crIndexes such as TN and TP, as CODcrIs higher than the discharge standard, i.e. 500mg/L, and TN is lower than the discharge standard, i.e. 35mg/L, the water is increasedThe aeration quantity of the membrane type aeration head in the hydrolysis acidification tank is increased from 0.5mg/L to 3mg/L to form partial aerobic environment, so that the treatment capacity of organic pollutants is improved. When the concentration of CODcr is lower than the discharge standard, namely 500mg/L, and the TN concentration is higher than the discharge standard, namely 35mg/L, the lift of a membrane filter pump is reduced, a reflux pump is started, wastewater in an MBR membrane bioreactor flows back into a first reaction tank of a hydrolysis acidification tank, the reflux amount is 100% of the water treatment amount of the hydrolysis acidification tank, the aeration amount of a membrane type aeration head in the hydrolysis acidification tank is closed, a sludge stirring pump at the bottom of the tank is started, the DO concentration in the hydrolysis acidification tank is reduced from 0.5mg/L to 0.1mg/L, and a partial anaerobic environment is formed to improve the total nitrogen removal capacity.
And (4) providing a compressed air perforated pipe in the sludge tank to perform timed aeration on the sludge so as to prevent the sludge from floating upwards to influence settleability due to anaerobic reaction generated in the standing process of the sludge. The sludge dehydrating agent added in the sludge modification tank is cationic polyacrylamide with high relative molecular mass, and the relative molecular mass is more than 1700 ten thousand.
In the step (5), the discharged water reaching the standard in the reuse water tank is reused in a pressurizing gas dissolving device in the air floatation tank to prepare high-pressure gas dissolving water after chlorine-containing compound disinfectant is added. The chlorine-containing composite disinfectant is prepared by mixing water solutions of sulfamic acid, dimethylhexanone ureide and chloramine, wherein the molar ratio of the sulfamic acid to the dimethylhexanone ureide to the chloramine is 2:1: 6.
The up-to-standard discharged water in the reuse water pool still contains organic pollutants and microorganisms with certain concentration, the organic pollutants and the microorganisms are recycled to the pressurizing container tank and easily grow in a large amount under the condition of high DO, so that a biological membrane is formed near the tank body and the pressurizing gas nozzle, the effective solvent and the gas dissolving efficiency are reduced, the chlorine or sodium hypochlorite is directly used for sterilization, the defects of short action time, high reduction of the concentration of residual chlorine and the like exist, the sulfamic acid and the dimethylcaprolactoyl urea can firstly react with free chlorine during preparation of the medicament by adding the sulfamic acid and the dimethylcaprolactol urea, and a reaction product is gradually hydrolyzed after adding the reuse water and then releases the free chlorine again, so that the effect of continuous. In addition, the dimethylcaproyl urea is added, so that a certain protection effect can be achieved on a pressurized container, and the corrosion of acidic dissolved gas water is avoided.
Example 3
A method for treating cleaning wastewater before spraying paint on an airplane comprises the following steps:
(1) collecting and adjusting waste water; all the pollutant-containing self-use water and overflow and emptying wastewater generated by cleaning treatment before spraying paint on the airplane are collected by a drainage ditch and then pumped into a wastewater adjusting tank by a ground wastewater pump, and an aeration device and a stirring device are arranged in the adjusting tank and used for oxygenating and stirring the wastewater so as to adjust the water quantity and homogenize the water quality and reduce the impact influence on the subsequent treatment steps caused by the fluctuation of the water quantity and the water quality;
(2) pretreating wastewater; separating large solid particles from the wastewater in the wastewater adjusting tank through a grid, feeding the wastewater into a mixing reaction tank, and adding alkaline substances into the mixing reaction tank to ensure that Zn in the water2+Formation of Zn (OH)2Precipitating, then adding a coagulant, carrying out coagulation stirring, adding a flocculating agent after the steady state of the particulate matters which are difficult to precipitate in the water is destroyed, flowing the wastewater after flocculation stirring into an air floatation tank, and effectively removing insoluble organic matters and residual suspended matters through air floatation;
(3) biological treatment of wastewater; the effluent of the air floatation tank enters a hydrolysis acidification tank, an aeration device, a stirring device and a suspension filler are arranged in the tank, and when the tank normally works, the tank is kept in an anoxic environment, so that the refractory organic pollutants are subjected to hydrolysis reaction, the biodegradability of the wastewater is improved, and the effluent of the hydrolysis acidification tank enters an MBR (membrane bioreactor) for further biological treatment and finally reaches the discharge standard; when the total nitrogen in the effluent of the membrane bioreactor exceeds the standard, stopping aeration in the hydrolysis acidification tank, only stirring to form an anaerobic environment, promoting growth of denitrifying bacteria, forming an A/O process with a subsequent aerobic tank, and performing denitrification treatment; when the total nitrogen content in the effluent of the membrane bioreactor is low and the organic matter content is high, the aeration stirring in the hydrolysis acidification tank is increased to form an aerobic environment, so that the aerobic treatment capacity is increased;
(4) and (3) sludge treatment: collecting sludge in the air flotation tank, the hydrolysis acidification tank and the MBR membrane bioreactor into a sludge tank, storing and standing, collecting supernatant through a ground wastewater ditch, pumping the supernatant into a wastewater adjusting tank, pumping bottom concentrated sludge into a sludge modification tank through a sludge pump, adding a sludge dehydrating agent, further performing cross-linking polymerization reaction, finally pressing the sludge into a mud cake through a screw-type sludge dehydrator, and storing the mud cake in a mud storage area for further harmless treatment;
(5) and (3) recycling of wastewater: effluent meeting the discharge standard of the MBR membrane bioreactor is stored in a reuse water tank, one part of the effluent is recycled to a pressurizing gas dissolving device in an air floatation tank after chlorination for preparing high-pressure gas dissolving water, and the other part of the effluent is used for membrane cleaning of the MBR membrane bioreactor.
In step (1), the aeration device in the wastewater adjusting tank is a compressed air perforated pipe with the aperture of 3mm, on one hand, the dissolved oxygen concentration in water can be improved through the aeration of the perforated pipe, the phenomenon that oxygen deficiency occurs when the wastewater is stored in the adjusting tank for too long time is avoided, on the other hand, the turbulent fluctuation of water flow can be enhanced, the mixing effect of the wastewater is improved, and besides, the Zn in the wastewater can be converted into Zn by improving the dissolved oxygen concentration through the aeration in the wastewater adjusting tank2+And is convenient to be removed from the wastewater through subsequent reaction. The stirring device in the wastewater adjusting tank is an axial submersible stirrer, so that the mixing effect of wastewater and the oxygenation effect of aeration of the perforated pipe can be further improved.
In the step (2), the mixing reaction tank is sequentially divided into 3 reaction tanks along the water flow direction, the liquid level is controlled by overflow, a grating with the interval of 1mm between bars is arranged in front of a water inlet of the first reaction tank, large granular substances in the wastewater, such as paint coats, gravels and the like are isolated outside the reaction tank, an alkaline substance adding device, a pH meter and an axial submersible stirrer are arranged in the first reaction tank, slaked lime is added into the wastewater, and the pH value in the first reaction tank is controlled to be 8.0<pH<9.5 making Zn in Water2+Formation of Zn (OH)2A floc.
The treated water in the first reaction tank overflows and falls to a second reaction tank, coagulant adding equipment and an axial submersible stirrer are arranged in the second reaction tank, coagulant is added into the wastewater to destroy the stable state of particulate matters which are difficult to precipitate in the water, such as resin particles and grease particles, and the coagulant selects poly-phosphorus-aluminum chloride as the coagulant.
The poly-aluminum chlorophosphate can be prepared by the following method: in Al3+Dropping NaOH solution into 0.3mol/L aluminum chloride solution, dropping sodium dihydrogen phosphate solution, controlling the molar ratio of the dropped P to Al in the solution to be 0.1-0.2, refluxing for 3-4 hours at 80-85 deg.C to obtain Al with alkalization degree of 2%, and adjusting pH value of the solution to be 2%3+The concentration of the poly-phosphorus aluminum chloride is 0.26 mol/L.
The poly-phosphorus aluminum chloride introduces phosphate anions to modify aluminum chloride, on one hand, the condensation effect is improved through the complex polymerization of phosphate, on the other hand, the pH range of poly-phosphorus aluminum chloride exerting the condensation effect is wider than that of common poly-aluminum chloride, and Zn (OH) can not be influenced2On the premise of the floc, the grease particles and the resin particles are better demulsified to be beneficial to subsequent flocculation and precipitation.
And the treated water of the second reaction tank overflows and falls to a third reaction tank, a flocculating agent adding device and an axial submersible stirrer are arranged in the third reaction tank, a flocculating agent is added into the wastewater to further play a bridging role of the high polymer, and the destabilized suspended particles are aggregated on the high polymer flocs and separated from the water. The flocculant is prepared by modifying and polymerizing acrylamide.
The amphoteric polymeric flocculant can be prepared by the following method: acrylamide, sodium acrylate and 2-acrylimido-2-methylpropane trimethyl ammonium chloride are dissolved in water, 3 percent NaCl solution is added, the temperature is raised to 30 ℃ under the protection of inert gas, ammonium persulfate solution is slowly dripped, the temperature is raised to 90-100 ℃ after reaction is carried out for 30min, and the reaction is continued for 2-3 hours.
The amphoteric polymer flocculant obtained by polyacrylamide modified polymerization contains anionic groups and cationic groups, wherein the cationic groups are convenient for being combined with negatively charged organic suspended matters such as grease and resin, and the anionic groups are beneficial to promoting inorganic flocs such as Zn (OH)2Compared with common anionic polyacrylamide, the method can ensure good sedimentation effect within a wider pH rangeThe pH value in the third reaction tank is in the range of 7-10 through pH meter detection, good flocculation effect can be obtained, and the pH value of the effluent of the second reaction tank is not required to be adjusted under normal conditions.
And (3) in the step (2), the effluent of the mixed reaction tank enters an air floatation tank for flocculating constituent separation. The dissolved gas water in the floatation tank is prepared by selectively utilizing the standard-reaching discharge water after the wastewater treatment is finished, and the water amount of the dissolved gas water is 60 percent of the water amount treated by the floatation tank. The water collecting area of the water outlet of the air floatation tank is provided with KH2PO4Adding equipment for detecting COD of the effluent of the air floatation tankcrBOB5, TKN and TP, when TP/TKN<When 0.2 hour, KH is added into the effluent of the air flotation tank2PO4And mixing and flowing to a hydrolysis acidification pool.
And (3) arranging a diaphragm type aeration head and a DO monitor in the hydrolysis acidification tank, and arranging a sludge stirring pump at the bottom of the tank. Meanwhile, a porous suspended biological filler is added into the hydrolysis acidification tank, a larger specific surface area is provided by a porous structure, an adsorption growth environment is provided for microorganisms, the sludge concentration in the hydrolysis acidification tank is favorably improved, the wastewater treatment capacity is increased, a biological film with a certain thickness is favorably formed on the surface of the biological filler, different dissolved oxygen concentration gradients are formed along the thickness direction of the biological film, and a proper growth environment is provided for aerobic bacteria, anaerobic bacteria and facultative bacteria.
In the step (3), the membrane component in the MBR membrane bioreactor adopts a flat membrane, and the membrane flux adopts 0.3m3/m2 .d, the lift H =12m of the membrane suction pump, a membrane type aeration head is arranged under the membrane component, and bubbles are stirred upwards to form turbulent flow on the surface of the membrane during aeration, so that the blockage of the membrane can be effectively relieved. And a reflux pump is also arranged in the MBR membrane bioreactor and is used for refluxing the muddy water mixture in the reactor to the hydrolysis acidification tank.
And (3) paving grid-shaped electric tracing heating equipment on the wall and the bottom of the reaction tank of the MBR membrane bioreactor, and coating a heat insulation layer outside the reaction tank, wherein the total heat consumption is 24 KW. The electric heating system arranged in the MBR membrane bioreactor can effectively avoid the influence on the biodegradation capacity of the activated sludge due to temperature fluctuation, especially rapid temperature drop, ensure the membrane flux in extreme environment, delay the membrane pollution speed and ensure the effluent quality. The device is interlocked with the liquid level and the temperature sensor of the MBR membrane bioreactor to operate, and is started when the liquid level is 0.5m higher than the working liquid level and lower than 8 ℃, and is closed when the liquid level is 0.5m lower than the working liquid level or higher than 18.5 ℃.
Detecting COD in effluent of MBR (membrane bioreactor)crIndexes such as TN and TP, as CODcrWhen the concentration of the DO is higher than the discharge standard, namely 500mg/L, and the concentration of the TN is lower than the discharge standard, namely 35mg/L, the aeration quantity of the membrane type aeration head in the hydrolysis acidification tank is increased, and the DO concentration in the hydrolysis acidification tank is increased from 0.5mg/L to 4mg/L, so that a part of aerobic environment is formed, and the treatment capacity of organic pollutants is improved. When the concentration of CODcr is lower than the discharge standard, namely 500mg/L, and the TN concentration is higher than the discharge standard, namely 35mg/L, the lift of a membrane filter pump is reduced, a reflux pump is started, wastewater in an MBR membrane bioreactor flows back into a first reaction tank of a hydrolysis acidification tank, the reflux amount is 150% of the water treatment amount of the hydrolysis acidification tank, the aeration amount of a membrane type aeration head in the hydrolysis acidification tank is reduced, a sludge stirring pump at the bottom of the tank is started, the DO concentration in the hydrolysis acidification tank is reduced from 0.5mg/L to 0.2mg/L, and a partial anaerobic environment is formed to improve the total nitrogen removal capacity.
And (4) providing a compressed air perforated pipe in the sludge tank to perform timed aeration on the sludge so as to prevent the sludge from floating upwards to influence settleability due to anaerobic reaction generated in the standing process of the sludge. The sludge dehydrating agent added in the sludge modification tank is cationic polyacrylamide with high relative molecular mass, and the relative molecular mass is more than 1700 ten thousand.
In the step (5), the discharged water reaching the standard in the reuse water tank is reused in a pressurizing gas dissolving device in the air floatation tank to prepare high-pressure gas dissolving water after chlorine-containing compound disinfectant is added. The chlorine-containing composite disinfectant is prepared by mixing water solutions of sulfamic acid, dimethylhexanone ureide and chloramine, wherein the molar ratio of the sulfamic acid to the dimethylhexanone ureide to the chloramine is 1:1: 4.
The up-to-standard discharged water in the reuse water pool still contains organic pollutants and microorganisms with certain concentration, the organic pollutants and the microorganisms are recycled to the pressurizing container tank and easily grow in a large amount under the condition of high DO, so that a biological membrane is formed near the tank body and the pressurizing gas nozzle, the effective solvent and the gas dissolving efficiency are reduced, the chlorine or sodium hypochlorite is directly used for sterilization, the defects of short action time, high reduction of the concentration of residual chlorine and the like exist, sulfamic acid and dimethylcaprolactol urea can react with free chlorine firstly during preparation of the medicament by adding the sulfamic acid and the dimethylcaprolactol urea, and reaction products are gradually hydrolyzed after adding the reuse water and release the free chlorine again, so that the effect of continuous sterilization is achieved. In addition, the dimethylcaproyl urea is added, so that a certain protection effect can be achieved on a pressurized container, and the corrosion of acidic dissolved gas water is avoided.
In addition, in order to achieve better technical effects, the technical solutions in the above embodiments may be combined arbitrarily to meet various requirements of practical applications.
According to the embodiment, the treatment method disclosed by the invention is used for carrying out targeted treatment on the characteristics of the waste water generated by cleaning before the paint spraying of the airplane, and a feasible scheme and a beneficial reference are provided for how to efficiently and environmentally treat the waste water generated by cleaning the paint surface of the airplane.
According to the invention, the MBR membrane bioreactor is adopted as a biological treatment unit, so that the effluent quality can be effectively ensured to reach the standard, the characteristics of poor sludge settling property and difficulty in sludge-water separation caused by high content of resin and surfactant in the cleaning wastewater can be overcome, higher activated sludge concentration and treatment efficiency are ensured, the space required by sludge separation is reduced, the space required by a treatment device is reduced, and the operation control is more convenient.
Aiming at the characteristic of high concentration of zinc particles in the cleaning wastewater before spraying paint on the airplane, firstly, aeration and stirring are added in the steps of collecting and adjusting the wastewater to promote the zinc particles to be converted into zinc ions, so that the phenomenon that metal particles are attached to the surface of a membrane component of a subsequent MBR membrane bioreactor to influence the membrane filtration performance, aggravate the membrane pollution degree and influence the membrane cleaning on the recovery effect of the membrane filtration function is avoided; secondly, the pH is firstly adjusted in the pretreatment process of the mixed reaction tank, and Zn (OH) is formed after full stirring2Flocculating agent and flocculating agent are added to improve the removal of zinc ionsAnd (4) treating the effect.
In the invention, the waste water has high content of organic matters such as resin, surfactant and the like and has reacted to generate Zn (OH)2The flocculating constituent is characterized in that the aluminium polyphosphate is selected as the flocculating agent, and the acrylamide is modified and polymerized to obtain the amphoteric polymeric flocculant, so that the flocculating constituent can further improve the polymerization capability compared with the traditional aluminium polyphosphate and polymeric polyacrylamide, can react in a wider pH range and ensure good settling property, does not need to adjust the pH values of a second reaction tank and a third reaction tank in a mixed reaction tank again, and avoids Zn (OH)2The possibility of re-dissolution of flocs due to pH range variations.
Aiming at the characteristic that the surfactant is easy to generate bubbles in the wastewater, and considering the settling property of flocs obtained in the mixing reaction tank, the air floatation method is adopted for solid-liquid separation, so that insoluble organic matters and suspended matters can be separated simply and efficiently, and meanwhile, the water discharged by the MBR membrane bioreactor reaching the standard is used as water-dissolved water, so that the using amount of fresh water can be reduced, and water resources are fully utilized. In addition, the chlorine-containing compound disinfectant can effectively overcome the defects that the recycled water is easy to breed bacteria, pollute the gas dissolving equipment and reduce the gas dissolving efficiency, and ensure the safe and reliable supply of the gas dissolving water.
Aiming at the characteristics of high organic matter content and poor biodegradability of resin, surfactant and the like in wastewater, in order to reduce the enrichment of organic matters which are difficult to degrade on the surface of a membrane component, avoid the rapid reduction of the membrane filtration performance, shorten the membrane cleaning period and influence the treatment efficiency of an MBR (membrane bioreactor) and the quality of effluent water, after the air floatation separation is completed, a hydrolysis acidification step is added, and the dissolved oxygen concentration in a hydrolysis acidification tank and the microcosmic growth environment of microorganisms can be changed by controlling the aeration amount, adding suspended biological fillers, stirring the tank bottom and the like, so that a proper growth condition is provided for aerobic, anoxic and anaerobic bacteria. Through monitoring the concentration of the pollutants, the running state in the hydrolysis acidification tank is adjusted, and the linkage coordination effect with the MBR membrane bioreactor is better exerted so as to adapt to the change of the components and the concentration of the pollutants in the wastewater.
According to the invention, the MBR membrane bioreactor is provided with the heating equipment and the heat-insulating layer, so that the influence of the biodegradation capacity of the temperature fluctuation sludge can be effectively avoided, the membrane pollution speed is delayed, and the effluent quality is ensured. The control mode linked with the temperature and the liquid level can be used quickly and accurately, and management and operation are facilitated.
The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.

Claims (8)

1. The method for treating the aircraft paint surface cleaning wastewater is characterized by comprising the following steps of:
(1) collecting and adjusting waste water; waste water containing pollutants generated by cleaning treatment before airplane final assembly paint spraying is collected by a drainage ditch and then pumped into a waste water adjusting tank through a ground waste water pump, and an aeration device and a stirring device are arranged in the adjusting tank and used for oxygenating and stirring the waste water so as to adjust the water quantity and homogenize the water quality;
(2) pretreating wastewater; the wastewater in the wastewater adjusting tank is separated from large solid particles by a grid and then enters a mixing reaction tank, and alkaline substances are firstly added into the mixing reaction tank to ensure that Zn in water2+Formation of Zn (OH)2Then adding a coagulant, carrying out coagulation stirring, adding a flocculating agent after the steady state of the particulate matters which are difficult to precipitate in the water is damaged, flowing the wastewater after the flocculation stirring into an air floatation tank, and effectively removing insoluble organic matters and residual suspended matters through air floatation;
(3) biological treatment of wastewater; the effluent of the air floatation tank enters a hydrolysis acidification tank, an aeration device, a stirring device and a suspension filler are arranged in the tank, and when the tank normally works, the tank is kept in an anoxic environment, so that the refractory organic pollutants are subjected to hydrolysis reaction, the biodegradability of the wastewater is improved, and the effluent of the hydrolysis acidification tank enters an MBR (membrane bioreactor) for further biological treatment and finally reaches the discharge standard; when the total nitrogen in the effluent of the membrane bioreactor exceeds the standard, stopping aeration in the hydrolysis acidification tank, only stirring to form an anaerobic environment, promoting growth of denitrifying bacteria, forming an A/O process with a subsequent membrane bioreactor, and performing denitrification treatment; when the total nitrogen content in the effluent of the membrane bioreactor is low and the organic matter content is high, the aeration stirring in the hydrolysis acidification tank is increased to form an aerobic environment, so that the aerobic treatment capacity is increased;
(4) and (3) sludge treatment: collecting sludge in the air flotation tank, the hydrolysis acidification tank and the MBR membrane bioreactor into a sludge tank, storing and standing, pumping supernatant into a wastewater adjusting tank, pumping bottom concentrated sludge into a sludge modification tank through a sludge pump, adding a sludge dehydrating agent, further performing a cross-linking polymerization reaction, finally pressing into a mud cake through a screw-type sludge dewatering machine, and storing the mud cake in a mud storage area for further harmless treatment;
(5) and (3) recycling of wastewater: effluent meeting the discharge standard of the MBR membrane bioreactor is stored in a reuse water tank, one part of the effluent is reused in a pressurized dissolved air device in an air floatation tank to prepare high-pressure dissolved air water, and the other part of the effluent is used for cleaning a membrane component in the MBR membrane bioreactor;
in the step (2), the mixing reaction tank is sequentially divided into 3 reaction tanks along the water flow direction, the liquid level is controlled by overflow, a grating with the interval of grid bars being 1mm is arranged in front of a water inlet of the first reaction tank, an alkaline substance adding device, a pH meter and an axial submersible stirrer are arranged in the first reaction tank, NaOH, KaOH or hydrated lime is added into the wastewater, and the pH value in the first reaction tank is controlled to be 7.5<pH<9.5, coagulant adding equipment and an axial submersible stirrer are arranged in the second reaction tank, and poly-phosphorus aluminum chloride is added into the wastewater as coagulant, and is prepared by the following method: in Al3+Dropping NaOH solution into 0.3mol/L aluminum chloride solution, dropping sodium dihydrogen phosphate solution, controlling the molar ratio of the dropped P to Al in the solution to be 0.1-0.2, refluxing for 3-4 hours at 80-85 deg.C to obtain Al with alkalization degree of 2%, and adjusting pH value of the solution to be 2%3+Poly-phosphorus aluminium chloride with concentration of 0.26mol/L, a flocculating agent adding device and a shaft are arranged in the third reaction tankAdding an amphoteric polymeric flocculant obtained by modifying and polymerizing acrylamide into wastewater into a submersible stirrer, wherein the amphoteric polymeric flocculant is prepared by the following method: dissolving acrylamide, sodium acrylate and 2-acrylimido-2-methylpropane trimethyl ammonium chloride in water, adding 3% NaCl solution, heating to 30 ℃ under the protection of inert gas, slowly dropwise adding ammonium persulfate solution, reacting for 30min, heating to 90-100 ℃ and continuously reacting for 2-3 h;
in the step (3), CODcr, TN and TP indexes in effluent of the MBR membrane bioreactor are detected, and when the concentration of CODcr is higher than a discharge standard and the concentration of TN is lower than the discharge standard, the aeration amount of the membrane type aeration head in the hydrolysis acidification tank is increased to form a part of aerobic environment so as to improve the treatment capacity of organic pollutants; when the concentration of CODcr is lower than the discharge standard and the concentration of TN is higher than the discharge standard, the lift of a membrane filter pump is reduced, a reflux pump is started to reflux the wastewater in the MBR membrane bioreactor into a hydrolysis acidification tank, the reflux amount is 50-200% of the water treatment amount of the hydrolysis acidification tank, the aeration amount of a membrane type aeration head in the hydrolysis acidification tank is closed or reduced, and a sludge stirring pump at the bottom of the tank is started to form a partial anaerobic environment so as to improve the removal capacity of total nitrogen.
2. The method for treating aircraft paint cleaning wastewater according to claim 1, wherein in the step (1), the aeration device in the wastewater conditioning tank is a compressed air perforated pipe with the aperture of 2-4mm, and the stirring device in the wastewater conditioning tank is an axial submersible stirrer.
3. The method for treating wastewater from cleaning aircraft paint surfaces according to claim 1, wherein in the step (2), the effluent of the mixed reaction tank enters the flotation tank for flocculation separation, the water content of the dissolved gas in the flotation tank is prepared by using the standard discharge water after the wastewater treatment is finished, the water content of the dissolved gas is 40-60% of the treated water content of the flotation tank, and the effluent collecting area of the flotation tank is provided with KH2PO4Adding equipment for detecting COD of the effluent of the air floatation tankcr、BOB5TKN and TP indices when TP/TKN<When 0.2 hour, KH is added into the effluent of the air flotation tank2PO4。
4. The method for treating the aircraft paint cleaning wastewater according to claim 1, wherein in the step (3), a diaphragm type aeration head and a DO monitor are arranged in the hydrolysis acidification tank, a sludge stirring pump is arranged at the bottom of the hydrolysis acidification tank, and a porous suspended biological filler is added into the hydrolysis acidification tank.
5. The method for treating aircraft paint surface cleaning wastewater according to claim 1, wherein in the step (3), a membrane module in an MBR (membrane bioreactor) adopts a flat membrane, and the membrane flux adopts 0.2-0.3m3/ m2.d, the lift H of the membrane suction pump is more than or equal to 8m, a membrane type aeration head is arranged under the membrane component, and a reflux pump is also arranged in the MBR membrane bioreactor and is used for refluxing the sludge-water mixture in the reactor to the hydrolysis acidification tank.
6. The method for treating the aircraft paint surface cleaning wastewater according to claim 1, wherein in the step (3), the reaction tank walls and the tank bottom of the MBR membrane bioreactor are paved with grid-shaped electric tracing heating equipment and are externally coated with an insulating layer, and the MBR membrane bioreactor is started when the liquid level is 0.5m higher than the working liquid level and is lower than 8 ℃, and is closed when the liquid level is 0.5m lower than the working liquid level or is higher than 18.5 ℃.
7. The method for treating aircraft paint cleaning wastewater according to claim 1, wherein in the step (4), a compressed air perforated pipe is arranged in a sludge pond to perform timed aeration on sludge, and the sludge dehydrating agent added in the sludge modification tank is cationic polyacrylamide with high relative molecular mass of 1700 ten thousand or more.
8. The method for treating the aircraft paint surface cleaning wastewater according to claim 1, wherein in the step (5), the qualified discharged water in the reuse water pool is added with a chlorine-containing disinfectant for disinfection and then is reused in a pressurized gas dissolving device.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101423313A (en) * 2008-11-14 2009-05-06 山西大学 Fluorescent whitening agent production waste water treatment process
CN209322663U (en) * 2018-11-28 2019-08-30 广州中科建禹环保有限公司 A kind of wastewater treatment integrated apparatus
CN211004981U (en) * 2019-09-11 2020-07-14 佛山市叶绿体环保科技有限公司 Paint spraying wastewater circulating treatment system

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TW200925126A (en) * 2007-12-07 2009-06-16 Ind Tech Res Inst Sequencing batch membrane bioreactor dealing device and method thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101423313A (en) * 2008-11-14 2009-05-06 山西大学 Fluorescent whitening agent production waste water treatment process
CN209322663U (en) * 2018-11-28 2019-08-30 广州中科建禹环保有限公司 A kind of wastewater treatment integrated apparatus
CN211004981U (en) * 2019-09-11 2020-07-14 佛山市叶绿体环保科技有限公司 Paint spraying wastewater circulating treatment system

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