CN100410193C - ADC foaming agent wastewater treatment method and integrated device - Google Patents

Abstract

The invention relates to wastewater treatment technology in environmental science and engineering, in particular to an ADC foaming agent wastewater treatment method and an integrated device. It is characterized by the combination of physicochemical method and biochemical method. The first part is physical and chemical method, which is pretreated by ultrasonic method, and the latter part is biochemical method. On the basis of DAT-IAT process, there is an anoxic pool (A) in front. That is to say, the A/DAT-IAT process is formed, and the front and rear parts are connected by the middle water storage tank. The structure of the present invention is compact, with the functions of water collection and water quality adjustment, biochemical reaction and sludge precipitation in one, short process flow, compact layout, easy to realize automation, and has the function of resisting toxicity, stable operation, high treatment efficiency and good water quality. advantage.

Description

ADC foaming agent wastewater treatment method and integrated device

technical field

The invention relates to wastewater treatment technology in environmental science and engineering, in particular to an ADC foaming agent wastewater treatment method and an integrated device.

Background technique

The chemical name of ADC foaming agent is azodicarbonamide (English name is Azodicarbonamide), and its molecular formula is C ₂ H ₄ O ₂ N ₂ . A large amount of nitrogen, an appropriate amount of carbon monoxide and a small amount of other gases such as carbon dioxide and ammonia. ADC is non-toxic, odorless, non-flammable, and has the characteristics of large gas generation, uniform bubbles, no pollution to products, non-toxic gas, no corrosion to molds, easy temperature control, and no influence on curing or molding speed. At present, the product is widely used as a foaming agent in the processing of polyvinyl chloride, polypropylene, polyethylene, polyamide, neoprene, natural rubber, nitrile rubber, silicone rubber and other plastics and rubbers.

ADC blowing agent wastewater is a high-concentration ammonia-nitrogen wastewater with complex components and difficult to degrade. The production process of ADC includes several stages: sodium hypochlorite synthesis, hydrazine synthesis, condensation, oxidation, etc. ADC wastewater mainly comes from the mother liquor discharged from the condensation section and biurea washing wastewater. If these high-concentration ammonia-nitrogen wastewater is directly discharged into the environment without treatment, it will cause water pollution, pose a threat to the survival of aquatic animals such as fish, stimulate the overgrowth of aquatic plants such as algae, and form eutrophication such as red tides, which will affect people's health. Life. There is no reliable treatment technology at home and abroad.

Existing processing method mainly contains physicochemical method, wherein Yao Cheng, Dai Qun, Zhou Xisheng's <ADC Foaming Agent Production Wastewater Treatment Technology and Research> (Journal of Pollution Prevention and Control Technology Volume 11 No. 3 Issue 1998.9) in the prior art, its The chemical method is adopted, and the materials used are lime and bleaching powder. Although this method has certain effects, the removal rate of ammonia nitrogen is only 35.4%, and the removal rate of chemical oxygen demand is only 78.1%. In addition, there is a large amount of secondary pollution such as lime slag. Another invention patent: <New Method for Comprehensive Utilization of ADC Foaming Agent Condensation Mother Liquor> (Patent No.: CN2005100382685), the principle of this method is to add alkali to strip, although it has a certain effect, but the disadvantage is that the amount of alkali consumed is too much , too much energy consumption.

Invention content:

The object of the present invention is to provide an ADC foaming agent wastewater treatment method and an integrated device capable of effectively treating high-concentration ammonia nitrogen wastewater.

It is characterized by the combination of physical and chemical methods and biochemical methods. The first part is physical and chemical methods. Ultrasonic methods are used for pretreatment, which can greatly reduce ammonia nitrogen and chemical oxygen demand, but cannot finally solve the problem. The latter part is the biochemical method. On the basis of the DAT-IAT process, there is an anoxic pool (A) in front, which forms the A/DAT-IAT process. After treatment, it can reach the national first-level emission standard. Sink to connect.

The device for realizing the method of the present invention: the preceding ultrasonic pretreatment equipment is mainly composed of four parts: an ultrasonic generator, an ultrasonic transducer, a water tank, and an aeration device, wherein the ultrasonic generator is a key component that determines the effect of wastewater treatment. The ultrasonic generator converts the usual power frequency into a high-frequency electrical signal above 20KHZ (generally 20KHZ to 10MHZ) and sends it to the ultrasonic transducer, thereby generating powerful ultrasonic vibrations and spreading them into the waste water, generating a series of Physical and chemical effects, which promote the degradation of chemical pollutants in wastewater. The following biochemical treatment equipment includes the aerobic-interstitial aeration tank of the front anaerobic tank, which is composed of anoxic tank, DAT tank and IAT tank in series. An intermediate water storage tank is set between the ultrasonic pretreatment equipment and the biochemical treatment equipment. The water storage tank is also equipped with a heating temperature control device to keep the temperature of the wastewater at 23-25 degrees Celsius; in addition, it is also equipped with a dosing device to continuously supply NaH ₂ PO ₄ to meet the needs of microorganisms for phosphorus; there is also a Inlet pipes for domestic sewage (or other carbon sources) to meet the carbon needs of microorganisms.

The principle of ultrasonic pretreatment is as follows: the ultrasonic wave propagation process is the process of alternating expansion and compression of waves. During the expansion period, ultrasonic waves have a negative pressure effect on the liquid, and the negative pressure applied to the liquid causes the liquid to break and generate cavities, forming Cavitation nucleation, the formation of gas-filled bubbles in a liquid, is known as cavitation. The bubbles produced by cavitation have a very short residence time, and they are immediately subjected to the pressure from the adjacent compression zone almost immediately after they are formed, causing these bubbles to collapse and disappear rapidly in a very short time, and generate local high temperature in the very small space around them (up to 5000K) and local high pressure (up to 50MPa), accompanied by strong shock waves and micro jets with a speed of up to 100m/s, these physical conditions provide an extremely favorable physical and chemical environment for the degradation of chemical pollutants in wastewater. On the one hand, the instantaneous high temperature and high pressure generated by the rapid collapse of the bubbles crack the water molecules in the bubbles into strong oxidizing free radicals such as H, HO, HO2 and H2O2:

H ₂ O→H·+HO·

H·+O ₂ →HO ₂ ·

2HO·→H ₂ O ₂

2HO ₂ →H ₂ O ₂ +O ₂

These strong oxidizing substances directly and indirectly act on the chemical pollutants in the water body and oxidize them into CO2, H2O, inorganic ions and other substances. On the other hand, due to the effects of shock waves and micro jets, pollutants can enter the bubbles and directly undergo pyrolysis reactions similar to combustion chemical reactions, and the degradation rate is relatively high.

When there is ammonia nitrogen in the water body, free ammonia can volatilize and enter the cavitation bubbles for direct pyrolysis, and at the same time be oxidized by free radicals in the main body of the liquid phase to generate N ₂ and N ₂ O, or generate nitrate and nitrite to remain in the air. In wastewater, the partial oxidation equation is as follows:

2NH ₃ +6HO→N ₂ +6H ₂ O

2NH ₃ +8HO→N ₂ O+7H ₂ O...

The principle of biochemical treatment is: A/DAT-IAT process is the same as the traditional activated sludge process, which uses microorganisms to decompose pollutants in wastewater to achieve the purpose of purifying water quality. Different from the traditional activated sludge method, the A/DAT-IAT process is composed of three reaction pools with different functions. The oxygen pool can also be regarded as the series connection of the A/O pool and the SBR pool. The anoxic pool is to improve the weakness of the low denitrification efficiency of the DAT-IAT process.

The structure of the present invention is compact, with the functions of water collection and water quality adjustment, biochemical reaction and sludge sedimentation in one body. A diversion wall is provided between the two pools, which avoids the hydraulic interference of the two pools and improves the hydraulic state. The IAT pool is almost in static sedimentation. Its sedimentation effect is better than that of the secondary sedimentation tank. The invention has short process flow, compact layout and easy automation. The operation of the A/DAT-IAT system has gone through the stages of aerobic, anoxic, anaerobic, and sedimentation. The dominant bacterial species were screened, the growth of filamentous bacteria was inhibited, and the sedimentation and dehydration performance of the sludge was good. The organic matter in the wastewater provides an additional carbon source for the denitrification stage. In addition, the alkalinity generated by the denitrification can be provided to the nitrification stage to neutralize the H+ produced in this stage. The A/DAT-IAT process is suitable for wastewater with large changes in water quantity and quality. It has the function of resisting toxicity, stable operation, high treatment efficiency, and good effluent quality. The IAT pool can be regarded as delayed aeration, and the load of organic matter is very low, which is conducive to the progress of nitrification reaction. In the precipitation stage, endogenous carbon can be used for denitrification reaction.

Description of drawings

Fig. 1 is the schematic diagram of ultrasonic method pretreatment equipment of the present invention

Figure 2 is a schematic diagram of biochemical treatment equipment

Figure 3 is a schematic perspective view of the main reactor of the biochemical treatment equipment

Fig. 4 is the overall schematic diagram of the integrated device of the present invention

1. Ultrasonic generator 2. Transducer 3. Water tank 4. Trachea and gas nozzle 5. Insulation layer 6. Water inlet 7. Water outlet 8. Fan 9. Water inlet pool 10. Water inlet pump 11. Agitator 12. Front partition Plate 13. Aeration head 14. Air compressor 15. Rear partition 16. Outlet pump 17. Outlet pool 18. Return pump 19. Ultrasonic equipment 21. Biochemical reactor 20. Intermediate water storage tank 22. Dosing device (N _a H ₂ PO ₄ ) 23. Heating thermostat 24. Domestic sewage (or other carbon sources) water inlet pipe

Detailed ways

The integrated device used in the present invention is composed of three parts: 1. The first part mainly includes an ultrasonic generator, an ultrasonic transducer and a water tank, wherein the ultrasonic generator is a key component for determining the wastewater treatment effect. The ultrasonic generator converts the usual power frequency into a high-frequency electrical signal above 20KHZ (generally 20KHZ to 10MHZ) and sends it to the ultrasonic transducer, thereby generating powerful ultrasonic vibrations and spreading them into the waste water, generating a series of Physical and chemical effects, which promote the degradation of chemical pollutants in wastewater. At the same time, in order to enhance the effect, an aeration device is attached to this part. The fan used is placed at the bottom, and the gas pipe and gas nozzle are arranged at the lower part. 2. The latter part is biochemical treatment equipment, which is mainly composed of three parts in series: the front anaerobic tank (A), the aerobic tank (DAT) and the interstitial aeration tank (IAT). 3. There is an intermediate water storage tank between the ultrasonic pretreatment equipment and the biochemical treatment equipment. The tank is equipped with a heating temperature control device, a dosing device and a water inlet device for domestic sewage.

The working process of the first part of wastewater treatment (as shown in Figure 1):

The waste water flows into the ultrasonic pretreatment equipment through the water inlet 6, and in the water tank 3, the concentration of ammonia nitrogen and chemical oxygen demand is greatly reduced due to the action of intense ultrasonic waves. This is because the ultrasonic generator 1 converts the usual power frequency into a high-frequency electrical signal above 20KHZ (generally 20KHZ to 10MHZ) and transmits it to the ultrasonic transducer 2, thereby generating powerful ultrasonic vibrations and spreading them into the waste water , produced a series of physical and chemical effects, and promoted the degradation of chemical pollutants in wastewater. At the same time, in order to enhance the effect, an aeration device is attached to this part, the air is sucked from the fan 8, and enters the waste water through the air pipe and the air nozzle 4. The periphery of equipment 5 has insulation layer, makes temperature keep on about 20 ℃. In this embodiment, the equipment of Xi'an Kangming Ultrasonic Company is used and assembled, the frequency used is 28KHZ, and the power is 300W. In addition, a small amount of Fenton's reagent needs to be added during the test.

Treated by this equipment, the high concentration of ammonia nitrogen in the ADC blowing agent can be reduced from 2000mg/L to 150mg/L, the removal rate is 92.5%, and the chemical oxygen demand can be reduced from 1000mg/L to 200mg/L removal rate 80%, and then through simple biological treatment, it can meet the national emission standards.

The working process of the latter part of wastewater treatment (as shown in Figure 2):

The waste water flows from the storage tank 9 into the anoxic pool (i.e. pool A) through the water inlet pump 10, and flows into the aerobic pool (i.e. the DAT pool) through the cavity of the front partition 12. The head 13 enters the aerobic pool, and the ammonia nitrogen in the waste water is oxidized into nitrate nitrogen, and the waste water flows into the anoxic pool through the backflow pump 18, where it is denitrified and escapes as nitrogen gas. The inflow to the aerobic pool is continuous. The wastewater in the aerobic tank flows into the gap aeration tank (i.e. IAT tank) through the cavity of the rear partition 15, and the wastewater in the tank flows into the outlet tank by the outlet pump 16 after four stages of water intake, aeration, sedimentation and drainage. 17. In this pond, the wastewater is further nitrified and denitrified as nitrogen gas escapes during the sedimentation stage. The pool is intermittent inflow and intermittent drainage.

According to many tests, when the temperature is 23-25°C, when the concentration of NH ₃ -N in the influent is 150mg/L, the concentration of NH ₃ -N in the effluent can reach 15mg/L, and the removal rate is 90%; when the concentration of COD in the influent is If it is 200mg/L, the concentration of COD in the effluent can reach below 10mg/L, and the removal rate is 95%. L, even so, the COD concentration of the effluent can still reach below 60mg/L; From the perspective of the test process, controlling the concentration of NH3-N in the influent is very important to ensure the discharge of NH3-N in the effluent. In this test, the influent NH ₃ -N The concentration should be controlled below 150mg/L.

An intermediate water storage tank 20 (as shown in FIG. 4 ) is set between the ultrasonic pretreatment equipment and the biochemical treatment equipment. The water storage tank is also equipped with a heating thermostat 23 to keep the temperature of the waste water at 23-25 degrees Celsius; in addition, a dosing device 22 is attached to continuously supply NaH ₂ PO ₄ to meet the needs of microorganisms for phosphorus; There is a water inlet pipe 24 for domestic sewage (or other carbon sources) to meet the needs of microorganisms for carbon.

Claims (3)

1. ADC foaming agent wastewater treatment method is characterized by the combination of physical and chemical methods and biochemical methods, the former part is physical and chemical methods, ultrasonic pretreatment is used, and the latter part is biochemical methods, based on the DAT-IAT process There is an anoxic pool in front, which forms the anoxic pool-DAT-IAT process, and the front and rear parts are connected by an intermediate water storage tank. 2. The ADC foaming agent wastewater treatment integrated method according to claim 1, characterized in that the intermediate water storage tank is equipped with a heating temperature control device, a dosing device and a water inlet device for domestic sewage. 3. Realize the ADC foaming agent waste water treatment integration device of the method described in claim 1, it is characterized in that: ultrasonic pretreatment equipment mainly is made of four parts of ultrasonic generator, ultrasonic transducer and water tank, aeration device, The biochemical method treatment equipment includes the aerobic-interstitial aeration tank in front of the anoxic tank, which is composed of three parts in series: the anoxic tank, the DAT tank and the IAT tank; the ultrasonic pretreatment equipment and the biochemical treatment equipment are equipped with intermediate storage sink.

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