CN110862185A - Denitrification treatment method for high-concentration nitrate radical wastewater - Google Patents
Denitrification treatment method for high-concentration nitrate radical wastewater Download PDFInfo
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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
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/28—Anaerobic digestion processes
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- 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
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
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- 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
- C02F3/2866—Particular arrangements for anaerobic reactors
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- 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
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- 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
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/16—Nitrogen compounds, e.g. ammonia
- C02F2101/163—Nitrates
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- C02F2201/00—Apparatus for treatment of water, waste water or sewage
- C02F2201/002—Construction details of the apparatus
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/14—Maintenance of water treatment installations
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/16—Regeneration of sorbents, filters
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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
- C02F2305/00—Use of specific compounds during water treatment
- C02F2305/06—Nutrients for stimulating the growth of microorganisms
Abstract
The invention discloses a denitrification treatment method of high-concentration nitrate radical wastewater, which comprises the following steps: step S1, adjusting the pH value of nitrate radical wastewater to 2-4, and then adding a carbon source and nitrogen and phosphorus nutrient salts into the wastewater to obtain pretreated wastewater; step S2, mixing the pretreated wastewater with circulating water, introducing the obtained mixed water into an anoxic fluidized bed reactor to enable the mixed water to be in contact with biological fillers for denitrification reaction, and obtaining denitrification-treated wastewater; wherein, the circulating water is a product obtained by carrying out denitrification reaction on the pretreated wastewater and the biological filler. The method for treating the nitrate radical wastewater has low cost, can continuously treat the wastewater with high concentration of nitrate radical (3000-35000mg/L), and has high treatment efficiency.
Description
Technical Field
The invention relates to a denitrification treatment method for high-concentration nitrate radical wastewater.
Background
With the increasing trend of water eutrophication, especially the increasing discharge amount of nitrate in industrial sewage, the natural circulation of nitrogen is damaged. Nitrate has a plurality of hazards to human health, nitrate enters blood and reacts with hemoglobin to oxidize Fe (II) into Fe (III) to form methemoglobin, and the methemoglobin and oxygen are irreversibly combined to cause methemoglobinemia, and hypoxia death can be caused in severe cases. Therefore, the discharge of nitrate-containing sewage from industrial processes has attracted general attention. In recent years, the sewage discharge standard is increasingly strict, such as the national effluent standard TN (total nitrogen content) of the United states, Canada and the like is less than 3mg/L and TP (phosphorus nitrogen content) is less than 0.18mg/L, so that the nitrate in the treated wastewater is not easy to treat.
Different methods can be adopted for treating high-concentration nitrate wastewater. The graphite electrode is reported to be adopted for electro-adsorption treatment of the nitrate salt water, the removal rate of nitrate nitrogen can reach 52.2 percent, but the method has the defects of high cost and poor nitrate removal capability. In another method, nitrate nitrogen wastewater is treated by a new ion exchange technology and treated by D890 resin, so that nitrate nitrogen in the wastewater can be completely removed, but the industrial production has large amount of nitrate nitrogen wastewater, and the D890 resin is expensive, so that the cost for treating a large amount of wastewater is too high, and the requirement of actual production is difficult to meet. Rivett et al studied the reduction of nitrate in water to ammonia by chemical means under alkaline conditions, in a reaction systemThe catalyst Cu is used, and the result shows that the process is difficult to be practically applied due to high cost. CN106219716A discloses a method for treating high-concentration nitrate wastewater, which adds zinc powder and sulfamic acid into the high-concentration nitrate wastewater for reaction at normal temperature and normal pressure, and the method does not need to additionally purchase wastewater treatment equipment, and NO is generated after wastewater treatment3 -The concentration is less than or equal to 15mg/L, but the defect is that the introduction of zinc powder and the like causes secondary pollution.
In two aspects of thoroughly eliminating nitrate nitrogen pollution in water and reducing denitration cost, the biological denitrification method is the best method which is put into practical use at present, has the characteristics of high efficiency and low consumption, but the activity of denitrifying bacteria is usually inhibited under the condition of high-concentration nitrate radicals by the traditional denitrification technology. Therefore, in view of the current process situation of nitrate removal in water treatment, it is urgently needed to develop a novel enhanced biological denitrification technology, which can improve the treatment load and effectively reduce the operation and maintenance costs while ensuring the removal effect of nitrate and total nitrogen.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a denitrification treatment method for high-concentration nitrate wastewater, which has low cost for treating the nitrate wastewater, can continuously treat the nitrate wastewater with high concentration (3000-.
According to a first aspect of the present invention, there is provided a denitrification treatment method for high-concentration nitrate nitrogen wastewater, comprising:
step S1, adjusting the pH value of the nitrate radical wastewater to 2-4, and adding a carbon source and nitrogen and phosphorus nutrient salts into the wastewater to obtain pretreated wastewater;
step S2, mixing the pretreated wastewater with circulating water, introducing the mixed wastewater into an anoxic fluidized bed device to enable the mixed wastewater to be in contact with biological fillers for denitrification reaction, and obtaining denitrification-treated wastewater;
wherein, the circulating water is a product obtained by carrying out denitrification reaction on the pretreated wastewater and the biological filler.
According to the preferred embodiment of the invention, the concentration of nitrate in the nitrate wastewater is 3000-35000 mg/L.
According to a preferred embodiment of the present invention, in step S1, the pH of the nitrate wastewater is adjusted to 2-4, and then a carbon source and nitrogen and phosphorus nutrient salts are added to the wastewater after the pH adjustment, preferably, the carbon source is added before the nitrogen and phosphorus nutrient salts.
After a period of wastewater treatment, a biofilm grows on the filler, but an excessively thick biofilm can cause adhesion or agglomeration of filler particles, so that local water flow short circuit can be generated. According to a preferred embodiment of the present invention, the method further comprises step S3 of performing an intermittent gas wash on the biological filler; preferably, the time interval of the air washing is 5-100 min/time, and/or the intensity of the air washing is 7-16L/m2S, and/or the time of a single gas wash is 0.5-4 min. The air washing condition set by the invention can realize the quantitative control of the thickness of the biological membrane, thereby not only preventing the recovery time of the biochemical treatment from being overlong caused by excessive stripping, but also preventing the problems of unfavorable mass transfer, aging of the biological membrane and the like caused by excessive thickness of the biological membrane.
According to a preferred embodiment of the present invention, the diameter of the bio-filler is 2.0-2.5mm, and preferably the bio-filler is a polished and degreased bio-filler. The biological filler used in the invention has small particle diameter and large specific surface area, and is easy for the growth of a biological film on the surface of the filler.
According to a preferred embodiment of the present invention, the carbon source is added in step S1 so that the mass concentration ratio of COD to nitrate nitrogen is (3.1-4.7):1, preferably (3.4-4.5):1, and preferably the carbon source is methanol.
According to a preferred embodiment of the invention, nitrogen and phosphorus nutritive salts are added in the step S1 to make the mass concentration of COD, N: P (200- & gt 400) & lt 5:1 & gt, N, P calculated by N, P element respectively, and preferably, the nitrogen nutritive salts are selected from ammonia and/or urea; and/or the phosphorus nutrient salt is selected from KH2PO4And/or Na3PO4。
According to a preferred embodiment of the present invention, the anoxic fluidized bed apparatus comprises a feed tank, a nitrogen purge system and an anoxic fluidized bed reactor;
the nitrogen cleaning system comprises a nitrogen storage tank and a nitrogen outlet distributor, wherein the nitrogen storage tank is connected with the nitrogen outlet distributor through an air inlet pipe;
the anoxic fluidized bed reactor comprises a filler zone, a transition section and a water outlet zone which are sequentially arranged from bottom to top, and a three-phase separator is arranged in the water outlet zone; the bottom of oxygen deficiency fluidized bed is equipped with the water inlet, is equipped with the rivers distributor in the top of water inlet, the below in filler district, and the top periphery in exhalant district is equipped with the overflow weir, is equipped with the delivery port on the upper portion lateral wall in exhalant district, delivery port and overflow weir UNICOM, and the play water of delivery port circulates through the water inlet after circulating pump mixes with the waste water that comes from in the feed tank and returns oxygen deficiency fluidized bed reactor, the filler district is filled with biofilm carrier in, the filler district is arranged in to the nitrogen gas export distributor, prefers the position of nitrogen gas export distributor is adjustable.
According to the preferred embodiment of the present invention, an outlet screen is provided at the water inlet end of the water outlet.
According to a preferred embodiment of the present invention, the anoxic fluidized bed device further comprises an ultrasonic cleaning system, the ultrasonic cleaning system comprises an ultrasonic probe, an ultrasonic heat exchanger and an ultrasonic controller, the ultrasonic probe, the ultrasonic transducer and the ultrasonic controller are sequentially connected, the ultrasonic probe is disposed near a water outlet of the anoxic fluidized bed, and preferably, the ultrasonic probe is disposed outside the water outlet filter screen.
The nitrogen cleaning system is used for intermittently cleaning the filler. According to a preferred embodiment of the present invention, the nitrogen gas cleaning system further comprises a nitrogen gas automatic control device and a gas flow meter, the nitrogen gas automatic control device is connected to the nitrogen gas storage tank, preferably, the nitrogen gas automatic control device comprises a time control system and a gas flow control system, and the nitrogen gas automatic control device controls the flow rate, the ventilation time and the ventilation frequency of the nitrogen gas. The gas of the nitrogen tank is decompressed and then passes through a gas flowmeter, and enters an anoxic fluidized bed through a nitrogen outlet distributor arranged on a filler bed layer, because the attachment of microorganisms on the surface of the filler is influenced by the local energy dispersion rate, the thickness of the filler biofilm is not uniformly distributed in the fluidized bed but is distributed in a step shape from bottom to top, the height of the nitrogen outlet distributor is adjusted according to the requirement of demoulding, the height of the filler layer which needs to be demoulded is controlled, the bubble rubs the biofilm on the filler upwards, the fallen aged biofilm is discharged along with the effluent, and the control on the biomass of the anoxic fluidized bed is realized.
According to the preferred embodiment of the invention, the anoxic fluidized bed device further comprises a heating device, wherein the heating device comprises a reactor jacket, a heater and a heating pump, the reactor jacket is positioned outside the packing region, preferably sleeved at the middle lower part of the packing region, the bottom end of the reactor jacket is provided with a hot water inlet, and the upper end of the reactor jacket is provided with a hot water outlet; the hot water inlet is connected with one end of the heater through the heating pump, and the hot water outlet is connected with the other end of the heater.
According to a preferred embodiment of the present invention, the cross-sectional area of the packing zone is smaller than the cross-sectional area of the effluent zone, preferably the cross-section of the anoxic fluidized bed reactor is circular, and the transition section gradually increases in diameter from bottom to top.
According to a preferred embodiment of the invention, the three-phase separator is arranged in the centre of the outlet zone.
According to a preferred embodiment of the invention, the three-phase separator comprises a central tube and a cover body, the cover body comprises an upper cover body and a lower cover body, and the upper cover body and the lower cover body are connected through a connecting piece and form an overflowing channel; the upper cover body and the lower cover body are in an inverted funnel shape, and the necking end of the upper cover body is connected with the central pipe.
According to a preferred embodiment of the present invention, the water distributor is plate-shaped, and the plate is provided with strip-shaped channels arranged in parallel, preferably, the strip-shaped channels are arranged at equal intervals. The water flow distributor with the structure is beneficial to realizing uniform water distribution.
According to a preferred embodiment of the present invention, the strip-shaped channel is a rectangular channel.
According to a preferred embodiment of the present invention, the width of the channel is smaller than the diameter of the biological filler filled in the filler region, so that the water flow distributor can realize the uniform distribution of water flow at the bottom of the reactor and can also play a role in preventing the biological filler from falling.
The pretreated wastewater is stored in a feeding tank, when the wastewater is treated, the wastewater in the feeding tank is conveyed to a feeding pipe through a feeding pump and is mixed with circulating water flowing out from a water outlet of an anoxic fluidized bed, the concentration of nitrate radical in mixed water obtained by mixing the wastewater in the feeding tank with the circulating water flowing out from the anoxic fluidized bed is reduced to a proper range in a denitrification process, the mixed water enters the anoxic fluidized bed through a water inlet at the bottom of the anoxic fluidized bed, enters a filler zone after being distributed by a water flow distributor, and under the action of upward flowing water flow, granular filler in the fluidized bed floats along with the water flow, and the flow rate of the water flow is controlled to enable the filler in the filler zone to be in a fluidized state. Because the water flow contains biochemically degraded organic matters and nitrate radicals, a microbial film can grow on the filler in the filler area, the denitrification reaction can be realized in the process that the water flow passes through the filler area, nitrogen is generated, and the organic matters and the nitrate radicals in the water flow can be removed. The water flow enters the water outlet zone after passing through the filling zone and the transition section, the cross sectional area of the water outlet zone is larger than that of the filling zone, the rising flow rate of the water flow in the water outlet zone is reduced relative to that in the filling zone, filler particles carried by the water flow in the filling zone are settled in the filling zone after the flow rate of the water flow is reduced, the filler is prevented from being carried out of the fluidized bed, the water flow enters the circulating pump through the water outlet to be the circulating water, and the residual water flows into the drainage pipe discharge system through liquid level height difference overflow.
The water outlet filter screen is connected with the water outlet pipe, the water outlet filter screen is connected with the water outlet pipe.
After a period of wastewater treatment, a biofilm grows on the filler, and an excessively thick biofilm can cause adhesion or agglomeration of filler particles, so that a local water flow short circuit can be generated. The nitrogen cleaning system can clean the biological membrane in time, regulate and control the thickness of the biological membrane in time, maintain high-efficiency matrix mass transfer rate and wastewater treatment efficiency, and prevent the adhesion or agglomeration of filler particles and the formation of local water flow short circuit.
Parameters manipulated during gas stripping include: (1) gas parameters: the air-wash frequency, the air-wash intensity, the air-wash time and the position of the gas distributor; (2) liquid parameters: increasing the flow rate and washing strength; (3) matrix loading: feed concentration and feed loading.
The technological process of the anoxic fluidized bed gas scrubbing and stripping comprises the following steps: when the biomembrane growing on the filler is too thick and influences the matrix mass transfer rate and the treatment effect of the reactor, the gas automatic control device controls the nitrogen storage tank to be started to generate nitrogen, the nitrogen flows through the gas flowmeter, enters the nitrogen outlet distributor through the gas inlet pipe and enters the anoxic fluidized bed, bubbles upwards rub the biomembrane on the filler, after a period of time, the biomembrane on the filler particles is removed, and the gas automatic control device stops supplying gas. The position of the nitrogen outlet distributor can be controlled by vertically adjusting the position of the air inlet pipe, so that accurate backwashing of the filler in the filler layers with different heights is realized, the stripping amount is well tracked, and the utilization rate of gas washing is effectively improved.
The gas automatic control device comprises a time control system and a gas flow control system, wherein the time control system can control the length and the time interval of ventilation time to realize the adjustment of gas frequency, and the gas flow control system can realize the regulation and control of gas strength. The time interval of air washing is set to be 5-100 min/time, and/or the intensity of the air washing is 7-16L/m2S, and/or the time of each air-wash is 0.5-4 min. The inventionCan realize the quantitative control of the thickness of the biological membrane, not only can prevent the long recovery time of biochemical treatment caused by excessive demoulding, but also can prevent the problems of unfavorable mass transfer, aging of the biological membrane and the like caused by excessive thickness of the biological membrane.
In the invention, the wastewater and the mixed water are mixed and then are introduced into the anoxic fluidized bed, because the denitrification reaction is an alkali-producing reaction, and the pH value of the mixed circulating water and the pretreated wastewater can reach the proper range in the denitrification process, the consumption of neutralizing alkali can be reduced in the pretreatment process.
The gas automatic control device of the invention adjusts the gas washing condition to realize the timely regulation and control of the thickness of the biological membrane, and in addition, the position of the nitrogen outlet distributor can be adjusted according to the requirement, the oriented positioning and accurate membrane removal can be realized, and the membrane removal amount can be effectively tracked.
The packed bed used in the invention is in a fluidized state during normal operation, and the flow state of solid and liquid phases is beneficial to the contact and mass transfer of microorganisms and sewage, thereby improving the biological reaction efficiency; the structural design of the water flow distributor can realize uniform water distribution, and the forced circulation of water flow can treat high-concentration nitrate radical wastewater, thereby improving the stability and impact resistance of the biological reaction process; the ultrasonic cleaning system cleans the water outlet filter screen, realizes continuous sludge discharge of the device water outlet, and solves the problem of filler blockage.
Drawings
FIG. 1 is a schematic view of an anoxic fluidized bed apparatus;
FIG. 2 is a schematic diagram of a three-phase separator configuration;
FIG. 3 is a schematic view of a water distributor configuration;
the system comprises a feeding tank, a feeding pump, a water inlet, a water flow distributor, a filling area, a water outlet area, a water collecting tank, a water outlet weir, a water outlet, a three-phase separator, a water collecting tank, a water outlet weir, a water outlet, a three-phase separator, a sludge discharge port, a hot water inlet, a hot water outlet, a heater, a heating pump, a circulating pump, a water outlet 17, an ultrasonic probe, an ultrasonic transducer, a nitrogen storage tank, an ultrasonic controller, a nitrogen outlet filter screen, a gas flowmeter, a nitrogen storage tank, a gas automatic control device, a nitrogen outlet distributor, a transition section, a nitrogen storage tank, a; 10-a, a central pipe, 10-b, an upper cover body, 10-c, a lower cover body, 10-d and a connecting piece.
Detailed Description
The present invention will be described in detail with reference to examples, but the present invention is not limited to the examples.
The invention provides a denitrification treatment method of high-concentration nitrate wastewater, and the structure of an anoxic fluidized bed device used in the embodiment of the invention is as follows: as shown in figures 1-3, the anoxic fluidized bed device for denitrification treatment of nitrate nitrogen wastewater of the invention comprises a feeding tank, a nitrogen cleaning system, an ultrasonic cleaning system, a heating device and an anoxic fluidized bed reactor,
the nitrogen cleaning system comprises a nitrogen storage tank 22, a nitrogen outlet distributor 24, a nitrogen automatic control device 23 and a gas flowmeter 21, wherein the nitrogen storage tank 22 is connected with the nitrogen outlet distributor 24 through an air inlet pipe, the gas flowmeter is arranged on the air inlet pipe, the nitrogen automatic control device 23 is connected with the nitrogen storage tank 22, the nitrogen automatic control device comprises a time control system and a gas flow control system, and the nitrogen automatic control device controls the flow, the ventilation time and the ventilation frequency of nitrogen.
The anoxic fluidized bed reactor comprises a filler zone 5, a transition section and a water outlet zone 6 which are arranged from bottom to top in sequence, and a three-phase separator 10 is arranged at the central position of the water outlet zone 6; the anaerobic fluidized bed is characterized in that a water inlet 3 is formed in the bottom end of the anaerobic fluidized bed, a water flow distributor 4 is arranged above the water inlet 3 and below the packing area 5, a water collecting tank 7 and a water outlet weir 8 are arranged on the periphery of the top of the water outlet area 6, a water outlet 9 is formed in the side wall of the upper portion of the water outlet area 6, the water outlet 9 is communicated with the water outlet weir 8, effluent of the water outlet 9 flows through a circulating pump 16 and is mixed with wastewater from the feeding tank 1 and then circulates back to the anaerobic fluidized bed reactor through the water inlet 3, biological packing is filled in the packing area 5, the particle size of the biological packing is 2.0-2.5mm, a nitrogen outlet distributor 24 is arranged in the packing area 5, and the position. And a water outlet filter screen 20 is arranged at the water inlet end of the water outlet. The ultrasonic cleaning system comprises an ultrasonic probe 17, an ultrasonic heat exchanger 18 and an ultrasonic controller 19, wherein the ultrasonic probe 17, the ultrasonic transducer 18 and the ultrasonic controller 19 are sequentially connected, the ultrasonic probe 17 is arranged near a water outlet of the anoxic fluidized bed, and preferably, the ultrasonic probe 17 is arranged on the outer side of the water outlet filter screen 20.
The heating device comprises a reactor jacket, a heater 14 and a heating pump 15, the reactor jacket is positioned outside the packing area, preferably sleeved outside the lower half part of the packing area, the bottom end of the reactor jacket is provided with a hot water inlet 12, and the upper end of the reactor jacket is provided with a hot water outlet 13; the hot water inlet is connected with one end of the heater through the heating pump, and the hot water outlet is connected with the other end of the heater.
The cross-sectional area of the filling zone is smaller than that of the water outlet zone, the cross section of the anoxic fluidized bed reactor is circular, and the diameter of the transition section is gradually increased from bottom to top. The anoxic fluidized bed reactor is vertically arranged, namely the plane of the cross section of the anoxic fluidized bed is parallel to the arranged plane.
The three-phase separator comprises a central tube 10-a and a cover body, the cover body comprises an upper cover body 10-b and a lower cover body 10-c, and the upper cover body 10-b and the lower cover body 10-c are connected through a connecting piece 10-d and form an overflowing channel; the upper cover body 10-b and the lower cover body 10-c are in an inverted funnel shape, and the necking end of the upper cover body is connected with the central pipe.
The water flow distributor is plate-shaped, and strip-shaped channels which are arranged in parallel are arranged on the plate, preferably, the strip-shaped channels are arranged at equal intervals. Preferably, the strip-shaped channel is a rectangular channel. The width of the channel is smaller than the diameter of the biological filler filled in the filler area, so that the water flow distributor can realize the uniform distribution of water flow at the bottom of the reactor and can also play a role in preventing the biological filler from falling.
The wastewater treatment process comprises the following steps of firstly pretreating wastewater, wherein the wastewater pretreatment comprises the steps of adjusting the pH value of the wastewater containing nitrate radicals to 2-4, then adding a carbon source and nitrogen and phosphorus nutrient salts into the wastewater to obtain pretreated wastewater, then storing the pretreated wastewater in a feeding tank, introducing the pretreated wastewater into an anoxic fluidized bed when the denitrification reaction is started, and enabling water flow to enter a water outlet region after passing through a filler region and a transition section and flow out of a water outlet to enter a circulating pipeline, so that the anoxic fluidized bed reactor is started. The pretreated wastewater and the filler are subjected to contact reaction to obtain water, the water flows out from a water outlet to form circulating water, the circulating water is mixed with the wastewater from a feeding tank, the concentration of nitrate radicals in the mixed water obtained after the wastewater in the feeding tank is mixed with the circulating water flowing out from the anoxic fluidized bed is reduced to a proper range in a denitrification process, the mixed water enters the anoxic fluidized bed through a water inlet at the bottom of the anoxic fluidized bed, is distributed by a water flow distributor and then enters a filler area, under the action of upward flowing water flow, the granular filler in the fluidized bed floats with the water flow, and the flow rate of the water flow is controlled to enable the filler in the filler area to be in a fluidized state. Because the water flow contains biochemically degraded organic matters and nitrate radicals, a microbial film can grow on the filler in the filler area, the denitrification reaction can be realized in the process that the water flow passes through the filler area, nitrogen is generated, and the organic matters and the nitrate radicals in the water flow can be removed. The water flow enters the water outlet zone after passing through the filling zone and the transition section, the cross sectional area of the water outlet zone is larger than that of the filling zone, the rising flow rate of the water flow in the water outlet zone is reduced relative to that in the filling zone, filler particles carried by the water flow in the filling zone are settled in the filling zone after the flow rate of the water flow is reduced, the filler is prevented from being carried out of the fluidized bed, the water flow enters the circulating pump through the water outlet to be the circulating water, and the residual water flows into the drainage pipe discharge system through liquid level height difference overflow.
The water outlet filter screen is connected with the water outlet pipe, the water outlet filter screen is connected with the water outlet pipe.
After a period of wastewater treatment, a biofilm grows on the filler, and an excessively thick biofilm can cause adhesion or agglomeration of filler particles, so that a local water flow short circuit can be generated. The nitrogen cleaning system can clean the biological membrane in time, regulate and control the thickness of the biological membrane in time, maintain high-efficiency matrix mass transfer rate and wastewater treatment efficiency, and prevent the adhesion or agglomeration of filler particles and the formation of local water flow short circuit.
Parameters manipulated during gas stripping include: (1) gas parameters: the air-wash frequency, the air-wash intensity, the air-wash time and the position of the gas distributor; (2) liquid parameters: increasing the flow rate and washing strength; (3) matrix loading: feed concentration and feed loading.
The technological process of the anoxic fluidized bed gas scrubbing and stripping comprises the following steps: when the biomembrane growing on the filler is too thick and influences the matrix mass transfer rate and the treatment effect of the reactor, the gas automatic control device controls the nitrogen storage tank to be started to generate nitrogen, the nitrogen flows through the gas flowmeter, enters the nitrogen outlet distributor through the gas inlet pipe and enters the anoxic fluidized bed, bubbles upwards rub the biomembrane on the filler, after a period of time, the biomembrane on the filler particles is removed, and the gas automatic control device stops supplying gas. The position of the nitrogen outlet distributor can be controlled by vertically adjusting the position of the air inlet pipe, so that accurate backwashing of the filler in the filler layers with different heights is realized, the stripping amount is well tracked, and the utilization rate of gas washing is effectively improved.
The gas automatic control device comprises a time control system and a gas flow control system, wherein the time control system can control the length and the time interval of ventilation time to realize the adjustment of gas frequency, and the gas flow control system can realize the regulation and control of gas strength. The time interval of air washing is set to be 5-100 min/time, and/or the intensity of the air washing is 7-16L/m2S, and/or the time of each air-wash is 0.5-4 min. Can realize the quantitative control of the thickness of the biological membrane, not only can prevent the long recovery time of biochemical treatment caused by excessive demoulding, but also can prevent the problems of unfavorable mass transfer, aging of the biological membrane and the like caused by excessive thickness of the biological membrane.
Example 1
The industrial wastewater treated in this example had a nitrate concentration of 14344mg/L (NO)3 -N concentration was 3238mg/L), COD concentration was 2600mg/L, and pH was 0.2.
Firstly, the industrial wastewater is pretreated, comprising the following steps:
(1) adding alkali (NaOH) into industrial wastewater to adjust the pH of inlet water to 2;
(2) adding supplementary methanol into the wastewater with the pH adjusted in the step (1) to ensure that COD is 12410mg/L and COD is NO3 -The mass concentration ratio of N is 3.8;
(3) adding nitrogen nutrient salt (ammonia water or urea) and phosphorus nutrient salt (KH) into the wastewater obtained in the step (2)2PO4Or Na3PO4) Respectively, the concentration of N is 205mg/L calculated by N element, the concentration of P is 41mg/L calculated by P element, and the mass concentration ratio of COD to N to P is 302:5: 1; obtaining the pretreated wastewater.
(4) Introducing the pretreated wastewater into an anoxic fluidized bed reactor at a certain flow rate, carrying out contact reaction on the wastewater and a filler in an anoxic fluidized bed, flowing through a filler region, a transition section and a water outlet region, flowing out of a water outlet, flowing through a circulating pump, mixing with the pretreated wastewater from a feed pipe, allowing the mixed water to enter the anoxic fluidized bed from a water inlet, and allowing the mixed water to enter the filler region, the transition section and the water outlet region after being distributed by a water flow distributor. Because the water flow contains biochemically degraded organic matters and nitrate radicals, a microbial film can grow on the filler in the filler area, the denitrification reaction can be realized in the process that the water flow passes through the filler area, nitrogen is generated, and the organic matters and the nitrate radicals in the water flow can be removed. Water flow enters the circulating pump through the water outlet, and residual water flows into the drain pipe discharge system through liquid level difference overflow.
The nitrogen automatic control device controls the cleaning to be carried out once at intervals of 18min, and the strength of the gas washing is 10.5L/m2S, the time of a single air wash is 0.8-1.8 min.
The volume load (calculated according to the inflow water) of the nitrate radical in the wastewater can be up to 11.5 kg/(m)3D) the highest capacity load of treating nitrate radical in the wastewater can reach 10.9 kg/(m) calculated according to inlet and outlet water3D) nitrate nitrogen energy in the treated waterThe removal rate of nitrate nitrogen is reduced to be below 32mg/L from 3238mg/L, the removal rate of nitrate nitrogen reaches over 99 percent, and the removal rate of methanol reaches 96 percent.
Example 2
The nitrate content of the industrial wastewater treated in the example is 30443mg/L (NO)3 -N concentration is 6874mg/L), COD concentration is 5700mg/L, and pH is 0.4.
Firstly, the industrial wastewater is pretreated, comprising the following steps:
(1) adding alkali (NaOH) into the wastewater to adjust the pH of the inlet water to 2.3;
(2) adding a supplementary carbon source (methanol) into the wastewater after the pH is adjusted in the step (1) to ensure that the COD is 24059mg/L and the COD is NO3 -The mass concentration ratio of N is 3.5;
(3) adding nitrogen nutrient salt (ammonia water or urea) and phosphorus nutrient salt (KH) into the wastewater obtained in the step (2)2PO4Or Na3PO4) Respectively, the concentration of N is 301mg/L calculated by N element, the concentration of P is 60mg/L calculated by P element, and the mass concentration ratio of COD to N to P is 400:5:1, thus obtaining pretreated wastewater;
(4) introducing the pretreated wastewater into an anoxic fluidized bed reactor at a certain flow rate, carrying out contact reaction on the wastewater and a filler in an anoxic fluidized bed, flowing through a filler region, a transition section and a water outlet region, flowing out of a water outlet, flowing through a circulating pump, mixing with the pretreated wastewater from a feed pipe, allowing the mixed water to enter the anoxic fluidized bed from a water inlet, and allowing the mixed water to enter the filler region, the transition section and the water outlet region after being distributed by a water flow distributor. Because the water flow contains biochemically degraded organic matters and nitrate radicals, a microbial film can grow on the filler in the filler area, the denitrification reaction can be realized in the process that the water flow passes through the filler area, nitrogen is generated, and the organic matters and the nitrate radicals in the water flow can be removed. Water flow enters the circulating pump through the water outlet, and residual water flows into the drain pipe discharge system through liquid level difference overflow.
The nitrogen automatic control device controls the cleaning to be carried out once every 12min, and the strength of the gas washing is 10.4L/m2S, the time of single air washing is 1.6-3.0 min.
This example enables the treatment of the volume load of nitrate in wastewater (calculated as influent water)) The maximum value can reach 12.1 kg/(m)3D) the highest capacity load of treating nitrate radical in the wastewater can reach 11.8 kg/(m) calculated according to inlet and outlet water3D), the nitrate nitrogen in the treated water can be reduced from 6874mg/L to 102mg/L, the removal rate of nitrate nitrogen reaches more than 98 percent, and the removal rate of methanol reaches 97 percent.
It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.
Claims (10)
1. A denitrification treatment method for high-concentration nitrate nitrogen wastewater comprises the following steps:
step S1, adjusting the pH value of nitrate radical wastewater to 2-4, and then adding a carbon source and nitrogen and phosphorus nutrient salts into the wastewater to obtain pretreated wastewater;
step S2, mixing the pretreated wastewater with circulating water, introducing the obtained mixed water into an anoxic fluidized bed device to enable the mixed water to be in contact with biological fillers for denitrification reaction, and obtaining denitrification-treated wastewater;
wherein, the circulating water is a product obtained by carrying out denitrification reaction on the pretreated wastewater and the biological filler.
2. The method as claimed in claim 1, wherein the concentration of nitrate in the nitrate wastewater is 3000-35000 mg/L.
3. The method according to claim 1 or 2, further comprising step S3, performing an intermittent gas wash on the biological filler; preference is given toThe time interval of the air washing is 5-100 min/time, and/or the intensity of the air washing is 7-16L/m2S, and/or the time of each air-wash is 0.5-4 min.
4. A method according to any one of claims 1-3, characterized in that the diameter of the biological filler is 2.0-2.5mm, preferably the biological filler is a polished and degreased biological filler.
5. The method according to any one of claims 1 to 4, wherein the carbon source is added in step S1 so that the mass concentration ratio of COD to nitrate nitrogen is (3.1-4.7):1, preferably (3.4-4.5):1, and preferably the carbon source is methanol.
6. The method according to any one of claims 1 to 5, wherein the step S1 is followed by the addition of nitrogen and phosphorus nutritive salts, preferably wherein the step S1 comprises the addition of nitrogen and phosphorus nutritive salts in a mass concentration ratio such that the COD: N: P is (200-) (400): 5:1, N, P in a mass concentration ratio of N, P elements, preferably wherein the nitrogen nutritive salts are selected from ammonia and/or urea; and/or, the phosphorus nutrient salt is selected from KH2PO4And/or Na3PO4。
7. The method of any one of claims 1-6, the anoxic fluidized bed apparatus comprising a feed tank, a nitrogen purge system, and an anoxic fluidized bed reactor,
the nitrogen cleaning system comprises a nitrogen storage tank and a nitrogen outlet distributor, wherein the nitrogen storage tank is connected with the nitrogen outlet distributor through an air inlet pipe;
the anoxic fluidized bed reactor comprises a filler zone, a transition section and a water outlet zone which are sequentially arranged from bottom to top, and a three-phase separator is arranged in the water outlet zone; the bottom of oxygen deficiency fluidized bed is equipped with the water inlet, is equipped with the rivers distributor in the top of water inlet, the below in filler district, and the top periphery in exhalant district is equipped with the overflow weir, is equipped with the delivery port on the upper portion lateral wall in exhalant district, delivery port and overflow weir UNICOM, and the play water of delivery port circulates through the water inlet after circulating pump mixes with the waste water that comes from in the feed tank and returns oxygen deficiency fluidized bed reactor, the filler district is filled with biofilm carrier in, the filler district is arranged in to the nitrogen gas export distributor, prefers the position of nitrogen gas export distributor is adjustable.
8. The method of claim 7, wherein an outlet screen is provided at the inlet end of the outlet; preferably, the anoxic fluidized bed device further comprises an ultrasonic cleaning system, the ultrasonic cleaning system comprises an ultrasonic probe, an ultrasonic heat exchanger and an ultrasonic controller, the ultrasonic probe, the ultrasonic heat exchanger and the ultrasonic controller are sequentially connected, the ultrasonic probe is arranged near a water outlet of the anoxic fluidized bed, and preferably, the ultrasonic probe is arranged on the outer side of the water outlet filter screen.
9. The method of claim 7 or 8, wherein the nitrogen purging system further comprises a nitrogen automatic control device and a gas flow meter, the nitrogen automatic control device is connected with the nitrogen storage tank, preferably the nitrogen automatic control device comprises a time control system and a gas flow control system, and the nitrogen automatic control device controls the flow rate, the ventilation time and the ventilation frequency of the nitrogen.
10. The method according to any one of claims 7 to 9, wherein the anoxic fluidized bed device further comprises a heating device, the heating device comprises a reactor jacket, a heater and a heating pump, the reactor jacket is positioned outside the packing region, preferably is sleeved at the middle lower part of the packing region, the bottom end of the reactor jacket is provided with a hot water inlet, and the upper end of the reactor jacket is provided with a hot water outlet; the hot water inlet is connected with one end of the heater through the heating pump, and the hot water outlet is connected with the other end of the heater;
preferably, the cross-sectional area of the packing zone is smaller than that of the water outlet zone, preferably, the cross-section of the anoxic fluidized bed reactor is circular, and the diameter of the transition section is gradually increased from bottom to top.
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