CN105600927A - Wastewater simultaneous nitrification and denitrification denitrifying method and device - Google Patents

Abstract

The invention discloses a waste water synchronous nitrification denitrification denitrification device and a waste water synchronous nitrification denitrification denitrification method. The bioreactor used in the device and method is provided with a partition in the space of the reaction tank, the top of the partition is used as an overflow port, the bottom of the partition is connected, and both sides of the partition form an ascending channel and a descending channel, thereby forming a circulation channel. An aeration system is installed at the bottom of the ascending channel. The incoming wastewater is aerated and mixed for nitrification. At least part of the wastewater descends along the descending channel through the overflow. Basalt fiber filler is installed in the descending channel. A large number of microorganisms in the wastewater are easy to adhere to the basalt. The growth on the fiber makes the nitrifying bacteria and denitrifying bacteria enriched on the basalt fiber, and the descending wastewater reaches the bottom of the reaction tank and then aerated and mixed, and enters the ascending channel through the bottom of the clapboard, so as to perform high-speed circulation treatment. The device and method of the invention realize the synchronous treatment of nitrification and denitrification in the same reaction pool.

Description

Method and device for synchronous nitrification and denitrification denitrification of wastewater

technical field

The invention belongs to the technical field of wastewater treatment, and in particular relates to a wastewater synchronous nitrification and denitrification denitrification method and device.

Background technique

With the rapid development of the economy, the amount of wastewater discharged by industries such as chemical industry, printing and dyeing, and medicine is increasing, and the water quality is becoming more and more complicated. Especially for some large fermentation pharmaceutical companies in China, the wastewater generated during production contains fermentation residual culture medium, mycelium and various complex metabolites produced during the fermentation process, such as carbohydrates, proteins, and organic acids; There are also organic solvents, acids and bases, sulfates and a small amount of antibiotics produced during the extraction process. Because it contains biodegradable organic substances produced by biological fermentation and metabolism, and a small amount of antibiotics that are toxic and inhibitory to microorganisms, it has high chroma, complex components, and large changes in water quality and quantity. It is a kind of high-concentration organic wastewater that is difficult to treat. It is extremely difficult to achieve the treatment effect of this kind of wastewater by combining general physical and chemical pretreatment with biochemical treatment or only biochemical treatment. It is urgent to develop economical and effective aureomycin wastewater treatment technology.

Biological denitrification is a relatively mature and reliable method, and the microorganisms responsible for denitrification are mainly nitrifying bacteria and denitrifying bacteria. In practical engineering applications, the growth environments of the two types of bacteria are completely different, so the nitrification and denitrification processes are generally separated. Good, the sewage treatment equipment occupies a large area, and the investment and operation costs are high.

In recent years, researchers at home and abroad have gradually mixed cultured nitrifying bacteria and denitrifying bacteria in the same reactor, and carried out nitrification and denitrification reactions simultaneously. Cost saving, so the simultaneous nitrification and denitrification denitrification process has become a hot spot in the field of sewage treatment. But the result of this process is not satisfactory, and the actual engineering application has yet to be verified. Some related research work has been carried out in China. The patent CN102050521B discloses a method for synchronous nitrification and denitrification treatment of ammonia-containing sewage. Ammonia sewage. This method has a high removal rate of organic pollutants, but this method needs to domesticate and cultivate nitrifying granular sludge first, separate and screen aerobic denitrifying bacteria, and then mix the two to prepare denitrifying granular sludge. The actual operation process in the early stage It is more complicated, and there is a problem of amplification in practical engineering applications. Patent CN104609565A discloses a simultaneous nitrification and denitrification treatment method for ammonia-containing wastewater. In this method, a separation membrane needs to be installed to carry out nitrification and denitrification partition reactions, which can ensure the effective occurrence of nitrification and denitrification reactions respectively. However, after a long period of operation, The separation membrane is easily blocked by suspended matter, which affects the effect.

Although the synchronous nitrification and denitrification denitrification technology has made great breakthroughs, it still has the disadvantages of low removal rate and unstable operation, and there are no relevant case reports for the denitrification of high-concentration pharmaceutical wastewater, and most of the existing All the processes are only effective for the removal of ammonia nitrogen, but the removal of total nitrogen is still not ideal, which seriously limits the practical application of this process. Therefore, it is very important to take simple and effective measures to ensure that nitrification and denitrification can be carried out synchronously, efficiently and stably for a long time, which is very important for the engineering application of this process.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the prior art, and provide a wastewater treatment device and method for simultaneous nitrification and denitrification.

Specifically, the present invention adopts the following technical solutions:

A device for synchronous nitrification and denitrification of wastewater, including a bioreactor, characterized in that a partition is set in the reaction pool space in the bioreactor, the top of the partition is used as an overflow port, the bottom of the partition is connected, and the bottom of the partition is connected. The reaction tank space on both sides forms an ascending channel and a descending channel respectively, thereby forming a circulation channel in the bioreactor, wherein an aeration system is set at the bottom of the ascending channel, and the wastewater inlet is set at the bottom of the ascending channel, and the incoming wastewater is aerated and The water from the descending channel is mixed to carry out efficient nitrification reaction. Part of the wastewater in the ascending channel descends along the descending channel through the overflow port, and part of it flows out through the water outlet set on the top of the descending channel of the reaction pool; basalt fiber filler is set in the descending channel. The packing is fully submerged in the waste water. The basalt fiber filler is composed of fiber bundles, which are composed of basalt fiber monofilaments with a certain diameter. A large number of microorganisms in the wastewater are easy to adhere to the basalt fibers to grow and reproduce, so that the nitrifying bacteria and denitrifying bacteria can be enriched on the basalt fibers. The waste water in the descending channel reaches the bottom of the reaction tank, and the bottom of the clapboard and the influent at the bottom of the ascending channel are fully mixed and risen to perform high-speed circulation treatment.

In the above device, the basalt fiber filler is formed by hanging fiber bundles vertically, or by arranging fiber bundles around a fixed core material.

Preferably, the basalt fiber filler is fixed on the side of the descending channel on the separator.

The invention also discloses a wastewater synchronous nitrification and denitrification denitrification method, which is characterized in that the method includes transporting the wastewater into the reaction pool of the bioreactor, wherein a partition is set in the space of the reaction pool, and the partition The upper end is used as an overflow port, the bottom of the partition is connected, and the reaction tank space on both sides of the partition forms an ascending channel and a descending channel, thereby forming a circulation channel in the bioreactor; an aeration system is set at the bottom of the ascending channel, and the waste water inlet Set at the bottom of the ascending channel, the wastewater entering through the water inlet is fully mixed with the incoming water of the descending channel through aeration to carry out efficient nitrification reaction. The descending channel descends, and part of it flows out through the water outlet arranged on the top of the descending channel of the reaction pool; basalt fiber packing is suspended in the descending channel, and the packing is completely submerged in the waste water. The basalt fiber filler is composed of fiber bundles, which are composed of basalt fiber monofilaments with a certain diameter. A large number of microorganisms in the wastewater are easy to adhere to the basalt fibers to grow and reproduce, so that the nitrifying bacteria and denitrifying bacteria can be enriched on the basalt fibers. The descending wastewater passes through the basalt fiber enriched with nitrifying bacteria and denitrifying bacteria, and undergoes nitrification and denitrification reactions at the same time; the wastewater reaches the bottom of the reaction tank after simultaneous nitrification and denitrification treatment, and is fully mixed with the influent at the bottom of the ascending channel Rise to perform high-speed cycle processing.

In the above devices and methods, preferably, the single filament diameter of the basalt fiber filler is 10-20 μm.

Preferably, during the aeration process, the dissolved oxygen concentration in the aeration zone of the reactor is controlled by the aeration system to be 1.0-5.0 mg/L.

In another preferred solution, the reaction temperature of the reactor is controlled to be 20-35° C., and the pH value is 6-9.

On the other hand, the concentration of free sludge in the reactor is controlled to be 2.0~6.0g/L, and the sludge concentration in the reactor is guaranteed to be stable by setting the sludge return flow in the sedimentation tank, and the sludge return ratio is controlled to be 50% ~100%.

As a preferred embodiment, the concentration of ammonia nitrogen in the wastewater to be treated is 280-470 mg/L, the concentration of total nitrogen is 400-650 mg/L, and the concentration of COD is 2000-3000 mg/L.

Also preferably, the required organic carbon source is added according to the carbon-to-nitrogen mass ratio of 4:1-10:1, and the organic carbon source is one of methanol, ethanol, sodium acetate, glucose, flour, and the like.

Compared with the prior art, the present invention has the following prominent features:

1. The basalt fiber is set in the reactor, the activated sludge is easy to adhere to the basalt fiber, and the sludge on the fiber accumulates for a long time. The aeration device is set in the reactor to make the surface of the sludge in an aerobic state, and a large number of nitrifying bacteria gather , The inside of the sludge is anaerobic or anoxic due to insufficient oxygen supply, and denitrifying bacteria are enriched. Therefore, by controlling the appropriate amount of dissolved oxygen, the nitrification reaction and denitrification reaction are simultaneously carried out in the reactor, that is, simultaneous nitrification and denitrification reaction. Nitrifying bacteria use ammonia nitrogen in wastewater to carry out nitrification reaction, and the produced nitrate nitrogen or nitrite nitrogen can enter the sludge interior as nutrients for denitrifying bacteria, and convert nitrate nitrogen or nitrite nitrogen into nitrogen gas. Due to the reduction of product inhibition, it helps to improve the effect of nitrification reaction, and nitrification and denitrification promote each other to achieve efficient removal of total nitrogen. Therefore, compared with the traditional denitrification process, nitrification and denitrification can be carried out in the same reactor, which reduces the complexity of separate nitrification tanks and denitrification tanks, reduces the equipment footprint, and saves investment. cost. In addition, synchronous nitrification and denitrification can significantly shorten the hydraulic retention time, improve the efficiency of sewage treatment, and greatly improve the operating efficiency of the device.

2. The alkalinity will be consumed when the nitrification reaction occurs, so it is usually necessary to add lye to maintain an environment suitable for the growth of nitrifying bacteria, and when the nitrification and denitrification are carried out simultaneously in one reactor, the denitrification reaction will generate alkalinity to make up for part of the nitrification reaction The required alkalinity reduces the consumption of additional lye and saves operating costs.

3. The fiber material filled in the reactor is in bundle shape, and the contact area with the sewage is large. For general wastewater, in addition to ammonia nitrogen, it also contains other suspended substances that are difficult to degrade. These substances that are difficult to remove by conventional biochemical methods may be adsorbed and fixed on basalt fibers with the circulation of wastewater, which can reduce the residual to a certain extent. The amount of sludge produced.

4. The reactor is equipped with baffles, the two ends of the basalt fiber are fixed, the bottom of the baffle is connected, and the upper end is used as an overflow port. The sewage enters the reactor and is fully mixed under the action of aeration. The sewage descends along the channel, that is, it circulates rapidly in the reaction tank. The particle size of the activated sludge is larger than that obtained in the conventional nitrification tank. The viscosity of the sewage in the reactor will not increase with the increase of the sludge concentration. And excessive increase, so that dissolved oxygen can be effectively used. In addition, this high-speed flow not only ensures the high efficiency of nitrification reaction, but also causes the swaying of basalt fibers. When the microbial load of basalt fibers is too high, the sludge enriched in nitrifying bacteria on the surface part falls off and enters the reactor for aeration. In the area, the number of nitrifying bacteria increases, thereby improving the nitrification reaction efficiency in the aeration area.

Description of drawings

Fig. 1 is a structural schematic diagram of a wastewater synchronous nitrification and denitrification denitrification reactor device of the present invention.

Fig. 2 is a structure of basalt fiber bundles in the wastewater synchronous nitrification and denitrification denitrification reactor of the present invention.

Fig. 3 is a cross-sectional schematic view of the formation of nitrifying and denitrifying bacterial films on basalt fibers.

In the figure: 1-bioreactor; 2-basalt fiber; 3-aeration area; 4-filling area descending channel; 5-aeration system; 6-water inlet; Source port; 9-water outlet; 10-baffle; 11-core material; 12-basalt fiber bundle; 13-basalt fiber; 14-anoxic zone; 15-aerobic zone.

detailed description

The present invention provides a new method and device for synchronous nitrification and denitrification of wastewater, using basalt fiber filler to form aerobic zone and anoxic zone from the outside to the inside of the cross section, and efficiently remove the nitrogen in the wastewater. The total nitrogen index in the waste water is better than the requirement of the water pollutant discharge standard of the fermentation pharmaceutical industry, and the nitrification and denitrification reaction in the same reaction tank is realized, thereby overcoming the shortcomings in the prior art. The technology of the present invention is especially suitable for wastewater treatment of fermented pharmaceutical enterprises, especially for wastewater denitrification treatment in the production process of chlortetracycline.

The waste water synchronous nitrification and denitrification denitrification device of the present invention comprises the following contents: a basalt fiber is fixed at both ends of the basalt fiber in the aeration bioreactor, the bottom end of the baffle plate is connected, and the upper end is used as an overflow port, and the basalt fiber is completely immersed in the In the wastewater, an aeration system is installed at the bottom of the reaction tank, and the wastewater enters the reactor continuously at a certain flow rate, and the aeration is mixed to carry out the nitrification reaction. Part of the wastewater descends along the channel through the overflow port, and a large number of microorganisms in the wastewater are easy to adhere to the basalt fiber. Growth, especially the enrichment of a large number of nitrifying bacteria and denitrifying bacteria, the descending wastewater reaches the bottom of the device, is aerated and mixed, then flows upward through the ascending channel, overflows through the baffle, part of the water is discharged, and part of it enters the descending channel, so that the high-speed Loop processing.

In the present invention, the basalt fibers used are vertically suspended or spirally wrapped around the fixed core material.

In the present invention, an aeration system is used to control the dissolved oxygen concentration in the aeration area of the reactor to be 1.0-5.0 mg/L, preferably 2.0-4.0 mg/L. The aeration device is set in a biased direction. With the flow of sewage, oxygen is effectively used in the reactor, and relatively little oxygen enters the packing-intensive area, which is conducive to the formation of an anoxic or anoxic environment for efficient denitrification. When the dissolved oxygen concentration deviates greatly, the appropriate dissolved oxygen concentration is controlled by adjusting the aeration rate. In addition, the temperature of the reaction system is controlled at 20-35°C, and the pH range of 6-9 is achieved by adding acid and alkali.

In the present invention, ordinary activated sludge is selected as the sludge. In the actual wastewater treatment process, the free sludge concentration in the reactor is controlled to be 2.0~6.0g/L, and the sewage in the reactor is guaranteed by setting the sedimentation tank sludge backflow mode. To stabilize the sludge concentration, control the sludge return ratio range from 50% to 100%.

In the present invention, the wastewater to be treated is mainly aureomycin wastewater, the ammonia nitrogen concentration is generally 280~470mg/L, the total nitrogen concentration is generally 400~650mg/L, and the COD concentration is generally 2000~3000mg/L; Or the way of continuous water inflow, when adopting continuous water inflow for biological denitrification treatment, the hydraulic retention time is generally 8 to 12 hours.

In the present invention, for supplementing the carbon source, the required organic carbon source is added according to the carbon-to-nitrogen mass ratio of 4:1 to 10:1, and the organic carbon source is one of methanol, ethanol, sodium acetate, glucose, flour, etc. Or two; use batch or continuous addition to supplement the organic carbon source.

The present invention will be described further with reference to the accompanying drawings.

The process of realizing synchronous nitrification and denitrification denitrification by using basalt fiber in the present invention is shown in Fig. 1 . A partition 10 is arranged in the aerated bioreactor 1 , and basalt fibers 2 are fixed at both ends of the partition 10 . It should be understood that although the figure shows that the basalt fiber 2 is fixed on the partition 10, the basalt fiber 2 can also be arranged in the descending channel 4 in other ways, such as using a support, using a suspension method, etc., and the specific protection scope should be determined by right What is stated in the Requirements shall prevail. But fixing the basalt fiber to the separator has a further advantage, that is, it can improve the convenience of retrofitting the existing wastewater treatment system. By fixing the basalt fiber to the partition, the basalt fiber and the partition can be made into a whole. For the existing wastewater treatment aeration tank, the whole of the basalt fiber and the partition can be inserted into the aeration tank, so that the aeration The air pool is divided into two channels, the side with the water inlet and aeration system is used as the ascending channel, and the side with the basalt fiber and the water outlet is used as the descending channel, which can easily transform the existing wastewater treatment system. As the structure of the basalt fiber bundles, as mentioned above, the fiber bundles can be suspended vertically, or the fiber bundles can be arranged around the fixed core material, and can be arranged separately in the descending channel or fixed on the partition. In addition, when the structure of the basalt fiber bundle itself is arranged in a fiber bundle environment-friendly fixed core material, as shown in Figure 1, it can be in the form of a fiber bundle spirally surrounding the fixed core material, or as shown in Figure 2, there are multiple The fiber bundle rings are arranged in a staggered way around the central fixed core material. This complex arrangement of fiber bundles further increases the anoxic environment inside the fiber bundles, providing a better growth environment for the growth of denitrifying bacteria.

The bottom end of the partition 10 as mentioned above is connected, and the upper end is used as an overflow port. The basalt fiber is completely immersed in the waste water. The aeration system 5 is arranged at the bottom of the reaction tank. The aeration system adopts an aeration disc or an aeration stone. The flow continuously enters the reactor from the water inlet 6, and is mixed in the aeration zone 3 for nitrification reaction. Part of the waste water descends through the overflow port and the packing area along the channel 4. A large number of microorganisms in the waste water are easy to adhere to and grow on the basalt fiber, especially A large number of nitrifying bacteria and denitrifying bacteria are enriched, and the descending wastewater reaches the bottom of the device, is aerated and mixed, then flows upward through the ascending channel, overflows through the baffle, part of the water is discharged, and part of it enters the descending channel, thus performing high-speed circulation treatment. During the operation of the process, the pH value in the treatment system is regularly detected, and the pH value in the reactor is adjusted to 6-9 through the alkali replenishment liquid port 7. If it is necessary to add an organic carbon source, the organic carbon source can be added to the filling area through the carbon replenishment source port 8. The treated waste water is discharged through outlet 9. Since the effluent is mixed with mud and water, a sedimentation tank needs to be connected outside the reactor for sludge return and discharge.

As shown in FIG. 3 , in the present invention, nitrification and denitrification are carried out simultaneously due to the difference in the concentration of dissolved oxygen in contact between the sludge surface and the interior. As the aerobic nitrification reaction in the outer layer of the sludge proceeds, the nitrifying bacteria convert the ammonia nitrogen in the wastewater into nitrate nitrogen or nitrite nitrogen. At the same time, the denitrification reaction inside the sludge will consume nitrate nitrogen or nitrite nitrogen in time to promote the nitrification reaction. The two work together to achieve efficient removal of total nitrogen. As mentioned above, combined with the arrangement structure of the fiber bundles and the control of the aeration rate, the good formation of the internal anoxic environment and the external oxygen-enriched environment of the overall structure of the fiber bundles is further realized, which is the nitrification reaction on the sludge surface and the internal reaction. The nitrification reaction provides a good microbial growth environment and reaction environment, and realizes the simultaneous progress of nitrification and denitrification reactions.

The present invention will be further described below in conjunction with the embodiments, and these embodiments and drawings are for illustrative purposes only, and are not intended to limit the scope of application of the present invention.

Example

Example 1

The wastewater discharged from a fermentation pharmaceutical company in Henan was used for denitrification treatment. The quality of the influent water is shown in Table 2. All indicators are far from meeting the discharge standards for water pollutants in the fermentation pharmaceutical industry—GB219032008 (water pollution by existing enterprises emission concentration limits). The specific experimental conditions are shown in Table 3. After running for 2 months, the effluent of the sedimentation tank was taken for testing, and the average value was taken.

Table 2 Influent wastewater quality

Table 3 Experimental conditions

Experimental conditions Wastewater treatment capacity (L/d) Reaction tank volume (L) Suspended activated sludge MLSS concentration (mg/L) precise data twenty four 10 3200

Specific steps are as follows:

Taking the wastewater discharged from a fermentation pharmaceutical company in Henan as the object, the method of the present invention was used for experimental verification. The test device is shown in Figure 1.

First, the activated sludge is added to the device of the present invention, and the waste water to be treated is added to the device through the water inlet, and the overall sludge concentration is controlled to be 3500-4000 mg/L. Continuous water intake is adopted, and the water intake flow rate is controlled to be about 1L/h. During the operation, the pH value of the treatment system is detected and adjusted to a fluctuation range of 7.5-8.0, and the dissolved oxygen value in the aeration area of the reactor is controlled to be 3.0-4.0 mg/L by adjusting the aeration flow rate. The organic carbon source is ethanol, and the carbon-to-nitrogen ratio is 5:1, which is added according to the consumption rate. The treated wastewater is discharged into the sedimentation tank from the water outlet, and the sedimentation tank is regularly discharged with mud.

The system has been in operation for 2 months, and the COD of the effluent from the sedimentation tank is about 110mg/L, the content of ammonia nitrogen is 10.8mg/L, and the content of total nitrogen is about 25.9mg/L, which is far lower than the discharge standard of water pollutants in the fermentation pharmaceutical industry, and the removal rate is average. It is more than 95%.

The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings and specific examples, but the present invention is not limited to the above embodiments, and within the scope of knowledge of those of ordinary skill in the art, it can also be implemented without departing from the spirit of the present invention. Various changes are made.

Claims (10)

1. A waste water synchronous nitrification and denitrification denitrification device, comprising a bioreactor, is characterized in that a partition is set in the reaction tank space in the bioreactor, the top of the partition is used as an overflow port, and the bottom of the partition is connected, The reaction tank space on both sides of the partition forms an ascending channel and a descending channel respectively, thereby forming a circulation channel in the bioreactor, wherein an aeration system is set at the bottom of the ascending channel, and the wastewater inlet is set at the bottom of the ascending channel, and the incoming wastewater is aerated The gas is mixed with the water from the descending channel to carry out efficient nitrification reaction. Part of the wastewater in the ascending channel descends along the descending channel through the overflow port, and part of it flows out through the water outlet set at the top of the descending channel of the reaction pool; basalt fiber is set in the descending channel Filler, the filler is completely submerged in the wastewater. The basalt fiber filler is composed of fiber bundles. The fiber bundles are composed of basalt fiber monofilaments with a certain diameter. And denitrifying bacteria can be enriched on the basalt fiber, the wastewater in the descending channel reaches the bottom of the reaction tank, and the bottom of the partition is fully mixed with the influent at the bottom of the ascending channel to perform high-speed circulation treatment. 2. The waste water synchronous nitrification and denitrification denitrification device according to claim 1, characterized in that the basalt fiber filler is formed by hanging fiber bundles vertically, or by arranging fiber bundles around a fixed core material. 3. The waste water synchronous nitrification and denitrification denitrification device according to claim 1, characterized in that, the basalt fiber filler is fixed on the side of the descending channel on the separator. 4. The wastewater synchronous nitrification and denitrification denitrification device according to claim 1, characterized in that the diameter of the basalt fiber filler monofilament is 10-20 μm. 5. A waste water synchronous nitrification denitrification denitrification method, it is characterized in that, described method comprises that waste water is transported in the reaction tank of bioreactor, wherein the space of described reaction tank is provided with clapboard, and the top of clapboard serves as overflow The orifice is connected to the bottom of the partition, and the reaction tank space on both sides of the partition forms an ascending channel and a descending channel, thereby forming a circulation channel in the bioreactor; an aeration system is installed at the bottom of the ascending channel, and the waste water inlet is set at the rising channel. At the bottom of the channel, the wastewater entering through the water inlet is fully mixed with the water coming from the descending channel through aeration to carry out efficient nitrification reaction. The outlet of the reaction tank is set at the top of the descending channel, and the wastewater in the ascending channel passes through the overflow part along the descending channel. Descending, part of it flows out through the water outlet set on the top of the descending channel of the reaction pool; basalt fiber packing is set in the descending channel, and the packing is completely submerged in the waste water. Composed of fiber monofilament, a large number of microorganisms in the wastewater are easy to adhere to the basalt fiber to grow and reproduce, so that the nitrifying bacteria and denitrifying bacteria can be enriched on the basalt fiber, and the falling wastewater passes through the basalt enriched with nitrifying bacteria and denitrifying bacteria Nitrification and denitrification reactions are carried out at the same time; the wastewater reaches the bottom of the reaction tank after synchronous nitrification and denitrification treatment, and fully mixes with the influent at the bottom of the ascending channel to rise, so as to perform high-speed circulation treatment. 6. The wastewater synchronous nitrification and denitrification denitrification method according to claim 5, characterized in that, during the aeration process, the dissolved oxygen concentration in the aeration zone of the reactor is controlled by the aeration system to be 1.0 to 5.0 mg/L . 7. The method for synchronous nitrification and denitrification of wastewater according to claim 5, characterized in that the reaction temperature of the control reactor is 20-35° C., and the pH value is 6-9. 8. The waste water synchronous nitrification and denitrification denitrification method as claimed in claim 5, is characterized in that, the concentration of free sludge in the control reactor is 2.0 ~ 6.0g/L, wherein it is ensured by setting the sludge backflow in the sedimentation tank To stabilize the sludge concentration in the reactor, the sludge reflux ratio is controlled to range from 50% to 100%. 9. The waste water synchronous nitrification denitrification denitrification method as claimed in claim 5, is characterized in that, the waste water to be treated is mainly chlortetracycline waste water, and its ammonia nitrogen concentration is 280～470mg/L, and total nitrogen concentration is 400～650mg/L L, COD concentration is 2000~3000mg/L. 10. The wastewater synchronous nitrification and denitrification denitrification method according to claim 5, characterized in that, the required organic carbon source is supplemented according to the carbon-to-nitrogen mass ratio of 4:1 to 10:1, and the organic carbon source is methanol, ethanol , sodium acetate, glucose, flour, etc.