CN112479494A

CN112479494A - Device system for biological denitrification of nitrogen-containing organic wastewater and use method thereof

Info

Publication number: CN112479494A
Application number: CN202011302638.2A
Authority: CN
Inventors: 陈茂霞; 江滔; 常佳丽; 苏泽模; 靳如波
Original assignee: Leshan Normal University
Current assignee: Leshan Normal University
Priority date: 2020-11-19
Filing date: 2020-11-19
Publication date: 2021-03-12

Abstract

The invention relates to a device system for biological denitrification of nitrogen-containing organic wastewater and a use method thereof, wherein the device system comprises an anaerobic tank, an aerobic tank and a sedimentation tank; the anaerobic tank is internally provided with activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria, the top of the other side of the anaerobic tank is provided with a first overflow port, the aerobic tank is internally provided with an aerator, the top of one side of the aerobic tank is provided with a second overflow port, the sedimentation tank is used for carrying out sedimentation separation treatment on sludge and water flowing into the aerobic tank, supernatant at the top of the sedimentation tank is purified water after biological denitrification, and sludge at the bottom of the sedimentation tank flows back into the anaerobic tank. The device has simple system structure and convenient operation. The intracellular carbon source stored in the body by the aerobic denitrifying bacteria in the anaerobic stage can meet the requirement of the aerobic bacteria on a micromolecular carbon source, so that nitrate nitrogen can be smoothly denitrified, and the total nitrogen content in water meets the national discharge standard.

Description

Device system for biological denitrification of nitrogen-containing organic wastewater and use method thereof

Technical Field

The invention relates to the technical field of industrial wastewater treatment, in particular to a device system for biological denitrification of nitrogen-containing organic wastewater and a using method thereof.

Background

When the nitrogen content in the water body is too much, eutrophication is easy to cause, and very serious harm is caused to the ecological environment. The denitrification treatment of water is a necessary process for purifying wastewater. The biological denitrification technology is a common technology in biochemical treatment processes, can effectively remove nitrogen contained in wastewater, and the traditional biological denitrification process usually adopts an autotrophic aerobic nitrification-heterotrophic anoxic denitrification process, but in the traditional denitrification process, the denitrification effect can be inhibited by controlling the activity of nitrate reductase with slightly high dissolved oxygen, so that the development of the biological denitrification process is limited.

Aerobic denitrification refers to a phenomenon that denitrification can occur under aerobic conditions, the reaction is controlled by nitrate reductase which is tolerant to high DO, and in recent years, a mode of realizing biological denitrification by constructing an autotrophic nitrification-aerobic denitrification process is widely applied. However, the heterotrophic-aerobic denitrifying bacteria have strong dependence on micromolecular carbon sources and high C/N of sewage, and the phenomenon of insufficient carbon source supply often occurs, so that nitrate nitrogen cannot be smoothly denitrified, and the total nitrogen of effluent exceeds the standard, thereby limiting the practical application of engineering. Sewage plants often guarantee the denitrification effect of the system by adding an external carbon source, but the cost of water treatment is greatly increased.

Disclosure of Invention

The invention aims to: aiming at the technical problems that the requirement of heterotrophic-aerobic denitrifying bacteria on a carbon source cannot be met in the prior art, so that the total nitrogen of effluent exceeds the standard, or the water treatment cost is increased due to an additional carbon source, the device system for biologically denitrifying the nitrogen-containing organic wastewater and the use method thereof are provided.

In order to achieve the purpose, the invention adopts the technical scheme that:

a device system for biological denitrification of nitrogen-containing organic wastewater comprises an anaerobic tank, an aerobic tank and a sedimentation tank;

the anaerobic tank is internally provided with activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria, one side of the anaerobic tank is provided with a first water inlet, the first water inlet is used for receiving nitrogenous organic wastewater to be treated and introducing the wastewater into the anaerobic tank to be mixed with the activated sludge; a first overflow port is formed in the top of the other side of the anaerobic tank and used for discharging the sludge and the sewage mixed in the anaerobic tank into the aerobic tank;

the aerobic tank is internally provided with an aerator, the top of one side of the aerobic tank, which is far away from the first overflow port, is provided with a second overflow port, and the second overflow port is used for overflowing the aerated muddy water in the aerobic tank into the sedimentation tank;

the sedimentation tank is used for carrying out sedimentation separation treatment on mud and water flowing into the aerobic tank, a third overflow port is arranged at the top of one side of the sedimentation tank, and the third overflow port is used for discharging supernatant liquor at the top of the sedimentation tank; a sludge return pipe is arranged at the bottom of the sedimentation tank, one end of the sludge return pipe is communicated with the bottom of the sedimentation tank, and the other end of the sludge return pipe is communicated with the anaerobic tank; the sludge return pipe is used for returning the sludge at the bottom of the sedimentation tank to the anaerobic tank.

The invention provides a biological denitrification device system which mainly comprises an anaerobic tank, an aerobic tank and a sedimentation tank, wherein the anaerobic tank is internally provided with active sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria, the active sludge is mixed with sewage after the sewage to be treated is introduced, the heterotrophic-aerobic denitrifying bacteria absorb organic matters in the sewage and convert the organic matters into intracellular carbon sources in the mixing process, then sludge water enters the aerobic tank and autotrophic nitrifying bacteria convert ammonia nitrogen in the sewage into nitrate nitrogen under the aeration condition, the aerobic denitrifying bacteria convert the nitrate nitrogen into nitrogen under the denitrification action, biological denitrification is completed, and then the active sludge after sludge-water separation can be recycled. The device has simple system structure and convenient operation. The intracellular carbon source stored in the body by the aerobic denitrifying bacteria in the anaerobic stage can meet the requirement of the aerobic bacteria on a micromolecular carbon source, so that nitrate nitrogen can be smoothly denitrified, and the total nitrogen content in water meets the national discharge standard.

Furthermore, a baffle device is arranged in the anaerobic tank. In the anaerobism pond, during sewage and mud mix the back from overflowing to good oxygen pond from the anaerobism pond, set up baffle device, can guarantee certain velocity of flow and turbulence, make mud and water intensive mixing, avoid intaking can flow to good oxygen pond very fast and cause the bottom in anaerobism pond to become the dead angle, muddy water can become the stagnant water inside.

Furthermore, a pump is arranged on the sludge return pipe.

Furthermore, a flowmeter and a valve are arranged on the first water inlet and the sludge return pipe. The flow meter and the valve are arranged to control the mixing of the activated sludge and the sewage in the anaerobic tank.

Furthermore, the device system for the biological denitrification of the nitrogen-containing organic wastewater is of an integrally formed structure.

Furthermore, the bottom of the sedimentation tank is provided with an inclined plate device which is used for receiving the precipitated sludge and gathering the sludge at the bottom of the sedimentation tank. The inclined plate device is more beneficial to the deposition of sludge at the bottom of the sedimentation tank, so that the supernatant at the top of the sedimentation tank is clearer.

The invention also aims to provide the biological denitrification device system and the use method thereof.

A use method of a device system for biological denitrification of nitrogen-containing organic wastewater comprises the following steps:

step 1, introducing nitrogen-containing organic wastewater to be treated into activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria in an anaerobic tank, mixing the activated sludge with sewage for 30-60 min to obtain a first sludge-water mixture, and overflowing the first sludge-water mixture into the aerobic tank;

step 2, carrying out aeration treatment on the first sludge-water mixture in the aerobic tank to obtain a second sludge-water mixture, and overflowing the second sludge-water mixture into the sedimentation tank;

and 3, carrying out precipitation separation treatment on the second sludge-water mixture overflowing to the sedimentation tank, refluxing the sludge obtained by separation to the anaerobic tank in the step 1, and separating to obtain water, namely the purified water after biological denitrification.

The biological denitrification method provided by the invention mainly comprises three steps, namely storing the carbon source by using heterotrophic bacteria in the activated sludge under the anaerobic condition, the principle of storing organic matters in sewage as an intracellular carbon source is that firstly, the activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria is domesticated, then the activated sludge is introduced into an anaerobic tank, after the nitrogenous organic wastewater to be treated is introduced into the anaerobic tank, heterotrophic-aerobic denitrifying bacteria absorb organic matters in the wastewater and convert the organic matters into intracellular carbon sources under anaerobic conditions, then the sludge water in the anaerobic tank is introduced into an aerobic tank, under the aeration condition, the autotrophic nitrifying bacteria convert ammonia nitrogen in the wastewater into nitrate nitrogen, the aerobic denitrifying bacteria convert the nitrate nitrogen into nitrogen under the denitrification action, biological denitrification is completed, and the bacteria in the sludge obtained by separation in the sedimentation tank can be recycled. The intracellular carbon source stored in the aerobic denitrifying bacteria can meet the requirement of the aerobic denitrifying bacteria on a small molecular carbon source, so that nitrate nitrogen can be smoothly denitrified, and the total nitrogen content in water meets the national discharge standard. Compared with the traditional biological denitrification process, the biological denitrification method provided by the invention can realize synchronous nitrification and denitrification, thereby reducing the time and space cost of sewage treatment; the biological denitrification process has low cost, does not need additional carbon sources, and can meet the requirement of heterotrophic-aerobic denitrifying bacteria on the carbon sources, so that the total nitrogen in the purified water reaches the national emission standard.

Further, in the step 1, the nitrogen-containing organic wastewater to be treated is sewage containing organic matters, ammonia nitrogen, nitrite nitrogen and nitrate nitrogen.

Further, in the step 1, the COD concentration in the nitrogen-containing organic wastewater to be treated is 200 mg/L-1000 mg/L, and the total nitrogen (the sum of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen) concentration is 20 mg/L-150 mg/L.

Further, the carbon source includes an organic substance.

Further, the temperature of the nitrogen-containing organic wastewater to be treated is 16-28 ℃. The active sludge has over low nitrification and denitrification efficiency below 16 ℃, which causes the obvious reduction of biological denitrification efficiency. The temperature is too high, which can damage the thalli and further influence the biological denitrification effect. Preferably, the temperature of the nitrogen-containing organic wastewater to be treated is 20-28 ℃, and more preferably, the temperature of the nitrogen-containing organic wastewater to be treated is 25-28 ℃.

Further, in the step 1, MLSS in the anaerobic pool is greater than or equal to 2500 mg/L. In the above description, MLSS is a short term for mixed liquid suspended solids concentration (mixed liquid suspended solids), and is also called mixed liquid sludge concentration. It represents the total weight (mg/L) of activated sludge solids contained in the mixed liquid per unit volume of the aeration tank.

Further, in the step 1, the mixing time is 30min to 40 min. The step 1 mainly has the effects that heterotrophic aerobic denitrifying bacteria absorb organic matters in sewage and convert the organic matters into intracellular carbon sources under anaerobic conditions, too short mixing residence time is not beneficial to the sufficient implementation of the carbon source storage effect of the heterotrophic bacteria, or the denitrification effect is poor, but too long mixing time leads the organic matters to be utilized by the anaerobic heterotrophic bacteria in the activated sludge, and the waste of the organic matters is caused.

Further, in the step 2, the aeration rate is 8L/min to 10L/min.

Further, in the step 2, the aeration time is 2-4 h.

Further, in the step 2, the pH value of the first muddy water mixture is 6-8.

Further, in the step 2, the dissolved oxygen in the aerobic tank is 3 mg/L-6 mg/L. Preferably, in the step 2, the dissolved oxygen in the aerobic tank is 5 mg/L-6 mg/L. The dissolved oxygen is higher, the exogenous toxicity is lower, can provide good nutrient condition for autotrophic nitrifying bacteria and aerobic denitrifying bacteria at the same time, and in addition, the organic matter in the pool is fully removed under the aerobic condition.

Further, in the step 1, the activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria is domesticated by the following method, and the method comprises the following steps:

step S1, taking activated sludge with stable denitrification effect, adjusting MLSS to 3000-5000 mg/L, taking an aerobic denitrification culture medium with C/N of 18-22 and nitrate as a nitrogen source as inflow water, and carrying out batch operation according to a sequence of 'water inflow-anaerobic process-aerobic process-standing-water outflow' as a first period, wherein 8-12 first periods are operated in total; obtaining first activated sludge;

wherein in the anaerobic process, the stirring residence time is 20-40 min, and the stirring speed is 50-80 r/min; in the aerobic process, the aeration amount is 8-10L/min, and the aeration time is 2-3 h;

s2, taking the first activated sludge obtained in the step S1, adjusting MLSS to 3000-5000 mg/L, taking an aerobic denitrification culture medium with 2-5C/N and nitrate as a nitrogen source as inflow water, and carrying out sequencing batch operation for 3-4 second periods in a second period of 'water inflow-anaerobic process-aerobic process-standing-water outflow'; adjusting the C/N of the inlet water to be 18-22, performing sequencing batch operation in a third period according to the sequence of water inlet-anaerobic process-aerobic process-standing-water outlet, and performing 1 third period; then repeating the operation of 3-4 second periods and 1 third period for 6-9 times to obtain activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria;

wherein in the anaerobic process, the stirring residence time is 20-40 min, and the stirring speed is 50-80 r/min; in the aerobic process, the aeration amount is 8-10L/min, and the aeration time is 2-3 h.

The domestication method mainly comprises two steps, wherein in the first step, the activated sludge with stable denitrification effect is domesticated into the activated sludge enriched with aerobic nitrifying bacteria, the aerobic nitrifying bacteria in the activated sludge obtained in the first step are adapted to the environment with the C/N of 18-22, and then in the second step, the condition that the C/N in a culture medium is limited to 2-5 is adopted, and the aerobic nitrifying bacteria in the finally domesticated activated sludge are more adapted to the living environment with low C/N through circulating enrichment, so that the storage and conversion efficiency of the aerobic denitrifying bacteria to organic matters under the anaerobic condition can be effectively improved.

Further, MLSS is a shorthand for mixed liquor suspended solids concentration (mixed liquid suspended solids), which is also known as mixed liquor sludge concentration. It represents the total weight (mg/L) of activated sludge solids contained in the mixed liquid per unit volume of the aeration tank.

Further, in step S1, the aerobic denitrification medium mainly contains the following raw materials: 2.5-4 g/L of sodium acetate, 0.35-0.6 g/L of potassium nitrate, 0.1-0.2 g/L of composite potassium salt, 0.1g/L of magnesium sulfate heptahydrate, 1-5 ml/L of trace element solution and 1-2 ml/L of ammonium ferrous sulfate solution;

the compound potassium salt is potassium dihydrogen phosphate: dipotassium hydrogen phosphate 1: 1.

Further, in the step S2, in the second period, an aerobic denitrification medium with a C/N ratio of 2 to 3 and nitrate as a nitrogen source is used as the feed water. In the domestication process, the aerobic denitrifying bacteria are given a low C/N environment, so that the activated sludge of the aerobic denitrifying bacteria with low C/N tolerance can be enriched, the survival capability of the bacteria in the activated sludge can be effectively improved, and the capability of converting an intracellular carbon source can be effectively improved.

Further, the activated sludge with stable denitrification effect refers to activated sludge with ammonia nitrogen removal rate not lower than 8 mg/L.h. Preferably, the ammonia nitrogen removal rate is 8 mg/L.h-12 mg/L.h.

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:

1. the biological denitrification device system mainly comprises an anaerobic tank, an aerobic tank and a sedimentation tank, wherein the anaerobic tank is internally provided with activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria, and through the synergistic effect of the three purification tanks, intracellular carbon sources stored in the body by the aerobic denitrifying bacteria in the anaerobic stage can meet the requirement of the aerobic stage on small molecular carbon sources, so that nitrate nitrogen can be smoothly denitrified, and further the total nitrogen content in water meets the national discharge standard.

2. The biological denitrification method provided by the invention mainly comprises three steps, by utilizing the principle that heterotrophic bacteria in the activated sludge have the function of storing a carbon source under anaerobic conditions and can store organic matters in sewage as an intracellular carbon source, firstly acclimating the activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria, then introducing the activated sludge into an anaerobic tank, introducing the nitrogen-containing organic wastewater to be treated into the anaerobic tank, absorbing the organic matters in the wastewater by the heterotrophic-aerobic denitrifying bacteria and converting the organic matters into the intracellular carbon source under the anaerobic conditions, then introducing muddy water in the anaerobic tank into an aerobic tank, converting ammonia nitrogen in the wastewater into nitrate nitrogen by the autotrophic nitrifying bacteria under aeration conditions, converting the nitrate nitrogen into nitrogen by the aerobic denitrifying bacteria under the denitrifying action to complete biological denitrification, wherein the intracellular carbon source stored in the anaerobic tank can meet the requirement of the aerobic denitrifying bacteria on a small-molecule carbon source, so that the nitrate nitrogen can be smoothly denitrified, and the total nitrogen content in the water can meet the national discharge standard. Compared with the traditional biological denitrification process, the biological denitrification method provided by the invention can realize synchronous nitrification and denitrification, thereby reducing the time and space cost of sewage treatment; the biological denitrification process has low cost, does not need additional carbon sources, and can meet the requirement of heterotrophic-aerobic denitrifying bacteria on the carbon sources, so that the total nitrogen in the purified water reaches the national emission standard.

Drawings

FIG. 1 is a schematic view showing the system structure of the apparatus used in the biological denitrification process in example 1.

Icon: 1-an anaerobic tank; 11-a first water inlet; 111-a first flow meter; 112-a first valve; 12-a baffle; 13-a first overflow; 2-an aerobic tank; 21-a second overflow; 22-an aerator; 3-a sedimentation tank; 31-a third overflow; 32-a sludge return pipe; 321-a pump; 322-a second flow meter; 323-a second valve; 33-sloping plate device.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

MLSS is a shorthand for mixed liquor suspended solids concentration (mixed liquid suspended solids), which is also known as mixed liquor sludge concentration. It represents the total weight (mg/L) of activated sludge solids contained in the mixed liquid per unit volume of the aeration tank.

DO refers to dissolved oxygen.

COD refers to the chemical oxygen demand, here indicative of the amount of carbon source.

Example 1

As shown in fig. 1, the device system for the biological nitrogen removal of nitrogen-containing organic wastewater is an integrated structure and comprises an anaerobic tank 1, an aerobic tank 2 and a sedimentation tank 3;

the anaerobic tank 1 is internally provided with activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria, one side of the anaerobic tank 1 is provided with a first water inlet 11, and the first water inlet 11 is provided with a first flowmeter 111 and a first valve 112. The top of the other side of the anaerobic tank 1 is provided with a first overflow port 13, and a baffle device 12 is arranged in the anaerobic tank 1. The baffle device 12 is a baffle structure arranged in the middle of the anaerobic tank 1, and water entering the anaerobic tank 1 firstly flows into one side of the baffle and then flows into the other side of the baffle from the bottom of the baffle to carry out sewage diversion. In anaerobism pond 1, during sewage and mud mixed back from overflowing to good oxygen pond from the anaerobism pond, set up baffle device, can guarantee certain velocity of flow and turbulence, make mud and water intensive mixing, avoid intaking can flow to good oxygen pond very fast and cause the bottom in anaerobism pond to become the dead angle, muddy water can become the stagnant water inside.

The aerobic tank 2 is provided with an aerator 22, the top of one side of the aerobic tank 2 is provided with a second overflow port 21, the top of one side of the sedimentation tank 3 is provided with a third overflow port 31, the bottom of the sedimentation tank 3 is provided with an inclined plate device 33, and the inclined plate device 33 is used for receiving precipitated sludge and gathering the sludge at the bottom of the sedimentation tank 3. The inclined plate device is more beneficial to the deposition of sludge at the bottom of the sedimentation tank, so that the supernatant at the top of the sedimentation tank is clearer. A sludge return pipe 32 is arranged at the bottom of the sedimentation tank 3, one end of the sludge return pipe 32 is communicated with the bottom of the sedimentation tank 3, and the other end of the sludge return pipe 32 is communicated with the anaerobic tank 1; the sludge return pipe 32 is provided with a pump 321. The sludge return pipe 32 is provided with a second flow meter 322 and a second valve 323. The flow meter and the valve are arranged to control the mixing of the activated sludge and the sewage in the anaerobic tank.

The invention provides a biological denitrification device system which mainly comprises an anaerobic tank, an aerobic tank and a sedimentation tank, wherein the anaerobic tank is internally provided with active sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria, the active sludge is mixed with sewage after the sewage to be treated is introduced, the heterotrophic-aerobic denitrifying bacteria absorb organic matters in the sewage and convert the organic matters into intracellular carbon sources in the mixing process, then sludge water enters the aerobic tank and autotrophic nitrifying bacteria convert ammonia nitrogen in the sewage into nitrate nitrogen under the aeration condition, the aerobic denitrifying bacteria convert the nitrate nitrogen into nitrogen under the denitrification action, biological denitrification is completed, and then the active sludge after sludge-water separation can be recycled. The intracellular carbon source stored in the body of the aerobic denitrifying bacteria can meet the requirement of the aerobic denitrifying bacteria on a micromolecular carbon source, so that nitrate nitrogen can be smoothly denitrified, and further the total nitrogen content in water meets the national discharge standard.

Example 2

Activated sludge with good denitrification performance in urban sewage treatment A plant is taken and placed in a reactor provided with an aeration device, and the removal rate of ammonia nitrogen in the activated sludge can reach 10 mg/L.h. Adjusting MLSS to 3500 +/-50 mg/L, and taking an aerobic denitrification culture medium with C/N of 20 and nitrate as a nitrogen source as inlet water. The process is operated in a periodic sequence batch mode according to the sequence of 'water inlet → anaerobic (stirring at 35min, 70 r/min) → aerobic (aeration at 3h, 10L/min) → static (aeration at 1h) → water outlet', and the process is operated for 10 periods in total. During the run, the temperature was controlled at 20. + -. 0.5 ℃.

Aerobic denitrification culture medium: 4g/L of sodium acetate, 0.6g/L of potassium nitrate, 0.2g/L of composite potassium salt (monopotassium phosphate: dipotassium hydrogen phosphate: 1), 0.1g/L of magnesium sulfate heptahydrate, 5ml/L of trace element solution and 2ml/L of ammonium ferrous sulfate solution.

Example 3

The activated sludge enriched in aerobic denitrification flora in example 2 was taken and placed in a reactor equipped with an aeration apparatus, and MLSS was adjusted to 3500. + -. 50 mg/L. The aerobic denitrification culture medium is adopted as inflow water, the ratio of sodium acetate to potassium nitrate in the culture medium is adjusted to realize that the C/N of the inflow water is 4, and the operation is carried out in a sequencing batch mode for 4 periods according to the sequence of 'inflow water → anaerobic (stirring at 35min and 60 r/min) → aerobic (aeration at 2.5h and 10L/min) → static (1h) → outflow water'. Then adjusting the C/N of the inlet water to be 20 +/-0.5, and operating for 1 period according to the same operating parameters. Repeating the above steps for 8 times, and acclimating to obtain activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria.

Example 4

The acclimated activated sludge of example 3 containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria was added to the anaerobic tank 1 using the apparatus system described in example 1. Then introducing the nitrogenous organic wastewater to be treated into the activated sludge in the anaerobic tank 1 from the first water inlet 11, and controlling by a flowmeter and a valve, wherein the MLSS in the anaerobic tank 1 is 3800 mg/L. The COD concentration in the organic wastewater is 420 +/-50 mg/L, the ammonia nitrogen is 120 +/-5 mg/L, and the water temperature is 25 +/-2 ℃; mixing the wastewater and the activated sludge for 40min to obtain a first sludge-water mixture; in the first sludge-water mixture, the heterotrophic-aerobic denitrifying bacteria absorb part of the organic matters in the wastewater and convert the organic matters into intracellular carbon sources.

Then, overflowing the first muddy water mixture from the first overflow port 13 into the aerobic tank 2, aerating, controlling the dissolved oxygen DO to be 5.0mg/L, and aerating for 2.5 hours to obtain second muddy water mixture;

and finally, overflowing the second mixed mud water from the second overflow port 21 into the sedimentation tank 3 for mud-water separation, overflowing the supernatant of the separated sedimentation tank 3 from the third overflow port 31 to obtain purified water after biological denitrification, returning the bottom sludge of the separated sedimentation tank 3 into the anaerobic tank 1 by using a sludge return pipe 32, and reusing the activated sludge in the sludge.

Through detection, the COD in the purified water is 22mg/L, the ammonia nitrogen is 3.1mg/L, and the total nitrogen is 5.9 mg/L.

Example 5

The acclimated activated sludge of example 3 containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria was added to the anaerobic tank 1 using the apparatus system described in example 1. Then the nitrogenous organic wastewater to be treated is introduced into the activated sludge in the anaerobic tank 1 from the first water inlet 11, and the MLSS in the anaerobic tank 1 is 3000mg/L under the control of a flowmeter and a valve. The COD concentration in the organic wastewater is 250 +/-50 mg/L, the ammonia nitrogen is 60 +/-5 mg/L, and the water temperature is 24 +/-0.5 ℃; mixing the wastewater and the activated sludge for 60min to obtain a first sludge-water mixture; in the first sludge-water mixture, the heterotrophic-aerobic denitrifying bacteria absorb part of the organic matters in the wastewater and convert the organic matters into intracellular carbon sources.

Then, overflowing the first muddy water mixture from the first overflow port 13 into the aerobic tank 2, aerating, controlling the dissolved oxygen DO to be 4.0mg/L, and aerating for 4 hours to obtain second muddy water mixture;

finally, the second mixed muddy water overflows from the second overflow port 21 to the sedimentation tank 3 for muddy water separation,

the separated supernatant of the sedimentation tank 3 overflows from the third overflow port 31 to obtain purified water after biological denitrification, the separated sludge at the bottom of the sedimentation tank 3 flows back to the anaerobic tank 1 by using a sludge return pipe 32, and the activated sludge in the sludge is reused.

Through detection, the COD in the purified water is 28mg/L, the ammonia nitrogen is 3.5mg/L, and the total nitrogen is 6.4 mg/L.

Example 6

By using the device system described in example 1, the activated sludge enriched in aerobic denitrification flora in example 2 was taken and placed in a reactor equipped with an aeration device, and MLSS was adjusted to 3500. + -. 50 mg/L. The aerobic denitrification culture medium is adopted as inflow water, the ratio of sodium acetate to potassium nitrate in the culture medium is adjusted to realize that the C/N of the inflow water is 2, and the operation is carried out in a periodic sequence batch mode according to the sequence of 'inflow water → anaerobic (stirring at 35min and 60 r/min) → aerobic (aeration at 2.5h and 10L/min) → standing → outflow water', and the operation lasts for 4 periods in total. Then adjusting the C/N of the inlet water to be 20 +/-0.5, and operating for 1 period according to the same operating parameters. Repeating the above steps for 8 times, and acclimating to obtain activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria.

Treating and purifying the acclimated activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria by adopting the completely same denitrification process of the embodiment 4, wherein the process parameters and the nitrogen-containing organic wastewater to be treated in the purification process are the same as those in the embodiment 4, introducing the first mixed sludge water into the aerobic tank 2, aerating, controlling the dissolved oxygen DO to be 5.0mg/L, and stopping aeration after the aeration time is 2 hours, wherein the ammonia nitrogen content in the aerobic tank 2 does not change within half an hour, so as to obtain second mixed sludge water; through detection, the COD in the purified water is 20mg/L, the ammonia nitrogen is 2.8mg/L, and the total nitrogen is 5.5 mg/L.

Researches show that the aerobic denitrifying bacteria cultured under the condition that C/N is 2 have better effect of storing carbon sources and improve the denitrification speed and effect.

Example 7

Activated sludge with good denitrification performance in town sewage treatment B plants is taken and placed in a reactor provided with an aeration device, and the removal rate of ammonia nitrogen in the activated sludge can reach 12 mg/L.h. MLSS is adjusted to be 4200 +/-50 mg/L, and aerobic denitrification culture medium with C/N of 22 and nitrate as nitrogen source is adopted as inflow water. The process is carried out by taking 'water inlet → anaerobic (40min, 80r/min stirring) → aerobic (3h, 9L/min aeration) → static (1h) → water outlet' as a period and sequencing batch operation, and the total period is 12. During the run, the temperature was controlled at 20. + -. 0.5 ℃.

Aerobic denitrification culture medium: 3.5g/L of sodium acetate, 0.5g/L of potassium nitrate, 0.15g/L of composite potassium salt (monopotassium phosphate: dipotassium hydrogen phosphate: 1), 0.1g/L of magnesium sulfate heptahydrate, 3ml/L of trace element solution and 1.5ml/L of ammonium ferrous sulfate solution.

By using the system of example 1, the activated sludge enriched by aerobic denitrification flora was taken and placed in a reactor equipped with an aeration apparatus, and MLSS was adjusted to 3500. + -. 50 mg/L. The aerobic denitrification culture medium is adopted as inflow water, the ratio of sodium acetate to potassium nitrate in the culture medium is adjusted to realize that the C/N of the inflow water is 10, and the operation is carried out in a periodic sequence batch mode according to the sequence of 'inflow water → anaerobic (stirring at 35min and 60 r/min) → aerobic (aeration at 2.5h and 10L/min) → standing → outflow water', and the operation lasts for 4 periods in total. Then adjusting the C/N of the inlet water to be 20 +/-0.5, and operating for 1 period according to the same operating parameters. Repeating the above steps for 8 times, and acclimating to obtain activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria.

Treating and purifying the acclimated activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria by adopting the completely same denitrification process of the embodiment 4, wherein the process parameters and the nitrogen-containing organic wastewater to be treated in the purification process are the same as those in the embodiment 4, introducing the first mixed sludge water into the aerobic tank 2, aerating, controlling the dissolved oxygen DO to be 5.0mg/L, and stopping aeration after the aeration time is 3.5 hours, wherein the ammonia nitrogen content in the aerobic tank 2 does not change within half an hour, so as to obtain second mixed sludge water; through detection, the COD in the purified water is 25mg/L, the ammonia nitrogen is 4.2mg/L, and the total nitrogen is 6.7 mg/L.

Comparative example 1

By using the device system described in example 1, the acclimatized activated sludge of example 3 containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria was added to the aerobic tank 2, and the MLSS in the aerobic tank 2 was 3800 mg/L. Then introducing the nitrogenous organic wastewater to be treated into activated sludge in an aerobic tank 2, wherein the COD concentration in the organic wastewater is 420 +/-50 mg/L, the ammonia nitrogen is 120 +/-5 mg/L, and the water temperature is 25 +/-2 ℃; then, aerating, controlling the dissolved oxygen DO to be 5.0mg/L, and stopping aeration after the aeration time is 3.5 hours and the ammonia nitrogen content in the aerobic tank 2 does not change within half an hour to obtain second mixed muddy water;

and finally, introducing the second mixed muddy water into the sedimentation tank 3 for muddy water separation to obtain the purified water subjected to biological denitrification.

Through detection, the purified water has 75mg/L of COD, 41.5mg/L of ammonia nitrogen and 18.2mg/L of total nitrogen.

Comparative example 1 the biological denitrification process provided by the invention is not adopted, the operation of adsorbing and storing intracellular carbon sources in the anaerobic tank 1 is not carried out on the activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria, but the activated sludge and the organic wastewater are directly introduced into the aerobic tank 2 for aeration, and researches show that the dependence of the heterotrophic-aerobic denitrifying bacteria on micromolecular carbon sources is strong, the phenomenon of insufficient carbon source supply occurs, and the total nitrogen content of effluent exceeds the standard.

Comparative example 2

Comparative example 1 is the same as the denitrification process of example 4, except that the mixing retention time in the anaerobic tank 1 is 20min, and the detection shows that the COD in the purified water is 30mg/L, the ammonia nitrogen is 5.4mg/L, and the total nitrogen is 25.6 mg/L.

The biological denitrification method provided by the invention mainly comprises three steps, by utilizing the principle that heterotrophic bacteria in the activated sludge have the function of storing a carbon source under anaerobic conditions and can store organic matters in sewage as an intracellular carbon source, firstly acclimating the activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria, then introducing the activated sludge into an anaerobic tank, introducing the nitrogenous organic wastewater to be treated into the anaerobic tank, absorbing the organic matters in the wastewater by the heterotrophic-aerobic denitrifying bacteria and converting the organic matters into the intracellular carbon source under the anaerobic conditions, then introducing muddy water in the anaerobic tank into an aerobic tank, converting ammonia nitrogen in the wastewater into nitrate nitrogen by the autotrophic nitrifying bacteria under aeration conditions, converting the nitrate nitrogen into nitrogen by the aerobic denitrifying bacteria under the denitrification to complete biological denitrification, and storing the aerobic denitrifying bacteria in the intracellular carbon source in the anaerobic stage to meet the requirement of the intracellular carbon source in the aerobic stage, so that the nitrate nitrogen can be smoothly denitrified, and the total nitrogen content in the water can meet the national discharge standard. Compared with the traditional biological denitrification process, the biological denitrification method provided by the invention can realize synchronous nitrification and denitrification, thereby reducing the time and space cost of sewage treatment; the biological denitrification process has low cost, does not need additional carbon sources, and can meet the requirement of heterotrophic-aerobic denitrifying bacteria on the carbon sources, so that the total nitrogen in the purified water reaches the national emission standard.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. The device system for biological denitrification of the nitrogen-containing organic wastewater is characterized by comprising an anaerobic tank (1), an aerobic tank (2) and a sedimentation tank (3);

the anaerobic tank (1) is internally provided with activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria, one side of the anaerobic tank (1) is provided with a first water inlet (11), and the first water inlet (11) is used for receiving nitrogenous organic wastewater to be treated and introducing the wastewater into the anaerobic tank (1) to be mixed with the activated sludge; a first overflow port (13) is formed in the top of the other side of the anaerobic tank (1), and the first overflow port (13) is used for discharging the sludge and the sewage mixed in the anaerobic tank (1) into the aerobic tank (2);

an aerator (22) is arranged in the aerobic tank (2), a second overflow port (21) is arranged at the top of one side of the aerobic tank (2) far away from the first overflow port (13), and the second overflow port (21) is used for overflowing aerated muddy water in the aerobic tank (2) into the sedimentation tank (3);

the sedimentation tank (3) is used for carrying out sedimentation separation treatment on mud and water flowing into the aerobic tank (2), a third overflow port (31) is formed in the top of one side of the sedimentation tank (3), and the third overflow port (31) is used for discharging supernatant liquid on the top of the sedimentation tank (3); a sludge return pipe (32) is arranged at the bottom of the sedimentation tank (3), one end of the sludge return pipe (32) is communicated with the bottom of the sedimentation tank (3), and the other end of the sludge return pipe (32) is communicated with the anaerobic tank (1); the sludge return pipe (32) is used for returning the sludge at the bottom of the sedimentation tank (3) to the anaerobic tank (1).

2. The system of claim 1, wherein the system is an integrated structure.

3. The system for the biological nitrogen removal of nitrogen-containing organic wastewater according to claim 1, wherein a flow meter and a valve are provided on each of the first water inlet (11) and the sludge return pipe (32).

4. The apparatus system for the biological nitrogen removal of nitrogen-containing organic wastewater according to claim 1, wherein a pump (321) is provided on the sludge return pipe (32).

5. The system for the biological nitrogen removal of nitrogen-containing organic wastewater according to any one of claims 1 to 4, characterized in that the bottom of the sedimentation tank (3) is provided with an inclined plate device (33), and the inclined plate device (33) is used for receiving and gathering the settled sludge at the bottom of the sedimentation tank (3).

6. Use of the system according to any one of claims 1 to 5, characterized in that it comprises the following steps:

step 1, introducing nitrogen-containing organic wastewater to be treated into activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria in an anaerobic tank (1), mixing the activated sludge with sewage for 30-60 min to obtain a first sludge-water mixture, and overflowing the first sludge-water mixture into an aerobic tank (2);

step 2, carrying out aeration treatment on the first muddy water mixture in the aerobic tank (2) to obtain a second muddy water mixture, and overflowing the second muddy water mixture into the sedimentation tank (3);

and 3, carrying out precipitation separation treatment on the second sludge-water mixture overflowing into the sedimentation tank (3), refluxing the separated sludge into the anaerobic tank (1) in the step 1, and separating to obtain water, namely the purified water after biological denitrification.

7. The use method of the apparatus system for biological nitrogen removal of nitrogen-containing organic wastewater according to claim 6, wherein the mixing retention time in step 1 is 30-40 min.

8. The method for using the apparatus system for biological nitrogen removal of nitrogen-containing organic wastewater according to claim 6, wherein the activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria in the step 1 is acclimatized by the following method, comprising the steps of:

s2, taking the first activated sludge obtained in the step S1, adjusting MLSS to 3000-5000 mg/L, taking an aerobic denitrification culture medium with 2-5C/N and nitrate as a nitrogen source as inflow water, and carrying out sequencing batch operation for 3-4 second periods in a second period of 'water inflow-anaerobic process-aerobic process-standing-water outflow'; adjusting the C/N of the inlet water to be 18-22, performing sequencing batch operation in a third period according to the sequence of water inlet-anaerobic process-aerobic process-standing-water outlet, and performing 1 third period; then repeating the operation of 3-4 second periods and 1 third period for 6-9 times to obtain activated sludge containing heterotrophic-aerobic denitrifying bacteria and autotrophic aerobic nitrifying bacteria; wherein in the anaerobic process, the stirring residence time is 20-40 min, and the stirring speed is 50-80 r/min; in the aerobic process, the aeration amount is 8-10L/min, and the aeration time is 2-3 h.

9. The use method of the apparatus system for biological nitrogen removal of nitrogen-containing organic wastewater according to claim 8,

in the step S1, the aerobic denitrification medium mainly contains the following raw materials: 2.5-4 g/L of sodium acetate, 0.35-0.6 g/L of potassium nitrate, 0.1-0.2 g/L of composite potassium salt, 0.1g/L of magnesium sulfate heptahydrate, 1-5 ml/L of trace element solution and 1-2 ml/L of ammonium ferrous sulfate solution;

10. The use method of the apparatus system for biological nitrogen removal of nitrogen-containing organic wastewater according to claim 8,

in the step S2, in the operation process of the second period, an aerobic denitrification culture medium with 2-3C/N and nitrate as a nitrogen source is used as water inlet.