CN103288211B - Anoxic/aerobic SBR-DEAMOX denitrification process device and method for treating low C/N ratio urban sewage - Google Patents

Abstract

The invention provides a device and method for treating low-C/N (carbon/nitrogen) ratio urban sewage by an anoxic/aerobic SBR-DEAMOX (denitrifying ammonium oxidation) denitrification process. One part of the urban sewage firstly enters an anoxic/aerobic SBR reactor and is subjected to pre-denitrifying and nitrifying reaction; and the produced nitrifying liquid is mixed with the other part of raw sewage, and the mixture enters a partial DEAMOX reactor for denitrification. The method comprises the following steps that: 65-85% of the raw water enters the anoxic/aerobic SBR reactor; the pre-denitrifying process is performed by use of the carbon source in the raw water to reduce the residual NO3<->-N of the system in the previous cycle; the NH4<+>-N is oxidized into NO3<->-N by aeration; the nitrifying liquid and 15-35% of the raw water together enter the DEAMOX reactor; and by taking the NO2<->-N produced by partial denitrifying as an electron acceptor, the NH4<+>-N in the raw water generates N2 through anaerobic ammonium oxidation reaction to realize deep denitrification of low-C/N ratio urban sewage. The technology makes full use of the carbon source in the raw water, does not need an external carbon source, saves energy consumption of aeration, and is an economical and efficient new means for solving the problem in the denitrification of low-C/N ratio urban sewage.

Description

Anoxic/aerobic SBR-DEAMOX denitrification process device and method for treating low C/N ratio urban sewage

technical field

The invention relates to a low-energy-consumption method for treating urban sewage with a low carbon-nitrogen (C/N) ratio, which belongs to the technical field of sewage biological treatment. Specifically, the raw water is divided into two parts, and one part enters an anoxic/aerobic SBR reactor. Make full use of organic matter in raw water through pre-denitrification, followed by aeration for nitrification, nitrification liquid and another part of raw water enter the partial denitrification coupling anaerobic ammonium oxidation (DEAMOX) reactor, and use a small amount of organic matter in raw water to generate through partial denitrification Nitrite nitrogen, and then synchronously with ammonia nitrogen in the raw water, through the anaerobic ammonium oxidation reaction to achieve the removal of water nitrogen in the sewage. The invention fully utilizes the carbon source in the raw water without adding an external carbon source, reduces the oxygen consumption in the aeration process, and reduces the operating cost in the sewage treatment process.

Background technique

In recent years, the phenomenon of eutrophication caused by excessive nitrogen and phosphorus in water bodies has become increasingly serious, and the ecological environment of water areas and human health have been seriously affected. The requirements are more stringent. Biological denitrification technology is currently the most widely used sewage denitrification technology. The principle is to remove nitrogen through the action of nitrifying bacteria and denitrifying bacteria. The key to achieving efficient denitrification is sufficient carbon source. When the influent C/N is relatively low, it is necessary to add an external carbon source to improve the treatment effect, but this not only consumes limited organic resources but also increases the operating cost of the sewage plant.

For urban sewage with low C/N ratio, when the traditional aerobic/anoxic process is used for treatment, the organic matter in the raw water will be consumed in the aeration stage, and the subsequent anoxic denitrification process will lead to incomplete denitrification due to insufficient carbon source , not only wasted the limited carbon source and energy consumption of aeration in raw water, but also the treatment effect was not ideal, and could not meet the strict discharge requirements. The research on denitrification process of urban sewage with low energy consumption and good treatment effect has become an important part of sewage treatment. important work.

The anammox process is a new type of biological denitrification technology. The principle is that under anaerobic conditions, anammox bacteria use NO ₂ ^- -N as the electron acceptor to directly oxidize NH ₄ ⁺ -N to N ₂ . Compared with the traditional process, the anammox process does not require oxygen and organic carbon sources, the output of excess sludge is low, the metabolic activity of anammox bacteria is high, and the process volume conversion rate is high. It is currently recognized as an economical and efficient sewage biological removal process nitrogen pathway. However, the anaerobic ammonium oxidation reaction uses nitrite as the substrate, and usually requires short-cut nitrification as a pretreatment process. The realization of short-cut nitrification is mainly through the limitation of dissolved oxygen, inhibition of free ammonia and high temperature operation, so that the nitrification reaction can only proceed to the step of NO ₂ ^- -N, but it is limited in the practical application of treating low C/N ratio urban sewage, mainly Because the accumulation of nitrite is difficult to maintain stability and the operation of raising the temperature of sewage is more difficult and economically unsuitable.

If a better denitrification effect can be achieved in the case of a relatively low C/N ratio in the treated sewage, and the operating cost of the treatment process can be reduced at the same time, the goal of low energy consumption and high efficiency in urban sewage treatment can be achieved.

Contents of the invention

The purpose of the present invention is to solve the above technical problems, and propose a method for treating low C/N ratio (C/N<4) urban sewage through the anoxic/aerobic SBR-DEAMOX denitrification process, specifically dividing the raw water into Two parts, one part enters the anoxic/aerobic SBR reactor, the carbon source in the raw water is used to remove the remaining NO ₃ ^- -N after the reactor was drained in the previous cycle, and then the NH ₄ ⁺ -N in the raw water is oxidized to NO by aeration ₃ ^- -N, the discharged nitrification liquid and another part of raw water enter the DEAMOX (partial denitrification coupling anaerobic ammonia oxidation) reactor, and use a small amount of carbon source in the raw water to reduce NO ₃ ^- -N in the nitrification liquid to NO ₂ ^- -N, NO ₂ ^- -N and NH ₄ ⁺ -N generate N ₂ through anaerobic ammonium oxidation reaction, so as to achieve the purpose of deep denitrification of urban sewage with low C/N ratio.

The purpose of the present invention is achieved through the following technical solutions:

A device for the anoxic/aerobic SBR-DEAMOX denitrification process is characterized in that it includes a raw water tank 1, an anoxic/aerobic SBR reactor 2, an intermediate water tank 3, and a DEAMOX reactor 4.

Raw water tank 1 is connected with anoxic/aerobic SBR reactor 3 through first peristaltic pump 2.1; The flow meter 2.6 is connected with the aeration head; the left side of the anoxic/aerobic SBR reactor is provided with a residual sludge discharge port 2.8, and the anoxic/aerobic SBR reactor is connected with the intermediate water tank 3; the raw water tank is connected with the second peristaltic pump 3.1 The intermediate water tank is connected; the intermediate water tank is connected with the DEAMOX reactor 4 through the third peristaltic pump 4.1; the DEAMOX reactor is provided with a stirring device 4.2 and a temperature control device 4.3.

The method for treating low C/N ratio urban sewage by anoxic/aerobic SBR-DEAMOX denitrification process is characterized in that it includes the following process:

The DEAMOX reactor is inoculated with anaerobic ammonium oxidation sludge and sludge hydrolysis acidification coupling denitrification sludge at a volume ratio of 2.5 to 3.8:1. After inoculation, the sludge concentration in the DEAMOX reactor is MLSS=1500 to 2500mg/L . Among them, _the sludge hydrolysis acidification coupling denitrification sludge comes from the sludge hydrolysis acidification coupling denitrification reactor that has been ⁱⁿ _operation for more than 6 months ^. The removal rate is 90% to 100%. The sludge has incomplete denitrification characteristics. When the concentration of organic carbon source is low, it can only reduce NO ₃ ^- -N to NO ₂ ^- -N; The mud comes from the anaerobic ammonium oxidation reactor that has been in operation for more than 10 months, and its influent NH ₄ ⁺ -N=20～30mg/L, NO ₂ ^- -N=28～40mg/L, NH ₄ ⁺ -N and NO ₂ ^- -N removal rates were 85% to 94% and 90% to 99%.

65% to 85% of the total sewage treated in each cycle in the raw water tank is pumped into the anoxic/aerobic SBR reactor, and the sludge concentration MLSS is controlled at 1500 to 3000mg/L; the anoxic/aerobic SBR reactor is fed with water Afterwards, anoxic stirring for 1-2 hours; followed by aeration and stirring for 2-4 hours, the dissolved oxygen concentration is controlled at 2.0-4.0 mg/L during the aeration process; after the aeration, the precipitation is 30-60 minutes, and then the nitrifying liquid is discharged to the intermediate water tank. The drainage ratio is 40% to 60%.

15% to 35% of the total amount of sewage treated in each cycle in the raw water tank is pumped into the intermediate water tank and mixed with the nitrifying liquid; the mixed liquid in the intermediate water tank is pumped into the DEAMOX reactor, and after the water intake is completed, it is anoxic and stirred for 2 to 5 hours, and then Precipitate for 30-60 minutes, drain the supernatant, and the drainage ratio is 40%-60%.

Technical principle:

The anoxic/aerobic SBR-DEAMOX denitrification process for treating low C/N ratio urban sewage refers to dividing the total amount of sewage treated in each cycle into two parts. First, 65% to 85% of the sewage enters the anoxic/aerobic SBR reactor. , the remaining NO ₃ ^- -N in the system after the end of the previous cycle uses this part of the organic carbon source in the influent for denitrification, and then through the aerobic stage, the NH ₄ ⁺ -N in the raw water is converted into NO ₃ ^- -N, The discharged nitrification liquid is mixed with another part of the raw water and enters the DEAMOX reactor; the sludge hydrolysis acidification coupling denitrification sludge inoculated in the DEAMOX reactor contains a kind of bacterial flora with incomplete denitrification properties, which has a low concentration of organic matter Under certain conditions, NO ₃ ^- -N can only be reduced to NO ₂ ^- -N; the NO ₂ ^- -N produced by the denitrification process in the DEAMOX reactor is then synchronized with NH ₄ ⁺ -N in the raw water by inoculating the sludge Nitrogen removal is achieved through the action of ammonium oxidizing bacteria.

The anoxic/aerobic SBR-DEAMOX denitrification process involved in the present invention has the following advantages in treating low C/N ratio urban sewage:

1) For the denitrification of urban sewage with low C/N ratio, compared with the traditional nitrification and denitrification process, no additional carbon source is required, and the denitrification process only needs to make full use of the carbon source in the raw water to meet the water discharge requirements;

2) During the treatment process, a part of the organic matter in the sewage is consumed due to pre-denitrification, and the amount of oxygen required in the subsequent aeration process is reduced. In addition, part of the NH ₄ ⁺ -N in the raw water does not need to be oxidized, and is passed through anaerobic ammonium oxidation Reaction and removal, thus saving the required aeration in the entire reaction process, thus greatly reducing the operating costs in the sewage treatment process.

3) The operation of the whole process is simple. It only needs to set the time and influent flow rate of each stage in the reaction process, and there is no need for complicated control process. The effluent TN can meet the discharge standard.

Description of drawings

Figure 1 is a flow chart of anoxic/aerobic SBR-DEAMOX denitrification process for urban sewage with low C/N ratio.

Detailed ways

Below in conjunction with accompanying drawing and specific examples the present invention will be further described:

As shown in Figure 1, the device for anoxic/aerobic SBR-DEAMOX denitrification process includes raw water tank 1, anoxic/aerobic SBR reactor 2, intermediate water tank 3, and DEAMOX reactor 4.

Part of the sewage in the raw water tank 1 is connected to the anoxic/aerobic SBR reactor 2 through the first peristaltic pump 2.1; the reactor is provided with a stirring device 2.2 and a temperature control device 2.3, and the bottom of the reactor is provided with an aeration head 2.4 and an air pump 2.5 is connected to the aeration head through the gas flow meter 2.6; one side of the anoxic/aerobic SBR reactor is provided with a water intake 2.7 and an excess sludge discharge port 2.8, and the anoxic/aerobic SBR reactor is connected to the intermediate water tank 3; the raw water tank The second peristaltic pump 3.1 is connected to the intermediate water tank; the third peristaltic pump 4.1 connects the intermediate water tank to the DEAMOX reactor 4; the DEAMOX reactor is provided with a stirring device 4.2, a temperature control device 4.3 and a water intake 4.4.

Specifically include the following processes:

The DEAMOX reactor is inoculated with anaerobic ammonium oxidation sludge and sludge hydrolysis acidification coupling denitrification sludge at a volume ratio of 3:1. After inoculation, the sludge concentration in the DEAMOX reactor is MLSS=1500-2500mg/L. Among them, _the sludge hydrolysis acidification coupling denitrification sludge comes ^from the sludge hydrolysis acidification coupling denitrification reactor that has been in _operation for more than 6 months ^. The removal rate is 90% to 100%. The sludge has incomplete denitrification characteristics. When the concentration of organic carbon source is low, it can only reduce NO ₃ ^- -N to NO ₂ ^- -N; The mud comes from the anaerobic ammonium oxidation reactor that has been in operation for more than 10 months, and its influent NH ₄ ⁺ -N=20～30mg/L, NO ₂ ^- -N=28～40mg/L, NH ₄ ⁺ -N and NO ₂ ^- -N removal rates were 85% to 94% and 90% to 99%.

^The raw water used _in the experiment is domestic sewage from the Family Hospital of Beijing University of Technology. Between 2.2 and 3.5, it is a typical low C/N ratio urban sewage; the raw water is collected into the raw water tank; the anoxic/aerobic SBR-DEAMOX denitrification process treats a total sewage volume of 7.5L per cycle.

The effective volume of the anoxic/aerobic SBR reactor is 12L, the temperature is controlled at 25-28°C, and the sludge age SRT is controlled at 5 days. Firstly, 80% of the total sewage volume is pumped into the anoxic/aerobic SBR reactor, and the influent volume is 6L; after the influent, anoxic and stirred for 1 hour; then aerated and stirred for 3 hours, the dissolved oxygen concentration in the control system is 2.0-4.0mg/ L; settle for 30 minutes after aeration, then discharge the nitrifying liquid to the intermediate water tank, the drainage ratio is 50%, NH ₄ ⁺ -N=5～10mg/L in the nitrifying liquid, NO ₃ ^- -N=30～40mg/L ;

In the raw water tank, 20% of the total sewage treated in each cycle enters the intermediate water tank through the peristaltic pump. The inflow volume is 2L, and it is mixed with the nitrifying liquid. The mixed liquid COD=60～80mg/L, NH ₄ ⁺ -N=18～26mg/L L, NO ₃ ^- -N=24～32mg/L;

Pump the mixed liquid in the 7.5L intermediate water tank into the DEAMOX reactor, the effective volume of the DEAMOX reactor is 15L, the temperature is controlled at 28-30°C, and the SRT is 30 days. The drainage ratio is 50%, the drainage volume per cycle is 7.5L, the effluent NH ₄ ⁺ -N<2mg/L, TN<5mg/L, and the removal rate of TN reaches 88%-90%.

Continuous test results show that:

Taking actual domestic sewage as influent, the sludge concentration MLSS of the anoxic/aerobic SBR reactor is controlled at 2000-2500mg/L, the SRT is 5 days, the anoxic stirring is 1 hour, the aeration stirring is 3 hours, and the drainage ratio is 50%; at the same time DEAMOX reactor sludge concentration MLSS is controlled at 1500-2500mg/L, SRT is 30 days, drainage ratio is 50%; when the whole system treats sewage 7.5L per cycle, the effluent NH ₄ ⁺ -N<2mg/L, TN<5mg /L, the TN removal rate reaches 91% to 95%, which can realize the deep denitrification of urban sewage.

Claims (2)

1. A device for anoxic/aerobic SBR-DEAMOX denitrification process, characterized in that it includes a raw water tank (1), anoxic/aerobic SBR reactor (2), an intermediate water tank (3), DEAMOX Reactor (4); The raw water tank (1) is connected to the anoxic/aerobic SBR reactor (3) through the first peristaltic pump (2.1); the reactor is equipped with a stirring device (2.2) and a temperature control device (2.3), and a The aeration head (2.4), the air pump (2.5) is connected to the aeration head through the gas flow meter (2.6); the left side of the anoxic/aerobic SBR reactor is provided with an excess sludge discharge port (2.8); the anoxic/aerobic The SBR reactor is connected to the intermediate water tank (3); the raw water tank is connected to the intermediate water tank through the second peristaltic pump (3.1); the intermediate water tank is connected to the DEAMOX reactor (4) through the third peristaltic pump (4.1); the DEAMOX reactor has Stirring device (4.2) and temperature control device (4.3). 2. apply the described device of claim 1 to carry out the method for anoxic/aerobic SBR-DEAMOX denitrification process low C/N ratio urban sewage, it is characterized in that, comprises following process: The DEAMOX reactor is inoculated with anaerobic ammonium oxidation sludge and sludge hydrolysis acidification coupling denitrification sludge at a volume ratio of 2.5 to 3.8:1. After inoculation, the sludge concentration in the DEAMOX reactor is MLSS=1500 to 2500mg/L ; Among them, _the sludge hydrolysis acidification coupling denitrification ^sludge comes from the sludge hydrolysis acidification coupling denitrification reactor that has been in operation for more _than 6 months ^. The N removal rate is 90% to 100%; the anammox sludge comes from the anammox reactor that has been in operation for more than 10 months, and its influent NH ₄ ⁺ -N=20～30mg/L, NO ₂ ^- -N =28～40mg/L, the removal rates of NH ₄ ⁺ -N and NO ₂ ^- -N are 85%～94% and 90%～99% respectively; 65% to 85% of the total amount of sewage treated in the raw water tank per cycle is pumped into the anoxic/aerobic SBR reactor, and the reactor sludge concentration MLSS is controlled to be 1500 to 3000mg/L; the anoxic/aerobic SBR reactor is fed into After watering, anoxic stirring for 1-2 hours; followed by aeration and stirring for 2-4 hours, the dissolved oxygen concentration is controlled at 2.0-4.0 mg/L during the aeration process; after aeration, the precipitation is 30-60 minutes, and then the nitrifying liquid is discharged to the intermediate water tank , the drainage ratio is 40% to 60%; 15% to 35% of the total amount of sewage treated in each cycle in the raw water tank is pumped into the intermediate water tank and mixed with the nitrifying liquid; the mixed liquid in the intermediate water tank is pumped into the DEAMOX reactor; after the DEAMOX reactor enters the water, it is anoxic and stirred for 2 to 5 hours ; Then settle for 30 to 60 minutes, discharge the supernatant, and the drainage ratio is 40% to 60%.