Method for realizing high-efficiency denitrification of sewage by using urban sewage split-flow carbonization / nitrification treatment combined biological filter

Abstract

The invention relates to a method for realizing high-efficiency denitrification of sewage by using an urban sewage split-flow carbonization / nitration treatment combined biological filter, belonging to the technical field of urban sewage treatment, and the specific scheme is as follows: (1) urban sewage split-flow treatment: carrying out nitration treatment on one part of sewage, and carrying out carbonization treatment on the other part of sewage; (2) carrying out mixed nitrification and carbonization treatment on effluent; and (3) carrying out denitrification treatment on the sewage containing ammonia nitrogen and nitrate nitrogen by using the biological filter. According to the method, sulfur-based autotrophic denitrification and anaerobic ammonia oxidation functional microorganisms are coupled in a single-stage reactor, the reactor operates stably for a long time, autotrophic denitrification provides a nitrite substrate for anaerobic ammonia oxidation, meanwhile, a small amount of nitrate generated by anaerobic ammonia oxidation is reduced and removed, the cooperative relation of the two microorganisms is larger than the competitive relation, and the yield of the microorganisms is increased. And the average removal rate of total nitrogen exceeds 85%. The sewage is subjected to denitrification treatment by the method, and the total nitrogen concentration of the treated effluent reaches the national first-grade A emission standard.

Description

Technical Field

[0001] The invention belongs to the technical field of urban sewage treatment, and in particular relates to a method for realizing efficient denitrification of sewage by using a combined biofilter for urban sewage diversion carbonization / nitrification treatment. Background Art

[0002] Sewage denitrification is a global environmental issue. Traditional sewage treatment processes rely on nitrification and heterotrophic denitrification to remove nitrogen pollutants. This process requires a lot of aeration and often requires the addition of additional organic carbon sources, which not only increases the cost of sewage treatment, but also easily causes secondary pollution of organic matter. It also does not meet the green development goals of "carbon peak and carbon neutrality". Anaerobic ammonia oxidation (Anammox), as a major denitrification pathway, has significant advantages such as low sludge yield, zero oxygen and organic matter consumption, and no greenhouse gas emissions, but the mainstream anaerobic ammonia oxidation process faces great challenges in practical applications. First, the carbon-nitrogen ratio (C / N) of the mainstream process influent is high. A high carbon-nitrogen ratio will promote the proliferation of heterotrophic bacteria, intensify the competition between heterotrophic bacteria and anaerobic ammonia-oxidizing bacteria (AnAOB) for nitrite, and reduce the total nitrogen removal efficiency. Secondly, the ammonia nitrogen concentration in urban sewage is only 20-60 mgN / L. Lack of substrate will inhibit the activity of ammonia oxidizing bacteria (AOB) and anaerobic ammonium oxidizing bacteria, while lower concentrations of free ammonia (FA) and free nitrite (FNA) are difficult to inhibit the activity of nitrite oxidizing bacteria (NOB), resulting in nitrite being oxidized to nitrate, which hinders the occurrence of anaerobic ammonium oxidation. If the existing anaerobic ammonium oxidation process can be modified and improved to protect it from the influence of organic matter in the influent and at the same time have a stable supply of nitrite, it will not only achieve efficient removal of nitrogen in sewage, but also reduce costs. Summary of the invention

[0003] The sewage treatment technology described in the present invention takes urban sewage as the object. In view of the problem that the mainstream anaerobic ammonia oxidation process is inhibited by influent organic matter and the nitrite process is unstable, the present invention provides a method for achieving efficient denitrification of sewage by using a combined biofilter for diversion carbonization / nitrification treatment of urban sewage, which is a new method for removing nitrogen pollutants in sewage.

[0004] The specific plan is as follows:

[0005] A method for realizing efficient denitrification of sewage by using a combined biofilter for carbonization / nitrification treatment of urban sewage diversion, comprising the following steps:

[0006] Step 1: Divide the urban sewage, one part of the sewage is nitrified by long-term aeration and long sludge age, and the other part is carbonized by short-term aeration and short sludge age. The volume ratio of nitrification and carbonization sewage is 1:1-1.2:1; the sludge concentration of the nitrification unit is 3000-5000 mg / L, and the dissolved oxygen concentration is controlled by aeration.

[0007] 1.0-3.0mg / L, aeration time 4-8h, daily sludge discharge makes the sludge age 10-15 days; sludge concentration in carbonization unit is 2000-3500mg / L, dissolved oxygen concentration is controlled at 0.5-1.0mg / L through aeration, aeration time 0.5-2h, daily sludge discharge makes the sludge age within 5 days; the dissolved oxygen concentration in nitrification unit and carbonization unit is monitored by DO online meter, and aeration is controlled by aeration pump.

[0008] Step 2: Mix the effluents from the carbonization treatment and the nitrification treatment; remove the dissolved oxygen in the mixed effluent by nitrogen aeration to make the DO less than 0.2 mg / L;

[0009] Step 3: The mixed effluent enters the upflow anaerobic biofilter reactor from the bottom to achieve simultaneous removal of ammonia nitrogen and nitrate nitrogen; the upflow anaerobic biofilter reactor is filled with a mixture of sulfur and carbonate minerals, and inoculated with sulfur-based autotrophic denitrification sludge and anaerobic ammonia oxidation sludge.

[0010] Furthermore, in step three, the sulfur and carbonate minerals are cleaned of impurities on the surface using 1M dilute hydrochloric acid before use, and then rinsed with clean water until neutral, and then placed in a vacuum oven at 30°C for drying.

[0011] Further, in step 3, the sulfur-based autotrophic denitrification sludge and the anaerobic ammonium oxidation sludge are poured into the upflow anaerobic bioreactor, and the sewage containing 30 mg / L ammonia nitrogen and 40 mg / L nitrite nitrogen is prepared, and the new sewage is replaced after circulating in the upflow anaerobic biofilter reactor for 4 days. The whole process is cycled 10 times, and the sulfur-based autotrophic denitrification sludge and the anaerobic ammonium oxidation sludge are considered to be successfully inoculated. The flow rate of the sewage circulating in the upflow anaerobic biofilter reactor is 10 mL / min.

[0012] Furthermore, in step three, the carbonate mineral includes a combination of one or more of limestone, dolomite, siderite and magnesite.

[0013] Furthermore, in step three, the source of the sulfur-based autotrophic denitrification sludge includes one or a mixture of autotrophic sludge, heterotrophic sludge, and anaerobic sludge; the anaerobic ammonium oxidation sludge includes a mixture of one or more of anaerobic ammonium oxidation granular sludge and anaerobic ammonium oxidation flocculent sludge.

[0014] Furthermore, in step three, the particle shape of the sulfur includes one or a combination of spherical, cylindrical, and flaky.

[0015] Furthermore, the upflow anaerobic biofilter reactor is a fixed bed reactor.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention realizes the coupling of sulfur-based autotrophic denitrification and anaerobic ammonium oxidation functional microorganisms in a single-stage reactor, the reactor operates stably for a long time, the autotrophic denitrification provides nitrite substrate for anaerobic ammonium oxidation, and simultaneously reduces and removes a small amount of nitrate generated by anaerobic ammonium oxidation, the cooperative relationship between the two microorganisms is greater than the competitive relationship, and the average total nitrogen removal rate exceeds 85%. The sewage is denitrified by the method, and the total nitrogen concentration of the treated effluent meets the national Class A emission standard. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the urban sewage treatment process in the present invention;

[0019] Figure 2 This is a schematic diagram of the sulfur-based autotrophic denitrification coupled with anaerobic ammonium oxidation denitrification process;

[0020] Figure 3 Combined biofilter denitrification system for urban sewage diversion carbonization / nitrification treatment;

[0021] Figure 4 The nitrogen removal effect diagram of sulfur-based autotrophic denitrification coupled with anaerobic ammonium oxidation biofilter;

[0022] Figure 5 Total nitrogen removal rate diagram of sulfur-based autotrophic denitrification coupled with anaerobic ammonium oxidation biofilter;

[0023] In the figure, 1. urban sewage, 2. air supply device, 3. DO online measuring instrument, 4. aeration device, 5. nitrification reactor, 6. carbonization reactor, 7. sedimentation tank, 8. intermediate water tank, 9. nitrogen cylinder, 10. peristaltic pump, 11. supporting layer, 12. mixed filler layer, 13. heating belt, 14. temperature controller. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] Sulfur-based autotrophic denitrification (SADn) uses elemental sulfur to reduce NO3 - NO2 will accumulate briefly during the process - , can be consumed as a substrate in the anaerobic ammonium oxidation process. Compared with short-range nitrification, it is not inhibited by NOB. NO2 -The generation of anaerobic ammonium oxidation is more stable. The nitrate produced by the anaerobic ammonium oxidation process can be reduced and removed by autotrophic denitrifying bacteria, which can theoretically achieve complete nitrogen removal. In addition, sulfur autotrophic denitrification and anaerobic ammonium oxidation functional microorganisms are both autotrophic, have the same requirements for many environmental factors, have similar ecological niches, and have long proliferation times, and can be coupled in a single system.

[0026] In order to promote the application of this process, it is necessary to reduce the impact of organic matter in urban sewage on the anaerobic ammonium oxidation process, and it is also necessary to provide nitrate nitrogen for the autotrophic denitrification process. The present invention first diverts urban sewage for nitrification and carbonization treatment, and constructs an upflow anaerobic biofilter with sulfur and carbonate minerals as fillers, and couples sulfur-based autotrophic denitrification and anaerobic ammonium oxidation functional microorganisms to treat sewage containing ammonia nitrogen and nitrate nitrogen. Specifically: the urban sewage is diverted for treatment, and a part of the sewage is nitrified through a biochemical unit with long aeration and long sludge age, and the effluent is mainly nitrate nitrogen; the other part of the sewage is carbonized in a biochemical unit with short aeration and short sludge age, and the effluent is mainly ammonia nitrogen; the mixed effluent from nitrification and carbonization treatment contains NH4 + and NO3 - At the same time, by screening and reasonably matching sulfur and carbonate mineral particles, an upflow anaerobic biofilter reactor was constructed to couple sulfur-based autotrophic denitrification and anaerobic ammonia oxidation functional microorganisms. This filter was used to treat mixed sewage after nitrification and carbonization to achieve the simultaneous removal of ammonia nitrogen and nitrate. The urban sewage treatment process is shown in the figure below. Figure 1 As shown. In the filling material of the upflow anaerobic biofilter reactor, sulfur is used as a slow-release electron donor for sulfur-based autotrophic denitrification, and carbonate minerals are used to neutralize the acidity generated by denitrification to maintain a neutral environment in the system. Autotrophic denitrifying bacteria provide nitrite substrates for anaerobic ammonium oxidizing bacteria, while reducing and removing a small amount of nitrate generated during the anaerobic ammonium oxidation process. The two functional microorganisms work together to remove nitrogen-containing pollutants in sewage. Through this technological innovation, the shortcomings of the mainstream anaerobic ammonium oxidation process are made up, and it is expected to achieve low-carbon and high-efficiency removal of nitrogen-containing pollutants in urban sewage.

[0027] The method of the municipal sewage diversion carbonization / nitrification treatment combined biological filter for achieving efficient sewage denitrification of the present invention has the following denitrification principle: Figure 2 As shown in the figure: When sewage containing ammonia nitrogen and nitrate nitrogen enters the upflow anaerobic biofilter, sulfur-based autotrophic denitrifying bacteria use sulfur as an electron donor for denitrification. The denitrification process is shown in formulas (1) and (2). The intermediate product nitrite of autotrophic denitrification is used by anaerobic ammonium oxidizing bacteria and is removed together with ammonia nitrogen as a substrate of the anaerobic ammonium oxidation process, as shown in formula (3). The small amount of nitrate generated by anaerobic ammonium oxidation can be further reduced and removed by autotrophic denitrification (as shown in formulas (1) and (2)). The H generated in the denitrification process +Reaction with the carbonate mineral limestone (as shown in formula (4)) can maintain the neutral environment of the coupling system and ensure the efficient denitrification ability of relevant functional microorganisms.

[0028]

[0029]

[0030] Urban sewage diversion carbonization / nitrification treatment combined biofilter denitrification system Figure 3 As shown, it includes a nitrification unit 5 and a carbonization unit 6, each unit is provided with an aeration device 4 at the bottom, the aeration device 4 is connected to an air supply device 2, and a DO online measuring instrument 3 is used to measure the dissolved oxygen in the nitrification unit 5 and the carbonization unit 6; after the diversion of the urban sewage 1, the nitrification treatment and the carbonization treatment, the effluent is precipitated in a sedimentation tank 7 and then enters an intermediate water tank 8, the bottom of the intermediate water tank 8 is also provided with an aeration device 4, and the aeration device 4 here is connected to a nitrogen cylinder 9 The nitrogen cylinder 9 supplies nitrogen to the mixed water to reduce the dissolved oxygen concentration of the mixed water. The mixed water enters the upflow anaerobic biofilter from the bottom through the peristaltic pump 10. The bottom of the upflow anaerobic biofilter is a supporting layer 11, and the upper part of the supporting layer 11 is a mixed filler layer 12. A heating belt 13 is wrapped around the outer wall of the upflow anaerobic biofilter to maintain the reaction temperature of the filter at 30±1°C. The heating belt 13 is electrically connected to the temperature controller 14.

[0031] Example 1

[0032] A method for realizing efficient denitrification of sewage by using a combined biofilter for carbonization / nitrification treatment of urban sewage diversion, the application process and denitrification effect of which are as follows:

[0033] (1) Inoculate aerobic tank sludge in the nitrification unit and carbonization unit, with sludge concentrations of 4000 mg / L and 3000 mg / L, respectively;

[0034] (2) Wastewater diversion: The wastewater is diverted to the nitrification unit and the carbonization unit at a volume ratio of 1:1;

[0035] (3) The DO concentration of the nitrification unit is controlled at 1.0-3.0 mg / L and aerated for 5 h;

[0036] (4) The DO concentration of the carbonization unit is controlled at 0.5-1.0 mg / L and aerated for 2 h;

[0037] (5) Mixing the effluent from the nitrification treatment and the effluent from the carbonization treatment, and aerating the mixed water with nitrogen having a purity of 99.99% to reduce the oxygen concentration of the solution in the mixed water to less than 0.2 mg / L;

[0038] (6) Prepare fillers: 350 mL of sulfur granules and 350 mL of limestone granules, both passed through a 2-3 mm sieve;

[0039] (7) Prepare hydrochloric acid with a concentration of 1 M to clean the impurities on the surface of the screened sulfur and limestone particles, and then rinse with clean water until the pH is neutral;

[0040] (8) Place the cleaned filler in a vacuum oven and dry at 30°C;

[0041] (9) The above particles were mixed evenly and filled into an upflow bioreactor (inner diameter 60 mm, support layer height 20 mm, filling height 480 mm), and the support layer used glass beads with a diameter of 10 mm;

[0042] (10) pouring the sulfur-based autotrophic denitrification sludge and the anaerobic ammonium oxidation sludge into an upflow anaerobic bioreactor, the reactor influent contains 30 mg / L ammonia nitrogen and 40 mg / L nitrite nitrogen, and the effluent is recycled into the reactor at a circulation flow rate of 10 mL / min. The influent solution is replaced with a new one every 4 days for a total of 10 cycles;

[0043] (11) After successful biofilm inoculation, the mixed effluent after nitrification and carbonization treatment was used as the influent, with an ammonia nitrogen concentration of 30 mg / L, a nitrate nitrogen concentration of 30 mg / L, and a pH of 8.15±0.5. It was pumped from the bottom into the upflow anaerobic bioreactor, and the hydraulic retention time was gradually shortened from 21 hours to 6.5 hours;

[0044] (12) The nitrogen treatment effect and total nitrogen removal rate of the reactor are as follows Figure 4 and Figure 5 When the hydraulic retention time is 21h, the total nitrogen removal rate can eventually reach 100%. When the hydraulic retention time is 14h, 10.5h and 8.4h, the ammonia nitrogen removal rate shows a trend of first decreasing, then increasing and finally maintaining stability. When the hydraulic retention time is further shortened to 6.5h, the average effluent ammonia nitrogen concentration reaches 7.48±1.92mg / L, and the average total nitrogen removal rate is 87.85±2.85%.

[0045] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for achieving efficient denitrification of urban sewage by using a combined biofilter for carbonization / nitrification treatment, characterized in that: The following steps are involved: Step 1: Divide the urban sewage into two streams. One part of the sewage is treated with nitrification by long-term aeration and long sludge age, and the other part is treated with carbonization by short-term aeration and short sludge age. Step 2: Mix the effluents from the carbonization treatment and the nitrification treatment; Step 3: The mixed effluent enters the upflow anaerobic biofilter reactor from the bottom to achieve simultaneous removal of ammonia nitrogen and nitrate nitrogen; the upflow anaerobic biofilter reactor is filled with a mixture of sulfur and carbonate minerals, and inoculated with sulfur-based autotrophic denitrification sludge and anaerobic ammonia oxidation sludge.

2. The method according to claim 1, characterized in that: In step 1, the volume ratio of the wastewater treated by nitrification and carbonization is 1:1-1.2:

1.

3. The method according to claim 1, characterized in that: In step 1, the sludge concentration of the nitrification unit is 3000-5000 mg / L, the dissolved oxygen concentration is controlled at 1.0-3.0 mg / L through aeration, the aeration time is 4-8 hours, and the sludge age is 10-15 days by discharging sludge every day; the sludge concentration of the carbonization unit is 2000-3500 mg / L, the dissolved oxygen concentration is controlled at 0.5-1.0 mg / L through aeration, the aeration time is 0.5-2 hours, and the sludge age is within 5 days by discharging sludge every day.

4. The method according to claim 1, characterized in that: In step 2, the dissolved oxygen in the mixed water is removed by nitrogen aeration to make the DO less than 0.2 mg / L.

5. The method according to claim 1, characterized in that: In step three, the sulfur and carbonate minerals are cleaned of impurities on the surface with dilute hydrochloric acid before use, and then rinsed with clean water until neutral and then dried.

6. The method according to claim 1, characterized in that: In step three, the sulfur-based autotrophic denitrification sludge and the anaerobic ammonium oxidation sludge are poured into the upflow anaerobic bioreactor, and the sewage containing 30m / L ammonia nitrogen and 40mg / L nitrite nitrogen is prepared. After circulating in the upflow anaerobic biofilter reactor for 4 days, the new sewage is replaced. The whole process is repeated 10 times, and it is considered that the sulfur-based autotrophic denitrification sludge and the anaerobic ammonium oxidation sludge are inoculated successfully.

7. The method according to claim 1, characterized in that: In step three, the carbonate minerals include one or more combinations of limestone, dolomite, siderite and magnesite.

8. The method according to claim 1, characterized in that: In step three, the source of the sulfur-based autotrophic denitrification sludge includes one or a mixture of autotrophic sludge, heterotrophic sludge, and anaerobic sludge; the anaerobic ammonium oxidation sludge includes one or a mixture of anaerobic ammonium oxidation granular sludge and anaerobic ammonium oxidation flocculent sludge.

9. The method according to claim 6, characterized in that: The flow rate of sewage circulating in the upflow anaerobic biofilter reactor is 10 mL / min.

10. The method according to claim 1, characterized in that: In step 3, the particle shape of the sulfur includes one or a combination of spherical, cylindrical, and flaky.

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