PD / A stable denitrification device and method based on continuous carbon source starvation

Abstract

The invention discloses a PD / A stable denitrification device and method based on continuous carbon source starvation, and belongs to the technical field of sewage biological denitrification treatment.The device is characterized in that a moving bed bio-membrane reactor serves as a core reaction unit, the filler filling rate is controlled to be 10-30%, and the reactor is used for loading denitrification functional microorganisms needed by PD / A; the denitrification device operates in a continuous flow mode, the carbon-nitrogen ratio is 3-4, and the hydraulic retention time is 3-6 hours; and then maintaining the metabolic activity of PDB at a lower level by maintaining a continuous carbon source starvation condition, thereby reducing the activity difference between PDB and anaerobic ammonium oxidation bacteria, forming synergistic cooperation among florae, and realizing stable denitrification of a PD / A system. According to the PD / A stable denitrification device and method based on continuous carbon source starvation, direct starting and long-term stable operation of a PD / A reaction system can be achieved within a short time without an SBR pre-enrichment process or a complex control means.

Description

Technical Field

[0001] This invention relates to the field of biological nitrogen removal technology for wastewater, and in particular to a PD / A stable nitrogen removal device and method based on continuous carbon source starvation. Background Technology

[0002] Traditional biological nitrogen removal mainly relies on the nitrification-denitrification process, using autotrophic nitrifying bacteria to remove ammonia nitrogen (NH4+). + -N) is oxidized to nitrate (NO2) - Anaerobic ammonia oxidation (NAO) involves the resorption of nitrogen by heterotrophic denitrifying bacteria using organic carbon sources. However, this process requires high dissolved oxygen and an external carbon source, resulting in high energy consumption and cost, which is detrimental to the low-carbon and energy-saving aspects of wastewater treatment. In contrast, anaerobic ammonia oxidation (AAO)... Anammox This is a highly efficient autotrophic nitrogen removal pathway that does not require aeration or external carbon sources, and can directly remove NH4+. + -N and NO2 - The conversion of nitrogen (NO-) to nitrogen (N2) significantly reduces energy consumption and carbon emissions. Based on this mechanism, the partial nitrification-anaerobic ammonia oxidation (PN / A) process is considered a core nitrogen removal technology for next-generation wastewater treatment plants. However, under the low ammonia nitrogen and low temperature conditions of mainstream wastewater, nitrite-oxidizing bacteria (NOB) are difficult to effectively inhibit, leading to increased NO2 emissions. - -N is easily further oxidized to NO3. - -N, thus weakening Anammox The reaction limits the denitrification efficiency of the PN / A process.

[0003] To overcome the limitation of NOB suppression in the PN / A process, researchers proposed a partial denitrification-anaerobic ammonium oxidation (PD / A) process. This process utilizes heterotrophic denitrifying bacteria to oxidize NO3-. - -N is partially reduced to NO2. - -N, then by Anammox bacteria will produce NO2 - -N and NH4 + -N is converted to N2, achieving stable NO2. - -N supply and efficient nitrogen removal. Compared to PN / A, PD / A does not require strict NOB suppression, is more adaptable to temperature and influent conditions, and has broader mainstream application prospects. However, the stable operation of PD / A is limited by the reactor operating mode and control mechanism. Current research mainly focuses on sequencing batch reactors (SBRs), relying on periodic "feast-famine" conditions for enrichment. Thauera Some denitrifying bacteria (PDB) obtain higher NO2. -While the carbon accumulation rate is significant, municipal wastewater treatment plants mostly adopt continuous flow (CFR) mode, which differs significantly from SBR in carbon supply methods and F / M ratio distribution. Existing continuous flow PD / A systems largely rely on SBR pre-enriched sludge for startup, and achieving stable establishment and long-term maintenance of PD / A under low-carbon-source continuous flow conditions still faces challenges.

[0004] From a metabolic perspective, NO2 - The accumulation of -N during partial denitrification is controlled by both microbial community structure and substrate availability. Studies have shown that... Thauera Although denitrifying bacteria of this genus carry the nosZ gene encoding N2O reductase, its expression can be suppressed under certain conditions, resulting in "short-range denitrification" and promoting NO2 production. - Accumulation of -N. In addition, moderate amounts of NO3. - -N residues can inhibit Nir(NO2) - The synthesis of α-N reductase further promotes NO2 synthesis. - -N enrichment. Carbon source limitation is considered a key driver for initiating the PD process, and periodic carbon source supply (Feast–Famine) can upregulate it. NarG , NarI Wait for NO3 - -N reducing gene expression promotes NO2 - -N generation. However, when this strategy is applied to mainstream engineering systems (such as AAO or oxidation ditches), the operating mode changes from a periodic "Feast–Famine" state to a long-term "Famine" state, which may lead to a fundamental change in the microbial metabolic regulation mechanism, thereby affecting NO2. - -N accumulation and PD stability.

[0005] Therefore, it is urgent to elucidate the stable operation mechanism of the PD / A process under continuous carbon source starvation conditions, reveal the coupling law between carbon metabolism, electron transfer and nitrogen conversion under different operating modes, and provide theoretical guidance and process support for the engineering application of continuous flow PD / A systems. Summary of the Invention

[0006] The purpose of this invention is to provide a PD / A stable denitrification device and method based on continuous carbon source starvation. It can achieve direct start-up and long-term stable operation of the PD / A reaction system in a short time without the need for SBR pre-enrichment process or complex control means. The method has the characteristics of fast start-up, low energy consumption, stable operation and strong resistance to disturbance, and is suitable for mainstream wastewater treatment conditions such as low C / N and short HRT.

[0007] To achieve the above objectives, the present invention provides a PD / A stable denitrification device based on continuous carbon source starvation, including a moving bed biofilm reactor and a water bath circulation device. The reactor has an inlet and a sampling port at the top and an overflow port on the side wall. The outer layer of the reactor is provided with a heat insulation layer. A propeller and a No. 1 real-time thermometer are installed on the reactor, and the reactor is connected to the water bath circulation device through a connecting pipe.

[0008] Preferably, the reactor is spherical, the insulation layer is a water bath jacket, the water bath circulation device is connected to the water bath jacket, and the inlet is connected to a nitrogen source inlet pipe and a carbon source inlet pipe. Both the nitrogen source inlet pipe and the carbon source inlet pipe are equipped with peristaltic pumps, which are connected to a time-space switch.

[0009] This invention also provides a PD / A stable denitrification method based on continuous carbon source starvation, employing the aforementioned PD / A stable denitrification device based on continuous carbon source starvation, comprising the following steps: S1. Prepare a moving bed biofilm reactor and introduce substrate and carbon source into the reactor in a continuous flow mode. S2. Collect influent and effluent samples daily, measure substrate concentration, monitor and calculate data throughout the reactor operation process, and evaluate the reactor's denitrification effect. The partial denitrification activity and anaerobic ammonia nitrogen activity were measured twice or more during S3 and 15-20 days to evaluate the synergistic metabolic denitrification effect of PDB and AnAOB. S4. The abundance of functional microbial communities in sludge was analyzed using the Illumina MiSeq sequencing platform to test 16S rRNA sequences, and typical partial denitrifying bacteria were assessed. Thauera The enrichment effect of anaerobic ammonia oxidizing bacteria Candidatus _Brocadia and Candidatus _Jettenia Enrichment effect; S5. Metatranscriptional assays were used to analyze the expression levels of genes related to nitrogen metabolism, carbon metabolism, and electron transport, and to assess the essential impact of PDB and AnAOB on nitrogen metabolism, carbon metabolism, and electron transport mechanisms under continuous operation.

[0010] Preferably, in S1, the reactor filling rate is 10-30%, and the packing material in the reactor is K3 / K5 type packing with a surface area of ​​500-860. .

[0011] Preferably, in S1, the substrate is NH4. + -N and NO3 - -N,NH4 + -N concentration is 15-25 NO3 - -N concentration is 15-25 The carbon source is sodium acetate.

[0012] Preferably, in S1, the carbon (as COD) / NO3 ratio of the carbon source is... - -N is 3-4, and the hydraulic residence time is 3-6h.

[0013] Furthermore, the TN concentration in the influent is 30-50%. .

[0014] Preferably, in step S1, the internal temperature of the reactor is maintained at 29.5-30.5°C. .

[0015] Furthermore, in S2, the denitrification effect of the reactor is as follows: The TN concentration in the effluent is 2.00-9.80. ; Total nitrogen removal rate is 75-90%; The total nitrogen removal load is 0.19-0.36. .

[0016] Preferably, in S3, the nitrate reduction rate is used. NO3 - -N and nitrite formation rate NO2 - -N reaction partially nitration activity, using NH4 + -N consumption rate NH4 + -N reaction anaerobic ammonia nitrogen oxidation activity.

[0017] Preferably, in S3, NO3 - -N、 NO2 - -N and NH4 + -N are respectively: NO3 - -N is 1514.78-3611.43 ; NO2 - -N is 962.45-2301.59 ; NH4 + -N is 1053.77-1864.80 .

[0018] Preferably, in S4, Thauera The abundance ranged from 8.03% to 38.66%. JetteniaAbundance ranged from 0.36% to 54.21%; Brocadia The abundance ranged from 28.38% to 41.98%.

[0019] This method inhibits electron donation by regulating the continuous input of electron donors and acceptors. Thauera Denitrifying bacteria Nir / Nor / Nos Gene expression, stabilizing NO2 - -N accumulation, and promote Brocadia genus Anammox Bacterial-associated genes ( Hdh , Hzs Enrichment of PD / A pathways, thereby achieving long-term stability of PD / A pathways.

[0020] Therefore, the present invention employs the above-mentioned PD / A stable denitrification device and method based on continuous carbon source starvation, which has the following beneficial effects: (1) Rapid start-up and high nitrogen removal efficiency: The PD / A process can be started up in <90 days, with a total nitrogen removal rate of >80% and a nitrogen removal rate of >1200. During long-term operation, the total nitrogen removal rate remained at >85%, and the contribution rate of anaerobic ammonia oxidation was >90%, demonstrating stable and efficient nitrogen removal performance.

[0021] (2) No need for pre-concentration and complex control: The start-up process does not require pre-concentration by a sequencing batch reactor, nor does it require nitrite supplementation or aeration control; the process is simple and easy to connect with existing municipal wastewater continuous flow treatment units (such as AAO, oxidation ditch).

[0022] (3) Strong resistance to disturbance and recovery ability: After experiencing starvation disturbance, the system can quickly (recovery time <20d) restore the total nitrogen removal rate. It recovered to 80% and eventually returned to the pre-perturbation level, demonstrating good robustness.

[0023] (4) Prominent characteristics of microbial community and metabolic regulation: Under continuous flow operation mode, Thauera The function tends towards partial denitrification, downstream Nir / Nor / Nos Suppressed gene expression favors NO2 - Stable accumulation of -N; Anammox Related genes ( Hdh , Hzs The high abundance indicates that anaerobic ammonia oxidation activity is dominant; the electron flow distribution is stable, forming a system based on... Anammox A highly efficient nitrogen removal pathway with [the following] as its core.

[0024] (5) Adaptable to mainstream wastewater treatment conditions: The PD / A process in continuous flow mode can operate at low C / N ratios. 3.0), short HRT ( It can operate stably under near-mainstream conditions such as 3h, and can be directly embedded into mainstream processes such as AAO or oxidation ditch without changing the existing continuous flow process structure, so as to achieve energy-saving, low-carbon and efficient denitrification treatment, showing good potential for engineering promotion.

[0025] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0026] Figure 1 These are device diagrams of Embodiment 1 and Comparative Example 1 of the present invention, which describe a PD / A stable denitrification device and method based on continuous carbon source starvation. Figure 2 This invention relates to the changes in denitrification performance during the start-up and operation phases of Example 1 and Comparative Example 1 of a PD / A stable denitrification device and method based on continuous carbon source starvation according to the present invention. Figure 3 This invention relates to the changes in biofilm thickness and color in Example 1 and Comparative Example 1 of a PD / A stable denitrification device and method based on continuous carbon source starvation. Figure 4 This invention provides a comparison of PD and Anammox activities in Example 1 and Comparative Example 1 of a PD / A stable denitrification device and method based on continuous carbon source starvation, as well as the denitrification contributions of the two pathways. Figure 5 The accompanying figures show the differences in abundance and contribution of key functional genes in Example 1 and Comparative Example 1 of the present invention, which describes a PD / A stable denitrification device and method based on continuous carbon source starvation. Figure 6 This invention relates to the difference in expression levels of electron transport-related genes between Example 1 and Comparative Example 1 of a PD / A stable denitrification device and method based on continuous carbon source starvation.

[0027] Figure Labels 1. Peristaltic pump; 2. No. 1 real-time thermometer; 3. Propeller; 4. Time-space switch; 5. Sampling port; 6. No. 2 real-time thermometer; 7. Overflow port; 8. Packing material; 9. Water bath circulation device; 10. Water bath sleeve; 11. Carbon source inlet pipe; 12. Nitrogen source inlet pipe. Detailed Implementation

[0028] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0029] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0030] Example 1 like Figure 1 As shown, this invention provides a PDA-based stable denitrification device based on continuous carbon source starvation, comprising a moving bed biofilm reactor and a water bath circulation device 9. The reactor is spherical with a filling rate of 10-30%. The packing material 8 in the reactor is K3 / K5 type packing material 8 with a surface area of ​​500-860. The reactor has an inlet and a sampling port 5 at the top. Basic parameters are measured by taking samples at the sampling port 5. A nitrogen source inlet pipe 12 and a carbon source inlet pipe 11 are connected to the inlet, and both are equipped with peristaltic pumps 1. These pumps transport the substrate and carbon source into the reactor. The substrate enters the reactor through the nitrogen source inlet pipe 12, and the carbon source enters through the carbon source inlet pipe 11. An overflow port 7 is located on the side wall of the reactor, through which the effluent is discharged. No staged water intake, aeration, or reaction switching is implemented during operation.

[0031] The reactor is equipped with an outer insulation layer, which is a water bath jacket 10. A propeller 3 and a first real-time thermometer 2 are installed on the reactor. The reactor is connected to a water bath circulation device 9 via a connecting pipe. The water bath circulation device 9 is connected to the water bath jacket 10 and adopts a structure based on existing technology. By connecting to the water bath jacket 10, the temperature in the reactor is controlled to be maintained at 29.5-30.5°C. Furthermore, a second real-time thermometer 6 is installed in the water bath circulation device 9 to monitor the temperature within the device. The outer wall of the reactor is also wrapped with aluminum foil to maintain a dark environment.

[0032] This invention also provides a PD / A stable denitrification method based on continuous carbon source starvation, employing the aforementioned PD / A stable denitrification device based on continuous carbon source starvation, comprising the following steps: (1) Start-up and operating parameters: The laboratory wastewater used during reactor operation was artificially prepared nitrogen-containing simulated wastewater, with ammonia nitrogen (NH4) content of 100%. + -N) is mainly added in the form of ammonium chloride, while nitrate nitrogen (NO3) is added in the form of ammonium chloride. - Nitrogen (TN) is mainly added in the form of potassium nitrate, COD is added in the form of anhydrous sodium acetate, sodium bicarbonate is used to adjust the pH, and trace element solution provides metal ions and inorganic salts. During the start-up phase, the influent nitrogen concentration is TN at 30-50%. COD / NO3 - The -N ratio is 3.5-4, and the hydraulic retention time (HRT) is 5-6 hours. The water supply mode is always continuous. Specific operating parameters are shown in Table 1.

[0033] Table 1 Reactor operating parameters

[0034] (2) Denitrification performance and biofilm characteristics: Total nitrogen removal rate (NRE) of the continuous flow reactor after startup and stabilization. 80% nitrogen removal rate (NRR) 1200 The PD / A system was successfully established, with the anaerobic ammonia oxidation process contributing >60% to nitrogen removal. After the system recovered from starvation disturbances, nitrogen removal efficiency (NRE) recovered and remained above 85% within 15-20 days, while nitrogen resorption rate (NRR) was controlled at >1200. With subsequent reductions in C / N and shortening of HRT, R C After a brief period of fluctuation, the operating status eventually stabilized, with NRE exceeding 80%, and the nitrogen removal contribution of the anaerobic ammonia oxidation pathway exceeding 95% (see...). Figure 2 (b) Figure 2 (d) in Figure 2 (f) in the middle.

[0035] Biofilm thickness initially approximately 800 It gradually decreased to 293.15 on day 50. 76.15 It then resumed growth, reaching 708.50 on the 200th day. 87.34 The color gradually changes from red to grayish-yellow, and finally stabilizes at reddish-brown, indicating a continuous enrichment of anaerobic ammonia-oxidizing bacteria (such as...). Figure 3 (a) Figure 3 (b) Figure 3 (as shown in (d)).

[0036] (3) Activity detection (SAA / SPDA): by Figure 4 (b) and Figure 4As shown in (d), SPDA is initially relatively high. NO3 - -N=8390.93 120.45 ; NO2 - -N=5344.29 87.90 After 80 days, it dropped to below the control group 1 R. S SPDA level; SAA decreased less during the initial phase and stabilized at 584.44 by day 80. 9.44 After the hunger disturbance, NH4 + -N max restored to 456.69 11.32 This demonstrates strong system resilience.

[0037] Furthermore, with subsequent adjustments to operating parameters (C / N and HRT), SPDA remained at a relatively stable level. NO3 - -N=1576.29 64.28 ; NO2 - -N=1243.89 225.11 However, SAA gradually increased to 1446.34. 331.61 In R C There exists a balance in the system, namely, a small difference between SPDA and SAA, which maintains a stable distribution of electron acceptors and NO2. - -N Supply and demand balance.

[0038] (4) Functional microbial community structure: The dominant microbial community is Thauera and Brocadia After the startup results (R) C - ), Thauera The relative abundance was approximately 66.54%. Brocadia and Jettenia They accounted for 18.62% and 0.24% respectively. After experiencing a 32-day starvation perturbation, the system recovered for 16 days. Thauera The relative abundance decreased to 26.25%, at which point... Brocadia and Jettenia The relative abundances were 15.98% and 46.08%, respectively. After adjusting the C / N ratio to 3 and the HRT to 3 hours, the system stabilized. At this point, the abundance in R... C - , Thauera and Brocadia The relative abundance of both changed, with the former decreasing to 10.21% and the latter increasing to 28.38%, reaching R... C In stage V, both bacteria remain at the same level. C The relative abundance of key functional genera in the system is shown in the table below: Table 2. Relative abundance of functional bacterial genera

[0039] Key functional gene expression: Metabolic gene analysis showed that ( Figure 5 (a)-(b) in the middle: NarGHI + NapAB (NO3 - -N reduced gene): R C The cumulative abundance is 921.08. 378.36; NirK In R C The expression in R was higher than that in Comparative Example 1. S The system, and NirS , NorB , NorC Low expression (NO2) - -N reduced gene); Hzs and Hdh (Key genes for anaerobic ammonium oxidation) in R C The abundance was 2180.35. 870.93, higher than R S (682.01 949.56). R C The reactor exhibits the following characteristics: Brocadia With its dominant functional characteristics, this bacterium not only participates in anaerobic ammonia oxidation (AMO) Hdh , Hzs ), and also NO3 - -N restores related information NarGHI and NapA Genetic contribution was significant. The continuous influent mode maintained a low and stable F / M ratio and carbon source supply, thereby inhibiting... Thauera Its complete denitrification activity promotes the synergistic effect of partial denitrification and anaerobic ammonium oxidation. R C In the system ( NarGHI + NapAB ) / ( NirSK The stable and relatively high electron partition ratio (3.1–3.9) indicates that the system maintains a predominantly partial denitrification electron partitioning pattern over a long period. Anammox Metabolic matching is highly accurate. Under these conditions... Brocadia It exhibits a certain degree of metabolic plasticity and participates in NO3. --N reduction process, thereby optimizing PD and Anammox Electron flow distribution between organisms. Overall, the continuous flow operation mode facilitated a balanced microbial community structure, achieving stable coupling of the PD / A pathway and efficient denitrification performance.

[0040] Electron transport and energy metabolism: The electron transport chain exhibits a stable, low-energy-consuming "Complex I→Cyt c→ Hzs "Dominant pathway, Hzs The expression level was 1.78 times that of Comparative Example 1; Complex , Nir , Nor , Nos The expression of downstream genes is low, reflecting the continuous flow pattern. Anammox The dominant electron flow allocation strategy. ATP synthase expression remained stable without significant fluctuations. Figure 6 (a) in the middle.

[0041] Comparative Example 1 Sequential batch PD / A process (R S Startup and stable operation of ) like Figure 1 As shown, this comparative example uses the same reactor structure and influent water quality as Example 1, only the operating mode is changed to a sequencing batch reactor (SBR). The influent and effluent times and the operating time are controlled by the peristaltic pump 1 and the propeller 3 through the time-space switch 4. The operating cycle is divided into five steps: nitrogen inlet (10 min), oxygen consumption (5 min), addition of external carbon source (4 min), PD / A reaction (151-331 min), and drainage (10 min). The effluent exits from the effluent hole at the bottom of the reactor, the drainage ratio is 100%, and the effluent hole is connected to the effluent pipe, on which the peristaltic pump 1 is installed.

[0042] Start-up and operating parameters: C / N ratio gradually increased from 3.5 to 4.0, HRT maintained for 6 hours; NH4 increased from day 59. + -N concentration up to 25 Reduce NO3 - -N=5 On day 183, NO2 was added in stages. - -N is used for recovery; see Table 3 for specific operating parameters.

[0043] Table 3 R S Running parameters

[0044] Denitrification performance and biological characteristics: The SBR system was successfully started up on day 58, at which point the nitrogen removal efficiency (NRE) was approximately 72.58. 4.27%, NRR was 833.22 44.52 ( Figure 2 (a) Figure 2 (c) Figure 2 In (e) of this step, the nitrogen removal contribution of the anaerobic ammonia oxidation process is 82.82%. 7.11%. Subsequently, adjustments to the influent nitrogen concentration led to a decline in denitrification efficiency; by day 82, NRE and NRR had decreased to 57.24%. 0.74% and 651.86 4.24 Recovery after subsequent starvation disturbances was slow, with NRE remaining around 20% for an extended period, failing to return to pre-starvation levels. It wasn't until day 183 that NO2 was detected. - -N plus restoration to 66.50 The NRR increased to 853.83, reaching 11.65%. 150.35 Compared to R S R C The absence of exogenous nitrite induction and the rapid recovery of denitrification efficiency indicate that R C It is more stable and robust. With adjustments to C / N and HRT, R... S At day 230, NRE and NRR stabilized at 67.58. 2.75% and 1158.51 47.10 At this point, the nitrogen removal contribution of the anaerobic ammonium oxidation process is 66.12%. 2.81%, compared to R C Its anaerobic ammonia oxidation process contributes poorly to nitrogen removal, indicating that R C It is more conducive to balancing the PD / A system.

[0045] Biofilm thickness increased from an initial 800 It dropped to 644.25 185.41 (Day 50), then gradually increased in thickness to 1045.95. 148.02 (Day 200). Between days 85 and 150, the color changes from red to white, only in NO2. - Adding -N restores the red color, indicating that AnAOB failed to maintain a stable state in the system. Figure 3 (a)-(c)).

[0046] (3) SAA and SPDA: by Figure 4 From (c)-(d) in the diagram, we can see that SPDA in R S China's rate remains higher than SAA's: NO3- -N=4509.13 373.53 , NO2 - -N=3135.67 407.84 SAA levels decreased significantly, reaching only 534.94 by day 80. 21.44 After the hunger disturbance, it only recovered to 71.2%. 5.37 ( Figure 4 (cd)). Long-term imbalance of SPDA-SAA leads to NO2 - -N supply and demand mismatch and enhanced full denitrification.

[0047] (4) Abundance of functional bacteria: In R S In the reactor, the dominant functional microbial community is mainly... Thauera and Brocadia Meanwhile, in the later stages Jettenia The relative abundance of [a substance] increased significantly. In R [a specific region / organization]... S - , Thauera and Brocadia Their relative abundances were similar, accounting for 28.27% and 27.51% respectively. Jettenia and Azoarcus They accounted for 31.66% and 5.17% respectively. When the system recovered to 150 days after the starvation perturbation (R... S - ), Thauera Its abundance rapidly increased to 64.73%, becoming the absolutely dominant bacterium, indicating that the system at this stage was dominated by heterotrophic denitrification. Brocadia and Jettenia The abundance of NO2 dropped sharply to 2.78% and 0.14%. - -N supplementary period (R S - ), Thauera It remains at a relatively high level (58.47%), but Brocadia The abundance of [a specific substance] increased significantly to 25.95%, indicating that the anaerobic ammonium oxidation pathway gradually recovered. During the system's stable phase (R...), [the following information is missing from the original text]. S -V), Thauera The abundance of decreased significantly to 3.63%, while Brocadia and Jettenia They rose to 31.58% and 60.31% respectively. This change indicates that R S The system gradually shifted from a heterotrophic denitrification-dominated state to a stable operating state dominated by PD / A coupled nitrogen removal, in which... Brocadia and JetteniaThe anaerobic ammonium oxidation activity of the system was synergistically maintained under low C / N ratio and short HRT conditions. S The relative abundance of key functional genera in the system is shown in the table below: Table 4. Relative abundance of functional bacterial genera

[0048] (5) Functional gene expression: Thauera As the main functional bacteria, it exhibits strong denitrification genes ( NarH , NarI , NapB , NirS , NorB , NorC , NosZ The expression indicates that it possesses significant full denitrification potential under the periodic Feast–Famine operating mode. Due to the system operation... COD The TN ratio is higher than the theoretical requirement (1.70–2.78). Thauera Using excess organic carbon to control NO3 - -N is gradually reduced to N2, resulting in NO2 produced by the PD pathway. - -N is further consumed, resulting in insufficient electron acceptors for the anaerobic ammonium oxidation reaction; Hdh and Hzs Abundance lower than R C ,show Anammox Metabolism is inhibited; NarGHI + NapAB ) / NirSK The ratio fluctuated significantly between 1.5 and 4.5, reflecting the instability of electron donor / acceptor allocation.

[0049] (6) Electron transport: R S Complex in the system Cyt c Nir / Nor / Nos Full-chain electron transport is active, and the expression level of ATP synthase is higher than that of R. C Approximately 1.7 times higher, forming a "high-flux, high-consumption" electron flow characteristic. NO2 - The system experiences a short-term boost during N-N replenishment, but once this is stopped, ATP levels drop sharply and performance collapses due to limited electron acceptors.

[0050] Therefore, the present invention adopts the above-mentioned PD / A stable denitrification device and method based on continuous carbon source starvation, which can achieve direct start-up and long-term stable operation of the PD / A reaction system in a short time without the need for SBR pre-enrichment process or complex control means. The method has the characteristics of fast start-up, low energy consumption, stable operation and strong resistance to disturbance, and is suitable for mainstream wastewater treatment conditions such as low C / N and short HRT.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A PD / A stable denitrification device based on continuous carbon source starvation, characterized in that: It includes a moving bed biofilm reactor and a water bath circulation device. The reactor has an inlet and a sampling port at the top and an overflow port on the side wall. The outer layer of the reactor is equipped with a heat insulation layer. The reactor is equipped with a propeller and a No. 1 real-time thermometer. The reactor is connected to the water bath circulation device through a connecting pipe.

2. The PD / A stable denitrification device based on continuous carbon source starvation according to claim 1, characterized in that: The reactor is spherical, with a water bath jacket as the insulation layer. The water bath circulation device is connected to the water bath jacket. A nitrogen source inlet pipe and a carbon source inlet pipe are connected to the water inlet. Both the nitrogen source inlet pipe and the carbon source inlet pipe are equipped with peristaltic pumps, which are connected to a time-space switch.

3. A PD / A stable denitrification method based on continuous carbon source starvation, employing the PD / A stable denitrification device based on continuous carbon source starvation as described in any one of claims 1-2, characterized in that: Includes the following steps: S1. Prepare a moving bed biofilm reactor and introduce substrate and carbon source into the reactor in a continuous flow mode. S2. Collect influent and effluent samples daily, measure substrate concentration, monitor and calculate data throughout the reactor operation process, and evaluate the reactor's denitrification effect. The partial denitrification activity and anaerobic ammonia nitrogen activity were measured twice or more during S3 and 15-20 days to evaluate the synergistic metabolic denitrification effect of PDB and AnAOB. S4. The abundance of functional microbial communities in sludge was analyzed using the Illumina MiSeq sequencing platform to test 16S rRNA sequences, and typical partial denitrifying bacteria were assessed. Thauera The enrichment effect of the anaerobic ammonia-oxidizing bacteria Candidatus _Brocadia and Candidatus _Jettenia Enrichment effect; S5. Metatranscriptional assays were used to analyze the expression levels of genes related to nitrogen metabolism, carbon metabolism, and electron transport, and to assess the essential impact of PDB and AnAOB on nitrogen metabolism, carbon metabolism, and electron transport mechanisms under continuous operation.

4. The PD / A stable denitrification method based on continuous carbon source starvation according to claim 3, characterized in that: In S1, the reactor filling rate is 10-30%, and the packing material is K3 / K5 type packing with a surface area of ​​500-860. .

5. The PD / A stable denitrification method based on continuous carbon source starvation according to claim 3, characterized in that: In S1, the substrate is NH4. + -N and NO3 - -N,NH4 + -N concentration is 15-25 NO3 - -N concentration is 15-25 The carbon source is sodium acetate.

6. The PD / A stable denitrification method based on continuous carbon source starvation according to claim 3, characterized in that: In S1, the carbon / NO3 in the carbon source - -N is 3-4, and the hydraulic residence time is 3-6h.

7. The PD / A stable denitrification method based on continuous carbon source starvation according to claim 3, characterized in that: In S1, the internal temperature of the reactor is maintained at 29.5-30.5°C. .

8. The PD / A stable denitrification method based on continuous carbon source starvation according to claim 3, characterized in that: In S3, the nitrate reduction rate is used. NO3 - -N and nitrite formation rate NO2 - -N reaction partially nitration activity, using NH4 + -N consumption rate NH4 + -N reaction anaerobic ammonia nitrogen oxidation activity.

9. A PD / A stable denitrification method based on continuous carbon source starvation according to claim 8, characterized in that: In S3, NO3 - -N、 NO2 - -N and NH4 + -N are respectively: NO3 - -N is 1514.78-3611.43 ; NO2 - -N is 962.45-2301.59 ; NH4 + -N is 1053.77-1864.80 .

10. A PD / A stable denitrification method based on continuous carbon source starvation according to claim 3, characterized in that: In S4, Thauera The abundance ranged from 8.03% to 38.66%. Jettenia Abundance ranged from 0.36% to 54.21%; Brocadia The abundance ranged from 28.38% to 41.98%.

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