A wastewater energy-saving and efficient denitrification and carbon reduction treatment system and process

Abstract

The present invention provides a wastewater energy-saving and efficient denitrification and carbon reduction treatment system and process, belonging to the field of water treatment technology. The system includes a regulating tank, a denitrification and carbon reduction tank, a short-cut denitrification tank, and a secondary sedimentation tank connected in series. The denitrification and carbon reduction tank can simultaneously carry out short-cut nitrification and denitrification reactions and carbon reduction reactions. A single tank body can achieve more than 70% total nitrogen removal and more than 85% COD removal in the influent. Using the above system to treat wastewater, the final effluent can achieve a denitrification efficiency of more than 90% and a COD removal rate of more than 90%. The wastewater energy-saving and efficient denitrification and carbon reduction treatment system and process of the present invention has a simple process flow, is easy and convenient to operate, occupies a small area, effectively saves operating costs and energy consumption, and can be applied to various water treatment fields that require total nitrogen removal, such as industrial wastewater, domestic sewage, commercial sewage, and aquaculture sewage.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and in particular relates to a wastewater energy-saving and efficient denitrification and carbon reduction treatment system and process. Background Art

[0002] Nitrogen in water mainly comes from the metabolism and corruption of organisms, as well as the discharge of industrial wastewater, domestic sewage, commercial sewage, and the loss of nitrogen fertilizers. There are four forms of nitrogen in sewage: organic nitrogen, ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen.

[0003] Currently, the use of activated sludge to remove total nitrogen is extremely widespread and is used to treat the total nitrogen contained in common water bodies such as industrial wastewater, domestic sewage, commercial sewage and aquaculture sewage.

[0004] For example, Harbin Institute of Technology's invention patent application number 202210380178.8 discloses an integrated device and method for the simultaneous ecological treatment of domestic sewage and sludge. The device consists of interconnected anaerobic tanks, sludge reduction and short-cut denitrification tanks, and aerobic tanks. It uses different tanks to carry out nitrification and denitrification to treat the total nitrogen in domestic sewage.

[0005] For example, the invention patent application number 201910865366.8 of the Zhejiang Academy of Agricultural Sciences discloses an anoxic-aerobic-algae three-stage circulation system for treating aquaculture wastewater, in which ammonia nitrogen in aquaculture wastewater is treated by nitrification and denitrification in different tanks such as aerobic tanks and anaerobic tanks respectively in combination with activated sludge.

[0006] Coking wastewater, generated during the coal coking process, contains more pollutants than domestic sewage and aquaculture wastewater, which are more complex. These pollutants include phenols, polycyclic aromatic compounds, and heterocyclic compounds containing nitrogen, oxygen, and sulfur. It is a typical example of industrial wastewater characterized by complex composition, high toxicity, and difficulty in degradation. With increasing environmental regulation of wastewater treatment, national emission standards for wastewater treatment plants are becoming increasingly stringent. The "Coking Chemical Industry Pollutant Emission Standard" (GB16171-2012), implemented by the Ministry of Environmental Protection in 2012, requires that the emission limits for ammonia nitrogen and total nitrogen be reduced from the original 15 mg / L and 30 mg / L to 10 mg / L and 20 mg / L, respectively. These higher emission standards place greater demands on the development of denitrification technologies for coking wastewater, making denitrification a key challenge in the coking wastewater treatment industry.

[0007] The denitrification technology of coking wastewater mainly includes physical method and biological method. Biological denitrification is widely used due to its advantages of economy, effectiveness, pollution-free transfer, and simple and easy operation. Traditional biological denitrification, namely nitrification and denitrification technology, refers to the process in which nitrogen-containing compounds in sewage are converted into nitrogen gas through a series of biochemical reactions such as ammoniation reaction, nitrification reaction and denitrification reaction of microorganisms. At present, the biological denitrification processes widely used in coking wastewater treatment plants include A / O, A 2 / O and its deformation process A / O 2 , O / A / O, etc., based on the principle of "nitrification-denitrification." Some water plants have added deep denitrification processes, such as biofilters, to meet emission standards during upgrades. The addition of deep denitrification processes and their modifications not only lengthen the process flow but also increase floor space, operating costs, and energy consumption. Furthermore, the denitrification efficiency of A / O and its variations is limited by the reflux ratio, creating a bottleneck in improving denitrification effectiveness.

[0008] In recent years, new denitrification technologies have been developed, such as the SBR process. While its advantage lies in shortening the process flow, it is also challenging to operate due to its stringent operational requirements. Furthermore, it still operates in a traditional denitrification mode, and the treatment cycle has not been shortened. Therefore, the industry urgently needs a simple-to-operate wastewater treatment system and denitrification method that breaks through the traditional denitrification model, shortens the process flow and reaction cycle, improves denitrification efficiency, and reduces operating costs and energy consumption. Summary of the Invention

[0009] In response to the above problems, the present invention proposes an energy-saving and efficient denitrification and carbon reduction treatment system and process for coking wastewater, which has a shorter process flow, lower construction cost, and higher denitrification and carbon reduction efficiency than previous conventional processes.

[0010] To achieve the above object, the technical solution adopted by the present invention is:

[0011] A wastewater energy-saving and high-efficiency denitrification and carbon reduction treatment system, comprising a denitrification and carbon reduction tank;

[0012] The dissolved oxygen concentration in the denitrification and carbon reduction tank is 0.4-1.5 mg / L;

[0013] The denitrification and carbon reduction pool is equipped with fillers and a high-efficiency denitrification and carbon reduction sludge system, which can simultaneously carry out short-term nitrification and denitrification reactions and carbon reduction reactions under stable and continuous aeration conditions.

[0014] Furthermore, when continuous water inflow is adopted, the wastewater energy-saving and efficient denitrification and carbon reduction treatment system further comprises a regulating tank, a first sedimentation tank, a short-cut denitrification tank and a second sedimentation tank connected in series in sequence;

[0015] The denitrification and carbon reduction tank is set between the regulating tank and the first sedimentation tank;

[0016] The first sedimentation tank is connected to the denitrification and carbon reduction tank, and the second sedimentation tank is connected to the short-cut denitrification tank through sludge return pipes.

[0017] The second sedimentation tank is connected to the denitrification and carbon reduction tank through a supernatant return pipe;

[0018] When intermittent water inflow is adopted, the wastewater energy-saving and high-efficiency denitrification and carbon reduction treatment system further comprises a regulating tank, a short-cut denitrification tank and a secondary sedimentation tank connected in series in sequence;

[0019] The denitrification and carbon reduction tank is set between the regulating tank and the short-cut denitrification tank;

[0020] The secondary sedimentation tank is connected to the short-cut denitrification tank through a sludge return pipe;

[0021] The secondary sedimentation tank is connected to the denitrification and carbon reduction tank through a supernatant return pipe.

[0022] Furthermore, the efficient denitrification and carbon reduction sludge system is obtained by using activated sludge with nitrifying bacteria as the original sludge under stable and continuous aeration conditions. The specific acclimation steps are:

[0023] S1. Take the activated sludge containing nitrifying bacteria from the biochemical system of the sewage treatment plant as the original sludge and inoculate it into the reaction device;

[0024] S2. After homogenization in the regulating tank, the wastewater to be treated is added with alkali and phosphorus source so that the ratio of alkalinity to ammonia nitrogen concentration in the obtained influent is between 9 and 11:1 and the carbon-phosphorus ratio is between 100 and 200:1. After entering the reaction device, it is fully mixed with the original sludge to start the entire acclimation process;

[0025] At the beginning of the entire acclimation process, 10-30% elastic filler is added to the system, the pH value of the influent in the system is maintained at 7.5-8.5, the temperature is 30-34°C, the sludge concentration is 4500-8000 mg / L, the residence time is 80-100h, and the dissolved oxygen concentration in the system is controlled at 2.5-3.5 mg / L. During the gradient down-regulation process, the difference in dissolved oxygen in a single gradient down-regulation is controlled to be less than 1 mg / L. When the minimum dissolved oxygen concentration in the system after down-regulation is ≥2.0 mg / L, the system is operated within the corresponding down-regulated dissolved oxygen concentration range for 10-1 5d; when the minimum dissolved oxygen concentration in the system after the downward adjustment is less than 2.0mg / L, operate within the corresponding dissolved oxygen concentration range after the downward adjustment for 15-30d, and the final dissolved oxygen concentration in the control system is 0.4-1.5mg / L, at this time the dissolved oxygen downward adjustment process is completed; after the dissolved oxygen downward adjustment process is completed, continue to operate within the range of 0.4-1.5mg / L, when the total nitrogen removal rate of the reaction effluent reaches more than 70%, and the COD removal rate reaches more than 85%, and the short-range nitrification and denitrification are mainly in the reaction system, the acclimation process is completed to obtain the said high-efficiency denitrification and carbon reduction sludge system.

[0026] A wastewater energy-saving and efficient denitrification and carbon reduction treatment process, wherein nitrogen-containing wastewater is sent to the above-mentioned denitrification and carbon reduction tank for denitrification and carbon reduction treatment.

[0027] A wastewater energy-saving and efficient carbon reduction and denitrification treatment process, wherein the wastewater is sent to the above-mentioned denitrification and carbon reduction tank for treatment, specifically comprising the following steps:

[0028] 1) Take the high-efficiency denitrification and carbon reduction sludge system and inoculate it into the denitrification and carbon reduction tank;

[0029] The coking wastewater is taken into the regulating tank for water homogenization, and then the treated wastewater is sent to the denitrification and carbon reduction tank, where short-cut nitrification and denitrification reactions and carbon reduction reactions are carried out simultaneously to remove total nitrogen and COD in the wastewater.

[0030] 2) When continuous water inflow is adopted, the effluent from the denitrification and carbon reduction tank enters the first sedimentation tank for mud-water separation, and part of the precipitated sludge is returned to the denitrification and carbon reduction tank, and the remaining sludge is directly discharged; the supernatant after precipitation in the first sedimentation tank enters the short-cut denitrification tank for further short-cut denitrification reaction, further removing the remaining total nitrogen in the effluent from the first sedimentation tank;

[0031] All the wastewater flowing out of the short-cut denitrification tank enters the second sedimentation tank for mud-water separation. Part of the precipitated sludge is returned to the short-cut denitrification tank, and the remaining sludge is directly discharged;

[0032] Part of the supernatant flowing out of the second sedimentation tank is returned to the denitrification and carbon reduction tank to degrade the remaining carbon source, and the remaining supernatant meets the discharge standards;

[0033] When intermittent water inflow is used, the effluent from the denitrification and carbon reduction tank enters the short-cut denitrification tank for short-cut denitrification, and the effluent from the short-cut denitrification tank enters the secondary sedimentation tank for mud-water separation;

[0034] Part of the sludge settled in the secondary sedimentation tank is returned to the short-cut denitrification tank, and the remaining sludge is directly discharged;

[0035] After the total nitrogen concentration in the supernatant obtained from the secondary sedimentation tank reaches the discharge standard, it is directly discharged;

[0036] Otherwise, the obtained supernatant is returned to the denitrification and carbon reduction tank at 0.2 to 0.5 times the total effluent volume of the secondary sedimentation tank for further reaction, and the remaining supernatant is discharged as effluent.

[0037] Furthermore, in step 1), the dissolved oxygen concentration of the reaction system in the denitrification and carbon reduction tank is 0.4-1.5 mg / L, the pH value is 7.5-8.5, the temperature is 30-34°C, the sludge concentration is 4500-8000 mg / L, the residence time is 80-100h, and the daily sludge discharge is calculated based on a sludge age of 30-35d.

[0038] Furthermore, in step 1), the COD concentration in the effluent of the regulating tank is controlled to be ≤6300 mg / L, the ammonia nitrogen concentration is ≤200 mg / L, the total nitrogen concentration is ≤470 mg / L, and the thiocyanate concentration is ≤1100 mg / L.

[0039] Furthermore, in step 1), alkali and phosphorus source are added to the denitrification and carbon reduction pool to control the ratio of alkalinity to ammonia nitrogen concentration in the effluent of the regulating pool to be between 9 and 11:1, and the carbon-phosphorus ratio to be between 100 and 200:1.

[0040] Furthermore, in step 1), the particle size of the elastic filler is 2 to 4 cm, and the filling degree is 10 to 30%.

[0041] Furthermore, when continuous water inflow is adopted, the sludge return ratio of the sludge precipitated from the first sedimentation tank to the denitrification and carbon reduction tank is 0.8 to 1.0;

[0042] A carbon source must also be added to the short-cut denitrification tank, and the ratio of the carbon source concentration added to the short-cut denitrification tank to the total nitrogen concentration in the effluent from the first sedimentation tank must be controlled at 2 to 6:1.

[0043] The sludge return ratio of the sludge precipitated from the second sedimentation tank to the short-cut denitrification tank is 0.5-0.8;

[0044] The volume flow rate of the supernatant Q1 returned to the denitrification and carbon reduction tank is 0 to 0.5 times the total volume flow rate of the effluent from the second sedimentation tank;

[0045] When intermittent water inflow is used, the effluent from the denitrification and carbon reduction pool enters the short-cut denitrification pool and is added with a carbon source. The ratio of the carbon source concentration added to the short-cut denitrification pool to the total nitrogen concentration in the effluent from the denitrification and carbon reduction pool is controlled to be 2 to 6:1, and a short-cut denitrification reaction is carried out to further remove the remaining nitrite nitrogen and a small amount of nitrate nitrogen in the total nitrogen in the effluent from the denitrification and carbon reduction pool.

[0046] Part of the sludge settled in the secondary sedimentation tank is returned to the short-range denitrification tank with a return ratio of 0.5 to 0.8, and the remaining sludge is directly discharged;

[0047] The volume flow rate of the supernatant Q3 returned to the denitrification and carbon reduction tank is 0 to 0.5 times the total volume flow rate of the effluent from the secondary sedimentation tank.

[0048] The beneficial effects of the wastewater energy-saving and high-efficiency denitrification and carbon reduction treatment system and process of the present invention are:

[0049] The wastewater energy-saving and efficient denitrification and carbon reduction treatment system of the present invention can achieve efficient biological denitrification and carbon reduction for coking wastewater in a denitrification and carbon reduction tank, integrating the traditional A / O denitrification function into a process unit (integrated in the same denitrification and carbon reduction tank), effectively shortening the process flow, and the denitrification effect is not limited by factors such as the reflux ratio. The denitrification effect is more efficient and can theoretically be applied to the removal of total nitrogen in any wastewater.

[0050] The energy-saving and efficient wastewater denitrification and carbon reduction treatment system and process of the present invention has a higher denitrification efficiency than existing denitrification processes. The denitrification process removes more than 90% of the total nitrogen in the coking wastewater. Short-cut nitrification and short-cut denitrification are simultaneously carried out in the denitrification and carbon reduction tank, which can replace the traditional A / O denitrification process, solving the bottleneck problem of the denitrification efficiency being limited by the reflux ratio in the traditional A / O process, shortening the denitrification process and reducing the floor space.

[0051] The wastewater energy-saving and efficient denitrification and carbon reduction treatment system of the present invention is a continuous flow process with stable operating conditions and continuous aeration during the reaction process, simple and convenient operation, and low investment cost;

[0052] The nitrification reaction in the wastewater energy-saving and efficient denitrification and carbon reduction treatment process of the present invention is mainly short-cut nitrification. The nitrite nitrogen in the effluent of the denitrification and carbon reduction tank is further removed in the short-cut denitrification tank. The nitrite nitrogen consumes less carbon source in the denitrification process than the traditional nitrification (i.e., nitrate nitrogen denitrification) process. According to theory, 40% of the carbon source can be saved. Therefore, the use of the wastewater energy-saving and efficient denitrification and carbon reduction treatment system of the present invention can significantly reduce the operating cost of the denitrification process.

[0053] The wastewater energy-saving and high-efficiency denitrification and carbon reduction treatment system of the present invention has a high-efficiency denitrification and carbon reduction sludge system, which can simultaneously couple short-range nitrifying bacteria and denitrifying bacteria in a single reactor to achieve high-efficiency biological denitrification and carbon reduction of coking wastewater. Compared with the activated sludge of the traditional A / O process, it has faster reaction efficiency. At the same time, the denitrification effect is not limited by the reflux ratio, which solves the bottleneck problem of further improving the denitrification effect, effectively shortens the process flow, and the denitrification rate can reach more than 70%, with a more efficient denitrification effect.

[0054] The dissolved oxygen concentration adapted to the high-efficiency denitrification and carbon reduction sludge system of the present invention is 0.4-1.5 mg / L. Since microorganisms carry out carbon reduction and denitrification reactions during the water inlet process, oxygen needs to be continuously consumed to achieve the degradation of organic pollutants. Therefore, during the water inlet process, the dissolved oxygen concentration in the system is less than 1.0 mg / L; and during the 4-5 hours of reaction time after the completion of the water inlet, as the degradable pollutants in the system decrease, the dissolved oxygen will increase slightly, and the general dissolved oxygen concentration is less than 1.5 mg / L; therefore, the present invention only needs to control the dissolved oxygen concentration in the reaction system within the range of 0.4-1.5 mg / L, thereby effectively reducing the aeration volume in the denitrification and carbon reduction tank; and since the high-efficiency denitrification and carbon reduction sludge system of the present invention carries out a short-cut nitrification and denitrification reaction, the short-cut nitrification reaction can significantly save oxygen demand compared to the complete nitrification reaction, so the aeration volume can also be reduced, thereby saving aeration treatment costs, thereby reducing operating costs;

[0055] Since 7.14 g of alkalinity is consumed for each 1 g of ammonia nitrogen in the short-cut nitrification reaction (equivalent to 7.14 g of sodium bicarbonate), and 3.57 g of alkalinity is generated for each 1 g of nitrate nitrogen in the short-cut denitrification reaction (equivalent to 3.57 g of sodium bicarbonate), and the conventional A / O denitrification process cannot simultaneously carry out the short-cut nitrification reaction and the short-cut denitrification reaction in the same reactor, the use of the high-efficiency denitrification and carbon reduction sludge system of the present invention for denitrification treatment can reduce the consumption of alkalinity, thereby reducing the amount of alkalinity added, achieving the purpose of energy saving and reducing operating costs;

[0056] The high-efficiency denitrification and carbon reduction sludge system of the present invention is used to denitrify coking wastewater. During the entire operation cycle in the denitrification and carbon reduction tank, there is no need to precisely control the amount of dissolved oxygen. The aeration mode is operated in a non-discriminatory manner throughout the entire process, making the denitrification treatment operation of the coking wastewater simpler and more convenient.

[0057] During the acclimation process of the high-efficiency denitrification and carbon reduction sludge system of the present invention, the different tolerance levels of AOB bacteria and NOB bacteria in nitrifying bacteria to dissolved oxygen are utilized to control the dissolved oxygen concentration in the system to maintain a relatively low dissolved oxygen environment, thereby inhibiting nitrite oxidizing bacteria (NOB bacteria) in nitrifying bacteria, so that ammonia oxidizing bacteria (AOB bacteria) become the dominant bacterial group, and carry out a short-range nitrification reaction to convert ammonia nitrogen in the system into nitrite nitrogen; denitrifying bacteria are mainly enriched inside the filler in the early stage of acclimation, and the dissolved oxygen environment inside the filler is more suitable for the survival of denitrifying bacteria. As the acclimation process proceeds, the dissolved oxygen in the system reaches a relatively low level. Under the action of stirring and aeration, the microbial species in the mud film system tend to be mixed. At this time, the high-efficiency denitrification and carbon reduction sludge system has a high-efficiency denitrification capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1This is a schematic structural diagram of a wastewater energy-saving and high-efficiency denitrification and carbon reduction treatment system when continuous water inflow is adopted in Example 2 of the present invention;

[0059] Figure 2 It is a structural schematic diagram of a wastewater energy-saving and high-efficiency denitrification and carbon reduction treatment system when intermittent water inflow is adopted in Example 3 of the present invention. DETAILED DESCRIPTION

[0060] The technical solutions in the embodiments of the present invention are described clearly and completely below. Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0061] A wastewater energy-saving and efficient denitrification and carbon reduction treatment process comprises the following steps:

[0062] 1) Take the high-efficiency denitrification and carbon reduction sludge system and inoculate it into the denitrification and carbon reduction tank, and add fillers;

[0063] The effluent from the regulating tank enters the denitrification and carbon reduction tank;

[0064] 2) When continuous water inflow is adopted, the effluent from the denitrification and carbon reduction tank enters the first sedimentation tank for mud-water separation. Part of the sludge after sedimentation flows back to the inlet of the denitrification and carbon reduction tank, and the remaining sludge is directly discharged;

[0065] The effluent from the first sedimentation tank all enters the short-cut denitrification tank, and carbon source is added to carry out short-cut denitrification reaction;

[0066] All the effluent from the short-cut denitrification tank enters the second sedimentation tank for mud-water separation. Part of the effluent from the second sedimentation tank is returned to the denitrification and carbon reduction tank, and the rest is discharged as the total effluent meeting the standards;

[0067] Part of the sludge precipitated in the second sedimentation tank is returned to the inlet of the short-range denitrification tank, and the remaining sludge is directly discharged.

[0068] When intermittent water inflow is used, the effluent from the denitrification and carbon reduction tank enters the short-cut denitrification tank, and a carbon source is added to carry out a short-cut denitrification reaction. The effluent from the short-cut denitrification tank enters the secondary sedimentation tank for mud-water separation; part of the sludge precipitated in the secondary sedimentation tank is returned to the inlet of the short-cut denitrification tank, and the remaining sludge is directly discharged; after the total nitrogen concentration in the supernatant obtained in the secondary sedimentation tank reaches the discharge standard, it is directly discharged; otherwise, the supernatant obtained is returned to the denitrification and carbon reduction tank at 0.2 to 0.5 times the total effluent volume of the secondary sedimentation tank for further reaction, and the remaining supernatant is discharged as effluent.

[0069] The process parameters involved in the energy-saving and efficient denitrification and carbon reduction treatment process for wastewater are shown in the table below:

[0070] Table 1 List of denitrification process parameters when continuous water inflow is used

[0071]

[0072] Table 2 List of denitrification process parameters when intermittent water inflow is used

[0073]

[0074]

[0075] Example 1 A method for acclimating a highly efficient denitrification and carbon reduction sludge system

[0076] This embodiment is a method for acclimating a sludge system with high efficiency in denitrification and carbon reduction, which specifically includes the following steps:

[0077] 1) Constructing an SBR reactor. The reactor is a round organic glass cylinder with a total effective volume of 11 L. The water treatment rate is 3 L / d. The water is fed by a peristaltic pump. A single water inlet cycle is 24 h, including 23 h of reaction and 1 h of standing and draining. The reaction process includes 17 h of water inlet, and the total reaction residence time is 80.6 h.

[0078] The activated sludge with nitrifying bacteria from the secondary sedimentation tank of the coking wastewater treatment plant (adapted dissolved oxygen concentration is 2-6 mg / L) was inoculated into the SBR reactor. The inoculated sludge concentration was 4572 mg / L, and 2 cm of polyurethane filler was added, with a filling degree of 15%.

[0079] 2) Take the coking wastewater after homogenization in the regulating tank, add potassium bicarbonate and disodium hydrogen phosphate, so that the ratio of alkalinity to ammonia nitrogen concentration in the obtained influent is between 9 and 11:1 and the carbon-phosphorus ratio is 100 to 200:1. After entering the reaction device, it is fully mixed with the original sludge and filler.

[0080] At the beginning of the acclimation process, the initial influent COD concentration was controlled at 2335 mg / L, the total nitrogen concentration was 186 mg / L, the ammonia nitrogen concentration was 53.90 mg / L, the thiocyanate concentration was 23.30 mg / L, and the pH value was 9.2. The dissolved oxygen concentration in the SBR reactor was controlled by adjusting the aeration rate. The specific dissolved oxygen adjustment range and operation days during the implementation process are shown in Table 3 below:

[0081] Table 3 Dissolved oxygen gradient adjustment process table

[0082] Dissolved oxygen range (mg / L) Operating days (d) 2.5～3.5 10 1.5～2.5 15 1.0～1.5 15 0.4～1.5 15

[0083] Control the temperature in the SBR reactor to 30-34°C, the sludge concentration to 4500-6000 mg / L, the pH to 8.0-8.5, and the sludge age to 30-35 days. The operating conditions will fluctuate slightly with changes in the influent water quality, so they only need to be controlled within the above ranges.

[0084] S3, after the dissolved oxygen reduction process is completed, it continues to operate within the range of 0.4-1.5 mg / L for 5 days. The total nitrogen in the effluent of the system is NO2 - As the main component, the domesticated bacteria can simultaneously carry out short-term nitrification and denitrification under this dissolved oxygen concentration, and the total nitrogen removal rate reaches more than 70%, completing the domestication process. The entire domestication period is generally 2 to 3 months, and the domestication period of this embodiment is 2 months.

[0085] In addition, during the acclimation process, the dissolved oxygen concentration in the system is adjusted and the load is increased at the same time. The single increase gradient in this embodiment is based on Table 4. The load increase process takes the total nitrogen load in the wastewater to be treated as the end point of the increase. The total nitrogen load increase process in Table 4 of this embodiment is only for illustrating the effect of the present invention and is not intended to limit the scope of protection of the claims of the present invention.

[0086] The acclimation process and results using the above acclimation method are shown in the table below.

[0087] Table 4 Summary of acclimation process and results

[0088]

[0089] It can be seen from the test results in Table 4 that as the acclimation process proceeds, the total nitrogen removal rate of the effluent after the reaction shows a gradual upward trend, and the final high-efficiency denitrification and carbon reduction sludge system can stably achieve a total nitrogen removal rate of more than 70%, proving that the high-efficiency denitrification and carbon reduction sludge system of the present invention has more efficient denitrification performance than the traditional AO process, and also has a good removal effect on COD, thiocyanate and ammonia nitrogen in wastewater.

[0090] On this basis, the concentration of total nitrogen in the influent was increased, and the final treatment concentration of total nitrogen was increased to 476 mg / L. When the total nitrogen in the influent was greater than 353 mg / L, the process parameters of the reaction system were adjusted. The process parameter adjustments are shown in Table 5:

[0091] Table 5 Process parameter adjustment table

[0092] Sludge concentration Dwell time Filler particle size Filling Water inlet time pH in the system 6000～8000 85～100 3.5 30 18 7.5～8.5

[0093] The specific effects are shown in the table below:

[0094] Table 6 Acclimation process and results

[0095]

[0096] It can be seen from the operating results in Table 6 that with the increase of high load, the total nitrogen removal rate of the effluent after the reaction can still be stabilized at more than 70%, and the COD removal rate reaches more than 85%, indicating that the high-efficiency denitrification and carbon reduction sludge system has higher shock resistance.

[0097] Example 2 A wastewater energy-saving and efficient denitrification and carbon reduction treatment system and process

[0098] This embodiment is a wastewater energy-saving and efficient denitrification and carbon reduction treatment system and process, specifically:

[0099] 1. A wastewater energy-saving and efficient denitrification and carbon reduction treatment system

[0100] When continuous water inflow is adopted in this embodiment, Figure 1 As shown, a wastewater energy-saving and efficient denitrification and carbon reduction treatment system includes a regulating tank, a denitrification and carbon reduction tank with fillers and a high-efficiency denitrification and carbon reduction sludge system, a first sedimentation tank, a short-cut denitrification tank, and a second sedimentation tank connected in series.

[0101] The outlet of the first sedimentation tank is connected to the inlet of the denitrification and carbon reduction tank through the first sludge return pipe; the outlet of the second sedimentation tank is connected to the inlet of the short-cut denitrification tank through the second sludge return pipe; the outlet of the second sedimentation tank is connected to the inlet of the denitrification and carbon reduction tank through the supernatant return pipe;

[0102] Both the sludge return pipe and the supernatant return pipe are equipped with flow control devices (usually flow valves).

[0103] The denitrification and carbon reduction tank in this embodiment is provided with a dissolved oxygen control system, and its internal structure is the same as that of a traditional aerobic tank.

[0104] 2. A wastewater energy-saving and efficient denitrification and carbon reduction treatment process

[0105] This embodiment uses the above-mentioned wastewater energy-saving and high-efficiency denitrification and carbon reduction treatment system to treat coking wastewater (this embodiment uses ammonia distillation wastewater in the coking wastewater as the wastewater to be treated). The specific method is as follows:

[0106] 1) The coking wastewater is first homogenized and weighed in the regulating tank. The concentration ranges of the pollutants in the effluent of the regulating tank in this embodiment are shown in the following table:

[0107] Table 7 List of pollutant concentration ranges in regulated effluent

[0108] Pollutant indicators Ammonia nitrogen COD Thiocyanate Total nitrogen pH Concentration (mg / L) 50～155 2133～6052 388～1071 166～462 7.2～9.6

[0109] The sludge from the high-efficiency denitrification and carbon reduction sludge system was inoculated into the above-mentioned denitrification and carbon reduction tank at a sludge concentration of 5011 mg / L and polyurethane filler with a particle size of 2 cm was added, with a filling degree of 20%;

[0110] The effluent from the regulating tank enters the denitrification and carbon reduction tank, into which sodium bicarbonate and disodium hydrogen phosphate are added to control the ratio of alkalinity to ammonia nitrogen concentration in the influent between 9.4 and 10.2:1 and the carbon-phosphorus ratio between 106.7 and 188.4:1. The dissolved oxygen concentration is also controlled at 0.4 to 1.5 mg / L, the pH value is 7.5 to 8.5, the temperature is 30 to 34°C, the residence time is 80 to 98 hours, the sludge concentration is 4563 to 7815 mg / L, and the daily sludge discharge is calculated based on a sludge age of 30 to 35 days. In the denitrification and carbon reduction tank, high-efficiency denitrification and carbon reduction sludge is first used to decarbonize the COD in the influent and simultaneously convert thiocyanate into ammonia nitrogen, achieving thiocyanate degradation. The composite denitrifying bacteria in the high-efficiency denitrification and carbon reduction sludge system then simultaneously carry out short-term nitrification and denitrification reactions on the ammonia nitrogen in the system under stable aeration conditions, achieving a total nitrogen removal rate of over 70%.

[0111] 2) The effluent from the denitrification and carbon reduction tank enters the first sedimentation tank for mud-water separation. Part of the sludge after sedimentation is returned to the inlet of the denitrification and carbon reduction tank through the first sludge return pipe using a reflux pump. The sludge return ratio is 0.8-1.0;

[0112] The remaining sludge is discharged directly through the submersible sewage pump;

[0113] All the effluent from the first sedimentation tank enters the short-cut denitrification tank, and carbon source is added through a dosing metering pump. The ratio of the carbon source concentration added to the short-cut denitrification tank to the total nitrogen concentration in the effluent from the denitrification and carbon reduction tank is controlled to be 3-6:1, and a short-cut denitrification reaction is carried out to further remove the remaining nitrite nitrogen and a small amount of nitrate nitrogen in the total nitrogen in the effluent from the first sedimentation tank. The short-cut denitrification tank is equipped with a stirring device but no aeration device. During operation, the dissolved oxygen carried by the effluent from the denitrification and carbon reduction tank maintains the dissolved oxygen concentration in the system below 0.5 mg / L. Continuous water inlet and outlet is used, and the residence time is 3 hours.

[0114] The effluent from the short-cut denitrification tank all enters the secondary sedimentation tank for mud-water separation;

[0115] The effluent from the second sedimentation tank is divided into supernatant Q1 and supernatant Q2, and the supernatant Q1 is 0.2 to 0.4 times the total volume of the supernatant;

[0116] The supernatant Q1 is refluxed to the inlet of the denitrification and carbon reduction pool through the supernatant reflux pipe by a reflux pump. The remaining carbon source in the supernatant Q1 is further utilized and degraded in the denitrification and carbon reduction pool, and the supernatant Q2 is discharged as the total effluent meeting the standards;

[0117] Part of the sludge precipitated in the second sedimentation tank is returned to the inlet of the short-range denitrification tank through the second sludge return pipe by a return pump. The sludge return ratio is 0.5, and the remaining sludge is directly discharged.

[0118] The comparison results of the treatment effect of coking wastewater using the wastewater energy-saving and high-efficiency denitrification and carbon reduction treatment process of Example 2 and the treatment effect using the traditional A / O tank are shown in the following table:

[0119] Table 8 Comparison of the results of multi-day operation tests of the denitrification method of the present invention and conventional A / O tank treatment

[0120]

[0121] The comparison results in Table 8 are the fluctuation range of the denitrification effect during a period of operation. Among them, the specific results of the wastewater energy-saving and high-efficiency denitrification and carbon reduction treatment process for coking wastewater after a period of stable operation are shown in Table 9:

[0122] Table 9 List of denitrification results of denitrification and carbon reduction pool

[0123]

[0124] Table 10 Summary of denitrification results in short-cut denitrification tank

[0125]

[0126] It can be seen from the results in Tables 9 and 10 that, by adopting the wastewater energy-saving and efficient denitrification and carbon reduction treatment process of the present invention, the effluent of the coking wastewater after homogenization in the regulating tank is treated in the denitrification and carbon reduction tank and the short-cut denitrification tank, and the final effluent has an average ammonia nitrogen concentration of 2.36 mg / L, an average COD concentration of 208 mg / L, and an average total nitrogen concentration of 36 mg / L. The total nitrogen removal rate of the final effluent reaches an average of 90.31%, and the COD removal rate reaches an average of 95.56%. Therefore, compared with the traditional AO process, the wastewater energy-saving and efficient denitrification and carbon reduction treatment system of the present invention has higher denitrification efficiency and carbon reduction effect, and the effluent ammonia nitrogen and thiocyanate can also meet the emission requirements.

[0127] Example 3 A wastewater energy-saving and efficient denitrification and carbon reduction treatment system and process

[0128] Example 3 is a wastewater energy-saving and efficient denitrification and carbon reduction treatment system and process, specifically:

[0129] 1. A wastewater energy-saving and efficient denitrification and carbon reduction treatment system

[0130] In this implementation, intermittent water inflow is adopted, such as Figure 2As shown, a wastewater energy-saving and efficient denitrification and carbon reduction treatment system includes a regulating tank, a denitrification and carbon reduction tank with fillers and a high-efficiency denitrification and carbon reduction sludge system, a short-cut denitrification tank and a secondary sedimentation tank connected in series in sequence; the outlet of the secondary sedimentation tank is connected to the inlet of the short-cut denitrification tank through a sludge return pipe; the outlet of the secondary sedimentation tank is connected to the inlet of the denitrification and carbon reduction tank through a supernatant return pipe; the sludge return pipe and the supernatant return pipe are both provided with flow control devices (generally flow valves).

[0131] The denitrification and carbon reduction tank in this embodiment is equipped with a dissolved oxygen control system, the internal structure of which is the same as that of a traditional SBR reactor. The dissolved oxygen control system includes an aeration fan, an aeration plate, a gas regulating valve and an online dissolved oxygen monitor.

[0132] 2. A wastewater energy-saving and efficient denitrification and carbon reduction treatment process, specifically comprising the following steps:

[0133] 1) The coking wastewater is first homogenized and weighed in the regulating tank. The concentrations of various pollutants in the effluent of the regulating tank in this embodiment are shown in the following table:

[0134] Table 11 List of concentration ranges of pollutants in regulated effluent

[0135] Pollutant indicators Ammonia nitrogen COD Thiocyanate Total nitrogen pH Concentration (mg / L) 50.4～155.2 2342～6288 412.8～1076.5 215～467 7.5～9.8

[0136] The sludge in the high-efficiency denitrification and carbon reduction sludge system was inoculated into the above-mentioned denitrification and carbon reduction tank at 5018 mg / L and polyurethane filler with a particle size of 2.5 cm was added, with a filling degree of 15%. The operation process in the denitrification and carbon reduction tank included 23 hours of reaction and 1 hour of standing and drainage, of which the reaction process included 18 hours of water intake.

[0137] The effluent from the regulating tank enters the denitrification and carbon reduction tank, and alkali and phosphorus sources are added to the denitrification and carbon reduction tank. In this embodiment, the ratio of alkalinity to ammonia nitrogen concentration in the influent is controlled between 9.2 and 11:1, and the carbon-phosphorus ratio is 150 to 189:1. At the same time, the dissolved oxygen concentration is controlled to be 0.4 to 1.5 mg / L, the pH value is 7.5 to 8.5, the temperature is 30 to 34°C, the sludge concentration is 4722 to 7806 mg / L, and the daily sludge discharge is calculated based on a sludge age of 30 to 35 days. The denitrification bacteria in the high-efficiency denitrification and carbon reduction sludge system simultaneously carry out short-term nitrification and denitrification reactions on the ammonia nitrogen in the system under stable aeration conditions to remove the total nitrogen in the effluent from the regulating tank.

[0138] 2) The effluent from the denitrification and carbon reduction pool enters the short-cut denitrification pool and is fed with a carbon source through a dosing metering pump. The ratio of the carbon source concentration fed into the short-cut denitrification pool to the total nitrogen concentration in the effluent from the denitrification and carbon reduction pool is between 3 and 6:1, and a short-cut denitrification reaction is carried out to further remove the remaining nitrite nitrogen and a small amount of nitrate nitrogen in the total nitrogen in the effluent from the denitrification and carbon reduction pool. The short-cut denitrification pool is equipped with a stirring device but no aeration device. During operation, the dissolved oxygen carried in the effluent from the denitrification and carbon reduction pool is used to maintain the dissolved oxygen concentration in the system at ≤0.5 mg / L, and the operation is carried out in a continuous water inlet and outlet manner with a residence time of 3 hours.

[0139] The effluent from the short-cut denitrification tank all enters the secondary sedimentation tank for mud-water separation;

[0140] After the total nitrogen concentration in the effluent from the secondary sedimentation tank reaches the discharge standard, it will be discharged directly;

[0141] Otherwise, 0.2 to 0.5 times the total effluent volume of the secondary sedimentation tank is returned to the denitrification and carbon reduction tank through the supernatant reflux pipeline for further reaction and degradation of the remaining carbon source, and the remaining supernatant is discharged as effluent;

[0142] Part of the sludge settled in the secondary sedimentation tank is returned to the short-range denitrification tank through the sludge return pipe using a return pump, with a return ratio of 0.5, and the remaining sludge is directly discharged through a submersible sewage pump.

[0143] The energy-saving and efficient denitrification and carbon reduction treatment process for wastewater of Example 3 of the present invention was used to treat coking wastewater. The specific results of the effluent after stable operation are shown in Tables 12 and 13:

[0144] Table 12 Treatment results of denitrification and carbon reduction pool

[0145]

[0146] Table 13 Treatment results of short-cut denitrification pool

[0147]

[0148] It can be seen from the results in Table 12 and Table 13 that after the regulating tank wastewater is treated in the denitrification and carbon reduction tank and the short-cut denitrification tank, the average ammonia nitrogen concentration of the final effluent is 5.01 mg / L, the average COD concentration is 327 mg / L, and the average total nitrogen concentration is 38 mg / L. The total nitrogen removal rate of the final effluent reaches an average of 90.41%, and the COD removal rate reaches an average of 94.12%. Therefore, compared with the traditional AO process, the wastewater energy-saving and efficient denitrification and carbon reduction treatment system of the present invention has a more efficient denitrification and carbon reduction effect, which not only simplifies the process flow, but also reduces investment costs and operating expenses.

[0149] Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

Claims

1. A wastewater energy-saving and efficient denitrification and carbon reduction treatment system, characterized in that: Including denitrification and carbon reduction pools; The dissolved oxygen concentration in the denitrification and carbon reduction tank is 0.4~1.5mg / L; The denitrification and carbon reduction pool is equipped with fillers and a high-efficiency denitrification and carbon reduction sludge system, which can simultaneously carry out short-term nitrification, denitrification and carbon reduction reactions under stable and continuous aeration conditions; When continuous water inflow is adopted, the wastewater energy-saving and high-efficiency denitrification and carbon reduction treatment system further comprises a regulating tank, a first sedimentation tank, a short-cut denitrification tank and a second sedimentation tank connected in series in sequence; The denitrification and carbon reduction tank is set between the regulating tank and the first sedimentation tank; The first sedimentation tank and the denitrification and carbon reduction tank, as well as the second sedimentation tank and the short-cut denitrification tank are connected via sludge return pipes. The second sedimentation tank is connected to the denitrification and carbon reduction tank through a supernatant return pipe; When intermittent water inflow is adopted, the wastewater energy-saving and high-efficiency denitrification and carbon reduction treatment system further comprises a regulating tank, a short-cut denitrification tank and a secondary sedimentation tank connected in series in sequence; The denitrification and carbon reduction tank is set between the regulating tank and the short-cut denitrification tank; The secondary sedimentation tank is connected to the short-cut denitrification tank through a sludge return pipe; The secondary sedimentation tank is connected to the denitrification and carbon reduction tank through a supernatant return pipe.

2. The wastewater energy-saving and high-efficiency denitrification and carbon reduction treatment system according to claim 1 is characterized in that: The efficient denitrification and carbon reduction sludge system is obtained under stable and continuous aeration conditions, and the specific acclimation steps are as follows: At the beginning of the entire acclimation process, 10~30% elastic filler was added to the system, the pH value of the influent in the system was maintained at 7.5~8.5, the temperature was 30~34℃, the sludge concentration was 4500~8000mg / L, the residence time was 80~100h, and the dissolved oxygen concentration in the system was controlled at 2.5~3.5mg / L. During the gradient down-regulation process, the difference in dissolved oxygen in a single gradient down-regulation was controlled to be less than 1mg / L. When the minimum dissolved oxygen concentration in the system after down-regulation was ≥2.0mg / L, the system was operated within the corresponding down-regulated dissolved oxygen concentration range for 10~1 5d; when the minimum dissolved oxygen concentration in the system after the downward adjustment is less than 2.0mg / L, operate within the corresponding dissolved oxygen concentration range after the downward adjustment for 15-30d, and the final dissolved oxygen concentration in the control system is 0.4-1.5mg / L, at this time the dissolved oxygen downward adjustment process is completed; after the dissolved oxygen downward adjustment process is completed, continue to operate within the range of 0.4-1.5mg / L, when the total nitrogen removal rate of the reaction effluent reaches more than 70%, and the COD removal rate reaches more than 85%, and the short-range nitrification and denitrification are mainly in the reaction system, the acclimation process is completed to obtain the said high-efficiency denitrification and carbon reduction sludge system.

3. A wastewater energy-saving and efficient denitrification and carbon reduction treatment process, characterized in that: The nitrogen-containing wastewater is sent to the denitrification and carbon reduction pool as described in claim 1 or 2 for denitrification and carbon reduction treatment.

4. A wastewater energy-saving and efficient carbon reduction and denitrification treatment process, characterized in that: The wastewater is sent to the denitrification and carbon reduction pool as claimed in claim 1 or 2 for treatment, which specifically includes the following steps: 1) Take the high-efficiency denitrification and carbon reduction sludge system and inoculate it into the denitrification and carbon reduction tank; The coking wastewater is taken into the regulating tank for water homogenization, and then the treated wastewater is sent to the denitrification and carbon reduction tank, where short-cut nitrification and denitrification reactions and carbon reduction reactions are carried out simultaneously to remove total nitrogen and COD in the wastewater. 2) When continuous water inflow is used, the effluent from the denitrification and carbon reduction tank enters the first sedimentation tank for sludge-water separation. Part of the precipitated sludge is returned to the denitrification and carbon reduction tank, and the remaining sludge is directly discharged. The supernatant after precipitation in the first sedimentation tank enters the short-cut denitrification tank for further short-cut denitrification reaction to further remove the remaining total nitrogen in the effluent from the first sedimentation tank. All the wastewater flowing out of the short-cut denitrification tank enters the second sedimentation tank for mud-water separation. Part of the precipitated sludge is returned to the short-cut denitrification tank, and the remaining sludge is directly discharged; Part of the supernatant Q1 flowing out of the second sedimentation tank is returned to the denitrification and carbon reduction tank to degrade the remaining carbon source, and the remaining supernatant Q2 meets the discharge standards; When intermittent water inflow is used, the effluent from the denitrification and carbon reduction tank enters the short-cut denitrification tank for short-cut denitrification, and the effluent from the short-cut denitrification tank enters the secondary sedimentation tank for mud-water separation; Part of the sludge settled in the secondary sedimentation tank is returned to the short-cut denitrification tank, and the remaining sludge is directly discharged; After the total nitrogen concentration in the supernatant obtained from the secondary sedimentation tank reaches the discharge standard, it is directly discharged; Otherwise, the obtained supernatant Q3 is returned to the denitrification and carbon reduction tank at 0.2~0.5 times the total effluent volume of the secondary sedimentation tank for further reaction, and the remaining supernatant is discharged as effluent.

5. The wastewater energy-saving and high-efficiency carbon reduction and denitrification treatment process according to claim 4 is characterized in that: In step 1), the dissolved oxygen concentration of the reaction system in the denitrification and carbon reduction tank is 0.4~1.5 mg / L, the pH value is 7.5~8.5, the temperature is 30~34°C, the sludge concentration is 4500~8000 mg / L, the residence time is 80~100h, and the daily sludge discharge is calculated based on a sludge age of 30~35d.

6. The wastewater energy-saving and high-efficiency carbon reduction and denitrification treatment process according to claim 4 or 5, characterized in that: In step 1), the COD concentration in the effluent of the regulating tank is controlled to be ≤6300 mg / L, the ammonia nitrogen concentration is ≤200 mg / L, the total nitrogen concentration is ≤470 mg / L, and the thiocyanate concentration is ≤1100 mg / L.

7. The wastewater energy-saving and high-efficiency carbon reduction and denitrification treatment process according to claim 4 or 5, characterized in that: In step 1), alkali and phosphorus sources are added to the denitrification and carbon reduction pool to control the ratio of alkalinity to ammonia nitrogen concentration in the effluent of the regulating pool to be between 9 and 11:1, and the carbon-phosphorus ratio to be between 100 and 200:

1.

8. The wastewater energy-saving and high-efficiency carbon reduction and denitrification treatment process according to claim 4 or 5, characterized in that: In step 1), the particle size of the elastic filler is 2-4 cm and the filling degree is 10-30%.

9. The wastewater energy-saving and high-efficiency carbon reduction and denitrification treatment process according to claim 4 or 5, characterized in that: When continuous water inflow is used, the sludge return ratio from the first sedimentation tank to the denitrification and carbon reduction tank is 0.8~1.0; A carbon source must also be added to the short-cut denitrification tank, and the ratio of the carbon source concentration added to the short-cut denitrification tank to the total nitrogen concentration in the effluent of the first sedimentation tank should be controlled at 2-6:

1. The sludge return ratio from the second sedimentation tank to the short-cut denitrification tank is 0.5~0.8; The volume flow rate of the supernatant Q1 returned to the denitrification and carbon reduction tank is 0 to 0.5 times the total volume flow rate of the effluent from the second sedimentation tank; When intermittent water inflow is used, the effluent from the denitrification and carbon reduction pool enters the short-cut denitrification pool and is added with a carbon source. The ratio of the carbon source concentration added to the short-cut denitrification pool to the total nitrogen concentration in the effluent from the denitrification and carbon reduction pool is controlled to be 2-6:1, and a short-cut denitrification reaction is carried out to further remove the remaining nitrite nitrogen and a small amount of nitrate nitrogen in the total nitrogen in the effluent from the denitrification and carbon reduction pool. Part of the sludge settled in the secondary sedimentation tank is returned to the short-range denitrification tank with a return ratio of 0.5~0.8, and the remaining sludge is directly discharged.

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