CN111056708A - Two-stage denitrification wastewater denitrification treatment process - Google Patents
Two-stage denitrification wastewater denitrification treatment process Download PDFInfo
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/28—Anaerobic digestion processes
- C02F3/286—Anaerobic digestion processes including two or more steps
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F2001/007—Processes including a sedimentation step
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/16—Nitrogen compounds, e.g. ammonia
Abstract
The invention discloses a two-stage denitrification wastewater denitrification treatment process. The process comprises the following steps: a pre-denitrification process, an aerobic nitrification process, a post-denitrification process and a sludge backflow process. The invention compares the advantages and the disadvantages of the pre-denitrification process and the post-denitrification process by analysis, combines the pre-denitrification process and the post-denitrification process, and adds PBS, PHB and old rice in the post-denitrification process, thereby overcoming the defect of insufficient carbon source in the two-stage denitrification stage, strengthening the post-denitrification capability, further removing nitrogen elements in the wastewater, and the PBS still has good performance after the reactor operates for 230 days. The sludge in the sedimentation tank flows back to the first section of the denitrification tank through the backflow system, the backflow of the sludge enables microorganisms to be attached to and grow on the filler to form the sludge-film composite bioreactor, and the denitrification treatment capacity of the process is enhanced. The equipment can realize unattended operation, has small occupied area and is convenient to move or reuse in a moving way.
Description
Technical Field
The invention relates to the field of sewage treatment, in particular to a wastewater denitrification treatment process with two-stage denitrification.
Background
The water eutrophication is water pollution caused by excessive content of N, P and other nutritive salts in the water, and the essence is that the species distribution of the water ecological system is unbalanced due to unbalanced input and output of the nutritive salts, so that a single species grows excessively, the flow of the substances and energy of the system is damaged, and the whole water ecological system gradually goes to death. Therefore, the removal of nitrogen has become an important factor in the treatment of wastewater.
The traditional biological denitrification process mainly comprises two ways, namely assimilation of microorganisms, synthesis of microbial cells by using nitrogen in a water body as a cytoplasmic component, discharge of the nitrogen out of a sewage treatment system in the form of excess sludge along with aged microorganisms, and removal of the nitrogen by the nitrogen treatment system is small, and only about 3% of nitrogen in original sewage can be removed generally; secondly, on the basis of nitrifying bacteria and denitrifying bacteria, the ammonia nitrogen is oxidized into nitrate nitrogen by the nitrifying bacteria under aerobic conditions, then the nitrate nitrogen and organic matters are subjected to denitrification reaction under anoxic conditions by the denitrifying bacteria to generate nitrogen, and the nitrogen is removed from the sewage. The traditional biological denitrification process can not ensure the standard discharge of the high-nitrogen wastewater. For example, Hao Xiao Di, etc. (Hao Xiao Di, Li Tian Yu, Wu Yu, Markvan Loosdrecht, etc.. A2Suitability discussion of/O process for upgrading and reconstruction of sewage treatment plant [ J]China water supply and drainage, 2017,33(21),18-24), and nitrogen elements in sewage are removed by using a UCT process, the process is slightly improved in denitrification efficiency compared with the traditional biological denitrification process, but the process still has the problems of large equipment floor area, high capital construction operating cost and the like, and effluent containing nitrate nitrogen (more than or equal to 10mg/L) with certain concentration cannot be removed, so that the total nitrogen in the effluent is causedThe concentration is higher.
Disclosure of Invention
In order to solve the problems, the invention discloses a wastewater denitrification treatment process of two-stage denitrification. The process can efficiently remove nitrogen in the wastewater and ensure the wastewater to reach the discharge standard, and the integrated reaction equipment independently developed by applying the technology concentrates denitrification treatment in one reaction equipment, so that the equipment has the advantages of small floor area, low capital construction running cost and good removal effect, and is an effective technical means for solving the problem of wastewater denitrification treatment.
The purpose of the invention is realized by at least one of the following technical solutions.
The invention provides a two-stage denitrification wastewater denitrification treatment process, which comprises the following steps:
(1) pre-denitrification treatment (the dissolved oxygen content DO in the sewage is less than or equal to 0.5 mg/L): arranging a section of denitrification tank at the front end of the aerobic tank, introducing the sewage into the section of denitrification tank, arranging a fiber ball filter material and a stirring device in the section of denitrification tank, starting the stirring device to carry out pre-denitrification treatment, reducing nitrate nitrogen into pollution-free nitrogen by taking nitrate nitrogen in reflux nitrification liquid as an electron acceptor and organic matters in the sewage as an electron donor under the action of facultative anaerobic denitrifying bacteria, and removing a nitrogen source (nitrogen element) in the wastewater to obtain the sewage after the pre-denitrification treatment;
(2) aerobic nitrification treatment (DO is more than or equal to 3 mg/L): introducing the sewage subjected to the pre-denitrification treatment in the step (1) into an aerobic tank, wherein fillers are arranged in the aerobic tank, the types of the fillers comprise biological combined fillers and fiber ball filter materials, uniformly aerating in an aeration tank through an aeration device, carrying out aerobic nitrification treatment, nitrifying ammonia nitrogen in the sewage subjected to the pre-denitrification treatment into nitrate nitrogen by nitrifying bacteria to obtain nitrified liquid and the wastewater treated in the aerobic tank, and refluxing the nitrified liquid to the primary denitrification tank;
(3) post denitrification treatment (DO is less than or equal to 0.5 mg/L): arranging a second-stage denitrification tank at the rear end of the aerobic tank, guiding the wastewater treated by the aerobic tank in the step (2) into the second-stage denitrification tank, arranging a fiber ball filter material and a stirring device in the second-stage denitrification tank, starting the stirring device, carrying out post-denitrification treatment by taking nitrate nitrogen flowing out of the aerobic tank as an electron acceptor under the action of facultative anaerobic denitrifying bacteria, and reducing the nitrate nitrogen into pollution-free nitrogen by taking organic matters remaining in the wastewater as an electron donor to obtain the wastewater after the post-denitrification treatment;
(4) sludge backflow: and (4) introducing the wastewater subjected to the post denitrification treatment in the step (3) into a sedimentation tank, performing sedimentation treatment to obtain sludge and liquid subjected to sedimentation treatment, refluxing the sludge into a first-stage denitrification tank, and discharging the liquid subjected to sedimentation treatment to the outside to finish the denitrification treatment of the wastewater.
Further, in the step (1), the time for the sewage to stay in the first-stage denitrification tank for pre-denitrification treatment is 3.6-6 hours.
Furthermore, the ball diameters of the fiber ball filter materials in the steps (1), (2) and (3) are all 40-80 mm, the specific surface areas of the fiber ball filter materials are 2800 and 3500 square meters/cubic meter, and the total porosity of the fiber ball filter materials is 92-95%. The ultrahigh specific surface area and porosity provide a great space for the attachment growth of microorganisms, the concentration of the microorganisms in the pool is further improved, and the effective removal of pollutants in the wastewater is ensured.
Further, the specific surface area of the biological combined filler in the step (2) is 3300-; the structure of the biological combined filler is that a plastic wafer is changed into a double-ring large plastic ring by pressing and buckling, and the hydroformylation fiber or the polyester yarn is pressed on the ring of the ring, so that the fiber bundles are uniformly distributed. The biological combined filler is purchased from Hengshi environmental protection science and technology limited company in Yixing city, and the model is 150 multiplied by 100 mm. The ultrahigh specific surface area and porosity provide a great space for the attachment growth of microorganisms, the concentration of the microorganisms in the pool is further improved, and the effective removal of pollutants in the wastewater is ensured.
Further, the first-stage denitrification tank, the aerobic tank, the second-stage denitrification tank and the sedimentation tank are sequentially connected, and the reaction tanks are connected through connectors.
Further, in the step (2), the sewage after the pre-denitrification treatment stays in the aerobic tank for aerobic nitrification treatment for 10.8 to 18 hours; the reflux ratio of the nitrifying liquid, namely the volume ratio of the nitrifying liquid refluxed from the aerobic tank to the first-section denitrification tank to the sewage entering the first-section denitrification tank is 1:1-1: 3. In the step (2), the reflux ratio can be adjusted to 1:1-1:3 by the rotation number of the nitrifying liquid reflux pump. The effective control of the reflux ratio of the nitrifying liquid is the key to realizing the denitrification process of the first step. The reflux ratio is too low, the nitrate nitrogen content in the reflux nitrifying liquid is too low, and organic matters in the inlet water cannot be effectively removed; when the reflux ratio is too high, the over-high dissolved oxygen reflux liquid in the aerobic tank flows into a section of denitrification tank, so that the concentration of the dissolved oxygen in the tank is increased, and the denitrification capability is weakened.
Further, the aeration device in the step (2) is formed by connecting 1 main pipe with the diameter of 4-6 cm and 8 branch pipes with the diameter of 2-4 cm, and each branch pipe is provided with 5 cylindrical aeration heads with the diameter of 0.5-2 cm and the height of 0.5-2 cm; the aperture of the cylindrical aeration head is 80-100 microns. The cylindrical aeration head can form bubbles with high density, large quantity and small enough bubble particle size, the aeration area is the surface area of a cylinder, the aeration area is increased, and the defects of the existing device are overcome. The aeration device is arranged at the bottom of the aerobic tank, and the other end of the aeration device is connected with an aeration pump. The aeration rate of the aeration pump is 70-88L/min.
Further, in the step (3), the time for post denitrification treatment of the wastewater treated by the aerobic tank in the second-stage denitrification tank is 3.6-6 hours.
In order to further strengthen the denitrification effect of the second-stage denitrification tank and remove the nitrogen source in the wastewater, solid slow-release carbon sources can be filled in the spherical filler (fiber ball filter material) of the second-stage denitrification tank to provide carbon sources required by the denitrification reaction and ensure that the denitrification reaction is carried out efficiently, wherein the solid slow-release carbon sources are more than one of polytetramethylene glycol succinate (PBS), poly- β -hydroxybutyric acid (PHB) and old rice.
Preferably, the solid slow-release carbon source is a pellet-type PBS.
Preferably, the solid slow-release carbon source is poly- β -hydroxybutyrate (PHB) and old rice.
PBS is economically attractive for nitrate removal and exhibits comparable insensitivity to pH and DO values, thus providing more stable processing efficiency under different environmental conditions, and PBS polymers perform well even during 230 days of operation.
Further, in the step (4), the time for carrying out precipitation treatment on the wastewater subjected to the post denitrification treatment in a precipitation tank is 2-5 hours; the sludge reflux ratio is the volume ratio of sludge refluxed from the sedimentation tank into the first-stage denitrification tank to sewage entering the first-stage denitrification tank to be 1:1-3: 1.
The sludge precipitated in the sludge sedimentation tank flows back to the first-stage denitrification tank through the sludge backflow system, the sludge age is prolonged, the nitrification capacity of microorganisms is enhanced, the microorganisms can better adhere to and grow on the filler through the sludge backflow, and the denitrification capacity of the wastewater is enhanced.
The reactor developed by the wastewater treatment process comprises a first-stage denitrification tank, an aerobic tank, a second-stage denitrification tank and a sedimentation tank which are sequentially connected, wherein a filler is arranged in the aerobic tank, the filler is a biological combined filler and a fiber ball filter material, and only the fiber ball filter material is arranged in an anoxic tank.
Furthermore, the stirring device is arranged in the first-stage denitrification tank and the second-stage denitrification tank and comprises a controller, a stirring motor, a stirring rod and a stirring head; wherein the rotating speed of the stirring motor is 150-200 r/min.
Furthermore, a pH meter and a dissolved oxygen detector are arranged in the first-stage denitrification tank, the aeration tank and the second-stage denitrification tank, so that the pH and the dissolved oxygen content in the reaction tank can be monitored in real time.
The invention firstly carries out the preposed denitrification process, the wastewater in the water tank enters a section of denitrification tank, nitrate nitrogen which is refluxed by nitrifying liquid is taken as an electron acceptor under the action of facultative anaerobic denitrifying bacteria attached to a fiber ball filter material arranged in the section of denitrification tank, and organic matters in inlet water are taken as an electron donor, so that the nitrate nitrogen is reduced into pollution-free nitrogen, and the nitrogen in the wastewater is removed. The stirring device arranged in the first section of denitrification tank stirs the sludge at the bottom of the tank into a suspension state, and promotes the attachment and growth of microorganisms on the fiber ball filter material. The pH value in the pool is kept between 7.0 and 8.5 by adding sodium bicarbonate into raw water, and the dissolved oxygen is kept below 0.5mg/L by controlling the amount of the refluxed nitrifying liquid.
Then an aerobic nitrification process is carried out, the wastewater flowing out of the first-stage denitrification tank flows into the aerobic tank, and the ammonia nitrogen in the wastewater is oxidized into nitrate nitrogen through the biological combined filler arranged inside the aerobic tank and the nitrifying bacteria attached to the fiber ball filter material. The aeration device designed and installed at the bottom of the aerobic tank is formed by connecting 1 main pipe with the diameter of 4-6 cm and 8 branch pipes with the diameter of 2-4 cm, each branch pipe is provided with 5 cylindrical aeration heads with the diameter of 0.5-2 cm and the height of 0.5-2 cm, the pore diameter of each aeration head is 80-100 microns, bubbles with high density, large quantity and small enough bubble particle size can be formed, the aeration area is the surface area of one cylinder, and uniform aeration at the bottom of the aerobic tank is ensured. And a pH meter and a dissolved oxygen detector which are arranged in the aerobic tank are used for monitoring the pH value and the dissolved oxygen concentration in the tank in real time. The dissolved oxygen was maintained above 3mg/L by adjusting the rotameter.
Then the post-denitrification process is carried out, the wastewater flowing out of the aerobic tank flows into a second-stage denitrification tank, a fiber ball filter material is arranged in the second-stage denitrification tank, nitrate nitrogen flowing out of the aerobic tank is taken as an electron acceptor under the action of facultative anaerobic denitrifying bacteria, and residual organic matters in the wastewater are taken as an electron donor, so that the nitrate nitrogen is reduced into pollution-free nitrogen, and nitrogen elements in the wastewater are further removed.
And finally, a sludge sedimentation process is carried out, sludge sedimentated in the sludge sedimentation tank flows back to a section of denitrification tank through a sludge backflow system, and the sludge backflow enables microorganisms to be attached to and grow on the filler better, so that a sludge-film composite bioreactor is formed, and the denitrification capacity of the wastewater is enhanced. The sludge-membrane composite bioreactor combines the advantages of the traditional activated sludge process and the biofilm process, not only has higher mass transfer efficiency and less investment, but also has uniform distribution of microorganisms and various environmental elements in the tank, longer sludge age, suitability for the growth of nitrobacteria with longer generation period, high sewage treatment efficiency, relatively smaller occupied area and strong impact resistance.
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) the invention provides a two-stage denitrification wastewater denitrification treatment process, which is a method for combining a pre-denitrification process and a post-denitrification process by analyzing and comparing the advantages and the disadvantages of the pre-denitrification process and the post-denitrification process, so that the denitrification treatment in wastewater is removed in the same reactor, and the treatment process is more stable, efficient and energy-saving;
(2) the two-stage denitrification wastewater denitrification treatment process provided by the invention is an integrated reactor developed by applying the wastewater treatment process, and can be effectively combined with the process, so that the denitrification treatment capability of the process is further enhanced; unattended operation can be realized, and the occupied area of the equipment is small, so that the equipment is convenient to move or reuse;
(3) according to the two-stage denitrification wastewater denitrification treatment process provided by the invention, the filter material arranged in the reactor has an ultra-large specific surface area and total porosity, so that a huge space is provided for the attachment and growth of microorganisms;
(4) the invention provides a two-stage denitrification wastewater denitrification treatment process, which is characterized in that PBS, poly- β -hydroxybutyric acid (PHB) and old rice are added into a fiber ball filter material in a two-stage denitrification tank as a solid slow-release carbon source, so that the defect of insufficient carbon source in the two-stage denitrification tank is overcome, the denitrification reaction capability is enhanced, and nitrogen elements in wastewater are further removed.
Drawings
FIG. 1 is a schematic view showing the overall structure of an integrated reactor used in a two-stage denitrification wastewater denitrification process in the example;
FIG. 2 is a schematic structural view of a stirring apparatus in the embodiment;
FIG. 3 is a schematic view of the structure of an aeration apparatus in the example;
wherein, a first-stage denitrification tank 1; a water inlet 11; a first sludge recirculation port 12; a stirring device 13; a stirring motor 131; a stirring rod 132; a stirring head 133; a controller 134; a first connection port 14; a nitrifying liquid reflux port 15; an aerobic tank 2; an aeration device 21; the aeration branch pipes 211; an aeration main pipe 212; aeration holes 213; an aeration pump 214; a second connection port 22; a second-stage denitrification tank 3; a third connection port 31; a sedimentation tank 4; a water outlet 41; a swash plate 42; a second sludge recirculation port 43; a water tank 5; a water inlet pump 6; a sludge reflux pump 7; a nitrifying liquid reflux pump 8; a temperature sensor 9; a heating block 10;
FIG. 4a is a line graph showing the COD removing effect of the wastewater in example 2;
FIG. 4b is a line graph showing the total nitrogen removal effect of wastewater in example 2;
FIG. 4c is a line graph showing the ammonia nitrogen removal effect of the wastewater in example 2;
FIG. 5a is a diagram showing the effect of removing COD from the wastewater of example 3;
FIG. 5b is a graph showing the effect of removing total nitrogen from the wastewater in example 3;
FIG. 5c is a diagram showing the ammonia nitrogen removal effect of sewage in example 3;
FIG. 6a is a diagram showing the effect of removing COD from the wastewater of example 4;
FIG. 6b is a graph showing the effect of total nitrogen removal from wastewater in example 4;
FIG. 6c is the ammonia nitrogen removal effect of the wastewater in example 4.
Detailed Description
The following examples are presented to further illustrate the practice of the invention, but the practice and protection of the invention is not limited thereto. It is noted that the processes described below, if not specifically described in detail, are all realizable or understandable by those skilled in the art with reference to the prior art.
Example 1
The overall structure of the present embodiment is shown in fig. 1, wherein the first-stage denitrification tank 1, the aerobic tank 2, the second-stage denitrification tank 3 and the sedimentation tank 4 are all made of steel, the volume ratio of the first-stage denitrification tank to the aerobic tank to the second-stage denitrification tank is 1:3:1, and the first-stage denitrification tank, the aerobic tank and the second-stage denitrification tank are connected to each other and are communicated with each other through a first connection port 14, a second connection port 22 and a third connection port 31, which have diameters of 2 cm. A water inlet 11 with the diameter of 2 centimeters and a first sludge return opening 12 with the diameter of 2 centimeters are installed on the left side of the first section of denitrification tank, the other end of the water inlet 11 with the diameter of 2 centimeters is connected with a water inlet pump 6, the water inlet pump 6 is connected with a water tank 5, and the other end of the first sludge return opening 12 with the diameter of 5 centimeters is connected with a sludge return pump 7. A stirring device 13 is arranged in the first-stage denitrification tank 1, and a temperature sensor 9 and a heating block 10 are respectively arranged on the inner side walls of the first-stage denitrification tank and the second-stage denitrification tank. A nitrifying liquid reflux port 15 with the diameter of 2 cm is arranged at the left side of the aerobic tank 2, one end of the aerobic tank is connected with the denitrification tank 1, and the other end of the aerobic tank is connected with a nitrifying liquid reflux pump 8. An aeration device 21 is arranged at the bottom of the aerobic tank. The bottom of the sedimentation tank 4 is provided with an inclined plate 42, the right side of the sedimentation tank is provided with a water outlet 41 and a second sludge return port 43, and the other end of the second sludge return port 43 is connected with the sludge return pump 7. The stirring device 13 includes a stirring motor 131, a stirring rod 132, a stirring head 133 and a controller 134, as shown in fig. 2. The stirrer was rotated at 170 rpm. The controller 134 is HH-N05S, HH-N2OS, HH-N4OS, HH-DA10D or MT8516, and it should be noted that the controller is not a main invention of the present invention, and any controller capable of implementing the control function can be used as the controller of this embodiment, and the type of the controller is not limited to the above type, and other types known to those skilled in the art can be used, and the specific type can be determined according to actual situations, and will not be described herein again.
As shown in figures 1 and 3, the aeration device 21 is installed at the bottom of the aerobic tank, and is structured by connecting 1 main aeration pipe 212 with a diameter of 5 cm to 8 branch aeration pipes 211 with a diameter of 3 cm, wherein each branch aeration pipe is provided with 5 cylindrical aeration holes 213 (aeration heads) with a diameter of 1 cm and a height of 1 cm, and the other end of the aeration device is connected to an aeration pump 214. The aeration rate of the aeration pump is 70L/min. The aeration pumps are ACO-006 and ACO-318 during operation, and it should be noted that the aeration pumps are not essential to the present invention, and any aeration pump that can perform an aeration function may be used as the aeration pump of this embodiment.
The executive components comprise a stirring device 13, a water inlet pump 6, a nitrifying liquid reflux pump 8, a sludge reflux pump 7 and an aeration pump 21. In a more preferred embodiment, the aeration pump 21 is selected to be a variable frequency aeration pump.
Temperature sensors, pH meters and dissolved oxygen detectors are arranged in the first-stage denitrification tank and the second-stage denitrification tank, and the pH value and the dissolved oxygen concentration in each tank can be monitored in real time.
The inclined plates are two V-shaped inclined plates, so that the sludge subjected to reflux precipitation can be conveniently collected.
Example 2
The wastewater treated in example 2 is simulated rural domestic sewage. The rural domestic wastewater integrated treatment equipment developed by applying the two-stage denitrification wastewater denitrification treatment process has the water treatment quantity scale of 10L/h, the COD concentration of 150-220mg/L, the ammonia nitrogen concentration of 10-18mg/L and the total nitrogen fluctuation of 20-25 mg/L. The total hydraulic retention time of the integrated reactor designed by the technology of the invention is 20 hours, wherein the first-stage anoxic process is 3.6 hours (pre-denitrification treatment), the aerobic process is 10.8 hours (aerobic nitrification treatment), the second-stage anoxic process is 3.6 hours (post-denitrification treatment), and the sedimentation process is 2 hours (sludge reflux). The rotation speed of the stirrer was set to 150 rpm, and the aeration rate of the aeration pump was set to 70L/min. 6 fiber ball filter materials are respectively arranged in the first-stage denitrification tank, the aerobic tank and the second-stage denitrification tank; the aerobic tank is internally provided with 4 groups of biological combined fillers, each group of biological combined fillers are arranged in the aerobic tank in parallel, each group is provided with 4 strings of biological combined fillers, each string is provided with 4 biological combined fillers, the structure is that a plastic wafer is pressed and buckled into a double-ring large plastic ring, hydroformylation fibers or polyester yarns are pressed on the ring of the ring to uniformly distribute fiber bundles, and the fillers are purchased from Hengyi environmental protection science and technology limited company in Yixing city and have the model of 150 multiplied by 100 mm. The filler is connected by a string, two ends of the string are fixed, so that the biological combined filler can be vertically suspended in the aerobic tank and cannot be suspended on the surface of the aerobic tank, and PBS is added into the two-section denitrification tank to serve as a solid slow-release carbon source. The wastewater treatment process is divided into two working conditions:
the working condition I is as follows: continuous water inflow without backflow is adopted, the water inflow is 3L/h, the removal effect of the detection system on each pollutant index is increased to 6L/h after ten days, the removal effect of the detection system on each pollutant index is increased to 10L/h after ten days, the water inflow is increased again to the design flow and the detection system operates for ten days under the design flow, and the removal effect of each pollutant index is detected. Under the working condition, the first-stage denitrification tank, the aerobic tank, the second-stage denitrification tank and the sedimentation tank are connected in series for operation without backflow. The working condition aims at naturally enriching the surface of the filler with microorganisms, and then forming an anoxic and aerobic biological film in each pool of the reactor, and gradually increasing the water inflow rate is favorable for the attachment and growth of the microorganisms on the filler.
Working conditions are as follows: continuously feeding water and refluxing, wherein the first-stage denitrification tank, the aerobic tank, the second-stage denitrification tank and the sedimentation tank are connected in series for operation, the water is continuously fed at a designed flow rate of 10L/h, the effluent of the aerobic tank is refluxed to the front of the first-stage denitrification tank at a reflux ratio of 100%, the operation is carried out for one month, the time for carrying out sedimentation treatment on sewage in the sedimentation tank is 2 hours, sludge and liquid after the sedimentation treatment are obtained, the sludge is refluxed to the first-stage denitrification tank, and the sludge reflux ratio is 1: 1. The stage is mainly used for domesticating anoxic and aerobic microorganisms in the first-stage denitrification tank and the aerobic tank, so that denitrifying bacteria in the first-stage denitrification tank grow well, and the microorganisms in each reaction tank adapt to the impact of hydraulic load after backflow.
Fig. 4a, 4b and 4c are data diagrams of the present embodiment. FIG. 4a is a line graph showing COD removing effect of sewage; FIG. 4b is a line graph showing the total nitrogen removal effect of wastewater; FIG. 4c is a line graph showing the effect of removing ammonia nitrogen from wastewater; the water outlet value stably reaches the first-class A standard after two months of operation, wherein COD is below 30mg/L, ammonia nitrogen is below 5mg/L, and total nitrogen is below 10 mg/L.
Example 3
The wastewater treated in example 3 is rural domestic sewage in a certain village in Guangdong. The rural domestic wastewater integrated treatment equipment developed by applying the two-stage denitrification wastewater denitrification treatment process has the water treatment quantity scale of 12L/h, the COD concentration of 200-250mg/L, the ammonia nitrogen concentration of 15-23mg/L and the total nitrogen fluctuation of 20-30 mg/L. The total hydraulic retention time of the integrated reactor designed by the technology of the invention is 27 hours, wherein the primary anoxic process is 4.8 hours (preposed denitrification treatment), the aerobic process is 14.4 hours (aerobic nitrification treatment), the secondary anoxic process is 4.8 hours (postpositional denitrification treatment), and the sedimentation process is 3 hours (sludge reflux). The rotation speed of the stirrer was set to 160 rpm, and the aeration rate of the aeration pump was set to 80L/min. 8 fiber ball filter materials are respectively arranged in the first-stage denitrification tank, the aerobic tank and the second-stage denitrification tank; 4 groups of biological combined fillers are arranged in the aerobic tank, each group of biological combined fillers are arranged in the aerobic tank in parallel, 4 strings of biological combined fillers are arranged on each group, each string is provided with 4 biological combined fillers, the biological combined fillers are connected by a string, two ends of the string are fixed, the biological combined fillers can be vertically suspended in the aerobic tank and cannot be suspended on the surface of the aerobic tank, and PHB is added into the two-section denitrification tank to serve as a solid slow-release carbon source. The wastewater treatment process is divided into two working conditions:
the working condition I is as follows: continuous water inflow without backflow is adopted, the water inflow is 4L/h, the removal effect of the detection system on each pollutant index is increased to 8L/h after ten days, the removal effect of the detection system on each pollutant index is increased to 12L/h after ten days, the water inflow is increased again to the design flow, the operation is carried out for ten days under the design flow, and the removal effect of each pollutant index is detected. Under the working condition, the first-stage denitrification tank, the aerobic tank, the second-stage denitrification tank and the sedimentation tank are connected in series for operation without backflow. The working condition aims at naturally enriching the surface of the filler with microorganisms, and then forming an anoxic and aerobic biological film in each pool of the reactor, and gradually increasing the water inflow rate is favorable for the attachment and growth of the microorganisms on the filler.
Working conditions are as follows: continuously feeding water and refluxing, wherein the first-stage denitrification tank, the aerobic tank, the second-stage denitrification tank and the sedimentation tank are connected in series for operation, water is continuously fed at the designed flow rate of 12L/h, and the effluent of the aerobic tank is refluxed to the front of the first-stage denitrification tank at the reflux ratio of 120 percent; settling the sewage in a settling tank for 3 hours to obtain sludge and settled liquid, refluxing the sludge into a first-stage denitrification tank at a sludge reflux ratio of 2:1, and operating for one month. The stage is mainly used for domesticating anoxic and aerobic microorganisms in a first-stage denitrification tank and an aerobic tank, so that the denitrifying microorganisms in the first-stage denitrification tank can grow well, and the microorganisms in each reaction tank are adaptive to the impact of hydraulic load after backflow.
FIG. 5a is a diagram showing the effect of removing COD from the wastewater of example 3; FIG. 5b is a graph showing the effect of removing total nitrogen from the wastewater in example 3; FIG. 5c is a graph showing the ammonia nitrogen removal effect of example 3; as shown in FIG. 5a, FIG. 5b and FIG. 5c, the effluent value after two months of operation stably reaches the first-class A standard, wherein COD is below 35mg/L, ammonia nitrogen is below 5mg/L, and total nitrogen is below 15 mg/L.
Example 4
Example 4 the wastewater treated was domestic wastewater from a community in Guangdong Foshan mountain. The rural domestic wastewater integrated treatment equipment developed by applying the two-stage denitrification wastewater denitrification treatment process has the water treatment quantity scale of 14L/h, the COD concentration of 220-300mg/L, the ammonia nitrogen concentration of 14-27mg/L and the total nitrogen fluctuation of 18-35 mg/L. The total hydraulic retention time of the integrated reactor designed by the invention is 35 hours, wherein the first-stage anoxic process is 6 hours (pre-denitrification treatment), the aerobic process is 18 hours (aerobic nitrification treatment), the second-stage anoxic process is 6 hours (post-denitrification treatment), and the sedimentation process is 5 hours (sludge reflux). The rotation speed of the stirrer is set to 180 revolutions per minute, and the aeration rate of the aeration pump is set to 88L/min. 10 fiber ball filter materials are respectively arranged in the first-stage denitrification tank, the aerobic tank and the second-stage denitrification tank; 4 groups of biological combined fillers are arranged in the aerobic tank, each group of biological combined fillers are arranged in the aerobic tank in parallel, 4 strings of biological combined fillers are arranged on each group, 4 biological combined fillers are arranged in each string and connected by a string, two ends of the string are fixed to ensure that the biological combined fillers can be vertically suspended in the aerobic tank and cannot be suspended on the surface of the aerobic tank, and old rice is added into the two-section denitrification tank to serve as a solid slow-release carbon source. The wastewater treatment process is divided into two working conditions:
the working condition I is as follows: continuous water inflow without backflow is adopted, the water inflow is 4L/h, the removal effect of the detection system on each pollutant index is increased to 9L/h after ten days, the removal effect of the detection system on each pollutant index is increased to 14L/h after ten days, the water inflow is increased again to the design flow and the detection system operates for ten days under the design flow, and the removal effect of each pollutant index is detected. Under the working condition, the first-stage denitrification tank, the aerobic tank, the second-stage denitrification tank and the sedimentation tank are connected in series for operation without backflow. The working condition aims at naturally enriching the surface of the filler with microorganisms, and then forming an anoxic and aerobic biological film in each pool of the reactor, and gradually increasing the water inflow rate is favorable for the attachment and growth of the microorganisms on the filler.
Working conditions are as follows: continuously feeding water and refluxing, wherein the first-stage denitrification tank, the aerobic tank, the second-stage denitrification tank and the sedimentation tank are connected in series for operation, the water is continuously fed at a designed flow rate of 14L/h, effluent of the aerobic tank is refluxed to the front of the first-stage denitrification tank at a reflux ratio of 150%, sewage is subjected to sedimentation treatment in the sedimentation tank for 5 hours to obtain sludge and liquid after sedimentation treatment, the sludge is refluxed to the first-stage denitrification tank at a sludge reflux ratio of 3:1, and the operation is carried out for one month. The stage is mainly used for domesticating anoxic and aerobic microorganisms in a first-stage denitrification tank and an aerobic tank, so that the denitrifying microorganisms in the first-stage denitrification tank can grow well, and the microorganisms in each reaction tank are adaptive to the impact of hydraulic load after backflow.
FIG. 6a is a diagram showing the effect of removing COD from the wastewater of example 4; FIG. 6b is a graph showing the effect of total nitrogen removal from wastewater in example 4; FIG. 6c is a diagram showing the ammonia nitrogen removal effect of sewage in example 4;
as shown in FIG. 6a, FIG. 6b and FIG. 6c, the water outlet value stably reaches the first grade A standard after two months of operation, wherein COD is below 32mg/L, ammonia nitrogen is below 4mg/L, and total nitrogen is below 14 mg/L.
Table 1 below compares the conventional A2O process with the data of the treatment cost of the two-stage denitrification wastewater treatment process provided in example 4, and it can be seen from table 1 that in practical applications, a two-stage denitrification wastewater treatment process can effectively reduce the cost of wastewater treatment.
Table 1: comparison of the data on the treatment costs of the conventional A2O Process and the reactor according to the invention
The above examples are only preferred embodiments of the present invention, which are intended to be illustrative and not limiting, and those skilled in the art should understand that they can make various changes, substitutions and alterations without departing from the spirit and scope of the invention.
Claims (10)
1. A two-stage denitrification wastewater denitrification treatment process is characterized by comprising the following steps:
(1) pre-denitrification treatment: introducing the sewage into a first-stage denitrification tank, wherein a fiber ball filter material and a stirring device are arranged in the first-stage denitrification tank, starting the stirring device to perform pre-denitrification treatment, reducing nitrate nitrogen in the reflux nitrified liquid into pollution-free nitrogen by taking nitrate nitrogen in the reflux nitrified liquid as an electron acceptor and organic matters in the sewage as an electron donor under the action of facultative anaerobic denitrifying bacteria, and removing a nitrogen source in the wastewater to obtain the sewage after the pre-denitrification treatment;
(2) aerobic nitrification treatment: introducing the sewage subjected to the pre-denitrification treatment in the step (1) into an aerobic tank, wherein a filler is arranged inside the aerobic tank, the filler comprises a biological combined filler and a fiber ball filter material, uniformly aerating in an aeration tank through an aeration device, and performing aerobic nitrification treatment, wherein ammonia nitrogen in the sewage subjected to the pre-denitrification treatment is nitrified into nitrate nitrogen by nitrifying bacteria to obtain nitrified liquid and the wastewater treated in the aerobic tank, and returning the nitrified liquid to the primary denitrification tank;
(3) post denitrification treatment: introducing the wastewater treated by the aerobic tank in the step (2) into a second-stage denitrification tank, wherein a fiber ball filter material and a stirring device are arranged in the second-stage denitrification tank, starting the stirring device, and performing post-denitrification treatment by taking nitrate nitrogen flowing out of the aerobic tank as an electron acceptor under the action of facultative anaerobic denitrifying bacteria, and reducing the nitrate nitrogen into pollution-free nitrogen by taking organic matters remaining in the wastewater as an electron donor to obtain the wastewater after the post-denitrification treatment;
(4) sludge backflow: and (4) introducing the wastewater subjected to the post denitrification treatment in the step (3) into a sedimentation tank, performing sedimentation treatment to obtain sludge and liquid subjected to sedimentation treatment, refluxing the sludge into a first-stage denitrification tank, and discharging the liquid subjected to sedimentation treatment to the outside to finish the denitrification treatment of the wastewater.
2. The two-stage denitrification wastewater denitrification process according to claim 1, wherein in the step (1), the time for the wastewater to stay in the one-stage denitrification tank for the pre-denitrification treatment is 3.6-6 hours.
3. The two-stage denitrification wastewater denitrification treatment process according to claim 1, wherein the ball diameters of the fiber ball filter materials in the steps (1), (2) and (3) are all 40-80 mm, the specific surface areas of the fiber ball filter materials are 2800-3500 square meters/cubic meter, and the total porosity of the fiber ball filter materials is 92-95%.
4. The two-stage denitrification wastewater denitrification treatment process as claimed in claim 1, wherein the specific surface area of the biological combination filler in the step (2) is 3300 and 3800 square meters/cubic meter, and the total porosity is more than 99%; the biological combined filler is purchased from Hengshi environmental protection science and technology limited company in Yixing city, and the model is 150 multiplied by 100 mm.
5. The two-stage denitrification wastewater denitrification process according to claim 1, wherein in the step (2), the time for the pre-denitrification wastewater to stay in the aerobic tank for aerobic nitrification is 10.8-18 hours; the reflux ratio of the nitrifying liquid is 1:1-1:3, and the reflux ratio of the nitrifying liquid is the volume ratio of the nitrifying liquid which flows back to the first section of denitrification tank from the aerobic tank to the sewage which enters the first section of denitrification tank.
6. The two-stage denitrification wastewater denitrification process according to claim 1, wherein the aeration device in step (2) is composed of 1 main pipe with a diameter of 4-6 cm and 8 branch pipes with a diameter of 2-4 cm, each branch pipe is provided with 5 cylindrical aeration heads with a diameter of 0.5-2 cm and a height of 0.5-2 cm; the aperture of the cylindrical aeration head is 80-100 microns.
7. The two-stage denitrification wastewater denitrification process according to claim 1, wherein in the step (3), the post denitrification treatment time of the wastewater treated by the aerobic tank in the two-stage denitrification tank is 3.6-6 hours.
8. The two-stage denitrification wastewater denitrification treatment process according to claim 1, wherein the fiber ball filter material in the step (3) can be filled with a solid slow-release carbon source to provide a carbon source required for denitrification reaction, and the solid slow-release carbon source is more than one of polybutylene succinate, poly- β -hydroxybutyric acid and old rice.
9. The two-stage denitrification wastewater denitrification process according to claim 1, wherein in the step (4), the post-denitrification wastewater is subjected to sedimentation treatment in a sedimentation tank for 2-5 hours; the sludge reflux ratio is 1:1-3:1, and the sludge reflux ratio is the volume ratio of sludge refluxed into the first-section denitrification tank from the sedimentation tank to sewage entering the first-section denitrification tank.
10. The process for denitrification treatment of wastewater by two-stage denitrification according to claim 1, wherein the stirring device is installed inside the first-stage denitrification tank and the second-stage denitrification tank, and comprises a controller, a stirring motor, a stirring rod and a stirring head; the pH meter and the dissolved oxygen detector are arranged in the first-stage denitrification tank, the aeration tank and the second-stage denitrification tank, and can monitor the pH value and the dissolved oxygen content in the reaction tank in real time.
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| CN112759177A (en) * | 2020-12-01 | 2021-05-07 | 北京中科圣泰环境科技有限公司 | Deep total nitrogen removal treatment process for industrial wastewater and nitrogen removal device thereof |
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