Iron powder-pyrite coupled algal-bacterial symbiosis sewage treatment device and method

Abstract

The invention discloses an iron powder-pyrite coupled algal-bacterial symbiosis sewage treatment device and method.The iron powder-pyrite coupled algal-bacterial symbiosis sewage treatment device comprises an algal-bacterial symbiosis reactor body, an iron powder-pyrite assembly, a water inlet pump, an aeration system and a PLC control system; an inclined plate settling zone, a sludge settling zone and a reactor water outlet are arranged at the top, conversion of organic matters and ammonia nitrogen is realized through photosynthetic oxygen production, effluent from the top of the algal-bacterial symbiotic reactor is pumped into an iron powder-pyrite assembly by an external circulating pump, nitrate is reduced into nitrogen through sulfur autotrophic denitrifying bacteria, and phosphorus is removed through iron flocculent precipitation. The invention has the following beneficial effects: the algal-bacterial symbiotic system can utilize light energy to carry out photosynthesis, does not need a large amount of aeration, and reduces aeration energy consumption; the iron powder is combined with a sulfur autotrophic denitrification system, so that the long-term operation performance of pyrite autotrophic denitrification can be effectively improved, nitrogen and phosphorus removal is enhanced, and generation of sulfate radicals is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage biological treatment, and particularly relates to an iron powder - pyrite coupled bacteria - algae symbiotic sewage treatment device and method. Background Technique

[0002] At present, the vast majority of urban sewage treatment plants in China adopt biological treatment technologies centered on the activated sludge method. Through the metabolic activities of activated sludge microorganisms, the decomposition and transformation of carbon, nitrogen, and phosphorus in sewage are realized, which has the advantages of mature technology and stable effluent. However, problems such as aeration energy consumption and denitrification carbon source addition lead to high operating costs of sewage treatment plants. In recent years, the bacteria - algae symbiotic system has shown unique ecological complementary advantages. This technology realizes the efficient removal of pollutants through the synergistic metabolism of algae and bacteria: algae release oxygen through photosynthesis, replacing traditional aeration equipment, which can reduce energy consumption by more than 50%; at the same time, the carbon dioxide produced by bacteria decomposing organic matter provides a carbon source for the growth of algae, forming a self - sufficient material cycle. In addition, the residual biomass of the bacteria - algae symbiotic system is rich in proteins and lipids, which can be used as raw materials for biofuels, animal feeds, or organic fertilizers to achieve resource utilization, while the excess sludge of the traditional activated sludge method is difficult to directly recycle due to problems such as heavy metal enrichment.

[0003] In terms of nitrogen and phosphorus removal, although algae can directly absorb ammonia nitrogen and phosphate to synthesize biomass, and cooperate with the nitrification - denitrification of bacteria to improve the nitrogen and phosphorus removal efficiency of the system, the absorption rate of microalgae for nitrogen and phosphorus is relatively slow, and additional nitrogen and phosphorus removal units are needed. Compared with traditional heterotrophic denitrification, sulfur - autotrophic denitrification mediated by pyrite uses pyrite as an electron donor. Under anoxic conditions, microorganisms use it for denitrification to convert nitrate into nitrogen. By further mixing pyrite with iron powder, the nitrogen and phosphorus removal of the system can be effectively improved.

[0004] In view of this, it is necessary to develop a device and method for an iron powder - pyrite coupled bacteria - algae symbiotic system to more efficiently and comprehensively reduce pollutants such as carbon, nitrogen, and phosphorus in the effluent. Summary of the Invention

[0005] To solve the deficiencies of the prior art, the present invention provides an external - circulation iron powder - pyrite component coupled bacteria - algae symbiotic sewage treatment device and method, which can solve the problems of existing sewage aeration energy consumption and denitrification carbon source addition. The specific technical solutions are as follows:

[0006] On the one hand, the present invention provides an iron powder - pyrite coupled bacteria - algae symbiotic sewage treatment device, including a bacteria - algae symbiotic reactor main body, an iron powder - pyrite component, a feed pump, an aeration system, and a PLC system;

[0007] Preferably, the main body of the bacteria-algae symbiotic reactor is internally provided with fixed biofilm fillers and LED light sources, and is provided with an inclined plate sedimentation area, a sludge sedimentation area and a reactor water outlet at the top. The sludge sedimentation area is provided with a circulating water outlet, and the circulating water outlet is below the liquid level of the overflow weir. The bottom of the reactor main body is provided with a reactor water inlet, and four sampling ports are arranged on one side of the reactor main body, and switch valves are installed at the sampling ports;

[0008] Preferably, the iron powder-pyrite component is placed inside the main body of the bacteria-algae symbiotic reactor, including a component water inlet, a component water outlet and an external circulation pump. The circulating water outlet is communicated with the component water inlet through a pipeline, and the external circulation pump pumps the reactor effluent into the component for denitrification and phosphorus removal reactions, and the effluent after the reaction is discharged into the reactor main body through the component water outlet;

[0009] Preferably, the aeration system includes aeration heads, an aeration pump and a gas flow meter. The aeration heads are arranged at the bottom of the reactor and are connected to the aeration pump and the gas flow meter through pipelines;

[0010] Preferably, the PLC control system includes a PLC controller, an on-line dissolved oxygen probe and a dissolved oxygen tester, which monitor the dissolved oxygen concentration of the system and real-time feedback the aeration volume of the system to adjust the dissolved oxygen concentration of the system;

[0011] Preferably, in a kind of iron powder-pyrite coupled bacteria-algae symbiotic sewage treatment device, microalgae are attached to the outside of the fixed biofilm filler, and activated sludge is attached to the inside;

[0012] Preferably, in a kind of iron powder-pyrite coupled bacteria-algae symbiotic sewage treatment device, the dissolved oxygen is jointly regulated by the oxygen production of microalgae through photosynthesis and the aeration heads, and the concentration is controlled at 2-3 mg / L.

[0013] On the other hand, the present invention also provides a method for sewage treatment using an iron powder-pyrite coupled bacteria-algae symbiotic sewage treatment device, including the following steps:

[0014] (1) The reactor operates in a continuous flow mode, inoculating 0.5-1.0 g / L of Chlorella vulgaris and 3-5 g / L of activated sludge. The feed pump feeds the sewage into the reactor, and at the same time, the aeration pump and the LED light source are turned on. After 15-30 days of operation, the film hanging is successful. The microalgae grow on the outer layer of the biofilm for photosynthesis to produce oxygen, and the activated sludge grows on the inner layer of the biofilm to achieve nitrification and denitrification. Gradually, photosynthesis replaces mechanical aeration until the mechanical aeration is completely stopped;

[0015] (2) The external circulation pump pumps the water discharged from the top of the algal-bacterial symbiotic reactor into the iron powder-pyrite component. The flow rate ratio of the external circulation pump to the influent pump is adjusted according to the target water quality of the effluent. Nitrate is reduced to nitrogen by sulfur autotrophic denitrifying bacteria, and phosphorus is removed by iron flocculation precipitation. After being treated by the sulfur component, the sewage is discharged through the outlet of the sulfur component and enters the reactor main body again, completing a cycle of sewage treatment and finally being discharged through the outlet at the top of the reactor.

[0016] Preferably, in the method for sewage treatment using an iron powder-pyrite coupled algal-bacterial symbiotic sewage treatment device, the intensity of the LED light source is 2000 - 4000 lux.

[0017] Preferably, in the method for sewage treatment using an iron powder-pyrite coupled algal-bacterial symbiotic sewage treatment device, when treating domestic sewage, the phosphorus concentration in the effluent is less than 0.5 mg / L, and the total nitrogen in the effluent is less than 12 mg / L.

[0018] Preferably, in the method for sewage treatment using an iron powder-pyrite coupled algal-bacterial symbiotic sewage treatment device, the volume ratio of iron powder in the component is 10% - 30%, the replacement cycle of iron powder and pyrite is 20 - 50 days, and the replacement ratio each time is 10% - 30%.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] (1) The algal-bacterial symbiotic sewage treatment is ecologically friendly, can utilize light energy for photosynthesis, does not require a large amount of aeration, and reduces energy consumption. It has low cost, the system construction and operation costs are not high, and the generated algal biomass has economic value. In addition, the system has various forms, such as biofilm reactors and open ponds, which can be selected according to the actual situation and has broad application prospects.

[0021] (2) Compared with the existing pyrite autotrophic denitrification system, the present invention combines iron powder with the pyrite autotrophic denitrification system. The reaction product ferric iron of iron can promote the autoxidation of pyrite, improve the long-term operation performance of pyrite autotrophic denitrification, has the advantages of strengthening nitrogen and phosphorus removal, and reducing the generation of sulfate radicals. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0023] Figure 1Schematic diagram of a sewage treatment device with the symbiotic coupling of iron powder and pyrite with bacteria and algae provided by the present invention. Reference numerals shown in the drawings: main body of the bacteria-algae symbiotic reactor (1), iron powder-pyrite component (2), inlet water pump (3), fixed biological film filler (4), LED light source (5), inclined plate sedimentation area (6), sludge sedimentation area (7), reactor water outlet (8), circulating water outlet (9), reactor water inlet (10), switch valve (11), component water inlet (12), component water outlet (13), external circulation pump (14), aeration head (15), aeration pump (16), gas flowmeter (17), PLC controller (18), on-line dissolved oxygen probe (19) and dissolved oxygen tester (20). Detailed implementation manners

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention and should not be used to limit the protection scope of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the protection scope of the present invention.

[0025] Embodiment 1: A sewage treatment device with the symbiotic coupling of iron powder and pyrite with bacteria and algae

[0026] As Figure 1 shown, a sewage treatment device with the symbiotic coupling of iron powder and pyrite with bacteria and algae includes a main body of the bacteria-algae symbiotic reactor 1, an iron powder-pyrite component 2, an inlet water pump 3, an aeration system and a PLC system; the main body of the bacteria-algae symbiotic reactor 1 is internally provided with a fixed biological film filler 4 and an LED light source 5, and is provided with an inclined plate sedimentation area 6, a sludge sedimentation area 7 and a reactor water outlet 8 at the top. The sludge sedimentation area 7 is provided with a circulating water outlet 9, and the circulating water outlet 9 is below the liquid level of the overflow weir. The bottom of the main body of the bacteria-algae symbiotic reactor 1 is provided with a reactor water inlet 10, and four sampling ports are arranged on one side of the main body of the bacteria-algae symbiotic reactor 1, and switch valves 11 are arranged on all the sampling ports;

[0027] The iron powder-pyrite component 2 is placed inside the main body of the bacteria-algae symbiotic reactor 1 and includes a component water inlet 12, a component water outlet 13 and an external circulation pump 14. The circulating water outlet 9 is communicated with the component water inlet 12 through a pipeline. The external circulation pump 14 pumps the reactor effluent into the iron powder-pyrite component 2 for denitrification and phosphorus removal reactions, and the effluent after the reaction is discharged into the main body of the bacteria-algae symbiotic reactor 1 through the component water outlet 13;

[0028] The aeration system includes an aeration head 15, an aeration pump 16 and a gas flowmeter 17. The aeration head 15 is arranged at the bottom of the reactor and is connected to the aeration pump 16 and the gas flowmeter 17 through pipelines;

[0029] The PLC control system includes a PLC controller 18, an on-line dissolved oxygen probe 19, and a dissolved oxygen tester 20, which monitor the dissolved oxygen concentration in the system and provide real-time feedback on the aeration volume of the system to adjust the dissolved oxygen concentration in the system.

[0030] In the above iron powder - pyrite coupled bacteria - algae symbiotic sewage treatment device, the bacteria - algae symbiosis generates oxygen through photosynthesis, reducing the energy consumption of mechanical aeration. In the iron powder - pyrite component 2, pyrite is used as the electron donor and nitrate as the electron acceptor, increasing the total nitrogen removal rate of the system. In addition, iron powder can remove phosphate ions through flocculation precipitation.

[0031] Example 2: A method based on an iron powder - pyrite coupled bacteria - algae symbiotic sewage treatment device

[0032] The process in this example is based on the device in Example 1 and includes the following steps:

[0033] (1) The reactor operates in a continuous flow mode, inoculating 0.5 - 1.0 g / L of Chlorella vulgaris and 3 - 5 g / L of activated sludge. The influent pump 3 feeds sewage into the reactor. At the same time, the aeration pump 16 and the LED light source 5 are turned on. After 15 - 30 days of operation, successful biofilm formation is achieved. The microalgae grow on the outer layer of the biofilm to produce oxygen through photosynthesis, and the activated sludge grows on the inner layer of the biofilm to achieve nitrification and denitrification. Gradually, photosynthesis replaces mechanical aeration until mechanical aeration is completely stopped.

[0034] (2) The external circulation pump 14 pumps the effluent from the top of the bacteria - algae symbiotic reactor main body 1 into the iron powder - pyrite component 2. The flow rate ratio of the external circulation pump 14 to the influent pump 3 is adjusted according to the target water quality of the effluent. Nitrate is reduced to nitrogen gas by sulfur autotrophic denitrifying bacteria, and phosphorus is removed by iron flocculation precipitation. After being treated by the iron powder - pyrite component 2, the sewage is discharged through the component outlet 13 and re - enters the bacteria - algae symbiotic reactor main body 1 to complete a cycle of sewage treatment, and finally is discharged through the outlet 8 at the top of the reactor.

[0035] To further illustrate the detailed process of this process, it is described in detail through a control experiment:

[0036] (1) Simulated sewage

[0037] The reactor is started with simulated sewage, using glucose as the simulated carbon source, NH 4 Cl as the simulated nitrogen source, and KH 2 PO 4 as the simulated phosphorus source. The quality of the artificial prepared water used is as follows: influent COD 250 mg / L, ammonia nitrogen concentration 30 mg / L, P concentration 3 mg / L, and the influent pH is controlled at 7.5 by adding sodium bicarbonate.

[0038] (2) Startup stage

[0039] The experiment was divided into two groups: the experimental group was the algal-bacterial symbiotic reactor with the addition of iron powder-pyrite components, and the control group was the algal-bacterial symbiotic reactor without the addition of iron powder-pyrite components.

[0040] Both reactors in the two groups were made of acrylic material, with a cylindrical structure, a diameter of 12 cm, and a height of 50 cm at the liquid outlet. The main body of the algal-bacterial symbiotic reactor was internally equipped with fixed biofilm fillers. The fillers were made of square sponge material, with a length of 20 mm, and were fixed by inserting iron wires. The filling ratio of the fillers was 20%, the inoculated activated sludge concentration was about 4 g / L, and the chlorella was 1 g / L. There were inclined plate sedimentation areas and sludge sedimentation areas at the top of the reactor, and the effluent flowed out through the overflow weir of the sedimentation area. The influent pump was used to introduce sewage into the reactor. At the same time, the aeration pump and the LED light source were turned on. The light source intensity was 2500 lux. After 20 days of operation, successful biofilm formation was achieved. Microalgae grew on the outer layer of the biofilm for photosynthesis to produce oxygen, and activated sludge grew on the inner layer of the biofilm to achieve nitrification and denitrification. Gradually, photosynthesis replaced mechanical aeration until mechanical aeration was completely stopped, and the dissolved oxygen concentration was controlled at 2 mg / L.

[0041] In the experimental group reactor, the iron powder-pyrite component was placed inside the main body of the algal-bacterial symbiotic reactor, with a volume of about 15% of the volume of the reactor main body. It was internally filled with iron powder and pyrite. The volume of iron powder accounted for 20%, and the volume of pyrite accounted for 80%. The component was inoculated with 4000 mg / L of sulfur autotrophic denitrifying sludge. The external circulation pump pumped the effluent from the top of the algal-bacterial symbiotic reactor into the iron powder-pyrite component. The flow rate ratio of the external circulation pump to the influent pump was controlled at 1:1. Nitrate was reduced to nitrogen by sulfur autotrophic denitrifying bacteria, and phosphorus was removed by iron flocculation precipitation. After being treated by the sulfur component, the sewage was discharged through the outlet of the sulfur component and re-entered the reactor main body to complete a cycle of sewage treatment, and finally was discharged through the outlet at the top of the reactor.

[0042] After the two sets of devices treated the synthetic sewage respectively, the treatment data were shown in Table 1 below. It can be seen from the results that by using the iron powder-pyrite coupled algal-bacterial symbiotic reactor of the present invention, the removal rates of total nitrogen and total phosphorus were maintained at a relatively high level, and there was a significant removal efficiency.

[0043] Table 1 Comparison of treatment effects of two groups of test devices (average value of 5 groups of data selected)

[0044]

[0045] The above specific embodiments are only specific cases of the present invention. The patent protection scope of the present invention includes, but is not limited to, the product forms and styles of the above specific embodiments. Any appropriate changes or modifications made by any person of ordinary skill in the art that meet the claims of the present invention shall fall within the patent protection scope of the present invention.

Claims

1. An iron powder-pyrite coupled bacteria-algae symbiotic sewage treatment device, characterized in that: The invention comprises a bacteria-algae symbiotic reactor body (1), an iron powder-pyrite component (2), a water inlet pump (3), an aeration system and a PLC system; the bacteria-algae symbiotic reactor body (1) has a built-in fixed biofilm filler (4) and an LED light source (5); a top is provided with an inclined plate sedimentation area (6), a sludge settling area (7) and a reactor water outlet (8); the sludge settling area (7) is provided with a circulating water outlet (9), the circulating water outlet (9) is below the liquid level of the overflow weir; a reactor water inlet (10) is provided at the bottom of the reactor body; four sampling ports are provided on one side of the reactor body, and switch valves (11) are provided at the sampling ports; The iron powder-pyrite component (2) is placed inside the bacteria-algae symbiotic reactor body (1), and comprises a component water inlet (12), a component water outlet (13) and an external circulation pump (14); the circulation water outlet (9) is connected to the component water inlet (12) through a pipeline; the external circulation pump (14) draws the reactor outlet water into the component and performs a denitrification and dephosphorization reaction; the outlet water after the reaction is discharged into the bacteria-algae symbiotic reactor body (1) through the component water outlet (13); The aeration system comprises an aeration head (15), an aeration pump (16) and a gas flow meter (17); the aeration head (15) is arranged at the bottom of the reactor and connected to the aeration pump (16) and the gas flow meter (17) via a pipeline; The PLC control system comprises a PLC controller (18), an online dissolved oxygen probe (19) and a dissolved oxygen tester (20), which monitors the dissolved oxygen concentration of the system and provides real-time feedback of the aeration volume of the system to adjust the dissolved oxygen concentration of the system.

2. The iron powder-pyrite coupled bacteria-algae symbiotic sewage treatment device according to claim 1 is characterized in that: The fixed biofilm filler (4) has microalgae attached to the outside and activated sludge attached to the inside.

3. The iron powder-pyrite coupled bacteria-algae symbiotic sewage treatment device according to claim 1 is characterized in that: The dissolved oxygen is regulated by the oxygen production by photosynthesis of microalgae and the aeration head (15), and the concentration is controlled at 2-3 mg / L.

4. The method for treating sewage using an iron powder-pyrite coupled bacteria-algae symbiotic sewage treatment device according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) The reactor adopts a continuous flow operation mode, inoculated with 0.5-1.0 g / L of Chlorella and 3-5 g / L of activated sludge, and the inlet pump (3) passes the sewage into the reactor. At the same time, the aeration pump (16) and the LED light source (5) are turned on. After 15-30 days of operation, the biofilm is successfully formed. The microalgae grow in the outer layer of the biofilm to produce oxygen through photosynthesis, and the activated sludge grows in the inner layer of the biofilm to achieve nitrification and denitrification. The mechanical aeration is gradually replaced by photosynthesis until the mechanical aeration is completely stopped. (2) The external circulation pump (14) draws the water from the top of the bacteria-algae symbiotic reactor body (1) into the iron powder-pyrite component (2). The flow rate ratio of the external circulation pump (14) and the flow rate of the water inlet pump (3) is adjusted according to the water quality of the effluent. Nitrates are reduced to nitrogen gas by sulfur autotrophic denitrifying bacteria, and phosphorus is removed by iron flocculation and precipitation. After being treated by the iron powder-pyrite component (2), the sewage is discharged through the component outlet (13) and enters the bacteria-algae symbiotic reactor body (1) again, completing a cycle of sewage treatment and finally discharged through the reactor outlet (8).

5. The method for treating sewage using an iron powder-pyrite coupled bacteria-algae symbiotic sewage treatment device according to any one of claims 1 to 4, characterized in that: The intensity of the LED light source (5) is 2000-4000 lux.

6. The method for treating sewage using an iron powder-pyrite coupled bacteria-algae symbiotic sewage treatment device according to any one of claims 1 to 4, characterized in that: When treating domestic sewage, the effluent phosphorus concentration is less than 0.5 mg / L, and the effluent total nitrogen is less than 12 mg / L.

7. The method for treating sewage using an iron powder-pyrite coupled bacteria-algae symbiotic sewage treatment device according to any one of claims 1 to 4, characterized in that: The proportion of iron powder in the component volume is 10%-30%. The replacement cycle of iron powder and pyrite is 20-50 days, and the replacement ratio is 10%-30% each time.

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