Rural sewage treatment system with low carbon emission

Abstract

The utility model relates to a rural sewage treatment system with low carbon emission. The method is suitable for the environment-friendly fields of sewage treatment, pollution reduction and carbon reduction. The technical scheme adopted by the utility model is that the system comprises a water inlet pool; the anaerobic unit is used for providing an anaerobic environment; the aerobic I unit is used for providing an aerobic environment with the dissolved oxygen concentration higher than a preset value; the anoxic I unit is used for providing an anoxic environment; the anoxic II unit is used for providing an anoxic environment so as to remove nitrite nitrogen, nitrate nitrogen and ammonia nitrogen through denitrification and anaerobic ammonia oxidation reaction; the aerobic II unit is used for providing an aerobic environment with the dissolved oxygen concentration higher than a preset value, so that aerobic phosphorus removal and ammonia nitrogen oxidation reaction are facilitated; the secondary sedimentation tank unit is used for mud-water separation, and bottom sludge flows back to the anaerobic unit; the water outlet tank is used for receiving clarified effluent separated by the secondary sedimentation tank unit; and the first dosing unit is arranged corresponding to the anaerobic unit and is used for adding nano ferroferric oxide into the anaerobic unit.

Description

Technical Field

[0001] The utility model relates to a rural sewage treatment system with low carbon emission, which is applicable to environmental protection fields such as sewage treatment and pollution reduction and carbon reduction. Background Art

[0002] Rural sewage has large fluctuations in water volume and water quality, and the existing sewage treatment process has poor adaptability and process stability. When the water volume is low and the concentration of organic matter in the influent is low, excessive aeration is common, resulting in low total nitrogen removal rate, high energy consumption, and high carbon emissions. Therefore, it is necessary to explore a sewage treatment method and device with strong adaptability, strong stability, low energy consumption, and low carbon emissions based on the characteristics of rural sewage water volume and water quality.

[0003] Carbon emissions from sewage treatment include direct emissions and indirect emissions. The greenhouse gases emitted by direct carbon emissions are mainly methane and nitrous oxide, and indirect carbon emissions mainly include electricity consumed by aeration, reflux and other equipment, as well as carbon emissions generated by the preparation and transportation of chemical agents. Therefore, in order to reduce carbon emissions from sewage treatment, it is necessary to take into account both direct and indirect carbon emissions, and to take into account the simultaneous reduction of both types of carbon emissions. Utility Model Content

[0004] The technical problem to be solved by the utility model is: to provide a rural sewage treatment system with low carbon emission in view of the above-mentioned existing problems.

[0005] The technical solution adopted by the utility model is: a rural sewage treatment system with low carbon emission, characterized in that it includes:

[0006] Inlet pool;

[0007] The anaerobic unit is used to provide an anaerobic environment to utilize saccharide-accumulating bacteria and phosphate-accumulating bacteria to transform the internal carbon source, quickly remove organic matter, and simultaneously release phosphorus;

[0008] Aerobic I unit is used to provide an aerobic environment with a dissolved oxygen concentration higher than a preset value, so as to facilitate aerobic phosphorus removal and ammonia nitrogen oxidation reactions, oxidize ammonia nitrogen into nitrite nitrogen and nitrate nitrogen, and use polyphosphate bacteria to absorb phosphorus;

[0009] Anoxic I unit, used to provide anoxic environment to facilitate the removal of nitrite nitrogen, nitrate nitrogen and ammonia nitrogen through denitrification and anaerobic ammonium oxidation reactions;

[0010] Anoxic II unit, used to provide anoxic environment to facilitate the removal of nitrite nitrogen, nitrate nitrogen and ammonia nitrogen through denitrification and anaerobic ammonium oxidation reactions;

[0011] Aerobic II unit is used to provide an aerobic environment with a dissolved oxygen concentration higher than a preset value to facilitate aerobic phosphorus removal and ammonia nitrogen oxidation reactions;

[0012] Secondary sedimentation tank unit, used for mud-water separation, with the bottom sludge returned to the anaerobic unit;

[0013] An outlet tank, used to receive the clarified water separated by the secondary sedimentation tank unit;

[0014] The first dosing unit is arranged corresponding to the anaerobic unit and is used for adding nano-ferroferric oxide into the anaerobic unit.

[0015] Ferroferric oxide is conductive and can improve the electron transfer ability of microorganisms. In the process of biological denitrification, the carbon source is quickly utilized by heterotrophic bacteria, and the electrons are transferred to N2O reducing functional bacteria through the interspecies electron transfer process, thereby promoting the conversion and utilization of organic matter and the reduction of N2O.

[0016] Also includes:

[0017] The second dosing unit is provided corresponding to the anoxic unit I and is used to add nano-iron tetroxide to the anoxic unit I;

[0018] The third dosing unit is arranged corresponding to the anoxic II unit and is used for adding nano-ferroferric oxide into the anoxic II unit.

[0019] The anaerobic unit, aerobic I unit, anoxic I unit and aerobic II unit adopt activated sludge reactors;

[0020] The anoxic II unit adopts a fixed bed biofilm reactor, in which a composite filler is used, the filling rate is 60-80%, and a metal frame is used to fix the reactor.

[0021] The anaerobic unit, aerobic I unit, anoxic I unit, anoxic II unit and aerobic II unit are inoculated with common activated sludge; the anoxic I unit and anoxic II unit are inoculated with anaerobic ammonium oxidation sludge.

[0022] The dissolved oxygen concentration in the aerobic I unit is 0.2-0.5 mg / L; the dissolved oxygen concentration in the aerobic II unit is 4.0-5.0 mg / L.

[0023] The dosage of the nano-ferroferric oxide is 3-5 g / L.

[0024] The pool capacity ratios of aerobic unit I: anoxic unit I: anoxic unit II: aerobic unit II are 1:2:2:2:0.5 respectively.

[0025] The composite filler comprises polypropylene plastic, polyurethane sponge and fiber filaments.

[0026] The beneficial effect of the utility model is that the utility model adds nano-ferroferric tetroxide to the anaerobic unit, the anoxic I unit, the anoxic II unit, etc. through the dosing unit, and utilizes the nano-ferroferric tetroxide to reduce the emission of methane and nitrous oxide in the sewage treatment process, thereby reducing direct carbon emissions.

[0027] The utility model introduces anaerobic ammonium oxidation reaction in the sewage treatment process by inoculating anaerobic ammonium oxidation sludge in the anoxic I unit and the anoxic II unit, utilizes the characteristic of small oxygen demand of the anaerobic ammonium oxidation reaction, reduces aeration energy consumption in the sewage treatment process, and further realizes reduction of indirect carbon emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a sewage treatment system in the embodiment.

[0029] Figure 2 The control test results in the examples are nitrate removal and greenhouse gas emission flux (a without adding nano-ferroferric oxide; b with adding nano-ferroferric oxide).

[0030] 1. Inlet tank; 2. Anaerobic unit; 3. Aerobic I unit; 4. Anoxic I unit; 5. Anoxic II unit; 6. Aerobic II unit; 7. Secondary sedimentation tank unit; 8. Outlet tank. DETAILED DESCRIPTION

[0031] Example 1: Figure 1 As shown, this embodiment is a rural sewage treatment system with low carbon emissions, which includes an inlet tank, an anaerobic unit, an aerobic I unit, an anoxic I unit, an anoxic II unit, an aerobic II unit, a secondary sedimentation tank unit and an outlet tank, which are arranged in sequence along the sewage flow direction.

[0032] In this example, the inlet pool is used to collect the sewage to be treated; the anaerobic unit is used to provide an anaerobic environment to remove organic matter in the sewage, and utilize saccharide-accumulating bacteria and polyphosphate-accumulating bacteria to transform the internal carbon source, so that the organic matter is quickly removed and phosphorus is released simultaneously.

[0033] In this embodiment, the aerobic I unit is used to provide an aerobic environment with a dissolved oxygen concentration higher than a preset value to facilitate aerobic phosphorus removal and ammonia nitrogen oxidation reactions. The dissolved oxygen in the sewage is increased through aeration, organic matter is further removed, and ammonia nitrogen is oxidized into nitrite nitrogen and nitrate nitrogen. Polyphosphate bacteria are used to achieve excessive phosphorus absorption under aerobic conditions.

[0034] In this example, the anoxic I unit is used to provide an anoxic environment to remove nitrate, residual ammonia nitrogen and residual phosphate. The internal carbon source generated by the anaerobic unit is used for denitrification under anoxic conditions, and the anaerobic ammonium oxidation reaction is used to achieve the simultaneous removal of nitrate and residual ammonia nitrogen. At the same time, denitrification and phosphorus removal reactions can occur to further remove nitrate and phosphate.

[0035] In this example, the anoxic II unit is used to provide an anoxic environment to remove the remaining small amount of nitrate and ammonia nitrogen. Unlike the anoxic I unit, further removal of pollutants can occur under lower substrate concentration conditions.

[0036] In this embodiment, the aerobic II unit is used to provide an aerobic environment with a dissolved oxygen concentration higher than a preset value, so as to further oxidize and remove residual ammonia nitrogen and organic matter, and ensure that the ammonia nitrogen and COD concentrations in the effluent meet the discharge standards.

[0037] In this embodiment, the secondary sedimentation tank unit is used to separate mud and water, the clarified water is sent to the effluent tank, and the bottom sludge is returned to the anaerobic unit.

[0038] In this example, the proportions of anaerobic: aerobic I: anoxic I: anoxic II: aerobic II are 1:2:2:2:0.5 respectively. Compared with the traditional anaerobic-anoxic-aerobic sewage treatment process, the aerobic tank in this method has a small proportion and a large proportion of anoxic tank, which can effectively reduce the energy consumption of aeration fans. The nitrification liquid reflux from the aerobic tank to the anoxic tank in the traditional anaerobic-anoxic-aerobic sewage treatment process is eliminated, saving the energy consumption generated by the reflux pump.

[0039] In this example, different dissolved oxygen concentrations are controlled in the aerobic I and aerobic II units. The dissolved oxygen concentration in aerobic I is 0.2-0.5 mg / L; the dissolved oxygen concentration in aerobic II is 4.0-5.0 mg / L.

[0040] In this embodiment, anaerobic, aerobic I, anoxic I and aerobic II are activated sludge reactors, and anoxic II is a fixed bed biofilm reactor. Biofilm can proliferate and enrich long sludge age microorganisms, such as autotrophic bacteria and archaea. Such microorganisms can utilize low-concentration substrates, have strong substrate affinity, and transform low-concentration pollutants. Anoxic II uses a combination of fillers such as polypropylene plastic, polyurethane sponge, and fiber filaments, with a filling rate of 60-80%, and is fixed in the reaction tank using a metal frame.

[0041] In this example, the reactor was inoculated with ordinary activated sludge, and a small amount of anaerobic ammonium oxidation sludge was inoculated in anoxic I and anoxic II. After inoculation, the sludge concentration in the reactor was 3-5 gMLSS / L. The mass proportion of anaerobic ammonium oxidation sludge in anoxic I and anoxic II was about 30%-50%.

[0042] In this embodiment, different dissolved oxygen concentrations are controlled in the aerobic I and aerobic II units, the dissolved oxygen concentration in aerobic I is 0.2-0.5 mg / L, and the dissolved oxygen concentration in aerobic II is 4.0-5.0 mg / L. In this embodiment, the sludge return ratio of the secondary sedimentation tank is 30%-50%.

[0043] Through testing, it was found that in the anaerobic-aerobic-anoxic-aerobic treatment process, the front anaerobic section is the main greenhouse gas emission unit, and CH4 and N2O gas emissions account for more than 70% of the entire treatment process. The generation of CH4 comes from the conversion of organic matter under anaerobic conditions, and N2O comes from the denitrification reaction of residual NO3- in the return sludge. Therefore, in this embodiment, a first dosing unit is set corresponding to the anaerobic unit, and nano-ferroferric oxide is added to the anaerobic unit through the first dosing unit to reduce greenhouse gas emissions. The dosage of nano-ferroferric oxide is determined according to the volume of sewage and is 3-5g / L.

[0044] Example 2: This example is basically the same as Example 1, except that in this example, a second dosing unit and a third dosing unit are respectively provided corresponding to the anoxic I unit and the anoxic II unit, and nano-ferroferric oxide is added to the anoxic I unit through the second dosing unit, and nano-ferroferric oxide is added to the anoxic II unit through the third dosing unit.

[0045] In this embodiment, when nano-ferroferric oxide is added to the anaerobic and anoxic tanks, the emission of methane and nitrous oxide is reduced simultaneously. Figure 2 As shown, the nitrate reduction rates of the control group and the nano-ferroferric oxide addition group (dosage of 5g / L) were 1.54 and 1.75gN / (gVSS h), respectively, and the nitrate removal rate increased by 14%. The methane (CH4) emission factors of the control group and the nano-ferroferric oxide addition group were 0.02% and 0.007%, respectively. The emission factors of nitrous oxide (N2O) of the control group and the nano-ferroferric oxide addition group were 0.1% and 0.07%, respectively. The addition of nano-ferroferric oxide reduced CH4 and N2O emissions by 65% ​​and 30%, respectively. Therefore, the addition of nano-ferroferric oxide can simultaneously increase the nitrate reduction rate and reduce greenhouse gas emissions.

[0046] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A rural sewage treatment system with low carbon emissions, characterized in that: include: Inlet pool; The anaerobic unit is used to provide an anaerobic environment to utilize saccharide-accumulating bacteria and phosphate-accumulating bacteria to transform the internal carbon source, quickly remove organic matter, and simultaneously release phosphorus; Aerobic I unit is used to provide an aerobic environment with a dissolved oxygen concentration higher than a preset value, so as to facilitate aerobic phosphorus removal and ammonia nitrogen oxidation reactions, oxidize ammonia nitrogen into nitrite nitrogen and nitrate nitrogen, and use polyphosphate bacteria to absorb phosphorus; Anoxic I unit, used to provide anoxic environment to facilitate the removal of nitrite nitrogen, nitrate nitrogen and ammonia nitrogen through denitrification and anaerobic ammonium oxidation reactions; Anoxic II unit, used to provide anoxic environment to facilitate the removal of nitrite nitrogen, nitrate nitrogen and ammonia nitrogen through denitrification and anaerobic ammonium oxidation reactions; Aerobic II unit is used to provide an aerobic environment with a dissolved oxygen concentration higher than a preset value to facilitate aerobic phosphorus removal and ammonia nitrogen oxidation reactions; Secondary sedimentation tank unit, used for mud-water separation, with the bottom sludge returned to the anaerobic unit; An outlet tank, used to receive the clarified water separated by the secondary sedimentation tank unit; The first dosing unit is arranged corresponding to the anaerobic unit and is used for adding nano-ferroferric oxide into the anaerobic unit.

2. The low-carbon emission rural sewage treatment system according to claim 1 is characterized in that: Also includes: The second dosing unit is provided corresponding to the anoxic unit I and is used to add nano-iron tetroxide to the anoxic unit I; The third dosing unit is arranged corresponding to the anoxic II unit and is used for adding nano-ferroferric oxide into the anoxic II unit.

3. The rural sewage treatment system with low carbon emission according to claim 1 is characterized by: The anaerobic unit, aerobic I unit, anoxic I unit and aerobic II unit adopt activated sludge reactors; The anoxic II unit adopts a fixed bed biofilm reactor, in which a composite filler is used, the filling rate is 60-80%, and a metal frame is used to fix the reactor.

4. The low-carbon emission rural sewage treatment system according to claim 3 is characterized by: The anaerobic unit, aerobic I unit, anoxic I unit, anoxic II unit and aerobic II unit are inoculated with common activated sludge; The anoxic I unit and the anoxic II unit are inoculated with anaerobic ammonium oxidation sludge.

5. The rural sewage treatment system with low carbon emission according to claim 1 is characterized by: The dissolved oxygen concentration in the aerobic I unit is 0.2-0.5 mg / L; the dissolved oxygen concentration in the aerobic II unit is 4.0-5.0 mg / L.

6. The rural sewage treatment system with low carbon emission according to claim 1 or 2, characterized in that: The dosage of the nano-ferroferric oxide is 3-5 g / L.

7. The rural sewage treatment system with low carbon emission according to claim 1 is characterized by: The pool capacity ratios of the anaerobic unit: aerobic I unit: anoxic I unit: anoxic II unit: aerobic II unit are 1:2:2:2:0.5 respectively.

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