Regulation and control system for quickly realizing high-standard discharge of wastewater with different C / N ratios

Abstract

The invention discloses a regulation and control system for rapidly realizing high-standard discharge of wastewater with different C / N ratios, the regulation and control system comprises a pretreatment unit, a biological treatment unit and an advanced treatment unit which are connected in sequence, the pretreatment unit is connected with a first dosing unit, the biological treatment unit is connected with an inflow water distribution unit and a multi-parameter automatic control unit, and the advanced treatment unit is connected with a second dosing unit. The deep treatment unit is connected with a second dosing unit; or the pretreatment unit is connected with an acid-base adjusting unit, the biological treatment unit is connected with an inflow water distribution unit, a multi-parameter automatic control unit and a carbon source adding unit, and the deep treatment unit is connected with a second dosing unit. The problems that high C / N ratio sewage causes excessive reproduction of heterotrophic bacteria and low C / N ratio wastewater needs a large number of additional carbon sources are solved, energy consumption and the additional carbon sources are saved, the operation cost is reduced, and efficient nitrogen removal of a biological treatment unit is achieved; and the sludge load can be effectively reduced, the effluent quality is ensured to meet the requirement of high emission standard, and the application range is wide.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and particularly relates to a regulation system for quickly achieving high-standard discharge of wastewater with different C / N ratios. Background Art

[0002] In recent years, with the increasingly strict national sewage discharge supervision, each region has raised the effluent to the "quasi-Class IV" standard on the basis of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB 18918-2002), putting forward more stringent requirements for the discharge standards of nitrogen and phosphorus. With the development of chemical phosphorus removal technology, total phosphorus is no longer a factor restricting the effluent to meet the standard. The key to ensuring the effluent to meet the standard is to achieve stable compliance of total nitrogen. Therefore, exploring an economical and efficient denitrification process has become a hot topic in current sewage treatment research. Municipal sewage in various regions of our country shows obvious differences in C / N ratio. Both too high or too low influent carbon source will limit the up-to-standard discharge of total nitrogen.

[0003] Compared with treatment processes such as anaerobic / anoxic / aerobic process (AAO) and sequencing batch reactor (SBR), the multi-stage anoxic-aerobic (multi-stage AO) process has the characteristics of high carbon source utilization rate and strong sewage denitrification ability, and is the preferred process for upgrading sewage treatment plants. The multi-stage AO process is composed of 2-5 stages of anoxic and aerobic tanks in series. The nitrified liquid directly flows from the aerobic zone of each section into the anoxic zone of the next section without setting up an internal reflux system. The sewage passes through the multi-stage alternating anoxic and aerobic zones to achieve efficient denitrification, with advantages such as small required tank volume, high denitrification efficiency, and flexible operation adjustment. pH value, dissolved oxygen (DO), sludge age, hydraulic retention time (HRT), influent flow distribution mode, and nitrified liquid reflux ratio are the main factors affecting the denitrification performance of the multi-stage AO process, which determine the effluent quality of the multi-stage AO process. Among them, segmented influent is a typical advantage of the multi-stage AO process, which can fully tap the utilization potential of the internal carbon source in sewage, avoid the problem of nitrifying bacteria inhibition caused by high organic matter concentration, and at the same time can provide sufficient carbon source for denitrifying bacteria, thereby improving the overall denitrification efficiency. Different influent ratios change the distribution of carbon source in the multi-stage AO system, thus affecting the denitrification and phosphorus removal effects. By adjusting the influent flow distribution mode, the organic matter load and nitrogen load in the reaction tank can be reasonably distributed, and at the same time, the contradiction between oxygen supply and oxygen demand in the traditional plug-flow aeration tank is alleviated, which can effectively reduce the dosage of externally added carbon source and achieve economical and efficient denitrification. The nitrified liquid reflux ratio determines the total nitrogen concentration of the effluent of the multi-stage AO process, and its denitrification effect is proportional to the nitrified liquid reflux ratio within a certain range. When the carbon source is sufficient, too low nitrified liquid reflux ratio weakens the denitrification effect of the anoxic tank, and too much will affect the anoxic environment and inhibit the denitrification effect. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a control system for rapidly achieving high-standard discharge of wastewater with different C / N ratios, so as to solve the deficiencies in the prior art.

[0005] To achieve the above object, the present invention is realized through the following technical solutions:

[0006] Provide a control system for rapidly achieving high-standard discharge of wastewater with different C / N ratios, which includes a pretreatment unit, a biological treatment unit, and a deep treatment unit connected in sequence, wherein:

[0007] The pretreatment unit is connected to a first chemical dosing unit, the biological treatment unit is connected to a water inlet distribution unit and a multi-parameter automatic control unit, and the deep treatment unit is connected to a second chemical dosing unit;

[0008] Or:

[0009] The pretreatment unit is connected to an acid-base adjustment unit, the biological treatment unit is connected to a water inlet distribution unit, a multi-parameter automatic control unit, and a carbon source dosing unit, and the deep treatment unit is connected to a second chemical dosing unit.

[0010] As the control system for rapidly achieving high-standard discharge of wastewater with different C / N ratios, wherein the pretreatment unit is composed of one or more combinations of an oil separation tank, a coagulation tank, a flotation tank, and an adjustment tank.

[0011] As the control system for rapidly achieving high-standard discharge of wastewater with different C / N ratios, wherein the chemicals dosed by the first chemical dosing unit include one or more of polyaluminum chloride, polyferric sulfate, polyaluminum ferric sulfate, polyacrylamide, sodium hydroxide, and hydrochloric acid.

[0012] As the control system for rapidly achieving high-standard discharge of wastewater with different C / N ratios, wherein the biological treatment unit includes an anaerobic tank, a first anoxic zone, a first aerobic zone, a second anoxic zone, a second aerobic zone, a third anoxic zone, and a third aerobic zone connected in sequence.

[0013] As the control system for rapidly achieving high-standard discharge of wastewater with different C / N ratios, wherein the third aerobic zone adopts an aerobic tank in combination with one or a combination of processes of a secondary sedimentation tank, an aerated biological filter, and a membrane bioreactor.

[0014] As the control system for rapidly achieving high-standard discharge of wastewater with different C / N ratios, wherein the activated sludge inoculated in the biological treatment unit can be one or more of aerobic sludge from urban sewage treatment plants, granular sludge, surplus sludge, and dewatered sludge without chemical treatment.

[0015] For the regulation system for quickly achieving high-standard discharge of wastewater with different C / N ratios, wherein the control indicators of the multi-parameter automatic control unit include DO, pH value, excess sludge discharge amount, sludge return ratio, nitrified liquid return ratio, and influent distribution ratio.

[0016] For the regulation system for quickly achieving high-standard discharge of wastewater with different C / N ratios, wherein the carbon source used in the carbon source dosing unit is one or a combination of carbon sources such as glucose, sodium acetate, fatty acid, natural cellulose, and ProCarbon.

[0017] For the regulation system for quickly achieving high-standard discharge of wastewater with different C / N ratios, wherein the advanced treatment unit is one or a combined process of a coagulation sedimentation reactor, a high-efficiency magnetic coagulation reactor, a denitrifying deep bed filter, and other advanced treatment reactors.

[0018] For the regulation system for quickly achieving high-standard discharge of wastewater with different C / N ratios, wherein the coagulation agent dosed in the second chemical dosing unit is one or more of polyaluminum sulfate, polyferric sulfate, calcium oxide, and calcium hydroxide.

[0019] The beneficial effects of the technical solution of the present invention are:

[0020] 1. Preferred distribution mode: This method optimizes the distribution mode according to the influent C / N ratio and adopts a hierarchical nitrification / denitrification method, solving the problems of excessive reproduction of heterotrophic bacteria caused by high C / N ratio sewage and the need for a large amount of externally added carbon source for low C / N ratio wastewater, saving energy consumption and externally added carbon source, reducing the operating cost, and achieving efficient nitrogen removal in the biological treatment unit.

[0021] 2. Quickly achieve stable compliance discharge: By adjusting the internal reflux ratio and the distribution mode of each anoxic tank, the biological treatment unit can adapt to sewage with large fluctuations in water quality and quantity in a short time. With a plug-flow operation mode, it ensures that the abundances of functional microorganisms in each treatment unit are similar. By optimizing the influent distribution ratio, an environment with a high sludge concentration and a low substrate concentration is formed in the latter stage of the process, which can effectively reduce the sludge load and ensure that the effluent quality meets the requirements of high discharge standards.

[0022] 3. Wide application range: The process involved in this system can be flexibly adjusted according to the actual characteristics of sewage water quality, and can adapt to high C / N ratio wastewater such as printing and dyeing wastewater, and can also adapt to low C / N ratio wastewater such as chemical industrial wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] To further illustrate the above objects, structural features, and effects of the present invention, the present invention will be described in detail below with reference to the drawings.

[0024] Figure 1 It is a schematic structural diagram of a preferred embodiment of the present invention;

[0025] Figure 2 Schematic diagram of another preferred embodiment of the present invention;

[0026] In the figure: 1, pretreatment unit; 2, advanced treatment unit; 3, sewage inlet pump; 4, first chemical dosing unit; 5, influent distribution unit; 6, second chemical dosing unit; 7, acid-base adjustment unit; 8, carbon source dosing unit; 9, anaerobic tank; 10, first anoxic zone; 11, first aerobic zone; 12, second anoxic zone; 13, second aerobic zone; 14, third anoxic zone; 15, third aerobic zone; 16, blower; 17, secondary sedimentation tank; 18, agitator; 19, multi-parameter detector; 20, nitrification liquid reflux controller. Detailed implementation manners

[0027] The terms "invention" and "the present invention" as used in this specification are intended generally to refer to all subject matter of this specification and any of the following patent claims. Statements containing these terms should not be construed as limiting the subject matter described herein or the meaning or scope of any of the following patent claims. In addition, this specification does not attempt to describe or limit the subject matter covered by any particular component, paragraph, statement, or claim of this application. The subject matter should be understood with reference to the entire specification, all the drawings, and any of the following claims. The present invention may have other embodiments and be practiced or implemented in other ways. Moreover, it should be understood that the language and terms used herein are for the purpose of description and should not be considered limiting.

[0028] Details of the present invention will now be discussed with reference to the drawings of the present invention, which are provided by way of example only. In the drawings, like features or components may be labeled with the same reference numerals.

[0029] The use of the terms "comprising", "having", and "including" and their variants herein means including the items listed hereinafter, their equivalents, and additional items. Although directions such as above, below, upward, downward, backward, bottom, top, front, and back may be referred to in the description of the drawings for convenience with reference to the drawings, these directions are not intended to be literally accepted or limit the present invention in any form. In addition, terms such as "first", "second", "third", etc. are used herein for the purpose of description and are not intended to indicate or imply importance or significance.

[0030] Referring to Figure 1 As shown, the technical object of the present invention is to provide a control system for quickly achieving high-standard discharge of wastewater with a high C / N ratio. In a preferred embodiment, the system includes a pretreatment unit 1, a biological treatment unit, and an advanced treatment unit 2 connected in sequence. Sewage is introduced into the pretreatment unit 1 through a sewage inlet pump 3. The pretreatment unit 1 is connected to a first chemical dosing unit 4. The biological treatment unit is connected to an influent distribution unit 5 and a multi-parameter automatic control unit. The advanced treatment unit 2 is connected to a second chemical dosing unit 6.

[0031] See Figure 2 As shown, in another preferred embodiment, the pretreatment unit 1 is connected to an acid-base adjustment unit 7, the biological treatment unit is connected to a water inlet distribution unit 5, a multi-parameter automatic control unit, and a carbon source dosing unit 8, and the advanced treatment unit 2 is connected to a second chemical dosing unit 6.

[0032] The pretreatment unit 1 can be composed of one or a combination of an oil separation tank, a coagulation tank, a flotation tank, and an adjustment tank, with a hydraulic retention time of 0.1 - 24 h. Preferably, the chemicals dosed by the first chemical dosing unit 4 connected to the pretreatment unit 1 include one or more of polyaluminum chloride, polyferric sulfate, polyaluminum ferric sulfate, polyacrylamide, sodium hydroxide, and hydrochloric acid. The acid-base adjustment unit 7 connected to the pretreatment unit 1 adjusts the pH value of the pretreatment unit by dosing one of sodium hydroxide or hydrochloric acid.

[0033] The biological treatment unit includes an anaerobic tank 9, a first-stage anoxic zone 10 (first-stage anoxic reactor), a first-stage aerobic zone 11 (first-stage aerobic reactor), a second-stage anoxic zone 12 (second-stage anoxic reactor), a second-stage aerobic zone 13 (second-stage aerobic reactor), a third-stage anoxic zone 14 (third-stage anoxic reactor), and a third-stage aerobic zone 15 (third-stage aerobic reactor) that are connected in sequence. The first-stage aerobic zone 11, the second-stage aerobic zone 13, and the third-stage aerobic zone 15 are respectively connected to a blower 16. The third-stage aerobic zone 15 can be one or a combined process of an aerobic tank + a secondary sedimentation tank 17, an aerated biological filter, and a membrane-biological reactor. Preferably, in terms of the water inlet mode, the water inlet distribution ratio of the anaerobic tank 9 is 0 - 100%. In one technical solution, the end of the anaerobic tank 9 is segmented and fed into three anoxic tanks. In another technical solution, the water inlet is directly distributed to the anaerobic tank 9 and the three anoxic tanks. The HRT of the biological treatment unit is preferably 0.5 - 72 h.

[0034] Mixers 18 are provided in the pretreatment unit 1, the anaerobic tank 9, the first-stage anoxic zone 10, the second-stage anoxic zone 12, the third-stage anoxic zone 14, and the advanced treatment unit 2.

[0035] The activated sludge inoculated in the biological treatment unit can be one or more of aerobic sludge, granular sludge, excess sludge, and undosed dewatered sludge from a municipal sewage treatment plant.

[0036] The biological treatment unit is equipped with multi-parameter water quality monitoring instruments. Preferably, the water quality monitoring indicators include DO, pH value, sludge mixed liquor concentration, and temperature. The control indicators of the multi-parameter automatic control unit connected to the biological treatment unit include DO, pH value (multi-parameter detector 19), excess sludge discharge amount, sludge return ratio, nitrification liquid return ratio (nitrification liquid return controller 20), and influent distribution ratio. The carbon source used in the carbon source dosing unit 8 connected to the biological treatment unit is one or a combination of glucose, sodium acetate, fatty acid, natural cellulose, and Procarbon.

[0037] The advanced treatment unit 2 can be a coagulation sedimentation reactor, a high-efficiency magnetic coagulation reactor, a denitrification deep bed filter, or a combined process of other advanced treatment reactors. Preferably, the HRT of the advanced treatment unit 2 is 0.5 - 24h. The coagulation agents dosed in the second dosing unit 6 connected to the advanced treatment unit 2 are one or more of polyaluminum sulfate, polyferric sulfate, calcium oxide, and calcium hydroxide.

[0038] The sewage treated by the present invention can be high C / N ratio wastewater or low C / N ratio wastewater. The former includes but is not limited to printing and dyeing wastewater, pharmaceutical wastewater, food wastewater, and paper-making wastewater, and the latter includes but is not limited to municipal sewage, metallurgical wastewater, and chemical industrial wastewater.

[0039] The present invention also relates to a control system for automatically adjusting the internal reflux ratio and influent distribution ratio according to the influent water quality and C / N ratio, which is applied to the three-stage AO treatment system described above.

[0040] The principle of the present invention is as follows: Based on the basic principle of biological denitrification of anoxic-aerobic in traditional theory, a multi-stage AO series connection method is adopted to improve the total nitrogen removal rate. However, simply connecting multi-stage A / O processes in series cannot ensure the rapid and stable compliance of the process. High C / N ratio sewage usually contains a large amount of refractory organic matter, and an anaerobic tank needs to be added to hydrolyze macromolecular organic matter into small molecular organic matter that can be easily utilized by denitrifying bacteria. At the same time, a large amount of organic matter enters the first-stage aerobic unit, resulting in the rapid growth of heterotrophic bacteria with a short generation time. The high abundance of heterotrophic bacteria competes with nitrifying bacteria for dissolved oxygen and occupies the ecological niche of nitrifying bacteria, thus affecting the overall nitrification ability of the system and further affecting the total nitrogen removal rate. Therefore, the effluent of the anaerobic tank is distributed to three anoxic units in a preferred distribution mode at the end of the anaerobic tank to reduce the influent organic matter in the aerobic unit and inhibit the growth of heterotrophic bacteria.

[0041] Low C / N ratio sewage may also contain a large amount of difficult-to-degrade organic matter and still need to be treated in an anaerobic tank. However, if the insufficient influent carbon source is removed in large quantities in the anaerobic tank, the subsequent anoxic unit will not be able to operate at all due to lack of carbon source, which will lead to further deterioration of effluent quality. More external carbon sources are required to provide sufficient electron donors for denitrifying bacteria, resulting in increased treatment costs. Therefore, the preferred distribution mode is adopted for low C / N ratio sewage. According to the actual influent water quality characteristics, the influent is diverted to the anaerobic unit and each anoxic unit according to the preferred distribution ratio, which can effectively reduce the amount of external carbon source. In addition, the raw water is distributed in stages, and the dissolved oxygen concentration of the aerobic tank can be adjusted step by step, further saving operating costs. Specific embodiment:

[0043] The water quality and quantity of the wastewater in a food factory industrial park vary greatly, with high concentrations of organic matter and ammonia nitrogen. The influent ammonia nitrogen concentration is 115.3±45.5mg / L, and the COD / TN is in the range of 8.8-12.6, which is a high C / N ratio wastewater. The effluent water quality index adopts the "quasi-IV class" standard, that is, the effluent COD, ammonia nitrogen, total phosphorus and other indicators implement the "Surface Water Environmental Quality Standard" (GB3838-2002) Class IV standard, the effluent TN ≤ 10.0mg / L, and the other indicators implement the "Urban Wastewater Treatment Plant Pollutant Discharge Standard" (GB18918-2002) Class A standard. In order to ensure that the effluent water quality indicators meet the discharge requirements, the industrial park wastewater is treated through the coordinated optimization of physical and chemical pretreatment, biochemical treatment and deep treatment units in view of the complex water quality characteristics of the industrial park sewage.

[0044] The sewage in the park adopts the treatment process of pretreatment unit + biological reaction unit + deep treatment unit. The pretreatment unit is composed of fine screen, oil separator, regulating tank, fine screen and flotation tank. The biological reaction unit is composed of three-stage AO system. The deep treatment unit is composed of magnetic coagulation high-efficiency sedimentation tank, denitrification filter and disinfection unit. The effluent of the flotation tank enters the biological reaction tank, which uses anaerobic + 3-stage AO to remove most of the organic matter, ammonia nitrogen and total nitrogen in the sewage. There is a total of 1 biological reaction tank, 2 groups in each tank, and the total designed flow rate is 35,000m 3 / d, Kz = 1.2, hydraulic retention time is 58h, of which the retention time of anaerobic tank is 10h, the retention time of each anoxic tank is 4h, the retention time of each aerobic tank is 12h, the designed sludge concentration is 4g / L, and the designed sludge age is 20d. The water inlet method is 100% water inlet to the anaerobic tank, the end of the anaerobic tank is segmented to the 3 anoxic tanks, the internal reflow is from aerobic tank 3 to anoxic tank 1, and the external reflow is from the secondary sedimentation tank to the anaerobic tank. The effluent of the biological reaction unit enters the central inlet and peripheral outlet radial flow secondary sedimentation tank for mud and water separation. At the same time, the sludge at the bottom of the secondary sedimentation tank is concentrated and returned to the anaerobic tank to supplement the sludge concentration. The effluent of the secondary sedimentation tank enters the deep treatment unit for subsequent treatment.

[0045] After 40 days of commissioning operation, the effluent COD, ammonia nitrogen, total nitrogen, total phosphorus and SS of the industrial park are 26.4±6.6, 0.7±0.2, 4.5±0.8, 0.03±0.07 and 0.05±0.01 mg / L respectively, all of which can meet the requirements of the "quasi-Class IV" discharge standard.

[0046] The above are only the preferred embodiments of the present invention, and do not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be realized that all the equivalent replacements and obvious changes made by using the description and illustration content of the present invention should be included in the protection scope of the present invention.

Claims

1. A regulation system for quickly achieving high-standard discharge of wastewater with different C / N ratios, characterized in that It includes a pretreatment unit, a biological treatment unit, and an advanced treatment unit connected in sequence, where: The pretreatment unit is connected to a first chemical dosing unit, the biological treatment unit is connected to a water inlet distribution unit and a multi-parameter automatic control unit, and the advanced treatment unit is connected to a second chemical dosing unit; Or: The pretreatment unit is connected to an acid-base adjustment unit, the biological treatment unit is connected to a water inlet distribution unit, a multi-parameter automatic control unit, and a carbon source dosing unit, and the advanced treatment unit is connected to a second chemical dosing unit.

2. The regulation system for quickly achieving high-standard discharge of wastewater with different C / N ratios as described in claim 1, wherein The pretreatment unit is composed of one or more combinations of an oil separation tank, a coagulation tank, a flotation tank, and an adjustment tank.

3. The regulation system for quickly achieving high-standard discharge of wastewater with different C / N ratios according to claim 2, characterized in that, The chemicals dosed by the first chemical dosing unit include one or more of polyaluminum chloride, polyferric sulfate, polyaluminum ferric sulfate, polyacrylamide, sodium hydroxide, and hydrochloric acid.

4. The regulation system for quickly achieving high-standard discharge of wastewater with different C / N ratios as described in claim 1, characterized in that, The biological treatment unit includes an anaerobic tank, a first anoxic zone, a first aerobic zone, a second anoxic zone, a second aerobic zone, a third anoxic zone, and a third aerobic zone connected in sequence.

5. The regulation system for quickly achieving high-standard discharge of wastewater with different C / N ratios as described in claim 4, characterized in that, The third aerobic zone adopts an aerobic tank in combination with one or a combination of processes of a secondary sedimentation tank, an aerated biological filter, and a membrane bioreactor.

6. The regulation system for rapidly achieving high-standard discharge of wastewater with different C / N ratios as described in claim 4, characterized in that, The activated sludge inoculated in the biological treatment unit can be one or more of aerobic sludge, granular sludge, excess sludge, and dewatered sludge without chemical treatment from urban sewage treatment plants.

7. The regulation system for rapidly achieving high-standard discharge of wastewater with different C / N ratios as described in claim 1, characterized in that The control indicators of the multi-parameter automatic control unit include DO, pH value, excess sludge discharge amount, sludge return ratio, nitrified liquid return ratio, and water inlet distribution ratio.

8. The regulation system for rapidly achieving high-standard discharge of wastewater with different C / N ratios according to claim 1, characterized in that, The carbon source used by the carbon source dosing unit is one or a combination of carbon sources such as glucose, sodium acetate, fatty acids, natural cellulose, and Procarbon.

9. The regulation system for rapidly achieving high-standard discharge of wastewater with different C / N ratios as claimed in claim 1, characterized in that, The advanced treatment unit is one or a combination of processes of a coagulation sedimentation reactor, a high-efficiency magnetic coagulation reactor, a denitrification deep bed filter, and other advanced treatment reactors.

10. The regulation system for rapidly achieving high-standard discharge of wastewater with different C / N ratios according to claim 9, characterized in that, The coagulation chemicals dosed by the second chemical dosing unit are one or more of polyaluminum sulfate, polyferric sulfate, calcium oxide, and calcium hydroxide.

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