Municipal sewage treatment integration method and system

Abstract

The invention provides a municipal sewage treatment integration method and system. The sewage treatment integration method comprises the following steps: sewage is pretreated and then discharged; a microbial agent is added into the pretreated sewage for a biological reaction, organic matter in the sewage is degraded, and nitrogen and phosphorus are removed; filtering the sewage after the biological reaction is completed, and discharging filtrate; the sludge generated after filtration is subjected to concentration, dehydration and stabilization treatment, and then is subjected to sludge anaerobic digestion for energy recovery. According to the sewage treatment integration method provided by the invention, the sewage treatment efficiency and the water quality standard are greatly improved by adopting a manner of pre-treating the municipal sewage and then adding the microbial agent for biological reaction, and meanwhile, the energy consumption is well reduced, and a relatively good energy recovery effect is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and in particular, relates to an integrated method and system for municipal sewage treatment. Background Art

[0002] Traditional municipal sewage treatment processes have problems such as low treatment efficiency, high energy consumption, and low resource recovery rate. With the acceleration of urbanization, sewage discharge has increased dramatically, which has put forward higher requirements for sewage treatment processes. Therefore, the development of an efficient, environmentally friendly, and energy-saving municipal sewage treatment integrated process has become an urgent problem to be solved.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] The first purpose of the present invention is to provide an integrated method for municipal sewage treatment, which can effectively achieve the treatment of municipal sewage, optimize the process of sewage treatment methods, improve resource recovery and utilization rates, thereby better improving municipal sewage treatment efficiency and water quality discharge standards, and can better reduce energy consumption and energy recovery.

[0005] The second purpose of the present invention is to provide an integrated municipal sewage treatment system, which optimizes the process flow of sewage treatment, integrates multiple modules such as high-efficiency pretreatment and biological reaction, thereby forming a complete, efficient and environmentally friendly sewage treatment system, effectively improving the sewage treatment efficiency.

[0006] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted: An integrated method for municipal sewage treatment comprises the following steps: Pre-treat the sewage before discharging it; Then, microbial agents are added to the pretreated sewage for biological reaction to degrade organic matter in the sewage and remove nitrogen and phosphorus; The wastewater after the biological reaction is completed is filtered and the filtrate is discharged; The sludge produced after filtration is concentrated, dehydrated and stabilized, and then anaerobic digested for energy recovery.

[0007] Preferably, as a further implementable solution, the pretreatment step is: Add flocculant to the pre-treated sewage for flocculation and sedimentation for 10h-15h; The wastewater is then filtered using a multi-layer screen.

[0008] Preferably, as a further implementable solution, the grid is arranged in 3-5 layers; Preferably, the grid is arranged in three layers.

[0009] In the integrated method for municipal sewage treatment of the present invention, the municipal sewage is preliminarily treated mainly by pretreatment, wherein a multi-layer screen is used to remove large particles in the municipal sewage. The multi-layer screen can more effectively intercept larger suspended matter and floating matter in the municipal sewage, and can better prevent these impurities from entering the subsequent treatment equipment, thereby ensuring the normal operation of the sewage treatment. The large particles in the sewage are removed by the multi-layer screen to avoid the large particles in the municipal sewage from affecting the subsequent biological reactions, thereby affecting the removal of nitrogen and phosphorus in the sewage. The multi-layer setting of the screen can be more helpful in improving the effluent quality, because after removing the large particles and suspended matter in the sewage, the subsequent treatment method can focus more on removing finer pollutants, thereby improving the reaction efficiency of the subsequent biological reaction, so that it can accurately remove the small molecules contained in the sewage. Therefore, for the present invention, the number of layers of the grid is very important. This is because when the number of layers of the grid is 3-5 layers, preferably 3 layers, it has excellent initial pretreatment effect on sewage and can better remove large particle impurities and larger suspended matter in sewage. If the number of grid layers is too many, the flow rate of sewage will be smaller when it passes through the grid treatment, thereby affecting the subsequent biological reaction efficiency. If the number of grid layers is too few, most of the suspended matter and large particles in the sewage will clog the grid, thereby affecting the pretreatment effect of the sewage, causing the large particles and suspended matter in the sewage to affect the subsequent treatment effect of the microbial agent on the sewage.

[0010] Preferably, as a further feasible solution, the flocculant is a mixture of polyaluminium chloride and aluminium chloride.

[0011] Preferably, as a further feasible solution, the mass ratio of the polyaluminium chloride to aluminium chloride is (1-2):1.

[0012] Preferably, as a further implementable scheme, the mass ratio of the polyaluminium chloride to aluminium chloride is 1:1.

[0013] In the present invention, a flocculant is prepared by mixing polyaluminium chloride and aluminium chloride, and a better flocculation effect is achieved in this way. This is because after pre-treatment of municipal sewage, there are still suspended matter that has not been completely treated by the grid and some small particles visible to the naked eye in the water. Therefore, it is necessary to add a flocculant in the pre-treatment to precipitate the small particles and suspended matter in the water. The mixture of polyaluminium chloride and aluminium chloride can achieve a better purification effect. This is because polyaluminium chloride can combine with small particles, suspended matter and other negatively charged particles in the water through cations, so that they are condensed into larger coagulants and precipitated at the bottom for filtration, while aluminium chloride can react chemically with impurity particles in the water to generate precipitates that are insoluble in water. In this way, suspended matter and particles in the water can be better removed. Therefore, for the present invention, the dosage ratio between the two is very important. This is because when the mass ratio of polyaluminium chloride to aluminium chloride is (1-2):1, preferably when the mass ratio of polyaluminium chloride to aluminium chloride is 1:1, the flocculant obtained after mixing them has excellent flocculation effect, which can well remove suspended matter and large particles in water. If polyaluminium chloride is excessive, a large amount of alkali in the water will be consumed, thereby reducing the pH value of the water. The subsequent treatment of sewage requires the addition of more alkali for neutralization, which invisibly increases the cost of sewage treatment. The reduction in pH will affect the flocculation effect of aluminium chloride to a certain extent, thereby affecting the removal of suspended matter and large particles in sewage. If the amount of polyaluminium chloride is too small, most of the large particles and suspended matter cannot be fully precipitated in the early stage of sewage pretreatment, thereby affecting the subsequent pretreatment effect.

[0014] Preferably, as a further feasible solution, the microbial agent is a composite biological agent for strong degradation of organic matter.

[0015] Preferably, as a further feasible solution, the dosage of the organic matter strong degradation composite biological bacterial agent is 20-30 mg / L.

[0016] Preferably, as a further feasible solution, the dosage of the organic matter strong degradation composite biological bacterial agent is 25 mg / L.

[0017] In the present invention, the dosage of the microbial agent is very important, because the present invention uses the microbial agent to degrade organic matter and nitrogen and phosphorus contained in sewage, and too little dosage will lead to higher organic matter and nitrogen and phosphorus content in the water.

[0018] The present invention also provides an integrated municipal sewage treatment system, comprising a pretreatment tank, a multi-stage bioreactor, a filtering tank and an energy recovery tank.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides an integrated method for municipal sewage treatment, which can effectively achieve the treatment of municipal sewage. By optimizing the sewage treatment process and improving the resource recovery rate, the municipal sewage treatment efficiency and water quality discharge standards can be better improved, and energy consumption can be better reduced and energy recovery can be achieved.

[0020] (2) The present invention provides an integrated municipal sewage treatment system, which optimizes the sewage treatment process and integrates multiple modules such as high-efficiency pretreatment and biological reaction to form a complete, efficient and environmentally friendly sewage treatment system, thereby effectively improving the sewage treatment efficiency. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be clearly and completely described below in conjunction with specific implementation methods, but those skilled in the art will understand that the embodiments described below are part of the embodiments of the present invention, rather than all of the embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0022] In order to more clearly explain the technical solution of the present invention, it is described in the form of specific embodiments below.

[0023] Example 1 Collecting municipal sewage; Then, the municipal sewage was introduced into the pretreatment tank, and a flocculant prepared by mixing polyaluminium chloride and aluminium chloride in a mass ratio of 1:1 was added into the pretreatment tank for flocculation, followed by sedimentation for 10 hours; After the sedimentation is completed, the water pump provided on the pretreatment tank is turned on, and then the precipitated sewage in the pretreatment tank is introduced into the multi-stage bioreactor through the water outlet provided in the pretreatment tank, wherein three layers of grids are provided in front of the water outlet of the pretreatment tank, and the sewage in the pretreatment tank is filtered through the three layers of grids; Then, 20 mg / L of organic matter strong degradation composite biological agent was added into the multi-stage bioreactor for 10 hours to degrade organic matter contained in the sewage and remove nitrogen and phosphorus contained in the sewage; After the reaction is completed, the sewage is introduced into the filter tank for filtration again. At this time, the filtrate is discharged and the sludge produced by the filtration is introduced into the energy recovery tank; Energy recovery can be achieved by carrying out anaerobic digestion of sludge after concentration, dehydration and stabilization in the energy recovery pool.

[0024] Example 2 Collecting municipal sewage; Then, the municipal sewage was introduced into the pretreatment tank, and a flocculant prepared by mixing polyaluminium chloride and aluminium chloride in a mass ratio of 1:2 was added into the pretreatment tank for flocculation, followed by sedimentation for 15 hours; After the sedimentation is completed, the water pump provided on the pretreatment tank is turned on, and then the precipitated sewage in the pretreatment tank is introduced into the multi-stage bioreactor through the water outlet provided in the pretreatment tank, wherein 5 layers of grids are provided in front of the water outlet of the pretreatment tank, and the sewage in the pretreatment tank is filtered through the 5 layers of grids; Then, 30 mg / L of organic matter strong degradation composite biological agent was added into the multi-stage bioreactor for 10 hours to degrade organic matter contained in the sewage and remove nitrogen and phosphorus contained in the sewage; After the reaction is completed, the sewage is introduced into the filter tank for filtration again. At this time, the filtrate is discharged and the sludge produced by the filtration is introduced into the energy recovery tank; Energy recovery can be achieved by carrying out anaerobic digestion of sludge after concentration, dehydration and stabilization in the energy recovery pool.

[0025] Example 3 Collecting municipal sewage; Then, the municipal sewage was introduced into the pretreatment tank, and a flocculant prepared by mixing polyaluminium chloride and aluminium chloride in a mass ratio of 1:1 was added into the pretreatment tank for flocculation, followed by sedimentation for 15 hours; After the sedimentation is completed, the water pump provided on the pretreatment tank is turned on, and then the precipitated sewage in the pretreatment tank is introduced into the multi-stage bioreactor through the water outlet provided in the pretreatment tank, wherein three layers of grids are provided in front of the water outlet of the pretreatment tank, and the sewage in the pretreatment tank is filtered through the three layers of grids; Then, 25 mg / L of organic matter strong degradation composite biological agent was added into the multi-stage bioreactor for 10 hours to degrade organic matter contained in the sewage and remove nitrogen and phosphorus contained in the sewage; After the reaction is completed, the sewage is introduced into the filter tank for filtration again. At this time, the filtrate is discharged and the sludge produced by the filtration is introduced into the energy recovery tank; Energy recovery can be achieved by carrying out anaerobic digestion of sludge after concentration, dehydration and stabilization in the energy recovery pool.

[0026] Example 4 The specific implementation method is consistent with Example 3, except that polyaluminium chloride and aluminium chloride are mixed in a mass ratio of 1:3 to prepare the flocculant.

[0027] Example 5 The specific implementation method is consistent with Example 3, except that polyaluminium chloride and aluminium chloride are mixed in a mass ratio of 3:1 to prepare the flocculant.

[0028] Example 6 The specific implementation is consistent with Example 3, except that the number of grid layers is set to 1.

[0029] Example 7 The specific implementation is consistent with Example 3, except that the number of grid layers is set to 8.

[0030] Example 8 The specific implementation method is consistent with Example 3, except that the dosage of the organic matter strong degradation composite biological bacterial agent is adjusted to 5 mg / L.

[0031] Example 9 The specific implementation method is consistent with Example 3, except that the dosage of the organic matter strong degradation composite biological bacterial agent is adjusted to 50 mg / L.

[0032] Comparative Example 1 The specific implementation method is consistent with Example 3, except that the organic matter strong degradation composite biological agent is replaced by denitrifying bacteria.

[0033] Comparative Example 2 The specific implementation method is consistent with Example 3, except that the flocculant is replaced by aluminum sulfate.

[0034] The filtrates obtained in Examples 1-9 and Comparative Examples 1-2 were used for water quality testing, and the final results are shown in Table 1 below.

[0035]

[0036] It can be seen from the above experimental data that, compared with Examples 3-4 and Comparative Example 2, the dosage ratio of the flocculants is very important for the present invention. This is because in the present invention, the flocculant is mainly prepared by mixing polyaluminium chloride and aluminium chloride, and a better flocculation effect is achieved in this way. This is because after the municipal sewage is pretreated, there are still suspended matter that has not been completely treated by the grid and a part of small particulate matter visible to the naked eye in the water. Therefore, it is necessary to add a flocculant in the pretreatment to precipitate the small particles and suspended matter in the water. Among them, the mixture of polyaluminium chloride and aluminium chloride can achieve a better purification effect. This is because polyaluminium chloride can combine with small particles, suspended matter and other negatively charged particles in the water through cations, so that they are condensed into larger coagulants and precipitated at the bottom for filtration, while aluminium chloride can react chemically with impurity particles in the water to generate water-insoluble Precipitate, in this way, the suspended matter and particulate matter in the water can be better removed. Therefore, for the present invention, the dosage ratio between the two is very important. This is because when the mass ratio of polyaluminium chloride and aluminium chloride is (1-2):1, preferably when the mass ratio of polyaluminium chloride and aluminium chloride is 1:1, the flocculant obtained after mixing has excellent flocculation effect, which can well remove suspended matter and large particulate matter in the water. If polyaluminium chloride is excessive, a large amount of alkali in the water will be consumed, thereby reducing the pH value of the water. The subsequent treatment of the sewage requires the addition of more alkali for neutralization, which invisibly increases the cost of sewage treatment. The reduction in pH will affect the flocculation effect of aluminium chloride to a certain extent, thereby affecting the removal of suspended matter and large particulate matter in the sewage. If the amount of polyaluminium chloride is too small, most of the large particulate matter and suspended matter cannot be fully precipitated in the early stage of sewage pretreatment, thereby affecting the subsequent pretreatment effect.

[0037] By comparing Example 3 and Examples 6-7, it can be seen that the number of layers of the grid is also very important for the present invention. This is because in the integrated method for municipal sewage treatment of the present invention, the municipal sewage is preliminarily treated mainly by pretreatment, wherein a multi-layer grid is used to remove large particles in the municipal sewage. The multi-layer grid can more effectively intercept larger suspended matter and floating matter in the municipal sewage, and can better prevent these impurities from entering the subsequent treatment equipment, thereby ensuring the normal operation of the sewage treatment. The large particle impurities in the sewage are removed by the multi-layer grid, so as to avoid the large particle impurities contained in the municipal sewage from affecting the subsequent biological reaction, thereby affecting the removal of nitrogen and phosphorus in the sewage. The multi-layer setting of the grid can be more helpful in improving the effluent quality, because after removing the large particle impurities and large suspended matter contained in the sewage, the subsequent treatment method can focus more on removing finer pollutants, thereby improving the reaction efficiency of the subsequent biological reaction, so that it can accurately remove the small molecules contained in the sewage. Therefore, for the present invention, the number of layers of the grid is very important. This is because when the number of layers of the grid is 3-5 layers, preferably 3 layers, it has excellent initial pretreatment effect on sewage and can better remove large particle impurities and larger suspended matter in sewage. If the number of grid layers is too many, the flow rate of sewage will be smaller when it passes through the grid treatment, thereby affecting the subsequent biological reaction efficiency. If the number of grid layers is too few, most of the suspended matter and large particles in the sewage will clog the grid, thereby affecting the pretreatment effect of the sewage, causing the large particles and suspended matter in the sewage to affect the subsequent treatment effect of the microbial agent on the sewage.

[0038] By comparing Example 3 with Examples 8-9 and Comparative Example 1, it can be seen that the use of microbial agents is very important for the present invention. This is because the present invention uses microbial agents to degrade organic matter and nitrogen and phosphorus contained in sewage. Too little use will lead to higher organic matter and nitrogen and phosphorus content in the water.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An integrated method for municipal sewage treatment, characterized in that: The following steps are involved: Pre-treat the sewage before discharging it; Then, microbial agents are added to the pretreated sewage for biological reaction to degrade organic matter in the sewage and remove nitrogen and phosphorus; The wastewater after the biological reaction is completed is filtered and the filtrate is discharged; The sludge produced after filtration is concentrated, dehydrated and stabilized, and then anaerobic digested for energy recovery.

2. The integrated method for municipal sewage treatment according to claim 1, characterized in that: The pre-processing steps are: Add flocculant to the pre-treated sewage for flocculation and sedimentation for 10h-15h; The wastewater is then filtered using a multi-layer screen.

3. The integrated method for municipal sewage treatment according to claim 2, characterized in that: The grid is set to 3-5 layers; Preferably, the grid is arranged in three layers.

4. The integrated method for municipal sewage treatment according to claim 2, characterized in that: The flocculant is a mixture of polyaluminium chloride and aluminium chloride.

5. The integrated method for municipal sewage treatment according to claim 4, characterized in that: The mass ratio of the polyaluminium chloride to aluminium chloride is (1-2):

1.

6. The integrated method for municipal sewage treatment according to claim 5, characterized in that: The mass ratio of the polyaluminium chloride to aluminium chloride is 1:

1.

7. The integrated method for municipal sewage treatment according to claim 1, characterized in that: The microbial agent is a composite biological agent that can strongly degrade organic matter.

8. The integrated method for municipal sewage treatment according to claim 7, characterized in that: The dosage of the organic matter strong degradation composite biological bacterial agent is 20-30 mg / L.

9. The integrated method for municipal sewage treatment according to claim 8, characterized in that: The dosage of the organic matter strong degradation composite biological bacterial agent is 25 mg / L.

10. An integrated municipal sewage treatment system according to any one of claims 1 to 9, characterized in that: It includes pretreatment tank, multi-stage bioreactor, filtration tank and energy recovery tank.

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