CN111661983A - Municipal wastewater treatment method and system - Google Patents
Municipal wastewater treatment method and system Download PDFInfo
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- CN111661983A CN111661983A CN202010546054.3A CN202010546054A CN111661983A CN 111661983 A CN111661983 A CN 111661983A CN 202010546054 A CN202010546054 A CN 202010546054A CN 111661983 A CN111661983 A CN 111661983A
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- C02F9/00—Multistage treatment of water, waste water or sewage
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- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
- C02F1/5245—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents using basic salts, e.g. of aluminium and iron
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- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
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- C02F2203/00—Apparatus and plants for the biological treatment of water, waste water or sewage
- C02F2203/006—Apparatus and plants for the biological treatment of water, waste water or sewage details of construction, e.g. specially adapted seals, modules, connections
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- C02F2209/08—Chemical Oxygen Demand [COD]; Biological Oxygen Demand [BOD]
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- C02F2209/11—Turbidity
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- C02F2209/16—Total nitrogen (tkN-N)
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Abstract
The invention relates to a municipal wastewater treatment method and system, and belongs to the technical field of water treatment. The method comprises the following steps: step 1, pre-filtering municipal wastewater, and then carrying out anaerobic decomposition treatment on filtrate; step 2, carrying out contact oxidation treatment on the wastewater subjected to anaerobic decomposition in the step 1; step 3, filtering sludge from the wastewater after the contact oxidation treatment; step 4, performing aerobic decomposition treatment on the filtrate obtained in the step 3 by adopting an MBR (membrane bioreactor); and 5, adsorbing and removing phosphorus from the wastewater obtained in the 4 step by using a phosphorus adsorption packed tower. The treatment process solves the problems of poor coagulation effect in municipal wastewater treatment and influence on operation of sludge in the MBR reaction process in the prior art.
Description
Technical Field
The invention relates to a municipal wastewater treatment method and system, and belongs to the technical field of water treatment.
Background
Municipal sewage treatment and reuse water are essential energy for people's life, and in modern cities, the problem of water resource shortage is very prominent, how to effectively alleviate the water resource shortage situation, is the key content that needs attention in city development. In urban production and life, a large amount of sewage can be generated, the treatment and recycling utilization level of the sewage is improved, and the method plays an important role in urban water environment protection and water system virtuous cycle. At the present stage of the practical significance of municipal sewage treatment and recycling, the discharge amount of municipal sewage is large, and most of the municipal sewage is concentrated in sewage treatment plants. The treatment and the recycling of the municipal sewage have certain practical significance. Firstly, municipal sewage is treated and recycled, so that the condition of shortage of urban water resources can be relieved, the waste of fresh water resources is avoided, and the sustainable utilization level of the water resources is improved; secondly, the municipal sewage treatment and recycling can reduce the actual discharge amount of sewage and prevent the pollution of the water resource caused by the discharge of the sewage; meanwhile, the cost is saved in the aspect of treating water pollution.
In the prior art, the municipal wastewater treatment process usually adopts chemical methods (coagulation, flocculation), biochemical methods (anaerobic, aerobic) and other steps, and the treatment process usually has the problem of poor system integration.
Disclosure of Invention
The invention provides a municipal wastewater treatment process integrating a coagulation method and a biochemical method, which mainly comprises the following improvement points:
firstly, a reinforced coagulation means is introduced in the coagulation process, so that the coagulation treatment effect on municipal wastewater is improved, and the removal rate of COD, total nitrogen and total phosphorus is obviously improved. The reinforced coagulation is assisted by adding a cationic polymer, and the coagulant is magnetized by a magnetic field, so that the influence of an electric double layer on the surface of the concrete on the coagulation effect in the coagulation process is overcome.
Secondly, in order to solve the problem of overlarge load of the MBR in the prior art, the COD in the wastewater is reduced by adopting the contact oxidation as the pretreatment step of the MBR, so that the MBR runs more stably.
Thirdly, the sludge formed in the contact oxidation process is filtered, so that the problem of operation flux attenuation caused by introducing excessive sludge into the MBR is avoided.
Fourthly, through in the filtering process to mud, introduce negative pressure self-interacting module, according to the degree of compaction of dull and stereotyped ceramic membrane's surface formation mud, suction and the anti-atmospheric pressure of self-regulating ground control negative pressure blast, have avoided the more compact problem of mud.
A municipal wastewater treatment method comprises the following steps:
step 1, pre-filtering municipal wastewater, and then carrying out anaerobic decomposition treatment on filtrate;
step 2, carrying out contact oxidation treatment on the wastewater subjected to anaerobic decomposition in the step 1;
step 3, filtering sludge from the wastewater after the contact oxidation treatment;
step 4, performing aerobic decomposition treatment on the filtrate obtained in the step 3 by adopting an MBR (membrane bioreactor);
and 5, adsorbing and removing phosphorus from the wastewater obtained in the 4 step by using a phosphorus adsorption packed tower.
In one embodiment, before the 1 st step of sand filtration, coagulation treatment is also required on the wastewater.
In one embodiment, a coagulant is added in the coagulation treatment, and the coagulant is selected from polyaluminium chloride, ferric chloride, aluminum ferric sulfate and the like.
In one embodiment, the coagulant is added to the wastewater in an amount of about 50 to 200 ppm.
In one embodiment, in the coagulation treatment, a reinforced coagulant is also required to be added, wherein the reinforced coagulant is a cationic organic polymeric flocculant; the cationic organic polymer is selected from poly dimethyl diallyl ammonium chloride.
In one embodiment, the adding amount of the enhanced coagulant in the wastewater is controlled to be about 30-90 mg/L.
In one embodiment, the coagulant is magnetized by a magnetic field before being added into the wastewater, the magnetic field intensity can be controlled to be 5-30mT, and the action time of the magnetic field can be controlled to be 5-20 min.
In one embodiment, the hydraulic retention time of the anaerobic treatment process in step 1 is controlled to be more than 24 hours, and the dissolved oxygen concentration is less than 0.5 mg/L.
In one embodiment, in step 2, the reactor of the contact oxidation treatment is filled with filler, the bottom of the reactor is aerated, the hydraulic retention time can be controlled to be 24-72h, and the dissolved oxygen can be controlled to be 1.5-2.5 mg/L.
In one embodiment, in step 3, the waste water after the contact oxidation treatment is filtered by using a flat ceramic membrane, wherein a penetrating fluid channel is formed inside the flat ceramic membrane, and the penetrating fluid is pumped to the flat ceramic membrane by connecting to a negative pressure pump.
In one embodiment, in the 4 th step, the bottom of the MBR is aerated to make the content of dissolved oxygen 2-4mg/L, the MLSS of the wastewater can be controlled at about 5000-.
A municipal wastewater treatment system comprising:
the sand filter is used for filtering the wastewater;
the anaerobic reactor is connected with the sand filter and is used for carrying out anaerobic decomposition treatment on the filtrate obtained in the sand filter;
the contact oxidation tank is connected with the anaerobic reactor and is used for carrying out contact oxidation treatment on the wastewater obtained in the anaerobic reactor; a suspension filler is arranged in the contact oxidation pond;
the flat ceramic membrane is connected with the contact oxidation tank and is used for filtering the wastewater obtained in the contact oxidation tank to remove sludge;
the hollow fiber membrane MBR reactor is connected to the permeation side of the flat ceramic membrane and is used for carrying out MBR reaction on the filtrate of the flat ceramic membrane;
and the phosphorus adsorption packed tower is connected to the permeation side of the hollow fiber membrane MBR reactor and is used for carrying out adsorption dephosphorization treatment on the filtrate of the hollow fiber membrane MBR reactor.
In one embodiment, the contact oxidation tank is filled with spherical packing and provided with an aeration device at the bottom.
In one embodiment, the flat ceramic membrane is a hollow fiber membrane with the membrane aperture of 20-200nm, and the bottom of the flat ceramic membrane is provided with an aeration device.
In one embodiment, the interior of the flat ceramic membrane is a permeate channel, and the permeate channel is connected with a negative pressure pump; a negative pressure control module is also arranged on a pipeline connecting the penetrating fluid channel and the negative pressure pump; the structure of the negative pressure control module comprises: a front duct, a rear duct; the penetrating fluid channel is connected with the vacuum pump through the front pipeline and the rear pipeline in sequence; a penetrating fluid collecting pipe is arranged between the penetrating fluid channel and the front pipeline and is used for discharging the filtrate of the penetrating fluid channel; the outer part of the front pipeline is provided with a fixed cavity, the inner part of the fixed cavity is sleeved with a sliding cavity, the fixed cavity is cylindrical, one end face of the fixed cavity is connected with the front pipeline, the other end face of the fixed cavity is provided with an atmosphere communicating port, the sliding cavity is cylindrical and can axially reciprocate in the fixed cavity, the end face of the sliding cavity back to the atmosphere communicating port is open, the end face of the sliding cavity facing the atmosphere communicating port is also provided with a spring, the spring is positioned in the sliding cavity and connected with the front pipeline, the outer part of the sliding cavity is also provided with a clamping sleeve, the inner part of the fixed cavity is also provided with an elastic separation plate, and when the spring is in a natural state (the spring is not tensioned by external force and is not compressed), the clamping sleeve is positioned on one side of; a first air hole and a second air hole are further formed in one side, back to the rear pipeline, of the sliding cavity, and the first air hole is more inclined to one side of the atmosphere communication port relative to the second air hole; the fixed cavity is also provided with a compressed gas inlet which is attached to the outer wall of the sliding cavity and can be respectively communicated with the first air hole and the second air hole when the sliding cavity reciprocates in the fixed cavity; when the spring is in a natural state, the compressed gas inlet is located at a position between the first air hole and the second air hole, and when the compressed gas inlet is communicated with the first air hole, the second air hole can be communicated with the front pipeline.
In one embodiment, the hollow fiber membrane MBR reactor is equipped with hollow fiber membranes having membrane pore sizes ranging from 20 to 200 nm.
Drawings
FIG. 1 is a diagram of a municipal wastewater treatment system provided by the invention;
FIG. 2 is a process flow for municipal wastewater treatment provided by the present invention;
FIG. 3 is a schematic view of a negative pressure control module;
FIG. 4 is a schematic view of the negative pressure control module;
1. a sand filter; 2. an anaerobic reactor; 3. a contact oxidation pond; 4. a flat ceramic membrane; 5. a negative pressure control module; 6. a negative pressure pump; 7. a hollow fiber membrane MBR reactor; 8. a phosphorus adsorbing packed tower; 9. a permeate collection tube; 10. a front duct; 11. a spring; 12. a compressed gas inlet; 13. a fixed cavity; 14. a slide chamber 14; 15. an elastic barrier plate; 16. an atmosphere communication port; 17. a card sleeve; 18. a first air hole; 19. a second air hole; 20. a rear duct.
Detailed Description
The municipal wastewater to be treated by the invention is mainly domestic sewage in a municipal pipe network, and is firstly subjected to primary sedimentation and then sent to the subsequent treatment steps, and the water quality condition after simple sedimentation is generally as follows:
then, a conventional sand filter is used for primary filtration treatment, and the main function of the sand filter is to remove larger suspended matters in the sand filter. The water quality of the wastewater after sand filtration is generally as shown in the following table:
in some embodiments, in order to improve the treatment effect of the wastewater, coagulation treatment can be performed before the wastewater is subjected to sand filtration, and the coagulant used herein can adopt polyaluminium chloride, ferric chloride, aluminum ferric sulfate and the like. The addition amount of the additive in municipal wastewater can be controlled to be about 50-200 ppm. After coagulation, the COD and turbidity of the waste water can be well reduced. Under normal conditions, the coagulant is prepared into an aqueous agent for online feeding, and the concentration of the coagulant in the aqueous agent can be controlled to be about 5-20 g/L. In addition, in the coagulation process, a reinforced coagulation medicament can be added, the coagulation effect on municipal wastewater can be improved by adopting a cationic organic polymer, the adopted cationic organic polymer can be poly dimethyl diallyl ammonium chloride, the dosage of the poly dimethyl diallyl ammonium chloride is controlled to be 30-90mg/L, and the cationic organic polymer has strong positive charge property, so that the cationic organic polymer has a better reinforced coagulation effect on the municipal wastewater containing more negative charge group humus.
In some embodiments, the coagulation process can be enhanced, and it is found in the present invention that after the coagulant is pretreated by a magnetic field, magnetic moments can be generated on the surface of the concrete in the coagulation process, so that the effect of an electric double layer of the charged concrete is reduced, and the coagulation effect is improved. The magnetic field intensity used here can be controlled at 5-30mT, and the action time of the magnetic field can be controlled at 5-20 min.
After sand filtration treatment, anaerobic treatment is carried out on the wastewater, wherein the anaerobic treatment can adopt some operation methods and equipment in the prior art, the hydraulic retention time is controlled to be more than 24 hours, and the concentration of dissolved oxygen is less than 0.5 mg/L.
After anaerobic treatment, the treatment process adopts contact oxidation treatment, in the treatment process, wastewater enters an oxidation treatment tank filled with filler, and aerobic bacteria activated sludge is added into the treatment tank, so that microorganisms can form a biological film on the surface of the filler to degrade pollutants in the wastewater. The filler used here may be porous plastic balls and aerated at the bottom. In the treatment process, the hydraulic retention time can be controlled within 24-72h, and the dissolved oxygen can be controlled within 1.5-2.5 mg/L.
In the contact oxidation process, the aerobic bacteria can generate sludge, and the sludge can affect the normal operation of the subsequent MBR, so that the sludge is required to be removed from the wastewater after the contact oxidation. If the conventional sedimentation treatment is used, on one hand, the treatment efficiency is not high, and on the other hand, the sludge removal effect of the sedimentation tank is not good. According to the invention, the waste water generated in the contact oxidation process is filtered by the flat ceramic membrane, so that the generated sludge can be better removed, and the treatment efficiency is higher compared with that of a sedimentation tank. Negative pressure is provided from the permeation side of the flat ceramic membrane through a negative pressure suction device, sludge is retained on the outer surface of the flat ceramic membrane after the wastewater after contact oxidation is subjected to filtering treatment of the flat ceramic membrane, and permeation liquid is collected through a permeation liquid channel in the flat ceramic membrane and then discharged. The flat ceramic membrane used herein may be a separation membrane having a pore size of 50 to 800 nm.
In one embodiment, in the process of pumping, since sludge is enriched on the outer surface of the flat membrane, the filter cake outside the flat membrane is continuously thickened and the density is increased, so that the pumping resistance is continuously increased, the negative pressure control module adopted in the invention can automatically regulate and control the surface compaction degree of the ceramic membrane in the negative pressure pumping process, and prevent a sludge layer with overlarge density from being formed on the surface of the flat ceramic membrane, as shown in fig. 3, the internal structure of the negative pressure control module 5 comprises: the inner permeation channel of the flat ceramic membrane 4 is connected with a front pipeline 10 of the negative pressure control module 5, the front pipeline 10 is connected with a rear pipeline 20 in the negative pressure control module 5, and the rear pipeline 20 is connected with the negative pressure pump 6;
a penetrating fluid collecting pipe 9 is arranged between the inner penetrating channel of the flat ceramic membrane 4 and the front pipeline 10;
a fixed cavity 13 is arranged outside the front pipeline 10, a sliding cavity 14 is sleeved inside the fixed cavity 13, the fixed cavity 13 is cylindrical, one end face of the fixed cavity 13 is connected with the front pipeline 10, an atmosphere communication port 16 is arranged on the other end face of the fixed cavity, the sliding cavity 14 is cylindrical and can axially reciprocate in the fixed cavity 13, the end face, back to the atmosphere communication port 16, of the sliding cavity 14 is open, a spring 11 is further arranged on the end face, facing the atmosphere communication port 16, of the sliding cavity 14, the spring 11 is located inside the sliding cavity 14, the spring 11 is connected with the front pipeline 10, a clamping sleeve 17 is further arranged outside the sliding cavity 14, an elastic blocking plate 15 is further arranged inside the fixed cavity 13, and when the spring is in a natural state (the spring is not tensioned by external force and not compressed), the clamping sleeve 17 is located on one side, facing the atmosphere communication port 16, of the elastic blocking plate; a first air hole 18 and a second air hole 19 are further arranged on the side of the sliding cavity 14 facing away from the rear pipeline 20, and the first air hole 18 is more inclined to the side of the atmosphere communication port 16 than the second air hole 19; a compressed gas inlet 12 is further arranged on the fixed cavity 13, the compressed gas inlet 12 is attached to the outer wall of the sliding cavity 14, and can be respectively communicated with the first air hole 18 and the second air hole 19 when the sliding cavity 14 reciprocates in the fixed cavity 13; when the spring is in a natural state, the compressed gas inlet port 12 is located at a position intermediate the first air hole 18 and the second air hole 19, and when the compressed gas inlet port 12 communicates with the first air hole 18, the second air hole 19 can communicate with the front duct 10.
The compressed gas inlet 12 is connected to an external compressed gas source; the rear pipe 20 is connected to the negative pressure pump 6.
After the negative pressure pump 6 is started, the permeation channel inside the flat ceramic membrane 5 can be made to be negative pressure, so that the wastewater treated by the contact oxidation pond permeates to the internal channel through the outside of the flat ceramic membrane 5, the sludge is attached to the outside of the flat ceramic membrane 5, the sludge density is continuously compacted along with continuous pumping due to the accumulation of the sludge outside the flat ceramic membrane 5, the inflow of water is blocked, the vacuum degree in the sliding cavity 14 is increased, the atmosphere communicating port 16 is arranged on the fixed cavity 13 and communicated with the atmosphere, the external atmosphere presses the sliding cavity 14 to generate a deformation trend towards the left side in the figure, the clamping sleeve 17 is blocked by the elastic blocking plate 15, and the deformation force borne by the elastic blocking plate 15 is increased along with the increase of the internal vacuum degree until the clamping sleeve 17 cannot be blocked continuously, the slide chamber 14 is slid to the left side, and the changed structure is as shown in fig. 4. At the moment, the compressed gas inlet 12 is communicated with the first air hole 18, the second air hole 19 can be communicated with the front pipeline 10, and the high negative pressure on the flat ceramic membrane 5 is eliminated through the internal pressure balance effect, so that the sludge accumulated on the outer surface of the flat ceramic membrane 5 is not compacted by the negative pressure any more, becomes loose and falls downwards, and the problem of forming a compact sludge layer on the surface of the flat ceramic membrane 5 is avoided; when the spring 11 suddenly breaks free of the blocking of the elastic blocking plate 15, a deformation potential energy is generated to return to a rightward state, and meanwhile, when the compressed gas inlet 12 is communicated with the first gas hole 18, the second gas hole 19 is communicated with the front pipeline 10, so that the pressure in the sliding cavity 14 is continuously increased, and the sliding cavity 14 is changed to move rightward through the dual functions of pressure and spring deformation recovery, so that the clamping sleeve 17 restores to the state shown in fig. 3 again after pressing the elastic blocking plate 15, and a movement cycle is completed; by such a circulation action, the negative pressure applied to the flat ceramic membrane 5 is not always kept stable, but a periodic change is generated, that is, the sludge on the outer surface of the flat ceramic membrane is not always compacted, but a dense-loose change of the structure occurs along with the periodic pressure change, so that the sludge is easier to drop and remove.
After the filtrate of the flat ceramic membrane is obtained, performing membrane biological reaction on the wastewater through a conventional MBR, and during treatment, aerating at the bottom of the MBR for increasing the dissolved oxygen in the water, wherein the aeration can be generally controlled at 2-4mg/L, and the MLSS of the wastewater can be controlled at about 5000-20000 mg/L. Hollow fiber membranes with membrane pore sizes of 20-200nm can be used in MBR reactors. The hydraulic retention time of the operation process can be controlled between 12 and 36 hours.
The total nitrogen, COD and ammonia nitrogen in the wastewater after the MBR reaction can be obviously reduced, but the removal of the total phosphorus is not ideal, and the purpose of deeply removing the total phosphorus can be realized by passing the wastewater through a bed layer of a phosphorus adsorbent. The dephosphorizing adsorbent used in the method can be obtained by mixing and calcining materials such as fly ash, quicklime, phosphogypsum and the like.
Based on the above method, the processing apparatus provided by the present invention, as shown in fig. 1, includes:
the sand filter 1 is used for filtering the wastewater;
the anaerobic reactor 2 is connected with the sand filter 1 and is used for carrying out anaerobic decomposition treatment on the filtrate obtained in the sand filter 1;
a contact oxidation tank 3 connected to the anaerobic reactor 2 for performing contact oxidation treatment on the wastewater obtained in the anaerobic reactor 2; the contact oxidation tank 3 is provided with a suspended filler;
the flat ceramic membrane 4 is connected to the contact oxidation tank 3 and is used for filtering the wastewater obtained in the contact oxidation tank 3 to remove sludge;
a hollow fiber membrane MBR reactor 7 connected to the permeation side of the flat ceramic membrane 4 and used for carrying out MBR reaction on the filtrate of the flat ceramic membrane 4;
and the phosphorus adsorption packed tower 8 is connected to the permeation side of the hollow fiber membrane MBR reactor 7 and is used for carrying out adsorption dephosphorization treatment on the filtrate of the hollow fiber membrane MBR reactor 7.
In one embodiment, the contact oxidation tank 3 is filled with spherical packing and provided with an aeration device at the bottom.
In one embodiment, the flat ceramic membrane 4 is a hollow fiber membrane with a membrane pore size of 20-200nm, and the bottom is provided with an aeration device.
In one embodiment, the interior of the flat ceramic membrane 4 is a permeate channel, which is connected to a negative pressure pump 6; a negative pressure control module 5 is also arranged on a pipeline connecting the penetrating fluid channel and the negative pressure pump 6; the structure of the negative pressure control module 5 comprises: a front duct 10, a rear duct 20; the penetrating fluid channel is connected to the vacuum pump through a front pipeline 10 and a rear pipeline 20 in sequence; a permeate collecting pipe 9 is provided between the permeate passage and the front pipe 10 for discharging the filtrate of the permeate passage; a fixed cavity 13 is arranged outside the front pipeline 10, a sliding cavity 14 is sleeved inside the fixed cavity 13, the fixed cavity 13 is cylindrical, one end face of the fixed cavity 13 is connected with the front pipeline 10, an atmosphere communication port 16 is arranged on the other end face of the fixed cavity, the sliding cavity 14 is cylindrical and can axially reciprocate in the fixed cavity 13, the end face, back to the atmosphere communication port 16, of the sliding cavity 14 is open, a spring 11 is further arranged on the end face, facing the atmosphere communication port 16, of the sliding cavity 14, the spring 11 is located inside the sliding cavity 14, the spring 11 is connected with the front pipeline 10, a clamping sleeve 17 is further arranged outside the sliding cavity 14, an elastic blocking plate 15 is further arranged inside the fixed cavity 13, and when the spring is in a natural state (the spring is not tensioned by external force and not compressed), the clamping sleeve 17 is located on one side, facing the atmosphere communication port 16, of the elastic blocking plate; a first air hole 18 and a second air hole 19 are further arranged on the side of the sliding cavity 14 facing away from the rear pipeline 20, and the first air hole 18 is more inclined to the side of the atmosphere communication port 16 than the second air hole 19; a compressed gas inlet 12 is further arranged on the fixed cavity 13, the compressed gas inlet 12 is attached to the outer wall of the sliding cavity 14, and can be respectively communicated with the first air hole 18 and the second air hole 19 when the sliding cavity 14 reciprocates in the fixed cavity 13; when the spring is in a natural state, the compressed gas inlet port 12 is located at a position intermediate the first air hole 18 and the second air hole 19, and when the compressed gas inlet port 12 communicates with the first air hole 18, the second air hole 19 can communicate with the front duct 10.
In one embodiment, hollow fiber membrane MBR reactor 7 is equipped with hollow fiber membranes having membrane pore sizes in the range of 20-200 nm.
In the following examples, the treated wastewater was derived from a municipal community wastewater network and had the following quality:
COD 350-380mg/L, SS 220-245mg/L, ammonia nitrogen 35-40mg/L, total nitrogen 50-55 mg/L, total phosphorus 7-8mg/L and turbidity 75-78 NTU.
In the following examples, the detection methods used are as follows: total nitrogen (spectrophotometry), total phosphorus (vanadium molybdenum phosphoric acid colorimetry), MLSS (weighing method), nitrogen (spectrophotometry), COD (potassium dichromate method), turbidity (nephelometer), dissolved oxygen (dissolved oxygen meter)
Example 1
After the wastewater is simply precipitated, adding an iron chloride coagulant (a water aqua prepared in advance to be 10 g/L) into the upper layer liquid, controlling the concentration of the coagulant in the wastewater to be 120ppm, forming alum floc after coagulation, and then sending the alum floc into a sand filter to remove the concrete; sending the filtrate of the sand filtration into an anaerobic reactor for anaerobic reaction, keeping the hydraulic retention time at about 30h, and keeping the concentration of dissolved oxygen below 0.45 mg/L; after the reaction, carrying out contact oxidation on the wastewater to form suspended fillers in a contact oxidation tank, aerating at the bottom to control the dissolved oxygen to be 2.5-3mg/L, and adding activated sludge into the contact oxidation tank for conventional domestication before starting; and (2) feeding the wastewater after the contact oxidation treatment into a flat ceramic membrane for filtering (adopting a 200nm ceramic flat membrane) to remove generated sludge, reacting the filtrate of the flat membrane by adopting an MBR (membrane bioreactor), aerating at the bottom of the MBR, adopting hollow fiber membrane filaments with an average pore diameter of 45nm in the interior, controlling the dissolved oxygen to be 3-3.2mg/L, and keeping the hydraulic retention time for 36h, and deeply removing phosphorus from the treated wastewater in a packed tower filled with a phosphorus adsorbent.
Example 2
The difference from example 1 is that: before the coagulation process, the ferric chloride water aqua is treated for 15min under the condition of 20mT through an electromagnetic field, so that the coagulant is magnetized.
After the wastewater is simply precipitated, adding an iron chloride coagulant (pre-prepared into a water agent of 10g/L, treating for 15min under the condition of 20mT, magnetizing the coagulant), controlling the concentration of the coagulant in the wastewater to be 120ppm, forming alum floc after coagulation, and then sending the alum floc into a sand filter to remove the concrete; sending the filtrate of the sand filtration into an anaerobic reactor for anaerobic reaction, keeping the hydraulic retention time at about 30h, and keeping the concentration of dissolved oxygen below 0.45 mg/L; after the reaction, carrying out contact oxidation on the wastewater to form suspended fillers in a contact oxidation tank, aerating at the bottom to control the dissolved oxygen to be 2.5-3mg/L, and adding activated sludge into the contact oxidation tank for conventional domestication before starting; and (2) feeding the wastewater after the contact oxidation treatment into a flat ceramic membrane for filtering (adopting a 200nm ceramic flat membrane) to remove generated sludge, reacting the filtrate of the flat membrane by adopting an MBR (membrane bioreactor), aerating at the bottom of the MBR, adopting hollow fiber membrane filaments with an average pore diameter of 45nm in the interior, controlling the dissolved oxygen to be 3-3.2mg/L, and keeping the hydraulic retention time for 36h, and deeply removing phosphorus from the treated wastewater in a packed tower filled with a phosphorus adsorbent.
Example 3
The difference from example 3 is that: in the coagulation process, a strengthening coagulant of poly dimethyl diallyl ammonium chloride is added at the same time, wherein the concentration is 40mg/L in the wastewater.
After the wastewater is simply precipitated, adding an iron chloride coagulant (a water agent prepared in advance to be 10g/L, treating for 15min under the condition of 20mT and magnetizing the coagulant) and 40mg/L poly-dimethyl diallyl ammonium chloride into the upper layer of liquid, controlling the concentration of the coagulant in the wastewater to be 120ppm, forming alum floc after coagulation, and then sending the alum floc into a sand filter to remove the concrete; sending the filtrate of the sand filtration into an anaerobic reactor for anaerobic reaction, keeping the hydraulic retention time at about 30h, and keeping the concentration of dissolved oxygen below 0.45 mg/L; after the reaction, carrying out contact oxidation on the wastewater to form suspended fillers in a contact oxidation tank, aerating at the bottom to control the dissolved oxygen to be 2.5-3mg/L, and adding activated sludge into the contact oxidation tank for conventional domestication before starting; and (2) feeding the wastewater after the contact oxidation treatment into a flat ceramic membrane for filtering (adopting a 200nm ceramic flat membrane) to remove generated sludge, reacting the filtrate of the flat membrane by adopting an MBR (membrane bioreactor), aerating at the bottom of the MBR, adopting hollow fiber membrane filaments with an average pore diameter of 45nm in the interior, controlling the dissolved oxygen to be 3-3.2mg/L, and keeping the hydraulic retention time for 36h, and deeply removing phosphorus from the treated wastewater in a packed tower filled with a phosphorus adsorbent.
In the above examples, the water quality of the produced water after coagulation treatment and finally obtained is shown in the following table:
as can be seen from the table above, after the comprehensive treatment, indexes such as COD, total nitrogen and total phosphorus in the municipal wastewater are all obviously reduced, and the indexes meet the national GB18918-2002 pollutant discharge Standard of urban Sewage treatment plants. In example 2, compared to example 1, the magnetic field is used to magnetize the coagulant, so that the coagulant is magnetized to form a magnetic moment, and the electric double layer on the surface of the concrete is more easily inhibited during coagulation, thereby improving the coagulation effect and improving the removal rate of indexes such as COD, turbidity, total nitrogen and the like. In the embodiment 3, the cationic polymer is adopted for strengthening coagulation, and the cationic polymer acts with negatively charged humus in municipal wastewater, so that the removal rate of relevant indexes of wastewater coagulation is improved.
Claims (9)
1. A municipal wastewater treatment method is characterized by comprising the following steps:
step 1, pre-filtering municipal wastewater, and then carrying out anaerobic decomposition treatment on filtrate;
step 2, carrying out contact oxidation treatment on the wastewater subjected to anaerobic decomposition in the step 1;
step 3, filtering sludge from the wastewater after the contact oxidation treatment;
step 4, performing aerobic decomposition treatment on the filtrate obtained in the step 3 by adopting an MBR (membrane bioreactor);
and 5, adsorbing and removing phosphorus from the wastewater obtained in the 4 step by using a phosphorus adsorption packed tower.
2. The method of claim 1, wherein in one embodiment, prior to the 1 st step of sand filtering, coagulation of the wastewater is further required;
in one embodiment, a coagulant is added in the coagulation treatment, and the coagulant is selected from polyaluminium chloride, ferric chloride, aluminum ferric sulfate and the like;
in one embodiment, the addition amount of the coagulant in the wastewater is about 50-200 ppm;
in one embodiment, in the coagulation treatment, a reinforced coagulant is also required to be added, wherein the reinforced coagulant is a cationic organic polymeric flocculant;
the cationic organic polymer is selected from poly dimethyl diallyl ammonium chloride.
3. The municipal wastewater treatment method according to claim 2, wherein in one embodiment, the amount of the coagulant aid added to the wastewater is controlled to be about 30 to 90 mg/L;
in one embodiment, the coagulant is magnetized by a magnetic field before being added into the wastewater, the magnetic field intensity can be controlled to be 5-30mT, and the action time of the magnetic field can be controlled to be 5-20 min;
in one embodiment, the hydraulic retention time of the anaerobic treatment process in step 1 is controlled to be more than 24 hours, and the dissolved oxygen concentration is less than 0.5 mg/L.
4. The method for treating municipal wastewater according to claim 1, wherein in step 2, the reactor for the contact oxidation treatment is packed with packing, the bottom of the reactor is aerated, the hydraulic retention time is controlled to 24 to 72 hours, and the dissolved oxygen is controlled to 1.5 to 2.5 mg/L;
in one embodiment, in step 3, the waste water after the contact oxidation treatment is filtered by using a flat ceramic membrane, wherein a penetrating fluid channel is formed inside the flat ceramic membrane, and the penetrating fluid is pumped to the flat ceramic membrane by connecting to a negative pressure pump.
5. The method for treating municipal wastewater according to claim 1, wherein in step 4, the MBR is aerated to have a dissolved oxygen content of 2-4mg/L, the wastewater MLSS is controlled at about 5000-20000mg/L, hollow fiber membranes with a membrane pore size of 20-200nm are used in the MBR, and the hydraulic retention time during operation is controlled at 12-36 h.
6. A municipal wastewater treatment system, comprising:
the sand filter (1) is used for filtering the wastewater;
the anaerobic reactor (2) is connected with the sand filter (1) and is used for carrying out anaerobic decomposition treatment on the filtrate obtained in the sand filter (1);
the contact oxidation tank (3) is connected with the anaerobic reactor (2) and is used for carrying out contact oxidation treatment on the wastewater obtained in the anaerobic reactor (2); a suspension filler is arranged in the contact oxidation tank (3);
the flat ceramic membrane (4) is connected to the contact oxidation tank (3) and is used for filtering the wastewater obtained in the contact oxidation tank (3) to remove sludge;
the hollow fiber membrane MBR reactor (7) is connected to the permeation side of the flat ceramic membrane (4) and is used for carrying out MBR reaction on the filtrate of the flat ceramic membrane (4);
and the phosphorus adsorption packed tower (8) is connected to the permeation side of the hollow fiber membrane MBR (7) and is used for carrying out adsorption dephosphorization treatment on the filtrate of the hollow fiber membrane MBR (7).
7. The municipal wastewater treatment system according to claim 6, wherein in one embodiment, the contact oxidation tank 3 is packed with spherical packing and the bottom is provided with aeration means
The municipal wastewater treatment system according to claim 6, wherein the flat ceramic membrane (4) comprises hollow fiber membranes having a membrane pore size of 20 to 200nm and an aeration means at the bottom.
8. The municipal wastewater treatment system according to claim 6, wherein in one embodiment, the inside of the flat ceramic membrane (4) is a permeate channel, and the permeate channel is connected to a negative pressure pump (6); a negative pressure control module (5) is also arranged on a pipeline connecting the penetrating fluid channel and the negative pressure pump (6); the structure of the negative pressure control module (5) comprises: a front duct (10), a rear duct (20); the penetrating fluid channel is connected with the vacuum pump through a front pipeline (10) and a rear pipeline (20) in sequence; a permeate collecting pipe (9) is arranged between the permeate channel and the front pipeline (10) and is used for discharging the filtrate of the permeate channel; a fixed cavity (13) is arranged outside the front pipeline (10), a sliding cavity (14) is sleeved inside the fixed cavity (13), the fixed cavity (13) is cylindrical, one end face of the fixed cavity is connected with the front pipeline (10), an atmosphere communication port (16) is arranged on the other end face of the fixed cavity, the sliding cavity (14) is cylindrical and can reciprocate in the fixed cavity (13) along the axial direction, the end face, back to the atmosphere communication port (16), of the sliding cavity (14) is open, a spring (11) is further arranged on the end face, facing the atmosphere communication port (16), of the sliding cavity (14), the spring (11) is located inside the sliding cavity (14), the spring (11) is connected with the front pipeline (10), a clamping sleeve (17) is further arranged outside the sliding cavity (14), an elastic blocking plate (15) is further arranged inside the fixed cavity (13), when the spring is in a natural state, the clamping sleeve (17) is located on the side, facing the atmosphere communication port (16), of the elastic blocking plate (15), and the sliding cavity (14) is located on the side A first air hole (18) and a second air hole (19) are further formed in one side of the rear pipeline (20), and the first air hole (18) is closer to the side of the atmosphere communication opening (16) than the second air hole (19); the fixed cavity (13) is also provided with a compressed gas inlet (12), the compressed gas inlet (12) is attached to the outer wall of the sliding cavity (14), and the sliding cavity (14) can be respectively communicated with the first air hole (18) and the second air hole (19) when reciprocating in the fixed cavity (13); when the spring is in a natural state, the compressed gas inlet port (12) is located at a position intermediate the first gas hole (18) and the second gas hole (19), and when the compressed gas inlet port (12) is communicated with the first gas hole (18), the second gas hole (19) can be communicated with the front duct (10).
9. The municipal wastewater treatment system according to claim 6, wherein in one embodiment, hollow fiber membrane MBR reactor (7) is equipped with hollow fiber membranes having membrane pore sizes of 20-200 nm.
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| CN113429064A (en) * | 2021-06-03 | 2021-09-24 | 泉州市安平碧海环保科技有限公司 | Buried AO process and high-load dephosphorization wetland system |
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