Method for centralized treatment of scattered wastewater

Abstract

The invention provides a scattered wastewater centralized treatment method, and belongs to the technical field of sewage treatment.The treatment method comprises the following steps that S1, wastewater from various sources is classified and stored; s2, mixing in a reaction tank in proportion according to the type of the wastewater, then carrying out aeration stirring, and adjusting the pH to be acidic to obtain mixed wastewater; s3, carrying out iron-carbon micro-electrolysis treatment on the mixed wastewater to obtain treated wastewater, and enabling the treated wastewater to automatically flow into a sedimentation tank; s4, adjusting the pH value of the treated wastewater to be alkaline, then carrying out delayed aeration treatment, then carrying out coagulating sedimentation, and separating mud from water after the sedimentation is finished; s5, carrying out aeration stirring on the clear liquid, then introducing primary SAO3 ozone for catalytic oxidation, carrying out biochemical treatment by using activated sludge to obtain second treated wastewater, and carrying out sludge-water separation; s6, aerating and stirring the supernate, introducing secondary SAO3 for catalytic ozonation, and discharging into a buffer water tank; s7, the wastewater is cached in a discharge water tank, and sludge is packaged and subjected to outsourcing treatment after being subjected to gravity concentration; the method can be used for simultaneously treating various kinds of wastewater, and energy consumption and cost are remarkably reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to a method for centralized treatment of scattered wastewater. Background Art

[0002] Scattered wastewater refers to wastewater generated in industrial production, commercial operations or other activities, which is small in quantity, scattered and discharged irregularly. Wastewater mainly comes from small factories or workshops, laboratories, small chemical plants without supporting sewage receiving plants, etc., such as: small amounts of production wastewater from hardware processing, electroplating, small printing, catering, scientific research and testing laboratories, pharmaceuticals, chemical industries, etc. The amount of this type of wastewater is unstable, and the discharge time and amount are irregular. At the same time, due to the diverse sources, it may contain various pollutants, such as heavy metals, organic matter, acid and alkali substances, etc., resulting in complex wastewater composition and great difficulty in treatment. Enterprises lack economies of scale in self-built sewage treatment stations, with large investments, short actual production operation time, and long periods of non-operation. The input-output ratio is seriously unbalanced. Therefore, most enterprises that generate scattered wastewater choose to directly dispose of the wastewater as hazardous waste. The disposal cost of one ton of water is as high as several thousand yuan, which is also very uneconomical for enterprises. Therefore, in view of the complex water quality, unstable water volume, and great difficulty in treatment of scattered wastewater, it is urgent to propose a centralized treatment process with broad spectrum, impact resistance, and strong stability to achieve the standard treatment and discharge of scattered wastewater. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a method for centralized treatment of scattered wastewater, which can cope with complex wastewater quality, can remove substances including heavy metals, biological toxic and harmful substances, and can oxidize and decompose large molecular organic matter in the wastewater, reduce the treatment load of the biochemical system, improve the biodegradability of the wastewater, reduce the residence time of the biochemical system, and save a lot of energy and cost.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] In a first aspect, the present invention provides a method for centralized treatment of scattered wastewater, comprising the following steps:

[0006] S1. Separate and store wastewater from various sources;

[0007] S2. Mix the wastewater in a reaction tank in proportion according to the type of wastewater, aerate and stir, and adjust the pH to acidic to obtain mixed wastewater;

[0008] S3. The mixed wastewater is subjected to iron-carbon micro-electrolysis treatment to obtain a first treated wastewater which then flows by gravity into a first sedimentation tank;

[0009] The present invention removes heavy metals, petroleum, animal and plant oils, and toxic and harmful substances in wastewater through iron-carbon micro-electrolysis treatment, decomposes macromolecular refractory organic matter into small molecular substances, removes part of COD, and improves the biodegradability of wastewater.

[0010] S4. The first treated wastewater is adjusted to an alkaline pH and then subjected to delayed aeration treatment, and then PAC and PAM are added for coagulation and sedimentation. After the sedimentation is completed, the mud and water are separated to obtain a first supernatant and lower sludge; the first supernatant is transferred to a first transfer water tank for temporary storage, and the lower sludge is discharged to a sludge tank;

[0011] The present invention adjusts the pH to alkaline by adding alkali to react with iron-carbon to dissolve ferrous ions in wastewater to form ferrous hydroxide, and then converts the ferrous hydroxide into ferric hydroxide through delayed aeration, and then sequentially adds PAC and PAM for coagulation and precipitation.

[0012] S5. The first supernatant is aerated and stirred, and then introduced into the primary SAO3 ozone for catalytic oxidation to obtain the second treated wastewater, and then flows to the biochemical treatment system to be biochemically treated with activated sludge to obtain the third treated wastewater, and then flows to the second sedimentation tank to separate the mud and water to obtain the second supernatant and the lower sludge; the second supernatant is transferred to the second transfer water tank for temporary storage, and the lower sludge is discharged to the sludge tank;

[0013] The present invention utilizes hydroxyl radicals generated by ozone under the catalytic action of a catalyst to further indiscriminately oxidize and decompose organic matter in the wastewater, thereby removing a portion of pollutants and further improving the biodegradability of the wastewater; and utilizes the metabolism of microorganisms in activated sludge to decompose pollutants in the wastewater, thereby further purifying the wastewater.

[0014] S6. The second supernatant is aerated and stirred and passed into the secondary SAO3 ozone catalytic oxidation to obtain the fourth treated wastewater, which meets the sewage treatment plant pipe standard and is then discharged into the buffer tank;

[0015] S7. The treated and purified wastewater is buffered in the discharge pool and eventually discharged evenly in compliance with the standards. The sludge in the sludge pool is concentrated by gravity and then pumped into the plate filter press for filtration and dehydration. The filtrate is returned to the wastewater mixing reaction pool and the dehydrated sludge is packaged and outsourced for disposal.

[0016] Preferably, the wastewater in S1 is one or more of high-salt wastewater, high-COD wastewater, high-ammonia nitrogen wastewater, strong acid and strong alkali wastewater, electroplating wastewater containing heavy metals, and oily wastewater; and is classified and stored according to the COD, ammonia nitrogen index range, acidity and alkalinity of the wastewater, and whether it contains oil.

[0017] Preferably, the COD concentration of the mixed wastewater in S2 is between 3000 and 8000 mg / L, the ammonia nitrogen concentration is between 500 and 2000 mg / L, and the petroleum concentration is between 0 and 100 mg / L.

[0018] Preferably, the wastewater in S2 is adjusted to a pH value of 1 to 6; and the regulator is sulfuric acid.

[0019] Preferably, the iron-carbon micro-electrolysis treatment in S3 is carried out using an FCM-IV iron-carbon micro-electrolysis device, and the wastewater reaction residence time is 1 to 10 hours;

[0020] The FCM-IV iron-carbon micro-electrolysis device consists of a reactor, water distribution, gas distribution, backwash gas distribution, pebble filler and iron-carbon micro-electrolysis filler. The pebble filling specifications are φ32-16mm, φ16-8mm, and φ8-4mm, and the filling height of each specification is 30cm. The specifications are arranged from large to small from the bottom to the top. The upper part of the pebbles is filled with iron-carbon micro-electrolysis filler, and the filling height is 2 to 4m.

[0021] For the composition and preparation of FCM-Ⅳ iron-carbon micro-electrolysis materials, the structure of the micro-electrolysis reactor, and the layout of FCM-Ⅳ iron-carbon micro-electrolysis materials inside the micro-electrolysis tower, please refer to the patent: A micro-electrolysis catalytic oxidation tower (ZL201620494687.3)

[0022] Preferably, the pH value is adjusted to 7-11 in S4;

[0023] Delayed aeration time is 1-3h;

[0024] The dosage of PAC is 100-1000 mg / L, and the dosage of PAM is 5-20 mg / L.

[0025] Preferably, the temporary retention time of the first supernatant in S4 in the first transfer water tank is 1 to 5 hours.

[0026] Preferably, the wastewater reaction residence time in the primary SAO3 ozone catalytic oxidation in S5 is 1 to 10 hours, and the ozone dosage is 100 to 2000 mg / L;

[0027] The first-stage SAO3 ozone catalytic oxidation device consists of an ozone catalytic oxidation reactor, water distribution, gas distribution, backwashing, pebbles and ozone-specific catalysts. The pebbles are filled with specifications of φ32-16mm, φ16-8mm, and φ8-4mm, and the filling height of each specification is 30cm. The specifications are from large to small from the bottom to the top. The upper part of the pebbles is filled with SAO3 ozone catalyst filler, and the filling height is 2 to 4m.

[0028] The ozone catalytic oxidation reactor is filled with SAO3 ozone catalyst. The structure and internal layout of the ozone catalytic oxidation tower refer to the patent: Ozone delivery device (ZL201721138834.4).

[0029] Preferably, the biochemical treatment system in S5 sequentially performs treatment in an anaerobic tank, an anoxic tank, and an aerobic tank.

[0030] Preferably, the temporary storage time of the No. 2 transfer pool in S5 is 1 to 5 hours.

[0031] Preferably, the residence time of the secondary SAO3 ozone catalytic oxidation reaction in S6 is 0.5 to 5 h, and the ozone dosage is 50 to 200 mg / L.

[0032] Preferably, the discharge pool in S7 has a buffer residence time of 2 to 4 hours; the sludge filter pressing requires conditioning of the sludge before filtration, and the conditioning method can be adding PAM for stirring, and the PAM dosage is 10 to 100 mg / L.

[0033] Contains at least the following beneficial technical effects:

[0034] 1. The present invention sequentially adopts two advanced oxidation technologies, namely FCM-IV iron-carbon micro-electrolysis and SAO3 ozone catalytic oxidation. The two technologies work synergistically to cope with complex wastewater quality and can remove substances including heavy metals, biological toxic and harmful substances. At the same time, they can oxidize and decompose macromolecular organic matter in the wastewater, reduce the processing load of the biochemical system, improve the biodegradability of the wastewater, and reduce the residence time of the biochemical system, thereby reducing the floor space and civil engineering investment.

[0035] 2. The process adopted in the present invention can realize the centralized treatment of scattered wastewater and can ensure that the treatment meets the discharge standards. The treatment cost per ton of water is about 200 yuan. Compared with the direct disposal of hazardous waste by the enterprise, the cost saving per ton of water ranges from 1,000 to 3,000 yuan. It has good economic benefits and creates a business environment for legal production, cost reduction and revenue increase for small and medium-sized enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is the process flow chart of wastewater treatment. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0038] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0039] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the main idea or essential features of the present invention. Therefore, from all points of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any reference numerals in the claims should not be regarded as limiting the claims involved.

[0040] In addition, it should be understood that although this specification is described according to the implementation modes, not every implementation mode includes only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. These other implementation modes are also covered within the protection scope of the present invention.

[0041] It should also be understood that the specific embodiments described above are only used to explain the present invention, and the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, can make equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, which should be covered by the protection scope of the present invention / invention.

[0042] Example 1

[0043] This embodiment is a centralized treatment project for scattered wastewater in Shizuishan City, Ningxia. The project construction scale is 300m3 / d, serving 20 enterprises. The wastewater includes coal chemical, pharmaceutical, petrochemical and other types. The wastewater is high-salt and high-organic concentration difficult to degrade industrial wastewater.

[0044] The process flow of this embodiment refers to Figure 1 , comprising the following steps:

[0045] S1. After testing and analysis, scattered wastewater collected from enterprises is classified into high COD, high ammonia nitrogen, strong acid, strong alkali, oil content, etc. and stored in the warehouse;

[0046] S2. According to the designed influent index: COD concentration 5000-6000mg / L, ammonia nitrogen concentration 1000-1500mg / L, petroleum concentration 0-100mg / L, add wastewater with different indexes into the compatibility reaction tank, aerate and stir evenly, add sulfuric acid to adjust the pH to 2.5, and mix evenly to obtain the mixed liquid;

[0047] S3, passing the mixed liquor into the FCM-IV iron-carbon micro-electrolysis device, the wastewater is reacted in the device for 4 hours, and aeration reaction is performed to obtain the first treated wastewater; the structure of the FCM-IV iron-carbon micro-electrolysis device is as follows: three pebbles of specifications φ32-16mm, φ16-8mm, and φ8-4mm are filled with 30cm respectively, and the iron-carbon micro-electrolysis filler is filled with 3m;

[0048] S4, the first treated wastewater flows by gravity to the neutralization delayed aeration coagulation sedimentation device, adds alkali to adjust the pH to 8, aerates for 2h, then adds PAC 200mg / L and PAM 10mg / L for stirring and coagulation, and then enters the sedimentation area for mud-water separation to obtain the supernatant, and the sludge is discharged into the sludge tank to obtain the first supernatant and lower sludge;

[0049] S5, the first supernatant flows into the No. 1 transfer pool by gravity, and the residence time is 2 hours;

[0050] S6. A first-level SAO3 ozone catalytic oxidation device is introduced into the first supernatant. The wastewater is allowed to react in the device for 4 hours. 500 mg / L ozone is introduced for full reaction to obtain the second treated wastewater. The filling height of the SAO3 ozone catalyst is 4 m.

[0051] S7, the second treated wastewater flows into the biochemical system by gravity, and is biochemically treated in the anaerobic tank, the anoxic tank, and the aerobic tank respectively, to obtain the third treated wastewater;

[0052] S8, the third treated wastewater flows into the second sedimentation tank by gravity, and the effective residence time of the second sedimentation tank is 3h. The mud and water are separated under the action of gravity sedimentation to obtain the second supernatant and the lower sludge;

[0053] S9, the second supernatant flows to the No. 2 transfer pool by gravity, and the residence time is 2 hours;

[0054] S10, the second supernatant is passed into a secondary SAO3 ozone catalytic oxidation device, the SAO3 ozone catalyst filling height is 4m, the reaction residence time is 1h, and 100mg / L ozone is passed into the device for full reaction to obtain the fourth treated wastewater;

[0055] S11, the fourth treated wastewater flows into the discharge pool for buffering, with a retention time of 2h, and the COD is detected to be ≤500mg / L, and the discharge meets the standard;

[0056] S12, neutralization delayed aeration coagulation sedimentation and secondary sedimentation tank sludge are discharged to the sludge pool regularly, and after adding 20mg / LPAM solution for conditioning, they are passed into the plate filter press for filtration and dehydration. The filtrate is returned to the matching reaction tank, and the dehydrated sludge is outsourced for disposal.

[0057] This embodiment solves the problem of difficult wastewater treatment in local enterprises, especially for cyclical production enterprises. After the enterprises invest in environmental protection equipment, the equipment is often out of service during the off-season, and the maintenance cost is high. Without investment in the purchase of environmental protection equipment, general sewage treatment plants cannot directly accept the wastewater generated by the enterprises, so they need to be disposed of as hazardous waste, and the treatment cost is as high as 1,000 to 2,000 yuan per ton, which is very uneconomical. After the completion of this embodiment, various types of industrial wastewater are treated in a targeted manner, the wastewater collection scale is large, the source is stable, and there is a scale effect. The cost of treating a ton of water is reduced to 150 to 200 yuan, which saves a lot of disposal costs for the enterprises, and at the same time saves the investment cost of environmental protection equipment. In addition, in terms of the ecological environment, it reduces the risk of illegal discharge by enterprises, and has good social and economic value.

[0058] Example 2

[0059] This example is a centralized treatment project for scattered wastewater in a certain place in Zibo City, Shandong Province. The project construction scale is 200m3 / d, serving 30 enterprises. The wastewater includes fine chemicals, pharmaceuticals, petrochemicals, etc. The wastewater belongs to high-salt and high-organic concentration difficult to degrade industrial wastewater. The treatment method is basically the same as that of Example 1, except that:

[0060] In step S2, the water inlet indicators designed in this case are: COD concentration is 7000-8000 mg / L, ammonia nitrogen concentration is 1500-2000 mg / L, and petroleum concentration is 0-50 mg / L.

[0061] In step S3, the iron-carbon micro-electrolysis filler is filled to 2.5 m, and the wastewater reacts in the device for 5 h;

[0062] In step S6, the filling height of SAO3 ozone catalyst is 3m, the reaction residence time of wastewater in the device is 6h, and the ozone dosage is 1000mg / L;

[0063] In step S10, the filling height of SAO3 ozone catalyst is 3m, the reaction residence time of wastewater in the device is 2h, and the ozone dosage is 400mg / L.

[0064] Example 3

[0065] This example is a centralized wastewater treatment project in Dongguan City, with a construction scale of 500m

[0066] / d, serving 50 enterprises, the wastewater includes electroplating, circuit board, printing and other types, the wastewater belongs to industrial wastewater containing heavy metals, toxic and harmful substances. The treatment method is basically the same as that of Example 1, the difference is:

[0067] In step S2, the water inlet indicators designed in this case are: COD concentration is 3000-4000 mg / L, ammonia nitrogen concentration is 500-1000 mg / L, and petroleum concentration is 0-30 mg / L.

[0068] In step S3, the iron-carbon micro-electrolysis filler is filled with 4m, and the wastewater reacts in the device for 2h;

[0069] In step S6, the filling height of SAO3 ozone catalyst is 2m, the reaction residence time of wastewater in the device is 3h, and the ozone dosage is 400mg / L;

[0070] In step S10, the filling height of SAO3 ozone catalyst is 2m, the reaction residence time of wastewater in the device is 2h, and the ozone dosage is 300mg / L.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for centralized treatment of scattered wastewater, characterized in that: The following steps are involved: S1. Separate and store wastewater from various sources; S2. Mix the wastewater in a reaction tank in proportion according to the type of wastewater, then aerate and stir and adjust the pH to acidic to obtain mixed wastewater; S3. The mixed wastewater is subjected to iron-carbon micro-electrolysis treatment to obtain a first treated wastewater which then flows by gravity into a first sedimentation tank; S4. The pH of the first treated wastewater is adjusted to alkaline and then subjected to delayed aeration treatment, and then polyaluminium chloride and polyacrylamide are added for coagulation and precipitation, and after the precipitation is completed, the mud and water are separated to obtain a first supernatant and lower sludge; the first supernatant is transferred to a first transfer water tank for temporary storage, and the lower sludge is discharged to a sludge tank; S5. The first supernatant is aerated and stirred, and then introduced into the primary SAO3 ozone for catalytic oxidation to obtain the second treated wastewater, and then flows to the biochemical treatment system to be biochemically treated with activated sludge to obtain the third treated wastewater, and then flows to the second sedimentation tank to separate the mud and water to obtain the second supernatant and the lower sludge; the second supernatant is transferred to the second transfer water tank for temporary storage, and the lower sludge is discharged to the sludge tank; S6. The second supernatant is aerated and stirred and passed into the secondary SAO3 ozone catalytic oxidation to obtain the fourth treated wastewater, which meets the sewage treatment plant pipe standard and is then discharged into the buffer tank; S7. The treated and purified wastewater is buffered in the discharge pool and eventually discharged evenly in compliance with the standards. The sludge in the sludge pool is concentrated by gravity and then pumped into the plate filter press for filtration and dehydration. The filtrate is returned to the wastewater mixing reaction pool and the dehydrated sludge is packaged and outsourced for disposal.

2. The method according to claim 1, characterized in that The wastewater in S1 is one or more of high-salt wastewater, high-COD wastewater, high-ammonia nitrogen wastewater, strong acid and strong alkali wastewater, electroplating wastewater containing heavy metals, and oily wastewater; and is stored according to the COD, ammonia nitrogen index range, acidity and alkalinity of the wastewater, and whether it contains oil.

3. The method according to claim 1, characterized in that The COD concentration of the mixed wastewater in S2 is between 3000 and 8000 mg / L, the ammonia nitrogen concentration is between 500 and 2000 mg / L, and the petroleum concentration is between 0 and 100 mg / L.

4. The method according to claim 1, characterized in that The wastewater in S2 is adjusted to a pH value of 1 to 6; the regulator is sulfuric acid.

5. The method according to claim 1, characterized in that The iron-carbon micro-electrolysis treatment in S3 is carried out using an FCM-IV iron-carbon micro-electrolysis device, and the wastewater reaction residence time is 1 to 10 hours; The FCM-IV iron-carbon micro-electrolysis device consists of a reactor, water distribution, gas distribution, backwash gas distribution, pebble filler and iron-carbon micro-electrolysis filler. The pebble filling specifications are φ32-16mm, φ16-8mm, and φ8-4mm, and the filling height of each specification is 30cm. The specifications are arranged from large to small from the bottom to the top. The upper part of the pebbles is filled with iron-carbon micro-electrolysis filler, and the filling height is 2 to 4m.

6. The method according to claim 1, characterized in that In said S4, the pH value is adjusted to 7-11; Delayed aeration time is 1-3h; The dosage of PAC is 100-1000 mg / L, and the dosage of PAM is 5-20 mg / L.

7. The method according to claim 1, characterized in that The first-level SAO3 ozone catalytic oxidation in S5 has a wastewater reaction residence time of 1 to 10 hours, and an ozone dosage of 100 to 2000 mg / L; The first-stage SAO3 ozone catalytic oxidation device consists of an ozone catalytic oxidation reactor, water distribution, gas distribution, backwashing, pebbles and ozone-specific catalysts. The pebbles are filled with specifications of φ32-16mm, φ16-8mm, and φ8-4mm, and the filling height of each specification is 30cm. The specifications are arranged from large to small from the bottom to the top. The upper part of the pebbles is filled with SAO3 ozone catalyst filler, and the filling height is 2 to 4m.

8. The method according to claim 1, characterized in that The biochemical treatment system in S5 sequentially performs treatment in an anaerobic tank, an anoxic tank, and an aerobic tank.

9. The method according to claim 1, characterized in that: The residence time of the secondary SAO3 ozone catalytic oxidation reaction in the S6 is 0.5 to 5 hours, and the ozone dosage is 50 to 200 mg / L.

10. The method according to claim 1, characterized in that The discharge pool buffer residence time in S7 is 2 to 4 hours; the sludge filter pressing needs to condition the sludge before the filtration, and the conditioning method can be adding PAM for stirring, and the PAM dosage is 10 to 100 mg / L.

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