Device and method for treating sewage by using wastewater produced by dry strength agent

Abstract

The present invention provides a device for treating sewage using dry strength agent production wastewater, comprising a sewage regulating tank, a sewage coagulation tank, a coagulation sedimentation tank and a biochemical treatment tank connected in sequence through pipelines, a sewage pump is arranged between the sewage regulating tank and the sewage coagulation tank, the sewage coagulation tank comprises a first coagulation tank, a second coagulation tank and a third coagulation tank connected in sequence, the first coagulation tank is connected to an acid-base tank, the second coagulation tank is connected to a polyaluminium chloride tank, and the third coagulation tank is connected to a dry strength agent production wastewater tank. The present invention also provides a method for treating sewage, through the device and method of the present invention, the dry strength agent production wastewater can be effectively used to flocculate and purify sewage, which has high commercial value and promotion value.

Description

Technical Field

[0001] The invention relates to the field of sewage treatment, and in particular to a device and method for treating sewage by utilizing dry strength agent production wastewater. Background Art

[0002] Dry strength agent is an important chemical used in the paper industry to increase the strength of paper. It is a kind of papermaking auxiliary agent. It is formed by the polymerization reaction of acrylamide and a variety of small materials. Many water-soluble polymers that can form hydrogen bonds with fibers can become dry strength agents. Dry strength agents are usually used to compensate for the decrease in paper strength caused by the addition of fillers or low-grade fibers (such as recycled fibers). Polyacrylamide (cpolyacrylamids), referred to as PAM, is a common dry strength agent. It is a linear polymer and one of the most widely used varieties of water-soluble polymer compounds. Polyacrylamide and other biological substances can be used as effective flocculants, thickeners, paper strengtheners, and liquid drag reducers, etc. They are widely used in water treatment, papermaking, petroleum, coal, mining, geology, textiles, construction and other work departments.

[0003] The main component of papermaking dry strength agent is amphoteric polyacrylamide. The purpose of adding dry strength agent is to flocculate and retain paper fibers and promote pulp dehydration. After the amphoteric polyacrylamide molecules are combined with the pulp, the retention rate of fine components is increased through flocculation, which promotes pulp dehydration. The viscosity of dry strength agent is relatively large, about 8000-15000cp. The reactor, storage tank and storage barrel of dry strength agent need to be cleaned to produce a lot of wastewater. The viscosity of these wastewaters is high, COD is as high as 7000mg / L or more, and the total nitrogen is about 700mg / L. If these sewages are sent to the sewage treatment station for biochemical treatment, there will be great treatment pressure on the sewage station and relatively high treatment costs. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a device for treating sewage by using wastewater produced by dry strength agent, so as to solve the problem that the wastewater produced by dry strength agent is difficult to treat and requires a large cost.

[0005] In order to solve the above problems, the present invention provides a device for treating sewage using dry strength agent production wastewater, comprising a sewage regulating tank, a sewage coagulation tank, a coagulation sedimentation tank and a biochemical treatment tank which are connected in sequence through pipelines, a sewage pump is arranged between the sewage regulating tank and the coagulation tank, the sewage coagulation tank comprises a first coagulation tank, a second coagulation tank and a third coagulation tank which are connected in sequence, the first coagulation tank is connected to an acid-base tank, the second coagulation tank is connected to a polyaluminum chloride tank, and the third coagulation tank is connected to a dry strength agent production wastewater tank.

[0006] Through the design of the above-mentioned device of the present invention, the sewage can be effectively purified through the first coagulation tank, the second coagulation tank and the third coagulation tank. The first coagulation tank adjusts the pH of the sewage, and the second coagulation tank and the third coagulation tank flocculate the particles in the sewage. The third flocculation tank itself passes the dry strength agent production wastewater, which plays the role of treating waste with waste. The coagulation sedimentation tank is used to precipitate the sewage after coagulation in the above three coagulation tanks, and the biochemical treatment tank can perform biochemical regulation on the sewage again. Through this device, the sewage can be effectively flocculated and purified.

[0007] As a preferred solution, the biochemical treatment pool includes an anaerobic pool, an A pool and an O pool which are connected in sequence. The anaerobic pool and the A / O pool can further biochemically treat the supernatant after precipitation to further reduce COD, ammonia nitrogen and total nitrogen in the water.

[0008] As a preferred solution, metering pumps are provided between the first coagulation tank and the acid and alkali tank, between the second coagulation tank and the polyaluminium chloride tank, and between the third coagulation tank and the dry strength agent production wastewater tank. The metering pumps can control the liquids in the acid and alkali tank, the polyaluminium chloride tank, and the dry strength agent production wastewater tank to flow into the coagulation tanks under the premise of controlling the dosage.

[0009] As a preferred solution, the acid and alkali tank is arranged outside the first coagulation tank, the polyaluminium chloride tank is arranged outside the second coagulation tank, and the dry strength agent production wastewater tank is arranged outside the third coagulation tank. The above tanks are arranged outside the coagulation tanks to facilitate the replenishment of the raw materials inside the tanks and do not occupy the space inside the coagulation tanks.

[0010] As a preferred solution, the bottom of the coagulation sedimentation tank is a conical bottom, and a mud discharge pipe is arranged on the conical bottom, and the mud discharge pipe is connected to a mud discharge pump arranged outside the coagulation sedimentation tank, and an openable / closable overflow port is arranged in the coagulation sedimentation tank, and the overflow port is arranged at the upper part of the coagulation sedimentation tank. Through the design of the conical bottom, the sewage can be effectively and efficiently deposited at the bottom of the conical bottom, so that the mud discharge pump drives the mud discharge pipe to extract the sludge at the bottom of the conical bottom. The overflow port is arranged at the upper part of the conical bottom, and the upper clear liquid can also be efficiently passed into the biochemical treatment tank for treatment.

[0011] As a preferred solution, the first coagulation tank, the second coagulation tank and the third coagulation tank are all provided with stirring devices, and the first coagulation tank, the second coagulation tank and the third coagulation tank are also provided with openable / closable flow ports. The design of the stirring device can speed up the reaction inside the coagulation tank, and after the reaction is completed, the flow port can be opened to pass the sewage into the next coagulation tank for treatment, which is very convenient.

[0012] Another technical problem to be solved by the present invention is to provide a method for treating sewage using the above device to solve the problem of high cost of treating wastewater produced by dry strength agent using conventional methods.

[0013] In order to solve the above problems, the present invention provides a method for treating sewage using the device, comprising the following steps:

[0014] S1: The sewage to be treated is introduced into the sewage regulating tank, and the sewage is introduced into the first coagulation tank through the sewage pump to adjust the pH of the sewage in the first coagulation tank;

[0015] S2: The sewage treated by S1 is further introduced into the second coagulation tank, and polyaluminium chloride is continuously injected into the second coagulation tank to preliminarily purify the sewage;

[0016] S3: The wastewater treated by S2 is introduced into the third coagulation tank, and the wastewater produced by the dry strength agent is introduced to further flocculate the wastewater; the wastewater produced by the dry strength agent includes (C3H5NO) n ·(C8H 15 NO2) m and one or more of acrylamide, cationic monomer DMC, DMAM sulfate, n,n-dimethylacrylamide, sodium methacrylic sulfonate, citric acid and itaconic acid.

[0017] S4: The sewage treated in S3 is introduced into a coagulation sedimentation tank for sedimentation. After sedimentation, the upper liquid is introduced into a biochemical treatment tank for anaerobic and aerobic treatment to complete the sewage treatment.

[0018] As a preferred solution, in step S1, the pH of the sewage in the first coagulation tank is 7-8.5.

[0019] As a preferred solution, in step S2, the mass concentration of the polyaluminium chloride is 1-4%, and the amount added is 3-10% of the weight of the sewage; in step S3, the amount of the dry strength agent production wastewater added is 0.05-0.15% of the weight of the sewage.

[0020] As a preferred solution, the step S4 further includes the operation of discharging the sludge at the bottom of the coagulation sedimentation tank from the coagulation sedimentation tank through a sludge discharge pump.

[0021] The present invention utilizes the polymer characteristics of dry strength agent wastewater, and its properties are similar to those of flocculant PAM. The flocculation mechanism of papermaking dry strength agent includes: the polyacrylamide dry strength agent with cationic and anionic charges forms interpenetrating aggregates with fine fibers, fillers, etc. in the slurry through bridging and electrostatic adsorption. Such aggregates have a certain network structure, and there are many internal action points, which are relatively tightly combined with each other, with a large action force, good shear resistance, not easy to be destroyed, and good flocculation effect. This study uses dry strength agent wastewater as a flocculant and achieves a relatively good flocculation effect. It not only consumes these dry strength agent wastewater, but also can flocculate and precipitate other sewage that needs to be treated in the sewage station, indicating that the dry strength agent wastewater can fully meet the requirements of sewage treatment flocculants, which not only solves the problem of dry strength agent production wastewater, but also reduces the cost of sewage treatment, and achieves the effect of turning waste into treasure. This technology has great economic and social value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the device of the present invention;

[0023] Figure 2 The types of components of the dry strength agent wastewater of the present invention and the chemical formulas thereof;

[0024] Description of reference numerals:

[0025] 1. Sewage regulating tank; 2. Sewage pump; 3. Sewage coagulation tank; 31. First coagulation tank; 32. Second coagulation tank; 33. Third coagulation tank; 4. Acid and alkali tank; 5. Polyaluminium chloride tank; 6. Dry strength agent production wastewater tank; 7. Metering pump; 8. Mud discharge pipe; 9. Conical bottom; 10. Coagulation sedimentation tank; 11. Mud discharge pump; 12. Biochemical treatment tank; 121. Anaerobic tank; 122. A tank; 123. O tank; 13. Stirring device; 14. Flow port; 15. Overflow port. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0027] Embodiment 1:

[0028] This embodiment provides the structure of a device for treating sewage using dry strength agent production wastewater:

[0029] like Figure 1 , Figure 2 As shown, Figure 1 It is a structural schematic diagram of the present invention, Figure 2 The chemical formula of the dry strength agent wastewater of the present invention. In the present invention, the dry strength agent wastewater refers to the wastewater generated in the process of producing the dry strength agent. The wastewater components include water and the attached drawings of the specification. Figure 2The present invention comprises a sewage regulating tank 1, a sewage coagulation tank 3, a coagulation sedimentation tank 10 and a biochemical treatment tank 12 which are sequentially connected through pipelines, and the biochemical treatment tank 12 comprises an anaerobic tank 121, an A tank 122 and an O tank 123 which are sequentially connected;

[0030] A sewage pump 2 is arranged between the sewage regulating tank 1 and the sewage coagulation tank 3, and the sewage pump 2 is used to pump sewage into the coagulation tank. The sewage coagulation tank 3 includes a first coagulation tank 31, a second coagulation tank 32 and a third coagulation tank 33 which are connected in sequence. The first coagulation tank 31 is connected to an acid-base tank 4, the second coagulation tank 32 is connected to a polyaluminium chloride tank 5, and the third coagulation tank 33 is connected to a dry strength agent production wastewater tank 6. The acid-base tank 4 is arranged outside the first coagulation tank 31, the polyaluminium chloride tank 5 is arranged outside the second coagulation tank 32, the dry strength agent production wastewater tank 6 is arranged outside the third coagulation tank 33, and the first coagulation tank 31 is connected to the third coagulation tank 33. A metering pump 7 is provided between the coagulation tank 31 and the acid-base tank 4, between the second coagulation tank 32 and the polyaluminium chloride tank 5, and between the third coagulation tank 33 and the dry strength agent production wastewater tank 6. The metering pump 7 is used to quantitatively extract the liquid in the tank to each coagulation tank; a stirring device 13 is provided inside the first coagulation tank 31, the second coagulation tank 32 and the third coagulation tank 33, and an openable / closable flow port 14 is also provided inside the first coagulation tank 31, the second coagulation tank 32 and the third coagulation tank 33. By opening the flow port 14, the sewage treated in the previous coagulation tank can be passed into the next coagulation tank. Generally speaking, the flow port 14 is provided at the bottom of the coagulation tank;

[0031] The bottom of the coagulation sedimentation tank 10 is a conical bottom 9, and a mud discharge pipe 8 is arranged on the conical bottom 9, and the mud discharge pipe 8 is connected to a mud discharge pump 11 arranged outside the coagulation sedimentation tank 10; an openable / closable overflow port 15 is arranged in the coagulation sedimentation tank 10, and the overflow port 15 is arranged at the upper part of the coagulation sedimentation tank 10. After the sedimentation of the coagulation sedimentation tank 10 is completed, the precipitate after the sewage flocculation falls into the conical bottom 9, and by opening the overflow port 15, the supernatant can be passed into the next biochemical treatment tank 12 for biochemical treatment;

[0032] Embodiment 2:

[0033] This embodiment provides a method for treating sewage using dry strength agent production wastewater, comprising the following steps:

[0034] S1: The sewage to be treated is introduced into the sewage regulating tank 1, and the sewage is introduced into the first coagulation tank 31 through the sewage pump 2, and the pH of the sewage in the first coagulation tank 31 is adjusted. If the pH of the sewage is acidic, an appropriate amount of 30% liquid alkali is introduced to adjust the pH. If the pH of the sewage is alkaline, 15% hydrochloric acid is introduced to adjust the pH, and the pH of the sewage in the first coagulation tank 31 is adjusted to 7-8.5;

[0035] S2: The sewage treated by S1 is further introduced into the second coagulation tank 32, and polyaluminium chloride is continuously injected into the second coagulation tank 32 to preliminarily purify the sewage, and the mass concentration of the polyaluminium chloride is 1-4%, and the addition amount is 3-10% of the weight of the sewage;

[0036] S3: The wastewater treated by S2 is introduced into the third coagulation tank 33, and the wastewater produced by the dry strength agent is introduced to further flocculate the wastewater. The amount of the wastewater produced by the dry strength agent is 0.05-0.15% of the weight of the wastewater. The wastewater produced by the dry strength agent includes (C3H5NO) n ·(C8H 15 NO2) m and one or more of acrylamide, cationic monomer DMC, DMAM sulfate, n,n-dimethylacrylamide, sodium methacrylic sulfonate, citric acid and itaconic acid:

[0037] S4: The sewage treated by S3 is introduced into the coagulation sedimentation tank 10 for sedimentation. After sedimentation, the upper liquid is introduced into the biochemical treatment tank 12 for anaerobic and aerobic treatment. The sludge at the bottom of the coagulation sedimentation tank 10 is discharged from the coagulation sedimentation tank 10 through the sludge pump 11 to complete the treatment of the sewage.

[0038] Embodiment 3:

[0039] This embodiment provides a specific example, using the device of embodiment 1 and the method of embodiment 2 to treat sewage using dry strength agent production wastewater, the specific method is as follows:

[0040] S1: The sewage to be treated is introduced into the sewage regulating tank 1, wherein the pH of the sewage is 4.28, the COD content is 9218 mg / L, the NH3-N content is 280.28 mg / L, the TN content is 430 mg / L, the TP content is 0.63 mg / L, and the conductivity is 2110 S / m. The above sewage is introduced into the first coagulation tank 31 through the sewage pump 2, and an appropriate amount of 30% liquid alkali is introduced to adjust the pH, and the pH of the sewage in the first coagulation tank 31 is adjusted to 7-8.5;

[0041] S2: The sewage treated by S1 is further introduced into the second coagulation tank 32, and polyaluminium chloride is continuously injected into the second coagulation tank 32 to preliminarily purify the sewage, and the mass concentration of the polyaluminium chloride is 1-4%, and the addition amount is 3-10% of the weight of the sewage;

[0042] S3: The wastewater treated by S2 is introduced into the third coagulation tank 33, and the dry strength agent production wastewater is introduced into the dry strength agent production wastewater tank 6 in advance, wherein the dry strength agent pH is 6.43, the COD content is 7383 mg / L, the NH3-N content is 27.50 mg / L, the TN content is 886.40 mg / L, the TP content is 0.02 mg / L, and the conductivity is 1670 S / m, and the dry strength agent production wastewater is introduced to further flocculate the wastewater, and the addition amount of the dry strength agent production wastewater is 0.05-0.15% of the weight of the wastewater; the dry strength agent production wastewater includes (C3H5NO) n ·(C8H 15 NO2) m and one or more of acrylamide, cationic monomer DMC, DMAM sulfate, n,n-dimethylacrylamide, sodium methacrylic sulfonate, citric acid and itaconic acid:

[0043] S4: The sewage treated by S3 is introduced into the coagulation sedimentation tank 10 for sedimentation. After sedimentation, the upper liquid is introduced into the biochemical treatment tank 12 for anaerobic and aerobic treatment. The sludge at the bottom of the coagulation sedimentation tank 10 is discharged from the coagulation sedimentation tank 10 through the sludge pump 11 to complete the treatment of the sewage. The treated sewage obtained has a pH value of 7.33, a COD content of 507.2 mg / L, an NH3-N content of 47.3 mg / L, a TN content of 67.6 mg / L, a TP content of 0.51 mg / L, and a conductivity of 1312 S / m.

[0044] It can be found from the treatment of Example 3 that the sewage treated by the device and method of the present invention is effectively purified, and the dry strength agent production wastewater that needs to be treated itself is also utilized in the treatment. Finally, the sewage of the two is comprehensively purified, and the purification effect is also very excellent.

[0045] The principle of the present invention is that the main component of the papermaking dry strength agent is amphoteric polyacrylamide, which is a water-soluble polymer with anionic and cationic groups on the polymer molecular chain with acrylamide as the main monomer. Its molecular structure is a huge linear molecule, each macromolecule is composed of many chain links, and the chain links are covalently bonded. The chain links on the molecule have a very strong adsorption effect on the colloidal particles in the water, and the flocculation effect is excellent. The mechanism of its flocculation is that in sewage treatment, suspended pollutants are mainly negatively charged. The dry strength agent is amphoteric polyacrylamide, and the cationic groups it carries are positively charged. During flocculation, it has the functions of electrical neutralization, bridging, and netting, and can be better adsorbed on the surfaces of multiple particles, so that the suspended matter can be more effectively settled. On the other hand, the sewage system is relatively complex. In addition to the suspended matter carrying negative charges, there are also many other positively charged ions, particles, etc. These counterions will inevitably have a negative impact on the flocculation effect of the polymer. When the dry strength agent is amphoteric polyacrylamide and is used as a flocculant, the anionic groups on the molecular chain can eliminate the negative effects of these counterions, so that the positive charge can be effectively adsorbed on the surface of the pollutant particles. At the same time, the attraction of different ionic groups between polymer molecules strengthens the net capture effect, making the adsorbed particles more likely to aggregate and settle. Therefore, compared with anionic and cationic polyacrylamide, dry strength agent has better flocculation effect. Dry strength agent production wastewater can be used as a sewage treatment flocculant to produce a good flocculation effect, thereby purifying sewage, reducing COD, ammonia nitrogen and total nitrogen in sewage, and turning waste into treasure.

[0046] Although the disclosure is disclosed as above, the protection scope of the disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the disclosure, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A method for treating sewage using a device for treating sewage from wastewater produced by dry strength agent production, characterized in that: The following steps are involved: S1: introducing the sewage to be treated into the sewage regulating tank (1), introducing the sewage into the first coagulation tank (31) through the sewage pump (2), and adjusting the pH of the sewage in the first coagulation tank (31); S2: the sewage treated in S1 is further introduced into the second coagulation tank (32), and polyaluminium chloride is continuously injected into the second coagulation tank (32) to preliminarily purify the sewage; S3: introducing the wastewater treated by S2 into a third coagulation tank (33), and introducing wastewater produced by dry strength agent into the wastewater for further flocculation treatment; the wastewater produced by dry strength agent comprises (C3H5NO)n·(C8H15NO2)m and one or more of acrylamide, cationic monomer DMC, DMAM sulfate, n,n-dimethylacrylamide, sodium methyl methacrylate sulfonate, citric acid and itaconic acid; S4: introducing the sewage treated in S3 into a coagulation sedimentation tank (10) for sedimentation, and introducing the upper liquid into a biochemical treatment tank (12) for anaerobic and aerobic treatment after sedimentation, thereby completing the sewage treatment; The device comprises a sewage regulating tank (1), a sewage coagulation tank (3), a coagulation sedimentation tank (10) and a biochemical treatment tank (12) which are sequentially connected through pipelines, a sewage pump (2) is arranged between the sewage regulating tank (1) and the sewage coagulation tank (3), the sewage coagulation tank (3) comprises a first coagulation tank (31), a second coagulation tank (32) and a third coagulation tank (33) which are sequentially connected, the first coagulation tank (31) is connected to an acid-base tank (4), the second coagulation tank (32) is connected to a polyaluminium chloride tank (5), and the third coagulation tank (33) is connected to a dry strength agent production wastewater tank (6); The biochemical treatment pool (12) comprises an anaerobic pool (121), an A pool (122) and an O pool (123) which are connected in sequence; A metering pump (7) is provided between the first coagulation tank (31) and the acid-base tank (4), between the second coagulation tank (32) and the polyaluminium chloride tank (5), and between the third coagulation tank (33) and the dry strength agent production wastewater tank (6); The acid-base tank (4) is arranged outside the first coagulation tank (31), the polyaluminium chloride tank (5) is arranged outside the second coagulation tank (32), and the dry strength agent production wastewater tank (6) is arranged outside the third coagulation tank (33); The bottom of the coagulation sedimentation tank (10) is a conical bottom (9), and a mud discharge pipe (8) is arranged on the conical bottom (9), and the mud discharge pipe (8) is connected to a mud discharge pump (11) arranged outside the coagulation sedimentation tank (10); an openable / closable overflow port (15) is arranged in the coagulation sedimentation tank (10), and the overflow port (15) is arranged at the upper part of the coagulation sedimentation tank (10).

2. The method for treating sewage according to claim 1, characterized in that: The first coagulation tank (31), the second coagulation tank (32) and the third coagulation tank (33) are each provided with a stirring device (13), and the first coagulation tank (31), the second coagulation tank (32) and the third coagulation tank (33) are also provided with an openable / closable flow port (14).

3. The method for treating sewage according to claim 1, characterized in that: In the step S1, the pH of the sewage in the first coagulation tank (31) is 7-8.

5.

4. The method for treating sewage according to claim 3, characterized in that: In the step S2, the mass concentration of the polyaluminium chloride is 1-4%, and the addition amount is 3-10% of the weight of the sewage; in the step S3, the addition amount of the dry strength agent production wastewater is 0.05-0.15% of the weight of the sewage.

5. The method for treating sewage according to claim 3, characterized in that: The step S4 also includes the operation of discharging the sludge at the bottom of the coagulation sedimentation tank (10) from the coagulation sedimentation tank (10) via a sludge discharge pump (11).

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