Equipment and method capable of realizing segmented treatment of zero discharge and comprehensive utilization of wastewater for papermaking enterprises

Abstract

The invention relates to the technical field of comprehensive treatment in pulping and papermaking industries, and discloses equipment capable of treating wastewater in a segmented manner, realizing zero discharge and comprehensively utilizing wastewater for papermaking enterprises, which comprises a sewage treatment box, the sewage treatment mechanism comprises two rotating rods I, four bead wheels, two conveying belts, a plurality of screen mesh integrated filter plates, a water inlet pipe, two limiting plates I, a limiting plate II and a material guide plate. Different types of pollutants can be removed in a targeted manner based on a three-stage treatment mode, so that the effluent index meets the recycling requirement, the purification effect is improved, filter material blockage can be avoided through real-time cleaning, the shutdown maintenance frequency is reduced, soluble salt or settleable floc can be generated through chemical reaction, no harmful by-product is generated, the environmental protection requirement is met, and the method is suitable for industrial production. Fiber impurities are recycled, wastewater is circulated in a closed manner, and the water resource cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of comprehensive wastewater treatment technology in the pulp and paper industry, and in particular to a device and method for paper mills to treat wastewater in stages for zero discharge and comprehensive utilization. Background Technology

[0002] Currently, wastewater from the pulp and paper industry has a complex composition, containing a large amount of suspended solids (fiber fragments, silt), colloidal particles (lignin colloids, CaCO3 fillers), dissolved organic matter (color substances, small molecule COD), and acid and alkali pollutants, making it difficult to treat.

[0003] Chinese invention patent CN101096825A discloses a segmented wastewater treatment and zero-discharge, comprehensive utilization process for clean pulp production. Its key feature is the segmented treatment of wastewater from the pulping process. Through pretreatment, mesh filtration, microfiltration (MF), ultrafiltration (UF), and nanofiltration (NF) membrane technologies, washing wastewater, cooking black (red) liquor, intermediate stage wastewater, and bleaching wastewater are purified in stages. During purification, the sieving effect is applied to selectively extract and separate lignin and other organic compounds from solids, which are then further processed into economically valuable new products. The purified wastewater becomes clean water, which is recycled within the same production stage without external discharge. This invention can replace traditional alkali recovery and three-stage biological treatment methods, achieving complete elimination of pollution and zero discharge, energy and water conservation, and comprehensive utilization to improve enterprise economic benefits. It is an essential path for clean production in the pulp and paper industry.

[0004] Regarding the aforementioned technologies, the inventors believe that the following defects exist: traditional alkali recovery processes involve huge investments and complex procedures, and emit harmful gases such as hydrogen sulfide and sulfur dioxide, causing air pollution; the three-stage biological treatment method is passive and inefficient, unable to achieve complete wastewater purification and zero discharge; some treatment equipment lacks targeted segmented design, filter media is prone to clogging, purification efficiency is unstable, and a "treatment-recovery-reuse" closed loop is not formed, resulting in serious waste of water resources and ineffective recovery of pollutants. Summary of the Invention

[0005] To address the technical problems mentioned in the background section, this invention provides a device and method for paper manufacturing enterprises to treat wastewater in stages, achieve zero discharge, and comprehensively utilize it.

[0006] The present invention is achieved by the following technical solution: a device for papermaking enterprises that can treat wastewater in sections, achieve zero discharge, and comprehensively utilize it, comprising: a wastewater treatment tank, wherein the wastewater treatment tank is provided with a wastewater treatment mechanism, the wastewater treatment mechanism including two rotating rods, four ball wheels, two conveyor belts, multiple integrated screen grid filter plates, a water inlet pipe, two limiting plates, two limiting plates, and a guide plate; the two rotating rods are symmetrically rotated and installed on the inner walls of both sides of the wastewater treatment tank; the four ball wheels are fixedly sleeved on the two rotating rods in pairs; the two conveyor belts are sleeved on the corresponding two ball wheels and adapted to the ball wheels; and the multiple integrated screen grid filter plates are equidistantly installed on the two conveyor belts. Two limiting plates are symmetrically installed in the sewage treatment tank, one in front of the other. The two limiting plates are located on one side of the two conveyor belts respectively. The second limiting plate is installed on the two limiting plates. The water inlet pipe is installed on the top of the sewage treatment tank. The bottom end of the water inlet pipe extends into the sewage treatment tank and is located between the two limiting plates. The wastewater treatment tank has a discharge port on one side of its outer wall, and a guide plate is installed on the discharge port. A collection box is installed on one side of the wastewater treatment tank, and the collection box is compatible with the discharge port and the guide plate.

[0007] As a further improvement to the above solution, the wastewater treatment tank is equipped with a filter assembly, which includes a mounting frame 1 installed inside the wastewater treatment tank. A partition plate 1 is installed on the bottom inner wall of the mounting frame 1, and a guide block 1 is installed on the top of the partition plate 1. The space inside the mounting frame 1 is divided into a left space and a right space by the partition plate 1. Both the left space and the right space are located below the integrated screen grid filter plate. Filter plate 1 and filter plate 2 are installed in the left space and the right space, respectively.

[0008] As a further improvement to the above solution, the sewage treatment tank is equipped with a cleaning component, which includes a rotating rod II. The rotating rod II is installed inside the sewage treatment tank and is located between two adjacent integrated screen grid filter plates. The cleaning brush is fixedly sleeved on the rotating rod II and is in contact with the integrated screen grid filter plate. A connecting pipe is installed inside the sewage treatment tank, and multiple nozzles I are connected to the outer wall of the connecting pipe. The connecting pipe is located between the rotating rod II.

[0009] As a further improvement to the above solution, the sewage treatment tank is equipped with a drive assembly, which includes a water pump. The water pump is installed on one outer wall of the sewage treatment tank. A water pump inlet is equipped with a water pump pipe, and a water pump outlet is equipped with a water pump outlet. One end of the water pump outlet extends into the sewage treatment tank and is connected to a connecting pipe. A motor is installed on one outer wall of the sewage treatment tank. One end of a rotating rod extends to the outside of the sewage treatment tank and is fixedly connected to the output shaft of the motor. A main gear is fixedly sleeved on the rotating rod, and one end of the rotating rod extends to the outside of the sewage treatment tank and is fixedly sleeved with a driven gear. The driven gear meshes with the main gear.

[0010] As a further improvement to the above solution, the sewage treatment tank is provided with a connecting water guiding component, which includes a partition plate two. The partition plate two is installed inside the sewage treatment tank, and the space inside the sewage treatment tank is divided into an upper space and a lower space by the partition plate two. The partition plate two is located below the bottom of the mounting frame one. The material guiding block two is installed on the top of the partition plate two. The sewage treatment tank and the material guiding block two share the same material guiding block three. A connecting pipe is installed on one outer wall of the sewage treatment tank. The two ends of the connecting pipe extend into the upper space and the lower space, respectively. Two triangular inclined blocks are symmetrically installed on the material guiding block two. The end of the connecting pipe extending into the upper space is located between the two triangular inclined blocks.

[0011] As a further improvement to the above solution, a partition plate three is installed in the lower space, which is divided into a stirring space and an aeration space by the partition plate three. A stirring assembly is provided in the stirring space. The stirring assembly includes two rotating rods three, which are symmetrically installed in the stirring space. Multiple stirring rods are fixedly installed on each of the two rotating rods three. One end of each of the two rotating rods three extends to one side of the sewage treatment tank and is fixedly fitted with a rotating gear three. A rotating gear one is fixedly installed on one end of the rotating rod three, and a rotating gear two is fixedly installed on one end of the rotating rod two. The rotating gear one and the rotating gear two are fitted with the same toothed belt.

[0012] As a further improvement to the above solution, the partition plate three has an opening, the aeration space is equipped with an aeration assembly, the aeration assembly includes an air pipe, the air pipe is installed in the aeration space, the outer wall of the air pipe is connected to and installed with multiple nozzles two, one side of the outer wall of the sewage treatment tank is equipped with an air pump, the exhaust port of the air pump is connected to and installed with an exhaust pipe, the exhaust pipe is equipped with a one-way valve, one end of the exhaust pipe extends into the sewage treatment tank and is connected to the air pipe.

[0013] As a further improvement to the above solution, an installation frame two is installed in the aeration space, and a guide block four is installed on the top of the installation frame two. The outer wall of the guide block four is attached to the inner wall of the aeration space. A bamboo charcoal filter plate and an activated carbon filter plate are installed in the installation frame two. A water outlet pipe is installed on one side of the outer wall of the sewage treatment tank, and one end of the water outlet pipe extends into the aeration space. A controller is installed on one side of the outer wall of the sewage treatment tank.

[0014] As a further improvement to the above solution, a dosing pipe is installed on one outer wall of the wastewater treatment tank. One end of the dosing pipe extends into the stirring space, through which pH adjuster, coagulant, flocculant, and coagulant aid are added. The effects of adding these reagents in sequence are as follows: (1) pH adjuster: Adjusts the pH value of the wastewater to the optimal reaction range for subsequent coagulation and flocculation, neutralizes excess acid and alkali in the wastewater, reduces the damage of acid and alkali to subsequent agents, promotes the dissolution or precipitation of some acidic and alkaline pollutants, and assists in subsequent removal. The reaction formula is as follows: H2SO4 + 2NaOH → Na2SO4 + 2H2O, producing soluble salts without secondary pollution; Ca (OH)2 + H2SO4 → CaSO4↓ + 2H2O, producing slightly soluble calcium sulfate, which can settle with the flocs and help remove suspended solids; H2SO4 ionization produces H + Preferred to be OH - reaction (H) + +OH - →H2O), consumes excess OH in wastewater - This shifts the Ca(OH)2 dissolution equilibrium to the right, resulting in the continuous release of Ca. 2+ ; When Ca 2+ Concentration and SO 2- The product of concentrations ≥ the solubility product of CaSO4 (Ksp = 9.1 × 10⁻⁶). -6 At 25℃, crystallization and precipitation occur: Ca 2 + SO4 2- →CaSO4(s); The initially generated CaSO4 consists of fine crystal nuclei (particle size <1μm). By controlling the stirring intensity (80 r / min) and residence time (20~25 min), the crystal nuclei gradually grow into needle-like or plate-like crystals (particle size 5~10μm), forming "floc nuclei". Ca(OH)2(s, lime milk) + H2SO4(aq) → CaSO4(s, crystal form II) + 2H2O(I) (Crystal form II is stable calcium sulfate dihydrate, with the best sedimentation performance).

[0015] (2) Coagulant: Removes fine suspended solids and colloidal particles from wastewater, such as fiber fragments, filler CaCO3, and lignin colloids, reduces turbidity, adsorbs some dissolved organic matter, such as color substances and small molecule COD, reduces COD and color, provides "micro floc nuclei" for subsequent flocculation, and enhances floc growth. The reaction formula is as follows: Colloid) + 3H2SO4 (Al(OH)3; Aluminum sulfate completely ionizes in aqueous solution to form Al. 3+ and SO4 2- ; Al2(SO4)3(aq)→2Al 3+ (aq) + 3SO4 2- (aq), SO4 2- As inert ions, they do not participate in subsequent reactions, but only provide an electrolyte environment and compress the colloidal double layer in wastewater (assisting in destabilization). The core reaction is carried out by Al. 3+ leading; Al 3+ The hydrolysis is a stepwise reversible reaction, controlled by pH and temperature, ultimately producing Al(OH)3 colloid. The steps of the reaction are as follows: Step 1 (Primary Hydrolysis): Al 3+ + H2 2+ (aq) + H + (Equilibrium constant K1 = 1.4 × 10 at 25℃) -5 ), forming a positively charged mononuclear hydroxyl complex; Step 2 (Intermediate Hydrolysis): [Al(OH)] 2+ + H2 2] + (aq) + H + (K2=1.0×10) -6 Further hydroxylation weakens the positive charge; Step 3 (Advanced Hydrolysis): [Al(OH)2] + + H2 3(colloid) + H + (K3=8.0×10) -8 This generates amorphous Al(OH)3 colloids with a weak positive charge on the surface. Synergistic polymerization: Some mononuclear hydroxyl complexes form polynuclear complexes (such as [Al2(OH)2)) through "hydroxyl-bridged polymerization". 4+ [Al3(OH)6] 3+ These polynuclear complexes are the core precursors for the formation of "micro-flocs"; Excessive HCO3 in wastewater3- It will consume the H generated by hydrolysis + (HCO3) - + H + →CO2↑+ H2O), which pushes the hydrolysis equilibrium to the right and promotes the formation of a large amount of Al(OH)3 colloid; Al(OH)3 colloids have a positively charged surface. They are electrostatically attracted to negatively charged pollutants in papermaking wastewater, neutralizing the surface charge and causing the colloids to lose their stability. The amorphous structure of Al(OH)3 colloid has a large specific surface area, and the surface hydroxyl groups (-OH) can adsorb soluble color substances and small molecule COD in wastewater through hydrogen bonds and van der Waals forces. The adsorbed pollutant particles combine with Al(OH)3 colloids to form "micro flocs" with a diameter of 1~5μm, providing attachment points for the subsequent bridging effect of flocculant (PAM) and ensuring the rapid generation of large-volume flocs; Al(OH)3 colloid is stable at pH 6.5–7.5 and will not undergo further hydrolysis to form AlO2. - (When pH>8) or redissolve (when pH<5); The generated flocs have good settling properties and will not be lost with the effluent. Furthermore, Al(OH)3 colloids are non-toxic, and there is no risk of secondary pollution in subsequent sludge treatment.

[0016] (3) Flocculant: It can aggregate the "micro flocs" generated by coagulation into large-volume, high-density flocs, greatly increase the settling speed, further improve the removal rate of suspended solids, COD and color, reduce the water content of sludge, and reduce the difficulty of subsequent solid-liquid separation. (4) Coagulant: It can adjust the viscosity and temperature of sewage, improve the floc formation environment, enhance floc strength, improve solid-liquid separation efficiency, and make up for the deficiencies of coagulants and flocculants.

[0017] This invention also provides a method for using equipment in paper manufacturing enterprises that can treat wastewater in stages, achieve zero discharge, and comprehensively utilize it, including the following steps: Step 1: Wastewater is injected into the sewage treatment tank through the inlet pipe. Limiting plate 1 and limiting plate 2 guide the wastewater to flow precisely to the integrated screen grid filter plate, intercepting large suspended particles (fiber fragments, mud and sand). The motor drives the rotating rod 1 to rotate, which drives the conveyor belt through the ball wheel, and transports the intercepted impurities on the filter plate to the collection box for recycling via the guide plate. Step 2: The intercepted wastewater falls into the installation frame 1. The partition plate 1 and the guide block 1 divide the wastewater into the left and right spaces. The wastewater is then filtered through the filter plate 1 (medium-sized impurities) and the filter plate 2 (fine-sized impurities) to reduce the turbidity of the wastewater. Step 3: The main gear of rotating rod one meshes with the driven gear of rotating rod two, driving the cleaning brush to rotate. At the same time, the water pump draws water and sprays it out from nozzle one through the connecting pipe, realizing simultaneous cleaning of "mechanical brushing + high-pressure rinsing". Step 4: Level 3 Deep Purification, the steps are as follows: (1). The water guiding component guides wastewater into the lower space through the connecting pipe via the second partition plate, the second material guiding block and the triangular inclined block; (2) Wastewater enters the mixing space and pH adjuster, coagulant, flocculant and coagulant aid are added in sequence through the dosing pipe. The stirring rod of the rotating rod three (tooth belt linkage drive) is fully stirred to neutralize acid and alkali, coagulate colloids to form flocs, and reduce COD and color. (3) Wastewater enters the aeration space through the inlet and is filtered by bamboo charcoal filter plate (deodorization) and activated carbon filter plate (deep adsorption); (4) Finally, the air pump enhances the degradation of organic matter by installing air pipes and nozzles for secondary aeration, so that qualified water can be discharged from the outlet pipe and returned to the papermaking section for recycling. Solid impurities in the collection box are recycled and reused, achieving zero discharge and resource recycling.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention is based on a three-stage treatment mode that can specifically remove different types of pollutants, so that the effluent indicators meet the requirements for recycling, improve the purification effect, and prevent filter media clogging through real-time cleaning, thereby reducing the frequency of downtime maintenance. This invention is based on the generation of soluble salts or settleable flocs through a chemical reaction, with no harmful byproducts, meeting environmental protection requirements, recycling fiber impurities for reuse, and closed-loop wastewater recycling, thereby reducing water resource costs. Attached Figure Description

[0019] Figure 1 This is a front view schematic diagram of the present invention; Figure 2 This is a cross-sectional view of the present invention. Figure 1 ; Figure 3 for Figure 2 Enlarged structural diagram at point A; Figure 4 This is a rear view schematic diagram of the present invention; Figure 5 for Figure 4 Enlarged structural diagram at point B; Figure 6 This is a cross-sectional view of the present invention. Figure 2 ; Figure 7 This is a cross-sectional view of the present invention. Figure 3 .

[0020] Explanation of key symbols: 1. Wastewater treatment tank; 2. Rotating rod one; 3. Ball wheel; 4. Conveyor belt; 5. Integrated screen and grating filter plate; 6. Inlet pipe; 8. Limiting plate one; 9. Limiting plate two; 10. Guide plate; 11. Collection box; 12. Mounting frame one; 13. Divider plate one; 14. Guide block one; 15. Filter plate one; 16. Filter plate two; 18. Rotating rod two; 19. Cleaning brush; 20. Connecting pipe; 21. Nozzle one; 22. Water pump; 23. Drain pipe; 24. Pumping pipe; 25. Motor; 26. Main gear; 28. 1. Gear; 29. ​​Divider plate two; 30. Guide block two; 31. Guide block three; 32. Divider plate three; 33. Connecting pipe; 34. Triangular inclined block; 35. Rotating rod three; 36. Stirring rod; 37. Mounting frame two; 38. Guide block four; 39. Bamboo charcoal filter plate; 40. Activated carbon filter plate; 41. Installing air pipe; 42. Nozzle two; 43. Rotating gear one; 44. Rotating gear two; 45. Toothed belt; 46. Water outlet pipe; 47. Air pump; 48. Exhaust pipe; 49. Controller; 50. Rotating gear three. Detailed Implementation

[0021] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0022] Please combine Figures 1 to 7 The paper mill equipment for segmented wastewater treatment with zero discharge and comprehensive utilization in this embodiment includes a wastewater treatment tank 1. The wastewater treatment tank 1 is equipped with a wastewater treatment mechanism, which includes two rotating rods 2, four ball wheels 3, two conveyor belts 4, multiple integrated screen grid filter plates 5, a water inlet pipe 6, two limiting plates 8, two limiting plates 9, and a guide plate 10. The two rotating rods 2 are symmetrically rotated and installed on the inner walls of both sides of the wastewater treatment tank 1. The four ball wheels 3 are fixedly sleeved on the two rotating rods 2 in pairs. The two conveyor belts 4 are sleeved on the corresponding two ball wheels 3 and adapted to the ball wheels 3. The multiple integrated screen grid filter plates 5 are equidistantly installed on the two conveyor belts 4. Two limiting plates 8 are symmetrically installed in the sewage treatment tank 1, one in front of the other. The two limiting plates 8 are located on one side of the two conveyor belts 4 respectively. The limiting plate 9 is installed on the two limiting plates 8. The water inlet pipe 6 is installed on the top of the sewage treatment tank 1. The bottom end of the water inlet pipe 6 extends into the sewage treatment tank 1 and is located between the two limiting plates 8. The wastewater treatment tank 1 has a discharge port on one side of its outer wall, and a guide plate 10 is installed on the discharge port. A collection box 11 is also installed on one side of the outer wall of the wastewater treatment tank 1, and the collection box 11 is adapted to the discharge port and the guide plate 10. The wastewater treatment tank 1 is equipped with a filter assembly, which includes a mounting frame 12. The mounting frame 12 is installed inside the wastewater treatment tank 1. A partition plate 13 is installed on the bottom inner wall of the mounting frame 12. A guide block 14 is installed on the top of the partition plate 13. The space inside the mounting frame 12 is divided into a left space and a right space by the partition plate 13. The left space and the right space are both located below the integrated screen grid filter plate 5. Filter plate 15 and filter plate 16 are installed in the left space and the right space, respectively.

[0023] The wastewater treatment tank 1 is equipped with a cleaning component, which includes a rotating rod 18. The rotating rod 18 is installed inside the wastewater treatment tank 1 and is located between two adjacent integrated screen grid filter plates 5. A cleaning brush 19 is fixedly sleeved on the rotating rod 18 and is in contact with the integrated screen grid filter plate 5. A connecting pipe 20 is installed inside the wastewater treatment tank 1. Multiple nozzles 21 are connected to the outer wall of the connecting pipe 20 and are located between the rotating rods 18.

[0024] The wastewater treatment tank 1 is equipped with a drive assembly, which includes a water pump 22. The water pump 22 is installed on one side of the outer wall of the wastewater treatment tank 1. A water pump pipe 24 is installed at the water inlet of the water pump 22, and a water drain pipe 23 is installed at the water outlet of the water pump 22. One end of the water drain pipe 23 extends into the wastewater treatment tank 1 and is connected to a connecting pipe 20. A motor 25 is installed on one side of the outer wall of the wastewater treatment tank 1. One end of a rotating rod 18 extends to the outside of the wastewater treatment tank 1 and is fixedly connected to the output shaft of the motor 25. A main gear 26 is fixedly sleeved on the rotating rod 18. One end of a rotating rod 28 extends to the outside of the wastewater treatment tank 1 and is fixedly sleeved with a driven gear 28. The driven gear 28 meshes with the main gear 26.

[0025] The wastewater treatment tank 1 is equipped with a connecting water guiding assembly, which includes a second partition plate 29. The second partition plate 29 is installed inside the wastewater treatment tank 1, dividing the space inside the wastewater treatment tank 1 into an upper space and a lower space. The second partition plate 29 is located below the bottom of the mounting frame 12. The second material guiding block 30 is installed on top of the second partition plate 29. The wastewater treatment tank 1 is equipped with the same third material guiding block 31 as the second material guiding block 30. A connecting pipe 33 is installed on one outer wall of the wastewater treatment tank 1. The two ends of the connecting pipe 33 extend into the upper space and the lower space, respectively. Two triangular inclined blocks 34 are symmetrically installed on the second material guiding block 30. The end of the connecting pipe 33 extending into the upper space is located between the two triangular inclined blocks 34.

[0026] A partition plate 32 is installed in the lower space, dividing the lower space into a stirring space and an aeration space. A stirring assembly is provided in the stirring space. The stirring assembly includes two rotating rods 35, which are symmetrically installed in the stirring space. Multiple stirring rods 36 are fixedly installed on each of the two rotating rods 35. One end of each of the two rotating rods 35 extends to one side of the sewage treatment tank 1 and is fixedly fitted with a rotating gear 30. A rotating gear 43 is fixedly installed on one end of the rotating rod 35, and a rotating gear 44 is fixedly installed on one end of the rotating rod 18. The rotating gear 43 and the rotating gear 44 are fitted with the same toothed belt 45.

[0027] The partition plate 32 has an opening, and the aeration space is equipped with an aeration assembly. The aeration assembly includes an air pipe 41, which is installed in the aeration space. Multiple nozzles 42 are connected to the outer wall of the air pipe 41. An air pump 47 is installed on one side of the outer wall of the sewage treatment tank 1. An exhaust pipe 48 is connected to the exhaust port of the air pump 47. A one-way valve is provided on the exhaust pipe 48. One end of the exhaust pipe 48 extends into the sewage treatment tank 1 and is connected to the air pipe 41.

[0028] An installation frame 37 is installed inside the aeration space. A guide block 38 is installed on the top of the installation frame 37. The outer wall of the guide block 38 is in contact with the inner wall of the aeration space. A bamboo charcoal filter plate 39 and an activated carbon filter plate 40 are installed inside the installation frame 37. A water outlet pipe 46 is installed on one side of the outer wall of the sewage treatment tank 1. One end of the water outlet pipe 46 extends into the aeration space. A controller 49 is installed on one side of the outer wall of the sewage treatment tank 1.

[0029] A dosing pipe is installed on one outer wall of the wastewater treatment tank 1. One end of the dosing pipe extends into the stirring space. pH adjuster, coagulant, flocculant, and coagulant aid are added to the stirring space through the dosing pipe. The effects of adding these reagents in sequence are as follows: (1) pH adjuster: Adjusts the pH value of the wastewater to the optimal reaction range for subsequent coagulation and flocculation, neutralizes excess acid and alkali in the wastewater, reduces the damage of acid and alkali to subsequent agents, promotes the dissolution or precipitation of some acidic and alkaline pollutants, and assists in subsequent removal. The reaction formula is as follows: H2SO4 + 2NaOH → Na2SO4 + 2H2O, producing soluble salts without secondary pollution; Ca (OH)2 + H2SO4 → CaSO4↓ + 2H2O, producing slightly soluble calcium sulfate, which can settle with the flocs and help remove suspended solids; H2SO4 ionization produces H + Preferred to be OH - reaction (H)+ +OH - →H2O), consumes excess OH in wastewater - This shifts the Ca(OH)2 dissolution equilibrium to the right, resulting in the continuous release of Ca. 2+ ; When Ca 2+ Concentration and SO 2- The product of concentrations ≥ the solubility product of CaSO4 (Ksp = 9.1 × 10⁻⁶). -6 At 25℃, crystallization and precipitation occur: Ca 2 + SO4 2- →CaSO4(s); The initially generated CaSO4 consists of fine crystal nuclei (particle size <1μm). By controlling the stirring intensity (80 r / min) and residence time (20~25 min), the crystal nuclei gradually grow into needle-like or plate-like crystals (particle size 5~10μm), forming "floc nuclei". Ca(OH)2(s, lime milk) + H2SO4(aq) → CaSO4(s, crystal form II) + 2H2O(I) (Crystal form II is stable calcium sulfate dihydrate, with the best sedimentation performance).

[0030] (2) Coagulant: Removes fine suspended solids and colloidal particles from wastewater, such as fiber fragments, filler CaCO3, and lignin colloids, reduces turbidity, adsorbs some dissolved organic matter, such as color substances and small molecule COD, reduces COD and color, provides "micro floc nuclei" for subsequent flocculation, and enhances floc growth. The reaction formula is as follows: Colloid) + 3H2SO4 (Al(OH)3; Aluminum sulfate completely ionizes in aqueous solution to form Al. 3+ and SO4 2- ; Al2(SO4)3(aq)→2Al 3+ (aq) + 3SO4 2- (aq), SO4 2- As inert ions, they do not participate in subsequent reactions, but only provide an electrolyte environment and compress the colloidal double layer in wastewater (assisting in destabilization). The core reaction is carried out by Al. 3+ leading; Al 3+ The hydrolysis is a stepwise reversible reaction, controlled by pH and temperature, ultimately producing Al(OH)3 colloid. The steps of the reaction are as follows: Step 1 (Primary Hydrolysis): Al 3+ + H2 2+ (aq) + H +(Equilibrium constant K1 = 1.4 × 10 at 25℃) -5 ), forming a positively charged mononuclear hydroxyl complex; Step 2 (Intermediate Hydrolysis): [Al(OH)] 2+ + H2 2] + (aq) + H + (K2=1.0×10) -6 Further hydroxylation weakens the positive charge; Step 3 (Advanced Hydrolysis): [Al(OH)2] + + H2 3(colloid) + H + (K3=8.0×10) -8 This generates amorphous Al(OH)3 colloids with a weak positive charge on the surface. Synergistic polymerization: Some mononuclear hydroxyl complexes form polynuclear complexes (such as [Al2(OH)2)) through "hydroxyl-bridged polymerization". 4+ [Al3(OH)6] 3+ These polynuclear complexes are the core precursors for the formation of "micro-flocs"; Excessive HCO3 in wastewater 3- It will consume the H generated by hydrolysis + (HCO3) - + H + →CO2↑+ H2O), which pushes the hydrolysis equilibrium to the right and promotes the formation of a large amount of Al(OH)3 colloid; Al(OH)3 colloids have a positively charged surface. They are electrostatically attracted to negatively charged pollutants in papermaking wastewater, neutralizing the surface charge and causing the colloids to lose their stability. The amorphous structure of Al(OH)3 colloid has a large specific surface area, and the surface hydroxyl groups (-OH) can adsorb soluble color substances and small molecule COD in wastewater through hydrogen bonds and van der Waals forces. The adsorbed pollutant particles combine with Al(OH)3 colloids to form "micro flocs" with a diameter of 1~5μm, providing attachment points for the subsequent bridging effect of flocculant (PAM) and ensuring the rapid generation of large-volume flocs; Al(OH)3 colloid is stable at pH 6.5–7.5 and will not undergo further hydrolysis to form AlO2. - (When pH>8) or redissolve (when pH<5); The generated flocs have good settling properties and will not be lost with the effluent. Furthermore, Al(OH)3 colloids are non-toxic, and there is no risk of secondary pollution in subsequent sludge treatment.

[0031] (3) Flocculant: It can aggregate the "micro flocs" generated by coagulation into large-volume, high-density flocs, greatly increase the settling speed, further improve the removal rate of suspended solids, COD and color, reduce the water content of sludge, and reduce the difficulty of subsequent solid-liquid separation. (4) Coagulant: It can adjust the viscosity and temperature of sewage, improve the floc formation environment, enhance floc strength, improve solid-liquid separation efficiency, and make up for the deficiencies of coagulants and flocculants.

[0032] This invention also provides a method for using equipment in paper manufacturing enterprises that can treat wastewater in stages, achieve zero discharge, and comprehensively utilize it, including the following steps: Step 1: Wastewater is injected into the sewage treatment tank 1 through the inlet pipe 6. Limiting plate 1 8 and limiting plate 2 9 guide the wastewater to flow precisely to the integrated screen grid filter plate 5, intercepting large suspended particles (fiber fragments, mud and sand). Motor 25 drives the rotating rod 1 2 to rotate, which drives the conveyor belt 4 through the ball wheel 3, and transports the intercepted impurities on the filter plate to the collection box 11 for recycling via the guide plate 10. Step 2: The intercepted wastewater falls into the installation frame 12. The partition plate 13 and the guide block 14 divert the wastewater to the left and right spaces. It is then filtered through the filter plate 15 (medium-sized impurities) and the filter plate 26 (fine-sized impurities) to reduce the turbidity of the wastewater. Step 3: The main gear 26 of the rotating rod 12 meshes with the driven gear 28 of the rotating rod 28, driving the cleaning brush 19 to rotate. At the same time, the water pump 22 draws water and sprays it out from the nozzle 21 through the connecting pipe 20, realizing simultaneous cleaning of "mechanical brushing + high pressure rinsing". Step 4: Level 3 Deep Purification, the steps are as follows: (1). The water guiding component guides wastewater into the lower space through the connecting pipe 33 via the partition plate 29, the material guiding block 30 and the triangular inclined block 34; (2) Wastewater enters the mixing space and pH adjuster, coagulant, flocculant and coagulant aid are added in sequence through the dosing pipe. The stirring rod 36 of the rotating rod 35 (driven by the toothed belt 45) is fully stirred to neutralize acid and alkali, coagulate colloids to form flocs, and reduce COD and color. (3) Wastewater enters the aeration space through the inlet and is filtered by bamboo charcoal filter plate 39 (odor removal) and activated carbon filter plate 40 (deep adsorption); (4). Finally, the air pump 47 aerates the water by installing the air pipe 41 and the nozzle 2 42, which enhances the degradation of organic matter and allows qualified water to be discharged from the outlet pipe 26. It can be returned to the papermaking section for recycling. The solid impurities in the collection box 11 are recycled and reused, achieving zero discharge and resource recycling.

[0033] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A device for paper manufacturing enterprises that can treat wastewater in stages for zero discharge and comprehensive utilization, characterized in that, include: The wastewater treatment tank is equipped with a wastewater treatment mechanism, which includes two rotating rods, four ball wheels, two conveyor belts, multiple integrated screen grid filter plates, an inlet pipe, two limiting plates, two limiting plates, and a guide plate. The two rotating rods are symmetrically rotated and installed on the inner walls of both sides of the wastewater treatment tank. The four ball wheels are fixedly fitted on the two rotating rods in pairs. The two conveyor belts are fitted on the corresponding two ball wheels and adapted to the ball wheels. The multiple integrated screen grid filter plates are equidistantly installed on the two conveyor belts. Two limiting plates are symmetrically installed in the sewage treatment tank, one in front of the other. The two limiting plates are located on one side of the two conveyor belts respectively. The second limiting plate is installed on the two limiting plates. The water inlet pipe is installed on the top of the sewage treatment tank. The bottom end of the water inlet pipe extends into the sewage treatment tank and is located between the two limiting plates. The wastewater treatment tank has a discharge port on one side of its outer wall, and a guide plate is installed on the discharge port. A collection box is installed on one side of the wastewater treatment tank, and the collection box is compatible with the discharge port and the guide plate.

2. The equipment for paper mills that can treat wastewater in stages for zero discharge and comprehensive utilization as described in claim 1, characterized in that, The wastewater treatment tank is equipped with a filter assembly, which includes a mounting frame 1 installed inside the wastewater treatment tank. A partition plate 1 is installed on the bottom inner wall of the mounting frame 1, and a guide block 1 is installed on the top of the partition plate 1. The space inside the mounting frame 1 is divided into a left space and a right space by the partition plate 1. Both the left space and the right space are located below the integrated screen grid filter plate. Filter plate 1 and filter plate 2 are installed in the left space and the right space, respectively.

3. The equipment for paper mills that can treat wastewater in stages, achieve zero discharge, and comprehensively utilize it, as described in claim 1, is characterized in that... The wastewater treatment tank is equipped with a cleaning component, which includes a rotating rod 2. The rotating rod 2 is installed inside the wastewater treatment tank and is located between two adjacent integrated screen grid filter plates. The cleaning brush is fixedly sleeved on the rotating rod 2 and is in contact with the integrated screen grid filter plate. A connecting pipe is installed inside the wastewater treatment tank, and multiple nozzles 1 are connected to the outer wall of the connecting pipe. The connecting pipe is located between the rotating rod 2.

4. The equipment for paper mills that can treat wastewater in stages, achieve zero discharge, and comprehensively utilize it, as described in claim 3, is characterized in that... The wastewater treatment tank is equipped with a drive assembly, which includes a water pump. The water pump is installed on one outer wall of the wastewater treatment tank. A water pump inlet is equipped with a water pump pipe, and a water pump outlet is equipped with a water pump outlet. One end of the water pump outlet extends into the wastewater treatment tank and is connected to a connecting pipe. A motor is installed on one outer wall of the wastewater treatment tank. One end of a rotating rod extends to the outside of the wastewater treatment tank and is fixedly connected to the output shaft of the motor. A main gear is fixedly mounted on the rotating rod. One end of the rotating rod extends to the outside of the wastewater treatment tank and is fixedly mounted with a driven gear. The driven gear meshes with the main gear.

5. The equipment for paper mills that can treat wastewater in stages for zero discharge and comprehensive utilization as described in claim 2, characterized in that, The wastewater treatment tank is equipped with a connecting water guiding assembly, which includes a second partition plate. The second partition plate is installed inside the wastewater treatment tank, dividing the space inside the wastewater treatment tank into an upper space and a lower space. The second partition plate is located below the bottom of the first mounting frame. The second material guiding block is installed on top of the second partition plate. The wastewater treatment tank and the second material guiding block share the same third material guiding block. A connecting pipe is installed on one outer wall of the wastewater treatment tank, with both ends of the connecting pipe extending into the upper space and the lower space, respectively. Two triangular inclined blocks are symmetrically installed on the second material guiding block, and the end of the connecting pipe extending into the upper space is located between the two triangular inclined blocks.

6. The equipment for paper mills that can treat wastewater in stages, achieve zero discharge, and comprehensively utilize it, as described in claim 3, is characterized in that... A partition plate three is installed in the lower space, dividing the lower space into a stirring space and an aeration space. A stirring assembly is provided in the stirring space, and the stirring assembly includes two rotating rods three. The two rotating rods three are symmetrically installed in the stirring space. Multiple stirring rods are fixedly installed on each of the two rotating rods three. One end of each of the two rotating rods three extends to one side of the sewage treatment tank and is fixedly fitted with a rotating gear three. A rotating gear one is fixedly installed on one end of the rotating rod three, and a rotating gear two is fixedly installed on one end of the rotating rod two. The rotating gear one and the rotating gear two are fitted with the same toothed belt.

7. The equipment for segmented wastewater treatment and comprehensive utilization in paper mills as described in claim 6, characterized in that, The partition plate 3 has an opening, and the aeration space is equipped with an aeration assembly. The aeration assembly includes an air pipe, which is installed in the aeration space. Multiple nozzles 2 are connected to the outer wall of the air pipe. An air pump is installed on one side of the outer wall of the sewage treatment tank. The exhaust port of the air pump is connected to an exhaust pipe, which is equipped with a one-way valve. One end of the exhaust pipe extends into the sewage treatment tank and is connected to the air pipe.

8. The equipment for paper mills that can treat wastewater in stages for zero discharge and comprehensive utilization as described in claim 7, characterized in that, An installation frame two is installed inside the aeration space. A guide block four is installed on the top of the installation frame two. The outer wall of the guide block four is in contact with the inner wall of the aeration space. A bamboo charcoal filter plate and an activated carbon filter plate are installed inside the installation frame two. A water outlet pipe is installed on one side of the outer wall of the sewage treatment tank. One end of the water outlet pipe extends into the aeration space. A controller is installed on one side of the outer wall of the sewage treatment tank.

9. The equipment for segmented wastewater treatment and comprehensive utilization in paper mills as described in claim 6, characterized in that, A dosing pipe is installed on one outer wall of the wastewater treatment tank. One end of the dosing pipe extends into the stirring space. pH adjuster, coagulant, flocculant, and coagulant aid are added to the stirring space through the dosing pipe. The effects of adding these reagents in sequence are as follows: (1) pH adjuster: Adjusts the pH value of the wastewater to the optimal reaction range for subsequent coagulation and flocculation, neutralizes excess acid and alkali in the wastewater, reduces the damage of acid and alkali to subsequent agents, promotes the dissolution or precipitation of some acidic and alkaline pollutants, and assists in subsequent removal. The reaction formula is as follows: H2SO4 + 2NaOH → Na2SO4 + 2H2O, producing soluble salts without secondary pollution; Ca (OH)2 + H2SO4 → CaSO4↓ + 2H2O, producing slightly soluble calcium sulfate, which can settle with the flocs and help remove suspended solids; H2SO4 ionization produces H + Preferred to be OH - reaction (H) + +OH - →H2O), consumes excess OH in wastewater - This shifts the Ca(OH)2 dissolution equilibrium to the right, resulting in the continuous release of Ca. 2+ ; When Ca 2+ Concentration and SO 2- The product of concentrations ≥ the solubility product of CaSO4 (Ksp = 9.1 × 10⁻⁶). -6 At 25℃, crystallization and precipitation occur: Ca 2 + SO4 2- →CaSO4(s); The initially generated CaSO4 consists of fine crystal nuclei (particle size <1μm). By controlling the stirring intensity (80 r / min) and residence time (20~25 min), the crystal nuclei gradually grow into needle-like or plate-like crystals (particle size 5~10μm), forming "floc nuclei". Ca(OH)2(s, lime milk) + H2SO4(aq) → CaSO4(s, crystal form II) + 2H2O(I) (Crystal form II is stable calcium sulfate dihydrate, with the best sedimentation performance). (2) Coagulant: Removes fine suspended solids and colloidal particles from wastewater, such as fiber fragments, filler CaCO3, and lignin colloids, reduces turbidity, adsorbs some dissolved organic matter, such as color substances and small molecule COD, reduces COD and color, provides "micro floc nuclei" for subsequent flocculation, and enhances floc growth. The reaction formula is as follows: Colloid) + 3H2SO4 (Al(OH)3; Aluminum sulfate completely ionizes in aqueous solution to form Al. 3+ and SO4 2- ; Al2(SO4)3(aq)→2Al 3+ (aq) + 3SO4 2- (aq), SO4 2- As inert ions, they do not participate in subsequent reactions, but only provide an electrolyte environment and compress the colloidal double layer in wastewater (assisting in destabilization). The core reaction is carried out by Al. 3+ leading; Al 3+ The hydrolysis is a stepwise reversible reaction, controlled by pH and temperature, ultimately producing Al(OH)3 colloid. The steps of the reaction are as follows: Step 1 (Primary Hydrolysis): Al 3+ + H2 2+ (aq) + H + (Equilibrium constant K1 = 1.4 × 10 at 25℃) -5 ), forming a positively charged mononuclear hydroxyl complex; Step 2 (Intermediate Hydrolysis): [Al(OH)] 2+ + H2 2] + (aq) + H + (K2=1.0×10) -6 Further hydroxylation weakens the positive charge; Step 3 (Advanced Hydrolysis): [Al(OH)2] + + H2 3(colloid) + H + (K3=8.0×10) -8 This process generates amorphous Al(OH)3 colloids with a weak positive charge on the surface. Copolymerization: Some mononuclear hydroxyl complexes form polynuclear complexes (such as [Al2(OH)2) through "hydroxyl-bridged polymerization"). 4+ [Al3(OH)6] 3+ These polynuclear complexes are the core precursors for the formation of "micro-flocs"; Excessive HCO3 in wastewater 3- It will consume the H generated by hydrolysis + (HCO3) - + H + →CO2↑+ H2O), which pushes the hydrolysis equilibrium to the right and promotes the formation of a large amount of Al(OH)3 colloid; Al(OH)3 colloids have a positively charged surface. They are electrostatically attracted to negatively charged pollutants in papermaking wastewater, neutralizing the surface charge and causing the colloids to lose their stability. The amorphous structure of Al(OH)3 colloid has a large specific surface area, and the surface hydroxyl groups (-OH) can adsorb soluble color substances and small molecule COD in wastewater through hydrogen bonds and van der Waals forces. The adsorbed pollutant particles combine with Al(OH)3 colloids to form "micro flocs" with a diameter of 1~5μm, providing attachment points for the subsequent bridging effect of flocculant (PAM) and ensuring the rapid generation of large-volume flocs; Al(OH)3 colloid is stable at pH 6.5–7.5 and will not undergo further hydrolysis to form AlO2. - (When pH>8) or redissolve (when pH<5); The generated flocs have good settling properties and will not be lost with the effluent. Furthermore, Al(OH)3 colloids are non-toxic, and there is no risk of secondary pollution in the subsequent treatment of sludge. (3) Flocculant: It can aggregate the "micro flocs" generated by coagulation into large-volume, high-density flocs, greatly increase the settling speed, further improve the removal rate of suspended solids, COD and color, reduce the water content of sludge, and reduce the difficulty of subsequent solid-liquid separation. (4) Coagulant: It can adjust the viscosity and temperature of sewage, improve the floc formation environment, enhance floc strength, improve solid-liquid separation efficiency, and make up for the deficiencies of coagulants and flocculants.

10. A method for using equipment in a paper mill that can treat wastewater in stages for zero discharge and comprehensive utilization, characterized in that, Includes the equipment for segmented wastewater treatment and zero discharge and comprehensive utilization in paper mills as described in claim 1, and the following steps: Step 1: Wastewater is injected into the sewage treatment tank through the inlet pipe. Limiting plate 1 and limiting plate 2 guide the wastewater to flow precisely to the integrated screen grid filter plate, intercepting large suspended particles (fiber fragments, mud and sand). The motor drives the rotating rod 1 to rotate, which drives the conveyor belt through the ball wheel, and transports the intercepted impurities on the filter plate to the collection box for recycling via the guide plate. Step 2: The intercepted wastewater falls into the installation frame 1. The partition plate 1 and the guide block 1 divide the wastewater into the left and right spaces. The wastewater is then filtered through the filter plate 1 (medium-sized impurities) and the filter plate 2 (fine-sized impurities) to reduce the turbidity of the wastewater. Step 3: The main gear of rotating rod one meshes with the driven gear of rotating rod two, driving the cleaning brush to rotate. At the same time, the water pump draws water and sprays it out from nozzle one through the connecting pipe, realizing simultaneous cleaning of "mechanical brushing + high-pressure rinsing". Step 4: Level 3 Deep Purification, the steps are as follows: (1). The water guiding component guides wastewater into the lower space through the connecting pipe via the second partition plate, the second material guiding block and the triangular inclined block; (2) Wastewater enters the mixing space and pH adjuster, coagulant, flocculant and coagulant aid are added in sequence through the dosing pipe. The stirring rod of the rotating rod three (tooth belt linkage drive) is fully stirred to neutralize acid and alkali, coagulate colloids to form flocs, and reduce COD and color. (3) Wastewater enters the aeration space through the inlet and is filtered by bamboo charcoal filter plate (deodorization) and activated carbon filter plate (deep adsorption); (4) Finally, the air pump enhances the degradation of organic matter by installing air pipes and nozzles for secondary aeration, so that qualified water can be discharged from the outlet pipe and returned to the papermaking section for recycling. Solid impurities in the collection box are recycled and reused, achieving zero discharge and resource recycling.

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