A two-phase sulfate reduction device for preventing sludge calcification and a treatment method thereof

Abstract

The present invention discloses a two-phase sulfate reduction device and treatment method for preventing sludge calcification, belonging to the technical field of wastewater treatment in environmental engineering. This device combines a two-phase sulfate reduction anaerobic reactor with an alloy catalyst, rationally arranges a two-phase alloy catalyst connection unit within the device body, and utilizes the unique ability of porous alloy catalyst materials to release free electrons into the water and polarize the water, thereby changing the electrostatic potential of the water, preventing sludge calcification during the wastewater treatment process, and ensuring wastewater treatment efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment in environmental engineering, and more particularly relates to a two-phase sulfate reduction device for preventing sludge calcification and a treatment method thereof. Background Art

[0002] The papermaking industry uses large amounts of sulfuric acid or sulfates in processes such as papermaking, pulp bleaching, and pulping, resulting in high concentrations of sulfates in the discharged wastewater. Anaerobic biological treatment technology is widely used to treat high-concentration organic wastewater due to its high energy recovery efficiency and high load rate. However, calcium carbonate is required as a filler and coating in the papermaking industry's production processes, resulting in a large amount of calcium ions in the discharged wastewater. During the anaerobic biological treatment process, calcium ions easily combine with carbonate or bicarbonate ions to form precipitates, which are adsorbed and filled in the pores of the sludge, deposited within the sludge, or coated on the surface of the sludge, causing calcification of the granular sludge and reducing its activity and settling performance. In addition, sludge calcification can also affect the circulation system of the anaerobic reactor, causing scaling and clogging of the reactor, ultimately reducing the treatment efficiency of the anaerobic system.

[0003] At present, the main methods for controlling sludge calcification in the anaerobic process of papermaking wastewater are chemical precipitation, controlling the calcium deposition process and replacing calcified sludge. ① Chemical precipitation refers to adding alkaline reagents such as soda ash or sodium hydroxide before the wastewater enters the anaerobic system to react with Ca 2+ Formation of precipitate, Ca 2+ Removed in the form of insoluble salts, thereby reducing the Ca entering the anaerobic system 2+ concentration, reducing the occurrence of sludge calcification. However, adding alkaline reagents will make the wastewater alkaline too high, affecting the anaerobic biological treatment process, and the cost of the agent speculation is very high. ② Controlling the calcium deposition process means adjusting the pH value of the anaerobic system by adding acid to prevent Ca 2+ Formation of precipitate, while reducing Ca 2+ The retention rate is high; the effluent from the secondary sedimentation tank is returned to dilute the influent of the anaerobic system and reduce the Ca 2+ According to the formation mechanism of sludge calcification and the solubility product of calcium carbonate, pH and alkalinity are the main factors affecting calcium carbonate deposition. Too high pH will accelerate the precipitation of calcium carbonate, while too low pH will lead to the accumulation of volatile fatty acids, acidification of the reactor, and reduction of the activity of methanogens. Therefore, adding acid to adjust the pH value of the anaerobic system can theoretically reduce the concentration of Ca 2+ The retention rate is high, but the operation is difficult, and if the pH is not well controlled, it will affect the treatment efficiency of the anaerobic system. 2+ concentration, reducing Ca 2+ Retention in anaerobic systems. But the total Ca 2+The concentration has not decreased, so it cannot eliminate Ca from the source. 2+ The impact of sludge calcification can only be mitigated to a certain extent. ③ Calcified sludge replacement refers to the timely removal of calcified sludge and replacement with fresh sludge to prevent sludge calcification from affecting the treatment efficiency of the anaerobic system. This method is simple to operate, but it has problems such as high cost, difficult to control sludge concentration, and long sludge incubation time.

[0004] Chemical precipitation, controlled calcium deposition, and calcified sludge replacement methods often increase the alkalinity of the anaerobic system, impacting the anaerobic biological treatment process and increasing costs. Therefore, a technology that can prevent sludge calcification during the anaerobic process without affecting the process, while being low-cost, energy-efficient, and requiring no subsequent treatment, is urgently needed. Summary of the Invention

[0005] 1. Problem to be solved

[0006] To address the problems of sludge calcification, reactor clogging, and reduced anaerobic system treatment efficiency in existing sulfate wastewater treatment technologies, the present invention provides a two-phase sulfate reduction device and treatment method that prevents sludge calcification. This invention combines a two-phase sulfate reduction anaerobic reactor with an alloy catalyst, rationally arranges a two-phase alloy catalyst connection unit within the device body, and utilizes the unique ability of porous alloy catalyst materials to release free electrons into the water and polarize the water, thereby changing the electrostatic potential of the water, preventing sludge calcification during the wastewater treatment process and ensuring the anaerobic system's treatment efficiency for sulfate organic wastewater.

[0007] 2. Technical solution

[0008] In order to solve the above problems, the technical solutions adopted by the present invention are as follows:

[0009] The present invention provides a two-phase sulfate reduction device for preventing sludge calcification, comprising a device body, an internal circulation unit, and an alloy catalyst two-phase connection unit. The device body is provided with an acid-generating zone, a methane-generating zone, and a precipitation zone from bottom to top. A three-phase separator for the acid-generating zone is provided on the top of the acid-generating zone, and a three-phase separator for the methane-generating zone is provided between the methane-generating zone and the precipitation zone.

[0010] The internal circulation unit includes a cyclone gas-liquid separator, an exhaust pipe, an acid-producing area riser pipe, a methane-producing area riser pipe, and a return pipe. The cyclone gas-liquid separator is arranged at the top of the device body, the exhaust pipe is located at the top of the cyclone gas-liquid separator, the cyclone gas-liquid separator is connected to the acid-producing area three-phase separator through the acid-producing area riser pipe, the cyclone gas-liquid separator is connected to the methane-producing area three-phase separator through the methane-producing area riser pipe, and the cyclone gas-liquid separator is connected to the methane-producing area through the return pipe;

[0011] The alloy catalyst two-phase connection unit is arranged between the acid-generating zone and the methane-generating zone, and is used to connect the acid-generating zone and the methane-generating zone. The alloy catalyst two-phase connection unit includes a first alloy catalyst zone, a second alloy catalyst zone and a U-shaped pipe. The first alloy catalyst zone is arranged in the water inlet pipe connected below the device body, and the second alloy catalyst zone is arranged in the U-shaped pipe. The U-shaped pipe is arranged on the side wall of the reactor body between the acid-generating zone and the methane-generating zone. One end opening of the U-shaped pipe is connected to the acid-generating zone, and the other end opening is connected to the methane-generating zone.

[0012] Preferably, a baffle is provided between the acid-producing zone and the methane-producing zone, and the baffle is located between the two end openings of the U-shaped pipe.

[0013] Preferably, the volume ratio between the acidogenic zone, the methanogenic zone and the precipitation zone is 2:4:1.

[0014] Preferably, a pH adjustment port is provided on the side of the U-shaped pipe.

[0015] Preferably, an overflow weir is provided in the sedimentation area, a water outlet is provided on the upper side of the sedimentation area, and the overflow weir is located below the water outlet.

[0016] The present invention provides a two-phase sulfate reduction treatment method for preventing sludge calcification, which uses the above-mentioned device for treatment. The treatment method specifically includes:

[0017] S1. Inoculating anaerobic sludge in the acid-generating zone and the methane-generating zone, and introducing sulfate organic wastewater into the acid-generating zone through the water inlet pipe to contact the sludge to degrade organic matter in the wastewater. The sulfate organic wastewater contacts the porous alloy catalyst material in the first alloy catalyst zone in the water inlet pipe. The porous alloy catalyst material releases free electrons to the sulfate organic wastewater, neutralizing calcium and magnesium ions in the water, changing the electrostatic potential of the water, and preventing calcification of the anaerobic sludge in the acid-generating zone.

[0018] S2. The wastewater treated in the acid-generating zone is separated in the three-phase separator in the acid-generating zone. The sludge is retained and returned to the acid-generating zone. The generated gas enters the cyclone gas-liquid separator through the acid-generating zone riser. The effluent enters the methane-generating zone through a U-shaped pipe. Inside the U-shaped pipe, the effluent comes into contact with the porous alloy catalyst material in the second alloy catalyst zone, further preventing the anaerobic sludge in the acid-generating zone from calcifying.

[0019] S3, the effluent after the treatment in step S2 enters the methanogenic zone to further degrade the organic matter in the wastewater, the wastewater after the treatment in the methanogenic zone is separated in the three-phase separator of the methanogenic zone, the sludge is intercepted and returned to the methanogenic zone, the generated gas enters the cyclone gas-liquid separator through the riser pipe of the methanogenic zone, and the effluent is discharged after sedimentation in the sedimentation zone;

[0020] S4. The gas generated in step S2 and step S3 carries the reaction mixture and enters the cyclone gas-liquid separator for gas-liquid separation. The gas is discharged through the exhaust pipe, and the liquid re-enters the methanogenizing zone through the reflux pipe, realizing the internal circulation of the mixed liquid in the methanogenizing zone.

[0021] Preferably, the pH value of the acid-generating zone is 4.0-4.5, and the ratio of sodium bicarbonate / COD in the influent is controlled at 1 / 10-1 / 50.

[0022] Preferably, the first alloy catalyst zone or the second alloy catalyst zone is filled with a porous alloy catalyst material of 1 / 200 of the effective volume of the device body, and the water body is controlled to contact the porous alloy catalyst material at a flow rate of 1-5 m / s.

[0023] Preferably, the effluent discharged from step S3 is pH-adjusted and then mixed with the wastewater treated in the acid-producing area and fed into the methanogenic area to maintain the pH value of the methanogenic area at 6.8-8.5.

[0024] Preferably, the porous alloy catalyst material is a columnar crystal structure material, and is made of 30%-50% Zn, 15-35% Cu, 10%-30% Co, 5%-20% Ni, 0.5%-10% Fe and 0.1%-5% Sn by mass.

[0025] 3. Beneficial effects

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) A two-phase sulfate reduction device for preventing sludge calcification of the present invention combines an alloy catalyst with a two-phase sulfate reduction anaerobic reactor. A porous alloy catalyst is provided at the water inlet pipe of the device body and the connection between the two phases. The water flows at a flow rate of 1-5 m / s and contacts the alloy catalyst. The alloy catalyst releases free electrons into the water body, neutralizes cations such as calcium and magnesium in the water body, changes the electrostatic potential of the water body, and prevents sludge calcification in the two-phase sulfate reduction device.

[0028] (2) In a two-phase sulfate reduction device for preventing sludge calcification, the acid-producing zone and the methane-producing zone are completely separated by a baffle. After the effluent from the acid-producing zone is separated by a three-phase separator in the acid-producing zone, it enters the methane-producing zone from a U-shaped pipe on the side wall under the action of an upward flow rate. The volume ratio of the methane-producing zone to the acid-producing zone is 2:1, which not only increases the hydraulic retention time of the methane-producing zone and reduces the hydraulic retention time of the acid-producing zone, but also facilitates the acclimation of different microorganisms in different zones.

[0029] (3) The present invention provides a two-phase sulfate reduction treatment method for preventing sludge calcification. By controlling the ratio of sodium bicarbonate to COD in the influent to 1 / 10-1 / 50 and maintaining the pH value of the acid-producing zone between 4.0 and 4.5, the acid-producing zone undergoes ethanol fermentation, providing ethanol for the methane-producing zone. The methane-producing zone then utilizes ethanol as a substrate to construct an in situ direct interspecies electron transfer system, thereby promoting the methane production process and the degradation of organic pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic structural diagram of a two-phase sulfate reduction device for preventing sludge calcification according to the present invention;

[0031] In the picture:

[0032] 100. Device body; 101. Water inlet pipe; 110. Acid generating area; 111. Three-phase separator in the acid generating area;

[0033] 120, methanogenic zone; 121, three-phase separator in methanogenic zone; 130, sedimentation zone; 131, overflow weir;

[0034] 132, water outlet; 200, internal circulation unit; 210, cyclone gas-liquid separator; 220, exhaust pipe;

[0035] 230, riser pipe in acid-producing area; 240, riser pipe in methane-producing area; 250, return pipe;

[0036] 300, alloy catalyst two-phase connection unit; 310, first alloy catalyst zone;

[0037] 320, second alloy catalyst zone; 330, U-shaped pipe;

[0038] 340, pH adjustment port; 400, baffle. DETAILED DESCRIPTION

[0039] The present invention will be further described below with reference to specific embodiments.

[0040] The present invention provides a two-phase sulfate reduction device for preventing sludge calcification, which combines an alloy catalyst with a two-phase sulfate reduction anaerobic reactor. The alloy catalyst material has a special columnar crystal structure made of metals such as iron (Fe), cobalt (Co), nickel (Ni), and zinc (Zn). The alloy catalyst can release free electrons into the water body, neutralize positive charges such as calcium and magnesium ions in the water body, change the electrostatic potential of the water body, and significantly reduce the sludge calcification rate, thereby achieving a scale inhibition effect.

[0041] Example 1

[0042] The target water treated in this example was wastewater from a Jiangsu chemical company with a daily treatment capacity of 1000 t / d. The influent contained approximately 1714 mg / L of calcium ions. Pipeline scaling and sludge calcification were severe, requiring pipe and granular sludge replacement every six months, severely impacting the company's normal production. The company's influent water quality is shown in Table 1. Water quality was regularly tested during treatment, and the average concentration was ultimately used.

[0043] Table 1 Water quality before and after wastewater treatment of Example 1

[0044]

[0045] like Figure 1 As shown, a two-phase sulfate reduction device for preventing sludge calcification used in this embodiment includes a device body 100, an internal circulation unit 200 and an alloy catalyst two-phase connection unit 300. The device body 100 is provided with an acid-generating zone 110, a methane-generating zone 120 and a precipitation zone 130 with a volume ratio of 2:4:1 from bottom to top. A three-phase separator 111 for the acid-generating zone is provided on the top of the acid-generating zone 110, and a three-phase separator 121 for the methane-generating zone is provided between the methane-generating zone 120 and the precipitation zone 130; the internal circulation unit 200 includes a cyclone gas-liquid separator 210, an exhaust pipe 220, an acid-generating zone riser 230, a methane-generating zone riser 240 and a reflux pipe 250. The cyclone gas-liquid separator 210 is provided on the top of the device body 100, and the exhaust pipe 220 is located at the top of the cyclone gas-liquid separator 210, the cyclone gas-liquid separator 210 is connected to the acid-producing area three-phase separator 111 through the acid-producing area riser 230, the cyclone gas-liquid separator 210 is connected to the methane-producing area three-phase separator 121 through the methane-producing area riser 240, and the cyclone gas-liquid separator 210 is connected to the methane-producing area 120 through the reflux pipe 250; the alloy catalyst two-phase connection unit 300 is arranged between the acid-producing area 110 and the methane-producing area 120, for connecting the acid-producing area 110 and the methane-producing area 120, a baffle 400 is arranged between the acid-producing area 110 and the methane-producing area 120, and the baffle 400 is located between the two end openings of the U-shaped pipe 330, and a pH adjustment port 340 is arranged on the side of the U-shaped pipe 330. The alloy catalyst two-phase connection unit 300 includes a first alloy catalyst zone 310, a second alloy catalyst zone 320 and a U-shaped pipe 330. The first alloy catalyst zone 310 is arranged in the water inlet pipe 101 connected below the device body 100, and the second alloy catalyst zone 320 is arranged in the U-shaped pipe 330. The U-shaped pipe 330 is arranged on the side wall of the reactor body between the acid-producing zone 110 and the methane-producing zone 120. One end opening of the U-shaped pipe 330 is connected to the acid-producing zone 110, and the other end opening is connected to the methane-producing zone 120. In addition, the device body 100 is provided with an insulation layer, and the internal temperature of the device is maintained at 35±1°C through water bath circulation.

[0046] The device startup and phase separation process of this embodiment is as follows: a method combining pH regulation and kinetic control is adopted, wherein the pH regulation is to control the pH of the acid-producing zone 110 between 4.0-6.5. Taking into account the need to carry out ethanol-type fermentation, the pH of the acid-producing phase needs to be controlled between 4.0-4.5, while the methane phase only needs to be maintained at a neutral to alkaline pH. The principle of kinetic control is to be achieved based on the difference in growth rates between acid-producing bacteria and MPA. The growth rate of acid-producing bacteria is fast and the generation time is short, generally 10-30 minutes; while the growth rate of MPA is slow and the generation time is long, generally 4-6 days. Therefore, the growth of bacteria in the reactor is optimized by controlling the HRT to achieve phase separation.

[0047] First, the sludge was acclimated at HRT = 36 hours. After the device achieved stable COD removal and sulfate reduction effects, the influent OLR was improved by gradually shortening the HRT, and the HRT was shortened to 24 hours, 16 hours, 12 hours, 8 hours and 6 hours in sequence. During the experiment, the pH of the acid-producing zone 110 of the device was continuously monitored. When the pH dropped to between 4.0-4.5, it was ensured that the pH remained in this range to achieve ethanol-type fermentation. If the pH is lower than 4.0, the concentration of sodium bicarbonate in the influent will be increased to buffer the excess acidity of the acid-producing phase. At the same time, 20 g / L of sodium bicarbonate solution was introduced into the methane-producing zone 120 through the pH regulating port 340 to maintain the pH value of the methane-producing zone 120 at 7.5-8.5, completing the two-phase separation of the acid-producing zone 110 and the methane-producing zone 120.

[0048] The first alloy catalyst zone 310 and the second alloy catalyst zone 320 are equipped with a porous alloy catalyst composed of 37.25% Zn, 31.44% Cu, 18.44% Co, 5.22% Ni, 5.72% Fe, and 1.93% Sn. The porous alloy catalyst is cylindrical, 8 cm in diameter and 20 cm long. Multiple channels are arranged along the axis of the alloy catalyst cylinder to increase the contact area between the catalyst and the water flow. This alloy catalyst material has the unique ability to release free electrons into the fluid medium and polarize the fluid medium. When wastewater flows through the alloy catalyst material at a certain flow rate, it releases free electrons, polarizing the fluid. This neutralizes calcium and magnesium ions in the water, changes the electrostatic potential of the water, and prevents calcification of anaerobic sludge in the acid-generating zone 110 and the methane-generating zone 120. During the operation of the device, an external circulation is added to the methane production zone 120 of the device to maintain an upward flow rate of about 1 m / h, so that the granular sludge in the reactor is in a fluidized state and calcification of the granular sludge is not likely to occur.

[0049] After one year of stable operation, the granular sludge from the device was analyzed and tested alongside granular sludge from the company's IC reactor treating the same wastewater for one year. The results included mixed liquor suspended solids (MLSS) and mixed liquid volatile suspended solids (MLVSS) to characterize the organic content of the sludge, a particle size analyzer to characterize the particle size distribution, and an energy dispersive spectrometer (EDS) to characterize the calcium content. The results are shown in Table 2.

[0050] Table 2 Physicochemical properties and element contents of granular sludge from the device of Example 1

[0051]

[0052] In this example, the organic component (MLVSS / MLSS) content of the granular sludge after one year of operation using the conventional IC reactor was only 66%, while that of the granular sludge using a two-phase sulfate reduction device that prevents sludge calcification reached 82%. This is because the CO2 produced by the oxidation of organic components in the conventional IC reactor is partially converted into carbonates, which then react with the Ca in the system. 2+ A white CaCO3 precipitate is formed and attached to the surface of the granular sludge, which reduces the organic components in the sludge and increases the corresponding ash content, resulting in sludge calcification. The alloy catalyst material can release free electrons into the water body when water flows through, causing the fluid to polarize, neutralizing calcium and magnesium ions, changing the electrostatic potential of the water body, and thus preventing the occurrence of sludge calcification. The test results of the sludge particle size show that the particle size of the calcified granular sludge is significantly increased. The particle size of the granular sludge in the device of this embodiment is 1020um, while the average sludge particle size of the granular sludge in the traditional IC reactor reaches 1640um. In addition, the EDS test results show that the calcium content in the granular sludge of the traditional IC reactor after one year of operation reached 9.54%, and obvious calcification occurred. However, the calcium ion concentration in the device of this embodiment is only 0.15%, and no calcification occurs.

[0053] The chemical wastewater was treated using the device of this embodiment. The system COD removal rate and sulfate reduction rate were both above 80%, and sludge calcification did not occur. Currently, the system has been in operation for one year without the need to replace the pipes and granular sludge.

[0054] Example 2

[0055] The basic structure of the apparatus of this embodiment is the same as that of Example 1, except that: in the treatment method of this embodiment, due to the higher COD, sulfate, and calcium ion concentrations in the influent, the amount of alloy catalyst needs to be increased. In addition, the HRT of the acid-producing phase should not be too low during phase separation, otherwise a large amount of sodium bicarbonate reagent will be consumed to neutralize the excess acidity, increasing operating costs. Sodium bicarbonate and sodium hydroxide can be used to jointly adjust the pH values ​​of the acid-producing zone 110 and the methane-producing zone 120. Due to the high sulfate concentration in the influent, the pH of the methane-producing phase needs to be controlled in the higher range of pH 7.5-8.5 to reduce the toxic inhibitory effect of hydrogen sulfide, a sulfate reduction product.

[0056] The target water treated in this example was wastewater from a Henan food company, with a daily treatment capacity of 1,150 tons. COD, sulfate, and calcium ion concentrations were 12,455 mg / L, 3,847 mg / L, and 3,345 mg / L, respectively. Previously, the wastewater treatment process had been plagued by severe sludge calcification, requiring the company to replace a batch of sludge every three months to mitigate the problem.

[0057] The device startup and phase separation process in this embodiment is as follows: a method combining pH regulation and kinetic control is adopted. The device inoculation sludge is the sludge from a winery in Henan that treats sodium citrate wastewater. The sludge has good properties and a high degree of granulation. First, the sludge is acclimated at HRT = 48 hours. After the device achieves stable COD removal and sulfate reduction effects, the influent OLR is improved by gradually shortening the HRT, and the HRT is shortened to 40 hours, 32 hours, 24 hours, 18 hours, 14 hours and 10 hours in turn. During the experiment, the pH of the acid-producing area 110 of the device was continuously detected. When the pH dropped to between 4.0 and 4.5, the pH was maintained in this range. If the pH is lower than 4.0, the concentration of sodium bicarbonate and sodium hydroxide (1:1) is increased in the influent to buffer the excess acidity of the acid-producing phase. At the same time, a sodium bicarbonate / sodium hydroxide solution containing 20 / 20 g / L is introduced into the methanogenic zone 120 through the pH adjustment port 340 to maintain the pH value of the methanogenic zone 120 at 7.5-8.5, thereby completing the two-phase separation of the acid-producing zone 110 and the methanogenic zone 120.

[0058] The first and second alloy catalyst zones 310 and 320 are equipped with porous alloy catalysts composed of 34.19% Cu, 33.35% Zn, 15.46% Co, 12.25% Ni, 2.72% Fe, and 2.03% Sn. The porous alloy catalysts are cylindrical, 8 cm in diameter and 40 cm long. Multiple channels are defined along the axis of the cylinder to increase the contact area between the catalyst and the water flow. When wastewater flows through the alloy catalyst at a constant flow rate, it releases free electrons into the wastewater, polarizing the fluid and neutralizing calcium and magnesium ions in the water. This alters the electrostatic potential of the water and prevents calcification of anaerobic sludge in the acid-generating zone 110 and the methane-generating zone 120.

[0059] The device and method of this embodiment were used to treat high-sulfate and high-calcium wastewater from a Henan food company. The system COD removal rate was over 90%, the sulfate reduction rate was 85%, and no sludge calcification occurred. Currently, no pipes or granular sludge need to be replaced after one year of operation.

[0060] Example 3

[0061] The basic content of the device structure of this embodiment is the same as that of Example 1, except that: in the treatment method of this embodiment, due to the low organic load of the influent, the pH value of the acid-generating zone 110 cannot be reduced to between 4.0 and 4.5 by the kinetic control method. Therefore, sulfuric acid needs to be added during the startup process to assist in adjusting the pH value of the acid-generating zone 110.

[0062] The target water treated in this example was wastewater from a papermaking enterprise in Nanjing, with a daily treatment capacity of 1500 t / d. COD, sulfate, and calcium ion concentrations were 1217 mg / L, 628 mg / L, and 1024 mg / L, respectively. Previously, the wastewater treatment process was plagued by severe sludge calcification and pipe scaling, requiring annual pipe and granular sludge replacement.

[0063] The device startup and phase separation process in this embodiment is as follows: a method combining pH regulation and kinetic control is adopted. The device inoculation sludge is the sludge from a winery in Jiangsu that treats sodium citrate wastewater. The sludge has good properties and a high degree of granulation. First, the sludge is acclimated at HRT = 36 hours. After the device achieves stable COD removal and sulfate reduction effects, the influent OLR is improved by gradually shortening the HRT, shortening the HRT to 24 hours, 16 hours, 12 hours, 8 hours and 6 hours in turn. During the experiment, the pH of the acid-producing zone 110 of the device is continuously monitored, and a certain amount of sulfuric acid is added to the influent to adjust the pH to between 4.0 and 4.5. At the same time, a sodium bicarbonate solution containing 20 g / L is introduced into the methane-producing zone 120 through the pH regulating port 340 to maintain the pH value of the methane-producing zone 120 at 6.8-7.5, thereby completing the two-phase separation of the acid-producing zone 110 and the methane-producing zone 120.

[0064] The first alloy catalyst zone 310 and the second alloy catalyst zone 320 are equipped with a porous alloy catalyst having the same elemental mass composition as in Example 2. The porous alloy catalyst is cylindrical, 8 cm in diameter and 10 cm long, with multiple channels along the axial direction of the alloy catalyst cylinder to increase the contact area between the catalyst and the water flow. This alloy catalyst material has the special function of releasing free electrons into the fluid medium and causing a polarization effect on the fluid medium. When wastewater flows through the alloy catalyst material at a certain flow rate, it can release free electrons into the wastewater, causing the fluid to polarize, neutralizing calcium and magnesium ions in the water, changing the electrostatic potential of the water, and preventing anaerobic sludge calcification in the acid-producing zone 110 and the methane-producing zone 120.

[0065] The device and method of this embodiment were used to treat wastewater from a papermaking enterprise in Nanjing. The system achieved a COD removal rate of over 90%, a sulfate reduction rate of 75%, and no sludge calcification. The system has been in operation for one and a half years without the need to replace pipes or granular sludge.

[0066] The above description is merely a partial embodiment of the present invention and does not constitute any formal or substantial limitation to the present invention. It should be noted that those skilled in the art may make several improvements and additions without departing from the method of the present invention, and such improvements and additions shall also be considered within the scope of protection of the present invention. Furthermore, any structural methods and embodiments similar to the technical solution devised without creative design without departing from the purpose of the present invention shall also fall within the scope of protection of the present invention.

Claims

1. A two-phase sulfate reduction device for preventing sludge calcification, comprising a device body (100), an internal circulation unit (200), and an alloy catalyst two-phase connection unit (300), characterized in that: An acid-generating zone (110), a methane-generating zone (120), and a precipitation zone (130) are arranged in the device body (100) from bottom to top. The volume ratio of the acid-generating zone (110), the methane-generating zone (120), and the precipitation zone (130) is 2:4:

1. An acid-generating zone three-phase separator (111) is arranged on the top of the acid-generating zone (110), and a methane-generating zone three-phase separator (121) is arranged between the methane-generating zone (120) and the precipitation zone (130). The internal circulation unit (200) comprises a cyclone gas-liquid separator (210), an exhaust pipe (220), an acid-producing zone riser pipe (230), a methane-producing zone riser pipe (240), and a return pipe (250); the cyclone gas-liquid separator (210) is arranged at the top of the device body (100); the exhaust pipe (220) is located at the top of the cyclone gas-liquid separator (210); the cyclone gas-liquid separator (210) is connected to the acid-producing zone three-phase separator (111) through the acid-producing zone riser pipe (230); the cyclone gas-liquid separator (210) is connected to the methane-producing zone three-phase separator (121) through the methane-producing zone riser pipe (240); and the cyclone gas-liquid separator (210) is connected to the methane-producing zone (120) through the return pipe (250); The alloy catalyst two-phase connection unit (300) comprises: a first alloy catalyst area (310), a second alloy catalyst area (320) and a U-shaped pipe (330); the first alloy catalyst area (310) is arranged in a water inlet pipe (101) connected below the device body (100); and the second alloy catalyst area (320) is arranged in the U-shaped pipe (330). The U-shaped pipe (330) is arranged on the side wall of the reactor body between the acid-generating zone (110) and the methane-generating zone (120); one end opening of the U-shaped pipe (330) is connected to the acid-generating zone (110), and the other end opening is connected to the methane-generating zone (120); the U-shaped pipe (330) connects the acid-generating zone (110) and the methane-generating zone (120); water effluent from the acid-generating zone (110) enters the methane-generating zone (120) through the U-shaped pipe; a baffle (400) is arranged between the acid-generating zone (110) and the methane-generating zone (120), and the baffle (400) is located between the two end openings of the U-shaped pipe; a pH adjustment port (340) is arranged on the side of the U-shaped pipe (330); the pH value of the acid-generating zone (110) is 4.0-4.5, and the pH value of the methane-generating zone (120) is 6.8-8.5; The first alloy catalyst zone (310) and the second alloy catalyst zone (320) are installed with a porous alloy catalyst material. The porous alloy catalyst material is a cylinder and is made of 30%-50% Zn, 15-35% Cu, 10%-30% Co, 5%-20% Ni, 0.5%-10% Fe and 0.1%-5% Sn by mass fraction. There are multiple channels along the axial direction of the alloy catalyst cylinder to increase the contact area between the catalyst and the water flow.

2. A two-phase sulfate reduction device for preventing sludge calcification according to claim 1, characterized in that: An overflow weir (131) is provided in the sedimentation area (130), a water outlet (132) is provided on the upper side of the sedimentation area (130), and the overflow weir (131) is located below the water outlet (132).

3. A two-phase sulfate reduction treatment method for preventing sludge calcification, characterized in that: The device according to any one of claims 1 to 2 is used for treatment, wherein the treatment method specifically comprises: S1. Anaerobic sludge is inoculated in the acid-producing area and the methane-producing area. Sulfate organic wastewater is introduced into the acid-producing area through the water inlet pipe at a flow rate of 1-5 m / s to contact the sludge to degrade organic matter in the wastewater. The sulfate organic wastewater flows through the first alloy catalyst area in the water inlet pipe and contacts the porous alloy catalyst material. The porous alloy catalyst material releases free electrons to the sulfate organic wastewater, neutralizing calcium and magnesium ions in the water body, changing the electrostatic potential of the water body, and preventing calcification of the anaerobic sludge in the acid-producing area. S2. The wastewater treated in the acid-generating zone is separated in the three-phase separator in the acid-generating zone. The sludge is retained and returned to the acid-generating zone. The generated gas enters the cyclone gas-liquid separator through the acid-generating zone riser. The effluent enters the methane-generating zone through a U-shaped pipe. Inside the U-shaped pipe, the effluent comes into contact with the porous alloy catalyst material in the second alloy catalyst zone. The porous alloy catalyst further prevents calcification of the anaerobic sludge in the methane-generating zone. S3, the effluent after the treatment in step S2 enters the methanogenic zone to further degrade the organic matter in the wastewater, the wastewater after the treatment in the methanogenic zone is separated in the three-phase separator of the methanogenic zone, the sludge is intercepted and returned to the methanogenic zone, the generated gas enters the cyclone gas-liquid separator through the riser pipe of the methanogenic zone, and the effluent is discharged after sedimentation in the sedimentation zone; S4. The gas generated in step S2 and step S3 carries the reaction mixture and enters the cyclone gas-liquid separator for gas-liquid separation. The gas is discharged through the exhaust pipe, and the liquid re-enters the methanogenic zone through the reflux pipe, thus realizing the internal circulation of the mixed liquid in the methanogenic zone. The first alloy catalyst zone or the second alloy catalyst zone is filled with a porous alloy catalyst material that is 1 / 200 of the effective volume of the device body.

4. A two-phase sulfate reduction treatment method for preventing sludge calcification according to claim 3, characterized in that: The pH value of the acid-generating zone is 4.0-4.5, and the ratio of sodium bicarbonate / COD in the influent is controlled at 1 / 10-1 / 50.

5. The two-phase sulfate reduction treatment method for preventing sludge calcification according to claim 3, characterized in that: The effluent discharged from step S3 is pH-adjusted and then mixed with the wastewater treated in the acid-producing area and fed into the methanogenic area to maintain the pH value of the methanogenic area at 6.8-8.5.

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