Sludge hydrothermal carbonization liquid pretreatment device

Abstract

The utility model relates to the technical field of sewage treatment, and discloses a sludge hydrothermal carbonization liquid pretreatment device which comprises a primary regulating tank, an expanded granular sludge bed, a coagulative precipitation tank, a deamination device and a secondary regulating tank which are communicated in sequence, the primary regulating tank is provided with a water inlet, the water inlet is communicated with a hydrothermal carbonization solution, the deamination device comprises a hollow fiber deamination membrane assembly, the hollow fiber deamination membrane assembly is provided with a deamination carbonization solution discharge port, and the input end of the secondary regulating tank is communicated with the deamination carbonization solution discharge port. The sludge hydrothermal carbonization liquid pretreatment device disclosed by the utility model can effectively reduce the concentration of nitrogen and phosphorus in the sludge hydrothermal carbonization liquid at the same time, particularly can effectively recover ammonia nitrogen, organic nitrogen and the like, reduces the loss of carbon, reduces the impact of a biochemical section of a sewage treatment plant, and ensures the stability and high efficiency of sewage treatment.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment technology, and in particular to a sludge hydrothermal carbonization liquid pretreatment device. Background Technology

[0002] With the rapid urbanization in my country, the amount of sludge discharged from wastewater treatment plants is increasing year by year. Hydrothermal carbonization is a rapidly developing new sludge treatment technology in recent years. Sludge treated by hydrothermal carbonization can yield good carbon materials, but the process generates liquid-phase products containing a large amount of organic matter and very high concentrations of carbon, nitrogen, and phosphorus. Improper treatment can cause secondary pollution. Low carbon-to-nitrogen ratios are common in urban wastewater in my country, thus requiring frequent carbon source replenishment during denitrification. Based on these considerations, by pre-treating the liquid-phase products of hydrothermal carbonization to reduce the concentration of nitrogen and phosphorus in the hydrothermal carbonization liquid, it can be used as a carbon source in the denitrification stage of wastewater treatment plants, achieving the resource utilization of excess sludge from wastewater treatment plants.

[0003] Currently, there are few reports on the pretreatment process of hydrothermal carbonization liquor from sludge. Patent application number 201810337696.5 provides a process for the resource utilization of residual hydrothermal carbonization liquor from sludge, mainly involving recovering nitrogen and phosphorus from the hydrothermal carbonization liquor using the struvite method, and then using it as a supplementary carbon source for biological denitrification. While this process recovers nitrogen and phosphorus from the hydrothermal carbonization liquor via the struvite method, it can only recover a small portion of ammonia nitrogen and is difficult to recover organic nitrogen from the liquor, and the carbon source is difficult to utilize effectively. Therefore, improving the recovery rate of nitrogen and phosphorus from hydrothermal carbonization liquor and enhancing the utilization of carbon sources, so that the carbon sources in the hydrothermal carbonization liquor can be fully recovered and utilized, is particularly important. Utility Model Content

[0004] In view of this, the present invention provides a sludge hydrothermal carbonization liquid pretreatment device to solve the problem that the existing sludge hydrothermal carbonization liquid pretreatment devices have low nitrogen and phosphorus recovery rates, resulting in low carbon source utilization.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] On one hand, this utility model provides a sludge hydrothermal carbonization liquid pretreatment device, including a primary equalization tank, an expanded granular sludge bed, a coagulation sedimentation tank, an ammonia removal device, and a secondary equalization tank connected in sequence; the primary equalization tank is provided with an inlet, which is connected to the hydrothermal carbonization liquid; the ammonia removal device includes a hollow fiber ammonia removal membrane assembly, which is provided with an ammonia removal carbonization liquid outlet; and the input end of the secondary equalization tank is connected to the ammonia removal carbonization liquid outlet.

[0007] Preferably, the sludge hydrothermal carbonization liquid pretreatment device further includes a filtration device, which includes a hollow fiber ultrafiltration membrane module; the filtration device is connected to the output end of the coagulation sedimentation tank, and the hollow fiber ultrafiltration membrane module is connected to the input end of the ammonia removal device.

[0008] Preferably, the expanded granular sludge bed is provided with a return water outlet and a drainage outlet; the return water outlet is connected to the inlet pipe through a return pump, and the inlet pipe is connected from the output end of the primary equalization tank to the expanded granular sludge bed; the drainage outlet is connected to the input end of the coagulation sedimentation tank.

[0009] Preferably, the filtration device further includes a first tank, and the hollow fiber ultrafiltration membrane assembly is disposed inside the first tank.

[0010] Preferably, the hollow fiber deammoniation membrane module has a pore size of 0.1-1.0 μm and is made of polytetrafluoroethylene.

[0011] Preferably, the ammonia removal device further includes a second tank, and the hollow fiber ultrafiltration membrane module is disposed inside the second tank.

[0012] Preferably, the hollow fiber ultrafiltration membrane module has a pore size of 0.01-10 μm, and the hollow fiber ultrafiltration membrane module is made of polyvinylidene fluoride or polytetrafluoroethylene.

[0013] Preferably, the sludge hydrothermal carbonization liquid pretreatment device further includes an ammonium sulfate solution tank, and the ammonia removal device is provided with an ammonium sulfate solution outlet, which is connected to the input end of the ammonium sulfate solution tank.

[0014] Preferably, the bottom of the primary equalization tank, the expanded granular sludge bed, and the coagulation sedimentation tank are all provided with sludge discharge outlets.

[0015] This utility model provides a sludge hydrothermal carbonization liquid pretreatment device, which has the following advantages compared with the prior art:

[0016] The sludge hydrothermal carbonization liquid pretreatment device of this invention can effectively reduce the nitrogen and phosphorus concentrations in the sludge hydrothermal carbonization liquid, especially for the effective recovery of ammonia nitrogen and organic nitrogen, thereby reducing carbon loss, reducing the impact on the biological treatment stage of the sewage treatment plant, and ensuring the stability and efficiency of sewage treatment. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the sludge hydrothermal carbonization liquid pretreatment device according to an embodiment of the present invention.

[0019] In the diagram: 1-Primary equalization tank, 2-Expanded granular sludge bed, 201-Influent pump, 202-Return pump, 203-Three-phase separator, 3-Coagulation sedimentation tank, 4-First tank body, 401-Hollow fiber ultrafiltration membrane module, 402-First effluent pump, 5-Second tank body, 501-Hollow fiber ammonia removal membrane module, 502-Second effluent pump, 6-Secondary equalization tank, 7-Ammonium sulfate solution tank. Detailed Implementation

[0020] The present invention will be described below through specific embodiments. Those skilled in the art will understand that the specific embodiments below are merely illustrative and do not limit the scope of the present invention in any way. Furthermore, in the following embodiments, unless otherwise specified, the reagents and equipment used are commercially available. If specific processing conditions and processes are not explicitly described in the later embodiments, conditions and processes known in the art can be used for processing.

[0021] In one aspect of this utility model, such as Figure 1 As shown, this utility model provides a sludge hydrothermal carbonization liquid pretreatment device, including a primary equalization tank 1, an expanded granular sludge bed 2, a coagulation sedimentation tank 3, an ammonia removal device, and a secondary equalization tank 6 connected in sequence; the primary equalization tank 1 is provided with an inlet, which is connected to the hydrothermal carbonization liquid; the ammonia removal device includes a hollow fiber ammonia removal membrane component 501, which is provided with an ammonia removal carbonization liquid outlet; the input end of the secondary equalization tank 6 is connected to the ammonia removal carbonization liquid outlet through a second effluent pump 502.

[0022] The sludge hydrothermal carbonization liquid pretreatment device of this invention can effectively reduce the nitrogen and phosphorus concentrations in the sludge hydrothermal carbonization liquid, especially for the effective recovery of ammonia nitrogen and organic nitrogen, thereby reducing the impact on the biological treatment stage of the sewage treatment plant and ensuring the stability and efficiency of sewage treatment.

[0023] In some embodiments of this utility model, the sludge hydrothermal carbonization liquid pretreatment device further includes a filtration device, which is connected to the output end of the coagulation sedimentation tank 3. The filtration device includes a hollow fiber ultrafiltration membrane module 401, which is connected to the input end of the deammoniation device via a first effluent pump 402. The hollow fiber ultrafiltration membrane module 401 is used to filter small particulate suspended solids in the hydrothermal carbonization liquid to prevent the subsequent deammoniation device from being affected by suspended solids and thus reducing the deammoniation efficiency.

[0024] In some embodiments of this utility model, the filtration device further includes a first pool body 4, and the hollow fiber ultrafiltration membrane assembly 401 is disposed within the first pool body 4. It is understood that the filtration device may contain only the hollow fiber ultrafiltration membrane assembly 401, i.e., the hollow fiber ultrafiltration membrane assembly 401 is an external design; or the filtration device may consist of the first pool body 4 and the hollow fiber ultrafiltration membrane assembly 401, i.e., the hollow fiber ultrafiltration membrane assembly 401 is a built-in design, and backwashing, etc., can be performed on the hollow fiber ultrafiltration membrane assembly 401 within the first pool body 4. No special limitations are imposed on this, and adjustments can be made according to actual conditions.

[0025] In some embodiments of this utility model, the hollow fiber ultrafiltration membrane module 401 is made of polyvinylidene fluoride or polytetrafluoroethylene. Polytetrafluoroethylene has the characteristics of low surface energy, resistance to sludge buildup, and good antifouling properties, and can filter wastewater with high concentrations of suspended solids. However, due to its relatively high material cost, when the concentration of suspended solids in the wastewater is low, the lower-cost polyvinylidene fluoride can be used. There is no specific limitation on this; adjustments can be made according to the actual situation.

[0026] In some embodiments of this utility model, the pore size of the hollow fiber ultrafiltration membrane module 401 is 0.01-10 μm, for example, it can be 0.01 μm, 0.05 μm, 1 μm, 2 μm, 5 μm, 8 μm, 10 μm, etc. The hollow fiber ultrafiltration membrane module 401 can be purchased commercially. The pore size of the hollow fiber ultrafiltration membrane module 401 can be adjusted according to the actual situation of suspended particles in the hydrothermal carbonization liquid, and there is no special limitation thereto.

[0027] The filtration device in this invention serves as a pretreatment for the ammonia removal process to prevent suspended solids from clogging the pores of the hollow fiber ammonia removal membrane assembly 501 and affecting the efficiency of free ammonia (NH3) permeating through the ammonia removal membrane and being absorbed by the sulfuric acid solution outside the membrane.

[0028] In some embodiments of this utility model, the expanded granular sludge bed 2 is provided with a three-phase separator 203 inside, and the exhaust port of the three-phase separator 203 is connected to a gas collection device; the expanded granular sludge bed 2 is provided with a return water outlet and a drainage outlet, wherein the drainage outlet is connected to the input end of the coagulation sedimentation tank 3, and the return water outlet is connected to the inlet pipe through a return pump 202. The inlet pipe is connected from the output end of the primary equalization tank 1 to the expanded granular sludge bed 2, and an inlet pump 201 is provided on the inlet pipe for pumping the wastewater in the primary equalization tank 1 to the expanded granular sludge bed 2.

[0029] Understandably, the hydrothermal carbonization liquid undergoes a hydrolysis and acidification reaction within the expanded granular sludge bed 2, which can convert organic nitrogen in the hydrothermal carbonization liquid into ammonia nitrogen, thereby increasing the conversion rate of organic nitrogen. It can also convert large molecular organic matter in the hydrothermal carbonization liquid into small molecular volatile fatty acids, reducing the loss of organic matter and increasing the yield. At the same time, it can improve the utilization rate of COD.

[0030] In some embodiments of this utility model, the ammonia removal device further includes a second tank 5, and the hollow fiber ammonia removal membrane assembly 501 is disposed within the second tank 5. It is understood that the ammonia removal device may contain only the hollow fiber ammonia removal membrane assembly 501, i.e., the hollow fiber ammonia removal membrane assembly 501 is an external design; or the ammonia removal device may consist of the second tank 5 and the hollow fiber ammonia removal membrane assembly 501, i.e., the hollow fiber ammonia removal membrane assembly 501 is an internal design. Backwashing of the hollow fiber ammonia removal membrane assembly 501 can be performed within the second tank 5. No special limitations are imposed on this, and adjustments can be made according to actual conditions.

[0031] The hollow fiber deammoniation membrane module 501 has a pore size of 0.1-1.0μm, for example, it can be 0.1μm, 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1.0μm, etc., and the hollow fiber deammoniation membrane module 501 is made of polytetrafluoroethylene.

[0032] Understandably, the hollow fiber ammonia removal membrane module 501 enables efficient absorption of ammonia nitrogen in the hydrothermal carbonization liquid. The hollow fiber ammonia removal membrane module 501 is commercially available. Generally, the smaller the pore size of the hollow fiber ammonia removal membrane module 501, the higher the selectivity and the better the ammonia separation effect. However, the permeability will decrease, the processing efficiency will be lower, and energy consumption will increase. The selection of the pore size of the hollow fiber ammonia removal membrane module 501 can be determined based on actual conditions, and no special limitations are imposed.

[0033] In some embodiments of this utility model, the sludge hydrothermal carbonization liquid pretreatment device further includes an ammonium sulfate solution tank 7, and the ammonia removal device is provided with an ammonium sulfate solution outlet, which is connected to the input end of the ammonium sulfate solution tank 7. In the hollow fiber ammonia removal membrane module 501, sulfuric acid is used to absorb the ammonia removed by the hollow fiber ammonia removal membrane module 501 and generate ammonium sulfate. The generated ammonium sulfate is transported to the ammonium sulfate solution tank 7 for storage and reuse, for example, it can be crystallized and reused as nitrogen fertilizer.

[0034] In some embodiments of this utility model, the bottom of the primary equalization tank 1, the expanded granular sludge bed 2, and the coagulation sedimentation tank 3 are all provided with sludge discharge outlets. All sludge discharge outlets are connected to a sludge discharge pipe. The discharged sludge can continue to undergo hydrothermal carbonization treatment. As a result, the carbon loss of the hydrothermal carbonization liquid of the sludge treated by the pretreatment device of this utility model is small, realizing the efficient recovery and reuse of carbon source in the hydrothermal carbonization liquid of the sludge.

[0035] In another aspect, this utility model also provides a pretreatment process for sludge hydrothermal carbonization liquid, comprising the following steps:

[0036] (1) The hydrothermal carbonization liquid is transported to the primary conditioning tank and the pH value is adjusted to obtain the initial carbonization liquid;

[0037] (2) The initial carbonized liquid is transported to the expanded granular sludge bed for hydrolysis and acidification reaction to obtain hydrolysis and acidification carbonized liquid;

[0038] (3) The hydrolyzed acidified carbonized liquid is transported to a coagulation sedimentation tank, and water treatment agents are added to remove phosphorus and flocculate sedimentation to obtain phosphorus-removed carbonized liquid.

[0039] (4) The phosphorus removal carbonization liquid is transported to the deammoniation device for deammoniation treatment to obtain deammoniation carbonization liquid and ammonium sulfate solution;

[0040] (5) Discharge the deammoniation carbonized liquid into the secondary conditioning tank and adjust the pH value to neutral to obtain the secondary conditioning carbonized liquid.

[0041] In some embodiments of this utility model, the hydrothermal carbonization liquid is transported to a primary conditioning tank to adjust the pH value and obtain a pre-conditioned carbonization liquid.

[0042] Optionally, adjusting the pH value to 4.5-5.5, such as 4.5, 5.0, or 5.5, is acceptable. It should be noted that the hydrothermal carbonization liquid is the filtrate after sludge has undergone sulfuric acid carbonization and filter press treatment. Its pH value is around 4, and some sludge remains. Adjusting the pH to 4.5-5.5 by adding alkali ensures that the pH value for the subsequent hydrolysis and acidification reaction within the expanded granular sludge bed is within a suitable range, and also allows the remaining solid residue in the hydrothermal carbonization liquid to initially settle. The pH value can be adjusted by adding waste alkalis such as waste sodium hydroxide or waste sodium bicarbonate, or conventional alkaline solutions such as sodium hydroxide, sodium bicarbonate, calcium hydroxide, or sodium carbonate.

[0043] In some embodiments of this utility model, the initial carbonized liquid is transported to an expanded granular sludge bed for hydrolysis and acidification reaction to obtain hydrolyzed acidified carbonized liquid.

[0044] Understandably, the suitable pH value for the hydrolysis acidification reaction is 5.5-6.5. During the normal operation of the expanded granular sludge bed, more than 80% of the organic nitrogen in the hydrothermal carbonization liquid is converted into ammonia nitrogen. This process produces alkaline substances, and the pH value will increase by about 1 accordingly. Therefore, adjusting the initial pH value of the carbonization liquid to 4.5-5.5 can ensure the smooth progress of the hydrolysis acidification reaction in the expanded granular sludge bed.

[0045] This invention, by transporting the initial-conditioning carbonized liquid to an expanded granular sludge bed for hydrolysis and acidification, converts organic nitrogen in the hydrothermal carbonized liquid into ammonia nitrogen, thereby increasing the conversion rate of organic nitrogen. Furthermore, it converts large-molecule organic matter in the hydrothermal carbonized liquid into small-molecule volatile fatty acids, improving the utilization rate of COD in the hydrothermal carbonized sludge. Experimental studies have shown that without treatment by the expanded granular sludge bed, less than 50% of the COD in the hydrothermal carbonized liquid is available for denitrification in wastewater treatment. However, after treatment with the expanded granular sludge bed, the COD available for denitrification can be increased to approximately 70%, effectively improving the utilization rate of carbon sources in the hydrothermal carbonized liquid.

[0046] Optionally, the hydraulic retention time of the expanded granular sludge bed is 12-24 hours, such as 12 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, etc. A longer hydraulic retention time increases COD availability, but also leads to a decrease in COD content. Within the hydraulic retention time range specified in this invention, both COD availability and COD content achieve good results.

[0047] Optionally, the hydrolysis-acidification reaction temperature is 25-45℃, for example, 25℃, 30℃, 35℃, 40℃, 45℃, etc. As the temperature increases, the reaction process accelerates, and the COD availability and organic nitrogen conversion rate will increase accordingly. The reaction time is adjusted according to the reaction temperature. For example, it may take 12 hours when the reaction temperature is 45℃, and 16 hours when the reaction temperature is 30℃. There is no special limitation on this, and it can be adjusted according to the actual situation.

[0048] Optionally, the pH value of the hydrolysis acidification reaction is 5.5-6.5. Since the reaction is in a constantly changing process, it is difficult to completely and accurately control the conditions inside the expanded sludge granular bed. Therefore, the pH value is set to a range within which good treatment results can be achieved.

[0049] Optionally, the internal recirculation ratio of the expanded granular sludge bed is 10-50, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50, etc. A higher internal recirculation ratio results in better mixing within the expanded granular sludge bed and better treatment of the hydrothermal carbonization liquid of the sludge. However, a higher internal recirculation ratio also leads to higher power costs. Therefore, there is no specific limitation on the internal recirculation ratio, and it can be selected according to actual needs.

[0050] In some embodiments of this utility model, the hydrolyzed acidified carbonized liquid is transported to a coagulation sedimentation tank, and water treatment agents are added for phosphorus removal and flocculation sedimentation to obtain a phosphorus-removed carbonized liquid.

[0051] Optionally, the water treatment agent is polyaluminum chloride and polyacrylamide. The amount of polyaluminum chloride added is 10-20 times the phosphorus mass content in the hydrolyzed acidified carbonized liquid. Preferably, the effective concentration of polyaluminum chloride can be 30%. If the effective concentration of polyaluminum chloride decreases, the dosage should be increased accordingly. Optionally, based on the volume of the hydrolyzed acidified carbonized liquid, the dosage concentration of polyacrylamide is 0.5-2 mg / L, for example, 0.5 mg / L, 1.0 mg / L, 1.5 mg / L, 2.0 mg / L, etc. Polyaluminum chloride acts on the water to quickly form primary flocs, and polyacrylamide can further promote the aggregation and growth of these primary flocs, forming more stable and easily separated large flocs. The synergistic effect of the two improves the coagulation efficiency of the hydrothermal carbonized liquid, enhances the removal capacity of suspended solids, colloids and other impurities, and more effectively removes phosphate ions, preventing them from polluting the water.

[0052] In some embodiments of this utility model, step (3) further includes the following process: the phosphorus removal carbonization liquid is transported to a filtration device for filtration, and small particulate suspended matter in the wastewater is filtered by a hollow fiber ultra-microfiltration membrane module in the filtration device to prevent the ammonia removal efficiency of the ammonia removal device from being affected by the suspended matter.

[0053] In some embodiments of this utility model, the phosphorus removal carbonization liquid is transported to a deammoniation device for deammoniation treatment to obtain a deammoniation carbonization liquid and ammonium sulfate solution.

[0054] The principle of ammonia removal via hollow fiber membrane modules in a deammoniation unit is to convert ammonium ions into free ammonia. Based on the principle of membrane contact reactors, the deammoniation membrane serves as the mass transfer interface. Alkali is added to convert ammonium ions (NH4+) in the phosphorus removal carbonization solution into free ammonia. + It is converted into free ammonia (NH3), and NH3 is absorbed by the sulfuric acid solution outside the membrane through the deammoniation membrane to form ammonium sulfate solution.

[0055] Optionally, during the deammoniation process, the pH value of the phosphorus removal carbonization liquid is adjusted to 9-13 before deammoniation treatment, for example, it can be 9, 10, 11, 12, 13, etc. When the pH is 9-13, the ammonium ions in the hydrothermal carbonization liquid will be more easily converted into free gaseous ammonia, which will then be more easily absorbed into the absorption liquid through the micropores of the hollow fiber deammoniation membrane module, thereby improving the deammoniation effect.

[0056] Ammonia removal treatment can completely remove ammonia nitrogen from the hydrothermal carbonization liquid of sludge, as well as ammonia nitrogen converted from organic nitrogen. This not only increases the C / N ratio of the hydrothermal carbonization liquid of sludge, but also reduces the side effects of nitrogen on wastewater treatment plants.

[0057] In some embodiments of this utility model, the deammoniation carbonized liquid is discharged to a secondary conditioning tank to adjust the pH value to neutral, thereby obtaining a secondary conditioning carbonized liquid.

[0058] Optionally, after adjusting the pH of the hydrothermal carbonized liquid in the secondary equalization tank to around 7 by adding an acidic solution, it can be added to the anaerobic or anoxic section of the wastewater treatment plant to supplement the carbon source.

[0059] In some embodiments of this invention, the ammonium sulfate solution generated in step (4) is transported to an ammonium sulfate solution tank for crystallization to obtain ammonium sulfate. The crystallized ammonium sulfate can be reused, for example, as a nitrogen fertilizer to effectively recover nitrogen from the hydrothermal carbonization liquid of sludge.

[0060] The technical solutions of this utility model will be clearly and completely described below with reference to specific embodiments. The embodiments of this application are only examples, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0061] The sludge hydrothermal carbonization liquid pretreatment device used in the following embodiments is as follows: Figure 1 As shown, it includes a primary equalization tank 1, an expanded granular sludge bed 2, a coagulation sedimentation tank 3, a filtration device, an ammonia removal device, and a secondary equalization tank 6, which are connected in sequence.

[0062] The primary equalization tank 1 is equipped with an inlet that is connected to the hydrothermal carbonization liquid. The expanded granular sludge bed 2 has a three-phase separator 203 inside, with its exhaust port connected to a gas collection device. The expanded granular sludge bed 2 is equipped with a return water outlet and a drainage outlet. The drainage outlet is connected to the input end of the coagulation sedimentation tank 3. The return water outlet is connected to the inlet pipe via a return pump 202. The inlet pipe connects to the expanded granular sludge bed 2 from the output end of the primary equalization tank 1, and is equipped with an inlet pump 201. Filtration... The device includes a first tank 4 and a hollow fiber ultrafiltration membrane module 401. The filtration device is connected to the output end of the coagulation sedimentation tank 3, and the hollow fiber ultrafiltration membrane module 401 is connected to the input end of the deammoniation device through a first effluent pump 402. The deammoniation device includes a second tank 5 and a hollow fiber deammoniation membrane module 501. The input end of the secondary equalization tank 6 is connected to the outlet of the hollow fiber deammoniation membrane module 501 through a second effluent pump 502. The deammoniation device is equipped with an ammonium sulfate solution outlet, which is connected to an ammonium sulfate solution tank 7.

[0063] Example 1

[0064] This embodiment provides a pretreatment process for sludge hydrothermal carbonization liquid, the specific steps of which are as follows:

[0065] (1) After pumping the residual sludge hydrothermal carbonization liquid from the municipal wastewater treatment plant into the primary equalization tank, waste alkali is added to adjust the pH to 5.5 to obtain the initial carbonization liquid.

[0066] (2) The initial carbonized liquid is pumped into the expanded granular sludge bed by the inlet pump to carry out hydrolysis and acidification reaction to obtain hydrolysis and acidification carbonized liquid. The hydraulic retention time of the expanded granular sludge bed is 12h, the temperature is 25℃, the pH is 6.5, and the internal reflux ratio is 10.

[0067] (3) The hydrolyzed acidified carbonized liquid is transported to the coagulation sedimentation tank, and polyaluminum chloride is added at 900 mg / L (about 10 times the phosphorus content in the hydrolyzed acidified carbonized liquid), and polyacrylamide is added at 0.5 mg / L to remove phosphorus and sludge flocculation and sedimentation, so as to obtain phosphorus-removed carbonized liquid.

[0068] (4) The phosphorus removal carbonization liquid is transported to the filtration device. After the small particulate suspended matter is filtered by the 10μm PVDF hollow fiber ultra-microfiltration membrane module, it enters the deammoniation device through the water outlet pump.

[0069] (5) After adding alkali to the wastewater of the deammoniation unit to adjust the pH to 9, the wastewater is treated by a 1.0μm PTFF deammoniation unit. Then, sulfuric acid is added to absorb the ammonia removed by the deammoniation unit, resulting in deammoniation carbonized liquid and ammonium sulfate solution. The ammonium sulfate solution is transported to the ammonium sulfate solution pool for storage.

[0070] (6) The deammoniation carbonized liquid is discharged to the secondary equalization tank via the effluent pump. After adding acid to adjust the pH to 6.8, the secondary equalization carbonized liquid is obtained. The secondary equalization carbonized liquid is added to the anaerobic section of the sewage treatment plant to supplement the carbon source.

[0071] The concentrations of COD, ammonia nitrogen, organic nitrogen, and total phosphorus in the hydrothermal carbonization liquid of the municipal wastewater treatment plant before and after pretreatment in this embodiment were measured, and the results are shown in Table 1.

[0072] Table 1

[0073] index COD (carbon source) ammonia nitrogen Organic nitrogen Total phosphorus Total nitrogen Before pretreatment (mg / L) 33128 1258 1324 90.7 2702 After pretreatment (mg / L) 29824 259 278 45.2 649 Removal rate / % 9.91 79.41 79 50.17 75.98

[0074] Example 2

[0075] This embodiment provides a pretreatment process for sludge hydrothermal carbonization liquid, the specific steps of which are as follows:

[0076] (1) After pumping the residual sludge hydrothermal carbonization liquid from the brewing wastewater treatment plant into the primary conditioning tank, waste alkali is added to adjust the pH to 4.5 to obtain the initial carbonization liquid.

[0077] (2) The initial carbonized liquid is pumped into the expanded granular sludge bed by the inlet pump to carry out hydrolysis and acidification reaction to obtain hydrolysis and acidification carbonized liquid. The hydraulic retention time of the expanded granular sludge bed is 16h, the temperature is 30℃, the pH is 5.5, and the internal reflux ratio is 20.

[0078] (3) The hydrolyzed acidified carbonized liquid is transported to the coagulation sedimentation tank, and polyaluminum chloride is added at 2800 mg / L (about 20 times the amount of hydrolyzed acidified carbonized liquid), and polyacrylamide is added at 1 mg / L to remove phosphorus and sludge flocculation and sedimentation, so as to obtain phosphorus-removed carbonized liquid.

[0079] (4) The wastewater after coagulation and sedimentation is transported to the filtration device. After the small particulate suspended matter is filtered by the 1μm PVDF hollow fiber ultra-microfiltration membrane module, it enters the deammoniation device through the effluent pump.

[0080] (5) After adding alkali to the wastewater of the deammoniation unit to adjust the pH to 9, the wastewater is treated by a 0.5μm PTFF deammoniation unit. Then, sulfuric acid is added to absorb the ammonia removed by the deammoniation unit, resulting in deammoniation carbonized liquid and ammonium sulfate solution. The ammonium sulfate solution is transported to the ammonium sulfate solution pool for storage.

[0081] (6) The deammoniation carbonization liquid is discharged to the secondary equalization tank via the effluent pump. After adding acid to adjust the pH to 7.0, the secondary equalization carbonization liquid is obtained. The secondary equalization carbonization liquid is added to the anoxic section of the sewage treatment plant to supplement the carbon source.

[0082] The concentrations of COD, ammonia nitrogen, organic nitrogen, and total phosphorus in the hydrothermal carbonization liquid of the wastewater from the brewing wastewater treatment plant in this embodiment were measured before and after treatment, and the results are shown in Table 2.

[0083] Table 2

[0084] index COD (carbon source) ammonia nitrogen Organic nitrogen Total phosphorus Total nitrogen Before pretreatment (mg / L) 96243 1862 1622 138 3680 After pretreatment (mg / L) 93468 363 264 68 809 Removal rate / % 2.88 80.50 83.72 50.72 78.01

[0085] Example 3

[0086] This embodiment provides a pretreatment process for sludge hydrothermal carbonization liquid, the specific steps of which are as follows:

[0087] (1) After pumping the residual sludge hydrothermal carbonization liquid from the pharmaceutical wastewater treatment plant into the primary conditioning tank, waste alkali is added to adjust the pH to 5 to obtain the initial carbonization liquid.

[0088] (2) The initial carbonized liquid is pumped into the expanded granular sludge bed by the inlet pump to carry out hydrolysis and acidification reaction to obtain hydrolysis and acidification carbonized liquid. The hydraulic retention time of the expanded granular sludge bed is 24h, the temperature is 45℃, the pH is 6, and the internal reflux ratio is 50.

[0089] (3) The hydrolyzed acidified carbonized liquid is transported to the coagulation sedimentation tank, and polyaluminum chloride is added at 4200 mg / L (about 15 times the amount of hydrolyzed acidified carbonized liquid), and polyacrylamide is added at 2 mg / L to remove phosphorus and sludge flocculation and sedimentation, so as to obtain phosphorus-removed carbonized liquid.

[0090] (4) The wastewater in the coagulation sedimentation is transported to the filtration device, and after the small particulate suspended matter is filtered by the 0.01μmPTFF hollow fiber ultra-microfiltration membrane module, it enters the deammoniation device through the effluent pump.

[0091] (5) After adjusting the pH to 9 by adding alkali to the wastewater of the deammoniation unit, the wastewater is treated by two-stage 0.1μmPTFF deammoniation units. Then, sulfuric acid is added to absorb the ammonia removed by the deammoniation unit, resulting in deammoniation carbonized liquid and ammonium sulfate solution. The ammonium sulfate solution is transported to the ammonium sulfate solution pool for storage.

[0092] (6) The deammoniation carbonization liquid is discharged to the secondary equalization tank via the effluent pump. After adding acid to adjust the pH to 7.2, the secondary equalization carbonization liquid is obtained. The secondary equalization carbonization liquid is added to the anaerobic section of the sewage treatment plant to supplement the carbon source.

[0093] The concentrations of COD, ammonia nitrogen, organic nitrogen, and total phosphorus in the residual sludge hydrothermal carbonization liquid of the pharmaceutical wastewater treatment plant in this embodiment were measured before and after pretreatment, and the results are shown in Table 3.

[0094] Table 3

[0095] index COD (carbon source) ammonia nitrogen Organic nitrogen Total phosphorus Total nitrogen Before pretreatment (mg / L) 105613 3824 3934 286 8006 After pretreatment (mg / L) 98568 174 238 76 648 Removal rate / % 6.67 95.44 93.95 73.43 91.9

[0096] In Examples 1-3, Example 1 deals with hydrothermal carbonization liquid from wastewater treatment plant sludge, where the concentrations of various pollutants are relatively low. Example 2 deals with hydrothermal carbonization liquid from wastewater treatment plant sludge, where the nitrogen and phosphorus concentrations are moderate and the total COD concentration is high, but the proportion of recalcitrant COD is relatively low. Example 3 deals with hydrothermal carbonization liquid from wastewater treatment plant sludge, where the total concentrations of nitrogen, phosphorus, and COD are all high, and the proportion of recalcitrant COD is also high. Based on the different pollutant concentrations in the hydrothermal carbonization liquids, Examples 1-3 used lower, medium, and higher values ​​for the parameters of the expanded granular sludge bed, the amount of water treatment agent added, and the membrane pore size, respectively. Furthermore, because the parameter values ​​differ in each process step, the treatment effects on nitrogen, phosphorus, and COD are also different.

[0097] In summary, the sludge hydrothermal carbonization liquid pretreatment device of this invention can effectively reduce nitrogen and phosphorus in the sludge hydrothermal carbonization liquid. It can not only effectively reduce the concentration of ammonia nitrogen, but also effectively reduce the concentration of organic nitrogen, reduce the impact on the biological treatment section of the sewage treatment plant, and ensure the stability and efficiency of sewage treatment.

[0098] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A sludge hydrothermal carbonization liquid pretreatment device, characterized in that, The device comprises a primary regulating pool, an expanded granular sludge bed, a coagulation and sedimentation pool, a deamination device and a secondary regulating pool connected in sequence.

2. The sludge hydrocarbonization liquid pretreatment device according to claim 1, characterized by, The device further comprises a filter device connected to the output end of the coagulation and sedimentation pool.

3. The sludge hydrocarbonization liquid pretreatment device according to claim 2, characterized in that, The filter device further comprises a first pool body, and the hollow fiber ultra-microfiltration membrane assembly is arranged in the first pool body.

4. The sludge hydrocarbonization liquid pretreatment device according to claim 2, characterized by, The pore size of the hollow fiber deamination membrane assembly is 0.1-1.0 μm, and the material of the hollow fiber deamination membrane assembly is polytetrafluoroethylene.

5. The sludge hydrocarbonization liquid pretreatment device according to claim 1, characterized by, The expanded granular sludge bed is provided with a backflow water outlet and a drainage outlet. The backflow water outlet is connected to the water inlet pipe through a backflow pump, and the water inlet pipe is connected to the expanded granular sludge bed from the output end of the primary regulating pool. The drainage outlet is connected to the input end of the coagulation and sedimentation pool.

6. The sludge hydrocarbonization liquid pretreatment device according to claim 2, characterized by, The pore size of the hollow fiber ultra-microfiltration membrane assembly is 0.01-10 μm, and the material of the hollow fiber ultra-microfiltration membrane assembly is polyvinylidene fluoride or polytetrafluoroethylene.

7. The sludge hydrocarbonization liquid pretreatment device according to claim 2, characterized by, The deamination device further comprises a second pool body, and the hollow fiber ultra-microfiltration membrane assembly is arranged in the second pool body.

8. The sludge hydrocarbonization liquid pretreatment device according to any one of claims 1-6, characterized in that, The device further comprises an ammonium sulfate solution pool, and the deamination device is provided with an ammonium sulfate solution outlet connected to the input end of the ammonium sulfate solution pool.

9. The sludge hydrocarbonization liquid pretreatment device according to any one of claims 1-6, characterized in that, The bottom of the primary regulating pool, the expanded granular sludge bed and the coagulation and sedimentation pool is provided with a sludge discharge port.

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