Sludge hydrothermal carbonization liquid pretreatment device and process

Abstract

The invention relates to the technical field of sewage treatment, and discloses a sludge hydrothermal carbonization liquid pretreatment device and process, the sludge hydrothermal carbonization liquid pretreatment device comprises a primary adjusting tank, an expanded granular sludge bed, a coagulative precipitation tank, a deamination device and a secondary adjusting 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. According to the sludge hydrothermal carbonization liquid pretreatment device and process, the nitrogen and phosphorus concentration in the sludge hydrothermal carbonization liquid can be effectively reduced at the same time, particularly, ammonia nitrogen, organic nitrogen and the like can be effectively recovered, the carbon loss is reduced, the impact of a biochemical section of a sewage treatment plant is reduced, and the stability and high efficiency of sewage treatment are ensured.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to a sludge hydrothermal carbonization liquid pretreatment device and process. Background Art

[0002] With the rapid development of urbanization, the amount of sludge discharged from sewage treatment plants has increased year by year. Hydrothermal carbonization is a new type of sludge treatment technology that has developed rapidly in recent years. After hydrothermal carbonization, sludge can obtain good carbon materials, but liquid products will be produced during the treatment process, which contain a large amount of organic matter and have very high carbon, nitrogen and phosphorus concentrations. Improper treatment will cause secondary pollution. The low carbon-nitrogen ratio of urban sewage is common, so carbon sources are often required in the denitrification process. Based on the above situation, by pre-treating the hydrothermal carbonization liquid product in advance and reducing the concentration of nitrogen and phosphorus in the hydrothermal carbonization liquid, it can be used as a carbon source in the denitrification stage of the sewage treatment plant to realize the resource utilization of the residual sludge in the sewage treatment plant.

[0003] At present, there are few reports on the process of pretreatment of sludge hydrothermal carbonized liquid. The patent with application number 201810337696.5 provides a process for resource utilization of residual sludge hydrothermal carbonized liquid, which mainly recovers nitrogen and phosphorus from the hydrothermal carbonized liquid through the struvite method and uses it as a carbon source supplement for biological denitrification. This process recovers nitrogen and phosphorus in the hydrothermal carbonized liquid through the struvite method, but the struvite method can only recover a small part of ammonia nitrogen, and it is difficult to recover organic nitrogen in the hydrothermal carbonized liquid, and the carbon source therein is difficult to effectively utilize. Therefore, it is particularly important to improve the recovery rate of nitrogen and phosphorus in the hydrothermal carbonized liquid and improve the utilization of carbon sources so that the carbon source in the hydrothermal carbonized liquid can be fully recycled. Summary of the invention

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

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] On the one hand, the present invention provides a sludge hydrothermal carbonized liquid pretreatment device, comprising a primary regulating tank, an expanded granular sludge bed, a coagulation sedimentation tank, a deammonification device and a secondary regulating tank which are connected in sequence; the primary regulating tank is provided with a water inlet, which is connected to the hydrothermal carbonized liquid; the deammonification device comprises a hollow fiber deammonification membrane assembly, which is provided with a deammonification carbonized liquid discharge outlet; the input end of the secondary regulating tank is connected to the deammonification carbonized liquid discharge outlet.

[0007] Preferably, the sludge hydrothermal carbonized liquid pretreatment device also includes a filtering device, which includes a hollow fiber ultrafiltration membrane assembly; the filtering device is connected to the output end of the coagulation sedimentation tank, and the hollow fiber ultrafiltration membrane assembly is connected to the input end of the deammoniation device.

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

[0009] Preferably, 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.

[0010] Preferably, 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.

[0011] Preferably, the sludge hydrothermal carbonized liquid pretreatment device further comprises an ammonium sulfate solution pool, and the deammoniation device is provided with an ammonium sulfate solution outlet, and the ammonium sulfate solution outlet is connected to the input end of the ammonium sulfate solution pool.

[0012] Preferably, the bottoms of the primary regulating tank, the expanded granular sludge bed and the coagulation sedimentation tank are all provided with sludge discharge ports.

[0013] On the other hand, the present invention also provides a sludge hydrothermal carbonization liquid pretreatment process, comprising the following steps:

[0014] (1) transporting the hydrothermal carbonized liquid to a primary regulating tank to adjust the pH value to obtain a primary adjusted carbonized liquid;

[0015] (2) transporting the initially adjusted carbonized liquid to an expanded granular sludge bed for hydrolysis and acidification to obtain a hydrolysis and acidification carbonized liquid;

[0016] (3) transporting the hydrolyzed acidified carbonized liquid to a coagulation sedimentation tank, adding a water treatment agent to perform phosphorus removal and flocculation sedimentation to obtain a phosphorus-removed carbonized liquid;

[0017] (4) transporting the dephosphorization carbonized liquid to a deammoniation device for deammoniation treatment to obtain a deammoniation carbonized liquid and an ammonium sulfate solution;

[0018] (5) Discharging the deammoniation carbonized liquid into a secondary regulating tank, adjusting the pH value to neutral, and obtaining a secondary carbonized liquid.

[0019] Preferably, step (3) further comprises the following process: conveying the dephosphorization carbonization liquid to a filtering device for removing suspended matter.

[0020] Preferably, the hydraulic retention time of the expanded granular sludge bed in step (2) is 12-24 hours, the temperature is 25-45° C., the pH value is 5.5-6.5, and the internal reflux ratio is 10-50.

[0021] Preferably, the water treatment agents are polyaluminium chloride and polyacrylamide, the amount of polyaluminium chloride added is 10-20 times the mass content of phosphorus in the hydrolysis acidification carbonization liquid, and the concentration of polyacrylamide added is 0.5-2 mg / L.

[0022] Preferably, the method further comprises the following steps: transporting the ammonium sulfate solution to an ammonium sulfate solution pool for crystallization to obtain ammonium sulfate.

[0023] The present invention provides a sludge hydrothermal carbonization liquid pretreatment device and process, which has the following beneficial effects compared with the prior art:

[0024] The sludge hydrothermal carbonized liquid pretreatment device and process of the present invention can effectively reduce the nitrogen and phosphorus concentrations in the sludge hydrothermal carbonized liquid at the same time, especially can effectively recover ammonia nitrogen, organic nitrogen, etc., reduce carbon loss, reduce the impact of the biochemical section of the sewage treatment plant, and ensure the stability and efficiency of sewage treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0026] Figure 1 It is a schematic diagram of a sludge hydrothermal carbonization liquid pretreatment device according to an embodiment of the present invention.

[0027] In the figure: 1-primary regulating tank, 2-expanded granular sludge bed, 201-water inlet pump, 202-reflux pump, 203-three-phase separator, 3-coagulation sedimentation tank, 4-first tank body, 401-hollow fiber ultrafiltration membrane assembly, 402-first effluent pump, 5-second tank body, 501-hollow fiber deammoniation membrane assembly, 502-second effluent pump, 6-secondary regulating tank, 7-ammonium sulfate solution tank. DETAILED DESCRIPTION

[0028] The present invention will be described below by specific embodiment, and it will be appreciated by those skilled in the art that the following specific embodiment is only for illustrative purposes, and does not limit the scope of the present invention in any way. In addition, in the following embodiments, unless otherwise specified, the reagent and equipment used are all commercially available. If in the following embodiments, specific treatment conditions and treatment process are not clearly described, then conditions and processes known in the art can be adopted to process.

[0029] In one aspect of the present invention, Figure 1 As shown, the present invention provides a sludge hydrothermal carbonized liquid pretreatment device, comprising a primary regulating tank 1, an expanded granular sludge bed 2, a coagulation sedimentation tank 3, a deammonification device and a secondary regulating tank 6 which are connected in sequence; the primary regulating tank 1 is provided with a water inlet which is communicated with the hydrothermal carbonized liquid, the deammonification device comprises a hollow fiber deammonification membrane assembly 501, the hollow fiber deammonification membrane assembly 501 is provided with a deammonification carbonized liquid discharge outlet, and the input end of the secondary regulating tank 6 is communicated with the deammonification carbonized liquid discharge outlet via a second water outlet pump 502.

[0030] The sludge hydrothermal carbonized liquid pretreatment device and process of the present invention can effectively reduce the nitrogen and phosphorus concentrations in the sludge hydrothermal carbonized liquid at the same time, especially can effectively recover ammonia nitrogen, organic nitrogen, etc., reduce the impact of the biochemical section of the sewage treatment plant, and ensure the stability and efficiency of sewage treatment.

[0031] In some embodiments of the present invention, the sludge hydrothermal carbonized liquid pretreatment device further includes a filtering device, the filtering device is connected to the output end of the coagulation sedimentation tank 3, and the hollow fiber ultra-microfiltration membrane assembly 401 of the filtering device is connected to the input end of the deamination device through the first outlet pump 402. Among them, the hollow fiber ultra-microfiltration membrane assembly 401 is used to filter small suspended particles in the hydrothermal carbonized liquid to prevent the subsequent deamination device from being affected by the suspended matter and reducing the deamination efficiency.

[0032] In some embodiments of the present invention, the filtration device further includes a first tank body 4, and the hollow fiber ultra-microfiltration membrane assembly 401 is disposed in the first tank body 4. It can be understood that the filtration device may only contain the hollow fiber ultra-microfiltration membrane assembly 401, that is, the hollow fiber ultra-microfiltration membrane assembly 401 is an external design; or the filtration device is composed of the first tank body 4 and the hollow fiber ultra-microfiltration membrane assembly 401, that is, the hollow fiber ultra-microfiltration membrane assembly 401 is a built-in design, and the hollow fiber ultra-microfiltration membrane assembly 401 can be backwashed in the first tank body 4, etc., and there is no special limitation on this, and it can be adjusted according to actual conditions.

[0033] In some embodiments of the present invention, the hollow fiber ultra-microfiltration membrane assembly 401 is made of polyvinylidene fluoride or polytetrafluoroethylene. Among them, polytetrafluoroethylene has the characteristics of low surface energy, not easy to hang mud, and good anti-fouling performance, and can filter high-concentration suspended wastewater, but because the material cost is relatively high, when the concentration of suspended matter in the wastewater is low, polyvinylidene fluoride with lower cost can be used. There is no special limitation on this, and it can be adjusted according to actual conditions.

[0034] In some embodiments of the present invention, the pore size of the hollow fiber ultra-microfiltration membrane assembly 401 is 0.01-10 μm, for example, 0.01 μm, 0.05 μm, 1 μm, 2 μm, 5 μm, 8 μm, 10 μm, etc. The hollow fiber ultra-microfiltration membrane assembly 401 can be purchased from the market, and the pore size of the hollow fiber ultra-microfiltration membrane assembly 401 can be adjusted according to the actual situation of the suspended particles in the hydrothermal carbonization liquid, and there is no special limitation on this.

[0035] The filtration device in the present invention is used as a pre-treatment for the deamination process to prevent suspended matter from clogging the pores of the hollow fiber deamination membrane assembly 501 and affecting the free ammonia (NH 3 )The efficiency of being absorbed by the sulfuric acid solution outside the membrane through the deammoniation membrane.

[0036] In some embodiments of the present invention, a three-phase separator 203 is provided inside the expanded granular sludge bed 2, and the exhaust port of the three-phase separator 203 is connected to the gas collection device; the expanded granular sludge bed 2 is provided with a reflux water outlet and a drainage outlet, wherein the drainage outlet is connected to the input end of the coagulation sedimentation tank 3, and the reflux water outlet is connected to the water inlet pipe through the reflux pump 202, and the water inlet pipe is connected to the expanded granular sludge bed 2 from the output end of the primary regulating tank 1, and the water inlet pipe is provided with a water inlet pump 201, which is used to pump the wastewater in the primary regulating tank 1 to the expanded granular sludge bed 2.

[0037] It can be understood that the hydrolysis and acidification reaction of the hydrothermal carbonized liquid in the expanded granular sludge bed 2 can convert the organic nitrogen in the hydrothermal carbonized liquid into ammonia nitrogen, thereby improving the conversion rate of organic nitrogen, and can convert the large molecular organic matter in the hydrothermal carbonized liquid into small molecular volatile fatty acids, thereby reducing the loss of organic matter, improving the yield, and at the same time improving the utilization rate of COD.

[0038] In some embodiments of the present invention, the deamination device further includes a second cell body 5, and the hollow fiber deamination membrane assembly 501 is disposed in the second cell body 5. It is understandable that the deamination device may only contain the hollow fiber deamination membrane assembly 501, that is, the hollow fiber deamination membrane assembly 501 is of an external design; or the deamination device is composed of the second cell body 5 and the hollow fiber deamination membrane assembly 501, that is, the hollow fiber deamination membrane assembly 501 is of a built-in design, and the hollow fiber deamination membrane assembly 501 can be backwashed in the second cell body 5, etc., and there is no special limitation on this, and it can be adjusted according to actual conditions.

[0039] The pore size of the hollow fiber deamination membrane component 501 is 0.1-1.0 μm, for example, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, etc. The material of the hollow fiber deamination membrane component 501 is polytetrafluoroethylene.

[0040] It is understandable that the setting of the hollow fiber deamination membrane assembly 501 can achieve efficient absorption of ammonia nitrogen in the hydrothermal carbonization liquid. The hollow fiber deamination membrane assembly 501 can be purchased on the market. Generally speaking, the smaller the pore size of the hollow fiber deamination membrane assembly 501, the higher the selectivity, and the better the separation effect of ammonia, but the permeability will deteriorate, the processing efficiency will decrease and the energy consumption will increase. The selection of the pore size of the hollow fiber deamination membrane assembly 501 can be determined according to actual conditions, and no special limitation is made on this.

[0041] In some embodiments of the present invention, the sludge hydrothermal carbonization liquid pretreatment device further includes an ammonium sulfate solution pool 7, and the deammoniation device is provided with an ammonium sulfate solution outlet, which is connected to the input end of the ammonium sulfate solution pool 7. In the hollow fiber deammoniation membrane module 501, the ammonia removed by the hollow fiber deammoniation membrane module 501 is absorbed by sulfuric acid to generate ammonium sulfate, and the generated ammonium sulfate is transported to the ammonium sulfate solution pool 7 for storage and reuse, for example, it can be reused as nitrogen fertilizer after crystallization.

[0042] In some embodiments of the present invention, sludge discharge ports are provided at the bottom of the primary regulating tank 1, the expanded granular sludge bed 2, and the coagulation sedimentation tank 3, and all the sludge discharge ports are connected to a sludge discharge pipe, and the discharged sludge can continue to be hydrothermally carbonized. Therefore, the carbon loss of the sludge hydrothermal carbonized liquid treated by the pretreatment device of the present invention is small, thereby realizing efficient recovery and reuse of the carbon source in the sludge hydrothermal carbonized liquid.

[0043] In another aspect of the present invention, the present invention also provides a sludge hydrothermal carbonization liquid pretreatment process, comprising the following steps:

[0044] (1) transporting the hydrothermal carbonized liquid to a primary regulating tank to adjust the pH value to obtain a primary adjusted carbonized liquid;

[0045] (2) transporting the initially adjusted carbonized liquid to an expanded granular sludge bed for hydrolysis and acidification to obtain a hydrolysis and acidification carbonized liquid;

[0046] (3) transporting the hydrolyzed acidified carbonized liquid to a coagulation sedimentation tank, adding a water treatment agent to perform phosphorus removal and flocculation sedimentation to obtain a phosphorus-removed carbonized liquid;

[0047] (4) transporting the dephosphorization carbonized liquid to a deammoniation device for deammoniation treatment to obtain a deammoniation carbonized liquid and an ammonium sulfate solution;

[0048] (5) Discharging the deammoniation carbonized liquid into a secondary regulating tank, adjusting the pH value to neutral, and obtaining a secondary carbonized liquid.

[0049] In some embodiments of the present invention, the hydrothermal carbonized liquid is transported to a primary regulating tank to adjust the pH value to obtain a pre-adjusted carbonized liquid.

[0050] Optionally, adjusting the pH value is to adjust the pH value to 4.5-5.5, for example, it can be 4.5, 5.0, 5.5, etc. It should be noted that the hydrothermal carbonization liquid is the filtrate after the sludge is carbonized with sulfuric acid and treated with a filter press, and the pH value is about 4, with some sludge remaining. By adding alkali to adjust the pH to 4.5-5.5, the pH value of the subsequent hydrolysis and acidification reaction in the expanded granular sludge bed can be guaranteed to be within a suitable range, and the solid residue remaining in the hydrothermal carbonization liquid can be initially precipitated. Among them, the pH value can be adjusted by adding waste alkali such as waste sodium hydroxide and waste sodium bicarbonate or conventional alkali solutions such as sodium hydroxide, sodium bicarbonate, calcium hydroxide, and sodium carbonate.

[0051] In some embodiments of the present invention, the initially adjusted carbonized liquid is transported to an expanded granular sludge bed for hydrolysis and acidification reaction to obtain a hydrolysis and acidification carbonized liquid.

[0052] It can be understood that the suitable pH value for the hydrolysis and 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 will produce alkaline substances and the pH value will increase by about 1 accordingly. Therefore, the initial pH value of the carbonization liquid is 4.5-5.5 to ensure the smooth progress of the hydrolysis and acidification reaction in the expanded granular sludge bed.

[0053] The present invention can convert organic nitrogen in the hydrothermal carbonized liquid into ammonia nitrogen by transporting the initially adjusted carbonized liquid to the expanded granular sludge bed for hydrolysis and acidification reaction, thereby improving the conversion rate of organic nitrogen, and can convert macromolecular organic matter in the hydrothermal carbonized liquid into small molecular volatile fatty acids, thereby improving the utilization rate of COD in the sludge hydrothermal carbonized liquid. Experimental studies have found that if the hydrothermal carbonized liquid is not treated by the expanded granular sludge bed, the COD in the hydrothermal carbonized liquid that can be used in the denitrification process of sewage treatment is less than 50%, while after being treated by the expanded granular sludge bed, the COD in the hydrothermal carbonized liquid that can be used for denitrification can be increased to about 70%, and after being treated by the expanded granular sludge bed, the utilization rate of the carbon source in the hydrothermal carbonized liquid can be effectively improved.

[0054] Optionally, the hydraulic retention time of the expanded granular sludge bed is 12-24 hours, for example, 12 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, etc. The longer the hydraulic retention time, the more the COD availability is improved, but it will also lead to a decrease in the COD content. Within the hydraulic retention time range specified by the invention, both the COD availability and the COD content can achieve good results.

[0055] Optionally, the temperature of the hydrolysis and acidification reaction is 25-45°C, for example, 25°C, 30°C, 35°C, 40°C, 45°C, etc. As the temperature increases, the reaction progresses faster, and the COD availability and organic nitrogen conversion rate increase accordingly. The reaction time is adjusted according to the reaction temperature. For example, when the reaction temperature is 45°C, it may take 12 hours, and when the reaction temperature is 30°C, it may take 16 hours. There is no special limitation on this, and it can be adjusted according to actual conditions.

[0056] 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 fully and accurately control the conditions in the expanded sludge particle bed, so the pH value is set to a range value, and a good treatment effect can be achieved within this pH value range.

[0057] Optionally, the internal reflow ratio of the expanded granular sludge bed is 10-50, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50, etc. The larger the internal reflow ratio, the better the mixing effect in the expanded granular sludge bed, and the better the treatment effect of the sludge hydrothermal carbonization liquid, but the larger the internal reflow ratio, the greater the power cost, so there is no special limitation on the internal reflow ratio, which can be selected according to actual needs.

[0058] In some embodiments of the present invention, the hydrolyzed acidified carbonized liquid is transported to a coagulation sedimentation tank, and water treatment agents are added to perform phosphorus removal and flocculation sedimentation to obtain a phosphorus-removed carbonized liquid.

[0059] Optionally, the water treatment agent is polyaluminium chloride and polyacrylamide, and the amount of polyaluminium chloride added is 10-20 times the mass content of phosphorus in the hydrolysis acidification carbonization liquid. Preferably, the effective concentration of polyaluminium chloride can be 30%. If the effective concentration of polyaluminium chloride decreases, the dosage increases accordingly. Optionally, based on the volume of the hydrolysis acidification carbonization liquid, the concentration of polyacrylamide added is 0.5-2mg / L, for example, 0.5mg / L, 1.0mg / L, 1.5mg / L, 2.0mg / L, etc. Among them, polyaluminium chloride acts on water to quickly form primary flocs, and polyacrylamide can further promote the aggregation and growth of these primary flocs to form more stable and easy-to-separate large flocs. The synergistic effect of the two improves the coagulation efficiency of the hydrothermal carbonization liquid, and also enhances the removal capacity of impurities such as suspended matter and colloids, and can more effectively remove phosphate ions to prevent them from polluting the water quality.

[0060] In some embodiments of the present invention, step (3) also includes the following process: transporting the dephosphorization carbonization liquid to a filtration device for filtration, and filtering small suspended particles in the wastewater through a hollow fiber ultrafiltration membrane component in the filtration device to prevent the deamination efficiency of the deamination device from being affected by the suspended matter.

[0061] In some embodiments of the present invention, the dephosphorization carbonized liquid is transported to a deammoniation device for deammoniation treatment to obtain a deammoniation carbonized liquid and an ammonium sulfate solution.

[0062] The principle of deamination through the hollow fiber deamination membrane assembly in the deamination device is to convert ammonium ions into free ammonia. Based on the principle of membrane contact reactor, the deamination membrane is used as the mass transfer interface, and the ammonium ions (NH 4 + ) is converted into free ammonia (NH 3 ), NH 3 The sulfuric acid solution outside the membrane is absorbed by the deammoniation membrane to form ammonium sulfate solution.

[0063] Optionally, during the deamination process, the dephosphorization carbonization liquid is adjusted to a pH of 9-13 before deamination 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, and thus more easily enter the absorption liquid through the micropores of the hollow fiber deamination membrane assembly to be absorbed, thereby improving the deamination effect.

[0064] Through deammoniation treatment, the ammonia nitrogen contained in the sludge hydrothermal carbonization liquid and the ammonia nitrogen converted from organic nitrogen can be completely removed, which can not only improve the C / N ratio of the sludge hydrothermal carbonization liquid, but also reduce the side effects of nitrogen on the sewage treatment plant.

[0065] In some embodiments of the present invention, the deammoniation carbonized liquid is discharged into a secondary regulating tank, and the pH value is adjusted to neutral to obtain a secondary carbonized liquid.

[0066] Optionally, after the hydrothermal carbonized liquid in the secondary regulating tank is adjusted to a pH of about 7 by adding an acidic solution, it can be added to the anaerobic section or anoxic section of the sewage treatment plant to supplement the carbon source.

[0067] In some embodiments of the present invention, the ammonium sulfate solution generated in step (4) is transported to an ammonium sulfate solution pool 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 sludge hydrothermal carbonization liquid.

[0068] The technical solutions in the present invention will be described clearly and completely below in conjunction with specific embodiments. The embodiments of the present application are only used as examples, and all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0069] The sludge hydrothermal carbonization liquid pretreatment device used in the following embodiments is as follows Figure 1 As shown, it includes a primary regulating tank 1, an expanded granular sludge bed 2, a coagulation sedimentation tank 3, a filtering device, a deammonification device and a secondary regulating tank 6 which are connected in sequence.

[0070] Among them, the primary regulating tank 1 is provided with a water inlet, which is connected to the hydrothermal carbonization liquid; a three-phase separator 203 is provided inside the expanded granular sludge bed 2, and the exhaust port of the three-phase separator 203 is connected to the gas collection device, and the expanded granular sludge bed 2 is provided with a reflux water outlet and a drainage outlet, and the drainage outlet is connected to the input end of the coagulation sedimentation tank 3, and the reflux water outlet is connected to the water inlet pipe through the reflux pump 202, and the water inlet pipe is connected to the expanded granular sludge bed 2 from the output end of the primary regulating tank 1, and a water inlet pump 201 is provided on the water inlet pipe; filtration The device includes a first tank body 4 and a hollow fiber ultra-microfiltration membrane assembly 401. The filtration device is connected to the output end of the coagulation sedimentation tank 3, and the hollow fiber ultra-microfiltration membrane assembly 401 is connected to the input end of the deamination device through a first outlet pump 402. The deamination device includes a second tank body 5 and a hollow fiber deamination membrane assembly 501. The input end of the secondary regulating tank 6 is connected to the liquid outlet of the hollow fiber deamination membrane assembly 501 through a second outlet pump 502. The deamination device is provided with an ammonium sulfate solution outlet, and the ammonium sulfate solution outlet is connected to the ammonium sulfate solution tank 7.

[0071] Example 1

[0072] This embodiment provides a sludge hydrothermal carbonization liquid pretreatment process, and the specific steps are as follows:

[0073] (1) The hydrothermal carbonized liquid of the excess sludge from the municipal sewage treatment plant is pumped into a primary regulating tank and then waste alkali is added to adjust the pH to 5.5 to obtain a primary carbonized liquid;

[0074] (2) pumping the initially adjusted carbonized liquid into the expanded granular sludge bed through a water inlet pump for hydrolysis and acidification reaction to obtain a hydrolysis and acidification carbonized liquid, the expanded granular sludge bed hydraulic retention time is 12 hours, the temperature is 25° C., the pH is 6.5, and the internal reflux ratio is 10;

[0075] (3) The hydrolysis acidified carbonized liquid is transported to a coagulation sedimentation tank, and 900 mg / L (about 10 times the phosphorus content in the hydrolysis acidified carbonized liquid) of polyaluminium chloride and 0.5 mg / L of polyacrylamide are added to remove phosphorus and sludge flocculation and sedimentation to obtain a dephosphorized carbonized liquid;

[0076] (4) The dephosphorization carbonization liquid is transported to the filtration device, and after filtering the small suspended particles through the 10 μm PVDF hollow fiber ultra-microfiltration membrane module, it enters the deammoniation device through the outlet pump;

[0077] (5) adding alkali to the wastewater of the deamination device to adjust the pH to 9, and then passing it through a 1.0 μm PTFF deamination device for deamination treatment, and then adding sulfuric acid to absorb the ammonia removed by the deamination device to obtain a deamination carbonized liquid and an ammonium sulfate solution, and the ammonium sulfate solution is transported to an ammonium sulfate solution pool for storage;

[0078] (6) The deammoniation carbonized liquid is discharged to the secondary regulating tank through the effluent pump, and the pH is adjusted to 6.8 by adding acid to obtain the secondary carbonized liquid, which is then added to the anaerobic section of the sewage treatment plant to supplement the carbon source.

[0079] The concentrations of COD, ammonia nitrogen, organic nitrogen and total phosphorus before and after the hydrothermal carbonization liquid pretreatment of the excess sludge from the municipal sewage treatment plant in this embodiment were measured, and the results are shown in Table 1.

[0080] Table 1

[0081] 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

[0082] Example 2

[0083] This embodiment provides a sludge hydrothermal carbonization liquid pretreatment process, and the specific steps are as follows:

[0084] (1) The hydrothermal carbonized liquid of the excess sludge from the brewery wastewater treatment plant is pumped into a primary regulating tank and then waste alkali is added to adjust the pH to 4.5 to obtain a primary carbonized liquid;

[0085] (2) pumping the initially adjusted carbonized liquid into the expanded granular sludge bed through a water inlet pump for hydrolysis and acidification reaction to obtain a hydrolysis and acidification carbonized liquid, the expanded granular sludge bed hydraulic retention time is 16 hours, the temperature is 30°C, the pH is 5.5, and the internal reflux ratio is 20;

[0086] (3) The hydrolysis acidified carbonized liquid is transported to a coagulation sedimentation tank, and 2800 mg / L (about 20 times of the hydrolysis acidified carbonized liquid) of polyaluminium chloride and 1 mg / L of polyacrylamide are added to remove phosphorus and sludge flocculation and sedimentation to obtain a dephosphorized carbonized liquid;

[0087] (4) The wastewater after coagulation and sedimentation is transported to the filtration device, and after filtering small suspended particles through a 1 μm PVDF hollow fiber ultra-microfiltration membrane module, it enters the deammoniation device through the outlet pump;

[0088] (5) adding alkali to the wastewater of the deamination device to adjust the pH to 9, and then passing it through a 0.5 μm PTFF deamination device for deamination treatment, and then adding sulfuric acid to absorb the ammonia removed by the deamination device to obtain a deamination carbonized liquid and an ammonium sulfate solution, and the ammonium sulfate solution is transported to an ammonium sulfate solution pool for storage;

[0089] (6) The deammoniation carbonized liquid is discharged to the secondary regulating tank through the effluent pump, and the pH is adjusted to 7.0 by adding acid to obtain the secondary carbonized liquid, which is then added to the anoxic section of the sewage treatment plant to supplement the carbon source.

[0090] The concentrations of COD, ammonia nitrogen, organic nitrogen and total phosphorus of the residual sludge hydrothermal carbonization liquid of the brewing wastewater treatment plant in this embodiment were measured before and after pretreatment, and the results are shown in Table 2.

[0091] Table 2

[0092] 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

[0093] Example 3

[0094] This embodiment provides a sludge hydrothermal carbonization liquid pretreatment process, and the specific steps are as follows:

[0095] (1) The hydrothermal carbonized liquid of the excess sludge from the pharmaceutical wastewater treatment plant is pumped into a primary regulating tank and then waste alkali is added to adjust the pH to 5 to obtain a primary carbonized liquid;

[0096] (2) pumping the initially adjusted carbonized liquid into the expanded granular sludge bed through a water inlet pump for hydrolysis and acidification reaction to obtain a hydrolysis and acidification carbonized liquid, wherein the hydraulic retention time of the expanded granular sludge bed is 24 h, the temperature is 45° C., the pH is 6, and the internal reflux ratio is 50;

[0097] (3) The hydrolysis acidified carbonized liquid is transported to a coagulation sedimentation tank, and 4200 mg / L (about 15 times the hydrolysis acidified carbonized liquid) of polyaluminium chloride and 2 mg / L of polyacrylamide are added to remove phosphorus and sludge flocculation and sedimentation to obtain a dephosphorized carbonized liquid;

[0098] (4) The wastewater in the coagulation and sedimentation is transported to the filtration device, and after filtering the small suspended particles through the 0.01 μm PTFF hollow fiber ultra-microfiltration membrane module, it enters the deammoniation device through the outlet pump;

[0099] (5) adding alkali to the wastewater of the deamination device to adjust the pH to 9, and then passing it through a two-stage 0.1 μm PTFF deamination device for deamination treatment, and then adding sulfuric acid to absorb the ammonia removed by the deamination device to obtain a deamination carbonized liquid and an ammonium sulfate solution, and the ammonium sulfate solution is transported to an ammonium sulfate solution pool for storage;

[0100] (6) The deammoniation carbonized liquid is discharged to the secondary regulating tank through the effluent pump, and the pH is adjusted to 7.2 by adding acid to obtain the secondary carbonized liquid. The secondary carbonized liquid is added to the anaerobic section of the sewage treatment plant to supplement the carbon source.

[0101] The concentrations of COD, ammonia nitrogen, organic nitrogen and total phosphorus before and after the hydrothermal carbonization liquid pretreatment of the excess sludge from the pharmaceutical wastewater treatment plant in this embodiment were measured, and the results are shown in Table 3.

[0102] Table 3

[0103] 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

[0104] In Examples 1-3, Example 1 is directed to the hydrothermal carbonized liquid of excess sludge from a municipal sewage treatment plant, and the concentration values ​​of various pollutants are relatively low. Example 2 is directed to the hydrothermal carbonized liquid of excess sludge from a brewery sewage treatment plant, and the nitrogen and phosphorus concentrations are medium, the total COD concentration is high, but the proportion of difficult-to-degrade COD is relatively low. Example 3 is directed to the hydrothermal carbonized liquid of excess sludge from a pharmaceutical sewage treatment plant, and the total nitrogen, phosphorus and COD concentrations are high, and the proportion of difficult-to-degrade COD is also high. Based on the concentration values ​​of various pollutants in different sludge hydrothermal carbonized liquids, Examples 1-3 use lower values, medium values ​​and higher values ​​for the parameters of the expanded granular sludge bed, the amount of water treatment agent added, the pore size of the membrane, etc., respectively, and because the values ​​of the parameters in each process step are different, the treatment effects on nitrogen, phosphorus and COD are also different.

[0105] In summary, the sludge hydrothermal carbonized liquid pretreatment device and process of the present invention can effectively reduce the nitrogen and phosphorus in the sludge hydrothermal carbonized liquid, not only can effectively reduce the concentration of ammonia nitrogen, but also can effectively reduce the concentration of organic nitrogen, reduce the impact of the biochemical section of the sewage treatment plant, and ensure the stability and efficiency of sewage treatment.

[0106] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A sludge hydrothermal carbonization liquid pretreatment device, characterized in that: It includes a primary regulating tank, an expanded granular sludge bed, a coagulation sedimentation tank, a deammonification device and a secondary regulating tank which are connected in sequence; The primary regulating tank is provided with a water inlet, which is communicated with the hydrothermal carbonized liquid. The deamination device comprises a hollow fiber deamination membrane assembly, which is provided with a deamination carbonized liquid discharge outlet. The input end of the secondary regulating tank is communicated with the deamination carbonized liquid discharge outlet.

2. The sludge hydrothermal carbonization liquid pretreatment device according to claim 1 is characterized in that: It also includes a filtering device, which is connected to the output end of the coagulation sedimentation tank; The filtering device comprises a hollow fiber ultra-microfiltration membrane assembly, and the hollow fiber ultra-microfiltration membrane assembly is connected to the input end of the deamination device.

3. The sludge hydrothermal carbonization liquid pretreatment device according to claim 1 is characterized in that: The expanded granular sludge bed is provided with a return water outlet and a drainage outlet; The return water outlet is connected to the water inlet pipe through a return pump, and the water inlet pipe is connected to the expanded granular sludge bed from the output end of the primary regulating tank; The drainage outlet is communicated with the input end of the coagulation sedimentation tank.

4. The sludge hydrothermal carbonization liquid pretreatment device according to claim 2 is characterized in that: 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; 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.

5. The sludge hydrothermal carbonization liquid pretreatment device according to any one of claims 1 to 4, characterized in that: It also includes an ammonium sulfate solution pool, and the deammoniation device is provided with an ammonium sulfate solution outlet, and the ammonium sulfate solution outlet is connected to the input end of the ammonium sulfate solution pool.

6. The sludge hydrothermal carbonization liquid pretreatment device according to any one of claims 1 to 4, characterized in that: The bottoms of the primary regulating tank, the expanded granular sludge bed and the coagulation sedimentation tank are all provided with sludge discharge ports.

7. A sludge hydrothermal carbonization liquid pretreatment process using the device according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) transporting the hydrothermal carbonized liquid to a primary regulating tank to adjust the pH value to obtain a primary adjusted carbonized liquid; (2) transporting the initially adjusted carbonized liquid to an expanded granular sludge bed for hydrolysis and acidification to obtain a hydrolysis and acidification carbonized liquid; (3) transporting the hydrolyzed acidified carbonized liquid to a coagulation sedimentation tank, adding a water treatment agent to perform phosphorus removal and flocculation sedimentation to obtain a phosphorus-removed carbonized liquid; (4) transporting the dephosphorization carbonized liquid to a deammoniation device for deammoniation treatment to obtain a deammoniation carbonized liquid and an ammonium sulfate solution; (5) Discharging the deammoniation carbonized liquid into a secondary regulating tank, adjusting the pH value to neutral, and obtaining a secondary carbonized liquid.

8. The sludge hydrothermal carbonization liquid pretreatment process according to claim 7, characterized in that: Step (3) also The method comprises the following steps: transporting the dephosphorization carbonization liquid to a filtering device to remove suspended matter.

9. The sludge hydrothermal carbonization liquid pretreatment process according to claim 7, characterized in that: The hydraulic retention time of the expanded granular sludge bed in step (2) is 12-24 hours, the temperature is 25-45° C., the pH value is 5.5-6.5, and the internal reflux ratio is 10-50; In step (3), the water treatment reagents are polyaluminium chloride and polyacrylamide, the amount of polyaluminium chloride added is 10-20 times the mass content of phosphorus in the hydrolysis acidification carbonization liquid, and the concentration of polyacrylamide added is 0.5-2 mg / L.

10. The sludge hydrothermal carbonization liquid pretreatment process according to any one of claims 7 to 9, characterized in that: The following steps are also included: The ammonium sulfate solution is transported to an ammonium sulfate solution pool for crystallization to obtain ammonium sulfate.

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