Sludge modification anaerobic coupling reduction method and system

Abstract

The invention provides a sludge modification anaerobic coupling reduction method and system. The method comprises the following steps: (1) adding a high-efficiency lysate and alkali into dewatered residual sludge, and carrying out pyrohydrolysis and flash evaporation treatment to obtain sludge hydrolysate; and (2) mixing the sludge hydrolysate obtained in the step (1) with industrial sewage, carrying out anaerobic reaction in an anaerobic reaction device, then carrying out three-phase separation, and separating water and gas to obtain reduced sludge. The method disclosed by the invention is high in treatment efficiency, stable in operation and relatively low in operation and maintenance cost, realizes reduction and recycling of the sludge under the condition of relatively low operation energy consumption of the device, is good in reduction effect, can generate biogas in the sludge reduction process, and can be further recycled.

Description

Technical Field

[0001] The invention relates to the technical field of sewage sludge treatment, and more particularly to a method and system for sludge modification and anaerobic coupling reduction. Background Art

[0002] The sewage treatment equipment of enterprises will produce a large amount of biochemical sludge during operation. At present, the main treatment solutions for biochemical sludge are concentration, centrifugal dehydration or further drying. However, after concentration and dehydration, the water content of biochemical sludge is still about 85%, the sludge reduction is limited, and the incineration of sludge with high water content mixed with coal powder also has the disadvantages of low calorific value. If the drying process is used to further reduce the water content of sludge, it will face high equipment construction investment costs and operation and maintenance costs.

[0003] The prior art also has a method of directly subjecting the dewatered sludge to anaerobic reaction after thermal hydrolysis. However, this method not only requires the establishment of an anaerobic reaction device specifically for the sludge hydrolyzate, which has a high investment cost, but also the viscosity of the dewatered sludge after thermal hydrolysis is still very high and the fluidity is poor, which can easily cause blockage of the anaerobic equipment and pipelines, and is not conducive to the continuous anaerobic reaction.

[0004] Therefore, it is necessary to study a set of solutions for the reduction and resource utilization of biochemical sludge produced by enterprise sewage treatment devices, which can not only achieve effective sludge reduction, but also have low operating and maintenance costs, and achieve sludge reduction and resource utilization under low energy consumption of device operation. Summary of the invention

[0005] In order to solve the technical problems existing in the prior art, the present invention provides a method and system for sludge modification and anaerobic coupled reduction.

[0006] The present invention firstly performs efficient cell lysis and thermal hydrolysis treatment on the dehydrated biochemical sludge to greatly improve its biodegradability, then mixes and dilutes it with biodegradable sewage in a certain proportion, and then enters the anaerobic reaction device for digestion and reduction, and generates biogas, thereby achieving sludge reduction and resource utilization. The anaerobic reaction device can directly use the anaerobic reaction device of sewage treatment, and there is no need to re-establish a production device for anaerobic treatment of sludge, which has better economy and has no adverse effect on further biochemical treatment of downstream sewage.

[0007] The present invention treats the dehydrated sludge after thermal hydrolysis by adopting the anaerobic treatment process of sewage, with high treatment efficiency, stable operation, low energy consumption of device operation, and realizes the reduction and resource utilization of sludge, providing a set of reduction and resource disposal solutions for the biochemical sludge generated by the enterprise sewage treatment device.

[0008] One of the purposes of the present invention is to provide a method for sludge modification and anaerobic coupled reduction, comprising the following steps:

[0009] (1) adding a high-efficiency lysing agent and alkali to the residual sludge after dehydration, performing thermal hydrolysis and flash evaporation treatment to obtain a sludge hydrolyzate;

[0010] (2) The sludge hydrolyzate obtained in step (1) is mixed with industrial sewage, and then subjected to anaerobic reaction in an anaerobic reaction device, followed by three-phase separation to separate water and gas, thereby obtaining reduced sludge.

[0011] Step (1) is carried out in the sludge thermal hydrolysis reaction section. The high-temperature thermal hydrolysis of sludge is an efficient sludge pretreatment technology. It takes high-solid dehydrated sludge (solid content 10-20%) as the object, and adopts high temperature (150-180°C) and high pressure (6-8bar) to perform thermal hydrolysis and flash evaporation on the sludge. The dehydrated sludge is subjected to high temperature, high pressure and pressure release instantly, forcing the molecular structure of the sludge to change, causing the extracellular polymers and macromolecular organic matter in the sludge to hydrolyze, and breaking the cell wall of the microorganisms in the sludge, strengthening the biodegradable properties of the material, and improving the fluidity of the material. At the same time, by adding an efficient sludge lysing agent, the viscosity of the sludge can be greatly reduced, and the organic matter conversion rate and cell fragmentation rate can be improved.

[0012] Step (2) is carried out in the anaerobic reaction section. The main process of the anaerobic reaction device consists of a circulating feed tank and an anaerobic reactor. The sludge hydrolyzate produced by the sludge thermal hydrolysis reaction section is mixed and homogenized with the mixed sewage in the regulating tank, and then pumped to the anaerobic reaction device. A certain amount of acid and alkali agents are added to adjust the pH value of the sewage. According to the water quality of the mixed sewage (such as the content of nitrogen and phosphorus elements, etc.), an appropriate amount of nutrient salts is added to meet the growth requirements of the granular sludge in the anaerobic reactor. After the efficient anaerobic reaction of the granular sludge in the anaerobic reaction device, most of the organic matter in the sewage is converted into CH4 and CO2.

[0013] In a preferred embodiment of the present invention,

[0014] Step (1),

[0015] The moisture content of the residual sludge after dehydration is 80-90%, preferably 83-86%;

[0016] The high-efficiency lytic agent can be a lytic agent commonly used in the art, which is a preparation that can accelerate cell wall breaking. Its function is to break the cell walls of microorganisms in the sludge, enhance the biodegradable properties of the material, and improve the fluidity of the material; the high-efficiency lytic agent of the present invention is preferably a high-efficiency lytic agent of Shanghai Li Ze Environmental Protection Technology Co., Ltd., whose main components include α-amylase, phytase and lipase (the publication number of the high-efficiency lytic agent is CN108623120B, and the name of the invention is "A composition, its preparation method and use"). By adding the high-efficiency lytic agent, the SCOD concentration of the sludge hydrolyzate can be increased by 1.5 times.

[0017] The temperature of the thermal hydrolysis is 150-180°C;

[0018] The pressure of the thermal hydrolysis is 6 to 8 bar;

[0019] The thermal hydrolysis time is 30 to 60 minutes;

[0020] The flash evaporation temperature is 110-130°C;

[0021] The flash evaporation pressure is 1 to 3 bar.

[0022] In a preferred embodiment of the present invention,

[0023] Step (1),

[0024] The mass ratio of the high-efficiency lysing agent to the excess sludge after dehydration is (0.001-0.003):1, preferably (0.0015-0.0025):1;

[0025] The alkali is a sodium hydroxide aqueous solution, preferably a 20-40% sodium hydroxide aqueous solution, more preferably a 30% sodium hydroxide aqueous solution, and further preferably, the mass ratio of the sodium hydroxide aqueous solution to the dehydrated excess sludge is (0.001-0.003):1, preferably (0.0015-0.0025):1.

[0026] In a preferred embodiment of the present invention,

[0027] The sludge hydrolyzate obtained in step (1) has a pH of 6 to 9, a viscosity of <100 cp, a moisture content of 90 to 92%, a SCOD of ≥30,000 mg / L, preferably 30,000 to 36,000 mg / L, a BOD / COD of ≥0.4, and a density of 1,150 to 1,300 kg / m 3 .

[0028] The sludge hydrolyzate has low viscosity, is easy to transport through pipelines, and is not prone to clogging equipment and pipelines.

[0029] The SCOD of the sludge after thermal hydrolysis is greater than 30,000 mg / L, and the BOD / COD is ≥ 0.4, indicating that the organic matter conversion rate and cell fragmentation rate are greatly improved, and anaerobic decomposition can be more thorough.

[0030] In a preferred embodiment of the present invention,

[0031] Step (2),

[0032] The sludge hydrolyzate obtained in step (1) is first mixed with industrial sewage and then introduced into an anaerobic reaction device to adjust the pH value. Optionally, nutrient salts are added to carry out anaerobic reaction.

[0033] Nutrient salts are added according to the water quality of industrial sewage. The main function is to ensure that the mass ratio of COD equivalent to nitrogen and phosphorus in the mixed sewage after the sludge hydrolyzate and industrial sewage are (200-300): (4-6): 1. If it is within this ratio, no nutrient salts may be added.

[0034] In a preferred embodiment of the present invention,

[0035] The industrial sewage is sewage with good biodegradability and suitable for the water inlet requirements of anaerobic reaction devices. Sewage with good biodegradability usually means that the pollutant components in the sewage are non-biotoxic and can be decomposed and utilized by microorganisms; the COD range of industrial sewage is usually 2000-8000 mg / L, more preferably 5000-8000 mg / L; the BOD / COD of industrial sewage should be greater than 0.3 to ensure the biodegradability of industrial sewage; the suspended solids content in industrial sewage should be less than 1500 mg / L, the ammonia nitrogen content should be less than 2000 mg / L, the sulfide content should be less than 65 mg / L, and it does not contain biotoxic substances, such as heavy metals such as mercury and chromium.

[0036] The mass ratio of industrial sewage to sludge hydrolyzate is greater than or equal to 100; further preferably, the COD of the mixed sewage of sludge hydrolyzate and industrial sewage entering the anaerobic reaction device is ≤10000 mg / L, preferably 2000-10000 mg / L;

[0037] Adjust the pH value with an acid or a base; the acid is preferably one of hydrochloric acid and phosphoric acid; the base is preferably one of sodium hydroxide and calcium hydroxide;

[0038] The pH value is 6 to 9, preferably 7 to 8;

[0039] The nutrient salt refers to an agent for supplementing conventional nutrients such as nitrogen and phosphorus, preferably at least one of urea and phosphate;

[0040] In a preferred embodiment of the present invention,

[0041] Before entering the anaerobic reaction device, the mass ratio of COD equivalent of carbon to nitrogen and phosphorus in the mixed sewage after the sludge hydrolyzate is mixed with industrial sewage is (200-300): (4-6): 1 (wherein carbon is expressed as COD, and nitrogen and phosphorus are expressed as element content); based on the water quality analysis of the mixed sewage, the nutrient salts that need to be added are determined, and then adjusted according to the actual operating conditions during operation.

[0042] The addition of nutrient salts is related to the COD content and the nitrogen and phosphorus content in the water quality of the anaerobic reactor inlet. It is necessary to ensure that the mass ratio of carbon (COD): nitrogen: phosphorus is (200-300): (4-6): 1 (where carbon is expressed as COD, and nitrogen and phosphorus are expressed as elemental content). For example: if the added nutrient salt is urea, then in order to ensure the above carbon, nitrogen and phosphorus ratio, the mass ratio of sewage COD to urea is (200-300): (8-13).

[0043] In a preferred embodiment of the present invention,

[0044] Step (2),

[0045] The anaerobic reaction device comprises a circulating feed tank and an anaerobic reactor; the pH value is adjusted and nutrient salts are added in the circulating feed tank; and the anaerobic reaction is carried out in the anaerobic reactor.

[0046] The anaerobic reaction device for utilizing sludge hydrolyzate and industrial sewage is an existing sewage anaerobic reaction device. Using the sewage anaerobic reaction device to treat dewatered sludge is a first in this field. The existing sewage anaerobic reaction device can be effectively utilized without the need for additional construction, and the economic benefits are better.

[0047] In a preferred embodiment of the present invention,

[0048] The type of the anaerobic reactor can be the anaerobic reactor used in the existing sewage treatment process of the enterprise, such as an anaerobic internal circulation (IC) reactor, an anaerobic collision granular sludge blanket (EGSB) reactor, an upflow anaerobic sludge blanket (UASB) reactor and other types of anaerobic reactors. Preferably, the anaerobic reactor is provided with upper and lower layers of three-phase separators, the effluent of the lower three-phase separator is provided with an internal reflux device, the effluent of the upper three-phase separator is provided with an external reflux device, and the outer shell of the anaerobic reactor is insulated.

[0049] After the anaerobic reaction, the sludge, methane gas and treated water are separated through the upper and lower three-phase separators installed in the reactor; the effluent from the anaerobic reactor is distributed through a riser; part of the water flows back to the circulating feed tank, and the other part of the water flows to the downstream sewage treatment system by gravity; a biogas degassing tank is installed on the top of the anaerobic reactor, and the biogas is separated from the degassing and aerating liquid and then sent out for comprehensive utilization.

[0050] In a preferred embodiment of the present invention,

[0051] The temperature of the anaerobic reaction is 30-40°C, preferably 33-35°C;

[0052] The pressure of the anaerobic reaction is normal pressure;

[0053] The organic volume load of the anaerobic reaction is 3-30 kgCODcr / (m 3.d) The selection should be made based on the type of anaerobic reactor used and the biodegradability of the mixed sewage;

[0054] The anaerobic reaction time is 10 to 16 hours;

[0055] The COD removal rate of the anaerobic reaction is 80-90%;

[0056] The moisture content of the granular sludge produced by the anaerobic reaction is 90-92%;

[0057] The sludge yield of the anaerobic reaction is 0.05-0.10 kg VSS / kg COD;

[0058] The biogas yield of the anaerobic reaction is 0.3-0.4 Nm 3 / kgCOD.

[0059] After the dewatered sludge is treated with thermal hydrolysis, it becomes thermal hydrolysis liquid, which is mixed with industrial sewage and treated in an anaerobic reactor. The COD of the mixed sewage will produce a small amount of granular sludge during the digestion process, which is the sludge yield of the anaerobic reaction. The sludge yield of the anaerobic reaction described in this patent is 0.05-0.10 kgVSS / kg COD (based on the values ​​of HJ 2023-2012 and HJ 2013-2012).

[0060] The calculation formula of sludge reduction rate is as follows:

[0061]

[0062] W—sludge reduction rate %;

[0063] C—SCOD concentration of thermal hydrolysis liquid kg / m 3 ;

[0064] K—COD removal rate (%);

[0065] P—density of thermal hydrolysis liquid kg / m 3 ;

[0066] A—water content of thermal hydrolysis solution (%);

[0067] B—moisture content of dewatered sludge %;

[0068] D—granular sludge moisture content%;

[0069] S—anaerobic reaction sludge yield kgVSS / kg COD.

[0070] The amount of biogas generated during sludge reduction can be calculated using the following formula:

[0071] Q1=Q2×C×K×V

[0072] Q1—biogas volume Nm 3 / h;

[0073] Q2—sludge hydrolyzate volume m 3 / h;

[0074] C—SCOD concentration of sludge hydrolyzate kg / m 3 ;

[0075] K—COD removal rate of anaerobic reactor %;

[0076] V—Gas production rate of anaerobic reactor Nm 3 / kgCOD.

[0077] The second object of the present invention is to provide a sludge modification anaerobic coupled reduction system, comprising a thermal hydrolysis reaction section and an anaerobic reaction section; the thermal hydrolysis reaction section comprises a sludge storage tank, a high-efficiency lysing agent dosing device, an alkali dosing device, a sludge heat exchanger, a sludge heater, a homogenization kettle, a homogenization liquid heater, a reactor, a flash kettle and a sludge hydrolyzate heat exchanger; the anaerobic reaction section comprises a regulating tank, a circulating feed tank and an anaerobic reactor;

[0078] The sludge storage tank is connected to the sludge heat exchanger through a pump, the high-efficiency lysing agent dosing device and the alkali dosing device are respectively connected to the pipeline between the sludge storage tank and the sludge heat exchanger, the sludge heat exchanger, the homogenizer kettle, and the homogenizer liquid heater are connected in sequence, the homogenizer liquid heater is connected to the reactor, the reactor is connected to the flash kettle, the steam pipeline of the flash kettle is connected to the sludge storage tank, the liquid pipeline is connected to the sludge heat exchanger, the sludge heat exchanger is connected to the sludge hydrolyzate heat exchanger, the sludge hydrolyzate heat exchanger is connected to the regulating tank, the regulating tank is connected to the circulating feed tank, the circulating feed tank is provided with an acid and alkali liquid inlet and a nutrient salt (urea, phosphate, etc.) dosing port, the nutrient salt dosing port is connected to the nutrient salt dosing device, the circulating feed tank is connected to the anaerobic reactor, the anaerobic reactor is provided with a biogas outlet and a water outlet, the biogas outlet is connected to the biogas degassing tank, wherein the water outlet is divided into two pipelines, one is connected to the circulating feed tank to form an external circulation, and the other is connected to the downstream biochemical treatment system.

[0079] Compared with the prior art, the present invention has the following beneficial effects:

[0080] The invention is different from the prior art in which the biochemical sludge is concentrated and centrifugally dehydrated, or the biochemical sludge is dehydrated and then subjected to thermal hydrolysis for direct anaerobic reaction and other subsequent treatments: the invention first dehydrates the biochemical sludge in the thermal hydrolysis reaction section, and then thermally hydrolyzes it in the presence of a high-efficiency lysing agent, which can accelerate the cell wall breaking of microorganisms in the dehydrated sludge and greatly improve its biodegradability, and then flash evaporation is performed to obtain a sludge hydrolyzate with low viscosity, good fluidity and good biochemical performance; the invention mixes the obtained sludge hydrolyzate with industrial sewage in the anaerobic reaction section, and uses an anaerobic reaction device for sewage to treat the dehydrated sludge, which is a first in the art. On the one hand, the existing anaerobic reaction device for sewage can be effectively used, and there is no need to build an anaerobic reaction device dedicated to sludge or an expensive sludge drying device, so the economic benefits of production are better; on the other hand, a large amount of industrial sewage is consumed while treating the dehydrated sludge, which is equivalent to treating sewage at the same time, and energy consumption is more economical, which also improves the economic benefits of production.

[0081] The system of the present invention has high treatment efficiency and stable operation. By adopting anaerobic treatment technology, the energy consumption of device operation is reduced, and the operation and maintenance costs are low. The sludge reduction and resource utilization are achieved under the condition of low device operation energy consumption, and a set of reduction and resource utilization disposal solutions are provided for the biochemical sludge generated by the enterprise sewage treatment device.

[0082] Compared with the prior art, the present invention has a better effect on reducing the amount of dewatered sludge, which can reach a 95% reduction. After the dewatered sludge with a moisture content of about 85% is pretreated by thermal hydrolysis and treated by an anaerobic reactor, most of the COD in the dewatered sludge is digested and turned into water, carbon dioxide and methane, and a small part of the COD enters the downstream biochemical treatment unit together with the effluent of the anaerobic reactor; the insoluble particles in the dewatered sludge enter the granular sludge at the bottom of the anaerobic reactor, which can be used as bacteria, retained or sold as a commodity. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 This is a schematic diagram of the sludge thermal hydrolysis process;

[0084] Figure 2 Schematic diagram of the anaerobic reaction process. DETAILED DESCRIPTION

[0085] The present invention is described in detail below in conjunction with specific drawings and embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0086] Figure 1It is a schematic diagram of the process of the sludge thermal hydrolysis reaction section; it includes a sludge storage tank, a high-efficiency lysing agent dosing device, an alkali dosing device, a sludge heat exchanger, a sludge heater, a homogenizer kettle, a homogenate liquid heater, a reactor, a flash kettle and a sludge hydrolyzed liquid heat exchanger; the sludge storage tank is connected to the sludge heat exchanger through a pump, the high-efficiency lysing agent dosing device and the alkali dosing device are respectively connected to the static mixer provided on the pump outlet pipeline between the sludge storage tank and the sludge heat exchanger, the sludge heat exchanger, the sludge heater, the homogenizer kettle and the homogenate liquid heater are connected in sequence, the homogenate liquid heater is connected to the reactor, the reactor is connected to the flash kettle, the steam pipe of the flash kettle is connected to the sludge storage tank, the liquid pipe is connected to the sludge heat exchanger, and the sludge heat exchanger is connected to the sludge hydrolyzed liquid heat exchanger. During production, the dewatered sludge enters the sludge storage tank for temporary storage and is lifted to the sludge heat exchanger by a pump for preheating; a static mixer is provided on the pump outlet pipeline, and a high-efficiency lysing agent is added to the static mixer through a high-efficiency lysing agent dosing device to mix with the dewatered sludge, and alkali is added to the static mixer through an alkali dosing device to mix with the dewatered sludge; the heat exchange medium of the sludge heat exchanger is the sludge hydrolyzate produced by the flash kettle, and the sludge preheated by the sludge heat exchanger (temperature is about 40-60°C) enters the sludge heater for heating until its temperature is raised to 90-100°C, and then enters the homogenization kettle for slurrying for 20-40 minutes. The material discharged from the homogenizer (material temperature 90-100°C) is lifted by the homogenizer liquid delivery pump to the homogenizer liquid heater for reheating until the sludge temperature is raised to 150-170°C, and then enters the reactor; after the material stays in the reactor for 20-40 minutes, it enters the flash kettle for flash evaporation, and the waste steam at the top of the flash kettle is discharged into the sludge storage tank. The material discharged from the bottom of the flash kettle is sludge hydrolyzate (temperature 100-120°C), which is then lifted to the sludge heat exchanger by a pump. After recovering part of the heat as a heat exchange material, it enters the sludge hydrolyzate heat exchanger, and enters the anaerobic reaction section after being cooled to 30-40°C.

[0087] Figure 2It is a schematic diagram of the anaerobic reaction process; it includes a regulating tank, a circulating feed tank and an anaerobic reactor; the sludge hydrolyzate heat exchanger is connected to the regulating tank, the regulating tank is connected to the circulating feed tank, the circulating feed tank is provided with an acid and alkali liquid inlet and a nutrient salt (urea, phosphate, etc.) addition inlet, the nutrient salt addition inlet is connected to the nutrient salt addition device, the circulating feed tank is connected to the anaerobic reactor, the anaerobic reactor is provided with a biogas outlet and a water outlet, the biogas outlet is connected to a biogas degassing tank, wherein the water outlet is divided into two pipelines, one is connected to the circulating feed tank to form an external circulation, and the other is connected to the downstream biochemical treatment system. The sludge hydrolyzate is cooled to 30-40°C and then enters a regulating tank. The industrial sewage is introduced into the regulating tank and mixed with the sludge hydrolyzate, and then pumped into a circulating feed tank. The pH value of the mixed solution is adjusted to 6-9 by adding acid and alkali solution. Nutrients (urea, phosphate, etc.) are added into the circulating feed tank through a dosing device through a nutrient salt dosing port, so that the mass ratio of the COD equivalent of carbon to nitrogen and phosphorus in the mixed sewage after the sludge hydrolyzate and the industrial sewage are (200-300): (4-6): 1; the sludge hydrolyzate is pumped into an anaerobic reactor for anaerobic reaction. The temperature of the anaerobic reaction is 30-40°C and the time is 10-16 hours. The product is separated into three phases to obtain biogas, water and dehydrated and reduced sludge. The biogas enters a biogas degassing tank for reuse, the water part can enter a circulating feed tank for reuse, and the part is discharged to a downstream biochemical treatment system.

[0088] The raw materials used in the examples are all commercially available products.

[0089] The high-efficiency lytic agent used in the embodiment is homemade and prepared with reference to patent CN108623120B (the invention name is "A composition, its preparation method and use"). Its main components include α-amylase, phytase and lipase. By adding the high-efficiency lytic agent, the SCOD concentration of the sludge hydrolyzate can be increased by 1.5 times.

[0090] The high-efficiency lytic agent was prepared according to Example 1 of patent CN108623120B.

[0091] Test method:

[0092] PH determination standard number GB / T 6920;

[0093] Viscosity determination standard number GB / T 10247;

[0094] Moisture content determination standard number CJ / T 221;

[0095] SCOD determination standard number GB / T 11914;

[0096] BOD determination standard number HJ505;

[0097] The COD removal amount of the anaerobic reactor is the COD value of the anaerobic reactor inlet minus the COD value of the effluent;

[0098] Anaerobic reactor COD removal rate: the ratio of anaerobic reactor COD removal to anaerobic reactor influent COD;

[0099] Anaerobic sludge yield: the ratio of the amount of sludge produced by the anaerobic reactor (regular sludge discharge) to the amount of COD removed by the anaerobic reactor;

[0100] Gas production rate of anaerobic reactor: the ratio of the amount of biogas produced by the anaerobic reactor to the amount of COD removed by the anaerobic reactor;

[0101] Granular sludge moisture content determination standard number CJ / T 221;

[0102] The amount of biogas produced during the sludge reduction process is measured by setting a flow meter at the exhaust port on the top of the anaerobic reactor.

[0103] Suspended matter determination standard number GB / T 11901;

[0104] Ammonia nitrogen determination standard number HJ 535;

[0105] Sulfide determination standard number GB / T 16489.

[0106] Example 1

[0107] A high-efficiency lysing agent and a 30% sodium hydroxide aqueous solution were added to the excess sludge after dehydration, wherein the moisture content of the excess sludge was 83%, the mass ratio of the high-efficiency lysing agent to the excess sludge was 0.0025:1, and the mass ratio of the 30% sodium hydroxide aqueous solution to the excess sludge was 0.0025:1. Hydrolysis was performed at a temperature of 180°C, a pressure of 8 bar, and a time of 30 minutes for thermal hydrolysis. Afterwards, flash evaporation was performed at a temperature of 130°C and a pressure of 3 bar. The density of the sludge hydrolyzate obtained after flash evaporation was 1200 kg / m 3 ; SCOD is 36000mg / L; water content is 91%, pH is 7, viscosity is 90cp, and BOD / COD value is 0.43.

[0108] The sludge hydrolyzate was mixed with industrial sewage at a mass ratio of 1:150, wherein the COD of the industrial sewage was 5000 mg / L, and the BOD / COD of the industrial sewage was 0.33. The pH value was adjusted to 7-8 with sodium hydroxide solution, and urea was added. After adding urea, the mass ratio of the COD equivalent of carbon to nitrogen and phosphorus in the mixed sewage was 250:5:1. The sludge hydrolyzate was introduced into the anaerobic reactor for anaerobic reaction. The temperature of the anaerobic reaction was 33-35°C, the pressure of the anaerobic reaction was normal pressure, the time of the anaerobic reaction was 16 hours, and the organic volume load of the anaerobic reaction was 30 kgCODcr / (m 3.d) The COD removal rate of the anaerobic reactor is 90%; the sludge yield of the anaerobic reaction is 0.08kgVSS / kgCOD; the gas production rate of the anaerobic reactor is 0.4Nm 3 / kgCOD; the moisture content of the granular sludge produced by anaerobic reaction is 91%. After three-phase separation, the biogas enters the biogas degassing tank for reuse, part of the water is discharged into the downstream biochemical treatment system, and part enters the circulating feed tank for reuse, achieving a sludge reduction of 95.5%. The amount of biogas generated during the sludge reduction process is 12.96Nm 3 .

[0109] Example 2

[0110] A high-efficiency lysing agent and a 25% sodium hydroxide aqueous solution were added to the excess sludge after dehydration, wherein the moisture content of the excess sludge was 86%, the mass ratio of the high-efficiency lysing agent to the excess sludge was 0.0015:1, and the mass ratio of the sodium hydroxide aqueous solution to the excess sludge was 0.0015:1. Hydrolysis was performed at a temperature of 150°C, a pressure of 6 bar, and a time of 60 minutes for thermal hydrolysis. Afterwards, flash evaporation was performed at a temperature of 110°C and a pressure of 1 bar. The density of the sludge hydrolyzate obtained after flash evaporation was 1150 kg / m 3 ; SCOD is 30000mg / L; water content: 90%, PH is 7.5, viscosity is 80cp, BOD / COD value is 0.4.

[0111] The sludge hydrolyzate is mixed with industrial sewage at a mass ratio of 1:100, wherein the COD of industrial sewage is 6000mg / L, and the BOD / COD of industrial sewage is 0.3. The pH value is adjusted to 7-8 with sodium hydroxide solution, and urea is added. After adding urea, the mass ratio of the COD equivalent of carbon to nitrogen and phosphorus in the mixed sewage is 200:4:1. It enters the anaerobic reactor for anaerobic reaction. The temperature of the anaerobic reaction is 33-35℃, the pressure of the anaerobic reaction is normal pressure, the time of the anaerobic reaction is 10h, and the organic volume load of the anaerobic reaction is 3kgCODcr / (m3.d). The COD removal rate of the anaerobic reactor is 80%; the sludge yield of the anaerobic reaction is 0.05kgVSS / kgCOD; the gas production rate of the anaerobic reactor is 0.3Nm 3 / kgCOD; the moisture content of the granular sludge produced by anaerobic reaction is 90%.

[0112] After three-phase separation, the biogas enters the biogas degassing tank for reuse, part of the water is discharged into the downstream biochemical treatment system, and part enters the circulating feed tank for reuse, achieving a 96.3% reduction in sludge. The amount of biogas generated during the sludge reduction process is 7.2Nm 3 .

[0113] Example 3

[0114] After dehydration, high-efficiency lysing agent and 35% sodium hydroxide aqueous solution were added to the excess sludge, wherein the moisture content of the excess sludge was 85%, the mass ratio of the high-efficiency lysing agent to the excess sludge was 0.002:1, and the mass ratio of the sodium hydroxide aqueous solution to the excess sludge was 0.002:1. Hydrolysis was carried out, the temperature of thermal hydrolysis was 165°C, the pressure of thermal hydrolysis was 7 bar, the time of thermal hydrolysis was 45 minutes, and then flash evaporation was performed, the temperature of flash evaporation was 120°C, the pressure of flash evaporation was 2 bar, and the density of the sludge hydrolyzate obtained after flash evaporation was 1300 kg / m 3 ; SCOD is 33000mg / L; water content: 92%, PH is 7.8, viscosity is 95cp, BOD / COD value is 0.45.

[0115] The sludge hydrolyzate is mixed with industrial sewage at a mass ratio of 1:125, wherein the COD of the industrial sewage is 7000 mg / L, and the BOD / COD of the industrial sewage is 0.35. The pH value is adjusted to 7-8 with sodium hydroxide solution, and urea is added. After the addition, the mass ratio of the COD equivalent of carbon to nitrogen and phosphorus in the mixed sewage is 300:6:1. It enters the anaerobic reactor for anaerobic reaction. The temperature of the anaerobic reaction is 33-35°C, the pressure of the anaerobic reaction is normal pressure, the time of the anaerobic reaction is 13h, and the organic volume load of the anaerobic reaction is 15kgCODcr / (m3.d). The COD removal rate of the anaerobic reactor is 85%; the sludge yield of the anaerobic reaction is 0.05kgVSS / kgCOD; the gas production rate of the anaerobic reactor is 0.35Nm 3 / kgCOD; the moisture content of the granular sludge produced by anaerobic reaction is 92%.

[0116] After three-phase separation, the biogas enters the biogas degassing tank for reuse, part of the water is discharged into the downstream biochemical treatment system, and part enters the circulating feed tank for reuse, achieving a sludge reduction of 94.9%. The amount of biogas generated during the sludge reduction process is 9.8Nm 3 .

[0117] In Examples 1 to 3, the dehydrated residual sludge with different water contents was treated by thermal hydrolysis, flash evaporation, mixing with industrial sewage, anaerobic reaction and separation to obtain reduced sludge. The COD removal rate of the anaerobic reactor was 80-90%, and the sludge reduction was 94.9-96.3%. The amount of biogas generated during the sludge reduction process was 7.2-12.96 Nm 3 It achieves sludge reduction and resource utilization under the condition of low energy consumption in device operation, and provides a set of reduction and resource utilization disposal solutions for the biochemical sludge generated by the enterprise's sewage treatment equipment, with significant economic benefits.

Claims

1. A method for sludge modification and anaerobic coupled reduction, comprising the following steps: (1) adding a high-efficiency lysing agent and alkali to the residual sludge after dehydration, performing thermal hydrolysis and flash evaporation treatment to obtain a sludge hydrolyzate; (2) The sludge hydrolyzate obtained in step (1) is mixed with industrial sewage, and then subjected to anaerobic reaction in an anaerobic reaction device, followed by three-phase separation to separate water and gas, thereby obtaining reduced sludge.

2. The method for sludge modification and anaerobic coupled reduction according to claim 1, characterized in that: Step (1), The moisture content of the dehydrated excess sludge is 80-90%, preferably 83-86%; and / or, The temperature of the thermal hydrolysis is 150-180°C; and / or, The pressure of the thermal hydrolysis is 6 to 8 bar; and / or, The thermal hydrolysis time is 30 to 60 minutes; and / or, The flash evaporation temperature is 110-130° C.; and / or, The flash evaporation pressure is 1 to 3 bar.

3. The method for sludge modification and anaerobic coupled reduction according to claim 1, characterized in that: Step (1), The mass ratio of the high-efficiency lytic agent to the excess sludge after dehydration is (0.001-0.003):1, preferably (0.0015-0.0025):1; and / or, The alkali is a sodium hydroxide aqueous solution, preferably a 20-40% sodium hydroxide aqueous solution. More preferably, the mass ratio of the sodium hydroxide aqueous solution to the dehydrated excess sludge is (0.001-0.003):1, preferably (0.0015-0.0025):

1.

4. The method for sludge modification and anaerobic coupled reduction according to claim 1, characterized in that: The sludge hydrolyzate obtained in step (1) has a pH value of 6-9, a viscosity of <100 cp, a moisture content of 90-92%, a SCOD of ≥30000 mg / L, preferably 30000-36000 mg / L, and a BOD / COD of ≥0.

4.

5. The method for sludge modification and anaerobic coupled reduction according to claim 1, characterized in that: Step (2), The sludge hydrolyzate obtained in step (1) is first mixed with industrial sewage and then introduced into an anaerobic reaction device to adjust the pH value. Optionally, nutrient salts are added to carry out anaerobic reaction.

6. The method for sludge modification and anaerobic coupled reduction as claimed in claim 5, characterized in that: The mass ratio of industrial wastewater to sludge hydrolysate is greater than or equal to 100; and / or, Adjust the pH value with an acid or a base; the acid is preferably one of hydrochloric acid and phosphoric acid; the base is preferably one of sodium hydroxide and calcium hydroxide; and / or, The pH value is 6 to 9, preferably 7 to 8; and / or, The nutrient salt is at least one of urea and phosphate; and / or, Before entering the anaerobic reaction device, the mass ratio of COD equivalent of carbon to nitrogen and phosphorus in the mixed sewage after the sludge hydrolyzate is mixed with industrial sewage is (200-300): (4-6):

1.

7. The method for sludge modification and anaerobic coupled reduction as claimed in claim 1, characterized in that: Step (2), The anaerobic reaction device comprises a circulating feed tank and an anaerobic reactor; the pH value is adjusted and nutrient salts are added in the circulating feed tank; and the anaerobic reaction is carried out in the anaerobic reactor.

8. The method for sludge modification and anaerobic coupled reduction as claimed in claim 7, characterized in that: The anaerobic reactor is provided with upper and lower three-phase separators, the outlet water of the lower three-phase separator is provided with an internal reflux device, the outlet water of the upper three-phase separator is provided with an external reflux device, and the outer shell of the anaerobic reactor is insulated.

9. The method for sludge modification and anaerobic coupled reduction as claimed in claim 1, characterized in that: The temperature of the anaerobic reaction is 30-40°C, preferably 33-35°C; and / or, The pressure of the anaerobic reaction is normal pressure; and / or, The organic volume load of the anaerobic reaction is 3-30 kgCODcr / (m 3 .d); and / or, The anaerobic reaction time is 10 to 16 hours.

10. A system for the method of sludge modification and anaerobic coupled reduction according to any one of claims 1 to 9, comprising a thermal hydrolysis reaction section and an anaerobic reaction section; the thermal hydrolysis reaction section comprises a sludge storage tank, a high-efficiency lysing agent dosing device, an alkali dosing device, a sludge heat exchanger, a sludge heater, a homogenization kettle, a homogenization liquid heater, a reactor, a flash kettle and a sludge hydrolyzate heat exchanger; the anaerobic reaction section comprises a regulating tank, a circulating feed tank and an anaerobic reactor; The sludge storage tank is connected to the sludge heat exchanger through a pump, the high-efficiency lysing agent dosing device and the alkali dosing device are connected to the pipeline between the sludge storage tank and the sludge heat exchanger, the sludge heat exchanger, the sludge heater, the homogenizer kettle, and the homogenizer liquid heater are connected in sequence, the homogenizer liquid heater is connected to the reactor, the reactor is connected to the flash kettle, the steam pipeline of the flash kettle is connected to the sludge storage tank, the liquid pipeline is connected to the sludge heat exchanger, the sludge heat exchanger is connected to the sludge hydrolyzate heat exchanger, the sludge hydrolyzate heat exchanger is connected to the regulating tank, the regulating tank is connected to the circulating feed tank, the circulating feed tank is provided with an acid and alkali liquid inlet and a nutrient salt dosing port, the nutrient salt dosing port is connected to the nutrient salt dosing device, the circulating feed tank is connected to the anaerobic reactor, the anaerobic reactor is provided with a biogas outlet and a water outlet, the biogas outlet is connected to the biogas degassing tank, wherein the water outlet is divided into two pipelines, one is connected to the circulating feed tank to form an external circulation, and the other is connected to the downstream biochemical treatment system.

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