A system and method for co-processing sludge and organic waste

Abstract

The application discloses a sludge and organic waste cooperative treatment system and method. The treatment system comprises a cooperative anaerobic pretreatment unit, an anaerobic digestion unit and a drying treatment unit connected in sequence; the cooperative anaerobic pretreatment unit comprises a cooperative anaerobic pre-reaction tank and a mechanical circulation pretreatment device; the anaerobic digestion unit comprises a first anaerobic digestion tank and a second anaerobic digestion tank; and the drying treatment unit comprises a sludge drying device, a sludge dewatering device and a dewatered sludge bin. The system and method realize slurry of the material, provide uniform, good rheological property and high reaction efficiency of the slurry for anaerobic digestion, further improve biogas production capacity, reduce stirring energy consumption, avoid upper scum of the anaerobic digestion tank, obtain higher gas production rate in a shorter anaerobic reaction time, and realize self-sufficiency of heat energy. Further energy utilization can be realized through natural gas production by biogas purification or biogas power generation mode, efficient treatment and heat energy balance are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to a sludge and organic waste collaborative treatment system and method. BACKGROUND

[0002] The current municipal sludge treatment rate is still not high. Sludge treatment has many problems such as high investment cost, high technical difficulty, lack of guidance, etc., among which the treatment cost is one of the most critical problems.

[0003] According to the end disposal, sludge disposal includes land use, drying incineration, building material utilization, etc. Among them, sludge after treatment realizes land use or drying incineration, which is the mainstream technology at home and abroad. The sludge treatment process before disposal is divided into two categories: anaerobic stabilization and non-anaerobic stabilization. Whether to adopt anaerobic stabilization mainly depends on the development level and the degree of technology.

[0004] For this, the prior art sorts and crushes the above-mentioned organic waste and combines it with municipal sludge for treatment under the condition of electric heating, which is similar to dry anaerobic digestion reaction. However, the gas production rate of the unit organic matter is low, and the energy consumption is large, in addition, the product outlet is limited, and the overall efficiency is low.

[0005] How to efficiently treat sludge and organic waste and realize stabilization and resource utilization on the basis of low carbon and technology popularization is a difficult problem to be solved at present. SUMMARY

[0006] The present application is to solve the defects of high investment cost, poor running stability, poor end outlet and high energy consumption of dispersed treatment of sludge and organic waste, and proposes a sludge and organic waste collaborative treatment system and method. Under the premise of realizing high-standard sludge stabilization, the present application realizes self-heating balance as a whole, uses the produced biogas as the energy of the system itself to realize the self-heating balance of digestion and drying; the system and method of the present application can improve the biogas production capacity, get higher gas production rate in a shorter anaerobic reaction time, and realize efficient treatment of sludge and organic waste, solving the problem of multi-source sludge and organic waste treatment and disposal; it can also realize the heat balance in the system, reducing the heat consumption of the system.

[0007] The present application solves the above-mentioned problems by the following technical solutions.

[0008] The present application provides a sludge and organic waste collaborative treatment system, which comprises a collaborative anaerobic pretreatment unit, an anaerobic digestion unit and a drying treatment unit connected in sequence.

[0009] The synergistic anaerobic pretreatment unit comprises a synergistic anaerobic pre-reaction tank and a mechanical circulation pretreatment device for liquefying raw material slurry; the synergistic anaerobic pre-reaction tank comprises a raw material inlet for introducing sludge and organic waste into the synergistic anaerobic pre-reaction tank; the outlet of the synergistic anaerobic pre-reaction tank is connected with the inlet of the mechanical circulation pretreatment device through a heat exchange pipeline, and the outlet of the mechanical circulation pretreatment device is connected with the inlet of the synergistic anaerobic pre-reaction tank, forming a circulation pretreatment loop of raw materials; on the heat exchange pipeline, a first heat exchanger and a second heat exchanger are sequentially arranged along the flow direction of the materials.

[0010] The anaerobic digestion unit comprises a first anaerobic digestion tank and a second anaerobic digestion tank; the first anaerobic digestion tank is connected with the synergistic anaerobic pre-reaction tank; the gas phase outlet of the first anaerobic digestion tank and the gas phase outlet of the second anaerobic digestion tank are both connected with the fuel gas inlet of a steam boiler for providing fuel for the steam boiler; the steam outlet of the steam boiler is connected with the synergistic anaerobic pre-reaction tank and the drying treatment unit through a first steam pipeline and a second steam pipeline, respectively.

[0011] The drying treatment unit comprises a sludge drying device, and the feed inlet of the sludge drying device is connected with the discharge outlet of the second anaerobic digestion tank; the hot fluid outlet of the sludge drying device is connected with the first heat exchanger through a first heat exchange medium pipeline, and the steam condensate water outlet of the sludge drying device is connected with the second heat exchanger through a second heat exchange medium pipeline.

[0012] In the present application, the hot fluid is tail gas obtained after heating of sludge in the sludge drying device, which contains a small amount of particulate sludge and steam.

[0013] In the present application, the first heat exchange medium pipeline provides heat from the above-mentioned tail gas to the heat exchange pipeline.

[0014] In the present application, the steam condensate water is obtained after heat exchange of superheated steam from the second steam pipeline.

[0015] In the present application, the second heat exchange medium pipeline provides heat from the steam condensate water after heat exchange to the heat exchange pipeline.

[0016] In the present application, the temperature of the steam condensate water in the second heat exchange medium pipeline is higher than the temperature of the tail gas in the first heat exchange medium pipeline; the first heat exchange medium pipeline and the second heat exchange medium pipeline respectively pass through the first heat exchanger and the second heat exchanger to provide gradually rising heat to the materials in the heat exchange pipeline.

[0017] In some embodiments, the synergistic anaerobic pre-reaction tank further comprises an industrial water inlet and / or a composite medicament inlet.

[0018] In the present application, the first anaerobic digester is used for anaerobic digestion reaction, and the second anaerobic digester is used for anaerobic digestion reaction and also used for providing buffering function.

[0019] In the present application, the anaerobic digestion unit can maximize the production of biogas; after the raw material flow property is improved by the synergistic anaerobic pretreatment unit, all the generated biogas can be maximally collected and efficiently treated in the anaerobic digestion unit.

[0020] In the present application, the first steam pipeline and the second steam pipeline respectively provide the synergistic anaerobic pretreatment tank and the drying treatment unit with heat from the superheated steam of the steam boiler.

[0021] In some embodiments, the drying treatment unit further comprises a sludge dewatering device and a dewatered sludge bin, and the second anaerobic digester is sequentially connected with the sludge dewatering device, the dewatered sludge bin and the sludge drying equipment.

[0022] In some embodiments, the synergistic treatment system of sludge and organic waste further comprises a biogas storage and purification unit, an inlet of the biogas storage and purification unit is connected with a gas phase outlet of the first anaerobic digester and a gas phase outlet of the second anaerobic digester respectively, for storing and purifying the generated biogas after anaerobic digestion; and a fuel gas outlet of the biogas storage and purification unit is connected with the steam boiler.

[0023] In specific embodiments, a liquid phase outlet of the sludge dewatering device is provided with a drainage port.

[0024] In specific embodiments, a waste gas outlet of the biogas storage and purification unit is further connected with an excess gas combustion tower, and the excess gas combustion tower is provided with an exhaust port.

[0025] In the present application, the sludge drying equipment is generally arranged in a sludge drying workshop; and those skilled in the art should know that the sludge drying workshop further comprises other sludge drying supporting equipment.

[0026] The present application further provides a synergistic treatment method of sludge and organic waste, which adopts the synergistic treatment system of sludge and organic waste as described above, and comprises the following steps:

[0027] S1, in the synergistic anaerobic pretreatment tank, the raw material is mixed with the superheated steam in the first steam pipeline, the raw material comprises sludge and organic waste; and the mechanical circulation pretreatment device is started to perform circulation pretreatment, to obtain slurry-liquefied material;

[0028] S2, the slurry material is introduced into an anaerobic digestion unit to perform secondary anaerobic digestion reaction in the first anaerobic digestion tank and the second anaerobic digestion tank in sequence, to obtain biogas and digestion liquid;

[0029] S3, the biogas is introduced into the steam boiler to perform combustion, to obtain superheated steam, and the superheated steam is introduced into the heat medium inlet of the synergistic anaerobic pre-reaction tank and the sludge drying device through the first steam pipeline and the second steam pipeline respectively;

[0030] S4, the digestion liquid is introduced into the sludge drying device to perform heating and drying through the superheated steam in the second steam pipeline, to obtain dried sludge, tail gas and steam condensate water;

[0031] S5, the tail gas is introduced into the first heat exchanger through the first heat exchange medium pipeline, and the steam condensate water is introduced into the second heat exchanger through the second heat exchange medium pipeline.

[0032] In the field, the anaerobic digestion reaction of sludge generally includes anaerobic hydrolysis, acidification, methanation and other stages, wherein the anaerobic hydrolysis breaks the organic macromolecules to produce medium molecular weight organic matter, and this step is a rate-limiting reaction affecting the reaction time of the whole anaerobic digestion reaction.

[0033] In the present application, the slurry material is ground by mechanical and thermal circulation, preferably combined with chemical methods, which is equivalent to completing the crushing and partial hydrolysis of a part of the agglomerated bacteria and organic lumps in advance, thereby shortening the residence time of the subsequent anaerobic digestion reaction.

[0034] In step S1 of the present application, the waste composed of sludge and organic waste includes water and solid suspensions, and specifically contains the following components: inorganic minerals, organic matter, heavy metals, pathogens and pathogenic microorganisms, protozoa and metazoans, insect eggs and adult insects, etc.

[0035] In the present application, the addition amount of the organic waste is generally more than 10% of the total mass of the sludge, so as to increase the organic matter content in the sludge.

[0036] In step S1 of the present application, preferably, before introducing the raw material containing sludge and organic waste into the synergistic anaerobic pre-reaction tank, the block-shaped inorganic impurities in the raw material are removed; more preferably, the block-shaped inorganic impurities include one or more of wood, metal, ceramic and glass.

[0037] In some embodiments, in step S1, the organic matter content of the raw material is 60% or more.

[0038] In some embodiments, in step S1, the solid content (TS) of the raw material is 5-15%.

[0039] In some embodiments, in step S1, the sludge comprises municipal sludge; the municipal sludge is conventional in the art, and refers to solid precipitated matter generated in the sewage treatment process of a sewage treatment plant, and the main characteristic is that the dewatered sludge has a water content of about 80%.

[0040] In some embodiments, in step S1, the organic waste comprises one or more of kitchen garbage, industrial organic garbage, agricultural organic waste, aquatic plant waste, and livestock and poultry manure.

[0041] In some embodiments, in step S1, the superheated steam directly heats the raw material in a spraying manner.

[0042] In some embodiments, in step S1, the circulating pretreatment comprises one or more of grinding treatment, microwave treatment, and ultrasonic treatment; the above-mentioned device is used to grind, microwave, or ultrasonically treat the material, so as to realize slurry of the material, promote the decrease of the viscosity of the material, control the energy consumption of anaerobic digestion stirring within a reasonable range, and realize energy-saving operation.

[0043] In the present application, through the synergistic anaerobic pretreatment of sludge and organic waste, the material does not need to add an alkaline agent to adjust the pH value or the degree of acidity and alkalinity during digestion.

[0044] In some embodiments, in step S1, the raw material further comprises industrial water and / or a medicament, and the medicament is used to strengthen hydrolysis conditioning; preferably, the medicament comprises one or more of an oxidizing medicament and / or an alkaline medicament; more preferably, the medicament comprises one or more of an iron salt, hydrogen peroxide, and an ozone water solution; by adding the above-mentioned auxiliary medicament, specific organic waste such as agricultural straw and river aquatic plants can be targetedly solved, hydrolysis conditioning is strengthened, and biogas production capacity is improved.

[0045] In some embodiments, in step S1, the temperature of the superheated steam in the first steam pipeline is 160-200℃.

[0046] In step S1 of the present application, the raw material is subjected to conditioning pretreatment and slurry in the synergistic anaerobic pretreatment tank.

[0047] In some embodiments, in step S1, the residence time of the raw material in the synergistic anaerobic pretreatment tank is 12-24h.

[0048] In some embodiments, in step S1, the proportion of the raw material subjected to circulating pretreatment is 10-100 wt%, and the percentage is the mass ratio of the material subjected to circulating pretreatment to the total mass of the raw material.

[0049] In step S1 of the present application, the raw material is subjected to the cyclic pretreatment by adding steam into the synergistic anaerobic pre-reaction tank and starting the mechanical circulation pretreatment device, so as to realize the conditioning pretreatment and slurry of the raw material; after the whole synergistic treatment system is started, the tail steam and steam condensate water of step S5 are used to provide heat for the circulating raw material.

[0050] In the present application, the mixture of the raw material is subjected to the conditioning treatment by using the mechanical and thermal force, and preferably by using the means including the medicament and industrial water, so as to realize the slurry of the material, and to provide the uniform, good rheological property and high reaction efficiency of the slurry for the anaerobic digestion.

[0051] In the present application, according to the properties of the material and the design working condition of the system, the pretreatment system and the secondary anaerobic digestion can be operated in the high-temperature anaerobic mode or in the mesophilic anaerobic mode.

[0052] In some embodiments, in step S1, the temperature of the synergistic anaerobic pre-reaction tank is 40-90℃.

[0053] In a specific embodiment, when the secondary anaerobic digestion reaction is carried out at mesophilic temperature, the temperature of the synergistic anaerobic pre-reaction tank is 42-60℃.

[0054] In a specific embodiment, when the secondary anaerobic digestion reaction is carried out at high temperature, the temperature of the synergistic anaerobic pre-reaction tank is 58-90℃.

[0055] In the present application, after the anaerobic digestion reaction, the volatile organic matter is subjected to the anaerobic hydrolysis, acidification and methanation reactions; wherein the main products of the macromolecular organic matter include methane and carbon dioxide, and the by-products include the organic matter with medium molecular weight and small molecular weight, such as humic acid, small molecular volatile acid and the like.

[0056] In some embodiments, in step S2, the temperature of the first anaerobic digestion tank is 30-60℃.

[0057] In a specific embodiment, when the secondary anaerobic digestion reaction is carried out at mesophilic temperature, the temperature of the first anaerobic digestion tank is 32-38℃.

[0058] In a specific embodiment, when the secondary anaerobic digestion reaction is carried out at high temperature, the temperature of the first anaerobic digestion tank is 52-58℃.

[0059] In some embodiments, in step S2, the temperature of the second anaerobic digestion tank is 30-60℃.

[0060] In a specific embodiment, when the secondary anaerobic digestion reaction is carried out at mesophilic temperature, the temperature of the second anaerobic digestion tank is 32-38℃.

[0061] In a specific embodiment, when the secondary anaerobic digestion reaction is carried out at high temperature, the temperature of the second anaerobic digestion tank is 52-58℃.

[0062] In some embodiments, in step S2, the temperature of the first anaerobic digestion tank and the second anaerobic digestion tank is the same.

[0063] In a specific embodiment, when the temperature of the first anaerobic digestion tank and the second anaerobic digestion tank ranges from 32-38℃, the digestion time of the slurry material is 20 days or more.

[0064] In a specific embodiment, when the temperature of the first anaerobic digestion tank and the second anaerobic digestion tank ranges from 52-58℃, the digestion time of the slurry material is 15 days or more.

[0065] In step S2 of the present application, preferably, the volatile solid load of the sludge and organic waste co-treatment system is 2-3 kg VS / (m 3 ·d); in this case, the unit organic matter biogas production capacity is 0.4-0.6 Nm 3 per kg of volatile solid feed. The volatile solid load refers to the amount of volatile solid added to the digestion tank per day divided by the working volume of the digestion tank.

[0066] In the present application, the slurry material is fed into the anaerobic digestion unit by using the conventional pump delivery method in the art.

[0067] In some embodiments, in step S2, the solid content of the slurry material is not more than 12%, preferably 10-12%.

[0068] In some embodiments, in step S2, the pH value of the first anaerobic digestion tank is 6.5-7.5.

[0069] In some embodiments, in step S2, the pH value of the second anaerobic digestion tank is 6.5-7.5.

[0070] In some embodiments, in step S2, the unit mechanical stirring energy consumption in the first anaerobic digestion tank or the second anaerobic digestion tank is 4-8 W / m 3 .

[0071] In some embodiments, in step S2, the temperature difference in the first anaerobic digestion tank is not more than 3℃.

[0072] In some embodiments, in step S2, the temperature difference in the second anaerobic digestion tank is not more than 5℃.

[0073] In some embodiments, in step S2, the biogas is stored in a biogas storage and purification unit after purification treatment, and the excess gas is introduced into an excess gas combustion tower.

[0074] In specific embodiments, in step S2, the biogas can be a general crude biogas in the art, and the methane content is 55-95%.

[0075] In specific embodiments, in step S2, after purification treatment, the methane content in the biogas is 75% or more; and the methane content in the biogas is increased by feeding of the organic waste.

[0076] In specific embodiments, in step S2, after purification treatment, the hydrogen sulfide content in the biogas is less than 20 mg / Nm 3 .

[0077] In the present application, the superheated steam is supplied to heat users through the first steam pipeline and the second steam pipeline, respectively.

[0078] In some embodiments, in step S3, the temperature of the superheated steam in the second steam pipeline is 160-200℃.

[0079] In the present application, the biogas is used for boiler combustion to generate steam, and therefore the impurity content needs to be controlled.

[0080] In some embodiments, in step S3, the biogas is introduced into the steam boiler for combustion after being purified in the biogas storage and purification unit; after passing through the biogas storage and purification unit, the biogas is purified to reduce the impurity content such as water, hydrogen sulfide, carbon dioxide, etc., to achieve dehydration, desulfurization and decarburization, to ensure the methane content in the purified product, and to make the atmospheric pollutants of the boiler meet the emission requirements.

[0081] In some embodiments, in step S3, when the feeding of organic matter is more than 60% or more, the system design of the biogas storage and purification unit can increase the biogas purification to produce natural gas or biogas power generation for self-use to balance the excess energy.

[0082] In the present application, after dehydration and drying treatment of the digestion liquid, no more than 50% of the material is subjected to further decomposition reaction.

[0083] In the present application, the heat for heating and drying is provided by the superheated steam of the second steam pipeline, and the superheated steam of the second steam pipeline forms steam condensate water after heat exchange; the dehydrated sludge is subjected to heat drying treatment to produce tail gas containing a small amount of granular sludge and steam.

[0084] In the present application, in step S4, the sludge drying equipment can include a single-stage dryer, and the heating and drying can be performed in the single-stage dryer.

[0085] In the present application, in step S4, the sludge drying can adopt an indirect heat exchange mode, and steam provides heat for the sludge through a jacket or a heat exchanger.

[0086] In some embodiments, in step S4, the temperature of the tail steam is 92-98℃.

[0087] In some embodiments, in step S4, the tail steam is in a negative pressure state of -4~-6kPa.

[0088] In some embodiments, in step S4, the temperature of the steam condensate is 100-140℃.

[0089] In some embodiments, in step S4, before the heating and drying, the digestion liquid is subjected to a dewatering treatment to obtain digestion sludge; preferably, under the premise of adding a polyacrylamide (PAM) conditioner, the moisture content of the digestion sludge is 80% or less. After the dewatering treatment, the material entering the drying treatment unit is further stabilized, reduced, and reaches a dry biogas residue product that meets the hygiene standards, which can be used as a material for land use.

[0090] In the present application, since the sludge and organic waste contain toxic pollutants such as PCB, PCDD, PFAS, heavy metals, pathogens, and disease vectors, direct discharge or land use is easy to cause diseases or easy to cause an outbreak of epidemics, and pollute the food chain. The national standard CJ / T510-2017 "Sludge Treatment and Stabilization Standard for Municipal Wastewater Treatment Plant" provides that the standard for sludge stabilization is to achieve the hygiene requirements of not easy to rot and stink, control pathogens, etc.; the United States stipulates the requirements for A-level sludge products through EPA503 clauses.

[0091] In some embodiments, in step S4, the moisture content of the dried sludge is less than 25%, which meets the hygiene requirements of the above national standard and international industry; and the solid content of the dried sludge is 75% or more, so that the dried sludge has stability and meets the control index of fecal coliform bacteria in the sludge stabilization standard.

[0092] In the present application, the tail steam and the steam condensate are used as recoverable heat energy for the conditioning of the circulating pretreatment.

[0093] In the present application, the excess energy balance of the sludge and organic waste co-processing system can be realized in the form of an excess gas combustion tower and the condensate discharge of waste heat utilization.

[0094] In the present application, the tail gas and the steam condensate water can be recovered and the waste heat of the superheated steam in the second steam pipeline of the sludge drying device is input, which accounts for 50-60% of the total heat energy of the superheated steam input in the second steam pipeline; the available net heat energy of the synergistic anaerobic pre-reaction tank accounts for about 25-35% of the total heat energy of the superheated steam input in the second steam pipeline in the heating and drying process, so that the heat energy balance of the whole system can be realized, and the system can be designed to realize automatic operation through self-learning feedback control.

[0095] In the present application, the treatment process of the dried sludge is conventional disinfection and sterilization in the art, and finally forms a mixture of organic solids and inorganic solids, and water.

[0096] On the basis of common sense in the art, the above-mentioned preferred conditions can be combined arbitrarily, that is, to obtain each preferred example of the present application.

[0097] The reagents and raw materials used in the present application are commercially available.

[0098] The positive progress effect of the present application is:

[0099] ①The present application can realize volume reduction and weight reduction by removing water from sludge, so as to achieve reduction, and the finally obtained dried sludge meets the health requirements of national standards and international industry, realizes stabilization, and at the same time realizes the treatment goals of harmlessness and resource utilization.

[0100] ②The system and method of the present application utilize machinery and heat to adjust and treat the mixed materials of the feed, realize slurry of the materials, provide uniform, good rheological property and high reaction efficiency of the slurry for anaerobic digestion, and further improve biogas production capacity, reduce stirring energy consumption, avoid the production of upper scum in the anaerobic digestion tank, and obtain higher gas production rate in a shorter anaerobic reaction time.

[0101] ③It is difficult to realize heat energy balance by separately carrying out sludge anaerobic treatment and then drying, and it is difficult to realize long-term stable operation by separately carrying out anaerobic digestion of organic waste; the present application utilizes low-carbon synergistic treatment of sludge and organic waste, realizes stable production and self-sufficiency of heat energy, has surplus biogas production capacity under the condition of sufficient and stable supply of organic waste, and realizes further energy utilization through natural gas production by biogas purification or biogas power generation, and realizes efficient treatment and balance of heat energy.

[0102] ④In the system and method of the present application, the heat drying treatment technology after the synergistic anaerobic treatment of sludge and organic matter can effectively solve the problems in the treatment and disposal of multi-source sludge or organic waste; the hygienically qualified product after treatment can be used as raw material for land use or blending and burning disposal, building material utilization, and the investment and cost of comprehensive treatment are greatly reduced compared with separate treatment. BRIEF DESCRIPTION OF DRAWINGS

[0103] Figure 1 Structure diagram of a sludge and organic waste co-processing system according to Example 1.

[0104] Explanation of reference numerals:

[0105] Co-anaerobic pretreatment unit 1

[0106] Co-anaerobic pretreatment tank 101

[0107] Feedstock inlet 1011

[0108] Mechanical circulation pretreatment device 102

[0109] First heat exchanger 103

[0110] Second heat exchanger 104

[0111] Anaerobic digestion unit 2

[0112] First anaerobic digester 201

[0113] Second anaerobic digester 202

[0114] Drying treatment unit 3

[0115] Sludge drying device 301

[0116] Sludge dewatering device 302

[0117] Dewatered sludge bin 303

[0118] Steam boiler 401

[0119] Biogas storage and purification unit 501

[0120] Excess gas combustion tower 601

[0121] Heat exchange pipeline 1000

[0122] First steam pipeline 1001

[0123] Second steam pipeline 1002

[0124] First heat exchange medium pipeline 1003

[0125] Second heat exchange medium pipeline 1004

[0126] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. DETAILED DESCRIPTION

[0127] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0128] Embodiments 1-4 of this application all employ the following... Figure 1 The system shown is a co-processing system for sludge and organic waste. Figure 1 This is a schematic diagram of the processing system.

[0129] The sludge and organic waste co-treatment system includes a co-anaerobic pretreatment unit 1, an anaerobic digestion unit 2, and a drying unit 3 connected in sequence.

[0130] The co-anaerobic pretreatment unit 1 includes a co-anaerobic pre-reaction tank 101 and a mechanical circulation pretreatment device 102 for liquefying the raw material slurry. The co-anaerobic pre-reaction tank 101 includes a raw material inlet 1011, which is used to introduce sludge and organic waste into the co-anaerobic pre-reaction tank 101. The outlet of the co-anaerobic pre-reaction tank 101 is connected to the inlet of the mechanical circulation pretreatment device 102 through a heat exchange pipeline 1000, and the outlet of the mechanical circulation pretreatment device 102 is connected to the inlet of the co-anaerobic pre-reaction tank 101, forming a circulating pretreatment loop for the raw material. On the heat exchange pipeline 1000, a first heat exchanger 103 and a second heat exchanger 104 are sequentially arranged along the flow direction of the material.

[0131] Anaerobic digestion unit 2 includes a first anaerobic digester 201 and a second anaerobic digester 202; the first anaerobic digester 201 is connected to a co-anaerobic pre-reaction tank 101; the gas phase outlet of the first anaerobic digester 201 and the gas phase outlet of the second anaerobic digester 202 are both connected to the fuel gas inlet of the steam boiler 401 to provide fuel for the steam boiler 401; the steam outlet of the steam boiler 401 is connected to the co-anaerobic pre-reaction tank 101 and the drying treatment unit 3 through the first steam pipe 1001 and the second steam pipe 1002 respectively to provide heat.

[0132] The drying treatment unit 3 includes a sludge drying device 301. The inlet of the sludge drying device 301 is connected to the outlet of the second anaerobic digester 202. The hot fluid outlet of the sludge drying device 301 is connected to the first heat exchanger 103 through the first heat exchange medium pipeline 1003. The steam condensate outlet of the sludge drying device 301 is connected to the second heat exchanger 104 through the second heat exchange medium pipeline 1004, which is used to supply heat to the material in the heat exchange pipeline 1000.

[0133] The synergistic anaerobic pre-reaction tank 101 also includes an industrial water inlet and / or a compound reagent inlet.

[0134] The sludge drying treatment unit 3 further comprises a sludge dewatering device 302 and a dewatered sludge bin 303, and the second anaerobic digester 202 is connected with the sludge dewatering device 302, the dewatered sludge bin 303 and the sludge drying device 301 in sequence.

[0135] The sludge and organic waste cooperative treatment system further comprises a biogas storage and purification unit 501, the inlet of the biogas storage and purification unit 501 is connected with the gas phase outlet of the first anaerobic digester 201 and the gas phase outlet of the second anaerobic digester 202 respectively, for storing and purifying the biogas generated after anaerobic digestion; and the fuel gas outlet of the biogas storage and purification unit 501 is connected with the steam boiler 401.

[0136] The liquid phase outlet of the sludge dewatering device 302 is provided with a water outlet.

[0137] The waste gas outlet of the biogas storage and purification unit 501 is further connected with the residual gas combustion tower 601, and the residual gas combustion tower 601 is provided with an exhaust port.

[0138] Embodiment 1

[0139] The embodiment is a sludge and organic waste cooperative treatment method, which adopts the sludge and organic waste cooperative treatment system as described above, and comprises the following steps:

[0140] S1, municipal sludge, kitchen garbage or organic industrial garbage, agricultural waste or livestock manure is mixed after removing inorganic impurities as raw materials for the cooperative anaerobic system, and at least one or more organic waste is used as raw material except for municipal sludge; the pretreatment method of the embodiment comprises mechanical grinding and thermal conditioning: in the cooperative anaerobic pre-reaction tank 101, the raw materials are mixed with the superheated steam in the first steam pipeline 1001, the raw materials contain sludge and organic waste, the mechanical circulation pretreatment device 102 is opened for mechanical grinding and circulation pretreatment, and the slurry material is obtained;

[0141] S2, the slurry material is introduced into the anaerobic digestion unit 2, and two-stage anaerobic digestion reaction is carried out in the first anaerobic digester 201 and the second anaerobic digester 202 in sequence, and biogas and digestion liquid are obtained;

[0142] S3, the biogas is introduced into the steam boiler 401 for combustion, and the superheated steam is introduced into the heat medium inlets of the cooperative anaerobic pre-reaction tank 101 and the sludge drying device 301 through the first steam pipeline 1001 and the second steam pipeline 1002 respectively;

[0143] S4, the digestion liquid is introduced into the sludge drying device 301, and is heated and dried by the superheated steam in the second steam pipeline 1002, and dried sludge, tail gas and steam condensate are obtained;

[0144] S5, the tail gas enters the first heat exchanger 103 through the first heat exchange medium pipeline 1003; the steam condensate enters the second heat exchanger 104 through the second heat exchange medium pipeline 1004, and supplies heat for the material in the heat exchange pipeline 1000.

[0145] In step S1, the organic matter content of the raw material is greater than or equal to 60%, the solid content of the raw material is 5-15%, the steam heats the raw material in the form of injection in the start-up stage, the circulating pretreatment includes grinding treatment; the temperature of the superheated steam in the first steam pipeline 1001 is 180℃; in the synergistic anaerobic pre-reaction tank 101, the residence time of the raw material is 12h; the circulating pretreated raw material accounts for 25 wt%, and the percentage is the mass ratio of the circulating pretreated material to the total mass of the raw material.

[0146] In step S1, the temperature in the synergistic anaerobic pre-reaction tank 101 ranges from 45℃.

[0147] The present embodiment adopts a pretreatment and tempering operation mode of mesophilic anaerobic digestion, and the temperature of the first anaerobic digestion tank 201 and the second anaerobic digestion tank 202 ranges from 35±3℃, and the digestion time of the slurry material is 20 days.

[0148] In step S2, the volatile solid load of the sludge and organic waste synergistic treatment system is 2-3 kg VS / (m 3 ·d); the unit organic matter biogas production capacity is 0.4-0.6Nm 3 ·kg volatile solid feed; the solid content of the slurry material is not more than 10-12%; the pH value of the first anaerobic digestion tank 201 and the second anaerobic digestion tank 202 is controlled in the range of 6.5-7.2; the unit mechanical stirring energy consumption in the first anaerobic digestion tank 201 or the second anaerobic digestion tank 202 is 4-8W / m 3 ; the temperature difference in the first anaerobic digestion tank 201 and the temperature difference in the second anaerobic digestion tank 202 are not more than 3℃; the biogas is stored in the biogas storage and purification unit 501 after purification treatment, and the excess gas enters the excess gas combustion tower 601; the biogas is general crude biogas, and the methane content is 55-95%; after dehydration, desulfurization and decarburization, the methane content in the biogas is 75% and above, and the hydrogen sulfide content in the biogas is less than 20mg / Nm 3 .

[0149] In step S3, the temperature of the superheated steam generated by the boiler is 180℃; the biogas is burned in the steam boiler 401 from the biogas storage and purification unit 501; after the biogas storage and purification unit 501, the biogas realizes dehydration, desulfurization and decarburization; when the organic matter in the feed is more than 60%, the system design of the biogas storage and purification unit 501 can increase the production of natural gas or biogas power generation for self-use to balance the excess energy.

[0150] In step S4, the sludge drying device 301 can include a single-stage dryer, and the heating drying can be performed in the single-stage dryer; the temperature of the tail gas is 92-98℃, and the tail gas is in a negative pressure state of-4~-6kPa; the temperature of the steam condensate water is 100-140℃; the digestion liquid is subjected to dewatering treatment to obtain the digestion sludge before the heating drying; and the moisture content of the dewatered digestion sludge is 80% or less under the premise of adding a polyacrylamide (PAM) conditioner.

[0151] If the way of the mesophilic anaerobic digestion in the embodiment is adjusted to a high-temperature anaerobic digestion way, the temperature range of the first anaerobic digestion tank 201 and the second anaerobic digestion tank 202 is 55-58℃, the temperature range of the synergistic anaerobic pre-reaction tank 101 is 65℃, and the digestion time of the slurry-ized material is 15 days; the effect of the subsequent treatment is the same as that of the embodiment.

[0152] Embodiment 2

[0153] The embodiment is a method for synergistically treating sludge and organic waste; different from embodiment 1, in step S1 of the embodiment, in the pretreatment process, Mixing iron salt as a composite agent with raw materials on the basis of mechanical grinding + thermal conditioning Mixing hydrogen peroxide or ozone water solution as a composite agent with raw materials on the basis of mechanical grinding + thermal conditioning hydrogen sulfide generated by the anaerobic reaction, and other steps are the same as those of embodiment 1.

[0154] Embodiment 3

[0155] The embodiment is a method for synergistically treating sludge and organic waste; different from embodiment 1, in step S1 of the embodiment, in the pretreatment process, Cyclic pretreatment by microwave or ultrasonic crushing + thermal conditioning ​ to condition the raw material and solve the specific difficult-to-hydrolyze organic matter in the feedstock, and other steps are the same as those of embodiment 1.

[0156] Embodiment 4

[0157] The embodiment is a method for synergistically treating sludge and organic waste; different from embodiment 1, in step S1 of the embodiment, in the cyclic pretreatment process, a microwave or ultrasonic device is used instead of the mechanical crushing and grinding way of embodiment 1, that is, ​ and other steps are the same as those of embodiment 1.

[0158] Effects of embodiments 1-4

[0159] The co-treatment method of sludge and organic waste described in Examples 1-4 was adopted. The organic matter content of the raw materials was required to be ≥60%, and the solids content was required to be ≤15%. Equipment sizes were used under operating conditions a, b, c, and d, with an organic matter content of 60% and a solids content of 15%. The average processing capacity of the system for the raw materials under different equipment sizes was calculated, and the biogas production under each operating condition was estimated. The results are shown in Table 1.

[0160] Table 1

[0161]

[0162] Table 1 shows the treatment results of sludge and waste under different operating conditions using any of the methods in Examples 1-4, which can cover the vast majority of application scenarios.

[0163] Using the system and method of this invention, when the average processing capacities are 4 tTS / d, 8 tTS / d, 12 tTS / d, and 16 tTS / d (where tTS / d refers to the tons of solid waste processed per day), the biogas production can reach 960 Nm³. 3 1920 Nm 3 2880 Nm 3 3840 Nm 3 That's all. Furthermore, in step S4, the resulting dried sludge has a moisture content of less than 25% and a solids content of 75% or higher, meeting national standards and international industry hygiene requirements.

[0164] In addition, by recovering the drying tail steam and the steam condensate, and passing the waste heat after superheated steam heat exchange into the second steam pipe of the sludge drying equipment, the waste heat accounts for 50-60% of the total heat energy input by the superheated steam in the second steam pipe; the usable net heat energy of the synergistic anaerobic pre-reaction tank accounts for about 25-35% of the total heat energy input by the superheated steam in the second steam pipe during the heating and drying process, so that the heat energy balance of the whole system can be achieved. The system can be designed with self-learning feedback control to achieve automated operation.

[0165] Comparative Example 1

[0166] The comparative example treats sludge and kitchen waste, with the same composition as in Example 1. It employs conventional dry anaerobic digestion (raw material solids content 20%~40%), simply mixing the materials before anaerobic digestion. The retention time in the mesophilic anaerobic digester is typically designed to be 25-35 days; in actual production, after exceeding 35 days, the gas production rate is approximately 0.3 Nm³. 3 / kgVS.

[0167] Comparative Example 2

[0168] The treatment object of the present comparative example is municipal sludge, and a conventional wet mesophilic anaerobic digestion (raw material solid content of 10% to 15%) is adopted. The treatment object is simply mixed and then subjected to anaerobic digestion, and the residence time required for achieving a gas production rate of 0.3 Nm 3 / kgVS is 22 days.

[0169] In comparison, after sludge slurry is liquefied, the organic matter gas production rate of the present application can reach 0.4-0.6 Nm 3 / kgVS when the residence time of mesophilic anaerobic digestion is 22 days, or the gas production rate reaches 0.3 Nm 3 / kgVS, and the residence time only needs to be about 15 days.

[0170] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any ordinary skilled person in the art can make changes, substitutions or combinations within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for the co-treatment of sludge and organic waste, characterized in that, It employs a synergistic treatment system for sludge and organic waste; the synergistic treatment system for sludge and organic waste includes a synergistic anaerobic pretreatment unit, an anaerobic digestion unit, and a drying unit connected in sequence; The co-anaerobic pretreatment unit includes a co-anaerobic pre-reaction tank and a mechanical circulation pretreatment device for liquefying the raw material slurry. The co-anaerobic pre-reaction tank includes a raw material inlet for introducing sludge and organic waste into the tank. The outlet of the co-anaerobic pre-reaction tank is connected to the inlet of the mechanical circulation pretreatment device via a heat exchange pipeline, and the outlet of the mechanical circulation pretreatment device is connected to the inlet of the co-anaerobic pre-reaction tank, forming a circulating pretreatment loop for the raw material. A first heat exchanger and a second heat exchanger are sequentially arranged along the flow direction of the material on the heat exchange pipeline. The anaerobic digestion unit includes a first anaerobic digester and a second anaerobic digester; the first anaerobic digester is connected to the co-anaerobic pre-reaction tank; the gas phase outlet of the first anaerobic digester and the gas phase outlet of the second anaerobic digester are both connected to the fuel gas inlet of the steam boiler to provide fuel for the steam boiler; the steam outlet of the steam boiler is connected to the co-anaerobic pre-reaction tank and the drying treatment unit through a first steam pipe and a second steam pipe, respectively. The drying unit includes a sludge drying device, the inlet of which is connected to the outlet of the second anaerobic digester; the hot fluid outlet of the sludge drying device is connected to the first heat exchanger via a first heat exchange medium pipeline, and the steam condensate outlet of the sludge drying device is connected to the second heat exchanger via a second heat exchange medium pipeline; the hot fluid comes from the tail steam obtained after heating the sludge in the sludge drying device. Includes the following steps: S1. In the synergistic anaerobic pre-reaction tank, the raw materials are mixed with superheated steam in the first steam pipe. The raw materials include sludge and organic waste. The mechanical circulation pretreatment device is then activated for circulation pretreatment to obtain slurry-liquefied material. The solid content of the raw materials is 5-15%; the temperature of the synergistic anaerobic pre-reaction tank is 40-90℃; S2. The slurry-liquefied material is fed into the anaerobic digestion unit, and secondary anaerobic digestion reaction is carried out in the first anaerobic digester and the second anaerobic digester in sequence to obtain biogas and digestate. The temperatures of the first anaerobic digester and the second anaerobic digester are the same; S3. The biogas is fed into the steam boiler for combustion to obtain superheated steam. The superheated steam is then fed into the synergistic anaerobic pre-reaction tank and the heat medium inlet of the sludge drying equipment through the first steam pipe and the second steam pipe, respectively. S4. The digestion liquid is introduced into the sludge drying equipment and heated and dried by superheated steam in the second steam pipe to obtain dried sludge, tail steam and steam condensate. The temperature of the superheated steam in the second steam pipe is 160-200℃; the temperature of the tail steam is 92-98℃; and the temperature of the steam condensate is 100-140℃. S5. The exhaust steam enters the first heat exchanger through the first heat exchange medium pipeline; the steam condensate enters the second heat exchanger through the second heat exchange medium pipeline.

2. The method for co-treatment of sludge and organic waste as described in claim 1, characterized in that, In step S1, the temperature of the superheated steam in the first steam pipe is 160-200℃; And / or, in step S1, the temperature of the synergistic anaerobic pre-reaction tank is 42-60℃, or the temperature of the synergistic anaerobic pre-reaction tank is 58-90℃; And / or, the temperature of the synergistic anaerobic pre-reaction tank is greater than the temperature of the first anaerobic digester; And / or, in step S2, the temperature of the first anaerobic digester is 30-60℃; And / or, in step S2, the temperature of the second anaerobic digester is 30-60℃; And / or, in step S4, the heating and drying method is indirect heat exchange.

3. The method for co-treatment of sludge and organic waste as described in claim 2, characterized in that, In step S2, the temperature of the first anaerobic digester is 32-38℃, or the temperature of the first anaerobic digester is 52-58℃. And / or, in step S2, the temperature of the second anaerobic digester is 32-38°C, or the temperature of the second anaerobic digester is 52-58°C.

4. The method for co-treatment of sludge and organic waste as described in claim 3, characterized in that, When the temperature range of both the first anaerobic digester and the second anaerobic digester is 52-58℃, the digestion time of the slurry material is 15 days or more. Alternatively, when the temperature range of the first anaerobic digester and the second anaerobic digester is 32-38°C, the digestion time of the liquefied material is 20 days or more.

5. The method for co-treatment of sludge and organic waste as described in claim 1, characterized in that, In step S1, the organic matter content of the raw material is 60% or more; And / or, the sludge includes municipal sludge; And / or, the organic waste includes one or more of the following: kitchen waste, industrial organic waste, agricultural organic waste, aquatic plants, and livestock and poultry manure; And / or, the cyclic pretreatment includes one or more of grinding, microwave treatment and ultrasonic treatment.

6. The method for co-treatment of sludge and organic waste as described in claim 1, characterized in that, In step S1, the raw materials also include industrial water and / or pharmaceuticals; And / or, in the synergistic anaerobic pre-reaction tank, the residence time of the raw materials is 12-24 h; And / or, the proportion of raw materials that have undergone cyclic pretreatment is 10-100 wt%, and the percentage is the ratio of the mass of the material that has undergone cyclic pretreatment to the total mass of the raw materials.

7. The method for co-treatment of sludge and organic waste as described in claim 6, characterized in that, The reagents include oxidizing agents and / or alkaline agents.

8. The method for co-treatment of sludge and organic waste as described in claim 7, characterized in that, The reagent includes one or more of iron salts, hydrogen peroxide, and ozone solution.

9. The method for co-treatment of sludge and organic waste as described in claim 1, characterized in that, In step S2, the solids content of the liquefied material does not exceed 12%; And / or, in step S2, the pH value of the first anaerobic digester is 6.5-7.5; And / or, in step S2, the pH value of the second anaerobic digester is 6.5-7.5; And / or, in step S2, the temperature difference within the first anaerobic digester does not exceed 3°C; And / or, in step S2, the temperature difference within the second anaerobic digester does not exceed 5°C; And / or, in step S2, the biogas is purified in the biogas storage and purification unit and then stored, and the residual gas produced enters the residual gas combustion tower. And / or, in step S3, the biogas is fed from the biogas storage and purification unit into the steam boiler for combustion; And / or, in step S4, before the heating and drying, the digestate is dehydrated to obtain digested sludge; And / or, in step S4, the moisture content of the dried sludge is less than 25%, and the solid content is 75% or more.

10. The method for co-treatment of sludge and organic waste as described in claim 9, characterized in that, In step S2, the solids content of the liquefied slurry is 10-12%. And / or, in step S4, the moisture content of the digested sludge is 80% or less.

11. The method for co-treatment of sludge and organic waste as described in claim 9, characterized in that, In step S2, after purification, the methane content in the biogas is 75% or higher; And / or, in step S2, after purification treatment, the hydrogen sulfide content in the biogas is less than 20 mg / Nm³. 3 .

12. The method for co-treatment of sludge and organic waste as described in claim 1, characterized in that, The synergistic anaerobic pre-reaction tank also includes an industrial water inlet and / or a compound reagent inlet; And / or, the drying treatment unit further includes a sludge dewatering device and a dewatered sludge silo, and the second anaerobic digester is connected in sequence to the sludge dewatering device, the dewatered sludge silo and the sludge drying equipment; And / or, the sludge and organic waste co-treatment system further includes a biogas storage and purification unit, the inlet of which is connected to the gas phase outlet of the first anaerobic digester and the gas phase outlet of the second anaerobic digester, respectively, for storing and purifying the biogas generated after anaerobic digestion; the fuel gas outlet of the biogas storage and purification unit is connected to the steam boiler.

13. The method for co-treatment of sludge and organic waste as described in claim 12, characterized in that, The liquid phase outlet of the sludge dewatering device is equipped with a drain outlet; And / or, the exhaust outlet of the biogas storage and purification unit is also connected to a residual gas combustion tower, which is provided with an exhaust port.

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