System for preparing carbon source from biomass hydrothermal filtrate and sludge circulation reduction system

Abstract

The invention relates to the technical field of biomass waste treatment, and discloses a system for preparing a carbon source from biomass hydrothermal filtrate and a sludge circulation reduction system. In the system for preparing the carbon source from the biomass hydrothermal filtrate, a biochemical unit is used for biochemically treating sludge water, and the sludge water is generated by sludge / sewage pretreatment; the solid-liquid separation unit is connected with the biochemical unit and is used for performing solid-liquid separation on the sludge water to generate sludge; the anaerobic tank is connected with the solid-liquid separation unit and is used for decomposing organic matters in the sludge; the homogenizing tank is connected with the anaerobic tank and is used for homogenizing the sludge; the hydrothermal reactor is connected with the homogenizing tank and is used for hydrothermal decomposition of organic matters in the sludge; and the flash evaporator is connected with the hydrothermal reactor and is used for concentrating a hydrothermal decomposition product of the hydrothermal reactor. According to the technical scheme, the organic matters are subjected to biochemical treatment and secondary treatment of hydrothermal decomposition, so that the organic matters are degraded more thoroughly and effectively. In addition, biomass waste can be treated to obtain a carbon source product, and recycling of the waste is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass waste treatment, and particularly to a system for preparing carbon source from biomass hydrothermal filtrate and a sludge recycling and reduction system. Background Art

[0002] With the development of urban economy and the improvement of people's living standards, the discharge of urban domestic sewage has increased significantly, and the eutrophication of water quality has become increasingly serious. In view of this, for the purpose of protecting the natural environment, the wastewater discharge standards are gradually increasing. However, in municipal sewage treatment or the treatment of leachate from urban landfills, there are problems of imbalance in carbon-nitrogen ratio and insufficient carbon source. To meet the discharge standard of total nitrogen in the effluent, it is necessary to add carbon source. Currently, the commonly used carbon sources in water treatment projects are: (1) traditional carbon sources, including liquid organic substances such as methanol, ethanol, acetic acid and sugars; (2) other types of carbon sources, such as industrial wastewater and landfill leachate.

[0003] During the operation and maintenance of urban life and urban municipal facilities related to urban life activities, a large amount of sludge is generated. According to the source, it can be divided into sewage treatment plant sludge, water supply plant sludge, drainage pipeline sludge, dredged sludge and construction mud, etc. Among them, sludge, as the solid product of urban sewage treatment, contains a large amount of organic matter, mainly composed of carbon (mass ratio is about 58%, calculated on a dry basis); the organic matter is mainly carbohydrates, proteins and fats; it also contains a large number of microorganisms, such as bacteria, actinomycetes, viruses, parasites, protozoa, rotifers and fungi, etc. At present, in sludge treatment, the water holding capacity of sludge is strong, and a large amount of energy is consumed during the processes of dewatering and drying the sludge for reduction. The final product often causes secondary pollution due to insufficient reduction and incomplete stabilization, and it is difficult to carry out effective resource utilization. In addition, in current sludge treatment, the carbon source generated during the treatment is not fully utilized, and the resource utilization is not thorough enough. Summary of the Invention

[0004] The present invention provides a system for preparing carbon source from biomass hydrothermal filtrate and a sludge recycling and reduction system to solve the above technical problems in the prior art that the resource utilization of urban sludge is not thorough and comprehensive enough.

[0005] According to a first aspect of the present invention, an embodiment provides a system for preparing carbon source from biomass hydrothermal filtrate, including:

[0006] A biochemical unit for biochemically treating sludge water, where the sludge water is generated by sludge / sewage pretreatment;

[0007] A solid-liquid separation unit connected to the biochemical unit and used for solid-liquid separation of the sludge water to generate sludge;

[0008] An anaerobic pond connected to the solid-liquid separation unit and used for decomposing the organic matter in the sludge;

[0009] A homogenization tank, connected to the anaerobic tank and used for homogenizing sludge;

[0010] A hydrothermal reactor, connected to the homogenization tank and used for hydrothermal decomposition of organic matter in sludge; and

[0011] A flash evaporator, connected to the hydrothermal reactor and used for concentrating the hydrothermal decomposition products of the hydrothermal reactor.

[0012] Preferably, the biochemical unit includes: an anoxic biochemical tank and an aerobic biochemical tank, and / or the solid-liquid separation unit includes: a sludge sedimentation tank and a sludge thickening tank;

[0013] Wherein,

[0014] The anoxic biochemical tank is used for treating sludge water by aerobic and facultative aerobic microorganisms under anoxic conditions;

[0015] The aerobic biochemical tank is used for treating sludge water by aerobic microorganisms under oxygen-rich conditions;

[0016] The sludge sedimentation tank is connected to the aerobic biochemical tank and used for gravity sedimentation of suspended solid particles in the sludge water;

[0017] The sludge thickening tank is connected to the sludge sedimentation tank and used for reducing the volume and concentrating the sludge.

[0018] Preferably, the system for preparing carbon source from the hydrothermal filtrate of biomass includes:

[0019] A sludge water reflux branch, used for conveying the sludge water treated by the aerobic biochemical tank into the anoxic biochemical tank for denitrification; and / or

[0020] A sludge reflux branch, used for conveying the sludge treated by the aerobic biochemical tank into the anoxic biochemical tank for denitrification; and / or

[0021] A supernatant reflux branch, used for conveying the supernatant in the sludge thickening tank into the anoxic biochemical tank for denitrification; and / or

[0022] A steam reflux branch, used for recovering the steam generated by the flash evaporator and reusing it; and / or

[0023] A carbon source reflux branch, used for recovering the carbon source to the anoxic biochemical tank to supply the carbon source required for the reaction.

[0024] Preferably, in the sludge water reflux branch, the outlet of the aerobic biochemical tank is connected to the anoxic biochemical tank through a first reflux pipe;

[0025] In the sludge reflux branch, the bottom of the sludge sedimentation tank is connected to the anoxic biochemical tank through a second reflux pipe;

[0026] In the supernatant reflux branch, the upper middle part of the sludge thickening tank is connected to the anoxic biochemical tank through a third reflux pipe;

[0027] In the steam reflux branch, a steam reflux pipe is connected to the flash evaporator, and the steam reflux pipe drains steam to the homogenization tank to heat the material;

[0028] In the carbon source reflux branch, the anoxic biochemical tank is connected to a carbon source reflux pipe, and the carbon source reflux pipe is used to transport the hydrothermal decomposition product and / or the filtrate of the hydrothermal decomposition product to the anoxic biochemical tank.

[0029] Preferably, a plurality of anaerobic tanks are provided, and the plurality of anaerobic tanks are connected in parallel.

[0030] Preferably, the system for preparing carbon source from biomass hydrothermal filtrate includes:

[0031] A solid-liquid separation device, connected to the flash evaporator; the solid-liquid separation device is used to separate the solid and liquid in the hydrothermal decomposition product.

[0032] According to the second aspect of the present invention, an embodiment provides a method for preparing carbon source from biomass hydrothermal filtrate, including the following steps:

[0033] S1. Biochemical treatment of sludge water, where the sludge water is produced by pretreatment of sludge / sewage;

[0034] S2. Solid-liquid separation of the sludge water to produce sludge;

[0035] S3. Anaerobic microorganisms in the anaerobic tank decompose the organic matter in the sludge to produce biogas;

[0036] S4. Homogenization treatment of the sludge biologically treated by the anaerobic tank;

[0037] S5. Hydrothermal decomposition of the organic matter in the sludge under high temperature and high pressure;

[0038] S6. Cooling and depressurizing the hydrothermal decomposition product to obtain a carbon source product.

[0039] Preferably, the method for preparing carbon source from biomass hydrothermal filtrate further includes the following steps:

[0040] S11. Sludge water reflux, where the sludge water treated by the aerobic biochemical tank is transported into the anoxic biochemical tank for denitrification. In the biochemical treatment of the sludge water, the anoxic biochemical tank treats the sludge water by aerobic and facultative aerobic microorganisms under anoxic conditions, and the aerobic biochemical tank treats the sludge water by aerobic microorganisms under oxygen-rich conditions; and / or

[0041] S12. Sludge reflux, wherein the sludge treated in the aerobic bioreactor is transported into the anoxic bioreactor for denitrification. In the biochemical treatment of the sludge water, in the anoxic bioreactor, aerobic and facultative anaerobic microorganisms treat the sludge water under anoxic conditions, and in the aerobic bioreactor, aerobic microorganisms treat the sludge water under oxygen-rich conditions; and / or

[0042] S13. Supernatant reflux, wherein the supernatant in the solid-liquid separation unit is transported into the anoxic bioreactor for denitrification, and the solid-liquid separation unit separates the sludge water to produce sludge; and / or

[0043] S14. Steam reflux, wherein the steam generated by the flash evaporator is recovered and reused, and the flash evaporator concentrates the hydrothermal decomposition products; and / or

[0044] S15. Carbon source reflux, wherein the carbon source from the hydrothermal decomposition products is recovered and supplied to the anoxic bioreactor to provide the carbon source required for the reaction.

[0045] Preferably, the method for preparing a carbon source from the biomass hydrothermal filtrate further includes the following steps:

[0046] S7. Solid-liquid separation of the hydrothermal decomposition products to obtain a carbon source filtrate.

[0047] According to the third aspect of the present invention, an embodiment provides a sludge recycling and reduction system, including:

[0048] The system for preparing a carbon source from the biomass hydrothermal filtrate as described in any one of the above; and

[0049] A pretreatment unit for pretreating sludge / sewage to separate impurities.

[0050] The technical solution of the present invention can safely treat and degrade the organic matter in the biomass waste without causing secondary pollution to the surrounding environment. Among them, the organic matter is biochemically treated and then secondarily treated by hydrothermal decomposition, and the degradation of the organic matter is more thorough and effective. In addition, the biomass waste will obtain carbon source products after anaerobic treatment and hydrothermal decomposition treatment, and the carbon source products have high economic value; it not only solves the environmental pollution problem of the biomass waste, but also realizes the recycling of the waste and creates more value. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is a schematic structural diagram of a system for preparing a carbon source from biomass hydrothermal filtrate in an embodiment;

[0052] Figure 2 is another schematic structural diagram of a system for preparing a carbon source from biomass hydrothermal filtrate in an embodiment;

[0053] Figure 3 is a schematic structural diagram of a sludge recycling and reduction system in an embodiment;

[0054] Figure 4 It is a schematic structural diagram of a pretreatment unit in an embodiment;

[0055] Figure 5 It is a schematic structural diagram of an impurity removal tank in an embodiment.

[0056] Reference numerals:

[0057] 11 - steel frame; 12 - chain plate; 13 - lifting plate; 14 - impurity removal cylinder; 15 - impurity outlet; 16 - screen plate; 17 - sand outlet; 18 - conical shell; 19 - air flotation mechanism; 20 - baffle; 21 - chain plate conveyor. Detailed implementation manners

[0058] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0059] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0060] It should be noted that the terms "first", "second", etc. in the present invention are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances, so as to describe the embodiments of the present invention here. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0061] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element can be directly on the other element, or there may also be an intermediate element. Moreover, in the present invention, when it is described that an element is "connected" to another element, the element can be "directly connected" to the other element, or "connected" to the other element through a third element.

[0062] Embodiment 1

[0063] As Figures 1-3, this embodiment provides a system for preparing carbon source from biomass hydrothermal filtrate, which includes a biochemical unit, a solid-liquid separation unit, an anaerobic pond, a homogenization tank, a hydrothermal reactor, and a flash evaporator connected in sequence. Among them, the biochemical unit is used for biochemical treatment of sludge water, and the sludge water is generated by sludge / sewage pretreatment. Here, the sludge water can be understood as sewage containing sludge. The solid-liquid separation unit is used for solid-liquid separation of the sludge water to produce sludge, thus realizing the main function of separating sludge from sewage. The anaerobic pond is used to decompose the organic matter in the sludge and produce biogas (i.e., generate marsh gas). A stirring mechanism can be set in the homogenization tank, and the operation of the stirring mechanism can play the role of stirring and crushing the materials; the homogenization tank is used to homogenize the sludge water and sludge after anaerobic biological treatment. Here, homogenization refers to the process of breaking the solid particles in the liquid material, making the solid particles achieve ultra-fine refinement, and forming a uniform suspension emulsion; homogenization treatment is beneficial to improving the dispersion of useful media in the dispersion medium. The hydrothermal reactor is connected to the homogenization tank and receives the well-homogenized sludge. The hydrothermal reactor is used for hydrothermal decomposition of the organic matter in the sludge; among them, the sludge water and sludge have undergone aerobic and anaerobic biological treatments, and the organic matter has been degraded to a certain extent. At this time, the organic matter enters the hydrothermal reactor again to undergo hydrolysis to form a cyclic organic matter degradation treatment, and the cyclic treatment is more thorough, and the organic matter removal is more thorough and comprehensive. Finally, the flash evaporator is connected to the hydrothermal reactor to concentrate the hydrothermal decomposition products; among them, the hydrothermal decomposition products discharged from the hydrothermal reactor are cooled and depressurized in the flash evaporator, and the water is separated from the hydrothermal decomposition products in the form of steam through flashing.

[0064] In one embodiment, the biochemical unit includes: an anoxic biochemical pond and an aerobic biochemical pond; the sludge water first passes through the anoxic biochemical pond and then through the aerobic biochemical pond. The anoxic biochemical pond is used for treating the sludge water by aerobic and facultative aerobic microorganisms under anoxic conditions; the aerobic biochemical pond is used for treating the sludge water by aerobic microorganisms under oxygen-rich conditions. Denitrification reaction occurs in the anoxic biochemical pond. In the aerobic biological treatment of the aerobic biochemical pond, aerobic microorganisms are used to carry out biological metabolism in the presence of oxygen to degrade organic matter and achieve harmless treatment. Microorganisms use the organic matter existing in the water as a substrate for aerobic metabolism. Through a series of biochemical reactions, energy is released step by step, and finally it stabilizes as low-energy inorganic substances, meeting the harmless requirements so as to return to the natural environment or be further treated. Denitrification reaction occurs in the anoxic biochemical pond, and macromolecular organic matter is degraded into small-molecular organic matter, improving the subsequent aerobic treatment ability.

[0065] In one embodiment, the solid-liquid separation unit includes a sludge sedimentation tank and a sludge thickening tank; the sludge sedimentation tank is connected to the aerobic bioreactor and is used for gravity sedimentation of suspended solid particles in the sludge water; the sludge thickening tank is connected to the sludge sedimentation tank and is used for sludge volume reduction and concentration improvement. The sludge thickening tank can reduce the moisture content of the sludge, reduce the sludge volume, and at the same time has the core function of increasing the sludge concentration. The sludge thickening tank is connected to the sludge sedimentation tank and receives the sludge precipitated in the sludge sedimentation tank; the effluent of the sludge sedimentation tank is filtered and then treated by the disinfection unit and discharged outward; among them, membrane filtration technology can be used for the filtration operation, and a semi-permeable membrane is used to separate pollutants, including processes such as ultrafiltration, nanofiltration, and reverse osmosis; physical disinfection can be used for disinfection, such as in ultraviolet disinfection, where ultraviolet rays damage the DNA of microorganisms without the need for chemical agents. The sludge treated by the anaerobic tank is supplied by the sludge thickening tank; in the anaerobic biological treatment of the anaerobic tank, anaerobic bacteria hydrolyze and acidify macromolecular organic matter, suspended solids, soluble organic matter, etc. in it, and the macromolecular organic matter is degraded into small-molecular organic matter. Nitrification reaction occurs in the aerobic bioreactor. Due to the full utilization of denitrifying bacteria in the previous anoxic bioreactor, the organic load of the aerobic bioreactor and the anaerobic tank is reduced; the aerobic bioreactor can further degrade the organic matter that was not degraded in the anoxic section and improve the removal efficiency of the organic matter.

[0066] In one embodiment, a filtration unit is provided and connected to the sludge sedimentation tank. During the filtration operation of the effluent of the sedimentation tank, waste liquid will be generated, and the waste liquid is refluxed to the homogenization tank to supplement the water required for homogenization, and then the hydrothermal reaction is carried out.

[0067] In one embodiment, biogas is generated during the anaerobic reaction of the anaerobic tank, and the biogas can be collected and used. Preferably, the biogas can be sent to a boiler for combustion to generate steam, and the steam is supplied to the homogenization tank and the hydrothermal reactor to provide heat sources (detailed below). Preferably, the anaerobic tanks are arranged in a parallel form. Since the speed of aerobic biological treatment / biochemical unit is fast and the speed of anaerobic biological treatment is slow, more anaerobic tanks are designed for use. Of course, the above only describes the cooperation form between the anaerobic tank and the aerobic bioreactor, and does not limit the quantity.

[0068] In one embodiment, an aeration mechanism is arranged in the aerobic bioreactor, and air is introduced into the aerobic bioreactor through the aeration mechanism. Among them, when over-aerated, it is easy to cause sludge aging, and the sludge becomes grayish-white; a flow meter can be set to control the air volume and the ventilation rate.

[0069] In one embodiment, the system for preparing carbon source from biomass hydrothermal filtrate further includes: a sludge water reflux branch, and the sludge water reflux branch is used to transport the sludge water treated by the aerobic bioreactor into the anoxic bioreactor, and the nitrified liquid enters the anoxic bioreactor for denitrification. In the sludge water reflux branch, the outlet of the aerobic bioreactor is connected to the anoxic bioreactor through a first reflux pipe.

[0070] In one embodiment, the system for preparing carbon source from biomass hydrothermal filtrate further includes: a sludge reflux branch, which is used to transport the sludge treated in the aerobic bioreactor into the anoxic bioreactor for denitrification, and a mixed flora system can be formed. In the sludge reflux branch, the bottom of the sludge sedimentation tank is connected to the anoxic bioreactor through a second reflux pipe.

[0071] In one embodiment, the system for preparing carbon source from biomass hydrothermal filtrate further includes: a supernatant reflux branch, which is used to transport the supernatant in the sludge thickening tank into the anoxic bioreactor for denitrification; wherein, a part of the nitrified liquid enters the anoxic bioreactor for denitrification. In the supernatant reflux branch, the upper middle part of the sludge thickening tank is connected to the anoxic bioreactor through a third reflux pipe.

[0072] In one embodiment, the system for preparing carbon source from biomass hydrothermal filtrate further includes: a steam reflux branch, which is used to recover the steam generated by the flash evaporator and reuse it. In the steam reflux branch, a steam reflux pipe is connected to the flash evaporator, and the steam reflux pipe drains the steam to the homogenizing tank to heat the material, realizing the secondary utilization of waste heat. Of course, the steam reflux pipe can also drain the steam to the anaerobic tank to heat the material, and the secondary utilization of waste heat can also be realized. In addition, for the heating of the aerobic bioreactor and the anoxic bioreactor, coils are placed in the aerobic bioreactor and the anoxic bioreactor, and the steam generated by the flash evaporator is drained to flow through the coils to heat the sludge water or sludge around the coils. Of course, the homogenizing tank and the anaerobic tank can be provided with coils, and the steam overflows from the coils to directly heat the material; the homogenizing tank and the anaerobic tank can also be set as jacket structures, and the steam is introduced into the jacket to indirectly heat the material through heat exchange. Preferably, the temperature of the aerobic bioreactor is controlled at 5 - 35 °C, and the nitrification reaction rate can be better guaranteed. Further preferably, the temperature of the aerobic bioreactor is controlled at 30 - 35 °C, and the nitrification reaction rate is better. Preferably, the temperature of the anoxic bioreactor is controlled at 5 - 27 °C, and the denitrification reaction rate can be better guaranteed and the phosphorus removal effect is better. Further preferably, the temperature of the anoxic bioreactor is controlled at 15 - 25 °C, and the nitrification reaction rate is better.

[0073] In one embodiment, hydrothermal waste gas is generated in the hydrothermal reactor. The hydrothermal waste gas is directly guided back and discharged into the anaerobic pond for heating and raising the temperature of the anaerobic pond. The hydrothermal non-condensable gas is discharged into the boiler together with the biogas generated in the anaerobic pond, and the hydrothermal non-condensable gas can be co-incinerated with the biogas. The steam generated by the boiler can be introduced into the hydrothermal reactor to heat the material, promoting the sludge hydrothermal reaction, thereby realizing the recycling of hydrothermal waste gas and steam. Among them, in order to simplify the process, the hydrothermal waste gas (hydrothermal non-condensable gas) can also be directly discharged into the boiler to co-incinerate with the fuel (the fuel can be biogas or natural gas from the gas source, etc.) to generate steam, and the steam can be supplied to the hydrothermal reactor to heat the material. In addition, if energy conservation is considered, the heat generated by cooling the hydrothermal sludge (such as the hot water generated by heat exchange in the cooler) can be transferred to the material in the anaerobic reactor.

[0074] In one embodiment, the system for preparing carbon source from biomass hydrothermal filtrate further includes: a carbon source reflux branch, and the carbon source reflux branch is used to recover the carbon source to the anoxic biochemical pond to supply the carbon source required for the reaction. In the carbon source reflux branch, the anoxic biochemical pond is connected to a carbon source reflux pipe, and the carbon source reflux pipe is used to transport the filtrate containing hydrothermal decomposition products and / or hydrothermal decomposition products to the anoxic biochemical pond.

[0075] In one embodiment, the hydrothermal decomposition product is passed through a cooler to reduce the temperature. After that, the cooled hydrothermal decomposition product is continuously transported into a solid-liquid separation device (such as a filter press (preferably a plate and frame filter press)) for solid-liquid separation, and the obtained filtrate contains a carbon source. Further, the filtrate can be filtered, concentrated, and reagents can be added to obtain a carbon source product. Optionally, the filtrate containing the carbon source or the carbon source product is refluxed to the anoxic biochemical tank through the carbon source reflux branch for denitrification. The carbon source reflux branch has been described above. In one embodiment, the filtrate containing the carbon source is subjected to ammonia and nitrogen removal treatment to increase the carbon-nitrogen ratio of the filtrate. NaOH is added to the filtrate to adjust the pH to alkaline; in actual operation, the pH value of the solution needs to be adjusted according to the working conditions to increase the proportion of free ammonia, so as to enhance the effect of aeration ammonia and nitrogen removal. After that, the filtrate is discharged into a buffer tank, and aeration treatment is directly carried out in the buffer tank under high temperature conditions (an aeration mechanism is provided in the buffer tank) to remove ammonia and nitrogen in the filtrate, and part of the COD is lost during aeration; at this time, the outlet temperature of the cooler should be controlled to ensure that the filtrate has a temperature suitable for the process conditions when it is discharged into the buffer tank, or the cooler can be directly omitted to make full use of the heat carried by the material itself. As mentioned above, the pH value has an important influence on the morphological distribution of ammonia and nitrogen. Under high temperature conditions, free ammonia (NH3) is more active and is easy to escape from water; it can be seen that under high temperature and alkaline conditions, the proportion of free ammonia increases, which is more conducive to aeration ammonia and nitrogen removal. Finally, the ammonia and nitrogen removed filtrate is filtered to remove impurities and then discharged into an ultrafiltration system for concentration. The COD, ammonia and nitrogen concentration, and total nitrogen concentration of the concentrated filtrate are greatly increased, and a carbon source product with a high carbon-nitrogen ratio can be obtained. The clear liquid produced by the ultrafiltration system can be treated and discharged; among them, filtering first and then concentrating can prevent membrane pollution and blockage to protect the nanofiltration system, and at the same time can improve the concentration efficiency and purity. The concentrated filtrate can also be refluxed and concentrated again to further improve the concentration degree of the filtrate. The concentrated filtrate is refluxed to the anoxic biochemical tank through the carbon source reflux branch for denitrification; so that the system for preparing carbon source from the biomass hydrothermal filtrate of the present invention basically does not need to add additional carbon source, and the organic matter in the original sludge can be fully utilized as a carbon source for denitrification, and at the same time the purpose of biodegradation can be achieved.

[0076] The system for preparing carbon source from the biomass hydrothermal filtrate of the present invention can first pass the organic matter in the biomass waste through an aerobic biochemical tank, an anoxic biochemical tank, and an anaerobic tank, and through alternating aerobic and anoxic treatments, and then perform hydrothermal decomposition treatment on the undegraded or insufficiently degraded organic matter. After the organic matter is subjected to multiple degradation treatments, the reduction of the biomass waste is more thorough and effective. In addition, the biomass waste can also be regarded as a resource. Through aerobic treatment, anoxic treatment, and hydrothermal decomposition treatment, the decomposition product carbon source is resourcefully utilized, and the carbon source can be recycled to the anoxic biochemical tank for secondary use to promote the efficiency of biological treatment; it not only solves the environmental pollution problem of biomass waste, but also realizes the recycling of waste.

[0077] Example Two

[0078] This embodiment provides a method for preparing a carbon source from biomass hydrothermal filtrate, comprising the following steps:

[0079] S1. Biochemical treatment of sludge water, where the sludge water is produced by sludge / sewage pretreatment;

[0080] S2. Solid-liquid separation of the sludge water to produce sludge;

[0081] S3. Anaerobic microorganisms in the anaerobic tank decompose the organic matter in the sludge to produce biogas;

[0082] S4. Homogenization treatment of the sludge biologically treated in the anaerobic tank;

[0083] S5. Hydrothermal decomposition of the organic matter in the sludge under high temperature and high pressure;

[0084] S6. Cooling and depressurizing the hydrothermal decomposition product to obtain a carbon source product;

[0085] S7. Solid-liquid separation of the hydrothermal decomposition product to obtain a carbon source filtrate.

[0086] In one embodiment, the method for preparing a carbon source from biomass hydrothermal filtrate further comprises the following steps:

[0087] S11. Sludge water reflux, where the sludge water treated by the aerobic biochemical tank is transported into the anoxic biochemical tank for denitrification, enabling the nitrified liquid to enter the anoxic biochemical tank for denitrification; in the biochemical treatment of sludge water, in the anoxic biochemical tank, aerobic and facultative anaerobic microorganisms treat the sludge water under anoxic conditions, and in the aerobic biochemical tank, aerobic microorganisms treat the sludge water under oxygen-rich conditions.

[0088] In one embodiment, the method for preparing a carbon source from biomass hydrothermal filtrate further comprises the following steps:

[0089] S12. Sludge reflux, where the sludge treated by the aerobic biochemical tank is transported into the anoxic biochemical tank for denitrification, which can form a mixed microbial population system; in the biochemical treatment of sludge water, in the anoxic biochemical tank, aerobic and facultative anaerobic microorganisms treat the sludge water under anoxic conditions, and in the aerobic biochemical tank, aerobic microorganisms treat the sludge water under oxygen-rich conditions. Among them, the mixed microbial population alternates between anoxic and aerobic states and conditions of high and low organic matter concentrations, which is beneficial to improving the sedimentation performance of the sludge and controlling sludge bulking.

[0090] In one embodiment, the method for preparing a carbon source from biomass hydrothermal filtrate further comprises the following steps:

[0091] S13. Return the supernatant. Among them, the supernatant in the solid-liquid separation unit is transported into the anoxic biochemical pool for denitrification. Among them, a part of the nitrified liquid enters the anoxic biochemical pool for denitrification. The solid-liquid separation unit separates the sludge from the water to produce sludge.

[0092] In one embodiment, the method for preparing a carbon source from the hydrothermal filtrate of biomass further includes the following steps:

[0093] S14. Return the steam. Among them, the steam generated by the flash evaporator is recovered and reused. The flash evaporator concentrates the hydrothermal decomposition products. The steam is returned to the anaerobic pool and / or the homogenization tank to heat the materials, realizing the secondary utilization of waste heat.

[0094] In one embodiment, the method for preparing a carbon source from the hydrothermal filtrate of biomass further includes the following steps:

[0095] S15. Carbon source reflux, wherein the carbon source from the hydrothermal decomposition product is recovered and supplied to the anoxic biochemical pool for the carbon source required for the reaction. The anoxic biochemical pool is connected to a carbon source reflux pipe, and the carbon source reflux pipe is used to transport the filtrate containing the hydrothermal decomposition product and / or the hydrothermal decomposition product to the anoxic biochemical pool. In one embodiment, the hydrothermal decomposition product is fed into a solid-liquid separation device (such as a filter press (preferably a plate and frame filter press)) for solid-liquid separation, and the obtained filtrate contains a carbon source. Further, the filtrate can be filtered, concentrated, and reagents can be added to obtain a carbon source product. Optionally, the filtrate containing the carbon source or the carbon source product is refluxed to the anoxic biochemical pool through a carbon source reflux branch for denitrification. The carbon source reflux branch has been described above. In one embodiment, the filtrate containing the carbon source is subjected to deammonification and denitrification treatment to increase the carbon-nitrogen ratio of the filtrate. NaOH is added to the filtrate to adjust the pH to alkaline; in actual operation, the pH value of the solution needs to be adjusted according to the working conditions to increase the proportion of free ammonia, thereby enhancing the effect of aeration deammonification. Then, the filtrate is discharged into a buffer tank and directly aerated in the buffer tank under high-temperature conditions (an aeration mechanism is provided in the buffer tank) to remove ammonia nitrogen in the filtrate, and part of the COD is lost during aeration; among them, the heat carried by the material itself is fully utilized to provide a high-temperature environment required for aeration treatment, saving energy. As mentioned above, the pH value has an important influence on the morphological distribution of ammonia nitrogen. Under high-temperature conditions, free ammonia (NH3) is more active and is easy to escape from water; it can be seen that under high-temperature and alkaline conditions, the proportion of free ammonia increases, which is more conducive to aeration deammonification. Finally, the deammonified and denitrified filtrate is filtered to remove impurities and then discharged into an ultrafiltration system for concentration. The COD, ammonia nitrogen concentration, and total nitrogen concentration of the concentrated filtrate are greatly increased, and a carbon source product with a high carbon-nitrogen ratio can be obtained. The clear liquid produced by the ultrafiltration system can be treated and discharged; among them, filtering first and then concentrating can prevent membrane pollution and blockage to protect the nanofiltration system, and at the same time can improve the concentration efficiency and purity. The concentrated filtrate can also be refluxed and concentrated again to further improve the concentration degree of the filtrate. The concentrated filtrate is refluxed to the anoxic biochemical pool through a carbon source reflux branch for denitrification; so that the system for preparing carbon source from the hydrothermal filtrate of this biomass basically does not need to add additional carbon source, and the organic matter in the original sludge can be fully utilized as a carbon source for denitrification, and at the same time the purpose of biodegradation can be achieved.

[0096] In one embodiment, hydrothermal waste gas is generated in the hydrothermal reactor. The hydrothermal waste gas is directly guided and refluxed into the anaerobic pond for heating and warming the anaerobic pond. The hydrothermal non-condensable gas is discharged into the boiler together with the biogas generated by the anaerobic pond, and the hydrothermal non-condensable gas can be co-incinerated with the biogas. The steam generated by the boiler can be introduced into the hydrothermal reactor to heat the material, promoting the sludge hydrothermal reaction, so as to realize the recycling of hydrothermal waste gas and steam. Among them, in order to simplify the process, the hydrothermal waste gas (hydrothermal non-condensable gas) can also be directly discharged into the boiler to co-incinerate with the fuel (the fuel can be biogas or natural gas from the gas source, etc.) to generate steam, and the steam can be supplied to the hydrothermal reactor to heat the material. In addition, if energy conservation is considered, the heat of cooling the hydrothermal sludge (such as the hot water generated by heat exchange in the cooler) can be transferred to the material in the anaerobic reactor.

[0097] The method for preparing carbon source from biomass hydrothermal filtrate of the present invention can safely treat and degrade the organic matter in biomass waste without causing secondary pollution to the surrounding environment. For example, when treating sludge, the organic matter in the sludge, such as proteins, lipids, polysaccharides and humic substances, is first treated alternately under aerobic and anoxic conditions, and then treated by hydrothermal decomposition. The organic matter is degraded more thoroughly and effectively. In addition, biomass waste can also be regarded as a kind of resource. Through aerobic treatment, anoxic treatment and hydrothermal decomposition treatment, the carbon source of the decomposition products is utilized resourcefully, which not only solves the environmental pollution problem of biomass waste, but also realizes the recycling of waste.

[0098] Example Three

[0099] Such as Figures 1-5 , this embodiment provides a sludge circulation reduction system, including: a system for preparing carbon source from biomass hydrothermal filtrate according to any one of the above embodiments, and a pretreatment unit for pretreating sludge / sewage to separate impurities. Among them, a filter press can be used to separate the solid and liquid of the hydrothermal decomposition product.

[0100] In one embodiment, the pretreatment unit includes an impurity removal grid and a grit chamber. Among them, the impurity removal grid is used to separate impurities in the sludge during sludge pretreatment. The impurity removal grid includes a coarse grid and a fine grid. The sludge passes through the coarse grid and the fine grid in sequence to remove impurities in the sludge. Water flushing is used during impurity removal. At this time, the incoming water can be the qualified effluent filtered and disinfected discharged from the sludge sedimentation tank, or the wastewater formed by the waste steam discharged from the homogenization tank and the hydrothermal reactor. The grit chamber can utilize the principle of stable water flow and free sedimentation of particles. By setting a longer tank body and maintaining a lower flow rate, the inorganic particles settle to the bottom of the tank during the water flow. The sand can be transported out for landfill. Preferably, an aeration mechanism is added on the basis of the above horizontal flow grit chamber. By aeration, the deposited sand grains rub against each other to remove the organic matter on their surfaces, improve the concentration of influent organic matter, and clean the sand grains at the same time.

[0101] In one embodiment, the pretreatment unit further includes: a de-impurity tank; the de-impurity tank is connected to the de-impurity grille, and the de-impurity tank is arranged between the de-impurity grille and the sand settling tank; the de-impurity tank is used for secondary de-impurity, and the secondary de-impurity includes flotation impurities, sedimentation impurities and primary sedimentation sand particles.

[0102] In one embodiment, Figure 5 , the debris removal tank includes: a debris removal barrel 14 and a debris catching mechanism. The debris catching mechanism is set as a chain plate conveyor 21; the chain plate conveyor 21 is tilted and fixed in the debris removal barrel 14; the first end of the chain plate conveyor 21 is arranged in the debris removal barrel 14, and the second end extends out of the debris removal barrel 14; a lifting plate 13 is fixed on the chain plate 12 of the chain plate conveyor 21, and the lifting plate 13 is used to lift the impurities floating in the debris removal barrel 14; wherein, a cone shell 18 is provided at the bottom of the debris removal barrel 14, and a sand outlet 17 for discharging sand is provided at the small end of the cone shell 18. Regarding the chain plate conveyor 21, the upper end of the chain plate conveyor 21 is fixed on the steel frame 11, and the driving roller at the upper end is driven by the motor, and the driving roller drives the chain plate 12 to move. The lower end of the chain plate conveyor 21 is placed in the debris removal barrel 14 and fixed, or the passive roller can be directly installed in the debris removal barrel 14. When the chain plate 12 is in motion, the scum enters the working area of the chain plate 12 , and the lifting plate 13 rises along with the chain plate 12 to pick up the scum, thereby achieving the effect of removing impurities.

[0103] In one embodiment, a plurality of baffles 20 are fixedly connected to the outer wall of the debris removal barrel 14, and the height of the plurality of baffles 20 is coordinated with the chain conveyor 21, and they are lowered along the movement trajectory of the chain conveyor 21. The arrangement of the baffles 20 can prevent the salvaged scum from being brought into the debris removal barrel 14 again by the chain conveyor 21 without being cleaned up in time. In order to clean the scum on the lifting plate 13 of the chain conveyor 21, water flushing is adopted to flush the scum out of the debris removal barrel 14. The water used here refers to the water source of the debris removal grid.

[0104] In one embodiment, the impurity removal tank includes: a screen plate 16; the screen plate 16 is fixed in the impurity removal barrel 14; the screen plate 16 is used for sand particles to pass through and receive the sunken impurities in the impurity removal barrel 14; and an impurity outlet 15 is provided on the impurity removal barrel 14 at a position corresponding to the screen plate 16. Among them, a large number of sieve holes are provided on the screen plate 16; of course, the sieve holes can be formed by a screen, and the screen is fixed on a plate frame to form the screen plate 16. Preferably, the screen plate 16 is inclined; and the impurity outlet 15 is provided at the lower end of the screen plate 16. After opening the impurity outlet 15, the impurities piled on the screen plate 16 slide out from the impurity outlet 15. The design of the impurity removal tank can realize the cleaning functions of scum and gravel at the same time, and can separate impurities with a larger specific gravity. Multiple impurity removal processes are integrated in the impurity removal tank to achieve a better impurity removal effect.

[0105] Embodiment 4

[0106] like Figures 1-5, this embodiment provides a sludge recycling and reduction system, in which the system for preparing carbon source from hydrothermal filtrate of biomass is a subsystem of the sludge recycling and reduction system.

[0107] When the sludge / wastewater to be treated (from waterworks, sewage treatment plants, drainage pipes, river dredging, etc.) passes through the grille, large debris such as plastics, cloth, branches, weeds, etc. are filtered out; this is the first filtration and impurity removal of the grille. Then it enters the impurity removal tank to further separate larger debris, flotation impurities, and collect sediment impurities; among them, sand grains will be deposited at the bottom of the impurity removal tank, and after being regularly discharged, they can be recycled for building materials or directly landfilled. Figure 5 As shown in the impurity removal tank, there is a flotation mechanism 19 inside it. Specifically, the flotation mechanism 19 includes a coiled pipe fixed in the impurity removal tank, and air holes are opened on the coiled pipe. After introducing gas (such as compressed air) into the coiled pipe, the gas overflows from the air holes to form bubbles, and the bubbles carry light impurities to float upward and float on the water surface. The floating scum overflows after floating upward and is separated. The floating of the floating scum facilitates it to be promptly fished away by the debris fishing mechanism (among them, the chain conveyor 21 can play the role of fishing debris). Among them, the bubbles generated by the coiled pipe will stir the materials in the impurity removal tank, especially the liquid surface; in this way, the debris on the liquid surface will move violently and float uncertainly, and it is easy to move to the working area of the debris fishing mechanism and be fished away. The sand grains with a larger specific gravity in the impurity removal tank pass through the screen plate 16 and settle to the bottom of the tank, and then are discharged and collected for secondary utilization; stones, porcelain, ironware, etc. with a larger specific gravity accumulate on the inclined screen plate 16, and after being collected to a certain extent, they are discharged outward and then processed. This is the secondary filtration and impurity removal of the impurity removal tank. It can be seen that the design of the impurity removal tank can simultaneously realize the cleaning functions of floating scum and grit, and can separate larger debris with a larger specific gravity. Multiple impurity removal processes are integrated in the impurity removal tank to achieve a better impurity removal effect.

[0108] The above-mentioned sewage that has undergone two separations and impurity removals can also be discharged into the grit chamber for secondary grit removal treatment. Then, the sludge water is discharged into the aerobic biochemical tank for aerobic biochemical treatment, and then into the anoxic biochemical tank for anoxic biochemical treatment. The sludge water after biochemical treatment is transported into the sludge sedimentation tank for sedimentation, and sludge will be generated during sedimentation. It is discharged into the sludge thickening tank for further thickening, and the thickened sludge is discharged into the anaerobic tank for anaerobic biological treatment to improve the ability and degree of biological treatment. The anaerobic tank is used for the secondary biological treatment of sludge. The mixed flora alternates between anoxic and aerobic states and conditions of high and low organic matter concentrations, which is beneficial to improving the sedimentation performance of sludge and controlling sludge bulking. Among them, during the treatment stage of the aerobic biochemical tank - anoxic biochemical tank, sludge reflux, sludge water reflux, and the supernatant reflux to the anoxic biochemical tank to provide nitrifying liquid, forming a microbial cyclic treatment process to accelerate the biochemical treatment efficiency.

[0109] The biologically treated sludge is discharged into a homogenization tank for homogenization treatment. After treatment, the sludge with uniform texture is then transported by a transfer pump into a hydrothermal reactor (where heating equipment can be installed on the hydrothermal reactor). Under high temperature and high pressure conditions, the organic matter in the sludge after aerobic and anoxic biological treatment undergoes hydrolysis; then it enters a flash evaporator with a lower pressure, where flash evaporation occurs; among them, the steam generated by flash evaporation is recycled to the homogenization tank or anaerobic pond to provide a heating environment for them. The flash evaporator can be divided into a series-connected primary flash evaporator and secondary flash evaporator, with the pressure gradually decreasing and the temperature gradually decreasing.

[0110] The hydrothermally treated sludge produces hydrothermal decomposition products, and the hydrothermal decomposition products are passed into a cooler to reduce the temperature. Among them, the waste heat generated can be reused to heat the materials in the anaerobic tank. After that, the hydrothermal decomposition products are subjected to solid-liquid separation, and the obtained filtrate contains a carbon source. Further, the filtrate can be filtered, concentrated, and reagents can be added to prepare a carbon source product. Optionally, the filtrate containing the carbon source or the carbon source product is refluxed to the anoxic biochemistry tank through a carbon source reflux branch for denitrification; among them, in the carbon source reflux branch, the anoxic biochemistry tank receives the hydrothermal decomposition products and / or the filtrate of the hydrothermal decomposition products through a carbon source reflux pipe. In one embodiment, the hydrothermal decomposition products are fed into a solid-liquid separation device (such as a filter press (preferably a plate and frame filter press)) for solid-liquid separation, and the obtained filtrate contains a carbon source. Further, the filtrate can be filtered, concentrated, and reagents can be added to prepare a carbon source product. Optionally, the filtrate containing the carbon source or the carbon source product is refluxed to the anoxic biochemistry tank through a carbon source reflux branch for denitrification. The carbon source reflux branch has been described above. In one embodiment, the filtrate containing the carbon source is subjected to deammoniation and denitrification treatment to increase the carbon-nitrogen ratio of the filtrate. NaOH is added to the filtrate to adjust the pH to alkaline; in actual operation, the pH value of the solution needs to be adjusted according to the working conditions to increase the proportion of free ammonia, so as to enhance the effect of aeration deammoniation and denitrification. After that, the filtrate is discharged into a buffer tank and directly aerated in the buffer tank under high-temperature conditions (an aeration mechanism is provided in the buffer tank) to remove the ammonia nitrogen in the filtrate, and part of the COD is lost during aeration; among them, the heat carried by the material itself is fully utilized to provide the high-temperature environment required for aeration treatment, saving energy. As mentioned above, the pH value has an important influence on the morphological distribution of ammonia nitrogen. Under high-temperature conditions, free ammonia (NH3) is more active and is easy to escape from water; it can be seen that under high-temperature and alkaline conditions, the proportion of free ammonia increases, which is more conducive to aeration deammoniation and denitrification. Finally, the deammoniated and denitrified filtrate is filtered to remove impurities and then discharged into an ultrafiltration system for concentration. The COD, ammonia nitrogen concentration, and total nitrogen concentration of the concentrated filtrate are greatly increased, and a carbon source product with a high carbon-nitrogen ratio can be obtained. The clear liquid produced by the ultrafiltration system can be treated and discharged; among them, filtering first and then concentrating can prevent membrane pollution and blockage to protect the nanofiltration system, and at the same time can improve the concentration efficiency and purity. The concentrated filtrate can also be refluxed and concentrated again to further improve the concentration degree of the filtrate. The concentrated filtrate is refluxed to the anoxic biochemistry tank through a carbon source reflux branch for denitrification; so that the system for preparing a carbon source from the hydrothermal filtrate of this biomass basically does not need to add additional carbon sources, and the organic matter in the original sludge can be fully utilized as a carbon source for denitrification, and at the same time the purpose of biodegradation can be achieved.

[0111] In one embodiment, solid residues are generated during the solid-liquid separation of the hydrothermal decomposition products. After the solid residues are recovered, according to the amount of their nutrient components, they can be landfilled; they can also be made into building materials; they can also be made into fertilizers after fermentation; so as to carry out full resource utilization.

[0112] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A system for preparing a carbon source from biomass hydrothermal filtrate, characterized in that, Comprising: A biochemical unit for biochemically treating sludge water, which is produced by sludge / sewage pretreatment; A solid-liquid separation unit connected to the biochemical unit and used for solid-liquid separation of sludge water to produce sludge; An anaerobic pond connected to the solid-liquid separation unit and used for decomposing organic matter in the sludge; A homogenization tank connected to the anaerobic pond and used for homogenizing the sludge; A hydrothermal reactor connected to the homogenization tank and used for hydrothermal decomposition of organic matter in the sludge; And A flash evaporator connected to the hydrothermal reactor and used for concentrating the hydrothermal decomposition products of the hydrothermal reactor.

2. The system for preparing carbon source from biomass hydrothermal filtrate according to claim 1, wherein, The biochemical unit includes: an anoxic biochemical pond and an aerobic biochemical pond, and / or The solid-liquid separation unit includes: a sludge sedimentation tank and a sludge thickening tank; Wherein, The anoxic biochemical pond is used for treating sludge water by aerobic and facultative aerobic microorganisms under anoxic conditions; The aerobic biochemical pond is used for treating sludge water by aerobic microorganisms under oxygen-rich conditions; The sludge sedimentation tank is connected to the aerobic biochemical pond and used for gravity sedimentation of suspended solid particles in the sludge water; The sludge thickening tank is connected to the sludge sedimentation tank and used for volume reduction and concentration enhancement of the sludge.

3. The system for preparing a carbon source from a biomass hydrothermal filtrate according to claim 2, characterized in that, The system for preparing carbon source from biomass hydrothermal filtrate includes: A sludge water reflux branch for transporting the sludge water treated by the aerobic biochemical pond into the anoxic biochemical pond for denitrification; and / or A sludge reflux branch for transporting the sludge treated by the aerobic biochemical pond into the anoxic biochemical pond for denitrification; and / or A supernatant reflux branch for transporting the supernatant in the sludge thickening tank into the anoxic biochemical pond for denitrification; and / or A steam reflux branch for recovering the steam generated by the flash evaporator and reusing it; and / or A carbon source reflux branch for recovering the carbon source to the anoxic biochemical pond to supply the carbon source required for the reaction.

4. The system for preparing carbon source from biomass hydrothermal filtrate according to claim 3, characterized in that, In the sludge water reflux branch, the outlet of the aerobic biochemical pond is connected to the anoxic biochemical pond through a first reflux pipe; In the sludge reflux branch, the bottom of the sludge sedimentation tank is connected to the anoxic biochemical pond through a second reflux pipe; In the supernatant reflux branch, the middle upper part of the sludge thickening tank is connected to the anoxic biochemical pond through a third reflux pipe; In the steam reflux branch, a steam reflux pipe is connected to the flash evaporator, and the steam reflux pipe drains the steam into the homogenization tank to heat the material; In the carbon source reflux branch, the anoxic biochemical pond is connected to a carbon source reflux pipe, and the carbon source reflux pipe is used for transporting the filtrate containing hydrothermal decomposition products and / or hydrothermal decomposition products to the anoxic biochemical pond.

5. The system for preparing carbon source from biomass hydrothermal filtrate according to claim 1, characterized in that, The anaerobic ponds are provided in multiple numbers, and the multiple anaerobic ponds are connected in parallel.

6. The system for preparing carbon source from biomass hydrothermal filtrate according to any one of claims 1-5, characterized in that, The system for preparing carbon source from biomass hydrothermal filtrate includes: A solid-liquid separation device connected to the flash evaporator; the solid-liquid separation device is used for separating the solid and liquid in the hydrothermal decomposition products.

7. A method for preparing a carbon source from biomass hydrothermal filtrate, characterized in that, Including the following steps: S1. Biochemically treating sludge water, which is produced by sludge / sewage pretreatment; S2. Solid-liquid separating the sludge water and producing sludge; S3. Anaerobic microorganisms in the anaerobic pond decompose the organic matter in the sludge and produce biogas; S4. Homogenizing the sludge biologically treated by the anaerobic pond; S5. Hydrothermally decomposing the organic matter in the sludge under high temperature and high pressure; S6. Cooling and depressurizing the hydrothermal decomposition products to obtain a carbon source product.

8. The method for preparing a carbon source from a biomass hydrothermal filtrate according to claim 7, characterized in that, The method for preparing carbon source from biomass hydrothermal filtrate further includes the following steps: S11. Sludge water reflux, wherein the sludge water treated by the aerobic biochemical tank is transported into the anoxic biochemical tank for denitrification. In the biochemical treatment sludge water, the anoxic biochemical tank treats the sludge water with aerobic and facultative aerobic microorganisms under anoxic conditions, and the aerobic biochemical tank treats the sludge water with aerobic microorganisms under oxygen-rich conditions; and / or S12. Sludge reflux, wherein the sludge treated by the aerobic biochemical tank is transported into the anoxic biochemical tank for denitrification. In the biochemical treatment sludge water, the anoxic biochemical tank treats the sludge water with aerobic and facultative aerobic microorganisms under anoxic conditions, and the aerobic biochemical tank treats the sludge water with aerobic microorganisms under oxygen-rich conditions; and / or S13. Supernatant reflux, wherein the supernatant in the solid-liquid separation unit is transported into the anoxic biochemical tank for denitrification, and the solid-liquid separation unit separates the sludge water to produce sludge; and / or S14. Steam reflux, wherein the steam generated by the flash evaporator is recovered and reused, and the flash evaporator concentrates the hydrothermal decomposition products; and / or S15. Carbon source reflux, wherein the carbon source from the hydrothermal decomposition products is recovered and supplied to the anoxic biochemical tank to supply the carbon source required for the reaction.

9. The method for preparing a carbon source from a biomass hydrothermal filtrate according to claim 7, wherein, The method for preparing a carbon source from the biomass hydrothermal filtrate further comprises the following steps: S7. Solid-liquid separation of the hydrothermal decomposition products to obtain a carbon source filtrate.

10. A sludge recycling and reduction system, characterized in that, Comprising: A system for preparing a carbon source from the biomass hydrothermal filtrate according to any one of claims 1-7; And A pretreatment unit for pretreating sludge / sewage to separate impurities.

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