Method for producing small molecular organic acid and methane through anaerobic carbon metabolism based on selective release of endogenous electron shuttles of sludge and sludge deconstruction induced by ion exchange

Abstract

The invention discloses a method for producing micromolecular organic acid and methane through anaerobic carbon metabolism based on selective release of endogenous electron shuttles of sludge and sludge deconstruction induced by ion exchange, and belongs to the field of sewage sludge resourceful treatment.The method comprises the steps that feeding sludge and an ion exchanger are evenly mixed in a closed carbon metabolism reactor, then the temperature is controlled to be 35-55 DEG C, and the temperature is controlled to be 35-55 DEG C; starting of carbon metabolism reaction is completed at the stirring speed gradient of 300-600 s <-1 >, in the stable period of the carbon metabolism reaction, a mixed system with the same volume is discharged and conveyed from the closed carbon metabolism reactor, and small-molecular organic acid and methane can be produced by regulating and controlling the adding amount of the ion exchanger, the retention time and the sludge load rate; when methane is recovered, methane is collected from a closed carbon metabolism reactor, PAC or FeCl3 is used for conditioning when small-molecular organic acid is recovered, then conditioning liquid is subjected to solid-liquid separation, obtained filtrate is recovered, obtained dehydrated filtrate is rich in small-molecular organic acid, and the whole-process efficiency of anaerobic carbon metabolism is enhanced.

Description

Technical Field

[0001] The invention belongs to the field of sewage sludge resource treatment, and specifically is a method for producing small molecule organic acids and methane through anaerobic carbon metabolism based on ion exchange-induced selective release of endogenous electron shuttles in sludge and sludge deconstruction. Background Art

[0002] Anaerobic carbon metabolism is widely considered to be the preferred sludge resource utilization pathway. It has three stages, namely sludge deconstruction and hydrolysis, acidogenesis metabolism and methanogenesis metabolism. The essence of dissolution and hydrolysis is the conversion of solid carbon-containing organic substrates in sludge into soluble liquid carbon-containing organic substrates. Acidogenesis is the conversion of soluble liquid organic substrates into small molecule organic acids through microbial metabolism. Methanogenesis is the further conversion of small molecule organic acids into methane through microbial metabolism. The reaction process can be controlled to stay at acidogenesis and the carbon source can be recovered in the form of small molecule organic acids (mainly acetic acid). Alternatively, the reaction can be completed to recover methane and recover carbon energy in the form of methane. However, the thermodynamic energy barrier of the acidogenesis metabolism process is high and the microbial respiratory activity is low, which limits the conversion of organic matter into small molecule organic acids and the recovery efficiency of its carbon source. The mutual coordination of methanogenesis metabolism is poor, and the interspecies electron transfer efficiency is low, which leads to metabolic obstruction, limiting the methane yield and low carbon energy recovery rate. In addition, the rigid structure of the sludge limits the dissolution efficiency, and the release of carbon-containing organic substrates is small, which cannot provide sufficient soluble carbon-containing organic substrates for the anaerobic carbon metabolism process, and also limits the metabolic efficiency of acidogenesis and methanogenesis.

[0003] Regarding the first bottleneck problem of anaerobic carbon metabolism: high thermodynamic energy barriers in acidogenic metabolism and methanogenic metabolism, low microbial respiratory activity, poor mutual coordination, and low interspecies electron transfer efficiency, endogenous quinone electron shuttles in sludge are the original and self-owned pathways for mediating microbial respiration and interspecies electron transfer, but they are usually present in the sludge as complexes, resulting in limited endogenous mediation capacity, which is the main reason for the above-mentioned first bottleneck problem. Therefore, most of the current methods use exogenous regulation, such as adjusting the system environmental conditions (redox potential, pH, temperature), adding exogenous bacterial agents, adding exogenous conductive materials (biochar, activated carbon, magnetite), etc. However, these exogenous regulation methods all have shortcomings, such as poor effect and poor stability of the method for adjusting the system environmental conditions, and it is difficult for exogenous bacterial agents to remain stably in the sludge system for a long time, and regular addition of bacterial agents is required, and the effect is poorly stable; the method of adding exogenous conductive materials is more stable and efficient, but exogenous conductive materials are difficult to recycle and reuse, the cost is high, and the granular materials affect the operation of the system.

[0004] The second bottleneck problem of anaerobic carbon metabolism: the slow sludge dissolution rate is due to the cross-linking of carbon-containing organic substrates in the sludge with endogenous electron shuttles through metal bridging to form a rigid structure of sludge flocs. There is currently a lack of targeted solutions, and most of them are solved by applying exogenous energy or chemical agents, such as thermal hydrolysis, acid-base pretreatment, and advanced oxidation treatment. However, there are problems such as high drug / energy consumption, changes in the molecular structure of sludge organic matter and the generation of inhibitory products, and large changes in the system environment that affect subsequent disposal.

[0005] In addition, current methods usually use different means to strengthen and overcome the above two bottleneck problems respectively, and it is impossible to solve the above two bottleneck problems simultaneously through the same means. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a method for producing small molecule organic acids and methane through anaerobic carbon metabolism based on ion exchange-induced selective release of endogenous electron shuttles in sludge and sludge deconstruction. The ion exchanger weakens the metal bridging binding between the solid carbon-containing organic substrate and the endogenous electron shuttle, and selectively releases the endogenous electron shuttle in the sludge to efficiently mediate and accurately regulate the anaerobic carbon metabolism. At the same time, it weakens the binding between the solid carbon-containing organic substrate in the sludge and the endogenous electron shuttle, drives the deconstruction of sludge and the solubilization of the solid carbon-containing organic substrate, and provides soluble carbon-containing organic substrate for subsequent anaerobic carbon metabolism. Maximize the efficiency of anaerobic carbon metabolism, that is, to achieve the selective release of endogenous electron shuttles in sludge and sludge deconstruction at the same time under the same treatment method, and achieve the dual benefits of releasing endogenous electron shuttles and promoting sludge deconstruction, which can enhance the efficiency of the entire process of anaerobic carbon metabolism, and improve the recovery and enrichment rate of small molecule organic acids and methane; by releasing endogenous electron shuttles in sludge to efficiently mediate and precisely control anaerobic carbon metabolism, rather than adding exogenous conductive materials, it changes the exogenous mediated enhancement method commonly used in traditional methods, and is an innovative sludge endogenous mediated enhancement method.

[0007] The present invention is achieved through the following technical solutions: A method for producing small molecule organic acids by anaerobic carbon metabolism based on ion exchange-induced selective release of endogenous electron shuttles in sludge and sludge deconstruction, comprising the following steps: S1, the feed sludge and ion exchanger are mixed evenly in a closed carbon metabolism reactor, and the ion exchanger dosage is 10~50 mmol e - / g TS, then control the temperature to 35~55 o C, then 300~600 s -1 The stirring rate gradient of was used to start the carbon metabolism reaction and obtain a mixed system; S2, during the stable period of carbon metabolism reaction, the same volume of mixed system was discharged and transported from the closed carbon metabolism reactor, so that the ion exchanger residence time was 72~240h. At the same time, the sludge loading rate was adjusted to 1~13.33 kg TS / m by changing the sludge solid content and the ion exchanger residence time. 3 / d, the release of endogenous electron shuttles is 3.50~9.00 kg / ton TS; S3, uses PAC or FeCl3 to condition the mixed system discharged from S2 to obtain a conditioned liquid, then performs solid-liquid separation on the conditioned liquid, and then recovers the obtained filtrate to obtain a dehydrated filtrate, which is rich in small molecule organic acids, thereby completing the recovery of the small molecule organic acid carbon source.

[0008] A further improvement of the present invention is: The closed carbon metabolism reactor in S2 is equipped with a SCOD online monitor, a microbial metabolic conversion rate analyzer, an electrochemical activity meter and a volatile fatty acid online monitor to monitor the SCOD, microbial metabolic conversion rate of small molecule organic acids, electrochemical activity and small molecule organic acid production in the S2 process respectively. When the following conditions are not met, one or more of the methods 1, 2 and 3 are adopted. Method 1 is to increase the dosage of the ion exchanger in S1, method 2 is to extend the residence time of the ion exchanger, and method 3 is to reduce the sludge load rate until the following conditions are met: SCOD ≥ 20% of sludge solid content, electrochemical activity ≥ 0.3 mmol e - / g C, microbial metabolic conversion rate of small molecule organic acids ≥50%, and small molecule organic acid production ≥0.04 kg C / kg TS.

[0009] In S1, the solid content of the sludge is adjusted to 10-40 g TS / L by standing concentration or diluting with water to obtain feed sludge.

[0010] The ion exchanger described in S1 is sodium citrate, sodium pyrophosphate or ethylenediaminetetraacetic acid.

[0011] When the ion exchanger described in S1 is an insoluble solid ion exchanger, the ion exchanger is activated using 0.8~1.2 mol / L HCl solution and 0.8~1.2 mol / L NaOH solution in sequence, the activation time is 3.5~6.5h, the interval between the activation of HCl solution and NaOH solution is 1.5~3.5h, the volume ratio of HCl solution to ion exchanger is 4:1~2:1, and the volume ratio of NaOH solution to ion exchanger is 4:1~2:1.

[0012] The insoluble solid ion exchanger is ion exchange fiber, ion exchange gel, ion exchange resin or artificial zeolite.

[0013] The closed carbon metabolism reactor in S1 is an integrated container of an upper cylinder and a lower cone, the diameter of the cylinder is the same as the bottom diameter of the cone, and a number of support frames distributed obliquely outward are provided at the bottom of the cylinder. An axial flow pump is installed at the mud inlet at the bottom of the closed carbon metabolism reactor, and the feed sludge is transported from bottom to top through the axial flow pump.

[0014] S1: Mix the feed sludge and ion exchanger evenly in a closed carbon metabolism reactor. The dosage of ion exchanger is 10~50 mmol e - / g TS, and a mixed system a is obtained; S1 mixes the feed sludge and the quinone-based electron shuttle evenly, and the dosage of the quinone-based electron shuttle is 2-10 mg / g TS to obtain a mixed system b, and then controls the temperature of the mixed system b to be 35-55 o C, react for 480-720 h to obtain inoculum sludge, which is then put into the mixed system a in the closed carbon metabolism reactor. The dry matter ratio of the inoculum sludge to the feed sludge in the mixed system a is 1:10-1:20, and the temperature is controlled at 35-55 o C, 300~600 s -1 The stirring rate gradient of was used to start the carbon metabolism reaction and obtain a mixed system.

[0015] A method for producing methanogens by anaerobic carbon metabolism based on ion exchange-induced selective release of endogenous electron shuttles in sludge and sludge deconstruction, based on the above-mentioned method for producing small molecule organic acids by anaerobic carbon metabolism based on ion exchange-induced selective release of endogenous electron shuttles in sludge and sludge deconstruction, the dosage of ion exchanger in S1 is replaced by 3-10 mmol e - / gTS and then S1, the ion exchanger residence time in S2 is replaced to 240~720h, and the sludge load rate is replaced to 0.33~4 kgTS / m 3 / d later, S2 is performed, and finally S3 is replaced by collecting biogas from a closed carbon metabolism reactor, which is rich in methane, to complete the recovery of methane.

[0016] Furthermore, the closed carbon metabolism reactor in S2 is provided with a SCOD online monitor, a microbial metabolic conversion rate analyzer, an electrochemical activity meter and a methane detector to monitor the SCOD, the microbial metabolic conversion rate of methane, the electrochemical activity and the methane yield in the S2 process respectively. When the following conditions are not met, one or more of the methods 1, 2 and 3 are adopted. Method 1 is to increase the dosage of the ion exchanger in S1, method 2 is to extend the residence time of the ion exchanger, and method 3 is to reduce the sludge load rate until the following conditions are met: SCOD ≥ 20% of sludge solid content, electrochemical activity ≥ 0.3 mmol e- / g C, microbial metabolic conversion rate of methane ≥35%, methane production ≥50 m 3 / ton TS or 27 kg C / ton TS.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention discloses an anaerobic carbon metabolism method for producing small molecule organic acids based on ion exchange-induced selective release of endogenous electron shuttles in sludge and deconstruction of sludge. Combined with the design of stirring and reaction temperature, the structural metals in the sludge can be removed by ion exchange, the connection sites between the structural metals and the endogenous electron shuttles in the sludge can be broken, the metal complexing force of the endogenous electron shuttles in the sludge can be weakened, and the binding of the sludge flocs to the endogenous electron shuttles can be weakened. According to the strength and spatial distribution of the metal complexing ability of different endogenous electron shuttles, only low energy is needed to quickly promote the selective release of the endogenous electron shuttles from the solid phase of the sludge, change the occurrence state and mass transfer conditions of the endogenous electron shuttles in the sludge system, and transform the endogenous electron shuttles from the solid phase bound state to the liquid phase dissolved state. At the same time, the stirring rate gradient is controlled at 300-600 s -1 , which can ensure the contact efficiency between ion exchangers, endogenous electron shuttles, functional bacteria, and carbon-containing organic substrates, and ensure the mass transfer of ion exchange reactions and anaerobic carbon metabolism reactions. Endogenous electron shuttles have functional groups with electron shuttle capabilities such as quinones and phenolic hydroxyl groups. Their selective release leads to the presence of more electron shuttle media in the carbon metabolism reactor, which can play the role of conductive materials and regulate the anaerobic carbon metabolism pathway and activity. After release, endogenous electron shuttles act as electron acceptors to mediate extracellular respiration, reduce the activation energy of anaerobic metabolism, increase metabolic activity and regulate metabolic pathways, and can improve the recovery efficiency of small molecule organic acids (carbon sources). The present invention can increase the release of endogenous electron shuttles in sludge by 8.2-13.8 times, electrochemical activity by 2.8-3.2 times, SCOD by 1.98-2.08 times, functional enzyme activity by 1.5-1.9 times, and microbial metabolic conversion rate by 1.3-1.4 times by controlling the dosage of ion exchanger, ion exchanger residence time, and sludge load rate. It can promote the conversion of soluble carbon-containing organic substrates into small molecule organic acids under anaerobic carbon metabolism, break through the bottleneck of acid production efficiency in the anaerobic carbon metabolism process of sludge, and improve the recovery efficiency of carbon sources. The present invention does not need to add exogenous conductive materials, but uses ion exchange to release the endogenous electron shuttles of sludge into the liquid phase environment, which acts as a conductive material, changing the exogenous mediated synergistic method commonly used in traditional methods, and avoiding the increase of sludge substances and system operation problems caused by the residue of exogenous conductive materials.

[0018] The present invention discloses an anaerobic carbon metabolism methanogenesis method based on ion exchange-induced selective release of endogenous electron shuttles in sludge and sludge deconstruction. The method utilizes the same mechanism as the production of small molecule organic acids, selectively releases endogenous electron shuttles by ion exchange, and can improve the contact mass transfer between endogenous electron shuttles and methane functional bacteria and carbon-containing organic substrates, so that they can play the role of conductive materials. Endogenous electron shuttles mediate interspecies electron transfer as electron carriers, provide channels for rapid electron transfer, coordinate mutual metabolic relationships, improve the mutual coordination of anaerobic carbon metabolism, improve metabolic activity and regulate metabolic pathways, and improve the yield of methane (carbon energy). The present invention controls the dosage of ion exchanger, the residence time of ion exchanger and the sludge loading rate, so that the release of endogenous electron shuttles in sludge can be increased by 8.2-13.8 times, the electrochemical activity can be increased by 2.8-3.2 times, the functional enzyme activity can be increased by 1.5-1.9 times, the microbial metabolic conversion rate can be increased by 1.3-1.4 times, small molecule organic acids can be further metabolically converted by microorganisms, and soluble carbon-containing organic substrates can be promoted to be converted into methane under the action of anaerobic carbon metabolism, thus breaking through the bottleneck of methane production efficiency in the anaerobic carbon metabolism process of sludge and improving the recovery efficiency of carbon energy.

[0019] Furthermore, by adjusting the ion exchanger dosage, ion exchanger residence time, and sludge load rate operating parameters, not only can the release amount, release type, and sludge decomposition rate of endogenous electron shuttles in sludge be selectively controlled, but also the anaerobic carbon metabolism reaction stage and the recovered products can be controlled. At the same time, it has the advantages of shortening the cycle, improving product recovery rate, improving stability, mild system conditions, and flexible operation and regulation. The mechanism of action is derived from endogenous regulation of sludge, does not consume excessive chemical agents or energy, and has significant economic and environmental benefits.

[0020] Furthermore, by adding commercial quinone-based electron shuttles to the feed sludge, the sludge bacterial community can be adapted to the electron-mediated environment of the quinone-based electron shuttles, functional bacterial communities can be screened and the inoculated sludge can be domesticated. The domesticated inoculated sludge is then added into the closed carbon metabolism reactor, which can provide an adaptive functional bacterial community to the initial environment, thereby enabling the closed carbon metabolism reactor to quickly respond to the release of endogenous electron shuttles in the sludge and their mediated environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments will be introduced below. Obviously, the drawings described below are an embodiment of the present invention. For ordinary technicians in this field, other drawings can be obtained without paying creative work.

[0022] Figure 1 Schematic diagram of the auxiliary device used in the method of the present invention.

[0023] Figure 2aThis is the sludge solid reduction effect when the recovery of small molecule organic acid (carbon source) is the goal in Example 1 of the present invention.

[0024] Figure 2b This is the SCOD in Example 1 of the present invention when the recovery of small molecule organic acids (carbon sources) is the goal.

[0025] Figure 3a It is the amount of endogenous electron shuttles released from sludge when the recovery of small molecule organic acids (carbon sources) is the goal in Example 1 of the present invention.

[0026] Figure 3b It is the electrochemical activity when the recovery of small molecule organic acid (carbon source) is the goal in Example 1 of the present invention.

[0027] Figure 4 It is the functional enzyme activity when the recovery of small molecule organic acid (carbon source) is the goal in Example 1 of the present invention.

[0028] Figure 5 It is the microbial metabolic conversion rate when the recovery of small molecule organic acid (carbon source) is the goal in Example 1 of the present invention.

[0029] Figure 6 It is the small molecule organic acid yield when the recovery of small molecule organic acid (carbon source) is the goal in Example 1 of the present invention.

[0030] Figure 7a This is the sludge solid reduction effect when the goal is to recover methane (carbon energy) in Example 3 of the present invention.

[0031] Figure 7b This is the SCOD in Example 3 of the present invention when the goal is to recover methane (carbon energy).

[0032] Figure 8a It is the amount of endogenous electron shuttle released from sludge when methane (carbon energy) is the target in Example 3 of the present invention.

[0033] Figure 8b This is the electrochemical activity when the goal is to recover methane (carbon energy) in Example 3 of the present invention.

[0034] Fig. 9 This is the functional enzyme activity when methane (carbon energy source) is the target in Example 3 of the present invention.

[0035] Fig.10 It is the microbial metabolic conversion rate when methane (carbon energy) is the target in Example 1 of the present invention.

[0036] Fig.11 It is the methane production when methane (carbon energy) is the target in Example 1 of the present invention.

[0037] Fig.12 It is a technical idea diagram of the present invention.

[0038] In the figure: 1-activation tank; 2-ion exchanger; 3-closed carbon metabolism reactor; 4-endogenous electron shuttle; 5-dosing port; 6-sludge discharge port; 7-heating temperature control device; 8-SCOD online monitor; 9-electrochemical activity analyzer; 10-volatile fatty acid online monitor; 11-methane detector; 12-microorganism metabolic conversion rate analyzer; 13-gas collection device; 14-double-layer stirring device; 15-support frame; 16-axial flow pump; 17-dehydration tank; 18-filtrate recovery device; 19-sludge solid content adjustment tank. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0040] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] The inventive point of the present invention is that there are a large number of quinone substances in the sludge, which can act as endogenous electron shuttles to mediate microbial extracellular respiration and interspecies electron transfer. However, these endogenous electron shuttles are usually present in the form of metal complexes inside the sludge, which hinders contact mass transfer and limits its mediation and regulatory functions. If these endogenous electron shuttles can be released and used to replace exogenous conductive materials, the endogenous mediation of sludge can be enhanced, breaking through the first bottleneck problem of the above-mentioned anaerobic carbon metabolism. At the same time, the endogenous electron shuttles in the sludge are cross-linked with the carbon-containing organic substrate to form a rigid structure of sludge flocs, which hinder each other from dissolving and releasing. If the endogenous electron shuttles in the sludge can be selectively released, the sludge deconstruction can be driven synchronously, prompting the carbon-containing organic substrate to be dissolved and released from the sludge solid phase to the liquid phase, providing a substrate for anaerobic carbon metabolism, breaking through the second bottleneck problem of the above-mentioned anaerobic carbon metabolism. Therefore, it is necessary to develop a method to weaken the metal complex binding force between endogenous electron shuttles and carbon-containing organic substrates in sludge, disintegrate the complex connection between endogenous electron shuttles-carbon-containing organic substrates-metals, thereby promoting the selective release of endogenous electron shuttles, and at the same time promoting sludge deconstruction and solubilization of carbon-containing organic substrates, while breaking through the two major bottleneck problems of sludge anaerobic carbon metabolism, and enhancing sludge anaerobic carbon metabolism to produce small molecule organic acids (carbon sources) or methane (carbon energy).

[0042] Based on this, the present invention provides a method for producing small molecule organic acids and methane through anaerobic carbon metabolism based on ion exchange-induced selective release of endogenous electron shuttles in sludge and sludge deconstruction, such as Fig.12 As shown, the selective release of endogenous electron shuttles in sewage sludge (hereinafter referred to as sludge) is mainly induced by the ion exchange method, and it is used as a conductive material to mediate extracellular respiration and interspecies electron transfer, reduce the thermodynamic energy barrier of anaerobic carbon metabolism reactions, improve extracellular respiration activity and interspecies electron transfer efficiency, coordinate mutual metabolic relationships, and enhance the conversion efficiency of carbon-containing organic substrates. At the same time, it promotes sludge deconstruction and solubilization of carbon-containing organic substrates, thereby driving the entire process of anaerobic carbon metabolism. By adjusting the operating parameters, the final product can be controlled to be small molecule organic acid (carbon source recovery) or methane (carbon energy recovery). The overall implementation methods and processes of the two processes are similar, but there are differences in ion exchanger dosage, ion exchanger residence time, sludge load rate and parameter monitoring. The implementation process of the present invention is assisted by the following Figure 1 The device shown. 1. Specific implementation method 1: This implementation method is completed according to the following steps.

[0043] (1) adjusting the sludge solid content to 10-40 g TS / L in the sludge solid content adjustment tank 19 by standing and concentrating or diluting with water to obtain feed sludge; (2) In the activation pool 1, 0.8-1.2 mol / L HCl solution and 0.8-1.2 mol / L NaOH solution are used to activate the ion exchanger 2 in turn, so as to enhance the loading capacity of the active ions of the ion exchanger; the activation time is 3.5-6.5 h, the interval time between the activation of HCl and NaOH solutions is 1.5-3.5 h, that is, the time for washing with clean water, the volume ratio of HCl solution to ion exchanger is 4:1-2:1, and the volume ratio of NaOH solution to ion exchanger is 4:1-2:1; the specification of the activation pool 1 is a stainless steel cylindrical pool with R (radius): H (height) = 1:2; the ion exchanger 2 used is an insoluble solid ion exchanger, including ion exchange fiber, ion exchange gel, ion exchange resin, and artificial zeolite; (3) The feed sludge and quinone-based electron shuttle were mixed evenly, and the dosage of quinone-based electron shuttle was 2-10 mg / g TS. Then the temperature was controlled at 35-55 o C, react for 480-720 h to obtain inoculum sludge; (4) Add the activated ion exchanger 2 into the closed carbon metabolism reactor 3 through the valve of the addition port 5. The amount of ion exchanger added (in terms of exchange capacity equivalent) is 10-50 mmol e - / g TS, the feed sludge is fed into the closed carbon metabolism reactor 3 by the axial flow pump 16 every 20-28 h, and the double-layer stirring device 14 is used to achieve full mixing, so that the ion exchanger 2 and the feed sludge are evenly mixed, the structural metal of the sludge is removed, the endogenous electron shuttle 4 is released, and the sludge is decomposed to obtain a mixed system; then, the inoculated sludge is fed into the closed carbon metabolism reactor 3 by the axial flow pump 16, the dry matter ratio of the inoculated sludge to the feed sludge is 1:10-1:20, and the reaction temperature of the mixed system is controlled by the heating temperature control device 7 to be 35-55 o C, maintain a sealed anaerobic environment, and complete the startup of the closed carbon metabolism reactor 3; the stirring device includes a motor and a stirring paddle, and the stirring rate gradient is controlled at 300~600 s -1 , ensuring the contact efficiency between the ion exchanger 2, sludge, endogenous electron shuttle 4, and functional bacteria, and ensuring the mass transfer of ion exchange reaction and anaerobic carbon metabolism reaction; the closed carbon metabolism reactor 3 is a stainless steel integrated container with an upper cylinder and a lower cone, the diameter of the cylinder is the same as the bottom diameter of the cone, and there are three support frames 15 distributed obliquely outward at the bottom of the cylinder, and an axial flow pump 16 is installed at the mud inlet located at the center of the bottom, which completes the sludge transportation and feeding from the bottom of the lower cone; (5) During the stable period of the closed carbon metabolism reactor 3, the mixed system of ion exchanger and sludge is discharged from the valve of the sludge discharge port 6 every 20 to 28 hours, and the discharge volume is 1 / 10 to 1 / 3 of the volume of the closed carbon metabolism reactor; the feed sludge is uniformly and synchronously transported by the axial flow pump 16, and the ion exchanger corresponding to the amount of sludge is added from the valve of the ion exchanger addition port 5, and the ion exchanger addition amount (in terms of exchange capacity equivalent) is 10 to 50 mmol e - / g TS, the sum of the volumes of the added feed sludge and activated ion exchanger is equal to the volume of the discharged mixed system; the process controls the ion exchanger residence time by changing the volume of the mixed system discharged each time, and the ion exchanger residence time is 72~240h, and the calculation formula is as follows; at the same time, the sludge loading rate is regulated by changing the sludge solid content and the ion exchanger residence time, and the sludge loading rate should be between 1~13.33 kg TS / m 3 / d range;

[0044] (6) Control the reaction temperature of the mixed system in the closed carbon metabolism reactor to 35~55 o C, continue to maintain the anaerobic environment, while maintaining the stirring speed gradient of 300~600 s -1 , anaerobic carbon metabolism reaction, the endogenous electron shuttle release in this process is 3.50~9.00 kg / ton TS, and the electrochemical activity is ≥0.3 mmol e - / g C, SCOD ≥ 20% of the solid content of the sludge, the released endogenous electron shuttle can mediate extracellular respiration and interspecies electron transfer, reduce thermodynamic energy barriers, improve the efficiency of extracellular respiration, coordinate mutualistic metabolic relationships, strengthen the bioelectrochemical reaction process of anaerobic carbon metabolism, and promote the metabolic transformation of carbon-containing organic substrates. At the same time, sludge deconstruction can provide sufficient soluble carbon-containing organic substrates for anaerobic carbon metabolic reactions; the device and method for temperature control and stirring control are the same as those in step (4); (7) During the operation of the above steps (5) to (6), a monitoring module is set up, including a SCOD online monitor 8, a microbial metabolic conversion rate analyzer 12, an electrochemical activity meter 9, and a volatile fatty acid online monitor 10 to evaluate the operation effect and stability, and a feedback adjustment process is provided. The monitoring results should meet the following ranges: a. Use SCOD online monitor 8 to monitor SCOD value to evaluate sludge decomposition rate. It is necessary to ensure that SCOD ≥ 20% of sludge solid content; b. Use electrochemical activity meter 9 to monitor the electrochemical activity. The electrochemical activity should be ≥ 0.3 mmol e - / gC, the released endogenous electron shuttles can mediate electron transfer, reduce the thermodynamic energy barrier of metabolism, improve the efficiency of extracellular respiration, coordinate the mutual metabolic relationship, and strengthen the entire process of anaerobic carbon metabolism; c. Monitor the microbial metabolic conversion rate using a microbial metabolic conversion rate analyzer 12, and ensure that the microbial metabolic conversion rate of small molecule organic acids is ≥50%; d. Use the volatile fatty acid online monitor 10 to monitor the content of small molecule organic acids, and ensure that the output of small molecule organic acids is ≥ 0.04 kg C / kg TS; If the above monitoring indicators do not meet the requirements, according to the above operating parameter range and operation adjustment method of the present invention, the dosage of the ion exchanger can be increased, or the volume of the mixed system discharged every 20 to 28 hours can be reduced to extend the residence time of the ion exchanger, or the solid content of the sludge can be reduced to reduce the sludge load rate. The three operating parameters of the above closed carbon metabolism reactor can be adjusted separately or simultaneously, so as to regulate the operating state and ensure the efficient and stable anaerobic carbon metabolism reaction; (7) The mixed system discharged from the closed carbon metabolism reactor 3 is discharged into the dehydration tank 17 every 20 to 28 hours, and is conditioned by polyaluminium chloride (PAC) or FeCl3, with the addition concentration of PAC or FeCl3 being 0.1 to 0.5 g / g TS to obtain a conditioned mixture, and then the conditioned mixture is subjected to solid-liquid separation by a mechanical dehydration device, and is recovered by a filtrate recovery device 18 to obtain a dehydrated filtrate, which is rich in small molecule organic acids and is the recovered carbon source liquid, which can be used as an additional carbon source for sewage treatment, or as a high-quality carbon source for biohydrogen production, bioelectricity production, and plastic synthesis, and has a high added value; (8) Steps (1), (2), (4), (5), (6), (7), and (8) are repeated cyclically to achieve semi-continuous flow operation.

[0045] 2. Specific implementation method 2: This implementation method differs from specific implementation method 1 in that the ion exchanger used is a soluble liquid ion exchanger, including sodium citrate, sodium pyrophosphate, and ethylenediaminetetraacetic acid, and the implementation process does not require the execution of step (2); the rest is the same as specific implementation method 1.

[0046] 3. Specific embodiment 3: The difference between this embodiment and specific embodiment 1 is that the dosage of ion exchanger in steps (4) and (5) (in terms of exchange capacity equivalent) is 3-10 mmol e - / g TS, the volume of the discharged mixed system is 1 / 30~1 / 10 of the total volume of the closed carbon metabolism reactor 3, the residence time of the ion exchanger is 240~720h, and the sludge loading rate should be between 0.33~4 kg TS / m 3 / d; in step (7), the volatile fatty acid online analyzer 10 is not used to monitor the small molecule organic acid content, but the methane detector 11 is used to monitor the methane volume, and the monitoring result c is that the microbial metabolic conversion rate of methane is ≥35%, and the monitoring result d is that the methane production is not less than 50 m 3 / ton TS (27 kg C / ton TS); the final product recovered in step (8) is methane, and the biogas is collected from the gas collection device 13 at the top of the closed carbon metabolism reactor 3, which is rich in methane and can be recovered and used as carbon energy gas, while the mixed system discharged from the closed carbon metabolism reactor can be transported out for disposal; the rest is the same as the specific implementation method one.

[0047] 4. Specific implementation method four: This implementation method is different from specific implementation method three in that the ion exchanger used is a soluble liquid ion exchanger, including sodium citrate, sodium pyrophosphate, and ethylenediaminetetraacetic acid, and the implementation process does not need to perform step (2); the rest is the same as specific implementation method three.

[0048] Embodiment 1: In the decentralized sewage treatment plant, the sludge was treated for resource recovery in situ. When the sludge moisture content was higher than 99%, the sludge solid content was adjusted to 20 g TS / L by static concentration to obtain the feed sludge. The added insoluble solid ion exchanger was a macroporous ion exchange resin (D001). The ion exchanger was activated for 2 hours with 1 mol / L HCl solution in the activation tank. The volume ratio of HCl solution to ion exchanger was 3:1. The ion exchanger was taken out and soaked in clean water for 2 hours. Then, the ion exchanger was activated for 2 hours with 1 mol / L NaOH solution. The volume ratio of NaOH solution to ion exchanger was 3:1. The ion exchanger was then separated from the activation tank.

[0049] The feed sludge and quinone-based electron shuttle AQDS (anthraquinone-2,6-sodium sulfonate) were mixed evenly, and the dosage of quinone-based electron shuttle was 8 mg / g TS. Then the temperature was controlled at 40 o C, reaction time 600 h, obtaining inoculum sludge; This example uses small molecule organic acids as the final product and carbon source recovery as the ultimate goal. 1 L of feed sludge was added into the closed carbon metabolism reactor, and then 70 g of activated ion exchanger was added into the closed carbon metabolism reactor. The amount of ion exchanger (in terms of exchange capacity equivalent) was 15 mmol e - / g TS. The double-layer stirring device 14 is used to achieve full mixing, so that the ion exchanger and the feed sludge are evenly mixed to obtain a mixed system of the activated ion exchanger and the feed sludge. Then, the seeded sludge is put into the closed carbon metabolism reactor, the dry matter ratio of the seeded sludge to the feed sludge is 1:15, and the reaction temperature of the mixed system is controlled to be 37 o C, maintain a sealed anaerobic environment, complete the start-up of the closed carbon metabolism reactor, and control the stirring speed gradient to 400 s -1 Since the density of the macroporous ion exchange resin is 1.25 kg / L, the total volume of the mixed system is 1.056 L. Then, the closed carbon metabolism reactor enters the stable period. Every 24 h, 0.264 L of the mixed system is discharged from the closed carbon metabolism reactor, and then 0.25 L of fresh feed sludge and 17.5 g of activated ion exchanger are added, that is, the feed and discharge are 1 / 4 of the volume of the closed carbon metabolism reactor. At this time, the ion exchanger residence time is 96 h, and the sludge loading rate is 5 kg TS / m 3 / d. The process adopts semi-continuous flow operation mode, controls the closed carbon metabolism reactor to anaerobic conditions, and continuously maintains the stirring speed gradient of 400 s -1 The reaction temperature is 37 oC, anaerobic carbon metabolism reaction, during the operation, the operation parameters (ion exchanger dosage, mixed system volume discharged, sludge solid content) were adjusted, SCOD, electrochemical activity, microbial metabolic conversion rate, and small molecule organic acid content were monitored, and it was found that the above four indicators met SCOD ≥ 20% of sludge solid content, electrochemical activity ≥ 0.3 mmol e - / gC, microbial metabolic conversion rate ≥50%, small molecule organic acid production not less than 0.04 kg C / kg TS. PAC was used to condition the mixed system discharged from the closed carbon metabolism reactor, with a PAC dosage of 0.3 g / g TS, and then 12m 2 The plate and frame filter press performs dehydration and solid-liquid separation, and the obtained filtrate is the carbon source liquid, which can be recycled as a carbon source.

[0050] After actual testing and analysis, ion exchange treatment significantly induced the solubilization of sludge components and the decomposition of sludge. Figure 2a and Figure 2b It can be seen that the sludge solid reduction is as high as 0.12 kg C / kg TS, and the SCOD / sludge solid content is as high as 22.94%, which are 2.05 times and 1.98 times that of the control group respectively. Figure 3a and Figure 3b It can be seen that the release of endogenous electron shuttles induced by ion exchange treatment is 4.84 kg / ton TS, and the corresponding electrochemical activity is 0.51 mmol e - / g C, which was significantly higher than that of the control group, indicating that ion exchange effectively induced the selective release of endogenous electron shuttles and played a mediating role. Endogenous electron shuttles in sludge have functional groups with electron shuttle capabilities such as quinone and phenolic hydroxyl groups, which improve the efficiency and activity of anaerobic carbon metabolism under their mediating function. Figure 4 The activities of butyrate kinase and acetate kinase increased to 12.68 and 6.01 U / g TS, respectively, which were significantly higher than those in the control group. The acidification functional enzyme activity can promote the conversion of carbon-containing organic substrates into small molecular organic acids during anaerobic carbon metabolism. Figure 5 The microbial metabolic conversion rate was increased to 62.49%, significantly higher than the 49.63% in the control group, indicating that 62.49% of the dissolved carbon-containing organic substrates were metabolized into small molecular organic acids. Figure 6 The production of small and medium-molecule organic acids increased to 0.049 kg C / kg TS, which was 2.58 times that of the control group. This confirmed the effect of ion exchange-induced selective release of endogenous electron shuttles on anaerobic carbon metabolism and greatly enhanced the recovery of carbon sources in the form of small-molecule organic acids. These small-molecule organic acids have high bioavailability and are considered to be the preferred carbon source in the field of biochemical engineering.

[0051] Embodiment 2: The dewatered sludge produced by the decentralized sewage treatment plant is collected and transported to a unified sludge treatment station for centralized ex situ treatment. The moisture content of the dewatered cake is less than 75%. The solid content of the sludge is regulated to 30 g TS / L by adding water for dilution to obtain the feed sludge. The soluble ion exchanger added is sodium citrate (industrial grade), and no activation treatment is required.

[0052] The feed sludge and quinone-based electron shuttle AQDS were mixed evenly, and the dosage of quinone-based electron shuttle was 8 mg / g TS. Then the temperature was controlled at 40 o C, reaction time 600 h, obtaining inoculum sludge; This example uses small molecule organic acids as the final product and carbon source recovery as the ultimate goal. 1 L of feed sludge was added into the closed carbon metabolism reactor, and then 73.5 g of activated ion exchanger was added into the closed carbon metabolism reactor. The amount of ion exchanger (in terms of exchange capacity equivalent) was 25 mmol e - / g TS. The double-layer stirring device 14 is used to achieve full mixing, so that the ion exchanger and the feed sludge are evenly mixed to obtain a mixed system of the activated ion exchanger and the feed sludge. Then, the seeded sludge is put into the closed carbon metabolism reactor, the dry matter ratio of the seeded sludge to the feed sludge is 1:15, and the reaction temperature of the mixed system is controlled to be 35 o C, maintain the sealed anaerobic environment, complete the start-up of the closed carbon metabolism reactor, and control the stirring speed gradient to 350 s -1 Then, the closed carbon metabolism reactor entered the stable period. Every 24 h, 0.25 L of the mixed system was discharged from the closed carbon metabolism reactor, and then 0.25 L of fresh feed sludge and 18.375 g of activated ion exchanger were added, that is, the feed and discharge were 1 / 4 of the volume of the closed carbon metabolism reactor. At this time, the ion exchanger residence time was 96 h, and the sludge loading rate was 7.5 kg TS / m 3 / d. The process adopts semi-continuous flow operation mode, controls the closed carbon metabolism reactor to anaerobic conditions, and continuously maintains the stirring speed gradient of 350 s -1 The reaction temperature is 35 o C, anaerobic carbon metabolism reaction was carried out, and the operation parameters were adjusted during operation, and SCOD, electrochemical activity, microbial metabolic conversion rate and small molecule organic acid content were monitored. It was found that the above four indicators met the conditions of SCOD ≥ 20% of sludge solid content, electrochemical activity ≥ 0.3 mmol e - / g C, microbial metabolic conversion rate ≥50%, small molecule organic acid production not less than 0.04 kg C / kg TS. The mixed system discharged from the closed carbon metabolism reactor was conditioned with FeCl3, the PAC dosage was 0.4 g / g TS, and then 12m 2The plate and frame filter press performs dehydration and solid-liquid separation, and the obtained filtrate is the carbon source liquid, which can be recycled as a carbon source.

[0053] According to actual testing and analysis, the solid reduction of sludge treated by ion exchange reached 0.14 kg C / kg TS, the SCOD / sludge solid content was 23.78%, the release of endogenous electron shuttles in sludge was 6.22 kg / ton TS, and the corresponding electrochemical activity was 0.69 mml e - / g C, the activities of butyrate kinase and acetate kinase increased to 14.16 and 7.25 U / g TS, respectively, the microbial metabolic conversion rate increased to 69.13%, and the production of small molecule organic acids increased to 0.056 kg C / kg TS.

[0054] Embodiment 3: In the decentralized urban sewage treatment plant, the sludge was treated in situ for resource utilization. When the sludge moisture content was higher than 99%, the sludge solid content was adjusted to 15 g TS / L by sludge concentration to obtain the feed sludge. The added insoluble solid ion exchanger was a gel-type ion exchange resin (001×7). The ion exchanger was activated in the activation tank with 1 mol / L HCl solution for 1 h, and the volume ratio of HCl solution to ion exchanger was 4:1. The ion exchanger was taken out and soaked in clean water for 2 h, and then activated with 1 mol / L NaOH solution for 1 h, and the volume ratio of NaOH solution to ion exchanger was 4:1. After that, the ion exchanger was separated from the activation tank.

[0055] The feed sludge and quinone-based electron shuttle AQDS were mixed evenly, and the dosage of quinone-based electron shuttle was 8 mg / g TS. Then the temperature was controlled at 40 o C, reaction time 600 h, obtaining inoculum sludge; This example uses methane as the final product and carbon energy recovery as the ultimate goal. 1 L of feed sludge was added into the closed carbon metabolism reactor, and then 23 g of activated ion exchanger was added into the closed carbon metabolism reactor. The amount of ion exchanger (in terms of exchange capacity equivalent) was 7 mmol e - / g TS. The double-layer stirring device 14 is used to achieve full mixing, so that the ion exchanger and the feed sludge are evenly mixed to obtain a mixed system of the activated ion exchanger and the feed sludge. Then, the seeded sludge is put into the closed carbon metabolism reactor, the dry matter ratio of the seeded sludge to the feed sludge is 1:15, and the reaction temperature of the mixed system is controlled to be 45 o C, maintain a sealed anaerobic environment, complete the start-up of the closed carbon metabolism reactor, and control the stirring speed gradient to 450 s -1. Since the density of the gel-type ion exchange resin is 1.25 kg / L, the total volume of the mixed system is 1.0184 L. Then, the closed carbon metabolism reactor enters the stable period. Every 24 h, 0.04074 L of the mixed system is discharged from the closed carbon metabolism reactor, and then 0.04 L of fresh feed sludge and 0.92 g of activated ion exchanger are added, that is, the input and output are 1 / 25 of the volume of the closed carbon metabolism reactor. At this time, the ion exchanger residence time is 600 h, and the sludge loading rate is 0.6 kg TS / m 3 / d. The process adopts semi-continuous flow operation mode, controls the closed carbon metabolism reactor to anaerobic conditions, and continuously maintains the stirring speed gradient of 450 s -1 The reaction temperature is 45 o C, anaerobic carbon metabolism reaction was carried out, and the operation parameters were adjusted during operation, and SCOD, electrochemical activity, microbial metabolic conversion rate and small molecule organic acid content were monitored. It was found that the above four indicators met the conditions of SCOD ≥ 20% of sludge solid content, electrochemical activity ≥ 0.3 mmol e - / g C, microbial metabolic conversion rate ≥35%, methane production not less than 50 m 3 / ton TS (27 kg C / ton TS). The gas is collected from the gas collection device at the top of the closed carbon metabolism reactor. The gas is rich in methane and can be recycled as carbon energy gas.

[0056] After actual testing and analysis, ion exchange treatment significantly induced the solubilization of sludge components and the decomposition of sludge. Figure 7a and Figure 7b It can be seen that the sludge solid reduction is as high as 0.17 kg C / kg TS, and the SCOD / sludge solid content is as high as 34.72%, which are 2.00 times and 2.08 times that of the control group respectively. Figure 8a and Figure 8b It can be seen that the release of endogenous electron shuttles induced by ion exchange treatment is 6.70 kg / ton TS, and the corresponding electrochemical activity is 0.74 mmol e - / g C, which was significantly higher than that of the control group, indicating that ion exchange effectively induced the selective release of endogenous electron shuttles and played a mediating role. Endogenous electron shuttles in sludge have functional groups with electron shuttle capabilities such as quinone and phenolic hydroxyl groups, which improve the efficiency and activity of anaerobic carbon metabolism under their mediating function. Fig. 9 The activities of butyrate kinase, acetate kinase and coenzyme F420 increased to 10.72, 5.59 and 2.73 U / g TS, respectively, which were significantly higher than those in the control group. The activities of acidification and methanogenic enzymes can increase the conversion of carbon-containing organic substrates into methane during anaerobic carbon metabolism. Fig.10The microbial metabolic conversion rate increased to 41.14%, significantly higher than the 32.59% in the control group, indicating that 41.14% of the dissolved carbon-containing organic substrates were metabolized into methane. Fig.11 The methane production increased to 88.89 m 3 / ton TS (48 kg C / ton TS), which is 2.67 times that of the control group, confirms the effect of ion exchange-induced selective release of endogenous electron shuttles on anaerobic carbon metabolism and greatly enhances carbon energy recovery in the form of methane.

[0057] Embodiment 4: The dewatered sludge produced by decentralized sewage treatment plants is collected and transported to a unified sludge treatment station for centralized ex situ treatment. The moisture content of the dewatered cake is less than 75%. The solid content of the sludge is regulated to 30 g TS / L by adding water to dilute it, and the feed sludge is obtained. The soluble ion exchanger added is sodium pyrophosphate (industrial grade), and no activation treatment is required.

[0058] The feed sludge and quinone-based electron shuttle AQDS were mixed evenly, and the dosage of quinone-based electron shuttle was 8 mg / g TS. Then the temperature was controlled at 40 o C, reaction time 600 h, obtaining inoculum sludge; This example uses methane as the final product and carbon energy recovery as the ultimate goal. 1 L of feed sludge was added into the closed carbon metabolism reactor, and then 18 g of activated ion exchanger was added into the closed carbon metabolism reactor. The amount of ion exchanger (in terms of exchange capacity equivalent) was 9 mmol e - / g TS. The double-layer stirring device 14 is used to achieve full mixing, so that the ion exchanger and the feed sludge are evenly mixed to obtain a mixed system of the activated ion exchanger and the feed sludge. Then, the seeded sludge is put into the closed carbon metabolism reactor, the dry matter ratio of the seeded sludge to the feed sludge is 1:15, and the reaction temperature of the mixed system is controlled to be 45 o C, maintain the sealed anaerobic environment, complete the start-up of the closed carbon metabolism reactor, and control the stirring speed gradient to 350 s -1 Then, the closed carbon metabolism reactor entered the stable period. Every 24 h, 0.25 L of the mixed system was discharged from the closed carbon metabolism reactor, and then 0.25 L of fresh feed sludge and 0.72 g of activated ion exchanger were added, that is, the feed and discharge were 1 / 25 of the volume of the closed carbon metabolism reactor. At this time, the ion exchanger residence time was 600 h, and the sludge loading rate was 1.2 kg TS / m 3 / d. The process adopts semi-continuous flow operation mode, controls the closed carbon metabolism reactor to anaerobic conditions, and continuously maintains the stirring speed gradient of 350 s -1 The reaction temperature is 45o C, anaerobic carbon metabolism reaction was carried out, and the operation parameters were adjusted during operation, and SCOD, electrochemical activity, microbial metabolic conversion rate and small molecule organic acid content were monitored. It was found that the above four indicators met the conditions of SCOD ≥ 20% of sludge solid content, electrochemical activity ≥ 0.3 mmol e - / g C, microbial metabolic conversion rate ≥35%, methane production not less than 50 m 3 / ton TS (27 kg C / ton TS). The gas is collected from the gas collection device at the top of the closed carbon metabolism reactor. The gas is rich in methane and can be recycled as carbon energy gas.

[0059] According to actual testing and analysis, the solid reduction of sludge treated by ion exchange reached 0.18 kg C / kg TS, the SCOD / sludge solid content was 34.61%, the release of endogenous electron shuttles in sludge was 6.44 kg / ton TS, and the corresponding electrochemical activity was 0.67 mml e - / g C, the activities of butyrate kinase, acetate kinase and coenzyme F420 increased to 11.35, 5.27 and 2.24 U / g TS, respectively, the microbial metabolic conversion rate increased to 38.18%, and the methane production increased to 83.34 m 3 / ton TS (45 kg C / ton TS).

[0060] The present invention has excellent controllability in terms of operation mode, effect, application scenario and product recovery category; by adjusting the dosage of ion exchanger, the residence time of ion exchanger and the sludge load rate, the type and amount of endogenous electron shuttle release can be selectively regulated, thereby accurately regulating its spatial occurrence state in the system, with high accuracy and controllability; during operation, SCOD, electrochemical activity, microbial metabolic conversion rate, small molecule organic acid content and methane content indicators are monitored, and the operation parameters are feedback-regulated to achieve dynamic regulation and stable operation of the system; in addition, the present invention is applicable to a variety of scenarios, and the ion exchanger can use an insoluble solid ion exchanger or a soluble liquid ion exchanger. The final recovered product can be a small molecule organic acid or methane. By changing the residence time of the ion exchanger, the reaction process is regulated to stay in the acid production stage or the methane production stage, thereby controlling the category of the final product, which has an enhancing effect on the recovery of both products.

[0061] The present invention disintegrates the metal complex connection of the sludge components by ion exchange method, synchronously induces the selective release of endogenous electron shuttles and promotes sludge deconstruction, changes the state of endogenous electron shuttles, realizes endogenous mediated synergism, not only improves the activity and efficiency of anaerobic carbon metabolism, but also regulates the anaerobic carbon metabolism pathway, enhances the bioconversion of sludge solid phase macromolecular carbon-containing organic substrates to small molecule organic acids or methane, and increases the content of soluble carbon-containing organic substrates, so that it can be used for anaerobic carbon metabolism, and ultimately greatly improves the overall process efficiency of sludge anaerobic carbon metabolism, maximizes the accumulation of small molecule organic acids to achieve carbon source recovery, or accumulates methane to achieve carbon energy recovery, and improves product recovery and enrichment rate. The present invention can simultaneously solve the restrictions on the anaerobic carbon metabolism process caused by high thermodynamic energy barriers, low metabolic activity, poor mutual coordination, low interspecies electron transfer efficiency, low carbon-containing organic substrate conversion efficiency, and slow sludge dissolution rate.

Claims

1. A method for producing small molecule organic acids by anaerobic carbon metabolism based on ion exchange-induced selective release of endogenous electron shuttles in sludge and sludge deconstruction, characterized in that: The following steps are involved: S1, the feed sludge and ion exchanger are mixed evenly in a closed carbon metabolism reactor, and the ion exchanger dosage is 10~50 mmol e - / g TS, then control the temperature to 35~55 o C, then 300~600 s -1 The stirring rate gradient of was used to start the carbon metabolism reaction and obtain a mixed system; S2, during the stable period of carbon metabolism reaction, the same volume of mixed system was discharged and transported from the closed carbon metabolism reactor, so that the ion exchanger residence time was 72~240h. At the same time, the sludge loading rate was adjusted to 1~13.33 kg TS / m by changing the sludge solid content and the ion exchanger residence time. 3 / d, the release of endogenous electron shuttles is 3.50~9.00 kg / ton TS; S3, uses PAC or FeCl3 to condition the mixed system discharged from S2 to obtain a conditioned liquid, then performs solid-liquid separation on the conditioned liquid, and then recovers the obtained filtrate to obtain a dehydrated filtrate, which is rich in small molecule organic acids, thereby completing the recovery of the small molecule organic acid carbon source.

2. The method for producing small molecule organic acids by anaerobic carbon metabolism based on ion exchange-induced selective release of endogenous electron shuttles in sludge and sludge deconstruction according to claim 1, characterized in that: The closed carbon metabolism reactor in S2 is equipped with a SCOD online monitor, a microbial metabolic conversion rate analyzer, an electrochemical activity meter and a volatile fatty acid online monitor to monitor the SCOD, microbial metabolic conversion rate of small molecule organic acids, electrochemical activity and small molecule organic acid production in the S2 process respectively. When the following conditions are not met, one or more of the methods 1, 2 and 3 are adopted. Method 1 is to increase the dosage of the ion exchanger in S1, method 2 is to extend the residence time of the ion exchanger, and method 3 is to reduce the sludge load rate until the following conditions are met: SCOD ≥ 20% of sludge solid content, electrochemical activity ≥ 0.3 mmol e - / g C, microbial metabolic conversion rate of small molecule organic acids ≥50%, and small molecule organic acid production ≥0.04 kg C / kg TS.

3. The method for producing small molecule organic acids by anaerobic carbon metabolism based on ion exchange-induced selective release of endogenous electron shuttles in sludge and sludge deconstruction according to claim 1, characterized in that: In S1, the solid content of the sludge is adjusted to 10-40 g TS / L by standing concentration or diluting with water to obtain feed sludge.

4. The method for producing small molecule organic acids by anaerobic carbon metabolism based on ion exchange-induced selective release of endogenous electron shuttles in sludge and sludge deconstruction according to claim 1, characterized in that The ion exchanger described in S1 is sodium citrate, sodium pyrophosphate or ethylenediaminetetraacetic acid.

5. The method for producing small molecule organic acids by anaerobic carbon metabolism based on ion exchange-induced selective release of endogenous electron shuttles in sludge and sludge deconstruction according to claim 1, characterized in that: When the ion exchanger described in S1 is an insoluble solid ion exchanger, the ion exchanger is activated using 0.8~1.2 mol / L HCl solution and 0.8~1.2 mol / L NaOH solution in sequence, the activation time is 3.5~6.5h, the interval between the activation of HCl solution and NaOH solution is 1.5~3.5h, the volume ratio of HCl solution to ion exchanger is 4:1~2:1, and the volume ratio of NaOH solution to ion exchanger is 4:1~2:

1.

6. The method for producing small molecule organic acids by anaerobic carbon metabolism based on ion exchange-induced selective release of endogenous electron shuttles in sludge and sludge deconstruction according to claim 5, characterized in that: The ion exchanger described in S1 is ion exchange fiber, ion exchange gel, ion exchange resin or artificial zeolite.

7. The method for producing small molecule organic acids by anaerobic carbon metabolism based on ion exchange-induced selective release of endogenous electron shuttles in sludge and sludge deconstruction according to claim 1, characterized in that: The closed carbon metabolism reactor in S1 is an integrated container of an upper cylinder and a lower cone, the diameter of the cylinder is the same as the bottom diameter of the cone, and a number of support frames distributed obliquely outward are provided at the bottom of the cylinder. An axial flow pump is installed at the mud inlet at the bottom of the closed carbon metabolism reactor, and the feed sludge is transported from bottom to top through the axial flow pump.

8. The method for producing small molecule organic acids by anaerobic carbon metabolism based on ion exchange-induced selective release of endogenous electron shuttles in sludge and sludge deconstruction according to claim 1, characterized in that: S1: Mix the feed sludge and ion exchanger evenly in a closed carbon metabolism reactor. The dosage of ion exchanger is 10~50 mmol e - / g TS, and a mixed system a is obtained; S1 mixes the feed sludge and the quinone-based electron shuttle evenly, and the dosage of the quinone-based electron shuttle is 2-10 mg / g TS to obtain a mixed system b, and then controls the temperature of the mixed system b to be 35-55 o C, react for 480-720 h to obtain inoculum sludge, which is then put into the mixed system a in the closed carbon metabolism reactor. The dry matter ratio of the inoculum sludge to the feed sludge in the mixed system a is 1:10-1:20, and the temperature is controlled at 35-55 o C, 300~600 s -1 The stirring rate gradient of was used to start the carbon metabolism reaction and obtain a mixed system.

9. An anaerobic carbon metabolism methanogenesis method based on ion exchange-induced selective release of endogenous electron shuttles in sludge and sludge deconstruction, characterized in that: Based on the method for producing small molecule organic acids by anaerobic carbon metabolism based on ion exchange-induced selective release of endogenous electron shuttles in sludge and sludge deconstruction as described in claim 1, 3, 4, 5, 6, 7 or 8, the dosage of the ion exchanger in S1 is replaced by 3-10 mmol e - / g TS was then used for S1, and the ion exchanger residence time in S2 was replaced with 240~720h and the sludge loading rate was replaced with 0.33~4 kg TS / m 3 / d later, S2 is performed, and finally S3 is replaced by collecting biogas from a closed carbon metabolism reactor, which is rich in methane, to complete the recovery of methane.

10. The anaerobic carbon metabolism methanogenesis method based on ion exchange-induced selective release of endogenous electron shuttles in sludge and sludge deconstruction according to claim 9, characterized in that: The closed carbon metabolism reactor in S2 is equipped with a SCOD online monitor, a microbial metabolic conversion rate analyzer, an electrochemical activity meter and a methane detector to monitor the SCOD, the microbial metabolic conversion rate of methane, the electrochemical activity and the methane production in the S2 process respectively. When the following conditions are not met, one or more of the methods 1, 2 and 3 are adopted. Method 1 is to increase the dosage of the ion exchanger in S1, method 2 is to extend the residence time of the ion exchanger, and method 3 is to reduce the sludge load rate until the following conditions are met: SCOD ≥ 20% of sludge solid content, electrochemical activity ≥ 0.3 mmol e - / g C, microbial metabolic conversion rate of methane ≥35%, methane production ≥50 m 3 / ton TS or 27 kg C / ton TS.

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