An experimental device for removing trichloroethylene by reinforced in-situ biological sulfidation zero-valent iron

Abstract

The application provides an experimental device for strengthening in-situ biological sulfuration of zero-valent iron to remove trichloroethylene, which comprises a sample inlet bag, a peristaltic pump, a seepage column and a post-treatment column; a point glue needle head made of stainless steel is inserted into the sample inlet bag, the outer end of the point glue needle head is connected with a luer female connector, the luer female connector is connected with a first polytetrafluoroethylene hard pipe through a first hose; the right end of the peristaltic pump is connected with the sample inlet bag, and the left end is connected with the seepage column; the upper end of the seepage column is connected with the post-treatment column; the lower end is connected with the peristaltic pump; the sidewall of the middle 30 cm of the seepage column is opened every 5 cm, and all are connected through three-way connectors; the middle of the seepage column is filled with quartz sand in 6 layers, and the surface of each layer of quartz sand is uniformly injected with domesticated bacteria liquid; xanthan gum modified zero-valent iron slurry is injected into the seepage column from multiple points on the side and bottom of the seepage column. Through the technical scheme of the application, the system error of the experimental device for removing trichloroethylene is reduced, the degradation truth of the trichloroethylene by the filling medium is restored, the problem of the separation of pre-sulfuration and experimental dechlorination is solved, the in-situ biological sulfuration dechlorination effect is improved, and the repair goal of'sulfuration and dechlorination simultaneously' is achieved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of groundwater in-situ remediation, in particular to an experimental device for removing trichloroethylene by enhanced in-situ biological sulfidation zero-valent iron. BACKGROUND

[0002] Trichloroethylene (TCE) is widely used in the industrial field of dry cleaning, degreasing and the like, and is released into the underground due to improper manufacturing process, misuse and unsafe disposal and the like, and is one of the most common organic pollutants in groundwater. Based on the analysis of a total of 791 sets of groundwater sample data in the whole country from 2008 to 2010, the detection rate of TCE in the groundwater in China is 3.79%, indicating that TCE is one of the main halogenated hydrocarbon pollutants. Zero-valent iron (ZVI) is selected as the in-situ remediation reaction medium of the groundwater due to the advantages of high reduction, low cost and small environmental disturbance. However, in the actual application, problems such as easy precipitation, aging and poor target selectivity affect the remediation effect. Sulfidation modification is proved to effectively improve the removal effect of ZVI on chlorinated hydrocarbon pollutants (especially trichloroethylene). At present, the sulfidation modification of ZVI is mainly through two ways of liquid phase synthesis and mechanical ball milling, respectively, to make the sulfur iron compound (FeSx) deposit on the surface of ZVI or uniformly distribute in the whole ZVI particle. However, the artificial pre-sulfidation of ZVI increases the cost, and the by-products generated by the liquid phase synthesis method have environmental risks, which forces us to seek a more green, economical and efficient sulfidation method.

[0003] In fact, the concentration of sulfate in a large number of chlorinated hydrocarbon contaminated sites far exceeds the limit value of groundwater class III standard, and there are rich sulfate reducing bacteria (SRB), which creates conditions for the in-situ biological sulfidation of oxidized iron minerals or ZVI. When the content of sulfate in the groundwater is sufficient, organic matter can stimulate the growth of SRB, and the respiration of SRB causes the natural existing Fe (III) oxide / hydroxide minerals in the sediment to generate reducing iron sulfide minerals (FeS and FeS2), promoting the reductive dechlorination of chlorinated alkenes. In recent years, there have been studies on the use of SRB to reduce SO4 2- The biological sulfide (S 2- , S - , Sn 2- ) obtained is used as a new sulfur source for the sulfidation modification of ZVI to pre-synthesize biological sulfidation ZVI, and the material obtained exhibits good trichloroethylene removal performance in the subsequent degradation experiment, including the trichloroethylene removal rate and selective reduction capacity similar to those of chemical sulfidation ZVI.

[0004] The patent disclosure of CN 117658339 A discloses a kind of zero-valent iron and microorganism synergistic degradation trichloroethylene and the patent disclosure of CN 116002872 B discloses a method for regulating zero-valent iron in-situ self-sulfidation and groundwater remediation, which confirms that biological sulfidation zero-valent iron has good remediation efficiency, but they are all pre-biological sulfidation of ZVI, and then dechlorination experiment is carried out, which leads to the pre-biological sulfidation of ZVI and the subsequent dechlorination experiment being separated in time and space, and the influence of groundwater environmental conditions on in-situ biological sulfidation effect cannot be reflected in actual site, which is not conducive to determining the remediation effect of biological sulfidation ZVI system under actual conditions. Moreover, in the process of in-situ remediation in actual site, the migration of materials will have a significant impact on the long-term remediation efficiency of biological sulfidation zero-valent iron. If the migration is too low, the material cannot effectively cover the pollution plume in the groundwater, and the dechlorination reaction cannot be effectively carried out. At the same time, through our previous experimental research, it is found that the removal effect of the indoor simulation device material on trichloroethylene in the trichloroethylene contaminated groundwater remediation experiment is greatly disturbed. Therefore, it is necessary to improve the existing experimental device and method, that is, to develop an experimental device for strengthening in-situ biological sulfidation zero-valent iron to remove trichloroethylene. SUMMARY

[0005] In order to make up for the shortcomings of the prior art, the present application provides an experimental device for strengthening in-situ biological sulfidation zero-valent iron to remove trichloroethylene, which reduces the systematic error of the experimental device on the removal of trichloroethylene, restores the truth of the degradation of the filling medium on trichloroethylene, solves the problem of pre-sulfidation and experimental dechlorination, improves the in-situ biological sulfidation dechlorination effect, and achieves the remediation goal of "sulfidation and dechlorination simultaneously".

[0006] The experimental device for strengthening in-situ biological sulfidation zero-valent iron to remove trichloroethylene comprises a sample injection bag, a peristaltic pump, a seepage column and a post-treatment column.

[0007] A point glue needle made of stainless steel is inserted into the sample injection bag, and the outer end of the point glue needle is connected with a luer female connector, and the luer female connector is connected with a first polytetrafluoroethylene hard pipe through a first soft pipe.

[0008] The peristaltic pump is connected with left and right ends by Viton fluororubber pump pipes, the right end is a first Viton fluororubber pump pipe, and the left end is a second Viton fluororubber pump pipe, the other end of the first Viton fluororubber pump pipe and the second Viton fluororubber pump pipe is respectively connected with a first soft and hard pipe conversion connector and a second soft and hard pipe conversion connector, the first Viton fluororubber pump pipe is connected with the other end of the first polytetrafluoroethylene hard pipe through the first soft and hard pipe conversion connector, and the second Viton fluororubber pump pipe is connected with a second polytetrafluoroethylene hard pipe through the second soft and hard pipe conversion connector.

[0009] The seepage column is a glass cylinder with a total length of 36 cm, and the upper and lower ends of the seepage column are respectively connected with an upper rotary cover and a lower rotary cover; the upper rotary cover is connected with a first three-way joint, and the first three-way joint is connected with a post-treatment column filled with activated carbon through a second hose; the lower rotary cover is connected with the other end of a second polytetrafluoroethylene hard pipe through a third hose and a combination device; the bottom and top of the seepage column are uniformly filled with 3 cm of glass beads, and the sidewall of the middle 30 cm is opened every 5 cm and connected by a second three-way joint; the middle 30 cm of the seepage column is evenly divided into 6 layers and filled with quartz sand, and 10 mL of acclimated bacteria solution is uniformly injected on the surface of each layer of quartz sand using a syringe; the xanthan gum modified zero-valent iron slurry is injected into the seepage column from multiple points on the side and bottom of the seepage column. During the loading process, N2 is continuously introduced.

[0010] As a preferred solution, the sample bottle is a round-bottom vertical biological sterile water sample collection bag with a silica gel plug.

[0011] As a preferred solution, the connection between the Luer female swivel joint, the first hose and the first polytetrafluoroethylene hard pipe is sealed and wrapped with a sealing film.

[0012] As a preferred solution, the materials of the upper rotary cover and the lower rotary cover are polytetrafluoroethylene.

[0013] As a preferred solution, the first soft and hard pipe conversion joint and the second soft and hard pipe conversion joint are both internally provided with an inverted taper joint, and the inverted taper joint is arranged at the hard interface end of the first soft and hard pipe conversion joint and the second soft and hard pipe conversion joint.

[0014] As a preferred solution, the combination device includes an outer swivel joint, a third three-way joint and an inner swivel joint, the left and right ends of the third three-way joint are respectively connected with the outer swivel joint and the inner swivel joint, the outer swivel joint is connected to the lower rotary cover through a third hose, and the inner swivel joint is connected to the second polytetrafluoroethylene hard pipe.

[0015] As a preferred solution, the acclimation method of the bacteria solution is as follows: 10 g of in-situ water medium is added to a 500 mL serum bottle, which is filled with simulated groundwater with a dissolved oxygen concentration of less than 0.5 mg / L, and 2 mL / L of sodium lactate is added as a carbon source; cultivate in a 25℃, 120 rpm shaker, and measure the SO4 2- concentration in the sample at regular intervals. It is observed that the solution becomes dark and has a pungent odor, indicating that the microorganisms have been successfully acclimated. In addition, the simulated groundwater is replaced once a week to maintain the activity of the microorganisms and ensure that they can be used in subsequent experiments.

[0016] As a preferred solution, the preparation method of the xanthan gum modified zero-valent iron slurry is: 1 L of ultrapure water and xanthan gum are added into a conical flask, and N2 is introduced into the flask to ensure that the dissolved oxygen concentration in the water is lower than 0.5 mg / L; under the condition that the mouth of the flask is sealed, a mechanical stirrer is used for high-speed stirring for 1 h until the xanthan gum is uniformly dispersed; then, 10 g of micron zero-valent iron (mZVI) is added, and the sealed stirring is continued for 1 h to ensure that the zero-valent iron is uniformly dispersed and modified, so that the uniformly dispersed xanthan gum modified zero-valent iron slurry is obtained.

[0017] As a preferred solution, the sampling bottle is internally provided with simulated groundwater containing trichloroethylene, and the simulated experiment of in-situ removal of trichloroethylene in groundwater is carried out by flowing the groundwater into the seepage column from bottom to top at a flow rate of 96.00 µL / min, which is equivalent to a groundwater flow rate of 11.01 cm / d.

[0018] The present application has the following beneficial effects compared with the prior art due to the adoption of the above technical solutions:

[0019] (1) The present application solves the problem of the separation of zero-valent iron pre-chemical sulfurization and subsequent dechlorination experiments in time and space, confirms the possibility of in-situ biological sulfurization of zero-valent iron in groundwater, and reduces the economic cost of sulfurization technology.

[0020] (2) The round-bottom vertical biological sterile water sample collection bag, the polytetrafluoroethylene hard pipe and the Viton fluororubber pump pipe, and the glass seepage column used in the present application can all reduce the adsorption of pollutants trichloroethylene by the device and reduce the influence of the experimental device on the experimental results.

[0021] (3) The detailed connection method of the experimental device of the present application can solve the problem of air and water leakage at the interface caused by the inconsistency of the inner diameters of the pipelines.

[0022] (4) The experimental device and method for simulating in-situ biological sulfurization of zero-valent iron of the present application can realize the long-term effectiveness and stability of removing trichloroethylene in groundwater.

[0023] (5) The device of the present application has simple operation steps, strong practicality, low cost, and is convenient for laboratories to carry out simulation of in-situ treatment technology for groundwater pollution in actual sites.

[0024] The additional aspects and advantages of the present application will become apparent from the following description part, or be understood through the practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0025] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0026] Figure 1 It is a schematic diagram of the indoor experimental device of the present application;

[0027] Figure 2 The structural diagram of the combined device of the present application;

[0028] Figure 3 The distribution of mZVI in different systems of application example 2;

[0029] Figure 4 The SEM image of the 2 μm mZVI sample of application example 2 as received;

[0030] Figure 5 The SEM image of the mZVI sample of different layers after reaction in different systems of application example 2;

[0031] Figure 6 The XRD image of the mZVI sample of different layers after reaction in different systems of application example 2;

[0032] Figure 7 The characteristic graph of the trichloroethylene content of effluent water changing with time in different systems of application example 2. DETAILED DESCRIPTION

[0033] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the present application will be further described in detail below in combination with the drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0034] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, however, the present application can also be implemented in other different manners from those described herein, therefore, the protection scope of the present application is not limited by the specific embodiments disclosed below.

[0035] The following will be described in combination with Figures 1 to 7 The experimental device for removing trichloroethylene by reinforced in-situ biological sulfuration of zero-valent iron is specifically described.

[0036] As Figure 1 , Figure 2 shown, the present application proposes an experimental device for removing trichloroethylene by reinforced in-situ biological sulfuration of zero-valent iron, which comprises a sample injection bag 1, a peristaltic pump 2, a seepage column 3 and a post-treatment column 4.

[0037] A stainless steel dispensing needle 1.1 is inserted into the sample injection bag 1, the outer end of the dispensing needle 1.1 is connected with a luer female connector 1.2, the luer female connector 1.2 is connected with a first polytetrafluoroethylene hard pipe 1.4 through a first hose 1.3, and the luer female connector 1.2, the first hose 1.3 and the first polytetrafluoroethylene hard pipe 1.4 are sealed and wound at the connection position by sealing film. The sample injection bottle 1 is a round-bottom vertical biological sterile water sample collection bag with a silica gel plug.

[0038] The peristaltic pump 2 uses Viton fluororubber pump tubing to connect the left and right ends. The right end is the first Viton fluororubber pump tubing 2.1, and the left end is the second Viton fluororubber pump tubing 2.2. The other ends of the first Viton fluororubber pump tubing 2.1 and the second Viton fluororubber pump tubing 2.2 are respectively connected to the first flexible-hard tube adapter 2.3 and the second flexible-hard tube adapter 2.4. The first Viton fluororubber pump tubing 2.1 is connected to the other end of the first polytetrafluoroethylene rigid tube 1.4 through the first flexible-hard tube adapter 2.3, and the second Viton fluororubber pump tubing 2.2 is connected to the second polytetrafluoroethylene rigid tube 2.5 through the second flexible-hard tube adapter 2.4. Both the first flexible-hard tube adapter 2.3 and the second flexible-hard tube adapter 2.4 have built-in inverted tapered joints, which are located at the rigid interface ends of the first flexible-hard tube adapter 2.3 and the second flexible-hard tube adapter 2.4.

[0039] The seepage column 3 is a glass cylinder with a total length of 36 cm. The upper and lower ends of the seepage column 3 are connected to an upper cap 3.1 and a lower cap 3.2, respectively. The upper cap 3.1 is connected to a first tee connector 3.4, which connects to the post-treatment column 4, which is filled with activated carbon, via a second flexible hose 3.5. The lower cap 3.2 connects to the other end of a second PTFE rigid tube 2.5 via a third flexible hose 3.7 and a combination device 3.3. The bottom and top of the seepage column 3 are uniformly filled with 3 cm glass beads, and the middle 30 cm sidewalls are spaced 5 beads apart. The opening is cm and connected using a second tee connector 3.6 for convenient subsequent operation; the combined device 3.3 includes an external tee connector 3.8, a third tee connector 3.9 and an internal tee connector 3.10. The left and right ends of the third tee connector 3.9 are connected to the external tee connector 3.8 and the internal tee connector 3.10 respectively. The external tee connector 3.8 is connected to the lower cap 3.2 through the third flexible hose 3.7, and the internal tee connector 3.10 is connected to the second PTFE rigid tube 2.5.

[0040] The middle 30 cm of the seepage column was filled with six layers of quartz sand in equal proportions. Using a syringe, 10 mL of acclimation bacterial solution was evenly injected onto the surface of each layer of quartz sand. Xanthan gum-modified zero-valent iron slurry was injected into the seepage column through multiple circulatory points from the sides and bottom. During the filling process, N2 was continuously introduced to maintain an anaerobic environment.

[0041] The acclimatization method for the bacterial culture was as follows: 10 g of in-situ aqueous medium was added to a 500 mL serum bottle, and the bottle was filled with simulated groundwater (Table 1) with a dissolved oxygen concentration of less than 0.5 mg / L. 2 mL / L of sodium lactate was added as a carbon source. The culture was carried out in a shaker at 25℃ and 120 rpm, and the SO4 content in the samples was measured periodically. 2- The concentration was measured, and the solution turned noticeably darker and developed a pungent odor, indicating successful microbial acclimatization. Furthermore, the simulated groundwater was replaced weekly to maintain microbial activity and ensure its availability for subsequent experiments.

[0042] Table 1 Composition of simulated groundwater

[0043]

[0044] The preparation method of the xanthan gum modified zero-valent iron slurry is as follows: 1 L of ultrapure water and xanthan gum are added to a conical flask, and N2 is introduced into the flask to ensure that the dissolved oxygen concentration in the water is less than 0.5 mg / L; under the condition that the mouth of the flask is sealed, a mechanical stirrer is used for high-speed stirring for 1 h until the xanthan gum is completely dissolved; then, 10 g of micron zero-valent iron is added, and the stirring is continued for 1 h under the condition of sealing to ensure that the zero-valent iron is uniformly dispersed and modified, so that the uniformly dispersed xanthan gum modified zero-valent iron slurry is obtained.

[0045] Experiment of in-situ removal of trichloroethylene from groundwater: simulated groundwater containing 10 mg / L of trichloroethylene is continuously introduced into the above-mentioned simulated column from bottom to top at a flow rate of 96.00 µL / min, which is equivalent to a groundwater flow rate of 11.01 cm / d, and is injected into the seepage column.

[0046] Application Example 1:

[0047] The above-mentioned self-improved experimental device is used to explore the influence of the indoor experimental simulation device on the adsorption of trichloroethylene. The device composed of a common material (soft silica gel) pipe and a PVC seepage column is used as a control group, and the improved experimental device composed of a hard pipe made of polytetrafluoroethylene and a glass seepage column is used as an experimental group. The quartz sand treated by soaking in hydrochloric acid and rinsing with ultrapure water is filled in the seepage column of each device. Simulated groundwater containing trichloroethylene is continuously introduced into the above-mentioned simulated column from bottom to top at a flow rate of 96.00 µL / min, which is equivalent to a groundwater flow rate of 11.01 cm / d, and is injected into the seepage column. The remaining experimental operation steps are consistent. The original concentration of trichloroethylene C0, the concentration at the inlet end of the seepage column C1, and the concentration at the outlet end of the seepage column C2 are obtained. The adsorption rate of the inlet pipe in the two experimental devices of the present application and the adsorption amount of the simulated reaction column in the two experimental devices of the present application are shown in Table 2.

[0048] According to Table 2, compared with the soft silica gel pipe in the experimental device of the control group, the hard pipe made of polytetrafluoroethylene in the experimental device of the experimental group has a smaller adsorption rate of trichloroethylene. Compared with the PVC seepage column in the experimental device of the control group, the glass seepage column in the experimental device of the experimental group has a smaller adsorption amount of trichloroethylene. Therefore, it is very necessary to use the hard pipe made of polytetrafluoroethylene and the glass seepage column to assemble the experimental device.

[0049] Table 2 Adsorption rate data of trichloroethylene in two experimental devices

[0050]

[0051] Application Example 2:

[0052] The above experimental device and in-situ biological sulfidation system construction method are used to simulate in-situ remediation of trichloroethylene contaminated groundwater. First, the medium in Table 1 is configured for microbial domestication, and 10 mL of domesticated microbial liquid is uniformly injected into each layer of quartz sand, second, non-xanthan gum modified mZVI (BS2) with a particle size of 2 μm is set as a control group, and a manual syringe is used to inject from the side opening; 3 g of xanthan gum modified mZVI (XG-BS2) with a particle size of 2 μm is used as an experimental group, and 2 L of xanthan gum modified zero-valent iron slurry is injected into the infiltration column in a multi-point circulation mode; the above infiltration column is continuously fed from bottom to top with simulated groundwater containing 10 mg / L of trichloroethylene, and the flow rate is 96.00 μL / min, which is equivalent to a groundwater flow rate of 11.01 cm / d, and the remaining experimental operation steps are consistent.

[0053] The distribution of mZVI in the BS2 and XG-BS2 groups obtained by the present application is shown in Figure 3 . Since it is not modified by xanthan gum, the distribution of mZVI in BS2 is uneven, mainly concentrated near the injection port. In contrast, the mZVI in the XG-BS2 group has enhanced suspension stability and mobility due to modification, and is more evenly distributed in the infiltration column.

[0054] The SEM image of the original 2 μm mZVI sample used in the experiment is shown in Figure 4 ; the SEM images of mZVI samples in different layers of the BS2 and XG-BS2 groups obtained by the present application after reaction are shown in Figure 5 , wherein BS2-U is the upper layer of the BS2 group, BS2-M is the middle layer of the BS2 group, BS2-B is the lower layer of the BS2 group, and similarly, XG-BS2-U, XG-BS2-M, and XG-BS2-B have the same meaning. It can be seen from Figure 4 and Figure 5 that the surface of the iron particles in the BS2 and XG-BS2 groups forms a clear sheet structure, indicating that biological sulfidation has occurred on the surface of these particles, and a uniform iron sulfide deposition layer has been formed. The XRD images of mZVI samples in different layers of the BS2 and XG-BS2 groups obtained by the present application after reaction are shown in Figure 6 . It is observed that after the reaction is completed, ferrous sulfide (FeS; 205 cm -1 ), goethite (γ-FeOOH; 252 cm -1 ), and pyrite (FeS2; 377 cm -1 ) are generally generated on the surface of the iron material in the BS2 and XG-BS2 groups, again proving the realization of in-situ biological sulfidation of zero-valent iron.

[0055] The obtained BS2 and XG-BS2 system effluent trichloroethylene content-time change diagram is as shown in Figure 7 In the initial stage (0~15 d) of the seepage column operation, the trichloroethylene concentration of each group decreases with time. The BS2 group decreases rapidly, and the trichloroethylene concentration decreases to the minimum on the 8th day, C / C0 is about 0.0, and the effluent trichloroethylene concentration starts to gradually increase after about 14 days; the trichloroethylene concentration of the XG-BS2 group decreases to the minimum on the 10th day, C / C0 is about 0.2, and the effluent trichloroethylene concentration starts to gradually increase after about 40 days, which shows that the method can prolong the reaction life of the system and successfully achieve the goal of “sulfurization and dechlorination simultaneously”.

[0056] In the description of the present application, the term "a plurality of" refers to two or more, unless otherwise explicitly limited, and the terms "upper", "lower", etc. indicate the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application; the terms "connection", "installation", "fixation" and the like should be understood broadly, for example, "connection" can be fixed connection, or detachable connection, or integral connection; can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0057] In the description of the present application, the terms "one embodiment", "some embodiments", "a specific embodiment" and the like mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0058] The above is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An experimental apparatus for enhancing in-situ biological sulfidation of zero-valent iron to remove trichloroethylene, characterized in that, Includes a sample bag (1), a peristaltic pump (2), a percolation column (3), and a post-treatment column (4); The sample bag (1) is filled with a stainless steel dispensing needle (1.1). The outer end of the dispensing needle (1.1) is connected to a Luer internal screw connector (1.2). The Luer internal screw connector (1.2) is connected to a first polytetrafluoroethylene rigid tube (1.4) through a first flexible tube (1.3). The peristaltic pump (2) is connected to the left and right ends by Viton fluororubber pump tubes. The right end is the first Viton fluororubber pump tube (2.1), and the left end is the second Viton fluororubber pump tube (2.2). The other ends of the first Viton fluororubber pump tube (2.1) and the second Viton fluororubber pump tube (2.2) are respectively connected to the first soft-hard tube conversion joint (2.3) and the second soft-hard tube conversion joint (2.4). The first Viton fluororubber pump tube (2.1) is connected to the other end of the first polytetrafluoroethylene rigid tube (1.4) through the first soft-hard tube conversion joint (2.3), and the second Viton fluororubber pump tube (2.2) is connected to the second polytetrafluoroethylene rigid tube (2.5) through the second soft-hard tube conversion joint (2.4). The seepage column (3) is a glass cylinder with a total length of 36 cm. The upper and lower ends of the seepage column (3) are connected to an upper cap (3.1) and a lower cap (3.2), respectively. The upper cap (3.1) is connected to a first tee connector (3.4), which is connected to a post-treatment column (4) filled with activated carbon via a second flexible hose (3.5). The lower cap (3.2) is connected to the other end of a second polytetrafluoroethylene rigid pipe (2.5) via a third flexible hose (3.7) and a combined device (3.3). The bottom and top of the seepage column (3) are uniformly filled with 3 cm glass beads, and the middle 30 cm sidewall has openings every 5 cm, all connected using second tee connectors (3.6). The middle 30 cm sidewall of the seepage column (3) is filled with 3 cm glass beads. Quartz sand was filled in 6 layers on average. 10 mL of acclimatization solution was injected evenly into the surface of each layer of quartz sand using a syringe. Xanthan gum modified zero-valent iron slurry was injected into the percolation column (3) from multiple points on the side and bottom. During the filling process, N2 was continuously introduced to maintain the anaerobic environment.

2. The experimental apparatus for enhanced in-situ biological sulfidation of zero-valent iron to remove trichloroethylene according to claim 1, characterized in that... The sample bag (1) is a round-bottomed vertical biological sterile water sample collection bag with a silicone stopper.

3. The experimental apparatus for enhanced in-situ biological sulfidation of zero-valent iron to remove trichloroethylene according to claim 1, characterized in that... The upper cap (3.1) and the lower cap (3.2) are made of polytetrafluoroethylene.

4. The experimental apparatus for enhanced in-situ biological sulfidation of zero-valent iron to remove trichloroethylene according to claim 1, characterized in that... The first soft-hard pipe conversion connector (2.3) and the second soft-hard pipe conversion connector (2.4) both have built-in inverted tapered connectors, which are located at the hard interface end of the first soft-hard pipe conversion connector (2.3) and the second soft-hard pipe conversion connector (2.4).

5. The experimental apparatus for enhanced in-situ biological sulfidation of zero-valent iron to remove trichloroethylene according to claim 1, characterized in that... The combined device (3.3) includes an external rotating connector (3.8), a third tee connector (3.9), and an internal rotating connector (3.10). The left and right ends of the third tee connector (3.9) are connected to the external rotating connector (3.8) and the internal rotating connector (3.10) respectively. The external rotating connector (3.8) is connected to the lower cap (3.2) through the third flexible hose (3.7), and the internal rotating connector (3.10) is connected to the second polytetrafluoroethylene rigid tube (2.5).

6. The experimental apparatus for enhanced in-situ biological sulfidation of zero-valent iron to remove trichloroethylene according to claim 1, characterized in that... The acclimatization method for the bacterial culture is as follows: 10 g of in-situ aqueous medium is added to a 500 mL serum bottle, and the bottle is filled with simulated groundwater with a dissolved oxygen concentration of less than 0.5 mg / L. 2 mL / L of sodium lactate is added as a carbon source. The culture is carried out in a shaker at 25℃ and 120 rpm, and the SO4 content in the sample is measured periodically. 2- The concentration was adjusted, and the solution turned noticeably darker and developed a pungent odor, indicating successful microbial domestication.

7. The experimental apparatus for enhanced in-situ biological sulfidation of zero-valent iron to remove trichloroethylene according to claim 1, characterized in that... The preparation method of the xanthan gum modified zero-valent iron slurry is as follows: 1 L of ultrapure water and xanthan gum are added to an Erlenmeyer flask, and N2 is introduced into the flask to ensure that the dissolved oxygen concentration in the water is below 0.5 mg / L; while keeping the flask mouth sealed, the mixture is stirred at high speed with a mechanical stirrer for 1 h until the xanthan gum is completely dissolved; then, 10 g of micron-sized zero-valent iron is added, and the mixture is stirred for another 1 h in a sealed manner to obtain the xanthan gum modified zero-valent iron slurry.

8. The experimental apparatus for enhanced in-situ biological sulfidation of zero-valent iron to remove trichloroethylene according to claim 2, characterized in that... The sample bag (1) contains simulated groundwater containing trichloroethylene, and flows into the seepage column from bottom to top at a flow rate of 96.00 µL / min, which is equivalent to a groundwater flow rate of 11.01 cm / d, to carry out a simulated experiment of in-situ removal of trichloroethylene from groundwater.

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