Hydrocarbon mixed matrix biofilm reactor and method for purifying water containing oxidative pollutants

Abstract

The present invention provides a hydrocarbon mixed matrix biofilm reactor and a method for purifying water containing oxidative pollutants, belonging to the field of water purification technology. The hydrocarbon mixed matrix biofilm reactor provided by the present invention comprises a raw water tank, a reaction tank, a water inlet pipeline system, a water outlet pipeline system, a reflux pipeline system and a gas supply system; wherein the gas supply system comprises an H2 gas cylinder, an H2 and CO2 mixed gas cylinder and a gas supply pipeline, one end of the gas supply pipeline is connected to the H2 gas cylinder and the H2 and CO2 mixed gas cylinder, and the other end of the gas supply pipeline is connected to two ports of a hollow fiber membrane assembly in the reaction tank. When the hydrocarbon mixed matrix biofilm reactor provided by the present invention is used to purify water containing oxidative pollutants, the H2 and CO2 mixed gas can be diffused synchronously and bubble-free into the biofilm through the hollow fiber membrane assembly, thereby achieving full-area control of the pH value in the biofilm.

Description

Technical Field

[0001] The invention relates to the technical field of water purification, in particular to a hydrocarbon mixed matrix biofilm reactor and a method for purifying water containing oxidative pollutants. Background Art

[0002] Oxidative pollutants (including: inorganic anions, such as nitrate, nitrite, bromate, perchlorate, etc.; (class) heavy metal ions, such as dichromate, selenate, arsenate, etc.; organic compounds, such as trichloroethylene, chloroform, etc.) are the most common pollutants in water pollution, which seriously threaten the ecological safety of water bodies and human health. The research and development of technologies for removing oxidative pollutants in water bodies has always been a hot topic for researchers at home and abroad. At present, the methods for removing oxidative pollutants in water bodies mainly include physicochemical methods and biochemical methods. Although the physicochemical method can effectively separate or remove such pollutants from water bodies, it usually has problems such as secondary pollution and high operating costs, which limits its large-scale engineering application. Although the traditional biochemical method has certain advantages over the physicochemical method in terms of environmental friendliness, it often requires the addition of an organic carbon source. If the operation and management are not appropriate, it will also lead to secondary pollution problems. Therefore, there is an urgent need to develop efficient and low-cost treatment technologies for oxidative pollutants in water bodies.

[0003] The hydrogen-based biofilm reactor (H 2 MBfR is an emerging water treatment technology based on hollow fiber membrane bubble-free diffusion of hydrogen as an electron donor, combined with microbial autotrophic reduction. It has many advantages in treating oxidative pollutants in water, such as: using clean and cheap hydrogen as an electron donor, using inorganic carbon as a carbon source, high pollutant removal efficiency, no secondary pollutants, high hydrogen utilization rate (up to 100%), etc. It is considered to be a very promising water treatment technology. However, the further development and engineering application of this technology still faces a key technical problem, that is, the use of H 2 -In the process of MBfR treating oxidative pollutants in water, protons will be consumed (e.g., formula 1 for removing nitrates), resulting in an increase in the pH value in the reactor, which will in turn reduce the removal efficiency of pollutants. At the same time, precipitates will be produced in the biofilm, such as hydroxide precipitates, carbonate precipitates or phosphate precipitates formed based on the calcium ions and magnesium ions contained in the water, thereby reducing the substrate mass transfer efficiency and causing membrane fouling.

[0004] NO 3 - +4.48H 2 +0.86CO 2 +H + =0.41N 2 +0.17C 5 H 7 O2 N+4.38H 2 O Formula 1.

[0005] H 2 - Common methods for controlling system pH in MBfR include the addition of phosphate buffer, hydrochloric acid, bicarbonate, and CO 2 etc. Recent studies have shown that adding CO 2 It is a better choice to simultaneously regulate the pH value of the system and serve as an inorganic carbon source (Jiang et al., Water Research, 2020, 184: 116177; Tang et al., Water Research, 2011. 45: 232-240; Xia et al., Chemical Engineering Journal, 2016, 290: 154-160). However, although the above method can effectively control the pH value of the mixed solution in the reactor and the outside of the biofilm, there is still a problem of too high pH value inside the biofilm. Summary of the invention

[0006] The purpose of the present invention is to provide a hydrocarbon mixed matrix biofilm reactor and a method for purifying water containing oxidative pollutants. When the hydrocarbon mixed matrix biofilm reactor provided by the present invention is used to purify water containing oxidative pollutants, the pH value in the biofilm can be controlled in the entire region, which is beneficial to ensure that the pH value in the biofilm is within the range of 1. 2 -MBfR maintains long-term high efficiency and stable operation in the process of removing oxidative pollutants.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a hydrocarbon mixed matrix biofilm reactor, comprising a raw water tank, a reaction tank, a water inlet pipeline system, a water outlet pipeline system, a reflux pipeline system and a gas supply system;

[0009] The reaction tank is provided with a hollow fiber membrane assembly; one end of the reaction tank, the water inlet pipeline system and the reflux pipeline system are connected by a three-way connection, and the other end of the reaction tank, the water outlet pipeline system and the reflux pipeline system are connected by a three-way connection; the reaction tank, the water inlet pipeline system, the water outlet pipeline system and the reflux pipeline system form a circulation loop;

[0010] The gas supply system includes H 2 Gas cylinder, H 2 With CO 2 Mixed gas cylinder and gas supply pipeline, one end of the gas supply pipeline is connected to the H 2 Gas cylinder and H 2 With CO 2The mixed gas cylinder is connected, and the other end of the gas supply pipeline is connected to the two ports of the hollow fiber membrane component in the reaction tank.

[0011] Preferably, H 2 Gas cylinder and H 2 With CO 2 An air pressure dividing valve is independently arranged on the mixed gas cylinder.

[0012] Preferably, the reaction tank is placed vertically, and the hollow fiber membrane assembly contains a plurality of hollow fiber membrane fibers.

[0013] Preferably, the hollow fiber membrane is made of hydrophobic polypropylene material; the outer diameter of the hollow fiber membrane is 200-2000 μm; and the membrane pore size of the hollow fiber membrane is 0.01-0.02 μm.

[0014] Preferably, a reflux pump is provided on the reflux pipeline system; and a water inlet pump is provided on the water inlet pipeline system.

[0015] The present invention provides a method for purifying water containing oxidative pollutants by using the hydrocarbon mixed matrix biofilm reactor described in the above technical solution, comprising the following steps:

[0016] The sludge was inoculated into the hydrocarbon mixed matrix biofilm reactor, and the raw water for acclimatization was continuously introduced into the reaction tank through the water inlet pipeline system. At the same time, the air supply system was used to provide H 2 The mixed liquid in the reaction tank is refluxed through the reflux pipeline system and merged into the water inlet pipeline system to acclimate the hydrocarbon mixed matrix biofilm reactor so that a biofilm is formed on the surface of the hollow fiber membrane assembly in the reaction tank;

[0017] The water containing oxidative pollutants is continuously introduced into the reaction tank through the water inlet pipeline system, and the gas supply system is used to provide H 2 With CO 2 The mixed gas and the mixed liquid in the reaction tank are refluxed through the reflux pipeline system and merged into the water inlet pipeline system to achieve purification of the water body containing oxidative pollutants.

[0018] Preferably, the H 2 With CO 2 H in the mixed gas 2 With CO 2 The molar ratio is (2.5~10):1.

[0019] Preferably, during the purification process, H 2 The partial pressure is 1 to 15 psig.

[0020] Preferably, during the purification process, the pH value of the mixed liquid in the reaction tank is 7-8.

[0021] Preferably, during the purification process, the flow rate of the reflux is 50 to 150 times the flow rate of the inlet water.

[0022] The present invention provides a hydrocarbon mixed matrix biofilm reactor (CO 2 / H 2 -MBfR), including a raw water tank, a reaction tank, an inlet pipe system, an outlet pipe system, a reflux pipe system and an air supply system; the reaction tank is provided with a hollow fiber membrane module; one end of the reaction tank, the inlet pipe system and the reflux pipe system are connected by a three-way connection, and the other end of the reaction tank, the outlet pipe system and the reflux pipe system are connected by a three-way connection; the reaction tank, the inlet pipe system, the outlet pipe system and the reflux pipe system form a circulation loop; the air supply system includes H 2 Gas cylinder, H 2 With CO 2 Mixed gas cylinder and gas supply pipeline, one end of the gas supply pipeline is connected to the H 2 Gas cylinder and H 2 With CO 2 The mixed gas cylinder is connected, and the other end of the gas supply pipeline is connected to the two ports of the hollow fiber membrane assembly in the reaction tank. When the hydrocarbon mixed matrix biofilm reactor provided by the present invention is used to purify water containing oxidative pollutants, H can be diffused synchronously and bubble-free into the biofilm through the hollow fiber membrane assembly. 2 With CO 2 Mixed gas can achieve full-area control of the pH value in the biofilm, avoiding the introduction of CO from the outside of the biofilm in the prior art. 2 The existing problem of only being able to control the pH value of the mixed liquid in the reactor and the outer side of the biofilm but not effectively reducing the pH value inside the biofilm leads to decreased pollutant removal efficiency and membrane fouling, which is beneficial to ensure H 2 -MBfR maintains long-term high efficiency and stable operation in the process of removing oxidative pollutants, and has good treatment efficiency for oxidative pollutants. In addition, the hydrocarbon mixed matrix biofilm reactor provided by the present invention has a simple structure and can be scaled up for engineering. 2 -The promotion and large-scale application of MBfR technology is of great significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The schematic diagram of the structure of the hydrocarbon mixed matrix biofilm reactor device in the present invention, in which 1 is a raw water tank, 2 is a water inlet pump, 3 is a reaction tank, 4 is a hollow fiber membrane assembly, 5 is a reflux pump, 6 is a water outlet pipe, 7 is a sampling port, 8 is a H 2 Gas cylinder, 9 for H 2 With CO 2 Mixed gas cylinders;

[0024] Figure 2 In Example 1, H2 and CO 2 System performance diagram of hydrocarbon mixed matrix biofilm reactor under different molar ratio conditions. DETAILED DESCRIPTION

[0025] The present invention provides a hydrocarbon mixed matrix biofilm reactor, comprising a raw water tank, a reaction tank, a water inlet pipeline system, a water outlet pipeline system, a reflux pipeline system and a gas supply system;

[0026] The reaction tank is provided with a hollow fiber membrane assembly; one end of the reaction tank, the water inlet pipeline system and the reflux pipeline system are connected by a three-way connection, and the other end of the reaction tank, the water outlet pipeline system and the reflux pipeline system are connected by a three-way connection; the reaction tank, the water inlet pipeline system, the water outlet pipeline system and the reflux pipeline system form a circulation loop;

[0027] The gas supply system includes H 2 Gas cylinder, H 2 With CO 2 Mixed gas cylinder and gas supply pipeline, one end of the gas supply pipeline is connected to the H 2 Gas cylinder and H 2 With CO 2 The mixed gas cylinder is connected, and the other end of the gas supply pipeline is connected to the two ports of the hollow fiber membrane component in the reaction tank.

[0028] In the present invention, unless otherwise specified, the required equipment or materials are commercially available products well known to those skilled in the art.

[0029] The hydrocarbon mixed matrix biofilm reactor provided by the present invention comprises a raw water tank for storing water containing oxidative pollutants. The present invention has no special restrictions on the size and material of the raw water tank, which can be selected according to actual needs.

[0030] The hydrocarbon mixed matrix biofilm reactor provided by the present invention comprises a reaction tank, an inlet pipe system, an outlet pipe system and a reflux pipe system; one end of the reaction tank, the inlet pipe system and the reflux pipe system are connected in a three-way manner; the other end of the reaction tank, the outlet pipe system and the reflux pipe system are connected in a three-way manner; the reaction tank, the inlet pipe system, the outlet pipe system and the reflux pipe system form a circulation loop.

[0031] As an embodiment of the present invention, the reaction pool is placed vertically, and a water inlet is provided at the bottom of the reaction pool, and the water inlet is connected to the water inlet pipeline system and the reflux pipeline system through a three-way connection; a water outlet is provided at the top of the reaction pool, and the water outlet is connected to the water outlet pipeline system and the reflux pipeline system through a three-way connection. As an embodiment of the present invention, openings are provided at both ends of the pool wall of the reaction pool for installing a hollow fiber membrane assembly. As an embodiment of the present invention, the reaction pool is processed from a square glass tube, and the inner wall size is 10×10 mm and the tube length is 350 mm.

[0032] In the present invention, a hollow fiber membrane assembly is provided in the reaction pool. As an embodiment of the present invention, the hollow fiber membrane assembly contains a plurality of hollow fiber membrane filaments, specifically 32 hollow fiber membrane filaments. In the present invention, the material of the hollow fiber membrane filaments is preferably a hydrophobic polypropylene material; the outer diameter of the hollow fiber membrane filaments is preferably 200 to 2000 μm, more preferably 280 μm; the membrane pore size of the hollow fiber membrane filaments is preferably 0.01 to 0.02 μm, more preferably 0.02 μm. As an embodiment of the present invention, the two ends of the hollow fiber membrane assembly are respectively bonded to the sleeve with epoxy resin glue, and then the sleeve is bonded to the opening on the pool wall of the reaction pool with epoxy resin glue to achieve the fixation of the hollow fiber membrane assembly.

[0033] As an embodiment of the present invention, the water inlet pipeline system is provided with a water inlet pump for passing the water containing oxidative pollutants into the reaction tank through the water inlet pipeline system, and the water inlet flow rate can be regulated at the same time.

[0034] As an embodiment of the present invention, a reflux pump is provided on the reflux pipeline system for refluxing the mixed liquid in the reaction tank, and the reflux rate can be adjusted to ensure that the mixed liquid in the hydrocarbon mixed matrix biofilm reactor is fully mixed.

[0035] As an embodiment of the present invention, a water outlet pipe is provided on the water outlet pipeline system, and the water outlet pipe is provided with a sampling port.

[0036] The hydrocarbon mixed matrix biofilm reactor provided by the present invention comprises a gas supply system, wherein the gas supply system comprises H 2 Gas cylinder, H 2 With CO 2 Mixed gas cylinder and gas supply pipeline, one end of the gas supply pipeline is connected to the H 2 Gas cylinder and H 2 With CO 2 The other end of the gas supply line is connected to the two ports of the hollow fiber membrane assembly in the reaction tank. As an embodiment of the present invention, the H 2 Gas cylinder and H 2With CO 2 The mixed gas cylinder is independently provided with a pressure dividing valve for regulating the gas pressure. 2 The gas cylinder can be used to acclimate the hydrocarbon mixed matrix biofilm reactor, so that a biofilm is formed on the surface of the hollow fiber membrane assembly in the reaction tank; the H 2 With CO 2 The mixed gas cylinder is used to purify water containing oxidative pollutants, among which H 2 With CO 2 The mixed gas is passed into the hollow fiber membrane module, and then H 2 With CO 2 The mixed gas diffuses into the biofilm in a bubble-free manner through the micropores on the wall of the hollow fiber membrane, achieving full-area control of the pH value in the biofilm.

[0037] The present invention provides a method for purifying water containing oxidative pollutants by using the hydrocarbon mixed matrix biofilm reactor described in the above technical solution, comprising the following steps:

[0038] The sludge was inoculated into the hydrocarbon mixed matrix biofilm reactor, and the raw water for acclimatization was continuously introduced into the reaction tank through the water inlet pipeline system. At the same time, the air supply system was used to provide H 2 The mixed liquid in the reaction tank is refluxed through the reflux pipeline system and merged into the water inlet pipeline system to acclimate the hydrocarbon mixed matrix biofilm reactor so that a biofilm is formed on the surface of the hollow fiber membrane assembly in the reaction tank;

[0039] The water containing oxidative pollutants is continuously introduced into the reaction tank through the water inlet pipeline system, and the gas supply system is used to provide H 2 With CO 2 The mixed gas and the mixed liquid in the reaction tank are refluxed through the reflux pipeline system and merged into the water inlet pipeline system to achieve purification of the water body containing oxidative pollutants.

[0040] The present invention inoculates sludge into a hydrocarbon mixed matrix biofilm reactor, continuously introduces raw water for acclimatization into the reaction tank through a water inlet pipeline system, and simultaneously uses an air supply system to provide H 2 , the mixed liquid in the reaction tank is refluxed through the reflux pipeline system and merged into the water inlet pipeline system, the hydrocarbon mixed matrix biofilm reactor is tamed, and a biofilm is formed on the surface of the hollow fiber membrane assembly in the reaction tank. The present invention first starts and tames the hydrocarbon mixed matrix biofilm reactor to form a biofilm on the surface of the hollow fiber membrane assembly in the reaction tank and ensures that the hydrocarbon mixed matrix biofilm reactor runs smoothly in the subsequent purification process.

[0041] The present invention does not specifically limit the source of the sludge, and sludge familiar to those skilled in the art can be used. In an embodiment of the present invention, taking the use of a hydrocarbon mixed matrix biofilm reactor to purify a nitrate-containing water body as an example, the sludge is preferably anoxic tank sludge from a municipal sewage treatment plant. In the present invention, the inoculation amount of the sludge is preferably 10% of the total effective volume of the hydrocarbon mixed matrix biofilm reactor. In the present invention, the raw water for acclimation is preferably supplemented with an inorganic carbon source and a buffer solution on the basis of the water body containing oxidative pollutants, so as to meet the growth of microorganisms and control the pH value of the system within a suitable range; in the present invention, the inorganic carbon source is preferably NaHCO 3 The buffer solution is preferably a phosphate buffer, specifically KH 2 PO 4 with Na 2 HPO 4 In the embodiment of the present invention, taking the use of a hydrocarbon mixed matrix biofilm reactor to purify a nitrate-containing body water as an example, the components of the acclimatization raw water preferably include: 20 mgN / L NaNO 3 , 100 mg / L NaHCO 3 , 128mg / L KH 2 PO 4 and 434 mg / L of Na 2 HPO 4 ; preferably also includes trace elements, specifically: 1 mg / L MgSO 4 7H 2 O, 80 mg / L FeSO 4 7H 2 O, 1 mg / L CaCl 2 ·2H 2 O, 0.013 mg / L ZnSO 4 7H 2 O, 0.038 mg / L H 3 BO 3 , 0.001mg / L CuCl 2 ·2H 2 O, 0.004 mg / L Na 2 MoO 4 ·2H 2 O, 0.004 mg / L MnCl 2 ·4H 2 O, 0.025 mg / L CoCl 2 6H 2 O, 0.001 mg / L NiCl 2 6H 2 O and 0.004 mg / L Na 2SeO 3 .

[0042] In the present invention, during the start-up and acclimation of the hydrocarbon mixed matrix biofilm reactor, H 2 The partial pressure is preferably 1-15 psig, more preferably 5 psig. In the present invention, during the startup and acclimation of the hydrocarbon mixed matrix biofilm reactor, the flow rate of the reflux is preferably 50-150 times the inlet flow rate, so as to achieve the purpose of the mixed liquid in the reaction tank being in a completely mixed state; the present invention preferably continuously passes the acclimation raw water into the reaction tank through the inlet pipeline system through the inlet pump, and refluxes the mixed liquid in the reaction tank through the reflux pipeline system and merges it into the inlet pipeline system through the reflux pump; in an embodiment of the present invention, the inlet pump flow rate is preferably 0.63 mL / min, and the reflux pump flow rate is preferably 80 mL / min.

[0043] In the present invention, the thickness of the biofilm is preferably 500-900 μm, more preferably 650-700 μm. After the biofilm is formed, the present invention preferably monitors the nitrate concentration in the effluent, and when the nitrate concentration in the effluent remains stable, it is considered that the start-up and acclimation of the hydrocarbon mixed matrix biofilm reactor are completed. In an embodiment of the present invention, when the nitrate concentration in the effluent remains stable for at least 5 consecutive days, it is considered that the start-up and acclimation of the hydrocarbon mixed matrix biofilm reactor are completed.

[0044] In the present invention, after the hydrocarbon mixed matrix biofilm reactor is started and acclimated, the water containing oxidative pollutants is continuously introduced into the reaction tank through the water inlet pipeline system, and the gas supply system is used to provide H 2 With CO 2 Mixed gas, the mixed liquid in the reaction tank is refluxed through the reflux pipeline system and merged into the water inlet pipeline system to achieve the purification of the water body containing oxidative pollutants. In the present invention, the oxidative pollutants in the water body containing oxidative pollutants preferably include one or more of inorganic anions, heavy metal ions and organic compounds, the inorganic anions preferably include one or more of nitrates, nitrites, bromates and perchlorates, the heavy metal ions preferably include one or more of dichromates, selenates and arsenates, and the organic compounds preferably include one or more of trichloroethylene and chloroform; in the embodiment of the present invention, it is specifically described by taking nitrate-containing water as an example. In the present invention, the concentration of nitrate in the nitrate-containing water is preferably 10 to 100 mgN / L; in the embodiment of the present invention, the concentration of nitrate in the nitrate-containing water is specifically 20 mgN / L.

[0045] In the present invention, the H 2 With CO 2 H in the mixed gas 2With CO 2 The molar ratio of H is preferably (2.5-10):1, more preferably 5.2:1; during the purification process, H 2 The partial pressure is preferably 1-15psig, more preferably 5psig. In the present invention, during the purification process, the pH value of the mixed liquid in the reaction tank is preferably 7-8, more preferably 7.4. In the present invention, during the purification process, the flow rate of the reflux is preferably 50-150 times the inlet flow rate, more preferably 120-130 times, so as to achieve the purpose of the mixed liquid in the reaction tank being in a completely mixed state; the present invention preferably uses an inlet pump to continuously pass the water containing oxidative pollutants into the reaction tank through the inlet pipeline system, and uses a reflux pump to reflux the mixed liquid in the reaction tank through the reflux pipeline system and merge it into the inlet pipeline system; in an embodiment of the present invention, the inlet pump flow rate is preferably 0.63mL / min, and the reflux pump flow rate is preferably 80mL / min.

[0046] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. 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.

[0047] Example 1

[0048] This embodiment uses a hydrocarbon mixed matrix biofilm reactor to degrade nitrate, the most typical oxidative pollutant in water. The specific steps are as follows:

[0049] (1) According to Figure 1 A hydrocarbon mixed matrix biofilm reactor is constructed, wherein the reaction pool is processed from a square glass tube, the inner wall size is 10×10 mm, the tube length is 350 mm, and both ends of the pool wall of the reaction pool are respectively provided with openings; a hollow fiber membrane assembly is arranged in the reaction pool, the hollow fiber membrane assembly contains 32 hollow fiber membrane filaments, the hollow fiber membrane filaments are made of hydrophobic polypropylene material, the inner diameter of the hollow fiber membrane filaments is 200 μm, the outer diameter is 280 μm, and the membrane pore size is 0.02 μm; both ends of the hollow fiber membrane assembly are respectively bonded to the casing with epoxy resin glue, and then the casing is bonded to the openings on the pool wall of the reaction pool with epoxy resin glue to achieve the fixation of the hollow fiber membrane assembly;

[0050] (2) Start-up and acclimatization of hydrocarbon mixed matrix biofilm reactor: 10 mL of sludge from anoxic tank of a municipal sewage treatment plant was inoculated into the reactor (the inoculation amount was 10% of the total effective volume of the reactor); the first simulated wastewater was prepared, and the components of the first simulated wastewater included: 20 mgN / L NaNO 3, 100 mg / L NaHCO 3 (as an inorganic carbon source for microbial growth), 128 mg / L KH 2 PO 4 and 434 mg / L of Na 2 HPO 4 (as a buffer solution to control the pH value of the system), 1 mg / L MgSO 4 7H 2 O, 80 mg / L FeSO 4 7H 2 O, 1 mg / L CaCl 2 ·2H 2 O, 0.013 mg / L ZnSO 4 7H 2 O, 0.038 mg / L H 3 BO 3 , 0.001mg / L CuCl 2 ·2H 2 O, 0.004 mg / L Na 2 MoO 4 ·2H 2 O, 0.004 mg / L MnCl 2 ·4H 2 O, 0.025 mg / L CoCl 2 6H 2 O, 0.001 mg / L NiCl 2 6H 2 O and 0.004 mg / L Na 2 SeO 3 (providing trace elements required for microbial growth); the first simulated wastewater enters the hydrocarbon mixed matrix biofilm reactor from the bottom of the reaction tank through the water inlet pump and the water inlet pipeline, and the water inlet pump flow rate is set to 0.63mL / min; the reflux pump is turned on, and the reflux pump flow rate is set to 80mL / min; at the same time, the gas supply system is turned on to provide high-purity hydrogen (≥99%), and the hydrogen pressure is set to 5psig; when a biofilm visible to the naked eye is formed on the surface of the hollow fiber membrane in the reactor (the thickness is specifically 700μm), the nitrate concentration in the effluent is monitored every day. When the nitrate concentration in the effluent remains stable for 5 consecutive days, it can be considered that the startup and acclimation of the hydrocarbon mixed matrix biofilm reactor are completed;

[0051] (3) Continuous operation stage:

[0052] Prepare a second simulated wastewater, the second simulated wastewater differing from the first simulated wastewater only in that it does not contain NaHCO 3 , KH 2 PO 4 and Na2 HPO 4 According to the method in step (2), the second simulated wastewater is pumped into the reactor as the wastewater to be treated for treatment, and the gas supply system provides H 2 and CO 2 Mixed gas, monitoring in H 2 and CO 2 Under different molar ratio conditions, the nitrate removal performance and system pH value changes of the hydrocarbon mixed matrix biofilm reactor when the operation reaches stability are analyzed to determine the H 2 and CO 2 The best molar ratio; wherein, in the H 2 and CO 2 When experimenting with different molar ratios, always keep H 2 The partial pressure is the same, i.e. 5.0 psig, and different CO 2 The partial pressure is used to maintain the available H in the hydrocarbon mixed matrix biofilm reactor. 2 Consistent content;

[0053] Specific settings H 2 With CO 2 The experiments were carried out with molar ratios of 10:0, 10:1, 5.2:1 and 2.5:1. The results are as follows Figure 2 shown.

[0054] With the CO 2 The decrease of partial pressure leads to the decrease of NO 3 - The concentration of -N gradually decreases from H 2 and CO 2 The molar ratio was 2.5:1, which was reduced from 7.17 mg / L to 1.00 mg / L without adding CO. 2 4.14 mg / L. 3 - -N removal rate, reducing CO 2 The input amount will increase the reactor's NO 3 - -N removal efficiency, but when H 2 With CO 2 When the molar ratio of CO is less than 5.2, the pH value of the mixed solution in the reactor will exceed 8, increasing the risk of precipitation of hardness ions (such as calcium ions and magnesium ions) in the biofilm and causing the accumulation of nitrite, which is more toxic than nitrate. 2 Excessive input will directly lead to NO 3 - -N removal effect decreased. In summary, when H 2 With CO 2 When the molar ratio is 5.2:1, NO3 - The concentration of -N is 6.19 mg / L, NO 3 - -N is kept at a high removal rate, and there is no accumulation of nitrite. At the same time, the pH value of the mixed solution in the reactor is kept at around 7.4. Combined with theoretical calculations, this molar ratio can meet the long-term growth and metabolism of hydrogen autotrophic microorganisms. 2 and inorganic carbon requirements, which can ensure that the reactor maintains long-term, efficient and stable operation during the pollutant removal process.

[0055] Comparative Example 1

[0056] After completing step (3) according to the method of Example 1, the operation mode is changed, specifically, the gas supply system is used to provide high-purity hydrogen, and the first simulated wastewater is used as the wastewater to be treated. That is, during the continuous operation stage, NaHCO 3 As an inorganic carbon source for microbial growth, KH 2 PO 4 and Na 2 HPO 4 As a buffer solution to control the pH value of the system.

[0057] The experimental results show that the use of NaHCO 3 When the operation mode was changed, NO in the reactor outlet water was 3 - The concentration of -N is 6.5mg / L, NO 3 - -N removal rate is relatively high compared with that of H 2 With CO 2 When the molar ratio was 5.2:1, there was little difference, but 0.97 mg N / L of nitrite accumulated in the effluent, and the pH value of the mixed solution in the reactor was around 8.3. After the reactor was operated for 3 months in this way, NO 3 - -N concentration increased to 8.6 mg / L, NO 3 - -N removal rate is higher than that of H 2 With CO 2 When the molar ratio was 5.2:1, the mixed gas decreased by 12%. The possible reason is that with the long-term operation of the reactor, the pH value in the biofilm cannot be effectively controlled, and the hardness ions (such as calcium ions and magnesium ions) are precipitated in the biofilm, thereby reducing the mass transfer efficiency of the substrate in the biofilm and affecting the denitrification activity.

[0058] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for purifying water containing oxidative pollutants using a hydrocarbon mixed matrix biofilm reactor, The hydrocarbon mixed matrix biofilm reactor comprises a raw water tank, a reaction tank, a water inlet pipeline system, a water outlet pipeline system, a reflux pipeline system and a gas supply system; The reaction tank is provided with a hollow fiber membrane assembly; one end of the reaction tank, the water inlet pipeline system and the reflux pipeline system are connected by a three-way connection, and the other end of the reaction tank, the water outlet pipeline system and the reflux pipeline system are connected by a three-way connection; the reaction tank, the water inlet pipeline system, the water outlet pipeline system and the reflux pipeline system form a circulation loop; The gas supply system includes an H2 gas cylinder, an H2 and CO2 mixed gas cylinder and a gas supply pipeline, one end of the gas supply pipeline is connected to the H2 gas cylinder and the H2 and CO2 mixed gas cylinder, and the other end of the gas supply pipeline is connected to two ports of the hollow fiber membrane assembly in the reaction tank; the H2 gas cylinder and the H2 and CO2 mixed gas cylinder are independently provided with a pressure dividing valve; The method comprises the following steps: Inoculating sludge into a hydrocarbon mixed matrix biofilm reactor, continuously introducing acclimatization raw water into the reaction tank through a water inlet pipeline system, and simultaneously using a gas supply system to provide H2, the mixed liquid in the reaction tank is refluxed through a reflux pipeline system and merged into the water inlet pipeline system, the hydrocarbon mixed matrix biofilm reactor is acclimatized, and a biofilm is formed on the surface of the hollow fiber membrane assembly in the reaction tank; The water containing oxidative pollutants is continuously introduced into the reaction tank through the water inlet pipeline system, and a gas supply system is used to provide a mixed gas of H2 and CO2. The mixed liquid in the reaction tank is refluxed through the reflux pipeline system and merged into the water inlet pipeline system to achieve purification of the water containing oxidative pollutants; The molar ratio of H2 to CO2 in the H2 and CO2 mixed gas is 5.2:1; During the purification process, the partial pressure of H2 is 1-5 psig, and the pH value of the mixed liquid in the reaction tank is 7-8.

2. The method according to claim 1, characterized in that The reaction pool is placed vertically, and the hollow fiber membrane component contains a plurality of hollow fiber membrane fibers.

3. The method according to claim 2, characterized in that The hollow fiber membrane is made of hydrophobic polypropylene material; the outer diameter of the hollow fiber membrane is 200-2000 μm; and the membrane pore size of the hollow fiber membrane is 0.01-0.02 μm.

4. The method according to claim 1, characterized in that The reflux pipeline system is provided with a reflux pump; the water inlet pipeline system is provided with a water inlet pump.

5. The method according to claim 1, characterized in that During the purification process, the flow rate of the reflux is 50 to 150 times the flow rate of the inlet water.

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