CN111484145B - Membrane pollution prevention membrane bioreactor - Google Patents

Abstract

The invention discloses a membrane bioreactor capable of preventing membrane pollution, which comprises a water inlet pump, a water outlet pump, an anode conductive film, a resistor and a cathode activated carbon felt, wherein the water inlet pump is connected to the lower end of a wastewater pond, the anode conductive film is arranged in the wastewater pond, the anode conductive film is connected with the water outlet pump, the cathode activated carbon felt is connected with the anode conductive film in series through the resistor, the cathode activated carbon felt is horizontally placed on the water surface in the wastewater pond, and the anode conductive film is vertically placed in wastewater in the wastewater pond. The membrane bioreactor utilizes a bioelectrochemical system to improve the degradation rate of organic matters on the surface of a membrane material, the highest removal efficiency of COD (chemical oxygen demand) of organic wastewater reaches 91.7 percent, and the removal efficiency of refractory organic matters reaches 45 percent; meanwhile, the granular or viscous organic matters blocked on the surface and in the pores of the membrane are subjected to in-situ degradation, so that the membrane pollution is effectively inhibited, the cleaning cost of the membrane component is reduced, and the condition of membrane damage is avoided.

Description

A membrane bioreactor for preventing membrane fouling

technical field

The invention relates to a membrane bioreactor, more specifically, to an anti-membrane fouling membrane bioreactor.

Background technique

Membrane Bioreactor (MBR) is an important type of wastewater treatment technology and is widely used in the treatment of high-concentration organic wastewater. The problem of membrane fouling occurs, and the transmembrane pressure difference increases after membrane fouling, which not only reduces the membrane flux, but also easily causes membrane damage, thus restricting the development and promotion of MBR technology. At present, the problem of membrane fouling is generally solved by cleaning the membrane modules manually or mechanically, which has low work efficiency, incomplete solution to the pollution problem, and high cleaning costs. The problem still exists in the existing MBR technology is that it is difficult to decompose and mineralize the organic matter with large molecular weight and stable structure in the process of high-load organic pollution wastewater treatment.

Contents of the invention

Purpose of the invention: The purpose of the invention is to provide an anti-membrane fouling membrane bioreactor capable of decomposing organic matter without producing membrane fouling.

Technical solution: A membrane bioreactor for preventing membrane fouling according to the present invention, comprising an inlet pump, an outlet pump, an anode conductive film, a resistor and a cathode activated carbon felt, the inlet pump is connected to the lower end of the waste water pool, and the anode conductive film is placed in the waste water In the pool, the anode conductive film is connected to the outlet pump, the cathode activated carbon felt is connected in series with the anode conductive film through a resistor, the cathode activated carbon felt is placed flat on the water surface in the waste water pool, and the anode conductive film is placed vertically in the waste water in the waste water pool middle.

Among them, a pressure gauge is connected between the anode conductive film and the outlet pump; the cathode activated carbon felt is composed of a porous activated carbon felt conductive layer and a supporting layer, and the supporting layer is located in the middle of the two porous activated carbon felt conductive layers and fixed with titanium wire The thickness of porous activated carbon felt is 3mm~10mm, and the supporting layer is metal mesh; the anode conductive film is composed of liner, flow guide cloth, base film layer and hydrophilic conductive coating, flow guide cloth, base film layer and hydrophilic conductive coating The conductive coating is symmetrically covered on the lining board layer by layer; the guide cloth is made of hydrophilic non-woven fabric; the hydrophilic conductive coating is a polymer coating material with conductive properties; the coating contains graphene, carbon fiber and other components It is conducive to the enrichment of electrochemically active microorganisms, and the hydrophilic properties of the coating are conducive to the degradation of organic matter by electrochemically active microorganisms and the transfer of extracellular electrons; the basement membrane layer is a permeable supporting basement membrane; the conductive polymer composite material is composed of pyrrole , graphene, carbon fiber, and metal oxide powder; the conductive base film is polytetrafluoroethylene base film soaked in sodium anthraquinone disulfonate solution; the resistor is a fixed value resistor or a variable resistor of 10Ω~10000Ω .

Working principle: In the present invention, the bioelectrochemical negative and positive electrodes form an electric field locally, so that a large amount of organic matter with ionic groups in the organic wastewater forms charged bodies such as particles, colloids, and bacterial micelles. Under the action of the electric field force, the charged particles 1. The colloid moves to the two poles. Through the regulation of the external resistance, the potential difference, redox potential and redox reaction rate of the positive and negative poles in the MBR are controlled. When the resistance value is high, a large potential difference is formed between the membrane material anode and the activated carbon felt cathode. , the surface of the membrane material and its interior are at a lower electrode potential, and some refractory organics undergo electrode half-reactions at this electrode potential, releasing protons and electrons, while in the porous activated carbon felt cathode, oxygen molecules serve as the final electron acceptor , cathodic half-reaction occurs with electrons and protons; when the external resistance value is lowered, the amount of electronic charge transferred from the bioelectrochemical anode to the cathode increases significantly, and the directional flow of electrons promotes the continuous degradation of the organic substrate at the anode, and the degradation rate of organic matter increases. The particulate or viscous organic matter on the membrane surface and pores can be degraded in situ, thereby inhibiting membrane fouling.

Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. The bioelectrochemical system is used to increase the degradation rate of organic matter on the surface of the membrane material, and the COD removal efficiency for organic wastewater reaches up to 91.7%. 2. In-situ degradation of granular or viscous organic matter blocked on the membrane surface and pores, effectively inhibiting membrane fouling and reducing the cleaning cost of membrane modules; 3. Avoiding membrane damage.

Description of drawings

Fig. 1 is a device schematic diagram of the present invention;

Fig. 2 is a schematic diagram of the structure of the anode conductive film;

Figure 3 is a schematic diagram of the reaction on the anode conductive film.

Detailed ways

As shown in Figure 1, the anti-membrane fouling membrane bioreactor includes an inlet pump 1, an outlet pump 2, an anode conductive film 4, a resistor 5 and a cathode activated carbon felt 6, the inlet pump 1 is connected to the lower end of the waste water pool, and the anode conductive film 4 Placed in a waste water pool, the anode conductive film 4 is connected to the water outlet pump 2, a pressure gauge 3 is connected between the anode conductive film 4 and the water outlet pump 2, the cathode activated carbon felt 6 is connected in series with the anode conductive film 4 through a resistor 5, and the resistor 5 is a variable resistor of 10Ω~1000Ω, the cathode activated carbon felt 6 is placed flat on the water surface in the waste water pool, the anode conductive film 4 is stacked in rows and vertically placed in the waste water in the waste water pool, and the cathode activated carbon felt 6 is formed by Porous activated carbon felt conductive layer and titanium mesh, titanium mesh is located in the middle of two layers of porous activated carbon felt conductive layer and fixed by titanium wire, porous activated carbon felt thickness is 6mm, as shown in Figure 2, the anode conductive film 4 is composed of a lining plate 41 , diversion cloth 42, base film layer 43 and hydrophilic conductive coating 44, diversion cloth 42, base film layer 43 and hydrophilic conductive coating 44 are symmetrically covered on liner plate 41 layer by layer, and diversion cloth 42 It is a hydrophilic non-woven fabric material, the hydrophilic conductive coating 44 is a polymer coating material with conductive properties, and the base film layer 43 is a permeable supporting base film, and the hydrophilic conductive coating 44 is loaded on the base film layer The preparation process of 43 is: first immerse the conductive base film polytetrafluoroethylene base film in the ultrasonic solution of sodium anthraquinone disulfonate for 10 minutes, then dry it for use, dissolve pyrrole with ethanol aqueous solution, and mix graphene, carbon fiber, metal oxide, etc. powder to obtain a composite material; immerse the polytetrafluoroethylene base film with sodium anthraquinone disulfonate into the composite material for surface polymerization and adsorption, then take it out, wash it with pure water, and dry it in the air.

The artificially prepared organic wastewater is used as the treatment object, and the specific composition is that each 1L solution contains: 400 mg glucose, 330 mg NaCl, 134 mg NH ₄ Cl, 33 mg NaH ₂ PO ₄ , 18 mg Na ₂ HPO ₄ , 340 mg NaHCO ₃ , 15 mg MgSO ₄ •7H ₂ O, 2 mg ZnSO ₄ •7H ₂ O, 2.2 mg MnSO ₄ •H ₂ O, 1 mg FeSO ₄ , 0.24 mg CoCl ₂ •6H ₂ O, 15 mg CaCl ₂ and 1.17 mg ( NH ₄ ) ₆ Mo ₇ O ₂₄ •4H ₂ O, the refractory organic matter is 50 mg/L acenaphthene and 50 mg/L pyrene in polycyclic aromatic hydrocarbons. When working, the water inlet pump 1 pumps the waste water into the waste water tank, and the high-concentration organic waste water is fully degraded by the activated sludge flocs or bacterial micelles, and the refractory organic matter is decomposed and mineralized by electrochemically active microorganisms on the surface of the membrane material to be effectively Removal, negative pressure is formed by the water outlet pump 2 to draw out waste water from the inside of the pool to the outside of the pool, the waste water is filtered through the anode conductive membrane 4, and filtered out from the water outlet 47, so that the activated sludge can be retained. The working process on the anode conductive membrane 4 is shown in Figure 3. The granular or viscous organic matter 46 that blocks the pores of the membrane in traditional MBR membrane fouling is utilized by the electrochemically active microorganisms 45 enriched on the conductive membrane material, and the following anode semi- reaction:

organic matter + H ₂ O → CO ₂ + H ⁺ + e ^-

The organic matter is degraded and eventually produces CO ₂ , hydrogen ions H ⁺ and electrons e ^- , and the electrons are transferred to the cathode activated carbon felt 6 through the wire connected to the anode conductive film 4 , and electric energy is generated when the electrons pass through the resistor 5 . In the initial stage of operation, the external circuit is disconnected, and the potential difference between the two poles is monitored. When the potential difference reaches more than 400mV, it indicates that the anode is enriched by electrochemically active microorganisms, and the external circuit is connected and a resistor is inserted.

By adjusting the external resistance value, the potential difference between the bioelectrochemical two electrodes can be changed, and the redox potential on the anode conductive film 4 can also be controlled. When the resistance value of the resistor 5 is 500Ω and 1000Ω, the anti-membrane fouling membrane bioreactor has a good degradation efficiency for the organic matter in the wastewater, especially the refractory pollutants, and the unit flux of the anode conductive film 4 is 1000 L/ (h•m ² ), the COD removal efficiency for organic wastewater can reach up to 91.7%, and the removal of refractory organic polycyclic aromatic hydrocarbons can reach 37%~45%. , the power generation performance of the bioelectrochemical system can reach up to 500 mV. The anode conductive membrane 4 degrades the particulate and dissolved organic matter on the surface of the membrane module, prevents the clogging and fouling of membrane fibers, and greatly delays the transmembrane pressure difference. When the hydraulic retention time is 4 days, it takes 60 days for the transmembrane pressure difference to reach 40 kPa, and the effective working time is much higher than that of the MBR using the traditional fiber membrane.

Claims (8)

1. The membrane bioreactor for preventing membrane pollution is characterized by comprising a water inlet pump (1), a water outlet pump (2), an anode conducting film (4), a resistor (5) and a cathode activated carbon felt (6), wherein the water inlet pump (1) is connected to the lower end of a wastewater pool, the anode conducting film (4) is arranged in the wastewater pool, the anode conducting film (4) is connected with the water outlet pump (2), the cathode activated carbon felt (6) is communicated with the anode conducting film (4) through the resistor (5) to form an external current loop, the cathode activated carbon felt (6) is horizontally arranged on the water surface in the wastewater pool, and the anode conducting film (4) is vertically arranged in wastewater in the wastewater pool; the anode conductive film (4) consists of a lining plate (41), a flow guide cloth (42), a base film layer (43) and a hydrophilic conductive coating (44), wherein the flow guide cloth (42), the base film layer (43) and the hydrophilic conductive coating (44) are symmetrically covered on the lining plate (41) layer by layer; controlling the potential difference, the oxidation-reduction potential and the oxidation-reduction reaction rate of the anode and the cathode of the MBR by regulating and controlling an external resistor, wherein when the resistance value is high, a larger potential difference is formed between the anode of the membrane material and the cathode of the activated carbon felt, the surface and the interior of the membrane material are at a lower electrode potential, some organic matters which are difficult to degrade are subjected to electrode half-reaction at the electrode potential to release protons and electrons, and in the porous activated carbon felt cathode, oxygen molecules are used as a final electron acceptor and are subjected to cathode half-reaction with the electrons and the protons; when the external resistance value is reduced, the quantity of the electric charge of the electrons transferred from the bioelectrochemistry anode to the cathode is greatly increased, the directional flow of the electrons promotes the continuous degradation of the organic substrate of the anode, the degradation rate of the organic matter is improved, and the granular or viscous organic matter blocked on the surface and in the pores of the membrane is degraded in situ, so that the membrane pollution is inhibited; the hydrophilic conductive coating (44) is loaded on the base membrane layer (43) through the preparation process: firstly, immersing a polytetrafluoroethylene-based film of a conductive base film into an anthraquinone disulfonic acid sodium solution, performing ultrasonic treatment, drying for later use, dissolving pyrrole in an ethanol water solution, and mixing with graphene, carbon fiber and metal oxide powder to obtain a composite material; soaking the polytetrafluoroethylene-based membrane with the anthraquinone disulfonic acid sodium into the composite material for surface polymerization and adsorption, taking out, cleaning with pure water, and airing.

2. The membrane bioreactor for preventing membrane pollution according to claim 1, wherein a pressure gauge (3) is connected between the anode conductive membrane (4) and the water outlet pump (2).

3. The membrane bioreactor for preventing membrane pollution, according to claim 1, wherein said cathode activated carbon felt (6) is composed of a porous activated carbon felt conductive layer and a supporting layer, said supporting layer is located between two porous activated carbon felt conductive layers and is fixed by titanium wire.

4. The membrane bioreactor for preventing membrane pollution according to claim 3, wherein the thickness of the porous activated carbon felt conductive layer is 3 mm-10 mm, and the supporting layer is a metal mesh.

5. The membrane bioreactor for preventing membrane pollution according to claim 4, wherein the flow guide cloth (42) is made of hydrophilic non-woven fabric, and the hydrophilic conductive coating (44) is a polymer coating material with conductive property.

6. The membrane bioreactor for preventing membrane fouling according to claim 4, characterized in that the base membrane layer (43) is a supporting base membrane with permeability.

7. The membrane bioreactor for preventing membrane pollution, according to claim 5, wherein said polymer coating material is made by mixing pyrrole, graphene, carbon fiber, metal oxide powder.

8. The membrane bioreactor for preventing membrane pollution according to claim 1, wherein the resistor (5) is a constant value resistor or a variable resistor of 10 Ω -10000 Ω.

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