CN111186905A

CN111186905A - Membrane biological reduction reactor and process with hydrogen as electron donor

Info

Publication number: CN111186905A
Application number: CN201910307030.XA
Authority: CN
Inventors: 宁迪; 唐宁宁; 牛飞虎; 袁蔚文; 钱媛媛
Original assignee: Mcwong Environmental Technology Co ltd
Current assignee: Mcwong Environmental Technology Co ltd
Priority date: 2019-04-17
Filing date: 2019-04-17
Publication date: 2020-05-22

Abstract

A membrane biological reduction reactor and process with hydrogen as electron donor, characterized by that there are central core tube and inner core in the container body, there are hollow fiber, fibrous assembly on the inner core, the upper end cap has air inlets, the lower end cap has water inlets, air outlets, there is a perforated pipe in the container body to connect with water outlet, its process is that untreated water enters the inner core from the water inlet through the central core tube, flow radially outwards and contact with the external surface of hollow fiber in a large scale, degrade, discharge from the water outlet after metabolizing the pollutant in the water through the fibrous assembly; meanwhile, gas enters from the gas inlet, flows through the hollow fiber inner core pipelines, is discharged from the gas outlet, and the gas entering the inner cavity is used for the growth of microbial bacteria, so that a biological film is generated in the inner core, and the microbial bacteria adsorb and degrade pollutants in sewage and metabolize the pollutants in wastewater. The invention has the advantages of realizing high filling density and less clogging in the aspect of sewage treatment, improving the treatment efficiency and increasing the pollutant removal speed.

Description

Membrane biological reduction reactor and process with hydrogen as electron donor

Technical Field

The invention relates to an environment-friendly water treatment device and process, in particular to a membrane biological reduction reactor and process for reducing pollutants in water by using hydrogen as an electron donor to remove the pollutants in the water.

Background

In a typical membrane bioreactor apparatus, the hollow fiber membrane module can increase the effective contact area of the biological membrane with the pollutants in the wastewater to enhance metabolism. After entering the hollow cavity, the gas diffuses and permeates the membrane wall of the hollow fiber membrane and contacts with the biomass outside the membrane, so that oxidized pollutants in the sewage are reduced. When hydrogen is used as the reducing gas, the gas utilization rate is close to 100%, and the residual gas emission is low, so that the operation cost is reduced.

Conventional membrane bioreactor devices generally perform well in laboratory and controlled test environments, but have problems with wastewater treatment. At a given membrane reactor volume and treatment time, a high packing density can increase treatment efficiency, i.e., increase contaminant removal rate. However, high packing density can lead to biofouling, require maintenance (e.g., backwashing, disassembly, cleaning, etc.), and can reduce membrane bioreactor operating efficiency and increase operating costs. Therefore, as high a packing density as possible, with as little fouling as possible and with high nitrogen removal efficiency, are improved goals for the apparatus and system.

Disclosure of Invention

The invention aims to provide a membrane biological reduction reactor taking hydrogen as an electron donor, aiming at the defects in the prior art. The invention comprises a box body 110, an inner core 132, a gas channel and a liquid channel. It is characterized in that the center of the box body 110 is provided with a central core tube 130 provided with a plurality of holes. A core 132 is provided in the case 110. The inner core 132 is a plurality of hollow fibers, and the hollow fibers are fixed between an upper clamping plate 133 and a lower clamping plate 134 in a tubular structure. The upper clamp plate 133 and the lower clamp plate 134 are respectively provided with a sealing ring 142 to be sealed and fixed with the box body 110.

A fiber assembly is provided between the central core tube 130 and the inner wall of the case 100. The upper end cover 144 of the box body 110 is provided with an air inlet 113, the lower end cover 145 of the box body 110 is provided with an air outlet 114, and an air passage is an air passage between the air inlet 113 of the air and the upper end cover 144 as well as the upper clamping plate 133 and is connected with the air outlet 114 through a plurality of hollow fiber inner cores and an air passage between the lower clamping plate 134 and the lower end cover 145. The gas enters from the gas inlet 113, flows through the gas passage between the upper end cover 144 and the upper clamping plate 133, flows through the plurality of hollow fiber pipes, and is discharged from the gas outlet 114 through the gas passage between the lower clamping plate 134 and the lower end cover 145. Inert materials include residual gases, particulate matter in the gases, liquids and solutes diffusing from the outer surface of the hollow fibers into the lumens, dust, microorganisms, and other materials accumulating in the lumens of the hollow fibers. Gas enters the lumens of the hollow fibers 132 from the gas inlet 113 and the majority of the gas diffuses into the hollow fiber walls for biomass growth on the outer surface of the fiber tube walls. The gas may be hydrogen, oxygen or carbon dioxide, depending on the organic matter and its metabolic type.

The outer wall of the box body 110 is provided with a plurality of water outlets 148 at different heights, the inner wall of the box body 110 is provided with a perforated pipe 149, the perforated pipe 149 is connected with the water outlets 148, the water inlet 146 penetrates through the lower end cover 145 to be connected with the central core pipe 130, the liquid channel is that the water inlet 146 of untreated water is connected with the inner core 132 through the water outlet hole on the central core pipe 130 and is connected with the water outlets 148 through a plurality of hollow fibers, fiber components and the perforated pipe 149. Untreated water enters the inner core 132 from the water inlet 146 through the water outlet in the central core tube 130. Flows radially outward, i.e., from the central core tube 130 toward the outer wall of the case 110. Untreated water contacts the outer surfaces of the hollow fibers and forms biomass there. One or more microorganisms contained in the biomass can adsorb and degrade pollutants in the sewage, so that the content of the pollutants in the effluent water is reduced. And exits the outlet 148 through the fiber assembly via the perforated tube 149, thus creating a radial flow of water in a manner that reduces fouling of the biomass in the apparatus. The outer wall or lower end cap 145 of the case 110 is provided with a purge air inlet 115 communicating with the core 132.

One or more water outlet holes are formed in the wall of the central core tube 130.

The hollow fiber has an outer diameter of 250 to 350 μm and an inner diameter of about 120 to 170 μm.

The hollow fibers are made of the following materials: cellulose Triacetate (CTA) or polyethylene terephthalate (PET) or polytrimethylene butylene terephthalate (PTT) or polybutylene terephthalate (PBT) or polyethylene naphthalate (PEN) or polycyclohexylbutylene terephthalate (PCTA) or Polycarbonate (PC), polybutylene naphthalate (PBN) and polylactic acid (PLA).

The polyester can be used for producing hollow fibers of a membrane bioreactor. Many of the advantages of polyester are the ease of processing into fibers and sheets when the fibers are wound and woven into the form of ropes, cloths, and the like. PET and other dihydric alcohols are commonly processed with terephthalic acid polyesters to form ropes.

In addition to production costs, polyesters also have the advantages of high strength, elasticity, abrasion resistance, tensile and compressive resistance. The polyester textile is crease-resistant, mould-resistant, quick-drying and non-deformable during heat treatment for crumpling. The polyester products exhibit excellent resistance to oxidizing agents, detergents and surfactants. UV stabilizers are often required to combat sunlight outdoors or under UV light.

Similar to most thermoplastics, polyesters are recyclable, and virgin polyesters, recycled polyesters, waste polyesters, recycled monomers, and related materials can be recycled. Some polyesters, including PET, are well suited for incineration disposal due to their carbon, oxygen, and hydrogen content alone (i.e., no sulfur, phosphorus, nitrogen, etc.).

The hollow fibers can be bundled into a bundle to form a composite filament, which is then assembled into a module for use in a bioreactor. Hollow fibers of less than 10dtex (Dexitex ═ 1g/10000m) are suitable for making composite filaments, while hollow fibers of more than 100 dtex are often used as monofilaments. The hollow fibers of the intermediate range may then take any of a variety of forms. Both single and composite filaments can be used as the flex fabric and the weft. The hollow fiber is preferably round in shape, and the hollow fiber has a viscosity (T) of 10 to 80cN/tex, preferably 20 to 60 cN/tex.

The fiber assembly is spirally wound in the gaps between the plurality of hollow fibers with the central core tube 130 as an axis.

The fiber component is made of the following materials: cellulose triacetate, polyester, polypropylene, polyethylene, polyurethane, and compounds thereof. The outer diameter of the radial fiber should be 100-500 μm, or 150-450 μm, or 200-400 μm.

The sealing ring 142 is an O-shaped ring or a quadrilateral ring.

The reactors may be operated individually or in parallel or in series.

The membrane bioreactor is provided with a cleaning gas inlet 115 for introducing cleaning gas to the outer wall of the hollow fiber, the cleaning gas inlet being located at the bottom of the tank 110 or above the lower end cap 145. Allowing the scrubbing gas to enter the interior of the cabinet 110 and the outer walls of the hollow fibers. The scrubbing gas can be introduced during normal operation or during backwashing. The washing gas is nitrogen. Flammable or toxic gases are not suitable because the scrubbing needs to be vented to the atmosphere. The scrubbing gas can also be introduced cyclically. Therefore, the membrane bioreactor can also be provided with any number of washing and cleaning agent inlets.

The process of the invention is characterized by comprising the following steps:

A. untreated water enters the inner core 132 from the water inlet 146 through the water outlet hole on the central core tube 130, flows radially outwards to contact with the outer surface of the hollow fiber in a large area, and water treated by the fiber assembly is discharged from the water outlet 148;

B. untreated water enters from the water inlet 146, while gas enters from the gas inlet 113, flows through the plurality of hollow fiber inner core pipelines, is discharged from the gas outlet 114, most of the gas entering the inner cavity of the hollow fiber 132 diffuses into the hollow fiber wall and contacts with the water, so that microbial bacteria on the outer surface of the fiber tube wall grow, and liquid and solute, dust, microorganisms and other substances accumulated in the inner cavity of the hollow fiber are discharged from the gas outlet 114;

C. the inner core 132 forms a biofilm by autotrophic microbial bacteria in the membrane biological reduction reactor, and the oxidized pollutants in the wastewater are metabolized by the microbial bacteria to adsorb and degrade the pollutants in the wastewater.

The pH value in the membrane biological reduction reactor can be preferably maintained at 8-9 so as to ensure that the biomass can grow well. This pH range can be achieved by introducing carbon dioxide into the membrane bioreactor. All membrane bioreactors tested required periodic cleaning to reduce biomass accumulation. The best cleaning effect can be obtained by adopting a scheme of combining backwashing, nitrogen cleaning and intermittent disassembly cleaning.

The circulating water of the membrane biological reduction reactor accounts for 40-50% of the discharged water. And part (such as 40-50%) of sewage is recycled to the radial flow membrane bioreactor, so that the pollutant removal amount can be improved. The main reason is that the treated sewage and the untreated sewage are mixed by circulation, so that the total dissolved oxygen in the sewage is diluted, and the utilization of nitrate as an electron acceptor instead of oxygen by the biomass is promoted.

The membrane biological reduction reactor can improve the speed and the uniformity of sewage flowing through the hollow fibers covered with the biomass, increase the removal of pollutants, reduce biological clogging and improve the periodic cleaning efficiency. The performance test results of various radial flow membrane bioreactors show that the radial flow membrane bioreactor is superior to the traditional membrane bioreactor in other flow forms.

The invention has the advantages that the membrane biological reduction reactor takes hydrogen as an electron donor, realizes high filling density and less clogging in the aspect of sewage treatment, improves the treatment efficiency and increases the pollutant removal speed.

Drawings

FIG. 1 is a schematic cross-sectional structural view of the present invention;

FIG. 2 is a schematic diagram of a test system according to the present invention.

In the figure: 110 outer box body, 113 air inlet, 114 air outlet, 115 cleaning air inlet, 130 central core pipe, 132 inner core, upper clamping plate 133,

lower clamping plate

134, 135 fiber component, 142 sealing ring, 144 upper end cover, 145 lower end cover, 146 water inlet, 148 water outlet and 149 perforated pipe. Reactor 200, automatic feed circulation pump 210, feed reservoir 220, hydrogen delivery system 250, nitrogen delivery system 255, carbon dioxide delivery system 260, sampling port 290, three-way valve 270, nitrogen inlet 256/257.

Detailed Description

Embodiments of the invention are further described below with reference to the accompanying drawings:

referring to fig. 1, a central core tube 130 having a plurality of holes is installed at the center of the box body 110 of the present embodiment, and one or more positions on the wall of the central core tube 130 are provided with water outlet holes. A core 132 is provided in the case 110. The inner core 132 is a plurality of hollow fibers, the hollow fibers are fixed between the upper clamp plate 133 and the lower clamp plate 134 in a tubular structure, and the upper clamp plate 133 and the lower clamp plate 134 are respectively provided with a sealing ring 142 to be sealed and fixed with the box body 110. The sealing ring 142 is an O-shaped or quadrilateral ring. This embodiment is an O-ring seal.

A fiber assembly is provided between the central core tube 130 and the inner wall of the case 100. The fiber assembly is spirally wound in the gaps among the plurality of hollow fibers by taking the central core tube 130 as an axis, and the fiber assembly is a braided fabric formed by the hollow fibers and the radial fibers.

An upper end cover 144 of the box body 110 is provided with an air inlet 113, and a lower end cover 145 of the box body 110 is provided with an air outlet 114. The gas channel is a gas channel between the gas inlet 113 and the upper end cap 144 and the upper clamping plate 133, and is connected with the gas outlet 114 through the gas channel between the lower clamping plate 134 and the lower end cap 145 by a plurality of hollow fiber inner cores. The gas enters from the gas inlet 113, flows through the gas passage between the upper end cover 144 and the upper clamping plate 133, flows through the plurality of hollow fiber pipes, and is discharged from the gas outlet 114 through the gas passage between the lower clamping plate 134 and the lower end cover 145. Inert materials include residual gases, particulate matter in the gases, liquids and solutes diffusing from the outer surface of the hollow fibers into the lumens, dust, microorganisms, and other materials accumulating in the lumens of the hollow fibers. Gas enters the lumens of the hollow fibers 132 from the gas inlet 113 and the majority of the gas diffuses into the hollow fiber walls for biomass growth on the outer surface of the fiber tube walls. The gas may be hydrogen, oxygen or carbon dioxide, depending on the organic matter and its metabolic type.

The outer wall of the box body 110 is provided with a plurality of water outlets 148 at different heights, in this embodiment, four water outlets are provided, which are respectively a water outlet 148, a water outlet 148a, a water outlet 148b, and a water outlet 148 c. Distributed along the length of the outer wall of the housing 110. The inner wall of the box body 110 is provided with a perforated pipe 149, the perforated pipe 149 is connected with the

water outlets

148, 148a, 148b and 148c, and the water inlet 146 is connected with the central core pipe 130 through the lower end cover 145. The inlet 146, which is raw water in the fluid path, is connected to the inner core 132 via the outlet opening in the central core tube 130 and to the

outlets

148, 148a, 148b, 148c via a plurality of hollow fibers, fiber modules and perforated tubes 149. Untreated water enters the core 132 from the water inlet 146 through the water outlet hole of the central core tube 130 and flows radially outward, i.e., from the central core tube 130 toward the outer wall of the tank body 110. Untreated water contacts the outer surfaces of the hollow fibers and forms biomass there. One or more microorganisms contained in the biomass can adsorb and degrade pollutants in the sewage, so that the content of the pollutants in the effluent water is reduced. And exits the outlet 148 or

outlets

148a, 148b, 148c through the fiber assembly via the perforated pipe 149, thus creating a radial flow pattern that reduces fouling of the biomass in the apparatus. The outer wall or lower end cap 145 of the case 110 is provided with a purge air inlet 115 communicating with the core 132.

The membrane biological reduction reactors can be operated independently or in parallel or in series, and the embodiment is operated independently.

The hollow fibers are made of the following materials: cellulose Triacetate (CTA) or polyethylene terephthalate (PET) or polytrimethylene butylene terephthalate (PTT) or polybutylene terephthalate (PBT) or polyethylene naphthalate (PEN) or polycyclohexylbutylene terephthalate (PCTA) or Polycarbonate (PC), polybutylene naphthalate (PBN) and polylactic acid (PLA). The hollow fibers on core 132 of this example were made of melt-spinnable polyester with an outer diameter of 300 μm and an inner diameter of about 150 μm. The fusible polyester is melted, compressed and sprayed out by a spinneret, quenched in water or air flow, expanded by heating for one or more steps, and wound by a winding machine. The hollow fiber is a thin, extremely long, flexible polyester fiber tube, which can be cut at any length. Typically, the outer surfaces of the hollow fibers are exposed to the wastewater and the inner surfaces are in contact with the gas stream. The inner surface forms a hollow structure.

The materials of the fiber component are: cellulose triacetate, polyester, polypropylene, polyethylene, polyurethane, and compounds thereof. The outer diameter of the radial fiber should be 100-500 μm, or 150-450 μm, or 200-400 μm. The fiber assembly of this embodiment is a radial fiber and sandwich material. The radial fibers and the interlayer material are made of cellulose triacetate. The radial fibers were 150 denier polyester with an outer diameter of about 300 μm and an inner diameter of about 150 μm.

The process features of this embodiment include the following steps:

A. untreated water enters the inner core 132 from the water inlet 146 through the water outlet hole on the central core tube 130, flows outwards in the radial direction to be in large-area contact with the outer surface of the hollow fiber, and the water treated by the fiber component is discharged from the

water outlet

148 or 148a, 148b and 148 c;

Testing of membrane bioreduction reactors:

a performance testing system of a membrane biological reduction reactor using hydrogen as an electron donor is shown in figure 2. The system includes the apparatus 200, an automatic feed circulation pump 210, a feed liquid storage tank 220, a hydrogen delivery system 250, a nitrogen delivery system 255, and a carbon dioxide delivery system 260. The sampling port 290 is used for sampling and analyzing. The water to be purified is pumped into a central core tube with holes in the membrane bioreactor 200, flows through the hollow fibers along the radial direction, is collected in the box body and then is discharged from one or more water outlets.

In this system, outlet flow is reversed by two three-way valves 270. In the reverse flow, water flows from the water outlet to the outer wall of the hollow fiber to be cleaned and collected in the central core pipe with the hole, and the backwashing of the hollow fiber is completed. Backwashing is generally carried out 1-6 times per day to reduce the back pressure (pressure drop) in the membrane bioreactor. And (4) reducing the pressure of the membrane bioreactor to a normal value of 1-2 psi through backwashing.

The test system is equipped with a nitrogen delivery system 255 and a plurality (e.g., 2) of

nitrogen gas inlets

256, 257. The nitrogen inlet 256 around the bottom of the membrane bioreactor 200 is used for cleaning the outer surfaces of the tank and the hollow fibers, thereby reducing biomass and reducing pressure drop. Nitrogen inlet 257 is located on the feed line of the perforated core tube of the membrane bioreactor 200 and allows nitrogen to be introduced along the central core tube for further cleaning of the hollow fibers. The gas cleaning is very important for avoiding the biomass overgrowth, and the pressure drop of the membrane bioreactor caused by the overgrowth of the biomass is reduced. The test system is also equipped with a gas isolation outlet valve 295 for introducing nitrogen gas for purging and for removing nitrates formed by reduction of the nitrogen gas. Other inert gases, even air, may be used for gas purging.

The test system is also equipped with a carbon dioxide delivery system 260 and a carbon dioxide inlet. The carbon dioxide may be introduced to adjust (e.g., lower) the pH of the membrane bioreactor 200 or provide a carbon source for the autotrophic microorganisms. For example, as shown in formula 1, nitrate is self-reduced to form hydroxide (OH-). Carbon dioxide reacts with hydroxyl radicals to form bicarbonate. The amount of carbon dioxide introduced is generally related to the amount of nitrate that is reduced and maintains the pH in the membrane bioreactor at 7-8.

2.5H₂+NO₃-→0.5N₂+2H₂O+OH^-(1)。

Claims

1. A membrane biological reduction reactor taking hydrogen as an electron donor comprises a box body (110), an inner core (132), a gas channel and a liquid channel, and is characterized in that a central core pipe (130) provided with a plurality of holes is arranged in the center of the box body (110), the inner core (132) is arranged in the box body (100), the inner core (132) is a plurality of hollow fibers, the hollow fibers are tubular structures and are fixed between an upper clamping plate (133) and a lower clamping plate (134), sealing rings (142) are respectively arranged on the upper clamping plate (133) and the lower clamping plate (134) and are fixed with the box body (110) in a sealing way, a fiber assembly is arranged between the central core pipe (130) and the inner wall of the box body (100), an air inlet (113) is arranged on an upper end cover (144) of the box body (110), an air outlet (114) is arranged on a lower end cover (145) of the box body (110), the gas channel is an air channel between the air inlet (113, the water inlet (146) of untreated water is connected with the inner core (132) through a plurality of hollow fiber inner cores and an air channel between the lower clamping plate (134) and the lower end cover (145) and is connected with the air outlet (114), a plurality of water outlets (148) are arranged on the outer wall of the box body (110) at different heights, a porous pipe (149) is arranged on the inner wall of the box body (110), the porous pipe (149) is connected with the water outlets (148), the water inlet (146) penetrates through the lower end cover (145) and is connected with the central core pipe (130), the liquid channel is that the water inlet (146) of untreated water is connected with the inner core (132) through a water outlet on the central core pipe (130), the water inlet is connected with the water outlets (148) through a plurality of hollow fibers, fiber components and the porous pipe (149), and a cleaning air inlet (115.

2. The membrane biological reduction reactor using hydrogen as an electron donor according to claim 1, wherein the wall of the central core tube (130) is provided with a plurality of water outlet holes.

3. The membrane bioreduction reactor with hydrogen as an electron donor according to claim 1 wherein the hollow fibers have an outer diameter of 250 to 350 μm and an inner diameter of about 120 to 170 μm.

4. The membrane bioreduction reactor with hydrogen as electron donor according to claim 1, characterized in that the hollow fibers are made of: cellulose triacetate or polyethylene terephthalate or polytrimethylene terephthalate or polybutylene terephthalate or polyethylene naphthalate or polycyclohexylbutylene terephthalate or polycarbonate or polybutylene naphthalate or polylactic acid.

5. The membrane bioreduction reactor with hydrogen as an electron donor according to claim 1, wherein the fiber assembly is a braided fabric of hollow fibers and radial fibers, and the fiber assembly is spirally wound in the gaps among the hollow fibers with a central core tube (130) as an axis.

6. The membrane bioreduction reactor with hydrogen as electron donor according to claim 1, characterized in that the material of the fiber assembly is: cellulose triacetate, polyester, polypropylene, polyethylene, polyurethane, and compounds thereof. The outer diameter of the radial fiber should be 100-500 μm, or 150-450 μm, or 200-400 μm.

7. The membrane bioreduction reactor with hydrogen as an electron donor according to claim 1 and wherein the sealing rings are O-rings or quadrilateral rings (142).

8. The membrane bioreduction reactor with hydrogen as electron donor according to claim 1 characterised in that the membrane bioreduction reactors can be used individually or in parallel or in series.

9. A process for using the membrane bioreduction reactor of claim 1 with hydrogen as an electron donor comprising the steps of:

A. untreated water enters the inner core (132) from the water inlet (146) through the water outlet hole on the central core pipe (130), flows outwards along the radial direction to be in large-area contact with the outer surface of the hollow fiber, and the water treated by the fiber component is discharged from the water outlet (148);

B. untreated water enters from the water inlet (146), meanwhile, gas enters from the gas inlet (113), flows through the hollow fiber inner core pipelines, is discharged from the gas outlet (114), most of the gas entering the inner cavity of the hollow fiber (132) diffuses into the wall of the hollow fiber and contacts with the water, so that microbial bacteria on the outer surface of the wall of the fiber pipe grow, and liquid entering the inner core, solute, dust, microorganisms and other substances accumulated in the inner cavity of the hollow fiber are discharged from the gas outlet (114);

C. autotrophic microorganism bacteria are arranged in the membrane biological reduction reactor, a biological membrane is formed on the inner core (132), and the microorganism bacteria adsorb and degrade pollutants in the sewage and metabolize oxidized pollutants in the wastewater.