Apparatus and method for supporting phototrophic biofilms

Abstract

This specification describes a module for supplying light to phototrophic organisms in water. Optionally, the module also has a gas transfer membrane. In some examples, the module supports a phototrophic organism film. In some examples, the module is inserted into a tank, which can be a treatment tank of a wastewater treatment system having suspended biomass. This specification also describes a composite wastewater treatment system comprising phototrophic organisms and non-phototrophic organisms.

Description

[0001] Cross-references to related applications This application claims the benefit and priority of U.S. Provisional Application No. 63 / 562,799, filed March 8, 2024, which is incorporated by introduction. Technical Field

[0002] This specification relates to wastewater treatment, phototrophic biofilm reactors, and methods for growing phototrophic organisms. Background Technology

[0003] paper Novel waveguide reactor design for enhancing algal biofilm growth SN Genin et al., Algal Research 12 (2015) 529-538, describe an algal membrane photobioreactor with a luminescent waveguide capable of distributing a bright light source over a large surface area. The waveguide is placed in water within a parallel-plate airlift reactor. Carbon dioxide bubbles and nutrient culture medium are added to the water. Algal biofilms are cultured on the waveguide. Summary of the Invention

[0004] This specification describes a module for supplying light to phototrophic organisms in water. In some instances, the module supports a phototrophic biofilm. In some instances, the module is inserted into a tank, which may be a treatment tank in a wastewater treatment system.

[0005] The module has multiple light-emitting filaments extending from at least one manifold. In some instances, one or more light-emitting filaments are combined with one or more hollow fiber gas transport membranes to form light-emitting cords, and the multiple light-emitting cords extend from the manifold. A light source is connected to the manifold. Optionally, a gas source may also be connected to the manifold. In some instances, the module has a second manifold and the light-emitting filaments extend between the two manifolds. Optionally, a light source may be connected to each manifold. Optionally, a gas source may be connected to one manifold and gas may be discharged from the other manifold.

[0006] Modules can be made by encapsulating multiple luminescent filaments, multiple luminescent cords, and / or multiple gas-transmitting fibers or cords. The encapsulated filaments, fibers, or cords are attached to a manifold housing to form a manifold. Outside of the manifold, the filaments, fibers, or cords are typically independent of each other. Multiple modules can be attached to a common frame to form a box. Different types of filaments, fibers, or cords can be mixed within a module, between different modules within a box, or between different boxes located in the same tank or the same wastewater treatment system.

[0007] In wastewater treatment systems, treatment units for the growth of phototrophic organisms are integrated with activated sludge systems or systems having one or more treatment units with non-phototrophic organisms. Non-phototrophic organisms may include heterotrophic denitrifying bacteria. In some instances, the treatment units for the growth of phototrophic organisms are provided by one or more modules or boxes submerged in a tank and connected to a light delivery system. Optionally, one or more modules or boxes may be connected to a gas delivery system. Optionally, the modules or boxes connected to the light delivery system may also be wholly, partially, or entirely connected to the gas delivery system. In some instances, the system includes a separate diffuser for introducing carbon dioxide into the treatment tank. In some instances, the system includes a gravity selector.

[0008] The wastewater treatment method includes the steps of growing phototrophic organisms and growing non-phototrophic organisms. Phototrophic organisms convert carbon dioxide into organic molecules. Non-phototrophic organisms may include heterotrophic denitrifying bacteria. Non-phototrophic organisms may consume some of the phototrophic organisms. In some instances, the method includes supplying water to a tank and supplying light, and optionally gas, to filaments or cords of a module or box. In some instances, the biofilm of the phototrophic organisms is cultured on the filaments or cords. Excess biofilm can be removed, for example, by introducing flushing bubbles into the tank. Optionally, phototrophic particles derived from detached biofilm can be retained by a solid-liquid separation system that optionally includes a gravity selector.

[0009] Another method of wastewater treatment involves supplying water into a tank and supplying light and, optionally, gas into the water in the tank to enable the growth of phototrophic organisms. Phototrophic particles derived from the phototrophic organisms are retained by a solid-liquid separation system that optionally includes a gravity selector. Attached Figure Description

[0010] Figure 1 An example of a light-diffusing cord is shown.

[0011] Figure 2 This is a schematic diagram of a machine used to manufacture ropes and threads.

[0012] Figures 3 to 5 This is a schematic diagram of the steps in a method for manufacturing a module comprising multiple ropes.

[0013] Figure 6 This is a schematic diagram of a module that includes multiple ropes.

[0014] Figure 7 It includes Figure 6 A schematic diagram of the reactor module.

[0015] Figure 8 It includes Figure 6 A schematic diagram of an activated sludge plant with modular components.

[0016] Figure 9This is a schematic diagram of an activated sludge plant, including a gravity selector. Detailed Implementation

[0017] Figure 1 A cord 10 is shown. The cord comprises one or more luminescent filaments. In some instances, the luminescent filaments are side-emitting fiber optic cables, alternatively referred to as side-emitting fiber, side-emitting cable, or other similar names. Side-emitting fiber optic cables are typically transparent and emit the color of light input to them. Side-emitting fiber optic cables are readily available as monofilaments with a diameter of 0.5-12 mm, or more typically 1-12 mm. Diameters in the 1-3 mm range are preferred due to their flexibility and high surface area-to-volume ratio. Side-emitting fiber optic cables can also be available as multi-strand cables with a set of twisted filaments within a transparent sheath. Each filament has a diameter in the range of 0.5 to 1.0 mm and is flexible enough to wrap around other filaments. In applications as described herein, the monofilament or set of filaments is optionally removed from the multi-strand cable sheath or obtained from a supplier and then incorporated into the multi-strand cable sheath. Smaller diameter luminescent filaments are already commercially available and can be produced using current production methods, or may be available in the future.

[0018] The cord 10 may include two or more of the following: a) a core 12, b) one or more warp filaments 14, and c) one or more winding filaments 16. Figure 1 In this example, all three elements are present, although the core 12 is not visible behind the warp filament 14. The core 12 can be, for example, a monofilament or yarn, such as a twisted or braided yarn. The warp filament 14 typically extends parallel to the core 12 but is not mechanically entangled with it. The winding filament 16 spirally wraps around the warp filament 14 and / or the core 12. Some or all of the filaments in the core 12, warp filament 14, or winding filament 16 can be air-transmitting filaments. Some or all of the filaments in the core 12, warp filament 14, or winding filament 16 can be luminescent filaments.

[0019] exist Figure 1In this example, core 12 comprises one or more luminescent filaments. Core 12 may have a diameter of 0.5 to 6 mm, optionally ranging from 0.5 mm to 2.0 mm. Warp filament 14 is a gas transport membrane. For example, warp filament 14 may be melt-spun hollow fibers with an outer diameter of 100 micrometers or less. In some examples, the hollow fiber gas transport membrane has dense walls (i.e., non-porous) and is made of, for example, polymethylpentene (poly(4-methylpentene-1) or PMP). In other examples, the hollow fiber gas transport membrane may be semi-porous (i.e., having pores smaller than about 40 angstroms that do not allow large amounts of water to enter) or hydrophobic and porous. Wound filament 16 may be a multifilament yarn or a monofilament. Multifilament yarn may comprise twisted or otherwise combined filaments or filaments simply gathered together in bundles or tufts. Wound filament 16 may be wound around core 12 in a clockwise or counterclockwise spiral. In the example shown, the rope 10 has multifilament bundles of wound wires 16 in each direction.

[0020] exist Figure 1 In one example, the warp filaments 14 cover some surface areas of the light-emitting core 12. However, light is scattered outward through the gaps between the individual warp filaments 14 and may also pass through the warp filaments 14 themselves. The biofilm of the phototrophic organism grows on the cord 10, for example, in the gaps between the warp filaments 14 and the core 12, in the gaps between different warp filaments 14, and to some extent on the outer side of the warp filaments 14. Optionally, it can provide a higher density of light than the light-emitting core 12. Figure 1 The diagram shows fewer warp filaments 14, thus exposing more surface area of ​​the light-emitting core 12.

[0021] In another instance, luminescent monofilaments or multiple luminescent filaments twisted, wound, or woven together are used individually, without being incorporated into rope 10. The biofilm of the phototrophic organism grows on the exposed surface of the luminescent monofilaments or filaments.

[0022] In another example, multiple luminescent filaments are twisted or woven together to form a core 12, or arranged along the core 12 as warp threads 14 or winding threads 16. Optionally, one or more non-luminescent winding threads 16 may be added to prevent the underlying filaments from separating from each other.

[0023] In another example, the core 12 is provided by a hollow fiber gas transport membrane. The gas transport membrane can have a diameter ranging from 0.5 to 2 mm. The gas transport membrane can be made of silicone (e.g., PDMS) or thermoplastic. One or more light-emitting filaments are provided as warp filaments 14 or winding filaments 16. If the light-emitting filaments are provided as warp filaments 14, one or more winding filaments 16 can be added to prevent the light-emitting filaments from separating from the core 12.

[0024] In another example, a hollow fiber monofilament gas transport membrane or an assembly comprising one or more gas transport membranes (such as rope 10) is separate from a luminescent monofilament or an assembly comprising one or more luminescent membranes (such as rope 10) but used in the same reactor.

[0025] In another example, the cord 10 has one or more luminescent filaments as a core 12, a hollow fiber gas-transmitting membrane as a warp filament 14, and additional luminescent filaments in one or more winding filaments 16. In yet another example, the cord 10 has one or more luminescent filaments in a core 12, a hollow fiber gas-transmitting membrane as a warp filament 14, and one or more multifilament bundles or yarn winding filaments 16 that do not include either gas-transmitting or luminescent filaments. The winding filaments 16 may be made of a transparent or semi-transparent polymer (such as polyester). Optionally, in any of the examples described in this paragraph, the core 12 may have luminescent monofilaments of 0.5 to 2.5 mm or multiple luminescent filaments twisted, wound, or braided together.

[0026] Other examples may be used, including structures with one or more luminescent filaments, one or more gas transport membranes, or both. Typically, these structures, including the examples described above, have an outer diameter of 0.5 to 6 mm or 0.5 to 5 mm. The outer diameter of the structure (e.g., cord 10) can be measured as the smallest aperture through which cord 10 will pass. Anomalies, defects, or non-repeating protrusions are ignored in these measurements.

[0027] The luminescent filament can be made of, for example, poly(methyl methacrylate) (PMMA). IUPAC stands for poly(methyl 2-methylpropionate). PMMA is an amorphous glassy material, sometimes called acrylic or plexiglass. PMMA transmits light in the wavelength range of approximately 300-2,800 nm. PMMA also scatters a portion of the transmitted light from the sides of the filament. PMMA-side-emitting optical fiber filaments are commercially available from multiple sources and are used, for example, in architectural lighting. The light scattered from the sides of the PMMA filament can be increased by various methods, such as scraping or sanding the surface of the filament or stretching the filament. The inventors also believe that the scattered light can be increased by bending the PMMA filament, as occurs, for example, when one PMMA filament is wound around another filament.

[0028] Figure 2A machine 20 for manufacturing the rope 10 is shown. Machine 20 is built on a frame 22 that supports and aligns various components. A core 12 and one or more warp yarns 14 are supplied from a yarn rack 24 to machine 20. The yarn rack 24 has a fixed bobbin holder, guides, and tensioning devices, as seen in other textile equipment. The warp yarns 14 pass through a distributor 28. The distributor 28 may have a central opening and one or more eyelets surrounding the central opening. The core 12 and warp yarns 14 are unwound from bobbins on the yarn rack 24, positioned at the top of the distributor 28 by guide rollers, and supplied vertically downward through the distributor 28. A take-up and winding machine (not shown) pulls the rope 10 downward, through machine 20, and onto bobbins. In other examples, a core 12 is present but no warp yarns 14 are present. In other examples, warp yarns 14 are present but no core 12 are present.

[0029] Optionally, one or more spindles 30 or other yarn winding devices are located below the distributor 28. Each spindle 30 is loaded with yarn, and as the yarn passes through the spindle 30, the spindle winds the yarn around one or more warp threads 14 or cores 12. As the core 12 moves downward, each wound yarn forms a helical wound yarn 16. The machine 20 may also have an alignment guide (not shown) to keep the core 12 aligned with the central axis of the spindle 30 and to reduce vibration of the core 12.

[0030] An example of a suitable spindle 30 is the Oerlikon Textile Temco™ spindle model MSE150. Each spindle 30 has a motor and a hollow core, and holds the bobbin of the wound yarn 16. The spindle 30 is positioned such that its central axis coincides with the core 12. Figure 2 In machine 20, there are two spindles 30, one rotating clockwise and the other counterclockwise. The spindles 30 can rotate at adjustable speeds up to 25,000 rpm to provide controllable pitch. Alternatively, a rotating yarn carrier can be used instead of the spindles 30. In the rotating yarn carrier, bobbins are mounted on wheels that rotate around the core 12 in one direction without contacting it. Each bobbin is preferably equipped with tension control.

[0031] Multiple cords 10 (or other filaments or fibers, or combinations thereof) (e.g., 100 or more) can typically be manufactured into modules in a manner consistent with the manufacture of submerged hollow fiber membrane filter modules. At least one end of each cord 10 is encapsulated in a block of encapsulating material (such as a thermoplastic or thermosetting resin), which is then sealed to a disc (i.e., a manifold housing) to form a manifold. The ends of any gas transport membranes and / or luminescent filaments open into the interior of the manifold, for example, by cutting them after encapsulation. The other end of the cord 10 can be encapsulated in another manifold, wherein the ends of the gas transport membranes and luminescent filaments are open or closed, closed individually, or looped back and encapsulated in the first manifold.

[0032] An optional port in the manifold allows gas to be supplied to the interior of the gas transfer membrane 14. Gas can be supplied to the gas transfer membrane 14 either as a dead end or by venting through a second manifold.

[0033] Light is supplied to the luminescent filament from a light source located within a manifold or, for example, connected to the manifold via one or more fiber optic cables. Optionally, the light source may also be configured to connect to a second manifold, such that the luminescent filament receives light from both ends. The light source may include lamps, such as LEDs. Alternatively or additionally, the light source may include a solar collector. The lamp may be selected to produce light at wavelengths suitable for the growth of selected phototrophs. Optionally, sunlight may be filtered to produce light at wavelengths suitable for the growth of selected phototrophs. Light may be supplied continuously or at a cycle, for example, 12 hours per day, to simulate the daily solar cycle.

[0034] As an example, cord 10 (or other filaments or fibers, or combinations thereof) can be assembled into modules or boxes according to the ZeeWeed 500™ immersion membrane filtration unit sold by Veolia. Sheets of cord 10 are prepared, wherein the cords 10 are spaced substantially evenly within the sheet. Multiple sheets are stacked on top of each other to form a bundle with adjacent sheets spaced apart from each other. The bundle is potted. After the potting material has cured, it is cut to expose the open ends of the cord 10 and sealed to a manifold disc. Several such modules can be attached to a common frame, their ports connected together via manifolds to form a box. Various useful techniques that can be used or adapted for manufacturing modules are described in U.S. Patents 7,169,295, 7,300,571, 7,303,676, U.S. Publication 2003 / 01737006 A1, and International Publication No. WO 02 / 094421, all of which are incorporated herein by reference. Alternatively, other known techniques for manufacturing hollow fiber membrane modules can be used.

[0035] Reference Figure 3 Multiple cords 10 (or other filaments or fibers, or combinations thereof) or wavy cords 10 are laid on a flat jig or drum to provide a set of generally parallel segments of cords 10 within a sheet 38. The segments of cord 10 can be kept evenly spaced from each other within the sheet 38, for example, by braiding filaments 40 or hot-melt adhesive strips 42. When using segments of cord 10, the ends of cord 10 can be sealed, for example, by melting them along a sealing line 44 with an iron or hot-cutting blade. Multiple sheets 38 can be stacked on top of each other, preferably with the ends of adjacent sheets 38 separated by spacers. The ends of this set of sheets 38 are placed in a potting mold 46 and filled with potting resin 48 flowing by gravity or centrifugal force. The potting resin 48 can be, for example, a polyurethane resin, formulated to penetrate into and seal around the various filaments of cord 10.

[0036] Reference Figure 4 After the potting resin 48 has cured, the sheet 38 is removed from the potting mold 46. To expose any open ends of the gas transport membrane and the light-emitting filament, the potting resin 48 is cut along the cut line 50. The other end of the sheet 38 can be potted in the same manner. Optionally, one or two blocks of potting resin 48 can be cut to expose any open ends of the gas transport membrane and the light-emitting filament.

[0037] Reference Figure 5 The manifold 60 is formed by sealing a block of potting resin 48 onto a manifold tray 52. ​​The manifold tray 52 may be made of molded plastic. Optionally, the manifold tray 52 has an outlet 54 that allows gas to enter and exit the manifold 60. Optionally, the manifold tray 52 has an optical cable 55, such as an optical fiber cable, for introducing or expelling light into or out of the manifold 60. The distal end of the optical manifold 55 may be connected to a light source or another manifold 60.

[0038] The block of potting resin 48 can be held in the manifold 52 by an adhesive or by a gasket 56 between the periphery of the potting resin 48 and the manifold 52. Optionally, a second potting material 58 can be poured onto the potting resin 48. The second potting material can further seal the cord 10 or the potting resin 48 to the manifold 52, or can cushion the cord 10 where it exits the manifold 60. A similar manifold 60 can be fabricated at the other end of this set of sheets 38. In other instances, the block of potting resin 48 is cured directly (rather than in a separate mold) in the manifold 52 according to methods known in the art of manufacturing hollow fiber membrane modules.

[0039] Reference Figure 6 Module 66 has two manifolds 60, with ropes 10 extending between them. The manifolds 60 are preferably vertically aligned and held apart by a frame 62. The length of the rope 10 between the opposite faces of the manifolds 60 may be slightly greater than the distance between the opposite faces of the manifolds 60. In this case, the rope 10 has a certain slack and can swing. The ropes 10 are preferably not connected to each other between the manifolds 60. Although one rope 10 may come into contact with another when it swings, the movement of the rope 10 is generally independent of the other ropes 10. Multiple modules 60 can be secured in a common frame 62. The frame 62 also secures the aerator 68 near the bottom of the module 66.

[0040] When used for wastewater treatment, rope 10 (or other filaments or fibers, or in combination with other filaments or fibers) is immersed in the treatment tank of a bioreactor. A gas (e.g., air, carbon dioxide, hydrogen, or another gas) is supplied through the inner lumen of any gas transport membrane. Light is provided through any luminescent filament. A biofilm may form on the outer surface of rope 10 or other filaments or fibers. Alternatively or additionally, rope 10 or other filaments or fibers may supply light and / or gas for use by suspended organisms or organisms in a biofilm of other ropes 10, filaments, or fibers.

[0041] The modules of rope 10 can be deployed in a bioreactor by immersing them in the treatment tank of a wastewater treatment system. A box frame can be used to facilitate the deployment of multiple modules, with the rope 10 vertically oriented into an open tank. Gas injection at a low rate can be provided to renew the liquid around the rope 10 by generating bubbles below or near the bottom of the module. Gas injection at a higher rate can be used to help control biofilm thickness through the direct action of bubbles, bubble wakes, or bubble pressure on the biofilm, or by causing the rope 10, loosely installed between manifolds, to oscillate in the water to create turbulence or contact between the ropes 10. Optionally, gas discharged from any gas transfer membrane can be recycled for gas injection or blended with process gas.

[0042] Reference Figure 7 Module 66 is submerged in tank 70. Tank 70 is filled with water to be treated from inlet 72. The treated water is removed through outlet 74. Optionally, water can be recirculated from outlet 74 to inlet 72 to allow water to flow through module 66, mixing tank 70, or to maintain the desired conditions in tank 70. Optionally, outlet 74 can be directly or indirectly connected to a solid-liquid separation device, and some solid-rich portion of the effluent from outlet 74 can be directly or indirectly recirculated to inlet 72. Tank 70 can be part of a series of tanks in a wastewater treatment plant.

[0043] Carbon dioxide, hydrogen, air rich in carbon dioxide and / or hydrogen, or other gases may optionally be blown into or drawn from module 66 by a first gas blower 76. In the illustrated example, gas is blown into a first manifold 60, travels through rope 10, and exits from a second manifold 60. Optionally, the exited gas is recirculated back to the first manifold by a second gas blower 80.

[0044] Wastewater treatment plants tend to discharge gaseous carbon dioxide present in the incoming wastewater or produced by the metabolism of microorganisms that metabolize organic carbon (BOD) in the water. The partial pressure of carbon dioxide in water can be higher than its partial pressure in air. The flow rate of gas through a dense-walled membrane is proportional to the gas's permeability coefficient in the membrane material and the transmembrane partial pressure difference. Therefore, to transfer carbon dioxide into water through a gas transfer membrane, it may be necessary to use a carbon dioxide-rich gas or increase the absolute pressure of the gas within the membrane's cavity. Gas recirculation via a second gas blower 80 allows the pressure in the recirculation loop to be greater than atmospheric pressure.

[0045] In most dense-walled membranes, the permeability of carbon dioxide is 3 to 5 times that of oxygen. By controlling the concentration of the inflow gas, the cavity pressure, the recirculation rate, and the partial pressure in the water, carbon dioxide and oxygen can be transported through the gas transport membrane at various absolute or relative rates. These absolute and / or relative rates, optionally combined with other factors such as pH, nutrient supply, mechanical stress (e.g., by flushing bubbles) or biological stress (e.g., by periodic changes in gas or nutrient supply), can be used to preferentially cultivate desired types of phototrophic organisms.

[0046] Optionally, such as at night or when light is not supplied to phototrophs, a gas transport membrane can be used to extract and collect carbon dioxide from the water. The collected gas can be stored and reused as a carbon dioxide-rich gas supply when light is supplied to the phototrophs.

[0047] A throttle valve 78 can be used to discharge exhaust gas from the recirculation loop, allowing fresh gas to be added via the first gas blower 76. Alternatively or additionally, an aeration valve 79 can be used to supply gas continuously or intermittently to an aerator 68 below module 66. Bubbles from aerator 68 can be used in mixing tank 70 or to control the thickness of the biofilm on cord 10. Optionally, aerator 68 may include a supply pipe 82 and a transducer 84. Transducer 84 collects the gas ejected from the supply pipe in a bag below housing 86. A large number of bubbles are released periodically. The flow rate of bubbles from aerator 68 can be controlled to prevent excessive biofilm growth on cord 10. Optionally, a light sensor near cord 10 can be used to measure light diffusion resistance, which can be used as an indicator of whether the biofilm thickness is within the desired range.

[0048] Light is supplied from light source 57 to any emitting filament in module 66. Light source 57 is connected to manifold 60 via optical cable 55. Light emitted in manifold 60 enters the end of any emitting filament. Alternatively, as Figure 8 As shown, light can be provided by a lamp (such as an LED) in the manifold 60 of the module. Light enters the water and / or the attached biofilm from the side of the luminescent filament.

[0049] Light can be provided by artificial light sources, collected sunlight, or both. Light can be provided during daylight hours, during artificially extended daylight hours, or continuously. The intensity and duration of light can be controlled, optionally in combination with the supply of gases and / or one or more nutrients, to provide a selected rate of carbon dioxide assimilation in the phototrophic biofilm. The desired rate of carbon dioxide assimilation may be related to, for example, the supply of organic carbon to other organisms in the wastewater system as a whole, such as heterotrophic denitrifying bacteria, via phototrophic materials.

[0050] In some instances, module 66 has a cord 10 comprising both light-emitting filaments and gas-transporting filaments. In some instances, module 66 has light-emitting filaments separate from the gas-transporting membrane, said light-emitting filaments being either monofilaments or within the cord. The gas-transporting membrane may be a hollow fiber membrane monofilament or within the cord. In some instances, the gas-transporting membrane may be located in a separate sheet from the light-emitting filaments. In other instances, the gas-transporting membrane and the light-emitting filaments alternate within each sheet.

[0051] In other instances, one module 66 has a gas transport membrane but no light-emitting filaments, and another module 66 in the same box has light-emitting filaments but no gas transport membrane. In other instances, one box in a wastewater treatment system has a gas transport membrane but no light-emitting filaments, and another box in the wastewater treatment system has light-emitting filaments but no gas transport membrane.

[0052] As noted above, conventional wastewater treatment plants tend to produce excess carbon dioxide, which escapes as exhaust gas from the surface of the treatment tanks into the atmosphere. Cultivating phototrophic organisms in the wastewater treatment system allows some of the excess carbon dioxide to be converted into organic carbon, which reduces greenhouse gas emissions from the wastewater treatment plant. Organic carbon is embedded in the phototrophic organisms and is released when excess biofilm is removed from module 66. This excess phototrophic material can be removed from the system, for example, through solid-liquid separation of the effluent. The carbon in the removed biomass can be, for example, sequestered (e.g., by pyrolysis, hydrothermal carbonization, hydrothermal gasification, drying, or application to soil) and / or converted into methane and carbon dioxide by an anaerobic digester. Many phototrophic organisms also incorporate soluble nitrogen and phosphorus into organic molecules, and the removal of excess phototrophic material helps to directly reduce nitrogen and phosphorus concentrations in the wastewater treatment plant effluent. Alternatively, some excess phototrophic material can be retained in the wastewater treatment system as a carbon source for other microorganisms. Since removing nitrogen to low levels typically requires the addition of organic carbon to wastewater treatment plants, providing organic carbon via photobiomass can reduce or eliminate the need for supplemental carbon sources. Optionally, carbon dioxide can be added via module 66 or via a separate carbon dioxide injector to increase the generation of organic carbon in the form of photobiomass for use by heterotrophic denitrifying bacteria in the wastewater system, sequester carbon dioxide, produce biomass for conversion into methane or fertilizer, or enhance the ability of photobiomasses to remove nitrogen and phosphorus directly from wastewater.

[0053] like Figure 7 As shown, module 66 occupies approximately one-third to one-half of the volume of tank 70. However, module 66 may occupy more or less of the volume of tank 77 or the total volume of tanks in the wastewater treatment system, for example, 5-95%.

[0054] Reference Figure 8Module 66 has luminescent filaments, optionally as monofilaments or in ropes, and optionally has a gas transport membrane, optionally in a rope with luminescent filaments or in a separate rope or monofilament. Multiple modules 66 are attached to a common frame to form a box 80. One or more boxes 80 are inserted into one or more tanks of an activated sludge plant 82. The sludge plant includes an aerobic tank 88 and a secondary separation unit 90. The secondary separation unit may be, for example, a clarifier or a membrane filtration module as shown in the example. Optionally, the activated sludge plant 82 may include additional tanks, such as an anaerobic tank 84 and / or an anoxic tank 86. Other types and arrangements of tanks may also be used. Multiple tanks may be replaced by partitions within the tanks. In the example shown, the box 80 is placed in the aerobic tank 88. In other examples, the box 80 may be placed in different tanks. The box 80 provides enhanced carbon capture and redirection for the activated sludge plant 82. The box 80 may include an aerator to flush excess biofilm from the module 66. Optionally, the aerator is a pulse aerator, such as the LEAP™ aerator available from Veolia Water Treatment Solutions.

[0055] Secondary separation units (e.g., clarifiers, membrane filters, dissolved air flotation units, etc.) produce effluent and activated sludge. A portion of the activated sludge is returned (returned activated sludge, RAS) to the main treatment tank. Another portion of the activated sludge is waste (waste activated sludge, WAS). WAS may optionally be sent to the anaerobic digester after mixing with and / or thickening the primary sludge. Optionally, the liquid portion of the concentrated filtrate and / or anaerobic digester sludge (e.g., dewatered centrifuge liquor) may also be returned to the main treatment tank. Some organic carbon in the phototrophic material can be converted to methane in the anaerobic digester for reuse as fuel. Some organic carbon in the phototrophic material can be converted to carbon dioxide in the anaerobic digester, and optionally, after purifying the anaerobic digester gases, some or all of the carbon dioxide produced in the anaerobic digester (from the digestion of phototrophic material or other solids) can be used to grow more phototrophic material. Some organic carbon in photonutrients can be found in anaerobic digester sludge (or sludge that has not undergone anaerobic digestion), which can be dried or pyrolyzed for long-term disposal or sequestration, and / or applied to land as a soil conditioner or to sequester carbon in the soil.

[0056] Figure 9Another activated sludge plant 82 is shown. In this example, a portion of activated sludge 96 (indicated as spent activated sludge 94) is fed to a gravity selector 92. The gravity selector 92 can be, for example, a hydrocyclone. The gravity selector 92 removes the dense portion 98 of solids from the spent activated sludge 94 and returns this dense portion 98 to the main treatment line of the activated sludge plant 82, for example, to the anaerobic tank 84. The dense portion 98 may include phototrophic particles, which are solid aggregates comprising phototrophic organisms, including phototrophic organisms previously detached from the biofilm on the photoluminescent filaments. The phototrophic organisms in the phototrophic particles may be dormant, but retain a carbon source in the activated sludge plant 82, which can be used by other organisms such as heterotrophic denitrifying bacteria.

[0057] A portion of the waste sludge bypassing gravity selector 92 and the liquid effluent from gravity selector 92 can be further treated, for example, by concentration and dewatering, hydrolysis, anaerobic digestion and / or pyrolysis, hydrothermal carbonization, hydrothermal gasification, or drying. The organic carbon in the waste sludge is thus converted into methane and / or stored in solid form for sequestration and / or reuse, for example, as a soil conditioner.

[0058] although Figure 8 and Figure 9 Module 66 is shown for use in conjunction with a wastewater treatment system, but phototrophic organisms can alternatively be grown in other forms of suspended growth or biofilm reactors. Suspended growth bioreactors include, for example, photobioreactors (e.g., those with phototrophic organisms grown in transparent bags or tubes) and raceway tanks. Biofilm reactors include, for example, reactors with rotating wheels and belts. While these types of reactors can be used, Module 66 is preferred because it is consistent with the form of tanks commonly used in wastewater treatment plants and is efficient in terms of material usage. However, many of the systems and methods described herein (e.g., converting excess or added carbon dioxide into organic carbon for use by heterotrophic denitrifying bacteria) can also be applied in conjunction with other methods of growing phototrophic organisms.

[0059] In some instances, the shedding of phototrophic biofilms allows for the transfer of the biofilm to the host liquid within the wastewater treatment plant. This enables the synergistic use of organic carbon stored in the phototrophic biofilm (e.g., purple bacteria) to further remove nitrates (from 10-15 mg N / L to <3-7 mg N / L, preferably but not limited to <25 mg N / L to <10-15 mg N / L) by heterotrophic denitrifying bacteria contained in the host liquid. Synergistic use may also be achieved through dissolved oxygen produced by the phototrophic biofilm (e.g., cyanobacteria) to supply oxygen for enhancing autotrophic nitrification by nitrifying bacteria contained in the host liquid (from 5 mg N / L to <1 mg N / L, preferably but not limited to <100 mg N / L to <5 mg N / L), or to increase the dissolved oxygen concentration in the host liquid of the bioreactor. In some instances, the dissolved oxygen (DO) concentration can be increased from 0 to 9 mg O2 / L or until saturation, preferably completely replacing or partially or completely offsetting the oxygen supply from a fine bubble diffusion system typically located at the bottom of the aeration tank. In some instances, 0 to 0.5 mg O2 / L can be provided by a conventional fine bubble diffuser, and 0.5 to 9 mg O2 / L, preferably 0.5 to 4 mg O2 / L, can be provided by a photobiofilm.

[0060] The solids residence time (SRT) of phototrophs in a bioreactor can be increased by allowing the formation and enhancement of phototrophic particles in the host liquid mixture, wherein the phototrophs are initially contained in photobiofilm detachments colonized in the host liquid. The mixture may contain a combination of phototrophic flocs (particle size 10 to 200 micrometers) and phototrophic particles (particle size 200 to 1000 micrometers). The SRT of the phototrophic floc-phototrophic particle combination can be increased by 2 to 10 times, resulting in an SRT of 1 to 100 days.

[0061] The volatile solids (VS) content of the spent activated sludge sent to the sludge treatment line can increase from 50-75% to 76-90%, leading to further carbon capture and biogas production, for example, from 0.8-0.9 Nm³. 3 Biogas removal per kg VS increased to 0.91 to 1.5 Nm³. 3 Biogas / kg VS removal.

[0062] In some instances, there is a synergistic use and assimilation of CO2 produced by host liquid microorganisms such as heterotrophs by a photobiofilm grown on module 66 or another biofilm device.

[0063] In some instances, there is synergistic use of CO2 (20 to 30% v / v) produced by anaerobic digestion, which can be purified (e.g., removing condensate and / or >90% v / v CO2 content) and fed into the gas transport membrane of module 66. The carbon dioxide produced by anaerobic digestion can be assimilated in the photobiofilm or directly through the growth of phototrophic organisms. This is facilitated by the growth of phototrophic organisms (e.g., cyanobacteria or purple bacteria) in the wastewater treatment plant, leading to the conversion of CO2 supplementation into organic carbon, resulting in further carbon sequestration.

[0064] The use of luminescent filaments helps overcome the resistance to light diffusion across the free surface of water, allowing for the growth of oxygen-producing photoheterotrophic biofilms in deep tanks. These biofilms can then be used to produce phototrophic particles. The luminescent filaments provide a medium in bioreactor processes that serves as both a carrier and a light source, optionally used in wastewater treatment plants or ponds.

[0065] Oxygen-producing phototrophic organisms that can exist in photoheterotrophic biofilms or phototrophic particles include, but are not limited to, microbial populations such as cyanobacteria, red and purple bacteria, eukaryotic algae, purple sulfur bacteria, various genera of cyanobacteria, and the growth of ice dust phototrophic particles.

[0066] The use of luminescent filaments allows for precise control of lux (luminescent energy). Lux control, optionally combined with control of the partial pressure of O2 and / or CO2 on the inner side of the gas transport membrane and / or the scouring energy on the outer side of the gas transport membrane, can be used to preferentially aid in the selection and growth of chosen biofilm-based photoheterotrophic organisms. Lux and gas (air / O2 and CO2) control strategies can optionally be used to help competitively grow biofilm-based populations such as cyanobacteria, red and purple bacteria, outperforming harmful growths such as algae (which are detrimental to scouring / mixing and light diffusion efficiency).

[0067] When combined with selective sludge disposal, the luminescent filaments, in addition to the phototrophic biofilm attached to the filaments, also allow the phototrophic particles to grow and bioaccumulate in the host water. The photoheterotrophic biofilm and phototrophic particles allow for the capture and promotion of more carbon for growth, redirection, and recycling.

[0068] In some instances, the device may have a biofilm support module. The module has luminescent filaments, optionally bundled around a core fiber. Multiple filaments may be encapsulated together in manifolds at both ends of the filaments. The luminescent filaments may be arranged as sheets within the module. Multiple modules may be arranged in a box configuration. The module may have a top manifold and a bottom manifold, each containing (optionally at the top of the gas delivery system) a set of light-emitting diodes (LEDs) to supply light along the luminescent filaments from bottom to top and / or from top to bottom, to diffuse lux to the biofilm growing and temporarily anchored to the outer surface of the luminescent filaments. Optionally, the module may have a mixture of luminescent filaments and gas delivery fibers (from 5% gas - 95% FO to 95% gas - 5% FO). The mixture of luminescent filaments and gas delivery fibers may be implemented at the system's cord, module, or box level.

[0069] The gas supply and control system can selectively supply air (oxygen) and / or CO2 to the gas transfer membrane. In some instances, at night, air (oxygen) is supplied to photoheterotrophic organisms for respiration via gas transfer fiber diffusion and / or fine bubble diffusion systems. During the day, CO2 from the host (free cultured biomass) is used as a carbon source, assimilated by the photo-oxygenated biofilm for growth, while oxygen is produced through photosynthesis enhanced by artificial (optionally including artificially concentrated natural sunlight) lux diffusion. In some instances, during the day, optionally, CO2 gas recovered from an anaerobic digester biogas system (30% v / v) or another carbon dioxide source is optionally purified and optionally enriched (e.g., to >90% v / v carbon dioxide) and supplied via the gas transfer membrane. Optionally, at night, air (oxygen) can diffuse through the gas transfer membrane to support the growth of phototrophic organisms. The growth of phototrophic organisms provides an easily assimilated carbon source, enhancing carbon capture. Gas recirculation systems can be used to control the levels of CO2 and O2 supplied to biofilms to levels that favor preferential growth and / or compete with harmful phototrophic populations (e.g., cyanobacteria may be preferred over eukaryotic algae). Flushing systems that use or reuse air, oxygen, or CO2 in the gas phase provide coarse bubble aeration, turbulence, and shearing to control the biofilm layer.

[0070] Optionally, the system or method further includes enriching the host (i.e., suspended) biomass using a phototrophic biofilm detached from the luminescent filaments and optionally generating phototrophic particles. The system and method can provide a composite biofilm-floc and particle bioreactor. Selective waste is used to retain and accumulate phototrophic particles in the system by means of a gravity selector. The combination of growing a biofilm on the luminescent filaments with the selective retention of phototrophic particles enables synergistic effects on particle size settling characteristics (to enhance the design and performance of separators such as settling tanks, filters, membranes, cloughs, flotation) and on the treatment and capture of organic matter (carbon, GHG, etc.).

[0071] In wastewater treatment, the combination of free-cultured (i.e., suspended) biomass with algae or other phototrophic organisms provides a comprehensive treatment solution. This combination of free host biomass and phototrophic organisms allows for wastewater treatment with carbon capture and recovery capabilities.

[0072] The conventional growth of phototrophic organisms is limited by light diffusion resistance because the use of photoheterotrophic organisms (such as algae) is typically implemented in long, shallow tanks (oxidation ditches or carrousels) in areas with abundant sunlight (such as the Maghreb, Middle East, Central America, SEA, etc.). Current solutions are limited to green space markets and sunny regions. Such solutions cannot be implemented in deep tanks (4, 5, 6, 8, or 10 m) widely used in wastewater treatment solutions. Furthermore, conventional bioreactors with a depth of 0.8 to 1 m can be 50 to 200 m long, resulting in an extremely large footprint. This remains a land-intensive solution. These limitations make this solution only suitable for new green space projects in deserts and remote areas. These limitations also hinder the use of conventional algae growth systems in existing brownfield wastewater infrastructure to provide a combination of suspended biomass and phototrophic organisms.

[0073] In some instances, the systems and methods described herein may have one or more uses or advantages, such as: a) overcoming light diffusion resistance and eliminating light diffusion bottlenecks encountered in deep-tank applications such as conventional activated sludge (CAS) or sequencing batch reactors (SBR); b) facilitating the growth of valuable photoheterotrophic populations; c) employing means such as lux and gas (air / O2 and CO2) control strategies to help compete with harmful growth such as algae (detrimental to flushing / mixing and light diffusion efficiency) to favor the growth of biofilm-based populations such as cyanobacteria, red and purple bacteria; d) increasing carbon capture for redirection with organic biofilms / phototrophic particles through CO2 assimilation (CO2 supplied by biogas reuse or other sources and / or obtainable from bacteria in the bulk mixed liquor used for WW treatment); e) enhancing the carbon sink from sludge treatment lines to phototrophic materials that can be reused in biogas or biopolymers / biodiesel; f) promoting biogas / biomethane production / recovery in biosolids treatment lines. g) Reduce greenhouse gas (GHG) emissions from wastewater treatment plants (WWTPs); h) Control the mixing requirements of cyanobacteria / algae / phototrophic particles; i) Utilize existing fine bubble aeration to provide oxygen for CO2 fixation; j) Allow the growth and extraction of bio-based polymers; k) Address the issue of the large footprint required by existing solutions due to shallow reactors (1m deep CAS oxidation ditch, SBR); l) Expand into the brownfield market; m) Enhance carbon / energy recovery; and e) Expand the market beyond sunny areas by addressing light diffusion resistance. Example

[0074] In laboratory experiments, bundles of 1 to 50 side-emitting optical fibers (SEFs) made of uncoated PMMA were directly connected to LEDs, or indirectly connected to LEDs via end-emitting sheathed fiber optic cables through 3D-printed adapters.

[0075] Qualitative observations were conducted on 0.5 mm SEF samples in untreated, sanded, kinked, stretched, and braided forms. Kinking and stretching moderately increased light transmittance and algal colonization compared to untreated fibers. Sanding produced the highest light emission and colonization. Braiding three fibers together also moderately increased light transmittance, but significantly increased algal colonization, particularly in the gaps of the braid.

[0076] In the comparative study, a 6-watt red LED (19,000 lux) was used to provide light to 30cm PMMA filaments of various diameters and configurations. The intensity of the light emitted from one side of the filament was measured at a distance of 15cm from the light source. The results are provided in Table 1 below. In the ring configuration, light is received at both ends of the filament, which can also be considered as representing that the module has light supplied from both the upper and lower manifolds. As indicated in Table 1, the output light intensity increases with the filament diameter, but the light intensity / cross-sectional area decreases with the filament diameter. Therefore, a group of multiple relatively thin filaments can be more efficient than a single thicker filament with an outer diameter equal to the combined outer diameter of these thinner filaments. Also as indicated in Table 1, the winding of the filament increases the output light intensity, which may be a result of one or more of the following: the bending of the wound fiber increases its output per unit length; or, the winding filament length per unit rope length increases. Under the conditions of this test, the ring configuration more than doubled the output light intensity, suggesting the benefit of providing light from both ends of the rope. The results in Table 1 are comparative, and the measured lux and PAR values ​​may underestimate the absolute values ​​because the photometer is not suitable for the surface of the cord.

[0077] Table 1 A portion of the annular and coiled device is inserted into a flask containing water. The water is inoculated with a mother liquor containing multiple microalgae strains collected from secondary effluent from a wastewater treatment plant. A biofilm containing the microalgae forms in the submerged section.

[0078] In another embodiment, a luminescent cord is fabricated by wrapping a 1.5m diameter 2.5mm PMMA filament with a 9m diameter filament as a winding thread around a 1.5m diameter 2.5mm PMMA filament core. The 1.5mm diameter filament wraps around the 2.5mm fiber approximately 1000 times, creating a pitch of approximately 1.5mm. The light emitted from the cord exceeds 10 PAR, which is expected to be sufficient to form an algal biofilm on the cord when it is immersed in wastewater and supplied with carbon dioxide. The carbon dioxide is either bubbled into the wastewater or supplied from a gas transport membrane near the cord, or added to the cord.

[0079] This written description uses examples to disclose the invention and is also intended to enable any person skilled in the art to practice the invention, including making and using any apparatus or system and performing any combined methods. The patentable scope of the invention is defined by the claims and may include other examples that would occur to those skilled in the art.

Claims

1. A module for supplying light to phototrophic organisms in water, the module comprising multiple luminescent filaments extending from at least one manifold.

2. The module according to claim 1, wherein the light-emitting filament is encapsulated in the manifold.

3. The module according to claim 1 or 2, wherein the light-emitting filament is combined with one or more hollow fiber gas transport membranes.

4. The module according to claim 3, wherein the luminescent filament and the hollow fiber gas transport membrane are combined in a cord.

5. The module according to any one of claims 1 to 4, wherein it has a light source inside or connected to the manifold.

6. The module according to any one of claims 1 to 5, wherein it has a gas source connected to the manifold.

7. A method comprising supporting a photobiotic biofilm on a module according to any one of claims 1 to 6, for example, wherein the module is inserted into a tank, which may be a treatment tank of a wastewater treatment system.

8. The method according to claim 7, the method further comprising growing suspended biomass in the tank.

9. The method according to claim 8, wherein the suspended biomass comprises phototrophic organisms.

10. A wastewater treatment system having a module according to any one of claims 1 to 6 inserted into a tank of water to be treated.

11. The system of claim 10, further comprising a secondary separation device to retain suspended biomass in the system.

12. The system of claim 11, further comprising a gravity selector.

13. An apparatus comprising, One or more luminescent filaments and one or more hollow fiber gas transport membranes.

14. The device according to claim 13, further comprising one or more inert or structural filaments.

15. The apparatus of claim 13 or 14, wherein one or more of the filaments are wound in a spiral around the other filaments.

16. A wastewater treatment method, the method comprising growing a phototrophic biofilm and growing non-phototrophic suspended biomass.

17. The method of claim 16, the method further comprising selecting and retaining particles containing phototrophic organisms.

18. The method of claim 16 or 17, the method further comprising supplying light to the photobiofilm from a luminescent medium immersed in a tank.

19. The method according to any one of claims 16 to 18, the method further comprising supplying carbon dioxide from an external source to the phototrophic biofilm.

20. The method of claim 19, wherein the externally sourced carbon dioxide is at least partially derived from anaerobic digester gas, optionally after a purification, concentration, or gas separation step.

21. The method according to any one of claims 16 to 20, wherein the non-phototrophic organism comprises heterotrophic denitrifying bacteria.

22. A wastewater treatment system comprising a phototrophic biological treatment tank, a non-phototrophic biological treatment tank, and a solid-liquid separation device, said wastewater treatment system being configured to provide sequential mainline treatment and to recycle sludge to said mainline treatment.

23. The system of claim 22, further comprising a gravity selector.

24. The system of claim 22 or 23, wherein the photobiotic treatment tank includes a luminescent medium immersed in the tank.

25. The system of claim 24, wherein the depth of the tank is at least 1 m, at least 2 m, or at least 3 m.

26. A light-emitting device comprising a) a plurality of side-emitting optical fiber cables and / or b) a side-emitting optical fiber cable wound around an additional filament.

27. The light-emitting device according to claim 26, comprising two or more side-emitting optical fiber cables twisted, wound or braided together.

28. The light-emitting device according to claim 26 or 27, wherein the side-emitting optical fiber cable comprises a PMMA filament.

29. The light-emitting device according to any one of claims 26 to 28, wherein the PMMA filament has a diameter in the range of 0.5 to 12 mm.

30. The light-emitting device according to any one of claims 26 to 29, further comprising a hollow fiber gas transport membrane.

31. The light-emitting device according to any one of claims 26 to 30, having an outer diameter in the range of 0.5 to 12 mm.

32. A wastewater treatment method, the method comprising immersing the apparatus according to any one of claims 26 to 31 in wastewater, supplying light to a side-emitting optical fiber cable, and supplying carbon dioxide to the wastewater.

33. The method of claim 32, wherein the carbon dioxide is supplied via a gas transport membrane.

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