Inlet water filtration system

Abstract

A filtration system produces filtered water and returns captured solids to source water. The filtration system includes a source water filter subsystem fluidly coupled to source water and at least one pump, the source water filter subsystem configured to receive a source water stream, capture organisms from the source water stream, and produce a filtered source water stream. The filtration system is configured to operate in a plurality of operating modes, wherein, in a first operating mode, the filtered source water stream is received from the source water filter subsystem along a first fluid pathway to produce filtered water at a first system outlet, and in a second operating mode, the filtered water stream is provided to a second fluid pathway and a second system outlet to flush captured organisms back to the source water and maintain a source water environment.

Description

[0001] Cross-reference to related applications This application claims priority to U.S. Provisional Application No. 63 / 599,515, filed November 15, 2023, entitled “Inlet Water Filtration System with Self-Cleaning Device,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention relates to a system and method for filtering solids from a source water stream. Background Technology

[0003] The United States has an abundant supply of freshwater (reservoirs, lakes, and rivers) and virtually unlimited seawater (ocean) for future use in supplying drinking water, agriculture, cooling, energy production, manufacturing, and other water-intensive processes. However, habitats continue to be at risk as coastal facilities draw in water. This high environmental cost is largely due to the fact that most water intake methods rely on conventional technologies that result in the death of all entrained life forms, including plankton, eggs, larvae, and juveniles. While newer technologies such as self-cleaning filters and underground wells may offer improvements, little is known about their impact on plankton and benthic organisms. Even the California Ocean Plan Amendments (OPA), often considered the gold standard for marine conservation, assumes a 100% mortality rate for entrained organisms in its regulatory guidance on open water intake screening and recommends underground wells as the preferred technology—a more costly, size-limited, and site-constrained method.

[0004] For intake systems crucial to various applications such as desalination and power generation, water sources have traditionally been derived either directly from surface water bodies such as oceans, lakes, and rivers (open intakes) or from underground wells (subsurface intakes). While open-water methods are more common, they pose significant risks to the environment, particularly to marine organisms that may become trapped or unintentionally killed during fishing. Subsurface methods are less harmful to marine life. Nevertheless, they disrupt benthic ecosystems and groundwater supplies, are energy-intensive, and are geographically and environmentally limited, making them less adaptable and more costly in the long run. Furthermore, submersible feedwater intake systems that draw in fresh, brackish, or saline water, such as wedge-shaped wire mesh systems, typically require routine maintenance to remove impacted organisms, debris, or other particulate matter that may clog the intake surface; and to remove organisms, organic or inorganic fouling that may clog any or all intake surfaces or support structures.

[0005] To address these challenges, a range of technologies have been developed to reduce the environmental impact of open intake systems. These include advanced screen designs designed to minimize the capture of marine organisms and automated cleaning systems that help maintain screen efficiency and lifespan. Despite these improvements, all cleaning methods have limitations; some may harm marine organisms or require significant energy and maintenance. Furthermore, current intake systems inevitably cause some death of small organisms passing through, leading to further environmental problems. Intake water typically undergoes a series of pretreatment processes to ensure its cleanliness and safety for its intended use. These processes often involve chemicals and physical filters, which, while effective, also have their own environmental and spatial footprints. Summary of the Invention

[0006] In some embodiments, a filtration system is disclosed for generating filtered water and returning captured solids to source water. The filtration system includes: at least one pump; an inlet filter subsystem fluidly coupled to source water and the at least one pump, configured to receive a source water flow, capture organisms from the source water flow, and generate a filtered inlet water flow. The filtration system is configured to operate in multiple operating modes, wherein in a first operating mode, the filtered inlet water flow is received from the inlet filter subsystem along a first fluid passage to generate filtered water at a first system outlet; and in a second operating mode, the filtered water flow is provided to a second fluid passage and a second system outlet to flush the captured organisms back to source water.

[0007] In another embodiment, a multi-stage filtration system is provided for generating filtered water and returning captured solids to source water. The multi-stage filtration system includes at least one pump; an inlet filter subsystem fluidly coupled to the pump and configured to receive a source water flow and filter organisms from it; and a self-cleaning subsystem coupled to the inlet filter subsystem and configured to periodically remove organisms from the inlet filter subsystem and displace them into the gap space between successive filters of the inlet filter subsystem. The multi-stage filtration system is configured to operate in multiple operating modes, wherein in a first operating mode, the inlet filter subsystem receives a source water flow to generate a filtered water flow along a first fluid path; in a second operating mode, the filtered water flow is provided to the gap space and flows along a second fluid path spanning a downstream filter face and an upstream filter face of the successive filters, returning the organisms to the source water through the outlet of the multi-stage filtration system.

[0008] A method for generating filtered water and returning captured solids to source water is also disclosed. The method includes operating a multi-stage filtration system in a first operating mode to receive a source water flow along a first fluid passage and generate a filtered water flow at a first system outlet. The first fluid passage includes a plurality of progressively narrowing filters configured to remove biological material from the source water flow. The method further includes operating the multi-stage filtration system in a second operating mode to direct the filtered water flow along a second fluid passage to a second system outlet, returning the biological material to the source water. The second fluid passage includes gap spaces between successive filters and flows across downstream and upstream filter faces of the gap spaces to the second system outlet. Attached Figure Description

[0009] Figure 1 This is an example of a filtration system according to the present invention for generating filtered water and maintaining the source water environment.

[0010] Figures 2A-2B The water inlet event or first operating mode of the filtration system according to an example of the present invention is shown.

[0011] Figures 2C-2G A filtration system with a self-cleaning subsystem according to an example of the present invention is illustrated schematically.

[0012] Figures 2H-2J A side view schematically illustrates an example of a backwashing or backflushing operation mode according to the present invention.

[0013] Figures 3A-3B A filtration system according to an example of the present invention is illustrated schematically.

[0014] Figures 4A-4B A filtration system according to an example of the present invention is illustrated schematically.

[0015] Figures 5A-5B A filtration system according to an example of the present invention is illustrated schematically.

[0016] Figures 6A-6C A filtration system with multiple concentric cylindrical filters according to an example of the present invention is illustrated schematically.

[0017] Figure 7 A flowchart illustrating the multi-stage filtration system disclosed in the example according to the present invention and the conventional submersible water inlet system is shown schematically. Detailed Implementation

[0018] The expression of a numerical range using endpoints includes all numbers contained in that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0019] The terms “a,” “an,” “the,” “at least one,” and “one or more” are used interchangeably. Thus, for example, a device that includes a “reverse osmosis membrane” includes “one or more” such membranes.

[0020] When used in the context of a pattern or event, the term "backwashing" refers to the flow of filtered water through a flow path to discharge suspended solids and organisms from one or more gaps in the flow path into a collection system or source water.

[0021] The term "backwash" refers to a combination or sequence of cleaning or backwashing modes to remove solids and organisms from one or more filters and flush them into the collection system or source water.

[0022] The term "brine" refers to an aqueous solution containing a higher concentration of sodium chloride than typical brine, specifically a salinity greater than approximately 3.5% sodium chloride. It should be noted that different jurisdictions may use different definitions for the term "brine" or may impose different limits on brine discharge. For example, under current California regulations, discharge should not exceed a daily maximum of 2.0 parts per thousand (ppt) above the natural background salinity, measured horizontally at a distance of no more than 100 meters from the discharge point. In other jurisdictions, salinity limits may be set at levels such as 1 ppt above the environment, 5% above the environment, or 40 ppt above the environment.

[0023] When used in the context of patterns or events, the term "cleaning" refers to the physical process of removing impacted material from one or more filters using brushes, sprayers, air bursters, back pressure, or other such techniques.

[0024] The term "concentrate" refers to a desalination plant discharge stream with a higher salinity level than the surrounding seawater, but not necessarily containing sufficient salinity to qualify as brine in the applicable jurisdiction where such a stream is produced.

[0025] The term "conduit" refers to a tube or other hollow structure (e.g., orifice, channel, pipe, hose, line, opening, passage, riser, tube, or well) through which liquid flows during the operation of a device using such a conduit. The cross-section of a conduit may be, but is not necessarily, circular; it may have other cross-sectional shapes, including elliptical or other near-circular or semi-circular, triangular, square, rectangular, or other regular or irregular shapes. A conduit may also be, but is not necessarily, linear or uniform along its length, and may have other shapes, including tapered, spiral, or branching (e.g., branches radiating outwards from a central hub).

[0026] When used for submersible devices or components thereof, the term “depth” refers to the vertical distance, that is, the height of the water column from the free surface of the water body of the submersible device or component to the location where seawater is introduced into the device or component.

[0027] The terms “desalinated water,” “fresh water,” and “product water” refer to water containing less than 1,000 ppm, more preferably less than 500 ppm, of dissolved inorganic salts by weight. Exemplary examples of such salts include sodium chloride, magnesium sulfate, potassium nitrate, and sodium bicarbonate.

[0028] When used in filters having an upstream face, a downstream face, and a channel between the upstream and downstream faces, the term "flow through" refers to flow along the filter surface rather than through the filter channel, where the filtrate can flow through the filter while the filtrate can be trapped in the filter.

[0029] The term "fluid passage" refers to a conduit, filter, gap space, or pump that allows fluid to move in a selected direction. The terms "first fluid passage" and "second fluid passage" refer to different fluid passages (but may include some common path elements), distinguished not only by the fact that the same path elements have different fluid flow directions along them.

[0030] The term "gap space" refers to the fluid flow path across the filter surface between the downstream side of the upstream filter and the upstream side of the downstream filter.

[0031] For the purposes of this disclosure, the terms "living matter" and "organism" are interchangeable and refer to organic matter containing nucleic acids and capable of evolution. An organism can be a microorganism, a single-celled or multicellular organism, including planktonic, swamous, and benthic organisms that may be captured, trapped, carried or impacted by the filtration of source waters to the seabed.

[0032] The term "microorganism" refers to an organism that can only be seen through a microscope.

[0033] When used to refer to suspended pollutants, the term "particulate" refers to particles with a size of 1 micrometer to 5 millimeters.

[0034] When used in filtration systems, the term "multi-stage" refers to a system that includes two or more filters arranged in series and has progressively smaller filter channels.

[0035] The term “at sea” means equipment, systems or methods located at or performed at sea, or located at or performed at a distance from the coast.

[0036] The term "land-based" refers to equipment, systems, or methods located on or performed on land.

[0037] The term "platform" refers to a supporting surface for equipment installation, which is typically horizontal and flat and usually elevated relative to the surrounding environment. In some embodiments, an offshore platform may be non-horizontal, non-flat, or partially or fully submerged.

[0038] The term "seawater" refers to water with a dissolved inorganic salt content exceeding 0.5 ppt by weight, and therefore includes brackish water (water with a dissolved organic salt content of 0.5 to 3.0 ppt by weight) as well as ocean water or other water with a dissolved organic salt content exceeding 3.0 ppt by weight. In the ocean, dissolved inorganic salts are typically measured based on total dissolved solids (TDS), which is usually around 35 ppt TDS on average, although local conditions can cause salinity to increase or decrease.

[0039] The term "solids" refers to water-insoluble substances, including living matter, particulate matter, suspended matter, dirt, debris, or debris that may be captured, trapped, entrained, or impacted by the filtration of source water into the seabed.

[0040] The term "immersion" refers to underwater.

[0041] The term "submersible" means suitable for use during immersion and primarily for use during immersion.

[0042] The term "top side" refers to the area above the surface of a body of water, such as the sea level of an ocean.

[0043] In one example, a self-cleaning and life-friendly filtration system and method are disclosed. The filtration system may include a pump, a self-cleaning subsystem, an inlet filter subsystem, and multiple fluid passages for generating filtered water and returning captured solids to the surrounding water body.

[0044] However, while the return of captured solids may be a feature of the disclosed filtration system, it should be understood that the system may also be beneficial in various other respects. For example, even in environments where there are no significant amounts of solids, such a filtration system can provide an efficient and effective method for producing filtered water, allowing for on-site maintenance and longer uptime. However, if organisms are present, the system may produce filtered water without significantly killing captured organisms, impacting larger organisms, entraining smaller organisms, or disrupting the surrounding environment and benthic communities. This, in turn, may lead to better environmental outcomes at both the inlet and final discharge points. Furthermore, such a filtration system can reduce the cost, energy demand, and environmental impact of natural inlets, including those supplying desalination and water purification facilities, which in turn increases water supply flexibility and adaptability in the face of long-term climate change and short-term drought risks. This can further allow for the acquisition and delivery of cleaner water from unavailable water sources without the need for extensive pretreatment, chemicals, and land.

[0045] The filtration system and method described herein can operate in any quantity of source water, with or without solids. These sources may include seawater, ocean, bay, bend, estuary, reservoir, lake, river, or pond water. Specifically, these sources may include the 338 reservoirs operated by the U.S. Bureau of Reclamation (>140 million cubic feet), the Great Lakes (>18 billion cubic feet), the Colorado and Mississippi Rivers (>1 billion cubic feet / year), the Gulf of Mexico, the Atlantic and Pacific Oceans (with virtually unlimited capacity), and numerous natural bodies of water within U.S. territory and at military bases worldwide, where suitable nearshore / coastal areas are suitable for the filtration system. Furthermore, it should be understood that this system can operate in any body of water. For example, this may include onshore or offshore waters in Australia, the United States, the Mediterranean Sea, the Indian Ocean, etc. Additionally, in one example, the system can be used at a depth of at least approximately 200 meters below the surface of the seabed. For example, in dark areas, depths of 200-1000 meters may be ideal. Compared to source water in light-filled areas near the surface, dark areas are typically darker, colder, clearer, with lower particle counts / turbidity and less biological activity. However, it should be understood that these are merely examples, and filtration systems can produce filtered water at almost any depth in virtually any body of water, from freshwater to brackish water to saltwater.

[0046] In addition to supplying coastal facilities and submerged processing plants, filtration systems and methods can also supply filtered water to offshore facilities such as seabed desalination, marine thermal energy conversion, marine carbon capture, offshore hydrogen production, seawater extraction, pollution cleanup, ecosystem restoration, and other current and future innovations in the growing marine economy. Furthermore, this filtered water can be provided for irrigation operations and water-intensive industrial processes such as mining, oil and gas, semiconductor manufacturing, or textile manufacturing. Further applications of filtered water may include providing cooling systems for power plants, data centers, or civil infrastructure. However, it should be understood that these are merely examples, and other applications and processes may utilize the disclosed filtration systems.

[0047] Figure 1This is an example of a filtration system for generating filtered water and maintaining a source water environment according to the present invention. As shown, the filtration system 100 includes a reversible pump 102, a self-cleaning inlet filter subsystem 104, an inlet / outlet 106 coupled to the reversible pump 102, and a life-friendly return outlet 108. In operation, the filtration system 100 can operate in different operating modes to generate filtered water (inlet mode) and maintain a source water environment (backwashing mode and backflushing mode). In one example, in a first inlet operating mode, the reversible pump 102 can draw a source water flow containing solids 110 along a first fluid passage 112 via the self-cleaning inlet filter subsystem 104 to generate filtered water or supply water 114 through outlet 106. In a second, backwashing or backflushing operating mode, the reversible pump 102 can operate in reverse to drive the filtered water or supply water 114 along a second fluid passage 116 through the life-friendly return outlet 108, thereby returning any captured solids to the source water. By returning the captured solids, the source water environment can be maintained. In another embodiment, non-living solids (e.g., microplastics and other particles) can be separated from organisms in the collected solids by means of the apparatus and techniques described in detail in a co-pending international application (Patent Agent No. 40031-157) filed on the same day entitled “Pollution Cleanup Using an Immersion Filter Device”, the disclosure of which is incorporated herein by reference.

[0048] In some embodiments, the filtration system 100 preserves a thermophysicochemical environment for resident organisms to interact with the system. The system 100 can operate without the use of chemicals and under conditions close to ambient pressure, salinity, temperature, and dissolved gas concentrations. Furthermore, as shown, a reversible pump 102 can be located downstream of all filtration stages, preventing entrained organisms (up to a selected discharge size) from passing through the pump impeller.

[0049] One or more pumps, such as pump 102, may be located upstream or downstream of the first and second filtration stages or any other downstream process (e.g., reverse osmosis). In operation, pump 102 may generate a pressure differential through the filtration system 100 in a first operating mode to draw in unfiltered source water and drive it to flow in a generally vertical manner onto the surfaces of each filtration stage. The geometry of the pump impeller, shroud, and blades may be designed to adjust pump performance and efficiency as needed to optimize flow rate and avoid undesirable effects such as turbulence, cavitation, backflow, vortices, eddies, or other disturbances. Depending on the required volume, pressure, and specific velocity of the chosen application, the type of pump (e.g., axial pump vs. mixing pump vs. centrifugal pump) and its efficiency (e.g., specific energy) may be highly scale-dependent.

[0050] When pump 102 draws in unfiltered source water along the first fluid passage 112, any number of fluid-coupled stages along passage 112 can be used to filter solids. For example, system 100 may include three filtration stages, where the opening size of the first stage is larger than the opening sizes of the second and third stages. Conversely, the opening size of the second stage may be larger than the opening size of the third stage, but smaller than the opening size of the first stage. In this example, as fluid travels along path 112, progressively smaller particles and organisms can be captured along passage 112 before downstream processes (e.g., subsea reverse osmosis processes).

[0051] Furthermore, in one example, the reversible pump 102 can pump source water through a multi-stage filtration system (in a first forward operating mode) and push filtered water through a backwash or reverse flushing system (in a second reverse operating mode). In this example, in the first operating mode, a low approach velocity (below the EPA or U.S. Environmental Protection Agency recommendation of 0.5 feet per second) can be maintained by increasing the outermost screen size of the inlet filter subsystem 104 to eliminate the impact of larger organisms on the filter surface (e.g., fine wedge grooves, below the EPA recommendation of 1 mm or less). This is feasible because system 100 can operate submerged in water, thereby relaxing land-use-related size restrictions and preventing pump cavitation. Additionally, submersion in the mid-water layer, sufficiently below the water surface and above the seabed, may reduce impacts on benthic communities and protect them from atmospheric and climate risks such as drought, flooding, sea-level rise, and extreme weather. Compared to biological activity in the water column, the mid-water submersible operation of System 100 also minimizes scaling and influent quality issues associated with surface and bottom events, such as algal blooms, turbidity, and suspended / dissolved contaminants that typically sink or rise when released into natural water bodies.

[0052] Although the first and second flow paths are discussed below, it should be understood that such flow paths can be discretely defined regions through which source water, interstitial water, and filtered water can pass. These paths can be selected based on the operating parameters of system 100. For example, a first operating mode can initiate a forward fluid flow through system 100, while a second mode reverses the flow to induce a backwash or backflushing event, returning captured solids. Each flow path can be arranged in the form of an interconnected network of pipes or other volumetric spaces fluidly connected to each other but separated by filters, valves, or pumps, so that solids can be discharged, backflushed, or flushed out of the system during a backwash or backflushing event. Flow paths can have one or more inlet or outlet regions through which fluid can enter or exit the interstitial spaces during a backwash or backflushing event.

[0053] Figures 2A-2BThe water inlet event or first operating mode of the filtration system according to an example of the present invention is illustrated. Specifically, Figure 2A A side view schematically illustrates an inlet water event that generates filtered water. As shown, the filtration system 200 includes an inlet filter subsystem 202 with multiple filter (stages) 204 and 206, a valve subsystem 222 with a valve 214, and at least one pump 210. A gap space 208 is located between filters 204 and 206, defining a fluid flow path across the filter surface between the downstream side of the upstream filter and the upstream side of the downstream filter. In operation, the inlet filter subsystem 202 may be supported by a support structure (not shown) or load-bearing member supporting the first and second filter stages, and may be fully or partially integrated with or separated from the filter media, thereby allowing for easy maintenance or replacement of these structures.

[0054] As shown in the figure, in a first operating mode, one or more pumps 210 can draw source water flow along a first fluid passage 212 to produce filtered water. In one example, the first fluid passage 212 is defined by a pressure differential generated by pumps 210, wherein the source water flow moves through one or more filter stages having one or more gap spaces to produce a filtered water flow. Specifically, as the source water flow travels along the first fluid passage 212, filters 204 and 206 can allow the source water to be continuously filtered along the passage 212 to produce filtered water. The filtered water can then be discharged or supplied to additional downstream applications, such as desalination tanks, outlets, etc.

[0055] In one example, when the source water flows into the first stage (e.g., filter 204), its approach velocity can be kept below the critical impact velocity, for example, less than 0.5 feet per second, to comply with EPA guidelines. Furthermore, it is conceivable that the approach velocity of the interstitial water leaving the first stage (e.g., filter 204) and entering the second stage (e.g., filter 206) can be greater than the velocity of the feed water entering the first stage, for example, greater than 0.5 feet per second.

[0056] Filter 204 may have a coarser porosity or a larger opening size than filter 206, or in other words, filter 206 may have a finer porosity or a smaller opening size than filter 204. While two filters are shown as an example, it should be understood that system 200 may include any number of additional filtration stages, such as a third filter, a fourth filter, a reverse osmosis membrane, etc., located downstream or upstream of stages 204 and 206. Each successive filtration stage may be assembled in series to filter out progressively finer solids with minimal induced pressure drop, while the gap space between adjacent filtration stages remains fluidly coupled to a common discharge outlet to remove entrained, displaced, and suspended solids during backwashing or backflushing events.

[0057] In operation, each filtration stage, from the external upstream stage to the internal downstream stage, may contain progressively smaller openings, pore sizes, channel widths, or channel dimensions to filter out progressively smaller solids. The nominal opening size of each stage may vary and depend on the locally unregulated feedwater characteristics and the ultimately regulated feedwater quality target. For example, a first wedge-shaped wire mesh with 500µm openings and a second woven fabric with 50µm openings can deliver a specified quality of feedwater to the downstream subsea reverse osmosis process. Furthermore, the size of the total opening area and surface area of ​​each filtration stage can minimize pressure drop, which can typically be kept below the feedwater pressure drop limits of the downstream pump or process.

[0058] Each filtration stage can be in the form of 3D printed material, a flat plate, concentric cylinder, or other flat, curved, or pleated surface with openings, such as wedge-shaped wire mesh, fabric, felt fabric, or other perforated filters, structural or particulate media, such as filled sand, gravel, anthracite, or other mechanically, chemically, electromagnetically, or biologically selective or non-selective depth or surface filtration materials. However, surface filtration mechanisms, such as screens or fabrics, may be preferred. Each stage and its corresponding support structure may also comprise a single material or a combination of the following materials: metal, plastic, composite material, textile, fabric, glass, or other extruded, woven, pleated, machined, additive-manufactured, porous, floating, artificial, or natural materials.

[0059] As shown in the figure, the gap space 208, located between filters 204 and 206, serves as a trapping area. In this trapping area, solids smaller than the opening size of filter 204 but larger than the opening size of filter 206 are entrained, suspended, or impacted onto the outer surface of filter 206. The gap space 208 can be opened or closed at either the first or second end of the fluid passage. This open end can be in fluid communication with a second fluid path to allow solids from the gap space to be flushed out of the space and discharged into open water or supplied to a secondary downstream process.

[0060] In the first operating mode, valve 214 can also be in the closed position. However, as Figure 2B As shown, according to the present invention, the valve subsystem 222 may further include a second valve 216 or any number of valves. In one example, when the pump (e.g., pump 210) operates in the first inlet operating mode (forward), the valve subsystem 222 restricts the flow through the filtration system. In the second, backwashing or backflushing operating mode, when the pump (e.g., pumps 210, 308, 402, 502, 612) operates in the reverse direction or the second pump (e.g., pumps 404, 504) or the third pump (e.g., pump 506) operates in the forward direction, the valve subsystem 222 may allow interstitial water to backwash or backflush from the interstitial space (e.g., Figures 2C-2J , Figure 3B , Figure 4B , Figure 5B and Figure 7 (As shown) and flow backwards. Furthermore, in the second operating mode, valve subsystem 222 can prevent source water from entering interstitial water or filtered water. This also prevents interstitial water from entering along with filtered water. The valves of valve subsystem 222 can be passively, automatically, or manually controlled by several different valve mechanisms (e.g., check valves, duckbill valves, Tesla valves, sleeve valves, piston valves, etc.) with or without moving parts.

[0061] In some examples, such as Figures 2C-2G As shown, the filtration system 200 may also include a self-cleaning subsystem 218, 230, 232, 234, or 236 coupled to the inlet filter subsystem 202 to manage fouling, extend the lifespan of the system 200, and capture solids 238 within the system 200. As will be discussed below, the self-cleaning subsystems 218, 230, 232, 234, or 236 may include any combination of automatic cleaning devices to gently and thoroughly clean clogged screens and filters, thereby safely removing impacted solids. In turn, during a backwash or backflushing event, these captured solids can be gently discharged from the system 200 without harm. In one example, this may result in organisms captured within a selected discharge size not dying. However, in other examples, backwashing or backflushing organisms into the source water may result in at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 99% of the living organisms returning to the source water.

[0062] For example, such as Figures 2C-2G As shown, the filtration system 200 may include self-cleaning subsystems 218, 230, 232, 234, or 236 coupled to the inlet filter subsystem 202 for removing and displacing solids from one or both of filters 204 and 206. Although Figures 2C-2G Self-cleaning subsystems 218, 230, 232, 234, and 236 are illustrated exemplarily in a second operating mode (e.g., cleaning, backwashing, or backflushing operating mode), but it should be understood that self-cleaning subsystems 218, 230, 232, 234, and 236 can also operate in a first operating mode (normal water inlet event). Furthermore, as... Figure 2C and Figure 2F As shown, self-cleaning subsystems 218 and 234 can be fixedly arranged on filter 204. Alternatively, as Figure 2D and Figure 2F As shown, self-cleaning subsystems 230 and 234 can be arranged on filter 206, or as... Figure 2E and Figure 2GAs shown, it is arranged within the gap space 208. The self-cleaning subsystem 218 may include any number and type of brushes, blades, sprayers, or air bursting devices to safely capture solids within the gap space 208 while cleaning the inner or outer surfaces of one or more filters (e.g., filters 204 and 206). In operation, such a module may clean and contact only one filtration stage, such as... Figure 2C and Figure 2D As shown, it can also clean and contact multiple filter stages simultaneously (such as...). Figure 2E , Figure 2F and Figure 2G (As shown). Furthermore, as... Figure 2F As shown, any combination of these modules can be used. For example, such as Figure 2F As shown, subsystem 234 may include: a brush configured to clean the outer surface of the second filtration stage; and a water sprayer configured to spray the inner surface of the first filtration stage. It should be understood that any combination, number, and type of cleaning modules can be used in this invention.

[0063] In some examples, such as Figures 2C-2G As shown, the self-cleaning subsystem 218 can also be passively or actively driven by a drive mechanism (not shown) to rotate along the cleaning axis, for example... Figure 2G The shaft 228 is shown. For example, a drive mechanism may be needed to transmit motion to the self-cleaning subsystem 218 to thoroughly clean each filtration stage. The drive mechanism may include any number of drive chains or belts, motor drive gears, screen gearboxes, motors, etc., to cause rotational or translational motion of filters 204 and 206 and the passive or active self-cleaning subsystem 218, for example... Figure 2G Movement 226 within the filters. This ensures that all or substantially all captured solids are safely removed from filters 204 and 206 and suspended within the gap space 208. In one example, the active drive motion of one or more filters can passively drive subsystems 218, 232, and 236. Specifically, the drive mechanism may include a transmission chain coupled to one or more filters to actively transmit motion to the filters. In turn, as the filters rotate, the cleaning modules of subsystems 218, 232, and 236 coupled to the filters can passively rotate to ensure proper and adequate cleaning.

[0064] After, before, or during an influent or cleaning event, a backwash or backflushing event can be performed in a second operating mode to safely return captured solids to the source water. According to this disclosure, it should be understood that system 200 may include unique selections of optimized flow paths, pressures, times, and compatible materials to minimize contact, turbulence, pressure, shear, and osmotic stresses known to cause the death of entrained organisms in backflushing and backwashing operating modes. Furthermore, while in forward operation the pump can draw water in through the inlet and extract water from the drain riser, in the second operating mode, the riser volume can determine how much filtered water is available for the backwash or backflushing event. Therefore, it is conceivable that any number of different risers can be used to supply the required amount of filtered water.

[0065] Figures 2H-2J A side view schematically illustrates an example of a backwashing or backflushing event (second operating mode) according to the invention. Figures 2H-2J As shown, in a backwash or backflushing event, one or more pumps 210 can operate in reverse to displace the filtered water along the second fluid passage 220, thereby returning the captured solids to the source water. In one example, when pump 210 operates in reverse, as... Figure 2H and Figure 2I As shown, one or more valves 214 and 216 can be opened to allow filtered water to pass through the second fluid passage 220. Figure 2H and Figure 2I As shown, the second fluid passage 220 may include a gap space 208 and a channel leading to a discharge outlet (not shown) to return captured solids to source water, a collection container, or other downstream equipment. Returning captured solids to their natural environment mitigates and avoids potential environmental damage. The second fluid passage 220 may be defined by a reverse pressure differential generated by pump 210 or an optional second pump, in which filtered water moves in a substantially opposite direction to the first flow path in the first operating mode. In one example, this creates a reverse pressure differential to backwash or flush filtered water, source water, or gap water from an upstream filtration stage (or from the original source) to the discharge outlet.

[0066] Figures 3A-3B A filtration system according to an example of the present invention is illustrated schematically. For example... Figure 3A As shown, the filtration system 300 includes an inlet filter subsystem 302 with multiple filters 304 and 306, a pump 308, a flow regulator 310, a flow restrictor 312, and a valve subsystem 314 with valves 316 and 318. In the first operating mode (inlet event), as... Figure 3AAs shown, the source water flow can travel along the first fluid passage 320 to the forward-operating pump 308. As the source water travels along the fluid passage 320, filters 304 and 306 allow for continuous filtration of solids from the source water to produce filtered water. Furthermore, the flow regulator 310 can uniformly distribute the first flow path 320 across the porous surfaces of filters 304 and 306, and deliver the resulting filtered feed water flow to secondary downstream processes, such as subsea reverse osmosis.

[0067] In the second operating mode, such as Figure 3B As shown, valves 316 and 318 can be opened, and pump 308 operates in reverse to drive filtered water or source water through flow restrictor 312 along the second fluid passage 322, thereby creating a pressure drop. Flow restrictor 312 can partially contract and then rapidly expand the fluid passage 322 to accelerate the fluid velocity near the gap flow passage, causing the increased fluid velocity to result in a pressure drop and corresponding gap flow along path 322, similar to the mechanism of a Venturi-type or Pitot-type flow restrictor. Furthermore, flow regulator 310 can regulate the path 322 toward the discharge outlet in one of two directions, either via filter 306, flow restrictor 312, or, in some examples, via a second pump. The filtered gap water can then flow along the second fluid passage 322 to the source water.

[0068] Figures 4A-4B A filtration system according to an example of the present invention is schematically illustrated. As shown, filtration system 400 includes components similar to those of filtration system 300, but has multiple pumps 402 and 404. In a first operating mode, as... Figure 4A As shown, pump 402 can operate in the forward direction, and pump 404 is off. In this example, the source fluid flow can pass through each filtration stage along the first fluid passage 406, generating filtered water flow. Alternatively, in the second operating mode, as... Figure 4B As shown, pump 402 can operate in reverse or off, and pump 404 is activated to generate a pressure drop and drive filtered water or source water and interstitial water to the source water along the second fluid passage 408. Furthermore, in this example, valves 410 and 412 can be closed in the first operating mode, while valves 410 and 414 can both be opened in the second operating mode.

[0069] While pump 402 can be driven in either forward or reverse, it is also conceivable that in other examples, pump 402 can be driven in the forward direction or shut off during the first and second operating modes, respectively. In this example, only pump 404 can be used in the second operating mode to generate a pressure drop and to flow the corresponding filtered water and interstitial water to the source water.

[0070] Figures 5A-5BA filtration system according to an example of the present invention is schematically illustrated. In this example, the filtration system 500 includes a plurality of pumps 502, 504, and 506 and a valve subsystem 508. Although the valve subsystem 508 exemplary includes two valves 510 and 512, any number of valves can be used. In a first operating mode, such as Figure 5A As shown, pump 502 can operate in the forward direction to draw in source water along the first fluid passage 514 and produce filtered water. Conversely, the filtered water can be supplied to any number of downstream processes, such as to the source water. In this example, valves 510 and 512 can remain closed, while pumps 504 and 506 remain closed. In the second operating mode, as... Figure 5B As shown, pump 502 can be shut off or operated in reverse, valves 510 and 512 open, and pumps 504 and 506 open to direct the filtered interstitial water flow to the source water along the second fluid passage 516. In this example, pump 504 can redirect the filtered water flow to an outlet, while pump 506 generates a pressure drop to direct the interstitial water flow to the same or a different outlet.

[0071] Figures 6A-6C A filtration system with multiple concentric cylindrical filters according to an example of the present invention is illustrated schematically. Figures 6A-6B As shown, the filtration system 600 includes a pump 612, check valves 616 and 624, a flow regulator 626, and a plurality of concentric cylindrical filters 602, 606 for producing filtered water. While the system 600 exemplary includes two concentric cylindrical filters 602 and 606, it should be understood that any number of concentric filters can be used. In a first operating mode, as... Figure 6A As shown, pump 612 can draw source water along the first fluid passage 614 into each cylinder 602 and 606 to produce filtered water. In turn, the filtered water can be supplied to flow regulator 626 and any number of downstream processes, such as desalination, filtration, etc. In the second operating mode, such as... Figure 6B As shown, pump 612 can operate in reverse to drive filtered water along a second fluid passage 624 through open valve 624, channel 622, the gap space between cylindrical filters 602 and 606, and valve 616 to return captured solids to the source water. While valves 616 and 624 are closed in the first operating mode, they can be opened in the second mode. In one example, valve 616 may include a one-way valve mechanism near the end of the second flow passage to flush suspended particulate matter and organisms from the gap space when closed and to restrict unfiltered feedwater from entering the gap space. Furthermore, in this example, when opened during a cleaning event, the valve mechanism may allow backflow of gap feedwater driven by downstream suction pressure. This may allow for an additional level of redundancy to restrict source water from entering through the discharge outlet during the first operating mode.

[0072] Figure 6C It shows Figures 6A-6B A cross-sectional view at point AA. As shown, the concentric cylinder 602 allows source water to enter at any point surrounding or enclosing the cylinder 602 along the first fluid passage 614. In this example, a continuous flow of source water can be received at any point around the system 600 and used to produce filtered water.

[0073] Figure 7 A flowchart schematically illustrates the disclosed multi-stage filtration system and a filtered feedwater system with only one filter at the pump inlet, comparing the results of impacted and entrained solids that may enter the downstream pretreatment process. As shown, the multi-stage filtration system 700 of this disclosure may include multiple filtration stages 716, 718, 720, 722 located upstream of a reversible pump 724 to receive source water flow 704 along a fluid passage 740 and filter out solids 712 to produce filtered water 706. In a first operating mode, solids 712 can be impacted or trapped because each stage 716, 718, 720, and 722 includes a finer porosity or smaller opening size than the previous stage. For example, the first stage 716 may prevent the passage of solids 712 larger than 1 mm, the second stage 718 may prevent the passage of solids larger than 100 µm, the third stage 720 may prevent the passage of solids larger than 10 µm, the fourth stage 722 may prevent the passage of solids larger than 1 µm, and so on. According to this disclosure, it should be understood that any number of different stages or filters with reduced opening size or porosity can be used.

[0074] When solids 712 are impacted or trapped between filters 716, 718, 720, and 722, a self-cleaning subsystem 726 coupled to each filter 716, 718, 720, and 722, such as a brush, sprayer, air jet, etc., can operate in cleaning mode to remove the impacted solids 712 into the gap space between each filter 716, 718, 720, and 722. Conversely, pump 724 can operate in reverse during backwashing or backflushing operation mode to direct filtered water flow 706 through one or more internal channels fluidly coupled to each gap space and a life-friendly return outlet, while safely returning the trapped solids 712 to source water 704. As a result, a significant portion (e.g., at least 50%, at least 60%, at least 70%, at least 80%, or at least 90%) of the trapped solids 712 can be safely returned to source water 704.

[0075] Systems such as the submersible inlet system 702 may also include multiple filtration stages 730, 734, 736, and 738, and a reversible inlet pump 732 fluidly coupled between stages 730 and 734 for generating a filtered water flow from source water 708 along a fluid path 742. System 702 captures large organisms 744 at filter stage 730. When cleaning of stage 730 is required, reversing pump 732 provides a single backwash cleaning mechanism 728 to return the organisms 744 to source water 708. Smaller organisms 714 passing through filter stage 730 may face 100% mortality while passing through pump 732 or trapped in downstream filtration stages 734, 736, and 738, and the cleaning mechanism 728 may also cause significant mortality of organisms 744. Compared to inlet system 702, the disclosed multi-stage filtration system 700 allows for more efficient, safe, and effective return of captured and impacted solids to source water during the generation of filtered water.

[0076] According to the present invention, it should be understood that any number of filters, cleaning devices, valves, hydraulic ports, or pumps can be used as part of a filtration system. For example, in some cases, it may be desirable to include three or more filters with multiple (e.g., two or more) gap spaces to allow for further filtration of the source water. Furthermore, the filtration system may also include any number of electrical components, pump controllers, sensors, motors, software, or hardware for performing the filtration operation while safely displacing solids trapped in the source water. For example, one or more sensors may generate sensor signals indicating a triggering event. Triggering events may include the presence of a living organism, visual indications, time periods, flow rates, pressure drops, rotational speeds of one or more filters or cleaning devices, etc. Based on the sensor signals, the controller may sequentially switch the operating modes of one or more pumps or valves. Alternatively, in some examples, the pump controller may passively switch between operating modes. In one example, the pump may automatically switch between operating modes. Furthermore, each operating mode can occur with discrete cycle lengths. In one example, the first operating mode may have a longer cycle length than the second operating mode. However, alternatively, in other examples, the cycle lengths between the first and second cycles may be substantially equal.

[0077] The filtration system may also include one or more downstream desalination systems for reverse osmosis and freshwater production. For example, a first fluid path may include a passage through one or more filters of the feed water filter subsystem, the desalination system, and a freshwater outlet. Each respective filtration stage may be fluidly coupled. Alternatively, a second path may include a passage through one or more desalination systems, the feed water filter subsystem, and a source water outlet. In operation, the downstream desalination system may receive the filtered feed water stream from the feed water subsystem and produce freshwater. In this example, the filtration system may include any number of filtration stages to adequately filter the source water stream to a nominal particle size of approximately 5-10 micrometers, thereby minimizing clogging and fouling of the reverse osmosis membrane material and the crossflow space of standard spiral-wound elements.

[0078] It should also be understood that any or all pumps in a filtration system can be inline axial or mixed-flow pumps or similar high-capacity / low-pressure pumps that can move large volumes of fluid while overcoming relatively low pressure drops caused by upstream or downstream equipment, such as multi-stage filters or submerged reverse osmosis membrane elements. Axial / mixed-flow pumps may be advantageous because they produce minimal pressure changes, shear, turbulence, and other localized effects when operating at low speeds, which can kill or damage small entrained organisms by disrupting the osmotic balance of their cellular structures. However, other pump types (such as centrifugal or displacement pumps) that generate greater pressure differentials are acceptable when aquatic organism mortality is not a concern, such as when filtration is being carried out in dead zones where there is no apparent biological activity. Alternatively, pumps can also include life-friendly pumps that operate under parameters and conditions that do not pose a risk of death to the captured or trapped organisms.

[0079] Having thus described preferred embodiments of the invention, those skilled in the art will readily understand that the teachings herein can be applied to other embodiments within the scope of the appended claims. The full disclosure of all patents, patent documents, and publications is incorporated herein by reference as if individually incorporated.

Claims

1. A filtration system for generating filtered water and returning solids to the source water environment, comprising: At least one pump; An inlet filter subsystem fluidly coupled to the source water and the at least one pump is configured to receive the source water flow, capture organisms from the source water flow, and produce a filtered inlet water flow. and The system is configured to operate in multiple operating modes, wherein in a first operating mode, a filtered influent flow is received from the influent filter subsystem along a first fluid passage to generate filtered water at a first system outlet, and in a second operating mode, the filtered water flow is provided to a second fluid passage and a second system outlet to flush captured organisms back into the source water alive.

2. The filtration system of claim 1, wherein, The inlet filter subsystem is also configured to capture non-living solids from the received source water stream, and in the second operating mode, the filtered water stream flushes the captured non-living solids and organisms back into the source water.

3. The filtration system of claim 1 or 2, wherein, The first and second operating modes are configured to return at least 10% of the captured organisms alive to the source water.

4. The filtration system of claim 1 or 2, wherein, The first and second operating modes are configured to return at least 20% of the captured organisms alive to the source water.

5. The filtration system of claim 1 or 2, wherein, The first and second operating modes are configured to return at least 30% of the captured organisms alive to the source water.

6. The filtration system of claim 1 or 2, wherein, The first and second operating modes are configured to return at least 40% of the captured organisms alive to the source water.

7. The filtration system of claim 1 or 2, wherein, The first and second operating modes are configured to return at least 50% of the captured organisms alive to the source water.

8. The filtration system of claim 1 or 2, wherein, The first and second operating modes are configured to return at least 60% of the captured organisms alive to the source water.

9. The filtration system of claim 1 or 2, wherein, The first and second operating modes are configured to return at least 70% of the captured organisms alive to the source water.

10. The filtration system of claim 1 or 2, wherein, The first and second operating modes are configured to return at least 80% of the captured organisms alive to the source water.

11. The filtration system of claim 1 or 2, wherein, The first and second operating modes are configured to return at least 90% of the captured organisms alive to the source water.

12. The filtration system of any of the preceding claims, wherein, The inlet filter subsystem includes: Multiple filters separated by gap spaces, the gap spaces defining a fluid flow path between the downstream face of an upstream filter and the upstream face of a downstream filter. Furthermore, the second fluid passage includes the gap space and the flow that crosses the downstream filter face and the upstream filter face and leads to the outlet of the second system.

13. The filtration system of claim 12 wherein, Non-living solids and organisms are flushed back into the source water through the outlet of the second system, maintaining the source water environment near the filtration system.

14. The filtration system of claim 12, further comprising: A self-cleaning subsystem coupled to the inlet filter subsystem is configured to remove inactive solids and organisms from at least one of the plurality of filters and disperse the inactive solids and organisms within the interstitial space.

15. The filtration system of claim 14, wherein, The self-cleaning subsystem includes at least one of a brush, blade, piston, water sprayer, or air burster.

16. The filtration system of claim 12, wherein, The at least one pump includes a reversible pump configured to operate in a first operating mode to receive the source water flow and in a second operating mode to return the organism to the source water.

17. The filtration system of claim 12, wherein, In the second operating mode, the at least one pump generates back pressure to remove the organism from the source water or the interstitial space.

18. The filtration system according to claim 12, wherein, The inlet filter subsystem includes: At least three consecutive filters and at least two gap spaces, the gap spaces defining a fluid flow path across the downstream filter face and the upstream filter face leading to the outlet of the second system.

19. The filtration system of any of the preceding claims, wherein, The filtration system is configured to be submerged in the source water.

20. The filtration system of any of the preceding claims, wherein, The first operating mode includes a continuous flow of source water through the filtration system to generate a continuous flow of filtered water.

21. The filtration system of any of the preceding claims, wherein, The second operating mode is configured to occur intermittently based on detected triggering events.

22. The filtration system of claim 21, wherein, The detected triggering events include at least one of the following: the presence of an organism, visual indication, time period, flow rate, or pressure drop.

23. The filtration system of any of the preceding claims, wherein, The first fluid passage and the second fluid passage prevent captured non-living solids and organisms from entering the at least one pump.

24. The filtration system of any of the preceding claims, wherein, The first operating mode and the second operating mode each have a cycle length, and the cycle length of the first operating mode is longer than the cycle length of the second operating mode.

25. The filtration system according to any one of the preceding claims, wherein, The source water stream includes saline seawater.

26. The filtration system of claim 25, wherein, Also includes: At least one desalination system fluidly coupled to the inlet filter subsystem and the at least one pump, the at least one desalination system being configured to receive a salinized seawater flow and generate a desalinated water flow.

27. The filtration system of claim 26, wherein, The at least one desalination system includes: Multiple reverse osmosis membranes are configured to receive the salinized seawater flow and generate the desalinated water flow.

28. The filtration system of any one of claims 1 to 24, wherein, The source water includes fresh water, brackish water, or polluted water.

29. The filtration system of claim 28, wherein, The fresh water, the brackish water, or the polluted water is received from at least one of a river, reservoir, lake, or pond.

30. The filtration system of any of the preceding claims, wherein, The at least one pump is positioned downstream of all filtration stages to prevent organisms larger than the selected size from entering the at least one pump.

31. The filtration system of any of the preceding claims, wherein, The organisms include multicellular organisms.

32. The filtration system according to any one of the preceding claims, wherein, The organisms include single-celled organisms.

33. The filtration system according to any one of the preceding claims further comprises: At least one sensor is coupled to either or both of the first fluid passage and the second fluid passage and is configured to generate a sensor signal indicating the operating characteristics of the filtration system. and At least one controller is coupled to the at least one sensor and configured to receive sensor signals and modify the operating parameters of the filtration system based on the received sensor signals.

34. The filtration system of any of the preceding claims, wherein, The filtered water flow is supplied from the first outlet to the onshore cooling system.

35. The filtration system of any of the preceding claims, wherein, The filtered water is supplied from the first outlet to the marine cooling system.

36. The filtration system of claim 34 or 35, wherein, The onshore or offshore cooling systems include cooling systems used in power plants, data centers, or civil infrastructure.

37. The filtration system of any of the preceding claims, wherein, The filtered water stream is provided from the first outlet as process water for onshore or offshore operations.

38. The filtration system according to claim 37, wherein, The onshore or offshore operations include at least one of the following: water-intensive industrial operations, mining operations, oil and gas operations, semiconductor manufacturing operations, textile manufacturing operations, power generation operations, pharmaceutical manufacturing operations, marine carbon capture operations, seawater mineral harvesting operations, or pollution cleanup operations.

39. The filtration system of claim 1, wherein, The filtered water is supplied to irrigation, aquaculture, or fire-fighting industries.

40. A multi-stage filtration system for generating filtered water and returning captured solids to source water, comprising: At least one pump; An inlet filter subsystem, fluidly coupled to the at least one pump, is configured to receive a source water flow and filter organisms from the source water flow; A self-cleaning subsystem, coupled to the inlet filter subsystem, is configured to periodically remove organisms from the inlet filter subsystem and replace them in the gap space between the successive filters of the inlet filter subsystem. and The multi-stage filtration system is configured to operate in multiple operating modes. In a first operating mode, the inlet filter subsystem receives the source water flow along a first fluid path to generate filtered water flow. In a second operating mode, the filtered water flow is provided to the gap space, and the filtered water flow flows along a second fluid path across the downstream and upstream filter surfaces of the continuous filter and through the outlet of the multi-stage filtration system to return the organism to the source water.

41. The multi-stage filtration system of claim 40, wherein, The inlet filter subsystem is also configured to filter non-living solids from the received source water stream, and in the second operating mode, the filtered water stream returns the non-living solids and the organisms to the source water.

42. The filtration system according to claim 40 or 41, further comprising: A drive mechanism operatively coupled to the inlet filter subsystem and the self-cleaning subsystem to drive the inlet filter subsystem and the self-cleaning subsystem to move relative to each other.

43. The filtration system of claim 42, wherein, The drive mechanism drives the inlet filter subsystem to move when the self-cleaning subsystem remains stationary.

44. The filtration system of claim 42, wherein, The drive mechanism drives the self-cleaning subsystem to move when the inlet filter subsystem remains stationary.

45. The filtration system of claim 42, wherein, The drive mechanism drives the self-cleaning subsystem and the inlet filter subsystem to move.

46. ​​The filtration system according to any one of claims 40 to 45, further comprising: A valve subsystem fluidly coupled to the first fluid passage and the second fluid passage, and configured to control the source water flow and the filtered water flow through the first fluid passage and the second fluid passage.

47. A method for generating filtered water and returning captured solids to source water, the method comprising: In a first operating mode, a multi-stage filtration system is operated to receive a source water flow along a first fluid passage and generate a filtered water flow at a first system outlet, the first fluid passage including a plurality of continuously tapering filters configured to remove organisms from the source water flow. as well as The multi-stage filtration system is operated in a second operating mode to guide the filtered water flow along a second fluid passage to a second system outlet so that the organisms can return to source water. The second fluid passage includes a gap space between consecutive filters and a flow across the gap space of a downstream filter face and an upstream filter face leading to the second system outlet.

48. The method of claim 47, wherein, The source water flow also includes non-living solids.

49. The method according to claim 47 or 48, wherein, The multi-stage filtration system is configured to operate in the second operating mode after a triggering event, which includes the presence of a living organism, a visual indication, a time period, a flow rate, or a pressure drop.

50. The method of claim 49, wherein, The multi-stage filtration system is configured to passively switch between the first operating mode and the second operating mode.

51. The method of claim 49, wherein, The first and second operating modes are configured to return at least 50% of the captured organisms alive to the source water.

52. The method of claim 49, wherein, The first and second operating modes are configured to return at least 60% of the captured organisms alive to the source water.

53. The method of claim 49, wherein, The first and second operating modes are configured to return at least 70% of the captured organisms alive to the source water.

54. The method of claim 49, wherein, The first and second operating modes are configured to return at least 80% of the captured organisms alive to the source water.

55. The method according to claim 49, wherein, The first and second operating modes are configured to return at least 90% of the captured organisms alive to the source water.

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