CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims the benefit of pending U.S. Provisional Application No. 61/477,876, filed April 21 , 201 1 , which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The present technology relates generally to fluid filtration systems. In particular, several embodiments are directed toward gas introducer devices and associated systems and methods.

BACKGROUND

[0003] Purified water is used in many applications, including the chemical, power, medical and pharmaceutical industries, as well as for human consumption. Typically, prior to use, water is treated to reduce the level of contaminants to acceptable limits. Treatment techniques include physical processes such as filtration, sedimentation, and distillation; biological processes such as slow sand filters or activated sludge; chemical processes such as flocculation and chlorination; and the use of electromagnetic radiation such as ultraviolet light

[0004] Physical filtration systems are used to separate solids from fluids by interposing a medium (e.g., a mesh or screen) through which only the fluid can pass. Undesirable particles larger than the openings in the mesh or screen are retained while the fluid is purified. In water treatment applications, for example, contaminants from wastewater such as stormwater runoff, sediment, heavy metals, organic compounds, animal waste, and oil and grease must be sufficiently removed prior to reuse. Water purification plants and water purification systems often make use of numerous water filtration units for purification. It would be desirable to provide improved filtering units to reduce the expense and complexity of such purification systems.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 is a sectional view of a filtration apparatus in accordance with an embodiment of the present technology.

[0006] Figures 2 and 3 are enlarged views of a portion of the filtration apparatus of Figure 1 in accordance with embodiments of the present technology.

[0007] Figure 4 is a sectional view of a filtration apparatus in accordance with an embodiment of the present technology.

[0008] Figure 5 is a sectional view of a filtration apparatus in accordance with another embodiment of the present technology.

[0009] Figures 6-8 are sectional views of the filtration apparatus illustrated in Figure 5 in accordance with further embodiments of the present technology.

[0010] Figure 9 is a flowchart illustrating a method of filtering fluid in accordance with embodiments of the present technology.

DETAILED DESCRIPTION

[0011] The present technology is directed to fluid filtration systems having gas introducer devices and associated systems and methods. In several embodiments, for example, a filtration system includes a chamber having an inlet and an outlet. A filter belt is interposed between the inlet and the outlet. The filter belt is configured to trap contaminants while allowing fluid to pass from the inlet to the outlet. The filtering apparatus further includes a gas introducer configured to generate bubbles in the chamber proximate to the fluid inlet. In several embodiments, introduced gas bubbles can cause some types of contaminants, such as smaller or lighter contaminants, to rise upward and away from the filter belt. As such, the bubbles can be utilized to influence contaminant behavior in the contaminated water. For instance, the gas bubbles can lift relatively smaller contaminants away from the filter belt, causing a higher percentage of relatively large contaminants to initially contact the filter belt. These relatively large contaminants can form an accumulated porous solids layer on the belt. The gas bubbles can reduce an amount of small contaminants that pass through the filter belt during the initial stages of forming the accumulated porous solids layer. The accumulated porous solids layer can then serve to more finely filter subsequent contaminated fluid.

[0012] Figure 1 illustrates a filtration apparatus 100 having a filter belt 104 and a gas distribution mechanism 106 positioned in a filtering chamber 102. In this embodiment, the filter belt 104 is interposed between a fluid intake 108 and a fluid outlet 1 10. An inclined region 122 of the filter belt 104 is interposed between a first portion 124 of the chamber 102 and a second portion 126. The inclined region 122 can define an oblique angle a relative to a surface 130 of a contaminated fluid 132 in the first portion 124. (The specific oblique angle a is provided for purposes of explanation and is not intended to be limiting.) In further embodiments, the filter belt 104 can be horizontal or have other configurations. In various embodiments, the filter belt 104 can be rotated continuously or in an on-off manner as will be described in more detail below. A controller 1 18 can selectively the control the filter belt 104 and gas distribution mechanism 106.

[0013] The filter belt 104 can be porous such that fluid can pass through the filter belt 104 while at least some contaminants are too large to pass through the filter belt 104. These contaminants can build up on the filter belt's surface in an accumulated porous solids layer 148. The accumulated porous solids layer 148 can comprise a porous-solids gradient formed by particles ranging a particle size distribution. The accumulated porous solids layer 140 can provide augmented filtering capabilities compared to a clean filter belt 104. The accumulated porous solids layer 140 can comprise a temporary layer that can be removed from the filter belt 104.

[0014] The filter belt 104 can comprise a steel mesh, a coated mesh, a non-woven cloth belt, or other material. In some embodiments, the filter belt 104 comprises an endless or looped filter belt. As will be discussed in further detail below, the filter belt 104 can be rotated and the accumulated porous solids layer 148 removed from the filter belt 104 to allow continual operation. It is recognized here that rather than simply being a waste product, in some scenarios the accumulated porous solids layer 148 can significantly increase the filtering properties of the filter belt 104. For instance, in some scenarios, the accumulated porous solids layer 148 may offer filtration of contaminants that are an order of magnitude smaller than the contaminants blocked by a 'clean' filter belt 104. Thus, some of the present implementations can encourage the formation of the accumulated porous solids layer 148. The filtration apparatus 100 can also include an optional belt cleaning area 134 where contaminants are removed from the filter belt 104 as it is rotated by arrow 136.

[0015] In operation, fluid for treatment (e.g., contaminated water 132) can be received through the fluid intake 108 into the first portion 124 of the chamber 102. As mentioned above, the filter belt 104 can block or filter contaminants that have a diameter that exceeds a pore size of the filter belt 104. Initially, smaller contaminants can pass through the filter belt 104 with the filtered fluid 146. Stated another way, at start-up, the size of the contaminants blocked by the filter belt 104 generally depends on a pore size of the filter belt 104. For instance, if the pore size is 250 micrometers then contaminants that are about that size or larger are blocked by the filter belt while contaminants that are substantially smaller than 250 micrometers can pass through the filter belt. (A pore size of 250 micrometers is offered for purposes of explanation and is not intended to be limiting). During this initial phase, small contaminants that contact the filter belt 104 tend to pass through the filter belt and degrade the quality of the filtered fluid 146. Also during this initial phase, the blocked contaminants start to form the accumulated porous solids layer 148 on the inclined region 122, such as at a designated portion 150. In various embodiments, the filter belt 104 alone or with the accumulated porous solids layer 140 can be configured to block contaminants such as stormwater runoff, algae, sediment, heavy metals, organic compounds, animal waste, and/or oil and grease.

[0016] The gas distribution mechanism 106 can be positioned in the first portion 124 and produce bubbles 138 which influence the formation of the accumulated porous solids layer 148. More specifically, the contaminated fluid 132 can be exposed to the bubbles 138 in the first portion 124 and the bubbles 138 can serve to lift and in some cases float some of the contaminants in the contaminated fluid 132. The lifting action can cause the lifted contaminants to tend to remain in (or be lifted into) an upper horizontal zone 140 of the first portion 124 rather than sinking to a lower horizontal zone 142. In some cases, the lifting can carry the contaminants to the surface 130 of the contaminated fluid in the first portion 124.

[0017] In some embodiments, the bubbles 138 can be especially effective at lifting relatively small or light contaminants and contaminants that have a fat, oil, and/or grease (FOG) component. The bubbles can be less effective at lifting relatively large contaminants and/or heavy contaminants. Thus, viewed from one perspective, the gas distribution mechanism 106 can alter a contaminant profile of the fluid in the upper and lower horizontal zones. For instance, the gas distribution mechanism can increase concentrations of large contaminants and decrease concentrations of relatively small contaminants and/or FOG contaminants in the lower horizontal zone 142 and decrease the concentration of large contaminants and increase concentrations of relatively small contaminants and/or FOG contaminants in the upper horizontal zone 140. Though distinct upper and lower zones are designated in Figure 1 , the gas distribution mechanism 106 can be thought of as generally increasing large contaminants toward the bottom of the fluid column of the first portion 124 and generally increasing small contaminants and FOG contaminants toward the top of the fluid column of the first portion 124. The bubbles 138 can comprise various gases or combinations of gases in alternate embodiments. For example, the bubbles 138 can comprise air, nitrogen gas, nitrogen-enriched air, steam, or other gases.

[0018] In some implementations, the controller 1 18 can be manifest as a software, firmware, and/or hardware element of a computing device. A computing device can be any type of device that has some processing capability and some storage capability for storing computer-readable instructions. In some cases, the controller 1 18 can operate as an application on a personal computing device, or PC. The PC can communicate with other computing devices over a network, such as the Internet or a cellular network, among others. Of course, the computing device is not limited to a personal computing device and can be manifest as a smart phone, personal digital assistant, pad-type device, or other type of evolving or yet to be developed types of computing devices. In other cases, the controller 1 18 can be manifest as an application specific integrated circuit (ASICS), system on a chip, or in another manner.

[0019] Figures 2 and 3 are enlarged views of a portion of the filtration apparatus of Figure 1 in accordance with embodiments of the present technology. Figure 2 illustrates an enlarged view of the portion 150 of the filter belt 104 from the lower horizontal zone 142. In Figure 2, relatively large contaminants 204, relatively small contaminants 206, and FOG contaminants 208 are shown interfacing with filter belt pores 202. To avoid clutter on the drawing page, not all of the large contaminants 204, small contaminants 206, FOG contaminants 208 and pores 202 are designated with specificity. Further, the shapes of the relatively large contaminants 204, relatively small contaminants 206, and FOG contaminants 208 are illustrated in simplified form. Often the shapes and/or sizes will be more complex and/or varied than illustrated.

[0020] In the filter belt portion 150, the accumulated porous solids layer 148 is composed of a relatively high proportion of relatively large contaminants 204 and relatively small proportion of relatively small contaminants 206 and FOG contaminants 208. As mentioned above with reference to Figure 1 , bubbles from the gas distribution mechanism 106 tend to promote a high proportion of relatively large contaminants 204 in the lower horizontal zone 142. This proportion is reflected in the composition of the accumulated porous solids layer 148 in filter belt portion 150.

[0021] Viewed from one perspective, the filter belt portion 150 can be thought of as a base layer 210 of the accumulated porous solids layer 148. Due to the bubbles, the base layer 210 can be formed with relatively few small contaminants 206 passing through the filter belt 104 and degrading the filtered fluid 146. Alternatively or additionally, the base layer 210 can be formed with relatively few FOG contaminants 208 contacting the filter belt. This aspect will be discussed in more detail below. Briefly, FOG contaminants can be difficult to remove from the filter belt during the cleaning process. Reducing direct contact between FOG contaminants and the filter belt can ease cleaning and/or can result in a cleaner filter belt. Filtering of contaminated fluid 132 can continue to build the accumulated porous solids layer 148. Also, at this point, the accumulated porous solids layer 148 can contribute to the filtering process such that the presence of the accumulated porous solids layer 148 on the filter belt 104 provides more effective filtering than the filter belt 104 by itself.

[0022] Figure 3 shows an enlarged view of a filter belt portion 150' which can be thought of as a subsequent view of the portion 150 after the filter belt 104 has moved the portion 150 up the inclined region 122 while contaminated fluid 132 is filtered through the filter belt 104. Portion 150' includes the base layer 210 illustrated and described relative to FIG. 2. Further, portion 150' includes a second layer 302 of additional contaminants that have been blocked by, and added to, the accumulated porous solids layer 148. At least some of these additional contaminants are added in the upper horizontal zone 140 and thus include a higher concentration of smaller contaminants 206 and/or FOG contaminants 208. While the second layer 302 is shown largely above the first base layer 210, the second layer can also include small contaminants and/or FOG contaminants that are blocked within the base layer 210 by the relatively large contaminants 204 and thereby contribute to the structure of the accumulated porous solids layer 148. The combination of large contaminants 204 and small contaminants 206 can contribute to a complex accumulated porous solids layer 148 which can effectively filter contaminants that are much smaller than can be filtered by the filter belt 104 alone. In some cases, the complex accumulated porous solids layer 148 and the filter belt 104 can cooperatively filter contaminants that are an order of magnitude smaller than can be filtered by the filter belt 104 alone. For instance, continuing with the above example where the filter belt 104 has 250 micrometer pores 202, the addition of the complex accumulated porous solids layer 148 may allow filtering of contaminants in the 20-30 micrometer size or even smaller.

[0023] Returning to Figure 1 , recall that the bubbles 138 produced by the gas distribution mechanism 106 may lift small contaminants and/or FOG contaminants to the surface 130. These contaminants may contact the accumulated porous solids layer 148 at the intersection of the accumulated porous solids layer 148 and the surface 130 and be lifted from the contaminated fluid 132 by the accumulated porous solids layer 148 as the filter belt 104 is rotated. Lifting FOG contaminants with the accumulated porous solids layer 148 can make the filter belt 104 easier to clean at the belt cleaning area 134. In contrast, in cases where FOG contaminants contact the filter belt 104 directly, in addition to air which may be used to the clean the filter belt, large volumes of hot high pressure water may be consumed in the belt cleaning area 134 to dislodge the FOG contaminants. Large amounts of energy may be utilized to heat the water. The present implementations can produce a cleaner filter belt 104, reduce water and energy usage to clean the filter belt 104, and/or reduce an amount of wash water utilized to clean the filter belt 104. Accordingly, by creating an accumulated porous solids layer 148 that has relatively high concentrations of large contaminants against the filter belt 104 and relatively high concentrations of small contaminants and FOG contaminants in upper layers away from the filter belt 104, the cleaning process is greatly simplified. Further, the bubbles 138 tend to concentrate small contaminants and FOG contaminants in the upper horizontal zone 140. This can allow large contaminants to form a base layer of the accumulated porous solids layer 148 in the lower horizontal zone 142 with relatively few small contaminants passing through the filter belt 104 with the filtered fluid.

[0024] Figure 4 shows another filtration apparatus 100(1 ) in accordance with embodiments of the technology. For sake of brevity, the suffix (1 ) is used on elements that are generally similar to those discussed above relative to Figure 1 . The filtration apparatus 100(1 ) includes a chamber 102(1 ), a filter belt 104(1 ), and a gas distribution mechanism 106(1 ). The chamber 102(1 ) is configured with a fluid intake 108(1 ) and a fluid outlet 1 10(1 ). A controller 1 18(1 ) can selectively the control filter belt 104(1 ) and/or the gas distribution mechanism 106(1 ). For the sake of brevity, some elements that are substantially similar to the corresponding elements of FIG. 1 may not be re-introduced here.

[0025] An inclined region 122(1 ) of the filter belt 104(1 ) is interposed between a first portion 124(1 ) of the chamber 102(1 ) and a second portion 126(1 ). This configuration lacks the horizontal region of the filter belt illustrated in FIG. 1 . Other implementations may have still other filter belt layouts. Contaminated fluid 132(1 ) can be received from the intake 108(1 ) into the first portion 124(1 ). In this case, the contaminated fluid 132(1 ) enters into the first portion 124(1 ) proximate to a lower end of the inclined region 122(1 ) as indicated by an arrow 402 (e.g. the contaminated fluid 132(1 ) enters a lower horizontal zone 142(1 ) of the first portion 124(1 )). In contrast, in the implementation represented in Figure 1 , the contaminated fluid enters the first portion 124 vertically elevated (z-reference direction) from the lower end of the incline region (e.g. the contaminated fluid enters the upper horizontal zone 140(1 ) of the first portion 124(1 )). In the implementation shown in Figure 4, a baffle is used to direct the intake fluid to the lower horizontal zone. Other mechanisms can alternatively or additionally be employed.

[0026] In this embodiment, the controller 1 18(1 ) can selectively control one or more parameters associated with the gas distribution mechanism 106(1 ). For instance, the controller 1 18(1 ) can control a rate at which gas bubbles 138(1 ) are released by the gas distribution mechanism 106(1 ), a size of bubble released, a direction that the bubbles are released, and/or a position of the gas distribution mechanism in the filtration apparatus 100(1 ). For instance, the controller 1 18(1 ) can cause the gas distribution mechanism 106(1 ) to be moved in either or both of the vertical and horizontal directions (z and x- reference directions, respectively). For example, the gas distribution mechanism 106(1 ) can include a controllable drive mechanism, such as a motor that operates cooperatively with sets of belts and pulleys, gears and chains, hydraulic pistons, etc. The gas distribution mechanism 106(1 ) can entail an air stone, perforated pipe, air diffuser, air membrane, air dissolving tube, or other mechanism, that is positioned in the contaminated fluid and coupled to the controllable drive mechanism. The gas distribution mechanism 106(1 ) can be connected to a source of pressurized air, such as a compressor (not shown) which can be controlled by the controller 1 18(1 ).

[0027] The controller 1 18(1 ) can be communicatively coupled to the controllable drive mechanism to adjust the position of the gas distribution mechanism 106(1 ). In other implementations, the position of the gas distribution mechanism 106(1 ) can be adjusted by a user without the aid of the controller 1 18(1 ). In some cases, the user can access the controller 1 18(1 ) to adjust the position and/or other parameters associated with the gas distribution mechanism 106(1 ). Alternatively or additionally, the controller 1 18(1 ) may adjust parameters associated with the gas distribution mechanism 106(1 ) based upon one or more conditions, such as input from sensors associated with the filtration apparatus 100(1 ). Examples of sensors are discussed below relative to Figures 5-8. [0028] As mentioned above, the position of the gas distribution mechanism 106(1 ) can be adjusted based upon various conditions. For instance, at startup (i.e., before the accumulated porous solids layer 148(1 ) has been formed on the inclined region 122(1 ) of the filter belt 104(1 )) the gas distribution mechanism 106(1 ) may be moved downward. In this downward position, bubbles from the gas distribution mechanism can serve to carry all but the largest contaminants upward and away from the filter belt. The remaining large contaminants can travel with the contaminated fluid 132(1 ) toward the filter belt. These large contaminants can begin to form the accumulated porous solids layer 148(1 ) when blocked by the filter belt 104(1 ). Subsequently, the gas distribution mechanism 106(1 ) may be adjusted vertically upward to promote the upward movement of very small contaminants and/or FOG contaminants which may be more effectively filtered in the upper horizontal zone 140(1 ) and/or at the surface 130(1 ). In another case, the gas distribution mechanism 106(1 ) may be turned off once a base layer of large contaminants has been formed on the filter belt 104(1 ). (Examples of base layers are described above with reference to Figures 2-3.) The gas distribution mechanism 106(1 ) may be turned back on when the filter belt 104(1 ) is rotated so that the bubbles 138(1 ) can once again aid in the formation of the base layer on the newly exposed filter belt 104(1 ). As described above, the bubbles 138(1 ) can aid in the formation of the base layer in a way that can reduce small contaminants passing through the filter belt 104(1 ) into the filtered fluid 146(1 ) and/or reduce direct contact between FOG contaminants and the filter belt 104(1 ).

[0029] Figure 5 is a sectional view of a filtration apparatus 100(2) in accordance with embodiments of the present technology. For sake of brevity the suffix (2) is used on elements that are similar to those discussed above relative to FIG. 1 to avoid redundant description. For purposes of explanation, Figure 5 illustrates the filtration apparatus 100(2) at an initial time, such as start-up of the filtration apparatus 100(2). Figures 6-8 are sectional views of the filtration apparatus 100(2) at subsequent sequential times.

[0030] Referring to Figures 5-8 collectively, the filtration apparatus 100(2) includes a filtered fluid diversion structure 502. The fluid diversion structure 502 can function to separate filtered fluid which passes through an upper section 504 of an inclined region 122(2) from filtered fluid that passes through a lower section 506 of the inclined region. In this embodiment, the inclined region 122(2) is exposed to the contaminated fluid 132(2) along a length L. The fluid diversion structure 502 approximately bisects the length L such that the upper section 504 and the lower section 506 each comprise approximately one- half of the length L.

[0031] The filtration apparatus 100(2) also includes two fluid outlets 508 and 510 and three controllable valves 512, 514, and 516 that are communicatively coupled to a controller 1 18(2). The filtration apparatus 100(2) can also include multiple gas distribution mechanisms. The illustrated embodiment includes three gas distribution mechanisms 520, 522, and 524. Other implementations can utilize one, two, or four or more gas distribution mechanisms. In the illustrated embodiment, the three gas distribution mechanisms 520, 522, and 524 are positioned in spaced relation to one another in a boundary between an upper horizontal zone 140(2) and a lower horizontal zone 142(2). Other implementations can employ other positioning configurations. The illustrated embodiment further includes four fluid quality sensors 526, 528, 530, and 532 and three fluid flow sensors 534, 536, and 538. Further embodiments can include more or fewer sensors which sense fluid flow, quality, pressure, or other characteristics.

[0032] Turning more specifically now to Figure 5, contaminated fluid enters a first portion 124(2) from an intake 108(2). At this point, a filter belt 104(2) is "clean" (e.g., no accumulated porous solids layer on the incline region 122(2) beneath a fluid surface 130(2)). The controller 1 18(2) can cause all three gas distribution mechanisms 520, 522, and 524 to produce gas bubbles 138(2). These gas bubbles tend to maintain relatively small contaminants and/or FOG contaminants in an upper horizontal zone 140(2) while allowing larger contaminants to travel downward and encounter the filter belt 104(2) in a lower horizontal zone 142(2). This phenomenon may be especially pronounced in the lower section 506 which can include a relatively high percentage of large contaminants and a relatively low percentage of small contaminants and/or FOG contaminants. At this point, as indicated at positions 540 and 542, contaminated fluid 132(2) can pass through the inclined region 122(2) of the filter belt and become filtered fluid 146(2). Due to the absence of an accumulated porous solids layer, the filtered fluid 146(2) may or may not have a contaminant profile that satisfies effluent specifications. Out of an abundance of caution, the controller 1 18(2) can cause the filtered fluid to be recycled for further processing. Specifically, the controller 1 18(2) can open the controllable valves 512 and 514 and close the controllable valve 516. Thus, with the aid of a pump 544, the filtered fluid 146(2) can be returned to the intake 108(2) for further processing.

[0033] Figure 6 shows the filtration apparatus 100(2) at a subsequent point of operation. At this point, a base layer of an accumulated porous solids layer 148(2) is formed along length L of the inclined region 122(2). The controller 1 18(2) can turn off one or more of the gas distribution mechanisms 520, 522, and/or 524. In this example, the controller 1 18(2) turns off the gas distribution mechanisms 520 and 524 and continues to cause gas bubbles to be produced by the gas distribution mechanism 522 to lift FOG and/or small contaminants toward surface 130(2). In this case, the base layer of the accumulated porous solids layer 148(2) can block other contaminants which then further contribute to the accumulated porous solids layer 148(2). Recall that as a thickness and/or complexity of the accumulated porous solids layer builds, the accumulated porous solids layer itself begins to filter smaller contaminants that would otherwise likely pass through the filter belt 104(2). Due to the effective accumulated porous solids layer 148(2), the profile of the filtered fluid 146(2) may satisfy the desired specifications. As such, the controller 1 18(2) can close the controllable valve 512 and open the controllable valves 514 and 516. In this configuration, the filtered fluid can flow from the outlet 510 as effluent. The filtration apparatus 100(2) can operate in this condition until the thickness and/or complexity of the accumulated porous solids layer 148(2) slows a fluid filtration rate (e.g., the amount of fluid passing through the incline region 122(2) of the filter belt per unit of time) below a predefined value.

[0034] Figure 7 shows a subsequent view of the filtration apparatus 100(2). In this illustration, the controller 1 18(2) has caused the filter belt 104(2) to rotate approximately one-half of length L. Essentially, the accumulated porous solids layer 148(2) that was on the upper section 504 is out of the first portion 124(2) and is approaching a belt cleaning area 134(2). Accordingly, upon rotation of the filter belt, some or all of the inclined region 122(2) can be filtering contaminated fluid without the aid of a accumulated porous solids layer 148(2). The lower section 506 now comprises newly exposed filter belt (e.g., without the accumulated porous solids layer 148(2).

[0035] The controller 1 18(2) may utilize various conditions to determine when to rotate the filter belt 104(2). In one example introduced above, the controller 1 18(2) may rotate the filter belt 104(2) when fluid flow through the filter belt 104(2) drops below a predefined value. In another case, the controller 1 18(2) may cause the filter belt 104(2) to rotate after a predefined period of operation.

[0036] At approximately the same time as rotating the filter belt 104(2), the controller 1 18(2) can also control other filtration apparatus structures and/or functions. For instance, in this example, the controller 1 18(2) can close the control valve 514, and open the control valve 512. In this example, the control valve 514 is the only path through the fluid diversion structure 502. Accordingly, closing the control valve 514 can effectively separate fluid that is filtered through the upper section 504 from fluid that is filtered through the lower section 506. Thus, filtered fluid 146(2) that passes through the upper section 504 of the filter belt 104(2) that has the accumulated porous solids layer 148(2) can be treated as effluent at the outlet 510. In contrast, filtered fluid 146(2) that passes through the lower section 506 that does not have the accumulated porous solids layer 148(2) can be recycled via the outlet 508.

[0037] Further, to aid in formation of the accumulated porous solids layer 148(2) and to reduce the amount of small contaminants that pass through the lower section, the controller 1 18(2) can cause the gas distribution mechanisms 520 and 524 to start producing bubbles 138(2) again. The bubbles 138(2) from the gas distribution mechanisms 520-524 can reduce the concentration of small contaminants in the lower section 506 during formation of a new accumulated porous solids layer base layer on this section. The bubbles 138(2) can decrease small contaminant and/or FOG contaminant concentrations in the lower horizontal zone 142(2) (and thereby the lower section) by carrying these contaminants upward in the upper horizontal zone 140(2).

[0038] Figure 8 shows a still subsequent view of the filtration apparatus 100(2). At this point, a base layer 802 of the accumulated porous solids layer 148(2) has formed on the lower section 506. The base layer 802 can be similar to the base layer 210 described above relative to Figures 2-3. Specifically, the base layer can be formed predominantly from relatively large contaminants that are approximately equal to or larger than a pore size of the filter belt 104(2). At this point, the controller 1 18(2) also turns off the gas distribution mechanism 524. Turning off this gas distribution mechanism 524 can allow a modest increase in the percentage of small contaminants and/or FOG contaminants reaching the lower horizontal zone 142(2). These small contaminants and/or FOG contaminants can contribute to further formation of the accumulated porous solids layer 148(2) as explained above with reference to Figures 2-3. At some point, the accumulated porous solids layer 148(2) on the lower section 506 can mature to a point that fluid filtration through the lower section can satisfy a desired profile. At that point, the controller 1 18(2) can reconfigure the filtration apparatus 100(2) to the configuration illustrated in Figure 6. The configurations shown in Figures 6-8 can then be repeated in an iterative manner.

[0039] In some implementations, the controller 1 18(2) can control the rotation of the filter belt 104(2) and/or the gas distribution mechanisms 520-524 based at least in part on input from one or more of sensors 526-538. One such implementation will be explained relative to FIGS. 5-8.

[0040] Referring back to Figure 5, the controller 1 18(2) can recognize system start-up when the controllerl 18(2) starts to receive values from the fluid flow sensor 534 (e.g., contaminated fluid 132(2) begins flowing through the inlet 108(2) into the chamber 102(2)). The controller 1 18(2) can also receive fluid quality values for the incoming contaminated fluid from fluid quality sensor 526. As fluid flows through the filter belt 104(2), the controller 1 18(2) can receive fluid quality values from fluid quality sensors 528 and 530. The controller 1 18(2) can determine from these fluid quality values whether effective filtering is occurring at either or both of the upper and/or lower sections 504 and 506. The controller 1 18(2) can be set to a default condition that recycles the filtered fluid 146(2) until the controller 1 18(2) determines that the filtered fluid through one or both of the upper and lower sections 504, 506 satisfies a desired fluid contaminant profile. For instance, the controller 1 18(2) may by default close the control valve 516 and open the control valves 512 and 514 so that the filtered fluid 146(2) is recycled to the intake 108(2). At system startup, the controller 1 18(2) can also activate the gas distribution mechanisms 520-524. Gas bubbles 138(2) from the gas distribution mechanisms 520-524 can reduce relative concentrations of small contaminants and/or FOG contaminants proximate the filter belt 104(2). Thus, relatively large contaminants can form a base layer on the filter belt as described above. At a subsequent point, these large contaminants can contribute to the initial formation. Over time, the evolving accumulated porous solids layer 148(2) can contribute to fluid filtration and thereby improve fluid quality as measured by the fluid quality sensors 528 and 530 that sense filtered fluid 146(2). The controller 1 18(2) can use the information from the fluid quality sensors 528, 530 in controlling the filter belt 104(2) and the control valves 512-516.

[0041] Referring now to Figure 6, the controller 1 18(2) determines from the values received from fluid quality sensors 528 and 530 that the filtered fluid 146(2) has improved to the point that the filtered fluid satisfies the fluid quality profile. Accordingly, the controller 1 18(2) the closed controllable valve 512 and opened controllable valves 514 and 516 so that the filtered fluid reaches outlet 510. Further, the controller 1 18(2) has deactivated the gas distribution mechanisms 520 and 524 so that more of the small contaminants and FOG contaminants can be captured by and contribute to the accumulated porous solids layer 148(2). The controller 1 18(2) can leave some of the gas delivery mechanisms running. Even in the presence of an effective accumulated porous solids layer 148(2), gas bubbles from the gas delivery mechanism(s) can help to form a 'scum layer' on the surface 130(2). The scum layer can include gas bubbles, FOG contaminants, and/or small contaminants, among others.

[0042] The controller 1 18(2) can then receive fluid flow values from the fluid flow sensor 538. At some point, the accumulated porous solids layer 148(2) may become so thick and/or dense that the flow of fluid through the accumulated porous solids layer 148(2) as captured by the fluid flow values falls below a predefined level. Responsively, the controller 1 18(2) can rotate the filter belt 104(2) to expose clean filter belt 104(2) on the lower section 506 as illustrated in Figure 7. In other implementations, decreased fluid flow through the accumulated porous solids layer 148(2) can be indirectly sensed by sensing the fluid level. A rising fluid level in the first portion 124 (e.g., rising surface 130) can indicate decreasing fluid flow. Thus, this fluid level can be utilized as a parameter for determining when to rotate the filter belt 104(2).

[0043] Rotating the filter belt 104(2) can lift the scum layer off of surface 130(2) where the surface contacts the filter belt. Lifting off the scum layer can be a very effective way of removing contaminants from the contaminated fluid 132(2). When rotating the filter belt 104(2), the controller 1 18(2) can open the controllable valve 512 and close the controllable valve 514. Thus, the fluid diversion structure 502 physically separates filtered fluid 146(2) that passes through the upper section 504 from filtered fluid that passes through the lower section 506. The filtered fluid that passes through the upper section 504 can be treated as effluent at the outlet 510. The filtered fluid that passes through the lower section 506 can be recycled to the inlet 108(2) while the accumulated porous solids layer 148(2) begins to form. The controller 1 18(2) can decrease the incidence of small particles passing through the filter belt 104(2) and/or facilitate formation of the accumulated porous solids layer 148(2) by activating the gas distribution mechanisms 520-524 to reduce concentrations of small contaminants and/or FOG contaminants in the lower horizontal zone 142(2). During this time, the controller 1 18(2) can evaluate values from the fluid quality sensor 530. When the values indicate that the contaminant profile of the filtered fluid 146(2) from the lower section is acceptable, the controller 1 18(2) can close the control valve 512 and open the control valve 514 as illustrated in Figure 6. The controller 1 18(2) can then allow the filtration apparatus 100(2) to run until the values from the fluid flow sensor 538 indicate that the accumulated porous solids layer 148(2) is inhibiting fluid flow below an acceptable level. The controller 1 18(2) can then rotate the filter belt as illustrated and discussed relative to Figure 7.

[0044] Figure 9 is a flowchart illustrating a method 900 of filtering fluid in accordance with embodiments of the present technology. The method 900 may be implemented in connection with a filtration system such as those described above with reference to Figures 1 -8. The method includes rotating a filter belt operating in contaminated fluid to expose a new section of the filter belt to contaminated fluid (block 902). The method 900 further includes causing gas bubbles to be introduced into the contaminated fluid in a manner that reduces concentrations of relatively small contaminants of the contaminated fluid proximate to the new section (block 904). The order in which the above method 900 is described is not intended to be construed as a limitation, and any number of the described blocks can be combined in any order to implement the method 900, or an alternate method. Furthermore, the method 900 can be implemented in any suitable hardware, software, firmware, or combination thereof such that a computing device can implement the method 900. In one case, the method 900 is stored on a computer- readable storage media, such as RAM, hard drive, optical disc, etc., as a set of instructions such that execution by a computing device, causes the computing device to perform the method 900.

[0045] PCT Application No. US12/34573, filed April 20, 2012, is incorporated herein by reference in its entirety. From the foregoing, it will be appreciated that specific embodiments of the technology have been described herein for purposes of illustration, but that various modifications may be made without deviating from the disclosure. For example, while various attributes of the fluid flow or the filtering apparatus 100 are designated as "upper", "lower", "left", "right", "upwardly-facing", "downward", etc., these terms are used only for purposes of explaining of the accompanying drawings. For example, in some embodiments, an inlet may be at a lower height than an outlet and/or fluids may be filtered upwards through a filter mesh such that gravity assists in keeping contaminants from piercing an overhead filter. In still further embodiments, the filtration systems may include additional features, such as overflow chambers, fluid routing systems, or additional flow paths. Additionally, while advantages associated with certain embodiments of the new technology have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the technology. Accordingly, the disclosure and associated technology can encompass other embodiments not expressly shown or described herein. Thus, the disclosure is not limited except as by the appended claims.