Scalable floating micro-aeration unit, device and method

Abstract

Disclosed are floating micro aeration unit (FMU) devices, systems and methods for biologically removing sulfide from water / wastewater bodies and streams. In some aspects, the system includes: a manifold structure including one or more openings to allow air to flow out from the interior of the manifold structure; one or more support structures connected to the manifold structure, wherein the one or more support structures are buoyant on the surface of a fluid including water or wastewater; and an air source that flows air to the manifold structure, so that the manifold structure supplies air containing a predetermined amount of oxygen (e.g., less than 0.1 mg / L of oxygen) to oxidize sulfide in the fluid.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent document claims priority to and the benefit of U.S. Provisional Patent Application No. 62 / 811,496, entitled “SCALABLE FLOATING MICRO-AERATION UNIT, DEVICES AND METHODS,” filed on February 27, 2019. The entire contents of the above patent application are incorporated by reference as part of the disclosure of this patent document. Technical Field

[0003] This patent document relates to water and wastewater technology. Background Art

[0004] For safety and environmental protection purposes, strict limits have been set by law in many industrialized countries on the permissible emissions of sulfur and its compounds, particularly hydrogen sulfide, into the atmosphere. As such, there is a growing interest in the development of efficient and low-cost methods for removing sulfur from contaminated water while minimizing the emission and release of sulfur and its compounds. Summary of the invention

[0005] Disclosed are scalable micro-aeration devices, systems and methods for removing sulfide (sulfide ions) from water and wastewater bodies and streams.

[0006] In some aspects, a system for removing sulfide from water or wastewater includes: a manifold structure including one or more openings to allow air to flow out from the interior of the manifold structure; one or more support structures connected to the manifold structure, wherein the one or more support structures are floatable on the surface of a fluid including water or wastewater; and an air source configured to provide air to the manifold structure so that the air flows out of the manifold structure through the one or more openings located at the fluid to promote oxidation of sulfide in the fluid, wherein the air flowing out from the interior of the manifold structure includes oxygen in an amount containing less than 0.1 mg / L oxygen (O2).

[0007] In some aspects, a method of removing sulfide from a fluid containing water or wastewater includes: contacting the fluid containing water or wastewater with a manifold structure, the manifold structure including one or more openings to allow air to flow out from the interior of the manifold structure, wherein the manifold structure is configured to float on the surface of the fluid based on one or more support structures connected to the manifold structure; allowing air to flow out from the interior of the manifold structure to supply oxygen gas containing less than 0.1 mg / L oxygen (O2) to the fluid; and converting sulfide from the fluid into elemental sulfur (elemental sulfur).

[0008] The subject matter described in this patent document can be implemented in specific ways that provide one or more of the following features. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1A and 1B A diagram showing an example embodiment of a floating micro aeration unit (FMU) in accordance with the present technology for removing sulfide from water and / or wastewater bodies and streams.

[0010] Figure 1C An image of biofilm growth on an example implementation of an FMU device is shown.

[0011] Figure 1D and 1E A diagram showing an example implementation of a FMU in accordance with the present technology for removing sulfide from water and / or wastewater bodies and streams.

[0012] Figure 2A and 2B Images of an FMU device from an example implementation with and without sulfide oxidizing bacteria growth material are shown, respectively.

[0013] Figure 2C An image of an aeration ring and aeration modules showing an example implementation of an FMU apparatus.

[0014] Figure 3A and 3B Shown are data plots depicting a flow simulation of air flow and air distribution at the water and / or wastewater surface of an example FMU device.

[0015] Figure 4 An image showing an example implementation of a FMU device according to some embodiments of the present technology connected to an example microbial fuel cell (MFC) reactor to form a FMU-MFC system.

[0016] Figure 5 Shown are data plots depicting the cathode potential of an MFC reactor of an example embodiment with and without an FMU device.

[0017] Figure 6 A schematic diagram of an example implementation of a FMU-MFC system in an example implementation for brewery wastewater treatment is shown.

[0018] Figure 7 The diagram depicts the process used to treat brewery wastewater. Figure 6Figure 1 shows a plot of sulfate and sulfide concentrations over time for an example FMU-MFC system.

[0019] Fig. 8A and 8B Shown is a data plot depicting sulfate (sulfate) and sulfide (sulfide ion) concentrations over time for an example FMU-MFC system in an example implementation for treating food processing wastewater. DETAILED DESCRIPTION

[0020] In water and wastewater treatment and odor management, high sulfide concentrations are a major problem. Water and wastewater rich in sulfate and sulfide can cause rapid corrosion of metals and concrete, emit unpleasant odors, and are toxic to humans. The presence of sulfide in wastewater causes corrosion of water delivery systems and accumulation of metal sulfides in biosludge. In addition, sulfide is toxic for methanogens and causes inhibition of anaerobic water treatment processes in most cases. Therefore, the presence of sulfide dissolved in water / wastewater has become a significant problem in anaerobic digestion as a wastewater treatment process.

[0021] Under anaerobic conditions, sulfate-reducing bacteria use sulfate as the final electron acceptor for the degradation of organic matter present in water. Thus, sulfate is reduced to hydrogen sulfide and subsequently distributed in both the liquid and gas phases (e.g., as biogas). The reduction of sulfate is undesirable and can be a parasitic reaction in wastewater treatment, leading to the production and accumulation of hydrogen sulfide.

[0022] One way to treat sulfide in water is to use micro-aeration. A micro-aeration unit is a device that supplies a small amount of air on the surface of the water, which is used by sulfur-oxidizing bacteria to convert sulfide dissolved in the water into elemental sulfur and thereby remove sulfide from the water body. Typically, micro-aeration allows a small ("micro") amount of oxygen (e.g. <0.1 mg / L O2) to be supplied to the gas phase, as in the following example reaction.

[0023] 2HS - +O2→2S o +2OH - (Under microaerobic conditions) (Equation 1)

[0024] Under microaerobic conditions, the sulfide-oxidizing bacteria present convert sulfide into elemental sulfur, which is removed from the gas phase and no longer an impurity in the biogas.

[0025] At higher oxygen concentrations (e.g., >0.1 mg / L O2), sulfide is oxidized back to sulfate or thiosulfate. Therefore, oxygen concentration is critical for sulfide removal, and higher oxygen concentrations are undesirable.

[0026] 2HS - +2O2→S2O3 2- +2H2O (at higher oxygen levels) (Equation 2)

[0027] 2HS - +4O2→2SO4 2- +2H + (In excess oxygen) (Equation 3)

[0028] Conventional micro-aeration devices have been developed and used for sulfide removal in the gas phase, but conventional micro-aeration devices have not been designed and explored for sulfide removal in water and wastewater bodies. For example, in contrast to preventing the introduction of sulfide in the gas phase in the first place, conventional micro-aeration units are used for post-treatment of anaerobically digested methane generated by anaerobic digestion systems. In addition, conventional micro-aeration devices have a fixed structure, which limits the amount of water that can be purified to a desired purification level or range. Further, since the design of conventional micro-aeration devices focuses on the removal of sulfide in the gas phase (e.g., post-treatment), they do not provide uniform micro-air distribution. In addition, conventional micro-aeration devices tend to be small devices, requiring purified gas or methane to pass through these devices, and as such, the small size of these devices limits their applicability on a larger scale. As such, there is a need for new methods that can overcome these and other deficiencies of existing micro-aeration technologies.

[0029] Disclosed are scalable micro-aeration devices, systems and methods including floating micro-aeration units (FMUs) for removing sulfide from water and wastewater bodies or streams. For example, in various implementations, the floating characteristics of the disclosed micro-aeration techniques and devices allow and control the air supply only at the water surface without aerating the main water body and thereby interfering with the anaerobic treatment process. Some embodiments of the disclosed FMU devices, systems and methods described herein use sulfur-oxidizing bacteria that can convert sulfide dissolved in water into elemental sulfur in the presence of micro-oxygen concentrations.

[0030] In some implementations, the FMU according to the present technology is designed to provide microaerobic conditions at the water-air interface. By creating microaerobic conditions at the water-air interface, the device can aerate the top layer of the water surface so that the remaining part (e.g., the main part) of the water body is maintained under anaerobic conditions. This is important for anaerobic wastewater treatment technologies such as anaerobic digestion and MFCs. For example, aeration of the entire water body will introduce significant changes in the microbial population in the reactor, and the treatment process is converted from an anaerobic process to an aerobic process. This situation occurs, for example, because the higher oxygen concentration in the anaerobic digester will produce a toxic effect on methanogenesis and methane generation.

[0031] For example, in some applications, the FMU devices, systems and methods may be used to remove sulfides from methane because hydrogen sulfide can corrode materials, such as those used in cogeneration systems that convert methane into electricity.

[0032] In some implementations, example embodiments of FMUs according to the present technology are designed to remove hydrogen sulfide from the liquid phase. For example, since most sulfide removal occurs at the gas-liquid interface, the FMU supplies low oxygen concentrations at the gas-liquid interface, where sulfide oxidizing bacteria are intentionally grown. In contrast to being permanently fixed, the micro-aeration device is free-floating, which allows for effective treatment of variable water and / or wastewater volumes. The floating micro-aeration method can be implemented directly in existing water bodies, or can be explored as a separate flow-through unit.

[0033] The implementation of the disclosed embodiment of the FMU can include one or more of the following features and advantages. For example, the various embodiments of the disclosed FMU device have a scalable design and structure (architecture), which allows the FMU device to determine the size based on the characteristics (details) of the wastewater treatment facility. For example, the FMU can be designed as an independent unit through which water and / or wastewater flows, or the FMU can be combined in an existing water and / or wastewater treatment unit (such as a storage tank or a balancing tank). The size of the FMU depends on the volume and flow rate of the water and / or wastewater. The independent FMU is "plug-and-play" and does not require any infrastructure changes. This also applies to, for example, a FMU embedded in an existing tank.

[0034] In addition, for example, the disclosed FMU systems, methods, and apparatus can be employed for any wastewater treatment at different scales. Although some example implementations described herein are primarily based on treating brewery wastewater using certain example embodiments of the FMU systems and methods to facilitate understanding of the underlying concepts, such as brewery wastewater, it is understood that the disclosed embodiments may also include treatment of other wastewaters other than brewery sources.

[0035] Brewery wastewater is characterized by high protein and sulfate content. Therefore, brewery wastewater releases significant amounts of sulfide during its degradation. The low chemical oxygen demand (COD) to sulfide ratio (COD / S) of 3 / 50 in brewery wastewater also leads to the production of large amounts of hydrogen sulfide.

[0036] Table 1 contains examples of the chemical composition of brewery wastewater.

[0037] Table 1

[0038] parameter concentration Total Chemical Oxygen Demand (COD(T)) 2960mg / L Soluble Chemical Oxygen Demand (COD(S)) 2320mg / L Volatile fatty acids 556mg / L protein 161mg / L pH 7.57 Conductivity 5.78mS / cm Sulfide 0.13mg / L Sulfate (sulfate ion, sulfate ester) 110mg / L Nitrate (nitrate ion, nitrate ester) 26mg / L Nitrite (nitrite, nitrite ester) 0mg / L Phosphate (phosphate, phosphate ester) 610mg / L Total suspended solids 1933mg / L Total inorganic nitrogen 38mg / L

[0039] Figures 1A-1C A diagram showing an example embodiment of an FMU device 100 according to the present technology for removing sulfide from different types of wastewater, including waste from national infrastructure systems, agriculture, and industrial systems. In some embodiments, the FMU device 100 is a stand-alone unit. In other embodiments, the FMU device 100 can be incorporated into existing water and wastewater treatment units. Figures 1A-1C In the exemplary embodiment of the FMU device 100 depicted in FIG. 1 , the FMU device 100 is a stand-alone unit.

[0040] refer to Figure 1A , the FMU device 100 includes or is combined with a wastewater storage tank 101 to receive raw wastewater for treatment, for example, from a facility such as a brewery, a farm, or a municipal waste water network. Connected to the wastewater storage tank 101 is an inflow line 102 in which wastewater water flows from a wastewater reservoir to the wastewater storage tank 101 for subsequent treatment. The wastewater storage tank 101 is further connected to an outflow line 103, which allows the wastewater to leave the wastewater storage tank 101 once it has been treated. In various implementations, the inflow line 102 and the outflow line 103 can be located at any position on the wastewater storage tank 101 so that they allow wastewater to flow into and out of the wastewater storage tank 101.

[0041] As in Figures 1A-1C As shown in the example embodiment shown in FIG. 1 , the FMU device 100 includes an aeration module 105 (also referred to as an aeration manifold). The aeration module 105 includes a manifold structure having one or more openings for allowing air to flow out from the interior of the manifold structure. For example, the manifold structure can be configured as a ring, a polygon (e.g., a triangle, rectangle, pentagon, hexagon, or octagon or other polygon), or other shapes or geometric structures. Figure 1A and 1BIn the example of , the aeration module 105 is configured as an aeration ring 105A. The aeration ring 105A floats on the top of the wastewater contained in the wastewater storage tank 101. In the case of using a floating support 104, the aeration ring 105A can float on the top of the wastewater storage tank 101, and the floating support 104 includes one or more support structures that can float on the aqueous fluid solution. In some embodiments, the aeration ring 105A places the floating support 104 between the wastewater and the aeration ring 105A, so that the aeration ring 105A will float on the top of the wastewater in the storage tank 101. In such an embodiment, the floating support 104 can be configured to prevent the aeration ring 105A from directly contacting the wastewater fluid in the wastewater storage tank 101. And in some embodiments, the floating support 104 can be configured to allow the aeration ring 105A to contact the wastewater. For example, in some embodiments, the floating support 104 can position the aeration ring 105A in the wastewater so that the aeration ring 105A is at least partially submerged (e.g., halfway into the water); wherein the degree to which the aeration ring 105A is submerged in the wastewater can depend on the weight of the aeration ring 105A and the buoyancy properties of the floating support 104. In particular, in any configuration that places the aeration ring 105A in contact with the water, the placement of the aeration ring 105A provides a small amount of air at the water-air surface of the wastewater. In various implementations, the floating support 104 can maintain the FMU device 100 on the surface of the water regardless of the volume of water and / or wastewater in the wastewater storage tank 101. This feature allows the volumetric load of wastewater in the wastewater storage tank 101 to be variable and ensures a predetermined distance between the wastewater surface and the aeration ring 105A.

[0042] In some embodiments, the FMU device 100 includes a cover 106, which provides a volume (e.g., "head space") that allows uniform air distribution on the surface of water and / or wastewater between the aeration ring 105A and the cover 106. In some embodiments, the cover 106 can move up and down relative to the side wall of the container to increase or decrease the volume of the "head space". In some embodiments including the cover 106, the FMU device 110 includes a hole 110 on the top of the cover 106, which allows air to be released so that air flows into and out of the head space, such as providing ventilation and preventing pressure accumulation. The FMU 100 includes an air line 107 to provide air to the aeration ring 105A under controlled parameters. The precise control of the incoming air flow allows accurate micro-dosing of oxygen at the surface of the water. Micro-oxygen concentration is critical for ensuring the correct biological conversion of sulfide to elemental sulfur, which is opposite to the conversion of sulfide to sulfate or thiosulfate. The concentration of oxygen may be adjusted (eg, controlled) by flow control.

[0043] In some embodiments, the aeration ring 105A may have two, three, four or more air lines 107. The air lines 107 allow air to flow to the aeration ring 105A and oxygenate the wastewater at the top surface and / or surface layer of the wastewater storage tank 101. In some implementations, the surface layer of the wastewater refers to a depth of about 0 cm to about 5 cm from the top surface of the wastewater surface. For example, the FMU device 100 can promote oxidation of sulfides at the surface layer of the wastewater and / or on the top layer of the wastewater (e.g., 0 cm to about 5 cm from the top surface of the wastewater).

[0044] In some embodiments, the FMU device 100 further includes an air pump 109 for a constant air supply and a flow meter 108 for precise flow control. The air pump 109 is connected to the flow meter 108. The flow meter 108 is also called a flow controller or a flow actuator and adjusts the flow rate or pressure of the air from the air pump 109. The flow meter 108 operates by changing (e.g., adjusting) the flow rate of the air based on the measured flow rate and / or pressure of the air, and the flow meter 108 is then further connected to the air line 107, which flows into the FMU device 100, flows to the aeration ring 105A and flows to the surface of the wastewater for oxygenation. In some implementations, the amount of air passing through the flow controller can be estimated by finite element analysis, such as in Figure 3A and 3B As shown in and discussed later.

[0045] refer to Figure 1B In some embodiments, the FMU device 100 includes a support material 111 that can float on the surface of the wastewater and / or can be attached to the aeration ring 105A so that one side of the material 111 is in contact with the wastewater. The support material provides a surface area (region) for the growth of microorganisms such as bacteria. In some embodiments, the support material 111 may include but is not limited to perforated carbon fabrics, plastic meshes, perforated foams, etc., and sulfide oxidizing bacteria produce biofilms on the support material 111. In some embodiments, the support material 111 has an approximately 90% open structure. In some embodiments, the voids of the support material 111 have a circular shape with a diameter of about 1 to about 2 cm or a size of about 1 to about 4 cm. 2 In some embodiments, the biofilm of sulfide oxidizing bacteria is in direct contact with water and air at the same time.

[0046] In some embodiments, the support material 111 is placed in direct contact with the surface of the water. In some embodiments, the support material 111 floats freely on the surface of the water. In other embodiments, the support material 111 is attached to the aeration ring 105A or the aeration manifold 105B'.

[0047] For example, sulfide oxidizing bacteria can be grown on the support material 111, which ensures a higher treatment rate for the water stream and / or purification due to a higher abundance of microorganisms necessary for the treatment process.

[0048] Figure 1C An image of an exemplary FMU device 100 is shown, featuring an example of a support material 111 for bacterial growth. Figure 1C As shown in the left image of FIG. 1 , a very dense biofilm has populated the entire support material. The white color of the biofilm indicates sulfate oxidizing bacteria. Figure 1C The right image of shows the early stages of biofilm development, during which bacteria grow on the surface of the water and begin to reproduce on the support material 111.

[0049] Figure 1D and 1E Figures showing other example embodiments of FMU devices 100 for removing sulfides from water and / or wastewater bodies and streams according to the present technology. Figure 1D and 1E As shown in , in some embodiments, the aeration module 105 of the FMU device 100 includes an aeration manifold array 105B including a plurality of aeration channels. For example, the aeration manifold array 105B includes a plurality of tube structures extending (spanning) from a feed pipe, wherein the tube structure has one or more openings to allow air to flow out from the interior of the tube structure. Figure 1D and 1E In the example embodiment shown in , the aeration manifold array 105B can float on top of the wastewater storage tank 101 using a floating support 104, wherein the floating support 104 is located between the wastewater in the wastewater storage tank 101 and the aeration manifold array 105B, so that the aeration manifold array 105B is maintained above the liquid level of the wastewater storage tank 101. The aeration manifold array 105B is connected to an air line 107 to provide air to the aeration manifold. In some embodiments, the example FMU device 100 includes a support material 111, which can float on the surface of the wastewater and / or can be attached to the aeration manifold array 105B so that one side of the material 111 is in contact with the wastewater. In some embodiments, the example FMU device 100 does not include a support material 111. For example, microorganisms (e.g., bacteria) can grow on the surface of the water even without the support material 111, but the support material 111 can promote the process and develop a denser biofilm.

[0050] Figure 2A and 2BImages depicting various configurations of an exemplary FMU device 100 at different scales with and without support material 111 are shown, respectively. Figure 2A As shown in , images 201A and 201B show an example FMU device 100 without support material 111 having a diameter of approximately 30 cm. Figure 2A Images 202A-202C show an example FMU device 100 having a diameter of 30 cm with support material 111. Figure 2B As shown in FIG. 2 , image 203A shows an example FMU device 100 having a diameter of 1 m without the support material 111, while images 203B and 203C show an example FMU device 100 configured with the support material 111. For the FMU device 100 without the support material 111, bacteria will grow on the surface of the water. For the FMU device 100 with the support material 111, the support material 111 can promote the growth process of bacteria. The FMU device 100 is operable with and without the support material 111.

[0051] Figure 2C Examples of FMU devices 100 and variations in the design and size of aeration modules 105 are shown. Figure 2C As shown in Figure 2C The example aeration ring diameter designated as 205A in the example may be about 0.5 ft; Figure 2C The exemplary aeration manifold array, labeled 205B in FIG. 1 , may have multiple aeration channels of varying lengths (e.g., up to about 15 ft long, although in Figure 2C Approximately 4 ft long in the image).

[0052] In some embodiments, the FMU device 100 does not include the wastewater storage tank 101 but instead is directly integrated into an existing water and / or wastewater treatment unit. For example, the FMU device 100 may include an aeration module including an aeration ring 105A and / or an aeration manifold array 105B placed directly onto a water source not contained within the wastewater storage tank 101. Figures 1A-1C Similar to the exemplary FMU device 100 described in , the aeration ring 105A may be configured to contact the water at a specific height or not to contact the water directly due to the floating support 104 .

[0053] Figure 3A and 3B A data plot is shown depicting a flow simulation of air flow and air distribution at a water and / or wastewater surface for an example embodiment of the FMU apparatus 100. The data plot shows air velocity, diameter of aeration tubes, and number and location of holes on an aeration module determined based on the flow simulation.

[0054] Example Implementation of an FMU System for Brewery Wastewater Treatment

[0055] Figure 4 An image is shown depicting an example embodiment of an FMU device according to some embodiments of the present technology connected to an example microbial fuel cell (MFC) reactor to form an FMU-MFC system 400. The image shows the FMU-MFC system 400 configured in an example setup for an experimental implementation.

[0056] The FMU-MFC system 400 includes an FMU device 401 according to some embodiments of the FMU device 100 connected to an example embodiment of an MFC reactor 402. In an experimental implementation, the example FMU-MFC system 400 runs for more than 80 days in batch mode at a flow rate of 0.1 gallons per minute (gal / min). For example, the FMU device 401 is coupled to the MFC reactor 402 to form an example FMU-MFC system 400 for treating brewery wastewater. The system 400 includes an inflow line 404 to supply water / wastewater to the storage tank of the FMU device 401. The outflow line 403 from the FMU device 401 enters the MFC reactor 402 for removing organic matter. As shown in the image, the example FMU device 401 used in the system 400 includes an air line marked as 407 to supply air to the aeration module (placed in the container of the FMU 401, not shown). In this example embodiment, the system 400 includes a flow meter 430 and an air pump 420 connected to the FMU 401. In an implementation, for example, the FMU-MFC system 400 may be operated in a batch mode and periodically fed with raw brewery wastewater.

[0057] In some example embodiments, the MFC reactor 402 includes a housing and a bioelectrochemical reactor encapsulated in the housing. The bioelectrochemical reactor includes a plurality of anodes arranged between cathode assemblies. The cathode assembly may include at least two cathodes, which are separated on opposite sides of the plurality of anodes and arranged through the bioelectrochemical reactor along the flow direction of the fluid so that the fluid flows between the two cathodes. In some embodiments, at least two cathodes of the cathode assembly include gas diffusion cathodes that can operate to allow oxygen to permeate into the fluid in the biochemical reactor.

[0058] In the experimental implementation, the performance of the example FMU-MFC system 400 is compared with the performance of the MFC reactor 402 without the FMU device 401. The presence of sulfide in the system highly affects the operation of the MFC reactor 402. Sulfide is adsorbed on the cathode surface and reduces the catalytic activity of the catalyst. As a result, the cathode potential of the MFC reactor 402 is converted to a significantly negative value, accompanied by a significant reduction in the cathode reaction rate. Negative cathode potentials are undesirable for MFC operation.

[0059] The example results from this run demonstrate that the electrochemical performance of the FMU-MFC system 400 is very stable, with the cathode potential remaining positive.

[0060] Figure 5 The stability of the cathode potential of the FMU-MFC system 400 is shown compared to a system having only an MFC reactor 402 without an FMU device 401. Plots 500A and 500B depict the cathode potential (in mV) of the example FMU-MFC system 400 at the right cathode and left cathode of the MFC device 402, respectively, for more than 75 days of performance. Plots 502A and 502B depict the cathode potential of the right cathode and left cathode of the MFC device 402, respectively, alone (i.e., without the FMU device 401) for the same period of time.

[0061] In an example implementation of an FMU-MFC system 400 for treating brewery wastewater, the conversion rate of sulfate to dissolved sulfide is determined to be 7%. Therefore, 7% of the sulfate present in the brewery wastewater is converted to sulfide, while the remaining sulfate remains in the liquid phase. Some of the remaining sulfate is used by bacteria for protein synthesis, or is directly converted into elemental sulfur. At the same time, some of the produced sulfide is released into the atmosphere as hydrogen sulfide, while a portion of the dissolved sulfide is adsorbed on the cathode surface. Given that the conversion rate of sulfate to sulfide still in the water is 7%, it is calculated that the efficiency of the FMU device 401 used in the example FMU-MFC system 400 ranges from 74 to 100%.

[0062] Figure 6 A schematic diagram is shown illustrating an example FMU-MFC system 600 according to some embodiments of the FMU-MFC system 400. An example implementation of the example FMU-MFC system 600 is described, which is installed as a pretreatment unit in a pilot installation treating 150 gpd of brewery wastewater at a brewery located in California.

[0063] The FMU-MFC system 600 can be placed on a cart-on-wheels or other movable structure to allow the FMU-MFC system to be transportable. The FMU-MFC system 600 includes an FMU device 601 according to an exemplary embodiment of the FMU device 100, a balance (EQ) tank 602, a collection tank 603, an MFC reactor array 604 (such as shown in an array configuration in this example) and a feeder box 605. In this example, the FMU device 601 is a separate unit consisting of: a 75gal tank, an air pump according to the air pump 109, a flow meter according to the flow meter 108, an aeration module according to the aeration ring 105, and a foam support material according to the support material 111 for bacterial growth. In this example, the FMU device 601 is disposed adjacent to the EQ tank 602 and is operatively connected to the EQ tank 602; and the EQ tank 602 is adjacent to the collection tank 603. The feed box 605 is operatively connected to the FMU device 601 and the MFC reactor 604 .

[0064] In an example implementation of operating the FMU-MFC system 600, brewery wastewater flows from the EQ tank 602 into the FMU unit 601 at a flow rate of 0.1 gpm. The wastewater is then transferred from the FMU unit 601 to the system's feed tank 605, and from the feed tank 605 to the MFC reactor 604. For example, the effluent from the MFC reactor 604 flows back to the EQ tank 602 during intermittent operation and back to the collection tank 603 during continuous operation. The hydraulic residence time of the wastewater in the FMU system 600 is 4 hours. Raw wastewater is periodically introduced into the pilot FMU system 601.

[0065] Figure 7 A pilot plant diagram depicting an example FMU-MFC system 600 is shown. 2- ) and sulfide (S 2- ) data plotted over time. Plots 700A and 700B depict the concentrations of sulfide and sulfate, respectively, in brewery wastewater over 350 days of operation. Figure 7 The addition of new wastewater is indicated by arrows in the plot. As shown in the data plot, any addition of new wastewater increases the level of sulfide or sulfate. Figure 7 The data plots show that the example FMU system 601 successfully reduces or completely removes sulfate and sulfide present in the wastewater. The efficiency of the FMU unit ranges from 71 to 100%.

[0066] Example Implementation of an FMU System for Food Processing Wastewater Treatment

[0067] Fig. 8A and 8Bshows a depiction of Figure 4 Sulfate (SO4) measured by an example FMU-MFC system used in an example implementation for treating food processing wastewater 2- ) and sulfide (S 2- ) concentration versus time. Fig. 8A In FIG. 8 , plots 800A and 800B depict the concentrations of sulfide and sulfate, respectively, in the food processing wastewater over a 40-day run. Figure 8B 8, plots 802A and 802B depict the concentrations of sulfide and sulfate, respectively, in food processing wastewater for more than 25 days of operation. The example FMU-MFC system used in the example food processing wastewater treatment implementation includes an FMU device 401 connected to an MFC reactor 402, and Figure 4 Similar to that shown in .

[0068] Fig. 8A The data plots show the removal of sulfate and sulfide from an example FMU-MFC system 400 treating wastewater from tofu and pasta sauce production. The high protein content of this wastewater type caused the sulfide concentration to increase significantly to levels above 10 mg / L when the wastewater was introduced into the example FMU-MFC system. It is estimated that the FMU unit reduced the sulfide concentration by 50% and the sulfate concentration by 100%.

[0069] Figure 8B The data plots show sulfide and sulfate plots for an FMU-MFC system treating wastewater from tomato juice production. It is estimated that the FMU unit reduced sulfide concentrations by up to 90% and sulfate concentrations by 100%.

[0070] Example

[0071] In some embodiments (Example A1) according to the disclosed technology, a system for removing sulfide from a water or wastewater solution includes: a manifold structure comprising one or more openings to allow air to flow out from the interior of the manifold structure; one or more support structures connected to the manifold structure, wherein the one or more support structures are floatable on the surface of a fluid including water or a wastewater solution in a container so that the manifold structure does not contact the water or wastewater solution; and an air source that allows air to flow to the manifold structure to oxidize the sulfide on the surface of the water or wastewater solution.

[0072] Embodiment A2 includes the system of any of Embodiments A1-A18, wherein sulfide is oxidized to elemental sulfur and removed from the water or wastewater solution.

[0073] Embodiment A3 includes the system of any of Embodiments A1-A18, wherein the air source comprises a pump.

[0074] Embodiment A4 includes the system of Embodiment A3, wherein the pump is further connected to a tube that supplies air to the aeration ring.

[0075] Embodiment A5 includes the system of any of Embodiments A1-A18, further comprising a flow meter to control the rate (flow rate) of the air flow.

[0076] Embodiment A6 includes the system of any of Embodiments A1-A18, wherein the manifold structure is configured as a ring.

[0077] Embodiment A7 includes the system of any of Embodiments A1-A18, further comprising a material coupled to the manifold structure and adapted to allow growth of sulfide oxidizing bacteria.

[0078] Embodiment A8 includes the system of Embodiment A7, wherein the material comprises a perforated carbon fabric, a plastic mesh, or a perforated foam.

[0079] Embodiment A9 includes the system of Embodiment A7, wherein the material is operable to float on the surface of the water or wastewater solution.

[0080] Embodiment A10 includes the system of any of Embodiments A1-A18, wherein the one or more openings of the manifold structure provide uniform air distribution over the surface of the water or wastewater solution.

[0081] Embodiment A11 includes the system of any of Embodiments A1-A18, wherein the manifold structure comprises a flexible tube.

[0082] Embodiment A12 includes the system of any of Embodiments A1-A18, wherein the manifold structure comprises a rigid tube.

[0083] Embodiment A13 includes the system of any of Embodiments A1-A18, wherein the one or more support structures are porous, biocompatible, and / or inert in water.

[0084] Embodiment A14 includes the system of any of Embodiments A1-A18, wherein the one or more support structures comprise foam.

[0085] Embodiment A15 includes the system of any of Embodiments A1-A18, wherein the water or wastewater solution is stored in a tank.

[0086] Embodiment A16 includes the system of Embodiment A15, wherein the tank is connected to a feed line through which fluid can flow into the container and an outlet line through which water and wastewater can flow out of the container once treated.

[0087] Embodiment A17 includes the system of any of Embodiments A1-A18, wherein the manifold structure, one or more support structures, and the air source are contained within (one) unit.

[0088] Embodiment A18 includes the system of any preceding Embodiments A1-A17, wherein the water or wastewater solution comprises waste received from a civil infrastructure system, an agricultural system, or an industrial system.

[0089] In some embodiments (Example B1) of the disclosed technology, a system for removing sulfide from water or wastewater includes: a manifold structure comprising one or more openings to allow air to flow out from the interior of the manifold structure; one or more support structures connected to the manifold structure, wherein the one or more support structures are floatable on the surface of a fluid comprising water or wastewater; and an air source configured to supply air to the manifold structure so that the air flows out of the manifold structure through one or more openings located at the fluid to promote oxidation of sulfide in the fluid, wherein the air flowing out from the internal manifold structure includes oxygen in an amount containing less than 0.1 mg / L oxygen (O2).

[0090] Embodiment B2 includes the system of any of Embodiments B1-B25, wherein the system is operable to flow air at a top surface of the fluid to a shallow depth within the range of 0 cm to 5 cm within the fluid.

[0091] Embodiment B3 includes the system of any of Embodiments B1-B25, wherein the manifold structure includes a plurality of channels for allowing air to flow out of the interior of the manifold structure.

[0092] Embodiment B4 includes the system of any of Embodiments B1-B25, wherein sulfide is oxidized to elemental sulfur and removed from the water or wastewater solution.

[0093] Embodiment B5 includes the system of any of Embodiments B1-B25, wherein the air source comprises a pump.

[0094] Embodiment B6 includes the system of any of Embodiments B1-B25, wherein the pump is further connected to a tube that supplies air to the manifold structure.

[0095] Embodiment B7 includes the system of any of Embodiments B1-B25, wherein the system further comprises a flow meter to control the rate (flow rate) of the air flow.

[0096] Embodiment B8 includes the system of any of Embodiments B1-B25, wherein the manifold structure is configured as a ring or a polygon.

[0097] Embodiment B9 includes the system of any of Embodiments B1-B25, wherein the manifold structure is configured as a plurality of tube structures extending from the feed tube, wherein the tube structures have one or more openings to allow air to flow out from the interior of the tube structures.

[0098] Embodiment B10 includes the system of any of Embodiments B1-B25, wherein the system further comprises a support material coupled to the manifold structure to promote growth of sulfide oxidizing bacteria to produce a biofilm.

[0099] Embodiment B11 includes the system of any of Embodiments B1-B25, wherein the support material comprises a perforated carbon fabric, a plastic mesh, or a perforated foam.

[0100] Embodiment B12 includes the system of any of Embodiments B1-B25, wherein the support material is operable to float on the surface of a fluid.

[0101] Embodiment B13 includes the system of any of Embodiments B1-B25, wherein the support material comprises a plurality of openings such that the support material has an open structure of up to 90% of the structure.

[0102] Embodiment B14 includes the system of any of Embodiments B1-B25, wherein the one or more openings of the manifold structure are configured to provide uniform air distribution over a surface of a fluid comprising water or wastewater.

[0103] Embodiment B15 includes the system of any of Embodiments B1-B25, wherein the manifold structure comprises a flexible tube.

[0104] Embodiment B16 includes the system of any of Embodiments B1-B25, wherein the manifold structure comprises a rigid tube.

[0105] Embodiment B17 includes the system of any of Embodiments B1-B25, wherein the one or more support structures are porous, biocompatible, and / or inert in water.

[0106] Embodiment B18 includes the system of any of Embodiments B1-B25, wherein the one or more support structures comprise foam.

[0107] Embodiment B19 includes the system of any of Embodiments B1-B25, wherein the system comprises a container for storing a fluid.

[0108] Embodiment B20 includes the system of any of Embodiments B1-B25, wherein the container is connected to a feed line through which fluid can flow into the container and an outlet line through which fluid can flow out of the container once processed.

[0109] Embodiment B21 includes the system of any of Embodiments B1-B25, wherein the manifold structure is elevated above the fluid by one or more support structures such that one or more openings of the manifold structure are not in contact with the fluid.

[0110] Embodiment B22 includes the system of any of Embodiments B1-B25, wherein the manifold structure, one or more support structures, and the air source are housed within a single unit.

[0111] Embodiment B23 includes the system of any of Embodiments B1-B25, wherein the water or wastewater comprises waste received from a civil infrastructure system, an agricultural system, or an industrial system.

[0112] Embodiment B24 includes the system of any of Embodiments B1-B25, wherein the fluid comprising water or wastewater is contained within the vessel and the one or more support structures are buoyant on a surface of the fluid in the vessel.

[0113] Embodiment B25 includes the system of any of Embodiments B1-B24, wherein the system is configured to feed an output fluid from the system to a microbial fuel cell (MFC) reactor.

[0114] In some embodiments (Example B26) according to the disclosed technology, a method for removing sulfide from a fluid containing water or wastewater includes: contacting the fluid containing water or wastewater with a manifold structure, the manifold structure including one or more openings to allow air to flow out from the interior of the manifold structure, wherein the manifold structure is positioned relative to the fluid based on one or more support structures, the one or more support structures being connected to the manifold structure and configured to float on the fluid; allowing air to flow out from the interior of the manifold structure to supply oxygen gas containing an amount of less than 0.1 mg / L oxygen (O2) to the fluid; and converting sulfide of the fluid into elemental sulfur.

[0115] Embodiment B27 includes the method of any one of Embodiments B26-B36, wherein the fluid comprises sulfide oxidizing bacteria.

[0116] Embodiment B28 includes the method of any one of Embodiments B26-B36, wherein causing air to flow from the interior of the manifold structure comprises supplying an amount of oxygen containing less than 0.1 mg / L of O2 at a shallow depth within a range of 0 cm to 5 cm within the fluid at the top surface of the fluid.

[0117] Embodiment B29 includes the method of any one of Embodiments B26-B36, comprising regulating the flow of air with a flow meter so that air flows out from the interior of the manifold structure.

[0118] Embodiment B30 includes the method of any of Embodiments B26-B36, wherein the air stream is adjusted so that the concentration of oxygen introduced into the fluid containing water or wastewater does not exceed about 0.1 mg / L.

[0119] Embodiment B31 includes the method of any one of Embodiments B26-B36, comprising providing a support material coupled to a manifold structure to promote growth of sulfide oxidizing bacteria on the support material to produce a biofilm.

[0120] Embodiment B32 includes the method of any one of Embodiments B26-B36, wherein the method does not convert the sulfide to sulfate, thiosulfate, or a combination thereof.

[0121] Embodiment B33 includes the method of any one of Embodiments B26-B36, wherein the sulfide is hydrogen sulfide.

[0122] Embodiment B34 includes the method of any of Embodiments B26-B34 or B36, wherein the manifold structure is elevated above the fluid by one or more support structures such that the one or more openings of the manifold structure are not in contact with the fluid.

[0123] Embodiment B35 includes the method of any one of Embodiments B26-B34 or B36, wherein the manifold structure is positioned relative to the fluid by one or more support structures such that one or more openings of the manifold structure contact the fluid at a surface of the fluid or are at least partially immersed in the fluid.

[0124] Embodiment B36 includes the method of any one of Embodiments B26-B35, wherein the method is performed by the system of any one of Embodiments B1-B25, by the system of any one of Embodiments A1-A18, by the device of any one of Embodiments C1-C15, or by the system of any one of Embodiments D1-D8.

[0125] In some embodiments (Example C1) of the disclosed technology, an apparatus for removing sulfide from water or wastewater comprises: a manifold structure comprising one or more openings to allow air to flow out from the interior of the manifold structure; one or more support structures connected to the manifold structure, wherein the one or more support structures are floatable on the surface of a fluid comprising water or wastewater; and an air source configured to supply air to the manifold structure so that the air flows out of the manifold structure through one or more openings located at the fluid to promote oxidation of sulfide in the fluid, wherein the air supplied by the air source to the manifold structure comprises oxygen in an amount containing less than 0.1 mg / L oxygen (O2).

[0126] Embodiment C2 includes the device of any of Embodiments C1-C15, wherein the device is operable to flow air at a top surface of the fluid to a shallow depth within the range of 0 cm to 5 cm within the fluid.

[0127] Embodiment C3 includes the device of any of Embodiments C1-C15, wherein the manifold structure comprises a plurality of channels for allowing air to flow out of the interior of the manifold structure.

[0128] Embodiment C4 includes the device of any of Embodiments C1-C15, wherein the air source comprises a pump connected to a tube that supplies air to the manifold structure.

[0129] Embodiment C5 includes the device of any of Embodiments C1-C15, further comprising a flow meter to control the rate (flow rate) of the air flow.

[0130] Embodiment C6 includes the device of any of Embodiments C1-C15, wherein the manifold structure is configured to have a ring-shaped geometry or a polygonal geometry.

[0131] Embodiment C7 includes the device of any of Embodiments C1-C15, wherein the manifold structure comprises a plurality of tubular structures extending from a feed tube, wherein the tubular structures have one or more openings to allow air to flow out from the interior of the tubular structures.

[0132] Embodiment C8 includes the device of any one of embodiments C1-C15, further comprising a support material coupled to the manifold structure to promote the growth of sulfide oxidizing bacteria on the support material to produce a biofilm, wherein the support material includes a plurality of openings such that the support material has an open structure of up to 90% of the structure.

[0133] Embodiment C9 includes the device of any of Embodiments C1-C15, wherein the support material comprises a perforated carbon fabric, a plastic mesh, or a perforated foam.

[0134] Embodiment C10 includes the device of any of Embodiments C1-C15, wherein the support material is configured to float on a surface of the fluid.

[0135] Embodiment C11 includes the device of any of Embodiments C1-C15, wherein the one or more support structures are porous, biocompatible, and / or inert in water.

[0136] Embodiment C12 includes the device of any of Embodiments C1-C15, wherein the one or more support structures comprises foam.

[0137] Embodiment C13 includes the device described in any one of embodiments C1-C15, which includes a container to store the fluid, wherein the container is connected to a feed pipeline and a discharge pipeline, and the fluid can flow into the container through the feed pipeline, and the fluid can flow out of the container through the discharge pipeline once it is processed.

[0138] Embodiment C14 includes the device of any of Embodiments C1-C15, wherein the manifold structure is elevated above the fluid by one or more support structures such that the one or more openings of the manifold structure are not in contact with the fluid.

[0139] Embodiment C15 includes the device of any of Embodiments C1-C14, wherein the one or more openings of the manifold structure are configured to provide uniform air distribution over a surface of the fluid.

[0140] In some embodiments (Example D1) of the disclosed technology, a system for removing sulfide from wastewater and treating wastewater includes: a container configured to store a fluid including wastewater, wherein the container is connected to a feed line and a discharge line, the fluid can flow into the container through the feed line, and the fluid can flow out of the tank as a pretreated fluid through the discharge line once it is pretreated; a micro-aeration device configured to float on the fluid, the micro-aeration device comprising (i) a manifold structure including one or more openings to allow air to flow out from the interior of the manifold structure, (ii) one or more support structures connected to the manifold structure, wherein the one or more support structures are buoyant on the surface of the fluid, and (iii) an air source configured to supply air to the manifold structure so that the air passes through one or more support structures located at the fluid. an opening flowing out from a manifold structure to promote conversion of sulfide in the fluid to elemental sulfur to produce a treated fluid, wherein air supplied to the manifold structure by an air source includes oxygen in an amount containing less than 0.1 mg / L oxygen (O2); and a microbial fuel cell (MFC) device configured to receive the pretreated fluid via a discharge line, the MFC device being configured to bioelectrochemically process the pretreated fluid to simultaneously generate electrical energy and digest organic matter in the pretreated fluid to produce treated water, wherein the MFC device comprises a housing and a bioelectrochemical reactor enclosed in the housing, wherein the bioelectrochemical reactor comprises a plurality of anodes arranged between a cathode assembly, the cathode assembly comprising two cathodes separated on opposite sides of the plurality of anodes and arranged along a flow direction of the pretreated fluid.

[0141] Embodiment D2 includes the system of any of embodiments D1-D8, wherein the micro-aeration device is operable to flow air at a top surface of the fluid to a shallow depth within a range of 0 cm to 5 cm within the fluid.

[0142] Embodiment D3 includes the system of any one of embodiments D1-D8, wherein the micro-aeration device further comprises a flow meter to control the rate (flow rate) of the air flow.

[0143] Embodiment D4 includes the system of any one of Embodiments D1-D8, wherein the micro-aeration device further comprises a support material coupled to the manifold structure to promote the growth of sulfide oxidizing bacteria to produce a biofilm, wherein the support material comprises a plurality of openings such that the support material has an open structure of up to 90% of the structure.

[0144] Embodiment D5 includes the system of any of Embodiments D1-D8, wherein the manifold structure comprises a plurality of channels to allow air to flow out of the interior of the manifold structure.

[0145] Embodiment D6 includes the system of any of Embodiments D1-D8, wherein the manifold structure is configured to have a ring-shaped geometry or a polygonal geometry.

[0146] Embodiment D7 includes the system of any of Embodiments D1-D8, wherein the manifold structure comprises a plurality of tubular structures extending from the feed tube, wherein the tubular structures have one or more openings to allow air to flow out of the interior of the tubular structures.

[0147] Embodiment D8 includes the system of any of Embodiments D1-D8, wherein both cathodes of the cathode assembly comprise gas diffusion cathodes operable to allow oxygen to permeate into a fluid within the biochemical reactor.

[0148] Further example implementations according to the present technology are described.

[0149] In some embodiments, a floating micro aeration (FMU) system for removing sulfide from a water and / or wastewater solution comprises: (a) a tank having inflow and outflow lines for receiving raw wastewater; (b) a FMU device, an air pump for providing air flow at a constant rate, and a flow meter to control the air flow.

[0150] In some embodiments of the system, the FMU device comprises an air ring or manifold, a floating support and a perforated foam material. In some embodiments of the system, the FMU device is further connected to an air pump with a spiral tube. In some embodiments of the system, a flow meter is used to control the air flow to the FMU device. In some embodiments, the FMU system includes an air ring or manifold that provides uniform air distribution on the surface of the water. The air ring or manifold provides uniform air distribution by combining holes on the side of the air ring or manifold, allowing air to escape from the FMU system. In some embodiments, the air ring or manifold are flexible or rigid tubes. In some embodiments, the floating support is a highly porous biocompatible foam material that is inert in water. In some embodiments, the foam material provides surface area for bacterial growth, and / or floats on the surface of the water. In some embodiments, wastewater comprises the waste received from a civil infrastructure system, an agricultural system or an industrial system.

[0151] The specification together with the drawings is intended to be considered as exemplary only, wherein exemplary means an example. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. In addition, the use of "or" is intended to include "and / or", unless the context clearly indicates otherwise.

[0152] Although this patent document contains a number of specifics, these should not be construed as limitations on the scope of any invention or claim, but rather as descriptions of features that are specific to a particular embodiment of a particular invention. Certain features described in the context of separate embodiments in this patent document may also be implemented in combination in a single embodiment. Conversely, different features described in the context of a single embodiment may also be implemented separately in multiple embodiments or in any suitable sub-combination. In addition, although features may be described above as being implemented in certain combinations and may even be initially required, in some cases one or more features from the required combination may be removed from the combination, and the required combination may involve a sub-combination or a variation of the sub-combination.

[0153] Similarly, although operations are depicted in a particular order in the drawings, this should not be understood as requiring that such operations be performed in the particular order shown or in an orderly order, or that all illustrated operations be performed, in order to achieve the desired results. In addition, the separation of different system components in the embodiments described in this patent document should not be understood as requiring such separation in all embodiments.

[0154] Only a few implementations and embodiments are described, and other implementations, enhancements, and variations may be made based on what is described and illustrated in this patent document.

Claims

1. A system for removing sulfide from water or wastewater, comprising: a manifold structure including one or more openings to allow air to flow from an interior of the manifold structure; one or more support structures connected to the manifold structure, wherein the one or more support structures are configured to float on a surface of a fluid including water or wastewater or to allow the manifold structure to be partially submerged below the surface of the fluid; and an air source configured to supply air to the manifold structure so that the air flows out of the manifold structure through the one or more openings located at the fluid to promote sulfide oxidation in the fluid, wherein the device is configured to discharge air from the one or more openings of the manifold structure (i) at the top surface of the fluid, (ii) at a shallow depth within the range of 0 cm to 5 cm below the top surface of the fluid, or (iii) at the top surface of the fluid and at the shallow depth, so that the air flowing out of the internal manifold structure supplies oxygen in an amount containing less than 0.1 mg / L oxygen (O2) at the shallow depth of the fluid, and Therein, the sulfides are oxidized to elemental sulfur and removed from the water or wastewater solution.

2. The system of claim 1, wherein the manifold structure includes a plurality of channels for allowing air to flow out from an interior of the manifold structure.

3. The system of claim 1 or 2, wherein the air source comprises a pump.

4. The system of claim 3, wherein the pump is connected to a tube that supplies air to the manifold structure.

5. The system of claim 1 or 2, further comprising: Flow meter to control air flow rate.

6. The system of claim 1 or 2, wherein the manifold structure comprises an annular geometry or a polygonal geometry.

7. The system of claim 1 or 2, wherein the manifold structure comprises a plurality of tube structures extending from the feed tube, wherein the one or more openings are disposed on the tube structures to allow air to flow out from the interior of the tube structures.

8. The system of claim 1 or 2, further comprising: A support material coupled to the manifold structure to promote the growth of sulfide oxidizing bacteria to produce a biofilm.

9. The system of claim 8, wherein the support material comprises perforated carbon fabric, plastic mesh, or perforated foam.

10. The system of claim 8, wherein the support material is configured to float on a surface of the fluid.

11. The system of claim 8, wherein the support material comprises a plurality of openings such that the support material has an open structure of up to 90% of the structure.

12. The system of claim 1 or 2, wherein the one or more openings of the manifold structure are configured to provide uniform air distribution over a surface of the fluid.

13. The system of claim 1 or 2, wherein the manifold structure comprises a flexible tube.

14. The system of claim 1 or 2, wherein the manifold structure comprises a rigid tube.

15. The system of claim 1 or 2, wherein the one or more support structures are porous, biocompatible, and / or inert in water.

16. The system of claim 1 or 2, wherein the one or more support structures comprise foam.

17. The system of claim 1 or 2, comprising: Container to store fluid.

18. The system of claim 17, wherein the vessel is connected to a feed line through which fluid can flow into the vessel and an outlet line through which fluid can flow out of the vessel once processed.

19. The system of claim 1 or 2, wherein the manifold structure is elevated above the fluid by the one or more support structures such that the one or more openings of the manifold structure are not in contact with the fluid.

20. The system of claim 1 or 2, wherein the manifold structure, the one or more support structures, and the air source are housed within a single unit.

21. The system of claim 1 or 2, wherein the water or wastewater comprises waste received from a civil infrastructure system, an agricultural system, or an industrial system.

22. The system of claim 1 or 2, wherein a fluid comprising water or wastewater is contained within a vessel, and the one or more support structures are buoyant on a surface of the fluid in the vessel.

23. The system of claim 1 or 2, wherein the system is configured to supply an output fluid from the system to a microbial fuel cell (MFC) reactor.

24. A method for removing sulfides from a fluid containing water or wastewater, the method comprising: contacting a fluid comprising water or wastewater with a manifold structure, the manifold structure comprising one or more openings to allow air to flow out of an interior of the manifold structure, wherein the manifold structure is positioned relative to the fluid based on one or more support structures connected to the manifold structure and configured to float on a surface of the fluid or to partially submerge the manifold structure below a surface of the fluid; (i) at the top surface of the fluid, (ii) at a shallow depth within the range of 0 cm to 5 cm below the top surface of the fluid, or (iii) at the top surface of the fluid and at said shallow depth, causing air to flow from the interior of the manifold structure to supply oxygen gas in an amount containing less than 0.1 mg / L oxygen (O2) to the fluid within said shallow depth of the fluid, thereby promoting sulfide oxidation in the fluid; and Converts the sulfides of the fluid into elemental sulfur.

25. The method of claim 24, wherein the fluid comprises sulfide oxidizing bacteria.

26. A method as claimed in claim 24 or 25, comprising regulating the flow of air with a flow meter so that air flows out from the interior of the manifold structure.

27. The method of claim 26, wherein the air stream is adjusted so that the concentration of oxygen introduced into the fluid containing water or wastewater does not exceed about 0.1 mg / L.

28. The method of claim 24 or 25, comprising providing a support material coupled to the manifold structure to promote growth of sulphide oxidizing bacteria on the support material to produce a biofilm.

29. The method of claim 24 or 25, wherein the method does not convert sulfide to sulfate, thiosulfate, or a combination thereof.

30. The method of claim 24 or 25, wherein the sulfide is hydrogen sulfide.

31. The method of claim 24 or 25, wherein the manifold structure is elevated above the fluid by the one or more support structures such that the one or more openings of the manifold structure are not in contact with the fluid.

32. The method of claim 24 or 25, wherein the manifold structure is positioned relative to the fluid by the one or more support structures so that the one or more openings of the manifold structure are in contact with the fluid at a surface of the fluid or are at least partially immersed in the fluid.

33. The method of claim 24 or 25, wherein the method is implemented by the system of any one of claims 1 to 23.

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