WO2010096457A2 - Modular wastewater treatment system and method - Google Patents

Abstract

A modular secondary wastewater treatment system includes one or more dedicated vessels that perform a single secondary wastewater treatment operation. The reactor vessels may be made by converting standard intermodal transport containers for this purpose. The containers are stood on end with the front of the container forming the bottom of the vessel. Openings in the sidewalls of the vessels are piped to one another to establish the series and parallel flow paths desired for the modular system. The modular system allows for easy and standardized design, transport, set up and operation, with inherent scaling.

Description

MODULAR WASTEWATER TREATMENT SYSTEM AND

METHOD

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a Nonprovisional Patent Application of US Provisional Patent Application No. 61/154,211, entitled "Modular Wastewater Treatment System and Method", filed February 20, 2009, which is herein incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

[0002] The present invention relates generally to wastewater treatment systems. More particularly, the invention relates to a modular secondary wastewater treatment system that can be easily transported, set up on location, and operated in a modular fashion, allowing for adaptation to a range or conditions, mass flow rates, treatment needs, and so forth.

[0003] A wide range of wastewater treatment systems have been developed and are presently in use. Most of these systems are large and service municipalities or industries in specific locations, occupying considerable real estate. Depending upon the wastewater treatment technology employed, the systems may include primary treatment, secondary treatment, and tertiary treatment. The type and degree of treatment in each of these stages may commonly depend upon local regulations, the source and degree of contamination of the wastewater, and the ultimate intended use of the wastewater after treatment. Many locations throughout the world could benefit from improved wastewater treatment, however, but cannot afford the investment in large traditional installations. Moreover, many applications exist for wastewater treatment in locations that are either remote or temporary, again rendering traditional large installations impractical.

[0004] Attempts have been made to devise transportable wastewater treatment plants to address such needs. Such systems have, however, typically taken a packaged approach to system design, in which all components of the system may be included in a single container or system assembly. For example, multiple reactors, pumps, motors, valving, piping, and so forth have been pre-assembled in shipping containers that can be moved from on place to another and easily set up to treat wastewater at the location. While these systems are useful for some applications, they are often inadequately sized or scaled for any particular application. That is, the throughput requirements of various applications may vary considerably, rendering units either too small or too large for the actual needs. Moreover, the system configuration is generally fixed, and various types of reactor vessels, flow configurations, and so forth generally cannot be readily adapted once the systems have been assembled.

[0005] There is a need, therefore, for improved techniques for wastewater treatment that offer a greater degree of flexibility in system design, assembly, and transport

BRIEF DESCRIPTION OF THE INVENTION

[0006] The present invention provides a modular secondary wastewater treatment system designed to respond to such needs. The system may be configured in a variety of manners, based upon individual containers that form vessels used for various wastewater treatment reactions. Each vessel performs a dedicated reaction, and therefore serves as a reactor for only one of the wastewater treatment processes in any particular installation. The reactor vessels may perform, for example, biochemical oxygen demand reduction operations, nitrification operations, denitrification operations, surge control, and so froth. While each containerized reactor vessel performs only one such operation, more than one vessel performing these operations may be provided in a system. The containerized reactor vessels may be piped to one another for the series or parallel flow necessary in the desired process, and the vessels may be linked to one another physically to provide a modular system that can be easily scaled up or down and that offers a greatly reduced footprint as compared to other systems. [0007] The containerized reactor vessels may be adapted from conventional intermodal transport containers. The containers may be fortified to withstand static head pressures in operation, and openings may be formed in the containers to easily adapt piping once on location. Support systems, such as mixing tubes, aeration assemblies, biological support media, and so forth may be provided in the containers and may be preassembled with a container before shipping or may be assembled in the container on location. The containers may all be similar, such that any container could be used for any particular wastewater treatment operation once the containers are installed, assembled with support equipment, and piped to one another.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[0009] FIG. 1 is a diagrammatical overview of an exemplary modular wastewater treatment system in accordance with aspects of the present invention;

[0010] FIG. 2 is a diagrammatical perspective view of a series of containerized reactor vessels assembled for modular secondary wastewater treatment in the system of FIG. 1;

[0011] FIG. 3 is a similar modular secondary wastewater treatment system including two vessels that perform similar operations;

[0012] FIG. 4 is a further embodiment of a modular secondary wastewater treatment system including multiple containerized reactor vessels and a catwalk for servicing the vessels;

[0013] FIG. 5 is a perspective view of an exemplary intermodal transport container adapted for use as a containerized reactor vessel for the systems of the previous figures; [0014] FIG. 6 is a side view of the containerized reactor vessel of FIG. 5;

[0015] FIG. 7 is a rear view of the containerized reactor vessel of FIG. 5;

[0016] FIG. 8 is a detailed perspective view of an exemplary flanged opening for the containerized reactor vessel;

[0017] FIG. 9 is a diagrammatical representation of components of three containerized reactor vessels adapted to perform secondary wastewater treatment operations;

[0018] FIG. 10 is a diagrammatical representation of a portion of a containerized reactor vessel with doors separated to allow venting;

[0019] FIG. 11 is a similar diagrammatical representation of a containerized reactor vessel with forced venting in the container doors;

[0020] FIG. 12 is a diagrammatical representation of an exemplary draft-mixing assembly for use in a secondary wastewater treatment operation; and

[0021] FIG. 13 is a diagrammatical representation of exemplary steps for making, transporting and installing modular secondary wastewater treatment reactor vessels in accordance with aspects of the present technique.

DETAILED DESCRIPTION OF THE INVENTION

[0022] FIG. 1 is a diagrammatical illustration of a modular wastewater treatment system employing aspects of the present techniques. In the illustrated arrangement, the system 10 receives raw wastewater 12 for treatment. The raw wastewater is deposited in a receiving station 14, for example, a portable or stationary reservoir. The wastewater is then transmitted to a primary treatment station 16, where certain operations such as screening, grit removal, and so forth may be performed. In certain embodiments of the invention, the primary wastewater treatment may be dispensed with and the wastewater may be provided directly to a modular secondary wastewater treatment system 18. Details of the secondary wastewater treatment system are provided throughout the following discussion. However, in general, the secondary treatment system may include one or multiple containerized reactors used to remove organics from the wastewater, and may employ reactor vessels designed to perform or encourage biological and chemical reactions, such as conversion of ammonia to nitrates and nitrites, denitrification, and so forth. After secondary wastewater treatment, the wastewater may be advanced to downstream components and systems, such as a dissolved air flotation system as indicated by reference numeral 20 in FIG. 1. As will be appreciated by those skilled in the art, other downstream equipment and systems may be used with or instead of the dissolved air flotation system, and the wastewater may be further treated by tertiary treatment methods, such as filtration. Ultimately, the effluent wastewater 22 is made available for various purposes, depending upon the nature and extent of the treatment, local regulations, and the ultimate use envisaged for the wastewater.

[0023] FIG. 2 is a diagrammatical illustration of an exemplary physical arrangement for components of the modular secondary wastewater treatment system 18 illustrated in FIG. 1. As noted above, the modular secondary wastewater treatment system 18 includes a number of reactor vessels as indicated by reference numerals 24, 26, 28 and 30. Each of the reactor vessels is designed and installed in the system to perform a specific secondary wastewater treatment operation, and only one operation. Wastewater may be deposited into and inspected in each of the vessels via an open upper end 32 (which may be closed by doors or panels as described below). Sidewalls of each vessel, indicated by reference numeral 34, along with the bottom of the vessel enclose an inner volume. Openings are formed in the sidewall to permit the communication of wastewater into and out of each reactor. In particular, in the illustrated embodiment, two upper openings 36 are provided at a location near the open upper end, while lower openings 38 are provided near the bottom of each reactor vessel. The openings that are not in use in accordance with any current installation of the vessels will typically be closed, such as by a blind flange cover. Piping 40 is used to communicate wastewater between each of the vessels, such that the modular secondary wastewater treatment system progressively treats wastewater introduced into the first reactor vessel 24, as indicated by reference numeral 12'. As described more fully below, some wastewater, sludge, or a combination may be recirculated to the inlet of the system for further processing. Accordingly, a recirculation pump 42 may be provided for this purpose.

[0024] It should be noted that, while not shown in the figures, one or more drains may be provided in the containerized reactors for draining wastewater when needed. For example, for servicing the system, a drain port may be provided in a lower region of the side walls through which water may be drained. In a presently contemplated embodiment, a 2 inch screen port will be provided for this purpose.

[0025] FIG. 3 illustrates an alternative configuration in which two vessels perform substantially the same function in the system. In this case, vessel 30 serves as a surge control vessel, and additional capacity is provided by a further vessel 44. Vessel 44 may be identical to the other containerized vessels, but merely serves to add capacity to the system. Accordingly, rather than being linked to vessel 30 in series, piping 46 couples the two vessels generally in parallel, thus adding to the system residence time and surge capacity in this embodiment. It should be noted, however, that any number of the individual reactor vessels may be linked in a similar manner to scale up the capacity of the particular secondary wastewater treatment operation performed in the specific reactor vessels. For example, where additional capacity or residence time is desired for any particular operation, that particular vessel may be replicated and the similarly operating vessels linked in parallel. It should be noted that such connections may include any number of conduits, including conduits at lower locations as shown in FIG. 3, at upper locations, between upper locations and lower locations, around containers to others locations adjacent, and so forth.

[0026] FIG. 4 illustrates such an arrangement in which a number of reactor vessels are arranged together and piped to one another in a matrix-like configuration. For the purposes of the embodiment of FIG. 4, the vessels are arranged in a first row 48 and a second row 50, with each reactor performing functions similar to those illustrated in FIG. 2, but with multiple reactors performing each individual secondary wastewater treatment operation. The vessels may be linked physically to one another and additional equipment, piping, and so forth may be provided above or between the vessels. In the illustrated embodiment, a catwalk 52 is disposed above the rows 48 and 50 of reactor vessels for service and inspection purposes. Again, any number of such vessels could be associated with one another, physically linked to one another, piped to perform the various wastewater treatment operations in a modular, scalable manner. At the same time, it should be borne in mind that each reactor vessel performs a single operation in the wastewater treatment process, such that complete freedom is available for use of each reactor vessel for any desired operation. Other possible configurations include 4 containerized reactor vessels arranged in a square, piping between the vessels being routed between adjacent walls (inside-facing walls) of the arranged containers, or outside the arrangement (outside-facing walls).

[0027] In accordance with certain aspects of presently contemplated embodiments, each reactor vessel is adapted from a standard intermodal transport container (sometimes referred to as a shipping container). As will be appreciated by those skilled in the art, a number of such shipping containers are commonly available and are standardized by the International Organization for Standards (ISO). ISO standard containers include nominal 20 ft. and nominal 40 ft. containers, with different heights and widths being available in each standard size. In a presently contemplated embodiment, the vessels are made from standard 20 ft. intermodal transport containers that have been reinforced, and adapted for this purpose. In the embodiment illustrated in FIG. 5, for example, each container 54 has a closed front end 56 and an open rear end 58 which may be closed by doors (see below). Openings or apertures 60 are formed in at least one of the sidewalls for receiving an inflow of wastewater to be treated and for allowing the outflow of treated wastewater. The sidewalls of each container, along with the closed front end form into a volume 62 which will be generally sealed at joint locations between these elements.

[0028] FIG. 6 illustrates the same adapted container in side view. The openings 60 will typically be flanged openings, and the openings are provided near the closed front end 56 of the container and near the open rear end, with the former ultimately forming the lower openings 38, and the latter forming the upper openings 36 once the containerized reactor vessel is placed in service. FIG. 7 illustrates the end of the same container closed by doors 64, which may be standard container doors. Openings 66, which again may be flanged openings, may be provided in each door to allow for ventilation of the reactor vessel in service, as described below.

[0029] FIG. 8 is a detailed representation of one of the flanged openings 60 in the container sidewall. As shown, the opening includes a flange interface 68 which is welded into an opening formed in the container wall. The welds seal the joint between the flange interface 68 and the container wall, to allow for sealed interfacing of piping connected to each flange interface. In the illustrated embodiment, bolts 70 are provided in a round pattern around an aperture 72. After construction, and during transport, each flange interface can receive a blind flange cover (e.g., a disc with holes matching the bolt pattern) that covers and that seals each opening. As noted above, when each containerized reactor vessel is placed in use, openings not being piped may retain this seal cover. Other types of flanges and flanged openings may be provided for, including flanges having more or fewer bolts, flanges having holes for receiving bolts, and so forth.

[0030] An exemplary secondary wastewater treatment arrangement of reactor vessels is illustrated in FIG. 9. As will be appreciated by those skilled in the art, the secondary wastewater treatment system may include only reactor vessels performing dedicated removal of organics, sometimes referred to as biochemical oxygen demand reduction. However, in the illustrated embodiment, the system also performs nitrification (conversion of ammonia to nitrates and nitrites) and denitrification. In particular, the system illustrated in FIG. 9 receives inlet flow 74, such as from a primary wastewater treatment system or sewer lift station, as well as recirculation flow 76 as described below. The inlet and recirculation flows are introduced into a draft/mixing assembly 78. Supports 80 and 82 are provided in the containerized reactor vessel and bracing 84 serves to support the draft/mixing assembly 78.

[0031] In a presently contemplated embodiment, all containerized reactor vessels are converted in the same manner, such that supports for any range of internal structures and systems are standard. Thus, any converted container may serve as a dedicated reactor vessel for any particular secondary wastewater treatment operation, and similar supports 80 are provided in each vessel. The vessels may be made different from one another, however, and some of the features may be specifically adapted for a particular type of wastewater treatment operation. The supports may include, for example, angle iron that is welded to the internal surface of the container and that protrudes inwardly to support various structures mounted thereon. The vessels may also include structural reinforcements, such as gussets, plating, supports, and so forth to rigidify and reinforce the vessels to withstand static loads (pressure head) resulting from filling the containers during use. For a standard 20 ft. intermodal transport container, for example, a water level of 15-18 ft. may be envisaged, resulting in a pressure near the bottom of the vessel of approximately 0.5 bar.

[0032] Returning to FIG. 9, the first reactor vessel 24 is designed to perform denitrification. As will be appreciated by those skilled in the art, such operations are typically performed when a total nitrogen limit of effluent is imposed, such as by regional requirements and operational design goals. In the illustrated embodiment, a water level is maintained above a recirculation opening in the draft/mixing assembly 78 and biological support media 86 is disposed in the vessel to support biological growth. The media circulates in the reactor vessel, particularly as a result of movement of the inlet flow 74 and recirculation flow 76. A screen or strainer, as illustrated generally by reference numeral 88 serves to prevent the media from flowing out of the vessel (other openings being covered by flanged covers, not represented). Wastewater is drawn from vessel 24 and sent to vessel 26 by a conduit between the vessels.

[0033] In this embodiment, reactor vessel 26 performs a dedicated biochemical oxygen demand (BOD) reduction operation. A liquid level is maintained in vessel 26 near the location of the upper openings of the vessel, and a backflow preventer or check valve 90 is provided, such as a valve manufactured by Tideflex Technologies of Carnegie, Pennsylvania, U.S.A. As will be appreciated by those skilled in the art, the backflow preventer serves to allow flow from vessel 24 into vessel 26, while preventing backflow from vessel 26 into vessel 24, such as if vessel 24 is partially or fully drained. The BOD operation is also conducted in the presence of biological support media 86, and the growth on the media is oxygenated and circulated in the vessel by air flowing from an aeration assembly 92. In the illustrated embodiment, the aeration assembly 92 includes a series of tubes or pipes supported on supports 80 near the bottom of the vessel. Air is introduced into the aeration assembly 92 from a blower 94 coupled to the aeration assembly by appropriate tubing or piping. As in the case of vessel 24, the media is retained in vessel 26 and prevented from leaving the vessel by a strainer adjacent to one of the lower openings of the vessel. Wastewater can then be removed from vessel 26 to reactor vessel 28 as illustrated. It should be noted that certain reactors may not require the addition of air (or oxygen), so that mixing may be performed by pulsed aeration or by a mixer. Moreover, it should be noted that other mixing and circulation mechanisms may be employed, such as pulsed air, mechanical mixers, and so forth.

[0034] Continuing with the embodiment illustrated in FIG. 9, vessel 28 is here designed to perform a nitrification operation in which ammonia is converted to nitrate and nitrite at a desired level (e.g., 3 mg/lt). The flow from vessel 26 to vessel 28 is prevented from returning to vessel 26 by a backflow preventer 90. Here again, the nitrification operation takes place in the presence of biological support media 86 that circulates in vessel 28 under the influence of air from an aeration assembly 92 fed by the same blower 94 as the system of vessel 26, or by a separate blower. Here again, certain nitrification reactors may not require the addition of air (or oxygen), so that mixing may be performed by pulsed aeration or by a mixer. Moreover, as with vessel 26, other mixing and circulation mechanisms may be employed, such as pulsed air, mechanical mixers, and so forth.

[0035] In operation, wastewater is drawn from vessel 28 and may be advanced to a surge control vessel. As will be appreciated by those skilled in the art, where denitrification and nitrification are performed, recirculation will typically be performed from the nitrification vessel or a downstream surge vessel back to the recirculation flow line 76 illustrated in FIG. 9. Ultimately, some portion of the treated wastewater will flow from the secondary wastewater treatment system to downstream applications or further treatment.

[0036] As noted above, any one of the vessels illustrated in FIG. 9 may be replicated, although each vessel performs only a dedicated secondary wastewater treatment operation. It should also be noted that in the illustrated embodiment, the vessels are containerized but are up-ended such that the front of the container (see, FIGS. 5 and 6) becomes the bottom of each reactor vessel. The doors of the container may be removed, opened, or fully or partially closed. In a presently contemplated embodiment, the upper openings of each containerized reactor vessel are sufficiently distant from the open end of the container to permit the doors to be opened without interfering with or covering the openings. It should also be noted that in a typical application, a liquid level will be maintained in the vicinity of the upper openings, or slightly above or below the openings. This water level may vary in operation, depending upon the mass flow rates, residence times desired, volumes of the vessels, and so forth.

[0037] FIGS. 10 and 11 illustrate exemplary arrangements for partially or fully closing doors at the top of each containerized reactor vessel. As illustrated in FIG. 10, the container doors 64 are hinged to the sidewalls 34, but may be blocked partially opened by a block 96 to allow the exchange of gasses as indicated by reference numeral 98 into and out of the vessel, such as to accommodate aeration, liquid level changes, and so forth. Alternatively, as illustrated in FIG. 11, the doors may be completely closed, and ventilation may be provided by dedicated structures associated with the doors, such as with openings formed in the doors. For example, in the embodiment illustrated in FIG. 11, a ventilation blower unit 100 is provided for blowing outside air into the vessel, while a vent 102 is provided for allowing air to exit the vessel.

[0038] It should also be noted that certain vantages flow from the physical configuration of the containerized reactor vessels and their association with one another in the modular secondary wastewater treatment system. For example, because the vessels are constructed of standard intermodal containers, they may be easily assembled, modified, loaded and transported to the wastewater treatment location. From docks or ports, they can easily be trucked to an individual location, then up-ended and moved significantly closer to one another to form the group of vessels. The vessels may be held close to one another by any desired brackets, clamps and so forth, including corner fittings and locking bars commonly used to secure the containers on one another or on transport vehicles during transportation. The resulting structures present a significantly reduced footprint as compared to other wastewater treatment systems of similar throughput, and allow for complete modularization and scaling of any one or all of the individual operations performed in the dedicated reactor vessels. Finally, as will be appreciated by those skilled in the art, the secondary wastewater treatment operations described above may be referred to as biological nutrient removal (BNR), including denitrification, BOD, and nitrification. In some embodiments, however, BOD alone may be performed without nitrification or denitrification, depending upon the treatment desired, local regulations, and so forth. Moreover, other operations may be performed in the vessels, such as digestion (e.g., of sludge), sludge holding, biological phosphorous removal, and so forth. In specific applications, however, the systems may include only BOD (as noted above), only nitrification, only de-nitrification (e.g., downstream of an existing plant), BOD with de-nitrification (i.e., without nitrification), and so forth.

[0039] FIG. 12 illustrates an exemplary draft/mixing assembly for use in the system described above and illustrated in FIG. 9. As indicated above, the assembly may be used, for example, in a denitrification operation in which inlet flow 74 is to be mixed with recirculation flow 76 in a reactor vessel in which good mixing and circulation of biological support media is desired. In the embodiment illustrated in FIG. 12, a mixing tube 104 is provided that joins and inlet tube 106. The inlet tube may serve to receive the inlet flow 74. A further inlet tube 108 may serve to receive the recirculation flow 76, and extends into the mixing tube 104, while the first inlet tube 76 is joined to a sidewall of the mixing tube 104. The flows from the two inlet tubes join within the mixing tube, are mixed and flow out together through an open lower end 110. Once positioned in the reactor vessel, flow from the mixing tube will typically force liquid upwardly around the mixing tube. An open upper end 112 is positioned below the liquid level in the vessel, allowing circulation of fluid and biological support media into the mixing tube 104. The inflow through the tubes 104 and 106, then, promote the movement of fluid within the vessel, as well as the movement of biological support media. [0040] In a presently contemplated embodiment, the mixing tube 104 and inlet tube 106 and 108 are made of a plastic material, such as polyvinylchloride. However, other materials and construction details may also be employed. Moreover, by way of example only, in a presently contemplated embodiment, within a containerized reactor vessel approximately 8 ft. in width, a 3 inch inlet tube 106 joins a 6-8 inch mixing tube 104 in which a l¥z - 2 inch inlet tube 106 is inserted. The tubes may be joined to one another to form a unitary structure that is supported within the reactor vessel with the upper end 112 of the mixing tube below the surface of the wastewater being treated.

[0041] FIG. 13 illustrates exemplary steps in forming, transporting and installing the modular secondary wastewater treatment system described above. The process indicated generally by reference numeral 114 begins with adapting the container as indicated by step 116. Although the present invention is not limited to the use of any particular type of container, as noted above, in a presently contemplated embodiment and intermodal transport container, such as a standard 20 ft. container is adapted by forming sealed openings in at least one side wall, preferably at upper and lower locations, and closing these by appropriate seal covers. Internal structures may also be formed in the container, such as gussets, struts, reinforcement structures and so forth, as well as support structures, such as for receiving and supporting mixing tubes, aeration assemblies, and so forth.

[0042] As indicated by step 118, certain hardware may be assembled in the container prior to shipment. Step 118 is illustrated as optional because some or all of the hardware may be separately shipped and assembled later. However, where possible, certain of the components may be preassembled in the container before shipping. Moreover, due to the nature of the containerized vessels, certain system components may be supported in the container for shipping, thereby requiring little or no additional component shipping pallets or containers. Similarly, as indicated by optional step 120, biological support media may be preloaded into the vessels. In certain embodiments, the interior of the vessel may require access during set up of the system, and it will be desired to leave the media out of the vessel during shipping and set up, with the media being loaded separately after the vessels are situated at the treatment location.

[0043] At step 22, the vessels are shipped to the desired location, such as by traditional intermodal transport means (e.g., train, ship, truck). Once at the treatment location, the vessels are appropriately located, supported and stood on end. The vessels may be supported on platforms or foundations provided for this purpose, or may be placed on any suitable substrate. The vessels will typically be secured to one another and/or to surrounding structures to maintain in an upright and stable orientation during use. At steps 126 and 128, hardware may be assembled, as indicated at step 118 above, and biological support media may be loaded as indicated at step 120. These steps may include assembly of all hardware where the hardware has not pre-assembled, and loading of any additional media, or all media depending upon what loading has formerly taken place.

[0044] At step 130 flange covers are removed and interconnections are completed between the vessels so as to establish the desired series and/or parallel flow paths desired. For example, in the systems described above, series flow paths are established between the vessels performing different secondary wastewater treatment operations, whereas parallel paths may be established between vessels that perform identical operations (e.g., for scaling). At step 132 plumbing connections are complete as are other connections, such as to sensor, electrical connections for pump motor drives, and so forth. Finally, at step 134 the system may be filled and run, with each vessel performing its own dedicated treatment operation.

[0045] It should be noted that, while adaptation of prefabricated intermodal transport containers offers certain advantages for the present purposes, in certain embodiments it is also contemplated that non-standard or "made to order" vessels may be used that are not prefabricated for general purpose shipping. Such vessels may be made of any suitable material, or combinations of materials, such as synthetic plastics, metals, and so forth. However, to facilitate their transport to wastewater treatment locations, the vessels are fabricated to conform to ISO standard specifications for stacking and securement for intermodal transport, such as in overall dimensions, structural integrity sufficient to permit stacking, corner fittings to permit tie-in to other stacked containers, and so forth.

[0046] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

CLAIMS:

1. A modular wastewater treatment system comprising: a modular reactor configured to hold a biological support medium for a biological treatment process, the reactor defining a container conforming to intermodal freight transport container standards for stacking and securement, and having a bottom sealingly joined to an upwardly extending side wall to enclose an inner volume when the reactor is placed in an operational position, the wall having openings for the inflow and outflow of wastewater to be treated, wherein in the operational position the container has a height greater than any dimension of its footprint, and wherein the reactor is configured to be transported in a reclined orientation wherein it rests on the side wall.

2. The system of claim 1, wherein the reactor includes internal supports for an aeration assembly.

3. The system of claim 1, wherein the side wall has four generally rectangular wall sections, and wherein the openings are formed in only one of the wall sections.

4. The system of claim 1, wherein the reactor has an open end opposite the bottom and closed by a door during transport of the reactor.

5. The system of claim 4, wherein the door is ventilated for permitting the inflow or outflow of gas during operation of the reactor.

6. The system of claim 1, comprising a plurality of modular reactors each conforming to intermodal freight transport container standards, each reactor being joined to an adjacent reactor by a conduit extending from an opening of a first reactor to an opening of a second reactor.

7. The system of claim 6, wherein the reactors are configured to perform nitrification and denitrification operations.

8. The system of claim 1, wherein the reactor has at least one opening in a lower position and at least one opening in an upper position, whereby the reactor can be joined to another modular reactor by one or more conduits extending between openings of both reactors.

9. The system of claim 1, comprising two self-similar reactors joined to one another in a matrix, wastewater flowing from one reactor to another to perform secondary wastewater treatment.

10. The system of claim 9, wherein the reactors are joined to one another in at least two rows, and wherein a walkway is disposed above the reactors and between the rows.

11. A modular wastewater treatment system comprising: a plurality of modular reactors configured to hold a biological support medium for a biological treatment process, the reactors conforming to intermodal freight transport container standards for stacking and securement, and having a bottom sealingly joined to an upwardly extending side wall to enclose an inner volume when the reactor is placed in an operational position, the wall having openings for the inflow and outflow of wastewater to be treated, wherein in the operational position the container has a height greater than any dimension of its footprint, and wherein the reactor is configured to be transported in a reclined orientation wherein it rests on the side wall; the reactors each performing one secondary wastewater treatment operation in its respective inner volume, the reactors being joined to one another such that wastewater flows from one reactor to the next in series via the openings in each reactor.

12. The system of claim 11, wherein a first reactor is configured to receive wastewater and to perform a denitrification process, the wastewater being transferred from an opening of the first reactor to an opening of a second reactor.

13. The system of claim 12, wherein the second reactor is configured to receive the wastewater and to perform a biochemical oxygen demand reduction process, the wastewater being transferred from an opening of the second reactor to an opening of a third reactor.

14. The system of claim 13, wherein the third reactor is configured to receive the wastewater and to perform a nitrification process, a portion of the wastewater from the third reactor being recirculated to the first reactor.

15. The system of claim 11, wherein at least two of the reactors perform identical secondary wastewater treatment operations.

16. The system of claim 11, wherein each reactor has an open end opposite the bottom and closed by a door during transport of the reactor.

17. The system of claim 16, wherein the door of at least one of the reactors is ventilated for permitting the inflow or outflow of gas during operation of the reactor.

18. A modular wastewater treatment system comprising: a plurality of modular reactors configured to hold a biological support medium for a biological treatment process, the reactors conforming to intermodal freight transport container standards for stacking and securement, and having a bottom sealingly joined to an upwardly extending side wall to enclose an inner volume when the reactor is placed in an operational position, the wall having openings for the inflow and outflow of wastewater to be treated, wherein in the operational position the container has a height greater than any dimension of its footprint, and wherein the reactor is configured to be transported in a reclined orientation wherein it rests on the side wall; a first reactor being configured to receive wastewater and to perform a denitrification process, the wastewater being transferred from a lower opening of the first reactor to an upper opening of a second reactor; the second reactor being configured to receive the wastewater and to perform a biochemical oxygen demand reduction process, the wastewater being transferred from a lower opening of the second reactor to an upper opening of a third reactor; and the third reactor is configured to receive the wastewater and to perform a nitrification process, a portion of the wastewater from the third reactor being recirculated to the first reactor.

20. The system of claim 19, comprising at least two first, second or third reactors performing identical secondary wastewater treatment operations.

21. A method for wastewater treatment comprising: in an intermodal freight transport container having a front wall sealingly joined to four side walls and an open end opposite the front wall, forming openings in at least one side wall, the openings being spaced from one another in upper and lower positions when the container is placed on the front wall to form a generally vertical wastewater treatment reactor with a wastewater level between the upper and lower positions.

22. The method of claim 21, comprising disposing supports in the container for an aeration assembly.

23. The method of claim 21, wherein the openings are flanged openings.

24. The method of claim 21, comprising sealingly securing a blank cover to each of the flanged openings.

25. The method of claim 21, wherein the container comprises doors over the open end, and wherein the method comprises disposing a vent in at least one of the doors to permit inflow or outflow of gas during operation of the reactor.

26. The method of claim 21, comprising shipping the container to a wastewater treatment location, placing the container in a generally vertical orientation with the front wall downward, and coupling a wastewater flow conduits to at least one of the openings.

27. The method of claim 21, comprising shipping multiple self similar containers to the wastewater treatment location, placing each container in a vertical orientation with the front wall downward, and coupling wastewater flow conduits between openings of the containers.

28. The method of claim 27, wherein each container forms a reactor and performs only one secondary wastewater treatment operation.

29. The method of claim 28, comprising partially filling at least one of the containers with a biological support medium.

30. The method of claim 28, comprising disposing an aeration assembly in the at least one container to bubble air around the biological support medium.

31. A method for wastewater treatment comprising: forming a plurality of reactors, each reactor being formed by, in an intermodal freight transport container having a front wall sealingly joined to four side walls and an open end opposite the front wall, forming openings in at least one side wall, the openings being spaced from one another in upper and lower positions when the container is placed on the front wall to form a generally vertical wastewater treatment reactor with a wastewater level between the upper and lower positions; shipping the reactors to a wastewater treatment location by standard intermodal freight transport container shipping transport; placing the reactors in a generally vertical orientation with the front wall downward; coupling a wastewater flow conduits conduits between openings of the containers, each reactor performing only one secondary wastewater treatment operation.

32. The system of claim 31, wherein the reactors perform at least a biochemical oxygen demand reduction operation.

33. The system of claim 31, wherein at least two reactors perform identical secondary wastewater treatment operations.

34. The system of claim 31, wherein a first reactor is configured to receive wastewater and to perform a denitrification process, the wastewater being transferred from a lower opening of the first reactor to an upper opening of a second reactor.

35. The system of claim 34, wherein the second reactor is configured to receive the wastewater and to perform a biochemical oxygen demand reduction process, the wastewater being transferred from a lower opening of the second reactor to an upper opening of a third reactor.

36. The system of claim 35, wherein the third reactor is configured to receive the wastewater and to perform a nitrification process, a portion of the wastewater from the third reactor being recirculated to the first reactor.

37. A method for wastewater treatment comprising: in an intermodal freight transport container having a front wall sealingly joined to four side walls and an open end opposite the front wall, forming openings in at least one side wall, the openings being spaced from one another in upper and lower positions when the container is placed on the front wall to form a generally vertical wastewater treatment reactor with a wastewater level between the upper and lower positions; and securing sealed flanged connections in each of the openings for receiving complementary flanged wastewater flow conduits when the reactor is placed in service.

39. The method of claim 37, comprising disposing supports in the container for an aeration assembly.

40. The method of claim 37, wherein the container comprises doors over the open end, and wherein the method comprises disposing a vent in at least one of the doors to permit inflow or outflow of gas during operation of the reactor.

41. A wastewaster treatment system comprising: a reactor vessel configured to receive a wastewater feed stream and recirculated wastewater from a downstream process; and a draft tube mixer disposed at least partially in the reactor vessel and including an outer mixing tube, a first inlet tube joining a side wall of the outer mixing tube for communicating a first flow from the first inlet tube to an interior of the outer mixing tube, and a second inlet tube extending through an open upper end of the outer mixing tube for communicating a second flow from the second inlet tube to the interior of the outer mixing tube, the first and second flows mixing in the mixing tube.

42. The system of claim 41, wherein the first flow is a wastewater feed stream, and the second flow is recirculated waste water.

43. The system of claim 41, wherein the reactor vessel is configured to perform a denitrification process, and wherein the recirculated wastewater is communicated to the reactor vessel from a second reactor vessel that performs a nitrification process.

44. The system of claim 41, wherein the mixing tube has an open upper end disposed below a level of wastewater in the reactor vessel.

45. The system of claim 44, wherein the reactor vessel contains biological growth support media, and wherein the biological growth support media freely enters the open upper end of the mixing tube and freely exits an open lower end thereof along with the mixed first and second flows.