WO2010025275A1

WO2010025275A1 - Integrated wastewater treatment system and method

Info

Publication number: WO2010025275A1
Application number: PCT/US2009/055224
Authority: WO
Inventors: Jack Collie Gardiner; Gerald Seidl
Original assignee: Headworks Bio Inc.
Priority date: 2008-08-27
Filing date: 2009-08-27
Publication date: 2010-03-04

Abstract

An integrated wastewater treatment system is provided that significantly reduces the footprint as compared to conventional systems. Components for primary wastewater treatment are mechanical in nature and provide for initial screen filtration, such as for the removal of trash and particulates down to a first size. This screen filtration is fully integrated with fine filtration to complete the primary wastewater treatment. The primary wastewater treatment is integrated with the secondary wastewater treatment, which may be positioned immediately adjacent to or below the primary wastewater treatment components to allow for flow directly from one to the other, further reducing the footprint and increasing efficiency and throughput.

Description

INTEGRATED WASTEWATER TREATMENT SYSTEM AND

METHOD

BACKGROUND

[0001] The present invention relates generally to wastewater treatment. More particularly, the invention relates to new techniques for integration of primary and secondary wastewater treatment that significantly reduce the footprint for systems, increasing their utility, applicability, affordability and efficiency.

[0002] A number of systems and techniques have been designed and are in service for wastewater treatment. In general, such systems may receive residential, commercial, and/or industrial wastewater, as well as run-off or storm sewage, at least from time to time. The techniques commonly in use for such systems may be classified as primary treatment, secondary treatment and tertiary treatment. Primary treatment facilities often include large facilities in which wastewater is permitted to sit or circulate. The primary treatment often depends upon settling of solids from the wastewater until a desired level of solids content is obtained. Such systems may not only require and occupy large amounts of real estate, but in many cases may not actually be able to obtain the reduced level of solids desired. Many localities, industries, commercial installations, residential areas, and the like simply cannot afford the large land areas required for such conventional primary treatment. Similarly, secondary treatment may include processes that may not consistently obtain the desired level of solids and biological material reduction.

[0003] There is an increasing need for improved wastewater treatment systems that can significantly reduce the footprint of the overall system, while providing a high level of solids and biological material removal. There is a particular need for systems that can integrate various primary treatment approaches, and secondary treatment approaches, and eventually tertiary treatment. Current systems provide little or no overall integration in a "packaged" design. Accordingly, most often components that more or less serve purposes in conjunction with one another are cobbled together into a overall system with increased cost, reduced efficiency, and increased maintenance needs. In some cases, municipalities or operators must contact disparate suppliers to trace spare parts, address system trouble-shooting, and maintain the equipment in reliable working order.

BRIEF DESCRIPTION

[0004] The present invention provides an integrated wastewater treatment approach that is designed to satisfy certain of these needs. In particular, the approach provides mechanical primary treatment that integrates a coarse screening system with a fine filtering system. These two may be partially or completely integrated with one another, and may include common drives, common trash or sludge removal, and so forth. The primary treatment may also include grit separation, where desired.

[0005] The primary treatment is further integrated with secondary or biological treatment. In particular, in accordance with certain embodiments, wastewater from the primary treatment flows directly into the secondary treatment. The secondary treatment may include one or redundant reactors in which biological treatment is performed. The secondary treatment may also include dissolved air floatation or sieve removal of contaminants, such as clarifiers, filters, and so forth. Finally, where desired, these primary and secondary treatment approaches may be incorporated with tertiary approaches, such as fine filtering for effluent polishing.

DRAWINGS

[0006] 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:

[0007] FIG. 1 is a diagrammatical overview of a wastewater treatment system incorporating integrated primary treatment, and also integrating primary treatment with secondary treatment;

[0008] FIG. 2 is a diagrammatical representation of integrated primary or mechanical wastewater treatment of FIG. 1; [0009] FIG. 3 is a diagrammatical representation of an alternative integrated primary treatment arrangement for higher through-put;

[0010] FIG. 4 is diagrammatical representation of an exemplary installation for integrated primary and secondary wastewater treatment;

[0011] FIG. 5 is a further diagrammatical representation of the integrated primary and secondary wastewater treatment system;

[0012] FIG. 6 is a similar diagrammatical representation of an integrated primary and secondary wastewater treatment system, but in which a clarifier is used and in which sludge is recirculated to the primary treatment screening system;

[0013] FIG. 7 is an elevational view of an exemplary installation for primary and secondary wastewater treatment in accordance with FIGS. 4 and 5;

[0014] FIG. 8 is a plan view of the exemplary installation of FIG. 7; and

[0015] FIG. 9 is a detailed elevation of a portion of the system of FIGS. 7 and 8 illustrating the integrated primary or mechanical treatment components.

DETAILED DESCRIPTION

[0016] Turning now to the drawings, and referring first to FIG. 1, a wastewater treatment system 10 is illustrated diagrammatically. The system is designed to receive wastewater 12 and to output treated wastewater 14. The illustrated system includes primary treatment 16, described in greater detail below, secondary treatment 18 and tertiary treatment 20. As described further below, components of the primary treatment 16 may be mechanical in nature, significantly reducing the footprint of the primary treatment as compared to existing settling-type installations. Moreover, components of the primary treatment may be integrated with one another to provide enhanced operability and efficiency, and further reducing maintenance costs. Similarly, the primary treatment may be partially or fully integrated with the secondary treatment as described below. In certain applications, primary treatment alone will be sufficient to meet the needs of the particular application. In other situations, the primary and secondary treatment, together, would be sufficient to meet the application requirements. In still other applications, however, tertiary treatment will be desired, and for such cases, all three levels of treatment may be cascaded as illustrated in FIG. 1.

[0017] In the illustrated embodiment, the wastewater 12 is introduced to the primary treatment 16 through an initial screen filter 22. Various types of screen filtering of this type are known and commercially available. For example, various types of bar or screen filter may be used for filter 22, such as those described in U.S. Patents 6,666,977; 6,719,912; 7,147,784; and 7,220,361, all assigned to Headworks, Inc. of Houston, Texas, and hereby incorporated in their entirety into the present description. It should be noted that while a screen filter is illustrated in FIG. 1, such filtering may in general be known by different names, such as, for example, equipment available from the Headworks, Inc., under the commercial designations Mahr bar screens, Eliminator band, Perforator screens, X-tractor, Spiralman, Black Box, and so forth. In general, such systems receive wastewater and remove large trash and solid particles from the wastewater, performing a coarse filtering operation. The screen filtering 22 may reduce solids in the wastewater to approximately 1-4 mm, for example. The resulting trash or sludge formed by the removed contaminants is carried away, such as by a screw auger for disposal as indicated in FIG. 1.

[0018] Wastewater from the initial screen filtering flows directly into the fine filtering as indicated at reference numeral 24. Such fine filtering may be performed by mechanical means, such as cylinder-type systems or through systems described in U.S. Patent No. 6,942,786, assigned to Salsnes of Norway, the entirety of which is incorporated into the present description by reference. More generally, such fine filtering may be performed by drum screens, microfilters, and so forth, available from a range of sources. Such systems may operate by circulating a mat or belt of a woven or non-woven material through wastewater flowing downstream of the initial screening filter. The mat collects very fine particulate matter and suspended solids, allowing wastewater with smaller entrained solids to flow through the filter. The solids and particulate matter collected by the mat may then be removed, such as by impacting the mat with a stream of air and/or water, to form a sludge that is carried away for disposal as indicated in FIG. 1. Such filtration may be carried on to a level of particulate solids in the wastewater as fine as 50-100 microns. Moreover, as with the initial screen filtering, the fine filtering may be designed to increase or slow the speed of screens and belts based upon a differential pressure across the screens and belts, thereby maintaining a relatively constant pressure differential forcing flow through the device.

[0019] Filtered wastewater from the primary mechanical treatment flows to the secondary treatment 18. In the illustrated embodiment, the secondary treatment includes one or more bio-media reactors 26. These reactors further filter the wastewater by means of bacteria or other biological materials that may be supported on molded plastic or other media. In the presently contemplated embodiment, for example, the reactors have a freely circulating support media suspended within the wastewater, with bacterial growths on the media that aid in removal of contaminants from the wastewater. Moreover, in the illustrated embodiment redundant bio-media reactors are provided as indicated by reference numerals 26 and 28, both increasing the normal throughput of the system and providing for continued operation in the event of operational problems or servicing of either one of the reactors. In certain applications as few as a single reactor may be provided, or more than two reactors could be provided where desired. In a presently contemplated embodiment, the bio- media reactors may be of the type offered commercially by Headworks Bio Inc. of Houston, Texas or BioWater Technology of Tønsberg, Norway. From the bio-media reactors, the wastewater flows to a dissolved air floatation system as indicated by reference numeral 30. In certain applications, however, the dissolved air floatation system may be replaced with a clarifier or other filter to complete the secondary treatment process. In a presently contemplated embodiment, the dissolved air floatation system 30 may be of a type available commercially from Headworks Bio Inc.

[0020] Once the secondary treatment is completed, the wastewater may flow to the tertiary treatment, where provided. In the illustrated embodiment, the tertiary treatment may include effluent polishing as indicated by reference numeral 32. As will be appreciated by those skilled in the art, such polishing may be accomplished in various means, typically by fine filtration, such as by percolation through sand or other media.

[0021] FIG. 2 illustrates a presently contemplated integrated primary treatment arrangement 16. As discussed above, the primary treatment arrangement may include initial screen filtering 22 followed by fine filtering 24. Trash or sludge from both processes may be extracted for disposal. In the embodiment of FIG. 2, however, an optional grit separation component 34 is included. Such grit separation may include movement of the wastewater through stones, pebbles, or other media, such as for the settling or removal of sand and other debris. Similarly, FIG. 3 illustrates a further alternative for the integrated primary treatment. In this embodiment, the initial screen filtering 22 has a larger capacity than the fine filtering stage as indicated by reference numeral 36. Thus, the outflow from the initial screen filtering is divided or manifolded for fine filtration. The grit separation component 34 is illustrated as optional in this embodiment, and if provided is disposed between the initial screen filtering and the fine filtration.

[0022] FIG. 4 illustrates a somewhat detailed view of the integrated primary and secondary wastewater treatment arrangements discussed above. As again indicated by reference numeral 16, the primary wastewater treatment begins with wastewater 12 being introduced into the initial screen filtering 22. A level of wastewater as indicated by reference numeral 40 will develop due to back pressure offered by the screen 38 which circulates within the vessel. Following passage of the wastewater through the screen, a lower water level 42 will be present, which will flow from the screen filtering to the fine filtering stage. A circulating drum cylinder, mat or web 44 then removes finer solids from the wastewater, resulting in a lower water level 46 downstream of the fine filtering. This wastewater is permitted to feed or drain, or may be pumped into the reactors for secondary wastewater treatment. As will be appreciated by those skilled in the art, by integration of the initial screen filtering and the fine filtering, similar or the same controls may be used for both, and wastewater may be permitted to flow steadily between the inlet and outlet of the primary wastewater treatment arrangement. Moreover, trash and sludge removal may be integrated. A significant advantage of such integration of both screen and fine filtering in the primary wastewater treatment stage is the reduction in the overall footprint as compared to conventional wastewater treatment systems of the same flow rate.

[0023] The secondary wastewater treatment arrangement illustrated in FIG. 4 includes parallel bio-media reactors 26 and 28. In each of the reactors, media 48 are freely suspended in the wastewater, which is allowed to rise to a level indicated by reference numeral 50 in FIG. 4. As noted above, this media may include supports for bacteria or other biological organisms which aid in removal of additional contaminants from the wastewater. The media is maintained in suspension or may move within the wastewater, thereby contacting the wastewater increasingly as residence time increases and as the wastewater flows through the reactor. From reactors 26 and 28, the wastewater flows into downstream reactors 52 and 54, respectively. These reactors may include similar media and further clarify the wastewater being processed. The flow of wastewater between reactors 26 and 52, and 28 and 54 is generally facilitated by apertures, openings or filters as indicated at reference numerals 56 and 58, respectively. At the same time, aeration conduits 60 provide for the injection of air into the reactors both to maintain movement of the media and to provide necessary oxygen for sustenance of the biological growth on the media. Again, wastewater is then collected from the downstream reactors 52 and 54 and transmitted to the dissolved air floatation unit 30.

[0024] FIG. 5 is a flow diagram of an exemplary integrated arrangement of this type. Again, the wastewater is first collected in a lift station 62 from which it is drawn for primary screening as indicated by reference numeral 64. The screening results in the extraction of trash and sludge which may be conveyed to a trash or sludge collector 66. Degritting may be performed in a station 68 in a similar manner, with removed sludge being conveyed to the collector 66. Primary treatment screening and filtering may then be performed by the techniques described above, for removal of first larger solids, then finer solids in a single integrated unit. The sludge resulting from the primary wastewater treatment stage may then be conveyed to a sludge holding tank as indicated at reference numeral 70. As will be appreciated by those skilled in the art, the sludge may be further dried or dewatered, as desired, after which it may be removed to a landfill or processed for other purposes.

[0025] As noted above, the wastewater then flows into one or more reactors which may be provided in a redundant fashion, and in series as illustrated in FIG. 5. Thus, in a presently contemplated embodiment the wastewater flows into a first reactor 26, 28, in which biological growth support media 48 circulates. Air for supporting the biological growth is provided by an aeration system. The wastewater is then allowed to flow through a secondary reactor 52, 54 for further waste removal. Ultimately, then, the wastewater flows through the dissolved air floatation unit 30 or through a clarifier or other filter. Finally, in the embodiment illustrated in FIG. 5, the wastewater may flow through a disinfecting treatment unit 72, such as an ionic, chemical, ultraviolet (UV) and/or ozone disinfecting system, before being discharged. The discharge may occur directly downstream of the secondary treatment stage, or the discharge may be forwarded to further tertiary wastewater treatment. Whether the system employs primary treatment alone, primary treatment in conjunction with secondary treatment, or primary, secondary and tertiary treatment typically depends upon the level of clarity and water quality desired, and upon local wastewater treatment regulations.

[0026] FIG. 6 is a flow diagram similar to that of FIG. 5, but in which the dissolved air flotation unit 30 has been replaced with a clarifier 30'. Such arrangements may operate best by drawing off the sludge from the clarifier for thickening. In the arrangement illustrated in FIG. 6, therefore, the waste activated sludge from the clarifier may be drawn off and recirculated to the primary treatment equipment. In the illustrated embodiment, the secondary sludge from the clarifier is reintroduced and combined with the wastewater flow into the fine filter 24. The filter will effectively mix the recirculated sludge with the finer solids that are removed and conveyed to the sludge holding tank 70. It is thought that the finer solids may have sufficient fibrous material to bind the secondary sludge, and that the combined sludge may have a solids content of 4-6 %. Moreover, rather than transferring the combined sludge to a sludge holding tank, it may be transferred to an anaerobic digester for gas and energy recovery. Alternatively, the combined sludge may be sent to an aerobic digester for stabilization and subsequent distribution, such as for land applications (e.g., fertilizers, etc.).

[0027] FIGS. 7 and 8 illustrate an exemplary arrangement presently contemplated that implements the reduced footprint, integrated approach described above. As illustrated in FIGS. 5 and 6, the arrangement makes use of a series of first reactors 26 and 28 followed by respective secondary reactors 52 and 54. As best illustrated in the plan view of FIG. 8, primary wastewater treatment may be performed by equipment disposed above the reactors, including screening separation followed by fine filtration, as indicated by reference numerals 22 and 24. Wastewater from the fine filtration, in this case the downstream unit in the primary wastewater treatment, flows directly into reactors 26 and 28. Blowers 74, which also may be disposed above the reactors, provide for aeration of the reactors by appropriate piping as indicated at reference numeral 60 in FIG. 7. Air is thus forced into the wastewater collecting in the reactors and bubbles up to cause movement and circulation of the wastewater and biological support media (not shown in FIGS. 7 and 8), and to support the biological growth on the media.

[0028] Wastewater is allowed to flow from the initial reactors 26 and 28, which are separated by a partition 76, into the secondary reactors 52 and 54 through screens. In the case of the initial reactor 26, a screen 80 is provided in a partitioning wall 78. The wastewater may freely flow into the secondary reactor and ultimately exits the reactor through a similar screen 82. In a similar manner, wastewater from initial reactor 28 flows through a screen 88 in a partition 86 between this initial reactor and secondary reactor 54. From there, wastewater is further purified and can flow out through a screen 90. The outflow from the secondary reactors is collected by piping 84 which joins piping 92 flowing from reactor 54. This piping may unite the effluent flows and channel flow to the dissolved air floatation unit 30, or to a clarifier, or further filter for further secondary wastewater treatment. It should be noted that valving (not shown) may be provided at various locations in these insulations, such as to allow for interrupting flow into any one of the reactors, and/or flow from any one of the reactors. In this way, either the initial reactors or secondary reactors may be taken out of service for maintenance reasons, equipment servicing, and the like without interrupting operation of the overall system.

[0029] As will be appreciated by those skilled in the art, the installation illustrated in FIGS. 7 and 8 have a significantly reduced footprint as compared to conventional systems with similar wastewater treatment flow capabilities. This results from integration both of the components of the primary wastewater treatment and the secondary wastewater treatment, as well as from the further integration of the primary and secondary wastewater treatment components with one another. In certain configurations, the footprint of the wastewater treatment system 10 may be further reduced by providing first reactors 26 and 28, and secondary reactors 52 and 54 with decreased cross-sectional areas compared to conventional systems having similar reactor volume. As will be appreciated, decreasing the cross-sectional area while maintaining the volume establishes reactors having a greater height. The greater reactor height may facilitate increased oxygen transfer efficiency. Specifically, a fraction of the air entering the reactors through the conduits 60 is absorbed by the wastewater as the air bubbles through the reactors. Consequently, greater reactor height may increase the quantity of oxygen transferred to the wastewater. The increased oxygen transfer efficiency may enable the blowers 74 to provide a decreased flow of air while maintaining a desired wastewater oxygen content, thereby decreasing power consumption of the wastewater treatment system 10.

[0030] FIG. 9 is a more detailed representation of a presently contemplated arrangement for the primary wastewater treatment in the installation shown in FIGS. 7 and 8. In particular, the coarse or screen filtration 22 is integrated with the fine filtration 24 such that wastewater continuously flows from the inlet through the various stages of filtration to be released into the bio-media reactors. As indicated above, an auger or other trash and sludge removal equipment 64 removes the trash and sludge that collects in the screen and fine filtering systems. [0031] While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

Claims

CLAIMS:

1. An integrated wastewater treatment system comprising: a mechanical primary treatment system configured to perform initial screening of a wastewater stream; and a secondary biological treatment system configured to receive the screened wastewater stream from the primary treatment system and to perform at least one biological reaction to treat the wastewater stream; wherein the mechanical primary treatment system is at least partially disposed above the secondary biological treatment system.

2. The system of claim 1, wherein the mechanical primary treatment system includes an initial screen filter and a fine filter downstream of the screen filter.

3. The system of claim 2, wherein the mechanical primary treatment system includes a plurality of fine filters downstream of the screen filter.

4. The system of claim 1, wherein the secondary biological treatment system includes at least one reactor in which a biological growth support media is disposed, biological growth on the media promoting treatment of the wastewater stream during operation.

5. The system of claim 4, wherein the secondary biological treatment system includes a plurality of redundant reactors performing similar treatment operations.

6. The system of claim 4, comprising an air injection conduit for injecting oxygen into the wastewater stream for sustenance of the biological growth.

7. The system of claim 1, comprising a dissolved air flotation system downstream of the secondary biological treatment system and configured to receive the treated wastewater stream from the secondary biological treatment system.

8. The system of claim 1, comprising a clarifier downstream of the secondary biological treatment system and configured to receive the treated wastewater stream from the secondary biological treatment system.

9. The system of claim 8, wherein wastewater activated sludge from the clarifier is circulated to the mechanical primary treatment system and combined with the wastewater stream.

10. The system of claim 9, wherein sludge removed from the wastewater stream by the mechanical primary treatment system is combined with the wastewater activated sludge and the combined sludge is conveyed to a sludge holding tank.

11. The system of claim 10, wherein the combined sludge has a solids content of between 4 and 6 %.

12. An integrated wastewater treatment system comprising: a mechanical primary treatment system configured to perform initial screening of a wastewater stream; a secondary biological treatment system configured to receive the screened wastewater stream from the primary treatment system and to perform at least one biological reaction to treat the wastewater stream; and a clarifier downstream of the secondary biological treatment system and configured to receive the treated wastewater stream from the secondary biological treatment system, wherein wastewater activated sludge from the clarifier is circulated to the mechanical primary treatment system and combined with the wastewater stream.

13. The system of claim 12, wherein the mechanical primary treatment system is at least partially disposed above the secondary biological treatment system.

14. The system of claim 12, wherein the mechanical primary treatment system includes an initial screen filter and a fine filter downstream of the screen filter.

15. The system of claim 14, wherein the secondary biological treatment system includes at least one reactor in which a biological growth support media is disposed, biological growth on the media promoting treatment of the wastewater stream during operation.

16. The system of claim 15, wherein the secondary biological treatment system includes a plurality of redundant reactors performing similar treatment operations.

17. The system of claim 15, comprising an air injection conduit for injecting oxygen into the wastewater stream for sustenance of the biological growth.

18. An integrated wastewater treatment system comprising: a mechanical primary treatment system including an initial screen filter and a fine filter downstream of the screen filter configured to perform initial screening of a wastewater stream; a secondary biological treatment system at least partially disposed above the secondary biological treatment system and configured to receive the screened wastewater stream from the primary treatment system and to perform at least one biological reaction to treat the wastewater stream; and a clarifier downstream of the secondary biological treatment system and configured to receive the treated wastewater stream from the secondary biological treatment system, wherein wastewater activated sludge from the clarifier is circulated to the mechanical primary treatment system and combined with the wastewater stream.

19. The system of claim 18, comprising a dissolved air flotation system downstream of the secondary biological treatment system and configured to receive the treated wastewater stream from the secondary biological treatment system.

20. The system of claim 18, wherein sludge removed from the wastewater stream by the mechanical primary treatment system is combined with the wastewater activated sludge and the combined sludge is conveyed to a sludge holding tank.