Patent Application
20200009480
This invention relates to a system and method for selectively harvesting and optionally treating water for withdrawal from a storage reservoir or the like.
Any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material forms part of the prior art base or common general knowledge in the relevant art in Australia or elsewhere on or before the priority date of the disclosure and claims herein.
Water quality and characteristics within a surface water source (e.g. reservoir, lake, lagoon, catchment, etc.) can vary significantly as a function of depth and/or location within the water body. Cool, dense water at lower depths may contain high concentrations of metals, hydrogen sulfide, nutrients, and biomass from decaying organic matter. Warm, sunlit layers near the surface can experience wide swings in water characteristics due to photosynthesis and the algae respiration cycle. Water acidity may even vary across the course of a day, for example from pH 6.5 early in the morning to pH 8.5 late in the afternoon. Seasonally, a reservoir can experience “turnover” events where bottom layers of water reverse positions with those that were closer to the surface. Water at the surface can have negligible manganese levels on one day, for example, then after turnover it can dramatically increase. Although water characteristics in a given layer of water can remain constant during certain periods of the year, and be consistent throughout a reservoir, in some circumstances they can be expected to change at least seasonally and sometimes weekly, daily, or even hourly.
Reservoir water temperature and other characteristics are important because they may impact upon downstream processes that utilize water from the reservoir. Utilities, for example, will treat raw water with various chemicals and processes in order to make it suitable as public drinking water. Power plants are another example where not only does the water source require treatment, but the temperature of the water can impact power production.
The withdrawal of water out of a reservoir is accomplished through and only adjacent to an intake structure. A typical intake structure has one or more gates or withdrawal points at fixed elevations within the water body (
Although drawing water from an uppermost gate is usually the preferred approach to extracting water from a reservoir, it can present some challenges. Since water near the surface may contain algae, and algae goes through a respiration cycle each day, water near the surface can have widely varying pH and dissolved oxygen levels. This can be problematic for chemical dosing schemes and treatment processes, and significantly add to the overall cost of treatment. Algae can contribute greatly to taste and odor excursions, particularly when certain bacteria die and Methyl-Isoborneol (MIB) and Geosmin are released into the water. There may be no greater cost of treatment than that associated with removing taste and odor compounds from public drinking water.
In view of the foregoing, the inventor has realised that it would be desirable to enable water withdrawal from a reservoir from a selected water depth and/or from one or more selected locations within or in the vicinity of the water body in order to obtain particular water characteristics in the withdrawn water. Moreover, the inventor has recognised that there may be beneficial outcomes that can be achieved if a system for dynamically selecting water for withdrawal can be retrofitted to intake structures of existing reservoirs.
In accordance with the present invention there is provided a system for use with a water storage facility having a water body and an extraction structure, the system comprising a water selection apparatus interposed between the water body and the extraction structure, the water selection apparatus having a controllable inlet that allows water from a selectable depth within the water body to be harvested for withdrawal through the extraction structure.
In accordance with the present invention there is also provided a system for use with a water storage facility having a water body and an extractions structure, the system comprising a water selection and relocation apparatus installed within or in the near vicinity of the water body having a controllable inlet that allows water from a selectable location remote from the extraction structure to be relocated directly to the extraction structure for withdrawal through the extraction structure.
A barrier structure may be provided forming a partitioned volume enclosing or attached to the extraction structure wherein the water selection apparatus controls water flow from the water body to the partitioned volume.
The water selection apparatus may comprise a selector interface integrated with the barrier structure and including a plurality of selector gates positioned at respective depths in the water body, the gates being selectively operable to admit water from the corresponding depth to the partitioned volume. Alternatively, the water selection apparatus may comprise a fluid conduit such as a pipe having an inlet that is moveable to a selected depth within the water body and an outlet in the partitioned volume.
A monitoring apparatus may be provided, arranged for measuring and monitoring at least one water quality characteristic over at a plurality of depths within the water body, wherein the water selection apparatus is controlled according to detected differences in the at least one water quality characteristic as between different depths.
In accordance with another aspect of the present invention, there is provided a method for controlling the quality of water for withdrawal from a water body by way of an extraction structure, the method comprising selectively harvesting water from a dynamically controllable depth within the water body before admitting the harvested water for withdrawal through the extraction structure.
The method may include monitoring at least one water quality characteristic over at a plurality of depths within the water body and controlling the depth at which water is harvested according to detected differences in the at least one water quality characteristic as between different depths.
The method may include retaining the harvested water in a partitioned volume of the water body before withdrawal through the extraction structure. At least one water treatment steps or processes may be applied to the water in the partitioned volume prior to withdrawal through the extraction structure.
The method and apparatus according to embodiments of the invention allows for the dynamic withdrawal and/or harvesting of water within a water body at depths corresponding to not only those established by the withdrawal structure's fixed-elevation extraction points (e.g. gates, valves, weirs, etc.), but also additional depths above, below, or between the fixed-elevation extraction points. This may allow water to be harvested at continuous depths, or any depth, or multiple depths.
Embodiments of the invention allow water at a select depth or depths to be separated and isolated within the water body. Water at variable depths can be dynamically separated and isolated based on water quality criteria and/or characteristics, and potentially changing criteria. This may facilitate treatment and/or conditioning of the separated and isolated water prior to being extracted through a harvesting structure having fixed-elevation extraction point(s). Treatments may include aeration, oxidation, coagulation, adsorption, absorption, flotation, skimming, heating, cooling, disinfection or other forms of physical/chemical/thermal treatment of the separated and isolated water. Multiple stages of treatment and/or separate zones of treatment may be employed.
Embodiments of the invention provide for monitoring water quality and characteristics as a function of depth within the water body.
In embodiments of the invention a barrier may be installed within the body of water to isolate water of varying quality and characteristics. The barrier may be rigid as in construction from concrete, metal, or earth. Alternatively the barrier may be flexible in the form of a baffle curtain or the like. Pressure relief mechanisms may be incorporated within the barrier structure to ensure the structural integrity of the water quality barrier is not compromised.
The barrier structure may be vertical in the water column, or angled. The barrier may be collapsible/expandable/flexible with changing water level in the body of water. The barrier may preferably be of a dimensional size and volume to create sufficient detention/residence time for the selected water to undergo treatment based on the maximum harvesting rate of the water. For example, the barrier may be of dimensional size and volume to create a minimum of five minutes of residence time for the harvested water before it is withdrawn.
The apparatus used to separate water within the water body is preferably designed with sufficiently minimal head-loss so as to not compromise the structural integrity of the water quality barrier. With that in mind, the system may be designed in a way that at least some portion of the apparatus is always open to allow for the transmission of water across the apparatus.
The water selection apparatus may utilize one or more orifices—gates, windows, or openings—for permitting water flow from one side of the barrier to the other. The gates or windows within the apparatus may be dynamically opened or closed through manual, pneumatic, mechanical, hydraulic, electric, or mechanical means. The gates preferably minimize or eliminate the transmission of water when closed, but may open in the event pressure relief is needed across the barrier.
In another form the water selection apparatus may utilize one or more pipes or conduits that are fixed to the water quality barrier. partitioned volume or extraction structure on one end, and raised and lowered on the other end to allow for the transmission of water at select depth(s) to be drawn into the partitioned volume defined by the barrier or directly into the extraction structure. The pipes may be constructed of various different types of material, such as HDPE, fiberglass, PVC, steel, rubber or similar flexible material, or concrete.
In another form the water selection apparatus may utilize a means to select a preferred water from one or more locations within or in the vicinity of the water body whereby the preferred water may be relocated by gravity or by pumping directly to the water quality barrier or to the extraction structure.
In embodiments of the invention, quality characteristics of the water are monitored as a function of depth within a water body and/or location about the water body, to enable identification of a depth or location or multiple depths or locations of water that may exhibit preferred water quality characteristics based on select parameter(s), and to permit an operator to be alerted of preferred water available for harvesting or extraction, and possible automatic selection of preferred water for harvesting or extraction. A process operator may be provided with a choice to select water from the main water body, based on dynamically measured water quality parameters, as a function of depth and/or location within the main water body, and a physical mechanism (gate, valve, window, slot, orifice, pipe, weir, flap, louver, port, entrance, inlet, skimmer, decanter, etc.) which can be controlled, opened, closed, raised, lowered, rotated, swiveled, angled, turned, and adjusted, as necessary to allow for water from the selected depth and/or location to be collected independently from water at depths above or below the selected depth or from location(s) separate from the selected location(s).
Further disclosure, objects, advantages and aspects of the present invention may be better understood by those skilled in the relevant art by reference to the following description of several embodiments thereof taken in conjunction with the accompanying drawings, which are given by way of illustration only and thus not limitative of the present invention, and in which:
Embodiments of the invention provide a method and apparatus that dynamically monitors water quality characteristics within a body of water; provides information to assist with identification and selection or directly identifies and selects water of preferred characteristic(s) for extraction/harvesting; separates and isolates this selected water from the water body—possibly within the water body; and provides for the possible treatment of selected water prior to extraction/harvesting. Thus, the process according to embodiments of the invention may be summarized as:
MONITOR→SELECT→SEPARATE→(TREAT→) HARVEST
Before describing the various embodiments of the invention, it is worthwhile explaining the context of application in further detail.
Considering that water near the reservoir floor may be undesirable, and water near the surface can become undesirable at certain times, there may be a depth of water that might present the purest, most desirable or least-expensive-to-treat water for harvesting. This “ideal water extraction depth” may change throughout the course of the day, week, month, and year, and may be isolated to just a few feet of water depth within the water column. It is therefore desirable to monitor the water quality within a reservoir as a function of depth, and have the capability to extract water at a select depth on a dynamic basis.
Considering also that there are times throughout the year that water “turns over” within the water body creating undesirable water quality characteristics, there may be one or more locations about the water body that provide ideal source locations that are remote from the extraction structure. It is therefore desirable to monitor the water quality within a reservoir as a function of location about the water body, and have the capability to relocate and extract water from selected locations on a dynamic basis.
The chart shown in
It should be noted that the preferred water for extraction may be water of any select characteristic, including contaminated water and/or water of poor quality. Contaminants can accumulate at certain depths at different times of the year. By extracting this water, the water body can be remediated over time while also allowing for the possible treatment of this contaminated water prior to discharge/extraction. It may be that mixing this contaminated water with water from a different depth may successfully remediate and/or treat this water prior to discharge. Additionally, the extraction and removal of this contaminated water from a water body may be timed to coincide with rain events or times when a spillway may be actively purging water.
The primary components employed in embodiments of the invention are outlined below.
Sampler and Monitor
An apparatus adapted for sampling and/or monitoring various water quality parameters as a function of depth within the water body. Parameters may include, but are not limited to, pH, dissolved oxygen, turbidity, organic carbon, color, chlorophyll, conductivity, hydrogen sulfide, dissolved metals, temperature, ORP, and so forth.
Selector
An apparatus that allows for selection of the depth and/or location at which water is able to flow from the water body to a harvesting device such as an intake structure having fixed-elevation extraction points (gate, pipe, weir, etc.). The selector may be incorporated in the barrier separator (see below) positioned between the bulk of the water body and the intake structure. The depth selection may be made on the basis of water characteristics measured by the sampler and monitor apparatus.
Barrier Separator
A rigid or flexible barrier installed in a water body to contain and separate water of differing and variable water quality characteristics.
Treatment Equipment
Solutions implemented within the confines of the barrier separator that treat or condition the selected water.
Control System
Monitors and controls all components in the system, potentially communicating through SCADA architecture.
A system 100 according to an embodiment of the invention is shown in diagrammatic isometric view in
The barrier 110 may comprise a baffle curtain or a permanent wall installed within the body of water, surrounding the existing harvesting (intake or outfall) structure. The barrier isolates water in the partitioned volume 114 from water in the reservoir and allows only water admitted through the selector interface to enter the partitioned volume. The barrier 110 is designed of a specific structural integrity and has features to ensure that water can always be admitted in and out of the enclosed volume without compromising the structural integrity of the barrier. For example, the barrier may incorporate features such as pressure relief, continuous bleed or other passive or active control means to avoid large pressure differentials across the barrier.
In embodiments of the invention the barrier separator may be in the form of a flexible baffle curtain constructed from nylon or the like. The baffle curtain may be supported by industrial strength floats at the top surface of the water, hanging down in the water column to the reservoir floor and secured by an anchor system concrete blocks and ballast such as steel chain sewn directly into a hem in the bottom of the baffle curtain. Baffle curtains suitable for the application may be sourced, for example, from JPS Industries of Bristol, N.H. U.S.A.
The system 100 also includes a water characteristic vertical profiling monitor 130 located in the main reservoir water body 112, preferably in the vicinity of the selector interface 118. There are a number of instrumentation solutions available to qualify water characteristics that may be suitable for use as the monitor 130 in embodiments of the invention. In general there are two options: one is to have an in-reservoir water sampling system that can sample water quality at various depths; the other is to pull water from various depths to the shore, or to a utility structure in the water body, and measure water quality parameters there using standard in-line or grab sample instruments.
As an example, suitable apparatus for performing the water characteristic monitoring functions are available from YSI Incorporated of Yellow Springs, Ohio U.S.A. Water quality profiling instrumentation, from YSI Systems, profiles the water at different depths throughout the Lake. YSI water quality sondes are equipped with sensors that measure dissolved oxygen, pH, turbidity, depth, temperature, specific conductance, and fluorescence. This monitoring apparatus may be based on an anchored floating platform with water monitoring instrumentation extending underneath and arranged to periodically sample and measure selected water characteristics at certain depth intervals in the water body. The frequency of sampling at each water depth may depend on the overall depth of the water body and the interval size, but might be expected to be of the order of hourly in a typical application. Data representing the measures water characteristics at the depth intervals can be hard-wired or wirelessly communicated to an on-shore installation (e.g. control and instrumentation equipment installation 140 illustrated in the drawings).
In operation, water quality and characteristics are measured and monitored outside the barrier separator 110 as a function of depth and/or location using the monitoring apparatus 130. Water monitoring data is communicated to the control and instrumentation equipment installation 140 which uses data processing techniques to analyze the data. Based on the data analysis, water at a specific depth is identified and selected for admission into the partitioned volume defined by the barrier 110 (preferred water). Preferred water from outside the barrier is admitted into the partitioned volume 114 through the selector interface 118. This is accomplished by selectively opening one or more of the selector gates 120 at depth(s) corresponding to that identified for the preferred water. In
Water exits the partitioned volume defined by the barrier separator typically through a harvesting structure such as an intake structure, outfall structure, pipe, channel or weir, which would have fixed-elevation extraction point(s). The ingress and egress of water is preferably controlled so that as water exits and enters the partitioned volume, the water level differential across the barrier separator is small enough to not compromise the structural integrity and function of the barrier or unduly limit the water flow into the extraction structure.
The selector interface 118 incorporates dynamically operated orifices (gates 120) of a specific minimal size, particularly in the vertical dimension, so as to allow sufficiently thin layers of like water of preferred quality from outside the main reservoir 112 into the partitioned volume 114 defined by the barrier 110. The selector gates 120 can be dynamically operated by manual, electrical, hydraulic, mechanical, or pneumatic means according to signals from the control equipment 140.
It is preferred that the selector gate openings are of relatively restricted dimension vertically so as to, in use, admit water from only a restricted depth range in the water body. For example, the selector openings may typically be 12″ to 18″ tall, and as wide as reasonably possible, for example at least 96″ wide. It is advantageous for the size of the opening to be as large as possible, but “thin” as reasonably possible in the vertical dimension. The reasoning for this is to allow transmission of water from small slices of the water column, but maintain a relatively small head-loss across the gate.
In embodiments, substantially every depth in the water body at the location of the selector interface will coincide with one or another selector gates. In the case of an intake water selector, respective selector gates may be positioned at most every “upper” depth/elevation, and down into the lower depths of a reservoir. For an outfall water selector it may be preferred to have gates through the lower levels only. The selector openings/gates may be arranged side by side, in a zig-zag pattern down the face of the selector interface incorporated in the barrier. This zig-zag pattern avoids having two consecutive gates on top of one another, which has specific benefits. It is preferred that the gates be spaced at least 12″ apart in the width direction, and possibly more than 24″. An exemplary arrangement is diagrammatically illustrated in
An example of a selector gate is and control apparatus 150 is shown in diagrammatic cross-section in
When air is introduced to the buoyancy chamber 160 through the tubing 170, water is correspondingly expelled through the vent hole 162. This increases the buoyancy of the chamber 160 which is attached at the lower end of the hinged gate and laterally offset somewhat. In view of the lateral offset in conjunction with an ‘optimum angle’ ((3) of the selector interface relative to the vertical, the increased buoyancy of the chamber 160 causes the gate 120 to pivot about the hinge 155 in the direction indicated by arrow 168 so that the bottom of the gate separates from the interface 118 to allow the water flow 113 through the aperture. Pivotal displacement of the gate 120 is limited by a tether 166.
In order to close the gate 120 the valve arrangement 175 is controlled so as to vent air from the tubing 170 to atmospheric pressure, as a consequence of which water is permitted to flow into the buoyancy chamber through the vent hole 162. When the buoyancy has been sufficiently reduced the gate pivots on its own force of weight to rest against the selector interface surface and stop water flow through the aperture.
In embodiments the barrier curtains are supported by industrial strength floats at the top surface of the water, and hang down in the water column to the reservoir floor. At the reservoir floor, there may be excess curtain that extends outward (or inward) or horizontally in an “L” fashion where ballast is placed on top of it to seal it to the reservoir floor. Over time, silt and solids can fill up interstitial spaces along the curtain. As the water level in a reservoir drops, the curtain folds on top of itself, still hanging from the surface floats. Therefore a mechanism may be provided to selectively close and prevent operation of one or more lower gates, if necessary, and if water levels drop, gates from the bottom up will be closed off as the curtain folds. Thus, it may also be desirable to include a remotely operable latch mechanism between the gate and the selector interface (not shown) in order to resist unintended opening due to, for example, flexible deformation of the barrier structure and interface that may occur because of variation in water depth. The system is designed to take into account this possibility of dropping water levels and the impacts it has on the barrier face-wall that incorporates the selector interface and gates. The angled orientation of the selector interface illustrated in
One of the benefits of the use of a barrier structure to define a partitioned volume is that the preferred water admitted to the partitioned volume may be treated before exiting through the intake structure, for example. The partitioned volume defined by the barrier may be designed with a dimensional size and layout so that water within the barrier can potentially be treated in a number of steps and/or methods before it harvesting, and with sufficient detention time relative to the maximum harvesting rate of the water. Water admitted into the partitioned volume may be subjected to various forms of treatment or conditioning, including but not limited to oxidation (ex. aeration, permanganate, peroxide, ozone, peracetic acid, chlorine, etc.), dissolved air/gas flotation, carbon contacting, pH adjustment, alkalinity adjustment, coagulation, flocculation, filtration, heating/cooling, and other forms of treatment.
Multiple zones of treatment may be incorporated within the barrier separator structure to allow for sufficient treatment prior to water exiting the partitioned volume. A system including additional features designed to facilitate such treatment processes is illustrated in
The preferred embodiments include the utilization of both a selector and barrier within the water body around or attached to an intake structure, outfall structure, or spillway, as this allows for several treatment benefits associated with the extraction/harvesting of water. However other forms are also contemplated, such as an alternative embodiment as illustrated in
Another form of alternate embodiment as illustrated in
In use of the system 500 the water quality monitor 530 periodically measures water quality metrics using the sensors or sampling devices 532 at the respective depths/locations within the water body 512. Data concerning the measured water quality metrics are communicated to the control processor 540. Based on the measured water quality metrics at various depths/locations and predetermined desired water quality characteristics, the control processor 540 communicates with the selector gate controller 550 information as to which of one or more of the selector gates 520 should be opened/closed in order to admit water from the water body 512 into the partitioned volume 514. The selector gate controller 550 controls opening and closing of the selector gates 520 and/or outlet gate 506 accordingly.
Those skilled in the art will appreciate that features of the systems 500, 600 may be interchangeable. For example, discrete depth water quality measurement may be used in a system with a single, variable control water selector inlet, and vice versa. Moreover, as previously described, in certain embodiments the selector gate apparatus may be directly coupled to the outlet gate of the intake structure, without a partitioned volume in between.
In a variation referred to herein as an ‘outfall’ embodiment the system may be used to monitor and control the withdrawal of selected water (quality) via a spillway or overflow. The intent is to permit controlled release of selected water, in this case typically having unfavorable characteristics (i.e. to get rid of the bad water in the reservoir). The outflow embodiment may be useful for improving or creating certain reservoir overall water quality condition and/or to affect downstream receiving waters. The mechanisms for monitoring and selecting that have been described in the specification in relation to the various other embodiments are also applicable to this outfall embodiment.
Earlier embodiments have predominantly been described in the context of a barrier formed from a flexible baffle curtain however, as mentioned, a fixed rigid structure may also be employed.
The water harvesting plant intake gates that are normally used in this water body are those at elevation 618 ft and 623 ft (typically two gates are open to meet hydraulic requirements). Prior to installation of the experimental water selector apparatus, the WTP would experience raw water quality impacts associated with algae, i.e. taste & odor and TOC, as in this case, the chlorophyll levels would be about 10 μg/L transferred to the plant where pre-chlorination takes place. To respond to these conditions the plant typically dosed 18 ppm carbon prior to the rapid mix.
With the water selector apparatus installed and configured to provide preferred water from elevation 612 ft, the plant realized an improvement in raw water quality and was subsequently able to reduce the carbon dose to 12 ppm, a 33% decrease. While the preferred raw water had a slightly higher turbidity, the level did not require an increase in coagulant (alum) dosing.
In the transition from autumn to winter in the region, the water body typically experiences seasonal turnover with cyclical colder and warmer days leading to relatively little stratification. However, this is also usually a wet time of year and rain events have historically proven especially impactful. The water body is in the vicinity of a large metropolitan area and is influenced by discharges and runoff. The water body typically turns brown and the turbidity influent to the plant can spike dramatically during rain events upstream along the river which feeds water into the reservoir. In late December 2015 a rainfall event measuring less than 1 inch in the upstream metropolitan area led to a turbidity spike at the plant to over 70 NTU and a corresponding increase in alum dose to 34 mg/L (over 50% increase). In December during the period of experimental observation, a similar rain event occurred in the metropolitan area and as a result a turbidity increase in the water body occurred.
With reference to
As seen in the graph, the turbidity spiked to over 30 NTU from about 3 ft below the surface to about 20 ft down on December 24. By selecting one of the lower gates, i.e. gate 13, 14 or 15, a much smaller turbidity increase would be experienced providing for less required adjustment for coagulation and a lower risk of a poor treatment outcome. By December 28, the turbidity had approached a new de-stratified profile.
Even during winter months with colder air and water temperatures, cyclical temperature transients and the resulting reservoir turnover and de-stratified profile, the water selector apparatus according to embodiments of the present invention can operate to smooth out water quality transitions caused by temperature swings and rain events.
The structure and implementation of embodiments of the invention has been described by way of non-limiting example only, and many additional modifications and variations may be apparent to those skilled in the relevant art without departing from the spirit and scope of the invention described.
Throughout this specification and the claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017902179 | Jun 2017 | AU | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2018/050617 | 2/1/2018 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62454351 | Feb 2017 | US |
