Presently, wastewater treatment plants employ multiple steps in processing wastewater to meet effluent water quality requirements. Examples of such plants are discussed in U.S. Pat. No. 8,268,169 B2, titled “Membrane Bioreactor (MBR) and Moving Bed Bioreactor (MBBR) Configurations for Wastewater Treatment”, and U.S. Patent Publication 2015/0175454 A1, titled “Recycling Activated Sludge by Hydrodynamic Separator (HDS) to Enable High MLSS Bioreactor to Process High Influent Flow and/or High Strength Wastewater.”
In wastewater treatment plant design for suspended growth activated sludge systems, the end of aeration basins are often outfit with weirs and effluent channels for hydraulic control and solids distribution purposes. From effluent channels the mixed liquor suspended solids (MLSS, or activated sludge) are sent to clarifiers or membrane bioreactors (MBRs) for solids separation. The thickened MLSS or activated sludge solids from these devices are either recycled back to seed the influent wastewater, or are wasted. Clarified effluent is disinfected and discharged. Clarifiers and MBRs are sized to accommodate certain concentrations and flow rates (solids flux).
It is considered useful to design a wastewater treatment plant which lowers the concentration of MLSS or activated sludge provided to operational units that act to separate MLSS or activated sludge solids, e.g., clarifiers, MBRs, etc. of the treatment plant. This allows for a significant reduction in the size and/or number of such operational units, in turn permitting for a more compact and efficient wastewater treatment plant.
The following articles, and co-pending and commonly assigned applications, the disclosures of each being totally incorporated herein by reference, are mentioned:
U.S. Published Application Publication No. 2009/0050538, entitled, “Serpentine Structures for Continuous Flow Particle Separations”, by Lean et al:; U.S. Published Application Publication No. 2008/0128331, entitled, “Particle Separation and Concentration System”, by Lean et al.; U.S. Published Application Publication No. 2008/0230458, entitled, “Vortex Structure for High Throughput Continuous Flow Separation”, by Lean et al.; U.S. Published Application Publication No. 2009/0114601, entitled, “Device and Method for Dynamic Processing in Water Purification”, by Lean et al.; U.S. Published Application Publication No. 2009/0114607, entitled, “Fluidic Device and Method for Separation of Neutrally Buoyant Particles”, by Lean et al.; U.S. Pat. No. 8,404,093, entitled, “Flow De-Ionization Using Independently Controlled Voltages”, by Armin R. Volkel et al.; U.S. Patent Application Publication No. 2010/0314323, entitled, “Method and Apparatus for Continuous Flow Membrane-Less Algae Dewatering”, by Lean et al.; U.S. Published Application Publication No. 2009/0283455, entitled, “Fluidic Structures for Membraneless Particle Separation”, by Lean et al.; U.S. Pat. No. 8,931,644 B2, entitled “Method and Apparatus for Splitting Fluid Flow in a Membraneless Particle Separation System”, by Lean et al.; U.S. Patent Application Publication No. 2011/0108491, entitled, “Desalination Using Supercritical Water and Spiral Separation”, by Lean et al.; U.S. Published Application Publication No. 2010/0072142, entitled, “Method and System for Seeding with Mature Floc to Accelerate Aggregation in a Water Treatment Process”, by Lean et al.; U.S. Patent Application Publication No. 2010/0314263, entitled, “Stand-Alone Integrated Water Treatment System for Distributed Water Supply to Small Communities”, by Lean et al.; U.S. Patent Application Publication No. 2010/0314325, entitled, “Spiral Mixer for Floc Conditioning”, by Lean et al.; U.S. Patent Application Publication No. 2010/0314327, entitled, “Platform Technology for Industrial Separations”, by Lean et al.; U.S. Patent Application Publication No. 2012/0145647, entitled, “Electrocoagulation System”, by Volkel et al.; U.S. Pat. No. 8,518,235, entitled, “All-Electric Coagulant Generation System”, by Volkel et al.; U.S. Pat. No. 8,268,169, entitled, “Membrane Bioreactor (MBR) And Moving Bed Bioreactor (MBBR) Configurations For Wastewater Treatment”, by Meng H. Lean et al.; U.S. Patent Application Publication No. 2012/0152855, entitled “System and Apparatus for Seawater Organics Removal”, by Lean et al.; U.S. Patent Publication No. 2014/0197113-A1, entitled “Systems And Apparatus For Removal Of Harmful Algae Blooms (HAB) And Transparent Exopolymer Particles (TEP)” by Volkel et al.; U.S. Patent Publication No. 2014/0367348-A1, entitled “HDS Channel Exit Designs for Improved Separation Efficiency”, by Volkel et al.; and U.S. Patent Publication No. 2015/0175454 A1, titled “Recycling Activated Sludge by Hydrodynamic Separator (HDS) to Enable High MLSS Bioreactor to Process High Influent Flow and/or High Strength Wastewater.”
A method of processing wastewater through a wastewater treatment plant includes providing wastewater to an aeration basin configured to receive the wastewater. Then suspended-growth biomass is produced, including at least one of activated sludge and mixed liquor suspended solids (MLSS) that is enriched for and collected within the aeration basin and a clarifier system and is used to degrade constituents in the wastewater. Portions of the activated sludge and/or MLSS are passed from the aeration basin over a weir to provide an aeration basin effluent channel positioned in operational association with the weir. The activated sludge and/or MLSS is received from the aeration basin effluent channel into inputs of a hydrodynamic separator (HDS) arrangement which is in operative connection with the aeration basin effluent channel. The HDS arrangement includes a plurality of individual curved channels, formed in a stack operative to generate flow fields comprising first portions and second portions of the activated sludge and/or MLSS. The activated sludge and/or MLSS is output from the HDS arrangement via HDS output openings, and the activated sludge and/or MLSS is split at the HDS output openings by a splitter plate positioned at or within the output openings of the HDS. The splitter plate directs the activated sludge and/or MLSS with the first portion flowing to a concentrate channel and the second portion flowing to an effluent channel. The activated sludge and/or MLSS in the concentrate channel is cycled back to the aeration basin or an aeration influent channel, and the activated sludge and/or MLSS of the effluent channel is passed forward for further clarification operations.
In another embodiment, a wastewater treatment plant incorporates a particle separation device. The plant includes an aeration basin having an input configured to receive wastewater. A weir directs the MLSS and/or activated sludge from the aeration basin to an aeration basin effluent channel positioned in approximate association to the weir to receive at least one of activated sludge and MLSS coming over the weir from the aeration basin. A hydrodynamic separator (HDS) arrangement includes a plurality of curved channels having inputs configured to receive the activated sludge and/or MLSS from the aeration basin effluent channel output and a plurality of outputs. The HDS arrangement is formed as a stack of individual channels operative to generate flow fields comprising first portions and second portions, the first and second portions of the flow field being formed by flow drive forces generated by the flow field in the curved channels. The flow driven forces includes centrifugal forces and at least low pressure forces or buoyancy forces; and a splitter mechanism positioned at or within the output openings of the HDS arrangement for directing a split of the activated sludge and/or MLSS such that the first portion flows on a first path and the second portion flows on a second path.
In another embodiment, a method is provided for processing wastewater through a wastewater treatment plant. Wastewater is provided to an aeration basin configured to receive the wastewater. Suspended-growth biomass is produced, including at least one of activated sludge and mixed liquor suspended solids (MLSS) that is enriched for and collected within the aeration basin and a clarifier system, and used to degrade constituents in the wastewater. Portions of at least one of the activated sludge and MLSS is passed from the aeration basin over a weir to an aeration basin effluent channel positioned in operational association with the weir, and configured to receive the activated sludge and/or MLSS coming over the weir from the aeration basin. The activated sludge and/or MLSS is received from the aeration basin effluent channel into inputs of a hydrodynamic separator (HDS) arrangement in operative connection with the aeration basin effluent channel. The HDS arrangement includes a plurality of individual curved channels, formed as a stack of the individual curved channels and operative to generate flow fields comprising first portions and second portions of the activated sludge and/or MLSS. The first and second portions of the activated sludge and/or MLSS flow being formed by flow drive forces generated by flow fields in the curved channels. The flow driven forces including centrifugal forces and at least low pressure forces or buoyancy forces. The activated sludge and/or MLSS being passed through the curved channels of the HDS arrangement by at least one of gravitational forces and hydrostatic pressure of the aeration basin effluent channel, and the inputs of the HDS arrangement. The activated sludge and/or MLSS from the HDS arrangement is output via HDS output openings. The activated sludge and/or MLSS at the HDS output openings is split by a splitter mechanism positioned at or within the output openings of the HDS arrangement for directing a split of the activated sludge and/or MLSS. The first portion flowing to a concentrate channel on a first path and the second portion flowing to an effluent channel on a second path. The activated sludge and/or MLSS in the concentrate channel is cycled back to the aeration basin or an aeration influent channel, and the activated sludge and/or MLSS of the effluent channel is passed forward for further clarification operations.
Presented is a concept for integrating a hydrodynamic separator (HDS) stacked channel arrangement into aeration basin effluent channels to allow for solids separation to lower activated sludge and/or MLSS concentrations (HDS effluent) sent to secondary clarifiers or MBRs ideally via gravity, but possibly via pumping. Based on the large particle sizes of the activated sludge and/or MLSS flocs, low pressure HDS channels are used, which can be operated solely on hydrostatic pressure differences within the system. The HDS/effluent channel design has a flow-splitter device which allows for rapid cleaning as well as adjustable flow and solids distribution. Flow from the HDS system that has the higher concentration of activated sludge and/or MLSS (HDS concentrate) is returned to the head of the aeration basin via pumping. Optimal performance of the HDS channels is controlled through the water levels in input and output chambers.
In the present disclosure inlets to the hydrodynamic separator (HDS) stacked channel arrangements or units are located at or near the bottom of aeration basin effluent channels such as shown in
One embodiment of the present application is illustrated by cross-sectional view of 300 of
It is noted that in
Turning to
The movable nature of splitter 406 (320) also allows for control of the flow entering the distinct separate channels 316, 318 (
Turning to
The activated sludge and/or MLSS flows over weir 506, which in certain embodiments is a metal or other rigid structure. In this embodiment the weir is a piece of sheet metal. However, weirs are configured in other forms and materials, and these are to be understood to be included in these concepts. The activated sludge and/or MLSS flows over weir 506 into aeration basin effluent channel 508. A bottom surface 508a of the aeration basin effluent channel 508 in operative connection to a HDS stacked channel arrangement 510. The HDS channels are formed as substantially half- to quarter-turn channels, where HDS inlets or input openings 512 are positioned to move the activated sludge and/or MLSS into the HDS arrangement 510. This configuration uses gravitational forces and hydrostatic pressure to move the activated sludge and/or MLSS into and through the channels to the HDS arrangement exits or output openings 514. The operation of the HDS stacked channel arrangement 510 separates the activated sludge and/or MLSS into two streams, including a less concentrated activated sludge and/or MLSS portion (HDS effluent) and a more concentrated activated sludge and/or MLSS portion (HDS concentrate). In this particular embodiment, at the HDS exits or output openings 514, a splitter plate 520 is provided, to control the output flow of the activated sludge and/or MLSS to either a HDS concentrate channel 522 or an HDS effluent channel 524. As can be seen, the splitter plate 520 operationally extends the length of the HDS stacked channel arrangement (i.e., modules or stacks of HDS channels) 510 to insure that the two streams from the HDS exits do not co-mingle. The splitter plate 520 is shown in a retracted position in
It is noted that in
In this embodiment, activated sludge and/or MLSS in the HDS concentrate channel 616 is moved through recycle line 620 which flows the concentrated activated sludge and/or MLSS back to the inlet of aeration basin 602 for further processing. In the present embodiment, a pump 622 is optionally shown to assist in moving the concentrated activated sludge and/or MLSS from the HDS concentrate channel 616 to the inlet of aeration basin 602.
With regard to the dilute activated sludge and/or MLSS in the HDS effluent channel 614, as the liquid level increases, it spills over weir 624 into a collection channel 626, which includes a lower output 628, providing the HDS effluent to clarifiers (i.e., either directly or through a distribution box, as is known in the art).
It is shown in this embodiment, that the splitter 614 is a movable as well as removable component. More particularly, provided is a motor 630, which operates with a vertical geared mechanism 632, and a motor 634 which operates with a horizontal geared mechanism 636. These arrangements are in operative connection with splitter 614 to move the splitter in vertical and horizontal directions. For example, splitter 614 is movable-vertically into close relationship with the HDS channel openings 612. In some instances, the splitter may be placed immediately outside of the openings 612, whereas in alternative embodiments, dependent on particular implementations, the splitter 614 may be moved (inserted) within the opening (provided the HDS channel exits are notched to accommodate the splitter) such that the splitting of the wastewater is occurring prior to fully exiting the HDS opening 612. Additionally, the splitter 614 may be moved horizontally in the left and right directions whereby the amount of wastewater entering the HDS concentrate channel 616 and the HDS effluent channel 618 is controlled.
It is mentioned, the movement of the splitter in the left or right directions is altered dependent on process control objectives. When there is a lower concentration of activated sludge and/or MLSS in the aeration basin effluent channel, it may be desirable to move the splitter 614 to the left, whereby more of the dilute activated sludge and/or MLSS is provided to the HDS effluent channel 618. Whereas, when there is a high concentration of activated sludge and/or MLSS in the aeration basin effluent channel, the splitter 614 could be moved to the right, whereby less of the dilute activated sludge and/or MLSS is flowed into HDS effluent channel 618, and more of the concentrated activated sludge and/or MLSS is being recycled back through the system for further processing via the HDS concentrate channel 616. Having the ability to adjust the flow split and hence affect the distribution of solids in the system allows the operator to have greater control of both the inventory of activated sludge and/or MLSS solids in the aeration system and also the performance of the solids separation units (e.g., clarifiers) downstream of the aeration basins.
It is noted that in
View 800 of
Also shown in
In an alternative embodiment, each of the output openings include a slit that matches the profile of the tip end 812, to allow the tip end 812 to be placed within the output openings, and accommodates any movement of the splitter across the exits that is intended to alter the flow split.
Turning to
Activated sludge and/or MLSS from the HDS effluent channel 912 is flowed by line 918 to a clarifier feed well 920 located inside secondary clarifier 922. The secondary clarifier 922 includes a sludge rake 924 which moves settled, thickened sludge out of the secondary clarifier 922 into activated sludge pump return line 926 and the pump 927, back into the beginning of aeration basin 902. With continuing attention to
As noted previously, various drawings used herein are side or cross-sectional views looking “into the paper”. It is to be understood the described treatment plants (or portions thereof) commonly include multiple repetitions of the components that have been discussed, as well as others (e.g., multiple aeration basins, weirs, aeration basin effluent channels, HDS stacked channel arrangements, etc.). These parallel process units are often called trains.
When there are multiple trains with more than one clarifier, flow is often first routed through a clarifier distribution box. The distribution box may be outfit with adjustable weirs and gates which allows for distribution of activated sludge and/or MLSS to clarifiers. As an overall intent is for wastewater treatment plants to flow by gravity, using as little pumping as possible, having adjustable weirs allows for final flow control tweaking (e.g., in case a wall is too high, settles after construction, is not level, etc.). Further the gates allow operators to shut flow to one or more clarifiers to take them out of service for maintenance.
The right angled arrows, e.g. 932 (numbered once) although there are numerous other arrows is intended to show the water surface elevation at specific locations.
As mentioned above, while a number of the drawings illustrate views that appear to show a single aeration basin and/or possibly single clarifier; in wastewater treatment plants there are commonly multiple ones of these and other components. In these plants, it is common to use the previously discussed distribution box (D-Box).
Turning to 11A, illustrated is a cutaway drawing of a typical secondary clarifier arrangement 1100 (http://www.mon-env.com/water-and-wastewater-treatment/circular-clarifiers/circular-clarifiers-secondary), emphasizing complexity beyond that of a simple holding tank. Particularly provided is an influent area 1102 for receiving the fluid flow (e.g., activated sludge and/or MLSS), as well as a sludge discharge area 1104 near the bottom of the clarifier 1100. An assembly also operating near the bottom surface of the clarifier includes a riser pipe 1106, a rake arm 1108 and a scraper blade 1110. Along the outer perimeter of the clarifier 1100 is an effluent launder 1112, a v-notched weir 1114, scum baffle 1116, as well as an effluent trough 1118 and a scum trough 1120. Operating in conjunction with the elements at the outer surface of the clarifier is a skimmer arm 1122. In the center shaft area of the clarifier 1100 is a sludge box 1124 and feedwell 1126, along with a drive motor 1128 used to operate the various components. Also shown in this figure, which emphasizes the large size of clarifiers, is a gate walkway 1130 which a technician may use to gain access to the center of the clarifier 1100 even when it is filled with fluid. This allows the technician to possibly provide maintenance to the drive motor 1128 or perform other maintenance operations.
Turning to
Turning to
Again, activated sludge and/or MLSS from aeration basin 1204 spills over a weir 1206 such that the activated sludge and/or MLSS flows to aeration basin effluent channel 1208. In this embodiment the HDS stacked channel arrangement 1202 is submerged within at least a HDS concentrate channel 1212 and/or a HDS effluent channel 1214. In this arrangement gravitational forces and hydrostatic pressure act to flow the activated sludge and/or MLSS to HDS input openings 1216 located at or near the bottom on aeration basin effluent channel 1208 and passes through the HDS stacked channel arrangement 1202 to the output openings 1217. The HDS concentrate stream is directed to the concentrate channel 1212, while the HDS effluent stream is directed to the HDS effluent channel 1214 by use of splitter 1218.
Thereafter, as previously discussed the activated sludge and/or MLSS from the HDS concentrate channel 1212 is moved back to the aeration basin for further processing, and the activated sludge and/or MLSS in the HDS effluent channel 1214 is moved through additional portions of the wastewater treatment plant for further processing.
In order to maintain separation of the activated sludge and/or MLSS in the concentrate channel 1212 and the effluent channel 1214, wall 1226 is provided and abuts 1228 an outer surface of the HDS stacked channels 1202. At this abutment location1228 a sealing material is used to avoid leakage of the activated sludge and/or MLSS between the two channels 1212, 1214. In some embodiments stacks of HDS channels 1202 and wall 1226 are formed as a single structure.
Also as the HDS channel stack 1202 is submerged in the channels 1212, 1214, gaps are provided between selected channels of the HDS stacked channel arrangement 1202 in the concentrate channel 1212 to allow the activated sludge and/or MLSS to flow, and the gaps are sealed (or not otherwise provided) for the portion of the submerged HDS stacked channel arrangement 1202 within the effluent channel 1214. By blocking the gaps in this way, intermixing of the separate wastewater streams is avoided. The gaps are explained and shown in more detail in
With continuing attention to
It is noted that in
The movable nature of the splitter 1302 also allows for control of the flow entering the separate channels 1212, 1214 (e.g.,
Turning to
In the embodiment of
It is noted that in
In each of the forgoing embodiments, the inputs to the HDS stacked channel arrangements make connection the aeration basin effluent channel at the bottom surface of the aeration basin effluent channel or in a sidewall substantially at or near the bottom, i.e., within the lower 10% or less portion of the side wall. A specific design location will depend on the available hydraulic head, the size and depth of the aeration basin effluent channel when present, the design and therefore the pressure requirements of the stack of HDS channels being used. In either case, the intent is to have the liquid level of the aeration basin effluent channel provide the driving head that forces activated sludge and/or MLSS through the stack of HDS channels. Too much or too little pressure (as hydraulic head) will prevent the stack of HDS channels from functioning well or at all, because the necessary flow rates and hydraulic conditions cannot be met or maintained. It is also noted that with regard to the embodiments of
Turning to
Turning to
With attention to
With continuing attention to
Depending on the channel geometry and the flow rate the particles are concentrated either at the inner or the outer side wall.
Turning to
As it is undesirable for the HDS channels within the HDS arrangement to clog, sensing the water levels, the solids concentrations, the hydrostatic pressure, or the turbidity in the HDS concentrate and HDS effluent channels allows an indirect evaluation of whether the HDS channels within the HDS arrangement is clogged. For example, water (e.g., activated sludge and/or MLSS) rising above a pre-determined acceptable level in one channel compared to the other may be an indication of clogging. Changes in water level are also indicated by changes in hydrostatic pressure within the HDS concentrate and HDS effluent channels, and differences in hydrostatic pressure outside a pre-determined acceptable level in one channel compared to another may be an indication of clogging. Also for example, the solids concentration in one channel compared to the other being within certain proximity (i.e., if the concentrations are the same in both channels) may be an indication of clogging. Solids concentration is also indicated by turbidity within the HDS concentrate and HDS effluent channels, and differences in turbidity are within a certain proximity (i.e., if the turbidity readings are the same in both channels) may be an indication of clogging. In either situation, the output from the sensors 1907, 1908 and 1909 is provided to a controller 19110 specific to the parameter being monitored. The controller 1910 includes an alarm or some other notification that indicates to an operator that the limits are exceeding a predetermined set-point. This provides the operator with information that may indicate clogging is occurring and gives the operator with an opportunity to replace and/or clean the splitter 1906. The controller 1910 may actuate splitter motor 1911 to raise, lower, or otherwise initiate a cleaning sequence directly.
In
With reference to
As previously discussed, a splitter 2008 is positioned to split activated sludge and/or MLSS flow after an HDS channel that is not bifurcated. In this embodiment to control the activated sludge and/or MLSS flow to separator 2002, various data items are collected. These data items include for example, pressure, bandwidth and flow velocity. Additionally, sensors for temperature, solids concentration, and viscosity may also be used to collect desired data. Such data items are in this embodiment fed to operation controller 2014, which in turn provides control signals to input controller 2006. Thus, the presently described embodiments may include various sensing on feedback control to allow for the enhanced operation of the fluid flow. Those sensors may also be provided on the channels to detect velocity variations. This data will then be used to feedback to necessary pumps or control valves to maintain a desired constant flow rate, and hence velocity. A pressure sensor can also be provided to adjust the flow rate in channels to minimize band dispersion and to maximize flow recovery. Temperature sensors may be used to correct fluidity operation and the viscosity sensors being used to correct for adjustments in operation parameters. Solids concentration sensors may be used to adjust splitter location to assist in the distribution of solids between the aeration basin and the clarifier, providing improved process control. Feedback control may also be employed to trigger cleaning routines.
Turning now to particular operation characteristics, while wastewater treatment plants may have distinct operational characteristics to which the present concepts may be applied embodiments described herein are intended to be configured to at least operate within flow rates per channel of 0.2 to 2 liters per minute (0.865 L/min typical), where an HDS channel design might have a typical cutoff size (minimum separable particle size) of 20-200 μm (100 μbeing the typical cutoff size). The largest intended particle size might be in the range of 0.1 mm-1 mm (with 0.4 mm being the typical largest particle size). The HDS channels are in certain embodiments considered to have a radius of curvature of between 100 to 1000 mm (with about 285 mm being a typical curvature). It is also noted that the starting solid concentration (i.e., activated sludge and/or MLSS) is in the range of 100-10,000 mg/L (with 3000 mg/L being a typical concentration). In addition, the operating pressure (psi) within the system is in the range of 10 psi to 0.1 psi (with 0.6 psi being a typical operating pressure). The foregoing are perceived by the inventors as the ranges that are intended to be used in systems such as being described herein. More particularly, a specific design that has been specifically tested, includes the following characteristics: flow rate per channel is 600 ml/min, with a particle cutoff size being approximately 70 μm, with the largest particle size being approximately 0.25 mm, with the channels having a radius of curvature of approximately 198 mm (having starting/inlet concentrations that have been tested being between 2000 and 9000 mg/L), and the system having an operating pressure of approximately 1.2 psi (which can be provided by approximately a 3 foot elevation raise). It is understood that the larger the channels of an HDS arrangement the lower the pressure needed to have wastewater flow through the system. With regard to the particles in the wastewater, a particular ratio is that the HDS channel height is approximately four (4) times the size of the largest particles in a solution, and the HDS channel width is between approximately four (4) to twenty (20) times the HDS channel height.
It is to be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also, that the various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.