U.S. patent application number 14/855500 was filed with the patent office on 2016-03-31 for system for mixing industrial waste water within a gravity settling tank.
The applicant listed for this patent is ClearCove Systems, Inc.. Invention is credited to Timothy D. McCrossen, Kimberly A. Miller, Terry Wright.
Application Number | 20160089619 14/855500 |
Document ID | / |
Family ID | 55583443 |
Filed Date | 2016-03-31 |
United States Patent
Application |
20160089619 |
Kind Code |
A1 |
Wright; Terry ; et
al. |
March 31, 2016 |
SYSTEM FOR MIXING INDUSTRIAL WASTE WATER WITHIN A GRAVITY SETTLING
TANK
Abstract
A system for static mixing in a waste water settling tank to
increase the percentage of recovery of entrained solids from the
waste water comprising a settling tank having a hopper bottom
defining a sludge hopper, a deflector dome centrally disposed
within the space contained in the hopper bottom, and an inlet pipe
for introduction of waste water containing second entrained solids
into the settling tank and having a discharge outlet in proximity
to the underside of the deflector dome. Influent waste water is
directed vertically upward into the center of the deflector dome
which distributes the influent radially into contact, preferably
turbulent, with previously introduced waste water containing first
entrained solids to cause coalescence of the first and second
entrained solids to form larger particles having increased settling
velocity.
Inventors: |
Wright; Terry; (Rochester,
NY) ; Miller; Kimberly A.; (Oneonta, NY) ;
McCrossen; Timothy D.; (Rochester, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ClearCove Systems, Inc. |
Victor |
NY |
US |
|
|
Family ID: |
55583443 |
Appl. No.: |
14/855500 |
Filed: |
September 16, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62055061 |
Sep 25, 2014 |
|
|
|
Current U.S.
Class: |
210/519 |
Current CPC
Class: |
C02F 1/006 20130101;
C02F 2001/5218 20130101; C02F 1/66 20130101; C02F 2001/007
20130101; C02F 2103/32 20130101; B01D 21/2427 20130101; B01D
21/0087 20130101; C02F 1/52 20130101; C02F 2209/10 20130101; C02F
2209/08 20130101; C02F 2209/06 20130101; B01D 21/2405 20130101 |
International
Class: |
B01D 21/00 20060101
B01D021/00; B01D 21/24 20060101 B01D021/24 |
Claims
1. A system for static mixing in a waste water settling tank to
increase the percentage of recovery of entrained solids from the
waste water, comprising: a) a settling tank having a hopper bottom
defining a sludge hopper; b) a deflector dome disposed within the
space contained in said hopper bottom; and c) an inlet pipe for
introduction of waste water into said settling tank, said inlet
pipe having a discharge outlet in proximity to the underside of
said deflector dome.
2. A system in accordance with claim 1 wherein said deflector dome
is centrally disposed within said space.
3. A system in accordance with claim 1 further comprising a
distribution cone centrally disposed within said dome.
4. A system in accordance with claim 3 wherein said deflector dome
and said distribution cone define a deflector assembly.
5. A system in accordance with claim 3 wherein the diameter of said
distribution cone is at least equal to the inner diameter of said
discharge outlet.
7. A system in accordance with claim 3 wherein said discharge
outlet is off-spaced vertically from said distribution cone by a
distance equal to at least one-half the radius of said discharge
outlet.
8. A system in accordance with claim 1 wherein said inlet pipe is
arranged such that waste water discharged from said discharge
outlet is directed upwards into said deflector dome.
9. A system in accordance with claim 1 wherein said settling tank
is cylindrical and wherein said hopper bottom is conical.
10. A system in accordance with claim 9 wherein the included cone
angle in said conical hopper bottom is 60.degree..
11. A system in accordance with claim 1 wherein the lower rim of
said deflector dome is positioned about 12 inches from the bottom
of said sludge hopper.
Description
RELATIONSHIP TO OTHER APPLICATIONS AND PATENTS
[0001] The present invention claims priority from pending U.S.
Provisional patent application, Ser. No. 62/055061, filed Sep. 25,
2014, titled "System for Treating Industrial Waste Water", the
disclosure of which is incorporated herein by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to systems for processing
waste water; more particularly, to such systems for handling
biologically digestible materials in waste water generated
typically in foods and potables manufacturing and serving, e.g.,
bakeries, breweries, dairies, restaurants, wineries, and the like;
and most particularly, to a simple, small volume system for
settling solids and adjusting pH in food process waste water to
meet waste water quality standards for discharge into a municipal
sewage system, including a method for static mixing in an
industrial waste water settling tank to increase the percentage of
recovery of entrained solids from the waste water.
[0003] As used herein, the term "food materials" should be taken to
mean any and all biologically digestible organic materials, without
limit; the term "food process waste water" should be taken to mean
excess water and by-products, components beyond just water itself,
used in the manufacture and/or use of food materials, which water
must be treated to remove a portion of the dissolved and/or
suspended food materials before being either sent to a waste water
treatment facility, otherwise discharged to the environment, or
hauled away for offsite handling.
[0004] Foods and potables manufacturing and handling typically
require large volumes of input process water and generate
substantial levels of biologically digestible materials dissolved
and suspended in their resultant waste process water. Additionally,
the pH of such waste water may be substantially acidic or alkaline.
When directed without pre-treatment to municipal waste water
treatment facilities, such waste water can place a heavy and costly
load on municipal waste treatment facilities. As a result, many
communities impose a substantial cost on companies that generate
such waste waters in the course of their operations. It is known to
monitor the level of food materials in waste water output of
companies and to levy a sewer surcharge on the companies
accordingly. Many of these companies, for example,
"microbreweries", are relatively small in capitalization and output
and thus are in need of a relatively inexpensive method and
associated apparatus for pre-treating of process waste water to
remove a substantial percentage of suspended food materials
therefrom before the process waste water is discharged to a
municipal sewer system. Fortuitously, the total volume of process
waste water generated by many such operations is relatively small,
on the order of 1000 gallons/day or less, and therefore is amenable
to treatment by a method and apparatus in accordance with the
present invention. Larger scale operations can also be supported by
scaling up with multiple modules of the present invention.
[0005] Note: "Biological Oxygen Demand" (BOD), also known as
Biochemical Oxygen Demand and as used herein, is the amount of
oxygen needed by aerobic microorganisms to decompose all the
organic matter in a sample of water; it is used in the eco-sciences
as a measure of organic pollution. As used herein, the term "BOD"
also means more generally the unit volume load, both dissolved and
suspended, of such organic material in waste water.
[0006] Further, Total Suspended Solids (TSS) is a water quality
measurement which, as used herein, is expressed as the unit volume
load of suspended solids, both organic and inorganic, in water. It
is listed as a conventional pollutant in the U.S. Clean Water
Act.
EXAMPLE
[0007] The following example is directed to the characteristics and
treatment of waste water generated by breweries. It should be
understood that the disclosed method and apparatus are also
well-suited to similar usage in many other types of industrial and
agricultural manufacturing and use as noted above.
[0008] Breweries have unique effluent characteristics and specific
treatment needs. Breweries typically have Biological Oxygen Demand
(BOD) levels of 2,000-4,000 mg/l and Total Suspended Solids (TSS)
levels of 2,500-3,500 mg/l. These solids have higher densities than
water and readily settle out, and much of the dissolved organic
load can also be precipitated out by dosing the waste water with
coagulants or flocculants. Brewery effluent can typically have a pH
range of 2 to 13, depending on what process is taking place in the
brewery. The pH may have to be adjusted on occasion to meet
municipal requirements and also be bought into optimum range for
effective chemical treatment. Brewery effluent can have fluctuating
levels of BOD, TSS and pH. There is also a chance that occasionally
the brewery may have to waste a batch of beer, discharging the
batch and introducing high levels of BOD into a municipal
system.
[0009] Brewery waste water comprises several contributors to the
total BOD and TSS load. Most of these are organic in nature and
pose no serious threat to public health.
[0010] Yeast, spent grain, and hops are the building blocks of
beer. Most of the wastes from these components typically are side
streamed in the brewery and diverted as feed for farm animals.
Inevitably, some of that waste also will be flushed into the drain
and thereby raise the BOD and TSS levels of the process
effluent.
[0011] Wort is the liquid that will become beer once the yeast is
added. Wort comprises fermentable and unfermentable sugars as well
as starches and proteins. Because wort is rich in dissolved sugar,
it is the primary contributor of BOD and SBOD (soluble BOD).
[0012] Fermented beer left in tanks after transfers and lost during
packaging also contributes to the BOD and SBOD of the effluent
leaving the brewery.
[0013] Beer has a characteristically low pH (typically 4-5.5) that
can reduce the overall pH of the waste water.
[0014] For cleaning chemicals, breweries typically rely on caustic
solutions for removing organic deposits from their process tanks.
Acid is used on occasion, as are iodine-based sanitizers and
peracetic acid for sanitizing tanks and equipment. These are
diluted when used, but will still affect the pH of the final
effluent.
[0015] Most of the water used by breweries leaves in the form of
finished beer, so daily waste water flows are relatively low and
comprise mostly cleaning water. A typical microbrewery may generate
no more than about 200-300 gallons of process waste water per day,
although naturally that volume will grow as production volumes
increase.
[0016] Typical prior art waste water treatment systems are intended
for continuous flow of waste water. However, many manufacturing
processes are operated intermittently, e.g., on a day-night cycle,
wherein there is little or no flow for significant periods of time.
Such a cycle affords an opportunity for a gravity settling
apparatus for removing non-floating solids from a waste water
stream.
[0017] What is needed is an improved method for removing
biologically-digestible solids from food process waste water to
improve waste water quality for discharging into a municipal sewage
system.
[0018] What is further needed is a method for increasing the
percentage of removal of biologically-digestible materials.
SUMMARY OF THE INVENTION
[0019] Current waste water treatment systems maintain a continuous
flow of influent entering a clarification tank. Effluent exits the
clarification tank for secondary treatment. As disclosed in U.S.
Pat. No. 7,972,505, "Primary Equalization Settling Tank", U.S. Pat.
No. 8,225,942, "Self-Cleaning Influent Feed System for a Waste
Water Treatment Plant", U.S. Pat. No. 8,398,864, "Screened Decanter
Assembly", pending U.S. patent application Ser. No. 14/141297,
"Method and Apparatus for a Vertical Lift Decanter System in a
Water Treatment Systems", U.S. patent application Ser. No.
14/142,099, "Floatables and Scum Removal Apparatus", U.S. patent
application Ser. No. 14/325,421, "IFS and Grit Box for Water
Clarification Systems" and U.S. patent application Ser. No.
14/471247 "Method and Apparatus for Using Air Scouring of a Screen
in a Water Treatment Facility", the inventor has developed systems
and processes for primary clarification of the waste water. The
above named applications and patents are incorporated herein by
reference in their entirety for all purposes.
[0020] An improved apparatus and method to treat industrial waste
water is now described in more detail.
[0021] In accordance with apparatus and method of the present
invention, an EPT waste water treatment system includes a sludge
hopper in a lower portion of a clarification, or settling, tank
with an outlet for the sludge. A decanter is provided within the
clarification tank and has an outlet for waste water that passes
through the decanter. The decanter is at an elevation higher than
the sludge hopper and may be equipped to follow vertical changes in
the upper surface of waste water within the clarification tank. The
system includes a pump for supplying waste water influent,
apparatus for dosing the influent, flow control apparatus, and an
influent pipe for delivering waste water influent fluid from the
pump into the clarification tank. The influent pipe is at an
elevation above the sludge outlet and below the decanter. A fluid
deflector, preferably dome-shaped, is provided such that the
influent pipe directs waste water influent against the underside of
the fluid deflector to create mixing of incoming influent with
influent and settled solids already in the clarification tank.
[0022] In operation, in a currently preferred embodiment of the
invention, the operating cycle for the EPT includes mixing the
BOD-rich influent with "seeded" BOD solids that are purposely
retained in the sludge hopper from the previous cycle as the
clarification tank is emptied. The retained BOD sludge solids
typically take the form of a loose concentration of particles of
various sizes and shapes in a layer on the bottom of the tank.
Through turbulent agitation this layer may be dispersed and
re-suspended into the mixing zone below the dome-shaped deflector.
Coalescence of BOD particles occurs in the sludge hopper during
mixing with influent because influent BOD particles adhere to, and
add to, the suspended BOD "seeded" particles when they collide.
[0023] Subsequently, after the tank is full and influent flow is
terminated, there is a settling period as the coalesced BOD settles
to re-form the sludge layer in the hopper section of the EPT. When
the settling period is complete, most but not all of the settled
BOD sludge is drained from the hopper, leaving some of the sludge
layer as "seeding" for the next cycle, while the relative clean
water in the elevated clarification section of the EPT is drawn off
via the vertically-mobile decanter.
[0024] In the present invention, mixing desirably is sufficient
only to keep the sludge layer dispersed and re-suspended into the
mixing zone below the dome. The velocity of influent fluid exiting
the influent pipe is too high to permit settling of small BOD
particles and therefore requires rapid attenuation. The dome-shaped
fluid deflector permits relatively high influent volumes and
velocities to enter the tank by simultaneously attenuating the
influent velocity to a desired lower level and turning the influent
flow outward and downward on a velocity vector shown experimentally
to provide adequate mixing while still allowing settling of BOD in
influent to continue above the deflector.
[0025] In keeping with a design ideal of simplicity and inexpensive
fabrication of an EPT system, mixing in accordance with the present
invention occurs as a result of the static arrangement of system
components, without dynamic mixing. Thus, by controllably and
optimally agitating the sludge layer, such static mixing of
incoming BOD particles with existing sludge is an important element
and discovery in accordance with the present invention.
[0026] Further features and advantages of the present invention
will become apparent to those of ordinary skill in the art in view
of the drawings and detailed description of preferred embodiments
below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The present invention will now be described, by way of
example, with reference to the accompanying drawings, in which:
[0028] FIG. 1 is an elevational cross-sectional view of a portion
of an EPT waste water gravity settling system in accordance with
the present invention; and
[0029] FIG. 2 is an enlarged view of the lower portion of the
system shown in FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0030] Referring now to FIGS. 1 and 2, a system 10 for static
mixing in an industrial waste water settling tank to improve the
recovery of non-floating solids therefrom comprises a tank 12
provided with a sludge hopper 14 in a bottom portion 16 of tank 12
(not to scale). In a currently preferred embodiment, tank 12 is
cylindrical and sludge hopper 14 is conical. A waste water influent
pipe 20 carries waste water and solids into tank 12. The flow of
waste water influent is provided by a pump 21 and is controlled by
flow control apparatus 23 which may include a flow meter and
control valving (not shown) in known fashion. Further, dosing
apparatus 25 may be provided for, e.g., adjusting pH of the
influent or adding coagulants and/or flocculants thereto.
[0031] Preferably, waste water influent pipe 20 comprises an elbow
22 as needed such that waste water and solids 24 are discharged
vertically against a fluid deflector assembly 26. Preferably, fluid
deflector assembly 26 comprises a dome provided preferably with an
inverted distribution cone 28 on its underside, as shown in FIGS. 1
and 2; however, within the scope of the present invention, a fluid
deflector or fluid deflector assembly may take the form of any of
various shapes, with or without cone 28, as may be dictated by a
particular application. Preferably, deflector assembly 26 is
centrally disposed within the space enclosed by sludge hopper
14.
[0032] As described above, the operating cycle for the EPT includes
static mixing of the BOD-rich influent with "seeded" BOD sludge
remaining in the sludge hopper from the previous cycle. Preferably,
the sludge layer comprises significant amounts of flocculants
and/or coagulants that assist in coalescing the influent BOD
particles with the "seeded" BOD.
[0033] In operation, fluid deflector assembly 26 slows the influent
flow velocity of waste water 24 and redirects it generally outward
and downward in a circular pattern toward the walls of sludge
hopper 14 to facilitate the mixing and settling of solids out of
the waste water. As the fluid level in tank 12 rises and solids
begin to settle out of the waste water in sludge hopper 14,
coalescence occurs during mixing of influent 24 with material
already in sludge hopper 14 because BOD particles tend to coalesce
with the "seeded" BOD particles suspended by turbulent agitation
from the influent flow. Subsequently, during a quiescent settling
period after influent flow is terminated, the BOD coalescent sinks
into the hopper section of the EPT. When the settling period is
complete, most of the settled BOD is drained from the hopper,
leaving some BOD as "seeds" for the next cycle, while the
relatively clean water in the elevated clarification section of the
EPT is drawn off via the decanter (not shown).
[0034] It is an important feature of the present invention that the
separation percentage of BOD particles in influent waste water
entering the tank is increased by a method that impinges such
particles on other BOD materials such as but not limited to BOD
particles already present therein, causing coalescence thereof into
larger particles having greater settling tendency to form a new
layer of BOD materials. In the present invention, such impingement
is conferred by controlling the influent flow rate in combination
with the arrangement of fixed deflector and tank components.
[0035] System 10 has been modeled using computer simulation to
identify the critical parameters of the design and to establish
optimum values for mixing. The simulation indicates that the dome
and inverted cone assembly provides the most effective mixing
geometry.
[0036] Calculations were performed on a system 12 having the
following dimensions:
[0037] Dome diameter: 15 inches
[0038] Dome height: 6 inches
[0039] Cylindrical EPT tank inside diameter: 48 inches
[0040] Inverted cone within the dome: 5-inch width and 1.5-inch
height.
[0041] The included cone angle at the bottom of sludge hopper 14
was 60.degree.. The lower rim of the dome was located approximately
12 inches above the bottom 15 of the sludge hopper.
[0042] For this configuration, with a 2-inch diameter influent pipe
20 and influent flow rate of about 80 gpm, optimum mixing under
these aforementioned conditions was found to occur when the spacing
between upper end 30 of influent pipe 20 and inverted cone 28 was 5
inches.
[0043] A wide range of dome deflector and inverted cone dimensions
have been shown to provide adequate mixing for a variety of sizes
of EPT tank and influent flows. For example, inverted cone 28 need
be only as wide as the impinging flow which to a good approximation
is equal to the inside diameter of upward directed influent pipe
20. Inverted cone 28 preferably has an aspect ratio (height/width)
of at least 0.2 to redirect effectively the vertical flow from the
influent pipe to radial flow along the underside of dome 26. Cone
28 may be fluted where it meets the underside of dome 26 to avoid
an abrupt change in fluid direction and thus smooth fluid flow.
[0044] A critical factor is the fluid velocity of influent liquid
24 which for good mixing should impinge on the dome assembly at a
velocity between about 2 fps and about 15 fps, with an optimal
velocity of about 6 fps (i.e., 2 meters/second).
[0045] As flow varies with the square of the pipe ID, an increase
in the influent pipe diameter from 2 inches to 4 inches would
increase flow about four-fold, e.g., to 320 gpm to maintain a 6 fps
influent velocity. As flow also scales linearly with the influent
velocity for a given pipe diameter, reducing influent flow velocity
to 3 fps would reduce the flow rate by half.
[0046] Fluid exiting influent pipe 20 is redirected by dome 26
radially outward along the underside of the dome as discussed
above.
[0047] The space between lip of the influent pipe and the inverted
cone defines a virtual cylinder with the diameter equal to that of
the influent pipe and a height equal to the spacing between the
pipe and the inverted cone. Since by the conservation of volume all
the influent must pass through the sides of this virtual cylinder,
the cylinder must have a surface area A.sub.c equal to or greater
than the cross sectional area of the influent pipe A.sub.p so as
not to impede the flow (A.sub.c.gtoreq.A.sub.p). The surface area
A.sub.c of the cylinder is 2R.PI.H where R is the influent pipe
inner radius and H is the spacing of the lip of the influent pipe
to the inverted cone. This area must be equal to or greater than
the cross sectional area of the influent pipe .PI.R.sup.2, e.g.,
2R.PI.H.gtoreq..PI.R.sup.2. Therefore, H=R/2, and thus the minimum
spacing between the lip and the inverted cone is equal to at least
one-half the inner radius of the influent pipe.
[0048] The fluid stream 24 from influent pipe 20 into tank 12 will
slow and dissipate as it progresses towards inverted cone 28. The
maximum spacing between the lip of the influent pipe and the
inverted cone is determined by the requirement that the upward
velocity of the fluid impinging on the inverted cone be at least 4
feet/second so the fluid has sufficient momentum to promote good
mixing within the fluid dynamic streams predicted by computer
simulations.
[0049] To function effectively, the dome generically need be only
an upward convexity defining an upward concavity on its underside;
it need not be spherical or parabolic. The dome serves two
functions: a) to create flow channels sideways and downwards to
promote good mixing; and b) to contain the highest velocity flow
channels to stay beneath the dome elevation within the tank,
allowing the fluid zone in the tank above the dome to be relatively
tranquil to minimize movement of sludge flocs into the upper
portion of the tank and thus increase the time needed for settling.
The diameter of the dome and its specific shape are established by
the requirement that the fluid velocity preferably is less than
about 1 ft/second at the outer edge of the dome. Higher velocities
can push some of the suspended BOD seed particles in the influent
into the upper portion of the tank, thus inhibiting coalescence and
settling of BOD particles.
[0050] Various changes may be made to the structure embodying the
principles of the invention. The foregoing embodiments are set
forth in an illustrative and not in a limiting sense. The scope of
the invention is defined by the claims appended hereto.
* * * * *