U.S. patent application number 09/978473 was filed with the patent office on 2002-02-28 for wastewater treatment tank with influent gates and pre-react zone with an outwardly flared lower portion.
Invention is credited to Lindbo, Glen D..
Application Number | 20020023868 09/978473 |
Document ID | / |
Family ID | 22288577 |
Filed Date | 2002-02-28 |
United States Patent
Application |
20020023868 |
Kind Code |
A1 |
Lindbo, Glen D. |
February 28, 2002 |
Wastewater treatment tank with influent gates and pre-react zone
with an outwardly flared lower portion
Abstract
A wastewater treatment tank with influent gates (24) and
pre-react zone with an outwardly flared lower portion. Influent
passes over influent gates (24), which introduce turbulence,
causing aeration, and reducing flow velocity. As influent flows out
of the influent gate housing (20), flow velocity is further reduced
by contact with the surface of the wastewater in the basin and
influent flow is directed laterally by an influent gate bottom
(30). A pre-react zone director (34) spaced apart from the bottom
(42) of the basin encloses the influent gate housing (20) and
utilizes an outwardly flared lower portion, or flap (38), to
further reduce flow velocity and enhance laminar flow. This results
in minimal disturbance of settled sludge blanket, allowing it to
act as a natural biological filter, which in turn results in a
superior supernatant.
Inventors: |
Lindbo, Glen D.; (Honolulu,
HI) |
Correspondence
Address: |
Martin E. Hsia
P. O. Box 939
Honolulu
HI
96808-0939
US
|
Family ID: |
22288577 |
Appl. No.: |
09/978473 |
Filed: |
October 15, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09978473 |
Oct 15, 2001 |
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09445997 |
Dec 16, 1999 |
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6303026 |
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09445997 |
Dec 16, 1999 |
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PCT/US99/22602 |
Sep 28, 1999 |
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60102187 |
Sep 28, 1998 |
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Current U.S.
Class: |
210/198.1 ;
210/117 |
Current CPC
Class: |
C02F 2301/024 20130101;
C02F 2209/44 20130101; Y02W 10/10 20150501; C02F 3/1242 20130101;
C02F 3/301 20130101; C02F 3/02 20130101; C02F 1/006 20130101; Y02W
10/15 20150501; C02F 2301/022 20130101; C02F 3/30 20130101; C02F
2209/42 20130101 |
Class at
Publication: |
210/198.1 ;
210/117 |
International
Class: |
B01J 020/00 |
Claims
What is claimed is:
1. A device to treat influent, comprising: a basin having a bottom;
an influent gate housing having a bottom portion mounted in said
basin to receive said influent; influent gates mounted inside said
influent gate housing, whereby said influent flows over said
influent gates and said influent gates create turbulent flow and
aeration in said influent, and reduce flow velocity of said
influent; an influent gate bottom mounted in said basin under said
influent gate housing, whereby influent exiting said bottom portion
of said influent gate housing is directed laterally; and a
pre-react zone director having a lower portion at least partially
enclosing said influent gate housing, said pre-react zone director
defining a main react zone inside said basin, but outside said
pre-react zone director, wherein said lower portion of said
pre-react zone director is spaced apart from said bottom of said
basin and defines a contact zone between said lower portion and
said bottom, whereby said pre-react zone director decreases
influent flow velocity and directs flow of said influent in a
laminar fashion through said contact zone and into said main react
zone; whereby said influent avoids disturbing any settling sludge
in said main react zone and forms a supernatant by filtering
through said settling sludge; and whereby settling, aerobic
processing, anaerobic processing, and filtering are all performed
in a single basin.
2. A device according to claim 1, wherein said influent gates are
downwardly angled at between 90 and 180 degrees.
3. A device according to claim 1, wherein said influent gates are
spaced apart from each other and mounted on alternating sides of
said influent gate housing.
4. A device according to claim 1, wherein said influent gate bottom
comprises a "T" fitting having a single port.
5. A device according to claim 1, wherein said influent gate bottom
comprises a "T" fitting having more than one port.
6. A device according to claim 1, wherein said bottom portion of
said influent gate housing comprises a 90 degree lateral lip
extending completely around said influent gate housing.
7. A device according to claim 1, wherein said influent gate bottom
further comprises a disc mounted below, and spaced apart from, said
influent gate housing.
8. A device according to claim 1, wherein said pre-react zone
director completely encloses said influent gate housing.
9. A device according to claim 1, wherein said lower portion of
said pre-react zone director comprises a flap, wherein said flap is
an angled lip extending around the perimeter of the base of said
pre-react zone director.
10. A device according to claim 9, wherein said flap is downwardly
angled, whereby said influent is directed in a downward and outward
manner through said contact zone and into said settling sludge so
as to maximize contact of said influent with said settling
sludge.
11. A device according to claim 1, wherein said pre-react zone
director has an outwardly flared lower portion.
Description
TECHNICAL FIELD
[0001] This invention relates to a wastewater treatment tank with
influent gates (to create turbulent flow and reduce influent flow
velocity) and a pre-react zone director having an outwardly flared
lower portion. The pre-react zone director causes laminar flow of
influent below a settling blanket of sludge to avoid disturbing the
blanket, thus allowing the blanket to function as a filter and
resulting in a clearer supernatant than in conventional tanks.
[0002] Wastewater treatment facilities play an important role in
society. As urban and rural populations continue to grow, however,
these facilities become increasingly overtaxed and unable to meet
the demands placed upon them. These increased demands cause many
current wastewater treatment plants to operate near or at capacity.
In addition, many treatment facilities were originally constructed
decades ago, and utilize technology that is currently failing.
Failing or inadequate treatment facilities pose an environmental
concern, especially in light of increasingly stringent municipal,
state, and federal environmental standards.
[0003] Due to the odious nature of wastewater treatment facilities,
these facilities have often been constructed far from the sources
of sewage to minimize exposure to populated areas. As a result,
long sewage lines are needed to connect treatment plants to sewage
sources. However, the acidic, corrosive and septic nature of
wastewater, including hydrogen sulfide gas, which naturally occurs
during the wastewater treatment process, causes the breakdown and
failure of long sewage pipes
[0004] To alleviate these problems, many areas have undertaken to
either construct more treatment facilities, or to increase the
efficiency of existing facilities. The construction of new
facilities, however, may be blocked by those who fear the negative
impact of such a facility in close proximity to urban or rural
areas, such as the emanation of offensive odors, and the potential
risk of untreated wastewater spillage. Increasing the efficiency of
existing plants can come at great cost, and also poses the risk of
interrupting current service.
[0005] In order to increase efficiency, and to lower consumer
costs, many areas have privatized wastewater services. However,
like any business, these private wastewater plants must be
economically viable, and are faced with maintenance, energy, and
other costs, which reduce profits and impede business growth.
[0006] Rapid development and population growth of third world
countries also pose a significant sanitation and health risk, as
wastewater needs cannot be met by current services. Therefore,
these areas are especially in need of low cost, highly efficient
wastewater treatment plants.
BACKGROUND ART
[0007] U.S. Pat. No. 5,302,289 to McClung, et al., discloses a
wastewater treatment facility having an inlet in which there are a
plurality of downwardly angled structures in a downcomer.
[0008] U.S. Pat. No. 4,230,570 to Irving discloses an aerator
having an inlet having a downward and outward direction at the
bottom, and adjacent inlet air provided by a manifold.
[0009] U.S. Pat. No. 5,051,213 to Weske discloses a method and
apparatus for mixing fluids, which includes tines that are adjacent
to gas inlets.
[0010] U.S. Pat. No. 4,162,971 to Zlokarnik, et al., discloses the
use of deflecting elements to mix liquids and gas.
[0011] U.S. Pat. No. 4,081,368 to Block, et al., discloses the use
of staggered partitions in treating wastewater.
[0012] U.S. Pat. No. 4,505,820 to Eertink discloses the use of
multiple separate bioreactors in treating wastewater.
[0013] U.S. Pat. No. 4,705,634 to Reimann, et al., discloses the
mixing of wastewater and activated sludge in the presence of
carrier particles for microorganisms.
[0014] U.S. Pat. No. 4,136,023 to Kirk, et al., discloses an
apparatus for wastewater treatment in which oxygenated wastewater
is directed out through an adjustable flap.
[0015] U.S. Pat. No. 5,688,400 to Baxter, Sr. discloses a waste
liquid treatment plant, which includes aeration for downwardly
flowing liquid, air nozzles, and a conical section.
[0016] U.S. Pat. No. 3,804,255 to Speece discloses a recycling gas
contact apparatus for waste material, which includes a downflow
conducting cone member and bubble injector.
[0017] U.S. Pat. No. 4,421,648 to Besik discloses a single reaction
tank in a single suspended growth sludge system that includes a
conical shaped outlet section.
[0018] U.S. Pat. No. 4,452,701 to Garrett, et al., discloses an
open-bottomed stilling chamber above an open-topped chamber with a
conical outlet.
[0019] It is therefore an object of this invention to provide
methods and apparatus for a wastewater treatment system, having
influent gates and pre-react zone with outwardly flared lower
portion to achieve tertiary treatment results (at least in certain
fields of use) from a secondary treatment facility using a single
tank. In this connection, primary treatment is usually understood
to include settling and anaerobic processes, secondary treatment is
usually understood to include aerobic processes, and tertiary
treatment is usually understood to include filtering.
[0020] It is a still further object of this invention to provide
methods and apparatus for low-cost, high-efficiency wastewater
treatment systems.
[0021] It is a still further object of this invention to provide a
process and apparatus that substantially reduces production of
sewage sludge.
[0022] It is a still further object of this invention to provide a
process and apparatus that reduces energy consumption by reducing
the number of pumps and blowers needed for operation.
[0023] It is a still further object of this invention to provide an
apparatus with minimal moving parts.
[0024] It is a still further object of this invention to provide
such methods and apparatus that combines processes to eliminate the
need for multiple stage components, thereby eliminating the odors,
maintenance and land requirements, and other costs associated with
multi-stage complex wastewater systems.
[0025] It is a still further object of this invention to provide
methods and apparatus resulting in more nutrient and chemical
removal than previous wastewater systems.
[0026] It is a still further object of this invention to provide
methods and apparatus which is simple in construction and operation
so that malfunctions can be easily and quickly diagnosed to reduce
the costs of repair and maintenance.
[0027] It is a still further object of this invention to provide
methods and apparatus that are scalable so that multiple smaller
decentralized plants can be used instead of large centralized
plants with long pipelines, which allows geographic dispersal of
such plants and reduction of peak flows of effluent in particular
areas.
[0028] It is a still further object of this invention to provide
methods and apparatus that allow plants of particular capacity to
be constructed using up to 50% less land.
[0029] It is a still further object of this invention to provide
methods and apparatus that can be operated with less manpower.
[0030] It is a still further object of this invention to provide
methods and apparatus that allow multiple modular plants with
continuous influent flow and intermittent decanting to allow the
environment to recover between decants, and allows multiple
staggered decanting so that common effluent facilities need only
have the capacity to handle one or two (or more, but less than all)
modules at a time.
[0031] It is a still further object of this invention to provide
methods and apparatus that can be easily retrofittable to existing
properly sized basins.
[0032] It is a still further object of this invention to provide
methods and apparatus that denitrify the system by both aerobic and
anaerobic processes to avoid algae blooms.
DISCLOSURE OF INVENTION
[0033] These and other objects are achieved by a device to treat
influent that includes a basin with an influent gate housing in the
basin to receive influent. Influent gates are mounted inside the
influent gate housing so that influent flows over the influent
gates, creating turbulent flow and aeration in the influent, and
reducing flow velocity of the influent. An influent gate bottom is
mounted in the basin under the influent gate housing so that
influent exiting the bottom portion of the influent gate housing is
directed laterally. A pre-react zone director having an outwardly
flared lower portion is mounted to the basin and at least partially
encloses the influent gate housing. The pre-react zone director
defines a main react zone inside the basin, but outside the
pre-react zone director, and the lower portion of the pre-react
zone director is spaced apart from the bottom of the basin and
defines a contact zone between the lower portion and the bottom of
the basin. The pre-react zone director decreases influent flow
velocity and directs flow of said influent in a laminar fashion
through the contact zone and into the main react zone, so that the
influent avoids disturbing any settled sludge in the main react
zone and allows formation of a supernatant. The influent does not
disturb the settled sludge and is filtered through the sludge
(which acts as a biological filter) before forming the supernatant,
so that the supernatant is comparable to filtered supernatant.
Thus, settling (the settling sludge blanket), aerobic processing
(passing the supernatant over the gates), anaerobic processing (the
biological activity in the settling sludge blanket) and filtering
(passing the influent through the settling sludge blanket to form
the supernatant) are all performed in a single basin.
[0034] This invention substantially reduces sewage sludge
production and energy consumption by wastewater treatment systems,
by utilizing a non-mechanical process that uses fewer pumps and
blowers than a conventional wastewater treatment system, and
utilizes a minimum of moving parts. It reduces plant size, and
therefore reduces land requirements, by up to approximately 50%
from that of conventional wastewater treatment facilities, and
requires only approximately 6 months to 1 year of design and
construction time. This invention also requires less manpower and
maintenance due to fewer components.
[0035] Furthermore, as the use of septic tanks is being restricted
by state and municipal regulations, affecting both residential and
commercial properties, this invention allows for a septic tank
replacement, without having to expend time and money to connect
these properties to a large centralized system, or to construct an
entirely new sewage infrastructure. This is particularly
advantageous for remote small scale commercial developments.
[0036] This invention therefore allows the construction of smaller
plants closer to the sources of sewage, resulting in shorter sewage
pipes, which allow a shorter resident time of influent within the
pipes, and therefore significantly reduces exposure to sewage and
the possibility of failure.
[0037] This invention allows a continuous sewage influent flow into
a single basin wastewater treatment system. The modular nature of
the invention allows multiple basins to be used, thus allowing
multiple staggered decanting so that effluent facilities can be
shared and do not have to be as large as conventional ones. This
intermittent decanting allows the environment to recover between
decanting.
[0038] The influent flow travels over the influent gates, creating
turbulence in the flow and reducing downward flow velocity. The
resulting turbulent flow allows air, in the form of minute bubbles,
to be mixed into the influent stream, which starts aerating the
influent flow. These minute bubbles also cause a reversing action
of the influent flow upon contact with the surface of the
wastewater in the basin. This reversing action reduces downward
velocities, and thus works in conjunction with the influent gates.
The exit of the influent gate housing is below the level of
wastewater in the basin.
[0039] There are preferably one or more influent gates located
within the influent gate housing. These gates are preferably
located above the lowest normal wastewater level within the basin.
To utilize their turbulent flow/aeration properties, however, gates
may also be placed below the wastewater level if further flow
velocity reduction is required. Although utilizing no gates falls
within the operable range of the invention, it is preferable to
have at least one gate. Optimally, there should be more than one
gate installed to achieve the best quality effluent.
[0040] The influent gates are strategically spaced with the first
gate preferably placed approximately one diameter down the vertical
influent riser from the influent intake. The first gate is
optimally placed approximately where the influent would first hit
the wall of the influent gate housing on the side opposite the
incoming influent flow. Subsequent gates would preferably be
mounted on alternating sides of the interior of the influent gate
housing. The flow will thus have a horizontal backward/forward
motion as it travels vertically down the riser portion of the
influent gate housing (the influent riser). Although it is within
the operable range of this invention to have the gates placed in
many other positions within the influent gate housing, the gates
should preferably be placed in a zig-zag manner down the vertical
influent riser, spaced apart from each other by approximately the
diameter (or width) of the riser. Enough gates should be provided
so that the lowest gate is above the lowest wastewater level
(bottom water level) expected during normal operation.
[0041] It falls within the operable range of the invention for each
gate to be aligned at a downward angle between 90 and 180 degrees
from the plane of the influent gate housing wall. However, the
greater the angle, the greater the likelihood of un-screened debris
within the influent stream getting caught on the gate. Therefore,
preferably, the gates should be at a downward angle greater than 90
degrees from the plane of the influent gate housing wall.
Optimally, the gates should be at a downward angle between 120 and
135 degrees from the plane of the influent gate housing wall.
[0042] After flow velocities are reduced utilizing the influent
gates, the influent stream then flows through the basin in a
laminar fashion via an outwardly flared portion of the pre-react
zone, as described below. As the stream flows to the bottom of the
vertical riser portion of the influent gate housing, the stream
encounters the floor, or bottom fitting, which is designed to stop
downward flow velocities. This bottom fitting is preferably placed
at a level below the lowest normal wastewater level in the basin
(brought about by normal hydraulic equalization of the entire
basin). When the influent flow reaches the surface of the
wastewater, splashing further reduces the influent flow
velocity.
[0043] The bottom fitting is preferably a standard "T" fitting
affixed to the base of the vertical riser portion of the influent
gate housing. This "T" fitting is preferably of a multi-port
design, having two openings to direct the influent flow in a
lateral direction, however, it is within the operable range of the
invention to have more or less openings.
[0044] Alternatively, it is within the operable range of the
invention if there were no bottom "T" fitting affixed to the bottom
of the vertical riser portion of the influent gate housing. In
order to achieve downward flow velocity reduction, a disc or
platform may be supported above the floor of the basin, preferably
with a peg or some other support, directly below the bottom opening
of the influent gate housing. In this alternative design form, flow
behavior would not change significantly. As discussed above, the
influent flow would travel through the vertical riser portion of
the influent gate housing, encountering the influent gates, which
create turbulent flow and reduce downward flow velocity. Upon
contact with the surface of the wastewater, which is above the
bottom exit of the influent gate housing, both splash energy and
the reversing action of the turbulent flow further reduce downward
flow velocity. As the flow continues downward after contact with
the surface, it encounters the disc or platform, which then
omni-directionally directs flow laterally, as opposed to a "T"
fitting, which directs flow laterally through ports.
[0045] If no bottom fitting is utilized, then the base of the
vertical riser portion of the influent gate housing would
preferably have a 90 degree lip extending 360 degrees around the
bottom exit of the influent gate housing. This lip would act as an
upward ceiling to assist in directing the flow laterally. It is
within the operable range of the invention to have no lip, but such
a lip is preferred to enhance lateral flow out of the influent gate
housing. If there are multiple influent gate housings within the
pre-react zone director, then the surface of the disc or platform
preferably extends to cover the entire opening area of the
pre-react zone director. It is within the operable range of the
invention for the disc or platform to be in any geometric shape,
however, if only one influent gate housing is utilized, it is
preferable that the disc or platform be the same shape as the base
of the influent gate housing. If multiple influent gate housings
are utilized within a single pre-react zone director, then the disc
or platform should preferably be the same shape as the base of the
pre-react zone director.
[0046] After the influent flow undergoes turbulent aeration and
velocity reduction in the influent gate housing, influent velocity
is reduced further and then directed via the pre-react zone
director into the main react zone of the basin for treatment. The
pre-react zone director is designed such that one or more walls
create a chamber that separates initial influent flows from the
rest of the influent within the basin. This prevents the initial
influent flow from mixing with and disturbing the main react zone's
settled biomass during the settle and decant phases of operation.
This allows optimal operation of the settled sludge blanket
(biomass) as a natural biological filter.
[0047] The pre-react zone director utilizes a flap at its base to
direct the flow in a laminar fashion into the main react zone. As a
result, disturbances of the settled sludge blanket are minimized,
thus creating a dense natural biological filter (biomass), which
absorbs biological nutrients and chemicals from the influent sewage
stream during the settle phases of operation, and thus creating a
superior supernatant for decant. Furthermore, the downward and
outward direction of the influent allows increased contact between
the influent and resulting biomass, which in turn results in more
nutrient and chemical removal than previous systems.
[0048] It is within the operable range of the invention if the
pre-react zone director utilizes any geometric shape, however, it
should preferably be either rectangular, square, triangular, or
circular to facilitate installation of the flap. The pre-react zone
director is preferably affixed to the side of the main basin wall
opposite the decanter, and situated in the center of the main
basin's width. It is within the operable range of the invention if
the pre-react zone director is suspended in the basin via flotation
devices and anchored in some manner, however, it is preferable that
the pre-react zone director be affixed and mounted to the basin
wall for structural support and aesthetics. Optimally, the
pre-react zone director should be mounted on posts, affixed to the
basin wall opposite the decanter, in the middle of the basin width,
with the posts being affixed to either the bottom or top of the
basin. Where this optimal configuration is difficult (such as with
fiberglass basins, or basins in which the wall opposite the
decanter is curved or otherwise irregularly shaped), it is then
preferable to have the pre-react zone director affixed to the top
of the basin, or mounted on posts, which are affixed to the bottom
of the basin.
[0049] The pre-react zone director flap is an angled lip that
extends around the entire perimeter of the base of the pre-react
zone director. It is within the operable range of the invention
that the flap be aligned at an outward angle between 0 and 180
degrees from the plane of the pre-react zone director wall. The
flap should preferably be aligned at an outward angle of greater
than 90 degrees from the plane of the pre-react zone director wall.
Optimally, the flap should be aligned at a down and outward angle
of 120 to 135 degrees from the plane of the pre-react zone director
wall. This optimal angle alignment allows for optimum laminar flow
of the influent into the main react zone.
[0050] It is within the operable range of the invention if the
leading edge of the flap where the flap is connected to the base of
the pre-react zone director is jagged or uneven. However, the
leading edge should preferably be square. Optimally, the edge
should be rounded to allow optimum laminar flow of the influent,
and decrease turbulent flow under the flap. In addition to reducing
turbulence and creating laminar flows, the flap also adds
structural strength to the pre-react zone director. It has been
found that other systems utilizing a react zone need eventual
replacement of the react zone walls because those walls tend to
fail after continuous flexing caused by turbulent flow during the
aeration phases of operation. By reducing this turbulence, the flap
reduces the stresses on the pre-react zone director walls, and
extends the structural longevity of the pre-react zone
director.
[0051] The pre-react zone director encloses the influent gate
housing(s) within the basin. Because it rests above the floor of
the basin, there is a submerged gap between the flap and the basin
floor. This gap comprises the contact zone, where the initial
influent flow exits the pre-react zone director and comes into
contact with the settled sludge blanket within the main react zone.
It is within the operable range of the invention if the pre-react
zone director comprises a single wall stretching the width of the
basin, thereby creating a 180 degree enclosure of the influent gate
housing. This thereby creates a 180 degree contact zone, which is
within the operable range of the invention. The pre-react zone
director should preferably surround the influent gate housing with
a minimum of 270 degrees of enclosure, creating a preferred 270
degree contact zone. It is optimal for the pre-react zone director
to completely surround the influent gate housing with a 360 degree
enclosure, which allows for an optimal 360 degree contact zone, and
which makes optimum usage of the biological filter in the settled
sludge blanket.
[0052] This device eliminates the need for a separate clarifier,
aeration basin, and settling basin, as this invention combines all
these elements within one basin. The simplicity of this invention
thus eliminates the odors, maintenance, land requirements, and
other costs associated with other multi-basin complex wastewater
systems. Furthermore, aeration basins for other technologies
typically are larger than the clarifiers associated with them. This
invention allows the basin to act as a unified clarifier and
aeration basin during the cyclic aeration cycle, thus achieving the
clarification in a basin that is the same size as the aeration
basin. This eliminates the need for separate basins, and
substantially reduces the need for sludge return lines, and their
associated costs.
BRIEF DESCRIPTION OF DRAWINGS
[0053] FIG. 1 is a side elevational cutaway view of a presently
preferred embodiment of the present invention.
[0054] FIG. 2 is a schematic diagram of an alternative embodiment
of FIG. 1 and includes an optional platform or disk at the base of
the influent gate housing.
[0055] FIG. 3 is top plan view of the embodiment of FIG. 1.
[0056] FIG. 4 is a side elevational cutaway view of the influent
gate housing.
[0057] FIG. 5 is a partial side elevational view of the pre-react
zone director flap.
[0058] FIG. 6 is a top elevational view of the influent gate
housing and basin of the presently preferred embodiment of the
present invention.
[0059] FIG. 7 is a top elevational view of the influent gate
housing and basin of the alternative embodiment of FIG. 2, whereby
the pre-react zone director surrounds 180 degrees around the
influent gate housing.
[0060] FIG. 8 is a side elevational cutaway view of a presently
preferred decanter according to the present invention.
[0061] FIG. 9 is an end elevational cutaway view of the decanter of
FIG. 8.
BEST MODES FOR CARRYING OUT INVENTION
[0062] The presently preferred best modes for carrying out the
present invention are illustrated by way of example in FIGS. 1 to
7.
[0063] Referring to FIG. 1, shown is a presently preferred
embodiment of the present invention. The invention comprises the
influent gate housing 20, influent gates 24, influent gate bottom
30, and pre-react zone director 34 with flap 38, within a single
basin 42. The air diffusers 46, float tree 48, decanter 50, and
emergency overflow 52 are standard components of a wastewater
treatment basin, and it is well within the skill of a person of
ordinary skill in the art to select and install these
components.
[0064] The influent gate housing 20 comprises a vertical riser
portion 21, an opening 22 at the top of the vertical riser portion
21, influent gates 24, and an influent gate bottom 30. Preferably,
the components of the influent gate housing 20 should be made of
any product that is non-corrosive in the particular wastewater
stream that is being treated, such as PVC, fiberglass, lined
(sealed) concrete, and stainless steel, but is not limited to these
materials. Preferably, the vertical riser portion 21 of the
influent gate housing 20 is a cylindrical pipe. Because normal
operations of influent stream usually have an air pocket at the top
of the vertical riser portion 21, it is within the operable range
of the invention to have no opening 22. However, it is preferable
to have, at a minimum, a removable cover, that can be removed for
cleaning, maintenance, or inspection purposes. Optimally, there
should merely be an opening 22 for aeration, ease of cleaning, and
maintenance inspections (FIG. 4).
[0065] In normal operations, influent stream enters the basin via
the influent gate housing 20. The influent flow travels vertically
downward over the influent gates 24. The influent gates 24 act as
baffles within the vertical riser 21 and create turbulence within
the influent stream that aerates the influent flow. The influent
gates 24 preferably comprise non-corrosive material that is
appropriate for the particular wastewater being treated, such as
PVC, fiberglass, and stainless steel, but is not limited to these
materials.
[0066] Each influent gate 24 is preferably set at a downward angle
greater than 90 degrees from the plane of the influent gate housing
20. Optimally, the influent gates 24 should be at a downward angle
between 120 and 135 degrees from the plane of the influent gate
housing 20 (FIG. 4). Each influent gate 24 is affixed to the
vertical riser portion 21 of the influent gate housing 20 as shown
in FIG. 4. Preferably, each influent gate 24 is affixed by being
placed in a slot within the vertical riser 21, with each slot being
sealed, preferably with a rubber seal or glue (but not limited to
such means) to keep the influent gate 24 in place, and to prevent
influent from leaking outside the influent gate housing 20.
Affixing the influent gates 24 in such a manner allows the influent
gates 24 to be removed for replacement, or angle adjustment if
deemed necessary.
[0067] Preferably, each influent gate 24 will have a bulb or bump
26 affixed to the end of the influent gate 24 that is on the
exterior side of the influent gate housing 20. This bulb 26
prevents the influent gate 24 from sliding into the interior of the
influent gate housing 20, and in conjunction with said rubber seal
or glue, holds the influent gate 24 in place.
[0068] Alternatively, the influent gate 24 may be installed and
affixed to the influent gate housing 20 with a hinge and a spring
mechanism 28 may be affixed on the underside of the influent gate
24, connected to the influent gate housing 20, as shown in FIG. 4.
This will allow the influent gate 24 to open completely in the
event that debris or some other material becomes clogged within the
vertical riser portion 21 of the influent gate housing 20.
[0069] Although the number of influent gates 24 installed within
the influent gate housing 20 may vary according to the needs of the
particular wastewater system, it is preferable to have at least one
influent gate 24 installed within the influent gate housing 20.
Although it is within the operable range of the invention to have
no influent gates 24, optimally, more than one influent gate 24
should be installed to achieve the best quality effluent.
Preferably, each influent gate should be placed in an alternating
pattern, equally spaced apart and extending at least halfway down
the side of the vertical riser portion 21 of the influent gate
housing 20, as shown in FIGS. 1, 2 and 4. Optimally, the topmost
influent gate 24 should be positioned on the side of the vertical
riser 21 opposite the initial influent flow, as shown in FIGS. 1
and 2. Each influent gate 24 thereafter would preferably be placed
in an alternating pattern, equally spaced down the vertical riser
21.
[0070] In normal operations, after the influent flow travels over
the influent gates 24, the influent flow then exits the vertical
riser portion 21 of the influent gate housing 20. Preferably, there
is a influent gate housing bottom 30 affixed to the bottom end of
the vertical riser portion 21, preferably comprising a multi-ported
"T" pipe fitting, as shown in FIG. 1. Preferably, the "T" fitting
should have two openings. However, it is within the operable range
of the invention to have more or less openings, to accommodate the
particular wastewater system in operation.
[0071] Referring to FIG. 2, shown is an alternative embodiment in
which, instead of a "T" fitting, the influent gate housing bottom
has a 90 degree lateral lip extending at least partially (but
preferably completely) around the bottom edge of the vertical riser
portion 21 of the influent gate housing, and a disc or platform 41
supported above the bottom of the basin via a peg or some other
vertical support affixed to the bottom of the basin. Preferably,
the surface of disc or platform 41 should be co-extensive with the
bottom opening of the influent gate housing 20. Preferably, the
shape of the disc or platform 41 should be the same as the shape of
the bottom of the influent gate housing.
[0072] The pre-react zone director 34 comprises one or more walls
surrounding the influent gate housing 20 to create a chamber that
separates initial influent flows from the rest of the flow within
the basin 42, as shown in FIGS. 1, 2, 6, and 7. Preferably, the
pre-react zone director is any geometric shape that allows an
outwardly directed flap 38 to be affixed to the bottom edge of the
pre-react zone director 34. Such geometric shapes include a
rectangular, square, triangular, or circular shape, but is not
limited to these shapes. It is within the operable range of the
invention if the pre-react zone director 34 comprises a single wall
stretching the width of the basin, thereby creating a 180 degree
enclosure of the influent gate housing 20, as shown in FIG. 6. The
pre-react zone director 34 should preferably surround the influent
gate housing 20 with a minimum of 270 degrees of enclosure, as
shown in FIG. 3. It is optimal for the pre-react zone director 34
to completely surround the influent gate housing 20 with a 360
degree enclosure, as shown in FIG. 7.
[0073] The pre-react zone director 34 is preferably affixed to the
side of the main basin wall 43 opposite the decanter 50, and
situated in the center of the main basin wall's width. It is within
the operable range of the invention if the pre-react zone director
34 is suspended in the basin 42 via flotation devices and anchored
in some manner, however, it is preferable that the pre-react zone
director 34 be affixed and mounted to the basin wall 43. Optimally,
the pre-react zone director 34 should be mounted on posts, affixed
to the basin wall 43 opposite the decanter 50, in the middle of the
basin wall's width, with the posts being affixed to either the
bottom or top of the basin 42.
[0074] The pre-react zone director 34 preferably comprises a flap
38, which is an angled lip that extends around the entire perimeter
of the base of the pre-react zone director 34, as shown in FIGS. 1,
2, and 3. It is within the operable range of the invention that the
flap 38 angled outwardly between 0 and 180 degrees from the plane
of the pre-react zone director 34 wall. The flap 38 should
preferably be angled outwardly greater than 90 degrees from the
plane of the pre-react zone director 34 wall. Optimally, the flap
38 should be aligned downwardly and outwardly at 120 to 135 degrees
from the plane of the pre-react zone director 34 wall, as shown in
FIG. 5.
[0075] It is within the operable range of the invention if the
leading edge 40 of the flap 38 is jagged or uneven. However, the
leading edge 40 should preferably be square. Optimally, the leading
edge 40 should be rounded. The trailing edge of the flap 38 may
comprise a straight edge, or a rounded edge.
[0076] The overall operation of the present invention will now be
described. The influent continuously flows into the influent gate
housing 20 and strikes the topmost of the gates 24. The velocity of
the influent is reduced as it cascades through the remaining gates
24 and reaches the bottom of the influent gate housing 20. The
influent meets the surface of the wastewater before it reaches the
bottom of the influent gate housing, and its velocity is thereby
further reduced. The influent is then directed laterally by the
influent gate bottom 30 (or the platform or disk in an alternative
embodiment). The influent then travels downwardly through the
pre-react zone director 34 until it reaches the pre-react zone
director flap 38. The space between the bottom of the basin 42 and
the pre-react zone director flap 38 is the contact zone, and the
influent is constrained by the pre-react zone director flap (and
other structural features of the invention) to flow through the
contact zone in a laminar fashion. Because the influent flows
laminarly, it avoids disturbing the settling sludge blanket. Yet,
because the influent flows laterally, it is exposed to a large
surface area of the settling sludge blanket, and therefore exposed
to a large surface area of anaerobic activity of the sludge
blanket.
[0077] Although the influent flows continuously, settling and
decanting proceed in a batch manner. Initially, the influent is
allowed to fill the basin 42, and the air diffusers 46 are
activated to aerate the influent. When the level of influent
reaches the normal high water level, as determined by the float
trees 48 (or any other control mechanism, such as a timer), the air
diffusers 46 are deactivated and a pump (not shown) is activated to
pump out the supernatant through the decanter 50. It is preferable
that the decanter 50 float on the surface of the influent and draw
supernatant from just below the surface of the influent. The
decanter 50 draws supernatant until the normal low level of water
is reached (or some other event occurs, such as passage of a
predetermined time). The air diffusers 46 are preferably
reactivated after enough time has passed for microbiological
processes to be completed in the settled sludge blanket, and the
cycle then starts again. A typical cycle would be 2 hours of air
diffusers and 2 hours of settling and decanting.
[0078] Preferably the decanter 50 pumps out supernatant at a rate
just less than the rate at which the sludge and other solids settle
towards the bottom, so that the decanter 50 pumps out clear
supernatant at the highest possible rate. Because the pre-react
zone director flap and other structures of the invention cause the
influent to flow into the main react zone in a laminar fashion,
there is minimal disturbance to the settled sludge blanket,
allowing it to act as a natural biological filter.
[0079] Referring to FIGS. 8 and 9, shown is a preferred embodiment
50 of the decanter of the present invention. The body 52 of the
decanter houses an airtight bladder 54 that is filled with air and
used for flotation of the entire decanter 50. Both the bladder 54
and the body 52 of the decanter have end-caps or seals 53. On the
bottom of the body 52 are a number of holes 68 to which check valve
risers 56 and a decanter pump riser 61 are attached and in fluid
communication. Risers 56 and 61 are then secured to body 52 with a
watertight seal over the holes 68 and (preferably) tack glued to
the bladder 54. A decanter pump or decanter arm is attached to the
decanter riser 61 at the decanter effluent exit port 62. At the
bottom of each of the check valve risers 56 is a ball check valve
which includes a ball 64 set into a check valve housing 63 above a
supernatant intake port 66. During operation of the decanter 50,
the decanter pump will provide a vacuum at the decanter effluent
exit port 62, and because body 52 is airtight, the supernatant will
be drawn through the intake ports 66, thus raising the balls 64 and
opening the ball check valves. The decanted supernatant will then
travel up the check valve risers 56 and out the riser holes 60 and
flow into the space 70 between the body of the decanter 52 and the
pipe bladder 54. The decanted supernatant will then be drawn
further to flow through holes 60 on the decanter pump riser 61 and
down through the decanter effluent exit port 62, to be discharged
as effluent.
WORKING EXAMPLE
[0080] Definitions:
[0081] 1. AWL Alarm Water Level
[0082] 2. ALPHA Surface tension factors
[0083] 3. AOR Actual Oxygen Requirement
[0084] 4. BWL Bottom Water Level
[0085] 5. BETA Gas solubility factors
[0086] 6. BOD-5 Biochemical Oxygen Demand
[0087] 7. CSM Oxygen Saturation Coefficient
[0088] 8. Decant To pour gently so as to not disturb the
sediment.
[0089] 9. DO Dissolved oxygen
[0090] 10. Effluent Outgoing wastewater
[0091] 11. F:M ratio Food to microorganism ratio
[0092] 12. HWL High Water Level
[0093] 13. Influent Incoming wastewater
[0094] 14. MLSS Mixed liquor suspended solids
[0095] 15. MLVSS Mixed liquor volatile suspended solids
[0096] 16. NH3-N Ammonia Nitrogen
[0097] 17. P Phosphorous
[0098] 18. SOR Standard Oxygen Requirement
[0099] 19. THETA Water Temperature
[0100] 20. TKN Total Kjeldahl Nitrogen
[0101] 21. TSS: Total suspended solids
[0102] 22. TWL Top Water Level
[0103] The following is a general overview of the design process
that has been used for designing plants.
[0104] The basic characteristics of the influent for the plant must
be determined. This includes amount of flow, strength, and type of
wastewater to be treated. The effluent requirements for the plant
must also be considered. There is a balance between what is
feasible with regards to basin sizing, and the strength of
wastewater. If it is determined that the wastewater is of a
relatively high strength, or exceeds the necessary effluent
parameter, it may be necessary to utilize one of various
pre-treatment processes. The options are either to reduce the
strength, or (possibly) size the basin to accommodate the chemical
imbalance and strength of the BOD-5 loading. The primary design
parameters are daily flow, peak flow, BOD-5, TSS, P, NH3-N, and
TKN, which are the most common characteristics for which effluent
is tested. However, the primary design parameters are not limited
to these tests and may require more extensive testing depending on
the specific project.
[0105] The number of cycles required to accommodate the various
strengths of wastewater are determined next. Preferably, between 4
to 6 cycles per day are provided to achieve a sludge age of 30 to
70 days. The sludge yield is then adjusted by applying the correct
coefficient, which may be obtained from almost any wastewater
treatment design manual, such as Wastewater Engineering,
Treatment/Disposal/Reuse, Second Edition, Metcalf & Eddy, Inc.;
M. J. Hammer, Water and Wastewater Technology, Second Edition;
Wastewater Engineering, Collection and Pumping of Wastewater,
Metcalf & Eddy, Inc.; J. W. Clark, W. Biessman, Jr., M. J.
Hammer, Water Supply and Pollution Control, Third edition; H.
Morris, J. Wiggert, Applied Hydraulics in Engineering, Second
edition; E. F. Brater & H. W. King, Handbook of Hydraulics,
sixth edition; J. A. Roberson & C. T. Crowe, Engineering Fluid
Mechanics, second edition; M. R. Lindeburg, Civil Engineering
Reference Manual, 4th edition; M. Henze, Wastewater Treatment,
Biological and Chemical Processes; and F. S. Merritt, Standard
Handbook for Civil Engineers, third edition, all of which are
incorporated herein by reference. The sludge yield is a function of
the sludge age chosen. Sludge age affects the basin size and the
stability of the system as well as sludge production. The volume
required at BWL is basically a function of waste removed and sludge
age. Following recommended parameters for sludge age and MLVSS will
almost always result in a F:M ratio between 0.05 and 0.10. Next,
the minimum alkalinity required for proper denitrification must be
calculated so that it will be greater than 158 mg/l with the
minimum P required at almost always 2.0 mg/l.
[0106] Basin geometry is calculated by the given property and
spatial requirements that are offered by the particular project and
site characteristics. Thus if the property is small, it may require
a vertical cylindrical tank versus a horizontal cylindrical tank.
Fiberglass tankage is often used for pre-packaged plants or systems
where aesthetics are important. Additionally, horizontal
cylindrical tankage provides the best mixing properties when using
diffused air. Various tank compositions such as steel, concrete,
fiberglass, lined earthen basins, or a combination of compositions
are reviewed and analyzed as required and determined by the owner,
and environmental conditions. Another option to assess is
retrofitting any existing tankage as it may offer an economical
solution to the existing wastewater treatment plant. Other factors
determining basin geometry are strength of the organic loading, and
the peak flow (which is preferably assumed to be approximately
twice the average daily flow) during a 4-hour duration. In
addition, another factor in calculating the basin dimensions is the
design MLVSS to which the wastewater plant is to be designed. Where
tank geometry size or shape is not an issue, the design tankage
should be calculated to accommodate a MLVSS of 3,500 mg/l, which
has been found to be stable. Next, the invert depth of the influent
piping should be calculated, and the sidewall depth (which is
dependent upon the depth of the basin allowable in such a setting
or environment) also should be calculated. The Bottom Water Level,
High Water Level, and Top Water Level are then calculated based on
the amount of volume required to accommodate the flow and strength
of wastewater. This amount then determines the length and width of
the wastewater treatment plant based on the overall geometry used
in the particular tank design.
[0107] Proper mixing is determined by the depth of the wastewater
in relation to the type of aeration utilized. The detention time at
the Bottom Water Level, the amount of sludge storage, and the
sludge production (preferably at 8,500 mg/l) are then calculated.
The top height of the Pre-React Zone Director is preferably
determined by the top height of the basin. The internal volume of
the Pre-React Zone Director is determined by the overall basin
geometry, and preferably is approximately 10% of the daily (or
other) incoming influent volume. The length to width ratio of the
Pre-React Zone Director is preferably approximately four to one for
narrow basin geometry, and three to two for larger basins. The
Pre-React Zone Director bottom height is calculated at a level
above the basin floor to accommodate the desired flow ratio that
one would desire. A flare or flap is preferably attached extending
downwardly approximately 120 degrees from the vertical riser of the
Pre-React Zone Director in all directions. The unique feature of a
flare or flap allows for maximum laminar flow during the settle and
decant phases of operation, and maximum flow of influent through
the settled biomass (without stirring the biomass), while adding
structural integrity.
[0108] The Influent Gate Housing diameter is calculated to
accommodate the expected influent flow velocity (whether pumped or
gravity fed) and volume into the wastewater treatment plant. The
gates within the Influent Gate Housing are situated and installed
in such a fashion to create one or multiple turbulence obstacles
which the influent will pass over. This reduces influent velocity,
and creates incidental aeration, which further reduces velocities
by the natural reversing of flow upon contact with the water level,
usually between the BWL and HWL. The gates are preferably angled
approximately 135 degrees downwardly from the vertical riser of the
housing. The number of gates is determined based on the kind of
installation required and the height to which the influent must
vertically drop to the BWL. Preferably, a base or T fitting is
provided under the bottom of the Influent Gate Housing, which
guides the influent to flow laterally. Preferably, the bottom of
the Influent Gate Housing is set at approximately half of the Top
Water Level, as determined above.
[0109] The amount of air that must be supplied to the system must
be calculated next. The goal of the air calculations is to
determine how much air must be delivered to the biomass. AOR is the
actual amount of physical oxygen uptake biologically required. AOR
is dependent on the amount of waste being removed. SOR is the
amount of oxygen that must be delivered when adjusted for
environmental conditions that affect uptake. These conditions
include elevation, THETA, the wastewater medium (as opposed to pure
water), ALPHA, and BETA. ALPHA, BETA, THETA, and CSM (a function of
wastewater temperature) are obtained from reference tables readily
available in most publications, such as Design of Municipal
Wastewater Treatment Plants, WEF Manual of Practice, which is
hereby incorporated by reference. The physical equipment required
to deliver the SOR is a function of placement, size, and efficiency
factors.
[0110] Other considerations to be taken into account in the air
formulas include the operational DO level, time of aeration and
surface tension correction factor, solubility correction factor,
temperature correction factor, average water depth, AOR and
correction factor SOR, oxygen transfer per meter of diffuser,
oxygen transfer efficiency, air required for biological removal
(which determines brake HP required), pressure, number of operating
blowers, air per meter of diffuser, and ultimately the number of
diffusers. Redundancy is very important; thus an additional standby
blower is very important in a wastewater treatment plant.
[0111] Decanter pump sizing is determined by dividing the expected
daily flow by the number of decant cycles desired per day to find
the volume of flow per decant cycle, and then choosing the pump
size necessary to pump that volume during the pump portion of a
decant cycle, preferably with a redundancy added for maintenance.
The effluent flow, velocity, and head loss incurred is another
factor in decanter and pump sizing.
[0112] Preferably, a novel floating decanter is used that requires
little to no maintenance because it is made of non corrosive
materials (such as PVC). It decants supernatant from just below the
surface and therefore does not decant floating solids or scum. It
does not have any chain adjusting mechanisms or mechanical arm, is
non-mechanical, contains no springs, has a PVC flotation bladder
that does not require replacement but is not limited to such. It
has recessed check valves that are not exposed to horizontal
hydraulic and aeration turbulence found with other decanters. An
advantage of having recessed check valves is that a small
stationary bubble forms around the decanter port during the
aeration phase of operation causing other bubbles to deflect away
from the decanter port and avoid hitting the ball in the check
valve, so that the check valve remains undisturbed and does not
allow solids ("mixed liquor") to pass through. This allows the
weight of the ball in the check valve to be reduced, thus reducing
the electrical load on the decanter pump. This results in a
superior supernatant. The check valves are also preferably made of
non-corrosive materials. All components are readily available and
the decanter is easily manufactured. The decanter is usually
designed using a single row of decanter ports, but is not limited
to such in larger systems. Thus, in larger systems, two or more
rows of decanters can be connected together using simple "T"
fittings, reducers, and cross fittings. In order to calculate the
number of ports required for a decanter: calculate the buoyancy of
the ball-check-valves by utilizing sphere diameter, sphere weight,
and the specific weight of water. Calculate the minimum pressure to
lift the ball, buoyancy and weight to determine the force required
to lift the ball. Use expected flow, head loss, port sizes, and
velocity to determine the number of ports at a maximum flow
velocity of approximately 11/2 meters (5 feet) per second by each
port. This decanter's maintenance free characteristics allow the
owner or buyer to save capital, energy, and maintenance costs.
Preferably, the discharge line for the decanter extends through the
wall of the basin and is located just below the Bottom Water Level
or (BWL).
[0113] Emergency gravity overflow is provided, sized, and
calculated per the influent flow. The emergency gravity overflow is
usually situated on the basin opposite the influent flow at a depth
lower than the incoming influent invert. Preferably, a standard "T"
fitting is attached to the overflow pipe with a downward extension
of approximately 1/3 to 2/3 meters (12 to 24 inches) so that
floating solids will not be gravity fed out the emergency gravity
overflow. All fittings for this emergency gravity overflow are
preferably "Y" fittings. It is advisable not to utilize 90-degree
fittings, as the emergency overflow may become restricted.
[0114] The type and amount of available electrical power must be
considered in finalizing all control, blower, and pump sizing.
[0115] Automation of the process is preferably provided by various
float switches in conjunction with a clock. The clocks' primary
purpose is to control the length and time of the aeration, and
decant cycles. The BWL is kept at a minimum by the BWL float
switch, which opens the decanter circuit (thus deactivating the
decanter pump) during the decant cycle determined by the clock when
the minimum level is met. Should an abnormal condition exist, the
HWL switch would open the circuitry to the aeration cycle causing
the aeration cycle to cease and go into a settle phase. The TWL
switch would then close the decant circuit which bypasses the clock
timer and starts an early decant until the circuit is opened.
Should the emergency condition continue, the level would then close
a AWL circuit causing selected conditions to occur such as a horn,
light etc. to notify the proper authority. If the emergency
condition should continue, the system would gravity overflow until
the situation is remedied.
[0116] While the present invention has been disclosed in connection
with the presently preferred embodiments described herein, there
are other embodiments within the skill of a person of ordinary
skill in the art that fall within the spirit and scope of the
invention as defined by the claims. Because wastewater treatment
plants vary in size and shape, and because of the highly
customizable nature of this invention to fit the needs of a
particular wastewater treatment system, there exist many variations
and configurations of the presently preferred embodiments described
above.
[0117] For example, there may be multiple influent gate housings 20
encompassed within a single pre-react zone director 34.
Furthermore, multiple pre-react zone directors 34 may be utilized
within a single basin 42.
[0118] The influent gate housing 20 may be in the shape of a
downward spiral or some other design.
[0119] The influent gate housing bottom 30 may utilize a base that
directs flows upward, downward, or other angle other than
horizontal.
[0120] The pre-react zone director 34 may utilize a manually or
automatically adjustable flap, or the pre-react zone director
itself may be manually or automatically adjustable to vary the size
of the contact zone by varying the height of the pre-react zone
director from the bottom of the basin 42.
[0121] The pre-react zone director 34 may utilize multiple
flaps.
[0122] This invention can be installed below ground if it is vented
and if freezing can be prevented.
[0123] Accordingly, no limitations are to be implied or inferred in
this invention except as specifically and explicitly set forth in
the claims.
[0124] Industrial Applicability
[0125] This invention can be used whenever it is desired to have a
secondary wastewater treatment system that achieves results
comparable to tertiary wastewater treatment systems. This invention
can be used whenever it is desired to utilize a highly efficient,
low cost wastewater treatment system that produces high quality
effluent on minimal land. This invention can be used when currently
existing systems are inadequate or do not meet environmental
standards or other requirements. For example, if existing cesspools
or septic tanks are inadequate to accept additional wastewater, or
if a sewage infrastructure has not been connected to a particular
location, then this invention can be used to increase or provide
wastewater and sewage treatment.
* * * * *