U.S. patent application number 11/425855 was filed with the patent office on 2007-12-27 for a method of treating stormwater runoff and domestic waste with coal ash.
Invention is credited to Bobby L. Joyner, Robert J. Waldrop.
Application Number | 20070295661 11/425855 |
Document ID | / |
Family ID | 38863258 |
Filed Date | 2007-12-27 |
United States Patent
Application |
20070295661 |
Kind Code |
A1 |
Joyner; Bobby L. ; et
al. |
December 27, 2007 |
A METHOD OF TREATING STORMWATER RUNOFF AND DOMESTIC WASTE WITH COAL
ASH
Abstract
A method of treating wastewater, and more particularly
stormwater runoff or domestic waste, wherein the wastewater is
directed through a high carbon ash particulate. Contaminants such
as phosphorus, nitrogen, BOD and COD can be removed. In addition,
treatment of the stormwater runoff or domestic waste with ash will
raise the pH of the wastewater, generally to above 10, killing
bacteria contained in the wastewater.
Inventors: |
Joyner; Bobby L.; (Rocky
Mount, NC) ; Waldrop; Robert J.; (Canton,
GA) |
Correspondence
Address: |
COATS & BENNETT, PLLC
1400 Crescent Green, Suite 300
Cary
NC
27518
US
|
Family ID: |
38863258 |
Appl. No.: |
11/425855 |
Filed: |
June 22, 2006 |
Current U.S.
Class: |
210/631 ;
210/660 |
Current CPC
Class: |
C02F 1/283 20130101;
E03F 5/18 20130101; C02F 2103/001 20130101; C02F 1/66 20130101;
Y10S 210/906 20130101; Y10S 210/903 20130101 |
Class at
Publication: |
210/631 ;
210/660 |
International
Class: |
C02F 1/28 20060101
C02F001/28 |
Claims
1. A method of treating stormwater runoff comprising directing the
stormwater runoff through ash and utilizing the ash to remove one
or more pollutants from the stormwater runoff.
2. The method of claim 1 including pretreating the ash to remove
sulfates and metals.
3. The method of claim 2 including placing the ash in a chamber and
directing the runoff into the chamber and through the ash.
4. The method of claim 1 including utilizing ash from a furnace
which burns coal with or without other fuels.
5. The method of claim 4 including burning coal with or without
other fuels in a furnace to produce the ash.
6. The method of claim 1 wherein the ash comprises ash particles
and wherein the ash particles are generally smaller than 3/8'' and
large enough not to pass through a no. 50 sieve.
7. The method of claim 1 including containing the ash in a porous
container and directing the stormwater runoff through the container
and the ash therein.
8. The method of claim 1 including containing the ash in a
geotexile filter medium.
9. The method of claim 1 including screening the ash to produce
particles of ash of a particular size.
10. The method of claim 1 further including directing the
stormwater runoff through a sand removing device that removes sand
from the stormwater runoff.
11. The method of claim 1 wherein the ash removes nitrogen,
phosphorus, BOD or COD from the stormwater runoff.
12. The method of claim 1 including pretreating the ash by washing
the ash and removing at least some sulfates and metals from the
ash.
13. The method of claim 1 including raising the pH of the
stormwater runoff to 10 or higher by contacting the stormwater
runoff with the ash.
14. The method of claim 13 wherein the stormwater runoff is at
least slightly acidic.
15. The method of claim 1 including producing the ash from coal
having a sulfur content of 3% or less.
16. The method of claim 1 wherein a tire derivative fuel and/or
wood comprises approximately 10% to 20% of a fuel burned to produce
the ash.
17. The method of claim 16 wherein the tire derivative fuel is
produced by removing metal from tires and cutting the tires into
pieces.
18. The method of claim 1 including directing the stormwater runoff
through a sand removal device, and thereafter into a chamber having
the ash disposed therein.
19. (canceled)
20. (canceled)
21. (canceled)
Description
FIELD OF THE INVENTION
[0001] The present invention relates to wastewater treatment, and
more particularly to treating stormwater runoff and domestic waste
with a high carbon particulate composition such as coal ash.
BACKGROUND OF THE INVENTION
[0002] Government discharge regulations have long recognized the
dangers of discharging wastewater with significant concentrations
of phosphorus and nitrogen. Most states have stringent requirements
mandating that phosphorus and nitrogen concentrations in effluents
discharged from wastewater treatment plants be extremely low. These
regulations, of course, apply to municipal, county and regional
wastewater treatment plants. However, the dangers associated with
nitrogen and phosphorus concentrations in wastewater are not
confined to conventional wastewater treatment processes conducted
by wastewater treatment plants. Stormwater runoff contains a
significant amount of phosphorus, nitrogen, and other pollutants.
Many states and government entities are beginning to direct
attention to reducing the phosphorus and nitrogen concentrations in
stormwater runoff.
[0003] In some locations, local governments have issued guidelines
requiring that phosphorus and nitrogen be removed from certain
stormwater runoff, and have required the installation of structures
in an effort to reduce nitrogen and phosphorus pollutants from
stormwater runoff. However, for the most part the types of
structures and systems being utilized to deal with phosphorus and
nitrogen in stormwater runoff have been inefficient and expensive
to build and maintain. Many such systems and processes only remove
approximately 25% to 50% of the nitrogen and phosphorus in the
stormwater runoff.
[0004] There is a need for an efficient filtering system that is
relatively inexpensive, easy to maintain, and which will remove
substantial concentrations of phosphorus, nitrogen, and other
pollutants from stormwater runoff and other types of wastewater,
such as domestic wastewater.
SUMMARY OF THE INVENTION
[0005] The present invention relates to a system and method for
removing pollutants such as phosphorus, nitrogen, BOD and COD from
stormwater runoff. The method entails directing the stormwater
runoff through processed ashes. In one embodiment, the ashes are
coal combustion products (CCP's). In another embodiment, the ashes
are the result of burning coal along with Tire Derived Fuel (TDF)
and/or wood. With either case, the residual carbon content of the
ashes in a preferred embodiment is approximately 10 to 20 percent
which enables them to remove pollutants from stormwater runoff.
[0006] Further, the present invention relates to a method of
treating domestic waste by utilizing ash to treat the wastewater
prior to the wastewater being discharged into a drain field. In one
embodiment, domestic waste is directed from a residential structure
to a septic tank. From the septic tank the wastewater is directed
through an aerobic and anaerobic bacteria filter media, and the
effluent therefrom is directed to a polishing chamber that includes
ash. The wastewater is directed through the ash and thereafter is
discharged in a drain field.
[0007] Other objects and advantages of the present invention will
become apparent and obvious from a study of the following
description and the accompanying drawings which are merely
illustrative of such invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a schematic illustration showing the stormwater
runoff treatment process of the present invention.
[0009] FIG. 2 is a fragmentary cross-sectional view illustrating a
sand removal device that forms a part of the system and process
shown in FIG. 1.
[0010] FIG. 3 is a schematic illustration of a domestic wastewater
treatment process according to the present invention.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0011] The present invention relates to utilizing ash to treat
wastewater. In particular, the method and process of the present
invention relates to treating stormwater runoff or domestic
wastewater. In either case an ash filtering material is utilized to
remove such pollutants as nitrogen, phosphorus, BOD and COD from
the wastewater being treated.
[0012] Turning to FIGS. 1 and 2, shown therein is a system and
process for treating stormwater runoff. Stormwater runoff is first
directed to a sand removing device indicated generally by the
numeral 10. As illustrated in FIG. 1, sand removing device 10
includes an inlet 12 for receiving the stormwater runoff. Disposed
adjacent inlet 12 is a grate 14 that overlies a sand chamber 16.
Sand chamber 16 includes a bottom 16B and a surrounding wall
structure 16A. In conventional fashion, sand removing device 10 may
include an additional inlet in the form of a pipe 18 that is
directed to one sidewall 16A. Extending from sidewall 16A is an
outlet pipe 20. As seen in FIG. 2, the sand removal device 10
includes a baffle 22 that is disposed inside the chamber 16 and
adjacent an opening that leads to the outlet pipe 20. Note that the
baffle 22 includes a bottom opening 22A that is disposed below the
level of the outlet pipe 20. This will prevent the wastewater
received in chamber 16 from directly passing from the chamber 16 to
the outlet pipe 20 without an opportunity for sand, grit and other
debris to settle in the chamber. For example, as illustrated in
FIG. 2, the wastewater in chamber 16 assumes a level above the
bottom 22A of the baffle 22. Hence, for wastewater to exit via the
pipe outlet 20, it follows that the wastewater must move downwardly
and up through the opening 22A formed in the baffle. As illustrated
in FIG. 2, through this process sand, grit and other debris tends
to settle on the bottom of chamber 16. Hence, the sand removal
device 10 tends to remove suspended solids such as sand, grit,
debris and other suspended particulate material.
[0013] Downstream from the sand removing device 10 is a treatment
chamber indicated generally by the numeral 60. As will be
appreciated from subsequent portions of this disclosure, the
treatment chamber includes an ash filtering material 100. Viewing
the treatment chamber in more detail, the same includes a bottom 62
and a pair of sides 64 and 66. Disposed on opposed ends of the
treatment chamber 60 is a pair of ends 68. A top 70 extends over
the treatment chamber 60. Disposed over the bottom 62 is a series
of spaced apart members 74. Spaced apart members 74 define a series
of open channels between the respective members 74. Disposed
intermediately between ends 68 is an upstanding baffle 76. Baffle
76 divides the treatment chamber 60 into an ash chamber 80 and an
outlet section 82. Formed in the outlet section 82 is an outlet 84
that permits filtered water to move from the treatment chamber
60.
[0014] Formed in one side 66 is an overflow opening 78. Disposed
within the ash chamber 80 is the ash filtering material 100. The
ash 100 preferably contains coal ash and could contain other carbon
sources. For example, the ash 100 may contain coal ash and ash from
other fuels such as tire derived fuel and/or wood. The composition
of ash 100 is sometimes referred to as pillow ash inasmuch as the
ash material 100 is contained within a porous container, bag or
even a geotextile filter media.
[0015] In the case of the embodiment illustrated in FIG. 1,
stormwater runoff is directed from the sand removal device 10
through outlet pipe 20 into the ash chamber 80. There the
stormwater runoff filters down through the bed of ash material 100
and into the open channels that extend along the bottom 62 between
the respective members 74. The treatment chamber 60 can be slightly
inclined such that the water flows towards the outlet section 82 of
the treatment chamber 60. Baffle 76 is slightly elevated over the
bottom 62 such that water, which has been filtered by the ash 100,
passes thereunder and out outlet 84.
[0016] In many cases the stormwater runoff directed into the
treatment system of FIG. 1 will include nitrogen, phosphorus, BOD,
COD, oil and grease, petroleum hydrocarbons, and suspended solids.
The ash will react with these pollutants or contaminants and the
reaction will result in substantial portions of these pollutants
being removed from the stormwater runoff being filtered through the
ash 100. It is hypothesized that the carbon content of the ash will
bind with these pollutants or contaminants causing them to be
removed from the stormwater runoff passing through the ash 100.
[0017] Below, in Tables I and II is preliminary data relating to a
series of tests where various samples of stormwater runoff was
filtered by ash. Table I represents a series of tests conducted
with one ash sample, denoted ash sample No. 1. In this case, raw
water was first directed through the ash sample and the effluent
was collected and analyzed. In the case of raw water, it is seen
that, for example, the BOD (5-day) concentration of the effluent
was 4.8 mg/l. Total nitrogen concentration was 1.4 mg/l and total
phosphorus concentration was 0.168 mg/l. After the sample of raw
wastewater was tested, a series of stormwater runoff samples was
sequentially directed through the same ash sample. In particular,
five different samples of stormwater runoff were directed, one
after the other, through the ash sample. In each case effluent was
collected and analyzed. Note that the effluent of the fourth
stormwater runoff sample, for example, included a total nitrogen
concentration of less than 1.08 mg/l and a total phosphorus
concentration of less than 0.050 mg/l. While the concentrations of
the various noted pollutants or contaminants were not measured in
the sample prior to filtration through the ash sample, the test
does verify that the ash is effective to reduce the concentration
of these pollutants and that the ash has an ongoing capacity to
treat stormwater runoff without its effectiveness being seriously
depleted by initial contact with stormwater runoff.
TABLE-US-00001 TABLE I Ash - Sample I Stormwater Stormwater
Stormwater Stormwater Stormwater Pollutants or RAW Runoff Runoff
Runoff Runoff Runoff Contaminants WATER Sample 1 Sample 2 Sample 3
Sample 4 Sample 5 BOD (5 Day), mg/l 4.80 <2.14 <2.14 <2.00
<2.00 <2.00 Chemical Oxygen Demand, 65.50 15.5 35.5 30.5 13
18 mg/l Nitrogen: Kjeldahl (as N), 1.21 <1.00 <1.00 4.04
<1.00 <1.00 mg/l Nitrogen: Nitrate (as N), 0.129 0.164 0.142
0.196 0.063 0.064 mg/l Nitrogen: Nitrite (as N), mg/l 0.056
<0.025 <0.025 0.044 <0.010 <0.010 Nitrogen: Total (as
N), mg/l 1.40 <1.08 <1.08 4.28 <1.08 <1.05 Oil and
Grease, mg/l <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 Total
Petroleum <5.0 <5.0 <5.0 <5.0 <5.0 <5.0
Hydrocarbon, mg/l Phosphorus: Ortho (as P), 0.281 0.298 0.279 0.100
<0.050 0.109 mg/l Total Phosphorus (as P), 0.168 <0.050
<0.050 <0.050 <0.050 <0.050 mg/l Solids: Total
Suspended 7 <1 <1 <1 <1 <1 Solids: Settleable
<0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Sulfate 1.25 14.4
3.60 2.54 1.68 1.54
TABLE-US-00002 TABLE II Ash - Sample II Stormwater Stormwater
Stormwater Stormwater Stormwater Pollutants or RAW Runoff Runoff
Runoff Runoff Runoff Contaminants WATER Sample 2 Sample 3 Sample 4
Sample 5 Sample 6 BOD (5 Day), mg/l 25.1 <2.00 <2.00 <2.00
<2.00 <2.00 Chemical Oxygen Demand, 30.5 26.8 20.5 43.0 90.5
38.0 mg/l Nitrogen: Kjeldahl (as N), <1.00 <1.00 <1.00
1.70 2.62 2.48 mg/l Nitrogen: Nitrate (as N), 0.128 0.070 0.058
0.060 0.064 0.062 mg/l Nitrogen: Nitrite (as N), mg/l 0.059 0.019
<0.010 0.018 <0.010 0.182 Nitrogen: Total (as N), mg/l
<1.08 <1.05 <1.05 1.78 2.68 2.72 Oil and Grease, mg/l
<5.0 <5.0 <5.0 <5.0 <5.0 <5.0 Total Petroleum
<5.0 <5.0 <5.0 <5.0 <5.0 <5.0 Hydrocarbon, mg/l
Phosphorus: Ortho (as P), 0.274 <0.050 0.109 0.114 <0.050
<0.050 mg/l Total Phosphorus (as P), <0.050 <0.050
<0.050 <0.050 <0.050 <0.050 mg/l Solids: Total
Suspended 4 <1 <1 <1 <1 <1 Solids: Settleable
<0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Sulfate 1.62 16.3
6.20 4.74 3.57 3.53
[0018] Turning to FIG. 3, the schematic shown therein illustrates a
domestic wastewater treatment system such as the type that would be
found associated with a residential dwelling that does not have
access to county or municipal sewer. The domestic wastewater
treatment system is indicated generally by the numeral 120. It
includes a conventional septic tank 122. Downstream from the septic
tank 122 is a pump or holding tank 124 that holds wastewater
effluent from the septic tank 122. From the pump tank 124 the
wastewater effluent is directed to chamber 126. Chamber 126 in this
embodiment constitutes a conventional aerobic and anaerobic
bacteria filter media. From chamber 126 the wastewater is directed
to a polishing stage. In the polishing stage there is provided a
chamber 128 that includes a filtering material that includes ash
100. Wastewater from chamber 126 is directed into a top portion of
chamber 128 and thereafter the wastewater filters downwardly
through the ash 100 and is treated in the process. For large
systems, multiple ash chambers could be utilized. Effluent from
chamber 128 is directed to a distribution box 129 and therefrom to
a conventional drain field 130.
[0019] As discussed above with respect to stormwater runoff, the
ash 100 in chamber 128 is effective to remove pollutants such as
phosphorus, nitrogen, BOD and COD from the wastewater being treated
by the domestic wastewater system 120.
[0020] Preferably, the filtering composition disclosed with respect
to the processes herein would be comprised substantially of ash.
Other filtering materials, or other materials that are effective to
remove pollutants can be mixed with the ash. But in a preferred
embodiment, the filtering material 100 would be comprised
substantially of ash.
[0021] In a preferred embodiment, the ash contains coal ash. Coal
ash refers to the residue produced in power plant boilers or coal
burning furnaces, for example, chain grate boilers, pulverized coal
boilers and fluidized bed boilers, from burning pulverized
anthracite or lignite, or bituminous or sub-bituminous coal.
Generally, coal ash with a relatively high carbon content is
preferred. The carbon content should be 10% or more and preferably
above 20%. Furthermore, the coal from which the coal ash is
produced is preferred to be low sulfur coal which generally, for
purposes of this disclosure, is considered to be coal having a
sulfur content of 3% (by weight) or less. In some cases the
filtering material utilized in the present invention is produced
from co-firing alternative fuels such as tire derivative fuel
and/or wood with coal. Typically, such alternative fuels would
comprise less than 20% of the total volume of fuel burned to
produce the filtering material.
[0022] The term "ash" is used herein to describe a filtering
material used to treat wastewater. The term "ash" as used herein
means coal ash or wood ash and ashes from the combustion of other
fuels. For example, as discussed above, coal could be mixed with a
tire derivative fuel or wood, and all the components burned in a
furnace. The ash from the coal, tire derivative fuel and/or wood,
could be utilized together as the filtering material. In this case,
it is contemplated that the ash from the tire derivative fuel
and/or wood would comprise no more than about 20% of the total ash
material used for the filtering material.
[0023] The ash is typically processed or treated prior to use.
First, the ash is screened to a specific size range to maximize or
take advantage of the carbon content of the ash. Generally, a
preferred size range includes particles of a size of 3/8'' or less
and sufficiently large to be screened by a No. 50 screen.
Furthermore, the ash should be processed to remove excess sulfates
and metals. This can be achieved by washing the ash prior to use.
In the case of utilizing the ash to remove pollutants from
stormwater runoff, the ash will be treated such that any subsequent
leachate from stormwater runoff or other sources will meet
regulatory surface water standards.
[0024] The ash utilized in the systems and processes discussed
above would be manufactured or packaged either loosely or in bags
of a particular shape and size, and in some cases would be wrapped
in a non-woven geotextile filter media to contain the granular
material. The bags of ash could be placed inside various types of
structural containers or elements such as a Delaware sand filter,
or other structures such as fiberglass chambers or reactors. The
bags of ash would permit easy removal and replacement from a
structure by maintenance personnel.
[0025] The present invention may, of course, be carried out in
other specific ways than those herein set forth without departing
from the scope and the essential characteristics of the invention.
The present embodiments are therefore to be construed in all
aspects as illustrative and not restrictive and all changes coming
within the meaning and equivalency range of the appended claims are
intended to be embraced therein.
* * * * *