EPA-BQO/2-77-115
Septsratir lill
FIELD PROTOTYPE DEMONSTRATION
OF THE SWIRL DEGRITTER
Municipal Environmental Research Laboratory
of and Devetepmiit
U.S. Emfronmintil Protection Agency
Cincinnati, Ohio 45268
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EPA-600/2-77-185
September 1977
FIELD PROTOTYPE DEMONSTRATION OF THE SWIRL DEGRITTER
by
Richard H. Sullivan
James E. Ure
Paul Zielinski
American Public Works Association
Chicago, Illinois 60637
Grant No. S-803157
Project Officers
Richard Field
Hugh Masters
Storm and Combined Sewer Section
Wastewater Research Division
Municipal Environmental Research Laboratory (Cincinnati)
Edison, New Jersey 08817
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Municipal Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publica-
tion. Approval does not signify that the contents.necessarily reflect the
views and policies of the, U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
ii
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FOREWORD
The Environmental Protection Agency was created because of increasing
public and government concern about the dangers of pollution to the health
and welfare of the American people. Noxious air, foul water, and spoiled
land are tragic testimony to the deterioration of our natural environment.
The complexity of that environment and the interplay between its compo-
nents require a concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem
solution and it involves defining the problem, measuring its impact, and
searching for solutions. The Municipal Environmental Research Laboratory
develops new and*improved technology and systems for the prevention, treat-
ment, and management of wastewater and solid and hazardous waste pollutant
discharges from municipal and community sources, for the preservation and
treatment of public drinking water supplies and to minimize the adverse
economic, social, health, and aesthetic effects of pollution. This pub-
lication is one of the products of that research; a most vital communica-
tions link between the researcher and the user community.
The study describes the evaluation of a prototype swirl degritter to
perform the function of grit separation more effectively than conventional
units for concentrated grit :as may be found in the treatment of stormwater
discharges.
Francis T. Mayo
Director
Municipal Environmental Research Laboratory
iii
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ABSTRACT
A prototype swirl degritter was tested by the Metropolitan Denver
Sewage Disposal District No. 1. The unit was designed to duplicate the
grit removal device needed to degrit the underflow from the proposed swirl
concentrator as a combined sewer overflow regulator at Lancaster,
Pennsylvania under EPA Grant No. S802219 (formerly 11023 GSC) . Degritting
is considered in Lancaster to protect pumps and prevent siltation in the
interceptor .
The 1.8 m (6 ft) diameter device was designed for a flow of 65, 6 1/s
(1.5 mgd). It was found that under the physical arrangements in Denver,
and testing with domestic sanitary wastewater, that the swirl unit per-
formed at slightly less efficiency than the conventional aerated grit unit
which was operating at less than twice the normal flow- through rate. The
characteristics of the grit removal from the swirl degritter were excellent
and particles of 0.2 mm (.008 in) were removed.
Analyses of grit removal was accomplished with three Chasick sampling
units. Blasting sand was added to provide extremely high concentrations of
0.2 mm (.008 in) particles (lower definition of grit) to duplicate the con-
centrate from the swirl regulator. It was found that the unit could effi-
ciently remove the small particles at the high concentrations.
It was concluded that the degritter could be used for domestic waste-
water, combined sewer overflows, or urban stormwater runoff treatment.
The absence of moving parts in the basic unit and small relative volume^ltlO
grit chambers.) may make the unit particularly de-
sirable for many applications. A comparison of the present wnrf-Ti of
cost of construction, operation and maintenance for a 20- year life indi-
cates that the swirl degritter is from 26 to 38 percent less costly than a
conventional aerated grit chamber. "
This report is submitted in partial fulfillment of EPA Grant S803157
by the American Public Works Association under the sponsorship of the U.S.
Environmental Protection Agency. This report covers a period from January,
1975 to August, 1976, and work was completed as of December, 1976.
iv
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CONTENTS
Foreword ..... iii
Abstract ..... iv
Figures * . vi
Tables viii
Acknowledg'ments x
1. Conclusions and Recommendations 1
2. The Demonstration Project 2
3. Description of the Test layout . 5
4. Evaluation of Test Results 13
References <> 55
Appendix
A. Test Data, Denver, Colorado 56
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FIGURES
Number . Page
1 Isometric View, Swirl Degritter 4
2 Layout for Denver Tests 6
3 Plan of Swirl Degritter , . . . 7
4 Section A-A of Swirl Degritter 8
5. Section B-B of Swirl Degritter 9
6 Chasick Grit Sampler " 11
7 Denver Tests Grit Gradation Curves, 5/23-6/21, First Series . . 19
8 Gradation. Curve of Spiking Sand 22
9 Removal of Dry Grit, 8/75 26
10 Weight of Dry Grit, 8/75 27
11 Removal of Grit Ash, 8/75 31
12 Weight of Grit Ash, 8/75 32
13 Grit Gradation Curves, Run No. 1, 8/75 41
14 Grit Gradation Curves, Run No. 2, 8/27/75 41
15 Grit Gradation Curves, Run No. 3, 8/27/75 41
16 Grit Gradation Curves, Run No. 4, 8/27/75 41
17 Grit Gradation Curves, Run No. 5, 8/27/75 '42
18 Grit Gradation Curves, Run No. 1, 8/28/75 42
19 Grit Gradation Curves, Run No. 2, 8/28/75 42
20 Grit Gradation Curves, Run No. 3, 8/28/75 42
21 Grit Gradation Curves, Run No. 4, 8/28/75 43
vi
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FIGURES (continued)
Number Page
22 Grit Gradation Curves, Run No. 5, 8/28/75 43
23 Grit Gradation Curves, Run No. 1, 8/29/75 43
24 Grit Gradation Curves, Run No. 2, 8/29/75 43
2-5 Grit Gradation Curves, Run No. 3, 8/29/75 44
26 Grit Gradation Curves, Run No. 4, 8/29/75 44
27 Grit Gradation Curves, Run No. 5, 8/29/75 44
28 Grit Gradation Curves, Run No. 1, 8/30/75 44
29 Grit Gradation Curves, Run No. 2, 8/30/75 45
30 Grit Gradation Curves, Run No. 3, 8/30/75 45
31 Grit Gradation Curves, Run No. 4, 8/30/75 45
t
32 Grit Gradation Curves, Run No. 5, 8/30/75 45
vii
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TABLES
Number Page
1 Detention Times 10
2 Proposed Tests-First Series—5/23-6/21/75 14
3 Removal of Grit Ash—5/23-6/21/75 16
4 Removal of Dry Grit--5/23-6/21/75 17
5 Removal of Suspended and Volatile Solids--5/23-6/21/75 18
6 Proposed Tests Seconds Series--8/27-8/31/75 ....,,..._... 21
7 Removal of Dry Grit--8/27-8/30/75 ; 23
8 Removal of Grit Ash--8/27/75 24
9 Removal of Grit Ash--8/28/75 28
10 Removal of Grit Ash--8/29/75 29
11 Removal of Grit Ash—8/30/75 30
12 Removal of Volatile Solids—5/23 to 6/21/75 33
13 Removal of Volatile Solids—8/27/75 34
14 Removal of Volatile Solids—8/28/75 35
15 Removal of Volatile Solids—8/29/75 36
16 Removal of Volatile Solids—8/30/75 37
17 Aerated Grit Chamber, Single Chamber High Flow Efficiency .... 46
18 Construction Cost of Swirl Degritter ' . 50
19 Construction Cost of Conventional Aerated Grit Chamber 51
20 Operation and Maintenance Costs for Grit Removal 53
21 Present Worth, Grit Removal Units 54
viii
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TABLES (continued)
Number Page
A-l Test Data Swirl Flow 43.8 1/s (1.0 mgd) , 5/23-5/29/75 56
A-2 Test Data Swirl Flow 87.6 1/s (2.0 mgd), 5/31-6/6/75 57
A-3 Test Data Swirl Flow 131.4 1/s (3.0 mgd), 6./12-16 & 20-21/75 . . 58
A-4 Test Data Swirl Flow 21.9 1/s (0.5 mgd), 8/27/75 59
A-5 Test Data Swirl Flow 43.8 1/s (1.0 mgd), 8/2S/75 60
A-6 Test Data Swirl Flow 87.6 1/s (2.0 mgd), 8/29/75 61
A-7 Test Data Swirl Flow 131.4 1/s (3.0 mgd), 8/30/75 62
A-8 Aerated Grit Chamber Data, Single Chamber High Flow 0 „ „ . . . 63
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ACKNOWLEDGEMENTS
The American Public Works Association is deeply indebted to the follow-
ing persons and their organizations for the services they have rendered to
the APWA Research Foundation. The initiative of the Metropolitan Denver
Sewage Disposal District No. 1 in providing the prototype swirl degritter
for the comparison studies is acknowedged.
PROJECT DIRECTOR
Richard H. Sullivan
CONSULTANTS
Paul B. Zielinski, P.E.
James E. Ure, P.E,, Alexander Potter Associates, Consulting Engineers
Morris H. Klegerman, P.E., Alexander Potter Associates, Consulting Engineers
F. E. Parkinson, LaSalle Hydraulic Laboratory, Ltd.
PROJECT OFFICERS
Richard Field, P.E. Chief
Hugh Masters, Staff Engineer
Storm and Combined Sewer Section
Wastewater Research Division
Municipal Environmental Research Laboratory (Cincinnati)
Edison, New Jersey 08817
METROPOLITAN DENVER SEWAGE DISPOSAL DISTRICT NO. 1
William Korbitz, P0E.
Al Jacobs
x
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SECTION I
CONCLUSIONS AND RECOMMENDATIONS
CONCLUSIONS
1.
The swirl degritter can efficiently and effectively remove grit from all
wastewater flows. Even though the percent dry grit removal in the aerated
gf^t cfoapber jEtm-jcaaLsgnj^ayy fjewage_was consistently higher (77.3 per—
cent) than that accomplished in the ^ii-1 rlppHf-t-ov (&{,.&. pen-rent") , the
aerated grit nT-iamber Detained an undesirably higher—Percentage of organic
particles
than the swirl unit .9-30 percent for the
aerated grit chamber as compared to 3-10 percent for—the.
'To test the effectiveness of the swirl degritter in removing grit from
combined sewer overflow and overflow concentrate, the plant influent was
spiked by adding blasting sand (0.20 mm size). Removal efficiencies under
these conditions were improved for the swirl unit. They ranged from 50
to 87 percent for the swirl degritter; and for the aerated grit chamber
,the range was considerably lower.
2. The swirl degritter remains effective at flows of twice the design flow.
Efficiency"falls off markedly at three times design tiow, which is similar
to other types of degritters.
3. Because the swirl degriiLter is compact in size and has no moving__parJis—it
is attractp™ fn-r application on__stormwater. combined^sewer overflows, or
treatment at remote locations where maintenance capability is limited.
Such degritting may be desirable prior to pumping of the flows.
4. Since the swirl unit requires no aeration or moving parts in its internal
operation, energy consumption/unit flowrate for this unit is less than
any other__me±liQd_Qf__grit removal.
5. Because of the mechanics of flow in the swirl degritter, the detention
time in__the_unit is one minute or less as compared to a standard design
of about three minutesTo? a conventional aerated grit chamber.
Cp Jl
6. The present worth, including construction, operation, and maintenance of
the swirl degritter compared to an aerated grit chamber indicates a sav-
ings of 26 percent for a 43.8 1/s (1 mgd) unit to 38 percent for a 438
1/s (10 mgd) unit.
RECOMMENDATIONS
1. The City of Lancaster, in conjunction with the construction of a swirl
concentrator as a combined sewer overflow regulator, should consider
constructing a swirl concentrator as a grit chamber to reduce maintenance
on its lift pumps. gf+ T>,4 }u+,*L u**»r &C&S /J4&6'"*\ /.
2. Agencies that construct swirl degritters should Jbe encouraged to install
Chasick sampling units on the influent and effluent lines to enable further
testing of the ef f iciencyortn^!**unTts . ^^^^""
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SECTION II
THE DEMONSTRATION PROJECT
A related family of research studies has been carried out during the
past four years to determine the ability of solids-liquids separation flow-
through devices to remove unwanted solids in wastewater flows by means of
induced swirl pattern hydraulic flows in time periods shorter than those
required by conventional gravity separation treatment systems. The success
of laboratory-based investigations in small-scale chambers on synthesized
wastewater flows has led, progressively, to consideration and, study ot the
application of such swiri concentration champers ror s'U'Cfl purposes as com-
bined sewer overt! ow regulation, grit removal trom wastewater tiows, pri-
mary clar it lea ffiori of Wasteaters and erosion control devices.
A "firgf--generation" study was carried out on behalf of the U.S. En-
vironmental Protection Agency (USEPA), by the American Public Works Associ-
ation (APWA) Research Foundation to develop and investigate the feasibility
of utilizing a swirl device to perform the dual function of hydraulically
:-?nft nyerflows from a combined sewer system whilf |ginnfltaneously1 re-
the solids content and pollutional characteristics of the overflows
discharged to receiving water by solids-lTqu'id^sepltration. The first report
(1) recognized the applicability of the swirl separation principle for other
than the combined sewer overflow regulator-separator.
It is obvious that a natural application of this relatively "flash-
fcype" solids-liquid phase reparation would be the removal of heavier grit
from wastewater flows because such solids are more readily treatable because
of their higher settling velocities, it was a rie'w" innovation in the separ-
ation of heavy inorganic solids from lighter organic materials by selective
use of longitudinal flow velocities. It also offered opportunities to
effectively remove grit from either the underflow concentrate (foul sejfer
discharge), of a swirl concentrator combined sewer overflow regulator or
from normal dry-weather and wet-weather intluents into Lt'eilLmenc plants.
A "second-generation" study followed to develop and evaluate the_awirl
concentrator for grit ""removal"Tor"a planned installation of such a device
for tfie™City of Lancaster, Pennsylvania, (2) as part of a system for the
treatment-disinfection of combined sewer overflow and pumping of the concen-
trated underflow back into the interceptor to the treatment plant. Removal
of grit, was intended to protect the wet well and pumping units of_this
proposed installation trom the eroding and siitation effects of solids Con-
centrations as high "as 13,000 mg/I~as well as reduce the effects of'depo.s-
tion in the downstream interceptor.
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A Inlet
B Deflector
C Weir and Weir Plate
D Spoiler
E Floor
F Conical Hopper
FIGURE 1 ISOMETRIC VIEW, SWIRL DEGRITTER
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SECTION III
DESCRIPTION OF THE TEST LAYOUT
The prototype swirl degritter installation at the Metropolitan Denser
Sewage Disposal District No. 1 treatment plant has two purposes: to ascer-
tain the grit removal efficiency of the test system, and to compare these
results with the grit removal performance b'f'tKe plant' s conventionalae'rated
grit chamber (AGC). The layout of the swirl"system, in~relation to the
pTant's aerated grit removal facilities has been planned to make these two
functions attainable. This installation is shown on Figure 2.
The 43.8 I/sec (1.0 mgd) swirl unit was constructed in 1974 at a cost
of $4,500 exclusive of pumps, valves and grit washer elements which were
readily available to the District. The cost of a comparison conventional
grit removal unit of the same design flow is approximately $57,500.
Sewage for the swirl degritter was pumped from the influent channel to
the AGC. The problem was to ascertain that the sewage delivered to the swirl
degritter contained the same grit as the sewage entering the AGC. Sampling
of the flow in the influent channel indicated that the solids were not evenly
distributed in the channel. A baffle plate was installed initially to pro-
duce turbulence but sampling indicated this did not provide an even distri-
bution of the grit and other suspended solids. An air header with six pre-
cision-type tubes was then installed and subsequent sampling indicated that
the solids distribution was satisfactory. This procedure of assuring uniform
concentrations of grit in the pumped sample reduced the settling efficiency
in the swirl degritter since the solids would normally enter the swirl de-
gritter as a stratified sewer load. The procedure did not affect the AGC
efficiency. As a. result both the evaluations of the swirl degritter and its
comparison with the AGC are relieved to be conservative.
The sewage was raised to a Parshall flume by two 15 cm ( 6 in-) self-
priming solids-handling pumps, each with a capacity of 78.8 1/s (1.8 mgd).
The suction hoses for the two pumps were located to pick up sewage at the
same point so that the use of either pump would obtain similar sewage
samples. The pumps delivered the sewage into a channel set about 1.83 m
(6 ft) above the ground, which discharged through a 22.8 cm (9 in ) Parshall
flume to measure the flow prior to entry into the swirl degritter. Grit
was discharged from the bottom of the swirl degritter into a standard grit
elevator apd-.yash.e'r and after sampling, was returned to the AGC. ETETGent
from the swirl degritter was also returned to the AGC after sampling.
Details of the swirl degritter are shown in Figures 3, 4 and 5. The
diameter selected was 1.8m (6 ft) and the other dimensions were chosen to
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Plant
Influent
Point for adding
sand (spiking)
Aerated
Influent
Channel
Aerated
Pump
Chasick
Sampler
No. 3
Parshall
Flume
Grit
Chambers
Effluent to
Primary Tanks
Swirl
Degritter
Chasick
Sampler
No. 2
FrGURE 2 LAYOUT FOR DENVER TESTS
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48.3cm
B
Inlet
Leg Position
.A —5-
I Outlet for Effluent to Chasick Sampler
J r
PLAN
FIGURES PLAN OF SWIRL DEGRITTER
7
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N
r-
C\l
<*?
(O
\~
0.64 cm (1/4 in) 0.-
30.5cm
0.32 cm (1/8 in) (j>
£
Spoiler
30.5 cm
(1ft)
10.48 cm (3/16 in)
1.22m (4 in)
2U5*""-" yn.'toag'
Opening
•MLeg
Stiffener
Typ. Ea. Leg
SECTION A-A
FIGURF4 SECTION A-A OF SWIRL DEGRHTER
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Effluent.
Outlet
25.4 cm (10 in) Flange
25.4 cm
(10 in)
40.6cm
(16 in)
30.5 cm (1 ft) Flange
~\ Inlet
I-
Outlet to Grit
Conveyor
and Washer
SECTION B-B
FIGURE 5 SECTION B-B OF SWIRL DEGRITTER
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agree with Figure 3 of the laboratory model study \£)J Excluding the volume
in the cone-shaped" hopper the detention time in the swirl degritter for var-
ious flows is shown in Table 1, based on the net volume in the main chamber
being 1,486 1 (52.5 cf).
TABLE 1. DETENTION TIMES
Flow
AGC
1/s mgd
438 10
876 20
1,952 40
2,190 50
Swirl Degritter
1-.8 m (6 ft)
1/s
21.9
43.8
87.6
131.4
mgd
0.5
1.0
2.0
3.0
Actual Detention Time
AGC^
mm
40
20
8
8
Swirl Degritter,
Tm.1.8 m (6 ft)
mm
1.1
0.6
0.3
0.2
Detention Time
Prototype Swirl,
Tp(2)
min
2.00
1.09
0.55
0.35
Note 1: Conventional design basis 3 to 4 minutes
2: From Froude number equation Tp = Qp1'5/Qnr'5(Tm) for swirl degritter
prototype flow of 438 to 2,190 I/sec (10 to 50 mgd)
The j-T-aiTgTjt-jjpri^c.npt-fi °£ Pipe used at the inlet was only two inlet"
diameters because the unit was constructed prior to completion of the laboi
atory studies. The recommended length as shown in reference (2) is three
The aerated grit chamber was designed to remove both grit and grease.
The initial design average flow was 876 1/s (20mgd) , based on a 20-minute
detention time. The unit was originally designed with a long detention time
to facilitate removal of grease. During the study tests, flows in the
aerated grit chamber approached 2,190 1/s (50 mgd), the detention time was
about eight minutes. The usual basis for design of aerated grit chambers
is to provide about three minutes detention time at peak flow. In a large
plant like Denver, where the peak flow may be two times average flow, the
detention time for average flow would be about six minutes.
In most cases, the rational design of grit chambers jg fragfri r»n -ro-
mqving particles over 0. 2TT""mm' or U.25 mm in size with s.g. ~nf 9.6S. U.S.
Standard Sieve number 70 has an opening of 0.21 mm. Little data are avail-
able on the percentage of grit removed in existing grit chambers over any
given size. It_ is common knowledge that grit over 0.20 mm in size is found
in plant units following p;1""**
It was considered necessary for purposes of this study to determine
the presence of grit over 0.20 mm in size in the influent and effluent
sewage of the aerated grit chamber and the swirl degritter. For this pur-
pose it was decided to use the model grit cyclone developed by A.H. Chasick
10
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60° x 3.8 cm (1-1/2 in) Deep
0.32 cm (1/8 in) <
Circular trough
5 cm (2 in) D.Pipe
a»~ Outlet
0.32 cm (1/8 in) 0
1.9 cm (3/4 in) Pipe
Outlets
3.8 cm (1-1/2 in)
Grit Outlet
3 — Steel Angle Legs
SECTION A-A
FIGURE 6 CHASICK GRIT SAMPLER
11
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and T.B. Burger (3), as a sampling device. This grit cyclone is shown in
Figure 6 and is referred to in
ments by Chasick and Burger indicated the percent recovery of various size
sands for various overflow rates.
Intially, in Denver, it was proposed to use and overflow rate of
814.6 m3/d/m'2 (20,000 gpd/sf) on the Chasick samplers, but this flow result-
ed in the deposition of so much grit that these units had to be emptied
every hour. Therefore the overflow rate was reduced to 407.3 nr/d/mr
(10,000 gpd/sf). This overflow rate is equivalent to an inlet flow of 1.38
1/s (21.8 gpm) . According to Chasick and Burger, (3) this overflow rate
should result in capJmning— 1QQ- nencenr— o-f— the grit larger than 0.20 mm in
the, Chasick sampler. Three Chasick samplers were installed as shown in
Figure 2: No. 1 to determine the grit in the influent to the plant, and
therefore to the AGC and the swirl degritter; No. 2 for the effluent from
the swirl degritter; and No. 3 for the effluent from the AGC. Gravity flow
was possible to Chasick samplers No. 1 and No. 2, but it was necessary to
pump up into Chasick sampler No. 3.
In the second series of tests, dry blasting sand, size 0.25' mm, was
added to the sewage after it was pumped from the influent channel. The
point where sand was added is shown if Figure 2. Because of the location of
the sand injector, only Chasick samplers Nos. 1 and 2 were effected by this
addition. Therefore, results from these two samplers could not be compared
to the test results from Chasick sampler No. 3 when the flow was- enriched
with sand. The process of sand addition is called spiking in this report.
12
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SECTION IV
EVALUATION OF TEST RESULTS
The first series of tests were established to evaluate flows of 43.8,
87.6 and 131.4 1/s (1.0, 2.0, and 3.0 mgd) in the swirl degritter. The
sampling points and proposed tests are shown in Table 2. The test run for
each flow was to be seven consecutive days. However, during the test run
for a flow of 131.4 1/s (3.0 mgd) the tests were interrupted for three days.
The results are shown in Tables A-l, A-2, and A-3 in the Appendix.
The data on grit removal for the first series of tests are shown in
Table 3. The weight of dry grit is converted to,_tha_Haieht_Qf grit ash_in
the table on l^ie'^asT^^r^SeHp^c&ci!P^Tr!v^at±le solids. The percentage
removal ot grjt~ash in the swirl degrittjer ranged trgnL.b^'.O to84. 2 percent,
with an average of 76.0 percent. The highestpercent ^^
the tilgftest fTowTatner than with the lowest flows, as might be expected.
IJItn^TiGi^rangea. from 86.8 to 92.7 percent with an average of
Therefore, on the average, the AGC perj£oj2iD£d^abJojit_liL_i>ejrcent
Becaits<
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TABLE 2. PROPOSED TESTS - FIRST SERIES—MAY 23 TO JUNE 21, 1975
Sample Point Grit Dry Grit Total Volatile Putres- Sieve
Volume Weight Solids Solids cibles Analysis
777
/o /o /o ^^^
Chasick # 1 Influent D D 2W
Chasick # 2 Swirl Effluent D D 2W
Chasick # 3 AGO Effluent D D 2W
Grit Swirl Concentrator Post-Wash D CW4 CW4 . SS WC
Grit Dorr-Oliver Classifier Discharge D CW4 CW4 SS WC
Notes:
Run 7 days each at Swirl flows of 43.8,87.6 and 131.41/s (1.0, 2.0 & 3.0 mgd)
D - daily total
2W - average of two samples/week
%
WC - weekly composite on dry grit (not ashed grit)
SS - single sample
CW4 - weekly composite of samples taken at 4 hour intervals
(continued)
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TABLE 2. (continued)
Ui
Sample Point
Grit Swirl Concentrator Pre-Wash
Grit Dorr-Oliver Classifier Influent
Aerated Channel #1 influent
Swirl Effluent
Aerated Grit Chamber (AGC) # 2 influent
Primary influent (AGC effluent)
Suspended
Solids
me/1
CW4
CW4
CW2
CW2
CW2F
CW2F
Volatile
Suspended
Solids
ma/1
CW4
CW4
CW2
CW2
CW2F
CW2F
BOD
COD
mg/1 me/1
CW2
CW2
CW2F CW2F
Notes:
CW4
CW2
CW2F -
weekly composite of samples at 4 hour intervals
weekly composite of 250 ml samples taken at 2 hour intervals
weekly composite of flow adjusted samples at 2 hour intervals
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TABLE 3. REMOVAL OF GRIT ASH—MAY 23 - JUNE 21, 1975
Ghasick Dry Grit Volatile Grit Ash Removal of Grit Ash Lbs of Kgs of
Sampler Lbs/Day (Kgs/Day) Solids Lbs/Day (Kgs/Day) %_^ Grit Ash / Grit Ash/
7° Swirl A.G.C. .Million . Million"
Gallons Liters
Flow; Swirl - 43.8 1/s (1.0 mgd); AGO - 2028 1/s (46.3 mgd)
1 Inflow 9.04 (4.1) 54.3 4.13 (1.87) 131 (16)
2 Swirl 2.13 (0.97) 53.1 1.00 (0.45) 75.8 31.8 (4)
3 AGC 0.74 (0.34) 59.2 0.30 (0.14) 92.7 9.6 (1.2)
Flow: Swirl - 87.6 1/s ;' (2.0 mgd); AGO - 2177 1/s (49.7 mgd)
£ 'l Inflow 8.14 (3.7) 20.8 6.45 (2.93) 205 (25)
2 Swirl 3.55 (1.6) 41.9 2.06 (0.93) 68.0 65.6 (8)
3 AGC 2.86 (1.3) 70.4 0.85 (0.4) 86.8 27.0 (3.2)
Flow; Swirl - 131.4 1/s (3.0 mgd); AGC - 2147 1/s (49.0 mgd)
1 Inflow 9.40 (4.3) 17.5 7.76 (3.5) 247 (30)
2 Swirl 3.17 (1.44) 61.4 1.22 (0.55) 84.2 38.8 (4.6)
3 AGC 2.33 (1.06) 66.9 0.77 (0.35) 90.0 24.5 (3.0)
Average % removal of grit ash:
Swirl 76.0
AGC 89.8
-------
The removal of dry grit is shown in Table 4. The removals in the swirl
concentrator ranged from 5.6,4 to 76.4_percenj:.|with an flYPT0"" nf Aft '' r°^~
cent. In the aerated grit chamber the^retnoval s ranged from 65.9 to 91.8
percent, with an average 03^/7.3 percent.In all three test runs the percent
removal in the aerated grit chamber was better than that accomplished in the
swirl degritter.
TABLE 4. REMOVAL OF DRY GRIT
MAY 23-JUNE 21, 1975
1.8m (6 ft)
Diameter
Swirl Flow
43.8 1/s
(1.0 mgd)
87.6 1/s
(2.0 mgd)
131.4 1/s
(3.0 mgd)
Average
% Removal Dry Grit
Swirl Aerated Grit
Degritter Chamber
76.4
56.4
66.3
66.4
91.8
64.9
75.2
77.3
7o Predicted
Swirl Efficiency
From Figure 47 (2)
Height
f or
Diameter*
97
78
71
Table 5 shows the removal of suspended and volatile solids for the
test period May 23 - June 21, 1975. Removals of suspended solids ranged
from 4.3Mto. 10-9 percent in the swirl depri|-f«J>V-''^omp'areci to i^.H to 29.6
percent in the aerated grit chamberT Removals of volatile solids ranged
from 3.0 to 9.8 percent in the swirl degritter. compared to 19.0 to 3TT.O
percent in the aerated grit chamber. """
Samples of washed grit were collected at four-hour intervals during
each seven-day test run. A sample of this seven-day composite was tested
for total suspended solids and volatile suspended solids. These results,
while not pertinent to this study, reflect a field test efficiency of the
grit washers. Sieve analyses were performed on samples of dried grit col-
lected from the Dorr-Oliver Classifier and the swirl unit elevator-washer
from the weekly composites. These indicated the relative size of the grit
removed by the two units.
The results are plotted in Figure 7, where the curves indicate the
coarsest grit was collected in the swirl degritter when the flow was lowest
17
-------
TABLE 5
REMOVAL OF SUSPENDED AND VOLATILE SOLIDS
MAY 23 - JUNE 21, 1975
Flow
in
Swirl
43.8 1/s
(1.0 mgd)
87.6 1/s
(2.0 mgd)
131.4 1/s
(3.0 mgd)
AV
Suspended Solids
Swirl
Influent
mg/1
266
233
219
239
Degritter
Effluent %
mg/1 Removal
248 6.7
223 4.3
195 10.9
222 7.1
Volatile
Swirl Degritter
43.8 1/s
(1.0 mgd)
87.6 1/s
(2.0 mgd)
131.4 1/s
(3.0 mgd)
AV
Influent
mg/1
199
184
173
185
Effluent %
mg/1 Removal
193 3.0
173 6.0
156 9.8
174 5.9
Aerated
Grit Chamber
Influent Effluent
mg/1 mg/1
249
239
209
232
Solids
Aerated
Influent
mg/1
184
194
160
179
184
194
147
175
7
10
Removal
26.1
18.8
29.6
24.6
Grit Chamber
Effluent
mg/1
143
157
112
137
%
Removal
22.2
19.0
30.0
23.5
18
-------
SIZE OPENING
INCHES
,3/4 I/I !/• 1/4 4 • • 10 It !•
U.S. STANDARD SIEVE NUMBERS
10 K» 40 BO 70 100
90
•0
70
•0
SO
40
30
20
K)
to.o
10.0
• 0 40
\\
\
\
\
©
©
\
I I
t.O 1.0 0 • 04
GRAIN SIZE IN MM.
o.t
1 Swirl @ I mgd
2 Dorr @ 46.3 mgd
3 Swirl @ 2 mgd
4 Dorr @ 49.7 mgd '
5 Swirl @ 3 mgd
6 Dorr @ 49.0 mgd
FIGURE 7 DENVER TESTS GRIT GRADATION CURVES
MAY 23-JUNE 21 FIRST SERIES
ao
•o
70
60
so
UJ
a:
UJ
40 U.
3*
30
20
10
0.1 0.06
_ FINE
6 R
AVE
L
COARSE 1 M
EBiU
S
y
A
N
1
D
r
IT
E
19
-------
at 43.8 1/s (1.0 mgd). The grit samples from the swirl at the two higher
flows showed almost identical gradation curves and indicated coarser grit
than that obtained from the aerated grit chamber. It should be noted that
the sieve analyses were carried out on dry grit which may have contained
considerable large-sized organic matter such as coffee grounds, seeds, corn,
and other material. The indication that the aerated grit chamber produces
finer grit may be due to the better washing and removal of organic matter
performed in the Dorr-Oliver Classifier than was performed by the screw
elevator and washer used in conjunction with the swirl concentrator. There-
fore, on the next series of tests the sieve analyses were carried out on grit
ash from the Ghasick sampler. It should also be noted that the recovery of
grit of less than 0.2 mm size was 10 percent or less. For this reason it was
decided to spike the second series of tests with fine sand.
The second series of test was limited to analyses of the contents of
the Chasick samplers. Each test run was limited to two hours and 20 test
runs were made with five each at flows in the swirl degritter of 21.9, 43.8,
87.6, and 131.4 1/s (0.5, 1.0, 2.0, and 3.0 mgd). The entire contents of
the samplers were collected for each run and tested as described in the
Appendix.
The second series investigation is described in Table 6.
To test the effectiveness of the swirl degritter in removing grit of
0.20 mm size, the flow to the swirl unit was spiked by. added blasting sand
during certain test runs. The spiking material was added just upstream of
the discharge point to Chasick sampler No. 1, as shown in Figure 2. About
22.7 kg (50 Ib) of sand were added during a one-hour period, beginning about
15 to 30 minutes after the two-hour test run. This quantity of sand, aver-
aged over the two-hour test run, is equivalent to adding 144 gm/m3, 7£ gm/m3,
36 gm/m3, and 24 gm/m3 (1,200, 600, 300, and 200 Ibs per rag) for the flows
of 21.9 1/s (0.5 mgd), 43.8 1/s (1.0 mgd), 87.6 1/s (2.0 mgd), and 131.4 1/s
(3.0 mgd), respectively.
The sieve analysis and gradation curve for the spiking sand is shown
in Figure 8.
The second series of tests were run from August 27-30, 1975. The test
results are shown in Tables A-4, A-5, A-6, and A-7 of the Appendix.
The efficiency of the swirl chamber in removing dry grit is shown in
Table 7.
No removals are shown for the AGC when the flow was spiked, since the
spiking only affected the grit collected in Chasick samplers Nos. 1 and 2
and not No. 3. Thus, only 8 of the 20 tests applied to AGC. The results
for the AGC ranged from a 51 percent reduction to a 132 percent increase in
grit.
This great variation in grit removal in the AGC is difficult to ex-
plain since, during the first series of tests, the removals for the seven-
day period were 91.8, 64.9, and 75.2 percent, with an average of 77.3 per-
20
-------
TABLE 6
PROPOSED TESTS SECOND SERIES
AUGUST 27 - 31, 1975
Sample Point
Chasick # 1
Chasick # 2
Chasick # 3
Inflow
Swirl
AGC
Grit
Volume
2H
2H
2H
Dry Grit
Weight
2H
2H
2H
Volatile
Solids
Z
SS
SS
SS
Sieve
Analysis
2C
2C
2C
Note:
Spiking
2H
SS
2C
Spike influent sewage with 0.25 mm sand at rate of 22.7 kg/hr *
(50 Ib/hr) if Chasick # 1 does not indicate 207. of 0.2 mm grit.
Total for two hour tests. Five tests each at flows of 21.9,
43.8, 87.6 and 131.4 1/s (0.5, 1.0, 2.0 and 3.0 mgd) in swirl.
Single sample from each two hour test.
On incinerated contents of two hour test or aliquot sample if
volume too great.
* GRIT
flow mgd
0.5
1
2
3
CONCENTRATIONS
Ibs/mg
2400
1200
600
400
gpm
288
144
72
48
21
-------
SIZE OPENING
INCHES
3/4
U.S. STANDARD SIEVE NUMBERS
100
•0
70
CO
50
40
30
20
10
0
20
I 1
1
1
.0 10.0 6
1
.0 4
1
0 2
^T U
0 1
—
••«.
0 0
1
•• •.
1
\
\
1
e o
\
\
\
1 1
\
\
\
4 0
I I
,
\
2 0
1
0.
100
90
SO
70
60
50
40
30
20
10
0
06
GRAIN SIZE IN MM.
Spike is dry blasting sand, 0.25 mm size.
SIEVE ANALYSIS
U.S. Sieve No. % Finer by Weight
100 11.4
GO 32.0
35 96.0
18 99.9
10 100.0
FIGURE 8 GRADATION CURVE OF SPIKING SAND
X
o
in
*
CO
o:
iii
FINE
GRAVEL
&6ARSE 1
MEDIUM 1
SAND
PINE
22
-------
TABLE 7. REMOVAL OF DRY GRIT
AUGUST 27-30, 1975
"" " ' •"• "••''
Flow Swirl
Degritter
21.9 1/s
(0.5 mgd)
43.8 1/s
(1.0 mgd)
87.6 1/s
(2.0 mgd)
Run
Number
1
2
3
4
5
AV
1
2
3
4
. 5
AV
1
2
3
4
5
AV
Percent Removal
Swirl Degritter
Normal Spiked
57
66
62
50
79
64
26
+50
+12
64
83
70
72
87
68
72
76
48
43
59
50
AGO
14
+127
+ 56
51
9
30
43
__
+132
+ 44
131.4 1/s
(3.0 mgd)
1
2
3
4
5
AV
8
24
16
+32
+46
41
+12
17
11
14
Note: Percent removed based on dry weight. Flow rate in the AGO was at
approximately 2,190 1/s (50 mgd).
cent, as shown in Table 4. Subsequent tests with the AGO at higher flow
rates showed a significant reduction in efficiency, as shown in Table 8.
The percent removals of dry grit from the swirl degritter were fairly
uniform for flows of 21.9 and 43.8 1/s (0.5 and 1.0 mgd) with removals rang-
ing from 50 to 87 percent. There was no marked difference in the removals
at .the top flow rates. However, the removals at the two higher flow rates
of 87.6 and 131.4 1/s (2.0 and 3.0 ragd) were erratic, with 3 of 10 test runs
showing an increase in grit. Here again, the results failed to agree with
23
-------
TABLE 8
REMOVAL OF GRIT ASH
AUGUST 27, 1975
Swirl Flow 21.9 I/a (0.5 mgd)
Run
No.
1
2
3
4
5
Note:
Ibs/mg
Chasick
Sampler
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
Average
Average
= Ibs/hr x
Grit
gr/hr
104
24
19
29
11
13
163
17
22
42
9
14
15
4
15
Spiked
Normal
764
Ash
Ibs/hr
0.229
0.053
0.042
0.063
0.024
0.028
0.358
0.037
0.049
0.093
0.019
0.031
0.034
0.009
0.033
7oRemoval of Grit Ash
3
Swirl AGO gr/m
21
76.8 5
S 4
58
61.9 2
55.6 3
33
89.7 3
S 4
9
79.6 2
S 3
3
73.5 1
2.9 3
82.0
67.7 29.2
Ibs per
Million
Gallons
175
40
32
48
18
21
274
28
37
71
14
24
26
7
25
S - Flow Spiked - not applicable
24
-------
the first series of tests which showed removals of 76.4, 56.4, and 66.3 per-
cent, as reported in Table 4. This may be due to removal by the higher flow
of grit deposited in the inlet conduit in previous runs.
The percent removals of dry grit are shown graphically in Figure 9.
This figure shows that only at the two lower flows did the swirl degritter
perform as well as in the first series of tests. The figure also shows the
erratic results obtained in the AGO.
The weight of dry grit collected in the Chasick samplers in the two-
hour test runs were converted to grams/nH (Ibs/mg), based on a constant flow
of 1.38 1/s (21.8 gpm) through the samplers. The results are shown graphi-
cally .in Figure 10. These curves show the effect of spiking on Chasick sam-
plers Nos. 1 and 2. Denver personnel reported that the point of spiking was
too close to the outlet point of Chasick sampler No. 1 and hence, the full
effect of spiking was not always felt by that sampler. This was most obvious
on August 20, 1975 when sampler No. 2 showed more grit in Runs 2 and 3 than
sampler No. 1. The figure also shows that the spiking had little effect on
sampler No. 3.
During the second series of tests the volatile solids in the various
grit samples ranged from 17.2 to 83.0 percent. Therefore, it was thought it
might be significant to work up data for the grit ash which would exclude the
effect of organic matter on the quantity of grit. These results are shown in
Tables 8 through 11. The percent removals are shown graphically in Figure
11. The results are similar to those for removal of dry grit except that the
large increase in grit for Run 5 on August 27 and August 29, 1975 for Chasick
sampler No. 3 have been changed to slight reductions, indicating that the
large increase was due to the collection of organic matter. The weight of
grit ash is shown graphically in Figure 12. This indicates a weight of grit
ash ranging from 2.39 to 55.1 kg/1,000 m3 (20 to 460 Ibs/mg) in the various
samplers. The results are similar to those shown for the dry grit except
that the weights are less.
In the second series of tests all material collected in the Chasick
samplers in each two-hour period was analyzed for volatile solids. Thus, it
is possible to compare the weight of volatile solids in the influent to the
plant to the volatile solids in the effluent from the swirl concentrator and
from the AGC. The ratio of these quantities is shown in Tables 12 through
16.
Table 13 indicates the results with flow of 21.9 1/s (0.5 mgd) in the
swirl concentrator and normal daily flow in the AGC. This indicates the
volatile solids in the effluent from the swirl has-5'1'percent of the volatile
solids in the influent. Thus 49 percent of the volatile solids were removed
with the grit. The data indicates that the effluent from the AGC had produced
..a volatile solids greater than 100 percent on each of the five two-hour tests.
This is no doubt due to sampling methods. The influent sample was taken from
the influent channel which was aerated to keep the solids in suspension. The
effluent sample was pumped from the effluent channel from the AGC with no
aeration. Possibly the pump suction was located near the bottom of the
channel where there was greater density of volatile solids.
25
-------
too
o
2
UJ
50
g .-..:.... so
UJ
LJ
.. g..ioo
150
D
RUN NO. |
DATE !
SWIRL FLOW; 21.9"i/s (0.5
,-0 !
- : Legend: |
O . ! Swirl Degritter
D ' (Aerated Grit Chamber
S ; Swirl Flow Spiked with Sand
. . . - ....
_
S , .J
i : 2 :
. AUG.
' :
. , .
.....
0
5 s: • • •
54, :5.
27 : : .
' . : ' ' i
: • :
. : - • ' '
- " .
'
, . !
, • .
' . , : ' ' i
' : ' ' I i '
. i ! i •
'••'. $.
1 2.1
\ AUG.
, • : •
. ' • .
i ' ' , ,
. . • ' '
• , |
:
, • i , :
I ' ! : , •
i . ' 'i T i ' '
• 'l ' I !
: : :s, . s
>'• 4 5
28:
.
, r
. ! , t
, - ,
1 ; !
i
= ; • i i ' ; ' :
' i : , : : '
. . . ! .
s i
12 J
AUG
,i
• i ! ' . ; '
• 1 . . . , .
. " - " ! :
. ' : ' ' '
! '
. i
'
I . ! •
; I
- • : • • ;Q-
: ! i ' ; '.
> s : : :
J 4.5
. 29 . • . : :
""'""•'""*'
• • 1 . •
' . ' i
' i :
• ; ,
: . t '
•
, t ', ;
! i i
-
: : : s: .s
i : \2' \ .1
'.'.'.' AUG
. ™.««n. ...... it—
t : :s : •
5. .4 : 5
.30 .
43.8 I/s Cl.Omgd)
87.6 I/s (2.0 mgd)
131.4 I/s (3.0 mgd)
FIGURE 9 REMOVAL OF DRY GRIT - AUGUST 1975
-------
o
o
o
lOO-i
so-
so.
40-
20-
.OJ
. 800 .
200
. 0
RUN NO.
DATE '
SWIRL FLOW
S S
234
AUG. 27
21.9 l/s (0.5 mgd)
Legend:
I S Run Spiked with Sand
i No. 1 Influent
| No. 2 Swirl Degritter Effluent
! No. 3 Aerated Grit Chamber Effluent
: S S S
.2 3 4
AUG..'29
43.8 l/s (1.0 mgd) 87.6 l/s (2.0 mgd)
FIGURE 10 WEIGHT OF DRY GRIT - AUGUST 1975
131.4 l/s (3.0 mgd)
-------
TABLE 9
REMOVAL OF GRIT ASH
AUGUST 28, 1975
Swirl Flow 43.8 1/s (1.0 mgd)
Run
No.
1
2
3
4
5
Chasick
Sampler
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
Grit
gr/hr
72
30
22
263
28
25
114
16
81
166
40
20
277
57
27
Ash
Ibs/hr
0.159
0.065
0.048
0.580
0.062
0.056
0.250
0.036
0.179
0.366
0.088
0.045
0.611
0.126
0.059
^Removal of Grit Ash
Swirl AGC gr/m3
15
58.9 6
69.6 4
53
89.3 6
S 5
23
85.6 3
28.4 16
34
76.0 8
S 4
56
79.4 ' 12
S 5
Ibs per
Million
Gallons
121
50
37
443
47
43
191
28
187
280
67
34
467
96
45
Average Spiked
Average Normal
Note:
Ibs/mg = Ibs/hr x 764
S - Flow Spiked - not applicable
81.6
72.2 49.0
28
-------
TABLE 10
REMOVAL OF GRIT ASH
AUGUST 29, 1975
Swirl Flow 87.6 1/s (2.0 mgd)
Run
No.
1
2
3
4
5
Chasick
Sampler
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
Grit
gr/hr
78
47
28
247
102
30
248
101
32
208
67
28
30
23
28
Ash
Ibs/hr
0.171
0.104
0.062
0.543
0.225
0.067
0.546
0.222
0.070
0.458
0.147
0.062
0.065
0.051
0.062
/^Removed of Grit Ash
Swirl AGC gr/m3
16
39.2 9
63.7 6
50
58.6 21
S 6
49
59.3 - 20
S 6
42
67.9 13
S 6
6
21.5 5
4.6 6
Ibs per
Million
Gallons
131
79
47
415
172
51
417
170
53
350
112
47
50
39
47
Average Spiked
Average Normal
Note:
Ibs/mg = Ibs/hr x 764
S - Flow Spiked - not applicable
61.9
30.4 34.2
29
-------
TABLE 11
REMOVAL OF GRIT ASH
AUGUST 30, 1975
Swirl Flow 131.4 1/s (3.0 mgd)
Run
No.
1
2
3
4
5
Chasick
Sampler
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
Average
Average
Grit
gr/hr
28
20
17
121
185
27
141
238
44
251
97
34
63
33
29
Spiked
Normal
Ash.
Ibs/hr
0.062
0.043
0.037
0.267
0.408
0.060
0.311
0.524
0.096
0.553
0.213
0.074
0.138
0.073
0.063
7oRemoval of Grit Ash
Swirl AGC gr/m3
6
30.6 4
40.3 3
24
+52.8 37
S 6
29
+68.5 48
S 9
51
61.5 20
S 7
12
47.1 6
54.3 6
+19.9
38.8 47.3
Ibs per
Million
Gallons
47
33
28
204
312
46
238
401
73
423
163
57
105
56
48
Note:
Ibs/mg = Ibs/hr x 764
S - Flow Spiked - not applicable
30
-------
Legend:
O Swirl Degritter
D Aerated Grit Chamber
S Swirl Flow Spiked with Sand
.••q-;-e-;'e!;
O , S> i O
RUN NO. I
DATE
SWIRL FLOW
• -g : • ;
'.2 . .3' 4 ]5
AUG!. 27 ::;
21.91/s (0.5 mgd)
3- :4 :.5'i;i:;.2,, 3 4;; 5
: :;: AUG. 28 .:
43.8 l/s (1.0 mgd)
I : AUG;. 29 . : i
87.6 l/s (2.0 mgd)
:: .AUG'.so ::::..
131.4 l/s (3.0 mgd)
FIGURE 11 REMOVAL OF GRIT ASH - AUGUST 1975
-------
kg/1000 m3 Ibs/mg
60-, 500
CO
NS
50-
40-
30-
20-
10-
400
RUN NO.
DATE
SWIRL FLOW:
Legend:
S Run Spiked with Sand
No. 1 Influent
No. 2 Swirl Degritter Effluent
No. 3 Aerated Grit Chamber
S S
2 34
AU6J27
21.9 l/s (0.5 mgd)
s : s s
2 3 : 4 ; |5
AUGJ29' '•:;;!!
87.6 l/s (2.0 mgd)
43.8 l/s (LOmgd)
FIGURE 12 WEIGHT OF GRIT ASH - AUGUST 1975
131.4 l/s (3.0 mgd)
-------
TABLE 12
REMOVAL OF VOLATILE SOLIDS
MAY 23 - JUNE 21, 1975
Ratio of
Test Chasick
No. #
Influent
1 Swirl
Effluent
Influent
2 Swirl
Effluent
Influent
3 Swirl
Effluent
Test
No.
1
2
3
1
2
3
1
2
3
1
2
3
Flow
Swirl
43.8
87.6
131.4
Dry Grit
Ibs/day
9.04
2.13
0.74
8.14
3.55
2.86
9.40
3.17
2.33
•
1/8 (1.0
I/a (2.0
1/s (3.0
Volatile Volatile Volatile Solids
Solids Solids Effluent To Influent
%
54.3
53.1
59.2
20.8
41.9
70.4
17.5
61.4
66.9
mgd)
mgd)
mgd)
Ibs/day Swirl
4.91
1.13 0.23
0.44
1.69
1.49 0.88
2.01
1.65
1.95 1.18
1.56
Flow
AGO
2028 1/s (46.3 mgd)
2177 1/s (49.7 mgd)
2147 1/s (49.0 mgd)
AGO
0.09
1.19
0.95
33
-------
Run
TABLE 13
REMOVAL OF VOLATILE SOLIDS
AUGUST 27, 1975
Ratio of
Chasick Dry
# Ib/hr
Influent
Swirl
Effluent
Influent
Swirl
Effluent
Influent
Swirl
Effluent
Influent
Swirl
Effluent
Influent
Swirl
Effluent
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
0.324
0.117
0.163
0.133
0.057
0.114
0.432
0.074
0.225
0.138
0.042
0.116
0.086
0.029
0.195
Volatile
Solids
% ,
29.2
54.5
74.5
52.6
57.3
75.5
17.2
49.4
78.2
32.6
54.7
73.0
60.9
67.9
83.0
Volatile Volatile Solids
Solids Effluent To Influent
Ib/hr Swirl
0.095
0.064 0.67
0.121
0.070
0.033 0.47
0.086
0.074
0.037 0.50
0.176
0.045
0.023 0.51
0.085
0.052
0.020 0.38
0.162
Total 2.53
Average 0.51
AGC
1.27
1.23
2.38
1.89
3.11
9.88
1.98
Notes:
Swirl Flow 21.9 1/s (0.5 mgd)
AGC = Asrated Grit Chamber
34
-------
TABLE 14
REMOVAL OF VOLATILE SOLIDS
AUGUST 28, 1975
Ratio of
Run
1
2
3
4
5
Chasick Dry
# Ib/hr
Influent
Swirl
Effluent
Influent
Swirl
Effluent
Influent
Swirl
Effluent
Influent
Swirl
Effluent
Influent
Swirl
Effluent
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
0.242
0.122
0.119
0.783
0.100
0.140
0.453
0.095
0.414
0.531
0.170
0.128
0.844
0.238
0.174
Volatile Volatile Volatile
Solids Solids Effluent
%
34.8
46.5
59.4
25.9
38.3
59.7
44.9
62.4
56.8
31.1
48.2
65.0
27.6
47.2
66.1
Ib/hr Swirl
0.084
0.057 0.68
0.071
0.203
0.038 0.19
0.084
0.203
0.059 0.29
0.235
0.165
0.082 0.50
0.083
0.233
0.112 0.48
0.115
Total 2.14
Average 0.43
Solids
To Influent
AGC
0.85
0.41
1.16
0.50
0.50
3.42
0.68
Notes:
Swirl Flow 43.8 1/s (1.0 mgd)
AGC = Aerated Grit Chamber
35
-------
Run
TABLE 15
REMOVAL OF VOLATILE SOLIDS
AUGUST 29, 1975
Ratio of
Chasick Dry
f Ib/hr
Influent
Swirl
Effluent
Influent
Swirl
Effluent
Influent
Swirl
Effluent
Influent
Swirl
Effluent
Influent
Swirl
Effluent
•
•
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
0.305
0.226
0.175
0.693
0.361
0.230
0.686
0.392
0.241
0.579
0.236
0.221
0.109
0.164
0.253
Volatile Volatile Volatile
Solids Solids Effluent
% Ib/hr Swirl
43.8
54.0
64.6
21.6
37.6
70.9
20.4
43.4
70.8
20.9
37.9
71.9
40.5
68.8
75.5
0.134
0.122 0.91
0.113
0.150
0.136 0.91
0.163
0.140
0.170 1.21
0.171
0.121
0.089 0.74
0.159
0.044
0.113 2.57
0.191
Total, 6.34
Average 1.27
Solids
To Influent
AGC
0.84
1.09
1.22
1.31
4.34
8.80
1.76
Notes:
Swirl Flow 87.6 1/s (2.0 mgd)
AGC = Aerated Grit Chamber
36
-------
Run
TABLE 16
REMOVAL OF VOLATILE SOLIDS
AUGUST 30, 1975
Chasick Dry
Ratio of
Volatile Volatile Volatile Solids
1
2
3
4
5
Not
Influent
Swirl
Effluent
Influent
Swirl
Effluent
Influent
Swirl
Effluent
Influent
Swirl
Effluent
Influent
Swirl
Effluent
es:
#
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
Ib/hr
0.141
0.129
0.117
0.393
0.519
0.202
0.443
0.645
0.271
0.739
0.436
0.279
0.248
0.187
0.221
Solids
55.9
66.8
68.2
32.0
21.4
70.1
29.8
18.7
64.5
25.2
51.2
73.4
44.3
60.9
71.4
Solids
#/hr
0.079
0.086
0.080
0.126
0.111
0.142
0.132
0.121
0.175
0.186
0.223
0.205
0.110
0.114
0.157
Total
Average
Effluent To Influent
Swirl AGC
1.09
1.01
0.88
1.13
0.92
1.33
1.20
1.10
1.04
1.44
5.13 6.01
1.03 • 1.20
Swirl Flow 131.4 1/s (3.0 mgd)
AGC = Aerated Grit Chamber
37
-------
Table 14 shows the results with flow of 43.8 1/s (1.0 mgd) in the swirl
These results show the average remaining percentage of volatile solids is 43
percent for the swirl and 68 percent for the AGC. Both results appear reas-
onable.
Table 15 shows the results for flow of 87.6 1/s (2.0 mgd) in the swirl.
The remaining percentage of volatile solids is 127 percent for the swirl and
176 percent for the AGC. If the results for Run No. 5 are deleted, the per-
centates are 94 for the swirl and 111 for the AGC, which would be reasonable.
Obviously as the flow in the swirl increases the percentage of volatile
solids retained in the swirl decreases.
Table 16 shows the results with a flow of 131.4 1/s (3.0 mgd) in the
swirl. The remaining percentage of volatile solids are 103 percent in the
swirl and 120 percent in the AGC. These results appear reasonable if allow-
ance is made for sampling errors:
The foregoing would indicate that at flows up to 43.8 1/s (3.0 mgd) up
to_J>0__Bercent of the L volat_il^_SQljxls_wjJJ;_^be__removed by the swirl concentra^
Thereforethegr^tremoval mechanism must be TeTected so tnaTTTie^rit
jL_tjiflaiijS^ZSa33I!S3Z3E!!^^
nj^cJiflHB£l . At flows ot 8^.5 T7sQ270i^3n^n^^reaFer™1ajnr the
volatile solids appear to pass through the swirl concentrator. The above
results are considered reliable because flow from the influent and effluent
channels to the Chasick sampler was by the gravity in both cases.
The results for the AGC are not considered reliable because the sample
from the effluent channel to Chasick sampler No. 3 was pumped. Possibly the
pump intake line was located near the bottom of the channel where the den-
sity of volatile solids were greater. Aeration was not provided at this^
sampling point as was at the point in influent channel from which the in-
fluent sample was pumped.
After ignition of the dry grit for determination of volatile solids,
the ashed grit in its entirety was sieve-analyzed. The data from the sieve
analyses are shown in Tables A-4 through A-7 in the Appendix. The sieve
analyses for the three grit samples from each test run are shown graphically
on Figures 13 through 32. These gradation curves are discussed below for
each of the 4 flows through the swirl degritter. ^ ---- ^x
A. Gradation curves for a swirl flow of 21.9 1/p (0.5 mgdV/
• With spiking — ^Figures 13, 15 and 16. These figures are
similar. Due to spiking with fine sand, the grit in the
influent is finer than the grit from the AGC which did not
receive spiking sand. The grit from the swirl concentrator
is as in the case without spiking, finer than that in the
spiked plant influent.
• Without spiking — Figures 14 and 17. These 2 figures are
similar. They indicate that influent grit is coarsest,
AGC is medium-sized, and the swirl grit is finest.
38
-------
than the AGCs.
Bo Gradation curves for swirl flow of 43.8 1/s (1.0 mgd);
• Without spiking—Figures 18 and 20. The swirl grit is
coarser than in Figures 14 and 17 and is still finer than
the AGC grit. The influent and AGO grit vary considerably
between Figures 18 and 20. In Figure 20 the 2 have similar
gradation whereas in Figure 18 the influent grit is much
coarser and the grit chamber is much finer.
• With spiking—Figures 19, 21 and 22. These curves show
the effect of spiking on the influent grit which is finer
than without spiking. However, the swirl grit remains
about the same as without spiking. The AGC is about the
same in Figure 22 as in Figure 18 and is finer than the
influent grit. In figures 19 and 21 the AGC is coarser
than in Figure 22 and is coarser than influenj^erit.
(1.0 mgd):
Gradation Curves for swirl flow of 87.6 1/s
• Without spiking—Figures 23 and 27. These curves show
a definite change from Figure 18. The gradation for the
influent grit and the AGC is similar to Figure 18. How-
ever, in both Figures 23 and 17 the gradation of the
swirl grit is not greatly different from the influent
grit and the grit from the grit chamber is the finest
grit. This would indicate that at some point between a
flow of 43.8 1/s (1.0 mgd) and 87.6 1/s (2.0 mgd) the .
swirl degritter ceases to produce a grit as fine as that
from the AGC.
• With spiking--Figures 24, 25 and 26. Figures 25 and 26
exhibit influent grit similar to Figurese 23 and 27
which are without spiking. The laboratory personnel at
Denver felt that sometimes during the tests the point of
spiking was too close to the inlet to Chasick sampler No. 1
to impose the full effect of the spiking on that sampler.
This condition seemed to prevail in Figures 25 and 26. The
grit from the swirl is finer than the grit from the AGC,
indicating that the spiking may have less effect on the
influent as the swirl. •—••-•••••-^••-••^•i ^
gradation curves for swirl flow of 131.4 1/s (3.0 mgd);
• Without spiking—Figures 28 and-32. These curves indicate
that the swirl grit is about the same as, or a little
finer than, the influent grit and in both cases much
coarser than the AGC grit shown in Figures 23 and 27.
• With spiking--Figures 29, 30 and 31. Figures 29 and 30
39
-------
are the same for influent and swirl grit, both showing
the effect of spiking and both indicating the same
gradation. For some reason, the AGC grit is much
coarser than the other grit in Figure 30 and much finer
than the other grit in Figure 29 . In Figure 31 the AGC
grit lies between the 2 gradation curves shown in
Figures 29 and 30.
In summary, the grit from the swirl is finer than the AGC grit for
flows through the swirl of 21.9 1/s (0.5 mgd) and 43.8 1/s (1.0 mgd) . At
swirl flow of 87.6 1/s (2.0 mgd), without spiking, the swirl grit gradation
is about the same as influent grit and coarser than AGC grit. With spiked
flow, the same holds true for 2 out of 3 runs.
At a swirl flow of 131.4 1/s (3.0 mgd) for unspiked influent the
gradation of the influent grit and the swirl grit is similar but coarser
than the AGC grit. For spiked flow, the swirl and influent grit have the
same gradation in all three cases. Compared to the AGC grit the swirl and
influent grit is finer in one case and coarser in another.
While the swirl degrit|ter_-j^suJJiS--O^e^alJnmw£re i lower than' predicted
by the LaSarTe™mo3ejniyaraulic tests for the higher flow rates oro/^^J^s
(2.0 mgd) and 131.4 1/s (3.0 mgd), at an average flow of 43.8 1/s (1.0 mgd)
theregul^jjgBarfflfld • Ifc was suspected that the AGC, like the swirl unit,
al^owould not operate at rated efficiencies for the high rates of flow of
2 and 3 times average flow. These tests were conducted on April 29 and 30,
1976, and were restricted to measuring the efficiency of the AGC only, using
Chasick samplers Nos. 1 and 3 as shown in Figure 2. The actual data is pre-
sented in Table A-8.
The efficiencies were calculated only for those runs where applicable,
and are presented in Table 17. Where the volume of grit in the effluent
exceeds the volume of the influent, no efficiency figure is reported. Only
in the last two runs does the data show a removal of the grit by the AGC.
It is obvious from these data that there is a significant reduction in grit
removal when flows exceed design limits regardless of the grit removal
method used.
ESTIMATED COSTS
General
For comparative purposes estimates were made of construction and
annual operation costs of the swirl concentrator as a grit separator and
the standard aerated grit chamber. Estimates were made for three sizes of
each type for average flows of 43.8, 131.4 and 438 1/s (1, 3 and 10 mgd).
Present worth was determined for each size and type based on a 20-year
period and 6-1/8 percent interest rate.
Swirl Degritter
The size of the swirl concentrator was based on data given in The
40
-------
Swirl Flow 214 l/i (OSmgd)
SpOudwHhGrit
U.S. STANDARD SIEVE NUUICftS
» l« •• M 10 40 *> TO too MO
SwW Flow 21.9 l/i OS mpj|
Spiked with Grit
1 1 — [T
[1™" ' JTB"
IN
A
N
\
• M
K
K
\
\
0
^
\
\
] — i
\
\
\
\
\
— ' — T
\
\
\
\
\
0
ChHidc
No. 1 Inrkwnt
Ho.2 SwW D*rin»* Efnwtnt
Ho. 3 Aw«**d Odt Chwntwr Effluwn
FIGURE 13 GRIT GRADATION CURVES-
RUN NO. 1 AUGUST^?, 1975
IHCMCS
Ml M M M 4 •
1
I*
1
1
r
"s
H— L;
\
s
w
*
V
s
-']
1
\
v
V
V
"*^
\
\
\
\
\
\
\
\
109
to
»-
TO »
M
*
•0
>
•
w
*
40 •-
/
10
to
10
0
• MAIN SIZC IN MM
8 RAVEL
SAND
No. 1 InfliMM
No. 2 Swirl Dtyiror Effliwnt
Mo. 3 AMfttd Grit Chamfer EHIuwil
FIGURE 15 GRIT GRADATION CURVES
RUN NO. 3 AUGUST 27, 1975
Swir
SIZE OPEMlNt u.S
INCHES
M Wl M IM 4 • Ik
t 1
1
!
1
• WJ •
0
ttRAVEL
1
Flow 21 9 t/i (05mgd)
S It 1* tO M 40 •« TO
-^
x
^i
40 tO 10
• RAIN SIZE IN
KH
X
s
\
• • e
MM
SAND
\
\
^
,
\
\
* 0 J •
•oa MO no
I |
V
\
\
\ ,
'
1 Ot
T
00
Swirl Flow 21.9 l/i (0.5m»J|
Sp«k*d with Grit
Chwkk
No. 1 tntliwnt
No. 2 Swkl D^-itttf EH1o*m
No.3---.- AwatwlGmChunUr
FIGURE 14 GRIT GRADATION CURVES
RUN NO. 2 AUGUST 27, 1975
1
1
'
o no *o 4
6 RAVEL
4*,
^T-
0 1
<
-~»ti
1 >
~~C
ss^
•-
\
s
0 to 0.0
S A N 0
^.
V
\
\
\
\
\
1 1
\
\
\
\
\
\
\
T
1 riNi
Legend:
Chi tick
No. 1 InlKiiftt
No. 2 Swirl D*oritt«r EKIumt
No. 3 A*r«t«d Gtit Chimbtr Elfluint
FIGURE 16 GRIT GRADATION CURVES
RUN NO. 4 AUGUST 27,1975
41
-------
S*nl Flow 21 9 l/i ID.Snigdl
SwM Flow43.8 I/I 11.0 mfdl
tpiMwiOiGnt
SIZE OPENIH*
mews
i r-iT
;
o *a
TTT
0
1
0
u.s
1
1 1 1
\
0 1 9
i
IT
s
00
•x
s
k
«
s
s
4 0
1 — 1
\
\
v
\
\
a 0
.00 HO 1
1 1
\
\
\
\
\
\
\
i fli
u
to
w
*
__«"*.
- _ H
W
*
0
00»
I f.kt I tiUU I UtBIUU I HffT-
ORAVtLSAND
1121 OPlm
mews
r i i
!
t
t
i
I
i '
TH
HI
>
SL
1
\
s
\
\
\
\
v,
\
^
\
\
iOO MO 1
\
V.
\
\
F ""
•MAIN SIZE IK MM
FINE I CO»BH
I - " ' ** *
»IZt III DM
• RAVEL
miam* - J
mi eniiiM
I»CMC$
IM I/I M v
'
01 II. II
N« »*
U.S. STAMOAMD SIEVE NUUIEMS
(•» « • • «0 it t4 t» »0 40HT»>40>4a>
' ' 1
*-*
""•*. ' '
\'
^
! ' '
"ll
.
S^i
\
X
^\
\
\
\
s\
\
\
\
N
\
\
* M
- TO *
«J
*
W
X
X
o.o«
-
SAND
Li«>nd:
Chnicfc
Mo.1
No.2 Swill D
Bo. 3 AomodGrltChonrtOfEHIiim
FIGURE 18 GRIT GRADATION CURVES
RUN NO. 1 AUGUST 28, 1975
No.1 Influtm
No. 2 SwM Otyltur Eftlu«nt
No. 3 - • - - - Aw«ttd Qrlt Chimbtf Erfhrnrt
FIGURE 20 GRJT GRADATION CURVES
RUN NO. 3 AUGUST 28, 1975
42
-------
!
.00
•0
•0
TO
• 0
•0
10
10
0
1C
L»
Ch
N
N
N.
F
,«
•0
to
to
10
•o
4O
to
M
O
1
L«S
Chi
Nr
ize opium*
IHCHCt
r
[. -f_|_
t
i
!
— iif-.
i
i
o na
S
!
U.I
j ^4
j
;
:
i ! 8
.
-4 - — ^ 1
vnri f tow 43.8 l/t 1 0 r
piktdwithGiit
^>f4
•-1
j
:
1 ,
1
nod)
HUUSCRS ,
71-^,
m
;
.
i\
\
\
\
\
\
\_
s
X
\
\
\
\
\
•0 40 to ro 0« 040) 01 Ol
Swift Flow 17.6 IV. (iO mtdl
Size OKIHHS U.S. STANDARD SICVC HUUSCRS
M IMCHCS
- - M
' ~ *° M
. - to *
w •
»
- - *° M
•
, «0 _
W
*
_ _ «0 U. ^
«e
- - » »o
- - *° to
- - I0
- - ° .
1 '
•" m. 2T
GRAVEL SAND
send:
lie* L«gt
9. 1 Influent Chnfa
9. 2 Swirl D«griRw EHIu.nt No.
9. 3 A«fl1*d Gilt Chimtef EHIutnt No.
IGURE21 GRIT GRADATION CURVES Fl
RUN NO. 4 AUGUST 28, 1975
Swirl Flow 43.1 l/i (1 J) mfd)
SpikwJ with Grit
S1ZC OKNIHS U.S. STANDAPIO StCVC NUMSCflS
IHCHCS v
M Vt Ml 1/4 « • •MltMt»M40MTO«60l40M»MB >u)
00 »O
GRAVEL
' r^
i 1
I "T '
§>:•-
"'s
GRAIN SiZC
v».
\
'
>v
\
^
\
\
"\
\
\
1 1
\
\
\
IM UH
SAND
. - re * «
M
»
>
W
•
*
. - M "
. - «> «•
0 •
AIIAVC
nd:
dk
1 i
3 /
GURE
1
e
1
^
^;
x' '
sx
s.
'
4* •• 1 •
SRAtH SIZC
\ \
\
1
\
\
s
s,
\
1
\
\
\s
\
1 '
\
\
\
\^
\
IM MM.
L | SAND
nflwwit
.wlrl DwfttK Etflwnt
Uratvl Crh Ch*r*«* EffluMt
23 GRIT GRADATION CUR\
RUN NO. 1 AUGUST 29,
Swirl Flow 873 l/t (2.0 rrvD
Spllud with Orit
U.S. STAHOARD SICVC KUMBCRS
1
*^
^
S8Ws'
' ^
^
^ S •
'
S
\
\
V
y
I
'
\
V
\
1
\
'
\
\
\
\
\
\x
f
'5
H
»
S
• • " *
H
*
*
•«•
rES
1975
*
OM ••• »» ' •» 40 1* 10 »-« »4 0.1 «t *.! C.M
•RAIN SIZC IK MM.
«"AVEL | SAND
Wnd: . Logtnd:
uck Outlet
.
No. 2 Swill D«siiK«r EHIumt
No. 3 - • - • - A«r«t«d Gut Chimtxr Ellliwrn
No.l S«H Dwftttr EHteM
No. 3 A«nt«l Grit Chamtor EfflMMt
FIGURE 22 GRIT GRADATION CURVES
RUN NO. 5 AUGUST 28, 1975
FIGURE 24 GRIT GRADATION CURVES
RUN NO. 2 AUGUST 29,1975
43
-------
,«
H
M
TO
4O
to
*O
10
to
»
LO{
Ch
N
r*
N
Fl
i
«.»
••
M
to
>t
t
a
Li
Ch
MriFk>»t7.« I/I (2.0 mfdl . Sw
SplM with Slit
IIZC OnNIIMJ U.S. STANOAIIO SICVC NUMtCHS ^INCHcY"1* "'*
1 -' ' i
j
,
ao n.o
G RAVEL
lend:
itch
i
H
s^
j
•*— M..1
X , '
\'H
\
^
S
.
'
I"V
i \
'K
K
i
i
i
\
\
\N
\'
\
\
\
1 p
;\
\
\
\
\
.
\
0 0 10 10 0*040)01 1
CHAIN SIZE IN UH
SAND
»
M
_ _ « •
1 1 I j
i
004 H* *t
\
N.
N
4
rtFkw 87.6 l/t (2.0 mod)
i it i« to to w H r« ioa MO aoo M
'-^-'4,
\
\\
NA
s
MAIN SIZC
^
y
\
\
\
\
IN MM.
s
\
\
\
>
^
%
\
\
\
>
V
\
\
\
CRAVE L SAND
O-
"°58S!8S38!
Legtnd:
Ctlnktc
il"." sisffisrii..-, £'"-" E-Kre.ru-
GURE25 GRIT GRADATION CURVES FIGURE 27 GRIT GRADATION CURVE
RUN NO. 3 AUGUST 29, 1975 RUN NO. 5 AUGUST 29, 19
Sw1r1Flow«7JJI/.!2JJmtd) Sw.rt Flo* 131.41ft lOmodt
Splk«S with Grit
•» trf M W
• • *•
1 F 1 HC
Q RAVEL
14 t
f~ "^G
^
V
N
V
~ ~>
\
\ \
\
00 .O 0 •
flRAIN IIZC IN MM.
\
V'
\
\
1
v\
'\
\
M MO •
^
'\\
V
\
\
4 0 > o'l 1
| CO*R5I I Ml&tUw 1 rme
SAND
g
•0
M
TO
to
_ _ 10
40
40 k.
*
10
M
004
D* «b»
L... ' I N|
0 4
X,
\
i
N
\
1 |
sN
N\
\ '
<
>s
'
s
v>
^
* 10 10 04 ft
OKAItt SIZC IN MM
:OARK MEDIUM
s
^N
\
\
\
\
\
\
\
4 0.* 0* ft'l
PINK
*
S
75
•00
•0
•0
1-
TO X
9
M
»
to
>
m
» .
• w
•
40 h.
/
w
to
»
o«
,0 ".AVtL SAND
S*"* 'Leg*"*
nick 'Chwkfc
.
No.: SriH DwWir EHImM
No.3 Ant«lGltt« ENIum
No.3 tanudOrhOumoir EHImM
FIGURE 26 GRIT GRADATION CURVES
RUN NO. 4 AUGUST 29, 1975
FIGURE 28 GRIT GRADATION CURVES
RUN NO. 1 AUGUST 30, 1975
44
-------
MrlFkm 131.4 I/I (3.0 mtdl Sri
sound Mm odt in
tin onmm u.t. STANOIKD titvt HUMMM ,|Zl OPIUM u.l
i»cnct iNcms
j
•00 AO
GRAVEL
-r T
BE
-^ I
-
• »IN SIZE IN
-.
s \
^
'\
\\
V
1
^
\
\\
\
\
\
MM
SAND
- *° 40
_ _ 40 kk w
/
- - «° to
1 '
1
i
O-M m» •*
'
4D 4
Q RAVEL
1^
**i«*
rl Flow 131^4 l/i 13.0 mgd)
c*d with Grit
M
K'
s
^
L\
\
\
0 10 10 Oft 0
• MAIN SIZE IN MM
^
\\
\
\
\
N
\
\
\
\
V
V
\
\
\
\
\
\
4 01 01 01
SAND '
oc
Ugend:
OlMJCfc
No.1 InlltMnt
No. 2 S..I Ckgnttii EHIutnt
No. 3 A«wl Gilt Chinnlm Elfltwnt
FIGURE 29 GRIT GRADATION CURVES
RUN NO. 2 AUGUST 30,1975
Lvgend:
Chitidc
Ho. 1 Influent
No. 2 Swirl D*?itt«( Efflu*nt
Mo. 3 A«f»tfd Gilt dumb* Efflu.ot
FIGURE 31 GRIT GRADATION CURVES
RUN NO. 4 AUGUST 30,1975
Mri Flow 131.4 tMUlivil
S»irl Flow 131.4VlUOmgdl
M MM*
•>• «M
• RAVC
•V-md:
uwiek
10-1
I I
a
r-f
t
•
1 M
BC
s.
(."I '
\
\
* •
MAIN «1Zt
s
\
•4
IN HI
A N
1
\
\
•
.
D
V
\\
\
* a
1
V
v\
\
•
^
\\
\
* •->
- . 4»
•0
_ _ N)
0-04
I B II !• 10 tO 40 tO TQ IQQ K)
.
No. 2 Swirl Dorlrnr Effluont
So. 3 '
FIGURE 30 GRIT GRADATION CURVES
RUN NO. 3 AUGUST 30, 1975
. 1 i
:
j
i
,
J
"4
— • .». ,
**«xi
\ '•
\.
1sv
'}
' i
XN
|
i
^
\
^
N
\
\
s
\
\
\
S
\
1 1
!
\
\
\
\
• RAIN SIZC IN
0 RAVEL
I CQAtt^ET I MfDiyM
Lvgond:
Chtiick
No. 1 InfliMnt
No. 2 Swirl D*grttttr EHIu*nt
No. 3 Atrttwl Girt Chwnbtf Efflutnl
FIGURE 32 GRIT GRADATION CURVES
RUN NO. 5 AUGUST 30,1975
45
-------
TABLE 17
AERATED GRIT CHAMBER
SINGLE CHAMBER HIGH PLOW EFFICIENCY
Influent Effluent
Date
4/28/76
4/29/76
4/30/76
Time Total
AGC
Flow-mgd
7
9
10
12
8
9
10
11
12
8
9
:30 am
:30 am
:30 am
:30 pm
:00 am
:00 am
:00 am
:00 am
:00 am
:00 am
:00 am
35
58
70
69
22.3
36.5
62
61
68
23.5
36
Sampler # 1 Grit Sampler f 3 Grit Effi-
Volume Volume ciency
Flow-apm Quarts 'Flow-gpm Quarts %
21.
21.
21.
21.
21.
21.
21.
21.
21.
8
8
8
8
8
8
8
8
8
21.8
21.8
2.25 21
21
21
2.0 21
21
21
2.0 .21
21
3.75
21
2.0 21
.8 2.5 —
.8
.8
.8 2.25 —
.8
.8
.8 2.0
.8
3.5 6.7
.8
.8 1.75 12*5
46
-------
^, g 3^0
-------
/)
4) -*<•*
-------
Swirl Concentrator as a Grit Separator Device (2). The principal diameter
of the chamber, D2 was obtained from Figure 13, Chamber Diameters for 90
Percent Recovery and RI/DI =2 (2), using a ratio of % to D2 of 0.333. The
remaining dimensions were obtained from Figure 3, General Design Dimensions
(2). The derived dimensions are as follows:
Average Flow 43.8 1/s 131.4 1/s 438 1/s
(1 mgd) (3 mgd) (10 mgd)
D 1.83 m 2.44 m 4.27 m
(6.0 ft) (8.0 ft) (14.0 ft)
D & D 0.30 m 0.40 m 0.71 m
(1.0 ft) (1.33 ft) (2.33 ft)
D 1.22m 1.62m ^J. ^iHnu^ 2.1*5 «H
J (4.0 ft) (5.33 ft) U4.67 ft)
H 0.61 m 0.81 m 1.42 m
1 (2.0 ft) (2.67 ft) (4.67 ft)
H 0.08 m 0.10 m 0.17 m
(0.025 ft) (0.33 ft) (0.58 ft)
H min 0.30 m 0.40 m
J (1.0 ft) (1.33.ft)
The type unit used for estimate purposes was similar to that shown in
Figure 9, Grit Chamber Below Ground with Inclined Screw Conveyor (2) with
following revisions: (1) the exterior wall of the grit separator was assum-
ed to be of concrete with a vertical exterior face, (2) a horizontal passage
through the concrete assumed to provide access for lubricating the bottom
fitting of the inclined screw conveyor and (3) a manhole, 0.91 m (3.0 ft)
square, was provided to give access to the bottom fitting of the screw
conveyor.
Aerated Grit Chamber
The aerated grit chamber was sized to provide a detention period of 3
minutes at the maximum rate of flow. Peak flow factors were based on Fig-
ure 4 in American Society Civil Engineers Manual No. 37 (4). The resultant
dimensions are as follows:
Average Flow 43.8 1/s 131.4 1/s 438 1/s
(1 mgd) (3 mgd) (10 mgd)
Peak "flow factor 3.0 2.5 2.0
Maximum flow 131.4 1/s 328.5 1/s 876 1/s
(3 mgd) (7.5 mgd) (20.0 mgd)
Required volume 23.6 cu m 59.2 cu m 157-9 cu m
(835 cf) (2090 cf) (5,560 cf)
47
-------
2.44 m
(8.0 ft)
2.29 m
(7.5 ft)
4.27 m
(14.0 ft)
23.65 cu m
(835 cf)
3.05 m
(10.0 ft)
3.05 m
(10.0 ft)
6.41 m
(21.0 ft)
59.08 cu m
(2085 ct)
3.66 m
(12.0 ft)
4.27 m
(14.0 ft)
10.06 m
(33.0 ft)
157.09 cu m
(,544 cf)
Selected depth
Selected width
Selected length
Selected volume
Construction Costs
Cost estimates of the swirl concentrator as a grit separator device
were made for two purposes: (1) to indicate the probable construction cost
of the facility; and (2) to compare its cost with that of a conventional
aerated grit chamber.
The cost estimates are considered to be reasonable engineer's estimates
However, during periods of economic inflation, it is not unusual for contrac-
tor's bids to materially exceed engineers' estimates.
Cost Basis
The costs are based on the following:
a. EngineeringNews Record Construction Cost Index average
for U.S. is 2,500
b. Unit prices as follows:
Steel Sheet Piling $108/sq m $10/ sq ft
(for temporary use during construction)
Excavation $ 18/cu m $14/cy
Reinforced Concrete $392/cu m $300/cy
c. Contingent and engineering costs are assumed to be 35
percent of the foregoing items.
The swirl separator dimensions are derived in the previous section.
It is assumed that the ground surface is 0.61 m (2 ft) above the jsrown^of
the inlet pipe and the tapofmt3!nk^^.^^^m^T^?Tr^^o!vem^fie crown ot the
inlet pipe, this will provide 0.61 m (2 ft) of freeboard above the weir.
The conventional aerated grit chamber is set to provide a freeboard
0.46 m (1.5 ft) with a top of wall 0.30 m (1 ft) above ground surface.
The following assumptions are made for both structures:
a. Excavation is all earth. The unit price includes cost
for backfilling and crushed stone under the structures.
48
-------
b. Temporary steel sheet piling is required 0.61 m (2 ft)
outside the exterior walls of the structures. Sheet-
ing assumed to extend 0.61 m (2 ft) below lowest point
of excavation and 0.30 m (1 ft) above the existing
ground elevation.
c. Equipment costs for the aerated grit chamber include the
cost of bucket elevator, screw conveyor, transverse
baffle, diffuser piping, motors, and electrical work.
d. Miscellaneous costs for the aerated grit chamber include
the cost of the longitudinal and effluent baffles, com-
pressors, slide gates, baffle supports, and grating for
by-pass channel.
e. Equipment costs for the swirl concentrator include the
cost of a grit wash screw.
f. Miscellaneous costs for the swirl separator includes the
cost of piping skirt, weirs and plates.
Cost of Swirl Separator as a Grit Separator
The estimated construction cost of a swirl separator with a capacity
of 43.8 1/s (1.0 mgd) is $47,000, for 131.4 1/s (3.0 mgd), $57,000, and for
438 1/s (10.0 mgd), $69,000. The breakdown of these costs is shown in
Table 18.
Cost of Conventional Aerated Grit Chamber
The estimated construction costs of a conventional aerated grit chamber
with a capacity of 43.8 1/s (1.0 mgd) is $69,885, for 131.4 1/s (3.0 mgd)
$89,775, and for a 438 1/s (10.0 mgd), 124,965, as seen in Table 19.
Operation and Maintenance Costs
The estimated operation and maintenance costs for the swirl separator
and the aerated grit chamber for capacities of 43.8 1/s (1.0 mgd), 131.4 1/s
(3.0 mgd) and 438 1 /- Hf) Q^mrd> are shown in Table 20. For units with
capacity of 43.8 1/s (u.0 mgd^Xthe annual expenses are estimated at $4^10
for the_a^r^£ad^Jaajab^rUlld'^$4>450 for tn?*swTrT*^e^a7a5or*,r For capacity of
131.4 1/s (3.0 mgd) the annual expensesaJeToTjOUrortne aerated chamber
and $7,430 for the swirl separator. For capacity of 438 1/s /TO.O mgd^
annual expenses are $15.740 for the aerated chamber and $1
swirl separator. "" -
The operator labor is assumed to be 1.5 hours per day for the 131.4 1/s
(1.0 mgd) unit. This assumes 1.0 hours for operation of the equipment and
0.5 hours for disposal of the grit. This is based on the actual experience
at a unit with the capacity where the daily operation ranges from 0.5 to 1.0
hours with occasional periods of 1.5 hours following stoom periods.
49
-------
TABLE 18 CONSTRUCTION COST OF SWIRL CONCENTRATOR AS A GRIT SEPARATOR
Capacity 43.8 1/s (1.0 mgd)
ITEM QUANTITY AMOUNT
Sheet piling 60 sq m $ 6,500
(650 sq ft)
Excavation 95 cu m 1,750
(125 cy)
Reinforced Concrete 10 cu m 3,900
(13 cy)
Equipment Job 16,800
Miscellaneous and Bypass Job 7,400
SUBTOTAL $36,350
Contingent and Engineering Costs 35% 12,650
TOTAL $49,000
Capacity 131.4 1/s (3.0 mgd)
Sheet Piling 70 sq m $ 7,500
(750 sq ft)
Excavation 110 cu m 2,030
(145 cy)
Reinforced Concrete 12 cu m 4,500
(15 cy)
Equipment Job 19,200
Miscellaneous and Bypass Job 8,600
SUB TOTAL $41,830
Contingent and Engineering Costs 35% 15,170
TOTAL $57,000
Capacity 438 1/s (10.0. mgd)
Sheet Piling 100 sq m $10,000
(1000 sq ft)
Excavation 150 cu m 2,730
(195 cy)
Reinforced Concrete 16 cu m 6,300
(21 cy)
Equipment Job 22,000
Miscellaneous and Bypass Job 10,000
SUBTOTAL $51,030
Contingent and Engineering Costs 35% 17,860
TOTAL $68,890
50
-------
TABLE 19 CONSTRUCTION COST OF CONVENTIONAL AERATED GRIT CHAMBER
Capacity 43.8 1/s (1.0 ragd)
ITEM QUANTITY AMOUNT
Sheet Piling 67.5 sq m $ 7,250
(725 sq ft)
Excavation 78 cu m 1,415
(101 cy)
Reinforced Concrete 11 cu m 4,200
(14 cy)
Equipment Job 30,800
Miscellaneous Job 8,100
SUB TOTAL $51,765
Contingent and Engineering Costs 35% 18,120
TOTAL ' $69,885
Capacity 131.4 1/s (3.0 mgd)
Sheet Piling 98 sq m $10,660
(1066 sq ft)
Excavation cu m 2,325
(127 cy)
Reinforced Concrete cu m 7,200
(27 cy)
Equipment Job 36,400
Miscellaneous Job 9,900
SUBTOTAL $66,485
Contingent and Engineering Costs 35% 23,270
TOTAL $89,775
Capacity 438 1/s (10.0 mgd)
Sheet Piling 157 sq m $17,100
(1710 sq ft)
Excavation 276 cu m 5,054
(361 cy)
Reinforced Concrete 34.2 cu m 13,410
(44.7 cy)
Equipment Job 45,000
Miscellaneous Job 12,000
SUBTOTAL $92,565
Contingent and Engineering Costs 35% 32,400
TOTAL $124,965
51
-------
The labor rate used of $7.00 per hour is intended to include the
actual labor cost plus all benefits but excludes administration and general
expenses of the overall plant.
Based on the results shown in Table 20, the annual operation costs of
the aerated grit chamber will exceed the annual costs of the swirl separator
by about 10 percent for each size unit.
Present.Worth
The present worth of the grit removal units is shown in Table 21. The
present worth is based on a life of 20 years and an interest rate of 6-1/8
percent. Hence the present worth of the operation and maintenance costs for
a 20-year period is 11.35 times the annual cost.
For the unit with capacity of 43.8 1/s (1.0 mgd) the present worth of
the aerated-chamber is $125,885 and the swirl separator is $100,000. Thus
the present worth of the aerated chamber is 26 percent greater than that of
the swirl separator.
For the unit with capacity of 131.4 1/s (3.0 mgd) the present worth of
the aerated chamber is 183,755 compared to $141,000 for the swirl separator.
Thus the present worth of the aerated chamber is 30 percent greater than that
of the swirl separator.
For the 438 1/s (10.0 mgd) unit, the present worth of the aerated
chamber is $303,615 compared to $219,280 for the swirl separator, or 38 per-
cent greater.
52
-------
TABLE 20
OPERATION AND MAINTENANCE COSTS FOR GRIT REMOVAL
Capacity 43.8 1/s (1.0 mgd)
Aerated Swirl
Chamber Separator
1. Labor
Operation 1.5 hr/day @ $7.00/hr $3,830 $3,830
Maintenance 0.2 hr/day @ $7.00/hr 510 510
2. Materials, and Supplies 200 100
3. Power
1 Compressor @ 1 hp, 24 hr/day x $0.04/kwh 350
1 Screw Conveyor @ 1/2 hp, 1 hr/day x $0.04/kwh 10 10
1 Bucket Conveyor @ 1/2 hp, 1 hr/day x $0.04/kwh 10_
TOTAL ANNUAL COSTS $4,910 $4,450
Capacity 131.4 1/s (3.0 mgd)
1. Labor
Operation 2.5 hr/day @ $7.00/hr $6,490 $6,490
Maintenance 0.3 hr/day @ $7.00/hr 770 770
2. Materials and Supplies 300 150
3. Power
1 Compressor @ 2 hp, 24 hr/day x $0.04/kwh 700
1 Screw Conveyor @ 1/2 hp, 2 hr/day x $0.04/kwh 20 20
1 Bucket Conveyor @ 1/2 hp, 2 hr/day x $0.04/kwh 20
TOTAL ANNUAL COSTS $8,300 $7,430
Capacity 438 1/s (10.0 mgd)
1. Labor
Operation 4.5 hr/day @ $7.00/hr $11,680 $11,680
Maintenance 0.5 hr/day @ $7.00/hr 1,280 1,280
2. Materials and Supplies 600 250
3. Power
1 Compressor @ 6 hp, 24 hr/day x $0.04/kwh 2', 100-
1 Screw Conveyor @ 1/2 hp, 4 hr/day x $0.04/kwh 40 40
1 Bucket Conveyor @ 1/2 hp, 4 hr/day x $0.04/kwh 40
TOTAL ANNUAL COSTS $15,740 $13,250
53
-------
TABLE 21
PRESENT WORTH
GRIT REMOVAL UNITS
Capacity 43.8 1/s (1.0 mgd)
Aerated Swirl
Chamber Separator
Construction Cost $69,885 $ 49,000
Operation and Maintenance Cost 56,000 . , 51?000
COST TOTAL PRESENT WORTH $125,885 $100,000
Capacity 131.4 1/s (3.0 mgd)
Construction Cost $89,755 $ 57,000
Operation and Maintenance Cost 94.000 84,000
TOTAL PRESENT WORTH $183,755 $141,000
Capacity 438 1/s (10.0 mgd)
Construction Cost $124,965 $ 68,890
Operation and Maintenance Cost 178,650 150,390
TOTAL PRESENT WORTH $303,615 $219,280
54
-------
REFERENCES
1. Sullivan, Richard H. The Swirl Concentrator as a Combined Sewer
Overflow Regulator Facility. EPA-R2-72-008 (NTIS No. PB-214-687),
U.S. Environmental Protection Agency, September, 1972. 179 pp.
2. Sullivan, Richard H., et al. The Swirl Concentrator as a Grit
Separator Device. EPA-670/2-74-026 (NTIS No. PB-234-175/8) U.S.
Environmental Protection Agencyj June, 1974. 93 pp.
3. Chasick, A.H. and Bugher, Theodore B. Using Graded Sand to Test
Grit Removal Apparatus. Journal of the Water Pollution Control Fed-
eration. Vol. 36, No. 7 p. 884, July, 1964.
4. American Society of Civil Engineers and The Water Pollution Control
Federation. Design and Construction of Sanitary and Storm Sewers.
ASCE-Manual and Reports on Engineering Practice - No. 37 (WPCF Man-
ual of Practice No. 9). 1969. p. 33.
55
-------
APPENDIX
TABLE A-l
TEST DATA SWIRL FLOW 43.8 1/s (1.0 mgd)
MAY 23 - 29, 1975
Sample
nhflfi-ir.k # 1
Chasiek * 2
nhaRlr.k # 3
C-rif S.C .Post-Wash
Grit D.O.C. Eff.
Grit- S.C. Pre-Wash
Grit D.O.C. Inf.
A.G.C. * 1 Inf.
Swirl Eff.
P.I.
Grit
(ft: /day)
0.55
0.20
0.076
25.1
52.1
fm
Grit, Dry
(Ibs/day)
9.04
2.13
0.74
.
—
Total
Solids
tt)
.
.
.
35.3
62.7
^
.
«
—
^
»
Vol. Total
Solids
tt)
54.3 *
53.1 *
59.2 *
45.7
16.6
—
.
—
—
^
_
Susp.
Solids
(rna/l)
_
—
—
—
—
2490
728
266
248
249**
184**
Vol. Susp.
Solids
(mK/1)
M
—
—
_
—
1950
395
199
193
184**
143**
Putres-
cibles
(%)
*
»
...
1.4 +
0.8 +
9.1 +
0.9 +
_
-
-
-
BOD
(TSS)
(me/I)
_
_
_
—
—
_
_
158
(223)-*-
.
17O
(260) +
-
COD
(TSS)
(mK/1)
w
.
.
.
..
_
_
389
(223)+
-
yri
(260)+
-
Ui
A.G.C.
D.O.C.
S.C.
Inf.
Eff.
P.I.
Aerated Grit Chamber
Dorr-Oliver Classifier
Swirl Concentrator
Influent
Effluent
Primary Influent
AGC FLOW 46.3 mgd
* Average of 2 samples/week
** Average weekly, flow adjusted
+ Single sample analysis
-------
TABLE A-2
TEST DATA SWIRL FLOW 87.6 1/s (2.0 mgd)
MAY 31 - JUNE 6, 1975
Sample
Chasick # 1
Chasick f 2
Chasick t 3
Grit S.C. Post-Wash
Grit D.O.C. Eff.
Grit S.C. Pre-Wash
Grit D.O.C. Inf.
A.G.C. # 1 Inf.
Swirl Eff.
A.G.C. # 2 Inf.
P.I.
Grit
(ftJ/day)
0.35
0.37
0.41
16.4
52.1
.
.
.
.
.
_
Grit, Dry
(Ibs/day)
8.14
3.55
2.86
—
—
„
.
.
.
M
Total
Solidc
—
.
46.6
64.6
.
.
.
.
_
Vol. Total
Solids
20.8 *
41.9 *
70.4 *
35.1
16.0
.
.
.
_
_
Susp.
Solids
(mg/1)
9t
—
.
—
^
1130
998
233
223
239**
194**
Vol . Susp
Solids
(mg/1)
—
—
..
^
^
780
358
184
173
194**
157**
Putres-
cibles
^
^
.
2.4 +
1.3 +
Not Run+
Not Run+
.
.
—
_
BOD
(TSS) .
(mg/1)
—
^
.
^
^
—
.
176
(288)+
.
172
(245)+
_
COD
TSS)
Bg/D
^
^
.
—
—
^
^
414
(288)+
.
435
(245)+
_
A.G.C.
D.O.C.
S.C.
Inf.
Eff.
P.I.
Aerated Grit Chamber
Dorr-Oliver Classifier
Swirl Concentrator
Influent
Effluent
Primary Influent
**
AGC FLOW 49.7 mgd
Average of 2 samples/week
Average weekly, flow adjusted
Single sample analysis
-------
TABLE A-3
TEST DATA SWIRL FLOW 131.4 1/s (3.0 mgd)
JUNE 12-16 AND 20-21, 1975
Sample
Chasick # 1
Chasick # 2
Chasick t 3
Grit S.C. Post-Wash
Grit D.O.C. Eff .
Grit S.C. Pre-Wash
Grit D.O.C. Inf.
A.G.C. # 1 Inf.
Swirl Eff.
A.G.C. # 2 Inf.
P.I.
Grit
(ffVday)
0.33
0.47
0.45
16.1
67.5
—
—
—
_
_
-
Grit, Dry
(Ibs/day)
9.40
3.17
2.33
—
—
«•
—
—
—
_
-
Total
Solids
01)
—
—
—
57.8
67.2
—
_
—
w
.
-
Vol. Total
Solids
(%)
17.5 *
61.4 *
66.9 *
23.6
17.3
_
—
—
M
_
-
Susp.
Solids
(mg/D
• —
—
_
—
_
364
347
219
195
209**
147**
Vol. Susp.
Solids
UK/I)
M
_
^
_
—
290
271
173
156
160**
112**
Putres-
cibles
00
^
—
^
1.4+
0.2+
0.8+
2.5+
<—
^
—
-
BOD
(TSS)
(mg/l)
.
.
.
.
M
.
.
155
(189)+
_
163
(242)4
_
COD
(TSS)
(mR/1)
.
394
(189)+
383
(242)+
«.
Ui
oo
A.G.C.
D.O.C.
S.C.
Inf.
Eff.
P.I.
Aerated Grit Chamber
Dorr-Oliver Classifier
Swirl Concentrator
Influent
Effluent
Primary Influent
*
**
AGC FLOW 49.0 mgd
Average of 3 samples/week
Average weekly, flow adjusted
Single sample analysis
-------
RUN
Ul
VD
TABLE A-4
TEST DATA SWIRL FLOW 21.9 !/• (0.5 mgd)
AUGUST 27, 1975
CHASICK SAMPLE GRIT
# # cu ft/hr.
1
2
*3
1
2
*3
1
2
*3
1
2
*3
1
2
*3
1
1
1
2
2
2
3
3
3
4
4
4
5
5
5
0.013
0.017
0.058
0.009
0.012
0.048
0.014
0.016
0.074
0.011
0.011
0.042
0.012
0.010
0.084 •
DRY GRIT
Ibs/hr.
0.324
0.117
0.163
0.133
0.057
0.114
0.432
0.074
0.225
0.138
0.042
0.116
0.086
0.029
0.195
% SIEVE ANALYSIS,
vol. sol
29.2
54.5
74.5
52.6
57.3
75.5
17.2
49.4
78.2
32.6
54.7
73.0
60.9
67.9
83.0
100
16.4
71.4
40.2
26.5
81.1
58.8
8.9
72.9
38.7
19.6
72.8
49.7
25.1
72.9
56.6
60
40.4
89.5
. 55.6
47.8
94.2
75.6
34.8
93.4
54.8
52.8
90.1
66.4
48.2
88.2
75.8
% FINER
35
87.3
98.3
70.6
71.7
98.3
87.8
86.1
99.1
70.3
93.1
97.6
80.2
72.3
96.4
89.9
THAN U.S.
18
93.9
99.8
83.2
85.4
99.6
95.4
96.7
100.0
83.2
98.4
98.8
88.6
83.3
96.4
95.0
. SIEVE NUMBER (WGT)
10
98.4
100.0
92.1
94.6
100.0
98.4
99.1
100.0
92.9
99.8
100.0
95.2
94.0
96.4
97.0
6
99.8
100.0
96.3
98.4
100.0
99.2
99.8
100.0
97.4
100.0
100.0
98.2
99.3
97.6
98.0
S
S
S
NOTES: ^Indicates a representative sample, rather than entire Chasick contents was used for
analysis. In no instances were the sample sizes less than \ of the total sample.
S » Flow Spiked with Sand.
-------
TABLE A-5
RUN CHASICK SAMPLE
* *
1
2
*3
*1
2
*3
*1
*2
*3
*1
*2
*3
*1
*2
*3
1
1
1
2
2
2
3
3
3
4
4
4
5
5
5
GRIT
cu ft/hr.
0.013
0.020
0.048
0.042
0.016
0.028
0.060
0.042
0.042
0.075
0.050
0.042
0.058
0.050
0.067
TEST DATA SWIRL FLOW 43.8 1/s (1.0 mgd)
AUGUST 28, 1975
DRY GRIT % SIEVE ANALYSIS. % FINER THAN U.S. SIEVE NUMBER (WGT)
Ibs/hr. vol. sol.
0.242
0.122
0.119
0.783
0.100
0.140
0.453
0.095
0.414
0.531
0.170
0.128
0.844
0.238
0.174
34.8
46.
59,
25,
38,
.5
.4
.9
.3
59.7
44.9
62.4
56.8
31.1
48.2
65.0
27.6
47.2
66.1
100
11.5
51.0
41.9
11.6
53.6
28.1
23.4
57.1
28.2
14.6
61.5
37.9
11.4
43.2
49.2
60.
25.4
77.5
64.6
29.7
82.1
45.4
.37.7
76.0
46.4
32.0
87.3
57.5
30.8
69.9
66.1
35
48.0
91.4
82.8
80.4
92.7
62.7
60.7
89.8
63.7
82.3
95.8
75.7
73.6
86.4
82.3
18.
70.9
96.6
90.9
91.7
96.2
76.7
79.6
94.9
78.5
-92.4
97.9
86/8
87.7
94.4
90.8
10.
89.1
99.1
97.0
97.6
98.4
89.2
92.0
98.5
90.7
97.5
99.0
95.0 -
95.6
98.9
96.2
6.
96.8
99.6
99.5
99.5
99.3
96.2
98.3
100.0
96.3
99.2
99.3
98.6
98.9
99.7
98.5
S
S
S
NOTES:
* See Table
S - Flow Spiked with Sand
-------
TABLE A-6
TEST DATA SWIRL FLOW 87.6 1/s (2.0 mgd)
AUGUST 29, 1975
RUN CHASICK SAMPLE GRIT DRY GRIT
f # cu ft/hr. Ibs/hr.
3
*1
*2
*3
*1
*2
*3
*1
*2
*3
*1
*2
*3
1
*2
*3
1
1
1
2
2
2
3
3
3
4
4
4
5
5
5
0.033
0.037
0.040
0.037
0.048
0.053
0.038
0.055
0.065
0.033
0.037
0.065
0.008
0.050
0.075
0.305
0.226
0.175
0.693
0.361
0.230
0.686
0.392
^0.241
0.579
0.236
0.221
0.109
0.164
0.253
% SIEVE ANALYSIS, % FINER THAN U.S. SIEVE NUMBER (WGT)
vol. sol.
43.8
54.0
64.6
.21.6
37.6
70.9
20.4
43.4
70.8
20.9
37.9
71.9
40.5
68.8
75.5
100
17.4
23.2
39.2
9.7
18.4
44.2
6.9
23.2
42.3
8.1
22.9
32.3
6.4
24.0
48.9
60
32.3
40.5
61.2
32.1
47.5
65.8
18.6
56.6
61.7
23.6
54.4
49.4
16.4
39.1
72.3
35
54.3
59.4
78.1
79.8
77.7
81.8
51.9
92.9
77.1
61.3
87.3
66.5
49.7
57.3
90.0
M.
73.8
75.4
88.3
91.8
88.2
91.7
75.3
97.4
88.5
82.7
94.3
81.2
75.0
71.9
96.4
19.
91.0
89.0
96.5
97.1
95.8
97.2
92.0
99.4
96.5
94.4
98.4
94.1
92.4
85.4
99.3
6.
97.7
96.5
99.6
99.1
98.6
98.9
98.4
99.7
99.4
98.6
99.7
99.4
98.3
94.8
100.0
S
S
S
NOTES:
*See Table
S « Flow Spiked with Sand
-------
TABLE A-7
TEST DATA SWIRL FLOW 131.4 1/s (3.0 mgd)
AUGUST 30, 1975
RUN CHASICK SAMPLE GRIT
4 f cu ft/hr.
N> 3
1
2
*3
1
2
*3
1
2
*3
1
*2
*3
1
*2
*3
1
1
1
2
2
2
3
3
3
4
4
4
5
5
5
0.020
0.023
0.030
0.030
0.023
0.042
0.037
0.025
0.058
0.025
0.042
0.067
0.025
0.033
0.067
DRY GRIT
Ibs/hr.
0.141
0.129
0.117
0.393
0.519
0.202
0.443
0.645
0.271
0.739
0.436
0.279
0.248
0.187
0.221
7.
vol. sol.
55.9
66.8
68.2
32.0
21.4
70.1
29.8
18.7
64.5
25.2
51.2
73.4
44.3
60.9
71.4
SIEVE ANALYSIS. % FINER THAN U.S. SIEVE NUMBER (WGT)
100
7.7
11.8
39.2
16.2
11.2
49.0
16.1
9.0
26.1
8.1
26.4
43.8
13.5
29.3
42.4
60.
16.3
25.7
54.1
40.5
31.3
75.0
38.4
26.1
41.9
24.4
50.3
63.0
23.9
41.6
65.7
35.
41.2
41.2
69.0
83.4
80.6
93.5
83.0
80.8
57.7
77.2
87.5
78.8
45.6
57.1
80.2
18
65.2
59.0
80.4
92.3
90.7
98.0
92.8
92.1
73.9
90.5
94.4
90.4
70.3
73.2
90.7
10_
82.8
75.5
90.7
97.7
97.8
99.0
98.1
97.6
89.7
96.9
98.6
97.2
88.9
88.7
95.9
6.
91.4
88.4
97.4
99.5
99.7
99.5
99.6
99.5
98.2
99.3
99.5
99.3
97.1
97.7
97.1
S
S
S
NOTES:
* See Table
S » Flow Spiked with Sand
-------
ON
OJ
TABLE A-8
AERATED GRIT CHAMBER DATA
SINGLE CHAMBER HIGH FLOW
Influent Effluent
Date
4/28/76
4/29/76
4/30/76
Time
7:30 am
9:30 am
10:30 am
12:30 pm
8:00 am
9:00 am
10:00 am
11:00 am
12:00 am
8:00 am
9:00 am
Total
AGC
Flow-mgd
35
50
70
69
22.3
36.5
62
61
68
23.5
36
Sampler No. 1
Flow gpm
21.8
21.8
21.8
21.8
21.8
21.8
21.8
21.8
21.8
21.8
21.8
Grit Sampler No. 3
Volume
Quarts ' Flow gpm
2.25 21.8
21.8
21.8
2.0 21.8
21.8
21.8
2.0 21.8
21.8
3.75
21.8
2.0 21.8
Grit
Volume
Quarts
2.5
2.25
2.0
3.5
1.75
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-77-185
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
FIELD PROTOTYPE DEMONSTRATION OF THE SWIRL DEGRITTER
5. REPORT DATE
September 1977 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
7.AUTHOR(S)
Richard H. Sullivan, James E. Ure and Paul Zielinski
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
AMERICAN PUBLIC WORKS ASSOCIATION
1313 East 60th Street
Chicago, Illinois 60637
10. PROGRAM ELEMENT NO.
1BC611
11. CONTRACT/GRANT NO.
Grant No. S803157
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory—Gin.,
Office of Research & Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
OH
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/600/14
15.SUPPLEMENTARY NOTES Project Officer: Richard Field (201) 321-6674, FTS 340-6674.
This report supplements EPA-670/2-74-039, "Relationship Between Diameter and Height for the Design of a
Swirl Concentrator as a Combined Sewer Overflow Regulator."
16. ABSTRACT
A prototype swirl degritter was tested by the Metropolitan Denver Sewage Disposal District No. 1. The unit was designed
to duplicate the grit removal device needed to degrit the underflow from the proposed swirl concentrator as a combined
sewer overflow regulator at Lancaster, Pennsylvania under EPA Grant No. S802219 (formerly 11023 GSC). Degritting is
considered in Lancaster to protect pumps and prevent siltation in the interceptor.
The 1.8 m (6 ft) diameter device was designed for a flow of 65.6 1/s (1.3 mgd). It was found that under the physical
arrangements in Denver, testing with domestic sanitary wastewater, the swirl unit performed at slightly less efficiency than
the conventional aerated grit unit which was operating at less than twice the normal flow-through rate. The characteristics of
the grit removal from the swirl degritter were excellent and particles of 0.3 mm (.012 in.) were removed.
Analyses of grit removal was accomplished with three Chasick sampling units. Blasting sand was added to provide
extremely high concentrations of 0.2 mm (.008 in.) particles (lower definition of grit) to duplicate the concentrate from the
swirl regulator. It was found that the unit could efficiently remove the small particles at the high concentrations.
It was concluded that the degritter could be used for domestic wastewater, combined sewer overflows, or urban
stormwater runoff treatment. The absence of moving parts in the basic unit and small relative volume 1:10 (compared to
conventional grit chambers) may make the unit particularly desirable for many applications. A comparison of the present
worth of the cost of construction, operation, and maintenance for a 20 year life indicates that the swirl degritter is from 26
to 3 8 percent less costly than a conventional aerated grit chamber.
This report is submitted in partial fulfillment of EPA Grant S803157 by the American Public Works Association under
the sponsorship of the U.S. Environmental Protection Agency. This report covers a period from January 1975 to August
1976, and work was completed as of December 1976.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
Grit chamber^
Prototypes
Water treatment
Overflows
Combined sewer overflow
Stormwater treatment
Stormwater discharge
Swirl Degritter
13B
18. DISTRIBUTION STATEMENT
19. SECURITY CLASS (ThisReport)'
Unclassified
21. NO. OF PAGES
74
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
64
•frU S. GOVERNMENT PRINTING OFFICE 1977— 757-056 /6555
------- |