EPA/600/2-88/022
March 1988
AERATION EQUIPMENT EVALUATION:
PHASE I - CLEAN WATER TEST RESULTS
by
Fred U. Yunt
Tim 0, Hancuff
County Sanitation Districts of Los Angeles County
Los Angeles, California 90607
Contract No. 14-12-150
Project Officer
Richard C. Brenner
Wastewater Research Division
Water Engineering Research Laboratory
Cincinnati, Ohio 45268
WATER ENGINEERING RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
Development of the information in this report has been funded in part
by the U.S. Environmental Protection Agency under Contract No. 14-12-150
to the County Sanitation Districts of Los Angeles County. The report has
been subjected to Agency peer and administrative review and approved for
publication as an EPA document. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use.
ii
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FOREWORD
The 'J.S. "{•wironmental Protection Agency (EPA) is charged by
Congress with protecting the Nation's land, air, and water systems.
Under a mandate of national environmental laws, the agency strives to
formulate and implement actions leading to a compatible balance between
human activities and the ability of natural systems to support and
nurture life. The Clean Water Act, the Safe Drinking Water Act, and
the Toxics Substances Control Act are three of the major congressional
laws that provide the framework for restoring and maintaining the
integrity of our Nation's water, for preserving and enhancing the
water we drink, and for protecting the environment from toxic
substances. These laws direct EPA to perform research to define our
environmental problems, measure the impacts, and search for solutions.
The Water Engineering Research Laboratory is that component of
EPA's Research and Development program concerned with preventing,
treating, and managing municipal and industrial wastewater discharges;
establishing practices to control and remove contaminants from
drinking water and to prevent its deterioration during storage and
distribution; and assessing the nature and controllability of releases
of toxic substances to the air, water, and land from manufacturing
processes and subsequent product uses. This publication is one of the
products of that research and provides a vital communication link
between the researcher and the user community.
As part of these activities, an aeration equipment evaluation was
undertaken at the Joint Water Pollution Control Plant of Los Angeles
County Sanitation Districts using the non-steady state clean water
test procedure. Systems chosen for evaluation represented various
submerged generic aeration devices. Seven manufacturers participated
in the study. Information documented herein should be of particular
interest to design engineers and municipal officials charged with
selecting aeration equipment for new activated sludge treatment plants
and/or considering a retrofit to new equipment in existing plants.
Francis T. Mayo, Director
Water Engineering Research Laboratory
m
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ABSTRACT
This research project was initiated with the principle objective of
evaluating the oxygen transfer performance of various generic aeration
systems used in activated sludge wastewater treatment. A secondary
objective of the project was to evaluate various oxygen transfer data
analysis methods in current use.
Working in conjunction with an EPA-retained consultant and the
equipment manufacturers, clean water tests were conducted on eight types of
submerged aerators. All aerator testing was conducted in the same tank and
used the same procedures in order to provide standard test conditions.
Results of this work indicated that, of the systems tested, fine
bubble diffusion equipment transferred oxygen most efficiently in clean
water. Results also indicated that, in clean water, jet aeration equipment
transfers oxygen more efficiently than do coarse bubble aeration systems.
However, because the value of wastewater correction factors (alpha and
beta) are dependent on the type of aerator tested, the relative
performance of the aerators to one another in wastewater may be
different.
This report was submitted in fulfillment of Contract No. 14-12-150 by
the County Sanitation Districts of Los Angeles County under partial
sponsorship of the U.S. Environmental Protection Agency. This report
covers the test period February 15, 1978, through March 16, 1979.
iv
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CONTENTS
Foreword i i i
Abstract iv
Figures viii
Tables xi
Nomenclature xiii
Conversion Factors , xxi
Acknowledgements xxii
1. Introduction 1
Background and Overview , 1
Project Outl ine 2
2. Conclusions and Recommendations 4
3. Equipment and Testing Procedures 6
Test Facility 6
Test Procedures 6
Airflow measurements 6
Dissolved oxygen sample collection 11
Dissolved oxygen measurements 16
Aerator power determinations 16
Power density calculations 23
Headloss measurements , 24
Deoxygenation procedure 25
Field Experiment Procedure 25
v
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CONTENTS (continued)
4. Oxygen Transfer Data Analysis 29
Field Measurements 29
Basic Theory 29
Determination of K(_at and C* 35
Least Squares Regression Methods 37
Need for Data Truncation 38
Parameters at Standard Conditions 39
K[_a2o determination 39
C*0 determination 40
Evaluation of Data Acceptability *. 42
Primary Data Analysis Method 42
Standard Oxygen Transfer Calculations 43
Determination of Standard Aeration Efficiency 44
5. Aeration System Descriptions 45
Overview 45
Fine Bubble Dome Diffusers 45
Fine Bubble Tube Diffusers 48
Jet Aerators 48
Static Tube Aerators 53
Variable Orifice Coarse Bubble Diffusers 53
Fixed Orifice Coarse Bubble Diffusers - D-24 60
Fixed Orifice Coarse Bubble Diffusers - Superfuser 65
Fixed Orifice Coarse bubble Diffusers - Deflectofuser 70
6. Test Results 73
Overview. 73
Tabular Presentations 74
Presentation of analysis results for the Exponential
and Equilibrium Methods 74
Comparison of analysis results for the Exponential
and Equilibrium Methods 74
Graphical Presentations 91
Water depth relationships 92
Delivered power density relationships 95
7. Problems Associated with Clean Water Testing... 112
Overview 112
Degassing of High Level Dissolved Oxygen Samples 112
B1 ower Pulsation 113
Excessive K|_a Variation 115
Jet Aerator Pump Power Measurement 116
Tap Water Foaming 117
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CONTENTS (continued)
8. Follow-On Research Activities. 123
References 124
Appendices
A. Airflow Meter Equations.... 125
B. Preamble to Appendices C through J 128
C. Individual Performance Results for Norton
Fine Bubble Dome 01 ffusers , 129
D. Individual Performance Results for FMC
Fine Bubble Tube Diffusers 136
E. Individual Performance Results for Pentech
Jet Aerators 143
F. Individual Performance Results for Kenics
Static Tube Aerators.... 150
G. Individual Performance Results for Bauer
Variable Orifice Diffusers..... 157
H. Individual Performance Results for Sanitaire
Coarse Bubble Diffusers 164
I. Individual Performance Results for Envirex
Coarse Bubble Diffusers. 171
J. Individual Performance Results for FMC
Coarse Bubble Oiffusers 178
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FIGURES
Number Page
1 Clean Water Testing Facility . 7
2 Orifice Plate for 3-in. Air Line 12
3 Orifice plate for 4-in. Air Line 13
4 Annubar Flow Measurement Device 14
5 Horsepower Schematics 21
6 Primary Curve Plots for Equilibrium and Exponential
Data Analysis Methods 36
7 Test Tank Configuration for the Norton Dome
Diffuser Aeration System 46
8 Norton Dome Diffuser 47
9 Test Tank Configuration for the FMC Pearl comb
Tube Diffuser Aeration System 49
10 FMC Pearlcomb Diffuser 50
11 Test Tank Configuration for the Pentech EMJA
Unit at the 10-ft Water Depth 51
12 Pentech Directional Mix Jet Aerator (DMJA) 52
13 Test Tank Configuration for the Pentech DMJA
Unit at the 15-ft Water Depth 54
14 Pentech Eddy Mix Jet Aerator (EMJA) 55
15 Test Tank Configuration for the Pentech EMJA
Unit at the 20- and 25-ft Water Depths 56
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FIGURES (continued)
16 Test Tank Configuration for the Kenics Static Tube
Aeration System at the 10- and 15-ft Water Depths 57
17 Kenics Static Tube Aerator ...— . 58
18 Test Tank Configuration for the Kenics Static
Tube Aeration System at the 20- and 25-ft Water Depths 59
19 Bauer Airpac Diffuser 61
20 Test Tank Configuration for the Bauer Model II Airpac
Aeration System at the 10- and 20-ft Water Depths 62
21 Test Tank Configuration for the Bauer Model III Airpac
Aeration System at the 15- and 25-ft Water Depths., 63
22 Sanitaire D-24 Diffuser 64
23 Test Tank Configuration for the Sanitaire D-24 Aeration
System at the 10- and 20-ft Water Depths 66
24 Test Tank Configuration for the Sanitaire D-24 Aeration
System at the 15- and 25-ft Water Depths 67
25 Envirex Superfuser Diffuser.. 68
26 Test Tank Configuration for the Envirex Superfuser
Aeration System 69
27 FMC Deflectofuser Diffuser 71
28 Test Tank Configuration for the FMC DefTectofuser 72
(Sparger) Aeration System at the 15-ft Water Depth
29 Comparative Plot of SOTR vs. Water Depth at
Middle Power Density Tested 93
30 Comparative Plot of SOTE vs. Water Depth at
Middle Power Density Tested 94
31 Comparative Plot of SWAE vs. Water Depth at
Middle Power Density Tested 96
32 Comparative Plot of SOTR vs. Delivered Power Density at
10-ft Water Depth 97
IX
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FIGURES (continued)
33 Comparative Plot of SOTE vs. Delivered Power Density at
10-ft Water Depth 98
34 Comparative Plot of SWAE vs. Delivered Power Density at
10-f t Water Depth 100
35 Comparative Plot of SOTR vs. Delivered Power Density at
15-ft Water Depth 101
36 Comparative Plot of SOTE vs. Delivered Power Density at
15-ft Water Depth 102
37 Comparative Plot of SWAE vs. Delivered Power Density at
15-ft Water Depth 103
38 Comparative Plot of SOTR vs. Delivered Power Density at
20-ft Water Depth 105
39 Comparative Plot of SOTE vs. Delivered Power Density at
20-ft Water Depth 106
40 Comparative Plot of SWAE vs. Delivered Power Density at
20-ft Water Depth 107
41 Comparative Plot of SOTR vs. Delivered Power Density at
25-ft Water Depth 108
42 Comparative Plot of SOTE vs. Delivered Power Density at
25-ft Water Depth 109
43 Comparative Plot of SWAE vs. Delivered Power Density at
25-ft Water Depth Ill
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TABLES
Number Page
1 Summary of Water Quality Characteristics 8
2 Field Measurements.. 30
3 Summary of Exponential Method Results: Norton
Fine Bubble Dome Diffusers..... 75
4 Summary of Equilibrium Method Results: Norton
Fine Bubble Dome Diffusers 76
5 Summary of Exponential Method Results: FMC
Fine Bubble Dome Diffusers 77
6 Summary of Equilibrium Method Results: FMC
Fine Bubble Dome Diffusers 78
7 Summary of Exponential Method Result: Pentech
Jet Aerators 79
8 Summary of Equilibrium Method Results: Pentech
Jet Aerators 80
9 Summary of Exponential Method Results: Kenics
Static Tube Aerators 81
10 Summary of Equilibrium Method Results: Kenics
Static Tube Aerators 82
11 Summary of Exponential Method Results: Bauer
Course Bubble Diffusers 83
12 Summary of Equilibrium Method Results: Bauer
Variable Orifice Diffusers.. 84
13 Summary of Exponential Method Results: Sanitaire
Course Bubble Diffusers.... 85
xi
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TABLES (continued)
14 Summary of Equilibrium Method Results: Sanitaire
Course Bubble Diff users 86
15 Summary of Exponential Method Results: Envirex
Course Bubble Diff users 87
16 Summary of Equilibrium Method Results: Envirex
Course Bubble Diff users 88
17 Summary of Exponential Method Results: FMC
Course Bubble Diff users 89
18 Summary of Equilibrium Method Results: FMC
Course Bubble Diff users 90
19 Comparison of Analysis Methods 91
20 Foaming Problem Comparison Tests 121
xn
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NOMENCLATURE
List of Basic SymboIs
Symbol Description
C
C*
D
e
h
K[_a
dissolved oxygen (D.O.) concentration
D.O. saturation value
D.O. deficit (driving force)
efficiency
airflow correction factor
differential pressure
overall volumetric mass trans-
fer coefficient
aeration efficiency
List of Specific Symbols
Symbol Description
Symbol
Description
p
PD
P
Q
T
t
V
aerator
power
power
density
pressure
measured
airflow at
standard
conditions
temperature
time
volume of
liquid in
aeration
tank
water depth
Units
calculated D.O. concentration at time t
mg/L
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NOMENCLATURE (continued)
List of Specific Symbols (continued)
Symbol Description Urnjs
Cf final D.O. concentration corresponding to mg/L
time tf
C-j initial D.O. concentration corresponding to mg/L
time tj
Cm measured D.O. concentration at time t mg/L
Ct D.O. concentration at time t mg/L
C* D.O. saturation value mg/L
C*hT handbook D.O. saturation value at temperature T, mg/L
14.70 psia, dry air, and 20.9% QZ by volume
C*h20 handbook D.O. saturation value at 2Q°C, 14.70 mg/L
psia, dry air and 20.9% 02 by volume (9.17 mg/L)
C*md measured or derived D.O. saturation value at mg/L
temperature T and barometric pressure pa
C*0 projected field D.O. saturation value at standard mg/L
conditions of 20°C, 14.70 psia, and 0 mg/L D.O.
£*„ projected field D.O. saturation value at time t = » , mg/L
(To, Pao) 20°C, and 14.70 psia, based on the concept of
equivalent depth
Of final D.O. deficit corresponding to time tf mg/L
DT initial D.O. deficit corresponding to time t-j mg/L
D0 D.O. deficit at standard conditions of mg/L
20°C, 14.70 psia, and 0 mg/L D.O.
d actual internal pipe diameter in.
dC/dt oxygen transfer rate per unit volume mg/L
dC/dt0 oxygen transfer rate per unit volume at standard mg/L
conditions of 20°C, 14.70 psia, and 0 mg/L D.O.
eb blower efficiency decimal
xiv
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NOMENCLATURE (continued)
List of Specific Symbols (continued)
Symbol
pe
WV
Nbo
Descr i p_tj_pji
drive or coupling efficiency
motor efficiency
pump efficiency
orifice area correction factor
manometer fluid temperature correction factor
pipe expansion correction factor
relative humidity correction factor
Annubar differential pressure
measured diffuser headloss
estimated aeration system piping headloss
estimated suction piping headloss
orifice plate differential pressure
flow meter constant
overall volumetric mass transfer coefficient
overall volumetric mass transfer coefficient at
temperature T
overall volumetric mass transfer coefficient at 20°C
brake aeration efficiency in clean water at standard
conditions of 20°C, 14.70 psia, and 0 mg/L D.O.
delivered aeration efficiency in clean water at
standard conditions of 20°C, 14.70 psia, and
0 mg/L D.O.
wire aeration efficiency in clean water at
standard conditions of 20°C, 14,70 psia, and
0 mg/L D.O.
xv
Units
decimal %
decimal %
decimal %
n.
in.
psg
psig
in.
1/hr
1/hr
1/hr
Ib of
oxygen
per hp-hr
Ib of
oxygen
per hp-hr
Ib of
oxygen
per hp-hr
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NOMENCLATURE (continued)
List of Specific Symbols (continued)
Symbol
NO
OSR
OTE
OTR
Pa
Pab
Pabs
Pad
Pads
Pans
Paw
paws
Pb
Pbs
Pd
Descriptigji
aeration efficiency in clean water at standard
conditions of 20°C, 14.70 psia, and 0 mg/L D,0.
oxygen supply rate
oxygen transfer efficiency at 0 mg/L D.O,
(maximum deficit)
oxygen transfer rate at 0 mg/L D.O.
(maximum deficit)
air power
air brake power
air brake power at standard conditions of 2Q°C,
14,70 psia, and 36% relative humidity
air delivered power
air delivered power at standard conditions of 20°C,
14.70 psia, and 36% relative humidity
air nominal power at standard conditions of 20°C,
14.70 psia, 36% relative humidity, and a blower inlet
pressure of 14.60 psia
air wire power
air wire power at standard conditions of 20°C,
14.70 psia, and 36% relative humidity
total brake power
total brake power at standard conditions of 20°C,
14.70 psia, and 36% relative humidity
total delivered power
Units
Ib of
oxygen
per hp-hr
Ib of
oxygen
per nr
Ib of
oxygen
per nr
hp
np
hp
hp
hp
hp
hp
hp
hp
hp
xvi
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NOMENCLATURE (continued)
ns
Ppb
Ppd
PpW
Pw
List of Specific: SymboIs (continued)
Symbol Description
total delivered power at standard conditions of 20°C,
14.70 psia, and 36% relative humidity
total nominal power at standard conditions of 20°C,
14.70 psia, 36% relative humidity, and a blower
inlet pressure of 14.60 psia
pump brake power
pump delivered power
pump wire power
total wire power
delivered power density at standard conditions
PDns nominal power density at standard conditions
pa barometric pressure
Pao barometric pressure at standard conditions (14.70 psia)
pc aerator air pressure
Pf flow meter flowing gas pressure
Pfa Annubar flowing gas pressure
Pf0 orifice plate flowing gas pressure
Pi assumed blower inlet pressure (14.6 psia)
Psh aerator static head
Units
hp
hp
hp
hp
hp
hp
hp per
1000
hp per
1000
mm of
mercury
in. of
mercury
in. of
mercury
in. of
mercury
in. of
mercury
in. of
mercury
psia
in. of
mercury
xvn
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NOMENCLATURE (continued)
List of SpecificSymbols (continued)
Symbol Description
Pt Annubar stagnation pressure
PvpT vapor pressure of water at temperature T
Pvp20 vapor pressure of water at 20°C (0.34 psig)
pwa partial pressure of water vapor in ambient air
pwl partial pressure of water vapor in the air line
PI calculated blower inlet pressure
P2 calculated blower discharge pressure
Qa measured airflow at standard conditions using
Annubar
Qmax maximum test airflow for a system at each water depth
Q0 measured airflow at standard conditions using orifice
plate
Qp liquid flow rate produced by jet aerator pump
Qtest averaged airflow value associated with a test
Re Reynolds number of airflow in pipe
RH relative humidity
S0 orifice factor
SOTE oxygen transfer efficiency in clean water at standard
conditions of 20°C, 14.70 psia, and 0 mg/L D.O.
SOTR oxygen transfer rate in clean water at standard
conditions of 20°C, 14.70 psia, and 0 mg/L D.O.
SWD side water depth
Ta ambient air temperature
Units
in. of
mercury
psig
psig
psig
psig
psia
psia
scfm
scfm
scfm
cfs
scfm
Ib of
oxygen
per hr
ft
°F
xvm
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NOMENCLATURE (continued)
List of Specif1c_5ymbo1s (continued)
Symbol Description Units
Tam manometer board air temperature °F
TJJ diffuser air temperature °F
Tf flow meter air temperture °F
TI temperature at blower inlet °F
T0 water temperature at standard conditions (20°C) °C
Tw water temperature °C
TDH total dynamic head of jet aerator pump ft of HgQ
ti time, corresponding to D.O. measurement Cj sec
tf time corresponding to D.O. measurement Cf sec
Vi inflated water volume (aerated)
Vw deflated water volume (not aerated)
Ye orifice plate gas expansion factor
zd diffuser submergence ft
zemd equivalent depth corresponding to the measured or ft
derived D.O. saturation value
Zi inflated water depth (same as side water depth) ft
zw deflated water depth ft
=! (alpha) ratio of Kj_a in wastewater to K[_a in clean
water under identical conditions
8 (beta) ratio of the oxygen saturation in wastewater to
oxygen saturation in clean water under identical
conditions
^air (gamma) specific weight of air at the temperature, Ib per
pressure, and relative humidity for which Q is reported ft3
xix
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NOMENCLATURE (continued)
List of Specific Symbols (continued)
Symbol Description Units
Ywater (ganuna) specific weight of water at 20°C (62.4 Ib/ft3) ib per
ft3
9 (theta) K|_a temperature adjustment factor
u (mu) gas absolute viscosity cps
XX
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CONVERSION FACTORS
Measurement
Aeration Efficiency
Airflow
Barometric Pressure
Density
Depth
Headless
Headloss
Oxygen Supply Rate
Oxygen Transfer Rate
Power
Power Density
Temperature
Water Volume
To Convert From
U.S. Customary Unit
Ib 02/hp-hr
cfm
psia
Ib/ft3
ft
in. of H20
psi
Ib 02/hr
Ib 02/hr
hp
hp/1000 ft3
°F
ft3
To
SI Unit
kg 02/kWh
L/sec
kPa
kg/m3
m
mm H20
kPa
kg 02/hr
kg 02/hr
kW
W/m3
°C
m3
Divide By
1.644
2.119
0.1451
0.06243
3.281
0.03937
0.1451
2.205
2.205
1.341
0.03797
*
35.31
* °C = 5 (°F-32)/9
XXT
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ACKNOWLEDGEMENTS
The untiring effort, cooperation, and numerous contributions of
Gerry Shell of Gerry Shell Environmental Engineers, LaVergne,
Tennessee, are gratefully acknowledged. The generous assistance
rendered by all equipment manufacturers participating in the aeration
equipment evaluation is greatly appreciated. The contributions of the
consultants working for the equipment manufacturers and Michael K.
Stenstrom of the University of California, Los Angeles, are also
gratefully acknowledged.
xxii
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SECTION 1
INTRODUCTION
BACKGROUND AND OVERVIEW
This project was originally conceived by the U.S. Environmental
Protection Agency (EPA) and County Sanitation Districts of Los Angeles
County (LACSD) in the spring of 1977. An arrangement was made to nave the
Districts conduct clean oxygen transfer tests on seven different types of
submerged aeration devices; the deflectofuser (sparger) was later added
because it was widely used both nationwide and in the Districts' treatment
plants. EPA partially funded the project and retained Gerry Shell of Gerry
Shell Environmental Engineers as a consulting engineer. The project was
referred to as the "Aeration Equipment Evaluation - Phase I". A second
phase of the project was considered essential at a later date to compare
oxygen transfer performance in clean water to that in mixed liquor.
The "Aeration Equipment Evaluation - Phase I" project was conducted in
order to accomplish three major objectives. The main purpose was to
evaluate the clean water oxygen transfer performance of various generic
types of aeration equipment under identical testing conditions and using
identical testing methods. A second purpose of the study was to
demonstrate the effects of changing depths and operating power levels on
various types of aeration equipment. Finally, a subobjectiye of the
project was to evaluate various oxygen transfer data analysis methods in
current use.
Analysis of clean water test results for various'generic aeration
devices is the first step toward defining the performance expected from
such equipment. Clean water tests indicate general trends in an aerator's
performance, but they do not necessarily reflect an aerator's performance
under actual conditions. The logical second step, therefore, was the
evaluation of selected submerged aeration equipment under mixed liquor
conditions. Subsequent to the clean water testing studies, LACSD evaluated
three generic types of aeration equipment under mixed liquor conditions at
their Whittier Narrows Water Reclamation Plant in El Monte, California.
This phase of the project is referred to as the "Aeration Equipment
Evaluation - Phase II". The three systems tested were selected on the
basis of their performance during the clean water project. It is hoped
that information obtained from both phases of the "Aeration Equipment
Evaluation" can be used to determine wastewater correction factors (alpha
and beta) that may have applicability to other aeration system designs.
Field test work for the mixed liquor phase of the project was completed in
1982, and a report of these activities is in preparation.
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PROJECT OUTLINE
This study was to be an evaluation of distinct generic types of
equipment; it was not intended to be an evaluation of various
manufacturers' equipment of the same generic type. Due to the large
variety of fixed orifice coarse bubble diffusers on the market, more than
one of this generic type was tested. The following is a complete list of
the equipment tested:
System Description
A Fine bubble ceramic dome diffusers applied
in a total floor coverage configuration
B Fine bubble plastic tube diffusers applied
in a dual aeration configuration
C Jet aerators
D Static tube aerators
E Variable orifice coarse bubble diffusers
F Fixed orifice coarse bubble diffusers
G Fixed orifice coarse bubble diffusers
H Fixed orifice coarse bubble diffusers
[sparger tests conducted at a 4.6-m
(15-ft) depth only]
Manufacturer
Norton Company
FMC Corporation
Pentech-Houdaille
Industries, Inc.
Kenics Corporation
C-E Bauer of
Combustion
Engineering, Inc.
Sanltaire - Water
Pollution Control
Corporation
Envirex, Inc.
FMC Corporation
The tests were conducted at the Districts' Joint Water Pollution
Control Plant in Carson, California. The study was structured to provide
clean water test information at water depths of 3.0 m (10 ft), 4.6 m (15
ft), 6.1 m (20 ft), and 7.6 m (25 ft). A range of nominal power densities
was evaluated at each depth. The manufacturers were given the choice to
test at one of two power options, as follows:
Option 1:
Option 2: 7.9, 13.2, and 26.3 nominal
(0.3, 0.5, and 1.0 nominal hp/1000 ft3)
13.2, 26.3, and 39.5 nominal
(0.5, 1.0, and 1.5 nominal hp/1000 ft3)
It was hoped that each manufacturer would select the range that was
most typical of the equipment's application in mixed liquor. All
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manufacturers tested chose Option 1, with the exception of the Norton
Company, which selected Option 2. The 3 to 1 range in power for both
options was intended to demonstrate the aeration equipment's ability to
handle diurnal variations in process loading.
The manufacturers were responsible for designing the layout of their
equipment subject to the constraints of this study. Each manufacturer was
allowed, if desired, to change its equipment configuration at each depth
tested. It was required, however, that the same configuration be used for
all tests at a given depth.
Testing procedures and testing equipment were decided on by the LACSD
Project Engineers and approved by the EPA consultant. Manufacturers and
other experts in the field reviewed and commented on the test procedures.
All tests were conducted by the LACSD Project Engineers, with each system's
initial tests being witnessed by both the EPA consultant and a
representative of the equipment manufacturer.
Actual testing on the first aeration system (fine bubble dome
diffusers) began in November 1977. Due to technical problems related to
airflow and dissolved oxygen (D.O.) measurements, the official tests of
this system were not completed until May, 1978. The tests on the last
aeration system (coarse bubble sparger) were completed in March, 1979.
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SECTION 2
CONCLUSIONS AND RECOMMENDATIONS
The clean water study provided considerable insight into the performance
characteristics of various submerged aeration devices. The following
conclusions were reached:
(1) For a given water depth and delivered power density, the Standard Wire
Aeration Efficiency (SWAE) of the fine bubble dome diffusers in a total
floor coverage mode was substantially better than that of any other
system tested.
(2) For a given water depth and delivered power density, the SWAE of the
fine bubble tube diffusers in a dual aeration mode was substantially
better than that of either the jet aerators or the various coarse
bubble diffusers.
(3) For a given water depth and delivered power density, the SWAE of the
jet aerators was usually better than that of the various coarse
bubble diffusers (with the exception of the Sanitaire fixed orifice
coarse bubble diffusers in a total floor coverage mode).
(4) For a given water depth, delivered power density, and with similar
configurations* the SWAE's of the various coarse bubble diffusers
were similar.
(5) For a given configuration and water depth, and for an increase in
delivered power density, the SWAE decreased significantly for the
fine bubble tube diffusers, showed a local maximum for the jet
aerators, and showed very little change for the coarse bubble
diffusers.
(6) For a given configuration and delivered power density, and for an
increase in water depth, the SWAE was relatively unaffected for the
fine bubble diffusers and usually increased significantly for the
other types with the exception of the static tube aerators at the
upper water depths.
(7) For a given water depth and delivered power density, the Standard
Oxygen Transfer Efficiency (SOTE) of the fine bubble dome diffusers
in a total floor coverage mode was substantially better than that of
any other system tested.
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(8) For a given water depth and delivered power density, the SOTE's of
the fine bubble tube diffusers in a dual aeration mode and the jet
aerators were similar and significantly better than that of the
various coarse bubble diffusers.
(9) For a given water depth and delivered power density, the SOTE's of
the various coarse bubble diffusers were very similar when installed
in similar configurations.
(10) For a given configuration and water depth, and for an increase in
delivered power density, the SQTE decreased significantly for the
fine bubble diffusers and jet aerators, and usually increased
slightly for the various coarse bubble diffusers (with the exception
of the static tube aerators, where the SOTE was not significantly
affected by changes in delivered power density).
(11) For a given configuration and delivered power density, the SOTE
increased substantially with an increase in water depth for all
systems tested.
(12) The use of a total floor coverage configuration with the Sanitaire
fixed orifice coarse bubble diffusers appeared to improve the
performance of this system significantly.
(13) With the exception of the Sanitaire system, the changes in
configuration experienced during this study did not appear to result
In significant changes in performance.
(14) The exponential and equilibrium methods of clean water data analysis
provided nearly identical results under the conditions of this study.
Based on 100 test analyses, the average ratio of the SWAE obtained by
the exponential method to the SWAE obtained by the equilibrium method
was 0.995, with a standard deviation in the ratio of 0.0169.
Clean water testing can only show the performance trends of an
aeration device and cannot be used alone to determine performance under
process water conditions. For this reason, it is recommended that further
testing be conducted in process water to establish characteristic alpha
factors for the devices evaluated during this study.
-------
SECTION 3
EQUIPMENT AND TESTING PROCEDURES
TEST FACILITY
The test facility used for all tests was an all steel rectangular
aeration tank (Figure 1) located at the LACSD Joint Water Pollution Control
Plant, The dimensions of this tank are 6.1 m X 6.1 m X 7.6 m (20 ft X 20 ft
X 25 ft) side water depth (SWD). Prior to the start of this project, the
tank was steam cleaned and all exposed metal surfaces were coated with coal
tar epoxy. Potable water was used in all clean water tests conducted in
this study. The majority of this water was supplied by the Las Angeles
Metropolitan Water District and was a blend of roughly 45% northern
California water and 55% Colorado River water. Additional amounts of local
well water also contributed to the delivered water supply. Average
characteristics of the supplied water were: total dissolved solids (IDS)
level of 500 mg/L, pH of 8.25, hardness of 225 mg/L as CaC03, and turbidity
of less than 0.1 turbidity units,!/ Additional laboratory measurements
(those made during the testing) are presented in Table 1. The temperature
range of water used in the study was 16.2 to 25.2°C (61.2 to 77.4°F).
The air delivery system used for this project consisted of a Roots Model
RAS-60 rotary positive blower driven by a 56-kW (75-hp) electric motor.
System air was filtered by an Air Maze DA dry type filter. A l-m3 (35-ft^)
pulsation dampening tank was also included in the system between the blower
and the airflow measurement elements. System air rate was adjusted by
bleeding off excess air at the blower.
TEST PROCEDURES
The tests were of the non-steady state nature using sodium sulfite to
deoxygenate the clean water and cobalt chloride as a catalyst. Samples were
withdrawn from the tank and collected in BOD bottles and chemically fixed
for later D.O. measurement by the lodometric (Winkler) method. In addition,
a sample stream was pumped from the tank for continuous D.O. monitoring with
an in-line probe. The official results of this study, however, were based
solely on D.O. measurements using the Winkler technique.,?/ Details of each
aspect of the test procedure follow.
Airf 1 ow jteasurements
Airflow measurements were made with two different primary flow
elements: an orifice plate and an Annubar (a velocity head measuring device
-------
SAMPLING
STACK NS
-10'-
SAMPLING
STACK N2 2
20'
PLAN
MID- .
DEPTH'
1,
2'
V
•=
4
» <
•
1
2'
T
. MID-
'DEPTH
i
2
M
S
1
t
5'
AX.
WD
ELEVATION
Figure 1. Clean water testing facility,
7
-------
TABLE 1. SUMMARY OF WATER QUALITY CHARACTERISTICS
SanpLe
Date
12/15/78
13/23/78
13/24/78
14/11/78
14/12/78
35/06/78
35/08/78
35/18/78
15/25/78
16/02/78
)6/08/78
16/14/78
16/15/78
16/26/78
16/28/78
16/29/78
17/01/78
17/08/78
17/10/78
17/17/78
17/17/78
17/29/78
17/31/78
18/02/78
18/03/78
18/16/78
18/21/78
18/23/78
Manufacturer
Norton
Norton
Norton
Norton
Norton
Norton
Norton
Norton
Kenics
Kenics
Kenics
Kenics
Kenics
Kenics
Kenics
Kenics
Pentech
Pentech
Pentech
Pentech
Pentech
Pentech
Pentech
Pentech
Pentech
Pentech
FMC
FHC
Water
Batch
Nuifcer
1
1
2
2
3
3
4
4
1
1
2
2
3
3
4
4
1
1
p
o
3
3
4
4
5
5
1
!___
Pre-
test
Sanple
/
/
/
/
/
/
/
/
/
/
/
/
j
/
Post-
test
Sample
/
/
/
/
/
/
/
/
/
/
/
/
/
/
Assumed
ft
Na-SO
Cohc.J
(TO/L)
0
142
0
162
0
944
0
565
0
956
0
1127
0
749
0
302
0
1031
0
441
0
734
0
299
0
517
0
1132
Laboratory Results
Alkalinity
(tiK/L CaCOo)
124
149
248
132
139
111
87
98
132
137
95
115
91
94
96
92
86
81
125
93
91
pH
8.00
8.10
8.05
8.35
7.98
8.31
7.11
8.19
8.10
8.50
7.50
8.38
6.10
8.31
8.39
6.20
7.90
8.03
7.87
3.02
7.91
Total
Hardness
(iiK/L CaCO,)
252
255
226
219
181
179
164
161
189
182
181
187
208
214
214
210
216
193
198
?11
?ia
Total
SO,
(n^/ISO^
—
...
810
69
557
109
778
109
1090
141
683
620
182
967
172
746
305
176
152
965
T.D.S.
(TO/L)
624
778
620
1536
414
1025
303
1417
428
1872
446
1317
1173
528
1692
498
1372
831
592
476
1721
Co
(ntf/L)
0.01
0.10
0.05
0.10
<0.01
0.11
0.11
0.10
0.01
0.12
0.01
0.10
0.10
0.03
0.09
<0.01
0.09
0.10
0.11
0.02
0.11
Fe
(ms/L)
—
__-
0.05
0.05
0.09
0.07
0.08
0.02
0.14
0.07
0.15
0.09
0.16
0.21
0.09
0.14
0.14
0.08
O.Ofi
n.os
Ml
KA)
—
—
0.01
0.01
0.01
0.01
0.02
0.01
0.02
0.01
0.03
<0.01
<0.01
0.01
<0.01
0.01
0.01
-------
Sanple
Dace
08/29/78
08/31/78
09/02/70
39/29/78
10/13/78
10/14/78
10/19/7£
10/20/78
10/23/78
10/26/78
10/30/78
10/31/78
)2/08/79
02/10/79
11/06/78
11/07/78
11/08/78
11/15/78
12/05/7E
12/06/78
12/07/78
12/09/78
12/15/78
12/16/78
11/08/79
11/09/79
11/10/79
11/20/79
Manufacturer
FMC
FMC
FMC
FMC
FMC
FMC
FMC
FMC
FMC
FMC
FMC
FMC
FMC
FMC
Sanitaire
Sanltalre
Sanitaire
Sanltalre
Bauer
Bauer
Bauer
Bauer
Bauer
Bauer
Envirex
Envlrex
Envirex
Envirex
TABLE
Water
Batch
Nunber
2
2
3
3
4
4
6
5
6
6
7
7
8
8
1
1
2
2
1
1
2
2
3
3
1
1
2
2
1. SUMMARY OF WATER QUALITY CHARACTERISTICS (continued)
Pre-
test
Sanple
/
/
/
/
/
/
/
/
/
/
/
/
/
/
Post-
test
Sanple
/
/
/
/
/
/
/•
/
/
/
/
/
/
/
Assumec
Na-SO,
Coftc.J
(re/L)
0
752
0
321
0
323
0
319
0
944
0
612
0
970
0
926
0
664
0
1017
0
805
0
292
0
931
0
886
Alkalinity
(ng/L CaOO-j)
93
92
166
190
141
144
192
193
181
192
195
192
193
191
195
192
148
197
191
164
laboratory Results
pH
8.21
7.98
7.15
8.55
8.45
8.70
8.29
8.60
8.07
8.50
8.70
8.22
8.48
8.18
8.60
8.21
7.71
8.43
8.18
8.50
Total
Hardness
(nft/L CaOOj)
216
213
116
127
190
186
118
112
104
117
107
107
119
106
109
104
137
113
112
106
^
CPE/ISO^
681
149
2.3
4
105
719
132
487
1
2
721
4
612
107
846
3
66
847
70
613
T.D.S.
(ne/b
1280
490
384
290
508
1327
468
926
332
286
1268
225
1120
480
1506
318
376
1492
405
1149
Co
(ng/p
0.11
0.03
0.02
0.01
0.02
0.07
Q.07
0.08
<0.01
0.01
0.12
0.01
0,1?
0.02
P-H
0.02
0.02
0.14
0.02
0.06
Fe
JfflS/H
0.08
0.18
0.03
0.02
0.01
0.06
0.06
0.04
0.02
0.06
0.08
0.04
0.10
0,08
0,24
0.04
0.10
0.06
0.08
0.02
Ml
(nK/n
^0.01
0.01
0.01
0.02
0.02
0.02
0.02
0.02
-------
TABLE 1. SUMMARY OF WATER QUALITY CHARACTERISTICS (continued)
Sanple
iate
11/24/79
il/26/79
12/16/79
12/20/79
12/21/79
12/28/79
13/05/79
13/07/79
13/11/79
13/20/79
Manufacturer
Envirex
Envirex
FMC Spargers
FMC Spargers
FMC Spargers
FMC Spargers
FMC Spargers
FMC Spargers
FMC Spargers
FMC Spargers
Water
Batch
Nuiber
3
3
1
1
2
2
3
3
4
4
Pre-
test
Sanple
/
/
/
/
/
Post-
test
Sanple
/
/
/
/
/
Assume
&IK/L)
0
480 *
0
640
0
823
0
653
0
686
Laboratory Results
Alkalinity
(ttR/L CaCO,)
182
182
179
196
195
pH
7.93
7.67
7.50
7.73
7.96
Total
Hardness
(TO/L CaCO,)
106
88
96
105
104
Ta>41
(DK/tsO/)
5
2
675
2
426
T.D.S.
(TO/1^
321
280
1178
307
912
Co
(w/D
<0.01
<0.01
0.06
0.008
0.075
Fe
(n^/L)
0.02
<0.01
0.01
0.08
0.18
tti
On^/I}
0.01
<0.01
<0.01
0.015
0.014
* Calculated values baaed on actual sodium aulfite additions.
-------
made by Ellison Instrument Company). Dual flow measurements were taken to
insure greater accuracy. Furthermore, to provide accuracy over the wide
range of flow rates encountered, two different sized air lines were used,
both with appropriately sized orifice plates and Annubar equipment. A third
and smaller air line was used for two tests on the jet aeration system; this
line was equipped with an Annubar.
The airflow measurement system was designed by staff of the Sanitation
Districts according to References !/> !/,. and i/. Drawings of the orifice
plate and Annubar equipment used are given in Figures 2, 3, and 4. The
pertinent flow equations are shown in Appendix A. It is beyond the scope of
this report to explain the equations in any detail. It is sufficient to say
that the equations contain somewhat complicated terms, many of which are
correction factors and refinements and are often of only minor significance.
These factors were accounted for in the analysis primarily because the flow
calculations were performed using a hand-held programmable calculator.
The differential pressure from the primary elements was measured with
manometers. Air line temperature and pressure, ambient temperature and
pressure, and relative humidity were recorded. The airflow readings were
converted to standard conditions of 20°C (68ar), 101.325 kPa (14.70 psia),
and 36% relative humidity.
Dissolved Oxygen Sample Collection
Sample Locations--
Water samples to be analyzed by the Winkler method^/ were collected
from four locations in the aeration tank (Figure 1). There were two
vertical sampling "stacks", each with two sampling locations.
Schematically, the 6.1-m X 6.1-m (20-ft X 20-ft) tank surface was divided
into four quadrants, labeled 1 to 4 in a clockwise direction. The first
stack was located in the middle of quadrant 1; the second stack was located
between quadrants 3 and 4, halfway between the center of the tank and the
aeration tank wall. Submersible sample pumps were installed in the first
stack at mid-depth and at 0.6 m (2.0 ft) off the bottora of the tank; the
second stack had submersible pumps installed at mid-depth and 0.6 m (2.0 ft)
below the surface of the tank. The heights* of the pumps were adjustable for
proper placement at the various water depths. The sample pump for the
in-line probe was installed near mid-depth on the first sampling stack.
Anti-Air Entrainment Device—
An anti-air entrapment device was installed on each pump to avoid the
collection of air bubbles in the samples. These devices consisted of a
152-mm (6.0-in.) length of 38-mm (1.5-in.) diameter pipe mounted pointing
vertically upward on the suction side of the pump. Theoretically, the
velocity in the suction line was less than the rise velocity of the air
bubbles in the tank to help avoid the collection of bubbles in the water
samples.
11
-------
8 HOLES
EQUALLY SPACED-
13/16 DIAMETER
1/8 THICK
-STAINLESS
STEEL
i
1.512" 1
1 ^
/
\
v \ /
\
\
f
I/ii" DIAMETER-
BORE TO 1.698 I.D.
-BEVEL EDGE AT A 45*
ANGLE TO 1/16 THICKNESS
Figure 2. Orifice plate for 3-in.air line.
12
-------
8 HOLES
EQUALLY SPACED
3/4" DIAMETER
I/16" DIAMETER
1/8 THICK
STAINLESS
STEEL
BORE TO 2.777 l.D.
NO BEVEL
NECESSARY
Figure 3. Orifice plate for 4-in.air line.
13
-------
3 Different Annubars were used for the Aeration
Equipment Evaluation (3/4", 2",and 3" pipe sizes)
(Courtesy of Ellison Instrument Co,}
Figure 4, Annybar flow measurement device.
14
-------
Sampling Devices--
D.O. was measured by two methods. These two methods consisted of 1) an
in-line mounted D.O. probe/analyzer and 2) sample collection and analysis.
In both cases, samples were pumped through plastic tubing by submersible
pumps from the aeration tank to the sampling station. At the sampling
station, the water was discharged through sampling devices into a steel drum
and pumped back into the aeration tank. The D.O. probe/analyzer was
mounted in the line just upstream of the discharge nozzle. This apparatus
allowed instantaneous measurement of aeration tank D.Q. concentrations. The
other four pumped samples were used for sample collection in "BOD"-type
bottles. Copper discharge nozzles for the four pumped samples were mounted
on a plywood board to enable one operator to control the four samples
simultaneously. Each nozzle consisted of a 9.5-mm (3/S-in.) I.D. copper
tube and a valve for flow regulation. These nozzles were mounted so they
fitted easily into four BOO bottles when fully inserted, and there was room
at the neck of the BOD bottles for the displaced air to escape during
filling.
Sample Collection Procedure—
An attempt was made to collect approximately eight samples for the
Winkler analysis between 2Q% and 80% saturation, although additional samples
were taken below 20% and above 80% saturation. Time was monitored with a
stopwatch. Sample water was pumped continuously to purge the BOD bottles
until the desired time "t", after which the sampling device was withdrawn
and the BOD bottles stoppered. If necessary, 1 or 2 sec were allowed before
stoppering the BOD bottles to allow any small air bubbles to rise to the
surface and escape. The overflow water from the BOD bottles was caught in a
208-L (55-gal) tank and was continuously pumped back to the aeration tank.
Sampling Rates--
The submersible pumps for the Winkler samples were sized so a BOD
bottle could be filled three to five times in 15 sec (0.06 to 0.10 L/sec =
1.0 to 1.6 gpm). This was done to insure adequate displacement of the water
in the BOD bottle and to minimize the detention time in the sample lines
(approximately 10 sec). All pump rates and sample line lengths-were equal
so that the samples from the various locations would represent the same time
"t". Furthermore, the velocity of the water into the BOD bottles was kept
below 1.5 m/sec (5.0 ft/sec) to avoid air entratnment upon insertion or
withdrawal of the copper nozzles in the bottles.
The sampling rate for the in-line probe was approximately 0.28 L/sec
(4.5 gpm). This rate was chosen to minimize fluid pressure on the probe
while maintaining an adequate velocity of water past the probe tip.
15
-------
Di SSQ]yed Oxygen Measurements
The official D.O. measurements were made by the Winkler method on
captured samples. The azide modification of the Winkler titration method
was used with alkali-iodide-azide reagent #2 as stated in Standard
Methods.!/ This reagent was selected because it reportedly reduced the
volatility of iodine and thus provided a more accurate D.O. measurement.
Samples were set up immediately after capture and titrated within 1.5 hr.
The thiosulfate used for the titrations was standardized once each day. Two
burets were available to titrate the Winkler samples in an effort to
expedite the procedure.
In the study, it was recognized that Winkler titrations may be affected
by agents that either oxidize iodide to iodine or reduce iodine to iodide.
Two steps were taken to insure that the occurrence of such interferences
would not take place unknowingly. The first was to measure the D.O.
saturation level before and after each test by both the Winkler (iodometric)
method and the electrometric method (using a 0.0. probe/analyzer). The
second step was the daily evaluation of interferences using a blank. In
this method, the iodine present in a sample of tank water (with iodide salt
added) was measured to detect any positive interference (oxidation of iodide
to iodine). No interferences were detected during the study.
The in-line D.O. probe was calibrated by the air calibration method. A
BOD bottle was filled approximately 1/4 to 1/3 full with tap water. Time
was allowed for the contents of the bottle to equilibrate with the ambient
temperature. The bottle was stoppered and shaken vigorously to saturate the
water with oxygen. The stopper was then removed, allowing fresh air to
enter the bottle. The bottle was restoppered and shaken vigorously again,
this time to saturate air with water vapor. The probe was then inserted
into the bottle. Time was allowed for the probe thermistor to equilibrate
with the air temperature in the bottle before measuring the temperature and
setting the corresponding D.O. saturation.!/ Finally, the probe was
adjusted for the salinity correction of the tank water. Salinity was
assumed to be the initial water batch TDS plus TDS addition as sulfate.
This adjustment was a minor correction.
The D.O. measurements from the D.O. probe were recorded with a strip
chart recorder. Care was taken to check the recorder's calibration and zero
indication.
Aerator Power Determinations
In addition to power for an air supply, aeration equipment may also
require power for a mixer or a pump. Of the eight systems evaluated in this
study, only the jet aeration system required pump power in addition to the
power for the air supply. The following power determination discussion is
divided into two subsections, Air Power and Pump Power.
16
-------
Air Power--
Due to the fact that the test facility blowers operate at a fixed
speed, it was necessary to "waste" air to obtain the desired airflow rates.
This means that no direct measurement of air horsepower was possible. Air
power was calculated by the adiabatic compression equation using measured
airflow, measured diffuser static head, and assumed suction and pressure
losses.
The following relationship was used to determine air power. Pressure
losses on the suction side of the blower were estimated by the relationship:
Pa = 0.005729 (Ya1r) (Q) (Tt + 460)
0.2S3
- i
(i)
in which:
Pa - air power, hp
= specific weight of air at the temperature, pressure,and
relative humidity for which Q is reported, lb/ft3
air
Q = airflow rate, cfm
TJ = blower inlet temperature, °F
pi = blower inlet pressure, psia
P2 - discharge pressure, psia
Air power is that power associated with the blower portion of the
aeration system. Reference can be made to nominal, delivered, brake, or
wire power for the air blower. These various powers are described in the
following paragraphs.
Air nominal power—The aeration equipment evaluation was based on
testing at one of two power density ranges, either 13.2., 26.3, and 39.5 W/m3
(0.5, 1.0, and 1.5 hp/1000 ft3) or 7.9, 13.2, and 26.3 w/m3 (0.3, 0.5, and
1.0 hp/1000 ft3). These power density ranges were based on nominal and not
delivered, brake, or wire power. Nominal power, which does not account for
certain system-specific headlosses, was the most appropriate parameter on
which to control power in the study because it more closely approximated the
power delivered to the basin. Air nominal power is calculated using the
adiabatic compression equation. In the nominal power determination, blower
inlet pressure is assumed to be 100.6 kPa (14.60 psia). Also assumed in the
calculations is that the discharge pressure is the diffuser submergence.
The following relationship is used to determine air nominal power:
ans
- 0.227 Q
i
Pan + Pch (.491)
Pi
17
•r
283; .
(2)
-------
in which:
pans :
air nominal power at standard conditions of 20°C (68°F),
101.3 kPa (14.70 psia), 36% relative humidity, and a
blower inlet pressure of 100.6 kPa (14.60 psia), hp
pao = barometric pressure at standard conditions, 101.3 kPa
(14.70 psia), psia
Psh = aerator static head, in. of mercury
Pi = assumed blower inlet pressure, 100.6 kPa (14.60 psia), psia
Air d e 1 i ye red power—Air delivered power is considered to be the
theoretical adiabatic power required at the blower to supply air through a
diffuser system operating under a given static head. In determining the air
delivered power, various headlosses are taken into account that were
previously ignored in the evaluation of air nominal power. These headlosses
include estimated aerator headloss, estimated system piping headloss, and
estimated blower suction headloss. Aeration headloss values included here
are those values that were actually measured in the study. Aeration system
piping headloss and the blower suction headloss were both estimated using
relationships presented below.
In this study, air delivered power is reported in terms of standard
conditions of 20°C (68°F), 101.3 kPa (14.70 psia), and 36% relative humidity.
The following equation is used for determining the air delivered power
values:
Pads = 0.227 qtest
0.283
- 1
(3)
in which:
Qtest = average airflow rate associated with a test, scfm
Pads = air delivered power at standard conditions of 20°C (68°F),
101.3 kPa (14.70 psia)r and 36% relative humidity, hp
The only question remaining in this equation is the values to use for
PI and p2- The blower inlet pressure, pj_, is determined according to the
following equation:
= Paa - nLs
(4)
18
-------
in which:
h|_s = estimated suction piping headless, psi.
This estimated headloss value is determined using the following
relationship:
in which :
Qmax = maximum test airflow rate for a system at each water
depth, scfm
The parameter h[_s was determined for each test. At each depth, a
manufacturer was assigned a 0.7-kPa (0.1-psig) suction headloss at the
maximum airflow rate. The values of the suction headlosses at the lower
power levels were obtained according to a square root relationship with
airflow rate. This was done to simulate losses that resulted from a diurnal
variation in airflow.
The blower discharge pressure, p£, is determined according to the
following equation:
P2 " Pao + O-491 Psh + °-0351 nL + nLd
in which:
psn = aerator static head, in. of mercury
h[_ - measured diffuser headloss, in. of water
= estimated aeration system piping headloss, psig
The estimated headloss value is determined using the following
relationship:
/'QtestY
I \ (7)
Actual field measurements of static head and diffuser headloss
are used in Equation 6 above.
The discharge piping headloss, h^, is determined in a manner similar
to the suction piping headloss. Each aeration system is assigned a 6.9-kPa
(1.0-psig) line loss corresponding to the maximum airflow at each depth.
19
-------
The values of the discharge piping headless at the lower power levels are
obtained according to a square root relationship with airflow rate. As with
the suction piping headless, this is done to simulate losses that result
from a diurnal variation in airflow.
Air brake power—Air brake power is usually considered to be the power
required at the output shaft of the blower motor (Figure 5). Standard air
brake power is determined from standard air delivered power by the following
expression:
Pads
pabs = eb.ed
in which:
^abs = air brake power at standard conditions of 20°C (68°F)
101.3 kPa (14.70 psia), and 36% relative humidity, hp
eb = blower efficiency, decimal %
e
-------
ro
GAS HORSEPOWER
WIRE
HORSEPOWER
MOTOR
MOTOK
BRAKE
HORSEPOWER
DRIVE
BLOWER
BRAKE
HORSEPOWER
BLOWER
-------
Pump Power—
Pump power is the power associated with the pump portion of an aeration
system. In this study, only one system, the jet aeration system, used a
pump. Because the jet aeration system employed a pump in addition to a
blower, a suitable method for determining pump horsepower had to be
developed.
Pump delivered power—To determine pump delivered power, the following
procedure was used. During each test, determinations were made of the pump
total dynamic head. This information was then used with the manufacturer's
pump performance curves to determine pump flow rate. Using this flow rate,
the following equation was used to determine pump power:
Qp (ywater) (TDH) a0)
Ppd = 550
in which:
ppd = pump delivered power, hp
\ater = specific weight of water, 62.4 lb/ft3
TDH = total dynamic head, ft of water
Qp = pump discharge, cfs
*
Pump brake power—The pump brake power is considered to be the power
required at the output shaft of the pump motor (Figure 5). The standard
pump brake power is determined from the standard pump delivered power by the
following expression:
Ppb = Ppd/(ep)(ed) (11)
in which:
Ppb = PumP brake power, hp
ep - pump efficiency, decimal %
ed = drive or coupling efficiency, decimal %
For the purposes of this study, the pump efficiency assumed is 0.805.
This is an average of typical efficiencies for full-scale submersible and
dry pit pumps. The drive efficiency assumed is 0.95. Thus:
22
-------
Ppb = Ppd/C(0-805(0.95)] = Ppd/0.765
Pump wire power — The pump wire power is considered to be the
electrical power required to run the pump motor (Figure 5). The standard
pump wire power is determined from the standard pump brake power by the
following relationship:
Ppw = Ppb/era d2)
in which:
Ppw - PumP wire power, hp
em = motor efficiency, decimal %
For the purposes of this study, the motor efficiency assumed is 0.92.
Therefore:
Ppw = Ppb/0-92 « Ppd/C(0.92)(0.765)j = Ppd/0.704
Direct watt meter readings were also recorded during the jet aerator
testing. They were not used in determining the results presented in this
report because of problems associated with readability and assumed pump
efficiencies. Additional information on the estimation of pump power can be
found in Section 7.
For the jet aeration system, the total power requirements are the sum
of the air and pump horsepowers.
Power Densjty
Power density is the power input per unit volume of aeration tank
liquid. Power density is a term that makes the comparison of test results
at different volumes possible. It was used in this study for both test
control and comparison of results for the tests conducted at various
aeration tank water depths. In general, power density is calculated
according to the following equation:
PD = PUOOOWi (13)
in which:
PD = power density, hp/1000 ft3
P - power, hp
Vj = inflated water volume, ft3
In addition to SWD, nominal power density (from Equation 13 on a
nominal power basis) was chosen as a control parameter. In this study, the
aeration equipment manufacturers were given a choice of two nominal power
23
-------
density ranges: 7.9, 13.2, and 26.3 W/m3 (0.3, 0.5, and 1.0 hp/1000 ft3) and
13.2, 26.3, and 39.5 W/m3 (0.5, 1.0, and 1.5 hp/1000 ft3). Adjustment of the
power density was accomplished by increasing or decreasing airflow to the
aeration tank. When the specified nominal power density was set, the test
was run. As in the equation above, standard nominal power density is
calculated as follows:
in which:
PDns
Pns
(14)
nominal power density at standard conditions, hp/1000 ft3
total nominal power at standard conditions of 20°C
(68°F), 101.3 kPa (14.70 psia), 36% relative humidity,
and a blower inlet pressure of 100.6 kPa (14.60 psia), hp
Nominal power density is a term well suited as a controlling parameter
in the study. However, for purposes of taking into account additional
effects representative of actual system operation, the term "delivered power
density" was developed. This value takes into consideration additional
power loss factors due to blower suction loss, air piping headless, and
aeration device headless. While headlosses for the aeration devices are
actual measurements, the piping headless and blower suction loss are
estimated values (Equations 5 and 7). The effects of diurnal variation are,
therefore, more accurately reflected in the delivered power density
expression. Delivered power density is defined to be the delivered power
divided by the inflated liquid volume in the aeration basin. Determination
of delivered power density is made using the following equation:
in which:
= delivered power density at standard conditions, hp/1000 ft3
= total delivered power at standard conditions of 20°C
(68°F), 101.3 kPa (14.70 psia), 36% relative humidity,
and a blower inlet pressure of 100.6 kPa (14.60 psia), hp
H e ad 1 os s Me as u r emen t s
Aerator headless was determined by subtracting aerator pressure from
the static head using a differential water-filled manometer. The static
head was determined with a bubbler system. The bubbler system consisted
of a small air pump and a discharge pipe. The air pump provided a constant
supply of air to the pipe that discharged at the aerator air release point.
The pipe was large in diameter and the airflow rate low so that there were
no pressure losses in the piping. A pressure tap was made in the pipe so
24
-------
that this "bubbler pressure" could be measured. The pressure measured with
the bubbler device is also referred to as the static head. A second
pressure tap was installed in the center of the air distribution piping for
the measurement of aerator pressure. A manometer was used to measure the
headless (the difference between the diffuser pressure and the static head).
Additional measurements included aerator pressure, aerator air temperature,
and water temperature.
If the air supply had been shut off, when air was resupplied to the
aeration system, the aeration system was first blown out at a high air rate
for at least 15 min. After that, a minimum of 30 min at the proper air rate
was maintained before the headloss readings were taken.
Deoxygenation Procedure
Cobalt chloride was used as a catalyst in the deoxygenation reactions.
It was added once at a dosage of 0.1 mg/L as cobalt ion to each batch of
test water. The chemical crystals were added to the mix tank and allowed to
dissolve for at least 30 min prior to discharging the solution into the
aeration tank. After cobalt addition to the aeration tank, at least another
30 min was allowed prior to the start of the first test.
Anhydrous sodium sulfite was used to deoxygenate the water prior to the
start of each test. The amount of sodium sulfite added was approximately
1.5 times the stoichiometric requirement for oxygen removal. The salt was
dissolved in approximately 379 L (100 gal) of water prior to the start of
each run. The brine addition to the tank was accomplished within a 2 min
period. The solution was pumped equally into the four tank quadrants
through a 4-hose addition system. Distribution was, therefore, as even and
rapid as possible. The chemical mix tank and delivery hoses were
immediately flushed with tap water to wash all residual sodium sulfite into
the aeration tank.
A decision was made to discard each water batch after the accumulated
sodium sulfite concentration had reached 1000 mg/L. At that time, samples
were taken for laboratory analyses to determine the chemical properties of
the "post-test" water. Analyses were also conducted prior to using a water
batch to determine the "pre-test" condition. These measurements included
pH, alkalinity, hardness, sulfate, total dissolved solids, cobalt, iron, and
manganese. A presentation of these results was given previously in Table 1.
FIELD EXPERIMENT PROCEDURE
Each field experiment was conducted according to the rigid step-by-step
procedure itemized below.
1. Collect a water sample for laboratory analysis prior to the first
test on a batch of water.
2. Prior to a given test, run a high airflow rate through the
aeration system for approximately 15 min.
25
-------
3. Set the aeration tank water level at the approximate depth
desired.
4. Set the airflow rate to the approximate power level under
investigation.
5. Adjust the water level to the desired depth.
6. Measure the aeration tank static head with a bubbler device.
7. Calculate the exact airflow rate required for the test.
8. Set the airflow rate to the desired value and maintain these
conditions prior to the start of the test.
9. Add the cobalt chloride (if required) in solution form to the
aeration tank water.
10. Mix the required amount of dry sodium sulfite with water in the
mix tank.
11. Position the sampling pumps at the proper elevations.
12. Adjust the chemical distribution hoses so that they discharge
just above the surface of the water.
13. Adjust the BOD bottle fill rates so the bottles are filled in 3
to 5 sec (0.06 to 0.10 I/sec = 1 to 1.6 gpm). Also adjust the
in-line probe sampler flow rate so that it is approximately 0.28
L/sec (4.5 gpm}.
14. Prior to the first official test on a new water batch,
deoxygenate the water with the sodium sulfite solution and
reaerate it back to saturation. Prepare another batch of sodium
sulfite solution for the official test.
15. Determine the normality of the sodium thiosulfate for the
(Winkler) D.O. measurements.
16. Check the condition of the in-line D.O. probe membrane.
Calibrate the probe and record the pre-test D.O. reading.
17. Check the condition of the D.O. probe strip chart recorder.
IS. Collect a pre-test equilibrium sample from each sample location.
19. Compare the pre-test equilibrium values from all sources.
20. After a minimum of 30 min and just prior to the start of the test,
record
26
-------
a. ambient temperature, barometric pressure, and relative
humidity,
b. flow meter differential pressure (both Annubar and orifice
plate), line temperature, line pressure, Annubar stagnation
pressure, and manometer board temperature,
c. blower differential and discharge pressure,
d. air temperature at the aerator,
e. aerator headloss,
f. aeration tank water temperature,
g. aeration tank water level,,
h. aerator static head, and
i. pump power measurements (pump discharge pressure).
21. Turn on the D.O. strip chart recorder, and set the 0.0. probe to
the proper scale.
22. Add the sodium sulfite solution, and flush the chemical lines
with tap water.
23. Monitor the 0.0. level in the tank with the in-line probe. Make
sure that the tank D.O. remains at zero for a minimum of 2 min
(the estimated time required for complete mixing of sulfite to
occur).
24. .Start the test when the D.O. level begins to rise (indicated by
the in-line probe).
25, Collect samples at the preselected time intervals.
26. Add the first two Winkler reagents (manganese sulfate and
alkali-iodide-azide) as soon as possible. Shake the samples,
allow them to settle half-way down in the bottle, and then shake
again.
27. Take a second set of readings at the end of the run (the same
readings as those shown in Step 20 above).
28. Acidify, shake, and titrate all the Winkler samples. This step
starts as soon as possible.
29. Determine if there are chemical interferences in the Winkler
method
27
-------
30. After there has been no increase in the recorded D.O. for a
period of at least 15 min, collect a set of equilibrium samples.
31. Perform a Winkler analysis on the final samples.
32. Read and record the D.O. probe reading on the aeration tank
water. Compare this with the recorder reading. Check the
recorder zero.
33. Compare the equilibrium results from all sources.
34. Photograph the aeration system in operation.
35. Shut off the blower and accessory aeration equipment (i.e., jet
system pump).
36. Measure the non-aerated tank water level.
37. After the last test run for a given water batch, collect a water
sample for laboratory analysis.
28
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SECTION 4
OXYGEN TRANSFER DATA ANALYSIS
FIELD MEASUREMENTS
The majority of the field measurements were collected both before and
after a test, primarily to insure that test conditions remained steady and
sometimes to determine an average value of the parameter. An "arithmetic"
average was used in this study for a particular variable if it was felt that
the variation observed was random; a "time" or "weighted" average was used if
it was felt that the variation observed was non-random. Water level
measurement is an example of a parameter that was arithmetically averaged
during a test. Airflow measurement is an example of a parameter that was
time averaged during a test.
Time averages are calculated assuming that the measured parameter varies
in a linear fashion from the start to the end of the run. The value of the
variable at any time t is then calculated according to a linear
interpolation. For the purposes of this study, t is taken to be the time
midway between the start and finish of the water sample collection. The
field measurements taken during each test along with other pertinent
information associated with the measurements are summarized in Table 2.
Several measurements deserve special mention. Winkler D.O.
measurements were obtained an samples from four locations. Each location was
analyzed separately; no averaging of the four 0.0. data values at a given
time t was done. The data between 20 and 90% 0.0. saturation were used in
the final analysis with both analysis methods. Note that the data truncation
used in the final analysis was different from that applied in the initial
evaluation of test data (20 to 80% D.O. saturation). This change was made
to accommodate the evaluation of data by an analysis method that requires
D.O. data near saturation. Two different flow measurement elements were
used to measure airflow rates. Airflow measurements were taken with these
elements both before and after each run to insure accuracy. One of the
devices was an orifice plate; the other was an averaging pitot tube called an
Annubar. The time-average airflow rate was first determined for each flow
meter. An arithmetic average of these two time-averaged airflow rates was
then used in the oxygen transfer calculations.
BASIC THEORY
The transfer of a gas into a liquid can be described by the two-film
-------
TABLE 2. FIELD MEASUREMENTS
Measurement Symbol Units
water depth
(inflated) zj ft
water depth
(deflated) z
-------
TABLE 2. (continued)
Measurement Symbol Units
annubar flowing
gas pressure pfa
annubar stagnation
pressure pt
orifice plate
differential
pressure h0
annubar
differential
pressure ha
aerator
static head psf,
aerator headless h[_
blower discharge
pressure pj
blower
differential
pressure p^
pump discharge
pressure TDK
barometric
pressure pa
relative
humidity R.H.
pump wire
power Ppw
1.8 = before test,
2. AR = arithmetic, T
in. Hg
in. Hg
in. H20
in. H20
in. Hg
in. H20
in. Hg
in. Hg
in. H20
mm Hg
*
kW
A - after
~ time.
Frequency ^ Measurement Type 2
of Devices of
Measurement Used Average
B/A
B/A
B/A
B/A
B/A
B/A
B/A
B/A
B/A
(jet aerator
only)
B/A
B/A
continuous
test, B/A = before
I
1
1
1
1
1
1
1
1
1
1
1
and after test.
none
none
none
none
AR
T
none
none
none
T
T
T
-------
theory proposed by Lewis and Whitman. U This theory is expressed by the
following mathematical relationship:
dC/dt -
in which:
dC/dt = oxygen transfer rate per unit volume, mg/L/hr
= overall volumetric mass transfer coefficient
for test conditions, 1/hr
C* = D.O. saturation value, mg/L
C = 0.0. concentration, mg/L
This is the differential form of the basic equation and states that the
oxygen transfer rate per unit volume is directly proportional to the 0.0.
deficit (C* - C). Note that dC/dt is greatest when C is assumed to be zero.
The mass transfer coefficient, K^a^, is a function of many variables,
including the type of aerator, the aeration tank geometry, the nature of the
liquid, and the liquid temperature. Equation 16 was originally developed to
describe the oxygen transfer in small, shallow containers. It has been
generalized to the case of large, deep aeration basins that are completely
mixed. If complete mixing is not achieved, the use of Equation 16 to define
the oxygen capabilities of the aeration system may lead to significant
errors. The relationship embodied in this equation, therefore, constitutes
the basic mathematical model describing oxygen transfer, if the assumption of
complete mixing is accurate.
All data analysis methods share one common trait; they define an
analytical procedure to calculate oxygen transfer rate. This always includes
the fundamental determination of both the volumetric mass transfer
coefficient, K|_at, and the D.O. saturation value, C*.
Eight data analysis methods were originally planned to be incorporated
in this report. The methods included three that use the integrated or
log-deficit form of the basic equation: the Mid-Depth, Surface, and
Equilibrium Measured methods. Also planned was a single method that uses the
transformed integrated form of the basic equation, the Exponential method.
The final four methods use the differential form of the basic equation for
parameter determination. These four are the Direct, Log Mean Driving Force,
Log Mean Saturation, and Equilibrium Corrected methods of analysis. A
computer program was developed to analyze data using all eight methods. It
was, however, decided to include only the analysis results of the two most
highly regarded methods. This decision was based on a review of the results
of the various methods, the difficulties involved in presenting results from
each method, and a wish to not confuse the reader regarding the primary
purpose of this study - an evaluation of the oxygen transfer performance of
various generic aeration systems. The two methods the Districts considered
to be the most highly regarded were 1) the log-deficit model with a measured
32
-------
equilibrium, hereinafter to be referred to as the Equilibrium method, and 2)
the Exponential model.
The differences between primary data analysis methods include
1, the form of the basic mathematical relationship on which a regression
analysis will be run,
2. the method for determining C*,
3. the use of a correction for gas-side oxygen depletion''' (no
correction is used in either the Exponential or Equilibrium
methods), and
4. data truncation requirements.
At least three forms of the fundamental relationship expressed in
Equation 16 are used for the analysis of clean water test data. These are
the differential, integrated, and transformed integrated equation forms. It
is in the differential form of the basic equation that Equation 16 is
expressed. In the Equilibrium method analysis, the integrated equation form
is used. The Exponential method analysis uses the transformed integrated
equation form. Detailed information on the methods of analysis used in
determining the study results follows.
The differential form of the basic equation can be rearranged and
integrated to obtain the "integrated" or "log-deficit" form. In the past,
this form of the equation has been the most commonly used. After
rearrangement, Equation 16 becomes:
dC/(C*-C) »
Letting D = C*- C and assuming C* is constant:
-dD/D = KLat(dt)
Upon integration between (t-f, D-j) and (tf, Of), this becomes:
Df
In D
= - K[_at (t)
*i
in which:
DI = initial 0.0. deficit, mg/L
Df = final 0.0. deficit, mg/L
t Gas-side oxygen depletion is defined as the decrease in a bubble's oxygen
purity as it rises through the aeration tank.
33
-------
Substituting for D;
In (C*-Cf) - In (C*-C-j) = - KLat (tf-tt)
or:
In (C*-Cf) = - KLat (tf-tj) + In (C*-C-j) (17)
in which:
Ci = initial D.O. concentration, mg/L
Cf - final D.O. concentration, mg/L
This is the integrated form of the basic equation. It is this form that
is used by the Equilibrium method. In the analysis of data, t^ is 0, tf is
total elapsed time t, and Cf represents the various C values corresponding to
values of t. Making these assumptions, the relationship between C and t is
as follows:
In (C*-C) = - K|_at(t)/3600 + In (C*-Cj) (18)
This is the exact equation used in the Equilibrium method data analysis.
A conversion factor of 3600 is used to make compatible the units of K|_a,
1/hr, and t, sec.
The second method used in this report is referred to as the Exponential
method. An exponential form of the equation has been favored by the ASCE
Subcommittee on Oxygen Transfer Standards.°/ Equation 17 can be transformed
to obtain the exponential form of the basic oxygen transfer relationship.
From Equation 17, it follows that:
e In
-------
Again, a conversion factor of 3600 is used to make compatible the units
of K[_a, 1/hr, and t, sec.
The fundamental curves associated with the above two forms of the basic
oxygen transfer equation are shown in Figure 6. While the Equilibrium method
employs a linear curve fitting technique, the Exponential method requires the
use of a non-linear curve fitting technique.
The method of determining C* is the major difference between various
data analysis techniques. The specifics of the C* determination used in this
study are discussed in the next subsection. Suffice it to say at this time
some models use a "measured" value while others use a "derived" value.
"Measured" means the saturation value is experimentally measured in the
field. "Derived" means the saturation value is derived from the data by a
curve fitting technique. The Equilibrium method uses a measured saturation,
while the Equilibrium method uses a derived saturation.
DETERMINATION OF KLat AND C*
For both methods, the measured oxygen transfer data (C,t) for each of
the four sample locations are analyzed separately. The resulting Kj_at and
C* values for the individual sample locations are then averaged to obtain the
K|_at and C* results.
According to Equations 17 and 18, Kj_at is the negative slope of the
straight line through a semi-logarithmic plot of the test data. Data plotted
on the ordinate axis is the natural logarithm of the D.0» deficit, while
time is plotted on the absissa (Figure 6). A linear least squares regression
analysis is used to determine the line of best fit.
The Equilibrium method assumes that the appropriate C* in Equations 17
and 18 is the measured equilibrium D.Q. concentration. In practice, the
clean water test is conducted until D.O. saturation is observed (no further
change in the D.O. concentration). A time equivalent to 6/KLat is usually
sufficient to achieve this condition.!.'' Equilibrium samples are taken at
each of the four sample locations in the tank.
With Equations 19 and 20, a non-linear least squares regression analysis
is required to determine the best estimate of the parameters Ki_at» C*, and C}
(Figure 6). As opposed to the Equilibrium method, the Exponential method
does not assume the C* value; instead the value is derived from the data.
This equation form, however, assumes that C* is constant throughout the test
(no correction for gas-side oxygen depletion).
Numerous non-linear optimization techniques could be used to
determine the best estimates of the parameters Ci, C*, and ^Lat- All
these techniques should yield approximately the same results. For
purposes of this study, analysis was done using the Complex Method of
Box technique .IP./
35
-------
!n{C* -Ci)
o
EQUILIBRIUM METHOD
In (C* -C)= -KLat (t)-Hn(C* -Cj)
t, hr
EXPONENTIAL METHOD
= C*-(C*-Ci)e"KLat(t)
2/KLa 4/KLa 6/KLa
t, hr
Note: The saturation values were directly measured for the Equilibrium
method and analytically derived for the Exponential method.
Figure 6. Primary curve plots for Equilibrium and Exponential data
analysis methods.
36
-------
LEAST SQUARES REGRESSION METHODS
A regression analysis is normally of the linear least squares variety,
but it may also be performed using non-linear techniques. A linear least
squares regression of data defines one straight line. This straight line
is specified by the constraints that the sum of the deviations (vertical
distances between the data points and regression line) must equal zero and
the sum of the deviations squared is the minimum value. In the log-deficit
form of the gas transfer equation, a linear regression is employed
(Equations 17 and 18). In this analysis, the ordinate axis is represented
by the natural log of the oxygen deficit (difference between measured
oxygen concentration and the saturation value). Time is plotted on the
abscissa. The resulting slope of the "best fit" straight line is -K|_at-
The Exponential method defines the non-linear relationship between C and t
to be a function of three constants, C*, C^ and K^a^. Non-linear
regression analysis is used to define these'three values. In the case of
the non-linear least squares analysis, a number of different optimization
techniques may be applied. For the non-linear least squares analysis, the
objective is that the sum of the initial deviations squared equal the
minimum value. In the Exponential method of analysis, the ordinate axis
represents the measured D.O. concentrations. The corresponding values of
time are plotted on the abscissa. The determination of the best fit line
is accomplished by an iterative searching technique referred to as the
Complex Method of Box.IP_/
The Complex Method of Box is used here to determine the values of Ci,
C*, and K[_at that best describe the relationship (Equations 19 and 20)
between time and D.O. As with a linear regression, the objective here is
to minimize the sum of the squares of the deviations (SSD). (Deviations
are the differences between calculated and measured values of D.O.) SSO is
defined by the following expression:
SSD = JjCc-Cn,)2 (21)
in which:
Cc = C* - (C*-Ci)
and:
Cm = measured values of D.O. concentration, mg/L
Consider a point with coordinates (Ci, C*, K|_at). This point can be
evaluated in terms of SSD to show how well the point describes the
relationship between time and measured D.O. concentration: the lower the
value of SSD, the better the relationship. Note that if all calculated
D.O. values are exactly equal to the measured values of D.O., then
SSD = 0.
The Complex Method of Box is a technique for selecting new points for
SSD evaluation. To begin the process, six different arbitrary points are
37
-------
chosen, each with coordinates (C-j, C*, K|_at). The six points are then
evaluated in terms of SSD. From this group of points, the worst point, Pw
(largest SSO value), is then identified and set aside. Using the remaining
five points, the centroid, PCi is determined. The coordinates of the
centroid are the mean values of Ci, C*, and K^a-t. For the five points in
the next step, the program searches for a new sixth point, one with a SSD
less than Pw. The new point is located on the line that runs through both
PH and Pc. The distance between Pc and the new point is 1.3 times the
distance between Pw and Pc, This new point is located on the side of Pc
opposite Pw. After determining the coordinates of this new point, it is
evaluated in terms of SSD. If the SSD of the new point is not less than
that of PWj a second new point midway between the first new point and Pc is
chosen and'evaluated. This process continues until an improvement in SSD
(better than SSD of Pw) is accomplished. When a better point is
determined, it is placed in the group and the six points are reviewed to
identify the new worst point and the search for a replacement point is
again started.
To determine the final values of Cj-, C*, and K|_at» the process
requires over 300 iterations (the determination of over 300 new points).
In a few instances (less than 1$ of the time), the method may produce
erroneous values for the parameters. However, when an error does occur, it
is substantial in magnitude; detection requires only a brief review of
results. The correction of errors requires only changing the value of one
of the six original starting points and reanalyzing the data.
NEED FOR DATA TRUNCATION
Most all data analysis methods require data truncation near the start
of the test and then again at the end of the test, near equilibrium. The
truncation near the start of the test (low D.O. values) is done primarily
because of problems with sulfite distribution and because of the very high
initial oxygen transfer rates. The truncation at the end of the test (high
D.O. values) is done because near equilibrium, the D.O. may oscillate up
and down very slightly with time.. This can result in the calculation of
negative driving forces and transfer rates, resulting in improper
computational commands during electronic data processing.
One method is different from all others in this regard. The
Exponential method not only does not require but should not have data
truncation near equilibrium. These D.O. values are used in establishing
the final equilibrium value. Furthermore, with the Exponential method, the
data near the start of the test have si-gnificance in describing the
adequacy of the method. The final oxygen transfer result for the
Exponential method, however, should be reported identifying the data (if
any) that have been truncated.
38
-------
The low and high cut-off points for truncation are usually referred to
in terms of percent of D.O. saturation. For this study, the low cut-off
point was 20% and the high cut-off point was 90% of the measured saturation
value. These truncation limits were chosen so that the results of analysis
by both methods would be based on the same data, even though ideally no high
cut-off point for the Exponential method analysis would have been preferred.
It is important to point out that while the determined values of _
and C* may be substantially different for some of the data analysis methods,
it is possible that the product (K|_at)(C*) may be very similar for many of
the methods. It is this product, the volumetric transfer rate, that is
really the important result from the clean water test. It is hoped that this
study will help to show how two methods can provide similar transfer rate
results as well as similar Ka and C* results.
PARAMETERS AT STANDARD CONDITIONS
Once Ki_at an^ C* are determined for a test using a particular data
analysis method, it is possible to make the oxygen transfer rate and
efficiency calculations. Normally, test results are reported in terms of
standard conditions of 20°C (68°F), 101.3 kPa (14.70 psia) and 0 mg/L D.O.
(implies maximum driving force). To calculate oxygen transfer results in
terms of standard conditions, it is necessary to determine each parameter at
standard conditions (K|_a20 ancl C*0).
Determination
The basic oxygen transfer equation is used to make oxygen transfer rate
determinations:
dC/dt = KLat (C*-C) (16)
Normally, the values expressed in this equation are presented in forms
of standard conditions and expressed as follows:
dC/dt = K|_a2o C*0 (22)
One relationship between K[_at and KI^Q tnat is commonly used IP7 is:
KLat = KLa2o (8)V20 (23)
in which:
= overall volumetric mass transfer coefficient at 20°C, 1/hr
9 * KI& temperature adjustment factor
Tw = water temperature, °C
39
-------
The value of 6 used for this study was 1.024. In reality, the temperature
variation in K]_a has been shown to be a function of the type of aerator, as
well as other factors. Due to the lack of available information on this
subject, however, a decision was made to use Equation 23 with 8 = 1.024 for
all the aerators tested in this study.
When Equation 23 is substituted into Equation 16, the basic oxygen
transfer relationship becomes:
dC/dt = KLa20 (C*-C) 1.024 Tw'20
At standard conditions of 20°C (68°F), 101.3 kPa (14.70 psig), and 0 mg/L
0.0. (maximum driving force), the equation reduces to:
(dC/dt)0 = KLa20 C*0
in which:
(dC/dt)0 = standard oxygen transfer rate per unit volume at
standard conditions, mg/L/hr
C*0 = projected field 0.0. saturation value at standard
conditions, mg/L
C*0 Determination
The correction of C* to standard conditions is somewhat more involved.
The D.O. saturation value, C*, for a given aeration system in a given tank
under a given set of operating conditions is a complex function of
temperature, pressure, and oxygen purity. However, assumptions can be made
that make an estimation of C*0 possible. The actual procedure used is a
function of the particular data analysis method employed; for the two
methods used here, only one procedure is necessary.
The following procedure applies to data analysis methods that employ
either a "measured" or "derived" D.O. saturation value. In this procedure,
it is necessary to postulate a relationship between the measured or derived
saturation value (at temperature T and pressure Pa) and the saturation
value at standard conditions [20°C (6S°F3 and 101.3 kPa (14.70 psia)].
The relationship between oxygen solubility and temperature has been
documented.^' By attributing the difference between the measured or
derived D.O. saturation value, C*mcjs and the textbook value of C* (at the
testing water temperature, Tw) to a'pressure correction, the value of C*0
may be calculated. This procedure involves determining the absolute
pressure (expressed in terms of "equivalent depth") that corresponds to the
difference between C*m(j and textbook C* at temperature T. This pressure
correction is then applied to the textbook C* value at 2Q°C (6S°F) to
determine C*n-
40
-------
The equivalent depth is that increase in pressure that explains the
difference between the measured or derived D.O. saturation value and the
textbook value of C* at temperature T. The following equations show the
relationship of equivalent depth to the other pertinent variables:
/0.01934pa + 0.434zemd - pvpT s
c*^ s( IDo ) c*hT (25)
and:
/C*md\
zemd = 33.871- - 2.30(0.01934pa - PVDT) (26)
\c*hT /
in which:
c*md = measured or derived D.O. saturation value at temperature
T and barometric pressure pa, mg/L
C*nT = handbook D.O. saturation value at temperature T and
pressure 101.3 kPa (14.70 psia) (dry air, 20.9£ 02 by
volume), mg/L
pa = barometric pressure, mm of mercury
zemd = equivalent depth corresponding to the measured or derived
D.O. saturation value, ft
PvpT = vapor pressure of water at temperature T, psig
The factor preceding C*nT in Equation 25 is known as a pressure
correction factor. The numerator of this factor represents the total
pressure of dry air at the equivalent depth in the field. Dividing by 14.70
is necessary since C*hj 1S defined in terms of standard pressure
conditions.
To calculate C*Q, it is assumed that the equivalent depth calculated
at temperature T and barometric pressure Pa is equal to the equivalent
depth at 20°C (68°F) and 101.3 kPa (14.70 psia). Thus, at standard
conditions:
c*0 . (14-70 * °-4^;«" - P^°K20
\ /
in which:
C*h20 = handbook D.O. saturation value at 20°C (68°F) and 101.3
kPa (14.70 psia) (dry air, 20.9% Oj by volume),
-------
Pvp2Q ~ vapor pressure of water at 20°C (6S°F), psig
Upon substitution of the handbook values:
/14.70 + 0.434 zemd - 0.34X
C*0 = ( 19.17
0 \ 14.70 /
which may be reduced to:
C*0 = 8.96 + 0.271 zemd (28)
in which zemc) is calculated using Equation 26.
EVALUATION OF DATA ACCEPTABILITY
From the start of the testing, the need for a method of evaluating the
validity of a test was recognized. At that time and throughout the
testing, the following criterion was used as the basis for clean water test
acceptability. A minimum of five D.O. concentration measurements was
required from each sampling location between truncation limits of 20 and
80% of the D.O. saturation value. Each valid test was required to have all
four sampling locations meet the five D.O. measurements criterion. Data
between 20 and 80% of the saturation were then analyzed by the Equilibrium
Measured technique for each location independently. The four resulting K|_a
values were then required to be within 6% of the average K[_a value. Note
that while the original truncation limits used were 20 to 80% of saturation
for the evaluation of data acceptability, the final analysis presented in
this report used limits of 20 to 90% of saturation.
Included in the analysis of data was the determination of the value of
the correlation coefficient. While this factor did not influence the
staff's judgement of the validity of the run directly, those analyses
showing low correlations were more closely scrutinized. It should also be
noted that it is impossible to determine a correlation coefficient for a
non-linear regression analysis (as used in the Exponential method). A
relative measurement of the goodness-of-fit of the data to the regression
line, however, was determined for the non-linear regression. This number
was determined by summing of the squares of the vertical deviations and
subtracting the total from 1.
PRIMARY DATA ANALYSIS METHOD
The Exponential method was the primary data analysis method used in
this study. Results from this analysis are presented in both tabular and
graphical form; results from the Equilibrium method are presented in
tabular form only. Due to recent work conducted by the ASCE Subcommitte on
Oxygen Transfer Standards,.!/ it is becoming increasingly clear that the
42
-------
Exponential method embodies many desirable features. First, it determines
the best estimates of the parameters C*, K[_a^ and Cj from an analysis of
the data. Second, the form of the equation used allows for the
determination of more precise estimates of the parameters C*, K[_at} and C-j
than are possible with other methods. This is because the curve fitting is
done with the primary variables C and t, which are known more precisely
than secondary variables such as C*-C- Finally, upper end data truncation
is not necessary near the end of the oxygen transfer test.
Disadvantages of the Exponential method are that 1) it requires a
complex non-linear curve fitting procedure, 2} it may sometimes unfairly
weight the data collected near the start of the test, and 3) it does not
account for the effect of gas-side oxygen depletion. These shortcomings,
however, are relatively minor and appear to be more than offset by the
advantages of the method. The complex curve fitting technique is not a
problem if access to computer facilities is available (modern hand-held
programmable calculators are also being investigated for this purpose).!!!'
Because of items 2 and 3 above, use of the Exponential method leads to the
calculation of an apparent (rather than true) K[_at. But as long as the
apparent (rather than true) C* is used to calculate the transfer rate, the
results are nearly the same.
STANDARD OXYGEN TRANSFER CALCULATIONS
The basic oxygen transfer relationship is the product of the overall
volumetric mass transfer coefficient at 20°C (68°F), Kj_a2Q, and the oxygen
deficit, C*-C. In a simplified form, assuming C is 0, this equation
appears as:
(dC/dt)0 = KLa20 C*0 (24)
The standard oxygen transfer rate, SOTR, can be determined by
multiplying (dC/dt)0, the oxygen transfer rate per unit volume at standard
conditions, by the aeration tank volume and the appropriate conversion
factor as shown below:
SOTR = 0.0000624 (dC/dt)0 Vw (29)
in which:
Vw = deflated aeration tank water volume,
To calculate the oxygen transfer efficiency, it is first necessary to
know the oxygen supply rate, OSR. For the purposes of this study, the OSR
is assumed to be constant during the entire test. It is calculated using
the following expression:
43
-------
OSR - Q
dry air
ft 3 wet air
Ib dry air
dry afr
Ib oxygen
Ib dry air
hr
OSR = Q (0.9917) (0. 0752) (Q. 231) (60)
OSR = 1.034 Q
in which:
OSR = oxygen supply rate, Ib
(30)
(24)
Q = airflow at standard conditions of 20°C (68°F), 101.3 kPa
(14.70 psia), and 36% relative humidity, scfm.
Knowing the SOTR and the QSR, the next step is to determine the
standard oxygen transfer efficiency, SOTE. SOTE is the percentage of
oxygen in air that is transferred into the water during aeration of water
at a 0-mg/L D.O. concentration. SOTE is calculated according to the
equation:
SQTE * Mi X 100%
OSR
(31)
in which:
SOTE = standard oxygen transfer efficiency during aeration of
water at 0-mg/L O.O., decimal %.
DETERMINATION OF STANDARD AERATION EFFICIENCY
The aeration efficiency is the pounds of oxygen per hour that are
transferred into the water per unit of power used. The standard aeration
efficiency, N0, is the aeration efficiency at the standard conditions of
20°C (68°F), 101.3 kPa (14.70 psia), and Q-mg/l D.O.
Thus:
N = Standard Oxygen Transfer Rate = SOTR
Power Input P
(32)
Since power can be reported as either delivered, brake, or wire power,
it follows that N0 can be reported as either delivered, brake, or wire
aeration efficiency (Ndo, N^Q, and Nwo, respectively). For a discussion of
delivered, brake, and wire power and the equipment efficiencies used for
the study, refer to the Aerator Power Determinations subsection of
Section 3.
44
-------
SECTION 5
AERATION SYSTEM DESCRIPTIONS
OVERVIEW
The different generic aeration systems tested included fine
bubble dome diffusers, fine bubble tube diffusers, jet aerators, and
various coarse bubble diffusers. Originally, seven manufacturers were
contacted and asked to participate in this evaluation. Near the
conclusion of the program, it was felt that the evaluation of a coarse
bubble sparger system would be beneficial because it is widely used
both nationwide and in LACSD treatment plants. Testing of the
spargers was conducted at the 4.6-m (15-ft) water depth only.
For the original seven system installations, the manufacturer was
responsible for designing the system layout to be tested, providing
drawings for the installation, providing all required materials and
equipment, and inspecting the completed installation.
Testing was conducted at three different nominal power densities
for each of four SWDs. The manufacturers were allowed to change the
configuration of their equipment for each depth, subject to the
constraints of this study. It was required, however, that the
manufacturer use the same configuration for all tests at a given
depth.
FINE BUBBLE DOME DIFFUSERS
The manufacturer of the fine bubble dome diffusion equipment
tested was the Norton Company. At all four depths tested, the
manufacturer chose a single floor coverage system installation. This
design consisted of 126 ceramic dome diffusers mounted on seven 10-cm
(4-in.) diameter PVC headers (Figure 7). Each dome measured 17.8 cm
(7 in.) in diameter and 3.8 cm (1.5 in.) in height (Figure 8). Dry
dome permeability was 7.1 L/sec (15 scfm) at a headloss of 2.5 cm (1
in.) of water. Norton domes were mounted to the header plates with an
orifice bolt. The size of the air control orifice in the bolt was 5.2
mm (13/64 in.). The diffused air release point was at an elevation of
28 cm (11 in.) above the tank floor. Support for this system was
provided by pipe stands attached to the tank floor. All parts of this
manufacturer's system were of non-corroding material.
This manufacturer chose to be tested at the lower power density
range. The nominal power density levels selected were 7.9, 13.2, and
45
-------
I2S MORTON DOME DiFFUSERS
—18 DtFFUSEHS SPACED I1 O.C. = 17' (TYR)—
-i'6"(TYP.)
20" BAFFLES FROM PREVIOUS
"TESTING (TYP. A PLACES)
PLAN
2'6" (TYP.)
20" BAFFLE FROM PREVIOUS
TESTING (TYP 4 PLACES)
•AIR OOWNCOMER
SECTION A-A
11"
Figure 7. Test tank configuration for the Norton dome diffuser
aeration system.
-------
ORIFICE BOLT WITH 13/64^1
CONTROL ORIFICE
CERAMIC DIFFUSER MADE FROM
CRYSTALLINE FUSED ALUMINA
PVC BASE PLATE
4 PVC PIPE
Figure 8. Norton dome diffuser.
-------
26.3 W/m3 (0.3, 0.5, and 1.0 hp/lOQO ft3). Testing air rates ranged
from 35 to 128 I/sec (74 to 272 scfm). This corresponded to airflow
rates per diffuser of 0.3 to 1.0 I/sec (0.6 to 2.2 scfm). Diffuser
headlosses for the systera ranged from 17 cm (6.7 in.) to 49 cm .(19.4
in.) of water.
FINE BUBBLE TUBE DIFFUSERS
The fine bubble tube diffuser system tested was manufactured by
the FMC Corporation. The manufacturer designed a single configuration
for testing of this system at all four depths. A wide-band dual
aeration installation consisting of two headers, each with 21 tube
diffusers was mounted at opposite sides of the tank (Figure 9). The
manufacturer referred to the diffuser tested as the Pearl comb diffuser
(Figure 10). The diffuser media was a white porous modified
acrylonitrile-styrene copolymer material and was available in a number
of porosities. The medium porosity grade, SP-35, was selected for
this study and is the most widely used. These tube diffusers had a
dry tube permeability of 23.7 L/sec (50.3 scfm) at a headloss of 2.54
cm (1 in.) of water. Control orifices for this diffuser were 11.91 mm
(15/32 in.). This installation was supported off the floor with pipe
stands. The diffused air release point was at an elevation of 65 cm
(25 in.) above the tank floor.
The nominal power density levels selected by the manufacturer
were 13.2, 26.3, and 39.5 W/m3 (0.5, 1.0, and 1.5 hp/100 ft3).
Testing air rates ranged from 62 to 197 L/sec (132 to 417 scfm). This
corresponds to airflow rates per diffuser of 1.5 to 4.7 L/sec (3.1 to
9.9 scfm). Diffuser headlosses for the system ranged from 6 cm (2.4
in.) to 31 cm (12.2 in.) of water.
JET AERATORS
The principle of jet aeration is that a primary or motive fluid
(the tank liquid) is directed through a nozzle into a mixing chamber
in the aerator. Air supplied by the blower enters the mixing chamber
and is sheared into minute bubbles when entrained in the motive fluid.
The combined gas-liquid mixture is then jetted into the aeration tank.
This mixture forms a plume that travels horizontally while spreading
through the tank before rising to the surface. It is significant to
note that the air headloss through the jet aerator was usually very
low or negative due to the ejecting action of the motive fluid.
The manufacturer of the jet aeration equipment tested was
Pentech-Houdaille Industries, Inc. The manufacturer chose to test
three different systems in the evaluation. At the 3.0-m (10-ft) SWD,
the manufacturer used a six-nozzle eddy mix jet aeration (EMJA)
cluster connected to a 3.7-kW (5-hp) recirculation pump (Figure 11).
At the 4.6-m (15-ft) SWD, the manufacturer chose to test a 4.9-m
(16-ft) directional mix jet aerator (DMJA) with four nozzles
(Figure 12). Recirculation water was pumped to the DMJA unit by a
48
-------
-20
J
1
1
i
0*
t
r
n i N
K r n " n r
r • | II
i
1 i i
i u u g u L
I ]
j 1-
1
1
i
•i
i r
|
J u
" r n
J_ U U
1 ! iU i
M n n n "
i, y J L
r
i
r
i
-i
i
j
-j L
L
*1 p
HE/
i \
i \
1 i \
J J 1
U3ER NS K
\ BSAMPLiNG STACK MS 1
V_2I FMC SP-35 PEARLCOMB DIFFUSERS PER
HEADER WITH 15/32" CONTROL ORIFICES
i
WALL -"
i
jj
~*=$ SAMPLING
1 STACK N?2
H 4" STEEL D
M /'"PIPE (TYP5 l'3"
i r n ( " n p r
! is'rrYPii \ i]
i J^u \ L J U
j . n r -
-[_ - J L .
f
i
O
TYP).
i
{
i
Ht
• ••
L i
5 DIFFUSERS
p
i
i [
1 !
6'(l
1
i r
1
YP;
1 r
L
I r
•7
j
-|
HEADER
2'9"{TYP1
1 41
1
PLAN
K
p" i
^— AIR DOWNCOMER
W 4" PVC PIPE-m
1C I ! )
H
U
D O O O Q Ql O
K
\
FMC SP-35 PEARLCOMS
.-•DIFFUSERS WITH 15/32"
/ CONTROL ORIFICES
GOO
Q 1 —
*
SECTION A-A
Figure 9. Test tank configuration for the FMC Pearlcomb tube diffuser
aeration system.
49
-------
./r
-NYLON RETAINING ROD
_END CAP MADE
rROM ABS POLYMER
HOLLOW CYLINDRICAL TUBE OF A
MODIFIED ACRYLONITRILE-STYRENE
COPOLYMER (GRADE SP-35)
en
o
TUBE ADAPTER MADE
FROM ABS POLYMER
15/32"
CONTROL
ORIFICE
Figure 10. FMC Pearlcomb diffuser.
-------
PENTECH EMJA CLUSTER
WITH S-1OOJA NOZZLES
B SAMPLING STACK NS 2
PLAN
V
SECTION A-A
Figure 11. Test tank configuration for the Pentech EMJA unit at the 10-ft
water depth.
51
-------
en
4 JET DMJA HEADER WITH
200JA NOZZLES MADE FROM
FIBERGLASS REINFORCED
POLYESTER
6" AIR INLET FLANGE-
LIQUID INLET FLANGE (BEHIND)
Figure 12. Pentech directional mix jet aerator (DMJA).
-------
3.7-kW (5-hp) recirculation pump (Figure 13). At the 6.1-m (20-ft)
and 7.6-m (25-ft) SWDs, the choice was a 10 nozzle EMJA cluster system
(Figure 14). Recirculation water was again supplied to the jets by a
3.7-kW (5-hp) pump (Figure 15). For all depths, the EMJA cluster was
mounted on a skid centered in the tank. Both the EMJA and DMJA units
were fabricated of a fiberglass material. The DMJA unit was
constructed so it could be bolted to the tank floor along one edge of
the tank.
Nominal power testing densities chosen by the manufacturer were
13.2, 26.3, and 39.5 W/m3 (Q.5, 1.0, and 1.5 hp/1000 ft3). This
manufacturer's systems were the only ones tested that utilized power
in addition to that required to supply air. Because the recirculation
pump could only be operated at one speed, the power consumption by the
pump was essentially constant. To vary the nominal power supplied,
the air rates had to be adjusted greatly. Air rates supplied to the
system ranged from 16 to 159 L/sec (33 to 336 scfm). Airflow rates
per jet ranged fro® 2.3 to 36 L/sec (4.9 to 76 scfm). The DMJA jets
discharged air/water at an elevation of 44 cm (17.4 in.) above the
tank floor. The EMJA jets discharged air/water at an elevation of 79
cm (31.1 in.) above the tank floor.
STATIC TUBE AERATORS
The static tube aerators were supplied by Kenics Corporation.
This manufacturer chose to use two different configurations- At the
3.0- and 4.6-ra (10- and 15- ft) SWDs, the manufacturer chose to cover
the floor evenly with nine 30-cm (1-ft) diameter static tube aerator
units, each measuring 0.9-nr (3-ft) high (Figure 16). At the 6.1- and
7.6-m (20- and 25-ft) SWDs, the nine-unit floor coverage was again
chosen; however, this time the static aerators were 1.5 tn (5 ft) high
(Figures 17 and 18). Control orifices for this system consisted of
two drilled holes 15.9 mm (5/3 in.) in diameter located on the bottom
of the air header passing beneath each static tube aerator.
The nominal power density levels selected by the manufacturer
were 13.2, 26.3, and 39.5 W/m3 (0.5, 1.0, and 1.5 hp/1000 ft3).
System air rates ranged from 54 to 190 L/sec (115 to 402 scfm). This
corresponded to airflow rates per aerator of 6 to 21 L/sec (13 to 45
scfm). Aerator headlosses for the system ranged from 4.3 cm (1.7 in.)
to 28 cm (11.2 in.) of water. In this system, air was discharged 11.4
cm (4.5 in.) above the floor.
VARIABLE ORIFICE COARSE BUBBLE OIFFUSERS
The principle of operation of the variable orifice diffuser is
that air passing through hales in the diffuser cause a high frequency
oscillation of a spring that shears the passing air into small
bubbles, thus promoting oxygen transfer. The spring also acts as a
check valve to keep mixed liquor solids out of the air header when the
air is shut off. The headless of the device is due primarily to the
53
-------
20'
CONFIGURATION: SIDE HEADER
PEKTECH 0«JA HEADER
WITH 4-200JA NOZZLES
WALL-
SAMPLING
STACK #2
20'
PLAN
6" PVC PIPE
(AIR)
ENTECH DMJA HEADER
1'5-3/a"
NOTE; PUMP is A SHP
SUBMERSIBLE TYPE
1 SECTION A-A
Figure 13. Test tank configuration for the Pentech DMJA unit at 15-ft
water depth.
54
-------
12 JET EMJA CLUSTER WITH
TEN IOOJA NOZZLES AND
TWO BLANKS MADE FROM—
FIBERGLASS REINFORCED
POLYESTER
BLANKED OFF
NOZZLE
PLAN
6" AIR INLET FLANGE
BLANKED OFF
NOZZLE
12 JET EMJA CLUSTER WITH
•TEN IOOJA NOZZLES AND
TWO BLANKS
-8" RECIRCULAT10N FLOW INLET FLANGE
ELEVATION
Figure 14. Pentech eddy mix jet aerator (EMJA).
55
-------
PENTECH EMJA CLUSTER
WITH lO-iOOJA NOZZLES
B SAMPLING STACK N? 2
PLAN
SECTION A-A
Figure 15. Test tank configuration for the Pentech EMJA unit at the 20-
and 25-ft water depths.
55
-------
20
-20'-
- 9 KENICS 3 ELEMENT STATIC AERATORS
CL
SAMPLING STACK
Q.'
OJ
-4" HOPE PIPE (TYP)
IT--
SAMPLING STACK NS 2
WALL
20" BAFFLES FROM PREVIOUS
TESTING (TYP 4 PLACES)
PLAN
n
-AIR DOWNCCMER
20" BAFFLES FROM PREVIOUS
TESTING (TYP. 4 PLACES!
KENICS 3 ELEMENT STATIC AERATOR (TYP)
AIR RELEASE POINTS
(TYP,)(TWO 5/8" r
"ORIFICES SPACED r
5" APART)
SECTION A-A
4-!
t
Figure 16. Test tank configuration for the Kenics static tube aeration system
at the 10- and 15-ft water depths.
57
-------
5 ELEMENT STATIC AERATOR
MADE FROM HIGH DENSITY
POLYETHYLENE
NOTE- 3 ELEMENT AERATORS
WERE ALSO USED
DURING THE TESTS
4" HIGH DENSITY
POLYETHYLENE PIPE
AIR RELEASE POINTS
(TWO 5/8" ORIFICES-
SPACED 5" APART)
Stt!
STAINLESS STEEL
SUPPORT STAND
Figure 17. Kenics static tube aerator.
58
-------
9 KENICS 5 ELEMENT STATIC AERATORS
SAMPLING STACK N5. I
4" HOPE PIPE (TYR)
SAMPLING STACK N* 2
34 (TYR)-—-•
20 BAFFLES FROM PREVIOUS
TESTING (TYR 4 PLACES)
PLAN
r^
1
* —
3
3
AJF
DO
C !
n h
I 1 I,
INCOMER 20 B/
x—KENJCS 5 ELEMENT STATIC AERATOR (TYR) — —
/
/
1
I
1
a
[
AIR RELEASE POINTS
(TYRMTWO 5/8"
""ORIFICES SPACED
5" APART)
I
—
1
f
iFFLE—
=1
!
6
J
>
p ^L
SECTION A-A
4-1/2"
Figure 18. Test tank configuration for the Kenics static tube aeration system
at the 20- and 25-ft water depths.
59
-------
action of the spring; the Toss through the holes is almost
insignificant by comparison. The spring opening is dependent on the
magnitude of the airflow rate, thus the term "variable orifice." This
also means that the diffuser has a somewhat flat headless-airflow
curve, which can be considered very desirable if a wide range of flow
rates is to be encountered.
The variable orifice diffuser was manufactured by C-E Bauer of
Combustion Engineering, Inc. The variable orifice diffuser was
available in a number of different models. The diffuser was composed
of a stainless steel channel approximately 38 mm (1.5 in.) square and
had a number of thin, flat leaf springs mounted over holes in the
channel. Different models had different numbers of springs per
diffuser. Models with two and three springs per diffuser were tested
in this study, A three-spring model is shown in Figure 19. Springs
were 17 cm (6-3/4 in.) long by 3 cm (1-3/16 in.) wide and, for this
testing, were 0.5 nan (0.02. in.) thick. Each spring was manufactured
to maintain a 227-g (S-oz) spring tension. Each spring covered a
total of four 2.2-cm (7/8-in.) diameter holes through which air
passed. Springs were attached to the channel by means of rivets,
which served as pivot points for the spring.
This manufacturer elected: to use two configurations in the eval-
uation. At the 3.0- and 6.1~m (10- and 20-ft) SWDs, ten Model II
Airpac diffusers were mounted on a central header (Figure 20). At the
SWDs of 4.6 and 7.6 m (15 and 25 ft), eight Model Til Airpac diff users
were mounted on a central header (Figure 21). This system was mounted
across the tank center and supported by wall-mounted hangers.
The testing power densities selected by the manufacturer were
13.2, 26.3, and 39.5 W/m^ (0.5, 1.0, and 1.5 np/1000 ft3). System
aeration rates ranged from 55 to 190 L/sec (118 to 404 scfm).
Corresponding airflow rates per diffuser ranged from 5.7 to 19 L/sec
(12 to 40 scfm). Diffuser headlosses for the system ranged from 27 cm
(10.7 in.) to 59 cm (23.2 in.) of water. The diffuser discharged air
23 cm (9.2 in.) above the tank floor for both configurations.
FIXED ORIFICE COARSE BUBBLE DIFFUSERS - D-24
This fixed orifice coarse bubble diffuser was manufactured by
Sanitaire - Water Pollution Control Corporation. The company referred
to this unit as the Model D-24 stainless steel non-clog diffuser. The
unit was a fixed orifice coarse bubble diffuser and was fabricated of
stainless steel sheet stock. It was somewhat tubular in appearance
and was 61 cm (24 in.) in length (Figure 22). A total of 24 holes
was cut along the length of the tube on the sides; 12 holes were 4.8
mm (3/16 in.) in diameter, and 12 holes were 9.5 mm (3/8 in.) in
diameter. For the most part, the smaller holes were located on a_
horizontal line above that of the larger holes. In addition to the
holes, an open slot 9.5 mm (3/8 in.) wide on both sides of the tube
below the level of the holes was provided. Air was discharged through
60
-------
MODEL in AIRPAC DIFFUSER
WITH 3 LEAF SPRINGS
7/8" ORIFICE - 4 PER
SPRING (TYPICAL)
STAINLESS STEEL TUBING-,
CTl
8 OZ. STAINLESS STEEL
LEAF SPRINGS
NOTE:
THE MODEL II AIRPAC DIFFUSER
WAS ALSO USED DURING THE
TESTS AND HAD 2 LEAF SPRINGS
Figure 19. Bauer Airpac diffuser.
-------
0'
ft
ll_
AA
1
6
J9
-^
i ' 8-3/4" (TYP)-j
I ' "
!
i
|i
DljjlO i ^
SAMPLING it J5 in
STACK N? I H Q ^.V
o-Z~
- | !•;•>
i
1 PIPE—, ' "
'1
^
)
.
UH
—
— ^
- 4" PIPE WALL %
'•
B SAMPLING STACK N? 2
•I
1 '3-1/8" (TYPS-* PLAN
k t.
E
f
K
^
,» AIR DOWP4COMEH
3
r
^
10 BAUER MODEL n AIRPAC
,-DIFFUSERS USING 2-8 Oz.
f SPRINGS ON BOTTOM SIDE
L=f<
-- in
D—L
B 9-5/16"
i
SECTION A-A
Figure 20. Test tank configuration far the Bauer Model II Airpac aeration
system at the 10- and 20-ft water depths.
62
-------
t
-WALL
SAMPLING
STACK N2 |
o
4" PIPE
V
o
d
lo
'w
CO
-------
cr>
STAINLESS STEEL
D-24 DIFFUSER
3/4 NPT THREAD
WITH 3/8"
CONTROL ORIFICE-
Figure 22. Sanitaire D-24 diffuser.
-------
these openings. As low airflow rates increased, air began to
discharge through the larger holes and slots. For the four testing
depths, the manufacturer chose two configurations. At the 3.0- and
6.1-m (10- and ZO-ft) SWDs, a 24 diffuser floor coverage layout was
chosen (Figure 23). At the 4.6- and 7.6-m (15- and 25-ft) SWDs, the
manufacturer chose to test a single, center-mounted, wide-band layout
using 30 diffusers (Figure 24). The system was attached to the steel
tank walls for support. The air discharge point was 16 cm (6.4 in,)
above the floor.
The nominal power densities selected by the manufacturer were
13.2, 26.3, and 39.5 W/m3 (0.5, 1.0, and 1.5 hp/1000 ft3). Airflow
rates ranged from 54 to 190 L/sec (115 to 402 scfm). Corresponding
airflow rates per diffuser were 1.8 to 6.3 L/sec (3.8 to 13.4 scfm).
Each diffuser used a 9.53-mm (3/8-in.) control orifice. Diffuser
headlosses for the system ranged from 3.6 cm (1.4 in.) to 88 cm
(34.6 in.} of water.
FIXED ORIFICE COARSE BUBBLE DIFFUSERS - SUPERFUSER
This system was a fixed orifice coarse bubble diffuser
manufactured by Envirex, Inc. The company name for this diffuser was
the Superfuser. A sketch of the diffuser is shown in Figure 25. Each
diffuser consisted of a plenum chamber made out of molded resin
material with 16 6.4-mm (1/4-in.) diameter holes drilled at two
different elevations in the chamber wall. The bottom of each diffuser
was completely open and was located 17.3 cm (6.8 in.) below the level
of the lowest row of holes in the plenum chamber wall. The diffuser
was open at the bottom to insure that air would always be supplied to
the aeration tank, even in the remote case where the upper holes
became plugged. During normal operation, all the air escaped through
the drilled holes in the plenum chamber; none escaped out of the
bottom of the diffuser. At all four testing depths, this company
chose a single configuration. The installation consisted of a
single-row, center-mounted diffuser configuration (Figure 26). Ten
equally spaced superfusers were mounted on the center header. The
header was supported by floor mounts so as to release air at an
elevation of 32 cm (12.7 in.) above the tank floor. For the
installation tested, no control orifices were used. With the
exception of the floor stands, all parts of this system were
non-metallic.
The nominal power density testing levels chosen by the
manufacturer were 13.2, 26.3, and 39.5 W/m3 (0.5, 1.0, and 1.5 hp/1000
ft3). Air ranges ranged from 56 to 189 L/sec (119 to 400 scfm).
Corrresponding airflow rates per diffuser were from 5.7 to 19 L/sec
(12 to 40 scfm). Diffuser headlosses for the system ranged from 4.1
cm (1.6 in.) to 29 cm (11.5 in.) of water.
65
-------
-20'-
Z'l'
HEADER
r»«
o
•
U3
-6'8*-
(TYP.)
f
-3'4"
8 SAKITA1RE D-24
DIFFUSERS WITH 3/l!
CONTROL ORIFICES
PER HEADER (HP.!
HEADER
4" STAINLESS STEEL
HEADER (TYP.)^
6" STAINLESS STEEL
HEADER
_ SAMPLING
STACK #2
i
20'
»
t
PLAN
-v
AiR DOVNCOMER
CONFIGURATION: TOTAL FUJOR COVERAGE
SECTION A-A t
Figure 23. Test tank configuration for the Sarritatre D-24 aeration system at
the 10- and ZQ-ft water depths.
66
-------
20'-
fl
II
f
-•"""s
IJ^»
J"
SAMPLJMS *
'•E* „ « j o" . ^'fr_* v--*1 —
r==
i r
t i — »
STACK »*>! £
B * |__:_.:.
w
HEADER g t""" '" '"' *•
HM «
M
!!
jj
% c 1
L
ta
3 i^___^
£ 1
j
i -Z=H
* —'30 SftNITAiBE 0-24
„- OIFFUSEBS WITH
X 3/8" CONTROL
ten..; :•"•-) ORIFICES
Me===a
HEADER
^"~r *»Z
^ ,
4* STAINLESS STEEL
rf^-""~ HEADER (TYPJ
«_____!
6" S1WNUCSS
k=— • : .1^,^' STEEL MAIN
^ (TYR)
i
j
HEADER
***3
-x
r
".)) IN
E
I
Ls
"^
j
j
j
*
i
R
1
|
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SAMPLING
-i—:1"""":;,:,. :~3
" k
— j_
20'
i
!
f
,
t.
i
j
,
PLAN
I
¥
COJ^iQURATiON: WIDE BAND -CENTRAL HEADER
3
P3 6-5/ I ff1-
h
E
M SAN1TAKE 0-24 i
y'"'" DIFFUSER
1 _J ~1 _ — J
4
i
i
SECTION A-A
Figure 24. Test tank configuration for the Sanitaire 0-24 aeration system at
the 15- and 25-ft water depths.
67
-------
DISCHARGE
HOLES
SUPERFUSER DIFFUSER
MADE FROM MOLDED RES IN
1-3/8*
Figure 25. Envirex Superfuser diffyser.
68
-------
10'-
•zo'
I'B"-
SAMPL1MG
STACK #1
B
10 ENV1REX SUPERFUSER
DIFFUSERS *ITHOUT
CONTROL ORIFICES
CONFIGURATION:
CENTRAL HEADER
20'
PLAN
AIR QOKNCOMER
EJIVIREX SUPERFUSER 01FFUSER
r 10-l/lff'
SECTION A-A f
Figure 26. Test tank configuration for the Envfrex Superfuser aeration
system.
69
-------
FIXED ORIFICE COARSE 3UBBU DIFFUSERS - DEFLECTOFUSER
Near the conclusion of this study, it was decided that the
inclusion of a common coarse bubble diffuser would be worthwhile. The
Deflectofuser was chosen because this simple sparger-type diffuser is
commonly used throughout the industry and in LACSD facilities.
In a separate LACSD study, the sparger was tested in both dual
aeration and single-side aeration configurations. This comparison
study also investigated the use of wide-band width configurations
using 20 diffusers in one case- and 40 diffusers in the other case.
The configuration yielding the best results, dual aeration using 40
diffusers, was tested in this study.
The Deflectofuser is a fixed orifice coarse bubble diffuser
manufactured by the FMC Corporation (Figure 27). The installation
consisted of 40 Deflectofusers, with 20 mounted on each header (Figure
28). It should be noted that this configuration was designed by the
LACSD engineering staff and not the equipment manufacturer. The unit
was made of acrylonitrile butadiene styrene (ABS) plastic. It
measured 7.6 cm (3 in.) in diameter and 5.6 cm (2-3/16 in.) in height.
Air was discharged through a discharge ring of four jets 9.5 mm (3/8
in.) in diameter at right angles to the adjacent openings. Each
diffuser had an 8.7-cra (11/32-in.) orifice and was directly mounted to
a 19.0-mm (3/4-in.) NPT 90a pipe elbow. Diffusers were mounted on
both sides of the header using pipe nipples of 25-cm (10-in.) and
51-cm (20-in.) lengths alternately. The air release point of this
•system was at an elevation of 69 on (27.1 in.) above the tank floor.
This installation was supported by floor stands.
The system was tested at only the 4.6-m (15-ft) SWO at nominal
power densities of 13.2, 26.3, and 39.5 W/m3 (0.5, 1.0, and 1.5
hp/1000 ft3). Air rates for this installation ranged from 63 to 188
L/sec (134 to 398 scfm). Corresponding airflow rates per diffuser
were 1.6 to 4.7 L/sec (3.4 to 10 scfm). Diffuser headlosses for the
system ranged from 8.1 cm (3.2 in.) to 52 cm (20.4 in.) of water.
70
-------
DEFLECTOFUSER DIFFUSER
MADE FROM ABS PLASTIC
3/4" NPT
THREAD
11/32" CONTROL ORIFICE
3/8" DIAMETER
DISCHARGE HOLES (4 TYPICAL)
Figure 27. FMC Deflectofuser diffuser.
71
-------
fi^T
T I \
,4 II I II i 1 1
10"
(TYP)
SAMPLING
STACK M° 1
20 FMC DEFLECTOFUSER
- OIFFUSERS PER HEADER
WITH 1 1/32" CONTROL ORIFICES
WALL
t
4" STEEL PIPE
STACK N*
CTYP)
^ 9 DIFFUSERS_
f f f
HEADER MS
1 f
20'
11
PLAN
-V
DOWNCOMER
T t T ? r t t f T t t r-y- t t t t t[
T
2*3-1/16"
i
SECTION A-A
Figure 28. Test tank configuration for the FMC Oeflectofuser (Sparger)
aeration system at the 15-ft water depth.
72
-------
SECTION 6
TEST RESULTS
OVERVIEW
Before proceeding with a discussion of test results, it is important
to realize the limitations of clean water test data. Clean water data
alone cannot be used to predict oxygen transfer performance in mixed
liquor. To relate clean water oxygen transfer results to anticipated
aerator performance in mixed liquor, two correction factors are required.
The first factor, alpha (<*), is the oxygen transfer coefficient correction
factor. The second factor, beta (&), is the oxygen saturation correction
factor. These correction factors are applied to the basic aeration
equation as follows:
dC/dt = <*KLa (eC* - C) (33)
Only with accurate alpha and beta factors, used in conjunction with
clean water data, can successful prediction of oxygen transfer performance
in activated sludge be achieved. It is important to stress that alpha
factors, the ratio of wastewater Kj_a to clean water K[_a, vary widely as a
function of the type of aeration device, wastewater characteristics and
degree of prior treatment, aeration system configuration, aeration tank
geometry, and other considerations. For the type of equipment tested
during this study, alpha factors from 0.35 to 0.95 have been reported.
This variation is significant and could cause the relative performance of
the oxygen transfer devices in mixed liquor to be completely different than
as indicated in clean water.
The results obtained in this clean water study are accurate. It
should be stressed, however, that the data were obtained under very
specific conditions of test medium, tank geometry, and diffuser
configuration, utilizing specific test procedures and data analysis
techniques. The results could have been much different under different
conditions, not only from an absolute standpoint, but in terms of the
comparison between the various generic oxygen transfer devices. Changing
conditions, such as the test medium or tank geometry, could affect the
performance of one generic device to a greater extent than that of another.
Equipment efficiency may be affected by testing liquid
characteristics; consequently, it is common to specify a manufacturer's
compliance using clean water tests. Because a clean water test is
repeatable, it may be used to demonstrate general trends in aeration
73
-------
performance with regard to airflow rates, diffuser location, tank geometry,
and other parameters. When the aerator's alpha and beta factors are known
for a particular wastewater, clean water tests also provide meaningful data
for activated sludge aeration system design. Even then, the flow regime
used will have a significant effect on alpha. For example, alpha will tend
to approach a constant value throughout a completely mixed aeration tank,
whereas it will increase from inlet to outlet of a plug flow tank as the
influent wastewater becomes progressively more treated.
TABULAR PRESENTATIONS
Presentation of Analysis Resultsfor the Exponentialand Equi1ibrium Methods
Tables 3 through 18 contain the results produced by the eight aeration
systems tested in this study. For each system, two tables of results are
presented. The tables contain the results of analysis by both the
Exponential and the Equilibrium methods of analysis. While the primary
analysis method is the Exponential method, results of analysis by the
second method are supplied for comparison purposes. Every table is
generally composed of the same columns; an extra column is supplied for the
jet aeration system results. In the first five or six columns, information
is supplied that identifies and characterizes the tests. These columns are
Date, Run, Water Depth, Delivered Power Density, and Airflow Rate. For the
jet aeration system, the Delivered Pump-Air Power Split is also indicated.
The column identified as "Date" refers to the date on which a test was
conducted. "Run" differentiates between tests taking place on the same
day. Run Nos. 1, 2, 3, and 4 were conducted in that order. "Water Depth"
is the measured aeration tank water depth during aerator testing (inflated
condition). "Delivered Power Density", "Airflow Rate", and "Delivered
Pump-Air Power Split" are as described earlier in this report. The last
five columns summarize results of analysis. These columns are Ki_a2Q» C*0,
Standard Oxygen Transfer Efficiency, and Standard Delivered and Standard
Wire Aeration Efficiencies. Data presented in the tables are expressed in
U.S. customary units. Factors for the conversion of U.S. customary units
to SI units are supplied in the front of this report.
Comparison of Analysis^Results for the. Exponential and Equilibrium Methods
As indicated above, data obtained in this study were evaluated by the
Equilibrium and the Exponential methods of analysis, although the primary
analysis method chosen was the Exponential method. Review of the results
showed that the difference between results obtained by the two analysis
methods is small.
To evaluate the agreement of the results obtained using the two
analysis methods, the following procedure was used. For each test, the
result obtained by the Exponential method was divided by the result
obtained by the Equilibrium method. These ratios were then analyzed to
obtain the mean ratio and standard deviation. Data that were compared in
74
-------
TABLE 3. SUMMARY OF EXPONENTIAL METHOD RESULTS: NORTON FINE BUBBLE DOME DIFFUSERS
Date Run
03/24/78 1
04/21/78 1
04/24/78 1
04/25/78 1
04/26/78 1
04/27/78 1
05/04/78 1
05/05/78 1
05/08/78 1
05/09/78 1
05/10/78 1
05/15/78 1
05/16/78 1
Delivered l
Water Power
Depth Density
(ft) (hp/1000 ft3)
25
10
10
15
15
15
20
20
25
25
20
10
20
1. The delivered horsepower
conditions of 20°C, 14.70
pressures
2 . Based on
3. The wire
were determined
the Exponential
horsepower used
0.28
0.57
0.32
0.31
0.54
1.24
0.51
1.15
1.16
0.50
0.30
1.37
0.30
Air-
flow
Rate KLa20 2
(scfm) (1/hr)
73.8 5.34
125.8 11.31
73.9 7.17
74.5 6.41
126.0 9.87
253.4 17.66
126.9 9.47
256.1 16.39
272.4 14.61
127.5 8.54
76.3 6.07
248.3 19.30
75.0 5.82
numbers are based on the adiabatic
psia, and 36%
in accordance
model analysis
Standard
Oxygen
Transfer
C*0 Efficiency
(tng/L) («)
11.42
9.81
9.88
10.24
10.45
10.60
11.12
11.02
11.67
11.65
11.33
10.17
11.44
compression
relative humidity have been used
with Equations 4 and
using Winkler data.
6.
in this analysis is related to delivered horsep
49.48
21.30
23.20
32.03
29.71
26.61
39.81
33.80
37.16
46.69
43.55
19.14
42.85
equation.
. Blower
ower by a
Standard
Aeration Efficiency
(Ib 02/hp-hr)
Delivered
13.44
12.10
13.95
13.37
11.98
9.33
12.72
9.68
9.11
12.46
14.17
8.94
13.96
Standard ambient
inlet and discharge
Wire
8.22
7.40
8.53
8.18
7.33
5.71
7.78
5.92
5.57
7.62
8.66
5.47
8.54
blower efficiency of
0.70, a coupling efficiency of 0.95, and a motor efficiency of 0.92 (an overall or combined efficiency of
0.612).
-------
TABLE 4. SUMMARY OF EQUILIBRIUM METHOD RESULTS: NORTON FINE BUBBLE DOME DIFFUSERS
01
Delivered
Water Power
Depth Density
T
Date
03/24/78
04/21/78
04/24/78
04/25/78
04/26/78
04/27/78
05/04/78
05/05/78
05/08/78
05/09/78
05/10/78
05/15/78
05/16/78
1. The
Run (ft) (hp/1000 ft^)
1
1
1
1
1
1
1
1
1
1
1
1
1
delivered
conditions of
25
10
10
15
15
15
20
20
25
25
20
10
20
0.28
0.57
0.32
0.31
0.54
1.24
0.51
1.15
1.16
0.50
0.30
1.37
0.30
Air-
flow
Rate
(acfm)
73.8
125.8
73.9
74.5
126.0
253.4
126.9
256.1
272.4
127.5
76.3
248.3
75.0
horsepower numbers are based on the
20°C, 14.70
pressures were determined
psia, and 36%
in accordance
2. Based on the Equilibrium model analysis
3. The
wire horse
jpower used
relative
KLa20 2
Standard
Oxygen
Transfer
C*0 Efficiency
(1/hr) (mg/L)
5
11
7
6
9
17
9
16
14
8
6
19
5
.36
.64
.18
.22
.92
.95
.57
.33
.72
.42
.21
.93
.85
11.42
9.72
9.88
10.36
10.40
10.53
11.08
10.97
11.66
11.73
11.25
10.07
11.40
adiabatic compression
humidity have
with Equations
using Winkler
4 and 6
data.
(SO
49.60
21.72
23.21
31.40
29.70
26.87
40.10
33.94
37.42
46.36
44.27
19.58
42.88
equation.
been used. Blower
*
in this analysis is related to delivered horsepower by a
Standard 3
Aeration Efficiency
(Ib 02/hp-hr)
Delivered
13
12
13
13
11
9
12
9
9
12
.47
.34
.96
.10
.98
.42
.81
.71
.18
.37
14.40
9
13
Standard
inlet and
.15
.97
ambient
Wire
8.24
7.55
8.54
8.01
7.33
5.76
7.83
5.94
5.61
7.57
8.81
5.59
8.54
discharge
blower efficiency
of
0.70, a coupling efficiency of 0.95, and a motor efficiency of 0.92 (an overall or combined efficiency of
0.612).
-------
TABLE 5. SUMMARY OF EXPONENTIAL METHOD RESULTS: FMC FINE BUBBLE TUBE DIFFUSERS
Date Run
08/29/78
08/29/78
08/29/78
08/30/78
08/30/78
08/30/78
09/29/78
02/08/79
02/08/79
02/08/79
02/09/79
02/09/79
02/09/79
1
2
3
1
2
3
1
1
2
3
1
2
3
1. The delivered
conditions of
pressures
2 . Based on
3. The wire
were
the
Water
Depth
Delivered *
Power
Density
it
(ft) (hp/1000 ft')
10
10
10
25
25
25
10
15
15
15
20
20
20
2.
1.
0.
1.
1.
0.
1.
1.
1.
0.
1.
1.
0.
02
16
54
66
07
51
19
81
05
51
74
08
49
Air-
flow
Rate
(scfm)
412.2
276.6
142.1
414.5
281.1
139.0
277.6
408.6
264.4
136.0
417.4
277.5
131.8
horsepower numbers are based on the
20°C, 14.70
determined
Exponential
horsepower used
psia,
and 36%
in accordance
model
analysis
relative
f\
KLa20 '
(1/hr)
17.46
13.37
7.63
14.99
11.12
6.39
13.39
16.61
11.90
6.88
16.73
11.62
6.10
C*o
(mg/L)
9.B7
9.99
10.05
11.23
11.26
11.54
9.98
10.50
10.54
10.63
10.80
11.05
11.19
adiabatic compression
humidity have
been used
Standard
Oxygen
Transfer
Efficiency
(*)
10.06
11.68
12.95
23.93
24.40
31.71
11.61
15.34
17.07
19.87
20.69
22.17
25.04
equation.
Blower
Standard 3
Aeration Efficiency
(Ib 02/hp-hr)
Delivered
5.
7.
a.
6.
7.
8.
6.
5.
7.
9.
6.
7.
8.
Standard
inlet and
29
14
86
23
25
99
99
94
36
12
39
37
69
ambient
discharge
Wire
3.23
4.37
5.42
3.81
4.44
5.50
4.27
3.63
4.51
5.58
3.91
4.51
5.31
with Equations 4 and 6.
using Winkler data.
in this analysis is related to delivered horsepower by a
blower efficiency of 0.
a coupling efficiency of 0.95, and a a motor efficiency of 0.92 (an overall or combined efficiency of 0.612).
-------
TABLE 6. SUMMARY OF EQUILIBRIUM METHOD RESULTS: FMC FINE BUBBLE TUBE DIFFUSERS
00
Delivered 1
Water Power
Depth Density
Date
08/29/78
08/29/78
08/29/78
08/30/78
08/30/78
08/30/78
09/29/78
02/08/79
02/08/79
02/08/79
02/09/79
02/09/79
02/09/79
1. The
Run (ft) (hp/1000 ft>)
1
2
3
1
2
3
1
1
2
3
1
2
3
10
10
10
25
25
25
10
15
15
15
20
20
20
delivered horsepower
conditions of 20°C, 14.70
pressures
2. Based on
3. The
wire
were determined
the Equilibrium
horsepower used
2.02
1.16
0.54
1.66
1.07
0.51
1.19
1.81
1.05
0.51
1.74
1.08
0.49
Air-
flow
Rate
KLa20 2
(scfm) (1/hr)
412.
276.
142.
414.
281.
139.
277.
408.
264.
136.
417.
277.
131.
numbers are based on
psia, and 36%
in accordance
model analysis
2 17
6 13
1 8
5 15
1 11
0 6
6 13
6 16
4 12
0 7
4 16
5 11
8 6
.19
.02
.05
.49
.26
.53
.38
.78
.10
.01
.86
.87
.35
the adiabatic
Standard
Oxygen
Transfer
C*Q Efficiency
(mg/L)
9.96
9.96
9.86
11.10
11.21
11.47
9.95
10.47
10.49
10.56
10.81
10.90
11.00
compression
relative humidity have been used
with
using
in this analysis is
Equations
Winkler
4 and
data.
6.
(X)
10.00
11.34
13.41
24.44
26.62
32.16
11.57
15.44
17.28
20.09
20.87
22.32
25.64
equation.
. Blower
related to delivered horsepower by a
Standard 3
Aerstion Efficiency
(Ib 02/hp-hr)
Delivered Wire
5.
6.
9.
6.
7.
9.
6.
5.
7.
9.
6.
7.
8.
Standard
inlet and
26
93
18
36
30
12
96
98
45
22
45
42
89
ambient
discharge
3.21
4.24
5.61
3.89
4.47
5.58
4.26
3.66
4.56
5.64
3.94
4.54
5.44
blower efficiency of 0.
a coupling efficiency of 0.95, and a motor efficiency of 0.92 (an overall or combined efficiency of 0.612).
-------
TABLE 7. SUMMARY OF EXPONENTIAL METHOD RESULTS: PENTECH JET AERATORS
Delivered Air- Delivered
Water Power flow Pump/Air
Depth Denaity Rate Power Split KLa2Q 2
Date Run (ft) (hp/JOOO ft2) (scfm) (%/%) (1/hr)
07/05/78 1 25 1.56 336.2 82.2/17.8 12.23
07/07/78 1 20 1.62 322.4 78.7/21.3 12.83
07/07/78 2 20 0.96 170.8 64.4/35.6 7.95
07/07/78 3 20 0.51 52.9 33.9/66.1 3.24
07/08/78 1 25 0.48 64.3 44.2/55.8 3.46
07/08/78 2 25 1.01 202.1 72.4/27.6 8.82
07/10/78 2 10 1.89 329.3 77.8/22.2 10.98
07/10/78 3 10 0.50 32.7 18.6/81.4 2.52
07/12/78 1 15 1.64 302.9 81.2/18.8 12.26
07/19/78 1 15 1.03 180.2 69.9/30.1 7.56
07/20/78 1 15 0.51 54.6 39.1/60.9 3.23
07/27/78 1 15 1.63 300.4 80.7/19.3 12.05
07/28/78 1 15 1.02 176.7 69.3/30.7 7.84
08/01/78 1 10 1.17 203.4 64.4/35.6 7.76
08/01/78 2 10 0.59 54.5 29.3/70.7 3.16
08/09/78 1 25 0.49 65.2 44.3/55.7 3.14
08/14/78 1 25 0.49 65.6 44.5/55.5 3.28
08/16/78 1 20 0.50 49.3 32.0/68.0 2.89
Oxygen Standard '
Transfer Aeration Efficiency
C*0 Efficiency (Ib 02/hp-hr)
(mq/L)
11.29
10.99
11.10
11.22
11.97
11.41
9.68
10.35
10.34
10.68
11.11
10.42
10.61
9.76
10.07
11.94
11.96
11.41
1. The delivered horsepower numbers are based on the adiabatic compression
conditions of 20°C, 14.70 psia, and 36* relative humidity have been used
pressures were determined in accordance with Equations 4 and 6.
2. Based on the Exponential model analysia using Winkler data.
3. The wire horsepower used in this analysis is related to delivered
(*)
23.85
20.83
24.98
32.85
37.79
29.44
7.84
18.24
15.26
16.12
23.80
15.01
17.12
9.10
14.19
34.35
35.49
31.73
equation.
. Blower
horsepower by a
Delivered Wire
5.36 3.36
5.34 3.36
5.72 3.67
4.41 2.95
5.22 3.44
6.19 3.92
3.53 2.23
3.04 2.09
4.78 3.00
4.86 3.09
4.40 2.93
4.74 2.97
5.13 3.27
4.08 2.62
3.41 2.30
4.78 3.15
4.95 3.26
4.08 2.74
Standard ambient
inlet and discharge
blower efficiency of
0.70, a coupling efficiency of 0.95, and a motor efficiency of 0.92 (an overall or combined efficiency
of 0.612).
-------
TABLE 8. SUMMARY OF EQUILIBRIUM METHOD RESULTS: PENTECH JET AERATORS
do
O
Date Run
07/05/78 1
07/07/78 1
07/07/78 2
07/07/78 3
07/08/78 1
07/08/78 2
07/10/78 2
07/10/78 3
07/12/78 1
07/19/78 1
07/20/78 1
07/27/78 1
07/28/78 1
08/01/78 1
08/01/78 2
08/09/78 1
08/14/78 1
08/16/78 1
Delivered * Air- Delivered
Water Power flow Pump/Air
Depth Density Rate Power Split KLa2Q 2
(ft) (hp/1000 ft!) (scfm) (%/%) (1/hr)
25 1.56 336.2 82.2/17.8 12.09
20 1.62 322.4 78.7/21.3 12.62
20 0.96 170.8 64.4/35.6 7.89
20 0.51 52.9 33.9/66.1 3.12
25 0.48 64.3 44.2/55.8 3.29
25 1.01 202.1 72.4/27.6 8.72
10 1.89 329.3 77.8/22.2 11.29
10 0.50 32.7 IB. 6/81. 4 2.21
15 1.64 302.9 81.2/18.8 12.21
15 1.03 180.2 69.9/30.1 7.45
15 0.51 54.6 39.1/60.9 3.20
15 1.63 300.4 80.7/19.3 12.16
15 1.02 176.7 69.3/30.7 7.95
10 1.17 203.4 64.4/35.6 7.91
10 0.59 54.5 29.3/70,7 3.13
25 0.49 65.2 44.3/55.7 3.13
25 0.49 65.6 44.5/55.5 3.23
20 0.50 49.3 32.0/68.0 2.74
c*o
(mq/L)
11.16
10.90
11.11
11.07
11.72
11.37
9.73
9.74
10.33
10.61
11.08
10.40
10.67
9.86
10. 08
11.93
11.87
11.20
1. The delivered horsepower numbers are based on the adiabatic compression
conditions
pressures
of 20°C, 14.70 psia, and 36S relative humidity have
were determined in accordance with Equations 4 and 6
been used
Oxygen Standard '
Transfer Aeration Efficiency
Efficiency (Ib 02/hp-hr)
(SO
23.85
20.67
24.80
32.14
36.62
29.22
8.02
16.96
15.22
16.00
23.63
15.18
17.27
9.19
14.08
34.28
35.19
30.67
equation.
. Blower
Delivered Wire
5.36
5.30
5.68
4.32
5.05
6.14
3.61
2.83
4.77
4.82
4.37
4.79
5.17
4.12
3.38
4.77
4.91
3.94
Standard ambient
3.36
3.33
3.64
2.09
3.33
3.90
2.28
1.94
2.99
3.07
2.91
3.01
3.30
2.64
2.28
3.14
3.24
2.64
inlet and discharge
2. Based on the Equilibrium model analysis using Winkler data.
3. The wire h
orsepower used in this analysis is related to delivered horsep
ower by a
blower efficiency
of
0.70, a coupling efficiency of 0.95, and a motor efficiency of 0.92 (an overall or combined efficiency
of 0.612).
-------
TABLE 9. SUMMARY OF EXPONENTIAL METHOD RESULTS: KENICS STATIC TUBE AERATORS
CD
Delivered *•
Water Power
Depth
Date
05/25/78
05/26/78
06/02/78
06/08/78
06/13/78
06/13/78
06/14/78
06/14/78
06/22/78
06/23/78
06/26/78
06/28/78
1. The
Run
1
1
1
1
1
2
2
3
1
1
1
1
delivered
conditions of
pressures were
Density
(ft) (hp/1000 ftj)
20
20
25
15
15
15
10
10
25
25
20
10
horsepower
20°C, 14.70
0.49
1.02
1.05
0.48
1.74
1.08
1.11
0.50
1.60
0.48
1.70
1.90
Air-
flow
Rate
(scfm)
122.6
245.0
262.3
115.4
356.7
243.5
230.6
115.5
381.0
125.8
377.5
345.6
numbers are based on the
paia, and 36%
determined in accordance
2. Based on the Exponential
3. The
wire horse
power used
model analysis
in this analysJ
relative
Standard
Oxygen
Transfer
KLa20 2
(1/hr)
3.53
6.62
8.09
3.16
11.05
7.74
6.59
3.43
10.99
3.58
10.76
9.32
adisbatic
Standard *
Aeration Efficiency
C*0 Efficiency
(mg/L)
10.88
10.71
10.63
9.98
9.56
9.42
9.50
9.24
10.80
11.23
10.41
9.87
compression
humidity have been used
with Equations 4 and
6.
(S)
15.13
13.95
19.68
10.39
11.13
11.43
6.41
7.04
18.47
19.10
14.28
6.47
equation.
Blower
(lb
02/hp-hr)
Delivered Wire
4
4
5
4
3
4
3
4
4
5
4
3
.88
.32
.13
.29
.92
.40
.69
.14
.59
.18
.08
.01
Standard
inlet
and
2
2
3
2
2
2
2
2
2
3
2
1
ambient
discharge
.99
.64
.14
.62
.40
.69
.26
.53
.81
.17
.50
.84
using Winkler dsta.
La is related to delivered horsep
ower by a
blower
efl
Ficiency of
0.70, a coupling efficiency of 0.95, and a motor efficiency of 0.92 (an overall or combined efficiency of
0.612).
-------
TABLE 10. SUMMARY OF EQUILIBRIUM METHOD RESULTS: KENICS STATIC TUBE AERATORS
Date
05/25/78
05/26/78
06/02/78
06/08/78
06/13/78
06/13/78
06/14/78
°° 06/14/78
06/22/78
06/23/78
06/26/78
06/28/78
Run
1
1
1
1
1
2
2
3
1
1
1
1
Water
Depth
(ft)
20
20
25
15
15
15
10
10
25
25
20
10
Delivered 1
Power
Density
Air-
flow
Rate
(hp/1000 ft3) (scfm)
0.49
1.02
1.05
0.48
1.74
1.08
1.11
0.50
1.60
0.48
1.70
1.90
122.6
245.0
262.3
115.4
356.7
243.5
230.6
115.5
381.0
125.8
377.5
345.6
KLa20 2
(1/hr)
3.47
6.73
8.09
3.21
10.76
7.33
6.53
3.40
10.99
3.62
10.63
9.55
c*0
(mg/L)
10.91
10.59
10.75
10.34
9.96
10.11
10.00
9.72
10.82
11.21
10.34
9.78
Standard
Oxygen
Transfer
Efficiency
(*)
14.89
14.02
19.75
10.49
10.86
11.06
6.88
6.97
18.50
19.26
14.01
6.57
Standard 3
Aeration Efficiency
(Ib 02/hp-hr)
Delivered
4.80
4.34
5.15
4.33
3.83
4.26
3,67
4.10
4.60
5.22
4.01
3.06
Wire
2.94
2.65
3.15
2.65
2.34
2.61
2.25
2.51
2.82
3.19
2.45
1.87
1. The delivered horsepower numbers are based on the adiabatic compression equation. Standard ambient
conditions of 20°C, 14.70 psia, and 36% relative humidity have been used. Blower inlet and discharge
pressures were determined in accordance with Equations 4 and 6.
2. Based on the Equilibrium model analysis using Winkler data.
3. The wire horsepower used in this analysis ia related to delivered horsepower by a blower efficiency of
0.70, a coupling efficiency of 0.95, and a motor efficiency of 0.92 (an overall or combined efficiency of
0.612).
-------
TABLE 11. SUMMARY OF EXPONENTIAL METHOD RESULTS: BAUER VARIABLE ORIFICE DIFFUSERS
Date
12/05/78
12/05/78
12/05/78
12/06/78
12/06/78
12/06/78
12/07/78
Co 12/07/78
°° 12/07/78
12/08/78
12/08/78
12/08/78
12/15/78
12/15/78
Run
1
2
3
1
2
3
1
2
3
1
2
3
1
2
Water
Depth
(ft)
20
20
20
10
10
10
15
15
15
25
25
25
10
10
Delivered *
Power
Density
(hp/1000 ft3)
1.75
1.10
0.53
0.53
1.18
2.14
1.82
1.18
0.53
0.52
1.07
1.74
2.05
0.54
Air-
flow
Rate
(scfm)
380.7
254.9
130.0
118.9
234.8
369.6
363.2
253.2
121.7
132.1
260.4
403.9
362.9
117.6
KLa20 2
(1/hr)
12.51
7.63
3.54
3.33
7.04
11.76
11.32
7.51
3.27
3.51
7.47
12.51
10.76
3.32
c*o
(mg/L)
10.32
10.47
10.58
9.69
9.50
9.48
10.04
10.09
10.14
11.07
11.12
10.79
9.53
9.46
Standard
Oxygen
Tranafer
Efficiency
(SO
16.28
15.14
13.93
6.59
6.91
7.31
11.40
10.83
9.85
17.52
18.93
19.63
6.93
6.54
Standard 3
Aeration Efficiency
(Ib 02/hp-hr)
Delivered
4.57
4.53
4.37
3.79
3.53
3.26
3.89
4.00
3.91
4.67
4.84
4.78
3.11
3.67
Wire
2.80
2.77
2.67
2.32
2.16
1.99
2.38
2.45
2.39
2.86
2.96
2.92
1.90
2.25
1. The delivered horsepower numbers are based on the adiabatic compression equation. Standard ambient
conditions of 20°C, 14.70 psia, and 36% relative humidity have been uaed. Blower inlet and discharge
pressures were determined in accordance with Equations 4 and 6.
2. Based on the Exponential model analysis using Winkler data.
3. The wire horsepower used in this analysis is related to delivered horsepower by a blower efficiency of 0.70,
a coupling efficiency of 0.95, and a motor efficiency of 0.92 (an overall or combined efficiency of 0.612).
-------
TABLE 12. SUMMARY OF EQUILIBRIUM METHOD RESULTS: BAUER VARIABLE ORIFICE DIFFUSERS
Delivered *
Water Power
Depth Density
Date Run
12/05/78 1
12/05/78 2
12/05/78 3
12/06/78 1
12/06/78 2
12/06/78 3
12/07/78 1
12/07/78 2
12/07/78 3
12/08/78 1
12/08/78 2
12/08/78 3
12/15/78 1
12/15/78 2
1. The delivered
conditions of
(ft) (hp/1000 ft->)
20
20
20
10
10
10
15
15
15
25
25
25
10
10
horsepower
20°C, 14.70
pressures were determined
2. Based on the
Equilibrium
3. The wire horsepower used
1.75
1.10
0.53
0.53
1.18
2.14
1.82
1.18
0.53
0.52
1.07
1.74
2.05
0.54
Air-
flow
Rate ^La20
(acfm) (1/hr)
380.7 12.46
254.9 7.82
130.0 3.57
118.9 3.49
234.8 7.12
369.6 11.83
363.2 11.57
253.2 7.61
121.7 3.32
132.1 3.67
260.4 8.06
403.9 12.81
362.9 10.71
117.6 3.25
Standard
Oxygen
Tranafer
C*0 Efficiency
(mg/L)
10.33
10.40
10.52
9.55
9.46
9.48
10.02
10.04
10.09
10.85
10.84
10.66
9.56
9.50
numbers are baaed on the adiabatic compression
paia, and 36%
in accordance
model analysis
relative humidity have
with Equations 4 and 6
using Winkler data.
(55)
16.22
15.40
13.98
6.81
6.95
7.35
11.62
10.93
9.98
17.98
19.92
19.87
6.92
6.44
equation.
been used. Blower
«
in this analysis is related to delivered horaef
lower by a
Standard '
Aeration Efficiency
(Ib 02/hp-hr)
Delivered
4.56
4.60
4.38
3.92
3.55
3.28
3.96
4.04
3.96
4.79
5.09
4.83
3.11
3.62
Standard ambient
inlet and discharge
Wire
2.79
2.82
2.68
2.40
2.17
2.01
2.42
2.47
2.42
2.93
3.11
2.96
1.90
2.21
blower efficiency of
0.70, a coupling efficiency of 0,95, and a motor efficiency of 0.92 (an overall or combined efficiency of
0.612).
-------
TABLE 13. SUMMARY OF EXPONENTIAL METHOD RESULTS: SANITAIRE COARSE BUBBLE DIFFUSERS
Delivered *•
Water Power
Depth Density
Date
11/06/78
11/06/78
11/06/78
11/07/78
11/07/78
11/07/78
11/09/78
11/09/78
11/09/78
11/15/78
11/15/78
11/15/78
1. The
Run
1
2
3
1
2
3
1
2
3
1
2
3
delivered
conditions of
(ft) (hp/1000 ftj)
20
20
20
10
10
10
15
15
15
25
25
25
horsepower
20°C, 14.70
pressures were determined
2. Based on the
3. The
Exponential
wire horsepower used
1.74
1.09
0.51
0.50
1.19
2.11
1.90
1.13
0.52
0.49
1.08
1.80
Air-
flow
Rate
KLa20 2
Standard
Oxygen
Transfer
C*0 Efficiency
(scfm) (1/hr) (mg/L)
375.3
257.7
127.6
115.5
240.9
354.8
362.2
245.8
125.2
128.7
265.8
402.1
numbers are based on
psia, and 36%
in accordance
model analysis
in this analysj
15
9
4
3
7
12
11
7
3
3
8
13
.08
.71
.15
.31
.72
.52
.93
.65
.50
.47
.11
.65
10.76
10.81
10.89
9.85
9.84
9.77
10.34
10.31
10.38
11.00
10.93
10.02
the adiabatic compression
relative humidity have
been used
(X)
20.67
19.59
17.12
6.83
7.64
8.28
12.35
11.60
10.53
17.74
19.83
21.73
equation.
Blower
Standard 3
Aeration Efficiency
(Ib 02/hp-hr)
Delivered Wire
5.
5.
5.
4.
3.
3.
4.
4.
4.
4.
5.
5.
Standard
inlet and
76
96
54
09
97
60
03
35
38
83
09
07
ambient
discharge
3.52
3.64
3.39
2.50
2.43
2.20
2.47
2.66
2.68
2.95
3.11
3.10
with Equations 4 and 6.
using
is is
Winkler
related
data.
to delivered horsep
ower by a
blower efficiency of
0.70, a coupling efficiency of 0.95, and a motor efficiency of 0.92 (an overall or combined efficiency of
0.612).
-------
TABLE 14. SUMMARY OF EQUILIBRIUM METHOD RESULTSj SANITAIRF, COARSE BUBBLE OIFFUSERS
00
en
Water
Depth
Delivered *
Power
Density
Date Run (ft) (hp/1000 ftj)
11/06/78 1
11/06/78 2
11/06/78 3
11/07/78 1
11/07/78 2
11/07/78 3
11/09/78 1
11/09/78 2
11/09/78 3
11/15/78 1
11/15/78 2
11/15/78 3
20
20
20
10
10
10
15
15
15
25
25
25
1. The delivered horsepower
conditions of 20°C, 14.70
pressures
2. Based on
3. The wire
1.74
1.09
0.51
0.50
1.19
2.11
1.90
1.13
0.52
0.49
1.08
1.80
Air-
flow
Rate
KLa20 2
Standard
Oxygen
Transfer
C*Q Efficiency
(acfm) (1/hr) (mg/L)
375.
257.
127.
115.
240.
354.
362.
245.
125.
128.
265.
402.
numbers are based on
paia, and 36%
were determined in accordance
the Equilibrium
horsepower uoed
model analysis
3 14.
7 9.
6 4.
5 3.
9 7.
8 12.
2 12.
8 7.
2 3.
7 3.
8 8.
1 13.
94
66
26
39
82
40
46
94
58
54
05
46
10
10
10
9
9
9
10
10
10
10
10
10
.76
.85
.78
.75
.78
.81
.18
.21
.31
.96
.95
.85
the adiabatic compression
relative humidity have
with
using
in this analysis is
Equations
4 and 6,
been used
(S)
20.49
19.55
17.35
6.94
7.70
8.23
12.70
11.91
10.67
17.99
19.73
21.49
equation.
. Blower
Standard •*
Aeration Efficiency
(Ib 02/hp-hr)
Delivered Wire
5.
5.
5.
4.
4.
3.
4.
4.
4.
4.
5.
5.
Standard
inlet and
71
95
62
15
00
58
14
47
44
89
06
02
ambient
discharge
3.49
3.64
3.44
2.54
2.45
2.19
2.53
2.73
2.72
2.99
3.09
3.07
Winkler data.
related to
delivered horsep
ower by a
blower ef
ficiency of
0.70, a coupling efficiency of 0.95, and a motor efficiency of 0.92 (an overall or combined efficiency of
0.612).
-------
TABLE 15. SUMMARY OF EXPONENTIAL METHOD RESULTS: ENVIREX COARSE BUBBLE DIFFUSERS
oo
Delivered *
Water Power
Depth Denaity
Date Run
01/08/79 1
01/08/79 2
01/09/79 1
01/09/79 2
01/10/79 1
01/10/79 2
01/10/79 3
01/10/79 4
01/11/79 1
01/11/79 2
01/11/79 3
01/19/79 1
01/19/79 2
01/25/79 1
01/25/79 2
1. The delivered
conditions of
pressures were
(ft) (hp/1000 ft-")
25
25
20
20
20
15
15
15
10
10
10
25
25
25
25
horsepower
20°C, 14.70
determined
2. Based on the Exponential
3. The wire horse
power used
0.49
1.01
1.69
0.49
1.02
1.79
1.08
0.50
0.49
1.10
1.93
1.64
0.50
1.65
0.51
Air-
flow
Rate KLa20 2
(scfm) (1/hr)
131.0 3.61
259.5 9.05
384.4 12. B8
126.5 3.56
252.0 7.68
377.3 11.56
251.6 7.46
125.7 3.51
119.1 3.15
242.5 7.05
363.2 11.36
394.7 12.68
133.2 3.81
400.3 12.89
136.4 3.71
Standard
Oxygen
Transfer
C*0 Efficiency
(mg/L)
11.20
10.47
10.44
10.03
10.75
10.19
10.19
10.22
9.76
9.76
9.73
10.85
10.97
11.00
11.31
numbers are based on the adiabatic compression
psia, and 36%
in accordance
model analysis
in this analysj
relative humidity have
with Equations 4 and 6
using W inkier data.
been used
•
Is is related to delivered horsep
(S)
18.39
21.59
16.87
14.98
15.82
11.29
10.97
10.33
6.25
6.88
7.36
20.46
18.70
20.93
18.31
equation.
. Blower
ower by a
Standard 3
Aeration Efficiency
(Ib 02/hp-hr)
Delivered Wire
5.10
5.77
4.94
4.96
5.01
4.10
4.40
4.42
3.93
3.89
3.57
5.19
5.19
5.30
5.09
Standard ambient
inlet and discharge
3.12
3.53
3,02
3.03
3.07
2.51
2.69
2.71
2.41
2.38
2.18
3.17
3.17
3.24
3.11
blower efficiency of
0.70, a coupling efficiency of 0.95, and a motor efficiency of 0.92 (an overall or combined efficiency of
0.612).
-------
TABLE 16. SUMMARY OF EQUILIBRIUM METHOD RESULTS: ENVIREX COARSE BUBBLE DIFFUSERS
Date
01/08/79
01/08/79
01/09/79
01/09/79
01/10/79
01/10/79
01/10/79
g° 01/10/79
01/11/79
01/11/79
01/11/79
01/19/79
01/19/79
01/25/79
01/25/79
Run
1
2
1
2
1
2
3
4
1
2
3
1
2
1
2
Water
Depth
(ft)
25
25
20
20
20
15
15
15
10
10
10
25
25
25
25
Delivered •*•
Power
Density
(hp/1000 ft3)
0.49
1.01
1.69
0.49
1.02
1.79
1.08
0.50
0.49
1.10
1.93
1.64
0.50
1.65
0.51
Air-
flow
Rate
(scfm)
131.0
259.5
384.4
126.5
252.0
377.3
251.6
125.7
119.1
242.5
363.2
394.7
133.2
400.3
136.4
KLa20 2
(1/hr)
3.67
8.23
12.86
3.64
7.89
11.76
7.48
3.51
3.32
7.22
11.50
12.75
3.83
12.68
3.88
c*o
(mg/L)
11.02
10.88
10.47
10.70
10.66
10.15
10.16
10.20
9.51
9.66
9.61
10.82
10.97
11.08
11.09
Standard
Oxygen
Tranafer
Efficiency
(SO
18.35
20.39
16.89
15.12
16.11
11.44
10.95
10.32
6.42
6.97
7.36
20.51
18.81
20.73
18.78
Standard
3
Aeration Efficiency
(Ib 02/hp-hr)
Delivered
5.09
5.45
4.95
5.01
5.11
4.16
4.39
4.42
4.04
3.94
3.57
5.20
5.22
5.25
5.22
Wire
3.12
3.33
3.03
3.06
3.12
2.54
2.69
2.70
2.47
2.41
2.18
3.18
3.19
3.21
3.19
1. The delivered horsepower numbers are based on the adiabatic compression equation. Standard ambient
conditions of 20°C, 14.70 psia, and 36* relative humidity have been uaed. Blower inlet and discharge
pressures were determined in accordance with Equations 4 and 6.
2. Based on the Equilibrium model analysis using Winkler data.
3. The wire horsepower used in this analysis is related to delivered horsepower by a blower efficiency of
0.70, a coupling efficiency of 0.95, and a motor efficiency of 0.92 (an overall or combined efficiency of
0.612).
-------
TABLE 17. SUMMARY OF EXPONENTIAL METHOD RESULTS: FMC COARSE BUBBLE DIFFUSERS
Date Run
03/06/79 1
03/06/79 2
03/06/79 3
Water
Depth
(ft)
15
15
15
Delivered *•
Power
Density
(hp/1000 ft3)
1.84
1.08
.50
Air-
flow
Rate
(acfm)
397.8
266.1
133.6
r\
KLa20
(1/hr)
12.51
7.44
3.57
c*o
(mg/L)
10.10
10.20
10.26
Standard
Oxygen
Tranafer
Efficiency
(SO
11.52
10.34
9.91
Standard 3
Aeration Efficiency
(Ib 02/hp-hr)
Delivered Wire
4.28 2.62
4.37 2.67
4.57 2.80
CO
1. The delivered horsepower numbers are baaed on the adiabatic compression equation. Standard ambient
conditions of 20°C, 14.70 psia, and 36% relative humidity have been used. Blower inlet and discharge
pressures were determined in accordance with Equations 4 and 6.
2. Baaed on the Exponential model analysis using Winkler data.
3. The wire horsepower used in this analysis is related to delivered horsepower by a blower efficiency of
0.70, a coupling efficiency of 0.95, and a motor efficiency of 0.92 (an overall or combined efficiency of
0.612).
-------
TABLE 18. SUMMARY OF EQUILIBRIUM METHOD RESULTS: FMC COARSE BUBBLE DIFFUSERS
Water
Depth
Date Run (ft)
03/06/79 1 15
03/06/79 2 15
03/06/79 3 15
Standard
Delivered * Air- Oxygen Standard 3
Power flow Transfer Aeration Efficiency
Density Rate KLa20 2 c*o Efficiency (Ib 02/hp-hr)
(hp/1000 ft3) (scfm) (1/hr) (mg/L) (%) Delivered Wire
1.84 397.8 12.27 10.14 11.35 4.21 2.58
1.08 266.1 7.25 10.21 10.08 4.26 2.61
.50 133.6 3.67 10.11 10.07 4.64 2.84
UD
o
1. The delivered horsepower numbers are based on the adiabatic compression equation. Standard ambient
conditions of 20°C, 14.70 psia, and 36% relative humidity have been used. Blower inlet and discharge
pressures were determined in accordance with Equationa 4 and 6.
2. Based on the Equilibrium model analysis using Winkier data.
3. The wire horsepower used in this analysis is related to delivered horsepower by a blower efficiency of
0.70, a coupling efficiency of 0.95, and a motor efficiency of 0.92 (an overall or combined efficiency of
0.612).
-------
this manner included the values of K[_a and standard wire aeration
efficiency (SWAE). Results of this comparison are summarized in Table 19.
Also presented in this table are the means and standard deviations of
ratios corresponding to the tests of each manufacturer.
TABLE 19. COMPARISON OF ANALYSIS METHODS
Ratios of Results from Exponential and Equilibrium Methods of Analysis
SWAEex/SWAEeq
System Mean Standard Deviation
Mean
Standard Number of
Deviation Tests
A
B
C
D
E
F
G
H
Overall
0.9927
0.9855
0.9837
1.0053
0.9817
0.9885
0.9928
1.0062
0.9900
0.0160
0.0204
0.0329
0.0211
0.0230
0.0189
0.0331
0.0238
0.0263
0.9954
0.9920
0.9911
1.0049
0.9878
0.9928
0.9974
1.0081
0.9946
0.0109
0.0150
0.0199
0.0147
0.0156
0.0121
0.0192
0.0160
0.0169
13
13
18
12
14
12
15
3
100
The magnitude of the !
-------
The graphs are all based on the data shown in the Exponential method
tables. It should be pointed out that straight-line connections are used to
connect data points for consistency and fairness to all manufacturers. The
reader may elect to use smoother curve fits.
Of the 15 graphs comparing equipment performance, 12 illustrate the
effects of changes in power and three show the effects of changes in water
depth. Each comparison graph includes data from all manufacturers. (Note:
Deflectofuser testing was carried out only at the 4.6-m (15-ft) water depth
and, therefore, is not included on graphs illustrating the effect of water
depth variation.) On graphs that illustrate the effects of power
variation, the data are divided into four groups, each representing a given
water depth. On graphs that illustrate the effects of water depth
variation, the plotted results correspond to the middle power level.
Parameters platted against water depth and power variation include standard
oxygen transfer rate (SOTR), standard oxygen transfer efficiency (SQTE),
and standard wire aeration efficiency (SWAE).
Water Depth RelationshiPS
The relationship between SOTR and water depth is shown in Figure 29.
The results of the seven manufacturers tested at multiple water depths are
presented. For each manufacturer and water depth, only a single result is
plotted. This plotted result represents the middle nominal power density
at which the manufacturer was evaluated. Note that the middle nominal
power density for all manufacturers tested is the same [26.3 W/m3 (1.0
hp/1000 ft^)] with the exception of System A, Norton, which was tested over
a lower power density range with a middle nominal power density of 13.2
W/m3 (0.5 hp/1000 ft3).
Data plotted in this graph are connected by straight Tines. Also,
where the data appear to be influenced by a manufacturer's configuration
change at different depths, only points from the same configuration are
connected (see data for System D, Kenics, and System F, Sanitaire).
It is apparent that increases in water depth resulted in increases in
SOTR. This is true for each manufacturer's configuration tested. In this
collection of data, the two highest curves represent fine bubble aeration
equipment. Coarse bubble aeration equipment is represented by generally
lower curves. The jet aeration equipment curve is in the middle above most
but not all of the coarse bubble aeration devices.
Comparative results of the SOTE vs. water depth for the seven
manufacturers tested at multiple water depths are presented in Figure 30.
Stipulations made for Figure 29 regarding plotting only the middle nominal
power density evaluated and connection of data points also apply to this
figure.
It is apparent that increases in water depth produced increases in
SOTE for each manufacturer configuration tested. The three highest curves
represent the fine bubble diffusers and jet aerators. Coarse bubble
92
-------
80
70
60
f-*
^ 50
OJ
O
S 40
£E
fe
« 30
20
I 0
0
• NORTON
• K6NJCS
A PENTECH
* FMC(Peorlcomb)
O SANtTAIRE
D BAUER
A ENVIREX
10 15
WATER DEPTH (ft)
20
25
Figure 29. Comparative plot of SOTR vs. water depth at middle power
density tested.
93
-------
50
40
30
UJ
B
CO
20
• NORTON
• KEN1CS
A PENTECH
• FMC (Peorlcomb)
O SANITAIRE
0 BAUER
A ENViREX
0 15
WATER DEPTH Cft)
20
25
Figure 30. Comparative plot of SOTE vs. water depth at middle
power density tested.
94
-------
aeration equipment is generally represented by lower curves. The variable
orifice diffusers showed no improvement over the other coarse bubble
diffusers.
In Figure 31, SWAE is plotted against water depth for the seven
manufacturers tested at multiple water depths. Stipulations made for
Figures 29 and 30 regarding plotting only the middle power density
evaluated and connection of data points also apply to this figure.
The data in Figure 31 indicate that the effects of increasing water
depth depend on the generic type of aeration equipment tested. While the
fine bubble diffusers appear to have been relatively unaffected by changes
in water depth, SWAE improved with increasing water depth for the coarse
bubble diffusers and jet aerators. In this collection of data, the two
highest curves represent the fine bubble diffusers while the jet aeration
equipment and coarse bubble diffusers generally grouped together in the
lower band of curves. The variable orifice diffuser results again were the
lowest. This graph indicates that coarse bubble devices appear to be
sensitive to changes in configuration (see data for System D, Kenics, and
System F, Sanitaire).
Delivered Power Density Relationships
Figure 32 is a plot of SOTR vs. delivered power density for the 3.0-m
(10-ft) water depth. This graph presents the results of the seven
manufacturers' equipment tested at this depth. The FMC Oeflectofuser, a
coarse bubble diffuser, was tested only at the 4.6-m (15-ft) water depth.
Results plotted in this graph and the 11 other delivered power density
relationship graphs (Figures 33 through 43) to follow are connected by
straight lines.
Increases in delivered power density resulted in increasing SOTR. The
two highest SOTR curves represent the fine bubble diffusion equipment.
Other generic types of aeration equipment produced similar but lower SOTR
results at this water depth.
SOTE is plotted against delivered power density for the 3.0-m (10-ft)
water depth in Figure 33. Results of the seven aeration systems tested at
this depth are presented in this graph. The FMC Deflectofuser was not
tested at this depth.
The coarse bubble and variable orifice systems (Kenics, Sanitaire,
Bauer, and Envirex) exhibited similar performance. The SOTE of these
systems remained the same or improved only slightly with increasing
delivered power density. The two fine bubble diffusers produced the
highest SOTE values, but in a pattern opposite to that of the coarse bubble
and variable orifice diffusers. Peak values for the fine bubble diffusers
occurred at the lowest delivered power density and declined for higher
power density levels. The jet system, like the fine bubble diffusion
systems, produced its peak SOTE value at the lowest delivered power
density.
95
-------
10
9
8
7
.-
£
I5
LJ
<
CO
3
2
I
0
» MORTON
• KENICS
A PENTECH
^ FMC(Peorlcomb)
O SAMTAIRE
D BAUER
i ENVIREX
H^-lVl-S
10 15
WATER DEPTH (ft)
Figure 31. Comparative plot of SWAE vs. water depth at middle power
density tested.
96
-------
OJ
o
80
70
60
50
40 h
20 -
10 -
0
• NORTON
• KENICS
A PENTECH
• FMCIPearlcomb)
0 SANITAiRE
n BAUER
A ENVIREX
0.5 1.0 1.5
DELIVERED POWER DENSITY (hp/IOOO ft3)
2.0
2.5
Figure 32. Comparative plot of SOTR vs. delivered power density
at 10-ft water depth.
97
-------
40
30
U
o
CO
20
10 -
• NORTON
• KENICS
A PENTECH
• FMC(Pearleomb)
O SANITAIRE
3 BAUER
A ENVIREX
0.5 1.0 1.5 2.0
DELIVERED POWER DENSITY (hp/1000ft3)
2.5
Figure 33. Comparative plot of SOTE vs. delivered power density at 10-ft water
depth.
98
-------
The relationship between SWAE and delivered power density for the
3.0-m (10-ft) water depth is shown in Figure 34. In this graph, data for
the seven manufacturers' equipment tested at this depth are presented. The
FMC Deflectofuser was not tested at this water depth.
All systems, with the exception of the jet aerators, demonstrated
their highest SWAE value at the lowest delivered power density level. For
the jet aeration system, peak SWAE performance occurred at the middle
delivered power density. The highest SWAE values were produced by the two
fine bubble aeration systems. All other systems exhibited nearly the same
SWAE results at this depth.
SOTR vs. delivered power density for the 4.6-m (15-ft) water depth is
plotted in Figure 35 for the eight aeration devices (including the FMC
Deflectofuser) tested at this depth.
It is apparent that increases in delivered power density resulted in
SOTR increases. The highest SOTR curves again represent the fine bubble
diffusion equipment. The order in SOTR values for the eight systems
tested, from highest to lowest, is as follows: Norton; FMC Pearlcomb;
Kenics; Pentech; Envirex, Sanitaire, and FMC Oeflectofuser grouped
together; and Bauer.
SOTE vs. delivered power density for the 4.6-m (15-ft) water depth is
illustrated in Figure 36. All eight manufacturers' systems were tested at
this depth.
The order in SOTE values, from highest to lowest, is as follows:
Norton, Pentech, FMC Pearlcomb, and Kenics, followed by the other coarse
bubble systems clustered closely together. The equipment producing fine
bubbles, Norton, FMC Pearlcomb, and Pentech, exhibited peak performance at
the lowest delivered power density. Equipment that produces coarse bubbles
generally showed the opposite trend, with peak values occurring at the
greatest delivered power density. The curves for most of the equipment are
relatively straight with the exception of the jet aeration system.
SWAE is plotted against delivered power density for the 4.6-m (15-ft)
water depth in Figure 37. All eight aeration systems were tested at this
depth.
The order in SWAE values, from highest to lowest, is Norton; FMC
Pearlcomb; Kenics; Pentech; FMC Deflectofuser, Envirex, and Sanitaire
grouped together; and Bauer. Five of the systems demonstrated little
variation in SWAE over the range of delivered power densities evaluated.
The systems that did exhibit significant variation over this range were
Norton, FMC Pearlcomb, and Pentech. These three systems all produce small
bubbles. Both Norton and FMC produced their peak SWAE values at the lowest
delivered power density, while for Pentech, the peak SWAE occurred at the
middle delivered power density.
99
-------
10
9
8
7
i_ 6
o 5
£
u 4
§ 3
Q.
-C
• NORTON
• KENICS
* PENTECH
• FMC (Pearlcomb)
O SANITAIRE
D BAUER
£, ENVIREX
0.5 1,0 1.5
DELIVERED POWER DENSITY (hp/1000 ft3)
v-a
2.0
2.5
Figure 34. Comparative plot of SWAE vs. delivered power
density at 10-ft water depth.
100
-------
80
70
60
^ 50
X
CO
2 40
*•_'
-------
40
30
LJ 20
o
CO
10
• NORTON
• KENICS
* PENTECH
• FMC(Pear)comb)
O SANITAiRE
D BAUER
A ENVIREX
0 FMC(Deflectofuser)
0.5 1.0 1.5
DELIVERED POWER DENSITY (hp/IOOOft3)
2.0
Figure 36. Comparative plot of SOTE vs. delivered power
density at 15-ft water depth.
102
-------
I
0.
-c
CD
CO
O
QJ
CO
0
9
8
7
6
2
I
0
0
• NORTON
• KENICS
* PENTECH
• FMC (Pearlcomb)
O SAN1TAIRE
Q BAUER
A ENVIREX
0 FMC(Deflectofuser)
0.5 1.0 1.5
DELIVERED POWER DENSITY (hp/1000 ft3)
2.0
Figure 37. Comparative plot of SWAE vs. delivered power
density at 15-ft water depth.
103
-------
Figure 38 is a plot of SOTR vs. delivered power density for the 6.1-m
(20-ft) water depth. Data for the seven aeration systems tested at this
depth are presented in this graph. The FMC Deflectofuser was not tested at
this depth.
It is clear from this figure that increasing delivered power density
resulted in increasing SOTR. The order of the system SWAE curves, from
highest to lowest, is Norton, FMC Pearlcomb, Sanitaire, Pentech, Envirex,
Bauer, and Kenics.
SOTE is plotted against delivered power density for the 6.1-m (20-ft)
water depth in Figure 39 for the seven manufacturers' devices tested at
this depth. The FMC Deflectofuser was not tested at this water depth.
Two opposite trends are apparent in this graph. Four aeration systems
(Norton, FMC Pearlcomb, Pentech, and Kenics) produced peak SOTE values at the
lowest delivered power density. Two coarse bubble systems and the variable
orifice system (Sanitaire, Envirex, and Bauer) showed peak SOTE at the
highest delivered power density. The order of the system SOTE curves, from
highest to lowest, is as follows: Norton, Pentech, FMC Pearlcomb,
Sanitaire, Envirex, Bauer, and Kenics.
The relationship of SWAE and delivered power density for the 6.1-m
(20-ft) water depth is shown in Figure 40. This graph presents data for
the seven aeration devices tested at this depth. The FMC Deflectofuser was
not tested at this water depth.
The Norton, FMC Pearlcomb, and Kenics systems achieved peak SWAE
values at the lowest delivered power density. The Sanitaire, Envirex, and
Bauer systems exhibited little variation of SWAE over the range of
delivered power densities tested. The Pentech system produced its peak
SWAE at the middle delivered power density. The order of the system SWAE
curves, from highest to lowest, is Norton, FMC Pearlcomb, Sanitaire,
Pentech, Envirex, Bauer, and Kenics.
Figure 41 shows the relationship of SOTR vs. delivered power density
for the 7.6-m (25-ft) water depth. Results of the seven manufacturers'
equipment tested at this depth are given in this graph. The FMC
Deflectofuser was not tested at this water depth.
It is clear that increasing delivered power density produced increases
in SOTR. The order of the system SOTR curves, from highest to lowest, is as
follows: Norton, FMC Pearlcomb, Kenics, Pentech, Envirex, Sanitaire, and
Bauer, although the Kenics curve crosses the latter four in the higher
portion of the range.
SOTE vs. delivered power density for the 7.6-m (25-ft) water depth is
shown in Figure 42. This graph presents data for the systems tested at
this depth. The FMC Oeflectofuser was not tested at this water depth.
In this graph, many system SOTE trends are apparent. The Norton and
Pentech data exhibit a steeply sloped linear relationship between SOTE and
104
-------
90
80
70
60
£50
o
eo
40
30
20
10
0
• NORTON
• KENICS
A PENTECH
• FMC (Pwrlcomb)
O SANITA1RE
0 BAUER
A ENV1REX
0.5 1.0 1.5
DELIVERED POWER DENSITY (hp/IOOO ft3)
2.0
Figure 38. Comparative plot of SOTR vs. delivered power
density at 20-ft water depth.
105
-------
50
40
30
LU
o
CO
10
• NORTON
• KENICS
A PENTECH
• FMC(Pearicomb)
O SANITA1RE
a BAUER
A ENV1REX
0 0.5 1.0 1.5 2.0
DELIVERED POWER DFNSITY (hp/IOOOft3)
Figure 39. Comparative plat of SOTE vs. delivered power
density at ZO-ft water depth.
106
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10
9
8
/->
f 7
o.
JC
£ 6
i
CM 5
.a
w 4
u
5 ^
co °
• NORTON
• KENiCS
A PENTECH
• FMC(Pearlcomb)
O SANITAIRE
n BAUER
A ENVIREX
0.5 1.0 i.5
DELIVERED POWER DENSITY (hp/IOOO ff3)
2.0
Figure 40. Comparative plot of SWAE vs. delivered power
density at 20-ft water depth.
107
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I lOr
100
90
80
70
CM 60
o
o
CO
50
40
30
20
lOh
0
• NORTON
• KENICS
A PENTECH
• FMC(Peorlcomb}
O SANITAIRE
n BAUER
A ENVIREX
0.5 1.0 1.5
DELIVERED POWER DENSITY (hp/IOOO ft3)
2.0
Figure 41. Comparative plot of SOTR vs. delivered power
density at 25-ft water depth.
108
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50 r
LU
O
CO
40
30
20
10
• NORTON
• KENICS
* PENTECH
• FMC(P«arlcomb)
O SANITAIRE
D BAUER
A ENV1REX
0.5 1.0 1.5
DELIVERED POWER DENSITY (hp/IOOOft3)
2.0
Figure 42. Comparative plot of SOTE vs. delivered power
density at 25-ft water depth.
109
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delivered power density. The peak value of SOTE for both systems occurred
at the lowest delivered power density. The peak SOTE value also occurred
at the lowest delivered power density for the FMC Pearlcomb system. Unlike
the first two systems, the SOTE vs. delivered power density relationship
of this system is not linear, but is steeply sloped in the lower portion of
the delivered power density range and horizontal in the higher portion of
the range. Other systems generally showed minor variations in SOTE. The
order of the system SOTE curves, from highest to lowest is Norton, FMC
Pearlcomb, Pentech, Envirex, Sanitaire, Kenics, and Bauer, although the
Kenics plot does cross the Envirex, Sanitaire, and Bauer curves between the
lower and middle portions of the range.
SWAE is plotted against delivered power density for the 7.6 (25-ft)
water depth in Figure 43 for the seven aeration devices tested at this
depth. The FMC Deflectofuser was not tested at this water depth.
The Norton and FMC Pearlcomb systems produced linear, downward sloping
curves with peak SWAE values at the lowest delivered power density. The
Pentech and Envirex systems also demonstrated similar relationships with
peak SWAE values occurring at the middle delivered power density. These
two systems, in addition to the remaining aeration systems, exhibited minor
variation in SWAE over the range of delivered power densities evaluated.
The order of the system SWAE curves, from highest to lowest, is as follows:
Norton, FMC Pearlcomb, Pentech, Envirex, Sanitaire, Kenics, and Bauer,
although the Kenics curve crosses the Sanitaire and Bauer curves between
the middle and upper portions of the range.
110
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0
9
8
7
-------
SECTION 7
PROBLEMS ASSOCIATED WITH CLEAN WATER TESTING
OVERVIEW
Prior to the initiation of clean water testing, a literature review
was conducted and equipment manufacturers and other experts in the field
were consulted. However, problems were still encountered, which often were
not immediately obvious. It was, in many cases, not until after several
tests were run that a problem became evident. During this evaluation, a
total of 144 tests were completed. Of these tests, only 100 were
acceptable for reporting. Reasons for the exclusion of test data from this
report included excessive variation of Ki_a values, unacceptable testing
conditions, and problems with primary data measurements. These problems
are discussed below in the order in which they were encountered.
DEGASSING OF HIGH LEVEL DISSOLVED OXYGEN SAMPLES
The original testing procedure was to measure the D.O. concentration
in all samples collected in the BOD bottles by using a D.O. meter and
probe. Following probe analysis, one of the four sample locations would be
analyzed using the Winkler method. A problem became apparent when the
probe measurements began to disagree with the Winkler method measurement of
the same sample. The disagreement was most evident in the equilibrium
(saturated) samples, where the oxygen concentration levels were the
highest. A number of potential explanations for this discrepancy were
explored. Among the possibilities investigated were chemical interference
with the Winkler method, improper concentration of the titrant used in the
Winkler method, probe membrane condition, probe stirring rate, probe
calibration procedure, and degassing of saturated samples. After examining
all of the above, it became evident that degassing of the high D.O. samples
was occurring. Degassing resulted from sample agitation by the D.O. probe
stirrer. This agitation caused the formation of small bubbles that
collected on the probe membrane and interfered with the probe's
performance.
A number of possible corrections for this problem were considered. An
attempt was made to modify the BOD bottle stirrer to produce less
agitation. However, modification of the stirrer shape or speed was not
successful. Because the equilibrium concentration of D.O. in water
increased as the water temperature decreased, the possibility of chilling
the samples was also considered. Although it appeared that this solution
would work, implementation was viewed as impractical. A decision was
instead made to analyze all samples by the Winkler method, which was
112
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expected to be unaffected by high level D.O. concentrations. Although the
Winkler method is a more time-consuming method for analysis, it is believed
that the improved quality of the data generated made the added effort
worthwhile.
BLOWER PULSATION
After a few months of testing, a blower pulsation problem was
discovered. The effect of blower pulsation on airflow measurements was not
obvious. No pulsating manometer fluid levels were detected, as one might
at first expect. When the oxygen transfer test results were reviewed with
the manufacturer and did not meet expectations, a decision was made to
examine the airflow measurement system in detail.
The air delivery system consisted of two separate air Tines, each made
for a different range of airflow rates. In each line, there were two
different types of airflow meters.. One was an orifice plate; the other was
an Annubar. Considerable care was exercised in the original design of the
air piping system. All pipes were placed in a single plane. In locating
the airflow measurement devices, proper upstream and downstream distances
were maintained from bends or other airflow disturbances.
Before any oxygen transfer testing began, a typical range of airflow
rates was run through each line at a typical range of line pressures. The
line pressures were simulated by throttling a valve downstream of the flow
meter section (no water was in the aeration tank at the time). Under these
conditions, nearly perfect agreement was obtained between the orifice plate
and Annubar at all flows tested. At that time, there was no reason to
expect problems of any kind.
Measurements taken after the tank was filled with water made it
clear that the agreement was no longer satisfactory. Furthermore,
certain phenomena were observed that were difficult to explain. At
low airflow rates, the Annubar manometer read negative instead of
positive. Extensive leak checks were performed to no avail, and a
conclusion was reached that a pressure disturbance of some type in the
line was occurring. Even more baffling, however, was the fact that by
changing the lengths of the manometer tubing, particularly on the
Annubar, varying differential pressure readings could be produced.
Short tubing lengths of approximately 1 m (3 ft) tended to produce
differential pressure readings that differed by as much as 5 cm (2
in.) of water from those produced by longer tubing lengths
[approximately 3.8 m (12 to 13 ft)]. Again, extensive leak checks
were performed to no avail. After consulting a number of experts in
the field, it was decided to use larger diameter tubing [6.4 mm (1/4
in.) I.D., instead of 4 mm (5/32 in.) I.D.] as well as to make the
tubing leads exactly the same length on both sides of the manometer.
After making these corrections, the problem was still experienced with
the Annubar but apparently not with the orifice plate. A decision was
made at that time to disregard readings from the Annubar, as it was
obviously being affected by some type of pressure disturbance in the
113
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line. Because the disturbance was located upstream from a check valve
and other fittings, it was felt that in some way they might be
interferring with the readings. It was not known at that time that
the cause of the problem was pulsation.
After several more tests were conducted, the pulsation problem
was discovered. During a second complete recheck of the air
measurement system, a valve was closed downstream of the Annubar such
that all the blower air was wasted through the waste valve. Under
these conditions, the Annubar manometer should have read zero since
there was no net flow past it. Instead, it registered approximately
1.3 cm (0.5 in.) of water in a negative direction with short tubing
leads and approximately 6.4 cm (2.5 in.) of water in a negative
direction with long tubing leads. It was at this time that pulsation
was suspected. The Annubar manometer reading went to zero when a
valve upstream of the flow jneter was shut off. This confirmed the
existence of a pulsation phenomenon.
In an attempt to dampen the pulsation, a decision was made soon
afterwards to install a large in-line air reservoir downstream of the
blower. This was one of the recommended procedures to help eliminate
pulsation. The tank used was cylindrical, 0.8 m (2.5 ft) in diameter
and 2.2 m (7.25 ft) high, with a capacity of approximately 1 HH (35
ft'). The tank air inlet was mounted near the top perpendicular to
the outlet mounted on the bottom. After the tank was installed,
essentially perfect agreement was obtained between the Annubar and the
orifice plate over the full range of flows and pressures. Further-
more, the manometer zeroed perfectly when the downstream valve was
closed and the manometer readings were not affected by short and long
tubing leads. The Annubar manometer no longer read negative at low
airflows as it did prior to the installation of the reservoir.
Although the exact amount of error is not known, it does appear
that the effect of pulsation on airflow measurements was greater at
the combination of low airflow rates and high water depths. This was
determined by a comparison of all the orifice plate and Annubar data
from the tests performed when the problem existed. A relationship
between the differences in the Annubar and orifice plate measurements
with air flow rate and water depth was evident. It appears that the
data collected at high airflow rates and low water depths were very
nearly correct; however, as the airflow rate decreased and the water
level increased, the error became much worse. It is interesting to
note that based on these findings it would appear that the pulsation
problem was worse at low line velocities.
It should be mentioned that after the problem was corrected, a
clean water test was run at the 6.0-m (20 ft) depth. The oxygen
transfer results obtained then met the manufacturers' expectations.
114
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EXCESSIVE '
-------
JET AERATOR PUMP POWER MEASUREMENT
With the exception of the jet aerator system, all systems tested
required power only to supply compressed air. As mentioned previously, air
power for all systems was calculated using the adiabatic compression
equation and typical full-scale values for blower and motor efficiencies
were assumed. In the testing of the jet system, pump power was measured
two ways. A wattmeter/recorder was used to monitor the actual power being
supplied to the pump. A pressure tap at the discharge side of the pump
allowed the measurement of total dynamic head (TDH) on the pump. The
initial analysis employed measured power values to determine the total
nominal horsepower values. The manufacturer indicated that because of the
relatively small volume of the clean water test tank, the pump being used
was of unusually low efficiency and the results would be neither fair to
the manufacturer nor representative of full-scale operational efficiencies.
It was also pointed out that in computing air power, the blower and motor
efficiencies being used were typical of full-scale operations. Following
discussions with the EPA Project Officer and the Project Consultant, it was
decided that full-scale efficiencies would be permitted. The TDH
measurements were used with pump curves to determine the pumping rate.
Using these flow rates, TDH measurements, and pump and motor efficiencies
typical of full-scale designs, the power values were calculated. The
following equation was used for this determination:
Ppd " Qp (
550 (34)
in which:
Ppd = Jet aerator pump delivered power
Qp = liquid flow rate produced by jet aerator pump
V water = specific weight of water at 20°C (62.4 lb/ft3)
Unfortunately, this calculation could not be easily generalized. It
was complicated by the fact that typical pump and motor efficiencies
differed, depending on whether submersible or dry pit pumps were employed.
For a submersible pump, the manufacturer recommended an overall efficiency
of 65.6% (assumed a pump efficiency of 75% and a motor efficiency of
87.5%). For a dry pit pump, the manufacturer recommended a typical overall
efficiency of 75.2% (assumed a pump efficiency of 86%, a motor efficiency
of 92%, and a coupling efficiency of 95%). The manufacturer also mentioned
that both types of pumps were used with nearly the same frequency. Since
it was desired to have only one set of horsepower numbers for the jet
aeration analysis, a decision was made to use the average of the typical
overall efficiencies for each type of pump. Thus, the jet aerator data
were reevaluated using an overall pump-motor-coupling efficiency of 70.4%.
If a design engineer is considering using power numbers from this report,
the pump power percentage of the total power should be adjusted up or down,
depending on the type of pump proposed.
116
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To calculate the SWAE of a jet aerator using a different pump
efficiency, the following factor may be applied:
Factor = 100X
100% - % PpwC(e' - 0.704)/e»] (35)
in which:
% Ppw = percent of total delivered aerator power supplied by pump
e1 = new assumed overall (pump, coupling, and motor) efficiency
This correction to the standard wire aeration efficiency, Nwo, may
be applied as follows:
Nrwo * Factor X Nwo (36)
in which:
N'wo - corrected value of standard wire aeration efficiency
TAP WATER FOAMING
During the testing of the fine bubble tube diffuser, significant
foaming problems developed after 12 tests on the system were completed.
Foaming was first experienced with a new batch of water. The onset of the
foaming seemed to correlate with the beginning of rain in the general area,
although not with any direct rainfall on the test tank.
The test tank foam was white, billowy, and at times as thick as 0.8 m
(2.5 ft). It did not cover the entire water surface, but usually occupied
two circular regions on the east and west walls of the test tank. These
circular regions were observed to be as large as 1.5 m (5 ft) in diameter.
The foam was very stable and tended to cling to the test tank walls. It
did not break down even after relatively long periods of aeration. It was
also not uncommon to see bubbles as large as 20 to 30 cm (8 ta 12 in.) in
diameter breaking on the surface of the tank during aeration.
The problem did not appear to be entirely confined to the surface of
the tank as water being pumped from the mid-depth location past an in-line
probe showed a tendency to form some bubbles. Other observations were that
foam formed fairly rapidly when the air was turned on and broke up
immediately when the air was shut off. Finally, the level of foaming
seemed to increase with either an increase in depth or an increase in
airflow rates.
When the foaming problem first developed, the local water supplier and
the wholesale distribution agency were contacted; however, they could shed
no direct light on the situation. A decision was made at that time to
suspend testing until the cause of the foaming could be determined and
corrected. It has been well substantiated that surface active agents can
have a tremendous effect on oxygen transfer tests.il/ Laboratory personnel
117
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attempted to determine the chemical characteristics of the tap water and
foam; the engineering staff conducted various field tests and procedures to
determine the source of the contaminants. A number of possible
contamination sources were considered, including the tap water supply, the
test tank and/or diffuser system, and the air suppy. At that time, the
preponderance of the laboratory and field evidence seemed to indicate that
the water supply was the source of the problem.
The laboratory staff determined that linear alkylate sulfonate (LAS),
the common surfactant present in detergents, was not measurable in the test
tank water. It was also determined that, upon coalescence, the bubbles in
the foam formed a deep brown liquid with well flocculated suspended solids
readily apparent. The staff also began an involved chemical extraction
procedure in an attempt to isolate the foaming agent. Other tests
conducted included surface tension, amine concentration, and pH.
Surface tension tests were performed on water samples from the
following locations: 1) the test tank, 2) the test tank water faucet, 3)
the plant's non-potable water supply tank, and 4) the bottled drinking
water supply (Sparkletts). The results of the tests showed that there was
essentially no difference in surface tension between the four samples and
that the surface tension obtained agreed with handbook values. This was
somewhat baffling, but additional testing revealed that the surface tension
of the condensed foam liquid was a little lower than that corresponding to
tap water. This information led to the belief that perhaps the foaming
problem was primarily a surface phenomenon, with aeration serving to
concentrate the surfactant on top of the tank.
Further proof of the concentrating phenomenon was obtained from
laboratory amine tests performed on both bulk liquid and foam samples.
Very high concentrations were found in the foam, while insignificant
concentrations were obtained in the bulk liquid. It was felt that the high
level of amines in the foam might be related to the cause of the foaming.
Among other things, the high amine concentration could have been due to the
presence of polymers in the water supply or to proteins from living cells.
It may be of interest to revfew some of the field tests that were
performed to determine the cause of the foaming problem. First,
small-scale aeration tests (500-ml beakers) were conducted on separate
water samples from the test tank, the test tank water faucet, the plant's
water supply tank, and the bottled drinking water supply. Surprisingly
enough, none of the samples, including the test tank sample, could be made
to foam at this small a scale. It was concluded that the scale of the test
was very important and that further testing would have to be conducted on a
sufficiently large scale.
To determine whether a cross-connection into the plant's non-potable
water supply system existed, it was decided to fill the aeration tank with
water from a separate distribution system; the plant's fire water system
was used. The aeration tank foaming was not reduced by this method,
however, and it was concluded that plant cross-connections were not the
problem.
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In an attempt to determine whether the problem was related to the
incoming water, air diffusers were installed in the plant's water supply
tank. This tank was much smaller than the aeration test tank used for the
clean water evaluation. Aeration produced essentially no foam. It was
then concluded that either the scale of the test was too small or that the
problem was not related to the incoming water, but to some other source
such as aeration test tank contamination.
Aeration test tank contamination was eventually eliminated as a
possibility. Six or seven hatches of water were used in the tank, and
between fillings, the tank was always hosed out thoroughly. Each
successive batch of water indicated no decrease in the severity of the
foam. This indicated that the source was either not present in the test
tank or that it was an extremely large source, which was unlikely.
Furthermore, it was determined that the foam could be vacuumed from the top
of the tank (a somewhat slow and incomplete process) and that the foam did
not return to its original level. With the next water batch, however, the
foam returned completely. This indicated that the source of the foaming
was not the aeration test tank, the air supply, or atmospheric
contamination.
Since the causative agent was felt to be in the incoming water, a
decision was made to try and remove the contaminant by some means. It was
believed that surfactant was probably an organic compound at a fairly low
concentration; consequently, removal fay carbon adsorption seemed a likely
possibility.
Concern was expressed by EPA that pretreatment of the water should be
avoided, if possible, since this was not done for the earlier manufacturers
in the study. It was conceded that to avoid further delays, an activated
carbon column should be installed in an attempt to remove the surfactant
before it entered the aeration test tank.
The column was initially operated in a downflow mode, but large carbon
particles escaped around the retaining plate at the bottom of the column.
Fortunately, this was discovered before any attempt was made to fill the
aeration tank. To correct this problem, a decision was made to operate the
column in an upflow mode. The carbon column piping was revised to
accommodate this change in operation. The carbon column was backwashed
extensively to get rid of carbon fines. Unfortunately, the first batch of
aeration tank water showed that this operation had not been successful. A
noticeable quantity of fine colloidal carbon was present in the treated
water, so much, in fact, that the water took on a deep black appearance.
The fine colloidal carbon particles had an almost neutral buoyancy and were
carried out of the column at even the lowest of surface loading rates. It
was interesting to note that under aeration the treated tank water produced
no trace of foam or other surfactant phenomena of any kind. The fine
colloidal carbon in the water was not acceptable, however, so a means of
correcting the problem was sought.
It was felt that the escape of fine colloidal carbon could not be
controlled in the upflow mode of operation, and a decision was made to
113,
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revert back to the downflow mode. This time, however, a 20-cm (8-in.) bed
of 120 silica sand was baclcwashed down to the bottom of the column in an
attempt to filter the 112 to #40 activated carbon. This attempt was only
partially successful and an additional 13 cm (5 in.) of #12 silica sand was
added in the same manner. After approximately 8 hr of downflow operation
with a 10-min contact time [3,2 L/sec (50 gpm)]» essentially no carbon or
sand was observed in the carbon column effluent. The aeration test tank
was filled to the 3-m (10-ft) depth with this treated water, but although
the water was noticeably clearer than regular tap water, it soon became
apparent that a portion of the surfactant still remained. Under aeration
no buildup of foam occurred as before, but surface bubbles were noticeably
larger than in regular tap water [bubbles as large as 10 to 13 cm (4 to 5
in.) in diameter were observed]. While the carbon column removed the major
portion of the surfactant, it was obvious that a greater contact time was
required to achieve complete removal. To increase the contact time to 20
fflin, the flow rate through the carbon column was reduced to 1.6 L/sec (25
gpm). Unfortunately, even this contact time was insufficient to achieve
complete surfactant removal. It was not considered feasible to go to even
lower flow rates through the carbon column, or on the other hand, to use a
larger carbon column. With this in mind, it was decided to try and show
that the available water was equivalent to previously used "clean" water as
far as the oxygen transfer testing was concerned.
To show the effect of both the surfactant and the activated carbon
process on the oxygen transfer results, the results of five tests were
analyzed for the 3.0-m (10-ft) water depth and the 26.3-W/m3
(l.O-hp/1000 ft^) power level. The only difference between these
tests was the quality of the water used in each case. The first data
set evaluated was from a background test (8/29/78) conducted at a time
before the foaming problem was observed. The second data set was from
a test (9/29/78) conducted when the foaming problem was very much in
evidence. The third test (10/13/78) was conducted with water that was
obtained from the upflow carbon column operation and, as a result,
contained a great deal of the fine colloidal carbon, but no evidence
of a surfactant, for the fourth test (10/19/78), the test tank water
was obtained from the high-rate [3.2-L/sec (50-gpm)] carbon column
operation in a downflow mode; some evidence of a surfactant was
present. For the fifth test (10/26/78), the test tank water was
obtained from the low-rate [1.6-L/sec (25-gpm)3 carbon column
operation in a downflow mode. Again, same evidence of a surfactant
was present. The results of these five tests are compared in Table 20
below.
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TABLE 20. FOAMING PROBLEM COMPARISON TESTS
Airflow
Standard
Oxygen
Transfer
Date
Average Delivered
Water Depth Power Level Rate La20 Efficiency
Run (ft) {hp/1000 ft3) (scfm) (1/hr)
8/29/78
9/29/78
10/13/78
10/19/78
10/26/78
2
1
1
1
1
10.06
10.04
9.98
10.12
10.06
1.16
1.18
1.17
1.22
1.19
276.6
277.6
274.5
284.0
278.8
13.02
13.37
14.02
13.98
14.65
11.31
11.54
12.06
11,76
12.41
The first two tests indicate that the surfactant had no effect on SOTE
transfer. The SOTE obtained with foam in the tank was 11.556 as compared to
11.3% without it. Even though this comparison was noted early in the
foaming problem investigation, it was still considered necessary to
eliminate the cause of the problem. The credibility of the tests might be
questioned by the presence of foam in the water no matter how many
comparative tests gave evidence to the contrary.
Additional proof that the surfactant did not affect the oxygen
transfer results was obtained after the carbon column was installed. In
the test with no surfactant present (10/13/78 - Run 1), the SOTE obtained
was 12.1%. The following two tests both had some surfactant remaining in
the water and yielded an average SOTE identical to that from the 10/13/78
run.
After the carbon adsorption unit was installed, the data indicated
that the SOTE values increased slightly. The average of the three "carbon
adsorption" tests produced an SOTE of 12.1% as compared to 11.4% for the
two tests before the carbon adsorption unit was Installed. This was an
increase of 5.7% and would appear to be significant. This phenomenon was
best explained by the possibility that the carbon column removed an oxygen
transfer inhibiting compound(s) that occurs naturally in local tap water.
It was also possible, however, that the change in SOTE was not related to
the carbon column at all, but was due to other factors such as water
temperature variation [water temperature decreased steadily from 24.5°C
(76.1°F) during the first test to 21.9°C (71.4°F) during the last test].
After considering the results of the first four comparison tests (the
fifth test was not run until later), a decision was made to go ahead and
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run the remaining fine bubble tube diffuser tests on water from the carbon
column. Unfortunately, the results of these latter tests strongly
supported the hypothesis that the activated carbon process (or possibly
some other factor) was having a significant influence on the oxygen
transfer results. The transfer efficiencies obtained exhibited an increase
of 13 to 15% over what would be projected from tests at the 3.0- and 7.6-m
(10- and 25-ft) depths. Pounds of oxygen transferred per wire
horsepower-hour vs. delivered power was plotted for the various depths. It
was evident that the curves for the 4.6- and 6.1-tn (15- and 20-ft) depths
were on considerably higher curves than those for the 3.0- and 7.6-m (10-
and 25-ft) depths. This would not be expected if the tests were conducted
on water of identical quality. The tests for the 4.6- and 6.1-m (15-and
20-ft) depths were conducted with carbon treated water, while the others
were conducted on non-foaming tap water. It was clear from the plot that
the effect was very significant for all power levels. Furthermore, the
magnitude of the difference was much more significant than what would have
been predicted from the comparison tests at the 3.0-m (10-ft) water depth.
A decision was made to run the rest of the tests for the study without
the carbon treated water. As mentioned previously, the surfactant causing
the foaming problem did not appear to be affecting the oxygen transfer
results, whereas the use of the activated carbon process did. It should be
mentioned that it is likely that the oxygen transfer results obtained from
the carbon treated water are closer to actual "clean" water transfer
results. It appears, however, that there may have been some natural
surfactant present in the tap water from the start of the study. Since our
main objective was to compare the different manufacturers' equipment under
the same conditions, it did not seem appropriate to use the carbon treated
water only for the manufacturers that remained to be tested. The fine
bubble tube diffuser tests for the 4.6- and 6.1-m (15- and 20-ft) water
depths that were conducted with carbon treated water initially were
repeated using untreated tap water.
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SECTION 8
FOLLOW-ON RESEARCH ACTIVITIES
To determine the wastewater correction factors associated with some of
the generic oxygen transfer devices evaluated in the clear water study,
LACSD, in conjunction with EPA, conducted full-scale oxygen transfer tests
in mixed liquor (Aeration Equipment Evaluation - Phase II). Not all of the
equipment evaluated during Phase I could be tested in Phase II due to space
and manpower limitations. A decision was made, therefore, to test the
three most promising devices from a potential energy conservation
standpoint. The tests were carried out in parallel trains at the
Districts' Whittier Narrows Water Reclamation Plant. The aeration systems
selected included
o fine bubble (dome/disc) diffusers applied in a total floor
coverage configuration,
o fine bubble tube diffusers applied in a dual aeration
configuration, and
o jet aerators.
Operation of the three aeration systems in mixed liquor began in
December 1980. For 6 mo, information on oxygen transfer and mechanical
reliability was collected on the three systems. After this initial
screening, the most promising system was tested on an expanded scale for 8
mo at nominal aeration detention times of 4 to 6 hr. This system was the
fine bubble ceramic (dome/disc) diffusers. Mixed liquor testing was
completed in December 1982. A final report of the results of the Phase II
study is in preparation.
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REFERENCES
1. Personal communication with Dominguez Water Corporation, Long
Beach, CA, September 20, 1978.
2. Cusick, C.F. Flow Meter Engineering Handbook. Fourth Edition,
Honeywell, Fort Washington, PA, 1968. pp. 1-14, 57-79,
85-165.
3. Fluid Meters, Their Theory and Application. Fifth Edition, ASME,
1959.
4. American Public Health Association. Standard Methods for the
Examination of Water and Wastewater. 14th Edition, Washington,
D.C., 1975.
5. Spink, L.K. Principles and Practice of Flow Meter Engineering.
Ninth Edition, Foxboro Company, Foxboro, MA, 1967. pp. 3-127,
415-530, 545-564.
6. Metcalf and Eddy, Inc., Wastewater Engineering. McGraw-Hill, New
York, NY., 1972.
7. Lewis, W.K. and W.C. Whitman. Principles of Gas Adsorption.
Ind. Eng. Chem., 16:1215, 1924.
8. Proceedings: Workshop Toward an Oxygen Transfer Standard. Edited
by W. C. Boyle. EPA 600/9-78-021, NTIS No. PB-296557/2, U.S.
EPA, Cincinnati, OH, April 1979.
9. Stukenberg, J.R., V.N. Wahbeh, and R.E. McKinney. Experiences in
Evaluating and Specifying Aeration Equipment. Journal WPCF,
49(l):66-82, January 1977.
10. Beveridge, G.F.G. and R.F. Schechter. Optimization - Theory and
Practice. McGraw Hill, New York, NY, 1970. pp. 453-456.
11. Stenstrom, M.K., L.C. Brown, and H.J. Hwang. Oxygen Transfer
Parameter Estimation. Journal of the Environmental Engineering
Division, ASCE, 107(EE2):379-397, April 1981.
12. Houck, O.K. and A.G. Boon. Survey and Evaluation of Fine Bubble
Dome Oiffuser Aeration Equipment. EPA 600/2-81-222, NTIS No.
PB82-105578, U.S. EPA, Cincinnati, OH, September 1981.
124
-------
APPENDIX A
AIRFLOW METER EQUATIONS
The equations that follow can be used to determine airflow rate
at standard conditions based on measured data. The orifice plate and
Annubar equations are shown separately. Standard conditions for
airflow measurement are 20°C (68°F), 101.3 kPa (14.7 psia), and 36%
relative humidity.
ORIFICE PLATE AIRFLOW EQUATIONS
For a definition of the variables used in this appendix
subsection, refer to the Nomenclature section of this report. The
following orifice plate airflow equation was used for this project:
Qo a(K)(S0)(Fa)(Fra)(Fpe)(Fwv)Ymio) (0.01934pa + 0.491pfo)
J (Tf + 460) (Al)
The equations common to both orifice plates are shown below:
Fa = 2 x 10-5 (Tf + 460) + 0.9891 (A2)
For ZK red fluid-filled manometer:
- n n544fl (0-01934pa + 0.491pf)
V« IJ^™™LJ N HI mi _ ==atinr-
(A3)
(Tam + 460)
For water-filled manometer:
n «,,,,(tJ.01934pa •«• 0.491pf)
- 0.04331 Kd • L
(iam + 46U) (M)
Fpe = 1.333 x 10'5 (Tf + 460) + 0.9930 (AS)
125
-------
wv
in which:
Pw]
- (pwi/(0.01934pa + 0.491pf)
- 0.3775 [pwi/(0.01934pa + 0.491pf)]
(0.01934pa + 0.491pf)(RH)(pvpT)
1.934pa
(A6)
(A7)
and
PvpT =
8.13254 - / 1764.42
,236.139 + Tw,
(0.01934)
(A8)
3-in. Orifice Plate
K - 1256.93
S0 = -0.001 /]
i.M2 -f Re-96,800 \2 +0.19658
20,000
(for Re from 19,000 to 120,000)
Y = 1 - 0.01141 h0/(0.01934pa + 0.491pfo)
4-in. Orifice Plate
K = 2201.56
Sft = - 0.002/12.527 -f Re"383
100
3,000
,000 /
).32871
(for Re from 30,000 to 500,000)
Y = 1 - 0.01257 h0/(0.01934pa + 0.491pfo)
Note:
Re « 28.943 Q/du
in which:
U = 2.218 x 10~5 (Tf + 460) + 0.00641
126
(A9)
(A10)
(All)
(A12)
(A13)
(A14)
-------
ANNUBAR AIRFLOW EQUATIONS
For a description of the variables used in this appendix
subsection, refer to the Nomenclature section of this report.
following Annubar airflow equation was used.
The
Qa = K'
in which:
Fm =
wv
^.491(pt-pfa)(Tf+460i
dO(Fm)(Fpe)(Fwv)(Pfa)
(See Eqs. A3 and A4)
(See Eq. A6)
'(O.Q1934pa + Q.491pt)\0.2857
+ Q.491Pfay
-1
(A15)
(A16)
3/4-in. Annubar
K »
rpe •
2-in. Annubar
K =
100.55
1.6989 x 10-5 (Tf
742.58
460) + 0.99097
(A17)
Fpe = (See Eq. A5)
3-in. Annubar
K = 1690.74
Fpe = (See Eq. A5)
127
-------
APPENDIX B
PREAMBLE TO APPENDICES C THROUGH J
The results of clean water testing for the eight aeration systems
evaluated in this study were summarized previously in Section 6 in
Tables 3 through 18. Two tables were prepared for each system, one
based on the Exponential method of analysis and the other on the
Equilibrium method of analysis. Also in Section 6, the oxygen transfer
performance of these systems was compared graphically in Figures 29
through 43.
In addition to the above graphs that compared the performance of
all the manufacturers' equipment, a total of 69 graphs were prepared
to summarize individual equipment performance for the eight aeration
systems tested. These graphs are presented for each system in
Appendices C through J. Nine graphs each were generated for Norton,
FMC (fine bubble tubes), Pentech, Kenics, Bauer, Sanitaire, and
Envirex (Appendices C through I, respectively), while just six graphs
were produced for the FMC Deflectofuser (Appendix J) because it was
tested at one water depth only.
Data from all water depths and power levels tested are included
in the individual performance graphs. The nine graphs for each of the
first seven systems listed above (Appendices C through I) illustrate
in order the following relationships: Airflow Rate vs. Delivered
Power Density, Ki_a20 vs. Delivered Power Density, SOTR vs. Delivered
Power Density, SOTE vs. Delivered Power Density, SWAE vs. Delivered
Power Density, SOTR vs. Water depth, SOTE vs. Water Depth, and SWAE
vs. Water Depth. Only the first six of these graphs are included for
the FMC Deflectofuser (Appendix J).
In the plots illustrating the effects of power variation, points
representing the same water depth are connected. For the graphs
depicting the effects of water depth variation, points of equal
nominal power are connected. All connections between points were made
using straight lines; the reader may elect to use smoother curve fits.
128
-------
APPENDIX C
INDIVIDUAL PERFORMANCE RESULTS FOR
NORTON FINE BUBBLE DOME DIFFUSERS
A total of 13 acceptable tests were conducted on the Norton fine
bubble dome diffuser system in this study. The results of these tests were
summarized tabularly in Tables 3 and 4 in Section 6 and are presented
graphically here in Figures C-l through C-9.
The effect of variations in airflow rate on delivered power density is
shown in Figure C-l for the various water depths. As expected, an increase
in airflow rate resulted in an increase in delivered power density.
Figure C-2 shows the relationship between nominal power density and
delivered power density. The effect that is generally demonstrated is that
as power density increased, the differences between nominal and delivered
power densities increased. The differences became larger with decreasing
water depth.
Figure C-3 illustrates the relationship between delivered power
density and K[_a2o- In tn^s plot, the K|_a2Q r*te of increase is initially
high, then appears to decrease slightly with increasing delivered power
density. Also apparent is that increasing water depth resulted in
decreasing Kj_a2Q values.
SOTR is plotted against delivered power density in Figure C-4. SOTR
is expressed in both U.S. customary units (left vertical axis) and SI units
(right vertical axis). For the Norton system, an increase in delivered
power density produced an increase in SOTR. The rate of SOTR increase of
this system was essentially linear at the 3.0-m (10-ft) water depth. Both
nonlinearity and the rate of increase in SOTR increased with increasing
water depth. The nonlinearity effect was characterized by an initial rapid
increase in SOTR at low delivered power densities followed by a lower rate
of increase at higher delivered power densities. The effect of increasing
water depth on SOTR was greater than on K|_a20- for every system tested,
the same trend was noted; SOTR increased with increasing water depth.
Figure C-5 is a plot of the relationship between SOTE and delivered
power density. SOTE values are clearly the greatest at the lowest
delivered power density level tested. For three of the four water depths,
the rate of SOTE decrease was greater at the lower delivered power
densities than the higher ones. Also evident in this graph is the
existence of a relationship between SOTE and water depth; an increase in
129
-------
500
§ 400
o
CO
w
if 300
cr
200
100
O I 0 ft DEPTH
— D I 5 ft DEPTH
A 20ft DEPTH
O 25ft DEPTH
200
150
100
50
o
UJ O-
cc £
UJ
LJ
O
2.5
2.0
1.5
1.0
0.5
0
O i o f t DEPTH
D I 5 ft DEPTH
A 20ft DEPTH
O 25ft DEPTH
0 0.5 1.0 1.5 2.0
NOMINAL POWER DENSITY(hp/IOOO ff3)
Figure C-2. Delivered power density vs. nominal power density
for Norton fine bubble dome diffusers.
130
-------
o
CJ
o
25
20
I 5
10
5
O I 0 ft DEPTH
D i 5 ft DEPTH
A 20ft DEPTH
O 25ft DEPTH
'0 0.5 1.0 1.5 2.0 2.5
DELIVERED POWER DENSITY (hp/IOOO
Figure C-3. K^g vs. delivered power density for Norton fine
bubble dome diffusers.
120
100
r\
f • 80
O
$ 60
or
5 40
CO
20
0;
O I 0 ft DEPTH
D I 5 ft DEPTH
A 20ft DEPTH
O 25ft DEPTH
50
40
30
20
10
\ i i i in
"0" 0.5 i.O 1.5 2.0 2.5
DELIVERED POWER DENSITY (hp/IOOO ft3)
en
Figure C-4. SOTR vs. delivered power density for Norton fine
bubble dome diffusers.
131
-------
UJ
o
CO
50
40
30
20
10
O I 0 ft DEPTH
a I 5 ft DEPTH
A 20ft DEPTH
O 25ft DEPTH
0 0.5 1.0 1,5 2.0 2.5
DELIVERED POWER DENSITY (hp/IOOO ft3)
Figure C-5. SOTE vs. delivered power density for Norton fine
bubble dome diffusers.
/-N
C-
J=
1
^^
.C
-------
water depth resulted in an improvement in SOTE. In fact, this relationship
is exhibited by the equipment of every manufacturer tested in this study.
SWAE vs. delivered power density is shown for Norton in Figure C-6.
SWAE is given in both U.S. customary units and SI units. This graph is
possibly the most important of those presented; the sensitivity or
insensitivity of a system's efficiency to variations in delivered power
density is demonstrated. For this system, the highest SWAE values occurred
at the lowest delivered power density. The trend of the data is such that
SWAE decreased almost linearly with increasing values of delivered power
density. Unlike the preceding two figures, an increase in water depth
generally did not result in increased values of the dependent variable
(vertial axis). The effect of increasing water depth on this system
appears minimal. Results representing various depths are clustered very
closely for this system, indicating an insensitivity of the system to
changes in water depth.
Figure C-7 illustrates the relationship between SOTR and water depth,
with SOTR expressed in both U.S. customary units and SI units. An increase
in water depth implies that for a given nominal power density to be
maintained [i.e., 26.3 W/m3 = (1.0 hp/1000 ft3)], the delivered power must
be increased by a comparable amount. It might, therefore, be expected that
an increase in water depth would result in increased SOTR. This trend is
indicated by results from each of the seven aeration systems tested at
multiple water depths. The Norton system exhibited an almost linear
increase in SOTR with increasing water depth. The highest SOTR values were
observed at the highest nominal power density.
SOTE vs. water depth is plotted in Figure C-8. An increase in water
depth produces an increase in pressure on discharged air in addition to
increasing the detention time of air bubbles in the tank liquid. The
theoretical impact of such changes is an increase in SOTE at greater
depths.
Increasing SOTE with increasing water depth was observed for each of
the seven aeration systems tested at multiple water depths. With the
Norton fine bubble, an almost linear increase in SOTE was observed with
increasing water depth. The highest values of SOTE were associated with
the lowest nominal power density.
Figure C-9 depicts the Norton system's relationship between SWAE and
water depth, with SWAE expressed in both U.S. customary units and SI units.
In this illustration, SWAE appears to have been unaffected by changes in
water depth. This system's peak SWAE performance was at the 6.1-m (20-ft)
water depth. It is apparent that variations in nominal power density
significantly affected SWAE. Optimum SWAE occurred at the lowest nominal
power density evaluated.
133
-------
o
6
or
120
100
80
60
20
Qi
O 0.3 hp/!000ft3
Q 0,5 hp/IOOO
A 1.0 hp/IOOO f|3
10 15 20 25
WATER DEPTH (ft)
30
50
40
30
20
10
0
<=n
Figure C-7. SOTR vs. water depth for Norton fine bubble
dome diffusers.
LU
O
CO
50
40
30
20
SO
0,
O 0.3 hp/IOOO ft3
n 0.5 hp/IOOO ft3
A l.O hp/IOOO ft3
10 15 20
WATER DEPTH (ft)
25
Figure C-8. SOTE vs. water depth for Norton fine bubble dome
diffusers.
134
-------
o.
01
^
"5
N.
-------
APPENDIX D
INDIVIDUAL PERFORMANCE RESULTS FOR FMC
FINE BUBBLE TUBE DIFFUSERS
A total of 13 acceptable tests were conducted on the FMC
Pearlcomb fine bubble tube diffusers in this study. Test results for
this system were summarized tabularly in Tables 5 and 6 (Section 6)
and are shown graphically here in Figures D-l through D-9.
Figure D-l illustrates the effect that variations in airflow rate
have on delivered power density at the various water depths. As
expected, an increase in airflow rate produced an increase in
delivered power density.
The relationship between nominal power density and delivered
power density is shown in Figure D-2. As with the Norton system, as
power density increased, discrepancies between nominal and delivered
power densities increased. The discrepancies became larger as water
depth decreased.
The relationship of delivered power density to K|_a2Q is plotted
in Figure D-3. For this system, K|_a2Q increased linearly with
increasing power density. It is not apparent that increased water
depth had any affect on K|_a2Q values for the FMC fine bubble tube
diffuser.
Figure D-4 is a plot of SOTR vs. delivered power density. This
plot gives SOTR values in both U.S. customary units (left vertical
axis) and SI units (right vertical axis). An increase in delivered
power density results in an increase in this system's SOTR. The rate
of increasing SOTR appears to have been almost constant at the 6.1-m
(20-ft) and 7.6-m (25-ft) water depths. At lower water depths, a
small degree of nonlinearity was characterized by a higher rate of
increase in SOTR values at low delivered power densities. Also
apparent is the significant effect of increasing water depth on SOTR,
an effect much greater than that observed on
The relationship between SOTE and delivered power density is
graphed in Figure D-5. SOTE decreased moderately with increasing
delivered power density except at the 7.6-m (25-ft) water depth where
the decrease was more evident. An increase in water depth resulted in
higher SOTE values.
136
-------
500
400
o
CO
j£ 300
QC
I 200
_j
5 100
O I Oft DEPTH
D I 5 ft DEPTH
A 20ft DEPTH
O25ft DEPTH
200
150
100
50
u
«
CO
0 0,5 1.0 1,5 2.0 2.5
DELIVERED POWER DENSITY(hp/IOOO ft3)
Figure D-l. Airflow rate vs. delivered power density for
FMC fine bubble tube diffusers.
2.5
2.0
- 1.5
o
o
o
Q "s.
UJ Q-
tr £
UJ
UJ
O
i.O
0.5
O 10 ft DEPTH
O I 5 ft DEPTH
A 20ft DEPTH
O 25ft DEPTH
'0 0.5 1.0 1.5 2.0
NOMINAL POWER DENSITY(hp/l000 ff3)
Figure D-2. Delivered power density vs. nominal power density
for FMC fine bubble tube diffusers.
137
-------
o
OJ
o
25
20
! 5
I 0
5
O 1 0 f t DEPTH
D t 5 ft DEPTH
A 20ft DEPTH
O2 5ft DEPTH
'0 0.5 1.0 1.5 2.0 2.5
DELIVERED POWER DENSITY {hp/l000
Figure D-3. KLa2n vs< delivered power density for FMC fine
bubble tube diffusers.
cj
O
IT
h-
O
CO
!20
100
80
60
40
20
O 10 ft DEPTH
D I 5 ft DEPTH
A 20ft DEPTH
O25ft DEPTH
50
40
30
20
! 0
1 1 1 j |Q
0 0.5 1 .0 1 .5 2.0 2.5
DELIVERED POWER DENSITY (hp/IOOO ft3)
Figure D-4. SOTR vs. delivered power density for FMC fine
bubble tube diffusers.
138
-------
a*
«-/
UJ
K
O
CO
30
25
20
15
10
5
O 1 0 ft DEPTH
n I 5 ft DEPTH
A 20 ft DEPTH
O25ft DEPTH
'0 0.5 1.0 1.5 2.0 2.5
DELIVERED POWER DENSITY (hp/1000 ft3)
Figure D-5. SOTE vs. delivered power density for FMC fine
bubble tube diffusers.
6.0
y~v
e_
I 5.0
JZ
<35
-| 4.0
\
g 3.0
S 2.0
M I .0
O I 0 ft DEPTH
D I 5 ft DEPTH
A 20ft DEPTH
O 2 5 ft DEPTH
3.0
2.0
. 0
0 0.5 1.0 1.5 2.0 2,5
DELIVERED POWER DENSITY(hp/IOOO ft3)
eg
O
e»
Figure D-6. SWAE vs. delivered power density for FMC fine
bubble tube diffusers.
139
-------
SWAE is plotted against delivered power density in Figure D-6,
with SWAE provided in both U.S. customary units and SI units. For
this fine bubble system, the highest SWAE values occurred at the
lowest delivered power density. SWAE decreased almost linearly with
increasing values of delivered power density. Increasing water depth
did not always result in increased SWAE values, however. The effect
of increasing water depth on this system's SWAE appears to have been
small. Results representing various water depths at a given power
level are clustered closely for this system, indicating an
insensitivity of the system's SWAE to changes in depth.
The relationship of SOTR to test tank water depth is illustrated
in Figure 0-7, with SOTR given in both U.S. customary units
and SI units. This system exhibited an almost linear increase in SOTR
with increasing water depth, with the highest SOTR observed at the
highest nominal power density.
Figure D-8 is a plot of SOTE vs. test tank water depth.
Increasing SOTE with increasing water depth was noted for this system .
as with each of the other six aeration systems tested at multiple
water depths. Two of the three nominal power density curves indicate
that the SOTE rate of increase dropped off slightly at the 7.6-m
(25-ft) water depth with this system. The remaining curve indicates a
somewhat linear relationship. In this graph, the highest SOTE values
are associated with the lowest nominal power density.
This system's relationship of SWAE to water depth is shown in
Figure D-9. SWAE is expressed in both U.S. customary units and SI
units. As with the Norton system, SWAE appears unaffected by changes
in water depth. For this system, it is unclear what water depth
produced the best performance. It is apparent, however, that
variations in nominal power density significantly affected SWAE
results. Optimum SWAE occurred at the lowest nominal power density.
140
-------
«
o
o
CO
120
100
80
60
40
20
Oj
O0.5 hp/IOOO ft3
D i .0 hp/IOOO ft3
A ! .5 hp/IOOO ft3
0
10 15 20 25
WATER DEPTH (ft)
30
50
40
30
20
10
ty>
je
v
Figure D-7. SOTR vs. water depth for FMC fine bubble tube
diffusers.
UJ
i-
o
CO
30
25
20
15
10
5
0
0
O 0.5 hp/!000 ft3
a i .0 hp/iooo ft3
A ! .5 hp/IOOO ft3
_L
10 15 20 25
WATER DEPTH (ft)
30
Figure D-8. SOTE vs. water depth for FMC fine bubble tube
diffusers.
141
-------
t_
-C
I
Q,
^
OJ
*i
OJ
o
«O
UJ
5
CO
6.0
5.0
4.0
3.0
2.0
1.0
n
^___^_^
- °~~~ "° ~~~°
fi pi «~ «
A — r
_ -^^^ -
~O 0.5 hp/IOOO ft3 _
n i .0 hp/iooo ft3
~ A 1.5 hp/IOOO ft3
1 1
3.0 2
JC.
0)
c_
2,0 "i
\
(M
o
en
! .0 2
f\
WATER DEPTH (ft)
Figure D-9. SWAE vs. water depth for FMC fine bubble tube
diffusers.
14Z
-------
APPENDIX E
INDIVIDUAL PERFORMANCE RESULTS FOR PENTECH JET AERATORS
A total of 18 acceptable tests were conducted on the Pentech jet
aeration system in this study. The results of these tests were
summarized tabularly in Tables 7 and 8 in Section 6 and are presented
graphically here in Figures E-l through E-9.
The effect of variations in airflow rate on delivered power
density is shown in Figure E-l for the various water depths. As
expected, an increase in airflow rate resulted in an increase in
delivered power density.
Figure E-2 shows the relationship between nominal power density
and delivered power density. The effect that is generally
demonstrated is that as power density increased, the differences
between nominal and delivered power densities increased. The
differences became larger with decreasing water depth.
Figure E-3 illustrates the relationship between delivered power
density and K\_&2Q- In this plot, the Ki_a2Q rate of increase is
initially high, then appears to decrease slightly with increasing
delivered power density. Also apparent is that increasing water depth
resulted in increasing K[_a2Q values.
SOTR is plotted against delivered power density in Figure E-4.
SOTR is expressed in both U.S. customary units (left vertical axis)
and SI units (right vertical axis). For the Pentech system, an
increase in delivered power density produced an increase in SOTR. The
rate of SOTR increase of this system was nonlinear at all water
depths. The nonlinearity was essentially the same for all depths and
was characterized by a higher rate of increase in SOTR values at low
delivered power densities. Also apparent in this graph is the
substantial effect of increasing water depth on SOTR. Increasing
water depth had a much smaller effect on K(_a20 (Figure E-3).
Figure E-5 is a plot of the relationship between SOTE and
delivered power density. The values of SOTE for each water depth are
clearly the highest at the lowest delivered power density level
tested. The trend of SOTE values for this system was a moderate
decrease with increasing delivered power density. Also evident in
143
-------
o
99
500
400
tf 300
cc
I 200
u.
i loo^
O i Oft DEPTH
D i 5 ft DEPTH
A 20ft DEPTH
O 2 5 ft DEPTH
200
150
100
50
o
«
w
0 0,5 1.0 1.5 2.0 2.5
DELIVERED POWER DENSITY(hp/IOOO ft3)
Figure E-l. Airflow rate vs. delivered power density for
Pentech jet aerators.
cc
u
1
o
UJ
cc
UJ
UJ
o
10
2.5
2.0
- 1.5
O
O
o
=; i.o
0.5
O i Oft DEPTH
D t 5 ft DEPTH
A 20ft DEPTH
O 25ft DEPTH
0 0.5 1.0 1.5 2.0
NOMINAL POWER DENSITY (hp/1000 ft3)
Figure E-2. Delivered power density vs. nominal power density
for Pentech jet aerators.
144
-------
o
CM
O
25
20
1 5
I 0
5
O 10ft DEPTH
n 1 5 ft DEPTH
A 20ft DEPTH
O 25ft DEPTH
'0 0.5 1.0 1.5 2.0 2.5
DELIVERED POWER DENSITY (hp/IOOO
Figure E-3. Ki_a20 vs. delivered power density for Pentech jet
aerators.
CVJ
O
O
CO
100
80
60
40
20
0
O 1 0 ft DEPTH
D ) 5 ft DEPTH
u- A 2 0 ft DEPTH
OESft DEPTH
0 0.5 1.0 i.5 2.0 2.5
DELIVERED POWER DENSITY (hp/IOOO ft3)
40
30
20
10
0
en
Figure E-4, SOTR vs. delivered power density for Pentech jet
aerators.
145
-------
UJ
(-
o
CO
50
40
30
20
10
O i 0 ft DEPTH
O ! 5ft DEPTH
A 20ft DEPTH
O 2 5 ft DEPTH
0-5 i.O 1.5 2.0 2.5
DELIVERED POWER DENSITY (hp/IOOO ft3)
Figure E-5. SOTE vs. delivered power density for Pentech jet
aerators.
5.0
4.0
s 3.0
CM
O
£ 2.0
\_/
UJ
I 1.0
O I Oft DEPTH
D I 5ft DEPTH
A 20ft DEPTH
O 2 5 ft DEPTH
0
0.5
.0
1.5
2.0
2.5
3.0
2.0
1.0
0
DELIVERED POWER DENSITY(hp/IOOO ft3)
Figure E-6. SWAE vs. delivered power density for Pentech jet
aerators.
-------
this graph is the existence of a relationship between SOTE and water
depth; an increase in water depth resulted in an improvement in SOTE.
SWAE vs. delivered power density Is shown for Pentech in Figure
E-6, SWAE is given in both U.S. customary units and SI units. For
this system, the highest SWAE values occurred at the middle delivered
power density. The trend of the data is such that any variation of
the delivered power density either above or below the middle value
caused a decrease in SWAE. Unlike the preceding two graphs,
increasing water depth did not necessarily result in increased values
of the dependent variable (vertical axis).. Increasing water depth
clearly produced changes in SWAE for this, system, however. The
highest values of SWAE occurred at the 7.6-m (25-ft) water depth.
figure E-7 illustrates the relationship between SOTR and test
tank water depth, with SQTR expressed tn both U.S. customary units and
SI units. The Pentech system exhibited an almost linear increase in
SOTR with increasing water depth. The highest SOTR values were
observed at the highest nominal power density.
SOTE vs. water depth is plotted in Figure E-8. Increasing SOTE
was observed with increasing water depth for this aeration system as
with each of the other six systems tested at multiple water depths.
For this system, all three power density curves indicate that the rate
of increase in SOTE dropped off slightly at the 7.6-m (25-ft) water
depth. In this graph, the highest values of SOTE were associated with
the lowest nominal power density.
This system's relationship of SWAE to water depth is shown in
Figure E-9. SWAE is expressed in both U.S. customary units and SI
units. SWAE generally increased with increasing water depth. Peak
SWAE performance for this system was noted at the 7.6-m (25-ft) water
depth. Variations in nominal power density appear to have
significantly affected the results, with the optimum SWAE occurring at
the middle nominal power density evaluated.
147
-------
CJ
O
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I
CL
X
CM
O
UJ
<
CO
5.0
4.0
3.0
2.0
I .0
O 0.5 hp/IOOO ft3
n i.o hp/iooo ft3
A 1.5 hp/!000 ft3
10 15 20
WATER DEPTH (ft)
25
3.0
2.0
.0
at
i_
*i
Figure E-9. SWAE vs. water depth for Pentech jet aerators
149
-------
APPENDIX F
INDIVIDUAL PERFORMANCE RESULTS FOR KENICS STATIC TUBE AERATORS
A total of 12 acceptable tests were conducted on the Kenics
static tube aeration system in this study. Test results for this
system were summarized tabularly in Tables 9 and 10 (Section 6) and
are shown graphically here in Figures F-l through F-9.
Figure F-l illustrates the effect that variations in airflow rate
have on delivered power density at the various water depths. As
expected, an increase in airflow rate produced an increase in
delivered power density.
The relationship between nominal power density and delivered
power density is shown in Figure F-2. As with the other systems, as
power density increased, discrepancies between nominal and delivered
power densities increased. The discrepancies became larger as water
depth decreased.
The relationship of delivered power density to K|_a2Q is plotted
in Figure F-3. K|_a2Q increased in a similar manner for curves
representing three of the four water depths. In these three cases,
the K|_a2Q rate of increase was high, then decreased slightly with
increasing delivered power density. Also apparent is that increasing
water depth generally resulted in increasing K|_a2Q values for the
Kenics static tube aerator.
Figure F-4 is a plot of SOTR vs. delivered power density. This
plot gives SOTR values in both U.S. customary units (left vertical
axis) and SI units (right vertical axis). An increase in the
delivered power density resultd in an increase in this system's SOTR.
The rate of increase in SOTR appears to have been almost linear at all
water depths. For curves representing three of the four water depths,
a slight nonlinearity was observed. This minor nonlinearity was
characterized by a higher rate of increase in SOTR values at low
delivered power densities. Also apparent is the significant effect of
increasing water depth on SOTR, an effect much greater than that noted
in K[_a2Q.
The relationship between SOTE and delivered power density is
shown graphically in Figure F-5. SOTE was unaffected by changes in
150
-------
/-\
<*-
o
to
UJ
_
DC
<
500
400
300
200
100
O i Oft DEPTH
D I 5 ft DEPTH
A 2 0 ft DEPTH
O 2 5 ft DEPTH
200
150
100
50
-------
o
s
-X.
25
20
I 5
I 0
5
O t 0 ft DEPTH
D I 5ft DEPTH
A EOft DEPTH
O 2 5ft DEPTH
0 0,5 1.0 1.5 2.0 2.5
DELIVERED POWER DENSITY (hp/1000 ff3)
Figure F-3. KifyQ vs« delivered power density for Kenics static
tube aerators.
120
!00
•"»
\ 80
eg
O
^ 60
a:
o
CO
40
20
O I 0 ft DEPTH
0 I 5 ft DEPTH
A 20 ft DEPTH
O2 5 ft DEPTH
50
40
30
20
10
'0 0.5 1.0 1.5 2.0 2.5°
DELIVERED POWER DENSITY (hp/IOOO ft3)
Figure F-4. SOTR vs. delivered power density for Kenics static
tube aerators.
152
-------
8
LU
1-
O
03
£ Q
20
1 5
10
5
n
0 10 ft
n i 5ft
A 20ft
0— — v-—~ ^ _^^ O 2 5 f t
A.
.Ft t~
o_
0 GU~' — - — o
DEPTH
DEPTH
DEPTH
DEPTH
1
0 0.5 1.0 1.5 2.0 2.5
DELIVERED POWER DENSITY (hp/IOOO ft3)
Figure F-5. SOTE vs. delivered power density for Kenics static
tube aerators.
5.0
4.0
i 3.0
C\J
O
ja
^f
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CO
2.0
1.0
O 1 Oft DEPTH
D I 5 ft DEPTH
h- A 20ft DEPTH
O 25ft DEPTH
3.0
2.0
1.0
^£
01
OJ
O
O)
"0 0.5 1.0 1,5 2.0 2.5 w
DELIVERED POWER DENS!TY(hp/1000 ft3)
Figure F-6. SWAE vs. delivered power density for Kenics static
tube aerators.
153
-------
delivered power density. An increase in water depth resulted in
higher SOTE VALUES.
SWAE is plotted against delivered power density in Figure F-6,
with SWAE provided in both U.S. customary units and SI units. For
this coarse bubble system, the highest SWAE values occurred at the
lowest delivered power density except at the 6.1-m (20-ft) water
depth. SWAE generally decreased with increasing values of delivered
power density. Increasing water depth did not always result in
increased SWAE values, however. The effect of increasing water depth
on this system's SWAE does appear to have been significant, however,
with the highest values of SWAE observed at the 7.6-ifr (25-ft) water
depth.
The relationship of 50TR to test tank water depth is illustrated
in Figure F-7, with SOTR given in both U.S. customary units and SI
units. This system exhibited a somewhat linear increase in SOTR with
increasing water depth, with the highest SOTR observed at the highet
nominal power density.
Figure F-8 is a plot of SOTE vs. test tank water depth.
Increasing SOTE with increasing water depth was noted for this system
as with each of the other six aeration systems tested at multiple
water depths. For this system, the data indicate a somewhat linear
relationship between SOTE and depth- The various SOTE values
representing different noairtal power densities are tightly clustered.
In this graph, the highest SOTE values do not appear to be associated
with any particular nominal power density.
This system's relationship of SWAE to water depth is shown In
Figure F-9. SWAE is expressed in both U.S. customary units and SI
units. The data indicate that SWAE tended to improve with increasing
water depth. Peak values of SWAE occurred at the 7.6-m (25-ft) water
depth. Significant variations in SWAE occurred with changes in
nominal power density; however, the cause of these changes was not
evident. Although the highest nominal power density generally
produced the lowest SWAE values, it is not clear which of the other
two power densities represents better performance.
154
-------
X
CJ
O
CC
O
CO
100
90
80
70
60
50
40
30
20
10
a
O 0,5 hp/!000 ft3
O 1.0 hp/!000 ft3
A i .5 hp/IOOO
ft
5 10 15 20
WATER DEPTH (ft)
Figure F-7. SOTR vs. water depth for Kertlcs static
tube aerators.
25
40
30
20
0
0
O
C/3
25
20
15
JO
5
0
0
O0.5 hp/iOQO ft3
a i .0 hp/iooo ft3
A 1,5 hp/ 1000 ft3
10 15 20
WATER DEPTH (ft)
25
Figure F-8. SOTE vs. water depth for Kenics static tube
aerators.
155
-------
5.0
i 4,0
03
"I 3.0
o
£ 2.0
\_^
Ld
g 1.0
CO
a
O0.5 hp/1000 ft3
D I .0 hp/1000 ft3
— A I .5 hp 1000 ft3
0
5 10 15 20
WATER DEPTH (ft)
3.0
2.0
s
V
i .0 °
25
Figure F-9. SWAE vs. water depth for Kenics static tube
aerators.
156
-------
APPENDIX 6
INDIVIDUAL PERFORMANCE RESULTS FOR BAUER VARIABLE ORIFICE OIFFUSERS
A total of 14 acceptable tests were conducted on the Bauer
variable orifice diffusion system in this study. The results of these
tests were summarized tabularly in Tables 11 and 12 in Section 6 and
are presented graphically here in Figures G-l through G-9.
The effect of variations in airflow rate on delivered power
density is shown in Figure G-l for the various water depths. As
expected, an increase in airflow rate resulted in an increase in
delivered power density.
Figure G-2 shows the relationship between nominal power density
and delivered power density. The effect that is generally
demonstrated is that as power density increased, the differences
between nominal and delivered power densities increased. The
differences became larger with decreasing water depth.
Figure 6-3 illustrates the relationship between delivered power
density and KLSJO- As shown in this plot, K|_a20 increased almost
linearly for the various water depths. Also apparent is that
increasing water depth resulted in increasing K|_a2Q values.
SOTR is plotted against delivered power density in Figure G-4.
SOTR is expressed in both U.S. customary units (left vertical axis)
and SI units (right vertical axis). For the Bauer system, an increase
in delivered power density produced an increase in SOTR. The rate of
increase in SOTR for this system appears to have been almost linear
for all water depths. Also apparent is the considerable effect of
increasing water depth on SOTR. Increasing water depth had a much
smaller effect on K|_a2Q (Figure G-3).
Figure G-5 is a plot of the relationship between SOTE and
delivered power density. SOTE increased slightly with increasing
delivered power density at each water depth. Also evident is that an
increase in water depth was accompanied by an improvement in SOTE,
SWAE vs. delivered power density is shown for Bauer in Figure
G-6. SWAE is given in both U.S. customary units and SI units. For
this system, SWAE was clearly affected by water depth, increasing with
157
-------
500
400
300
<
o:
g 200
100
O t 0 ft DEPTH
D I 5 ft DEPTH
ASQft DEPTH
O25ft DEPTH
200
150
100
50
'0 0.5 1.0 1.5 2.0 2.5
DELIVERED POWER DENSITY(hp/IOOO ft3)
u
03
to
Figure 6-1. Airflow rate vs. delivered power density for Bauer
variable orifice diffusers.
tz 10
ur
1§
o x-
LU O.
a £.
UJ
UJ
0
2.5
2,0
1.5
1.0
0.5
0
O I 0 ft DEPTH
D ! 5 ft DEPTH
A 20ft DEPTH
O 25ft DEPTH
0 0.5 1.0 1.5
NOMINAL POWER DENSITY (hp/IOOO
2.0
Figure G-2. Delivered power density vs. nominal power density
for Bauer variable orifice diffusers.
153
-------
o
CJ
o
25
20
I 5
I 0
5
0
O 1 0 ft DEPTH
D I 5 ft DEPTH
A 20ft DEPTH
O 25ft DEPTH
0 0.5 1.0- 1.5 2.0 2.5
DELIVERED POWER DENSITY(hp/IOOO ff3)
Figure G-3. K.apn vs- delivered power density for Bauer
variable orifice diffusers.
x-»
t_
X
O
o
c/3
! 00
80
60
40
20
Q
O ! Oft DEPTH
O ] 5 ft DEPTH
A 2 0 ft DEPTH
O25ft DEPTH
40
30
20
10
0 0.5 1,0 1.5 2.0 2.5
DELIVERED POWER DENSITY (hp/IOOO ft3)
Figure G-4. SOTR vs. delivered power density for Bauer variable
orifice diffusers.
159'
-------
UJ
20
15
8 10
O I 0 ft DEPTH
D I 5 ft DEPTH
A 20ft DEPTH
O 25ft DEPTH
O-
-O-
-oo
'0 0.5 i.O 1.5 2.0 2.5
DELIVERED POWER DENSITY (hp/IOOO ft3)
Figure 6-5. SOTE vs. delivered power density for Bauer variable
orifice diffusers.
CJ
O
k 4-0
"i 3.0
2.0
OJ
3 1.0
CO
O 1 0 ft DEPTH
O I 5 ft DEPTH
A 20ft DEPTH
O25ft DEPTH
3.0
2.0
I .0
a
OJ
0.5 1.0 1.5 2.0 2.5
DELIVERED POWER DENS!TY(hp/IOOO ft3)
Figure 6-6. SWAE vs. delivered power density for Bauer variable
orifice diffusers.
160
-------
each increase in depth. For the 4.6-, 6»1-, and 7.6-m (15-, 20-, and
25-ft) water depths, SWAE was virtually unaffected by changes in
delivered power density. At the 3.0-m (10-ft) water depth, SWAE
decreased with increasing delivered power density.
Figure G-7 illustrates the relationship between SOTR and test
tank water depth, with SOTR expressed in both U.S. customary units and
SI units. The Bauer system exhibited an almost linear increase in
SOTR with increasing water depth. The highest SOTR values were
observed at the highest nominal power density.
SOTE vs. water depth is plotted in Figure G-8. Increasing SOTE
was observed with increasing water depth for this aeration system as
with each of the other six systems tested at multiple water depths.
For this system, the data indicate a linear relationship between SOTE
and water depth at all three nominal power densities. The highest
values of SOTE were associated with the highest nominal power density.
This system's relationship of SWAE to water depth is shown in
Figure G-9. SWAE is expressed in both U.S. customary units and SI
units. SWAE generally increased with increasing water depth, although
not at a rapid rate. Peak values of SWAE occurred at the 7.6-m
(25-ft) water depth. At three of the four water depths, SWAE appears
to have been unaffected by changes in nominal power density.
161
-------
100
90
80
70
60
£ 50
X
OJ
o
O
OT
40
30
20
10
O 0,5 hp/1000 ft3
D i .0 hp/IOOO ft3
A 1 ,5 hp/IOOO ft3
0
20
25
40
30
20
10
0
WATER DEPTH Cft)
Figure G-7. SOTR vs. water depth for Bauer variable orifice
diffusers.
QJ
O
CO
25
20
15
10
5
o;
O0.5 hp/IOOO ft3
D t .0 hp/IOOO ft3
A 1.5 hp/IOOO ft3
10 15 20
WATER DEPTH (ft)
25
Figure G-8. SOTE vs. water depth for Bauer variable orifice
diffusers.
162
-------
c_
.e
1
Q.
r-
-------
APPENDIX H
INDIVIDUAL PERFORMANCE RESULTS FOR SANITAIRE COARSE BUBBLE DIFFUSERS
A total of 12 acceptable tests were conducted on the Sanitaire
coarse bubble diffusion system in this study. Test results for this
system were summarized tabularly in Tables 13 and 14 (Section 6) and
are shown graphically here in Figures H-l through H-9.
Figure H-l illustrates the effect that variations in airflow rate
have on delivered power density at the various water depths. As
expected, an increase in airflow rate produced an increase in
delivered power density.
The relationships between nominal power density and delivered
power density is shown in Figure H-2. As with the other systems, as
power density increased, discrepancies between nominal and delivered
power densities increased. The discrepancies became larger as water
depth decreased.
The relationship of delivered power density to K[_a20 ^s plotted
in Figure H-3. ^i^2Q increased almost linearly for all four water
depths with increasing delivered power density. Also apparent is that
increasing water depth was not a controlling influence on the relative
positions of the KI^O curves.
Figure F-4 is a plot of SOTR vs. delivered power density. This
plot gives the SOTR in both U.S. customary units (left vertical axis)
and SI (right vertical axis). An increase in the delivered power
density resulted in an increase in this system's SOTR. The rate of
increase for the SOTR of this system appears to have been essentially
linear for all water depths. Also apparent in this graph is the
significant effect of increasing water depth on SOTR, particularly
separating the two higher from the two lower water depths. This
effect was much greater than that observed with
The relationship between SOTE and delivered power density is
shown graphically in Figure H-5. SOTE values were the lowest at the
lowest levels of delivered power density, and increased steadily with
increasing delivered power density. An increase in water depth also
resulted in higher SOTE values.
164
-------
u
CO
UJ
500
400
300
I 2°°
100
0 I Oft DEPTH
0 I 5 ft DEPTH
A 20ft DEPTH
O 25ft DEPTH
200
50 Q
100
50
'0 0.5 1.0 1.5 2.0 2.5
DELIVERED POWER DENSITY(hp/IO00 ft3)
0)
CO
X
Figure H-l. Airflow rate vs. delivered power density for Sanitaire
coarse bubble diffusers.
£
CO
10
0
UJ
o:
UJ
UJ
o
2.5
2.0
1.5
1.0
0.5
0
OlOft DEPTH
D 1 5 ft DEPTH
A 20ft DEPTH
O25ft DEPTH
0 0.5 1.0 1.5 2.0
NOMINAL POWER DENSITY (hp/l000 ft3)
Figure H-2. Delivered power density vs. nominal power density
for Sanitaire coarse bubble diffusers.
165
-------
o
CM
O
25
20
I 5
10
5
O I Oft DEPTH
n I 5 ft DEPTH
A 20ft DEPTH
O 25ft DEPTH
0.5 1.0 1.5 2.0 2.5
DELIVERED POWER DENSITY (hp/IOOO
Figure H-3. Ki*2Q vs. delivered power density for Sanitaire
coarse bubble diffusers.
00
80
£ 60
o
CO
40
20
0,
O I 0 ft DEPTH
n 1 5 ft DEPTH
A 20ft DEPTH
O 2 5 ft DEPTH
0 0.5 1.0 1.5 2.0 2.5
DELIVERED POWER DENSITY (hp/IOOO ft3)
40
30
20
10
0
V.
en
Figure H-4. SOTR vs. delivered power density for Sanitaire
coarse bubble diffusers.
166
-------
LJ
O
CO
25
20
I 5
10
5
O 1 0 ft DEPTH
D ! 5ft DEPTH
A 2 0 ft DEPTH
O 2 5 ft DEPTI
"0 0.5 t.O 1.5 2.0 2.5
DELIVERED POWER DENSITY (hp/IOOO ft3)
Figure H-5. SOTE vs. delivered power density for Sam'taire
coarse bubble diffusers.
t_
"f
"i
OJ
O
-Q
LJ
5
CO
a
4
3
2
1.
.0
0
0
0
n
—
Ar- ^ _
— -0— " " "^ "
r"t r^i
O *^^ ~ — — i •
~^~~ ' Q
O 10 ft DEPTH ~
n 1 5 ft DEPTH
~~ A 20ft DEPTH
<> 25ft DEPTH
! I 1 1 1
3.0
2.0
0
0
DELIVERED POWER DENSITY{hp/IOOO ft3)
Figure H-6. SWAE vs. delivered power density for Sanitaire
coarse bubble diffusers.
01
"i
X.
CJ
O
167
-------
SWAE is platted against delivered power density in Figure H-6,
with SWAE provided in both U.S. customary units and SI units- For
this coarse bubble system, SWAE values increased slightly with
increasing power density for the two higher water depths and decreased
slightly with increasing power density at the two Tower water depths.
The effect of increased water depth on this system appears to have had
an influence on SWAE; however, it should be noted that the highest
values of SWAE occurred at the 6.1 (20), not 7.6-m (25-ft), water
depth.
The relationship of SQTR test tank water depth is illustrated in
Figure H-7, with SOTR given in both U.S. customary units and SI units.
Although increasing water depth definitely influenced the magnitude of
the SOTR values, diffuser configuration also appears to have played a
role in determining SOTR for this system. A different configuration
was used for the 3.0- and 6.1-m (10- and 20-ft) water depths than for
the 4.6- and 7.6-m (15-and 25-ft) water depths. Rather than
connecting all points in succession at a given nominal power density,
points of like configuration have been connected because of the
apparent relationship that existed between SOTR and configuration for
the Sanitaire diffuser. The highest SQTR values were observed at the
highest nominal power density at each water depth.
Figure H-8 is a plot of SOTE vs. test tank water depth.
Increasing SOTE with increasing water depth was noted for this system
as with each of the other six aeration systems tested at multiple
water depths. As in preceding figure, however, diffuser configuration
appears to have strongly influenced the data observed at a given
nominal power density. For this system, the highest values of SOTE
were associated with the highest nominal power density.
This system's relationship of SWAE to water depth is shown in
Figure H-9. SWAE is expressed in both U.S. customary units and SI
units. Again, the apparent influence of diffuser configuration is
evident. Increasing water depth generally produced increasing SWAE.
However, peak SWAE values did not occur at 7.6-m (25-ft) water depth,
but at 6.1-m (20-ft) water depth. The variation in nominal power
density at each depth does not appear to have significantly affected
SWAE and it is not clear at which nominal power density peak SWAE
performance occurred.
168
-------
CM
O
-0
O
(0
100
90
80
70
60
50
40
30
20
10
O 0.5 hp/!000 ft3
D 1.0 hp/IOOO
A I .5 hp/IOOO
ft.3
ft
10
20
WATER DEPTH (ft)
25
40
30
20
10
0
Figure H-7. SOTR vs. water depth for Sanitaire coarse bubble
diffusers.
en
JC
\*r
UJ
I-
o
CO
25
20
I 5
10
5
0
O 0 5 hp/1000 ft3
D t.O hp/IOOO ft3
A i .5 hp/IOOO ft3
10 15 20
WATER DEPTH (ft)
25
Figure H-8. SOTE vs. water depth for Sanitaire coarse bubble
diffusers.
169
-------
5.0
<~N
f 4.0
j=
09
| 3.0
CM
2 z.o
UJ
CO
I .0
O 0.5 hp/1000ft3
n 1,0 hp/IOOO ft3
A 1.5 hp/IOOO ft3
10 15 20
WATER DEPTH (ft)
3.0
2.0
CM
-° 5*
v-/
25
0
Figure H-9. SWAE vs. water depth for Sanitaire coarse bubble
diffusers.
170
-------
APPENDIX I
INDIVIDUAL PERFORMANCE RESULTS FOR ENVIREX COARSE BUBBLE DIFFUSERS
A total of 15 acceptable tests were conducted on the Envirex
coarse bubble diffusion system in this study. The results of these
tests were summarized tabularly in Tables 15 and 16 in Section 6 and
are presented graphically here in Figures 1-1 through 1-9.
The effect of variations in airflow rate on delivered power
density is shown in Figure 1-1 for the various water depths. As
expected, an increase in airflow rate resulted in an increase in
delivered power density.
Figure 1-2 shows the relationship between nominal power density
and delivered power density. The effect that is generally
demonstrated is that as power density increased, the differences
between nominal and delivered power densities increased. The
differences became larger as water depth decreased.
Figure 1-3 illustrates the relationship between delivered power
density and K|_a2Q. As shown in this plot, K[_a20 increased linearly
for the 5.1-m (20-ft) water depth. For the other three depths, the
K|_a20 fate of increase was high initially, then decreased slightly
with increasing power density. Also apparent is that increasing
water depth resulted in increasing KI^Q values.
SOTR is plotted against delivered power density in Figure 1-4.
SOTR is expressed in both U.S. customary units (left vertical axis)
and SI units (right vertical axis). For the Envirex system, an
increase in delivered power density produced an increase in SOTR. The
rate of increase in SOTR for this system appears to have been almost
linear for all water depths. Also apparent is the substantial effect
of increasing water depth on SOTR. Increasing water depth had a much
smaller effect on Kj_a20 (Figure 1-3).
Figure 1-5 is a plot of the relationship between SOTE and
delivered power density. The lowest SOTE values corresponded with the
lowest delivered power density level at each water depth. For three
of the four water depths, SOTE increased almost linearly with
increasing levels of delivered power density. At the 7.6-m (25-ft)
water depth, however, the highest SOTE value occurred at the middle
delivered power density tested. Also evident is that an increase in
water depth was accompanied by a consistent improvement in SOTE.
171
-------
o
tr
500
400
300
200
100
O 1 0 ft DEPTH
D 1 5 ft DEPTH
A 20ft DEPTH
O25ft DEPTH
0 0.5 1.0 1.5 2.0 2.5
DELIVERED POWER DENSITY(hp/l000 ft3)
200
!50
!00
50
0
Figure 1-1. Airflow rate vs. delivered power density for
Envirex coarse bubble diffusers.
o
d>
to
OC 10
uc
i§
Q V
Uj a.
OL £
UJ
UJ
O
2.5
2.0
1.5
1.0
0.5
O.Q
O I 0 ft DEPTH
D ! 5 ft DEPTH
A 20ft DEPTH
O 25ft DEPTH
D.O 0.5 i.O 1.5 2.0
NOMINAL POWER DENSITY (hp/l000 ft3)
Figure 1-2. Delivered power density vs. nominal power density
for Envirex coarse bubble diffusers.
172
-------
o
cu
o
25
20
I 5
1 0
5
Oj
O I Oft DEPTH
O I 5ft DEPTH
A 20ft DEPTH
O 25ft DEPTH
0 0.5 1.0 1.5 2.0 2.5
DELIVERED POWER DENSITY (hp/!000 ft3)
Figure 1-3. K|_a2Q vs. delivered power density for Envirex
coarse bubble diffusers.
/»••»
E.
.C
\
O
J3
~
or
o
CO
100
80
60
40
20
O I Oft DEPTH
D 1 5 ft DEPTH
A 2 Oft DEPTH
O 2 5 ft DEPTH
'0 0.5 LO 1.5 2.0 2.5
DELIVERED POWER DENSITY(hp/IOOO ft3)
40
30
20
10
0
01
Figure 1-4. SOTR vs. delivered power density for Envirex
coarse bubble diffusers.
173
-------
u
o
en
25
20
15
10
5
0
O I Oft DEPTH
D I 5ft DEPTH
A 20ft DEPTH
O 2 5 ft DEPTH
0 0.5 1.0 1.5 2.0 2.5
DELIVERED POWER DENSITY {hp/IOOO ft3)
Figure 1-5. SOTE vs. delivered power density for Envirex
coarse bubble diffusers.
c_
-C
1
Q.
C_
"i
N.
A 1
LvJ
O
—
LJ
s
Cfl
O.
4.
3.
2.
1.
u
0
0
0
0
n
O 1 0 ft DEPTH
a 1 5ft DEPTH
- A 20ft DEPTH
O 25ft DEPTH/v
fr-*~**~*~^^~~~~~~~~~~~~~~-& ~
_
^_ D- - — _ — __Q
- 0
—
! 1 ! 1 1
=13.0
-2.0
-I .0
'0 0.5 1.0 1.5 2.0 2.5
DELIVERED POWER DENSITY(hp/IOOO ft3)
=£
N.
Figure 1-6. SWAE vs. delivered power density for Envirex
coarse bubble diffusers.
174
-------
SWAE vs. delivered power density is shown for Envirex in Figure
1-6. SWAE is given in both U.S. customary units and SI units. For
this system, SWAE was virtually unaffected by changes in delivered
power density except at the 7.6-m (25-ft) water depth. SWAE values
increased with each increase in water depth.
Figure 1-7 illustrates the relationship between SOTR and test
tank water depth, with SOTR expressed in both U.S. customary units and
SI units. For the Envirex system, two of the three nominal power
density curves exhibited an increasing rate of increase in SOTR with
increasing water depth, while the third curve indicated a constant
rate of increase. The highest SOTR values were observed at the
highest nominal power density.
SOTE vs. water depth is plotted in Figure 1-8. Increasing SOTE
was observed with increasing water depth for this aeration system as
with each of the other six systems tested at multiple water depths.
For this system, the data indicate a mostly linear relationship
between SOTE and water depth. The highest values of SOTE generally
corresponded with the highest nominal power density.
This system's relationship of SWAE to water depth is shown in
Figure 1-9. SWAE is expressed in both U.S. customary units and SI
units. A trend of increasing SWAE is evident with increasing water
depth. Peak values of SWAE occurred at the 7.6-m (25-ft) water depth.
The nominal power density values are clustered closely together at
three of the four water depths, indicating this system's insensitivity
to variations in power density.
175
-------
100
90
80
/•>
$ 70
Sf 60
6 50
oe 40
30
20
10
O
CO
O 0.5 hp/IOOO ft3
D I .0 hp/IOOO ft3
A 1.5 hp/IOOO ft3
ID
10 15 20
WATER DEPTH (ft)
25
40
30
20
10
0
x
Figure 1-7. SOTR vs. water depth for Envirex coarse bubble diffusers,
LL)
O
25
20
15
10
° 0.5 hp/IOOO ft3
D 1.0 hp/IOOO ft3
A 1.5 hp/IOOO ft3
'0
10 15 20
WATER DEPTH Cft)
25
Figure 1-8. SOTE vs. water depth for Envirex coarse bubble diffusers.
176
-------
c-
I
o.
"i
X
OJ
o
LU
s
CO
J .
4.
.
2.
1.
u
0
0
0
n
O 0,5 hp/IOOO ft3
_ O t .0 hp/IOOO ft3
A 1.5 hp/IOOO ft3
^^T^^^
Q-— "^""^^^"^^"'^
/^*~*~"^~"^
—
—
1 ! ! 1 1
3.0
2.0
5
CVJ
TO
WATER DEPTH (ft)
Figure 1-9. SWAE vs. water depth for Envirex coarse bubble diffusers.
177
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APPENDIX J
INDIVIDUAL PERFORMANCE RESULTS FOR FMC COARSE BUBBLE DIFFUSERS
A total of three acceptable tests were run on the FMC coarse
bubble diffusion system (Deflectofuser) in this study. Test results
for this system were summarized tabularly in Tables 17 and 18 (Section
6) and are shown graphically here in Figures J-l through J-6.
Figures J-l illustrates the effect that variations in airflow
rate have on delivered power density. As expected, an increase in
airflow rate produced an increase in delivered power density.
The relationship between nominal power density and delivered
power density is shown in Figure J-2. The effect that is generally
demonstrated is that as power density increased, the discrepancy
between nominal and delivered power densities also increased.
The relationship of delivered power density to K[_a20 is plotted
in Figure J-3. KLa20 increased linearly with increasing delivered
power density.
Figure J-4 is a plot of SOTR vs. delivered power density. This
plot gives SOTR values in both U.S. customary units (left vertical
axis) and SI units (right vertical axis). An increase in the
delivered power density resulted in an increase in this system's SOTR.
The rate of increase was approximately constant for the water depth
tested.
The relationship between SOTE and delivered power density is
graphed in Figure J-5. SOTE increased with each increase in delivered
power density, but only at a very moderate rate.
SWAE is plotted against delivered power density in Figure J-6,
with SWAE provided in both U.S. customary units and SI units. For
this coarse bubble system, although the highest SWAE value occurred at
the lowest delivered power density, the curve indicates that changes
in delivered power density had little impact on SWAE.
178
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500
2 400
o
to
s^
£ 300
or
5 200
o
_i
Lt_
S 100
O 15 ft DEPTH
0 0.5 1.0 1.5 2,0 2.5
DELIVERED POWER DENSITY(hp/IOOO ft3)
200
150
100
50
0
o
CD
CO
Figure J-l. Airflow rate vs. delivered power density for FMC
coarse bubble diffusers.
K>
§
Q N.
UJ O.
o: £
UJ
LLl
O
2.5
2.0
1.5
1.0
0.5
D 15 ft DEPTH
0 0.5 1.0 i .5
NOMINAL POWER DENSITY (hp/IOOO
2.0
Figure J-2. Delivered power density vs. nominal power density
for FMC coarse bubble diffusers.
179
-------
o
w
o
25
20
I 5
10
5
(5ft DEPTH
t> 0.5 1.0 I-5 2.0 2.5
DEUVERED POWER DENSITY (hp/1000
Figure J-3. K|_a2Q vs. delivered power density for FMC coarse
bubble diffusers.
O
J3
O
CO
50
40
30
20
I 0
O 15 ft DEPTH
20
0
0 0.5 1.0 1.5 2.0 2.5
DELIVERED POWER DENSITY (hp/IOOO ft3)
0
cr>
Figure J-4. SOTR vs. delivered power density for FMC coarse
bubble diffusers.
180
-------
u
o
CO
15
D 15 ft DEPTH
'0 0.5 LO 1.5 2.0 2.5
DELIVERED POWER DENSITY (hp/IOOO ft3)
Figure J-5. SOTE vs. delivered power density for FMC coarse
bubble diffusers.
5.0
f 4.0
a.
i 3.0
CJ
o
^
\s
LU
CO
2.0
1 .0
0
O 15 ft DEPTH
3.0
2.0 -*
OJ
1.0
0 0.5 1.0 1.5 2.0
DELIVERED POWER DENSlTY(hp/IOOO ft3)
OJ
O
Figure J-6. SWAE vs. delivered power density for FMC coarse
bubble diffusers.
181
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