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Scholars' Mine Scholars' Mine
Masters Theses Student Theses and Dissertations
1966
Some effects of selected biodegradable detergents on the Some effects of selected biodegradable detergents on the
aeration of water and activated sludge aeration of water and activated sludge
Donald Ernest Modesitt
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Recommended Citation Recommended Citation Modesitt, Donald Ernest, "Some effects of selected biodegradable detergents on the aeration of water and activated sludge" (1966). Masters Theses. 5770. https://scholarsmine.mst.edu/masters_theses/5770
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SOME EFFECTS OF SELECTED BIODEGRADABLE DETERGENTS ON THE AERATION OF WATER AND ACTIVATED SLUDGE
BY
DONALD ERNEST MODESITT
A
THESIS
submitted to the faculty of
THE UNIVERSITY OF MISSOURI AT ROLLA
in partial fulfillment of the requirements for the
Degree of
MASTER OF SCIENCE IN CIVIL ENGINEERING
Rolla, Missouri
1966
Approved by
'•
ABSTRACT
The purpose of this study was to determine what effects the
presence of selected biodegradable detergents have on the aeration of
water and the activated sludge process for aerobic wastewater treat
ment. The detergents studied were LAS #1, Alfol, and Nalkylene. It
was of particular interest to determine if these detergents decreased
the oxygen absorptive capacities of water and wastewater. If detri
mental effects were produced by the detergents it was then desired to
determine if these effects were serious enough to create problems with
aerobic wastewater treatment and aeration in receiving bodies of
water.
A two liter volume of the liquids were aerated by bubble aeration
at rates of 300 and 600 ml/min/1. The effects produced by the presence
of 2, 5, and 10 mg/1 of each detergent on the rate of oxygen transfer
and oxygen saturation concentration of distilled water, tap water, and
activated sludge were compared with the effects exhibited by similar
aeration of the same volume of liquid without the presence of detergent.
It was found that each detergent did not produce the same degree
of effect in the different liquids. It was found to be possible for a
detergent to decrease the oxygen transfer rate and oxygen absorptive
capacity in distilled water and tap water yet increase the oxygen
transfer rate and oxygen absorptive capacity of the activated sludge
over that which existed when the detergent was not present.
The degree of effect produced by the detergents was not always
proportional to the concentration of detergent. The rate of aeration
was noted to be capable of causing a change in the effects produced by
the detergents.
ACKNOWLEDGMENTS
The author expresses his appreciation for the enthusiastic
assistance of Dr. Don F. Kincannon throughout the study and in the
preparation of this thesis. He is also thankful to Professor J. Kent
Roberts for his helpful suggestions.
The author wishes particularly to acknowledge his wife for her
patience, encouragement, and helpfulness while this thesis was in
preparation.
Acknowledgment is also made to Mr. Theodore E. Brenner, Research
Director of the Soap and Detergent Association, and Dr. James C. Kirk
of the Continental Oil Company for the detergent samples and
information they courteously provided.
TABLE OF CONTENTS
PAGE
LIST OF FIGURES • • . • . • . • • • • . • • • • • • . • . • . • • . . . • . • . • • • . • • • . • . • • . . • . . . . i i
I.
II.
III.
IV.
v.
VI.
VII.
VIII.
INTRODUCTION .•••••••••.•.••.•.••••.•••..••.•.••....•••••••.
REVIE'W' OF LITERATURE .•••••.••..••.•.•••••.••••.•••••.•••••.
THEORETICAL CONCEPTS ••••••..•••..••••..•••••••••.•••.••••••
MATERIALS AND METHODS .•••••• A. B.
Materials •••••• Methods .•••••••
. ...... .
PRESENTATION OF RESULTS •••• A. Distilled Water System. B. Tap Water System .•••••• C. Activated Sludge System •••••
DISCUSSION OF RESULTS .••••••• A. Distilled Water System ••• B. Tap Water System •••••.•••••••• C. Activated Sludge System ••••••• D. Overall Oxygen Transfer Coefficient, ~a
CONCLUSIONS ••••••••••••••.•••..•..••..••••.••.•••••••••••••
REC~NDATI ONS .•••••••••••••••••••••.••••••••••.••••••••••
1
4
8
14 14 16
23 23 28 36
48 48 49 50 51
56
58
BIBLIOO.RAPIIY.... • • • . • • • • • • • • • • . • • • • • • • . • . • • • • • • • . • • • • • . • • • . 59
VITA....................................................... 61
ii
LIST OF FIGURES
FIGURE PAGE
1. Concentration of Oxygen in Water vs. Time •••••••••••••.••••. 9
2. Absorption of Oxygen in Water ••••••••••••••••••••••••••••••• 10
3. Experimental Equipment .••.••••.••..•.....•••••.•.•••....•... 17
4. Activated Sludge Units .•••.•••.••••••...•.••.••..••••••••••. 20
5. Optical Density vs. Biological Sbl{da ::: •••••••••••••••••••••• 21
6. Dissolved Oxygen Deficit vs. Time for 300 ml/min/1 Aeration of Distilled Water Containing LAS #1 •••••••••.••••• 25
7. Dissolved Oxygen Deficit vs. Time for 300 ml/min/1 Aeration of Distilled Water Containing Alfol •••••••••••••••• 26
8. Dissolved Oxygen Deficit vs. Time for 300 ml/min/1 Aeration of Distilled Water Containing Nalkylene •••••••••••• 27
9. Dissolved Oxygen Deficit vs. Time for 600 ml/min/1 Aeration of Distilled Water Containing LAS #1 •••••.••••••••• 29
10. Dissolved Oxygen Deficit vs. Time for 600 ml/min/1 Aeration of Distilled Water Containing Alfol .••••••••••••••. 30
11. Dissolved Oxygen Deficit vs. Time for 600 ml/mintl Aeration of Distilled Water Containing Nalkylene .••••••••••• 31
12. Dissolved Oxygen Deficit vs. Time for 300 ml/min/1 Aeration of Tap Water Containing LAS #1 .•••••••••••••••••••• 33
13. Dissolved Oxygen Deficit vs. Time for 300 ml/min/1 Aeration of Tap Water Containing Alfol •••••••••••••••••••••• 34
14. Dissolved Oxygen Deficit vs. Time for 300 ml/min/1 Aeration of Tap Water Containing Nalkylene •••••••••••••••••• 35
15. Dissolved Oxygen Deficit vs. Time for 600 ml/min/1 Aeration of Tap Water Containing LAS #1 •••••••••••••••.•.•.. 37
16. Dissolved Oxygen Deficit vs. Time for 600 ml/min/1 Aeration of Tap Water Containing Alfol .••••••••••••••••••••• 38
17. Dissolved Oxygen Deficit vs. Time for 600 ml/min/1 Aeration of Tap Water Containing Nalkylene •••••••••••••••••• 39
18. Dissolved Oxygen Deficit vs. Time for 300 ml/min/1 Aeration of Activated Sludge Containing LAS #1 .••••••••••••• 42
iii
LIST OF FIGURES (Continued)
FIGURE PAGE
19. Dissolved Oxygen Deficit vs. Time for 600 ml/min/1 Aeration of Activated Sludge Containing LAS #1 •••••••••••••• 43
20. Dissolved Oxygen Deficit vs. Time for 300 ml/min/1 Aeration of Activated Sludge Containing Alfol ••••••••••••••• 44
21. Dissolved Oxygen Deficit vs. Time for 600 ml/min/1 Aeration of Activated Sludge Containing Alfol ••••••••••••••• 45
22. Dissolved Oxygen Deficit vs. Time for 300 ml/min/1 Aeration of Activated Sludge Containing Nalkylene .•••••••••• 46
23. Dissolved Oxygen Deficit vs. Time for 600 ml/min/1 Aeration of Activated Sludge Containing Nalkylene .•••••••••• 47
24. ~a vs. Detergent Concentration in Distilled Water ••.••••••• 53
25. ~a vs. Detergent Concentration in Tap Water ...•...•.•...... 54
26. ~a vs. Detergent Concentration in Activated Sludge ••••••••• 55
I • INTRODUCTION
With the increase in water reuse and increasing quantity of
synthetic detergents used for residential, commercial, and industrial
purposes in recent years it should have been apparent that unless the
detergents were removed in waste treatment processes, degraded in the
receiving bodies of water, or removed in water treatment facilities
that an increasing concentration of these detergents would result in
taste, odor, and foaming problems. Anticipation of such problems did
occur to many and at least one synthetic detergent manufactur~r started
formulating plans for a biodegradable synthetic detergent as early as
1952.
In the late 1950's and into 1965 several instances of taste,
odor, and foaming problems associated with the "hard" or low
biodegradable detergents were brought to the public's attention.
Likely there were numerous other unreported occasions when these
problems caused concern at the local level. One of the more notable
cases in point occurred in the fall and winter of 1956-57 at Chanute,
Kansas when the climatic period of a five year drought caused the city
to resort to recirculation of its sewage treatment plant effluent. At
all times during the six month period that this practice was followed
the finished water from the water treatment plant maintained a coliform
bacteria concentration below the limit recommended by the United States
Public Health Service. The detergent concentration, however, increased
to a point where at the end of the drought approximately 5 mg/1 of
anionic surfactants were contained in the drinking water resulting in
taste, odor, and foaming problems. Other cases on record with the
USPHS show up to 2.6 mg/1 and up to 5 mg/1 of anionic surfactants in
well and river waters respectively. Since the 1962 Public Health
Service Drinking Water Standards set a recommended upper limit of 0.5
mg/1 of alkyl benzene sulfonate (ABS), an anionic surfactant, the need
for highly degradable detergents is well established.
At the end of 1964 the Soap and Detergent Association announced
that by mid-1965 the suppliers of basic linear alkyl sulfonate (LAS)
materials would reach sufficient volume production to enable the
manufacturers of the surfactants to change to the more biologically
degradable, or "soft", detergents. Thus in recent months as the old
rrhardn detergents have been phased out and the new more bio-degradable
''softn detergents have been put into use the reported occurances of
former detergent problems of taste, odor, and foaming have decreased.
Sawyer has noted (1) that a number of reports in the literature
indicate an increase in air (oxygen) requirements in the activated
sludge treatment of sewage since the advent of synthetic detergents.
These detergents were of the biologically "hard" type.
Sufficient oxygen must be provided in an aerobic biological waste
treatment process to meet the respiration requirements of the micro
organisms oxidizing the organic matter in the wastewater. It there
fore is of value to know if the new detergents significantly affect
the rate of transfer of the oxygen from the air bubbles to the liquid,
and consequently the microorganisms, in the aeration process.
The purpose of this study was to determine the effect of selected
"sofe' detergents on oxygen transfer by bubble aeration in distilled
water, tap water, and a synthetic activated sludge. Comparison
between the effect of detergents, concentrations of detergent,
2
aeration rates, and liquid systems were made. Depending upon the nature
3
and degree of the observed effects it was thought some changes in
aeration design criteria for wastewater treatment might be recommended.
II. REVIEW OF LITERATURE
In 1962 McKinney (2) stated, "One of the most controversial
subjects today [in waste treatmen~ is the effect of synthetic deter
gents on oxygen transfer. There is no doubt that the presence of
synthetic detergents in pure water has an effect on oxygen transfer,
but there is reason to believe that the presence of synthetic
detergents in sewage does not depress the rate of oxygen transfer any
more than other organic components of sewage. It is strange indeed
with all the research on syndets and oxygen transfer that no one has
ever undertaken a thorough study of sewage since all the data are
aimed at sewage purification plants."
4
Maney and Okun (3) showed by a survey of literature that surface
active agents (SAA) do affect oxygen transfer in waste treatment
processes and in laboratory and pilot plant studies. The reports,
however, fail to agree upon the nature of the effect and its extent.
Some researchers report that SAA cause a decrease in oxygen transfer
rate while others report an increase and a few conclude that SAA have
no effect on oxygen transfer rate in aeration systems. The conclusions
reported in these studies undoubtedly were dependent on factors such as
the nature and concentration of SAA, the liquid phase of the system,
and the type of aeration system. For example, Holroyd and Parker (4)
found that SAA interfered greatly with oxygen transfer in bubble
aeration but hardly at all with surface aeration under stagnant con
ditions. Maney and Okun (3) found that concentrations of sodium
dioctyl sulfosuccinate (Aerosol O.T.), a nonionic syndet, as low as
0.01 mg/1 caused changes in the physiochemical properties of the water
surface accompanied by increased resistance to oxygen transfer. Mixing
5
conditions affected resistance to oxygen transfer. At turbulent flow
mixing conditions in the magnetically stirred aeration cells, oxygen
transfer was dependent mainly on surface renewal and under these
conditions the SAA had no apparent effect on oxygen transfer. The
greatest effects were observed at mixing Reynolds Numbers in the
3 3 approximate range of 5 x 10 to 15 x 10 .
Maney and Okun (5) in studies on bubble aeration showed that the
presence of SAA reduces the absolute oxygen transfer coefficient(~),
while the overall rate constant (~a) may be increased. This will occur
if the interfacial area between the air and liquid is significantly
increased by the presence of SAA thereby allowing the gain in area to
more than compensate for the inhibitory effect.
Lynch and Sawyer (6) (7), in studies on eleven syndets purchased
on the retail market, found that in concentrations of 50 mg/1 as
marketed most reduced the oxygen transfer efficiency in tap water to
varying degrees. Speculation was made as to the difficulty of
maintaining aerobic conditions in waste treatment. It appeared possible
that certain syndets could cause difficulty in maintaining aerobic
conditions in the waste treatment plant. Syndets which are not degraded
or removed in the treatment plant may be capable of reducing the
reaeration rate of receiving bodies of water to varying degrees. The
effects of the detergents may last for long distances downstream
because of their biological stability and the fact that they are not
easily precipitated.
Sawyer (1) concluded that in general all surfactants decrease the
rate at which oxygen transfer occurs from the gaseous phase to the
liquid phase. Regarding the effects of SAA on the rate of reaeration
of receiving bodies of water, it was concluded that SAA residuals from
waste treatment will have little if any effect in lakes and will vary
in rivers and streams, increasing in magnitude as the degree of
turbulence increases.
6
Manganelli (8) reported that a concentration of 50 mg/1 of Naconol
N.R. (an anionic surfactant) did not hamper absorption of oxygen in
distilled water under quiescent conditions, However, in bubble aeration
approximately a 20 percent reduction in the concentration of oxygen
at saturation occurred as compared to the oxygen concentration at
saturation for the control.
Zieminski, Goodwin, and Hill (9) investigated the possibility of
improving the efficiency of aeration by the addition of small quanti
ties of certain organic substances to the aerated liquid. Alcohols,
carboxylic acids, esters, keytones, and some commercial SAA were used.
The alcohols and carboxylic acids showed a definite increase in the
rate of oxygen transfer which increased progressively with the length
of the carbon chain. The substances which were found to be the most
effective in increasing the efficiency of oxygen absorption over that
of the control were 4-methyl-2 pentanol and isoamyl acetate. The
presence of 4-methyl-2 pentanol produced increases in the efficiency
of oxygen absorption by 50 and 100 percent for concentrations of 3.0
and 6.0 mg/1 respectively.
Eckenfelder and Barnhart (10) found the liquid film coefficient,
~, and the overall transfer coefficient, ~a' to show an initial rapid
decrease followed by a constant value or slight increase with increasing
concentration of surfactant in liquids containing concentrations up to
75 mg/1 of the surfactant, sodium lauryl sulfate. The maximum decrease
7
in~ occurred over the range of maximum surface tension change. They
found that the mean diameter of the air bubbles decreased with increasing
concentration of the SAA. The increase in ~a was determined to be re
lated to both the increase in ~ and the increase in interfacial area
for transfer per volume of liquid under aeration, A/V.
No information was found concerning the effects on oxygen transfer
caused by the new biodegradable detergents studied in this thesis or
other biodegradable detergents in general as to their effects on oxygen
transfer in the activated sludge process of waste treatment.
8
III. THEORETICAL CONCEPTS
Haney (11) and others have shown that the absorption of oxygen by
a liquid under aeration conditions follows a scheme as illustrated in
Figure 1. It may be seen from Figure 1 that the rate of approach to
the saturation concentration or equilibrium condition is dependent upon
the difference between the saturation concentration, S, and the
concentration at any time, Ct. This difference, S-Ct, is called the
driving force. The driving force and rate of approach to saturation
are greater the further the system is from equilibrium.
One of the important factors affecting this rate of approach to
saturation is the formation of films at the water-air surface
(interface) which offer resistance to gas transfer (11)~ see Figure 2.
The resistance encountered by the diffusing gas molecules is due to
their collisions with the molecules in the gas and water films.
Resistance to diffusion will be greatest in the water film as the
molecules are closer together in this film. Resistance is also a
function of thickness and the gas film will probably be somewhat
thicker than the liquid film because, under comparable conditions of
turbulence, the film thickness is determined by the kinematic
viscosity, which is greater for gases than liquids (12). Although of
greater thickness, the gas film offers less diffusion resistance to
slightly soluble gases, such as oxygen, than does the liquid film.
The less soluble gases are slowly diffused across the liquid film,
therefore requiring only a small concentration difference across the
gas film. The liquid at the interface will be substantially saturated
with gas solute at the partial pressure (P) of the gas. For slightly g
~ Q) bO :>,
8 4-1 0
~ 0 bO ·~ ~ .j.J ·~ ell (/) 1-4 ell .j.J Q) ~ 1-4 Q) CJ CJ ~ ~H 0 u
s T----------T ........
.j.J
u
.j.J
u
C/)
0 L---------------~----------------------------~--0 Time (t)
Figure 1. Concentration of Oxygen in Water vs. Time
9
Air (mixed)
Gas Film
Water (mixed)
10
Concentration Gradjent
I
I I
~ < S C~( SX I s · (S) ~~----~~--~----~~.---~-----L----~----~--~~.---a-suratlon
Increasing Concentration
(Arbitrary Dissolved Oxygen Concentration Scale)
Figure 2. Absorption of Oxygen in Water
11
soluble gases like oxygen the gas film will be considered no further in
the calculations.
The fundamental gas absorption equation applicable to. oxygen in
water according to Lewis and Whitman (12) is:
.!~ A (dt)
= - P.)··························· 1. l.
w = weight of solute dissolved (mg)
t = time (hr)
dw -- = rate of gas absorption (mg/hr) dt
A = the area of the gas-liquid interface (sq em)
k = the transfer coefficient through the gas, film (mg/sq em/ g hr/atm)
~ = the transfer coefficient through the liquid film (cm/hr)
p = the concentration of solute in the gas (atm)
C = the concentration of solute in the liquid (mg/1)
subscripts i, g, L apply to conditions at the interface, the main body of gas, and in the liquid, respectively.
Note: This equation and others to be considered will apply for conditions
of constant temperature and pressure.
At the true interface P. is in equilibrium with C .• Therefore, l. l.
C. = f(P.), and this function is the solubility relationship given by l. l.
Henry's Law: S=HP .••..••..••.•........••••••••••.............• 2.
Where: S = the concentration of the gas in the water at equilibrium
P = the partial pressure of the particular gas in the air which is in contact with the liquid
H =Henry's Law solubility coefficient
As shown in Figure 2, there is practically no concentration gradient
in the gas film, therefore, P. = P and C. = HP . l. g l. g
For negligible gas film resistance, ~ = ~· ~represents the
overall gas transfer coefficient (combination of both films).
Equation 1 may then be rewritten as:
or:
C. represents the equilibrium concentration in the liquid at the ~
gas partial pressure, P , for any given temperature. g
12
By revising the nomenclature of Equation 1 and dividing both sides
by the volume of water, V, liters:
.!. ~) - (A) -V (dt) - ~ (V) (S Ct)
w As V represents the solute concentration in mg/1, this equation may be
rewritten as=
3.
in which S is the saturation concentration (mg/1) of the gas in the
water and Ct is the concentration (mg/1) of gas in the water at time, t.
d c The value ____ t represents an instantaneous rate and is not dt
applicable to any appreciable time period because of the changing value
of (S-Ct) as gas transfer occurs. See Figure 1.
Concentration changes for a given time may be found by integrating
Equation 3 between the limits of zero and t for "time" and between C 0
and C for "concentration." C corresponds to the initial concentration, t 0
or C = C when t = 0.) t 0
13
d c ~
(~) t = S-C (V) dt
t
cJct -d c ~ (A) Jt t =
s-c (V) dt t
log e s-et =-K_ (A)
S -C -L (V) t . • • • • • • • •• • •• • . • • • •• • • •• • ••• • • • . 4.
~
or s-c t =- ~
s-co; ~2;:;;..,.3_0_3
For a situation where ~~~ is constant Equation 4 may be reduced to:
log e
s-et = - K_a -L t . • • • • • . • •••• • • • • •• • • • • • •• • ••• • • • •• s-c
0
in which ~a is ~ (A) (v)
The percentage change in the gas saturation deficit, (S-Ct)' for
any given unit of time is constant, based on the deficit at the be-
ginning of the time period, Equation 3. This relationship will plot
as a straight line on semi-logarithmic paper, (S-Ct) vs. t.
Equation 5 may also be rewritten as:
5.
log (s-c _) = -K_ t + log (s-c ) • •• • • . • •• •••••••••••• 6. e t -l,a e o
which may be considered to be a straight line equation of the form:
Y = mx + b, where Y = loge (s-et) and x = t. The slope (m) is -~a
and b is log es-c). e o
Appropriately plotted data of gas absorption vs. time should then
yield straight lines until saturation is nearly reached.
IV • MATERIALS AND METHODS
A. Materials
The detergent samples studied were obtained through the courtesy
of Mr. Theodore Eo Brenner, Research Director, Soap and Detergent
Association, New York, N.Y. and Dr. James c. Kirk, Continental Oil
Company, Ponca City, Oklahoma.
14
Interim Reference Sample LAS Lot. No. 1-1 from the Soap and
Detergent Association was a blend of several unspecified commercial
linear alkylate sulfonates provided by several manufacturers and having
an analysis as follows~ (13)
linear alkylate sulfonate
sodium sulfate
free oil
water
molecular weight
60.8%
36.1%
0.4%
2.7%
348
"Nalkylene" 550 Alkylate Sodium Sulfonate -Sample No. 8302 D from
the Continental Oil Company has been commercially marketed since early
1965 (14). The detergent alkylate is derived from normal paraffins
of c10 , c11 , c12 , c13 and c14 hydrocarbons in such a ratio that the
molecular weight of the final linear alkylbenzene sulfonate prepared
therefrom is about 340. The normal paraffins are first chlorinated and
the resulting chloro-paraffins are used to alkylate benezene to make
the linear alkylbenzene. This product is then sulfonated with sulfur
trioxide and neutralized with sodium hydroxide to form a slurry (14).
The analysis of this sample was~
linear alkylbenzene sulfonate
unsulfonated alkylbenzene
46.5%
0.25%
15
sodium sulfate 5.25%
water 48.0%
nAlfoln 1216 Alcohol Sodium Sulfate - Sample No. 8303 D also from
the Continental Oil Company was made from an alcohol blend of
approximately 65% dodecanol, 25% tetradecanol, and 10% hexadecanol which
was sulfonated with sulfur trioxide and neutralized with sodium
hydroxide to make a sodium alcohol sulfate slurry (14). The analysis
of the sample was:
alcohol sodium sulfate 30.1%
unsulfated alcohol 2.0%
sodium sulfate 1.1%
water 66.8%
Solutions of the three detergents were prepared with demineralized
water to give an active agent concentration of 1000 mg/1 of stock
solution. Detergent concentrations of 2, 5, and 10 mg/1 of aerated
liquid were chosen for use as this is within the range of reported
concentrations found in wastewaters.
The tap water for this study came from a well serving the
University of Missouri at Rolla. An analysis showed this water to have
a pH of 7.5, turbidity of 5 units and a total hardness of 220 mg/1 of
equivalent calcium carbonate of which calcium hardness comprised
115 mg/1.
The distilled water was obtained by condensing steam from the
school power plant. No analysis was made of this water.
Before being used, both waters were allowed to reach room tempera-
0 ture (23-24 C).
16
B. Methods
Two liters of distilled water, tap water, or activated sludge,
including the detergent solution, were used as the experimental
aeration volume. The liquid, without detergent, was added to the
lucite aeration column, 4" I .D. X 27" high, (Figure 3) and the
dissolved oxygen, DO, was sparged with nitrogen gas. The nitrogen was
supplied from a compressed gas cylinder through a pressure regulator
and into the liquid through a diffuser. The DO content of the liquid
was reduced to approximately 0.2 mg/1 as the initial concentration
for each aeration period. The actual DO was determined with a galvanic
cell oxygen analyser (Precision Scientific Co., Chicago, Illinois).
The detergent was added following the sparging so as to avoid foaming
prior to commencing the aeration. Before starting aeration the liquid
was gently stirred to disperse the detergent.
After obtaining both the initial temperature and DO with the
analyser, the aeration was started at the rate of either 300 or 600
ml/min/1. These aeration rates correspond closely to those used by
Ludzack (15) for a laboratory model activated sludge unit. The air
flow rate was observed and regulated through the use of a rotameter
(Fischer and Porter Co., Hatboro, Pennsylvania).
DO and temperature readings were taken at one minute intervals.
The total period of aeration was governed by the time required for the
liquid to reach oxygen saturation as determined by the DO analyser.
The length of most periods of aeration was fifteen minutes, saturation
usually occurring within this time, however some check readings over a
period of thirty minutes to one hour were taken to assure no appreciable
change in DO had taken place after the initial series of readings had
been made.
17
Figure 3. Experimental Equipment
18
A check on each series of readings was made by repeating the test
with the same aeration rate after sparging the previously used liquid
(in the case of distilled water and tap water) with nitrogen. When
the liquid, rate of aeration, or detergent concentration was changed
the previously used liquid was wasted and the column thoroughly flushed
and rinsed before adding liquid again. A fresh volume of activated
sludge was used for each aeration period.
The activated sludge used in these tests was started from a "seed"
sanitary waste obtained from the outfall of the trickling filter
wastewater treatment plant south of Rolla, Missouri. It was grown on
a synthetic waste composed of the following constituents in the given
concentrations:
tap water ...•.....•...•..•.......•.............•. 100 ml/1
glucose ...........•.....•.•.....•................ 1000 mg/1
ammonium sulfate, (NH4) 2so4 .••••••••••••••••••••• 500 mg/1
ferric chloride, Fe(Cl) 3 .6H20 .••••••••••••••••••• 0.5 mg/1
calcium chloride, cacl2 .••••••••••••••••••••••••. 7.5 mg/1
manganese sulfate, ~so4 .H20..................... 10 mg/1
magnesium sulfate, ~;so4 .7H2 0 .••••••••••••••••••. 100 mg/1
1 M potassium phosphate buffer (pH7), K2HPo4 , KH2Po4 ••••••••••••••••••••••••. 10 ml/1
The following procedure was used for the once a day feeding of the
activated sludge units (Figure 4). The air supply was shut off and the
sludge allowed to settle for approximately thirty minutes after which
time the top 1.5 liters were siphoned off, the synthetic waste added,
and distilled water added to bring the volume to 3 liters. Aeration
was then resumed.
19
The sludge used in the aeration tests had not been fed for 24 hours
and was in the endogenous respiration phase so as to minimize the effect
of its oxygen uptake. Eckenfelder and O'Connor (16) have reported the
endogenous respiration rate of activated sludge as 1.85 to 9.8 mg
02 1hrlg of sludge.
The biological solids concentration of the sludge was determined
by optical density using a Bausch and Lomb Spectronic 20 Colorimeter
(Bausch and Lomb Optical Co., Rochester, N.Y.) and a plot of optical
density vs. biological solids (Figure 5). The necessary dilution was
made to obtain a biological solids concentration of 1200 mgll which was
used in the tests. An optical density check on the solids concentration
was made following the dilution.
The dissolved oxygen, DO, content in mgll was determined through
the use of a galvanic cell oxygen analyser. The probe consisted of a
cylindrical silver cathode surrounded by a lead anode and set in a
ceramic material. The exposed end of the probe was covered with a pad
treated with potassium hydroxide electrolyte which in turn was covered
with a 1 mil thick polyethylene membrane held in place with a collar.
The probe was connected to a micro-ammete~JA a, calibrated to read
mgll DO. In order to determine the actual DO a probe sensitivity
coefficient, 0, was applied. Actual DO=}' a reading I 0. 0 was
determined for each test by calibrating the probe in a solution
identical to that used in the test. The Alsterberg (Azide)Modification
of the Winkler Method (17) was used to determine the actual DO content
of the calibration sample. 0 =~a reading I actual DO. The analyser
was also equipped with a thermistor for direct temperature reading.
For samples with temperatures different than those of the calibration
20
rigure 4. Activated Sludge Units
0.6
0.5
:r.. ~ 0.4 0 ..;:t U"\
.j...J
t1l
:>-. .j...J
•r-1 Cll s:: 0.3 <I)
A ..-1 t1l u
•r-1 .j...J
8' 0 . 2
0.1
0 100 200
Figure 5
Optical Density vs. Biological Solids
from
Dr. Don F. Kincannon Oklahoma State University
Stillwater, Oklahoma 1965
300 400 500 600
Biological Solids (mg/1)
700 BOO N f-'
22
sample, ~ was adjusted by use of a scale provided by the manufacturer
of the analyser. During tests the probe was suspended at the approximate
mean depth of the liquid as shown in Figure 3 and manually agitated.
V. PRESENI'ATION OF RESULTS
In order to present the effects of the selected detergents on
oxygen transfer, graphs were plotted of the dissolved oxygen deficit,
S - Ct, in mg/1 versus elapsed time, t, in minutes for each test
condition.
The value of the theoretical solubility concentration of oxygen,
S, was determined from Standard Methods (17). Ct, the oxygen
23
concentration in the liquid at time t, was determined from the corrected
oxygen analyser reading, tl a I ~.
The following Figures 6 through 23, showing the plots of (s- C ) t
versus t are arranged on the basis of liquid system (distilled water,
tap water, and activated sludge), aeration rate (300 and 600 ml/min/1),
and detergent studied (LAS #1, Alfol, and Nalkylene). Each figure shows
curves for the effects caused by 2, 5, and 10 mg/1 of a particular
detergent under the test conditions. A curve for the "blank", no
detergent in the aerated liquid, is also shown. References to the
effects of the detergents are made with respect to the "blank."
A. Distilled Water System
Theoretical oxygen saturation, (S-Ct = 0), was not attained in
this system at either aeration rate as evidenced by the fact that the
dissolved oxygen deficit curves became horizontal, indicating that
saturation had been reached, before Ct equaled S. From Figures 6 through
11 it may be seen that the theoretical oxygen saturation was more closely
attained by the 600 ml/min/1 aeration of the "blank" and the 300
ml/min/1 aeration of the distilled water containing a concentration of
2 mg/1 of LAS #1 than any of the other distilled water systems. To
varying degrees, all detergents may be seen to exhibit effects on R,
the rate of approach to theoretical oxygen saturation, s, and the
dissolved oxygen deficit, s - ct.
24
From Figure 6 it may be seen that the 2 and 10 mg/1 concentrations
of LAS #1 increased R when aerating distilled water at a rate of 300
ml/min/1. The 5 mg/1 detergent concentration R was slightly less than
that of the "blank." The 5 mg/1 concentration increased the DO deficit
over that of the "blank" by approximately 0.02 mg/1 as apparent
saturation is reached, while the 10 and 2 mg/1 concentrations decreased
the DO deficit by approximately 0.1 to more than 0.3 mg/1 respectively.
From Figure 7 it may be seen that the 10 mg/1 concentration in
creased R more significantly than the 2 and 5 mg/1 concentrations whose
initial R values closely corresponded to R of the "blank" when aerating
distilled water containing Alfol at a rate of 300 ml/min/1. All three
concentrations of Alfol produced a DO deficit less than that of the
"blank." At an Alfol concentration of 10 mg/1 the DO deficit at
apparent saturation was not significantly lower than that of the "blank",
however, the 2 and 5 mg/1 concentrations decreased the deficit by
approximately 0.14 and 0.16 mg/1 respectively.
From Figure 8 it may be seen that the R values increased slightly
with detergent concentration but did not differ greatly from R of the
nblank" when aerating distilled water containing Nalkylene at a rate
of 300 ml/min/1. All concentrations caused an increase in DO deficit
from that of the blank ranging from approximately 0.41 to 0.31 mg/1 for
2 and 10 mg/1 of Nalkylene respectively. The effects of the 5 and 10
mg/1 concentrations may be seen to be comparable to one another.
In Figure 9 (aeration rate of 600 ml/min/1 of distilled water
containing LAS #1) it may be seen that although the initial R values
increased slightly with an increase in detergent concentration they
-~ :f
........ .. +)
0
I
Cl) .. ~ ()
•rl lH Q)
~
~ Q)
g '1:1 Q)
~ 0 11) .,
orl ~
25
8 •· 0 ~.lr-+---t--1--1---t--i--:+--t--t--r--r-.--.----r~ ~
6.0
5.0
4.0
3.0
2.0
1.0
0.8
0.6
0.5
0.4
- 'l\ - -- -- ---- - - --- t-- .. - . - -- -- ..
"' -- ~ ---
~ ~ r-- --l---f---1f----t--t--t---r--t - - - ---
~\ -- -- _\\. - --·
-== -~~~ -- ----t--t--1
-~~-+---~--~-r--~--t---r--- ---
·· t--- - __ ----::_ --1----1---- t----t-- '---
- --- -- f-- ---- -- . r---- ---- t--
-- t-- r--- --. Bl nk 0
-- - 2- ~gfl f-1!1 5 ~g/1 A
10 ~~ 1 --x
-- t--
1-------1---- - .. - -r--- --\\· - -~~ ~ - --
-~-- ---- ----- - ------ --- ~l ~~ -- --
- ---- ------ --- -~~~ l~~ -0.3 ~-_-+_ -__ -_ 4-_~~_-__ +-_-_+-~--~. ~~Jr~~-~:-1r------r~---~v~-----~r--- ~_ rr_-__ ~
f--- --- --- ---r---l--t---t-1~~ ..... ~ . --~ ---. ---- - - ----- ---+---0: -- - -r-----+==1~~~~---~
0.2 ~~--~-r--+--+--+--+--~~~;-~r-~~r--j-. ---- -- - -- -----r--\ -- -· :-·r-- - -
--r--- - - 1----- \ 1---
---t- ---t-- -- -r-- -~\ -
0.1~~--~--~_. __ ._~--~--~~--~----_. ________ __ 0 2
Figure 6.,.
4 6 8 10 14
Time, t, (mi.ri;)
D1ssq4ved Oxygen Deficit vs. Time for 300 ml/min/1 Aeration of Di~tilled Water Containing LAS #1
,I',
26
10.0
,....., r-l
' ~ ..._, .. +'
0
U) .. ...., ..,; 0
·ri 44 v
0
t:: Q)
bD
$ -o Q)
~ 0 II) II)
..,; 0
8.0 i :x 6.0
5.0
4.0
).0
2.0
1.0
\ ~ l~ -·-- --··- - ---- - - -- - - - -- -
- \\ ·-~- ··- r--- --1--- -· . - . ---
1--- ,~ ------ --- -
----- --- ~ \~ r-- - - ·-· - - -· -I--- 1--- - '---
~ - -- -· -- - ·-· I--'-
'\ \\ .. -. -- -· -· - - ·- f---·
- --· \ ~~ -- -- ,____ - '---·
\ '~ Bl nk 0 --· -- - - '1 gfl H1-
-\ ~ -· ·-- ---- ... - - -·
~ 5 pg/1 A -- ... -- -*·
~ r---
.LU ngt 1 ·-·- ·-
\ '\~
0.8 \ \ \ C\._ \'-.
0.6
0.5
0.4
O.J
0.2
\ f\ ~ - --f--- --I-'- 1-- -~ ~~ ~- --· ---- ·-- --
f-- -· -- -- --· -- --~'\ ~' ~ r---- !--- , ~~
~~ (\ ~ ~~ ' __ ,. -- ---- - -·--- - -·---- ~ 1--
l ' "'-.: " - · --- --- - ---- - -- - .. - 1--
- - ---- --- - - - N ~ -r--- - -· - --- - ~ ~ ----1
kc ........., ~ ~
-- - -· -·-- -- -· --- -- - _ _4 ~~
- ·--·
·- ··--f--- --·· "1
0.1 0 2 4 6 8 10 12 14
Time, t, (mill~ )
Figure~- Dissolved Oxygen Deficit vs. Time for 300 ml/min/1 Aeration of Distilled Water Containing Alfol
27
8.0 ~~~-t--!--+-t-r-+--+-+-1--+----t----+---l----l
\ 6.0 ---1[-·-5.0 \\.
f- -
4.or--r~\\~~4-_,--+--+--+-~--~~~~4--4--~~ - ~~k c---~-1---·1---1---- --f---·1---·- --
-f--- ------ --1----
-. --- 1---- --·
0.3 - --1---f.---
··- --·· ----- -- - --- --1---- -- --1---- -- ·-- --1---
-- f---- ·- -- ----- --1--+---- ---- ·- ---
0.2 ~-+--4---~-+--+-~--~--+--4--~--~-+--4-~~~ - -- . - -- -- --· --- -· --1-- -
- --- 1--- --!---·- - -+---1---- ----· ·- f--
--- --- -- --· - ---~~ -- --1---~-+- 1----+- - f-..
0.1 ~~--~~--~~--~~--~~--~~--~-L--~~ 0 2 4 6 8 10 14
Time, t, (llli;i~)
Figure~· Dissolved Oxygen Deficit vs. Time for 300 ml/min/1 Aeration of Distilled Water Containing Nalkylene
28
did not exceed the R value of the "blank", but corresponded closely to
it. The DO deficit increased with an increase in detergent concentration,
ranging from approximately 0.1 to 0.3 mg/1 for 2 and 10 mg/1 of LAS #1
respectively.
From Figure 10 (aeration rate 600 ml/min/1 of distilled water
containing Alfol) it may be seen that the R values for the 2 and 5 mg/1
concentrations were slightly less than R for the "blank'r, whereas, R
for the 10 mg/1 concentration was slightly greater than the "blank."
The presence of Alfol in all concentrations tested increased the DO
deficit over that of the "blankrr by approximately 0.3 mg/1.
In Figure 11 the Nalkylene displayed slightly increasing R values
with an increase in concentration when distilled water was aerated at
600 ml/min/1. The R values for the detergent concentrations, however,
were not greatly different from R of the "blank" in the early minutes
of aeration. The various concentrations of Nalkylene in this system
caused oxygen saturation to be reached at approximately the same time
and approximately the same DO saturation as one another. All Nalkylene
concentrations caused a DO deficit approximately 0.6 mg/1 greater than
that of the "blan~r at saturation.
B. Tap Water System
From Figures 12 through 17 it may be seen that for the test
conditions the oxygen saturation concentrations attained were less than
the theoretical oxygen saturation concentration by approximately 0.4
mg/1 or more. The rate of approach to saturation, R, for the aerated
tap water containing the tested detergents may be seen to vary from
values close to that of the "blankrr to values of R less than that of
the "blank."
29
lo.or--r--r--r--r-,--r--,-~--~~--T-~--~~~
..........
~ ~ '-' ..
+) 0
I
Cl)
s.·o ~~-r~-r--r--t--+--+--l-+-+--+--t--+--l---J 1
6.0 \
5.0 ,
4.0
- ~ --- --
-- I---- ;-----
~\ - ~ - ----- - ------1---+--- 1---
,\ r---
3.0
2.0
~ - --- ------- ------ - - - -t---1-- 1----- - -
~rL --- -- :-- "' --- ----- --1--'--- ----~ ~\ - ·- - - --- -1--1----- -- ----- -·-- ---- - ------ ---
2 4 6
-- ---- -- - +--- --- ---- t--Blank <:>
. -- --- -- - -- £ " ifg/1.-a- --
8
5 ~g/1 A --- 1()~1~ --·-
-·
1~ 12
Time, t, (mir1~)
Figure~. Dissolved Oxygen Deficit vs. Time for 600 ml/min/1 Aeration of Distilled Water Containing LAS #1
30
1o.or--r--~~--~~--~--~-r--~~--~~--~--r-~
,......,
< ~ -.. ~
0
I
Cl) .. +l ....... 0
•rl 4-t d)
0
s:: Q)
bO g 't:1 Q)
> r-f 0 en en .....
Q
t
6.0 ' \
5.0 '
4.o L ~- . ~\ ----- --- - - -- --~----- ----
3.0
2.0
1.0
- ~\\ ---- ------ ----- -- - - ----- --· -- ---- - r----- '---w• -- -- -------- -- --~ --- -- -- ---- -- - ----
.. .. ~~---·--- ~~\ --
- ---Bl nk 0
-L ~g/1 ~-- ~--
5 rg/1 A --- f----- 10- ~g/1 )(
\\ \J~ 0.8
0.6
0.5
0.4
0.3 -- ~~ -=-~ = =-= :_-_- ~- --- --- -_-_ -~- ~~
-~=-~ ---_ ----- ----- --~ ------·--- '.. -- -- ---; 0.2 ~~-+--~~-4--+-~\+-~~--+--+~~,_-T~
---~- ---
-~- -~---~ -·-j~ -- --------·-
['., 0.1 -L-~--~~--~~--~~--~~~~~--~~--~~
0 2 4 6 •, 8 18 12 14
Time, t, (mill~)
Figure 10. Dissolved Oxygen Deficit vs. Time for 600 ml/min/1 Aeration of Distilled Water Containing Alfol
; ,.
31
lo.or--r--r--r--~-r--r--r~--~~--~~--~~~
,...... .c! ~ ..._..
.. +)
0
I
Cl) .. +)
"" () ...... ~
C1) ~
s:: Q) bO g
't:1 C1)
~ 0 It) It)
"" Cl
8.·o .-ll-ll-t-t--+---+---1f---t--+--+-t--+--+-~
4.0
3.0
2.0
1.0
0.8
0.6
0.5
0.4
0.3
l -. -·
-- r---
.. - f--..- - -. - --f---- ---
··-·· ---·-· --r----- r- f--- -- :------·
Blank (!) --z mg/1 -a
5 mg/1 &. -- 10~, -x-
--------
·------ - --1\ -- - ·-\'~- - --- .. -- ---- ----. ----- . -- ----. f-
-
--- -- ---- - "' -~- ~-~- --~~ ~~:~_-=::____ - r---\---- ----- ---·- ---- -- ------- --
0.2 r--+--+--_~-.~. -- ~--~-~ __ ~\ __ +_--+-_-.. _~ .. _-___ ~------~---~~-----+--+~
- ---- -·-. -· -~ - -- - -- -- -
.. - - - - - - -. -- ·--- ----~ --1-----lf-- f-- --- -
' 0.1 ~~--._~--~--~~--~~--~~--~--~_. __ ._~ 0 2 4 6 8
Time, t, (miri~)
G> 10 12 14
!igure It. Dissolved Oxygen Deficit ·vs. Time for 600ml/min/1 Aeration of Distilled Water Containing Nalkylene
''· .. . . .' ~:·~~ ~, .. /~,~·*·,;"'·
From Figure 12 it may be seen that the R values were decreased by
the presence of LAS #1 when aerating the tap water at a rate of 300
ml/min/1. At the end of 10 minutes aeration, as oxygen saturation was
approached for the systems containing the LAS #1, the 2 and 5 mg/1
detergent concentrations may be noted to have caused a DO deficit of
approximately 0.17 mg/1 greater than that existing for the "blank".
The 10 mg/1 concentration exhibited a DO deficit of approximately 0.12
mg/1 greater than the rrblank" after the same period of aeration.
From Figure 13 it may be noted that all of the concentrations of
Alfol caused a slower approach to oxygen saturation, lower R,than that
shown by the "blank" when tap water was aerated at 300 ml/min/1. It
may be seen that the 2 and 5 mg/1 concentrations of Alfol caused a DO
deficit at 12 minutes which was greater than that in the "blank" by
32
0.12 and 0.02 mg/1 respectively but were still approaching the deficit
shown by the "blank." The 10 mg/1 concentration approached oxygen
saturation with a deficit less than that of the "blank" by approximately
0.1 mg/1 after 14 minutes of aeration.
From Figure 14 it may be seen that the R values did not vary greatly
for the 300 ml/min/1 aeration of tap water containing Nalkylene. The
10 mg/1 concentration of Nalkylene reached oxygen saturation with
approximately the same deficit as the "blank." The 2 and 5 mg/1
concentrations may be seen to have DO deficits less than that of the
"blank" by approximately 0 .OS and 0.12 mg/1 respectively after 13
minutes of aeration.
In Figure 15 (600 ml/min/1 aeration rate of tap water containing
LAS #1) it may be seen that the R values for the systems containing
the LAS 411 were slightly less than that of the "blank", but no
significant difference in R appeared among the detergent concentrations
33
1o.or--r~--~~--r--r-,--~~--~~~--~~~
a.·o 1\i\--t-r---t----t--t-~--:+--f--+-+-+-+--+--t.-l H\rt-~r-r4-+~~~+-~~-L~
6.0 ,, 'K
5.0 ~\\~~+--+-___ +_- __ t---+--1---+--+--~-l--L.J_J \\ --- r-- f--
4.0 ~ >----- -(~- _, __ ----- - -------
~ 3.0 ~~ -~ - \' -· - - -- --·- - -- ;---- ---- - -s -~~-~- -=---.... ~ ~
0.3
----- --- -- --Bl~nk 0
..... -L~f-8 ---5 lng/1 A
- 10 ngy-i -x- ... -
· - ·-- -i---- --- f--
--- ---- ------- ----· -- --- --- --- -- --- --- --1-- - -- ---- - 1- --+--1-- ·
--- ----- ----- -----+---~- -- -------1
----~-
-·-- -----· -· ·----- ----- - - --t--·1---1--1--~-
' --- ---- ---- - - --- - - f---f--f---- ....._-+--+--1
0.1 -L-~--~~--~~--~~~~--L-~--~~--~~~
0 2 4 6 8 10 14
Time, t, (miri~)
Figure 42. Dissolved Oxygen Deficit vs. Time for 300 ml/rnin/1 Aeration of Tap Water Containing LAS #1
34
1o.or-~r~--~-r~--~-r~--~~~~--r-~~~
8.0 ~\~--t-t--t--f--+~~~+-+--+---t---t-L--1
~ 6. 0 --\\:- '---- ---- -··- - -- f--- --
5.0 \'~ ---- --------\ J..'\ - ----·
4.0 \~\
~~~
------------
0.3 ---- --l----1----- -
--- -----1------------1--- !---- -- ---· ----r---
-- ·--· -···· - --- -- . - . ---- --- ----- -- >-- ---· -··· ·-
0.2 r--+--+-~~-r--+-~--~--~-+--4---~~--+-~--~ --- f-f-- -
-------------- ----1---t--f-- --- --1--
·- ... -- --··· ----- ·---- -----1---+-·-
0.1 L-~--~--._~--~--~~--~--._~--~--~~~~~
0 2 4 6 8 10 14
Time, t, (~l)
Figure ~3. Dissolved ,Oxygen Deficit vs. Time for 300 ml/min/1 Aeration of Tap Water Containing Alfol
10.0 ·r-..,---,-.,--r-r--r---,-..,..--,..-.,..--,----,-..,...---.--..
8 •· 0 1\\-t-t--t--t--t-11-+--+--+---t-+--1---+---!.--J
\ -- f--- ----- --6.0 -- ~ ~ -- --- ---- ---
5.0 " ----------e---- --- --- - --1----4.0 ,, l
,&- '--··· · \\\ , - ,---- ---t---1--- 1----1-- i-- --1---
---- - 1-1--1--- --1-- ------ ---1--- --·1----1---~-- --1-- ----- ---1---
--- -----· -----1-- --- 1-
---- 1--- -- -- - -- -- - - --· -- --· ---- -- 1---- 1--- - --- -
---- --- --1-- +--1--1-----1--- t--•----+---1--t--r--
-----f--- - - - --
0.1 ~~--~_. __ ._~--~~--~~--~~~~--~~~
0 2 4 6 8 10 14
Time, t, (miri~)
Figure tb. Dissolved Oxygen Deficit vs. Time for 300 ml/min/1 Aeration of 'fap Water Containing Nalkylene
36
themselves. As the DO saturation is reached, all the concentrations
may be seen to have a DO deficit of approximately 0.3 mg/1 greater than
that of the "blank .n
From Figure 16 (600 ml/min/1 aeration rate of tap water containing
Alfol) it may be seen that increasing the concentration of Alfol caused
an increase in R, but only the 10 mg/1 concentration increased R to a
value greater than that of the "blank." No significant change in DO
deficit at saturation may be noted from that of the "blank."
In Figure 17 it may be seen that all of the concentrations of
Nalkylene caused decreases in R over that of the "blank" when aerated
at a rate of 600 ml/min/1. The greatest differences in the DO deficit
from that of the "blankrr at saturation, 0.28 and 0.20 mg/1, were
exhibited by the 5 and 10 mg/1 concentrations respectively. Saturation
was reached after nearly the same aeration period in all instances.
C. Activated Sludge System
From Figures 18 through 23 for the activated sludge system it may
be seen that the rate of approach, R, to oxygen saturation of the liquid
and the DO deficit, S - C , were affected to varying degrees by the t
type and concentration of detergent present. The rate of aeration may
also be seen to have an effect. By increasing the aeration rate from
300 to 600 ml/min/1 the increase in rate of oxygen transfer in the
rrblanks" was approximately doubled in the early minutes of aeration.
The DO deficit at saturation in the "blanks" decreased with the in-
creased aeration rate from approximately 3.6 mg/1 at 300 ml/min/1
aeration to 3.35 mg/1 at an aeration rate of 600 ml/min/1. It may be
noted that this system at saturation was the furthest from theoretical
saturation of the three liquid systems studied.
37
1o.or--r-,--~~~r-,--.--~~~--~--~-----
-.c:! ~ ......., .. ~ I
Cl) .. +) ...t ()
...t f+-4 Q)
~
s:: Q) bO g '0 Q)
~ 0 11) 11)
...t Q
8.·o l\~1---t-t--t--t--+-+-+-+---t----.j~!-..L-L_J
\ 6. 0 '--\t-r-r-r __ = t-_-__ i-t-__ -_ t_-__ l--1-·~~- -1--1--+--4--_ -J_ -___ _j
5.0 J
4.0
3.0
2.0
1.0
0.8
0.6
0.5
0.4
.... [ "' --t---1--- ·1---f--- --
" ---r-~~~~.---+-~1- ---1---r---t--t---t--~-+-+-- t--·
·-\,1~\--\ -l---· --·--- ----t---t--i~-1---1-- t--- t---1-- ·1----'-
l~ ·- -+---1- -l---- -l-- ---1-·--
- -- ·- t---t---+-- --1-- lf-- f- - 1---BUank E)
\ 1----l--- --r--~ ~ -- · - - -- 1-- -··- ·- f-1--
--------- -----. ---· _ _c~b 1--- -- f--r--
-s- --I--
A )( --- - -
-1--·--
---· --- -- - -- -- - -- --t--·t---1 ---1--
0.3 r---t----+---,_--r--4--~--4. --~--4-~~-+--~--+--4--~ .. ---- --f--1- - --
-- --------1--- -1-1-- ---- ---~
--- 1--- ---~ ---1--r---- ·- 1--
0.2 r--+--~-+--+--+--+--4--4-~--4-~~~~--~~ ----·- -· ____ .. -1-----1-- ·+---1----·-·-
---- ·-- --1--+-- --1--1---J.--+--~-- -- --I-
-·-· --·--- -- ----- --+--- -----t---t--,~-+-~-+--+-~
0.1 ~~--~~--~~--~~--~~~~~~--~~~ 0 2
Figure );..5.
4 6 8 10 12 14
Time, t, (mifi;.)
Dissolved Oxygen n'eficit vs. 'l'ime for 600ml/min/1 Aeration of Tap Water Containing LAS #1
,..... .c! rf .._, .. 0~
(/) .. ~ ..... () ....
f+..4 Q)
0
s::: (1)
i '0 Q)
~ 0 Cl) Cl) .....
0
4.0
3.0
2.0
1.0
0.8
0.6
0.5
0.4
0.3
·- -- ----+---- -- ·--
·- - --t--J--J.--1--r--t--+---1--
1\\ --t--\\-\oh\\c-- 1 --- --
38
·_ . ~~l\c ---_ -= ~--- -- 1-f--1--K\\ ~ -1--· -- f-- --. f----
---1---1-- --f--- "\.\ --1-- -- t-- ---· !---- ·-·~ . ""'K + --- 1--·-·
-- --- --t--1--- - 1----
-- 1--1--- 1--+--~ 1--- -
1- --- ---1---1---1-- ·-4---1-- --l--1--- 1-- 1----1---1--·
··-1-- ---- --- -- ---+-+--1 --1-
0.2 r--+--r--+--+--+--+--4--4-~--~--~~~~~~ ---- -·-- -- ---- - 1-- ---1----1---1-1---t---~-
- 1---- - 1---t---1---f--1---+--.J--1---1---~-il--
-·- -- - --- ---1- -1--
0.1 ~~~~--~--~--~~~~---L--~--~~~~--~--~~ 0 2 4 6 8 10 14
Time, t, (Ddil)
Figure 16. Dissolved Oxygen rieficit ·vs. Time for 600 ml/min/1 Aeration oJ Tap Water Containing Alfol
,-...
~ ~ ........ .. .+)
u I
Cl) .. .+) ..-1 ()
..-1 ....... Q)
0
t:: Q) tiO g
"d
~ 0 It) It)
..-1 0
39
10.0
a.o l 1\ 6.0
5.0
\ -\ - ---- 1----- --- ---·· - - ·· f.----- -- - -
~
4.0
3.0
2.0
1.0
~ -- 1---1--- --1--- - -- - -· -- . --
~\ 1--1--
~\ -- -- - -- -
-- ----~· ~ -- -- --· - - .. - 1---f-- 1--f.--- -- ·- - --- -·- -- --1-- f-·-1--· --- 1---
f--·- -- --1----1- -- - f.--· -- -- - ·-
----I~ l ---· -.\
- ·-· tlnk ·- --Bl G)
t--2-~ ·"'1 1:\
\ ~\ --- -- - · -·- - --
~~1 · t--
5:1. • ·-~-- ----
~~ ~ - - ---· - iU-' ,!uX ~/J
- -
\~ "' """ O.B \ ~ "' ....... ~
\\ ~ ~ f-..-~
0.6
0.5
.. ~ ~ .......... ~·~
1--- - 1--- ----~ ~- ----- 1---- --- - -- . ·-·-· ··- - -
1--I--1-- -- - ~~ N L lr· 1-- 1---~
0.4 '
-·-- -- ---- -· --- ----·· 1--1-- -
0.3 --· - ·--· -- ---- ---- -· ·-- f-- -- f.- - -· ----- -- --f--- 1----f---
-- ---- ---·-- ·- --- ---- ---- -- -· t---
0.2 - --· -· --· --- ----1- - -· -
---· --1- -- -
·- --- - t---
0.1 0 2 4 6 B 10 12 14
Time, t, (JDiil)
Figure l7. Dissolved Oxygen Deficit vs. Time for 600 ml/min/1 Aeration of Tap Water Containing Nalkylene
40
From Figure 18 (300 ml/min/1 aeration of activated sludge con
taining LAS #1) it may be seen that an increase in the concentration of
LAS #1 increased the DO deficit at saturation by approximately 0.2 to
0.4 mg/1 for 2 to 10 mg/1 of LAS #1 respectively.
The effects of increasing the aeration rate to 600 ml/min/1 are
shown in Figure 19. The 5 mg/1 concentration of LAS #1 may be seen to
have increased the DO deficit slightly. The 2 and 10 mg/1 concentrations
decreased the DO deficit by approximately 0.3 and 0.15 mg/1 respectively.
The presence of Alfol in concentrations up to at least 10 mg/1 in
the activated sludge under aeration at the rate of 300 ml/min/1 did not
significantly affect the DO deficit at oxygen saturation compared to the
"blank" as may be seen from Figure 20. Concentrations of 5 and 10 mg/1
increased the rate of approach, R, to oxygen saturation over that of the
"blank."
From Figure 21 it may be seen that while the increase in aeration
rate from 300 ml/min/1 to 600 ml/min/1 caused a decrease in DO deficit
at saturation for the "blank" of approximately 0.25 mg/1 it increased
the DO deficit for the activated sludge containing Alfol. This increase
was greatest for the 2 and 5 mg/1 concentrations, having raised them by
approximately 0.4 mg/1 over what they were at the 300 ml/min/1 aeration
rate. The 10 mg/1 concentration caused no change in effect from that of
the "blan~' at the aeration rate of 600 ml/min/1.
From Figure 22 it may be seen that the 10 mg/1 concentration of
Nalkylene initially increased the R value over that of the "blank" a t
300 ml/min/1 aeration. The other concentrations had R values closely
corresponding to that of the "blank." All studied concentrations of
Nalkylene reduced the DO deficit at this rate of aeration by
approximately 0.2 mg/1.
41
From Figure 23 it may be seen that for the increased aeration
rate (600 ml/min/1) all initial R values for the Nalkylene concentrations
in the activated sludge corresponded closely to that of the "blank." The
DO deficit as compared to the "blank" increased by approximately 0.1 mg/1
for the 2 mg/1 concentration, remained unchanged for the 5 mg/1
concentration and decreased by 0.3 mg/1 for the 10 mg/1 concentration.
42.
1o.or-~r~--r-~~~--r-~~~--r-,-~--~~~~
,......,
<!. ~ ......., .. rf I
Cl)
8~o r~"~-t---t-r-t-+--+-+++-+-+-t--J_J
6.0 ~~~~~- .. -- --t--t--t-t-_-t_ ._-___ -+-+-+----l--+--!---1 5.0r-1!-1~_,~~- ~~t~~t--r~--+--+--~~~--+-~_j 4.0
3.0
2.0
~ --. ,___ --f-- f--.-- --
-------t--t---+--1---+--t---1~- 1----
--------- ---f--- r--------f--
- - - ------ 1----- ·--· . -- 1---··
--- ---- --- f---· - -- --Bl~nk 0
---2 t~t'-lra- ·--s·, ~tl A
" --- ·---- ---- - ·to , Dg-/1 -- )( +) ..-i ()
~ 1.0 r--t--t-~r--t--t-~--~--~-+--4-~~~--~-t~ Q)
Cl ~ 0.8 r-1-r--t-t--t--t--t-+---f-+~--1---1-+-~
» o.6r-~~--r-~-+--~~-+--~4--+--~~-+~ "0 ------ -- --- --- --- - -- -- --- -- --- ---··· -- ---i 0.5 ~~--1r~~-t_-_--t---r-~---_ -_+_--~t-~~---4----~~----~---_4--_-_+~-----~~ ~ 0.4 r--T--~~r-~--+--1--~--~-+--4---~~--+--+--~ iS
J ... ' ·:. - !
--1---- - -- --- 1-- -
0.3 ---- - -- f-- --
. -- --- . --- ---1--- - - . -- ----
. - - ---1---+- ------ --
-- 1-- -- --- --1---+--
0.1 ~~~~--~--~--~~~~--~--~--~~~~--~--~~ 0 2 4 6 8 10 12 14
Time, t, (mii~)
Figure l8. Dissolved Oxygen Deficit vs. Time for 300 ml/min/1 Aeration of ~tivated Sludge Containing LAS #1
4:3
10.0~~--~~--~~--,-~--~~~~~~--~~~~
8. 0 ~l~--t--r--t-·f--i--:-1-+--+--+-+--J---l--+-~ ~
' 6.0~~~~- ~_-+_.-___ ~-_-_r_-__ ~~--.. +_-__ ~_-__ ~-4~~~4-~
5. 0 t---t--"~~~~-__ -1_ -_::::+--:-. _+_::_-+_--+-_::_:~---,~-=--=-~-=---~---+--+--+---!
4.0r; --r--T~~.--;--~--~-+--+--+--+--4--4-~~~~ "'l~
J.ac==c=-=c-~·-=rl-::!:~t~~~!~~~~~~~E:~=l==J--~1=~ ------ ---·-- -- - - · ----t--t---1-- +---+---+-- f------- -- -- - t--- t·---~
--~------ --- -·- ·-·!---~ ---
~ r--;---+---r---r--~--+---~~~-4--~--~--+---~~--~ 2.0 "' ...,
0
I
Cl)
"' ~ ()
--~- -·----- -·-- -- --- 1----f--t---1-- ----f-------------- ----· ·-- ---
~ 1.0 r--;---+---r---r--1---~--r-~~-4---+--~--+---+-~~-; (1)
Q
s::: Q) bD g
1---t-- --1- - -- ·--- -· --- ·-- c-- --- --· - ._
- --1-- --· 1--- -----·- --- r---- ,.-
---· --- --- --· --·--· -·- --- ··-- -- ··-
0.3 ---1---t--+----- ---
-f--·-t--t--+-----1--1- -- -- --1---1--
---r--- ---· ·--1---1---+--+---- ,__
1-----l-- --- --.---+-· ~·- --
--1-- --t---t----+--+--1--- 1---+---t--t--1--+--lf--
-·-- -- -- ----. - -+--
O.lL-~--L-~--L-~--~~--~~~~~~--~~~
0 2
Figure 19 . ...
4 6 8 10
Time, t, (miJil)
Dissolved Oxygen Deficit vs. Time for 600 ml/min/1 Aeration of Activated Sludge Containing LAS # 1
.._ · ' ,· •.
-) -.. +)
0
Cl) .. +) of"!
3.0
2.0
44
- --- ·---f--- ---
·-----·r--t--t--+--+--~--t---1--
·--~--4---~- ~
-1--+---~ -1----- 1---- -- f--- r-·
·- · ·--- 1----·
-- ----- ---- --- --~- f---- --1---
Bhnk C!)
- - ·-:l\ agl-l~ .___~--s:.~n •
-~~~11 -~ () 4:! 1. 0 r---t--r-t--t-+-t--t-+-+---t--+--l--+-+-~ Q)
0
s:: Q)
g --- -- --- ~- ---- ~-+--- --- --- --- ----- -· 1---l--'t1
Q) ~ 0.5 ~-t--+-~--4-~~~--~-+--+--+--~~--~--~~ 0 ~- -- 1-- --- -- ----- - ·- -- --- 1-·- --- 1--· ---'--l-It) It) 0.4 r-~r--t--~--~--~~---+--~--+---~-4--~--~--~~ E ------ f-·-- ----~--~---~---~--~-
0.3 r-~--r--r--r-~--~~~--4--4--~~--~~~ ·· - -- - ---r-- t---·-- -- - ,_____ --
1------- - --1----1---- -- -- ---1- -r------ --·- - -+-- -- . ---
0.2 r--+--r--+--+--+--+--+--4--4--4-~--~~--~~ ----- ----f----- - - ,------- ~
- · -- -- ---t---l--1----4--t---t--+--4--
·-- --·- -- ··-· ·-----'--
0.1 ~_. __ ._~--~~--~~--~~--~~~~~~~~
0 2
Figure 2_0.
4 6 8 10 14 " .·:.
Time, t, (miri~) Dissolved Oxygen Defi~it vs. Time for 300 ml/min/1
Aeratibn of A~tivated Sludge Containing Alfol
........ -c! If -.. +)
0
(/)
... · ..
45
---- f----- ---
3.0 ---f.---- -- -- ---j---t--t--l~-lr--1---f..--
--. '-'------- -- -- -- -- -- -1--·--'-
--f---f---- f---- ·'-- --1---1----·,
2.0 ·--1---- --f- - --
t---11----~--- ------ -- -
-- --- f---
0.8 r--r---t-t--t----1-+--+-l--+-+-4--+----+-+-~
------1--~--- --J..--- ,_ --- - f---
--- --·- ----- -- - --· ------· ---- --1----- ---'---- f---. ----
--+--- f-1--- ---- --- 1----·
0.3 r-~--r--r--r-~--~~~~~~~~-4--4-~~ ---+--+----
------· -- ---+---~------- 1--- -- ----. --1--1--
--t---- -- -- - -- -· --~-l--- ----1---- - --1--- -- ---
---t----- - --- -· - - r-- --1--- - --- --1--... --1--
1------1-- ---1-- +---1--+--+-- 1---+--1----
--- f----- --+--+--~-+--t---+----1
0.1 ·~~--~~~--~~--~~--~~--~~~--~~
. ·.:
0 2 4 6 8 10 12 14
Time, t, (mi.Ji~)
Figure ~1. Dissolved Oxygen Deficit vs. Time for 600 ml/min/1 Aeration of ~tivated Sludge Containing Alfol
:: ' .... /:~·~·:'~· .. ,·; .. .
46
-- f-----
., -- .. -- -- ----· . -- -·- ·-- - 1--t-- t - -t--t--lf--1---J--'-
- - ,.---- 1---- -- -- ---
3.0 --c! ~
------ ------- - -- - ---~---r---r--~--4----~--+------
-- --- ---t---1--- 2.0 .. +)
u -------:----1---Bl ink C!>
--- - ----- ---I
Cl}
----1---+------- --- --· --- - -- - 2 '- 'l!gif~I:--•-- c-----
---- _. __ __ ---_.!!.P811 A >-.AN, Dg}' l, 'IK: ..
~ (.)
~ 1. 0 r----t--t--t--t-+-+--+-+-~--J--+--+-~--+--1 Q)
0
r:: Q) bO g
---~--- 1-- ---- -
-----· -- 1- ------1-- - -- - -
0.3 ' -- - -1---1-- -- ----- f- -
----1----- ----- --- - - 1----------
-- -1---- --- ---- - ----- ------ ------ ----1---
0.2 r--+--~~~-+--+--4--~--~-+--4---~~--+--+--~ --- . ---1----t--+----- --~--1-- -- --
---- --~--1--- -----1-----f--1---
------ --------- - - ---1---+-- 1---+--t---1
0.1 ~~--~~--~~~~--~~--~~--~--~~--~~ 0 2
Figure 22 • ...
4 6 8 10 12 14
Time, t, (~~) Dissoived Oxygen Deficit vs. Time for 300 ml/min/1 Aeration of Aet~vated Sludge Containing Nalkylene
47
1o.or-~r~--~-r~--~-r--r-,--.--r-~~--r-~
a.·o ~~~~~-r-t--t--t--+--+-t-l-+-+--+---l---J \
6.0 ~ ----------
5.0 '~---t- lf-.J--
4.or-~~~~*~~r-,_-+--~~-4--+-~~--+-~~ "'~
- -- f--- ----
--f--- -
3.0 - ----r------- ----·- -· -----t---t--+--4--~-1..__--
~ llf
--1---... --1---'--1-- ---- ----1---<1---1--- - f----- - - - f---
..._, 2.0 ..
+) u ------f---- -- - --- --- ---J---1--+--
t--1--1·------ -- ----· ---
. __ . _____ ----.. +) ..-I ()
~ 1.0 r--1---t--~--t---r-~---t--4---+-~~-+--~--+---~~ Q)
Q
~ Q) bO g
---·- --1--..-- 11--- 1·- -f---- - - f-·-- --- - 1-- -· f--- -'t1 Q) ~ 0.5 ~-T--;---r--+--~--r--+--~--+--+--~--~-+--~~ 0 1-- ---1- ----· -· --·-- --f- -- - f-- -· II)
., 0.4 tS 1----1·-~--l------- --- f--
0.3 r--+--+--+--+--+--+-~--4--4--4-~--4-~--~~ -·. --- ·-- -- f-- -- --
-- --1- f--- -- -- --- -- - --~ ·--· ---- -- --1------
----- --- ---- -- ---- ------ -- f-- --f---- --
0.2 r--+--+--4~~--+-~--~--~-+--4---~~--+--+~ -1----1---- --- --'---· -- ---- ---
-- - - -- t---1----t-- 1--1---lr---~--4--- --- -- f-·-f--
Q.l ~~--~--~--~--~~--~--~--~--~~--~--~--~~ 0 2
Figur~ 23 . ....
4 6 8 10 12 14
Time, t, (mill~) Dissolved Oxygen Deficit vs. Time for 600 ml/min/1 Aeration of Act~vated Sludge Containing Nalkylene
48
VI. DISCUSSION OF RESULTS
A. Distilled Water System.
Comparison of Figures 6 through 11 shows that the higher rate of
aeration (600 ml/min/1) caused a more rapid approach to saturation than
did the lower rate of aeration (300/ml/min/1). The DO deficit, (s -C), t
of the "blank" at saturation decreased from approximately 0.33 mg/1 for
the lower rate of aeration to less than 0.1 mg/1 for the higher rate of
aeration.
The higher rate of aeration produced the following effects in
distilled water with the presence of detergents as compared to the
effects of the detergents in distilled water at the lower rate of
aeration. The 2 and 10 mg/1 concentrations of LAS #1 showed an in-
crease in DO deficit of approximately 0.1 mg/1 while the 5 mg/1
concentration showed a decrease of slightly less than 0.1 mg/1. The
10 mg/1 concentration of Alfo1 showed no significant change in DO
deficit for the increase in aeration rate, however, the 2 and 5 mg/1
concentrations showed increases of approximately 0.13 and 0.22 mg/1
respectively. The 2 mg/1 concentration of Nalky1ene decreased the DO
deficit by approximately 0.1 mg/1 at the 600 ml/min/1 aeration rate
as compared to the DO deficit for the same detergent concentration at
oxygen saturation for the 300 ml/min/1 aeration rate. The 5 mg/1
concentration of Nalkylene increased the DO deficit by approximately
0.03 mg/1. The 10 mg/1 concentration of Na1kylene caused no change in
DO deficit at apparent oxygen saturation.
In decreasing order of their overall effect in decreasing the DO
deficit over that of the "blank" in distilled water the detergents are
Nalkylene, Alfol, and LAS #1.
49
B. Tap Water System
It may be noted that the rate of approach to oxygen saturation, R,
did not differ greatly for similar aeration rates between the tap
water and distilled water systems with no detergent present. It may be
seen, however, that the "blanks" for the two systems reached saturation
with different DO deficits for the same rate of aeration. The "blank"
for the tap water showed an increase in DO deficit over that of the
distilled water amounting to 0.17 mg/1 and over 0.4 mg/1 for the 300
and 600 ml/min/1 aeration rates respectively.
Increasing the aeration rate from 300 to 600 ml/min/1 in the tap
water caused a more rapid approach to saturation. The increased rate
of aeration decreased the DO deficit of the "blank" from 0.5 mg/1 to
nearly 0.4 mg/1. The increased rate of aeration did not significantly
affect the DO deficits for the tap water containing the varying
concentrations of LAS #1 except as compared with the DO deficit of the
nblankrr for the same aeration rate. For the 600 ml/min/1 aeration ratE.
the difference in DO deficit at saturation between the "blank" and
detergent concentrations was approximately 0.1 mg/1 greater than it was
at 300 ml/min/1 aeration rate. The Alfol exhibited more consistency in
effects for varying detergent concentrations in the tap water at the
higher aeration rate. The 5 mg/1 concentration of Nalkylene exhibited
a notable effect on increasing the DO deficit at saturation from
approximately 0.35 mg/1 at 300 ml/min/1 aeration rate to 0.69 ml/min/1
at the 600 ml/min/1 rate of aeration.
In descending order of their effect on increasing the DO deficit
in tap water the detergents are LAS #1, Nalkylene, and Alfol.
C. Activated Sludge System
From Figures 18 through 23 it may be seen that all detergent
concentrations and "blanks" increased their rate of approach to
saturation when the aeration rate was increased.
50
The decrease in DO deficit for the "blank" which occurred with the
increased aeration rate in the activated sludge was comparable to that
which occurred for the distilled water (approximately 0.25 mg/1)
although the total DO deficits are not comparable. The decrease in DO
deficit for the increase in aeration rate for the tap water was less
(approximately 0.1 mg/1).
By comparing Figures 18 and 19 it may be seen that all
concentrations of LAS 4F1 caused a DO deficit in excess of the "blank"
at an aeration rate of 300 ml/min/1, whereas, at 600 ml/min/1 aeration
the 2 and 10 mg/1 concentrations of LAS #1 caused a DO deficit at
saturation less than that existing for the "blank."
From a comparison of Figures 20 and 21 it may be seen that in
creasing the aeration rate caused an increase in DO deficit of
approximately 0.5 mg/1 over that of the "blank" at saturation for the
2 and 5 mg/1 concentrations of Alfol while the curve for the 10 mg/1
concentration of Alfol nearly coincided with that of the "blank."
It may be seen by comparing Figures 22 and 23 that the comparative
changes in DO deficit were affected primarily by the change in deficit
for the "blank" at the different aeration rate. Except for the actual
decrease in DO deficit as measured from theoretical saturation for the
10 mg/1 concentration of Nalkylene the actual deficits of the 2 and 5
mg/1 concentrations remained nearly unchanged.
Of the three detergents studied the Nalkylene caused the least
detrimental effect on the oxygen transfer in the activated sludge.
D. Overall Oxygen Transfer Coefficient, ~a
In order to better understand the effects of the individual
detergents and their concentrations on the overall oxygen transfer
coefficient the values of ~a were determined in the following manner.
From the derivation of Equation 4,
-d dt s-et
= K la dt
the limits of C are reversed which eliminates the negative sign
preceding the integral.
or
log e
or
~a =
c 0
-d dt s-c
t
(s-c ) (s -c~) =
=~a
~a
(s-c ) 0
log e (s-et)
t
d t .••••••••••••••••••••
t
.....................
51
7 •
8.
S-C is the initial dissolved oxygen deficit when time, t, equals zero. 0
S-C is the DO deficit at time t. t
From the plots of DO deficit versus time, Figures 6 through 23, the
values of ~a were calculated for the initial straight-line portion of
the curves.
For example: Figure 7. ~a for 2 mg/1 of Alfol in distilled water
at an aeration rate of 300 ml/min/1.
~a=
log e
t
S-G0 \
S-C -~ =
log e
(8.38) (0.89) = 6
-1 0.374 min
The values of ~a were then plotted versus the detergent
concentration for each detergent in each liquid under the two rates of
aeration; Figures 24, 25, and 26.
From Figure 24 it may be seen that in the distilled water system
all three detergents caused a varying degree of decrease in ~a at the
lower concentrations. ~a for the 10 mg/1 concentration exceeded that
of the aerated distilled water without detergent for all detergents at
both rates of aeration •. The increase in rate of aeration from 300 to
600 ml/min/1 may be seen to have caused approximately a SO percent
increase in ~a·
From Figure 25 it may be seen that the initial ~a values for the
tap water system were approximately 0.05 units greater than they were
for the distilled water. As with the distilled water the lower
concentrations of detergent caused a decrease in ~a which then in-
creased for the 10 mg/1 concentrations of detergent. With the
exception of the ~a value for the Alfol at 600 ml/min/1 aeration, the
increases were not sufficient to raise the ~a values to those of the
blanks for the corresponding rate of aeration.
52
From Figure 26 it may be seen that no significant decrease in ~a
occurred from the presence of detergents in the activated sludge system
when aerated at 300 ml/min/1. A slight increase in ~a values may be
observed for all detergents as their concentrations increased during
this aeration rate. At an aeration rate of 600 ml/min/1 the presence
of LAS #1 and Alfol may be noted to have caused an initial decrease in
~a values over that of the rrblank", however, 10 mg/1 of Alfol caused
an increase in ~a· All concentrations of Nalkylene had ~a values
greater than that of the "blank"at the higher rate of aeration.
....... o.6 7
LAS #1 e e Alto1 ..__ _ _. Na.l.ky1ene >E--- -- -K
Aeration Rate a 600 ml/min/1
~ _0. 5 __ __....
.. ------~ --~ 0.4 .... ;:;;-:....,:;:;_;;::;~:::;:=:~:::;:::~---=-=i- - - - - -----1 -- ..:::= --t----=- -
Aeration Rate • 300 ml/min/1
o.o ~--~----._ __ _. ____ ~ __ _. ____ ~--~--~~--~--~ 0 1 2 3 4 5 6 7 8 9 10
Detergent Concentration, (mg/1)
Figure 24. KLa vs. Detergent Concentration in Distilled Water
0.3
0.2
0.1
LAS #1 E> G) Alfo1 4--- - --A Nal.ky1ene X- - - --~
Aeration Rate a 6oo ml/min/1 __ ____. ---__..---- ---------
--------- -----"..__ ___ .,____ _____ .. Aeration Rate • 300 ml/min/1
o . o ~--~--~~--~--~----._ __ _. ____ ~--~--_.--~ 0 1 2 3 4 5 6 7 8 9
Figure 25.
Detergent Concentration, (mg/1)
K vs. Detergent Concentration in Tap Water La
10
54
55
LAS #1 0 0 Altol .t. -~ Nal.ky'lene ~---- -K
Aeration Rate • 60o ml/min/1
------~--------~-------------~ --0.3
0. 1 Aeration Rate • 300 ml/min/1
0.0 ~------~--~----~--~--_.--~ ____ ._ __ ~---J 0 1 2 3 4 5 6 7 8 9 10
Detergent Concentration, (mg/1)
Figure 26. KL.Ys. Detergent Concentration in Activated Sludge
VII. CONCLUSIONS
The manner and extent of the effects of each detergent on the
three liquids under the two aeration rates studied have been discussed
in the preceding section. From this study the following conclusions
have been reached:
1. The detergents studied varied in the degree to which they
affected the dissolved oxygen deficit as compared to a
similarly aerated sample having no detergent content.
In descending order of their adversity to the DO deficit
for each system the detergents rank as follows:
a. Distilled Water - Nalkylene, Alfol, and LAS #1
b. Tap Water -LAS #1, Nalkylene, and Alfol
c. Activated Sludge -LAS #1, Alfol and Nalkylene
2. An unqualified statement as to the effect on ~a should
not be made for these detergents. For example, in Figure
24 it may be seen that ~a may be less than or greater than
that of the "blankn for different concentrations of the same
detergent. The degree to which ~a differs from that of the
"blank" may be affected by the rate of aeration. (Note the
Alfol in tap water, Figure 25)
3. The lower concentrations of detergent caused a decrease in
K_ which then increased for the 10 mg/1 concentration. -La
Eckenfelder and Barnhart (10) have reported similar effects
for sodium lauryl sulfate, NaLS04 , at a concentration of
25 mg/1.
4. An attempt at estimating the effects of detergents on ~a in
56
activated sludge based on ~a values for similar concentrations
of detergent and similar rates of aeration in distilled water
or tap water may lead to erroneous conclusions. For example
the increase in ~a over that of the "blank" caused by all
concentrations of Nalkylene in the activated sludge as com
pared to its effects in distilled water and tap water.
5. Based on the observed effects of these selected "soft"
detergents, a change in present aerobic wastewater treatment
is not necessary to satisfy the respiration requirements of
the microorganisms. This is evidenced by the fact that a
minimal dissolved oxygen concentration of 0.5 to 2.0 mg/1 is
usually required and over 4.0 mg/1 existed at equilibrium
in the activated sludge system.
6. While the increase of approximately 0.5 mg/1 in DO deficit
at saturation which occurs in two instances with the
activated sludge may not be critical in the treatment plant,
such a decrease in DO could be critical in a receiving body
of water already having a minimal DO content capable of
supporting fish life.
57
VIII • RECOMMENDATIONS FOR FUTURE STUDY
The following recommendations are made for consideration for
further studies.
1. The use of a magnetic stirring device or mechanical agitation
might be used to achieve the necessary velocity past the face
of the oxygen analyser probe. A recorder for the analyser
might also be considered.
2. Additional samples might be studied with particular emphasis
on their effects in the waste treatment processes and the
bodies of water which receive the effluents containing the
~d~.tddelt;ergfj!,llts .,, .
3. As a variation1 a shock loading of detergent might be applied
to see what effect the detergent has on a system already
saturated with oxygen.
58
59
BIBLIOGRAPHY
1. SAWYER, c. N. (1958) The effect of synthetic detergents on sewage treatment processes. Sew. and Ind. Wastes 30, p. 768-774.
2. McKINNEY, R. E. (1962) Microbiology for sanitary engineers. McGraw-Hill, New York, p. 223.
3. MANCY, K. H. and OKUN, D. A. (1965) The effects of surface active agents on aeration. Jour. Water Poll. Cont. Fed. 37, p. 212-227.
4. HOLROYD, A. and PAKRER, H. B. (1952) Investigations on the dynamics of aeration - the effects of some surface contaminants. Jour. and Proc., Inst. Sew. Purif. 4, p. 280.
5. MANCY, K. H. and OKUN, D. A. (1960) Effects of surface active agents on bubble aeration. Jour. Water Poll. Cont. Fed. 32, p. 351.
6. LYNCH, W. 0. and SAWYER, c. N. (1954) Physical behavior of synthetic detergents. I. Preliminary studies on frothing and oxygen transfer. Sew. and Ind. Wastes 26, p. 1196-1200.
7. LYNCH, W. 0. and SAWYER, c. N. (1960) Effects of detergents on oxygen transfer in bubble aeration. Jour. Water Poll. Cont. Fed. 32, p. 25-40.
8. MANGANELLI, R. (1952) Detergents and sewage treatment. Sew. and Ind. Wastes 24, p. 1065-1068.
9. ZIEMINSKI, s. A., GOODWIN, c. c. and HILL, R. L. (1960) The effect of some organic substances on oxygen transfer in bubble aeration. Tappi 43, p. 1029-1032,
10. ECKENFELDER, W. W. and BARNHART, E. L. (1961) The effect of organic substances on the transfer of oxygen from air bubbles in water. Amer. Inst. Chern. Engr. Jour. 7 ' p • 6 3 3 - 6 34 .
11.
12.
HANEY, P. D. (1954) Theoretical principles of aeration. Jour. Amer. Water Works Assn. 46, p. 353-376.
LEWIS, w. K. and WHITMAN, W. G. (1924) Principles of gas absorption. Ind. Engr. Chern. 16, p. 1215.~1220.
13 BRENNER T E (1966) Personal communication. . ' . . 14 KIRK J C (1966) Personal communication. . ' . .
15. LUDZACK, F. J. (1960) Laboratory model activated sludge unit. Jour. Water Poll. Cont. Fed. 6, p. 605.
16. ECKENFELDER, W. W., Jr. and O'CONNOR, D. J. (1961) Biological waste treatment. Permagon Press, New York, p. 42.
60
17. STANDARD METHODS FOR THE EXAMINATION OF WATER AND WASTEWATER (1960) 11th Ed., Amer . Pub. Health Assn., New York, p. 309-312.
61
VITA
Donald Ernest Modesitt was born at Richmond, Indiana on October
14, 1936 to Mr. C. Keith Modesitt and Mrs. Lorene May Modesitt. He
received his primary education at schools in Indiana, Michigan,
Illinois and Missouri. He graduated from Hannibal High School,
Hannibal, Missouri in May 1954. He graduated from the Missouri School
of Mines and Metallurgy (now the University of Missouri at Rolla) with
a Bachelor of Science Degree in Civil Engineering in May, 1958.
Mr. Modesitt has experience as a civil engineer with the highway
departments of Missouri and Illinois, and the National Park Service.
He was course supervisor of the Rod and Tape School, at Fort Leonard
Wood, Missouri while on active duty with the U. S, Army. Since
September, 1960 he has been an Instructor in Civil Engineering at the
University of Missouri at Rolla.
He is a registered professional engineer in the State of Missouri;
a member of the Missouri Society of Professional Engineers, American
Society of Civil Engineers, American Water Works Association, Missouri
Water Pollution Control Association, Chi Epsilon Civil Engineering
Fraternity, and Delta Sigma Phi Social Fraternity.
On October 10, 1959, Mr. Modesitt was married to Miss Linda L.
Rogers. They are the parents of three sons, Brian Dale, Keith
Bradley, and Paul David.
