1 11

U 1

QA COMPARISON OF QOXYGEN UTILIZATION DETERMINATION TECHNIQUES A

FOR THE ACTIVATED SLUDGE PROCESS.

Warren Michae1 Sta11ardThesis submitted to the Graduate Facu1ty of the

Virginia P01ytechnic Institute and State University

in partia1 fu1fi11ment of the requirements for the degree of

MASTER OF SCIENCE Vin

Sanitary Engineering

A _, 7 Q ___T, »7/ Q ,//' . -g/ ·‘ / "APPROVED: ~”;)¢.

Ran a11, Chairman·*"'"T" l V

/ /./ Q / y JP. H. King ~ @§}fH. Sherrard

September 19761

B1acksburg, Virginia

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_

ACKNDMLEDGEMENTThe

accomplishment of even so humble an effort as this paperC

T

represents is not often made without the aid and support of a number :L of the friends, the advisors, and the family of the author. This aid [

é[ and support is greatfully acknowledged. Although by no means [Lirepresenting all of the indiviuals who contributed to this effort the l

TTT

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TABLE OF CONTENTSACKNOWLEDGMENTS................................................iiTABLE OF CONTENTS.............................................iiiLIST OF FIGURES................................................ivLIST OF TABLES............................................. ...vi

I. INTRODUCTION....................................................lII. LITERATURE REVIEW...............................................3

Unified Design Approach.........................................36Coefficient Determination Methods...............................5Oxygen Transfer.................................................9Evaluation of Kla and Oxygen Utilization.......................lO

III. MATERIALS AND METHODS..........................................l4Wastewaters Tested.............................................l4 CAnalytical Proceedure..........................................22

IV. RESULTS........................................................24· Filtered COD Data..............................................24

Oxygen Uptake Rate Data........................................25Oxygen Utilization Data........................................28Other Data.....................................................28

V. DISCUSSION OF RESULTS..........................................53Oxygen Utilization Determination...............................53Consideration of Loading Factors...............................56Application of Oxygen Utilization Data to Design...............57

VI. CONCLUSIONS....................................................59REFERENCES.....................................................6lAPPENDIX.......................................................63VITA...........................................................67

iii

LIST OF FIGURESFigure l — Substrate Concentration asta Function of Time..........4

Figure 2 — Experimental Apparatus................................l7

Figure 3 - Variation in Oxygen Uptake Rate with Time for0.32 Initial Loading for Pulp and Paper waste.........30

Figure 4 - Variation in COD Removed and Oxygen Utilizedwith Time for 0.32 Initial Loading for Pulpand Paper waste.......................................3l

Figure 5 - Variation in Oxygen Uptake Rate with Time for0.44 Initial Loading for Pulp and Paper Waste.........32

Figure 6 — Variation in COD Removed and Oxygen Utilizedwith Time for 0.44 Initial Loading for Pulpand Paper waste.......................................33

Figure 7 - Variation in Oxygen Uptake Rate with Time forl.79 Initial Loading for Pulp and Paper waste.........34

Figure 8 — Variation in COD Removed and Oxygen Utilizedwith Time for l.79 Initial Loading for Pulpand Paper waste.......................................35

Figure 9 - Variation in Oxygen Uptake Rate with Time for0.25 Initial Loading for Textile waste................36

Figure l0 - Variation in COD Removed and Oxygen Utilizedwith Time for 0.25 Initial Loading forTextile waste.........................................37

Figure ll - Variation in Oxygen Uptake Rate with Time for0.49 Initial Loading for Textile waste................38

Figure l2 - Variation in COD Removed and Oxygen Utilizedwith Time for 0.49 Initial Loading forTextile Waste.........................................39

iv

A lLl

Figure l3 — Variation in Oxygen Uptake Rate with Time for0.6l Initial Loading for Textile waste................40

Figure l4 - Variation in COD Removed and Oxygen Utilizedwith Time for 0.6l Initial Loading forTextile waste.........................................4l

Figure l5 - Variation in Oxygen Uptake Rate with Time for0.0l4 Initial Loading for Domestic waste..............42

_ Figure l6 - Variation in COD Removed and Oxygen Utilizedwith Time for 0.0l4 Initial Loading forDomestic waste........................................43

Figure l7 - Variation in Oxygen Uptake Rate with Time for0.029 Initial Loading for Domestic waste..............44C

Figure l8 - Variation in COD Removed and Oxygen Utilizedwith Time for 0.029 Initial Loading forDomestic waste........................................45

Figure l9 — Variation in Oxygen Uptake Rate with Time for0.047 Initial Loading for Domestic waste..............46

Figure 20 - Variation in COD Removed and Oxygen Utilizedwith Time for 0.047 Initial Loading forDomestic waste........................................47

Figure 2l - ln(CS-Ct) versus Time for 0.44 Initial Loadingg for Pulp and Paper waste for Endogenous Uptake

Rate and Blok—Benefield Kla Calculation...............52

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LIST OF TABLES

Table l-Characterization of Pulp and Paper wastewater................l5

Table 2-Characterization of Textile wastewater.,.....................20Table 3-Characterization of Domestic wastewater......................23Table 4-Initial and Final MLVSS and COD Concentrations...............48

Table 5-COD Removal and Stabilization Data...........................49

Table 6-Percentage of Theoretical Oxygen Utilization forEach Method of Oxygen Utilization Determination..............50

Table 7-Kinetic Coefficients Calculated from Mass BalanceData for Each Experiment.....................................5l

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I INTRODUCTION

Associated with the discharge of untreated wastewaters to streams

are a number of pollutants. The pollutants most commonly removed in

treatment are unoxidized organic and nitrogen compounds in the discharge.

These compounds act as a food source for aerobic microorganisms present

in the stream water, requiring large amounts of oxygen for metabolism

and often completely depleting the supply of oxygen dissovled in the

water. Because of this lack of oxygen, other aqueous fauna, such as

fish, crustaceans, etc. are unable to exist. Anaerobic conditions

develop, accompanied by unpleasant odors, a black color, and septic

conditions in the water.

Probably the most commonly used method for treatment of wastewaters

for removal of oxygen demanding pollutants is the activated sludge

treatment process. This is a biological process in which an attempt

is made to duplicate and concentrate the conditions that esist in the

stream. The waste is placed in a tank containing a very large con-

centration of aerobic microorganisms. Oxygen, usually in the form of

air, is introduced into the mixed liquor by mechanical agitation or bubble

aeration. The microorganisms remove the organic material from the waste-

water by metabolism, with accompanying new microbial growth.

This metabolic process, whether occurring in a stream or an activated

sludge treatment facility, may be described by the following simplified

equation:

l

I2 I

0R6AII1c MATTER + 02 + IIH3 NEW IOTHER NUTRIENTS I

IIIMICROBIALMASS + CO2 + H20 + NO3As can be seen in this equation, however, the consideration of oxygen

is basic to the process. The fact that the process is termed aerobic

implies that it will not proceed in the absence of available oxygen. The

organic strength of wastewaters is most often measured in terms of the

oxygen demand it can exert.

In addition to the oxygen required to stabilize the organics in a

water, a surplus of reduced nitrogen in the waste can be expected to

exert an oxygen demand of its own. Nitrogen is required in the synthesis

of new cellular mass but the excess, under favorable conditions, will be

oxidized to the nitrate form. This process is known as nitrification.

Design of treatment facilities for a wastewater is typically based

upon certain kinetic coefficients evaluated for that particular waste.

Evaluation of these constants by a batch reactor approach makes large

use of oxygen uptake data. Continuous flow reactor experiments yield

coefficients based on changes in organic strength and measured microbial

mass production. There are a number of methods available for calculating

oxygen uptake. The purpose of this paper is to examine and compare a

number of these methods, and to test the applicability of the obtained

data to evaluation of kinetic coefficients. VIII

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I

II. LITERATURE REVIEW I

UNIFIED DESIGN APPROACHESThe activated sludge treatment process and its variations have

been used for several years in treating wastewaters. Only in recent years,

however, have mathematical models been developed that make design and

operation of these facilities at least something of a science. Probably

the two most commonly used of these models are the McKinney and

Eckenfelder model (l) and the Lawrence and McCarty model (2) which apply

to completely-mixed systems.

McKinney agg_Eckenfelder Ngdgl„ McKinney and Eckenfelder developed

independently what has been shown by Goodman and Englande (l) to be the

same model. Its primary assumption is that the rate of organic removal in

an activated sludge system is first order. Such an assumption yields a

graph of organics remaining versus time similar to that shown in Figure l.

This approach was used to develop a model which relates organic removal

to aeration tank mixed liquor volatile suspended solids (MLVSS) and

aeration tank detention time. Performance of the system was found to

be a function of organic loading and sludge age (3).

Lawrence and_McCarty Ngggl„ In the early l940's, Monod (4) published

data indicating that substrate concentration and biological growth rate

are related by the equation,

(2)where:

ää-= rate of microbial substrate utilization per unit time, mass

per volume-time;

3

4

SE-•—>¢¤L+’ ~ .g 2, Monod Equation —g ’ RemovaiOLJ

¢¤L T+° .U) TD .3(/7

_ FirstOrder

Zero RemovaiOrderRemovai __„_w _

Time, t ——•·

Figure T- ‘ Substrate Concentration as a Function of Time.

5

k = maximum rate of substrate utilization per unit weight of

microorganisms, time-];

S = concentration of substrate surrounding the organism, mass

per volume;

KS = substrate concentration when gg-= äk, mass per volume;X = microbial mass concentration, mass per volume.

A plot of this equation is shown in Figure l. It can be seen that when

S<<KS, the equation approaches first order. when S>>KS, the equation

approaches zero order. From this basic equation, Lawrence and McCarty

(2) developed a unified design approach based upon solids retention

time or sludge age.

COEFFICIENT DETERMINATION METHODS

Before either of these models may be applied to design of waste

treatment facilities, certain kinetic coefficients must be evaluated.

In the case of industrial wastes, for which the characteristics are often

not as well known as for domestic sewage, this usually involves conducting

lab or pilot plant experiments, the data collected being subsequently

used to calculate the desired coefficients (l,3,5). These experiments

often require operating continuous flow reactors, usually for long

periods of time.

Batch Reactor Method. Meston and others have proposed that suffi-

cient data for evaluation of these cofficients can be collected over a

short period of time using batch, rather than continuous flow experiments

(6,7,8). order plot, also shown in Figure l. From mass balance and

stoichiometric considerations, sludge production and substrate removal

rate are related to chemical or biochemical oxygen demand and oxygen

l

6utilizationdata. V

Oxygen utilization within this batch reactor system was an important

parameter to these researchers. They theorized that removal of COD from

solution may or may not occur at the actual rate of stabilization, Removal

represents only a transfer of organic material into the cell, where it will

continue to exert an oxygen demand as actual oxidation or stabilization

occurs. They stated that this oxygen uptake time can never be less than

removal time, since COD must be transferred before it can be oxidized.

For this reason, the weston group proposed that the time at which COD

removal, or transfer, is complete not be used to calculate ths substrate

utilization rate. Instead, they contended the actual time required for

stabilization, represented by the time to complete oxygen uptake, should

be used.

Open Respirometer Methods. Expanding upon the concepts proposed

by weston, Blok (9) has argued that much usable information may be

obtained from oxygen utilization data, alone. He has classified batch

experiments as being either short term or long term. Short term

experiments were defined as having high MLVSS concentrations, extremely

low initial loading factors, and very short completion times, usually

from 3O to 6O minutes. Blok defined long term experiments as having

higher initial loading factors and longer completion times. For the

short term experiments there was no appreciable change in MLVSS con- Ecentration, while the long term experiments were characterized by large

initial increases in MLVSS concentration, followed by virtually Ä

complete solids destruction. Blok attempted to confine his experiments (

to the short term variety, since these conditions allowed a number of Vsimplifying assumptions. Ä

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Using an open resirometer technique, he investigated the effects I

of substrate and sludge concentration and characteristics on oxygen utili-

zation, and evaluated surplus sludge formation using a series of batch

experiments. Blok warned, however, that the longer the completion time

for the experiments, the less applicable were his methods. He therefore

proposed that open respirometer investigations be confirned to short term

experiments.

In evaluating surplus sludge formation, Blok proposed that a mass

balance must exist within the reactor between the quanity of oxygen

utilized, oxygen demanding material removed, and change in microbial mass.

He therefore subtracted the quantity of oxygen utilized, less calculated

nitrogenous oxygen demand, from the quantity of COD removed to obtain

sludge production values. The experiments consisted of a series of short

term batch reactor runs made by loading the same reactor with several

separate slugs of substrate. The values for sludge production obtained

agree very well with measured values.

Benefield, Randall, and King (lO) have proposed that Blok's open

respirometer technique can be applied to longer range batch experiments

and combined with Weston's equations to yield a variety of design

values. Since the rate of substrate metabolism is proportional to

oxygen consumption, the rate and order of removal may be obtained from

oxygen utilization data. Cell maintenance and yield coefficients may be

obtained in the following manner:(AX

= (COD)removed - (02)utilized (3)l.42

where

„„__„_______(

AX = change in biomass concentration

= chemical oxygen demand removedI I

(O2)Uti1iZed = oxygen utilized to metabolize the COD removedIt should be noted that must include the endogenous oxygenrequirement whether microorganisms oxidize a portion of external substrate

to satisfy maintenance energy requirements as proposed by Pirt (ll), or

oxidize cellular mass as proposed by Herbert (12).

Kcfiäät (4)where:

Kd = maintenance energy coefficient

R = endogenous respiration rate

X = biomass concentration

Yt° removedwhere:

Yt = true yield coefficient

Benefield, et al. (10) using the relationship,

&=aä%+bX (6)At

where:AO2 = total oxygen requirement of the biomass over some time

interval At „ IX = biomass formed over some time interval At Ia = oxygen required to form a unit of biomass Ib = oxygen required per unit of biomass for the maintenance of I

life per unit time I

1 1

AS = quantity of COD removed over time interval At

have proposed that

1. b =§— (7)and 2_ (8)OXYGEN TRANSFER

It is generally accepted that the transfer of oxygen from a gaseous

to a liquid solution is best described by what is known as the "two-film

theory", proposed in l924 by Lewis and whitman (l3,l4,l5,l6). According

to this theory, boundary films form at the interface within both the liquid

and the gas. The rate of diffusion through the films depends on the area

of the interface and the concentration gradient within the films. In the

case of gases of low solubility, such as oxygen, the differential equation

for the rate of gas transfer into the liquid becomes:

9:% = 1<]a (cs - ct) (9)where

gg-= the rate of transfer at time, tK] = a proportionality constant related to overall conductance

a = the interfacial area

CS = the saturation concentrationCt = the concentration at time, t

Neither K] nor a can be evaluated directly as a rule, so they are usually

evaluated and expressed as a product, K]a (l4).

The foregoing discussion has been of oxygen transfer into a liquid

l0

in which no microbial activity is occurring. lf there is no purely chemical

oxygen demand to be satisfied, the liquid being aerated will eventually

reach saturation and the rate of oxygen transfer will drop to zero.

However, if there are viable aerobic microorganisms present, respiration

of these organisms will exert an oxygen demand and the resulting rate of

oxygen transfer will be equal to the rate of oxygen usage by the

microbial mass (9,lO,l4,l7).

The rate of oxygen transfer for a mixed liquor being aerated may be

expressed as

ä%= 1<]a (CS - Ct) — R (10)where

R = rate of oxygen utilization for endogenous conditions.

Under endogenous conditions, the rate of oxygen utilization and, conse-

quently, the rate of oxygen transfer become essentially constant for

finite time periods and the dissovled oxygen concentration becomes

constant. Therefore,

gg-= O = K]a (CS - Ce) - R (ll)or

R = 1<,a (CS - CE) (12)where

Ce = the equilibrium dissolved oxygen concentration for endogenous

conditions.I

Ä

EVALUATION OF Kla AND OXYGEN UTILIZATIONSeveral methods have been proposed for the determination of oxygen

utilization within an activated sludge system (9,l0,l4,l5,l8). Except for

11 1

those methods which are not dependent upon direct measurement of oxygen

uti1ized, such as the Warburg device, a11 invo1ve the use of oxygen uptake

or transfer rate, the two being equiva1ent (14,17). A11 but one of these

methods require eva1uation of Kla. The one exception re1ies upon direct

measurement of uptake rate (18).

As has been stated previ0us1y, the oxygen transfer rate, in the

absence of an immediate chemica1 oxygen demand, must be equa1 to the

rate of bio1ogica1 oxygen uti1ization and proportiona1 to the rate of

substrate uti1ization (17). When this rate is p1otted as a function of

time, the area under the resu1ting curve is equa1 to the quantity of

oxygen uti1ized.

The constant Kla is known to be a function of severa1 system vari-

ab1es. Among these are temperature, the degree of mixing, 1iquid depth,

and waste characteristics (15,17). Because there are so many variab1es

invo1ved, K1a is virtua11y impossib1e to ca1cu1ate and must be eva1uated

experimenta11y.

a - 6 METHOD. The se1ection of aeration equipment for activated

s1udge systems is most common1y based upon eva1uation of oxygen transfer

rate by what may be ca11ed the a - 6 method (15,18). The constant, a,

is defined as the ratio of the K1a for the waste to the Kla for water.If the oxygen transfer equation

ä·%= ·<1¤ (C.-

Ca (91is so1ved for C as a function of t, it becomes

E;-{lg? = Kla at (131(cs - ct) = -1<]a1;. (111

T2 IKla for water is determined by removing oxygen from a sample of water by

chemical addition or nitrogen stripping. The water is then reaerated while

DO concentration is monitored as a function of time (T5,l8). The natural

logarithm of the oxygen deficit, CS - Ct, is then plotted versus time.

The slope of the resulting line is equal to -K]a.

Kla for the wastewater is determined in exactly the same way using a

mixed liquor sample of the same concentration of MLVSS as will be used in

the system. Calculation of Kla is as described for pure water. B repre-

sents the ratio of the DO saturation value for the waste to that of water.when these values have been evaluated in the lab, a K]a for the

actual reactor vessel, whether a lab scale batch reactor or an aeration· basin, is obtained using pure water. This determination is made by the

methods described above, carried out in the reactor vessel. The follow-ing equation is then used to determine the uptake or transfer rate:

(ßcs - ct)where:

Kla is that for pure water in the reactor vessel (T8).

This method has, however, been reported by Busch (T7) and Ford and

Eckenfelder (T9) to give unsatisfactory results. In addition, for Tab

scale experiments, it seems particularily inappropriate, since a K]a for

the waste must be evaluated anyway and the determination may be made in

the reactor vessel using a waste and microbe sample without considering

the Kla for water at all.NON-STEADY STATE METHOD. Eckenfelder (T5) has proposed that Kla be

evaluated using waste and microbial mass under actual operating conditions

is Tin the reactor vessel. Dissolved oxygen is removed by addition of sodium

sulfite with a catalyst of cobalt chloride. The reactor is then mixed and(

reaerated while DO concentration is monitored. Since

gg-= Kla (CS - Ct) -R, (10)

(T6)If the change in concentration with time is plotted versus the concentra-

tion of DO, the slope of the resultant line is equal to -K]a and the

intercept equal to (K]a CS - R).

Benefield (TO) and Blok (9) have proposed that this method may be

used for a reactor whose contents are endogenous, and the natural

logarithm of the DO deficits obtained may be plotted versus time to

yield a line whose slope is equal to -K]a.

STEADY STATE METHOD. Eckenfelder (T5) has also proposed that K]a

for a reactor whose contents are endogenous may be determined by the

following equation,Kia = (T7)

if the endogenous respiration rate, R, is known.

DIRECT MEASUREMENT METHOD. It has been proposed that determination

of Kla is unnecessary to the calculation of oxygen utilization (T8).

The oxygen uptake rate may be determined directly by placing a 3OO ml.

aerated sample of the mixed Tiquor in question in a BOD bottle. As the

DO concentration begins to fall in the bottle, the concentration is

recorded at various time intervals. DO concentration is then plotted Tversus time to yield a straight line whole slope is equal to

theoxygenuptake rate (T8).

T

III. MATERIALS AND METHODS EExperiments were conducted with three different wastewaters to test T

the agreement and applicability of oxygen uptake rate determination

methods. The wastewaters used were a pulp and paper waste, a textile

manufacturing waste, and a municipal waste. For data collection, each

of these wastes was added to a batch reactor containing microorganisms

that had been acclimated to that particular waste. Chemical oxygen

demand (COD) and dissolved oxygen (0.0.) concentrations, pH, and oxygen

uptake rates were then monitored either periodically or continuously (

until the oxygen uptake rate returned to what it had been before the

waste was added. Each waste was run in this manner at three different

loading conditions.

NASTENATERS TESTED

Pulp and Paper Waste. The first waste tested was that from a pulp and

paper mill utilizing the sulfite pulping process. The wastewater was col-

lected from the treatment plant influent, immediately following screens

where large cellulose fibers were removed. It was characterized by a

total solids concentration of 6000 mg/l and a suspended solids concentra-

tion of 3000 mg/l. Despite this high colloidal content, however, the

biochemical oxygen demand (BOD) of the filtered waste was very close

to that of the unfiltered waste, indicating that this colloidal matter

was, for the most part, non-biodegradable. COD for the waste was

approximately 5000 mg/l. pH was found to be 7.0.

After collection, the waste was stored at 4°C until used. Activated

sludge obtained from the Roanoke, Virginia, waste treatment facility was

acclimated to this waste for ten days at 20°C in a continuous flow reactor

The refrigerated waste was allowed to warm to 20°C and nitrogen and T

l4

III

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Table l- Characterization of Pulp and Paper Wastewater

Parameter Concentration

Unfiltered COD 4430 mg/l

Filtered COD 3059 mg/l

% Colloidal COD 3l%

Unfiltered BOD5 l860 mg/l

Filtered BOD5 I833 mg/l

Total Solids 6000 mg/l

Total Volatile Solids 3350 mg/l

Suspended Solids 3000 mg/l

Volatile Suspended Solids 2700 mg/l

III

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16

phosphorus were added before it was fed to the microbial reactor.

Upon completion of the ten day acclimation period, flow to the reactor2

was halted and the mixed liquor allowed to enter endogenous respiration.

A batch reactor with a liquid capacity of 3-l/2 liters was set up at this

point. Figure 2 is a diagram of the unit. A DO probe, Y.S.I. model 54,

was introduced through the side of the unit at approximately l/4 of the

reactor height above the base. A sampling port was located at the base

of the reactor. For each wastewater, the reactor was loaded with three

different ratios of waste to mixed liquor volatile suspended solids (MLVSS)

concentration during separate experiments.

THE MLVSS concentration in the acclimation reactor was determined and

sufficient mixed liquor was transferred to the batch reactor to provide the

desired mass of volatile suspended solids for each run. Supernatant from

the acclimation reactor was added to provide 3-l/2 liters of mixed liquor.

The contents of the batch reactor were then aerated to an equilibrium

dissolved oxygen concentration. Three hundred milliliters of mixed liquor

were then withdrawn from the reactor and placed in a BOD bottle. A dis-

g solved oxygen probe was inserted into the bottle and the DO decline

recorded. The concentration was plotted versus time to obtain an oxygen

uptake rate. The rate was assumed to be the endogenous oxygen uptake rate.

After the oxygen uptake rate was measured, the three hundred

milliliter sample was returned to the batch reactor and the DO concentration

allowed to drop to a very low value by turning off the compressed air. The

reactor was then reaerated, and the DO rise monitored by the DO probe

inserted in the reactor. This probe was connected to a YSI model 54 dis-

solved oxygen meter and the data recorded on a Sargent—welch model SRG

I

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17

CompressedAir

3.5 LiterReactor Vesse1 Ils. Q-3 Ive-

Q. D. Probe/ Stirrer

Il4 IIIIIIIIIIIIM ‘

{__ ÄTo D. 0. Meterand Recorder

gMagnetic

Stirrer

Figure 2- Exoerimenta1 Aboaratus.

l8recorder.After the DO in the batch reactor had returned to its T

equilibrium value, the reactor contents were allowed to settle.Three different experiments were performed with the pulp and paper

waste. For what was called the "standard" run, a MLVSS concentration ofapproximately 3000 mg/l was used. The 3.5 liters of sludge and super-

natant were settled toone liter, the supernatant withdrawn, and 2.5 liters

of waste added. For the "l/2 standard" run, MLVSS concentration of 3000

milligrams per liter was again used. Reactor contents were settled to

2.25 liters and l.25 liters of waste added. In the case of the "l-l/2

standard" run, the MLVSS concentration was dropped to 2000 milligrams

per liter and the same procedure as for the "standard" run followed.

Before the waste was added to the reactor, a complete solids charac-

terization was made. In addition, COD and BOD samples were collected

and analyzed. COD and BOD samples of the reactor supernatant were also

withdrawn. The waste was then aerated to the same D0 concentration aswas equilibrium during endogenous operation.

Immediately after the wastewater was added to the batch reactor,

a 400 ml sample was withdrawn, aerated, and pH monitored in this reactor.

AAFisher model 230 pH meter was used connected to a Bausch and Lomb model

VDM-7 recorder. (pH monitoring in a separate sample was found to be

necessary because of electrical interference between the pH meter and

the DOprobe.)At

the same time that the 400 ml sample was withdrawn, an additional

sample was taken from the reactor and a suspended solids determination made

of the reactor's contents. At the following times after loading of the

l9 ‘T

reactor, additional samples were withdrawn: l, 5, l0, l5, 20, 25, 30, 40, ]50, 60, 75, 90, l05, l20 minutes, and at 30 minute intervals after thatuntil the oxygen uptake rate returned to its endogenous value where the

run was considered to be complete.

At each sampling time, a 300 ml sample was withdrawn and placed in a

BOD bottle, and the drop in the D0 in that bottle monitored as described

previously to obtain an oxygen uptake rate. The sample was then returned

to the reactor. In addition to the 300 milliliter sample, a smaller

sample was removed at the same time. This smaller sample was filtered

through a Kimwipe tissue followed by a No. 4 whatman filter to approxi-

mate settling. A COD and a BOD sample were prepared from the filtrate

and the remainder passed through a 0.45p Millipore filter. Again, a

COD sample was prepared from this filtrate. This was referred to as

the "filtered COD". That sample which had gone through only the No. 4

whatman filter and the Kimwipe was called the "settled COD".

Throughout each run, the dissolved oxygen concentration in the reactor

was continuously monitored. The DO probe was a YSl model 54. The DO data

were recored on a Sargent-welch model SRG recorder. At the end of each

run, a new suspended solids determination was made.

Textile Waste. A Cellulose manufacturing wastewater was chosen as

an example of a simple organic substrate low in suspended matter. This

particular wastewater was found to have a total solids concentrationof6000mg/l of which only 30 mg/l was suspended solids. The COD was l80O :

mg/l and the BOD was approximately l70O mg/l illustrating that it was‘

readily biodegradable. The initial pH of this waste was 4.5.The treatment facility at the manufacturing plant where the ‘

20

Table 2- Characterization of Textile wastewater

Parameter Concentration

Unfiltered COD l56O mg/l

Filtered COD l460 mg/l

% Colloidal COD 6.5%

Unfiltered 3005 ll75 mg/l

Filtered BODS l040 mg/lC

Total Solidsl

6200 mg/l

Total Volatile Solids 2600 mg/l

Suspended Solids 35 mg/l

Volatile Suspended Solids 099-

22inthe manner described for the pulp and paper waste. Upon removal of the _

supernatant, the remaining reactor contents were stirred and one seventh of

the volume placed in the small DO monitor reactor. One seventh of the (

aerated waste volume was added to this reactor and six sevenths to thelargereactor

simultaneously. The experiment then progressed just as for the

previously described pulp and paper waste runs. In the case of the textile

waste, however, COD samples were not filtered through a Kimwipe tissue and

no BOD samples were taken.

Domestic waste. For the experiments using domestic wastewater, primary

influent, after grit removal and grease removal, was collected from the

Blacksburg, Virginia, trickling filter plant. Sludge from a rest stop on

Interstate 8l was acclimated to this waste for ten days in a continuous

flow reactor. The waste was obtained fresh each day. Characteristics of

the waste used in the experiments are shown in Table III. The procedure

followed during the run was identical to the procedure described for the

pulp and paper waste except that samples were not filtered through tissues

prior to the whatman No. 4 filter, and nutrients were not added.

ANALYTICAL PROCEDURE

A number of tests were used in conducting these experiments. ATT solids

determinations, including total solids, dissolved solids, both volatile and

fixed, and suspended solids, volatile and fixed, were made in accordance

with the "Residue" section of Standard Methods jor_the_AnaTysis gj_wgstg_and

wastewaters, l4th Edition, (T8) utilizing gooch crucibles and glass filters.

Chemical Oxygen Demand and Biochemical Oxygen Demand determinations were

also done in accordance with Standard Methods. ATT other tests were ämade as describedabove.Y

"YAAA‘‘——

23 Ä

Tab1e 3- Characterization of Domestic wastewater

Conc. forConc. for 1/2 and 1 1/2

Parameter Standard Run Standard Run

Unfi1tered COD 253 mg/1 217 mg/1

Fi1tered COD 152 mg/1 86 mg/1

% Co11oida1 COD 40% 60%

Unfi1tered 8005C

132 mg/1 1 147 mg/1

Fi1tered 8005 106 mg/1 119 mg/1

T0ta1 So1ids 498 mg/1 530 mg/1

Tota1 Vo1ati1e So1ids 200 mg/1 220 mg/1

Suspended S01ids 90 mg/1 97 mg/1

Vo1ati1e Suspended So1ids 60 mg/1 62 mg/1

IV RESULTS i

The data collected during the series of experiments of this investi-

gation included: COD data for both settled and dissolved samples, BOD data

for settled samples for certain of the experiments, reactor dissolved

oxygen concentration, pH, and oxygen uptake rates. Problems encountered

during the collection of settled samples, e.g. loss of vacuum and resultant

release of filter suction accompanied by contamination of the sample with

microbial material, led to the decision to omit settled COD and BOD results.

During each of the experiments, pH varied so little that nothing could be

gained by its inclusion, either. The results of interest for these experi-

ments are shown in Figures 3 through 2l and in Tables 4, 5, 6, and 7.

Loading factors were calculated as total COD removed divided by initial

microbial solids concentration as measured by MLVSS.

FILTERED COD DATA

The COD data presented are from those samples which were filtered

through a 0.45 filter. Since this is generally accepted as the dividing

point between molecular and colloidal particle size, the COD information

represents only dissolved COD. The data is shown plotted as COD removed

versus time. For the pulp and paper waste, results are shown in Figure 4

for the 0.32 loading, in Figure 6 for the 0.44 loading, and in Figure 8

for the T.79 loading. For the textile waste, COD data for the 0.25

loading are shown in Figure TO, for the 0.49 loading in Figure T2, and

= for the 0.6l loading in Figure T4. Data for the domestic waste are shown T

for the 0.0l4 loading in Figure T6, in Figure T8 for the 0.029 loading, Z

and for the 0.047 loading in Figure 20. i‘ 24 Z

25 Il

OXYGEN UPTAKE RATE DATADIRECT MEASUREMENT METHOD. During the course of each of the experi-

ments, a sample of mixed liquor was drawn from the reactor periodically.

Its dissolved oxygen concentration was determined as a function of time

and the obtained values were plotted versus time. Slope of the straight

line which best connected at least three of the points was taken as the

oxygen uptake rate.(

BLOK-BENEFIELD STEADY STATE METHOD. A K1a value for the waste andreactor was obtained using the method outlined by Blok (9) and Benefield(lO). Aeration of the reactor containing an endogenous mixed liquor

was halted and the DO concentration allowed to drop to an arbitrary low

value. Aeration was resumed and the DO concentration was monitored asa function of time. The slope of the line obtained by plotting the

natural logarithm of the DO deficit, CS - Ct, versus time was taken tobe K1a for the reactor. This K1a value was multipled by the DO deficitat any time, t, in the course of the run to yield the oxygen uptake rate

at that time.

AVERAGED METHOD. If the oxygen uptake rate equation,

gg: I<1a ms - cp <¤>is used in conjunction with known values of oxygen uptake rate, K1a may

be calculated by the following equation

Kla = oxygen ugiakecrate (18)

Values of oxygen uptake rate at various times in the course of each run

were known from the data of the direct measurement method described above.Since DO concentration in the reactor vessel was monitored continuously,

26 EDO deficit information was available for each of these times. Between 2

5 and lO times during each run were arbitarily chosen for which direct

measurement uptake rates were known and K]a values calculated for eachtime. These K]a values were then averaged and the resulting K]a usedto obtain the graphs marked as "Averaged O2 Uptake Rate".

MASS BALANCE METHOD. The Law of Conservation of Mass must hold forthe experimental system. Therefore, the total oxygen utilized must

equal the chemical oxygen demand removed less that portion of COD

that goes to sludge production plus the oxygen utilized in satisfying

nitrogeneous oxygen demand, and the quanity of oxygen which goes to

satisfy cellular maintenance requirements. The cellular maintenance

requirement term does not play a part in calculation, however. whether

the cell maintenance energy requirements are satisfied by metabolism

of substrate or by metabolism of cellular mass is of no consequence to

this balance. If the requirements are satisfied by metabolism of

substrate, the oxygen requirements are reflected in the COD metabolized

term (COD removed minus COD incorporated in new microbial mass). If

satisfied by metabolism of cellular mass, the mass balance equation may

be written as:

(O2)utilized =(COD)removed+

(NOD) + CELL MAINTENANCE OXYGEN.

The change in microbial mass is, however, an apparent change. The

quanity of mass oxidized to satisfy maintenance energy requirements

must be replaced before any net increase is noted. Therefore,

1 27 1

CHANGE IN MICROBIAL MASS = APPARENT CHANCE IN MICROBIAL MASS I+ (1.42 x CELL MAINTENANCE OXYGEN) (20)

1.42 is simp1y a conversion factor for expressing ce11u1ar mass in terms of

oxygen demand (5 ). Substituting this expression into the mass ba1ance

equation yie1ds:

(02)uti1ized = (C0D)removed

- (APPARENT CHANGE IN MICROBIAL MgSS)+(1.42 x CELL MAINTENANCE OXYGENQ+ (NOD) + CELL MAINTENANCE OXYGEN (21)This reduces to (APPARENT CHAN$E4éN MICROBIAL MASS)

+ (NOD) (22)It shou1d be noted that the change in so1ids concentration need not a1ways

be an increase for this ba1ance to ho1d true.Based upon this argument, a KIa for the system was determined in the

fo11owing way:

1. Assume KIa = 1.0. Ca1cu1ate oxygen uptake rate as described

for the B1ok-Benefie1d method.2. Obtain the quanity of oxygen uti1ized by taking the area

under the curve of oxygen uptake rate versus time.

3. Ca1cu1ate the quanity of oxygen theoretica11y uti1ized from:

(02)THE0RETICALLY UTILIZED+noo (23)

4· KIa = (32)THEORETICALLY UTILIZED I2)UTILIZED FROM (2) ABOVE I

28 i

Oxygen uptake rate was calculated from this K]a as described previously. 4

The oxygen uptake rates as a function of time are shown for the 0.32

loading of pulp and paper waste in Figure 3, for the 0.44 loading in

Figure 5, and for the l.79 loading in Figure 7. For the textile waste,

oxygen uptake rate data are shown for the 0.25 loading in Figure 9, for

the 0.49 loading in Figure ll, and in Figure l3 for the 0.6l loading.

Domestic waste oxygen uptake rates obtained are shown in Figure T5 for the

0.0l4 loading, in Figure l7 for the 0.029 loading, and for the 0.047

loading in Figure l9.

OXYGEN UTILIZATION DATA

The quanity of oxygen utilized as a function of time was calculated

for each oxygen uptake rate determination by taking the area under the

oxygen uptake rate vs. time curve. The resultant data is shown in Figures

4, 6, and 8 for the pulp and paper waste, in Figures l0, l2, and l4 for

the textile waste, and in Figures l6, l8, and 20 for the domestic waste.

These curves do not include that portion of oxygen which goes to satisfy

cellular maintenance energy requirements, often referred to as "endogenous

oxygen".

OTHER DATA

Shown in Table 4 are the loading factors, COD removal and sludge

production data for each of the experiments. The times for essentially

complete COD removal and complete oxygen utilization are shown in Table 5.

Also shown in this table are the percentage of soluable COD uptake in the

first one minute after the reactor was loaded for each of the experiments

and rate of COD removal assuming zero order. Table 6 contains data

29 Eshowing the percentage of theoretical (mass balance) oxygen utilizationobtained for each determination method. In Table 7 are shown kineticcoefficients calculated from the data collected.

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I

V DISCUSSION OF RESULTS

The data obtained in the course of these experiments may be viewed ini

a number of different contexts. The various methods used to caIcuTate the

quanity of oxygen utiTized obviousiy do not agree. The variation in the

ratio of rate of organic transfer to rate of organic stabiTization,

measured as rate of oxygen transfer, seems to indicate a proportionaiity

to initiai Ioading rate. The importance of Toading factor to a number

of parameters certainiy merits inspection. FinaTTy, the question of the

appTicabiTity of oxygen utiTization data to proposed design approaches

must be addressed.

DXYGEN UTILIZATION DETERMINATION

Stoichiometric considerations dictate that the quanity of potentiai

oxygen demand satisfied in an aerobic treatment system must be equivaient

to the quanity of oxygen utilized pTus the quanity of organic carbon

incorporated into new siudge. In these experiments, oxygen demand was

measured as COD, a parameter which does not take into account the oxygen

that potentialiy goes into oxidation of nitrogen compounds. However,

because the puip and paper and textiTe wastes were found to be nitrogen

Timited, the nitrogenous oxygen demand was ignored. This assumption

apparentTy had no signficant effect on the oxygen utiiization determin-

ation techniques used since none of these techniques yieided a utiIiz-

ation greater than that predicted from mass baTance considerations for

the puTp and paper and textiTe wastes. If a sizeabie nitrogenous oxygen

demand had exsisted in any of the wastes, measured oxygen utiiization

shouTd have exceeded the predicted quanity. In the case of the domestic

waste, which was not nitrogen Timited, the data is a bit more compiicated.

53

I

54

Nitrification did apparent1y occur during these experiments. This was g

ref1ected by certain of the oxygen uti1ization ana1yses methods but not

by others.

DIRECT MEASUREMENT METHOD. Certain1y one of the most easi1y run and

Teast subject to error test common1y emp1oyed by the sanitary engineer is

the direct measurement of oxygen uptake rate. The data co11ected by this

method in these experiments, however, yie1ded oxygen uti1ization va1ues

which varied—from 196 percent of that predicted by mass ba1ance consider

ations for 0.014 initia1 Toading of domestic waste to 17 percent for 0.029

initia1 Toading of domestic waste. GeneraT1y, the va1ues obtained for

the pu1p and paper waste were Tower than predicted theoretica11y. The

texti1e waste data was Tower in the case of two of the experiments and

higher for the third. Oxygen usage for the domestic waste ca1cu1ated by

this method apparant1y ref1ected a nitrification demand, the va1ues being

higher than predicted for two of the runs. In the case of the 0.029

initia1 Toading of domestic waste, however, the va1ues obtained were

Tower.

AVERAGED METHOD. The idea of using these directTy measured uptake

rates to ca1cu1ate a Kla that cou1d be used to, in turn, ca1cu1ate oxygen

uti1ization, yie1ded, as wou1d be expected, no better resu1ts. The ratio

between the va1ues ca1cu1ated by this method and the va1ues ca1cu1ated

by the direct measurement method was a function of which direct measure-

ment method va1ues for uptake rate were se1ected. Because se1ection 4was random, this ratio varied wide1y from 2.07:1 for the 0.029 Toading 4

of domestic waste to 0.44:1 for the 0.014 Toading of domestic waste. 4

GeneraT1y an increase in Toading factor tended to show a corresponding 4

55 i

increase in this ratio. No simple proportion, however, was found to . éexist. One interesting aspect of these two methods was the difference Ein endogenous uptake rate calculated from each. The direct measurement

method yielded values that were generally lower, although the total

quanity of oxygen utilized was usually higher for this method.

BLOK-BENEFIELD STEADY STATE METHOD. Oxygen utilization calculated

useing the Blok-Benefield method for evaluating Kla generally were the

lowest of the four methods used. Evaluation of K]a in the case of thepulp and paper waste was quite difficult since the reaeration of the mixed

liquor did not yield a linear plot of the ln (CS - Ct) versus time, as

is shown in Figure 2l. A possible, if somewhat unsatisfying, explaination

is that the high concentration of colloidal matter in this waste caused

some interference with the DO probe.

Although Blok reported very good results using his method and

comparing the oxygen utilization values with those values predicted by

a mass balance analysis of his system, these experiments yielded values

which were much too low. Blok did, however, warn against the application

of his theories to such long run experiments. In the case of the single

experiment which was of the length Blok characterized as "short term" the

oxygen utilization curve obtained coincided with the theoretical curve.

For each of these methods, the shape of the oxygen utilized versus

time curve was consisteht with the other methods. Comparison of more

than two of these methods in this regard was somewhat repititious,sinceeach

of the indirect methods was an amplification of the same curve. g

Only the direct measurement method was unique. Whatever variations in ishape may occur between the oxygen uptake rate curves obtained by the i

56

direct measurements method and those curves obtained by the other methods,

the shapes of the oxygen utilization curves were remarkably similar. The

times required to complete non-endogenous transfer of oxygen were virtually

the same for each run. This is, perhaps, an indication that the problem in

evaluating oxygen utilization in a batch reactor is associated with

evaluating K1a. If this is the case, then use of the time to end ofoxygen uptake as the time to end of stabilization as proposed by the weston

group is valid.

CONSIDERATION OF LOADING FACTOR

The difference between the ratio of time of COD transfer to time of

COD stabilization, measured as non-endogenous oxygen uptake time, was

found to vary as the initial loading factor. One possible explaination

for this is that the initial uptake of COD by the organisms was a

greater percentage of the COD stabilized at the lower loading factor.

This idea might be used to explain the contact—stabilization variation of

the activated sludge process. In the case of these wastes and loading

factors, however, such was not found to be the case. The percentage of

soluble COD removed in the first one minute of these experiments generally

increased with increasing initial loading factor, as is shown in Table 5.

If this were the case, the percentage of COD uptaken initially would be

higher at lower loading factors. The difference in transfer and stabiliz-

ation times was more likely a result of stabilization of microbial mass,

loss of mass occurring at the lower loadings and after stabilization of

biodegradable COD.

The rate of removal of COD, assumed to be zero order as proposed by

Weston, was found to be generally unrelated to the initial loading factor,

57

shown in Table 5. Nhile, substrate removal for most of the experiments

appeared to follow a higher order of removal, this order was not easily

discovered. In the case of the textile waste, the simplest of these

wastes tested, removal was zero order, following an initial uptake.

Despite this apparent removed behavior, however, oxygen utilization,

and therefore substrate stabilization was closer to first order for

all three wastes.

APPLICATION OF OXYGEN UTILIZATION DATA TO DESIGN

As has been previously discussed, the non—endogenous oxygen uptake

time can probably be taken as equal to stabilization time, as long as

solids destruction did not occur. The results of these experments cast

grave doubt upon use of oxygen uptake data for other design purposes,

however, The problem of mass balance of oxygen demand and oxygen

utilized in the system has already been discussed. The idea that sludge

production can be defined as

X =CODremovedl.42

is, nonetheless, directly based upon mass balance and an assumed

microbial chemical formulation. The argument of Blok and Benefield

that

Ka=iT°zlä7<'would imply that a change in solids concentration, X, must be accompanied

by a corresponding change in R, the endogenous oxygen uptake rate.

Although solids concentration decreased in the course of a number of the

experiments, the endogenous uptake rate always remained constant or

increased, and usually the latter. It is possible that the original

58

MLVSS concentration represented a very high proportion of non-viable

but biodegradable matter. Growth of new microbical mass in the course

of the experiment may have been insufficient to offset the loss of

non-viable solids. This could account for this phenomona.

Evaluation of design parameters for these wastes by the method

proposed by Benefield is highly dependent upon these solids data.G

without some idea of what the endogenous utilization rate actually is,

the oxygen requirement coefficients, a and b, and yield coefficient, Y,

are apparently not obtainable for these wastes. The values shown in

Table 7 assumes that final MLVSS represents all viable organisms and

the endogenous respiration rate is calculated on this basis. It is

apparent that these coefficients are not at all reasonable. The method

of obtaining kinetic coefficients proposed by Benefield is, then, not

applicable to these experiments.

1

1

VI CONCLUSIONS

Evaluation of the data from the series of batch experiments has led

to the following conclusions:

l. Currently used methods of quantifying oxygen uptake rate,

especially for batch reactors, yield values of oxygen

utilization considerably lower than those predicted by

_ mass balance considerations for these three wastes. In

the face of Blok's published data indicating much better

results with a short run reactor, it must be assumed

that the length of run selected was at least partially

responsible.

2. while quantitatively unsatisfactory, the methods for

determining oxygen uptake used in these experiments

seem to be of some use as monitors of biological

systems. Changes in slope of the oxygen utilization

curve were found to be more apparent at lower

loadings.

3. For the pulp and paper waste, oxygen transfer appearedi

to be other than first order. This may have been due

to interference with the DO prove by the colloidal

material present in the waste.

4. Apparent variations in the ratio of transfer time to

stabilization time were probably due to biomass

destruction.

C59

60

5. Percentage of soluble COD initially removed was found

to vary with initial loading factor.

6. The method proposed by Benefield for quantifying

the kinetic coefficients, Y, Kd, a, and b was notapplicable to these wastes.

Rmznencts1.Goodman, B. and Englande, A. J., "A Unified Approach to Activated

Sludge Design", Journal water Pollution Control Federation, 4B, 3312 (1974). 1

2. Lawrence, A. W., and McCarty, P. L., "Unified Basis for BiologicalTreatment Design and Operation", Journal Sanitary EngineeringDivision, ASCE, BB, 757 (1970).

3. Adams, C. E., Jr. and Eckenfelder, W. H., Jr., Process DesignTechnigues jpp_Industrial waste Treatment, Enviro Press,Nashville, Tenn., 1974.

4. Monod, J., "The Growth of Bacterial Cultures", Annual Review_gBMicrobiology, Vol. III, 1949.

5. Metcalf, and Eddy, Inc., Nastewater Engineering, McGraw-Hill,New York, New York, 1972.

6. weston, R. F., "Fundamentals of Aerobic Biological Treatmentof Nastewater", Public works, November 1963.

7. Bhatla, M. N., Stack, V. T., Jr., and weston, R. F., "Designof Nastewater Treatment Plants from Laboratory Data", Journalwater Pollution Control Preperation, BB, 601 (1966).

8. Vath, C. A., Sitman, H. D., and weston, R. F., "The Significanceof Batch Treatment Kinetics in Activated Sludge Design",Proceedings, 24th Industrial Haste Conference, PurdueUniversity, 1969.

9. Blok, J., "Respirometric Measurements on Activated Sludge",Mater Research, 8, 11 (1974).

10. Benefield, L. D., Randall, C. N., and King, P. H., "TemperatureConsiderations in the Design and Control of Completely-MixedActivated Sludge Plants", Presented at Bpg_National ConferenceQp_Enviromenta1 Bpgineering Research, Development and Design,Gainesville, Florida, July 20-23, 1975.

'_—”

ll. Pirt, S. J., "The Maintenance Energy of Bacteria in GrowingCultures , Proc. BByB Soc., BBB BB, London, 1BB, 224 (1965).

12. Herbert, D., "Some Principles of Continuous Culture", inRecent Progress lQ_Microbiology, G. Tunevall (Ed.),Blackwell Scientific Pub., Oxford, Eng., 1958. E

61

62l3. Fair, G. M., Geyer, J. C., and Okon, D. A., "Aeration and Gas

Transfer", Elements pj_Water Supply gpg_Wastewater Disposal,2nd Edition, John Wiley and Sons, New York, New York, l97l.

l4. Finn, R. K., "Agitation-Aeration in the Laboratory and inIndustry", Bacteriological Reviews, l8, 254 (l954).

l5. Eckenfelder, W. W., Jr., "Aeration and Mass Transfer",Industrial Water Pollution Control, McGraw-Hill, New York,New York, l966.

l6. Swilley, E. L., Bryant, J. D., and Busch, A. W., "Significanceof Transport Phenomena in Biological Oxidation Processes",Proceedings, l4th Industrial Waste Conference, PurdueUniversity, l964.

l7. Busch, A. W., Aerobic Biological Treatment pf_Waste Waters -Principles apg_Practice, Oligodynamics, Houston, Texas, l97l.

l8. Standard Methods jpj_tpg_Examination gf_Water gpg_Wastewater,l4th Ed., l976.

l9. Eckenfelder, W. W., Jr., and Ford, D. L., "Engineering Aspectsof Surface Aeration Design", Proceedings, 22nd Industrial WasteConference, Purdue University, l967.

I

CI

I

I

I

APPENDIXDATA

FOR 0.32 INITIAL LOAOING OF PULP AND PAPER NASTE

BLOK-BENEFIELD METHOD AVERAGED METHOD MASS BALANCE METHOD DIRECT MEASURENFNT

TIME FILTERED COD DISSOLVED OXYGEN K1a=O.157 K]a=0.487 K]a=1.58 METHODmin. REMAINING REMOVED CONC. DEFICIT UPTAKE OXYGEN UPTAKE OXYGEN UPTAKE OXYGEN UPTAKE DXVGEN

mg./1. mg./1. Ct (C —C ) RATE UT1L1ZE0 RATE UTILIZED RATI UTILIZED RATE UTILIZEOmq./1. n@./1. •./1.—min. m-./1. me./1.—min. m ./1. mr./1.—min. mr./1. m ./1.—min. mg./1.

End. 1506 0 7.45 1.10 0.17 0.0 0.54 0.0 1.74 0.0 0.15 0.0

1 1296 210 6.20 2.35 0.37 0.1 1.14 0.3 3.71 1.0 1.40 0.6

6.5 1296 210 6.05 2.50 0.39 1.3 1.22 4.0 3.95 12.5 1.45 7.6

11 1200 306 5.80 2.75 0.43 2.3 1.34 7.1 4.35 23.3 1.60 13.7

15 1160 330 3.60 4.95 0.70 4.1 2.41 12.7 7.82 40.7 1.70 19.6

20 —- —— 2.50 6.05 0.95 7.6 2.95 23.6 9.56 75.4 2.33 20.0

25 1024 482 2.25 6.30 0.99 11.6 3.07 36.0 9.95 115.5 -— —-30 736 770 2.10 6.37 1.00 15.7 3.10 40.7 10.06 156.0 1.47 45.7

40 920 578 6.75 1.00 0.28 20.4 0.00 63.3 2.04 203.9 1.40 57.0

50 960 546 6.00 1.75 0.27 21.4 0.05 66.4 2.77 214.6 1.12 67.9

60 800 626 6.07 1.68 0.26 22.4 0.02 69.5 2.65 224.3 1.23 76.9

75 912 594 6.80 1.75 0.27 23.8 0.05 73.0 2.77 230.8 1.00 09.2

90 960 546 6.80 1.75 0.27 25.3 0.85 78.5 2.77 254.3 0.93 97.

120 944 562 7.45 1.10 0.17 26.8 0.54 03.1 1.74 269.7 0.60 106.0

150 912 594 7.45 1.10 0.17 26.8 0.54 83.1 1.74 269.7 0.16 109.

DATA FOR 0.44 INITIAL LOADING OE PULP AND PAPER NASTE

BLOK-BENEFIELD METH00 AVERAGED METHOD MASS BALANCE METHOD DIRECT MEASUPIMINT

TIME FILTERED COD DISSOLVED OXYGEN METHOOmln” REMAINING REMOVED CONC. DEFICIT UPTAKE OXVGEN UPTAKE OXYGEN UPTAKE 0XYG1N UOTAnE 011910

mg./1. mg./1. Ct (CS—Ct) RATE UTILIZED RATE UTILIZED RATE UTILIZED RATE 01111210

mg./1. mg./1. mg./1.—min. mg./1. mg./1.-min. mq./1. mg./1.—m1n. mg./1. mq./1.—min. mq./1.

End. 2369 0 7.00 0.75 0.40 0.0 0.50 0.0 1.60 0.0 O.34 0.0

1 1300 1061 7.30 1.25 0.66 0.1 0.03 0.1 2.66 0.5 1.65 0.7

5 1707 662 6.14 2.41 1.28 4.8 1.60 5.9 5.14 7.4 1.65 4.6

IO 1893 476 5.80 2.67 1.42 10.4 1.77 13.1 5.69 30.3 1.40 11,7

15 1838 531 5.87 2.68 1.42 15.6 1.70 19.5 5.71 50.8 1.64 17.6

20 1734 635 5.80 2.75 1.46 20.8 1.02 26.0 5.06 71.7 1.50 23.7

25 1289 1000 5.57 2.98 1.58 26.4 1.90 33.0 6.35 94.3 1.00 01.

30 1481 088 5.72 2.83 1.50 32.0 1.00 40.1 6.03 117.2 1.33 31.2

40 1810 559 5.68 2.87 1.52 43.2 1.90 54.0 6.12 162.0 1.32 45.0

50 1426 943 4.75 3.80 2.01 56.8 2.52 71.0 0.10 217.1 2.10 59.2

60 1564 805 6.65 1.90 1.01 67.9 1.26 04.9 4.05 261.8 1.53 71.6

75 1619 750 6.72 1.83 0.97 76,0 1.21 96.0 3.90 297.4 1.20 06.2

90 1124 1245 6.60 1.95 1.03 85.8 1.29 107.3 4.16 333.7 1.10 99.5

105 905 1464 6.72 1.83 0.97 94.8 1.21 110.5 3.90 370.0 1.02 109.2

120 1100 1189 6.03 1.72 0.91 102.8 1.14 120.7 3.67 402.6 1.20 119.6

150 2195 174 7.07 1.48 0.78 115.5 0.98 144.4 3.15 456.5 1.10 142.0 1100 1139 1230 7.34 1.21 0.64 124.0 0.00 155.1 2.58 493.8 1.09 162.3

210 1200 1009 7.50 1.05 0.56 130.0 0.70 162.6 2.24 517.4 0.65 1/4.0

240 1227 1142 7.72 0.03 0.44 133.0. 0.55 166.4 1.77 520.6 0.50 176.3

270 1333 1036 7.70 0.77 0.41 133.7 0.51 167.3 1.64 530.7 0.501/6.3300

1200 1169 7.70 0.77 0.41 133.7 0.51 167.3 1.64 530.7 0.50 176.31

1 63E

64

DATA FOR 1.79 INITIAL LDADING OF PULP AND PAPER NASTE

BLOK—BENEFIELD METHOD AVERAGED METHOD MASS BALANCE METH00 DIRECT MEASDREMINTFILTERED COD DISSOLVED OXYGEN K]a=0.105 K]a=0.614 K]a=1.03 MET60DREMAINING REMOVED CONC. DEFICIT UPTAKE OXYGEN UPTAKE OXYGEN UPTAKE OXYGEN UPTAKE OXYGENmg./1. mg./1. Ct (CS—Ct) RATE UTILIZED RATE UTILIZED RATE UTILIZED RATE UTILIZED

m ./1. mn./1. m•./1.—min. m-./1. mg./1.—min. mg./1. mg./1.—min. mg./1. mg./1.-01n. wg./1.End. 2370 0 7.95 0.60 0.06 0.0 0.37 0.0 0.62 0.0 0.19 0.0

1 1855 515 7.20 1.35 0.14 0.0 0.83 0.2 1.39 0.4 0.94 0.45 1960 410 7.10 1.45 0.15 0.4 0.89 2.2 1.49 3.7 1.45 I 4.4

10 1774 596 7.10 1.45 0.15 0.8 0.89 4.8 1.49 8.0 1.10 9.815 —- =— 7.20 1.35 0.14 1.2 0.83 7.3 1.39 12.1 1.10 14.120 1102 1268 7.30 1.25 0.13 1.6 0.77 9.4 1.29 15.7 0.95 lw.125 1586 784 7.25 1.30 0.14 2.0 0.80 11.4 1.34 19.2 1.10 22.930 1492 _878 7.20 1.35 0.14 2.3 0.83 13.6 1.19 22.9 1.07 27.r40 1465 905 6.80 1.75 0.18 3.3 1.07 19.5 1.80 32.7 1.10 36.5

50 1479 891 6.80 1.75 0.18 4.5 1.07 26.6 1.80 44.5 0.95 41.5

60 1465 905 6.80 1.75 0.18 5.8 1.07 33.6 1.80 56.3 0.93 51.675 1344 1026 6.60 1.95 0.20 7.7 1.20 45.1 2.01 75.5 1.20 63.990 1183 1187 6.45 2.10 0.22 10.0 1.29 58.2 2.16 97.5 1.25 78.4

105 1183 1187 5.95 2.60 0.27 12.7 1.60 74.3 2.68 124.5 1.30 91 5120 1102 1268 6.20 2.35 0.25 15,7 1.44 91.6 2.42 153.3 1.10 107.2150 1187 1183 6.10 2.45 0.26 21.3 1.50 124.7 2.52 208.5 1.20 112.7180 1102 1268 6.60 1.95 0.21 26.4 1.20 154.2 2.01 257.6 0.87 154.0210 927 1443 7.10 1.45 0.15 29.8 0.89 174.5 1.49 290.9 0.68 166.8240 828 1542 7.45 1.10 0.12 32.0 0.66 186.8 1.13 311.0 0.75 177.4300 645 1725 7.10 1.45 0.15 36.4 0.89 213.1 1.49 350.6 0.98 205.8360 699 1671 7.00 1.55 0.16 42.1 0.95 246.2 1.60 404.3 0.72 ZT .3420 645 1725 7.40 1.15 0.12 46.8 0.71 273.0 1.18 448.1 0.60 217.6480 607 1763 7.90 0.65 0.07 48.7 0.40 284.7 0.67 463.4 0.59 219.4

DATA FOR 0.25 INITIAL LOADING OF TE)0ILE NASTE_I

BLOK—BENEFIELD METHOD AVERAGED METHOD MASS BALANCE METN00 DIRECT MEASURENENT

TIME FILTERED COD DISSOLVED OXYGEN K]a=0.850 K,a=0.92O K]a=1.470 METHODmin’ REMAINING REMOVED CONC. DEFICIT UPTAKE OXYGEN UPTAKE OXYGEN UPTAKE OXYGEN I UPTAKE 071650

mq /l~ mg Ct (CS-Ct) RATE UTILIZED RATE UTILIZED RATE UTILIZED RATE UTIIIZEDmq./1. mg./1. mg./1.-min. mg./1. mg./1.-min. mg./1. mq./1.—min. mq./1. mg./1.-min. mn./1.

End. 787 0 7.30 1.25 1.06 0.0 1.15 0.0 1.84 0.0 0.25 0.01 690 97 -— —— —— -- -— —— ·· ·· 2**9 I·I5 675 112 4.90 3.65 3.10 5.1 3.36 5.5 5.36 8.8 5.10 15.1

10 646 141 3.90 4.65 3.95 17.4 4.28 18.8 6.83 30.1 9.00 43.8

15 646 141 3.75 4.80 4.08 32.2 4.41 34.8 7.05 55.6 9.60 94.0

20 623 164 3.65 4.90 4.17 47.5 4.51 51.4 7.20 82.0 9.40 140.2

25 574 213 3.54 5.01 4.26 63.3 4.61 68.5 7.36 109.2 9.20 185.4

30 597 190 3.50 5.05 4.29 79.4 4.64 85.9 7.42 137.0 9.00 223.6

40 556 231 3.47 5.08 4.32 111.8 4.67 121.0 7.46 193.0 7.60 310.0

50 504 283 3.50 5.05 4.29 144.3 4.64 156.1 7.42 249.0 5.70 371./

60 302 485 3.70 4.85 4.12 175.7 4.46 190.1 7.12 303.3 4.80 421.4

75 258 529 6.12 2.43 2.06 206.2 2.23 223.1 3.57 355.8 4.30 487.2

90 183 604 6.45 2.10 1.79 219.5 1.93 237.5 3.08 378.1 1.50 526.1

105 138 649 6.73 1.82 1.55 228.3 1.67 247.0 2.6/ 393.6 0.80 510./

120 123 664 7.07 1.48 1.26 233.5. 1.36 252.6 2.17 402.3 0.45 541.4

135 116 671 7.15 1.40 1.19 236.0 1.29 255.3 2.06 406.5 0.50 545.6

165 131 656 7.27 1.28 1.09 238.4 1.18 257.9 1.88 410.4 0.45 549.6

195 123 664 7.30 1.25 1.06 238.8 1.15 258.4 1.84 411.0 0.38 551.3

240 138 649 7.30 1.25 1.06 238.8 1.15 258.4 1.84 411.0 0.37 551.5

270 —- -- 7.30 1.25 1.06 238.8 1.15 258.4 1.84 411.0 0.39 551.5

300 101 686 7.30 1.25 1.06 238.8 1.15 258.4 1.84 411.0 0.37 551.5

I

I

65

DATA FOR 0.49 INITIAL LOADING 0F TEXTILE 11/\5TE

BLOK-BENEFIELD METH00 AVERAGED METHOD MASS BALANCE METHOD DIRECT MEA5I‘RE1·1E1«1'TIME FILTERED COD DISSOLVED OXYGEN 1<]a=0.330 1<]a=0.360 K1a=0.520 METH00min' REMAINING REMOVED CONC. DEFICIT UPTAKE OXYGEN UPTAKE OXYGEN UPTAKE OXYGEN UPTAKE OXYGENCt (CS-Ct) RATE UTILIZED RATE UTILIZED RATE UTILIZED RATE UTILIZED

mg./1. mg./1. mg./1.-min. mg./1. mg./1.-min. mg./1. mg./1.—m1n. mg./1. mg./1.—min. mq./1.

End. 1977 0 7.00 1.55 0.51 0.0 0.56 0.0 0.81 0.0 0.20 0.01 392 185 6.90 1.65 0.54 0.0 0.59 0.0 0.86 0.0 1.65 0.75 922 155 6.07 2.48 0.82 0.7 0.90 0.8 1.29 1.1 1.80 6.8

10 937 140 5.65 2.90 0.96 2.6 1.05 2.8 1.51 4.0 2.06 15.515 .328 249 2.28 6.27 2.07 7.6 2.26 8.3 3.27 11.9 2.00 24.620 814 263 0.10 8.45 2.79 17.2 3.05 18.8 4.40 27.1 1.92 33.425 776 301 0.00 8.55 2.82 28.7 3.08 31.3 4.46 45.2 1.110 41.630 761 316 0.00 1.65 49.240 716 361 0.00 1.65 63.650 634

·443 0.00 1.60 77.7

60 582 495 0.00 1.60 91.575 —— -- 0.00 1.95 114.790 500 577 0.00 1.92 140.3

105 463 614 0.00 1.93 165.7120 340 737 0.00 1.68 169.1150 231 846 0.00 1.60 231.0155 --’ -- 0.00 8.55 2.82 317.4 3.08 346.,6 4.46 519.7 —— ——180 157 920 3.30 5.25 1.73 361.6 1.89 394.8 2.74 589.4 0.65 257.1240 149 928 5.28 l 3.27 1.08 415.3 1.18 453.5 1.70 674.0 0.40 272.4288 -- —— 5.40 3.15 1.04 441.7 1.14 482.3 1.64 715.3 —- ——289 -- -— 6.45 2.10 0.69 442.0 0.75 482.6 1.09 715.8 ~— ——300 97 980 6.57 1.98 0.65 443.8 0.71 484.6 1.03 718.6 0.41 279.0360 104 973 6.90 1.65 0.54 448.9 0.59 490.1 0.86 726.7 0.47 286.2485 93 984 7.00 1.55 0.51 450.8 0.56 492.2 0.81 729.8 0.37 294.9

DATA FOR 0.61 INITIAL LOADING OF TEXTILE NASTE

BLOK-BENEFIELO METHOD AVERAGE0 METHOD MASS RALANCE METHOD DIRECT ME/1SUR1.ME1;T

TWK FILTERED COD DISSOLVED OXYGE11 K]a=0.53O 1·<]a=0.486 1<]a=1.020 MET1100mn' REMAINING REMOVED CONC. OEFICIT UPTAKE OXYGEN UPTAKE OXYGEN UPTAKE OXYGEN UPTAEE 01Ct (CS-Ct) RATE UTILIZED RATE UTILIZED RATE UTILIZED RATE UTILIZED

mq./1. mq./1. mg./1.-min. mg./1. mg./1.-min. mg./1. mg./1.~m1n. mq./1. mg./1.—min. mg./1.

End. 1077 0 8.15 0.40 0.21 0.0 0.20 0.0 0.41 0.0 0.25 0.01 748 329 7.10 1.45 0.70 0.3 0.70 0.2 1.47 0.5 0.93 0.35 701 376 6.45 2.10 1.11 3.2 1.02 2.9 2.14 6.1 1.25 3.7

10 712 365 5.77 2.78 1.47 8.6 1.35 7.9 2.83 16.5 1.27 11.815 672 405 5.38 3.17 1.68 15.4 1.54 14.1 3.22 29.5 1.27 13.820 672 405 5.10 3.45 1.83 23.0 1.68 21.1 3.51 44.2 1.53 19.625 661 416 4.88 3.67 1.95 31.4 1.78 28.8 3.73 60.2 1.60 26.130 555 522 4.75 3.80 2.01 40.1 1.84 36.8 3.86 77.0 1.53 32.610 577 500 4.50 4.05 2.15 58.7 1.97 53.8 4.12 112.6 1.40 44.750 569 508 4.37 4.18 2.22 78.2 2.03 71.7 4.25 150.1 1.47 56460 547 530 4.23 4.32 2.29 98.4 2.10 90.2 4.39 188.9 1.40 68.175 489 588 4.05 4.50 2.38 129.9 2.19 119.1 4.58 249.3 1.27 84.110 467 610 3.92 4.63 2.45 162.7 2.25 149.1 4.71 .312.1 1.27 99.0

1115 420 657 3.87 4.68 2.48 196.0 2.27 179.7 4.76 376.1 1.27 113.91.0 3110 697 3.811 4.67 2.48 229.5

U2.27 210.3 4.75 440.3 1.40 129.7

150 2I15 792 5.37 3.18 1.69 284.2 1.54 260.5 3.23 545.3 1.60 166.2T10 1671 909 7.31 1.24 0.66 311.4 0.60 2115.4 1.26 597.4 1.00 196.1.10 201 876 7.44 1.11 0.59 321.7 0.54 294,9 1.13 617.3 0.47 209.22710 161 916 7.58 0.97 0.51 329.7 0.47 302.2 0.99 632.6 0.49 214.2270 -- -- 7.82 7.73 0.39 334.4 0.35 306.5 0.74 641.6 0.50 219.3310 139 938 7.95 0.60 0.32 337.1 0.29 308.9 0.61 646.7 0.43 226.3190 139 938 7.95 0.60 0.32 337.1 0.29 308.9 0.61 646.7 0.38 229.8450 139 938 7.95 0.60 0.32 337.1 0.29 308.9 0.61 646.7 0.38 230.4

1

111T

66

0ATA FOQ 0.014 INITIAL L000IN6 01 00%[S116 HAS11

BLOK—BENEF1ELD METHOD AVYRAGLU M1TH00 MASS BALANC[ METHOD DIRECT MKASVQIMFNTTIML FILTERED C00 DISSOLVEU OXYGEN MLTH00min' REMAINING REMOVED CONC. DEFICIT UPTAKE OXVGEN UPTAKE OXYGEN UPTAKE OXYGEN UVTARE 0XYOiN V

mg /1. mg /1. Ct RATE UTILIZEU RATE UTIL17E0 RAT{ UTILIZED RATE UT1l17{Umg./1. mq./1. mg./1.-min. mg./1. mg./1.—m1n. mg./1. mq./1,—min. mq./1. mq./1.-min. mq./1

[nd. 91 0 7.40 1.15 0.37 0.0 0.40 0.0 0.36 0.0 0.24 0.01 80 11 6.60 1.95 0.62 0.1 0.68 0.1 0.62 0.1 0.95 0.45 82 9 6.00 2.55 0.82 1.5 0.89 1.6 0.81 1.6 0,00 2.9

10 61 30 6.05 2.50 0.80 3.7 0.87 4.0 0.79 3.7 0.92 6.015 77 14 6.10 2.45 0.78 · 5.8 0.85 6.3 0.78 5.8 1.00 9.620 77 14 6.17 2.38 0.76 7.8 0.83 8.5 0.75 7.8 1.00 14.425 42 49 6.23 2.32 0.74 9.7 0.81 10.5 0.74 9.6 1.00 17.230 97 —— 6.29 2.26 0.72 11.4 0.79 12.4 0.72 11.4 0.93 20.040 50 33 6.64 1.91 0.61 14.2 0.66 15.4 0.61 14.2 0.73 26.750 76 15 7,20 1.27 0.41 15.4 0.44 16.7 0.40 15.3 0.20 F0.460 —— —· 7.30 1.25 0.40 15.5 0.43 16.0 0.40 15.4 0.20 20.975 57 34 7.30 1.25 0.40 15.5 0.43 16.9 0.40 15.4 0,24 10.200 —— -— 7.30 1.25 0.40 15.5 0.43 16.9 0.40 15.4 0.24 10.J

0414 F00 0.029 INITIAL LOA01NG 0F 00MFST1C NASTE

BLOK—BENEV1EL0 METHOD AVERAGEU MFTH00 MASS RALANCE MFTHOD UIPECT Mf4"“1VEKTTIME FILTERED COD 01SSOLVE0 OXYGEN N[TM10m‘n'

REMAINING REMOVFD CONC. DKFICIT UPTAKE OXYGKN UPTAKE 0XYO[N UVTAKL 0¥Y0[N UVTAKF 0*1010mq /‘· mg Ct (CS—Ct) RATE UTILIZED RATE UT1LI7[0 RATE UT1lI7[D 041F 01111711

mq./1. mg./1. mg./1.-min. mg./1. mg./1.-min. mq./1. mq./1.—min. mq./1. mg./1.—min. 11111./1.{nd. 125 0 8.45 0.10 0.01 0.0 0.08 0.0 0.23 0.0 0.19 0 0

1 86 39 7.10 1.45 0.21 0.1 1.18 0.6 3.31 1.5 1.04 0.45 103 22 5.92 2.63 0.39 0.8 2.15 4.6 6.01 12.6 1.03 2.5

10 93 32 5.31 3.24 0.48 2.6 2.64 14.4 7.40 54.7 1.00 7.915 78 47 5.72 2.83 0.42 5.8 2.31 32.1 6.46 88.2 —·-- -—-20 65 60 5.96 2.59 0.38 7.7 2.11 43.0 5.91 110,0 0.90 15.525 61 64 6.20 2.35 0.35 9.5 1.92 52.8 5.37 145.0 0.87 10.030 64 61 6.65 1.90 0.28 11.0 1.55 61.3 4.34 168.2 1.07 22.940 46 79 6,95 1.60 0.24 13.5 1.31 74.9 3.65 205.0 0.80 10.350 44 81 7.04 1.51 0.22 15.7 1.23 87.1 3.45 230.0 0.00 1~.460 40 85 7.15 1.40 0.21 17.7 1.14 00.3 3,20 270.0 0.00 4U.%75 52 73 7.31 1.24 0.18 20.1 1.01 111.6 2.03 311.7 0.¤0 51 790 46 70 7.40 1.07 0.16 23.0 0.87 127.5 2.44 347 0 0.60 50.0

105 42 83 8.14 0.41 0.06 23.8 0.33 132.1 0.94 360.7 0.23 63.0120 45 00 0.45 0.10 0.01 24.0 0.08 133.0 0.23 375,0 0.20 ·4,H

0414 F09 0.047 INITIAL LOADING 0F 00MESTIC NASTE

0LOK—B[N[F1[LD METH00 AV10AOE0 M[1000 MAS5 HALAHCK M11H00 01Pf¤’FILTEREU COD D15SOLVED OXYGFN K]a:0.452 KTa=0.102 K]a:0.336 M1T~0Fmin' RENAINING REMOVED CÜNC. DEFICIT UPTAKE OXVGFN UPT^K[ OXYGEN UPTßK[ 0XYOLN UV14•1 011010

mg mg /1. Ct (CS-Ct) RATK UTILIZED RAT? UTILIZED 0A1[ UT1L17[0 9ATE 0'1L1T10mq./1. mq./1. mg./1.—min. mg./1. mg./1.-min. mg./1. mg./1.—min. mg./1. mg /1 —min. ww./1,

{nd. 139 0 7.33 1.22 0.55 0.0 0.23 0.0 0.41 0.0 0.10 0.01 62 77 6.48 2.07 0.94 0.2 0.40 0.1 0.70 0.1 0,40 0,5 49 90 6.70 1.85 0.84 1.6 0.35 0.7 0.62 1,2 0.40 1.4

10 94 45 6.70 1.85 0.84 3.0 0.35 1.3 0.62 2.2 0.50 3.15 66 73 6.67 1.88 0.85 4.5 0.36 1.9 0.63 3.3 0.60 5,420 53 06 6.62 1.93 0.07 6.0 0.37 2.5 0.65 4.5 0,40 7,525 78 61 6.59 1.96 0.89 7.6 0.38 3.2 0.66 5.6 0.45 0.330 127 12 6.55 2.00 0.00 9.2 0.38 3.0 0.67 6.0 0,40 11.140 156 —~ 6.40 2.07 0.04 12.0 0.40 5,4 0.70 0.5 0.40 14.450 40 90 6.41 2.14 0.*)/ 16.65 0.41 7.0 0.// 12.1 0,46 17.1160 57 02 6.30 2.17 0.90 20.6 0.42 0,7 0.71 15.1 0.17 20.675 69 70 6.54 2.01 0.01 26.0 0.39 11.0 0.60 10.3 0.35 74.U90 57 02 6.60 1.95 0.88 30,6 0.37 13.0 0.66 22.7 0.35 27.6

105 41 98 6.64 1.91 0.86 34.7 0.37 14.7 0.64 25.8 0.33 10.1120 62 77 6.70 1.85 0.84 38.4 0.35 16.3 0.62 28.5 0.31 13J150 -— —— 6.75 1.80 0.81 44.7 0.35 19,0 0.60 33.2 0.30 38.7100 29 110 6.70 1.85 0.84 50.2 0.35 21.3 0.62 37.3 0.35 44.1210 37 102 6.97 1.58 0.71 53.8 0.30 22.8 0.53 40.0 0.28 40.0300 21 118 7.00 1.55 0.70 56.5 0.30 24.0 0.52 42.0 0.18 54.3

1111

1 1

A COMPARISON OF A~

OXYGEN UTILIZATION DETERMINATION TECHNIQUES

FOR THE ACTIVATED SLUDGE PROCESSby

warren Michael Stallard

(Abstract)Batch reactor experiments were conducted on three different waste-

waters and the data obtained used to evaluate and compare oxygen utiliz-

ation determination techniques. Also evaluated was a method for use of

oxygen utilization data to determine certain kinetic coefficientsT required for design of activated sludge treatment systems.

Little agreement between the various oxygen utilization determination

techniques was found, casting doubt upon all of the techniques. Con-

sideration of the mass balance of the reactor contents yielded no agree-

ment, either. The coefficient evaluation technique was not found to be

applicable.

A description of the investigation and the various factors considered

is included.

A