United States
Environmental Protection
Agency
Municipal Environmental Research EPA-600/2-78-061
Laboratory June 1978
Cincinnati OH 45268
Research and Development
xvEPA
Nitrification of
Secondary Municipal
Waste Effluents by
Rotating Bio-Discs
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1 Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7 Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point-and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161
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EPA-600/2-78-061
June 1978
NITRIFICATION OF SECONDARY MUNICIPAL
WASTE EFFLUENTS BY ROTATING BIO-DISCS
Jack A. Borchardt
Shin Job Kang
Tai Hak Chung
The University of Michigan
Ann Arbor, Michigan M3109
Grant No.
Project Officer
Edward J. Opatken
Wastewater Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio ^5268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO ^5268
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DISCLAIMER
This report has been reviewed by the Municipal Environmental
Research Laboratory, U.S. Environmental Protection Agency, and ap-
proved for publication. Approval does not signify that the contents
necessarily reflect the views and policies of the U.S. Environmental
Protection Agency, nor does mention of trade names or commercial
products constitute endorsement or recommendation for use.
XI
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FOREWORD
The Environmental Protection Agency was created because of increasing
public and government concern about the dangers of pollution to the health
and welfare of the American people. Noxious air, foul water, and spoiled
land are tragic testimony to the deterioration of our natural environment.
The complexity of that environment and the interplay between its components
require a concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem solu-
tion and it involves defining the problem, measuring its impact, and
searching for solutions. The Municipal Environmental Research Laboratory
develops new and improved technology and systems for the prevention, treat-
ment, and management of wastewater and solid and hazardous waste pollutant
discharges from municipal and community sources, for the preservation and
treatment of public drinking water supplies, and to minimize the adverse
economic, social, health, and aesthetic effects of pollution. This publica-
tion is one of the products of that research; a most vital communications
link between the researcher and the user community.
This study was concerned with the applicability of rotating biological
surfaces for achieving nitrification of secondary treated effluents. The
report covers the effect various parameters have on the performance of the
rotating biological surfaces and their capability to respond to stress
conditions.
Francis T. Mayo
Director, Municipal Environmental
Research Laboratory
111
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PREFACE
The emergence of public cognizance of eutrophication as a problem has
come about slowly over the past 15 years. The outcry relative to the so-
called "death of Lake Erie" was but one evidence of concern. Nutrients in
sewage effluents are partly responsible for the fertility of receiving
waters, and the two macro-nutrients which play a large part in this response
are nitrogen and phosphorus. Nitrogen thus ranks high as a problem constit-
uent in waste treatment effluents. As a result, the limitation of this
element in treated effluents is frequently being required.
Both high-rate trickling filters and lagoons often pass substantial
quantities of ammonia-nitrogen to their receiving waters. Frequently, the
original choice of these types of processes was based on their inherent sim-
plicity. Any type of nutrient removal process added to these systems which
is essentially complex would destroy the desired level of simplicity in their
overall operation.
One possibility which would certainly meet the criteria for simplicity
would be the rotating biological surface (RBS). This device used solely by
itself could nitrify the plant effluent, or in instances where subsequent
denitrification is practiced would contribute to removal of nitrogen from
the effluent. The pertinent questions are: will the RBS induce sufficient
nitrification, is it dependable, and what loading factors are possible?
A study of RBS nitrification had to be carried out in the field so as to
utilize the actual waste effluents from the processes in question. These ef-
fluents contained natural bacterial seed and reflected the typical fluctua-
tions in concentration and flow normally experienced at treatment facilities.
The research as envisioned involved the basic biology of nitrification
as induced by the RBS system. Nitrification used in this regard is a bio-
oxidation reaction requiring the culturing and attachment of the essential
species of autotrophs on the contact surfaces. The organisms are known to
be sensitive, and difficult to culture, and their growth response mechanisms
are not well understood. While the application of RBS to the overall prob-
lem of nitrification in two select types of waste treatment is the major
issue of this research, a side issue of some import must be the furthering
of the knowledge of nitrifier metabolism.
IV
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ABSTRACT
This" research program involved the study of biological nitrification of
two different municipal waste plant effluents; one a high-rate trickling fil-
ter effluent, and the other a flow-through, two-stage, raw sewage lagoon
effluent.
The effluents from each of these plants contained nitrogen compounds in
the form of organic nitrogen, ammonia and more 'oxidized forms, up to and in-
cluding nitrate. It was the objective of this research to design and build
two rotating bio-disc pilot plants which were added to the effluent end of
the aforementioned municipal waste plants. Operation of these pilot '-units
was monitored to determine whether rotating bio-disc surfaces (RBS) could
provide a satisfactory level of nitrification in either one or both of these
waste plant effluents.
In the case of the high-rate trickling filter, the results were positive
and the report considers the factors of pH, alkalinity, loading, and staging
from the point of view of design of RBS systems to induce optimum nitrifica-
tion.
The study at the raw sewage lagoon was exceedingly difficult to deal
with. For most of the year, no ammonia-nitrogen was present in the effluent
because of algae stripping. Also during the bitter cold winter, freeze-ups
were common. As a result, the lagoon aspect of this project was cancelled.
This report was submitted in fulfillment of Grant No. RSOjUO? by the
University of Michigan, Department of Civil Engineering, under the partial
sponsorship of the U.S. Environmental Protection Agency. This report covers
the period from January 6, 1975 "to March 31, 1977- The work was completed
August 51, 1977-
v
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CONTENTS
Foreword ................................ iii
Preface ........ . ....................... iv
Abstract ................................. v
Figures ................................ viii
Tables ................................. • ix
Abbreviations and Symbols ........................ x
Acknowledgments ............................
1. Introduction .......................... 1
General .......................... 1
Nitrification ....................... 1
Description of bio-disc process .............. 5
Historical development of RBS ............... 7
Biological nitrification using RBS ............. 8
2. Conclusions ........................... 10
J. Recommendations ......................... 12
Field work ......................... 12
Laboratory work ...................... 12
h. Experimental Procedures ..................... 13
Saline waste treatment system ............... 13
Genoa waste treatment system ................ 18
Pilot plant design ..................... 20
Sampling .......................... 22
Construction ........................ 23
VII
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CONTENTS (Concluded)
5- Experimental Observations 2^
General 2^
Experimental design 25
Flow loading as affecting nitrification 29
Ammonia loading as affecting nitrification ......... 3^-
Staging 35
Nitrification as affected by pH and alkalinity 39
Effect of temperature on nitrification ^3
Speed of rotation, oxygen effects, and slime buildup .... 51
Shock loads 65
Flow reversal 77
Simplified kinetics applied to RBS nitrification 80
Material balance relationships . 83
References 90
Appendices
A. Nitrogen Data—Saline 96
B. Suspended Solids and COD Data Sheets —Saline 120
C. Data Sheets — Genoa 130
D. Pilot Plant Layout 133
Vlll
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FIGURES
Number Page
1 Nitrogen cycle 2
2 Nitrosomonas k
3 City of Saline Wastewater Treatment Plant lU
h Summary of nitrification performance versus hydraulic loading
rates at Saline, Michigan . 16
5 Summary of temperature values versus hydraulic loading rates
at Saline 1?
6 Genoa wastewater treatment 19
7 Effects of hydraulic loading rate on nitrification at Saline. . 32
8 Ammonia removal normalized with regard to influent concentra-
tions. 33
9 Mass loading and removal at Saline 36
10 Stage loading versus ffiL-N removal efficiency 38
11 Effect of alkalinity on nitrification hh
12 NHxj-N oxidation as a function of alkalinity 45
13 NBj-N oxidation as a function, of pH U6
~Lk Laboratory temperature study hQ
15 Normalized temperature data. 4 9
16 Temperature factor based on norm of 20 C. . 50
17 Temperature effects on nitrification rate. .... 52
18 Effects of rotating speed on nitrification (2-ft discs) 5^
19 Oxygen uptake of disc scrapings 55
20 Rotating speed versus nitrification at Saline 57
21 Rotating speed versus effluent NHj-W and D.O. at Saline 58
22 Rotating speed versus D.O by stages at Saline 59
23 Typical biomass measurements 62
2k Flow shock effects 67
25 Strength shock effects 69
26 Profiles of h-hr shock load at Saline 78
27 Comparison of predicted and observed ammonia profiles at steady
state 86
28 Correlation of observed and predicted ammonia profiles at steady
state 88
IX
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TABLES
Number Page
1 Inorganic Nitrogen Fractions in Saline Pilot Plant Influent. . . 15
2 Design Data - Genoa, Ohio 20
3 Outline of Runs Performed at Saline 26
k Surface Distribution and Flow Loading to Stages 27
5 Data Locations (3 gpd/ft loading) 27
6 Design of Overall Experiment 28
7 Flow Versus Time and Nitrogen Oxidized in Stage 1 3k
8 Effect of Staging on HHj-N Renwpval for Constant Flow (3 gpd/ft2
loading) 37
9 Final Experimental Results kO
10 Reported Optimal pH Values for Nitrification kl
11 Typical pH and Alkalinity Values During Nitrification at Saline. k2
12 Biomass and Oxygen Uptake 56
13 BODc of Saline Pilot Plant Samples (mg/,0) 60
1^ Scrape and Weigh Study of Saline Biomass 63
15 Flow Shock Evaluation 68
l6 Concentration Shock Evaluation 68
17 Flow Shock Data 70
18 Concentration Shock Data 70
19 Distribution of Biomass and Shock Removal 72
20 Further Analysis of Table Ik 76
21 Response of Pilot Plant Unit to Initiation of Flow Reversal. . . 8l
22 Calculated Kinetic Coefficients from Saline Pilot Plant 85
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ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS
Alk. -- alkalinity—the sum of the bicarbonate, carbonate, and hydroxide
ions expressed as CaCO^, mg/2
BOD,- -- 5-day, 20°C, biochemical oxygen demand, mg/,0
D.O. -- dissolved oxygen, mg/,g
gpd -- gallons per day, usually expressed on a per square foot b.asis
RBS -- rotating biological surface
rpm -- revolutions per minute
SS — suspended solids
temp. — temperature in degrees Celsius
SYMBOLS
A -- surface area, m
A -- surface area, m /first stage (where subscript denotes stage)
A. -- ammonia-nitrogen concentration at ith stage, mg/&
B. — nitrite-nitrogen concentration, mg/,0
C -- bulk fluid substrate concentration mg/£
C. -- nitrate-nitrogen concentration at ith stage, mg/£
C — initial substrate concentration, mg/J
o
g -- grams
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ABBREVIATIONS AND SYMBOLS (Concluded)
K -- half-saturation coefficient, mg/,g
s
K -- half-saturation coefficient for Nitrobacter, mg/i
sb
K -- half-saturation coefficient for Nitrosomonas, mg/,0
ss • '
K -- rate coefficient for ammonia oxidation, mg/^/hr
Kp — rate coefficient for nitrite oxidation, mg/^/hr
mg -- milligrams
N -- nitrogen gas
NO -- nitrite-nitrogen, expressed as N, mg/^
NO -- nitrate-nitrogen, expressed as N, mg/,0
N -- sum of nitrite plus nitrate, expressed as N, mg/,0
OX
NH -- ammonia-nitrogen, expressed as N, mg/^
pH -- log (base 10) reciprocal of hydrogen ion concentration, g/£
Q -- flow rate, £/hr
R — steady state removal—biological removal of substrate under
ss
relatively constant flow and load
R , -- shock load removal—that additional removal above the R value
si ss
when a shock load is imposed
V -- volume of a stage, a
X -- biomass, mg/m
Y -- yield coefficient, mg cells/mg substrate
jj -- specific growth rate, 1/hr
u -- maximum specific growth rate, 1/hr
max
Xll
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ACKNOWLEDGMENTS
This research project has received full cooperation of all
city officials at both Saline, Michigan, and Genoa, Ohio. Waste
treatment plant personnel provided not only the site for pilot
plant operations but also power connections and full access to
all facilties. Sincere thanks are extended to Wayne Smith, Board
of Public Affairs, Genoa, Ohio, and to Elwin A. Strait, Superin-
tendent, City of Saline, Michigan.
Xlll
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SECTION 1
INTRODUCTION
GENERAL
This report summarizes the work done over a 2-1/2-year period in the
study of biological nitrification and the use of rotating discs to enhance
this natural bio-oxidation process. The work has utilized the effluent from
a municipal high-rate trickling filter as the basic substrate for the nitri-
fiers. Many of the observations have been checked or verified in the labora-
tory where a synthetic substrate has been used.
Additional work using a municipal flow-through-type lagoon system was
attempted. Insufficient ammonia nitrogen was present for sustained opera-
tion, and inclement weather made continuous operation exceedingly difficult
to maintain. As a result, this portion of the work was curtailed.
When this research was first contemplated there were many facets of bio-
disc nitrification which were quite obscure. Many of these problems have
been cleared up only to generate new questions. However, there is little
doubt that progress in the understanding of biological nitrification is much
more advanced than was true when the work was initiated.
NITRIFICATION
Nitrification can probably best be defined by reference to the usual
nitrogen cycle depicted in most beginning courses in science or biology.
Figure 1 indicates such a cycle in which plant life is the general source of
sustenance for animal life. Organic matter subsequently passes on by death
of the cellular matter or the production of waste products to become the
raw ingredients for the first stage of the cycle, namely, that of ammonifi-
cation. Many organisms hydrolyze complex organic matter to produce the
breakdown of protein through peptones, peptides, and eventually release of
ammonia. The ammonia is generally oxidized by a relatively exclusive and
restrictive group of organisms which are strict autotrophs. Their entire
energy resources comes from the oxidation of ammonia to nitrites and '-
trites to nitrates. The first step is carried on by species of Nit.'".' ^omonas
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PLANT
LIFE
SYMBIOTIC
NITROGEN ^FJXATION
(RHYZOB^AJ
DEN1TRIF1CAT!
R OXYGEN
("USES ENERGY
CLOSTR1DIA)
Figure 1. Nitrogen cycle.
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and Nitrosococcus and the second step by Nitrobacter. Recent evidence in
the literature indicates that certain fungal forms can also carry on this
process. These are apparently heterotrophs and of less importance in nature
than the true bacterial forms. Nitrates, of course,, are a major fertilizing
element for much farm and garden produce. With the return of the nitrogen
in the form of nitrate to the plant, the cycle starts over again.
Nitrification may now be defined from Figure 1 as that step in the ni-
trogen cycle which converts the ammonia to the more oxidized forms of ni-
trite and nitrate. It is only by going through this step that the fertility
of the nitrogen compounds may be destroyed by the succeeding step of deni-
trification. There is no simple, straightforward mechanism for converting
ammonia directly into free nitrogen gas in nature. Similarly, the reduction
of nitrite and nitrate back to ammonia would merely recycle the nitrogen
without reducing it in quantity.
The nitrogen cycle has other ramifications, of course. Nitrogen from
the atmosphere can be fixed in the soil, and normally is, by many symbiotic
forms of organisms living in and on the root systems of legumes. To a
lesser extent, free nitrogen is also fixed in the living cells of Azoto-
bacter and the anaerobic Clostridia. Recent studies have shown that blue-
green algae can do the same things in the aqueous environment (l). When
such organisms die and decompose, the nitrogen is released as ammonia to
the environment.
There are a great many organisms that will attack nitrites or nitrates
and reduce such salts to ammonia for the purposes of obtaining nitrogen to
build protoplasm. This, of course, takes energy which must be put into the
system, obviously from other sources. Many organisms will also denitrify.
The step of denitrification as indicated on the chart is usually carried on
primarily for purposes of obtaining oxygen. This step, too, would require
energy from other biochemical systems in order to proceed. The denitrifi-
cation step would take the soluble nitrate or nitrite, and produce nitro-
gen gas as a final product. This mechanism is the only technique which has
been identified to date as returning the nutritive building blocks of fer-
tilizing forms of nitrogen back to the original source of the nitrogen,
namely, the atmosphere.
The history of the study of the nitrification process is extremely in-
teresting for it details some of the most tedious research work done by
early microbiologists in the formative years of the science of bacteriology.
Careful study of their research is quite worthwhile for it illustrates facts
which we seem to be rediscovering today.
In 1877 Schloesing and Muntz, in a very simple experiment, demonstrated
conclusively the biological origin of the nitrification process (2). They
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used, for this purpose, a tube 1 m long filled with sand and chalk, pre-
viously sterilized by incineration. Sewage water was poured daily into the
upper end of the tube. For 20 days the ammonia content of the effluent re-
mained constant. Then suddenly nitrate made its appearance and the ammonia
content fell to zero. The nitrification process once started, continued for
four months and then the investigators tried the effects of disinfection on
the reaction and a current of chloroform was drawn through the tube. This
had the effect of killing the organisms and once more ammonia came through
the tube. Nitrates were then restored by the application of washings from
garden soil. These experiments noted that alkaline conditions were neces-
sary for the production of nitrification and that the reaction required a
plentiful excess of oxygen. It should be noted that their column contained
chalk, calcium carbonate, and in addition that it took 20 days for the ni-
trifiers to sufficiently establish themselves to produce good nitrification.
As a result, it seems apparent that these are slow growing organisms in con-
trast to many other bacterial forms, as for example the ammonifiers in the
experimental tube (such organisms showed their effects the first day). Ni-
trifying organisms, however, could not be isolated by experimenters for many
years, though many investigators tried. Somehow or other, this step seemed
to be unexpectedly difficult.
Winogradsky was the first to become convinced that the gelatin plate
method which had proved so successful for the isolation of disease germs was
unsuited to the isolation of nitrifying organisms. He, therefore, tried an
extremely simple liquid substrate consisting of a water solution of four in-
organic salts plus potassium tartrate which was to be the source of carbon
(3). No growth at all was experienced. He then proceeded to eliminate first
one and then the other of the items from the medium with no growth resulting
until finally he left out the potassium tartrate. He was then immediately
gratified to see the culture produce intense nitrification.
Subsequently, then, Winogradsky employed a solid medium in which the ap-
propriate solution of salts was solidified by silicic acid. On this so-
called silicate jelly, colonies of nitrify-
ing organisms alone developed and could
easily be obtained free from other bacteria.
When streaked on a slide and stained, the
organism Nitrosomonas appeared to be a flag-
ellated rod, Figure 2. A typical medium for
isolation of nitrifying organisms has been
given by Heukelekian (U). To a liter of
distilled water add:
Ammonium bicarbonate - 0.2 gram
Dipotassium phosphate - 1.0 gram
Figure 2. Nitrosomonas. Sodium chloride - 1.0 gram
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Magnesium sulfate - 0.5 gram
Ferrous sulfate - trace
Into such a medium one would introduce his garden soil, sewage, acti-
vated sludge, etc., incubate for a period of time, and after repeated trans-
fers into successive tubes of this medium, the nitrifiers alone would per-
sist.
Reference again to Winogradsky's experiments indicates that he observed
that the oxidation of ammonia to nitrite always preceded that of nitrite to
nitrate; and that, as a rule, the nitrate did not begin to accumulate in
considerable quantities while any amount of ammonia remained unoxidized.
Winogradsky concluded that two organisms, or at least two groups of organ-
isms were concerned in the nitrification process. By setting up his inor-
ganic substrates, with first ammonia but no nitrite and second with nitrite
but no ammonia he did succeed in isolating two types of organisms.
While these differed morphologically according to the part of the world
from which they came, all seemed to be alike in their chemical behavior
in the requirement of the same substrate conditions. Namely: these are,
the presence of a salt of ammonia or nitrite, strongly aerobic conditions,
and the presence of carbonates in the medium. Under proper conditions,
therefore, the reactions are catalyzed by the organisms with the production
of a great deal of energy. The first step from ammonia to nitrite produces
79,000 cal/mole, while the second step of nitrite to nitrate produces 21,600
cal/mole (based on heat of combustion). Meyerhof has shown that the organ-
isms manage to utilize about 5% of the energy released by the reaction and
that approximately 95% of the energy liberated appears as heat (5). It is
this fact that is responsible for the extremely low growth rate of nitrify-
ing organisms. In turn the low growth rate makes the development of useful
amounts of culture a difficult step. It is at this point that the potential
conservative features of the rotating disc system suggest its use in study-
ing nitrification.
DESCRIPTION OF BIO-DISC PROCESS
Prior to 1967, there was little information or familiarity in the U.S.A.
with the bio-disc system of waste treatment. At about that time, pilot
plant work was undertaken on several fronts which eventually led to full-
scale adoptions and a better knowledge of the bio-disc process (6-9):
The use of the bio-disc in Europe, however, and particularly in Germany
has been quite extensive, and over 700 installations (some with more than 25
years of experience) are presently in operation. Most of them are small,
but the municipal plant at Donauischigen, West Germany, serves about
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100,000 people.
In essence, the bio-disc process consists of a series of closely spaced
discs mounted on a shaft which in turn is supported just above the surface
of the waste to be treated. The shaft and associated discs rotate slowly
(2-6 rpm) so that each segment of the disc pack is alternately submerged to
adsorb food and then raised out of the waste into the air for oxidation
purposes. The waste passing between the discs flows parallel to the adja-
ce"nt disc surfaces which support a luxurious biological flora. The discs
rotate slowly but impart a lifting action through the drag forces developed.
This head imparts a pumping action to the liquid, which in turn is induced
to circulate numerous times over the submerged quadrants of the discs in
passing through each stage of treatment. Incidently, it is unimportant
whether the disc shaft is transverse to the flow pattern or parallel to it.
The velocities of the fliud induced by rotation of the disc-pack are domin-
ant over any velocity created by the flowing liquid. Likewise, there may be
one or several stages of discs on one shaft. As long as the tank itself is
compartmented to fit the stages needed and the speed of rotation is governed
by the critical stage, the system will perform optimally.
When several stages of discs are utilized, the many narrow pathways
through the total unit are long and tortuous and the process in general can
most simply be described as being a horizontal trickling filter.
If the biomass exposed to the waste is scraped off the discs at one or
more points, it is possible to estimate the amount of growth involved in the
process. It is always heaviest in early stages and lighter in later stages.
In typical situations, concentrations of over 100,000 mg/jl, have been mea-
sured. Normal patterns however, indicate wide differences between stages
and within stages. Volatile solids are usually low indicating that some
aerobic digestion has taken place.
In summary, the bio-disc process is normally a secondary treatment sys-
tem. Detention periods vary from about 7 min/stage to 30 min/stage. The
process has a low F/M ratio and yields good BOD removals. There is a sludge
developed which represents sloughings from the disc system. These sludge
solids must be removed by a process of clarification. The sludge settles
easily and rapidly and disposal can be affected by any technique normally
used in trickling filter technology. In operation, the bio-disc has the
head loss characteristics of the activated sludge process, and yet there
are no associated problems of recirculation or pumping; bulking, and foaming
are completely eliminated. Of course, the piping, valving, pumps, and,
metering problems associated with the above are likewise eliminated.
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HISTORICAL DEVELOPMENT OF RBS
A recent paper presents a brief historical review from which the follow-
ing has been extracted with a few modifications (6).
The rotating biological disc is the accumulation of many separate
but related ideas. In Europe its designation of "Immersion Drip
Filter" is credited by Hartmann to Professor Pb'pel (10). In this
country in recent years the unit has been variously referred to as
the RBC (rotating Biological contractor), the RBS (rotating bio-
logical surface), and bio-surf. Buswell evaluated a unit of this
type back in 1929 and he referred to the unit as a biological wheel
(11). Apparently an experimental unit was developed by Paige and
Jones Chemical Company under patents held by A. T. Maltby filed in
October of 1928 (12) and granted June 23, 1931.
According to Hartmann (10) the original thought behind the unit
should be credited to Travis who in 1901 tried to increase the ef-
ficiency of his "Hydrolytic tank," a precursor of the Imhoff tank,
by hanging thin wooden strips in the settling compartment. These
strips he designated as "colloid catchers," and he assumed that
through the mechanism of adsorption, the cloudy nonsettling portion
of the sewage could be removed. After a period of accumulation the
solids adsorbed on the wooden slats were supposed to reach a thick-
ness and weight such that they would slough off the slats and fall
into the digestion hopper. Unfortunately, while the solids did
accumulate they didn't always slough. In addition, decomposition
of the older portions of the deposits invariably reduced the qual-
ity of the tank effluent. Just after the slats were cleaned, the
tank effluent was observed to be best.
From such observations came two divergent ideas. Buswell was con-
vinced that the slime was biological in nature and that its rather
immediate removal from the slats was important. To this end he
proceeded with experiments which involved shaking the slats. The
idea of motion of the biological support finally culminated in the
biological wheel and the Maltby patent.
Along a somewhat different vein of thought, C. C. Hays of Waco,
Texas, worked out the principle of contact aeration. His basic
premise was that decomposition of the older deposits of slime
could be prevented with the presence of diffused air below the
wooden slats. In practice, the wooden slats became cement-
asbestos sheets. While in this country the Hay's process was
known as contact aeration, in Europe the process was called an
immersion filter. To the experts there, the idea merely involved
7
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a trickling filter which was completely immersed. From this be-
ginning, it was a logical step some years later for Professor Popel
to view the bio-discs rising from the waste with sewage dripping in
thin films over the emerging slime and to conclude that this appa-
ratus should be called an immersion drip-filter (Tauchtropfkbrpern).
In this paper, further references to the unit will designate this treatment
device as a rotating biological surface (RBS).
Buswell's report of 1928 (ll) concluded that there were three major ad-
vantages of the RBS.
(l) The actual area occupied by the unit was about 1/10 of that
required for a standard rate trickling filter.
(2) The power cost was low compared to activated sludge.
(3) Nitrification was accomplished.
To bring this history up to the present, it must be stated that European
discs are 1, 2, and 3 m in diameter and about 12.5 mm thick. Discs of the
3 m dimension were briefly installed in the U.S.A. These shifted due to
competitive forces to 3.3-3.5 m (11-11.5 ftj discs also 12.5 mm thick. This
change was short lived and has culminated in a much thinner polyethylene de-
formed disc. (The deformations augment the area and generate the necessary
stiffness in the thin sheets.)
BIOLOGICAL NITRIFICATION USING RBS
While the major thrust of this research has been to study the applica-
tion of the RBS to the nitrification of high rate trickling filter efflu-
ents and sewage lagoons, nevertheless some aspects of the basic nitrifica-
tion mechanism have unavoidably been interjected into the study. These con-
cepts are probably of wider application than to the RBS operation alone.
Nevertheless nitrification on the RBS is the primary objective.
Buswell's work in 1929 referred to the fact that nitrification took
place with the biological wheel (ll). Unfortunately no figures were given
by which the completeness of the reaction could be measured. The 1967-68
work previously referred to (6) indicated strong nitrification at reduced
flow loadings 52 ^/m^/day (for settled domestic sewage using three stages
of treatment). Much additional evidence has suggested that some nitrifi-
cation would take place on ah RBS unit. The question therefore raised was,
to what extent would the reaction proceed, how environmentally sensitive was
the response, was the culture subject to wash-out at high rates of flow and
-------
could it be destroyed by shock loads (13-18)?
Certainly logic would dictate that a culture fixed to a rotating surface
could be much more dependable and easier to utilize than would such a cul-
ture if it were free in an uncontrolled suspension. On the other hand, it
might be anticipated that the lag time in start-up of a disc in comparison
to a suspended culture system could be greater. This might be expected
since the raw disc system must induce a relatively high shear region immedi-
ately adjacent to the disc. Nitrifiers are not noted for heavy encapsula-
tion and as a result much of the seeding the disc receives could wash away
rather than becoming attached.
In contrast a system maintaining a relatively modest level of chemical
or biological floe would tend to trap more of the seed organisms. There-
fore, in this research it seemed important that start-up time should be ex-
amined. On the other hand, direct comparison of the disc system to sus-
pended culture systems would have to be considered beyond the scope of the
work.
There was no question initially relative to the need for seeding espe-
cially when no seed was present in the influent (such as in a laboratory
system). However, the acceptable pattern for optimally seeding such a sys-
tem seemed to be quite unclear. Other related questions were also of ob-
vious importance. For example, in this connection, how significant is pH
and alkalinity? If a critical level for these factors exists will its ab-
sence affect seeding materially and might' not this fact prevent or retard
start-up?
The present project was inaugurated January 6, 1975, and designed to
run for two years during which time two types of municipal waste plant
effluents would be utilized as previously noted. How would their effluents
respond to the RBS when the process was added as a pilot unit at the dis-
charge end of each type of plant? As a result of the facts just presented
the nature of the treatment plants and their effluents became critical
parameters in the research as it developed.
-------
SECTION 2
CONCLUSIONS
Experiences with an underloaded, high-rate trickling filter and a two-
stage, flow-through lagoon indicate no difficulty in start-up of a
second-stage nitrification using the bio-disc.
The ammonia-N concentration was never appreciable in the lagoon effluent
at Genoa,, Ohio (two-stage, flow-through lagoon). When a synthetic ammo-
nia feed was applied to the pilot plant, the discs responded by gener-
ating a culture of nitrifying organisms.
High algal counts, low ammonia levels, precipitating calcium carbonate,
and extremely low temperatures forced curtailment of the work at Genoa.
The Saline, Michigan Wastewater Treatment Plant (high-rate trickling
filter) had a respectable ammonia-N content in its effluent at all times
(avg. l6.3 mg/j; as N) . The bio-disc (RBS) readily developed a good
nitrifying culture. The system should be rated excellent as a means of
accomplishing the objective of nitrification.
Over the two-year operating period of this research project, 0.6 m and
1.2 m disc systems (RBS) were operated in parallel. The results in all
cases were similar enough that they could have been produced by one
system.
Laboratory units never performed like the field units in terms of start-
up, biomass buildup, uniformity of removal, and environmental responses
dependent on bio-film thickness. True performance research then should
be carried on in the field with actual wastewaters and normal seeding.
The flow testing range of this work extended from 0.25 gpd/ft2 (10.2
^/m^/day) up through 6 gpd/ft^ (24U ^/m^/day) on six stages of discs.
Eemoval of ammonia-N exceeded 70% at all loadings.
Results indicate that for a given area of discs, the more stages used
the more consistent the results.
10
-------
9. Short-term environmental changes versus long-term changes are indicated
as needing better definition.
10. pH and alkalinity relations are shown to be typical of suspended culture
nitrification work.
11. The weight of ammonia-1 removal by a given area of discs increases as
the flow increases up to a limiting value of 3 £./m2/day.
12. Speed of revolution was checked for optimum oxygen uptake conditions,
3.5 mg/,0 of D.O. in the bulk fluid seemed to be a useful figure. At
and above this level, sufficient D.O. existed in the bulk fluid to pro-
vide the driving force necessary to satisfy the requirements of the
bio-films developed in this work.
IJ. The diffusional limitations of the bio-film were demonstrated in sev-
eral ways. At present, the nitrifying biomass in RBS work cannot be
defined except by approximation.
lU. The response of a normal series of bio-discs to a shock load is disap-
pointing, the problem being one of understanding the nature of the
nitrifying organisms more than anything else.
15. A.simplified kinetic approach to the bio-disc problem appears to be
necessary at this time because of the problems encountered in defining
biomass and diffusion.
11
-------
SECTION 3
RECOMMENDATIONS
FIELD WORK
1. It Is important that continued work in the field be carried out for pur-
poses of longer operational patterns at increased flow levels.
2. Field study of multistage units should likewise be continued to further
define the factors governing the employment of staging. These factors
will influence further development.
3. Alternation of flow by automatic valving may yield desirable factors for
future study under some conditions of flow or loading.
k. Optimization of biomass weight and thickness either chemically or mechan-
ically may lead to control of diffusional problems.
5. Once the biomass has been optimized, then fine tuning of environmental
conditions would be quite fruitful. Potential exists for such items as
D.O. control of bio-disc speed and maximizing driving force by control
of the ammonia-N level in the first and second stages of discs. These
and other such concepts will produce worthwhile modifications to an al-
ready highly dependable nitrification device.
LABORATORY WORK
1. The bio-film is still a major problem in the use of mathematical models.
Controlled feeding in the laboratory and extensive analysis of the slime
layers developed should enable the separation of autotrophic and hetero-
trophic activities and the definition of the interaction and inhibitions
generated.
2. A similar extensive study into the nature of the mechanism by which the
organisms attach themselves to a surface would be very useful.
3. Following optimization, a study of toxicity and inhibitory compounds
would be extremely fruitful.
12
-------
SECTION 1).
EXPERIMENTAL PROCEDUEES
SALINE WASTE TREATMENT SYSTEM
The Saline Waste Treatment Plant processes about (3.800 m^/day) o£
essentially domestic wastes. The wastewater receives grit removal
and primary clarification. Chemical is added'to the grit chamber for phos-
phorus removal. After primary clarification the waste passes through a two-
stage trickling filter, final clarification and thence to sand filtration,
chlorination and discharge to the Saline River (see Figure 3). Ther'pilot
unit for the RBS system was inserted between the final clarifiers and the
sand filters. A submersible pump was placed in a channel between these two
treatment units and a plastic hose was used to conduct the necessary flow to
the RBS site. Discharge from the RBS was run by a plastic pipe back to the
final clarifiers.
This pilot plant influent was a typical secondary effluent and was
sampled about three times per week during pilot runs. The city water orig-
inates in wells and as a result is fairly stable and uniform in quality.
There is a large industrial plastics operation in the town and as a result
of a strike a marked drop in ammonia level was noted for the duration of the
strike. Other than that instance the level of ammonia was high but seemed
to be higher in winter and lower in spring and summer. Monthly, high, low,
and mean values are given in Table 1 and plotted in Figure 4.
Reference to Figure k indicates the existence of a sinusoidal trend in
the influent ammonia concentration. At least for the period of study, peak
concentrations were reached in January or February and the lowest concentra-
tion was reached in July. No ready explanation can be offered for this ob-
servation. The possibility exists that sludge handling operations could be
responsible for the apparent trend and that a change in this operation could
alter the entire situation.
If the temperature cycle of the pilot plant influent is taken into ac-
count (see Figure 5), it is obvious that the highest ammonia concentrations
and the lowest temperatures coincide and similarly that lowest ammonia con-
centrations occur with the highest temperatures. This produced a difficult
13
-------
Raw Waste
Screen
Wet Well
1
FeCI
Pumps
Aerated Grit
I
Polymer
Splitter
Primaries
Zrect-lcirc.
Sludge
Saline River
Digesters
-G^
........ / r
Sludge
Press
Land
Fill
Figure 3. City of Saline Wastewater Treatment Plant.
lU
-------
TABLE 1. INORGANIC NITROGEN FRACTIONS IN SALINE PILOT PLANT INFLUENT
Year
1975
1975
1975
1975
1975
1976
1976
1976
1976
1976
1976
1976
1976
1976
1976
1976
1976
1977
1977
1977
Month
Aug
Sept
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
June
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
Mar
No. of
samples
7
9
13
8
7
11
10
5
4
6
8
6
10
11
14
3
24
5
8
13
181
NHj-N mg/£
max. min.
16.2
14.0
20.0
20.0
19.7
22.2
19.8
15.6
19.0
13.8
21.5
17.8
23.0
26.8
24.1
24.1
31.3
23.3
30.3
23.8
9-4
11.7
9-4
12.6
12.8
13.4
5.4
9.8
15.0
8.6
8.0
6.9
7.7
10.0
8.9
15.2
11.8
16.8
14.8
15.0
x =
avg.
12.2
12.6
14.2
15.6
15.4
16.6
13.1
12.1
16.4
11.5
13.8
10.4
13.0
16.2
15.2
19.3
21.3
20.5
22.5
18.9
16.3
(N02-N + NOj-N
mg/j)*
avg.
3-3
1.7
5-7
6.4
4.6
3.3
2.8
1.5
4.6
3.8
3.1
4.5
3.0
4.4
4.1
4.5
4.5
4.1
3-0
5.^
3.9
*The sum of NO£-N + NOx-N will be referred to as Nox at further points in
this report except when looking at NOg alone.
15
-------
26
24
22
20
, 18
UJ
8 '4
oe
5 10
o
2 8
6
4
L=0.25
0.5
1.0
1.5 2.0 2.5 3.0 4.0
6.7
3.5 gpd/sq.ft
L=10.2
20.4
40.7
61.1 81.5 101.9122.2163.01 1244.4
2O3.7
FLOW LOADING RATES
142.6 J/m2-d
Influent
Legend:
• Average Cone, for each Month
Average Cone, for each Run
Effluent
7 8 9 10 11 12 1
- 1975 - M
2345678 9 10 11 12 1 2 3 4
1976 - M« - 1977
Figure k. Summary of nitrification performance versus hydraulic loading rates at Saline, Michigan.
-------
H
LJ
24
22
20
18
16
14
<
cr
£ 12
8
40.7
FLOW LOADING RATES 5.C
1.5. 2.0 12.5 3.0 4.QI T 6.0
61.1**81.5l1oij£l22.2
Ife
3.5 gpd/sq.ft
142.6
203.7
Legend:
• =Temp. (daily)
/."
= Duration of Run
89 10 11 12 1 2 34 5678 9 10 11 12 1 234
1977-
Figure 5. Summary of temperature values versus hydraulic loading rates at Saline.
-------
situation in the Saline pilot plant during the final run. Certainly the
unit was stressed severely since the run took place at the peak of the ob-
served ammonia concentrations applied to the pilot unit and at the low point
of the yearly temperature.
Figure k also indicates the effluent concentration of ammonia values ob-
served. The results during the final run do increase because of the above
factors. One significant feature however, is the total amount of ammonia re-
moved.
This factor remains exceptionally high in spite of the adverse condi-
tions noted. This circumstance will be referred to later in this report.
Table 1 also indicates that the pilot plant influent generally contained
a moderate but continuous level of nitrate. It should be emphasized that
this fact seems to be independent of temperature. This observation implies
that a low rate of nitrification exists at all times in the trickling filter
portion of the treatment cycle. Table 1 gives the monthly mean values for
(nitrate + nitrite) over a period of the study. The average for l8l obser-
vations was 3-9 mg/,£ • The consistent presence of substantial quantities of
oxidized nitrogen suggests that seed organisms were continuously present in
the influent of the RBS system. As a result the pilot plant responded de-
pendably in all respects which were considered a function of seeding. Start-
up or a shift in operating level presented no problem or challenge to the
Saline RBS system. Any change in procedure required time to permit biomass
adjustment, but the plant in general appeared healthy and performed well
during the two-year testing period.
GENOA WASTE TREATMENT SYSTEM
Genoa, Ohio was chosen as the sewage lagoon system to be studied. The
city lies about 72 km southeast of Ann Arbor. Treatment consists of two
facultative, flow-through lagoons, each having an area of 2.7 ha and a BOD
loading of 28 kg/ha. The plant effluent is discharged directly to the
Tousaint River a few kilometers from Lake Erie. The final discharge is not
chlorinated. The design data is indicated below in Table 2. The plan view
and cross section of this system is shown in Figure 6. As is shown in the
figure, the RBS pilot unit was inserted in the plan by placing a submersible
pump in the final effluent manhole. A sandbag provided, the necessary sump.
Once assembled, the pilot unit was placed directly above the manhole and a
shed-like structure was built over the whole unit.
18
-------
b
6S
m
r
t>yi -(
J
Pond "A"
/NyA
\S^J
Pond "A" .
Effluent ^
Transfer
Line
b
f
•
t
6"
Influent
i
"CD
_ i
o\ ^^™
*•» ^«"
Jj °^
Pond"B"
h
r
4
a
SQ11- 0"
XRaw Sewage
8" Force
Main— -7
'
A
4 Pilot Plant
j I 1
^Fjnai Effluent
Slide Slopes=3:l
EL.624.0'
^4'.0'^r 543'-0"
Section A A
Figure 6. Genoa wastewater treatment.
19
-------
TABLE 2. DESIGN DATA - GENOA, OHIO
Initial Operation - 1966
Design Population - 2500
Population Served - 2000
Estimated Flow - (0.2 MGD) 756 m.3/day
Organic Loading - (2^0 Ib BOD/day) 109 kg/day
Pond Dimensions - (5^3 ft x 5^3 ft x 5 f t SWD)
165.5 m x 165.5 m x 1.5 m SWD
Pond Area - (6.77 acres each) 2.7 ha
Primary Pond Loading- (1.2 Ib BOD/1000 ft2/day or 50 Ib/acre/day)
28.k kg/ha
Detention - 88 days total
Disinfection - None
There was some question relative to the presence or absence of ammonia
in this waste effluent when the project was initiated but the work was pur-
sued in order to be quite certain of the treatment plant characteristics and
the effluent derived therefrom.
Intense algal activity was prevalent when the pilot plant was activated.
As a result no ammonia was observed in the Genoa effluent. Calcium carbon-
ate deposition was heavy. In fact the submersible pump feeding the pilot
unit was totally plugged with deposits almost immediately after initiation
of activity. Maintenance became a very difficult problem.
It was hoped that with the coming of fall weather ammonia would begin
to pass through the system. On that basis, ammonium chloride was added to
the pilot plant disc system by means of a small chemical feed pump. It was
thought that this would encourage the growth of a nitrifying biomass on the
discs and thus the unit would be ready if and when ammonia did appear.
Data on Genoa is sparse. That which was accumulated is presented in
Appendix C. The appearance of ammonia was late in the winter, was low in
concentration, and never without extensive algal biomass. Freezing, plug-
ging, and supplementation of ammonia were constant problems and seemed to
preclude the development of good data. This unit was therefore abandoned.
PILOT PLANT DESIGN
The first step in the research plan was to design an RBS pilot unit
which would provide sufficient size and flexibility to yield the desired
information. The unit had to be large enough to yield data which could be
20
-------
extrapolated to a full scale prototype. It had to be large enough so that
continuous sampling of flow between stages would have no effects on any ob-
servations that might be made. At the same time each unit had to be easily
transported by truck, require no more than a 100 -V lighting circuit as an
electrical service and have maximum flexibility.
The basic disc material in commercial units now consists of a thin
polyethylene which has been deformed for added strength and rigidity. These
deformations do provide added area, but for purposes of flexibility in re-
search, can be dispensed with. Flat discs are more general, can be easily
added or- deleted, and spaced as needed in the tankage provided. Further, if
scraping of: unit areas for biomass determinations was necessary at any time,
the flat disc would lend itself better to such use. As a result, the disc
material was cut from 1/2 in. (12.7 mm) polystyrene stock at h Ib/ft^ density
(6k
Previous disc research had demonstrated that diameters of 0.15 m (6 in.)
and 0.3 m ( 1.0ft) were inadequate to truly distinguish the important factors
in disc loading. In these cases the agitation produced at the water surface
dominated the results rather than diffusion into or out of the biological
film. Thus larger discs were in order.
Two -ft diameter discs (0.6 m) appeared to be the smallest acceptable
units, but k-ft discs (l.2:m) were chosen for several reasons. First, as
previously mentioned, when samples are taken continuously at each stage of a
six-stage unit and the overall flow is low, there is a substantial alteration
of flow and mass of substrate between the first and last stages due merely to
the diversion of flow at each stage for samples. Second and more importantly,
the rotating elements and the sewage flow would have to be the main source of
heat within the pilot plant space in order to resist freezing during winter
months. Four-ft units (1.2 m) would involve more flow and the heat provided
would be proportionally higher. This later factor was of immense importance
at Saline. However, it did not save the unit at Genoa from freezing up.
The use of U-ft (1.2 m) discs provided an area of 188 m2 of surface.
This area was loaded at rates from 1/h to 6 gal/ft2/day (10 £/m2/day to
2kk ^/m2/day) . This range of flow loading rates was not anticipated ini-
tially. In fact the original plan of testing proposed the highest flow rate
at 2.0 gal/ft2/day (8l ^/m2/day) . This would be for six stages and would
therefore be 12 gal/ft2/day on the first stage. However, at this level of
flow nitrification was easily accomplished and it became necessary to go
higher and higher in order to cover the full range of bio-activity. Testing
had to be terminated however at the 6-gal rate because time was running out.
It would have been better to raise the rates to 8 and 10 gal/ft2/day levels
but circumstances would not permit this range of testing.
21
-------
Figure 5 shows each flow loading tried and. the duration of each test.
If the testing had proceeded as planned, the 2 gal/ft2/day test would have
been completed by May and subsequent testing would have been carried out
during the warm months of the summer and fall with time for checking the re-
sults during the winter. As can be seen on Figure 5, the final test for
checking purposes was carried out during the worst of the winter weather.
Initial pilot plant design was influenced by prior experiences with the
bio-disc in which biological oxidation of organic carbon was studied. Such
work indicated that higher efficiencies of removal and narrower ranges for
standard deviation of performance were obtained when a fixed area of discs
was used in a series mode rather than in parallel. It seemed logical that
such a factor could be present in RBS nitrification as well. As a result the
pilot plants were constructed in rectangular tanks with one shaft and one
drive motor. Six stages were available through the use of movable parti-
tions. Fourteen discs were placed in each stage. But it was expected that
28 discs might be used in each of three stages or U2 discs in each of two
stages or 84 discs in one stage if any of these configurations were needed.
As soon as the data began to accumulate, it became evident that no time would
be available for tests involving the rearrangement of partitions. However
the results of such testing could be estimated quite easily from the major
data set of the main test series.
Figures D-l and D-2 in Appendix D show the essential layout of the pilot
units. Table D-l of Appendix D gives the reactor specifications. It should
be noted that Figure D-2 shows the sampling port designations. These corre-
spond with the data as tabulated in Appendixes A and B.
SAMPLING
Samples consisted of 5• &-£'composites made up of hourly increments, each
of 117 ml of test fluid settled for 1/2 hour and placed in a plastic jug con-
taining HgCl2 as a preservative. At the end of the 2h-hr test cycle the jugs
were picked up and analytical tests were run on each composite. Ammonia,,
nitrite, nitrate, pH, suspended solids, and COD were run routinely.
The solids accumulated during the half hour setting were accumulated in
a drum. These were agitated and sampled for the total suspended solids
(sludge) generated by the system. The design of the sampling device is
shown in Figure D-J in Appendix D.
All tests were carried out in accordance with Standard Methods (19) or
an approved adaptation for the autoanalyzer (20).
22
-------
CONSTRUCTION
The tankage was subcontracted to a local welder. The flat discs were no
longer available on the market but were still available from scrap. The
tanks were trucked to the sites and set up on concrete blocks. Electrical
services and plumbing were ditched in alongside existing tanks to provide
the necessary heat during the winter to minimize freezing. When all was in
place, a shed was built over the entire unit. The shed was insulated, lined
with external plywood, roofed, and painted. The flooring consisted of steel
grating which was available at the moment. The grating was blocked up about
8 in. above the ground. This permitted spills and leaks without trouble;
new hose connections could be made easily and other problems could be simply
solved. For example sludge was accumulated in seven drums placed alongside'
the reactor tank. Each drum was half of a 55-ga-L steel barrel. After the
sludge sample was taken, the barrels had to be drained before the next sam-
ple was accumulated. This was accomplished by placing a wooden trough be-
low the grating. Each drum was drained to the trough by pulling a rubber
stopper. The trough drained back into the treatment works.
The shaft was set up in the laboratory and the discs carefully glued in
place with silicone rubber. A keyway on the shaft assisted in anchoring each
disc. Once mounted and dried out, the shaft was trucked to the site and
mounted above its tank. After some adjustment of partitions the entire unit
was placed in operation.
23
-------
SECTION 5
EXPERIMENTAL OBSERVATIONS
GENERAL
Initial study of the Saline project suggested that certain portions of
the proposed study might result in destruction of the nitrifying flora. If
such a circumstance took place during cold weather, it might well be a month
or more to reestablish production. Such considerations seemed to demand a
back-up unit.
For the above reasons,, the k-ft (1.2 m) pilot unit was set in operation
in parallel with a 2-ft (0.6 m) unit which was similar hydraulically. (Sev-
eral of these 2-ft (0.6 m) units were in existence when this research was
envisioned.) A second such 2-ft (0.6 m) unit was set in operation in the
laboratory utilizing a synthetic waste and seed from the sewage plant.
Data from the small and large units at the Saline sewage treatment
plant appeared to be homogeneous. This was so outstanding that the data for
one flow loading test has been taken from the small unit. This became nec-
essary when the large unit broke down. Its nitrifying culture was seriously
hurt and data could not be taken for a one-month period. In order to save
time the small unit, which continued to operate, was used.
It can be stated here that the laboratory unit never performed like the
field units. Every attempt was made to produce similar results. To date it
has not been possible to develop total similitude. Items like biomass,
ammmnia-N uptake rate, start-up time, continuity of performance, etc., were
considerably different between laboratory and field. Such values might be
classed as absolute measurements. Relative measurement which seemed to be
more nearly correlatible were responses to pH, alkalinity, temperature, dis-
solved oxygen and presumably toxic effects. Reasons for differences will be
discussed in more detail later. Suffice it to say at this point that it
would appear that loading values can at present only be obtained through a
study of field installations. At Saline, the 0.6- and 1.2-m pilot units
were operated continuously during the life of the project for as much load-
ing data as could be gathered.
-------
Unfortunately more time would have been very helpful. The range of
testing needed to fully cover the necessary loadings was entirely unexpected.
As a result, some of the higher loadings were tested for too short a period
to get a true measure of performance.
Through experience it became clear that the fastest way to activate a
disc system was to start-up at low flow rates with plenty of seed. When
oxidation of the ammonia begins to take place the flow can be increased
slowly. It should be noted that the original overall experiment was set up
this way. 'This was fortuitous. The actual experimental design was the re-
sult of the feeling that at some point of flow loading the nitrifiers would
cease to function, merely because there would not be enough time for them
to carry out their oxidation process. As a result the flow was increased
slowly so as to reach this point stepwise. It turns out that the organisms
can function quite well at extremely high rates of flow. The highest rate
attained in this work was 2hh ^/m2/day on six stages. This translates to
lk6U ,£/m2/day on the first stage and still the nitrifiers were oxidizing 20%
of the ammonia passing through the stage. The point was never reached
where activity ceased.
A total of eleven runs on flow variations were carried out. Table 3
gives the various flows and indicates run numbers and location of data in
Appendixes A and B of this report.
EXPERIMENTAL DESIGN
The experimental work originally envisioned involved operating the pilot
system first as six stages in series. That configuration was expected to
provide the best chance to capture nitrifiers as they passed the unit. Fur-
ther, many disc systems were known to nitrify well at or below a loading of
1 gal/ft2/day (UO ^/m2/day). As a result a loading of 0.25 gal/ft2/day (10
^/m2/day) was chosen as the best flow for activating the discs. It should be
noted that the loading here referred to is the overall loading for the total
system (see Table U). The flow loading at any previously selected point will
be found by dividing the total value by the percent of the total area in the
system up to that point. Hence if the total flow is 0.25 gal/ft2/day (10
J/m2/day) for six stages, the flow for three stages would be 0.5 gal/ft2/day
(20 £/m2/&8.y), for two stages would be 0.75 gal/ft2/day (JO £/m2/day), for
one stage would be 1.5 gal/ft2/day (6l ,g/m2/day).
25
-------
TABLE 3. OUTLINE OF ROTS PERFORMED AT SALINE
Appendix A Appendix B
Run Dates Flow data for data for
English Metric (HEt* + Noxt) S.S. & C.O.D.
10 £/m2/z + M>>) mg/^ as N.
26
-------
TABLE k. SURFACE DISTRIBUTION AND FLOW LOADING TO STAGES
Incremental
Stage
1
2
3
k
5
6
Incremental area
(ft2) or m2
(337)
(67*0
(1011)
(151*8)
(1685)
(2022)
31
62
93
121*
155
186
m2
m2
m2
m2
m2
m2
Percent of
total
17
33
50
67
83
100
flow loading
(gal/ft2/day)
or ^/m2/day
(1
(o
(o
(o
(o
(o
.50)
.75)
.50)
.37)
.30)
.25)
61
30
20
15
12
10
When a complete range of flow values is tested it becomes possible to
factor out the influence of staging. Reference to Table 6 shows for example
a loading of 3-0 gal/ ft /day which appears at the locations circled. These
points may be enumerated as follows (see Table 5)'•
TABLE 5. DATA LOCATION (3 gpd/ft2 loading)
Stage
1
2
3
Ij.
5
6
(gal/ft2/day)
Loading
(3.0) 122 £/m2/day
(3-0) 122 ^/m2/day
(3.0) 122 ^/m2/day
(3.0) 122 £/m2/day
(3.0) 122 j?/m2/day
(3.0) 122 £/m2/day
Data
table
A-2
A-3
A-U
A-5
A-6
A-7
Further examination of the tabulated data should establish the removal
efficiency associated with a constant flow loading and a varying number of
stages.
This experimental design also provides a means for determining the dis-
persion of values from which a prediction is made and a visual concept de-
fining ultimate quality for a given environmental condition.
27
-------
TABLE 6. DESIGN OF OVERALL EXPERIMENT
o>
Stage Factor A-lf A-2
1 6.0 1.5 |3.0
2 3.0 0.75 1.5
3 2.0 0.50 1.0
k 1.5 0.37 0.75
5 1.2 0.30 0.60
6 1.0 0.25 0.50
Flow
A-3
6.0
3.0
2.0
1.5
1.2
1.0
2
gal/ ft /day* (to the point)
A-U
9.0
U.5
3.0
2.25
1.8
1.5
A-5
12.0
6.0
U.O
3.0
2.U
2.0
A-6
15.0
7.5
5.0
3.7
15.0
2.5
A-7
18.0
9.0
6.0
^.5
3.6
3.0
A-8 A-9 A-10 A-ll
2h.O 30.0 36.0 21.0
12.0 15-0 18.0 10.5
8.0 10.0 12.0 7.0
6.0 7-5 9.0 5.2
U.8 6.0 7.2 U.2
U.O 5.0 6.0 3.5
*Miltiply all terms by kO.7 to-yield metric equivalents.
Tables A-l through A-ll will be found in Appendix A.
-------
FLOW LOADING AS AFFECTING NITRIFICATION
Construction, testing and correction of miscellaneous problems required
about 6-1/2 months. Operational testing began on August 1, 1975. Actual
start-up had taken place on July 2J. Spot checks were taken to note the
disc activation time.
Date Influent NH^-N Effluent NHj-N
7/23 10 = 3 JD&/£ 10.3 (start-up)
7/29 7-5mg/,g 3.5mg/^
7/31 8.0 mg/£ 1.0 mg/j?
8/01 9-5 mg/^ 0 mg/£
Apparently about nine days were required to activate the new disc system at
the first loading selected 0.25 gal/ft2/day (10 ,g/m2/day) .
This run will be referred to as run 1 and its data is reported in Tables
A-l and B-l of respective appendixes. It was important to have a grasp of
the performance and operating characteristics of the disc system, so the run
was continued from 8/02 through 10/15. Nineteen sampling days were covered.
Flow was set each day of adjustment by a valve on the discharge side of the
submersible pump. It was felt that with the head loss constant on the sys-
tem and the high quality of the effluent being fed to the pilot plant, such
control was adequate. Experience with the system revealed that a certain
amount of plugging of the valve took place. Low flow settings were hard to
hold but higher flows were easier to control. Each day the flow was mea-
sured volumetrically when samples were picked up. This flow is recorded in
column 2 of Table A-l in Appendix A. The flow was then adjusted to the cor-
rect value noted as the "flow loading." Actual flows through the unit re-
flect a variation between these two extreme values.
Examination of Table A-l in Appendix A shows the characteristics of the
data accumulated. For example stage 1 was removing 70% of the influent am-
monia leaving only 30% for the remaining five stages. Even so, readings of
less than 0.^ mg/£ NJfe were seldom if ever reached in the effluent.
Further, anomalies were frequently encountered. For example on August
26 influent ammonia was ih.k rag/Jl while the effluent of stage 1 was 1.9 mg/i
for 87% removal. On October 1 the influent ammonia was ih.h mg/J while the
first stage effluent was 0.8 mg/J for a 9^% removal. At the next sampling
period the influent ammonia was 13.2 mg/J and the effluent 13.5 for a zero
percent removal on stage 1 but the effluent of stage 2 was 0.2 mg/£ for a
removal over two stages .
29
-------
At first it might be assumed that something toxic to nitrifiers might
have been tributary to the Saline plant. However, whatever it was had no
effect on stage 2 and if the oxidized nitrogen fraction of stage 1 influent
is examined, it is found to be exceptionally high at 7.5 mg/,g. Obviously, no
toxic ingredient had affected the trickling filters. Regardless of the
cause of the problem it can be stated with certainty that the effluent of a
single stage is highly variable even when lightly loaded. The effluent of
the second stage however is much more uniform and the trend is continuous
with further stages (depending on the loading).
The following data are taken directly from Table A-l and reflect the
average of 19 values from each stage.
KPL-W
Influent Stage 1 Stage 2 Stage 3 Stage k Stage 5 Stage 6
x 13.4 U.I 0.7 0.5 O.k O.k O.k
a 2.6 6.1 O.h O.U 0.3 0.2 0.2
Since stage 1 seemed to be doing most of the work, the flow was doubled
to 0,5 gal/ft2/day (20 ,g/m2/day) . Again much the same pattern prevailed.
The anomaly previously noted, namely, the large drop in efficiency detected
in stage 1 was again apparent on 10/17 and 10/20. The additional flow still
did not provide sufficient substrate to load the unit and the last three
stages had little ammonia oxidation to carry forward.
Again the flow was doubled to 1.0 gal/ft2/day (hO ^/m2/day). This gave
a 6 gal/ft2/day (2kk ^/m2/day) rate over stage 1 and was assumed to be a
critical loading at least for the first four stages. The peviously noted
anomalies occurred again especially during January. However, the second,
third, and fourth stages made up for any deficiencies which developed in
stage 1 and even on January 26 when stage 2 had an 11.2 mg/^ influent and
11.k mg/& effluent, the effluent of stage 6 was a respectable l.U mg/£. It
is important to note that these anomalies will distort stage averages unless
a substantial amount of data is compiled.
While the testing to this time seemed to give an acceptable average of
0.5 mg/,0 on the fourth stage, there was no way to tell how much more load
the system might be able to take.
The flow was therefore raised to 1.5 gal/ft2/day (6l ^/m2/day) and then
to 2.0, 2.5, and 3.0. At this higher flow, the anomalies previously noted
began to work their way through the system. For example, on June 21 stage 1
had an ammonia influent of 21.5 mg/,0 and an effluent of 20.8 mg/£. Stage 2
30
-------
had an effluent of 17.3 mg/,g and stage 6 an effluent of 5.0 mg/^. Since the
series of tests had an average effluent at stage 6 of 0.? mg/£, it appeared
that the nitrifiers throughout the disc series were sick. Certainly an ef-
fluent of 5.0 iDg/ji is almost 10 times higher than might be expected. Out of
eleven test values observed in this series, three exceeded 1.0 mg/j because
of such upsets.
When the overall flow was raised to 1+.0 gal/ft2/day (l62 l/m2/day),
seven out of ten values exceeded 1.0 mg/£ of ammonia at stage 6.
Time was becoming critical at this point. So after a poor run at 5.0
gal/ft2/day (203 ^/m2/day), the flow was raised to 6.0 gal/ft2/day (2kk
^/m2/day) overall. This corresponds to 36 gal/ft2/day (lU6U ^/m2/day) on
stage 1 and was considered to be an extremely high loading level. Even so
results show that 50% of the observed values of effluent ammonia at stage 6
were still below 2.0 mg/,g.
Figure 7 shows the average ammonia removals per stage for the major
loading levels. Unfortunately, the sinusoidal temperature variations affect
these results and the ammonia concentrations tributary to the pilot unit
likewise affect the biomass.
Figure 8 is an attempt to normalize the varying ammonia levels at the
pilot plant influent. This gives a valuable set of curves indicating the
effect of staging and overall flow loading values involved in producing a
given percent removal. It should be remembered that these values are taken
from averages and that runs are more or less a month long.
2
Since the nitrifiers were not loaded beyond the 36 gal/ft /day (lh6h
i/m2/day) loading, it cannot be stated with certainty what the effect of
higher loadings would be. However, it seems logical that these results may
be extended a moderate amount if needed. For example, in Figure 8, it would
be possible to extend the 6 gal (2hk k) loading value to seven or eight
stages if it were necessary to reduce the effluent to about 10% ammonia ni-
trogen remaining (90% removal).
More than six stages at flow loading values less than 3 gal/ft2/day
122 ^/m2/day) would seem to be counterproductive because of the low rate of
NEfe-N removal beyond the fifth stage. Suffice it to say that Figure 8
seems to afford the best technique available to relate stages, overall flow
loading and efficiency of removal. With this nest of curves, it is possible
to set for 90% removal and to decide on the overall flow loading and the
number of stages desirable to achieve the desired level of removal.
In the reactor tank as tested, stage 1 has a capacity of 5^.7 gal
(206 z), and at the highest flow rate used had a detention time of 6.5 min.
31
-------
INFLUENT1 23456
NO. OF STAGES
Figure 7. Effects of hydraulic loading rate on nitrification at Saline,
32
-------
100
STAGE NO.
Figure 8. Ammonia removal normalized with regard
to influent concentrations.
33
-------
The detentions at other flow rates and the corresponding weights of nitrogen
oxidized in stage 1 are shown in Table 7.
TABLE 7. FLOW VERSUS TIME AND NITROGEN OXIDIZED IN STAGE 1
Overall
hydraulic load.,
gal/ft2/day
0.25
0.50
1.00
2.00
3.00
k.oo
5.00
6.00
Influent
flow,
gpm
0.35
0.70
l.Ui
2.81
k.2.2
5.62
7.02
8.U3
Stage 1
Detention time, Ib
min per
156
78
39
19.5
12.9
9.8
7.8
6.5
N oxidized,
1000 ft2/day
0.11
0.21+
0.55
0.79
0.58
0.5^
0.37
0.72
Neglecting the lowest two hydraulic loading values above (since they repre-
sent underloading), the N oxidized values of the loadings from 1 to 6
gal/ft2/day average 0.60 Ib N oxidized per 1000 ft2/day (3 kg/m2/day). The
time for this oxidation varied from 6.5 min to 39 min. Apparently within
these limits detention time is relatively unimportant. It should also be
noted that the maximum ammonia-N removal on stage 1 is developed at the 2
gal/ft2/day (80 ^/m2/day) loading value and does not increase beyond that
level. If removal is a. direct function of nitrifier biomass, then the
variable too must have reached its maximum level at that same critical flow
loading level.
AMMONIA LOADING AS AFFECTING NITRIFICATION
Reference to Table 7 shows that the consumption of ammonia by the ni-
trifiers increased up to a level of about 0.6 to 0.7 Ib of ammonia as N,
per 1000 ft2 of disc area in stage 1. Beyond that point no additional
ammonia was consumed by the micro-flora inhabiting stage 1. At the point
when this level of nitrogen was tributary to stage 1 the flow to the six-
stage pilot unit was 1 gal/ft2/day overall and the flow passing stage 1 was
6 gal/ft2/day. Table 7 indicates that a 600
-------
this level of removal requires a fixed area of support for the biomass which
is unaffected by flow, turbulence or end-products at least within the range
of testing covered in this work.
Figure 9 is a plot of the actual data for the work performed. It merely
shows ammonia applied in pounds and ammonia removed in pounds per day for
the system used. Each stage being 337 ft2 (31.6 m2) or 0.3U of 1000 ft ,
the graph could be altered by dividing each value by O.Jk which would put
the units in thousands of square feet. Similarly the graphs could be con-
verted to metric equivalents.
Without question the overall figure shows each stage taking its fixed
level of ammonia and no more. Further the line 0-A defines the asymptote
toward which the series of stages trend as the flow increases and the number
of stages increases. The slope of 0-A is 0.95/1.00 showing that if a design
requiring a fixed area of discs is laid out with a sufficient number of
stages, 95$> removal can be obtained.
The curves look so uniform that they might well be restructured to add
more and yet more stages and higher and higher flows. Logic dictates how-
ever that, there must be a limit at some point. Here, experience must be
depended upon for guidance.
It had been hoped that the Saline unit could have been driven past such
a point of critical loading. When the EPA indicated that no extension could
be given to the work, it was decided to stress a laboratory pilot unit past
the critical point.
It has been established that anomalies become more and more frequent as
the flow increases. A severe anomaly may seriously affect the entire unit
for a day or two. In the case of the laboratory unit and at the higher flow
values the unit does not come back easily or in some cases at all. In the
field, the unit seems to respond beautifully to an anomaly. A few bad sam-
ples may be produced but then the pilot plant returned to high efficiency
operation. Such work therefore had to be done in the field, or else remain
uncompleted.
STAGING
The flow loading, mass loading, and staging effects are so interrelated
in this work that a separate section on staging may seem slightly redundant.
However, staging effects should be stressed for purposes of adequate design.
As a result the following is offered.
If Table 6 (page 28) is expanded to include the results of the
35
-------
AMMONIA-NREMOVED, Ibs./day
0.2 0.4 0.6 0.8 1.0
0.4 0.6 0.8 1.0
AMMONIA REMOVED, Ibs./day
Figure 9. Mass loading and removal at Saline.
36
-------
tabulated data in Appendix A, Table 8 is the result.
TABLE 8. EFFECT OF STAGING ON NHj-N REMOVAL FOR CONSTANT FLOW
(3 gpd/ft2 loading)
Stage
1
2
3
1*
5
6
Loading
gpd/ft2
3.0
3.0
3.0
3.0
3.0
3.0
Source of
data
Appendix A
Table No.
A-2
A-3
A-4
A-5
A-6
A-7
NHj-N
percent
removed
70$
7ty
93%
91.%
9b%
93$
Standard
deviation
mg/,2
^.7
2.9
0.6
0.6
0.5
0.1
Obviously if a J.O gal/ft2/day (122 f/m2/day) flow loading is chosen
for design purposes, the disc area should be arranged in three stages or
more. The results as shown above indicate a 23$, improvement for three
stages over a single stage. The most important factor however would be the
effect on the standard deviation of the mean. This term in essence would
define the accuracy with which the defined average must be associated. Vir-
tual certainty (95$ assurance) would lie within ±2 0 of the mean value.
Examination of the 6.0 gal/ft2/day (2tik 2/m2/day) flow loading shows a
very similar trend. In essence the first and second stages show erratic
results. Three or more stages produce increasingly reliable results. When
all loadings are considered and placed on a chart relating hydraulic loading
per stage and percent ammonia nitrogen removed, Figure 10 results. Only
loadings from l/U-12 gpd/ft2 (10.-2-U88 ,g/m2/day) are shown in Figure 10
since removals at higher flows fall below the 60$ removal level.
Figure 10 indicates wide divergence for the first and second stages as
noted above. However, the third through sixth stages form an s-shaped curve
which crosses the critical percent removal levels at well defined flow
loading points. For example the following seem to be clearly indicated.
1. Three stages generate a somewhat erratic performance above
90$ removal. As a result, for a value such as 95$ removal,
the recommendation would be for four or more stages and for
flow loadings of 2 to 2.5 gpd/ft2 (8l to 102 f/m2/day).
37
-------
100
A \ '• T'- ^'
.— .—A. \ % \ *r
t —-U\
HYDRAULIC LOADING, gpd/ft'
Figure 10. Stage loading versus NHz-N removal efficiency.
38
-------
2. For 90% removal, the recommendation would be for 3.5 to
4.0 gpd/ft2 (110 to 163 ,£/m2/day) and four to six stages.
3. For 85$ removal, the recommendation would be for 4.5 to
5.5 gpd/ft2 (183 to 244 i!/m2/day) and four to six stages.
It should be emphasized that the lower values in the range of flow
loading represent a conservative approach while the higher values in the
range are a more liberal approach. Table 9 defines the limits of the exper-
imental work for the three levels of 85, 90, and 95$ ammonia-nitrogen re-
moval.
It must be remembered that these observations apply to secondary efflu-
ent, well seeded and where ammonia-nitrogen levels will vary from 10 to 22
mg/^ with an average of 16 rog/£.
NITRIFICATION AS AFFECTED BY pH AND ALKALINITY
The pH of the culture medium has been shown to affect the rate of growth
of both Hitrosomonas and Nitrobacter in pure and mixed cultures. It should
be remembered that Schoesing and Muntz (2) as previous noted on page 3, used
crushed calcium carbonate in order to neutralize the acids generated by
nitrifiers. These acids are actually the waste products of the organisms
involved and it is logical that they will become toxic at some finite con-
centration level. Alkaline substances' are therefore necessary to insure
that the acids will be neutralized and held at a low level in the vicinity
of the organisms.
Table 10 summarizes the reported values for optimal pH as noted in the
literature.
In the present research, observations of acid concentration soon re-
vealed the fact that acceptable pH conditions would prevail during nitrifi-
cation and that no adverse acid impact would be generated.
Inspection of Table 11 indicates that over a wide range of flow values,
no regular change in pH values was discernible in the recorded data. All
observations seemed to fit the optimum range for attached growth as defined
by Srna and Baggaley (21).
There was a drop in alkalinity apparent with increasing nitrification
but it lacked a well defined trend. Within a run the alkalinity dropped
from stage to stage but between runs observed changes were not uniform.
Since the Saline pilot unit flow was large and facilities were not
39
-------
TABLE 9. FINAL EXPERIMENTAL RESULTS
O
2
Plow gal/ ft /day* (to the point)
Stage Factor A-l
1 6.0 1.5
2 3.0 9-75
3 2.0 0.50
k 1.5 0.37
5 1.2 0.30
A-2 A-3 A-k A-5 A-6 A -7 A-fi
A-9 A-10 A-ll
3.0 6.0 9.0 12.0 15.0 18.0 2k, 0 30.0 36.0 21.0
1.5 3.0 U.5 6.0 7.5 9.0 12. o 15.0 18.0 10.5
1.0 2.0 3.0 k.O 5.0 6.0 8.
0.75 1.5 2.25 3.0 3.7 ^.5 6.
0.60 1.2 1.8 2.U 3.0 3.6 U.
5 1.0 0.25 0.50 1.0 1.5 2.0 2.5 3.0 k.
95*$ removal
90$ removal
85$ removal
D 10.0 12.0 7.0
0 7.5 9.0 5-2
3 6.0 7.2 k.2
0 5.0 6.0 3.5
*Multiply all terms by kO.7 to yield metric equivalents,
Tables A-l through A-ll will be found in Appendix A.
-------
TABLE 10. REPORTED OPTIMAL pH VALUES FOR NITRIFICATION
Authors
Organisms
Optimal
pH range
Date
H
Meyerhoff (21)
Hoffman & Lees (22)
Engel & Alexander (23)
Loveless & Painter (2k)
Buswell, et al. (25)
Lees (26)
Meyerhoff (21)
Boon & Laudelot (27)
Wild, Sawyer & McMahon (28)
Downing, et al. (29)
Huang & Hopson (JO)
Srna & Baggaley (2l)
Nitrosomonas - pure culture
Nitrosomonas - pure culture
Nitrosomonas - pure culture
ETitrosomonas - pure culture
Ritrosomonas - pure culture
Nitrobacter - pure culture
Nitrobacter - pure culture
Nitrobacter - pure culture
Mixed Culture - Activated Sludge
Mixed Culture - Activated Sludge
Mixed Culture - Attached Growth
Mixed Culture - Attached- Growth
8.5-8.8
8.0 - 9.0
7.2 - 9.0
7-5-8.0
8.0-8.5
7.2 -8.2
8.5-9.0
7.0-8.6
B.h
7.2 -8.0
8.5
7.0-8.2
1917
1955
i960
1968
195^
1917
1962
1971
1966
197^
1975
-------
TABLE 11. TYPICAL pH AND ALKALINITY VALUES DURING NITRIFICATION AT SALINE
ro
Flow load
£/m 2/day
10
Ui
163
203
142
Date
8/12/75 pH
12/31/75 PH
Alk*
8/25/76 pH
Alk
9/15/76 PH
Alk
12/31/76 pH
Alk
Sampling point
Sl
-
-
-
7.4
237
7.3
285
7.4
192
S2
7.4
7.7
142
7-4
232
7.3
280
7.1
184
S3
7.8
7.8
130
7.5
212
7.3
276
7.2
176
S4
7.9
7.9
130
7.4
202
7.2
266
7.1
152
s
8.0
8.2
12k
7.k
197
7.3
251*
7.2
140
S6
7.9
8.1
112
7.3
182
7.4
248
7.1
124
S7
8.1
8.0
93
7.3
177
7.2
232
7.2
Qh
-------
provided for systematic pH adjustment in the field, it was evident that any
work on the subject of pH would have to be carried out in the laboratory.
As a result, a six-stage laboratory unit, 2 ft (0.6l m) in diameter was
evaluated at eleven levels of alkalinity. The influent ammonia-nitrogen was
set at 20 mg/£ and analyses were run on the plant effluent. Figure 11 shows
the values of ammonia-nitrogen at each stage as well as the effect of nitri-
fication on the respective effluent levels of alkalinity. Figure 12 indi-
cates that the rate of usage of alkalinity closely approximates 7 mg/,0 per
mg/,0 of ammonia-nitrogen oxidized.
Figure 13 relates the coefficient of pH dependence (KpH) to the same
coefficient at pH 7-5 (K7.5)- The relationship suggests that nitrification
ceases at pH 6.0. This observation must be tempered by the concept of short-
term change as contrasted to long-term change. In the latter case, accli-
mation has taken place. The response of such a culture may appear to gen-
erate an exception to the pattern defined in Figure 13. In actuality, long-
term and short-term responses are two distinct responses to an environmental
condition. Both are a normal pattern of development in nitrification. Long-
term change is much more difficult to establish and in waste treatment, may
well require conditions that would be difficult to establish for a long
enough period to develop the necessary flora. Haug and McCarty (22) de-
veloped a nitrifying culture at pH 6.0 that functioned to produce complete
oxidation after 10 days in their submerged filter. This must be considered
a long-term response in contrast to the suggestion of zero nitrification
predicted by Figure 13 as a short-term response.
EFFECT OF TEMPERATURE ON NITRIFICATION
The optimum temperature for nitrification reported in the literature
varies considerably. Buswell (25) cites 30'°-36°C as optimum for Nitro-
somonas. Laudelot and Van Tichelen (23) report 42 °C as an optimum for Nitro-
b'acter while Painter (24) found that 3^-c-35°C was best for the same organism.
Little or no growth was experienced below 5°C and above 45 °C for both Nitro-
somonas and for Nitrobacter. Gibbs (35) reported that 53°-55°C inactivated
nitrifiers. Sawyer and Bradney (26) used pasteurization at 55°C for inacti-
vation of nitrifiers in BOD work which has proven to be very effective. The
Technology Transfer publication on Nitrogen Control (37) implies that at-
tached cultures can withstand cold temperatures considerably better than sus-
pended cultures. There is still some inconsistency in the literature regard-
ing temperature effects and it was hoped that this research would help clar-
ify the situation.
The field units at Saline were set up in a temporary frame building in
which a row of plywood windows could be opened for easy access in removing
-------
20
15
Flow Rate =1.2* 0.1 f/min
(3gpd/ft2)
o>
e
10
ro
I
Ul
_l
U.
u.
UJ
Influent Alk.
as CaC03)
38.0
43.5
56.5
59.5
71.0
80.0
100.0
116.0
129.0
136.0
151.0
o
a
o
v
X
m
Eff. Alk.
0.5
INF.
3
STAGE
Figure 11. Effect of alkalinity on nitrification.
-------
f-
vn
o»
£10
10
I
Z
LJ
UJ
Nitrification
dependent on
Alkalinity
Nitrification
^independent of
influent Alkalinity
I
0
50 100 ISO
INFLUENT ALKALINITY (mg/^ as CaC03)
200
Figure 12. Nffc-N oxidation as a function of alkalinity.
-------
Figure 13. fflj-W oxidation as a function of pH.
-------
the discs. The major source of heat for the entire operation was the warm
sewage flowing over the discs. When the windows were tightly closed the
interior temperature fell to a low of 9°C. It was thought that opening the
windows by degrees during the coldest winter months would slowly depress the
temperature and enable observations to be made below 9°C.
The 2-ft (0.6l m) unit held less heat and was placed somewhat lower in
the room than its if-ft (1.2 m) counterpart. It was frozen solid when-no ef-
fect was apparent on the if-ft (1.2 m) unit. As the ice formed and the discs
rotated, the biomass was neatly stripped from the disc surfaces. The 2-ft
(0.6l m) unit had to be abandoned.
Further work with the if-ft (1.2 m) unit showed the futility of the
total approach. The air temperature at one point outside was 12°C below
zero, directly over the if-ft (1.2 m) unit it was 2°C below zero and the
reactor fluid was 6° to 7°C. Thus the biomass was circulating in the air at
-2°C with gusts to -12°C and the environment in the liquid phase was at +7°C.
This condition was.not one in which good temperature work could be performed.
The date on which this occurred was,December 1, 19?6 and again on December 13
and lif. Table A-ll in Appendix A shows the effect on the nitrification pro-
cess. Effluent ammonia-K'increased from 0.8 mg/^ to 12.9 mg/£. The window
was closed the next day with an immediate improvement. The process did not
appear to be harmed by the contact with such cold air. Another similar ex-
perience on December 13 and lif, 1976 produced a similar result. Again it
appeared that a laboratory study would be the best approach to the problem.
The design of the laboratory equipment involved six stages of 2-ft (0.6l m)
reactors and a synthetic feed. Laboratory cooling equipment could be used to
moderate the temperatures in the liquid phase, but no controlled environ-
mental room was available to prevent some warming up of the six-stage reactor
(especially at 2°C level). As a result it was decided to proceed with a
gradient of temperature through the reactors. The responses obtained at the
different temperatures are shown in Figure lif. Figure 15 is an attempt to
normalize the data for a series of single temperature values rather than the
use of ranges. The result is a useful set of curves. Figure l6 is a locus
of points reflecting the ratio of the reaction coefficient at any temperature
T to the coefficient at 20°C, plotted against temperature. K is defined as
mg of ammonia-N removed per mg of biomass per hour. The resulting .values ap-
pear to define a steadily increasing rate of nitrification from 2°C to 30°C.
This relationship too must be characterized as a short-term response.
Probably the if-ft (1.2 m) reactor at Saline was more nearly performing
in a long-term response mode. As a result, data taken from it were not ex-
pected to correlate with the laboratory work. Results at Saline were divided
into sets covering temperatures (6-8)°C, (8-10)°C, (10-12)°C, and (l2-13)°C.
Reaction rates for similar temperature ranges as observed in the laboratory
work can be computed from Figure l6 and adjusted to 1.0 at 12.5°C. The
-------
20
15
o>
z
z
I-
2
UJ
ID
UJ
Flow Rate = 3 gpd/ft'
19.6~20.0-
24.1^26.9-
29.0^33.-
INF.
34
STAGE
Figure lU. Laboratory temperature study.
-------
20
-fr-
VO
D»
e
10
10
LL)
ID
_J
LL.
Li_
LU
Temperature, °C
5
INF.
3
STAGE
Figure 15. Normalized temperature data,
-------
2.0
kT/k20
1.0
o
10 20
TEMPERATURE, C
30
Figure l6. Temperature factor based on norm of 20 C,
-------
values obtained were (0.53), (0.62), (0.80), and (l.O). Thus is would be
predicted that removal percentages would decline by 50<$ with a temperature
decline from 12° to 6°C.
The data at Saline for the sets enumerated behaved in a much more uni-
form fashion. For example, the reaction rates noted for the sets defined
above were as follows: (0.773), (0.77*0, (0.771), and (l.O). On this basis
the unit showed slight temperature adjustment from 6°C to 10°C and only a
22% reduction in reaction rates for the entire interval. Apparently the
heavier attached film, at Saline appears to be more insensitive to temperature
changes than the thinner films of the laboratory reactors. The adaptation to
produce an acclimated slime at Saline might also account for the degree of
reduced sensitivity.
Figure 17 was obtained by the use of a series of bottles in a water
bath. The nitrifier culture was suspended in the bottles and supplied with
the standard artificial media (Appendix D). The results obtained compared to
Figure l6 are quite similar. Both Figures 16 and 17 must be considered
short-term responses.
Experience with the bio-film type of reactor seems to establish the
fact that the degree of acclimation is an important aspect in the response
of the disc system to lower temperatures. Certainly the use of short-term
response values would be on the safe side.
Actual temperature corrections will depend on several factors. First,
the biomass thickness is highly variable. Once a heavy slime mass is de-
veloped, it appears that because of diffusional difficulties the interior
layers are starved for substrate. The onset of cold weather will slow down
the use of substrate by the outer slime layers and this will then allow the
interior layers to function in further removals than would otherwise be
possible.
Laboratory die-away experiments would indicate that a maximum decline
in biomass of 1% per day at room temperature could take place. At the cold
weather temperatures of 10°C or below, die-away might be reduced to 0.5%
per day or less. Thus fairly respectable removals of ammonia should be pos-
sible for much of the cold weather, if a plant operator can enter the winter
period with a substantial layer of active slime on his disc system.
SPEED OF ROTATION, OXYGEN EFFECTS, AND SLIME BUILDUP
The original speed of rotation was selected after a short preliminary
run in the laboratory. Eesults seemed to indicate that at 10 rpm (for a 2-
ft (0.6l m) unit) sufficient oxygenation was produced for the laboratory
51
-------
vn
rv>
4
6
8 10 12 14
TEMPERATURE, °C
16
18
20
Figure 17. Temperature effects on nitrification rate.
-------
units to complete their oxidation reactions. The peripheral velocity at 10
rpm on the 2-ft (0.6l m) laboratory model was 63 ft/min (10 m/min).
Initially therefore, all work was carried out at peripheral speeds of
about 60 ft/min (10 m/min) while this value was given a further check. The
first check was carried out in the laboratory since the large field unit was
being kept busy with the collection of field data (Tables A-l through A-11
and B-l through B-10 in Appendices A and B).
Figure 18 shows the results of slowing the laboratory unit to 5 rpm
then to 2.5 rpm and then speeding it back up to 7.5 rpm.
The laboratory unit at 10 rpm was removing 19 mg/£ of a 20-mg/£
ammonia-nitrogen influent. This was equivalent to a 95$ removal and hence
was considered a typical performance. Decreasing the speed to 5 rpm pro-
duced an immediate decline in efficiency to 92.5$ removal. While 2.5$ was
not a large decline still the uniformity of the results was quite definite.
At 2.5 rpm the removal efficiency declined to 8k% showing a rather dra-
matic impairment in removal efficiency. The unit was operated at this rate
for a period of one week. At this point, believing that the culture might
be lost, the speed was raised to 7-5 rpm and the performance returned to its
former level rather immediately.
At this point, the question was raised as to whether a deficiency in
oxygen was the cause of the decline in efficiency. Examination of the liquid
phase of the system showed that such was noti the case. Dissolved oxygen
electrode measurements were made in the liquid phase regularly and always
seemed to be above k mg/£. The critical point for an oxygen deficiency
however would not be in the liquid phase but in the slime layer on the disc.
Unfortunately the slime layer on a moving disc was too involved a biological
system for an electrode measurement of D.O. at this particular time.
Several scrapings from the disc surfaces placed in BOD bottles and pro-
vided with substrate and oxygen were studied. Typical of these results taken
in the laboratory are the data shown in Figure 19. From this data the fol-
lowing observation seems pertinent (Table 12). While the uptake rates
seemed to be very constant with time, there was a tendency for a slight
break in the curve at a D.O. level of 0.5 ppm- This was interpreted to
mean that the oxidation rate begins to be impaired at a D.O. concentration
of 0.5 mg/ji for the biomass when suspended in the confines of a bottle. The
same effect was obtained using a nitrifying sludge from an activated sludge
process. In fact in numerous test of all types of nitrifying cultures, the
same characteristic was demonstrated. Since oxidation efficiency shows im-
pairment at oxygen levels well above this limit in the disc reactor vessels,
no conclusion can be projected from this type of observation for application
53
-------
o>
E.4
d
z
o
o
1=3
yj
31
u_
u.
UJ
0
Loading Rate: 2.5 gpd/ft2
No. of Stages: 6
Location: Laboratory
—o
00 o
o o o
-10 RPM
5 RPM
o
o o
*2.5 RPM-*
7.5 RPM
Dec. 25 Dec. 31 Jan. 3 Jan.11
DATE
Jan.17 Jan.22
Figure 18. Effects of rotating speed on nitrification (2-ft discs).
-------
6.0
10 20 30 40 50 60 70 80 90 100 120 130 140 150 160 170 180
TIME MIN.
Figure 19. Oxygen uptake of disc scrapings.
-------
to the disc system at least at this time.
TABLE 12. BIOMASS AW OXYGEN UPTAKE
Stage
1
2
3
4
D.O. uptake
mg/hr
15.0
13.6
4.7
1.8
-:Biomass
dry wt mg
1005
725
485
270
D.O. uptake
mg/mg biomass
0.015
0.018
0.0097
0.0067
Additional speed tests were carried on at Saline using the 2-ft (0.6l m)
diameter units. The biomass layers were heavier than the laboratory films
and the oxygen diffusion problems should have been more critical. Eight
stages were employed and at each speed about 24 hr was allowed for equilib-
rium to become established. The flow rate for this work was set at 5.0
gpd/ft2 (122 ,g/m2/day).
Figure 20 gives the observed values in terms of ammonia-nitrogen re-
moved for six different speeds and eight stages. In spite of the heavy
biomass, 10 rpm seemed to give adequate oxygenation. 15 and 20 rpm showed
little or no improvement while a drop to 7-5 rpm showed a loss in effienciey
of about yJ0.
Effluent dissolved oxygen decreased from 6.5 mg/,0 at 20 rpm to 2.5 mg/Jl
at 2.5 rpm. At 7-5 rpm the effluent D.O. was 4.5 mg/,g while at 10 rpm the
same parameter was 5.5 mg/,0. Figure 21 shows the effluent relationships
better than can be described verbally. However the D.O profiles through the
system (Figure 22) using an rpm of 10 as acceptable performance, would es-
tablish 3-5 mg/,0 as the critical concentration in the bulk fluid for accept-
able nitrification in the slime layer.
The 3.5 mg/£ concentration is the bulk concentration which was required
in this case for satisfactory performance of the first three stages at the
10-rpm level. These stages contain by far the greatest weight of biomass,
oxidize the largest part of the ammonia-nitrogen and'therefore require the
greatest amount of dissolved oxygen (see Table 13).
Visual examination indicated that the above biological films were as
heavy as any that had been worked with over the two-year period of the study.
Still the question of the nature of the film and its activity came up re-
peatedly. Visually again, it seemed that the biomass in the field unit when
compared with a well seeded laboratory unit:
56
-------
10O
vn
—J
o
345
STAGE NO.
100
8
Figure 20. Rotating speed versus nitrification at Saline.
-------
8.0
7.0
6.0
o>
§5.0
-------
INF.
Figure 22. Rotating speed versus D.O. by stages at Saline.
59
-------
TABLE 13. BODc OF SALINE PILOT PLANT SAMPLES
a\
o
Hydraulic
load,
til
61
81
101
163
203
Date
12/31/75
1/26/76
2/09/76
3/03/76
3/10/76
3/17/76
3/24/76
4/07/76
4/14/76
4/28/76
5/19/76
8/25/76
9/15/77
Sampling point
Sl
-
17
3
11
18
12
6
24
10
9
6
17
9
S2
17
17
2
8
13
10
4
17
6
7
5
11
4
S3
17
9
3
1
10
5
3
12
3
8
5
10
5
su
19
9
2
0
10
10
3
2
1
6
5
10
4
S5
7
11
1
0
9
9
3
4
l
8
6
9
7
S6
4
11
1
1
7
6
2
2
0
4
4
9
5
S7
2
7
1
0
4
3
2
0
1
4
4
8
U
-------
(l) became established more quickly on a new surface;
(2) reached maturity faster;
(3) was much heavier and thicker after maturation; and
(h) was less active on a unit mass basis.
It was assumed that biomass in the laboratory was much closer to a pure cul-
ture than the biomass in the field. In the Saline effluent (sample point l)
some BOD was always found tributary to the pilot unit. The amount as indi-
cated in Table 13 was quite small and it was not thought by itself to ac-
count for the differences in the slime coats observed between the laboratory
and the field units. Trace elements, suspended solids, and bacterial seed
were other environmental aspects that could have affected the buildup of the
biomass. In all probability all of these factors played some part in the
slime layer formation.
In essence the field biomass initially grows better because of more
ideal combinations of growth factors. Increased numbers of heterotrophs are
likely to be part of this slime buildup. These- organisms probably 'initially
exist in a symbiotic relationship which results in better adhesion of the
nitrifying seed organisms. Algal cells too are part of the complex slime
layer since they inhabit the open clarifiers of the treatment works. Thus
the slime growth represents an almost complete biological community in and
of itself.
Catabolic activities begin to assert themselves as the slime increases
in thickness. This is reflected in additional heterotrophic activity, in
effect these oxidative activities result in aerobic digestion of some ele-
ments of the slime. Oxygen usage is not simply for oxidation of ammonia.
The slime metabolic activity may only minimally reflect the nitrifier popu-
lation.
From these considerations it seems most probable that a useful auto-
trophic biomass determination by a scrape and weigh technique is not possi-
ble. Nevertheless, such values measured over a span of time gave some mea-
sure of the possible range of biomass concentrations. Two field studies
gave results as indicated in Figure 23. At the same time a laboratory unit
loaded at an intermediate flow loading and with ammonia-nitrogen at 20 mg/,0
was producing 95?o oxidation. The discs were practically without noticeable
growth. A finger held against the rotating surface revealved little or no
slime. Careful scraping of large areas would yield 1 mg/in. (1-5 g/m ) with
errors of ± 30%. When field units yield weights of biomass 10 to 100 times
this weight and yet give similar levels of nitrification, it seems apparent
that a large part of the field biomass must be made up of heterotrophs.
Table ih adds yet another perspective to the problem. This is, in
61
-------
3000
^2000
en
en
<
5
O
m
g 1000
60
D>
"50
in
x
w*
•<40
tn
en
<30
O
m
10
.5gpd/ft2 (1/5/77)
2.5gpd/ft2 (3/28/77)
0 0123456
STAGE
Figure 23. Typical biomass measurements.
62
-------
TABLE Ik. SCRAPE AND WEIGH 'STUDY OF SALINE BIOMASS
U)
Stage
1
2
3
k
5
6
Area of
biomass,
in.2
25
36
36
50
25
100
Wt. of
biomass,
mg
11+2
19U-
13^.1
215-^
5^.7
181.8
Wt . per
stage,
g
2?6
261
180
208
106
88
Z = 1119
02 uptake
w/o NHj, with NHj,
mg/hr mg hr
6.5 3^
8.0 1+3
6.1+ 1+3
7.2 1+9
3.0 8.7
5.0 25.8
02 diff.,
mg/hr
27.5
35-0
36.6
Ul.8
5-7
20.8
Max. 02 use
per stage,*
g/hr
53-5
1+7.2
^9-3
U0.5
11.1
10.1
Z = 211.7
*These values are based on a suspended sample and hence eliminate to a large extent diffusional
problems.
-------
a more complete study, typical of several that were carried out.
In this case the slime was generated using an intermediate flow loading of
2.5 gpd/ft2 (101 ^/m2/day) on a six-stage unit. Since the slime was quite
heavy in the initial stages and more sparse in the later stages, the area of
disc selected for scraping was based on what was judged visually as being
needed to give a reproducible sample. The areas chosen are shown in column
2 of Table Ik. The wet slime from the respective areas was caught and car-
ried back to the laboratory where it was processed. Representative portions
were dried to a constant weight of 103°C. Other portions were suspended in
bottles and the oxygen uptake rates were determined by D.O. electrodes.
Typically the solids so suspended were checked for D.O. uptake without
WHj-N present. This gave a measure of the endogenous activity. Then
ammonia-nitrogen was introduced and the D.O. uptake was recorded as being
the. total of all activities. However, the difference of these two values
was a fairly good estimate of the oxygen requirements of the total nitrifier
population of the slime layer when metabolizing ammonia-nitrogen.
At that point a comparison was made between the oxygen uptake of the
dispersed culture and the computed amount of oxygen required by the culture
in metabolizing the ammonia-nitrogen actually oxidized by the same biomass
when on the disc. For example, Table A-6 shows that on the average, of 12.2
iag/£ of NHj-N, all but 0.5 mg/£ of NHj-N was oxidized after passing six
stages when' the flow loading was 101 ,£/m2/day. Thus in one day the k-ft
(1.22 m) pilot unit oxidized 0.^93 lb (22k g) of ammonia-nitrogen. The
computations are shown below:
Actual oxygen needed to oxidize nitrogen removed would be:
Total area: 202J ft2
Total flow per day = 202J x 2.5 = 5058 gal
Weight of NHj-N:
5058 gal x 8.33 Ib/gal x 11.7 gm/,0 x k^k g/lb = 22k g N/day
Weight of necessary oxygen:
22k g W/day x 4.57 g 02/g N = 102J g 02/day
Reference to Table ~Lk shows the dry weight of biomass per stage and the oxy-
gen which could be used by each stage for purposes of oxidizing ammonia-
nitrogen if all nitrifiers in the slime were in a suspended-type culture.
In essence the summation of all six- stages is 211.7 g 02/hr (this figure has
been corrected for endogenous respiration).
211.7 g 02/hr x 2k hr/day = 5080 g 02/day
6k
-------
The above computation shows that on the average, about 20% of the total
number of nitrifiers in the biomass layers are participating in the actual
oxidation going forward on the discs. Or, perhaps many of the nitrifiers
present are working at some reduced level of their actual potential depend-
ing on their depth in the biological film and the resulting diffusional prob-
lems in their metabolism. This latter possibility seems to be the most prob-
able mechanism.
The inference seems clear, that the nitrifiers are continually being
buried by the more rapidly growing heterotrophic biomass and this creates
diffusional problems, which in turn, prevents the full utilization of the
entire biomass layer under steady.state conditions. However, it seems amply
clear also, that many of these buried1 organisms can be reactivated under
proper conditions and thus constitute a reserve of organisms.
Table lU indicates that the weight of biomass remains high during the
first four stages and that the number of viable autotrophs also remains
high through these same four stages. However reference to Table A-6 indi-
cates that little ammonia-nitrogen is left to be oxidized by the discs at
stage h and that the driving force is likewise low. These-organisms must
therefore be supported by an occasional peak or slug of ammonia-nitrogen in
the form of an anomaly as previously noted. Such reserve organisms consti-
tute a safety factor which can be valuable to the system in time of stress.
SHOCK LOADS
Close examination of the data recorded in Tables A-l through A-ll,
Appendix A, indicates that when conditioned for a given substrate loading
and removal, the disc tends to extract substrate at that level. If a higher
loading becomes tributary to the system, the unit will extract some small
portion of the increase but pass the remainder to the effluent. Reference
to the latter portion of Table A-3 (Appendix A) illustrates this point. The
appropriate place in Table A-3 is indicated by the critical dates of sam-
pling (12/29 through 2/6).
Note that for an initial period of over two weeks in this designated
time interval, the disc system operated with a substrate concentration be-
tween 13.1+ and 16.0 mg/,g. The effluent was constantly at 0.1 mg/£. On
1/21 the influent jumped from 15 to l6.U mg/,0. The effluent responded by
increasing from 0.1 to 0.5 mg/^; on 1/23 the influent increased to l8 mg/J
and the effluent to 1.0 mg/,0; on 1/26 the influent increased to 22.2 mg/^
and the effluent to l.k mg/Jl. This interval of higher loadings constituted
about a week which was sufficient for acclimation to a somewhat higher sub-
strate concentration and thus further loadings at increased levels resulted
in higher removals as typified by the results on 2/l| and 2/6.
65
-------
It should be noted that the samples recorded in Table A-3 were 2U-hr
composits and hence constituted long-term (2k-hr) impacts on the system.
There are many such examples of this type of response throughout Tables A-l
through A-ll (Appendix A). The reader can extract other examples if he
chooses. Two points however should probably be emphasized here. First it
seems equally likely that in operation, the substrate strength will drop
about as often as it will rise. Obviously,, the disc system will respond well
to a drop in concentration.
Secondly., for most changing patterns involving modest long-term in-
creases, about one week of acclimation will provide the necessary increase
in biomass to adequately handle the increase in substrate.
Table A-3 reflects a flow loading which is essentially doubled to pro-
duce Table A-5. Appropriate acclimation time was allowed and the results in
Table A-5 show that the disc system responds well to a doubling of flow in
this range and with acclimation.
The question which arises is, since the 2U-hr shock constitutes a long-
term shock, would some shorter time become a short-term (more easily ab-
sorbed) shock.
The first shock study was set up in the laboratory. The study con-
sisted of 1-, 2-, and k-hr hydraulic flow shocks during which time the flow
was doubled for the designated period of time. This change simply raised
the flow from 1.25 gal/ft2/day (51 f/m2/day) to 2.5 gal/ft2/day (102
,£/m2/day). It should be noted that the higher flow is the value used in
Table A-6 of Appendix A and represents a flow loading which the disc can
easily be acclimated to accept with about one week of adverse results. After
this period of acclimation the system will provide about 95% removal of
ammonia-nitrogen. In this case however no time would be available for ac-
climation and this series of tests should give a measure of short-term re-
sponse to such a shock.
Figure 2k shows the continuous response in the six-stage laboratory
disc effluent when the 1-, 2-, and U-hr hydraulic shocks are applied. Fig-
ures A-9, A-10, and A-ll (Appendix A) give the intermediate, stage by stage,
values. Table 15 shows the total removal of the shock load added and the
maximum discharge concentrations of ammonia-nitrogen under each of the shock
load conditions.
Reference to Table 15 shows that during the 1-hr shock an additional
0.6 g of ammonia-nitrogen was added to the disc system and that 87% of that
shock was oxidized. This would constitute little or no impairment of efflu-
ent as revealed by a 2k-hr composite. The 2-hr flow shock and the k--hr flow
shock are both rather serious in their effect on the efficiency. These time
66
-------
ON
Duration
Influent NH3~N
Normal Flow 500ml/min
(1.25gpd/ft2)
Shock Flow 1000ml/min
(2.5gpd/ft2)
1 Hr Shock
2Hr Shock
a 4Hr Shock
3456
TIME(HR.)
Figure 2k. Flow shock effects.
8
-------
periods are therefore serious enough to be considered long term and hence
to require some acclimation.
Hydraulic
application
rate,
i/m 2/day
102
102
102
TABLE 15.
Shock
duration,
hr
1
2
h
FLOW SHOCK
Total
NBj-N
added,
g
0.6
1.2
2.4
EVALUATION
Percent of
NHj-N
shock
removed
87.2
^3-9
27.1
Maximum
NH^-N
discharge
cone.
mg/,0
1.7
6.0
8.1
A concentration shock was handled in the same fashion as the flow shock.
Figure 25 shows the overall response while the nests of curves for inter-
mediate values are located in Appendix A (Figures A-12, A-13, and A-lU).
Table 16 indicates that concentration shocks are not as serious as flow
shocks. Since all other factors have been constant except driving force,
this latter factor must be important in shock load accommodation.
TABLE 16. CONCENTRATION SHOCK EVALUATION
Hydraulic
application
rate.
, p
£/m /day
51
51
51
Shock
duration,
hr
1
2
k
Total
NH^-N
added .
g
0.6
1.2
2.4
Percent of
NH^-N
shock
removed
70.7
67.1
82.1
Maximum
NH^-N
discharge
cone .
1.2
5.0
5-0
Further analysis of these data is carried out in Tables 17 and 18.
The results indicate that the distribution of biomass, as revealed by the
nitrogen removal data, is not always regular. This fact has been pointed
out previously. Assuming that biomass and nitrogen oxidation are propor-
tional, four of the six tests made in this case have biomass which is a
maximum on stage 1 and tapers down to a low value on stage,'6. These would
be the 1- and 2-hr flow shock tests and the 1- and k-hr concentration shock
tests. The two reamining series have peak biomass on stage 3. It should be
-------
ON
VQ
10 -
6—
tr
S
u
2
O
O
o
UJ
Duration of Strength Shock
0
Flow 500 ml/min .
(1.25gpd/ft2)
Normal Strength of Influent
20mgA? NH3-N
Shock Strength of Influent
40mg/| NH3-N
o 1 Hr Shock
A 2 Hr Shock
a 4 Hr Shock
23456
TIME (HR)
Figure 25. Strength shock effects.
8
-------
—5
O
s s
TABLE 17. FLOW SHOCK DATA
Stage
1
2
3
1*
5
6
1-hr
R *
ss
0.9^5
0.810
0.783
0.095
0.027
0
shock
R *
sl
0.053
0.363
0.097
0.0148
0.037
2-hr
R
ss
1.13^
0.81+6
l.ljU
o.iM
0.072
0.018
shock
R
si
— -.
0.155
0.38^
0.156
0.075
0.014-8
k-hr
R
ss
0.918
1.505
2.066
0.357
0.128
0.051
shock
R
si
--
--
0.063
0.3^2
O.l6l
0.168
removal at steady state prior to shock.
R = removal of shock load (g).
S JL
TABLE 18. CONCENTRATION SHOCK DATA
Stage
1
2
3
1+
5
6
1-hr
R
ss
0.9^5
0.878
0.797
0.122
o.oi+o
0.013
shock
Rsl
_ _
0.11*8
0.217
0.025
0.032
0.025
2-hr
R
ss
1.283
1.682
1.995
0.228
o.nU
0.029
shock
Rsl
0.095
--
0.390
0.2kb
0.157
0.0^7
U-hr
R
ss
1.733
1.238
1.058
0, 113
0.0^-5
0.0*4-5
shock
Rsl
— —
0.109
1.209
0.212
o.ioU
0.10k
-------
noted then, that all these tests were made on a series of six stages which
were fed at a constant flow of 1.25 gpd/ft2 (51 J/m2/day) and at 20 mg/J
of ammonia-nitrogen during their steady state development. In other words
they should have had similar biomass developments but obviously were widely
different.
Based on the steady state oxidation levels achieved before the shock
loads were initiated, Tables 17 and 18 give the entire series of R,,,, values.
o Jb
(Rss is defined as the steady state removal of ammonia-nitrogen achieved by
that stage prior to the appropriate shock load. RS]_ is defined as the re-
moval of ammonia-nitrogen by the appropriate stage during the shock load.)
Examination of the Rgs terms for all stage 1 shock studies reveals that even
when they are not the highest in the series, they are usually quite substan-
tial. It would therefore be expected that whatever removal of the shock load
does take plase, at least a part of it would be accomplished by the biomass
on stage 1. In five of the six shock load studies no increment of the shock
load is affected to any extent on stage 1. In all cases but one the peak is
taken at stage 3 whether or not that point is the peak of biomass in the sys-
ten. As a result of these consideration, while biomass must be considered
important in the accommodation of a shock load, it is obviously not the major
factor involved. The research to this point would tend to emphasize previous
history of development, activity of the biomass, and diffusional problems as
important factors as well as driving force and detention time.
Whatever the important factors involved in the accommodation of a shock
load, it seems apparent that stages 1 and 2 are totally ineffective in this
activity for any shock load of consequence. This emphasizes again the value
of more stages rather than fewer stages where such an alternative is possible.
Table 15 indicates that 87.2% of the shock load tributary to the disc
system during a 1-hr flow shock is removed. The regularity of the trend in
removal percentages suggests that less than 1-hr shocks can easily be accom-
modated while shock flows of less than 100$ additional flow can probably be
adsorbed for proportionally longer periods of time.
It should be emphasized that concentration shocks appear to be accom-
modated in a better fashion than flow shocks for the same weight of ammonia-
nitrogen substrate. This fact implies that time is important as well as
driving force when acclimation is not provided (as when a short-time shock
load occurs).
If a rational approach is taken in the analysis of the response to a
shock load the following question might be asked as a first step:
"Is the autotrophic biomass basically a major
factor in the removal experienced?"
71
-------
The k-hr shock concentration test removed the largest mass of the shock
fed. As a result it would probably be the best condition to analyze. Table
16 shows 2.28 g applied and 1.90 g removed. Further, the distribution of
biomass would show the following percentages:
TABLE 19. DISTRIBUTION OF BIOMASS AND SHOCK REMOVAL
Stage
1
2
3
h
5
6
Percentage
of total
biomass
Uo.8
29.3
25.0
2.7
1.1
1.1
Z = 100.0
Percentage
of shock
removed
0.0
5-7
63.6
11.1
lU.l
5-5
Z = 100.0
Ratio of
column 3/
column 2
0.0
0.2
2.5
k.l
12.8
5.0
This computation shows that while stage 1 has q-0% of the total biomass,
it removed none of the shock load. Stage 2 with 29% of the total biomass
removes only 6% of the shock load. But stage 3 with 25$ of the biomass re-
moves 63% of the shock load. Stages U, 5, and 6 remove lesser percentages.
However if the amount removed is compared to the biomass on that stage some
outstanding performances are noted. For example only L% of the total biomass
existed on stage 5 and yet it removed lk% of the shock load applied. If
stage 1 had performed in similar fashion, most of the shock load in question
would have been removed at that point. It must be concluded that, in answer
to the question posed, biomass and specifically autotrophic biomass does not
alone account for shock load removals.
Reference to Figure A-lU (Appendix A) shows the profile of the ammonia-
nitrogen species by stage for the U-hr concentration shock loading. Stage 1
had an average steady state influent ammonia-nitrogen of 12 mg/i and an ef-
fluent of 7-5 mg/^. With a low growth rate and an excess ammonia of 7.5
mg/f, a sudden increase in that nutrient element for a short period of time
could probably not affect the stage I biomass. Stage 2 had an influent of
7.5 mg/,0 and an effluent of k mg/g. Again the effect of additional ammonia
would be minimal. However by the time stage 3 is reached, the biomass under
steady state, has been somewhat starved. There is still substantial biomass
on stage 3 and hence resistance to diffusion, but the steady state concen-
tration in the reactor was only about 1 mg/J. This was probably too low a
concentration to nourish the film at an acceptable rate. Hence, when a slug
72
-------
of nutrient such as was applied during the b-br shock load became available,
it was quickly metabolized. Unfortunately as the degree of starvation in-
creases throughout the remaining stages, the autotrophic biomass is decreas-
ing. As a result the capacity of the system to counteract a shock load be-
yond stage 3 is not substantial.
A word or two here about driving force seems in order. It is possible
in a concentration shock load situation to have only a fraction of the bio-
mass fully active as illustrated in Table ll+. Thus the biomass is available,
the substrate becomes available (from the shock load) as well as the driving
force for that substrate. Then the problem may be, that the oxygen concen-
tration in the bulk fluid is not sufficiently high to provide an adequate
driving force for that component. In other words, the term driving force
covers more than a single ingredient.
At this point it might be appropriate to review the points of interest
bearing on the questions of mechanism, biomass, sloughing, and shock load
potential. All of these functions appear to be interrelated. The study to
date seems to indicate that the following theory may be proposed:
(l) The autotrophs which carry on nitrification appear to be
capable of remaining viable under conditions where little or no
substrate is available to them for protracted period of time. The
die-off rate in effect is very low. In one case where a culture
of 370 mg/,0 was aerated without substrate over a period of two
weeks, the loss of biomass amounted to 0.01 g/g/day.
(2) Such starved organisms age or decline slowly in their
ability to metabolize their normal substrate. This probably is
best described as a form of reduced activity. A culture of or-
ganisms of low activity can be restored to high activity with
about three days of intensive feeding in an environment of excess
oxygen and other required nutrients.
(3) As a result of the above, with each level of biomass
must be associated an activity factor which reflects the ability
of that biomass to metabolize its substrate expressed as mg of
Mb-N/mg of biomass/hr.
In the bio-disc system, each stage in a series of stages
has a typical biomass. Each stage in turn has to be cultured at a
lower and lower level of substrate reflecting the removal of
those stages lying above it in the series. Thus each stage in a
series operation might be expected to have a lower activity fac-
tor than the previous stage.
73
-------
Figure 19 and Table 12, show the relative oxygen uptake
rates by stage for the first four stages in a series. These values
reflect approximately, the rate of ammonia-nitrogen oxidation or
activity of the autotrophs because the responses shown were cor-
rected for endogenous respiration. It should be noted that results
in Table 12 were obtained under conditions where the entire thick-
ness of biomass was scraped from the discs, dispersed in a bottle
of oxygenated substrate, and the oxygen decline monitored by elec-
trode. The straight-line portions of Figure 19 thus reflect a con-
dition where both food and oxygen were in excess and where diffu-
sion into the film has virtually been eliminated.
(5) If the biological growth in (h) above had been anchored
in place on a series of discs, the decline in activity would still
be present but would in addition reflect the effects of diffusion
into the film, decline of substrate with staging, and most criti-
cal of all, oxygen limitation in the early stages. If one exam-
ines the results for stages 1 and 2, in the data reflecting the
rpm studies, specifically Figure 20, it is apparent that, all else
being constant, as the rotational speed goes up for a given stage,
the ammonia-nitrogen removal efficiency does improve. This rein-
forces the belief that oxygen limitation exists.
It appears that the same can be said for all stages ex-
cept for the fact that the substrate concentration is declining
at the same time. It actually reaches such low levels in the
latter stages that the reaction is substrate limited as suggested by
Figure 28. Because of the lower demand for oxygen this element
actually increases in the bulk fluid of the latter stages as in-
dicated by Figure 22.
(6) It appears that at a fixed rpm level, little lattitude
exists in the oxygen resources. Hence, the substrate to be oxi-
dized on a given stage can only be increased up to a fixed level
suggested by Figure 9 as (3 g/m^/day). At that substrate level,
that stage becomes oxygen limited. No matter what level of ammonia-
nitrogen either as substrate or driving force is applied to what-
ever level of biomass exists at that point, none of the additional
substrate can be utilized. This then would be true as long as the
oxygen limitation persists. Of course such a situation causes
the excess ammonia-nitrogen to pass on down the series of discs
providing food for the next stage (when such exists).
(7) An oxygen limitation in the autotrophic community does
not stop growth of heterotrophs since they compete more favorably
for oxygen than do the nitrifiers.
-------
(8) As the heterotrophs continue to grow beyond the limit of
growth for the autotrophs, a continual burial of the autotrophs
takes place. This is due to the slime mass generated by the hetero-
trophs and would apply to all stages. However, it is most notice-
able in the first few stages, say 1 through k, which get most of the
available BOD tributary to the system.
(9) As the autotrophs become buried., diffusion makes it diff-
cult for them to keep metabolizing the same level of substrate de-
fined by Figure 9 (0.3 g/m2/day). Therefore, a reduction in their
activity takes place producing a concurrent rise in ammonia-nitrogen
in the bulk fluid (previously defined as an anomaly). This rise in
substrate level proceeds to the next stage generating a pulse of
food and sustenance for the previously unfed autotrophs on further
stages down the series.
(10) In the meanwhile new autotrophs beging to form a new layer
of more active nitrifiers above the original and now buried layer of
autotrophs. These can now grow since reduced activity has relieved
the previous oxygen limitations to some extent. As a result of the
above, layer upon layer of biomass is built up. The deeper layers
are older and less active but each metabolizes its aliquot of avail-
able substrate. Each is limited only by the amount of biomass in
the layer, its unique activity factor and the diffusional problems
each has with oxygen and substrate.
(ll) It seems clear that there are many layers of organisms
living on reduced levels of substrate. This fact must be stressed
since all bio-films which have been examined have large numbers of
nitrifiers which are not being fully utilized. Table lk and the
associated computation show an average of 2
-------
3 and k, show that any shock load is taken by the latter stages.
These lie in a region defined by relatively high biomass, accept-
able oxygen concentrations and at least intermittent starvation.
TABLE 20. FURTHER ANALYSIS OF TABLE ih
System component
ffib-N cone, driving
force (mg/^)
NHz-N oxidized (mg/^)
1
7.0
5-2
2
3-9
3-1
Stage
3 k
1.7 1-3
2.2 O.k
5
0.7
0.6
6
0.5
0.5
Og required by WPfe-W
(g/day) ^ 271 192 35 52 17
02 used by same slime
when dispersed (g/day) 128*1 1133 1183 972 266 2 1+2
Ratio line 3 / line U 0.35 0.2k 0.16 Q.Ok 0.20 0.07
Total biomass (g) 276 26l l80 208 106 88
(12) It seems clear that the disc system has extra organisms
in the depth of the bio-film on each stage as well as on successive
stages down the series. These two separate resources appear to be
safety factors and yet to serve different purposes. For example,
a typical response might show (Table 19) 0.0$ of shock load taken
by stages 1 and 2 while stages 3 and 1+ take a very large percentage
of that same shock. The starved lower layers of stages 1 and 2
happened to be oxygen limited and unable to perform since these
stages were fully loaded. Hence, the shock load had to move down
the series to regions with unlimited oxygen. The value of unfed
or starved biomass farther down the series of stages thus seems
well defined. But, what is the value of the unfed or starved bio-
mass in the depths of stages 1 and 2? In essence these: lower
layers of starved nitrifiers provide the source of the seed orga-
isms and the origin of the new layers that are continually being
formed as observed in point (10) above.
This resource is quite beneficial. Once during the two
years of study covered by this project, a toxic contaminant de-
stroyed large masses of biological film. The biomass on stages 1
76
-------
and 2 of the pilot unit dropped by 50f0. The performance of these
stages declined markedly. The steady state load was taken up by
stages 3, k, and 5 and the reseeding of stages 1 and 2 was accom-
plished by the starved lower levels of organisms on those stages.
What was remarkable was that merely a ripple was noticed in the
overall performance. Further, stages 1 and 2 returned to full ac-
tivity within three days.
The above 12 points describe how the response of the disc system is
generated and how the biological forces combine with the mechanical forces to
become self-regulating mechanisms to distribute the substrate load.
From all the available facts, it seemed logical that under conditions
where each stage was fully loaded at about 3 g/m2/day of ammonia-nitrogen,
the unit should develop its maximum biomass on all stages. Theory would say
that even with high levels of autotrophs on all stages and 3.5 mg/^ of dis-
solved oxygen everywhere, no shock load would be picked up on any stage be-
cause no starvation would exist on any stage.
To check this assertion an eight-stage unit was set up at Saline with a
flow of 3 gpd/ft (122 0/m /day). Such a unit should be throught of as'being
flow loaded at 2k gpd/ft2 (978 ^/m2/day) on the first stage and hence k
gpd/ft (l63 ^/m /day) on six stages. It should be noted on Figure 8 that
such a unit is fully loaded. This is revealed by the virtual lack of curva-
ture in a typical flow loading curve.
Figure 26 shows the results obtained on a per stage basis when the unit
was given a k-hr concentration shock. The integrated areas under the curves
reveal that in this case, none of the shock load was touched by the pilot
unit. The curves are impressive since the influent concentration at Saline
was relatively stable over the period required for the test (7 hr). This was
normally not the case which would have tended to distort this type of data if
it had happened. At any rate, the theory proposed above seems fully validated
by such test results.
FLOW REVERSAL
In activated sludge work or other biological research, the effect of
shock loads is often very detrimental to the activity of the culture. Ni-
trifying cultures are far less prone to show the impact of such shock condi-
tions. In fact the feeling may be generated after working with such auto-
trophs that they act more like organic catalysts than biological cultures.
To cite a few example of this type of response which have been pre-
viously indicated in these data but which were perhaps overlooked by the
77
-------
—;
OD
1 23456
TIME (HR)
Figure 26. Profiles of h-hr shock load at Saline.
-------
casual reader. Note the following:
(1) Reference to Figures A-6 through A-ll covering shock loads
indicates that when the flow or strength was returned to its origi-
nal steady state condition after a shock, the ammonia removal re-
turned to its original level in all six cases. Reflection on this
fact indicates that even when the flow or strength was raised for up
to 7 hr, apparently the culture remained unchanged and thus could
give the exact response 7 hr later, which was exhibited originally.
(2) With"lowering of rotating speed and the resulting oxygen
depression, even' though this effect took place over a 7-day pe-
riod, the discs resumed their normal level of metabolism very
quickly when speed was resumed (the worst case took about 2k hr to
recover).
(5) The response to temperature was very similar. In essence
the recovery from a very adverse temperature was almost instanta-
neous, when a change to a more normal temperature was applied.
In essence it has been established that while nitrification biomass
grows very slowly, it dies away much more slowly. On this basis, if biomass
can be induced to grow by intermittent feeding, it might be possible to grow
a great deal of additional biomass on the last few stages of a series. It is
in this portion of a disc system that a deficiency of biomass may exist in a
moderately loaded system.
Head loss through an RBS system is also usually low and there is no rea-
son why the direction of flow should not be altered at will. If the direc-
tion of flow is reversed each day, wouldn't the last two stages or those
which have low biomass begin to experience biomass build-up to the same level
as the original first two stages? This should produce a more uniform dis-
tribution of biomass across the various stages of the unit.
In which case, for any given direction of flow, the last few stages will
have a high but partially starved level of biomass. This meets one of the
pre-conditions which was theorized as being necessary for coping with a shock
load.
Overall distribution of substrate and oxygen limitations would also have
to be considered. These latter conditions have to be controlled by devices
which are yet to be developed. In this case oxygen might be adjusted by speed
control of the discs or recirculating pumps involving aeration devices, etc.
Substrate might be controlled by D.O. electrodes combined with ammonia-
nitrogen electrodes.
79
-------
This last portion of the considerations would have to be considered re-
search beyond the scope of this effort. However, the portion on flow rever-
sal seemed well worth attempting. This phase of the work was tried first in
the laboratory. The six stages were activated normally then the flow was re-
versed. The removal by stage had been a curvilinear relationship for the
most part paralleling the biomass distribution. After one month of contin-
ually reversing flow every 2.h hr the biomass and the ammonia removal trend
had not changed. In essence when the flow was reversed, the removals re-
mained fixed in the same pattern as defined before reversal took place. It
seemed possible that the problem of seeding was at fault. A unit was there-
fore set up at Saline for the study of flow reversal. After 7 days of rever-
sal the ammonia removal profile was the same in each direction. Color, bio-
mass density and all other criteria indicated that the biomass was uniformly
distributed -throughout the unit.
Table 21 shows the development of this biomass which was equally effec-
tive in both directions and which required a little over one week for its
total development.
Obviously, in this mode, the last few stages in either direction have a
lot more biomass and are certainly starved for substrate. It would appear
that additional work will be necessary to validate the overall beneficial
characteristics of flow reversal.
SIMPLIFIED KINETICS APPLIED TO RBS NITRIFICATION
Development of a complete mathematical model describing the bio-disc
even if restricted to the aspect of nitrification appears to be a remote
possibility at this juncture. The ingredients involved in the nurture of
the biological culture are difficult to handle quantitatively.
First the biomass is extremely variable. The admixtures with hetero-
trophs appears to be almost infinite. As the heterotrophs increase in num-
bers, the resistance to diffusion likewise increases. The autotrophs respond
by growing at lower and lower rates. Thus a well developed bio-film repre-
sents an almost infinite spectrum of biological growth rates and diffusivity
problems.
The following technique is presented because it appears to be confirmed
by the assembled data. Several models involving inhibition, etc., have been
tried and found to be inapplicable. The following basic assumptions in this
simplified technique apply:
(a) Complete mixing occurs in each stage. (Tracer Study, see
Figure D-k.)
80
-------
TABLE 21. RESPONSE OF PILOT UNIT TO INITIATION OF FLOW REVERSAL
Date, Direction
1977 of flow
5/14 -*
5/18 -«-
OO
5/20 -*.
5/22 -*-
5/24 -*
xni j-uent;
27 .0* 27 .
11.
32.5 30.
1.
21.0 15.
Stage
2
3
5
0
2
2
27.4
12.J
27.0
1.1
11.8
3
27.7
13.*
24.0
1.2
6.2
4
27.1
14.3
22.4
1.7
3-1
5
27.
15-
19.
2.
2.
1
2
5
7
0
6
26.9
16.1
17-3
5-7
1.3
7
26.8
16.8
15.0
9-1
1.0
8
26.3
17.8
12.7
12.7
0.8
Influent
18.7
18.3
*A11 figures represent NIfe-N in mg/
-------
(b) All necessary nutrients are present in excess (with a staged
approach to treatment and D.O. above 3.5 mg/^j, this is basi-
ically true).
(c) Monod equation for growth rate is applicable:
C
^ ~ ^max Kg + C
where \i = specific growth rate, 1/hr
u = maximum specific growth rate. 1/hr
max ' '
K = half saturation coefficient, mg/,0
S
C = substrate concentration, mg/,0
p
X = biomass concentration, mg/m
(d) There is no significant loss of substrate within the system
(no sink)
(e) The presence of organic carbon and heterotrophic growth doe?
not interfere with nitrification.
The substrate balance then can be expressed as:
V • ^ = QC - QC - A -~Z x
dt o • Y K0 + C
o
where V = volume of a stage, &
Q = flow rate, n/hr
C = limiting substrate concentration, mg/J
Q
A = surface area per stage, m /stage
Y = yield coefficient, mg cells/mg substrate
The above equation can be rearranged to yield:
c) -(£ • ^-rH x c
dt V x o ' V V Y / K_ + C
O
82
-------
- O - K
dt V v o ' 1 K + C
A max
Assuming K = - • —— X
This assumption is based on an inability to determine appropriate values for
M-max> Y, and X. The analogy is applied as follows to ammonia^ nitrite and
nitrate nitrogen (organic nitrogen is omitted as unimportant).
MATERIAL BALANCE RELATIONSHIPS
First'Stage
dt
dC
1 ) + K - B /(K
dt V v o ly 2 1' v sb 1'
Second Stage
dA,,
dt
dB
V
V
Third Stage
dA,
dB,
V(Kss+V -
83
dt V v 2 T 1 ^
-------
Fourth Stage
IT = ?% - V + Kl • V(Kss + V - K2 ' V(Ksb + V
dcu
Fifth Stage
^ = - (B, - B ) + K • A / (K + Aj - K0 • Bc / (K + Bc)
dt V U 5 1 5' v ss y 2 5' sb 5
dC5 0
si — -2i /p p "\ J. y • -D / (v 4- Tl \
dt ~ V (S " 5J 2 B-5/ (Ksb B5}
Sixth Stage
dA,
= S (A _ A ) _ K • A /(K +
^ 7 v
— VJT. — n. , / — J.Y n-x/ViV ' -"•/' /
dt v v 5 6 l 67 v ss 6'
dB6 0
IT = V (B5 - B6} + Kl ' A6/^Kss + V - K2 ' B6/(Ksb
^ = S(c _C)+K . B /(K +B)
dt V 5 6 2 6 sb 6
where A. = ammonia concentration at ith stage, mg/,g
B. = nitrite concentration at ith stage, mg/,0
C. = nitrate concentration at ith stage,
-------
Kgs - half-saturation coefficient for Nitrosomonas, mg/£
Kgb = half-saturation coefficient for Nitrobacter, mg/£
K = rate coefficient for ammonia oxidation, mg/,g • hr
K = rate coefficient for nitrite oxidation,, mg/j • hr
The above equations were solved numerically by the use of the Continuous Sys-
tem Modeling Program, available in the IBM library package.
The results were calculated for the series of flow loading values used
and recorded in Appendix A (Tables A-l through A-ll). The kinetic factors
are shown in Table 22 below.
TABLE 22. CALCULATED KINETIC COEFFICIENTS FROM SALINE PILOT F
Flow
loading.
gpd/ft2
0.25
1.00
2.00
2.50
3-00
If-. 00
6.00
Detention time
per
min
156.6
39-0
19-5
15.6
12.9
9-7
6.5
stage
hr
2.666
0.660
0.330
0.260
0.216
0.163
0.108
Units
mg/£ • hr
12
30
U5
60
60
60
60
mg"
8
10
15
18
18
18
18
The similarity between these data and the values reported in Table 7,
page 3If., are striking. Obviously, the region of underloading which was
roughly assumed to terminate somewhere above 1.0 gpd/ft (if-0.7 ^/m /^ay)
appears to extend to 2.0 gpd/ft2 (8l.U J/m2/day). Above this point the ki-
netic coefficients appear to be uniform. Figures 27 and 28 show the rather
excellent correlation between predicted and observed ammonia profiles at the
selected steady-estate flow loading values.
It should be recognized that the KSS values as defined by this technique
are substantially higher than those reported in the literature for suspended
growths of Nitrosomonas, either as a pure culture or in activated sludge.
This circumstance is judged to be an indication of diffusional resistances
developing as the biological films increase in thickness.
-------
INF
20
Z16
tn
O
o> <
E12
K1 = 60
= 1 8
O
z
O
O
I
8
INF
3 4
STAGES
Figure 27. Comparison of predicted and observed
ammonia profiles at steady state.
-------
INF 1
INF
L=1.0
L=2.0
Kj =30
KSS=10
K1 =45
KSS=15
3 4
STAGES
Figure 27. (Concluded)
87
-------
10
~ 8
o>
o
s
LU A
cc 4
z
o
5
EFF
2 4 6 8 10 12 14 16 18
STEADY STATE AMMONIA CONC.(mgX^)
Figure 28. Correlation of observed and predicted
ammonia profiles at steady state.
20
-------
Once the unit is fully stabilized, the data may be treated in the fol-
lowing fashion:
C f f C
\ __ eii eff
—, -C»jr»' iv_ v — |Y
inf eff "IK + C IK + C
ss eff L %s °
K • V
where K =
The curve representing this equation is shown in Figure 28. Twenty-two
data points were selected from Table 9 as being representative of a fully
stabilized condition. These points are superimposed on the curve of Figure
28 and indicate excellent agreement. Obviously the completed curve will re-
quire additional flow loading data at higher values.
The level of substrate actually available to the average nitrifying or-
ganisms in the film is considerably less than the level in the bulk liquid.
It probably can be estimated as being the bulk concentration divided by the
Kss but at the present time, it can only be chosen indirectly.
To be fully predictive this kinetic model needs further elaboration. X
and M.max are assumed to be constants once the RBS system has reached steady
state. These quantities to date have not been measurable directly (as has
been noted). However, if these two terms are constants and the A/V term is
likewise constant for a given system, the K]_ must be directly proportional
to the Nitrosomonas concentration. Further study of the bio-film will be
necessary to elaborate this premise.
On the basis of the above facts, it would be ill advised to extend the
use of this model to other systems dissimilar in substrate composition, area
to volume ratios, varying proportions of heterotrophs and alkalinity or pH
differences.
-------
REFERENCES
1. Sawyer, G. N. and A. F. Ferullo. Nitrogen Fixation in Natural and
Laboratory Conditions. Trans. I960 Seminar on Algae and Metropolitan
Wastes. Robert A. Taft Sanitary Engineering Center, Cincinnati, Ohio.
Tech. Report W-61-3- P- 100-
2. Schloesing, T., and A. Muntz. Sur la Nitrification par les ferments
organismes. Compt. Rend. Acad. Sci., 1877- P- 892.
3- Winogradsky, M. S. Sur les Organismes de la Nitrification. Annales
Institut Pasteur (Paris), 1890". p. h.
k. Heukelekian, H. The Influence of Nitrifying Flora, Oxygen and Ammonium
Supply on the Nitrification of Sewage. Sewage Works J. , lk:9&+,
5- Meyerhof., 0. Untersuchungen uber den Atmungsvorgung Nitrifizierender
Bakterien, I. Die Atmug des Nitrabildners . Pf lungers Arch. ges.
Physiol., 161)-: 3 55, 196l.
6. Borchardt, J. A. Biological Waste Treatment Using Rotating Discs.
Biotechnology and Bioengineering Symposium No. 2, 1971- p. 131-
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90
-------
11. Abstract. Sewage Disposal Bulletin. City of New York, K. Allen, p. 14,
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33. Laudelout, H. , and L. van Tichelen. Kinetics of the Nitrite Oxidation
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36. Sawyer, C. N. , and L. Bradney. Modernization of the BOD Test for De-
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37.
Anon. Process Design Manual for Nitrogen Control. USEPA Technology
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92
-------
38. Chick, H. A Study of the Process of Nitrification with Reference to
the Purification of Sewage. Proc. Roy. Soc. (London), Series B,
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39. Eylar, 0. R., and E. L. Schmidt. A Survey of Heterotrophic Micro-
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pounds in Microorganisms. Biol. Rev., 38:530, 1963.
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1*3. Poduskajie, A., and J. F. Andrews. Dynamics of Nitrification in Acti-
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Treatment, Design and Operation. JSED, Proc. ASCE, 96(NOSA3):757,
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1*5- Balakrichnan, E., and W. W. Eckenfelder. Nitrogen Relationships in
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1*6. Heukelekian, H. The Effect of Carbonaceous Materials on Nitrification.
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1*8. Weng. C. N., and A. H. Molof. Nitrification in the Biological Fixed-
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50. Laudelout, H., P. C. Simonart, and R. Van Croogenbroeck. Calorimetric
Measurement of Free Energy Utilization by Nitrosomonas and Nitrobacter.
Arch. Microbiol., 63=256, 1968.
-------
51. Winogradski, S. Recherches sur les organisms de la nitrification.
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Bringman, G. Optimale Stickstoff—Abasung durch Einsatz von Nitrifi-
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(1962).
63. Private Communication with Brian Goodman, N.S.F. Package Aerator Proj-
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-------
6h. Jaworski, C. A., and S. A. Stanley. Excessive Nitrite Nitrogen in
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Removal. Water and Sewage Works, 122(6) :66, 1975-
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Process. .Presented at the annual meetings of the New England Water
Pollution Control Association in Kennebunkport , Maine, June 10-12,
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Nutrients— Part II. Water and Sewage Works, 122(11) :k8, 1975-
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Design Considerations for Supported Growth Systems. J. Water Poll.
Control Fed., k9(k):5b9, 1977-
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p. 1+27.
71. Lees, H. The Biochemistry of Nitrifying Bacteria In: Symposium on
Autotrophic Microorganisms. Cambridge University Press, London,
P- 81+.
95
-------
TABLE A-l. NITRIFICATION DATA FLOW LOADING = 0.25 gpd/ft2 - U-ft dia
Date
8/02
8/20
8/21
8/26
8/28
8/29
9/oU
9/09
9/11
9/12
9/16
9/18
9/29
10/01
10/06
10/08
10/10
10/13
10/15
X
Flow,
,0/min
1.1*
0.8
0.8
1.8
1-7
0.7
0.8
1-5
1.0
0.8
1.3
1.3
1.8
1.8
1.2
1.0
1.0
1-9
1.5
1.3
Temp . ,
°C
21.0
21.0
22.0
22.5
21.0
23.0
21.0
19.0
20.0
20.0
19.0
20.0
17.0
18.0
17-0
17.0
17.0
17-8
19.0
S
NIL*
9.U
11.0
10.0
lU.U
16.2
12.1*
12.1*
11.8
11-7
lU.o
13-5
11.8
13.0
11*. 1*
13.2
19.2
ll*. 5
12.9
19-3
13. 1*
1
N f
ox
6.6
U.I
3.1
3-0
2.8
2.6
2.5
2.2
1-5
0.6
0.9
0.2
U.3
2.1
7.5
3.8
U.6
U.6
9-6
U.2
s
NIL
0.7
0.2
0.2
1.9
2.5
1.2
0.8
0.6
1.2
0.9
1.0
1.0
0.7
0.8
13-5
16.6
13-5
9.U
11.0
U.i
2
N
ox
12. U
23.0
lU.O
lU.o
10.8
10.0
10. U
10.1
10.0
11.2
12.2
11.2
16.2
15.2
9.2
2.U
u.u
5-2
10.9
11.2
S3
NIL
O.U
0.2
0.2
l.U
1.9
0.8
0.8
0.5
0.6
0.7
0.6
1.0
0.9
0.7
0.2
0.3
o.U
O.U
0.5
0.7
N
ox
13-5
23.0
lU.o
lU.o
12. U
10. U
10. U
10.1
11.6
11.2
12.8
12.5
16.2
16.0
2U.O
17.8
22.7
18.8
20.8
15. U
s
NIL
0.2
0.2
0.2
l.U
1.0
0-5
0.2
0.2
0.7
0.9
O.U
0.8
0.7
0.5
0.1
0.1
0.3
0.3
0.1
0.5
U
N
ox
13.5
22.5
lU.o
lU.O
lU.O
11.0
10. U
10.5
11.6
11 2
13. U
12.9
15.2
15.0
2U.O
18.8
23.2
21.2
20.8
15-6
CJ Q
5 6
WH
o.U
0.2
0.2
0.9
1.0
0.2
0.2
0.3
0.6
0.8
0.3
0.7
0.7
0.3
0.1
0.1
0.1
0.3
0.1
o.U
N
ox
13.5
22.5
lU.o
13.6
15.2
12.0
10. U
11.0
11.8
12.0
1U.6
13.8
16.1
15.1
2U.O
17. U
23.1
18.8
20.8
15.8
NIL
0.2
0.2
0.2
0.5
0.6
0.5
0.2
0.8
0.6
0.5
0.3
0.6
0.6
0.3
0.1
0.1
0.2
0.3
0.1
o.U
N
ox
13-5
22.5
lU.o
lU.U
13.6
12.0
10. U
11.0
11.6
12.0
12.8
13-2
16.1
15.8
22.6
17.8
23.9
20.6
20.8
15.7
s
7
NH
o.U
0.2
0.2
0.5
0.6
o.U
0.2
0.8
0.7
o.U
0.2
0.6
0.9
0.7
0.1
0.2
0.3
0.3
0.1
o.U
N
ox
13-5
22.0
lU.O
lU.O
13.6
11-5
10. U
11.0
11.6
11.6
12.8
13.0
15.8
iU.6
22.6
17.8
23.1
18.7
20.8
15-U
|rJ
1
H
X
>
H
0
8
>
h|
1
p
H
m
*WIfe where used this term expresses NH-j mg/^ as N.
N where used this term expresses the sum of (MX + N02) mg/^ as N.
-------
VQ
2
TABLE A-2. NITRIFICATION DATA FLOW LOADING =0.5 gpd/ft - 4-ft dia
Date
10/17
10/20
10/22
10/24
10/27
10/29
10/31
11/03
11/05
11/07
X
Flow,
,0/min
2.8
2.8
2.8
2.6
1.5
2.8
2.0
2.8
3.0
2.8
2.6
Temp. ,
°C
15-5
16.2
18.0
17.0
15.0
16.0
13-5
18.0
18.5
18.8
16.7
Sl
NH *
5
12.0
9-4
13-5
11.0
i4.o
20.0
i4.o
19.0
12.6
14.6
i4.o
N T
ox
-U,3
5-5
4.4
11.0
12.1
6.0
3-7
15-1
5-3
4.6
7-2
S2 S3 S4
N^
12.0
11.4
—
0.9
0.4
1.0
6.8
1.6
1.4
7.4
4.3
N
ox
4.4
5.8
--
20-5
24.0
9.4
13.8
24.8
14.4
18.3
15-0
NH
1.3
0.6
1.0
0.2
5.4
0.6
5-0
0.8
0.7
7-3
1.3
N
ox
15-4
20.5
14.4
22.2
23.5
18.0
10.5
24.8
15.2
13-4
17.8
NH
0.4
0.4
0.4
0.2
0.4
0.4
0.2
0.4
0.2
0.4
0-3
N
ox
16.8
18.4
20.1
22.5
27.0
18.0
16.3
31-2
13.8
17.2
20.1
NH
3
0-3
0.4
0.3
0.2
0.4
0.4
0.2
0.3
-0.2
0.2
0.3
S
N
ox
16.5,
17.0
20.7
23.0
27-9
18.0
16.5
31.4
15.5
17-7
20.4
NHL
0.1
0.3
0-3
0.2
0.4
o.4
0.3
0.3
0.2
0-3
0.3
S6
N
ox
16.5
19-4
20.5
25.0
28.9
18.0
16.7
32.0
15.8
17-8
21.1
NIL
0.1
0.4
0.2
0.2
0.4
0.4
0.2
0.2
0.1
0.3
0.3
S7
N
ox
15.8
• 18.7
20.4
25.0
26.7
18.0
17-2
32.0
15.8
17-5
20.7
*NHz, where used this term expresses NHj mg/^ as N.
N where used this term expresses the sum of (NO, + NOp) mg/^ as N.
Q.X. *}
-------
TABLE A-3. NITRIFICATION DATA FLOW LOADING =1.0 gpd/ft - I*-ft dia
Date
11/19
12/10
12/19
12/22
12/24
12/26
12/29
12/31
1/02
1/05
& V07
1/12
1/14
1/16
1/21
1/23
1/26
1/28
1/30
2/02
2/04
2/06
X
Flow,
£/m±n
4.73
^•73
4.73
4.00
4.25
4.73
5.40
5-68
--
—
5.41
4-73
4.73
4.73
5.40
4.73
4.73
4-73
4.73
^•73
^.73
4.73
4.81
Temp . ,
°C
16.0
11.5
--
8.5
8.0
8.5
8.5
9-0
8.0
8.0
8.5
9-5
10.0
10.0
9.5
9.0
10.5
9-5
10.0
7.0
10.2
10.2
--
Sl
NH*
15-5
19-7
12.8
15-9
12.2
16.0
16.7
14.4
14.5
13.4
15.8
15-0
16.0
15.0
16.4
18.0
22.2
19.4
16.4
12.8
19.8
19-6
16.3
N r
ox
4.7
5-9
1.8
6.2
7.4
1.4
5.6
4.5
5-4
3-6
3-3
4.1
1.8
1.5
1.6
1-9
5.6
2.2
1.8
7.3
3.7
2.5
3.9
S
NIL
1-3
2.2
1.8
1.8
1.0
2.0
2.6
1.7
2.2
2.6
3.4
10.8
__
5-1
10.2
13.0
11.2
9-6
8.8
6.3
9-5
5-^-
5-4
2
N
ox
21.0
9-9
10.8
16.8
15.0
13.4
i4.o
15.0
15.0
9.0
9-6
11.0
--
13.2
9.5
io.4
11.4
9-0
9-4
11.5
12.7
12.4
12.4
S3 Sk S
NH
:5-4
0.9
0.9
0.9
0.5
0.7
1.0
1.0
1.0
1.0
1.8
1.1
0.8
1.0
4.0
8.6
11.4
5-0
5-1
2.8
3-9
2.5
2.8
N
ox
18.6
15-8
13-2
16.8
16.6
14.4
15.6
15.7
15-3
9.5
9-3
12.5
12.4
10.6
9.8
11.3
12.3
10.5
11.5
11.8
13-2
13-8
11.0
NIL
0-3
0.4
0-5
0.3
0.5
0.5
0.6
0-3
3-2
0.5
1.0
0.5
0.3
0.6
1.7
3-5
3-2
1.2
1-3
l.l
1.6
0.7
1.1
N
ox
26.0
18.0
10.6
i4.o
16.4
14.8
13.4
16.2
15.0
9-3
10.2
11.7
15-5
11.2
10.6
12.0
16.2
10.5
11.4
12.7
12.6
14.2
13.8
NIL
0.3
0.3
0.1
0.2
0.4
o.4
0.4
0-3
0.3
0.2
0.8
0.4
0.5
0.5
0.9
1.0
2.6
1.0
0.7
1.1
0.4
0.8
0.6
N
ox
26.3
18.1
9-0
16.0
16.2
14.8
16.2
17-3
16.5
10.2
10.4
11.9
15.5
12.2
10.3
13-6
16.0
11.8
11.8
13.8
15.2
12.3
14.3
NIL
0.2
0.3
0.1
0.1
0.3
0.3
0.3
0.2
0.2
0.2
0.3
0.2
0.1
0.4
0.5
0.6
1.4
0.6
0.4
0.7
0.4
0.3
0.4
S6
N
ox
24.5
18.0
10.2
17-0
16.6
14.0
16.0
17-5
16.0
10.7
10.8
10.5
15-7
12.0
10.0
13.0
15.6
10.5
12.0
13-5
15-3
13-8
14.2
S
7
NH
0.2
0.1
0.5
0.2
0.1
0.6
0.2
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.5
1.0
1.4
0.4
0.1
0.2
0.3
0.2
0.3
N
ox
25-7
18.5
13-4
16.0
16.6
14.6
16.0
18.0
16.7
10.8
11.4
13.0
16.1
12.9
11.0
13-2
17-0
11.4
12.5
14.5
14.8
14.9
15.0
*N!fe where used this term expresses NHj mg/,0 as N.
N where used this term expresses the sum of (MX + NOo) mg/,0 as N.
-------
\o
\0
2
TABLE A-U. NITRIFICATION DATA FLOW LOADING =1-5 gpd/ft - i+-ft dia
Date
2/09
2/11
2/13
2/16
2/20
2/23
2/25
2/27
3/01
3/03
X
Flow,
7-57
7.57
__
7-57
7-57
7.57
7-57
6.30
5-40
5.40
--
Temp.,
°C
_ _
11.5
11.5
__
12.5
10.5
13-0
13-0
11.6
11.0
—
S
NIL*
17.4
16.4
15.0
9-1
9-7
5-4
10.0
11.4
10.0
6.8
12.3
l
N T
ox
2.9
1.8
1-3
1.0
1-3
1.2
1.5
3-2
3-3
2.1
2.0
NIL
3-9
5-0
7.6
3-9
3-1
2.8
1.7
1.9
1-3
0.2
3.3
S2
N
ox
14.0
8.6
7-3
6.2
5-7
7.0
8.0
8.4
10.5
5-8
5.0
NIL
1.4
3-3
2.6
2.7
1.6
0.8
0.6
0.5
0.4
0.2
1.7
S
N
ox
13-8
11.6
7-9
6.5
6.8
8.0
9-9
9.0
12.5
6.0
6.5
i
I
NIL
0.6
2.0
1.0
0.8
--
0.3
0.3
0.4
0.4
0.2
0.8
\
N
ox
13-4
12.6
8.6
5.6
__
7-7
8.2
8.7
12.5
5.5
7-1
NH
0.4
0.8
0.6
0.4
0.3
0.9
0.2
0.4
0.3
0.2
0.4
S5
N
ox
13.9
13.0
9.6
7-5
7.6
8.1
9-3
9-8
11.6
6.0
7.6
NIL
0.4
0.7
0.4
0.1
0.2
0.1
0.2
0.3
0.2
0.2
0.3
S6
N
ox
12.3
13-6
8.5
6.0
7-0
8.1
9-7
8.8
9-2
5-3
7.8
NIL
0.2
0.4
0.5
0.2
0.2
0.1
0.1
0.4
0.2
0.2
0.2
S
7
N
ox
15.1
14.4
9.2
7.0
7.4
9.2
10.5
9-5
12.8
6.0
8.9
*NHz where used this terra expresses NHj mg/i as N.
N where used this term expresses the sum of (MX + N02) mg/^ as N.
-------
TABLE A-5. NITRIFICATION DATA FLOW LOADING =2.0 gpd/ft - k-ft dia
o
o
Date
3/10
3/12
3/15
5/17
3/19
3/26
3/29
U/05
U/07
U/l6
V19
U/21
U/28
V30
5/03
X
Flow,
,0/min
10.8
10.8
10.8
10.8
9.5
9-1
8.7
9-5
7-3
10.8
10.8
10.8
9-5
10.3
8.7
9-9
Temp.,
°C
11.0
11.0
11.5
10.0
lU.O
15.0
13.0
lU.O
15.0
17.0
17.0
15.0
lU.O
lU.O
. lU.O
--
sl
NH *
11.2
12.U
9-8
11.7
15.6
10.5
10.0
15-0
12.2
19.0
__
16.1
12. u
15.6
18.8
13.6
N T
ox
1.0
1.2
1.2
2.1+
1.6
0.8
2.3
8.3
2.3
2.5
--
2.1
3.0
5.6
2.7
2.7
S2
NIL
6.U
8.0
U.9
8.0
10.3
3.1
1-3
5.3
1.9
2.8
10.0
5-9
1.6
8.0
7-6
5.7
N
ox
7.0
6.2
7-3
5.1
5-7
8.6
11.2
22.0
9.1
12.2
17.8
9.8
10.8
12.3
10.0
8.9
S3 SU S5
NH
5-2
5-5
2.7
5-3
8;o
--
0.7
2.7
0.8
o.U
5.8
2-3
0.3
2.6
__
3-5
N
ox
8.1
8.6
9.0
7-5
6.6
--
10.2
19-5
9-0
1U.2
28.6
9-7
11.9
lU.U
—
12.1
NH
3.1
2.9
1-3
2.8
5.2
--
0.8
l.U
0.8
O.k
3.U
1.8
0.3
l.U
2.U
2.0
N
ox
8.8
9-6
10.1
9-1
8.2
--
10.0
23.0
9.0
lU.U
26.8
10.9
12.6
15.9
10.9
12.8
NHz
1.7
1.9
0.8
1-9
1-9
0.9
0-3
1.0
0.5
0-3
2.8
1.0
0.2
0.9
1.8
1.2
N
ox
10.5
10.6
10.5
10.2
9.U
8.U
li.l
20.6
9.0
1U.5
27-9
12.5
12.1
16.6
lU.2
13.2
S6
NH
3
1.0
1.1
0.5
0.8
0.9
0.5
0.3
0.6
0.8
0.3
2.U
0-5
0.1
0.5
1.6
0.8
N
ox
10.3
10.9
11.5
10. U
9.6
8.6
11.0
20.0
10.2
16.3
29-5
13-0
12.2
YJ.k
15-2
13-7
S7
NH
0.6
0.8
0.3
0.8
0.7
0.3
0.2
o.h
0.2
0.2
2.2
o.U
0.1
O.k
l.U
0.6
N
ox
11.1
11.2
11.9
10.6
10.1
9-5
11.8
25.2
11.1
16.5
30.3
15-U
12.7
18.6
15-5
1U.5
where used this term expresses NHj mg/j as N.
where used this term expresses the sum of (NO, + N02) mg/i as N.
-------
2
TABLE A-6. NITRIFICATION DATA FLOW LOADING = 2.5 gpd/ft - 4-ft dia
Date
5/10
5/14
5/19
5/21
5/24
5/28
6/01
6/07
X
Flow,
.0/min
15.0
16.0
16.0
18.0
15-0
17-5
18.0
18.0
—
Temp.,
°C
11.7
16.5
14.9
14.9
12.5
11.5
12.0
13.3
13.2
Sl S2 S
NIL*
8.6
13.8
10.1
12.2
11.4
12.8
14.2
14.4
12.2
N T
ox
3-5
3-1
2.2
1.1
6.5
6.6
3.4
1.5
3.4
NIL
3
2.8
9.6
7-2
7.4
6.4
7-1
8.6
7.0
7-0
N
ox
12.6
10.0
7-6
7-6
12.8
11.8
9-2
7.5
9-9
NIL
1.5
8.3
5-7
4.5
3.0
2.4
2.8
2.9
3.9
N
ox
12.6
11.5
8.7
9-1
14.1
16.0
15.1
ll.l
12.3
S4 S
NIL
0.9
4.2
3-5
2.2
1.1
0.6
0.6
0.8
1.7
N
ox
12.3
11.6
9-7
9-9
15 4
18.4
15-9
12.6
13.2
NIL
0.4
3-8
2.3
1.6
1.0
0.5
0.5
0.5
1-5
N
ox
12.7
11.7
11.4
11.4
15-9
18.6
17-4
13-2
i4.o
o o
S6 S7
NHL
0.3
1.4
1.6
0.7
0.5
0.3
0.3
0.3
0.7
N
ox
14.1
14.3
11.6
11.8
16.5
19-0
17-5
13.2
14.7
NIL
0.2
1.0
1.3
0.5
0.3
0.3
0.2
0.2
0.5
N
ox
14.8
14.6
12.0
11.4
16.0
18.4
17.9
13.8
14.8
*Ntfe where used this term expresses NHj mg/,0 as N.
N where used this term expresses the sum of (NO* + N02) mg/£ as N.
-------
M
2
TABLE A-7. NITRIFICATION DATA FLOW LOADING =3-0 gpd/ft - 4-ft dia
Date
6/16
6/18
6/21
6/23
6/25
6/30
7/02
7/05
7/08
7/19
7/21
X
Flow,
16.0
13-3
16.0
16.0
16.0
13.3
16.0
16.0
16.0
15,4
15.4
15.4
Temp.,
°C
18.0
19-5
18.0
18.0
19-5
--
17.0
19.0
21.0
19-0
20.5
--
NH *
15-8
13.8
21.5
13.5
8.0
8.9
10.5
6.9
10.1
9.6
7.6
10.6
s
N T
ox
3-7
11.0
1-7
1.7
:2.1
0.1
10.8
3.0
3.5
3-6
3-3
4.7
NH
13.0
5-2
20.8
11-3
5.6
6.4
6.5
3-5
6.9
3-7
4.2
6.7
S2
N
ox
6.2
17.4
2.8
3-3
4.8
1.2
14.4
7.0
7.1
10.5
7-4
8.7
NH
9.6
4.0
17.3
9.0
4.8
1-5
2.3
1.3
2.7
1.4
2.0
4.1
S
N
ox
10.5
19-0
6.3
5.8
6.3
0.9
17.8
10.1
11.2
14.0
10.5
11.7
NIL
6.3
1.1
10.2
4.4
1-3
0.5
0.6
0.4
0.6
0.5
0.9
1.8
S4
N
ox
12.1
23.0
11.8
12.0
9-4
' 0.3
19-9
11-5
13-9
15-7
11.9
14.4
NIL
4.6
0.7
9-7
2.9
0.9
0.4
0.5
0.2
0-3
0.3
0.8
1.2
S5
N
ox
14.5
24.2
12.4
13-1
9.4
0.1
20.1
11.7
14.4
16.2
11.8
15.0
NIL
4.5
0.4
7-3
2.0
0.3
0.2
0.5
0.2
0.2
0.3
0.6
1.0
S6
N
ox
15.2
24.5
13.8
13.6
9-7
0.1
20.7
12.0
14.8
15-5
12.4
15.4
NIL
3-2
0.3
5.0
1.8
0.1
0.1
0.2
0.1
0.1
0.1
o.4
0.7
S7
N
ox
15.8
24.5
17-2
13.8
9-7
0.1
21.6
12.2
15.0
16.0
12.6
15.7
*NHz where used this term expresses NHz rag/4 as N.
t
N where used this term expresses the sum of (NO, + NOg) mg/& as N.
-------
2
TABLE A-8. NITRIFICATION DATA FLOW LOADING = h.O gpd/ffc - h-ft dia
H
O
U)
Date
7/30
8/02
8/06
8/09
8/11
8/13
8/16
8/18
8/23
8/25
X
Flow,
J/rnin
1.6
1.6
1.6
1.6
1.6
--
1.6
1.6
!.k
1.6
1.6
Temp.,
°C
20.0
18.0
19.0
18.0
20.0
22.0
20.0
19.0
20.0
—
__
S
NH*
17-8
7-7
11. k
Q.k
15-5
16.2
12.5
11.0
11.0
13.3
12.5
1
N T
ox
2.8
2.6
2.3
8.0
--
3.U
3.8
1.7
—
--
3A
S2
NIL
11*. 2
5-6
7.U
5-7
13-0
12.6
9.0
8.0
10.3
10.8
9.8
N
ox
6.3
5-0
6.1
10.3
--
5-0
5.0
3-8
h.l
l*. 2
5-7
SO
O.
ML
10.8
3-2
5-1
3-6
10.3
10.0
6.2
5.8
8.0
10.1
7.1*
N
ox
10.0
7-0
8 2
12.8
—
5.i*
8.0
U.7
5.U
6.7
7-8
NIL
6.6
2.6
3.8
2.0
8.2
9-1
3.0
5.7
5.8
7-5
5-5
N
ox
1U.5
8.7
9-7
13.0
--
6.1*
10.3
5.0
6.6
8.2
8.1*
S5
NIL
U.7
2.0
2.7
1.8
5.6
5.2
1.8
2.8
6.k
7.2
k.O
N
ox
16.6
9-6
10.0
15.1*
--
7.U
12.3
6.8
8.0
9-3
9-3
S6
NIL
3.7
1.0
1.6
0.8
2.0
3.1*
1.1
2.0
k.I
5-7
2.6
N
ox
17-5
10.6
10.8
1^.2
__
9.6
12.8
8.0
9.0
11. h
11.8
S7
NH
2.6
0.8
1.2
0.6
l.i
3.0
0-7
1.0
2.h
3-7
1.7
N
ox
18.5
10.9
11.0
Ik. 8
--
—
13.5
10.0
9.1*
__
12.7
*NIfa where used this term expresses NHj mg/,0 as N.
'"N where used this term expresses the sum of (NO, + N0?) mg/,0 as N.
ox •>
-------
2
TABLE A-9. NITRIFICATION DATA FLOW LOADING =5.0 gpd/ft - U-ft dia
H
O
-£-
Date
9/03
9/07
9/08
9/10
9/13
9/15
X
Flow,
Jl/min
27.7
27.7
27.7
27-7
27-7
27.7
--
Temp.,
°G
19-5
20.5
20.5
18.0
20.0
20.0
—
S
NH*
3
13-0
17.0
20.0
17.6
16.6
26.9
18.5
1
N T
ox
5-7
5-7
1.5
U.I
5-1
2.6
U.l
s
NH
3
12.8
lU.i
17-6
16. U
16.0
25. U
17-0
2
N
ox
7-6
7.0
2.7
5-2
5-8
5.0
5-U
S
s.
3
NH
3
10.7
11.6
15-3
lU.O
15.0
2U.U
15.2
N
ox
8.3
7.8
U.I
6.3
6.3
U.8
5-8
NIL
3
8.6
9-6
13.0
12.1
13-2
22.8
13-2
U
N
ox
8.8
9-5
U.7
9.9
9.0
5.6
6.5
s
NIL
3
7.0
7-7
10.0
10.5
10.6
20. U
11.0
5
N
ox
10.2
10.0
6.8
10.0
9-5
6.U
7-1
g
6
NIL N
3 ox
5-U 11.5
5-6 11.5
7.5 8.8
8.6 12.5
8.0 11.5
18. U 8.0
8.9 7.8
S
7
NH N
3 ox
U.2 12.5
U.7 12.0
5.0 10.0
7.0 13.0
6.1 lU.O
1U.8 11.2
7-0 8.5
*NIfa where used this term expresses NHj mg/j as N.
N where used this term expresses the sum of (NO, + NO^) mg/^ as N.
-------
TABLE A-10. NITRIFICATION DATA FLOW LOADING =6.0 gpd/ft2 - 4-ft dia
Date
9/17
9/20
9/23
"9/27
9/29
10/01
10/05
10/07
10/13
10/14
10/15
10/19
10/20
10/21
10/22
10/25
10/26
10/27
10/29
11/01
X
Flow,
jg/min
32.4
30.7
--
—
31-5
31.5
31-5
—
31.5
32.4
31-5
__
30.7
29.8
30.7
--
34.4
33.4
33-4
33-4
31-9
Temp.,
°C
19-5
19-5
17.5
17.0
17.0
17-0
19-0
—
17.0
14.5
16.5
—
13-5
13-0
12.0
--
15.0
16.0
i4.o
15.0
16.1
SO
JD
NIL*
20.0
12.7
13.8
10.0
11.0
9.9
19.5
13.5
10.3
8.9
16.9
12.6
12.1
16.0
18.6
18.6
16.2
15.1
24.1
24.1
14.3
N T
ox
5.8
2.4
5.5
3.5
5-5
5-5
4.2
5-7
5-9
7.4
8.7
3-2
3.7
2.6
1.2
3-6
2.2
1.5
2.0
1.5
4.1
NIL
18.4
11,5
12.1
8.8
9-0
7-5
16.0
11.5
7-1
6.5
13.8
6.8
7-6
14.8
15-1
17.3
14.8
—
19-0
22.9
13.4
N
ox
6.8
3-5
6.8
4.9
8.1
7-2
7-5
10.4
8.6
9-3
10.5
9-2
6.6
4.5
4.7
4.9
3.8
5-3
3.1
3.2
6.4
S3
NIL
16.5
9.3
10.1
7.2
6.6
5.5
14.1
11.3
5-7
4.2
11.0
6.2
7-2
14.1
11-9
17.0
12.2
10.5
18.9
15.7
10.8
N
ox
9-6
6.0
8.2
6.0
1Q.5
9-0
9-7
11.0
9-9
10.9
11.8
9-9
8.5
5.4
6.0
5-2
8.0
6.0
4.6
9.0
8-3
S4
NIL
14.6
7.8
8.0
4.5
4.0
3-1
11.8
7-1
2.5
2.1
8.3
3-5
4.3
11.2
8.5
14.5
9-9
8.2
15.6
13-9
8.2
N NIL
ox 3
11.2 12.5
7-5 6.8
10.3 6.5
8.6 3-3
12 . 4 2.1
10.5 1-7
10.6 9.9
5.8 7-5
12.1 1.4
11.3 i.o
13-9 6.2
12.2 2.0
10.9 2.7
7-5 -9-5
7»5 6.0
7-2 13.5
9.2 9.0
7-5 7.8
8.3 15-5
10.7 11-5
9-8 6.8
S
N NIL
ox 3
13.0 11.4
8.1 5.0
11.9 ^-7
9-6 1-3
14.1 i.o
12.4 0.7
11.5 8.2
13-9 5.2
13-0 0.6
13.0 0.5
15.9 3-7
12.5 i.o
12.1 1.1
8.6 5-9
8.3 3-3
8.3 12.1
8.0 6.8
8.3 6.0
9.0 12.7
11.5 12.4
11.2 5.8
S6
N
ox
14.0
9.4
12.8
10.8
14.6
12.5
13.0
15.9
13.2
14.5
18.5
14.4
13.4
12.6
10.5
10.2
9.5
9-3
10.6
14.7
12.7
NH
9.4
3.4
2.8
0.9
0.7
0.5
7-0
2.0
0.4
0.4
2.2
1.1
0.9
4.8
1.8
10.3
4.8
3-7
10.6
5.8
3-7
S7
N
ox
14.6
10.2
14.2
11.0
15.0
13.3
14.3
11.0
13.9
14.5
20.9
12.0
13.7
13-6
14.4
10.8
12.7
10.6
12.8
14.8
13.4
*NHz> where used this term expresses NHx mg/^ as N.
N where used this term expresses the sum of (NO, + N02) mg/J as N.
-------
TABLE A-ll. NITRIFICATION DATA FLOW LOADING = 3-5 gpd/ft - 4-ft dia
Date
11/22
11/30
11/30
12/01
12/01
12/02
12/03
12/04
12/05
12/06
12/09
12/09
12/10
12/12
12/13
12/13
12/14
12/14
12/15
12/16
12/17
12/18
12/19
Flow,
^/min
23-3
23-3
14.9
9-5
20.4
18.6
18.3
18.3
18.3
18.3
18.0
18.3
18.3
18.3
18.3
14.5
18.9
18.3
18.9
18.3
18.3
18.3
18.3
Temp.,
°C
13-0
__
10.0
11.0
11.0
8.0
7.5
11.0
12.0
12 0
11.0
11.0
10.0
10.0
8.0
7-0
8.0
10.0
11.0
11.0
12.0
12.0
12.0
NH *
15.2
13-9
18.7
25.8
24.1
20.0
16.7
11.8
16.7
20.1
21.5
20.2
20.1
20.2
31-3
25-5
29.5
25.6
17-9
20.5
22.0
20.0
13.9
Sl
N T
ox
3-0
8.5
5-7
3-5
2.6
2.9
4.4
4.4
4.0
3.5
3-7
2-3
2.6
4.2
19.0
12.0
3.0
4.6
2.9
3.2
3-2
2.7
4.6 •
S2
NH
3
14.9
15.8
12.0
17-5
22.7
13.8
13.6
6.1
12.5
13-3
16.3
19.8
18.2
16.4
28.5
25.8
23-3
25.0
i4.l
17.0
16.4
14.5
10.1
N
ox
4.5
4.3
10.5
8.9
3-9
11.9
6.0
6.7
6.8
8.5
6.3
4.0
4.2
6.7
23.5
12.9
4.3
4.5
4.9
5.4
6.1
5-7
7-8
s.
NIL
14.8
8.7
8.6
14.5
20.5
15-1
12.1
5-2
10.3
7.8
13-9
16.6
17.0
15.0
27.3
25.1
20.5
24.0
12.5
14.6
14.4
12.3
8.0
5
N
ox
5-5
10.7
11.9
10.7
4.7
6.4
6.9
7.8
8.4
10.5
8.0
4.7
5-0
8.4
25.7
14.2
5.4
5.1
6.1
6.5
8.0
7.5
9.5
NH
10.2
5-7
5-3
9-3
18.0
9-0
9.8
2.8
6.9
3-7.
10.8
13-5
13.8
12.0
25-3
23.0
16.9
19.2
9-3
11.3
10.7
8.8
5-4
S4
N NH
ox 3
8.0 8.2
12.3 2.8
15-5 2.7
13-8 5.4
6.0 15.7
10.7 5.9
8.6 7-8
10.2 2.7
11.5 5-0
13.0 1.5
8.3 7-6
6.6 ll.O
7.2 -1.7
10.3 9-8
27.2 22.5
16.5 22.1
7-7 18.1
7.4 16.5
8.7 7-2
9-8 8.8
11-1 7-5
10.8 6.0
12.5 2.2
S
N NH
ox 5
9-3 5-3
15-5 1.1
17.4 1.2
16.8 2.2
7-4 13-5
12.6 3.1
10.4 5-5
12.0 1-7
14.2 2.0
15.0 0.7
11.5 5-4
8.2 8.3
8.6 8.5
12.0 6.2
28.5 19-0
20.3 19-5
8.8 10.5
9.4 12.7
10.2 4-3
11.4 4.8
11-5 3-4
11-5 2.3
12.9 i.o
S6
N NH
ox 3
11.6 4.3
16.3 0.9
17-7 0.8
19.4 0.8
8.8 12.9
14.2 2.0
12.2 4.8
14.4 2.4
17.0 1.6
15-5 0.5
13-5 4.5
9-8 8.1
ll.O 6.8
15.0 4.6
37.0 16.8
25.7 18.4
11.4 9-1
11.4 10.7
13.0 2.7
14.2 2.9
14.5 2.1
14.2 1.2
13.5 0.6
S
7
N
ox
13-0
17-3
18.4
15-4
9-6
15.0
12.8
15.6
18.1
15-7
13-7
11.4
12.1
17-3
39-0
26.8
12.5
12.8
14.0
16.9
15.0
15-5
14.2
*NJfc; where used this term expresses NH* mg/,g as N.
NOX where used this term expresses the sum of (NO, +
as N.
-------
TABLE A-ll. (Concluded)
o
—3
Date
12/20
12/2U
12/29
12/29
1/05
1/02
1/25
1/26
1/27
2/05
X
Flow,
.g/min
18.3
18.6
18.3
16.2
lit. 2
18.0
18.9
18.6
16.7
18.0
18.5
Temp.,
°C
12.0
9.0
9-0
9-0
10.0
9-5
10.0
—
7.0
7-0
9.it
SQ
o
ML*
26.1
23.2
15.1
24.0
16.8
23.2
20.2
20.2
22.0
20.2
20.7
N T
ox
it.it
26.2
it. 8
5-5
6.2
2.4
l.it
1.7
8.0
2.1
5-3
ML
17.5
15-5
9.1
12.9
9-9
20.6
16.9
15.it
19.8
17.8
16.2
N
ox
8.2
3.0
9-6
10.5
12.0
it. 6
3-7
it.9
10.7
3-7
8.1
S3 S4 S5
ML
lit.O
13-0
6.5
10.. it
7-0
20.8
lit. 2
13-6
I8.it
16.6
lit.it
N
ox
10.2
31.8
11.8
12.it
13.8
5-9
5.1
6. it
12.it
it. 8
9-5
NIL
9-7
8.6
2.7
5-9
2.6
16.8
12.9
10.0
15.it
13-2
10.2
N NIL
ox 3
13-5 6.2
34.0 it. 5
lit. 8 1.5
15.6 2.5
17.1 l.l
8.2 14.6
7-9 9-2
9-0 7-8
15-6 13.0
7-1 10.5
12.0 8.6
N
ox
13-9
38.1
15-5
17.2
17-9
10.4
9-7
11.0
18.2
9-1
13.8
NIL
2.5
1.9
0.7
0.9
0.6
12.0
6.1
5.2
9.2
6.1
5-9
S6
N
ox
15.4
39-6
16.2
18.2
18.8
12.8
12.9
lit. 6
20.5
11.6
16.1
NIL
1.2
1.2
0.4
0.6
0.5
9-9
it.O
2-3
7-5
3-7
4.5
S7
N
ox
17.5
42.1
15-7
18.8
19-1
14.4
15.0
16.2
21.7
13-5
17.1
-------
TABLE A-12. BIO-DISC SURFACE AREA AND PLOW COMPUTATIONS
FOR OPERATION OF SALINE PILOT PLANT
GEOMETRY
lU disc/stage at hi" diameter
2
— = 0.785 3.92 = 12. OU ftr/side
I).
2 sides = 2U.08 ft2
2k 08 x Ik = 337 ft2/stage
6 stages x 327 = 2023 ft2/unit
FLOW AND LOADING COMPUTATIONS
o
(1) 0.25 gal/ft /day or 1.33 -g/min
p
(2) 0.5 gal/ft /day or 2.66 f/min
Q
(3) 0.75 gal/ft /day or 3.98
(U) 1.0 gal/ft2/day or 5-32
O
(5) 1-5 gal/ft /day or 7-97
p
(6) 2.0 gal/ft /day or 10.60
(7) 2.5 gal/ft2/day or 13-29 Vmin
(8) 3-0 gal/ft2/day or 15-95
(9) U.O gal/ft2/day or 21.26
(10) 3.5 gal/ft2/day or 18.60 J/min
(11) 5-0 gal/ft2/day or 27.58 £,/m±n
(12) 6.0 gal/ft2/day or 31-90 £/min
108
-------
25
O
MD
L=0.25 gpd/sq ft
No. of Data Sets = 21
--O—-
N03-N
NH3-N
INF 1
3 4
STAGES
25
z
o»
e
"Z.
a:
z
UJ
u
o
o
L = 0.5 gpd/sq ft
No. of Data Sets = 13
INF 1
3 4
STAGES
6
Figure A-l. Profiles of nitrogen concentration in Saline pilot plant.
-------
L=1.0
No. of
gpd/sq.ft
Data Sets = 23
_—o <
3 4
STAGES
25
^20h-
•^
z
E
~ 15
10
UJ
U
8
o
L=1.5 gpd/sq.ft
No. of Data Sets =7
,x>- o"
0
3 4
STAGES
Figure A-2. Profiles of nitrogen concentration in Saline pilot plant.
-------
25
L = 2.0gpd/sq.ft
No. of Data Sets=9
t * A.
25
-20
L=2.5 gpd/sq.ft
No. of Data Sets =8
0
234
STAGES
OINF 1
3 4
STAGES
Figure A-3. Profiles of nitrogen concentration in Saline pilot plant.
-------
ro
25
-20
L = 3.0 gpd/sq.ft
No. of Data Sets = 11
25
20
L = 4.0 gpd/sq.ft
No. of Data Sets =10
34
STAGES
0
3
STAGES
Figure A-U. Profiles of nitrogen concentration in Saline pilot plant.
-------
25
L= S.Ogpd/sq.ft
No. of Data Sets = 5
25
20
N0-N --—
L- 6.0 gpd/sq.ft
No. of Data Sets - 20
INF
1234560 1
STAGES
Figure A-5- Profiles of nitrogen concentration in Saline pilot plant.
234
STAGES
-------
20
"Duration of Shock
H
HJ
f-
Stage No
1
TIME(hr)
Figure A-6. Run #1202—1-hr flow shock.
-------
h-
H
vn
20
o»
d
Z
O
o
I
to
X
10
Duration of Shock
234
TIME (hr)
Figure A-?. Run #1130—2-hr flow shock.
6
-------
20
Duration of Shock
4 5
TIME (hr)
8
Figure A-8. Run #1102—k-hr flow shock.
-------
H
H
Duration of Shock
TIME (hr)
Figure A-9. Eun #1026—1-hr strength shock.
-------
Duration of Shock
Oo
1 23456
TIME (hr)
Figure A-10. Run #1028—2-hr strength shock.
Stage No.
1
8
-------
H
H
VD
-30
5!
o>
*
o
§20
o
X
z
10
Duration of Shock
Stage No.
1
23456
TIME (hr)
Figure A-ll. Run $110U —1^-hr strength shock.
8
-------
TABLE B-l. NITRIFICATION DATA FLOW LOADING = 0.25 gpd/ft^
Date
8/15
8/18
8/20
8/21
8/26
8/28
8/29
9/04
9/09
9/11
9/12
9/16
9/18
9/20
9/23
9/25
9/27
9/29
10/01
10/16
10/08
10/10
10/13
10/15
X
Sl
COD SS
77 —
143 --
131 --
8l --
156 -
122 --
83 --
81+ —
84 --
88 --
91 _.
95 __
76 --
72 --
53 --
65 --
68 -
80 --
65 --
80 --
83 --
69 --
7U -
52 -
87 --
COD
6l
67
77
69
86
74
42
38
69
35
30
38
76
76
65
61
42
76
38
68
73
6l
78
48
60
S2
SS
— —
82
--
38
28
60
26
37
43
--
--
57
39
24
--
62
42
38
49
--
—
103
42
60
48
S3
COD
73
58
77
50
92
65
46
50
38
40
23
34
68
49
22
61
38
49
30
61
41
53
62
44
57
SS
— —
24
—
15
18
20
12
13
25
--
--
30
34
32
--
32
18
18
11
19
21
21
37
34
23
S4
COD
42
50
71
65
69
59
31
31
38
35
23
30
61
76
19
6l
42
49
27
42
44
33
63
32
47
SS
— «
28
—
9
21
18
12
9
35
--
--
34
37
29
—
56
19
12
19
22
25
30
23
35
26
S5
COD
54
8l
58
46
65
6l
54
32
35
31
23
30
53
6l
38
61
38
48
27
42
44
4i
50
36
46
SS
_ _
28
--
44
43
20
28
48
57
--
--
38
34
33
—
33
16
13
17
19
30
29
18
26
30
S6
COD ,
58
50
71
61
80
65
42
32
31
27
23
19
49
42
15
35
38
49
27
45
44
4l
69
40
44
SS
—
34
__
38
36
20
26
4o
45
--
—
31
31
46
—
4o
19
10
17
24
30
30
32
16
30
S7
COD
—
4o
58
42
62
53
50
42
35
35-
20
12
46
61
38
46
45
49
27
38
44
37
58
44
,42
SS
—
16
--
5
37
9
9
7
15
--
--
19
21
—
—
21
15
11
6
24
__
17
33
19
17
M
X
CQ
t)
CO
o
H
a
CO
O
o
Si
CO
M
H
CO
t-i
H
-------
2
TABLE B-2. NITRIFICATION DATA PLOW LOADING =0.5 gpd/ft
H
ro
H
Date
10/17
10/20
10/22
10/24
10/27
10/29
io/3l
11/03
11/05
11/07
X
Sl
COD SS
50 —
59 __
55 --
45
61 -
105 —
39 —
43
8l -
75 —
63 --
S2
COD
50
59
55
45
57
105
20
h6
35
75
56
SS
ho
35
29
?h
26
50
36
42
37
O O» O
345
COD
25
59
42
h9
hh
73
50
39
43
70
h9
SS
26
12
14
hh
12
18
Ll
12
10
11
17
COD
33
50
61
36
77
23
43
43
63
hi
SS
28
11
21
26
15
20
25
21
21
10
56
COD
50
49
52
97
31
39
h6
82
53
SS
23
36
26
--
22
22
17
17
60
44
29
S6
COD
63
h2
65
56
60
23
43
46
86
53
SS
36
32
17
22
19
17
12
16
17
23
21
S7
COD
29
40
53
88
27
__
35
73
hi
SB
25
29
20
hh
11
14
15
12
23
34
23
-------
TABLE B-3. NITRIFICATION DATA FLOW LOADING =1.0 gpd/ft
H
ro
Date
11/19
12/19
12/22
12/21*
12/26
12/29
12/31
1/02
1/07
I/Ik
1/16
1/21
1/23
1/26
1/28
1/30
2/02
2/04
2/06
X
Q Q O C Q
bl S2 S3 S4 S5
COD
86
59
67
66
8k
80
39
55
118
106
51
11*1
120
82
97
89
86
86
89
83
SS COD
90
31
39
66
52
108
43
51
71
—
21*
— 208
85
80
101
120
90
78
82
77
SS
50
16
39
15
10
18
29
^5
Ik
--
56
56
13
21
15
57
ko
--
—
31
COD
55
43
27
50
68
80
31
kl
98
18
2k
137
101
70
66
101
71
102
66
69
SS
3^
33
27
30
18
45
19
25
11
38
22
k9
31
17
3^
58
83
--
—
31
COD
kl
92
kl
k2
8k
ko
2k
39
75
67
31
110
85
70
89
70
90
9k
85
68
SS
19
10
34
33
^3
29
27
25
24
27
33
31
17
17
26
36
43
--
—
27
COD
71
27
59
56
56
20
39
24
106
51
20
102
70
82
66
70
71
9k
70
60
SS
28
15
68
20
42
43
21
23
57
46
33
65
44
--
70
48
90
--
--
42
S6
COD
48
kl
31
84
48
^3
27
35
75
27
24
67
70
66
70
50
47
63
7^
55
SS
30
69
32
20
25
20
7
35
56
33
31
79
44
38
38
33
31
--
--
58
S7
COD
63
27
27
60
60
16
16
24
67
35
20
71
Ik
5U
70
—
86
63
5^
50
SS
3U
21
32
15
21
16
10
18
23
24
22
35
25
27
26
30
35
--
--
24
-------
IX)
U)
2
TABLE B-4. NITRIFICATION DATAILOW LOADING =1.5 gpd/ft
Date
2/09
2/11
2/13
2/16
2/18
2/20
2/23
2/25
2/27
X
Sl
COD SS
20
82 —
85 --
39 --
31 —
74 -
39 __
55 -
39 __
52 --
S2
COD
6
50
66
43
121
70
47
62
35
56
SS
— —
2
36
50
29
37
20
26
40
33
S3
COD
5
58
82
66
39
51
55
23
4
43
SS
_ _
47
44
42
39
30
25
38
41
38
i
COD
3
66
27
62
35
__
31
27
35
36
k
SS
_ _
36
39
44
—
—
27
31
31
35
S5
COD
2
58
47
43
23
43
39
27
12
33
SS
— —
42
32
16
4l
21
25
37
4l
32
S6
COD
2
50
39
27
58
43
27
47
63
40
SS
— —
49
43
39
33
34
27
35
58
40
S7
COD
2
70
47
31
58
43
31
35
59
42
SS
_ _
33
17
20
27
15
19
23
30
23
-------
IX)
TABLE B-5. NITRIFICATION DATA FLOW LOADING - 2.0 gpd/ft2
Date
3/10
3/12
3/15
3/17
3/19
V°5
1*/16
l*/21
V30
X
sl
COD SS
1*8 --
1*0 -
88 --
1*1* --
1*1*
63 --
56 --
96 -
1*6 --
58 -
S2
COD
2k
32
36
39
38
1*6
1*1*
1*8
32
38
SS
25
26
20
18
22
1*5
--
51*
27
30
a
COD
__ _
16
36
33
38
35
21*
36
28
31
5
SS
32
33
30
22
25
65
__
1*1
32
35
Sl*
COD
20
32
38
38
38
31
21*
36
32
32
SS
1*0
38
30
21*
21*
1*7
—
90
1*0
1*2
S5
COD
20
16
36
27
33
1*6
28
28
32
30
SS
1*2
33
37
29
37
U7
—
50
29
38
S6
COD
16
__
23
27
33
27
36
1*2
1*0
29
SS
37
1*3
29
29
1*2
--
--
77
33
in
S7
COD
16
--
23
27
33
27
1*0
56
20
28
SS
19
18
21*
19
18
1*5
--
38
29
26
-------
TABLE B-6. NITRIFICATION DATA FLOW LOADING =2.5
Date
5/10
5/1^
5/19
5/21
5/2^
5/28
6/01
6/07
X
Sl
COD SS
Uo -
36 -
56 -
60 —
56 -
1+7 --
147
55 --
50 —
S2 S \
COD
37
28
36
52
52
36
37
39
ko
SS
2k
33
23
25
—
—
—
—
26
COD
37
28
32
k&
kQ
32
28
31
36
SS
30
25
25
35
—
—
—
—
29
COD
35
2k
36
148
W3
28
2k
29
29
SS
20
28
36
38
—
—
—
--
3^
S5
COD
37
2k
32
^0
kk
32
32
31
31
SS
30
25
Ui
ito
—
—
—
--
3^ ~
S6
COD
35
2k
28
ko
kk
2k
2k
28
31
SS
27
23
38
35
—
—
—
__
31
S7
COD
32
20
28
36
36
20
2k
20
27
SS
20
22
23
33
—
—
—
—
25
-------
2
TABLE B-7. NITRIFICATION DATA FLOW LOADING =3.0 gpd/ft
H
ru
o\
Date
6/16
6/18
6/21
6/25
6/30
7/02
7/05
7/08
7/14
7/19
7/21
X
si
COD SS
51 __
51 _.
82 --
51 __
27 -
43 --
54 _.
54 ..
51 __
47 --
46 --
50 --
S2
COD SS
53
51
74
51
23
35
46
50
47
39
46
45
s
COD SS
43 --
47
55
47
20
35
46
I£
43 --
27
38
40
S4
COD SS
39
39
43
43 --
20
31
42
42
35
27
42
37
S5
COD SS
39
35
47
39
20
27
38
35
35
23
42
34
S6
COD SS
35
31
^3 __
39
20
27
35
35
31
23
42
32
S7
COD
35
27
31
35
16
23
35
31
31
—
36
29
SS
__
--
--
--
--
--
—
--
--
—
--
__
-------
rv>
2
TABLE B-8. NITFICIATION DATA FLOW LOADING = h.O gpd/ft
Date
7/26
7/30
8/02
8/06
8/09
8/11
8/13
8/16
8/18
8/23
8/25
X
sl
COD SS
50 —
5U
k2 —
38 -
25 --
36 -
36 -
51 -
Ul
2k —
hh -
ho —
S2
COD SS
^)lj, — —
Slj. «.-.
30
3U
35
32
32
U7
36 -
2h
ho
38
s,
COD
38
U2
30
h2
31
32
32
ho
33
32
Uo
36
J Sh
SS COD SS
._ ju ..
U2
22
U2
25
28
26
hh
20
2h
36 -
31
S5
COD SS
3U -
38
20
U2
35
28
20
Uo
16
28
32
30
S6
COD SS
28
3U
16
27
31
20
20
Uo
20
20
32
26
S7
COD
2U
3U
16
27
19
20
16
Uo
16
20
20
23
SS
__
__
—
—
—
—
__
__
__
—
—
•* —
-------
oo
TABLE B-9. NITRIFICATION DATA FLOW LOADING =5.0 gpd/ft
Date
9/03
9/07
9/08
9/10
9/13
9/15
Sl
COD SS
31 --
38 -
31 --
35 --
31 —
35 --
S2
COD SS
27
35
23
27
27
35
s
COD SS
27
35
23
27
27
31
sl
COD
27
31
23
23
27
31
S5
SS COD SS
27
27
19
23
23
29
S6
COD SS
23
27
19
19
23
27
S7
COD
23
21
15
19
23
23
SS
__
--
--
—
--
--
33 __ 29 — 28 -- 27 — 25 -- 23 -- 21
-------
ro
2
TABLE B-10. NITRIFICATION DATA FLOW LOADING =6.0 gpd/ft
Date
9/17
9/20
9/23
9/27
9/29
10/01
10/05
X
S!
COD SS
17 —
35 --
U3
3U
18 —
38 -
32 --
31 —
S2
COD SS
17
31
kl
27
15
—
3^
28
S3
COD SS
17
31 -—
21
27
18
3^
31+
26
sl
COD
18
27
33
27
10
29
32
25
* S5
SS COD SS
18
27
33
22
11
32
30
2k
S6
COD SS
18
23
25
C~- J_ ™ ™*
lU
29
2U
22
s.
COD
13
23
25
21
17
26
2k
21
7
SS
_ ..
—
—
—
—
--
—
__
-------
TABLE C-l NITRIFICATION DATA FLOW LOADING =0.25
U)
O
Date
5/11
5/17
5/28
6/01
6/04
X
Lag
NH
0.2
0.2
0.3
0.3
0-3
0-3
oon S
NH * N f
3 ox
0.6 —
0.1
0.1 19.0 1.6
o.i 33.0 o.i
o.i 18.5 3.1
--
S2
NH N
3 ox
1.8 7.2
5-5 10.2
9.6 11.7
5.4 14.3
4.7 10.5
4.4 10.5
S
NH
0.8
3-3
8.4
3.8
3-9
3-0
3
ox
6.9
11.2
11.9
14.9
13-2
11-5
s
NH
0.7
1-3
5-8
1-5
1.1
1.1
4
'N
ox
7-4
12.3
15.0
17-1
18.9
13-9
S
NH,
3
0.3
0.7
4.4
0.7
0.5
0.6
5
ox
7.4
13-1
15-3
17-3
18.0
13-9
Q Q
S6 S7
NH
0.3
0.4
3-5
0.6
0.3
0.4
N
ox
7-1
12.6
15-3
17-5
19-2
14.1
NH
0.3
0.4
3-1
0.4
0.2
0.3
N
ox
7-6
13-1
16.0
17.8
20.4
14.7
tNox where used this term expresses the sum of (NO^ + N02) mg/.g as N.
H
X
O
CQ
t-3
to
where used this term expresses NRj mg/^ as N, w
-------
TABLE C-2. NITRIFICATION DATA FLOW LOADING =0.5
H
U>
Date
6/08
6/22
6/25
6/29
7/02
7/09
7/13
X
Lagoon
NH '
0.6
0.6
0-3
o.u
0.3
0.6
0.7
0-5
N
ox
0.2
0.1
--
0.1
0.1
0.1
0.1
--
Q O
Sl S2
NH *
16.6
15-1
12.9
12.0
18.8
11.2
ll.l
13-9
N f
QX
0.2
1.4
—
1.0
3.0
2.1
2.8
1.8
NH
5-6
8.6
k.6
k.l
9-2
4.o
4.8
5-9
N
ox
9-0
8.3
—
11.0
11.2
9-7
8.2
9-6
S
NH
4.0
7-3
3-5
3-6
8.0
2.5
3-4
4.6
3
N
ox
10.2
10.0
—
12.2
13-1
11.2
10.2
11.1
O 0
NH
3
1.8
6.8
1.1
1.6
3-0
1.2
2.4
2.5
N
ox
12.6
10.5
—
14.8
17-1
13-0
10.2
13.0
NH
1.4
3-2
0.6
0.8
1.0
1.1
0.7
1-3
N
ox
13-0
13.0
__
15-0
1-9-3
13-0
12.7
1A.3
S6
NH
1.0
2.1
0.4
0.4
0.5
0-5
1.1
0.9
N
ox
13-5
13-5
—
15-1
20.1
13.4
13-2
Ik. 7
S7
NH
0.8
1.1
0.3
0.5
0.4
0.5
0.4
0.6
N
ox
13-5
13-9
--
15-5
20.4
13.5
13.3
Ik. 9
where used this term expresses Mfe mg/£ as N.
NOX where used this term expresses the sum of (NO, + N02) mg/J as N.
-------
TABLE C-3. GENOA TEMPERATURES, °C
Date
1/05
L/06
1/08 (7 pm)
1/08
1/09
1/09 (7 pm)
1/12
1/15
1/19
1/22
1/27
2/05
2/10
2/13
2/18
2/20
2/2U
3/02
3/08
3/11
3/17
3/23
3/25
3/30
U/02
4/06
V°9
V13
U/16
U/20
V23
V2?
5/06
5/11
5/1^
5/17
5/24
Outside
-7
-2
-10
-13
-13
-12
-3
-4
-0.5
-6
-5
-6
7
9
12
9
8
1+
h
3-5
-l
13
17
25
13-5
13-5
10.5
16.5
28
19
17-5
9
9
19
22
20
23
Inside
1+
8
2
-2
-3
13
7-5
7
7.5
6
10
12
10
9
11-5
11
9
9-5
8
11
10
13-5
17-5
20
17
16.5
16.5
16.5
22.5
19
18
15-5
15
17
19
19
19
Lagoon*
Frozen
Frozen
Frozen
Frozen
Frozen
Frozen
Frozen
Frozen
Frozen
Frozen
Frozen
Frozen
Frozen
Frozen
50% frozen
Free of ice
3
6
U.5
k
2
10
13
15
8-5
8
11-5
12-5
20
20
18
9-5
Hi
18
18.5
20
19
Inflow1"
(Stage 1)
0
0
0
0
0
0
0+tank thawed
0+tank thawed
0+tank thawed
Tank 3°
0
0-1
3
5
7
6
U
6.5
4.5
k
2
11
13
15
11.5
15
15-5
12
19
20
16.5
9-5
15
16.5
18
18
18
Overflow
(Stage 6)
—
--
--
--
--
--
--
__
--
--
0
1
3
5
7
7
h
7
5
--
__
11
lU
16
13
16
15-5
12-5
19
19
16
9-7
15
16
18
18
18
*Lagpon temperatures taken near shore and near lagoon overflow.
"*"Tank temperatures of 0°C usually meant some ice in tank.
132
-------
APPENDIX D. PILOT PLANT LAYOUT
TABLE D-l. SPECIFICATION FOR REACTORS
1. Tank—steel epoxy coated
5'-U" wide, 2'-o" deep, 9'-U" long. The tank was braced and sup-
ported on 2' legs of angle Iron. Two 1" nipples welded to the tank
and provided with male pipe thread.
2. Concrete fillets 15"x 15" and 3"x 3" cast of light weight concrete coated
with paraffin and 9" long. Thus two fillets slip into each stage to
support the removable partitions (12 large and 12 small required).
3. Tank fitted snugly with five 1/2" portable partitions. These will be
supported by the concrete fillets on' each side. All to be sealed in
place with plastic modeling clay. A 1" hole will be cut at the point
indicated on Figure D-l.
k. Tank will be equipped with 3" channels welded to each end to support 1"
ball bearings and 1" steel shaft.
5. Shaft to be equipped with 90 discs, 1/2" thick, and V-0" diameter.
Discs to be constructed of foamed polystyrene at a density of
~ ^ lb/ft-5. Spacing in each stage is as follows:
each disc = 1/2" 15 at 1/2" = 7-5"
each space = 5/8" ^ at 5/8" = 8-75"
end clearances = 1" 2 at 1" = 2.0"
Total = l'-6-yV
6 such stages = 109-1/2"
5 partitions at 1/2" = 2-1/2"
Total inside
dimension = 112
6. The 1" steel shaft shall be equipped with a chain drive and sprockets. A
variable speed motor will provide rotation with continuously varying
speeds up to at least 12 rpm.
7. Seven sampling ports shall be provided at the points indicated on Figure
D-2. These shall consist of stuffing boxes which will permit the in-
sertion of glass sampling tubes into the reactor at points 2-6.
Points 1 and 7 shall consist of 3/8" pipe fittings tapped into inlet
and outlet nipples.
133
-------
I "opening in each
partition for
passage of flow.
CROSS SECTION OF REACTOR
14 Discs/Stage
2
i
3
i
4
i
5
i
LONGITUDINAL CROSS SECTION
Figure D-l. Rotating biological surface units.
-------
inlet-HB
I
s
1, L,
tt
\
)
t :
t
h
i
A
*>
r u
a^o
outlet
s s
6
Sampling pts. (S, -S2... S7)
Six Stages in Series
inlet
S
Three Stages in Series
I
s?
inlet-
»X)I
outlet
Two Stages in Series
Figure D-2. Cross section of reactor.
135
-------
|«*-6" Plexiglass Tube
RBS
Sampling
Pump
2" Overflow Weir
Lin«
Synchronous
Timer
2 Inlet Baffle
Effluent
to one
Gallon
Sampling
Jug
8 1/4"
41/2"
To 50 Gal lo
Sludge Drurr
a-
Solenoid Valve
(Normally Open)
Figure D-j. Plan of settling tube sampler.
136
-------
1.0 200<
0.75 150
o
O
u
o
0.5glOO
cc
LJ
O
<
CC
0.25 50
Stage No.
/•?v2
b
A
^
0 0
'4 AA-
y^yv
^•-
1
I
•^8=*
•i^-v
^£^
-£*
2
I
3TIME(|r)
5
I I
6
I
5 _6
T/t
8
10
Figure D-h. Six-stage tracer study.
13T
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-78-061
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
NITRIFICATION OF SECONDARY MUNICIPAL WASTE EFFLUENTS
BY ROTATING BIO-DISCS
5. REPORT DATE
June 1978 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Jack A. Borchardt, Shin Jon Kang, and Tai Hak Chung
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
University of Michigan
Ann Arbor, Michigan 48109
10. PROGRAM ELEMENT NO.
1BC611, SOS#3, Task D-l/23
11. CONTRACT/GRANT NO.
R-803407
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory—Cin.,OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final. Jan. 1975-Oct. 1977
14. SPONSORING AGENCY CODE
EPA/600/14
15. SUPPLEMENTARY NOTES
Project Officer:" Edward J. Opatken 513/684-7643
16. ABSTRACT
This study was conducted to determine the effectiveness of nitrifying secondary
effluent with rotating biological surfaces (RBS). Two municipal effluents were
evaluated; one was from a high rate trickling filter and the other was from two-stage,
flow through lagoon.
RBS pilot plants were installed at both of the treatment plants to provide a
continuous flow of secondary treated effluent. Ammonia-nitrogen, nitrite and
nitrate-nitrogen were monitored along with other chemical constituents to determine
what effect a change in loading, staging,pH, alkalinity, temperature, speed of
rotation,and shock loads had on the performance of the RBS-
The RBS pilot plant at the high rate trickling filter plant provided satisfactory
results which showed the effect on effluent ammonia-nitrogen reductions by operational
changes at the RBS pilot plant. The RBS pilot plant at the lagoon system encountered
operating difficulties which resulted in an early cancellation for this phase of the
project.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Nitrification
Wastewater
Rotating biological
surfaces
Hydraulic loading
Temperature variation
Ammonia reduction
Mass loading
Trickling filter process
Lagoon system
13B
3. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)'
Unclassified
21. NO. OF PAGES
152
20. SECURITY CLASS (Thispage}
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
138
U.S. GOVERNMENT PRINTING OFFICE: 1978-J 757-140/1339
-------
1.0 200
0.75 150--
o
O
O
0.5glOO
a:
LU
o
<
cr
0.25 50
1 2345.6789 10
T/t
Figure D-U. Six-stage tracer study.
137
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-78-061
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
NITRIFICATION OF SECONDARY MUNICIPAL WASTE EFFLUENTS
BY ROTATING BIO-DISCS
5. REPORT DATE
June 1978 (IssuingJDate)
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Jack A. Borchardt, Shin Jon Kang, and Tai Hak Chung
8. PERFORMING ORGANIZATION REPORT NO,
9. PERFORMING ORGANIZATION NAME AND ADDRESS
University of Michigan
Ann Arbor, Michigan 48109
10. PROGRAM ELEMENT NO.
1BC611, SOS#3, Task D-l/23
11. CONTRACT/GRANT NO.
R-803407
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory—Cin.,OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final. Jan. 1975-Oct. 1977
14. SPONSORING AGENCY CODE
EPA/600/14
15. SUPPLEMENTARY NOTES
Project Officer:" Edward J. Opatken 513/684-7643
16. ABSTRACT
This study was conducted to determine the effectiveness of nitrifying secondary
effluent with rotating biological surfaces (RBS). Two municipal effluents were
evaluated; one was from a high rate trickling filter and the other was from two-stage,
flow through lagoon.
RBS pilot plants were installed at both of the treatment plants to provide a
continuous flow of secondary treated effluent. Ammonia-nitrogen, nitrite and
nitrate-nitrogen were monitored along with other chemical constituents to determine
what effect a change in loading, staging,pH, alkalinity, temperature, speed of
rotation,and shock loads had on the performance of the RBS-
The RBS pilot plant at the high rate trickling filter plant provided satisfactory
results which showed the effect on effluent ammonia-nitrogen reductions by operational
changes at the RBS pilot plant. The RBS pilot plant at the lagoon system encountered
operating difficulties which resulted in an early cancellation for this phase of the
project.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Nitrification
Wastewater
Rotating biological
surfaces
Hydraulic loading
Temperature variation
Ammonia reduction
Mass loading
Trickling filter process
Lagoon system
13B
3. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
152
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
138
U.S. GOVERNMENT PRINTING OFFICE. 1978-J 757-140/1339
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