USA-USSR
                             WORKING GROUP
                            ON THE PREVENTION OF
                            WATER POLLUTION
                           FROM MUNICIPAL AND
                          INDUSTRIAL SOURCES
                       Vodgeo Moscow, USSR
                      August 23-24, 1976
  SYMPOSIUM ON
 INTENSIFICATION OF
 BIO-CHEMICAL
TREATMENT OF WASTEWATERS
 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 'WASHINGTON DC 20460

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USA-USSR
WORKING GROUP
on the
Prevention of
Water Pollution
from
Municipal and
Industrial Sources


Symposium on
Intensification of
Bio-Chemical
Treatment of
Wastewaters

Vodgeo
Moscow, USSR
August 23-24, 1976

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                                               INDEX
Preface                                            1

Opening Address - Mr. John T. Rhett                 2

Papers Presented at the USA/USSR
SYMPOSIUM

Yakovlev, S.V., Skirdov, I.V., Rogovskaya, C.I.,
and Shvetsov, V.N. (Vodgeo), Kinetics of
Biochemical Oxidation                              4

Cywin, Allen (US EPA), Chemical Additions to
Biological Treatment of Petroleum Refinery
Wastewater                                        16

Shifrin, S.M., Mishookov, E.G., Ivanov, G.V.
and Golookovskaya, E.K. (Leningrad), The
Trends in Intensification in Biochemical
Treatment of High Density Wastewater              22

Lacy, William (US EPA), Steel Industry
Wastewater Treatment Using Biological-
Chemical Technology                              25

Gerber, V.Ya (Bashkirian Scientific Research
Institute of  Petroleum Refining, USSR),
Facilities Improvement for Biochemical
Treatment of Petroleum Refinery  Wastewater         30

Rosenkranz, William (US EPA), Biological
Methods for Control of Nitrogen in Municipal
Wastewaters                                      32

Skirdov, I.V., Shvetzov, V.N., Bondarev, A.A.,
Lurje, B.I.,  Bereykina, N.G., Katchkova, S.E.
(USSR), Operation Experience of Oxytanks           36

Sebastian, Frank and Lachtman, Dennis
(Envirotech), Improvements for Kraft Pulp and
Municipal Treatment Processess                    41

Yakovlev, S.V. and Karjukhina, T.A. (USSR),
Biological Wastewater Treatment in the Presence
of Steroid Compound                               50
Harper, Fred (Orange County Sanitation
Districts, California) A Comparison of
Conventional Activated Sludge Process and Pure
Oxygen Activated Sludge Process for a 75 MOD
Secondary Treatment Facility                       54

Skirchiavichus, A.L. (The Kaunas Polytechnic
Institute of Snechkus A.) Studies of Artificial
Aeration in the Lithuanian  SSR                     60

Adams, Carl (Associated  Water and Air
Resources Engineers, Inc) and Sumner, Billy
(American Consulting Engineers Council, Barge,
Waggoner, Sumner and Cannon), Wastewater
Treatment Concerns of the  Organic Chemicals
Industry in the United States                       62

Skirdov, I.V., Shvetzov, V.N., Morosova, K.M.,
Gubina, L.A. (USSR), Biochemical Treatment of
Highly Concentrated Wastewaters From Wool-
Scouring Operations                               70

Love, William (Hampton Roads Sanitation
District, Norfolk, Virginia), Analytical and
Process Improvements in  Biological Treatment of
Municipal Wastewaters                             74

Ysrshov, A., Kyghel, M., Zemlyak, M.
(Candidates of Sciences), Development and
Improvement of the Municipal Sewage Biological
Treatment Facilities                                78

Protocol                                         80

Appendix I  Participants                          81

Appendix II  Reports                             82

Appendix III Program                            82

Appendix IV Itinerary                            84
                                  U.S.  Environmental Protection  Agency
                                                     M

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               PREFACE

  The third cooperative USA/USSR symposium on the
Intensification of Bio-Chemical Treatment of Wastewaters
from Municipal and Industrial Sources was held in Mos-
cow, USSR at the Vodgeo headquarters on August 24
through 25,  1976.  This  symposium  was conducted  in
accord with the protocol of the Fourth Session of the Joint
USA/USSR Commission held in Washington, D.C. from
October 28 through 31, 1975.
  This  symposium was sponsored  under  the auspices of
the Working Group on the Prevention of Water Pollution
from Municipal and Industrial Sources. The United States
delegation was headed by John T. Rhett of the United
States Environmental Protection Agency and the Soviet
delegation by Professor S.V. Yakovlev of the Department
of Vodgeo in the Soviet Union.
  The fifteen papers that were  presented at the symposium
(seven US and eight USSR) are reprinted in English in this
volume.
  This  volume is reprinted in  English in  accord with the
protocol signed by the delegation leaders on September 4,
1976 in Moscow, USSR.

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 OPENING

 ADDRESS

John T. Rhett

Introduction

  This third symposium of the U.S./U.S.S.R. "Working
Group  on the  Prevention  of  Water  Pollution  from
Municipal and  Industrial  Sources"  represents another
milestone in the advancement of cooperation between our
nations in improvement of the earth's environment. It is
said that cooperation in environmental matters can serve as
a model of how two countries can cooperate for the mutual
benefit of themselves and of all nations. Certainly this has
proven to  be so in our group where so much progress has
been  made so swiftly in  the  areas  to  which  we have
addressed  ourselves.
  It is especially significant to the world that our activities
have  been directed  not only to municipal  treatment of
sanitary wastewaters, but also to industrial wastewaters. As
our countries  are the  two nations with  the largest gross
national products of the world we have the greatest need to
treat industrial wastes as well as the greatest opportunity to
learn  how methods of treatment can be improved so that
there  is no threat to the environment. Not only industrial
strength is characteristic of our nations, but also the need to
give world leadership in industrial environmental control.

U.S.  Municipal Wastewater Treatment
Systems

  On the part of the United States, we have embarked on
 one of the largest public works programs in the history of
the world  in order to bring our waters up to fishable and
swimmable standards by  1983. This endeavor involves
 18,000 municipalities with a combined population of over
200 million people. Our Congress has  provided $18 billion
 in grants to municipalities in order to initiate the clean-up
 program. With this $18 billion, which represents 75% of the
 total construction cost of $24 billion,  9,000 municipalities
 will have established their sewerage systems  by next year.
 However, less than 40 percent of the 1977 population will be
 served  by secondary  treatment or  some  higher level
 necessary  to  meet water quality, principally because  the
 large cities will not have had time to complete construction.
 We still have a long way to go, and it will require additional
 large  sums of money to accomplish  our goal. Already,
 however,  we have 7,126 active  projects underway, with
 10,500 slated for next year.
  One  of our  principal  tasks has   been  to  keep  the
 municipalities  enthusiastic and  moving on the program of
 cleaning up their waters. We have found it necessary to have
 seminars, briefings, and conferences that bring the message
 to every potential community  that is eligible for Federal
 assistance. This endeavor has worked  remarkably well and
 has enabled national goals and  standards to be integrated
 into local government aims and needs. We are pleased by
 the progress  that has been made in this area and  the
 cooperation that has been fostered.
U.S. Industrial Wastewater  Treatment
Systems

  Environmental concerns have also been integrated into
the decision-making process in industry.  Many industries
have actually  found it more profitable  to operate with
environmental concerns  in  mind  and  to  recycle  and
conserve water used  in their  processes  and  to  recover
valuable resources from wastewaters. Together government
and  industry expended about  $15.7 billion in pollution
control last year and a goodly portion of this amount was in
control of wastewaters. Of special note is the fact that a new
pollution control industry has been created which employs
some one million workers.
  Of course, our  municipalities are also involved with
treating  industrial wastes, just as  Soviet industry  and
municipalities  cooperate in combined treatment systems.
Our working group has made  significant contribution to
making knowledge known about how  pretreatment of
industrial wastes can be accomplished so that municipal
systems can operate efficiently in treating the remaining in-
dustrial wastewaters.

First  Working Group  Symposium

  I would  now like to comment on  the progress that has
been made by the Working Group on the Prevention of
Water Pollution from municipal and industrial sources.
  Our   first cooperative  U.S./U.S.S.R.  symposium  on
municipal  and  industrial wastewater  sludge,  held in
Moscow in 1975, was a fundamental contribution to ways
of handling the increasing amounts of sludge that are being
generated by our improved wastewater treatment methods.
  Depending  upon  the  composition of  a   wastewater
treatment plant's  sludge, the  quantity involved, and the
disposal method, disposal of sludge can have an important
impact  on  the environment. It is therefore essential for
wastewater treatment installations to consider  the proper
disposal of the sludge that is produced. In fact, this is one of
the most important factors that must be considered in the
design  of any wastewater treatment facility.
  Our insight in making sludge the first topic of our series
of symposia was a  fortunate one. Time has proven that the
method of disposal of sludge  is both  a  problem and an
opportunity. As our symposium indicated, the ultimate use
of sludge as a valuable resource for many worthwhile uses
has to be the ultimate goal of cur efforts. I believe that we
have made  significant progress in the last year. In fact, EPA
has established a sludge Task Force which is just about to
issue its report on developments in this area and the first
symposium provided excellent background material for its
efforts.

Second Working Group Symposium

  Our joint symposium last year at Cincinnati, Ohio exam-
ined physical/ chemical  treatment of  wastewaters from
municipal and industrial sources. It is  here that we are at the
cutting  edge  of  research  and  innovative methods in
wastewater  treatment. The  methods discussed  at the
symposium are  essential tools with which to work to
provide the most cost-effective treatment of difficult wastes
while at the  same time providing  the  means  to  make

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possible the recycling and re-use of water resources. More
and more, our water resources are becoming scarce relative
to uses that have to be made of them. There is, of course, a
definite  limit to  the amounts of water that are available
from  nature. Our only means  of meeting  the need  for
increased  use is  through  conservation and re-use.  The
physical/chemical treatment methods offer us unparalleled
opportunities for re-use, as set forth at our symposiums. We
can be sure that that symposium will always be a landmark
in  progress  in  treating  wastewaters,  if  only  for  its
contributions to  the science  of re-use. But, of course, the
symposium was significant  in a multitude of  other areas of
scientific advance in wastewater treatment. The symposium
papers will need to  continue  to  be mined for valuable
insights, data, and practical applications.

Third  Working Group Symposium

  Our third symposium, which we have convened today, on
"Intensification  of  Bio-Chemical Treatment  of Waste-
waters", is another building block to the success of the
mutual efforts of our nations in bio-chemical methods of
treatment.  Treatment methods are beginning to show
important advances and are a key to many difficult cases of
treatment  needed.
  It is especially notable here that a paper will be presented
from  each  of  four  related  industry  groups: chemical
technology; pulp and  paper;  femorous metallurgy  and
petroleum  refining;  and  petro-chemical.  In  addition,
municipal treatment  processes will be  discussed that  use
bio-chemical treatment. These industrial groups represent a
great  percent of the total wastewater flows to be treated by
industry. As such, we are really covering the  problems and
opportunities of almost all of the industrial flows that must
be considered. Therefore,  we can make real advances in
exchanging  knowledge  of  bio-chemical, methods  and
processes for treating industrial and municipal wastewaters.
I wish you great success in your efforts.

Fourth Working  Group Symposium

  I look forward to our fourth working group symposium
which will be convened in January 1977, again at the EPA
Cincinnati research complex. The subject of the symposium
will be  Physical-Mechanical Wastewater Treatment." This
subject area will continue to round out our efforts to have a
comprehensive view of the subject field of municipal and
industrial wastewater treatment methods and opportunities.
Fortunately,  you will be  able to see our  new research
facility at  Cincinnati in full operation. You will remember
that in November of last year it was still being completed
and was unoccupied.  We are happy that we are able to
extend to the working group an invitation to attend  the
second Cincinnati meeting.

Conclusion

  My review of the accomplishments of the symposia and
visit to the municipal and industrial treatment  works of
both  our countries, leads me to conclude my remarks by
expressing a certain amount of amazement that we have
been able to  progress  so far in a relatively brief time.  We
have approached our mission in a spirit of cooperation and
creativeness.  We have tackled first things first and have
made headway by our industrious and inspired efforts. We
have  more than fulfilled  the  assignment that was placed
upon us, yet there is further progress that we can mutually
undertake. I congratulate  you on all of your efforts and
results.  Let us now move forward even more in improving
our own and the world's environment.

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Kinetics  of Biochemical

Oxidation

by Yakovlev S.V., Skirdov I.V., Rogovskaya
C.I.  and Shvetsov  V.N.
All-Union  Scientific   Research   Institutes
VODGEO

  In the near  future biological methods will continue  to
play the principal role  in the main body  of  wastewater
treatment technology due to a number of advantages the
biological treatment has as  compared  to  the physical-
chemical methods known.
  It should  be  noted  however that  the biochemical
treatment method has not yet. exhausted its abilities.
  At present the improvement of the process by means of it
being affected  by external factors is considered to be the
most practicable.
  Methods of the biological  treatment process improve-
ment in aeration tanks by increasing either concentration of
activated  sludge  microorganisms  or  dissolved  oxygen
concentration (or its partial pressure) as well as increasing
the substrate concentration in first stages of  the process
carried  on in  plug-flow aeration tanks have become a
practice in sanitary  engineering.
  The potential abilities  of this method may be revealed in
full measure during the studies of the process kinetics taking
into account interrelation of the main factors.
  In the cells of microorganisms of activated sludge, which
is the main agent of  the biochemical treatment process,
many enzyme-catalysed reactions occur simultaneously, the
enzymes being closely linked together thus forming complex
polyenzymic systems. The peculiarity of biological enzymat-
ic systems is their ability to self-regulation.
  Having the  data about the  principles  of such  self-
regulation it is possible to simplify the complex chains  of
biochemical reactions essentially.
  Under stationary  conditions the amount of the material
passing through  each  separate stage of the process must
be the same, so the  rates of each separate reaction must  be
equal too. Under these conditions the rate of  the process
will depend on the rate of the slowest reaction. This concept
developed by lerusalimsky  (1) was called "the minimum
principle." It is postulated  in  it that "the rate  of the total
process depends  upon the rate change in the slowest stage
only" while the  rate increase in the other stages doesn't
affect the process. The minimum principle explains such
peculiarities of enzymatic systems as their low conversion
and saturation.  In stationary conditions  the minimum
principle allows to follow only key reactions without taking
into account many secondary ones.
  As  distinct  from non-enzymic reactions the enzyme-
catalyzed reaction rate increases with  a gradual slowing-
down rather than proportionally to the substrate concentra-
tion increase and reaches a certain maximum, the value  of
which depends on the enzyme concentration.
  Kinetics  of  the enzymatic reactions is  based on the
assumption that there is some enzyme-substrate complex
and that  the  reaction rate  depends on the  rate of  its
degradation.  The  complex  is  assumed  to  be  formed
instantly, because its concentration is constant and defined
by  thermodynamic  equilibrium  between  the  enzyme,
substrate and this complex.
  Assuming that the completion of an enzymatic reaction is
preceeded  by formation  of enzyme-substrate  complex
Nichaelis and Menten (2) presented it by the following
scheme
                     "1,
+ E  4 _ SE
      K-l
                                   P + E
and thus obtained the well-known Equation
                       V    + S
                 V =   vmax   a
                                   (1)
where V is the reaction rate at substrate concentration S;
  V     maximum reaction  rate without  substrate limit-
         ing;
  Ks    reaction constant.
  In works by Monod (3) and lerusalimsky (1) the biomass
growth  rate  (A)  was shown  to  be described by the
analogous equation:
where/^ =  dtx ; * is the microorganisms concentration.
  The  relationship  between substrate  uptake rate  and
biomass growth rate is usually expressed by the depend-
ence :
                  dx   =-y   ds
                  dt         dt
where  y  is  the  proportionality factor,  characterizing
biomass yield per unit of the substrate consumed (economic
coefficient).
  Keeping  in  view  dependence 2, the  equation  for the
substrate uptake rate can be written in the form:
                ds  =   1   mavS

                dt    y
                                 x.
                                   (4)
  This equation and  its modifications were successfully
used by Hinshelwood, Herbert, Dawning, Benedek, Gunter
et al (4, 5, 6, 7, 8) in mathematical models of biological
wastewater treatment systems.
  A number of investigators stick to different, fully empiric
dependences, based  on  so-called  two-phase theory of
substrate removal, proposed by Garret and Sawer (9). This
theory was used later by Eckenfelder, McCabe, Korolkov
and Bazyakina (10, 11, 12).
  In accordance with  this theory  and on  the  basis of
experimental data the process of activated sludge microor-
ganisms growth  can be  conditionally divided into  two
phases: in the first one the substrate concentration exceeds
the limit, necessary for the complete saturation of enzymic
systems, in the second one the saturation rate decreases as
the substrate is removed.

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  For  the  first phase  the following type of Equation is
assumed:
                     dx_ -  KjX                   (5)
                     dt
and for the second one
                   &L  = a • K',x • S,              (6)
                   dt
where a is an empiric coefficient and coefficients K^ and X
are combined:

K'2x =  K2.
  In a transition point of these two phases where the growth
rates are equal according to Equations S and 6 Kix = afeS.
  The further development of this theory by Wuhrman et al
(13) as applied to the multicomponent substrates has led to
the hypothesis according to which the waste water substrate
removal curve is the superposition of direct line  segments
characterizing uptake of a particular substrate compounds
by activated sludge. •
  With the help of this hypothesis a satisfactory agreement
of the  calculated  data  with the experimental ones can be
obtained as shown by the work of Evilevitch et al (14).
   It should be noted however that the use  of theoretical
regularities known in modern biochemistry and microbiol-
ogy  gives  more  possibilities  for  the  mechanism of the
biological treatment process to be revealed as compared to
empiric formulae which have a particular character. It must
be born in mind that either for a single cell or for a complex
biocoenosis of activated sludge oxidizing multicomponent
substrate the minimum principle is apparently valid, that is
the limiting of the process by one, the most slow reaction.
   Information obtained from the literature can't give a clear
unambiguous answer to the question about the character of
the relationship  between the MLVSS  and the  rate of
organic matter oxidation in aeration tanks.
   A number of recent investigations (15,16) show that there
is no proportional relationship between the MLVSS and the
rate  of oxidation;  sludge activity measurably  decreases
when its concentration increases. Analogous phenomenon
is observed during the  propagation of living  organisms
population in the process of biological synthesis as well. In
general this phenomenon can be caused by the  following
reasons:
   — the mass exchange deterioration due to the  change in
reological properties of mixed liquor;
   — interspecied  competition of microorganisms;
   —microorganisms development suppression by products
of their metabolism.
   The  lack of information referring to the  effect of the
MLVSS  concentration  upon  the rate  of biochemical
oxidation does not permit drawing a conclusion  about the
mechanism of this phenomenon.
   It should be noted that there is no agreement in the
works devoted to the dissolved oxygen concentration effect
upon the activated sludge microorganisms metabolism, and
the experimental results are very contradictory. Some
investigators  point  out to the existence of the  dissolved
oxygen critical concentration above which the oxygen effect
on the process is not observed (17,18, 19). Concrete values
of this concentration according to the data obtained by
different investigators have  an  essential error.  In other
works  mainly  referring to  the enzymes production,  a
suppressive or toxic effect of high D.O. concentrations was
observed (20, 21). In a number of recent works dealing with
the problem of oxygen use for biological treatment (22, 23)
an evident positive effect of the oxygen concentration up to
30  mg/1 was marked. In  this case  the rate of substrate
removal  increases and the settling  properties of  mixed
liquors is being improved.
  Disagreements  in the evaluation of oxygen  effect upon
the biological treatment  process can  be explained by the
influence of  many secondary factors badly affecting the
experimental results, by the insufficient variation  range of
the parameters under study and by the absence of uniform
methods and suitable equipment for such  investigations.
  It should  be outlined especially   that  the theoretical
aspects of D.O. and MLVSS  concentrations effect on the
kinetics of  the  biological  treatment process have been
studied insufficiently.
  It is known from biochemistry that the molecular oxygen
can be involved in the cellular metabolism in three  ways:
  1. as a terminal electrone  acceptor in the respiration
chain;
  2. at  the  direct incorporation  into the substrate to be
oxidized;
  3. for direct acceptance of hydrogen from dehydrogenases
with the hydrogen peroxide formation, without respiration
chain being  involved.
  The molecular  oxygen role in the cellular metabolism is
extremely great, because it is one of the  most important
components of the processes providing the microorganisms
with the energy and material for their biosynthesis.
  The molecular oxygen does not only take part in the final
substrate  oxidation  but  oxygenates a large  number of
organic compounds in the initial stages of their metabolism,
and thus enables  their being used by microorganisms.
  Due to the conjugation of oxidation and phosphorilizing
oxygen  influences on  the energetic  level practically all
enzyme-catalyzed  processes proceeding in the cell. On this
basis  one can assume that the oxygen  effect must be
described  mathematically   by equations  of  enzymatic
reactions. Since the substrate and oxygen  take part  in the
oxidation process, this  equation must  be  one of the
bisubstrate enzymatic reaction equations the type of which
may be determined after the analysis of experimental data.
  The attention of investigators in the field of wastewater
treatment is especially attracted by the theoretical aspects of
the regularity between biochemical oxidation of organic
compounds  and their physico-chemical structure, kinetics
of its biochemical destruction  and enzymatic properties of
the microorganisms involved in the process.
  When studying the effect of the material structure on the
biochemical destruction process Winter (29) has drawn a
conclusion that in most  instances the rate of destruction
decreases as the molecular weight increases. The oxidation
rate decrease was observed in the homologous series of
alcohols  with lengthening of hydrocarbon chains. By the
author's  opinion the  chain  branching  decreases  the
oxidation rate essentially. It  is  valid,  however, for the
aliphatic series only.
  An unimportant change in  the structural formula of a
substance produces  a considerable  effect on biological
oxidation.  Substances with the hydroxide  radical are
oxidized readily.
  When studying  the effect of various functional groups on

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the rate of the organic compounds destruction Winter
marks the continuous decrease in the rate of the biological
degradation involving the following succession: — SO2H,
— OH, —COOH,  —NH2, —CN, —CHOH,  — CH,OH,
—OOC, —CH2, —CH3.
  Among the aromatic compounds  benzene is the  least
biodegradeable; compounds with a short side chain such as
toluene  and ethylen benzene are a little more biodegradable.
Compounds  with  longer side  chain  inhibit  biological
destruction almost completely.
  The information  available gives only approximate data
concerning the effect the molecular structure of substances
produces on their biochemical oxidation parameters.
  In the majority of the well-known works (30, 31) the
quantitative evaluations are  absent, many of the data are
contradictory since the investigations were  conducted in
different conditions and under different methods. Criteria for
the experimental data evaluation various as well.
  These circumstances caused the  necessity  for  special
complex investigations to be conducted  including techno-
logical,  miclobiological and oxidation process  of organics
belonging to different classes.

Methods  of Investigations

  It was shown previously that the metabolic activity of the
microorganisms depends on the external parameters and
first of all on the concentration of a  carbon substrate and
D.O. concentration.
  The lack of only one component in the environment causes
decrease in the metabolic activity, that is why investigation of
the external parameters affect the so-called "limited" media
are usually used, where the amount of only one component
under investigation is varied and the  other components
necessary for the cell growth are present in excess.
  In modern practice of biological studies in general and
studies  of kinetics  of wastewater  organics  biochemical
oxidation ' in particular, two  approaches  are  used: the
continuous cultivation method and the method of investiga-
tions  in batch  conditions, each of them having its own
advantages and shortcomings.
  On the basis of the properties of the  subject under
investigation and  the aims of investigations a method must
be chosen capable of providing the maximum reliable
information with the minimum of efforts and expenditures
spent.
  Activated sludge has a number of specific properties the
most  important of which are its biological inertia and
adaptation.
  Biological  adaptation  of activated  sludge  is such  a
phenomenon when  the cell  gradually rather than imme-
diately adopts to the environmental change. Increase in the
cell growth rate is connected with the preliminary increase
in the amount of ribosomes and other organelles responsi-
ble for protein  synthesis. The process takes  the  time
comparable to the time for cell reproduction.
  Adaptation of microorganisms to the particular environ-
mental conditions is connected with the reformation of the
cell enzymatic apparatus as well as the change in the specied
composition of the  activated sludge as a result of natural
selection and mutation. When environmental conditions are
changed adaptation  causes  corresponding  changes  in
biochemical properties of the culture.
  When  evaluating  the microorganisms  properties one
should bear in mind that the substrate biological destruc-
tion  is carried out by enzymatic reactions  the duration of
which amounts to seconds.
  As compared to the synthesis reactions  of  enzymatic
macromolecules  or to the processes of the cell working
apparatus formation  (ribosomes, mitochondrions,  mem-
branes) the duration of which amounts to hours enzymatic
reactions may be considered very rapid ones.
  Comparing the continuous- and  batch-flow methods it
should be  mentioned that in  the closed system of batch
studies simultaneous change of several parameters with time
(substrate,  oxygen, metabolite and biomass concentrations
etc.)  is inevitable. This makes the evaluation of some
parameters  under investigation difficult.  Besides,  the
phenomenon of biological  inertia can sharply reveal itself
here.
  The continuous-flow cultivation method does not possess
the above  mentioned disadvantages of the batch method
because it theoretically allows to keep the biological system
studied in the given equilibrium state for unlimited period
of time.  However when  the  continuous-flow  process  is
carried on in practice serious technical difficulties can occur,
breaking its stability and  lowering its  accuracy  and the
reliability of experimental data. These difficulties are caused
by the necessity for the microamounts of substrate elements
to be dosed precisely as well as the necessity for stabilization
of biomass concentration, pH, aeration  intensity  or  O2
concentration etc. Any reliable control devices for many of
these parameters have not  been available yet.
  On the other hand the change of external parameters in a
continuous-flow reactor ineritably leads to adaptation and
so to the chape in biochemical properties of activated sludge
that interferes with the analysis of the external factors affect
on biochemical properties of activated sludge that is upon
its enzymatic apparatus.
  Thus none of the accepted methods can pretend to be the
universal one, each of them has  its own field of application.
  The continuous cultivation  method is expedient to  be
used for the growth of activated sludge biomass adopted to
a certain substrate. This method is irreplaceable for the study
of slow adaptation processes.
  When  the effect of the  external parameters upon the
sludge enzymatic activity  is studied  the  batch tests  are
rationaly used.
  In batch  tests the right choice of the interval in which the
process rates are measured is of great importance. It must
be small enough in order for the substrate  and activated
sludge not to take the time to alter significantly  and the
metabolite  concentration not to reach a noticeable value.
Besides, this interval must be large enough in order for the
equilibrium of the system, that is a quasi-stationary state of
kinetic parameters, to be reached.
  On the basis  of general considerations concerning  the
methods  of investigations into the kinetics of biochemical
oxidation the bench-scale studies  were carried  out on
continuous-flow  models of  aeration  tanks of  various
modifications as well as by  means of running "sharp" tests
in batch-flow aeration tanks and respirometers.
  In continuous-flow  conditions the experiments were run
for  comparison  of  D.O.  concentration  and  MLVSS
concentration effect upon the biochemical oxidation rate
for various substrates. The necessity for these experiments

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  to be run was dictated by the desire to bring the results of
  bench-scale studies close to full-scale conditions since they
  allow to take account of the activated sludge adaptation to
  certain  substrates  and to other external conditions which
  can take an important effect on the sludge activity and on its
  physical characteristics,  in  particular upon  the settling
  properties.
   During investigations a regular technological control for
  the operation  of the units was  carried on. The microbial
  content of activated sludges, its physical parameters (such
  as sludge volume  index (SVI), the size and  the form of
  zoogloen), ash content, COD and BOD of the effluent and
  mixed liquor, MLSS,  N, and P content of the effluent were
  determined. Chemical analyses were conducted by Standard
  Methods.

 A Complete-mixing Aeration Tank

   A  conventional  laboratory aeration tank served as a
 model  of  the  complete-mixing aeration tank  (Fig.  I).
 Aeration tanks for operation with high MLSS concentra-
 tions were  rigidly fixed with the settling tanks.
   Sludge recirculation was carried on either by a dosing
 diaphragm pump  or   at  the expense of the  difference
 between volume weights of air-water mixture.
   The control  for  air  supply was carried on manually in
 accordance  with the   given oxygen  profile.  The D.O.
 concentration was  determined periodically by an electro-
 chemical sensor.

 A Counter-flow Aeration  Tank

   For determination of the counter-flow efficiency in the
 process of oxygen absorption and its uptake by biochemical
 oxidation the model of a counter-flow aeration tank was
 used.
   The counter-flow aeration tank operated in the regime of
 a complete-mixing reactor; it was a closed circuit compris-
 ing two vertical columns made of plexiglass (Fig, 2).
   Recirculation of the liquid in the circuit was created by an
 impeller pump (I) fixed  in the upper part of the recirculation
 column  (2). This  permits the  necessary  rates of  the
 downflow in the aeration  zone to be obtained (column 3).
 The rate of recirculation was measured by the head loss in
 the measuring diaphtagm (5) and was regulated by a valve
 (6). Influent was fed to the aeration tank through the tubing
 (7) in the upper part of the aeration column. Either oxygen
 or air was fed through  the porous diffuser (4) in the lower
 part of aeration zone.
  The oxygen profile stabilization was fulfilled by automati-
zation of the air supply system on the  basis  of D.O.
analyser.  This  system   provided  the  accuracy  of  D.O.
concentration ±1.0 mg Off 1 in the range of this parameter
change from 3 to 20 mg/1.
 dozing pump
                                                  effluent
           influent
                    °f * laboratory «>n«Pl«t« mixing aeration
 Respirometers
   The large part of experimental data was obtained as a
 result of investigations conducted on respirometers.
   The experiments were run in order to obtain kinetic
 constants  for  equation  of enzymatic  reaction  during
 investigation of  the  effect, the' substrate,  oxygen and
 activated sludge microorganisms concentrations have upon
 the process.
   The respirometric method is  widely used  in biological
 studies of such processes accompanied by gas-exchange as
 plant 'photosynthesis, metabolism in tissues and respiration
 of microorganisms.
   The advantage of respirometric methods are their relative
 simplicity and ability of making direct volumetric determi-
 nations of the oxygen consumed as well as the continuous
 observations with the automatic recording of the data.
   Negligible inertia allows to work with the small amounts
 of substrate.
   The possibility of simultaneous gas-exchange analysis on
 the basis of oxygen uptake and carbon dioxide release
 places the respirometric method in a special position even as
compared to such  modern  methods of investigations  as
polarography and CO2 analysis with the help of experimen-

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tal acoustic analysers.
   Warburg manometric instruments were practiced on a
large scale for respirometric studies, but they have a number
of serious disadvantages such as a small volume of cultural
vessels,  the  impossibility  to  control  during  study  the
following process parameters (oxygen profile, pH, substrate
composition and concentration).

                             sludge separator

                                      £
                                              effluent
                                              (to the
                                              darifier)
                                           dosing pump
                                           for sludge
                                           recirculation
dozing pump for
excess sludge
removal
    differential i
    manometer
Figure 2 The scheme of a laboratory counter-flow
  Automatic manometric  instruments  -  respirometers -
have  been  used  recently. They differ  from  Warburg
respirometers by large volume of cultural vessels, intensive
agitation, aeration of tne culture and forced absorption of
the carbon dioxide released.
  In the laboratory of biological treatment a continuous-
flow respirometer was developed,  the scheme of which is
given in Figure 3,
  The  respirometer consists  of the  following principal
units:
  I. The unit of microorganisms cultivation consisting of
three hermetic vessels with impeller aerators;
  II. The unit of automatic  oxygen supply  with wet
gasholders;
  III.  The  unit  of automatic  recording  of the oxygen
consumed;
  IV.  The  unit  for carbon  dioxide  removal  from  gas
mixture with mic/ocompressors and scrubbers;
   V.  The  unit of temperature  stabilization with contact
thermometers;
   VI. The unit of D.O. concentration measurement with the
help of D.O. andlysers "   -152.003".
   VII. Sludge separation  unit with vertical  settling tanks;
   VIII. System of sludge feeding  and recirculation with
plunger pumps;
   IX. pH stabilization system;
   X.  MLVSS stabilization system.
   The respirometer was  provided  with three  fermenters
each  of them equipped  by autonomous  systems of air
supply, gas purification, temperature stabilization etc. This
allows to conduct parallel investigations in a wide range of
parameters change as well as technological researches of
multi-stage systems of wastewater treatment.
   The instrument has the following technical characteris-
tics:
                                                              VIII

                                           VII
Figure 3 Technological scheme of respirometer

  I.   The fermenter capacity is 3 1.
  2.   The oxygen feeding accuracy 0.4-0.8 cm'
  3.   One scale division of the consumed oxygen recorder -
      6mg/l.

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 4.   Accuracy of the consumed oxygen registration is 1.5
     mg/1.
 5.   The  system of  D.O.  concentration recording is
     automatic. The accuracy  of recording is ±0.5 mg/1
     when the instrument of the type   -152.003 is used.
     Variation  range of D.O. concentration  is  0.5-20
     mg/1.
 6.   The system of control for the carbon dioxide released
     (potentiometric titration with Ba(OH)2 is manual or
     automatic. The accuracy of CO2 control is 2  mg/1.
 7.   Agitation and aeration is carried on with the help of
     an impeller  having 6-step  reducer  with  200-1500
     rev/ min.
 8.   The system of temperature stabilization with heating
     and cooling is  automatic.  The accuracy of stabiliza-
     tion is ±0.25° C. The temperature variation range is
     +5 - +40° C.
 9.   Feeding of the substrate  is carried on  by plunger
     pumps  with  a  continuous change from 0.01  to 10
     cm3/min. The accuracy of feeding is  ±5%.
 10.  Sludge  recirculation is carried on by plunger pumps
     with continuous change in discharge from 0.01 to 10
     cm3/min. The accuracy of feeding is 5%.
  Finishing the description of the methods of experiments
for  biochemical  oxidation kinetics  determination one
should mention a very important peculiarity of biological
systems  and  of activated sludge  in  particular.  This
peculiarity is the poor reproducibility of the  experimental
data.  It  is  caused  by two factors: by inaccuracy  of
instruments and to a large extent by their poor reproducibil-
ity (or by so-called time drift) which depends on biochemical
properties of activated sludge.
  The dispersion of the results caused by the  time drift
usually exceeds by  the order the dispersion  caused by
inaccuracy of measurements. Relatively law efficiency  of
strictly successive methods  of  the experiment planning  at
the researches of biochemical systems may be explained by
this  fact.
  In order to control disagreement of the results caused by
time drift it is appropriate to  carry on the experiment  in
such  a  way  that  all  values  of the parameter under
investigation could  be studied  in one run. Very  often it is
not  possible to do; then several series of tests should be
conducted, but in each series one test from the proceeding
one should be repeated.  On the basis of the test repeated it
will  be possible to  determine the disagreement caused by
time drift.

Discussion of the  Experimental Results

A.   THE SUBSTRATE CONCENTRATION EFFECT
  The dependence  of the biochemical oxidation  process
rate on the substrate concentration was studied in continu-
ous-flow conditions  on models of complete-mixing aeration
tanks and in batch-flow conditions on respirometers,
  Such pure chemicals as acetone, normal propyl alcohol,
isopropyl alcohol, propionic aldehyde and propylenglycol
etc. and real industrial wastewaters of yeast and antibiotics
production  were  used  as  substrates  (as the sources of
organic carbon).
  In accordance with the working hypothesis the substrate
concentration effect  on the specific reaction rate is described
by  the  equation  of enzymatic reactions (4) the  kinetic
constants of which may be determined graphoanalytically
by Lineweaver - Berk method according to which the initial
Equation 4 is presented as reciprocal values
              _L =    1   +   Ks
              V
                     'max
vmax  ^
                                                  (5)
                _1_ J_
  In coordinates V ; S the graphical form of this equation
is a straight line intersecting the axis J_ in a point of   1
             1                  1   V            V
and the axis — in the point of—.                max
             S               Ks
  The experimental data plotted  to this graph have shown
that straight  lines have different angles  of inclination for
different series of tests but intersect in one point (_L_). It
                                             -Ks
points out to  the fact that one of the reaction components is
not homogenous,  which is caused by  the time  drift  of
activated sludge.
  The existence of the common point of intersection shows
that the change of the sludge enzymatic activity affects the
function V =  f(S) in accordance with the law of noncompe-
tent modification, the equation of which  has the form:
             V = V
                       f _Kj_\   s
                  maxl 	 I	
                       M + K. /K.+
                              1    3
                                                   (6)
 where K, - kinetic constant of the modificator;
      I  - modificator concentration.
   In reciprocal values the equation can be presented as
                                                    (7)
          'max
  It follows from the graphical form of the Equation 7 that
the relative activity of sludges for each series of tests differs
by the multiplier (       ) and may be evaluated through
the ratio of maximum values
              L =
                   1/Vj
                           =  VcPmax
                   1/V,
                                                  (8)
                      max
                                'max
where L   - sludge activity coefficient for the given series
             of tests.
  VcPmax "  meiinvalueofvmax
  vlmax  -  valueofvmax for the 8iven series of tests.
  Values of specific  rates with correction for the sludge
activity time drift may be defined as
                     V'= V,  d,,                  (91

where Vj is a reduced value of Vmax for the given series of
tests.
  The  corrected values of oxygen  uptake rates and  the

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initial  data  for  their calculation are given in Fig. 4. It
follows from the graph that
      max
           = 99.4mgO2/g of VSS/hour.
I
'.',
1.0
     Ks= 152 mg/1

  The  terminal form of the function V=f(S) for acetone,
oxidized by the activated sludge, is given in the Fig. 5 where
the points, obtained by the calculation in accordance with the
equation 4, are connected by a curve.
  The  corrected values of the experimental data agree with
the calculated curve, their maximum deviation does not
exceed 5 percent.
  It  should  be noted that without  time drift these ratios
reached 213%.
  Analysis of the  graphical forms of the function V=f(S)
(Fig. 4) shows that  curves have  smooth slopes  with the
asymptotic approaching to V max, consequently the approx-
imating of this curve by the two straight lines is wrong from
the theoretical point of view.
                                                      !
     -L
     If:
Figure 4 Determination of kinetic constants by Lineweaver-Berk
method
;
0i
j.






t

[




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,.



•-















— ^




















oa 2>
























o»
















3



ir(-/ff/-

































•* V








V,'
-t







„., »f/,w
•Xft^t





















•— • —





-------
be proved.
  The biomass growth rate in the Ferhulst equation may be
expressed through the specific oxidation rate:

               .dx. =    1         .x            (11)
                dt       y       n
(the designations are the same).

  The specific oxidation rate for a particular kind of sludge
at x = 1  g/1  and other  conditions being invariable is the
constant, that is    i= E.                            (12)
With consideration of Equations 11 and 12 Equation 10 is
reduced to the following form:
                     JL  =  L (
                       1        E
x)
   Introducing designations for constant coefficients

                 V.    =Aand     X.  = B
                 E                  E
 we obtain
                        = A -
          (13)
   Expression 13 is  the direct  line equation, that doesn't
 correspond to the experimental data, given in the plot (Fig.

   Hence,  the Ferhulst equation can't  be applied to  the
 activated sludge biocoenoses.
   As  previously mentioned the  decrease  m  the sludge
 activity may be caused  by the products of metabolism
 release, inhibiting  biochemical oxidation process which
 mechanism is described by the following equation
            V =
                                                   (14)
 where the inhibitor concentration according to lerusahmsky
 (26) is proportional to the  amount of microorganism
 biomass.
                        1=
                                                   (15)
   The rest designations are the same.
   In Equation (14)  in conditions  of constant  substrate
 concentration or its excess (in these particular conditions a
 comparison  should be made) the members characterizing
 the substrate effect may be expressed by a constant
                                 = A
           (16)
   The specific oxidation rate at x = 1 g/1 for a particular
 substrate may be considered a constant as well.

                         V. = E                     (17)
                                                            Then the Equation will assume the form:
                                    V = A
                                                 Ki
                                                (18)
                                              Zx
                      The rates ratio with consideration  of the assumptions
                    made may be expressed as follows:
                                    V_
                                    Vi
                            AKi
                         E(Zx + Ki)
                                                  (19)
                      For  the graphical interpretation it  is  convenient to
                    present the Equation obtained (19)  in the form:
                                                -v
                                                K. )
                                       \_
                                      A
(20)
                      For a concrete substrate the Z/Ki ratio is a constant.
                      So we  can  assume  that  Z/Ki =     where  Y  is the
                    coefficient  characteristic  inhibiting  of the  process  by
                    products of metabolism.
                      Then Equation 20 may be  written in the following form
                                                                                                               (21)
                                                                                                         • = f(x) are
  As can be seen from Fig. 7 the curves for
the straight lines.                          v
  This facts serves as the proof of the applicability of bility.
  The angle of inclination tangent gives the value of
Equation  14.
  Analysing the  position of direct  lines  for different
substrate concentrations one can note that tg  decreases as
S increases to a certain value. Hence for determination of
coefficient   it is necessary to use the data obtained without
limiting by substrate.
  The specific  rate value corresponding to the intersection
of direct  lines in the plot  of 1 = f(x) with the ordinate
                              V
axis (^corresponds to the rate A without  inhibiting by
     V
metabolites.
  Thus the analysis of experimental data has shown that the
sludge activity decreasing with the increase of its concentra-
tion is described by the enzymatic reaction equation with
consideration of non-competente inhibiting by metabolites.
  It should be noted that inhibiting in a certain range of
MLVSS variation is less than the increase in the total sludge
biomass activity, so with the  MLVSS increase the essential
increase in the oxidation capacity of aeration tanks occurs.
For certain substrates the dependences of oxidizing capacity
on MLVSS is  given in the plots (Fig. 8). Optimal value of
MLVSS (from the oxidizing  capacity point of view) varies
in the range from    to    g/1 and depends on the constants
of  the enzymic  reaction equation, characterized by  the
individual properties of the substrates.

C.  EFFECT OF  D.O. CONCENTRATION
   Technological studies on the models  of aeration tanks for
investigation of D.O. effect  on the biochemical treatment
process were carried on with the acetone and phenol used as
                                                         11

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  substrates.
    Operation data of counter-flow aeration tanks when the
  air is fed to one of them and the oxygen to the other one, are
  given in Table 1 .
    There is a  significant increase  in  the process rate  as
  the D.O. concentration increases. Thus the acetone specific
  oxidation rate increased from 3.4 to 1 12 mg/l/h (2.88 times)
  as the D.O. concentration increased from 3 to  12.7 mg/1.
    Similar  data were obtained  in tests conducted in batch
  flow aeration tanks.
               .t
              V'rff*
                   7f
               I
               *^r<
 Figure  7 Graphical  form of 1/V = f(x)  for determination of
 inhibition factor Y at oxidation of acetone (1) secondary octyl
 alcohol (2) and isobutyl alcohol (3).
      on
                         >
                      10
                             If
                                    &
                                          -Jtf
                                                 30
 Figure 8 Relative change in oxidizing capacity with the MLVSS
 increase in aeration tanks at oxidation of acetone (1), octyl alcohol
 (2) and pyrocatechol (3).
      -le
Figure 9 Graphic of binary reciprocal values of the relationship
between oxygen uptake rate and its concentration.
J. substrate concentration of 94 mg/1
2. Substrate concentration  of 360 mg/1
3. substrate concentration of 450 mg/1
   A  wide  cycle  of  experiments  was  carried  out  on
 respirometers in batch  conditions  for  a more accurate
 quantitative  evaluation of the D.O. effect. These  experi-
 ments were carried on with substrate (acetone) concentra-
 tion varying from 0.5 to 33 mg/1 and oxygen concentration
 varying from 1.0 to  20 mg/1.
   The experimental  data are given in the plots of functions
 of V = f(Co). (Fig. 9).
   The plots of reciprocal values  in coordinates 1/V - 1/S
 were used for identifying the mechanism  of D.O. effect.
   It was noted in a number of recent works (27, 28) that the
 process  of  oxygen  and  substrate  interaction may be
 described by several  mechanisms. The mechanism of a two
 stage substitution is possible,  where the reduced enzyme
 group reacts with the products of respiration chain.
   The following equation corresponds to this mechanism:
                                                                     •y
                                                                                       S Co
                 maxKsCo
                                                                                          KoS + SCo
                                                    (22)
 where  /dx/dtx-is the specific microorganism growth rate.
           S -  the substrate concentration.
         Co -  partial pressure of oxygen.
  Ks and Ko-  equilibrium constants.
   When  analysing  experimental data  with the  help  of
 reciprocal values plots  a large  dissipation of  points was
 observed  that  can be  explained by the time  drift;  of
 activated sludge properties.
   As  applied to the  two-stage substitution  mechanism
 (Equation 22) the time  drift causes lowering of all points
 obtained  in the given series of experiments in the ordinate
 axis by the same value as to the mean statistic value (Vcp)
 for the given S.
   The  correction for the time drift (at the investigation of
 D.O. effect) was defined as a value by which it is necessary
 to remove the experimental lines along the ordinate axis for
 the given series of experiments so that they pass through the
 points  corresponding to  the  mean statistic values of Vcp.
 that is J}  - Vcp-Vi                                  (23)
   On the basis of this correction a summar plot was made
 (1/V =  f(l/Co) (Fig. 10) with the help of which the values of
 constants  Vmax and Ko  were determined, characterizing
 D.O. concentrations effect at various  substrate  concentra-
 tions.
   A point with the coordinates 1 / Vmax  cp was plotted on this
 graph corresponding to the excess substrate concentration
 (see Fig.  10). A direct  line  parallel  to  the other exper-
 imental lines  passed  through  it.  Intersections  of  this
 direct  line with the coordinate axises give the reciprocal
 values of unknown 1/Ko and I/Vmax.
   For acetone V max = 133 mg O2/g/h and Ko = 2.38 me
 02/1.
  The experimental data analysis (see the plot for V = f(Co)
 in figure 10) has shown their satisfactory agreement with the
 calculation data according to Equation 22.
  A remarkable peculiarity of the dependence obtained is
 the fact that  the greatest effect  of D.O.  concentration  is
 observed in excess substrate concentration conditions. The
 role of Co parameter diminishes as the  value of S decreases.
 Hence the maximum increase in the oxidation rate at the
expense of D.O. concentration increase is possible when
conducting  incomplete  biological treatment or in initial
stages of multi-stage systems.
                                                         12

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  Figure 10 Relationship between  the oxygen uptake rate and its
  convention:
  1 - substrate concentration of  94mg/l (COD)
  2 • substrate concentration of 360 mg/l
  3 - substrate concentration of 450 mg/l
    On  the  basis  of  Equations 21  and 22  a generalized
 dependence may  be obtained
     V = Vmax
                       S -Co
!
                 Ks • S + KCo + SCo  (1+yx)
          (24)
   The equation obtained  considers the effect of the main
 components of biochemical oxidation and is used  by the
 authors in mathematic modelling of the biological  waste-
 water treatment process.
 D. EFFECT OF THE  MATERIAL STRUCTURE ON
 THE BIOCHEMICAL DESTRUCTION PROCESS
   It is rational to analyse the effect of the organics structure
 on parameters of biochemical treatment using conventional
 characteristics of the physico-chemical  properties of the
 matter or  on the basis of  sanitary-chemical analyses. The
 main  data  characterizing  substances  under  study and
 parameters of their  biochemical  oxidation  are given  in
 Table 2. Figure II illustrates the relationship between  BOD,
 COD, specific oxidation rate j> , the sludge yield volume
 and the molecular weight of a number of organics tested.
   The run of BOD and  COD curves (Fig. II) shows that
 these parameters  have the  tendency  to decrease as the
 molecular  weight  grows.  This tendency breaks as the
 structure of the substance changes.
   Analysing mutual position of COD and BOD curves one
 should note that they draw together as the molecular weight
 grows,  that  is the  BOD/COD ratio increases.  Activated
 sludge growth curve  repeats the run of BOD and  COD
 curves  in  general  outline  and  slightly  lowers  as the
 molecular weight of substances grows.
   The   value  of the  BOD/COD  ratio also  gives the
 possibility  for judging about the character of bacterial
 metabolism responsible for oxidation process.
   Catabolic ways of metabolism prevail  at large values of
 this ratio while the anabolic ways prevail at low values. One
can judge about this on the basis of the data given in Table
2,  from which it is seen that energetic processes prevail over
constructive ones at large values of BOD/COD ratio which
is  followed  by low activated sludge yield and  low  total
bacterial number of 1 g of sludge respectively. Constructive
processes prevail in processes with  relatively low BOD-
/COD  ratio.
  Figure 11 Dependences of BOD, COD of substance, the specific
  rate of their oxidation and sludge yield on the molecular weight.

    This relationship is proved by literary data.
    Sharp diminishing of the difference between COD and
  BOD of 1 mg of the substance as     increases claims
  attention.
    This relationship is presented in Figure 12. It must be
  noted that the growth of    with the growth of BOD to
  COD ratio agrees in outline with the ideas formed.
    However, the data about various organics biochemical
  degradeability have not been systematized yet and enable to
  make the comparative qualitative evaluations only. In con-
  nection  with  this more  detailed analysis of relationship
  between  oxidation rate and BOD/ COD ratio is of interest,
  because  the  values  which form it,  are accessible for
  quantitative  determinations  with the  use  of  standard
  methods.
    In Table 2 the data are given about BOD and  COD of
  particular  substances and about specific rates  of their
  >xidation.  In general these data are obtained as a result of
 laboratory   investigations  carried  out  at  the  Institute
 VODGEO.
   Graphical forms of the following functions are construct-
 ed for the analysis of these data :
                                = f (COD-BOD);j> = f
                                                       COD/'
                       M
                            \
                                              to
                                                                   t,t can-too

                                                                      and
rnneRAn I*e'ationsniP betw«n specific oxidation rate
COD-BOD difference
x - according to VODGEO data
  - according to construction norms and laws II. 74.
where C is a specific amount of organic carbon in a tested
substance expressed  in g of C/g of substance.
  It follows from here that despite the essential dissipation
of experimental points  correlation  between  the rate of
oxidation  and  BOD/COD and  COD-BOD values  is
followed rather clearly.
  Statistic analysis of the experimental data was carried on
                                                        13

-------
with the help of a computer "M P-2" and  showed the
following:
                                                      a,o
 1)
= f(COD-BOD) =
                                                  (25)
                          [a(COD-BOD) + B]2
               a = 0.1164    b +0.1427.
  The  root-mean-square  deviation  (dispersion)  of this
function from the majority of experimental points is equal
to 8.9350 mg Oz/g/hour.
  The value of confidence  interval E = 0.2262 at the number
of degrees of freedom K equal to number of points n - 42 is
K=/f-l  =41.
  The value of confidence  of probability   is equal to 0.96
(significance level is 28%).
  2) for the dependence of the type
            COD
                                I
                                                  (26)
               /BOD\
              [aVCOD/ + B]2
      a = 0.002898    b = 0.4421
   The value of confidence interval E = 0.1510. The root-
 mean-square ratio of approximating function

                 6  =11.4548  mg°2
                              g/hour

   Confidence probability P  = 0.87 at the number of point
 equal to 42.
   Thus  for practical evaluations the following dependence
 providing more close correlation of parameters may be
 recommended:
                             I
              /O.I 164 (COD-BOD) + 0.1427/2
                                                   (27)
      The dependence BOD = f(C) (Fig. 13) is described by the
    straight line equation y = ax + b, where y = BOD, a = 4.7579
    b = 1.1894, that is BOD = 4.76 • C -  1.19.
      The total dispersion    = 0.58195.
      The confidence interval value E =  0.3142. Confidence
    probability P = 0.99 at the number of experimental points
    equal to 21.
      Substituting BOD value from Equation 28 into Equation
    27 we shall obtain the  dependence
               0.1164 [COD-(4.76 • C-1.19)] + 0.1427
                                                      (29)
    which allows to  determine the specific oxidation rate
    without the BOD analysis.
                                                   Figure 13 Relationship  between  BOD and dissolved carbon
                                                   concentration.
                                                     While evaluating the accuracy of obtained dependences it
                                                   must be born in mind that the reproducibility of experi-
                                                   ments run for determination of biochemical oxidation rate
                                                   is comparatively  poor;  BOD  and COD values are not
                                                   absolutely accurate either.
                                                     In the experiments run for determination of  specific
                                                   oxidation rate (  ) the deviation  from mean values may
                                                   exceed 50%; in the analysis for BOD total this error varies
                                                   within the limit of ±10%. The COD value is defined more
                                                   accurately but in this case the deviations from mean values
                                                   within the limit ±5% are the most probable. With the ratio
                                                   caused by errors of the experiment and the analysis taken
                                                   into account the  relationship  between COD  and BOD is
                                                   more trustworthy.
                                                     The relationships obtained (27, 28, 29) are valid for pure
                                                   substances  and their applicability to complex  mixtures
                                                   characteristic of  industrial wastewaters  demands further
                                                   development. The methodical approach to the problem still
                                                   demands the further development. Apparently, the results
                                                   of this problem's solution cannot be obtained soon, but for
                                                   practical purposes the use of approximated relationships is
                                                   possible.
                                                     The experimental data analysis  has shown also that the
                                                   correlation  between  V max and  BOD/COD is observed
                                                   (Figure 14). It  is  interesting to note that the experimental
                                                   points formed two straight lines each of them is character-
                                                   ized by the value    COD
                                                         14

-------
     Dependence of constants Ks and    on V max is given in
  the plot (Figure 15). A rather clear dependence of   on V
  max can be seen here, but as far as the constant K is referred
  the tendency for its increase as the V max decreases can be
  marked. This aspect alongside with the relationship between
  the biomass yield and  substrate properties  demands  the
  further researches.
                                         s
                                      y
  Figure 14.Relationship between the maximum oxidation rate Vm
  and BOD/COD ratio.
  1 - at COD/C = 3.6 - 4.1 ;2 - at COD/C = 2.2 - 3.3.



0


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I
•4
/ v>
J
I
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s
s
L-ft,

ff
r^~&
•
\
7^

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2-

i— — ~

	
, /'
#=<-

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•* 	 n
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          m>    MB   *w   v*    tat    Mr   nf

 Figure 15 Relationship between Ks and constants and Vmo.

 Conclusions

   Investigations into biological treatment kinetics carried
 out under laboratory conditions drew the following conclu-
 sions :
   1,  Evaluation of the subject under consideration dynamic
 properties is of great importance when choosing the methods
 of investigation.
   Researches with the so-called "sharp" tests run in batch
 conditions are appropriate to be carried on during invest-
 igations of slow  inertial processes.  During the study of
 the processes with high inertia dealing with microorganisms
 acclimatization  the   continuous-flow  cultivation  method
 should  be used.
   2. The peculiarity of  the experiments with activated
 sludge is  the poor reproducibility of the results due to the
 time drift of activated sludge biochemical properties. This
 should  be taken into account  in carrying out the experi-
 ments and analysing the data obtained.
   3. For  investigations  of  the  kinetics of  low  inertial
 processes  connected  with the  effect  of  substrate, D.O.,
 activated  sludge concentrations and pH, temperature etc, it
 is appropriate to use manometric methods.
.  Special kinds of instruments -  respirometers - based on
 this principle permit to  run the experiments in  a wide
 variation  range  of parameters.
   4. It  is  proved experimentally that the effect of substrate
 concentration on the biological  treatment  rate may be
 described by the Michaelis - Menten Equation. The effect of
 MLVSS upon the rate of biological treatment is described
 by the lerusalimsky Equation taking account of the process
 inhibition  by products of metabolism.
   5.  The joint effect of substrate and D.O. concentrations is
 described quite satisfactorily by the  equation of a bisub-
 strate reaction proceeding in  accordance with the two-stage
 enzyme substitution.
   6.  The  generalized  kinetic   equation   was  obtained
 permitting the  effect  of the biochemical oxidation main
 components  to  be objectively taken into account.
   7.  Increase in  the  number  of carbon  atoms  in  the
 molecule of  substance causes decrease  in the biochemical
 oxidation  rate  and intensification of biological synthesis
 processes aliphatic alcohols  serve as the example of  this
 phenomenon.
   The  various  functional  groups  available   and their
 position in   the  molecule  of  substances produce   an
 important  effect on the process  kinetics.
   The oxidation rate  of izoalcohols is  lower than  that of
 alcohols with normal  structure. Biological degradability of
 isoalcohols decreases  from primary alcohol  to the tertiary
 one.
   When the number of carbon atoms in the molecule is the
 same and  the various functional groups determining  the
 chemical properties are available, the highest destruction
 rate is observed in normal alcohols and organic  acids.
   8. The   analysis of literary   and  experimental data
 obtained have shown that the relationship between the rate
 of oxidation  and molecular weight is very contradictory.
   The most satisfactory correlation for individual substan-
ces is being observed between the specific rate of oxidation
   and  the difference between COD  and BOD  as well as
between      and  COD-carbon  difference.  Relationships
obtained as a  result of statistical handling (27,29) allow us to
define the specific rates of oxidation for individual substan-
ces.
  The applicability of these relationships  to  the multi-
component substrates needs to be experimentally verified.
                                                         15

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Chemical Additions  to
Biological Treatment  of
Petroleum  Refinery
Wastewater
Allen Cywin*
U.S.E.P.A.
Introduction
  The form  contaminants  take  in  petroleum  refining
effluents is very important to the design and operation of
end-of-pipe treatment  facilities and  include  suspended,
colloidal and soluble materials. In the raw waste loads, most
BOD and COD  frequently occurs  as suspended  and
colloidal matter. Certainly, gross quantities of contamina-
tion tend  to exist as colloidal and  suspended  matter,
whereas variability of soluble components  is much more
limited. Therefore destabilization and chemical removal of
colloidal and suspended matter in a chemical pretreatment
step substantially lowers and equalizes contaminant levels
prior to secondary treatment. This of course leads to savings
in costs  and energy in biological treatment.
  Table I provides  an  overview  of various  treatment
processes that may be employed in producing an effluent of
drinking water quality from petroleum refinery wastes.
  'Senior Science Advisor, Office of Water & Hazardous Mate-
rials
  Presented at the Third U.S./USSR Symposium for waste water
treatment and control at Moscow, USSR, August 23-25, 1976.

  The  use  of chemical  systems  for  treating  specific
petrochemical  wastes, as  an addition to biological treat-
ment, has been successfully employed. The  most common
methods for  chemically  treating  petrochemical  wastes
include  neutralization,  precipitation,  coagulation,  and
oxidation, illustrated under the "Intermediate Treatment"
sequence of Table 1.  (1) (2)
  Pre- and primary treatment may  be required to remove
certain materials which would adversely affect the biological
system.  Oils  are difficult for the organisms to metabolize
due  to  their  low  solubility.  Inorganic  and  non-
biodegradable  organic suspended solids will tend to build
up in a treatment system, decreasing the  proportion of
active biological solids, and thus adversely affecting the
treatment efficiency. Sulfides react with dissolved oxygen
and reduce the oxygen  available to the organisms. Heavy
metals are toxic at defined concentrations and must be
removed or reduced to safe levels. Also, waste streams with
potentially toxic organic compounds should be separated
and treated prior to treating in a biological system.
Sequence
Primary
treatment
Treatment
1. Removal
of gross
amounts
of hydro-
carbons
and solids
Processes
Primary API
separators
Objectives
Removal of free
oil and solids
                                                          Intermedi- 2. pH control Mixing and
                                                          ate                   neutrali-
                                                          treatment              zation
                                   Adjust pH to
                                   proper range for sub-
                                   sequent treatment  by
                                   immediate oxygen de-
                                   mand  (IOD)   reduc-
                                   tion,   filtration  and
                                   ASP operation in nitri-
                                   fication mode
                                                                   3. Immediate Aeration and  To reduce im-
            oxygen
            demand
            (IOD)
            reduction
          4.  Removal
             of col-
             loidally
             dispersed
             phase
Secondary 5.
                                                         Tertiary
Dissolved
organics
and
ammonia
removal
          6. Phase
            removal
mixing       mediate oxygen
             demand and peak
             concentrations of con-
             taminants by air
             oxidation and
             equalization in a
             series of basins

Chemical      To reduce oil,
coagulation    biochemical
and filtration   oxygen demand
             (BOD) and chemical
             oxygen  demand
             (COD). Removal of oil
             makes  ASP more op-
             erable in desired mode.

Completely    To maximize
mixed        removal of am-
activated      monia and BOD,
sludge process  COD causing sub-
             stances.
          Filtration
Chemical Treatment
            To maximize
            effluent quality  by re-
            moving suspended sol-
            ids and their associa-
            ted BOD, COD and
            threshold odor causing
            substances.
  Neutralization and pH Adjustment - Neutralization of
petrochemical wastes may be desired for several reasons,
including:
  a) preparation of a waste for biological treatment,
  b) preparation of a waste for direct discharge,
  c) pretreatment for efficient coagulation,
  d) prevention of attack and corrosion of conveyance or
     process  equipment, and
  e) prevention of unwanted precipitation of waste compo-
     nents.

  Neutralization implies the adjustment of a wastewater pH
to values at or near neutral pH; i.e., pH seven. (However,
most  petroleum  refinery biological treatment systems
operate efficiently at pH  6-8.) Types of wastes generally
neutralized are (a) dilute acid or alkaline wash waters; (b)
spent caustics; (c) acid sludges from alkylation, sulfonation,
sulfation, and acid treating processes; and (d) spent acid
catalysts (3).
  Acid streams can be neutralized by mixing the waste with
lime slurries, or by adding caustic soda (NaOH) or soda ash
(Na2COj). Limestone beds (CaCOs) are occasionally used,
                                                     16

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either as an upflow system or a downflow system.
  Sulfuric acid (HiSO*) is the most common neutralizing
agent used  to neutralize spent caustic  wastes, although
hydrochloric (HC1) can also be used.  Acid sludges are
normally hydrolyred to free  acids prior to their  use as
neutralizing agents. Spent caustic neutralization with an
acid can be designed as a batch or a continuous system. The
carbon  dioxide in flue gases can also be used to neutralize
spent caustic solutions. Flue gas neutralization is economi-
cally feasible provided that the gases are available at high
enough pressures so that no compressor is required to inject
them into the spent caustic solution. It neutralizes alkaline
wastes by the forming of a weak carbonic acid. Spent acid
catalyst and sludges have been spread in pits filled with lime,
limestone, or oyster shells for neutralization. It should be
noted that pH adjustment is commonly used to facilitate
coagulation and precipitation.
  Coagulation - Precipitation • The addition of coagulants
under proper conditions causes the formation of a settleable
precipitate   containing  waste  materials  which can be
removed  by  conventional  sedimentation  or flotation
processes. It should be  noted  that coagulation is always
followed by some  type of solids-separation  process. The
most  commonly  used coagulants are hydrated aluminum
sulfate  (alum),   ferrous sulfate,  and  ferric  salts.  The
conventional coagulation system utilizes  a rapid mix tank
followed by slow  agitation  of the mixture  to promote
growth of  floe particles which settle.  The sludge-blanket
clarifier, which provides mixing, flocculation, and settling in
the same unit, has had many industrial applications because
of its compact dimensions.
  Coagulant  aids  are  sometimes  necessary  to promote
bridging between floe particles and render the floe more
settleable. The most common coagulant aids  are activated
silica,  bentonite  clays,  the  organic polyelectrolytes, and
water  treatment  clarifier  sludge.  The  three types  of
polyelectrolytes  are categorized by their electrochemical
nature, specifically, cationic, anionic, and nonionic.
  Organic  polyelectrolytes are helpful in improving the
effectiveness of the  air flotation process and in obtaining a
high  degree  of  clarification.  In  many  plants organic
emulsion breakers  have replaced  traditional alum  treat-
ments.
  Besides  yielding  a  better  quality effluent, organic
emulsion breaker programs,  by reducing the dosage of
inorganic chemicals, can also reduce the amount of sludge
generated by 50-75%. A significant saving in further sludge
treatment, or truckout, can be realized because the sludge
resulting  from   the organic  polyelectrolyte  treatment
contains at least as much oil as in the inorganic sludges, but
in a much  smaller volume. Plants that incinerate  sludge
have  realized a  higher  value (Btu per  pound) with the
organic sludge.
  Provisions must be made for the disposal of the sludges
formed by  the settled precipitates from  coagulation-pre-
cipitation processes. Landfills are the most common form of
inorganic sludge disposal, while organic sludges are usually
dewatered  by some  filtration  method and  subsequently
incinerated  or buried.
  High molecular weight cationic polyacrylamide floccu-
lants produce efficiencies in sludge dewatering  processes.
  Figure 1 illustrates in simple form the use of polyelectro-
lytes  at other  points  in  the  biological  process where
emulsion breakers may enhance the system.
  These are usually applied  after jar  and/or pilot  tests
determine which of the many polyelectrolytes available will
be  most efficient.  For high-rate  and  extended  aeration
systems (F/M ratios >.6 +< .2, respectively) cationic "pol-
yamine" coagulants often work  best.  For  conventional
aeration (F/M  ratios  0.2  -  0.6)  systems  polyacrylamide
cationic coagulants are  often preferred,  as  illustrated in
Figure 2.
  A full comparison of an acid-alum-lime treatment system
and an  organic polyelectrolyte emulsion breakers program
shows these advantages for the organic system:
  (a)  lower total dissolved solids in the effluent for plant re-
      use;
  (b)  elimination of final clarification and lime or caustic
      neutralization; and
  (c)  reduction  in corrosion rates, alum usage, and sludge
      generation.
  Oxidation processes - Oxidation processes are used  to
treat  both  organic and  inorganic  contaminants using
oxygen  or other chemicals as the oxidizing agents.  The
oxidation of sulfides to sulfates using steam  and air is an
effective treatment method;  however,  wastes containing
high  concentrations of phenol cannot  be treated in this
manner because phenols interfere with sulfide oxidation. If
large  quantities of mercaptans or mercaptides are present in
the waste, a reoxidizer may be required to insure  complete
oxidation.
  Catalytic oxidation is usually applied when the fuel value
of a  waste is too low for  conventional incineration. The
process  was  originally  designed  to  operate  in the vapor
phase but has been successfully applied  to aqueous wastes.
Laboratory studies have shown that dilute aqueous organic
wastes could be effectively  oxidized at temperatures below
600° C by using a copper-chromate catalyst. Investigations
have  demonstrated that  hydrocarbons   also  could  be
oxidized by using metal oxide catalysts. The  initial cost of
catalytic oxidation units may be 20 to 30 percent greater
than  that  for conventional  incinerators, but for dilute
organic wastes the operating  costs may  be 15 to 20 percent
less.
   n
(owl I-
IlltM
I*Ht

T
AM
laprtur


          I1*M twi
       . »1« Mrfyl"	
      (HMO**-** Bll to Dm) to*)
                                                            Figure 1
                                                        17

-------
                                                    -
 |>H HtJJultWM U i-l
Figure 2
  Chlorine  (Ci)  has been  used  successfully  to oxidize
phenol and cyanide in petrochemical wastes. The oxidation
of phenols must  be carried to completion to prevent the
release of chlorophenols which cause  objectionable tastes
and odors in drinking water. Cyanides can be oxidized to
carbon dioxide and nitrogen by  chlorination if the pH is
maintained in excess of 8.5 and sufficient chloride used, thus
preventing the release of toxic cyanogen chloride. Chloride
dioxide has  been  shown  to  overcome these and other
disadvantages of chlorine  and  hypochlorite oxidation,
although this treatment is very expensive.
  Ozone (Os) has been proposed  as an oxidizing agent for
phenols, cyanides and other unsaturated organics because it
is a  considerably stronger oxidizing agent than chlorine.
The  chief disadvantage in the United States is the high
initial cost of ozone generation equipment, although there
seems to be  more  experience in  the USSR (for drinking
water) where the costs may be different. Ozone has several
advantages,  one of  which is its ability to react rapidly with
phenols and cyanide.
  Miscellaneous Methods - Ion exchange has been used to
remove   specific  petrochemical   pollutants.  Quaternary
ammonium anion resins have successfully removed phenols
in the laboratory.
  A  full  scale  demonstration  of  a  chemical-biological
treatment of petroleum refinery waste water  has  been
completed. The results of recent E.P.A. sponsored research
investigations (4) of the AMOCO  company's Yorktown
refinery waste lagoon effluent and  API  separator effluent to
determine the applicability  of coagulation/mixed-media
filtration  on these  streams  illustrates  the efficiency  of
combining these techniques. This relates to step 4 of Table I
(removal of colloidal material).
  Coagulation/mixed-media  filtration  - Mechanisms for
retention of  solids within  pores  of filter  media may  be
separated into two principal processes:  a transport step and
an attachment step. The transport step involves movement
of the dispersed  phase material to the vicinity of the filter
media surface, and the attachment step involves attachment
of the  particles  on the  media  surface.  The   transport
mechanisms may  involve diffusion, interception, sedimenta-
tion  and hydrodynamic actions.  The  attachment mecha-
nisms may involve  van der Waal forces, electrical double
layer interaction, mutual adsorption or hydrogen bonding
or ionic forces. Experimental comparisons  of the filtration
of colloidal, ferric hydroxide suspensions with the filtration
of well  flocculated  suspensions of ferric hydroxide, both
performed under identical conditions of filtration, demon-
strate a much higher filtration efficiency for the floe. Studies
 have shown  that  removal  of colloidal  suspensions  by
 filtration appears to be possible  only  when the colloidal
 particles  to be  filtered  carry  an  electro-kinetic  charge
 opposite to the charge of the filter media used. The removal
 of the colloid is by electro-kinetic sorption of the colloidal
 particles  on the  surface of the filter media. This kind of
 "filtration" phenomena seems to have limited application to
 the filtration of industrial waste water because of complica-
 tions encountered in application,  the complexity of which
 are beyond the scope of this paper.
   Colloidal Destabilization - In most cases, the application
 of filtration to petroleum refining waste waters will not be
 optimized unless the colloidal  material in suspension is
 destabilized by essentially neutralizing the surface charge on
 the  colloids.  The  neutralization  of  the charge  using
 conventional  primary coagulants  is  simple,  but  must
 recognize the condition of the water. Overdosing with alum,
 for example, can be a most deleterious  response to a direct
 filtration system  that is not performing satisfactorily.
   Stumm  and  O'Melia  (5)  describe  the  equilibrium
 composition  of  solutions  in  contact  with  precipitated
 primary coagulants  in the  interesting manner shown in
 Figures  3  and 4. These diagrams  are calculated using
 equilibrium constants for solubility and hydrolysis equili-
 bria. The  shaded  areas  A  and B  in each  figure are
 approximate  operation  regions   for  air  flotation  and
 clarifiers  (region  A) and  direct filtration (region B). Both
 regions are assumed to cover a pH range of 6.0 to 8.5. The
 coagulant dosage ranges from 33  to 200 mg/1 in region A
 and 3.3 to 20 mg/1  in region B. These  figures are useful in
 the interpretation of some filtration results.
   With reference to Figure 4, the isoelectric point for ferric
 hydroxide coincides with the region of minimum solubility,
 and operating regions for water  treating (destabilization)
 always  yield  a  hydrolyzed  primary  coagulant with a
 desirable,  positive, zeta potential.
l-a!-
A - Ojwntlng Region for Air
   noutlon md ciiririm
B - Operating Region for
   Direct mtr.tlon

    13(oa)^

« - «,<<<
r - Ai3'
  Flgur* 3  Bqulltbriua competitions of solution! In
           contact with Al(OB)3
                                                        18

-------
               A - Operating Region for Air Flotation end Clarlflera
               B - Operating Region for Direct Filtration
               C - Fc(OH)£
                     \ ^^—— Fe(OB)j (a)
Figure 4. Equilibrium compositions of solutions in contact with
Fe(OH).i

   In many refinery situations, however, it is difficult to use
this desirable condition because the presence of sulfides and
strongly reducing conditions cause the reduction of ferric to
ferrous iron and the formation of mixed iron  sulfides with
no coagulation powers. In fact, in some refinery waters the
use of iron coagulants at modest dosages may contribute to
stabilizing solids rather than destabilizing them.
   While alum has no redox or sulfide chemistry comparable
to  iron,  its  amphoterism  and   solubility pose  definite
limitations on alum usage. With  reference to Figure 3, a
substantial portion of operating region  B  lies in the area
where alum  is soluble and the predominant equilibrium
species is negative, A1(OH)4. In  the more acidic part of
region B,  however, the concentration of equilibrium ionic
species is very  much  lower  and much  less negative.
Considering these data, it is not unexpected that investiga-
tors  consistently  report optimal coagulation/flocculation
results with alum at a pH of 5-6.
   With inspection of Figure 3, one may question why alum
is effective at all for neutralizing negatively charged colloids
in  the indicated  operating regions.  One approach  to
explaining observed performance requires understanding
that  the data in Figure 3 are equilibrium data; but before
equilibrium is  reached,  substantially different conditions
exist.
   Alum very readily hydrolyzes  to form  polymers in  a
complex manner not well defined.  The hydrolytic pathway
and reaction rates are affected by pH, temperature, other
ions, etc.  The hydrolytic reactions are  not instantaneous,
and as they proceed, positively charged hydroxo polymers
are formed which are available for colloid adsorption. The
hydrolyzed species  have enhanced adsorption capabilities
possibly due to larger size, less hydration, and  the presence
of coordinated  hydroxide  groups. In  solutions  more
alkaline than  the isoelectric point, the  positively  charged
polymers   are  transient  and,  at  equilibrium,   anionic
polymers  prevail.   In   modestly   alkaline  solutions,  the
transient,  positively charged polymers appear to contribute
to  destabilization   of  colloids.  On the other hand,  in
solutions  more acidic  than  the isoelectric  point,  the
positively  charged  polymers prevail at equilibrium and
 destabilization of colloids is achieved at significantly lower
 coagulation treatment levels.
   While coagulation/flocculation  of refinery  waste water
 can frequently  be achieved over a  wide  pH  range using
 primary  coagulants  supplemented  with  polyelectrolytes,
 typically there  is  a  very  definite optimal  pH that may
 simplify, or even be required by, direct filtration. Operating
 at the optimal pH yields benefits of  maximum removal of
 discontinuous phase  material with minimal  coagulant
 requirement and sludge generation.
   Frequently, refinery  waste waters  only require 5 to  10
 mg/1 of primary coagulant at a pH  range of 6 to achieve
 destabilization for filtration. When  this level  of chemical
 treatment is observed in jar tests, the  coagulant dosage may
 be much below  that  required  for generation of  floe;
 however,  excellent filtration  results are  achieved.  The
 destabilized particles penetrate into  the pores of the  filter
 media, the media aids  the flocculation process, and the
 particles  are effectively trapped with high solids loadings.
 Too much primary coagulant can be added at a pH of 6 and
 some suspended matter restabilized.  Too  much coagulant
 puts an unnecessarily heavy solids burden  on the filter and
 the  result  is rapidly  increasing pressure  drops, early
 breakthrough and excess backwash sludge to  handle.
   At a pH  of 8, substantially more primary coagulant may
 be needed to neutralize the zeta potential.  The dosage may
 be 30 mg/1 or more with the  generation of a substantial
 floe size  instead of the almost invisible pin-point  floe of
 suspensions successfully  filtered at a pH  of 6. The more
 voluminous floe does not penetrate into the  filter media as
 well as does the  pin-point floe and  lower solids loading,
 higher pressure drops, and more chemical usage, backwash
 and  sludge volumes result.
   At a pH  of 9, the zeta  potential of the system may never
 be neutralized and, of course,  is  not optimal as such for
 direct filtration. With iron salts, chemical coagulation/floc-
 culation at  a pH of 9 or more can yield superb results with
 some  waters, but a different  clarification  mechanism is
 involved. Comparatively large dosages of  coagulant  are
 used  which generate  large, voluminous  floe particles that
 trap and enmesh the suspended matter in the  water being
 treated and retain the  solids in the  sludge blanket.  This
 approach is not optimal for direct filtration but requires
 pretreatment in a  clarifier to handle the voluminous sludge
 volume generated. The clarifier water is then  polished by
 filtration  using polyelectrolytes to destabilize the residual
 suspended matter.
  Figure 5 illustrates the effect of treating a refinery effluent
water with  fixed levels of overdosage, underdosage,  and
optimal dosage of primary coagulant  at various pH  levels.
For  this example, the  optimal dosage  is defined as the
coagulant required to bring the zeta potential of the system
into the target zeta potential range of ±5 mV necessary for
destabilization of the suspended  matter  preparatory to
direct filtration. To emphasize the importance  of pH for
these  systems of over,  under,  and optimal  treating with
coagulant,  there  is a  pH  range where  the  system  is
destabilized and receptive to clarification by direct  filtra-
tion.
  For  the  optimal dosage in curve  A, the  system  is
destabilized  over  the widest  pH  range  of 5.5 to  8.4.
Underdosing (curve C)  provides a destabilized system for
filtration only at a pH of  about  6.5 or less. Overdosing
                                                        19

-------
(curve B) results in the narrowest pH range for effective
destabilization of about 0.6 pH units, i.e., 7.65 to 8.25.
  Refinery effluent waters may vary rapidly in pH over a
short time span  which makes it desirable to determine the
optimal coagulant-pH balance. Frequently, poor or no pH
control is available. In these cases,  the destabilization of
suspended matter  frequently can  be "desensitized" to pH
somewhat  by using coagulant/ polyelectrolyte  combina-
tions. The preferred operating procedure that frequently
makes the filtration system essentially free from upset is a
two chemical system: a primary coagulant supplemented by
a polyelectrolyte. Two cases seem appropriate: 1) For the
operating range of 6-9 pH, an  underdosage of primary
coagulant is  used  and is  supplemented by  addition  of a
cationic  polyelectrolyte.  This combination of  chemicals
broadens the effective pH range of destabilization of curve
C in  Figure  5, and, additionally, the chemical properties
more adherent to the filter media.  2) For  the  operating
range of 5-7 pH, the polyelectrolyte used to supplement the
primary  coagulant may be a  non-ionic or very weakly
anionic. The non-ionic or very weakly anionic polyelectro-
lyte is useful in systems that  tend  to modest overdosage
situations with primary coagulant. Massive overdosing with
primary  coagulant can be compensated for somewhat by
non-ionic or very weakly anionic polyelectrolytes  but
rapidly blind the filter. These chemical treatments are also
useful when high hydraulic loadings are applied to the filter
or rapid rate increases occur, both of which may tend to
redisperse  trapped  solids  and  cause premature  break-
through.
  Strong, or very strong, anionic polymers usually perform
the poorest  in tests comparing  cationic, non-ionic,  very
weakly anionic,  weakly  anionic,  fairly strong anionic,
strongly anionic, and very strongly anionic polyelectrolytes.
In one instance,  treatment with only a cationic polyelectro-
lyte  at  a  less  than  1  ppm   outperformed  all  other
combinations of chemical treatment for destabilization of
suspended matter preparatory to  filtration.
  Another distinction that may be important is the nature
of the colloids to be destabilized: inert materials including
clays,  silica,  coke fines, oil particles, etc., or biocolloids
consisting chiefly of bacteria. Amoco's (4) work on colloid
destabilization at other refineries has been largely on inerts,
or a  mixture of colloids predominately  inerts with some
biocolloids. The work of McLellon et al. (6) and Stumm et
al (5) indicates  that  where  principally  biocolloids are
concerned, stability is less dependent on  repulsive electro-
static interactions  and relates  primarily to the interaction
of the hydrophilic surface of the  biocolloid with the aque-
ous solvent. The source of colloid surface charge is through
acid-base interactions of ionogenic functional groups. The
authors cited conclude that aggregation of biocolloids is by
chemical interaction of the hydroxy metallic polymers with
the ionogenic groups of the colloid followed by chemical
bridging. If the destabilization mechanism for biocolloids is
such  a special case, the  chemical  pretreatment  may be
optimized by emphasizing  the  use of  organic polymers
known to form chemical bridges.  The optimal chemical
pretreatment would then be expected to be a multichemical
system.  -
  Tests  indicate that in warm  brackish water  a  two-
chemical system at low concentrations was satisfactory
whereas  for cold brackish water a three chemical system at
higher concentrations may be required.
  •30
  -JO
A - Optlul Iron Salt Dostgi
B - Ovtrdote wltb Iron
C - Under Doiige with Iron
D - Ttrgtt z«u PolentUl Ri
                             pH
Figure 5. Variation of final zeta potential with pH when treating
refinery effluent having negative zeta potential with three levels of
coagulant dosage

  Polyelectrolytes screened vary widely in effectiveness, and
optimizing chemical pretreatment involves testing a series of
commercial  polyelectrolytes at various combinations until
an optimal combination was found (7)
1. Two Chemical Systems
   a) Optimize pH.
   b) Use a  primary coagulant plus an organic cationic
     polyelectrolyte, or
   c) Use a primary coagulant plus an organic non-ionic or
     weakly anionic polyelectrolyte.
2. Three Chemical Systems
   a) Optimize pH.
   b) Use a primary  coagulant/ organic cationic polyelec-
     trolyte/weakly anionic polyelectrolyte treatment se-
     quence.
  Nutrients  - Effective biological treatment of any organic
contaminant requires the availability of essential nutrients
for the organism. The mineral nutrients required by bacteria
are available in sufficient amounts in most wastewaters, but
nitrogen and phosphorus requirements are more critical and
many petrochemical wastes are deficient in one or both of
these elements. Nitrogen (N) and phosphorus (P) require-
ments  for biological treatment have been related to the
magnitude of the degradable organic content of wastewater
as represented  by BOD.  Generally, a BOD:N:P ratio  of
100:5:1 will provide sufficient amounts of these nutrients.
Nitrogen  is  most readily  available in its reduced form  as
ammonia, ammonium  ion, or  amino nitrogen. Organic
nitrogen, nitrates, nitrites, and organic compounds contain-
ing  these forms can also be  used,  but  a considerable
expenditure of energy is required to reduce these forms to
ammonia nitrogen. Phosphorus is usually added in the form
of phosphoric acid or soluble phosphorus  salts since they
are most  readily assimilable.

Summary

  In summary, biological treatment is the key end-of-pipe
element in the  overall  treatment systems, for petroleum
                                                       20

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refinery wastes.  Therefore the unit processes within the
treatment  system  should be optimized  to  utilize  the
biological process for removal of soluble contaminants. In
the United States we have learned that the use of chemical
pretreatment as  well as other physical processes (such as
dissolved  air flotation and  mixed media  filtration)  will
enhance  the performance of the  biological  systems  by
removing colloidal and suspended  matter. This not only
improved the efficiency of the biological treatment process
but saves on cost of equipment and operations.

References

1. Grutch, J.F. and Mallatt,  R.C., Optimize the Effluent
     System, Hydrocarbon Processing (March 1976)
2. Lacy,   W.J.  and  Cywin,  Allen,  Physical-Chemical
     Treatment  of  Wastewaters from  the  Petroleum
     Refining - Petrochemical Industry Joint U.S. - USSR
     Symposium; Cincinnati,  Ohio  (November 1975)
3. Halper, Martin and Cywin, Allen, Development Docu-
     ment for Effluent Limitations Guidelines and New
     Source  Performance Standards for the Petroleum
     Refining Point  Source  Category, Environmental
     Protection  Agency, EPA - 440/1-74-014-1,  (April
     1974)
4. Grutch, J.F., Mallatt, R.C., and Peters, A.W., Chemical
     Coagulation/Mixed-Media  Filtration  of  Aerated
     Lagoon Effluent, EPA - 660/2-75-025, (June 1975)
5. Stumm,  W.  and  O'Melia, C.R., Stoichiometry  of
     Coagulations, Jour. AWWA 60:514 (1968)
6. McLellon,  W.M.,   Kernath,  T.M.  and   Chao,  C.,
     Coagulation of Colloidal and Solution Phase Impuri-
     ties   in  Trickling  Filter Effluent,  Jour.  WPCF,
     60(1):77-91, (1972)
7. Surchek, J.G., and Tutein, T.R., Simplified Method
     Determines Cost  Performance of Polymeric Floccu-
     lants. Water and  Sewage Works (January 1976)
                                                      21

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MINISTRY OF HIGHER AND
VOCA TIONA L SECOND A R Y
EDUCATION OF THE USSR
LENINGRAD INSTITUTE OF CIVIL
ENGINEERING

S.M. Shifrin, B.C. Mishookov, G.V. Ivanov,
E.K.Goloobovskaya


The Trends  in Intensification

in  Biochemical Treatment  of

High  Density  Wastewater

  Intensification of biochemical treatment of waste water
which has high density of organic matter may be carried out
in a  number of ways, the major ones being the following:
  —increase  in  load imposed  on microbial mass  by
establishing the optimum  conditions for activated sludge
behavior;
  —usage of high density  activated sludge;
  —usage of thermophilic activated  sludge.
  The first trend is implemented by increasing the density of
microorganisms and reducing the retention period of liquid
inside the aeration tanks. When the density of microorga-
nisms increases, the  rate  of their removal goes  up; the
relation between the treatment rate and the increase in
density of microorganisms is of non-uniform nature. Fig 1
shows  an  example  of  dependence  (which  has  been
established  by us)  of treatment  rate  on the density of
microorganisms in  sludge-liquid mixture in the aeration
tanks with the oxidation  (under contact  conditions of
organic matter in the influent coming from  the  food
industry enterprises.
  The dependence of treatment rate on the organic matter
density is of S-shaped form and somewhat differs from well-
known patterns established by Michaelis-Menton;  Monod
and others.
  In general the rate of treatment may be represented as an
equation of trimolecular reaction
           r=      =-K  (C)n(D)m(0)P
(D
where C,D,O - respectively, densities and concentration of
  organic matter, activated sludge and dissolved oxygen in
  the liquid;
K - the constant value of the reaction rate;
n,m,p - empirical values.

  It is generally accepted that dissolved oxygen concentra-
tion in excess of 0.5-1.0 mg/1 is of little practical significance
for the  biochemical treatment  rate, provided the mass-
transfer of oxygen is not connected (as is the case in diffused
aeration systems, for example with the speed of agitation of
sludge-liquid mixture.) If the oxygen concentration and the
speed of agitation related to it do not restrict the treatment
rate,  then  the  formula (1)  turns into an  equation of
bimolecular reaction. Within the wide range of concentra-
        tion changes the values of "n" and "m" are the variables.
        The value of "n" ranges from 2 to 0.5 with little and medium
        loads on activated sludge and is reduced to zero when the
        load increases. The value of "m" is frequently assumed to be
        the constant (in case of narrow ranges of changes of "D"
        value),  although   in  general "m"  decreases  when "D"
        increases. One  can compare the  efficiencies of treatment
        only on the basis of rate "r" as with the changes of "n" and
        "m", the value of "K" becomes incomparable. In view of this
        it is advisable to apply the first criterion of Damkohler
        Daj
                   Daj
                               - r. 1
                                 v • c
(2)
        Where r - Treatment rate;
              1 - determining linear characteristic;
              v - determining velocity of liquid movement;
              c - concentration of matter going into reaction.

          When applying this criterion to wastewater biochemical
        treatment it is possible to change the  criterion somehow
        taking into account the equation (1):
              Da,
                    kcnpmbp_
                       vC
  Damkohler's modified criterion under the equation (3)
enables to compare efficiencies of treatment of a specific
kind of wastewater while  changing the organic  matter
density (C), the activated sludge dosage (D) and  the
aeration duration.
  The way the treatment rate changes (Fig. 1) indicates that
usage of one-stage facilities  is  not advisable since  the
treatment average rate in such facilities turns out to be low.
  Treatment in two-stage or three-stage aeration facilities in
which the optimum conditions for existence  of specific
activated   sludge  are  provided   is economically  more
preferable. On the basis of  our research one may come to
the conclusion that the two-stage treatment is applicable
with the organic matter density  of up to 8.0  - 12.0  g/1
(calculated at the bichromate COD), while the  three-stage
treatment is advisable when the density calculated at the
COD is within 10.0 - 15.0 g/1. It  should be borne in mind
that we are dealing here with the organic matter which
undergoes oxidation without great difficulties  during the
biochemical treatment (wastewater from the food industry
enterprises, influent  from live-stock farms  etc.)  The
establishment  of optimum conditions for activated sludge
existence in each stage of aeration facilities provides for the
proper speed of agitation and supply of dissolved oxygen.
In the first stage of aeration facilities the proper agitation
and dissolved oxygen supply is achieved  with the electric
power consumption of up  to 100 watt/hour per  1m3 of
volume, in the second stage - up to 70 watt/h/m3, in the
third stage - up to 50 watt/hM3 (these power consumptions
hold good for the aeration facilites with the capacity of 150-
500 m3). Dissolved oxygen is contained in the  liquid at a
level of 0.1-0.5 mg/1 in the first stage; 2.0-3.0 mg/1 in the
second stage; 3.0-4.0 mg/1  in the third stage. Nitrification
was observed in the second and third stages. The third stage
usually acts as an aeration-nitrification tank and at the same
time it acts as a preventive means to hold up the microbial
                                                    22

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mass which is periodically entrained by the effluent from the
second stage.
  The organic matter oxidation rate amounts to 200-300
g/hour of COD per 1  m3  of volume  of the  first stage
aeration tank, 100-150 g/m'/h in  the second stage, 10-30
g/m3/hour in the third stage, while the treatment efficiency
makes up  approximately 50,80 - 90,95 - 97% of COD
respectively  after  the  first, second  and  third  stages of
aeration tanks.
  The second trend  in stepping up the treatment provides
for an increase in density of microbial mass in the facilities
(higher density  of activated sludge). The increase in the
microbial mass volume results in the reduction of specific
velocity  of  organic  matter removal  per  unit  weight of
microorganisms. At  first sight higher density of activated
sludge does not yield an anticipated result. However,  it
should be borne in  mind that activated sludge  of higher
density has considerable Constance and is able to withstand
drastic changes in density with comparative ease, which is
typical of the high density wastewater.  Higher density of
activated  sludge  is achieved  through employment of
intensive means of microbial mass separation - by filtration,
flotation and prolonged settling. But not all these means are
applicable to hold up  the microorganisms  after the  first
stage  of aeration facilities. High rate treatment in the  first
stage  generates the microbial mass consisting of very  fine,
badly flocculating  particles,  so that the holding up of this
mass  is a rather complicated problem. The sedimentation
properties of microbial mass are influenced positively by the
inert  solids  in the form of specially introduced medium,
such  as  activated  carbon, or in the form of  suspended
matters contained in wastewater.  In view of the current
practice  of microbial mass separation the prolonged one-
stage  or two-stage settling proves to be the least expensive
and the most feasible one.
  In the multi-stage aero-accelators  designed for treating
live-stock farm wastewater the activated sludge density was
maintained equal to  10-18 g/1 in the first and second stages
and 6.0-8!o g/1 in the  third stage.  The influence of the
activated sludge density on rate and efficiency of treatment
comes to be observed when the density is reduced to 6,0-8.0
g/1.  After the  microbial mass has passed through the
second stage of aeration tanks the sedimentation properties
of the mass becomes better and the  density of suspended
matter in treated wastewater reduces to 100 mg/1 as a result
of settling.
  It is of certain interest to establish the weight of live cells
of microorganisms in the sludge by the DNA content. The
research into this problem has shown that the live cell
weight in the first stage makes up 30% calculated on the
basis  of the total weight of microbial mass, and 18% in the
second stage.'
  The third trend in  stepping up the treatment is prompted
by the high-rated biochemical treatment. When increasing
the density of organic matter up to  8.0-15.0 g/1 and the
treatment rate up to 100-300 g/m3/hour there takes place
the biothermal  warming-up of the  liquid caused  by the
excessive energy  emitted when  the  organic  matter  is
oxidized. For instance,  in  the  operating  aeration tanks
(located  inside  the building) the  liquid temperature  was
maintained spontaneously at 30-34° C while the influent and
the inside air had a temperature of 13-17°C. In view of this
fact it is advisable to carry out treatment in the first stages
under thermophilic conditions, i.e. at 50-55° C. The increase
in temperature will enable to increase the treatment rate by
1.5-1.8 times if there is high-rate  agitation  and sufficient
supply of dissolved  oxygen. Thermophilic aerobic  process
enables to destroy practically  all the pathogenic organisms
in wastewater, which is a  great advantage of this process.
The increased demand for air which is necessary to establish
aerobic conditions  is the drawback of the process as it
increases the cost of treatment.
  The  combination  of the above mentioned trends enables
to step up the treatment of high density waste-water and to
reduce capital investments and maintenance costs.
  Positive results in the field of biological water treatment
intensification have been recently  obtained by  special
preparation of waste water before delivering it  into the
aeration  tank,  the  preparation is accomplished  by the
preliminary treatment  of  waste waters according to the
method of  electric  flotation  coagulation  (EFC).  As the
result  the  contamination  concentration  is  considerably
reduced. F.e., the concentration of suspended matters of the
butchery by electric  flotation coagulation method decreased
the density  of suspended  matters to 95-98 per cent (from
2000 to 10-60 g/m3), COD by 60-70 per cent (from  1700-
2000 to 400-800  g/m'), BOD has been changed as well.
After EFC BOD  was 0.69, COD - 14.7 g/m3.
  Studies  of the biological  treatment of  waste waters
subjected to the electric flotation coagulation treatment in
the aeration tanks allowed to find out a number of specific
features.  It  was established that activated sludge differed
somewhat from the sludge treating the same effluent after
the usualy mechanical  treatments  its ash content was 15-
20%, sludge index was 180-200, dehydrogenation activity of
the regeneration  activated sludge  -5 -8 mg/g of the dry
weight. Usually sludge  floes were finer and more dispersed.
The composition of sludge hydrobyonts was more variable.
The increase of the number of rotaria and setacious worms
was  observed. The process of effluent purification after
RFG was rather intensive but the increase of sludge under
effluent conditions  was   only  12.7  mg/1 (2-3% of the
incoming  BOD),  and in the contact experiments was not
recorded at all. One could observe considerable increase of
sludge dehydrogenation activity (up to 30-50 mg/1), sludge
oxygen activity consumption, the increase of the microorga-
nism number and the number of bacteria. The absence of
notable growth of sludge may be explained by the fact that
under  the byological treatment of the effluent  containing
suspended matters the increase of sludge is connected with
the  sludge floes  sorption  of  the  suspended   matters
constituting  the  inert part  of  the  activated  sludge.
Suspended  matters  concentration in the case considered
amounted to no more than 50 mg/1, i.e., was several times
lower than after usual  sedimentation.
  High activity  of sludge  allowed  to accomplish the
purification process at   reduced  sludge  densities. The
concentrations  from  0.3   to  3.9  g/1 were tested. The
increased  doze from 0.3  to  0.8-1.0 g/1  proved  to  be
favourable for the process of contamination removal.
  Changing the sludge  concentration within  1.0 to 3.0 and
sludge loading from 1400 to 400 mg COD/g of dry sludge
respectively did not affect the duration of the process which
lasted 8 hours. In all the cases the complete purification was
ensured during this  period of time (See Fig. 2).
                                                       23

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  The tests carried out had also to determine the setting up
of  sludge  oxygen  consumption  and  dehydrogenation
activity.  The  analyses  have shown that the  process  of
impurities distraction from the liquid (sorption) and their
oxydation  take  place with  varying  velocities.  If the
impurities removal from the effluent approximated 3 hours,
the oxidation  of the  removed impurities required 6-10
hours. Impurities oxidation took place not only  with less
velocity  but depended to a large degree on  the  sludge
concentration. The higher the sludge doze was, the higher
was the % of the oxidized impurities compared with those of
sorbed.
  The results received  somewhat opposed the wide spread
opinion that the necessary aeration time is the  reverse ratio
of sludge concentration but they are quite consistent with
the laws established for natural ecological  systems. Any
aeration tank can be considered to be a kind of an ecological
system as it has the same features: the  limited  capacity
(biological  current); the  certain  amount  of  nutrition
(activated sludge); the process of energy transformation.  In
any ecological  system  the stability of existence  nutrition
conditions may be  maintained by means of  population
dynamics. With the increase of the population  density the
growth rate is reduced. Unlike the natural ecological systems
the population density in  the aeration tank is artificially
increased by the  recirculation  of activated sludge.  The
increased doze of sludge is necessary as it sets up the process
and ensures the stability of water works operation but under
these  circumstances the  rate  growth  of populations  is
decreased and thus their psysiological activity. By reducing
ferment activity aeration tank activated sludge compensates
to some extent artificially increased population density, i.e.,
in this way, the self-regulation of the aeration tank ecological
system is achieved. Within the required sludge density  its
activity is determined depending upon the conditions of the
ecological system as a whole.
  One of the main abiotic factors influencing the formation
of the ecological systems  is the provision of feed. Under
natural conditions the number of populations is the function
of food amount.  Any aeration tank does  not differ in this
respect from a natural  ecological system. The  increase  of
contamination concentration in the liquid  treated  results in
the increased  number  of populations  and  the increased
nutrition.
  Hence the increased sludge dose  is natural and efficient
only in the case of highly concentrated effluent.
  Increasing the sludge dose above the natural possibilities
of the system  causes'the relative increase  of the inert
(ballast) part of sludge and does not set up the purification
process.
  The lower the  sludge doze is,  the more effective works
every particle of the biomass, and so  the same  effect  of
purification  can be achieved under different sludge density
in the aeration tank.
  The limits  of  sludge  dozes  when  its self-regulating
qualities appear under other equal conditions are deter-
mined by feeding i.e., contamination concentration in the
water  treated.  Therefore  the  process of  waste  waters
treatment is determined not only by the sludge loading but
by impurities density in the aeration tank.
  As  sludge ensure the necessary efficiency of treatment it is
more  advantageous to carry out the process at the minimum
sludge doze as in this case the conditions of oxygen sludge
 supple are improved, and thus energy consumption per unit
 of the contamination removed is reduced.
   The EFC application as a means of preliminary effluent
 treatment of the butchery allows considerably to reduce the
 time of aeration with the subsequent treatment of this kind
 of effluent. Simultaniously the amoung of excess activated
 sludge is decreased.
                           HI stage   Estage ' I stage

Figure 1. Oxidation impurities curves related in time.
      123    6    8   10  12  14  16  18  20  22 i.Ai*

Figure 2. Kinetics of impurities distraction at various sludge doses.
   Sludge dose, g/l      Loading at the moment of stirring
                          mg COD/g of dry sludge
 1   0.40
 2   0.77
 3   1.99
 4   1.30
 5   2.06
1420
 643
 643
 400
 712
                                                       24

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 Steel  Industry  Wastewater

 Treatment  Using Biological-

 Chemical  Technology*

 William J. Lacy, P.E.**

 Introduction
   The steel industry  in the US is  composed about  102
 companies operating 420 plants. Of these, 63 are integrated
 plants, 96 are  nonintegrated,  and 261  are hot  and cold
 working  plants. These plants are located  in almost every
 state, but the principal concentration is in the northeast
 quadrant of the  country in  the States  of New  York,
 Pennsylvania, Ohio, Indiana, and Illinois, see Fig. 1.
   Generalizations about steelmaking operations  are diffi-
 cult because exceptions can  be found in every mill. Steel
 mills in operation today range from older marginal mills
 built early in this century to  new modern facilities built in
 the last several  years.
   Significant waterborn wastewaters result from all steel
 mill manufacturing operations.  These wastes are principally
 suspended solids, oils, waste  acids,  ammonia, cyanides,
 phenols,  chlorides, fluorides, sulfides, heavy metals, and
 heated discharges.
   Basic processing operations shown in Figure 2, include:
 by-product coke manufacturing; sintering operations; blast
 furnaces;  steel  making  (electric furnaces, basic oxygen
 furnaces,  and open hearth furnaces); vacuum  degassing
 operations; continuous casting;  rolling mill operations; and
 finishing  operations.

 •Presented at the  Joint US-USSR  Water Pollution Control
 Symposium in Moscow,  USSR,  August 22-28,  1976.
 ** Principal Engineering Science  Adviser, Office of Research and
 Development, U.S.  Environmental Protection Agency, Washing-
 ton. D.C.

Source  of Pollution

  Each of these basic operations contains a large complexi-
 ty of pollutant discharge into  the environment. For  the
coking operation, wastes are   emitted from  the  waste
ammonia  liquor, still wastes, final cooler wastes, and light
 oil  recovery wastes.  The   blast furnace,  with similar
pollutants to the  coking operation, has its main aqueous
waste resulting  from gas  cleaning with  wet washers. The
actual steel making operation also generates liquid wastes
from the air pollution control equipment, such as: sparking
boxes, spray   chambers,  and  venturi  scrubbers.  The
degassing operation has liquid wastes from the barometric
condenser cooling water.  Cooling water discharge results
from the casting operations,  whereas, dust control equip-
ment creates the sintering  operations wastewater.  The
rolling mill operation has  wastewater from the  scale,
lubricating oils, spend pickling operations, and pickling
rinse waters.
  Treatment technology differs for each of the respective
unit operations. The  coking operation employs, for the
waste ammonia liquor, anhydrous recovery, bio-oxidation
of cyanides and phenols, and ammonia denitrification, and
possibly total incineration. Closed loop is achievable for the
 final cooler water with a minimum blowdown. Recycle is
 available for the light oil recovery wastes. The  vacuum
 degassing  operation treats  its  cooler  water  wastes by
 sedimentation, filtration cooling and recycle. The continu-
 ous casting mode recycles spray cooling waters with scale
 pit sedimentation followed by filtration or cooling. The
 sintering phase employs dry dust collection and gas cleaning
 equipment  for  new  plants  whereas the  wet  systems
 incorporate a complete recycle  consisting of a thickener
 (polyelectrolyte addition), vacuum filter and clarifier. The
 recycle blowdown consists of, aeration for oil removal, lime
 precipitation, fluoride neutralization, and final thickeners.
   The rolling mill operation (Fig. 3) employe crude settling
 chambers for  scale and oil recovery, lime neutralization and
 evaporation-condensation  for  strong  pickling  wastes,
 recovery of oily wastewaters by primary belt skimming,
 chemical coagulation, magnetic  agglomeration, and deep
 filtration. The main treatment operations employed in the
 finishing operations  include chrome reduction,  cyanide
 oxidation, sedimentation, and metal sludge filtration (Fig.
 4).

 Treatment Technology

   The cyanides oxidation to cyanates (CNO-) or carbon
 di&xides (CO2) by various oxidizers (alkaline chlorination
 or hypochlorite)  has been accomplished for this industrial
 liquid  wastes.  Bioxidation  is  effective but  generally
 susceptible  to shock  loads and requires  a long residence
 time. Cyanide removal by ion exchange columns is effective
 but expensive.
   The phenolic wastes can also be removed by either liquid
 extraction or vapor recirculation but these methods are not
 very  economical. The bio-oxidation of phenols is being
 widely used and is economical.
   Effective  methods  of ammonia  recovery and removal
 require  the use of  an  ammonia still  and  gas  liquid
 adsorption.  Biological nitrification-denitrification of ammo-
 nia  is not  feasible currently because of inherent system
 instabilities. However, I will discuss this process later in the
 paper. The ion exchange removal approach looks promising
 but little  has been done.

 Disposal  of Spent Pickling Solutions

   The simplest method is neutralization but this unfortu-
 nately leaves a great deal of dissolved solids. Ion exchange
 removal has been demonstrated for sulfuric (JUSCM) and
 hydrochloric acid (HCL). Direct crystallization  of FeSO*
 from either  sulfuric or FeCU from hydrochloric liquors is
'possible. The  acid is regenerated in the process and the
 entire procedure  looks  promising.  Finally, spent pickling
 solution separation by reverse osmosis is now only a matter
 of speculation.

 Industry  Description

   Approximately ninety-two  percent  (92%)  of the  1972
 total  United States annual steel production was produced
 by fifteen major steel corporations. (See fig 5)
   Molten iron for subsequent steelmaking operations is
 normally  produced in a blast furnace. The blast furnace
 process consists essentially of charging iron ore, limestone,
                                                     25

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and coke into the top of the furnace and blowing heated air
into the bottom. Combustion of the coke provides the heat
necessary to obtain the temperature at which the metallurgi-
cal reducing  reactions take place.  The  function  of the
limestone is to form a slag, fluid at the furnace temperature,
which combines with unwanted impurities in the ore.
  The blast furnace auxiliaries consist of the stoves in which
the blast is preheated,  the  dry dust catchers in which the
bulk of the flue dust is recovered, primary wet cleaners in
which  most of  the  remaining flue dust  is removed by
washing  with water,  and  secondary cleaners  such  as
electrostatic precipitators.
  The  principal steelmaking methods in use today are the
Basic Oxygen  Furnace (BOF or BOP), the Open Hearth
Furnace, and the Electric Arc  Furnace.
  The  steelmaking process consists essentially of oxidizing
constituents, particularly carbon, down to specified low
levels (less  than  1%) and then  adding  various elements  to
required  amounts as determined by the grade of steel to be
produced (Fig. 6 shows hot slab and Fig. 7 continuous hot
forming of steel  tubing).
  The  open hearth furnace  allows the operator, in effect to
"cook" the steel  to required specifications.
  Since the introduction in the United States of the more
productive  basic oxygen process, open hearth  production
has declined from a peak of 93 million kkg in 1956 to 32
million kkg in 1971. The basic oxygen furnace is now clearly
the major steelmaking process.
  The electric-arc furnace (see Fig. 8) is uniquely adapted to
the production of high-quality steels. Practically all stainless
steel is produced in electric-arc furnaces. Electric furnaces
range up to 9 meters in diameter and produce from 1.8  to
365 kkg  per cycle in 1.5 to 5 hours.
  Although electric-arc furnaces have been small in  heat
capacity  as compared  to  open  hearth or basic oxygen
furnaces, a trend towards larger furnaces has recently
developed.  Electric-arc  furnaces are the principal steelmak-
ing process utilized by the so-called mini steel plants which
have been built since World War II.
  Now,  I  would like  to discuss two biological-chemical
treatments  that can be applicable to  steel manufacturing
wastewaters;  namely:  A)  ammonia  stripping  and,  B)
denitrification.
A. Ammonia Stripping
  In the air stripping process for ammonia removal,  four
considerations are most significant: 1)  pH of the wastewa-
ter, 2) rate of gas transfer, 3) the air-to-liquid requirements,
and 4) the  hydraulic loading.
  In a wastestream, ammonium ions  exist in equilibrium
with ammonia:

NHUOH  NH3 + H2O

Below a neutral pH of 7, only ammonium ions (NHt) in true
solution  are  present while, at  values greater than 12,
ammonia (NHa) exists in solution as a dissolved gas. In the
range of pH 7 to 12, ammonium ions and ammonia gas  exist
together  in equilibrium. As the  pH of the wastewater is
increased above  7, the  equilibrium shown  in the equation
above is  shifted to the right in favor of ammonia gas which
can be removed from the liquid by agitating the wastewater
with air additions. The relative percentages of ammonium
ions and ammonia as a  function of pH  and temperature are
presented in Fig. 9. Examination of this Figure illustrates
why very little ammonia stripping can be expected  in a
biological system. Even at the optimum temperature arid
maximum percentage of ammonia in the form of strippable
gas (NHs) is only about 25 percent.
  After the ammonium ion has been converted to ammonia
gas, there are two major factors which affect  the rate of
transfer. They are: 1) surface tension of air-water interface
and, 2) the difference between the ammonia concentration
in the  water and in the surrounding air. It  has  been found
that the surface tension is at a minimal value during the
process of forming water droplets,  and after the water
droplet has been formed, gas transfer becomes negligible.
Therefore,  repeated  droplet  formation,   rupture,  and
reformation greatly assist ammonia stripping operations
with regard to minimizing surface tension.
  Minimizing the concentration  of ammonia may be
accomplished by circulating  large quantities of air rapidly
through the water droplets. These same principles of droplet
formation  and reformation and the necessity of large
gas/ liquid  requirements are  inherent  in  conventional
cooling tower design and explain the" adaptability of these
towers  to the ammonia stripping process. The material
value can be  described as
Where:
  G   =  Quantity of air flow, moles incoming air/ unit time
  LQ  =  Quantity of water  flow, moles incoming water/
         unit time
  YI   =  Concentration of ammonia in air at the bottom of
         the tower,  moles ammonia/ mole air
  Yz   +  Concentration of ammonia in air at top of tower,
         moles ammonia/ mole air
  Xi   =  Concentration of ammonia in water at the bottom
         of the tower, moles ammonia /mole water
  Xz   =  Concentration of  ammonia in water at top  of
         tower, moles ammonia/ mole water
  This equation  is based on a mass balance of input and
output and  is valid regardless of the internal conditions
which  control  the  process.  Fortunately,  the internal
equilibria are governed by Henry's Law for which adequate
knowledge  exists and which will  not be described. The
molar  ratio of  ammonia in the gas and liquid remain
constant  at a specified temperature and pressure.
Design and Operational Considerations
  Very few ammonia stripping towers have been designed
for treatment of wastewaters; generally, those towers which
have been  constructed  were the for  treatment  of low
strength  municipal  wastewaters.  The  same  principles
utilized in the design of conventional cooling towers are also
applied to  the design of ammonia-stripping towers. The
crosscurrent design is the more prevalent.  Although the
counter-current  type may become popular as more field
data become available.
  There  is greater  efficiency of ammonia  removal with
increased depth  of tower  packing. It  should be noted that
the minimum air/ liquid  loading required  to obtain 90
percent removal  is approximately 2,000 liters of air per liter
of wastewater. The increased removals at greater depths are
probably due to  the greater  number of droplet formations
and the subsequent air-water  contact afforded by the greater
depth of packing.
                                                      26

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  Deeper tower packing shows little effect of hydraulic flow
rate, at less  than 100 L  min/m2, at hydraulic loadings
greater than  100, sheeting of the water is observed which
decreases the number  of  droplet formations and subse-
quently reduces the tower efficiency.
  Aside from economic considerations,  the major advan-
tage of ammonia stripping over other methods of ammonia
removal  is the ability to control  the level  of ammonia
removed in the process. Disadvantages are also inherent to
the air stripping process as outlined below:
  1. Cold weather operation
     a.  Ammonia solubility greatly increases with lower
        temperature
     b.  Inability to operate tower at wet bulb temperatures
        less than 0°C
     c.  Fogging and icing problems
  2. Deposition of calcium deposits within tower from pH
     adjustment with lime.
  3. Air pollution problems.
  4. Ammonia  reaction  with  sulfur  dioxide  to  form
     aerosols.
  5. Deterioration  of  wood  packing due to high pH of
     wastewaters.
  In the case of industrial  wastes where the ammonia
concentration of the wastewater may be extremely high, on
the  order  of several  thousand mg/1,  an  air  pollution
problem may develop.  Other potentially troublesome
problems may develop near large metropolitan areas or
other regions in which high concentrations of sulfur dioxide
form an aerosol or fog. In light of the above disadvantages,
ammonia stripping  is  a  practical, reliable  method for
nitrogen removal under the right climatic conditions and
with the proper  precautions regarding scale prevention or
removal.

B. Nitrification-Denitrification
  In the destruction  and assimilation  of organic com-
pounds,  biological organisms will  require,  as nutrients,
approximately 1 kg of nitrogen per 23 kg of BOD removed.
In  estimating  nitrogen  removal  through a  system  by
synthesis, only the BOD removed and not that applied
should be considered.  The nitrogen which is removed by
synthesis is  incorporated, at least temporarily, into the
microbial cell, and is eliminated by removal of excess sludge
from the system. A system with poor settleability properties
cannot be expected to demonstrate a total removal of 1 kg
of nitrigen per 23 kg BOD due to the high carry-over of
organisms  in the  effluent.  In  this case, mixed media
nitration may be  required to achieve the desired effluent
quality. Also, if the system has an excessive detention time
or  over 6-8 days  sludge  age, nitrogen in the form of
ammonia or organic nitrogen may be released back into
solution so  that once  again an assumed removal  of 1
kgN/23 kg BOD removed would not be valid.
  During the process of biological nitrification, ammonia
and some organic nitrogen  forms are converted to nitrite
and nitrate  compounds by  a  specific  set'of organisms,
Nltrosomonas and Nitrobacter. These organisms are strictly
aerobic autotrophs, i.e., they obtain carbon from inorganic
sources such as COa, HCO3, etc., and do not employ the
same metabolic  mechanisms as  those  organisms which
assimilate  BOD  materials.  The nitrifiers reproduce  and
grow at  much  lower rates than the BOD  removing
organisms and thus compete in the same environment. For
example,  in  an  activated  sludge  system  a  constant
concentration of organisms or suspended solids (MLVSS) is
desired, so that all excess  sludge which  is produced and
accumulates is periodically wasted. If the BOD removing
organisms are producing at a rapid rate, they will increase
the required wastage of sludge from the system, which will
generally be much higher than the wasting rate compatible
with maintenance  of an adequate population of nitrifiers.
Thus, insufficient nitrification will result unless the wastage
rate is lowered to accommodate the nitrifier requirements.
The wastage  rate  is  usually controlled to maintain a
sufficient, "sludge age" in the system  for  nitrification.
  It is claimed that a sludge age greater than 4 days in the
activated  sludge  process  is  adequate  for  90  percent
nitrification at 20° C.  I caution you that this information
was developed for municipal wastes  and should never be
applied to higher strength  industrial discharges  without
extensive pilot studies.
  Biological  nitrification of  ammonia concentrations  as
high as 500 mg/1 with greater than 90 percent removal can
be obtained with the single-stage activated sludge process.
Two-stage systems have achieved greater than 97 percent
removal with these high influent levels. The  biological
process can be applied to high as well as low concentrations
of ammonia  assuming proper conditions of pH, tempera-
ture, absence of inhibitors, etc.
  The nitrifiers are biological organisms, and are subjected
to the same constraints which limit most biological systems,
i.e., temperature, toxicity, shock loading, pH, etc. Nitrifica-
tion has generally been found most efficient in the pH range
of 7.8 to 8.3, and pilot results have indicated that inefficient
nitrification systems can be improved by adjusting  the
influent pH level so that the  aeration  basin contents  are
within the  optimum range.  Sodium  hydroxide is recom-
mended for the  pH adjustment since lime may precipate
calcium carbonate and limit the system from the standpoint
of  available inorganic  carbon,  particularly  with high
ammonia wastes. Lime may be satisfactory for low-strength
ammonia wastewaters.
  Compounds toxic  to  nitrifiers  include  heavy metals,
cyanides, halogenated  compounds, phenols,  mercaptans,
and thiourea. Trace amounts of these constituents may not
nullify nitrification, but could lower the rate coefficient, kn.
Pilot  studies would then be required  prior to design  or
"washout" because retarded growth rate may occur  in the
final system.
  Optimum temperature for nitrification has been cited as
28-32° C with nitrification  ceasing below 5°C. If severe
temperatures are  anticipated  (less than 12-15°C in  the
aeration basin), then serious consideration should be given
to the feasibility of nitrification. It is possible to preheat the
influent wastestreams, but this is not a practical  solution
with most large streams.
  Nitrate and nitrated compounds are very difficult to treat
by  physical  and  chemical techniques  other  than  ion
exchange.  However, ion exchange technology for nitrogen
compounds is applicable to a small percentage of wastewa-
ters. Consequently, biological mechanisms remain the most
practical and dependable methods for removing nitrate
constituents from wastewaters. Biological nitrate reduction
can  be accomplished  by  assimilatory  or  dissimilatory
mechanisms.  Assimilatory reduction  occurs when nitrate-
                                                       27

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nitrogen is utilized as a source of nitrogen for synthesis by
initial conversion to ammonia and subsequent incorpora-
tion  into the cell. Nitrate dissimilation involves biological
oxidation  of organic compounds where nitrate serves as the
terminal hydrogen acceptor in place of molecular oxygen.
The end product of this reaction may be nitrite, ammonia,
nitrous oxide or nitrogen gas depending on the organisms
and  the   pH of  the  system.  Practically,  the  anaerobic
denitrification process  will oxidize  degradable  organic
carbon compounds and reduce nitrate to harmless nitrogen
gas.
  The denitrification process has been effectively applied to
nitrate levels as  high  as 10,000  mg/1.  Currently, three
denitrification systems, anaerobic activated sludge, anaer-
obic ponds, and  upflow anaerobic filters  offer good reli-
ability with  variable economy. If  the nitrate treatment oc-
curs after BOD removal, there may be insufficient carbon
present for reduction of the nitrate and an external source
will be required. Methanol has been most commonly cited
as the most economical external  carbon source based on
cost  and  available carbon.  Carbon addition,  whether
methanol  or a suitable industrial  waste, is required for all
denitrifying  systems which follow organic removal proc-
esses. In  many instances, particularly in those with high
strength industrial wastes, the economy of the system will
depend  on the external carbon source chosen..
  With many industrial processes, e.g., where nitric acid is
employed in-plant, it is much more desirable to pretreat the
waste for  nitrate reduction ahead of a BOD removal system,
such as activated sludge. In this manner, readily-available
carbonaceous BOD in the  raw  waste  is utilized  for the
denitrifying carbon source. This concept not only reduces
the costs  for external carbon  in a post-treatment scheme,
but  will also reduce the subsequent aeration volume and
                          Figure 1. The Nation's Top 10 (1)
horsepower needed for the activated sludge system due to
the BOD reduction through  the denitrification system.
  Besides  ammonium stripping and denitrification, some
other technologies to be implemented in the near future
include: slag and sludge dewatering and disposal, technol-
ogy development for a closed loop in an interested steel mill
reducing phosphates  and heavy  metals, employment  of
electro-membranes in  the HiSO4 pickling  operation  to
achieve a step towards  closed cycle,  and  finally  a new
technology is emerging using direct reduction of low grade
taconite ore effectively eliminating the  blast furnace and
coking operation to achieve  total environmental control.
  All  of  these  aforementioned technologies will   be
attempted  in   the  near  future  by  the  Environmental
Protection Agency to improve the steelrnaking industries'
technology and to preserve the integrity of the United States
waterways.
                    References

1. Lacy, W.J., G. Rey and H.G. Keeler, Projects of the
   Industrial  Pollution Control  Division,  U.S. Environ-
   mental  Protection  Agency,  Office  of  Research and
   Development, Washington, D.C. 1974.
2. Cywin,  A., E. Dulaney, Development  Document for
   Effluent  Limitation  Guidelines for  the  Steel Making
   Segment of the Iron and  Steel Manufacturing Point
   Source Category,  USEPA, Office of Water and Hazard-
   ous Materials, Washington, D.C., June  1974.
3. Adams,  C.E., W.W.  Eckenfelder,  Process  Design
   Techniques for Industrial  Waste  Treatment," Enviro
   Press, Nashville, Tennessee,  1974.
4. Lacy, W.J.  Point Source Control—EPA Industry R&D
   Cooperation, Chemical Technology, Vol. 5, pp. 742-747,
   December  1975.
5. Pollution   Abatement  Costs  and  Expenditures  1973.,
   U.S. Department of Commerce, MA 200(73)-2,  Issued
   3/19/76
                                                                                  ; NATIONAL
                                                                                     STEEL
                                                                                 CORPORATION
                                                        28

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Figure 1. Steel Production Processes (2)

Table 1 United States Annual Steel Production  Major Producers
                          (2)  1972
United States Steel
Bethlehem Steel
Republic Steel
National Steel
Armco Steel
Jones and Laughlin Steel
Inland Steel
Youngstown Sheet and Tube
Wheeling Pittsburgh
Kaiser
McLouth
Colorado Fuel  and Iron
Sharon
Interlake
Alan Wood
Metric Tons/ Year
        31,750,000
        19,960,000
         9,980,000
         9,520,000
         7,710,000
         7,280,000
         6,800,000
         5,440,000
         3,540,000
         2,720,000
          1,819,000
          1,360,000
          1,360,000
           907,000
           907,000
                                                                   8 BIRLEC 50 Ton Electric Arc Furnace at Manchester Steel
                                                                   Inland Steel Company's highly automated slabbing mill can handle
                                                                   ingots weighing as much as 55,000 pounds .  . . either singly or two
                                                                   in  tandem.  It  can  roll  the top,  bottom,  and  both edges
                                                                   simultaneously resulting in better, more uniform grain structure
                                                                   and increased yield.
                                                           i
                                                           Z
                                                       HX)
 Figure 3. Distribution of Ammonia and Ammonium Ion with pH
   and Temperature (3)
                                                                    Fig. 7 I.acleda Steel's Six  Stand Horizontal/Vertical  Forming &
                                                                    Welding Mill
                                                               29

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Fig. 3 Inland Steel's 80 inch Five Stand Cold Rolling Mill and
Pickle Line.
Facilities  Improvement  for

Biochemical  Treatment  of
Petroleum  Refinery
Wastewater.
V.Ya.  Gerber

Bashkirian  Scientific Research  Institute of
Petroleum Refining (USSR)

Summary

  This paper presents estimated performance specifications
for designing biochemical treatment facilities at refineries
and petrochemical plants.
  The choice of single- and two-stage treatment systems for
refinery and petrochemical sewage is recommended depend-
ing on the quality of the sewage.
  There are provided some operational  data for refinery
and petrochemical sewage treatment  and advanced treat-
ment  as well as  the flow  diagrams and  structures  of
activated sludge units used. The advantages of activated
sludge units over biological  filters and those of two-stage
systems  over single-stage systems are  demonstrated.
  The quality of biological sewage treatment effluent and
the ratio of dilution for it to be harmless for receiving water
is reported.
  In the Soviet Union biochemical treatment is one of the
basic  treatment  processes preceding the refinery  waste
discharge into receiving waters.
  The biochemical  treatment has widely been used  for
treating refinery wastes.  Treatment  facilities  of  all  the
petroleum refineries and petrochemical plants situated in
the Volga and Urals basins include biochemical treatment
plants. The latter plants are  foreseen  for all  the petroleum
refineries and petrochemical plants under construction.
  Refinery  wastewater can  be  subjected to  biochemical
treatment  either alone  or  diluted  with  domestic  and
chemical wastewaters. In  the first case biogenous elements,
especially nitrogen and phosphorus, are to be added to the
wastewater.
  The biochemical treatment equipment of Soviet refineries
is mainly presented by activated sludge systems, especially
those  with  a  many-point waste  feeding and a complete
mixing.  Most  commonly conventional  activated sludge
units (with  a one-point waste and activated sludge feeding
to the  first channel of the unit) are used at the second
treatment step.
  As a matter of fact, no  use is made of biological filters for
oil-containing waste treatment  at the Soviet refineries, as
the operating experience at a refinery has shown them to be
insufficiently efficient,  BODs, oil, and phenols removals
being  as low as 73, 29, and 72%, respectively. The use of
activated sludge units at the same refinery has improved the
BOD, oil, and phenols removals up to 93 to 95%, 80 to 84%
99 to  100%, respectively.
  Oxidation ponds  at domestic refineries  only serve for
after-treatment of a biochemical treatment effluent.
  As  the   laboratory  investigations  and  the  operation
experience have shown, the treatment efficiency of two-step
facilities is  by  10 to 15% better  in comparison  to that of
single-step  facilities,  in  terms  of  both  BOD and oil
removals.  The  operation  of  two-step  facilities creates
conditions  stimulating  adaptation  of  the  second-step
activated sludge microorganisms for uptake of difficult-to-
oxidize substances. Therefore, most petroleum refineries use
a two-step biochemical treatment. The treatment efficiency
of these facilities for oil-containing wastewater is as follows:

BOD  removal    93 to   98%
oil removal      77 to   86%
phenols removal 99 to 100%

The same result can be  achieved in single-step activated
sludge units by increasing the total aeration duration by 30
to 35%.
  Special investigations have shown that only about 20% of
ether-soluble  substances contained   in  a  biochemical
treatment   effluent   are  hydrocarbons  originated  from
petroleum,  the remaining substances being decomposition
and oxidation products  which do  not undergo complete
biodegradation.
  Thus, petroleum  hydrocarbons account for 2 to 3 mg/1
out of 8 to  12 mg/1 of ether-soluble substances in a refinery
biochemical treatment effluent.
  The  operation data has shown that when using two-step
biochemical treatment of refinery wastewater in activated
sludge units and an advanced treatment in oxidation ponds
the following composition of the final effluent is obtained:
 COD, mg Q2/1
 BODS, mg Q2/1
 Ether-solubles
 Oil
 Phenols
 60 to 80
   2 to 8
   4 to 8
   1 to 2
0.0 to 0.002
   Thus, the use of a complete biochemical treatment of re-
 finery wastewater followed by its advanced treatment makes
 it possible to  minimize the amounts of pollutants to be
                                                     30

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discharged to  receiving waters.  However,  a long-term
wastewater treatment in activated sludge units, big volumes
of  facilities  and  a  high  electric  energy  consumption
stimulate the search of intensification ways for lessening this
process capital and operation costs. Therefore, investiga-
tions  are  carried out in  the USSR  to intensify the
biochemical wastewater treatment  process  in  activated
sludge units, to  reduce their  aeration duration,  and to
diminish the facilities sizes and treatment costs.
  The intensification  of  biochemical  treatment  of oil-
containing wastes is possible by raising the activated sludge
and  dissolved  oxygen  concentrations as well as by the
facilities hydrodynamics improvement.
  For a process with high sludge  doses most suitable are
integrated  facilities  (aero-accelerator  type) which are
equipped  with  pneumatic mechanic aeration systems and
are combined with a settler. The combined  construction of
facilities makes it possible to achieve maximum treatment
efficiency with low space requirements. The oxygen quantity
fed into the facility can be changed by changing automati-
cally the aerator rotation rate. The use of flotators instead
of secondary settlers makes it possible to increase the sludge
dose  in an activated sludge unit. Thus, at a petroleum
refinery a two-step plant for biochemical treatment has been
tested, with a  flotator  provided for  the first step sludge
separation. Due to the flotator it is possible to maintain a
higher activated sludge dose in the activated sludge unit.
However, during aeration using air  the intensified biochemi-
cal oxidation at high activated sludge doses can give rise to
anaerobic conditions in the activated sludge unit, which
adversely  affects the  treatment  process.
  The aeration using technical oxygen  instead of air is a
promising method to intensify the process of wastewater
biochemical treatment. The performed investigations have
shown the replacing  of air with  technical oxygen to be
capable of shortening the aeration duration when treating
oil-containing wastewater by a factor of 4 to 6 and to lessen
accordingly the  volume   of  activated  sludge  units in
comparison to conventional air aeration or to increase their
capacity.  The  replacing  of air  with  technical  oxygen
dramatically raises the dissolved oxygen concentration in a
facility. Good oxygen regime in an activated sludge unit
makes it possible to  increase the activated  sludge dose.
  Changing from air  to oxygen  for aeration results in
considerably better properties of the activated sludge: little
or no thread bacteria, no swelling, and improved settleabili-
ty.  Therefore,  suspended  solids in a secondary clarifier
effluent do not  increase  in  spite of  increasing sludge
concentration. Also, the use of technical oxygen contributes
to nitrogen and phosphorus removals.
  The substitution of  technical oxygen for  air  requires
special design reactors: tight, with mechanical mixing of
sludge liquor and oxygen reuse.
  Two types of facilities destined to using technical oxygen
have been developed in the USSR:  countercurrent aerotank
- a clarifier with airlift circulation and oxytank - a tight
aerotank with mechanical aeration, combined with sludge
separator.  In  the  oxytank   the  efficiency of  oxygen
utilization achieves  95%.  New design biooxydizers are
adapted for operating with high sludge doses of  10  to 15
g/1, which, along with increasing oxygen concentration up
to 8 to 10 mg/1, raises the oxytank oxydation capacity up to
5 to 10 kg BOD'otai/m' day. The  oxytank was tested for
chemical plant wastewater under semicommercial  condi-
tions.
  Technical and economical calculations have verified the
profitability of using oxygen  for wastewater biochemical
treatment.  The use of oxytanks for industrial wastewater
treatment is most profitable when oxygen is supplied by air
fractionation departments of industrial plants.
  The wastewater  biochemical  treatment  equipment is
persistently improved  to  enable  an advantageous  use  of
oxygen even in  those  cases when it is to be  produced
specially for wastewater treatment.
  In recent years, much emphasis has been placed  on the
hydrodynamics improvement of aeration facilities.
  In the Soviet Union and abroad various types of activated
sludge units are widely used. Their basic types  include
completely  mixed  and plug  flow systems  as well  as
intermediate types.
  According to  the  theory of chemical reactors and  the
theoretical analysis of kinetic models used now for organics
biochemical  oxidation in  activated  sludge units,   the
oxidation degree of starting materials in a completely mixed
activated sludge systems (for a zero order reaction) is above
that in a plug flow activated sludge system at equal facility
volumes. However, the  practice of treating wastewater has
shown the  completely mixed activated sludge system to be
superior  to other systems in many respects, for the most
part in that it contributes to a fail-free performance at an
immediate  concentrated wastewater influent. Therefore, the
completely-mixed activated sludge  system as well as  that
with a many point wastewater feed (intermediate type) have
found wide application for petroleum refining wastewater
treatment.
  Large-scale  flow  studies in various types of activated
sludge systems have shown the flow conditions of even long
conventional  plug  flow activated  sludge systems  to
approach those of complete mixing. Thus, various types of
large-scale activated  sludge systems achieve essentially the
same efficiency.
  Laboratory and   pilot data  have shown  a specially
designed activated sludge system to perform more efficient-
ly than a conventional one, which allows a 1.5 to 2-fold
reduction in the facility volume.
  Thus,  the use of  combined facilities with high  sludge
doses, specially designed activated sludge systems,  and
technical  oxygen instead of  air  makes  it possible  to
considerably intensify the biochemical treatment process for
petroleum  refining wastewater- and to reduce capital and
operating costs.
  Quality requirements for waste discharge into receiving
waters are  now stringent both in  the Soviet Union and
abroad. This makes  it reasonable to subject biochemically
treated  petroleum  refinery  wastewater  to an  advanced
(tertiary) treatment such as filtration; treatment improve-
ment, the use of such methods for a biochemical treatment
effluent leads to  diminishing sizes of biochemical treatment
facilities.
                                                        31

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Biological  Methods  for
Control  of Nitrogen  in
Municipal  Wastewaters
William  A.  Rosenkranz*
* Director, Waste Management Division
Office of Research and Development
Environmental Protection Agency
Washington, D.C. 20460USA
  Various compounds containing the element nitrogen are
becoming increasingly  important  in wastewater  manage-
ment due to the many effects that nitrogenous materials in
wastewater can have on  the  environment.  Nitrogen, in
various forms, can  deplete  dissolved oxygen levels in
receiving waters, stimulate aquatic growth, exhibit toxicity
toward aquatic life, affect  disinfection  efficiency, present a
public  health hazard and affect the suitability of wastewater
for reuse.
  Biological  and  chemical  processes which   occur in
wastewater treatment plants and in the natural environment
can change the chemical form in which nitrogen exists. Such
changes may eliminate a deleterious effect of nitrogen, while
producing, or  leaving  unchanged, another effect.  For
example, by  converting ammonia  in  raw wastewater to
nitrate, the oxygen-depleting and toxic effects of ammonia
are eliminated, but the biostimulatory effects may not be
changed significantly.
  Most of the nitrogen in  raw municipal wastewater  is
usually in the ammonia form, although 30 percent to SO
percent  is  normally  associated   with  organic matter.
Nitrogen  is  removed  in  various  ways  in wastewater
treatment facilities. A large portion of the organic nitrogen
is  removed by primary sedimentation, while  additional
amounts of organic nitrogen may be biologically converted
to ammonia when the wastewater is subjected to secondary
treatment such as activated sludge. Nitrates and nitrites
usually absent in raw wastewater, may be present following
a  highly efficient  secondary treatment process  and the
presence of signigicant numbers of nitrifying bacteria.
  Effective methods  of wastewater treatment  which will
remove nitrogen are increasingly needed in many locations
where  critical water quality conditions exist. Governmental
agencies  have promulgated effluent standards  relating to
water  quality in  an  attempt to relieve or prevent the
symptoms of nitrogen pollution in such locations. Scientists
and engineers have  devoted considerable research  and
development effort toward developing both biological and
physical-chemical methods for nitrogen removal in order to
produce  effluents which can be discharged  into streams
which  require such action for achieving acceptable water
quality.
  Physical-chemical methods which have been shown to be
effective  depending on effluent quality requirements in-
clude:

   1. Breakpoint Chlorination—Addition  of chlorine to
     wastewaters for the purpose of oxidizing the ammoni-
     um ion to end products composed predominately of
     nitrogen gas.
  2. Selective Ion Exchange for Ammonia Removal—Use
     of an ion-exchange  resin  which  is selective for
     ammonium. A natural zeolite, clinoptilolite, occurring
     in the Western United States has been found effective
     for this purpose.
  3. Air Stripping of Ammonia—Countercurrent circula-
     tion  of large  volumes of air and  effluent through a
     stripping tower after the  treated effluent has  been
     adjusted to high pH.

  Biological methods of removing nitrogen, the subject of
this  paper, consist of two wastewater treatment phases:
nitrification and denitrification. The processes which have
been used  for this purpose utilize several configurations, but
all  involve first  the nitrification  step,  followed  by  a
denitrifaction step.  Certain controlling factors form the
basis of configuration selection. Nitrification by autotropic
bacteria (Nitrosomes  and Nitrobacter) achieves a maximum
rate in the activated sludge process at dissolved oxygen
concentration of about 2 mg/1 or above. The rate decreases
to zero as the dissolved oxygen concentration decreases to
zero. While denitrification by facultative bacteria occurs in
both anoxic and slightly  aerobic systems, the most rapid
denitrification occurs with dissolved oxygen concentration
of zero. Ample sources of readily acceptable organic carbon
to serve as an energy supply for the bacterial reduction of
the nitrate and  nitrite are  required.
  In biological  treatment of  wastewaters, oxidation of
carbonaceous material, nitrification, and denitrification all
occur within  a  single process if sufficient bacterial solids
retention time is provided for development of the nitrifying
and  denitrifying organisms. Optimum process  operating
conditions for oxidation and for subsequent denitrification
are thermodynamically antagonistic. The presence of the
more powerful oxidant  oxygen (electric acceptor)  sup-
presses the use of NOa (electron acceptor) in the biological
oxidation  of the carbonaceous material in the wastewater.
In  conventionally aerated biological  systems, efficient
oxidation  of the carbonaceous  and nitrogenous materials,
in either a single or  two-stage  process, is achieved under
aerobic reactor conditions. The aerobic conditions produce
the nitrate product, but also remove the organic materials
which act  as readily available electron donors for denitrifi-
cation. In addition,  the  dissolved  oxygen in the  water
significantly suppresses  or minimizes the biological reduc-
tion of the nitrate or nitrite as they are produced.
  Although the biological potential exists in municipal
wastewaters  for  both  nitrification and denitrification
without supplemental organic carbon sources, the operating
conditions usually employed in aerobic biological processes
produce efficient carbonaceous  removal and  nitrification
but  not  efficient  denitrification.   Thus,  the  operating
conditions for the activated sludge process must be selected
which will produce efficient nitrification and denitrification
with the indigenous  carbonaceous material in the waste-
water acting as  the electron donor during denitrification.
  Research to accomplish this objective was undertaken at
the EPA Pilot Plant at Washington, D.C.  The approach to
achieving  nitrification—denitrification in a single, activated
sludge reactor-clarifier with the wastewater organic carbon
used for  denitrification consisted  of  providing alternate
periods of aerobic and anaerobic conditions  within the
reactor and operating the reactor at sufficiently low food-to-
                                                       32

-------
 microorganism ratios (high solids retention times) to ensure
 a nitrifying population within the mixed liquor culture. To
 provide the alternating aerobic-anaerobic conditions while
 continuously operating  the air compressor, the activated
 sludge reactor was divided into two equal basins operating
 in series. Each  basin, with a water depth of 3.35 m(ll ft.),
 provided a detention time of 3.55 hr., at a process flow of
 189 cu m/day (50,000 gpd). Air was supplied alternately to
 each basin; first to one basin and then to the other on a 30-
 minute  cycle.  The dissolved  oxygen in the  basins  was
 manually controlled  at  between  2  and 3 mg/1 during
 aeration and rapidly decreased  to zero during the anaerobic
 period.
   Mechanical mixers in each  basin,  operated at 30 rpm,
 suspended  the  mixed liquor solids without any significant
 surface  aeration of the wastewater. Figure I illustrates the
 pilot plant configuration.
  Nine  months of test data are shown in Table I. During 9
 months of operation, the pilot plant operated at  a F/M
 (food-to-mass  ratio) of approximately 0.1  Ib BODs/lb.
 MLVSS/day (0.1 g/g/day) expressed on the basis of the
 total inventory  in the reactor. This F/ M was sufficiently low
 to permit the development of a mixed culture of organisms
 for carbon oxidation, nitrification and denitrification. Total
 nitrogen removal efficiencies  were  highest at the higher
 COD/TKN ratios.
  Nitrogen removals during the study varied from 54 to 84
 percent. As in  other alternating aerobic/ anoxic studies,  it
 was found  that a  severe filamentous  bulking condition
 developed  in  the  sludge, limiting  wintertime  clarifier
 overflow rates to about 12.24 cu m/day/sq m (300 gpd/sf).
 Bulking sludge  had  been observed during operation of this
 pilot study at low temperatures and at low F/M operation
 here and at other plants. It appeared that clarifier would
 limit operation  of this aerobic/anoxic system as it will other
 similar systems.
  On March 1, 1975, the Office of Research and  Develop-
 ment  funded a full-scale plant evaluation project of the
 above described process at Owego, New York. The plant
 operates over a range of wastewater temperature of 5°C to
 20°C. The objective of the project was to maximize nitrogen
 removal by simple changes in operational techniques.
  The plant is designed for 7,570 cu m/day (2 mgd) at the
 design date of 1990. Present flow averages 1,514 cu m/day
 (0.4 mgd), with a maximum dry weather flow  of 2,271 cu
 m/day (0.6 mgd) and a minimum of  1,135 cu  m/day (0.3
 mgd). The plant does experience the impact of infiltration
 since high flows of 3,406 cu m/day (0.9 mgd) have been
 recorded.  Facilities  consist of dual  primary  settlers and
 aerators (Figure II). Each reactor has two compartments
 and each  compartment  has  one  surface aerator.  The
 compartments are sized for contact stabilization; with the
 larger units having 15  horsepower and  the  smaller 10
 horsepower surface  aerators.  Dual final clarifiers are fitted
 with chain drags and scum baffles. Sludge is digested in a
 two-stage anaerobic digester. Sludge  is  hauled to  nearby
 farms and disked  into the soil.
  In line with our findings at the Blue Plains  pilot single
 stage system that a rather high  BOD/TUN ratio is  needed
for  denitrification, the Owego primary clarifiers were taken
 off line. The aerators received raw wastewater with a BODs
of approximately 200 mg/1 and a total nitrogen content of
approximately 40  mg/1.
                D.C. RAW WASTEWATER
                  PRIMARY
                   VL
     AIR ,
               i-'fc,  i
      NITRIFICATION DENTRIFICATION
                    REACTOR
           WASTE,
                      RETURN SLUDGE >v

                   SECONDARY
                   FINAL EFFLUENT
Figure 1 Blue Plains Alternating AnoxloAerobic System



I
*
FINAL
SETTLING
•4—
em n«i^>*^ ^
CONTACT +f

•- •*-•
' J
AERATION TANKS
SOUTH 1
                        Figure 2
                   Extended Aeration
               Water Pollution Control Plant
                Town of Owego, New York
                                                      33

-------
MONTH
1973
JAN

FEB

MARCH

APRIL

MAY

JUNE

JULY

AUGUST

SEPT

F M MISS
DET. l.B BOD APPLIED MG 1 SVI. COD
TIME I.BMI.VSS DAY <9j Ml. TKN
HR OR C G DAY VOLATILE) O RATIO
12.3

12.3

123

12.4

10.5

8.8

6.8

6.6

8.7

0.072

0.066

0.10

0.081

0.089

0.105

0.093

0.089

0.11

3510
(74)
3980
(73)
2950
(73)
3540
(67)
4170
(69)
4010
(69)
3040
(64)
3200
(57)
3700
(65)
245

250

330

277

227

188

133

134

_

9.6

9.9

10.5

10.6

10.0

10.3

7,9

7.5

10.0

INFLUENT QUALITY MG
TEMP..
C
14.0

14.2

15.5

--

—

23.0

25.0

25.5

26.0

BOD;
96.5

99

110

98.8

115

107

51

44.2

99

TOTAL
KJELDAHI.
SS NITROGEN
MO

108

128

120

109

112

153

197

110

25.7

. 23.2

24.8

21.7

23.3

24.0

15.0

14.9

22.6

1
BODi
20.4

14.0

6.5h

5.3"

3.3"

3.2"

3.8"

2.6"

7.2"

EFFLUENT QUALITY M« 1.
SS
15.4

14.3

15.0

13.0

11.8

7.8

9.0

10.0

16.0

TOTAL
KJELDAHI. NO)
NITROGEN NO:-N
2.28

1.52

4.20

5.20

1.36

1.51

2.14

1.23

I0.2C

3.99

4.41

2.30

6.03

8.25

2.3

2.72

3.74

0.22

REMOVALS.
BOD'
79

86

94"

95"

97*

,7b

93"

94"

93"

PLKtTM
TOTAL
SS NITROGEN
85

87

88

89

89

93

94

95

83

7*

75

74

49

39

84

68

67

54

 ,PRIOR TO FILTRATION
 t NITRIFICATION INHIBITED
 cAMMONIA LEVEL WAS 9.4 MG/L AS N (SEE TEXT)

Table 1   Summary of operation and performance for the Blue
Plains Alternating Aerobic/Anoxic System (Reference 60)
  After a brief start-up period, it was determined that the
plant was operating well and that conditions were suitable
for pulsing the surface aerators to encourage denitrification.
Again, on the basis of Blue Plains experience, a 50 percent
cycle was set for the initial period  of study. The  aerators
would  be on for 30 minutes and off for 30 minutes. The
project included plans to collect data during warm and cold
weather. The  warm weather data was collected up  to
September of 1975. The cold weather data collection period
was  scheduled to begin in January  of 1976.
  Performance of the Owego plant has been very good. For
the  period  through  September  of 1975,  BOD'   and
suspended solids removals were better than 90 percent, nitrification
was complete, and total nitrogen removals were in excess of 80
percent without the addition of an organic supplement. At times
total nitrogen removal approached 95 percent efficiency.
  This  project is  nearly  complete. The cold  weather data  is
undergoing analysis. Based on  the on-site experiences, the process
appears to be relatively easy to operate.  It has been observed that
Nocardia growths have not appeared during the report period. We
expect that  the process could  be made to operate automatically
with  the proper sensors to monitor the  effluent  for the degree of
nitrification and/or denitrification required.
  As mentioned earlier,  there are several processes or process
configurations that can be used for nitrogen removal. The Pasveer
ditch, or endless channel system can  be effective in  removing
nitrogen.  Removals of 90  percent have been reported. This system
is illustrated in Figure III.
  EPA funded an evaluation project of this type of system at
Dawson, Minnesota. The Dawson plant  is designed to treat 984 cu
m/day (0.26 mgd) having a strength of 230 mg/1 BOD5 and 200
rug/1 suspended solids. One of the objectives of the study
was to determine the feasibility of nitrifying and denitrifying
the wastewater without the addition of an alternate carbon
source (for denitrification).
  Nitrification-denitrification efficiency  is  linked to  the
concentration  of dissolved  oxygen  in the channel. In the
zone that  experiences  a D.O. of greater than 0.5 to 1.0
mg/1, nitrification will  occur. In the zone where D.O. is less
than 0.5 mg/1, denitrification will  take place without the
addition of an alternate carbon source such as methanol.
Instead,  the  raw  BOD  acts  as the  carbon  source.
Denitrification is limited by the ratio of BOD (or COD) to
TKN. The higher the ratio the more efficient"the process.
  Even though the  plant was not operated in the most
optimum mode, removals ranged from approximately 50 to
80 percent. As stated earlier, the Dutch and others have
reported removal of nitrogen in excess of 90 percent.
                       .RAW WASTEWATER
                                        ROTOR OR OTHER
                                        AERATION SYSTEM
                              EFFLUENT
Figure 3 Pasveer ditch or Endless Channel System for nitrogen
removal

Figure IV shows two additional  systems,  one of which
utilizes methanol as a carbon source.
  The   advantages  and   disadvantages  of  the  several
biological  nitrogen  removal  systems  are summarized in
Table II.
                                                          34

-------
 INFLUENT
WASTEWATER
                                INFLUENT
                              WASTEWATER
             I RETURN SLUDGE
        ANOXIC*
     DENITRIFICATION
      TANK (4 HR)
        AEROBIC
     COMBINED CARBON
       OXIDATION-
      NITRIFICATION
         TANK
         (18 HR)
        ANOXIC
     DENITRIFICATION
      TANK (5 HRl
         I
   AEROBIC TANK 12 HR)
    SEDIMENTATION
        TANK
        (I HRl
                                   COMBINED CARBON
                                     OXIDATION-
                                    NITRIFICATION
                                        TANK
                                       (10 MR)
                                   INTERMEDIATE
                                   SEDIMENTATION
                                    TANK (4 HRl
                                   OENITRIFICATION
                                     TANK (2 HR)
                                       1
                                  AEROBIC TANK (1 HRl
                                      FINAL
                                   SEDIMENTATION
                                    TANK (4 HRl
                                  4—
      DENITRIFIED
       EFFLUENT

    A. BAROENrHOfROCESSRIHRI
                                     DENITRIFIED
                                      EFFLUENT
                                   B. ALTERNATIVE METHANOL
                                    BASEO SYSTEM 121 HR)
Figure 4 Comparison of Denitrification Systems
SYSTEM TYPE
•MIMA*UI iguui»i« *
AIIMHIBCHDMINKdlVWIlt
tiWICW MANOl rOLlDHIMC


CWIMtdCMtllNgit-
OINliniMCMigilN ttlt-
rtNdlO GMWIH •I4CIIIII
UIMG III 01164 *OU1
CIHIDNfOuNCI
DAIIO* MHNIHCAIIO*
tUtHMDIOGAOMt*
C*IUI>« UilHCI


ADVANTAGES
ci*uufttiMAiia»i*titiivui 0*l««iiOH
1 ICIHMI IHIHOl g 110*1 ID* ttlr'CAM If f ASH .
mconoPOHAUD
fAtHPHOCIMIH IHf IVtllMCM II «f»P»*THT
OfllUKIO
HlbHOKHIIUf NllHOtlN KIUOVII nilllll
OlMaHtlHAUO llAtlLIIV OF OnilMIOtt
oatuou
If m llWITAIIDNt l» rMAIMI HI -IiaulMCI OMHUll
OMiMiriD
HVMIIHAIiai RIOUIfllD

kllll«lltfMIMQ( UWMrNDCIKIffliauiHie




DISADVANTAGES
t,Mf *>f R NUMII N U» UN>I f HOlltUt
mouiMiDiOHMirHiMCAiiaii at
NITMIXCAIIDN IHAN IN CUMIIHIQ
1T1IIWI
icciuMtrHiNot amoinoHMociH
m ouiRinron mt«tnc«tio«« •

eiMURIMtfcllOMIIAIfSWfllTtOW
Hi rMAMOt itiiotrsriM
milt)" 0) OM««TIQH L1NN(0 TO
ClAHIflf ft 1 Oil IIOMASi III ruRM
!«i »mn*r » autNti a* HDDS
LMIIIOWHIMIOIH DJkllO P
HIMOVAi RfOUlRtO
Nor*«iicitanMovibie(o*
MirRlfUAliJlCAlNlT ItRiCANII
BtfflCtlLl tOOHMltt NllHiPictflOW
•ttVOINtlMlflCAIiOllfOMalllf
0«mifllMC*tlONH*l(1LU« l»«(,l
ITNlKTUIMiniQUIIMO
UfTHADUl IASIO tVirfM
CIMlf If * f OK IIOHASS Ml TURD
UUOCI IVIKING
IDCAIMflllSlaufMCI O^TIDIIt
LIUITID WHIM 10 TH H AMD t
•[MOVAl RiauiHtO
NtTRIMIHSAGAIHIT TORICAMrl
BIHICUirTOOrHMIHHIllllMCAllOII
MDDINItMIHtAIIDIIimilUtlV
Table 2. Comparison of Denitrification Alternatives
                     References

Bishop,   D.F.,   et   al,   Single  Stage  Nitrification-
  Denitrification,  Environmental Protection Series, EPA
  670/2-75-051, June  1975
Grounds, Harry C, Draft Final Report Dawson, Minneso-
  ta Demonstration Project, U.S. EPA Grant No. 803067-
  01-1, December 1975
Personal Communication  w Donald E. Schwinn (Stearns
  and Wheler Civil and Sanitary Engineers), May 6,1975 in
  reference to  Owego,  New  York/EPA Demonstration
  Project: Full-Scale Operation of a Single-Stage Nitrifica-
  tion-Denitrification  Plant
Schwinn, Donald E., Quarterly  Report  on Single-Stage
  Nitrification Denitrification  Full-Scale Study at Owego,
  New York,  EPA Project S-803618-01, July  1975
Process  Design  Manual  for  Nitrogen  Control U.S.
  Environmental Protection Agency, Technology Transfer,
  October 1975
                                                         35

-------
     Operation  Experience  of

                  Oxytanks


Skirdov,  I.V.,  Shvetzov, V.N.,  Bondarev,
A.A., Lurje, B.J., Bereykina, N.G., Katchko-
va,  S.E.

  The Institute VODGEO has developed a construction and
a system  design method  for carrying  out  the biological
wastewater treatment process of high intensity by using both
pure oxygen and high concentrations of activated sludge.
The system is termed "an  oxytank".
  The oxytank system affords achieving a high efficiency in
supplied oxygen utilization, a significant reduction in total
structural  volume due to a combined action of biological
oxidation  process and mixed liquor separation in the same
structural  volume as well as it  enables  to  promote the
automatically controlled system for oxygen supply propor-
tional to quantity and quality of influent wastewater.
  The oxytank (Fig. 1) involves a cylindrical container inside
of which a hermetically sealed reactor is positioned. (2) The
reactor is provided with the surface tyrbo-aerator (5) driven
in rotation by an electric  motor located on the cover. The
rotary  hydraulic valve enables  the aerator shaft  to  be
hermetical. In the annular space between the reactor and the
outside wall of the container a sludge separation tank (3) is
installed where activated sludge - treated water separation
has taken  place. The middle part of the partition separating
the reactor is equipped with ports with directed tangential
nozzles  (7) and with gates for mixed liquor delivery to the
sludge separation tank from the reactor. The activated sludge
is returned to the reactor via the annular aperture (8) in the
lower part of the partition.
  Thus in order to promote the intensification of  sludge
separation and  to prevent  the unwanted sludge  deposits
settling at the bottom  of the sludge separation  tank the
mixing device is mounted in the form of grid with rods of 30-
50 mm in diameter. The scrapers (6) are hinged in the lower
part of grids. The wastewater is passed to the reactor through
the pipe (I) and it is mixed with activated sludge by means of
the aerator (5) then the mixed liquor is saturated with gas
that  is under the reactor cover.  The oxygen is fed to the
reactor through the pipe (9) equipped with automatic valve
actuated by a pressure sensor. (12) The treated wastewater is
introduced simultaneously with activated  sludge  to the
sludge separation tank via the nozzles under the action of
speed head developed by the aerator. The clarified liquor is
withdrawn through  the annular collecting gutter (4). The
settled activated sludge is" returned to the reactor through the
annular aperature (8).
  The given concentration of dissolved oxygen  in the
reaction chamber  is  maintained automatically.  As the
oxygen is being consumed by the mixed liquor the pressure of
gaseous mixture in  the  reactor over  the  liquid surface
decreases,
  At that moment the pressure sensor (12) gives a signal for
opening the valve located  on the pipe (9) through which the
oxygen is fed. The oxygen starts to be introduced into the
system. When the gaseous mixture pressure in the reactor
achieves the set level the valve automatically closes.
  Gradually accumulated respirated carbon dioxide formed
during the biochemical oxidation process as well as nitrogen
stripped from the  wastewater and also  inert gases being
supplied simultaneously with pure oxygen have  changed
gaseous mixture composition in the reactor. In this case the
partial pressure of oxygen reduces while that of carbon
dioxide and of other components increases. The decrease of
oxygen partial pressure results in the oxygen concentration
reduction in the mixed liquor and hence for the stabilization
of gaseous mixture composition in the reactor it is necessary
periodically to  remove the accumulated  gases by blowing
the oxveen throueh thp sv«tpm
  As  the  partial pressure of oxygen in gaseous  mixture
drops below the set level the dissolved oxygen concentration
sensor (11) gives a signal for opening the automatic valve
(10).  The  gaseous mixture  from  the working chamber
is released into atmosphere. The oxygen is fed to the reactor
through the pipe (9) instead of being withdrawn from the
gaseous mixture.   As  the set level of dissolved  oxygen
concentration in mixed liquor is  achieved the valve  (11)
closes,
  On the basis of pilot plant investigations in oxytank it the
method has been developed for estimation of the above type
of treatment works capable to operate in a regime of reactor
with complete mixing.
  The wastewater retention time in oxytank reactor may be
determined by the  following equation
                     t=  Lo ' Lt
                          KozKseCsc                 (1)

     where t - average retention time for wastewater in
              oxytank reactor, hrs;
          Lo  -  influent wastewater BOD fed  to oxytank,
              mg/1;
          Lt - effluent wastewater BOD, mg/1;
            -specific oxygenation rate at Cu = 3 g/1 and at
             oxygen concentration of 2 mg/1.
        Koz - coefficient  with  regard  for  the effect of
              dissolved oxygen concentration on specific
              oxygenation rate;
    K sludge  - coefficient  with  regard  for  the effect of
              activated sludge concentration on specific
               oxygenation rate;
    'Csludge  - activated sludge concentration, g/1. ,

  The value  of coefficients of both Ko2 and Ksiudge were
experimentally  defined and  Figs  2  and  3 yield  the
corresponding curves.
   The sludge separation tank design is based on determina-
tion of ultimate hydraulic load.  In the course of investiga-
tions performed at the Institute VODGEO it was defined that
the effect  of the  assumed hydraulic load on the sludge
separation tank as a function of dimensionless criterion of
1C.
where I -  sludge index value, sm2/g;
      C - activated sludge concentration in solution, g/cm3.
   The curve in Fig. 4  represents this relationship. To
improve the treated water quality the sludge separation tank
is designed to be operated in a regime of settling tank by use
of suspended solids.  Special means in oxytanks allow the
depth of suspended solids beds to be stabilized and ensure its
exchange.
   One of the oxytank features is a high oxygen concentra-
                                                      36

-------
 tion in the mixed  liquor supplied to the sludge separation
 tank from the reactor. Significant store of dissolved oxygen
 in recycling zone of sludge separation tank combined with
 favourable hydrodyanamic  operating  conditions  create
 provisions  for intensive biochemical  process in the zone.
 The total  volume  of oxytank may be divided  into  several
 zones  depending on performed  functions (Fig. 5).
 Figure 1. - Scheme of oxytank
        \
                                         * cona»atrttloa (/I
Figure 2. - Coefficient Ku VS activated sludee concentration
	 ».-
fi

'
16
<
10
<\i





A
I



/





^r



o • e; «

^




^^
**~ \
\










t *o. a* i
                                         .
                dissolved oxygen concentration, ng/1

Figure 3. - Coefficient Km VS dissolved oxygen concentration
                                                                 If


                                                                 o.»

                                                                v__
                                                                 0,6
'hi








*t


i


\

!


;
V
\
O
>






\
0 0



—


0 oo
» <
\



-



•*
l 0
o







>
' ^^*>







>J







•* -.


0,5 0,4 ,£W tf> 0,7 Qf O,S $0
3C
                                                                 Figure 4. - Hydraulic load acting on sludge separation tank of
                                                                 oxytanks VS  dimensionless parameter 1C.
Figure 5. - Scheme of oxytank divided into the following process
zones:

I.  Reactor - biochemical oxidation and mixed liquor saturation by
   oxygen.
2.  Recycle zone of Sludge separation tank - biological oxidation
   and mixed liquor separation.
3.  Zone of suspended solids filler water treatment by filtering and
   oxidizing the organic compounds.
4.  Protective zone.
                                                            37

-------
  The given scheme shows that the largest part of sludge
separation tank volume in oxytank fulfils two functions
such as  thickening  of mixed liquor and  biochemical
oxydation.  The  total structural volume  is  considerably
reduced due to this fact.
  The  experimental  oxytanks  at  wastewater treatment
works of Schekinsk Combine "Azot" have been constructed
and were put into operation in 1974. VNII VODGEO has
recommended the  oxytanks be designed  on  the  basis of
investigation of a  pilot plant with a capacity of 150-200
m3/day.
  The oxytanks of volume  270 m3 a 9.6 m in diameter each
have been built at Schekinsk Combine "Azot". The following
values of estimated parameters for oxytanks are presented
below:

  1.  Oxygenation  capacity  (OC),  BODcompi.  -  2.04
     kg/m3/day Oxygenation capacity (OC), COD - 2.73
     kg/m3/day
  2.  Wastewater flow rate - 59 m3/hr (at influent waste-
     water  BOD of 300 mg/1)
  3.  Effluent BOD compi. -  15 mg/1
  4.  Effluent suspended solids  - 15-20 mg/1

  In order to define the actual technologic data and the
sanitary  efficiency  of  oxytank  operation the  Institute
VODGEO in cooperation with the laboratory of treatment
at Schekinsk Combine "Azot" as well as with Tula regional
and Schekinsk sanitary-epidemologic stations have consist-
ently observed these treatment works.
  The average compared data of both oxytank and aeration
tank operation through   a  long  period  of service are
summarized in Table I.
  As shown in the given  results, the oxytank generation
capacity was close to that estimated and exceeded 3.5 times
the  Oxygenation  capacity of  full-scale  aeration  tanks
operating in parallel at Schekinsk Combing "Azot". In this
case  the removal  efficiency of main components  from
wastewater was in accordance with the complete biological
treatment.
  The oxytank operating efficiency doesn't practically vary
at its long  overload  evaluated by organic impurities.  So
through the period  of operation from March 1, to March 6,
1976 with average  duration of flow retention time  of 3.9
hours in reaction zone the oxytank oxygenation capacity
was equal to 3720 g COD m3/day. Over this period of time
the oxytank ensured the wastewater biological treatment to
be complete. Effluent BODcompi. was not higher than 15
mg/1, COD averaged 77 mg/1 and suspended solids were
maintained in amounts of  22 mg/1. With a nitrogen initial
content stripped from ammoniated  salts  at a dose of 73
mg/1 in effluent ammoniated nitrogen observed in amounts
of 29.8 mg/1 on average.
  It should be noted  that oxytank short overloads that are
1.6-1.9 times as much as the estimated  loads  have  no
adverse effect on the effluent quality.
  As evidenced by  the oxytank operation data which show
that at the same extent of treatment the sludge index value
in oxytank can be decreased 1.4-1.6 times compared to that
in aeration tank.
  The  efficiency of  oxygen  usage  that  is  supplied to
oxytanks was not below 80% and averaged 93-96%.
  Attention was  attracted to a high concentration of
ammoniated nitrogen in oxytank effluent as a result of
insufficient process has taken place.
  Both efficient and economical advantages of oxytanks
usage may be illustrated as  an  example for wastewater
treatment at plants of nitrogenous industry.
  For economical  comparison the treatment works have
been taken in the following combination:
Example I - Aeration tanks with air supply by compressors.
Example  II-  Combined hermetical  aeration tanks (oxy-
  tanks)  with oxygen supply from air separation installa-
  tion at the  industrial plant.

  The mechanical wastewater treatment works and sludge
disposal plants in the given examples were accepted to be the
same and because of this they are neglected in calculations.
  The  examples  are  compared  by using the biological
treatment plant efficiencies in the of 50,000-300,000 m3/day.
  The  treatment  works are designed so that  complete
biological treatment is ensured.
  To determine the estimated parameters of aeration tanks
for wastewater treatment the following performance data are
used:

  Influent BOD     - 300 mg/1
  Effluent BOD       15 mg/1
  Aeration time     - 16 hrs
  Sludge dose      - 1.5 - 3 gr/1
  Aeration intensity - 4-5 m3/m2/hr

  In oxytank calculations the retention time adopted to be
3 hours (including retention time in sludge separation tank
of half an hour). An increase in oxytank capacity is caused
by rise of both sludge dose up to 10-12 gr/1 and dissolved
oxygen concentration up to  12-14 m/1.
  Technologic data from the above are considered that the
compared examples are summarized in Table II.

insert table

  By determining the capital expenditures for oxytank at
wastewater treatment  the oxygen accepted to be supplied
from air  separation installation. In this  case the capital
investment have been denned by specific investment based
on  cryogranic  plant  cost  that  amounted  to  303  rou-
bles/m3/hr.
  By estimating energy consumption using mechanical type
aerators  in oxytank the specific rate accepted to be equal
                      0.32kw.hr
                       kg(02)
with regard for an increase in aerator  capacity and  a
decrease  in energy cost respectively, therewith the oxygen
was  dissolved due to partial pressure elevation of this gas.
  Technical-economical calculation results are summarized
in Table  III.

Conclusions

  1.  The oxytank construction is manufactured on reactor
complete  mixing  principle  and most applying  to the
wastewater treatment. The considered  system is character-
ized  by a high efficiency of oxygen utilization, by reducing
the construction size  associated  with  this fact that  three
processes such as settling, filtering through activated sludge
                                                      38

-------
suspended  solid  bed  and   biochemical  oxydation  are
combined in  a  sludge separation tank, as well as  by
automatic  control  system  for oxygen  supply that  is
proportional   to  organic impurities  quantity  fed  with
wastewater.
  2. Full-scale plant studies  showed that the technologic
data  related   to  oxytank performance agreed  with the
estimated results.  In this case oxytank oxygenation capacity
is 3.5 times higher compared to that for aeration tank at
 complete biochemical treatment of wastewater as concerns
 of the basic components.
   3.  The pure oxygen utilization  affords the  activated
 sludge concentration in oxytank to be maintained in 6-10
 g/1 range at high  dissolved oxygen concentration of 10-12
 mg/1. In so doing the settling properties of activated sludge
 are improved.
   4. Oxytank system provided for a high quality of treated
 water at short overloads by 1.6-1.9 times  and at long ones
 by 1.3-1.4 times.

Table I
Average Month
Parameters


1. Estimated aeration
time, hrs
2, Activated sludge
concentration, g/1
3. Dissolved oxygen,
mg/1
4. Sludge index, sm3/g
5. Removed BOD, %
6. Oxygenation capaci-
ty, g COD/ m3/ day
7. Load effect on
sludge, g COD/g day
Wastewater
8. COD, mg/1
9. BODcompi. mg/1
10. Ammoniated nitrogen
11. Nitrite nitrogen, mg/1
12. Nitrate nitrogen, mg/1
13. pH
Treated water
14. COD, mg/1
15. BODcompi., mg/1
16. Ammoniated nitrogen,
mg/1
17. Nitrite nitrogen, mg/1
18. Nitrate nitrogen, mg/1
19. Suspended solids, mg/1
Data
Aeration
tank

20

2.5

3-4
90
97.4

743

298

663
487





45
13




20
Table II Technologic data

Example Capacity Removed
BOD
1000
m3 t/day t/day
50 18.8
I 100 37.6
200 75.2
300 113.8
SO 18.8
II 100 37.6
200 75.2
300 1 13.8
Duration
Aeration Settling


hr hr
16 1.5
16 1.5
16 1.5
16 1.5
3.0 1.5
3.0 1.5
3.0 1.5
3.0 1.5


Oxytank

5.5

7.8

12
66
97.4

2610

335

663
497





65
13




18
taken from
-
Average Week
Data
Aeration
tank Oxytank

20 3.9

2.5 7.4

3-4 12
73


965 3720

302 503

686 686
512 512





48 78
13 13

29.8


20 22
the examples I and II
Volume Gas rate
Aeration Settling Air Oxygen
tank
1000
mj
45.0
90.0
180.0
270.0
8.4
16.8
33.6
50.0
tank
1000
m3 m3/hr m3/hr
4.2 70,000
8.4 140,000
16.8 280,000
25.2 420,000
4.2 - 708
8.4 - 1416
16.8 - 2832
25.0 - 4248
                                                        39

-------
  S. The distinguishing feature of oxytanks is elimination of
wastewater volatile components discharged into the atmos-
phere that prevents it  from being  polluted by  harmful
substances. At the  same time  if ammonium nitrogen is
present in wastewater influent in large amounts because of
lack of stripping the ammonia, the  ammonium nitrogen
content in oxytank effluent was higher than in aeration tank
one.
                         6. Technical-economical evaluation obtained for the case
                       of wastewater treatment of nitrogenous industry showed
                       that the oxygen utilization  in oxytanks  proved  to  be
                       advantageous from an economic point of view. Therewith
                       capital  investment for biological  treatment works are
                       reduced by 1.5-2 times, operating expenditures are decreased
                       by  1.4-1.6 times and economical effect for  plants with
                       capacity of 50,000-300,000 m3 of wastewater per day was
                       177,000-625,000 m'/year respectively.
                                                               Table HI

Examples






I
Aeration
tanks

II
Oxytanks


Capacity of
treatment
plant

1000 m3/day

50
100
200
300
50
100
200
300

Volume
of aeration
tanks or
oxytanks
1000m3

45.0
90
180
270
8.4
16.8
33.6
50.0

Air or
oxygen
rate

1000 m'/hr

70
140
280
420
0.71
1.42
2.73
4.25

Capital
Aeration tanks or
oxytanks

Unit
roubles/ m3

20.4
15.9
14.1
13.0
31.0
21.5
21.5
21.5

Total
1000
roubles
920
1430
2530
3510
260
362
723
1120
cost

Air flowing and
oxygen

Unit
roubles/
m'/hr
-
-
-
-
303
303
303
303
plants

. Total
1000
roubles
150
190
240
260
215
430
860
1290

General
K


1000
roubles
1070
1620
2770
3770
575
792
1583
2490
            Operating costs
                  Amortization charges
          Energy cost
            Construction  Equipment
               3.9%        5.
Total     Unit    Per year   General
Biochemical   Compared Economical
 treatment   expenditures effect
1000
roubles
per year
36.0
55.7
98.5
137.0
10.1
14.3
28.2
43.7
1000
roubles
per year
7.9
10.1
12.7
13.8
11.4
22.8
45.6
78.4
1000
roubles
43.9
55.8
111.2
150.8
21.5
37.1
73.8
122.1
roubles
1000m3
-
-
-
-
16.9
16.9
16.9
16.9
1000
roubles
per year
257
512
1024
1540
178
356
712
1070
1000
roubles
per year
300.9
567.8
1135.2
1690.8
199.5
393.1
785.8
1192.1
roubles
1000m3
16.5
15.6
15.5
15.5
6.1
5.9
5.9
5.9
1000
roubles
per year
464
784
1505
2183
280
703
981
1540
1000
roubles
per year
.
-
-
-
177
266
475
625
                                                       40

-------
Improvements  for Kraft Pulp

and Municipal  Treatment

Processes
Frank P. Sebastian
Senior Vice President
Envirotech Corporation
Menlo Park, California

Dennis S. Lachtman
Assistant to the Senior  Vice  President
Envirotech Corporation
Menlo Park, California


Introduction

  The opportunity to reappear before  such a distinguished
group of Soviet and American scientists is indeed an honor.
As  the title suggests, my comments  will  be directed to
process improvements in bleached  kraft pulp mills, and in
the  municipal  sector  to  solids  processing  and  water
monitoring. While I am not a paper expert, I am pleased to
have this opportunity to present this development.
  The pulp and paper industry, which has been a major
contributor to both water and environmental degradation,
now has some new developments  that promise to reverse
this trend.  The Salt  Recovery Process in conjunction with
the closed-cycle bleached kraft mill, which will subsequently
be discussed in depth, can serve as  either a modification of
existing facilities or an entirely new flowsheet for new or
existing facilities. The closed-cycle bleached  kraft  mill
avoids the  cost of both secondary and tertiary treatment
processes because it recycles materials and eliminates the
need  for treatment  while both saving the costs of  new
materials and reducing water consumption.
  In the municipal process area, but certainly not limited to
such  applications, the Hi-solids filter and control systems
based  on the TOC  analyzer represent modifications  that
both enhance treatment efficiency and reduce expense.
  The Hi-solids filter increases sewage sludge solids content
which allows for greater energy recovery while maximizing
furnace handling capability.
  The TOC analyzer is a proven useful resource for quick
effluent and  influent  monitoring  and has been used to
increase plant performance through a strategy  of feedfor-
ward  and   feedback  control. Where  previous  carbon
analyzer technology  was  susceptable  to fouling or shut-
downs, new developments have all but eliminated these
maladies.

Closed-Cycle  Mill
One of the industries traditionally having problems with
effluent streams has been the pulp and paper industry,
which in the United States has recently experienced some
costly  and difficult years  dealing with environmental
control. According to Chemical Weekd), the paper and pulp
industry paid an unprecedented $1 billion (0.756 billion
Rubles) for pollution control last year. As the pulp and
paper industry  effluent streams approach zero  discharge
requirements in the United States, these costs promise to
escalate further under present  technology.  Regardless of
which country, be it the USSR or the USA, such large kinds
of expenditures put a strain on production  capacity.
  Fortunately, there is a new and emerging process for the
kraft  pulp  industry  that promises  to  eliminate  both
contaminated effluents and the needs for external advanced
waste treatment facilities. This process also reduces the cost
of raw chemicals. The processes I am referring to are called
the closed-cycle mill and  salt control  processes  and were
first developed by W.H. Rapson and D.W.  Reeve in their
research  efforts at the University of Toronto<2,3).  Erco-
Envirotech, a joint venture of American and  Canadian
business interests, continued the development of the closed-
cycle concept for commercial applications.
  The closed-cycle mill combines a number of innovative
procedures providing  a  process  design  that  eliminates
effluent discharges  through internal recycling. The system
also recovers fibers, chemicals, organics and heat normally
lost to external treatment systems in conventional  kraft
mills.
  Recognizing the obvious merits of this system a Canadian
firm, Great Lakes  Paper  Company, has installed the first
closed-cycle  bleached  kraft pulp  mill in Thunder Bay,
Ontario,  Canada<4). The  plant  will enjoy  the  economic
benefits  to  be had from  eliminating waste  treatment
facilities, yet it will be the world's first pulp mill not to
discharge contaminated effluents. The only effluent from the
plant will be clean cooling water.  Among the advantages
that the Great Lakes Paper Company's mill will have are <5>:
  1. water consumption will only be 1/6 of previous levels;
  2, substantial energy savings associated with heat recycle
     and water  use reduction;
  3. lower raw  chemical consumption;
  4. improved pulp yield, strength and brightness; and
  5. elimination of need for external treatment.

Kraft Pulping and Bleaching
  Before  proceeding to discuss the closed-cycle kraft mill
with the  Salt Recovery Process, I would like to digress  a
moment  to review the basic concepts inherent  to  kraft
pulping.
  Kraft or sulfate  pulping is a process that treats wood
chips with a strong alkali solution during cooking, as shown
in Figure 1. The alkali solution penetrates  the wood and
dissolves  the lignin. After cooking and washing, the end
product is pulp.
  The  afkali  solution, called  white  liquor, consists of
sodium sulfide (NazS) and sodium hydroxide (NaOH). The
sodium sulfide (Na2S) serves to both speed the reaction and
strengthen the  pulp. Toward  the  end of the cook, the
physical integrity of wood chips is weakened and they can
be blown from the digester under pressure.  The  fibers are
easily blown apart by  steam expansion and the resultant
dark-colored product  is  a very strong  pulp,  hereafter
referred to as unbleached kraft pulp.  The liquid fraction
remaining after the cook is black and it contains more than
half the   original  wood  content  in  addition  to  spent
chemicalstj).
  The kraft process must recover this black liquor to be
economically  efficient.  The box marked "Black  Liquor
Evaporator" in  Figure  1  is where  the black liquor, after
                                                     41

-------
being washed from the brown pulp in the preceding box
marked  "Brown Stock  Washing" is  concentrated  via
evaporation. The concentrated black liquor is burned in a
furnace and the remaining smelt is dissolved in water. This
solution contains sodium carbonate (NaaCOa), and sodium
sulfide (NazS) and is referred to as green liquor. The sodium
carbonate (NazCOj) is then causticized  with lime. This last
step is schematically shown in Figure 1  as occurring in the
box marked "Liquor Preparation." The resultant solution,
which is clear and called white liquor, is reused for pulping.
  The kraft mill is not a major pollutant process, as 95% of
the  chemicals are continuously  reused in the described
flowsheet.  However, the  brown-colored  pulp  is  not  as
desirable nor does it command as  high  a price as bleached
pulp.
  Early attempts to bleach brown pulp with chlorine (Ch)
and caustic soda led to substantial strength losses. However,
bleaching with chlorine dioxide (ChO), chlorine (Ch) and
sodium hydroxide (NaOH) make it possible  to get pulp
brightness  of 88-92%  G.E. without losing pulp  strength.
This development which was also pioneered by Dr. Rapson,
led  to a large worldwide expansion of  kraft pulp produc-
tion<5).
  The  bleaching plant  contributes the major pollutant
burden from  bleached  kraft  mills. Bleaching  dissolves
another 7-10% of the pulp which in combination with spent
chemicals and toxic compounds like chlorophenols com-
prise the bleaching plant effluent. Since this effluent can be
very toxic, the closed-cycle bleached kraft mill concept is a
significant  development,  both  economically and environ-
mentally.   I will  be  discussing  the   detailed  economic
advantages of the closed-cycle mill in a following section.
The Process at Great Lakes Paper Company
Thunder Bay,  Ontario, Canada
  The plant scheduled to start up late this year will produce
250,000 tons (227,000 metric tons) per year  of bleached
market grade pulp. Many of the process techniques for this
plant have either been demonstrated or are being used in
mills throughout the world today. Those process techniques
already used elsewhere and contained in the Thunder Bay
flowsheet are the following^:

  1. Countercurrent washing in the bleachery:
  2. high chlorine dioxide substitution for chlorine in  the
     first bleaching stage;
  3. steam stripping of contaminated condensate; and
  4. a closed screen room; and
  5. spill tanks to accommodate temporary process upsets
     and allow subsequent recycle.

  The unique  aspect of the Thunder Bay  flowsheet is  the
total recycle of bleachery effluent,  as shown in Figure 2, to
the  unbleached portion of the mill. Normally,  the problem
with such a recycle procedure would  be  the  build-up  or
introduction of sodium chloride, which must be removed at
the  same rate it is introduced. To remedy the situation, the
Erco-Envirotech SRP (Salt Control Process) System will be
used.

Salt Control Process
  The SRP System is schematically represented in Figure 3.
Basically,  the  process uses white liquor from the liquor
preparation section of the mill and treats it in a two-stage
evaporization and crystallization procedure where sodium
chloride  is purified  for  reuse and sodium  carbonate
(NazCCb) and sodium sulfate (NaSO,») are recycled back to
recovery and recausticizing.
  The white liquor fed  into stage  one is 2-3%  by weight
sodium chloride (NaCl) and 10-11%  by weight consists of
sodium hydroxide (NaOH) and sodium sulfide (Na2S). As
shown  in  Figure  4,  a triple  set of evaporators  using
backward feed concentrate the liquor to approximately 26%
by weight sodium hydroxide (NaOH) plus sodium sulfide
(Na2S). All three evaporators are forced-circulation units
having external heat exchangers. The final liquor tempera-
ture is between 250 and 260°F(6).
  In the evaporators,  sodium carbonate (NaCOj) and the
double salt burkeite (NazCOs^NaiSCh) will crystallize out
of solution. A clarifier removes  these crystals and a rotary
vacuum drum-filter further dewaters these crystals. Most of
these crystals are  recycled to the liquor preparation  or
recausticizing section and a small quantity is sent, as needed,
to the furnace for the purpose of reducing sulfates (SO4) to
sodium sulfide (Na2S). The filtrate from the rotary vacuum
drum filter  is recycled  back to the first evaporator.
  The concentrated liquid leaving the clarifier in step 1
enters  an evaporator-crystallizer in step  2  and is further
concentrated to approximately 36% by  weight sodium
hydroxide (NaOH) and sodium sulfide (Na:S). At this point
most of the sodium chloride crystallizes out of  solution.
  The sodium chloride (NaCl) crystal slurry enters another
clarifier unit where a concentrated white liquor is removed.
This white  liquor contains only trace quantities  of sodium
chloride  (NaCl), sodium carbonate (NasCOs) and sodium
sulfate (NazSOij, but  has all the active alkali for pulping.
The stage 2 clarifier underflow is pumped to another rotary
vacuum drum filter for crystal  dewatering. These crystals
are  further purified via  an agitated leach tank, where
residual  amounts  of  sodium  carbonate (Na2COa) and
burkeite (Na2CO3-2Na2SO*) are  dissolved. The slurry is fed
to a horizontal vacuum belt-filter,  where  a countercurrent
washing process yields a better than 99%  pure sodium
chloride (NaCl) cake.  As will be mentioned later, the pure
sodium chloride (NaCl) cake can serve as a raw material for
the manufacture of chlorine dioxide (ClOa) in the bleaching
process or  it may be used as a resource having an average
selling price of 0.64
-------
  I.  Salt Control Process:
  2.  counter current washing;
  3.  high  substitution  of chlorine dioxide  (CIO:) for
     chlorine in the first stage of the bleachery;
  4.  steam stripping of condensate; and
  5.  closed screen room and spill tanks that accommodate
     process upsets;  and
  6.  recycle of all bleachery effluent within the mill.

  The total savings from operating costs which are in excess
of $5,000,000  (3,785,000 Rubles) are  approximately one-
half the capital costs. Additionally, these statistics exclude
such factors as the  value  of salt (NaCl) recovered  or the
potential value of heat that could be recovered from the
clean cooling water make-up. The value of the salt (NaCl)
for a 900  TPD (818 metric tons/day) plant would be
$224,000 per year (169,344 Rubles/year). The value of heat
recovery would vary depending  on the climate, but would
be of greatest value in colder climates like those characteris-
tically found in many parts of Russia, where such thermally
enriched waters can be used for  building heat.  Appendix 1
contains the detailed analyses for the cost savings statistics
as contained in  Figure 5.
  Recent statistics for the Thunder Bay installation show
that  the 250,000 ton per  year (227,000 metric tons/year)
facility  (Figure 6)  will  save  approximately  $4,000,000
(3,024,000 Rubles) annually(g). This saving  originates from
modifications that improve its performance over a conven-
tional mill in the following areas:

  I.  Reduction of fresh water usage from 25,000 (95 cubic
     meters/1000 kg)  to  4,000  gallons  per ton (64 cubic
     meters /1000 kg) of pulp,
  2.  net energy savings of 5,000  Ibs. (2500 kg) of steam per
     ton (1000 kg) of pulp, and
  3.  savings from reduced consumption of raw chemicals.

  Since the differential cost of this closed-cycle and that of a
conventional mill  is $8,000,000 (6,048,000 Rubles), the
payback or break even period is approximately two years.
Whereas  conventional primary, secondary  and  tertiary
wastewater treatment facilities do not normally bring in a
return of economic benefit to the plant, the closed-cycle mill
with  the  SRP  System, which  is less  costly  than these
external waste  treatment systems, has the advantage of
paying for itself within a  remarkably  short time period.
  According  to the  Environmental  Protection  Agency
(EPA>9), the 1975 U.S. production capacity for all kinds of
pulp was 96,000 metric tons per day. The largest single pulp
process used is the kraft  process, which produced 72,379
metric tons per day or 75.4% of the U.S. pulp supply in
1975. The  EPA reports that kraft pulp mills  will  need to
spend  $895,000,000  (677  million  Rubles) to meet best
practical technology (BPT) and $732,000,000  (553  million
Rubles)  for  best  available technology   (BAT)  effluent
guidelines as required by  the EPA
-------
TOC Analyzer

  Another innovation that, can be  used  for  improving
municipal treatment efficiency is the  total organic carbon
(TOC) analyzer. The  importance of this instrument has
increased in the United States since recognition of the link
between trace organics and cancer in humans. Accordingly,
sewage  treatment  facilities  are starting to place more
emphasis  on reducing  organic and trace organic effluent
streams loadings.
  Whereas BODs  has been and should remain  a  useful
indicator of water quality, the TOC measurement gives a
more detailed and rapid assessment of organic loadings that
can be used to modify and  optimize treatment efficiency.
While BODs measurements take five days to complete, TOC
data is ready in a matter of minutes. Measurement of total
organic carbon at various points in a treatment plant can
provide timely and valuable operating information. This is
especially true when operating activated sludge processes.

Optimization of Sludge Treatment
  The TOC  analyzer is  an effective test for controlling
activated  sludge  processes. The TOC can be  used to
implement two popularly used design  approaches for
activated  sludge  systems.  The  first  uses a  food to
microorganism (F/M)  ratio and relies on the observation
that  the  amount  of  biodegradable  organics applied to
biological  systems  affect the  microorganism  metabolic
rate.   In  their
technique, SRT is the  inverse of the biological growth rate.
The  SRT is espoused  as a  comprehensive basis for
biological design because all process variables can be related
to it. The SRT process is controlled  by sludge  wasting.
  While opinions  may vary as to  the  efficiency  of using
either or both the F/M ratio or the  SRT process control
strategy, TOC measurements apply to both process control
strategies.
  TOC measurement might be taken in the activated sludge
process at various stages (see Figure 12). For example, using
the TOC values from  raw sewage and  comparing this to
TOC values after primary treatment can  be used to  evaluate
the effectiveness of the primary  settling  process.
  The collecting of samples at  either  of the above  two
points poses problems in  regard to  representative or truly
random sampling. To alleviate these difficulties, laboratory
models  use  blenders  and  homogenizers.  For treatment
plants using on-line  measurements,  commercial  grade
grinding pumps homogenize  the sample particles before
analysis. In either case, good TOC analyzers are specifically
designed to handle such samples.
  The mechanisms for TOC feedforward and feedback
control  strategies  would  be  implemented after  making
various  changes depending on  the design characteristics
being followed.
  For example, F/M  ratio control  can be effected by
measuring TOC for primary effluent,  TOCpRi,  and for
return activated sludge, TOCRAs. The F/M ratio can then
be calculated as follows:
F_
M
  Primary Flow (Vol/Time x
  TOX PR1 (Wt/Vol)
  RAS FLOW (Vol/Time x
  TOCRAS (Wt/Vol)

= Wt. of Primary Organics
      Wt. of RAS Organics

  Adjustment  of RAS flow can be applied to maintain a
constant F/ M ratio. Sludge retention time can be controlled
by regulating the sludge inventory of the plant since,
SRT =
   Biological Mass in System
   Biological Mass wasted/time
  TOC measurement of mixed liquor leaving the aerator,
TOC MO and TOC RAS can be used in combination with plant
volumetric data to calculate the organic mass in the system.
This data can then be utilized to adjust the plant wasting
rate.
  Alternately,  TOCpRi -  TOCsEc (TOC of secondary or
final effluent) can be used to calculate the quantity of new
sludge made. This data can be used to adjust  the plant
wasting rate and thus  utilize SRT control.  This technique
assumes that (k) is constant  in the following relationship:

        New Sludge = k (TOCpRi - TOC SEC)

  Finally, TOCsnccan be employed as a final indication of
plant  effectiveness. While the quality of effluent water from
a waste treatment plant is usually evaluated by the BODs,
TOC  values are an  equally useful monitoring tool. If the
effluent  TOC  values  are   maintained  as low  as  are
economically feasible,  the BODs values will also be as  low
as are economically feasible.

The Hillsboro Story
  Although many  sewage  treatment  plants  use TOC
analyzers to monitor and  aid in optimizing  their treatment
efficiency,  one  case  stands  out  above the  rest as  an
illustrative testimony for the TOC analyzer. This example
involves the Hillsboro, Oregon Waste  Treatment Facility
that was  put  on line in March  197 luj).  Due to high and
varying organic loadings from the local food industry, the
Hillsboro plant was operating below the effluent standards
set forth by Oregon's Department of Environmental Quality
(see Figure 13).  At times the wastes from local industries
comprised  75%  of  the plant's organic  loading.  Organic
loadings have and will vary up to 50%.
  In July of 1973, a new strategy was initiated which relied
upon  fast measurement and control of key plant variables.
The   following  measurements  routinely  measure  and
controlled for were the following:

  1.  F/M ratio,
  2.  respiration  rate of aeration tank effluent,
  3.  5-minute settling of aeration tank effluent, and
  4.  dissolved oxygen in  aeration tank.
The adjusted parameters to improve performance efficiency
were:

  1.  returned sludge flow,
                                                      44

-------
  2.  waste sludge flow,
  3.  sludge conditioning time, and
  4.  aerator air flow.

  The results of this new strategy have proven extremely
successful.  Figure  14  shows  that the Oregon plant  had
BODs average from 20-90mg/ liter prior to adoption of the
new strategy. Following institution of the new strategy, the
plant was able to consistently meet the  Oregon  effluent
standards as the  BODs dropped to between  10  and 15
mg/ liter on  a monthly average (see  Figure 14).
  This is one working example of the TOC analyzer and its
useful application  for controlling efficiency in municipal
waste treatment processing plants. Many other applications
for the TOC analyzer are employed as it is widely used by
American industry, which has traditionally accounted for
the largest sector of the TOC analyzer production output.
Whether the TOC analyzer  be  used  as  a laboratory or
continuous  in-line device,  the  results and  application
potentials remain  the same;  only the means of sampling
changes.

Summary

   In conclusion, I have discussed three treatment modifica-
tions that  have the advantages of improving  treatment
efficiency and  reducing costs.
   The closed-cycle mill, which can be a modification of
existing kraft pulp plants, totally eliminates contaminated
effluents while saving enough through operating expenses to
recover its initial capital expenditures in a two year period.
After the two years  of  operation, the closed-cycle mill
continues to generate these  savings as revenue - a prospect
that  external waste treatment facilities cannot offer.
   The high-solids  filter has application for both municipal
and industrial sludge processing. This new development is a
modification in sludge processing that promises to reduce
energy consumption and increase energy recovery in sludge
thermal systems.
   The TOC  analyzer also  has applications  for  both
industrial and municipal treatment processes. Although no
examples of industrial uses were given, the product is most
widely purchased  for  industrial  applications. The  TOC
analyzer has the advantage of being a reliable and quick
measurement tool  that has  found application in improving
waste treatment efficiency  through  a  network of feedfor-
ward and  feedback control  strategies in addition  to its
general application as  a monitoring device.


Bibliography

 1. Papermakers  Face More Pollution  Woes, Chemical
   Week, p  35, May 5, 1976.
2. TAPP1 Medalist, Tappi, 58:12, p 3, December 1975.
3. Stevens, F., First  Pollution Free Bleached Kraft Mill
   Gets Green Light, Pulp and Paper Canada, 76:10,  p 27,
   October  1975.
4. Rapping With  Rapson,  Pulp  and Paper, October  1973,
5. Emmerson, D. W.,  The  Long Hard Road  To The
   Effluent-Free Mill,  Chemistry In Canada, p  11,  April
   1976.
6. Cornell,  C.F.,  Salt  Recovery Process  Allows Reuse of
  Pulp-Bleaching Effluent,  Chemical Engineering, p  136,
  November 10, 1975.
7. Rowlandson, G., Economic Advantages of Closed-Cycle
  Mill, Erco-Envirotech Study, December 15, 1975.
8. "Zero Pollution  From A  Paper Pulp Process," Business
  Week,  p 48, December 22,  1975.
9. Development Document for Interim Final and Proposed
  Effluent  Limitations  Guidelines  and  Proposed  New
  Source Performance Standards for the Bleached Kraft,
  Groundwood, Sulfite, Soda, Deink and Non-Integrated
  Paper  Mills,  (Vol. I) Segment  of the Pulp,  Paper and
  Paperboard  Point  Source  Category,  United  States
  Environmental Protection Agency, p 31, January 1976
  (EPA 440/ 1-76/047-a).
10.  Economic  Analysis of Proposed and  Interim Final
  Effluent Guidelines for the Bleached Kraft, Groundwood,
  Sulfite, Soda,  Deinked and  Non-Integrated  Paper
  Sectors of the Pulp and  Paper Industry, United States
  Environmental Protection Agency, p 12,  January  1976,
  (EPA-230/2-76-045).
11.  State of the Art Review on Sludge Incineration Practice,
  U.S. Department of Interior  17070 Div. 04/70.
12.  Stensel, H. D., Shell, G. L., Two Methods of Biological
  Treatment Design, JWPCF \(s(2), p 271, February 1974.
13.   Joyce,  R.  J.,  Ortman, C., and  Zickefoose,  C.,
  Optimization of An Activated Sludge Plant Using TOC,
  Dissolved Oxygen, Respiration  Rate and Sludge Settling
  Volume Data, Presentation before WWEMA Industrial
  Water and   Pollution  Conference, Detroit,  Michigan,
  April 1, 1974.
                     WHITE LIQUOR
                       DIGESTER
                       COOKING
                     BROWN STOCK
                       HASHING
                      WOOD
                      BROWN PULP,
                     BLACK LIQUOR
                      EVAPORATOR
PURGE  ATMOSPHERE)
    FURNACE
 PURGE   .
  DREGS «-
  GRITS
Figure 1
LIQUOR PREPARATIOt!
                                                        45

-------
  Purge.
  (Dfffli)
  (Gths)
 Purgt
CO.& H,0
M,0
N_
\_



L'rjuor
Preparation


*»-

A
Bl«c» Liquor



r
Condcnijlt
While Liqu



Cooking *

1 " Stripp
/
H,0


Pulping
Chemical J
NaCH
Nt.S
.'

Bit ching
Ch -nical t
M*nu'aetur«
CI6,
Cl, y
NaOH ^
I Bl»ching "*" H,0 *
                                                  -». Bleached  .
                                                      Pulp   '
 Figure 2


EVAPORATOR"
CBYUM.LUEI
>ITI ,_] STAGE 1
MOT U.AIII FUR
lAORjAjSjNAjCOj
(UCl JA2SO(,





PHA
IE
SEPARATION


UNREG!
CHEMIC


A

i
Figure 3


BLEACH PLANT





SHITE





EVAPOHATOR:-
CRVSTALLIIEM
STAOE 1!
PHASE
SEPARATION
fRATED
LtdUQR
NE RATED PuiriK
KLS TO BLACK LiauoR

















6o.c»
®\
NAtL
PURIFICATION
PHASE
SEPARATION




RECYCLE I
2 * RECOVERED
SODIUM
'RATED
 ouoa
iESIEH
                                                                     Estimated Annual Operating Cost Savings Closed-Cycle Mill Salt
                                                                                            Recovery Process
                                                                                    (Calculated l<> Nearest Tliousand)
          1. Heat  Savings
            A. Decreased  Steam Consumption
            B. Additional Steam Production
               from Reclaimed Organics
          2. Fiber Savings
          3. Yield Increase
          4. Chemical Savings
          5. Water Savings
          6. Savings in Effluent Treatment Cost
Dollars
$ 839,000
$ 271,000
$ 776,000
$ 636,000
$1,189,000
$ 68,000
$1,584,000
Rubles
634,284
204.876
586,656
480,816
898,884
51,408
1,197,504
                                                                                                           $5,363,000    4,054,428
            Basis: 900 TPA (409,0001 day) Coniferous Pulp - KAPPA No. 32
            Bleached Pulp Brightness - 90 (G.'E.)
                                                                                               Figure 5
          Capital and Operating Costs

          Mill Capacity

          White Liquor Use
          Active Alkali
                                                                     Sodium Chloride Recovered

                                                                     Capital  Cost

                                                                     Utilities
                                                                     Steam
                                                                     Power
                                                                     Water
                                                                     Raw Materials:
700 A.D.  tons per day
(636,000 kg per day)
130 ft' per ton pulp
793 Ibs Na20 per ton pulp
(324 kg per 1,000 kg pulp)
120 to 200 Ibs NaCl per ton pulp
(54.5  to 90.9 1,000 kg)
$8,000,000
(6,048,000 Rubles)

96,000 Ibs per hour (43,636 kg/ per hour)
875 H.P.
6,000 G.P.M (surface condenser)
None
                                                                                                Figure 6
 PC. . process
 SC . s'eam co^dcnsate
 HE... fient enchangc

 Figure 4
                                                               46

-------
                      DESIGN CONDITIONS
                      GAS EXIT TEMP.-
                      EXCESS AIR	
                         FBF

                        150(fF
                        202
                                                      HHF*
                                                      800* F
                        FLUIDIZED BED
                           FURNACE
                         WITHOUT HEAT
                           RECOVERY
                              FBF
           FLUIDIZED BED
              FURNACE
             WITH HEAT
              RECOVERY AND
                PREHEAT AIR TO
                   1000' F
                X TOTAL SOLIDS  IN  SLUDGE
          @ 75% VOL AND 9500 BTU/LB.  VOLATILE

* Multiple Hearth Furnace  - 22'  dia.;  6 hearths
  Source:  (11) and Dnvirotecli data

 Effect of moisture content on the  cost of sludge combustion
          systems with and without heat  recovery

 Figure 7


                    Performance summary
                    Hatfield, Pennsylvania
 Filter
 Type
 Drum
 Hi-solids
   Production
(Kg DS/hr-sq m)
      6.8
      9.1
     Filter Cake
DS-% Kg  H20/Kg DS
     20.2  3.95
     32.8  2.05
                          Figure 8
 Incineration Fuel Comparison
 Dry sludge solids
 Per year; metric tons
 Cake; % ds
 Gross Heat required;
 Billions BTU per year
 Fuel  cost   2.0 U.S.
 Dollars per million BTU:
 U.S.  dollars per year
 Rubles per year
Vacuum
niter
5000
20
108
216,000
Hi-solids
niter
5000
27
73.0
146,000
                 163,296       110,396
        32% FUEL SAVINGS

      Figure 9
                            Sewage treatment plant locations with sludge energy recovery
                            systems
                            (United Stales)

                             1. Central Contra Costa Sanitation District, California
                             2. Jacksonville, Florida
                             3. Granite City, Illinois
                             4, Western Branch Facility, Prince Georges County, Maryland
                             5. Atlantic County, New Jersey
                             6. Trinity  River Authority, Texas
                             7. Hatfield. Pennsylvania
                             8. Chesapeake-Elizabeth-Hampton  Roads  Sanitation  District
                               Virginia,
                             9. Hopewell, Virginia
                            10. Green Bay,  Wisconsin
                                                                      Figure 10
                                             Hi-solids filter capability
Sludge
type
Raw Primary
Waste activated
Raw primary plus
waste activated
(50:50 by weight)
Raw primary plus
humus (50:50 by
weight)
Heat treated raw
primary plus waste
activated
PCT (lime)
Production
(Kg DS/hr-sq m)
25-50
7-10
10-15


15-20

15-25


10-20
Filter cake
DS-% KG H20/
KgDS
30-40 1.5-2.3
18-20 4.0-4.6
24-28 2.6-3.2


25-27 2.7-3.0

45-55 0.82-1.2


30-35 1.9-2.3
                                                                      Figure 11
TO^IAM ^Ml ^HL TQ^IIC
1 1 1 1
I i i i
I

imiuutr


NIHMV
IfTTllM



ID
|
1 .




. hut






|
1 .



SECONDAftV
SETTLIM

(uii T
*ll
	 TOCM,
|

SrrflOH*Bt *
FINAL
EFFLUENT



                                                       WAS  =  waste sludge flow
                                                       RAS  =  return sludge flow
                                                   TOC RAW  =  TOC of raw influent
                                                    TOC PRI  =  TOC of primary effluent
                                                    TOC ML  =  TOC of mixed liquor leaving aerator
                                                    TOC SEC  =  TOC of secondary of final effluent
                                                   TOC RAS  =  TOC of return activated sludge

                                                                       Figure 12
                                                             47

-------
    100-

 —  80-
 o
 S  60-
    40
    20-
      o
 •a
                  Hillsboro plant performance
                                                               Estimated annual operating cost savings closed-cycle mill salt
                                                               recovery process
                                                               (Calculated to  Nearest Thousand)
 I. Heat Savings
    A. Decreased Steam Consumption
    B. Additional Steam Production from
       Reclaimed Organics
 2. Fiber Savings
 3. Yield Increase
 4. Chemical Savings
 5. Water Savings

 6. Savings  in Effluent Treatment Cost
                                                                                                               S  839,000
                  1972
                                     1973
                                                                                                                $  271,000
                                                                                                                $  776,000
                                                                                                                $  636,000
                                                                                                                $1,189,000
                                                                                                                $   68,000
                                                                                                                SI.584,000
                                                                                                                $5,363,000

    500
   400
 I 300
O 200
|  100-
O
               final effluent
                                          new operating
                                          strategy
Figure 13

— 250
£ 200
 fea«

 § 150-
 n
 s 1CO
2  50
§
E   0-
                  1972
                        primary
                        effluent
                 ."•XA
                                     1973
                                             »  '
               1972
                                    1973
    150

 f  125
 a
 a.
 w  100

 i1   75

 >   50

 |  25

     0-

Figure  14
                                        new  operating
                                        strategy
                                           i  i  primary
                                      »' */'  ! effluent
                                             t
                                              i
                                              i
                                              i
                                              i
                                              i
                                      final effluent
              1972
                                   1973
C
6.5%
0
0
0
0
6.5%(130#)
E
0
4.50%
0.20%
0.50%
0.05%
5.25% (105#)
D
0
0
1.0%
0
0.5%
1.5%(30#)
BASIS: 900 TPD Coniferous Pulp - KAPPA No. 32
  Bleached Pulp Brightness - 90 (G.E.)

CONIFEROUS PULP—900 T/D - 345 D/YR
                     —310,500 T/YR

(1) Bleacher} Sequences C-E 1-D i-E z-D 1
                                                                    Stage
                                                                      1
                                                                      2
                                                                      3
                                                                      4
                                                                      5
Chemical Balance:
  1# Chlorine Requires 1.I3# NaOH
  1# Chlorine Dioxide requires 0.60# of NaOH
  .'.Checking Cl- and Na+

Chloride (Caustic)
1st Stage C = 6.5% =  130#/T =  130 x 1.13 = 146.9
3rd Stage Di  = 1.0% = 20#/T = 20 x 0.6 =  12.0
5th Stage D 2 = 0.5% =  10#/T = 10 x 0.6 = 6.0
Total caustic required (for "balance") = 164.9#/T

NOTE: All units are  U.S., i.e. tons are short tons (2000 Ibs).

Sodium
2nd Stage (E i) = 4.50% = 90.0# (1st extraction)
3rd Stage = 0.20% = 4.0# (buffer-pH control)
4th Stage (E 2) = 0.50%  - 10.0# (2nd extraction)
5th Stage = 0.05% = 1.0# (pH control)
Caustic added in bleach plant - 105#
.'.additional caustic to  "balance": 164.9 -  105  = 59.9#/T.  This
amount must be added to the mixed nitrate for link-up of Cl- and
Na+ (as NaCl) and need for pH adjustment.
                                                               Sodium Chloride Load:
                                                                      Stage
                                                                        1
                                                                        3
                                                                        5
                                                                                      Chlorine
                                                                                        130.0
                                                                                         0
                                                                                         0
                                                                                        130.0
                                          Chlorine
                                          Dioxide
                                             0
                                            10.5
                                            5.2
                                            15.7
                 Appendix  1(7)
                                                               Total chloride = 145.7
                                                               .'.Total sodium chloride load (as NaCl)
                                                               = 145.7 x 58.5 = 240#/T
                                                                        35.5
                                                          48

-------
 Total dioxide needed - 1.5 x 900 = 13.5 T/D
                       100

 (2) Bleachery Sequence D/C-Ei-Di-Ei-D2
 (Based on 70% substitution with chlorine dioxide in the first stage)
 —30% as C12 = 1.95% - 39.0#/T
    Chloride Load - 39.0#/T
 —70% of total Cl2 demand as dioxide
    C102 as CI2 - 0.7 x 6.5 - 4.55%
    as C102 = 4.55= 1.73% = 34.6#/T
             2.63

    Chloride load  = 34.6 x 35.5 = 17.9#/T
                         67.5

    Total  chloride (C1-)  load = 39.0 +  17.9  +  105  (Di)
    + 5.2 (D2) = 72.6
    Sodium chloride (NaCl) load
  = 72.6 x 58.5 - I20#/T
          35.5

 Balancing Cl- and Na + (actual NaOH = 81#/T)
 Caustic Requirement:
   Stage

     1
     2
     3
     4
     5
     Chlorine
    (as NaOH)

39.0 x 1.13 = 44.10      —
                        44.10
Dioxide
Caustic
—
64
6
10
3
83#
(as NaOH)
34.6

20

10

x 0.6

xO.6

xO.6

= 20.76
	
= 12.00
	
= 6.00
38.76
 Caustic requirement = 44.10 + 38.76 = 82.86#/T
 .'.Cl- and Na+ are balanced (NaCl)
 Total dioxide needed
  = [1.73% + 1.0% + 0.5%] x 900
           100
   +3.23_x 900 = 29.07 T/D
    100
 (3) Basic Data
    (a) Costs
       Chlorine
       Caustic Soda
       Chlorine Dioxide
       Wood
       Unbleached Fiber
       Fiber in process
       Pulp "semibleached"
       Bleached Pulp
       Steam
       Water
       Effluent and
       Emmissions
                     6.5t/lb.
                     7.0c/lb.
                    24.0c/lb (R3)
                   $40/cord (2.25 cords/T)
                  $ ISO/Ton
                  $195/Ton
                  $250/Ton
                  $360/Ton
                    S2.25/M Ibs. (Total Cost)
                     2c/M Gals (Incl power,
                    labor & treatment)
                  $7/Ton (OECD, Ekono)
                    (For primary & secondary)
       tions  of  bleach  solutions,  etc.,  is   approximately
       130,000#/Hr. The steam required to concentrate the mill
       white liquor in the SRP in order to remove the salt load is
       approximately 85,000#/HR (quadruple effect).
       .'. Differential 130,000 - 85,000 = 45,000#/Hr
       Savings = 45,000 x 2.25 x 24  x 345 = $839,000/yr.
                         1,000

    (B)  Steam Production (Higher Organlcs S4T/D)
         Bleachery shrinkage 6% overall—recovery boiler (steam)
         efficiency 65% [decreased inorganics—sodium carbonate,
         sodium sulfate (as well as make-up salt cake) considering
         salt input] recovered organic solids heating value 5,000 +
         B.T.U./lb.

 Savings = 0.06 x 310.500 x 2,000 x 5,000  x 2.25 x .65
                 1,000,000
 = $271,000/yr.

    (C)  Fiber Loss Decreased ("average"  pulp price $250/Ton as
         fiber not completely processed—bleached nor dried)
         Elimination of fiber loss from dryer, bleachery, screening
        and washing departments means an "average" fiber gain of
         1.00 x 900 = 9.0  T/D. This pick-up  increases pulp
         100   .
        production—decreases  chemical  usage—or mill may
        choose depending on boiler  capacity, etc., to  decrease
        amount of wood cooked (lower overall and organic load
        to the recovery boiler).
Savings = 9.0 x 250  x 345 = $776,000/yr ("Increase  Income")

    (D) Yield
        Due to the high substitution (70%) with chlorine dioxide
        in the first stage (since it will be operated "HOT") there is
        a yield improvement of at least one (1) percentage point
        when compared to a hot chlorination  sequence. This
        enhancement due mainly to  the protection of the hemi-
        celluloses will coincidentally  decrease other associated
        processing charges so that an overall cost  advantage of at
        least S2.05/T may be realized.

Savings = 2.05 x 310,500 = $636,000/yr.

    (E)  Bleaching Costs
        **  (i)  For  the sequence C-Ei-Di-Ez-D2  the chemical
        consumptions are:
              Chlorine   =
          Caustic Soda   =
      Chlorine Dioxide   =
130#/Tat6.5c/lb = $ 8.45
163#/Tat7.0c/lb = $11.55
 30#/Tat 24t/lb = $ 7.20
   Total Chemical: $27.20
    (b) Operating days per year                           345
    (c) Bleachery Chemical shrinkage                      6%
       (Minimum of one (1) percentage point yield gain due to high
       substitution with C1O2 for Cl2 in the 1st stage.)
    (d) Bleachery fiber loss l%(average-withconventional"C"and
    "El" filtrates sewered)
(4)  Estimated Savings ** Per year (D/C-Ei-Di-Ei-DJ)
    (A) Steam Consumption
       The decreased amount of steam due to: lower water volume
       used, countercurrent reuse of filtrates, modified concentra-
                                                          (F)
       (ii) For  the  sequence D/C-Ei-Dt-E2-D2  the  chemical
       consumptions are:

                 Chlorine =  39ft/T at 6.5c/lb    =
            Caustic Soda =  83#/T at 7.0/lb      =
         Chlorine Dioxide =  62.6#/T at 24c/lb   =
                             Total Chemicals   =

              Differential =   27.20 - 23.37 =   S3.83/T
                 Savings =  310,500 x 3.83 = $l,189,000/yr,

       Effluent and Emissions - Treatment
       (a)   Based on independent cost data, the treatment cost
            (primary and secondary only)  amounts to approxi-
            mately  $7/Ton  (Including power, oil, gas, labor,
            steam, air, chemicals,  lime, phosphate, ammonia.
                                                             49

-------
           sulfuric, special reagents).
       (b)  Selective reuse is made of separated and steam - (high
           percentage)  stripped  contaminated   condensates
           within the mill. Cost incurred amounts to $ 1.90/ Ton.
           Annual cost = 1.90 x 310,500 = $590,000/yr
       (c)  Annual savings is the differential for these treatments;
           namely, 310,500 ($7- $1.90) = $1,584,000

   (G) Water Consumption
       "Average" water quantity - 35,000 gpt (total)
       "New" water quantity = 4,000 gpt (bleachery countercur-
                            rent  use, etc.,)
                          = 20,000 gpt * (surface condensers,
                            utilities, cooling)
       'Thermally  enriched water  which can be discharged
       directly through the sewers or to the  river or lake without
       effluent treatment.  It may be reused in some locations
       (northern climates) or for associated mills.  At millsites
       where temperature levels are of concern, cooling towers
       (as are now in use) are installed.
       Overall  decrease  in   water  requirements = 35,000  -
       24,000= 11,000 gpt
       Savings = 11,000 x 2_x_310,500 =  $68,000
                1,000   100
       Total Annual Savings = $5,363,000/yr.
       **(i) The estimated amounts  of  the major  savings
       (accounting for the "extra" steam consumed for  the
       evaporation-crystallization phases of the SRP flowsheet)
       are tabulated herein based on various  cost assumptions
       (listed for reference) which are considered quite conserva-
       tive as compared to actual forecast or even present values.
       (ii)  If  the  conventional  sequence C-E1-D1-E2-D2 is
       practiced and there is no reclamation of bleachery filtrate
       back through the unbleached pulp  washing, there is no
       need "within" the mill to add extra balancing caustic (it
       would then dictate, however, installation and  operation of
       external effluent treatment and use  of additional lime to
       adjust effluent  pH). Then the bleachery  chemical cost
       would be $23.00/Ton.
NOTE: You may wish to consider partial recovery of effluent in
some instances with evaporation of commensurate volume of white
liquor to control the salt load.

       (iii) No credit has been taken for the salt (NaCl) removed
       and purified in the SRP flowsheet. Average salt (basic
       price) cost  is  approximately 0.64t/lb.  Said  sodium
       chloride  may be  reused  for  generation of  bleachery
       agents—for roads or otherwise disposed of. If consumed,
       the savings = 120 x 310,500 x 0.6 = $224,000
                                 100
       (iv) No credit has been taken for the ("low level") large heat
       quantity  available  from the thermally enriched water
       which may be of considerable economic use by associated
       facilities (surface condenser waters,  etc.).

The term SRP as used in this comparison is  a trademark of Erco
Envirotech Ltd.
Biological  Waste  Water

Treatment  in  the  Presence of

Steroid  Compounds

S.V.  Yakplev
T.A. Karjukhina

  The principle  possibility of stimulating the process of
biological  oxidation  in  aerobic conditions by means of
addition of steroid compounds to the water to be treated
was investigated.
  As a basis for carrying out investigations, a known  fact
was taken which established experimentally  that steroid
compounds added to the culture medium have various
effects on pure cultures of microorganisms.
  Effects of three major types have been defined: steroids
are  growth  factors;  they  would  stimulate or  inhibit
metabolic  processes   in  the  cell;  and  would  protect
microorganisms against the action of toxic substances.
  It is supposed, that some of the steroids would be toxic to
the cell, and therefore, the transformation of steroids inside
the cell, leading to formation of non-toxic substances,  is a
sort of protection of the microorganism. The action of four
steroid hormonal preparations, produced  on commercial
scale, was  investigated.
  These are: methyltestosterone (I), testosteronepropionate
(II), progesterone (III), pregnine (IV).
  The first part of the investigations has been carried  out
using synthetic waste  water  (SWW), which included such
components  as  peptone,  buffer   ammonium  salts   and
dipotassium hydrogen phosphate (KaHPCM).
  The first part of the investigations consists of three sets of
experiments:
   1. Oxidation in Warburg apparatus;
  2. SWW treatment in mixing aeration tank models;
  3. Aerobic mineralization of activated sludge (in models).
  The conditions for carrying out  the experiments and the
results, which have  been obtained for the sets of experi-
ments, are briefly described below.

1.  Oxidation in  Warburg  Apparatus.

Conditions of experiments:
—temperature of mixture - 25° C,
—concentration of activated sludge, adapted to SWW  and
   to the appropriate steroid, is about 1  g/1,
—incubation time - 5 hours, Teachings taken every half an
   hour.
  The  investigated  substances are insoluble  in  water,
therefore they were added to  SWW in the form of alcoholic
solution. The same  amount of alcohol, but  without  any
steroid, was added to the control flask.
  The results of the first sets, averaged from many tests are
shown in Table I.
                                                        50

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        Table I. Oxygen demand for Sh incubation % tng/1

     Steroid              Steroid Concentration

1
11
III
IV
0
100
100
100
100
1
141
161
127
144
2
115
142
113
139
5
105
136
107
95
10
113
112
104
46
15
89
116
103
60
20
92
116
100
63
25
_
100
104
66
30
44
103
99
67
Note: Oxygen demand in the control flasks, taken as 100%, for
experiments with substance I was 137 mg/1 substance 11-249 mg/1,
substance 111 • 176 mg/l and substance IV - 158 mg/l.

   Conclusions:
   a)   Addition of steroids has a marked effect on the
        activated sludge oxygen demand in the process of
        peptone oxidation.
   b)   The action of the four compounds is of similar
        nature,  while the degree  of influence is different.
        Maximum   increase   in   oxygen  demand  was
        observed at  steroid   concentration of  1  mg/l.
        Further increase in steroid concentration resulted
        in  decrease  of  oxygen  demand. Within  the
        concentrations investigated two substances, I and
        IV, had an inhibitory effect, this being expected for
        substances  II and  III at concentrations above 20
        mg/l.
   c)   Results of this set of experiments have confirmed,
        that it would be advisable to carry out investiga-
        tions in aeration  tank models with continuous
        cultivating of microorganisms.

  2.  S\VW Treatment in Mixing  Aeration
     Tank Models.

  Experiment conditions: capacity of aeration tank model -
10 1,  settling tank - from 1.5 1 to 2.0 1. Time of each cycle -
not less than 20 days (to obtain stable results) and not more,
than 43 days. 5  cycles  in total have  been studied  with
aeration duration 12, 9, 6, 3 and 2 hours.
  Table 2 shows basic results, averaged from 5  to 10 tests.
Discussion of the results obtained: The fact that BODs of
SWW with the steroid added is higher, than BODs of the
control sample is of interest. Increase in BODs for the four
preparations is different. The average increase in BODs with
the addition  of substance  I is 8%,  substance  II  - 15%,
substance III - 40% and substance IV - 68%. In three of the
five cycles with aeration duration of 12,9 and 6 hours tertiary
treatment took place in all models.  BODs removal was
actually the same for all aeration tanks, variations in effluent
BODs value being relatively small. Differences in effluent
COD were  observed,  the  COD  of  the  water from  the
experimental models being somewhat lower, than that from
the control models.
  In 3  and  2 h  cycles the  treatment  was  incomplete.
According to average results effluent BODs was more, than
25  mg/l, and  for individual samples up to 150 mg/l.
Supposedly,  there was no time for  pregnine (IV) to be
metabolized during such a  short period  of treatment, as
effluent BODs was higher than COD value.
  Because of high sludge loadings, deficiency of dissolved
oxygen was felt in some cycles that would partly limit the
oxydation rates. The sludge of the first  three cycles was
swelled and rich in various Protozoa. In two last cycles the
sludge index  was very high. The sludge biocenasis of these
cycles was noticeably poorer than in the first three sets.
  Estimates of the amount of sludge growth have shown that
under conditions of tertiary water treatment (in 12 and 9 h
cycles) the growth in experimental aeration tanks was higher
than in the control  one, in 6 h cycle-approximately the same,
and in 3  and 2 cycles lower than in the control unit.
  As a result of comparison of relative effluent BODs values
and oxidation rates, it is possible to state that the presence of
steroids makes the treatment of water more rapid and more
effective. The latter is fixed by lower values of effluent COD
in the experimental models (in the first three cycles); this
means that substances, which are difficult to oxidize, have
been implicated in the treatment processes.

Conclusions
a) The stimulating action of the steroids  on the oxidation
Table 2. Performance of aeration link model with the steroid substance added to waste water it concentration of 1 mg/l
Aeration duration (h)
12 9
Nos Parameter Control



2

3

4

5
6

7



Influent BODs
(mg/l)
Effluent BODs
(mg/l)
Effluent COD
(mg/l)
Sludge dosage
(g/D
02
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   processes have been observed in activated sludge during
   synthetic waste water treatment, prepared on the basis of
   peptone at steroid concentration of the treated water 1
   mg/1.
b) Biological treatment of water will be more rapid and more
   effective in the presence of steroids. Substances, almost
   not available for activated sludge microorganisms under
   normal conditions, will be implicated  in the oxidation
   processes.
c) The effect of the four substances studied was not specific;
   that allowed to considerable extend the sphere of search
   for most effective stimulators among the lots of steroid
   compounds.

3.  Aerobic Mineralization of Activated
    Sludge.

   Experiment  conditions: capacity  of mineralizer -51.
Steroid concentration in each model 0.2  mg/1. Experimet
duration - 20 to 26 days. Activated sludge, adapted to the
appropriate steroid (as  from aeration tank models), was
investigated, as well unadapted sludge, which was taken from
the operating  treatment plants of  the city of Moscow.
Temperature is 20° C.
   The  degree  of activated  sludge mineralization  was
estimated only as ash  content.

Conclusions
a) Addition of steroids  at concentration  of 0.2 mg/1 will
   stimulate processes of aerobic mineralization of sludge.
b) The effect of steroids will show in two ways and will result
   in reaching the required degree of mineralization for a
   shorter period of time or will ensure a higher degree of
   mineralization for the same time of treatment.
c) The effect of the steroids is not specific. Only the degree of
   influence of the steroid will be different.
   The second part of the investigations has been carried out
on municipal sewage, fed to the operating treatment plant of
the city of Moscow. The second part consists of some sets of
experiments for BODs measurement by the dilution method.
The following problems have been investigated:
   1)  Effect of steroids on BODs value of the clarified water,
supplied to the biological treatment plant;
   2)  Effect of steroids on BODs value of the effluent water
from the aeration  tanks of the  plant.
   3)  Action of steroids,  when an inhibitor of the biological
treatment process, such as cuprous sulphate, was added to
the waste water.
   Some of the results obtained are described below.

1) Effect of  steroids  on BODs  of clarified
     water

   Experiment conditions: steroid in the form of alcoholic
solution was added to the diluting  water, used for BOD
measurement by the dilution method. The same quantity of
the alcoholic solution was added to the control bottle, but
without any steroid.
   Results  obtained and conclusions:  some  hundred of
individual  measurements have  been  carried out, both on
single waste Water samples  and daily average ones. The
addition of steroid varied within 0.1 mg/1 and 2.0 mg/1.
Substances I, III and IV were investigated.
  The addition of alcohol resulted in sharp rise of BODs
value. During the investigations BODs of the clarified water
varied within 70 mg/1 and 140 mg/1.
  According to the quantity of alcohol added, BODs of the
control sample increased up to 202 mg/1 to 1780 mg/1. This
being so, it was found possible to show the effect of steroids
only after a great number of experiments. Table 3 shows, as
an example, the results obtained with progesterone (111).

Table 3
Concentration
of
substance
III(mg/l)
1
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.1
1.3
1.5
1.7
1.9
BODs

initial

2
100
97
104
95
137
139
93
71
110
96
122
86
88
92
of waste water

with alcohol

3
202
308
429
528
712
745
997
872
1265
1405
1540
1170
1460
1780
(mg/l)

with alcohol
and HI
4
208
320
437
561
671
799
948
992
1225
1360
1350
1118
1288
1620
   Similar results have been obtained with other substances.
 Data in Table 3 show, that at progesterone concentrations
 of 0.1 mg/1 to 0.8 mg/1, a small increase in oxygen demand
 will occur, while at concentrations above 0.8 mg/1 there will
 be a  decrease in oxygen  demand, as compared with the
 control. Since in reality the addition of steroids in the form
 of alcoholic solutions is not advisable, subsequent experi-
 ments were carried out with the addition of investigated
 substances in  the form of dry powders.
   This  version  of the experiment gave a  pronounced
 increase  in BODs, and for progesterone, for example, the
 value was quite impressive - from 69% to 279% (see Table
 7).

 Conclusions
 a) Addition of steroids will have a marked effect on BODs
    value  of  the  waste  water,  measured by  the dilution
    method
 b) The action of steroids will depend on the concentration
    of steroids.
 c) Direct addition of the steroids in the form of dry powder
    will result in  sharp stimulating of biological  oxidation
    processes,  when the  dilution method is used for BOD
    measurement.

 2) Effect of steroids on BOD s value of
    effluent  water from the aeration tanks of
    the plant

   Experiment conditions: steroids were added in the form
 of alcoholic solutions and dry powders.
                                                      52

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  The results, averaged  from many tests, are shown in
Tables 4, 5 and 6.

Table 4
                                                            Table 7
Concentration
of substance
HI
(mg/l)
0.2
0.3
0.5
0.7
Effluent
initial with
9.6
8.1
6.5
6.5
BODs(mg/l)
alcohol with alcohol
and III
202 181
241 301
509 520
635 621
Table 5
Concentration of
substance
(mg/l)
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Effluent BODs(mg/l)
initial
10.5
12.0
10.9
9.9
10.9
10.9
11.4
13.8
with powder
12.4
13.0
12.0
13.5
11.5
13.6
13.4
15.6
Table 6
Concentration of
substance
HI (mg/l)
0.5 - 2.0
Effluent
initial
3.5 - 16.4")
9x1)
BODs(mg/l)
with powder III
20.0-78.1*)
57**;
Note:  x) Variation limits
      xx) Average BODs value

Conclusions
a) Steroids will have a much more pronounced effect when
   added in the form of powder.
b) The degree  of  influence  of various steroids will  be
   noticeably different.

3)  Effect of steroids with addition of
     inhibitor  to waste  water

  Experiment conditions: Progesterone (III) was added to
the clarified water  in the form of  dry  powder. Cuprous
sulphate and cuprous sulfate with progesterone were added
to the parallel samples.
  The results of the experiment are shown in Table 7.
BODs of clarified waste water
(mg/1)
with cuprous
Initial with powder sulfate-
108 208
110 186
76 288
62 215
76 208
65
75
34
87
53

with cuprous
sulfate and II
105
118
206
184
132
Conclusions
a) Steroids would be used as measure for protection of
   activated sludge microorganisms against the action of
   toxic substances.
  Some of the results, obtained for the effect of steroids on
waste water  treatment  processes, briefly described  here,
allow to make the following general conclusions:
  1. The group  of steroid hormones is biologically active
and  will stimulate (or  inhibit) treatment  processes with
complex activated sludge biocenosis.
  2. Steroid  substances will  stimulate processes at low
concentrations (up to 1 mg/l) and will inhibit them at high
concentrations. Stimulation will manifest itself in implicat-
ing in processes organic substances, both exogenous and
endogenous,  which  are difficult  to  oxidize  and  also in
accelerating the  processes.
  3. The effect  of the steroid hormones studied was not
specific, while the degree of influence on the process was
different, which will allow to extend the sphere of search for
the most available, inexpensive and effective preparations.
  4, In the processes of biological treatment of waste water
in aeration tanks, many organic substances remain in the
effluent water which would be oxidized if steroid stimulators
were added to the water.
  5. Investigations of technological aspects  of the effect of
steroid stimulators should be supplemented  with biochemi-
cal  investigations to  elucidate the mechanism of action of
the substances.
                                                        S3

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A  Comparison  of

Conventional Activated

Sludge  Process  and  Pure

Oxygen  Activated  Sludge

Process  for  a 75-MGD

Secondary Treatment Facility

Fred A. Harper,
General Manager
Orange  County Sanitation Districts
California

  This paper will discuss the process by which a pure oxygen
system was selected over a conventional air system for a 75
mgd facility to adequately and economically produce the
required  effluent to meet State and  Federal discharge
requirements.  Included in this discussion is a description of
a pure oxygen wastewater treatment system for open tanks.
  The Orange County  Sanitation Districts provide for the
collection,treatment and disposal of domestic and industrial
liquid wastes  for a service area of  320 square  miles in
Southern  California, on the  West Coast  of the United
States. The area has a population of 1 !/2 million people in 23
communities,  including the internationally known tourist
attraction, Disneyland.
  The agency operates two primary treatment  facilities
which are presently being upgraded to comply with State
and  Federal  secondary treatment  requirements. At Plant
No. 1, which is a 50 million gallons per day (mgd) facility,
an air activated sludge process plant is being constructed
and is scheduled to  be operational in January, 1977. Plant
No. 2 is essentially a primary treatment facility, having a
present rated  capacity of 130 mgd  average flow with  a
hydraulic maximum of 230 mgd.
  Existing treatment comprises screening, pumping,  grit
removal,  primary  sedimentation, and  chlorination when
necessary. The effluent  is pumped into the ocean five miles
offshore through an outfall diffusion system some 6000 feet
long.  Sludge collected in the primary sedimentation basins
is anaerobically digested and then dewatered by centrifuga-
tion. The  dewatered sludge is sold to a soil supplement
manufacturer.
  A  1974 report   investigated   alternative  wastewater
treatment  and disposal projects for meeting the State  and
Federal  secondary  treatment  water quality  goals  and
included  the  analysis  for 16 candidate systems and an
implementation  schedule for improved treatment.  This
program  called  for staged additions totaling  175 mgd of
secondary treatment at Plant No. 2. The first stage is a 75
mgd addition.
  Four alternative systems were selected for final evaluation
from  the  16 candidate systems:
  A.  Air  activated  sludge
  B.  Pure oxygen activated sludge
  C.  Roughing filter and activated sludge
  D.  Roughing filter and pure oxygen activated sludge
  The following preliminary design  criteria and physical
characteristics for the  four alternatives for the  75  mgd
facility were developed for the purpose of determining the
necessary  land  requirements,  energy  demand,  sludge
production and over-all costs.
  Primary effluent  BODs is assumed to be 225  mg/1,
suspended solids 142 mg/1 and grease 35 mg/1.
  Aeration and  oxidation facilities are sized based on a
sustained 10-hour daily flow of 1.2 times the average flow. A
sustained (peak month) primary effluent BODs of 1.25 times
the  annual average BODs and a  sustained daily primary
effluent BODs of 1.20 times the daily average BOD5are also
used as  a basis for biological facility design. The over-all
removal is assumed to meet the Federal effluent standards as
follows:

  BOD = 30 mg/1 -Monthly Average
    SS = 30 mg/1 -Monthly Average

  The  wastewater flows  entering  the existing treatment
facilities have  shown peaks of nearly two times the average
flow. These peaks lasted 8-10 hours  and occurred when
influent flow was actually restricted because  of surcharged
influent sewer lines. These conditions necessitate a peak
design flow two  times the average  flow.
  The  following  is  a  general comparison  of normal
operating and design parameters for pure oxygen and air
activated sludge processes:

Normal operating and design parameters based
on typical municipal sewage
 Conventional Air
 Activated Sludge         Parameter         Pure Oxygen
       3-8      Oxygenation Detention Time,
               Mrs.                         1.0-2.5
    2500-4000    Mixed Liquor Suspended Solids
               (MLSS), MG/L              3000-7000
    2000-3200    Mixed Liquor Volatile Suspend-
               ed Solids (MLVSS), MG/L     2500-6000
      0.5-2      Mixed Liquor D.O., MG/L       2-6
      30-75      Organic Loading, #BOD/1000 CF   100-250
    0.15-0.40     Food to Mass Ratio (F/M),
               #BOD/#MLVSS                0.4-1.0
    5000-15000    Return Sludge Concentration,
               MG/L                    10000-30000
     50-125     Return Sludge Rate, %Q         30-50
     75-150     Sludge Volume Index, SV1        50-100
     1.1-1.5     Oxygen Requirements, #O2/
               #BOD5                       0.9-1.3
      4-10      Oxygen Utilization, %O2 Sup-
               plied                        85-90
                                                    54

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Alternative A —Air activated sludge
physical characteristics
                    Item
Design Value
Secondary Lift Station
  Aeration Basin Pumps
    Horsepower installed                             1,200
    Horsepower utilized                               350
Blowers
  Aeration mode                               diffused air
  Air requirements, cfm (average)                    142,000
  Horsepower installed                                9,200
  Horsepower utilized                                5,600
Aeration Basins
  Basin type                                   rectangular
  Number basins                                       13
  Length, feet                                        355
  Width, feet      .                                    50
  Sidewater depth, feet                                  15
  Volume each,  MG                                    2
  Total volume, MG                                    26
  Detention time, hours                                 8.3
Secondary clarifiers
  Basin type                                   rectangular
  Number basins                                       22
  Length, feet                                         150
  Width, feet                                          40
  Sidewater depth, feet                                  10
 „ Surface area, each, ft2                              6,000
Waste activated  sludge  flotation thickeners
  Basin Type                                     circular
  Number basins                                       4
  Diameter,  feet                	                  40
Roughing Filter Concept

  Use of roughing filters in a two-stage biological treatment
scheme in conjunction with the activated sludge process has
been found to have the following advantages: Reduction in
applied aerator biochemical oxygen demand and consequent
reduction in  aerator volume;  biological buffer for the
activated sludge and subsequent prevention of aeration basin
upset due to toxic  loads; reduction  in  sludge  volume;
dampening of diurnal biochemical oxygen demand variation
on the aeration basin; and the imparting of dissolved oxygen
to the waste prior to  aeration.
  The literature contains numerous articles regarding plastic
media niters and the roughing niter concept. Manufacturers
have  published data and extensive literature on the plastic
media  roughing  filter.  These  data predict  biochemical
oxygen demand removals as high as 60 percent. Operating
experience at  other  locales,  though  limited,  verifies the
roughing  filter and air activated sludge process designs.
  Effective five-day BOD removal  is estimated to be 40
percent. If roughing  filters are used in conjunction with
intermediate clarifiers, it is estimated that BOD removals
would be  from 50 to 55 percent. Due to possible operational
problems with pure oxygen and filamentous organisms, the
roughing filter/pure oxygen activated alternative is analyzed
herein  with  intermediate  clarifiers.  The  conventional
aeration alternative with roughing filters does not incorpo-
rate intermediate clarifiers.
  The  following   illustrates the  physical characteristics
utilizing roughing filters for both the air activated sludge and
pure oxygen activated sludge systems.
.Alternative B—Pure oxygen activated sludge
 physical characteristics

 	Item	Design Value
 Secondary lift station
  Aeration Basin Pumps
    Horsepower installed                             1,200
    Horsepower utilized                               350
 Oxygen generation and storage
  Oxygen absorption efficiency, percent                85-90
  Installed oxygen supply, tons per day'                  150
  Oxygen demand, average daily
    flow and average month
    BODs, tons per day                                91
  Oxygen demand, average daily flow and
    maximum month BODs, tons per day                110
  Oxygen standby storage, tons                         480
  Horsepower installed                              6,000
  Horsepower utilized                               2,000
 Oxygenation tanks
  Mode                                   surface aeration
  Basin type                                   rectangular
  Sidewater  depth, feet                                 17
  Total volume, MG                                   8.4
  Detention  time, hours                                2.7
  Horsepower installed                              2,400
  Horsepower utilized                               2,000
 Secondary clarifiers
  Basin type                                   rectangular
  Number basins                                      22
  Length, feet                                       150
  Width, feet                                         40
  Sidewater  depth, feet                               12-14
  Surface area, each, ft2                             6,000
 Waste activated sludge flotation thickeners
  Basin Type                                     circular
  Number basins                                       4
  Diameter,  feet	40_

Air  Activated Sludge

  The  air  activated sludge process  is well  known and
 therefore will not  be discussed in any detail. The costs
 associated with the enumerated physical characteristics for
 the air activated sludge facility include provisions for plug
 flow, step feed, and complete  mix. In addition, costs for
 covering the aeration basins and scrubbing the foul air for
 odor control  are included.

Pure Oxygen Wastewater  Treatment  in
 Closed Tanks

  The use of pure oxygen in waste treatment is becoming
 popular in  the United States  and many  installations are
 being constructed utilizing pure oxygen in closed tanks. The
 process is commonly known as the Unox System, developed
 by the Union Carbide Company.
  This alternate system  involves the production of oxygen
 gas followed by oxygen dissolution in closed tanks generally
 constructed with substantial freeboard. Oxygen dissolution
 in the mixed liquor will be accomplished by the use of high
 speed surface aerators in the closed tanks which achieve 85*
 90  percent  utilization  of the  oxygen. The ability  of the
 oxygen  to  be  dissolved in the  mixed liquor efficiently
 reduces the  oxygenation detention time considerably over a
 conventional  air activated  sludge plant.  This allows for
 oxygenation tanks to be smaller in size or greater flows can
                                                         55

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be treated in the same volume of tanks. The pure oxygen
systems handle higher shock loads  with less effect  on the
mixed liquor basin and over-all plant. This occurs because
of the higher dissolved oxygen  level  which is  maintained in
the tanks.
Alternative C—Roughing (liter and air activated
sludge physical characteristics

                     Item
Design Value
Secondary lift station
  Roughing Filter Pumps
     Horsepower installed                               1,660
     Horsepower utilized                                1,000
  Aeration Basin Pumps
     Horsepower installed                               1,200
     Horsepower utilized                                 350
Roughing filters
  Basin type                                        circular
  Number basins                                         2
  Diameter, feet                                        145
  Media depth, feet                                      20
  Total volume, ft3                                 660,000
Blowers
  Aeration mode                                 diffused air
  Air requirements, cfm (average)                     80,000
  Horsepower installed                                5,200
  Horsepower utilized                                 3,100
Aeration tanks
  Basin type                                     rectangular
  Number basins                                         9
  Length, feet                                          355
  Width, feet                                            50
  Sidewater depth, feet                                   15
  Volume, each, MG                                      2
  Total volume MG                                     18
  Detention time,  hours                                  5.8
Secondary clarifiers
  Basin type                                     rectangular
  Number basins                                        22
  Length, feet                                          150
  Width, feet                                            40
  Sidewater depth, feet                                   10
  Surface area, each, ft3                               6,000
Waste activated sludge flotation thickeners
  Basin type                                        circular
  Number basins                                         4
  Diameter, feet                                         40
                   Alternative D—Roughing filter and
                   pure oxygen activated sludge
                   physical characteristics
                                        Item
                                                                 Design Value
Secondary life station
  Roughing Filter Pumps
    Horsepower installed                              1,660
    Horsepower utilized                               1,000
  Aeration Basin Pumps
    Horsepower installed                              1,200
    Horsepower utilized                                 350
Roughing filters
  Basin type                                       Circular
  Number basins                                         2
  Diameter, feet                                        145
  Media depth, feet                                      20
  Total volume, ft5                                  660,000
Roughing filter clarifiers
  Basin type                                    Rectangular
  Number basins                                        16
  Length, feet                                          150
  Width, feet                                            40
  Sidewater depth, feet                                   10
  Surface area, each, ft2                               6,000
  Flow capacity, each, MOD                             4.7
Oxygen generation and storage
  Oxygen absorption efficiency,  percent                 85-90
  Installed oxygen  supply, tons  per day                    75
  Oxygen demand, average daily flow and average
    month BODj, tons per day                            60
  Oxygen demand, average daily  flow and maximum
    month BODs, tons per day                          75
  Oxygen standby storage, tons                           240
  Horsepower, installed                                3,000
  Horsepower, utilized	1.000
                   Alternative D—Roughing filter and
                   pure oxygen activated sludge
                   physical characteristics
                   (continued)
                                        Item
                                              Design Value
                   Oxygenation tanks
                     Mode                                       Surface aeration
                     Basin type                                     Rectangular
                     Sidewater depth,  feet                                  17
                     Total volume, MG                                    4.3
                     Detention time, hours                                  1.4
                     Horsepower, installed                                1,200
                     Horsepower, utilized                                 1,000
                   Secondary clarifiers
                     Basin type                                     Rectangular
                     Number basins                                        22
                     Length, feet                                          150
                     Width, feet                                           40
                     Sidewater depth,  feet                                12-14
                     Surface area, each, ft2                               6,000
                     Row capacity, each, MGD                             3.4
                   Waste activated sludge flotation thickeners
                     Basin type                                        Circular
                     Number basins                                         4
                     Diameter, feet        	                             40
                                                            56

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Rotating  Active Diffusers (RAD)

  Each diffuser unit is  a 7'/4 hp motor driven disc-shaped
diffusion device having  a porous ceramic medium installed
in the anular space near the disc edge. As the RAD rotates
at a constant speed of 76-82 rpm in the mixed  liquor
approximately 2 feet off the tank floor, the hydraulic sheer
reduces the gas  bubbles  being  diffused  by the porous
medium to 50  microns.  Oxygen gas is transmitted through
the hollow drive shaft  to the diffuser  disc at the bottom,
then radially outward to the diffuser medium.
  The typical process schematic shows  the mixing action of
the diffusers which are rated at 1500#O2perday with a 90%
transfer to the mixed liquor. The tank mixing is achieved by
curved radial vanes on  the top and bottom surfaces of the
diffusers. This action prevents the settling  of the solids on
the tank bottom and provides adequate contact between the
mixed liquor and the diffused oxygen. The unique design of
the disc prevents any  buildup of scum or grease on  the
diffuser. A  disc  unit  was  removed  after 7  months of
continuous  operation and  flow tests  determined that no
plugging of the medium had occurred; there was only a
slight discoloration to the ceramic medium.

Pure oxygen wastewater treatment in open tanks
MAROX-Pure Oxygen System
Typical process schematic

  This method, utilizing fine bubble diffusion, is capable of
reacting extremely fast to changes in demand as oxygen,
instantaneously sensed and indicated through the  use of
dissolved oxygen probes and analyzers, is fed  directly into
the diffuser and then directly into the mixed liquor. The
time elapsed from a change in oxygen demand in the tank
until  a change in  oxygen diffused by the dissolution
equipment is only a  matter of seconds.

Operational  Performance

  Typical performance of the MAROX System applied to
municipal wastes is shown in the accompanying data.* The
municipal plant data was observed  in full-scale pilot and
demonstration plants treating  primarily domestic  waste
during 1973 through 1975. ('Supplied by MAROX manu-
facturer.)
Detention Time, Hours
Biomass Loading, F/M, Ib BODs/
  day/lb MLVSS
Organic Loading, Ib BODs/day/
  HOOOcf
Mixed Liquor TSS, mg/1
Mixed Liquor VSS, mg/1
Recycle TSS  RAS,  mg/1
Water Temperature, °C
SV1
SRT, days
Clarifier Overflow, GPDPSF
Oxygen Usage, Ibs O: supp/lb
  BODr
      installations
    ABC
   1.1   2.0   1.9
              D
             2.3
  1.02  0.71   0.56  0.59
  244
 4,743
 3,886
  133
3,730
3,060
  141
4,859
4,217
12,221 11,39013,461
  19.0  15.6   15.7
  67.8
   6.2
  617
  79
  3.5
 577
  78
  7.5
  614
  110
3,846
3,110
9,870
 16.0
  84
  6.8
  523
  0.92  1.12   1.11  1.37
                                                                    COUM.IUIIII
Schematic flow diagram cryogenic oxygen plant plant no. 2
Pure oxygen waste treatment in enclosed tanks

Pure Oxygen Wastewater Treatment in
Open  Tanks

  While most pure oxygen wastewater treatment installa-
tions currently being constructed  utilize the closed  tank
concept, another pure oxygen  dissolution technique has
been evolving in the United States. It is a diffuser system
which generates very fine pure oxygen bubbles deep in the
mixed liquor, achieving 90% or greater oxygen transfer. The
process, known as  the MAROX  System,  has  been
developed by the FMC Company of Chicago, Illinois.
  Covered tanks are not needed because of the efficient
transfer of oxygen  in the mixed liquor and  since there is
little surface agitation, no more than two feet of freeboard is
necessary.

MAROX  System

  The system is comprised of three major components :
   1. A source of pure oxygen gas such as on-site cryogenic
     oxygen supply system. The cryogenic process has been
     in wide use for many years in the United States with
                                                        57

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   thousands of existing industrial installations.
2. An  oxygen dissolution  system  utilizing  "Rotating
   Active Diffusers" (RAD).  Pure  oxygen gas,  in the
   form of minute (50 micron) bubbles, is simultaneously
   introduced deep into mixed liquor via  RAD  to
   accomplish the mass oxygen transfer.
3. The system is controlled by  an  automatic dissolved
   oxygen control system that accurately monitors and
   controls  the  DO level. DO sensors are strategically
   located in the mixed liquor to automatically regulate
   oxygen  flow  to  the diffusers.  Mixed   liquor  is
   constantly  monitored  and  consistently  maintained
   within 1.0 mg/1 even through diurnal flow  variations.

Upgrading Existing Air Diffuser Systems

   The  MAROX  system is  appropriate for upgrading
treatment facilities.  Most existing aeration  tanks can be
utilized by  the addition of  the  diffuser equipment and a
source  of oxygen gas. With minimal  modifications to the
tanks,  the  capacity of the mixed  liquor  basins can be
increased several fold. A recent conversion at a treatment
facility in  Colorado  was  completed in 6  weeks  after
fabrication of the diffusers. The tank was upgraded from a 3
mgd air diffuser system to a 10  mgd MAROX system.
   Thirteen  RAD diffusers  replaced 21 air diffusers in a
basin 210 feet long,  25 feet wide and 17 feet deep. Six RAD
diffusers were paired at 21-foot intervals at the inlet end of
the tank and monitored by  a  DO probe.
   A second DO probe monitored the next four  diffusers
which were mounted singly at 21-foot intervals in the center
of the basin.

   A third  probe monitored the remaining three  diffusers
which  were  spaced uniformly at the  outlet end of the tank.

Observations of the MAROX System

   I. The system appears to be very simple to operate since
     the  oxygen  feed rate  to  the   diffuser  system is
     automated  to  the  dissolved oxygen  of the mixed
     liquor.
   2. Open  tank construction with  minimal freeboard
     means savings in capital construction costs compared
     to closed tank systems.
   3. This  system appears ideal  in pre-aeration  or pre-
     treatment  modes  because  each  diffuser  unit is
     complete in itself, the spacing can be arranged to put
     the  greatest oxygen  supply  in areas  of  greatest
     demand.
   4. Existing aeration tanks can be upgraded with  minimal
     modifications in a short period of time.
   5. The danger of explosive mixtures associated with pure
     oxygen is minimized with the open tank  system when
     compared to the closed tank system.

Conclusions

Land Requirements

   Like many waste treatment facilities in highly urbanized
areas, the agency's two treatment facilities, which comprise
approximately 100 acres each, are surrounded by residential
and industrial development. Because of this, it is important
 to  conserve  all usable land  space  when  expanding for
 projected flows of 320 mgd in the year 2000, by employing
 processes which can  concentrate treatment  in  compact
 facilities.  In  addition, we must provide odor abatement
 facilities and incorporate these features into new construc-
 tion whenever possible. The pure oxygen activated  sludge
 process utilizes the least amount of land.
 Land requirements

      Alternate            Acres
         A                13.1
         B                10.7
         C                13.9
         D                11.5
           Acres for
           Structures
              8.6
              6.2
              9.4
              7.0
 Secondary Sludge Generation
   While it would appear that Alternate  D generates the
 least amount of sludge, there  is  no difference between
 Alternates D and C, since the intermediate clarifier sludge
 returns as primary sludge. The difference in secondary
 sludge generation is not significant in the selection of the
 alternate process.
SECONDARY SLUDGE GENERATION • 75 MGD
(pounds dry solids per day)
Secondary Sludge Generation
Alternate
A
B
C
D
Raw
(dry ft/day)
96,000
96,000
77,000
71,000
Digested
(dry #/day)
54,000
54,000
46,000
42,000
Digested*
(cubic yards/day)
142
142
121
110
'Assumes 20% solids with 90% solids capture from centrifuges
Energy Requirements
  The projects analyzed  require significant  amounts  of
energy to operate; much of the energy will be available on
site in the form of  digester (methane gas from biological
treatment alternatives.
  In  the  analysis,  equipment  (installed) horsepower  is
estimated to exceed the horsepower utilized  daily. This is
normal practice to insure sufficient power and equipment in
cases  of equipment failure, maintenance work, and peak
load periods. Much of the utilized horsepower needs may be
met by use of digester gas for fueling  engines, boilers,
incinerators,  and  other  equipment  for the  biological
treatment alternatives. Not all equipment can be operated
on this fuel, and alternative power sources are needed  to
ensure continuous,  uninterrupted treatment and pumping
processes during normal circumstances, during emergen-
cies, and during natural disasters.
Energy requirements


          Installed    Utilized
Alternate Horsepower Horsepower
     A          12,609   8,406
     B           8,745   5,830
     C           9,889   6,593
     D           7,500   5,000
Horsepower
   from
Digester Gas
    2,923
    2,423
    1,943
    2,796
 Purchased
Horsepower
   5,483
   3,407
   4,650
   2,204
                                                       58

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Cost Analysis
  A detailed cost analysis was performed on each of the
alternatives set forth herein. All costs are based on the same
construction cost index. Capital costs were developed from
the construction bid for the SO mgd activated sludge plant
currently   under  construction  at  Plant No.  1,  from
manufacturers' quotes, and from other similar construction
jobs. The costs  are  estimated for a  75  mgd  increment of
secondary  treatment.  They  include a  secondary pump
station, secondary treatment basins and  clarifiers, roughing
filter and aeration basin covering for odor control, air or
oxygen supply  facilities,  sludge  thickeners, yard work,
instrumentation, construction  of  an   electrical service
entrance,   and  emergency  power  generation.  Oxygen
generation facilities  considered are cryogenic units, which
are more economical than other oxygen generating facilities
for quantities necessary herein.
Capital Cost
  The  total  project  capital  cost  was  determined  by
estimating the construction cost and then adding 43 percent
to cover contingencies, engineering, legal and administra-
tive costs, and interest during construction in conformance
with Federal guidelines.

Definitions:
BOD;—Biochemical oxygen demand -  5 day
SS—Suspended solids
F/M—Food  to microorganisms
MG/L (mg/1)—Milligrams per liter
MLSS—Mixed liquor suspended solids
DO—Dissolved oxygen
MG—Million gallons
MGD (mgd)—Million gallons per day
ft2—Square feet
ft'—Cubic feet
                             Recommended Project
                               On the basis of the analysis presented, an evaluation of
                             alternatives has shown the pure oxygen activated sludge
                             process to be the most cost-effective for secondary treat-
                             ment.
                               Pure oxygen activated sludge offers an 18 percent savings
                             in project cost over the next cost-effective alternative. The
                             recommended alternative  provides a degree  of treatment
                             which will meet secondary treatment effluent quality limits
                             and will provide a cost savings for maintenance, operation,
                             and  power  over  the conventional  aeration secondary
                             treatment alternatives. Digester gas generated from the 75
                             million gallons per day treatment scheme will provide 5,830
                             horsepower. This recommended alternative also provides a
                             savings in land  utilization over other alternatives.
                               The  costs enumerated  for  the  pure oxygen activated
                             sludge  process are based  on the closed tank  system. For
                             construction competition purposes, relatively few addition-
                             al drawings are needed when both the closed tank and open
                             tank oxygen systems are under consideration.  Only the
                             oxygenation tanks and  associated electrical requirements
                             are different, while the oxygen  gas production and the final
                             clarification  systems  are  similar.  For example,  only  8
                             additional  design   sheets  were  required to determine
                             competitive  costs recently for  a proposed 20 mgd oxygen
                             treatment facility.
 Monetary cost of alternatives
                                          Alternate A
                                         Air Activated
                                            Sludge
                            Alternate B
                              Oxygen
                             Activated
                              Sludge
                                     Alternate C
                                      Roughing
                                        Filter
                                         and
                                    Air Activated
                                       Sludge
                                     Alternate D
                                     Roughing
                                       Filter
                                     and Oxygen
                                     Activated
                                       Sludge
 Construction cost
 Annual costs
  Capital Recovery
  Maintenance
  Operation
  Power
  Chemicals
  Interim Sludge
     Disposal
 Total annual cost
$/MG
$/MG
$/MG
$/MG
$/MG
$/MG

$/MG
$49,705,000

       233
        29
         9
        43

        34

       349
42,193,000

      203
       25
        9
       24
        I
       34

      296
49,682,000

      233
       29
       10
       33

       32

      338
51,369,000

      244
       30
       10
       23
        I
       32

      340
                                                         59

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Studies of Artificial  Aeration

in  the  Lithuanian  SSR.

Skirckiavichus A.L.
The  Kaunas  Polytechnic
Institute of Snechkus  A.

  All our efforts to treat wastewaters result in pure water
and rivers useful for beneficial purposes. Therefore further
treatment of effluents discharged from treatment plants may
be necessary. The effluent residual BOD presents considera-
ble loading for receiving waters, especially if they are not
large.
  For  example  an  average  industrial  town  (on  the
Lithuanian SSR  scale)  produces 50,000  cu.m. of waste-
waters having a  BOD5 700 mg/1 or 35 T. BOD5 per day.
This BOD value is typical for wastewaters discharged by
our towns having food-processing industry.  At 95 percent
treatment efficiency residual  BODs  will be 1,75 T. per day
and equal to load produced  by 32,000 inhabitants.
  Attention should be given to river pollution caused by
urban storm waters,  drainage waters and effluents from
small agricultural areas, where chemicals and fertilizers are
widely used their load may be significant.
  Biological treatment process also takes place in rivers
where all these pollutants go into  with natural waters or
sewage and therefore it  should be subjected to adequate
control.
  During the  dry summer period at high  temperatures or
the winter period  when ice  cover inhibits natural surface
aeration  temporary bad river conditions may bring to
naught all attempts and expenditures spent on wastewaters
treatment.
   Artificial aeration is a method which prevents anaerobic
in the river and promotes destruction of contaminants. The
studies of artificial aeration have  been conducted by the
Kaunas Polytechnic Institute and the Ministry of Municipal
Economy since 1971.
   The investigations were conducted at the Nevejis River
polluted by insufficiently treated wastewaters of Panevejis-
town. For these purposes the experimental unit "NEVEJIS-
 1" with mechanical C-16 type aerators developed by Vitols
O. and Resinsh was established at the river. The capacity of
an aerator is  2.2 kw. They  were mounted from 4 to 9 in
number on metal frame which  was fixed  to supporting
pontoons. The river width in this region is 16-20 m, frame
length is  12 m. So the cross-section of the river was wholly
included into  aeration zone.
  The DO concentrations have been measured by electro-
chemical DO analyzer of UT-6803 type developed by Tartu
State University.
   Special studies  were  conducted  to select DO sampling
point at cross-sections, to determine reiteration of measure-
ments and  to choose upstream and downstream cross-
sections for sampling.
   Detailed measurements of DO were made in a number of
cross-sections  at   5-10  m. distance  downstream  and
upstream from aerators when they were in operation and
out of operation. Variation-static method was used to work
up data and to estimate accuracy of  measurements.
   Downstream cross-section for sampling  has been selected
in such  a  way  that  the DO  concentration  variation
coefficient didn't exceed the value of the coefficient for the
same cross-section under natural conditions (aerators are
turned  off).
  On the basis of analysis of static characteristics  it has
been found that samples to be taken at the depth of 0.3 m;
reiteration of  measurement should  be more than 5; the
duration of five time measurement shouldn't exceed 4-5
min.,  downstream  sampling  point should  be at   50m.
distance  from an aerator. Upstream sampling point is
assumed to be  at  the same distance from an aerator
proceeding from convenience in sampling and calculations.
Measurements were made at cross-sections taking into
account the  flow time between sampling  points.
  For comparison of results obtained from particular tests
under different conditions data have been converted to
standard conditions (river temperature is 20°C, 0 percent
DO saturations,  pure water, 760 mm Hg pressure).
  If rotor is submerged at 1,0 m depth  and aerators are
mounted at 3m distance from each other average oxygena-
tion capacity at standard conditions is 1,14 kgOz/kwh. This
value is lower than those obtained according to data which
were reported by   American (1,34  kgO2/kwh) and  Ger-
man (1,37 kgO/kwh) investigators.  It is evident that the
difference is negligible. It can be attributed to low flow rate,
as it has been found efficiency of artificial aeration increases
with increasing flow rate.
  In practice this efficiency was obtained during tests on
turbine suction aerators having a capacity of 30kw.
  DO  saturation should  be better under  actual   river
conditions in comparison with that in tanks under steady-
state conditions, due to a new dosage of water with high
saturation deficit of DO which reaches aerator all the time.
But oxygenation capacity of aerators of all types is  lower
than that achieved  under non-flow conditions. Similar
results have been reported by foreign scientists Huntre J.V.
Whipple W. et al. Probably it may be explained by the fact
that there is no standard method for evaluation of aerator's
efficiency. Of course reasons will be further investigated, but
at present while designing this fact should be considered and
aerator efficiency index which is about 0,33-0,4 should be
introduced into coefficient..
  Studies of barbotage aeration also were conducted at the
experimental  unit.  Aerators- plastic corrugate drainage
pipes with a diameter of 50mm and a length of 2,20m- were
put on branch pipes welded to a steel pipeline  which was
laid  across  the river.  1080 openings with a diameter of
1,5mm  were made  at each meter along aerator's length.
Total openings area on one running meter of the pipe is
0,00191 sg.m. Air was provided by air blower approximate-
ly 60 cu.m.  in hour per one aerator. Efficiency of oxygen
consumption is 2.2 percent. Average air rate at outlets is
4m/sec.  Oxygenation  capacity  of  barbotage aeration at
standard conditions is 0,99kg O2/kwh or 13 percents lower
than that of mechanical aeration.
  Barbotage aeration has such shortcoming as the  noise
which is produced by air blowers. This disadvantage limits
its application in densely populated areas of the Lithuanian
SSR. The construction of special buildings for air blowers
increases the construction cost of artificial aeration  unit.
  As a  result of DO tests carried out  at  weirs it was
concluded  that  weirs  for artificial aeration  should  be
constructed with a height of to 1,0 m. Weir should be  with a
free-spilling jet  and  reaches conjugated  according to
                                                      60

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submerged hydraulic jump.
  Studies of artificial aeration were conducted at PpK 70-
BO-100  Kruosta  hydraulic  turbine.  Air was supplied
through pipes in upper cap of a turbine which connect zone
of discharging with atmosphere.
  In the course of aeration the DOconcentration varied in
the range from 0,55 to 1,70 mg/1. The loss of a unit capacity
was  ranging from 4,8  to  8,7  percent during artificial
aeration.
  Average oxygenation capacity under standard conditions
is  2,58kgCh/kwh.  The efficiency of artificial aeration  by
hydraulic  turbine  is higher than those obtained by other
methods.
  Investigations showed that above  mentioned value of
capacity loss was  conventional. Discharge which  doesn't
pass through hydraulic turbine due to artificial aeration,
remains in head race and naturally conserves its potential
energy. So when not all of the turbines are in operation and
there is no dummy discharge saved flow rate passes through
another hydraulic turbine. Thus amount of energy generat-
ed by hydropower station  as a whole  decreases slightly.
Only amortization of units increases due to their operation
together for longer  time than  that  without aeration.
Therefore aeration efficiency  of the  hydropower station
estimated by this method is up to 12,94kgO2/kwh or 17,86
kgO2/kwh under standard conditions.
  The  results of the  studies  conducted to determine the
effect of artificial aeration on self-purification properties of
the  receiving waters didn't  show improvement  in self-
purification properties. Variations in BOD and COD values
were nearly the same during artificial aeration as well as
without it and didn't indicate an obvious relationship.
  The same results were achieved during microbiological
tests. Only number of anaerobic bacteria decreased slightly.
Index of testing on glander ranged equally with aerators in
operation as well as out of operation: ranging from 2,6-3,0
in the region in front of aerators to  2,2-2,75  at the 5km
potion behind cross-section of artificial aeration.
  As a result of analysis  of data taking account of literary
data the following conclusion can be drawn: under aerobic
conditions the  increase in  the DO concentration doesn't
intensify self-purification process significantly.
  It conforms to Phelpth-Striter theory. According to it the
rate  of BOD removal is directly proportional to BOD value
and is independent of DO content in water. Of course it may
exist until anaerobic conditions will occur which inhibit self-
purification process. According  to Velner CH A,  Melder
Ch.A.  and  Laene A.A. maximum  rate  of  aeration  is
determined at DO concentration ranging from  1,5 to 2,5
mg/1. Probably the DO concentration shouldn't be less than
above given values below the place of wastewater discharge
under extreme conditions (low flow rate, high temperatures,
ice cover etc.)
  If anaerobic conditions exist in front of artificial aeration
zone, aeration  promotes self-purification process. Some-
times it requires a  certain time depending on the degree of
anaerobics in the  region in front of the cross-section of
reaeration. Of course during  artificial aeration the process
restores more rapidly than that under natural  conditions.
  The effect of artificial aeration on oxygen regime in the
river is estimated by comparison of slopes of oxygen curves
(mgO2/ I/km) prior to and after artificial aeration.
  The definition "slope of oxygen curve" (mgO2/l/km) in
our  view reflects  fully the dissolved oxygen saturation
process in conjunction with reaeration.
  As  a result of investigations it has been found that the
slope  of oxygen  curve increases slightly (7-11%) if artificial
aeration unit is located in the descending potion of oxygen
curve. It may be attributed not to increase in the rate of self-
purification   process  and  oxygen  consumption  but to
decrease in  the  rate of natural surface reaeration due to
increased saturation of water with oxygen.
  Artificial  aeration  is  graphically shown  in  Figure  1
considering  all above  mentioned conclusions.
  Prior to wastewater discharge to receiving waters (point
1) BOD value is normal and DO concentration's high and
near  saturation  value.  Pollutant concentration increases
during  wastewater discharge. Intensive  self-purification
process starts below the point of discharge. BOD concentra-
tion reduces and natural surface reaeration  can't supply
sufficient amount of oxygen.  The oxygen  curve descends
rapidly and intersects line of desired minimum concentration
(1,5-2.0 mgO/1) at point  2.  Normal aeration process is
broken, fish is killed, self-purification process is inhibited
considerably.
  At  point  3— oxygen supply  is  exhausted, anaerobic
digestion process occurs. BOD concentration doesn't reduce
and even increases due  to secondary pollution.
  At  a certain distance at point 4 air supply again exceeds
oxygen consumption its concentration restores and reaches
level  of desired  minimum concentration at point 5, above
which self-purification process takes place under  normal
conditions. Thus under natural conditions  normal process
of self-purification doesn't occur in the river potion with L
length, between  points 2 and 5.
  If artificial aeration is applied at  point  2,  DO concen-
tration increases BOD removal goes on. If it is necessary
artificial aeration is applied at several cross-sections (e.g. at
point  3, 4)  until  oxygen curve reaches  point  5.  Self-
purification  process goes on  all the time under  normal
aerobic conditions  and ends somewhere at point 6, which is
located nearer than that under the same conditions without
artificial aeration.
  Of  course pollutants concentration exceeds normal value
in the region between points 2 and 6, it isn't so dangerous
due to presence  of oxygen. If we must select either "dead
stream" that is with zero. DO concentration of "alive river"
although it doesn't meet water quality standards, the latter
should be chosen. As we have already seen such alternative
may arise with  any small stream, even  if we have good
wastewater treatment  plants.
  Wastewater  treatment plants can't  be  replaced  by
artificial aeration and  therefore we shouldn't exaggerate its
possibilities.  However more  attention should be paid to
artificial aeration as an economical and effective method of
a partial solution  to river DO problems  at present  day
growth of pollution.
  The Kaunas Polytechnic Institute continues studies of
artificial aeration. The design  of powerful summer unit of
artificial aeration has been performed and it should prevent
formation of regions with anaerobic  conditions in the
Nevejis River until wastewaters discharged by Kedainiay
town  will receive  sufficient treatment.  Unit's capacity  is
600kw. Oxygenation  capacity is approximately  7000kg
DO/day. At  present the  possibility of constructing the
aeration unit in  1977  is being considered.
                                                        61

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      a.
Ml/A
    Fig. 1. Self-purification process in overloaded river.
    a. River aeration;
    b. Artificial aeration;
    1. DO concentration;
    II. BOD concentration;
    III. Desired minimum DO concentration.
Wastewater  Treatment
Concerns  of the Organic
Chemicals Industry  in  the
United  States
Carl E. Adams, Jr., Ph.D., P.E.
President
Associated Water & Air
   Resources  Engineers,  Inc.
Nashville,  Tennessee

Billy T. Sunnier, P.E.
Immediate Past President
American  Consulting Engineers Council
Vice President
Barge, Waggoner,  Sumner and  Cannon
Nashville,  Tennessee

July 1976

I. Introduction

  The organic chemicals industry is the most complex and
diversified  industry in  the  United  States. It not only
generates thousands of  different  products,  but even
produces at different plants identical chemicals by different
processes.
  Synthetic organic chemicals  are products derived from
naturally-occurring raw materials—primarily from petrole-
um, natural gas, and coal—that have undergone at least one
chemical conversion. Originally, coal was  the primary raw
material for the organic chemicals industry, but in the last
20  years,  it has  been  replaced  by  petroleum-based
feedstocks because, even though the price of coal is less than
one-half that of most fluid feedstocks, the handling and
processing of fluids is more economical. Moreover, the
mining  of  coal  is far  more labor-intensive than the
extraction  of  fluid  fuels  from  the  earth.  The term
"petrochemical"  is commonly used to refer to all organic
chemical products derived from petroleum fractions and by-
products or from natural gas constituents.
   Within the last 10 years, there has been an extraordinary
simplification of  numerous   organic  syntheses,  chiefly
because of unique developments in catalysis and automatic
control. This, combined with the construction of larger and
larger production facilities, has resulted in a drop in the
price of organic chemicals that  would  not  have been
thought possible a few years ago.
   This trend toward lowering production  costs is counter-
balanced by a rapidly developing crisis in the organic
chemicals industry: the diminishing availability of economi-
cal raw materials. The chemical manufacturers are now
paying more and more for crude oil and natural  gas—a
situation that  is expected to become more  severe.  In
addition  to  this  economic  problem,  the industry   is
confronted with the cost of complying with the pollution
                                                     62

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 abatement goals established by the federal government.

II. Categorization of the Organic Chemicals
Industry

   There has been an effort in the United States to establish
 effluent  discharge  limitations  for  each major  industrial
 product.  For some industries, such  as pulp and  paper,
 relatively broad effluent  guidelines that apply to certain
 segments of these industries can be established.  However,
 this is  impossible  for the organic chemicals industry in
 which increasingly complex technologies produce a diversi-
 ty of interrelated chemicals by a variety of processes. The
 water usage and subsequent  discharges of wastewater are
 directly related to this mixture of products and processes.
 Therefore,  the federal government has prepared effluent
 limitations  for the organic chemicals industry as a whole
 with  subcategories that are related to  the manufacturing
 process and the extent of water usage within the process.
 There are four major subcategories:

 Subcategory A: Nonaqueous Processes
   This subcategory is limited to processes in which there is
 minimal  contact  between water  and  the  reactants  or
 products; water is not required as a reactant or diluent and
 is not generated as a reaction product. The water usage in
 this category  would result only from necessary washes or
 catalyst  hydration.

Subcategory B: Process Water Contact as Steam Diluent or
Adsorbent
  This subcategory is limited to processes in which water is
utilized in  the  form of  dilution   steam,  direct  product
quench, or adsorbent for effluent gases in reactions that are
all vapor-phase over a solid catalyst. Most processes in this
subcategory utilize an  adsorbent  combined with  steam
stripping of chemicals for purification and  recycling.

Subcategory C: Aqueous  Liquid-Phase Reaction Systems
  This  subcategory  includes  processes  in  which  the
reactions are liquid-phase with the  catalyst in an  aqueous
medium. Continuous regeneration  of the catalyst requires
extensive water usage and in some cases substantial removal
of inorganic by-products. This subcategory also  includes
processes in which water is involved in the final purification
or neutralization of products.

Subcategory D: Batch and Semicontinuous Processes
  This subcategory includes  the  processes in which the
reactions are liquid-phase with aqueous catalyst systems; in
which very rapid cooling makes it necessary to add contact
quench water or ice; or in which the reactants and products
are transferred through the various processes by gravity
flow,  pumping,  or pressurization.  This  subcategory  also
includes processes in which much of the materials handling
is manual; in which solids-liquid separations are common
and employ filter presses and centrifuges; or in which air or
vacuum ovens are used for drying products: a major source
of wastewater  results  from cleaning the  noncontinuous
production equipment.
  All effluent limitations and treatment technologies for the
organic chemicals industry were defined on the  basis of
these  four subcategories. In addition, Subcategories B and
C were further subdivided according to raw waste loads by
groups—B-l,  B-2, C-l,  C-2, C-3 and C-4—that consist of
product/process segments with similar ra.w waste load
characteristics for the  major  pollutant parameter, bio-
chemical oxygen demand  (BOD).

III. WASTEWATER CHARACTERISTICS FOR THE
ORGANIC CHEMICALS INDUSTRY
  Because  of the diversity  of the  organic chemicals
manufacturing processes,  practically  every  significant
pollution parameter exists at one plant or  another. Some
waste streams may contain only two or three significant
parameters, whereas others may contain as many as 50 or 60
significant  constituents. After extensive literature  review
and  numerous  field  surveys,  the federal  government
concluded that there are only 27 that significantly affect the
quality  of surface waters (see Table  1). Of course, the
effluent limitations include the usual pollution indicators:
biochemicals  oxygen demand (BOD), chemical  oxygen
demand  (COD), total  suspended  solids (TSS),  etc.  In
addition, there are other limitations  that, for the most part,
pertain to dissolved organic pollutants in process wastewa-
ter. No specific limitations were proposed  for pollutants
associated  with non-contact  wastewater like  boiler and
cooling-tower  blowdown  because  these  waste  streams
primarily contain inorganic materials and it is difficult to
allocate such wastes to  specific processes in multi-product
plants.
  Other  parameters  considered   include   total  organic
carbon, ammonia, cyanide, extractable oils and grease, and
various heavy metals. These were generally found to be in
concentrations substantially lower  than those that  would
require  specialized  end-of-pipe treatment,  i.e., treatment
that is not an integral part of the industrial process.
  Summaries of the amount of flow, BOD and COD for
Subcategories A, B, and C are shown in Tables 2,  3, and 4,
respectively.  There is insufficient data  at this time from
Subcategory D processes; however, Table 5 does show some
data from a batch organic chemical plant producing azo
dyes.
Table 1
Significant pollutant parameters for the organic chemicals industry
General Parameters
  1. Biochemicals Oxygen
   Demand (BOD)
  2. Chemical Oxygen Demand
   (COD)
  3. Total Suspended (Nonfilter-
   able)
   Solids (TSS)
  4. Total Dissolved (Filterable)
   Solids (TDS)
  5. pH
  6. Acidity
  7. Alkalinity
  8. Hardness - Total
  9. Calcium - Total
10. Magnesium - Total
11. Chloride
12. Sulfate
13. Color
14. Oil and Grease
Organic Pollutants and Nutrients
15. Totals Organic Carbon (TOC)

16. Ammonia Nitrogen

17. Total Kjeldahl Nitrogen (TKN)


18. Phenols

19. Cyanide - Total
20. Phosphorus - Total
Metals
21. Zinc-Total
22. Copper-Total
23. Iron  - Total
24. Chromium - Total
25. Cadmium - Total
26. Cobalt - Total
27. Lead - Total

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Table 2
Summary of raw waste load data
Subcategory A - nonaqueous processes
Product/Process

BTX Aromatics
(Hydrotreatment)
BTX Aromatics
(Solvent Extractin)
Cyclohexane
Vinyl Chloride
Mean Value
Flow
liters 1 1000 kg

114.0

504.0
No Discharge
2,004.0
873.0

gal 1 1000 Ib

13.6

60.4
240
105.0
BOD
kg /1000kg

0.10

-
.
0.10
COD
(IbllOOO Ib)

0.31

-
0.12
0.22
Table 3
Summary of raw waste load data by Subcategory group
Subcategory B - processes with process water contact as steam diluent or adsorbent
B-l Product/Process

Ethyl benzene
Ethylene and Propylene
Butadiene (from ethylene)
Methanol
Acetone
Vinyl Acetate
Formaldehyde
Ethylene Oxide
Ethylene Dichloride
Vinyl Chloride (from
ethylene dichloride)
Methyl Amines
B-l Mean Value
Flow
liters 11 000 kg
317
2,961
1,693
417
1,460
234
1,093
617
800

2,802
3,661
1,460

gall 1000 Ib
38
355
203
50
175
28
131
74
96

336
439
175
BOD
kg /1 000 kg
0.13
0.35
0.63
0.49
0.26
0.04
-
0.7
-

-
0.48
0.38
COD
Ob /WOO Ib)
1.86
2.36
2.04
0.94
1.10
0.13
-
6.48
4.84

7.66
12.8
4.0
 B-2 Product/Process

 Acetaldehyde (from
   ethanol)                                  13,344                 1,600                  1.12                   2.48
 Butadiene (from
   n - butane)                                9,674                 1,160                  2.96                   3.23
 Acetylene                                   4,679                   561                  1.92                   5.95
 Styrene                                    14,453                 1,733                  1.00                   3.74
   B-2 Mean Value                          10,541                 1,264                  1.75                   3.85
                                                              64

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Table 4
Summary of raw waste load data by subcategory group
Subcategory C - aqueous liquid phase reaction systems
C-l Product/ Process
Coal Tar (pitch forming
Acetic Acid
Acrylic Acid
Ethylene Glycol
Terephthalic Acid
C-l Mean Value
C-2 Product/ Process
Acetaldehyde (ethylene and
oxygen)
Phenol and Acetane
(cumene process)*
OXO Chemicals
Coal Tar (distillation)
Caprolactam
C-2 Mean Value
C-3 Product/Process
Acetaldehyde (ethylene and
air)
Anilene
Bisphenol A*
Dimethyl Terephthalate
C-3 Mean Value
C-4 Product/ Process
Acrylates
P - Cresol*
Methyl Methacrylate
Terephthalic Acid (nitric
acid process)
Tetraethyl Lead
C-4 Mean Value
* Phenols raw waste load - 10
Flow
liters /WOO kg
1,043
4,170
3,962
4,871
1,551
3,119


509

2,335
3,503
3,336
10,842
4,103


751
1,585
559
2,252
1,284

23,819
10,767
1,668

5,496
100,000
28,366
kg/ 1000 kg (lb/1000 Ib)

gall 1000 Ib
125
500
475
584
186
374


61

280
420
400
1,300
492


90
190
67
270
154

2,856
1,291
200

659
12,000
3,401

BOD
kg/1000 kg
0.35
0.74
0.34
0.82
0.56


1.9

5.6
3.2
2.8
1.6
3.03


26.6
.
..
24.4
25.5

47
123
45

59
-
68.5

COD
(lb/1000 Ib)
0.06
0.78
1.64
8.76
1.72
2.59


5.8

11.0
4.25
8.7
4.0
6.75


44
21.2
17.1
38.2
30.1

118
256
386

104
110
195

Table 5
Summary of raw waste load data
Subcategory D—batch and semi-continuous processes
              Product/Process
Azo Dye (Batch)
 @  50% occurrence
  Mean Value
liters 11000 kg

   793,826
   114,395
   175,768
   361,329
 Flow
gall 1000 Ib

  (95,069)
  (13,700)
  (21,050)
  (43,273)
BOD         COD         TOC
    kg/1000 kg (lb/1000 Ib)
 79
220
 59
119
1,850
1,075
  175
1,033
790
450
 60
433
                                                            65

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IV. Wastewater Control and Treatment
Technology

  Three distinct levels of technology are being utilized to
reduce the concentrations of various pollutants to the levels
required by law and are defined as follows:

  1. Best Practical Control TecKnology Currently Availa-
     ble (BPCTCA), which represents the quality that must
     be achieved no later than July  1, 1977.
  2. Best Available  Technology Economically Achievable
     (BATEA), which is more stringent than BPCTCA and
     will be required by July 1, 1977, in those situations in
     which water quality has  deteriorated so  much  that
     improvements beyond BPCTCA are necessary. This
     technology will be required for all treatment facilities
     by 1983.
  3. Best  Available Demonstrated  Control Technology
     (BADCT), which is an improvement over  BPCTCA
     that is required for all new industrial plants generating
     an effluent for the first time.

  Effluent limitations for  1977 and new source performance
standards (BPCTCA and  BADCT, respectively) were based
upon three significant pollutant indicators:  BOD, TSS, and
phenols. The effluent limitations for  phenolic compounds
were applicable only to the cumene process (bis-phenol A
and  p-cresol   manufacturing).  In  addition,   the  1983
performance standard (BATEA) specified COD  as well.
  The  1977 standard (BPCTCA) specifies that a biological
process (activated sludge,  trickling filter, aerated lagoon, or
anaerobic lagoon) be used to provide end-of-pipe treatment.
With any of these processes,  there  must  be appropriate
pretreatment for pH control, equalization, oil and grease
removal,  etc.,  in  order to  limit various waste loads  and
remove materials that might interfere with the performance
of the  biological system.  In some instances, however, a
combination of  physical  and chemical  processes,  (for
example, activated  carbon, ammonia stripping, chemical
oxidation, ion exchange,  and reverse osmosis) is allowed;
or,  if waste loads are  adequately reduced as part of  the
industrial process, then biological treatment is not required.
  The  1983 standard (BATEA) requires the addition of an
activated carbon process following the biological system in
order to  remove  those refractory dissolved organics that
have passed through the biological system as well as to
remove some biodegradable pollutants that have not been
adequately   removed  in  the  biological system. Effluent
suspended-solids reduction  utilizing filtration or coagula-
tion  may be required between the biological and carbon
systems.  Even  though the activated carbon  process  is
utilized, it  may  also be necessary  to have the  industrial
process include certain controls to reduce pollutants:  for
example,

  1.  Substitution of noncontact heat exchangers or direct
     contact water cooling;
  2.  Use of nonaqueous quench media as  a substitute  for
     water where direct contact quench  is  required;
  3.  Recycling of process water;
  4.  Reuse of process water (after appropriate treatment)
     as makeup  to evaporative  cooling towers  where
     noncontact cooling water is circulated;
   5.  Use of process water to generate low-pressure steam
      by noncontact heat exchangers in reflux condensers of
      distillation columns;
   6.  Recovery of spent acids or caustic solutions for reuse;
   7.  Recovery and reuse of spent catalyst solutions; and
   8.  The  use  of nonaqueous solvents for  extraction of
      products.

   The  end-of-pipe technology  for  new source standards
 (BADCT)  has  been  defined as the use  of biological
 treatment followed by suspended-solids removal by clarifi-
 cation  sedimentation or  by  granular media filtration.
 Exemplary in-plant controls such as the above are assumed
 to be applicable  as well. This is  particularly important  if
 constituents are present-that might be toxic to the biological
 system.

 V.  General Considerations  for End-of-pipe
 Treatment Technology   .

   The technologies which are now utilized in the organic
 chemicals industry in  the United States and the achievable
 treatment  level which have been  proposed  by the federal
 government are as follows:

 Biological Treatment  Performance
   The biological treatment techniques most commonly used
 by the organic chemicals industry are activated sludge and
 aerated lagoons. In developing its  guidelines for the organic
 chemicals  industry, the  federal government relied on the
 performance records  of a number of treatment plants (see
 Table 6).  Data from those judged  to be exemplary are
 summarized below:
 Exemplary Single-
 Stage and Multiple-
 Stage Treatment
 Plants
 Exemplary Single-
 stage Treatment
 Plants
                      COD     BOD    TOC   Effluent
                     Removal Removal Removal    TSS
                     percent  percent  percent  mg/Iiler
74
                        69
        93
        92
79
                                        60
134
         65
Some additional sampling was performed at these plants;
the results, which are summarized in  Table 7, agree very
well with the long-term historical data shown in Table 6.
Table 7 also indicates the impact of total dissolved solids
and oil  on the  level of suspended  solids.  Data  from
exemplary plants are summarized below:
Exemplary Treatment
  Plants
                              COD     BOD    TOC
                             Removal Removal Removal
                             percent  percent   percent
        72
                                        87
                                                58
  There  is growing evidence that  high concentrations of
total  dissolved salts or  high  levels  of oils and  greases
entering  a biological plant  contribute to high TSS levels.
The  effect of  salts on  a  biological  treatment  system,
especially on an activated sludge process, are summarized1 in
Table 8.
                                                      66

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                                                         Table 6
                             Historic treatment plant performance 50% probability of occurrence
COD
Plant Treatment %
No. System4 Category Removal
I4 AL
2' 2 AS-AL
31 AS
41 AS
5' 2 TF-AS
6 AL
7 AL
8' AL
9i AS
10' AS
II12 AS-AL
12 AS
13 AS
14 AS
15 AL
16' AS
17' AS
18 AS
19' AS
20' AS
Exemplary Plant
Exemplary Single
Plants - Average
D
C
D
B
B
B-C
C
B
C
B
C
A-B
B
B

D
D
D
D
C
Average
Stage

75
96.4
63
64.2
73.5
74.5
.
85
.
_
.
.
67
25.4

-
74

69
BOD
TOC SS
Effluent % Effluent %
Mg/liter Removal Mg/liter Removal
320
470
200
120
83
165
75
80
-
97
610
.
226
.
1,760
1,520

296
378


97
93.5
83
90.1
99.7
-
.
73
-
82.5
.
63.6
97.6
98.8
93

92
10
16
15
291
9.9
23.5
152
20
20
59
294
410
63
362
.
303
157
46.9
82.2


60
.
97
-
-
42
-
-
.
.
-
-
79

60
Effluent % Effluent
Mg/liter Removal Mg/liter
170
.
100 -370
-
295
780
-
-
.
.
-
-
135

-
163
55
665
81
24.3
130
.
145
-
189
280
-
289
.
480
-
-
134

65'
Data Base
Duration Performance
(months) Period
6(Sept-Feb) daily average
12 daily average
12 monthly average
14 monthly average
14 monthly average
12 weekly average
12 monthly average
12 monthly average
7(Aug-Feb) daily average
12 weekly average
12 daily average
12 monthly average
14 monthly average
14 monthly average
6(July-Dec) weekly average
8(Aug-Mar) monthly average
6(June-Oct) daily average
12 weekly average
S(June-Sept) montly average
S(June-Sept) weekly average



1  Plants considered to be exemplary in performance.
2  Multiple-stage biological treatment
3  Plant 16 is not included in average
                                                         Table 7
                                               Treatment plant survey data1
                               COD
Total BOD
TOC
TSS
                                                                                                 TDS
  AS - activated sludge
  TF - trickling filter
                                                              Oil & Grease
Plant Treatment % Effluent % Effluent % Effluent %
No. System6 Category Removal Mg/liter Removal Mg/liter Removal Mg/liter Removal
22 AS-AL C 64 2,300 90
y AS D 71 284 73
42 AS B 57 214 82
52 TF-AS B 59 133 92
6 AL B-C 66 980 73
8J AL B 69 92 84
9 AS C 75 595 92
IP AS-AL C 94 337 99
13 AS B-C 65 940 90
I6Z AS D 54.8 1,650 82.1
172 AS D 60 1,400 81.4
77.3 1,000 90
18 AS D 22.1 2,680 16.7
192 AS D 59.5 5,100 69.8
202 AS C 96.2 317 99.5
21 AL C 62 600 78
22 AS B 16.1 1,370 47.5
23 AS B 95.4 147 92.6
Average5 72 87
1 Based on 24 hours composit samples.
2 Plants considered to be exemplary in performance
427
74
13
12
235
6
75
16
177
300
240
310
650
1,800
19
27
210
4!


32
71
35
43
11
26
69
27
64
80.8
63.4
76.8
-
55.8
96.6
66
8.3
95.4
58

based on historical
2,710
132
80
61
573
52
242
343
470
280
410
360
1,025
1,700
114
47
550
35


data.
Negative
Negative
40
97
Negative
99
Negative
Negative
120
43.6
Negative

42.9
Negative
Negative
89
53.4
Negative



Effluent
Mg/liter
4,700
62
14
44
362
3
50
145
338
552
1,300
732
1,170
2,500-
100
30
82
37



Effluent
Mg/liter
2,300
3,100
2,900
1,430
3,000
690
3,810
2,690
1,520
10,990
3,750
4,060
2,050
8,360
1,950
9,800
15,400
580



Effluent
Mg/liter
.
P
43
2-1
II-1
-
12'
P
63
226"
24"
22"
106"
-
)94
-
<.034
21"



3 Oil and grease are reported as carbon letrochloride extractables.
4 Oil and grease and reported as Freon extractables.
5 Includes exemplary plants as well as Plant 23.
* AL - aerated lagoon














                                                       67

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Granular Media Filtration
  The present use of granular media filters is very limited in
the organic chemicals industry. However, many industries
are in  the process of installing these niters in order to meet
effluent limits for TSS. The selection of media types and the
addition of chemicals can substantially influence the quality
of the final effluent, and it  is generally assumed that effluent
suspended  solids can  be  reduced to a range of 5 to 30
mg/ liter (50 to 90 percent removal) through the use of these
filters. Some samples collected from organic chemical plants
were  tested  for suspended solids removal. The  results,
shown  in  Table 9, indicate  that filtration removed  an
average of 20% COD, 17% BOD, and 20% TOC.

Activated Carbon  Adsorption
  Granular activated carbon technology  has been exten-
sively  studied  in  the  United  States for  several years.
Although it seems feasible on a small scale, many problems
develop in full-scale situations. For example, there are high
attrition losses of carbon due to mechanical grinding and
other materials handling problems. Moreover, precise and
dependable  methods of operating the regeneration  furnace
have yet to be developed. Another problem is that many low
molecular weight compounds are not amenable to adsorp-
tion on  activated  carbon. The  clogging  and substantial
increases in head loss across the carbon column, which are
caused by TSS of more than 50 mg/liter and by more than
10 mg/liter of oils and greases applied directly to carbon
beds, are also matters of concern.

Table 8
Effects  of total dissolved  inorganic solids on biological system
performance
Salt Concentration
                           Effects on Biological System
          500 - 2,500        Optimum Activity
        2,500 - 5,000        Slight Increase in Effluent
                             Suspended Solids

        5,000 - 8,000        Suspended Solids in  Effluent
                             Settleability Decreases Slightly

       8,000 - 12,000        Significant Effluent Suspended
                             Solids Settleability Poor

       12,000 - 15,000        High Concentrations of Effluent
                             Suspended Solids.  Difficult
                           to Operate Activated Sludge.
                             Effluent Soluble BOD
                             Increases Settleability Very Poor
       15,000               Severely Toxic
Table 9
Removal by

Filtration
(Performed on Biological Treatment
Plant
3
15
15
14
9
9
13
4
24
12
21
16
25
20
35
26
27
18
17
19
Average1
% COD
9
87
85
24
11
10
32
	
8
21
3
84.3
39.3
8.5
51.4
26.2
—
86.8
88.4
33.3
20


Plant Effluent)
% BOD
4
56
. 	
28
	
	
36
	
2
	
__
57.8
	
17.2
	
71.4
12.5
72.1
55.6
—
17



% TOC
3
78
82
14
5
17
8

20
7
8
75.9
39.4
33.0
27.7
41.2
25.0
90.6
91.6
66.0
20
1 Average does not include plants 15, 16, 17, 18, and 26, since these
plants have excessively high effluent TSS and would bias the results

  The results of a survey at  six  activated carbon plants
treating  raw organic chemical wastewaters are shown in
Table 10. Based on these data and on small-scale laboratory
studies,  the  average performance for activated  carbon
systems was determined to be as follows:
     Parameter
       COD
       BOD
       TOC
 Carbon Exhaustion
Rate Ib. Removed/Ib.
      Carbon
       0.41
       0.03
       0.06
Soluble Removal
      %
      69
      20
      87
VI. Effluent Limitations  From  the  Various
Technologies

  In  reviewing  the  above data, the federal government
arrived  at  percentage  removal factors  and  minimum
concentrations that could be achieved through the applica-
tion of  the technologies discussed above.  These levels are
summarized below.

BPCTCA Treatment Systems - 1977 Standard
  The following pollutant reduction factors are  considered
achievable with BPCTCA treatment  technology:
                                                            BOD'
                                                            COD
                                                            TSS
                                                            'Controlling Parameter
                                                            2Annual Average
                                                            'Monthly Average
                    Reduction Factors
                    Range   Average
                    83-99%    93%2
                  . 63_-96%    74%2
                  reduced to 65 mg/liter*
                     Best Achievable
                      Under Worst
                       Conditions
                       mg/liter1
                          20

                          30
                                                      68

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                                                           Table 10
                                         Activated carbon plants treating raw wastewaters
                             Removal Efficiencies •
                Hydraulic
                 Loading
   Flows-gpd     gpm/sq. ft.  Contact Time-minutes    Carbon Exhaustion Rate
       Plant    Pretreatment     Design    Present   Design  Present Design Present Design Present     Design        Isotherm
      28    Solids Removal and
            Equalization 9-hr.
            detention time     —        Polyol-11   100,000  55,000  5.6    3.0      22
                                    40   0.4 Ib. polyol
                                          Ib. carbon
      29    Equalization 150-
            day detention time  TOC-94   TOC-89     20,000   7,000  0.49   0.17    540   1,550   0.07 Ib. TOC   0.19 Ib. TOC
                                                                                            Ib. carbon      Ib. carbon
      30    Equalization, Neu-
            tralization and
            solids removal     Phenol-89 Phenol-94  750,000 500,000  4.6    3.1
      31    Equalization and
            Neutralization     —
                                       TOC-91
 30,000  20,000
      32    Equalization and
            Neutralization     Phenol-99.9Phenol-95   72,000  22,000  2.0    0.6    215
      33    Equalization, Neu-
            tralization and
            solids removal     Color-90
800,000   —    7.7
  60     104   .028 Ib. phenol
               Ib. carbon


 660     912        -


         75        —



  27    —    5.4 Ibs. color
               Ib. carbon
  Federal permits for BPCTC A have generally been granted
on the basis of a plant's achieving 93 percent removal of
BOD on an annual basis. This allows, under worst winter
conditions,  a monthly average of 2.1 times  the annual
average and  a  maximum daily discharge of 3.9 times the
annual average. Although this approach works well in many
cases,  in  others—for  example,  multi-product,  batch-
operated, and  campaign-scheduling  industries—it is not
satisfactory, and generalized approaches have not proven to
be successful.

BATEA Treatment Systems - 1983 Standard
  Based on previous performance data for multiple-stage
biological  treatment  plants, existing carbon treatment
plants, and laboratory carbon data, waste reduction factors
were formulated  by the federal government for BATEA as
follows:
Reduction
Applied to
BPCTCA
Effluent
Limitations
90%'
60%'
reduced to 15 mg/ liter2

Best Achievable
Under Worst
Conditions
mg/ liter2
10
50
10
     Parameter
       BOD
       COD
       TSS

 * Annual Average
 2 Monthly A verage

   The affected industries do not agree with the limitations,
 claiming that there is not yet enough known about carbon
 technology.
            BADTC Treatment Systems - New Sources
              Based merely on filtration test data, the federal govern-
            ment proposed  the  following  reductions  for  BADTC
            technology:
             Parameter
                BOD
                COD
                TSS
 Reduction Factors
Applied to BPCTCA
Effluent Limitations
       17%'
       20%'
reduced to 10 mg/liter2
  Best Achievable
Under Worst Conditions
     mg/liler2
        10

        10
            Annual Average
            2Monthly Average

           VII.  Summary

              Since all of the above recommendations were made by the
           federal government primarily on the basis of its own studies,
           many  questions still remain within the organic chemicals
           industry  regarding  final  effluent limitations.  Since  the
           industry cannot be standardized, it is unrealistic to attempt
           to establish guideline limitations that are applicable to every
           industrial plant within each subcategory. Because of this
           complexity, each permit is generally evaluated on a case-by-
           case basis using the guidelines as a starting point. One key
           factor not considered by any of the guideline studies is the
           incorporation  of effluent variability  into the permits. For
           the  organic chemicals  industry,  in  which  most of the
           biodegradable  materials  are  soluble,  many operational
           constraints  and environmental  conditions influence  the
           variability of the final effluent. For  example, during cold
           weather, the effluent will deteriorate  because the biological
           organisms  cannot perform as they  do in  warm weather.
           Therefore,  the permits must be based on worst conditions,
           i.e., worst winter situations anticipated during the life of the
                                                         69

-------
permit. This is a subject currently under discussion between
industry and the government. In addition, because small
industrial  plants do  not have the capability  to  reduce
waste-water flows on the same level as the larger plants, they
have been penalized more severely. Industrial plants that
are multi-product in  nature and  employ batch processes
have much higher variability in raw waste characteristics;
consequently,  their  treatment facilities  are  subject  to
varying wastestreams, which results in much more variable
effluents than  those of continuously operated  industries.
Finally, those  industries that  manufacture  products  as
orders come in are subject to campaign scheduling in order
to meet requests  from  their  customers; such  campaign
scheduling can cause significant variability in the quality of
the raw waste and therefore of the treated effluent.
   Because of the above considerations and the difficulties
encountered in attempting to secure workable yet controlla-
ble permits, many problems  have arisen with respect to the
organic chemicals  industry's  efforts  to  comply  with
pollution  abatement  goals.  There is  no doubt that the
technology will eventually develop to allow industry  to
construct economically feasible treatment systems that are
capable of upgrading the water quality in the United States
and of being monitored  satisfactorily by the government.

               Acknowledgements

   The  majority of the information contained in this paper
was taken  from the April, 1974, publication, "Development
Document for Effluent  Limitations Guidelines and New
Source Performance Standards for the MAJOR ORGAN-
IC PRODUCTS Segment  of  the  Organic  Chemicals
Manufacturing, Point Source Category," based  on  a study
conducted  by  Roy  F.  Weston  Company  for the U.S.
Environmental  Protection Agency. The purpose  of the
study was  "to establish  effluent  limitations  guidelines for
existing point source discharges and standards of perform-
ance and pretreatment standards for new sources."
   All of the tables  except  Table 8 were taken from the
above  referenced publication.
Biochemical  Treatment of

Highly  Concentrated

Wastewaters  from  Wool-

Scouring  Operations

Skirdov I.V.,  Shvetzov V.N.,
Morosova K.M., Gubina  L.A.

  The  problems  associated  with   highly  concentrated
wastewater treatment are becoming more noticeable today.
A typical example of a given type of wastewaters is a highly
concentrated  wastewater  generated  from  wool scouring
plants. The wastewaters contain substantial amounts of wool
grease, wool, various impurities, dissolved  organic and
inorganic matter. The concentration of suspended solids is
up to 20 g/1, organic concentration varies ranging from 10 to
35 g/1. COD and from 5,0 to 20 g/1 total BOD. At present
mechanical,  chemical,  physical-chemical  and biological
treatment  processes  are being used to treat wool scouring
operation  wastewaters.  In spite of a variety  of treatment
methods,  these  wastewaters  present  certain treatment
problems.  Chemical treatment process requires the use of
expensive  chemicals, careful control of the  process and
accurate dosing of reagents, resulting in large production of
waste sludge. At the same time the area for application of
anaerobic Biological treatment in digesters is broadening due
to ease  of operation, reduced production of sludge and
efficiency.  The BOD limit in treated effluent from digesters
varies ranging from 800 to 1000 mg/1,  therefore  effluent
requires final treatment. It should be noted that digestion
detention period of 20 days is needed to produce an effluent
with a total BOD of 8000 to 1000 mg/1. In practice, existing
digesters are designed with detention period of 8-10 days,
resulting in effluent with a total BOD of 1500 to 2000 mg/1,
then effluent should be treated  in  municipal biological
treatment plants (Fig 1, Scheme 1).
  However  in  most  cases the  treatment   capacity  of
municipal treatment plants doesn't meet existing standards
and  isn't  sufficient  to handle wool-scouring wastewaters
without additional dilution after pretreatment in digesters.
It makes us seek ways of final wastewater treatment prior to
their  discharge  into  municipal  sewerage system or  to
receiving waters.
  The institute VODGEO has carried out studies on the
feasibility of wool-scouring wastewaters treatment  in
digesters followed by  final  treatment  in  aeration tanks
without dilution as well as  complete biological treatment
under  aerobic  conditions.  Studies  were conducted  on
natural wastewaters generated from worsted factory where
they are  treated by using soap and  soda.
   Experiments  were  carried  out   on  laboratory  scale
continuous flow models of digesters and complete mixing
aeration tanks. The facilities performance was monitored by
analyses  of  COD  and  total BOD,  pH, volatile fat acids
concentrations, the N and  P content, concentration of
ether-soluble material, anaerobic and  aerobic activated
sludge concentrations, quantity and composition of gas
produced from digesters. In order to obtain the criterion for
adequate evaluation of digesters performance as well as for
quantitative  evaluation  of biodegradable  substrate  in
                                                     70

-------
digesters determinations of influent and effluent BOD from
digesters have been  conducted according to special proce-
dure.
  As digesters are  completely mixed biological  reactors.
oxidation   rate  is  determined  on  the  basis  of  effluent
substrate concentration. The relationships  between oxida-
tion capacity  of digester  and  specific  oxidation  rate and
effluent organic concentration  were found  experimentally;
oxidation capacity and specific oxidation rate increase with
decreasing  the degree of treatment. It has been found that
the effect of effluent organic concentration and volatile  fat
acid concentration on specific oxidation rate is expressed by
hyperbolic  function (Fig.  2)  and  may be described  by
Michaelis-Menten expression for fermentation reactions.
  r.ai BCD anaerobic
 ~T<  £ ViS ir. flour
     D     ~~fK>     I* Kn,  2°     35-
     £	-^ jgj  gg£00  ,'ggg /KM  '/jcc/jfCc'ialMLa fat aciJi    =j/l

Figure 2. Specific oxidation  rate versus organic concentration (on
BOD  basis) and  volatile fat acids concentration in effluent
I                                  to r.n:iicipal

                                  ;rfiatra'Mit  plant;";
                                       to nunicipol
                                        treatment planto;
                                                  to  receiving.
 Figure 1. Biological treatment schemes for wool-scouring operation
 wastewaten
 1. Primary settling tanks;
 2. Digestion tanks;
 3. Final setting tanks;
 4. - first-stage  aeration tank;
 5. - second-stage aeration tank;
                                                                             .





— ?



^




^



.








.




x'



X

'
"o«-/«r

^

mg BOD anaerobic
= 35.; g VSS in hour
r y,W> "s/i
LJ .
2 / r. "• .! 3 
-------
                   5 =  Vmax[S2]
                        Kmt[S2]

where:     ^  —  specific oxidation rate; mg BOD anaerobic per
                 g VSS in hour
          S2   -  substrate concentration, mg BOD anaerobic/1
                 or mg volatile fat acids 1/1.
        Vmax   -  maximum reaction rate, mg BOD anaer-
                 ob per  g  VSS  in hour.
         Km   -  Michaelis-Menten constant expressed as
                 substrate  concentration at which reaction
                 rate is equal to half the maximum rate.
  Method of binary reciprocal values was used  to define
Vmax and Km. It  can  be  seen from Fig. 3,  that maximum
specific  oxidation rate of  wool  scouring  wastewaters in
digesters is 33.3    Mg BOD     • h, km is 16700 mg/1.
                    gVSS
  As the value of constant Km is dependent on its nature
rather  than  substrate concentration, high  value  of Km
obtained for treated  effluent from digesters indicates the
complexity of wool-scouring wastewater composition.  The
effect of anaerobic activated sludge concentration on basic
technological  parameters  has  been  investigated for the
purpose  of improving digester  performance. Oxidation
capacity of digesters and  the degree of treatment considera-
bly increase with increasing activated sludge dosage while
specific  rate decreases. However it decreases slower than
increases activated sludge  concentration  due to  overall
oxidation rate increases.  The decrease in specific oxidation
rate with increasing sludge dosage appears to be accounted
for changes  in  prebacterial  film  under  hydrodynamic
conditions that in turn  prevents feeding  of substrate to
microorganisms and inhibits metabolism.
  In order  to define  the  relationship between anaerobic
activated sludge  concentration and specific oxidation rate
coefficient Ksiudge have been suggested.
  Coefficient Ksiudge is equal to the ratio of specific rate at a
given sludge concentration  to rate at sludge  concentration
of 5 g VSS/1.
  It has been  proven that coefficient Ksiudge doesn't depend
on  substrate concentration, but depends only on anaerobic
activated sludge concentration (Fig. 4).
  Taking into account specific  oxidation rate and coeffi-
cient Ksiudge technological parameters of digesters treating
highly  concentrated wastewaters should be  calculated by
using the equation:
       T=.


where: T
       So

       St

        5
   Ksiudge   =
                   So-St
                   detention period in digesters, days.
                   organic concentration in influent, mg/1
                   total BOD.
                   effluent  organic  concentration  mg/1
                   total BOD.
                   specific oxidation  rate at sludge con-
                   centration on VSS 5 g/1, mg total BOD
                   per g VSS.
                   ash content in sludge, parts/unity.
                   coefficient considering effect of sludge
                   concentration  on  its activity, deter-
                   mined experimentally.
                                                          The  studies on the final  treatment  of wool  scouring
                                                        wastewaters  have  shown  that  treated  effluent  from
                                                        digesters with unoxidized organic material content of 3000
                                                        mg/1 on  a total  BOD basis, can be treated  successfully
                                                        without dilution   in  complete  mixing  aeration  tanks,
                                                        operating according to a  two-stage scheme.
                                                          It is evident from Fig. 5 that oxidation kinetics of wool-
                                                        scouring wastewaters in complete mixing aeration tanks can
                                                        be described by Michaelis-Menten expressions for fermen-
                                                        tation kinetics.
                                                          The values of kinetic constants (Fig. 6,7) have been found
                                                        experimentally  and   may  be used  to  calculate  basic
                                                        technological  parameters  of aeration tank performance.
                                                          With reference  to Fig. 6, 7, it can be seen that maximum
                                                        specific oxidation rate in a first-stage  aeration tank is 55.5
                                                          mg BOD      hour and in a second-stage aeration tank is
                                                        g VSS hour
                                                                                        mgBOD
                                                                                         g VSS h
                                                          The value of constant Km for the first-stage aeration tank
                                                        is higher than that for the second-stage aeration tank and is
                                                        equal to 83.5 mg/1 and  13.8 mg/1, respectively. From data
                                                        obtained,  it can be concluded  that high oxidation rate
                                                        occurs  in the  first stage aeration tank because activated
                                                        sludge is under conditions of excess substrate. At the second
                                                        stage the required degree of treatment is  achieved at lower
                                                        oxidation rate due to lack of sufficient amount of substrate.
                                                        At each stage  in aeration tank the development of specific
                                                        microorganisms   takes  place  due  to  autoselection   of
                                                        microorganisms   acclimitized  to  given  conditions  and
                                                        mutant  changes in the  culture.  In its turn  it affects both
                                                        physical  properties of activated sludge (in  particular, its
                                                        settling  properties) and kinetics of biochemical treatment
                                                        process. In the first stage if amount of substrate isn't limited,
                                                        autoselection  of microorganisms  takes  place  promoting
                                                        increase  in  maximum oxidation rate, and  at  the  second
                                                        stage if amount  of substrate is limited the development of
                                                        the culture encourages reduction in K m value and more full
                                                        substrate utilization. So the division of the process into two
                                                        stages  improves  process efficiency at  the first stage and
                                                        provides more full oxidation of organic matter at the second
                                                        stage.
                                                                                                  wool-scouring waste
                                                                                                  water without pretreat-
                                                                                                  ment in digesters.
                                                                                                       wool-scouring waste-
                                                                                                       water treated in digester
Figure S. Relationship between specific oxidation rate in first-stage
and second-stage aeration tanks and effluent organic concentra-
tion.

-------
             9J
                          
-------
 eliminated, thus enhancing effectiveness and efficiency of
 the treatment process as a whole

    Table I. Technical-economic comparison of biological treatment
    schemes for wool-scouring operation wastewaters


Scheme

I
II
III
IV
V
Digestion
Treatment unit tank


15000
4000
-
4000
-
First-stage
aeration
tank
Volume (cu m)
_
1230
2700
1560
7700
Second-stage
aeration
tank

_
900
3560
1200
1200
Municipal
treatment
plants

3800
630
630
_
-

volume
(cu m)

18800
6760
6900
6760
8900
 Analytical  and  Process

 Improvements  in  Biological

 Treatment  of Municipal

 Waste Waters

 William J. Love

   The operation of biological wastewater treatment plants
 is a complicated process  requiring the blending of inter-
 disciplinary professions, skills and experience. To managers
 responsible for the  operation of wastewater  treatment
 programs, the biological treatment process appears to be an
 all too delicate, sensitive and often elusive process. Yet, the
 biological treatment process still remains today, sixty years
 after its innovation, as the most economical and widely used
 type of secondary treatment for large municipalities. This
 continued  popularity  has resulted  from the  biological
 process'  ability  to consistently  produce  good  quality
 effluents  when  properly  operated  and  controlled.  The
 emphasis here is  on  operation and  control; the key to
 successful  operation  of a biological treatment plant  is
 extensive analytical and  process  control. The  analytical
 investigations  must completely characterize all wastewater
 parameters and  also each step of the biological treatment
 process. The process control must incorporate the analytical
 results into an operational program based on the biological-
 chemical-physical principles of microorganisms metabolism
 and liquid-solids separation.  The  analytical and process
 control programs must be flexible to meet the ever changing
 conditions within  a  plant,  and  must be  continually
 reevaluated and  revised to meet the increasing growth of
 wastewater flows.
  The  intent  of  this  presentation   is  to  discuss  my
 organization's experience in operating biological treatment
 plants, to outline our analytical and process control
 programs, and to discuss the role of analytical and process
 control in solving some of the peculiar problems which have
 occurred  in our biological treatment plants.

Process Control Program

  A process control program in a biological treatment plant
involves  the  collection  and  analysis  of representative
samples of waste and  process flow throughout the plant;
 monitoring and controlling critical process functions and
 variables according to established principles; recording and
 evaluating historical  data for use in predicting trends and
 process modification requirements; and conducting experi-
 mental investigations with process modifications, and even
 with entirely new processes for solving treatment problems.
 Our own process control program can best be explained by
 example using one of our biological plants treating a high
 strength industrial waste.
   This plant is  a  10 MOD activated  sludge plant which
 treats a brewery waste having a 1000 mg/1 BOD concentra-
 tion and comprising 75% of the total influent plant loading.
 The plant has  screening, grit  removal, primary gravity
 clarification, large 13 hour detention complete mix aeration
 tanks, final gravity clarification with low surface loading
 rates of  360 gpd/square foot,  and  chlorine disinfection.
 Sludge handling  is  by  gravity  thickening, centrifugal
 dewatering and multiple hearth incineration. Although the
 plant's BOD removals have been excellent, the  activated
 sludge process produces a very light sludge floe which is
 difficult to separate in the final clarifiers and which results in
 the plant's not meeting expectations. A tremendous amount
 of analytical, process control and experimental work has
 been   performed  attempting  to  improve  the  settling
 characteristics of this activated sludge  system.
   Daily samples of the individual brewery, domestic and
 combined plant influent wastes are composited proportion-
 al to flow and analyzed for such parameters as TSS, SS,
 VSS, BOD, COD, TOC, TKN,  NHs-N, ortho PO
-------
control. This data is also used  to routinely prepare solids
balances around the activated sludge system for controlling
the return and waste activated  sludge flow rates from the
final clarifier and the overall sludge handling  requirements
of the plant.
  In addition to the  complex analytical work performed in
the laboratory,  the  plant operators periodically perform
simpler tests to closely monitor several critical functions in
the plant. These tests include conducting dissolved oxygen
profiles of the aeration tanks to insure that there is sufficient
oxygen present;  measuring oxygen uptake  rates  of the
activated  sludge biomass as  an  indicator  of changing
conditions such as influent shock loading or toxic wastes,
monitoring aeration  tank and return sludge concentrations
using laboratory centrifuges; performing settleometer tests
of  the  aeration  tank effluent  to  measure  the activated
sludge's settling characteristics;  and measuring the depth of
clear water  in the final clarifiers to the  sludge blanket to
indicate the overall  settleability and solids balance in the
system. All of the above tests are performed every two hours
to four hours and provide an accurate picture of existing
plant conditions. These  simple tests often serve as early
warning indicators of impending process upsets  and allow
the plant  personnel  to take corrective actions before the
final effluent deteriorates.
  This  plant has had  continued difficulty in producing a
satisfactoy settling activated sludge floe in spite of all the
close attention to monitoring and controlling the biological
process. Therefore, the plant's process control program was
expanded to try several process modifications. One of the
first was the addition of inorganic salts and organic poly-
electrolyites  to the  aeration tank  effluent in an attempt
to weight down the  sludge floe in the final clarifiers.  This
proved  to be not only far too expensive, but also not too
effective for this industrial waste. Alum addition  to the
primary clarifiers at a feed dosage of 100 mg/1 produced an
extremely clear primary effluent and  resulted  in overall
primary removals of 80% SS and 40% BOD, but there were
no  benefits  observed  in  the   activated sludge  system.
Chlorine and hydrogen  peroxide addition  to the return
activated  sludge  were tested for  controlling filamentous
microorganisms,  but this  proved  to  have no  beneficial
effect. The final clarifiers were modified with the addition of
mechanical  mixers and picketts to promote better floccula-
tion of the activated sludge floe, but this did not produce
better  settling. One of  the more  recent process control
modifications has been the conversion of the complete mix
aeration system to a plug flow aeration system in an attempt
to  influence the biological metabolism rate  and shift the
microorganism predominance away from the filamentous
and lower  microorganisms.  Consideration  is now  being
given to a further conversion of the aeration tanks so that a
sludge  reaeration  system  can  be evaluated.  Nutrient
addition in  the  form of nitrogen, phosphorous, and trace
metal supplements have been evaluated due to the industrial
waste's natural deficiency in  these substances, and  this
investigation  is continuing.  Each of the above process
modifications requires months  for conducting a complete
research investigation and full  scale plant trial. This work
requires considerable additional laboratory analytical work
and operational monitoring for a thorough  evaluation of
the testing program.
   In addition to the full scale  plant process modifications
discussed  above, our  process  control program  has also
included a considerable amount of pilot scale testing and
bench  scale experimental work.  Several  fong  term scale
model  pilot reactors have been operated to investigate all
aspects of aerobic  biological treatment  of this  brewery-
domestic waste. This pilot Work has investigated the effects
of aeration  detention time, biomass concentration, sludge
age, chemical  and nutrient additions, oxygen and mixing
intensities, pH adjustment and shock loading susceptibility.
Pilot work  was also performed  using ultra sonic sound
generation in an attempt to alter the activated  sludge floe
structure, causing it to degasify and thereby improving its
settleability. In this work, which showed no overall benefit,
lower frequencies tended to improve the initial settling rates
while  higher  frequencies  tended to mix the sludge and
completely  prevent  settling.  Several  solids  separation
processes have  been  piloted'  to be  used either as an
alternative or in conjunction with gravity clarification of the
activated  sludge. One of the processes piloted, floatation
separation,  proved  to  be a fairly  successful  method  of
activated  sludge  solids  separation but  proved  to be
unfeasible due to the large area requirements needed. Also,
this method  would  have required an  additional  solids
removal step  such  as microscreening to  meet the effluent
requirements.   Another  piloted  process,  mixed  media
filtration, was rejected because it required more backwash
water  than  the  total plant  influent. Still another piloted
process, dilution of the final clarifier influent mixed liquor
suspended solids by an  intermediary Sweco  centrifugal
solids  separator, has proven to  be both feasible and to
improve the settling characteristics of the diluted sludge in
the final clarifiers. The centrifugal solids separator appears
to  selectively  classify the  biological  solids so that  the
filamentous microorganism count in the  final  clarifiers is
reduced. Our process control investigations at this plant are
continuing with both full scale and  pilot testing.
  Another problem caused by septic sewage is that it does
not respond to treatment by the activated sludge process as
rapidly as fresh sewage. This condition required a major
deviation at our 24 MOD contact  stabilization  activated
sludge  plant  from  conventionally established  process
control for contact stabilization plants. The septic sewage at
this plant receives no primary clarification and  would turn
the influent ends of the contact aeration tanks black.  We
were unsuccessful in developing  a viable biomass in the
aeration system as long as we attempted to operate the plant
around conventional parameters of fifteen to forty-five
minutes detention  time  in the contact zone. Laboratory
pilot scale and full  plant testing indicated that a considera-
bly  longer contact  time  was  required   to  allow  the
microorganisms  to  assimilate  the septic waste.  The
treatment process was modified to provide  a minimum of
two hours detention time in the contact aeration tanks, and
immediately a viable biomass  developed. This resulted in
good treatment performance and a good effluent. Higher air
supply rates are required to maintain adequate  dissolved
oxygen  in  the contact  aeration   tanks,  and  a longer
proportion  of the  aeration system must  be  devoted to
contact aeration rather than stabilization aeration than was
originally designed.
   The second process control problem caused by our force
main system is that the plants experience a severe diurnal
flow pattern.  In a  force main system  flow  is immediately
                                                        75

-------
received  at  the  plant  when  outlying  pump stations are
operating. This eliminates  any flow lags  and dampening
such as are  experienced in gravity collection systems. We
receive very  high flows during the daytime and virtually no
flow at night, and the switch  from high flows to low flows
occurs rapidly within an hour as people go to bed and get
up. Using our 24  MGD  contact  stabilization plant as an
example, the present average daily flow is 16 MOD, but the
daytime flow rate from 6:00 A.M. to midnight is 20 MGD
and the nighttime flow rate from midnight to 6:00 A.M. is
only 4 MGD. Process control problems arise in trying to
maintain a  constant solids balance around  the aeration
system.  If the return sludge  flow rates are not carefully
adjusted to match the widely varying influent flow rates, the
solids concentration in  the  contact  aeration  tanks will
significantly  increase  during early morning—low flow
periods. Later, the high flow surges occurring at 6:00 A.M.
wash out the contact aeration tanks and exceed the solids
loading capacity of the final  clarifiers.  More  poundage of
solids are put into the final clarifiers in a short period of
time than can be  removed  by,  the  return  sludge flow,
resulting in  the  final clarifiers  filling up  with  solids and
dumping. Adjustment  of the final  clarifier return sludge
flow rates to compensate  for the varying  influent flows is
difficult due to the wide  variation in  the  liquid hydraulic
levels in the siphon suction  drawoff type final clarifiers.
Process control  to prevent solids dumping at this plant
requires  attention to clarifier sludge  blanket depths and
influent and return sludge flow rates. In order to expand the
usable capacity of the plant and to remedy some  of the
hydraulic variation effects, we are considering the installa-
tion of additional final clarifiers  to handle above average
daytime  flows and also  upstream  holding tanks to help
equalize the flow between daytime and nighttime.

Foaming

   A problem which recently  developed at one  of  our
activated  sludge  plants  is the production  of a heavy,
voluminous  foam in the aeration tanks. The  foam is dark
and  greasy and cannot be  dissipated with the usual spray
water.  The foam,  containing  considerable  solids, will
overflow the aeration tanks and literally spread across the
plant  site   if unchecked, causing nuisance  and  odor
conditions. The foam causes a thick greasy scum to form on
the final clarifier surfaces  which often spill over into the
effluent.  The  foaming material is  incorporated into the
mixed  liquor and lessens  its density, thus decreasing the
sludge's normal settleability.  The anaerobic digesters have
also experienced a severe foaming problem during this time.
It  was initially believed that  the foaming was due  to the
activated sludge system's sludge age, but exhaustive process
control  proved this not  to be so.    Attention was then
diverted to the possibility of influent synthetic detergents or
other industrial wastes, and  an extensive analytical waste
monitoring program was initiated to identify  the causative
agent and locate its source. The analytical tests included oil,
grease, ionic, nonionic, and cationic detergent determina-
tions for the plant flows and selected industrial contribu-
tors. After considerable research effort, we have concluded
that it is not a single factor  such as oil or grease causing the
foaming problem, J>ut more likely a combination of factors.
After several  exasperating months of having foam and
sludge moving around the plant grounds, we found a fairly
economical commercial  defoaming agent. This defoamer
reduces the foam level in the aeration tanks to an acceptable
level and prevents its overflowing. However, we've felt that
this is only treating the symptoms and  is not  a corrective
process  control  measure. Some interesting recent  outside
research  indicates  that  a  particular  foam  producing
bacteria, actinomycetes, may proliferate in activated sludge
systems  where there is no anaerobic digester  supernatant
returned to  the activated  sludge system. This  research
indicates that anaerobic digestors produce a  toxic  agent
which prevents actinomycetes growth and foam production
in  most plants.  As  a  possible coincidence,  we  had
discontinued returning anaerobic digestor supernatant to
the activated sludge system at this plant two months before
the foaming first occurred.  We  have now reinstituted a
program of limited  digestor  supernatant return to the
aeration system,  but  since the  plant's  own anaerobic
digestors are  themselves foaming, the test supernatant is
being trucked in from another plant.

Capacity  Upgrading

  The need arose at another of our activated sludge plants
to double the  existing treatment capacity before construc-
tion of  the  expansion facilities could be  completed.  The
original facility treating domestic wastewater had a 5 MGD
capacity  and utilized a conventional  plug flow activated
sludge system with both primary and final gravity clarifiers.
The plant was required to produce a 20 mg/1 SS and BOD
effluent.  Considerable bench and  full scale pilot work was
undertaken  to investigate alternatives  for increasing the
plant's capacity.  The method selected for increasing the
capacity  was to institute a process  modification and to exert
close  process control over the entire plant operation. The
aeration  system was changed  from the plug flow mode to a
contact-stabilization system.  Incidentally,  this   change
resulted with our having  an empty aeration tank left  over.
Alum and polyelectrolyte feed facilities were installed, and
alum  was added to the contact aeration  tank at a point
providing fifteen minutes detention in the tank.  The mixing
in the contact aeration tank provided excellent flocculation
with an alum  feed  dosage of only 25 mg/1., and a small,
densely  compacted activated  sludge-alum floe was pro-
duced. An organic polymer at a dosage of 1 mg/1 was added
to the contact aeration tank effluent at a manhole just prior
to its entering the final clarifiers. The flow's gentle roll in the
manhole and clarifier influent structures provided adequate
flocculation of the activated sludge-alum-polymer floe. The
result was a large dense  floe which rapidly settled in the
overloaded final  clarifiers, then being operated  at a  surface
loading rate of  1100  GPD/square foot. The  small alum
dosage used did  not create a measurable increase in sludge
production, and the overloaded anaerobic digestors were
able to  handle  the sludge  without any  adverse  effects.
Overall,  the process was  very  stable  and reliable  but
required  close control of the solids inventory as higher
solids levels tended to  be washed out by heavy rains. The
extra treatment  capacity was obtained with a relatively
small cost expenditure for the chemical feed equipment and
a low $ 170 per day increment of operating cost for alum and
polymer. The success  of the temporary  process control
technique has  led us to consider it for a permanent further
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expansion of this plant.

Force Main  System

  Most of our service area is extremely flat with elevations
ranging from only five to fifteen feet above sea level. The
majority of the wastewater flows are pumped long distances
from  outlying neighborhoods to our plants through force
mains. The distances  pumped through the  force  mains
approach  twenty miles and the detention time in the force
mains approach twenty-four   hours.  Such  a collection
system  as  this presents  two difficult process control
problems  in  the treatment  plants—a  highly septic  plant
influent sewage and a very marked  diurnal flow pattern.
  Sewage arrives at two of our activated sludge plants in a
very septic condition. The dissolved oxygen of the domestic
sewage is  zero, its hydrogen sulfide content approximately
10 to 12  mg/1,  and the color  is dark  black. This septic
sewage  causes  several  problems   with   the  biological
processes. First,  a severe odor problem is created within the
plant  and  extending to  adjacent neighborhoods  and
industrialized  areas.  This  rotten  egg odor is  highly
objectionable to the people working and living in the area.
Various methods have been tested to eliminate or reduce the
odor  levels.  One  of the  early attempts  was to  return
activated sludge to the plant headwords to freshen the raw
influent sewage.  Chlorination of the raw influent flow was
tested both at low and at massive dosage levels. Chlorina-
tion at  low dosages  of  20 to  30 mg/1 just  prior  to the
headworks was completely ineffective. Massive chlorination
of the septic sewage  was tested at  our 24 MGD contact
stabilization plant having no primary clarification. Chlorine
dosages of  50  to  60 mg/1 applied  approximately thirty
minutes upstream  of the plant proved to be effective  in
reducing the hydrogen sulfide and odor levels at the plant's
headworks.  However, the heavy chlorination tended  to
"sterilize" the influent wastewater, and chlorine residuals  of
1 to  2 mg/1 were carried  though the  plant's preliminary
treatment works and into the aeration system. This chlorine
residual carried  into  the aeration tanks knocked out the
contact stabilization activated sludge process and complete-
ly prevented an  active biomass from reforming during the
entire six month project. Although successful from an odor
control standpoint, the project  had to be discontinued. We
have also  tested air stripping, masking agents, nitrous oxide
and hydrogen peroxide as odor control measures. Of these,
only hydrogen peroxide has proven successful in reducing
odor  levels. Hydrogen peroxide is applied  at dosages of  IS
to  20 mg/1 at a  point  approximately  fifteen minutes
upstream  of the plant's headworks. The peroxide oxidizes
the sewage organics and the sewage has a bleached color
when it reaches the plant. Although the hydrogen peroxide
is effective, its daily operating  cost  of $700 per day is too
expensive and we are presently pursuing other methods. A
side benefit claimed for the hydrogen peroxide treatment is
that influent BOD levels are reduced by about 5%.

Sludge  Handling

  From the standpoint of our own experience, we  would
say that the single  most critical factor in process control  of
biological treatment systems is sludge handling. It is a futile
and disheartening experience  to  attempt  process control
over a biological process when its related sludge handling
facilities are either inoperative, inadequate or incompatable.
It is impossible to maintain process control over biological
systems where waste sludge cannot be effectively removed
when and in the  quantities required.  We  have  found
ourselves in severe problems  over the past few years when
the  construction of  our sludge  handling  facilities  was
delayed up to several  years behind the upgrading  and
expansion  of our sewage treatment plants.  Under these
situations,  we have  had to utilize innovative techniques to
stretch our existing sludge handling capabilities. Although
sludge handling  may  not  generally be  thought  of as a
biological process control measure, the overall operation of
a sludge handling system is indispensible to process control
of other biological treatment systems and therefore  merits
mention here.
  Most of our older plants utilize anaerobic  digestion for
sludge disposal.  In almost  every instance,  the  original
digestion facilities consisted of primary and secondary low
rate digestion. These systems became too overloaded to
function  properly  when  the  plant  flows  and   sludge
production  increased.  With  imminent  failure  of  the
anaerobic  digestors threatening to  upset the biological
processes,  the secondary  digestors  were  converted to
primary digestors,  and the sludge feed was  increased to
operate all digestors at higher rates. Digestor supernatant,
which was formerly separated in  the secondary digestors
and returned to the plant flow, was either piped or trucked
to  sludge holding  lagoons. This  modification  greatly
increased  the sludge digestion capacity of the  plants  and
allowed their continued successful operation. Due to land
limitations at one plant preventing construction of  sludge
lagoons, a solid bowl  scroll centrifuge was  installed to
dewater the combined primary digestor transfer sludge. The
cake was then landfilled in a much smaller area than would
have been  required  for the liquid sludge.
  Another activated sludge plant went on line four years
prior to the completion of its centrifugal dewatering/ incin-
eration sludge handling facilities. In the interim,  sludge
handling  was  accomplished by converting  two  spare
aeration tanks into aerobic digestors providing twenty days
detention. The unthickened aerobically digested sludge was
then pumped three  miles and applied to unused open farm
land. The  digested  sludge was spray irrigated for the  first
two years onto a planted grass cover crop. During  a later
project, the digested sludge was pumped through a 600 foot
flexible hose dragged by a  tractor  and  directly injected
beneath the  soil surface. The soil could  be walked over
immediately after injection and there was no surface runoff
from this system. The system's major advantages were its
lack  of  nuisance  conditions  and  its  soil enrichment
potential.

Pilot Studies

  Our organization has conducted  extensive  large scale
pilot work over  the past few years for purposes of either
prototype  design,  interim  plant upgrading,  or process
control. We  have tested a varied assortment of proposed
processes; we have either considerably altered or altogether
abandoned many of the projects.
   A four month  pilot study was undertaken of a proposed
lime clarification-biological  nitrification advanced  waste-
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water treatment process. This 100 gallon per minute pilot
unit utilized a high purity oxygen activated sludge system.
As a  result of the study, we concluded that the proposed
process would work and could produce the desired effluent,
but that the biological nitrification system was too sensitive
to pH and shock  loading caused by upsets  in  the lime
clarification system, and therefore the proposed system was
not practical from a process control  standpoint.
  Over a year's pilot work was performed on all types of
centrifugal dewatering devices  for all types of  sludges—
primary, waste activated, digested, alum and lime sludges.
The information gathered here  was used for the design of
six large centrifugal dewatering  facilities. A Porteous Heat
Treatment Process was piloted for three months to test its
dewatering capabilities on a high strength industrial waste
activated  sludge.  We  concluded  from  the  study  that
resolubilization of the sludge would create too high a return
loading on the activated sludge process and would further
complicate an already difficult  biological process control
problem. A Purifax Sludge Treatment Process was piloted
at several of our plants, and one unit was  installed for
handling excess undigested sludge. Also tested was a flash
dryer in which undigested sludge was quickly accelerated to
high speeds and completely dried within a few seconds. The
end product would be pelletized and used as fertilizer.

Personnel  Development

  One last item  directly  related to process control of
treatment  operations is personnel qualifications.  It is most
important to staff the wastewater treatment  plants with
personnel who understand and are fully qualified to control
the treatment  processes. We are operating sophisticated
treatment plants which are designed and operated based on
complex  biochemical  engineering  principles, and  it  is
unreasonable to expect untrained personnel  to  grasp the
complexities of these processes and successfully operate the
plants. Our organization is strongly emphasizing the need
and the requirement for operators to have secondary school
and   advanced  education.  We  promote  and  sponsor
operator's attendance  at training schools for wastewater
treatment plant operation, and we have conducted our own
school for  wastewater  operators  for several  years in
addition  to  the on-the-job training  given each  operator.
Also, it is just as necessary to maintain a competent staff of
trained engineeres, biologists and chemists to provide the
supervision and assistance required in the operation of these
complex treatment facilities.
Development  and

Improvement  of  the

Municipal  Sewage Biological

Treatment  Facilities.

Yershov   A.,   Kyghel   M.,  Zemlyak   M.,
candidates of sciences

  The paper describes aeration tank types of new designs
used  for municipal sewage biochemical treatment,  deve-
loped  by the Scientific Research Institute for Municipal
Economy. The paper provides  technological basis of this
equipment designing.
  A conclusion  of the necessity for choosing a certain
aeration tank depending on conditions and special features
of the sewage system is given.
  The achievements of chemical engineering are the ground
for modification of equipment arfd technology in the field of
biochemical sewage treatment, particularly, the activated  -
sludge process.
  There are three types of aeration tanks used in biological
oxidation of contaminations by activated-sludge process:
plug-flow, mixing tanks and combined systems.
  Of all these types the mixing tanks are every more wide
spread on a large scale that have been used lately only for
high concentrated  wastewater treatment. More profound
research  of kinetics and the pattern of sewage activated
sludge biological oxidation allowed  to modify this process,
in  particular,  the  methods of  rapid  removal  of low
concentrated  wastewater,  prevailing in suspended and
colloidal form.  The rapid  removal  process is  due to the
phenomena the kinetics of which is similar to adsorption
process kinetics that is why such  modification is called on
condition as "biosorption". In municipal sewage treatment
the rapid removal process in some cases is characterized by
zero  order  equations  that  is over the range  of low
concentrated  contaminations  the process rate does not
depend upon concentration; sewage retention  time in the
aeration tanks generally is determined by reactors type, that
is by the hydrodynamic conditions  in the aeration tank.
  Thus, municipal sewage with low concentrated impurities
(BOD up to 200 g/m3) can be treated in a complete mixing
system because under these conditions the activated sludge
biosorption capacity is used. Municipal sewage with an
average concentrated  impurities  (BOD from  250 to 350
g/m3) can be treated in  the  plug  flow reactors because
complete oxidation organic  matters process with active
mass  growth  must  take  place.  However,  taking  into
consideration that municipal sewage impurities are mainly
in  the form of small dispersed suspended solids colloid
matters, complete mixing aeration tanks or combined tanks
can be  used, under  economical  grounds  and  rational
installation design. High concentrated  municipal sewage
(BOD from 400 to 600-800  g/m3)  can be treated in the
multistage plants as activated sludge is adapted properly to
changed  load at  every step depending on concentration
changes of organic matters  during the process. On the other
hand the step sludge process gives the possibility to decrease
sludge growth and to increase general rate and degree of
process  proceeding.  Due  to  these  factors,  step-sludge
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process can be used for treatment of a low concentrated
municipal  sewage.  On account  of  these  conditions  the
various models of aeration tanks were designed: mixing
systems equipped with mechanical aerators and  different
modifications  of aeration tanks-clarifiers  with activated
sludge fluidized bed;  multistage  basins  with successive
compartments  or  fluidized beds  are  used as plug-flow
reactors.
  For treating the low concentrated municipal sewage the
main part of which consists of unevenly flowing biodegrable
industrial  wastes  contact  stabilization  aeration tanks
equipped with turbine  aerators were developed, (fig. 1).
  For average concentrated municipal sewage treatment
aeration tanks-clarifiers and settling tanks with sedimenta-
tion zone equipped with pneumatic and mechanical aerators
begin to be used together with conventional long-form plug
flow aeration tanks.  These facilities provide the impurities
removal (oxydation) and separation of sludge mixed liquor
in one and the same technological unit. The main advantage
of combined facilities  is simultaneous  usage of the whole
activated  sludge mass in sewage purification  process. In
view  of sludge  mixture  increased recirculation  between
aeration and clarification zones there it is set practically
uniform oxygenation regime and uniform activated sludge
load. The  above mentioned factors provide oxygenation
process practically through  the whole volume.
  As a variety of combined aeration  tanks with settling
zone aeroacclerators used for a low and average concentrat-
ed municipal sewage treatment with the capacity over the
range from 5000 to  50000 m3/d can be applied.
  Aeration tanks - clarifiers are rectangular basins divided
baffle plate into aeration and  clarification zones (fig. 2).
Raw wastewater is distributed into aeration zone where it is
mixed  with activated sludge,  and mixed  liquor  flows
through the openings into the degazation zones and then to
the clarification zones.
   Aeration tanks-clarifiers include contrary   to  aeration
settling tanks the system of baffle plates providing directed
circulation of mixed liquor as  a result of which downtake
flow  rate  increases in  clarification zones and  activated
sludge fluid-fluidized bed is formed. The presence of stable
fluidized bed is due  to the increased recirculation of mixed
liquor on  one hand,  and on the other hand  it  promotes
increased  recirculation that   is  intensification  of mass
exchange between aeration and clarification zones.
   In practice under the rational structural design these
factors permit to transfer the impurities oxydation process
to activated sludge fluidized bed that is to use it as a reactor.
Increasing process removal rate in fluidized bed is explained
by  intensity  of  mass  transfer  under nitration  mixing
condition. This stage  is proved by the experiments as it is
shown on the fig. 3.
   The curve 1 shows  the process in aeration tank-clarifier
with oxydation of impurities mainly in  fluidized bed (ratio
of  fluidized bed and  aeration zone volumns  is  4:1); the
curve 2 - depicts the process with partial transference  into
fluidized  bed (ratio of volumes is respectively 1:0,7); the
curve 3 characterizes  the process in aeration settling tanks
(Municipal Economy  Academy types, USSR) and "Degre-
mont" oxycontact, French  firm (the data are  approximat-
ed).
   Hydraulic  loading  on activated sludge fluidized  bed
depended  on  MLSS  concentration is the  main  factor
  limiting aeration tanks-clarifiers capacity.  This relation is
  shown  on the  fig.  4.  Optimum  sludge concentration is
  determined in its turn, by sewage impurities concentration
•  that  is  by organic matters  load  on  the facilities. For
  municipal  sewage the range of activated sludge concentra-
  tion in aeration tanks-clarifiers is within the limits of 2 - 5
  g/1 that corresponds to a hydraulic loading in values 1 - 2,5
  m3/m2  • h(0,3 - 0,7 mm/s).
    Two typesizes  aeration tanks-clarifiers  are design for
  municipal sewage treatment stations of the capacity 17000 -
  160000 m3/d.  Besides,  aeration tanks-clarifiers designing
  principle is a base of long-form aeration tanks intensifica-
  tion by means of their reconstruction into aeration tank-
  clarifiers. Although aeration zone volume is too high, there
  is  necessity  to use  secondary settling tanks and  total
  biological  treatment complex capacity  increases. There is
  also  some  possibility  of  increasing  activated  sludge
  operational concentration. The calculations for reconstruc-
  tion  of present long-form aeration  tanks into aeration
  tanks-clarifiers  at  the  municipal  sewage   station,  the
  Ukraine, have  given the following results:  according to
         11-32-74 total sewage retention time in aeration tanks
  and secondary settling  tanks accounts for  13  h. at the
  oxydation rate in aeration tanks equal to 22,6 mg BODs/g.
  of  sludge after the reconstruction sewage retention time in
  aeration tanks-clarifiers has  become  7,73  h at oxydation
  rate 25,2 mg BODs/g of sludge/h. The secondary settling
  tanks  can now be  used for intensification  of the  other
  aeration tanks.
    The  hydraulic  principle   of  aeration  tanks-clarifiers
  desining was  used to  developed various  technological
  modifications of small  and average plants equipped with
  mechanical aerators in  order  to form fluidized bed.
    Two compartment aeration settling tanks use step-sludge
  sewage treatment  process at a low oxydation rate securing
  sludge  stabilization (total oxydation process).
    Aeration zone  is  divided  into  successively  operating
  compartments. The first compartment (stage) accepts high
  loads levelling their changes, securing the concentration of a
  considerable part of impurities on the activated sludge floes.
  A certain part of MLSS from the first stage compartment
  with the flow that is equal to the sewage flow outlets into the
  second stage where organic matters and the sludge grown in
  the first stage are mineralized by the sludge adapted to a low
  oxydation rate. Clarification zone and the second stage
  compartment  have  common  inner   recirculating  flow
  creating activated sludge fluidized bed in this zone as in
  aeration tanks-clarifiers.
    The first stage of two compartment aeration settling tanks
  is equipped with cylindrical or impeller rotor aerators; the
  second stage is equipped with longitudinal  rotation axis
  cylindrical rotor aerators.
    Hydrodynamic  scheme of  the  combined  aeration unit
  with cylindrical rotor aerator is characterized  by flow lines
  on  one plane  and thus simplifying  its calculation and
  maintenance.
    The  further  development and modification of aeration
  tank-clarifiers  tends  to the  facilities  design  with spread
  activated  sludge  fluidized  bed surface  without volume
  increasing and  with intensified vortical circulation within
  the beds.  This provides high  hydraulic  capacity of the
  aeration tanks-clarifiers, decreases' sewage retention time
  and increases sewage treatment quality.
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  Together  with  combined  aeration  facilities CMAS-
aeration tanks with secondary settling  tanks are  widely
used; they are stable to load changes during the day. These
facilities are  used  at  small communities,  towns  and
municipal sewage treatment plants designed for the capacity
up  to  7000  m3/d  with  food industry wastes of  high
concentrated  impurities,  flowing  from the  enterprises
located  there. Radial type  aeration  basins  APT and
circulation oxydation  ditches  UOK. were  developed for
these purposes. Both facilities are equipped with mechanical
longitudinal rotation axis rotor aerators.
  APT is  a cylindrical  basin  (fig. 5) with concentrically
installed secondary settling tank. The ring space is used as
an aeration compartment equipped with rotor aerators.
  UOK.  is  a circular ditch  (aeration  tank)  with rotor
aerators; secondary settling tank  is situated apart from the
ditch (fig. 6). The secondary settling tank is of a vertical type
(fig.  7). It has intensified hydrodynamic scheme  permitting
to increase  considerably  its  capacity in comparison with
"orthodox" type.
  The calculations of the process rates  and other kinetic
parameters  for described new  aeration facilities are based
on the unified method of the USSR  BUILDING STAND-
ARDS and  regulations         H-32-74, however,  the
calculations have some peculiarities in any single case due to
facilities hydrodynamic characteristics.
  Practical  application of the facilities is secured with a set
of experimental and standard designs and unified aeration
equipment.

                    Legend to figure 1

Contact stabilization aeration tank.
1 - sewage inlet
2 - turbine aerators
3 - return sludge inlet from secondary settling tanks
4 - discharge lines
5 - outlet of mixed  liquor to secondary  settling tanks
6 - contact basin
7 - stabilization basin

                    Legend to Figure 2

Aeration tank - clarifier
1 - clarification zone
2 - gates
3 - aeration zone
4 - overflow  trough
5 • degazation  zone
6 - cap
7 - trough for treated  water collecting and discharging
8 - surplus sludge outlet
9 - opening
10 - aerators
11 - sewage inlet
12 - "tooth"
13 - baffle plate

                    Legend to figure 3

Isotherms of impurities  removal  in combined  aeration  facilities
(Explanations are given in  the text).

                    Legend to Figure 4

Activated sludge fluidized bed calculated hydraulic load dependan-
cy on its MLSS concentration.
                   Legend to Figure 5

Radial type aeration basin.
1 - aeration compartment
2 - secondary settling tank
3 - rotor aerators
4 - treated water outlet
5 - MLSS outlet to recirculating pump
6 - surplus sludge outlet
7 - return sludge inlet by means of recirculating pump

                   Legend to figure 6

Circulating oxydation ditch
1 - shelter
2 - UOK
3 - recirculating sludge pump
4 - secondary settling tank
5 - rotor aeration tanks

                   Legend to figure 7

UOK secondary vertical settling tank
I - sewage inlet
2 - distributing compartment
3 - Roatting matters outlet
4 - collecting funnel
5 - toothed weir
6 - baffle  plate
7 - distributing trough
8 - trough for treated water collecting and draining
9 - discharge pipe
10 -cylindrical baffle
11 - sludge outlet
Protocol

of the third Meeting of the USA and USSR delegations on
the  problem  of  Prevention of  Water  Pollution from
Industrial and Municipal Sources (Moscow, USSR, August
22 - September 5, 1976)
  In  accordance  with the  Memorandum  of the third
Meeting of Joint USA-USSR Commission on Cooperation
in the  field of Environmental Protection  (Washington,
October 1975) the USA and the USSR delegations Meeting
on  the  problems of Waste Water Treatment was held in
Moscow,  August 22 - September 5, 1976.
  The  Soviet  delegation  was  headed  by  Prof.  S.V.
Yakovlev,  Director of the  Scientific Research Institute
VODGEO, Honoured Scientist of the RSFSR.
  The American  delegation was led by Mr.  J.T. Rhett,
Deputy Assistant Administrator, Water Program  Opera-
tions, EPA.
  The list of participants is attached in Appendix  I.
  In the course of the Meeting the following was accomp-
lished:
   I. The   Symposium  "Intensification  of  Bio-Chemical
     Treatment of Waste Waters".
  2. The   accomplishments of  the  1976  Program  of
     cooperation were discussed.
  3. Coordination of the Working program for 1977 was
     agreed upon.
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1

  At the Symposium  15 reports were delivered: 8 reports
were delivered from the Soviet Side and 7 reports from the
American Side.
  The list of reports delivered is attached as Appendix II.
  Of particular interest were reports delivered by the Soviet
specialists on technical oxygen usage for industrial waste
water treatment  and  bio-chemical  treatment of  highly
concentrated waste waters as well as the reports delivered by
American specialists on combined physical-chemical and
bio-chemical treatment processes and on designing of bio-
chemical treatment systems with the use of oxygen.
  The delegations have agreed that each side will publish all
reports  in  the necessary  number of copies in its  own
language prior to February 1,  1977 and will distribute them
among interested organizations. The sides will exchange 10
copies each of the published Proceedings of the Symposi-
um.
  In the course of the Meeting the specialists discussed the
results of current researches carried out in accordance with
the Program of cooperation and exchanged scientific and
technical literature.
  The delegations determined and coordinated the program
of cooperation for 1977 (Appendix III).
  The sides  have agreed that  the Symposium "Physical-
Mechanical Waste Water Treatment Facilities" will be held
in the USA, April 3-17, 1977.
  The following has been agreed about the preparation of
the forthcoming Symposium:
  —each side will present 5-7 reports at the Symposium;
  —the sides will exchange the report titles by February 1,
    1977.
  —the texts of the  reports will be exchanged in Russian
    and in English  prior to  March 1, 1977.
  Organizational Work for  carrying  out the Symposium
"Recycling Water Supply Systems and Reuse of Treated
Effluents at Industrial Enterprises" to be held  in the USSR,
September 18 - October 2, 1977 will be considered in the
course of the delegation meeting in April  1977.
  In 1977  an exchange of specialists will be carried out:
  —of Soviet specialists in the USA on the problems of
    waste water treatment, and
  —of American specialists in the USSR on the problem of
    waste water treatment and reuse.
  The  detailed exchange  program will  be agreed five
months prior to the date of the participants' departure. This
exchange  will  be carried  out on the basis  of equal and
"receiving-side-pays" basis.
  In the course of this visit to the USSR the American
delegation visited industrial and  municipal  wastewater
treatment  plants in Ufa, Leningrad, Shekino, Baikalsk and
Tashkent,  and  a  number of scientific research and project
institutes in  Moscow, Leningrad and Tashkent.
  Both sides expressed their satisfaction that the Meeting
was conducted in an atmosphere of friendship and mutual
understanding thus contributing to the further development
and strengthening of cooperation in the field of environ-
mental protection.
  This protocol was signed on September 4, 1976 in two
copies, in  Russian  and English,  both texts  being equally
authentic.
From the Soviet Side

S.V. Yakovlev
Chief of Delegation
From the American Side

John T. Rhett
Chief of Delegation
Appendix  I

List of Participants from the Soviet Side

S. Yakovlev
Director, VNII VODGEO, Prof. Chairman of the USSR
Delegation

D. Slavolyubov
Chief of the Department, Glavpromstroyproekt.
GOSSTROY USSR

I. Skirdov
Head of the laboratory, VNII VODGEO cand. techn. sci.

V. Ponomarev
Head of the laboratory, VNII VODGEO cand. techn. sci.

P. Kandsas
Head of the laboratory, VNII VODGEO cand. techn. sci.

I. Myasnikov
Head of the Sector, VNII VODGEO cand. techn. sci.

V, Shvetzov
Head of the Sector, VNII VODGEO cand. techn. sci.

A. Nechaev
Senior  Researcher, VNII VODGEO cand. techn. sci.

M. Voronina
Senior  Engineer,  VNII VODGEO

N. Nelubina
Interpreter
GOSSTROY USSR


List of Participants  from  the

American  Side

J.  Rhett
Chairman of the US Delegation Deputy Assistant Adminis-
trator for Water Program Operations, EPA.

A. Paretti
Consultant, Water Program Operations.

A. Cywin
Senior   Science  Advisor,  Office  of Water & Hazardous
Materials.
                                                     81

-------
W. Lacy
Senior Engineering Advisor, Office of Research & Develop-
ment.
W. Rosenkranz
Director, Waste Management Div.
F. Sebastian
President, Waste Water Equipment Manufactures Associa-
tion.
F. Harper
General Superintendent, Orange County Sanitation Dis-
trict.
W. Love
General Superintendent
Hampton Roads Sanitation District.
B. Sumner
President, U.S. Council of Consulting Engineers.
A. Malyshev
Interpreter, Colorado College.
Appendix  II
Reports

of  reports presented  at the  USSR-USA  Symposium
"Intensification  of Bio-Chemical  Treatment of  Waste
Waters"
From the Soviet Side

  1. Yakovlev S.V., Skirdov I.V., Shvetzov V.N., Rogovs-
     kaya C.I. (VNII VODGEO) "Kinetics of Biochemical
     Oxidation".
  2. Skirdov  I.V.,  Shvetzov V.N.,  Bondarev A.A., Lurie
     B.I., Bereyskina I.G., Katkova S.E. (VNII VODGEO,
     Complex "ASOT" in Shekino) "Operation Experience
     of Oxytanks".
  3. Shvetzov V.N., Morosova  K.M., Gubina L.A. (VNII
     VODGEO) "Biochemical Treatment of  Wastewaters
                          from W001-Scouring Operations".
                        4. Yakovlev  S.V., Karjuhina T.A. (MISI) "Biological
                          Waste  Water Treatment in  the Presence of Steroid
                          Compounds".
                        5. Shifrin S.M., Mishookov  B.C., Ivanov G.V., Goloo-
                          bovskaya E.K. (LISI) "The Trends in Intensification in
                          Biochemical Treatment of High Density Wastewater".
                        6. Gerber V.Y. (Bash. Nil NP) "Facilities Improvement
                          for Biochemical Treatment of Petroleum  Refinery
                          Wastewaters".
                        7. Skirckyavichus  R.L. (The  Ministry of Municipal
                          Economy  of  the   Lithuanian  SSR)  "Studies  of
                          Artificial Aeration in the  Lithuanian SSR".
                        8. Yershov A., Kyghel M.,  Zemlyak  M. (NIKTI GH)
                          "Development and  Improvement of the Municipal
                          Sewage Biological Treatment Facilities".

                      From the American Side
                        1. A. Cywin (EPA) Enchancement of Biological  Waste
                          Water Treatment'by Chemical Addition in the  Petro-
                          chemical Industry.
                        2. W. Lacy (EPA) "Steel  Industry Waste Water  Treat-
                          ment Using Biological-Chemical Technology".
                        3. W. Rosenkranz (EPA)  "Biological  Methods for
                          Control of Nitrogen in  Municipal Waste Waters".
                        4. F. Sebastian (EPA) "Improvements for Pulp and
                          Paper and Municipal Treatment Processes".
                        5. F. Harper (EPA) "A  Comparison of Conventional
                          Activated Sludge Process and Pure Oxygen Activated
                          Sludge Process for a 75 MGD Secondary Treatment
                          Facility".
                        6. B. Sumner (EPA) "Report on  the State of the  Art of
                          Biological Waste Treatment in the Organic Chemical
                          Industry in the United States".
                        7. W. Love  (EPA) "Analytical and Process Improve-
                          ments in Municipal  Bio-Chemical Wastewater  Treat-
                          ment".
Appendix  III
Program
USA-USSR  Cooperation  of Working  Group  on  Prevention of Water  Pollution  from
Industrial and Municipal  Sources
No.             Title
 I.   Modernization of existing and de-
     velopment of new combined facili-
     ties with high efficiency for waste-
     water treatment, including hydrocy-
     clones, multistage settlers, Rotators,
     facilities with utilization of technical
     oxygen, investigation of usage of
     flocculants and coagulants.
   Form of Work
Joint development
of themes, scientific
information and spe-
cialists delegation
exchange.
       Responsible for
    from the      from the
    USSR         USA
VNII VODGEO   EPA
Gosstroy
USSR
Time        Expected Results
1978    Improvement of the efficiency
        of existing and development o
        new treatment facilities, reduc-
        tion of space for location, re-
        duction of reagents and cost
        price of waste water treatment
     Development of hydrocyclones and
     flotation facilities; schemes of usage
     of coagulants.
Symposium on
"Physical-Mechani-
cal Waste Water
Treatment Facilities"
(USA, Cincinnati,
April 3-17, 15 days,
8 specialists)
VNII VODGEO
                                                    82

-------
No.
 2.
 3.
             Title
Development of tubular and plate
settlers and facilities with utilization
of technical oxygen; schemes of
usage of flocculants.
Intensification of wastewater treat-
ment process in petrochemical,
chemical, petroleum refining, pulp
and paper industries, and metallur-
gical industry.

Intensification of wastewater treat-
ment process in petroleum refining
industries, and metallurgical indus-
try.

Intensification of wastewater treat-
ment process in petrochemical and
pulp and paper industries.


Development of highly efficient me-
thods and facilities for removal of
nutrients and treatment of municipal
wastewaters; usage of treated  efflu-
ents in recycling systems at indus-
trial enterprises.

 Development of methods and facili-
 ties for removal of nutrients and
 treatment of municipal wastewaters.

 Usage of treated effluent in recycling
 systems at industrial enterprises.
 4.   Treatment of wastewater sludges.
      Stabilization and dewatcring of was-
      tewater sludges.

      Technology and facilities for utiliza-
      tion and treatment of wastewater
      sludges.

  5.   Exchange of two Soviet specialists
      for 2 months in US on the problem
      of usage of technical oxygen at
      biological waste water treatment
      plants.
      Exchange of two American special-
      ists for 2 months in the USSR on
      the problems of wastewater treat-
      ment and reuse.
   Form of Work
Symposium on
theme: "Recycling
water supply systems
and reuse of treated
effluent at industrial
enterprises" (USSR,
Moscow, Septem-
ber 18-October 2,
1977, 15 days, 8 spe-
cialists).

Information and
delegation exchange
 Joint development
 of themes, informa-
 tion and delegation
 exchange
                                    Information and
                                    delegation exchange
                                     Study of research
                                     work of American
                                     'companies and or-
                                     ganizations, partici-
                                     pation in scientific
                                     studies.

                                     Acquaintance with
                                     research work of the
                                     Soviet organizations
                                     and institutes, par-
                                     ticipation in scientif-
                                     ic studies.
                                                                       Responsible for
                                                                   from the       from the
                                                                    ISSR
                    I:SA
                 EPA and
                 appropriate
                 industries
                                                                                               Time
VNI1 VODCEO
Gosstroy
USSR
                                                                VN1I VODGEO
                                                                                    EPA
                                                                                           1978
VNll VODGEO
Gosstroy
USSR
                                                                VNH VODGEO
                                                                                 EPA and
                                                                                 appropriate
                                                                                 industries


                                                                                    EPA
                                                        1977
                        VNll VODGEO
                        Gosstroy
                        USSR

                        VNII VODGEO
                                                                                  EPA and
                                                                                  appropriate
                                                                                  industries

                                                                                    EPA
                                 1977
                                                                             EPA and
                                                                             appropriate
                                                                             industries
                                                                                                        Expected Results
Increasing of wastewater treat-
ment efficiency of existing
treatment plants, introduction
of new treatment schemes,
maximum usage of treated  ef-
fluents in recirculation.
Development of new treatment
facilities for prevention of wa-
ter basin eutrofication and de-
velopment of new treatment
systems with maximum usage
of treated effluents in recycling
systems at industrial enter-
prises.
Reduction of cost price of
waste water sludge treatment,
increasing of treatment facili-
ties efficiency.
                        VNll VODGEO
                        Gosstroy
                        USSR
                                                                                    EPA
                             HI Quarter  Studying of the USA expe-
                             1977        rience in the field of waste
                                         water treatment.
                                                     Ill Quarter  Studying of the USSR expe-
                                                     1977        rience in the field of waste
                                                                water treatment.
 NOTE: Companies to be involved in carrying out  the joint activities on the American  Side will be named at the 4-th meeting of
   specialists, April 1977. in the USA.
                                                              83

-------
 Appendix IV
 Itinerary
 for the US-Delegation Stay in the USSR at the US-USSR
 Symposium" Intensification of Bio-Chemical Treatment of
 Waste Waters".
                    Sunday, August 22
 Flight CY-242       Arrival at the airport. Putting
 19:10               up at the hotel.
 9:00


 9:15


 9:45




 10:25




 11:05

 11:20-11:35

 11:35
 12:15



 12:55

 13:10

 14:10




 14:50



15:30

15:45
 Monday, August 23
 Discussion on the program for the
 US-Delegation stay in the USSR.

 Opening ceremonies of the
 symposium

 Yakovlev S.V., Skirdov I.V., Shvet-
 zov V.N., Rogovskaya C.I. (VN1I
 VODGEO), "Kinetics of Biochemi-
 cal Oxidation."

 Cywin A. (EPA) "Enhancement of
 Biological Waste Water Treatment
 by Chemical Addition in the Petro-
 chemical Industry."

 Discussion.

 Break.

 Shifrin S.M., Mishookov B.G.,
 Ivanov G.V., Goloobovskaya E.K.
 (LICI)" The Trends in Intensifica-
 tion in Biochemical Treatment of
 High Density Wastewater."

 Lacy W.J. (EPA) "Steel Industry
 Waste Water Treatment Using
 Biological-Chemical Technology."

 Discussion.

 Break.

 Gerber V.Y. (Bash. Nil NP) "Facili-
 ties Improvement for Biochemical
 Treatment of Petroleum Refinery
 Wastewaters".

 Rosenkranz  S. (EPA)" Biological
 Methods for Control of Nitrogen in
 Municipal Waste Waters."

 Discussion.

 Skirdov I.V., Shvetzov V.N., Bon-
darev A.A., Lurie B.I., Bereyskina
I.G., Katckova S.E. (VNII VOD-
GEO, SHekinsky Complex
"ASOT") "Operation Experience of
Oxytanks".
 16:25


 9:00



 9:40




 10:20

 10:35

 10:50
11:30
12:10

12:25-13:25

13:25




14:05
14:45

15:00
15:40
16:00
10:00
                                                        Flight N 341
                                                        14:55
 Discussion.

 Tuesday, August 24
 Sebastian P.P. (EPA) "Improve-
 ments for Pulp and Paper and Mu-
 nicipal Treatment Processes".

 Yakovlev S.V., Karjukhina T.A.
 (MISI) "Biological Waste Water
 Treatment in the Presence of Ste-
 roid Compounds.)

 Discussion.

 Break.

 Harper F. (EPA) "A Comparison of
 Conventional Activated Sludge Pro-
 cess and Pure Oxygen Activated
 Sludge Process for a 75 MOD Se-
 condary Treatment Facility".

 Skirckyavichus A.L. (The Ministry
 of Municipal Economy of the Li-
 thuanian SSR, KPI) "Studies of
 Artificial Aeration in the Lithuanian
 SSR;"

 Discussion.

 Break.

 Sumner B. (EPA) "Report on the
 State of the Art Biological Waste
 Treatment in the Organic Chemical
 Industry in the United States

 Shvetzov V.N., Morosova K.M.,
 Gubina L.A. (VNII VODGEO)
"Biochemical Treatment of
 Wastewaters from Wool-Scouring
Operations".

 Discussion.

 Love B(EPA) "Analytical and Pro-
cess Improvements in Municipal
Bio-Chemical Wastewater Treat-
ment."

Discussion.
Adjournment.

 Wednesday, August 25
Visit to the Scientific Research Insti-
tute of Municipal Water Supply and
Wastewater Treatment.

Leaving for Upha.
                                                        18:40               Arrival in Upha. Putting up
                                                        (16:40 Moscow time) at a hotel. Rest.
                                                   84

-------
10:00



Flight 340
20:05

20:00

23:55


8:25


11:00



z!5:00
23:55



8:25

12:00
Flight 121
19:59
8:05


10:00

14:00


17:00
Flight 3719
15:35.

20:05
Thursday, August 26
Acquaintance with Treatment Facil-
ities of Petroleum Refinery Plant in
Upha.

Leaving for Moscow.
Arrival in Moscow.

Leaving for Leningrad by train.

Friday, August 27
Arrival in Leningrad, putting up at
a hotel.

Visit to the Leningrad Department
of the Institute "Sojusvodocanalpro-
ject".

Acquaintance with Experimental
Pulp and Paper Complex in Kras-
nogorsk, VNPO BYMPROM.

Saturday, August 21
Sightseeing excursions around
Leningrad.

Sunday, August 29
Sightseeing excursions around
Leningrad.

Departure for Moscow by train
"Red Arrow"

Monday, August 30
Arrival in Moscow.

Visit to Shekino, visit to treatment
facilities of the Complex "ASOT.

Leaving for Irkutsk.
Tuesday, August 31
Arrival in Irkutsk, putting up at a
hotel.

Departure for Baikalsk by buses.

Visit to the treatment facilities of
Pulp and Paper Complex.

Leaving for Irkutsk by buses.

Wednesday, September 1
Leaving for Tashkent.
'Arrival in Tashkent, putting up at a
hotel.
10:00


15:00
Flight 5087
8:00

8:55
Flight 688
20:24

22:44
                                                          10:00

                                                          17:00
Thursday, September 2
Visit to the department of VNII
VODGEO.

Acquaintance with the Salar Aera-
tion Plant.

Friday, September 3
Leaving for Samarkand.
Arrival in Samarkand. Sightseeing
excursions around Samarkand.

Departure for Moscow.
Arrival in Moscow, putting up at a
hotel.

Saturday, September 4
Excursion to Archangelskoye.

Signing the protocol. Final Meeting.

Sunday, September 5
Departure.
                                                      as

-------
                   References

lerusalimskii, N.K., 1967, Academy  of  Science, USSR,
Series of Biology, No. 3,339.

Michaelis L., Menten M.L., 1913,  Biochem 7,49,333.

Monod  J. Annual Review of Microbiology, 1949, 3,371.

Hinshelwood, C.N., The Chemical Activities  of Bacteral
Cee. Clarendon Press. Oxford, 1946.

Harbert  D., 1961, Sonety  of Chemical  Ind. Monogr., N
12,25-5.

Dawning, A.Z., Wheatliand A.B., Paper Press to  Mid.
Pranch. of Inst. of Chem. Eng. 1960.

Benedek, P., 1967, VITUK1 Report,  N 20, Budapest.

Gyunter, L.I., Zaprudskiy, V.S., 1971, Collection Microbi-
ological Industry, No. 5.

Garrett, T.M., Sawejer, C.N., 1961, Ind. Waste Contr. Fed.
N 33, 800-816.

Eckenfelder, W.W.,  1966,  Ind. Water Poll. Contr.  New-
York, Toronto, London.

McGabe, B.I., Eckenfelder, W.W.,   1961, J.  Wat. Poll.
Contr.  Fed. 33,3,258.

Zhukov, A.I., Karelin Ya, A., Kolobanov, S.K., Yakovlev,
S.V., Sewerage System "Stroyizdat," Moscow, 1969.

Wuhrman, K.,  e.a. 1959, Schweiz, Ztschr. Hydrol., 20,284.

Yeilevich, M.A., Korovin, L.N., Shvytov, I.A., Inf. Biol II,
All  Union School on Mathematical  Modeling in Biology.
USSR  Academy of Science, Pushchino,  1975.

Repin,  V.N.,  Materials of the Scientific-Methodological
Conference of  Aspirante MISI. Collection of Works, No.
62, Third Edition, Moscow, 1969.

 Karelin, Ya. A., Zhukov, D.D., Rozanov, V.L., Research
on Waste-Water Treatment,  Collection of Works, MISI,
No. 66, Moscow,  1970.

Smith,  D.B., Sex. and Ind. Wastes, 24, 9 Sept., 1952.

Okun,  D.A., Lynn, W.R., Biol. Treatment of Sw. and Ind.
Was'es. I. Aerobic Oxidation. R.P.C. New-York, 1956.

 Bennet, G.F., Kempe, L.L., Chem. Geng. Poc. Symposium
Series,  1967, 63, N 78.

Joung,  H.L., J. Bacterial, 1969, 97,  N 3.

Goftlieb, S.F., J. Bacterial, 1969, 92, N 4.

 Okun,  D.A., Sewage Works Journal, 21, 1949.
McKinney, R.E., Pfeffer, S.T., Water and Sewage Works,
October, 1965.

Kariuskiy,  A.A., Laskov, Yu.M.,  1958, News of Higher
Institutes of Learning Construction and Architecture, 10.

Gilsderman, Yu.I.,  1969,  Mathematization  of  Biology,
Moscow, "Znaniya"

lyervsalimskiy, N.D., Neronova, N.M., 1965, DAN USSR
161, No. 6, 1437.

Vestali, D. 1972, Ferentative Catalyst,  Moscow, "MIR"

Muzchenko,  L.A.,  Gubin,  V.A.  Kautere,  V.M.,  1973,
Collection  of Mathematical Modeling of Microbiological
Processes, Pushchino on the Oka.
                                                      86

-------
Table I
   Operation data of counter-flow aeration tanks with air and oxygen supply and acetone as a substrate


Lest
Number
Oxygen Supply
1
2
3
4
5
6
7
8
9
10
11
12

Air Supply
1
2
3
4
5
6
7
8
9
10
11
12
13
14


MLVSS
g/l

2.81
3.01
3.27
3.83
3.41
2.46
331
4.10
2.9
3.29
2.5
3.6
mean:

2.6
2.95
3.0
3.1
3.4
3.47
3.1
5.73
5.81
6.57
2.75
2.92
3.21
3.05

D.O.
Concentration
mg/l

11
7.3
17
10
10
14
7.3
14
14
16.5
13
13.8
12.7

2.5
2.5
2.4
2.3
3.1
2.7
3.2
3.3
3.6
3.2
3.0
3.0
3.4
3.2

Wastewater
COD
Influent

3962
4906
4610
4264
4850
3468
4667
5781
4089
4638
3525
5076


1070
1280
1026
1345
1475
1505
1007
2508
2257
2851
1193
1898
2808
2318


mg OV1
Effluent

132
154
174
99
61
71
174
102
125
166
94
981


69
54
84
76
84
307
125
55
120
104
31
23
61
46
Organic
Matter
COD
m'/day

7544
9333
8692
8223
9417
6727
11023
9034
7795
8819
6768
9307
8558

2402
2452
3982
2538
2782
2486
1760
1920
4280
5502
2397
3731
5037
1502
Specific
Oxidation
Rate
mg COD
g/hour

111.6
129.1
110.2
87.0
114
114
141.6
91.6
111.6
111.6
112.5
107.9
111.9

38.5
31.6
42.5
34.1
34.1
28.0
23.0
38.4
30.0
34.8
34.8
40.3
65.4
61.2
                           mean:
                                           2.98
                                                                                               3400
                                                                                                                39.4
iiiiiimry J.
Substrates
,

Desig-
nation
on
ri.ure
2

Flhyl alcohol I
Propyl alcnhol 3. 5
Ihupropyl alcohol 6
Butyl alcohol 4
Propyonic aldehyde?
Prapionic acid 8
Propylen glycoj 9
Benfalcohol 10
Ben/aldehyde 1 1
Ken/oic acid 12
Pyrocatechol 12
Rciorcipol 1 3
Hydrouuinone
Acelone
heptanol
lactic acid
acetylfornic acid
onho-creiot
meta-creaol
pira-crciol
14
15
16
17
18




Molecu-
Chemical lar
I 4
t'HtOH 3204
ClHiCH 46.05
OH'OH 6009
(CH)ICHOH 6009
CJ MO 12
UP"
(CHiHCO 5808
CHKCHlBCHlOH 11621
CHiCHOH CO:H 9008
CHJCO COlH 8806
CHH*OH 10814
CHiCiHOH 108 14
CHJC.IH4OH 10814
organic
carhon
rug m|!
mailer
5
0,37
0,52
ait
059
0.65
062
0.48
048
0.78
O.H
0.69
0.65
0.65
0-65
062
0.72
0,39
041
0,77
077
0.77
Water
My
1 I
6

90
200
40
33
30
451
2290
59

09

245
235
194
ton
m«O
mg
substance
7
156
184
23-24
2.22
240
220
151
157
2.51
241
2.0
1,9
189
1 86
217
2,7
1.07
091
2.31
245
245
BOD
maO
mj
substance
8
102-12
1)8
162
1 54
1 60
120
1 19
1 20
204
21
1.67
146
1.5
015
1,68
1.8
0.93
064
1 78
184
1.84

Kaho
BOD
COD
9
68-80
75
70
69.0
660
65
79
76.5
81
87.5
13.5
78.5
79)
8
77.4

7003

75


Diffe-
rence
COD-BOD
10
036
046
072
08
08
10
032
0.35
047
0)1
033
0.43
039
043
049

0.27



Oxidation
specific
rale
mg BOH
g il hour
II
2>-54»
I6.6<
141-215
167
16.6k
M.5
221
24.3
)5-3»
26
293
163-157
160
8-10
59-1)8

496



V™,,
m»O;
g • hour
12
•30
670
200
17
260
7J
45
125
158
202
3937
57)
415






K.


mjBOD COD-BOD
1
13
167
15
143
160
3.9
29
16
IS*
9.6
314
2163
12.3
0.786






COD
14
026
025
032
0.33
0.57
0.45
0.21
024
0.19
0 14
023
019
062
0.23






15

0022
0055
0.007
0.038
0.106
0.040
0 101
0.143
0069







(> D h\
V.irhurg
Sludge mm
increase m^ %, . ho|1I
* *
Id 17

Oil II
0..12 7
OSS 8
0,25 10.
016 II
031 28
024 240
062 17
193 21
108 19







IXiA IIMA
my si h\
summers
IK
13 5
125
I6X
98
150
184
143
235
158







Ihc number ..1
mid.Hii'n t drs skiduo
14
.' .10"
3 1(1"
,t III' '
4 10"
5 10-
3 10"
1 10"
.1 10'
1 10"'
3 10'"
3 10"

5 10'"




                                                            87

-------