ROBERT A. TAFT WATER RESEARCH CENTER
                        REPORT NO. TWRC-3
             AN INVESTIGATION
 OF LIGHT-CATALYZED  CHLORINE  OXIDATION
    FOR TREATMENT OF WASTEWATER
     ADVANCED WASTE TREATMENT RESEARCH LABORATORY • III
     U.S. DEPARTMENT OF THE INTERIOR
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
            OHIO BASIN REGION
              Cincinnati, Ohio

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  AN INVESTIGATION OF LIGHT-CATALYZED CHLORINE
     OXIDATION FOR TREATMENT OF WASTEWATER
                       by
     Alfred F.  Meiners, Elizabeth A. Lawler,
     Mary E. Whitehead, and John I. Morrison
                       for

The Advanced Waste Treatment Research Laboratory
      Robert A. Taft Water Research Center
           This report is submitted in
           fulfillment of Contract No.
           14-12-72 between the Federal
           Water Pollution Control Ad-
           ministration and the Midwest
           Research Institute.
        U. S. Department of  the  Interior
 Federal Water Pollution Control Administration
                Cincinnati,  Ohio
                  December  1968

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                          FOREWORD
        In its assigned function as the Nation's principal
natural resource agency, the United States Department of  the
Interior bears a special obligation to ensure that our expend-
able resources are conserved, that renewable resources are
managed to produce optimum yields, and that all resources con-
tribute their full measure to the progress, prosperity, and
security of America -- now and in the future.

        This series of reports has been established  to present
the results of intramural and contract research carried out under
the guidance of the technical staff of the FWPCA's Robert A. Taft
Water Research Center for the purpose of developing  new or im-
proved wastewater treatment methods.  Included is work conducted
under cooperative and contractual agreements with Federal, state,
and local agencies, research institutions, and industrial organi-
zations.  The reports are published essentially as submitted by
the investigators.  The ideas and conclusions presented are,
therefore, those of the investigators and not necessarily those of
the FWPCA.

        Reports in this series will be distributed as supplies
permit.  Requests should be sent to the Office of Information, Ohio
Basin Region, Federal Water Pollution Control Administration, 4676
Columbia Parkway, Cincinnati, Ohio 45226.
                             ii

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                           TABLE OF CONTENTS


                                                                 Page Mo.

Abstract ...................  ป  ฐ  .......    v
Summary:  Wastewater Oxidation Studies - The Effects  o
  pH and Irradiation Time

Introduction . .........................     4

First Series of Wastewater Oxidation Experiments ........     5

Second Series of Wastevater Oxidation Experiments ........    18

  Reaction in the Dark .....................    20
  Reaction During Irradiation ..................    23
  Effect of Irradiation Alone ..................    26

Third Series of Wastewater Oxidation Experiments . .......    27

  Further Investigation of the Effect of pH ...........    31
  Effect of Chlorine  Concentration  ...............    32
  Effect of Nitrate Concentration ................    33
  Effect of Temperature ............... - .....    34

Ultraviolet-Catalyzed Chlorine Oxidation of
  High-Ammonia  Effluents  ....................    49

Reactions  of  Aqueous  Ammonia with Chlorine ...........    54

  Ammonia-Chloramine  Determinations.  .  . . ......... . .    57
  Effect  of Irradiation on the Ammonia-Chlorine Reaction ....
57
 Comparison of UV Radiation  Sources  ....  	   59

 Ultraviolet-Catalyzed  Chlorine Oxidation of Pure Compounds ...   67

 Investigation of the Effect of Ultraviolet Radiation, Plus Other
   Oxidizing Agent?	   77

 Process Costs	   80

   Commercially Available, Ultraviolet  Sources   	   81
   General Design Considerations   	   81

                                    iii

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                      TABLE OF CONTENTS (Concluded)

                                                                   Page  No.

  Transmission of UV Radiation by Wastewater	    85
  Cost of Lamps, Power and Structure	    85
  Total Process Costs	    8?

Experimental	•	    89

  Photochemical Reactor  	    89
  Ultraviolet Radiation Sources  .... 	    89
  Analytical Methods 	    92
  Sources of Wastewater	    92
  Laboratory-Scale,  Sewage-Treatment Apparatus 	    96
  Effluent Analyses   	    96
  General Procedure   	    96
  Effect of Ultraviolet Radiation on Chlorine Water  	    99
  First Series of Wastewater Oxidation Experiments 	    99
  Second Series of Effluent Oxidation Experiments  	   100
  Third Series of Effluent Oxidation Experiments 	   104
  Extent of Organic  Oxidation Produced by Chlorine in the Dark . .   108
  Extent of COD and  TOC Elimination Produced by Irradiation
    at pH 5	109
  Ultraviolet-Catalyzed Chlorine Oxidation of High-Ammonia
    Effluents	110
  Ultraviolet-Catalyzed Chlorine Oxidation of Ammonia	114
  Comparison of UV Radiation Sources 	   116
  UV-Catalyzed Chlorine Oxidation of Pure Compounds  	   117
  Investigation of the Effect of UV Radiation, Plus Other Oxidiz-
    ing Agents	117
  Ultraviolet Absorbance of Treated and Untreated Wastewater
    Samples	   118

References	121
                                    IV

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                                ABSTRACT
          A study was made of the effect of ultraviolet radiation on the
rate and extent of chlorine oxidation of organic material in highly nitrified
effluents from biological sewage treatment plants.   Ultraviolet radiation
will very significantly increase the rate of this reaction.   Also, the
extent of oxidation which can be achieved by chlorine combined with UV radia-
tion is usually much greater than that which can be achieved by chlorine
alone.

          The rate of the catalytic oxidation is dependent upon pH, and the
most rapid rate of oxidation and most efficient use of chlorine are obtained
at pH 5.  In seven different experiments performed at pH 5,  the average COD
decrease was 67% in 5 min., 79fa in 10 min. and 95% in 15 min.

          The rate of organic oxidation is not proportional to the chlorine
concentration; however, the rate of chlorine consumption is.  Large ex-
cesses of chlorine do not increase the reaction rate but simply increase
the amount of chlorine required to eliminate a given amount of organic mat-
ter.

          The rate and extent of the catalytic organic oxidation at pH 5
are not  significantly affected by temperature.  However, both the rate and
extent of catalytic oxidation are substantially reduced by the presence of
ammonia  in an effluent.

          A  brief investigation of the scope of the UV-catalyzed chlorine
oxidation indicated that phenol, 2,4-dinitrophenol, glycine, formic acid,
and o-dinitrobenzene are oxidized rapidly and extensively.

          On the basis of organic oxidation rate produced per watt of UV
output,  high-pressure mercury arcs are about 2.7 times more efficient than
low-pressure mercury arcs.

          Process costs of 7.2^ to 11.1^/1000 gal. were estimated, based
on  several types of commercially available lamps.
                                     v

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                                 SUMMARY
              WASTEWATER OXIDATION STUDIES - THE EFFECTS OF
                        pH AMD IRRADIATION TIME
          Ultraviolet radiation will very significantly increase the rate
at which chlorine will oxidize the organic material in highly nitrified
wastewater.  Also, the extent of oxidation which can be achieved by chlorine
and UV radiation is usually much greater than that which can be achieved by
chlorine alone; 5 to 8 times more TOG and COD could be eliminated in 10 min.
by chlorine plus UV radiation than could be eliminated in 6 days by chlorine
in the dark.

          The rate of the catalytic organic oxidation is dependent upon
pH, and the most rapid rate of oxidation and most efficient use of chlorine
are obtained at pH 5.  The rate of organic oxidation at pH 6.5 is not as
fast as at pH 5, but is faster than at pH 8.5.  The organic oxidation rate
is much slower at pH 3 and at pH 10.

          Ultraviolet radiation alone will produce reduction in the COD
and TOC of an effluent; however, UV radiation plus chlorine is 3 to 10
times faster, depending upon pH; at pH 5, COD is eliminated more than 8
times faster, and TOC is eliminated 4.5 times faster.

           The wastewaters examined contained variable quantities of readily
oxidizable organic material.  The chemical oxygen demand  (COD) which could
be eliminated within 10 min. by chlorine  in the dark averaged 12%  (range
0.8-20$).  The  extent of total organic carbon (TOC) elimination during
this time  averaged 6$ (range  0-15$).-

           The oxidations of four different effluents were investigated at
pH 5.   In  seven  different experiments, the average COD decrease was 67$ in
5 min.  (range 51-84$), 79$ in 10 min. (range 66-100$), and 95$ in  15 min.
 (range  88-100$).  The average TOC decrease was 33$ in 5 min.  (range 15-50$),
52$ in  10  min.  (range 44-60$), and 75$ in 15 min.  (range  70-81$).

           The rate of COD elimination at  pH 5 is most rapid during the first
5 min.  and decreases as the oxidation proceeds.  The rate of TOC elimina-
tion, however,  is nearly linear over a 15-min. period.
                                     1

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Effect of Chlorine Concentration

          The rate of COD and TOC elimination is not proportional to the
chlorine concentration; however, the rate of chlorine consumption is.   Large
excesses of chlorine do not increase the reaction rate but simply increase
the amount of chlorine required to eliminate a given amount of organic
matter.  Most efficient use of chlorine is obtained when the chlorine is
added gradually during the irradiation period.
Effect of Temperature

          The rate and extent of the catalytic organic oxidation at pH 5
are not  significantly affected by temperature.  The rate of COD elimination
at 25ฐC  (77ฐF) is only slightly greater than it is at 5ฐC (41ฐF).  The
rates of TOC elimination are about the same at both temperatures.
 Effect  of Ammonia

           The presence of ammonia in an effluent drastically reduces the
 rate and  extent of the UV-catalyzed chlorine oxidation of organic matter.
 For example, the addition of  23 ppm of ammonia nitrogen to a highly nitrified
 effluent  reduces the organic  oxidation rate by more than tenfold.  The
 amount  of chlorine actually required to eliminate 1 ppm of ammonia is about
 four times the theoretical amount required to eliminate 1 ppm of COD.  Also,
 the oxidation of organic matter is greatly inhibited until all the ammonia
 is oxidized.

           In water, ammonia reacts with chlorine to form mono-, di- and
 trichloramine in various proportions, depending upon pH and ratio of reactants,
 At pH 5,  an excess of chlorine rapidly converts most of the ammonia to
 trichloramine which is relatively stable in the presence of excess chlorine.
 Irradiation of an ammonia-chlorine reaction-mixture rapidly accelerates the
 conversion of trichloramine to nitrate and other oxidation products of
 ammonia including, presumably, nitrogen gas.
Oxidation of Pure Compounds

          A brief investigation was made of the effect of UV-catalyzed
chlorine oxidation on the TOC of water containing eight pure organic com-
pounds.  The following compounds'are oxidized rapidly and extensively:
phenol  (61$, 8 min.), 2,4-dinitrophenol (55%, 10 min.), glycine (61$, 4 min.),
formic  acid (90$, 4 min.)? and o-dinitrobenzene (65$, 10 min.).  Benzoic

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acid is also oxidized (45%, 10 min.), t>u"t no~t as fast as the other compounds.
Acetic acid and ethanol are oxidized at a much slower rate (less than 10%,
10 min.).
Other Oxidizing Agents

          A very brief study was made of the extent of organic oxidation
produced when wastewater was treated with UV radiation plus (l) molecular
oxygen and (2) hydrogen peroxide.  No significant decrease in TOG was
detected after oxygen had been bubbled through an irradiated reaction
mixture for 20 min.  Hydrogen peroxide produced no significant decrease
in TOG after 30 minป in the dark; irradiation of this reaction mixture for
another 30 min. produced only a slight decrease in TOC.
Ultraviolet Sources

          At  the present time, mercury-arc lamps are probably the most prac-
tical  sources of UV  radiation for the catalytic chlorine oxidation of organic
material  in wastewater.  On  the basis of organic oxidation rate produced
per watt  of UV output, high-pressure mercury arcs, which emit a broad spec-
trum of wavelengths  (220 - 366 mp,), are about 2.7 times more efficient than
low-pressure  mercury arcs which emit almost exclusively at one wavelength
 (253.7 mj, ).
Process  Costs

           Process  cost  estimates were made  for  large-scale application of
UV-catalyzed chlorine oxidation to wastewater.   Costs of 7.20 to 11.10/1000
gal.  were  estimated  employing  commercially  available UV lamps.  The assump-
tions made were  that a  contact time of  10 min.  is required for effective
organic  oxidation  and that the catalytic process requires the application
of 15 times more radiant  energy than that required  for UV sterilization.

           Process  costs could be lowered substantially if any one of the
following  factors  could be reduced:  (l) the amount of radiant energy per
unit  volume required for  effective oxidation, (2) the contact time and
(3) the  cost of  the  radiation  source.   The  precise  determination of these
factors  will require a  study designed to determine  exactly how much waste-
water can  be treated effectively using  each radiant energy source.

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                              INTRODUCTION
          Earlier studies at Midwest Research Institute had demonstrated
that ultraviolet radiation strongly accelerates the rate at which aqueous
chlorine oxidizes starch and other organic compounds .-2—1  Chlorine is
widely used for the disinfection of water.  However, in the absence of
ultraviolet radiation, chlorine will oxidize only a small fraction of the
                               *Z A I
organic material in wastewater. ?.,,/

          The purpose of the present work was to determine the usefulness
of ultraviolet-catalyzed chlorine  oxidation in producing more extensive, and
more rapid,  removal of the organic material in  highly  nitrified wastewater.
Another objective was to estimate  the cost of large-scale application of this
process.  The results of this  research are presented in nine major sections.

          The first  series of wastewater oxidation experiments was a gen-
eral investigation of the  effect of pH,  and a comparison of the rate and
extent of organic oxidation which  could be achieved by chlorine plus UV
radiation, by chlorine alone,  and  by UV radiation alone.

          The second series of wastewater oxidation experiments was designed
to determine the effect of variation in the amount of chlorine applied,
variation in irradiation time, and the effect of relatively small differences
in pH.

          The third  series of  wastewater oxidation experiments was designed
to. clarify further the effects of  pH and chlorine concentration, and to
determine whether or not the catalytic oxidation was subject to a tempera-
ture effect.

          The fourth section discusses the problems which arise if relatively
large amounts of ammonia  (15-30 ppm) are present in the effluent.

          The fifth  section discusses the results of a direct investigation
of the ammonia-chlorine reaction.

          The relative  effectiveness of two major types of UV sources is
discussed in a sixth section.

          The various  factors  which influence the cost of large-scale
application of this  process are discussed in a  seventh section.

          The eighth section describes briefly  the application of
UV-catalyzed chlorine  oxidation to pure organic compounds.

          The final  section discusses the effect of W radiation on the
oxidizing action of  oxygen and hydrogen peroxide.

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           FIRST  SERIES  OF WASTEWATER OXIDATION  EXPERIMENTS
                                 Summary
          Experiments in this series showed that the oxidation of organic
matter in wastewater by chlorine is much faster when the reaction mixture
is irradiated than when the reaction mixture is kept in the dark.  The
extent of COD elimination in the catalytic process is always greater than
the extent of TOG elimination.

          Chlorine plus UV radiation produces organic oxidation 3 to 10
times faster than UV radiation alone, depending upon pH.

          Considerable portions of  ammonia in wastewater are converted
to nitrate by the UV-catalyzed  chlorine oxidation process.

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First Series of Wastewater Oxidation Experiments

          The first series of experiments was designed to compare (l) the
effects of two pH levels  (pH 5 and pH 10),  (2) the difference between
reaction in the dark and  reaction when irradiated, and (3) the difference
between radiation alone and radiation plus  chlorine.  The design of this
series of experiments is  shown in Table I.
                                 TABLE I

                          EXPERIMENTAL DESIGN,
                        FIRST SERIES  OF EXPERIMENTS

                                                       Experiment Number
                                                     pH 5           pH 10

 Chlorine,  plus  irradiation                            3               4
 Irradiation,  no chlorine                             5               6
 Chlorine,  no  irradiation                             7               8
           The pH levels of 5 and 10 were  chosen because, at pH 5, the active
 chlorine in solution is 100$ hypochlorous acid; while, at pH 10, the active
 chlorine is 100$ hypochlorite^/ (Figure l).*  These two reagents would be
 expected to react differently in the catalyzed oxidation because of their
 distinctly different ultraviolet spectra  (Figure 2).

           The procedures used in this series were slightly different from
 those used subsequently.  The effluent in this series was acidified at
 the point of collection (4 ml. H2S04/gal), and the pH was adjusted prior
 to each experiment using 40$ sodium hydroxide.  In  subsequent experiments,
 acidification at the point of collection  was omitted.  Also, contrary
 to subsequent procedures, the UV lamp in  this series was not allowed to
 reach maximum irradiation intensity before being inserted into the reactor.

           The analytical results obtained for chlorine concentration, COD
 and TOC (which are presented in Figures 3-8) are summarized in Tables II
 and III.

           The first conclusion derived from this series of exploratory ex-
 periments is that the oxidation proceeds  many times faster upon  irradia-
 tion than it does in the dark.  Thus, the indicated rate of oxidation
 at pH 5, as measured by the rate of TOC elimination and the rate of chlorine
 consumption, is 60 to 100 times faster upon irradiation than it  is in the dark.
    Figures in this  report  are inserted at  the  end of the section to which
      they apply.

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                                 TABLE II
               RATES OF DECREASE IN CHLORINE CONCENTRATION,
TOC AND COD IN FIRST SERIES OF EXPERIMENTS
Average Rate Average Rate
Reaction Conditions
Exp.
No.
3
4
5
6
7

8

Initial Cl2
Concn. (ppm)
150
150
0
0
150

150


pH
5
10
5
10
5

10

Types of
Irrad.
UV
UV
UV
UV
None

None

of Decrease in
Chlorine Concn.
(ppm/min)
8.82
6-22V
--
—
0.133k/
0.055^7
0=290^/
0.0177k/
of TOC
Decrease
(ppm/min)
0.237
0.22
0.051
0.073
0.0037
__
0.016
0.00066
                                                               Average  Rate
                                                                  of COD
                                                                 Decrease
                                                                 (ppm/min)

                                                                  1.08
                                                                  1.10
                                                                  0.132
                                                                  0.110

                                                                  0.012

                                                                  0.00033
a/ In this experiment the chlorine disappearance was very rapid, so that
     this value could only be estimated.
p_/ In Experiments 7 and 8, the chlorine concentration apparently decreased
     at a non-linear rate (see Figures 7 and 8) until it reached a certain
     level (about 65 ppm); then it remained constant.  The first values refer
     to rates during the first few hours of the experiment.  The second
     values were calculated for the duration of the entire experiment
     (1,340 min. for Experiment 7; 4,535 min. for Experiment 8).
                                 TABLE III
                     EXTENT OF COD AND TOC DECREASE IN
FIRST SERIES
OF EXPERIMENTS


Reaction Conditions
Exp.
No.
3
4
5
6
7
8
Initial Cl2
Concn. (ppm)
150
150
0
0
150
150

pH
5
10
5
10
5
10
Types of
Irrad .
UV
UV
UV
UV
None
None
COD
(V
95
82
82
59
51
16
Decrease
(min.Ji/
27
20
170
145
1,341
4,535
TOC
ill
55
25
73
84
12
15
Decrease
(min.);
27
20
170
145
1,341
4,353
a/  Irradiation time or reaction time depending on the nature of
      the experiment.

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          However, these differences in reaction rates are somewhat exag-
gerated because the rate of  oxidation in the dark is most rapid at the
beginning of the oxidation;  and,  in these  experiments, the oxidation in
the dark was essentially complete long before the final COD and TOC samples
were taken.  The gradual slowing  of the oxidation rate in the dark is indi-
cated  from the plot of  chlorine consumption vs. time in Experiment 7
(Figure 7).  Subsequent studies (see.the later section entitled "Second
Series of Experiments") have shown that there is wide variation in the
amount of organic material which  can be oxidized in 10 min. in the dark.
However, when irradiation  is begun after 10 min. in the dark, the rate of
organic oxidation is  increased up to 15-fold.

          The second  general conclusion drawn from this series of experi-
ments  was that the extent  of COD  elimination is significantly greater than
the extent of TOC elimination.  This conclusion was shown to be valid for
all subsequent experiments.

          In the initial series of experiments, there appeared to be little
difference between pH 5 and  pH 10 in respect to the rate of TOC and COD
elimination.  However,  this  similarity was the result of inopportune sam-
pling  times  (see Figures 3 and 4),  and subsequent experiments indicated that
the rate of organic oxidation is  considerably greater at pH 5 than at pH 10.

          A third conclusion from this series of experiments was that chlo-
rine plus UV radiation  produces more rapid decreases in TOC and COD than UV
radiation alone.  Comparing  rates produced by chlorine plus UV radiation
at pH  5 with rates produced  by UV radiation alone at pH 5,  COD is eliminated
8.2 times faster, and TOC  is eliminated 4.5 times faster; at pH 10, COD is
eliminated 10 times faster, and TOC  is eliminated 3 times faster.  Subsequent
experiments (see "Second Series of Experiments", p.  18) indicated that, at
pH 6.5, chlorine plus UV radiation eliminates COD about 7 times faster than
radiation alone.

          The effluent  used  in this first series contained considerable
amounts of ammonia (2-6 ppm  N) .   'Some difficulties in precision were encount-
ered in these ammonia determinations because of turbidity,  which was prob-
ably the result of required  adjustments in pH.  Ammonia concentrations
determined for the first series of experiments are shown in Table IV.   In
every experiment in which  chlorine was present, there were  very significant
decreases in ammonia concentration.  (The ammonia-chlorine  reaction is
examined in greater detail in the section concerning the oxidation of high-
ammonia effluents, p.  49, and the  section concerning the ammonia-chlorine
reaction, p.  54).

          Ultraviolet radiation alone (Experiments 5 and 6) had almost no
effect on ammonia concentration.   This conclusion was verified in a sub-
sequent experiment  (Experiment 15, p. 115).

                                    a

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                                TABLE  IV
                         AMMONIA CONCENTRATIONS
                       (First  Series  of  Experiments)
           Reaction Conditions
Exp.
No.
3
4
5
6
7
8
Initial C12 Types of
Concn. (ppm) pH Irrad.
150
150
0
0
150
150
5
10
5
10
5
10
uv
uv
uv
uv
None
None
                                                          Ammonia (ppm li)
                                     Reaction Time
                                         (min.)

                                           27
                                           20
                                          171
                                          145
                                        1,341
                                           01           R ^b/
                                           ri-L           —> • ซJ—I
                                        4,535
a/ These gTmnon-ia values were obtained using a relatively fresh sample of
     effluent.
b/ Considerable turbidity was noticed in these samples.
                                                      Initial

                                                        4.0
                                                        2.1
                                                        6.4^
                                                        6.^a
             Final
               2.8
               7.2
               6.6
               2.7
               2.9
          In this first series of experiments,  the observation was made that
significant quantities of ammonia were oxidized to nitrate in the experiments
in which the effluent was exposed to UV radiation and chlorine (Experiments
3 and 4); there were  substantial increases in nitrate concentration  (Table V)
Chlorine in the dark also produced an increase in nitrate concentration
(Experiments 7 and 8), but this increase was not as great as that produced
by chlorine plus irradiation.  UV radiation alone actually decreased the
nitrate concentration.  This observation was confirmed in Experiment 15,
p. 115.  The formation of nitrate in the ammonia-chlorine reaction was in-
vestigated further in subsequent experiments (see the two sections of this
report concerned with the oxidation of high-ammonia effluents, p. 49, and
the section concerned with the ammonia-chlorine reaction, p. 54).
                                 TABLE V
  3
  4
  5
  6
  7
  8
                          NITRATE CONCENTRATIONS
                        (First Series of Experiments)
            Reaction Conditions
Initial C12 Types of
Concn. (ppm) pH Irrad.
150
150
0
0
150
150
5
10
5
10
5
10
UV
UV
UV
UV
None
None
                                        Reaction Time
                                           (min.)

                                              27
                                              20
                                             196
                                             145
                                           1,341
                                           4,535
                                                         Nitrate  (ppm H)
                                                        Initial      Final
0.50

0.50

0.26
2.44
2.85
0.20
0.09
1.95
1.27

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100
 90 —
                                                                    —  90
                                                                        100
                 Figure  1 - Relative Amounts of HOC1 and OC1"
                                at Various pH Levels
                                      10

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      I     I     I     I    1	I	I	I	I	I—I
     240       260      280       300

        WAVELENGTH  (millimicrons)
Figure 2 - Ultraviolet  Spec.tra of Hypฐchlorous
              Acid  and  Hypochlorite Ion

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                            Time (min.)
Figure 3 - UV-Catalyzed  Chlorine  Oxidation of Effluent
                Cr-1  at pH 5  (Experiment 3)

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I  100

_o
-C
L
                                                                            30
          15
20
Q_

c
:
.
    E
    Q.
10 <ฃ
   u
    :
                                                                            10

                                                          20
                                        Time (min.)
                 Figure 4 - UV-Catalyzed Chlorine  Oxidation  of Effluent

                                    G-l at pH  10  (Experiment 4)


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                    Time (min.)
Figure 5 - Ultraviolet Irradiation of Effluent

               G-l at pH 5 (Experiment 5)
                                                              E
                                                              D.
                                                             c
                                                             0
                                                        - 10
                                                           0
                        14

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   15 -
 a
U
0
                                      Time (min.)
                  Figure  6  -  Ultraviolet  Irradiation of Effluent

                               G-l  at pH 10  (Experiment  6)
                                                                                 O
                                                                                 0
                                                                                 U
                                                                           -  10
                                               15

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                                             COD
                                                                         30
                                                                          20
                        I
                        Q.


                        8
                        L

                                                                                       a.
                                                                                       (.
50
                                                                          10
 ;
                           500
                                      Time (min.)
,000
                                                                                     ]
,500
                     Figure 7 - Chlorination of Effluent G-l

                                    at pH 5 (Experiment 7)
                                          16

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                                                  COD
                                                                              30   -

                                                                                  a
                                                                                  Q-

                                                                              20 ~H


                                                                                 0
                                                                                 I
                                 10
                 E
                 •..:.
                 1.


                u

                0
50
                                                                               10    -
                            500
1,000
                                         Time (min.)
	L


 4,335
                                                                               0
                      Figure 8 - Chlorination of Effluent G-l

                                    at pH 10 (Experiment 8)

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           SECOND SERIES OF WASTEWATER OXIDATION EXPERIMENTS
                                 Summary
          Experiments performed in this series indicated that,  in the  UV-
catalyzed process, the extent of organic oxidation is proportional to  the
irradiation time, but not to chlorine concentration.  The  catalytic oxida-
tion rate is faster at pH 6.5 than at pH 8.5; the average  extent  of COD
decrease produced in 10 min. was 60.0$ at pH 6.5 and 45.6$ at pH  8.5.
(The organic oxidation rate is fastest at pH 5, and experiments performed
at pH 5 are described in the third series of wastewater oxidation experi-
ments.)

          Experiments performed in this series and in the  third series
have indicated that considerable variation exists in the amount of organic
oxidation which can be achieved when wastewater samples are treated for
10 min. with chlorine in the dark.  In 13 experiments employing six dif-
ferent effluents, the extent of COD elimination during 10  min.  in the  dark
averaged 12% (range 0.8-20$) and the extent of TOG elimination  during
this time averaged 6$ (range 0-15.3$).
                                    18

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Second Series of Wastewater Oxidation Experiments

          The low-ammonia effluents used in the second series of experi-
ments were obtained from two sources.  First, a laboratory-scale activated
sludge apparatus was constructed and used to reduce the ammonia content of
high-ammonia municipal effluents.  (This apparatus is described in the
Experimental Section.)  Second, a reliable source of the desired type of
highly nitrified effluent was located.  This source was a sewage treatment
plant of the activated sludge, extended aeration type.  The plant was of
novel design and was operated on an experimental basis by the Smith and
Loveless Corporation.

          Our experimental work continued using effluents obtained from
both of these sources.

          A series of nine, effluent, oxidation experiments was designed to
investigate simultaneously the effect on COD and TOG of two levels, each,
of chlorine concentration, irradiation time and pH.

          The chlorine concentrations investigated consisted of (l) a
slight excess over the theoretical amount of chlorine, and (2) a large
(75$) excess over the theoretical value.

          Irradiation times of 10 and 15 min. were examined to determine
whether or not significant differences in COD and TOC elimination are
caused by differences in irradiation time of this magnitude.  In these
experiments the UV lamp was allowed to warm up and was emitting maxisium-
intensity radiation when inserted into the reactor.

          The pH levels of 6.5 and 8.5 were selected for study.  These
values are only about 1 pH unit different from the pH of the untreated
effluent, but variations of this magnitude could have a large effect on
the oxidation reaction; at pH 6.5 about 90% of the available chlorine is
present as undissociated hypochlorous acid and, at pH 8.5, about 90$ of
the available chlorine exists as hypochlorite ion (see Figure l).

          A complete factorial experiment was designed, and the order of
experiments was randomized.  The design and randomization of the experiments
are shown in Table VI.  The numbers refer to actual experiment numbers; that
is, Experiment 39 was run first, and Experiment 47 was run last in this
series.

          In Experiment 41, no chlorine was used, no pH adjustment was made,
and the effluent was exposed to UV radiation for 10 and 15 min.
                                  19

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                                TABLE VI

                          EXPERIMENTAL DESIGN
                         (Experiments 39 - 47)

                                    _     pH 6.5	        PH 8.5	
                                    High Cl2   Low Cla   High C12   Low  C12
                                   (175 ppm)  (102 ppm)   (175 ppm)  (102  ppm)

Short irradiation time (10 min.)      43ง/       46         47          40

Long irradiation time (15 min.)       44         45         39          42
a/  The numbers 39-47 refer to experiment numbers.   The  experiments  were
      performed in random order and are numbered in the  order in which
      they were performed.
          The effluent  (S&L-5)  used  in  these experiments was obtained
from the Smith and Loveless, experimental, sewage-treatment plant.  This
effluent was very highly nitrified; the ammonia content was less than 1 ppm
(N), and the nitrate  content was 10.6 ppm (N).  The average COD was 22.0 ppm.

          The results of this series of experiments are presented in the
following tables.  Table VTI shows the extent of COD elimination produced
in the dark and upon  subsequent irradiation.

          Reaction in the  dark  - The results shown in Table VII indicate
that substantial elimination of COD occurred during the initial period of
chlorination in the dark.   In some of the experiments, the indicated
decrease in COD was equal  to—or even greater than—the subsequent COD
decrease which occurred upon irradiation.  Although not all the experiments
show large COD decreases during this period,, (in fact, some ,show slight
increases), there appears  to be a statistically significant difference
between the analytical  figures  obtained before and after chlorination in
the dark; the average COD  before chlorination was 20.8, the average after
chlorination was  16.2.   The difference between these figures represents
a 22$ average decrease  in  COD.  A comparison of these averages  is prob-
ably valid because it is not possible to correlate the individual COD
decreases with differences in pH or differences in chlorine concentration.
                                   20

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                               TABLE VII
                      EXTENT OF COD ELIMINATION
                Initial
               Chlorine
Expt.
No.
39
40
41
41
42
43
44
45
46
47
Concentration
pH
8.5
8.5
7.5
7.5
8.5
6.5
6.5
6.5
6.5
8.5
(ppm)
175
102
0
0
102
175
175
102
102
175
Ultraviolet
Irradiation
   Time
  (min.)

     15
     10
     10
     15
     15
     10
     15
     15
     10
     10
  Extent
  of COD
Elimination
 in Darkฃ/
  Extent of COD
Elimination After
Treatment in the
 Dark and After
  Irradiation^/
                                           -5.23
         M
         27.1
         33.3
      49.5
      43.2
+0.61
-2.70
+0.29
-1.84
+0.70
-1.98
-6.35
-5.55
^J
cj
O^/
10.3
oV
9.4
30.1
29.9
                                                                 13.0
                                                                 35.7
                                                                 52.0
                                                                 59.6
                                                                 68.8
                                                                 59.5
                                                                 53.8
a/  The percentages were calculated after adjusting the initial COD
      values to account for the dilution which occurs when chlorine
      water is added.
b/  In these experiments, the slight increase in COD which was detected is
      within the range of experimental error.
c/ No "reaction in the dark" preceded irradiation.

          However, we do not believe that the extent of oxidation in the
dark was as great as these figures indicate.  The main reason for doubt
is that the amount of chlorine consumed during the same period is not
sufficient to produce COD decreases of this magnitude.  The elimination of
1 ppm of COD requires 4.43 ppm of chlorine.  Inspection of the data
presented in Table VIII clearly shows that the apparent COD elimination in
this series of experiments was far greater than that which could be produced
by the amount of chlorine consumed.

          The apparent loss of COD in the dark was probably caused by a
loss of volatile organic matter during the nitrogen purge.  Except for the
first sample (which obviously does not require dechlorination) and the
final sample (which usually contained only traces of chlorine), each sample
was acidified and purged with nitrogen in order to remove chlorine.  We
believe-that this particular effluent was unique in that it contained rela-
tively large quantities of volatile organic products.
                                    21

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                                TABLE VIII

                COMPARISON OF COD ELIMINATION WITH CHLORINE
                         CONSUMPTION IN THE DARK

                          Theoretical COD Elimination
           Chlorine              Equivalent to                Observed
Expt.     Consumption        Chlorine Consumption         COD Elimination^/
Mo-           (ppm)        	(ppm)	          (ppm)	

 39             7                   1.58                       5.23
 40            10                   2.26                       7.55
 42             3                   0.68                        {ฃ/
 43             8                   1.81                       1.84
 44             3                   0.68                        oV
 45             7                   1.58                       1.98
 46             7                   1.58                       6.35
 47             5                   1.13                       5.55
a/  Initial COD values were adjusted to account for the dilution which
      occurs when chlorine water is added.
b/  In these experiments, the slight increase in COD which was detected
      is within the range of experimental error.
           In general,  the TOG analyses  (Table IX) also show significant de-
creases during the 10-min. period in the dark.  (Unfortunately,  some  of the
TOG analyses  in this series were obviously too high and had to be  discarded.)
However, the  TOG samples were  taken at the same time as the COD  samples, and
the two samples were subjected simultaneously to the dechlorination proce-
dure.  Therefore, the TOG data are subject to the same errors as the  COD
data.

          In  subsequent experiments, the TOC samples were  taken  separately
and dechlorinated by acidification (to pH 1 with 1^304), followed  by  treat-
ment with excess sodium bisulfite.  This procedure could not be  used  for
the COD samples because excess bisulfite would interfere with the  COD
determination.

          These subsequent experiments provided considerable information
concerning the extent of oxidation which takes place during a 10-min. period
of chlorination in the dark.   From a total of 13 experiments with  six dif-
ferent effluents, the following observations were made:  (l) during the 10-
min. period of chlorination in the dark, the extent of COD reduction  averaged
12$ and ranged from 0.6-20$;  (2) the extent of TOC reduction during this
time was, in general, less than the extent of COD reduction. The  TOC reduc-
tion averaged 6$_ and ranged from 0-15.3$.

                                     22

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                                TABLE IX
                                                          fi/
                EXTENT OF TOG ELIMINATION  IN THE  DARK AND
                             UPON IRRADIATION
Initial
Chlorine
Concentration
(ppm)
175
102
0
0
102
175
175
102
102
175
Ultraviolet
Irradiation
Time
(min. )
15
10
10
15
15
10
15
15
10
10
Extent of
TOG Elimination
in Dark
(*)
-8
-33
-
-
-4
+3 /
-eฃ/
+9
+14
-22
Extent of
TOC Elimination
on Irradiation
(*)
V
V
-10
-19
-35
-25
-soฃ/
+12
-17
-26
 39     8.5
 40     8.5
 41     7.5
 41     7.5
 42     8.5
 43     6.5
 44     6.5
 45     6.5
 46     6.5
 47     8.5

~^JInitial TOC values were adjusted to account for the dilution vhich
      occurs when chlorine water is added.
b/  The calculations for these experiments could not "be made "because the
~~     TOC  results were obviously in error.
c/  These  values were calculated assuming that the actual initial TOC in
      Experiment 44 was equal to average initial TOC value  (9.11 ppm).


           A  summary of data concerning the  extent  of oxidation in the
dark  is presented in the Experimental  section  (see- "Extent  of Oxidation
Produced by  Chlorine in the Dark," p.  107).

           Reaction during  irradiation  - When the UV lamp was  'placed in
 the immersion well, the chlorine concentration began to  decrease rapidly
 (Table X).  By  far the greatest percentage  of  available  chlorine was con-
 sumed during the" first 5 min.  Almost  all the  remaining  chlorine was con-
 sumed during the second 5  min.;  and,  in almost every case,  the small amount
 of residual  chlorine was consumed  during the final 5 min. of  irradiation.

           The extent  of chlorine  consumption during the  first 5 min.
 (Table  XI) was  directly proportional  to the chlorine concentration  and  was
 not related  to  the  difference in pH.   The extent  of chlorine  consumption
 during  the second  5 min. was  likewise  directly related to the amount of
 chlorine present.

                                     23

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                                 TABLE X
                     CHLORINE CONSUMPTION IN THE DARK
AND DURING IRRADIATION

Expt.
No.
39
40
42
43
44
45
46
47
Initial Chlorine
Concentration
(ppm)
175
102
102
175
175
102
102
175
Chlorine Consumption (ppm)^'
In the Dark
(10 Bin.)
7
10
3
8
3
7
7
5

0-5 min
112
70
72
95
114
72
63
118
Upon Irradiation
5-10 min. 10-15 min.
31 6
24
24 3
60
54 7
14 1
30
47
"aT  In experiments  in which  the chlorine concentrations were not determined
~~     exactly at 5-min.  intervals, the chlorine consumption during these
      periods was estimated.
                                  TABLE XI

                  CHLORINE CONSUMPTION (PPM) DURING FIRST
                        FIVE MINUTES  OF IRRADIATION
                            (Experiments  39-47) a/
          At pH 6.5
                              At pH 8.5
 175 ppm Cl2     102 ppm Cl2
      95 (43)

     114 (44)
63 (46)

72 (45)
175 ppm Cl2
118 (47)
112 (39)
102 ppm Cl2
70 (40)
72 (42)
 a/  The individual experiment numbers  are shown in parentheses.
                                     24

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          Since practically all the chlorine was consumed during the first
10 min., the extent of organic oxidation during the 10-min.  experiments
would be expected to be similar to that which occurred during the 15-min.
experiment.  (As discussed below,  the extent of organic oxidation produced
by UV-radiation alone during the third 5-min. period would not be significant.)
This postulation is confirmed by the results shown in Table  XII.

          Also indicated by the results presented in Table XII is the con-
clusion that no particular benefit is derived by the presence of a large
excess of chlorine.  This is perhaps the most important conclusion derived
from this series of experiments.

          Another conclusion drawn from the results shown in Table XII is
that the oxidation is more effective at pH 6.5 than at pH 8.5; the average
COD decrease at pH 6.5 was 60.0%,  the average COD decrease at pH 8,5 was
45.6$.  For these calculations, the results of both the 10-min. and the
15-mino experiments were combined.  The results, 60.0% and 45.6$, are the
approximate amount of COD elimination produced in 10 min. because, as indi-
cated in Table X  (p. 24), the chlorine had been almost completely consumed
at the end of 10 min.  As discussed below, an insignificant  amount of
COD elimination would be expected during the final 5 min.
                                TABLE XII

             PERCENT ELIMINATION OF COD DURING IRRADIATION
                           (Experiments 39-47)

   Total
Irradiation        	At pH 6.5	     	At pH 8.5	
 Time, min.        175 ppm Gig    102 ppm Clg     175 ppm Clg    102 ppm Cl2

   10                 52.0           59.5             53.8          43.2

   15                 59.6           68.8             49.5          35.7
                                   25

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          Effect of irradiation alone  - In Experiment 41, the effluent was
irradiated as in the other  experiments, but no chlorine was added.  After
10 min., there was no detectable decrease in COD (the analytical results
actually indicated 2.9$  increase in COD which is considered to be within
the range of experimental error).  However, the TOC decrease was
10.4$.  After 15 min., the  COD decrease amounted to 13.0$ and the TOC
•decrease was 18.8$.   (Since the TOC decrease cannot theoretically exceed
the COD decrease, one of these analytical results is obviously inaccurate.)

          A comparison of the average  COD decrease produced in 10 min. at
pH 6.5  (60.0$) with the  COD decrease produced by UV radiation alone during
this  time  (2/3 x 13.0$ = 8.66$) indicates that chlorine plus UV radiation
is about seven times more effective than radiation alone.  This result is
consistent with the results of the first series of exploratory experiments,
which indicated that  chlorine plus UV  radiation eliminated COD 10 times
faster than radiation alone at pH 10,  and more than eight times faster
than  UV radiation alone  at  pH 5.
                                   26

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             THIRD SERIES  OF WASTEWATER  OXIDATION EXPERIMENTS
                                Summary


          In the UV-catalyzed chlorine oxidation of wastewater,  the organic
oxidation rate is faster at pH 6.5 than at pH 3;  and is  faster at  pH 5  than at
pH 3 or pH 10.

          Large excesses of chlorine do not increase the organic oxidation
rate, except at pH 10.  Most efficient use of chlorine was obtained when
chlorine was added gradually during the irradiation period.

          At pH 5 and pH 6.5, the rate of COD elimination is most rapid
during the first 5 min. and decreases as the reaction proceeds.   The elimi-
nation of TOC is approximately linear over a 15-min. irradiation period.

          At pH 5, the  average COD  elimination was  67$  in  5 min.  (range
51-84$),  79$ in 10 min. (range 66-100$),  and 94.5$ in 15 min.  (range 88-
100$).   The average  TOC decrease was  33$  in  5 min.  (range  15-50$), 52$ in
10 min.  (range  44-60$)  and 75$ in 15  min.  (range  70-81$).

           In  the UV-catalyzed chlorine  oxidation process,  the rate and ex-
tent of  organic  oxidation  is  not  affected by temperature within the  range
5ฐ-25ฐC  (41ฐ-77ฐF).
                                     27

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Third Series of Wastewater Oxidation Experiments

          Some important questions were generated by the preceding series
of experiments.  Perhaps the most important question was "What extent of
COD and TOG elimination occurs during the first 5-min. period of irradiation,
the time during which the largest amount of chlorine is consumed?"  Two
other related questions were "Is the amount of organic material oxidized
proportional to the amount of chlorine consumed?" and "Given a large excess
of chlorine and an extended period of illumination, can all the organic
material "be eliminated?"  Another important question was "Since pH 6.5 ap-
pears more effective than pH 8.5, would a further decrease in pH be even
more effective?"

          Experiments  48 and 49  - These experiments were designed to answer
the above questions.  Both experiments were performed using an effluent
(S&L-6) which was obtained from the same source as the effluent used in Ex-
periments 39-47.  In Experiment 48 the pH level was maintained near 3.0,
and samples were withdrawn at 5-min. intervals.  Samples for TOG determin-
ation were not dechlorinated by nitrogen purge, but were treated with ex-
cess sodium bisulfite  and acidified to pH 1 with HgSO^  Experiment 49 was
similar, except that the pH was maintained at 6.5.

          The results  of these experiments are shown in Figures 9 and 10.
The effect of pH on COD and TOG  elimination was very marked.  At pH 3.0,
there was a  33$ drop  in COD  and  a  12$ drop in TOG after 10-min. illu-
mination.  However, at pH 6.5, the COD elimination amounted to 72%, and the
TOC elimination amounted to  54$  during the same length of time.

          Moreover, after only 5 min. at pH 6.5, the COD elimination amounted
to 44$  and the TOC elimination amounted to 38$.  These results clearly show
that the oxidation is much more  effective at pH 6.5 than at pH 3.0.

          The role of  excess chlorine was further clarified by these ex-
periments.  After all the initial chlorine had been consumed, an additional
amount  of chlorine approximately equal to the initial chlorine dose was added
to the  reaction mixture.  As is  evident in Figures 9 and 10, no significant
acceleration of either the COD or TOC elimination was caused by this addi-
tion of excess chlorine.

          The results of these two experiments and the preceding series of
experiments (Experiments 39  - 47) indicate clearly that the presence of ex-
cess chlorine is of no particular value.

          Experiment 49 indicates that, at pH 6.5, the rate of oxidation of
organic matter, as measured by both COD and TOC, decreases as the reaction
progresses.  In subsequent experiments at pH 5, the rate of COD elimination

                                    28

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also decreased with time, tut the rate of TOG elimination was approximately
linear.  Apparently, the organic constituents in a particular effluent vary
widely in regard to the rate at which they are oxidized.  Thus, the overall
rate of oxidation decreases as the more-easily-oxidized material is consumed.

          Also clarified by these experiments is the role of pH; decreasing
the pH from 6.5 to 3.0 (Experiments 48 and 49), or raising the pH from 6.5
to 8.5, (Experiments 39 - 47) produces significant decreases in the oxida-
tion rate.  These conclusions were further substantiated in Experiments 52 -
54, described below.

          Experiment 50 - The primary objective of Experiment 50 was to
confirm the results of Experiment 49 using a municipal effluent which had
been further processed in our laboratory-scale,  extended-aeration apparatus.

          The results (Figure 11) confirm that a very large proportion of
the total COD and TOG elimination does occur during the first 5 min. of
irradiation.  Tables XIII and XIV present the results of experiments
49 and 50.

                                TABLE XIII

              UV- CATALYZED CHLORINE OXIDATION OF AH EFELUEKT
               OBTAINED FROM A LAEGE, SEWAGE -TREATMENT PLANT
                 ("Effluent S&L-6, pH 6.5, Experiment 49)

                          Chlorine           COD                TOG
                         Consumption     Elimination        Elimination
Reaction Period            (ppm)         (ppm)    TJ-      (ppm)
During 10 min.
  in dark                    10           0.2     0.8       0.04     0.5
During first 5-min.
  irradiation                80          11.1    44.0        2.8    37.7
During second 5-min.
  irradiation                55           7.0    27.7        1.2    16.1
Totals after
  20 min.                   125          18.3    72.5       4.04    54.3
a/  The percent figures were calculated by dividing the amount  of COD
     .(or TOG) eliminated during each 5-min.  interval by the  original
      COD (or TOG) value (corrected for the dilution effect caused by
      added chlorine).
                                   29

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                                TABLE XIV

          UV-CATALYZED CHLORINE OXIDATION OF AN EFFLUENT FROM
              A LABORATORY-SCALE, SEWAGE-TREATMENT APPARATUS"
                (Effluent MRI-428, pH 6.5, Experiment 50)

                          Chlorine           COD                TOC
                         Consumption     Elimination        Elimination
Reaction Period            (ppm)         (ppm)    ($)*/     (ppm)     (%)ฃ./

During 10 min.
  jn dark                     6          0.76     2.9
During first 5-min.
  irradiation               137         19.43    73.5
During second 5-min.
  irradiation                21          2.72    10.2
Totals after
  20 min.                   164         22.91    86.6        7.2    68.1
a/  The percent figures were calculated "by dividing the amount of COD
~      (or TOC) elimination during each 5-min. interval by the original
       COD (or TOC) value  (corrected for the dilution effect caused "by
       added  chlorine).
           Three  important  observations were made, based on the results of
Experiments  49 and  50.

           (l)  There was very little consumption of chlorine or elimination
of COD or  TOC during the 10-min. period of chlorination in the dark.  Thus,
these  two  effluents contained relatively small amounts of organic material
which  could  be oxidized in the dark.  As discussed in the previous section,
the average  amount  of TOC  and COD  elimination produced during the 10-min.
period of  chlorination  in  the dark was 10$.  (See Experimental Section,
"Extent of Organic  Oxidation Produced by Chlorine in the Dark",  p.  108.)

           (2)  Large amounts of TOC and COD elimination were produced dur-
ing the initial  5-min.  period of irradiation.  For the Smith and Loveless
effluent,  44$ COD elimination and  38$ TOO  elimination occurred  during this
time.   For the effluent produced in the laboratory-scale, activated-sludge
apparatus, 74$ COD  elimination and 44$ TOC elimination was  produced
during this  initial 5-min. period  of irradiation.
                                     30

-------
          (3)  Less COD and TOG elimination is produced during the second
5-min. period of irradiation.  Elimination of COD during the second 5-min.
period was 27.7$ for the Smith and Loveless effluent, and 10.2$ for the
laboratory-produced effluent.  Elimination of TOC during this time was
16.1$ for the Smith and Loveless effluent, and 18.9$ for the laboratory-
produced effluent.

          Further investigation of the effect of pH - Three experiments
(Experiments 52 - 54) were designed to investigate the rate and extent of
W-catalyzed chlorine oxidation at pH 3, pH 5 and pH 10.  The effluent
(MRI-512) used in these experiments contained 33.8 mg/liter COD, 13.2 mg/
liter TOC, 2.5 mg/liter ammonia nitrogen  and  4.0 mg/liter nitrate  nitro- ,
gen  (average values).  It had been produced in our laboratory by passing
high-ammonia municipal wastewater through the laboratory-scale, activated-
sludge  apparatus.   In each experiment the effluent was treated with chlorine
water to provide  an initial  chlorine concentration of about 200 ppm.  This
concentration  represents a 33$ excess over the theoretical amount  of  chlo-
rine required  to  oxidize all of the organic material to  C02 and HgO.  The
results of  a second addition of chlorine  will be discussed in  the  next sec-
tion, "Effect  of Chlorine  Concentration", p.  32.

          The  experiments  were performed  at room temperature  and were iden-
 tical,  except  that each was performed at a different pH (pH 3, pH 5,  and pH
 10). 'During the 10-min. period of chlorination  in the dark,  the  average
 chlorine concentration decreased  about 26 ppm.   During this  time,  there  was
 an average  decrease in COD of 3.6 mg/liter (12$)  and an average decrease in
 TOC of 0.3 mg/liter (3$).   These  results in the  dark were about the same in
 each experiment, except that the  chlorine consumption and the extent  of  TOC
 decrease were  somewhat greater at pH 10.

           The results of these experiments are shown in Figures 12 -  14,
 and  the data are summarized in Figures 15 and 16.  The results presented in
 Figure 15 indicate that the rate of COD elimination upon irradiation  is  the
 fastest at pH 5; approximately 70$ of the COD present after treatment with
 chlorine in the dark was eliminated during 5 min. of irradiation, and 80$ was
 eliminated within 10 min.

           The extent of TOC elimination  in these experiments is shown in
 Figure 16.  These  results are in agreement with the COD data; more rapid
 TOC  elimination  is produced at pH 5 than at pH 3 or at pH 10.  However,  the
 extent of TOC elimination is  not as great as the extent of COD elimination.
 A curious  fact  is  that the  TOC plots are almost linear, while the rate of
 COD elimination  decreases as  the oxidation proceeds.
                                      31

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           In these  three  experiments,  the  rate  of chlorine consumption was
 about  the same at all pH  values;  about two-thirds of the initial  chlorine
 was  consumed after  5 min. of irradiation,  and practically all the initial
 chlori-e was consumed after 10  min.  of irradiation.  Obviously, because of
 the  large extent of organic oxidation, the most efficient utilization of
 chlorine was obtained at  pH 5.

           Subsequent experiments  have  confirmed that pH 5 is the optimum
 pH for the most efficient chlorine utilization  and organic oxidation.  These
 experiments are described in detail  later  in this report, and a summary of
 the  data concerning the extent  of organic  oxidation is presented in the
 Experimental section (see "Extent of COD and TOC Elimination Produced
 by Irradiation at pH 5",  p. 109). Seven experiments, using four different
 effluents, are compared.   The data are  presented graphically in Figures 17
 and  18.

           These figures show that the  average COD elimination at pH 5 is
 67%  in 5 min.,  79%  in 10  min. and 95$  in 15 min.  The concurrent TOC elimina-
 tion is  55% in 5 min., 52% in 10  min.  and  75% in 15 min.

           The data  presented in these  figures (Figures 17 and 18)  confirm
 the  observations of Experiments 52 - 54 that the rate of  COD elimination
 decreases as the oxidation proceeds, but that the rate of TOC elimination
 is linear.

           Effect of chlorine concentration - In general,  the elimina-
 tion of  COD and TOC and the consumption of chlorine are most rapid at the
 beginning of the UV-catalyzed oxidation.  However,  the rate of organic oxi-
 dation is not directly proportional  to  the chlorine concentration; in the
 second series of eight experiments described in the preceding section, a
 75$  excess of chlorine produced no more organic oxidation in 10 min. than
 did  a  stoichiometric amount of  chlorine.

           The results of  other  experiments in this  series have indicated
that large increases in the initial  chlorine concentration  do not  produce
 correspondingly large increases in organic oxidation rates.  In Experiments
48 and 49,  a  second addition of chlorine approximately equal to the origi-
nal amount  of chlorine was  added  to  the reaction mixtures after the reac-
 tion mixtures had been irradiated for about 10 min.   No significant increase
 in organic  oxidation rate was observed.

           In Experiments  52 - 54, a  second addition of chlorine was made,
and the results  at pH 5 (Experiment 54) and at pH 3 (Experiment 52)  were
similar to the results of Experiments 48 (pH 3.0) and 49  (pH 6.5).  How-
ever, at pH 10 (Experiment  53), the second addition of chlorine actually
did increase  the rate of  COD elimination.  The rate of TOC elimination,
however, was not affected.
                                     32

-------
          Analysis of the above results indicates that, at pH values between
5.0 and 8.5, (l) only a certain minimum concentration of chlorine is re-
quired for maximum oxidation rate, and (2) concentrations of chlorine above
this minimum are wasteful.
          These conclusions are substantiated by an experiment (Experiment
78) in which the chlorine water was not added in one portion, but was added
gradually in increments during the irradiation period.  The results, pre-
sented in Figure 19, show conclusively that extensive elimination of COD
(88$ in 15 min.) and TOG (70% in 15 min.) can be achieved even when the con-
centration of chlorine does not exceed 36 ppm.  The amount of chlorine con-
sumed in this reaction was equivalent to approximately 89$ of the total
amount added.  This amount of chlorine is only slightly in excess of the
theoretical amount of chlorine (145 ppm) required to eliminate all of the
original COD (32.9 ppm).

          Thus, for the most  efficient  use  of chlorine, a  gradual  addition of
chlorine during irradiation is necessary.

          The chlorine consumed, but yet not accounted for by an equivalent
amount of organic oxidation, is most probably consumed by auto-decomposition
reactions.  The fact that chlorine is decomposed by ultraviolet radiation is
well known, and the products are known to be chloric acid, hydrochloric acid
and oxygen.ฃ/  The extent to which chlorine alone is decomposed in our reac-
tor is shown in Figure 20.  Note that the decomposition is very much faster
at pH 10 than at pH 5.

          Effect of nitrate concentration - Because effluents contain
varying concentrations of nitrate, it was important to learn whether or not
variations in nitrate concentration could be responsible for observed vari-
ations in the rates of COD and TOC elimination.  In one experiment  (Experi-
ment 77, Figure 21), 20 ppm of nitrate nitrogen (as potassium nitrate) was
added to an effluent prior to treatment with chlorine.  The effluent (S&L
624A) was the same as the one used in Experiment 75 (Figure 22).  A com-
parison of Figures 21 and 22 shows that the rate of COD elimination and the
rate of chlorine consumption are practically the same in each experiment.
Therefore, within the range of 4-20 ppm, nitrate concentration has no effect
on the rate or extent of the UV-catalyzed chlorine oxidation.
                                    33

-------
          Effect of temperature - Two effluent oxidation experiments
(Experiments 58 and 59) were performed in exactly the same manner,  except
that in one the temperature was held near 5ฐC (41ฐF) and in the other the
tempera "cure was held near 25ฐC (?7ฐF).  The results are shown in Figures
23 anc1 24.  These figures show that the rate of chlorine consumption, rate
of COD elimination, and  rate of TOG elimination are practically the
same at "both temperatures.  The temperatures of most effluents from extended
aeration processes would be within the temperature range investigated.
Therefore, in actual operation, ordinary temperature changes should have
no effect on the rate of effluent oxidation.
                                    34

-------
140 -
                                                                Additional
                                                                Chlorine
                                                 Lamp Off
                           10
15
30
35
40
                                 20          25
                                    Time (min.)
Figure 9 - UV-Catalyzed Chlorine Oxidation of Effluent S&L-6-A at pH 3.0  (Experiment  48)

-------
                                   Additional
                                 Chlorine Added
            Lamp Off
1

—
-
-
—
-
,_
—
_
—
—
—
1
JU
28
26
24
22
20
18
16 •ฃ -
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10
8
6
4
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7

6

5

A
EL
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1


                                20         25
                                   Time (min.)
30
35
40
Figure 10 - UV-Catalyzed Chlorine Oxidation of Effluent  S&L-6-A  at  pH 6.5  (Experiment 49)

-------
(,,
 I

I
160


140
1
120


3 10ฐ
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60

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24 -
22 -

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18 -
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                 Figure 11 -
                           Time (min.)

UV-Catalyzed Chlorine Oxidation of Effluent MRI-428 at pH 6.5  (Experiment  50)

-------
i,,
'.
                                                                      Additional

                                                                       Chlorine
                                                                                                               - 2
                                                                                                                  0 —
                                             15
30
35
40
                                20         25

                                     Time (min.)


Figure 12 - UV-Catalyzed  Chlorine  Oxidation  of Effluent MRI-512 at pH '6  (Experiment  52)

-------
,
      320  -
                             Lamp Inserted
Additional
Chlorine
                                10
                             15
40
                                                                                                                    0 —
                        15         20         25
                                    Time (min.)
Figure 13 - UV-Catalyzed  Chlorine Oxidation of Effluent MRI-512 at pH 10  (Experiment  53)

-------
320
280  -
                                                      Additional
                                                       Chlorine
                         10
20
 25         30
Time (min.)
40
                                                    -32    -
                                                    -  28   -
                                                      U>
                                                      14
                                                                                                             10

                                                                                                               T
                                                                                                             8 *
                                                                                                             0	
          Figure  14  -  UV-Catalyzed Chlorine Oxidation of Effluent MRI-512 at pH 5  (Experiment  54)

-------
c
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                                        B
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                                        "5
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                                        (U
                                         I
                  4         8

                   Time (min.)
                                             80 .
                                                I
               4         8

                 Time (min.)
 Figure  15  -
Extent of Chemical Oxygen Demand

(COD) Elimination Produced by UV-

  Catalyzed Chlorine Oxidation
Figure 16 - Extent of Total Organic Carbon  (lOC)

            Elimination Produced by UV-Catalyzed

                  Chlorine Oxidation

-------
I
r i
          C
          01
                                                                   0
                o
5         10


   Time (min.)
                                                                  20
                                                                   40
                                      c
                                      II
                                      U

                                      0)

                                      ฐ-  60
                                                                   80
                                                                  100
                                                T	1	T T"  ~T  T
0
                                                                                                 PH5
                                                                           I     I     I     I      I
5         10

    Time (min.)
15
                Figure 17 - Average Percent of COD Eliminated

                                 Upon Irradiation at pH 5
                                         Figure 18 - Average Percent of TOG Eliminated

                                                          Upon Irradiation at pH 5

-------
 Lamp

Inserted
                       1C
15

 Time (min,)
                                                      25
                                                                 24
                                                                 20
                                                                     a.
                                                                     a_

                                                                 16  0  I
                                                                     o
                                                                     u


                                                                 12     H
                                                                  0
                                          12
                                          10
                                              a

                                           8 .*
                                              U
                              30
35
      Figure 19 - UV-Catalyzed Chlorine Oxidation   : Effluent S&L-624-A  at

                         pH 5 With Continuous Adc:' "ion of Chlorine

                                      (Experiment  78)
                                            43

-------
             10
15         20
   Time (min.)
25
Figure 20 - Rates of Chlorine Decomposition During Irradiation at
                            pH 5 and at pH 10
                                 44

-------
i •
i ii
         180
        160
                              Lamp Inserted
         Additional

          Chlorine
                                 10
15
30
                  Figure 21 -
                        20

                    Time (min.)

UV-Jatalyzed Chlorine  0;:idatiori of Effluent  G&L-S24-A, C

   20 ppm of Added  Hitrate Hitro^rii, at pfl ,5 (Experiment 11')
                                                                                                 H 14
                                                                                                 -  12
                                                                                                 -  10
                                                                                                        !
                                                                                                        ' '
                                                                                                        Q_


                                                                                                       I '

                                                                                                       0
                                                                                                 -  6
                                                                                                 -  4
                                                                                                 -  2

-------
!
         180 r-
                                                         Additional
                                                          Chlorine
          20  -
                                                                            30
                                                                                              H  28
35
                          15         20         25
                                        Time (min,)
:   n     -       italyzed  Chlorine 0> ;                   ,  !      i-A at pit 5  (Experiment 75

-------
                         Lamp Inserted
260
220

—
—

	
1
28
24
20
16 ~ -
CL
CL
.Q
o
12 U ~
8
4
30
14
12
10
a !
Jl
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2
0
                                       15          20          25
                                                    Time (min.)
       Figure  23  -  UY-Catalyzed Chlorine Oxidation of Effluent MRI-525 at pH 5 and 5ฐC (Experiment 58,

-------
0
—
—
—





1
28
24
20
16 •ฃ-
Q.
Q
12 u-
8
4
14
12
10
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                                                       20         25        30
                                                         Time (min.)
             Figure 24  - UV-Catalyzed Chlorine  Oxidation-of Effluent  MRI-525  at  pH 5  and 20ฐ-25ฐ  (Experiment 59)

-------
                ULTRAVIOLET-CATALYZED  CHLORINE  OXIDATION
                       OF  HIGH-AMMDNIA EFFLUENTS
                                 Summary
          The presence of ammonia in an effluent drastically reduces the
rate and extent of UV-catalyzed chlorine oxidation of organic matter.
For example, the addition of 23 ppm of ammonia nitrogen to a highly nitri-
fied effluent reduced the organic oxidation rate "by more than tenfold.
The amount of chlorine actually required to eliminate 1 ppm of ammonia
in the UV-catalyzed process is about four times the theoretical amount
required to eliminate 1 ppm of COD.
                                    4-9

-------
Ultraviolet-Catalyzed  Chlorine Oxidation of High-Ammonia Effluents

           Municipal,  sewage-treatment  plants are frequently overloaded
and. often  produce  effluents which  contain relatively high concentrations
of • amronia (15-30  ppm N) .  Although  it was known in advance that the treat-
ment of  effluents  of this  kind would not be economical, several
oxidation  experiments  were perf ormed with high-ammonia effluents for the
purpose  of determining:   (l)  the  effect of relatively high, ammonia con-
centrations  (15-30 ppm N)  on  the elimination of COD and TOG; and (2) the
technical  feasibility of using chlorine to produce a low-ammonia effluent
for use  in the  laboratory.

           When  wastewater  containing about 15 ppm ammonia nitrogen and
having a COD of about  50 ppm  is treated with about 180 ppm of chlorine in
the dark,  the concentration of "free"  chlorine decreases rapidly, ammonia
is simultaneously  converted to chloramines, and a gradual increase in nitrate
concentration begins.  Irradiation produces a further rapid decrease in
the chlorine concentration and a rapid increase in the nitrate concentra-
tion.  These results  were  observed both at pH 5 (Experiment 20) and at pH 10
(Experiment  21).   In  these experiments, only about a 50$ decrease in COD
was produced after about 15 min. irradiation.

           The elimination  of  1 ppm of  COD requires 4.43 ppm of chlorine,
assuming complete  conversion  of the  organic matter to carbon dioxide.  If
it is  assumed that ammonia is oxidized to nitrogen gas, 1 ppm of ammonia
nitrogen requires  7.6  ppm  of  chlorine.  The oxidation of 1 ppm ammonia
nitrogen to  nitrate requires  20.3  ppm  of chlorine.

           Thus, the calculated chlorine "demand" for the effluent used
in these experiments was 114  ppm of  chlorine for the ammonia and 222 ppm
for the  COD.  However, only about  one-half (180 ppm) of the theoretical
amount of  chlorine was applied.  Since about 60% of the chlorine consumed
was theoretically  required for the COD elimination, presumably the remainder
was consumed in the oxidation of ammonia and by autodecomposition.

           Similar  results  were obtained with other effluents.   In Experiment
23, after  15 min.  in the dark followed by 15 min.  of irradiation, the
decreases  in ammonia  (down 76$) and  COD (down 30$)  accounted for 95$ of
the chlorine consumed.

          The undesirable  effect of  ammonia on the  elimination of COD is
apparent in all three  of these experiments:  in order to' eliminate 1 ppm
of COD, approximately  7.5 ppm of chlorine was required;  this was  about  170$
more than  the theoretical  amount.
                                    50

-------
          Even poorer efficiency of COD elimination was achieved in Experi-
ments 27 and 30; elimination of 1 ppm of COD required about 11 ppm of
chlorine, or 2.5 times the theoretical amount.  In these two experiments,
only about 40$ of the chlorine was used for COD elimination; the remainder
was consumed in ammonia oxidation.

          Subsequent experiments were designed for the purpose of removing
ammonia from the effluents by means of treatment with chlorine.  The objec-
tive was not to find an economical process for removing ammonia, but to
produce—in the laboratory—a low-ammonia effluent for further investigation.

          Experiment 27 showed that very poor elimination of ammonia is
achieved during a 15-min. period of chlorination in the dark.  This result
was confirmed by experiments with pure ammonia which will be discussed in
the next section.  The experiments with pure ammonia had also indicated
that ammonia elimination would be favored by avoiding large excesses of
chlorine and by operating at pH levels above 6.5.

          In Experiments 28 and 29, longer periods of chlorination in the
dark were employed.  Two samples of a high-ammonia effluent (21 ppm N) were
treated in the dark with identical quantities of chlorine while the pH was
maintained above 6.5.  In Experiment 28 5 the chlorine was added gradually
during 1 hr.; and, in Experiment 29, the chlorine was added all at once.
The gradual addition of chlorine produced a greater decrease in ammonia
concentration (an 86$ decrease compared to a 70$ decrease), and less
chlorine was required to eliminate a given amount of ammonia.  (The amount
of chlorine consumed for each ppm of ammonia eliminated was 13.7 ppm for
Experiment 28 and 14.9 ppm for Experiment 29.)  These differences, although
significant, are probably not large enough to warrant the extra effort
required to add chlorine gradually.

          In subsequent experimental work, after conditions had been estab-
lished for highly effective oxidation of organic matter in effluents, the
rate of oxidation of a low-ammonia effluent was compared with the rate of
oxidation of the same effluent when ammonia was added.  The effluent used
in Experiment 75 (Figure 22, p. 46) was low in ammonia content (1.9 ppm
ammonia nitrogen), and the rate of COD elimination (58$ after 5 min. of
irradiation and 67$ after 10 min. of irradiation) was within the range of
that observed for other low-ammonia effluents.  In Experiment 76 (Figure
25, p. 53), 23 ppm ammonia nitrogen, as ammonium chloride,  was added to
the effluent.  The inhibiting effect on the rate of COD elimination was
pronounced; instead of 58$ elimination in 5 min., only 4.5$ of the COD was
eliminated in 5 min.
                                   51

-------
          After about 12 min. in the dark, and about  6 mln. irradiation,
the chlorine concentration had been severely depleted.  Therefore, a  second
addition of chlorine—about equal to the first—was  made.  This  second
addition of chlorine evidently was sufficient to overcome the inhibiting
effefc of the ammonia, because a distinct increase  in the rate of COD  elimina-
tion was observed (Figure 25).  After a total of 13  min. irradiation, the
decrease in COD amounted to 64$.  The amount of chlorine required to  pro-
duce this decrease in COD amounted to 21.6 ppm of  chlorine for each ppm  of
COD; this was almost five times the theoretical amount  (4.43 ppm).  If
the assumption is made that the actual amount of chlorine required to
eliminate the COD was equal to the theoretical amount,  then the  oxidation
oi 1 ppm of ammonia nitrogen required 17.5 ppm of  chlorine; this was  al-
most four times the chlorine demand of 1 ppm of COD.
                                    52

-------
                                Additional
                                 Chlorine
                   10
15         20
 Time (min.)
25
30
Figure 25 - UV-Catalyzed Chlorine Oxidation of Effluent S&L-624-A Containing
               23 ppm of Added Ammonia Nitrogen at pH 5 (Experiment 76)
                                   53

-------
                REACTIONS OF AQUEOUS AMMONIA WITH CHLORINE
                                 Summary
          In water, ammonia reacts with chlorine to  form mono-, di-  and
trichloramine in various proportions depending upon  pH and  ratio  of  react ants
At pH 5, an excess of chlorine rapidly converts most of the ammonia  to
trichloramine which is relatively stable in the presence of excess chlo-
rine.  Irradiation of an ammonia-chlorine reaction mixture  rapidly acceler-
ates the conversion of trichloramine to nitrate and  other oxidation  products
of ammonia including, presumably, nitrogen gas.
                                   54

-------
The Reaction of Aqueous Ammonia with Chlorine

          In order to clarify some of the observations made during the
studies of high-ammonia effluents, a number of chlorine oxidation experi-
ments were performed using a dilute solution of ammonium chloride.

          The general experimental observations are similar to those made
with high-ammonia effluents.  When chlorine is added to ammonia in the dark,
(l) the concentration of chlorine decreases rapidly, (2) the concentration
of ammonia decreases rapidly, (3) chloramines are formed rapidly and in
varying proportions depending upon pH and reactant ratio, and (4) a slow
build-up in nitrate concentration begins.  Irradiation of an ammonia-chlo-
rine reaction mixture appears to rapidly accelerate the decomposition of
chloramines to products containing nitrogen in higher oxidation states.


          A. T. Palin has written a series of three authoritative articles
on the ammonia-chlorine interaction in water.!/ Of particular interest to
this work are his investigations concerning the products formed from
ammonia and chlorine interacting at various pH levels.  For example, his
studies at pH 5 indicate that, when chlorine  (6.0 ppm) interacts with
ammonia (0.5 ppm), the  solution contains the  following products:
                                       After 10 min.       After 2.0_hr.

 Free  chlorine                               2.7 ppm             2.9 ppm
 Trichloramine                               0.9 ppm             1.0 ppm
 Dichloramine                                3.0 ppm             0.0 ppm
 Monochloramine                              0.0 ppm             0.0 ppm
           Palin observed that monochloramine is  fairly stable  in the pres-
 ence of excess  ammonia,  but is decomposed by excess  chlorine.
                  2KH2C1 + HOC1-ปN2 + 3HC1 +
 He also observed that dichloramine will decompose to nitrogen,  HC1  and
 chlorine, but that a solution of trichloramine and excess  chlorine  is com-
 paratively stable.
                                    55

-------
          Our observations of the ammonia-chlorine reaction in the dark are
consistent with these observations, even though our  experiments were per-
formed it higher concentrations.

          In all of our ammonia-chlorine experiments, rapid and large  ini-
tial decreases in chlorine concentration were observed  (Table XV).
                                TABLE XV

    INITIAL DECREASES IN CHLORINE COHGERTRAIIOH PRODUCED  BY AMM3KIA

                                                             Observed
                    Initial             Initial          Decrease in Chlorine
                 Ammonia Goncn.      Chlorine Concn.        Concentration	
Experiment No.        (ppm N)             (ppm)	    (ppm)           (min.)

    13                12.8               148              105              2.7
    17                13.5               408              160              8.5
    26                28.8               304              167              2.3
          Evidently,  this rapid initial reaction is a result of the forma-
tion of  chloramines,  predominantly trichloramine.   Chlorine concentrations.
were determined by the  iodide-thiosulfate procedure; and, using this method,
only a small proportion of trichloramine will titrate as free chlorine.—/

          During the  rapid initial reaction, there is some oxidation of
ammonia  as  evidenced  by a rapid, but small, development of nitrate concentra-
tion in  every case.

          The initial rapid  decrease in chlorine concentration is followed
by a very slow decrease in chlorine concentration.  In Experiment 17, the
initial  decrease in chlorine concentration amounted to 160 ppm within 8.5
min.; but 4 days were required for an additional decrease of 119 ppm.

          As the second slow decrease in chlorine concentration proceeds,
there is a  parallel slow increase in nitrate concentration.
 8/  Standard Methods-Water and Wastewater,  12th Ed., 1965, p. 90, American
       Public Health Association.
                                    56

-------
          Ammonia-chloramine determinations -In all our experiments,
ammonia was determined "by the direct Nesslerization procedure.  However,
in Experiment 26, ammonia determinations after 15 min. varied markedly,
depending upon the manner in which the sample was treated.  When sodium
bisulfite was used to remove residual chlorine, only a slight decrease in
ammonia concentration was detected (from 28.8 ppm to 24.4 ppm).  When resid-
ual chlorine was removed by acidification followed by nitrogen purge, the
ammonia content had apparently decreased by 68% (to 9.1 ppm).

          We believe that the difference between the high ammonia value
obtained when one sample was treated with bisulfite and the low value
obtained when a duplicate sample was purged with nitrogen represents the
amount of ammonia present as chloramines.  Thus, at this point of the reac-
tion, the amount of ammonia present as chloramines was approximately
24.4 - 9.1 = 15.3 ppm H.  Reduction with bisulfite converted chloramines back
to ammonia, but the nitrogen purge caused ammonia nitrogen to be lost from
the solution.  This ammonia loss could occur as simple volatilization of the
chloramines or by partial hydrolysis of the relatively stable trichloramine
to mono- and dichloramines which decomposed to nitrogen (and other products).

          Effect of irradiation on the ammonia-chlorine reaction - When
an ammonia-chlorine solution is irradiated after standing in the dark for
about 15 min., there is a very rapid and extensive decrease in the chlor-
amine concentration, a rapid and substantial additional decrease in the
ammonia concentration and a rapid increase in the nitrate concentration.
In Experiment 26, the results were as shown in Table XVI.
                                TABIE XVI
            EFFECT OF IRRADIATION ON THE AMMONIA-CHLORINE REACTION
Ammonia
  (ppm N)
Chlorine
  (ppm)
Chloramines
  (ppm N)
Nitrate
  (ppm W)
                      Initial
                   Concentrations
 28.8

304

  0

  0
                  After 15 Min.
                   in the Dark
  9.1

177

 15.32'

  0.25
                 After 15 Min.
                  Irradiation
 4.0

36.8



 6.35
_a/ The difference between the high ammonia value  obtained when one sample was
     treated with bisulfite, and the  low value  obtained when a duplicate sample
     was  purged with nitrogen, provides an approximation of the chloramine
     concentration.
                                    57

-------
          The results obtained upon irradiation were similar,  even after the
ammonia-chlorine solution had been allowed to stand for 4 days in the dark
(Experiment 17, Table XVII).
                               TABLE XVII

          EFFECT OF IRRADIATION OM AN AMMONIA-CHLORINE SOLUTION
          THAT HAD BEEN ALLOWED TO STAND IN THE DARK FOR 4 DAYS

                 Initial           After 4 Days          After 30 Min.
              Concentrations       in the Dark            Irradiation
Ammonia
  (ppm H)           13.5                1.6                   0
Chlorine
  (ppm)            408                229                     0
Nitrate
  (ppm N)            0.02               4.0                   9.0
          These results indicate that chloramines are very rapidly decom-
posed by UV radiation to products other than ammonia.  Nitrate  appears to
be the major product, but other oxidation products of ammonia are  also
formed.
                                   58

-------
                  COMPARISON OF UV RADIATION SOURCES
                               Summary
         At the present time, mercury-arc lamps  are  probably the most
practical sources of W radiation for the catalytic chlorine  oxidation of
organic material in wastewater.  On the basis  of  organic  oxidation rate
produced per watt of W output, high-pressure  mercury arcs, which emit a
broad spectrum of wavelengths  (220 - 366 mp,),  are about 2.7 times more
efficient than low-pressure mercury arcs which emit almost exclusively at
one wavelength (253.7 up).
                                    59

-------
A Comparison of UV Radiation Sources

           Lewis R. Roller in his text,  ultraviolet Radiation,?/ discusses
in considerable detail the various sources  of W radiation.  Other than _
sunlight,  the  two most-useful W sources  are arcs and incandescent materials.
The most  efficient and most useful of these are the arcs.  For a number of
practical reasons, mercury arcs have  been the most-widely-used UV sources.
in our opinion, mercury-arc lamps are,  at the present time, the most prac-
tical source  of UV radiation for use  in the catalyzed chlorine oxidation
process.

           There are basically two kinds of  mercury-arc lamps:   the high-
pressure arc  and the low-pressure arc.

           The source of ultraviolet radiation  in all of our experiments
 thus far described has been a high-pressure mercury-arc lamp.  Lamps of
 this kind emit a broad spectrum of wavelengths between 220 np, and 366 np,.
 (For a description of this spectrum,  see Figure 26).  Low-pressure, mercury-
 arc lamps.emit radiation  almost exclusively at 253.7 mi.  High-pressure
 mercury arcs  generally emit much-more-intense radiation than low-pressure
 mercury arcs of about the same size.   However, the  useful life of high-
 pressure lamps is usually much shorter, and the  cost of high-pressure
 lamps is considerably greater, than that of low-pressure lamps of the same
 size.  Also,  low-pressure lamps convert electrical  energy to radiant energy
 more efficiently.  A disadvantage of the low-pressure lamps is that the
 253.7-iqjt-wavelength is not transmitted by water  or  wastewater to the ex-
 tent that longer wavelengths  are.  All these factors--intensity, wave-
 length, catalytic  efficiency, lamp cost, lamp life, and  electrical effi-
 ciency—must be considered in determining  the most  useful,  UV source  for
 the catalytic chlorine oxidation.

           The catalytic  efficiency of  radiation from low-pressure  lamps
 in promoting the  catalytic oxidation was unknown, and could only be deter-
 mined experimentally.

           The low-pressure lamp which  we used was manufactured by the
 Nester/Faust Manufacturing Corporation and is probably the most intense,
 short-wavelength  source  available commercially which will fit in the photo-
 chemical reactor.  The electrical output and electrical efficiency charac-
 teristics of this  lamp are compared  with those of the high-pressure lamp
 in Table XVIII.
                                     60

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                              TABLE XVIII

           COMPARISON  OF LABORATORY-SCALE,  MERCURY-AEG  LAMPS

                                 High-Pressure           Low-Pressure
                                    Lampg/                 Lampfr/

     Input                           450 w.                  50  w.

     UV output                        83.7 w.                40  w.

     Electrical efficiency             ฑ8.6%                 80%


~jj  These figures were obtained from Hanovia Lamp Division, Engelhard
      Hanovia,  Inc., Research Laboratory Bulletin, 5-1-59.
b/  These figures were supplied by Mr. Conman of Nester/Faust Manufacturing
      Corporation.


          Using the low-pressure lamp,  effluent oxidation  experiments were
conducted at pH 5 and at pH  10; and the same  effluent was  treated  in the
same manner using the high-pressure source.   The results of these  experi-
ments  (Experiments 55-57) are presented in  Figures  27-29.

          As expected, the rate of the  oxidation  is greater at pH  5
 (Figure  27) than at pH 10 (Figure 29);  COD  was  eliminated  about three
times  faster at PH 5 than at PH 10, and TOG was eliminated more than
 seven  times faster  at pH 5 than at pH 10.

          The  difference in  organic oxidation rate produced by the two
 sources  was also  about as expected.   A comparison of Figure 27 with  Figure
 28 shows that  the  less-intense low-pressure lamp  produces COD  elimination
 and TOC elimination at about a fivefold slower rate than the high-pressure
 lamp.

           The  efficiency of chlorine  utilization was about the same  in
 each of these  experiments:   the low-pressure lamp produced a COD elimina-
 tion of 0.122 ppm for each ppm of chlorine consumed; the high-pressure lamp
 produced a COD elimination of 0.126 ppm for each ppm of chlorine consumed.

           Although the high-pressure lamp produces a fivefold greater
 oxidation rate, its catalytic efficiency-expressed as the rate of COD
 elimination per watt of UV output-is  not  five times as great as that of
 the low-pressure lamp.  The rate of COD removal produced  by the low-pressure
 source was 0.447 ppm/min; the rate of  COD  removal  produced by the high-
 pressure source was 2.51 PPm/min.  Dividing  these  rates by UV output of

                                    61

-------
each lamp (40 w.  for the low-pressure lamp;  83.7 w. for the high-pressure
lamp) yields  a figure which represents the catalytic efficiency of COD
elimination based on radiant energy (Table XIX).
                                 TABLE XIX

                 CATALYTIC EFFICIENCY OF COD ELIMINATION
                          BASED ON RADIANT ENERGY

     Low-Pressure  Lamp                 0.0112 ppm/min/watt of UV output

     High-Pressure Lamp                0.0300 ppm/min/watt of UV output
          Thus,  the  high-pressure mercury arc produces COD elimination
more than five times faster than the  low-pressure arc, and the catalytic
efficiency of the high-pressure radiation is about 2.7 times greater than
radiation  from the  low-pressure  arc.

          Overall process  costs for both kinds of lamps have been esti-
mated based on this  information, and  are presented in a separate section
of this report.  (See "Process Costs", p. 80)
                                  62

-------
.
13
12
11
10
o 9
>- 8
CXL
LLJ
Z 7
LLJ
Q
ฃ 6
Q c
< 5
o;
4
3
2


—
-
—
-
•
-
-


-
—
1 1


























)0 220 240
1





















1 1 1











1



1







1 1 1 1
—
—
—
-
—
—
-
—
-
-
1-
1 I
260 280 300 320 340 361
                                          WAVELENGTH (millimicrons)

                Figure  26  -  Ultraviolet  Spectral Energy Distribution of the Emission from a 450-w.,
                                 Quartz,  Mercury-Vapor Lamp (Excluding the 25.6-w. Line at 366 iru)

-------
200  -

  50
                   Figure 27 - UV-Catalyzed Chlorine Oxidation of Effluent MRI-516 at i
                                   Using a Low-Pressure UV Source (Experiment 55)

-------
280
10

20         25

  Time (min.)
                                                                           30
35
                                                                                                     -28    -
                                                                                                     -24    -
                                                                                                     -  20   -
                                                                                                     -  16 "?-
                                                                                                           i
                                                                                                           CL


                                                                                                            •



                                                                                                         2U-
                                                                                                     -  8
                                                                                                     -  4
                                                                                                        0
                        14
                         12
                        10

                           I I
                            '
                         I
40
Figure 28 •• UV-Catalyzed Chlorine Oxidation or Effluent MRI-bl6 at pH 5 Using the High-Prujjure UV Source (Experiment

-------
   Lamp Inserted


         I
                                     Chlorine

                                     25


                                 Time (min.)
30
35
40
                                                                              28
                                                                              24
                                                                               20 7
                                                                                  a.
                                                                                  a.


                                                                                  i i

                                                                                  O

                                                                               16 U
                                                                               12
                                                                               8
                                         14

                                                                                         •
                                            a.


                                            ' I
                                         4 —
Figure 29 -  !JV-Catalyzed Chlorine Oxidation of  Effluent MRI-516 at pH 10


                    U;;ing a Low-Pre,       IV Sour'"-  (Experiment 57)

-------
                ULTRAVIOLET-CATALYZED CHLORINE OXIDATIOK
                           OF PURE COMPOUNDS
                                 Summary
          A brief investigation was made of the effect of UV-catalyzed
chlorine oxidation on the TOC of water containing eight pure organic com-
pounds.   The following compounds are oxidized rapidly and extensively:
phenol (61$, 8 min.), 2,4-dinitrophenol (55%, 10 min.), glycine (61$, 4 min.),
formic acid (90$, 4 min.), and o_-dinitrobenzene (65$, 10 min.).  Benzoic
acid is  also oxidized (45$, 10 min.), but not as fast as the other com-
pounds.   Acetic acid and ethanol are oxidized at a much slower rate (less
than 10$, 10 min.)
                                   67

-------
Ultraviolet-Catalyzed Chlorine Oxidation of Pure  Compounds

          In order to provide information concerning the types  of  chemical
compounds that can be oxidized by the UV-catalyzed chlorine  oxidation,  eight
pure compounds were subjected to conditions approximating those of the
effluent oxidation experiments.

          The oxidation of pure organic compounds -was  of low priority and
of secondary interest during the present research contract.   Therefore,
these experiments were designed so that they could be  performed rapidly
and with only a minimum of analytical work.

          Only the rate and extent of compound destruction were measured,
usually by TOG determinations or ultraviolet spectra analyses;  and no
attempt was made to determine the number or kinds of products formed.  In
all of these experiments,  the pH was  maintained near 5.0; this  was the  pH range
found to be optimum in the effluent oxidation studies.*

          Phenol - The rate of oxidation of phenol was followed by means
of TOG analyses (Figure 30) and appears to be quite rapid  (61$  after 8  min.
of irradiation).  The rate of TOC elimination appears  to level  off after
about 61$ of the TOC has been eliminated,  but this decrease  in  rate may
have been caused by the depletion of  chlorine.

          2,4-Dinitrophenol - Also shown in Figure 30  are  the results
of the 2,4-dinitrophenol oxidation.  The rate of  oxidation of this com-
pound is also very rapid,  as indicated by the rapid decrease in ultraviolet
absorbance at 256 mu, (practically 100$ elimination in  8 min.) and  the
fairly rapid decrease in TOC (53$ in  10 min.).

          Acetic acid '- Acetic acid is apparently not  oxidized  rapidly
under these conditions (Figure 31).  The results  of the TOC  analyses are
somewhat erratic, probably because of loss of volatile organics during
the oxygen-gas purge of the sample prior to TOC determination.   However,
the results are sufficiently conclusive to indicate that no  large  decrease
in TOC occurred during the 10-min. period of irradiation.   Chemical oxygen
demand  (COD) analyses were also made  on samples from this  reaction.  The
COD results  indicate that  only about 29$ of the COD was eliminated during the
 10-min.  period of  irradiation.  However, the results of the COD analyses
 are lower than the theoretical values because acetic acid is not completely
 oxidized by dichromate during the  COD determinations.
 *  There is no reason to believe  that pH 5 would be the optimum pH for the
      oxidation of every kind of organic compound.
                                    68

-------
          Our COD analytical prodecure calls for 50 ml. of sample.  The
 refluxing mixture of sample and acidic dichromate is concentrated by allow-
 ing 25 ml. of distillate to accumulate in a Dean Stark Trr:p.  In the COD
 determinations, the first acetic acid sample was analyzed in triplicate;
 and in one of the determinations, the distillate was submitted for TOC
 determination.  A comparison of the TOC value (10.6 mg/litor) of the
 distillate with that of the starting material (14.2 rag/liter) shows that
 37$ of the acetic acid collects in the distillate receiver during the COD
 determinations.

          The procedure of concentrating a large COD sample is recommended
 by Standard Methods^/  for dilute samples,  even though the unavoidable loss
 of volatile acids is recognized.

          In spite of the analytical difficulties, it may be concluded
 that only a relatively small fraction of the acetic acid was oxidized by
 the UV-catalyzed chlorine oxidation.

          Ethanol - The TOC data from the ethanol oxidation experiment
 (Experiment 62, Figure 31) indicate that the oxidation of ethanol does not
 proceed to a very great extent in 10 min.  (Again there appear to be
 inaccuracies in the TOC data,  probably because of loss of volatile products
 prior to the determination.)  Probably the alcohol is oxidized rapidly by
 the UV-catalyzed reaction to acetic acid (no loss in TOC) which is subse-
 quently oxidized at a much lower rate.  The  more rapid decrease of chlorine
 concentration in the ethanol oxidation (compared to the acetic acid oxida-
 tion, Experiment 61, Figure 31) is an indication that the ethanol was
 being at least partially oxidized.

          Triplicate COD determinations were made on the original ethanol
 sample; and, as in the acetic  acid determinations, a significant (18$) loss
 of volatile material from the  refluxing COD mixture was detected.

          Glycine - The oxidation of glycine is apparently quite rapid
 compared to acetic acid.  The  observed TOC decrease amounted to 61$ in 4 min.
 (Figure 32), but the rate of TOC decrease appeared to level off after it
 had decreased "by about 78$. ฅe have no explanation for the apparent tem-
porary decrease in TOC which occurred in the dark.
                                    69

-------
           Benzole acid - The oxidation of benzoic  acid proceeds  at  a
 fairly rapid rate  according  to the TOC figures:  45% in 10 min.  (Figure 33).
 This  oridation of  benzoic acid does not occur in the dark since no signi-
 fican"1" consumption of  chlorine nor decrease in TOC occurred during a
 10-min.  period of  chlorination in the dark.

          Formic acid  - Formic acid is very rapidly oxidized by the UV-cata-
 lyzed  reaction (Figure 34).  The extent of TOC decrease  amounted to 90$
within 4 min.  Practically no oxidation occurred during  an initial 10-min.
per:"od of chlorination in the dark.   It is not difficult  to explain why a
residual of TOC was not eliminated.   TOC values of  1.2-1.4 mg/liter are not
significantly different from zero;  and, therefore,  the actual amount of TOC
elimination achieved was perhaps 100$.

          ฃ-Dinitrobenzene -  The rate and  extent to which p_-dinitroben-
 zene  can be  oxidized came as  a surprise (Figure 35).  The extent of
 oxidation was followed both by UV absorbance and by TOC  determinations.
Both analytical techniques indicated that rapid and extensive oxidation
occurred upon irradiation.  Almost  all the chlorine had  been consumed
after  10 min. irradiation; and the  TOC decrease amounted to 19$ in 5 min.,
 65$ in 10 min. and 73$ in 15 min.   At the end of 16 min., practically all
the UV absorbance at 255 mi  had been eliminated. However,  the actual time
required for this elimination was probably much less than 16 min.  because
only a relatively small amount of oxidation is  required to  destroy the
aromatic ring which is  predominantly responsible for the  UV absorbance.

          In the  dark,  no significant oxidation occurred  during 10 min.;
as determined in  a separate  experiment  (Experiment  74), UV radiation in
the absence of chlorine produces no decrease  in absorbance  during 20 min.
radiation.
                                    70

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                Lamp Inserted
                   160 -
                        A

                        I Absorbance
                   140 -
                   120 -
                 i •
                 Q.
                 (
                   100  -
                    80  -
                    60
                    40  -
                    20  -
1
                                                 1
                                                       1
                                                              0.7
                                                              0.6
                                                                                                     0.5
                                                              0.4
                                                                   D
                                                                    •
                                                                   V
                                                              0.3
                                                              0.2
                                                              0.
0.0
                                                                                                               14
                                                                                                               12
                                                                        10
                                                                                                               8  I
                                                                            •
0
                                                                 20
                           10         15         20           05

                              Time (min.)                                         Time (min.)

Figure '60 - UV-Catalyzed Chlorine Oxidation of (a) Phenol (Experiment 60) and  (b) 2,4-Dinitrophenol  (Experiment 63)

-------
          Lamp Inserted
                     Lamp Inserted
    280  -
i
•
                              10
15
                                                            -
20
                                                                                                                 0
20
                  -
                                                         5          10         15

             Time (min.)                                         Time (min.)

UV-c         Chloriii-,-  Oxidation of (a) A      /Void  (Experiment 61) and (b) Ethanol  (ExperinK.it  62)

-------
 .
0
              180  r—
             160  -
                                 Lamp Inserted
Additional

 Chlorine
                             5         10         15         20         25         30         35

                                                         Time (min.)


                       Figure 32 •• UV-Catalyzed  Chlorine Oxidation of Glycine  (Experiment  68)
                                                                                                   - 14
                                                                                                      0

-------
280
                     Lamp Inserted

                                     15         20
                                      Time (min.)
25

_
--
—
•
1
14
10
8 7
U
O
6 ป-
4
2
ซ 1
30 35
     Fig'>.:;      - UV-C         Chloriii'  0; idation of B'jnzoic Acid (Experiment  69)

-------
I
                             Lamp Inserted   Additional
                                            Chlorine
                                   10
30
35
                                                                                               -  16
                                                                                               -  14
                                                                                               -  12
                                                                                               -  10
                                                                                               -  8
                                                                                               -  6
                                                                                               -  4
                                                                                               -  2
                                                                                                     a
                                                                                                     < >
                                                                                                     0
                                                                                                  0
                         15         20         25
                                Time (min.)
Figure 34 - UV-Catalyzed Chlorine  Oxidation of Formic Acid (Experiment 70)

-------



30

35        40
                            20         25
                                Time (min.)
Figure ',    • UV-Catalyzed Chi- rine Oxidation of  ^-Dinitrobenzene  (Experiment  75)

-------
          INVESTIGATION OF THE EFFECT OF ULTRAVIOLET KADI.Vn f
                       PLUS OTHER OXIDIZING AOHTTS
                                 Summar;
          A very brief study was made of the extent of organic oxidation
produced when wastewater was treated with TJV radiation plus (l) molecular
oxygen, and (2) hydrogen peroxide.  No significant redaction in TOC was
detected after oxygen had been bubbled through an irradiated reaction
mixture for 20 min.  Hydrogen peroxide produced no significant decrease in
TOC after 30 min. in the dark; irradiation of this reaction mixture for
another 30 min. produced only a slight decrease in TOC.
                                   77

-------
Investigation of the_Effect_ of Ultraviolet Radiation, Plus Other
   Oxidizing Agents

          Two reagents, oxygen and hydrogen peroxide, were investigated
for the purpose of determining whether or not the oxidizing action of
these reagents could be accelerated by UV radiation.  Both reagents are
possible intermediates in UV-catalyzed chlorine oxidation.  Therefore,
the purpose of these experiments was to provide results useful for the
interpretation of UV-catalyzed chlorine oxidation, as well as to explore
possibilities for novel UV-catalyzed oxidations.

          Because of the relatively low priority of these experiments,
no elaborate analytical studies were made.

          Treatment of wastewater with oxygen  and  UV radiation  - In
Experiment 80, pure oxygen gas was continuously bubbled through an effluent
while the reaction mixture was irradiated.  (No adjustment of pH was made
prior to, or during, the experiment.)  The results of this experiment were
compared with a similar experiment in which nitrogen gas was bubbled through
the irradiated reaction mixture.  In neither experiment was there a signi-
ficant decrease in TOC in 20 man.

          UV radiation alone had no detectable effect on the TOC content
of this effluent within a period of 45 min.  In prior experiments, UV-
catalyzed chlorine oxidation of this effluent had produced large decreases
in both TOC and COD (Experiments 75, 77,  78; Figures 19, 21, 22; pp. 43, 45, 46)

          The results of these experiments showed conclusively that (l) molec-
ular oxygen cannot be an intermediate in  the UV-catalysed chlorine oxida-
tion, and (2) UV radiation plus oxygen do not produce much organic oxida-
tion compared to UV radiation plus chlorine.

          Treatment of wastewater with hydrogen peroxide and UV radi-
tion - The same effluent used in the above series of experiments was
treated in the dark with hydrogen peroxide in excess of the amount required
to oxidize all the organic material in the effluent to C00 (Figure 36).
After 30 min. in the dark, no significant decrease in TOC was observed, ai.u
there was only a slight decrease in the hydrogen peroxide concentration.
The reaction mixture was then irradiated  for 30 min.  The irradiation pro-
duced only a very slight acceleration in  the rate of decrease in hydrogen
peroxide  concentration.  There was also a small (2Q%] decrease in TOC
during  the 30-min.  irradiation period.

          The results of this experiment  indicated that (l) hydrogen per-
 oxide cannot  be an  intermediate in the UV-catalyzed chlorine oxidation, and
 (2) hydrogen peroxide plus  UV radiation produces only a slight amount of
 effluent oxidation compared to UV radiation plus chlorine.

                                    78

-------
I
160
140
120

100
Lamp Inserted
—
A Hft
* 	 A-""" "~~'~^--A-A^ 	 	 -A__
---o 	 O-
.••ซ> O~"^^~ ™~ ""ฐvซj~~ ~~* *~- ^-^^*""" TOG
H
^Q.
,-fN 80
\J
:n

60

40

20
0
~u









1 1 1 1 1 1

0 5 10 15 20 25 30
_
-
-A 0
u—^O-^-AX
^**^"**A^ ^-*"^*^*ป-
U^^^^ "^^^^^^
"^^^^a-





_

_
i i i i i i



14

12

*E"
a_
in ^
u
O
i —

8

6

4
2
35 40 45 50 55 60
                                                           Time (min.)
           Figure 36 - Treatment  of Effluent  S&L-624 With Hydrogen  Peroxide  and  Ultraviolet  Radiation  (Experiment  81)

-------
                             PROCESS COSTS
                                 Summary
          Preliminary, process-cost estimates were made for the application
of the UV-catalyzed chlorine oxidation to the treatment of wastewater on a
large scale.  Costs of 7.2$zf to 11.1^/1,000 gal. were estimated for a plant
producing 10-million gal/day.  Because of the nature of this process, costs
would not increase significantly for plants producing 1-million gal/day.

          In determining process costs, the major factors considered were
(1) the commercial availability of UV-radiation sources, (2) the design
and efficiency of the reactor system,  (3) the transmission of UV radiation
by wastewater, and (4) the costs of chlorine, lamps, power and structure.

          The assumptions made were that a contact time of 10 min. is
required for effective organic oxidation and that the catalytic process
requires the application of  15 times more radiant energy than that required
for UV sterilization.

          Process costs could be lowered substantially if any one of the
following factors could be reduced:   (l) the amount  of radiant energ^ per
unit volume required  for effective oxidation,  (2) the contact time, and
(3) the cost of the radiation source.   The precise determination of these
factors can only be achieved by  a  study designed to  determine exactly how
much wastewater can be trea^ed effectively using each radiant energy source.
                                      80

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Process Costs

          There are four important factors to consider In estimating the
cost of UV-catalyzed chlorine oxidation •-:: a large scale.  These are (l) the
cost of chlorine, (2) the cost of the ultraviolet lamps, (5) the power cost,
and (4) the cost of structure which includes land, labor, maintenance, capital,
and interest charges.

          The cost of chlorine is the only simple factor to calculate.
Assuming that the average, highly nitrified (less than 4 ppm NH3) effluent
will possess a COD of 30 ppm, the theoretical amount of chlorine which must
be applied is 133 ppm.  The application of 135 ppm of chlorine will cost
4.10^/1,000 gal. (taking the price of chlorine as 3.65$f/lb)-ฃr/

          As will be subsequently shown,  all the other costs are directly
related to the amount of water which can  be treated by an individual W
lamp.

          Commercially  available., ultraviolet sources - Earlier in this
report, the  opinion was stated that mercury-arc  lamps are--at  the p?-esent
time--the most practical  source  of UV radiation  for this application.  Two
types  of mercury-arc  lamps were  also discussed earlier.  (Both of these
topics are discussed  in the  section  concerning UV  sources,  p.  59.)  Some
characteristics  of several,  commercially  available, UV  lamps are shown  in
Tables XX and XXI.

          These  lamps  represent  only a  small fraction of the mercury-arc
lamps  that are  commercially available  and were  selected to  provide  repre-
sentative examples.

          The  ideal lamp for this process may not be  presently available
commercially.   Most of the lamps that are available were evidently  designed
for specific uses.  Perhaps a special lamp design could be  devised  which
would provide  the  particular characteristics (e.g.,  long life, intense
output of highly effective wavelengths, etc.) which would  be  best  suited  to
this process.  Perhaps  cheaper lamps, similar to those  used for visual  il-
 lumination purposes,  could be employed with no large  offsetting decrease  in
 reaction-promoting efficiency.  However,  a consideration of the lamps de-
 scribed in Tables  XX and XXI will permit an estimate  of the lamp costs  which
 would be encountered in large-scale processes using  currently available,
mercury-arc lamps.

           funeral  design considerations  - In determining process costs,
 the most difficult factor to estimate is the amount  of water which can be
 treated with a given amount of UV energy.  Obviously, a given volume and type
 of water will require the application of a certain specific amount of UV
 energy for a certain specific time in order to achieve a pre-determined,  prod-
 uct-water quality.
                                      81

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                                TABLE XX
                COMMERCIALLY AVAILABLE, MERCURY-ARC
     Lamp
(G.  E.  Ordering              Length
 Abbreviation)     Type]?/      (in.)

    UA-11           HP          22
    UA-37           HP          52
    G64T6           LP          64
    G36T6           LP          36
    G30T8           LP          36
    H1500-A23       MP          12
    H 400-A33-1     FL           2ฃ/
                      Electrical
                          Input
                         (watts)

                           1,200
                           3,000
                              65
                              35
                              30
                           1,500
                             400
  UV
Output
(watts)
Life
(hr.)
255
782
18.5
13.7
8.8
486
22
1,000
1,000
7,500
7,500
7,500
6,000
24,000
a/  The data  in  this  table were obtained from General Electric.
b/  HP = High pressure,  LP = Low pressure, MP = Medium pressure, FL - Flood-
      lamp
c/  The arc  length of this lamp is about 2 in.; however,  the  lamp itself
      is about 8 in.  long.
                                TABLE XXI
                                  DISTRIBUTION  (IN TRAITS)
                     OF SELECTED MERCURY-ARC
SPECTRAL ENERGY
Lamp
(G. E. Ordering
Abbreviation )
UA-37
G64T6
H1500-A23
H 400-A33-1
Y
HP
J-i..K
Mr
FL
Far UV
'/ (220-280 mti)
250(22$)
18(90$)
189(26$)
0(0$)
Middle UV
(280-320 mu)
279(25$)
0.4(2$)
157(22$)
1.5(2$)
Near UV
(320-400 nu)
252(22$)
0.3(1.5$)
140(20$)
20.5(26$)
Visible
(400-700 nu)
347(31$)
1.3(6.5$)
227(32$)
55.7(72$)
 T/The data in this table  were obtained from General Electric.
 b/  HP = High pressure,  LP  = Low pressure,  MP = Medium pressure, FL = Floodlamp

-------
                               TABLE XXII
                 REPLACEMENT COSTS OF MERCURY-ARC
     Lamp
(G.  E. Ordering
 Abbreviation)

   UA-11
   UA-37
   G64T6
   G36T6
   G30T8
   H1500-A23
   H 400-A33-1
Lamp
Cost*?/
Daily /
Costฃ/
                                            2.33
                                            3.68
                                            0.0448
                                            0.0400
                                            0.0112
                                            0.450
                                            0.0124
Daily Cost of 100
Watts of UV Output
      ($)	

     0.914
     0.470
     0.242
     0.292
     0.128
     0.0927
     0.0564
a/  The data in this table were obtained from General Electric.
b/  These figures are the replacement costs of the  individual lamps if the
      lamps are purchased in large quantities.
ฃ/  The daily cost is the replacement cost divided by the lamp life in
      days.
          The General Electric brochure on germicidal lamps (TP-122) states
that a device, such as the one shown in Figure 37, "will provide 90$. dis-
infection (with a 100$ factor of safety) of drinkable water, transmitting
2537 A effectively to a depth of at least 5 in., if these rates of flow
are not exceeded:  (lamp) G-30T8, 500 gallons per hr."  In this apparatus,
the amount of water treated at one time is 36 x 5 x 8 = 1440 in  =6.24 gal.
At a flow rate of 500 gal/hr, the average "contact time" is 0.748 min.,
and the UV energy applied is 1.06 w. -min/ gal.*

          Our studies have Indicated that a contact time of approximately
10 min. will be required for substantial elimination of COD and TOC.  A
10-min. contact time in a reactor such as the one described in Figure 37
would reduce the flow rate to 37.4 gal/hr, and the UV energy applied would
be 14.1 w. -min/ gal.  Therefore, in our cost estimation, we have assumed
that effective organic removal can be achieved by the application of 15 w.-
min/gal .
*
   The G-30T8 lamp emits 8.8 w. of UV energy (8.8 x 0.748) -r 6.64 = 1.06 w.
     min/gal .
                                     83

-------
              ALZAK
            ALUMINUM
            REFLECTOR
                                                           LET
Figure 37 - Suggested Dimensions and Ratings of a Small, Gravity-Type
                           Water Disinfector*
This is the simplest  of  four designs proposed by General Electric
     their brochure on Germicidal Lamps (TP-122).   The designations
     T8 and G30T8  refer  to lamps produced by GE.
                                  84

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          Transmission of UV radiation by wastewater - Another factor which
will influence the amount of water which can "be treated at one time is the
UV transmission characteristics of the water.  The General Electric Com-
pany has used the term "Effective depth of penetration" (EDP) which is the
depth at which 90$> of the UV energy has been absorbed.  This value is simple
to determine for a single wavelength such as that used in germicidal applica-
tions, and it varies from 2 to 5 in. for a typical wastewater.*  However,
for high-pressure, mercury-arc irradiation the EDP is more difficult to
determine because of the spectrum of wavelengths emitted by these lamps.
Since most of the energy emitted by high-pressure lamps is of longer wave-
length, a considerable increase in EDP would be expected.  For example,
examination of the UV spectrum of a typical wastewater shows that the EDP
at 366 n^, (the most prominent wavelength emitted from a high-pressure
mercury arc) is at least six times as great as the EDP at 253.7 m^.  Further-
more, our studies have shown that, as the UV-catalyzed chlorine oxidation
proceeds, the UV transmission of the wastewater increases greatly (see
Experimental, p.  118).

          In germicidal operations, the EDP cannot be exceeded without
decreasing the effectiveness of the process.  However, the UV-catalyzed
oxidation process is not subject to this limitation.  In germicidal opera-
tions, it is required that no portion of the water receive less than a
sterilizing dose  of radiation.  However, in the oxidation process, even the
smallest amount of UV energy will contribute to the extent of oxidation.
In germicidal operations, UV energy must be wasted to insure sterilization;
in the oxidation  process, maximum utilization of UV energy is desired.
Thus, for maximum efficiency, the oxidation process must treat water at
depths which substantially exceed the EDP  for sterilization  applications.

          Cost of lamps, power  and  structure  - The above discussion indicates
that many factors must be considered  in selecting the most effective, UV
source and reactor design for  large-scale  water  treatment.   However, based
upon the assumption that 15 w.-min/gal  of  UV energy will be  required for
the catalyzed chlorine oxidation, some  estimates of the cost of presently
available lamps,  power, and  structure  can  be made.
    Personal communication,  Dr.  R.  B.  Dean,  Cincinnati  Water Research
      Laboratory.
                                      85

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          Lamp costs - The UA-37 lamp  (Tables XX and XXI ) is representative
of high-pressure mercury arcs.  The  782-w. UV output of this lamp would
permit the treatment of 52.2 gal/min., or 75,100 gal/day.  Considering the
daily lamp replacement cost of  $3.68 (Table XXI), the lamp cost would be
4.
          Our laboratory studies  have  shown that the  catalytic efficiency
of high-pressure lamps is 2.7 times  greater than that of the low-pressure
lamps (Table XIX ).  Therefore,  for performance  comparable to that of the
high-pressure lamps (which are  assumed to  be  capable  of operating effectively
with an application of 15.0 w . -min/gal ) , the  amount of energy required from
low-pressure lamps would have to  be  40.0 w. -min/gal.

          The G64T6 lamp (Tables  XX  and XXI )  is typical of low-pressure
mercury arcs.  This lamp emits  only  18.5 w. of  UV  energy which would per-
mit the treatment of only 0.46  gal/min, or 665  gal/ day.  Considering the
daily replacement cost (Table XXI ),  the lamp  cost  would amount to 6.74^/1,000
gal.

          The relatively high costs  of both types  of  these lamps suggest
that other radiation sources be considered.   Since the relative efficiency
of longer wavelengths is not known,  perhaps cheaper lamps which provide
irradiation in the near ultraviolet  (340-400  mj, ) or short -wavelength visible
(400-450 ma) might be developed especially for  this application.

          Two other types of mercury-arc lamps  are described in Tables XX
through XXII.  One of these is  a  1,500 w.  medium-pressure lamp (G. E.
ordering abbreviation H1500-A23)  and the other  is  a 400 w. mercury-arc lamp
for floodlighting applications  (G. E.  ordering  abbreviation H400-A33-1).
These lamps have been designed  to provide  exceptionally long lifetimes.  The
longer life of these lamps plus the  fact that they are marketed in large
vo-unie, results in significantly  lower daily  costs per 100 w. of UV output
(Tacle XXII).
          Power costs - The high-pressure  lamp  (UA-37) requires 3,000 w.
of input electrical energy.  The  daily cost of  this energy would be 57. 6^/
lamp, assuming that power costs 0.80jf/kw-hr.  Since our calculations
indicate that each lamp will treat 75,100  gal/day, power cost would be
0.77^/1,000 gal. of water treated.

          The low-pressure lamp (G64T6) requires only 65 w. of input elec-
trical energy, or a daily cost  per lamp of 1.25^.  Assuming that each lamp
treats 1,400 gal/day, the power cost would be 0.89^/1,000 gal.

          On a similar basis, power  cuts for  the medium-pressure lamp
(H1500-A23) would be 0.62^/1,000  gal.;  for the  floodlamp (H400-A33-1), 0.35yf/
1,000 gal.

                                     86

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          Structure costs - If each high-pressure lamp (UA-37) will treat
75,100 gal. of water per day, then 133 lamps are required for a plant proc-
essing 10-million gal/day.  The size of this plant can "be estimated at 2,310
sq. ft., based on the length of the lamps and by assuming that the total
width required for the channel is 4 ft.  At $10/sq. ft., the estimated cost of
structure would be $23,100.  Straight-line depreciation (20 years) places
the daily contribution of structure cost at $3.21.  Maintenance (at 11$ of
structure cost) is estimated at 36^/day.  The daily labor cost (one man,
24 hr/day) of $120/day would be the most significant factor in structure
cost.

          Thus, for the high-pressure lamps, the total cost of structure,
land, maintenance, labor, capital and interest is estimated at $125/day, or
1.25^/1,000 gal.

          Structure costs are considerably higher for the low-pressure
lamps because of the greater number of lamps required.  Each low-pressure
lamp (G64T6) will presumably treat 665 gal. of water per day.  This means
that 15,000 lamps are required for a 10-million gal/day plant.  In order
to hold the size of the plant to a reasonable figure, we have assumed that
five lamps can be used in each unit cell.  We have further assumed that
no loss of radiant energy is produced by this grouping of the lamps.
Making the same assumptions as were made for the high-pressure lamps, a
plant size of 30,600 sq. ft. and costing $306,000 is obtained.  Straight-
line depreciation  (20 years) leads to a daily structure cost of $42.50.
Maintenance would be $4.67, and labor  (two men, 24 hr/day) is estimated at
$240/day.

          Thus, for the  low-pressure lamps, the total cost of structure, land,
labor, capital, and interest is estimated at $290/day, or 2.900/1,000 gal.

          Structure costs cannot be estimated on a similar basis  for the
medium-pressure lamp or the floodlamp because of their considerably shorter
arc-lengths.  However, using the above  estimates and assuming that structure
costs will be inversely proportional to the amount of water treated per
lamp, the  structure cost  for the medium-pressure lamp would be 1.50^/1,000 gal.,
structure  cost for the floodlamp would  be 2.70^/1,000 gal.

          Total process  costs  - Total  estimated process costs are shown in
Table XXIII.  Process costs for the high-pressure  and low-pressure lamps are
approximately the  same,  and there  is an obvious  "trade-off" between these two
kinds of lamps; the low-pressure lamps  are  cheaper, but require higher
structure  costs.

          Total process  costs  for  the medium-pressure  (H1500-A23) and flood-
lamp  (H400-A33-1)  are significantly lower because  of the lower cost of
producing ultraviolet energy using these lamps.

                                     87

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          Each  of these estimated total process costs  could be lowered
considerably  if any one of the following factors could be reduced:  (l) the
amount of radiant energy per unit volume required for  effective oxidation,
(2) the contact time,  and (3) the cost of the radiation  source.  The precise
determination of these factors can only be achieved by a study designed to
determine exactly how  much wastewater can be treated effectively using each
radiant energy  source.
                                TABLE XXIII

                ESTIMATED PROCESS COSTSg/ (CEHTS/1,000 GAL)

               High-Pressure    Low-Pressure     Medium-Pressure
                  Lamps	       Lamps             Lamps	     Floodlamp

Chlorine          4.10              4.10            4.10                4.10
Lamps             4.90              3.20            0.97                0.59
Power             0.77              0.89            0.62                0.36
Structure         1.25              2.90            1.50                2.70

                 11.02             11.09            7.19                7.75
a/  Costs  were calculated assuming:  (l) that a contact  time of 10 min.
      was  required; (2) that the ultraviolet energy required is 15.0 w.-min/gal,
      for  the high-pressure lamps and 40.0 w.-min/gal.  for the low-pressure
      lamps; and (3) that the low-pressure lamps could be operated in clusters
      of five with no significant loss in radiant energy.
                                     88

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                              EXPERIMENTAL
Photochemical Reactor

          All of the effluent oxidation experiments were performed in the
photochemical reactor shown in Figure 38.  The reactor consisted of a
typical laboratory apparatus for the investigation of UV-catalyzed reac-
tions and was suitably equipped to permit thermal control, rapid sampling,
continuous monitoring of pH and the addition of aqueous alkali to control
pH as the oxidation proceeded.  The reactor vessel was a 5-liter, four-
necked flask equipped with a quartz immersion well.  The immersion well
(Hanovia Lamp Division, Engelhard Hanovia, Inc.) contained the ultraviolet
source, and was equipped with an outer jacket through which cooling water
was circulated. This well was located in the large center neck of the flask.

          A combination pH electrode was placed in one of the side-necks.
Into another side-neck was placed a thermometer, thermocouple well, and a
glass tube which  led to a syringe-type sampling device (Manostat Corpora-
tion).  The third side-neck was equipped with a 500-ml., pressure-equalizing,
addition funnel.

          The contents of the flask were stirred by a magnetic stirrer.
Temperature was controlled by a "Gardsman" controller  (West Instrument
Corporation) which was activated by the thermocouple.  The controller
activated an off-on  switch which regulated the flow of cooling water to
the immersion well.  A regulator was used to maintain the pressure of the
cooling water at  about 5 psi.  If additional cooling was required, the
cooling water was passed through a  coil  of  aluminum tubing immersed  in
ice-water.  Reactions "in the dark" were performed by wrapping the reactor
in aluminum, foil.
 Ultraviolet  Radiation Sources

           The  ultraviolet source for almost  all the oxidation experiments
 was  a 450-w.,  high-pressure,mercury-vapor lamp powered by  a  285-v. trans-
 former (radiated energy,  175.8 w.).   The  lamp  and transformer are products
 of the Hanovia Lamp Division,  Engelhard Hanovia, Inc.  The spectral output
 of this lamp is typical of high-pressure, mercury-arc  lamps  and  is shown in
 detail in Table XXIV  and graphically in  Figure 26  (p. 63).
                                    89

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.re  38 - r.        for
Shlori .   Qxic at i
                          90

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                           TABLE XXIV
         SPECTRAL-ENERGY DISTRIBUTION OF HIGH-PRESSURE,
MERCURY-ABC LAMP
Mercury Lines
(millimicrons)
1367.3 (infrared)
1128 „ 7
1014.0
578.0 (yellow)
546.1 (green)
435.8 (blue)
404.5 (violet)
366.0 (UV)
334.1
313.0
302.5
296.7
289.4
280.4
275.3
270.0
265 . 2
257.1
253.7 (reversed)*
248.2
240 oO
238.0
236.0
232.0
222 4
Total watts

Radiated Energy
(watts)
2.6
3.3
10.5
20.0
24.5
20.2
11.0
25.6
2.4
13.2
7.2
4.3
1.6
2.4
0.7
1.0
4.0
1.5
5.8
2.3
1.9
2.3
2.3
1.5
3.7
175.8
253.7 line is reversed in high-pressure lamps
                                91

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          An alternate ultraviolet  source was a low-pressure, mercury-arc
lamp manufactured by Nester/Faust Manufacturing Corporation and specially
modified to fit in our reactor.  This  lamp was selected because it is prob-
ably the most intense, short-wavelength source available commercially which
would fit within the immersion well.   The electrical output and electrical
efficiency characteristics  of  this  lamp are  compared with those of the high-
pressure lamp in Table XVIII (p. 61).   Data  supplied by the manufacturer
indicated that 96$ of the UV output of this  lamp  is between 245 n^ and 260 iqj,
Analytical Methods

          All analytical determinations were performed as described in
Standard Methods.i^/  Total organic  carbon  (TOC) determinations were per-
formed at the Cincinnati Water Research Laboratory by means of a Beckman
carbonaceous analyser; the brucine method was used for nitrate determina-
tions; ammonia was determined by direct Nesslerization; chlorine was deter-
mined using the iodometric procedure.  All  analytical samples were imme-
diately acidified to pH 1 with concentrated sulfuric acid in order to
stabilise the samples for COD and TOC analyses.

          The acidified (pH l) samples for  COD analysis were dechlorinated
by purging the sample with nitrogen  gas until no chlorine could be detected
by means cf starch-iodide paper.  The removal of chlorine by this method
is facilitated by low pH values  (Figure 39), and this step usually required
about 15-20 nin.  Longer periods of  time were required when the effluent
contained more than 4 ppm of ammonia.  The  TOC sample was dechlorinated
with excess, solid, sodium bisulfite, and was similarly acidified.
Sources of Waste-water

          The primary sources of wastewater x^ere local, municipal, sewage-
treatment plants of the extended aeration type.  Another source of waste-
wator was an experimental sewage-treatment plant operated by the Smith &
Loveless Corporation, Lenexa, Kansas.  This plant is also of the extended
aeration type and treats sewage from the city of Lenexa, Kansas.  Apparently,
the design of this plant is to be patented, and the company cannot release
details of the process.  The Smith & Loveless plant proved to be a very
reiiable source of highly nitrified effluent.
                                   92

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200
                 Figure 39 -
         Time (min.)

Effect of pH or. the Rate of Chlorine Removal
 From an Aqueous Solution During Nitrogen-
              Gas Purge


-------
          Since ammonia concentrations above 3-4 ppm could not be oxidized
economically, effluents containing more than 4 ppm of ammonia nitrogen were
further nitrified by means of the laboratory-scale, activated-sludge appa-
ratus. (See p.  96.)

          On arrival, the effluents were filtered through a cylindrical plug
(1-1/4 in. diameter x 4 in.) of Pyrex, glass-wool, filtering fiber.  This
procedure removed 99% or more of the total suspended matter in the effluents.
The filtered effluents were stored in a cold, room (9ฐC) and were ordinarily
used the same week that they were obtained.  Each 5-gal. sample of effluent
was filtered and analyzed on arrival for COD, TOG, ammonia, nitrate and (occa-
sionally)  nitrite.  The COD and TOC determinations were repeated immediately
before the oxidation experiments.

          The Zinzer plant - The equipment used in this plant was manu-
factured by the Smith & Loveless Corporation.  It has a capacity of 17,000
gal/day with a BOD loading of 34 Ib/day.  At the time it was sampled, this
plant was loaded at a rate of 7,200 gal/day, and 15.3 Ib. of BOD/day, during
the summer months.  During the remainder of the year, the load is increased
to 15,855 gal/day and 38.38 Ib. of BOD/day.  The increased loading is
caused by operation of an elementary school.

          Some characteristics of the Zinzer plant are presented in Table
XXV.
                               TABLE XXV

                  CHABACTERISTICS OF THE ZIMZER PLANT

Jfodel No. (Smith & Loveless)                                  12C17
Aeration tank
  Capacity  (gal.)                                             17,000
  Normal BOD capacity (lb/day)2/                                  34
Blowers
  Recommended capacity (cfm)                                      72
Settling tank
  Total capacity (gal.)                                        3,949
  Overflow  rate (gal/sq. ft./day)                                135
 a/ Based on 15 Ib.  of 5-day BOD/1,000 cu. ft. of aeration tank capacity.
                                     94

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          The Nance plant - This plant is of the extended aeration type and
was built in place.  Only one of the two aeration tanks is presently in
operation.  The influent is aerated for 24 hr. at 1-2 ppm dissolved oxy-
gen and passes to the settling tank where it is retained for 4 hr.  Other
characteristics of this plant are presented in Table XXVI.
                                TAILS XXVI

                   CHARACTERISTICS OF THE NANCE PLANT

Aeration Tanks
  Capacity, Each (gal.)                                    40,250
  Retention Time (hr0)                                         24
Settling Tanks (2)
  Capacity, Each (gal.)                                     6,700
  Retention Time (hr.)                                          4
Estimated BOD Load (ib/day)                                    68
          The Randolph Corners plant - This plant serves 79 homes repre-
senting an inflow of 22,120 gal/day.  The plant is very similar to the
Zinzer plant, except that there are two units of 17,500-gal. capacity each.

          The Gracemore plant - This plant uses a relatively new "Oxigest"
design by Smith & Loveless.  The process is more sophisticated than simple
"Extended Aeration"  and is a modification of conventional activated-
sludge treatment known as "Contact Stabilization."  A feature of this proc-
ess is a re-aeration of the activated sludge.

          The Gracemore plant is much larger than the other municipal
sewage-treatment plants.  During normal dry weather, the plant receives
195,300 gal/day.  This figure increases to 500,000 gal/day during wet
weather.  The flow is divided, about half going to the Model R Oxigest
facility and half going to an Imhoff-Tank, Trickling Filter.  The Oxigest
facility has a design, BOD-load capacity of 425 Ib/day.  During wet weather,
the design flow is exceeded substantially.
                                   95

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 Laboratory-Scale, Sewage-Treatment Apparatus

          The apparatus was similar to the one described by Ludzackiz/, and it
 incorporated most of the features of similar apparatus at the Cincinnati
 Water Research Laboratories (personal communications, E. F. Earth and C. E.
 Ehines).  A photograph of the apparatus is presented in Figure 40.

          The aerator compartment consists of a 9-liter, Pyrex, glass bottle
 with the bottom cut off and a 3/4-in. hole drilled in the side.  The vol-
 ume of this compartment, when filled to the overflow point, is 7.6 liters.
 The aerator compartment was placed in a specially designed hood equipped
 with Plexiglas doors and an exhaust fan which conducts air to an adjoining
 exhaust hood.  Influent to the aerator flows from the bottom of a 5-gal.
 jug situated on top of the hood.  Effluent from the aerator flows to a
 5-gal. plastic carboy located under the hood.

          The starting material used in this apparatus consisted of effluent
 obtained from a municipal plant (Gracemore).  Control over the rate at
which this material flows  into the aerator compartment is maintained by an
 air bleed, through a needle valve (Nupro 4 M Fine Metering Valve), into the
reservoir.  The rate^ of flow was allowed to vary from about 4 to 8 liters/day.
Effluent Analyses

          A summary of the characteristics of effluents obtained from var-
ious sewage treatment plants is presented in Table XXVII.
General Procedure

          Filtered effluent (4.0 liters) was placed in the reactor, and
samples of the untreated effluent were analyzed for total organic carbon
(TOG), chemical oxygen demand (COD), ammonia and nitrate.

          The pH of the effluent was adjusted to the desired value using
concentrated sulfuric acid or 40$ aqueous sodium hydroxide.  Chlorine water
was placed in the addition funnel, and an aliquot was taken for analysis.
The volume of chlorine water in the funnel was adjusted to provide the
desired initial chlorine concentration in the reactor.  The chlorine water
was added rapidly to the reactor, and the pH was readjusted—if necessary
                                    96

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Figure 40 - Laboratory-Scale, Sewage-Treatment Apparatus

-------
Effluent*
 z-i
                              TABIE XXVII

               AMLYSES OF EFFEUEHTS USED IN THIS STUDY

                  Amonia (ppm gj.          Nitrate (ppm ง]
                       22.06
G-l
G-2
G-3
G-4
G-5
RC-2
G-5 A
RC-3
0-6
S&L-l
S&L-3
S&L-5
S&L-6
G-59C
MRI-428
MRI-512
mi-516
G-5 28
MRI-61
S&L-619
S&L-625
3.8 (avg.
13.9 (avg.
30.5
30.2
"1 f* Q
|_Q • 53
23.7, 25.7
20
21.8
32.0
1.8 (avg.
2.1
)
)







.)

0.9 (avg.)
1.6
14.38, 14.80
2.2
2.52
1.33
19.98
4.33
22.6, 23.0
1.94, 2.60









                                                7.8
                                                       (avg.)
                                                 11.0 (avg.)
                                                 11.5
                                                 10.6 (avg.)
                                                 13.4
                                                  0.05
                                                 35.8
                                                  3.08
                                              11.50,  10.38
                                                  0.15
                                                 24.00
                                               0.15,  0.15
                                               3.74,  3.60
                                                                    29.4 (avg.)
                                                                    49.7
                                                                   35    (avg..
                                                                   24     avg.
                                                                   22.0  (avg.)
                                                              18-9, 21.5
                                                              51.65, 43.43
                                                              31.2, 3S.3
                                                              35.76, 34.54
                                                              29.51, 29.66
                                                                   207.3
                                                                   23.74
                                                              26.53, 24.73
                                                              31.34, 31.41
   The first code  letter,  or letters,  refer to the effluent source (G = Grace-
     more subdivision sewage treatment plant; Z = the Zinzer plant, N =
     the Nance plant;  EC = Randolph Corners plant; S&L <= Smith & loveless
     Corporation,  experimental plant,  Lenexa, Kansas; VSH. = effluent from
     laboratory- scale, sewage -treatment apparatus at Midwest Research Insti-
     tute).  The number after the code letter refers either to the sample
     number or to  the date obtained (for example, 59 represents May 9th).
Usually, the  chlorine-treated effluent was allowed to  stand in the dark
for about  10  min.   During this time, the chlorine concentration was deter
mined at various intervals; at the end of this period, samples were with-
drawn for  COD and TOC analyses.
                                     98

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          The ultraviolet lamp, which was omitting at maximum intensity,
was then placed within the immersion well.  Samples for COD and TOG analyses
were taken at about 5-min. intervals  and were treated as before.  The
chlorine concentration was determined frequently during the irradiation
period.  In almost all the experiments, the pH of the reaction mixture was
adjusted from time to time using  40% aqueous sodium hydroxide.

          The acidified  (pH  l)  samples for COD analyses were dechlorinated
"by purging the sample with nitrogen gas  until no chlorine could be detected
by means of starch-iodide paper.   The removal of chlorine by this method
is facilitated by  low pH values,  and this step usually required 15-20 min.
(longer periods of time  were required when the effluent contained more
than 4-5 ppm of ammonia).  The  TOC sample was taken separately, dechlorin-
ated with excess solid  sodium bisulfite, and similarly acidified.
 Effect  of Ultraviolet Radiation on Chlorine Water
          The  reactor was  charged with tap water and  chlorine water to
provide  4,300  ml.  of water containing about 200 ppm C12-  The pH was
adjusted to  the  desired level (with concentrated HC1  or  10$ NaOH), the
chlorine concentration was determined, and the UV lamp was turned on.  Tempera-
ture  of  the  contents of the flask was maintained by passing ice-water
through  the  cooling jacket of the immersion well.  The rates of decomposi-
tion  at  pH 5 and pH 10 are shown in Figure 20 (p. 44).


First Series of Wastewater Oxidation Experiments (Experiments  5-8)

          The  first series of six experiments was designed to  investigate
two  levels of  pH (5 and 10).  Control experiments were run to  determine the
effect of chlorine in the dark and the effect of UV radiation  in  the
 absence  of chlorine.  The experimental design is shown in Table I (p.  5).

           In this series of experiments, the UV lamp was placed in the
reactor  and  turned on at the time indicated.  In experiments to be per-
formed in the  dark, the reactor was covered with aluminum foil; and, of
 course,  the  lamp remained off.

           The  effluent used in the first series of experiments was obtained
 from the Gracemore sewage treatment plant  (G-l).  It was treated  with  sul-
 fur ic acid  (4 ml/gal.) at the point of collection.

           The analytical results for  chlorine concentration, TOC  and COD
 (plotted vs. time) are shown in Figures 3-8 (pp. 12-17).

                                    99

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          In Experiments  3 and 4 (Figures  3 and 4), the final TOG and COD
samples were taken at 27  and at 20 min., respectively.  However, the chlo-
rine was gone  after about 17 min. and 8 min., respectively.  Because of
this inopportune sampling time, oxidation  rates at pH 5 and pH 10 could not
validly be  compared with  these data.
Second. Series of Effluent Oxidation Experiments  (Experiments 59-47)

           The effluent used in this series was obtained from the Smith &
Loveless,experimental,sewage-treatment plant  (S&L-5).  The experimental
design is  presented in Table VI (p. 20).  The GOD and TCC  samples were taken
simultaneously; the samples were acidified (pH l) with sulfuric acid and then
purged with nitrogen until no chlorine could  be  detected using starch-
iodide paper.  Part of each sample was sent to Cincinnati for TOG deter-
mination,  and the remainder was analyzed for  COD.
at ion

 Time
(min.)

    0
    0
  2.2
  5.0
  9.5
  9.9
 21.2
 26.2
 31.2
 36.2
           Experiment 59:  High chlorine (175 ppm), pH 6.5, 15 min. irradi-
   Sample

    39A
 C12 added*
    39B
Lamp inserted
    39C
Chlorine
  (ppn)
  171
  119.7
  166.0
  185.5
   43.5,
   12.0
    6.9
                                      COD
TOG
            20.7,  20.9
10.2
            13.6,  14.7
             9.1,  11.8
 8.8
                                                                    21.5
*   290 ml.  chlorine water (containing 2,530 ppm chlorine).
                                    100

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          Experiment  40:   Low  chlorine  (102 ppm),  pH 8.5, 10 min. irradia-
tion
 Time
(min.)

  0
  0
 3.9
 6.5
 9.2
10.0
10.5
15.5
20.5
                      Chlorine
              COD
               TOG
  Sample
    40A
  C12 added*
   40B
Lamp Inserted

   40C
102
 93.1
 98.4
 93.9
 21.8
  6.9
          24.1,  23.3
          16.6, 13.7
12.9
               9.6
                                                  6.0
21.0
    175 ml.  chlorine water (containing 2,430 ppm chlorine).
           Experiment 41:  No chlorine, 10 and 15 min. irradiation
Time
(min. )
0
10.4
15.8

Sample
Lamp inserted
41A
41B

pH
7.5
7.4
7.4
Experiment 42: Low chlorine (102 ppm),
Time
(min. )
0
0
2.3
5.0
9.2
9.8
10.6
15.7
20.6
25.6

Sample
42A
Gig added*
—
--
—
42B
Lamp inserted
—
—
42C
Chlorine
(ppm)
__
102
92.7
99.6
98.5
—
—
25.9
2.3
0.0
COD TOC
(ppm) (ppm)
20.4, 21.2 "9.6
24.8, 18.1 8.6
18.1 7.8
pH 8.5, 15 min. irradiation
COD TOC
(ppm.) ( ppm )
19.7, 18.9 12.4
—
— —
—
—
19.4, 18.1 11.4
—
--
__
11.9, 11.9 7.8
                                     101

-------
ฃ
Time
(min.)
0
0
2.1
5.1
9.2
10.2
12.9
17.9
22.9

Sample
43A
Clg added*
—
—
__
43B
Lamp inserted
__
43C
Chlorine COD
(ppml (ppgl
20.6, 17.8
178.0
160.3
171.3
171.7
14.0, 17.8
—
71.0
10.3 8.7, 8.4
	 \
TOC
(PPrc)
8.6
™ ™
™" ^
~"—
— —
8.2
ป
— -
6.0
   325 ml. chlorine water (containing 2,370 ppm chlorine).


          Experiment 44:  High chlorine (175 ppm), PH 6.5,  05 min. irradiation

 Time                                     Chlorine       COD        TOC
(min.)                Sample                (ppm)        (PPm)       (PF1)

  0                     444                   ~        17.5, 20.9    28.0
  0                   C12 added*            178
 1.5                     "                  170.2
 5.2                     -                  176.3
 9>2                     —                  176.9
 9]Q                    44B                   —        18.2, 18.7     8.4
10.8                Lamp inserted
15.8                     —                   60.7
20.8                     "                     6.2
25.8                    44C            '         0.6        6.4, 8.0      4.6
*  325 ml. chlorine water (containing 2,370 ppm chlorine).
                                     102

-------
          Experiment 45;  Low chlorine (102 ppm),  pH 6.5,  15 min. irradiation
Time
(min. )
0
0
2.1
5.3
9.0
9.8
10.2
16.5
20.1
25.2

Sample
45A
C12 added*
--
—
—
45 B
Lamp inserted
--
--
45C
Chloric COD
(ppm) (ppm)
22.8, 21.8
104
93.9
97.0
97.0
18.7, 19.9
__
5.7
0.2
0.0 4.6, 8.7
\
TOG
(ppm)
9.0
--
— ~
--
--
9.4
--
--
--
9.8
*  190 ml. chlorine water  (containing  2,290 ppm  chlorine).
          Experiment  46:   Low chlorine  (102 ppm), pH  6.5, 10 min. irradiation

                                                            COD      TOG
                                                            (pffli)    iฃpml

                                                            22.2     7.8
Time
(min.)
0
0
2.5
5.2
7.9
8.8
10.2
10.6
11.0
15.7

Sample
46A
C12 added*
—
—
—
—
46B
Lamp inserted
—
—

pH
7.7
--
-~
—
6.4
—
--
--
6.3
_„
Chlorine
(ppm)
— —
102
88.9
91.6
--
95.0
— —
— —
— ซ.
28.6
                                                          15.2,  14.4   8.4



                     46C           6.2             0.6     7.1,  5.6   6.2


    200 ml. chlorine water  (containing 2,136 ppm chlorine).
                                     103

-------
          Experiment 47;  High chlorine, (175 ppm), pH 8.5,  10 min.  irradiation
Time
(min.)
0
0
2.4
4.6
4.9
8.9
9.8
10.1
10.4
15.2
18.8
20.4
Sample
47A
C12 added*
—
—
—
47B
—
Lamp inserted
—
—
47C
                             pH
                             7.7
                              8.5
                              8.85
                              8.25
Chlorine
  (ppm)
   174
   162.3

   168.3
   168.9
                                              45.8
 COD
(PPn)

 20.2
                                                       12.4, 13.7
                                               2.1      8.2, 9.0
 TOG
(ppm)

 10.0
                             7.2
                             6.8
    345  ml.  chlorine water (containing 2,191 ppm chlorine).
Third Series of Effluent Oxidation Experiments  (Experiments 48-50, 52-54,
   and 77 and 78)

           A major difference in procedure was followed in this series; TOG
and COD samples were taken separately.  The TOC samples  (30 ml.) were imme-
.diately treated with excess sodium bisulfite and acidified with concentrated
sulfuric acid (4 drops/30 ml. sample) to pH 1.   The COD  sample (120 ml.)
was acidified, as before, to pH 1 and purged with a stream of nitrogen until
no chlorine could be detected using starch-iodide paper. In a number of
these experiments, a second addition of chlorine approximately equal to the
first was made after most of the original chlorine had been consumed.
                                     104

-------
addition
          Experiment 48:  pH 5.0, 26 min. irradiation, two-stage chlorine
Time
(min.)
0
0
0

2.2
3.6
5.1
9.6
9.7
10.2
11.2
15.6
15.9
16.1
16.9
20.9
21.0
21.5
25.8
26.5
27.4
29.2
29 .-5
32.1
37.4
37.4

Sample
48A*
48-1*
C10 added**
2
--
—
--
—
48-2
48B
Lamp inserted
—
.
48-3
48C
—
48-4
48D
48-5
48E
C12 added**
— —
—
—
48F
48-6
                             pH
                              3.6
                              2.7
                              9.0
                              3.05
                              2.2
                                       Chlorine
127
112.8

119.1
118.5
                                          50.2
< 0.5


91.6

51.0

16.6
             COD
            (PPฐ0

            19.3
                                                   15.0,  15.0
                                                   12.2,  13.5
                                                   13.5,  10.7

                                                    8.8,  10.7
                                                       4.2***
 TOC
(ppฐ0
                                                                  7.8
                                                                   7.0
 7.0


 6o4

 6.4
 6.0***
      Smith and Loveless, S&L-6-A.
 **   275 ml. chlorine water (containing 1,957 ppm chlorine).
 ***  Adjusting for the second addition of chlorine, the following values
        are obtained:  48-F, COD = 4.56; 48-6, TOC = 6.5.
                                     105

-------
addition
               Experiment 49:  pH 6.5, 25 min. irradiation two-stage chlorine
Time
(min.)
0
0
0
0.8
2.0
4.8
9.2
9.3
9.8
10.6
11.1
13.2
15.6
15.8
16.2
18.2
20.4
20.7
21.1
23.3
23.9
25.3
27.2
27.7
28.2
36.8
36.8

Sample
49A*
49-1
C12 added**
—
—
—
—
49-2
49B
Lamp inserted
—
—
—
49-3
49C
—
—
49-4
49D
C12 added**
—
—
49-5
49E
—
49F
49-6

m
7.6
—
—
6.9
—
--
—
—
—
—
6.5
5.9
—
—
—
5.2
—
—
—
—
4.35
—
—
—
—
—
6.6
                                        Chlorine       COD         TOC
                                          '(ppm)       jppm)
                                           125

                                           109.9
                                           127.6
                                           117.7
                                            40.0
                                             2.3
                                            51.9
                                            30.0
                                             4.5
                                                    27.19
                                                    24.72, 25.52
                                                    13.55, 12.44
                                                     6.40, 6.60
                                                                   8.0
                                                                   7.4
                                                                   4.6
                                                                   3.4
                                                                   2.2***
                                                     4.64, 4.75*** —
                                                        0,0
1.8***
*    Smith and Loveless, S&L-6-A.
**   300 ml. chlorine water (containing 1,790 ppm chlorine).
***  Adjusting for the dilution produced by the second addition of chlorine,
       the following values are obtained:  49E, COD =5.1; 49-5, TOO =2.4;
       49-6, TOC = 1.96.
                                   106

-------
             Experiment 50;  pH 6.5, 15 min. irradiation

                                 Chlorine        COD         TOG
                                    (ppm)         (ppm)
Time
jjnin. )
0
0
0
1.1
1.9
4.3
4.8
5.3
9.3
10.4
10.5
11.0
14.0
16.1
16.3
17.0
19.4
20.9
22.1
22.2
25.7
26.2
26.2

Sample
50 A*
50-1
C12 added**
—
—
—
—
—
—
50-2
SOB
Lamp inserted
--
50-3
50C
—
—
—
50-4
SOD
—
50E
50-5

PJ
—
7.5
--
4.8
--
4.8
5.1
7.8
6.7
—
—
6.4
--
--
--
—
4.0
5.9
5.9
—
—
—

                                                 29.75
                                                              12
                                     168

                                     157.5

                                     162.0

                                     161.4
                                                              10
                                             24.58, 26.71

                                     75,9
                                                              5.4
                                              6.44, 6.00
                                     13.6

                                       2.1
                                                               3.4
                                              3.08,  2.92
                                       0.5
                                               2.92
                                                               3.2
    Laboratory-produced effluent, MRI-428.
**  505 ml. chlorine water (containing 1,493 ppm chlorine).


               Experiments 52-54 - Three experiments were designed to
investigate the rate and extent of UV-catalyzed chlorine oxidation at PH 3,
T>H 5 and PH 10.  The effluent  (MRI 512) used in these experiments contamed
33.8 mg/liter  COD,  13.2 mg/liter TOG,  2.5 ing/liter of ammonia nitrogen
and 4.0 mg/liter nitrate nitrogen  (average values).  In each experiment,
the effluent was treated with  chlorine water to provide an imtnal chlo-
rine concentration of  about  200 ppm.   This concentration represents a
33# excess over the theoretical amount of chlorine required to oxidize
all of the organic material  to C02 and H20.
                                   107

-------
          The experiments were performed at room temperature and were
identical, except that each was performed at a different pH (pH 3, pH 5
and pH 10) .  The experimental results are shown in Figures 12-14 (pp. 38-40).
The COD and TOC data are presented graphically in Figures 15-16 (p.  41).

          Experiment 77, the effect of nitrate concentration - In Experi-
ment 77, 20 ppm of nitrate nitrogen (as potassium nitrate) was added to an
effluent prior to treatment with chlorine.  The effluent (S&L 624A)  was
the same as the one used in Experiment 75 (Figure 22).  The results  of the
experiment (Experiment 77) with the nitrate-containing effluent are  shown
in Figure 21  (p. 45).

          Experiment 78, the effect of chlorine concentration; Effluent
S&L 624A, pH  5, continuous addition of chlorine - In this experiment, the
chlorine water was not added all at once, but was added gradually during
the irradiation period.  The results are shown in Figure 19 (p.  43).

          The effect of temperature on the UV-catalyzed chlorine oxidation
of effluents  - Two effluent oxidation experiments (Experiments 58 and 59)
were performed in exactly the same manner; except that, in one, the tempera-
ture was held near 5ฐC (41ฐF) and, in theother, the temperature was held
near 25ฐC  (77ฐp).  The results are shown in Figures 23 and 24 (pp. 47-48).
Extent  of Organic  Oxidation Produced by Chlorine in the Dark

           A  summary of the extent of COD and TOC decreases which occurred
during  a  10-min. period of chlorination in the dark is presented in
Table XXVIII.  In  each of these experiments, the TOC sample was not sub-
mitted  to the nitrogen purge; instead, it was dechlorinated by acidifica-
tion to pH 1 with  sulfuric acid, followed by treatment with excess sodium
bisulfite.
                                     108

-------
                               TABLE XXVIII
              EXTENT OF COD AND TOG ELIMINATION PRODUCED BY A
               10-MIW. PERIOD OF CHLORINATION IN THE DARK
Experiment
    No.

   48
   49
   50
   52
   53
   54
   55
   56
   57
   58
   59
   75
   77
 Average
                            COD Elimination   TOG Elimination
Effluent

 S&L-6
 S&L-6
 MRI-428
 MRI-512
 MRI-512
 MRI-512
 MRI-516
 MRI-516
 MRI-516
 MRI-525
 MRI-525
 S&L-624
 S&L-624
        a/
 pH

 3.0
 6.5
 6.5
 3.0
10
 5
 5
 5
10
 5
 5
 5
 5
16.7
 0.8
 3.3
11.8
12.1
11.3
14.7
15.4
20.0
14.4
16.4
 2.0
16.4
11.94
a/  The significance of the effluent designation is explained at the
      bottom of Table XXVII  (p.  98).
b/  These TOG results are probably in error, because the extent of the TOO
      elimination cannot be greater than the extent of COD elimination
      (These TOG results were not included in the average).
c/  In this experiment, the TOG analysis indicated an increase in TOG.
Extent of COD and TOG Elimination Produced by Irradiation at pH 5

          The following table (Table XXIX) presents a summary of the
experiments performed at pH 5 in which the COD and TOG samples were taken
separately.  The average amount of COD and TOG eliminated was calculated,
and these values are plotted vs. time in Figures 17 and 18 (p. 42).
                                  109

-------
                              TABLE  XXIX
Experiment
No.
54
56
58ฃ/
59ฃ/
75
ffjQ./
Vftฎ/
Average!/
Effluent
No.
MBI-512
MRI-516
MRI-525
MRI-525
S&L-624
S&L-624
S&L-624

Extent
5 min.
70
84
69
80
60
51
52
66.6
of COD E
(
-------
         Experiment 20:   Effluent G-2,  180 ppm chlorine,  pH 5,  15 min.
irradiation
Time
(min.) Sample pH
0 20A 7.1
0 Clp added
1.3 -- 9.2
8.5 Lamp on
11.9 — 6.4
15.3 20B
18.2
19.3 — 4.
20.3
21.3 20C 4.
* Solution was turbid.
Experiment 21:
irradiation
Time
(min . ) Sample pH
0 21A 7.05
0 C12 added —
1.3 — 10.25
10.5 Lamp on
10.8
12.0 — 9.4
13.1
15.4 21B
17 .'2
19.0 21C

Chlorine Ammonia Nitrate COD
(ppm) (ppm N) (ppm N) (ppm)
0 15.1* 0 51.6
180
116
—
105
3.5 3.6
6,0
75
2.0
7 — 4.3 3.5 28.1
Effluent G-2, 170 ppm chlorine, pH 10, 8.5 min.

Chlorine Ammonia Nitrate COD
(ppm) (ppm N) (ppm N) (ppml
0 12.7* 0 47.7
170
93
—
92
—
88
1.6 2.5
9.0
0.6 2.5 3.4 22.3
*  Solution was turbid.
                                   Ill

-------
          Experiment 25:  Effluent RC-5, 589 ppm chlorine,
15 min
Time
(min. )
0
0
2.0
6.5
10.7
14.2
15.0
15.9
18.2
28.6
30.0
dark,
Time
(min. )
0
0
1.6
4.5
9.5
13.3
15.0
16.7
18.3
21.8
27.8
31.7
. in dark^ 15 min. irradiation

Sample p_H
23A 7 .4
Cl2 added
4.8
4.7
—
23B
Lamp inserted —
__
3.9
2.4
23C
Experiment 27 :
15 min. irradiation

Sample pH
27A 7.2
Clp added
6.0
—
__ c cr
o •<_/
	
27B
Lamp inserted —
10.6*
—
—
27C
Chlorine Ammonia Nitrate COD
(ppm) (ppm W)' '(ppm N) (ppm)
0 21.4 1.65 159
389 -- — •
275
268
263
262 18.5 1.80 130
—
—
—
—
43 5.0 6.80 112
Effluent RC-3, 375 ppm chlorine, pH 5, 15 min. in
Chlorine Ammonia Nitrate COD
(ppm) (ppm N) (ppm N) ipp^)
0 20.3 2.1 156
375
—
169.5
225.6
221.3
20.8 . 1.8 134.6
— — — • —
—
53.8
11.5
9.2 3.2 7.1 123.7
*  Occasionally, an excess of sodium hydroxide was inadvertantly added.
     The pH was adjusted downward as soon as possible using concentrated
     sulfuric acid.
                                   112

-------
          Experiment  28:  Effluent RC-5,  573  ppm chlorine  (Added gradually),
 60 min.  in dark, pH maintained  above  6.5

  Tj_me                                  Chlorine        Ammonia
 (min.)         Sample         pH             (ppm)           (PPm N)

   0              28A          7.2            0               20.6
   0          Start  C12       —            373
              addition
16.8              --          6.8           49.2
26.9              —          --             75.6
37.9              --          "             60.7
45.4         Complete  C12
              addition
46.7              --          "             99-6
60.0              28B         6.4          130.5            2ป9
           Experiment 29;  Effluent RC-5, 375 ppm chlorine (Added all at once),
 60 min. in dark, pH maintained above 6.5

  Time                                       Chlorine          Ammonia
 (min.)          Sample          pH           (ppm)            (ppm N)

    0             29A           7.2            0                22.4
    0         Cl  added          —          375
  8.2             --            6.9          151.1
 12.6             —            6.9          162.6
 25.6             —            6.85         161.4
 38.0             —            6.75         155.7
 60.0             29B           6.7          140.8               6.7
                                    113

-------
          Experiment 50:  Effluent RC-5. 574 ppm chlorine (Added gradually),
60 min. in dark, 15-min. irradiation, pH 6.5
Time
(min.)
0
0

Sample
30A
Start dp

PH
7.2
—
Chlorine
(ppm)
M M
	
Ammonia
(ppm N)
22.9
—
Nitrate
(ppm N)
2.0
—
COD
(ppm)
126
--
         addition
 7.8        —       6.8
12.3        —       6.6
16.4
38.7        —       6.55
43.1  Complete  Cl2 —
         addition
58.6
60.8        30B
62.1  Lamp inserted —
77.1        —       6.9
41.2
64.1
97.3
21.8
3.3

4.2
2.6

3.1
103

 92
          Experiments 75 and 76;  The effect of adding ammonia to a highly
nitrified effluent  - The effluent used in Experiment 75 was low in ammonia
content  (1.9 ppm ammonia nitrogen).  Experiment 76 was performed using
the same effluent to which 23 ppm ammonia nitrogen (as ammonium chloride)
was added.  The  results of these experiments are shown in Figures 22 and 25
(pp. 46 and 53).

Ultraviolet-Catalyzed Chlorine Oxidation of Ammonia

          Experiments 13, 15, 17 and 26 were performed in accordance with
the general procedure, except that a solution of ammonium chloride was used
in place of an effluent.  In some cases, as indicated, the lamp was not
turned on and allowed to warm up prior to insertion into the reactor.  Except
as indicated, samples for ammonia and nitrate analyses were dechlorinated
by acidification to pH 1 with sulfuric acid, followed by nitrogen purge
until no chlorine could be detected with starch-iodide paper.
                                   114

-------
irradiation
Time
(min. )
0
0
2.7
3.7
5.3
9.8
13.8
14.8
18.3


Sample
13A
C12 added
—
Lamp on
13B
--
13C
—
13D
Experiment 15:
Chlorine
(ppm)
0.0
148.0
43.0
--
—
12.5
—
3.5
—
Ammonium chloride,
Ammonia Nitrate
(ppm W) (ppm N)
12.8
—
--
0.2 0.8
__
—
0.1 2.2
—
2.0
no chlorine, pH 5, 182 min.
irradiation

 Time
(min.)

  0
 93
182
                                               Ammonia
                                                    Nitrate
                          Sample

                           15 B
                           15 C
                           15 D
                                    12.7
                                    13.0
                                    10.8
                                 0.50

                                 0.05
          Experiment 17:   Ammonium chloride, 408 ppm chlorine, pH 5, 6 days
in dark, followed by 52 min. irradiation - This experiment was performed
in the dark using aluminum foil to cover the entire reactor.  After 6 days,
the lamp was turned on.
 Time
(min.)

  0
  0
  5.7
  8.5
 44.1
  0 (4 days
      later)
  0
  4.3
  9.6
 17.5
 20.0
 31.0
 32.0
                    Chlorine
   Sample
    17A
Cl  added
    17B
    17 C
 Lamp on
    17D
  0
408

348
293
229
213
138
 48
 32
  9.5

 115
                                                  Ammonia
                                                  (ppm N)

                                                   13.5

                                                    0.0


                                                    1.6
                                                                   Nitrate
0.02

0.22


4.0
                                                     0.0
                                                        9.0

-------
          Experiment  26:  Ammonium chloride, 504 ppm chlorine> 15 min. in
dark^ 15 din,  irradiation

 Time                                    Chlorine        Ammonia      Nitrate
                Sample        pJH          (ppm)         (ppm N)      (ppm N)

                              6.4          0              28.8           0
                                          304
                              5.6
                                          137.4
                              5.3
                                          171.8
                                          177.5
                              4.9
                                                          24.4        0.25
                                                          9.1        0.05

                              2.5
                                           36.8            4.6        6.35
                                                          4.0        6.95
    Samples  26B and 26D (150 ml.)  were acidified with concentrated sulfuric acid
       (1 ml.)  and treated with about 0.3 g. of sodium bisulfite (Reagent
       grade, Merck).  The solutions were then aerated until no odor of S02
       could be detected.  Prior to ammonia analysis, the solution was
       adjusted to pH 10 with sodium hydroxide (40$ NaOH, followed by 5$ NaOH).
**  Samples 26C and 26E (150 ml.) were acidified with concentrated sulfuric acid
       (l ml.),- and  nitrogen was bubbled through the resulting solutions until no
       trace (or only a  faint trace) of chlorine could be detected by starch-
       iodide paper.
Comparison of uy Radiation Sources

          Using the low-pressure, mercury-arc lamp, effluent oxidation experi-
ments were conducted at pH 5 and at pH 10; and the same effluent was treated
in the same manner using the high-pressure UV source.  The results of these
experiments (Experiments 55-57) are presented in Figures 27-29 (pp. 64-66).
0
0
1.5
2.3
4.3
4.8
8.6
11.7
15.0

16.9
24.2
30.0
30.0
26A
Clp added
—
—
—
—
— .
—
26B*
26C**
Lamp inserted
—
26D*
26E**
                                    116

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UV-Catalyzed Chlorine Oxidation of Pure  Compounds  (Experiments  60-65,  68-70)

          Aqueous solutions of eight pure compounds  were subjected to  condi-
tions approximating those of the effluent oxidation  experiments.

          Only the rate and extent of compound destruction were measured,
usually by TOG determinations or ultraviolet spectra analyses;  and no
attempt was made to determine the number or kind of  products formed.   In
all of these experiments, the pH was maintained near 5.0.  The  results of
these experiments are shown in.Figures 30-35 (pp.  71-76).


Investigation of the Effect of UV Eadiation, Plus Other Oxidizing Agents

          Treatment of wastewater with oxygen and UV radiation - In experi-
ment 80, pure oxygen gas was continuously bubbled through an effluent while
the reaction mixture was irradiated.  (No adjustment of pH was  made prior
to, or during, the experiment.)  In Experiment 79, nitrogen gas was bubbled
through another  sample of the  same effluent while the solution was irradi-
ated.  The results of these experiments are shown below:


          Experiment 79:  Effluent S&L-624B, nitrogen purge, no chlorine

  Time                                                              TOC
 (min.)                Sample                  pH                  (ppnQ

    0                   79A                   7.25                  12.8
    0              Lamp inserted;
                 N2 flow  started
  5.1                   79C                   7.40                  12.0
 10.0                   79D                   7.55                  11.0
 15.1                   79E                   7.70                  10.0
 20.0                   79F                  7.81
                                    117

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19.9 min.
Time
(min.)
0
0
5.1
10.1
14.9
19.9
irradiation.
Sample
80A
Lamp inserted;
02 flow started
80C
SOD
80E
80F
PH
7.32
7.50
7.60
7.75
. 7.90
TOG
(ppm)
10.2
11.0
10.0
10.0
10.2
          Treatment of wastewater with hydrogen peroxide and UV radiation -
The  same effluent used in the above series of experiments was treated in
the  dark with hydrogen peroxide in excess of the amount required to oxidize
all  of the organic material in the effluent to COg.  The reaction mixture
was  kept in the dark for 30 min. and was then irradiated for 30 min.  The
results of this experiment are shown in Figure 36  (p.  79).
Ultraviolet Absorbance of Treated and Untreated Wastewater Samples

          Ultraviolet spectra of a number of treated and untreated waste-
water samples were obtained.  A description  of the samples is presented
in Table XXX, and the absorbance values at wavelengths between 230 mj, and
340 mj, are presented in Table XXXI.

          The results of these determinations clearly show that large de-
creases in absorbance are produced by UV-catalyzed chlorine oxidation.
There are correspondingly large increases in the "Effective Depth of
Penetration" (EDp), a term which is defined on p.  85-

          The EDP is equal to the reciprocal of the absorbance; thus, an
absorbance of zero is equivalent to an EDP of infinity, an absorbance of
0.01 is equivalent to an EDP of 100 cm., and an absorbance of 1.0 indicates
an EDP of 1 cm.

          The data were obtained using a Beckman DK-2 spectrophotometer
and a cell of 1-cm. thickness.  The indicated absorbances of some of the
treated samples are very nearly zero.  Determination of more exact values
would require use of much longer cells.
                                   118

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          Note that decreases in absorbance are produced more rapidly
than decreases in COD or TOG.  For example, with effluent MRI 516, a 31.51
decrease in COD (from the pure effluent to sample 55E) wrs accompanied by
a 51$ decrease in absorbance at 260 mj,
                                TABLE XXX

        DESCRIPTION OF TREATED AND UNTREATED WASTEWATER SAMPLES
              FOB WHICH UV ABSORBANCE DATA ARE AVAILABLE
          Sample   COD    TOC     NHs  .  Nitrate
Effluent   No.*   (ppm)  (ppm)  (ppm N)  (ppm N)        Treatment

MRI 428   (50A)   29.75   12.0    2.3     15.8        None

MRI 428   (50F)    2.92    3.2     -        -         168 ppm C12, pH 6.5,
                                                        13 min. in the dark,
                                                        15 min. irrad. (Expt.
                                                        50, p. 37)

MRI 512           35.6    12.1    2.52     3.1        None

MRI 512   (54G)    0       1.6     -        -         200 ppm Cl , pH 5, 13 min.
                                                        in the dark, 28 min.
                                                        irrad. (addn'l 200  ppm
                                                        dp added after 13  min.
                                                        irrad.) (Expt. 54,  p.  40)

MRI 516           29.6    11.0    1.3     10.7        None

MRI 516   (55E)    9.3     7.0     -        -         210 ppm Clg, pH 5, 10 min.
                                                        in the dark, 30 min.
                                                        irrad. with low pressure
                                                        source (Expt. 55, p.  64)

MRI 516   (56E)    0       3.2     -        -         212 ppm C12, pH 5, 11 min.
                                                        in the dark, 12 min.
                                                        irrad. (Expt. 56, p.  65)
   The sample number is the experiment number, plus a letter designating the
     appropriate sample.  This numbering system is identical to that used
     elsewhere in the report.
                                   119

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                                                 TABLE XXXI

                      ULTRAVIOLET ABSOHEANCE OF TREATED AND UIECREAJED WASTEWATER SAMPLES


                                                  	Absorbance at  Indicated Wavelength
         Sample     Wavelength (an) - > 250    240    250    260    270    280    290    500    510    520    550    540

     MRI 428 (50A) Untreated          >1.100  0.522  0.200  0.187  0.180  0.162  0.140  0.125  0.108  0.092  0.080  0.070
        11    (SOP) Chlorinated*        0.720  0.080  0      0      0.002  0.007  0.012  0.017  0.017  0.017  0.016  0.017

o    MRI 512 Untreated                 0.600  0.510  0.245  0.232  0.218  0.190  0.160  0.153  0.115  0.100  0.090  0.075
             (54G) Chlorinated*        0.2550      0      0      0      0      0      0      0      0      0      0

     MRI 516 Untreated                 0.940  0.500  0.200  0.192  0.180  0.160  0.155  0.115  0.100  0.087  0.078  0.068
             (55E) Chlorinated*        0.760  0.240  0.140  0.095  0.075  0.070  0.072  0.070  0.064  0.055  0.047  0.040
             (56) Chlorinated*         0.580  0.060  0      0      0      0      00      0      0      0      0
   "
* Details of the chlorine treatment are presented in TABLE XXX.

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                              REFERENCES
1.  Meiners, A. F., and F. V. Morriss, "The Light-Catalyzed Oxidation of
      Starch with Aqueous Chlorine," J. Org. Chem., 29, 449 (1964).

2.  Meiners, A. F., and F. V. Morriss, "Oxidized Starch Product and Method
      of Making the Same," U. S. Patent 3,203,885 (August 31, 1965).

3.  G-rigoropoulos, S. G., and D. W. Ryckman, "The Effect of Chlorine and
      Chlorine Dioxide on Taste and Odor Causing Substances in Waters,"
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      University, St. Louis, Missouri, August 1961.

4.  Summary Report, Advanced Waste Treatment Research, AWTR-14, U.S. Dept. •
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      Pollution Control,  April 1965, p. 79.

5.  Moore, E. W., "Fundamentals of Chlorination of Sewage and Waste," Water
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6.  Young, K. W., and A. J. Allmand, "Experiments on the Photolysis of Aqueous
      Solutions of Chlorine," Can. J.  Research, 27B, 318 (1949).

 7.  Palin, A. T., "A Study  of the Chloro Derivatives of Ammonia and Related
      Compounds", Water and Water Eng., 54  (10), 151; 54 (ll), 189; 54 (12),
      248 (1950).
8.  Standard Methods-Water  and Wastewater,  12th Ed., 1965, p. 90, American
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9.  Roller,  L. R., Ultraviolet Radiation, 2nd Edition, John Wiley & Sons,
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10.  Standard Methods-Water  and Wastewater,  12th Ed., 1965, p. ,513, American
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11.   Chemical Week,  September 24,  1968, p. 23.

12.   Standard Methods-Water and Wastewater,  12th Ed.,  1965, American Public
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13.   Ludzack,  F.  J.,  "Laboratory Model Activated Sludge Unit," Journal  Water
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                                     121

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