-------
TABLE 44. STEADY-STATE TITERS OF F2 BACTERIOPHA6E CONTROLS IN FIRST
VIRUS RUN. '
Phage Titers
, pfu
Detention Time, sec
(Flow rate, I/sec)
Sample
11.4 16.8
(4.7) (3.2)
28
(1.9)
85
(0.6)
Control 2-Before UV Unit
30 sec
60 sec 2.0xl02
90 sec . -
120 sec
Geometric Mean 2.0xl02
Control 3-After UV Unit
30 sec
60 sec 2.0xl02
90 sec
120 sec
1 • ' -... •"- f
Geometric Mean 2.0x10^
Control 1-Seed Culture
Start 6.2xl06
End S.OxlO6
4.0x10'
2.4x10'
2.6x10^
1.4x10
6.0x10'
7.2x10];
9.0x10^
3
1.6x10
3
2.8x10-
2.3xl03
2.5x10-
5.8x10
3.0x10-
1.4x10-
1.4x10-
2.0x10^
2.0x10
3
210
-------
TABLE 45. TITERS OF F2 BACTERIOPHA6E EXPOSED TO ULTRAVIOLET RADIATION AT
DIFFERENT FLOW RATES IN SECOND VIRUS RUN.
Detention Time
(sec)
Flow (I/sec)
INDIGENOUS PHAGE
60 sec
120 sec
180 sec
Geometric Mean
Before UV Unit
60 sec
T.2Q sec
180 sec
Geometric Mean
After UV Unit
60 sec
120 sec
180 sec
Geometric Mean
LOG REDUCTION
Phage Titer,
pfu/ml
Detention Time, sec
(Flow rate, I/sec)
1 1 .4
(4.7)
6.2X101
3.6X101
l.SxlO1
i
3.4x10'
g.oxio2
l.OxlO3
1 . 2x1 03
l.OxlO3
6.0x10°
l.OxlO1
8.0x10®
7.8xl(#
2.13
16.8
(3.2)
4.0x10°
2.0x10°
2.0x10°
n
2.5xlOU
5.0xl02
e.oxio2
2.0xl02
3.9xl02
2.0x10°
l.QxlO1
4.2X101
1.2X101
1.52
28
(1.9)
1.2xlOV
l.OxlO1
6.0x10°
n
9.0xlOu
1.2xl03
S.OxlO2
1 . 8x1 O3
1.2xl03
4.0x10°
1,0x10°
l.SxlO1
* 3.7x10°
2.51
85
(0.6)
8.0x10°, ;
l.OxlO1
l.OxlO1
n
9.3xlOu
1.2xl03
9.8xl02
3.2xl02
7.2xl02
8.0x10°
8.0x10°
l.OxlO1
8.6x10°
1.93
*Sampling Times for the 0.6 I/sec flow were 3 minutes, 4 minutes and
5 minutes.
211
-------
TABLE 46. TITERS OF POLIOVIRUS TYPE I EXPOSED TO UV RADIATION AT DIFFERENT
FLOW RATES IN SECOND VIRUS RUN.
Virus T.iters, pfu/ml
Detention Time, sec
(Flow rate, I/sec)
Sampl e
Control 2-Before UV
30 sec
60 sec
90 sec
Geometric Mean
Control 3-After UV
30 sec
60 sec
90 sec
Geometric Mean
Before UV Unit**
0 sec
60 sec
120 sec
Geometric Mean
After UV Unit**
0 sec
60 sec
120 sec
Geometric Mean
LOG REDUCTION
*The sampling times
11.4
(4.7)
5.9xl03
4.4xl()3
4.6xl03
4.9xl03
4.9xl03
5.2xl03
4.7xl03
4.9xl03
5.3xl03
S.OxlO3
4.8X103
S.OxlO3
7-OxlO1
1 .2xl02
l.SxlO2
l.OxlO2
for C-2 and C-3 were
16.8
(3.2)
6.7xl03
6-OxlO3
6.9xl03
6.5xl03
3.6xl03
6.5xl03
6.8xl03
5.4xl03
5.4xl03
4.0xl03
3.6xl03
4.3xl03
2.5X101
2.4X101
2.6X101
2.5X101
2.23
1 , 2, and 3
28
(1.9)
8.8X103
l.lxlO4
7.6xl03
8.3xl03
l.lxlO3
5.8xl03
7-lxlO3
3.6xl03
l.OxlO4
l.lxlO4
6.5xl03
9.0xl03
1.6X101
1.2X101
1.4X101
1.4X101
2.81
minutes for
85
(0.6*)
2.6xl04
2.3xl04
2-OxlO4
2.3xl04
l.SxlO4
1.9xl04
1.7xl04
1.6xl04
l.SxiO4
1.4X104
l.SxlO4
1.4xl04
S.OxlO1
1.7X101
7.0x10°
l.SxlO1
2.97
this flow
rate.
** U.V. lights had been on for two minutes.
Other results:
All samples from the C12 contact basin were 0.
All samples for indigenous virus were 0.
Control 1 (virus feed): start = 4.0 x 107 PFU/ml
end = 2.95, x 107 PFU/ml
212
-------
may have been slightly less responsive to UV than total and fecal coliforms
during this run. A complete summary of the second virus run is given in
Table 47.
A summary of the dose-related data is given in Table 48. Due to the
much lower intensity readings, much lower indicated doses, Dj, were observed,
Contrary to the first virus run the theoretical dosages were a good approx-
imation of the indicated dosages.
THIRD UV VIRUS RUN
The third programmed UV virus run with the UPS Ultraviolet Disinfection
Unit was performed on the morning of 26 June 1975. Preparations for the
run began on 24 June when the unit was taken out of service and cleaned with
UPS cleaning solution. After draining the unit, fresh cleaning solution was
added and allowed to recirculate through the contactor all night by means of
a small externally-mounted booster pump. Early on the morning of 25 June,
the cleaning solution was flushed with tap water, and the radiometer read-
ing was 760 ywatt/cm2. However, the reading fell to 20 ywatts/cm2 follow-
ing introduction of activated sludge effluent to the unit.
It was originally planned to conduct the virus run on the 25th;
however, in view of the UV intensity on that morning it was decided to
postpone the run until the next day, and the cleaning sequence was re-
peated. Although the poliovirus stock culture had been thawed by the time
this decision was made, the F2 phage had not been added. The virus solu-
tion was,stored overnight at 5°C, and F2 phage were added to it on the
morning of 26 June.
Performance of the demonstration plant was monitored very closely prior
to the run. Grab samples of activated sludge effluent were taken at 11 AM,
1:30 PM, and 3:35 PM on 25 June for COD analyses. The results were: 122,
124, and 129 mg/1 COD, respectively. Average DO in the aeration basin was •
1.2 mg/1 in spite of efforts to increase it. On 26 June, the day of the
run, the same average DO was measured. MLVSS was 2170 mg/1. SVI was 306 ..
mg/1. The F/M ratio was 0.34 kg COD/day-kg MLSS. The aeration rate was
0.48 m3/m3. — more than adequate for the high rate operating mode with good
oxygen transfer equipment.
On the morning of 26 June the virus run commenced, in spite of the fact
that the initial radiometer reading on activated sludge effluent was only
30 ywatt/cm2. The process configuration and operating protocol were identi-
cal to the second virus run. Start-finish meter readings at each of the
four flow rates are listed on Table 49. The lowest UV intensity measured
by the IL 500 radiometer was 26 ywatt/cm2. The highest was 29 ywatt/cm2.
Analytical results of the chemical analyses are presented in Table 50.
It is clear that the influent wastewater quality for the third virus run had
substantially deteriorated. Although the level of TSS was similar to the
first two^virus runs, organic matter in the form of COD, TOC, and BOD was
213
-------
TABLE 47. SUMMARY OF RESULTS FROM SECOND VIRUS RUN
MEAN LOG REDUCTIONS
Organism
Total Coli forms
Fecal Coli forms
F2 Bacteriophage
Poliovirus Type 1
Detention Time, sec
(Flow rate, I/sec)
11.4
, (4.7)
2.19
2.33
2.13
1.69
16.8
(3.2)
3.85
3.06
1.52
2.23
28
(1.9)
3.54
3.46 '
2.51
2.81
85
(0.6)
4.26
3.67
1.93
2.97
214
-------
TABLE 48. SUMMARY OF DOSE RELATED DATA FOR THE SECOND VIRUS RUN
Flow rate, I/sec
Theoretical Detention
Time, sec
Actual Detention
Time, sec
Transmittance @
254 nm, percent
Extinction Coefficient,
cnr'
2
UV Intensity ,,uwatt/cm
Calculated Dose, DT,
ywatt-sec/cnr
Indicated Dose, Dj,
viwatt-sec/cm2
4.7 '.
11.4
10
62.5
0.48
100
8,500
8,900
3.2
16.8
15.5
62.5
0.48
97
12,500
13,400
1.9
28.2
25
62.5
0.48
95
20,900
21,100
0.6
85.1
75
62.5
0.48
97
63,100
64,700
215
-------
TABLE 49. SUMMARY OF OPERATIONS OF VIRUS RUN NO. 3
Flow (I/sec) 4.7
WQ Meter (start) 0
WQ Meter (finish)
Radiometer (start),
yw/cm2 26
Radiometer (finish),
uw/cnr
3.2 1.9
0 0
0 0
29 29
28.5 27
0.6
0
0
29
26.5
216
-------
TABLE 50. RESULTS OF CHEMICAL ANALYSES OF GRAB SAMPLES AVERAGED OVER
ALL FOUR FLOW RATES IN THE THIRD VIRUS RUN.
Parameter Influent to UV
COD, mg/1
TOC, mg/1
SOC, mg/1
BOD, mg/1
TSS, mg/1
Turbidity, NTU
Color,Pt-Co Units (filtered)
NH3-N, mg/1
Org.-N, mg/1
N02-N + N03-N, mg/1
N02-N, mg/1
PH
Sp. Cond.
Total Alk. , mg/1
TDS, mg/1
Cl~, mg/1
%Transmittance at 254 nm
75.2
28
11
22
22
11
30
10.3
6.2
0.3
0.05
.7.6
900
182
436
70
51.6
Effluent from UV
77.0
30
12
15
23
11
30..
-
-
"
.
7.5
. 900
184
- - • - • •
'
51.6
217
-------
almost double previous levels. NHs-N and organic-N were markedly higher,
and UV transmittance was significantly lower. Turbidity was three times
higher than previous runs.
Results of the microbiological samples are given in Table 51. . Influent
MPN's were 1 to 2 logs higher than other virus runs, again reflecting the
generally deteriorated wastewater quality conditions. Log coliform reduc-
tion were substantially lower and more erratic.
Results of the control sampling for F2 phage are shown in Table 52.
The influent controls in the 4.7, 1.9, and 0.6 I/sec, runs were close to the
expected values.
The respective effluent controls, however, were significantly lower.
The only explanation which can be offered is the generally poorer wastewater
quality, which may have adversely affected phage survival and recovery.
Results from exposing the seeded phage to ultraviolet disinfection are given
in Table 53. It is evident that the titers of indigenous phage were not
insignificant relative to the seeded numbers. Thus when evaluating the log
reduction values, it is difficult to ascertain which phage population con-
tributed more to the effect. In general, the log reductions were lower and
more erratic than in previous runs.
Table 54 presents the results of the poliovirus analyses of the third
virus run. As can be seen the effluent counts were higher than the previous
two runs. This was clearly due to the substantially reduced UV dosage as
a result of the marked attenuation of the UV energy by the poorer quality
wastewater. Examination of the results of the control samples before and
after the UV unit indicates that steady-state conditions were readily
achieved. A complete summary of the third virus run is given in Table 55.
Table 56 summarizes the dose-related data for the third virus run.
The dosages obtained in this run were much lower than the other two runs.
This is also evident in the disinfection data, since the worst disinfection
occurred during the third virus run.
Figures 115-118 summarize the microorganism reduction data from the
three virus runs. The runs were made during a period of equipment diffi-
culties when effluent COD values ranged from 37 to 75 mg/1. The highest
COD waters gave the poorest microbiological results, but little difference
was observed between phages and poliovirus. The phages were possibly a
little more resistant than the poliovirus, and the fecal coliforms were a
little more resistant than both the viruses, but the equations are really
not that different particularly in view of the low correlation coefficients
(0.70-0.72). Figures 116 and 117 show the individual data points and
resultant curve for fecal coliforms and coliphages, respectively, and
Figure 118 compares the curves for both these organisms with that of polio.
The no-effect dose (determined by settling y = o and solving for x) ranges
from 148 u watt-sec/cm2 for fecal coliforms to 871 y watt-sec/cm2 for
coliphages.
218
-------
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-------
TABLE 52 . STEADY-STATE TITERS OF F, BACTERIOPHAGE CONTROLS IN THIRD
VIRUS RUN.
Phage Titers
,, pfu/ml
Detention Time, sec
(Flow rate, I/sec)
Sample
Control 2-Before
30 sec
60 sec
90 sec
Geometric Mean
Control 3-After
30 sec
~-*fc
60 sec
90 sec
11.2
(4.7)
UV Un.it
l.SxlO3
l.OxlO3
l.OxlO3
1.2xl03
UV Unit
1.6xl02
2.2xl02
2.2xl02
16.8
(3.4)
6.5xl02
6.5xl02
3.7xl02
5.4xl02
3.2xl02
1.6xl02
l.SxlO2
28
(1.9)
3.3xl03
4.6xl03
4.1xl03
4.0xT03
,6.0xl02
**
4.0xl02
84
(0.6*)
8.3xl04
8.5xl04
l.OxlO4
4.1xl04
2,2xl03
2.8xl03
l.SxlO3
Geometric Mean
2.0x10"
2.1x10
2
4.9x10
2
2.2x10^
Control 1-SEED CULTURE
Start 4.6xl06
End
2.6xlOl
*Sampling on the 0.6 I/sec flow was performed at 1 minute, 2 minutes, and
3 minutes. ,
** Data not available.
220
-------
TABLE 53. TITERS OF F? BACTERIOPHAGE EXPOSED TO ULTRAVIOLET RADIATION
AT DIFFERENT FLOW RATES IN THIRD VIRUS RUN.
Phage Titers, pfu/ml
Detention Time, sec
(Flow Rates, I/sec)
Samp! e
INDIGENOUS PHAGE
60 sec
120 sec
180 sec
Geometric Mean
Before UV Unit
60 sec
120 sec
180 sec
Geometric Mean
After UV Unit
60 sec
120 sec
180 sec
Geometric Mean
LOG REDUCTION
11.2
(4.7)
4.4xl02
3,.9xl02
2.1xl02
3.3xl02
1.4xl03
1.5xl03
4.6xl02
9.9xl02
7.4X101
T.2xl02
8.7X101
9.2X101
1.04
16.8
(3.2)
3.6xl02
1.4xl02
2.0xl02
2.2xl02
7,lxl02
1.4xl03
l.lxlO3
l.OxlO3
^.OxlO1
6.0xlO]
2-OxlO1
<2.3xlO]
>1.64
28
0-9)
i .
1.3xl02
1.9xl02
S.OxlO1
l.lxlO2
2.0xl02
S.OxlO2
6.0xl02
3.3xl02
l.OxlO1
2.0X101
4.0x10° .
9.3x10°
1.55
84
(0.6*)
-
, 2.2xl02
2.4xl02
4.6xl02
2.9xl02
S.OxlO3
2.1xl03
2.5xl03
2.5xl03
S.OxlO1
l.SxlO1
l.SxlO1
S.OxlO1
1.92
*Sampling for the 0.6 I/sec flow was performed at 3 min. 4 m1n, and
5 min.
221
-------
TABLE 54. TITERS OF POLIOVIRUS TYPE I EXPOSED TO UV RADIATION AT
DIFFERENT FLOW RATES IN THIRD VIRUS RUN.
Virus Titers, pfu/ml
Detention Time, sec
(Flow Rate, I/sec)
Sampl e
11.2
(4.7)
16.8
. (3.2)
28
(1.9)
84
(0.6*)
Control 2-Before UV Unit
6.7X10'
8.5x10'
30 sec
60 sec
90 sec
Geometric Mean 7.2xlOv
Control 3-After UV Unit
5.2xlO
y.exio
7.9xio
6.8xlOc
1.5x10^
1.6xl04
1.6xl04
1.6xl04
5.9x10
6.2x10^
8.0x10^
6.6x10^
,4
30 sec
60 sec
90 sec
Geometric Mean
Before UV**
0 sec
60 sec
120 sec
Geometric Mean
After UV**
0 sec
60 sec
120 sec
Geometric Mean
Log Reduction
6.8x10°
7.0xl03
4.3xl03
5.9xl03
6.1xl03
7.2xl03
o
5.3x10°
6.2xl03
4.2xl02
S.lxlO2
7.5xl02
5.4xl02
1.06
7.3x10°
Q.lxlO3
7.2xl03
7.8xl03
9.6xl03
6.9xl03
o
7.5x10°
7.9xl03
l.SxlO2
l.SxlO2
2.2xl02
1.5xl02
1.72
1.6x10^
1.4xl04
1.7xl04
1.5xl04
1.5xl04
1.9xl04
n
1.5x10*
. 1.6xl04
1.5xl02
1.4xl02
1.7xl02
1.5xl02
2.02
2.5x10^
3.6xl04
5.3X104
3.6xl04
7.1xl04
4.3xl04
4
6.1x10*
5.7xl04
S.SxlO2
l.SxlO2
l.SxlO2
l.SxlO2
2.50
"*The sampling Time for 0.6 I/sec flow was 1
**The UV lights had been on for 2 minutes.
Other Results:
All samples from the C12 contact basin were
All samples for indigenous virus were <1. 7
Control 1 (virus feed); Start 7.55 x 107
8.45 x 10X
min, 2 min, and 3 min.
PFU/ml
PFU/ml
222
-------
TABLE 55. SUMMARY OF RESULTS FROM THIRD VIRUS RUN.
MEAN LOG REDUCTIONS
Detention Time, sec.
(Flow Rate, I/sec.)
Organism
Total Col i forms
Fecal Col i forms
F2 Bacteriophage
Poliovirus Type 1
11.4
(4.7)
<2.35
2.88
1.04
1.06
16.8
(3.2)
<1.16
1.27
Si. 64
1.72
28
(1.9)
3.42
3.19
1.55
2.02
85
(1.9)
<3.00
2.65
1.92
2.50
223
-------
TABLE 56. SUMMARY OF DOSE-RELATED DATA FOR THE THIRD VIRUS RUN
Flow Rate, I/sec
Theoretical Detention
Time, sec
Actual Detention
Time, sec
Transmittance @
254 nm, percent
4.7
11.4
10
51.6
Extinction Coefficient,
cm-1 0.65
UV Intensity,
ywatt/cm
Calculated Dose, DT
pwatt-sec/cnr '
Indicated Dose, Dj
vwatt-sec/cmz
26
4,300
2,300
3.2
16.8
15.5
51.6
0.65
29
6,300
4,000
1.9
28.2
25
51.6
0.65
28
10,600
6,200
0.6
85.1
75
51.6
0.65
28
32,000
18,700
224
-------
to
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LO
X
to °
•*"; u
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ro
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co
DOT wyojuoo ivioi
225
-------
o
UJ
or
CD
O
O
O
•a:
O
Figure 116.
LOG UV DOSE
Fecal coliform reduction vs. UV dose
226
-------
5
O
I—1
h-
O
LU
CC
CJ3
O
LU
C_J
=3;
CQ
LOG UV DOSE
Figure 117. Coliphage reduction vs. UV dose
227
-------
4 ••
O
l-H
O
LU
CO
O
3 •-
2 ..
LOG UV DOSE
Figure 118. Comparison ,of dose-response for three organisms
228
-------
10
lo3
t-
Q_
co
LU
co
'UJ
CO
10'
\
RUN No. 1 22 April 1975
RUN No. 2 13 May 1975
RUN No. 3 26 June 19775
AVERAGE PERCENT TRANSMITTANCE =51.6
AVERAGE PERCENT TRANSMITTANCE =62.5
AVERAGE PERCENT TRANSMITTANCE = 66.9
10 20 30 40 50 60 70 - 80
DETENTION TIME IN UPS UNIT, sec
Figure 119. Virus reduction versus detention time.
229
-------
SECTION 9
SUMMARY OF OPERATING EXPERIENCE
During the sixteen months in which the ultraviolet disinfection project
was conducted an extensive amount of data was collected. It would be quite
impossible to present the,results of every analytical test performed during
the project in this report. In this section the authors would like to
summarize and review some of the more significant observations made during
this research effort.
Previous data have shown that UV dose is the controlling factor in
microorganism kill, and that the percent transmittance at 254 nm is very
important to the actual dose received by the microorganisms in the exposure
chamber (13, 14). At the start of this project, we expected UV transmission
to be dependent on the turbidity of the water. The data presented in Figure
120, which is a plot of turbidity versus percent transmittance, indicate
lack of correlation.
There would similarly seem to be a potential relationship between
suspended solids and transmittance at 254 nm. Figure 121 presents these
data (averages for each of the UPS runs), and correlation is clearly lacking,
since a correlation coefficient of only 0.16 resulted. Additional efforts
to improve on these data by plotting daily values, instead of run averages,
proved fruitless. There does not appear to be any correlation between TSS
and transmittance at 254 nm, at least within the ranges observed on the
project.
Attempts were made to correlate the observed transmittance values,
which were available only after the start of the UPS unit, and several
additional water quality parameters. There is no correlation evident
between either total phosphorus or combined nitrite-nitrate nitrogen and
transmittance.
Figure 122 is a plot of percent transmittance versus the COD of the
water being processed by the UPS disinfection unit. The correlation
coefficient obtained was - 0.76, which is good for an experiment of this
type. Transmittance is plotted as a function of total organic carbon in
Figure 123. The correlation coefficient is - 0.95, which indicates very
good correlation. The fact that COD and TOC correlate well with the observ-
ed transmissibility at 254 nm indicates that the amount of soluble organic
material present in a wastewater will affect the efficiency of an ultraviolet
light disinfection process used to treat that wastewater.
230
-------
10
CQ
Cf.
25 50
TRANSMITTANCE, percent
75
90
Figure 120. The effect of turbidity on percent transmittance.
231
-------
0)
o
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n.
LU
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CO
z
«=C
72
70
68
66
62
60
58
56
54
52
50
0
Y = 0.07 X+ 64.64
r = 0.16
10
Figure 121.
20 30 40 50
TOTAL SUSPENDED SOLIDS, mg/1
Correlation between percent Transmittance and
Total Suspended Solids.
232
-------
-p
CD
O
OJ
Q.
CVJ
•a:
UJ
s:
oo
100
90
80
70
60
50
40
30
10
T = -0.31 COD + 75
r = 0.76
20 30
COD, mg/1,
40
50
Figure 122. Correlation between transmittance at 254 nm and COD.
233
-------
o
o
s_
O)
Q.
CM
UJ
o
100
90
80
70
60
50
40
30
i I
T = - 1.50 TOC + 81
r = 0.95
I I 1 I I
0 2 4 6 8 10 12 14 16 18
TOC, mg/1
Figure 123. Correlation between transmittance at 254 nm and TOC.
234
-------
The amount of organic material present in the effluent of a biological
treatment process is related to the degree of nitrification occurring;
therefore, a well-nitrified effluent should be more amenable to disinfection
with ultraviolet light than a non-nitrified effluent. In Figure 124 ammonia-
nitrogen concentrations are plotted as a function of both COD and TOC. The
correlation coefficient for the NH3-N versus TOC plot is 0.88, while the
NH3-N versus COD graph yields a correlation coefficient of 0.97. Both
correlations are excellent, and indicate that reduced concentrations of
organic compounds can be achieved by utilizing a nitrifying activated sludge
system.
Since both COD and TOC correlated well with transmittance, a correlation
between transmittance and the concentration of unoxidized nitrogen compounds
was anticipated. Figure 125 is a plot of transmittance as a function of
ammonia-N concentration. The correlation is quite good (r = -0.81), as is
the correlation between organic nitrogen and transmittance ( r = -0.77) shown
in Figure 126.
The quartz sleeves housing the UV lamps in the UPS unit were subject to
a certain amount of slime build-up since they were continuously submerged in
a secondary effluent. Slime accumulation will decrease the amount of UV
energy radiated to the surrounding water resulting in a decrease in the
unit's disinfection efficiency. Figure 127 is a time series plot of the UV
dose calculated from intensity readings. There is clearly a decrease in the
UV dose, but the initial rate of decrease observed in early October is quite
gradual. The rate of decrease observed in early November was considerably
greater than the October rate. These data indicate that the sleeves remained
clean for several weeks before significant slime development occurs but that
the slime will accumulate rapidly once started.
The UPS unit was cleaned with a proprietary compound provided by
Ultraviolet Purification Systems, Inc. in mid-November, and the UV dose
increased to the early October values. The cleaning frequency required to
keep the system operating at peak efficiency can be expected to vary with the
quality of the effluent, but intervals of about two weeks seem reasonably
consistent with these data and temperatures.
At the start of this project the factors expected to be responsible
for the number of organisms found in the effluent from a UV disinfection
system were total suspended solids, turbidity, transmissability at 254 nm,
and UV dose, among others. Figure 128 is a graph of effluent total suspended
solids versus effluent fecal coliforms. No readily apparent correlation
exists between these two data sets, or the correspondence is only poorly
defined. Attempts to quantify the suspected correlation between TSS and
coliform densities were unsuccessful. Plots using data at a constant dose
for any given run exhibited considerable scatter.
Figure 129 is a graph of effluent fecal coliforms versus turbidity, and
no significant interdependence is evident. The fact that neither turbidity
nor suspended solids have any demonstrated significant impact on the
observed effluent fecal coliform counts is a significant finding, expecially
235
-------
18
16
14
12
10
8
6
4
2
NH3-N = 0.27 COD - 3.8
r = 0.97
0 10
20
18
16
14
,_ 12
I* 10
T 8
oo
i 6
4
2
20
30 40
COD, mg/1
50
60
j-N = 0.96 TOC - 5.3
r = 0.88
T t . . . .
Figure 124.
.4 8 12 16 20
TOC, mg/1
Correlations between ammonia-N and COD and TOC.
236
-------
o
O)
Q.
LU
O
%T = (1.18)(NH0-N) + 70.83
Figure 125.
6 8 10
NH3-N, mg/1
Correlation,between NhL-N and percent
transmittance at 254 nm.
237
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10'
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20
120
40 60 80 100
TOTAL SUSPENDED SOLIDS
Figure 128. Effluent suspended solids versus effluent fecal coliforms.
140
240
-------
10C
10'
810
a;.
a.
o
0
2468
TURBIDITY
Figure 129. Turbidity versus fecal coliforms.
10
12
14
241
-------
since the result is contrary to what one intuitively would expect. One must
note that the range of turbidity arid suspended solids values observed
during this project was not great; therefore, this finding cannot be extra-
polated to very turbid water, or waters with high suspended sblids concen-
trations with any degree of confidence. However, the range of TSS concentra-
tions and turbidity values encountered during the project are likely to be
typical of municipal secondary treatment plants. And over this range,
turbidity and TSS are not particularly important water quality parameters
with respect to UV disinfection.
The only practical method that can be used at this time to routinely
monitor UV dose is the direct measurement of UV intensity at some point on
the wall of the exposure chamber. Two factors should be primarily respon-
sible for changes observed in the measured UV intensity - the light trans-
missability of the water and slime accumulation on the quartz sleeves.
Figure 130 is a plot of measured UV intensity versus percent transmittance.
There is no apparent correlation. The graph includes data for ten months,
and better results were expected. At this time no reason for the lack of
correlation can be offered except for slime growth on the quartz sleeves.
The routine measurement of UV intensity does constitute an excellent
process control procedure. Measured UV intensities and observed log reduc-
tions in fecal and total coliforms are shown in Figure 131 and 132, respec-
tively. The data plotted are from the ten month period starting on February
1, 1975 and ending November 30, 1975. Visual inspection indicates good
correlation.
The number of organisms present in an effluent disinfected with UV light
is a function of not only the applied UV dose, but also the number of
organisms present in the influent. Data"plotted for the individual runs
illustrate this point clearly. In particular Figures 99 and 100 show the
change in coliform densities in the influent and effluent observed during
Run U7.
The singularly most important factor in determining the number of
coliform organisms to be found in a UV disinfected effluent is the UV dose.
Figure 133 presents a plot of effluent fecal coliforms per 100 ml versus
UV dose, and the correlation is good (r = -0.61). These data are from Run
No. U8, and indicate that if an effluent fecal coliform count of 200 per
100 ml is desired a UV dose of at least 15,500 uwatt - sec per sq. cm. is
required.
During the discussion of individual UPS runs two dose values have been
reported, the calculated dose, Dy, and the indicated dose, Dj. A least-
squares curve fit of the average dose values for each run resulted in the
following estimating equation,
Dj = 1.27XDT - 5670
and the resulting correlation coefficient was 0.83.
242
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10
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20 30 40 50 60, 70
TRANSMITTANCE, percent
Figure 130. UV intensity versus percent transmittance.
80
90
243
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10
-1,
10
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CM
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LOG REDUCTION TOTAL COLIFORMS
Figure 131. Observed UV intensities versus log reduction in total
coliforms.
244
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LOG REDUCTION FECAL COLIFORMS
Figure 132. Observed UV intensities versus log reductions in fecal coliforms,
245
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"e
° 10
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5000 1000 ' 12000 14000 16000 18000 20000
Figure 133. Effluent fecal coliforms as a function of (N dose.
246
-------
Figure 134 presents two graphs, one of the calculated dose, DT, versus
log reductions in fecal coliforms, the other of indicated dose, Dj, versus
log reduction in fecal coliforms. The values plotted are means for each
of the UPS runs, and the estimating equations and correlation coefficients
are shown with the appropriate graph., Very good correlation was observed
(r = 0.83 for DT and 0.86 for DT) between dose and observed log reduction
value.
The same data analyses are presented for the total coliform and dose
data in Figure 135. Estimating equations and correlation coefficients
are included on the figure. Excellent correlation was observed, especially
between the indicated dose, Dj, and the observed log reductions in total
coliforms which had a correlation coefficient of 0.96. Both total and fecal
coliform log reductions correlated better with the indicated dose than the
calculated dose. This is to be expected since the indicated dose is a
better indicator of the amount of UV energy actually reaching the organisms.
Figure 136 is a plot of the log-jn of the indicated dose, Dj, versus the
log of the coliform density whose probability of exceedence is greater than
or equal to five percent. The fecal coliform densities were obtained from
the extreme value frequency distributions for each of the UPS runs, and the
dose values are means for each run. The correlation coefficient is -0.96,
which is excellent. The curve indicates that a fecal coliform density of
200/100 ml can be expected to be exceeded five percent of the time if the
indicated dose is 24,400 pwatt-sec/cm2.
Similar analyses with exceedence probabilities of one percent and ten
percent using a semi-log form resulted in correlation coefficients of
-0.88 and -0.90, respectively.
Table 57 and 58 summarize the data for the Kelly-Purdy unit and the
UPS unit respectively. Even a cursory scan of the log-reduction columns
will indicate that the UPS unit exhibited vastly superior performance.
This should be expected since the UPS unit is a modern design, and several
factors contributed to the Kelly-Purdy unit's inadequacy.
The major operational difficulty encountered with the old Kelly-Purdy
unit was sludge accumulation in the bottom of the exposure chamber. The
chamber functioned as a "shallow-tray" sedimentation basin, and the rate
of sludge accumulation was appreciable. As a result of the system
geometry, it was possible to take advantage of radiation from only 180
degrees of the lamps in the Kelly-Purdy unit, while emission from the full
360 degrees could be used in the UPS unit, making the UPS configuration
more effective.
247
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LOG UV DOSE, D
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Figure 136.
Fecal coliform densities with an exceedence
probability greater than or equal to 5 percent
versus indicated dose.
250
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INFECTION UNIT.
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SECTION 10
t
PHOTOREACTIVATION
In October 1974, a photoreactivation study was performed using clear
and amber glass sample bottles. The results indicated that exposure of UV
effluent samples to 30 minutes of sunlight produced a 1.1 log rise in
total coliforms, and a 0.6 log rise in fecal coliforms.
A study was conducted during August 1975 to see if similar observations
could be made on a pilot scale. The plant's two chlorine basins, into
which the UV unit normally discharged, were set up to operate in parallel. ••
A wooden frame covered with a black poly-vinyl chloride (PVC) sheet
was constructed and placed over the No, 2 chlorine basin to black out
sunlight. The No. 1 basin remained open to the atmosphere. In this manner,
UV effluent was split continuously to an open and a covered basin. No
chlorine was fed during this period. Figure 137 shows the arrangement of
the Demonstration Plant during this special 20-day study, which ran from
1 to 19 August 1975. Although this period overlapped two UV runs, the
operation of the UV exposure chamber was not altered for this study.
Table 59 outlines the major operating parameters of interest. Half the
flow from the UV contactor entered the No. 1 (open) basin, while the other
half entered the No. 2 (covered) basin. At flows of 1.5 I/sec, each basin
had a theoretical detention time of 65 minutes. Previous dye tests indicat-
ed the actual time to be very close to theoretical. It was assumed that
half of the irradiated effluent was subjected to 65 minutes of sunlight,
the other half to 65 minutes of darkness.
Samples of the effluent from each basin were collected over the 20-day
study period in coordination with the normal UV sampling program. In this
manner UV effluent samples corresponded to the influent of both basins.
All light-dark samples were collected in dark glass sample bottles. Samples
were taken only during daylight hours. It became evident after several
days that algae were present in both basins, although much more so in the
open (light) basin than in the covered one. The covered basin was not
truly dark as originally intended because a small amount of light seeped
around the edges of the cover.
A chemical and bacteriological summary of the light-dark sampling
appears on Table 60. Bacteriological data are reported as geometric means.
Substantial increases in MPN's occurred in both basins, although the basin
exposed to sunlight showed a larger increase. Total coliforms increased
0.7 log in the light basin, but only 0.3 log in the dark basin. Likewise,
252
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TABLE 59. PROCESS CONTROL AND OPERATION SUMMARY LIGHT-DARK STUDY: AUGUST
1-19, 1975
UV DISINFECTION UNIT
Flow
Theoretical detention time
Water temperature
UV intensity
Water quality
Transmittance (@2537 A°)
3.0 I/sec
18 sec.
28 degrees C
122 ywatts/cnr
Out of Service
63.3 percent
NO. 1 CHLORINE BASIN
Flow
Theoretical detention time
Conditions:
1.5 I/sec
65 minutes
Open to atmosphere
NO. 2 CHLORINE BASIN
Flow
Theoretical detention time
Condi ti ons:
1.5 I/sec
65 minutes
Surface covered
254
-------
TABLE 6Q. CHEMICAL AND BACTERIOLOGICAL SUMMARY OF THE LIGHT-DARK STUDY,
AUGUST 1-19, 1975
PARAMETER
Total MPN*
Fecal MPN*
DO, mg/1
Color
Turbidity, FTU
TSS, mg/1
VSS, mg/1
BOD,-, mg/1
COD, mg/1
TOC, mg/1
pH
*Geometric Mean
INFLUENT
(UV EFF)
(N)
4,600
(11)
370
(9)
1.1
(15)
23
(15)
1.3
(12)
6
(14)
4
(13)
2.3
(12)
28.8
(14)
13
04)
7.4
(15)
LIGHT
(OPEN)
(N)
21 ,000
(13)
3,800
(15)
1.9
(15)
28
(15)
1.3
(8)
17
(15)
14
(14)
5
' (12)
45.4
(15)
13
(15)
7.3
(14)
DARK
(COVERED)
(N)
9,300
(15)
2,000
(15)
1.7
(15)
27
(15)
1.1
(8)
17
(15)
16
(13)
5
(13)
42.8
(15),
14
(15)
7.3
(14)
255
-------
fecal coliforms increased by 1.0 log and 0.7 log in the light and dark
basins, respectively. The increases in D.O., VSS, and COD are indicative
of the algal masses which were present in each basin.
Figure 138 is a time-series plot of fecal coliform populations in
the: a) influent (solid line), b) open basin effluent (broken line), and
c) covered basin effluent (dotted line). In general, both basin effluents
had higher MPN's than the influent* and the coliform densities in the open
basin were consistently higher than the covered basin. (The gap from
4 August through 8 represents down-time for installation of new aeration
equipment in the No. 1 aeration basin). Figure 139 is a plot of the paired
fecal coliform populations in the open and covered basins. Clearly, the
open basin had higher population in 10 out of 14 samples.
A two-tailed t-test (15) was used to compare the log mean coliform
values between sampling points. Under the null hypothesis, H0 : y] = y2>
where y-j and y2 are tne population means being compared, the t-statistic
is calculated as follows:
t =
1
1/N-, +
1/N
, where
s
a
9 9
I + N2S2
- 2
= first sample mean with N-, data points,
s second sample mean with N2data points,
= sample standard deviation
= population standard deviation
A significance level of 0.05 was chosen to test the hypothesis. Results
are presented in Table 61. It is evident that two of the six tests failed
the null hypothesis, i.e., log influent total coliforms were significantly
different from log open basin total coliforms. All other differences
were not statistically significant. Thus, increases in total coliform
numbers likely occurred in both basins, but the increases could not be
attributed to photo reactivati on £er se. It should be emphasized, however,
that sample sizes were relatively small and that a considerably different
conclusion may have resulted if larger sample sizes had been used. Further-
more, since the covered basin was not completely opaque to visible light,
some of the increase in coliform numbers in the covered basin may still have
been due to photoreactivation.
256
-------
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INFLUENT
— LIGHT BASIN
••- DARK BASIN
10
AUGUST
15
20
Figure 138. Time-series plots of fecal coliform data for the
light dark study.
257
-------
10
10
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TABLE 61. ANALYSIS OF MEAN COLIFORM DENSITIES IN LIGHT-DARK STUDY
Log Mean Coliform Density
Parameter n influent
Total 11 2.66
Col i forms 11 2.66
Fecal 9 2.57
Col i forms 9 2.57
n Covered n Open Std. Dev.
15 3.97 1.08
13 4.31 1.18
15 3.97 13 4.31 1.09
15 3.29 1.15
15 3.58 1.25
15 3.29 15 3.58 1.22
t
3.05*
3.43*
0.91
1.48
1.92
0.66
*Significant at 95% level.
259
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REFERENCES
1. Wolf, H.W. and S.E. Esmond; Water Quality for Potable Reuse of
Wastewater. Water and Sewage Works, 121 (2): 48, 1974.
2. Wastewater Reclamation Studies in Dallas, Texas, Final Report on
Project No. 17080 EKG, Dallas Water Utilities Department and
Texas A&M Research Foundation, March 1973.
3. Research and Development Division Projects Receiving Federal
Assistance, 1969-1976, Report to the Director, Dallas Water Utilities,
1976.
4. Wolf, H.W., R.S. Safferman, A.R. Mixson, and C.E. Stringer. - Virus
Inactivation during Tertiary Treatment. Virus Survival in Water and
Wastewater Systems, J.F. Malina Jr. and B.P. Sagik, Ed. Center
for Research in Water Resources, The University of Texas at Austin
(1974).
5. Petrasek, A.C., Jr. Wastewater Characterization and Process
Reliability for Potable Wastewater Reclamation. EPA-600/2-77-210,
U.S. Environmental Protection Agency, Cincinnati, Ohio, 1977, 114pp. ,
6. Standard Methods for the Examination of Water and Wastewater, 13th ed.,
American Public Health Assoc., Inc., Washington, D.C., 1971.
7. Morrill, A.B. Sedimentation Basin Research and Design. American
Waterworks Association Journal. 24 (9): 1442-1463, 1932.
8. Thomas, H.A., Jr. and R.S. Archibald. Longitudinal Mixing Measured
by Radioactive Tracers. Transactions of the American Society of
Civil Engineers, 117:839-855, 1952.
9. Gumbel, E.J. Statistics of Extremes. Columbia University Press,
New York, 1958.
10. Benjamin, J.R. and C.A. Cornell. Probability,Statistics, and Decision
for Civil Engineers. McGraw-Hill Book Company, New York, 1970.
11. Parker, C.A. A New Sensitive Chemical Actinometer, I. Some Trials
with Potassium Ferioxylate. Proc. of the Royal Society of London.
A220:104-116, 1953.
12. Calvert, J.G. and J.N. Pitts Jr. Photochemistry. John Wiley and Sons,
Inc., New York, 1967. pp 780-813.
260
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REFERENCES (continued)
13. Roeber, J.A. and P.M. Hoot. Ultraviolet Disinfection of Activated
Sludge Effluent Discharging to Shellfish Waters, EPA-600/2-75-060,
U.S. Environmental Protection Agency, Cincinnati, Ohio, 1975. 85 pp.
14. Witherell, I.E., R. Solomon, and K.M. Stone. A Demonstration Project
to Determine the Feasibility of Using Ozone and Ultraviolet Radiation
Disinfection for Small Community Water Systems. In: Proceedings of
AWWA Disinfection Seminar, American Water Works Association,Anaheim,
California, 1977.
15. Spiegel, Murray R. Schaum's Outline of Theory and Problem of Statis-:
tics. McGraw-Hill Book Company, New York, 1961.
261
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1, REPORT NO.
EPA-600/2-80-102
3. RECIPIENT'S ACCESSION-NO.
"'ULTRAVIOLEfDISINFECTION OF MUNICIPAL
WASTEWATER EFFLUENTS
5. REPORT DATE
August 1980 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
f. AUTHOR(S)
Albert C. Petrasek, Jr., Harold W. Wolf,
Steven E. Esmond, and D. Craig Andrews
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Dallas Water Utilities
Dallas, Texas 75201
10. PROGRAM ELEMENT NO.
35B1C, D.U. B-124, Task A/06
11. CONTRACT/GRANT NO.
Grant #R-803292
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory—Cin.,OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final, 6/74-8/76
14. SPONSORING AGENCY CODE
EPA/600/14
15. SUPPLEMENTARY NOTES
Project Officer: Albert D. Venosa (513) 684-7668
16.ABSTRACT Dur.|ng ^s project two different UV exposure and irradiation systems were
studied. The first system investigated was the Kelly-Purdy Unit, which consisted of a
shallow-tray exposure chamber with 13 UV lamps mounted horizontally 10 cm above the
bottom of the chamber. This unit was operated under varying conditions of both flow
and depth and generally provided inadequate disinfection, although fecal coliform
densities were usually reduced by approximately three logs.
The second UV system used during the project was the Model EP-50 manufactured- by
Ultraviolet Purification Systems, Inc. This exposure chamber consisted of a stainless
steel pressure vessel with nine UV lamps running longitudinally through the chamber.
Each lamp was isolated from the effluent being disinfected by a quartz sleeve. The
disinfection observed on any given run was shown to be a function of the UV dose, and
greater than four log reductions in fecal coliform densities were observed at times.
During this project three special virus studies were conducted. The influent
to the EP-50 was seeded with an F2 coliphage and an attenuated Type I poliovirus.
During the three virus runs, viral and phage densities in the influent and effluent
of the UV irradiation chamber were monitored. The observed reductions in viruses were
correlated with UV doses, and the F2 co'liphage response to the UV disinfection process
was similar to the response of the Type I poliovirus.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COS AT I Field/Group
Disinfection
Ultraviolet radiation
Coliform bacteria
Wastewater, waste, treatment
Microorganism control, bactericides
Dallas, TX;
UV absorbance; Wastewatei
quality; Nitrified
effluent; Viruses;
Poliovirus; Bacteriophagfi
13B
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)'
Unclassified
21. NO. OF PAGES
282
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
262
U.S. GOVERNMENT PRINTING OFFICE: 1980--657-165/0122
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