United States
                    Environmental Protection
                    Agency
 Water Engineering Research
 Laboratory
 Cincinnati OH 45268
                    Research and Development
 EPA/600/S2-87/045  Sept. 1987
&EPA          Project  Summary

                    Influence  of  Phosphate
                    Corrosion Control
                    Compounds  on  Bacterial
                    Growth
                   William D. Rosenzweig
                     The  influence of two phosphate
                    corrosion control compounds on the
                    growth and survival of coliform and
                    other heterotrophic bacteria was inves-
                    tigated.  The compounds  studied
                    included  Shan-No-Corr* (a  sodium,
                    zinc-metaphosphate) and Virchem 932
                    (a zinc-orthophosphate).
                     The investigation  was conducted in
                    three parts:

                    A.  Growth of  Citrobacter  freundii.
                        Enterobacter cloacae, and Kleb-
                        siella pneumonias was studied in
                        pure culture (laboratory) investi-
                        gations in the presence of various
                        concentrations of Shan-No-Corr
                        (0.1  to 2.0 mg/L of water, as
                        product) and in the presence of
                        Virchem 932 (0.01 to 1.0 mg/L
                        of water, as zinc). In some exper-
                        iments Fe2O3 (100 ijg/L). an iron
                        corrosion product, was also
                        added.

                    B.  Field  investigations were con-
                        ducted in three water distribution
                        systems. Two interconnected
                        systems received  Shan-'No-Gorr
                        and the third Virchem 932. Total
                        coliform, total heterotrophic bac-
                        teria, and 16 different physico-
                        chemical parameters of the water
                        were measured, twice  weekly,
                        before  and after the addition of
                        the  corrosion control com-
                        pounds. Statistical correlations
                        were sought among  observed
                        changes in bacterial counts and
                   'Mention of trade names or commercial products
                    does not constitute endorsement or recommenda-
                    tion for use
     the various  physicochemical
     water parameters.

  C.  Model system studies were con-
     ducted  by  adding coliform (C.
     freundii) and other heterotrophic
     bacteria to a model water distri-
     bution  system, establishing a
     steady-state bacterial population,
     adding the  phosphate  corrosion
     control compounds, and  then
     comparing  the growth  of the
     bacteria before the addition of the
     phosphate compounds to growth
     after the additon.

  Results presented  no evidence that
 the corrosion control  compounds stim-
 ulated coliform  growth and some
 evidence that  they might inhibit
 growth. Growth of the other heterotro-
 phic  bacteria might  be stimulated by
 the compounds, although the evidence
 is not conclusive.
  This Project Summary  was devel-
 oped by EPA's  Water Engineering
 Research Laboratory, Cincinnati,  OH,
 to announce key  findings of the
 research project  that is fully docu-
 mented in a separate report of the same
 title  (see Project Report ordering
 information at back}.

 Introduction
  One major problem facing water utility
 companies is the control of pipe corro-
 sion.  Each year, hundreds of millions of
 dollars are spent by utility companies to
 maintain and replace pipes damaged by
corrosion.
  Different treatment  methods exist to
prevent pipe corrosion  in water distribu-
tion systems. The  most common treat-

-------
ments are those that rely on the addition
of various inorganic compounds that will
form a protective film on the walls of the
pipes. Included in  this group are car-
bonates, silicates, and phosphates
  Phosphate  corrosion  inhibitors are
quite popular and  have  been used for
over 30  years.  They come  in three
principal forms  orthophosphates, bime-
tallic phosphates, and molecularly dehy-
drated polyphosphates

Objectives of the Project
  Due to a lack of  information  on the
influence of phosphate  addition (for
corrosion control) on microbial  growth
and the potential  public health  signifi-
cance, the objective of this project was
to determine the influence of phosphate
addition for  corrosion control in water
distribution systems on the survival and
growth of cohform  and other heterotro-
phic bacteria.  Correlations  between
bacterial  growth,  phosphate  addition,
and various physicochemical parameters
(i e., pH, temperature, chlorine levels) of
the water were also investigated

Materials and Methods
  The influence of phosphate  corrosion
control compounds on the growth  of
cohforms and other heterotrophic bacte-
ria  was determined by comparing bac-
terial growth  in  the presence and
absence  of the compounds  Investiga-
tions were performed on three levels:

  A  Pure culture  investigations in the
     laboratory.

  B  Field investigations in three, small,
     public groundwater distribution
     systems.
  C  Model system investigations in the
     laboratory

  This investigation utilized two  com-
mercially available phosphate corrosion
control  compounds. Shan-No-Corr,  a
sodium,  zinc-metaphosphate  manufac-
tured by the Shannon Chemical Com-
pany, Malvern,  PA,  and Virchem 932, a
zmc-orthophosphate manufactured  by
Technical Products Corporation, Ports-
mouth, VA

Pure Culture Investigations
  Experiments  were performed in the
laboratory to determine the  influence of
various concentraitons of Shan-No-Corr
and Virchem 932 on the growth of pure
cultures of C. freundii (ATCC 8090), E.
cloacae (ATCC 13047), and K. pneumo-
niae (ATCC 13883).
  Cohforms for the studies were cultured
for  24 hr in tryptic-soy broth (Difco).
Serial dilutions  of 1 mL of this culture
were done in sterile saline (0.85% w/v,
pH 7.0) to obtain a final dilution of 10~6.
A 1 -mL dose of this suspension (approx-
imately 1,000 to 6,000  cells/mL) was
then added to 99 ml of sterile, dechlo-
rinated tap water (in a  250 ml flask)
amended with  a  phosphate corrosion
control compound. The tap water was
batch dechlormated with activated car-
bon and  sterilized by membrane filtra-
tion. Shan-No-Corr concentrations  of
01,02, 0.3, 0.5, 1.0, 1.5, and 2.0 mg/L
(as  product) were tested. In the case of
Virchem 932, the concentrations tested
were 001, 0.1, 0.3, 0.5, 0.75,  and 1.0
mg/L (as zinc). In both studies, tap water
without the phosphate corrosion control
compound was used as a control. Various
chemical characteristics of each batch of
tap  water (total and free chlorine,  pH,
alkalinity,  turbidity,  sparged and non-
sparged  total  organic  carbon,  total,
f iltrable, and dissolved solids, nitrogen as
N02-N03, zinc, orthophosphate, and total
phosphate) were  determined,  prior  to
dechlormation,  according to Standard
Methods (1985) The flasks were incu-
bated at  25°C and  the coliforms were
counted after 24, 48, and 168 hr by the
spread plate procedure using one-tenth-
strength tryptone-glucose-yeast agar as
the plating medium, an incubation time
of 48 hr for C.  freundii and E. cloacae
and 168  hr for  K. pneumoniae, and  an
incubation temperature of 35°C.
  Since the phosphate corrosion control
compounds interact with iron corrosion
products, it was of  value to determine
if there  were  any  synergistic  effects
between the iron corrosion products and
the phosphate  compounds on  coliform
growth. To test  this, pure culture exper-
iments, as described above, were con-
ducted with the addition of 100 //g of iron
(as  FesOsl/L of water. An  additional
control, consisting of tap water, FeaOa,
and no phosphate compound was added.

Field Investigations
  A field  study  was  undertaken  to
deter mine the influence of Shan-No-Corr
and Virchem 932  on the growth  of
coliforms and other heterotrophic bacte-
ria  in operating  water  distribution
systems.
  Three, small, public, water distribution
systems m Chester County, PA, were
used in the field investigations:

 A.  Bradford Glen: supplies  ground-
     water chlorinated at a dose of 1.0
     mg/L.  The system  consists  of
     100%  ductile iron  pipes and
     approximately 250 services. The
     system was started in 1975 and
     portions are under construction as
     houses are being built.
 B.  Spring  Run: supplies groundwater
     chlorinated at a dose of 1.0 mg/L.
     The system consists of 30% ductile
     iron/70% asbestos/cement pipes
     and  approximately 220 services.
     The  system was  installed during
     the period 1972-1975.
 C  Federal Drive: supplies  ground-
     water chlorinated at a dose of 1.0
     mg/L.  The system  consists  of
     100% ductile iron pipes  and  67
     services. The  system was  installed
     during the period 1972-1 975.

Sampling
  The systems were sampled,  at least
twice a week, at or near the source water,
at  system  midpoint, and at  the  end.  At
each sampling site, four 900-mL serial
water samples were collected in clean,
sterile polypropylene bottles containing
0.2 mL of a 20% (w/v) sodium thiosulfate
solution added  before  autoclaving. The
sodium thiosulfate was added to neutral-
ize any residual chlorine present in the
water. All  samples were protected from
sunlight and transported with non-
contaminating artificial coolants to the
laboratory for  immediate processing. A
pre-additive, 1985  (prior to addition of
either Shan-No-Corr or Virchem 932)
sampling phase of 2 months for  Bradford
Glen and Spring Run and 3 months  for
Federal  Drive was performed to deter-
mine the background bacteriological and
chemical profile of the systems. After the
pre-additive sampling  phase, the phos-
phate corrosion control compounds were
added and sampling (1985 post-additive
phase) continued until the winter. Sam-
pling was stopped during  the winter,
although  the phosphate  compounds
were added throughout  the  winter.
Sampling  resumed the following spring
(1986 post-additive phase).

Addition of Phosphate Corrosion
Control Compounds

-------
  After the pre-additive, 1985 sampling
phase, Shan-No-Corr  was  added  to
Bradford  Glen and Spring Run (treated
as one system because of an intercon-
nect) water at a rate of 3.0 mg/L (as
product) for 4 months (for passivation)
and then  reduced to 1.0 to 1 5 mg/L (for
maintenance). Virchem  932 was added
to Federal Drive water at a rate of 1.0
mg/L (as  zinc) for 1  month  (for passi-
vation) and then reduced to 0.3 mg/L (for
maintenance). The pH of all systems was
adjusted to pH 6.5 to 7.0, according to
manufacturer recommendations,  with
commercial caustic soda (50% NaOH)

Bacteriological  Analysis
  The following  bacteriological tests
were performed on the samples'

  A.  Portions of each sample (100 mL)
     were analyzed for total cohforms by
     the  membrane filter  procedure
     (Standard Methods, 1985)  using
     mENDO LES medium  (Difco) and
     24  hr incubation at 35°C. Typical
     coliform colonies were  verified by
     growth and gas production in lauryl
     tryptose broth (Difco) and brilliant
     green bile broth (Difco). Approxi-
     mately  23%  of  verified  isolates
     were identified by the API Rapid E
     system (Analytab Products).
  B.  Heterotrophic plate counts were
     performed on 5 to 20 mL portions
     of each sample by the  membrane
     filter    procedure    (Standard
     Methods,   1985)  using   R2A
     medium and  168 hr incubation at
     28°C. After  incubation, the  colo-
     nies were counted and categorized
     by color (red, orange, yellow, and
     other). For comparative purposes,
     every fifth  sample was analyzed
     (total counts only) by  the spread
     plate    procedure    (Standard
     Methods, 1985) (1  mL  of sample,
     R2A medium, and 168  hr incuba-
     tion at 28°C) and by the standard
     pour  plate  procedure  (Standard
     Methods, 1985).

Chemical Analysis
  Various physicochemical parameters
of the water were  determined (Standard
Methods, 1985). Free and total chlorine
and temperature were measured in the
field while turbidity; pH; alkalinity; total,
filtrable, and dissolved solids;  orthophos-
phate,    total   phosphate   (acid-
hydrolyzable); non-sparged and sparged
total  organic carbon;  nitrite-nitrate
nitrogen; zinc; and calcium were mea-
sured in the laboratory.

Model System Investigations
  A model water distribution system was
constructed as the third component of
this research
  The model system was a re-circulating
system (Figure 1) and consisted of three
asbestos/cement and three ductile iron
pipe segments (4-inch diameter, 3 feet
in length). Each  pipe  segment  was
supplied with Bradford Glen well water
from  a  10-gallon  reservoir.  Polyvinyl
chloride  tubing  connected each  pipe
section to its own individual  reservoir.
For each pipe type, one segment served
as a control, one received Shan-No-Corr,
and the third received Virchem 932. The
system was inoculated with heterotro-
phic bacteria to establish a steady-state
population of approximately 104 to  10s
cells/mL. The heterotrophic population
consisted of coliform and  non-cohform
bacteria  isolated from  the distribution
systems  They were added at approxi-
mately the same  ratio (colifornrrnon-
coliform)  observed in  the  distribution
systems  The  model system was run at
25°C and  at a flow  rate  (0.3 ft/sec)
sufficient to induce turbulent flow and
insure complete mixing of the water.
  At the conclusion of the last experi-
ment, various parts of the model system
were sampled for cohforms  Areas
sampled  included the inner wall surface
of the ductile iron and asbestos-cement
pipes, reservoirs, and the  polyvinyl
chloride tubing. Sampling  was accom-
plished by swabbing each area with two
sterile cotton swabs andthen placing one
swab into a tube of lauryl tryptose broth
     (Difco) and the other into tryptic-soy broth
     (Difco). In the case of the pipes, a sterile
     stainless steel  spatula was used  to
     scrape the pipe wall  and  the collected
     material was placed into the broths. Use
     of the spatula was necessitated by the
     rough surface of the pipe  walls. Swab-
     bing  with a cotton swab  would have
     resulted in loss of the cotton from the
     swab. Tubes demonstrating growth after
     48 hr were examined for  cohforms  by
     standard procedures (Standard Methods,
     1985).
       The model system  was  generally
     sampled daily following the same pro-
     tocol used in the field investigations. The
     influence of the following physicochem-
     ical parameters on the growth of the
     bacteria were tested:
      A.  Phosphate  corrosion   control
          compounds.
      B.  As in A but with the pH increased
          from approximately 6.2 (natural pH
          of the water) to 8.5.

      C.  Phosphate corrosion control com-
          pounds along with an  assimilable
          carbon source (50 /^/g of total
          organic carbon as glucose/L  of
          water).
       Each  experiment  was  run until  a
     steady-state (or  predictable rate  of
     growth) heterotrophic population (coli-
     form and  non-coliform) was  attained.
     Prior to the beginning of each  new
     experiment, the heterotrophic population
     within  the  system  was  adjusted  (if
     necessary) to the  starting  point of 103
     to 104cells/mL.
      Reagent/Culture
      Addition
      10-gal
      Reservoir
                                    Pump, Mag Drive, Polypropylene
                                    Head and Fittings
                                   Sampling
rjaiii/jiiny

 r—  "    —|
Figure 1.   Diagram of model system.

-------
Analysis of Data
  Analyses were performed using the
BMDP Statistical Software available on
Prime  computer systems,  and no data
were treated as outliers.

Pure Culture Investigations
  The equivalence of repeated runs with
the same compound - organism set was
tested  by one-way Analysis of Variance
(ANOVA), grouped by run.  At the same
time the Levene test for equal variances
was performed The significance of
grouped  means was  tested over  the
range  of  concentrations  by multiple
linear regression, and against the control
by Student's t-test.

Field Investigations
  Field data were tested by  both para-
metric and  non-parametric  methods.
Correlations of bacteriological and phys-
icochemical  parameters over the  test
period were sought using multiple linear
regression for all systems  combined or
simple linear regression for individual
systems.  Spearman and  Kendall  rank
correlations were also performed for the
same  data sets. The  significance of
correlations was tested using,  where
appropriate, tables of critical values for
the appropriate r- or  t-transforms
  Equivalence of parameters for the pre-
additive and  post-additive  periods was
tested by a one-way  ANOVA grouped by
period and the significance of differences
further tested by a separate-variance t-
test. In addition, simple linear regres-
sions  on  the  two data sets  were also
performed  and tested by appropriate
methods. Both direct and LOdo bacterial
counts were used in  these analyses.

Results and Discussion

Pure Culture Investigations
  Growth of C.  freundii, E.  cloacae, and
K. pneumonias was  followed  in  the
presence of  various concentrations of
Shan-No-Corr and Virchem 932 in
dechlorinated, filter-sterilized tap water.
In the  presence of Shan-No-Corr there
was no significant (Student's t-test and
multiple linear regression  analysis)
pattern of growth inhibition or stimula-
tion when compared to the control after
24,48, 168 hr of incubation The addition
of 100 /ug/L  of iron (as Fe203) did not
change the results.
  In the presence of Virchem 932 growth
of E.  cloacae was not significantly
(Student's t-test)  different  from  the
control. C. freundii showed a significant
(Student's t-test) decrease  in growth
(Table 1) after 48 and  168 hr of incu-
bation in the presence of 0.3 mg/L and
above of Virchem 932. At concentrations
less  than 0.3  mg/L or after 24 hr of
incubation, there  was no  significant
difference in  growth.  K.  pneumoniae
showed a significant (Student's t-test)
decrease in  growth (Table 2)  after all
three incubation times  and generally at
Virchem 932 concentrations of 0.3 mg/
L and above. The addition of 100 //g/L
of iron to the  tap water enhanced the
inhibitory action of the Virchem 932 with
all three  coliforms significantly (Stu-
dent's t-test) inhibited.
  Chemical analysis of the  tap water
used in the pure culture  investigations
indicated that the different batches of tap
water used were uniform and did not vary
greatly in their chemical properties.
Field Investigations
  Investigations were performed in three
water distribution  systems comparing
coliform and  heterotrophic  bacterial
counts prior to the addition of phosphate
corrosion control compounds to counts
obtained after the addition of  the com-
pounds. In  Bradford  Glen (BG), Spring
Run (SR), and  Federal  Drive  (FD) the
mean total coliform counts per 100 ml_
                             sample for the period prior to the addition
                             of the corrosion control compounds (pre-
                             additive 1985) were 2.14,1 19, and 1  88,
                             respectively (Figure 2). Mean heterotro-
                             phic bacterial counts per mL were 6.43
                             for BG, 7 29 for SR,  and 5 33  for FD
                             (Figure 3) After the addition of Shan-No-
                             Corr to BG and SR and Virchem  932 to
                             FD (post-additive  1985), there was no
                             significant change (Student's  t-test) in
                             the mean total coliform counts (Figure
                             2).  However,  the mean heterotrophic
                             counts increased significantly (Student's
                             t-test)  in BG and SR (Figure 3). There was
                             no significant change in FD. The  corro-
                             sion control compounds were added over
                             the  1985-1986 winter and sampling
                             resumed in the spring of  1986  (post-
                             additive 1986)  Mean total  coliform
                             counts obtained in 1986 were signifi-
                             cantly  lovver (Student's t-test) m BG and
                             FD when compared to the  pre-additive
                             1985 counts (Figure 2). Although lower,
                             the count  in SR was not significantly
                             different from  the 1985 count.  Mean
                             heterotrophic counts  obtained in 1986
                             were  significantly (Student's  t-test)
                             increased  in all three systems  when
                             compared to the  pre-additive  1985
                             counts (Figure 3).
                               Statistical analyses revealed little
                             evidence  that the corrosion inhibitors
                             stimulate  coliform  growth in  water
Table  1.
Growth ol'Citrobacter Freundii in the Presence of Various Concentrations of Virchem
932
Time Cone
(hi {mg/L}
24 O.O
0.01
0.1
0.3
0.5
0.75
1.0
48 00
0.01
0.1
0.3
0.5
0.75
1.0
168 0.0
0.01
0.1
0.3
0.5
0.75
10
Mean Cell Count
+ SD (per ml}*
4O4O ±
180.6 +
252 7 +
28.6 ±
77±
7.3 +
4.3 +
12.3 +
31.9 ±
8.2 ±
02±
57 ±
345 ±
4.3 ±
66 +
65±
7.0 ±
39 +
1.8 +
2.9 ±
05 +
691 2O
275.38
442 10
1932
10.46
7.20
4.14
19. 38 £4
56 34 E4
14.98E4
028 E4
1003 E2
3541 E2
3.60E2
1 61 E5
1.40 E5
257E5
3 14 E5
2.61 E5
3.69 E5
054E5
Level of
Significance^

/VS
/VS
/VS
/VS
/VS
NS

/VS
/VS
<0.02
<0.05
<005
<005

NS
/VS
<002
<0001
<0001
<0001
"Mean of 4 runs. 3 plates/run
^Student's t-test; NS, not significant (p >0.05J

-------
Table 2.
Time
Growth of Klebsiella Pneumomae in the Presence of Various Concentrations of
Virchem 932
                  Cone
                 (mg/L)
                          Mean Cell Count
                           + S.D. (per ml)*
                              Level of
                            Significance^
  24
  48
       00
       0.01
       0 1
       03
       05
       075
       1 0

       00
       0.01
       0 1
       03
       05
       0.75
       1 0
 96 1 ± 71.03 E3
1055 +81 13E3
 19.4±  6.47E3
  6.0 ±  3.39 E3
  57 ±  793E3
  1 2 ±91 OOE3
  1.1 ±  036 E3

 93.8 + 20.38 E4
131 0 ±5806E4
 970 + 1728E4
 382 ±3801 E4
  6.7 +  4.72 E4
  1 9±  1 69E4
 29.2 ± 42 85 E4
                                                                     NS
                                                                   <0.01
                                                                   <0.002
                                                                   <0002
                                                                   <0.05
                                                                   <0.002
                                                                     /VS
                                                                     /VS
                                                                   <0.002
                                                                   <0.002
                                                                   <0.001
                                                                   <0.001
168






00
001
0.1
03
05
0 75
1 0
85 ± 1 06 E5
126+ 321E5
8 1 ± 1 15 E5
5.9 ± 1.96E5
6.6 ± 361 E5
54 + 344E5
55+ 277E5
--
<0005
NS
<0002
/VS
<005
<0.01
 'Mean of 3 runs, 3 plates/run
 UStudent's t-test. NS. not significant (p >0 05)



25 •


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Mean Cell ; 5 .
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iaj Pre-Corrosion
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l~l Post-Corrosion
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11986)


                      BG       SR
                             System

 Figure 2.    Mean total coliform counts
distribution  systems.  In  addition,  the
observed increase  in  heterotrophic
counts, after the addition of the inhib-
itors, could not be conclusively correlated
to the phosphate compounds   While
strong, consistent correlations do exist
between  the heterotrophic  counts  and
indicators of the presence of the mhib-
                               FD
                             itors  (e.g ,  total phosphates and  zinc),
                             they  are tempered  by other strong
                             correlations  in  uncontrolled  water
                             parameters such as nitrogen levels
                               The API Rapid E system identified 23%
                             of the isolated coliforms. C.  freundii, E.
                             cloacae, and K. pneumoniae accounted
                             for 94% of the identified isolates prior
to the addition of the phosphate corrosion
control compounds  and  81% of the
isolates after the addition.
  The spread plate procedure using R2A
medium and 28°C for 168 hr proved far
superior to  the  standard pour  plate
procedure  in  recovering heterotrophic
bacteria. Counts  were 10 to  13 times
higher with the spread plate procedure
than with the pour plate method.

Model System Investigations
  Six experiments were conducted with
the model system and consisted of the
following treatments of the water:
  A.  Passivation  dosages  of Shan-No-
     Corr and Virchem 932.
  B.  Maintenance dosages of Shan-No-
     Corr and Virchem 932.
  C.  Same as B.
  D.  Maintenance dosages of Shan-No-
     Corr and Virchem 932; pH of water
     adjusted to 8.0
  E.  Maintenance dosages of Shan-No-
     Corr and Virchem 932 plus 50 ug
     of carbon as glucose per L of water.
  F.  Same as E.

  The model system  was inoculated at
the beginning of  each experiment (if
necessary) with  non-coliform  hetero-
trophs and  C. freundii to  achieve  an
approximate total  population of 104 to
105/ml_ (C. freundii population approx-
imately 101 to 102/100 mL). All exper-
iments were  run for  2  to 5  weeks.
Experiment A, which  ran for 5 weeks,
was re-inoculated with C. freundii (to a
level of 104/100 mL) after approximately
2 weeks.
  In*  all experiments  we  were able to
establish the desired non-coliform het-
erotrophic population, however, we were
unable to establish a coliform population
that  was  detectable  by  the  standard
membrane  filtration  procedure. The
various treatments did not appear to have
any influence on the survival and growth
of  the  established  heterotrophic
population.
  Swabbing various parts of the model
system (pipes, tubing, reservoirs) isolated
bacteria. However, none of the isolated
bacteria were coliforms

Conclusions and
Recommendations

  1   There is little evidence that either
     Shan-No-Corr  or Virchem  932

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  Log Mean
  Cell Count
  per mL of
   Sample
1.8-,
1.4.
1.2-
10-
0.8-
0.6-
0.4-
0.2 •



I


vwr
\




I
—
BG SR FD
System
                                             LJ  Pre-Corrosion
                                                 Control Additive
                                                 I1985J

                                             T7\  Post-Corrosion
                                                 Control Aditive
                                                 {1985}

                                             CD  Post-Corrosion
                                                 Control Aditive
                                                 (1986)
Figure 3.    Log mean total heterotrophic plate counts
 3.
stimulate coliform growth or sur-
vival in water distribution systems.
However, the pure culture inves-
tigations suggest that coliform
growth is inhibited by Virchem 932.

While field studies with Shan-No-
Corr and Virchem 932  resulted in
increased  heterotrophic  counts,
this increase could not be conclu-
sively correlated to the presence of
the phosphate corrosion  control
compounds. Strong,  consistent
correlations do exist  but are tem-
pered by other strong correlations
in uncontrolled physicochemical
parameters such as nitrogen.
The field portion of this investiga-
tion was probably not of sufficient
duration to get a good picture of
the relationship between the phos-
phate corrosion control compounds
                                            and bacterial growth. Yearly sam-
                                            pling over  a 5-year (minimum)
                                            period would probably be  more
                                            reasonable.

                                         4.  It might be  of  value  to  analyze
                                            sampling data of water companies
                                            that add phosphate corrosion con-
                                            trol compounds to their water.
                                            Many companies have been adding
                                            these compounds for decades. A
                                            comparison of  pre-  and  post-
                                            additive data from such companies
                                            might reveal a relationshp between
                                            bacterial growth and the presence
                                            of these compounds.
  The  full report was submitted in
fulfillment of Cooperative Agreement No.
CR-811613-01-0  by  Drexel University
under  the sponsorship of the  U.S.
Environmental Protection Agency.
   William D. Rosenzweig is with Drexel University, Philadelphia, PA. 19104.
   Donald J. Reasoner is the EPA Project Officer (see below).
   The complete  report  entitled  "Influence  of Phosphate  Corrosion  Control
   Compounds on Bacterial Growth."(Order No. PB 87-198 297/AS; Cost: $13.95,
   subject to change)
   will be available only from:
          National Technical Information Service
          5285 Port Royal Road
          Springfield. VA 22161
          Telephone: 703-487-4650
   The EPA Project Officer can be contacted at:
          Water Engineering Research Laboratory
          U.S. Environmental Protection Agency
          Cincinnati, OH 45268

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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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           0000329   PS
           U  3  ENVIR  PROTECTION AGENCY
           CHICAGO

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