United States
Environmental Protection
Agency
Water Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-87/006 Apr. 1987
oEPA Project Summary
Alternative Disinfectants and
Granular Activated Carbon
Effects on Trace Organic
Contaminants
Wayne E. Koffskey and Benjamin W. Lykins, Jr.
A study was conducted to evaluate
the effects of alternative disinfectants
on drinking water quality at Jefferson
Parish, Louisiana, and the ability of
granular activated carbon (GAC) to re-
move disinfection byproducts and
specific organic compounds. Bacterio-
logical information was collected on
the influent and effluent of sand and
GAC columns.
Four parallel pilot-column process
streams were dosed with a different
disinfectant (ozone, chlorine dioxide,
monochloramine, and chlorine) and
compared with a fifth pilot-column
stream that was not disinfected. After
30 minutes of disinfectant contact time,
the water in each process stream was
passed through parallel sand, GAC, and
duplicate GAC filters, each with 20 min-
utes of empty bed contact time (EBCT).
Samples collected from each process
stream were analyzed for total organic
carbon (TOC), total organic halide
(TOX), 10 volatile organics, 65 solvent-
extractable hydrocarbons, 26 chlori-
nated hydrocarbon insecticides, hetero-
trophic plate count (HPC), total
coliforms, and dissolved oxygen. To
simulate distribution conditions, ali-
quots of each column effluent were
dosed with monochloramine and free
chlorine and analyzed for TOX and 10
volatile organics after storage for
5 days at river water temperature.
The process train that yielded the
least dissolved organic contaminants
was predisinfection with ozone fol-
lowed by GAC filtration and postdisin-
fection with monochloramine.
This Project Summary was devel-
oped by EPA's Water Engineering Re-
search Laboratory, Cincinnati, OH, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
The Mississippi River along with its
tributaries drains nearly two-thirds of
the continental United States and sup-
plies a source of drinking water to many
cities located along its banks, including
Jefferson Parish. The waters of the Mis-
sissippi River and its tributaries also re-
ceive vast quantities of industrial and
municipal wastes as well as agricultural
run-off that create various levels (ng/L)
of trace organic contamination. In addi-
tion, significantly higher levels (mj/L) of
organic contamination form when chlo-
rine is used in disinfection. Therefore, a
research project, funded jointly by the
U.S. Environmental Protection Agency
(EPA) and Jefferson Parish, was ini-
tiated to determine the effect of apply-
ing various disinfectants (ozone, chlo-
rine dioxide, monochloramine, and
chlorine) to clarified and filtered water
followed by GAC adsorption.
Pilot-Column Plant
At the raw water intake of Jefferson
Parish (located on the east bank above
the mouth of the Mississippi River), raw
water is pumped to four separate treat-
ment plants. Nondisinfected clarified
water was applied to the pilot-column
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plant by the Permutit III plant (Figure 1).
Raw river water was clarified with di-
allyldimethylammonium chloride and/
or dimethylamine type cationic poly-
mers and fluoridated with fluosilicic
acid before entering the pilot-column
system. The clarified water was then fil-
tered through one of two pressure sand
filters and divided into five process
streams.
Each disinfected process stream con-
sisted of a 30-minute disinfectant con-
tact chamber followed by parallel filtra-
tion through a sand column, a GAC
column, and a duplicate GAC column.
The duplicate column was used to de-
termine variability between GAC
columns within the same process
stream. The configuration of the non-
disinfected process stream was identi-
cal to that of the disinfected process
streams except that the disinfectant
contact chamber was eliminated.
All materials used to construct the
pilot-column system (pumps, pressure
sand filters, plumbing, contact cham-
bers, and columns) were composed of
stainless steel, teflon, or glass. Plastic
flow totalizers were installed at the end
of each process stream, but all samples
were taken upstream. Each pilot column
was constructed from 6-in. ID x 10-ft
glass pipe with 150 Ib/in.2 stainless steel
flange ends and a teflon/stainless steel
screen underdrain. The pilot columns
were charged with 6.8 ft of either sand
or GAC media to obtain a 20-minute
EBCT with a flow of 0.5 gpm.
Each disinfectant contact chamber
was constructed from 12.75-in. OD
(0.18-in. wall) stainless steel pipe with
stainless steel blind flanged or capped
ends. The chlorine dioxide, monochlor-
amine, and chlorine contact chambers
were 10 ft in height in order to produce
30 minutes of disinfectant contact time
with a flow of 2 gpm. The ozone contact
chamber was 11 ft in height and de-
signed for countercurrent operation
with the water entering at the top of the
contact chamber and the ozone gas
stream entering on the bottom. The
water and ozone gas influent lines were
oriented such that the influent water
would be in contact with the ozone gas
stream for 30 minutes. Ozone gas exit-
ing the contact chamber was reduced
by passage through a heated pelletized
nickel oxide column to prevent conden-
sation.
Ozone was generated from com-
pressed dry air using an electrically
powered ozone generator with a maxi-
mum output capacity of 0.25 Ib/day.
Chlorine dioxide was generated using
two solutions, one containing sodium
chlorite and sodium hypochlorite and
the other containing sulfuric acid.
Adding a 50% excess of sulfuric acid ad-
justed the pH of the final solution to 4.
i— Cationic Polymer
Fluosilicic Acid
Mississippi River
Mile 105.4 AMP
Chloramines
Filtration
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Permutit III Turbine
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Figure 1. Pilot-column system flow schematic
2
These two solutions were pumped tc
gether and received in-line mixing in
small generating tower constructed c
teflon shavings and glass. All compc
nents that came into contact with chic
rine dioxide were made of teflon o
glass. This method generated a 96°/
yield of chlorine dioxide. Chlorine ga
was fed to both the monochloramim
and chlorine process streams usini
teflon eductors. Ammonia was added ii
the form of an ammonium hydroxidi
solution by pumping into the chlo
ramine process stream ahead of thi
chlorine eductor.
Disinfectant Effectiveness
After 30 minutes, ozone residuals av
eraged 0.5 mg/L as O3 and chlorine
dioxide 0.5 mg/L as CI02. The average
30-minute residual for chlorite was
slightly higher than that of chlorine
dioxide at 0.6 mg/L as CI02. Essentiallv
all of the chlorite resulted from the re
duction of chlorine dioxide during the
30-minute contact period. This was de-
termined by data generated from the
chlorine dioxide demand analyses per-
formed in a batch mode using deionized
carbon filtered water and nondisin-
fected pilot-column influent water. The
average concentrations of chlorine
dioxide constituents in deionized car-
bon filtered water were 1.6 mg/L CI02,
0.0 mg/L CIO2, 0.2 mg/L CI2, 0.1 mg/L
NH2CI, and 0.1 mg/L NHCI2. Those resid-
uals observed after 30 minutes of con-
tact time with the influent water of the
pilot column were 0.7 mg/L CIO2,
0.6 mg/L CIO2, 0.1 mg/L CI2, 0.2 mg/L
NH2CI, and 0.1 mg/L NHCI2. An average
chlorine dioxide demand of 0.9 mg/L as
CIO2 was seen with 0.6 mg/L or 67% re-
duced to chlorite.
Thirty-minute monochloramine resid-
ual averaged 2.1 mg/L as NH2CI or 1.4
mg/L as CI2. A dichloramine residual
was also observed averaging 0.4 mg/L
as NHCI2. The average 30-minute chlo-
rine residual for the chlorine process
stream was 1.0 mg/L as CI2 with an aver-
age monochlorine residual of 0.2 mg/L
as NH2CI and an average dichloramine
residual of 0.3 mg/L as NHCI2. The pres-
ence of 0.1 to 0.2 mg/L of naturally oc-
curring ammonia nitrogen produced
chloramines.
After 30 minutes of disinfectant con-
tact time, ozone exhibited the highest
level of disinfection followed by chlo-
rine dioxide and chlorine whereas
monochloramine was somewhat less
effective. Chlorine dioxide, chlorine,
and monochloramine became equallv
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effective after filtration through the
sand columns. As ozonated water
passed through the sand column, the
geometric mean for the HPC rose from 8
to 4594 CFU/mL, indicating a biologi-
cally activated sand column. Whereas
the geometric means for the HPC in-
creased across the sand columns for all
of the disinfected process streams, it de-
creased for the nondisinfected process
stream. Because each disinfectant be-
came ineffective in the first portion of
each GAC column, the geometric mean
of the HPC in the effluent of each disin-
fected GAC column increased to a level
similar to that observed for the nondis-
infected influent water of the pilot-
column system. Most of the colonies
picked from the heterotrophic plates
were gram positive. Of the gram nega-
tive bacteria identified, Pseudomonas,
Alcaligenes, Moraxella, and Acineto-
bacter calcoaceticas were observed
most frequently. Some positive col-
iforms were observed, especially at the
beginning of the study.
Organic Products
TOC and TOX surrogates were evalu-
ated during this study. After 30-minute
disinfection contact time, average TOC
concentrations were 3.3, 3.0, 3.3, 3.4,
and 3.3 mg/L for nondisinfected, ozone,
chlorine dioxide, monochloramine, and
chlorine, respectively. After sand filtra-
tion, the ozone stream showed a 0.5
mg/L concentration reduction. The TOC
concentrations of the other streams
were comparable to their influent val-
ues. GAC effluent concentrations at
steady state (180 days) were 2.7 mg/L
TOC for all disinfection streams exept
ozone (2.2 mg/L).
Average instantaneous TOX concen-
trations after 30-minute disinfectant
contact time were 25, 15, 85, 117, and
263 ng/L for nondisinfected, ozone,
chlorine dioxide, monochloramine, and
chlorine, respectively. TOX byproducts
were formed after disinfectant addition
except for the ozonated stream, where
an average 10 (xg/L reduction was seen.
Instantaneous TOX concentrations in
the sand column effluents were com-
parable to their respective influents.
GAC effluent instantaneous TOX con-
centrations were influenced by the
amount applied to the columns. Higher
influent produced higher effluent con-
centrations.
Flame ionization detection and elec-
tron capture chromatograms provided
an overall indication of the effect of
using various disinfectants. Compared
to nondisinfected water, chlorination
produced the most peaks followed by
chloramination, chlorine dioxide, and
ozone. (Figures 2 and 3).
For the volatile organics detected (tri-
halomethanes, 1,2-dichloroethane,
dichloromethane, trichloroethylene,
1,1,2-trichloroethane, and carbon tetra-
chloride), only the trihalomethanes
were affected by disinfection. Average
trihalomethane concentrations after 30
minutes of contact time were 1, 1, 1,4,
and 34 g/L for nondisinfected, ozone,
chlorine dioxide, monochloramine, and
chlorine, respectively. GAC removed
the trihalomethanes formed by chlori-
nation for about 60 days until break-
through and for about 80 days for those
formed by chloramination.
The nonvolatile organics identified in
the pilot system influent consisted of 28
chlorinated hydrocarbons, 16 alkylben-
zenes, 8 alkanes, 7 phthalates,
6 chlorobenzenes, 3 nitrobenzenes,
2 alkylaldehydes, tributylphosphate,
triphenylmethane, 4-nonylphenol, and
d-fenchone.
The herbicide atrazine and the insecti-
cide alachlor were present in the influ-
ent to the pilot system throughout the
study. Influent atrazine concentrations
ranged from 23 to 249 ng/L with an aver-
age of 80 ng/L. The influent atrazine
concentration was not affected by chlo-
rine dioxide, chloramine, or chlorine
disinfection. Compared with the nondis-
infected influent, however, ozonation
removed an average of 83% of the
atrazine. Alachlor levels in the nondisin-
fected influent of the pilot column
ranged from 13 to 593 ng/L with an aver-
age of 127 ng/L. Alachlor was also unaf-
fected by chlorine dioxide, chloramine,
or chlorine disinfection, but its concen-
tration was reduced an average of 84%
by ozonation.
Other chlorinated hydrocarbon insec-
ticides (CHIs) were evaluated as a total
sum of all the individual CHIs monitored
during the study except atrazine and
alachlor. The total CHI concentration in
the nondisinfected influent ranged from
18 to 88 ng/L with an annual average of
36 ng/L. The concentration of these sub-
Nondis-
infected
-JUUU-
Chlorine
Dioxide
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Chlorine
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Figure 2. Flame ionization GC profiles after idsinfeciton (runday 87).
Ozone
Chlorine
dULJL
Mono-
chloramine
Chlorine
Figure 3. Electron capture GC profiles after disinfection frunday 87).
3
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stances was unchanged after disinfec-
tion except for ozonation, which pro-
duced an average total CHI reduction of
57%.
The total alkylbenzene concentration
in the nondisinfected influent ranged
from 59 to 10,300 ng/L with an average
of 590 ng/L. Thirty minutes of disinfec-
tant contact time with chlorine dioxide,
chloramine, and free chlorine produced
an increase in the total alkylbenzene
concentration of 11%, 14%, and 100%,
respectively. Treatment with ozone,
however, reduced the total alkylben-
zene concentration by 52%. The total
alkane concentration in the nondisin-
fected influent averaged 50 ng/L with a
range of 10 to 150 ng/L. Ozonation re-
duced the concentratio'n of the total
alkanes by an average of 35%. Addition
of the other disinfectants had no effect
on the total alkane concentration.
The total phthalate concentrations in
the nondisinfected influent ranged from
70 to 470 ng/L with an average of 180
ng/L. Ozonation produced an average
total phthalate reduction of 1 1 %. No sig-
nificant changes in total phthalate levels
occurred for the other disinfectants.
Total chlorobenzene concentrations in
the nondisinfected influent ranged from
4 to 304 ng/L with an average of 100
ng/L. Nitrobenzene concentrations
ranged from a minimum of 0.1 ng/L for
2-nitrotoluene to 260 |o.g/L for 2,4-
dinitrotoluene. Ozonation produced an
average of 68% concentration reduction
for total chlorobenzene and 61% for
total nitrobenzene. Conversely, chlori-
nation resulted in a 75% increase in total
chlorobenzene and a 43% increase in
total nitrobenzene.
Two alkylaldehydes, octanal and
nonanal, were quantified. The total con-
the nondisinfected influent ranged from
below detection (<0.1 ng/L) to 37 ng/L
with an average of 14.4 ng/L. An aver-
age uniform increase in the total alkyl-
aldehyde of 144% was observed in the
ozonation system, whereas a relatively
nonuniform increase of 56% occurred
for the chlorine system relative to the
nondisinfected influent. No significant
changes in the concentration of total
chlorobenzene, total nitrobenzene, and
the alkylaldehydes were noted for the
other disinfectants.
Sand filtration had some effect on the
total alkylbenzenes, total phthalates,
total chlorobenzenes, and total alkyl-
aldehydes, with lower concentrations in
the effluent as compared to the influent.
On the average, GAC removed me cnio-
rinated hydrocarbons 90% to 97%, total
alkylbenzenes 40% to 45%, total alkanes
44% to 52%, total chlorobenzenes 93%
to 96%, and total nitrobenzenes 81% to
92% for the 1-year operational period
The removal of total phthalates by GAC
averaged 44% to 50% for about 25C
days before the ozonated stream brokt
through.
Ozone appears to be the disinfectan
of choice because lower concentration:
of organics were detected during it:
use. More research is needed, however
to understand what happens to the or
ganics after ozonation. Are these organ
ics oxidized and destroyed; are the^
converted to other organics that are
more biodegradable; are they more
water soluble and not extractable, mak
ing them difficult to detect?
The full report was submitted in par
tial fulfillment of Cooperative Agree
ment No. C8806925 by Jefferson Parish
Louisiana, Department of Public Utili
ties, under the sponsorship of U.S. Envi
ronmental Protection Agency.
Wayne E. Koffskey is with the Parish Department of Public Utilities, Jefferson.
LA 70121- the EPA author Benjamin W. Lykins. Jr., (also the EPA Project
Officer, see below) is with the Water Engineering Research Laboratory,
Cincinnati, OH 45268.
The complete report, entitled "Alternative Disinfectants and Granular Activated
Carbon Effects on Trace Organic Contaminants," (Order No, PB 87-146 700/
AS; Cost: $24.95, 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
t u iicae twu
i launmi rl.
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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