United States
Environmental Protection
Agency
Municipal Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-82-101 Mar. 1983
Project Summary
Performance Characteristics of
Package Water Treatment Plants
James M. Morand and Matthew J. Young
The quality of water produced by
package water treatment plants was
investigated in a study conducted on-
site at six selected facilities. These
sites are but a small sample of the more
than 500 package installations identi-
fied by manufacturers and state agen-
cies through a questionnaire. The list
by no means includes all package
plants operating in the United States.
The six selected plants were in year-
round operation, used surface water
sources, and served small populations.
The plants were monitored to assess
their performance and ability to supply
water meeting the Interim Primary
Drinking Water Regulations.
At each plant, grab samples of the
raw water, the treated water, and water
from the distribution system were col-
lected intermittently over a 2-year
period. Data on turbidity, total coli-
forms, and chlorine residuals were re-
corded on all visits. Standard plate
counts, chemicals listed in the U.S.
Environmental Protection Agency Drink-
ing Water Regulations, and trihalome-
thanes were determined intermittently.
Only one treated water sample (a
distribution sample) showed any coli-
forms. Sixty-eight percent of the stand-
ard plate counts for treated water
showed densities of 10 or fewer organ-
isms per milliliter.
Three of the plants met the 1-ntu
turbidity standard on nearly all occa-
sions, whereas the other three plants
met it on fewer than half of the sam-
pling trips. Failure of the latter plants
to perform well is attributed to the
variability and quality of their raw water
sources and/or to the lack of skilled
operators with sufficient time to de-
vote to treatment.
This Project Summary was developed
by EPA's Municipal Environmental 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 problem of providing acceptable
water supplies to the public is particularly
acute for small communities with limited
financial resources and a lack of compe-
tent treatment plant operators. Isolated
recreational areas also must provide ac-
ceptable drinking water to their visitors
and staff, often without skilled or experi-
enced water treatment personnel.
During the last 20 years, cost savings
have been achieved in such situations by
using package water treatment plants. A
package plant generally consists of pre-
fabricated and largely preassembled clari-
fication and filtration units (Figure 1).
These plants are reputed to require mini-
mal operational skill and to be a viable and
economical low-flow alternative to the
custom-built facility. Six such plants were
selected for study (Tables 1 and 2). These
plants were monitored to assess their
performance and ability to supply water
meeting the National Interim Primary
Drinking Water Regulations, particularly
the turbidity 'and microbiological require-
ments.
The design of a custom-built treatment
plant should depend on an evaluation of
the nature and quality of the particular
water to be treated. Package plants are
designed with the goal of producing a
satisfactory quality of treated water from a
range of influent waters. Flow rates for
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03=
Flocculator
Backwash
Waste Valves
Tube Settlers
V.
Filters
r-
;
! i !; 'I In i
1 I 'Ml l'| i
J ii u {-~trrrdi I
{TVMfjj ft '
i i ! i!::ji
NI i i, n 'i
o-oti — r~ tra-a
1
1
Hj
1 — W
r
P
L_
i X
-i ~-^--
1 — "J^-—
\
Effluent and
Backwash Valves
fi
1 — I]L
Figure 1. Neptune Microfloc AQ-40 Water Treatment Plant (200 gpm capacity).
plants on the market range from 10 to
2100 gpm.
The financial and personnel limitations
faced by small communities and recrea-
tional areas can be alleviated by prefab-
ricated plants of this type. The question of
the adequacy of treatment provided by
these plants as they are managed and
operated by small communities and recre-
ational areas is not answered by data
available in the literature. This study was
undertaken to collect reliable onsite in-
formation on the quality of treated water
produced by package water treatment
plants.
Results
Turbidity
The six water treatment facilities select-
ed for field research had varied success in
their turbidity removals. Four of the plants
(C, T, W, and P) had uniform, high-quality
source waters, but only three of these (C,
T, and W) consistently met the 1-ntu
effluent turbidity standard. The other
three plants (P, V, and R) met the standard
on fewer than half of the visits made to
them (Table 3).
The performance difficulties of Plants
P, V, and R involved the short detention
times inherent in the design of the treat-
Table 1. Facilities Studied
Site
W
T
V
M
P
C
Model
Year
Neptune
Microfloc
AQ-40
1973
Neptune
Microfloc
AQ-40
1973
Neptune
Microfloc
AQ-40
1976
Neptune
Microfloc
AQ-112
1972
Neptune
Microfloc
Water Boy
1972
Permutit
Permujet
1971
Design
Flow Population Served/
Rate No. of Meters
fgpm)
200 1500/552
200 WOO/360
200 ~~/423
560 — -/1 680
100 —-/411
200 State park
Average
Volume
Per Day
(gal)
110,000
78,000
72,000
330,000
82,000
57,000
Group
Served
City
City
PSD*
PSD*
PSD*
State
park
Type of
Distribution
Pipe Used
PVC
PVC cast iron
asbestos cement
PVC
PVC
PVC
Asbestos
cement
Source
Surface
impoundment
Surface
impoundment
River
River
Surface
impoundment
River
*PSD - Public Service District
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Table 2. Treatment Process Characteristics
Pre- Rapid Mix Flocculation
Site
W
T
V
M
P
C
Table 3.
Chemical
Addition
Cl, alum.
soda ash
Cl, alum.
soda ash.
poly
Cl, alum.
soda ash.
poly
Cl, alum.
soda ash.
poly
Cl, alum.
soda ash.
carbon
(summer)
Cl, alum.
soda ash.
poly
Type d. t
{sec.)
In pipe 3
In pipe 3
In pipe 3
Chamber 30
Chamber
not used
In pipe
Type
Paddle
Paddle
Paddle
Paddle
Paddle
d.t
(min.j
12.8
12.8
14
10
10
Sedimentation
Type Loading
(gpd/fP)
Tubes
Tubes
Tubes
Tubes
Tubes
100
100
100
100
150
Upflow solids contact
2hr. d.t.
rise rate
- 1 gpm/ft2
Filtration
Media Rate notes
(gpm/ft2j
Mixed 5
anthracite 18 in
silica sand 9 in
garnet sand 3 in
Mixed
same as above 5
Mixed 5
same as above
Mixed 5
same as above
Mixed 5
same as above
Silica sand 24 in 2
Poly added
before
tubes
Post soda
ash
Post sodium
hexameta-
phosphate
Soda ash
added
before
filtration
Plant Turbidity Values (ntu)
Plant C
flaw
8.5
6.2
1.2
1.6
2.2
4.0
12.6
5.2
2.2
Clearwell
Effluent
0.3
0.2
0.3
0.1
0.1
0.1
0.7
0.2
0.2
Plant W
Clearwell
Raw Effluent
0.9
5.0 0.3
4.2 0.4
19.0 0.8
9.2 2.0
1 1.5 0.3
12.0 0.2
1 1.0 0.3
29.7 0.9
12.8 0.2
Plant T
Raw
10.0
8.0
6.0
3.2
3.2
3.2
5.8
10.4
3.4
Clearwell
Effluent
1.9
0.2
0.4
1.1
0.2
0.2
0.2
3.2
0.7
Plant V
Raw
4.0
12.0
* __
35.0
*42.0
"10.0
"90.0
"28.0
"19.0
*47.0
"13.0
* 8.0
* 6.0
*> 100.0
"60.0
24.0
13.0
2.7
1.2
3.3
Clearwell
Effluent
1.8
2.8
9.6
1.5
2.0
2.4
8.5
5.4
0.3
1.2
0.8
0.3
0.3
0.5
0.5
1.2
0.3
1.2
1.0
0.5
Plant R
Clearwell
Raw Effluent
0.2
39.0 3.8
40.0 2.6
27.0 2.4
6.0 1-2
3.8 0. 1
73.0 1 1.0
* 3.6 0.1
3.8 0.3
6.0 0.5
*70.0 16.0
*25.0 3.4
*> 100.0 55.0
*>100.0 31.0
* 8.5 2.2
4.3 0.4
* 4.0 1.0
* 9.6 1.9
19.1 1.1
64.0 6.9
8.2 1.0
Plant P
Clearwell
Raw Effluent
12.0 0.8
4.4 2.4
7.0
3.5 1.5
2.0 0. 1
1.2 0.5
15.6 9.7
3. 1 2.2
17.2 1.9
*Averaged Values for Day
ment units, the lack of skilled operators
with sufficient time to devote to treatment,
and (in the cases of V and R) the variability
and quality of the source water.
The stream source quality at Plant V was
quite variable with the turbidity often ex-
ceeding 100 ntu. The first eight daily
values obtained at this site over a 4-month
period did not comply with the 1-ntu
standard. But data indicated much im-
provement after operational methods were
upgraded and needed maintenance was
performed. Daily average turbidities for
the last 12 sampling days over an 8-
month period met the turbidity MCL, al-
though some values exceeded the limit
Before the changes in maintenance and
operation, this plant did not consistently
reduce influent turbidities of 35 to 50 ntu
to adequate levels. But afterwards, ef-
fluent turbidities were less than 1 ntu even
when influent turbidities increased from
17 to 100 ntu within a 2-hour period.
Plant R difficulties in turbidity removal
were also caused by highly variable source
water turbidities and inadequate staff time.
This site had influent turbidity levels that
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ranged from 3.5 to> 500 ntu. According
to product literature and a manufacturer's
representative, these peaks could not be
adequately treated at the design capacity
of the unit In fact both Plants V and R
caused State health department engineers
to voice reluctance about approving plans
for future installations of similarly designed
units with such highly variable stream
sources. Nonetheless, even with influent
turbidities of less than 30 ntu, the plant
did not produce an effluent below 1 ntu
because of inadequate operator skill.
Though Plant P had a reservoir as its
source and thus showed consistently low
influent turbidities (1 7.2 ntu maximum),
effluents exceeded the 1 ntu limit in six
out of the nine samples taken. This poor
record was traceable to lack of operator
attention. Though the plant operated an
average of nearly 14 hours per day, the
operator was present for no more than 2
hours.
Plants C, W, and T met the turbidity
requirements on nearly all occasions:
Plant C effluents measured 1 ntu at every
sampling. Plant W exceeded the limit
once, and Plant T failed to meet the MCL
twice. At Plant T, two high effluent turbid-
ities of 1.9 and 3.2 ntu were measured
and found to be caused by a pump failure
and a distribution system problem requir-
ing extensive operator attention. All three
facilities had low-turbidity sources (1.2 to
29.7 ntu) and high-quality operators.
Total Coliforms and Standard
Plant Counts
Total coliform determinations for treat-
ed water from all six plants showed no
coliforms, with the exception of one distri-
bution system sample taken at a residence.
Total coliforms in raw water samples from
the six water treatment plants varied up to
10,000/100 mL. Two of the three facili-
ties using river sources had the highest
total coliform densities, with typical raw
water levels between 1,000 and 10,0007
100 mL The plants using impoundments
for their sources had raw water total
coliform densities approximately one or-
der of magnitude lower than this range.
The standard plate counts for treated
water from all six facilities were low: 30
percent of the samples had counts that
were lower than 1/mL, and 68 percent
showed densities of 10/mL or lower. The
highest standard plate count was 2700/
ml.
The low standard plate counts and the
absence of coliforms in the treated water
examined indicate that all six water treat-
ment facilities produced adequately disin-
fected water.
Inorganic Contaminant
The chemical analyses performed by the
U.S. Environmental Protection Agency
(EPA) for inorganic contaminants listed in
its drinking water regulations show that
no maximum contaminants levels (MCL)
listed in the primary regulations were
exceeded in any influent and effluent
samples. Five effluent samples had
manganese concentrations greater than
the secondary MCL's, and two treated
water samples exceeded the recommend-
ed secondary MCL for iron. Results of the
effluent and distribution system analyses
revealed that 15 of 18 treated water
samples exceeded sodium levels of 20
mg/L
Note that the operators of these facili-
ties were not trying to control sodium,
manganese, or iron at the time these
samples were collected. Their major con-
cerns were turbidity removal and ade-
quate disinfection.
Trihalomethanes
Four of the six plants studied had at
least one treated water instantaneous tri-
halomethane (THM) sample with a total
THM concentration greater than 0.10
mg/L. The small size of these water
systems precludes them from having to
comply with any present THM regulations.
The point of chlorination and often the
large free chlorine residuals (>2. mg/L)
detected in the treated water contribute to
these high THM levels. All six of the plants
were originally equipped with pre- and
post-chlorination capabilities, but all of the
plants practiced prechlorination during
the study.
General Observations
The three facilities that were most suc-
cessful (sites C, T, and W) had competent
operational staffs who devoted sufficient
time to water treatment All had knowledge
of water treatment or great familiarity with
their plants and dedication to their work.
These plants were characterized by fre-
quent monitoring of the influent and ef-
fluent quality. Improvement of the water
quality at site V came from increased
maintenance and more frequent sampling
of water through the plant The staff at site
R lacked adequate knowledge and time to
devote to water treatment Distribution
system maintenance requirements kept
this staff from properly maintaining and
monitoring their plant The small per-
centage of time spent by the operators at
site P resulted in poor effluent quality,
even though the influent turbidity was
quite low.
Conclusions
Package water treatment plants manned
by competent operators can readily treat
the turbidity and bacteria of surface waters
that have fairly consistent quality. Reser-
voirs have proved satisfactory for provid-
ing acceptable influent waters.
Package plants using variable sources
(e.g., streams) require a high degree of
operational skill and near constant vigi-
lance by the operators. But regardless of
their source quality, all package plants
require a minimum level of maintenance
and operational skill. Lack of this mini-
mum skill and attention precludes con-
sistently successful turbidity removal,
regardless of the influent quality.
Most package plants are located in rural
or remote areas where it may be difficult to
hire well trained operators. Small com-
munities may have to greatly increase
salaries to attract well qualified operators.
The full report was submitted in ful-
fillment of Cooperative Agreement CR-
806449 by the University of Cincinnati
underthesponsorshipoftheU.S. Environ-
mental Protection Agency.
James M. Morand and Matthew J. Young are with the University of Cincinnati,
Cincinnati, OH 45221.
Thomas J. Sorg is the EPA Project Officer (see below).
The complete report, entitled "Performance Characteristics of Package Water
Treatment Plants," (Order No. PB 83-161 018; Cost: $11.50, 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:
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
. S. GOVERNMENT PRINTING OFFICE: 1983/659-095/1905
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Environmental Protection
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Information
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