CRYPTOSPORIDIUM AND THE MILWAUKEE INCIDENT
(U.S.) ENVIRONMENTAL PROTECTION AGENCY, CINCINNATI, OH
JUL 94
U J. HEPAKTMBIT OF COMMBICE
Nriofwi Technical bitonmilon Swvto*
-------
EPA/600/A-94/251
Mil WAHKI.I INilDI Nl
Cryptoaporidium and the Milwaukee Incident
Kim R. Fox and Darren A. Lytle'
Introduc|.ion
In early 1993, Milwaukee, Wisconsin reported a sharp
increase in the number of dia.rrt.ea patients and shortages
of over the counter drugs for diarrhea control at local
pharmacies. The increase in diarrhea was determined to be
caused by the organism Crvptosaoridtun. Preliminary
investigations conducted by St,»te and City officials
suggested that the drinking wa':er nay have been partially
responsible for distributing the organism around
Milwaukee.
On April 6, a doctor ordered a parasitic analysis on
a patient's fecal specimen. Cryptosporidium was detected
in the tecil smear. At that tine, the local and state
officials were notified of the Cryptosporidimn detection.
A concurrent survey of diarrhea cases in local nursing
it^mes indicated that rt^identr in nursing homes in the
souti, >rn part of the city wer«» fourteen times more likely
to nave i,*d diarrhea than theme in the northern part of
the city, jr addition to the nursing home survey,
turbidity problems at the southern water treatment plant
also implicated drinking water and this plant as being
suspect in the crypto^poridiusis outbreak (Figure 1). At
that point, the souther*; (Howard) plant was shut down and
all water for Milwaukee w«* supplied by the northern
(Linwood) plant under a bo. 1 water order.
The closure of the How.ird Water Treatment Plant, the
boil water order, the Magnitude of the number of reported
diarrhea cases, and the medi^ attention, all helped to
en
8S
«B
o
2.S
1 .S
o.s
Date
Figure 1. Diarrhea Onset & Max. Filter Turbidity
Steel Crib
InUk*
Sedimentation
Coagulation Ba,sms Filters
Basins
East CleatweU
15 MG
Texas Ave.
Pumping Station
Rapid mix
0.127 MG
Weir Room
West Ciearwell
20 MG
i
'Environaental Engineera, o.s. Environmental
Protection Aqenry, Drinking Hater Kesearch Division, 26
H. NtK Dr., Cincinnati, Ohio 4S26S.
Figure 2 Howard Avenue Water Treatment Plant
-------
52
WATER AND WAST*WATER TREATMENT
MH.WAIIKM: INIIIH.NI
focus water utility personnel, engineers, scientists,
government officials, and rule-making bodies onto this
waterborne outbreak. Follow up surveys have indicated
that as mrny as 403,000 people may bave been ill during
the Milwaukee incident (Edwards 1993).
Cryptosporidium is a protozoan that if ingested by a
healthy adult human Bay cause some discomfort such as
that felt with stomach flu, however, it can be life
threatening to others such as infants, AIDS patients and
the elderly. Research has shown that Most surface waters
are contaminated with this parasite (LaChevallier 1991).
Crvptosporidium oocysts are very resistant to
chiorillation and, therefore, their effective removal fro*
surface waters is highly dependent on the operation of a
filtration facility.
During the initial stages of the outbreak, the City
of Milwaukee requested the assistance of the U.S.
Environmental Protection Agency (EPA) to provirte
technical assistance. A team fro* the EPA's Drinking
Water Research Division (DWRD) familiar with filtration
processes and with the removal of Crvptoaporidium oocysta
by filtration went to Milwaukee. The teasi concentrated
its efforts on evaluating the operational and monitoring
data available from tha southern Howard Avenue Hater
Treatment Plant. The goal was to assess how (from an
engineering standpoint) Crvptoaooiidium may have passed
the water treatment facility.
As part of the EPA Assistance, the team called upon
research previously sponsored or conducted by the DWRD on
removing Cryptosporidiosi from drinking water. This
research Included both extramural and in-house laboratory
and pilot plant filtration studies. Both the in-house
studies and the field studies have indicated that good
turbidity and particulate removal is necessary for good
removal *>f Crvptosporidium from drinking water.
Plant Inspection
The source water for Milwaukee, Wisconsin, is Lake
Michigan (City of Milwaukee 1992). The city's water is
treated at two water treatment facilitiesi the northern
situated Linwood treatment plant and the southern Howard
treatment plant. Both treatment facilities treat Lake
Michigan water by conventional water treatment processes
(coagulation, sedimentation, filtration, and
disinfection). The Linwood facility has a water
treatment capacity of 215 million gallons per day (MGD)
and tha Howard treatment facility has a filtration
capacity of 100 MGD. During typical operation, the
Linwood plant supplies the northern 2/3 of the water
district. The Howard plant supplies the remaining 1/3.
iTje mixing zone exists in the distribution system
between the two treatment facilities, but the general
flow of water is northern or southern. The initial
investigation linked the cryptosporidiosis outbreak to
drinking water treated at the Howard treatment, facility,
resulting in temporary shutdown of the facility. The EPA
team focused its efforts on understanding the operation
of the Howard treatment plant.
The Howard Plant is a conventional coagulation,
sedimentation filtration facility (Figure 2). A complete-
description can be found in Fox and Lytle (I993b). Alun
(aluminum sulfate) was the coagulant used until August of
•1992. In August of 1992, the facility switched to
polyaluminum chloride (PACL). The switch to PACL was done
with the belief that a benefit of higher finished water
pH for corrosion control would be met as well as reduced
sludge volume and improved coagulation effectiveness in
cold raw water conditions. Before switching to PACL, trie-
city consulted with the chemical «~ -ifaeturer, Wisconsin
DHR, and other communities receiving Lake Michigan water
and using PACL.
In the time frame immediately preceding March 1993,
the Howard Plant (BWTP) was consistently producing a low
effluent turbidity water (daily averages of 0.1 HTU or
less). During the period of March 18 thru April 8 (plant
was shut down April «), the effluent turbidity from the
BMTP was highly variable and ranged from between 0.1 and
1.7 NTO (Figure 1). The team was asked to look at what
caused the higher turbidity levels to occur. At all
timss during this period, effluent water samples were
negative for coliforms and met the Wisconsin >NR
regulations for turbidity.
The HWTP receives a highly variable quality of
influent water (from Lake Michigan) to be processed
through the plant. During the time period of March 18
through April 8, the raw water turbidity levels ranged
from 1.5 to 44 HTU. Total coliforms ranged from
-------
WATER AND WASTEWATER TREATMENT
and order controlling trearjnent. Throughout the period,
cocgultmt dose adjustments were continuously being made
to Meet the demands of raw water quality,
Although the coagulant doaagea were being adjusted,
filter effluent turbidities on several occasions exceeded
turbidity values that were achieve^ in previous months.
As the coagulant doses approached *?hat might be optimum
dosages for the particular raw water conditions,
improvements in settled water turbidities antl filter
effluent turbidities were achieved. This pattern «»as
sec
-------
56
WATER ANU WASTEWATER TREATMENT
several experiments uslag various grades of diatcmaceous
earth (Dl) on • precoat filter. Observed oooysts
removals exceeded three log resnval for all runs, but
removals were dependent or DE grade. The larger the
grade, the sore oocysts found in the effluent.
leta potential measurements were aade in DWRD labs
using clean suspensions of Crvptosporidiam oocysts (both
•oris and parvuB) diluted into a river water that had
been filtered through Ifis. membrane filters. Tests were
conducted to evaluate variables such as age of oocysts,
storage solution, and pB of suspanslon fluid on oocysts.
Nuris oocysts Mere highly variable in regard to teta
potential as the charge increased *rosi -21 aw to -1.8 nv
as the pi was lowered from l".0 to 1.6 (smris oocysts
were not stored in dichromate). Muris oocysts stored in
dicbrostate had a considerable greater charge Magnitude
than th:>se in clean suspensions (-31.1 versus -20.1 av,
respectively). The parvusi oocysts displayed a change
fru» -11.8 BV (in clean suspensions) to -25.2 «v in
suspensions stored in dicbromate. In one study, the
fecal Material from a calf was stored in dichromate for
twelve hours nntil the material ROCId be processed the
next day. The oocysts were harvested and stored without
dicbrostate. Twenty-four hour* after preparation, the
•Masurad chare* was -6 BV. The suspenkion was Monitored
for eight days and the cbar?'J gradually changed to -14.1
siv. There were not enough oocysts to continue the study
to determine If the charge would recover to -17.8 mv seen
with most fresh oocyets. Seta potential studies by Ghosh
showed values S snr more negative than the results in the
EPA '.ests with preserved oocysts.
Discussion
The prelijuc. **ts have indicated that Boat
filtration sy»tems ffactive ia ramoving greater than
2.5 logs of ooeystp ideal operating conditions.
These tests for the m. t have been done with oocysta
preserved In dichrostate .... ith formalin fixed oocysts.
Both the preservation solution and the fiiratlan fluid
have shown an effect on the mwasared seta potential and
My have an effect on the rigidity of the organise. The
few studies complated with fresh oocysts ha**e shown lean
effective removal bat sore work ia planned. Several
surveys in the literature (LeChevallier 1991} have
indicated that oocyatr are passing through sane filter
plants. The passage of oocysts Bay indicate that fresh
(or untreated) oocysts Bay be Bore difficult to remove
than those that are pretreated by SOBS Banner. The
preservation processes Bay affect thai physical
characteristics of the oocysts and Bay Bake them more
susceptible to filtration processes than those in the
MKt-K INCIDLNI
natural environaent.
In order to achieve good reduction in turbidity at
all times, stringent controls on coagulant/flocculant
dosages are required. This control could b« at—«ated 01
done by operator attention and that determination would
be at the discretion of the water utility. Subtle
changes in bffluent turbidity front a filtration plant n
FOE, Kim R. and Lytle, Darren *. (1993b) "The Milwaukee
Cryptosporidioais Outbreaks Investigation ^nd
Recommendations', Proceedings AHH* Water Technology
Conference, Miami, Florida.
Ghosh, M.M., et al. (1989). "Field Study of Gicrdia and
Crvptosporidiua Removal from Pennsylvania Surface Waters
by Slow Sand and Diatomaceous Earth Filtration".
Environmental Resources Research Institute.
LeChevallier, M.H., et al. (1991).
CrvptosporidiuB in Hater Supplies".
Foundation. XSBB 0-89867-569-3.
"Giardia and
AHWA Research
-------
TECHNICAL MPOftT DATA
/PIMM *Mrf AutmcriM* cm mt w«r«r w/
RiPOPIT NO.
EPA/600/A-94/251
TITLE ANOSUSTITLB
CRYPTOSORIDIUH AND THE MILWAUKEE INCIDENT
I. REPORT OATI
July 1994
>. PIRPORMINO ORGANIZATION COOI
RREL/OWRO
AUTHORISI
Kin R. Fox and Darren A. Lytle
I. PERFORMING ORGANIZATION P.EPOPT NO.
PERFORMING ORGANIZATION NAMi AND ADDRESS
DRINKING WATER RESEARCH DIVISION
U.S. EPA
26 W. MARTIN LUTHER KING DR.
CINCINNATI, OH 45268
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT SO.
In-house
13. SPONSORING AQINCV NAMt AND ADDRESS
Risk Reduction Engineering Laboratory—Cincinnati, OH
Office of Research and Development
U.Sl Environmental Protection Agency
Cincinnati, OH 45268
13. TYPI 0^ REPORT AND PERIOD '.OVEREO
Published Paper
. SPONSORING AGf NCV COOI
EPA/600/14
is. SUPPLEMENTARY NOTM project Officer = Kim R. Fox (513) 569-7820; Proceedings of the
1994 National Conference on Environnental Engineering, "Critical Issues in Water and
Wastewater Treatment, Boulder, CO, 7/11-13/94, p;50-57 _
6.
In March and April of 1993, Milwaukee, Wisconsin reported a very large Increase
In the number of diarrhea patients and shortages of over the counter drugs for
diarrhea control at local pharmacies. Preliminary Investigations conducted by State
and City officials suggested that the drinking water nay have been partially responsi-
ble for distribution Cryptosporldium around Milwaukee. In addition to turbidity data,
a survey of diarrhea cases In local nursing hones Implicated the Howard Water
Treatment Plant. A team of Investigators from the EPA's Drinking Water Research
Division (DWRD) assisted with the Investigation. This paper describes the approach the
EPA team took 1n evaluating the effectiveness of the water treatment facility to
remove partlculates, Including a discussion of the key operational data and a
description of what w=s observed at the treatment facilities. Research Including
both extramural and In-house 'laboratory and pilot plant studies for Cryptospor1d1um
removal Is also discussed. A brief summary and discussion of this data Is presented
In this paper. "
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDCNTIPIERS/OPEN E»«OED TERMS
c. COSATI Field/Group
Cryptospor1d1um
Milwaukee
Drinking Water
Filtration
Zeta Potential
Cryptosporidiosls
21. NO. Of 'AGES
10
IS. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (Ttttt Report!
unclassified
20. SECURITY CLASS (TMlfMgri
unclassified
22. PRICE
IPA firm 2220-1 (!»•». 4-77) PHCVIOU* COITION is OBSOLBTC
------- |