United States
Environmental Protection
Agency
Municipal Environmental
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-84-119Aug. 1984
Project Summary
Isolation, Characterization, and
Identification of Microorganisms
from Laboratory and Full-Scale
Landfills
Jean A. Donnelly and Pasquale V. Scarpino
Studies were conducted to determine
whether solid wastes in landfills contain
human pathogens and whether these
organisms survive landfill conditions and
drain out with the leachate. Pilot-scale
and commercial-sized landfill operations
were evaluated, along with laboratory-
sized lysimeters containing municipal
solid waste, hospital waste, and sewage
sludge.
Total and fecal conforms in initial
leachate tended to decrease rapidly
with time, whereas the numbers of
fecal streptococci decreased at a slower
rate. These indicator organisms were
generally below detectable limits in
leachates after a year, but specific
microorganisms (including pathogens)
could be isolated from these leachates
and from the solid wastes.
This Project Summary was developed
by EPA's Municipal Environmental
Research 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
One of the concerns of landf illresearch-
ers is whether or not pathogenic microor-
ganisms present in solid wastes are able
to survive landfill conditions and drain
with the leachate through the underlying
soil to groundwater or to surface waters.
To demonstrate how such migration
could occur, it is first necessary to
determine that municipal solid wastes
contain infectious microorganisms, then
to evaluate the evidence for their survival
both in newly deposited landfills and
those several years old, and finally to
show that microbes could pass to
groundwater below. If these microogan-
isms could survive for long periods of time
in the landfill, they might be resistant
enough to survive in leachate leaving the
landfill and would be able to pollute the
surrounding environment. Consequently,
the working hypothesis for this study was
that the pathogenic microorganisms
present in solid waste could survive
landfill conditions and can drain out with
the leachate and contaminate the sur-
rounding waters.
Experimental Approach
To carry out these objectives, the
following experimental approach was
taken: Methods were developed (Phase I),
simulated landfills were studied (Phase
II), and field studies were conducted on
full-scale landfills (Phase III). Phase I
examined problems such as the freezing
of leachate samples, leachate toxicity,
most probable number (MPN) test,
nonspecificity, and bacterial stress
resulting from leachate toxicity. Methods
development involved (1) improving a
Salmonella enrichment medium, (2)
concentrating leachate for the enumera-
tion of Mycobacterium, (3) a comparison
of eight streptococcal enumeration
procedures, (4) adapting clostridial
enumeration procedures, and (5) devel-
oping methane-utilizing and methane-
producing bacterial procedures. In Phase
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II, six lysimeters were constructed and
placed at the University of Cincinnati to
test the survival of pathogens in various
combination of hospital, sewage sludge,
and municipal solid wastes. After 2 to 3
years, these six lysimeters were opened
and the solid wastes within were examined
for surviving fecal indicator bacteria and
pathogens. In addition, leachates were
collected and examined at experimental
lysimeters at Boone County, Kentucky, and
at the EPA Center Hill Facility in Cincin-
nati, Ohio. In Phase III, the leachatefrom
a commercial landfill was used to isolate
streptococci, salmonellae, mycobacteria,
and clostridia. Also, closure studies at the
Boone County landfill yielded an oppor-
tunity to compare similar lysimeter
studies made previously. Finally, assays
for methane-utilizing and methane-pro-
ducing bacteria were made on leachate
and on solid waste from this same
landfill. Tables 1 and 2 describe the
landfill sites and lysimeters.
Methods
Methods selected for this work were
initially derived from those in current use.
However, these methods did not always
work efficiently and were occasionally
nonspecific and imprecise. Some of the
problems encountered included the
following:
1. Growth of fewer microbial colony
types from leachate following labora-
tory freezing of leachate samples,
2. Problems with pure culture isolation,
3. Lack of a stock culture storage
system,
Table 2. Description and Purpose of Laboratory Lysimeters
Number Contents**
Purpose
B
C
D
E
Sewage sludge
Municipal solid
waste plus
sewage sludge
Municipal solid
waste
Municipal solid
waste
Municipal solid
waste plus
hospital waste
Hospital waste
To provide a microbial control for the sewage sludge used
in Lysimeter B.
To determine the impact of municipal sewage sludge ad-
ditions on the rates of decomposition and formation of gas
leachate. Also, to elucidate microbial changes in the lea-
chate.
To provide a control for microbial numbers and species
Same as Lysimeter C.
To determine the impact of pathogens on municipal so/id
waste and the ability of pathogens to survive landfill con-
ditions
To provide microbial control for the hospital waste used in
Lysimeter E.
"208.2 liters in each 55 gal drum.
^Lysimeters maintained at 20°C in a constant-temperature room.
4. No growth in higher concentrated
leachate (some growth did appear in
more dilute portions),
5. Nonspecific tests,
6. No isolation of pathogens from
samples containing sewage sludge
and other wastes,
7. Variations in streptococci concentra-
tions detected by two or more
methods,
8. Lack of comparability of MPN tests
with plate counts, and
9. Bacterial stress.
Short-term studies were carried out to
analyze the methods and to improve their
performance. Though not all of the
problems were solved, the analyses
strongly suggest that further improve-
ments would greatly increase the patho-
gen and fecal indicator identifications
Results and Discussion
Boone County and Center Hill
Simulated Landfills
Leachate samples were examined
periodically from the Boone County and
Center Hill simulated municipal solid
waste landfills to determine the fecal
indicator levels, plate counts, and the
identification of pathogenic microorgan-
isms. The fecal indicator and plate count
assays are presented in Table 3. The
results show that the total and fecal
coliforms had died out, but the strepto-
cocci remained viable. The eosin methy-
Tablet. Landfill Sampling Sites
Leachate
or
Solid Waste
Landfill Abbreviation
Commercial.
Full-Scale
Operational
Boone
County,
Kentucky
Boone
County.
Kentucky
Center Hill,
Cincinnati,
Ohio
University of
Cincinnati,
Cincinnati.
Ohio
CL
BC 1
BC2
through 5
CH 1
through 19
A
through F
Dimensions
and
Placement
600 Acres
in Soil
30' x 149'
x8.5'
in soil
12' x 6'
Steel
Cylinders
in Soil
12'x6'
Steel
Cylinders
2'x2'
in Steel
55-gal
Drums
Solid Waste Added
Type
Municipal,
hospital
commercial
Municipal
Municipal
Municipal.
sewage sludge,
industrial
Municipal,
sewage sludge,
hospital
Amount
Millions
of
Tons
435 Tons
2 Tons
2 Tons
150 Ibs
Date
Prepared
1954
1971
1972
1974.
1975
1978
Date of
Last Waste
Deposit
Daily
(active)
June 1971
(inactive)
August 1972
(inactive)
Nov. 1974
& April. 1975
(inactive)
August 1978
(inactive)
-------
Table 3.
Microbial Counts* From Landfill Leachate
Landfills (Lysimeters)
Quantitative
Tests
MPN/IOOml:
Total coliforms
Fecal coliforms
Fecal streptococci
Agar plate counts, CFU/100 ml:
Blood-aerobic
Blood-anaerobic
Brain heart
Eosin methylene blue
Inhibitory mold**
KF streptococcal
Mycosel**
Sabouraud**
Tellurite
Boone
BC-1
16 years)6
<30
<30
1 x 10*
7.3 x 10s
8.0 x 1C?
4.0 x 10s
3.0 x 10s
1.7x 10*
-------
microorganisms in the leachate were
carried out at periodic intervals during a
2- to 3-year period. At the end of the test
period, the lysimeters were opened and
the contents were examined for microbes.
Microbial analyses of the three types of
solid wastes used in the six lysimeters
appear in Table 5. All three wastes had
high levels of total cohforms, fecal
conforms, and fecal streptococci. The
sewage sludge generally showed lower
fungal levels than the others. This result
would be expected because the microbial
population was restricted to those
coming from the digestive tract. The
municipal solid waste, on the other hand,
contained high fungal counts, probably
because it contained wastes from more
sources (soil, trash, and sweepings, for
example).
The ratio of fecal coliforms to fecal
streptococci (FC/FS) was used to deter-
the origin of the wastes (animal or
human). Environmental samples from
human fecal material yield FC/FS ratios
of >4 whereas animal ratios are <0.7.
Sewage sludge resulted in a ratio of 7.27,
indicating a human origin. The ratio in
municipal solid waste was 0.19, which
indicates nonhuman sources, including
animals and vegetation. Hospital wastes
had a ratio of 1.05, an intermediate value.
The microorganisms isolated and iden-
tified from each type of waste are
presented in Table 6. Six of the 15
identified genera are listed as pathogens.
Most of these bacteria are usually found in
feces. Of the six pathogen types listed,
three were found in sewage sludge, five
in municipal waste, and four in hospital
waste. Of the total number of pathogens
isolated from each waste, 6 were from
sewage sludge, 10 were from municipal
waste, and 8 were from hospital waste.
Table 6. Gram-Negative Bacteria Isolated From Solid Wastes Used in the Construction of the
University of Cincinnati Lysimeters
Bacterial Genera
and Species
Bacterial Numbers Isolated from
Sewage Sludge
Municipal Waste Hospital Waste
Oxidase Negative
Lactose Fermenters:
Eschenchia coli
Enterobacter sp.
Klebsiella* sp.
Citrobacter sp.
Subtotal
Non-lactose Fermenters
Serratia sp.
Proteus sp.
Providencia sp.
Salmonella*
Subtotal
Oxidase Positive
Nonfermenters:
AeromonasJ sp.
Flavobactenum sp
Herellea* sp
Mima* sp.
Moraxella* sp.
Pasteurella hemolytica*
Pseudomonas sp.
Subtotal
8
7
3
4
22
4
3
10
3
3
3
10
19
10
1
3
14
2
1
1
+
2_
8
2
6
5
11
24
4
13
1
7,9
17
23
+ None detected.
* These bacteria appear on the Communicable Disease Center (1974) list (i. e.. Classification ofEtio-
logic Agents on the Basis of Hazard).
f A fermenter.
The fecal indicator tests of the leachates
taken over the 2-year span, presented in
Table 7, show that most total coliform
levels and fecal coliform MPN levels had
decreased to <20 MPN/100 ml at the end
of the 13th week, and the fecal strepto-
cocci had disappeared after 104 weeks.
Microorganisms found in the lysimeter
leachate after 2 years are listed in Table
8. These microorganisms should be
compared with those in Table 6. The only
TableB.
Microbial Densities in Three Types of Solid Waste Added to Lysimeters
Type of Test
and Microbe
Fecal indicator test
{MPN /1 00 g)
Total coliforms
Fecal coliforms
Fecal streptococci
Agar plate counts
(CFU/IOOg)
Standard methods
Blood - aerobic
Blood - anaerobic
Eosin methy/ene blue
Inhibitory mold agar
KF streptococcal
Mycosel
Sabouraud
Tel/urite
Sewage
Sludge
2.8 x ro"
2.4 x 10
3.3 x 109
1.7x10
4.1 x 10
29x10
1.5x10
1.0 x 107
3.6 x 107
3.6 x 107
1.4x 10
43 x W7
Hospital
Waste
9.0 x 10
9.0 x 10
86 x W
3.8 x 10
3.9 x 10
2.2 x 10
3 1 x 10
3.8 x 10s
3.0 x W9
7.5 x 10g
3.4 x 10
2.6 x 10s
Municipal
Waste
7.7x10
4.7 x 10
2.5 x 70"
43 x 10"
3.6 x 70"
3.5 x 70"
3.4 x 10
6.9 x 709
42 x 10
1.6x 709
25 x 70"
66 x 709
surviving pathogenic Gram-negative
bacillus was Acinetobacter sp. Several
fungi were found (Phialophora sp.,
Monosporium sp., Aspergillus niger), but
they were not on the CDC list of
hazardous agents. These fungi can be
found in pathogenic lesions, however.
Final assays were made on the contents
of the six lysimeters to determine the
fecal indicator levels, plate counts, and
the pathogen levels (e.g., Clostridium,
Salmonella, and Mycobacterium). Two
lysimeters were examined after 2 years,
and four were examined after 3 years. An
examination of the surface of the waste in
lysimeters UC-B through F indicated that
the bentonite packed around the edge of
the waste and the sides of the lysimeter
were intact. As expected, it kept the water
away from the sides of the lysimeter and
allowed only the center of the deposited
solid waste to be moistened by the weekly
water additions. Lysimeter UC-A, the
sewage sludge lysimeter, had no bento-
nite to direct the water flow. There the
sludge had separated from the sides of
the lysimeter by at least 1 cm, and it was
obvious that the water had run down into
a pocket made between the sludge and
the lysimeter wall. The marks made on
the wall of the lysimeter indicated that the i
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Table 7. Microbial Concentrations in Leachates Obtained From the UC Laboratory Lysimeters 13 and 104 Weeks After Construction
UC Laboratory Lysimeters
A. B, MSW
Quantitative sewage plus sewage C
Tests sludge sludge MSW
MPN/100 ml:
Total conforms:
13 weeks 20 86 40
104 weeks <2 <2 <2
Fecal conforms:
13 weeks <20 <20 <20
104 weeks <2 <2 <2
Fecal streptococci:
13 weeks 4.9x10* 1.6x10" 3.5x10?
104 weeks <2 <2 <2
Agar plates. CFU/IOOml:
Blood-aerobic:
13 weeks 1.9x107 1.2 x 10e 6.8 x 107
104 weeks 1.2x10* 1.3x10* 1.6x10*
Blood- anaerobic:
13 weeks 6.3 x 10s 1.1 x 107 8.0 x 107
104 weeks 1.2x10* 3.3 x 10s 3.2x10*
Standard methods:
13 weeks 1.4 x 10* 5.4 x JO7 7.9 x 1O7
104 weeks 1.0 x 10s 1.4 x 10* 1.2 x 10B
Sabouraud:
13 weeks 2.2 x107 4.9 x 107 2.2 x 107
104 weeks 3. 1 x 10* 4.2 x 10s 4.2 x 10s
Tellurite:
13 weeks 1.1 x 10* 1.6 x 10* 7.8 x 10*
104 weeks 4.0 x 10* 2.9 x 10* 4.0 x 103
TableS. The Identification of Leachate Microorganisms Taken From the Lysimeters During the
100th Week of Operation
Lysimeter Microbial Identification Number of
Designation Group Name Cultures
UC-A Bacteria Acinetobacter sp. 2
Alcaligenes faecalis 2
Corynebacterium acquaticum 1
Corynebacterium sp. 1
Pseudomonas sp. 7
Fungi Monosporium sp 1
Phialophora sp. 1
UC-B Bacteria Bacillus sp. 2
Corynebacterium sp. 4
Fungi Aspergillus niger 1
Monosporium sp. 1
Yeast 1
UC-C Fungi Yeast 1
UC-D Fungi Penicillium sp. 1
UC-E Fungi Yeast 1
UC-F None None 0
sludge had settled about 3 cm during the 3 did not appear to have decomposed or
years. changed to any great degree. However,
The compactness of density of the the compacted waste tended to become
waste was also examined. This param- soil-like 30 cm from the surface of the
eter varied with the type of waste. The waste that is, it was gritty and had a
sewage sludge lysi meter waste appeared darker hue compared with the waste on
to have the consistency of pudding. The the surface.
waste was easily scooped out during the The results of the assays on the solid
sampling process. The other waste waste samples contained within the UC-F
ysimeters were compacted, and all (hospital waste) and UC-D (MSW) lysi-
Bquired considerable digging to remove meters, which were opened after 2 years,
the samples. For the most part, the waste are listed in Tables 9 and 10. Levels of
E. MSW F.
D plus hospital hospital
MSW waste waste
<20 <20 <20
<2 <2 <2
<20 <20 <20
<2 <2 <2
2.3 x 10s 2.9 x 10* 7.9 x JO2
<2 <2 <2
2.9 x 10* 7.6 x 10* 1.2x 107
1.4x107 9.5 x 10s 3.3 x 105
(
5.6 x 107 3.1 x 107 2.1 x 10*
4.0 x 107 1.7 x 10* 2.7 x 10*
3.1x10* 1.5x107 6.3x10*
2.2 x 107 2.8 x 107 3.1 x 10*
6.6 xlO7 4.6 x 107 5.2x10*
1.7x10* 3.5 x 10s 1.9x10*
4.5 x 107 1.7 x 10* 5.9 x 10*
1.6x 10* 6.4 x 10* < /O3
indicator organisms were higher in the
upper solid waste layers than in samples
taken at lower depths. An association
appears to exist between microbial
numbers and pH, especially in the MSW
lysimeter. The bacterial concentration
generally decreased with the decrease in
pH levels. These results demonstrated
that the coliforms had not died as was
indicated by the low fecal indicator levels
in the leachate; rather, they had survived
for more than 2 years. The lower pH in the
lower sections of the solid waste deposited
within the lysimeters may have resulted
from the carbon dioxide given off during
the microbial fermentation of the waste
materials. Pathogens isolated directly
from the wastes were Clostridiumbotuli-
num, Clostridium tetani, Klebsiella sp.,
Acinetobacter sp., and Monosporium
apiospermum.
Commercial and Full-Scale
Lysimeters
Leachate samples were examined for
fecal indicator levels and plate counts at an
active commercial landfill and an inactive
full-scale landfill at Boone County,
Kentucky (see Table 1 ). The results are
included in Table 3. The fecal indicator
levels, (i.e., the total coliforms, fecal
coliforms, and the fecal streptococci)
from the Boone County leachate were
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Table9. Microbial Levels in Solid Waste From a 2-Year-Old Lysimeter Containing Hospital
Waste
Duantitativf-
Tests
MPN/100 g (100 ml):
Total coliforms
Fecal coliforms
Fecal streptococci
Agar plate counts
CFU/100 g (100 ml):
Standard Methods
Chocolate /aerobic)
Chocolate (anaerobic)
PEA* (aerobic)
PEA (anaerobic) \
Blood (aerobic)
MacConkey (aerobic)
MacConkey (anaerobic)
IMA
M-enterococcus
Sabouraud
Tellurite
Chemical Tests
PH
Conductivity, iimho/cm
Moisture, %
Lysimeier co/
10 cm
2.2 x 10"
20
3.4 x 102
6.0 x 107
4. 1 x 107
1 x 107
2. 1 x 10s
5.4 x 10e
1.7 x 10s
9.3 x 106
1.2x 105
4.2 x 10s
1.2x 10*
3.9 x 107
2.0 x 10*
5.15
1519
61.5
mems ai uescenaing
20 cm
9.2 x 103
<20
1.1 x 103
6.0 x 10s
4.8 x 10s
7. 1 x 107
2.9 x 10s
5.8 x 10*
1.1 x 706
4.2 x 10*
<1 x 103
5x103
< 1 x 103
1.7 x 10s
<1 x 103
5.2
874
58.0
Levels
30 cm
1.6x 10*
<20
70
4.3 x 10*
8.2 x 10*
8.0 x 10s
3. 1 x 103
1.6x 10s
2.7 x 10*
6.0 x 103
<1 x 103
1.6x 10*
<1 x103
1.2x 10s
<1 x 103
4.95
826
61.9
* Phenylethyl alcohol agar without blood.
Table 10.
Microbial Levels of Solid Waste From a 2- Year-Old Lysimeter Containing Municipal
Solid Waste
Quantitative
Tests
MPN/100 g (100 ml):
Total Coliforms
Fecal Coliforms
Fecal Streptococci
Agar plate counts.
CFU/ 1 00 g (1 00 ml):
Standard Methods
Blood Agar (aerobic)
Blood Agar (anaerobic)
PEA* (aerobic)
PEA (anaerobic)
MacConkey
IMA
Sabouraud
Tellurite
Chemical Tests:
PH
Conductivity, umho/cm
Moisture, %
* Phenylethyl alcohol agar
Lysurieter oof
10 cm
1.3x 103
90
7. 1 x 10*
1.0 x 10*
2.5 x 10*
spreader
2.7 x 10*
3.5 x 107
<1.0x 103
4.0 x 103
<1.0 x 103
3.5 x 107
7.1
1780
69.65
without blood.
lie fits a i uescenainy
20 cm
2.2 x W3
<20
2.4 x 103
2.6 x 10*
2.3 x 10s
spreader
2.2 x 10s
1.5x 107
7. Ox 103
2.0 x 103
<1 x 103
6. 1 x 10°
6.2
1940
65.34
i-eveis
30 cm
20
<20
20
2.3 x 107
4.7 x 107
spreader
4. 1 x 107
4.9 x 106
<1 x 103
<1 x 103
<1 x ro2
1.7 x 107
5.15
2230
64.09
usually 10 MPN/100 ml or less.
coliforms had apparently died out, but the
streptococci remained present on an
inconsistent basis. The Boone County
landfill was 6 years old when these
determinations were made.
On the other hand, the commercial
landfill had fecal indicator levels ranging
from 102 to 104 MPN/100 ml of leachate.
Possibly these levels were higher because
this was an active landfill and received
waste daily. Later it was found that the
CL-4 leachate levels decreased steadily
whereas those .from the three leachate
springs (sites CL-1, CL-2, and CL-3) had
higher levels of total coliforms, fecal
coliforms, and fecal streptococci. The
main difference was apparently that the
CL-4 leachate came from a 10-year-old
waste site by means of a pipe placed deep
within that waste. No new waste had
been placed on top of it since it was
deposited. On the other hand, CL-1, CL-2,
and CL-3 leachate samples apparently
came from the new waste deposited daily
on top of the landfill. This leachate
drained downward and emerged from
shallow surface leachate springs.
The plate counts are also listed in Table
3. One series of counts is from the Boone
County BC-1 leachate measurements,
and two are from the commercial landfill
(i.e., from the older waste and from the
newer waste described above). The
Boone County leachate microorganisms
had higher fungal and Gram-positive
bacillus counts and thus were similar to
the older commercial landfill leachate
levels. The distinguishing marks of the
newer leachate (commercial landfill) were
the low levels of Gram-positive bacilli and
fungi along with higher streptococcal
levels as determined by the KF stretococ-
cal plates. Finally, the aerobic blood agar
plates had higher counts than the
anaerobic plates, indicating that few
anaerobes were present.
The identified microorganisms from
the commercial landfill leachates include
the following:
Acinetobacter* sp.
Aspergillus niger
Cephalosporium sp.
Clostridium perfringens
Enterobactor agglomerans *
Enterobacter cloacae m
Enterobacter sp.
Fusarium sp.
Mycobacterium* sp.
Neurospora sp.
Pencillium sp.
Proteus sp.
Providencia alcalifaciens
Providencia sp.
Pseudomonas sp.
Pseudomonas fluorescens
Salmonella* sp.
Streptococcus faecalis
The bacteria significant to public health
are marked with an asterisk. They are
agents of ordinary potential hazard, such
as staphylococci, that can cause disease
when the agent penetrates the skin.
Solid Waste and Leachate
From a Landfill at Closure
A 9-year-old landfill site was examined
before closure in August 1980. The
examination at various depths of the
landfill solid wastes and the leachate
yielded unexpectedly high populations of
indicator organisms as shown in Table
11. The small numbers of streptococci
detected previously in the leachate
became significant when the solid
wastes from the landfill were examinedfl
after excavation. These results show tha^B
there were high levels of fecal indicator
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Table 11. Fecal Indicator Bacteria Levels in Solid Waste and Leachate From a 9-Year-Old Landfill at Boone County, Test Cell 1
Type of
Sample
Top soil
MSW
MSW
MSW
MSW
Leachate
MSW
Clay liner
Soil beneath
Samples Collected
at These
Descending Levels
Ft
1.5
5.0
7.0
8.5
9.0
10.0
10.5
11.0
13.0
(m)
(0.46)
(1.52)
(2. 13)
(2.60)
(2.74)
(3.01)
(3.2OJ
(3.35)
(3.96)
recai iiiaicmvr a
Total
Coliforms
2.4 x 10s
1. 1 x 10*
2.4 x 103
1.6x 105
5.4 x 10'
9.2 x 103
3.5 x 10*
5.0 x 10"
5.0 x 10"
Fecal
Coliforms
3.5 x 103
<2.0x 10"
2.0 x 10'
2.3 x 10*
3.3 x 102
3.5x10*
4.9 x 102
<2.0 x 10"
<2.0x 10"
Total
Streptococci
9.8 x 70s
2.0 x 10*
6.0 x 10*
3.3 x 10s
ND
1 1 x 10*
3.5 x 10*
2.0 x 10*
<2.0 x 10*
organisms in the top 1.5-ft (0.046 m) soil
sample. Below this, lower levels of fecal
indicators occurred at the 5-ft (1.52 m)
sample, and higher levels occurred for
the rest of the wastes extending to the
bottom of the landfill.
The levels of total coliforms, fecal
coliforms, and fecal streptococci in all
waste materials were relatively high.
Results from the solid waste were not
consistent with those from leachate
samples over the years, which showed
essentially no indicator organisms pre-
sent. The higher levels in the top soil may
have resulted from animals. Fecal
indicator bacteria survived within the
landfill, which suggests the possibility
that leachate may transport these bacteria
to the groundwater if the liner materials
were penetrated. The clay liner and the
soil beneath the plastic liner, however,
showed that few bacterial indicators
were present. These last assays demon-
strated that the microbe-containing
leachate was not able to penetrate the
clay liner and soil below to contaminate
the groundwater.
Tests for specific microorganisms in the
solid waste included Acinetobacter sp.,
Moraxella sp., Salmonella sp., and Klebsi-
ella pneumoniae all pathogens.
Summary and Conclusions
Methods were modified by applying the
bacterial stress procedures to bring about
the improved enumeration and isolation
of coliforms, streptococci, Mycobacteri-
um. Salmonella, and Clostridium species.
Newly constructed experimental lysi-
meters containing MSW, hospital waste,
and sewage sludge were studied for 3
years. Indicator organism densities and
specific bacteria found were similar for all
three types of solid waste added to the
lysimeters. Total and fecal coliforms in
the leachate decreased to <20 MPN/100
nl by the 13th week, the fecal streptococci
disappeared after 2 years. However,
several bacteria and fungi were isolated
from the leachate after 2 years.
Leachate samples were collected from
both active and inactive areas of a large
commercial landfill. Total coliforms and
fecal streptococci in the active seepage
was on the order of 104 per 100 ml, with
fewer fecal coliforms, whereas leachate
from the inactive portion generally was
free of indicator organisms. Total plate
counts were generally one or two orders
of magnitude higher for the active area
compared with the inactive area. Numer-
ous bacteria and fungi were isolated and
identified from the commercial landfill
leachate, including a number of patho-
gens.
Relatively low levels of indicator
organisms were found in experimental
lysimeter leachates that had been studied
for a number of years. One 9-year-old site
was examined closely at closure. Positive
values were found at various depths for
total coliforms, fecal coliforms, and fecal
streptococci. This result shows that low
levels of microbes in leachates do not
always mean that these organisms are
absent within the solid waste.
The full report was submitted in
fulfillment of Grant R804733 under the
sponsorship of the U.S. Environmental
Protection Agency.
Jean A. Donnelly and Pasquale V. Scarpino are with the University of Cincinnati,
Cincinnati, OH 45221.
Naomi P. Barkley is the EPA Project Officer (see below).
The complete report, entitled "Isolation, Characterization, and Identification of
Microorganisms from Laboratory and Full-Scale Landfills," {Order No. PB 84-
212 737; Cost: $35.50, 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
*USGPO: 1984-759-102-10669
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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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