R N K ENVIRONMENTAL INC. P.O. BOX 17325 COVINGTON, KENTUCKY 41017 PHONE: (606) 344-0966 .- . I July 26, 1994 Chemical Specialties Manufacturers Association Attn: Doug Frat2 1913 Eye Street, N.W. Washington, DC 20006 Director of Scientific Affairs Dear Doug : Enclosed, you will find a copy of our draft Research Paper that we have submitted to the Water Environment Research Journal titled IIImpact of POTW Sludge on Municipal Sanitary Labdfills.lI analyses and conclusions from our study on Household Hazardous Waste (HHW) as well as data from the original EPA sludge codisposal project. satisfy EPA requirements as well as CSMA's. questions regarding this paper, please let us know. forward to your reply. This paper includes summary data and We included both as one to If you have any We look I Respectfully, - 1 ( o~::&{J.2zh I , - David L. Nutini General Manager
Transcript
R N K ENVIRONMENTAL INC. P.O. BOX 17325
COVINGTON, KENTUCKY 41017 PHONE: (606) 344-0966
. - . I
July 26, 1994
Chemical Specialties Manufacturers Association Attn: Doug Frat2
1913 Eye Street, N.W. Washington, DC 20006
Director of Scientific Affairs
Dear Doug :
Enclosed, you will find a copy of our draft Research Paper that we have submitted to the Water Environment Research Journal titled IIImpact of POTW Sludge on Municipal Sanitary Labdfills.lI analyses and conclusions from our study on Household Hazardous Waste (HHW) as well as data from the original EPA sludge codisposal project. satisfy EPA requirements as well as CSMA's. questions regarding this paper, please let us know. forward to your reply.
This paper includes summary data and
We included both as one to If you have any
We look
I Respectfully, - 1 ( o~::&{J.2zh I , -
David L. Nutini General Manager
Impact of POTW Sludge on Municipal Sanitary Landfills
Riley Kinmane, Dave Nutini*l, David Carson*2, Joseph Farrel*3, and Janet Rickabaugh*
,
An experimental sludge-MSW sanitary landfill program was set up in
June 1982 to evaluate the impacts of sludge co-disposal on air quality,
surface water quality and ground water quality.
included co-disposal, refuse only and sludge-only landfills.
physical, chemical and biological parameters have been'measured to
document leachate and gas quantity and quality.
various measurements on sludge and MSW, certain landfills were spiked
with-a priority pollutant-solution to investigate the impact that.- hazardous type chemicals might have on leachate and gas quality. The
study was deconimissioned in August 19922, some 10 years plus 2 months
after initial loading.
Disposal options
Various
In addition to the
A large quantity of data have been generated on this study. This
paper contains the results in summary fashion of the 10 year evaluation
of 28 sludge-MSW co-disposal landfills.
the sludge-MSW co-disposal is a good marriage.
Basic findings indicate that
.Riley Kinman*, University of Cincinnati, Dave Nutini*l, RNK
Environmental, Inc., David Carson*2, USEPA, Joesph Farrel*3, USEPA, and
Janet Rickabaugh*, University of Cincinnati
1
Both entities enhanced the behavior of the other.
H W compounds, did not impact the quality of leachate or gas.
analysis indicated the sanitary landfill is very protective of the
public health and the ambient environment.
Priority pollutants,
GC/Ms
sludge concentrations of 10, 20 and 30% by weight caused gas
production (biological decomposition) to start faster than the
controls.
months for the control (MSW only).
degraded to lower levels than the sludge disposed in 100% sludge
landfills. Sludge-MSW leachate was of better quality than the MSW or
sludge-only controls.,
this paper.
A burnable gas ( 5 0 % CH4) was attained in one month versus 12
Sludge co-disposed with the MSW was
These findings and others will be discussed in
Key Words:
Pollutant, Coliforms, Anaerobic, Heavy Metals.
Introduction
Sludge, Co-Disposal, Municipal Solid Waste, Priority
In June, 1982, 28 experimental sanitary landfills were constructed
to evaluate sludge and MSW co-disposal at the USEPA Test and Evaluation
Facility in Cincinnati, OH. This report covers the closure of these
landfills and the final evaluation of their contents.
project consisted of 20 large-scale (1.8m. diameter by 2.7m long) 6ft
The original
diameter by 9 ft tall simulated landfills with various mixtures of co-
disposed sludge and municipal solid waste and municipal solid waste
only. See Table I for the loadings. There were also eight sludge-only
landfills, cells, which were smaller in size.
the large landfill and small landfill details respectively.
See Figures I and I1 for
All
landfills were filled in June 1982 with MSW from Cincinnati, OH,
105,000 pounds and sludge from the Washington, D.C. Blue Plains POTW,
5
".
Table 1. Original Program Design
Sludge Priority Waste Test sludge Loading Pollutant Infiltration Height cell me ( % I Spike Rate
Low Low High High
1 2 3 4
' 5 6 7 8
9 10 11 12
AD LT AD LT
AD LT AD LT
P 9 LT AD LT
1.8 1.8 1.8 1.8
1.8 1.8 1.8 1.8
1.8 1.8 1.8 1.8
1.8 1.8 1.8 1.8
1.8 1.8 .
1.8 1.8
0.6 0.6 1.8 1.8
0.6 0.6 1.8 1.8
.Lu 10 10 10
20 20 20 20
I
Low Low High High
30 30 30 30
Low Low High High
13 AD 14 LT
. 15 AD 16 LT
20 20 '2 0 20
Spiked Spiked Spiked Spiked
Low Low High High
0. 0 0 0
-- Low High. _ _ Low High .
. . .. ...
Sludae-Onlv.: 21 AD 100
100 100 100
Low Low Low Low
22 LT
24 LT 23 AD
25 AD 100 100 100 100
Spiked Spiked spiked Spiked
Low Low Low Low
26 27 28
~
LT A D . LT
FJ) = Anaerobically Digested Sludge (16 percent s o l i d s ) LT = Lime Treated Sludge (16 percent solids) 10, 20, etc. = Percent ( % ) sludge addition by wet weight of
sludge/refuse mixture spiked = Received solvent-based spike containing twelve
priority pollutants Low = Received an annual water infiltration rate of 0.500
liters per kilogram of cell waste (refuse and/or sludge) on a dry weight basis
High = Received an annual water infiltration r a t e of 1.000 liters per kilogrm of cell waste (refuse and/or sludge) on a dry weight basis
3
c
.c 0.91m ;I
INFILTRATION LINE+ c
! ! i I
1 I
I
j 1 I
-
- . . . .- ' . . . .. . . . . ' . -. . .. .-
0 .i V q- 0
i_
- 8 . ..
Figure 1. Cross section of Co-Disposal cell- 4
. ..
1
< . . - . ... . . .. .
1- JNFILTRATION LINE /
I GAS 1 PROBE
I
c
I
. INFILTRATION LINE
1 1 - i
F i g u r e . 2 . Cross section of sludge-only cells.
5
i
55,000 pounds.
efter 10 years of monitoring.
These landfills were excavated in August-September 1992
Approach and Objectives
To simulate sludge landfilling as it is commonly practiced, the program design included laboratory-scale steel tanks (or cells) filled
with municipal refuse and various loading rates of municipal wastewater
sludges.
section from a landfill), operated under anaerobic conditions and
according to the initial experimental variables.
was added on a monthly basis to reflect expected rainfall conditions.
Leachate was drained monthly and samples were collected and analyzed
for standard chemical constituents es well as the presence of trace
organic compounds.
samples collected for subsequent analysis.
readings were routinely recorded to monitor changes due to
decomposition processes or seasonal fluctuations.
program design, the simulated landfills can be evaluated singularly or
compared to one another under experimental conditions corresponding to
actual field conditions.
Conceptually, each cell acts as an independent landfill (or
For each cell, water
Additionelly, gas was quantified and periodic
Lestly, temperature ._
Under this general
The specific program design outlined in Table 1 details the waste
loading conditions for the sludge-only, refuse-only, and co-disposal
(sludge and refuse) cells.
various sludge/refuse ratios.
percent sludge ( i o 0 percent refuse), and 10 percent, 20 percent, 3 0
percent, and 100 percent sludge loading rates.
variables included the use of two different sludge types, two
infiltration rates, different cell heights and diameters, and the
A total of 28 cells were filled with
As shown, these retios included o
Other experimental
6
spiking of eight cells with a priority pollutant stock solution. AS
previously mentioned, the project test cells were located at the U.S.
EPA Test and Evaluation Facility in Cincinnati, Ohio. The co-disposal
cells (NOS. 1 through 2 0 ) were placed in a stacked arrangement of two
lower rows of five and two upper rows of five. Reinforced concrete
footers support the lower cells while the cells are supported on
a steel framework. The sludge-only cells (Nos. 21 through 2 8 ) are
shown as small diameter tanks, located in front of the co-disposal
cells at the floor level.
The primary objective of this program was to monitor and evaluate
leachate and gas release from sludge landfills, constructed and/or
operated under the following conditions:
1.
2. - .
3 .
4.
5 .
6.
Sludge landfills receiving anaerobically digested sludge versus those receiving lime treated sludge.
Sludge-only landfills versus refuse-only landfills versus co-disposal landfills.
Co-disposal landfills receiving various sludge loadings (10 percent, 2 0 percent, and 30 percent of the total sludge/refuse mass).
Landfills receiving low versus high infiltration rates.
Shallow versus deep landfills.
Landfills spiked with elevated levels of specific organic compounds, versus control landfills.
Background
A large quantity of municipal POTW sludge is disposed i n sanitary
landfills. Perhaps as much as 85% of the sludge produced in wastewater
treatment is thickened and pretreated by either anaerobic digestion or
aerobic digestion and then is co-disposed with MSW in Subtitle
sanitary landfills.
I'D"
Some sludge is thermally treated by wet air
7
,
oxidation and some amounts (10%) are incinerated. Ash and residues
from these treatment processes ere also placed in the sanitary landfill
for final disposal.
of sludge-MSW co-disposal operations.
This project was conceived to evaluate the impacts
8
Landfill Design and Construction
The laboratory-scale test cells were designed and constructed
prior to the June 1982 loading activities.
was to provide a durable, gas-tight container of sufficient scale to
promote the decomposition processes which occur in an actual refuse,
sludge,. or co-disposal landfill. The cells were rolled steel tanks,
double-welded at the seams, with two interior coatings of rust-proof,
high-build epoxy sealer. The co-disposal and refuse-only cells (Nos. 1
The purpose of the design
through 20) were 1.8 m (6ft) in diameter and 2.7 m (9ft) in height.
Due to the heterogeneous nature of municipal refuse, a greater waste
volume was selected for the co-disposal cells. The smaller sludge-only
cells (Nos. 21 through 2 8 ) were 0.6 m (2ft) in diameter; four were 2.7
m (gft) tall, and the remaining four were 1.5 m ( 5 f t ) tall. A typical
test cell cross section for the co-disposal and sludge-only cells is
provided in Figures 1 and 2.
Further features of the test cell design include infiltration
lines, leachate drains, openings for the temperature and gas probes,
and 20 cm (8 in.) structural beams welded to the cell bases. The
infiltration lines consist of 2.5 cm (1 in.) diameter threaded steel
pipe, protruding into the head space of each c e l l . Not shown on the
infiltration l i n e s are interior, full-spray brass nozzles for
proportioning the monthly infiltrations over the entire waste surface
area. The leachate drains are 5.1 cm ( 2 in.) diameter, threaded steel
nipples with PVC piping and valves for leachate collection.
for the temperature and gas probes received 0.6 cm ( 0 . 2 5 in.) brass
bulkhead fittings and were sealed with silicon-based compounds.
structural steel supporting beams were used to span the concrete
o?enings
The
9
footers and the steel framework at the time of cell loading and
placement. The completed test cells were delivered to the EPA T & E
Facility by March, 1982.
of the loading activities in June 1982.
They remained at floor level until completion
Required quantities of municipal refuse were obtained from City of
Cincinnati collection vehicles and delivered to a specially prepared
receiving area outside the T & E Facility.
obtain a waste medium which typified household refuse generated in the
The purpose here was to
U . S . A quantity of over 45 metric tonnes ( 5 0 tons) of municipal refuse
was delivered to the project site where it was manually mixed.
manual mix consisted of breaking open all plastic bags, spreading
materials, and removing non-representative refuse materials such as.
pianos, tires, and commercial items. After the mix was completed and
prior to cell loading, a representative three percent sample was
segregated from the waste mass and a refuse characterization was
performed. The refuse was manually separated and weighed to determine
the physical composition. The 14 sorting categories are shown in Table
3 .
This
In order to further assess the physical and chemical inputs to the
cells from the refuse quantities, refuse grab samples were obtained for
chemical composition and moisture content analyses. Results from this
sampling and analytical effort are presented in Table 2 . Moisture
content for the unshredded, as-delivered refuse averaged 4 2 . 2 percent,
based on 12 samples. The refuse was finely ground prior to
determination of the other listed parameters.
10
1N 1 -
0,
1 - I C
N
aJ 1 A %I E
11
f
Table 3 . Refuse Physical Composition
Component Percent(%) Wet Weight
Paper Textiles Garden Waste Plastic Ferrous Metal Telephone Books Wood Glass Food Waste , Diapers Non-Ferrous Metal Ash-Rock-Dirt Rubber-Leather Fines*
Various operation and monitoring activities were performed on a
continuous basis for this long term experiment. Specifically, test
cell temperatures (one probe per
basis for the first two months.
test cell) were recorded on a daily
Thereafter, temperatures were
I
monitored bi-weekly o r on an as-appropriate basis.
leachate was drained from every cell each month.
In addition,
The volume of
18
leachate drained was recorded to aid in the compilation of a moisture
balance summary. Two representative samples were then collected from
the leachate drained each month for each cell.
prepared for standard chemical analysis and transmitted to the
University of Cincinnati.
quantitation of trace organics by EPA analytical personnel.
The first sample was
The second sample was collected for GC/MS
Infiltration water was applied to every cell each month
immediately after the leachate had been drained as described above.
Table 5 shows the infiltration schedule for each test cell.
added was based on an annual rate applied against the total quantity
(dry weight) of wastes present in each cell.
low infiltration rate (similar to Midwest U.S. percolation estimates)
or the high infiltration rate (twice the low rate).
maintenance activities were also employed each month f o r general
housekeeping purposes and to ensure air and water tightness of all
cells.
?he volume
Cells receive either the
Inspection and
Monitoring activities center on providing physical/chemical
descriptions of the in-place wastes, infiltration water, product gases,
end generated leachates. on an ongoing monthly schedule as indicated in Table 7 . Standard
chemical analyses performed on leachate samples in the laboratory
included pH, alkalinity, volatile acids, total and volatile solids,
total organic carbon (?OC), chemical oxygen demand (COD), total
Kj'eldahl nitrogen (TKN), total phosphate, chlorides, sulfide, seven
metals, and trace priority pollutants.
analyses, gases generated from the cells were sampled each month and
Generally, monitoring parameters were tested
In conjunction with the above
19
.Table 7 . A n a l y t i c a l Schedule
I I\." I "
Incoming Wastes I n 4 1 ace Inf 11 trat ion Gas Leachate Frequency Measurement Refuse S1 udges Wastes Water
!as te Character i za t ion loisture Content 'empera ture '01 une 'roduc t i on Ra te luality+ . f l lkalinity cidi ty ola ti le Acids otal Soljds (TS) olatile Solids ( V S ) otal Organic Carbon (TOC) hemical Oxygen Demand (COD) otal Kjeldahl Nitrogen (TKN) otal Phosphorus h l or ides ulfide ( S = ) admium (Cd) hrmium (Cr)
Daily on in-place wastes for first 1 to 3 months (or until temperatures stabilized); monthly thereafter. Honthly on infiltration water and leachate (when generated).
GC analysis for methane, carbon dioxide, nitrogen, and oxygen. Initial prlorfty pollutant scan by GC/HS on in-coming sludges. Thereafter, quarterly quantities of nine
target priority pollutants present in the test cell leachates. - .
Table 8 . Comparison of Waste Compositional Categories in 1982 versus 1992.
Cateaory
Paper
Textiles 11.9 5.0 10.5 2.6 Garden
Plastic 8.1 8.8 6.3 5.5 Ferrous Metal
Telephone Books 4.6 7.7 Wood
Glass
Food
3.2
2 . 8
1.6
Diapers 1.5 - .
Non-Ferrous 1.5
Ash-Rock-Dirt 1.4
Rubber-Leather 1.1
Household Hazardous Waste ---
1.6
3.8
0.5
0.7
* 2.0
0.6
2.2
0.3
0.2
Fines* 0.1 9.6
Sludge --- 0.3
Roofing ---
*Fines = material passing through a 2 5 m (lin.) sieve a Total Sample Weight = 2594 lbs b Total Sample Weight = 1714 lbs
. ” _.
2 1
h) h)
9 10 11 12
13 14 IS 16
17
19 20
18
21 22 23 24
25 26 27 28
LIAD 10 LILT 10 HIAD 10 IiILT 10
LIAD 20 LILT 20 1nAD 20 IIILT 20
1.1 AD 30 LILT 30 KIAD 30 tri LT 30
LIAD 20SP LILT 2OSP tnm 20SP €II LT 20 SP
LI 0 HI 0 LI 0 til 0
LI AD SI1 LI LT SH LI AD n LI LT TL
LI AD SII SP Ll LT SH SP LI AD TL SP LI LT TL SP
24 24 24 24
24 24 24 24
24 24 24 24
24 24 24 24
24 24 24 24
24 24 24 24
24 24 24 24
1 1 16.7 1 1 16.0 1 1 16.7 I 116.4
1264.4 1263.3 1264.3 1263.6
14Go.9 1459.3 1460.6 1459.3
1264.3 1263.3 1201.5 1264.3
902.7
902.9 902.8
151.1 150.6 452.2 451.3
150.8 150.7 452.2 45 1.3
902.8
1300.9 1300.8 260 I .a 260 1.7
1231.7 1231.7 2461.4 246 I .4
1 194.3 1194.3 2388.6 2388.6 '
1230.7 1230.7 2453.0 2153.0
1237.2 2474.7 1237.2 2414.7
26.6
84.3 84.2
29.0
84.7 84.4
28.8
28.9
450 501
1657 1655
536 58 1
1721 1780
687 172
1535 1853
582 517
I727
368 1578 SI8
1432
61 81 87
1 87
68 85
134 21 1
1650. . -
1859.80 1808.76 1847.3@ 1850.15
1858.35 1813.25 1806.35 1761.45
18G9.5 1 1782.35
1812.15
1810.65 1875.38 1872.05 1787.50
1668.80 1593.55 15 19.35 164 1.20
1 18.02 101.02 396.62 350.27
4 16.08 96.33
402.19 3 15.95
21 18.85
1.44 1.40 1.43 1.44
1.52
1.48 1.44
1.57 1 .so 1.52
1.48 1.53 1.53 1.46
1.35 1.29 1:23 1.33
4.26 - . .
4.78 4.17
15.02
1.48
1-78
3,60
3.43 4.85 3.76
60.92 62.2 60.30 75.5 62.47 65.8 62.49 62.0
62.10 64.9 6 1.54 75.7 63.10 73.2 62.62 75.3
62.88 72.6 61.81 69.9 66.9 1 70.5 63.77 72.6
61.54 70.8 62.29 77.8 63.87 73.3 63.01 73.0
59.57 68.3 60.58 54.4 57.50 69.5 61.15 13.8
80.92 73.9 67.14 66. I 82.70 70.3 80.72 81.0
93.72 74.0 76.83 69.0
80.52 71.1 82.59 80.8
LI = Low Infiltration III pliigh lnfiltratibn
17. = Tnll Test Cells SI 1 = Shoit Test Cells
AD = hncrobiccrlly Digested Sltdgc SP - PnWity Pollutant Spike 10, eta. = P m t (%) Sludge Addition LT = Lime Trtstcd Sludge
analyzed by gas chromatography for methane, carbon dioxide, nitrogen,
and oxygen contents.
Results and Discussion
Gas Quantity and Quality
The production of methane from anaerobic decomposition could serve
as an important fuel supplement in the near future.
the production of methane in six month increments for all 2 8 test
cells. More important is the relationship between methane
concentration and the state of decomposition in a given cell.
relationship between methane production and rate of decomposition is
important to the evaluation of sludge landfilling.
data used in conjunction with gas quality information provides a
complete picture of the decomposition of carbon based wastes.
Table 10 presents
The
Leachate quality I
Daily operations of this project included holding the cells under As a result generated gases, the products tight anaerobic conditions.
of anaerobic decomposition of organic materials, were detected
immediately following the loading operation in June 1982.
first year of operation, all 28 cells required venting of product gases
on a periodic basis, usually every two or three days.
second year, an automatic venting system was installed.
During the
Early in the
The system
maintained the cells under a constant anaerobic condition, but freed
the operator for the performance of other duties.
taken during either venting procedure, and gases were vented directly
to the atmosphere outside the T&E Facility.
No measurements were
, . .-
In an effort to document test cell gas production and to
investigate the effects of sludge/refuse loading ratios on gas
quantities, 24-hour sampling surveys were conducted bi-monthly during 2 3
Table - 10 . Percent Methane At Selected Intervals
Test Time ( Months) Cell Description 6 12 18 24 30 36 4 0 47
1 2 3 4
5 6 7
- 8
9 10 11 12
13 14 15 16
17
19 20
. i a
21 22 23 24
25 26 27 28
LI AD 10 LI LT 10 HI AD 10 HI LT 10
LI AD 20 LI LT 20 HI AD 20 HI LT 20
LI AD 30 LI LT 30 '
HI AD 30 HI LT 30
LI AD 20 SP LI LT 20 SP HI AD 20 SP HI LT 20 SP
LI 0 HI 0 LI 0 HI 0
LI AD SH
LI AD TL LI LT TL
Lr LT SH
LI AD SH SP LI LT SH.SP LI AD TL SP LI LT TL SP
47 36 50 36
51 32 52 49
53 28 52 54
31 '
50 .
42 54
13 14
6
58 2
63 1
59 1
57 75
a
53 54 53 56
56 47 56 53
55 48 61 55
56 55 49 55
47 29 32 32
58 7
58 6
59 7
62 57
54 53 54 53
55. 54 56 52
54 56 56 55
55 53 46 54
51 45 47 41
51 22 59 48
50 42 59 76
54 52 54 52
54 54 55 54
54 53 56 55
56 53 53 55
53 40 51 44
48 3
60 38
44 28 52 69
53 55 51 55
54 52 57 55
53 54 57 58
55 53 56 54
52 51 52 50
52 22 50 36
49 23 53 50
52 57 59 59
58 59 59 57
55 56 60 56
53 57 59 58
56 56 54 '5 2
68 64 58 35
50 32 56 52
59 58 59 58
58 58 59 57
59 56 60 57
59 58 57 59
56 55 55 54
49 66 67 52
53 46 57 58
58 56 -- -- 60 63 60 60
-- 40 49 60
58 41 61 43
54 55 52 57
47 -- -- 48
37 -- -- 44
LI = Low Infiltration TL = Tall Test Cells HI = High Infiltration SH = Short Test Cells AD = Anaerobically Digested Sludge SP = Priority Pollutant Spike LT = Lime Treated Sludge 10, etc. = Percent ( % ) sludge
Addition .. I
24
. f *
6
5 -
I h
MLTHANL
I 1 0 LO 20 30 4 0 50
HONTKS ?lpura 4. Biogaa Compoaitlon XSW + SS + S p l k e ,
Avg Numbar 15 L Number 16 ..- -
CARBON DIOXIDE
HETHANE
HONTHS
rigure S. Biovaa ~omvoaition XSW only, A V ~ . Nuber I8 L Number 19
10 15 20 25 0 5
HONTKS
Figur. 6. Benzane Flux
4 - 2 7 Hsn + ss
3 - +a usw + ss +*la HSW ONLY
USW ONLY 2 ’
1 -
0 - ,
10 15 20 25 0 5
25
HONTHS
the first 24-month monitoring period.
operation, a 72-hour sampling survey was both the 24-hour and the 72-
hour sampling surveys.
auantify - the raw amount of gas generated over an approximate 24-hour
period. On the gas sampling day, each cell was vented down to an
arbitrary low positive pressure, and the valves were then closed.
Twenty-four hours later, gases were vented into Tedlar plastic bags and
pumped through a wet test meter until the test cell again reached the pre-established low positive pressure. Subsequent results for this gas
measurement procedure yielded values for gas production in liter/day or
liters/hour at standard temperature and pressure (STP).
During the third year of
The 24-hour gas production surveys attempted to
. Table 11 summarizes the gas production measurements performed on
20 occasions during the 48-month monitoring period for all 28 cells.
Gas generation rates are indicated by liters of gas (at STP) per hour
and serve as rough estimates for daily gas volumes.
subject to inaccuracies due to partial dependency on operator
discretion during measurement, daily fluctuations in gas generation,
and ambient variations in barometric pressure and temperatu, ye within the T&E Facility.
presented for September 1983. These data were collected by
continuously monitoring gas production over a 17-day period. The goals
were (1) to eliminate operator-dependent biases in gas measurement, and
(2) to evaluate the accuracy of extrapolation from a single 24-hour
- - The data shown is
Special attention should be assigned to the data
varied significantly according to sampling
could be established according to cell
codisposal cells, production rates were 26
measurement.
While generation rates
month, slight relationships
loading variables. For the
. I -
T A B L E l l . SUMMARY OF GAS PRODUCTION MEASUREMENTS FOR F I R S T 4 Y E A R S
1 l I M X ) 4. ai 2 11 I1 lo * 1.s I w m w ) i 6.12
2.a i H I L I M
0 4.: 0
5.54 4.a
12.16 4.38
5.11 1.01 4.11
2.24
s.%
1.68 1 .6 1.2.)
io. n
3.83
a 13
am a 11 am a 74 a o i
am a 01 as acp
La K)l
1160 l . u
11.x) 199
7. m 14.m a. 43
4. n
ax 22. al 9. a
6% al 5.33 9.18 29. io 11.9
2. a 6% a47 am a i s
a 7s am a 13
a 9 a 13
a@
0. O2
7.19
124
9.93 4.u
16.43 5.x a 31
14.03 19. al 7. b3
15. 10 1.a
11. P 2l .P
4 . s 5.93
15. to 17.m
3.0) 1.11 1.23 a 01
a i 4 aa as aw a 07 am a 14 a8 6.65
uu
1i.m 6.14
la. m 11.70
)S.Ol
Uu)
14. K)
12.70 l a IO
7.47 11.m 15. K) 15. ’k)
3.63
9. n 1i.a
a m
a41 aa at) a 11 am a s am am a 01
a zi a 37
1.11
94
~2 .10 IZ.M n.co i i m i r c o 6.51 7.64 182 14s 4 . 7 8 k.0~ us la 1 7 0 2 . 9 2.x ari 11
The third year of monitoring gas production showed definite
changes in the decomsosition processes occurring in the various cells.
The refuse-only test cells (Nos. 17, 18, 19, and 2 0 ) displayed a
significant increase in gas production rates during this time. In June 1985, Test C e l l 17 reached a peak gas production rate of 12.84 liters .
per hour.
over time.
cells which also were measured and confirmed by most of the leachate
quality variables.
In general, the codisposal gas production rate decreased
This indicates a decline in anaerobic activity in these
1.
2 .
3 .
4 .
A summary of gas quantity data revealed the following:
Gas production was significantly influenced by sludge addition.
Gas production was not dependent upon the sludge loading ratios this experiment nor upon the sludge type in codisposal cells
Refuse-only cells lagged behind codisposal cel1s.i.n gas production by nearly two years.
Sludge type did significantly influence gas production in sludge only cells. ..
of
2 8
5. 3.s in the cese of gas conposition, gas production did confirm earlier observations made concerning rate of decomposition, thus providing en indirect meens of monitoring decomposition in a given cell.
In addition to the standard leachate chemical analyses, leachate
samples were collected from the cells and analyzed by gas
chromatography/mas spectrometry (GC/MS) for nine target priority
pollutant compounds. These data are presented in Table 6. Leachate
analysis were not performed for benzene, toluene, and ethylbenzene,
though these compounds were included in the original 12 compound spike.
They were excluded because purge 2nd trap tgchniques required for
proper,sample preparation would have approximately doubled the cost of
the analytical program and sufficient funds were not available. These
compounds were analyzed in the of f gas from the spiked cells end
controls for VOC analysis.
A review of the experimental data has shown several important
trends in priority pollutant leaching.
by discussing specific compounds such as acenaphthene, dibutyl
phthalate, naphthalene, and pyrene.
A c en e D h t h en e
These trends are best presented
Yearly average values for each of the four monitoring years and
for both codisposal and sludge-only cells are presented in Table 12.
These data show that both spiked and control cells exhibited similar
concentrations of acenaphthene in their leachate during all four
monitoring years.
peak values during the second year of monitoring.
The data also shows that acenaphthene levels reached
*7 This trend Fs
illustrated in Figure 8. Figure 8 compares average concentrations of 29
Table - 12. Average Concentrations of Acenaphthene for four Years
Year Year Year Year 1 2 3 4
158.0 110.0
175.0 188.0
118.1 84.2
47.9 67.1
sludge-Only Control (pg/L) Spiked ( )Ig/L
107.0 84.2
252.1 122.3
105.0 101.1
73.5 87.5
30
acenaphthene for a representative set of spiked codisposal cell end its
corresponding control cell. In Year 1, both cells averaged between 150
to 160 ug/L irtheir resulting leachate.
levels had increased to over 200 Ug/L.
decreasing acenaphthene concentrations, though the control cell did not
decline as much as the spiked cell.
decline in acenaphthene throughout Year1 4 .
By Year 2 , acenaphthene
In Year 3 , both cells showed
Both cells continued to show a
In addition to examining trends in acenaphthene concentration, the
variability of the data was checked.
evaluated by using the coefficient of variation (CV). This statistical
meesure is useful as it allqws a comparison of different sample groups,
each with different arithmetic means.
control cells showed that spiked cells eyhibited a lower degree of
variability than corresponding controls. In the codisposal group,
spiked cells often had a CV of less than 20 percent, while the control
cells ranged from 0 to 99 percent.
showed similar coefficients of variation for both spiked and control
cells.
The data variability was
A comparison of all spiked and
I;n examination of sludge-only cells
Di bu tvl P h t h a 1 ~t e
Average concentration data and leaching trends for dibutyl
phthalate are presented in Figure 9.
phthalate for both codisposal end sludge-only cells are shown in
Figure 9 for the first four years of monitoring.
monitoring for this compound caused the suspension of analysis after
the third year.
Mean concentrations of dibutyl
The high cost of
A comparison of both codisposal and sluage-only cells did not show
a large difference in dibutyl phthalate levels for spiked and control 31
I 6 3
1 . 5
" 5 f B E a
codLpD.oI COU 190. lbo 170 1CO 160 140 Is0
110 100 90 bo 70 60 SO 40 30
10
iao
ao
Figure . 8 .. Leaching trends o f rcenaphthene.
Y w 1 Y M r 2 Yoor 3 Yoor 4
T I C a w C d b (59 SPi*.dC4L.
TC 15. P. I;. a x u. E Y. u
Figure 9 . . Leuhing trandr o f dibutyl phthalrta .
-i
cells.
monitoring the sludge-only cells. During this time, spiked sludge-only
cells averaged over twice the levels of dibutyl phthalate found in the
control cells.
phthalate was different x+xn that of ancenaphthene.
graph illustrating average concentrations for representative sets of
The only exception to this rule was found in the third year of
Figure 9 shows that the leaching trend for dibutyl
Figure 9 is a
sludge-only cells. During the'first two years, relatively small levels
of dibutyl phthalate were found in the leachates from both cells.
However, in Year 3 , dibutyl phthalate concentrations for each cell
increased by more than a factor of 15.
A review of dibutyl phthalate data showed a high degree of
variability for codisposal and sludge-only cells. The coefficient of
variation for annual data (excluding zero values which indicated only
one measurement) ranged as follows:
Control Spiked (Percent) ( Percent )
codisposal 8 to 141 26 to 9 3
Sludge-only 5 to 140 2 4 to i i a Naphthalene
Table 13 shows average naphthalene data presented for both
codisposal and sludge-only cells.
that mean levels of naphthalene did not vary between spiked and control
cel ls . Similar t o acenaphthane, naphthalene concentrations in the
leachate reached peak levels during the second year of monitoring.
This trend is graphically presented for a representative set of
codisposal cells in Figure 10.
concentrations for the two cell types averaged around 300 ug/L.
A review of this table demonstrates
In the first year, average
In 33
TABLE 1.3. AVERAGE CONCENTRATIONS OF NAPHTHALENE FOR FOUR YEARS
Year Year . Year Year 1 2 . 3 4
Codisposal Control
. Spiked
S 1 udge-Only Control Spiked
351.3 279.5
666.8 514.5
356.8 424.3
647.0 795.3
208.0 189.5
51 6.5 438.3
206.6 235.0
802.5 562.4
34
Year 2 , the naphthalene levels slightly increased for the leachate of
both cells. During the third and fourth years, the average
concentration of naphthalene showed a declining trend to levels around
200 ug/L.
A general review of data revealed that naphthalene concentrations
showed a low degree of variability for both codisposal and sludge-only
cells. The CV values for the codisposal cell data feel between 40 and
60 percent. The CV for sludge-only data generally ranged between 30
and 5 5 percent. In the case of both cell types, then spiking of
naphthalene did not affect data variability.
Pvrene I
. Figure 11 presents yearly averages for pyrene for both codisposal
and sludge-only cells. Examining this data shows that the codisposal
control cell actually had higher levels of pyrene in the resulting
leachate than the spiked codisposal cells for all three years. . .
The
sludge-only control cells a l s o demonstrated this same phenomenon. The
graph in Figure 11 shows that leaching trends for pyrene from the
codisposal cells were different from nny of the other compounds
examined. In Year 1, levels of pyrene found in the leachate from
codisposal cells ranged up to 165 ug/L. By year 2 , these Years 3 and 4
saw pyrene levels for both the spiked and control cells fall below 25
percent of their first year level. However, Figure 12 illustrates that
this trend did not hold for the sludge-only cells. This graph
demonstrates a leaching trend similar to that exhibited by acenaphthene
and naphthalene.
Pyrene concentmtion data experienced a high degree of variability
for all cells examined. The annual coefficients of variation 35
.Figure 11.e. Lbiching trends of p y r w for codirporal ca l l s .
Y.er 1 Ioor 3 Yoor 3 Yoor 4
n- [La C r r M COY. 1c u. u. a. u
[z9 Spi-d C d b L $1. 26. 8). 1
FIgurr 1 2 . Leaching trrnds o f pyrenr for sludge-only c e l l s .
45
Ffgure 13. ,Leeehatr COD YS tlm for Test Cells 3 , 7, 11, and 18
(excluding zero va lues which ind ica ted a s i n g l e measurement) f o r t h e
var ious c e l l s ranged as follows: Control Spiked
(Percent ) (Percent)
Codisposal 11 t o 1 4 1 4 t o 1 4 1 1 t o 200
Sludge-Only 7 t o 1 7 3
Percent Recovery I
During t h e e a r l y s t a g e s of t h i s p r o j e c t , problems were encountered
i n t h e GC/MS a n a l y s i s of t h e leacha te sample.
l eacha te samples contained a high degree of s o l i d s ( t o t a l and
d i s so lved) due t o t h e wash-out of s o l i d s from t h e s ludge and s o l i d
Occasionally t h e
waste p re sen t i n each ce l l . The presence of these s o l i d s c rea ted a
very complex matrix f o r a n a l y s i s . Percent recovery i s a means of
checking t h e v a l i d i t y and completeness of each a n a l y s i s .
-The s o l i d s i n t h e l eacha te of ten caused percent recovery values t o
drop below 4 0 pe rcen t . Under normal condi t ions , t h i s percent recovery
would be considered unacceptable. I n o rde r t o a s s u r e t h e v a l i d i t y of
t h e d a t a , a technique c a l l e d G e l Permeation Chromatography (GPC) was
used ( a f t e r June 1 9 8 4 ) . GPc i s a technique whereby a l a r g e por t ion of
t h e higher molecular weight compounds which i n t e r f e r e a re removed
avoiding t h e l o s s of any of t h e compounds of i n t e r e s t . Table 14 shows
t h e improvement i n percent recovery da ta by employing t h e GPC
technique. I n t h e case of t h e compound presented i n t h i s t a b l e , t h e
percent recovery was improved t o 7 0 percent o r b e t t e r .
The Following a r e t r e n d s r e l a t i v e t o leachate p r i o r i t y p o l l u t a n t s
which have been observed from t h e four yea r s of monitoring.
1. The sp ik ing of p r i o r i t y p o l l u t a n t compounds i n t o both codisposal and sludge-only ce l l s d i d no t s i g n i f i c a n t l y i n c r e a s e t h e l e v e l s of
37
Table 14. Comparison of Percent Recovery Data
Mean Percent Mean Percent
Compound Recovery
Before GPC* Recovery
After GPC+
Acenaphthene 37.1 104.4
Dichlorobenzene 32.9 * 80.0
Naphthalene 45.8 96.3
Pyrene 27 ZS 75.3
* Based on 75 analyses + Based on 20 analyses
c
these compounds in the resulting leachate.
2. The leaching trends of the priority pollutant compounds varied on a compound by compound basis end were not affected by the other experimental variables of the project.
3. The variability of the priority pollutant data was not significantly Etffected by the addition of the priority pollutant spike.
4 . The use of the Gel Permeation Chromatography (GPC) clean-up technique significantly improved the percent recovery for certain compounds.
Chemical Owaen Demand
The chemical oxygen demand ( C O D ) test is used widely to assess the
pollution strength of domestic and industrial wastes. It allows the
measurement of a waste in terms of the total quantity of oxygen
required for oxidation to carbon dioxide and water in accordance with
the following equation:
CnH,ObNc t (n t 2 / 4 - b/2 - 3/4C)02 -->
nC02 + (a/2 - 3/2c)H20 + cNH3
Under this relationship, almost all organic compounds, with few
exceptions are oxidized by the action of strong oxidizing agents under
acid conditions.
A representative summation of COD data is presented i n Figures-13,
14 and 15. Similar data configurations have been maintained as in past
subsections. Figures 13 and 14 compare the codisposal of
anaerobically-digested sludge with a refuse-only control cell.
first year of activity, all four cells acted quite independently of one
another.
three codisposal cells and no relationships existed between sludge
loading ratios and these parameters, Though the COD concentretions for
the refuse-only cells were erratic, the concentrations were higher than
In the
The release rctes and concentrations were different for all
39
fhu (Yonvu)
Flgurr 1 4 - Lrachrf. COD VI tjnw f o r f a s t tolls 4 . 8, 12, and 18.
T i - (Month)
FIgum 1 5 . . Lrachrtr COD vs t h f o r T e s t Cel l s 22 and 24.
the codisposal cells. During the second year of ope ra t ion , the refuse-
only cell remained in a high COD range.
time was 23,767 mg/L. The codisposal cells (Nos. 3 , 7 and 11)
demonstrated similar COD concentrations during Months 11 through 2 4 .
Between Months 25 and 36, COD values in the refuse-only cells fell
dramatically, while the codisposal cells continued to decline. The
The average value during this
third year means were 661 mg/L, 633 mg/L, 653 mg/L, and 8,869 mg/L,
respectively for Cells 3, 7, 11, and 18. During the fourth year, all
four cells had similar COD levels that averaged between 300 mg/L and
700 mg/L.
Figure 14 describes the COD levels for the lime treated codisposal
cells and a refuse-only control cell (NOS. 4, 8, 12, and 18). This
figure shows that there were similar trends demonstrated by both the
lime-treated and anaerobically digested codisposal cells throughout t h e
third and fourth year of operation. Generally, regardless of sludge
type or loading ratio, the codisposal cell generated a more benign
leachate in terms of COD levels than the control (refuse-only) cell.
In Figure 15, a plot comparing the two sludge types is presented.
Cells 22 and 24 (LT) showed a gradual increase in COD concentration
during most of the 36 months.
exhibited elevated COD levels.
remained at consistently low concentrations during all sampling
periods.
COD concentrations. Between Months 30 and 48, Cell 22 (AD) experienced
a sharp decline in COD concentrations. This cell finally stabilized at
a COD below 3,000 mg/L, while Cell 24 averaged COD values around 18,000
mg/L. The drop in COD levels demonstrated by Cell 2 2 may correspond t o
As might be expected, the taller cell
The anaerobically digested cells
Between Months 30 and 36, both cells experienced declines in
41
the advanced decomposition of sludge (anaerobically digested prior to
cell loading.
decomposition processes similar to that which took place,
reach final decomposition earlier than lime treated sludge,
Total Oraanic Carbon
Because anaerobically digested sludge undergoes it should
Total organic carbon (TOC) is a measure of all species present in
a sample that are carbon based organic compounds.
useful when used in conjunction with other standard measurements of
pollution such as chemical oxygen demand (COD).
present TOC data for selected codisposal and sludge-only test cells.
Cells 3, 7, and 11 as well as a control cell (No. 18) are shown i n
Figure 16. In comparison with the codisposal ce l l s , the refuse-only
cell held consistently high levels of TOC with mean concentration of
10,790 mg/L for the first two years.
refuse-only cell saw TOC concentrations drop to level equivalent to the
codisposal cells.
year, TOC values stayed at a similar level for both the codisposal and
refuse-only cells.
This parameter is
Figures 16, 17 and 18
Between Months 25 end 31, the
Throughout the remainder of the third and fourth
A plot for the lime-treated codisposal cells and control cell
(Nos. 4 , 8, 12, and 18) is shown in Figure 17.
the comparison of the anaerobically’digested codisposal cells and the refuse-only cell held f o r the data presented in this figure. As in the
review of COD data, both codisposal and refuse-only cells exhibited the
same low levels of TOC during the Third and fourth years of monitoring.
Figures 13, 14, and 15 and 16, 17 and 18 enforce the conclusion that
the codisposal cell generated a more benign leachate 18 months before
the control cell.
Trends reported during
4 2
*
. . . . -
Flgura 17. Lerchrtr TOC VI t ima for Tort t o l l s 4, 8, 12, and 18.
i a
11 t 1 10
0
8
7
I
0
4
3
a 1
0
Figure 18. Lerchrtr TdC VI tlnu f o r Test Crllr 21. 22, 23. and 24.
a 1 .D
. .
Flguro 19. L e ~ c h i t ~ TW( VI tlnu for Test Cells 3, 7, 11. and 18.
43
Figure 18 visually displays the TOC levels for both sets of
sludge-only cells. Both anaerobically digested sludge cells showed a
slight decline for the entire project.
demonstrate a distinct relationship between cell height and TOC levels.
Generally, the TOC levels of the lime treated sludge gradually
This sludge type did
increased as a function of time through Month 30. In the remainder of
the third and fourth years, Cell 2 4 stabilized, while Cell 2 2 sharply
declined and leveled off at a TOC concentration similar to Cells 21 and
23. This type of behavior was to be expected with lime treated sludge.
Lime addition stabilized the sludge by raising the pH, thus creating an
environment non-conducive to the survival of microorganisms.
result, the sludge will not create odors, putrefy, or pose a
significant health hazard as long as the elevated pH level is
maintained. Both pH and alkalinity measurements for these cells show
that lime was leached out during the experiment.
leached out, the pH within the test cells dropped significantly and the
As a
As the lime was
sludge began to reinfect and putrefy.
microbiological activity in Years 2 and 3 endorses this hypothesis.
The decline in TOC levels in Cell 2 2 may be attributed to the smaller
quantity of sludge present in the cell.
Total Kieldahl Nitroaen
The resurgence of
Total Kjeldahl nitrogen TKN) is a measure of all nitrogen present
in organic compounds including ammonia. These compounds are sometimes
called organic nitrogen and can include the following compounds: amino
acids, amines, amides, imides, and nitro dervivatives. Of these
compounds, most organic nitrogen occurs in the form of proteins,
4 4
F l g u n 20. Lorchrtr TU VI tima f o r Test Cells 21. 22. 23, and 24.
Flgure 21. Lawhate chior lb VI tims for Tes t Cel ls 3 , 7 , 11, and 18.
polypept ides , and amino a c i d s .
TKN versus time f o r c e r t a i n codisposal c e l l s and sludge-only c e l l s .
Figures 1 9 and 2 0 show t h e p l o t s f o r
TKN l e v e l s f o r t h r e e anaerobica l ly d iges t ed c e l l s and one c o n t r o l
ce l l a r e d isp layed i n F igure 1 9 .
between s ludge loading r a t i o s and t h e con t ro l c e l l .
c e l l showed inc reased l e v e l s of ni t rogen i n t h e f irst few months of t h e
t h i r d year .
mg/L t o 435 mg/L f o r bo th refuse-only and codisposa l c e l l s .
f o u r t h year of monitor ing, TKN remained s table i n t h e codisposa l c e l l .
During t h i s t i m e , t h e refuse-only ce l l continued t o d e c l i n e t o a l e v e l
of 1 0 0 mg/L i n Month 48.
anae rob ica l ly d i g e s t e d s ludge did not y i e l d any s i g n i f i c a n t changes i n .
t h e r e l e a s e of o rgan ic n i t r o g e n .
The l e v e l s of n i t r o g e n are c o n s i s t e n t
The refuse-only
However, by Month 36 TKN concent ra t ions ranged from 2 9 9
i n t h e
The s u b s t i t u t i o n of lime t r e a t e d s ludge f o r
Figure 2 0 shows t h e p l o t of four sludge-only t e s t ce l l s (Nos. 2 1
through 24).
produced e s i g n i f i c a n t d i f f e r e n c e i n TKN va lues throughout t h e f o u r
y e a r s of t h e p r o j e c t .
percent i n C e l l 2 1 .
showed no s igns of decreasing TKN values .
Chlor ide
This p l o t shows t h a t n e i t h e r s ludge t y p e nor c e l l he igh t
I n Year 4 TKN l e v e l s fell approximately 20
The remainder of t h e of t h e s ludge only c e l l s
Chlorides occur i n a l l n a t u r a l water sources and t h e i r conten t
normally i n c r e a s e s as t h e mineral content i n c r e a s e s .
presence of c h l o r i d e s i s n o t harmful t o human l i f e , c h l o r i d e
concen t r a t ions above 250 mg/L a r e considered o b j e c t i o n a b l e f o r p u b l i c
usage.
and 2 2 .
Though t h e
Leachate c h l o r i d e concent ra t ions are p resen ted i n Figures 2 1
46
Figure 21 is a plot showing the release of chloride from Cells 3 ,
7, 11, and 18. Though this plot is for the anaerobically digested
codisposal cells, it is also representative of the lime treated
codisposal cells. This graph demonstrates that the leaching of
chloride from these cells followed a linear relationship. Table 15
reveals that all the data examined fit the linear model quite well.
The values for the correlation coefficient ranged from 0.78 to 0.98
(1.0 equals a perfect fit). A scan of regression coefficient values
presents an interesting trend. Regression coefficient "b1I represents
the change in concentration (mg/L) per unit time (months) and
characterizes the rate of chloride release. Data from Table 15 shows
that as the ratio of sludge loading increases, so does the release of
chloride. This trend is demonstrated for anaerobically digested cells.
As the ratio of sludge loading increases from 10 percent to 3 0 percent,
the release rate (as measured by 81b11) effectively doubles. Though not
as dramatic, this trend holds true for the lime treated cells also.
Figure 2 2 shows the plot of chloride concentration versus time for
four sludge-only test cells. It can be concluded from this plot that
anaerobically digested sludge produced much higher levels of chloride
in the leachate than did the lime treated sludges.
the cell height (i.e., amount of sludge present) did affect the
concentrations of chlorides in the leachate.
did not follow the same linear relationship as presented in the
codisposal discussion.
For each sludge,
The leaching of chloride
The anaerobically digested sludge had a mean
value above
below 2,010
Sulfide
8,845 mg/L and the lime treated sludge had a mean value
"J
47
Table 15. Regression Analysis of Chloride Data for Selected Codisposal And Refuse-Only Cells
3 HI AD 10
4 HI LT 10
7 HI AD 20
a HI LT 20
11 HI AD 30
12 , HI LT 30
0.91
0.78
0.87
0.87
0.98
0.89
~~
2 , 151 -42.5
1,534 -30.4
2 , 807 -53.3
1,568 -31.6
4 I 159 -79.7
1,927 -38.3
HI 0 0.82 1 , 485 -30.1 18
4 8
Organic sulfur, present in t h e plant and animal waste found in
landfills, is converted to various sulfur forms which shifts in
predominance as anaerobic decomposition progresses.
conditions and pH levels below 8 , sulfates sre reduced to hydrogen
sulfide which is evolved with methane and carbon dioxide.
important function of sulfide is its ability to form insoluble metal-
suLfi.de precipitates.
more toxic and less soluble heavy metals such as copper, zinc, and
nickel.
Under anaerobic
The
Reservoirs of sulfides could precipitete the
sulfide data for Landfill #5 are presented in Figure 23 with pH
and cadmium plotted also. Difficulties with the initial analytical
method were uncovered in April 1984. During that time, quality
assurance experiments showed that sulfide results were consistently
higher that originally anticipated. Due to matrix interferences,
Method 427D of Standard Methods was then deemed inapplicable.
replacement method, the Hach semi-quantitiative sulfide method was used
for all further analyses.
1984 are thus considered inaccurate.
As a.
Sulfide data reported for dates before June
Following June 1984, it is seen
that sulfide concentrations were lower and still somewhat erratic.
Because the Hach method is a semi=quantitative method and its accuracy
was not verified for our leachate, sulfide data obtained after June
Figure 23 Sulfide and pH versus Cadmium f o r L a n d f i l l $5
50
Trace VOC’s i n Lend? jJl- Gzs
Permissible exposure level for humans or threshold limit value Spiked landfill benzene emissions (TLV) for benzene is only 1 ppm.
ranged from 1 to 8 ppm during the first year, but were less than the
TLV thereafter. Benzene emissions were Significantly different from
t h controls at the 9 5 % confidence level.
6 ppm or less and were not significantly different from the sewage
sludge controls.
toluene.
Toluene concentrations were
These levels were well below the TLV of 100 ppm for
Ethyl benzene values were less than 1 ppm during the first year,
but rose to 4 ppm in the second year.
significantly different from the controls and were well below the TLV
of 100 ppm.
These values were not
Figure 4 and 5 show the landfill gas composition for the major
constituents and Figures 6 and 7 show the benzene flux rates for the
spiked landfills and control landfills respectively.
These flux rates are in mg/M2/day. They indicate thnt substantial 2
quantities of these materials could be disposed in the refuse mass - with . no appreciable change in landfill gas quality, that is the VOC P
concentration would still be below the TLV for that compound.
Increased biogas production tended to strip higher concentration of
VOC’s from the refuse mass. So if biogas production is enhanced by
either leachate recycle or other means, provisions must be made to
handle the increased total VOC mass in the gas.
values will be higher in this case.
Gas condensate VOC
51
Metals
Monthly leachate samples were analyzed for the presence of seven
trace metals. These metals include iron, lead , chromium, nickel , copper, cadmium, and zinc. These represent a comprehensive list of
metal parameters commonly examined when evaluating water quality.
Though each of these metals present a unique water contamination
problem, several general trends were found.
An examination of the levels of all metals in the leachate from
the codisposal cells revealed an important relationship. The leaching
of metals from codisposal cells did not appear to be influenced by
sludge type. This trend held true for all seven metals and is
graphically demonstrated in Figure 2 4 . This plot is for the leaching
of lead from Cells 7 and 12. These cells are examples of two
codisposal cells which received different types of sludges at different
loading ratios. Despite these differences, the leaching trends for
lead from these two cells are similar. A review of the remaining
metals data supports this relationship. ..
A second item depicted in Figure 24 is that the highest
concentrations of metals were leached during the first two years of
monitoring. This trend was found for all metals in both codisposal
refuse only cells. However, the release of metals from sludge-only
cells seemed to remain more consistent through the four years of -L
monitoring shown.
This trend for sludge only cells is shown in Figure 25. Figure 25
is a graph depicting the relatively stable levels of chromium which
were leached from Cells 23 and 24. A probable explanation for this
and
difference in leaching history may be attributed to the physical 52
./ d
? i
..
Time (Month) .
Figure 24 Leachate lead vs time for Test Cells 7 and 12.
. .
53
difference between the two waste types. Refuse is non-uniform, while
sludge is more homogeneous in nature. This physical difference should
influence the hydraulic characteristics of a given cell. Refuse lends
itself to the creation of pockets of water, while sludge will not
support such pockets.
definitely affect the mass transport of soluble metal compounds from
the landfill.
This propensity for changes in fluid flow will
Figure 25 also introduces another trend of metal leaching. For
most sludge only cells, those cells containing lime treated sludge
released a higher concentration of metals than their anaerobically
digested conterparts.
more permanently stabilize sludge than lime fixation. .A review of
metals data shows that this relationship holds true for six of the
seven metals in the project data base.
had a lower concentration in the leachate from the lime treated cells
than the anaerobically digested cells. This is illustrated in Figure
26. This probably occurred because the low pH found in the lime
treated cells helped to form iron compounds which are almost insoluble
in water.
solubility characteristics of the other metals as profoundly.
A final trend of metal leaching concerns the refuse-only
This is because anaerobic digestion tends to
Iron was the only metal that
The low pH of the lime treated cells did not affect the
lysimeters.
higher metals concentrations during the first four year monitoring
period.
iron from Cell 4 and 18.
metals examined.
The refuse-only cells produced a leachate containing
Figure 27 demonstrates this relationship for the leaching of
This trend was found for each of the seven
54
J
I'
3
. ..
0.5
0.4 -
0.3 -
TC 23 (LI AD TL)
/TC 24 (LI LT TL)
0.2 -
Figure 25 Leachate chromium v s time f o r Test Cel ls 23 and 24.
Time (Months)
36 42' 48
i
Figure 26. Leachate iron vs t i m e for Test Cel l s 23 and 24.
55
i
,. . . , ...
2 1.9 1.8 1.7 1.6 1.5
5 1.4 > 1.3 v n En 1.2
5 5
o e '0.8 5
1.1 1
P
;: 0.9
0.7 0.6 0.5 0.4 0.5 0.2 0.1 0
Tima ( M o n t h )
Figure 2 7 Leachate i ron vs time for T e s t Cel ls '4 and 18.
56
In summary, there were four distinct trends in the leaching of
metals.
1.
2.
3.
The leaching of metals from codisposal cells was generally not influenced by sludge type. The highest concentration of metals were released from both codisposal and refuse only cells during the first two years. With the exception of iron, the leachate from lime treated sludge only cells contained a higher concentration of metals than their anaerobically digested counterparts. Refuse-only cells produced e leachate containing a higher concentration of metels (for ell metal parameters) during the four year monitoring period.
4 .
Conclusions
Sludge solids disposed in sanitary landfills is beneficial to both the MSW and Sludge disposed. Decomposition of both is enhanced in Co-disposal.
Sludge solids caused MSW stabilization to occur faster (one month) versus 12 months.
Sludge solids caused a burnable gas (50% CH4) to be produced in one month versus 12 months for the controls.
Sludge solids caused the sanitery landfill leach- =te to be of higher quality than the leachate from MSW only landfills.
MSW only cells produced a leachate containing a higher concentration of metals. treated sludge than the anaerobiczlly digested sludge.
More metals were leached from the lime
Priority pollutant compounds (household hazardous waste compounds) spiked in the landfills did n o t chenge the leachate and gas quelity.
Conclusion number 6 suggests that collectFon programs for these materials to keep them from the landfill mey not be necessery.
A total volume reduction of 25% for the combined MSW and sludge mass was attained in the 10 year period.
In the combined setting the highest sludge concentration which remained was 25% by wet weight.
10)
11)
In the 1 0 0 % anaerobically digested sludge monofills, 75% wet weight of the sludge remained efter ten years
In the 100% lime treated sludge monofills, 50% by wet weight of the sludge remained after ten years.
57
1 2 ) Readily degradable fractions of MSW were nearly gone zfter ten years. down from approximately 7.0% for Cincinnati K34. The garden wastes were 2.6%, down from 10.5% at the begining of the study.
For example the food category was at 0.5% zfter ten years,
13) sludge contributed nitrogen and phosphorus to the HSW.
Acknowledaements
The authors acknowldege the many ,entities who have been a part of
these long term studies.
to this work; USEPA, University of Cincinnati, RNK Environmental Inc.,
SCS Engineers, IT Corporation, Council for Solid Waste Solutions. We
The following have made major contributions
further acknowldege the many students and other individuals who have
made contributions to this work; too many to name, but we remember and
thank you.
References
1. Rickabaugh, J.I. and Kinman, R.N., 1993, June, Environmental
Engineering. Division, ASCE, 119, 4 (July-August 1993). - 2. Standard Methods of Analysis, APHA, AWWA, WEF, 18th Edition (1992).
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