Prepublication •Issue for EPA libraries
and State Solid Waste Management Agencies
DEMONSTRATION OF A LEACHATE
TREATMENT PLANT
This interim report (SW-91d) describes work
performed for the Federal solid waste management program
under demonstration grant no S-803926
and is reproduced as received from the grantee
Copies will be available from
the National Technical Information Service
U. S. Department of Commerce
Springfield, Virginia 22161
U.S. ENVIRONMENTAL PROTECTION AGENCY
1977
-------
This report has been reviewed by the U.S. Environmental Protection
Agency and approved for publication. Its publication does not signify
that the contents necessarily reflect the views and policies of the
U.S. Environmental Protection Agency, nor does mention of commercial
products constitute endorsement or recommendation for use by the U.S.
Government.
An environmental protection publication (SW-91d) in the solid waste
management series.
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TABLE OF CONTENTS
PAGE
Summary and Conclusions 1
I. Introduction 5
II. Overview of Leachate Treatment Options 7
j Leachate Composition 7
Leachate Treatment ^
Summary 19-
III. Leachate Treatment System 22
Design Overview 26
Design Flow 26
Design Leachate Characteristics 26
Design Concept' 28
Leachate Collection System 28
Chemical/Physical Section 28
Chemical Precipitation 28
Air Stripping of Ammonia 30
Neutralization and Nutrient Supplementation 30
Biological Treatment Section 30
IV. Materials and Methods 32
Experimental Systems 32
System 1 - Chemical/Physical Followed by 32
Biological Treatment
System 2 - Chemical/Physical Treatment 32
, System 3 " Biological Followed by Chemical/ 32
Physical Treatment
System *t - Biological Treatment 32
Process Monitoring 32
Bench-Scale Testing 3^
Statistical Tests 35
V. Results and Discussion 36
Preliminary Results 36
Raw Leachate Quality 36
Lime Dosage 36
Sulfuric Acid Do?age 39
Phosphoric Acid Dosage 39
System #1 39
Operational Comments ^2
Cost Data **3
System #2 J3
Operational Comments ^°
Cost Data ^
111
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TABLE OF CONTENTS (Cont.)
Page
Systems 3 and A 50
System 5 52
VI. Progress Evaluation 56
VII. References 62
VIII. Appendix - Leachate Treatment Plant Operation
and Maintenance Routine 64
iv
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LIST OF FIGURES
Page
Figure - 1 Reduction of COD during Aerobic Treatment 15
- 2 Changes in TDS during Aerobic Treatment ]6
- 3 Location of Leachate Treatment Plant 2k
- k Schematic of Leachate Treatment Plant 29
- 5 Influent COD Data 38
- 6 Work Schedule 59
- 7 Work Accomplished during First Year 60
- 8 Proposed Work for Second Year 61
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LIST OF TABLES
Page
Table - 1 Summary of System 1 Operating Data 4
- 2 The Strength of Raw Leachates 9
- 3 Effect of Solid Waste Disposal on Groundwater 10
Quality
- 4 Effect of Landfill Depth on Leachate Composition 11
- 5 Theoretical Removal of Heavy Metals during 18
[ Lime Precipitation
; - 6 Leachate Treatability 20
I
- 7 Precipitation Data, Trenton, New Jersey ' 23
- 8 Effluent Criteria 25
- 9 Design Leachate Characteristics 27
- 10 Routine Laboratory Analysis . 33
- 11 GROWS Landfill Leachate Characteristics 37
- 12 System 1 Performance 41
- 13 System 1 Costs 44
/
- 14 Summary of System 2 Results 46
- 15 Effects of Chemical/Physical Treatment 47
- 16 System 2 Costs 49
- 17 Phosphorus Limitation Experiments 51
- 18 System 5 Results 53
vi
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DEMONSTRATION OF A LEACHAJE TREATMENT PLANT
R.L. Steiner, Ph.D., P.E., J.E. Keerian, Ph.D.,
A.A. Fungaroli, Ph.D., P.E.
Summary and Conclusions
The results of the operation of a full-scale sanitary landfill
leachate treatment plant are reported. The plant is designed to pro-
vide a'variety of chemical/physical and biological treatment sequence
options. The chemical/physical units include lime precipitation, sedi-
mentation, air stripping, neutralization and nutrient supplementation.
These treatment processes are designed to renove heavy metals, ammonia
and organic materials, and to encourage subsequent biological treatment
by reducing the pH and adding the nutrient phosphorus. The biological
treatment process is activated sludge. The demonstration leachate treat-
ment plant is designed to provide operational flexibility in that the
flow can be directed through the various unit processes and operations
in any sequence.
The purpose of this project is to demonstrate the efficiency of a
number of treatment sequences. Specifically, five modes of operation
have been defined and are being investigated. System 1 consists of
chemical/physical treatment followed by activated sludge; System 2,
chemical/physical treatment only; System 3, biological treatment fol-
lowed by chemical/physical; System k, biological treatment only; System
5, bench-scale studies, including activated carbon adsorption treatment.
Data have been collected which can be use'd to characterize the quality
of raw leachate generated in an operating sanitary landfill. These data
show that the leachate from this sanitary landfill source is high in or-
ganic matter (average COD/liter of 11,210 mg., average 8005/1iter of
mg) and nitrogen (average NHi,+ = N/liter of 1,503 mg). The raw leachate
heavy metals concentrations are somewhat lower than expected, possibly
reflecting the relatively high pH of the leachate. (Note that all data
have been collected with non-filtered samples.)
High concentrations of ammonia in the raw leachate exceed the
plant's effluent criteria and are sufficient to inhibit the growth of
the activated sludge microorganisms. For this reason the original plant
design has been augmented with an ammonia air-stripping lagoon.
-------
System 5 studies have been conducted for a number of purposes.
Bench-scale tests have provided optimal operating data for chemical/
physical units. In particular, Systems has provided data for the
development of lime, suIfuric acid and phosphoric acid dosages.
Activated carbon adsorption has been evaluated as a treatment
method for raw leachate. For raw leachate, carbon adsorption did not
prove to be an effective treatment procedure. The inability to use car-
bon adsorption is the result of high suspended solids loading causing
increased pore plugging and the wide range of flow variability.
Systems 3 and 4, those in which raw leachate is influent to the
biological units, have received considerable operating attention. The
preliminary results indicate that the raw leachate is not directly
treatable by biological means. The operating experience shows that
an activated sludge can not be developed on raw leachate. The failure
to develop activated sludge is attributed to the nutrient imbalance
caused by a lack of phosphorus and to an Inhibition caused by toxic
levels of ammonia.
Systems 1 and 2 are those in which the raw leachate is treated
first by chemical and physical means. The results of these systems are
most promising. Lime precipitation followed by sedimentation has been
successful in removing the heavy metals and a portion of the organic
matter. Specifically, this sequence has removed about one-third of the
dissolved solids and nitrogen; one-half of the organic matter; three-
quarters cf the suspended solids; and ninety percent of the phosphates.
The sequence has been successful in removing the heavy metals including
one-third of the cadmium; one-half of the chromium and nickel; two-
thirds of the lead and mercury; three-quarters of the copper; and over
ninety percent of the iron and zinc.
An air stripping lagoon is included in the chemical/physical
treatment sequence because of the excessive ammonia levels in the raw
leachate. During the lime precipitation/clarification/air stripping
mode of operation, the following removal efficiencies have been achieved:
56-57 percent BOD and COD; approximately 60 percent of the ammonia-N and
total Kjeldahl-N; approximately 67 percent of the suspended solids; 50-
65 percent of cadmium, nickel and mercury; 70-80 percent of chromium
and copper; approximately 88 percent of lead; approximately 95 percent
of zinc; and approximately 99 percent of iron.
The lagoon has a detention time of ten days, thereby providing an
equalizing effect. That is, the effect of the lagoon is to dampen the
peaks and to minimize shock loadings on subsequent treatment units. For
example, during the period in which the lagoon was included in the
treatment sequence, the 99 percent confidence interval for ammonia in
the raw leachate was 241-1285 mg/liter; while during the same period
the.lagoon effluent 99 percent confidence limit was 210-425 mg/liter.
Thus, the equalization effect is significantly beneficial in terms of
lessening shock loadings.
-2-
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System 1 has provided the best degree of treatment to date. This
sequence consists of lime precipitation/clarification/air stripping/
neutralization/phosphorus addition/activated sludge. In this opera-
tional configuration, excellent removal efficiencies ha^e been observed
following the adaptation of the activated sludge to the waste. In all
cases except Nfty-N, these effluent concentrations comply with the
effluent criteria developed by the Pennsylvania Department of Environ-
mental Resources and the Delaware River Basin Commission for discharge
to the Delaware River. A summary of the data is presented in Table 1.
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TABLE 1
SUMMARY OF SYSTEM 1 OPERATION DATA
Parameter
Ammonia-N
BOD5
Cadmium
Chromium
COD
Copper
1 ron
Lead
Mercury
Nickel
Zinc
Raw
Leacliate
mg/1
510
4993
0.049
0.105
9689
0.313
205
0.545
0.015
0.52
3.64
Final
Effluent
mg/1
46.5
60.5
0.014
0.075
576
0.078
0.96
0.12
0.004
0.27
0.44
Percent
Remova 1
90.9
98.8
71.4
28.6
94.1
75.1
99.5
78.0
73.3
48.1
87.9
Discharge
Standard
mg/1
35
100
0.02
0.1
*
0.2
7.0
0.1
/ .01
A
0.6
*No discharge standard for this parameter.
-4-
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DEMONSTRATION OF A LEACHATE TREATMENT PLANT
R.L. Steiner, J.D. Keenan, and A.A. Fungaroli
1. INTRODUCTION
The pot2"tia1 for water pollution from sanitary landfill sites has
become recognized in recent years. A number of studies'"^ have docu-
mented the great pollutional strength of landfi!! leachates. The quali-
ty of this material varies with landfill age, nature and moisture con-
tent of the wastes disposed at the site, and hydrologic and soil factors.
In spite of this variability, it can be stated that, especially for
young landfills, the values of the critical sanitary parameters of
leachate are at least an order of magnitude greater than for domestic
sewage. The deleterious consequences following contamination of ground
and/or surface waters by leachate may be severe, and it is for this
reason that leachate treatment is receiving attention.
Solid waste consists of matter which can be decomposed by bacterial
or microbial action, as well as of materials which are inert to micro-
biological activity. Some of the compounds, cellulose in particular,
are resistant to biological breakdown, but with sufficient time decompo-
sition will occur. Because of this resistivity and necessity to accli-
matize the biological system, the chemical characteristics of leachate
are t interdependent. To complicate treatment, as the paper decomposes,
some of the inorganic ions which are bound to the organic matrix are
released and can be removed by water percolating through the landfill.
The actual mechanism of removal varies with the component but includes
solution as well as colloidal transport.
The generation of leachate in landfills is complicated and
cannot be generalized simply as surface water percolating through the
sanitary landfill. When refuse is placed in the landfill, decomposition
begins to occur. Some decomposition products may be water soluble where-
as the parent products might not have been. This is especially true of
cellulose. In addition, the inorganic constituents also must be con-
sidered since they vary with the state of decomposition. The amount
of water percolating through a sanitary landfill is the primary control
of leachate quality, but the chemical characteristics of the leachate
are dependent on other parameters, including temperature, waste compo-
sition, moisture content, time, mode of decomposition (aerobic, etc.)
and the amount of infiltration of rainfall at the landfill.
-5-
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Recent studies have shown that leachate is produced in a sanitary
landfill when the precipitation exceeds the net evapotranspi ration of the,
region. Remson, FungaroJi, and Lawrence developed a model for predicting
the movement of leachate through a sanitary landfill. Further results
using this model have substantiated the validity of the approach and
prediction of leachate generation patterns is reasonably accurate.
Ground and surface waters can be protected if the landfill is under-
lain with an impervious membrane. With proper design, leachate is then
directed toward collection points. A waste such as this, which is pro-
perly considered an industrial waste, must be treated prior to surface
discharge. The leachate treatment state-of-the-art is still embryonic,
although a few small scale studies have been conducted. These have de-
monstrated that neither conventional chemical treatment nor biological
treatment can achieve the high degree of treatment efficiency expected
today. Consequently, although we know that the pollution potential of
sanitary landfill leachate can be avoided by interception using imper-
vious .liners, we are not yet able to define the optimum sequence of unit
operations and processes required for adequate wastewater renovation.
The U.S. Environmental Protection Agency, Office of Solid Waste
Management Programs, has awarded demonstration grant (S-803926) to
investigate the effectiveness of alternative treatment sequences as
employed at the full-scale facility in Falls Township, Pennsylvania.
A 380 liter per minute (0.144 gpd) plant had been constructed to treat
leachate from the GROWS (Geological Reclamation Operations and Waste
Systems, Inc.) landfill. This project has as its primary goal the
evaluation of the technical feasibility, operational efficiency and .
cost effectiveness of four alternative treatment sequences. These
are: (l) chemical/physical followed by biological; (2) chemical/physi-
cal alone; (3) biological followed by chemical/physical; and (4) bio-
logical alone. The chemical/physical processing includes precipita-
tion of heavy metals by lime addition, sedimentation, air stripping
of ammonia and neutralization using sulfuric and/or phosphoric acids.
Biological treatment consists of conventional activated sludge. Addi-
tional objectives of the study are the bench-scale evaluation of
carbon adsorption on both raw and unit process effluents; and bench-
scale testing to determine chemical dosage, sludge return rates,
aeration rates and other plant operating criteria.
-6-
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II. OVERVIEW OF LEACHATE TREATMENT OPTIONS
The purpose of this chapter is to review the literature regarding
the composition of sanitary landfill leachates and their treatment. In
brief, the character and variability of the leachate dictates the types
of treatment systems which will be effective. The contaminants of
greatest concern fall into several groups. The first group 3s the or-
ganic chemicals, important primarily because they exert an oxygen demand
on receiving waters which may result in a depletion of dissolved oxygen
deleterious to aquatic life. The second major group of contaminants
found in sanitary landfill leachates is comprised of the heavy metals.
As a group, these elements are of concern because they are toxic at
sufficiently high concentrations. It is conventional practice to chem-
ically characterize wastewaters such as leachate in terms of a number
of other parameters. These are used for a variety of purposes including
design, operational control, and evaluation o* pollution potential.
LEACHATE COMPOSITION
In 1932, one of the first studies indicating that the disposal of
solid waste could cause environmental pollution was reported by Calvert ,
who investigated the liquid waste from a garbage reduction plant in In-
dianapolis. In this process the garbage was cooked and the grease re-
moved to produce fertilizer and animal feed, and the liquid waste was
discharged into an impounding pit or lagoon. An analysis of this liquid
is presented in Table 2, Column 1. Calvert analyzed the groundwater
from existing wells surrounding the lagoon and found that wells up to
500 feet downstream of the site showed a marked increase in magnesium,
calcium, total dissolved solids and carbon dioxide.
Carpenter and Setter , working at New York University in 19^0, con-
ducted one of the earliest studies concerned with landfill leachate.
Auger holes were drilled through an existing landfill of undetermined
age into the subsoil. Twenty-eight samples of leachate which were col-
lected in the bore holes were analyzed chemically. The range of con-
centrations is presented in Table 2, Column 2. These results showed
a wide variation of concentration over the site, thus indicating the
difference of filled materials at various locations, or the differences
in the age of the refuse at different points. Analysis of groundwater
in the area was not performed, therefore the effect on the subsurface
environment was undefined.
The first comprehensive research study of sanitary landfills under
controlled conditions was conducted at the University of Southern Cali-
fornia^. Test bins, simulating landfill conditions, were constructed.
Water was added to simulate the infiItration .of 1.12 m and leachate was
collected and analyzed. Table 2 t,ives the minimum and maximum (Column
3) values of the initial (first 45-9 liters of leachate per cu m of com-
pacted refuse) leachate. The most rapid removal (the highest concentra-
tions) occurred with the first 232 liters per cu m of refuse. Thus, it
-7-
-------
was postulated that -emoval would continue for many years but at a very
slow rate, and it was considered unlikely that all the constituents
would ever be removed.
The same study also examined a field site consisting of 2.k m of
refuse and 0.61 m of coyer material. The refuse was in intermittent
contact with the groundwater, analysis of which showed increases in all
organic ions and a maximum biochemical oxygen demand of 125 mg/liter.
One conclusion of the study was that the dissolved inorganic ions en-
tering the groundwater through intermittent contact would decrease in
concentration as a result of dilution and adsorption and travel in the
direction of the groundwater movement.
The other conclusions reached in this study are summarized as
follows: (1) A landfill, if located so that it is in inter-
mittent or continuous contact with ground water, will cause the ground
water in the immediate vicinity of the landfill to become grossly
polluted and unfit for domestic or irrigational use; (2) dissolved
mineral matter, entering ground water as a result of intermittent and
partial contact of a landfill with the underlying ground water
will have its greatest travel in the direction of flow, undergo a ver-
tical diffusion to a limited extent, and be subject to dilution, the
result of which will be a minimizing of the effect of the entering
pollutant ions; (3) a landfill, if located so that no portion
of it intercepts the ground water, will not cause impairment of the
ground water for either domestic or irrigational use; (k) rainfall alone
(in the area of this study) will not penetrate a 2.3 m thick landfill
sufficiently to cause entry of leachate into the underlying ground water.
Longwell-* stated in 1957 that an appreciable proportion of refuse
could be extracted by water to produce a leachate rich in organic matter,
inorganic salts (ions), and/bacteria. The analysis of a surface leachate
obtained from an unnamed landfill is given in Table 2 (Column A).
In 1961 the British Ministry of Housing and Local Government con-
ducted 'extensive research on the placement of landfills above the ground-
water table ( which they called "dry tipping"), and the placement of
landfills below the groundwater table (which they called "wet tipping")6.
In the "wet tipped" experiment the refuse was completely submerged and
the horizontal groundwater flow rate was equivalent to 138 liters per sq
m per day. The leachate quality is included in Table 2 (Column 5).
Analyses of the groundwater before and after contact with the refuse
are given in Table 3- These results show the considerable extent of
groundwater quality degradation due to pollution by leachate.
In 19^5 Qashr studied the seepage waters from simulated landfills
at the University of West Virginia. Three concrete cylinders 0.9 m in
diameter and 1.2, 2.4, and 3-7 m in height were filled with municipal
-8-
-------
Table 2. THE STRENGTH OF RAW LEACHATES'
Acidity, »» C*tOj
AlUllnllr. *t Cȣ0j
AjMonl«-N
Aritnlc
•00-20
CilcliM
Cctbwt. Iot»l QrgMlc
I ,lorl.J«
coo
Copper
Cyan 14*
•lt»olv*d Oxy9*M
f (world*
M«r*in«it, •* C»COj
le*4
ntniM»ii
Nlc4«l
Hllrcl«-H
Nltrt|*-« * DUr»t*-H
•Itrofp*. Total
*TQ»«IC-»
HI .
PhotplMl**. f
kthatpliorM. Tool, i*
f of ml iff
SttJlMl
lift |f |[ fpn
$tflf*l«
Twtl •I»*olv«4 i*H*i
Tot»» Solids
line
0)
1.000-3. 30i
•7*
44.1
2.950
-
-
-
.
244
112
.
•
.
-
.
.
.
-
_
.
_
.
1.000*2.500
.
01
(3)
100-9.150
25-*, 000 730-9.500
0.2-480
6-7. 3JO
2I,700-)0,JOO
-
280-12.300
-
-
-
0-5.6
„
_
,
.
.
*
-
-
_
S. 7-8.4
.
.
.
^
,
"
'
-
94-2,350
.
-
-
.
890-7.600
7-220
64-410
.
-
-
-
2-US
4.0-4.5
0. l«Jj{
.
28*1, TOO
«5- 1.7*0
M-730
:
___r ~ _, ,__
(41
5%
97S
-
128
-
-
•
-
*
*?'
-
»
.
*
-
-
7
.
*
_
.
^
3
10
-
(5)
700
7.7*5
-
2.000
-
-
-
-
_
.
_
.
.
•
-
-
200
-
.
_
.
1.950
-
- _ . .
Averao* A^
0.5 yr.
(6)
a.'s
-
I.i97
19.680
0.05
0.024
-
.
7.130
5.500
.
1.16
-
1.70
-
_
.
1
.
.
900
Me
19.144
-
« or rill
6 yr.
(7)
0.1
0.8
14.080
-
1.110
8,000
0.05
0.005
-
I
2.200
.
o.ot
-
0.70
-
.
6.)
o!%
.
610
I
«.;»
•••I.,
>UlDrl.4<7
40-19.520
0-9.9
.
-
-
0-22,100
0-2.120
17-15.600
0.09-125
-
-
0.2-10.29
-
-
1. 7"6.5
6.5-65
0-1)0
26-3.7?*
0-7.700
1. 110-16. 6*0
1-1.556
10- 7M
5»4-4*.900
0-59.200
•-170
•«>•. 2
- I'.?)
142-1,520
1.4-1,026
1.9-57.000
76-1.900
70-27.700
60.2-2,467
11. 1-71. 660
-
-
-
0.5-2,200
55- 1.140
-
-
0.4' 10.29
-
-
5.09-7.25
0.15-65
».5-9§
15-1.300
44-1.56*
976- 16, 6**
7.4-1.556
8.9-921
911-55.346
:
*W»'
560
155
4. WO
550
1.400
470
1,000
-
-
-
.
440
210
.
-
-
1.5
-
•
5.91
3.2
9
a»
2 «0
4.970
90
197
4,0«0
••(•rwc* Do.
*STEINER, R.L. Chemical and Hydraulic Characteristics of Milled Refuse. Ph.D.
Thesis. Drexel University, Philadelphia, Pennsylvania. 1973.
CHIAN, E.S.K. and F.B. DeWalle. Sanitary Landfill Leachates and Their Treatment.
Proceedings ASCE, Journal of the Environmental Engineering Division 102, EE2,
411-31. 1976.
+A11 units are mg per liter except pH (pH units) and specific conductance (ymho/cm)
-------
Table 3
EFFECT OF SOLID WASTE DISPOSAL ON GROUNDWATER QUALITY
GROUNDWATER QUALITY BEFORE AND AFTER INTRODUCTION
OF "WET TIPPED" LANDFILL - 1961*
Concentration (tng/1)
Measured Quantity
Total solids (residue)
Chloride
Alkal inity, as CaCO,
Sulfate
Biochemical oxygen demand (BODc)
Organic nitrogen
Upstream of
Landfill
.50
30
180
120
0
0
Downstream of
Landfill
5,000
500
800
1,300
2,500
70
i . J —
^MINISTRY OF HOUSING AND LOCAL GOVERNMENT. Pollution of Water by Tipped
Refuse. Her .Majesty's Stationery Office, London. 1961.
-10-
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Table 4
EFFECT OF LANDFILL DEPTH ON LEACHATE COMPOSITION AND
POLLUTANT REMOVAL AT THE UNIVERSITY OF WEST VIRGINIA - 1965-
Concentration (mg/liter)
Parameter
Alkalinity, as CaCO
Bicarbonate
BOD5
Chloride
Hardness, as CaC03
Nitrogen, Total
Sodium and Potassium
Sol ids, Total
Sulfate
0.76 m
Fill
10,630
—
14,760
951
7,600
613
1,634
21,140
— ™
1.98 m
Fill
16,200
—
26,200
2,000
13,100
1,389
3,963
49,800
« mt
3.1 m
Fill
20,850
--
33,360
2,310
10,950
2,508
5,109
59,000
«•«_
Pollutant Removal (kg
0.76 m
Fill
™ •»
9.4
12.7
0.8
2.8
0.6
22.0
,..
0.5
1.98 m
Fill
— _
7.1
10.6
0.6
1.8
0.6
16.6
—
0.3
per cu m)
3.1 m
Fill
.„
5.9
9.0
0.6
1.1
0.6
14.4
—
0.2
•O.ASIM, S.R. Chemical Characteristics of Seepage Water from Simulated Landfills.
West Virginia University, Morgantown. 1975.
Ph.D. Dissertation,
-------
refuse. Approximately 102 cm of precipitation was artificially added
to the cylinders over a period of 6 months and leachate samples were
collected. The maximum concentrations of certain organic and inorganic-
components in the leachate from the three cylinders are presented in
Table A. Table 4 also presents the total weight removed per
cubic meter from each depth of fill by 102 cm of simulated infiltration.
A summary of results presented by Qasim demonstrates the effect of
depth on leachates generated by landfills. Concentrations of various
pollutants were higher in leachates obtained from deeper fills. Concen-
trations of various pollutants per unit depth of fill decrease with in-
creasing depths of refuse. For an equal amount of influent, shallower
fills showed greater extraction rate per unit volume of fill than deeper
fills. The bulk of the pollution was attributed to initial leaching.
Q
Anderson and Dornbush conducted an extensive investiqation of the
groundwater leaving a landfill in Brookings, South Dakota in
1967. An abandoned gravel pit of 160 acres with its base well below the
water table was filled with municipal solid waste. The purpose of the
investigation was to determine which chemical parameters were the most
reliable indicators of the influence of landfills on the groundwater.
Groundwater samples from 22 wells located over the site were analyzed
for chloride, total hardness, alkalinity, sodium, pH, potassium, iron,
nitrate, and specific conductance. A considerable increase in all con-
stituents measured was observed in three wells immediately downstream of
the fill area. Although the authors did not evaluate the potential pollu-
tion of municipal refuse, they did report an increase of up to 50 times
the chloride content of native waters in the groundwater affected by the
leachate. The major conclusion of this investigation was that two of
the most important indicators of pollution from landfills are chlorides
and specific conductance or total dissolved solids. Chloride ions are
easily detectable, not readily absorbed by soils, not affected by bio-
logical processes, and apparently an abundant product of leachates.
Disposal sites in northern Illinois were investigated in 1970 by
Hughes, e£ a_l_.° Leachate samples from three landfills of varying age
were obtained as near to the base of the refuse l?yer as oossible. The
results of these analyses are presented in Table 2 (Columns 6-8)
Although no information is given in the study as to the composition of
the solid waste in each fill, and the analyses were performed on only
one sample, the results do show a decreasing trend with time. However,
it was noted that refuse more than 15 years of age can still have a
high total dissolved solids content - indicating that the stabilization
of landfills is a long process.
The laboratory simulated landfill or lysimeter study conducted at
Drexel University from 1967 to 1972 is the only study reported that was
conducted under completely controlled laboratory conditions. It was
also the only study reported in which the. environmental conditions com-
pletely simulate the existing climatic conditions of a region, in this
-12-
-------
case, southeastern Pennsylvania. The refuse was placed at as received
moisture content and allowed to reach field capacity naturally through
the addition of amounts of distilled water equal to the precipitation
of the area minus the evapotranspiration. This infiltration was added
on a weekly basis and varied from a rate of 8.9 cm per month during the
wet periods to zero during the dry or summer periods. Approximately
one year was required for the refuse to reach field capacity, but small
quantities of leachate were generated before field capacity was reached.
The maximum concentrations obtained in the first year are given in Table
2, column 9 .
It was concluded that this initial leachate production came from
the following sources: (l) From the refuse. Most of the initially
generated leachate is squeezed from the organic components of the refuse
by the compaction and placement procedure. (2) From channeling. Some
of the water added at the top of the lysimeter may find a direct route
through the refuse to the collection trough, cue to any inhomogeneities
in the refuse. (3) From an advanced wetting front. The wetting front
in the refuse probably moves as a broad band rather than as a single
line interface. As a result, substantial increases in leachate will
occur before the entire system is at field capacity. CO From the main
wetting front. This is the leachate which is produced when the system
reaches field capacity. At this time, the input water and the output
leachate quantities become approximately equal.
Other studies have mentioned the leachate problem of refuse dis-
posal in papers dealing with other aspects of the solid waste problem.
Leo Weaver has stated that municipal refuse can generate leachates high
in organic pollutants.11 Data from this study are included In Table 2
(column 10).
Engineering Science in a study conducted in 196? in southern Cali-
fornia concluded that groundw/ater pollution, which may arise from re-
fuse leachate reaching a water source, will be shown largely as an in-
crease in total dissolved solids and specific conductance. *
Walker in 1969 found that a sand and gravel aquifer in Illinois was
ineffective in removing dissolved chemical ions generated by a landfill. *
He did report that travel of leachate through a short distance (3 to 5 m)
of this aquifer will remove organic pollutants generated by landfills in
Illinois and concluded by stating that inorganic pollutants constitute
the greatest source of concern.
Roessler noted an increase In Inorganic pollutants in an industrial
water supply 2£ miles downstream from a refuse dump 10 years after tho
dump had started operation.'^ Lang noted that a dump containing primar-
ily garbage polluted wells approximately 2,000 feet downstream.'5 He
observed increases in inorganic pollutants such as total dissolved
solids, hardness and chloride, and concluded that refuse dumps can
cause a 100% increase in the inorganic pollutants In wells up to 2,000
feet away.
-13-
-------
Table 2 (columns 11-13) presents a summary of values of raw
leachate composition as compiled by Chian and DeWaile.'° The ranges
represent leachates examined by a number of investigators (Range 1-
Column 11) and a variety of leachates studies at the University of
Illinois (Range 2-Column 12). These data are the results of a re-
cently completed literature review.
The conclusion to be drawn from this review of landfill leachate
quality (as summarized in Table 2) is'that its composition is highly
variable from site to site. In addition, the data show that even at
a given landfill, considerable variation is encountered with respect to
both space and age. That is, variability is a factor within a landfill
and also over the history of the site. Consequently, it is concluded
that landfill leachate quality cannot be predicted a prior?; and that
this quality is even variable at a given site.
LEACHATE TREATMENT
Leachate treatment systems have been evaluated on a laboratory-
scale at Drexel University. In one study'?, the purpose was to character-
ize the biodegradation of organic matter both with and without the supple-
mentary addition of chemicals. The system consisted of five aerobic
units which were treated in the following manner: (l) control-no
treatment; (2) addition of sodium hydroxide to pH 9; (3) addition of sodium
hydroxide to pH 11; (k) addition of lime; and (5) addition of lime plus
sodium carbonate. Otherwise, all units were handled in the same manner.
This procedure included preparation of an activated sludge culture by
aerating leachate. Each experimental unit was seeded with this culture
and was aerated at a rate of 3k liters of air per gram COD (1500 cu ft per
Ib COD). During the testing, all settled solids were recycled to the
aeration tank with no sludge wastage. The aeration treatment systems
were operated on a continuous basis with a hydraulic residence time of
five days. /
The COD values decrease quite rapidly during the first six days
and thereafter approach a limit. The results indicate that there are
components of leachate which are not amenable to treatment in an aerobic
system. The time of adaptation of microorganisms for treatment of the
organic fraction of leachate may be considerably longer than normal sewage.
Volatile solids concentrations in these tests were low when compared to
normal activated sludge systems. This may be one reason for the long time
required for stabilization.
Figure 2 shows the high variation in the concentration of total dis-
solved solids in the treated effluent. The cyclic variation of
-------
3000
en
2000
q
u
Figure 1. Reduction in COD during
aerobic treatment'?
1000
Treatment
10
14 18 22
Time (Days)
26
30
-------
Figure 2. Changes in Total Dissolved
Solids (IDS) during aerobic
treatment studies '
15 20
Time (Days)
25
30
-------
several systems is of interest, but not all of the systems show this
phenomenon. Since the withdrawal and addition of leachate was constant,
there was no reason for the cyclic effect. Only pretreatment with lime
gave any type of stability and COD reduction.
Thus, neither biological waste treatment nor chemical-physical
treatment separately is able to reduce the BOD more than eighty per-
cent. In fact, the efficiency of the chemical-physical process is con-
siderably below this level. It is hypothesized that two reasons exist
for the poor removal efficiency of each individual system: 1) the large
percentage of high molecular weight organic materials, and 2) the bio-
logical inhibition caused by heavy metal presence. The physical-chemical
treatment is needed to remove the metals and also to hydrolyze some of
the organics, and biological treatment to stabilize the degradabie
organic matter.
In addition, biological treatment alone does not remove significant
amounts of the heavy metals. In fact, biological units may be inhibited
due to the toxic effects of the metals. Consequently, chemical and/or
physical processing is needed for the removal of substantial amounts of
these materials. Lime treatment is particularly effective in that it
creates the alkaline conditions under which the metals become insoluble.
The removal of heavy metals during lime precipitation depends upon
the formation of insoluble metal compounds, primarily hydroxides, at
alkaline pH. The optimum set of conditions is not identical for all
metals, and the result is that it is impossible to achieve the maximum
theoretical removals for each metal within a single tank. In general,
the optimum pH levels are in the range of 7"10.3 (see Table 5).
Hexavalent chromium is not removed by lime addition unless it has pre-
viously been reduced to trivalent chromium.
These studies demonstrated that the aerobic treatment of sanitary
landfill leachate is feasible and that pretreatment may be required.
Lime precipitation appears to be the most favorable pretreatment method.
The organic fraction of leachate was found to contain substances not
readily assimilated by the microorganisms, and it was hypothesized that
chemical treatment is needed to remove these organics.
Chian and DeWalle have recently completed an extensive review of
leachate treatment techniques.'" Their conclusion was that leachate
collected from recently leaching landfills is best treated biologically.
This is because the organic fraction of such leachate is composed pre-
dominantly of free volatile fatty acids which are readily biodegradable
by either aerobic or anaerobic means. On the other hand, leachate from
older landfills is more efficiently handled by chemical-physical pro-
cesses, because these organics are more resistant to biodegradation.
They also concluded that activated carbon and reverse osmosis were the
most efficient chemical-physical methods in terms of the removal of
organics.
-17-
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Table 5
THEORETICAL REMOVAL OF HEAVY METALS DURING LIME PRECIPITATION*
Theoretical Effluent
Metal Optimum pH Concentration, mq/1
Cadmium 10 1.0
Hexavalent chromium
Trivalent chromium 8.5"9-5 <1
Copper 9.0-10.3 0.01
Soluble iron 7
Lead — <0.1
Nickel 10 0.01
Zinc — <0.1
"PATTERSON, J.W. and R.A. Minear. Wastewater Treatment Technology.
Prepared for Illinois Institute of Environmental Quality. 279 pp.
Published by NTIS, Springfield/, Va. PB 204 521. 1971.
-18-
-------
The compilation of data presented by Chian and DeWalle indicate
the following range of COD removal efficiencies for various treatment
methods: 0 to 98 percent for aerobic biological; 87 to 99 percent for
anaerobic biological; 17 to kO percent for aerobic/anaerobic biological;
0 to 40 percent for chemical precipitation with alum, ferric chloride,
ferrosulfate or lime; 3*» to 9^ percent for activated carbon and ion-
exchange; 0 to ^8 percent for chemical oxidation; 56-98 percent for re-
verse osmosis.^°
As a means to bring order to the wide disagreement found, in the
literature, Chian and DeWalle postulated the age of the landfill affected
the character of the leachate, and that this character is best measured
in terms of the ratios of chemical oxygen demand to total organic carbon
(COD/TOC) or of biochemical oxygen demand to chemical oxygen demand
(BOD/COD) (Table 6)16.
SUMMARY
The state-of-the-art concerning the composition and treatment of
sanitary landfill leachates has been assessed. The most obvious char-
acteristics of leachate are its strength and its variability. Leachate
is generally of much greater strength than domestic sewage. This is
especially true in terms of organic materials and the potentially toxic
heavy metals. As important a characteristic as strength is the varia-
bility of leachate composition. Leachate quality not only fluctuates from
landfill site to sit2, but also from time to time at one landfill. Changes
over time result from differences in seasonal hydrology and microbiologi-
cal activity. Rainy weather may dilute the leachate, but, at the same
time, may flush out large quantities of pollutional material. The typi-
cal pattern observed over many years is that the pollution potential of
leachate is greatest during the first five years or so after placement,
but that leachate strength remains significant for as long as ten to
twenty years. This sequence is encountered because the microbiological
processes responsible for the decomposing of the solid wastes are rela-
tively slow acting and are first directed at the most readily biodegrad-
able components of the waste.
Considerable differences are encountered in leachate quality when
comparing landfills. In addition to the seasonal, hydrologic and age
of landfill factors mentioned above, there are several other reasons
for this observation. The chemical nature of the wastes accepted at
the landfill has a marked effect on the composition of the leachate.
The land disposal of industrial liquid and solid wastes is critical
in this light.
The variability and the strength of leachate have important waste
treatment implications. First, the sheer magnitude of the measures of
pollution potential dictate the use of thorough waste treatment. Second,
the changes encountered from landfill to landfill are such that waste
-19-
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Table 6
LEACHATE TREATABILITY AS HYPOTHESIZED BY CHIAN AND DeWALLE*
COD
TOC
>2.8
2.0-2.8
<2.0
Leachate Qual i ty
BOD
COD
>0.5
3.1-0.5
<0.1
Age of
Fill
Young
(<5 yr)
Med i urn
(5 yr-10 yr)
Old
(>10 yr)
COD,
mg/1
>10,000
500-10,000
<500
Treatment Eff
to
o
•_
CD
O
o
eo
G
F
P
c
o
4->
10
— 4J
(0 —
O Q.
•— •—
£ 0
o>
— (0
E T3
ID .—
JC X
0 O
P
F
F
c
O
4-1
to
o
N
O
P
F
F
iciency+
0) in
in .-
i- w
a) O
> c
0) tt
oe o
F
G
G
•o
O
— .0
4-> 1-
O (D
< 0
P
F
G
0)
O)
c
ID
.C
c o
0 X
— LU
P
F
F
I
N>
O
j.
CHIAN, E.S.K. and F.B. DeWALLE. Sanitary Landfill Leachates and their treatment.
Proceeding ASCE, Journal of the Environmental Engineering Division 102, EE2, ^11
1976.
+(G = good; F = fair; P = poor)
-------
treatment techniques applicable at one site are not necessarily directly
transferable to other locations. That is, it may be mandatory that each-
instance be separately engineered to achieve adequate treatment. Third,
the fluctuations in leachate quality which occur over both short and
long time intervals must be accounted for in the treatment design. Not
only must processes be designed to efficiently treat the waste flow from
minute to minute, but the design must also reconcile the possibility
that treatment techniques which work well for a young leachate may be-
come wholly inadequate as landfill age increases.
It is apparent today that most landfill leachate cannot be
treated adequately by just conventional chemical/physical treatment or
conventional biological treatment. Rather, what is needed is a com-
bination of the two approaches with perhaps a supplementary form of ad-
vanced wastewater treatment. The purpose of this project is to inves-
tigate, at both the full and bench-scale levels of operation, the effi-
ciency of treatment afforded by these processes.
-21-
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III. LEACHATE TREATMENT SYSTEM
The leachate treatment facility being used in this study is located
at the GROWS Landfill in Tullytown, Falls Township, Bucks County, Penn-
sylvania (see Figure 3). The plant is designed to provide maximum opera-
tional flexibility in order to permit full-scale testing of a variety of
treatment sequences. Plant design and treatment modes are considered in
subsequent paragraphs.
The sanitary landfill has a surface area of 50 acres. The landfill
will be filled with about 1,400,000 cu m of refuse over the next several
years. The time required to fill the landfill depends upon many unknown
factors, but it is estimated that it will probably be between five and
ten years. The receipt of refuse is about 800 tons per day. Eighty-
five percent of the refuse is from municipal sources. The remainder is
industrial and commercial. The landfill is also permitted to accept
sewage sludge and selected industrial liquid wastes.
The landfill is located in the semi-humid northeastern part of the
United States. The ninety-eight year monthly average precipitation and
temperature data are given in Table 7- In this region there is a net
positive infiltration of rainfall into the landfill. As long as there
is a net positive infiltration, leachate will eventually begin to be
produced by the landfill.
Because of these meteorological conditions and the site hydrologic
situation, groundwater pollution potential existed. To alleviate this
pollution potential the Pennsylvania Department of Environmental Re-
sources required the landfill to be underlain by an impervious asphaltic
membrane. This membrane system was designed to collect and transport
the leachate to the leachate treatment plant/.
The treated effluent is discharged to the Delaware estuary. The
river zone is tidal and flow figures are not available. At the nearest
gage (Trenton) the drainage area is 6700 square miles and the projected
low flow is 33,000 liters per second. The discharge of treated effluent
directly to the Delaware River occurs only during the months of December
through April. During the remainder of the year, the effluent is re-
turned to the landfill. The landfill has ample storage capacity In
the pore space so that storage for six months does not create any diffi-
culties. The effluent is spread on the landfill using aeration nozzles.
The treatment plant operates under permits from the Commonwealth of
Pennsylvania Department of Environmental Resources Water Quality Section
and the Delaware River Basin Commission. The effluent criteria for the
facility are summarized in Table 8.
-22-
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Table 7
Precipitation and Average Monthly Temperature Data
Trenton, New Jersey*
Month'
January
February
March
Apr! 1
May
June
July
August
September
October
November
December
Total
Rainfal 1
cm
8.87
6.58
9.75
8.15
9.19
9.1**
10.62
12.12
8.89
7.21
8.03
7.29
104.85
in.
3.10
2.59
3.84
3.21
3.62
3.60
4.18
4.77
3.50
2.84
3.16
2.87
41.28
Temperature
°C
0.8
1.0
5.1
11. 1
16.9
21.7
24.2
23.3
19.6
13.5
12.7
1.7
°F
33.4
33.8
41.3
52.1
62.7
71.4
76.0
74.3
67.6
56.5
45.1
35.1
Trenton, N.J. Weather Bureau, 30 Year Average.
-23-
-------
Figure
Location of Lwehat* TrMtwnt Plant
Newbold Island
:L'D
ROAD CIJSSiriCATION
Mtduin-duty — ._>_ Unimpronctf 4M
Qu.SRouH
TRENTON WEST, PA.— N. J.
Cl'.".-.":Ur LOCATION
-------
Table 8
EFFLUENT
GROWS SANITARY LANDFILL LEACHATE TREATMENT FACOLITY
SUMMARY OF EFFLUENT CRITERIA*FOR
Parameter
BOD
Ammon 5 a -Nitrogen
Phosphate
Oi 1 and grease
I ron
Zinc
Copper
Cadmium
Lead
Mercury
Chromium
Maximum Concentration
mg/1 iter
100.0
35.0
20.0
10.0
7.0
0.6
0.2
0.02
0.1
0.01
0.1
>vCommonwealth of Pennsylvania Department of Environmental
Resources and Delaware River Basin Commission.
-25-
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Design Overview
The purpose of this section is to briefly summarize the design
criteria and to discuss the design itself of the treatment facility.
The effluent limits have been mentioned above and presented in Table
8. The following paragraphs are devoted to a discussion of the .leachate
quantity and quality as estimated for design purposes.
Design Flow
The source of liquid waste is the leachate which results from the
degradation of refuse and percolation of rain water through the
landfill. In addition, as the treated effluent is recycled to the
landfill during the summer months, and to the Delaware River during
the winter, the raw leachate volume includes this recycled effluent.
The quantity of waste which is generated is dependent upon many indivi-
dual factors of the landfill. The maximum generation of waste (includ-
int the recycled volume) for design purposes was estimated to be about
20 liters per sq m-week at this site. However, the production of
leachate is dependent upon the time cycle, both as to placement and to
the season of the year. Leachate itself occurs as the result of the
excess of infiltration over evapotranspiration and the soil moisture
deficit. Thus, the actual generation of leachate depends upon precipi-
tation patterns, landfill moisture and effluent recycling.
Since the generation of leachate is a function of the age of the
fill, not all the expected leachate will be produced simultaneously.
There is an initial period of operation when the landfill comes to
field capacity, followed by an extended period of leaching of contami-
nants, after which there exists a state of degradation when the leachate
is no longer of a polluting nature. It is possible that some portions
of the landfill will be in this latter state when the final parts of ,the
landfill are being completed. Hence, the maximum flow of 20 liters p*er
sq m-week is a value which may never be attained for extremely strong
leachate. This maximum flow rate was determined using the site meteoro-
logical data presented in Table 7 and the procedure developed by Remson,
Fungaroli and Lawrence .
Design Leachate Characteristics
The leachate strength parameters used for design purposes are
presented in Table 9. These were obtained through a modest sampling
program conducted during the very early stages of the landfill. How-
ever, as discussed in Chapter II, the exact character of waste is diffi-
cult to predict for a number of reasons, including the fact that it is
subject to dilution when the infiltration is high. In addition, be-
cause of the on-site variability, it is possible that single samples do
not accurately reflect the character of the waste.
-26-
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Table 9
DESIGN LEACHATE CHARACTERISTICS
Constituents Raw Leachate*
BOD 1500
Suspended Solids 1500
Total Solids 3000
Percent Volatile 55
pH, pH units 5.5
Chlorine 200
Iron, total 600
Zinc 10
Chloride 800
Organic Nitrogen 100
Nitrate 20
Sulfate 300
Copper 1
Hardness 800
Alkalinity 1100
Color, standard units 50
Flow, mgd ,\kk
Temperature, °F / 80
*A11 units are mg/1 except pH, color,
flow, and temperature.
-27-
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Design Concept
As discussed -in Chapter II, a combination of chemical/physical
treatment plus biological treatment is often required for leachate treatment.
The principle is that the chemical/physical units can be used for the
removal of refractory organics and for pretreatment prior to the
biological process. In the latter case, the chemical/physical processes
are used for the removal of potentially inhibitory materials such as
heavy metals and ammonia-nitrogen. The function of the biological units
is the stabilization of organic matter and the oxidation of ammonia
nitrogen. As a result of the findings discussed in Chapter II and the
design leachate quality, this treatment plant was designed to consist
of lime treatment and sedimentation followed by activated sludge and
chlorination. Air stripping of ammonia and nutrient addition are in-
cluded in the chemical/physical section. A schematic of the leachate
treatment plant appears as Figure ^.
Leachate Collection System. The raw leachate is contained within the
lined landfill which was designed to allow tor the collection by gravity
of leachate at three locations. These locations are outfitted with man-
holes from which the leachate is pumped and transported via pressure
lines to the treatment facility. The leachate enters the plant via a
one thousand gallon holding tank in which little mixing occurs because the
from the individual manholes is highly variable, and pumped sequentially.
Chemical/Physical Section
The chemical/physical portion of the plant consists of the following:
chemical precipitation and coagulation, sedimentation of precipitate,
air stripping at elevated pH for ammonia removal, neutralization and
nutrient supplementation. Each of these are discussed in the following
paragraphs.
Chemical Precipitation. In the chemical treatment phase, the major design
goal was the removal of inorganic materials. In particular, metals that
may interfere with the subsequent biological treatment process are removed;
also, the metals are removed to achieve discharge standards (Table 8).
As part of the chemical treatment, the biochemical oxygen demand will also
be reduced, but the design percentage of reduction was 30 to 50 percent,
on the basis of the experience with municipal wastewater and with leachate
as discussed in Chapter II.
The chemical treatment step consists of flash mixing followed by
quiescent conditions favorable for coagulation as well as sedimentation
of the chem'cal sludge. Lime has been the only chemical utilized in this
chemical precipitation step. However, additional feeders and points of
injection have been provided for the use of other chemicals if necessary.
Other chemicals which might be used include alum, ferric chloride, synthe-
tic polymers, and powdered activated carbon.
This unit is an upflow solids contact reactcr clarifler. Lime
slurry is added to cause coagulation and precipitation of the waste
-28-
-------
Figure
SCHEMATIC FLOW SYSTEM t\ WITH AMMONIA STRIPPING LAGOON
Unit volumes are shown In cubic meters (I cu m <• 1000
liters - 264.2 gal • 35-3 cu.ft)
Manhole
l
to
Sludge — *^->.
Holding 7 \. Waste Sludge
I J*- ' • • • "|
21 cu.rorA.^/ . .
* . 1
v 1
^ | Settling
~ 1 j 23.7 cu. m. each
& -in
35.8 cu.nh — ^^x — ' — v
w
/ Reactor \
k J ri,,tti~, \
Pump \ y
f^ /
f ^w^ ^S ^^'
/
Line
75.7lcum /» Chlorine r- 7.6 cu. m.
Aeration '/ > i Contact X
CLanhor 1 . „ .. to
/ > River v
75 71 r,, m / Or
1 Landfill
Aeration ' — *~~^
Chamber
1 Sludge j
H2SOj,
Lagoon
950 cu at
-------
materials. The time is pumped at a rate commensurate with the rate of
leachate production. The lime slurry is 'flash mixed with the incoming
waste, and mixing, flocculation and upflow clarification occur within a
single unit. Solids contact is optimized by variable sludge recycle.
The chemical treatment facility is a 3.66 m diameter, 3-66 m deep
cylinder with a hydraulic retention time of 1.7 hours at 380 liter/min
flow rate.
Sludge is drawn off the bottom of the reactor clarifier and placed
in a common sludge holding tank with the waste activated sludge. Sludge
return pumps are available to recirculate the sludge and mix it with the
incoming waste water to reduce the amount of chemicals which are needed
for precipitation. (However, the practice to date has been to use lime
and to not recirculate the sludge.). The amount of sludge that is pro-
duced in this step depends upon the composition of the leachate. The
design projection was that approximately 5 percent of the flow will be
produced in sludge at 1 percent solids concentration.
Air Stripping of Ammonia. As a means of controlling excessive levels of
ammonia in the lime treated stream and in the final effluent, a lagoon
incorporating air stripping of ammonia is included in the chemical/
physical section of the plant. The lagoon is located after the chemical-
precipitation-clarification unit in order to take advantage of the high
pH of the upflow solids contact reactor clarifier effluent and to mini-
mize the solids loading on the lagoon.
The volume of the lagoon is 950 cu m, thus providing a detention
time of approximately 1.74 days at design flow. The primary function
of the lagoon is to encourage air stripping of ammonia by an elevated
influent pH of 10, aeration and high internal recycle with splash plate
to increase the air/water interface. The lagoon is lined with chlori-
nated polyethylene. In addition to ammonia removal, the lagoon pro-
vides equalization in terms of both flow and sanitary parameters.
Neutralization and Nutrient Supplementation. Sulfurfc and phosphoric
acids are added to reduce the pH of the leachate prior to entering the
biological waste portion of the process. Phosphoric acid replenishes
the supply of o-phosphate, a necessary biological nutrient, which is
precipitated and removed following the addition of lime.
Biological Treatment Section
The biological treatment units consist of two aeration and two
secondary clarifiers. The units may be operated in series or parallel.
The capacity of each tank is 75,710 liter, which corresponds to a 6.6
hour detention time at the maximum flow rate of 380 liter/mln. The
aeration chambers are provided with diffused aerators, each driven by
a 14.2 cu m per min blower.
-30-
-------
Depending on the actual hydraulic residence time in the aeration
tanks, the activated sludge units were designed to operate in either the
conventional or extended aeration modes. In order to achieve this, the
mixed liquor volatile suspended solids (MLVSS) would be maintained in
the range of 3000-8000 mg/liter. This level is high relative to that
normally maintained in units handling municipal wastewater. However, it
is necessary because of the high BOD loading, and because of the require-
ment to remove about 90 percent of the BOD remaining after chemical/
physical treatment. The MLVSS is maintained by return sludge pumps
capable of delivering a return sludge flow equal to 200 percent of the
influent flow.
The waste sludge from the activated sludge units and from the chem-
ical treatment process are stored in the sludge holding tank. The capacity
of this tank is 21 cu m, and sludge is removed as required and conveyed
back to the landfill via tank truck.
Separation of treated wastewater from the MLVSS is achieved by
gravity sedimentation in the secondary clarifiers. The total clarifier
volume is 47,318 liter, in two parallel independently operable units.
Sludge return is provided with air lifts installed in the final settling
tank. A skimming device is located in the settling basin in front of
the scum baffle to remove floating material which will be returned to
the aeration compartment. The maximum surface overflow rate is 20.4
cu m per day per sq m (500 gpd/sq.ft.) based on the peak flow of 380
1iter/min.
Final effluent is directed to the chlorine contact tank after
secondary clarification. The chlorine contact tank provides a reten-
tion time of 20 minutes at the 380 liter/mfn flow rate. The effluent
after chlorination is discharged to the Delaware River or to the land-
fill depending upon the season of the year. The chlorine contact tank
is a simple baffled tank to assure mixing of the chlorine which is pro-
vided by hypochlorination.
-31-
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IV. MATERIALS AND METHODS
Experimental Systems
The leachate treatment plant, although designed for chemical/
physical treatment followed by biological treatment, was equipped with
sufficient flexibility to provide for operational evaluation of a var-
iety of treatment sequences. These sequences are each defined in the
following paragraphs with reference to Figure k.
System 1 - Chemical/Physical followed by Biological Treatment
System 1 is the basic treatment sequence with lime treatment for
metals removal followed by ammonia stripping and conventional activated
sludge. System la refers to the use of System 1 when the air stripping
was not used, whereas System Ib signifies that the lagoon was included
in the flow sequence. System la was tested in the late winter and spring
of 1976, and System Ib in the summer of 1976.
System 2 - Chemical/Physical Treatment
Two subsystems have been evaluated. These, Systems 2a and 2b, consist
of lime treatment either with or without subsequent removal of ammonia by
air stripping. The system without ammonia stripping (System 2a) was
evaluated in the winter and spring of 1976; and System 2b in the summer
of 1976.
System 3 - Biological followed by Chemical/Physical Treatment
This is the reversal of System 1. This system was studied during
the winter of 19/76. The results indicated poor treatment efficiency,
most likely due to heavy metal and ammonia toxicity. However, it might
be argued that a sufficient amount of activated sludge had not developed.
Therefore, System 3 will be reevaluated in order to test this latter
hypothesis.
System k - Biological Treatment
This system has been tested, the results showing poor treatment
efficiency. However, as indicated above, the performance might improve
if a previously acclimated activated sludge were available. Consequently,
System ^ will be operated and tested simultaneously with System 3-
Process Monitoring
An analytical laboratory has been established in a trailer located
immediately adjacent to the treatment plant. The trailer is outfitted
with the apparatus indicated below and is environmentally controlled
with a heating/air conditioning system. The need for extensive bench-
-32-
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Table 10
ROUTINE LABORATORY CHEMICAL ANALYSIS
Da i 1 y
Itxm
pH
Chemical oxygen demand
Dissolved oxygen
Mixed 1 iquor suspended sol
Method
Dichromate reflux
Electrode
ids Gooch crucible
Mixed liquor settleable solids Gooch crucible
Dissolved sol ids
Volatile suspended solids
Total residue
Alkalinity
Biochemical oxygen demand
Total hardness
Kjeldahl nitrogen
Ammonia nitrogen
Phosphate
Sulfate
Chloride
Total i ron
Chromium
Copper
Cadmium
Lead/
Mercury
Zinc
Nickel
Calcium
Magnesium
Sod i urn
Potassium
Oil S Grease
Gooch crucible
Gooch crucible
Gooch crucible
Weekly
Tltrimetric (pH 4. 5)
Probe ethod
Titrimetric
Ti trimetric
Distillation
Persulfate digestion
Gravimetric
Titrimetric
AA*
AA
AA
AA
AA
Mercury analyzer
AA
AA
AA
AA
AA
AA
Aperiodic
Hexane extraction
EPA
Storet
No.
00349
00299
70300
50086
00530
00520
00500
00410
00310
00900
00625
00610
00665
00945
00940
—
—
—
—
—
--
—
—
• ,
—
—
Detec-
tion
Limit
—
--
—
—
--
—
~™
—
--
--
--
--
--
—
— .
0.02
0.02
0.01
0.002
0.05
0.0002
0.005
0.005
0.003
0.005
0.002
0.005
*Atomic Absorption Spectroscopy
-33-
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scale testing and the large number of analyses needed for process con-
trol and monitoring made the on-site laboratory mandatory. The labora-
tory is operated by the chemist-operator employed specifically for this
project.
The chemical analyses performed routinely are presented in Table
10. These have been selected on the basis of four criteria: they
represent the most common chemical parameters used in the literature
to characterize landfill leachate; they provide sufficient data to com-
pletely evaluate the unit operations, process and total system effi-
ciency; they are needed for orocess control; and they are required to
specifically define the leachate. f
All analyses are performed in accordance with Standard Methods
13th Ed. 1971; ASTM Standards pt-23, 1972 and EPA Methods, 197*» EdJ9'21
The analyses are performed on total samples as opposed to filtrate
samples. Some preparation of the raw leachate is required.
Electrometric techniques are t'sed in the determination of dissolved
oxygen (with periodic checks using the Azide Modification of the WInkler
lodometric procedure), pH, and dissolved solids. Atomic absorption spec-
troscopy is used for iron, chromium, copper, nickel, zinc, sodium, cadmium,
lead, and potassium.
A number of sampling points are used in the analysis program.
Routinely, samples are collected of (1) the raw leachate; (2) chemical/
physical sedimentation tank effluent; (3) lagoon effluent; (k) mixed
liquor; and (5) biological sedimentation tank effluent. In addition,
samples are collected on an irregular basis from the three landfill man-
holes and directly from the individual treatment units. In all cases,
every effort is made to ensure that a representative sample is obtained.
Bench-Scale Testing
As a supplement to the full-scale treatment processing, some smaller
scale work has been undertaken. This effort serves two purposes. First,
it allows the operator to readily develop operational guidelines. For
example, jar tests have been used to determine proper chemical dosages.
The second purpose is to provide an opportunity for evaluating addi-
tional treatment techniques. Specifically, bench-scale testing has been
used to evaluate activated carbon treatment of raw leachate. Granular
activated carbon has been used in column studies to obtain performance
characteristics. The results are discussed in Chapters. Additional
carbon studies, as a final effluent polishing technique, will be under-
taken in the coming months.
-------
Statistical Tests
The following notation is used throughout: n, number of data points;
x, arithmetic means; and s, standard deviation. The mean is calculated
as
X = —
n
and the standard deviation as
s =
n-1
where the Xj are the n data points,
and the coefficient of variation is
cv = JL
x
The value of the coefficient of variation decreases with decreasing
variability.
-35-
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V. RESULTS AND DISCUSSION
Preliminary Results
Raw Leachate Quality
A summary of actual leachate quality is shown in Table II. These
data are a summary of the entire set of results. As is evident from a
comparison of Tables 9 and 11, there are significicant differences
between the two. These changes toward increased leachate strength are
seen mainly between the design and actual raw leachate organic matter,
dissolved solids, pH and ammonia. The biodegradable organics concentra-
tion is three times the design level. Dissolved solids are an order of
magnitude greater, caused by increased hardness, organic matter and
chloride. The ammonia concentrations actually observed have been ex-
tremely high and have been a source of operating problems especially in
the biological units. The factors influencing this difference between
the projected and observed leachate quality have been discussed in Chap-
ter II.
Considerable variabilfty in the raw leachate quality has been noted
on a day-to-day basis. The influent COD data are presented in Figure 5
to show this variability. An additional indication is provided by
the coefficient of variation data provided in Tablet, columns 3 and
10.
Lime Dosage
Jar tests were carried out in the laboratory in order to determine
proper dosages for the lime treatment unit. In the first series of tests,
three types of lime were monitored for their ability to raise the pH of
raw leachate to 10.0. The 1ime^ used were high magnesium lime, high
calcium quick lime and high calcium hydrated lime. The results may be
summarized as:
Dosage
lb/1000 gal kg/cu m
High Magnesium Lime 125 15
High Calcium Quick Lime 52 6.2
High Calcium Hydrated Lime 50 6.0
It is economically impractical to use the high magnesium because Its
properties are such that to raise the pH to 10.5 requires 30 kg per
cu m (250 Ib per 1000 gal).
Required cosages to obtain pH 10.0 are nearly Identical for both
types of high calcium lime. For pH greater than 10.0, the high calcium
quick lime becomes more efficient and hence is desirable economically.
However, the slaking characteristics of the quick lime have caused pro-
-36-
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Table II
LANDFILL LEACHATE CHARACTERISTICS*
I tern Concentration'*'
Biochemical oxygen demand (5-day) 4,460
Chemical oxygen demand 11,210
Total solids 1,154
Suspended solids 1,994
Dissolved solids 11,190
pH, pH units 7.06
Alkalinity, as CaCOj 5,685
Hardness, as CaC03 5,116
Calcium 651
Magnesium 652
Phosphate 2.81
Ammonia-N 1,966
Kjeldahl-N 1,660
Sulfate 114
Chloride 4,8l6
Sodium 1,177
Potassium 959
Cadmium 0.043
Chromium 0.158
Copper 0.441
Iron 245
Nickel ; .531
Lead .524
Zinc 8.70
Mercury .0074
*These values represent the arithmetic mean of all raw leachate data,
+A11 units mg/liter unless otherwise noted.
-37-
-------
GO
I
25-
FIGURE 5
RAW LEACHATE CHEHJCAL OXYGEN DEMAND
DEC. I JAN! ' FEB!'MARCH 'APRIL MAY ' JUNE JULY AUQ. SEPT.
1976
-------
blems with pumping the resultant slurry so that this lime cannot be used
with the available lime feed system. On the other hand, the hydrated
lime does not offer such problems, and consequently, the high calcium
hydrated lime is being used.
SuIfuric Acid Dosage.
The amount of sulfuric acid required to lower the clarifier efflu-
ent to 6.5 has been determined. To do this, approximately 0.6 ml of
concentrated sulfuric acid per liter leachate (0.6 gal/1000 gal) is re-
quired. The actual dosages used are presented later in this chapter
as part of treatment costs.
Phosphoric Acid Dosage
The need for a phosphoric acid supplement became apparent from three
lines of evidence: (a) very low phosphate levels in the chemical/physical
effluent; (b) unrealistically low values obtained in the biochemical
oxygen demand test; and (c) poor biological treatment performance follow-
ing the chemical/physical process.. These points all indicate that the
chemical/physical treatment effluent Is phosphorus deficient, and that,
if biological treatment is to follow, it must be supplemented with phos-
phorus. Additional evidence was collected by performing a series of
BODij tests in which a variable amount of phosphorus supplement was added
to the bottles. It was observed that the BOD increased with the amount
of phosphorus. In addition, bench scale tests indicated greater acti-
vated sludge production when o-phosphate was added. Thus, it has been
concluded that orthophosphate, as phosphoric acid, should be added to
form a nutrient supplement.
The preliminary calculation of phosphoric acid dosage has been made
on the basis of providing, a ratio of BOD:N:P of 100:5:1. This is approx-
imately 15-23 liter (4-6'gal) phosphoric acid per day. More recently,
however, the criterion is to add phosphoric acid so that there is measur-
able o-phosphate in the bio-unit effluent. This amounts to about 3-8
liter (1 gal) of phosphoric acid per day.
SYSTEM 1 - PHYSICAL/CHEMICAL PLUS ACTIVATED SLUDGE
System 1 consists of chemical/physical treatment followed by
activated sludge. The early attempts(winter and spring 1976) to develop
an activated sludge culture were not successful. As discussed in connec-
tion with Systems 3 and A, phosphorus limitation and ammonia toxicity
inhibited these efforts. These two difficulties were overcome by the
addition of phosphoric acid as a neutralizing agent for the lime treat-
ment effluent and by the use of air stripping of ammonia. System #1 was
successful only after the implementation of these measures and, as a
result, this discussion is limited to the time period after implementa-
tion.
-39-
-------
The BOD, COD, and ammonia-N data showed a dramatic
improvement in treatment efficiency during August. Approximately
four weeks were needed to develop the activated sludge micro-
organisms to the point where they were capable of rapid growth at the
expense of the leachate substrate. Table 12 shows the results follow-
ing the successful adaptation of the activated sludge. The starting
date for analysis of these data was chosen as August 1, 1976, which
marks the point at which the activated sludge had become fully accli-
mated in terms of ammonia-N, BOD and COD removals.
The results presented in Table 12 demonstrate the high level of
treatment efficiency attainable with System 1- This treatment system
can achieve removals greater than ninety percent for ammonia, BOD, COD,
and iron; and greater than two-thirds for suspended solids, alkalinity,
magnesium, kjeldahl-N, cadmium, lead, mercury, and zinc. Relatively
poor removals of chromium and nickel were achieved with System #1.
Chromium removals have averaged 28.6 percent, and this low efficiency
is attributed to two factors. In the first place, any hexavalent
chromium will not be removed by lime precipitation without previous
oxidation to the trivalent state; and, in the second place, the pre-
cipitation of trivalent chromium at pH 10 is not optimal (See Table 5).
This is because the solubility of chromic hydroxide is at a
minimum at pH 8.5~9.5 and increases with increasing pH. During the
time period represented by Table 12, the clarifier pH was consistently
above 10, and frequently over 11, whereas during the period represented
by Tables 14 and 17 the pH was consistently below 10. Thus, we are
able to see chromium removals as a function of clarifier pH, and this
opens the possibility that the operator can control pH as a method of
differentially affecting effluent heavy metals concentration. The
fairly low removals of nickel may also be related to the relatively
low hydrogen ion concentrations. Based on theoretical considerations
of the solubility of nickel hydroxide, the nickel concentration in the
effluent should be on the order of 0.01 mg/l'°, as opposed to observed
average or 0.27 mg/1. This observation is perhaps also due to the
formation of nickel complexes with unknown chelating agents within
the landfill.
The results observed with phosphates, sulfates and chloride should
be noted. Little removal of chloride takes place because of its rela-
tive biochemical inertness. The concentration of phosphates and sulfates
increase during the course of treatment because of the addition of sul-
furic and phosphoric acids as neutralizing agents. Initially, both
acids were used in excess in order to encourage the growth of the acti-
vated sludge microorganisms. That is, the goal was to provide a very
favorable environment in terms of both pH and the nutrient phosphorus.
However, following the successful acclimation of the activated sludge,
the addition of sulfuric acid has stopped while that of the phosphoric
acid has been drastically cut back. Neutralization is no longer needed
because of the recarbonation effect of aeration in the lagoon. The
present criterion for phosphoric acid addition is to provide just enough
-------
SYSTEM 1* TREATMENT
Table 12
PERFORMANCE AFTER ACCLIMATION
(August 1976)
OF ACTIVATED SLUDGE
Item
Concentration
Percentage Removal
Influent
Effluent
Suspended sol ids
Dissolved sol ids
COD
BOD
Alkal inity
Hardness
Magnesium
Calcium
Chloride
Sulfate
Phosphate
Ammonia-N
Kjeldahl-N
Sod i urn
Potassium ;
Cadmium
Chromium
Copper
1 ron
Nickel
Lead
Zinc
Mercury
1*1*5
10849
9689
4993
3718
4647
495
819
3172
197
1.62
510
539
992
823
0.049
0.105
.313
205
.52
.545
3.64
.015
126
5369
576
60.5
388
1629
109
472
2925
1333
17.8
46.5
141
724
505
0.014
.075
.078
.96
.27
.12
.44
.004
71.7
50.5
94.1
98.8
89.6
64.9
78.0
42.4
7.8
--
--
90.9
73.8
49.1
38.6
71.4
28.6
75.1
99.5
48.1
78.0
87-9
73.3
*This system consists of lime addition, sedimentation, air stripping,
neutralization, nutrient supplementation and activated sludge.
-41-
-------
to satisfy the microorganisms' demand as indicated by ar. effluent con-
centration of about 1 mg/1. That is, the criterion at present is to add.
enough h^PO/t so that there is residual phosphate (1 mg/liter) in the efflu-
ent. This level is one to two orders of magnitude greater than the amount
in the lagoon.
The difficulties in obtaining a healthy culture of activated sludge
have been overcome. The operating experience indicates that "he earlier
problems were in fact due to ammonia toxicity and phosphorus limitation.
The ammonia stripping lagoon has maintained the concentration of this
inhibitor below toxic levels. The mean and standard deviation of the
lagoon effluent ammonia concentration are such that 99 percent of the time,
the feed to the activated sludge unit is less than ^25 mg NH3-N/liter.
The corresponding raw leachate concentration is 1285 mg NHj-N/liter.
Thus, the lagoon has functioned to minimize the shock loading effect of
inhibitory ammonia concentrations. This in turn provided an opportunity
for the development of microorganisms capable of extracting carbonaceous
BOD. As this group became established, organic concentrations in the
mixed liquor were reduced and this created conditions suitable for the
development of nitrifying organisms. Growth of these groups of micro-
organisms has resulted in the low effluent concentrations of both BOD
and ammonia.
As seen in Table 12, a considerable change in alkalinity occurs
during biological treatment. There are two main mechanisms by which
this occurs. First, the aeration causes some removal of gaseous car-
bon dioxide, resulting in a shift of the carbonate equilibria and a
change in total carbonate alkalinity. It is probable, however, that
in this case, nitrification has a more profound effect on alkalinity.
As a result of nitrification, alkalinity is consumed and carbon dioxide
is produced. Neglecting the effect of biomass synthesis, the theoretical
value is 7-1^ rng alkalinity as CaCOj destroyed per mg NH/J+-N oxidized.
In this study, a ratio of 5-6 mg alkalinity per mg NHj,"*"-N removed has
been observed since the development of the activated sludge culture.
This is in excellent agreement with the theoretical value if one con-
siders that the observed value includes the effects of biomass growth
and air stripping in the bio-units as well as shifting chemical equi-
libria in addition to those of nitrification.
Operational Comments
Operating problems have been encountered in the biological treatment
unit, and these are being addressed and solved at this time. The most
serious of these has been a tendency of solids to float in the secondary
clarifier. The result of this is a decreased ability to achieve the
expected level of solids separation. The presence of the floating sludge
has been investigated and is characterized as being the. result of three
separate and distinct causes: flotation, turbulence and denitrifIcation.
It is apparent that there is some carryover of floating materials to the
clarifier from the aeration tank. The leachate contains considerable
-A2-
-------
amounts of surface active materials capable of flotation, and this
contributes significantly to the carryover phenomenon. The scum con-
trol device is not capable of handling the unexpectedly large amount
of these materials. At the same time, an excessive amount of turbu-
lence exists in the secondary clarifier. These first two sources of
the problem are being corrected by the installation of mechanical
skimmers and construction of a baffle on the inlet side of the second-
ary clarifier.
The reduction in solids separation efficiency is compounded by a
propensity of the activated sludge to become anaerobic and to rise in
the clarifier due to denitrification. This is seen clearly when one
follows closely the settleable solids test. At first, the sludge
settles properly with a dense sludge layer overlain by a clear super-
natant containing little turbidity, so that at the end of 30-3** min
the settleable solids are about 300 mg/liter. If the test is continued
for another hour, the sludge comes to the surface in typical rising
sludge fashion. This is not a case of filamentous bulking as indi-
cated by microscopic examination, the clear supernatant observed in the
settleable solids test, and the sludge volume index of approximately
80 mg/g. Another indication of anaerobic denitrification as the cause
of the floating sludge is the repeated observation of very low DO levels
in the clarifier. This problem has been accentuated since a portion of
the plant aeration capacity was diverted to the ammonia-stripping
lagoon, although this is being rectified by bringing another compressor
on-line.
Cost Data
Costs incurred during the operation of the biological units are
indicated in Table 13. The operation and maintenance costs are shown
for the operational period following the initial start-up phase.
The data indicate a cost of $5.12 per thousand gallons treated.
The high power costs reflect the demand for electricity for leachate
pumping, effluent pumping, and maintenance of the laboratory in addi-
tion to the requirements for actual treatment. In the future, it will
be necessary to separate these power costs, in order to more accurately
determine the cost of treatment.^ The labor requirement is approximately
20 man-hours per week.
SYSTEM 2. CHEMICAL/PHYSICAL TREATMENT
This discussion is presented in two parts. The first consists of
the results associated only with lime treatment, and the second includes
the ammonia stripping lagoon. Full-scale data were collected for System
2 without the lagoon during the periods December 11, 1975 to January
12, 1976 and June H, 1976 to August 31, 1976, all dates inclusive. The
results of this phase of the treatment plant operation are summarized in
Table I1*.
-------
Table 13
OPERATION AND MAINTENANCE COSTS INCURRED DURING THE OPERATION
OF SYSTEM 1 FOLLOWING ACCLIMATION OF ACTIVATED SLUDGE
Characteristic
Operational Period
Total Flow, gal
cu m
Lime used, Ib
lb/1000 gal
kg/cu m
Sulfuric acid, gal
gal/1000 gal
1i ter/cu m
Phosphoric acid, gal
gal/1000 gal
1i ter/cu m
309930
1173
29650
95.7
11.5
213
0.687
0.687
26.k
0.0852
0.0852
Costs, S/1000 gal
Powe r
Lime
H2SOi,
Total
t
$1.26
2.87
.57
.21
$5.12
-Mi-
-------
Table 15 presents the changes in each parameter attributable to
the lime treatment. In very approximate terms, the lime precipitation/
clarification sequence, System 2a, removed (see Column 7, Table H)
one-third of the dissolved solids and nitrogen; one-half of the organic
matter, hardness and alkalinity; three-quarters of the suspended solids;
and ninety percent of the phosphates. The removal of heavy metals was
one-third of cadmium, one-half of chromfum and nickel; two-thirds of the
lead and mercury; three-quarters of the copper and over ninety percent
of the iron and zinc. The increase in sulfate is due primarily to con-
taminants in the chemicals, although oxidation of sulfides may contri-
bute somewhat. In other words, this section of the system performed
as expected in pre-treating the leachate prior to biological treatment.
The results of the overall chemical/physical section including the
lagoon (System 2b) are listed in Table 1*» which shows the basic sta-
tistical relationships. Treatment performance in terms of percent
removal efficiency of the lagoon alone and in conjunction with lime
treatment are also seen in Table 1*». The primary goal of the lagoon
was achieved as the concentration of ammonia-N was reduced to 317
mg/liter, a level which was found to be tolerable for purposes of
biological waste treatment. A splash plate, which was installed on
August 9 to promote air/water contact, did not produce an appreciable
effect on lagoon ammonia removals.
Many parameters other than ammonia were altered while in the lagoon.
There was some stabi1ization of organic matter as shown by the reductions
in BOD, COD and dissolved solids. This was mediated by biochemical pro-
cesses and the increase in suspended solids is related to the growth of
microorganisms, as are the reductions in sulfate and phosphate. The re-
duction in alkalinity and pH is most likely due to aeration effects al-
though nitrification reactions may partially contribute to the observa-
tion. The reduction of hardness, calcium and magnesium are related and
may be explained by the formation of calcium/and magnesium carbonates.
In this form, these would not be detected by the usual tests. Most of
the other changes noted in the lagoon effluent vs. lagoon influent com-
parison are due to the limitations of the experimental techniques or to
the radically variable nature of the raw leachate.
The overall treatment efficiency of the complete chemical/physical
section is summarized in Table 1A. These data do not include the
effect of neutralization. The values in the last column (Column \k)
represent removal efficiencies for the lime precipitation/sedimentation/
ammonia stripping sequence. In terms of organic matter, 56.1 and 56.7
percent of the BOD and COD are removed, respectively. Approximately
sixty percent of the ammonia-N and total kjeldahl nitrogen are removed.
The removal of suspended solids, alkalinity and hardness is about two-
thirds. The removal of metals was as follows: 50-65 percent removal
of cadmium, nickel and mercury; 70-80 percent of chromium and copper;
88 percent of lead; 95 percent of z.inc; and 99 percent of iron.
-------
Table |l|
SUMMARY OF SYSTEM 2 RESULTS. EACH SYSTEM CONSISTS OF LIME TREATMENT AND CLARIFICATION.
SYSTEM 2a ant 2b ARE WITHOUT AND WITH AIR STRIPPING OF AMMONIA, RESPECTIVELY."
Parameter
Alkalinity, as CaCOj
Aomonla-N
BOD- 5
Cadmium
Calcium, as CaCOj
Chloride
Chromium
COO
Copper
Dissolved Solids
Hardness, as CaCOj
Iron
Kjeldahl-N
Lead
Magnesium, as CaCOj
Mercury
Nickel
pH
Phosphates
Potassium
Sodium
Sulfate
Suspended Solids
Total Solids
Zinc
System 2a
Influent Effluent
n x cv
(1) (2) (3)
23 5705 0.23
23 1989 1.14
26 5462 0.60
20 0.01)6 J.39
21 709 0.31
19 5577 0.55
21 0.169 0.56
76 11419 0.40
21 0.489 0.8)
93 M533 0.25
21 5460 0.34
21 267 0.65
20 1975 1.33
18 0.53 0.60
21 692 0.50
16 0.011 0.90
21 0.57 0.33
106 7.13
21 2.80 0.63
19 1035 0.26
21 1275 0.24
20 126 0.88
92 1450 0.6s
9 IMS') 0.30
21 9.59 .65
n x cv R
(4) (5) (6) (7)
25 3182 0.26 44.2
26 1245 1.15 37.4
25 2692 0.52 50.7
22 0.03 0.43 34.8
23 645 0.71 9.0
21 4265 0.77 33.5
23 0.090 0.59 46.7
74 5782 .42 49.4
23 0.108 .53 77.9
90 7615 .28 34.0
23 2716 0.57 50.3
23 4.9 3.18 98.2
23 1227 1.39 37.9
20 0.18 0.72 66.0
22 254 0.95 63.9
18 0.0039 1.13 64.5
23 0.28 0.36 50.9
107 9.25
22 0.34 2.12 87.9
21 721 0.26 30.3
23 , 862 0.29 32.4
22 477 1.02
89 403 0.75 72.2
10 6718 .20 39.8
23 0.59 1.58 93.8
System 2b
Influent Effluent
n x cv
(8) (9) (10)
10 5235 0.35
10 763 0.23
12 6001 0.61
10 .044 G.52
10 749 0.39
10 4340 0.36
10 0.138 .62
43 9920 .23
10 .646 .79
44 10324 0.18
10 5115 0.33
10 226 0.77
10 761 0.36
7 0.54 0.89
10 576 0.26
10 .015 0.60
10 .597 0.43
55 7.22
10 2.39 0.66
8 1080 0.19
10 1240 .23
10 110 1.05
44 1240 0.77
9 11154 0.30
10 6.01 0.65
n x cv R
(II) (12) (13) (14)
10 1572 0.15 70.0
12 317 0. II 58.5
12 2632 0.27 56.1
10 .0207 .48 53.0
10 448 0.22 40.2
10 3167 0.12 27.0
10' 0.04 .50 71.0
47 4295 0.13 56.7
10 .098 .82 84.8
45 5428 0.08 47.4
10 1796 .40 64.9
10 2.21 1.14 99.0
II 326 0.12 57.2
7 0.061 .49 88.7
10 163 .82 71.7
10 .007 1.14 53.3
10 .23 .21 61.5
56 8.59
10 0.03 1.33 98.7
8 639 0.09 40.8
10 751 .13 39.4
10 257 0.18
45 430 0.65 65.3
10 5779 0.01 48.2
10 0.276 0.36 95.4
Lagoon
Only
R
(15)
49.5
40.8
23.6
22.2
16.2
-6.2
28.3
19.3
10.3
14.3
13.1
-51.5
39.5
-76.0
7.6
27.0
2.5
65.4
-1.3
-2.9
7-1
-32.8
48.2
I
-e-
"All units are rog/liter except pH which Is express In pH units.
removal. System 2a effluent Is the lagoon Influent.
R stands for percent
-------
Table 15
SUMMARY OF EFFECTS OF CHEMICAL/PHYSICAL TREATMENT"
•
Suspended So) ids
Dissolved Sol ids
Total Solids
COD
BOD
Alkal inity
Hardness
Magnesium
Calcium
Chloride
Sulfate
Phosphate
Ammon i a-N
Kjeldahl-N
Sod i urn
Potassium
Cadmium
Chromium
Copper
Iron
Nickel
Lead
Zinc
Mercury
PH ' ,
Influent
199*
11190
11154
11210
MSB
5685
5116
652
651
4816
114
2.8!
1966
1660
1177
959
.Ok
.16
.44
245
.53
.52
8.70
/ .007
7.06
Lime Treatment
Effluent
403
7615
6718
5782
2692
3182
2716
254
645
4265
477
.3*
1245
1227
862
721
.03
.09
.11
4.9
.28
.18
.59
.004
9-25
Lagoon
Effluent?"
430
5428
5779
4296
2632
1572
1796
163
448
3167
257
.03
317
326
751
639
.021
.04
.10
2.21
.23
.06
.28
.007
8.59
••The influent data are those collected during the entire operational
period, whereas the effluents figures refer to those periods when the
specific units were operating.
+AII units are mg/1 except pH which is expressed in pH units.
-47-
-------
Chian and DeWalle have formed an hypothesis, which is summarized
in Table 6, concerning the treatability of raw leachate. The BOD/COD
ratio observed in the study (Column 2 of Table 14 of the leachate
was 0.48 and the average COD was 11,419 mg/liter. Thus, according to
Chian and DeWalle, the leachate treatment efficiency obtainable with
lime should be poor to fair. In this study (Column 7» Table 14) -the
lime treatment efficiency for BOD and COD has been about fifty percent.
Hence, in terms of the removal of organics, the Chian and DeWalle^" hy-
pothesis is supported. However, it must be mentioned that their hypothe-
sis did not include the removal of heavy metals, and that the lime
treated heavy metal removals have been good to excellent at the faci-
lity.
An additional effect of the ammonia stripping lagoon is the equali-
zing effect which, as noted by LaGrega and Keenan23, can be measured in
terms of both flow variability and quality fluctuations. The presence
of the lagoon has allowed the operator to control the flow leaving the
lagoon by control of the pump settings. This has provided flow equali-
zation to the biological units. The increased uniformity of the nature
of the waste can be seen in Columns 10 and 13 of Table 14 which show
the changes in the coefficient of variation through the chemical/physical
section of the plant. The coefficient of variation is the ratio of the
arithmetic mean to the standard deviation, and as such is a measure of
the dispersion of the data about the mean. The coefficient, which
increases as variability increases, exhibits a general decrease through
the lagoon. This is seen for all parameters except phosphate, cadmium,
chromium, copper, iron, magnesium, hardness and mercury, for which the
data become more variable through the lagoon. This is not entirely un-
expected. The concentrations of some of these parameters are near the
detectable limit, and hence variability may be high. The observation
that several of these are heavy metals has not been satisfactorily ex-
plained.
Operational Comments
The primary operational factor has been the chemicals required
for precipitation and neutralization. A summary of these is presented
in Table 16. The rows labeled, average applied dose, have been cal-
culated by omitting those days on which chemicals could not be added
because of equipment malfunctions.
Cost Data
The cost of materials and electricity is appended to Table
units are given in terms of dollars per one thousand gallons of leachate
treated. The cost has been $2.80-$3-24 per thousand gallons. The power
costs are quite high, reflecting energy consumption not only for chemical
treatment, but also for leachate pumping, air compressors and the labora-
tory. The cost of operation has come down recently as the phosphoric and
sulfuric acid requirements have dropped considerably as experience has
been gained.- Manpower costs for operation and maintenance is approxi-
mately twenty hours per week.
-48-
-------
Table 16
SUMMARY OF OPERATION COSTS DURING EVALUATION OF SYSTEM 2
"
Flow, average gpd
Ipd
total gal
total cu m
Lime, average applied dose,
lb/1000 gal
kg/cu m
total Ib
kg
H2SO/,, average applied dose,
gal/1000 gal
1/cu m
total gal
total liter
HoPO/,, average applied dose,
gal/1000 gal
1/cu m
total gal
total liter
Costs, S/1000 gal .
Powe r
L i me
H2SO|,
H3Pp*
During Operation
Without Lagoon
23,487
88,908
4,227,736
16,002
28.6
3.43
105,455
47,877
0.55
0.55
1,525.1
5,773
.094;
.094'
199.9
757
$1.26
.86
0.45
.23
During Operation
With Lagoon
19,897
75,318
1,571,875
5,950
40.1
4.81
63,050
28,625
.64
.64
978
3,702
.099
.099
152.1
976
$1.26
1.20
0.53
.25
Total
$2.80
$3.24
-49-
-------
SYSTEMS 3 and <4
These treatment sequences were tested In full-scale during the
late winter and early spring of 1976. Severe problems were encountered
in achieving successful treatment. The primary reason underlying these
problems was the inability to develop a healthy activated sludge. Approx-
imately eight weeks were allocated to attempts to adapt a sewage activated
sludge culture to the raw leachate. After this did not succeed, an inves-
tigation revealed that growth of activated sludge was not possible because
of ammonia inhibition and phosphorus limitation. The problems were de-
monstrated by the observations that the average concentrations in the
biological units during this time were 9*»0 mg/liter of ammonia-N and
less than one of phosphorus. The data thus indicated that in the aera-
tion tanks, the ratio of BOD:N:P was 6620:760:1 which is in marked con-
trast to the usual recommendations which are in the range of 90-150:5:1.
The phosphorus limitation was investigated in two ways. First,
replicate BOD tests were set up with varying additions of phosphate
buffer. It was found that the 6005 increased with the phosphorus addi-
tion up to an upper level, indicating that, within this range, phos-
phorus was limiting. As a result of this finding, the BOD procedure
was modified by the addition of sufficient phosphorus to overcome the
1 imitation.
Second, a bench test was initiated to evaluate the hypothesis that
phorus limitation was the reason for the poor development of activated sludge.
The tests consisted of once daily batch draw-and-fi11 experiments in which
the increase in settleable solids was used to monitor the growth of acti-
vated sludge. The control reactor received raw leachate only whereas
the sample reactor received raw leachate plus seven ml of BOD phosphate
buffer per liter of raw leachate. Thus, in the sample reactor, the BOD:
N:P ratip was about 118:13.5:1. The results are summarized in Table 17-
It is se4n that over the short-term, there was an apparent positive im-
pact upon the production of activated sludge and the utilization of COD.
However, when the tests were continued for several weeks, it became ob-
vious that there was no effect of phosphorus addition on either the
development of activated sludge or the removal of organics.
The results of these experiments have been interpreted in the follow-
ing manner. First, the biochemical oxygen demand tests, and the chemical
analyses showed that the leachate was severely phosphorus limited. This
problem became more serious when biological treatment followed lime addi-
tion because of the precipitation of calcium phosphate salts in that
unit. Secondly, the batch draw-and-fi11 experiments showed that alle-
viation of the phosphorus limitation alone is nov enough to encourage
the growth of activated sludge microorganisms.. It was concluded it would
be necessary to reduce ammonia concentrations to a non-inhibitory level
before successful biological treatment could be achieved. Consequently,
the ammonia-stripping lagoon was started up prior to evaluating System 1.
-50-
-------
Table 17
Results of Batch Draw-and-Fi11 Activated Sludge Experiments to Determine
the Extent of Phosphorus Limitation. Results show growth of activated
sludge as ml settleable solids per liter, and COD as mg/liter.
\BOD.N: P
time, days\s.
0
1
2
. 3
4
5 .
6
7
8
9
10 /
1>
12
13
14
15
16
17
18
19
Control
6620:760:1
t
influent effluent
COD COD SS
12813
7704
9339
--
8388 26
12868 10698 20
10193 15
11603
NR
9912
'
5963
9012 7115
13174
, 8606
8221
NR
•
6349
5625
Sample
118:13.5:
influent
COD
12813
7704
9339
—
8388
12868
10193
11603
--
9912
--
5963
9012
13174
8606
8221
6349
—
1
effluent
COD SS
40
7597 40 .
35
71 15
5469
-51-
-------
SYSTEM 5
Although as yet incomplete, studies of the potential of carbon
absorption for leachate treatment have been undertaken. The results
of the evaluation of carbon treatment of raw leachate are presented
here. Any testing of the process as an advanced waste treatment
technique has been postponed until the beginning of the second year.
The preliminary evaluation of this system (System 5 ) has been
carried out for raw leachate treatment. These data are presented in
Table 18. These tests have been performed with an upflow column of
depth 0.3 m and diameter 0.46 m, containing 15.9 kg of granular acti-
vated carbon. The influent flow was 38 liter/min, thus providing a
hydraulic loading rate of 232 l?ter/min/sq m. As shown in Table 18,
no appreciable treatment can be attributed to the carbon treatment.
It should be noted that excessive suspended solids loading and influ-
ent variability contributed to this finding. The effect of the solids
is to cause blockages and hence reduce process efficiency. The influent
was not constant during any of the tests because it was drawn from the
actual plant influent. Therefore it is impossible to calculate re-
moval efficiency. However, it is evident from Table 18 that no renova-
tion is occurring in the carbon columns. Hence, it is concluded that
carbon adsorption is not appropriate when applied to raw leachate,
although, as mentioned above, it may be suitable for final effluent
polishing.
-52-
-------
Tabje 18
r iauin v CAUM uootmot
0 MM
TS • total
M > 6lG«l*c4
T78 • totol volatlta c«Hti«
I ci..-,
(Mil
*
u
01
T»
TW
cn
t tlm
ml
M
OS
n
TW
CM
J IM.
tool
M
M
Tl
TW
CM
» til*.
MUl
«*
a
n
TW
CM
s tim,
MUl
n
M
T»
TW
CM
t tlm.
twl
0*
M
T»
TW
CM
»!• 0
nmi. t>\ 0 •
1.31
two
10170
IJJ50
MM
**SO
0
0
$*>
IOMO
nsao
Si to
SMS
mm 9
«... ml 0 '
too
HIM
nsto
stto
M30
•In 0
flw. ml 0
no
IOMO
tosft
,*»30
/MM
•In 0
»<•>. ml 0
779
IOMO
into
$010
10013
•Id 0
«•». «•! 0
llffl
lOtM
HIM
MM
01)
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so
7.SO
u»
IOHO
11770
MM
3SM
S
SO
MO
10*50
HOW
3S50
mi
10
100
SM
lion
111*0
*S)0
1***
t
M
MO
IMSO
into
J330
I07W
t
10
SM
101)0
I0« JO
*)M
SI 70
t
M
ten
SMO
10*10
(170
S7O
10
IM
I.OS
ISM"
SMO
itno
3*M
TOM
S
M
«»
10*10
nno
»J10
SMO
'3
IJO
Mo
HMO
HSU
SIM
SS1I
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HIM
II 7*0
SMO
S«M
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SM
10070
110)0
*no
ssts
IS
120
I0»
10170
nno
MSfl
ssts
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iso
«.OS
t»7B
I02M
1)110
*l<0
SMO
II
HO
ISO
103)0
IOSM
tin
uto
it
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3*0
107)0
11070
»SM
Sttl
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sew
lOtTO
H20
S8M
U
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SM
10510
111)0
»7)0
m*
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in
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101*0
IIS»
J7W
91*1
10
no
I.D
)OM
10170
13110
*7io
MM
1*
IM
710
I03M
11050
»7«0
«8«
19
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$70
H310
11900
SIM
SI 17
1*
2M
MO
10100
11)700
*too
SMO
to
too
7M
101*0
HIM
M70
101 IS
1*
2M
1110
M30
lOtM
MM
ani
21
ISO
8.11
MO
11)0
HIM
-
17M
17 20
170 too
910 4JO
I03M I07M
1IIJO II 170
5070 *WO
M?» sm
a 21
220 ISO
370 SOO
H*»0 IM70
1IUO H170
SI70 1320
I007S SMI'
30
300
HO
102*0 .
10770
UTO
S«0
it
MO
7M
IIOM
• HTM
son
IOOM
)0 .
JOB
IOM
10130
11170
(IM
UM-
t) t* n n
rs» ya MO 120
100 410 210 20
IO)M 10170 112*0 IIISO
IOMO 10*80 II»JO IIITO
3S70 *ST5 *ISO *210
7S!t JIM 41(1 «M
• t» 31 1* 37
2M 310 JM 170
SM (JO 7M *10
10010 IIOM I0)«0 10970
insio n 710 uno 11*00
M70 *StO 4710 5000
I03t5 IM7S H031 11*1
-53-
-------
Conclusions
1. The GROWS landfill leachate is characterized by high organic strength
and by large day-to-day variations.
2. Considerable experience has been gained in the operation of activated
sludge units on raw leachate and on leachate which has received
chemical/physical treatment. It has been tentatively concluded
that this raw leachate must be pre-treated in order to render it
amenable to activated sludge processing. The results indicate that
the raw leachate inhibits the growth of the activated sludge micro-
organisms. Although the presence of heavy metals and low levels of
phosphorus contribute to this inhibition, it is clear that the ex-
cessive concentrations of ammonia-nitrogen are primarily responsible.
At the conclusion of the current operational mode (Spring 1977), bio-
logical treatment of raw leachate will again be attempted.
3. Although the operation of the chemical/physical units will continue
for some time in order to gain experience under a wider variety of
operating conditions, sufficient data have been collected to provide
an evaluation of this method of treating raw leachate. Lime treat-
ment alone provides removal efficiencies of approximately 50 percent
of the organic matter, 75 percent suspended solids, one-third of
cadmium, and at least 50 percent of the other heavy metals.
I*. The complete chemical/physical treatment sequence consisting of lime
precipitation/sedimentation/air stripping achieved the following
levels of removal efficiency: 56-59 percent of the organic matter,
ammonia-N and total kjeldahl-N; 65 percent of the suspended solids,
and 50 percent or better of the heavy metals.
5. Activated sludge treatment of the effluent from the chemical/physical
. units has been extremely successful. It is apparent that the reduc-
tion in ammonia-N afforded by air stripping lagoon has made conditions
more suitable for the growth of activated sludge microorganisms. The
lagoon provides ammonia removals of approximately 65 percent result-
ing in activated sludge influent concentrations of 210-2^5 mg NH^-N/
liter (99 percent confidence interval). Under this condition, the
activated sludge quickly adapted to the leachate with the result that
effluent 8005 concentrations have been consistently less than 100
mg/liter. Nitrifying organisms have developed and produced a nitrified
effluent with very low concentrations of ammonia.
6. Overall, the treatment sequence consisting of chemical/physical (lime
precipitation, sedimentation, air stripping, and neutralization)
followed by activated sludge has produced an excellent final efflu-
ent with the following characteristics:
-5k-
-------
1. Organic matter has been reduced to 61 mg BODr/liter.
This corresponds to 99 percent removal. The corres-
ponding COD removal efficiency is 3k percent. The
effluent BOD to COD ratio is 0.11.
2. The effluent ammonia concentration is 47 mg/liter,
representing 91 percent removal.
3. Heavy metals are found in the effluent at the follow-
ing levels (percent removals are shown in parentheses):
0.014 mg cadmium/liter (71.4 percent); 0.075 mg chromium/
liter (28.6 percent); 0.078 mg copper/liter (75.1
percent); 0.96 mg iron/liter (99.5 percent); 0.12 mg
lead/liter .(78.0 percent); 0.004 mg mercury/liter
(73-3 percent); 0.27 mg nickel/liter (48.1 percent);
0.44 mg zinc/liter (87.9 percent).
-55-
-------
VI. PROGRESS EVALUATION
The. original work schedule for completion of project is shown in
Figure 6. With only minor alterations, this schedule has been
followed closely. A few changes are suggested in this Chapter. These
changes take the form of shifting emphases in light of what has been
accomplished and learned during the first year of the project. Refer-
ring to Figure 7, one can see the v\ork actually accomplished to date.
This includes at least a preliminary evaluation of each of the systems
to be studied.
Systems 1 and 2, i.e., those with chemical/physical treatment as
the first step, have been evaluated and the results are very encourag-
ing. In fact, the success achieved during the summer of 1976 has been
so promising that we propose to continue operating in this mode for the
next six months. We make this proposal in order to obtain data over a
wider range of realistic operating conditions, especially those of higher
flows and lower temperatures expected during the next half year. These
results will be supplemented with bench testing, which is presently
being initiated. The purpose of the bench-scale experiemental program
is to develop kinetic information which can be applied to full-scale
design of chemical/physical and biological units in the future.
Systems 3 and 4 have received preliminary evaluation in tests
conducted during months four to seven. These treatment sequences are
those in which the activated sludge process receives raw leachate. As
indicated in Chapter V.I, the results indicated that the chemical environ-
ment afforded by the raw leachate was a hostile one which would not
permit the growth of activated sludge microorganisms. It was concluded
from the data that ammonia toxicity was responsible for inhibiting the
activated sludge. However, low ambient temperatures may have contri-
buted to these findings. Consequently, during the Spring of 1977, Systems
3 and 4 will be reevaluated. I
During the coming months, it is proposed that increased emphasis
be placed on bench-scale testing including System 5- As mentioned
above, this information will be used to develop kinetic and design cri-
teria and to optimize operational parameters. The bulk of this work will
be focused on System 1 because the data collected indicate that treat-
ment effluent criteria can be readily reached with chemical/physical
treatment followed by activated sludge.
The changes in the emphasis of the experimental program outlined
in the above paragraphs are reflected in Figure 8. In this chart,
it is seen that bench-scale studies and operation of Systems 1 and 2
will continue for the next six months, and fhat Systems 3 and k will
be reevaluated during months eighteen through twenty-three.
-56-
-------
It is jpporent that there is sufficient technical justification for
extension of the project period for a third year. Overall, the purpose
of the demonstration project is to show in a full-size plant that ch^mi- •
cal-physic.il-biological treatment of leachate is possible, to select the
best treatment sequence, and to develop sound treatment cost data.
The various operational sequences of treatment have been put through
their initial tertir.g and it appears that chemical-physical followed by
biological offers the best potential. However, because of the initial
startup period, we should take another look at the other alternatives.
Further, we have come to recognize that leachate quantity and quality
transients are having a significant impact on the plant operation and,
consequently, on the treatment cost data. GROWS has indicated that
they would consider installation of an initial equalization lagoon Lo
permit a more uniform input of leachate. Whether or not they would
authorize such a lagoon depends substantively on the decision with re-
gard tb a third year.
Based on our operating experience to date, there are several factors
which we believe should be evaluated in a third year. The results of .1
third study year would greatly enhance the quality of the final results
of the demonstration project. These factors are briefly outlined below.
1. By construction of the equalization lagoon, flow and quality
characteristics would be smoothened, thereby developing a quasi-
steady state treatment process. This effect would allow for a
better definition of the relationship between treatment cost
and leachate quality. The third year may be used to separate
the total power costs into the component parts: raw leachate
pumping, aerators, other treatment requirements and final
effluent pumping.
2. An extended evaluation of leachate treatment using the proce.ss
sequence scheme which has the most potential will clearly
indicate impact on treatment cost of changes in quantity,
quality and seasons.
3. Some bench scale studies have been performed during the first
two project years; a third year would allow for a full-sized
plant assessment of the pilot plant results.
k. A third year would permit the time necessary to optimize plant
operation, using the selected scheme, by developing techniques
to maximize removal and minimize operating costs.
5. A third year would allow for gathering of additional informa-
tion to refine design criteria.
6. A third year would allow for a full scale investigation of the
potential for operating the plant to maximize the removal of
-57-
-------
specific contaminants, such as particular heavy metals, and to
minimize operating costs. (i.e.., pH adjustment based on metals
present).
-58-
-------
Plant Startup and
Laboratory Installation
Bench Scale Tests
System 1
S v stem 2
final r
/n't. Report
Figure 6
WORK SCHEDULE FOR COMPLETION
OF PROJECT
Dec.
1975
1
1
0
Sept.
1975
1 1
2 A
Jan.
T976
I ,...-.
1 i i 1 I
6 8 10 12 l'<
1 I — 1
1 1 1 1 |
16 18 ?0 22 2*4
Jan.
1977
TIME IN MONTHS
Sy.fcr.i 1 - Chemical-Phys leal followed by Biological
r>y, u-m .2. - Chemical-Physical
System 3 - Biological followed by Chemical-Physical
System ^ - Biological
System 5 - Carbon Adsorption
-------
Figure 7. WORK ACCOMPLISHED DURING FIRST YEAR OF PROJECT
o
i
Plant Startup and
Laboratory Installation
Bench-scale Tests
System 1
System 2
System 3
System A
System 5
Interim Reports
•
Annual Report
0
Sept.
1975
2
If
Jan.
1976
6
8
.
10
12 11
Sept.
1976
!» 16.
Jan.
1977
18
20
22
2k
TIME IN MONTHS
-------
Figure 8. PROPOSED WORK FOR SECOND YEAR OF PROJECT
Plant Startup and
Laboratory Installation
Bench-scale Tests
System 1
System 2
System 3
System ^
System 5.
Annual Report
i
7* Final Report
0 2 k 6 8 10 12 1*4 16 18 20 22 2<4
Sept. Jan. Jan.
1975 1976 1977
—- TIME'IN MONTHS
-------
VII, REFERENCES
1. Remson, I., A.A. Fungaroli and A.W. Lawrence. "Water Movement in an
Unsaturated Sanitary Landfill." Proceedings ASCE, Journal of
the S^ani t.iry Cnginc"ring Division, 9*>, SA2 (1968).
2. Calvert, C. "Contamination of Ground Water by Impounded Garbage
Water". Journal of the American Water Works Association 2*t,
3. Carpenter, L.V. and L.R. Setter. "Some Notes on Sanitary Landfills".
American Journal of Public Health 30, (19^0).
k. University of Southern California. Factors Controlling Utilization
o£ San? tary Landf i 11 Si tes. Final Report .to Pep :rtment of_
Health, Education and Wei fare, Nat ional Inst i tute of Health.
U.S. Public Health Service, Washington, D.C. (1963)7
5. Longwell, Jr. "The Water Pollution Aspect of Refuse Disposal."
Paper No. 6261. Institution of Civil Engineers Proceedings 8,
421-2*4 (1957) .
6. Ministry of Housing and Local Government. Pollution of Water by
Tipped Refuse. Her Majesty: Stationery Office, London (19~6l) •
7. Qasim, S.R. Chemical Characteristics of Seepage Water from Simula-
ted Landfills. Ph.D. Dissertation. West Virginia University,
Morgantown. (1965).
8. Andersen, R.J. and J.N. Dornbush. Influence of Sanitary Landfill on
. Ground Water Quality. Journal American Water Works Association
59, ^ (1967).
9. Hughes, G.M., R.A. Landon and R.N. Farvolden. Summa/ry of the Find-
* ings on Sol id Waste Disposal Si tes in Northeastern 111inois.
Illinois State Geological Survey, Urbana (197U-
10. Steiner, R.L. Chemical and Hydraulic Characteristics of Milled
Refuse. pH.D. Thesis. Drexel University, Philadelphia (1973).
11. Weaver, L. "Refuse Disposal, Its Significance". RATSEC Technical
Report W-6I-S. In Ground Water Contamination. Proceedings
of a 1961 Symposium, pp. 10^-10. Robert A. Taft Sanitary
Engineering Center, Cincinnati (1961).
12. Engineering Science, Inc. Final Report. ln-citu Investigation of
Gases Produced from Decomposing Refuse. Publication No. 35.
State Water Quality Control Board. 'Sacramento, Cal. .(1967).
13. Walker, W.H. "Illinois Ground Water Pollution". Journal American
Water Works Associat ion (19&9 J •
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1^. Roessler, B. "Beeinflussing des Grundwasser durch Mull und
Schuttablayerungen". \, ,m Wasser 18, *3 (1950-50-
15- Lang, A. "Pollution of Water Supplies, Especially Underground
Streams". Gesundh Technical Sladtehyg 2k. (1932).
16. Chian, E.S.K. and F.B. DeWalle. "Sanitary Landfill Leachates
and their Treatment". Proceedings ASCE, Journal of the
Environmental Engineering Di\ is ion 102, EE2, *11-31 (1976) .
17- R. J. Schoenberger, A. A. Fungaroli, R. L. Steiner and S. Zison.
Treatabllity of Leachate from Sanitary Landfills. Mid-Atlantic
Industrial Waste Conference, University of Delaware, Newark
(1971).
18. J. W. Patterson and R.A. Minear. Wastewater Treatment Technology.
Prepared for Illinois Institute of Environmental Quality.
279 PP. Published by NTIS, Springfield, Va. PB-20* 521.
(197D.
19- American Public Health Association, American Water Works Associa-
tion and Water Pollution Control Federation. Sta n da rd Method s
for the Examination of Water and Wastewater. Hth Edition.
Published by APHA, New York (1976).
20. American Society for Testing and Materials. Standards. Part 23
(1972).
21. U. S. Environmental Protection Agency. Manual of Methods for Chem-
ical Analysis of Water and Wastes, 2nd Edition. EPA-625/6-7*-
003 (197*).
22. Analytical Procedures for Chemical Pollutants, Pollution of Sub-
surface Water by Sanitary Landfills". Research grant EP-000162,
NTIS, Springfield, Virginia.
23. LaGrega, M.O. and J.D. Keenan. "Equalization of Sewage Flows".
Journal Water Pollution Control Federation (197*).
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APPENDIX
LEACHATE TREATMENT PLANT OPERATION
AND MAINTENANCE ROUTINE
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Although the profession has considerable experience in the
operation of chemical/physical and biological treatment processes,
there is no literature relative to the operation of leachate treat-
ment plants. It is for this reason that the following section has
been prepared. It is hoped that this information will prove valuable
in the operation of the leachate treatment plants that are sure to
f o 11 ow.
CHEMICAL/PHYSICAL UNITS
Lime Treatment
The lime handling equipment receives routine operator attention
for the fallowing: twice daily backwash of lime pumps and three times
daily'addition of lime to the hopper. The lime slurry lines are
checked daily where they enter the clarifier to ensure the free ilow
of lime slurry. Lime is received about twice per week in shipments of
two pallets which are unloaded and the sacks stored. Maintenance of
the lime pumps is carried out at weekly intervals. This consists of
removing all lines from the pump, draining them and looking for blockage.
The piping is backwashed for about five minutes, and any lime which
has settle^ out in the lime slurry bin i.s broken up and dispersed.
Additional maintenance for the lime system is performed routinely
at monthly intervals. The lime slurry bin is drained completely using
the barrel transfer pump. This has to be done three or more times to
remove most of the material. Any additional residue is scooped out.
Hardened lime .is chipped and scraped away from the sides, pipes, and
mixer blade. 'Both lime pufnps are disconnected, all pipes to the lime
bin are removed, cleaned and backwashed. Ordinarily, some pipes are
replaced and new fittings are often needed. Lime is chipped out of
the pump impellers which have a tendency to work loose, and therefore
need tightening. Lime slurry pipes from the pumps to the clarifier
generally need to be replaced every month due to lime coating resulting
in excessive hydraulic resistance. The float valve in the lime slurry
bin must be completely cleaned and lubricated, and it must be replaced
frequently.
Clarifier
The clarifier in the chemical/physical section has been relatively
maintenance-free. On a routine basis at monthly intervals, it is
necessary to remove excess sludge. This is done by drawing down the
clarifier about 2,000 gal. in order to bring the level below the bottom
of the center rings. The rings are washed out, and the thick hardened
material is chipped away from the mixer blade. The clarifier screw
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gear box and the clarifier mixer are checked monthly for oil. At weekly
intervals, the one fitting on the clarifier mixer and three on the
clarifier drive are greased. Generally, 500 gal of primary clarifier
sludge are wasted daily. Sludge is either pumped d'rectly into a tank
truck or into the sludge holding tank. In the latter case., it is sub-
sequently air lifted or pumped to the tank truck. The truck is filled
and the sludge returned to the landfill approximately two or three
times per week. Tnis includes any sludge wasted from the biological
uni ts.
Lagoon
The flow from the lagoon to the biological unit is checked daily
and is usually adjusted because of influent flow changes. The level
in the lagoon increases radically the day after a heavy rain. Varia-
tions in the flow rate to the biological unit are made on the basis of
maintaining the flow as constant as possible without permitting the
lagoon to empty or overflow.
Acidificat ion
Acid solutions are prepared on an as needed basis. The general
procedure is to add sulfuric acid to a half tank of water by pumping
from the acid barrel with a transfer pump using a one inch hose. At
the present time, the sulfuric acid is added only as needed. The phos-
phoric acid solution is prepared by the addition of two gallons to a
tank of water, and this lasts for two days. The acid pump is checked
and oiled monthly. The check valves are usually replaced at this time.
The acid tank is drained with the barrel transfer pump and any sediment
is swept out. The tubing and back pressure valve are also inspected.
BIOLOGICAL UNITS
Aeration Tanks /
The froth spray nozzles are observed daily and cleaned as necessary.
It is necessary to check .the return sludge line and the scum line. These
air lifts are very sensitive to variations in the air pressure, and they
are usually off if the blower has previously shut down. The blowers are
checked periodically and, at monthly intervals, they are greased and
oiled, and the condition of the belts is noted.
Secondary Clarifier
The surface of the clarifier is cleaned as needed. This is
usually at weekly intervals. The floating material concentrates between
the weirs and the effluent baffles from which it must be removed before
it builds up,overflows the weir and degrades the effluent. Sludge from
the biological unit is wasted as it becomes necessary.
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DATA COLLECTION
Each day at noon, the operator ta''es meter readings of electricity
consumed, volume of effluent treated and volume of influent pumped from
each manhole. The calibration of these readings is occasionally re-
checked as discrepancies have been noted. Samples are collected for
the daily tests: chemical oxygen demand, dissolved solids, suspended
solids, pH, settleable solids, total solids, volatile suspended solids,
dissolved oxygen and temperature. These 'Samples are collected from the
raw leachate, clarifier effluent, lagoon, mixed liquor and final efflu-
ent. Weekly samples are obtained from the same set of sampling points,
and aretanalyzed, in addition to the daily tests, for the following: 5
day biochemical oxygen demand, sulfate, ortho-phosphate, chloride, alka-
linity, ammonia nitrogen, organic nitrogen, kjeldah! nitrogen, hardness,
sodium, potassium, magnesium, calcium, and the heavy metals cadmium,
chromium, copper, iron, lead, mercury, nickel, and zinc. The atomic
absorption spectrometer is used for the heavy metals, and it must be
dismantled and cleaned after each use. ' .
GENERAL MAINTENANCE
This includes general cleaning of the laboratory, plant and grounds,
repair of leaks, etc. There are other pumps not mentioned above which
need grease and oil on a routine schedule. These pumps are for sodium
hydroxide and chlorine, and for the final effluent. In addition, tho
various equipment in the laboratory must be properly maintained.
ya!541
SW-91d
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