United States
Environmental Protection
Agency
Office of Research and
Development
Washington DC 20460
EPA/600/2-86/073
December 1985
&EPA
Critical Review and
Summary of Leachate and
Gas Production from
Landfills
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EPA/600/2-86/073
December 1985
CRITICAL REVIEW AND SUMMARY OF LEACHATE
AND GAS PRODUCTION FROM LANDFILLS
by
Frederick G. Pohland and Stephen R. Harper
School of Civil Engineering
Georgia Institute of Technology
Atlanta, Georgia 30332
U.S. EPA Cooperative Agreement CR809997
Georgia Tech Project No. E-20-G01
Project Officer
Stephen C. James
Land Pollution Control Division
Hazardous Waste Environmental Research Laboratory
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
Printed on Recycled Paper
U.S. Environmental Protection Agency
Region 5, Library (PL-12J)
77 West Jackson Boulevard, 12th Floor
Chicago, IL 60604-3590
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DISCLAIMER
The information in this document has been funded wholly or in part by
the United States Environmental Protection Agency under Cooperative Agreement
CR-809997 to Georgia Institute of Technology. It has been subject to the
Agency's peer and administrative review and has been approved for publication.
The contents reflect the views and policies of the Agency. Mention of trade
names or commercial products does not constitute endorsement or recommendation
for use.
11
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FOREWORD
The Environmental Protection Agency was created because of increasing
public and governmental concern about the nation's environment and its effect
on the health and welfare of the American people. The complexity of the
environment and the interplay among its components require a concentrated and
integrated attack upon environmental problems.
The first step in seeking environmental solution is research and
development to define the problem, measure its impact and project possible
remedies. Research and development is carried out continually by both
industry and governmental agencies concerned with improving the environment.
Much key research and development is conducted by EPA's Hazardous Waste
Engineering Research Laboratory. The laboratory develops new and improved
technologies and systems to treat, store and dispose hazardous waste; to
remove hazardous waste; to remove hazardous waste and restore contaminated
sites to usefulness; and, to promote waste reduction and recycling. . This
publication is one of the products of that research — a vital communications
link between the research and the user community.
This document presents a critical review and summary of available
information and literature on leachate and gas production and management
during the disposal of solid wastes.
Thomas Mauser, Director
Hazardous Waste Engineering Research Laboratory
ill
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ABSTRACT
The purpose of this project was to provide a review and critique of
literature and the status of technology pertaining to the formation, character-
ization and treatment of municipal solid waste (MSW) landfill gas and leachate.
This objective was accommodated by an initial recognition of the various
factors influencing the applicability and efficacy of various landfill
disposal options and/or leachate and gas management strategies. Therefore,
the review is organized to reflect bench-, pilot- and full-scale evaluations;
leachates have been categorized according to low, medium and high strengths;
and product gases have been differentiated on the basis of constituents and
medium or high energy content.
Commencing with a brief historical perspective focusing on the problems
associated with migration of MSW leachate and gas from landfill disposal
sites, the review proceeds with a characterization of MSW gas and leachate
quality produced throughout the phases of landfill stabilization and the
various leachate and gas treatment methods. Accordingly, leachate treatment
by external aerobic and anaerobic biological methods and by _in situ anaerobic
degradation with leachate management are compared to physical-chemical
leachate treatment by chemical oxidation, precipitation, coagulation,
disinfection, absorption, ion exchange and reverse osmosis. In addition,
methods of landfill gas collection and treatment by sorption, refrigeration,
and membrane separation are presented together with the implications of
ultimate disposal of treated leachates, including an understanding of
leachate/soil interactions.
Biological treatment is shown to be superior to physical-chemical methods
for raw leachate; aerobic and anaerobic treatment methods were generally
capable of removing 85 to 99 percent of leachate BOD^ and COD as well as most
heavy metals. The physical-chemical processes are shown to be better suited
for polishing of biological treatment effluents and for the removal of
refractory organics. Leachate management through recycle is also demonstrated
to possess a high potential for process stability, although further effort is
needed to determine application criteria on a large scale. Process loadings,
operational constraints, and degree of variance and uncertainty in reported
data and their interpretation are presented to indicate that past efforts have
not resolved all the technical challenges associated with gas and leachate
management at landfill disposal sites, and that additional investigations are
required.
IV
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CONTENTS
Foreword ill
Abstract iv
Figures viii
Tables xi
Acknowledgment xv
1 . Introduction 1
2. Conclusions 2
General 2
Leachate treatment process performance 2
Gas treatment performance 6
3. Recommendations 7
General 7
In situ treatment of leachates 8
External treatment of leachates and gas 8
Directions for future research 9
4. Landfill Hazards - Historical Perspective 11
Early reports on leachate migration and effects 11
Early reports on gas migration and effects 12
5. Leachate and Gas Production at Sanitary Landfills 14
General perspective 14
Climatic and hydrogeologic factors 14
Input waste characteristics 15
Landfill age (degree of stabilization) 17
Landfill stabilization phases 17
Phase I: Initial adjustment 18
Phase II: Transition 18
Phase III: Acid formation 19
Phase IV: Methane fermentation 19
Phase V: Final maturation 19
Indicator parameters descriptive of
stabilization phases 20
6. Treatment of Leachates from Sanitary Landfills 26
General perspective • 26
Aerobic biological treatment of landfill leachate 26
Bench-scale aerobic treatment studies 27
Activated sludge 27
Aerated lagoon 43
Fixed-film processes 47
Kinetic parameters for bench-scale aerobic
processes 48
Pilot- and full-scale aerobic treatment 48
Activated sludge 48
Aerated lagoon 53
v
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Stabilization pond 53
Treatment and disposal of aerobic process sludges 53
Anaerobic biological processes 59
Bench-scale anaerobic processes 59
Effect of mean cell residence time (8) 59
Organic loading effects 63
Temperature effects 68
Metals removals 68
Anaerobic treatment kinetic parameters 70
Anaerobic process sludge characteristics 70
In situ anaerobic leachate recycle treatment 72
Pilot-scale leachate recycle 72
Full-scale leachate recycle 76
Physical/chemical treatment of leachates 78
Bench-scale physical/chemical leachate treatment
processes 78
Coagulation and precipitation 78
Chemical oxidation 83
Chemical disinfection 84
Chemical process sludge characteristics 84
Ionizing radiation 87
Ion exchange 87
Adsorption 88
Metals removal 90
Reverse osmosis 91
Full-Scale Physical/Chemical Leachate Treatment 93
Precipitation/coagulation 93
Ammonia stripping 96
Activated carbon adsorption 96
Final leachate disposal 97
Land disposal 97
Discharge to POTW 98
Surface water discharge 98
7. Gas Management 99
General perspective 99
Gas production 99
Factors affecting landfill gas production 100
Nature of refuse placed 100
Moisture content 1 00
Particle size and degree of refuse compaction 101
Buffer capacity 101
Nutrients 101
Temperature 101
Gas Extraction 102
Gas Yield Projections 102
Theoretical Models 102
Empirical gas yield projections 104
Gas production rate predictions 104
Gas composition 106
Collection and treatment of landfill gases 111
Landfill gas collection 111
Landfill gas treatment 113
Economics 115
8. Leachate and Soil Interactions 117
General perspective 117
VI
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Heavy metal attenuation 118
Pesticide migration 119
Organics 120
Other toxic compounds 121
Analytical modeling of leachate/soil interactions 122
References 1 23
Appendices 1 47
Vll
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FIGURES
Number Page
Treatment Options Available for Leachate and Gas
Management and Ultimate Disposal
2 Solutions to the Management of Leachate and Gas
from Landfill Disposal of Solid Wastes .................... 10
3 Changes in Selected Indicator Parameters During
the Phases of Landfill Stabilization ...................... 25
4 Relationship Between 6C and BOD^ Removal for
Bench-Scale Activated Sludge Studies ...................... 30
5 Relationship Between 9C and COD for Bench-Scale
Activated Sludge Studies .................................. 32
6 Comparison of 6C vs. COD Removal Data Segregated
According to Biodegradability Ratios BOD/COD and
COD/TOC [[[ 33
7 Relationship Between Organic Loading Rate and
Removal for Bench-Scale Activated Sludge Studies .......... 34
8 Relationship Between Organic Loading Rate and COD
Removal for Bench-Scale Activated Sludge Studies .......... 35
9 Relationship of Organic Loading Rate vs. COD Removal
for Data Segregated by Biodegradability Ratios ............ 36
10 Relationship Between Food to Microorganism Ratio (F/M)
and BODc; Removal for Bench-Scale Activated Sludge
Studies [[[ 38
11 Relationship Between F/M Ratio and COD Removal for
Bench-Scale Activated Sludge Studies ...................... 39
12 Relationship Between Temperature and COD Removal for
Bench-Scale Activated Sludge Studies ...................... 40
13 Relationship Between 9C and Nitrification for
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15
16
17
19
20
21
22
23
25
26
27
28
Relationship Between Leachate/Domestic Wastewater
Volume Ratio and Organics (BOD5, COD) Removal for
Bench- and Pilot-Scale Combined Wastewater
Activated Sludge|Studies
Relationship
Organics Removal
Studies
Between Hydraulic Retention Time (T) and
for Bench-Scale Aerated Lagoon
Between
Relationship
Removal for Bench
Relationship
Residence Times
Sludges
Between
Sludge Volume Index and Mean Cell
'or Aerobic Biological Treatment
Between
Relationship
Removal for Benclk
Between
Relationship
Removal for BenclJi
Illustration of (tOD Removal vs. 9C for Anaerobic
Treatment Data Segregated According to Biodegradability
Ratios
Relationship Between
Removal for Bench
Relationship Between
Removal for Bench
Processes
Relationship Between
COD Loading Rates
Treatment Studies
Relationship Betv
for Bench-Scale
Relationship Betv
by Bench-Scale
Relationships
Chemical Coagular
Relationships Between
Chemical Precipitants
Removals
Relationship
COD Removal for
Studies
Between
Organic Loading Rate and Organics
-Scale Aerated Lagoon Studies
Mean Cell Residence Time and
-Scale Anaerobic Treatment Studies
Mean Cell Residence Time and COD
-Scale Anaerobic Treatment Studies...
Organic Loading Rate and
-Scale Anaerobic Treatment Studies.
Organic Loading Rate and COD
-Scale Anaerobic Treatment
Gas Production and
for Bench-Scale Anaerobic
and
reen Temperature and Organics Removal
naerobic Treatment of Leachate
reen Temperature and Gas Production
Anaerobic Treatment of Leachate
Between
pH and Dosages of Various
ts and Corresponding COD Removals.
pH and Dosages of Various
and Corresponding COD
Chemical Oxidant Dosage and
Bench-Scale Chemical Oxidation
44
45
46
58
61
62
64
65
66
67
69
69
82
82
83
IX
-------
29 Comparison of the Organic Removal Efficiencies and
Sludge Volumes Produced by the Application of
Various Chemical Dosages to the Treatment of
Leachates on Bench-Scale 86
30 Freundlich Isotherm Curves for Bench-Scale Batch
Activated Carbon Treatment of Raw, Biologically or
Chemically Treated Leachates 89
x
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TABLES
Number Page
1 Summary of Leachate Treatment Process Capabilities ....... 4
2 Waste Source Categories and Corresponding Waste
Types ................. . ................................... 15
3 Range of Composition of Municipal Solid Waste ............. 16
4 Landfill Leachate and Gas Constituent Concentration
Ranges Encountered in the Literature and Their
Relative Significance to the Degree of Landfill
Stabilization ............................................. 21
5 Bench-Scale Research on Aerobic Leachate Treatment
Processes ................................................. 28
6 Leachate Organic Strength Categories ...................... 27
7 Summary of Heavy Metal and Alkali and Alkaline Earth
Metal Removal Data for the Bench-Scale Activated
Sludge Process ............................................ 41
8 Bench-Scale Research Performed on Combined Treatment
of Leachate and Domestic Wastewater Using the
Activated Sludge Process .................................. 42
9 Experimental Conditions and Performance During
Trickling Filter and Rotating Biological Contractor
Treatment of Leachate ..................................... 47
10 Summary of Monod Kinetic Parameters for Activated
Sludge Treatment of Leachate .............................. 49
11 Landfills with Pilot- or Full-Scale Aerobic Leachate
Treatment Facilities ...................................... 50
12 Summary of Leachate Treatment Performance and Design
Parameters for Pilot-Scale and Full-Scale Activated
Sludge Treatment Facilities ............................... 51
13 Summary of Leachate Treatment Performance and Design
Parameters for Full-Scale Aerated Lagoon Facilities ....... 54
XI
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1 ** Summary of Leachate Treatment Performance and Design
Parameters for Full-Scale Stabilization Pond
Facilities 55
15 Summary of Sludge Characteristics for Aerobic Leachate
Treatment Processes 57
16 Bench-Scale Anaerobic Biological Treatment of
Leachate 60
17 Summary of Heavy Metal and Alkali and Alkaline
Earth Metal Removal Data for Bench-Scale Anaerobic
Treatment Processes 68
18 Summary of Monod Kinetic Parameters for the
Anaerobic Leachate Treatment Process 70
19 Summary of Sludge Characteristics for the Anaerobic
Leachate Treatment Process 71
20 Pilot-Scale Research Performed on Leachate Treatment
by Leachate Recycle 73
21 Summary of Test Variables, Leachate Character, and
Gas Results for the Pilot-Scale Leachate Recycle
Studies 75
22 Summary of Available Information Concerning the
Application of Leachate Recycle at Full-Scale
Landfills in Germany 77
23 Organic Characteristics of Leachates Removed from a
Full-Scale Two Stage Recirculation Process in
Germany 78
24 Bench-Scale Research Performed on Leachate Treatment
by Physical/Chemical Processes 79
25 Summary of Heavy Metal and Alkali and Alkaline Earth
Metal Removal Data for Bench-Scale Chemical Addition
Processes 81
26 Bench-Scale Research Performed with Chemical
Disinfection of Leachate 85
27 Summary of Ion Exchange Performance Using Effluents
from Aerated Lagoon and Activated Sludge Leachate
Treatment Systems 87
28 Summary of Glauconitic Greensand (GG) Performance for
the Removal of Metals from Leachate 88
XII
-------
29 Summary of Freundlich Isotherm Parameters for
Bench-Scale Activated Carbon Adsorption of Raw
Leachate and Treated Leachate 88
30 Summary of the Performance of Peat for Adsorption
of Organics and Metals from Leachate 90
31 Summary of Heavy Metal and Alkali and Alkaline Earth
Metal Removal Data with Activated Carbon Adsorption
and Resin Ion Exchange Treatment of Leachate 91
32 Summary of Reverse Osmosis Performance for the Removal
of COD from Raw and Biologically Treated Landfill
Leachates 92
33 Full-Scale Leachate Treatment Facilities Using a
Physical/Chemical Process 93
34 Summary of Performance and Design Parameters for
Full-Scale Physical/Chemical Leachate Treatment
Facilities 94
35 Effluent Disposal Practices Employed by Full-Scale
Leachate Treatment Facilities 97
36 Examples of Municipal.Solid Waste Chemical Formulas
Applied to Theoretical Methane Yield Models 103
37 Summary of Theoretical Gas Yields from Municipal Solid
Waste Reported in the Literature 103
38 Summary of Experimental Observations of Gas Production
from Municipal Solid Waste 105
39 Summary of Experimental Observations of Gas Production
Rates in Small-Scale Landfill Simulators 106
40 On-Line Landfill Gas Recovery Facilities in U.S 107
41 Summary of Landfill Gas Composition at Full-Scale
Landfills 108
42 Trace Constituents Detected in Landfill Gases 108
43 Representative List of Organic Compounds Identified
in Landfill Gas 109
44 Summary of Average VOC Concentrations and Threshold
Limit Values 110
45 Advantages and Disadvantages of Gas Collection Piping
Materials 112
Xlll
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46 Summary of Gas Treatment Methods Available for the
Removal of Water, Hydrocarbons, C02, and H2S
Relative Economics of Several Gas Treatment
Alternatives .............................................. 116
xiv
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ACKNOWLEDGMENT
The authors acknowledge the collaborative efforts of Mr. Joseph Dertien
(leachate treatment), and the able assistance of Mr. Bijoy Ghosh (gas
management) and Dr. Robert C. Bachus (soil interactions) in the acquisition
and evaluation of the materials for this report. The typing efforts of
Ms. Henrietta Bowman and Ms. Elaine Sharpe are also acknowledged together with
the complementary support provided by the School of Civil Engineering at the
Georgia Institute of Technology.
XV
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SECTION 1
INTRODUCTION
Sanitary landfills continue to be the most frequently employed method of
solid waste disposal practiced in the United States. Unfortunately, sanitary
landfills remain poorly understood and loosely managed; deficiencies magnified
and manifested by usual inadequacies in waste definition and understanding of
associated environmental variables. During the last decade, the potential for
production of leachate and gas has received major attention particularly in
terms of environmental consequences associated with the migration of leachate
and gas during conversion of waste constituents. These concerns have led to a
variety of developments for control, including the concepts of leachate
containment and total landfill isolation. In accordance with these
strategies, various techniques have been proposed and implemented for the
treatment and disposal of landfill gases and leachates.
The purpose of this report is to provide a review and summary of the
nature of leachate and gas production at landfills, and to couple this
with a concomitant inventory of available techniques for containment, control
and treatment. The review begins with a brief historical perspective of
hazards associated with the migration of leachate and gas from landfill
disposal sites. Factors affecting the quantity and quality of landfill
leachate and gas are then addressed, followed by processes used or advocated
for leachate and gas treatment. Hence, investigations into activated sludge,
aerated lagoons, trickling filters, biodisks, anaerobic contact processes and
in situ leachate recycle technologies as well as coagulation, precipitation,
chemical oxidation, disinfection, adsorption, ion exchange, and reverse
osmosis processes in either separate or combined configurations are detailed.
Finally, methods for the ultimate disposal of leachate and gas are addressed,
including discharge to municipal wastewater treatment plants, land
application, and energy recovery.
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SECTION 2
CONCLUSIONS
GENERAL
The development of rational and economically sound solutions to landfill
leachate and gas migration hazards encompasses the analysis of several major
factors. As shown in Figure 1, a given landfill in its natural setting will
affect and be affected by numerous hydrologic and geologic circumstances that
must be properly recognized and managed to minimize human and environmental
risks. In particular, leachate and gases formed as a consequence of external
moisture inputs and waste degradation may migrate into the surrounding
environment, contaminate drinking water supplies and create other
environmental hazards.
The first step towards effective management of gas and leachates at
susceptible landfill sites logically begins with containment by installation
of "impermeable" barriers augmented by drainage, venting, and collection
systems sufficient to handle the inevitable production of leachate and gas.
Following their generation and capture, leachate and gas must be treated and
disposed of in an environmentally acceptable and economically sound manner.
As also shown in Figure 1, there are a number of options available for
leachate and gas management prior to ultimate disposal. Before being
discharged onto land or into a publicly owned treatment works (POTW),
landfill leachate and gas will require treatment by biological and/or
physical-chemical methods. Some of these methods have been proven successful,
while others have been shown to have limited applicability. Moreover, it is
widely recognized that the quantity and quality of landfill leachate and gas
are influenced by numerous variables which have resulted in a diversity of
relative treatment efficiences when similar processes have been applied.
However, some generalizations on the advantages and disadvantages of these
processes have become evident, as are outlined in the remainder of this
section.
LEACHATE TREATMENT PROCESS PERFORMANCE
When considering separate treatment of raw leachate for removal of
biodegradable fractions, biological treatment systems were significantly
superior to physical-chemical techniques. As indicated in the performance
summary presented in Table 1, if given sufficient residence time, biological
processes typically achieved 90 to 99$ organics (6005 and COD) removal and
yielded effluents having COD concentrations less than 500 mg/1. The aerobic
treatment processes were generally capable of 90% NHg-N conversion and
typically yielded effluents containing less than 10 mg/1 N^-N for 9C >10 days.
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DIRECT USE
PIPELINE
FLARING
DRINKING WATER
CONTAMINATION
MUNICIPAL:
i AND :
INDUSTRIAL
WASTE
POTENTIAL
FIRE HAZARDS
EACHATE
RECYCLE
EXTERNAL TREATMENT
BIOLOGICAL TREATMENT
ANAEROBIC FILTER
ANAEROBIC CONTACT
ACTIVATED SLUDGE
AERATED LAGOON
STABILIZATION POND
FIXED-FILM PROCESSES
COMBINED TREATMENT
PHYSICAL/CHEMICAL TREATMENT
PRECIPITATION/COAGULATION
CHEMICAL OXIDATION
DISINFECTION
ADSORPTION
ION EXCHANGE
REVERSE OSMOSIS
P.O.T.W.
DISCHARGE OPTIONS s LAND APPLICATION
Figure 1. Treatment Options Available for Leachate and
Gas Management and Ultimate Disposal
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TABLE I. SUMMARY OF LEACHATE TREATMENT PROCESS CAPABILITIES
BODc; COD TKN Fe Zn
AEROBIC BIOLOGICAL
PROCESSES
Activated Sludge
Combined Leachate
and Sewage
Aerated Lagoon
Stabilization Pond
Aerobic Fixed Film*
ANAEROBIC BIOLOGICAL
PROCESSES
Attached Growth
Suspended Growth
Leachate Recycle
PHYSICAL/CHEMICAL
PROCESSES
Coagulation
Oxidation
Reverse Osmosis
Ion Exchange
Adsorption
Rem., Effl., Rem.,
* mg/1 »
95 100 95
91-99 3-15 92-98
99 5-60 92-98
93-99 10-100 99
85-98 100-900 75-95
85-98 100-900 75-95
NA <100 NA
12
10-50
86-91
10-70
75-99
Effl., Rem.,
mg/1 %
500 70-95
25-60
300-800 10-70*
100-100 70-99
200-1000
200-1000
<5 NA
100-10,000 —
1000-8000 —
<10
100-300
Effl. , Rem. ,
mg/1 J
10-100 96-99
10-80 99
1-100 80-99
80-99
80-99
20-1000 NA
95-99
99
10-80
65-95
Effl., Rem., Effl.,
mg/1 % mg/1
10-10 96-99 3-10
0.2
1-100
5-25 80-99 0.5-10
5-25 80-99 0.5-10
5-50 NA 0.2-1
2-17 75-98 <1
<1 90 <1
1-10 20-96 <1
2-15
Ni
Rem., Effl., Comments
J mg/1
60 0.25 80 - 6-10 days
ratio <5%
8C >10 days
T >10 days
10-80 0.1-1 80 >10 days
10-80 0.1-1 80 >5 days
NA — 60 >500 days
Lime, alum,
ferric chloride
Ozone, chloride
permanganate
Raw Leachate
Pretreated Leachate
11-96 <1 Commercial IX
Resins and GG
GAC and PAC
Rem. = Removal; Effl. - Effluent
'insufficient data to make an adequate judgment; **TOC Basis
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For 6C of 6 to 10 days, the limiting range for aerobic carbonaceous material
conversion, 60 to £>Q% nitrification was generally also achieved.
Like the aerobic biological processes, anaerobic biological processes
have been successfully applied for treatment of raw leachates. COD and 6005
removals of 90% were typically achieved at residence times longer than 10 days.
With these conditions, gas production from anaerobic processes ranged from 0.4
to 0.6 m3/kg COD destroyed or 0.8 to 0.9 m3/kg BODg destroyed.
Aerobic biological processes were fairly efficiently applied for removal
of heavy metals. Zinc, iron, cadmium and manganese were removed best,
followed by lower removals of chromium, lead and nickel. Zinc, chromium, and
iron were removed at efficiencies greater than 90% during anaerobic treatment;
copper, lead, cadmium, and nickel removals were on the order of 50 to 90%.
Removals of alkaline earth metals were relatively unaffected in both aerobic
and anaerobic processes, although the activated sludge process has been
reported to remove 64 to 99$ calcium.
With the exception of activated carbon, the physical-chemical processes
were generally unsuccessfully applied for removal of organic materials from
raw leachates. However, reverse osmosis, activated carbon (GAG and PAC) and
ion exhange (IX) were successfully applied to treated effluents from
biological treatment processes. Reverse osmosis treatment removed a high
percentage of organics from both raw and treated leachates, although fouling
problems limited its applicability to raw leachates. Ion exchange treatment
was generally ineffective for organics removal, although cation exchange
resins such as glauconitic greensand (GC) were successful in removing copper,
lead and nickel (these were poorly removed in biological processes). Iron and
zinc were also relatively well removed, as were chromium, manganese, calcium
and magnesium.
Activated carbon adsorption was shown to be capable of removing the
majority of residual organics from chemical and biological leachate treatment
process effluents, yielding 8005 concentrations after adsorption of less than
50 mg/1. Raw leachates have also been treated using activated carbon,
achieving >95% TOC removal «100 mg/1 effluent) with a maximum adsorptive
capacity of 200 mg TOC/g AC.
In situ treatment of leachate using leachate containment and recycle back
through the landfill mass has been demonstrated to be successful on pilot- and
full-scale. Effluents from leachate recycle studies were typically 30 to 350
mg/1 BOD5, 70 to 500 mg/1 COD, 4 to 40 mg/1 iron and <1 mg/1 zinc. The
implementation of leachate recycle also generally reduced the time required
for biological stabilization of the readily biologically degradable leachate
constituents by as much as an order of magnitude. Whereas, wastes in
landfills without leachate recirculation may require 15 to 20 years to
stabilize, leachate recycle may shorten this period to 2 to 3 years.
Moreover, if removal and ultimate disposal of accumulated leachate are
followed by appropriate capping and maintenance of closed landfill sections,
the potential for long-term adverse environmental impacts will be greatly
diminished by concomitant removal of refractory substances remaining in the
stabilized leachate and also depriving the system of that liquid (leachate)
transport medium. Therefore, although the ultimate reactivity or fate of
refractory compounds within landfills have not been well established, leachate
recycle appears to offer a management option that can help reduce this degree
of uncertainty and provide a better basis for predicting ultimate behavior.
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GAS TREATMENT PROCESS PERFORMANCE
Effective recovery of energy (methane) from landfills requires
appropriate provisions for gas collection and treatment, preferably conceived
prior to the initiation of landfill operations. These systems need to be
sized according to expected gas rates and yields. Based upon experiences
recorded in the literature, from 0.005 to 0.10 m3 of total gas have been
produced per kilogram of dry refuse placed. Most of the total gas is produced
over a relatively short period during the "life" of a landfill; the majority
of methane will be produced within a few years after the onset of rapid
stabilization and methanogenesis. Accordingly, typical gas production rates
reported in the literature have ranged from 0.001 to 0.008 nwkg of dry
refuse/year. With recycle augmented stabilization, these rates may be
increased due to the shortened period (months versus years) for accelerated
conversion of the readily available biodegradable materials present in the
refuse and leachate. The associated gas composition has ranged from M5 to 60%
methane with the balance being primarily carbon dioxide with smaller amounts
of hydrogen, oxygen, nitrogen and traces of other gases.
The choice of treatment technologies utilized for purifying recovered
landfill gas has depended on the intended use of the product. For high BTU
pipeline quality gas, treatment has traditionally included the removal of
water, carbon dioxide, hydrogen sulfide, hydrocarbons and, on occasion,
nitrogen. For on-site use applications, lesser degrees of treatment have
commonly been required, including the removal of water and hydrogen sulfide,
but not necessarily carbon dioxide, hydrocarbons and nitrogen.
Water removal may be best effected by adsorption or absorption;
absorption with ethylene glycol at <20°F «6.7°C) appears to be the method of
choice. Non-methane hydrocarbons may be removed using carbon adsorption.
Carbon dioxide may be removed by organic solvents, alkaline salt solutions, or
alkanolamines which seem to be the most popular. Hydrogen sulfide may be
removed along with C02 by the above methods, or selectively removed by
particular absorbents or adsorbents. Many of the solvent processes exhibit a
higher affinity for H2S than for C02, therefore, these gases may be removed
concurrently in most cases. Dry oxidation processes (such as iron sponges)
are more specific for hydrogen sulfide, although the non-regenerative nature
of the support materials (such as wood shavings) often poses a requirement for
additonal recharging procedures. Nitrogen may be removed by liquefying the
methane fraction of landfill gas, although this is energy intensive which
underscores the need to avoid introducing air during extraction from the
landfill.
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SECTION 3
RECOMMENDATIONS
GENERAL
The generation and treatment of landfill and leachate gas are influenced
by many factors, many of which are poorly understood and ineffectively
controlled or managed. Moreover, it is likely that the current practice of
codisposal of small quantities of toxic and hazardous industrial wastes with
municipal refuse will present increasing management challenges as leachates
and gases are generated. Collectively, these issues have been emphasized by
the results of studies reviewed herein with respect to the variations in
quantity and quality of leachates and gases produced in time and space within
a given landfill setting. Associated uncertainties tend to stymie management
efforts and, as a result, the design, construction and operation of external
leachate treatment facilities have not been standardized. Likewise, efforts
directed toward energy (methane) recovery have been limited because of the
difficulties in predicting variations in gas quality and production, as well
as securing justification for such an initiative within the user community.
To help alleviate such problems during design and operation of leachate
and gas management systems, it is desirable to have as much control over the
generation of leachate and gas as possible and to thereby transfer the process
from the realm of uncertainty to that of predictability. This can only be
accomplished if control over leachate constituents is exercised either through
the pre-selection of waste source ingredients or by management of their rate
of generation and transfer to the transport medium (leachate or gas). The
latter approach appears to be a more logical choice in the case of municipal
landfills; the former, perhaps coupled with the latter, would seem more
attractive for industrial landfills.
Based upon an understanding of the processes effecting leachate character-
istics, management of generation and transfer rates can be implemented by
management of the moisture regime within the landfill. Without moisture, the
transport medium will not exist and the conversions and interactions
determining leachate (and gas) quality will be suppressed. Once under
control, the availability of moisture can be used to advantage to accelerate
processes producing leachable constituents, to carry the constituents from the
waste mass, to dilute out inhibitory ingredients and/or refractory compounds,
to add seed, nutrients or buffer capacity to augment biological activity, and
to transport residuals for ultimate treatment or disposal.
Implicit in this management concept are requirements for containment and
ultimate disposal. Current technology provides a sufficiency of techniques
for containment with natural or fabricated liners which have become generally
-------
accepted. Ultimate disposal relates to the sensitivity of the eventual
environmental receptor, whether it be the land or the water. However, under
prevailing regulatory constraints and state-of-the-art technology, both
require some degree of leachate pretreatment before ultimate disposal is
acceptable. It is the premise here that such pretreatment can be best
provided in engineered systems that have the resiliency to cope with changing
leachate characteristics.
In situ Treatment of Leachates
For on-site applications, it is recommended that leachate recycle be
recognized as affording the flexibility needed to successfully manage landfill
leachates, both with respect to leachate quality and quantity and energy
recovery. Associated design of leachate and gas collection and distribution
systems should be standardized and coupled with management plans allowing
sequenced operation of the landfill and reuse of appurtenances to minimize
overall costs and maximize the benefits of such treatment. Current evidence
suggesting lower costs of leachate recycle in contained sites as compared to
either separate aerobic or anaerobic treatment systems should be confirmed.
In addition, since with leachate recycle the landfill itself provides the
treatment system, operational contingencies should be established in relation
to the accelerated production of leachate constituents and their eventual
conversion to gas.
Whether leachate values are attractive for recovery and/or reuse also
relates to the type of treatment provided. At many conventional municipal
landfills, gross uncertainties persist throughout operation and after closure
of the site. Accordingly, gas and leachate production events are generally
unpredictable and neither gas nor leachate may be efficiently recovered for
controlled discharge. With leachate recycle and its inherent ability to
accelerate waste and leachate conversion with concomitant methane production,
gas collection and possible utilization becomes more viable and such an option
should be investigated further, particularly on full-scale. Moreover, the
degree of stabilization of the waste mass as compared to conventional landfill
practice needs to be established with regard to residual leachate character
and decisions on ultimate leachate disposal including foreclosure and
postclosure requirements.
External Treatment of Leachates and Gas
In the case of external treatment of leachates, the most logical first
step appears to be biological treatment. Stabilization ponds or aerated
lagoons can be most cost effective if land area is readily available; if not,
anaerobic treatment or aerobic activated sludge processes may be used. The
choice between anaerobic and aerobic processes for leachate treatment is a
difficult one, although the retention times needed in either case are similar.
Therefore, the energy surplus associated with methane production and aerator
elimination may favor anaerobic processes. Both processes require further
site specific testing on pilot- and full-scale to determine these issues. In
particular, these systems will require attention to the flexibility in design
and operation necessary to meet the challenges imposed by the stochastic
nature of leachates (and gas) in both quality and quantity.
-------
Following external biological treatment (or _in situ treatment, as above),
the effluents will still contain significant organic and inorganic residual
concentrations. Therefore, polishing treatment prior to disposal on land or
into a POTW such as by activated carbon adsorption, ion exchange or reverse
osmosis needs to be included in the overall study approach. Precipitation and
coagulation processes should also be considered where justified. In all
cases, gas management or recovery need to be an integral part of any
investigative initiative.
Directions for Future Research
Based upon the observations gained from this review, the present
state-of-the-art in landfill leachate and gas management appears to be
comprised of the elements represented in Figure 2. From this figure, it is
suggested that 90 to 95% of the organics and metals leached from landfill
waste may be removed by biological processes such as leachate recycle or
external aerobic and anaerobic treatment systems. However, the capabilities
of these processes are not fully established; further study is needed in each
area to develop meaningful economic and realistic process control comparisons
of these alternatives. Evaluations of leachate treatment and the gas
production possible from the use of leachate recycle on full-scale are
particularly needed, as well as parallel evaluations of both aerobic and
anaerobic fixed-film processes on pilot- and full-scale, respectively. The
sequence approach to leachate recycle on full-scale needs development to
establish the economic incentives associated with minimizing leachate
distribution and gas collection appurtenances and maximizing gas/recovery
utilization. In all biological treatment cases, the stochastic nature of
leachate and gas production in both quantity and quality needs to be merged
with design and operational procedures.
Activated carbon, ion exchange or reverse osmosis polishing of effluents
from biological treatment processes need further confirmation on full-scale.
Included in these analyses should be a characterization of organics and
inorganics escaping treatment, and the potential for improving final polishing
by chemical pretreatment or post-treatment. Coupled with this initiative
should be more detailed analyses of the character and fate of the priority
pollutants appearing throughout the various phases of landfill stabilization
and/or in situ or separate treatment.
Finally, the present knowledge of chemical and physical processes
involved in management of gas and leachate from landfills is not sufficiently
detailed to support development of a unified approach to leachate and gas
treatment and possible resource recovery. Although much is known about
factors that influence composition and volume of leachate and gas from
landfills, this information is quantitative only for well 'controlled systems
that are operated at laboratory or pilot scale. Many of the processes are not
fully understood and information from field-scale systems remains qualitative
and highly variable. Consequently, it is recommended that research and/or
demonstration studies should be directed toward improving quantitative
knowledge of the fundamental processes operative in field-scale systems and
integrating this information into a strategy for standardized management and
control of all types of landfills.
-------
MEDIUM-BTU (DIRECT USE)
HIQH-BTU (PIPELINE)
REMOVAL
CO, . H,3
> * =£> 2 =
REMOVAL REMOVAL
REMOVAL " REMOVAL
Gas Treatment
1
AND; INDUStftfAi WASTE
COMBINED
TREATMENT
(Leachate
Laachate/Wast
+ Sewage)
w«lor ratio < 5%
IN SITl
vs.
EXTERNAL
FREATMEN]
Leachate
Recycle
90-98 % Organic
and Metal removal
AEROBIC or ANAEROBIC
Biological
Treatment
90-98 % Organic
and Metal removal
)N E
DSO II TIOM
>A
OXIDATION
T
Physical-
Chemical
Treatment
98-99 % Organic
and Metal removal
Discharge
LAND APPLICATION
i
to P.O.T.W.
Figure 2. Solutions to the Management of Leachate
and Gas from Landfill Disposal of Solid
Wastes
10
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SECTION 4
LANDFILL HAZARDS - HISTORICAL PERSPECTIVE
The technical literature has frequently documented problems associated
with leachate and gas production from landfills, generally in terms of
migration into the adjacent environment. Although often difficult to
quantify, much of the earlier recorded information is instructive to the
extent that it established a relatively early recognition and emphasis on
these environmental problems. Therefore, a brief discussion of this early
work is provided as an introduction to the more current investigations.
EARLY REPORTS ON LEACHATE MIGRATION AND EFFECTS
Potential problems associated with the burial of solid and liquid wastes
have been documented as early as 1932 by Calvert (1932) who reported increased
levels of hardness, calcium, magnesium, total solids, and carbon dioxide in a
well more than 150 m from an impounding pit. Similarly, Carpenter and Setter
(1940) sampled the water from the bottom of a refuse fill and reported
contaminant concentrations of 1987 mg/1 6005, 3867 mg/1 alkalinity as CaC03,
and 3506 mg/1 chloride. Lang (1941) reported the pollution of a well which
was more than 600 m from a fill site. In a study on leaching of land-disposed
wastes, Merz (1964) determined that if fill materials are allowed to contact
groundwater either intermittently or continuously, the water becomes so
grossly polluted to preclude its domestic or irrigation use.
Based on a study of an existing landfill located in an abandoned gravel
pit, Anderson and Dornbush (1967) reported that groundwater in the immediate
vicinity of the landfill, as well as that in direct contact with the landfill,
exhibited an increase in ionic strength. Water quality impairment by excess
ions decreased with distance from the landfill area. In studies on the
characteristics of refuse tips in England, it was concluded that leaching
could promote the growth of bacterial slimes and/or fungus in groundwater
systems and lead to taste and odor problems (Davison, 1969). In California,
groundwater below the Riverside Landfill contained markedly increased
concentrations of BOD, chloride, sodium, and sulfate; increases of these
contaminants over background were 26, 10, 9, and 8 times, respectively (Coe,
1970). Pollution of a surface water supply in Kansas City, MO was attributed
to leaching of organic compounds from an industrial waste landfill into the
Missouri River one mile (1.6 km) above the city's water intake (Hopkins and
Poplisky, 1970). In 1975, the U.S. Environmental Protection Agency (EPA)
assessed leachate damages from five municipal waste disposal sites reported by
Fungaroli (1971) where contamination of groundwater and pollution of
residential, industrial or public water supply wells occurred. The necessity
to abandon all wells resulted in a costly replacement of the water supply.
11
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Shuster (1976a) reported on the improper management of a landfill which
resulted in serious contamination of public water supplies., Initially
operated as an open dump, the City of Aurora, IL contracted in 1965 to have a
private company operate the landfill at a site located over a creviced bedrock
aquifer. Within two months of filling an excavated trench (dug to bedrock)
with commerical, industrial, and septic tank wastes, seven residential wells
were contaminated with leachate and declared totally unusable. BOD levels in
three of the wells greatly exceeded levels reported for raw sewage. Shuster
(1976b) similarly reported on a landfill site in Rockford, IL which was
formerly a sand and gravel pit. Prior to placing the wastes into the site,
sand was removed from a 161,880-m2 (40-acre) area to a depth of 9.1 to 12.2 m
(30-40 ft) below grade; the location of the water table was at 10.4 m (34
feet) below grade. As a result, four residential wells, four industrial wells
and one public water supply well were contaminated. All wells were
subsequently abandoned and alternative water supplies were established.
A 1977 Report to Congress presented data which documented contamination
from various municipal and industrial land disposal sites (EPA, 1977). A
total of 42 municipal and 18 industrial disposal sites were surveyed, and five
of the municipal and 14 of the industrial sites were shown to contribute toxic
pollutants to the local water supply. In all cases, groundwater contamination
was the most common type of environmental damage.
EARLY REPORTS ON GAS MIGRATION AND EFFECTS
Landfill gases may also migrate from a landfill site and pose problems
ranging from malodors and corrosion to fire or explosions. Methane migration
and accumulation into subsurface structures, including sewerage system
manholes and catch basins and into commercial and residential basements may
explode if the methane is diluted with air to 5 to 15$. Zabetakis (1962)
reported on the presence of methane at 2.1J in malodorous gases collected near
water pipes at a number of homes built over a previous dump site. MacFarland
(1970) summarized a report of a recreation center explosion in Atlanta, GA
where two workmen were killed and two others seriously injured. As in the
case of the homes, the recreation center had been rebuilt virtually on top of
decomposing refuse. The explosion, which completely destroyed the recreation
building, was attributed to methane orginating from the buried wastes.
Flammable gas concentrations were found in nearly all probes placed within a
44.4-m (200-ft) radius of the demolished structure.
More recently, a British group (County Surveyors Society, Committee No.
4; 1982) surveyed 51 governmental agencies to determine the extent knowledge
concerning landfill gas hazards. Of the agencies queried, 27 reported
problems associated with fires and explosions. No deaths were reported
associated with landfill explosion hazards, although two children were
asphyxiated in a culvert extending from under a landfill in 1977. Injuries to
children playing with matches or fireworks near manholes or drainage culverts
were reported in several counties, and hazards to electrical, phone, and
maintenance workers, including several large explosions, were also recorded.
Numerous other incidents involving explosions and fires (62 total incidents)
in which no personal injury was involved were also reported. Fires were
apparently common both above and below ground, particularly in manholes.
12
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In response to these problems, the control of landfill gas and leachate
has received considerable attention and is often mandated by permit
requirements. The current technology for gas control and treatment ranges
from controlled ventilation to capture and processing for energy recovery.
The planning and technological requirements associated with these approaches
are addressed in more detail under the GAS MANAGEMENT section of this report.
Similarly, the current technology for leachate management encompasses a
variety of treatment or disposal options which are detailed in the LEACHATE
TREATMENT section of this report.
13
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SECTION 5
LEACHATE AND GAS PRODUCTION AT SANITARY LANDFILLS
GENERAL PERSPECTIVE
The chemical characterization of leachates and gases emanating from
landfill operations is a first and necessary step toward a meaningful analysis
of potential environmental impacts and the consideration of containment,
control and treatment strategies. Unfortunately, the nature of landfill
leachates (and gases to a lesser'extent) varies widely in response to
differences in climatic and hydrogeologic influences, the nature of the wastes
contained at each site, and the age of the landfill (or its degree of
stabilization). It is the purpose of this section to introduce and review the
implications of these variables and to formulate an overall perspective and
general characterization of landfill leachates and product gases.
CLIMATIC AND HYDROGEOLOGIC FACTORS
Rainfall provides the transport phase for leaching and migration of
contaminants from a landfill and the moisture needed for biological activity
leading to methane production. Although some moisture may be derived from the
input wastes, the major precursor to leachate formation is infiltration from
rainfall. The contact opportunity of this infiltration can be affected by
certain landfill management options, including the cover configuration,
liners, and the landfilling technique employed. In addition, the natural and
imposed hydrogeologic conditions play a major role in determining the nature
and fate of leachates and gases at sanitary landfills. Unfortunately, much
uncertainty remains in this regard and analytical techniques often fail to
reveal discontinuties in geologic and hydrologic dimensions.
Under similar infiltration constraints, the impact of climate on leachate
quantity and quality is fairly well understood. In hot and humid climates,
leachate production could be maximum compared to that generated in hot and
arid climates. High levels of rainfall and porous soils create large
quantities of'leachates, although the concentrations of contaminants leached
will be lower than in low rainfall areas. Evapotranspiration may also play a
significant role in the overall water balance, particularly in hot and arid
regions.
Although the hydrogeologic environments of any two landfills will have
certain conceptual similarities, each landfill will exhibit factors unique to
its setting which will greatly influence the nature and fate of leachates
formed. Therefore, a three dimensional understanding of infiltration and
groundwater movement is necessary for evaluating the suitability of candidate
landfill sites or for planning control strategies at existing landfills.
14
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Important factors include particle sizes and types of soils in the underlying
strata, soil or other material used as a daily cover, and sizes and degree of
compaction of wastes placed (Hughes, _e_t _al., 1971). Obviously, finely
textured materials will allow for relatively low rates of leachate or gas
movement, whereas, coarse materials or fractured bedrock will allow relatively
easy passage of both liquids and gases.
These site specific uncertainties have been the primary contributors to
deviations in leachate and gas characteristics from seemingly similar wastes.
Moreover, they have often promoted an insistence on the application of
restrictive management concepts, ranging from leachate removal and treatment
to total landfill containment or waste encapsulation. Reliable and convincing
hydrogeologic mapping will be increasingly required to offset growing concerns
about short- and long-term impacts of landfills intended for the receipt of
wastes from the industrial or municipal sectors. (This subject will be
further addressed under the LEACHATE AND SOIL INTERACTIONS section of this
report.)
INPUT WASTE CHARACTERISTICS
The majority of wastes disposed of in sanitary landfills are solid in
nature, although the presence of municipal and industrial sludges is also
common. Wastes originating from different source categories will contain
different constituents which will also impart certain associated
characteristics to the leachate produced.
As shown in Table 2, five major source categories can be identified;
residential, agricultural, commercial, municipal, and industrial.
Accordingly, residential and commercial wastes are comprised primarily of
paper products (rubbish) ash, and food wastes. Agricultural wastes will
include these products plus larger proportions of organic materials from crops
and animals (agricultural wastes may also contain some potentially toxic
material in the form of insecticides or pesticides). Industrial wastes will
contain materials characteristic of the industry from which they originate.
TABLE 2. WASTE SOURCE CATEGORIES AND
CORRESPONDING WASTE TYPES
Source Category Major Waste Constituents
Residential Rubbish, food and garden wastes, plastics, glass, ash
Agricultural Crop and animal wastes, food wastes, rubbish, chemicals
Commercial Rubbish, food wastes, construction/demolition debris, ash
Municipal Rubbish, ash, food wastes, sewage sludge
Industrial Biological and chemical sludges, rubbish, ash,
construction/demolition debris
15
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Several investigators have determined the relative composition of
municipal solid wastes. As summarized in Table 3» the diversity of the
results presented is indicative of the high potential for variance in the
composition and relative proportions of wastes contributed from each source
category. Nevertheless, from these analyses it can be expected that rubbish,
food and garden wastes, and crop and animal residues will contribute organic
compounds. Organic compounds will also be available from sewage sludges and
certain industrial wastes. These wastes will also contribute to the moisture
needed for leachate formation and biological activity leading to gas
production. Ash wastes will contribute inorganic constituents, as will
construction and demolition debris and the many types of industrial sludges
and residues which constitute common sources of heavy metals.
TABLE 3. RANGE OF COMPOSITION OF MUNICIPAL SOLID WASTE
Reference Source
Component
Food Wastes
Garden Wastes
Paper
Cardboard
Plastics
Rubber
Leather
Textiles
Plastic Film
Wood
Glass
Metallics
Tin Cans
Non-ferrous Metals
Ferrous Metals
Dirt, Ashes,
Brick, etc.
Moisture
(149) (116) (175) (36)
Average Average Average Range Average
12 >25.1 25.0 8.8-12.8 10.7
0 5.8-17.0 10.4
39 44.5 50.0 >35.2-45.3 >40.6
7
>22 >3.0 >4.2-5.2 >4.6
2
3 1.1 5.0 1.1-2.5 1.7
2
7 1.0 0.4-1.3 1.0
10 11.3 7.0 9.1-12.4 10.9
8 8.7 4.0 8.0-8.6 9.0
10 7.1 5.0 1.0-3.6 2.8
(78) (259)
Range Average Range Ty
4-9 7 6-26
1-10 5 0-20
45-57 50 25-45
3-15
2-8
4-9 6 0-2
0-2
2-5 3 0-4
1-2 1 1-4
9-17 12 4-16
6-15 10
2-8
0-1
1-4
3-15 7 0-10
21-35 27 15-40
pical
15
12
40
4
3
1
1
2
2
8
6
1
2
4
20
Percent by weight, wet weight basis
The codisposal of industrial sludges and residues with municipal,
commercial, agricultural and/or residential wastes provides a potential source
of toxic constituents. These constituents are usually inorganic (alkali and
alkaline earth metals, heavy metals, nitrogen and sulfur compounds) but may
also be organic in nature. Therefore, their migration into groundwater may
pose health hazards and may actually inhibit or impede landfill stabilization
or the performance of external leachate treatment processes. Nevertheless,
16
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due to the small generator exclusion in the Resource Conservation and Recovery
Act (RCRA), small quantities of hazardous materials have been and are
currently being codisposed in sanitary landfills and need to be considered as
a recognized input. In these cases, in situ stabilization may occur at
reduced rates as the leachate becomes more concentrated, and the extended
stabilization period increases the opportunity for leachate migration from the
landfill.
The degree of inhibition of the biologically mediated processes of
stabilization within a landfill will depend upon the nature and quantities of
potential inhibitors present. Recent research has demonstrated that
appropriate combinations of industrial wastes with municipal refuse can reduce
and/or eliminate the otherwise adverse effects of industrial wastes on
stabilization (Bromley and Wilson, 1981; Jones and Malone, 1982; Chang, 1982).
In some cases, codisposal of industrial wastes may contribute moisture or
buffer capacity which encourages the onset of biological stabilization within
the landfill (Kinman, ert al_. , 1980; Kinman, 1982). Swartzbaugh, et al.,
(1978) reported that codisposal of several industrial wastes generally
increased overall moisture content and caused a more rapid attainment of field
capacity. However, experiments with petroleum wastes revealed a potential for
the inhibition of leachate formation, and codisposal of battery wastes
resulted in higher concentrations of leachate metals and other inorganic
contaminants.
The differences in impact attributed to the industrial waste component
during codisposal may also be a function of pH. Using small-scale leaching
tests, Houle (1977) noted increased mobilization of metallic ions when
leachate was used instead of distilled water. Similarly, Streng (1976) noted
increased metal mobility during tests of codisposal of six selected industrial
wastes. In contrast, Barber, e^ aJ., (1981) indicated that larger-scale
studies revealed little evidence of increased metal leaching except at below
pH 5. The authors speculated that this was due to attenuation by bicarbonate
and sulfide precipitates and complexes. Similar observations have been
recorded by Pohland, et_ al_., (1981) and Walsh, et_ a^., (1983), i.e., leaching
of metals was initially attenuated by sulfide precipitation, followed by an
increased mobility in the latter phases of biological stabilization due to
possible complexation.
LANDFILL AGE (DEGREE OF STABILIZATION)
Landfill Stabilization Phases
The coupling of landfill age with leachate and gas production (quantity
and quality) has been one of the seemingly most elusive challenges confronting
designers, operators, and regulators of landfill disposal sites. The designer
may conceive of operational features not responsive to requirements for
leachate management as leachate is produced and changes in quality with time.
Similarly, the treatment plant operator may be frustrated by the inability to
adjust to these emerging circumstances, and the regulator may impose highly
conservative and/or restrictive conditions in anticipation of these events,
thereby stifling development and implementation of new and innovative
technology.
17
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In reality, most landfills receiving municipal solid waste proceed
through a series of rather predictable events whose significance and longevity
are largely determined by the previously mentioned climatological conditions,
operational variables, management options, and control factors operative or
being applied either external or internal to the landfill environment.
Fortunately these events can be followed by certain leachate (and gas)
analyses, selecting those parameters as major environmental factors that best
describe certain conditions or "phases" of stabilization.
To direct the choice of analyses to be used to describe a particular
phase of stabilization, it is necessary to recognize that a landfill exists
throughout much of its active life as an anaerobic microbial process,
analogous in concept to a batch digester, with limited inputs or outputs
except for the refuse and moisture or eventual gas production and possible
leachate migration, respectively. Using this analogy and recognizing that the
functional retention time extends over a period of years rather than days,
certain performance related and time dependent concepts emerge.
As with many anaerobic digestion systems, landfills experience an initial
lag or adjustment phase which lasts until sufficient moisture has accumulated
to encourage the development of a viable microbial community, the evidence of
which is first observed in leachate quality when "field capacity" has been
reached. Thereafter, further manifestations of waste conversion and
stabilization may be reflected by changes in leachate and gas quality as
stabilization proceeds through several more or less discrete and sequential
phases, each varying in intensity and longevity according to prevailing
.operational circumstances. To illustrate this premise, the following five
stabilization phases have been identified in terms of the principal events
occurring during each (Pohland, e_t al_., 1983).
Phase I: Initial Adjustment—
Initial waste placement and preliminary moisture accumulates.
Initial subsidence and closure of each landfill area.
Changes in environmental parameters are first detected to reflect the
onset of stabilization processes which are trending in a logical
fashion.
Phase II: Transition—
• Field capacity is exceeded and leachate is formed.
A transition from initial aerobic to anaerobic microbial stabilization
occurs.
The primary electron acceptor shifts from oxygen to nitrates and
sulfates with the displacement of oxygen by carbon dioxide in the gas.
• A trend toward reducing conditions is established.
• Measurable intermediates such as the volatile organic fatty acids
first appear in the leachate.
18
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Phase III: Acid Formation—
Intermediary volatile organic fatty acids become predominant with the
continuing hydrolysis and fermentation of waste and leachate
constituents.
A precipitous decrease in pH occurs with a concomitant mobilization
and possible complexation of metal species.
Nutrients such as nitrogen and phosphorus are released and utilized in
support of the growth of biomass commensurate with the prevailing
substrate conversion rates.
Hydrogen may be detected and affect the nature and type of
intermediary products being formed.
Phase IV: Methane Fermentation—
Intermediary products appearing during the acid formation phase are
converted to methane and excess carbon dioxide.
The pH returns from a buffer level controlled by the volatile organic
fatty acids to one characteristic of the bicarbonate buffering system.
Oxidation-reduction potentials are at their lowest values.
Nutrients continue to be consumed.
Complexation and precipitation of metal species proceed.
Leachate organic strength is dramatically decreased in correspondence
with increases in gas production.
Phase V: Final Maturation—
Relative dormancy following active biological stabilization of the
readily available organic constituents in the waste and leachate.
Nutrients may become limiting.
• Measurable gas production all but ceases.
Natural environmental conditions become reinstated.
Oxygen and oxidized species may slowly reappear with a corresponding
increase in oxidation-reduction potential.
• More microbially resistant organic materials may be slowly converted
with the possible production of humic-like substances capable of
complexing with and re-mobilizing heavy metals.
All of the major events selected to describe and separate these landfill
stabilization phases are encountered at one time or another in landfills
containing municipal refuse, provided that the associated microbially mediated
processes have been augmented by a sufficiency of moisture and nutrients and
are not being exposed to the inhibitory influences of toxic materials.
Because the manifestations of these phases often overlap within the usual
landfill setting, it has become customary to view them in a collective fashion.
Unfortunately, this tends to obscure reality and limit understanding of the
progression of events so requisite of design and operational attention. No
landfill has a single "age", but rather a family of different ages associated
with the various sections or cells within the landfill complex and their
respective progress toward stabilization. Moreover, the rate of progress
through these phases may vary depending on the physical, chemical and
microbiological conditions developed within each section with time. For
19
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example, acid conditions established during acid formation may preclude the
onset of active methane fermentation, microbial inhibition may be induced by
the presence of toxic substances, or high compaction may restrict the movement
of moisture and nutrients throughout the waste mass.
Indicator Parameters Descriptive of Stabilization Phases
There are certain indicator parameters or indices capable of being used
to detect and describe the presence, intensity and longevity of each phase of
landfill stabilization. Many of these apply to the analysis of leachate, so
that their facility is most evident when leachate production has commenced.
In addition, whether these analyses are physical, chemical or biological helps
to determine their applications and interrelationships within an overall
landfill perspective. For example, pH and ORP are physical-chemical
parameters indicative of respective acid-base and oxidation-reduction
conditions and critical to the proper evaluation of the acid formation and
methane fermentation phases; COD and 8005 are chemical and biological
parameters, respectively, but are both indicative of relative
biodegradability; and, nitrogen and phosphorus are chemical parameters
important to the determination of nutrient sufficiency and condition
(aerobic/anaerobic) of a particular phase. Similar importance can be ascribed
to other parameters which may reflect such factors as buffer capacity
(alkalinity), potential inhibition (heavy metals), ionic strength/activity
(conductivity), migration potential (chlorides), health hazards (bacteria and
viruses) and oxidizing potential (nitrates and sulfates).
Ranges in intensity or concentration of these parameters will vary
throughout the phases of stabilization, again depending upon the principal
function of each phase as described and the physical influence of dilution
with continuing ingress of moisture. This latter effect will tend to diminish
concentrations during leachate analysis, but will not influence the total mass
of leached constituents in time and space. Unfortunately, dilution effects
are often poorly recorded, leading to analytical variances in magnitude and
interpretation when analyses are based upon concentration alone.
Nevertheless, there are data available in the literature which may be employed
to provide general ranges of intensity and concentration of these indicator
parameters throughout those landfill stabilization phases when leachate is
available for analysis. Table 4 provides such a compilation for the four
previously defined landfill phases during which leachate and gas analyses are
critical for characterization and interpretation. These data have been
derived and arranged from literature accounts of a diverse group of primarily
laboratory or pilot-scale landfill simulations reviewed herein and presented
to indicate the magnitude of ranges encountered. Scrutiny of these data
indicates some obvious overlap between phases and also some contradictions of
the relatively discrete descriptions presented previously for each landfill
stabilization phase.
To better demonstrate this ability to match changes in leachate (and gas)
analyses with stabilization phases, and to use the results of such a procedure
to provide both didactic and operational interpretations of landfill behavior,
data from previously reported pilot-scale investigations of accelerated
landfill/leachate stabilization with leachate recycle (Pohland, 1980) have
20
-------
TABLE 1.
LANDFILL LEACHATE AND GAS CONSTITUENT CONCENTRATION RANGES ENCOUNTERED IN THE LITERATURE
AND THEIR RELATIVE SIGNIFICANCE TO THE DECREE OF LANDFILL STABILIZATION
Leaehata or Caa
Constituent
Biochemical Oxygen
Demand
(BOD5)
Chemical Oxygen
Demand
(COD)
Total Organic
Carbon (TOO,
mg/1
Total Volatile
Acids (TVA),
mg/1 as Acetic
Acid
BOD5/COD
Ratio
COD/TOC
Ratio
Total KJeldahl
Nitrogen (TKN)
mg/1
Nitrate Nitrogen
(NOj'-N),
mg/1
Ammonia Nitrogen
(NH3-N)
mg/1
NHj/TKN
Ratio
Total Phosphate
(POiT-P).
mg/1
Transition Phase
100-10,900
Influence of dilu-
tion and aerobic
solubllizatlon of
waste organics
180-18,000
Trending In a simi-
lar fashion to BODj
100-3,000
Beginning to appear
as a result of
aerobic solublllza-
tlon
100-3,000
Or just beginning to
appear as a result
of solublllzation
0.23-0.87
Increasing biode-
gradablllty of
organics due to
solubllizatlon
1.3-1.8
Low oxidation state
or organics
180-860
0.1-5.1
Increasing due to
oxidation of
ammonia
120-125
0.1-0.9
0.6-1,7
Phase of Biological
Acid Formation Phase
1,000-57,700
Accumulation of bio-
degradable organic
acids due to methano-
genlc lag
1,500-71,100
Trending in a similar
fashion to BODj
500-27,700
Increasing rapidly;
accumulation due to
methanogenic lag
Stabilization
Methane Fermentation
Phase
600-3,100
Conversion of biode-
gradable organics to
gaseous end products
(CHj4 and C02)
580-9,760
Trending in a similar
fashion to BOD;
300-2,230
Conversion of volatile
acids to methane;
decrease in aqueous
carbon
3,000-18,800 250-1,000
Solublllzation of orga- Conversion of fatty
nlc polymers to monomers; acids to fatty acid;
beta-oxidation to vola- fermentation of acetic
tile acids acid to methane
0.1-0.8
High blodegradablllty
2.1-3.1
Low to moderate oxida-
tion state of organics
«
11-1 ,970
Hay be low due to mi-
croblal assimilation
of nitrogenous com-
pounds
0.05-19
Decreasing due to re-
duction to ammonia or
N2 gas
2-1,030
Increasing due to
nitrate reduction and
protein breakdown
0-0.98
Protein breakdown; bio-
logical assimilation
0.2-120
Biological assimila-
tion and metal
complexation
0.17-0.61
Decreasing biodegradabl-
llty due to methanatlon
2.0-3.0
Moderate to high oxida-
tion of organics
25-82
Low due to flilcroblal
assimilation of nitro-
genous compounds
Absent
Complete conversion to
ammonia or Ng gas
6-130
Decreasing due to biolo-
gical assimilation
0.1-0.81
0.7-11
Low due to biological
assimilation
Final Maturation
Phase
1-120
Influence of high-
molecular weight
organic residuals
(humlcs, fulvlcs)
31 -900
Higher influence of
residual organics
than in BOD^ assay.
70-260
Influence of higher
molecular weight
organics (humlcs,
fulvlcs)
Essentially absent -
methanogenic system
undersaturated
0.02-0.13
Low degree of biode-
gradabillty
0.1-2.0
7-190
0.5-0.6
6-130
0.5-0.97
0.2-11
Overall
Range
(All Phases)
1-57,700
31-71,700
70-27,700
0-18,800
0.02-0.87
0.1-1.8
7-1.970
0-51
2-1,030
0.1
0.2-120
21
-------
TABLE 4 (Continued)
Total Alkalinity. 200-2,500
mg/1 S3 CaCOj
Solids (TS). 2,150-2,050
pH 6.7
Oxidation-Reduction «10 to *60
Potential (ORP),
mV
Copper, 0.085-0.39
mg/1
Iron, 68-312
mg/1
Lead, 0.001-0.004
mg/1
Magnesium, 66-96
mg/1
Manganese 0.6
mg/1
Nickel, 0.02-1.55
mg/1
Potassium, 35-2,300
mg/1
Sodium, 20,7,600
mg/1
Zlno, 0.06-21
mg/1
Total Conform. 10° to 1fl5
CFU/IOO ml
Fecal Conform, 10° to 105
CFU/IOO ml
Fecal Streptococci, 10° to !06
CFU/100 ml
110-9,650
Increasing due to
volatile acid forma-
tion and bicarbonate
dissolution
1,120-55,300
blllzatlon or organlcs
and mobilization of
metals
1.7-7.T
acid accumulation
•80 to -210
Decreasing due to the
depletion of oxygen
0.005-2.2
90-2,200
0.01-1. 14
3-1,110
0.6-11
0.03-79
35-2,300
0.65-220
10° to 105
10° to 105
10° to 106
760-5,050 200-3.520 110-9,650
Decreasing due to vola-
tile acid removal
2,090-6,110 1,160-1,610 1,160-55.300
6.3-8.8 7.1-8.8 1.7-8.8
tile acid removal and
bicarbonate dissolution
-70 to -210 *97 to »163 -210 to *I6
0.03-0.18 0.02-0.56 0.005-2.2
Decreasing (complexatlon)
115-336 4-20 1-2,200
Decreasing (complexatlon)
0.01-0.1 0.01-0.1 0. 001-1. 11
Decreasing (complexation)
81-505 81-190 3-1,110
Decreasing (complexatlon)
0.6 0.6 0.6-11
Decreasing (complexation)
0.01-1.0 0.07 0.02-79
Decreasing {complexatlon)
35-2.300 35,2,300 35-2.300
20-7,600
0.1-6.0 0.1 0.06-220
Essentially absent Absent 0-10^
Essentially absent Absent 0-1 0^
Essentially absent Absent 0-106
22
-------
TABLE 4 (Continued)
Viruses,
PFU/100 ml
Conductivity,
g mho s /cm
Essentially absent
2,150-3.310 1,600-17,100
Increasing due to mobi-
lization of metals
Essentially absent Essentially absent
2,900-7,700 1 ,100-4,500
Decreasing due to metals
complexation with
aulfldea
Absent
1,100-17,100
Chloride
CC1-),
mg/1
Sulfate
/ ert. - 1
KOUI4 ) ,
mg/1
Sulfide
(S-),
rag/1
Cadmium,
fflg/1
30-5 . ooo
Biologically stable;
good Indicator of
washout
10-158
aerobic oxidation
Essentially absent
190-190
30-5,000
Stable; good hydraulic
tracer
10-3,210
due to aerobic solubi-
llzatlon then decreas-
ing as anaerobic condi-
tions are established
0-818
Beginning to appear and
Increasing due to
sulfate reduction under
anaerobic conditions
70-3.900
30-5 , 000
Stable; good hydraulic
tracer
Absent
Complete conversion to
sulfides
0.9
Low due to heavy metal
precipitation
76-190
Decreasing due to com-
30-5,000 30-5,000
Stable; good hydraulic
tracer
5-10
Reappearing due to
aerobic oxidation
Absent
76-251 70-3,900
plexatlon and precipi-
tation
Chromium,
Olg/1
0.023-0,
.28
0.06-18
0.
Deere
05
as Ing
due
to
com-
0.05
0
.02-18
plexatton, precipita-
tion with au-Lfides
«
Carbon Dioxide,
I
Nitrogen Gaa,
J
Oxygen,
%
Hydrogen,
J
(aerobic metabolism)
0-10
decomposition of
organics
70-80
Influence of trapped
air
20
Influence of trapped
air
Essentially absent
in the presence of
oxygen
Transition to anaero-
10-30
waste decomposition
60-80
Decreasing due to dilu-
tion with C02
0-5
Decreasing due to
aerobic utilization;
shift towards anaero-
bic metabolism
0-2
Beginning to appear as
oxygen is depleted;
accumulates until
methanogeneals occurs
Suitable for energy
reco ery
30-60
methanogenesis Increases
<20
Artefact of trapped air;
den 1 tr 1 f Icat 1 on
0-5
Disappearing as methano-
genea la increases
<0.1
Maintained at low levels
by methanogenesis;
difficult to measure
Decreasing due to
and reversion to
aerobic metabolism
<10
>20
Increasing due to
introduction of air
>5
Increasing due to
introduction of air
0-2
Essentially absent
0-60
<20-80
0-20
Ranges of constituent concentrations were collected from the references and data presented in the Appendices.
23
-------
been reproduced and presented in Figure 3 for COD, total volatile acids (TVA),
pH, gas production and composition, and ORP; parameters considered as major
environmental factors within the landfill environment. Since these data were
obtained during municipal refuse stabilization after leachate had been
produced for recycle, they cover a time period extending from transition
(Phase II) to final maturation (Phase V), with the manifestations of acid
formation (Phase III) and methane fermentation (Phase IV) being most
pronounced.
In reality, most detectable landfill stabilization is accountable to the
processes occurring during Phases III and IV. With leachate recycle, the
consequences are magnified and reflected in the'indicator parameters over a
more contracted time interval than normally encountered at conventionally
managed landfills. Accordingly, high concentrations of organic contaminants,
represented by COD (shaded area) and TVA analyses, appeared inthe leachate
soon after leachate recycle was commenced (Time 0) as indicated in Figure 3.
Thereafter, the magnitude of these same parameters decreased as gas production
increased during methane fermentation, changing the initial ambient gas
composition to one dominated by methane and carbon dioxide. Similarly, the
formation and subsequent microbial conversion of volatile acids caused an
initial increase and decrease in COD. All of these changes are similar to
those occurring in many anaerobic biological treatment systems as they
progress sequentially through acid and methane fermentation phases. In
addition, since the experimental landfill used in these studies was
constructed similar to a discrete cell at a conventional landfill site, the
progress of stabilization (although accelerated by refuse shredding and
leachate recycle) reflected the landfill aging process for an analogous
section of a landfill where the two most active phases (Phases III and IV)
were essentially completed in about one year.
In actual landfills, the time periods associated with each phase and the
quality and quantity of leachate and gas will vary according to landfilling
procedures, the nature of the wastes, the amount of moisture allowed as input
to the landfill and closure and post-closure methods eventually applied.
Therefore, the time scale and concentration intensity for each of the five
phases indicated will vary from site to site. Nevertheless, Figure 3 serves
to illustrate the trends to be expected in the quality of both leachates and
gases produced with time. A careful analysis of associated project data from
a particular site can give a good indication of the existing "phase".
Moreover, a historical data base may allow prediction of lengths of phases and
facilitate a better planning and management of both leachate and gas handling
technologies as well as long-term maintenance.
24
-------
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-------
SECTION 6
TREATMENT OF LEACHATES FROM SANITARY LANDFILLS
GENERAL PERSPECTIVE
Most processes commonly employed for treatment of industrial wastewaters
have been tested for treatment of landfill leachates. These include the
traditional aerobic and anaerobic biological processes as well as a variety of
physical-chemical processes. Some of these processes are intended primarily
for the removal of organic contaminants, while others are best suited for
inorganics removals. Moreover, process performance in each case is related to
the chemical nature of the leachate utilized as influenced by the age of the
landfill as previously described and the miscellaneous factors previously
described. Accordingly, certain of the processes may be also used in pre- or
post-treatment applications.
The purpose of this section is to present a coordinated review of
biological and physical-chemical treatment process capabilities, following an
approach which segregates processes into bench-, pilot- and full-scale
categories and leachates into low-, medium-, and high-strength categories.
The review was organized to present the biological processes first (aerobic,
then anaerobic), followed by physical-chemical processes including applica-
tions of coagulation, oxidation, ionizing radiation, ion-exchange, adsorption,
and reverse osmosis.
AEROBIC BIOLOGICAL TREATMENT OF LANDFILL LEACHATE
The operation and evaluation of biological treatment processes are
dependent upon the ability to monitor and control certain process variables.
Considering carbon as the limiting nutrient in biological treatment systems,
the design and operational variables of primary interest are those which
reflect the rates of carbon utilization exhibited by a given cellular mass or
reactor volume. The corresponding rates of biomass generation are also of
interest with respect to the maintenance of a stable biological population and
sludge disposal considerations.
Four kinetic parameters are generally used to describe the growth of
microorganisms in response to the availability of a limiting substrate. These
include the maximum specific cell growth rate (vmax)» the cell decay
coefficient (b), the saturation coefficient (Ks), and the cell yield (Y).
Operation in continuous culture requires a dynamic balance of substrate and
cellular variations. In addition, substitution of classical Monod kinetic
expressions containing the four variables mentioned above into a mass balance
expression gives rise to several operational parameters. These include the
mean cell residence time (6C), the volumetric organic loading rate (OLR), and
26
-------
the food to microorganism ratio (F/M) which is a cellular organic loading
rate.
Process performance in response to manipulation of these operating
variables is evaluated by comparing effluent organic concentrations to
influent concentrations and to existing effluent limitations. Therefore, the
treatment evaluations presented reflect COD and BOD^ removals as well as
effluent COD and 8005 concentrations. In addition, nitrification/
denitrification, metals removal, and sludge characteristics, also important
considerations in the treatment and disposal of leachates, are discussed in
each treatment section depending upon information available.
Bench-Scale Aerobic Treatment Studies
A list of references pertaining to aerobic biological treatment of
landfill or lysimeter leachates is presented in Table 5. The reactor con-
figurations, research objectives and operating protocols associated with each
study are also presented in the table.
Activated .Sludge—
Activated sludge and its process variations have become well established
for the treatment of municipal and many industrial wastewaters. Its wide
ranging success in treating these wastewaters has encouraged a number of
preliminary evaluations of its effectiveness in treating leachate. However,
due to the wide variation in quality of leachates and in activated sludge
operational protocols, results from these studies tended to be somewhat
diverse. Therefore, comparisons of process performance in terms of effluent
organic concentrations and percentage removals were arranged to reflect
results from three different influent organic strength categories.
Accordingly, the effects of 9C, organic loading rates, and other process
variables were determined for low-, medium-, and high-strength leachate
categories and concomitant concentration ranges indicated in Table 6.
TABLE 6. LEACHATE ORGANIC STRENGTH CATEGORIES
Leachate Strength
Category
Concentration Ranges, tng/1
COD Basis 8005 Basis
Low-Strength
Medium-Strength
High-Strength
<1,000
1,000-10,000
10,000
220-750
750-1,500
1,500-36,000
Effect of Mean Cell Residence Time (9^)—Following the segregation of
bench-scale activated sludge treatment data into the categories listed in
Table 6, the influence of mean cell residence time on process performance was
investigated by plotting 6C versus effluent 6005 and COD concentrations and
versus percentage removals. The resulting performance of bench-scale
activated sludge units at 22-25°C is illustrated in terms of 6005 in Figure 4.
The data presented in Figure 4 (summarized in Appendix Table A-l) suggest that
the limiting 6C, defined as that incurring an organic removal efficiency of
27
-------
TABLE 5. BENCH-SCALE RESEARCH ON AEROBIC
LEACHATE TREATMENT PROCESSES
txj
co
REFERENCE
19,20,
195
PROCESS* PROCESS DESCRIPTION
AS Complete-mix, continuous flow,
extended aeration reactor
system, daily fill and draw
reactor operation.
RESEARCH OBJECTIVE(S)
Effect of 0C and BODc and COD
loading on BOD and COD removal
efficiencies.
LEACHATE
SOURCE**
Landfill
28
35,143
26
40,42,44,
45,70
53,54,97
118,119
151
193,194
AS
AS
AL
RBC
TF
AS
AL
AL
AS
AS
AS
AS
Complete-mix, continuous
flow reactor operation.
AS: Complete-mix, batch and
continuous flow reactor; AL:
Complete-mix, continuous flow
reactor operation; RBC: Plug
flow, continuous flow reactor
operation; TF: Complete-mi x_,
continuous flow reactor
operation using plastic contact
media.
Not given.
Complete-mix, daily fill and
draw extended aeration
reactor system.
Complete-mix, continuous
feed, reactor operation
Complete-mix, daily fill and
draw reactor operation.
Complete-mix, continuous
flow reactor operation.
Complete-mix, continuous
flow reactor operation.
Effect of phosphorus addition,
influent dilution and 0 on BODr
and COD removal efficiencies;
determine kinetic parameters.
Effect of COD loading and
influent COD concentration on
COD removal efficiency; influence
of chemically pretreated influent.
Effect of e on BODg efficiencies
and metal removal .
Effect of T on COD and TOC
removal; nutrient addition
effect; metals removal; sludge
characteristics.
Effect of 0 on BOD,, COD, and
TOC removarefficieficy, kinetic
parameter determination.
Effect of temperature and 6
on organic removal efficiency.
Effect of 6 on COD and TOC
removal efficiencies; metal
removal efficiency; determine
kinetic parameters.
Determine kinetic parameters .
Landfill and
lysimeter
Landfill
Landfill
Landfill and
lysimeter
Landfill
Lysimeter
Landfill and
lysimeter
Lysimeter
205,206,207 AS Complete-mix, continuous
flow reactor operation-
Effect of 9 on BOD5, COD, TOC Landfill and
and metal removal efficiencies', lysimeter
determine kinetic parameters.
-------
TABLE 5 (Continued)
230 AS Not given.
28,232 AS Complete-mix, continuous
flow reactor operation.
230 AS Complete-mix, continuous
flow reactor operation.
244 AS Complete-mix, continuous
AL flow reactor operation .
260,261 AS Complete-mix, daily fill
and draw reactor operation.
269,270,271. AS
176
272
288,289, AS
290
291
163
Complete-mix, daily fill
and draw, extended aeration
reactor system.
AL Complete-mix, continuous
flow reactor operation.
Complete-mix, daily fill
and draw reactor operation.
AS Complete-mix, fill and
draw reactor operation.
Complete-mix, fill and
draw reactor operations.
Effect of 6C and BODg and COO Landfill
loading on BOD,, and COD removal
efficiencies; effect of nutrient
adjustment.
Iron removal using ferrous iron Lysimeter
metabolizing bacteria.
Effect of chemical pretreatment Lysimeter
on COD removal efficiency.
Effect of temperature, ec, BODg Landfill
loading, and BOD/COD on BOD5
and COD removal efficiency;
compare results of full-scale
and bench-scale studies.
Determine nutrient require- Lysimeter
ments for BODg and metal
removal efficiencies.
Effect of 0C and F/M on BODg, Lysimeter
COD and metal removal effi-
ciencies; determine kinetic
parameters.
Effect of 0C on BOD and TOC Landfill
remvoal efficiencies.
Effect of temperature and 0 Lysimeter
on BOD5 and COD removal
efficiencies; effect of Qc
on effluent polishing.
Effect of fill and draw cycle Lysimeter
on BOD5 and COD removal effi-
ciencies and sludge character-
istics.
Effects of ec on organics, Landfill
metals and nitrogen
conversion.
*AS = Activated Sludge
AL = Aerated Lagoon
**A11 leachate sources involve the use of municipal solid
waste
TF = Trickling Filter
RBC = Rotating Biological Contactor
-------
8000
6ooo
uooo
aooo
§
m
i ri
M
20C
100
0
~D j
• D LEGEND
O tow Influent, BOD,: 2
(References 205,244,2
— C3 Medium to High BOD- :
(References 19,26,28,
• Nutrient Adjusted BOD
D
°
" \
I
to -=r^
\
El \
0 \
D \
a \v
e ^^^-^.t
-OH
) B E
»'^'l. .5 ^D . ?fls , ,
r
10
15
20 30 UO SO 60
a a a
Mean Cell Residence Tine (9C>, days
5 10 15 * 20 30 40 50 60
Mean Cell Residence Tim* (Sc), days
Figure 4. Relationship Between 0C and BOD^ Removal for
Bench-Scale Activated Sludge Studies
-------
90% or greater and/or an effluent 8005 of 200 mg/1 or less, ranged between
6 to 10 days. (It should be noted that many researchers did not include the
BOD5 assay in their monitoring programs. The COD and/or TOG analyses were
generally preferred and, in spite of the advantages in simplicity and accuracy
offered by these analyses, they did not necessarily reflect differences in
leachate biodegradability.)
The effects of 8C on process performance is illustrated on a COD basis in
Figure 5. The data presented, also summarized in Appendix Table A-l,
similarly suggest a limiting 9C of 6 to 10 days. Compared with BODjij-based
analysis, the COD data suggest that significant process improvement may be
available using extended retention times (10-12 days). However, even at
retention times exceeding 10 days, effluent COD concentrations typically
remained above 300 mg/1 and effluent BOD^ concentrations ranged from 10 to 100
mg/1. Residual COD may be attributed to refractory organics such as humic-
and fulvic-like substances (Chian and DeWalle, 1977a, 1977b; Chang, 1982).
In addition to segregating the data based on influent concentration, the
data were also divided into three biodegradability ranges with BOD^/COD ratios
of <0.50, 0.50-0.75, and >0.75 being characteristic of low-, medium-, and
high-strength leachates, respectively. The data were similarly divided with
COD/TOC <2.0 for low-strength, 2.0 < COD/TOC < 3.0 for medium-strength, and
COD/TOG >3-0 for high-strength leachate. Percent COD removal was used to
evaluate the effects of biodegradability on treatment performance, since it
was the most commonly analyzed indicator of organic content in the leachates.
As anticipated, examination of the effects of 9G and biodegradability on
process performance using these ratios (Figure 6) indicates that the
higher-strength leachates were more amenable to treatment at lower retention
times than lower-strength leachates. As before, a limiting 9C in the range of
5 to 10 days was suggested by the COD removal data.
Organic Loading Effects—The organic loading applied to bench-scale
activated sludge processes was the second operational variable evaluated with
respect to its effects upon effluent organic content (8005, COD) and removals.
As in the 9C evaluation, the performance data were segregated into low-,
medium-, and high-strength leachate categories using both influent 8005 and
COD concentrations and BOD5/COD and COD/TOC ratios.
The influences of two kinds of organic loading rate on activated sludge
process performance were evaluated. The first was the volumetric organic
loading rate, which is based upon the hydraulic retention time and is
commonly referred to as the organic loading rate (OLR). The second loading
rate is based upon the mass of microorganisms in the reactor as well as the
hydraulic retention time. This latter loading rate is commonly referred to as
the food-to-mass (microorganism) ratio, F/M.
Illustrations of the influence of OLR on 8005 and COD are presented in
Figures 7 and 8, respectively. Data presented in these figures (Appendix
Table A-2) do not exhibit very clear trends, although it may be suggested that
the limiting OLR was on the order of 1 to 2 kg BOD5/m3-day. The COD data are
particularly diverse, making an analysis of process trends on this basis
difficult. Even when further segregated into biodegradability categories
using BOD^/COD and COD/TOC ratios (Figure 9), no clear trend is discernible
31
-------
15,000_
10,000 -
5,000-
2.000 -
1.500 -
1,000 -
LEGEND
O Low Influent COD: < 1000 mg/1
(References 35,205)
Q Medium Influent COD: 1000-10,000 mg/1
(References 19,26,28,35,151,222,228,244)
A High Influent COD: > 10,000 mg/1
(References 54,119,244,270,290)
• Nutrient Adjusted BOD5:N:P - 100:5:1
20 30 UO 50 60
1001~
Mean Cell Residence Time («,.),
5 10 15 20 30 UO 50 60
Mean Cell Residence Time (80), days
Figure 5. Relationship Between 6 and COD for Bench-Scale
Activated Sludge Studies
-------
100 p-
30
60
o a
o
a o
3 ED O 133
20
*«
ff
3
O Low Biodegradabilicy: 80D;/COD < 0.5
(References 19,28,54,244)
Q Medium Biodegradabilicy:
BODj/COD 0.5 to 0.75
(References 19,26,28,35,119,205,222,228,244,270,290)
A High Biodegradability: BOD./COD > 0.75
(References 19,28,35)
. Nucrienc Adjusced BOD3:N:P - 100:5:1
t A
'
I
I
II
I
10
Maon Call taaidanca Tin*
100 —
80
a
8
20 -
20 30 40 50 60
.). d*y«
A^ A A
0 Low Biodegradabilicy: COD/TOC < 2.0
(Reference 205)
Medium Biodegradabilicy: COD/TOC 2.0-3.0
(References 151,222,223)
High Biodegradability: COD/TOC > 3.0
(References 28,35,54,119,151,270,290)
Nutrient Adjusted BODj:S:P - 100:5:1
1 LO 1 1 I I j
5 10 15 ' 20 30 Uo 50 60
Mean Call Residence Tina (9C),
Figure 6. Comparison of 9C vs. COD Removal
Data Segregated According to
Biodegradability Ratios BOD/COD
and COD/TOC
33
-------
8000
QUUU
6000
4000
CO
a
Jf 2000
Q
CO
g 1000
l-l
IS
<•> 300
OJ
-p-
200
100
0
D
a LEGEND
O Low Influent, BOD.: 220-250 mg/1
_ (References 205,244,272)
D Medium to High BOD,: 1500-36000 mg/1
(References 19,26,28,35,119,222,224,228,270)
. Nutrient Adjusted BOD5:N:P - 100:5:1
100
a
r a 8°
a
a B
* 60
|
*> ItO
a
3
_ 20
B
on o
a Q
fefifeBBP0- "3 B °Q
Q a i * t l A i n
~ QCEfcCCfiH^ ^ 3 Q 0 Q
UU n
»tl ° B
O
D 0
— a
a
0 0
a
_
1 1 1 n I A
1 2 3
BOD5 Loading, Kg/m'-day
...90S
4—?
BOD5 Loading, Kg/m3.day
Figure 7. Relationship Between Organic Loading Rate and BOD5
Removal for Bench-Scale Activated Sludge Studies
-------
10,000
LEGEND
5,000
O Lou Influent COD: < 1000 mg/1
(References 35,205)
Q Medium Influent COD: 1000-10,000 mg/1
(References 19,26,28,35,151,228,241)
A High Influent COD: > 10,000 mg/1
(References 54,119,244,270,290)
. Nutrient Adjusted BOD5:N:P - 100:5:1
2,500
2,000
1,500
1,000
500
a
0 8
a
cPD
a
D
I
_L
100
80
60
a
8
20
I I I
On
i
i
2 3 ' 5 10 15 20
COD Loading, Kg/m3-day
•V
2 3
COD Loading, Kg/in3-day
1 A! i
I
5 10 15 20
Figure 8. Relationship Between Organic Loading Rate and COD Removal
for Bench-Scale Activated Sludge Studies
-------
COD Removal,
(C
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5
-------
with the COD loading data. However, successful operation has been
demonstrated for both medium- and high-strength nutrient-amended leachates at
loading rates up to 15 kg COD/m3'day. For raw leachates, successful operation
was only evident for loading rates approaching 2 kg COD/m^-day.
The effects of varying F/M are represented in Figures 10 and 11 for BOD5
and COD loadings, respectively. Limited F/M data (Appendix Table A-3) were
available since not all researchers included mixed liquor volatile suspended
solids (MLVSS) analyses in their monitoring programs. The 6005 data which are
available (Figure 9) suggest that the limiting F/M may be on the order of
0.2 to 0.4 kg BOD5/kg MLVSS-day. However, successful operation using
nutrient-adjusted leachate has been demonstrated at loading rates beyond 0.5
kg BOD5/kg MLVSS-day. Examination of the COD data (Figure 11) suggests
similar trends; effluent COD values increased to above 700 mg/1 at loading
rates in excess of 0.4 kg COD/kg MLVSS-day. COD removals for medium- and
high-strength leachates remained above 90% at this loading rate. As
demonstrated using the OLR, nutrient amendments allowed for successful
operation up to 1 kg COD/kg MLVSS-day.
Effects of Temperature—The effects of temperature on the performance of
bench-scale activated sludge units were evaluated by comparing effluent COD
concentrations and percentage removals at temperatures ranging from 5° to 25°C.
However, since these performance parameters are also dependent on 9C and the
influent concentration, the data shown in Figure 12 are also compared with
regard to these variables. Accordingly, the data are grouped into the three
influent strength categories previously used and into three 6C categories as
well. As indicated in Figure 12, these include: 9G <4 days; 9C = 6 to 10
days, and, 9C >12 days.
Due to these and other operational variables, the effects of temperature
are not clearly discernible, although the trend appears to be an expected
increase in organic removal with increasing temperature. Successful operation
has been demonstrated for 9C >6 days at temperatures as low as 5°C. However,
lower effluent COD concentrations resulted at the higher temperatures.
Heavy Metal and Alkaline Earth Metal Removal—Some researchers have
included metals analyses in their monitoring protocol to evaluate the
effectiveness of activated sludge in removing these constituents from
leachates. As shown in Table 7 and Appendix Table A-4, the activated sludge
process was effective in removing the majority of the heavy metals monitored.
In particular, zinc, iron, manganese and cadmium were removed by 95% or
greater. Chromium and lead were also fairly well removed (80-90?). However,
nickel removals were generally low and on the order of 60%. Metal removal
during aerobic treatment may be enhanced by the oxidation of metals, e.g.,
Fe+2 to Fe+3, to forms which precipitate more easily at the pH of ranges of 8
to 9 commonly encountered during activated sludge leachate treatment.
The alkaline earth metals were removed, but to a lesser degree than
observed for the heavy metals during normal activated sludge operation. As
again shown in Table 7 and Appendix Table A-4, calcium and magnesium removals
ranged from 3 to 99%, but were typically in the range of 40 to 70%. Potassium
and sodium removals were typically on the order of 20 to 40?.
37
-------
3000
oo
500
llOO
300
200
100
LEGEND
O Low Influent BOD5: 220-750 mg/1
(Reference 205)
O Medium to High Influent BOD5:5170-36,000 mg/1
(References 119,222,224,261,270,290)
• Nutrient Adjusted: BODj:N:P - 100:5:1
BO
O3
0.2
0.14
0.6
0.8
Food to Microorganism'Ratio (F/M),
Kg BODs/ Kg MLVSS-day
100
80
60
Uo
20
1.0
DO GH
a
- -O- - .
. qnv,,.
O
0.2
O.U
0.6
0,8
1.0
Food to Microorganism Ratio (F/M),
Kg BOD5/ Kg MLVSS-day
Figure 10. Relationship Between Food to Microorganism
Ratios (F/M) and BOD5 Removal for Bench-Scale
Activated Sludge Studies
-------
3500 _
u>
J^UU
3000
2500
i-t
% 2000
cT
8
•P
i
3
H 1500
w
1000
500
0
0
&
LEGEND
O Low Influent COD: < 1000 rag/1
(References 35,194)
D Medium Influent COD: 1000-10,000 mg/1
— (References 28,35,141,222,224,290)
A High Influent COD: > 10,000 mg/1
(References 54,119,224,270,290)
• Nutrient Adjusted: BODj:N:P = 100:5
~ 100
D
80
0
-a eo
W
a
0 D A 1
— « ItO
i
a o Q
if* a A H
~ A A D A H 20
» A A A°
o Q aQ a
« oa
an *? a aa
*?. 1 1 1 ^ i 1 1 1 ) n
°-2 O-1* 0.6 ' U 8 12 16 20
r~ »&A
^'^^^a ^jjf arf^ A Q A
& B Q O Q
k _ Q 90*
0°° B
Q Q
El
O
- D a
Q
_ a
—
1 1 1 A 1 1 1 I i
0 0.2 O.U 0.6 r It B 12 16£0
Food to Microorganism Ratio (F/M)
Kg COD/ Kg MLVSS-day
Food to Microorganism Ratio (F/M),
KgCOD/Kg MLVSS-day
Figure 11. Relationship Between F/M Ratio and COD Removal for
Bench-Scale Activated Sludge Studies
-------
100
so
§
20
if *
90*
10
15
20
25
2500
2000
1500
LEGEND
O Low Influent COO: < 1000 mg/1
(Reference 35)
Q Medium Influent COD: 1000-UK000 ng/1
(References 33,222)
A High Influent COD: > 10,000 mg/1
(References 119.290)
. Nutrient Adjusted: BODj:N:P - 100:5:1
Opened symbols: 9 <4 days
Half-shaded symbols: 9 • 6-10 days
Shaded symbols: 9C - 12-45 days
25
Figure 12. Relationship Between Temperature and COD Removal
for Bench-Scale Activated Sludge Studies
40
-------
TABLE 7. SUMMARY OF HEAVY METAL AND ALKALI AND ALKALINE EARTH METAL
REMOVAL DATA FOR THE BENCH-SCALE ACTIVATED SLUDGE PROCESS
Heavy metals
Cd Cr Fe Pb Mn Nl
Influent
Concentration Range, rag/1
Removal Range, t
Average Removal, %
Alkali and Alkaline
0.04-0.1 0.1-1.9
85-99 75-98
96 92
Earth Metala
240-2130 0.17-1. 41
96-99 82-98
98 89
13-41 0.18-0.65
90-99 39-75
97 60
31-220
96-99
99
Ca Mg K Na
Influent
Concentration Range, og/1
Removal Range, I
Average Removal, t
88-3780
64-99
90
35-660
3-90
52
200-1060
8-46
27
430-1350
0-35
16
Nitrification — Nitrification of leachates in the activated sludge process
has been studied in depth by only one researcher (Johansen, 1975), although
other investigators have provided TKN, ammonia, and nitrate data as shown in
Appendix Table A-6. The effluent ammonia content of these leachates was
typically 200 to 300 mg/1 unless amended with nutrients. The general
performance of bench-scale activated sludge systems with emphasis on
nitrification is illustrated in Figure 13. Since nitrifying bacteria will
typically have lower growth rates than carbonaceous bacteria, longer 0C are
needed for complete nitrification. As shown in Figure 13, 9C of 10 days or
longer were necessary to achieve better than 90% nitrification at temperatures
above 12°C. At lower 9C, viz., in the range of the limiting 0C (6-10 days)
for BODij , 60 to 80% nitrification was typically encountered.
Air stripping of NHg was believed to have occurred during one activated
sludge study (Uloth and Mavinic, 1976). In this study, 96 to 99% of NH3 was
removed through aeration of the activated sludge units. The study was
performed at 23 °C and a pH of 8.5 to 8.8 and, although this pH was not as high
as advocated for conventional stripping, the long detention times of 10 to 60
days and high NHg levels (1400-1800 mg/1) may have enhanced the effectiveness
of ammonia removal by this mechanism.
Combined Treatment with Municipal Wastewater — The combination of
industrial wastewaters with larger volumes of municipal wastewater has proven
to be a successful treatment strategy on both bench- and pilot-scale (Table 8).
Combined treatment may provide a better effluent as a result of the
maintenance of a more heterogeneous population, the increased availability of
nutrients, and the dilution of potential inhibitors.
41
-------
TABLE 8. BENCH-SCALE RESEARCH PERFORMED ON COMBINED TREATMENT OF LEACHATE
AND DOMESTIC MASTEWATER bSING Tut ACTIVATED SLUCGE PROCESS.
REFERENCE
PROCESS DESCRIPTION
PROCESS OBJECTIVE(S)
LEACHATE
SOURCE
19,20
42
43
44.45.69,
70,286
176,260,
261
Semi-continuous, complete-mix,
extended air reactor.
Plug flow reactor for control
and test unit operated at
equivalent F/M.
Plug flow reactor.
Three complete-mix, continuous
flow reactors in series to
simulate a plug flow reactor.
Complete-mix, continuous
flow reactor.
Complete-mix, daily fill
and draw reactor.
Determine optimum leachate to
domestic wastewater ratio for
organic removal; evaluate
sludge production.
Evaluate effect of adding 0.5*
leachate to domestic wastewater
for same F/M as domestic waste-
water only case; characterize
sludge settling characteristics.
Study sequential uptake of diffe-
rent organic components.
Determine optimum leachate to
domestic wastewater ratio for
constant F/M, optimum F/M for
constant ratio based on organic
removal; characterize sludge
settling properties.
Effect of shockloading of leachate
to activated sludge process;
evaluate sludge settling charac-
teristics.
Determine optimum BOD5:N:P ratio
for various leachate to domestic
wastewater ratios,- characterize
metal content in sludge.
Landfill
Lysimeter
and landfill
Lysimeter
Lysimeter
and landfill
Synthetic
leacnate made
of sodium
acetate, acetic
acid, glycine
and pyrogallol
Lysimeter
100 _
80
60
20
_L
4-
LEGEND
O T - 5-10
(Reference 35)
D T - 12-16°C
(Reference 35)
AT- 18-25°C
(Reference: 35,119,191,211)
Opened symbols: Activated sludge
Shaded symbols: Aerated lagoon
J_
j_
10 15
MMB Cell H««id«nce
20 30 "*0 50 60 ,
(•<.) ,
-------
Since only one pilot-scale study has been reviewed, pilot- and bench-
scale studies were considered together. As indicated in Appendix Table A-7, a
number of leachate to domestic wastewater volume ratios (L/D, expressed as %
leachate) have been studied, resulting in a fairly broad range of organic
influent strengths (150-3640 mg/1 BOD5).
Combined treatment of leachates was successful in removing 98 to 99%
and 95% COD, although greater air requirements were generally reported.
Increases as high as 400? and 800? in oxygen availability have been found
necessary for successful treatment at 10% and 20% leachate to domestic
wastewater (L/D) fractions, respectively, over the oxygen used in the domestic
wastewater control (Boyle and Ham, 1972, 1974). Solids production was also
higher, resulting in 300? and 800? more solids at 10? and 20? leachate to
wastewater ratios, respectively. Moreover, sludge settleability was
negatively affected by leachate introduction. Settling velocities for 1 to 3%
L/D were determined to be about one-half of the control settling velocities by
Chian and Dewalle (1976, 1977) and DeWalle and Chian (1977). Furthermore,
excessive sludge bulking has been noted for L/D of 5,10, and 20? with a
sludge volume index (SVI) of 100, 200 and 1000? higher than the control (Boyle
and Ham, 1972, 1974).
Figure 14 provides an illustration of the relative success of combined
leachate/wastewater treatment in terms of effluent organics (8005, COD) and
removal percentages. However, these data plots fail to reveal sludge handling
difficulties and a consideration of them would lead to more conservative
conclusions regarding the feasibility of this approach. Therefore, when
sludge handling is considered, it appears that an L/D of less than 5? is
required to apply this treatment strategy.
Aerated Lagoon—
Aerated lagoons are similar in many respects to activated sludge systems.
Both processes utilize mechanical or diffused aeration to provide oxygen
and mixing. Although not as widely practiced, aerated lagoons may also employ
biomass recycle to increase cell retention time (0C) in a fashion similar to
the activated sludge process. However, aerated lagoons are more typically
operated as single-pass reactors with long hydraulic retention times.
Organic substrate (8005, COD) removal was again utilized as the primary
indicator of aerated lagoon process performance. The data presented in
Figures 15 and 16 were segregated according to temperature. Most of the
studies involved medium- to high-strength leachates, characterized by influent
COD concentrations of 6400 to 9840 mg/1 and BOD5/COD ratios of 0.4 to 0.7 as
indicated in Appendix Table A-8. Long retention times ranging from 7 to 100
days were used in the studies, and most were greater than 10 days. Therefore,
the relationships between 8005 and COD removals and retention times (T) for
the aerated lagoon studies shown in Figure 15 were not particularly
instructive. Temperature effects were also nondiscernible due to the long
retention times.
43
-------
40 _
20
o
o
pa
LEGEND
O Bench-Scale: T-22-23°C
(References 12,145,261)
Q Pilot-Scale: T-10-15°C
(Reference 228)
200
150
100
no
o"
8
I 50
o o
_L
LEGEND
3 Bench-Scale: T-22-23°C
(References 19,1)2,1)5)
3 Pilot-Scale: T-10-15°C
(Reference 228)
I
J
0 5 10 ' 20
Leachate/DooesClc Wastewater (L/D),2
100
75
o
o
CO
50
25
O O
a
0 5 10 ' 20
Leachate/Domestic Uastewater (L/D),2
lOOf
90Z
75
a 50
LEGEND
O Bench-Scale: T-22-23°C
(References 12,15,261)
O Pilot-Scale: T-10-15°C
(Reference 228)
o
o
u
25
I
I
O O o
o a
•Q-
90Z
LEGEND
O Bench-Scale: T-22-23°C
(References 19,12,«5)
D Pilot-Scale: T-10-15°C
(Reference 228)
0 5 10 20
LeachaCe/Domestic Wastewater (L/D),%
0 5 10 20
Leachate/Domestic Waateuater (L/D) %
Figure 14. Relationship Between Leachate/Domestic Wastewater
Volume Ratio and Organics (BODg, COD) Removal for
Bench- and Pilot-Scale Combined Wastewater
Activated Sludge Studies
-------
Ln
J.UU
80
60
*-«
i
a kO
S.
Q
g
20
0
A A A
90X
A
80
60
M
's
8 1(0
LEGEND "s
n
O T - 5°C 8
(Reference 211)
AT- 20-23°C
(Reference 26)
20
1 1 1 1 1 0
0 20 ItO 60 80 100
A &. * & 4A AA &
O O o 90!{ O
LEGEND
O T - 5°C
n (Reference 35)
D T - 12°C
a (Reference 35)
AT- 20-23°C
(Referencea 35,1)5.211)
• Nutrient Adjusted:
COO:N:P-161:8:1
1 1 1 1 |
3 20 ItO 60 80 ICO
Detention Time (T), days
Detention Time (r), days
Figure 15. Relationship Between Hydraulic Retention Time (T) and Organics
Removal for Bench-Scale Aerated Lagoon Studies
-------
100
80
60
U°
20
0 ~
LEGEND
O T - 5°C
(Reference 211)
AT- 20-23°C
(Reference 26)
1
90%
0.25 0.50 0.75
BOD5 Loading, Kg/m3-day
1.0
1.25
80
60
1(0
20
LEGEND
D T - 5°C
(Reference 35)
3 T • 12°C
(Reference 35)
& T - 20-23°C
(References 35,15,211)
. Nutrient Adjusted:
COD:N:P-161:8:1
J L
90%
1.0 2.0 3.0
COD Loading, Kg/m3-day
U.O
5.0
Figure 16. Relationship Between Organic Loading Rate and Organics Removal
for Bench-Scale Aerated Lagoon Studies
-------
Figure 16 provides an illustration of a similar lack of trend between
organic loading and the performance of aerated lagoon processes. Loadin
rates as high as 1 kg BOD5/m3-day or 5 kg COD/m3-day provided 90% or bet er
BOD5 and COD removal at 20 to 23°C.
Fixed-Film Processes—
The trickling filter and rotating biological contactor (RBC or biodisk)
have been evaluated by only one investigator (Johansen, 1975). Unfavorable
results were obtained in either case. However, a chemically precipitated
leachate was used in the trickling filter study and also in one of two biodisk
studies as indicated in Table 9. The raw leachate used in the other biodisk
study was also a lew-strength leachate characterized by a COD of 730 mg/1 and
COD/TOG ratio of 3-7. Retention times utilized were also very low.
Therefore, this isolated study should probably not be construed as conclusive
evidence that these processes are inapplicable. Given additional investiga-
tive evidence, these process options may also represent viable leachate
treatment alternatives.
TABLE 9. EXPERIMENTAL CONDITIONS AND PERFORMANCE DURING TRICKLING FILTER
AND ROTATING BIOLOGICAL CONTACTOR TREATMENT OF LEACHATE
Leachate*
Influent BOD5, mg/1
Influent COD, mg/1
Influent TOC, mg/1
BOD5/COD
COD/TOC
BOD5 Loading
COD Loading
BOD5 Removal, %
COD Removal, %
TOC Removal, %
BOD5:N:P
PH
Trickling
Filter
CP*
50
380
114
0.13
3.3
0.1 kg/m3-day
0.9 kg/m3-day
-
7.4
7.5
100:200:0.2
7.2-9.1
Rotating Biological
Contactor
CP
50
400
114
0.13
3.5
0.78 g/m2-day
6.2 g/m2-day
-
16
24
100:200:0.2
7.0-8.9
R
_
730
200
-
3.7
1 .8 g/m^-day
-
47
44
-
8.0-8.7
Temperature, °C
Reactor Type**
Recycle Ratio
T, hours
17
CSTR
100
9
17
PFR
0
7
11
PFR
0
45
= Data not given
*CP = Chemically pretreated
R = Raw leachate
**CSTR = Continuously-stirred tank reactor
PFR = Plug flow reactor
47
-------
Kinetic Parameters for Bench-Scale Aerobic Processes—
Kinetic parameters associated with Monod-type expressions have been used
to describe and understand microbial growth and substrate removal patterns
associated with waste treatment processes. These kinetic parameters have been
determined by a number of researchers from their experimental data as
summarized in Table 10. The kinetic parameters of interest were cell yield
(Y), decay coefficient (b), maximum specific growth rate ()%ax)» and the
saturation constant (Ks).
Similarities and dissimilarities existed when comparisons were made
between parameter values for leachate and domestic wastewater, and for various
influent substrate concentrations. The yield, Y, was fairly consistent,
ranging from 0.29 to 0.59 mg VSS/mg 8005 or COD. However, the decay
coefficient, b, was found to be variable, 0.002 to 0.336 day"1, which might be
attributed to inhibition by high NHi|+, heavy metals or organic concentrations.
Phosphorus limitation would also cause a higher decay rate. Maximum growth
rates (Mmax^ were also determined to be variable and to be both less than and
greater than the typical values for domestic wastewater. Reported ymax values
for leachate treatment ranged from 0.02 to 16 day"1 based on BOD^ or 0.3 to 24
day~1 based on COD, as compared to 1 to 8 day"1 and 4 to 11 day"' for
wastewater on 8005 and COD bases, respectively. The saturation constant, Ks,
was the most variable parameter and was usually higher for leachates than
typical values for domestic wastewater. This was partly attributed to the
organic complexity and, therefore, more refractory nature of the leachate as a
substrate.
Pilot- and Full-Scale Aerobic Treatment
Activated Sludge (AS), aerated lagoons (AL), and stabilization ponds (SP)
have been investigated for the treatment of landfill leachates on pilot- and
full-scale. A listing of pertinent literature citations for four activated
sludge, four aerated lagoon, and four stabilization pond studies is provided
in Table 11.
Activated Sludge—
As indicated in Table 11, the activated sludge process has been used on
pilot- and full-scale for the treatment of leachate at four landfill sites. A
summary of the leachates produced at each site and details of each AS
configuration studied are presented in Table 12. The data in Table 12 have
been separated into influent and effluent quality, pretreatment, treatment,
post-treatment, and sludge characteristics sub-categories. Within the
influent and effluent quality category, 8005 and COD data have been included
to represent organic constituents, and iron has been included to reflect heavy
metals behavior. Ammonia and TKN data were also included to evaluate the
possible occurrence of nitrification.
The activated sludge processes summarized in Tables 11 and 12 have been
fairly successful for the removal of organics and somewhat less successful for
the removal of metals such as iron. In West Germany, 94 to 9Q% 8005 removal
was consistently achieved at a ec of 12 days, even at temperatures as low as
6 to 7°C (Scherb, 1981). The facilities at Bucks County, PA (Steiner, et al.,
1977 a,b, 1979, 1980; Stoll, 1979) have tested a number of operating
strategies including NH^ stripping as a pretreatment measure, the use of two
tanks in series or parallel operation, and nutrient additions. The results of
48
-------
TABLE 10. SUMMARY OF MONOD KINETIC PARAMETERS FOR ACTIVATED SLUDGE TREATMENT OF LEACHATE
REFERENCE
28
45*
53,54,97
113*
151*
193,194
205,207
269,270*
284*
288*
168
INFLUENT
CONCENTRATION, mg/l
BOD5
-
_
7100
12,900
-
230
260
36,000
8090
8090
8090
8090
13,600
1000
COD
9760
35,000-
58,000
15,800
19,400
2400-4500
360
500
48,000
13,000
13,000
13,000
13,000
19,300
1700
Y mgVSS
'rrtg- BOD5 or COD
BOD5 COD
0.35
0.42
0.4
0.49 0.34
0.29**
0.59
0.50
0.332
0.49
0.51
0.51
0.55
0.374
0.59 0.42
b.day'1
BOD,-
•> .
_
-
0.015
-
-
0.336
0.0025
0.009
0.018
0.006
0.002
0.015
0.40
u mgBOD, or COD
pwx, 3 v
mgVSS-day V 9'
COD BOD5 COD B005
0.084 - 0.28
0.025 - -
0.05 - 0.6
0.016 0.15 0.5 12.3
2.4 - 24
0.115 - 1.06
16 - 41.3
0.25 - 21,380
0.57 - 82
0.57 - 64
0.26 - 35
0.19 - 17
0.28 - 19.6
0.56 4.5 - 99
'1
COD T, °C
673 22-24
22-24
175 22-24
1800 5
1460 22-24
182 22-24
22-24
22-24
22-24
15
10
5
22-24
21-24
Domestic Wastewater,
Metcalf and
Eddy, 1979
0.4-0.8 0.35-0.45
0.04-0.075
0.05-0.10 1-8 4-11 25-100
15-70 22-24
'Nutrient adjusted, BOD5:N:P = 100:5:1
"Based on dehydrogenase activity rather than VSS measurement as viable organism concentration.
-------
TABLE 11. LANDFILLS WITH PILOT- OR FULL-SCALE AEROBIC LEACHATE TREATMENT FACILITIES
REFERENCE
SCALE
PROCESS*
PROCESS DESCRIPTION
LANDFILL
LOCATION
15 Full AL Lime neutralization as pretreatment
prior to biological treatment with
effluent discharge to surface water.
26 Full AL Lime addition for metal removal,
neutralization prior to biological
treatment with effluent discharge
to POTW.
113,114,115 Full Al- Facultative aerated lagoon with land
disposal of treated effluent.
157 Full AL.SP Series of four ponds, flow equali-
zation, aeration, and two stabiliza-
tion ponds with discharge to surface
water for effluent disposal.
166 Full SP Four ponds operated at very long
detention time followed by effluent
discharge to surface waters. Use of
aquatic plants to enhance treatment
performance.
187 Full AS.SP Aeration tank with clarifier
operated without solids recycle
followed by spray irrigation of
effluent. Leachate storage in
stablizatlon pond for winter.
228 Pilot AS Complete-mix aeration tank with
clarifier operated with solids
recycle.
231 Full AS.SP Chemical addition as pretreatment
prior to activated sludge or stabili-
zation pond treatment with effluent
discharge to surface water.
244 Full AL Series of five diffused aeration
lagoons and one settling lagoon
followed by spray irrigation of
effluent flow equalization.
245,246,247 Full AS Lime addition and ammonia stripping
248,256 and neutralization followed by
biological treatment operated on
no solids recycle basis for organic
substrate removal and nitrification.
Effluent disposal by spray irriga-
tion or surface water discharge.
Allegheny County,
Pennsylvania
(2 landfills)
North Hempstead,
New York
Jefferson County,
Missouri
West Germany
Barre, Massachusetts
England
West Germany
Pennsylvania
(2 landfills)
West Germany
Bucks County,
Pennsylvania
*AS = Activated Sludge
AL » Aerated Lagoon
SP = Stabilization Pond
series and parallel operations were fairly similar, with both systems
achieving 92 to 97% BOD5 removal at loading rates of 1.5 to 1.8 kg BOD5/m3-day
and 8G of 2 to 4 days. On a yearly basis, the series mode provided superior
nitrification; nitrification efficiencies for the parallel reactors decreased
from 95% at 15 to 29°C to 40$ at 0 to 12°C.
In other studies (Klingl, 1981), a higher-strength leachate was used to
provide a BOD^ loading of 6.3 kg/m3-day. Organic removal efficiency with this
loading was somewhat lower at 83 to 9^% BOD5 removal and 78 to 89% COD removal.
It was reported that process inhibition was attributable to NH3, although the
low retention time and high loading rate were probable contributors as well.
50
-------
TABLE 12. SUMMARY OF LEACHATE TREATMENT PERFORMANCE AND DESIGN PARAMETERS
FOR PILOT-SCALE AND FULL-SCALE ACTIVATED SLUDGE TREATMENT
FACILITIES
— REFERENCE
ITEM _
Treatment Scale
Influent Quality
BOD., mg/1
COD, mg/1
TOC, mg/1
BODc/COD
COD/TOC
TKN, mg/1
NH3-N, mg/1
BOD,-:N:P
Fe, mg/1
pH
Temperature, °C
Q, nwday
Pretreatment
Chemical addition
Flow equalization
Nutrient addition
NH3 stripping
Primary clarification
Treatment
Aeration ,
BODj- loading, kg/m -day
COD loading, kg/nH-day
MLVSS, g/1
F/M, BODc/MLVSS-day
F/M, COD/MLVSS-day
T, hours
0C, days
Air, m^/min
(187)
Full
1340
2460
_
0.54
_
_
168
100:8:-
10
-
12-18
150
No
1.3
2.5
-
24
1
-
(228)
Pilot
3580
4540
1710
0.79
2.7
-
-
100:5:0.5
-
-
6-7
1.17
No
No
Yes
No
No
0.30
0.39
4-5
0.16
0.20
144
12
-
Pilot
3580
4540
1710
0.79
2.7
.
_
100:5:0.5
.
_
10-15
1.17
No
No
Yes
No
No
0.30
0.39
4-5
0.16
0.20
144
12
-
U31)
Full
2500
.
-
-
90
50
_
750
6.0
0-25
662
-
No
No
No
No
-
-
-
_
-
i
Full
Sl-P*
3560
6480
-
0.55
-
290
290
100:5:1
3.6
7.6
0-24
79.5
Lime,H,P04,
H,SO.
t& 4
Yes
Yes
No
1.8
3.2
6-12
0.30-0.15
0.56-0.27
48
2
14.2
(245,246,247
Full
Sl-P*
5970
9870
-
0.60
-
-
740
100:5:1
1.9
7.6
20-24
37.9
Lime,H,PO.,
H,SO, J *
Y!S 4
Yes
Yes
No
1.5
2.5
6-12
0.25-0.12
0.42-0.20
96
4
14.2
,248,256)
Full
S3*
12,600
21 ,200
-
0.59
-
708
649
100:5:0.02
350
7.6
20-29
75.7
No
6.3
11
6-12
0.53-0.26
0.90-0.44
48
2
14.2
Full
S4*
12,600
21,200
-
0.59
-
708
649
100:5:0
350
7.6
20-29
75.7
No
6.3
11
6-12
0.53-0.
0.90-0.
48
2
14.2
.02
26
44
-------
TABLE 12 (Continued)
Ln
ho
Secondary Clarification
Overflow rate, m /m -day 2
T, hours
Posttreatment
Chemical addition
Sand filtration
Chlorlnatlon
Effluent Quality
BOD,-, mg/1
COD, mg/1
BODr removal , %
COD removal, %
TKN, mg/1
NH,-H, mg/1
NH,-N removal , %
FeJ, mg/1
Fe removal , %
pH
Sludge Characteristics
Solids, X
Volatile, %
SVI, ml/g
Effluent Disposal
48
No
1215
2280
9.3
7.3
164
2
_
.
-
-
-
-
Spray irrigation,
9.4 l/m2-day,
60% BODc removal ,
35% COD removal ,
60% NH3-N removal
0.7-1
24-40
No
220
380
94.0
91.6
_
_
_
_
-
-
-
<300
Surface
water
0.7-1
24-40
No
40
200
97.8
95.6
_
70
_
-
1.3
50
50
Surface
water
1.5
14
No No
Yes No
No Yes
120
940
96.7
85.5
102
80
72.0
3.0
17
7.6
-
-
80
Surface Surface
water
• 1.4
15
No
No
Yes
460
1090
92.2
89.0
-
6.3
99.1
0.7
62
7.6
-
-
80
water or spray
1.4
15
No
No
Yes
760
2260
94.0
89.3
153
76.4
76.4
1
99.7
10.2
-
-
-
irrigation
1.4
15
No
No
Yes
2150
4680
83.0
77.9
312
51.9
51.9
200
44
8.6
-
.
-
*S1-P: System 1 with aeration tanks in parallel
Sl-S: System 1 with aeration tanks in series
S3-P: System 3 with aeration tanks in parallel
S4-P: System 4 with aeration tanks, in parallel
-------
The English facility (Newton, 1979) did not perform well with regard to
either carbon or ammonia removal. The very low cell retention time (1 day)
probably did not allow sufficient time for effective substrate removal.
Aerated Lagoon—
The aerated lagoon has been the most commonly used process for leachate
treatment on full-scale. Treatment performance and design parameters for the
full-scale aerated lagoon treatment facilities reviewed in this study are
presented in Table 13. Although five facilities were reported, only three
could be evaluated since sufficient information was not available for two of
the facilities (Brownell, et al., 1982; Goeppner, 1975 a,b) Overall, the
aerated lagoon proved to be an effective means for leachate treatment in terms
of 8005, COD, and Fe removal. Detention times ranging from 7 to 135 days
provided 70 to 99% BOD5 removal and 70 to 95$ COD removal. Typically, 90%
BODcj removal was achieved along with 92 to 99% Fe removal.
Data on the treatment of various leachates which were characterized by
influent BOD^ concentration and the BOD^/COD ratio were also provided by
Stegmann (1981). It appears evident from these data (Table 13) that leachates
with a low BOD5/COD ratio (0.05-0.2) required very long detention times to
achieve substantial BOD^ removal. This might be attributed to the resistance
of humic and fulvic acid substances that result during organic substrate
assimilation which are less biodegradable than the original organic substrate
(Chian and DeWalle, 1977a,b).
Stabilization.Pond—
The stabilization pond has been used at four existing landfills reported
in the literature. A summary of the treatment performance and design
parameters for the full-scale stabilization ponds is given in Table 14. In
spite of its simplicity, the stabilization pond generally achieved
satisfactory treatment performance with 93 to 99$ 8005 removal and 90 to 99$
COD removal at T = 60 to 90 days. However, low BOD^ and COD removals were
reported by Klingl (1981) for low-strength leachates as characterized by low
influent 6005 and COD concentrations and low BOD^/COD ratios (0.06 - 0.08).
High Fe removal (91-99$) was achieved for T = 60 to 90 days. NH^-N removal
varied from 22 to 99$ removal for T = 43 to 90 days. BOD5, COD, NH^-N and Fe
removals improved as t was decreased.
Treatment and Disposal of Aerobic Process Solids
Solids treatment and disposal are essential aspects of all aerobic
biological treatment processes. Therefore, sludge solids characterization is
helpful in designing and evaluating the operation of sludge treatment units
and determining acceptable methods for final disposal. Seven parameters have
been used to characterize such solids as listed below along with their
intended uses.
53
-------
TABLE 13.
SUMMARY UF LEACHATE TREATMENT PERFORMANCE AND DESIGN PARAMETERS
FOR FULL-SCALE AERATED LAGOON FACILITIES.
REFERENCE
ITEM _
Influent Quality
BOD,, mg/1
COO, mg/1
TOC, mg/1
BOOc/COD
COD7TOC
TKN, mg/1
NH3-N, mg/1
BOD5:N:P
Fe, mg/1
pH
Temperature, °C
Q, m^/day
Pretreatment
Flow equalization
Lime addition
Settling
Neutralization
Nutrient addition
Preaeration
Treatment ,
BODc loading, kg/m -day
COD loading, kg/m3. day
i.days
Post-treatment
Settling
Chlorination
Chemical addition
Effluent Quality
BODc, mg/1 •
COD, mg/1
BOOc removal, %
COD removal, *
TKN, mg/1
NHVN, mg/1
NH',-N removal, %
Fe, mg/1
Fe remova 1 , %
PH
Effluent Disposal
(15)
120
-
.
-
.
-
10
100:8:-
60
6.8
10-25
355
No
Yes
t=2d
No
No
No
0.01
-
20
T=2d
Yes
No
10
_
92
70
-
-
_
1
98
7.5
Surface
for both
3000
-
.
.
-
-
30
100:1:-
120
5.6
10-25
45.4
No
Yes
T*2d
No
No
No
-
.
-
r=2d
No
No
920
-
70
.
.
-
.
10
92
7.4
water
(26)
10,000
14,000
-
0.71
-
700
600
100:5:
700
-
2-25
303
No
Yes
Yes
Yes
Yes
Yes
0.33
0.47
30
No
No
H202
-
-
-
.
-
-
-
-
-
-
POTW
(113-115)
800
1500
455
0.53
3.3
-
.
1
.
6.0
0-25
37.9
No
0.01
0.02
90
No
-
-
-
-
-
-
-
-
-
-
Ridge and furrow
land disposal,
rste: 4 71/m2-day
(157) (244)
5310 4500 3000 650
7800
2740
0.68 >0.4 0.4 0.2
2.8 -
270 ...
240 ...
100:5:0.4 ...
60 ...
6.8 ...
0-25 5-20 5-20 5-20
216 ...
No No No
T=2d
No
No
No
Yes
No
0.76 0.03 0.03 0.005
1.1 ...
7 135 120 120
No No No
r=5.3 hrs
No
No
50 25 25 25
415 -
99 >99 >99 96
95 -
100 ...
80 ...
66 -
0.2 -
>99
8.1 ...
Stabili- Spray irrigation for
zation four cases
pond
100
-
-
0.05
-
-
-
-
-
-
5-20
-
No-
0.001
-
90
No
25
-
75
-
-
-
-
-
-
-
all
54
-------
TABLE 14. SUMMARY CF LEACHATE TREATMENT PERFORMANCE
AND DESIGN PARAMETERS FOR FULL-SCALE
STABILIZATION POND FACILITIES
REFERENCE
ITEM -—______
Influent Quality
BOD,-, mg/1
COD, mg/1
TOC, mg/1
BOD.-/COD
COD/TOC
TKN, mg/1
NH,-N, mg/1
BOD,:N:P
Fe, mg/1
PH
Temperature, °C
Q, mj/day
Pretreatment
Chemical Addition
Biological Treat-
ment
Settling
Nutrient Addition
Treatment
BOD5 loading,
kg/m3-day
COD loading,
kg/m3-day
T, days
Post-treaunent
Effluent Quality
BO DC, mg/1
J
COD, mg/1
BOD,- removal, %
COD0 removal, %
TKN, mg/1
NH,-N, mg/1
NK,-N removal, %
Fe, fflg/1
Fe removal , %
PH
Effluent Disposal
(157)
28
370
92
0.08
4.0
92
81
100:290:5
-
8.4
18-23
77.8
No
Yes
Yes
No
<0.01
<0.01
63
No
21
330
25
11
76
63
22
-
-
8.5
Stab.
Pond
21
330
74
0.06
4.5
76
63
100:300:10
-
8.5
18-23
77.8
No
Yes
Yes
No
<0.01
<0.01
44
No
13
160
38
52
20
12
81
-
-
8.3
Surface
Water
(166)
21,100
35,700
-
0.59
_
-
440
100:2:-
1400
5.2
0-25
4
No
0.70;0.35;
0.23
1.2;0.60;
0.40
30; 60; 90
No
4650 ;220;
10
9500 ;400;
120
77;99;>99
73;99;>99
-
130;70;3.5
70; 84; 99
320;120;1.0
77;91;>99
6.5;6.8;7.3
(187)
1340
2460
-
0.54
.
-
168
100:8:-
-
-
0-18
150
No
0.01
0.03
90
No
100
-
93
-
-
-
-
-
-
-
(230)
-
2500
-
-
.
90
50
-
750
6.0
0-25
549
Yes
No
Yes
No
-
-
-
No
-
-
-
-
-
-
-
-
-
-
Surface Water Surface Surface
Water
Water
- Data not given
55
-------
Test Use
% Solids Design of sedimentation units; opera-
tional parameter for sludge settleability.
% MLVSS/MLSS Design of sludge digestion units.
Specific resistance Design of sludge dewatering units.
Filter yield Design of sludge dewatering units;
quantity for disposal.
Settling velocity Design of sedimentation units.
Metal content Determine acceptance for ultimate disposal.
Sludge Volume Operational parameter to determine activated
Index (SVI) sludge settleability in sedimentation units.
Results of solids characterization tests are presented and compared to
typical values reported for domestic wastewater activated sludge in Table 15.
Percent solids for leachate-derived sludges (1.1-5.0?) was determined to be
slightly greater than the typical value for domestic wastewater (0.5-1.5?).
This was possibly attributable to higher inorganic content in the leachate
sludges," especially in terms of iron and calcium. Moreover, the percent
volatility expressed as % MLVSS/MLSS for the leachate sludge was slightly
lower than for domestic wastewater sludge.
A significant difference was also noted between specific resistance
values of typical domestic wastewater sludges and those reported for
leachate-derived sludges. The specific resistance of leachate sludge without
chemical conditioning (10^ m/kg) was reported as one to two orders of
magnitude less than the wastewater sludge values (10^3-io^ m/kg) without
chemical conditioning. However, when the sludge was preconditioned with a
chemical or polymer, specific resistance for the leachate sludge was superior
to the typical wastewater range; a difference of two to four orders of
magnitude in specific resistance existed between the two sludges. The
leachate activated sludge exhibited very good dewatering properties as
indicated by the reported specific resistance values.
Filter yields, expressed as kg/m^-hr, were similar between the two cases;
the leachate sludge filter yield varied from 2.2 to 28 and the domestic
wastewater activated sludge varied from 2.4 to 20 with chemical conditioning.
The higher values indicated for the leachate sludge were induced by high
chemical additions for conditioning. Settling velocities for the two types of
sludges were also fairly similar, although the leachate involved a somewhat
thicker suspension.
Iron (Fe) and zinc (Zn) were found to be present in high concentrations
(75,000 mg Fe/kg SS and 4000 mg Zn/kg SS) in leachate sludges. Cadmium (Cd),
chromium (Cr), lead (Pb), and manganese (Mn) levels in the leachate sludge
were reported to be similar to those found in sewage sludges.
56
-------
TABLE 15. SUMMARY OF SLUDGE CHARACTERISTICS FOR AEROBIC LEACHATE TREATMENT PROCESSES
REFERENCE
45
53,54,97
118,119
151
143
^60,261
288-291
Typical
MLVSS
PROCESS* SOLIDS, %** HLSS ,%
AL
AL
AL
AL
AL
AL 2-4
AS - 66-73
AS - 47-64
AS - 41-51
AS 1.1-5.0 22-64
(2-D
AS - 59-63
AS - 53-67
AS 0.5-1.5 50-80
for Domestic
Wastewater***
- Data
* AS =
not given
Activated Sludge
SPECIFIC FILTER- SETTLING
RESISTANCE, m/kg YIELD, kg/m-hr VELOCITY, cm/sec
1.4 x 1012 9 P = 2.2 @ -47 cm Hg
37 era Hg ,,
0.07-1.3 x 10 3.4-28 9 -47 cm Hg
w/FeCl, ,-
0.05-1T4 x 10^ 2.2-15 9 -47 cm Hg
w/Lirae ,,
0.06-0.5 x 10 5.4-12 9 -47 cm Hg
w/Polymer .-
0.2-0.4 x 10 f 4.9-6.8 9 -47 cm Hg
w/Polymer
0.001-0.02 9
20-40 g/8.
-
-
-
0.85-9.6 x 1012
_ -
.
4.8 x lo!]- 2.4-20 with chemical 0.005-0.13 9
2.8 x 1014 conditioning 1-14 g/i
nd ' not detected
( ) = mean value
mg metal
METAL CONTENT IN WET SLUDGE, kg SS
Cd Cr Fe Pb Mn Zn
- _ -
- - ...
.
. - - -
- - - - -
- - - -
.
.
.
. - - - - -
5.3-7.6 47-168 77,000- 17-127 2800 4400-
89,000 5200
-
nd-1100 22- <1000- 80- 100- 51-
(87) 30,000 40,000 26,000 8800 28,360
(1800) (10,000) (1900) (1200) (3500)
AL = Aerated Lagoon
** After 30 rain to 1 hour settling
*** References: Dick and Ewing (1967); Javaheri and D1ck (1969); Karr (1975); Coackley (1960); Gale (1968); Dahlstrom and Cornell (1958);
FPA H976); Metcalf 4 Eddy (1979)
-------
The Sludge Volume Index (SVI) is commonly determined to evaluate sludge
settleability, although its transferability between studies has definite
recognized limitations. The test was originally designed for use in
evaluating operational problems during settling of activated sludge. Despite
its limitations, the SVI was examined for its potential as a relative
indicator of sludge settleability among the data that were presented in the
literature. Since SVI is a function of the suspended solids concentration,
the data were segregated on the ba^is of MLSS concentrations. The SVI was
then plotted versus 9G to provide a relative indication of sludge
settleability as shown in Figure 17. Overall, the SVI was frequently <75,
possibly indicative of good sludge settleability.
150 _
125
100
oo
r-4
a
50
25
LEGEND
3 MLSS <5000 rag/1
(References 45,143,151,272)
Q MLSS 5000 -10,000 mg/1
(Reforencea 51,119,143,151)
A MLSS > 10,000 tng/1
(Reference 45)
Open symbols: Activated sludge
Shaded symbols: Aerated lagoon
— Q
a
a
-o o
a
a
B
I
10 20 30 ' 60
Mean Cell Residence Time (9 ), days
90
Figure 17.
Relationship Between Sludge Volume Index
and Mean Cell Residence Times for Aerobic
Biological Treatment Studies
58
-------
Although variations in sludge characteristics hamper the use of SVI as a
universally accepted criterion, it is generally accepted that a SVI >100
reflects relatively poor settleability, whereas SVI <100 reflects relatively
good settleability. On this basis, poor, good and very good sludge
settleabilities were reported in the literature which indicated
correspondingly variable sludge settling characteristics. In addition,
deflocculation was reported to have occurred regardless of the degree of
settleability. In fact, deflocculation sometimes occurred in sludges that
were described as portraying very good settleability after the sludge had
settled (Johansen, 1975). Pinpoint floe and sludge bulking were also
identified for activated sludge processes treating leachate (Boyle and Ham,
1972, 1974; Graham and Mavinic, 1979; Graham, 1981).
ANAEROBIC BIOLOGICAL PROCESSES
Anaerobic biological treatment methods can provide a number of advantages
over the traditional aerobic processes reviewed. In particular, an energy
surplus may be available from the production of methane. Moreover, anaerobic
cell yields are lower, resulting in lower sludge production and associated
handling costs. Accordingly, the variables of interest in evaluating the
feasibility of anaerobic treatment of leachate include methane production
rates as well as the variety of indices used in describing aerobic treatment
process performance.
Three general types of anaerobic treatment processes have been evaluated
for the treatment of landfill leachates. These include external treatment in
suspended-growth (SG) or attached-growth (AG) reactors, and in situ treatment
using leachate collection and recycle back through the landfill. Little
information was available beyond bench-scale for the external treatment
systems. Therefore, these are discussed first, followed by a review of
leachate recycle studies on all scales.
Bench-Scale Anaerobic Processes
The external anaerobic treatment strategies (SG, AG) studied on
bench-scale (and one pilot-scale study) include applications of both
completely-mixed and plug-flow reactors as summarized in Table 16. The
experimental data associated with these studies are summarized in Appendix
Table A-9 and utilized in the ensuing discussions of process variables.
Effect of Mean Cell Residence Time Oc)--
The data for bench-scale anaerobic treatment of leachates (Appendix Table
A-9) were segregated as before on the basis of influent strength and
biodegradability ratios. Limited 6005 data were available, therefore, only
two influent categories (medium- and high-strength) were used in describing
the effects of 8G. Medium- and high-strength influents are described as
having 1,000 to 5,000 mg/1 6005 or 1,000 to 10,000 mg/1 COD and >5,000 mg/1
8005 or >10,000 mg/1 COD, respectively. Leachates which received nutrient
amendments are also distinguished.
The relationship between 9C and organic removals is illustrated in
Figures 18 and 19 for 6005 and COD, respectively. The data presented in these
figures are from mesophilic (33-37°C) studies; studies at lower temperatures
59
-------
TABLE 16. BENCH-SCALE ANAEROBIC BIOLOGICAL TREATMENT OF LEACHATE
REFERENCE PROCESS
PROCESS DESCRIPTION
RESEARCH OBJECTIVE(S)
LEACHATE
SOURCE*
14
Suspended Plug flow, continuous upflow
growth reactor. **
19,20,147 Suspended
growth
33,176,217 Suspended
growth
Plug flow, daily fill and
draw reactor operation.
Complete-mix, continuous
flow reactor.
44,45,46 Attached Complete-mix, continuous
growth upflow filter containing
plastic media.
b8,70,73 Attached Complete-mix, continuous
growth upflow filter containing
plastic media.
Effect of temperature on COO Landfill
and metal removal efficiencies
and gas production .
Effect of 0r and BOD5 and COD Landfill
loading on 8005 and COO removal
and gas production.
Effect of 8005 and COO loading Lysimeter
on BOD; and COO removal and gas
production-, determine kinetic
parameters; extent of heavy
metal removal .
Effect of pH adjustment, sludge Lysimeter
seeding, shock loading and 0C on
COD and metal removal efficiencies
and gas production.
Determine operating variable Landfill
that controls heavy metal
remova1 eff i c i ency.
98,220 Attached Plug flow, continuous upflow
growth; filter containing crushed
Suspended limestone as contact media;
growth complete-mix, hourly fill
and draw reactor operation.
Effect of temperature, pH
adjustment, nutrient addition,
and COO loading on COO and
TOC removal efficiencies;
determine kinetic parameters.
Landfi11
135,136 Suspended Complete-mix continuous
growth flow reactor.
143 Suspended Plug flow, upflow filter
growth containing crushed lime-
stone as surface contact
media, operated fill and
draw and continuous flow
mode.
Effect of Gc on 8005 and Landfill
COD removal efficiencies
and gas production; effect
of sodium inhibition.
Effect of BOD5 and COD Landfill
loading, temperature, and
effluent recirculatlon on
BODe, COD and metal removal
efficiencies and gas production.
151,205,
206,207
223
30
237
Suspended
growth
Attached
growth
Suspended
growth
Attached
growth
Complete-mix, continuous
flow reactor.
Plug Flow, upflow fiUer
containing rock media.
Complete-mix, semi-
continuous flow reactor.
Plug flow, upflow filter
containing plastic media.
Effect of 9C on BODj and COO
removal efficiencies; deter-
mine kinetic parameters.
Effect of o on organics
removals ana gas production.
Effect of feed concentration
on organics removal .
Effect of HRT on organics,
metal removals and gas
production.
Landfill ,
lysimeter
Landfill
Landfill
Landfill
*A11 leachate sources are characteristic of municipal solid waste landfills.
"Pilot-scale study.
60
-------
5000
D
UOOO
3000
2500
2000
1500
1000
500
a
El
_L_
a
§
5 10 15 20
Mean Cell Residence Time (9C), days
LEGEND
D Medium Influent BOD5: (1000-5000 mg/1)
(References 136,151,207)
A High Influent BOD5: (>5000 mg/1)
(Reference 33)
Nutrient Adjusted!
BOD5:N:P.100:5:1
25
100 _
10 15 20
Mean Cell Residence Time («c), days
Figure 18. Relationship Between Mean Cell Residence Time and
Removal for Bench-Scale Anaerobic Treatment Studies
-------
9000
8000
TOGO
6000
5000
rH
g UOOO
I
u
3000
2000
1000
I
I
5 10 15 20
Mean Cell Residence Time («c), days
LEGEND
-) Medium Influent COD: 1000-10,000 mg/1
(References 136,151,207)
& High Influent COD: >10,000 mg/1
(References 11.33,98)
. Nutrient Adjusted:
BOD5:N:P-100:5:1
Open symbols: Suspended growth
Shaded symbols: Attached growth
100 [-
25
P
8
5 10 15 20
Mean Cell Residence Time (8C), days
Figure 19. Relationship Between Mean Cell Residence Time and COD Removal
for Bench-Scale Anaerobic Treatment Studies
-------
also yielded similarly favorable results as summarized in Appendix Table A-9.
In general, 6C in excess of 10 days provided effluent 8005 and COD
concentrations below 500 mg/1 and 750 mg/1, respectively. These effluent
levels were representative of 85 to 98/6 removal efficiencies.
The data were additionally segregated according to the previously used
biodegradability ratios (BOD5/COD and COD/TOG) as illustrated in Figure 20.
Scrutiny of this figure confirmed the information already provided in Figure
19 in that greater than a 10 day 9C allowed for better than 90% removal of
influent COD.
Organic Loading Effects —
The relationships of effluent organics (8005, COD) and organic removals
to organic loading rate are illustrated for the data of Appendix Table A-10 in
Figures 21 and 22. Process performance deteriorated rapidly beyond 8005
loadings of 1 kg/m3-day or COD loadings of 2 kg/m3-day. Treatment of
high-strength leachates resulted in stronger effluents at high loading rates
(1 kg BOD5/m3-day) than did medium-strength influents. However, higher
percentage removals were recorded for the high-strength leachates at high
loading rates than for the medium-strength leachates.
Gas production data are commonly used as an indication of process
performance and are also of economic interest. Organic loadings were used as
a basis for reviewing the quantitative significance of gas production data
(Appendix Table A-1 1 ) during anaerobic treatment. The relationships of
interest are illustrated in Figure 23 in terms of the volume of gas produced
per kg of 8005 or COD destroyed at different organic loading rates.
Considering the following redox stoichiometry at 35°C, the theoretical methane
yield on a COD basis is 380 I/kg COD:
CHij + 202 - > C02 + 2H20
64 g 02/mole CHij, or
2.6 g 02/Hter CHij
Taking into consideration that gases produced will typically be on the order
of 60 to 7Q% methane, the theoretical total gas yield for COD utilized is
550 to 650 I/kg COD. Furthermore, considering that the BOD5/COD ratio for the
anaerobic studies was typically 0.^5 to 0.78, the theoretical gas yield on a
8005 basis would be on the order of 900 to 1000 I/kg 8005. These values are
indicated by the dashed lines on Figure 23, which serve to illustrate the
effects of increasing the loading rates beyond 5 kg COD/m3-day or 2 kg
In comparison with the earlier plots of organic removal versus organic
loading rate, the data of these figures seem to suggest that in the range of
2 to 5 kg COD/m3-day, the gas production remains high, yet organics cannot be
assimilated rapidly enough to avoid escaping into the effluent. Loading
increases beyond 5 kg COD/m3-day are apparently detrimental to the anaerobic
methane-producing bacteria, as a result of substrate and/or chemical
intermediate (volatile acids) induced inhibitions illustrated by decreasing
gas production rates.
63
-------
100 _
So
a
3
20
I
Low Strength: BOD5/COD<0.5 (0.15-0.17)
(References 98,151)
Q Medium Strength: 0.50.75
(Reference 151)
• Nutrient Adjusted:
BOD5:M:P-100:5:1
Open symbols: Suspended growth
Shaded symbols: Attached growth
_L
5 10 15
Mean Cell Residence Time ( 8, ) ,
20
100 ,—
so
60
a
8
20
25
90*
Medium Strength: 2.0
-------
s
M
5000
Uooo
3000
2500 _
2000 _
1500 _
1000
500
0 Q
LEGEND
D Medium Influent BOD5: 1000-50OO mg/1
(References 136,151,207)
A High Influent BOD: >5000 mg/1
{Reference 33)
• Nutrient Adjusted:
BOD5:N:P-100:5:1
Open symbols: Suspended browth
Shaded symbols: Attached growth
100
80
60
ItO
20
- El
90%
I I I
J
2 3
BODs Loading, Kg/m3-day
10 20 30 1*0
'10 20 30 Uo
BOD5 Loading, Kg/m3.day
Figure 21. Relationship Between Organic Loading Rate and BOD5 Removal
for Bench-Scale Anaerobic Treatment Studies
-------
C^
io;ooo
8,000
6,000
«
5,000
It, 000
a
3,000
B
w
2,000
1,000
0
-
_
Q Q
fe.
A
Q
Q
-
Q
E*
QrjR
3Q I 1 1 A 1 1 1
0 2 It 6 20 ItO 60
LEGEND
Q Medium Influent COD: 1000-10,000 mg/1
(References 136,151,207)
A High Influent COD: >10,000 rag/1
(References 14,33,96)
. Nutrient Adjusted:
BOD6;N:P-100:5:1
100
I
a
8
80
f
60 - Q
>»0 _
20 -
1
1
COD Loading, Kg/m3-day
2 It
COD Loading,
•4r
20 ItO 60
Figure 22. Relationship Between Organic Loading Rate and COD Removal
for Bench-Scale Anaerobic Treatment Processes
-------
1£UU
>• 1000
h
u
1
a
* 800
1
§ 600
U
•g
3 400
200
0
a
--——— — -- -
A
L° A
a
e o
LEGEND
D Medium Influent BODc: 1000-5000 mg/1
_ (References 136,151)
A High Influent BOD5: >5000 mg/1
(Reference 33)
• Nutrient Adjusted:
BOD5:N:P-100:5:1
-
a o
1 1 1 A I 1 1 d
0 1 2 3 '10 20 30 40
%
•H
4J
I
cu
3
1500
1000
800
600
400
200
LEGEND
p Medium Influent COD: 1000-10.000 mg/1
(References 136,153)
A High Influent COD: >10,000 mg/1
(References 11,33,98)
. Nutrient Adjusted:
BOD5:l|:p,100:5:1
20
40
60
BOD5 Loading, Kg/m' .day
COD Loading, Kg/m3.day
Figure 23. Relationship Between Gas Production and 8005 and COD Loading
Rates for Bench-Scale Anaerobic Treatment Studies
-------
Temperature Effects—
From inspection of the data presented in Appendix Table A-9, successful
anaerobjc treatment was indicated at temperatures lower than the mesophilic
range. Although studies on anaerobic treatment of leachate have been
performed at temperatures ranging from 11° to 27°C, the most successful of
these have been in the 23° to 27°C range as illustrated in Figure 24 for 8005
and COD removals.
The effects of temperature are further illustrated in Figure 25 using gas
production. The figure clearly shows an increase in gas production at
33° to 37°C over that at 22° to 27°C. If sufficient retention time is
provided (10-12 days), however, greater than 90? 6005 and COD removals can be
realized with the lower temperature range. Moreover, the figures do not show
a distinct difference between attached- or suspended-growth systems. (The
numbers indicated next to the data points are their respective organic loading
rates in kg BOD5/m3-day.)
Metals Removals—
A summary of metal removal data available from the literature for
anaerobic treatment processes is presented in Table 17 and Appendix Tables
A-12 and A-13- Except for iron and zinc, effluent heavy metal concentrations
were generally on the order of 1 mg/1 or less. As with the aerobic processes,
zinc, iron, and chromium removals were above 90?. Copper, lead, cadmium, and
nickel removals were on the order of 50 to 90?, although one study (Johansen,
1975) indicated no removal of cadmium and lead.
The alkali and alkaline earth metals were largely unaffected by anaerobic
treatment processes with calcium being removed most efficiently, i.e., at 31?.
Magnesium, potassium, and sodium removals were typically below 10? as
indicated in Table 17 and Appendix Table A-13.
TABLE 17. SUMMARY OF HEAVY METAL AND ALKALI AND ALKALINE EARTH METAL
REMOVAL DATA FOR BENCH-SCALE ANAEROBICTREATMENT PROCESSES
Heavy Metals
Cd Cr Cu Fe Pb Hn HI In
Influent
Concentration Range, 0.03-0.1 0.22-1.7 0.03-5.6 245-810 0.12-1.4 6-18 0.19-12 5-15
mg/1
Removal Range, % 0-99 0-90 38-88 80-99 0-84 69-92 10-86 80-99
Average Removal, % 14 73 60 95 13 81 68 96
Alkali and Alkaline Earth Hetals
Ca MJL K Na
Influent
Concentration Range, mg/1 315-1330 70-120 347-530 313-530
Removal Range, * 30-31 7-10 0-6 0-4
Average Removal, * 31 9 3 2
68
-------
100
J.UU
75
H
0
50
eg
tn
Q
§
25
0
(
0.2-1.0|* tfj Q.36.,.8
90* cSL
LEGEND
O Medium Influent BOD;: 1000-5000 mg/1 T5
— (References 19,1*3)
A High Influent BOD;: >5000 mg/1
(References 19,113)
X
Open symbols: Suspended growth ,-T
Shaded symbols: Attached growth > ...
_ Values: BODc loading, Kg/m->-day g
T fl "
/ /" ' i
_ «0.6 / 25
•i.a /
A 0.9U
0 9ft
t | A ' | „
) 10 20 30 C
Temperature, °C
0.3-5.3lAl AI
on< J _B_ffl3L
LEGEND . 0.65
- S b.9
Q Medium Influent COD: 1000-10,000 mg/1
(References 19,113)
A High Influent COD: >10,000 rag/1
(References 11,18,15,98,113
Values: COD loading, Kg/n3. day
B2.U
/ i
/ 1
• 0.3
•1.6 1 ?
i , i-5 i
1 1 A 1
) 10 20 30
Temperature, °C
Figure 24. Relationship Between Temperature and Organics Removal
for Bench—Scale Anaerobic Treatment of Leachate
1000
800
600
400
200
LEGEND.
O Medium Influent BOD;: 1000-5000 mg/1
(References 19,136,151)
A High Influent BOD;: >5000 rag/L
(References 19,113) A
. Nutrient Adjusted: .
BOD;:N:P-100:5:1 / TJ
Open symbols: Suspended growth Q
Shaded symbols: Attached growth
BOD5 Loading
1
1400
1200
^
800
600
200
LEGEND
Q Medium Influent COD: 1000-10,000 mg/1
(References 19,136,151)
AHlgh Influent COD: >10,000 mg/1
(References 11,19,33.15,98)
. Nutrient Adjusted:
BOD;:N:P-100:5:1 / £
Open symbols: Suspended growth
Shaded symbols: Attached growth
Decreasing
COD Loading
10 20 30
Temperature, °C
40
10 20 30 40
Temperature, °C
Figure 25. Relationship Between Temperature and Gas Production
by Bench-Scale Anaerobic Treatment of Leachate
69
-------
Anaerobic Treatment Kinetic Parameters—
The microbial dynamics of mixed reactor anaerobic processes can be
described using a combination of Monod kinetics, cell yield, and mass balance
concepts in the same fashion as for aerobic processes. Although limited data
were available for the treatment of leachates, a summary of the parameters
reported is presented in Table 18. These data compare fairly well with the
kinetic data also presented in Table 18 for the conversion of acetic acid (a
common leachate constituent). However, cell yields were somewhat higher for
leachate treatment.
TABLE 18. SUMMARY OF MONOD KINETIC PARAMETERS FOR THE ANAEROBIC LEACHATE TREATMENT PROCESS
REFERENCE
33
98
151, 205,
206
117*
INFLUENT
CONCENTRATION, mg/1
(B005) (COD)
13,000 26,000
12,900
3,700 6,000
1 ,600-
2,100
Y mgVSS
' mgBODc or COD u
3 D,
(BOD5) (COD) (B005)
0.1 - 0.006
0.33
0.25** 0.14** 0.175
0.04-
0.07
(T=20°C)
mgBODj or
day"1 max'mgVSS day
(COD) (BOD5)
5.9
0.17
0.127 1.0
0.03-
0.05
(T*20°C)
(COO)
-
1.4
0.5
0.31-
0.38
Ks, mg/1
(BOD5) (COD)
4020
633
232 300
13-165
t*Nutrient adjusted fatty acid wastewater; B005:N:P=100:5:1
**Based on dehydrogenase activity rather than VSS measurement as viable organism concentration
-Data not given
T = 34-37°C unless otherwise indicated
Anaerobic Process Sludge Characteristics—
Lower cell yields are generally exhibited by anaerobic processes when
compared to aerobic processes, although this distinction is not exceedingly
clear from a comparison of the yields reported in Tables 10 and 18. Limited
sludge characterization performed on sludges resulting from the anaerobic
treatment of leachate was available. However, some information on sludge
solids volatility, percent solids, and metal content is summarized in Table 19.
Scrutiny of this information indicates an average solids volatility on the
order of 40£ for solids contents of 2 to 7% (typically 4-5?). Iron and zinc
were the most prevalent metals, existing in g/kg solids concentrations;
calcium, chromium, copper, and lead were also occasionally found in high
concentrations. No data on specific resistance, settling velocities, or
sludge volume index (SVI) were located in the literature.
70
-------
TABLE 19. SUMMARY OF SLUDGE CHARACTERISTICS FOR THE ANAEROBIC LEACHATE TREATMENT PROCESS
REFERENCE
14
33,217**
143
45,46,73
Average
REACTOR* VOLATILE, %
PFR-SG
PFR-SG
PFR-SG
PFR-SG
PFR-SG
CSTR-SG
CSTR-SG
PFR-AG
PFR-AG
PFR-AG
PFR-AG
CSTR-AG
-
39
.
. i
_
-
.
-
36
37
36
51
38
40
SOLIDS, *
.
.
_
-
.
-
6.9
5.4
7.2
0.95
3.9
5.0
Cd Ca
5.1
_
6
16
6
0.66 7600
<0.7 4100
40
40
40
700
.
100
Cr
76
_
24
64
109
4.6
1.1
300
300
300
5800
_
900
METAL
Cu
75
.
192
192
216
4.0
1.8
900
600
1100
4100
_
900
mg metal
CONTENT IN MET SLUDGE, kg SS
Fe
" o
92x10,
43x10,
61x10^
77xlOJ
70
5230
300
300
300
5000
_
35x1 O3
Pb
70
.
264
264
312
19
3.6
100
100
100
2100
_
400
Mg Mn N1
81
140
64
112
114
390 321 7.2
317 114 4.1
...
.
...
.
...
100
K Na Zn
4300
2900
2700
3500
3150
625 750 2330
1290 588 1100
2500
5000
4100 ,
16xlOJ
. .
4900
COMMENTS
T=20°C
T=33°C
T=30°C, Pilot
T»30"C, Pilot
T=30°C, Pilot
T=34°C
T=34°C
T*23°C
T=23°C
T=23°C
T=23"C
T=23"C
p=1.026 g/cm;
Scale
Scale
Scale
|
- Data not given
* PFR-SG * Plug flow reactor suspended growth
CSTR-SG « Continuously-stirred tank reactor suspended growth
PFR-AG * Plug flow reactor-attached growth
** Dry sludge (centrlfuged)
-------
In situ Anaerobic Leachate Recycle Treatment
The collection and recycle of leachate back onto or into a landfill
represents an in situ method of leachate treatment as opposed to the other
biological processes previously reviewed. The treatment mode involved in this
approach is primarily anaerobic, although aerobic conditions at the beginning
and formation of humic substances during the final phases of a landfill's
"life" may be important with regard to organic conversion and the possible
re-mobilization of heavy metals, respectively. Moreover, the practice of
recycling leachate serves to improve the homogeneity of the biochemical
environment needed for anaerobic waste degradation, and may, thereby,
effectively shorten the time normally required for waste "stabilization" by as
much as 80 to 90% (Pohland, 1975, 1980). Current evidence also suggests that
the costs of leachate recycle treatment may be as much as 25% of the costs of
corresponding separate treatment (Pohland, 1979).
Pilot-Scale Leachate Recycle —
A number of pilot-scale investigations on the application of leachate
recycle have been performed. The test cells utilized and research objectives
associated with these studies are presented in Table 20. Operating variables
such as moisture content, pH adjustment, nutrients, microbial seed, and the
use of recycle have been reported as indicated in Table 21 . Of these
variables, the use of recycle and buffers have emerged as most important in
accelerating the onset of anaerobic waste degradation and in maximizing the
rate, consistency and quality of gases produced.
While recycle and buffer addition served to significantly shorten the
stabilization period, the effluent concentrations ultimately obtained by
comparative cells utilizing nutrients and/or microbial seedings, but without
recycle, were very similar. The effluents ultimately obtained were also very
similar in character to those obtained from anaerobic treatment processes,
e.g., BOD, -100 mg/1; COD, -300 to 500 mg/1; TKN, -100 to 300 mg/1; and, Fe,
mg/1.
In general, recycling of leachate promoted the development of in situ
biological, physical and chemical mechanisms responsible for waste
stabilization and/or leachate treatment. Biological assimilation of the
organic substrate by anaerobic microbial processes resulted in residual 6005
and COD concentrations of 30 to 500 mg/1 and 70 to 800 mg/1, respectively
(Table 21). Moreover, as microbial degradation progressed, the nature of
organic substrates in leachates became more refractory, as indicated by the
low BOD5/COD and COD/TOC ratios of 0.15 to 0.4 and 0.9 to 1.9, respectively.
TKN removal by leachate recycle effective with residual concentration of -50
to 100 mg/1 being typically achieved in long-term leachate recycle studies.
The pH of recycled leachate eventually increased to a range of 6.5 to 7.0 as a
result of the volatile fatty acids assimilation during the biodegradation
process.
The removal of heavy metals, represented by Fe and Zn in Table 21 , was
also effective. Residual concentrations of 40 mg/1 Fe and 4.0 mg/1 Zn were
commonly reported for the recycled leachate. The efficient removal of heavy
metals was attributed to chemical complexation by inorganic and organic
ligands which were found to be abundant in leachate and were able to form
metal-ligand precipitates. Sulfides were also determined to be a significant
72
-------
TABLE 20. PILOT-SCALE RESEARCH PERFORMED ON LEACHATE TREATMENT BY LEACHATE RECYCLE
REFERENCE
TEST UNIT
PROCESS DESCRIPTION
RESEARCH OBJECTIVE(S)
LEACHATE SOURCE
16 3m high Six columns with different
column waste mixtures, organic
lysimeter and inorganic wastes.
82-84,167 15m square Five test cells; control
by 3m high (no recycle), high initial
test cell moisture content, continu-
ous flow through of water.
leachate recycle, and
biological sludge seeding
with high initial moisture.
8,22,171,177, 3m high Four columns: control (no
201-207 column recycle), recycle, recycle
lysimeter with pH control at neutral
pH, and recycle with pH
control at neutral pH with
biological sludge seeding.
208,211 5m square Two cells; one sealed to
by 3m high prevent evaporation, other
test cell open to atmosphere to
allow for evaporation.
Both received equivalent
amount of water from rain-
fall.
210,212 3m high Four columns: control
column (municipal solid waste
lysimeter only) and three with
different quantities of
plating wastes mixed with
municipal solid waste.
Determine treatability of
leachate from pulp and paper
mill wastes through recycle;
evaluate organic and metal
removal and gas production.
Determine feasibility of
leaohate recycle for refuse
stabilization; effect of once
through moisture; effect of
biological sludge seeding.
Effect of pH control and
biological sludge seeding on
organic stabilization of waste.
Pulp and paper mill
waste.
Municipal solid waste.
Municipal solid waste.
Effect of evaporation on
refuse stabilization by
recycle. Evaluate organic
removal and gas production.
Determine removal mecha-
nisms of metal ions by
studying chemical activity
and chemical complexation.
Municipal solid waste.
Municipal solid waste
with metal plating
wastes.
-------
TABLE 20 (Continued)
280
1.8m high, Sixteen cells; combination
0.9m dia. of recycle, buffers,
teat cells nutrient additions to
leachates.
Determine the effects of
moisture, recycle, pH, and
nutrients on gas production
and leachate quality.
Municipal solid waste.
57
-P-
57
221
1.5m by 1.5m
square test
cells
600m3 test
fields
15mx10mx'Jm
1,6m deep by
5m2 area test
cells
Four cells; recycle of
leachate plus annual rain-
fall, no recycle, recycle
of half the annual rain-
fall, and, presaturation
followed by recycle of half
the annual rainfall.
Three fields filled with
compacted wastes; one
sealed against evaporation
and recycled, one with
recycle and no seal, one
without recycle.
Three test cells; simu-
lated annual rainfall
applied to each; one with
leachate recycle, one
with recycle of aerated
leachate, one without
recycle.
Determine the effects of Municipal solid waste.
moisture content and leachate
recycle on gas production and
leachate quality.
Determine the effects of
moisture content and leachate
recycle on gas production and
leachate quality.
Determine effects of leachate
recycle on gas production and
leachate quality; effects of
leachate aeration and phos-
phorous addition on ^n situ
biodegradation.
Municipal solid waste.
Municipal solid waste.
-------
TABLE 21. SUMMARY OF TEST VARIABLES. LEACHATE CHARACTER, AND GAS RESULTS FOR THE PILOT-SCALE LEACHATE RECYCLE STUDIES
TEST VARIABLES*
REFERENCE C F M N pH R S
8<:-84, X
167 X
X
X
X X
8,22,174, X
177,204-207 X
X X
XXX
208,211 (open cell) X
(sealed cell) X
266,268 X
X
X X
X X
XXX
57 ¥ X
' X
X
X X
280 X
X X
X
X X
221 X
X
X* X
RECYCLE
Sh FREQUENCY
Daily
.
.
-
Weekly
then
daily
Daily
X Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
TEST
PERIOD,
days
1440
1440
1440
1440
1063
1063
747
747
492
492
514
368
514
514
514
400
400
400
400
720
720
720
720
900
900
900
LEACHATE CHARACTER AT END
BOD5
40,000
30,000
3000
400
30,000
2000
30
35
40
90
70
8000
120
350
200
200
36,000
38,300
39,700
35,000
-
-
_
33
20
COD
50,000
50,000
5000
1500
50,000
3500
70
240
170
350
300
10,000
150
500
350
350
61,290
62,690
66,310
58,330
12,000
16,00
36,000
26,000
600
618
BOD5/COD
0.8
0.6
0.6
0.3
0.6
0.6
0.4
0.15
0.2
0.3
0.2
0.8
0.8
0.7
0.6
0.6
0.6
0.6
0.5
0.6
-
-;
COD/TOC
.
.
.
.
-
2.0
1.8
1.0
1.3
1.0
0.9
2.5
1.7
1.9
3.0
3.0
-
.
-
2.5
2.4
2.1
2.2
3.0
3.0
OF RECYCLE PERIOD**
TKN
500
1000
100
200
1000
11
2.0
8.5
1.4
20
20
„
50
20
36
330
"
-
.
-
250
170
825
875
136
50
Fe
1200
300
200
50
800
450
4
3
9
39
29
_
7
3.5
7
6
-
_
-
-
~
42
50
Zn
50
70
1.0
1.0
80
15
_
0.2
0.4
0.5
0.2
_
1.0
0.2
0.2
0.7
-
_
-
_
-
0.14
0.19
pH
5.5
5.5
6.2
6.5
5.5
5.8
6.8
7.0
7.0
6.7
6.6
_
4.3
7.0
7.0
7.0
C "3
0 . «J
6.5
6.3
6.3
6.2
5.9
6.3
6.8
7.1
7.0
,GAS YIELD,
itT/1000 kg dry CH4,Z
1
20
65
65
20
.
_
65
65
- *.
7.1 55
_ w
.
-
.
-
55
45
45
50
14 50
14 65
15 65
17 70
-
*C Control. No recycle and no water addition.
f Flow through of water without recycle.
M Moisture added Initially.
N Nutrient addition.
pH Adjustment to neutral pH.
R Recycle of leachate.
S Sludge seed added.
Sh Shredded solid waste.
* All expressed in mg/1 except
- Data not given
BOD5/COD, COD/TOC
, and pH.
-------
factor in precipitation of heavy metals, with the possible exception of
cadmium which was not as readily precipitated (Pohland, ^_t ad., 1981).
Leachate recycle resulted in a gas yield of 7.1 m3/1000 kg dry waste (Pohland,
1980) with a gas composition of 55 to 65% CHij and 35 to ^5% CC>2 as also
reported in two other studies included in Table 21.
Full-Scale Leachate Recycle—
As yet, no full-scale testing of leachate recycle as an in situ treatment
option in the United States has been reported in the available literature.
One full-scale study has been performed in England, and several full-scale
landfills have been provided with leachate recycle in Germany.
A demonstration project has been conducted which may be considered near
full-scale at Mountain View, CA (Pacey, 1983). This study was conceived to
verify pilot-scale observations regarding the benefits of adequate moisture
content, pH buffering and nutrient availability through controlled moisture
applications and/or leachate recycle. Six field cells were constructed to
evaluate these effects, each having an average volume of 10,500 m3 and refuse
mass of 4825 metric tons. Each of these cells was operated using different
combinations of water content, seed sludge, nutrients, and buffer. Only one
of the six cells was operated using leachate recirculation. Unfortunately,
the initial moisture application to this latter cell was somewhat drastic and
was followed by an infrequent and sporadic leachate recycle schedule which
tended to obscure the benefits of leachate recycle (Van Heuit, 1983; Pacey,
1983). Although still somewhat preliminary, the results of this study have
illustrated the benefits of pH and moisture control, i.e., cells to which
moisture and buffer were applied have produced significantly higher quantities
of gas than the control cells. Despite sporadic recirculation, the recycle
cell has produced the highest quantities of gas to date. Routine leachate
quality was not monitored, therefore, definitive conclusions regarding
stabilization patterns from this study were difficult.
A 2.5-ha landfill in England has been lined with a heavy polyethylene
membrane and filled to a depth of 3 to 4 m with refuse having a density of
800 to 1000 kg/m3 (Robinson, jrt al_., 1982). Leachate has been sprayed on the
top of the refuse using a sprinkler system. Preliminary results have
indicated that the COD of recirculated leachate is diminishing at a
significantly higher rate (^0% reduction in the first 20 months of operation)
than in a non-recirculated control area. Unfortunately, gas production data
were not available since the landfill was not covered.
Some information is available for several full-scale landfills in Germany
where leachate recycle is being used as summarized in Table 22 (Cord-Landwher,
£t al_., 1982). A two-stage approach was initiated at one of these landfills
wherein leachate was removed from a newer landfill section to be recirculated
in an older stablilized section. The 'acid-stage' (new field) had a surface
area of 0.6 ha and a refuse depth of M m; the 'methane-stage1 (old field) had
an area of 0.57 ha and a similar depth. Eight months of operating data for
this system have been presented and are summarized in terms of leachate 8005
and COD in Table 23. Results indicated that the two-stage approach may be
used to obtain consistent quantities of methane from a full-scale landfill at
a minimum cost, since the gas collection and leachate recirculation systems
would not require as frequent or extensive modifications as in the case where
the total landfill would be filled to capacity. In the staged approach,
76
-------
TABLE 22. SUMMARY OF AVAILABLE INFORMATION CONCERNING THE APPLICATION OF LEACHATE RECYCLE AT FULL-SCALE
LANDFILLS IN GERMANY
Landfill Stapelfeld
Surface
Area, ha 8
Area served,
km2 6
Population
served 70,000
Refuse
Received
kiloton/yr
m3/yr
Leachate
produced
m3/yr
m3/ha-yr
Recircu-
lation
method
sprinklers x
troughs
others
Leachate
quality
BODc.mg/L 820
COD,mg/L 1,680
pH 7.1
Start of
landfill 1973
Start of
recycle 1981
Annual
precipi-
tation, mm 750
Flechum Dorpen Venneberg Hattorf Blankenhagen Nauroth Relnstetten Kupferzell
Betterspot
(Old) (New)
2.16 5.5 6.0 9.1 18.0 7 5.1 3
8 9 3 9 12 12 30 15 12
18,000 80,000 82,100 115,310 160,000 122 112,620 85,000
62,000 51,000
17,000 70,000 65,000 100,000 180,000 120,000
1,000 570 - 1,800 7,630 - -
1,100 1 ,590 - - - 1,571
--x - -x xx
xx- x - - - -
- - - - x- -x
100 20,000 390 1,100 200 - 11)0
1,20035,000 930 2,900 - - 18,000
7.8 6.1 6.95 7.65 7.1 - 8.1
1975 1979 1976 1977 1962 1973 1975 1980
1975 1982 1980
810 700 790 - 650 1100 800 650
After Cord-Landwher, (1982)
-------
leachates collected from sections of the landfill which have not been equipped
with recirculation or gas collection appurtenances can be stabilized by the
methanogenic bacteria operative in the older sections. Moreover, this method
may significantly improve the overall yield of available methane from a
landfill while affording a lower capital investment.
TABLE 23. ORGANIC CHARACTERISTICS OF LEACHATES REMOVED
FROM A FULL-SCALE TWO-STAGE RECIRCULATION PROCESS
IN GERMANY
Date of
Sample
(1982)
2/17
3/3
4/15
5/12
6/3
7/7
7/22
8/3
Old Field
(Methane-Stage)
BOD5, COD,
mg/1 mg/1
60
64
59
—
63
67
—
60
1473
1278
1370
—
1561
1409
—
1273
New Field
(Acid-Stage)
BOD5 , COD ,
mg/1 mg/1
__
1,310
5,320
2,660
6,000
—
6,340
11 ,970
__
5,303
10,390
5,559
16,725
—
11 ,200
19,300
After Cord-Landwher, et al., 1982
PHYSICAL/CHEMICAL TREATMENT OF LEACHATES
A number of physical/chemical processes have been investigated for their
respective leachate treatment capabilities. Much of the emphasis has been on
bench-scale, although several processes have also been evaluated on full-scale.
Bench-scale investigations have included the application of chemical
oxidation, precipitation, coagulation, ionizing radiation, ion exchange,
adsorption and reverse osmosis. Full-scale investigations have been performed
on chemical precipitation/coagulation, ammonia stripping, and activated carbon
adsorption.
Bench-Scale Physical/Chemical Leachate Treatment Processes
A listing of bench-scale research activities on the reported
physical/chemical leachate processes is provided in Table 24 together with
descriptions of the processes used and the objectives of each study.
Coagulation and Precipitation—
Organics Removal—Coagulation and precipitation have been the most
extensively studied physical/chemical treatment methods for the removal of
organics and metals. Alum, ferric chloride, lime, and polymers have been used
as coagulants as summarized in Appendix Table B-1. As shown in Figure 26,
none of the coagulants tested have been successful in removing more than 30/5
of the influent COD from either raw or biologically treated leachates.
78
-------
TABLE 21. BENCH-SCALE RESEARCH PERFORMED ON LEACHATE TREATMENT BY PHYSICAL/CHEMICAL PROCESSES.
Reference
Process
Process Description
Research Object ive(s)
Source"
17.18,176
19,20
32.56,170
11-116,70,73
51,97
133
Oxidation
Disinfection
Precipitation
Coagulation
Oxidation
Precipitation
Adsorption
Coagulation
Precipitation
Adsorption
Ion Exchange
Oxidation
Precipitation
Reverse Osmosis
Adsorption
Coagulation
Oxidation
Precipitation
118,119,176 Precipitation
Adsorption
Coagulation
Oxidation and disinfection
by diffusing ozone in batch
test; precipitation by
standard batch jar test
apparatus simulating coagula-
tion, flocculation, and
settling.
Standard batch Jar test
apparatus to simulate
coagulation, precipitation
and settling.
Continuous flow adsorption
column; standard batch jar
tests to simulate coagula-
tion, precipitation and
settling.
Continuous flow column test
and batch tests for AC
adsorption; complete-mix,
batch reactor for Oj oxida-
tion; standard batch Jar
test for lime precipitation
Continuous flow column test
for AC adsorption; standard
batch jar test apparatus for
coagulation, oxidation
precipitation.
Standard batch jar test.
Continuous flow column test
for AC adsorption; standard
batch jar teat for alum
coagulation.
Effect of ozone on oxidation of Lyslmeter
organlcs and disinfection;
effect of lime addition on
organic and metal removal
Determine optimum dosage for Landfill
organic, iron, and color removal
using FeClj and alum as coagu-
lants, Clg and KMnOi) as oxidants,
lime and ^283 as precipitants.
Effect of peat adsorption for Landfill
removal of organic matter and
metals; determine optimum dosage
or heavy metal removal using
FeCl^ as coagulant and lime and
NaOH as precipitants.
Determine optimum process for Landfill
removal of organic matter using and
AC, anion exchange resin, ozone, Lysimeter
lime, and reverse osmosis for raw
leachate and biologically treated
effluents.
Evaluate effect of color removal Landfill
for effluent polishing using AC
adsorption and NaOCl oxidation;
determining optimum dosage for
organic removal using FeClj, FeSOi),
alum, and polymer as coagulants
and lime and NaOH as precipitants
for raw leachate.
Determine optimum lime dosage Lysimeter
for organic removal from
biologically treated effluent.
Determine alum dosage and AC Landfill
effectiveness for organic and
heavy metal removal for con-
ceptual design of full scale
treatment plant.
131
229
212,213
265
Adsorption
Coagulation
Oxidation
Precipitation
Adsorption
Oxidation
Adsorption
Ion Exchange
Coagulation
Precipitation
Batch test and continuous-
flow column test for AC
adsorption; all other tests
performed on a batch basis.
Batch AC adsorption test;
Batch ozone oxidation test.
Continuous upflow filters
for both AC and glauconitic
greensand.
Standard batch Jar test
apparatus.
Effect on organic, iron, and Landfill
removal by AC adsorption, alum and waste
and FeClj as coagulants; pile
Ca(OCl)2. Cl2, KMnOn and 0^ as
oxidants; and lime and Na2S
as precipitants.
Effect of AC adsorption and Lysimeter
and ozonation on removal of
organics, phenol, NHj, and
toxic organics.
Effect of AC adsorption and Landfill
greensand for metal removal.
Evaluate effect of process
sequence between adsorption
and greensand ion exchange.
Determine optimum dosage of alum
coagulant and lime precipitant
for organic, color, and metal
removal.
79
-------
TABLE 24 (Continued)
Reference
Process
Process Description
Research Objectlve(s)
Leannate
QrNir'/io *
183,205-207
151
113
Adsorption
Ion Exchange
Adsorption
Coagulation
Oxidation
Precipitation
Adsorption
Coagulation
Precipitation
Batch study for AC adsorption
tlon; Batch study for ion
exchange using cation resin.
Determine treatabillty of
aeroblcally treated leachate
effluent using cation resin,
mixed resin and PAC.
Batch test for AC adsorption; Determine adsorption capacity
Standard batch jar test for for AC on raw leachate;
alum and lime, FeSOij and lime, Determine optimum dosage
for alum, lime, FeSOi4, and
NaOCl for organic and metal re-
moval .
and NaOCl dosages.
Batch test for AC adsorp-
tion using jar test appara-
tus.
Determine adsorption capacity
of AC for chemically treated
leachate and biologically and
chemically treated leacahte;
Determine optimum dose of alum,
FeClj, and lime and optimum pH
for organic, Fe and Zn removal
for raw and biologically
treated leachate.
Landfill
and
Lysimeter
Landfill
Landfill
28
158
285
238
215,216
96
Adsorption
Coagulation
Precipitation
Adsorption
Coagulation
Ionizing
Radiation
Coagulation
Precipitation
Disinfection
Coagulation
Continuous flow column test
and batch tests for AC
adsorption; standard Jar
test to simulate coagulation,
precipitation, and settling.
Continuous flow column test
for AC adsorption; standard
Jar test for ferric chloride
coagulation.
Radioactive Isotope of cobalt
used as gamma ray source for
ionizing organic substrate.
Standard batch jar test to
to simulate coagulation,
precipitation, and settling.
Batch reactor using NaOCl as
as disinfectant.
Standard Batch jar test to
simulate coagulation and
settling.
Compare effectiveness of three Lysimeter
activated carbons for polishing
chemically and biologically
treated leachate; determine
optimum dosage of alum, lime,
and ferric chloride for organic
and iron removal.
Determine AC effectiveness and Landfill
and optimum dosage of
for organic removal.
Effect of pH, aeration rate, Landfill
and dose rate on organic re-
moval; determine molecular
weight distribution of
ionized organics.
Determine optimum dosage Landfill
of alum and FeClj as
coagulants and lime and NaOH
as precipitants for organic
and heavy metal removal.
Effect of NaOCl dosage and Landfill
contact time on bacterial
and viral inactlvatlon.
Determine optimum dosage Lysimeter
for organic and iron removal
using alum as coagulant.
239
Coagulation
Standard Batch jar test to
simulate coagulation and
settling.
Determine effects of lime Industri
dosage on color, turbidity, Landfill
and organics removal.
80
-------
The effects of coagulant dosage and pH are Illustrated in Figure 26.
Alum has been demonstrated as the most successful coagulant in dosages of
50 to 100 mg/1 and at a pH near 8.2, achieving up to 25% COD removal. Ferric
chloride and polymer" were determined to be somewhat less effective at similar
and greater dosages. For these coagulants, COD removals were typically on the
order of 10$ in the pH range of 6 to 9 and at coagulant dosages up to 1000
mg/1.
Results of chemical precipitation using lime, sodium hydroxide, and
sodium sulfide are summarized in Appendix Table B-2 and illustrated in Figure
25. The data presented in Figure 27 indicate that chemical precipitation
processes were equally unsuccessful in removing COD. Lime dosages of 1000
mg/1 resulted in only 25$ COD removals from raw leachate at pH 7. Similar
dosages for biologically treated leachates yielded 35$ COD removals. Although
the use of sodium sulfide and sodium hydroxide received only limited study,
results indicated that less than 10$ COD removal was possible at chemical
dosages upwards of 2000 mg/1.
Metals Removal—Alum, ferric chloride, and lime have been investigated
for their respective metal removal potentials as indicated in Appendix Table
B-3 for the heavy metals and in Appendix Table B-4 for the alkaline earth
metals. As summarized in Table 25, iron and zinc were removed best with 90$
or greater removals being generally achieved. Alum and ferric chloride at
dosages of less than 100 mg/1 have provided successful removals, whereas much
higher dosages of lime (500 mg/1) were required to achieve similar results.
Data for only one analysis with sodium sulfide indicated 99$ iron removal at a
1000 mg/1 dosage.
TABLE 25. SUMMARY OF HEAVY METAL AMD ALKALI AMD ALKALINE EARTH METAL REMOVAL
DATA FOR BENCH-SCALE CHEMICAL ADDITION PROCESSES
Heavy Metals
Cd Cr Cu Fe Mn Pb
Concentration
Range, mg/1 - 0.08-0.061 0.035-0.56 317-1000 0.7-25 0.10
Removal Range, > - 30-53 21-96 0-99 28-99 20
Average Removal, J - 10 10 81 66 20
Ml
73
1
1
Zn
0.1-30
0-99
86
Alkali and Alkaline Earth Metals
Ca
Concentration Range, mg/1
Removal Range , }
Average Removal, J
178
0-6
2
100-160
0-60
15
156-380
8-27
19
188
13
12
- Data not given
Lime has been shown capable of removing manganese, potassium, and sodium,
although the dosages of lime required generally greatly exceeded the
quantities of metals removed as shown in Appendix Table B-4. Alum, ferric
chloride and ferrous sulfate have received only limited study for the removal
81
-------
COD Removal, X
COD Removal,
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-------
of alkaline earth metals. From the limited data given in Appendix Table B-M,
large doses of these chemicals were relatively unsuccessful in removing the
alkaline earth metals indicated.
Chemical Oxidation—
Chemical oxidation of leachate organics has been investigated using
chlorine, calcium hypochlorite, sodium hypochlorite, potassium permanganate,
and ozone. In general, chemical oxidation processes have been slightly more
successful than the chemical coagulation and precipitation processes for COD
removal, but removal efficiencies have been too low to be considered practical.
As shown in Figure 28, 10 to 30% COD removal was typically achieved with
dosages of 2000 mg/1 of NaOCl, Ca(OCl), and Clg. Effects of ozone were
similar at lower dosages, but retention times of 3 to 4 hours were required as
summarized in Appendix Table B-5. Hypochlorites were somewhat superior to the
other oxidants studied with regard to COD removal. However, the hypochlorite
dosages required were exceedingly high.
70
60
50
3 40
O
i
a
a
u
30
20
10
LEGEND
° Ca(OCl)2
(References 1314,151)
C! C12
(Referenoea 19,131)
A KMnOi,
(References 19,131)
V NaOCl
(References 51,151)
O 03
(References 13,228)
Open symbols: Raw leachate
Shaded symbols: Biologically
treated leachate
a
a
Average-21Z
A
I
2000 4000 6000
Do«ag«, mg/1
J_
I
3000 16,000
Figure 28.
Relationship Between Chemical Oxidant Dosage
and COD Removal for Bench-Scale Chemical
Oxidation Studies
83
-------
Only one chemical oxidant, NaOCl, has been tested for the treatment of
biologically treated leachates. The application of this oxidant was
successful in removing 20 to 70$ of the residual organics (as COD) from a
biological process effluent. Although limited data were available, the best
removal (69?) was achieved at the lowest dosage (1600 mg/1) and better results
were also observed at pH 8.9 than pH 9.5 or above. Presumably, chemical
oxidation would be more logically used for this application (treatment of
biological process effluent), since the stronger oxidants would tend to
convert the refractory organics remaining after biological treatment.
Metal removal by chemical oxidation processes was studied by only a few
researchers. As shown in Appendix Table B~3, ozone treatment was successful
in removing 82 to 99% of iron, copper, and zinc. However, nickel was not
removed. The application of chlorine compounds and chlorine were also very
successful in removing iron, achieving 99% or better removal with dosages of
800 to 1000 mg/1.
Chemical Disinfection—
Ozone and sodium hypochlorite have been applied to raw and biologically
treated leachates to evaluate their capabilities for disinfection. As shown
in Table 26, ozone at 100 mg/1 decreased the bacterial density of raw leachate
to 30 CFU/ml, as determined by the Standard Plate Count Technique. This
dosage is two orders of magnitude higher than typically reported for domestic
wastewater disinfection (Venosa, 1972), since the high level of organics in
the high-strength raw leachate imposed a high ozone demand.
Disinfection of a biologically treated and diluted leachate using NaOCl
has also been investigated (Polprasert, 1977; Polprasert and Carlson, 1977).
The effects of NaOCl dosage and hardness concentration were studied for
bacterial and viral inactivation of a leachate seeded with E. coli and T-4
coliphage to increase bacterial and viral densities, respectively. A batch
reactor was used to perform the bench-scale study, and dosages of 5 to 55 mg/1
NaOCl for T = 2 to 60 minutes were used. Greater than 99% bacterial inactiva-
tion was achieved for NaOCl dosages of 1 to 20 mg/1 at a contact time of 30
minutes. The 5 mg/1 NaOCl dosage was relatively ineffective, since only 90%
bacterial inactivation occurred for a contact time of 60 minutes. Higher
dosages were necessary for equivalent viral inactivation; 99% inactivation
occurred with 48 mg/1 NaOCl at a contact time of 60 minutes, and 99.99$
inactivation occurred with 55 mg/1 NaOCl at 60 minutes contact. Overall, a
higher NaOCl dosage and a longer contact time were necessary for viral
inactivation than for bacterial inactivation. Results at hardness concentra-
tions of 250 to 1000 mg/1 as CaCO^ indicated that both bacterial and viral
inactivation decreased as the hardness concentration increased.
Chemical Process Sludge Characteristics—
Chemical treatment with coagulants, precipitants, and oxidants generally
did not achieve effective COD removal and chemical dosages were exceedingly
high and not very practical. Moreover, large sludge volumes resulted as
indicated in Figure 29. Sludge volumes greater than 5% of the original
leachate volume were typical and were occasionally as high as 30 to 40$. Lime
treatment produced the greatest sludge volume of all chemicals investigated,
while the oxidants produced the smallest sludge volumes, typically 1$.
84
-------
TABLE 26.
BENCH-SCALE RESEARCH PERFORMED WITH
CHEMICAL DISINFECTION OF LEACHATE
REFERENCE
(5,6,610
(80,81)
ITEM
Description of Study
Investigate use of Oj
for raw leachate to
inactivate bacteria
in a batch reactor.
Leachate Quality
Bacterial Density,
CFU/ml
Viral Density,
PFU/ml
COD, mg/1
TOC, mg/1
NH3-N, mg/1
Cr, mg/1
Cu, mg/1
Fe, mg/1
Pb, mg/1
Ni, mg/1
Za, mg/1
Hardness, mg/1
as CaC03
PH
Disinfectant
Dosage, mg/1
Contact Time,
minutes
Enumeration Technique
Bacteria
Virus
Conclusions
300
It,000
5,200
1.14
0.39
47
0.025
12.5
5.3
°3
10-163
Standard Plate Count.
Not determined.
Oj dosage of 110 mg/1
at unknown contact
time yielded leachate
containing <30 CFU/ml.
Study bacterial and viral
inactivation using NaOCl
for biologically treated
leachate using a batch
reactor; effect of
hardness; develop inactiva-
tion kinetic models.
0.05-33 x 10? (seeded)
0.7-1.0 x 10? (seeded)
150
1.8
280-1000
7.6
NaOCl
5-55
2-60
Membrane filter
(Refer to Sobsey, et al.,
1971)
Viral resistance to dis-
infection > bacterial
resistance; hardness inhi-
bited both bacterial and
viral inactivation of
NaOCl.
85
-------
80
60
40
LEGEND ft
& Coagulants (Al2(SOi,) ,FeCl3, FeSOi,)
O Precipitant3 (Ca(OH)2, Na2S)
Q Oxidants (CaOCl)2, C12, NaOCl, KMnOt,, 03)
. Plus 1000-1600 mg/1 Ca(OH)2
Open symbols: Raw leachace
Shaded symbols: Biologically Created
leachate •
30 _
•a
AA
20
10 _
A
D
zS a
) O
HA
)
a o a
Q Q
a •
0° " °
a °Qo%
°° ^ ° A 9 ° °
• a A
A D a a a a
A A a A o -A
H A Oa * * A A *
a u . A A A
LJ « £h
B D
•J a B. ^ 1 r, 1 i/fl I I
500 100° "00 2000 2500 * 5000 10,000 15,0
Dosage, mg/1
50
40 —
LEGEND u
A Coagulants (A12(SO,,) , FeCl3, FeSOi,)
D Preclpitants (Ca(OH)2, Ha2S)
Oxldants (Ca(OCl)2, C12, KMnO^)
. Plus 1000-1600 mg/1 Ca(OH)2
Open synbols: Raw leachate
Shaded symbols: Biologically treated leachate
30 —
a a
20 -
10
a
a
B°
a &
- = ». '
A a
_m a
A Olll
3 500
ap a a a
A A a
A •
O • A
LS ^
d
*• § A 10 q> i /I o | o | o j
1000 1500 2000 2500 K 5000 10,000 15,
Dosage, mg/1
Figure 29. Comparison of the Organic Removal Efficiencies and
Sludge Volumes Produced by the Application of
Various Chemical Dosages to the Treatment of
Leachates on Bench-Scale
86
-------
Ionizing Radiation—
The application of ionizing radiation for the treatment of landfill
leachates has been tested by one investigator (Yamazaki and Sawai, 1981). A
medium-strength leachate (2000 mg/1 TOO was radiated with a 5-Kilocurie (KCi)
6°Co source which emitted an average dose of 0.6 mrad/hr. The effects of pH,
aeration rate, and radiation dose on TOC removal were evaluated at room
temperature. Maximum TOC removal (75%) was achieved at pH 4 and a radiation
dose of 20 mrad/hr. At low radiation doses, aeration increases yielded
increased TOC removals; these effects were much less noticeable at higher
doses. As a result of the applied radiation, the organic compounds present in
the leachate were converted from high molecular weight compounds to low
molecular weight compounds. Humic and fulvic acid fractions were converted to
low molecular weight carboxylic and phenolic compounds, alcohols, and other
substances. Leachate biodegradability was believed to have improved as a
result of the radiation, since it produced low molecular weight compounds. As
such, this process may hold promise as a pre-treatment prior to more complete
biological removal of organic constituents.
Ion Exchange—
Anionic and mixed ion exchange resins have been evaluated for polishing of
biologically treated leachates as indicated in Appendix Table B-6 and
summarized in Table 27. COD and TOC removals by ion exchange from these
low-strength wastewaters ranged from 10 to 70% in both batch and continuous
processes.
TABLE 27. SUMMARY OF ION EXCHANGE PERFORMANCE USING EFFLUENTS FROM
AERATED LAGOON AND ACTIVATED SLUDGE LEACHATE TREATMENT SYSTEMS
Influent
Concentration
Leachate
Reference
11,15,70
11,15.70
205,207
205 . 207
Process
Anlon
Exchange
Anlon
Exchange
Anlon
Exchange
Anlon and
Cation
Exchange
Type
AL
AL
AS
AS
pH
8.8
6.2
5.0-7.7
7.3
mg/1 Removal, {
COD
500
500
180
185
TOC COD TOC Comments
200 6-59 26-13 Continuous
200 18 13 Continuous
68-36 - Batch;2-10 g/1
10 - Batch;?-10 g'l
Cationic ion exchange has also been studied for the removal of metals
from leachates using glauconitic greensand (GG) a common geological stratum
indigenous to the Delaware and New Jersey regions of the United States and
reported as having significant cation exchange capacity (Spoljaric and
Crawford, 1979 a,b). The research focused on the effects of flow rate on
metals removal in a continuous flow processes with flow rates of 0.1 and 1.0
1/min, As shown in Table 28, the lower flow rate provided better removal
copper, lead and nickel (96% or greater) over iron (86%) and zinc (67%). This
is in contrast to the other treatment processes (biological and chemical
addition studies) where iron and zinc were typically most affected and lead
and nickel were least affected. Chromium, manganese, calcium and magnesium
were fairly well removed at the lower flow rate, whereas, potassium and sodium
were poorly removed. Although the cation exchange capacity of GG is low
(2.1-3.6 meq/100 g), this process could be economical depending on handling
costs for the exchange media.
87
-------
TABLE 26. SUMMARY. OF GLAUCONITIC GREENSAND (GO) PERFORMANCE FOR THE REMOVAL OF METALS FROM LEACHATE
Influent
Concentration,
mg/1
Reference Parameter
29,170 Cd
Ca
Cr
Cu
Fe
Pb
Mg
Mn
Nl
K
Na
Zn
pH
0.1 1/min
0.006
129
0.03
0.38
8.1
0.13
62
1.1
0.07
122
275
0.19
7.7-6.3
1 .0 1/mln
0.08
181
0.13
0.28
11.0
0.18
161
6.1
0.21
361
585
0.78
7.5-6.6
Removal ,
*
0.1 1/mln
83
63
66
99
86
99
67
88
96
39
36
67
1 .0 1/mln
96
22
-
11
3
13
26
18
1M
62
0
20
Comments
Continuous flow,
upflow sand filter
bed. Lower flow
rate provided
better removal;
exchange capacity
on the order of
2.1-3.6 meq/100g.
Adsorption—
The adsorption of organics and metals from leachates has been studied
using activated carbon and peat. Activated carbon has received the vast
majority of study, having been evaluated in batch and continuous processes
with granular and powdered carbons. The evaluations have generally involved
the use of biologically or chemically treated leachates. The biological
treatment effluents were typified by COD concentrations ranging from 200 to
800 mg/1, whereas, the chemical treatment effluents generally contained
2000 to 3000 mg/1 COD.
As indicated in Appendix Table B-7, activated carbon was generally
capable of removing 30 to 70% of the residual COD and TOC at retention times
of 1 to 15 minutes in continuous flow processes. Removal efficiencies were
lower for chemically treated leachates than for biologically treated leachates.
Further comparison of these wastewaters is provided in Figure 30 by Freundlich
isotherms for the batch adsorption studies listed in Appendix Table B-7. The
COD and TOC based isotherms shown in the figure have steep slopes, suggesting
that continuous operation would be more efficient than batch adsorption.
Although limited data were available, the biologically and chemically treated
leachate isotherms were fairly similar, having similar relationships between
the equilibrium organic concentration and the adsorptive capacity of the
carbon. The raw leachate isotherms deviated from the other two, due mainly to
the higher concentrations of organics imposed, but also to some degree to
differences in organic composition. A summary of the Freundlich isotherm
parameters derived from each case is provided in Table 29.
TABLE 29. SUMMARY OF FREUNDLICH ISOTHERM PARAMETERS FOR BENCH-SCALE ACTIVATED CARBON ADSORPTION
OF RAW LEACHATE AND TREATED LEACHATE
References
15,131,151
15,205
28,113
113
X/M, 1/n,
mg COD or TOC mg COD or TOC
COD C0> mg/1 mg AC mg AC-mg/1
Leachate Type TOC COD TOC COD TOC COD TOC
Raw - 5000 395-13,000 2.5 0.016-0.30 9.5 0.6-1.2
Biologically 2.1-3.8 181-830 210-320 0.261-0.51 0.102-0.71 0.7-2.3
Treated
Chemically 3-3-3-7 508-2990153-150 0.20-0.80 0.11-0.165 1.1-3.2 0.97-1.1
Treated
Biologically 3.0-3.7 192-311 130-230 0.15-0.66 0.13-0.23 0.98-5.9 2.1-2.9
Plus Chemically
Treated
X/M ' KC01/n
-Data not given.
-------
4.0
1 r-T
LEGEND
I I HI)
I I I I I I I II
1 I I I I II
1.0
Raw Leaohate
(Reference 131)
Biologically Treated Leachate
(References 15.205)
Chemically Treated Leachate
(References 28,113)
Biologically Plus Chemically
Treated Leachate
(Reference 143)
0.1
0.01
10
100 1000
COD Equilibrium Concentration (Co), uig/1
10,000
0.4
0.1 _
0.01
0.001
I 1—I I I I
Raw Leachate
(References 15,131,151)
Q Biologically Treated Leachate
(Reference 15)
A Chemically Treated Leachate
(Reference 113)
V Biologically Plus Chemically
Treated Leachate
(Reference 113)
100
1000
10,000 20,000
TOG Equilibrium Concentration (C-), mg/1
Figure 30. Freundlich Isotherm Curves for Bench-Scale
Batch Activated Carbon Treatment of Raw,
Biologically or Chemically Treated Leachates
89
-------
Peat adsorption studies (Lidkea, 1974; Corbett, 1975; Cameron, 1978) on
organic and metals removals from leachate are summarized in Table 30.
Continuous flow columns filled with dried peat were used to evaluate the
effects of pH on process performance. Alkaline conditions were more effective
than were acidic conditions. At pH 7.1 to 7.8, the peat columns removed 86?
COD, 95% NH3~N and greater than 90% of all metals studied except lead. Metals
removal was attributed to a combined precipitation/filtration mechanism at the
alkaline pH values.
TABLE 30. SUMMARY OF THE PERFORMANCE OF PEAT FOR ADSORPTION OF
ORGANICS AND METALS FROM LEACHATE
References
Parameter
Leachate
Concentration,
mg/1
Removal ,
Comments
32, pH
56,
170 COD
TKN
Ca
Fe
Pb
Mg
Mn
K
Na
Zn
4.8
830
-
254
27
0.03
106
0.52
580
1400
0.43
7.1
830
465
174
22
0.06
126
0.61
126
780
0.60
4.8
66
-
66
82
98
55
67
71
70
47
7.1
66
95
92
99
73
96
92
96
95
90
Continous
upflow
column
using dried
peat as an
adsorption
media
Metals Removal—
A summary of heavy metal and alkali and alkaline earth metals removals
achieved by the ion exchange and adsorption processes is provided in Table 31•
Due to the limited data available, definitive statements are not possible,
although the ion exchange appeared to be superior to adsorption for the
removal of both heavy and alkaline earth metals.
As indicated in Appendix Table B-8, activated carbon was successful in
removing 96% of the iron from raw and ozonated leachates; the performance
achieved seemed dependent on carbon dosage. Using batch adsorption tests, an
8 g/1 dose of powdered activated carbon (PAC) improved iron removal from 73%
90
-------
at a 2 g/1 dose to 96? (Ho, jet al., 1974). Further increases in carbon dosage
yielded little improvement (97% iron removal at 16 g/1 PAC dose). Data
provided in the literature for other metals were insufficient for comparison.
TABLE 31. SUMMAR* OF HEAVY METAL AND ALKALI AND ALKALINE EARTH METAL REMOVAL DATA WITH
ACTIVATED CARBON ADSORPTION AND RESIN ION-EXCHANGE TREATMENT OF LEACHATE
Heavy Metals
Cd Cr Cu
Concentration 0.03-0.08 0.07-0.13 0.21-0.28
Fe Pb Mn Ni Zn
11-66 0.18-0.23 6.1-25 0.13-60 0.7-60
Range, rag/1
Removal
Range, 1 27-96 0 0-11 10-97 22-33 21-87 0-37 0-99
Alkali and Alkaline Earth Hetala
Ca Mg K Na
Concentration Range,
fflg/1
Removal Range , $
15-181
0-95
15-161
0-99
63-380
0-95
200-585
0-99
*Not applicable. Not sufficient data for true statistical average.
"Activated Carbon (AC); Ion Exchange (IX)
-Data not given.
The removal of alkaline earth metals from raw leachates was also somewhat
varied and, although limited data were available, it appeared that ion
exchange offered better removal than adsorption. A batch activated carbon
study of metals removal (Karr, 1972) indicated that manganese was best
removed, but it was also present in lowest concentration as indicated in
Appendix Table B-9. Calcium, magnesium, and potassium, present in higher
concentrations, were removed by 40? or less. The ion exchange processes were
more successful in removing these constituents, typically exhibiting 75 to 95%
calcium, >95% magnesium, 50 to 95? potassium, and up to 99? sodium removals
for biologically treated leachates, depending on the resin type and dosage
applied.
A comparison of ion exchange (IX) and activated carbon (AC) treatment of
raw leachate is also presented in Appendix Table B-9. The limited data
presented seem to suggest that glauconitic greensand is superior to AC at
similar flow rates and bed volumes. At lower flow rates, the superiority of
IX becomes increasingly evident.
Reverse Osmosis—
Reverse osmosis has received consideration as both an initial (raw
leachate) treatment step and a final polishing step (using biological, AC or
IX treatment process effluents). Raw leachates were initially studied (Chian
and DeWalle, 1977b) and, as summarized in Table 32, reverse osmosis (RO) was
fairly efficient in removing the majority of the residual TOC. Two types of
RO membranes were used, each having different polar characteristics: The more
91
-------
polar membrane (NS-100) achieved slightly superior TOG removal than the
cellulose acetate (KP-98) membrane at both pH 5.5 and 8.0, although the
difference in performance was much more marked at pH 5.5.
The major problem associated with RO treatment of .raw leachates was
membrane fouling due to solids, colloidal material, and iron hydroxides.
Therefore, emphasis was also placed on the removal of TOG from aerated lagoon,
activated carbon, and ion exchange process effluents using RO as summarized in
Table 32.
TABLE 32. SUMMARY OF REVERSE OSMOSIS PERFORMANCE FOR THE REMOVAL OF
COD FROM RAW AND BIOLOGICALLY TREATED LANDFILL LEACHATES
Leachate
References Process Type pH
44,45,70
*1 psi =
AS =
AL =
Reverse Raw 5.5
Osmosis
Raw 5.5
AL 8.8
AC 8.8
IX 5.5
6.895 kN/m2
Activated sludge effluent
Aerated lagoon effluent
Influent
COD,
mg/1
13,000-
18,500
13,000-
18,500
214
48
119-143
COD
Removal , %
85-98
98-99
95
86
94-97
Operating
Conditions*
P=600,1500
psi, (KP-98)
P=600,1500
psi, (NS-100)
P=600 psi
P=600 psi
P=600 psi
AC = Activated carbon effluent
IX = Anion exchange effluent
Only the NS-100 membrane was utilized for the treated leachate tests, since it
was found to be superior with raw leachate. Application of RO to the
activated carbon treatment effluent was the least successful, achieving only
86? TOC removal as compared to 94 to 96$ removals for aerated lagoon and ion
exchange treatment effluents. Although successful as an effluent polishing
measure by itself, the problem of membrane fouling was considered serious
enough to warrant filtration or coagulation of the treatment effluents prior
to RO polishing (Chian and DeWalle, 1977b).
92
-------
Full-Scale Physical/Chemical Leachate Treatment
Chemical treatment using coagulants and precipitants, NH^ stripping, and
activated carbon adsorption have been tested at several full-scale leachate
treatment facilities. These studies are summarized in Table 33 along with a
process description and location of the landfill and treatment facility. All
of the landfills were classified as municipal solid waste landfills except for
the Love Canal landfill (McDougall and Fusco, 1980; McDougall, et al., 1980).
TABLE 33. FULL-SCALE LEACHATE TREATMENT FACILITIES
USING A PHYSICAL/CHEMICAL PROCESS
Reference
Process
Process Description
Location
26
Precipitation
Lime addition for heavy
metal removal.
North Hempstead,
New York
133
178,
179
231
2M8
Coagulation and
Adsorption
Adsorption
Chemical
Addition
Precipitation;
NHg Stripping;
Nuetralization
Alum and polymer addition
for pretreatment prior to
AC adsorption for organic
and heavy metal removal.
NaOH addition for pretreat-
ment prior to AC adsorption
for removal of toxic
organics, most classified
as priority pollutants.
Chemical addition prior to
treatment by aerated lagoon
and activated sludge.
Lime addition for heavy
metal removal and to raise
pH; Air stripping of NH3 at
alkaline pH using a lagoon;
Sulfuric and phosphoric acid
addition for neutralization.
Franklin County,
Pennsylvania
Love Canal,
New York
Pennsylvania
(2 landfills)
Bucks County,
Pennsylvania
Precipitation/Coagulation—
Chemical addition has been the most common full-scale physical/chemical
process used for landfill leachate treatment. A summary of the treatment
performance and design parameters for the full-scale treatment facilities
using this approach is included in Table 3*1. The available information has
been separated into influent and effluent quality, pretreatment, treatment,
and sludge characteristics.
93
-------
TABLE 34. SUMMARY OF PERFORMANCE AND DESIGN PARAMETERS FOR FULL-SCALE
PHYSICAL/CHEMICAL LEACHATE TREATMENT FACILITIES
— ^_^_REFERENCE
Process
Influent Quality
BODc, mg/1
COD, mg/1
TOC, mg/1
TKN, mg/1
NH,-N, mg/1
TDS, mg/1
Cd, mg/1
Cr, mg/1
Cu, mg/1
Fe, mg/1
Pb, mg/1
HI, mg/1
Zn, mg/1
pH
Q, mj/day
Pretreatment
Treatment
Coagulation-
Flocculation
Dosage, mg/1
T, minutes
pH
Settling
T .hours
Overflow rate,
m3/m^* day
NH3 Stripping
T.days
pH
(26)
Precipitation
10,000
14,000
.
700
600
_
0.05
-
-
1000
-
.
8
6.0
136-.245
Preaeration
1650, Lime
15-30
-
3-.1.7
20,37
No
(133)
Coagulation
Adsorption
100
-
-
10
.
-
-
0.56
20
0.10
-
-
7.6
71
No
-,Alum
-
-
4
15
No
(173,179)
Adsorption
11,500
4300
-
.
.
-
-
-
330
0.4
-
-
5.6
65
Caustic Addition,
multi-media
filtration
-
-
No
(231)
Chemical
Addition
2500
-
90
50
-
-
-
-
750
-
-
20
6.0
549
No
-
-
No
Precipitation
NH, Stripping
4 SI*
11,900
18.500
-
760
760
13,500
0.08
0.26
0.40
333
0.74
1.76
20
6.7
79.5
No
3000, Lime
-
-
11
7.6
12
10
(245-248)
Precipitation
S2*
10,400
16,600
-
1170
1170
12,700
0.07
0.25
0.46
350
0.75
1.58
19
6.9
86.3
No
3600, Lime
-
9.0-11.7
10
8.2
No
Precipitation
NH, Stripping
3 S2*
11,700
18,600
-
785
785
10,500
0.09
0.25
0.43
300
0.68
1.60
16
6.9
86.3
No
2300 .Lime
-
9.0-11.7
10
8.2
11
10
-------
TABLE 34 (Continued)
1
AC Adsorption
T.min
X/M, mg TOC/g AC
Effluent Quality
BODc, mg/1
COD, mg/1 (%R)
TOC, mg/1 (%R)
TKN. mg/1 (%R)
NH,-N, mg/1 («R)
TDS, mg/1 (*R)
Cd, mg/1 (%R)
Cr, mg/1 (%R)
Cu, mg/1 (%R)
Fe, mg/1 (%R)
Pb, uig/l (%R)
N1, mg/1 (%R)
Zn. mg/1 (*R)
PH
Sludge Character-
istics
Effluent Disposal
No
-
-
-
-
-
-
.
-
.
2.3(>99);
12(99)
-
-
0.03(>99);
0.03(>99)
-
1230 kg/day
generated
-
3
-
28(72)
-
-
.
1.7(83)
-
-
-
-
-
0(>90)
-
-
7.4
_
Surface water
2-9070 Kg GAC units No
In series
.
200
.
200(92)
100(98)
20(78)
15(70)
-
.
-
.
5(99)
-
-
2(90)
7.5
_
POTM Surface water
No
3930(67)
6890(63)
_
350(54)
350(54)
6000(56)
0.03(60)
0.07(70)
0.31(23)
3.2(99)
0.17(77)
0.61(65)
0.6(97)
8.6
_
Surface water or
No
5270(49)
7200(57)
_
890(24)
890(24)
7970(37)
0.03(60)
0.09(60)
0.10(80)
4(99)
0.24(68)
0.57(64)
0.6(97)
8.5
_
spray Irrigation
No
3600(69)
8800(53)
_
410(48)
410(48)
4650(56)
0.04(60)
0.08(70)
0.27(37)
6(98)
0.23(66)
0.73(54)
0.9(94)
8.7
.
*S1 = System 1; S2 = System 2
-------
Lime was the only precipitant used for organic and metals removal. Very
high lime doses of 2300 to 3600 mg/1 were necessary to achieve about 50 to 70%
6005 and COD removal. As with the bench-scale processes, the removal of heavy
metals was significant, especially in the case of Fe and Zn where 98 to >99?
removal was achieved at influent concentrations of 300 to 1000 mg/1 Fe and
8 to 20 mg/1 Zn. The other heavy metals, Cd, Cr, Cu, Pb and Ni, were also
removed, but influent concentrations were typically less than 1 mg/1 and a
correspondingly high removal efficiency would not be anticipated. Although
the effectiveness of lime in decreasing heavy metal concentrations at the
full-scale treatment operations was similar to that for the bench-scale
studies, less than 40? COD removal was generally achieved in the bench-scale
studies. Greater COD removal was achieved on full-scale, most likely as a
result Of prior NH^ stripping which also promoted the removal of volatile
organics. As indicated in Table 34, the NH^ stripping step was performed at
pH 10 in a lagoon having a detention time of 11 to 12 days.
Alum was also used in one full-scale treatment facility to treat a
low-strength leachate characterized by a 6005 concentration of 100 mg/1
(Hemsley and Koster, 1980). This facility was able to achieve about 70% BOD^
removal, but the alum dosage was not reported. Additional 8005 removal was
achieved with AC adsorption following alum coagulation of the leachate.
However, these two processes were not separately monitored and their
individual removal contributions were not noted.
Ammonia Stripping—
Ammonia stripping has been attempted at one landfill under two different
treatment conditions as indicated in Table 34. The leachate was pretreated
with lime to raise the pH'to about 10 and air stripping was then applied for
NH^ removal. The stripping process occurred in a large lagoon having a
detention time of 11 to 12 days. Ammonia nitrogen removal for the two
conditions ranged from 48 to 54? with influent NH-^-N concentrations of 760 to
785 mg/1. Given the long detention time used, NHg-N removal by stripping was
not as promising as would be expected. Operational problems with pH control
might have been the cause of the relatively poor stripping efficiency.
Activated Carbon Adsorption—
Activated carbon adsorption was applied at two landfills for polishing
following alum coagulation (Hemsley and Koster, 1980). Approximately 70% BOD^
removal was achieved by this treatment process when the influent concentration
was 100 mg/1 8005.
The use of AC adsorption of leachate produced from a landfill used pri-
marily for the disposal of organic chemicals has also been reported (McDougall
and Fusco, 1980; McDougall, et_ al., 1980). Following caustic addition and
multi-media filtration, two granular activated carbon adsorption units were
used to polish the effluent prior to discharge to a publically owned treatment
work (POTW). The adsorption process was found to be 98? efficient in TOC
removal for an influent TOC concentration of 4300 mg/1. The maximum
adsorptive capacity was 200 mg TOC/g AC and the treated effluent contained
about 100 mg/1 TOC and priority pollutant concentrations that were typically
below detectable limits.
96
-------
FINAL LEACHATE DISPOSAL
Following treatment of leachates by any of the previously discussed
processes, ultimate disposal in an environmentally sound manner will be
required. Options available for ultimate disposal include land application,
discharge to surface waters, and discharge to a publicly owned treatment works.
Land Disposal
Land application of treated leachates has been tested on full- and
bench-scale. Full-scale land applications by spray irrigation and
ridge-and-furrow methods have been reported as indicated in Table 35.
Unfortunately, the capabilities of these applications for final pollutant
attenuation could not be ascertained, since groundwater quality was not
monitored and soil characteristics at each land application site were not
revealed. From a hydrologic perspective, the application rates used were
apparently acceptable, since problems associated with over-application (such
as flooding) were not reported.
TABLE 35. EFFLUENT DISPOSAL PRACTICES EMPLOYED BY FULL-SCALE
LEACHATE TREATMENT FACILITIES
Land
Application Leachate Quality
Disposal Flow, Rate, Prior To Disposal
Reference
15
15
26
113-
115
166
187
231
244
245-
248
Method*
SW
SW
POTW
Ridge and
furrow
SW
SI
SW
SI
SI
SW
np/day
355
45.4
303
39
77.8
150
549
13
39-78
39-78
1/m^'day
NA
NA
NA
4.7
NA
9.4
NA
10
0.37
NA
BODq,
mg/1 COD, mg/1 pH
10 - 7.5
920
-
<800
10
1200
100
25
120-21
120-21
7.4
-
<1500
120 7.3
2280
-
-
50 940-4650 7.6-8.6
50 940-4650 7.6-8.6
*POTW = Discharge to publicly owned treatment works
SI = Spray irrigation
SW = Surface water discharge
- = Data not given
NA = Not Applicable
97
-------
Discharge to POTW
One alternative for the ultimate disposal of treated leachates is the
discharge to publicly owned treatment works (POTW). This practice must also
be evaluated on a site-specific basis, since leachate quantity and quality may
affect the performance of the POTW. Data from one landfill utilizing this
discharge method are indicated in Table 35, although no data on leachate
quality were given. The leachate apparently posed no detrimental effects on
the quality of the effluent from the POTW.
More data were available from a bench-scale study designed to simulate
the spray irrigation process (Chan, et_ al_., 1978). A test column was
constructed and filled with native soil from"the landfill site. Lime treated
leachate was then applied at 37 l/m^-day or at a loading rate chosen to
stimulate conditions planned for full-scale operation. The lime treated
leachate was characterized by 5400 mg/1 COD, 690 mg/1 Na, 540 mg/1 K, 600 mg/1
Ca, 104 rag/1 Mg, and a pH value of 10. Divalent cations were better
attenuated in the soil (comprised of 12% clay) than the monovalent cations,
and complete COD breakthrough occurred in less than three bed volumes.
Consequently, land application would be better practiced for lower-strength
leachates. More research is needed on the fate of pollutants in actual
leachate land spreading settings.
Surface Water Discharge
Discharge of landfill leachates to surface waters is subject to the same
restrictions as applied to any point source wastewater. Accordingly, the
quality of leachate required prior to surface water discharge is dictated by a
number of site-specifio technical and regulatory factors, including the
assimilative capacity of the receiving water. If leachate quality exceeds
recommended limitations, alternative disposal options must be sought. No data
were available in the literature on the use of direct discharge of untreated
leachates for ultimate disposal.
98
-------
SECTION 7
GAS MANAGEMENT
GENERAL PERSPECTIVE
The release of gases by biological activity or by evaporation
(volatilization) of waste constituents may pose certain hazards to landfill
operators and/or nearby residents. As previously outlined, the most obvious
of these hazards include the potential for fires and explosions. The control
of hazards has led to the development of various strategies for landfill gas
control and an emphasis on gas collection and energy recovery. Accordingly,
the state-of-the-art in landfill gas management includes an integration of the
elements of landfill lining (containment) with gas collection, treatment and
possible power generation. Although the latter subject was considered beyond
the scope of this report, the technology associated with landfill gas-fired
electrical generation is essentially identical to that associated with other
fuel sources and is generally on-the-shelf and available from a number of
manufacturers. Similarly, liner technology has been addressed elsewhere, and
has been the subject of several recent review publications (Landreth, 1980;
EPA, 1983; National Sanitation Foundation, 1983).
The purpose of this section is to present an overview of literature
pertinent to factors affecting gas production and a summary of reported gas
yields, composition and production rates associated with various landfill
operations. In addition, gas collection and treatment technologies (for both
on-site generation and pipeline uses) will be briefly introduced in somewhat
less detail than presented in Section 4, since these subjects have been
comprehensively addressed by others (EPA, 1979; EMCON, 1980; DOE, 1981;
Halvadakis, e_t _al_., 1983). Moreover, attempts at providing updates on
full-scale operations were hampered by the brevity, lack of data and the
presumptive nature of many of the reports constituting the available
literature.
GAS PRODUCTION
The sizing and implementation of gas handling equipment requires a
prediction of gas production rates, yields, and gas composition from a
particular landfill setting. Such a prediction may be based on theory or
formulated from comparisons with empirical results from published laboratory
and field experiences. In either case, an understanding of the biochemical
and physical factors affecting gas production and of site conditions is
necessary. In particular, the phasic nature of landfill stabilization
(SECTION 3) and the corresponding biophysical variations must be coupled to
the refuse placement and leachate control technologies being utilized.
Integration of time-dependent gas quantity and quality expectations (Figure 1,
99
-------
Table 3) with refuse placement schedules may provide for a redundant use of
both gas and leachate handling equipment, particularly where leachate recycle
is being implemented. Therefore, the following briefly summarizes the factors
affecting gas production in landfills, with an emphasis on methanogenesis
(Phase IV, Figure 1). Theoretical gas yield models are then reviewed,
followed by a summary of gas production rates, compositions and total methane
yields reported in the literature.
Factors Affecting Landfill Gas Production
Gas production in landfills is affected by many variables, including the
nature of wastes placed, moisture content, particle size and degree of refuse
compaction, buffer capacity, nutrient sufficiency, temperature, and the gas
extraction method. These factors have been reviewed in detail by Rees (1980)
and Halvadakis, ^e_t al_., (1983). From these and other sources, the following
general conclusions may be offered regarding the influence of these variables
on gas production.
Nature of Refuse Placed—
As reviewed previously, the sources of solid waste placed in a sanitary
landfill are largely a function of location and may vary considerably
according to residential, commercial or industrial origin. The nature of
these wastes influences the potential for gas production in terms of:
1) the relative availability of a usable substrate, including its organic,
moisture and nutrient contents; 2) the presence of potential inhibitors; and,
3) the formation of localized "micro environments" which may be isolated from
the overall liquid or gaseous transport phases. As indicated in Table 2,
paper products are a major contributor to the overall composition of refuse,
although these are generally more resistant to biodegradation than food and
most garden wastes. Industrial wastes are important with regard to the
buffers and metallic and other constituents they provide and may impart either
benefical or detrimental influences depending on their relative magnitudes and
propensity for reaction.
Moisture Content—
Water or moisture (leachate) provides the transport phase for organic
substrates and nutrients and is also instrumental in establishing the
anaerobic environment needed for methane production. Up to a point,
increasing the moisture content increases the rate of methane production and
the ultimate methane yield. In general, it may be expected that methane
production rates will increase with increasing moisture up to approximately
60% (W% solids), with higher moisture imparting neither an increase nor a
decrease in the maximum gas production rate.
Eliassen (1975) considered the moisture content requisite for biological
decomposition and reported optimum moisture ranges of 50 to 70? and 30 to 80%
for new and older landfills, respectively. Chian and DeWalle (1979) reported
that 15% moisture content or above was best for biodegradation of municipal
solid waste, although the presence of more water was also recognized as
resulting in production of larger quantities of leachate requiring treatment.
In spite of these observations, the large number of interrelated variables
involved in these studies has precluded a clear determination of moisture
effects; uniformity of moisture is probably equally important as quantity of
moisture, as demonstrated to some degree by leachate recirculation studies.
100
-------
Particle Size and Degree of Refuse Compaction—
Particle size reduction by refuse shredding may be expected to increase
gas production rates by increasing the surface area available for leaching
and/or biological activity, and by improving the ability to retain moisture
(DeWalle, et al., 1978; Fungaroli 1979), although Buivid (1980) reported
contrary results. Therefore, none of the results of these studies are clearly
conclusive, primarily due to the wide number of variables involved.
Literature data on refuse density and/or effects of compaction are
likewise inconclusive. Compaction will tend to optimize the volume of waste
which can be placed in a given landfill volume. However, compaction may be
expected to impede moisture and gas flow through the wastes, thereby
increasing the potential for microenvironment formation and leading to
decreased refuse stabilization or methane release rates. Therefore, more
focused and systematic studies are needed on both of these operational
variables.
Buffer Capacity—
Buffer addition has been repeatedly demonstrated as beneficial to
accelerating biological stabilization and increasing gas production rates
(Pohland, 1980; Pacey, 1983). Sufficient buffer is needed to moderate the
effects of volatile acids and other acid products which tend to depress the pH
below the desired level for methanogenesis (pH 6.6-7.4). As yet, no
systematic studies of specific buffer additions to landfills have been
performed. The practice of buffer addition is expected to be quantitatively
linked to site specific variables. Therefore, the approach to buffer addition
could be based on leachate analysis and application during leachate recycle or
by injection, or on anticipated need and augmentation of the refuse as it is
being placed. Addition of digested sewage sludge to the refuse during
landfilling is an example of the latter approach.
Nutrients—
The same considerations mentioned for buffer applications apply for
nutrient additions. Nutrient sufficiency may be best assured through initial
addition or after leachate analysis by augmentation as needed again through
leachate recycle or injection. Municipal solid wastes generally contain the
nutrients necessary for effective biological conversion, although Pohland
(1975) has shown that phosphorus may become limiting during the latter stages
of biostabilization. Nutrient additions to simulated landfill cells have not
produced distinguishable effects, again due to other operational differences
and, in particular, the fairly common practice of adding microbial seed along
with nutrients. If control over stabilization rates and gas production are
considered crucial, the issue of nutrient sufficiency should again receive
more systematic study.
Temperature—
Temperature affects microbial activity within landfills and vice versa.
In the upper aerobic layers (1 to 2 m), temperatures may range from 50 to
70°C, whereas, at lower aerobic levels (2-3 m), temperatures generally range
from 25 to 40°C. Following the depletion of oxygen and the change from
aerobic to anaerobic metabolism, temperatures within the landfill will
decrease and remain moderated by ambient conditions. Rees (1980) reported on
a method of landfill temperature moderation by utilizing a refuse placement
strategy which takes advantage of aerobic biological heat generation. Fresh
101
-------
wastes were placed in areas adjacent to regions of active methanogenio
stabilization to promote accelerated conversion made possible at the higher
temperatures.
Gas Extraction—
The withdrawal of landfill gases at rates higher than their biological
production will lead to the introduction of air into the landfill. This may
not only inhibit the methanogens, but lead to excessive quantities of nitrogen
and oxygen in the product gas. The latter consequence would correspondingly
decrease the overall energy value of the gas and require otherwise unnecessary
and expensive gas treatment. (There have been undocumented reports of reduced
methane generation rates of landfill sites operated with gas extraction
facilities.)
Gas Yield Projections
Ultimate gas (methane) yields are important in determining the economic
feasibility of gas recovery projects. However, they are not very useful in
sizing recovery equipment unless coupled to a prediction of measurement of gas
yields. Several methods are available for formulating gas yields, including
both theoretical and empirical approaches. These are reviewed in more detail
by EMCON (1980) and Halvadakis, et al_. (1983) and are briefly summarized here.
Theoretical Models—
Stoichiometric Methods—A number of investigators have derived gas
production estimates by making assumptions on the chemical composition of
municipal solid wastes (MSW) and applying these assumptions to the Buswell
equation for methanogenesis. This analysis may be performed using the entire
MSW content or by making assumptions about biodegradabilities of the major
waste fractions, e.g., food and garden wastes, papers, textiles, wood,
leather, etc. In performing such an analysis, chemical formulas for MSW
listed in Table 36 are combined with Equations 2 or 3 below, either using a
formula for the overall MSW or a summation of yields from its individual
components. The number of moles of each compound can then be calculated based
upon the quantity of wastes handled, and the equations can also be used to
determine the resultant moles or volumes of gas to be expected upon conversion
of the waste.
Buswell equation:
Wb + (n - Tf - I)H2° * (l - I + !)C°2 + (l + f - ¥
Modified Buswell equation (Mao and Pohland, 1973):
CaHbWe + <* - ! - I + F * f >"20 * (f + | -
(f --| + ir + -r + f)C02 + dNH3
102
-------
TABLE 36. EXAMPLES OF MUNICIPAL SOLID WASTE CHEMICAL FORMULAS
APPLIED TO THEORETICAL METHANE YIELD MODELS*
Waste Component
Chemical Formula
Municipal Solid Waste
Paper, Garden Wastes, Wood
Food Wastes
Cellulose
C203H334°138N
C6«1 o°5
*Adopted from EMCON, 1980.
Examples of these calculations as well as assumptions of biodegradability and
weight fractions are reviewed by EPA (1979) and EMCON (1980). A summary of
theoretical gas yields predicted by several authors is given in Table 37.
TABLE 37. SUMMARY OF THEORETICAL GAS YIELDS FROM MUNICIPAL
SOLID WASTE REPORTED IN THE LITERATURE
Reference
5
4
86
21
116
Method
MSW (Overall)
MSW (Overall)
MSW (Overall)
MSW (Overall)
Weighted
Total Gas Yield
Prediction,
m3/kg Dry Waste
0.41
0.42
0.46
0.45
0.35
Methane Yield
Prediction,
nrVkg Dry Waste
0.24
0.21
0.25
0.23
0.17
61
199
191
Biodegradability
Weighted
Biodegradability
Weighted
Biodegradability
Weighted
B iodegradab ili ty
0.19
0.25
0.12
0.09
0.12
0.06
103
-------
These methods and the yields summarized in Table 37 are, at best, rough
estimates of the potential gas production from landfill biodegradation of
organic refuse constituents. As demonstrated below, they fail to include the
influences of numerous factors such as the extent of aerobic and anaerobic
decomposition, nutrient limitations, biological inhibition, and
physical-chemical interactions which will generally serve to decrease the
predicted methane yields. Moreover, these assumptions project a 100$ recovery
of gases produced, which on full-scale is impractical due to the high
potential for uncontrolled gas migration, escape and entrapment.
Empirical Gas Yield Projections
Field and laboratory observations serve as the best indicator of actual
gas yields from sanitary landfills. Gas yields reported in the literature for
lysimeter and field studies are summarized in Table 38. As shown in the
table, gas yields reported for small lysimeters were generally higher than
those reported for larger landfill simulators. Although these results may be
expected due to the greater potential on full-scale for localization of
activity (microenvironment isolation), gas entrapment and leaks, moisture
short-circuiting, etc., the data available to date are insufficient to
quantify these factors. Therefore, gas yields reported for lysimeters should
be used with caution when extrapolating for full-scale predictions. Data from
full-scale operations would be the best indicator, but availability of such
data is still limited. Moreover, older landfills which may have reached
maturation have not been routinely examined with respect to refuse
characteristics and/or gas yields. Newer landfills have yet to reach
maturation so that even with routine analysis, total gas yields cannot be
formulated and/or substantiated. Such data acquisition is also impeded by the
variety and inherent uncertainty of gas collection methods employed at various
sites. This problem is further magnified by a lack of understanding of the
biochemical interactions occurring within the landfill and the absence of
uniform and reliable data collection protocols.
The experimental data presented in Table 38 confirm the impracticality of
utilizing theoretical predictions of gas yield. The yields determined
experimentally were generally on the order of 10% (or less) of the theoretical
predictions presented in Table 37.
Gas Production Rate Predictions
Several authors have developed mathematical models in attempts to
describe gas production rates at landfills (see review by EMCON, 1980).
However, these models are basically curve fitting techniques for which
sufficient data are presently not available. Therefore, current gas
production rate predictions are generally obtained by comparing overall gas
yields from laboratory studies to the total "stabilization" time, by
installing observation wells (EMCON, 1980; DOE, 1981), or by literature
comparison. A summary of gas production rate data reported in the literature
is presented in Table 39 for small-scale studies, and in Table 40 for
full-scale operations.
The variations in lab-scale data are due to differences in waste types,
moisture content and application rates, buffer, nutrients, etc.; they also
reflect the discontinuities to be expected at full-scale installations.
Moreover, gas production rates will vary with time as the organic content
leached from the refuse in the landfill decreases due to biodegradation and
104
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TABLE 38. SUMMARY OF EXPERIMENTAL OBSERVATIONS OF GAS
PRODUCTION FROM MUNICIPAL SOLID WASTE
Reference
Experimental
Conditions
Gas Yields,
m3(STP)/kg (dry)
Total
225
180
181
10
1 .2m dia. x 2.3m deep sealed
lysimeters; simulated pre-
cipitation applied; 7-20°C;
pH 5.6 to 5.9; 190-day study 0.006
municipal refuse wetted with
digester supernatant 0.013
2.4m dia. x 8.5m underground
steel tank; 19-49°C; 900-day
study 0.004
carboys filled with 34.5 kg (wet)
of mixture of refuse, moisture,
sewage sludge buffer; 37°C;
670-day study 0.25
0.001
0.13
71
279,
280
211
29
208-liter sealed steel lysimeters;
15-20°C; 300-day study
1.8m dia. x 3-7m deep steel
lysimeters; simulated annual pre-
cipitation/infiltration; 2100-day
study
3m square x 5.2m deep lysimeters;
simulated annual rainfall; shredded
refuse; 699-day study
19-liter lysimeters; shredded waste
inoculated with sewage sludge;
410-day study
0.001-
0.018
0.003-
0.018
0.007
0.001
0.23
0.001
0.004
0.001
0.14
washout. In most cases, gas production will remain low for any active
landfill area until the first three phases of landfill stabilization depicted
in Figure 1 have been completed. Thereafter, gas production rates will
increase rapidly to a maximum or peak value during active methanogenic
stabilization (Phase IV). For each landfill section, the majority of the
methane generated will be released during a relatively short period, i.e., 10
to 20? of the total time required for stabilization, unless restricted by the
105
-------
TABLE 39. SUMMARY OF EXPERIMENTAL OBSERVATIONS OF GAS PRODUCTION
RATES IN SMALL-SCALE LANDFILL SIMULATORS
Reference
225
10
71
211
29
Total Gas Production Rate,
Average
0.007
0.13
0.0001-0.013
0.002
0.025-0.488
m^/kg-yr
Maximum
0.007
0.44
0.055
0.030
3.16
factors indicated previously. After the available biodegradable substrate is
exhausted, gas production rates will rapidly decline and gas collection for
recovery from that landfill would correspondingly become unattractive.
Recognition of the sequence of events leading to and controlling high gas
(methane) production rates is paramount in planning and designing for
efficient and cost effective gas management strategies. These strategies
should include consideration of reusable and/or mobile gas collection/recovery
appurtenances which could be moved sequentially in a scheduled fashion as the
landfill is developed. Such preconceived temporal and spatial planning of gas
removal/recovery/utilization facilities within a landfill stabilization
perspective has not yet been established as general procedure.
In spite of the previously outlined uncertainties associated with the
results of landfill studies, the landfill lysimeter and full-scale data
presented in Tables 39 and 40, respectively, tend to correlate fairly well.
Simulator studies have generally yielded gas production rates on the order of
0.002-0.13 m3/kg-yr, while full-scale studies have exhibited a range of
0.001-0.008 m3/kg-yr. The higher gas production rates were generally reported
for studies using buffer and moisture controls. Therefore, gas production
rates of 0.005 to 0.008 m3/kg dry waste per year may be anticipated from
controlled landfills within a few years of refuse placement. However, it
should be recognized that higher gas production rates are probably associated
with those portions of a landfill that have aged to the active methanogenic
phase of landfill stabilization.
Gas Composition
Landfill gases are typically 40 to 60% methane, with the remaining volume
comprised primarily of carbon dioxide and 1 or 2% (total) of other
miscellaneous inorganic gases and organic vapors. Bench-scale studies with
leachate recirculation have achieved methane contents as high as 70%, although
methane contents this high have not been common on full-scale. Table 41
provides a summary of gas composition (% CHi|, C02, N2, 02) for a number of
full-scale facilities reviewed by EMCON (1980). Additional data on trace
constituents are provided by EMCON (1977) and Lofy (1981) as summarized in
Table 42. The data presented indicate that organic and inorganic sulfur
106
-------
TABLE HO. ON-LINE LANDFILL GAS RECOVERY FACILITIES IN U.S.
Landfill
Landfill Depth.
and
Location
m
Acme, CA 21.3
Azusa, CA 51 .8
Bradley 30.1-36.5
Sanitary
Landfill, CA
Cinnaminson, 18.3
CA
City of 39.6
Industry, CA
Davis Street, 24.1
CA
Industry 9.11-33.5
Hills, CA
North Valley, 76.2
CA
Palos Verdes, 15.7-76.2
CA
Mountain 12.2
View, CA
Fresh Kills, 15.2*
CA
Sheldon-Arleta, 36
Sun Valley, CA
Puente Hills,
CA
Monterey Park, 75.7
CA
Duarte, CA
Scholl Canyon, 26.0
Glendale, CA
Characteristics
Area,
x106m2
0.50
1 0.30
0.26
0.26
1.21
0.78
2.1
0.17
0.17
1.011
1.61"
0.16
-
0.50
0.13
0.18
MSW in
Place,
x106kg
2,503.8
6,350.3
8,161.6
2,267.9
6.350.3
5,252.6
3,229.5
1,535.9
18,113.7
3,628
68,038.8
5,150
-
20,090
1 ,820
1,500
No. of
Gas Wells
12
11
39
29
30
20
30
5
12
33
123
11
87
56
33
27
Depth
of
Wells,
m
21.3
30.1-18.7
18.2-23.5
15.2-18.2
39.6
18.2
12.9-22.8
30.1
15.7
13.3
16.7
21-33
36
-
18
25.7-56.1
Gas
LFG
Recovered,
x106m3/day
0.056
0.120
0.076
0.019
0.111
0.081
0.006
0.031
0.051
0.085
0.282
0.100
0.250
0.220
0.030
0.017
Recovery Program
Rate of
Gas
Production
m3/kg-yr
0.008
0.002
0.003
0.003
0.008
0.005
-
0.002
0.001
0.008
0.001
0.014
_
0.001
0.006
0.006
LSF Sold
to User,
x106m3/day
0.056
0.014
0.076
0.019
0.07
0.084
-
0.031
0.021
0.014
0.141
0.10
0.16
0.22
-
_
Heat
Content
of
Delivered,
kJ/m3
13.1
13.4
12.1
14.7-16.1
26.8
13.4
13.4
26.8
26.8
-
26.8
13.1
13.4
26.8
-
_
Type of Gas
Treatment
Proprietory
Triethylene
glycol
Dehydration
Solids Removal
Minimal; water
separators to
remove moisture
Selexol and
Proprietory
Proprietory
None
Triethylene
glycol , molecu-
lar sieves
Triethylene
glycol, molecu-
lar sieves
Glycol, alumina
gel, molecular
sieves, acti-
vated carbon
Selexol and
Dehydration
Not available
Chilling,
Selexol, other
Proprietory
Not available
Proprietory
Compiled from EPA (1979), USDOE (1981), Campbell (1981), and Tour Fact Sheets from the Sixth International GRCDA Landfill Gas
Symposium, March (1983).
*Depth of Landfill In the Project area "Project Area. Total Area - 6.41 x 106m2
107
-------
TABLE *1. SUMMARY OF LANDFILL GAS COMPOSITION AT
FULL-SCALE LANDFILLS
Landfill Site
Azuza Western, Azuza, CA
Bradley, Los Angeles, CA
Central Disposal Site
Sonoma Co. , CA
O.R.O.W.S., Norristown, PA
Hewitt, Los Angeles, CA
Mountain View,
Mountain View, CA
Palos Verdes,
Rolling Hills, CA
P.I.I., Denver , CO
Scholl Canyon, Glendale, CA
Shel ton-Arleta
Los Angeles, CA
CHu
50
50
50
46
45
44
53
15
HO
55
Gas Composition, %
CO? Up
50
50
50
53 1
55
34 21
43 3
55
51 7
45
0,
—
~
—
—
1
~
—
2
—
After EMCON, 1980.
TABLE H2. TRACE CONSTITUENTS DETECTED IN
LANDFILL GASES
Constituent
Hydrogen Sulf ide
Mercaptan Sulfur
Sulf ides
Disulfides and Residuals
Acetic Acid
Propionic Acid
Butyric Acid
Valeric Acid
Caproic Acid
H20 Vapor
•U i ffr*ain kff
on "? • 0-0055 ^3
1 00 scf op
EMCON , 1 977
(Mountain View)
(grains/1 OOscf )*
0.40-0.91
0.0 -0.33
0.41-0.80
0.93-1.65
—
—
—
—
—
—
••Reported as organic
LOFl, 19B1
(Scholl Canyon)
(grains/1 OOscf )
<0.01
0.01**
—
—
0.27
0.41
0.39
0.13
0.08
123.0
sulfur compounds
108
-------
TABLE 43- REPRESENTATIVE LIST OF ORGANIC COMPOUNDS
IDENTIFIED IN LANDFILL GAS
*Pentane
*Dichloromethane
*Hexane
*Iso-octane
*Methylbenzene
*Tetrachloroethene
*Ethylbenzene
*Nonane
*Propylbenzene
Tetramethylhexane
Methylpentane
DimethyIpentane
Methylhexane
Heptane
Trimethylcyclopentane
DimethyIhexane
Dimethylcyclohexane
Octane
DimethyIhexene
Dimethylcyclohexane
Trimethylcyclohexane
Cyclohexyl-eicosane
Ethylpentene
Ethylmethylbutene
Tetramethylpentane
Diethylcyclohexane
Tetramethylbutane
Methylnonene
Tetramethylcyclopentane
Ethylmethylcyclohexane
Methylpropylpentanol
Dichlorofluoromethane
Heptanol
Decane
Decahydronaphthalene
*Dichloroethylene
*Dichloroethane
*Benzene
*Trichloroethylene
*Trichlorethane
*Chlorobenzene
Bimethylbenzene
*Isopropylbenzene
*Napthalene
Methylpentylhydroperoxide
Methylcyclopentane
Hexene
Dime thyIcyclopentane
Cycloheptane
Tetrahydrodimethylfuran
Methylheptane
EthylmethyIcyclopentane
Tetramethylcyclopentane
DimethyIheptane
Ethylcyclohexane
Ethylmethylcyclohexane
Methylpropylpentanol
Iso-octanol
Octahydromethylpentalene
Dimethyl(methylpropyl)cyclohexane
EthylmethyIheptane
Methylene-butanediol
Tetramethylhexene
Methylpropylpentanol
Nonyne
Methyl (methylethenyD-cyclohexene
Hexadiene
Ethylbutanol
Butycyclohexane
After GRI, 1982
*Further quantitative data on these compounds is provided in Table
109
-------
TABLE 11. SUMMARY OF MAXIMUM AND AVERAGE VOLATILE ORGANIC COMPOUND CONCENTRATIONS (PPM BY VOLUME) FOUND IN
FULL-SCALE LANDFILL AND LANDFILL SIMULATOR GASES
Full-Scale Landfill Gases*
Compound
Pentane
1 , 1 -dichloroethylene
Dichlorome thane
1 ,2-dichloroethylene
1 , 1 -dichloroe thane
Hexane
Benzene
Iso-octane
Trichloroethylene
Methylbenzene
1 ,1 ,2-trichloroethane
Tetrachloroethylene
Chlorobenzene
Ethylbenzene
m,p-xylene
o-xylene
Nonane
Isopropylbenzene
Propylbenzene
Napthalene
Inlet to
Max
5.0
1 .1
12.0
3.6
7.5
28.0
23-0
1.1
8.1
210.0
0.1
35.0
11 .0
51.0
91 .0
25.0
12.0
28.0
3-5
0.1
Landfill Simulators**
Treatment Product Gas" Surface
Mean
0.1
0.1
0.9
0.7
0.1
1.8
1 .7
0.1
0.8
9.6
<0.01
1.3
0.1
3.0
3-7
1.3
0.9
0.7
0.1
<0.01
0.8
0.2
0.6
0.8
0.2
8.3
0.7
0.7
0.7
2.9
<0.01
0.8
0.1
1 .1
1.2
0.1
0.7
0.5
0.2
SO.QI
0.3
<0.01
0.2
0.2
0.3
0.3
0.3
1 .0
1.0
0.3
NDd
0.3
ND
0.2
0.8
0.1
0.2
<0.01
<0.01
ND
Max
ND
0.55
1 .57
3.26
2.08
97.00
12.80
8.16
1.76
6.35
ND
0.20
0.21
1.01
1.10
2.90
6.82
t.22
0.17
0.81
Mean
ND
0.12
0.19
0.21
0.33
8.83
1.61
0.77
0.37
1.92
ND
0.03
0.01
0.57
0.66
0.50
1.28
0.15
0.05
0.11
TLVD
600
5
100
200
200
50
10
300
NR
100
10
NR
75
100
100
100
200
50
NR
10
Regulatory Levels
STELC
750
20
500
250
250
NRe
25
375
NR
150
20
NR
NR
125
150
150
250
75
NR
15
NYSAAL*
NR
0.02
0.33
NR
NR
NR
0.03
NR
0.17
2.00
0.03
0.17
0.33
0.25
0.33
0.33
NR
NR
NR
0.03
OSHA/NIOSH8
PEL/TWA
1000
5
500
200
100
500
1
NR
100
200
10
100
100
75
100
100
200
50
NR
10
IDLH
5000
NR
5000
1000
1000
5000
2000
NR
1000
2000
500
500
2000
2100
10000
10000
NR
8000
NR
500
alncluding products from a high- and a medium-BTU gas treatment system
bThreshhold Limit Value - American Conference of Governmental Industrial Hygenists, Inc., ACGIG, 1982*
°Short Term Exposure Limit - ACGIH, 1982*
dND = not detected
eNR - not reported
fNew York State Acceptable Ambient Levels for toxic air contaminants as presented in Air Guide #1, NYSDEC, December 15, 1983.**
Soccupational Safety and Health Administration and National Institute for Occupational Safety:
PEL = Permissible Exposure Level averaged over an 8-hour work shift;
IDLH = Maximum Level Immediately Dangerous to Life or Health, i.e., from which one could escape within 30 minutes without
irreversible health effects.**
*After GRI (1982)
**After Vogt and Walsh (1981)
-------
compounds may be common trace gaseous constituents and that volatile organic
acids were also detected.
Investigations of trace organics in landfill gases have been performed by
ESCOR, Inc. for the Gas Research Institute (GRI, 1982). Sixty-nine individual
organic compounds were identified by two independent laboratories as
summarized in Table 43. Twenty compounds were targeted for further
quantitative study and a summary of ESCOR1s findings for inlet, processed, and
surface gases are compared to the American Conference of Governmental
Industrial Hygenists' Threshold Limit Values (TLV) and Short-Term Exposure
Limits (STEL), New York State Acceptable Ambient Levels and OSHA/NIOSH limits
in Table 44.
Similar studies performed for GRI on gases emanating from landfill
simulators containing known quantities of co-disposed industrial waste and
priority pollutants have been reported (Vogt and Walsh, 1984). The results of
these studies are also presented in Table 44.
COLLECTION AND TREATMENT OF LANDFILL GASES
The equipment required and generally used to collect and treat landfill
gases will depend upon the intended use of the gas. Product gases may be
withdrawn to prevent migration and simply flared or exhausted to the
atmosphere, withdrawn and sold to a consumer directly, used on-site with or
without prior treatment, or treated and sold to a consumer as pipeline quality
gas.
Landfill Gas Collection—
Gas collection systems employed in practice may consist of simple
ventilation and/or flaring systems coupled with shallow trench induced exhaust
networks intended primarily for migration control, and/or perforated pipe well
matrices placed either vertically or horizonally. The latter are generally
used for energy recovery and are reviewed in more detail by Esmaili (1975),
Moore and Lynch (1977), Stone (1978), EPA (1979), EMCON (1980) and USDOE (1981)
Induced exhaust well systems are the most popular for energy recovery.
These systems will generally encompass extraction equipment such as transport
and well piping, backfill gravel, blowers and compressors, metering equipment,
and monitoring equipment. Well or trench systems generally incorporate
perforated PVC pipe, although polyethylene or fiberglass pipes can also be
used. The advantages and disadvantages of these are summarized in Table 45.
Networks of header pipes are generally connected to vertical wells which are
spaced so that their radii of influence overlap; the radius of influence of
wells depend on their depth and the pumping rate (Esmaili, 1975; Moore and
Lynch, 1977); Constable, et_ al., 1979), as well as the degree of compaction,
i.e., refuse and cover permeability.
Vertical wells are generally placed to a depth approaching the total
refuse depth depending on the existing volume of leachate. The lower half or
more of the well piping is usually perforated. Gravel backfill is used for
the perforated section, while the upper portion of the boreholes are
backfilled with soil to help prevent air intrusion.
Ill
-------
TABLE 45. ADVANTAGES AND DISADVANTAGES OF GAS COLLECTION
PIPING MATERIALS
PIPING MATERIAL
Polyvinyl chloride (PVC)
Polyethylene (PE)
ADVANTAGES
Lightweight, easily
installed, corrosion
resistant, low cost.
Corrosion resistant;
can withstand high
bending loads without
shear.
DISADVANTAGES
Becomes brittle'when
exposed to sunlight for
extended periods; fails
under high differential
shear loading.
Requires special welding
equipment for installation;
higher cost than PVC.
Fiberglass
Lightweight
High cost; special sealing
required to prevent
leachate intrusion.
Steel
Can withstand high
bending loads without
shear.
Subject to corrosion
from acids; special welding
equipment required; high
cost.
After EMCON 1980; Street, 1983; Petro, 1983.
Perforated pipe may also be placed horizonally in a network of shallow
trenches, but these must be well sealed at the top to prevent introduction of
air. In some cases, shallow gravel-filled trenches have been used without
perforated pipe, with the trench serving as the collection system. The
success of these systems is highly dependent upon providing an impermeable
layer, perhaps a synthetic liner, to prevent air introduction from the surface.
The economics of gas collection and liner systems are addressed in detail by
EPA (1979).
Centrifugal blowers are often recommended for low vacuum pressures [up to
16 cm (40 in.) water]. These blowers are easily throttled throughout their
operating range, although spark-proof varieties are required and are available
from several manufactures. For higher pressures, regenerative blowers may be
desired. Rotary lobe compressors are generally recommended for landfill gas
applications requiring gas pressures in excess of 1425 to 2138 kg/m^ (2-3
psi).
Gas flow measurement in landfills may be accomplished in gas collection
piping using pitot tubes, venturi and orifice plate flow meters, and turbine
meters. However, such flow measurements may be difficult to perform
accurately and a combination of the above methods, coupled with frequent
cross-calibrations of these, is highly recommended.
112
-------
Landfill Gas Treatment—
As noted previously, the intended use of the gas produced at a particular
landfill will dictate the extent of treatment required. Raw landfill gases
typically have a low heating value due to the dilution of methane with CC>2,
N2, and possibly 03. They will likely contain troublesome constituents such
as water and hydrogen sulfide. Trace levels of hydrocarbons are also of
concern, although these may be expected to oxidize rapidly when the gas is
combusted.
Treatment technologies available for the production of either medium BTU
(13-15 kJ/m3; 500-600 BTU/SCF) or pipeline (26 kJ/m3; 1000+ BTU/SCF) gases are
aptly reviewed by EPA (1979), Ashare (1981) and Love (1983). An indication of
treatment processes used at currently operating full-scale landfills is
presented in Table 40.
Medium BTU Gases—Medium BTU gas is generally produced from raw landfill
gas by removing th-,, water vapor and possibly hydrogen sulfide. Condensate and
particulates are first removed in a gas/liquid separator; if further water
vapor removal is desired, the gas is compressed and cooled prior to being
dehydrated using glycol or triethylene glycol. As indicated in Table 46,
silica gel, alumina, or molecular sieves may also serve to absorb excess water
vapor, although these techniques are generally too expensive for large
applications. Glycol absorption is generally the method of choice.
Hydrogen sulfide may be removed using a number of organic solvent
absorbents, many of which will absorb 003. f^S can be selectively removed
using dry oxidation processes which are also selective for mercaptans, carbon
oxysulfide, carbon disulfide and thiophenes. These processes use intermediate
oxygen carriers (such as wood shavings) which are nonregenerative and require
periodic recharging. This has led to the development of aqueous hydrogen
sulfide oxidation methods which utilize solutions or suspensions of sodium
carbonates, potassium carbonates, heavy metals (arsenic or iron) or quinones.
Continuous operations with recovery of elemental sulfur of high purity are
usually possible. However, since these latter processes may be prohibitively
expensive for most medium BTU gas applications, solvent methods are generally
preferred.
High BTU (Pipeline) Gases—Landfill gas must have a high heat value and a
high degree of purity to be sold and mixed with pipeline quality natural gas.
Water must be removed to less than 0.0001 kg/m3 «7 Ibs/MMSCF), hydrogen
sulfide to levels ranging from 4 to 80 kg/nP or less, and carbon dioxide and
nitrogen to sufficiently low levels so that 1000+ BTU/SCF (>26 kJ/m3) are
obtained.
Water can be removed by the previously mentioned silicate absorption
processes, or by absorption with glycols or Selexol, a proprietary solvent
which also absorbs heavy hydrocarbons. Alternatively, water may be removed by
chilling to approximately 35°F (2°C). Heavy hydrocarbons may be removed using
absorption with lean oils or ethylene glycol, adsorbed using activated carbon,
or by a combination of absorption followed by adsorption.
Carbon dioxide can be removed using aqueous phase organic solvents,
alkaline salt solutions or alkanolamines as indicated in Table 46. Solid bed
adsorption using activated carbon or molecular sieves (silicates) is also
113
-------
TABLE 46. SUMMARY OF GAS TREATMENT METHODS AVAILABLE FOR THE
REMOVAL OF WATER, HYDROCARBONS, CO?, and H?S
TARGET
COMPOUND
TREATMENT
PROCESS
TYPE
TREATMENT
PROCESS ALTERNATIVES
AVAILABLE
Water
Adsorption
Absorption
Refrigeration
1. Silica gel,
2. Molecular sieves, and
3. Alumina
*1. Ethylene glycol (at low
temperature ,-20°F)
2. Selexol
1 . Chilling to 35°C
Hydrocarbons
Adsorption
Absorption
Combination
1. Activated carbon
1. Lean oil absorption,
2. Ethylene glycol, and
3. Selexol
all at low temperatures
(-20°F, -29°C)
*1. Refrigeration with
Ethylene glycol plus
activated carbon
adsorption
C02 and
Absorption
Adsorption
Membrane
Separation
1. Organic Solvents
Selexol
Fluor
Rectisol
2. Alkaline Salt Solu-
tions
Hot Potassium and in-
hibited hot potassium
(Benefield and
Catacarb Processes)
3. Alkanolamines
mono,-di-tri-
ethanol amines;
diglycolamines;
*UCARSOL-CR (proprie-
tary chemical)
1. Molecular Sieves
2. Activated Carbon
1. Hollow Fiber Membrane
'Designates method of choice (after Love, 1983).
114
-------
possible, although extreme caution is needed to prevent sieve contamination by
water, butanes and heavier compounds. Carbon dioxide may be selectively
removed by reverse osmosis processes. However, membrane processes require
extensive pretreatment of product gases to avoid scaling or fouling of the
membrane surface.
Adsorption processes (Table 46) are generally preferred for CC>2 and H2S
removal. Organic solvents can accommodate high acid gas loadings and require
relatively low recirculation rates compared with other methods. Each of these
methods have their own advantages and disadvantages, as reviewed by EPA (1979)
and Love (1983). Selexol also absorbs heavy organics and water, thereby
decreasing its overall affinity for CC^. Moreover, C02 is absorbed only at
high pressure and low temperature, therefore, refrigeration is required. The
same is true for Rectisol, which operates best at -80°F (-63°C). Alkaline
salt processes generally require high pressures [142,560 kg/m2 (200 psig]. In
these processes, hot potassium carbonates or sodium carbonates (sometimes
coupled with proprietary inhibitors as in the Benefield and Catacarb
processes) serve as buffers to react with acid gases.
Alkanolamine absorption methods have a widespread acceptance for C02
removal from natural gas; monoethanol (MEA) and diethanolamines (DEA) have
also been successfully applied. MEA is corrosive at *\9% concentrations,
whereas, DEA may be used at solution strengths approaching 35% without undue
corrosion. Therefore, DEA, which does not absorb heavy hydrocarbons and,
therefore, selectively removes COg, is the generally preferred method of C02
removal.
Nitrogen may be removed by liquifying the methane fraction of landfill
gas by mechanical refrigeration, leaving the other gas fractions to be
exhausted. Considerable refrigeration equipment is required for this process
and it is usually prohibitively costly. The best practice is to avoid drawing
air into the landfill to the greatest extent possible, thereby minimizing the
nitrogen content.
Economics—
The economics of implementing the preceding gas collection and treatment
alternatives have been reviewed in detail by others (EPA, 1979). In this
review, four gas treatment alternatives were considered including dehydration,
dehydration plus CC>2 removal, dehydration plus CC>2 and Ng removal, and
dehydration plus CC>2 removal and propane blending. Each alternative was also
analyzed at several gas production rates as summarized in Table 47. Scrutiny
of these data indicates the relative increased costs associated with N2
removal and the importance of minimizing the introduction of air during gas
extraction from the landfill. Based upon an energy value equivalent to
revenue of $1.9/mmkJ (1979 dollars), the probable payback periods associated
with each alternative ranged from <3 years (Alternative I) to 10 to 30 years
(Alternatives II and IV) and >30 years (Alternative III).
115
-------
TABLE 47. RELATIVE ECONOMICS OF SEVERAL GAS TREATMENT ALTERNATIVES
Treatment Alternative
Cost
Item
Production Rate, std m^/min
Alternative I.
Dehydration, compression
INPUT 13-74 34.69 69.38
OUTPUT 13.03 32.85 65.70
Capital Cost, M$
Annual Operating Cost;
Annual Energy Output,
Energy Cost, $/MM KJ
, M$
109 KJ
636
185
116
1.6
957
273
291
0.9
1388
. 387
581
0.7
Alternative II.
Dehydration and C02
removal
INPUT 47.29 94.45 141.60
OUTPUT 13-74 27.47 42.34
Capital Cost, M$
Annual Operating Cost,
Annual Energy Output,
Energy Cost, $/MM KJ
, M$
109 KJ
1740
359
231
1.6
2772
537
463
1 .2
3792
702
711
1 .0
Alternative III.
Dehydration plus C02
removal and N2 removal
INPUT 47.29 94.45 141.60
OUTPUT 11.89 24.64 40.36
Capital Cost, M$
Annual Operating Cost,
Annual Energy Output,
Energy Cost, $/MM KJ
M$
109 KJ
2612
555
203
2.7
4038
807
424
1 .9
5450
1051
695
1 .5
Alternative IV.
Dehydration plus C02
removal and propane
blending
INPUT 47.29 94.45 141.60
OUTPUT 14.22 28.43 43-70
Capital Cost, M$ 1802 2847 3877
Annual Operating Cost, M$ 463 730 992
Annual Energy Production, 109 KJ 251 503 773
Energy Cost, $/MM KJ 1.8 1.5 1.3
116
-------
SECTION 8
LEACHATE AND SOIL INTERACTIONS
GENERAL PERSPECTIVE
As previously noted, one of the primary concerns associated with landfill
disposal of municipal and industrial wastes centers on the formation and
migration of leachate into the surrounding environment. Presently, the
installation of low permeability clay and/or synthetic'liners is mandated to
deter this migration and its potential deleterious effects. However, many
landfills are in existence which have been constructed without the benefit of
such liners. Moreover, clay liners are known to be permeable, and recent
evidence has shown the same to be true for synthetic liners (Haxo, 1984;
Giroud, 1984). Therefore, the purpose of this section is to introduce
literature pertinent to the migration of leachates and their subsequent
interactions with surrounding native soils and to use it to evaluate the
associated implications in relation to soil types present and the necessity
and/or effectiveness of available remedial measures. It is not intended here
to provide an exhaustive review, but to expose such environmental impacts
should leachate (or gas) migration occur.
Basic research on soil/leachate interactions has been ongoing in the U.S.
(Roulier, 1977; Fuller, 1977; Copenhauer and Wilkinson, 1979), Canada
(Phillips and Nathawani, 1976) and Europe (Sumner, 1978)'since the early
1970's. The scope of this research has been extremely broad in nature due to
the wide variability in native soil types and leachate characteristics. To
provide for a more focused discussion, the review presented here will be
limited to soils comprised of mixtures of sand, silt and clays, with the clays
consisting of kaolinitic, illitic, and montmorillonitic minerals. Bentonitic
clays were not considered, since these are specifically used in slurry wall
systems and the substantial amount of information available on the interaction
between a variety of toxic chemicals and slurry walls and slurry trenches is
beyond the scope of this review. Nevertheless, since bentonite is in reality
a special type of montmorillonite, many of the results and conclusions of this
section may be extended to include bentonite slurries.
Soils used for experimentation basically fall into two categories;
defined mixtures of different proportions of clay minerals and sands, and
natural soils which were considered representative of a particular landfill
site. While the former offer valuable insight into specific physico-chemical
interactive properties of individual materials and mixtures thereof, the
latter are more relevant to actual engineering applications. Recognizing that
results from a particular site may not extrapolate well to other landfill
sites, the use of defined materials may be preferred to provide boundary
expectations of the response of different soil types to applied leachates.
117
-------
Studies on the interactions of soils with leachates can be broadly
classified into four topical areas, each focused on the fate or biological
removal processes, as associated with heavy metals, pesticides, organics and
selected toxic substances. Accordingly, the following discussion is organized
to address each of these areas in turn, followed by a review of attempts at
modeling leachate and soil interactions, and a summary and synthesis of
recommendations for future research.
Heavy Metal Attenuation
A considerable number of studies have been performed to evaluate
interactions between heavy metals in leachate and soils. For the most part,
emphasis has been placed on the fates of cadmium (Hem, t972; Jurinak and
Sanitillan-Medrano, 1971*; Weber and Posselt, 1975; Stevenson, 1976; Gibb and
Cartwright, 1976; Fuller, 1977, 1978; Garcia-Miragaya and Page, 1977; Doner,
1978; Fuller, et_ al., 1981), nickel (Fuller, 1977; Doner, 1978), lead
(Santillan-Medrano and Jurinak, 1976; Stevenson, 1976; Zimdahl and Skogerbee,
1977), zinc (Hem, 1972; Fuller, 1977; Fuller, et_ al_., 1981) and copper
(Stevenson, 1976; Doner, 1978).
Results from these studies provide substantive evidence that these metals
are mobile in natural soils, even in those soils exhibiting low permeability.
The relative mobility of these metals has been found to be a function of
several factors including pH, soil types, total organic carbon content of soil
organic matter, nature and concentration of metal ions, and the aerobicity (or
anaerobicity) of the soil. In general, as pH decreases due to acidic
conditions imposed by organic acid formation, metals become more mobile (Gibb
and Cartwright, 1976; Harkins, 1977; Theis, 1976, 1977; Griffin and Shimp,
1976; Griffin, _et al., 1977; Frost and Griffin, 1977; Zimdahl and Skogerbee,
1977). Korte, et. _al_., (1975) reported that upon application of synthetic
acidic leachate to typical natural soils, metals were eluted in the following
order: Mn, Co, Ni, Zn, Cu, Cr, Pb, Cd. Using neutral leachates, Farquhar
(1977) noted that all trace elements studied were adsorbed to some extent,
with Zn and Fe being most strongly attenuated, and Ca and Mn being most mobile.
Roulier (1977) reported that Cr, Hg, and Ni were extremely mobile in a wide
variety of soils. Niebla, _et al_., (1976) reported Hg to be more mobile in
leachate than in'water, while Griffift and Shimp (1976, 1978) indicated that Hg
in leachates was significantly attenuated by clay materials. Gibb and
Cartwright (1976), Griffin and Shimp (1976), and Griffin, _et al_., (1977) all
reported Cr to be particularly mobile at neutral pH values, since the Cr"1""
form is more mobile than Cr+3. Therefore, acidic (or "younger") leachates
show less Cr mobility in electronegative clay soils than do the less acidic
leachates produced during and after the active methanogenic phases of
stabilization. Niebla, _et Q., (1976) noted similar observations with respect
to Hg attenuation.
The composition of the leachate (conductivity, total iron, total metals,
organics) and the composition and nature of the soil (% clays, pore size
distribution, permeability) also play a major role in determining metal
mobility (Korte, et al., 1975; Fuller, 1977; Fuller, et al., 1976, 1981).
Griffin and Shimp (1976, 1978) suggest that the clay content is important due
to its cation exchange properties, and emphasize that the cation exchange
capacity (CEC) is more important than total particle surface area. Fuller, et
al., (1981) support this notion, and correlate the high mobility of Cr and Se
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to their low potentials for cationic exchange. In this regard, the presence
of high levels of salts, iron, and organics (TOC) will enhance the migration
of metals due to a more rapid exhaustion of the native CEC. Highly permeable
soils will also encourage greater metal migration due to higher mass flows and
reduced contact opportunity, resulting in a lower potential for occurrence of
clay precipitation reactions.
Microbial activity can influence metal migration by affecting several of
the previously mentioned attenuation mechanisms. Many biochemicals
synthesized by microorganisms, including amino acids and the simple aliphatic
acids, form soluble complexes with metal ions (Stevenson, 1982). Most
important is probably the effect of changing pH; first as a result of
acidification and subsequent methanogenesis, secondly as a result of
competition for adsorption sites and lastly by a restriction of flow due to
clogging of soil pores. Further research on relationships between polyvalent
cations and the organic components of soil is warranted, since soil organic
constituents can form both soluble and insoluble complexes with metal ions.
Pesticide Migration
Pesticide attenuation in landfills arises from two major mechanisms,
i.e., microbial degradation and adsorption. Newman and Downing (1958) and
Davidson, ej^ al_. (1976, 1978, 1980) have studied the problems of pesticide
disposal and have concluded that biological degradation represents the major
removal mechanism in soils. The degradability of particular pesticides such
as atrazine (Cole, 1976; Dao and Lavy, 1978), triazine (Kaiser, et_ al_., 1970)
and parathion (Wolfe, et_ a.1., 1973; Katan, at al., 1976) as well as
combinations of pesticides (Hubbel, e_t al_., 1973) have also been studied. In
general, biological degradabilities varied with soil type and pesticide
concentration and although a long lag period was typically observed
(especially at high concentrations), in almost all cases the pesticide was
eventually degraded.
Partial microbial degradation of many pesticides results in the formation
of chemically reactive intermediates. These intermediates can potentially
combine with the amino- or carbonyl-containing constituents of soil organic
matter. The immobilization of chloroanilines (liberated by partial
degradation of phenylamide herbicides) by soil organic matter has been
reported (Bartha, 1971; Bartha and Pramer, 1970; Hsu and Bartha, 1974). Acid
and base hydrolysis resulted in the partial'release of chloroanilines bound to
soil organic matters. Additionally, the soil-bound chloroanilines were found
to be resistant to microbial degradation (Hsu and Bartha, 197^).
The mechanisms for the adsorption of pesticides by soil organic matter
include ion exchange, protonation, H-bonding, van der Waal's forces, and
coordination through an attached metal ion. An excellent review of these
mechanisms has been provided by Stevenson (1982). In addition to these
mechanisms, nonpolar molecules are partitioned onto hydrophobia sites on soil
organic matter. Adsorption of pesticides onto different soil types (silts,
sands and clay) follows Freundlich isotherms. In addition, adsorption sites
become saturated at high pesticide concentrations and a uniform wetting front
will be absent (Rao, et al., 1979).
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In addition to other factors, the mobility of pesticides in the absence
of biological activity are related to their solubility. Most pesticides are
relatively insoluble in water, although they may be more soluble in acidic and
organic-containing leachates than in water. The interrelationships between
solubility, biodegradation, and adsorption in soils remain poorly understood
and, therefore, are requisite of further study.
Organics
Leachate-derived organics are important not only with regard to their
impact as contaminants, but also with respect to their effects on soil
structure and its resultant permeability. Early work on this topic, initiated
by Grim (1962), indicated that the solubility of clays in acids is dependent
upon several parameters including the nature and concentration of the organic
acid present, temperature and the duration of the acid/clay contact period.
The dissolution of aluminum and other ions was evident even under exposure to
relatively weak acids. These results were supported with experiments by
Anderson, et al. (1982) where a weak acid (acetic acid), a weak base
(aniline), and paint solvent were used. Tests with laboratory columns and
field cells (Brown and Anderson, 1980; Anderson, £t al., 1982; Brown, e_t al.,
1983) showed an initial decrease in permeability of the soil, followed by a
significant increase in permeability accompanied by a change in permeate color.
Dissolution of iron and calcium carbonate was suspected in all cases, and
"piping", the formation of a noticeable channel in the soil matrix, was
observed. Weak acids were shown to be more reactive than weak bases, although
weak bases were also responsible for alteration of the soil structure.
However, no piping was observed for weak base applications and an aggregated,
plate-like structure was noted following contact with weak base. While the
results of Anderson, e_t aJ.. (1982) showed significant changes in permeability
following the passing of only two pore volumes, contrasting results have been
presented by Lentz, e_t al. (1984), who observed no change in permeability
following passage of six pore volumes of strong acids or bases. Therefore,
unanimity of agreement in the published literature is not available and, of
more consequence, effects of aqueous mixtures at varying concentrations often
are not perceived due to experimental difficulties and/or the lack of true
simulation of landfill leachate contact opportunities.
Anderson, e_t al. (1982) also conducted similar tests with neutral polar
organics such as ethylene glycol, acetone, and methanol, and also with
neutral nonpolar organics such as xylene and heptane. In all cases,
significant changes in soil permeability were noted, often eventually
amounting to a two order of magnitude increase in permeability. Ethylene
glycol and acetone produced a pronounced initial decrease in permeability,
followed by a gradual increase in permeability. At the completion of each
test, the soil samples were inspected and structural changes ranging from
block-like structures to shrinkage cracks were observed. Re-introduction of
water did not result in reversion to the original permeability. Similar
results were noted by Foreman and Daniel (1984) and Acar, e_t al. (1984a,b).
However, Acar, ejt al. (1984b) found that the actual pore size distribution was
basically unaltered upon exposure to organics.
The mechanisms at work appear related to the type of clay present, the
dielectric constant and dipole moment of the permeant, and the initial degree
of soil saturation. Kaolinites showed the greatest resistance to permeability
120
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changes. Foreman and Daniel (1984) showed changes in both plasticity and
liquid limits when comparing Atterberg limits tests performed with methanol
and water. Kaolinitic samples exhibited decreased Atterberg limits, while
illitic and montmorillonitic samples showed increased limits. Although it
would be expected that liquid limit alterations may stem from changes in
interlayer spacings of clay particles, Anderson, et^ al_. (1982) showed no
interlayer spacing changes using X-ray diffraction techniques.
Future investigations into the interactions of organic materials,
especially in aqueous solutions of leachate-derived organics, seem warranted
in order that the interactive effects and mechanisms of permeability
alteration can be established with confidence. Additional studies are also
needed to address the long-term stability of altered clay structures and,
although soils such as used by Anderson, e_t a^. (1982) would generally be
accepted as liner materials based on permeability tests using water or calcium
sulfate solutions, they may well be rejected when applied to circumstances
where soil contact may occur. Data on these issues are only currently
becoming available.
Other Toxic Compounds
The majority of studies performed to evaluate leachate and soil
interactions have focused on heavy metals, pesticides, and organic solvents.
Several studies on the fate of other known toxic compounds such as arsenic,
cyanide, and halogenated organics are also available in the literature. Of
these, arsenic is apparently relatively immobile in soils, and its adsorption
increases with increasing soil concentrations of iron, iron oxides, and
aluminum (Fuller, _et _al_., 1980). Johnson and Lancione (1980) have shown that
complete immobilization of arsenic by fixation is feasible. In contrast,
cyanide is typically very mobile in soils and is apparently more mobile in
water than in "typical" leachates (Alesii and Fuller, 1976), thereby
indicating potential reactions between cyanide and other leachate components.
Microbial attack on cyanides was noted to be very dependent on cyanide
concentration, but was considered a potentially useful means of attenuation.
Moreover, cyanide was better attenuated at low pH and in the presence of iron
oxides and clays of lower electronegativity such as kaolinite or 1:1 lattice
clays.
Halogenated organics such as polychlorinated biphenyls (PCB's),
polybrominated biphenyls (PBB's), and hexachlorobenzenes (HCB's) are suspected
or known carcinogens which are nonpolar and, therefore, of low solubility in
water. In column tests using typical soils and leachates, these compounds
were found to be relatively immobile; their mobility was further related to
the clay content of the soil (Griffin, 1978; Griffin and Chou, 1980).
However, in the presence of organic solvents, PCB's and HCB's were shown to be
very mobile (Griffin and Chou, 1980). Unfortunately, these compounds are also
biologically refractory and tend to persist in soils, thereby presenting a
high potential for eventual migration. Adsorption of these compounds onto
clays follows linear Freundlich isotherms and increases as the organic content
(TOC) and the surface area of the clay increases (Griffin and Chian, 1980).
The more chlorinated biphenyls are less mobile than their less chlorinated
counterparts.
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Analytical Modeling of Leachate/Soil Interactions
A number of authors have developed mathematical models which attempt to
describe the movement of single or combinations of contaminants through soil
strata. This work has been concentrated in three main areas, i.e.,
descriptions of general flow through porous media, predictions of contaminant
transport, and predictions of contaminant retention (sorptive or other
attenuative characteristics of soils).
Ogata (1961) and Elzy, _e_t _al/ (1974) have concentrated on the problems of
vertical and lateral tansmissivity of liquids in soils, while Perrier and
Gibson (1982) focused their efforts on percolation and evapotranspiration.
These models face uncertainties associated with descriptions of the geologic
features (soil types, thicknesses, porosities, permeabilities) of a site which
must be incorporated into a quantification of leachate flow. Using finite
elements methods, Finder (1973) and Segol (1977) have attempted to model the
potential for leachate contamination of groundwater supplies, as have Pickens
and Lennox (1976) and Straub (1980). Sumner (1978) and Pettyjohn, et al.
(1981) have focused on the migration of leachate as a plume traversing from
beneath the landfill, whereas, several authors have concentrated on dispersion
and diffusion processes (Rubin and James, 1973; Van Genuchten, et^ _al_. 1977).
Other researchers have focused on reactions occurring between the subsurface
soil and occluded water (Van Genuchten, et_ a^., 1974; Selim, 1976; Dragun and
Helling, 1981).
Some investigators have attempted to describe the fate of specific
pollutants such as nickel and cadmium (Fuller, Q _a_l., 1981); cadmium
(O'Donell, _e_t al., 1977); iron, manganese, and zinc (Farquhar, 1977); salts
(Brunotte, et^ al_., 1970); and pesticides (Davidson, et_ aJU , I980b).
Intuitively it would seem that a large number of factors would influence the
attenuation of these pollutants, e.g., adsorption, liquid throughput,
microbial activity and pH, precipitation, and complexation. Moreover,
combinations of these factors would make effective modeling very difficult.
Nevertheless, these authors also report successful attempts at verifying their
models under controlled and defined conditions. While the models developed
may serve to evaluate the relative importance of specific parameters or
factors regulating leachate transport under these conditions, it is unlikely
at this stage that these models can be successfully extended to field
applications. Therefore, models need to be developed and verified under field
conditions, providing as much quantitative site data on test conditions,
geometry of components utilized and detailed results as possible.
Although the state of knowledge concerning the interaction of soils and
leachate has been enhanced over the last decade, particularly with respect to
attenuation, mobility and alteration of both leachates and the soils they
contact, relatively little is known about the actual changes that occur to the
soils themselves. Researchers have recently attempted to quantify the effects
on soil permeability, but very little is known about specific changes in soil
structure or fabric and the long-term stability of these alterations. Future
work should be directed toward quantifying the actual test conditions and the
changes in the physical properties of the soil as an aid to understanding the
role of the numerous parameters that effect interaction. Additionally, these
data would be extremely useful to those developing analytical models to
simulate such interactive processes.
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146
-------
APPENDIX A
BIOLOGICAL TREATMENT DATA
147
-------
TABLE A-1. Bench-Scale Experimental Data for the Activated Sludge Process Relating
ec to BOOS, COD, and TOC Removal
Reference
15,20,195
268-290
118.119
272
53.54,97
176,260,270
35,143
159
35.H3
35.143
151
205-207
26
228
28
244
22Z
0_
days
1
5
5
5
6
9
20
15
25
1.5
3^8
7.1
2
i
10
10
10
20
30
30
45
60
5.2
3.3
3 0
5 0
30
2.3
10.7
5.0
10
3.0
1 6
0 9
0.6
4. 1
1.8
1.0
0 6
0.4
0.22
3.9
2.2
1.5
1 2
0.67
0.35
45
20
9.9
3.3
.1.7
0.88
2.0
1 9
1.9
1.8
1.9
0 083
0 25
0.42
0.63
0.083
0.21
0.58
0.21
0.10
0 13
0.23
0.33
2.5
5
10
10
30
6
]2
20
30
6
10
15
20
30
10
10
10
10
10
12.5
12.5
4.7
13
1.2
2.5
5.0
10 1
15.0
20.0
BOD- > m
Influent
8000
1550
2900
7010
13,600
13.600
13.600
13,600
13.600
220
220
220
7100
7100
7100
7100
36,000
36.000
36,000
36,000
36.000
36 .000
2700
2700
2900
-
1-300
TJOO
-
1-300
VJOO
1-300
1-300
1-300
1-300
VJOO
1-3CO
1-300
1-300
VJOO
1-300
1-300
1-300
1-300
1-300
5250
5250
5250
i-lOOO
i-lOOO
MOOO
1480
i«80
i580
•^580
.
.
.
260
260
260
260
8300
6400
7600
6400
7900
7350
7350
7350
7350
7350
2220
2220
2220
ZZZO
5170
1 1 .250
750
6500
Z845
2845
Z845
2845
2845
2845
9/1
Effluent
7800
160
200
1400
26
20
6
20
12
37
ZO
Z5
7100
3400
26
12
130
3Z
27
90
66
75
10
20
Z5
-
-
-
-
,
_
_
_
_
_
_
-
.
.
.
.
.
.
.
75
42
36
30
2000
260
76
770
240
30
30
Z5
25
3820
_
_
_
25
25
20
60
837
261
52
16
9
12
COO.
Influent
9200
2700
6200
8800
19.300
19.300
19,300
19,300
19,300
.
15.800
15,800
15,800
15,800
48.000
48,000
48,000
48,000
48,000
48,000
3500
3500
3500
3800
3800
3800
530
530
1990
530
530
530
530
420
420
420
420
420
420
400
400
400
450
450
450
9400
9400
9400
1Z60
1260
1260
730
730
730
730
730
4500
4500
4500
4500
2420
2600
2600
1550
500
500
500
500
.
.
9950
9950
9950
9950
9950
9760
9760
9760
9760
7760
7760
10,400
3800
1500
8140
16,700
4000
11,500
4B05
4805
4805
4805
4805
4805
«sn
Effluent
6700
830
430
2300
580
470
300
420
360
15,800
8450
360
310
1550
590
460
610
430
390
90
100
110
170
1500
2200
340
345
1340
340
340
350
350
Z60
260
270
280
330
350
230
250
260
270
280
320
150
240
1ZOO
220
230
600
430
340
300
260
230
445
565
510
270
I860
650
700
850
290
250
205
Z10
_
.
240
240
200
200
6470
1150
860
610
470
1250
1160
1130
710
375
560
Z500
1600
3500
1554
697
300
220
160
155
roc.
Influent
.
-
6170
6170
6170
6170
6170
230
230
230
4600
4600
4600
4600
15,400
15,400
15,400
15.400
15,400
15,400
.
.
-
135
135
602
135
135
135
135
130
130
130
130
130
130
105
105
105
140
140
140
1700
1700
1700
310
310
310
200
200
ZOO
ZOO
200
1750
1750
1750
1750
620
720
770
-
320
320
320
320
.
3550
3550
3550
3550
3550
3200
3200
3200
3200
-
3200
16ZO
1620
1620
1620
1620
1620
•9/1
Effluent
-
_
-
.
-
151
136
130
.
1810
140
76
.
.
_
_
_
.
100
100
436
85
100
110
110
74
79
78
90
90
100
67
68
73
100
100
105
40
77
220
71
78
190
140
110
94
89
68
400
650
670
300
500
440
330
240
200
140
ISO
-
-
.
.
.
.
.
.
-
-
,
-
531
270
115
90
56
54
B00g
2.5
89.7
93.1
ao.o
99.8
99 9
>99.9
99 a
99 9
9CL9
88.6
0
52.1
99.6
99.9
99.6
99.9
99 9
«9 7
99 8
99.8
99.6
99.3
99.1
-
-
-
.
_
.
.
-
.
.
.
.
.
,
-
.
.
.
.
71. Z
83.8
86.2
88.5
76
96
99
88
97
99.6
99.6
99.7
99.7
48
-
.
99 5
99 8
97 3
99 1
70.6
90 1
98.2
99.4
99.7
99.8
Removal.
COO
Z7 2
69.2
93 1
73.8
97.0
97 6
98.4
97.8
98.1
-
0
46.5
97.6
98.0
96.8
98.8
99.0
98.7
99 1
99.2
97.4
97.1
96.9
60.5
42.1
35.8
34.9
32.0
35.8
35.8
34.0
34.0
38.1
38.1
35 7
33.3
21 4
16.7
42.5
37 5
35.0
40 0
37.8
28.9
98.4
97.4
87 2
82.5
81.7
5Z.4
41.1
53.4
58.9
64.4
68.5
90.1
87 4
88.7
94 0
23
75.0
73.0
45
«
50
59
58
.
-
97.6
97.6
98.0
98 0
35
88.2
91.2
93.7
95.2
83.9
85.0
89. 1
81.7
74.8
93.1
85.0
60 0
69 6
67.6
85.5
93.8
95.4
96.7
96.8
1 BOD5
101 CUB
0.87
0.57
0.47
0.80
0.70
0.70
0.70
0.70
0.70
40.1
43.5
0.45
60.7 0.45
92.6 0.45
98.4 0.45
0.75
0.75
0 75
0.75
0.75
0.75
0.77
0.77
0.83
•-0.80
10.80
26 10.66
26 10.66
n
37 10.66
25 10.66
19 i0.66
19 10.66
43 i0.66
39 i0.66
40 10.66
31 xO.66
31 10.66
23 i0.66
36 10.66
36 10.66
30 -0.66
Z9 i0.66
Z9 1-0.66
Z5 i0.66
97.6 0 56
95.5 0.56
87 1 0.56
77.1 iO 80
74 8 10. 80
39 10.80
30 10.80
45 10.80
53 10. SO
56 10.80
66 "J>.80
77 1
62.9
61.7
82.9
19
39
57
-
25 0.52
38 0.52
56 0.52
53 0.5Z
0.5
0.5
0.5
0.5!
0.5S
0.74
0.74
0.74
0.74
0.74
0.23
0 23
0 23
0.23
.
-
.
-
0 64
0.67
0.19
0.57
67.2 0.59
83.3 0.59
92.9 0.59
94.4 0.59
96.5 0.59
96.7 0.59
COD
TOT
,
3.1
3.1
3.1
3.1
3.1
.
-
3.4
3 4
3.4
3.4
3.1
3.1
3.1
3.1
3.1
3.1
-
_
3 9
3.9
3 1
3.9
3.9
3.9
3.9
3.2
3.2
3.Z
3.Z
3.2
3.2
3.8
3.8
3.8
3.2
3.Z
3.Z
5 5
5.5
5.5
4 1
4.1
4.1
3.7
3.7
3.7
3.7
3.7
Z 6
Z.6
2.6
Z.6
3.9
3.6
3.4
-
1.6
1 6
1.6
1 6
_
-
-
2.8
Z.8
Z.8
Z.8
Z.8
3.1
3.1
3.1
3.1
-
3 3
_
-
.
-
3.0
3.0
3.0
3.0
3.0
3.0
Coiments
T * 23-«°C
T • 23-25°C
T • 23-Z5°C
T • 23-25'C
A; r • 23-Z5'C
A; T " 23-25'C
A; T • 23-25°C
A; T • 24'C
A; T • 24'C
T • 18°C
T • 18°C
T • 22°C
1 • 22-C
T • 22'C
A; T • 22'C
A; T • 21 -25'C
A; T • 21-25'C
A; T • 21-Z5°C
A; T • 21-25°C
A; T • 21-25'C
A, I • 21-25'C
T - 25°C
T • 25'C
T « 25°C
T « 25°C
I • 25'C
T • 15'C
T « I5'C
T • 15°C
T • 15'C
T • 15'C
T * 15'C
I • 13°C
T - U'C
I » 13'C
T • 13°C
T • 13"C
T • 13'C
T * I6'C
I " 16'C
T • 16'C
T • 16'C
T • 16'C
T " 16'C
T - U'C
T • IZ'C
T « IZ'C
T • 12'C
T • 12'C
T • 12°C
T • 5«C
T • 10'C
T • 12°C
T " 18'C
T - 25'C
A; T • 23°C
A; f • 23'C
A; T • 23'C
A; T • 23'C
A; T • Z3'C
A; T • Z3°C
A; r • Z3'C
A; r • 23'C
I - 23'C
t " Z3'C
T • 23'C
T " 23'C
T • 23'C
T - 23°C
T - Z3'C
T • 23°C
T - Z3'C
A; T - 18-22'C
A; T • 18-2Z'C
A; I • I8-Z2°C
A; T - 18-22°C
T • I8-2Z'C
t • 22-23°C
T - 22-23°C
T " 22-Z3°C
T - 22-23'C
T - 2Z-Z3°C. Daw
1 • 22-23°C, Raw
P add.
T - 22-Z3°C, Lim
T • 22-2'3'C; 1 1
T • 2Z-23°C; 1 5
T • 18-ZZ'C
T - 18-ZZ'C
T • 18-22'C
T • 18-22'C
T - 10'C. COO:P
T » 10'C, COD-P
T " 10'C, COD-P
T - 10'C. COO-P
T =• 10'C, COO P
T - 10'C, COO:P
with
e
dilution
dilution
888888
- Data not given
A; Nutrient adjusted; B005-H:P-IOO:5-1
(Author called these AL
148
-------
TMLE A-Z. IwKti-Scclt txfMrtMftUl 0*U for Uw Acttvatrt $lu4gt Proem flilttlng
•00S «nd COO LMdtnq to 100, «M COO RMOV*! .
i
A
>*«,
MiroMl ""
11.20, IH 8.0
0.11
0.58
1.40
288-290 2.27
I.S1
0.68
111.119 0.91
0.54
272 0.14
0.04
0.01
51.54,97 !••
0.71
0.71
176,269.270 1.6
1 8
1 2
1 2
0 8
0.6
35 143 0 M
4 0.82
0.97
IS9
15,141
"'
"'
~
'.
j
"
15.141
151
205-207 2. 7
2.1
1.11
0.78
2* 3.3
1.3
0.76
0.64
0 26
228 0.11-
0.61
0.25-
0.37
28
-
^
244 0.41
0.92
0.16
0.50
230
260.261 o.97
0.97
0.97
0.97
0.97
0.97
291 2.3
2.3
22 2.4
1.1
0.6
0.3
0.2
O.IS
; Nutrient adjusted, 80
luolM,
. or CQO/r
9.2
0.55
1.04
1.7S
3.21
2.14
0 96
1.29
0.77
7.9
1 2
1 6
1.6
4.8
2.4
1.6
1.6
1.1
0.8
0 70
1 07
1 16
0.76
1.23
I.6J
0.06
0.11
0.20
0.18
0.32
0.59
0.92
0 10
0 23
0 41
0 70
1 02
1.89
O'l8
'0 26
0.37
0.67
1 29
a. 11
0.46
0.9S
0.18
0.73
1.44
0.17
0 38
0.38
0 40
0 39
54.0
18.0
11 0
7.2
29 0
13.0
4.5
7 4
S.2
4.0
2.2
1.5
|
0 41-
0.82
0 31-
0.50
0.98
O.SS
0.49
0.33
0.78
0.78
1.04
0.19
0-13
0.65
1.34
0.8S
0.88
0.79
0.80
0.75
0.86
0.76
;
3.2
3.2
4.0
1.9
0.95
0.48
0.12
0.24
05 K-P.IOO
u, m
InfluM
8000
IS50
2900
7010
13.600
11.6110
11,600
11.600
11.600
220
220
220
7100
7100
7100
7100
16.000
36.000
36.000
K.OOO
16.000
3S.OIW
2700
2700
2900
100
1.JOU
-
MOO
MOO
MOO
MOO
MOO
MOO
MOO
MOO
MOO
MOO
MOO
MOO
MOO
V300
MOO
MOO
S2SO
S250
5250
1-1000
vlOOO
•-1000
1480
•>S80
lAft)
•409
\
260
260
260
2fiO
8300
6400
7600
6400
7900
7350
7350
2220
2220
2220
2220
-
5170
11.250
750
6900
j
19,300
19,100
U.1CO
19.300
19.300
19,300
13.600
13.600
2H5
2845
2845
2845
2845
2845
5.1
}• *•/!
7800
160
200
1400
26
20
6
20
12
37
20
25
7100
1400
26
12
130
32
27
"0
66
7S
10
20
25
.
.
.
-
-
•
-
;
-
i
75
42
36
30
2000
260
76
770
240
10
25
25
25
20
60
j
80
55
16
300
1430
560
ICO
100
837
261
52
16
9
12
Cl
9200
2700
6200
8800
19.300
19.300
19,100
19.300
19,100
15,800
15.800
15.800
is.aoo
46.000
48,000
48,000
48.000
48.000
48,000
3500
3500
3500
3800
1800
3800
530
Sib
1990
530
30
30
30
20
20
420
420
420
420
400
400
400
4SO
450
450
HOC
MOO
9400
1260
1260
1260
730
730
730
730
710
4500
4500
4500
4500
2420
IMC
2600
ISSO
500
500
500
500
;
9950
9950
9760
9760
9760
9760
7760
7760
10,400
3800
1500
8140
16,700
4000
11,500
3940
4020
3750
4280
3820
30MO
30400
30>400
30400
30400
30400
19100
19100
4805
480S
4806
4805
4805
4805
» / n
», tn
6700
830
410
2100
580
470
300
420
360
-
is, an
8450
30
310
1550
590
460
610
430
390
90
100
110
170
1500
2:00
•10
345
1340
340
140
350
350
260
260
270
280
330
350
230
250
260
270
280
320
ISO
240
1200
220
230
600
410
340
300
260
230
44S
565
510
270
1860
K
840
290
250
205
210
-
240
200
1150
S60
610
470
1250
1160
1130
710
375
560
2500
1600
3500
920
770
510
850
850
_
900
900
1554
697
300
220
160
I5S
2.S
89.7
91 1
80.0
99.8
99.9
99.8
81.1
90.9
88.6
a ' 0
52.
99
99
99
99
99.
«9 7
99 B
99 B
99 6
99.3
99.1
„
.
-
.
j
'-
,
.
;
71.2
83.8
86.2
88.5
76
96
99
88
97
99.6
99.7
-
99.5
99 8
97 3
99 I
J
99.6
99.7
99.'4
92 6
97.1
99.3
99.3
70 6
90.8
M.2
99.4
99.7
99.8
I RMOV
COD
27.2
19.2
93.1
73. B
97 0
97 6
98.4
97.8
0
46.5
97.6
98.0
96. B
98.8
99 0
96.7
99 1
99.2
97 4
97.1
96.9
95.5
60.5
42.1
35.8
34.9
32.0
35.8
35.8
34.0
M.O
18.1
IB. 1
35.7
33.3
21.4
16.7
42.5
37.5
35.0
40.0
37.8
28.9
98.4
97.4
87.2
82.5
81.7
52 4
41.1
S3. 4
58.9
64 4
68 S
90.1
87 4
88.7
94.0
23
75. 0
73.0
45
42
SO
59
58
\
97.6
98.0
B8.2
91.2
93.7
95.2
83. 9
69.1
81.7
74. B
93.1
85.0
60.0
69 <
76
81
W
78
80
;
9S.3
95-3
67.6
8S. 5
91.8
95.4
96.7
96.8
" in,i !& 38
roc cor Toe
0.67 -
0,57 -
0.47
0.80
0.70 1.1
0.70 3.1
0 70 1.1
0.70 1.1
34.1
40.1 -
43.5
0.45 1.4
60.7 0.45 1.4
92.6 0.4S 3.4
98.4 0.4S 3.4
0.75 J.I
0.75 3.1
0.7S 3.1
0 75 1.1
0 75 3.1
0.75 3.1
0.77
0.77
0.83 -
10.80
. -0.80 -
10.80
26 10.66 3.9
26 10.66 1.9
3.3
37 10.66 3.9
26 i0.66 3.9
19 10.66 1.9
19 10.66 3.9
43 10.66 3.2
39 10.66 3.2
40 10.66 3.2
31 10.66 3.2
31 10.66 3.2
23 10.66 3.2
36 10 66 3.8
36 10.66 3.8
30 10.66 3,8
29 i0 66 3.2
29 10.66 3.2
25 10.66 3.2
97.6 a it 5.5
95.5 0.56 5.5
«7 1 0.56 5.5
77.1 10.80 4 I
74.8 10.80 4 1
39 i0. BO 4 1
30 10.80 3 7
45 i0. BO 3.7
53 10.80 3.7
56 10. BO 3.7
66 i0 BO 3.7
77.1 ,. - 2.6
62.9 - 2.6
61.7 - 2.6
82.9 - 2.6
19 - 3.9
39 - 1.6
57 - 3.4
25 0.52 1.6
38 0.52 1.6
56 0.52 1.6
S3 O.S2 1 6
0 5
0.5
0 5
0 51
O.Si
0.74 2.8
0.74 2.8
0.23 3.1
0.23 3 1
0.23 3.1
0.23 3.1
-
1.3
.
0.64
'0.67
0 19
0.57
:
0.63
0.63
0.61
0.63
0.63
0.63
0.70 3.1
0.70 3.1
0.99 3.0
0.59 3.0
O.S» 3.0
O.S9 1.0
0.59 3.0
0.99 1.0
Cmutiti
t • 23-iS'C
T • 23-29'C
I • 21-25'C
I • 23-25'C
A; I • 23-ZS*C
A; T • 23-Z5'C
A; T • 23-ZS'C
A; T • 24'C
T • U'C
T • 18'C
T • IS'C
T • 22'C
I • 22'C
T • 22'C
A. I • 22 C
A; T • 21-ZS'C
A. I • 21-25'C
A, T • 21-25'C
A; r • 21-25'C
A; T • 21-25'C
A; I • 21-25'C
I • 2S'C
t • 2S'C
7 • 25'C
I • 29'C
I • 25'C
t • 25'C
t • 19-C
I • IS'C
T • IS'C
T • IS'C
t • 15'C
T • IS'C
t • IS'C
T • ll'C
t • I3'C
1 • ll'C
t • ll'C
t • ll'C
T • IS'C
T • I6'C
T • I6'C
T • I6'C
I • U'C
I • I6'C
7 • 12'C
I • 12'C
r • I2'c
I • 12'C
I • 12'C
I • I2'C
r • s'c
T • 10*C
T • I2'C
I • I8'C
T • 25'C
A. T • 23'C
A; T • 23'C
A; T • 21'C
A; t • 23'C
A; I • 23'C
Ai 7 - 21'C
A; 1 • 23'C
A; I • 23'C
T • 23'C
T • 23'C
I • 23'C
I • 23'C
t • 23'1
I • 23'C
T • 23'C
I • 23'C
t • 23'C
A, t • 18-22'C
A, T • 18-22'C
I • 22-23'C
T • 22-23'C
I • 22-23'C
^ • 22-23'C
T • 22-23'C, R«
P Idd.
1 • 22-23'C, Itae
treated mthP idd.
1 * 22-23'C; 1 1 dilution
t • 22-23'C, 1:5 dilution
T • 18-22'C
T • 18-22'C
T • 18-22'C
7 • 18-22'C
T • 23'C; control
T • 23'C; ll-t .
F • 23'C, m,Co, Add
T • 23'C, life Add.
T - 23'C. »;* Add
T • 23"C 100:5:1.1
T • 23'C 100:4:1.1
r.- 23'C 100-3.2.1.
T • 23"C 100:4-0.32
T - 23'C 100:4:0.12
T • 23'C 100:1.2.0.12
T • 9'C
I • 9'C, A
T • 10'C, COO:P-IOO:
T - 10'C; C00:P-100:
r • lo'c! coo-p-ioo-
t • 10'C; COO:P-IOO:
T • 10'C; COO:P-100:
-------
*>-3. Bench-Scale Experimenla Data for the Activated Trocesi Relating Food to Microorganism (F/H)
Ratio to BOD. and COD Removal.
Reference
289,290
118,119
272
53.54,97
193,195
269.270
159
35,143
35,143
151
228
28
244
222
A • Nutrient
l,B005
SCu
0.18
0.35
0 49
0.18
0.29
0 16
0.35
0.72
0.16
0.43
0.14
„
._
..
0 074
0 067
0 11
0 089
0.12
0.22
,.
--
--
--
--
--
--
—
--
—
—
--
--
--
—
--
--
--
--
--
"
-
--
--
--
--
—
—
"
-
--
—
--
0 4-0.6
0.10-
0.18
._
--
--
--
0 064-
0 11
0.02
0.07
2 26
1.03
0 39
0.20
0.15
0 11
adjusted;
or COD
0.25
0 49
0 69
0.26
0.41
,.
-_
—
O.J6
0.97
0.31
0.012
0.016
0.025
0.038
0 050
0 099
0 090
0.15
0.12
0.16
0 30
0 11
0.2S
0.37
0.40
0.28
0.49
0.70
0.033
0.062
0 094
0.14
0 31
0.28
0 068
0 12
0 17
0 26
0.34
1 05
0 049
0 10
0 12
0.17
0.29
0.43
0.08
0.16
0 28
D 14
0.25
0 48
0.16
0 19
0 16
0 16
0.17
3.2
5.7
6 5
2 3
3 1
9.8
2 9
1 4
0 5-0.8
0.14-0 24
0.35
0 41
0 49
0 60
0 53
0.50
0.64
0.47
0.44
0.10-
0.16
0.11
0 12
3 81
1 75
0 66
0 34
0.25
0.19
BOD; « P-100-S
•BODS,
Influent
13,600
13,600
13.600
13.600
13,600
220
220
220
7,100
7.100
7.100
230
230
230
230
230
36.000
36,000
36,000
36.000
36,000
36.000
Z700
2700
2900
—
-_
-300
-300
-300
•300
•300
•300
•300
-300
-300
-300
•300
-300
-300
-300
-300
-300
-300
-300
5250
5250
5250
-1000
•1000
-1000
•580
-580
•580
•580
580
--
—
--
--
7350
7350
2220
2220
2220
2220
—
--
--
"
"
5170
750
6500
2845
2345
2845
2845
2845
2845
1
«,/.
Effluent
(
20
26
21
25
20
37
26
3400
10
..
75
66
91
27
32
130
10
20
25
-_
--
—
—
-_
__
__
--
.-
--
—
—
-.
—
..
..
..
--
--
—
--
--
„
--
--
30
25
--
—
-.
--
--
25
20
60
837
261
52
16
9
12
COO,
Influent
19.300
19,300
19,300
19,300
19,300
..
--
15.800
15.800
15,800
350
370
370
360
350
48,000
48.000
48,000
48.000
48,000
48. ODD
1 .990
3500
3500
3500
3800
3800
3800
530
530
530
530
530
530
420
420
420
420
420
420
400
400
400
450
450
450
9400
9400
9400
1260
1260
1260
730
730
730
730
730
4500
4500
4500
4500
2600
2600
2420
1S50
9950
9950
9760
9760
9760
9760
7760
7760
10400
3830
1500
8140
4000
11500
4805
4805
4805
4805
4805
4805
ntfl
Effluent
300
470
580
360
420
._
--
360
8450
310
36
38
44
45
50
390
430
610
460
590
1550
1342
90
100
110
170
1500
2200
340
345
340
340
350
350
260
260
270
280
330
350
230
250
260
270
280
320
150
240
1200
220
230
600
430
340
300
260
230
270
510
565
445
700
650
1860
850
240
200
470
610
860
1150
1250
1160
1130
710
375
560
1600
3500
1554
697
300
220
160
155
Demova
BOTr —
-99 9
99 9
99 8
99.9
99.8
88.6
90 9
83.1
99.6
52.1
99.9
--
--
99 8
99.8
99.7
99 9
99.9
99 6
-
99.6
99.3
99.1
„
..
..
._
„
._
..
„
-_
._
._
..
..
..
._
-_
,_
•-
__
._
..
„
-.
99.6
99.7
__
--
--
—
..
--
--
-
99.5
97 3
99 1
70.6
90 8
98.2
99.4
99.7
99 8
CQD
98.4
97.6
97.0
98 1
97 8
--
--
97 6
46.5
98.0
89.8
89.7
88 1
87.5
85.7
99.2
99 1
98.7
99.0
98.8
96.8
32.0
97.4
97.1
96.9
95.5
60.5
42 1
35.8
34.9
35 8
35.8
34 0
34 0
38.1
33.1
35 7
33 3
21.4
16.7
42.5
37 5
35.0
40 0
37 8
28 9
98 4
97 4
87 2
82 5
81,7
52.4
41. 1
53.4
58.9
64.4
68.5
94 0
38 7
87 4
90 1
73 0
75.0
23 1
45 2
97 6
98.0
95 2
93 7
91.2
88.2
S3 9
as o
89 1
81 7
74 8
93.1
60 0
69 6
67 6
85 5
93.8
95.4
96.7
96 8
BOD,
LUU
0 70
0.70
0.70
0.70
0.70
._
"
0 45
0.45
0.45
0.66
0.62
0 62
0.64
0.66
0.75
0 75
0.75
0.75
0.75
0.75
0 77
0.77
0.83
0 80
0.80
0.80
0.66
0.66
0 66
0.66
0.66
0.66
0.66
0.66
0 66
0.66
0.66
0 66
0.66
0 66
0 66
0.66
0.66
0 66
0 56
0 it
0.56
0 80
0.80
0.80
0.80
0.80
o ao
0.60
0.80
_,
0 74
0.74
0 23
0.23
0.23
0 23
0 23
0.23
0.23
0.23
-
0 64
0 19
0 57
0 59
0 59
0.59
0.59
0.59
0 59
TO?
3.1
3.1
3.1
3.1
3.1
__
—
"
3.4
3.4
3.4
..
3.1
3 1
3.1
3,1
3.1
3.1
3.3
._
_.
3.9
3.9
3.9
3.9
3.9
3 9
3.2
3.2
3 2
3.2
3.2
3.2
3 8
3.8
3.8
3.2
3.2
3 2
5 5
5.5
5.5
4 1
4 1
4.1
3 7
3 7
3 7
3.7
3.7
2 6
2.6
2.6
2.6
3.4
3 6
3 9
2.8
2.8
3.1
3 1
3 1
3.1
3.1
3.1
3 3
3.3
3.0
3.0
3.0
3.0
3.0
3.0
lomnents
T • 24'C. A
T • 24-C; A
T • 24°C; A
T " 24°C; A
I « 24°C, A
T • 1S°C
T • 18°C
T • 18T
T • 22°C
T • 22'C
T • 22"C; A
T " 23°C, 1-25 dllut on
T - 23°C, 1 25 dllut OR
T • 23°C, 1:25 dilut on
7 « 23'C, 1 25 dilut on
7 • 23'C, 1:25 dilut on
T - 23"C, A
7 • 23"C, A
T • 23-C. A
I • 23'C. »
7 • 23"C; A
^ • 23'C. A
7 . 15'C
7 = 25°C
7 • 25"C
7 » 25'C
7 « 25"C
7 « 25"C
7 • 25"C
7 « 15"C
7 » I5"C
7 » I5"C
7 - I5"C
7 * 15"C
7 * 15"C
7 * 13"C
7 « 3"C
7 • 13°C
7 » 13"C
7 • 13"C
7 • 13"C
7 - 16"C
7 • 16"C
7 • I6"C
7 - 16"C
7 ' 16"C
7 • 16'C
7 • 12°C
7 • I2°C
7 • 12'C'
7 - f2°C
7 - 12"C
7 - 12°C
7 ' 5"C
7 - 10"C
7 " 12"C
7 - 18°C
7 • 25-C
A; 7 23°C
A, 7 23°C
A; 7 23"C
A, 7 23°C
A, 7 23°C
A, 7 23"C
A; T 23"C
A; 7 23"C
A, 7 18-22°C
A, 7 I8-22°C
7 • 22-23-C
7 • 22-23-C
7 • 22-23"C
7 • 22-23-C
7 • 22-23-C, raw
7 • 22-23°C, raw + P add.
7 • 22-23"C 1 i»e
treated w/P add
7 • 22-23"C 1 1 dilut on
7 • 22-23"C. 1 5 dilution
7 - 18-22 'C
7 " 18-22-C
7 • 18-22-C
7 • 10°C; COD P-100:
7 • 10°C, COD:P=100-
7 • ID'C; COD-P'IOO:
7 • 10-Ci COD:P'IOO-
7 - 10"C; COD:P'100:
7 • 10°C; COO-P-100-
• Data not given
150
-------
TABLE A-4 Bench-Scale Experimental Data for the Activated Sludge Process For Heavy Metal Removal.
45
118.119
260,261
269,270
288-290
168
5j.54.97
151
222
PH
9
9
9
9
9
9
8
8.3
8 6
8 9
8.5
8.7
8.7
8.8
8.7
8.5
8.8
8.7
8.6
8.3
8.3
8.3
8.3
8.3
8.3
8 4
8 4
8 4
a
8.4
7 6
7.6
7
a 6
C3 —
--
0.072
0 072
0.072
0 072
0.072
0.072
0 39
0.39
0.39
0.39
0 39
0.39
0.04
0 04
0.04
0.04
0.04
0.04
0 00(5
0.0015
0 0015
<0.005
tnflu
-
0.10
0.37
0 37
0 37
0.37
0.37
0.37
.9
9
.9
9
.9
.9
0 44
0 44
0.44
0.44
0.44
0.44
0 017
0.017
0.017
0.14
snt Concentration, rug
2130
2130
2130
1020
1020
1020
1130 0.028
990 0. 7
990 0. 7
990 0. 7
990 0. 7
990 0. 7
990 0. 7
960 . 4
960 . 4
960 . 4
960 44
960 44
960 .44
1230
1230 --
1230 --
1230 —
1230 -
1230 --
0 030 W 2 0 045
0.030 20.2 0.045
0.030 20 2 0.045
240
240
0.08 102 0.11
V-
0.11
._
_-
.-
__
--
0.65
0.65
0.65
0 65
0.65
0 65
0.18
0.18
0 18
0 18
0.18
0.18
0 002
0 18
~K
72
72
72
55
55
55
31
50
50
SO
50
50
50
220
220
220
220
220
220
39
39
39
39
39
39
1.17
17.6
-
97
99
99
39
97
99
97
98
99
97
98
99
95
95
98
85
85
95
•67
.67
-67
R
--
-
--
75
86
91
90
n
89
91
93
97
97
97
98
97
98
99
98
97
94
98
47 1 --
58.8 --
64.7 -
78 >90
•moval.
99
99
99
99
99
96
97
99
,99
97
99
99
99
>99
99
99
99
99
-99
99
>99
99
98
99
96
94
97
*96
*96
98
%
'-'-
--
82
94
96
98
86
97
91
80
84
85
84
88
90
..
—
—
"
94
94
94
73
N1 Zn Comments
>99 Varied e • 7-86 days
>99
>99
>99
>99
75 96
97 Varied nutrient addition.
99
>99
98
99
99
99 Varied e = 10-60 days
99 c
>99
>99
>99
>99
67 99 * T = 9-25"C
61 '99
(1 99
56 98
44 -99
»c • 3 days
5 days
7 days
• dried 8^ a uaays.
39 95 »c • 10 days, T • 10°C
TABLE A-5. Bench-Scale Experimental Data for the Activated Sludge Process for Alkali and Alkaline
Earth Metal Removal.
Reference
45
53,54.97
118,119
151
206-208
260,261
168
269,270
288-290
222
DH
9
9
9
9
9
9
8.4
8 4
7 6
7 6
a
7
8.2
8 2
8 2
8.2
8 3
a 6
8.9
8.5
a. 7
a 7
8 4
8.4
8 4
8.8
8 7
8.5
8 8
8 7
8.6
8.3
8.3
8.3
8.3
8.3
8.3
8.6
Influ
Ca
3780
3780
3780
3010
3010
3010
1200
1200
1200
1200
-
as
100
100
100
100
—
.-
•550
550
550
1400
1400
1400
1400
1400
1400
775
775
775
775
775
775
348
ent Concentration, mq/1
Hfl
660
660
660
310
310
310
170
170
170
170
69
100
35
35
35
35
__
.-
._
39 2
39 2
39 2
310
310
310
310
310
310
72
72
72
72
72
72
37
nn
,.
--
—
..
-
13
3.0
—
35
35
35
35
35
35
4 1
4 1
4 I
41
41
41
41
41
41
14
14
14
14
14
14
23
K
1240
1240
1240
500
500
500
--
--
--
-
900
200
200
200
200
._
--
—
44
44
44
1060
1060
1060
1060
1060
1060
..
.-
__
153
Na
1350
1350
1350
310
810
810
"
-_
--
-
-
430
430
430
430
„
--
—
--
-.
—
120
120
120
..
,.
--
—
._
._
._
180
Ca
99
99
99
99
99
99
97
98
65
64
-
97
66
71
75
75
--
69
69
69
99
98
98
95
96
94
94
94
90
95
95
93
88
Removal, I
1*1
79
82
81
74
79
76
18
29
26
18
36
90
11
3
14
9
..
--
--
—
5
5
5
62
71
73
73
64
68
48
45
58
50
48
60
11
Mn
..
--
—
-
-
--
>96
90
—
-.
98
97
99
90
97
97
99
97
97
96
98
99
99
>99
,99
99
99
99
99
99
99
93
K
22
23
32
11
a
17
--
"
..
16
30
20
30
20
-,
.,
0
0
0
35
33
38
36
42
46
..
„
_,
22
Ha Comments
35 Varied e « 7-86 days Considered AL
n c
32
20
19
24
Varied n - 5-10 days Control
c Ltme Addition
Lime Addition
Control
0 Varied s • 2.3-8 hours.
0 c
0
0
Varted nutrient addition
,.
0 >3 days
0 g 5 days
0 7 days
Varied o • 10-60 days
c
—
Varied H - 6-20 days *• I - 9-25"C.
c
nc - 10 days, T - 10"C
-- Data not given.
151
-------
TABLE A-6. Bench-Scale Data for Nitrogen Conversion and Removal for the Aerobfc Processes.
Loading
r COW
n3-dav influent N, FIB/1
V
Reference days
35,143
193,195
143
159
53.54,97
269,270
244
222
- Oata
* AS -
AL =
4 1
1 8
1.0
0 6
0 4
0.22
3.9
! 2
1 5
1 2
0 67
0.35
3 3
1 7
0.88
2 0
1.9
1 9
1.8
1.9
6.9
T-37
T-IO
45
20
9 9
10
10
10
10
10
5
10
20
30
30
45
60
12.5
10
10
10
10
10
10
20
20
20
20
20
20
not given
Activated
B005
^
,
,
f
.
_
0.033
.
0.71
0.71
0.71
0 71
1 42
3 6
i.a
1.2
1.2
0 8
0.6
0.65
0.28
0 28
0.28
0.28
0.28
0.28
O.I
0.1
0.1
0.1
0.1
0.1
sludge
COO TKN
0.10 110
0.23 110
0.41 110
0 70 110
1 02 110
1.89 110
0.10 115
0.18 115
0 26 115
0.37 134
0.67 134
1 29 134
0.38 169
0.73 176
1.44 232
0.37 236
0.38 239
0 38 228
0 40 262
0 39 268
0 052 12
OOK 113
0.041 105
0 21 250
0 46 250
0 95 250
0 20
1 58 280
1 58 280
1 58 780
1 58 780
3 16 280
4 8 1390
24 1390
1 6 1390
1.6 1770
1 07 1770
0.8 1770
-1 0
0.48 157
0 48 234
0 48 338
0.48 484
0.48 685
0.48 1051
0.24 161
0 24 266
0 24 385
0.24 541
0.24 778
0 24 1184
NH3-N
.
.
134
134
134
228
-
.
.
329
10
10
510
510
10
:
970
80
157
261
407
608
974
81
186
305
461
698
1104
NOj-N
3.2
3 2
3 2
3.2
3.2
3.2
0.7
0.7
0.7
0.1
O.I
0.1
O.I
0 1
O.I
0.3
0.3
0 3
0 3
0 3
3 2
3 2
0 1
0.1
0.1
9 7
19
19
19
19
19
-
.
Effluent N.
TKN
34
35
29
33
56
93
34
34
33
36
32
118
45
47
232
228
170
55
18
3
5
35
65
14
29
102
16
13
21
23
118
29
24
13
70
39
23
163
237
297
479
698
986
6 6
8 i
a 4
8.4
8.4
8 2
6 4
8 4
8 4
7 6
7 6
8 0
a 8
a. 7
8 5
8 8
8.7
8.6
8.6
8.6
8 6
8.6
a 6
a. 6
a 6
8.6
8.2
6.0
6 0
8 3
Comments*
T • 13°C. AS
T • 13°C, AS
T • 13'C, AS
T " 13°C, AS
T • 13°C, AS
T • 13'C, AS
T • 16°C, AS
T • 16°C; AS
T • 16°C, AS
T » 16°C, AS
T • 16'C; AS
T • 16'C, AS
T • I2"C. AS
T • I2'C; AS
T . 12'C; AS
T • 5'C. AS
T • 10°C, AS
T • 12°C; AS
T . 18°C, AS
T • 25'C, AS
T - 23'C; 1 25 dilution; AS
T • 12'C, AL
T . 12'C: AL
T . 12"C; AS
T . 12°C; AS
T • 12'C; AS
T = I5"C; AS
AS; T • 22'C
AS; T • 22°C
AS, T • 22'C
AS. I • 22'C
AS; T • 22'C
AS; T • 23°C
AS; T • 23'C
AS; T • 23'C
AS; T • 23°C
AS. T • 23'C
AS; T • 23°C
T • 18-22'C. AS w/
(anaerobic) tank
AS; T • 10'C
AS, ; = 10"C
AS; T • 10'C
AS; T • 10°C
AS; T " 10°C
AS; T • 10°C
AS. T • IO°C
AS; T - 10'C
AS, T - 10°C
AS. T • IO"C
AS. T . 10'C
AS, T * 10°C
Aerated lagoon
152
-------
TABLE A-7. Experimental Data for the Combined Treatment of Leachate with Domestic
Wastewater for Bench-Scale and Pilot-Scale Studies Using the Activated
Process.
Reference
19,20
44.45,70,73
286
42,43
59
176,260,261
228
- Data not
Leachate , %
Domestic MM
1
2
5
10
20
, 0.5
1
2
3
4
2
2
2
0.5
0.5
1.0
2.0
1
3
6
10
20
2
3
a
given
B005, m
Influent
225
310
570
1000
18?0
270
390
670
900
1100
670
S10
570
150
_
_
235
590
1130
1850
3640
210
370
ZOO
Combined Ouality
9/1
COO, mg/1
Effluent Influent
.
_
.
~
3
3
3
3
5
3
3
6
4
-
_
5
14
11
8
16
8
9
13
350
450
770
1300
2360
465
710
1200
1690
2160
1200
-
-
250
770
870
1070
_
_
-
-
-
335
550
380
Effluent
24
31
38
59
113
35
35
40
45
60
40
-
-
30
135
85
200
_
-
-
-
-
38
40
39
Remova 1 , %
WB^ COT)
_
-
.
-
9C.9
99.2
99.6
99.7
99.5
99.6
99.5
98.9
97.3
-
.
97.9
97.6
99.0
99.6
99.6
96.3
97.5
93.6
93.1
93.1
95.1
95.5
95.2
92.5
95.1
96.7
97.3
97.2
96.7
-
-
88.0
82.5
90.2
81.3
-
-
-
-
-
89. 3
92.0
89.8
kg BOOg or
COD/m3'dav
BOOj
0.23
0.31
0.57
1.00
1.87
.
-
-
-
-
-
-
-
.
-
_
0.012
0.03
0.06
0.09
0.18
0.20
0.42
0.36
COD
0.35
0.45
0.77
1.30
2.36
.
-
-
-
-
-
0.51
0.58
0.71
.
-
-
-
0.25
0.57
0.46
gBOD- or COD
F/M- M-vls-day '
BOOS
_
-
_
-
0.3
0.3
0.3
0.3
0.3
0.3
0.6
1.0
-
-
_
-
-
-
-
-
0.10
0.22
0.14
COO
_
.
.
-
0.55
0.55
0.55
0.55
0.55
0.55
1.1
1.8
0.51
0.50
0.49
-
-
-
-
-
0.12
0.30
0.18
Comnents*
BS ; BOD, ^8970 ;COD -10,800
BS;80D,'8970;COD^=10,800
BS ; 800^8970 ;COC^»1 0 ,800
BS,800L«8970;COD^-10,800
BS ;800J--8970 ;COO[-. 10 ,800
BS;BOO, =24,700;COOL»49,300
BO;BOD,-24,700;CODL=49,300
BS,BOOL=24,700;COOL-49,300
B5;800L-24,700;COOL-49,300
BS,BOOL-24,700;CODL=49,300
BS;BOOL-24,700;COO(.-49,300
BS ; 600^=Z4 , 700 ;COOL=49 , 300
BS ; BODJ--24 , 700 ;CODL=49 ,300
BS
BS
BS
BS
BODj.N:P
BS;800. -19,300 1 00:4:1
BS;BOD, -19,300 100:5:0.5
8S; BOO, =19,300 100:4 0.26
BS; SOD, -19,300 100-3.6:0.3
BS;BOOj| = 19,300 100:3.6-0.1
PS; I = 10-I5°C
PS; r - 10-15-C
PS, T • 10-15°C
*8S - Bench-Scale
to raw leachate concentration in mg/1. All tested at T = 23°C unless specified otherwise.
TABLE A-3. Bench-Scale Experimental Data for the Aerated Lagoon Process.
Organic Loading,
kg/m3.day F/M' RT
Reference T.days
26 10
30
40-46 7
15
30
30
60
86
35,143 10
37
244 70
70
70
70
10
too
82
55
41
100
82
55
41
168 2
3
5
7
7
10
BOD5
0.64
0.26
_
-
-
-
.
-
0 01
0.01
0.02
0.10-0.40
0 50
0.60
0 70
0.80
0.90
1.0
0.09
0.12
0.18
0.24
0.09
0.12
0.18
0.24
0 47
0 35
0.21
0.15
0 13
0.09
COD BODj
.
-
5.0
2.3
1.2
1.9
0.97
0.67
0.042 -
0.011
_
-
-
-
-
-
-
-
-
0.17
0.21
0.31
0.42
0.17
0.21
0.31
0.42
G.79
0.59
0 35
0.25
0 22
0.16
LVSS-day
COO
.
-
0 37
0.20
0.12
0 19
0.11
0.084
.
-
.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
0 93
0.61
0.37
0.31
0.33
0.26
B005,
Inf.
6400
7900
,
-
-
-
-
-
.
-
,
-
-
-
-
-
-
9840
9840
9840
9840
9840
9840
9840
9840
940
1040
1040
1040
940
940
mg/1
770
240
.
-
-
-
-
_
-
10
10
15
10
10
10
20
60
100
200
5
5
5
5
70
50
40
55
28
9
10
7
8
8
COD, mg/1
_
-
35 ,000
35 ,000
35 000
58,000
58,000
58,000
420
420
_
-
-
-
-
-
-
-
17.100
17,100
17,100
17,100
17,100
17,100
17,100
17,100
,580
,760
,760
,760
,580
1,580
.
- '
1030
820
540
670
540
415
310
290
_
_
-
-
-
_
-
-
-
350
400
350
400
1200
1400
1200
1200
275
215
200
175
170
170
TOC, mg/1
Inf.
.
-
11.800
11,800
11.800
19,400
19,400
19,400
132
132
_
-
-
-
-
-
-
-
-
-
.
-
-
-
-
-
-
_
Eff .
.
380
310
210
240
180
160
94
91
,
_
.
-
-
_
-
-
-
-
.
_
-
-
-
-
-
-
-
-
BOOc
88
97
_
-
-
-
-
-
.
-
99
99
99
99
99
99
99
99
98
96
99.8
99.9
99 9
99.9
99.3
99.5
99.6
99.4
97 0
99 1
99 0
99.3
99 1
99 1
% Removal
COD
.
-
97 1
97.7
98.5
98.8
99.1
99.3
26
31
_
_
-
-
-
-
98.0
97.7
98.0
97.7
93.0
91.8
93.0
93.0
82.6
87,8
88.6
90.1
89.2
89 2
TOC
-
96.8
97.4
98.2
98.8
99.1
99.2
29
31
_
-
-
-
-
_
-
-
-
-
-
-
-
.
_
80D5 COD
Oiff TOT
0.5
0.5
3.0
3.0
3.0
3.0
3.0
3.0
0.66 3.2
0.66 3.2
0.
0. -0.4 -
0. -0.4 -
0.
0.
0.
0.
0.
0.
0.
0.56
0.56
0.56
0.56
0.56
0.56
0.56
0.56
0.6
0.6
0.6
0.6
0 6
06
Comments
T=23°C
T»23°C
A*;T"23°C
A*;T=23°C
A*;T=23°C
A*;T=23°C
A*;T-23°C
A*,T.23"C
T-12°C
T-12°C
T=20°C
T=20°C
T-20°C
T>20°C
T»20°C
T=20°C
T-20°C
T-20°C
T-20-C
T=20°C
T=20°C
T-20-C
T-20°C
I.20"C
T=5°C
T=5°C
T-5°C
T=5°C
I=2I-24'C
T=21-i4°C
T=21-24°C
T-21-24°C
T=21-24°C
T=21-24"C
Data not given
' Nutrient Adjusted COO'N:P=164-8-l
153
-------
TABLE A-9. Bench-Scale Experimental Data for the Anaerobic
Process Relating ec to 8005, COD. and TOC Removal.
Reference Process
19.20.195 PFR-SG
33,217 CSTR-SG
98,220 CSTR-SG
98.220 PFR-AG
143 PFR-AG
143 PFR-AG
151 CSTR-SG
205-207 CSTR-SG
14 PFR-SG
44-47 CSTR-AG
135.136 CSTR-SG
223 PFR-AG
30 CSTR-SG
237 PFR-AG
V
days
5
5
10
10
10
12.5
12.5
20
20
5
10
20
10
20
20
20
20
10
1.5
2.25
4 5
26
26
73
5 7
3.3
12
12
15
18
28
0.10
0 17
0.33
1
5
10
10
10
15
0.1
0 16
0.33
1
5
10
15
6.4
6.6
7.5
17.5
74
10
15
20
1.8
30
30
30
0.25
0.50
1 0
2.0
3 0
2.0
3.0
BOO,,
Influent
9100
1820
18,200
3640
8400
8400
9100
18,200
7300
13,000
13,000
13,000
_
.
-
.
-
2700
2700
2700
24,500
24,500
24.500
5950
5950
5950
5950
5950
5950
5950
3880
4200
4800
3600
3400
1300
1900
1940
1530
3700
3700
3700
3700
3700
3700
3700
-
3940
3940
3940
2600
1000
4000
10.000
950
950
950
950
950
950
950
"9/1
655
165
1680
220
150
95
195
790
225
2150
935
435
1500
2100
2050
24.000
21 .800
180
110
50
65
40
30
55
3500
3620
4600
2300
700
170
80
135
100
3400
3400
4100
2600
470
80
75
320
250
Z05
100
250
2000
.
.
COO. «9/l
11.200
2240
22,400
4430
10,600
10.600
11,200
22,400
8960
Z6.000
26,000
26,000
12.900
12.900
12.900
12.900
12,900
12,900
3600
3600
3600
38.800
38,800
38,800
9100
9100
9100
9100
9100
9100
9100
6200
6300
6690
6120
5300
2740
2900
2480
2470
6000
6000
6000
6000
6000
6000
6000
25,000
32.000
32.000
32.000
32.000
7350
7350
7350
3200
1870
1870
1870
1870
1370
1870
1870
970
225
1780
380
700
560
450
1540
630
8250
7300
4900
1060
600
630
2860
340
500
1900
3100
3000
38.800
35.900
600
520
270
720
775
420
420
600
6200
6250
5850
4760
2100
720
400
375
200
6000
6000
5400
4020
1090
670
140
2000
3000
2000
1400
1000
700
650
420
1160
950
190
170
180
160
450
220
TOC, «g/l
.
_
,
-
_
-
9100
9100
9100
4600
4600
4600
4600
4600
4600
:
2260
2260
2280
2230
830
1100
880
810
.
„
-
1260
1260
1260
-
.
-
,
_
_
,
_
"
_
_
.
,
.
.
-
280
260
180
730
230
200
.
_
.
_
.
;
2100
2050
2025
1760
190
160
190
220
.
.
_
-
.
-
_
-
-
_
Removal, I
80D5
92.3
90 9
90.8
93.9
98.2
98.9
97.9
95 7
96.9
83.3
92. 8
96.6
_
44 4
24.1
2.0
II 0
99.3
98.2
99 2
98 9
99 3
99 5
99 2
10
14
4
22.2
79 4
86.9
95.8
93.0
93.5
a
8
0
30
87 3
97 3
97 3
.
-
.
91 3
93 6
94.3
85
95
30
.
.
COO
91.3
90.0
92.1
91.5
93 4
94.7
96.0
93.1
93.0
68.3
71.9
81.2
91.8
95.3
95.0
77.4
93.4
96.1
47 2
16.9
0
7.5
98.5
94.3
97 0
92 1
91,5
95 4
95.4
93.4
0
13
22 2
73 7
86.2
84.9
91 9
0
0
10
33
81 8
33.3
97.7
92
75
93 8
95.6
96.9
90.5
91 1
94 3
63 8
50
88
90
90
91
76
88
TOC
.
_
.
.
,
.
.
_
-
93.9
94.3
96.1
84 1
BOO;
5oTT
0 81
0 81
0 81
0.81
0.79
0.79
0.81
0.81
0 31
0.5
0.5
0 5
-0.45
-0.45
-0.45
-0.45
95.0 -0.45
95.7
-
_
_
_
.
-
7
9
11
-
77J
85 S
78.4
72 3
.
.
_
.
-
_
-
.
.
-0.45
0.75
0.75
0.63
0.63
0.63
0 65
0.65
0.65
0.65
0.65
0.65
0.65
0 63
0.67
0.72
0 59
CL47
0.66
0 78
0.62
0 62
0.62
0 62
0 62
0.62
0.62
0 62
.
.
0 54
0 54
0 54
0.81
.
.
0.51
0.51
0.51
0.51
0.51
0 51
0.51
•
_
.
.
.
-
2.9
2.9
2.9
2.8
2.8
2.8
2.8
2.8
2.8
-
.
.
-"
2.7
2.8
2.9
-2.6
3.3
2.6
2.8
3.0
.
.
.
>3.0
>3 0
3 5
3.5
3 5
5 8
5.8
5.3
-
2.6
2.6
2.6
i.6
2.6
2.6
2.6
(
T
T
T
T
T
T
T
T
T
A
A
A
A
A
A
T
T
T
T
T
T
T
T
T
T
T
T
T
A,
A
A
A
A
A
A
A
A;
A;
A;
A-
A-
A;
A
T
T
T
T
T
T
T
T
T
T
T
T
T
T
r
T
T
T
T
ornwnts
• 23-30'C
• 23-30'C
" 23-30'C
« 23-30°C
- 23-30'C
* 23-30'C
• 23-30'C
- 23-30'C
• 23-30'C
T " 34'C
T « 34"C
T • 34'C
T • 35'C
T • 35'C
T " 35°C
T • ZO'C
T . 35'C
• 35'C
• 25'C
* ll'C
. ire
• 23'C; 1 11 ecycle
- 23°c, 1.11 ecycle
• 23'C, 1:11 ecycle
• 23'C, I'll ecycle
= 23'C; 1 11 ecycle
• 23°C, 1 11 ecycle
• 23'C. 1-5 recycle
• 23°C, 1-5 recycle
• 23'C; 1-5 recycle
• Z3'C; 1-5 recycle
T ' 37'C Batch
T • 37'C Batch
T - 37°C Batch
T • 37'C Bat h
T • 37'C 3at h
T - 37'C Con Inuous
T • 37'C Con Inuous
T • 37'C Con Inuous
T • 37'C
T • 37'C
T • 37'C
T • 37'C
1 • 37'C
T • 37'C
T • 37'C
• 33'C
• ZO'C
• 23'C; 1 4 4 recycle
• 23'C. 1 8.7 recycle
- 23'C, 1-35 recycle
• 35'C
• 35'C
• 35'C
• 24'C
• 24"C
" 24'C
• Z4'C
" 25"C
• 25'C
• 25"C
• 25'C
• 25'C
• 10"C
• 10"C
""Data not given
A • Nutrient Adjusted, BODS N:P - 100:5-1
154
-------
TABLE A-10. Bench-Scale Experimental Data for the Anaerobic Process
Relating BODS and COO Loading to B005 and COO Removal.
Loading,
kgBODg or COD/
m3-day
Reference
19,20,195
38,217
98,220
98.220
143
143
151
205-207
14
44-47
135-136
223
30
237
Process
PFR-SG
CSTR-SG
CSTR-SG
PFR-AG
PFR-AG
PFR-AG
CSTR-SG
CSTR-SG
PFR-SR
CSTR-AG
CSTR-SG
PFR-AG
CSTR-SG
PFR-AG
BOO,
0.36
0.36
0.37
0 67
0.84
0.73
0.91
1.82
1.32
0.65
1 30
2.60
.
_
-
-
I.S
0 6
1.2
0.34
0.94
0.94
0.21
0 40
0.50
0.72
0.50
0.33
1.04
0.10
0.19
0. 19
0.13
0.68
3.6
14
25
37
0.25
0.37
0 74
3.7
11.2
23
37
-
_
0.20
0.26
0 39
1.4
0.03
0 13
0.33
3.8
1.9
1.0
0 S
0 3
0.5
0.3
COD
0 «S '
0.45
0.45
0.35
1 06
0.90
1.12
2.24
2.24
1 30
2.60
5 20
0.65
0.65
1 29
0.65
0.65
1.29
2 4
0.8
1 6
0.53
1 5
1 5
0 33
0.61
0.76
1.1
0.76
0.51
1.6
0.17
0.25
0.29
0.27
1.06
6.1
20
39
60
0.40
0.60
1.2
6
18
38
60
4 0
4 9
0 89
2 6
5.3
0.37
0 49
0.74
i.a
.
.
7 6
3 a
2 0
1 0
0.64
1 0
0.64
B005, HO./1
Influent
1820
3640
7300
3400
8400
9100
18,200
9100
18.200
13.000
13.000
13.000
.
.
.
2700
2700
2700
24.500
24.500
24,500
5950
5950
5950
5950
5950
5950
5950
1530
1940
1900
1300
3400
3600
4800
4200
3880
3700
3700
3700
3700
3700
3700
3700
3940
3940
3940
2600
1000
4000
10000
950
950
950
950
950
950
950
Effluent
165
220
225
95
ISO
195
790
655
1680
435
935
2150
.
,
1500
2050
2100
ISO
24,000
21.800
55
40
65
50
30
110
100
135
60
170
700
2800
4600
3620
3500
75
80
470
2600
4100
3400
3400
205
250
320
-
100
250
2000
-
COO. II
Influent
2240
4480
3960
10.600
10.600
11.200
22.400
11,200
22,400
26.000
26,000
26,000
12,900
12.900
12.900
12,900
12.900
12.900
3600
3600
3600
38.800
38,800
38.300
9100
9100
9100
9100
9100
9100
9100
2470
2480
2900
27«0
5300
6120
6690
6300
6200
6000
6000
6000
6000
6000
6000
6000
25,000
32.000
32.000
32.000
32.000
7350
7350
7350
3200
1870
0/1
Effluent
225
380
630
560
700
450
1540
970
1730
4900
7300
8250
630
600
1060
2860
840
500
1900
3000
3100
600
38.800
35.900
600
420
780
270
720
420
520
200
375
400
720
2100
4760
5850
6250
6200
140
670
1090
4020
5400
6000
6000
2000
8000
1000
1400
2000
420
650
700
1160
-
950
190
170
130
160
450
220
Remov
BOD;
90.9
93 9
96.9
98.9
98.2
97.9
95.7
92.3
90 8
96.6
92.8
83.3
.
.
-
44 4
24.1
22.2
99 3
2.0
11.0
99.2
99 3
98.9
99.2
99 5
98.2
93.5
93.0
95.8
86.9
79.4
22.2
4
14
10
97 8
97 8
87.3
30
0
3
3
.
-
94 8
93 6
91 8
85
95
80
.
-
1. 1
COO
90.0
91.5
93 0
94
93
96.
93.
91.
92.
81.2
71 9
68.3
95.1
"5.3
91 8
77.4
93.5
96.1
47 2
16 7
13 9
98.5
0
7 5
93.4
95 4
91 5
97.0
92 1
95.4
94 3
91.9
34 9
73 7
60 4
22. 2
13
<1
0
97.7
88 a
81.8
33
10
0
0
92
75
96 9
95 6
93 8
94 3
91 1
90 5
63.8
.
-
50
38
90
90
91
76
38
BOOt
5oTT
0.81
0.81
0.81
0.79
0.79
0.81
0.81
0.81
0.81
0.5
O.S
0.5
-0 45
-0.45
-0.45
-0 45
-0.45
-0.45
0 75
0.75
0 75
0 63
0 63
0 63
0 65
0.65
0.65
0.65
0.65
0.65
0.65
0 62
0.78
0.47
0.64
0.59
0.72
0.67
0.63
0.62
0.62
0.62
0.62
0 62
0 62
0 62
0.54
0 54
0.54
0.81
-
-
COD
TO
.
.
2.9
2.9
2.9
2.8
2.3
2.8
2.8
2.3
2 3
•
-
-
-
.
-
-
3 0
2 3
3.3
2 4
-2.6
2 9
2.8
2.7
-
>3.0
>3.0
3.5
3 5
3 5
5.8
5 8
5.8
.
Comments
T
T
T
T
T
T
T
T
T
A
A-
A
T
T
T
T
T
T
T
T
T
T
r
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
I
T
T
F
T
23-30'C
23-30'C
23-30'C
23-30'C
23-30'C
23-30'C
23-30'C
23-30'C
23-30'C
T • 34'C
T • 34'C
T • 34'C
• 35'C
• 35°C, A
• 35'C. A
• 20'C; A
• 35'C. Hrne treated
• 35°C; lime treated
• 25'C
• ll'C
. ll'C
• 23'C
• 23'C
• 23'C; 1-11 recycle
• 23'C; 1:11 recyc e
• 23'C; 1 11 recycle
• 23'C; 1:5 recycl
• 23'C; 1:5 recycl
• 23'C; 1:5 recycl
• 23'C; 1:5 recycl
• 23'C; 1 5 recycl
• 37'C. A, Ba ch
- 37"C; A; fla ch
• 37"C, A; Ba ch
• 37'C; A; Ba ch
• 37°C; A; Si Ch
- 37'C; A; Continuous
- 37'C; A; Continuous
• 37'C; A; Continuous
• 37'C; A
• 37'C. A
• 37'C; A
• 37'C; A
• 37°C; A
• 37'C; A
• 37'C. A
• 33°C
• 20°C
• 23°C; 1:35 recyc e
• 23'C. 1:8.7 recycle
• 23'C. 1-4 4 recycle
• 35'C
• 35°C
- 35'C
' <4°c, lime treated
• :rc
• 24"C
• Z4"C
• 25'C
• 25-C
• 25'C
« 25'C
• IO"C
• IO°C
• 10'C
- Data not given
A - Nutrient Adjusted; B005 N-P • 100 S.I
155
-------
TABLE A-11. Bench-Scale Experimental Data for the Anaerobic
Process for Methane and Gas Production.
Influent,
Reference Process
19,20,195 PFR-SG
33,217 CSTR-SG
98.220 PFR-AG
CSTR-SG
44-47 CSTR-AG
143 PFR-AG
151 CSTR-SG
14 PFR-SG
135,136 CSTR-SG
2J3 PFR-AG
30 CSTR-SG
237 PFR-AG
- Data not given
A • Nutrient Adjusted.
B005
8400
8400
18.200
9100
18.200
9100
7300
3640
1820
13,000
13,000
13,000
.
.
2700
2700
2700
24,500
24,500
24,500
5950
5950
5950
5950
5950
5950
5950
1530
1940
1900
1300
3400
3600
4800
4200
3880
3940
3940
3940
2600
1000
4000
10000
950
950
950
950
950
950
950
10D5.N-P
COO
10,600
10.600
22.400
1 1 .200
22.400
11,200
8960
4480
2240
26,000
26.000
26.000
12.900
12.900
12.900
12.900
12.900
12,900
19,500
39,000
3600
3600
3600
38.800
38 .800
38.800
9100
9100
9100
9100
9100
9100
9100
2470
2480
2900
2740
5300
6120
6690
6300
6200
25,000
32,000
7350
7350
7350
3600
1870
1870
1870
1870
1870
1870
1870
100-5:1
Loading,
ko 80D5 or COD/
•3-dar
BOO,
0.84
0.67
1 82
1 82
0.91
0.73
0.37
0.3E
0.36
0.65
1.30
2.60
-
,
.
-
_
-
1.3
0 6
1 2
0.34
0 94
0.94
0.21
0.40
0.50
0.72
0 50
0.33
1 04
0.10
0 19
0 19
0.13
0.68
3 6
14
25
37
0 20
0.26
0 39
1.4
0.03
0.13
0 33
3 8
1 9
1.0
0.5
0.3
0.5
0 3
COD
1 06
0.85
2 24
2.24
1 12
0 90
0.45
0.45
0 45
1.30
2.60
5.20
1.29
0.65
0.65
1.29
0 65
0.65
0 33
0 98
2.4
o.a
1.6
0.53
1 5
1.5
0.33
0 61
0.76
1 1
0.76
0.51
1 6
0.17
0.25
0 29
0.27
1 06
6.1
20
39
60
4 0
4 9
0 37
0.49
0.74
i.a
6 8
2.7
1 4
0.7
0.5
0.7
0.6
V
days
10
12.5
10
5
20
12.5
20
10
5
20
10
5
10
20
20
10
20
20
42
74
1.5
4 5
2.25
73
26
26
28
IS
12
8.3
12
IB
5.7
15
10
10
10
5
1
0 33
0.17
0.10
6.6
6.4
20
IS
10
1 8
30
30
30
0.25
0.5
1
2
3
2
3
CH,P
T/K9
BOO;
destr
BOO,
.
_
.
.
-
_
600
600
690
-
.
-
,
-
.
_
_
,
,
.
.
_
_
-
805
_
540
490
510
37
45
-
.
reduction. Gas Production,
l/k9
or COD BODj or COD
oyed destroyed
COD
.
.
-
.
.
.
.
-
360
390
420
1020
335
390
310
295
320
975
475
.
-
.
.
-
520
390
300
350
21
60
.
-
440
440
440
305
355
315
340
285
305
3iO
BODS
545
487
334
412
398
418
346
398
213
840
910
880
_
.
-
265
0
0
690
0
0
500
440
370
390
.
520
250
1080
640
635
580
620
290
44
56
0
750
820
S80
-
.
_
COD
454
403
308
340
332
346
294
332
175
500
570
540
14SO
450
525
430
415
420
1250
610
190
0
0
440
0
0
350
300
260
260
295
355
170
700
490
460
360
425
170
25
75
0
520
420
3SO
450
380
887
330
330
330
350
445
385
425
375
370
380
Gas
Composition, t
CH4
.
-
-
69.2
72.3
75 4
70.0
74.3
74.3
74.3
71 3
75.7
78
78
.
-
-
74.6
95
84
82
83
80
-
-70
-70
-70
75
75
75
79
77
82
83
8c
34
32
co2
.
-
.
-
-
24.3
23 4
23.4
22.0
22.1
22.1
22.1
14.7
20 3
.
-
-
-
.
-
18.3
13
13
15 4
13
IS
25
25
25
10
9
12
y
7
6
8
"2
.
.
.
-
6.1
3.0
1.0
8.0
3.6
3.6
3.6
14.0
3.5
.
.
-
.
.
.
7 1
.
1 6
2.7
2 0
4
5
-
-
-
B005
CDTT
0.79
0.79
0.81
0.81
0 81
0,81
0.81
0.81
0 81
0.5
0.5
0 5
-0.45
-0.45
-0.45
-0 45
-0.45
-0.45
0.75
P 75
0 75
0.63
0.63
0.63
0.65
0.65
0.65
0.65
0.65
0 65
0.65
0.62
0.78
0.66
0 47
0.64
0.59
0.72
0.67
0.63
-
0 54
0.54
0 54
o.ai
-
-
0.51
0.51
0.51
0.51
0.51
0 51
0.51
COD
TOT
.
-
-
-
-
-
-
2.9
2.9
2.9
2.9
2.8
2.8
2.3
2 8
2.8
3.5
3.5
.
_
-
-
-
-
.
-
.
-
3.0
2. a
2 6
3.3
2.4
-2 6
2.9
2.8
2.7
>3.0
-•J 0
5.8
5.8
5 8
2.6
i 6
2 6
2.6
2.6
2 6
£.6
Comments
T 23-30°C
T 23-30°C
T 23-30'C
T 23-30'C
T 23-30-C
T 23-30°C
T 23-30-C
T 23-30-C
T 23-30"C
A; T • 34°C
A; T • 34°C
A; T • 34°C
T • 35"C
A| T • 3S°C
Ai T • 35"C
A; T • 35°C
A; T • 20"C
L1«» treated; T * 35"c
T - 23°C:1:20 recycle
T • 23-C-.1.35 recycle
T • 2S-C; Batch
T * 11-C; Bate
T • 11-C; Sate
T • 23°C. Con nuous
T • 23"C. Con nuous
T - 23BC; Con nuous
T - 23°C; Con nuous
T - 23°C; Con nuous
T - 23°C; Con nuous
T • 23°C; Con nuous
T • 23°C; Con nuous
T * 23°C; Con nuous
T " 23"C; Cont nuous
T " J7°C; A Batch
T • 37°C; A Batch
T - 3J-C; A Batch
T * 37'Ci A Batch
T - 37-C, A Batch
T • 37°C; A Batcn
T » 37°C; A Continuous
T - 37°C; A; Continuous
T - 37°C. A; Continuous
T • 33-C
T - 20°C
T • 35'C
T - 35°C
T • 35°C
I • 24-C. lime treated
T 24"C
T 24"C
r 24°c
T 25°
T 25°
T 25
f 25"
T 25"
T 25'
T 25 C
156
-------
TABLf A- 12 Bencn-Scale Experimental Data for the Anaerobic Process
for Heavy Metal Removal
Influent Concentration, mq/1
Reference Process ph
14 PFR-SG 7.9
33.217 CSTR-SG
68,70,73 CSTR-AG 7.4
143 PFR-AG 7
7 5-8.0
7.5-8.0
7.5-8.0
7.5-8.0
7.5-8.0
7.5-8.0
7.5-8.0
151 CSTR-SG 7.1-7.5
147 PFR-AG 7.3-8.0
- Data not given
Cd
0 03
0.1
0.03
0.01
0.03
0.03
0.03
0.03
0.03
0.03
0.03
-
0.01
Cr Cu Fe
0.32 0.3
0.22 0.03 600
1.7 5.6 430
0.45 0.3 245
.0 .30 810
.0 .30 810
- .0 .30 810
.0 .30 810
.0 .30 810
.0 .30 810
.0 .30 810
- 336
- 0.05 36
TABLE A-13.
Pb HI Zn
0.12 0.43 26
- 1.2 16
0.76 0.19 65
0.38 1.2 16
- 0.70 5.0
1. .2 155
1. .2 155
1. .2 155
1. .2 155
1 .2 155
1.4 .2 155
1.4 1.2 155
6
0.05 - 0.19
Bench-Scale Experlm
Cd
0
>99
52
0
0
0
0
0
0
0
0
-
0
•ntal
Cr
40
45
91
0
90
90
90
90
90
90
90
-
-
Removal. %
Cu
77
40
88
50
50
38
69
69
-
72
46
-
0
Data for the
for Alkali and Alkaline Earth Metal R
Influent Concentration, pnl/1
Reference Process
33,217 CSTR-SG
151 CSTR-SG
PH
-
7.1-7.
Ca Mg
1330 120
5 315 70
Mn K Na
18 530 530
6.2 347 313
Ca
31
30
Fe
-
80
97
94
99
98
93
97
96
98
96
97
62
Pb
0
-
50
84
_
0
0
0
0
0
0
0
-
92
N1
60
10
86
84
71
67
67
83
67
75
75
75
-
-
Zn
98
95
95
94
80
>99
98
98
>99
99
>99
99
>90
0
Counts
T - 20°C
T = 33"C
T = 34°C
T = 23°C
T = 25°C
T • Z3°C
T = 23°C
T • 23°C
T = 23°C
T = 23°C
T = 23°C
T - 23°C
T = 37°C
T = 25°C
Anaerobic Process
*moval
Removal, t
Mg
10
7
Mn
69
92
K
6
0
Na
4
0
Coninents
T ' 34°C. Added Ume to raise pH.
T • 37°C
- Data not given
157
-------
APPENDIX B
PHYSICAL/CHEMICAL TREATMENT DATA
158
-------
TABLE B-l. Bench-Scale Experimental Data for Chemical Coagulant Addition
Reference
19,20
53,54.97
133
134
28
238
158
143
151
96
Coagulant*
Alum
FeCI3
Alum*Lime
FeCl3*FeS04*Lin»
Po)ymer*Lfme
Alum
Alum
Alum
Alum
Alum
Alum
Fed,
Fed,
Fed,
Fed;
FeClj
FeSO, *t ime
FeSOtHlme
FeSOjtLime
FeSOj*Lime
Alum
Alum
A urn
lum
lum
lum
lum
lum
ed.
ed3
ed3
ed3
ed.
ed3
ed3
Alum
Alum
A urn
A urn
A urn
Fed,
Fed,
Fed,
Fed3
Fed;
Fed,
Fed,
Feet;
Fed?,
Alum
Alum
lum
lum
lum
lum
ed,
ed.
ed
Fed,
Fed;
Fed;
A urn3
Alum
Alum
Alum
Fed,
Fed,
Fed;
Fed;
A urn3
Alum
A urn
Fed,
Fed3.
Fed,
Alum* Ime
A urn* Ime
Alum* fme
A urn* ime
A urn* Ime
Alum* lire
FeSO. Lime
FeSO:*L1me
FeSOj'Llme
Alum
A urn
Alum
Alum
Alum
A urn
Alum
Alum
Alum
Alum
Alum
Alum
Alum
Alum
Alum
A urn
Alum
Alum
Dose. mo/1
10-1000
100-1000
Alum-600
Lime* 1640
FeCl3-1000,
Lime*1640
FeSO, * 1450
Polymer*15
L1me*1000
riot given
10
50
100
500
1000
100
500
1000
1000
1000
760>600
760*1 700
1 360*0
1360*660
1000
2500
5000
6000
7000
3000
9000
10,000
1000
1500
2000
2500
100
ISO
200
90
135
180
90
135
180
Old not
Specify
450-
3150 mg/1
pH ,,.-5.4
opt
75
130
200
75
130
200
90
150
240
90
ISO
240
75
130
200
75
130
90
150
90
ISO
75
130
200
90
ISO
240
1000*530
1400*0
1400*660
1400*1850
1 750*930
2250*1060
0*165
270+400
550*530
30
45
55
65
75
90
30
45
55
65
75
90
30
45
55
65
75
90
pH
Initial
6 0
6.0
5.4
5.4
5.4
7 6
7.0
7.0
7.0
6.4
6.0
6.3
6.3
5.9
5.9
5.9
6.4
6 4
6.4
6.4
7.3
7.3
7 3
7.3
7.3
7.3
7.3
7.3
7.2
7 2
7.2
7 2
6.6
6 6
6.6
6.6
6.6
6.6
6.6
6.6
6.6
.
-
.
.
,
.
.
.
-
.
.
6 4
6 4
6 4
6 4
6.4
6.4
6.4
6.4
6.4
5.4
5 4
5.4
5 4
5.4
5.4
5.5
5.5
5.5
5.5
5.5
5.5
5 5
5 5
S 5
5.5
S.S
5.5
Final
7.
5-7
8 0
8.0
8.0
6 3
7.
7.
7
7
7.
6
6
6
5
7
7 0
3.5
6.3
7 0
7.3
7.0
7.1
7.0
7.1
7.1
7.0
7 1
7.1
7.0
7.1
6.9
7.3
7.3
7.3
6.3
6.2
6.
7.4
7 4
7.2
-
.
7 ;
; 7
7.7
6
6
6
7 5
7 5
7.5
9
9
9
7 6
7 4
6 6
b
6
7
7
9
9
6
6
6
9
9
9
7 I
5 5
7 0
8.5
7 1
7.1
7 0
7 0
7 2
3.2
3.2
3.2
3 2
8 2
8.2
8.2
8 2
8.2
8.2
8 2
8.2
8.2
8.2
8 2
8.2
8 2
8.2
COD, mq/1
Influent
9100
9100
17,000
17.000
17.000
100(BOD5)
9100
9100
9100
9100
9100
9100
9100
9100
9100
9100
-
10.650
10.650
10,650
10,650
10,650
10,650
10,650
10.650
10.700
10.700
10.700
10,700
1240
1240
1240
1240
1240
1240
1240
1240
1240
11 ,600
4380
1570
320
690
6480
1200
350
520
530
530
530
530
530
530
530
530
530
530
530
530
400
400
400
400
400
400
400
400
400
170
170
170
170
170
170
35 ,000
35 ,000
35.000
35,000
35,000
35.000
34.000
34.000
34,000
34.000
34 ,000
34 ,000
33,000
33.000
33,000
33.000
33.000
33,000
Effluent
9100
>7740
14,800
15,100
15.100
25
8700
8400
9100
8700
3600
8100
8400
8700
8400
7800
_
9780
10.230
10,160
9770
9990
10,200
10.100
10,200
9980
9940
9720
9560
1160
1400
1410
1100
1090
1300
1250
1080
1100
.
-
-
480
460
490
490
475
485
450
480
465
470
480
465
355
360
355
355
355
355
350
350
160
125
125
153
137
135
-
-
33.500
30.000
28.000
27.000
27,500
28.500
32,500
30,500
29,500
28.500
29,000
29 .000
32 .000
30.000
29 .000
28.000
29.000
29.000
TOC
influent
_
-
_
,
.
.
-
1750
1750
1750
1750
3120
3120
3120
3120
3120
3120
3120
3120
3100
3100
3100
3100
430
430
430
430
430
430
430
430
430
.
-
.
_
-
-
50
50
50
50
50
50
1750
750
750
750
750
750
750
750
750
-
-
.
.
.
.
mg/1
Effluent
.
-
-
.
.
_
_
,
_
-
1500
1490
1520
1570
2800
2750
2500
2320
2540
2570
2550
3550
2550
2570
2520
2480
410
400
410
380
390
390
410
410
410
.
.
-
-
.
43
38
35
45
43
45
1600
1590
1510
1500
1490
1050
1710
1550
1480
.
-
-
-
Removal .'
COO TM
0
<15
13.3
11.5
11.5
4.4
7 ^
0
4.4
5.5
11
7.7
4.4
7.7
14
.
.
8
4
5
8
6
4
5
5
7
;
9
11
6
0
0
1!
12
0
0
13
11
88
97
83
64
39
88
79
66
52
10
13
8
8
10.5
8.5
15
10
12 5
12
9.5
12.5
11.3
10
11.3
11.3
11.3
11 3
12.5
12.5
5.3
26
26
8.9
19
21
-
4
14
20
23
22
20
4
10
13
16
15
15
3
9
12
15
12
12
-
_
_
_
.
.
IS
15
13
10
10
12
20
26
19
18
18
18
18
19
19
20
5
7
5
12
9
9
5
5
5
_
,
.
-
-
-
-
_
-
.
-
-
14
24
30
10
14
10
8.9
9 0
14
14
15
40
2
12
15
_
-
-
iW-
SO 9
500 mg/1
20 9
500 mq/1
_
-
-
4
3
5
85
50
130
10
21
33
67
28
120
160
2
13
90
IV1
uo
130
130
125
100
120
190
220
250
275
50
30
-
-
_
-
.
.
-
•
-
_
-
-
-
-
85
80
100
100
130
190
20
40
100
-
-
-
-
Leachate
Type"
R
R
_
R
R
R
J:
p
£
£
£
-
R
R
R
R
fl
R
R
R
R
R
R
R
R
R
R
R
R
ft
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
B
B
B
B
B
B
B
B
B
B
B
B
B
8
B
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
• Data not given
• Alum as Al^SO,,)-,
Lime as Ca(OH)2
' R - Raw leacnate
B * Biologically treated effluent
159
-------
TABLE 5-;. Oench-Scale Experimental Data for Chemical Precipitant Addition
17,18,176
19,20
44,45,70
53,54.97
134
143
265
118.119.261
28
238
239
Precipitant Dote, ma/1
Line*
Lime
Ha2S
Line
Line
Lime
NaOH
Lime
Lime
Lime
Lime
Lime
Lime
Lime
Lime
Lime
Lime
Line
Na«S
Nais
Nah
Hais
cla2S
Line
Lime
Lime
Lime
Lime
Lime
Lime
Lime
Lime
Line
Line
Line
Lime
Lime
Lime
Lime
Lime
Lime
Lime
Lime
Lime
Line
Line
Lime
Line
Lime
Lime
Lime
Lime
Lime
Lime
Lime
Lime
Line
Lime
Line
Line
Lime
Lime
Lime
Lime
Lime
Lime
Lime
Lime
Lime
Lime
Lime
Lime
NaOH
NaOH
Lime
2350
750-1750
10-1000
1000-0000
* 1500-4000
2760
2660
S70
1000
1150
1280
1390
1600
1C40
1060
2700
470
1400
10
25
50
100
500
1000
pH 9
pH 10
pH 11
pH 12
pH 9
pH 10
pH 11
PH 12
pH 9
pH 10
pH 11
pfl 12
ISO
300
450
600
750
900
1050
1200
1350
1500
ISO
300
450
600
700
750
300
900
1000
1100
1200
100
500
900
1500
1000
2500
5000
6000
7000
8000
9000
10,000
190
190
225
22!
200
240
6.000
pH
5.3
6.0
6.0
7.4
9
5.4
5.4
6.0
6.0
6.0
6.0
6.0
6.0
6.0
7.8
7.8
9.0
9.0
6.0
6.0
6.0
6.0
6.0
6.0
.
.
-
-
-
6.3
6.3
6 3
6.3
6.3
6.3
6 3
6.3
6.3
6.3
5 3
5.3
5.3
5.3
5.3
5.3
5.3
5.3
5.3
5.3
5 3
3.0
8.0
8.0
8 0
7 1
7.1
7 1
7 1
7.1
7 1
7 1
7.1
6 6
6.6
6 6
6 6
6.6
6.6
5.8
6.9
8.5-12
6.0-6.3
12
12
11.0
11.0
9.0
9.5
10.0
10. S
11.0
11.5
12.0
9.0
11.0
10.0
11.5
6.0
6.0
6.0
6.1
6.3
6.4
9
10
11
12
9
10
II
12
9
10
11
12
6.6
7.2
7.9
8.3
9 4
9.7
10.3
10.9
11.2
11. S
6.2
6.5
6.3
7.0
6.9
7.1
7 0
7 2
7.2
7.3
7 4
3.2
10. S
11.5
11 8
7.6
8.1
8.4
9 7
10. 1
10.4
11.7
12.1
7 0
7.0
7.9
7.9
7.7
7.8
12.2
COD, mq/l TOC. mq/1 Removal.: 51ydpe.
14,000
10.6SO
10,650
.
700
17,000
17,000
10.700
10,700
10,700
10,700
10,700
10,700
10,700
560
560
370
370
10.700
10.700
10,700
10,700
10.700
10,700
530
530
S30
530
400
400
400
400
170
170
170
170
5030
5030
5030
5030
5030
5030
5030
5030
5030
5030
12.900
12.900
12.900
12.900
12,?00
12,900
12,900
12.900
12,900
12,900
12.900
400
400
400
400
10.660
10.660
10.660
10,660
10,660
10,660
10.660
10.660
1240
1240
1240
1240
1240
1240
22.900
9200 5200
10.650
10,650
700
560
14,900
15.400
10.600
10,400
9970
10.300
10,700
10,100
10,400
560
515
370
260
10,200
10,000
10.700
10.200
10.170
10,600
490
480
445
440
370
370
360
355
113 50
147 50
135 50
104 SO
4620
4350
4280
4330
4340
4240
4140
3930
3350
.
12.200
1 1 ,600
1 1 ,400
10.800
10.700
10.200
10.500
10,050
9730
9580
9500
385
360
300
2tO
10,450 3290
10.600 3290
IO.OCO 3290
9600 3290
9580 3290
9720 3290
9570 3290
9620 3290
1210 430
1190 430
1030 430
1010 430
1 160 430
1160 430
20,700 9850
2700 34
0
0
48
.
520 - 2698000
2094000m)/ !
13
9.3
1.0
2.3
6.8
3.7
0
5.6
2.8
0
8.0
0
30
4.7
6.5
0
4 7
4.9
1.0
7
10
16
17
7.5
7.5
10
11.3
53 3.0
40 13
45 20
35 38
8.2
14
15
13
13
16
18
22
24
.
5.4
10
12
16
17
21
19
22
24
26
26
4
10
25
35
3170 2
3170
-------
TABLE B-3. Bench-Scale Experimental Data for Heavy Metal Removal for the Chemical Addition Processes.
Reference
J7.18.I76
143
151
229
133
26
19,20
32
134
265
28
28
238
96
Chemical
Ca(OH),
"3
A] -(SO.),
AIM SO.),
FeU,
Fed?
Ca(Ori)-
Ca(OH)£
Al.(SQ.)_
Jill?*1'
Fecn
Ca(Oii).
Ca(OH)|
Ca(OH),
Feio, * 3
°3
At (SO.),
Ca(OH)2
Ca(OH)2
Cln
AljISO.),
FeCl 3 ' 3
Ca(OH)2
Cl(OH),
CafOHl?
Na,S
Na's
Al2(SO,)j
FeEl. 4 3
Fed,
FeCl,
Cl? 3
Ca(OCl),
KMnO, '
KMnO:
KHnO,
0, 4
°3
Ca(OH),
Ca(OH)i
Ca(OH)5
ta(Otl),
Ca(OH)|
Ca(OH).
Ca(OH);
Ca(ON)i
Ca(OH);
Ca(OH)j
Ca(OH);
Ca(OH|;
Ca(OH),
Fed,
Fed,
Fed,
FeClf,
AI2(SO,)3
Alf(SOJ)3,
Al (SO )
AI^ISO4,)3,
»'» sojl?
A)2JS04(3
Alj(SOj),
FeCl,
FeClX
Fed3
Alum3
Alum
Alum
Alum
Alum
Alum
Ca(OH),
Ca(OH),
Ca(OH)i
Ca(OHU
NaOH '
HaOH
NaOH
NaOH
Alum
Oose, mg/1
2350
130-250
75
75
90
90
pH 9
pll 11
75
75
90
90
ptl 9
pH 11
165
1400
1360
249T-4 hrs
1650
750
1000
400
500
1000
1000
2000
2500*200
870
1020
500
1000
100
500
500
1000
1000
800
1000
50
100
500
5000 » 1 hr
5000 » 4 nr
ISO
300
450
300
900
1000
2500
5000
6000
7000
8000
9000
10.000
1000
1500
2000
2500
1000
2500
5000
6000
1 7000
3000
9000
10.000
100
150
200
90
135
130
90
135
130
190
190
225
225
200
240
300
360
65
PH
6.9
6.9
7 7
6
7 5
9
9
11
7 5
6.0
7.0
9.0
9
11
7.0
6.3
8.8
6.8
10.5-11.0
8.5
3.5
5.8
7 1
7.0
8.0
8.8
9.0
9.5
6.3
6.4
6.9
6.4
6
6
7
7 0
7.0
5.8
5.8
5.8
7.8
7.5
6.6
7.2
7.9
6.5
7.2
7.6
8.1
8.4
9.7
10 1
10.4
11.7
12.1
7.1
7 0
7.1
6.9
7.3
7.0
7.1
7 0
7 1
7.1
7.0
7.1
7.3
7.3
7.3
6.3
6.2
6.1
7.4
7.4
7.2
7 0
7.0
7.9
7.9
7.7
7 8
7 8
s!o
3.0
0.2
Influent Concentration, mq/l
Cd Cr Cu
- 0.39
- 0.39
- -
- -
- -
- -
- -
- -
.
_
0 . 56
0.05 - -
-
: : :
.
.
.
.
-
.
_
.
.
.
_ _
_
_
_
.
.
.
- -
_
_
~
.
,
,
.
.
.
- -
.
.
,
-
- 0.064 0.07
- 0.064 0.07
- 0.064 0.07
- 0 064 0.07
- 0.064 0.07
T 0 064 0.07
0.064 0.07
- 0.064 0.07
0.064 0.07
0.064 0.07
0.064 0 07
- 0.064 0 07
- 0.064 0 07
- 0 064 0 07
0.064 0.07
0 08 0 035
- O!OB o!o35
- 0.08 0.035
- -
Fe Pb Mi
47
47
85
85
85
85
21
21
21
21
26
26
26
73
1000 -
330 -
330 -
85
330 -
330 -
21
21
330 -
330 -
330 -
330 -
85
35
35
85
85
3.7 -
38
330 -
330 -
330 -
45
45
115 -
115 -
115 -
790 -
790 -
220 -
220 -
220 -
220 -
220 -
220 -
220 -
220 -
150 -
150 -
150 -
ISO -
165 -
165 -
16S -
165 -
165 -
165 -
165
165 -
34
34
34
8
8
a
8
8
a - -
84
34
84
34
34
84
SO
80
500 -
Zn Cd
12.5 -
12.5 -
0.82 -
0.82 -
0.82 -
0.82 -
0.37 -
0.37 -
0.37 -
0.37 -
30
30
30
-
8 20
-
.
"
.
.
.
.
•
.
.
.
_
-
_
_
_
_
-
_
.
.
.
-
_
.
_
.
.
-
.
.
,
.
,
.
,
.
.
-
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.5
3.5
-
Cr
-
-
-
-
-
-
-
_
-
-
-
-
_
-
_
-
_
_
_
_
:
.
_
_
_
_
_
.
.
.
-
.
_
_
_
-
_
,
_
_
_
.
„
_
,
.
.
.
-
.
_
_
-
S3
53
53
53
S3
S3
53
53
53
S3
30
53
S3
S3
S3
63
63
Cu
96
96
-
-
•
-
-
_
89
-
.
:
-
.
.
-
.
,
.
_
-
_
_
_
.
-
.
.
,
.
.
.
.
,
.
,
.
•
.
.
31
36
21
7
0
0
43
21
21
14
7
36
64
64
64
57
43
Removal.
Fe Pb
99
99
99
99
99
99
99
99
97
97
93
98
33
99
0
54
0
93 20
99
>99
»99
95
99
97
98
52
93
99
>99
18
79
60
94
55
62
98
99
99
45
77
99
82
96
21
70
99
26
70
87
91
91
96
>99
>99
>99
^99
73
77
82
79
86
87
96
96
97
96
94
97" -
98
98
77
98
>99
>99
>99
>99
>99
1
12
97
98
91
99
95
94
97
98
X
Ht Zn
>99
>99
>90
>90
>90
>90
>90
>75
>75
32
>75
>75
>75
98
99
99
4
>99
_
.
- -
,
,
_
_
.
•
.
.
_
.
_
_
_
.
-
_
.
.
.
-
.
„
.
_
.
.
,
-
_
.
-
97
97
97
91
89
93
95
96
97
43
0
95
97
88
94
91
95
leachate
Type"
R
R
1!
R
R
R
S
g
B
8
R
R
R
R
R:F.jll Scale
0(1:1)
0(1:1)
R
0(1 1)
0(1:1)
R
R
0(1.1)
0(1-1)
0(1-1)
0(1:1)
R
R
R
8
R
0(1.25)
0(1:1)
0(1:1)
0(1-1)
0(1:1)
«
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
II
R
R
R
R
R
R
R
R
ft
R
R
R
R
R
R
R
R
«
R
R
R
R
R
R
R
R
R
R
• Data not given
' R = Raw leachate
B * Biologically treated leachate
0 * Diluted raw leachate
161
-------
TABLE 3-4. Bench-Scale Experimental Data for Alkali and Alkaline Earth Matal Removal for the
Chemical Addition Processes
Reference Cnenncal
17,18,
32
151
265
- Data
176 Ca(OH)2
°3
Ca(OH)2
Ca(OH)2
Ca(OH)2
A12(SO,J
FeS04
Ca(OH)2
Ca(OH)2
not given
Dose, mg/1
2350
180-250
2000
+ FeCl3 2500+200
165
3 1400
1360
300
900
Influent Concentration, mg/1 Removal ",
PH
6.9
6.9
8.0
3.8
7.0
-
6.3
6.5
7.2
La
-
-
-
-
178
178
178
-
Mg
-
-
-
-
100
100
100
160
160
Mn K Na Ca Mg Mn K Na
10 156 188 - - >99 27 43
10 156 188 - - >99 27 43
0.72 - ... 96 - -
0.72 .... 96 ..
25 380 - 0 0 28 8
25 380 - 0 60 28 16 -
25 380 6 0 28 18
0 - - -
16
Leachate
Type-
*
R
R
R
R
R
R
R
R
*R " Rax leacnate
Reference
17,18,176
19,20
44,45,73
b3,S4,97
134
134
151
229
Oxldant
°3
Cl
°3
NaOCl
NaOCl
NaOCl
NaOCl
CI2
C12
Clf
CafOCl).,
Ca(OCl)'
CifOCO?
Ca(OCl),
CalOCllJ
°3 2
°3
KHnO,
KMnOj
KMno'
KMnO*
KMnO:
KMnO?
KMnO;
KMno:
KMnOj
KMnOj
NaOCl
liaOCl
NaOCl
HaOCl
°3
TABLE B-5.
Dose, mg/li
100 9 t-30 mm
400-1540
10-10,000
1.2-1.51 0,
9 4 l/min.
T« 3 hrs
3400 as
HaOCl
3000 as
NaOCl
2500 as
NaOCl
1600 as
NaOCl
400
800
1200
1540
1000
2000
4000
8000
12,000
15,000
T=| hr 9
Q=26mg03
mm
t=4 hr 9
Q-26mg03
mm
10
25
50
100
500
1000
2500
5000
7500
10.000
200 as
SOO as
C12
1000 as
2000 as
Cl,
2
24 9 r-4hrs
Bench- Scale
PH
5.3
7.0
7.0
8.8
8.4
8.4
7.6
7.6
2.2
2.0
1.8
1.6
8.0
8.0
8.2
9.0
9.9
10.2
7 4
7 4
6.0
6.0
6.0
6.0
6.0
6.0
6.0
6.0
6.0
6.0
-
.
_
.
8.0
Experimental Data
COO, mq/l TOC, nra/1 Removal. » Sludae
6.9
7.0
5.8
_
9.8
9.5
8.9
8.9
7.0
7.0
7 0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.8
7.5
5.8
5.8
5.8
5.8
5.8
5.8
5.8
5.8
5.8
5.8
-
.
_
.
14.000
340
10.650
670
330
320
270
290
340
340
340
340
1500
1500
1500
1500
1500
1500
7160
7160
10,900
10,900
10,900
10,900
10,900
10,900
10,900
10,900
10,900
10,900
-
.
.
7600
9200 5200 2700 34 48
-260 - - 25 9 1200 - 6
8500 - - 20 9 - 110 9
10,000 500 mg/1
300 250 120 48
220 - - 33
260 - - 19
120 - - 56
90 - 69
300 - - 13 - 4.5
290 - - 15 - 7.0
260 - - 24 - 5.0
320 - - 5.9 - 7.3
1400 - - 6.7-3
1400 - - 6.7-3
1100 - - 27-3
760 - - 49-4
900 - - 40-4
1000 - - 33-5
6800 - - 5.0-0
4500 - - 37-0
10,800 - - 1-40
10,700 - - 1.8 - 45
10,350 - - 5.1 - 50
10,300 - - 5.5 - 60
9800 - - 10 - 120
9700 - - 11 -
9600 - - 12
9350 - - 14
9100 - - 17 - -
8900 - - 18
1750 1590 - 9.1
1750 1510 - 14
1750 1420 - 19
1750 1360 - 22
6300 - 17
Leachate
R
D (1-25)
R
g
g
g
g
D (1:25)
D (1:25)
0 (1:25)
0 (1:25)
D (1:1)
D (1:1)
D (1 1)
0 (1 1)
D (1 1)
0 (I'l)
R
R
R
R
R
R
a
R
R
R
R
R
R
R
R
R
R
Data not given
* R - Raw leachate
B • Biologically treated effluent
0 * Diluted raw leachate
162
-------
TABLE B-6. Bench-Scale Experimental Data for COD and TOC Removal for the Physical Treatment Processes
Reference
44,45,70
207
207
Process*
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
IXH"
AC**
IX(M1xed
Resin)
AC
IX(-)
Test
_
Column
Column
Column
Column
Column
Batch(2g/l)
Batch! 10g/l)
flatch(4g/1)
Batch(2g/l)
Batch(10g/l)
Leachate
Type
Raw
Raw
Raw
Raw
Raw
Raw
Raw
Raw
Raw
Raw
Raw
Raw
AL
Effluent
AC
Effluent
IX(-)
Effluent
IX(-)
Effluent
IX(-)
Effluent
AL
Effluent
AL
Effluent
AL
Effluent
AL
Effluent
AL
Effluent
AS
Effluent
AS
Effluent
IX
Effluent
AS
Effluent
AS
Effluent
Influent
Concentration,
mg/1
5
S
5
5
5
S
8
8
8
8
8
8
8
8
5
5
5
8
8
8
6
pH
.5
.5
.5
.5
.5
.5
.0
.0
.0
.0
.0
.0
.8
.8
.5
.5
.5
.8
.8
.8
.2
8.8
7
5
8
7
2
.7
.0
.4
.3
.9
COO
..
-
-
-
.
_
.
.
_
-
-
.
_
-
_
_
.
500
500
500
500
500
180
180
115
185
185
TOC
13,000
13,000
18,500
18.500
13,000
13,000
13,000
13,000
18,500
18.500
13,000
13,000
214
48
133
119
143
200
200
200
200
200
_
_
'
-
-
Removal, (
COO
.
.
-
-
.
_
_
_
.
.
-
_
.
.
_
.
_
6
59
41
48
74
36
68
>99
10
19
TOC
70
75
56
59
85
88
92
93
89
60
93
94
95
86
97
94
94
31
43
26
43
71
KP-98 Membrane
KP-98 Membrane
KP-98 Membrane
KP-98 Membrane
NS-100 Membran
NS-100 Membran
KP-98 Membrane
KP-98 Membrane
KP-98 Membrane
KP-98 Membrane
NS-100 Membrane
NS-100 Membrane
NS-100 Membrane
NS-100 Membrane
NS-100 Membrane
NS-100 Membrane
NS-100 Membrane
Duolite A-7
Amberllte IRA-93
Amber 11 ts XE-299
Duolite A7
GAC (40x48)
Comnents
P-600 psig; Flux=5.5 gpd/ft2
P-1500 psi; Flux«8.9
P-600 psi; Flux=3.7
P-1500 psi; Flux«6.2
P-600 psi; Flux-7
P-1500 psi; Flux-11
P-600 psi: Flux-6.1
P-1500 psi; Flux-10
P-600 psi; Flux-3.9
P-150 psi; Flux-7.1
P-600 psi; Flux-7. 3
P-1500 psi; Flux-12.5
P-600 psi; Flux-9.8
P-600 psi; Flux-12.5
P-600 psi; Flux-12.0
P-600 psi; Flux=12.4
P-600 psi; Flux" 11. 9
8
HP
Oowex 50Wx8 H* and Oowex 1x8 OH"; t • 1 hour
Dowex 50Ux8 H* and Oowex 1x8 OH'; r - 1 hour
.
-
-
T - 30 mm. Used
Oowex 50Ux8 H*;
Oowex 50Wx8 H ;
2g/l IX Effluent
T - 1 hour
T - 1 hour
*RO - Reverse Osmosis
IX - Ion Exchange; (-) - anionic exchange resin
AC • Activated Carbon Adsorption
"Removal after 50 bed volumes
psi • 6.895 kN/m'.
gpd/ft2 - 0.041
163
-------
TABLE 8-7. Freundllch Isotherm Parameters for Activated Carbon Adsorption
Reference
44,45.70
53,54,97
134
143
151
207
229
178,179
28
* R 'Raw
RD - Raw
AC Type J Size
GAC
GAC
GAC
GAC
GAC
GAC
GAC;40x48
GAC;40x48
GAC;6xl4
GAC;6xl4
GAC;6xl4
GAC;6xl4
PAC;325 mesh
PAC
PAC
PAC
PAC
PAC
PAC
PAC
GAC;0.9 mi
SAC; 12x40
GAC; 12x40
GAC; 10x30
GAC; 12x40
GAC; 12x40
GAC;10x30
GAC; 12x40
GAC; 12x40
GAC; 12x40
Diluted
AS • AS Effluent
8V • Bed Volumes
Test
Batch
Batch
Batch
Batch
Batch
Column
Column
Column
Column
Column
Column
Column
Batch
Batch
Batch
Batch
Batch
Batch
Batch
Batch
Batch
Batch
Batch
Batch
Column
Column
Column
Column
Column
Batch
AF -
C >
B+C •
gum/ft2"
C0.m9/l *.
_
630
830
540
540
330
320
270
290
5000
508
344
232
594
192
-
184
6000
'
2990
2950
2930
3000
3000
2960
1000
3000
1010
Freundllch Isoth
~USS
mgCOD ,, mgCOD
gA!T~ "n'gAT7mq7T
.
520 0.93-1.7
261 0.70-2.3
-
-
-
-
-
-
-
2500 9.5
550 1 .4
600 2.5
ISO 0.98
800 2.2
600 5.9
-
540 1.57
-
-
340 3.2
300 3.0
200 2.6
.
.
.
.
0.14
em Parameters
TOJ
V"*' ***&
13,800 46
395 300
120 68
225 174
320 102
120 38
210
210
140
130
76
76
-
153 165
98 230
63 130
160 140
65 165
2000 144
-
-
4200 200
,
-
_
_
_
.
1/n rcgyrc Leachate
""•gAC/mg/l Type'
0.75-1.2 R
1.9-12 R
0.81 RD
AF(aerated)
AF
RO
AL
AL
AS
AS
AS
AS
R
1.1 C
2.5 B+C
2.4 B+C
0.97 C
2.9 B+C
2.7 R
AS
C(03)
0.60 R
C
C
C
C
C
C
B
C
B
Comments
Older leachate
Diluted leachate
Breakthrough 9 200 BOD
T-0.7 ntin; Max. CODSTOC
Ran • 671; After 50 BV-
561
T-3.7 min; Max. COOSTOC
Rem • 861; After 50 BV -
74%
T-15 min; COO Rem.=70J;
TOC Rem.-78J
T-15min;COD Rem.=47I;
TOC Rem.-75J
T-15 min; COD Rem.-52J;
TOC Rem.-53S
T-15 m1n; COD Rem.-55I;
TOC Rem.-53I
UV-Nuchar C-I90-N
CODeff-3420 mg/1;
43! removal; 4 g/IAC
Love Canal
Flltrasorb 400, 1050-
1200 m^/g y
UV-G Nuchar, 1100 »r/g
Hydrodarco, 650 m^/g
22: Removal C* 50 BV;,
T-4 min (1.55 gpm/ft^)
251 Removal C* 50 BV;
T-4 min (1.55 gpm/ft2)
141 Removal 0 50 BV;,
r-4 m1n (1.55 gpm/ft )
351 Removal 9 50 BV;,
T-4 m1n (1.55 gpm/ft/)
35% Removal l» 50 BV; ,
T-IO mm (0.65 gpm/ft^)
AF Effluent
Chemically Treated Effluent
Biologically
0.68 1/mZ-s
+ Chemically Treated Effluent
164
-------
TABLE B-8. Bench-Scale Experimental Data for Heavy Metal Removal for the Physical Treatment Processes
151
242,243
134
Process*
AC
AC
IX
AC
AC
AC
AC
AC
Test
Batch(8gy 1)
Continuous
(1 I/mini
Continuous
(1 1/mln)
Batch(2g/l)
Batch(8g/l)
Batch(16g/l)
Column
(v 4 mln)
Column
(t-26 mln)
Leachate
Type
RM
Raw
Raw
Raw
Raw
Raw
Raw
Raw
Raw
PH
7.1
7.5
7.6
7.6
7.6
7.6
a.3
Influent Concentration, rmj/t
26 - 30
0.026 0.07 0.24 22 0.23 0.13 0.69
0.082 0.13 0.28 14 0.18 0.21 0.78
66
66
66
40
40
Removal , t
>99
27 0 0 10 22 0 0
96 0 14 39 33 14 20
. 73 ...
. 96 ...
. 97 ...
. 65 - - -
. 66 - - -
Comments
PAO
GAC (6-14 mesh);
Glauconltlc sand
PAC (325 mesh)
PAC (325 mesh)
PAC (325 mesh)
SAC
GAC
•AC - Activated Carbon Adsorption (GAC • granular activated carbon; PAC • powdered activated carbon)
IX • Ion Exchange
TABLE B-9. Bench-Scale Experimental Data for Alkali and Alkaline Earth Metal Removal
for the Physical Treatment Processes.
Reference
151
242.243
407
Process*
AC
AC
IX
W*>
IXH
IXM
tx(Mtxed
Resin)
IX(M1xed
Resin)
IX(H1xed
Resin)
Test
Batch (8 g/t )
Continuous
(1 Vmin)
Continuous
(1 l/mln)
Batch (2 g/ 1)
_
Batch (4 g/ I)
Batch (12 9/1)
Batch (2 g/1)
Batch (4 g/ 1)
Batch (12 9/1)
Leachate
Type PH
Raw
R«w 7.1
Raw 7.5
Biologically 7.5
Treated
Effluent
Biologically 7.0
Treated
Effluent
Biologically 3
Treated
EffKent
Biologically 7.5
Treated
Effluent
Biologically 6
Treated
Effluent
Biologically 5.5
Treated
Effluent
Influent
Concentration, mq/1
Ca
178
152
181
30
30
30
15
15
15
Hg
100
132
164
18
18
18
15
IS
15
Hn K
25 380
7.2 280
6.1 364
100
100
100
65
65
65
Na
-
374
585
250
250
250
200
200
200
La
42
0
22
30
75
90 •
80
95
.
Remova 1 ,
Mg Hn
20 87
0 21
26 48
75
99
99
95
95
.
I
K
3
0
62
20
80
90
10
50
95
Ha
-
0
0
10
70
90
30
85
99
Comments
'PAC
GAC (6-14 mesh)
Glauconltlc sand
Oowex SOW H*i r • 1 hr
Oowex SOW H*; T • 1 hr
Dowex SOW Hf; t • 1 hr
Oowex SOU H* ; Dowex 10
Oowex SOW H*; Oowex 10
Dowex SOW Hf; Oowex 10
H"; T «1 hr
H"; T -1 hr
H"; i -1 hr
1 AC « Activated Carbon Adsorption {GAC * granular activated carbon; PAC * powdered activated carbon)
IX - Ion Exchange; (+) « catlonlc exchange resin
165
. 1992. 6"t8. 00 3/t0730
------- |