WATER QUALITY MANAGEMENT GUIDANCE
WTO 12-75-01
SLUDGE PROCESSING, TRANSPORTATION
AND DISPOSAL/RESOURCE RECOVERY:
A PLANNING PERSPECTIVE
DECEMBER 1975
ENVIRONMENTAL PROTECTION AGENCY
WATER PLANNING DIVISION
WASHINGTON, D.C. 20460
-------
-------
SLUDGE PROCESSING, TRANSPORTATION
AND DISPOSAL/RESOURCE RECOVERY;
A PLANNING PERSPECTIVE
Contract No. 68-01-3104
Project No. EPA-WA-75-R024
Program Element 2BH154
By
J. Michael Wyatt
Paul E. White, Jr.
Project Officer
Dean Neptune
United States Environmental Protection Agency
Planning Assistance Branch
Washington, D.C. 20460
Prepared for
WATER PLANNING DIVISION
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
-------
TABLE OF_CONTENTS
Page
Abstract vii
List of Tables viii
List of Figures xi
CHAPTER I INTRODUCTION 1
BACKGROUND 1
OBJECTIVES 1
PURPOSE 2
CHAPTER II STUDY CONTEXT 3
INTRODUCTION 3
GENERAL PERSPECTIVE 3
THE PLANNING APPROACH 6
CHAPTER III SOURCES AND CHARACTERISTICS OF MUNICIPAL 9
WASTEWATER TREATMENT PLANT RESIDUALS
INTRODUCTION 9
WASTEWATER CHARACTERISTICS 11
WASTEWATER TREATMENT TECHNOLOGIES 13
Primary Treatment 14
Primary Settling 14
Secondary Treatment 15
Trickling Filters 15
Activated Sludge 16
Chemical Addition to Primary Treatment 17
Tertiary Treatment 17
Chemical Addition to Secondary Treatment 17
Phvsical-Chemical Treatment 19
SUMMARY 21
CHAPTER IV SLUDGE HANDLING AND TREATMENT 25
INTRODUCTION 25
THICKENING 25
Gravity Thickening 25
Centrifugation 26
Dissolved Air Flotation 29
STABILIZATION 30
Anaerobic Digestion 30
Aerobic Digestion 33
Chemical Treatment 35
ii
-------
TABLE OF CONTENTS (CONT'D)
CONDITIONING 38
Chemical Addition 38
Elutriation 39
Heat Treatment 40
DEWATERING 41
Vacuum Filtration 41
Centrifugation 43
Sand Drying Beds 44
Lagoons 45
Pressure Filtration 47
SLUDGE DRYING AND REDUCTION 47
Incineration 47
Wet Air Oxidation 47
Heat Drying 51
Pyrolysis 51
Lime Recalcination 51
PERFORMANCE 52
ECONOMICS 52
Capital Costs 55
Gravity Thickening 55
Dissolved Air Flotation 55
Aerob*ic Digestion 55
Anaerobic Digestion 55
Incineration 56
Heat Treatment 56
Lime Treatment 56
Sand Drying Beds 56
Centrifugation 56
Vacuum Filtration . 56
Pressure Filtration 56
Operation and Maintenance Costs 57
CHAPTER V SLUDGE AND RESIDUE TRANSPORT 62
INTRODUCTION 62
PIPELINE 62
RAIL 65
TRUCK 65
BARGE 65
ECONOMICS 66
CHAPTER VI CHARACTERIZATION OF ULTIMATE DISPOSAL AND RESOURCE/ 79
RECOVERY METHODS
INTRODUCTION 79
SANITARY LANDFILLS 80
iii
-------
TABLE OF CONTENTS (CONT'D)
Introduction 80
Operational Characteristics 82
Waste Characteristics 82
Siting/Environmental Considerations 84
Suitability of Disposal 87
Management Agency Control and Monitoring Program 90
Control 90
Monitoring 91
Costs of Sanitary Landfilling 92
WASTE DISPOSAL PONDS 97
Introduction 97
Waste Characteristics 97
Operation Characteristics 98
Siting/Environmental Considerations 98
Suitability of Disposal 100
Management Agency Control and Monitoring Program 100
Control 100
Monitoring 103
Cost of Waste Disposal Ponds 104
SLUDGE RECYCLING 104
Introduction 104
Waste Characteristics 107
Operational Characteristics t 107
Siting/Environmental Considerations 109
Specific Location Criteria 114
Suitability of Disposal 115
Management Agency Control and Monitoring Program 115
Control 115
Monitoring 119
Costs of Sludge Recycling 122
LAND RECLAMATION 123
Introduction 123
Waste Characteristics 124
Operational Characteristics 124
Siting/Environmental Considerations 125
Suitability of Disposal 126
Management Agency Control and Monitoring Program 127
Costs of Land Reclamation 127
OCEAN DISPOSAL 128
Introduction 128
Waste Characteristics 129
Operational Characteristics 129
Siting/Environmental Considerations 131
Suitability of Disposal 133
iv
-------
TABLE OF CONTENTS (CONT'D)
Management Agency Control and Monitoring Program 135
Control 135
Monitoring 136
Costs of Ocean Disposal 137
RESOURCE RECOVERY METHODS 138
Introduction 138
Incineration 140
Heat Drying 141
Pryolysis 143
Lime Recalcination 146
Composting 146
Sludge Recycle/Marketing 149
CHAPTER VII EVALUATION PROCEDURES, CRITERIA, AND CONSTRAINTS 158
INTRODUCTION 158
SELECTION OF ALTERNATIVE RESIDUAL WASTE HANDLING PROCESSES 158
EVALUATION CRITERIA AND CONSTRAINTS OF ALTERNATIVE RESIDUAL 163
WASTE HANDLING AND DISPOSAL/REUSE PLANS
Economic Parameters 163
Environmental Parameters 167
Water 169
Air 170
Land 170
Flora and Fauna 171
Asethetics 171
Public Health 171
Community Impact 171
Resource Conservation 171
Feasibility Parameters 172
Financial Feasibility 172
Public Acceptability 172
Land Use Compatibility 175
Ease of Implementation 175
Performance Parameters 175
Effectiveness and Reliability 175
Adaptability 177
Calamity Resistance and Performance 177
CHAPTER VIII MANAGEMENT OF A CONTROL AND MONITORING PROGRAM 181
INTRODUCTION 181
CONTROL PROGRAM 181
Permit System 181
Environmental/Effluent Quality Standards 182
Land Use Regulation 184
Disposal Charges 184
-------
TABLE OF CONTENTS (CONT'D)
MONITORING PROGRAM
Monitoring the Constructed Facility and Operation 185
Monitoring Parameters of Environmental Concern 185
APPENDIX A COST EFFECTIVENESS ANALYSIS GUIDELINES A-l
vi
-------
ABSTRACT
A methodology was developed in this report for use in the
evaluation of alternatives for the ultimate disposal of residual
wastes generated in municipal wastewater treatment plants. This
methodology considered technical, economic, social, and institu-
tional factors pertinent to a thorough review of alternatives.
Residual wastes generated in municipal wastewater treatment
plants were characterized. Handling and treatment processes for
the residual wastes were discussed and evaluated in light of
qualitative and quantitative changes to the residual wastes.
Liquid, gaseous, and solid sidestreams produced in residual waste
treatment were evaluated and rail, pipeline, barge, and truck
transport of residual wastes were analyzed.
Environmental, operational, and institutional constraints
to the use of ocean disposal, lagoons, sanitary landfills, sludge
recycling, and land reclamation were presented.
This report was submitted in fulfillment of RFP. No. WA75-R024,
Contract No. 68-01-3104, by Engineering-Science, Inc. under
sponsorship of the Environmental Protection Agency. Work was
completed as of 12 February 1975.
vii
-------
LIST OF TABLES
Table No. Title Page
III-l Trends in Production of Municipal Wastewater Sludge 9
III-2 Estimated Distribution of Publicly-Owned 10
Treatment Works
1II-3 Typical Composition of Domestic Sewage 12
III-4 Estimate of the Components of Total Solids in 13
Wastewater
III-5 Additional Sludge to be Handled with Chemical 18
Treatment Systems - Primary Treatment for
Removal of Phosphorus
III-6 Additional Sludge to be Handled with Chemical 19
Treatment Systems - Phosphorus Removal by
Mineral Addition to Aerator
III-7 Additional Sludge to be Handled with Chemical 20
Treatment Systems - Phosphorus Removal by
Mineral Addition to Secondary Effluent
on
III-8 Advantages of Physical-Chemical Treatment versus
Conventional Biological Treatment
III-9 Sludge Production Characteristics for Physical- 21
Chemical Treatment of Wastewaters
IV-1 Sludge Treatment Processes and Their Functions 26
IV-2 Occurrence of Thickening Methods in Sludge Treatment 27
IV-3 Concentrations of Unthickened and Thickened Sludges 28
and Solids Loadings for Mechanical Thickeners
IV-4 Centrifugal Thickening Performance Data 29
IV-5 Performance Data from Flotation Thickening . 31
IV-6 Properties of Digester Supernatant from Anaerobic 33
Digestion
IV-7 Anaerobic Digestion-Tank Capacity Requirements 34
IV-8 Characteristics of Sludge Gas from Anaerobic Digestion 35
IV-9 Typical Chemical Composition of Rar-T and Anaero'bically 36
Digested Sludge
IV-10 Chemical Composition of Various Sewage Sludges 37
IV-11 Characteristics of Aerobic Digestion Supernatant 38
from Seven Facilities
viii
-------
LIST OF TABLES (CONT'D)
Table No. Title
IV-12 Dosage of Chemicals for Various Types of Sludges 39
IV-13 Specific Resistance of Sludges 40
IV-14 The Relationship of Dewatering to Other Sludge 42
Treatment Processes for Typical Municipal Sludges
IV-15 Typical Rotary Vacuum Filter Results for Sludge A3
Conditioned with Inorganic Chemicals
IV-16 Results of Centrifugation of Sludges using a Scroll- ^4
Type Centrifuge
IV-17 Criteria for the Design of Sandbeds 45
IV-18 Air-Dried Digested Primary Sludge Cake 46
IV-19 Pressure Filtration Considerations 47
IV-20 Typical Filter Press Production Data 48
IV-21 Reduction Processes 49
IV-22 Wet-Air Oxidation Process Effluent 50
IV-23 Typical Analysis of Ash from Wet Oxidation Process 50
IV-24 Normal Quantities of Sludge Produced by Different ^3
Treatment Processes
IV-25 Sludge Processing Unit Performance 54
V-l Summary of Commercial Slurry Pipelines 63
V-2 Barge Characteristics 67
V-3 Annual Capital and Maintenance Costs for Barging 73
Operation (Ocean Disposal)
V-4 Towing Costs for Barging Operations (Ocean Disposal) 73
VI-1 Classification of Sanitary Landfill Materials 83
VI-2 Suitability of Various Municipal Wastewater Treatment 88
Plant Residual Wastes for Sanitary Landfill Disposal
VI-3 Suitability of Various Municipal Wastewater Treatment 101
Plant Residual Wastes for Disposal by Waste
Disposal Ponds
VI-4 Mineral Nutrients - Percent of Dry Sludge Solids 105
VI-5 Location of Sludge Application Boundaries in 114
Ontario, Canada
VI-6 Suitability of Various Municipal Wastewater Treatment 116
Plant Residual Wastes for Sludge Recycling/Land
Reclamation
ix
-------
LIST OF TABLES (CONT'D)
Table No. Title
VI-7 The Probable Available Form, the Average Composition 120
Range for Selected Agronomic Crops, and the
Suggested Tolerance Level of Heavy Metals in
Agronomic Crops when used for Monitoring Purposes
VI-8 Costs for Land Spreading Digested Sludge 122
VI-9 A Selection of Prohibited Wastes that Apply to 130
Wastewater Treatment Plant Residual Wastes for
Ocean Disposal
VI-10 Suitability of Various Municipal Wastewater Treatment 134
Plant Residual Wastes for Ocean Disposal
VI-11 Reported Sludge Heat Values 140
VI-12 Sewage Sludge Incineration Exhaust Gas Analyses 142
VI-13 Pyrolysis Product Yield 144
VI-14 Proximate Analysis of Pyrolysis Char 144
VI-15 Sludge Treatment Including Pyrolysis, Estimated 147
Capital and Annual Costs
VI-16 Recalcination of Lime Sludge from Lime Clarification 148
Process
VII-1 Sludge-Producing Unit Processes
VII-2 Costs and Effects Considerations of Alternative
Areawide Plans, Significant Effects
VII-3 Alternatives Evaluation Matrix
VII-4 Impacts Measured from Most Desirable to Lea'st
Desirable, on Environmental Factors to be
Considered in Planning for the Ultimate Disposal
of Residual Wastes
VII-5 Impacts Measured from Most Desirable to Least
Desirable, on Feasibility Factors to be
Considered in Planning for the Ultimate Disposal
of Residual Wastes
VII-6 Factors Other than Costs Normally Considered in
Selection of Wastewater Treatment and Sludge
Handling Unit Processes
VII-7 Impacts Measured from Most Desirable to Least
Desirable, on Permanence Factors to be
Considered in Planning for the Ultimate Disposal
of Residual Wastes
-------
LIST OF FIGURES
Figure Number Page
II-l Operative and Ultimate Disposal of Residual 4
Wastes: A Planning Perspective
II-2 A Method for Developing Alternative Residual 7
Wastes Management Plans
IV-1 Capital Costs for Solids Processing Facilities 58a, b
IV-2 Annual Operation and Maintenance Costs for 59a, b
Solids Processing Facilities
V-l Hydraulic Characteristics of Sludge Solids 64
V-2 Economics of Pipeline Transportation of 68
Digested Sludge Pipeline Installation Costs
vs. Capacity for Three Construction Zones
V-3 Economics of Pipeline Transportation of 69
Digested Sludge Capital Costs (Excluding
Installation) vs. Distance for Various Through-
put Levels
V-4 Economics of Pipeline Transportation of 70
Digested Sludge, Direct Operating Costs vs.
Distance for Various Throughput Levels
V-5 Economics of Rail Transportation (Not on a 71
Unit Train Basis)
V-6 Economics of Truck Transportation 72
V-7 Transportation Costs for Dewatered Sludges by 74
Dump Truck (20-25 cu. yd. Capacity) for 30% to
70% Solids (Specifically Experience at Chicago
MSD)
V-8 Economics of Dump Truck Transport of Sludge Ash 75
V-9 Maximum Number of Trips Per Year for Preset 76
Barge Sizes
V-10 Transportation Costs for Liquid Sludges by 77
Privately Owned and Contracted Towed Barge
on Inland Waterways (Specifically the Tennessee
River System)
VI-1 Capital and 0/M Cost for Sanitary Landfills 93
VI-2 Comparative Cost (1966) of Sludge Disposal by 94
Various Methods for City of 10,000 Inhabitants
VI-3 Comparative Cost (1966) for Sludge Disposal by 95
Various Methods for City of 100,000 Inhabitants
xi
-------
LIST OF FIGURES (CONT'D)
Figure Number Page
VI-A Comparative Cost (1966) of Sludge Disposal by 96
Various Methods for City of 1,000,000 Inhabitants
VI-5 Comparative Economics of Transporting Digested Sludge 139
for Ocean Disposal
VII-1 Residual Waste Processing and Disposal/Reuse 159
Alternatives
VII-2 Sludge Handling Process Matrix 160
xii
-------
CHAPTER I
INTRODUCTION
BACKGROUND
A review of the Federal Water Pollution Control Act Amendments of 1972
(the Act) and the associated legislative history clearly indicates the Con-
gressional intent to eliminate as much as possible pollutant discharges to
receiving components of the environment. The basic waste treatment process
consists of separating contaminants in a way that is acceptable to local,
State, and Federal regulatory agencies. Proper ultimate disposal or reuse of
residual wastes is essential so that usable environmental components such as
surface or ground waters will not be needlessly contaminated and that pollut-
ants are not continuously and directly recycled into water supplies, food
chains, and other cycles.
At the present time, solids handling and other ultimate disposal opera-
tions are probably the most troublesome problems in treatment plant opera-
tions, partly because they have had the least attention. The problem is
becoming more critical since residual waste volumes are increasing with
higher treatment efficiencies and because the physical-chemical sludges and
other residual wastes from tertiary treatment operations are more difficult
to handle than some of the common biological sludges.
The basic approaches embodied in the Act require pragmatic and logical
steps to identify and control pollution sources, including:
(1) regional planning and management of the Nation1s waters which
will eventually identify all point and non-point sources of pollu-
tion within a given region, and establish effluent limitations on
these-sources of pollution;
(2) delegation of the permit programs to approved State programs after
guidelines have been prepared by the Federal Government; and
(3) control programs to determine compliance with the effluent limita-
tions and commencement of civil and criminal proceedings against
violators.
OBJECTIVES
Regional planning and management processes to be undertaken in the 208
planning process must be as inclusive as physically possible, both with respect
to known types of pollution and the limitations of treatment processes for
removing various pollutants. In addition, Sections 201(d), 201(e), 201(f) of
the Act specifically encourage resource utilization and resource recycling.
Within this encouragement lies the intent that planning processes carried out in
— 1 —
-------
fulfillment of Sections 201, 208, and 303 recognize and promote, where
possible, areawide implementation concepts of residual waste management.
Under subsections (J) and (K) of Section 208(b)(2) of the Act, 208
planning and management agencies must address "a process to control the
disposition of all residual waste generated in such area which could affect
water quality; and a process to control the disposal of pollutants on land
or in subsurface excavations within such area to protect ground and surface
water quality." In addition, Section 201(d)(4) of the Act requires in 201
facilities planning consideration of "the ultimate disposal of sludge in a
manner that will not result in environmental hazards." It therefore is also
the concern of 208 planning agencies that facilities plans already made and
either presently under construction or proposed for construction within the
twenty-year 208 planning time framework be incorporated in the overall 208
plan which is to include residual waste disposal control.
The objectives of 208 planning in terms of residual waste management and
control must then consider not only the disposal of residual wastes in an
environmentally acceptable manner but also the utilization of these wastes as
a resource where possible.
PURPOSE
The purpose of this report is to provide information to 208 planning
agencies regarding the sources, characteristics, treatment methods, trans-
portation modes, and ultimate disposal processes available for use in the
planning area. Information is also provided on ways in which residual
wastes may be utilized or recycled as a resource. This information is pro-
vided in a manner conducive to its utility in the evaluation and formulation
of alternative plans and the selection of the preferred plan under guidelines
developed by the Environmental Protection Agency for use in the 208 planning
and management process.
This report does not provide criteria for the construction grants
program.
- 2 -
-------
CHAPTER II
STUDY CONTEXT
INTRODUCTION
Within a 208 planning area there are a multitude of interacting
constraints and criteria dealing with municipal wastewater treat-
ment and the ultimate disposal or reuse of the resultant residuals.
The 208 planning agency will be faced with numerous options of both
approaching and conducting the required overall 208 plan develop-
ment and the integration of the various sub-plans (i.e. wastewater
treatment, non-point source controls, ctormwater management, land
use, etc.).
Residual waste management planning within the 208 effort must
not only be coordinated with the other sub-plans, but it must also
be aware of and responsive to other planning programs and present
and proposed future activities within the 208 planning area. A
major part of residual waste management planning must also consider
such concerns as resource conservation (e.g. energy, materials, re-
cycling), impacts upon socio-economic systems (e.g. transportation,
public health), and implementation of planning programs (e.g.
feasibility, performance, institutions).
A general perspective of residual waste planning is depicted
in Figure II-l. The basic components of the planning process,
shown in Figure II-l as the blocked areas, have been discussed in
this report document in light of their interrelationships one with
the other as well as the various planning considerations mentioned
above.
The following portions of this chapter are devoted to the over-
all understanding of this perspective and the utilization of this
report document as a pragmatic approach to the development and
evaluation of municipal wastewater treatment residuals generation,
handling, transport, and ultimate disposal or reuse.
GENERAL PLANNING PERSPECTIVE
Implicit in the general planning perspective shown in Figure
II-l is the essence of two major, yet separate, starting points in
the planning process. They are:
(1) given an existing wastewater treatment facility or
facilities with the attendant residuals generation
and processing, what are acceptable (i.e. capable of
meeting various constraints) disposal or reuse options
available for consideration and selection, or
- 3 -
-------
FIGURE n-l
OPERATIVE AND ULTIMATE DISPOSAL
OF RESIDUAL WASTES'
A PLANNING PERSPECTIVE
GIVEN A RAW WASTEWATER AND NEED
FOR ULTIMATE DISPOSAL OF RESIDUAL WASTE
ACCEPT FACILITY
RAW WASTEWATER
WASTEWATER TREATMENT
AND RESIDUALS HANDLING
FACILITY OR FACILITIES
TRANSFORM
PROCESSES
INSTITUTIONAL
CONSTRAINTS
RESIDUAL WASTE
LA
ULTIMATE DISPOSAL METHOD
L-L
1
I
TECHNICAL,
ENVIRONMENTAL,
SOCIAL,
ECONOMIC,
CONSTRAINTS
REJECT
DISPOSAL
METHOD
I— — —-
GIVEN CONSTRAINTS
— AND NEED FOR
WASTEWATER TREATMENT
ACCEPT
DISPOSAL
METHOD
NOTE:
.PATHWAY FOR A PLANNED FUTURE WASTEWATER
TREATMENT FACILITY WITHIN GIVEN CONSTRAINTS.
PATHWAY FOR AN EXISTING WASTEWATER
TREATMENT FACILITY WITHIN GIVEN CONSTRAINTS.
-4-
-------
(2) where wastewater treatment is needed and given
natural and cultural constraints applicable in the
planning area, what is the most suitable wastewater
treatment facility available which allows the disposal
or reuse of the resultant residuals in an acceptable
option?
In the first situation (pathway) cited above, the existing
wastewater treatment facility is generating a known quantity and
quality of residual wastes. Federal, State, and local guidelines
and regulations help define the ultimate residual waste disposal
options available to that facility. These disposal options, by
virtue of regulatory and environmental, social, and economic
constraints, will then have restrictions as to the quantity and
quality of residual wastes they can accept. By a comparison of
the disposal methods' qualities and quantities of residual wastes
they can handle with the known values from the wastewater treat-
ment facility, the facility can either utilize the disposal methods
available or further treat and transform the residual wastes to
qualities and quantities amenable to the available disposal methods.
The second situation (pathway) is essentially an integration
process. A planning area will have acceptable ultimate disposal
methods, again constrained in quantities and qualities which they
can handle by virtue of regulations and environmental, social,
and economic factors. The choice of the type of wastewater
facility processes will then be influenced by comparing predicted
quantities and qualities of residual wastes from a variety of
treatment processes to those of the acceptable and available ulti-
mate disposal methods. In this case, the quantities and qualities
of residual wastes from various wastewater treatment processes
can be modified by both raw wastewater modification, such as
industrial pretreatment, and by residual waste treatment and trans-
formation processes.
Traditionally, the planning process for residual waste
management has been the first situation; that is to select the
least-costly disposal method after the wastewater treatment facility
has been selected. However, a major effort of the 208 planning
process is oriented to a more coordinated and comprehensive review
including the assessment of residuals disposal on areas such as
non-point source pollution and land use planning. The advantage of
this integrative approach is that it allows for a more systematic
cost-effective evaluation of the overall wastewater treatment pro-
blem which includes residuals management. This approach assures a
more environmentally sound and cost-effective solution to the
planning area which can then be integrated into all other planning
activities within the area.
- 5 -
-------
THE PLANNING APPROACH
Having identified the basic components involved in planning
for residual waste disposal/reuse, it is essential to develop a
systematic approach to delineate alternative residual waste
management plans. This is particularly important because the
number of components involved in the decision process and the
large number of alternative elements within each component can
lead to an unwieldly number of possible disposal alternatives.
An additional consideration is the number and types of wastewater
treatment plants to be considered which may require the use of
several different disposal options within any one management plan.
Therefore, it is imperative that residual waste management planning
processes be formulated in such a manner as to clearly define the
limits and constraints under which the development of alternative
plans will be conducted and evaluated. Examples of limits or
constraints which should be identified initially would be the
desired level of aggregation of wastewater treatment plants
(i.e., individual sets of alternatives for each facility or regional
alternatives for several facilities) or the desirability/feasibility
of residual waste disposal/reuse options altering wastewater
facility process design of existing or proposed facilities. Without
a clear definition of the planning goals and, possibly more important,
the feasibility of the planning goals, the development of the
residual waste management alternatives could become an academic
exercise.
Figure II-2 is presented as an example method or approach for
a residual waste management planning process. It is intended,
primarily to show general study elements and their interrelation-
ships. Information flows are broadly identified along with the
types of information required as input to decision areas. [In
addition, this figure is utilized to show the types of information
to be found in this report.]
The following chapters of this report are intended to provide
a convenient starting point for developing the information necessary
in the residual waste management planning process. Chapter III
describes in some detail the various wastewater treatment processes
used and.provides general information about sludge quantities and
qualities generated from these processes. Chapter IV, similarly,
describes the sludge handling processes used in wastewater treatment
facilities and the changes in sludge quality and quantity that occur.
In addition, general capital and O&M costs are also given for these
processes. Chapter V presents the various sludge and residue transport
mechanisms utilized along with some general cost information. Chapter
VI describes in some detail the common and not-so-common ultimate
disposal methods available. Areas discussed include operational
characteristics, siting criteria, monitoring provisions, and general
- 6 -
-------
FIGURE 11-2
CO
Q.
H
UJ
UJ
^f
^J
ff\
1
_l
CO
UJ
cr
UJ
i
UJ
<
o
2
n
o
— i
UJ
UJ
0
or
e
Q
O
X
t
2
<
in
0 |
(O
§1
_JD
IA
1
"o
3
•o
(O
CO
£ .1
0 °
« S
0 g
* £
o:
— O
° w
« R
£ .«
t "S
4) in
E °
S °
£°-
stewoter
sting one
2 X
> UJ
1
o in
'c ~
^ °
'
O)
«/>
1
Q
0>
J3
1
£
c
f
TJ
'in
(T
•*-
O
£
§
o
in
c
O
'•s.
O
•o
U
p
Q.
c
.a
X
UJ
o
'o
1
•fe
f>
o
.t
!o
"a
1
m
c
g
JO
c
o
I
~o
0
2
m
a
>< s
^1
H-
O "O
E §
s I
fc 1
§ S r
jc L- a>
»•£*
s si
"5 4)
O •> in
o. in o
in o ^
O 03
5§1
woo:
|
c
o
E •
E •>
o 2
S 8
^1
1
1
|
i
- _ j
M
C
n
c
o
o
o
T3
2
to
o
a>
O
'Jo
o
Ot
c
55
«
•o ot
^.E
Ul
>> 1
§ a
O ?
'
"^
»
t>
o
•*
T3
•w
°=
in
'in
"5
c
~
-Q
'in
0
s.
'o
tfl
o
"o
c
1
'
in
O
i
«
a:
S
<0
Q
n
'§
c
•>
Ti
in
0
a.
O
m
n-
1
3
&
~m
—
election
V)
c
Si
1
u.
t
Alternativ
Management
•*-
•*- to
i*
o. o
O 3
•» 3 2
s s §
10
o
2 'in in
111 a: _g
» „ °-
•— .2
| £ |
' < o
" £
O o 5
- 7 -
-------
costs. Chapter VII presents an alternative plan evaluation technique
based on the cost-effective guidelines promulgated by EPA. Chapter
VIII describes some non-structural controls available in controlling
residual wastes problems and some general guidelines to consider in
setting up a monitoring program for residual waste management facilities.
It must be recognized that the information presented in this
document may, in some cases, be only of general utility and not directly
applicable to the planning area under consideration (e.g. transportation
costs, land application sludge loading rates, etc.). Where the desire
of the 208 planning agency is to develop site-and area-specific informa-
tion for inclusion in the final residual waste management plan selection,
local data should be used when available. The data presented in this
document would then be used to verify local data or as primary source
information if local data were unavailable.
- 8 -
-------
CHAPTER III
SOURCES AND CHARACTERISTICS OF MUNICIPAL
WASTEWATER TREATMENT PLANT RESIDUALS
INTRODUCTION
As the United States moves toward the goals and policies described in
Section 101 of the Federal Water Pollution Control Act Amendments of 1972,
publicly-owned treatment works (POTW's) are required to meet by July 1, 1977,
or July 1, 1978 (for new construction), secondary treatment as defined in the
Federal Register (Ref. III-l). In addition, by Sections 201(g)(2)(A) and
301(b)(2)(B) of the Act, POTW's are to provide by July 1, 1983, the applica-
tion of best practicable waste treatment technology.
The application of wastewater treatment technologies to meet these
requirements is anticipated to generate substantial amounts of municipal
wastewater treatment plant sludges which must be handled yearly as shown in
Table III-l. Realizing that sludge handling absorbs 35 percent of the capi-
tal costs and 55 percent of the annual operation and maintenance costs of a
wastewater treatment plant, these projected increases in sludge production
will mean considerable expenditures of money (Ref. III-2). Every effort must
be taken by 208 planning and management agencies to see that the expenditures
necessary for sludge handling and disposal are made wisely.
TABLE III-l
TRENDS IN PRODUCTION OF MUNICIPAL WASTEWATER SLUDGE
Sludge Type
Primary (0.12 lb/ cap-da)*
Secondary (0.08 Ib/cap-da)
Chemical (0.05 Ib/cap-da)
TOTAL
1972
Population
(million)
145
101
10
Dry tons**
per year
3,170,000
1,480,000
91,000
4,741,000
1985
Population
(million)
170
170
50
Dry tons
per year
3,720,000
2,480,000
455,000
6,655,000
* lb x 0.454 = kg
** ton x 0.908 = metric ton
Source: Ref. III-3
- 9 -
-------
There are an estimated 21,118 publicly-owned treatment works of varying
sizes in the United States using a variety of treatment and discharge pro-
cesses (Ref. III-A). These treatment works are shown in Table I[1-2 by treat-
ment process and location distribution. It has been noted that "most stream
segments in urban-industrial areas undertaking 208 plans will be water-
quality limited" (Ref. III-5). The import of this fact is that, of the close
to nine thousand publicly-owned treatment works on water-quality limited
segments, a potentially significant portion may have to provide treatment
higher than secondary before 1977 to provide the necessary protection of
water quality. This translates into greater volumes of sludge which must be
handled prior to ultimate disposal.
TABLE II1-2
ESTIMATED DISTRIBUTION OF PUBLICLY-OWNED TREATMENT WORKS
None
Primary
Pond
Trickling Filter
Activated Sludge
Extended Aeration
Secondary - Other
Land Disposal
Tertiary
TOTAL
Major Plants
(1 MGD or more)
WQLa
29
549
87
574
235
42
112
5
42
1,676
(sic)
ELb
32
366
50
382
219
29
77
3
30
1,188
EL-00C
3
62
7
57
35
4
13
—
4
185
Minor Plants:
(1 MGD or less)
WQL
944
828
1,800
1,367
872
686
518
58
169
7,242
EL
1,462
1,278
2,791
2,015
1,162
1,071
879
91
263
11,012
Total
2,467
3,022
4,728
4,338
2,488
1,828
1,586
157
504
21,118
(sic)
a) Plants located on water-quality-limited segments.
b) Plants located on effluent-limited segments.
c) Plants located on effluent-limited segments with ocean outfalls,
Source: Ref. III-4
The following sections of this chapter will provide a general background
as to the sources and characteristics of municipal wastewaters and modes of
treatment. Reference will be made to many of the design manuals and guide-
lines prepared by the Environmental Protection Agency (EPA) so that planners
may find more detailed explanations and examples helpful in the overall under-
standing of the integrated nature of the sludge disposal problems in their
planning areas.
- 10 -
-------
WASTEWATER CHARACTERISTICS
The nature of the physical, chemical, and biological characteristics of
municipal wastewaters is basic to the understanding of facilities expected
in 201 and 208 planning programs. The composition of raw sewage either anti-
cipated in future growth or in the expansion of existing facilities depends
upon the character of the municipal water supply, the industrial mix of the
community, the proportion of commercial to residential development, and the
nature of the residential community. The wastewater collection system,
particularly the control infiltration and inflow (see Ref. III-6), will
also influence the wastewater quality prior to treatment. As the waste-
water quality impacts upon the choice of wastewater treatment, so too will
it impact upon possible sludge disposal alternatives.
Table III-3 gives typical compositions of strong, medium, and weak
domestic sewage. These typical compositions are average, not only in light
of the above variables, but also because of variations in flows during the
day, week, and month. Estimates of the components of total solids in the
wastewater are given in Table III-4.
One area in which the 208 planning agency can directly affect wastewater
volume and quality and thus indirectly affect sludge handling and disposal
alternatives is that of pursuing programs to reduce domestic water consumption.
Previous studies have been made in an attempt to typify the average household
water requirements for a family of four (Ref. II1-8). By using in combination
such household devices as shallow trap toilets, flow control showers, one- and
two-flush valves with toilets, and faucet aerators, a substantial water savings,
on the order of 189 liters per day (50 gallons per day) per home, could be
realized. These five devices are commercially available, relatively easy to
install, and with proper minimum homeowner maintenance would provide sub-
stantial water savings to the homeowner without the necessity of more
sophisticated and potentially unreliable systems. The potential reductions in
water consumption would translate directly to reductions in water treatment
plant sludges. Where these sludges may be discharged to the sewer system for
treatment in the wastewater treatment plant or transported to a collection point
for common handling and disposal with wastewater treatment sludges, the reduc-
tion of these water treatment sludges would directly impact the overall basin-
wide sludge management alternatives available for consideration. Savings in
wastewater flows could also impact upon the choice of wastewater treatment
systems and hence upon sludge handling and disposal programs as well. These
savings could be significant in light of data from the Environmental Protection
Agency's 1973 "Needs" survey'for municipal wastewater treatment facilities.
This survey indicated that for 7605 reporting municipalities there was
correspondingly a total wastewater flow of 6.7528 x 10? m^/day (17,841 million
gallons per day), twenty percent of which was attributed to industrial sources
(Ref. III-9).
Pretreatment standards for industrial wastes discharging to publicly
owned treatment works have been promulgated by EPA (Ref. 111-10). Guidelines
for pretreatment recognize that one of several factors to be evaluated is
the "compatibility with the entire treatment works including sewers, pumping
stations, and sludge handling and disposal" (Ref. III-ll). Organic and
- 11 -
-------
TABLE III-3
TYPICAL COMPOSITION OF DOMESTIC SEWAGE
(All values except pettleable solids are expressed in ing/liter)
Constituent
Solids, total
Dissolved, total
Fixed
Volatile
Suspended, total
Fixed
Volatile
Settleable solids (ml/liter)
Biochemical oxygen demand, 5-day, 20 C (BOD,.)
Total organic carbon (TOC)
Chemical oxygen demand (COD)
Nitrogen (total as N)
Organic
Free ammonia
Nitrites
Nitrates
Phosphorus (total as P)
Organic
Inorganic
Chlorides*
Alkalinity (as CaCO-j)
Grease
Concentration
Strong
1,200
850
525
325
350
75
275
20
300
300
1,000
85
35
50
0
0
20
5
15
100
200
150
Medium
700
500
300
200
200
50
150
10
200
200
500
40
15
25
0
0
10
3
7
50
100
100
Weak
350
250
145
105
100
30
70
5
100
100
250
20
8
12
0
0
6
2
4
30
50
50
*Values should be increased by amount in carriage water.
Source: Ref. III-7
- 12 -
-------
TABLE
ESTIMATE OF THE COMPONENTS OF TOTAL SOLIDS IN WASTEWATER
Dry weight, gpcd
Component (grams per capita
per day)
Water supplies and ground water, assumed
to have little hardness
Feces (solids, 23%)
Urine (solids, 3.7%)
Toilet (including paper)
Sinks, baths, laundries, and other sources
of domestic wash waters
Ground garbage
Water softeners
Total for domestic sewage from separate
sewerage systems, excluding con-
tribution from water softeners 213
Industrial wastes 200+
Total for industrial and domestic wastes
from separate sewerage systems 413
Storm water 25+
Total for industrial and domestic wastes 438
* Variable.
+ Will vary with the season.
£ Will vary with the type and size of industries.
Source: Ref. III-7
inorganic compounds, both soluble and insoluble, discharged by industries
into municipal wastewater treatment plants may create significant upsets
in sludge digestion and handling processes (Ref. 111-12). Proper considera-
tion must therefore be given in the 208 planning activity either to correcting
present difficulties in sludge handling due to industrial inputs or to using
the guidelines mentioned above to insure no future problems. Monitoring of
industrial waters can be done using techniques suggested by EPA (Ref. 111-13).
WASTEWATER TREATMENT TECHNOLOGIES
Wastewater treatment technologies to achieve secondary and best
practicable treatment have been suggested by the Environmental Protection
- 13 -
-------
Agency (Ref. III-4). Additional guidance in the comparison selection of
cost-effective wastewater treatment technologies is available (Refs. 111-14,
111-15, and 111-16).
A manual has been prepared by EPA to assist in the performance evalua-
tion of existing wastewater treatment plants (Ref. 111-17). The 208 planning
agencies and their staffs can utilize this manual in the evaluation of sludge
handling problems and corrective measures to be taken in the operation and
disposal of wastewater treatment sludges.
Upgrading of existing wastewater treatment facilities may be an integral
part of the 208 plans. Guidance in this activity has been prepared by EPA
(Ref. 111-18). Additional supportive information and guidelines for
facilities planning under Section 201 of the Act have also been prepared by
EPA (Refs. 111-19, 111-20, 111-21, 111-22, and 111-23).
The following sections discuss the wastewater treatment technologies
commonly employed to meet requirements of treatment and discharge as pre-
sented in Reference III-4.
Primary Treatment
Primary Settling
Primary settling will remove about 25 to 35 percent of the BODt- and
from 60 to 65 percent of the suspended solids of the raw domestic wastewater.
Sludges removed in primary treatment are (1) solids removed by screening or
changed by comminution equipment, (2) grit and similar solids, (3) skimming,
usually pumpable, (4) settled sludge, usually 5 to 8 percent solids (the
solids loading is increased if there is a substantial amount of ground
garbage), and (5) waste sludge from secondary clarifiers (Ref. 111-24).
Screenings are materials such as rags, sticks, and garbage in t.ue raw
wastewater that are removed on bar racks or screens placed at the head end
of the treatment plant. The quantity of screenings captured in a waste-
water treatment plant will vary depending upon the size of screen opening.
Approximately 3.7 x 10~3 to 45 x 10~3 cubic meters of screenings per
1000 cubic meters (m /k-m3) of sewage are removed in openings of 1.3 to 5.1
centimeters and 37.3 x 10~"3 to 224.3 x 10~3 m3/k-m3 for openings of 0.2 to
1.9 cm [0.5 to 6.0 cubic feet of screenings per million gallons (ft3/MG) are
removed in openings of 1/2 to 2 inches and 5.0 to 30 ft-VMG for openings of
3/32 to 3/4 inches] (Ref. 111-25). Screenings have a moisture content of
85 to 95 percent and an organic content of 50 to 80 percent (Ref. 111-25).
Because of the high organic content, the screenings may either be incinerated
in a separate unit, in a skimmings incinerator, in a refuse incinerator, or
a dewatered sludge incinerator. They may also be ground by hannnermill
shredders and added to the sewage for later removal in sedimentation basins.
Heavy inert material or grit such as sand, silt, gravel, ashes, and
coffee grounds are selectively deposited in units installed at the head of
the wastewater treatment plant, either by velocity control in simple gravity
- 14 -
-------
settling chambers or classification of inert and lighter organic matters in
dissolved air flotation tanks. However, if septic wastewaters are expected,
aeration tanks should be covered to control odors. The quantity of grit
collected varies from 7.4 x 10~3 to 87 x 10" 3 m3/k-m3 with an average of
30 x 10" 3 m3/k-m3 (1 to 12 ft3/MG with an average of 4 ft3/MG) with a
moisture content of 14 to 34 percent (Ref. 111-25). Grit is often washed
after collection to reduce the organic concentration which may be as high as
50 percent of the total grit solids. The grit removed may be sent to a land-
fill and covered to guard against odors. "Well-washed grit has been used on
sludge drying beds, as a cover for screenings, and as a surfacing material
for walks and roadways. A few sewage treatment plants have incinerated grit
along with dewatered sludge. Being largely inorganic, most of the grit
solids are ultimately discharged with the incinerator ash" (Ref. 111-25).
Skimmings, consisting of all types of floatable materials collected from
sedimentation basins, normally vary in volume from 0.7 x 10" 3 to 52.3 x 10" 3
m3/k-m3 (0.1 to 7 ft3/MG), a moisture content of 60 to 90 percent, and a
volatile solids concentration of 90 to 95 percent (Ref. 111-25). Because
skimmings include high concentrations of grease and fibrous trash, the heat
value is considerably higher than screenings or grit.
Skimmings are currently disposed in one of four ways: (1) buried,
(2) pumped to digesters, (3) dewatered by mechanical equipment, or (4) incin-
erated. Burial of skimmings is simple, but they must be covered immediately
to control nuisance problems. Disposal to digesters is common, particularly
with completely mixed units. However, without thorough digester mixing the
skimmings may create a scum layer within the digester which leads to opera-
tional problems. Vacuum filtration dewatering would normally require prior
mixing with more readily drained materials or the use of a sludge precoat on
the filter. Incineration of just the skimmings may be a problem due to
development of high operating temperatures from the combustion of this highly
volatile and high energy-value material. The most common technique is to
incinerate the skimmings in the same furnace along with vacuum filter,
pressure filter, or centrifuge cake solids.
Grease recovery and reuse is not practical from wastewater treatment
plant skimmings because the volume of skimmings is small and the grease is
too contaminated with other materials. Purifying the grease is presently
too expensive and approval for domestic reuse by the Federal Drug Adminis-
tration would be doubtful (Ref. 111-25).
Secondary Treatment^
Trickling Filters
Conventional trickling filters use rock media on which biological
organisms are attached. As the wastewater effluent from the primary
settling process flows down through the filter, the biological growths
adsorb, absorb, and remove various pollutants. Biological activity results
- 15 -
-------
in cell synthesis which is a significant portion of the total sludge
produced. A portion of the organics or other pollutant matter will be con-
verted by biological synthesis into a solid. The excess solids not required
for carrying on the treatment process slough off the rock surfaces and
settle out in the final clarifier. The BOD 5 loading of the filter will
determine to a large extent the physical and biological characteristics of
the excess solids (Ref. 111-24). Standard-rate filters will generate about
0.25 pounds of solids per pound of BOD 5 removed, while high-rate filters
generate about 0.50 to 0.85 pounds per pound of BODc removed (1 pound =
454 grams). In recent years plastic media, usually polyvinyl chloride, have
been used as biological support surfaces for high BOD5 loadings per unit
volume. Solids production with these media increases to between 0.5 and 1.0
pound per pound of BOD^ removed. The solids from trickling filters thicken
in the final clarifier to 2 to 3 percent by weight, the denser solids
resulting from low-loaded filters.
The rotating biological contactor is a type of fixed media filter
similar in concept to a trickling filter (Ref. 111-26). A series of plastic
disks are mounted on a horizontal shaft and closely spaced providing a
relatively large area for biological growths. Wastewater flows through a
tank in a direction perpendicular to the slowly rotating disks which are
submerged to about three-eighths of their diameter (Ref. 111-24). "The
alternate contacting of the disks with the wastewater and the atmosphere
provides oxygen for biological removal of biodegradable pollutants from the
wastewater. Removals of 85 to 90 percent BOD 5 and suspended solids from
domestic wastewater have been reported. The solids slough off the disks and
are carried with the flow to a final clarifier. The quantity and physical
characteristics of the solids are comparable to those from trickling filters"
(Ref. 111-24).
Activated Sludge
Activated sludge processes use a suspension of aerobic microorganisms
to remove soluble and collodial organic matter. These organisms can vary in
type, concentration, and degree of agglomeration depending upon various
physical features of the plant, types of pollutants, and degree of pollutant
level. There are many modifications of the activated sludge process beyond
the scope of this study to investigate; however, the major processes are
discussed below.
High-rate aerobic activated sludge processes maintain organism sus-
pensions in the range of 2000 to 5000 mg/1 and are designed primarily for
the removal of carbonaceous BOD5. These processes are characterized by
high rates of excess solids production between 0.5 and 0.8 pound per pound
of BOD5 removed. Low-rate processes, on the other hand, are designed to
convert ammonia to nitrates. The types of organisms in this process have
a low reproductive (cell synthesis) rate with correspondingly much lower
excess solids produced per pound of ammonia (nitrogenous BODj.) oxidized.
It should be noted that variations in the design parameter of the
process can result in wide ranges in the character and amount of the excess
- 16 -
-------
solids produced. For example, in using oxygen rather than air, "the
concentration of the sludge drawoff from the final clarifier in the oxygen
system is about 1.0 to 2.5 percent; in the normal operation of an activated
sludge system using air the solids are usually not more than about 1 to 1.5
percent by weight" (Ref. Ill- 24). It has also been noted that the use of
oxygen in the activated sludge process can reduce up to 40 percent by weight
the amount of excess sludge to be disposed (Ref. 111-27).
Chemical Addition to Primary Treatment
Chemical treatment of raw wastewater can reduce BOD^ loads to an exist-
ing secondary plant and it can also precipitate and remove phosphorus from
the wastewater. Alum, iron salts, lime, or organic polymers are used to
flocculate and settle finely divided suspended solids and a portion of the
colloids in a primary clarifier. Because of its low cost, lime treatment
is frequently used. Depending upon the degree of phosphorus removal
desired, lime is added to raise the pH of the wastewater to between 9.5
and 11.5. The settled sludge is quite dense (5 percent solids at pH >11.5
and 11 percent solids at pH <11.5) and is usually dewatered without further
conditioning (Ref. 111-24). Table III-5 indicates the additional sludge to
be handled with chemicals in the primary treatment system. Sludges produced
in alum or iron coagulation can be digested. "No solubilization of the pre-
cipitated aluminum phosphate occurs, though some may occur when ferric
phosphate is reduced to the ferrous form in an anaerobic digester"
(Ref. 111-24). Care must be taken in anaerobically digesting high lime
sludge to prevent digester upset (Ref. 111-24). Lime treatment has the
advantage in that lime can be recovered in a recalcination facility, thus
reducing the amount of lime sludge for ultimate disposal as well as recover-
ing a resource.
Tertiary Treatment
Chemical Addition to Secondary Treatment
The requirement for low phosphorus levels in treated wastewater
effluents has seen the increased use of chemical addition to biological pro-
cesses to provide tertiary treatment. Alum or iron salts or lime can be
added to the activated sludge aeration basin, in a separate mixing basin
just prior to the final clarifier, or in the secondary effluent with sub-
sequent filtration or settling of the solids. The hydroxide produced coagu-
lates the finer particles in the biological suspension and improves the
clarification and settleability. Since the settled sludge is generally
denser, the total volume of sludge is not greatly increased although the
quantity of solids has increased. Tables III-6 and III-7 indicate the
additional sludge expected from chemical additions to a biological secondary
wastewater treatment facility.
A review of Tables III-5, III-6, and III-7 indicates that (1) lime
addition to the primary system creates the greatest increase in sludge mass,
and (2) the use of alum in the aeration basins creates the least increase in
sludge mass. However, the decisions as to what type of chemical to use and
its point of application, particularly in the upgrading of existing
- 17-
-------
m
i
H
PQ
H
O
2
O
H
H
H
O
4-1
C
/•-•s. QJ
+ OP
I 4J rH
+ MH
OJ C C
fn O M
x_x •r-J
•U t»
C -H M
o 13 co
vi TJ B
1 [ ^^ Ifu^
VI
PM
4-1
a
s~. 0)
4- 03
I W £
rH C C
<; o H
^-s -rt
4-^ r*>
B iH Vl
P rrj Cd
H T> a
,
O -H M
rJ -0 CO
»Trt £]
•^3 *r4
Vl
PM
rH
CO S*.
1 C Vl
C O cd
O -H B
u a *£
Q) PM
C
O Vl
0) -H 0)
60 4-1 4-1
TJ O (U
3 J^ 0
f~H 'O w
CO O Vi
M nj
PM PM
m
m •
OO CM ST
• i
in CM o
CM •
rH
O
CM •
CM CM CM
1 • 1
rH •
O
O
o
vo m
rH •* in
i • i
O -* rH
O
00 CM
m
0
o c^
in rH rH
1 • 1
O rH O
in rH •
CO CO
in
m •
CM m
o • i
m o
*
m
0)
C 60
cd c
S Pi
<4-l rH C
O CO O 4-1
0 -H ^ C CO
rH >rl 4J rH 0) 60 TJ
0) TJ 60 M 3 rH
CM rH
CO 1
«o
rH 0
CM
rH
O
O
0
r-~ m
VO rH
•* CO
CJN O
fs^
M
sr
o
o
o
o •>
co oo
vO 1
«o
m o
m
M
CM
O
m
oo o>
00 A
P** ^3
o
vO
0)
a 60
cd G
QJ cd
5d P^!
r*
*£*
^^^
,0
rH
O
O
O
CM OO
CM CO
O*i 1
•O
rH O
CM O
O
O
O
O vO
O CO
O 1
-0
CO O
CM O
cT
rH
O
o
0
<• oo
m co
CM 1
oo oo
CM !-•
VO
i-H
O
O
O
si- 00
CM rH
CM 1
•> CO
OO VO
vO
A
^J-
o
O
O
m •>
vo m
sfo
vD
CO
(U
C! 60
cd c
Q) cd
J£j ptj
C1
VH
^.^
rH
cd
00
CO
o
rH
rH
60
c
o
•H
rH
^
B
}_4
QJ
a.
co
»rj
C
3
O
P.
I
,0
rH
• •
QJ
4-1
O
^
CO
C
o
1
r*l
rH
CO
60
C
0
•H
rH
rH
's
)_l
QJ
a,
co
G
O
rH
rH
n)
60
II
O
Sd
rH
cd
60
oo
CM
1
M
M
M
.
QJ
Pd
aJ
o
M
3
O
CO
-------
TABLE II1-6
ADDITIONAL SLUDGE TO BE HANDLED WITH CHEMICAL TREATMENT SYSTEMS
PHOSPHORUS REMOVAL BY MINERAL ADDITION TO AERATOR
PI. J .-V ~
Sludge
Production
Parameter
Level of
chemical
addition
(mg/1)
Percent
sludge
solids
Ib/MG
gal/MG
Mean
Range
Mean
Range
Mean
Range
i i i
Al Addition to Aerator
Con-
ventional
Secondary
0
0.91
0.58-1. A
672
384-820
9,100*
7,250-12,300
i i i
With Al
Addition
9.4-23
1.12
0.75-2.0
1,180
744-1,462
13,477
7,260-20,000
i i K
Fe Addition to Aerator
Con-
ventional
Secondary
0
1.2
1.0-1.4
1,059
918-1,200
10,650*
10,300-11,000
i i i
With Fe
Addition
10-30
1.3
1.0-2.2
1,705
1,100-2,035
18,650
6,000-24,000
*Difference due to the fact that different plants were evaluated.
Source: Ref. 111-28
facilities, will be made considering not only the additional sludge mass
produced but also the sludge processing equipment available and the ease of
sludge handling and treatment.
Physical-Chemical Treatment
Physical-chemical treatment can be either a secondary or tertiary treat-
ment process depending upon the types and amounts of chemicals added and the
unit process employed. The type of treatment is non-biological using lime,
alum, or iron salts to coagulate phosphorus, heavy metals, and suspended
solids in raw or partially treated wastewaters. Lime has been particularly
effective in that it produces a dense sludge that thickens and dewaters easily,
it can be reclaimed by recalcination for reuse, and it is relatively inexpen-
sive. Following chemical coagulation, the wastewater may go to dual-media
(such as coal-sand) filters for suspended solids removal followed by activated
carbon columns for residual high molecular weight organic removal. Suggested
advantages of physical-chemical treatment versus biological treatment are
given in Table III-8.
- 19 -
-------
TABLE III-7
ADDITIONAL SLUDGE TO BE HANDLED WITH CHEMICAL TREATMENT SYSTEMS
PHOSPHORUS REMOVAL BY MINERAL ADDITION TO SECONDARY EFFLUENT
Sludge
Production
Parameters
Level of chemical
addition (mg/1)
Percent sludge
solids
Ib/MG
gal/MG
Mean
Range
Mean
Range
Mean
Range
Lime
Addition
268-450
1.1
0.6-1.72
4,650
3,100-6,800
53,400
50,000-63,000
Alum (Al444")
Addition
16
2.0
— *
2,000
*
12,000
— *
Iron (Fe444")
Addition
10-30
0.29
— *
507
175-781
22,066
6,000-36,000
* Not measured
Source: Ref. 111-28
TABLE III-8
ADVANTAGES OF PHYSICAL-CHEMICAL TREATMENT
VERSUS CONVENTIONAL BIOLOGICAL TREATMENT
(1) Less Land Area Requirement (1/2 to 1/4) Than Biological. Systems
(2) Less Sensitivity to Diurnal Variations (Greater Stability)
(3) Not Affected by Toxic Metals
(4) Potential for Significant Heavy Metal Removal
(5) Superior Removal of Phosphorus Compounds
(6) Greater Flexibility in Design and Operation
(7) Modular Design Capability
(8) Capability to Accommodate Increased Flows
Source: Ref. 111-29
- 20 -
-------
Disadvantages of physical-chemical treatment include an inability to
remove low-molecular-weight organics (sugars, alcohols, etc.) and higher
operating costs due to increased chemical usage. This requirement for
increased quantities of chemicals consequently results in an increase in the
total mass of solids to be handled and disposed. Since the solids generated
are denser, the volume of sludges to be handled, however, may not be any
greater than experienced in biological treatment systems. Table III-9 indi-
cates for specific chemical dosages the anticipated sludge production.
TABLE III-9
SLUDGE PRODUCTION CHARACTERISTICS FOR PHYSICAL-CHEMICAL
TREATMENT OF WASTEWATERS
Process Parameter
Chemical Dosage (mg/1)
Sludge Production
Wastewater (Ib/MG)
Chemical (Ib/MG)
Total (Ib/MG)
Slowdown Solids (gm/1)
Ferric
Chloride
(Fe^)
120
700
700
1400
13
Alym|
150
700
500
1200
3
Hydrated
Lime
460
700
6300
7000
120
Source: Ref. 111-29
SUMMARY
As new wastewater treatment facilities are designed or existing
facilities are upgraded to meet current and projected discharge requirements
of the Act, proper consideration as to the expected quantities and qualities
of sludge must be given. The previous sections of this chapter are intended
to serve as guidance to the 208 planning agency in the development of
general quantities and qualities of sludges generated for various types of
wastewater treatment technologies.
- 21 -
-------
CHAPTER III
REFERENCES
III-l 38 CFR 159 (August 17, 1973).
III-2 "Sludge Disposal: Are We Solving the Problem?", Presecan, N. L.,
Deeds and__Data, Water Pollution Control Federation (October 1971).
III-3 "Overview of Sludge Handling and Disposal," Farrell, J. B., in
Pretreatment and Ultimate Disposal of Wastewater Solids. Proceed-
ings of a Symposium, Rutgers University (May 21 and 22, 1974).
III-4 Alternative Waste Management Techniques for Best Practicable Waste
Treatment, U. S. Environmental Protection Agency, proposed for
public comment (March 1974).
111-5 Draft Guidelines for Areawide Waste Management Planning. Section
208, Federal Water Pollution Control Act Amendments of 1972. U. S.
Environmental Protection Agency (October 1974).
III-6 Prevention and Correction of Excessive Infiltration and Inflow
into Sewer Systems, A Manual of Practice, American Public Works
Association, Water Pollution Control Research Series 11022EFF
(January 1971).
III-7 Wastewater Engineering, Metcalf and Eddy, Inc., McGraw-Hill Book
Co., New York, N. Y. (1972).
III-8 A Study of Flow Reduction and Treatment of Wastewater from House-
holds, Bailey, J. R., Benoit, R. J., Dodson, J. L., Robb, J. M.,
and Wallman, H., General Dynamics, Electric Boat Division, EPA
Contract No. 14-12-428 (December 1969).
III-9 Reductions in Water Consumption and Flow of Sewage, Report to the
Congress, U. S. Environmental Protection Agency (June 1974).
111-10 40 CFR 128 - Pretreatment Standards.
III-ll Pretreatroent of Pollutants Introduced into Publicly Owned Treat-
ment Works, Federal Guidelines. U. S. Environmental Protection
Agency (October 1973).
111-12 Industrial Water Pollution Control. W. W. Eckenfelder, Jr.,
McGraw-Hill (1966).
111-13 Handbook for Monitoring Industrial Wastewater. U. S. Environmental
Protection Agency, Technology Transfer (August 1973) .
- 22 -
-------
CHAPTER III
REFERENCES
(Continued)
111-14 "Wastewater System Alternatives: What Are They...and What Cost?",
Monti, R. P., and Silberman, P. T., Water and Wastes Engineering,
(March 1974).
II1-15 A Guide to the Selection of Cost-Effective Wastewater Treatment
Systems, Bechtel Incorporated, for the Municipal Wastewater Systems
Division, U. S. Environmental Protection Agency, Contract No.
68-01-0973 (May 1973).
111-16 Municipal Sewage Treatment, A Comparison of Alternatives,
Battelle Memorial Institute, prepared for the Council on Environ-
mental Quality and the U. S. Environmental Protection Agency
(February 1974).
111-17 Procedures for Evaluating Performance of Wastewater Treatment
Plants, A Manual, URS Research Company, for the U. S. Environ-
mental Protection Agency, Contract No. 68-01-0107.
111-18 Upgrading Existing Wastewater Treatment Facilities, Process Design
Manual, U. S. Environmental Protection Agency, Technology Transfer
(October 1974).
111-19 Sulfide Control in Sanitary Sewerage Systems, Process Design
Manual, U. S. Environmental Protection Agency, Technology Transfer
(October 1974).
111-20 Suspended Solids Removal, Process Design Manual, U. S. Environ-
mental Protection Agency, Technology Transfer (October 1971).
111-21 Phosphorus Removal, Process Design Manual, U. S. Environmental
Protection Agency, Technology Transfer (October 1971).
111-22 Carbon Adsorption, Process Design Manual, U. S. Environmental
Protection Agency, Technology Transfer (October 1971).
111-23 Guidance for Facilities Planning, U. S. Environmental Protection
Agency (January 1974).
111-24 Municipal Wastewater Treatment Plant Sludge and Liquid Sidestreams,
Kalinske, A. A., U. S. Environmental Protection Agency, Contract
No. 68-01-0324 (draft November 1974).
111-25 A Study of Sludge Handling and Disposal, Burd, R. S., publication
WP-20-4, U. S. Department of the Interior, FWPCA (May 1968).
- 23 -
-------
CHAPTER III
REFERENCES
(Continued)
111-26 Application of Rotating Disc Process to Municipal Wastewater
Treatment, EPA Report 17070-DAM-11/71 (November 1971).
111-27 "Sludge Considerations of Oxygen Activated Sludge," Young, K. W.,
Matsch, L. C., and Wilcox, E. A., in Applications of Commercial
Oxygen to Water and Wastewater Systems, Malina, J. F., Jr., and
Speece, R. E., eds., The University of Texas at Austin (1973).
111-28 Sludge Treatment and Disposal. Process Design Manual, U. S.
Environmental Protection Agency, Technology Transfer (October
1974).
111-29 Physical-Chemical Alternatives to Biological Wastewater Treatment,
Keinath, T. M., presented at a short course entitled "Physical-
Chemical Treatment Technology," Environmental Protection Agency,
Southeast Water Laboratory, Athens, Georgia (February 14-18, 1972)
- 24 -
-------
CHAPTER IV
SLUDGE HANDLING AND TREATMENT
INTRODUCTION
Previous work has characterized the processes used and their functions
in the treatment of sludges as shown in Table IV-1. The following sections
of this chapter are devoted to a brief description of techniques and equip-
ment available to carry out the process functions.
THICKENING
Thickening of waste sludges removed from primary and secondary
clarifiers is desirable for several reasons, notably:
(1) the reduced volume of thickened sludge decreases the costs of
conveyance and ultimate disposal;
(2) fluctuations in sludge quality and quantity passing to sub-
sequent processes is lessened and less chemical conditioning
is necessary prior to further dewatering; and
(3) digester operation is improved because a higher solids loading
is attainable, bacterial digestion becomes more efficient,
heating requirements (in anaerobic digestion) are reduced, and
less volume of supernatant liquor is produced (Ref. IV-2).
The most common methods for thickening are mechanical gravity thickening,
air flotation, and centrifugation. The occurrence of these thickening
methods and the type of sludge for which they are generally applicable are
shown in Table IV-2.
Gravity Thickening
The most conventional approach to sludge thickening of either primary,
excess activated, or trickling filter sludges has been by the use of
mechanical gravity thickeners.
*
The concentrations expected from mechanical gravity thickeners for
various types and combinations of sludges are given in Table IV-3. The
quality of the thickener overflow is determined by the type and character-
istics of the sludge being thickened. "The overflow liquid from gravity
thickening of municipal primary and biological sludges has a suspended
solids content of about 150 to 300 mg/1 and a BOD5 of about 200 mg/1"
(Ref. IV-4). Table IV-3 indicates that better overall operation of a
gravity thickener can be obtained when mixed sludges are thickened rather
than when each type of sludge is thickened independently.
- 25 -
-------
TABLE IV-1
SLUDGE TREATMENT PROCESSES AND THEIR FUNCTIONS
Unit Processes
Functions
Thickening
(Blending)
Stabilization
(Reduction)
Conditioning
(Stabilization)
Dewatering
Heat Drying and
Reduction
(Stabilization)
- Water Removal
- Volume Reduction
- Post Process Efficiencies
- Blending
- Pathogen Destruction
- Volume and Weight Reduction
- Odor Control
- Putrescibility Control
- Gas Production
- Improve Dewatering or Thickening Rate
- Improve Solids Capture
- Improve Comparability
- Stabilization
- Water Removal
- Volume and Weight Reduction
- Change to Damp Cake
- Reduces Fuel Requirements for Incineration/
Drying
- Destruction of Solids
- Conversion
Source: Ref. IV-1
Centrifugation
Centrifuges may be used for thickening waste activated sludge or primary
sludges. However, because centrifugation of primary sludges can concentrate
the solids to approximately 25 percent, this process is usually considered a
dewatering step for primary sludges. The sludge cake of approximately 75 to
80 percent moisture contains a solids concentration of from 15 to 30 percent.
- 26 -
-------
TABLE IV-2
OCCURRENCE OF THICKENING METHODS IN SLUDGE TREATMENT
Method
Type Sludge
Other Pertinent
Considerations
Frequency of Usage
and Relative Success
Gravity
Gravity
Gravity
Gravity
Gravity
Gravity
(Elutriation)
Dissolved Air
Flotation
Dissolved Air
Flotation
Solid Bowl
Conveyor Type
Centrifuge
Disc Type
Centrifuge
Raw Primary
Digested Primary
Raw Primary and
EAS
Raw Primary and
EAS
Air EAS
Digested Primary
and EAS Mixture
Raw Primary and
EAS
Air EAS
Air EAS
Air EAS
Separate Air EAS
Thickening
Separate EAS
Thickening
Recirculation of
Air EAS to
Primaries
Direct Mixed Sludge
Thickening
Separate Primary
Sludge Thickening
Secondary Digesters
or Elutriation
Direct Mixed Sludge
Thickening
Separate Gravity
Thickening of
Primary
Separate Gravity
Thickening of
Primary
Separate Gravity
Thickening of
Primary
Increasing-excellent
results
Infrequent now; but
feasible
Decreasing-usually
poor
Some new installa-
tions-marginal
results
Essentially never
used-poor results
Many plants built-
requires flocculants
Rarely used
Increasing-good
results
Some limited use-
solid capture
problem
Some limited use-
data now being
accumulated
Note: EAS = Excess Activated Sludge
Air EAS - Excess Activated Sludge using Air rather than Oxygen
Source: Ref. IV-1
- 27 -
-------
TABLE IV-3
CONCENTRATIONS OF UNTHICKENED AND THICKENED SLUDGES AND SOLIDS
LOADINGS FOR MECHANICAL THICKENERS
Type of Sludge
Separate sludges:
Primary
Trickling filter
Modified aeration
Activated
Combined sludges:
Primary and trickling filter
Primary and modified aeration
Primary and activated
Sludge, percent solids
Unthickened
2.5-5.5
4-7
2-4
0.5-1.2
3-6
3-4
2.6-4.8
Thickened
8-10
7-9
4.3-7.9
2.5-3.3
7-9
8.3-11.6
4.6-9
Solids
loading
for
mechanical
thickeners,
Ib/sq ft/day
20-30
8-10
7-18
4-8
12-20
12-20
8-16
Note: Ib/sq ft/day x 4.89
sqm = square meters
Source: Ref. IV-3
kg/sqm/day, where kg = 1000 grams and
The centrate is relatively high in suspended, non-settling solids,
which, if discharged back to the waste treatment plant, would adversely
affect the removal of suspended solids for the final effluent. This
problem may be alleviated by the addition of a sludge coagulating/condition-
ing agent such as lime, ferric chloride, or organic polymers, albeit at an
increased cost (Ref. IV-5).
Centrifuges have substantial disadvantages such as high power costs,
complex maintenance, and the need for conditioning chemicals to provide
optimum solids retention (Ref. IV-2).
Horizontal scroll centrifuges can produce a 21 percent solids sludge
cake with unconditioned digested sludge and 25 percent solids cake from
- 28 -
-------
TABLE IV-4
CENTRIFUGAL THICKENING PERFORMANCE DATA
Type
of
Sludge
EAS
EAS
EAS (after
Roughing
Filter)
EAS (after
Roughing
Filter)
EAS
EAS
EAS
EAS
Centrifuge
Type
Disc
Disc
Disc
Disc
Basket
Solid-Bowl
Solid-Bowl
Solid-Bowl
Capacity
(gpm)
150
400
50-80
60-270
33-70
10-12
75-100
110-160
Feed
Solids
(%)
0.75-1.0
-
0.7
0.7
0.7
1.5
0.44-0.78
0.5-0.7
Under-
flow
Solids
(%)
5-5.5
4.0
5-7
6.1
9-10
9-13
5-7
5-8
Solids
Recovery
(%)
90+
80
93-87
97-80
90-70
90
90-80
65
85
90
95
Polymer
Require-
ment
(Ib/ton)
None
None
None
None
None
-
None
None
<5
5-10
10-15
Note: EAS = Excess Activated Sludge
gpm = gallons per minute
Source: Ref. IV-1
digested, heat conditioned, and thickened sludge with polymer conditioning
chemicals (Ref. IV-6).
The thickening performance of disc, basket, and solid bowl centrifuges
is given in Table IV-4.
Dissolved Air Flotation
Flotation thickeners are used primarily with waste activated sludge and
will generally produce a sludge with about four percent solids. Higher float
concentrations, averaging six percent and ranging as high as eight percent,
have been obtained with mixtures of primary and waste activated sludges
(Ref. IV-3). The use of polyelectrolytes can increase the solids collected
in a flotation thickener. However, these polyelectrolytes are expensive and
can add considerably to the overall cost of the thickening process.
- 29 -
-------
Table IV-5 Indicates the performance data for flotation thickening.
Flotation thickeners are more expensive and difficult to operate t"an
gravity thickeners. However, due to reduced retention times and subsequently
smaller tank volumes, they do offer the advantage of lower capital costs
(Ref. IV-2). Flotation thickening is also more reliable in thickening light
sludges which rise quickly and compact readily in flotation tanks but which
would become putrified in gravity thickeners before achieving the desired
concentration.
STABILIZATION
There are several methods available for stabilizing a conditioned and
thickened sludge. This section is devoted to a general discussion of these
treatment methods. Each method has its own advantages and disadvantages
and would be considered for use depending upon both the nature of the sludge
entering the treatment process, the mode of further treatment, and the rinal
disposal planned for the resultant treated sludge and by-products.
Anaerobic Digestion
Anaerobic digestion can be defined as the decomposition of organic
matter in the absence of free oxygen. The decomposition is accompanied by
gasification, liquefaction, stabilization, colloidal structure breakdown,
and release of moisture (Ref. IV-5). Generally, the digestion process is
not complete and intermediate products such as organic acids, ammonia,
methane, hydrogen sulfide, carbon dioxide, and carbonates are produced
(Ref. IV-5). Depending upon the initial volatile solids content, of the
sludge to be treated, anaerobic digestion can achieve a 60 to 70 percent
reduction in volatile solids. The purposes of anaerobic treatment
(Ref. IV-5) are generally to:
(1) prevent nuisance by decomposing organic solids to a more stable
form;
(2) reduce sludge volume by converting organic solids to gases and
liquids;
(3) reduce volume by concentrating the remaining solids into a dense
sludge;
(4) store sludge to accommodate fluctuations in wastewater flows and
to permit flexibility in subsequent dewatering operations;
(5) homogenize sludge solids to facilitate subsequent handling pro-
cedures;
(6) produce a more easily dewatered sludge; and
(7) reduce pathogenic organisms.
- 30 -
-------
TABLE IV-5
PERFORMANCE DATA FROM FLOTATION THICKENING
Sludge Type
Waste activated
Waste activated
Waste activated
Waste activated
Waste activated
Waste activated
Waste activated
Waste activated
Waste activated
Waste activated
Waste activated
Mixture*
Mixture*
Mixture*
Mixture*
Mixture*
Mixture*
Chemical
Flotation
Aids
Required
No
No
No
No
No
No
No
No
Yes
Yes
Yes
No
No
No
No
No
No
Loading
(Ib/sq ft/day)
10.0
11.3
11.7
11.8
12.3
18.5
20.0
25.3
14.0
20.0
48.0
18.2
22.8
23.5
32.8
18.6 (Primary)
+22.8 (EAS)
29.4 (Primary)
+17.3 (EAS)
Sludge Concentration
Feed
(%)
0.5-1.0
0.6-1.5
0.8
0.5
0.6
0.4
0.7
1.0
0.5
0.7
0.5
0.5
1.2
1.6
Thickened
(%)
4.1
4.0
4.6
5.5
6.5
4.0
4.5
4.6
3.0
3.0
4.0
7.3
8.6
6.0
7.3
5.3
7.0
Recovery
(%)
90.0
87.0
84.6
85.0
93.0
88.3
99+
83.4
85.0
85.0
95.0
91.0
85.0
87.0
94.4
*Mixture = Waste activated + primary
Note: Ib/sq ft/day x 4.89 = kg/sqm/day
- 31 -
-------
As high as possible a sludge solids feed concentration to the digester is
desirable (Ref. IV-5) because:
(1) it conserves heat due to the minimum amount of water present;
(2) it encourages microorganism efficiency because their food supply
is concentrated;
(3) it increases detention times;
(4) it minimizes supernatant volume returned to other treatment pro-
cesses; and
(5) it promotes the efficiency of subsequent dewatering steps.
High-rate digestion, by increasing the loading rates and thus decreas-
ing the detention times, has been employed primarily to reduce costs
associated with tankage. However, high-rate digested sludge resists com-
paction and effective liquids separation. Consequently, the supernatant
liquid has a high solids content. Table IV-6 compares the properties of
digester supernatant from standard and high-rate digestion. Table IV-7
gives an indication of digestion tank capacity requirements to be expected
for the anaerobic digestion of various biological treatment processes. The
return of supernatant to the head of the wastewater treatment process
results in an additional load on the system which causes treatment problems.
Unless the wastewater treatment plant is properly designed to handle this
additional load, the supernatant must be treated in a separate system,
usually an aerobic biological plant.
Digester gas given off in the process of anaerobic digestion may be
used to mix the contents of the tank or as a fuel for boilers and internal
combustion engines used for pumping sewage, operating blowers, and electri-
city generation. Gas production estimated on a per capita basis is about
0.3 to 0.6 cubic feet (8.5 x 10" 3 to 17 x 10~3 cubic meters) in an unheated
digester and from 0.6 to 0.8 cubic feet (17 x 10~3 to 22 x 10~3 cubic meters)
in heated digesters (Ref. IV-1). The digester gas has a heat value of
approximately 600 BTU/ft3 (5350 kilogram-calories/cubic meter) (Ref. IV-5).
If the hydrogen sulfide content of the gas is high, the gas must be scrubbed
before discharge to the atmosphere. The scrubber water could be discharged
back to the wastewater treatment plant. Table IV-8 indicates the character-
istics of digested sludge gas. Recovery of the methane off-gas and reuse for
in-plant electrical generation to power motors, pumps, and blowers is
feasible. "Should electric generation be considered, approximately 3.5 cubic
feet of gas is required to produce 1 kilowatt hour (kwh) of electricity"
(Ref. IV-1). Tables IV-9 and IV-10 indicate the qualities of anaerobically
digested sludge.
- 32 -
-------
TABLE IV-6
PROPERTIES OF DIGESTER SUPERNATANT
FROM ANAEROBIC DIGESTION
Item
Standard Rate
High Rate
Temperature, Fahrenheit
Total suspended solids
(mg/1)
Total solids (mg/1)
BOD5 (mg/1)
Volatile solids (mg/1)
Alkalinity (mg/1)
Color (units)
H2S (mg/1)
NH3-Nitrogen
pH (units)
Odor
Digester loading
85-90
4000-5000
2000-3000
2000-3000
650-3000
1000-2400
3000-4000
70-90
240-560
7.0-7.6
Slightly
Offensive
0.15 Ib BOD5/cu ft/day
110-125
10,000-14,000
4000-6000
6000-9000
2400-3800
1900-2700
4900-6700
190-440
560-620
6.4-7.2
Offensive
0.4 Ib BOD5/cu ft/day
Source: Ref. IV-4
Aerobic Digestion
Aerobic digestion taking place in the presence of free oxygen is a
process by which microorganisms oxidize their cell protoplasm and the bio-
logically degradable organic matter in the sludge to carbon dioxide, water,
and ammonia. The ammonia is then converted to nitrates as the aerobic
digestion proceeds. A final material is produced consisting of inorganics
and volatile solids that resist further biological degradation. Aerobic
digestion tanks are not normally covered or heated and are similar to con-
ventional aeration tanks.
The advantages claimed for aerobic versus anaerobic digestion
(Ref. IV-3) are:
(1) volatile solids reductions similar to that obtained
anaerobically;
(2) lower BOD 5 concentrations in the supernatant liquor, generally
around 100 mg/1;
- 33 -
-------
TABLE IV-7
ANAEROBIC DIGESTION-TANK CAPACITY REQUIREMENTS*
Type of Plant
Primary
Primary +
trickling filter
Primary +
activated sludge
Wet Sludge
Dry
solids,
Ib/capita/
day
0.12
0.18
0.19
Percent
solids
5
4
3
cu ft/
capita/
day
0.038
0.072
0.100
Volume Required
34-45 days
detention,
cu ft/
capita
1.3-1.7
2.5-3.2
3.5-4.5
Ten States
Standards,
cu ft/capita
2-3
4-5
4-6
* Based on 0.20 Ib of suspended solids per capita per day in raw sewage.
Note: 1 pound = 454 grams
1 cu ft (cubic foot) = 0.0283 cu m (cubic meter)
Source: Ref. IV-3
(3) production of an odorless, humus-like, biologically stable end
product with excellent dewatering characteristics;
(4) recovery of more of the basic fertilizer value of the sludge;
(5) fewer operational problems; and
(6) lower capital costs.
The major disadvantages are higher power costs associated by supplying the
required oxygen and loss of a useful by-product such as methane (Ref. IV-8).
The use of pure oxygen in a closed-tank system for aerobic digestion
has been investigated (Ref. IV-9). It was noted that much of the heat
generated in the digestion process was retained by the system, resulting in
a significant increase in the sludge temperature and consequently an
increase in the rate of sludge destruction.
Table IV-11 indicates the characteristics of aerobic digestion super-
natants from seven such facilities. The ranges in values are due to the
type of solids-liquid separation processes, digester loading rates, and
- 34 -
-------
TABLE IV-8
CHARACTERISTICS OF SLUDGE GAS
F^OM ANAEROBIC DIGESTION
Con-
stituent
OH,
co2
H2
N2
H2S
Hn (BTU/
° ft3)
dy (air)
Values for Various Plants
42.5
47.7
1.7
8.1
*
459
1.04
61.0
32.8
3.3
2.9
*
667
0.87
62.0
38.0
trace
trace
0.15
660
0.92
Percent
67.0
30.0
*
3.0
* 0.
624
0.86
by Volume
70.0 73.7
30.0 17.7
* 2.1
* 6.5
01-0.02 0.06
728 791
0.85 0.74
75.0
22.0
0.2
2.7
0.1
716
0.78
73-75
21-24
1-2
1-2
1-1.5
739-750
0.70-0.80
* Negligible
Note: d = volumetric density, compared to air
Source: Ref. IV-1
nature of the sludges. Although the aerobic digestion process is relatively
new in terms of its use, a general volume allowance of three to four cubic
feet (8.5 x 10~2 to 11 x 10""^ cubic meters) per capita has been established
as a reasonable design parameter (Ref. IV-1).
Chemical Treatment
Lime has been added to settled sludge in quantities sufficient to
raise the pH to between 11 and 11.5. The lime stabilized sludge dewaters
well on sandbeds without odor problems. The effect of lime addition on the
filterability using vacuum filters has been investigated (Ref. IV-10). The
wastewater treatment plant at Lebanon, Ohio, was being upgraded for phospho-
rus removal by the addition of alum or iron salts. Lime added to the result-
ing sludges stabilized the sludge, produced no obnoxious odors, and increased
the filterability of the sludge by a factor of about two, while cake moisture
remained unchanged.
- 35 -
-------
TABLE IV-9
TYPICAL CHEMICAL COMPOSITION OF RAW AND ANAEROBICALLY DIGESTED SLUDGE
Item
Total dry solids (TS), %
Volatile solids (% of TS)
Grease and fats (ether
soluble, % of TS)
Protein (% of TS)
Nitrogen (N, % of TS)
Phosphorus (P20r, % of TS)
Potash (K20, % of TS)
Cellulose (% of TS)
Iron (not as sulfide)
Silica (Si02, % of TS)
pH
Alkalinity (mg/ liter as
CaC03)
Organic acids (mg/liter
as HAc)
Thermal content (BTU/lb)
(kg cal/g)
Raw Primary Sludge
Range
2.0-7.0
60-80
6.0-30.0
20-30
1.5-4.0
0.8-2.8
0-1.0
8.0-15.0
2.0-4.0
15.0-20.0
5.0-8.0
500-1,500
200-2,000
6,800-10,000
3.7-5.6
Typical
4.0
65
25
2.5
1.6
0.4
10.0
2.5
6.0
600
500
7,600*
4.2*
Digested Sludge
Range
6. 0-12 .,0
30-60
5.0-20.0
15-20
1.6-6.0
1.5-4.0
0.0-3.0
8.0-15.0
3.0-8.0
10.0-20.0
6.5-7.5
2,500-3,500
100-600
2,700-6,800
1.5-3.7
Typical
10.0
40.0
18
3.0
2.5
1.0
10.0
4.0
7.0
3,000
200
4,000**
2.2**
Note: means data not shown in reference cited.
* Based on 65 percent volatile matter.
** Based on 40 percent volatile matter.
Source: Ref. IV-3
- 36 -
-------
o
rH
w
C/)
a
o
CO
a
en
8
O
M
H
O
U
O
13
•H
O
^
1
CO
fi
PM
^
a
O
rl
cd
o
& X-N
CO &••?
cu §
rH -H
,0. CO ,-v
3 co &-a
rH CO-'
O 4J
CO O
PH
O
•H CU
M 13 X-N
O._J Js*>
•ri b^x
ftcS
c
cu
60 O
O *rH x"~s
1-4 4-1 &•«
4J CO — '
•H pi
O
o --
r1-1 X— s
M e^
co ^
CJ
ti
cu
rH 60
Cfl O X-N
4J y i fts?
O 4-1 ^
H -H
rH -H
UH 4-1
C cj
M <:
,
13
S
«t
CU
J_(
O
e
•H
4J
rH
CO
PQ
ro
r-~
o\
CO
1
1
rxs
ON
CM
0
CM
•H
CO
in
vO
CO
m
o
CO
13
0)
4J
CO
CU
60
•H
13
13
CU
•H CU
(H 60
3
4J rH
CO CO
Q)
W
ON CO VO
CM CU 13
C 4J CU
CU CO 4-1
3 > CO
rH -H CU
MH 4-1 60
(3 CJ -H
H < (3
*
*o
C
M
*\
V-4
cu
a,
CO
cO
^
^
ON
o
"*
I
i
ON
iH
in
-*
r^.
•H
CN
oo
CN
o
oo
CO
CO
13
•H
rH
0
CO
4-J
C
cu
3
H
£J
M
.
•a
c
M
M
13
CJ
O
1
O
•H
Pi
t^. ON
co O
rH O
co in
i i
i t
I I
••d" ^sf
VO CO
CO -3"
vO 00
<1" rH
rH rH
-^- vO
CO OO
*3* VO
<• CN
CN -*
O CM
CO CN
CU
60 CU
13 60
3 13
•H 3
CO rH
CO
Tj
CU 13
4-1 CU
CO 4J
> CO
•H CU
4-> 60
O -H
< Q
-3- CM CM
CM OO -3"
00 <1" f^
CM CO CO
1 1 1
1 1 1
1 1 1
rH 00 VO
r~x in in
CM m vo
co r- ro
r^ m in
iH
CM CM rH
vO vO ^1"
vO OO ON
•H 4J
13 4-J CO
CO O CU
*
rH
H
M
M
O
60
CO
CJ
•H
U
O
r^
rC
CM
rH
•
O
vO
ON
CO
1
1
1
1
1
vO
ON
m
CU
60
3
rH
CO
•a
cu
4-1
CO
•H
4J
a
•K
CO
jH
^
0)
V
3
CO
rH
•H
O
oo
CM
-3-
*
,
jg^
*,
M
a)
4-1
ca
cu
CJ
o
02
O
-*
rH
VO
O
*sl"
•
o
rH
CO
CO
1
1
1
1
iH
oo
rH
13
CO Q)
60
r-l 3
CO rH
E CO
•H
(H 13
P. CU
4J
T) CO
CU >
4-J -H
CO 4-1
CU CJ
60 CO
•H
Q
«
H
^
CO
0)
•H
0
CO
01
Q
C
14H
CU
cu
o
M
3
O
oo
- 37 -
-------
TABLE IV-11
CHARACTERISTICS OF AEROBIC DIGESTION SUPERNATANT
FROM SEVEN FACILITIES
Parameter
pH
BOD5
Filtered BOD5
COD
Suspended Solids
Kjeldahl N
Total Phosphorus
Soluble Phosphorus
Average
7.0
______ _______mtt /I _—
500
51
2,600
3,400
170
98
26
Range
5.9-7.7
9-1,700
4-183
288-8,140
46-11,500
10-400
19-241
2.5-64.0
Source: Ref. IV-1
CONDITIONING
Sludge conditioning improves the dewaterability of the sludges by
changing its chemical and physical characteristics.
Chemical Addition
The use of chemicals for sludge conditioning is widely used method
to employ because of the increased yields and greater flexibility obtained
for subsequent sludge treatment and disposal processes. Chemicals such as
ferric chloride, lime, alum, chlorine, and organic polymers are used for
coagulation of the sludge solids and release of bound water. Intimate mix-
ing of the sludge and coagulant is required for proper conditioning, and
the detention times are generally short before the conditioned sludge is
further processed. Flyash from electric power plants or from the incinera-
tion of sludges or solid wastes serves as an excellent sludge conditioner
with the filter press for sludge dewatering. When flyash is not available,
diatomaceous earth may also serve as a sludge conditioner. Table IV-12 is
a listing of chemical dosages for various types of sludges. The specific
resistance is indicative of the dewatering capabilities of sludges; the
- 38 -
-------
TABLE IV-12
DOSAGE OF CHEMICALS FOR VARIOUS TYPES OF SLUDGES
(Conditioners in Percentage of Dry Sludge)
Description
Primary
Primary and
trickling
filter
Primary and
activated
Activated (alone)
Fresh Solids
FeCl3 CaO
1-2 6-8
2-3 6-8
1.5-2.5 7-9
4-6
Digested
FeCl3 GaO
1.5-3.5 6-10
1.5-3.5 6-10
1.5-4 6-12
Elutriated
Digested
FeCl3 CaO
2-4
2-4
2-4
Note: means data not shown in reference cited.
Source: Ref. IV-3
lower the specific resistance, the easier the sludge is to dewater. The
effect of anaerobic digestion as well as various chemical conditioners on
reducing the specific resistance of sludges is siiown in Table IV-13.
Elutriation
Elutriation, which involves mixing of digested sludge with water and
resettling, does not improve the dewatering characteristics of the sludge.
It does, however, reduce the chemical conditioner requirements. The
elutriation process reduces the alkalinity of the sludge, thereby reducing
the amount of ferric chloride required. Carried out in single-stage, multi-
stage (series), or two-stage countercurrent operations, the elutriation
process may use either treatment plant process water or a supplemental water
source of low alkalinity. The elutriation process produces a liquid super-
natant of high suspended solids and BOD5 content which must either be
treated separately or discharged to the head end of the wastewater treatment
plant. Fortunately, the advent of polyelectrolytes has eliminated the need
for elutriation because the flocculating tendencies are not adversely
affected by alkaline sludges (Ref. IV-7).
- 39 -
-------
TABLE IV-13
SPECIFIC RESISTANCE OF SLUDGES
Description
Domestic activated sludge
Activated (digested)
Primary (raw)
Primary (digested)
Primary (digested)
Primary (digested)
Detention Time Stage
7.5 days 1
10.0 days 1
15.0 days 1
20.0 days 1
30.0 days 1
15.0 days 2
20.0 days 2
30.0 days 2
Activated sludge + 13.5% FeCl-j
Activated sludge + 10.0% FeCl3
Activated sludge + 125% (by weight) newsprint
Activated digested sludge + 6% FeCl3 + 10% CaO
Activated digested sludge + 125% newsprint + 5% CaO
Specific
Resistance
(sec^/gram)
x 107
(general values)
2,800
800
1,310-2,110
380-2,170
1,350
1,590
1,540
1,230
530
760
400
400
480
45
75
15
5
4.5
Note: All values were recorded at 500 g/sq cm (grams per square centi-
meter)
Source: Ref. IV-7
Heat Treatment
Heat treatment is a conditioning process involving heating the sludge
for short periods of time under pressure. This heat treatment results in
coagulation of the sludge solids, breakdown of the gel structure of the
sludge, and reduction of the water affinity of the sludge solids. Thus,
the sludge is sterilized, practically deodorized, and readily dewatered
without the addition of conditioning chemicals. The thickened sludge can
- 40 -
-------
be filtered to a solids content of 40 to 50 percent. The supernatant waste
liquor contains high concentrations of short-chain, water-soluble organics
that must be treated either in a separate biological treatment or returned
to the head of the wastewater treatment plant. "It is estimated that direct
recirculation of the undiluted liquors to the treatment plant will result
in a ten percent increase in effluent BODtj and a twenty percent increase in
effluent COD. Such increases are normally undetectable by usual sampling
and analytical methods used in sewage treatment plant control. It is
recommended that, in situations where effluent COD concentration is a
critical water quality criterion, separate biotreatment of the sludge
liquors be employed" (Ref. IV-11). The off-gases produced in this heat
treatment process could be conveyed to either the sludge incinerator or a
separate catalytic combustion unit.
DEWATERING
There are several methods available for dewatering of sludges, namely
the vacuum filter, the centrifuge, the filter press, lagoons, and sand
drying beds. Sludge dewatering processes achieve a degree of moisture
removal intermediate between those of thickening and drying. Dewatered
sludge solids concentrations of 20 to 30 percent are common with organic
solids, and values of 60 percent or more can be achieved with some inorganic
sludges (Ref. IV-12). Table IV-14 indicates the relationship of dewatering
to other sludge treatment processes.
Vacuum Filtration
Vacuum filtration is the most commonly used mechanical dewatering
method in the United States. The solids capture using chemical conditioning
can be very good and a relatively dry filter cake is produced (see Table
IV-15). The filtrate.from a vacuum filter can have suspended solids con-
centrations "varying from 100 to 20,000 mg/1 depending upon the sludge type,
the degree and type of conditioning, the type of filter media, and the
vacuum applied (Ref. IV-4). Discharge of this filtrate back to the main
plant may reduce the plant's overall efficiency, thus necessitating the use
of conditioning chemicals to increase the solids capture. Using these
chemicals makes the vacuum filter a relatively expensive process, and there
have also been problems with blinding of the filter media. "Durable stain-
less steel fabrics and self-cleaning features are improvements that offset
to some degree the high costs of equipment, labor, and chemical conditioners"
(Ref. IV-2). Table IV-15 indicates that it is more advantageous not to
digest mixed sludges prior to vacuum filtration since the chemical require-
ments are higher.
Large vacuum filters are avilable which can continuously dewater up to
100 tons of dry solids per 24 hours with properly conditioned sludges.
However, due to required periodic maintenance, design capacity generally is
kept to 25 to 50 percent of maximum.
- 41 -
-------
w
I
W
Pu
I-H
w
en
to
O
CO
P*
M
U
U
H
O
PM
to
w
to
w
o
o
PS
w
H
cu
CO
U
T3
cu
CU
CO
J5
CU
o
0
CU
co
r-H
M
O
cu
•o
•H
^
O
rl
CM
H
i-H
Cfl
a
o
S3
4J
e
cu
B
4J
CO
CU
rl
4J
CU
V4
PH
0
-, j
•rn
4J
CO
rl
CU
M-J
*rn
o
cj
00
4-* Ci
CO -rl
cu >->
CC rl
n
T)
*"O TO
a cu
CO rJ
rJ P.
C/3
rH
r-H
•H
13
C!
cO
OO
a
•H
qj
O
•H
4J
13
C
O
a
00
P!
•H
a
CU
o
•H
^d
H
13
o
*7^
cu
CO CO
cu cu o
£*"* p>H 53
CO CO
cu cu o
£>H J>H ^3
CO CO CO
CU CU CU
^"* ^ ^
u to
CU CU O
cu
CO CO &
CU (U cfl
cO
cu
I-l
CO CO ,0
(U CU CO
J_!
CO
CU
4J
I-l
•rl
1 ^
3 rH
o a) ts cu
CO 00 O 00
> 3 W 3 s-*
M-( U-l 4J
f>^ -H 13 -H CU
rl rl -H rl r^i
CO 4J rH 4J CO
4J £l O 0(0
O cu co 01 P5
pj 0^ Cjv^
o
o
CO
cu
CO
cu
^
T-l
I-l
CO
3
CO
4J
O
S3
CU
1-1
cO
•rl
J_4
cO
CO
13
cu
M
00
c
•H
^»
M
O
O
S3
O
S3
co
CU
co
cu
o
S3
O
S3
CO
pi
o
O
00
CO
^
CO
cu
?*~*
^
4J rH
O r-l
S3 <0
3
(0
t=>
CU
i-H
ft
CO
•rl
rl
CO
CO
CU
CO
CU
CO
cu
CO
CU
CO
CO
cu
^
PH
J_J
cu
4-1
rH
•H
Pn
4-1
l-l
m
rH
CO
4-1
a
o
N
•H
rl
o
w
Cfl
CU
^~*
CO
cu
CO
CU
CO
cu
CO
CU
K*
CO
CU
CO
rl
CU
4J
r- (
•H
^
I
>
cu
o
M
o
to
- 42 -
-------
TABLE IV-15
TYPICAL ROTARY VACUUM FILTER RESULTS FOR SLUDGE
CONDITIONED WITH INORGANIC CHEMICALS
Type Sludge
Raw Primary
Anaerobically Digested
Primary
Primary + Humus
Primary + Air Activated
Primary + Oxygen
Activated
Digested Primary and
Air Activated
Chemical Dose (Ib/ton)
Ferric Chloride
1-2
1-3
1-2
2-4
2-3
4-6
Lime
6-8
6-10
6-8
7-10
6-8
6-19
Yield
(Ib/hr/fO
6-8
5-8
4-6
4-5
5-6
4-5
Cake
Solids (%)
25-38
25-32
20-30
16-25
20-28
14-22
Note: lb/hr/ft2 x 4.89 = kg/hr/m2
Source: Ref. IV-1
Centrifugation
Centrifuges have also been used as a dewatering method as well as a
thickening method. It can produce dewatered cakes generally comparable to
those obtained by vacuum filtration (see Table IV-16). Centrifugation has
several advantages over vacuum filtration; namely, it is simple, compact,
totally enclosed (thereby reducing odor problems in the solids handling
facilities), and normally used without chemical aids (Ref. IV-5). As
with the vacuum filter, the centrate may have a high suspended solids con-
tent, which, if recycled back to the main treatment plant, may reduce the
overall plant efficiency. If this were the case, conditioning chemicals
may be required.
Basket centrifuges have been used principally in dewatering sludges in
small wastewater treatment plants. The unit is a batch device with alter-
nate charging of feed sludge and discharging of dewatered sludge cake.
- 43 -
-------
TABLE IV-16
RESULTS OF CENTRIFUGATION OF SLUDGES
USING A SCROLL-TYPE CENTRIFUGE
Type of Sludge
Raw primary
Digested primary
Activated
Raw primary and activated
Digested raw and activated
Cake
concentration
(% solids)
28-35
25-35
6-10a
18-24
18-24
Solids
without
chemicals
85-90
80-90
50-80
50-70
recovery (%)
with
chemicals
>95
>95
>95
>95
a
Without chemicals
Source: Ref. IV-12
Sand Drying Beds
Sand drying beds are used to dewater digested sludge. Using drying
beds for dewatering raw sewage is not practiced because raw sludge is
odorous, it attracts insects, it does not dry satisfactorily when applied
at reasonable depths, and the oil and grease discharged with the slimy raw
sludge clog the sand bed pores and thereby seriously retard drainage
(Ref. IV-5). Covered beds using greenhouse-type enclosures are used where
it is necessary to dewater continuously throughout the year regardless of
weather. These enclosures protect the drying sludge from rain, control
odor and insects, and reduce the area required for drying by approximately
70 percent (Ref. IV-1).
The sludge dewaters by drainage through the sludge mass and supporting
sand and by evaporation from the surface exposed to the air. Most of the
water does leave by drainage; therefore, an adequate underdrain system is
essential. The water collected in the underdrain system is generally dis-
charged back to the head end of the treatment plant. The dried sludge
moisture content is approximately 60 percent after 10 to 15 days under
faborable conditions.
Table IV-17 indicates the criteria for the design of sandbeds, while
Table IV-18 indicates the quality of the digested cake.
- 44 -
-------
TABLE IV-17
CRITERIA FOR THE DESIGN OF SANDBEDS
Type of Digested Sludge
Primary
Primary and standard trickling filter
Primary and activated
Chemically precipitated
Area
(sq ft/capita)
1.0
1.6
3.0
2.0
Sludge Loading
Dry Solids
(Ib/sq ft/yr)
27.5
22.0
15.0
22.0
Note: sq ft x 0.0929 = sq m
Ib/sq ft/yr x 4.89 = kg/sq m/yr
Source: Ref. IV-1
Lagoons
Lagoons for sludge dewatering have been commonly used in the United
States, primarily because of land availability, ease of operation, and low
cost. Sludge is periodically removed and the lagoon is refilled. Prior to
filling, the sludge must be stabilized to prevent odor problems.
Recommendations for required area vary from one square foot per capita
(9.3 x 10~2 square meters) for primary digested sludge in arid climates to
three to four square feet (28 x 10~2 to 37 x 10 square meters) per capita
for activated sludge plants in areas where the annual rainfall is 36 inches
(Ref. IV-1). Other design considerations include groundwater protection,
climate, subsoil permeability, and lagoon depth. Sludge may be dewatered
from five percent solids to 40 to 45 percent solids in two to three years
using sludge depths of from two to four feet (0.61 to 1.22 meters) (Ref. IV-1)
Pressure Filtration
Sludge dewatering by means of a filter press is a batch operation.
Filter plates are usually precoated with either diatomaceous earth or flyash
slurry, which reduces filter blinding and provides easy separation of the
sludge cake from the filter media, usually monofilament filter cloth. Sludge
is pumped into the press, and passes through feed holes along the length of
the filter. As the press is closed by either electrical or hydraulic means,
- 45 -
-------
TABLE IV-18
AIR-DRIED DIGESTED PRIMARY SLUDGE CAKE
Quality
Characteristics
Physical texture
Color
Odor
Solids content
Volume
Volatile matter content
PH
Carbon, total
Nitrogen, total
Phosphorus, total
Granular friable lumps, about pea size if
ground.
Black or dark brown
Earthy
About 40% total solids
25% to 50% of wet sludge applied,,
Average range 40 to 55% of the total solids.
6.0 to 6.5 after storage
28% of dry weight
2.3% of dry weight
0.85% of dry weight
Note: The values for carbon, nitrogen, and phosphorus represent the
average of 15 digested primary sludges collected at sewage treat-
ment plants in Connecticut and tested by the Connecticut Agri-
cultural Experiment Station.
Source: Ref. IV-7
water is pressed out of the feed sludge and is discharged through filtrate
drain holes. When the filtrate flow is essentially completed, the press is
opened and the dried cake is discharged to conveyors or cake hoppers, and
the cycle is then repeated. Advantages and disadvantages of pressure
filtration are noted in Table IV-19.
The necessity of adding conditioning chemicals to the sludge prior to
pressing increases the operating costs and the quantities of sludge to be
disposed, "Lime and ferric chloride may add 25 percent by weight of dry
solids while preconditioning with ash may add 200 percent of dry solids
weight to the sludge" (Ref. IV-2). Heat conditioning may eliminate the
need for chemical conditioning; however, difficulties have been noted with
sludge cake discharge and high levels of suspended solids in the filtrate
(Ref. IV-2). Incineration of the sludge cake can produce a flyash useful
in conditioning the sludge applied to the filter press. Typical filter
press production data is given in Table IV-20.
- 46 -
-------
TABLE IV-19
PRESSURE FILTRATION CONSIDERATIONS
Advantages
Disadvantages
Higher cake solids concentrations
(30 to 50 percent)
Improved filtrate clarity
Improved solids capture
Reduced chemical consumption
Batch operation
High labor costs
Filter cloth life limitations
Operator incompatibility
Cake delumping
Source: Ref. IV-1
SLUDGE DRYING AND REDUCTION
Sludge reduction processes are generally thermal processes and are
intended to reduce the solids required for final disposal or to recover a
resource. Table IV-21 indicates the sludge reduction and resource recovery
processes discussed in the subsequent sections and in Chapter VI.
Incineration
Combustion by incineration serves as a means of* reducing total sludge
volume. Because few sludges have a volatile solids content as high as
70 percent, a significant amount of ash will remain after, burning. Undi-
gested sludge has a higher heat value than digested sludge, making undigested
sludge easier to combust. For sludges with low heat values, supplemental
fuel may be added. End products of combustion are usually water, carbon
dioxide, sulfur dioxide, and inert ash (Ref. IV-5). The primary methods of
incineration are the multiple hearth furnace and the fluidized bed reactor
incinerator.
A complete discussion of incineration, particularly in light of
resource recovery and reuse, is presented in Chapter VI.
Wet Air Oxidation
Wet air oxidation involves burning of organic matter in the absence of
flame and in the presence of liquid water. Temperatures and pressures on
the order of 400 to 600 F (150 to 225 C) and 1200 to 1800-psig [pounds per
square inch gauge (8.45 x 105 to 12.6 x 105 kg/sqm)] are used for complete
- 47 -
-------
TABLE IV-20
TYPICAL FILTER PRESS PRODUCTION DATA
Sludge Type
Raw Primary
Raw Primary
with less than
50% EAS
Raw Primary
with more than
50% EAS
Digested and
Digested with
less than 50%
EAS
Digested with
more than
50% EAS
EAS
Suspended Solids
(%)
5-10
3-6
1-4
6-10
2-6
Up to 5
Conditioning of
Dry Solids (%)
Ash 100
FeCl3 5
Lime 10
Ash 150
FeCl3 5
Lime 10
Ash 200
FeCl3 6
Lime 12
Ash 100
FeCl3 5
Lime 10
Ash 200
FeCl3 7.5
Lime 15
Ash 250
FeCl3 7.5
Lime 15
Cake Solids
(%)
50
45
50
45
50
45
50
45
50
45
50
45
Time Cycle
(hr)
1.5
2.0
2.0
2.5
2.0
2.5
1.5
2.0
1.5
2.5
2.0
2.5
Note: EAS = Excess Activated Sludge
Source: Ref. IV-1
- 48 -
-------
TABLE IV-21
REDUCTION PROCESSES
Reduction Process
Pretreatment Required
Additional Processing
Requirements
Established Processes
Incineration
Wet Air Oxidation
Heat Drying
Experimental Processes
Pyrolysis
Incineration/
Chemical Recovery
Thickening and Dewatering
Thickening
Thickening and Dewatering
Thickening
Thickening and Dewatering
Landfill ash
Treat cooking liquor,
landfill ash
Use dried sludge as
soil conditioner
Utilize by-products
of gas, carbon ,
steam. Dispose of
residue
Landfill ash.
Recover lime from
recalcination or
heat in power
boilers
Source: Ref. IV-1
oxidation of organics (Ref. IV-12). Because it is not necessary to supply
energy for the latent heat of vaporization of water, wet air oxidation is
particularly applicable for materials like organic sludges which are com-
bustible but cannot be readily separated from water. The problem of ash
disposal in the wet oxidation process is somewhat different than in incinera-
tion because the ash is conveyed in a significant volume of water. Signi-
ficant concentrations of nutrients and soluble organic material are contained
in the waste liquid portion of the process and should be recycled to the
treatment plant or treated in a separate facility. Direct recirculation of
untreated liquors to the wastewater treatment plant is estimated to cause a
10-percent increase in the effluent BOD^ and 20-percent increase in the
effluent COD, assuming the capacity is available in the main plant to handle
the recycled load (Ref. IV-11). Table IV-22 indicates several values obtained
from a pilot scale operation on the liquid effluent, and Table IV-23 indicates
an analysis of the ash from the process.
- 49 -
-------
TABLE IV-22
WET-AIR OXIDATION PROCESS EFFLUENT
Volatile
Solids
Concen-
tration
Range
(Percent)
2.00-2.99
3.00-3.99
4.00-4.99
Reactor Effluent
NH--N
(rag/1)
1,370
1,625
1,640
Organic
N
(mg/D
368
425
548
Volatile
Acids
as acetic
(mg/1)
3,200
3,480
3,980
COD
(mg/1)
10,200
13,200
16,600
Settled
Effluent
COD
(mg/1)
8 , 300
9,800
11,600
Source: Ref. IV-5
TABLE IV-23
TYPICAL ANALYSIS OF ASH FROM WET OXIDATION PROCESS
Parameters
Iron (Fe)
Silicon (Si)
Potassium (K)
Manganese (Mn)
Calcium (Ca)
Aluminum (Al)
Zinc (Zn)
Copper (Cu)
Magnesium (Mg)
Phosphorus (P)
Boron (B)
Nickel (Ni)
Sodium (Na)
Specific gravity
Percent*
4.92
3.78
0.76
0.025
0.87
3.90
0.04
0.24
0.03
2.62
0.03
0.01
0.12
2.23
* Metals determined spectrometrically, percent by weight.
Source: Ref. IV-5
- 50 -
-------
Difficulties with the system include the high organic load exerted by
the reactor effluent on the wastewater treatment plant, severe corrosion
problems in the oxidation chamber and heat exchanger surfaces requiring
frequent maintenance, and accidents with high-pressure steam lines.
Heat Drying
Heat (flash) drying is the instantaneous removal of moisture from
sludge solids by introducing them into a hot gas stream.
Wet sludge from a dewatering process is introduced into the dryer with
some previously dried sludge and hot gases from the furnace. Drying is
essentially completed with the sludge now approximately at 8- to 10-percent
moisture. Dried sludge is separated from the spent gases in a cyclone and
either sent to fertilizer storage or to the furnace for incineration.
Primary combustion air is preheated in the deodorized gas heat exchanger
and introduced into the furnace as combustion of fuel such as gas, oil, coal,
or wastewater sludge occurs. Ash accumulates in the furnace bottom and must
be periodically removed either by sluicing to an ash lagoon, to a landfill,
or to an ash utilization process such as vacuum or filter press operations.
Effluent gases passing through the furnace and combustion air preheater
then pass through a dust collector and an induced draft fan to a discharge
stack.
Further information on heat drying may be found in Chapter VI.
Pyrolysis
Pyrolysis is the destructive distillation of refuse, sewage sludge, or
other organic materials under pressure and heat in the absence of oxygen.
Most of the combustion process is carried out within a closed reactor
chamber, normally at temperatures lower than in incinerators.
The pyrolysis process has been used on a very limited basis and pri-
marily on municipal refuse rather than sewage sludges. Where municipal
refuse has been pyrolized, the products have been gases, pyroligneous acids
and tars, and char. The gases consist mainly of hydrogen, methane, carbon
monoxide, carbon dioxide, ethane, and ethylene. The pyrolysis of digested
sewage sludge yields the same products as those from the solid waste,
although the char shows about 70 to 75 percent lower BTU content (Ref. IV-13).
Further information on pyrolysis, the process and its potential for
resource recovery, may be found in Chapter VI.
Lime Recalcination
Lime is often used in wastewater treatment as a coagulant for
phosphorus removal.- It can be applied either as a tertiary step or ahead
- 51 -
-------
of the primary clarifiers in either a biological or physical-chemical
wastewater treatment plant.
The process of recalcining involves heating the dewatered sludge con-
taining calcium driving off the water and carbon dioxide and leaving the
calcium oxide (quicklime). When coagulating raw wastewaters, the inert
solid fraction can be removed before recalcination by centrifugation. This
inert solid removal must occur to prevent solids buildup within the waste-
water treatment process.
Further information on lime recalcination as a resource recovery process
may be found in Chapter VI.
PERFORMANCE
A variety of sludge handling and treatment systems have been described,
primarily from the viewpoint of presenting information useful in the 208
planning process. System advantages and disadvantages were noted, process
sidestreams were discussed in light of their environmental and system upset
potential, and possibilities of resource recovery and reuse were presented.
Table IV-24 indicates the normal quantities of sludge produced by
different treatment processes. Table 1V-25 indicates the sludge processing
unit performances where data is available in terms of total solids content
of the influent and effluent streams, volume reduction, and solids recovery.
The utility of these two tables is in determining the amount of solids to be
handled in various sludge treatment processes such that the cost information
to follow may be used to obtain first-order cost estimates for planning
sludge treatment alternatives. For ease of use, the values in Table IV-24
are given both in pounds of dry solids per million gallons of wastewater and
pounds of dry solids per 1000 persons.
ECONOMICS
The unit processes discussed previously for sludge handling and treat-
ment are each characterized by a unique performance under specific influent
conditions and effluent requirements. The use of a particular unit process,
e.g., centrifugation, in different locations within the treatment train
(thickening versus dewatering) or with different types of sludges will
result in different equipment and operating requirements. Therefore, the
capital and operating costs may vary substantially with the type of applica-
tion. However, experience gained over time has narrowed down the possible
physical arrangements to those more efficient in performance or economical
in cost. For example, it is usually impractical both from an operating as
well as economic viewpoint to digest sludges before incineration, due pri-
marily to the loss of organic fuel value in the digesting process. It then
requires supplemental fuel which costs money to incinerate the digested
sludge.
- 52 -
-------
to
•o
rH
0
to
X
Q
II)
o c >>
--. O O rH
rj * ^ (V
rH Ol TJ
(X
c:
O »M 41
--. -H O 00
.0 T-H to
r-) rH rH 3
E DO 10
IM
U O
•H 0)
UH >N DO
•rl U TJ
O -H 3
41 > rH
CX CO tO
in rl
DO
VtH
O O
•rt 41 t/}
IM >N DOTJ
•H 4-1 TJ iH
O -rl 3 rH
41 > rH 0
CX CO 10 10
CO rl
DO
41
rl
3
m t~e
•rl
O
X
41
DO
TJ
3
rH
to
I*-.
=
^
4J
•H
4J
c
CO
3
^
rH
rt
E
o
z
n
--.OCX
U O O rH
IM O tO iH
« ij O
3 i-H 41 TJ
u rx
c
~~^ O U-l 4)
10 -H O DO
C rH CO
O rH i-H 3
fr-l TH a 41
E DO <0
C
O NM OJ
--. -rl O 00
rH rH CO
O rH rH 3
CJ i-l CO 4>
' E DO tO
B
to
U
0
(X,
4J
c
01
g
0)
41
^4
H
in in in
CNI r-- r*-
O O O
in in in
CM r- r-
rH
CM CO
0 O I
. • 1
rH rH 1
O
•3- 1 1
• I I
rH 1 1
in *3 o
ON ON NO
o o r-
ON ON-U-I
CO rH
in -3"
m CM ON
CM NO O
0 O
in in 1
ON VT 1
• • 1
CM rH
•O
C
10
0)
.* C
C O
CO
4J TJ
41
0) w
4-1 41
C 10 u
•rl CJ 3
4-1 CX 01
tO 41 TJ
4J (0
c -a
41 C C
E T) vH CO
•rl 4>
41 tO 4> 41 tO
0) CD *_» 4-1 TJ
DO tO tO 41
X -H •« OJ .0
IJ TJ DO DO
CO C iH -rl
B p> o a
•rl
(4
*
m
f-^.
o
m
r»»
o
0
tH
1
I
I
tn
CJ
ft
^
*O
C1
i-H
|
i
c
o
TJ
4)
H
41
4-1
CO 10
3 ^
41 41
TJ 4J
rH
•a IH
a
B
•O 3
iJ 0
f> to
41 >
DO
iH
O
CO
sj
NO
-3
m
CM
o
r*t
CO
CO
i«4
in
CM
ON
ON
ON
r-
rH
CO
in
•or
^
L^
41
4J
•rl
UH
DO
C
•rl
rH
^
U
iH
rl
H
O O
CO CO
Co CO
O 0
0 0
CO CO
CO
O 1
. 1
r-l 1
CO
ON 1
. 1
rH 1
in m
CM CM
ON r-
m co
CO ON
NO rH
0 0
CM NO
CM
O
CM 1
rH i
• 1
m
a
01
u
rH
•rl
UH
C E
o S
•rl 3
4J O
to to
•H
CX C
•n o
o
4) "O
U 41
CX ^
rH 4->
n n
0 3
IH 01
E 0
41
JZ
0
•a
c
10
d
o
•H
4J
to
c
tu
E
•H
•a
tu
to
l-i
R)
E
v(
U
(X,
•3 -^
CO CO
CM CM
O O
*3 *J
CO CO
CM CM
CM m
O ON
rH O
1 1
1 1
i 1
NO O
ON CO
0 0
CM O
CO iH
2 TJ TJ *"
CO 4) 41 E
> 4J 4J 3
•rl 0) 10 3
^1 O 41 U
O DO DC tO
0) -rl iH >
•O TJ
B B
O O
*3 *3
rH rH
O O
o o
-3 TJ
0>
0) rl
-rl
C «H
CO
e
TJ 3
41 -3
4J U
to CO
01 >
CO
•H
Q
in m in
CM CM CM
CM CM CM
O O O
in m in
CM CM CM
CM CM CM
in
o m in
O ON CM
rH O rH
m
CM 1 1
• i 1
r-l 1 1
m
CO O -3
ON CO
O O O
CO ON CO
in rH
CM
CM f^
O NO i-H
m m rH
f>h
o
0 I 1
3 X
0 ti
tO TJ
4) 4J
DO £ to
TJ O 41
3 01 JZ
rH DO T>
10 TJ 41 >N
3 U .0
TJ rH 41
41 tO 4J TJ
4-1 tO 41
CO 4J 3 -rl
^ 41 41 VJ
•H 3 Q Q
U
-*
rH ON
CO NO
O O
rH ON
CO NO
*3 *3
O O
rH rH
O r^
-» CM
• •
rH rH
o m
ON CO
O r»
CM NO
rH
I 1
i 1
1 1
O 0
o o
ON W|
TJ TJ
41 41
4J 4-1
to to
41 4)
DO DO
•rl -H
TJ TJ
m m
C C
CO to
4J 4J
O 14H
•H tu
4J O
CX .C
41 • 8
in M
41
DO
10
3
41
0)
C
v4
to
TJ
•rl
rH
O
O
T>
4>
p;
41
rx
0)
3
to
iw
o
•»
X
rH
^H
TJ
0
•rl
(X
U
rl
41
rx
.0
rH
m
CM
•
0
rl
0
•>
P.
O
o
CO
TJ
tf
TJ
U
DO
O
0
rH
IM
O
3
o
rH
IM
41
DO
to
3
01
CO
a)
C
O
TJ
41
0)
CO
Ss
rH
•rl
a
TJ
Q ^%
C rH
0 iH
10 OS
\4 TJ
OJ
rx a
c
0 0
o u
0 rl
rH 01
%">* P^
g
^5
U 0
CO --
CO DO
CM
O -3
• m
O «J
1 1
IX
rH
tO >N
•0 rH
•rl
10 0
O ""
tO 0)
rl d
01 O
(X 10
rl
O 41
0 fX
0
rH O
*•. O
u o
UH rH
^^.
3 f>
U rH
B 8
3
3 fl 3
U O
O
O O O
0 O 0
0 rH 0
rH —** rH
-•x DO--.
rl A! DO
01
4J O O
•H ^ CM
rH CM rH
III
rH rH
HJ CO rH
DO DO CO
DO
C C
O O C
TH iH O
rH rH iH
rH rH rH
11^
rH C ~-
tO O f
DO 4J rH
• i
01
4J
O
f^.
1
M
U4
01
a:
• •
01
u
IH
3
O
- 53 -
-------
TABLE IV-25
SLUDGE PROCESSING UNIT PERFORMANCE
Process
Thickening
Gravity
Flotation
Treatment
Aerobic
digestion
Anaerobic
digestion
Incineration
Wet oxidation
Heat
Lime stabili-
zation
Dewatering
Drying beds
Vacuum filter
Pressure fil-
tration
Centrifuge
Heat drying
Feed
Primary
WAS
Primary & WAS
Digested primary
Digested primary
i WAS
Primary & WAS
WAS with chem.
WAS without chem.
Primary, thickened
Primary & WAS,
thickened
Primary, thickened
Primary (, WAS,
thickened
Primary, dewatered
Primary & WAS,
dewatered
Primary or primary
& WAS
Any, thickened
Primary, thickened
Primary & WAS,
thickened
Any, digested
Any, lime stabiliza-
tion
Primary, conditioned
Primary 6 WAS, con-
ditioned
Digested, conditioned
Digested, conditioned
Digested
Digested, conditioned
Digested
Total
solids in
percent
1-3
0.5-1
2
2-5
2-3
2
0.5-1.5
0.5-1.5
5-8
4-5
5-8
4-5
25
25
4-8
4-8
5-8
4-5
2-5
4-8
2-3
2-3
2-5
5-6
2-5
2-5
2-5
Total
solids out
weight
5-8
2-3.5
4-5
5-8
5-7
4-5
3.5
3-5
2-4
2-5
2-3
100
100
4-8
4-8
5-8
4-5
40
40
35
25
25-37
30-40
18-21
20-25
90
Volume
reduction
Solids
recovery
percent
50-60
50-60
50-60
50-60
65
65
60
10
10
0
0
75-85
75-85
0
0
0
0
50
50
90
85-90
90
80-90
60-75
75-85
95+
98+
98+
98+
98+
98+
95+
95+
95+
60-65
50-60
40-60
50-60
30-40
30-40
98+
98+
110
110
98+
98+
90+
90+
90-95+
98+
55
90-95
98+
Note: WAS «• Waste Activated Sludge, same as Excess Activated Sludge (EAS)
Source: Ref. IV-2
- 54 -
-------
The following capital costs were developed from studies by others
(Refs. IV-1, IV-2, IV-5, IV-6, 1V-7, IV-8, IV-13, IV-14, IV-15, IV-16, and
IV-17) having experience with recently constructed facilities, manufacturers'
quotes, and other technical literature.
Capital Costs
Capital costs for unit processes are referenced to an Engineering News
Record (ENR) Construction Cost Index of 2200, representing mid-1975 costs.
The unit prices include basic manufacturing and installation costs, con-
tractor's profit, and a 25-percent allowance for engineering, legal costs,
and contingencies. Not included in the prices are the costs of land or the
acquisition of rights-of-way.
The following process descriptions and assumptions are used in this
report to develop the capital cost curves in Figure IV-1 (Ref. IV-2).
Gravity Thickening
The costs for gravity thickening include thickening tanks and ancil-
lary mechanical and electrical equipment. The design factors are a minimum
detention of six hours with a 20 m3/(m)2(day) [500 gal/(ft)2(day)] overflow
rate.
Dissolved Air Flotation
The air flotation thickening cost curve includes the flotation tank,
sludge removal equipment, pressurization system, discharge piping and all
other related mechanical and electrical equipment. The air flotation
system is sized for a solids loading of 98 kg/m3 [20 Ib DS/(ft)2(day)].
Aerobic Digestion
The aerobic digestion process costs include an aeration tank,
mechanical aerators-mixers, piping and valves, ladders and rails, pumping
equipment and installation for the transfer of sludge from the thickener.
The aerobic digester is sized for a sludge retention period of 15 days,
with approximately a six-percent solids content in the liquor.
Anaerobic Digestion
Anaerobic digestion process costs are based upon an assumed solids
loading of 3.2 kg/m3 [0.2 lb/(ft)3(day)]. Costs included in anaerobic
digestion are for the digester, floating covers, gas mixing equipment,
heat exchangers, gas collection equipment, control building, piping to an
on-site location and associated mechanical and electrical equipment.
- 55 -
-------
Inc in era t i on
In addition to the incinerator, incinerator building, sludge conveyor
and ash handling equipment, the capital costs of incineration include flue
gas scrubbing facilities. Incineration costs are based upon a feed sludge
with 25-percent dry solids and a multiple-hearth type of incinerator. The
fluidized bed incinerator costs include sand costs.
Heat Treatment
The costs of heat treatment are based upon the installation of a
Zimpro unit and include a complete oxidation unit, installation, building
and foundation and piping for the removal of effluent. The equipment is
sized to treat a three-percent solids content sludge with a continuous
24-hour-per-day operation, allowing for a 20-percent down time for main-
tenance.
Lime Treatment
Chemical stabilization by lime of sludges includes a mixing-thickening
tank, a chemical storage tank, air mixer, and chemical feeding equipment.
The costs of chemicals are included with the annual operating costs. The
chemical treatment system is based upon a lime dosage of 0.1 kg/kg dry
sludge solids.
Sand Drying Beds
Installation costs and beds for drying sludges include normal excava-
tion, piping for sludge distribution, sand and gravel drainage beds, and an
underdrain system. Mechanical sludge loading equipment and covers for the
sand beds are not included. A sludge loading of 0.24 kg/(m) (day) [.05 Ib
dry solids/(ft) (day)] is assumed.
Cent rifug at ion
Thickening of sludges with centrifuges requires installation of cen-
trifuges, conveyors, platform and sludge hopper and building. The centri-
fuge, a solid-bowl horizontal type, is assumed to be operated 16 hours per
day, seven days per week, with digested primary and secondary sludge.
Vacuum Filtration
Vacuum filtration costs include either a continuous belt or drum-type
vacuum filter, housing, pumps, equipment for chemical conditioning and
biological treatment of the effluent. The vacuum filters are loaded at the
rate of 49 kg/(m)2(hr) [10 Ibs DS/(ft)2(hr)].
Pressure Filtration
The dewatering of sludge by pressure filtration involves capital cost
items which include vertical plate pressure filters, sludge chemical
- 56 -
-------
pretreatment facilities, precoating equipment for the filter plates, pumps,
conveyors and controls, and installation within a building.
Operation and Maintenance Costs
The operation and maintenance costs for the unit processes have been
related to the average daily weight of dry solids processed and are shown
in Figure IV-2. Operating labor is used for equipment start-up, sampling
analyses, monitoring, control, and shutdown. Maintenance labor is required
for cleaning and repair of process equipment.
Materials incorporated in the costs include expendable materials,
chemicals, power for pump and blowers, and replacement sand for sand beds,
and fluid bed incinerators. Included in these costs are credit for
recovered and recycled energy in direct heat exchange during incineration
and indirect internal energy reuse such as recovery of heat from digester
off-gas systems.
Labor costs were based on an average hourly wage rate of $4.00 with
25-percent additional fringe benefits. Costs of materials were adjusted to
a Wholesale Price Index for Industrial Commodities of 150.
It should be noted that both the capital and operation and maintenance
cost curves as presented represent average costs for these solids handling
facilities. Care should be exercised in their use, particularly in extra-
polation at the low end. Where local cost data is available to the 208
planning agency, it should be used either in lieu of these curves or as
verification of their applicability and accuracy.
- 57 -
-------
-------
FIGURE I3Z-I
CAPITAL COSTS FOR SOLIDS PROCESSING FACILITIES
100
80
60
50
40
30
20
£ 10
o
8
7
6
° 5
o
•o
c
o
CO
o
o
•z.
o
H
o
3
DC
Z
O
o
1.0
.8
.6
.5
.4
.3
.2
GT
AF
DAe
DAn
VF
PF
I (I I I I I
LEGEND
Grovity Thickening
Air Floatation
Digestion, Aerobic
Digestion, Anaerobic
Vacuum Filtration
Pressure Filtration
I I I I I I I
I I I I I I I I
1 I I I I I I
10 20 30 50 70 100 200 500 1000
DRY SOLIDS PROCESSED, thousand pounds per day
2000
I I I I I I
I
_L
I I I I I I I
I
I
I I I I I I
5 6 7 8 10 20 30 50 100 200
DRY SOLIDS PROCESSED, metric tons per day
500
900
- 58a -
-------
FIGURE IE-I Con't
CAPITAL COSTS FOR SOLIDS PROCESSING FACILITIES
100
80
60
50
40
30
20
10
8
7
6
5
4
3
z
o
o i.o
£ -8
o
•o
C
o
z
o
o
.6
.5
.4
.3
i
HT
CT
C
SB
FB
I I I I I I I
LEGEND
Incineration
Heat Treatment
Chemical Treatment
Centrifugation
Sand Bed Dewatering
Fluid Bed Incineration
I I I I I I I
I
I I I I l I I I
I
J _ I
I I I l
10 20 30 50 70 100 200 500 1000
DRY SOLIDS PROCESSED, thousand pounds per day
2000
I I l I l I
I
I
1 I l l l I I
l
I
l I I I I
5 6 7 8 10 20 30 50 IOO 2OO
DRY SOLIDS PROCESSED, metric tons per day
500
900
- 58b -
-------
FIGURE IE-2
ANNUAL OPERATION AND MAINTENANCE COSTS
FOR SOLIDS PROCESSING FACILITIES
10000
8000 -
III
I I I I I I I
Gravity Thickening
Air Flotation
DAe Digestion, Aerobic
DAn Digestion, Anaerobic
Vacuum Filtration
Pressure Filtration
I I I I II
10 20 30 50 70 100 200 500 1000
DRY SOLIDS PROCESSED, thousand pounds per day
2000
I I I I I I
I
I
I I I l I I I
_L
I
i l l I I I
5 6 7 8 10 20 30 50 100 200
DRY SOLIDS PROCESSED, metric tons per day
500
900
-59a-
-------
FIGURE ISC- 2 Cent.
10000
8000
6000
5000
4000
3OOO
2000
o
w
>«IOOO
soo
600
50°
400
•o 300
c
o
in
o 200
O 100
o
80
O
| so
< 50
CE
UJ 40
a.
° 30
20
ANNUAL OPERATION AND MAINTENANCE COSTS
FOR SOLIDS PROCESSING FACILITIES
10
i
HT
CT
C
SB
FB
[ I I 7 I I I
LEGEND
Incineration
Heat Treatment
Chemical Treatment
Centrifugation
Sand Bed Dewatering
Fluid Bed Incineration
I I I I I I I
I I I I I I I 1
I
I II I I I I I
10 20 30 50 70 100 200 500 1000
DRY SOLIDS PROCESSED, thousand pounds per day
2000
I I I I I I
I
I I I I I I I
J_
_L
j I I I I 1
5 6 7 8 10 20 30 50 100 200
DRY SOLIDS PROCESSED, metric tons per day
500
900
- 59b -
-------
CHAPTER IV
REFERENCES
IV-1 Sludge Treatment and Disposal, Process Design Manual, U. S.
Environmental Protection Agency (October 1974).
IV-2 Analysis of the 1973 Sewage Sludge Disposal Problem in Southern
California, Bursztynsky, T. A., Davis, J. A., Feuerstein, D. L.,
Doyle, A. A., and MacLaren, F., prepared for the Implementation
Research Division, U. S. Environmental Protection Agency, by
Engineering-Science, Inc. and J. B. Gilbert and Associates (draft
June 1974).
IV-3 Wastewater Engineering^ Metcalf & Eddy, Inc., McGraw-Hill Book
Co., New York, New York (1972).
IV-4 "Treatment of Supernatants and Liquids Associated with Sludge
Treatment," Molina, J. F., Jr., and DiFilippo, J., Water and
Uagte Engineering (1971).
IV-5 A Study of Sludge Handling and Disposal, Burd, R. S., publication
WP-20-4, U. S. Department of the Interior, FWPCA (May 1968).
IV-6 "Summary Report: Pilot Plant Studies on Dewatering Primary
Digested Sludge," Parkhurst, J. D., et_ al, report for EPA
Contract No. R801658 (1972).
IV-7 Planning and Technical Considerations for Ultimate Disposal of
Residual Wast e s, Wyatt, J. W., prepared for the Office of Research
and Monitoring, U. S. Environmental Protection Agency, Contract
No. 68-01-2222 by Engineering-Science, Inc. (August 1974).
IV-8 "Aerobic Digestion of Activated Sludge to Reduce Sludge Handling
Costs," Cameron, J. W., presented at the 45th Annual Conference
of the Water Pollution Control Federation, Atlanta, Georgia
(October 1972).
IV-9 "High Purity Oxygen Aerobic Digestion Experiences at Speedway,
Indiana," Gay, D. W., Drnevich, R. F., Breider, E. J., and Young,
K. W., Municipal Sludge Management - Proceedings of the National
Conference on Municipal Sludge Management, Pittsburgh, Pa. (June
1974).
IV-10 "Lime Stabilization of Primary Sludges," Farrell, J. B., Smith,
J. E., Jr., Hathaway, S. W., and Dean, R. B., Journal of the Water
Pollution Control Federation, 46, 113 (1974).
IV-11 "Biological Treatment of Thermally Conditioned Sludge Liquors,"
Erickson, A. H., and Knapp, P. U., Zimpro, Rothschild, Wisconsin
(December 1969).
- 60 -
-------
-------
CHAPTER IV
REFERENCES
(Continued)
IV-12 Physicochemical Processes for Water Quality Control, Weber, W. J.,
Jr., Wiley-Interscience, New York (1972).
IV-13 "Sludge Handling and Disposal, Phase I - State of the Art,"
prepared for the Metropolitan Sewer Board - Twin Cities Area,
St. Paul, Minn., by Stanley Consultants, Inc. (November 1972).
IV-14 "Sludge is Beautiful in the Twin Cities," Storck, W. J., Water
and Wastes Engineering (July 1974).
IV-15 A Guide to the Selection of Cpst-Effactive Wastewater Treatment
Systems, Bechtel, Inc., U. S. Environmental Protection Agency,
Contract No. 68-01-0973 (May 1973).
IV-16 Estimating Costs and Manpower Requirements for Conventional
Wastewater Treatment Facilities, Black and Veatch Engineers,
U. S. Environmental Protection Agency, Project 17090DAN,
Contract No. 14-12-462 (October 1971).
IV-17 Cost and Performance Estimates for Tertiary Wastewater Treating
Processes, FWPCA Advanced Waste Treatment Research Laboratory,
Report No. TWRC-9 (June 1969).
- 61 -
-------
CHAPTER V
SLUDGE AND RESIDUE TRANSPORT
INTRODUCTION
Sludge handling between unit processes within a wastewater treatment
facility is well established and is normally an integral part of the overall
design of the facility. The major concerns lie with transport of sludge
either to other facilities for further treatment or to an ultimate disposal
site. The following sections discuss the pertinent features of the primary
modes of transport, namely pipeline, rail, truck, and barge.
PIPELINE
Piping of solids suspended in liquid, including coal, limestone, and
sewage sludges, has been practiced for many years as shown in Table V-l.
It is also considered practical to batch different solids in the same
slurry movement as is done with petroleum products (Ref. V-2).
The hydraulics of sludge flow is complicated because of its varying
nature. Below about five percent solids, sludge resembles a fluid with
respect to friction considerations and power required for pumping. Above
about six percent, power requirements for pumping long distances generally
become prohibitive (Ref. V-2).
The velocity of flow during pumping of slurries is an important con-
sideration. Turbulence of flow is necessary to prevent the deposition of
suspended solids. Figure V-l indicates the influence of suspended solids
upon minimum velocities required for turbelent flow. For solids concentra-
tions above five percent, required flow velocities are higher than is
generally considered economically achievable. However, larger pipe diameters
in excess of ten inches can permit higher solid concentrations and still
be economically feasible.
Problems can arise in using pipeline transport. Grease can build up
on the inside walls of unlined pipe creating a restricted flow. Grit
deposited in the pipe during low flow or no flow conditions may cause a
temporary increase in the internal pipe roughness.
In the development of pipeline transport systems, consideration must
be taken as to the pipeline route and its reliability of service. Where
pipeline routes must traverse heavily traveled or recurring construction
areas such as metropolitan centers, proper attention must be given to
methods of construction, route alignment and rights-of-way, and limited
access provisions to insure protection of the pipeline integrity, environ-
mental protection, and minimization of public disruption. Pipeline
design must insure monitoring and operational techniques and procedures
to anticipate, correct, or ameliorate damage to the pipeline and the
surrounding environment due to pipe failure, rupture, or sabotage.
- 62 -
-------
tq cy
1) D. ^
>< O O
.C Ol "O
CO U -H
-H t-l rH
-------
FIGURE 3C-I
HYDRAULIC CHARACTERISTICS OF SLUDGE SOLIDS
Q>
-------
RAIL
Sludge can be hauled in rail tank cars as a liquid and in either open
or closed hopper cars as dewatered solids. At the present time, however,
rail haul of sludge is not widely practiced.
Hauling dewatered sludge is similar to hauling coal or ore. Similar
loading and unloading facilities and cars may be used. An earlier study
has noted that rail transport will become increasingly important in the
development of waste management systems (Ref. V-3). Combining dewatered
sludge and municipal solid wastes may offer a convenient and economical
solution to the disposal of both substances (Ref. V-2). Transporting
dewatered sludge in empty coal cars on their return to strip-mined areas
may reduce the unit-train costs and provide a greater utilization of rail
car and track capacity.
Rail haul rate structures are complicated. Five different rate
structures for five geographical areas of the United States exist (Ref.
V-2). Rates within these boundaries are not proportional to haul distances
nor to the type of material being hauled. Abrupt changes in rate structure
and classification may occur at both state and geographical boundaries.
TRUCK
Truck transport of liquid sludges in tank trucks or dewatered sludges
and ash in dump trucks is the most common method of transportation used. It
provides flexibility of operation in that sludge can either be taken directly
to a final disposal site or to an intermediate transfer point such as a rail-
road yard or barge loading dock.
As with rail transport, truck rate structures and acceptable routes
are determined by the Interstate Commerce Commission. What may look to be
the most direct route may not be the one allowed. Truck transport must
also consider the route from a safety and noise impact standpoint. Sub-
stantial truck traffic may be expected to occur when large volumes of
sludge must be transported either in a liquid or dewatered state. Truck
noise is attributed principally to unmuffled exhausts on diesel engines
(Ref. V-4). Consequently, heavy truck traffic must be routed around
quiet zones such as hospitals. In addition, routes by areas with heavy
pedestrian use such as schools should be avoided.
BARGE
Barging of sludges either in a liquid or dewatered state offers high
capacity, but it is a slow means of transportation. Problems, particularly
with odors, may occur during storage at dockside prior to barge trips.
The Chicago Metropolitan Sanitary District currently hauls 9000 tons (8160
metric tons) of wet sludge per day 188 miles (302 kilometers) down the
Illinois River prior to off-loading, storage in lagoons, and spray irrigation
on farmland (Ref. V-2).
- 65 -
-------
Table V-2 indicates the type of waste, barge capacity, and discharge
characteristics for ocean disposal.
Two types of barges, towed or self-propelled, employing either pumped
or gravity discharges may normally be used. The City of New York uses an
automated 6300 ton (5700 metric tons) barge 226 feet long, 56 feet wide,
and 20 feet deep (69 meters long, 17 meters wide, and 6 meters deep)
with an unloading time of 30 minutes. The City of Philadelphia uses
an 8000 ton (7250 metric ton) barge hauling digested sludge.
ECONOMICS
Variables affecting the costs are the mode of transport, volume of
sludge to be moved, solids content, and transport distance. The total
transportation costs include allowances in the case of rail, truck, and
barge for operation, maintenance, and fixed charges on loading and unload-
ing facilities as well as the transporting vehicles.
Figure V-2 shows pipeline installation costs as a function of
through-put (i.e. pipe diameter) for downtown, suburban, and rural con-
struction. Figure V-3 shows the remaining capital costs as a function
of distance transported for various through-put levels. Both figures will
then include the total capital costs of the pipeline system such as
installation, pipe, pump stations, rights-of-way, and indirect costs.
Figure V-4 indicates the annual direct operation costs such as power,
labor, supplies, and maintenance as a function of distance for various
through-put levels.
Rail costs on both a wet and dry basis are shown in Figure V-5. It
should be noted that rail costs could be cut in half were unit trains
utilized (Ref. V-2).
Tank truck transportation costs are shown in Figure V-6 for a variety
of liquid sludge solids content. Dump truck transport costs of dewatered
sludges are shown in Figure V-7 and for ash in Figure V-8.
Barge transportation costs for ocean disposal (capital and maintenance)
have been estimated in Table V-3 based upon a figure of $340 per ton represent-
ing the purchase cost of newly constructed barges (Ref. V-5 and considering
price of materials and labor having risen approximately 200 percent since
1965). Service life of ocean barges varies between ten and twenty years.
The primary barge life will be assumed to be ten years, while a secondary
standby barge of 1000 ton (908 metric ton) capacity will be twenty years.
Annual costs are based upon a seven percent interest rate, equal replace-
ment costs, adn no salvage value. Maintenance costs are assumed to be
twelve percent of the annual capital costs (Ref. V-5).
Towing costs are influenced by discharge rate, tug speed and distance
traveled. Based upon a rate of $100 per hour, tug speed of six knots
(6.9 miles per hour), and an unloading time of 1.5 hours, Table V-4
determines the costs per round trip distance in miles.
- 66 -
-------
CN
I
CO
a
•H
CO
•rl
J^J
cu
4J
CJ
CO
M
CO
JC
U
cu
00
i_(
CO
r^
a
CO
•H
P
cu ^
oo a
r-l -H
CO CU g
cj cO co
TO Pi a
•H 0
0 S
00 /^
a -a co
•H CU 4J
;s cu o
o P. a
H W W
v-'
00
M C
CU -H
rQ U
0 cd
3 Oi
!S w
CO
CU CU CU
a, N js
•H -H O
P-i co C
H
"^y
CU
ft
J>*,
EH
CU
00 O ^ 4-1
cd «j cu
M .*"• r£* CU
CU 4J CJ pti
> P, CO ^
•< cu -H
P Q
cu
4J
CO
cd
^
4-^
o
cu
ft
H
•H M
0 C
CO O
CO*^
O
ff\
CO
1
OO vO
r~- rH
in in o
• • •
oo oo vo
4J 4J 4J
o o en
m »n <•
cs> CHJ CH^
CN CN CN
CN 1 CN
rH 1 rH
*T3 4J t3
CU iH CU
A, > Cu
FH CO fi
3 M 3
PH O AJ
O O O
rH rH rH
T3
3
6
00
|3
13 "H T3
•H ^3 -H
CJ CO CJ
cd cd cd
I S I
C C
O CU O
H H H
MOM
O O
0 0
§«
V4
P-i O
1
00 1
cu
00
*rj
CO co 3
13 C -H rH
CU O J2 M
CO M rH Tj
Pi CO CU (!)
•HO -D 4J
r4 O CO CO
OH rH CU
rH ID -H 00
»G Ps ?^< *H
CJ 33 FM P
O O
0 0
M O
IH" oo"
o
rH
CN
1
1
1
1
CU
00
Tj
rH
in
13
CU
4-1
co
CU
00
•H
P
^
^4
o
o
m
vO
0
o
CN
1
0
o
rH
1
1
P*
£3
3
t)
^J
4-1
O
m
4J
•H
£»
cd
)"4
O
o
CN
1
I"**
rH
rH
•H
O
P.
C/3
0)
00
'O
(U
M
P
O
m
CO
-v, W
co C
to O
CU 4J
4J
0) CJ
•H CU
x a
CN
n oo
in r^
oo o
co
4J CO
o a
CO
H
CU
4-1
(1)
w B
>-< -H
O 4-1
4J «3
cu cu
S o
II II
oo -3-
-3- m
o •
f> CN
ox
cu
4-J X
cu o
cu C
CU.
4->
O
in
I
>
CU
ps|
cu
o
i-i
-------
1000
900
800
§ 700
o
T3
,_ 600
a>
o.
in
i_
£
o 500
U)
O
O 400
300
FIGURE
ECONOMICS OF PIPELINE TRANSPORTATION
OF DIGESTED SLUDGE
PIPELINE INSTALLATION COSTS vs CAPACITY
FOR THREE CONSTRUCTION ZONES
3E -2
V)
200
100
T 1 1 [-
T
T
BASIS • Sludge at 3 1/2% solids by weight
Pipeline operating factor 0.95
RURAL CONSTRUCTION
I I I I I I
I
SUBURBAN
I
CONSTRUCTION
I I I I
2OO
400
600
800
1000
I20O
1400
PIPELINE THROUGHPUT, tons dry solids per calendar day (365 days/year)
SOURCE'• Reference 3E-I
- 68 -
-------
FIGURE 3C-3
ECONOMICS OF PIPELINE TRANSPORTATION
OF DIGESTED SLUDGE
CAPITAL COSTS (Excluding Installation) vs DISTANCE
F
^ 2200
2 2100
o
1 2000
w 1900
a 1800
'5.
1700
o»
c
•o 1600
x 1500
£ 1400
1300
u.
°- 1200
c
2 noo
f 1000
TJ
v. 900
a>
Q.
800
2 700
0
10 600
O
° 400
< 300
CL 200
O
100
0
(
OR VARIOUS THROUGHPUT LEVELS
i i i i i i i i i i i i i i
\ BASIS = Sludge at 3 1/2% solids by
_ \ weight _
\^ Pipeline operating factor 0.95
\^
^*>^^ 25 TONS SOLI PS /DAY
- -
_ _
_
_ —
\
_ V
^-x^_ 50
- —
;\ :
^V,^ 100
— _
- Vs-*^ 250
- •- 500
^ 1000
1 | 1 1 1 1 1 1 1 1 1 1 1 1
3 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
TRANSPORTATION DISTANCE, miles
SOURCE1 Reference 3T-I
- 69 -
-------
FIGURE IT-4
ECONOMICS OF PIPELINE TRANSPORTATION
OF DIGESTED SLUDGE
DIRECT OPERATING COSTS vs. DISTANCE
FOR VARIOUS THROUGHPUT LEVELS
400
E
i
c
o
_>>
6
u>
V_
J3
"o
co~
CO
o
o
o
z
f-
o:
UJ
Q.
O
o
LU
IT
O
Z
z
300
200
100
TONS SOLIDS/DAY
r
25
BASIS: SLUDGE AT 3'/2% SOLIDS BY WEIGHT
OPERATING FACTOR 0.95 COSTS
INCLUDE POWER, LABOR, SUPPLIES
AND MAINTENANCE
50
10 20 30 40 50 60 70 80 90 100. 110 120 I3O 140 150
TRANSPORTATION DISTANCE - MILES
SOURCE^ Reference 3Z-I
- 70 -
-------
FIGURE 3Z:-5
1000
800
600
500
400
300
^ 200
o
2
O
100
80
cc
Q 60
tE 50
LU
a. 40
en 30
o
o
20
10
10
ECONOMICS OF RAIL TRANSPORTATION
(NOT ON A UNIT TRAIN BASIS)
i i i i i i 11
DRY BASIS
3.5% SOLIDS
WET BASIS
3.5% SOLIDS
I I I 1 I I I I
I i i i
100
50
40
30
in
20 a
"o
T3
10 o
LU
3
2
CO
o
o
20 30 40 50
100
200
500
1000
DISTANCE TO DISPOSAL POINT, miles
SOURCE •• Reference IE - 2
- 71 -
-------
FIGURE 3C-6
ECONOMICS OF TANK TRUCK TRANSPORTATION
1000
500
400
300
200
100
Jr 50
1 40
30
Z
2 20
DC
O
tr
UJ
a.
to
o
o
10
i I i i i i 111
DRY BASIS - 3.5% SOLIDS XV
DRY BASIS -
9% SOLIDS
DRY BASIS - 5% SOLIDS
BASIS -
3.5% SOLIDS
I I I I I I I I
I I I I I I I I I
100
50
40
30
20
10
5%
IU
UJ
a.
.5 I-
A W
4 o
, o
2 345
10 20 30 50 100
500 1000
DISTANCE TO DISPOSAL POINT, miles
SOURCE: Reference 3T-2
-72-
-------
TABLE V-3
ANNUAL CAPITAL AND MAINTENANCE COSTS FOR BARGING OPERATION
(Ocean Disposal)
Barge
Capacity
(tons)
1000
2000
3000
4000
5000
6000
Capital
Primary
Barge
$ 48,409
96,818
145,227
193,636
242,045
290,454
Cost
Secondary
Barge
$ 32,093
32,093
32,093
32,093
32,093
32,093
Annual
Maintenance
Cost
$ 9,660
15,469
21,278
27,087
32,897
38,706
Total
Annual
Cost
$ 90,162
144,380
198,598
252,816
307,035
361,253
TABLE V-4
TOWING COSTS FOR
(Ocean
Round Trip
Distance
10
25
50
100
150
200
300
BARGING OPERATIONS
Disposal)
Towing Costs
$/Trip-Mile
29.50
20.50
17.50
15.99
15.50
15.25
14.99
Figure V-9 indicates the limiting number of trips per year for barge
sizes.
Figure V-10 indicates the costs for inland barging of -liquid sludges.
- 73 -
-------
FIGURE 3T-7
TRANSPORTATION COSTS FOR DEWATERED SLUDGES BY
DUMP TRUCK (20-25 CU. YD. CAPACITY) FOR
30% TO 70% SOLIDS
(SPECIFICALLY EXPERIENCE AT CHICAGO MSD)
Q
CO
O
UJ
£
UJ
o
o
O
V)
O
O
2.10
2.00
1.90
1.80
1.70
1.60
1.50
1.40
1.20
1.10
1.00
I
I
I
I
I
I
I
I
6 8 10 12 14 16 16 20 22 24 26
TRUCK DISTANCE, MILES ONE-WAY
28
NOTE: Cost Paid To Private Haul Contractors
SOURCE: Private Communication With Mr. Donald Harper of the
Chicago Metropolitan Sanitary District
- 74 -
-------
FIGURE 3T-8
ECONOMICS OF DUMP TRUCK TRANSPORT
OF SLUDGE ASH
i.oo
10
20
30
40
50 60 70 80 90 100
DISTANCE TO DISPOSAL POINT, miles
- 75 -
-------
FIGURE 3L-9
l i l
o:
<
UJ
rv
CC
UJ
o
U.
CO
CD
UJ
o:
-------
FIGURE E-IO
TRANSPORTATION COSTS FOR LIQUID SLUDGES
BY PRIVATELY OWNED AND CONTRACTED
TOWED BARGE ON INLAND WATERWAYS
(SPECIFICALLY THE TENNESSEE RIVER SYSTEM)
2.10
UJ 2.00
O
3 1-90
to
to '-80
o
d '-7°
to
>S 1.60
.VJ 1.50
1.40
1.30
^ 1.20
Z
P 1.10
^ 1.00
v.
— 0.90
k
g 0.80
O
or
o
i r
I
I
J
I
I
I
20 30 40 60 80 90 100 120 140 160 180 200 220 240 260
TOWING DISTANCE, ONE-WAY RIVER MILES
NOTE: Not Included in the Above Costs Are the Following:
I. Dock Structures or Material Handling Facilities
2. Storage at Loading or Discharge Points
SOURCE: Private Communication With Mr. Patrick 0 Connor of the
Tennesse Volley Authority
- 77 -
-------
CHAPTER V
REFERENCES
V-l "Economics of Regional Waste Transport and Disposal Systems,"
Thompson, T. L., Snoek, D. E., and Wasp, E. J., presented at the
Third Joint AICHE-IMIQ Meeting, Denver, Colorado (September
1970).
V-2 Sludge Handling and Disposal - Phase I, State of the Art, pre-
pared for the Metropolitan Sewer Board of the Twin Cities Area
by Stanley Consultants (1972).
V-3 Rail Transport of Solid Wastes, report to the Department of
Health, Education, and Welfare by The American Public Works
Association Research Foundation (October 1968).
V-4 Transportation Noise; Impacts and Analysis Techniques, Nelson,
K. E. and Wolsko, T. D., Argonne National Laboratory report
ANL/ES-27 (October 1973).
V-5 The Barged Ocean Disposal of Wastes. A Review of Current Practice
and Methods of Evaluation, Clark, B. D., Rittall, W. F.,
Baumgartner, D. J., and Byram, K. V., U. S. Environmental Pro-
tection Agency, Pacific Northwest Water Laboratory (July 1971).
- 78 -
-------
CHAPTER VI
CHARACTERIZATION OF ULTIMATE DISPOSAL AND RESOURCE/RECOVERY METHODS
INTRODUCTION
Handling of residual wastes must be solved by one of the following
routes or combination or routes: (1) elimination of the source of wastes,
(2) recycling or by-product use, and (3) disposal to the environment. For
municipal wastes, elimination is impossible. Disposal and recycling to
the environment remains the most feasible alternative. Therefore, the
prime questions become where and how and in what form will municipal
residual wastes be reintroduced into the environment. The disposal of
municipal residual wastes will ultimately have an impact upon the atmo-
sphere, land, or ocean (realizing that surface water is a transient con-
veyance mode to the ocean) as ultimate sinks. Ecological and cost con-
siderations, particularly in light of recent and projected energy supply
problems, impose increasingly great constraints on ultimate disposal
methods. Land disposal of residual wastes, particularly for possible
nutrient recovery and reuse, presents an alternative that is receiving
much attention. Moreover, it must be recognized that the mass application
rate to land surfaces is becoming increasingly greater compared to such
convenient sinks as the ocean. This in turn means that land area may
become limiting. Well-engineered marine disposal systems have been con-
structed and have proven successful. Ocean outfall diffusers in use on
the West Coast provide very high dilutions and have shown little, if any,
adverse effects upon the ocean environment. However, poorly designed
ocean dumping systems exceeding the ocean site capacity may significantly
degrade the ocean site and its utilization as a food supply and recrea-
tional area.
The purpose of this chapter is to provide a technical background for
the ultimate disposal methods considered in this report. These methods
include: (1) sanitary landfills, (2) sludge recycling, (3) land reclama-
tion, (4) waste disposal ponds, and (5) ocean disposal. Moreover, in this
chapter the characteristics of residual wastes are evaluated relative to
the various aspects of the ultimate disposal methods. It is perceived
that the combination of general technical background and specific applica-
tion of the disposal methods to municipal wastewater wastes will provide a
comprehensive view of the disposal problem of such wastes.
Disposal of residual waste may not be necessary when an economical use
for the sludge exists, either directly or indirectly by sludge processing
with product recovery. The total cost of the wastewater treatment system
may be reduced when sludge becomes a profitable commodity. In viewing
sludge as a resource, the resource recovery methods discussed in this
chapter are: (1) incineration, (2) pyrolysis, (3) lime reealcination,
(4) composting, and (5) sludge reuse.
- 79 -
-------
Each disposal method is discussed separately with topics covering
historical and institutional perspectives both past and present, and general
operational procedures used in the disposal method. In addition, the waste
characteristics pertinent to the disposal method are discussed and con-
trasted to those of various municipal residual waste types. Siting
criteria, environmental effects, monitoring provisions, institutional con-
straints, management agency control and monitoring programs, and costs are
also discussed within each section relative to the disposal of these wastes
by the particular disposal method. Finally, the ultimate disposal methods
are compared to each other according to various socioeconomic, environmental,
and operational criteria.
SANITARY LANDFILLS
Introduction
A sanitary landfill has been defined as "...a method of disposing of
refuse on land without creating nuisances or hazards to public health or
safety, by utilizing the principles of engineering to confine the refuse to
the smallest practical volume, and to cover it with a layer of earth at the
conclusion of each day's operation or at such more frequent intervals as
may be necessary" (Ref. VI-1). The primary objective of any solid waste
disposal process is to reduce the volume of the refuse in order to maximize
the storage capacity of the site (Ref. VI-2). In sanitary landfilling,
volume reduction is done initially by the mechanical compaction of the
refuse prior to its burial. As the landfill ages (i.e., degrades), further
volume reductions occur as a result of overburden-induced densification and
removal of materials by gas and leachate production. Properly operated
sanitary landfills can reduce municipal refuse volume by two-thirds
(Ref. VI-2).
Municipal refuse is a complex heterogeneous collection of substances
which can and, in some cases, does include sewage and water treatment
sludges. Current EPA guidelines on land disposal are modeled after sani-
tary landfill operational and design characteristics, with a strong
emphasis on the minimization of environmental impacts during and after
disposal operations (Ref. VI-3). Existing and proposed state and local
guidelines on land disposal (open dumping) of solid wastes, in general,
are in keeping with those of EPA; and, over the long run, sanitary land-
fills can be expected to predominate.
There are many advantages associated with using the sanitary landfill
method of disposal of solid wastes compared with other methods such as
incineration or ocean dumping. The Bureau of Solid Waste Management (1969,
now of EPA) has cited the following as advantages of a sanitary landfill:
- 80 -
-------
(1) where land is available, a sanitary landfill is usually the
most economical method of solid waste disposal;
(2) the initial investment is low compared with other disposal
methods;
/
(3) it is a complete or final disposal method as compared to
incineration and composting which require additional treatment
or disposal operations for residue, quenching water, and
unusable materials;
(4) it can be put into operation within a short period of time;
(5) it can receive all types of solid wastes, eliminating the
necessity of separate collections;
(6) it is flexible and increased quantities of solid wastes can be
disposed of with little need for additional personnel and
equipment; and
(7) submarginal land may be reclaimed for use.
The disadvantages cited by the Bureau include:
(1) in highly populated areas, suitable land may not be available
within economical hauling distance;
(2) proper sanitary landfill standards must be adhered to daily or
the operation may result in an open dump;
(3) sanitary landfills located in residential areas can result in
extreme public opposition;
(4) a completed landfill will settle and require periodic main-
tenance ;
(5) special design and construction must be utilized for buildings
constructed on completed landfill because of the settlement
factor; and
(6) methane and other gases produced by decomposition of the wastes
may become a hazard or nuisance problem and interfere with use
of the completed landfill.
The principle disadvantages of sanitary landfilling are associated
with the aging or long-term degradation of the fill. Subsidence and
methane gas production limit the reuse possibilities of the site for many
years after disposal operations are completed. Sewage sludges introduced
- 81 -
-------
into a sanitary landfill can be expected to contribute significantly to
these problems.
Operational Characteristics
There are three general types of sanitary landfill construction,
their applicability largely dependent on topography and cover material
availability.
(1) The trench method (trench-fill or cut-and-cover method) is used
in areas of flat or gently sloping topography. This method
generally requires that the site can be trenched with conven-
tional earth-moving equipment and that water-table levels be at
least lower than the depth of cut. When completed, the landfill
consists of a series of long, narrow cells in parallel rows.
Cover material is obtained on site from the excavation of adjacent
trenches. The finished grade is usually higher in elevation than
the original ground surface.
(2) The area method (area-fill or fill-and-cover method) is used in
low lying areas, such as tidelands, marshes, or swamps, and in
land depressions such as abandoned quarries, ravines, or canyons.
Refuse is dumped on the existing ground surface, spread in hori-
zontal layers, and compacted. Cover material is provided by
excavation of the earth in front of the working face of the land-
fill or, if excavation on-site is not possible, by importation of
earth from another location. The finished fill consists of a
series of cells in layers and results in a significant increase
in the surface elevation of the site.
(3) The ramp method (progressive-slope method) is used exclusively in
filling natural or man-made depressions (e.g., ravines, canyons,
quarries, etc.). Refuse is deposited and spread in layers at an
angle against the side of the depression to a design height which
can be greater than 15 meters (50 feet). Cover soil is placed on
the slope sides and top at regular intervals.
Waste Characteristics
There have been significant changes in the proportionate amount of the
types of waste which have been introduced into sanitary landfills. The
widespread use of garbage grinders has decreased the amount of garbage (i.e.,
putrescible refuse) collected as solid waste while increasing the organic
loading at sewage treatment facilities, resulting in greater sludge
quantities. The increased use of throw-away paper, plastic, and glass con-
tainers has led to increases in this type of refuse (Ref. VI-4).
- 82 -
-------
The key characteristics of refuse (including sewage sludge) during the
operation of the sanitary landfill are its compactability and its bearing
strength. The mechanical compaction of the refuse by large bulldozers is
an important step in maximizing the available storage capacity of the site
and minimizing the effects of subsidence. The bearing strength of the
refuse determines in large part the type of landfilling which can be done.
Refuse with an overall low bearing strength such as wet sludge solids will
not be amenable to ramp-type landfilling operations as relatively low-angle
slopes will fail under minimal loads. Table VI-1 (Column 2) shows the
general character of various types of refuse in sanitary landfills.
Because of the operational difficulties and volume requirements encountered
with liquid sludges, general practice has preferred that sewage sludges be
dewatered (10-15 percent dry solids). However, even dewatered sludges have
poor engineering properties in that they are largely incompressible and have
little bearing strength. Consequently, special operational techniques such
as trenching or mixing with large quantities of refuse must be utilized for
sludge disposal. Over time, the dewatering of the sludge will add signifi-
cantly to landfill subsidence.
TABLE VI-1
CLASSIFICATION OF SANITARY LANDFILL MATERIALS
Material
(1)
Character in Fill
(2)
Deterioration
(3)
Garbage
Fibrous Organic:
Wood Paper
Tires
Small Metal: Cans,
etc.
Large Organic:
Stumps
Large Metal
Building Debris
Ashes
Wet, Compressible, Weak
Compressible
Very Resilient
Can be Compacted
Resist Compaction
Resist Compaction, Loose
Compressible
Compressible and can be
Compacted
Compressible, Weak
Decay with Noxious
Gas
Decay with Methane
Formation
Will burn
Rust and Galvanic
Action
Will burn, decay, and
generate methane
Rust followed by
collapse
Little or none
Aggravate Corrosion
Source: Ref. VI-5
- 83 -
-------
Table VI-1 (Column 3) also shows the degradation effects of the
various types of refuse. Sewage sludges would be expected to degrade in a
fashion similar to garbage and fibrous organic material such as paper.
Consequently, sludges would contribute significantly to methane gas pro-
duction. Leachate production, at least initially, would be expected to
increase as the sludges dewater.
EPA guidelines currently recommend that sewage treatment sludges be
dewatered before being placed in a sanitary landfill. The guidelines state
further that sewage sludges be digested (or some equivalent treatment) in
order to reduce both operational and public health hazards associated with
biological wastes (i.e., fecal coliform bacteria and viruses). Raw sewage
sludges are classified as hazardous wastes under the EPA guidelines and
require special investigation before disposal is allowed (Ref. VI-3).
Siting/Environmental Considerations
Site selection criteria for a sanitary landfill include technical,
socioeconomic, and environmental considerations. The following is a
representative list of such criteria (Ref. VI-A, VI-6, and VI~7):
(1) Costs - Land values of the candidate landfill sites should be
compared by their present values in the community, potential
uses, and possible degradation of neighboring lands..
(2) Land Requirements - Sufficient land should be available to meet
the volume requirements of the service population for a reason-
able number of years.
(3) Land UseCompatibility - Candidate sites should comply with
local zoning regulations and planning documents.
(4) Accessibility - Candidate sites should have two or more all-
weather access roads.
(5) Character of the Land - The land at the site should not be so
rocky or swampy that equipment might be damaged or bogged down
when filling operations are attempted. Other natural conditions
which should exclude a site from consideration (unless
specifically designed for) are:
(a) hilltops and ridges,
(b) highly porous areas,
(c) swamps and marshes (except under a reclamation scheme),
(d) natural drainage channels,
- 84 -
-------
(e) wildlife sanctuaries, and
(f) flood plains
(6) Aesthetic Considerations - It is very important that a sanitary
landfill site does not constitute a public eyesore, especially
to residents of nearby housing. Odor and machine noise from
sanitary landfills can cause aesthetic objections. A distance
of at least 300 meters from the nearest highways and other
thoroughfares should be maintained unless adequate shielding by
natural barriers (land formations, streets, etc.) or man-made
structures are present. Sanitary landfills should be located
downwind from areas of human activity and residence whenever
possible to avoid odor and noise nuisance.
(7) Availability of Cover Material - A suitable and adequate source
of cover material should be available at the site or at an econom-
ical haul distance from the site. The ideal cover material is
sandy loam (50-60 percent sand, 20-25 percent silt, 20-25 percent
clay). However, any well-graded soil with good composition and
low shrinkage properties is suitable.
(8) Haul Distance - Landfill sites should be located where they are
closest to the sources or refuse within the ranges dictated by
other site selection criteria. Where a regional or inter-
service landfill is used, it should be located equidistance from
all the stations served inasmuch as practicable. Where long-
haul distances are made necessary (over about 9 kilometers,
5.6 miles), use of large trailer trucks or railcars as well as
transfer stations may become necessary. One large site should
be favored over a number of small sites even if the former may
require slightly higher haul expense.
Resources that are utilized or may be impacted by disposal or residual
wastes such as sewage sludges and incinerator ash to sanitary landfills
include:
(1) Water Quality - Without adequate design measures to mitigate
leaching and surface runoff, residual waste disposed to sanitary
landfills may cause:
(a) degradation of subsurface and surface water supplies by
leachates;
(b) degradation of surface water supplies by runoff; and
(c) chronic deterioration of ecological conditions in
receiving waters.
- 85 -
-------
(2) Air Quality - Nocuous and potentially hazardous gas (methane)
may be exposed and dissipated to the atmosphere after discharge.
Possible impacts on air resources include the following:
(a) methane gas produced after abandonment may collect beneath
a structure subsequently built on top of the old disposal
site, thus producing a potentially hazardous (explosive)
situation;
(b) sludge is mixed with refuse before disposing to a sanitary
landfill so that a potential fire hazard is constituted.
Burning waste would cause smoke emission to the atmosphere,
thus degrading ambient air quality;
(c) during the daily application of soil cover, dust may be
generated which will deteriorate air quality; and
(d) inhabitants of the surrounding area are susceptible to
possible noxious odors from the sanitary landfill.
(3) Land Quality - Possible impacts upon land-related resources
include:
(a) prevention of other surface land use by occupation of
surface area by the disposal facility;
(b) clearing the land necessary for the landfill may allow
immediate erosion to occur;
(c) operation of the sanitary landfill by continually exposing
fresh soil during daily application of cover may allow
erosion to occur; and
(d) leaching through the bottom and sides of the landfill may
deposit contaminants in the soil beneath and adjacent to the
landfill's perimeter.
(4) Public Health - Possible impacts upon public health considerations
include:
(a) the presence of toxic substances and pathogens in some
residual wastes might damage public health if pathogens
and/or toxic substances contaminate subsurface water supplies
directly by leachates or surface water supplies by lateral
groundwater transport of leachates to surface waters;
(b) agricultural cultivation subsequent to abandonment of the
disposal site could produce crops that have incorporated
toxic substances in edible portions of the plant;
- 86 -
-------
(c) vectors of pathogens (e.g., insects and rodents) may be
attracted to the disposal site which could allow dissemi-
nation of pathgens to populations in the surrounding area;
(d) the presence of accidentally burning refuse at the disposal
site could present a fire hazard to the contiguous area; and
(e) dust and smoke from the site could possibly pose a health
problem to local residents.
Besides the hydrologic effects of increases in surface elevation,
changes in soil character, and the potential of on-site water ponding, the
degradation of the refuse (and sludges) within the landfill may have
serious potential impacts on the environment. Continuous long-term settling
along with organic decay and subsequent leaching may cause the sanitary
landfill to subside as both density increases and material is removed. Sub-
sidence occurs unevenly and unpredictably within a fill owing to the
different times of cell completion and the unique composition of each cell
(Ref. VI-8).
The leachate issuing from the landfill consists of very high concen-
trations of organic and inorganic compounds; values of NH^-N = 320 mg/1,
total nitrogen = 5357 mg/1, BOD5 = 77,050 mg/1 being reported (Ref. IV-9).
Few published data are available on the bacteriologic quality of landfill
leachate, but it is believed to be poor. Coliform counts of up to 7 x 10
per 100 millimeters on a simulation study (Ref. VI-10) and 7.4 x 10^ per
gram of refuse at a landfill (Ref. VI-9) have been reported. Depending on
the local hydrogeologic conditions, the leachate can pollute potential or
existing groundwater or surface water supplies.
Air does not penetrate a well-compacted landfill to any extent. As a
result, the organic material in a landfill decomposes anaerobically and
produces carbon dioxide, methane, and other gases. Much of the carbon
dioxide dissolves in the infiltrating water causing it to become weakly
acidic, and it is the first step in the production of the highly-concentrated
leachate. Methane tends to escape from the surface of the fill or through
adjacent lands. Closed structures (e.g., buildings) on or near the site
can trap methane which is explosive at relatively low concentrations (5-15
percent).
Suitability of Disposal
Municipal residual wastes differ greatly in their suitability for
disposal by the sanitary landfill method. Table VI-2 compares a repre-
sentative list of residual wastes against four basic evaluative categories:
(1) operational constraints, (2) institutional restraints, (3) potential
for leachate contamination, and (4) methane production. The qualifiers of
low, moderate, and severe are used only to indicate the relative
differences between the different types of residual waste.
- 87 -
-------
TABLE VI-2
SUITABILITY OF VARIOUS MUNICIPAL WASTEWATER TREATMENT PLANT
RESIDUAL WASTES FOR SANITARY LANDFILL DISPOSAL
Residual Waste
Biological Treatment
Primary Sludges
Undigested
Thickened
Digested
Activated Sludges
Undigested
Thickened
Digested
Sludge Cake
Ash
Wet Oxidation
Incineration
Chemical Treatment
Alum Sludge
Raw
Dewatered
Lime Sludge
Raw
Dewatered
Operational
Constraints
Severe
Severe
Severe
Severe
Severe
Severe
Moderate
None
None
Severe
Moderate
Severe
Moderate
Institutional
Constraints
Yes
Yes
No
Yes
Yes
No
No
No
No
No
No
No
No
Potential
Groundwater
Contaminat ion
High
High
High
High
High
High
High
Low
Low
Moderate
Moderate
Moderate
Moderate
Methane
Pro-
duction
High
High
High
High
High
High
High
None
None
Low
Low
Low
Low
- 88 -
-------
Operational constraints for a sanitary landfill relative to the
residual waste characteristics would be the high water content of the
underwatered sludges and potential leaching problems, low bearing
strength, and low solids volume. Within this context, the residual ash
from wet oxidation and incineration processes would be the most suitable
wastes and the undewatered biological and chemical sludges the least
suitable.
To insure adequate safeguards of public health and environmental
quality, regulatory institutions may impose operational constraints upon
the sanitary landfill. The landfilling of wastewater residuals is pri-
marily constrained by public health considerations, in particular, the
hazardous nature of raw (i.e., undigested) wastewater treatment sludges.
Such wastes contain large numbers of bacteria, viruses, and other patho-
gens. Digestion, dewatering, or incineration of wastewater sludges
significantly reduces the possibility of infection from handling and dis-
position of these wastes by removing 30 to 100 percent of the original
number of pathogens. General operational regulations may be based on sani-
tary landfill requirements recommended by the U. S. Environmental Pro-
tection Agency (Ref. VI-11).
Residual wastes are evaluated on their potential for groundwater contam-
ination by consideration of the solubilities of their components and the
resulting quality effects. The high organic content of unincinerated
wastewater sludges would be expected to provide high concentrations of
soluble organics and coliform bacteria to leachate waters. In addition,
chelation and low pH may cause the heavy metals found in such sludges and
surrounding refuse to leave the landfill in the leachate. Wet oxidation and
incineration ashes are composed largely of low-solubility silicates but do
contain some phosphates and other soluble salts.
Methane production is a function of organic matter content. As a
result, wastewater sludges would be expected to contribute a significant
amount to methane production within a sanitary landfill. Ashes and chemi-
cal sludges would contribute far less methane, owning to their low organic
matter content.
In general, wet oxidation and incineration ash and dewatered chemical
sludges appear to be best suited for sanitary landfill disposal. These
wastes present the fewest operational and environmental problems. The
biologic wastewater sludges, because of their high content of water and
organic matter, present serious operational and environmental problems
which would have to be compensated for in the design of the sanitary land-
fill.
- 89 -
-------
Management Agency Control and Monitoring Program
Control
A management agency nu.y control disposal of residual waste to sanitary
landfills using a permit system, land use regulations, and, to a lesser
degree, standards and disposal charges.
(1) General considerations of a permit system include:
(a) accurate description of disposal site;
(b) description of terrain alteration;
(c) existing and future land use of the surrounding area;
(d) projected use of the site after abandonment;
(e) environmental impact survey;
(f) existence of water resources and present or potential
utilization of them;
(g) chemical, physical, biological properties of the waste and
possible pretreatment required;
(h) monitoring requirements;
(i) general geologic character of the disposal site and adjacent
area including permeability and leaching properties of soil
and subsurface strata;
(j) highest probable annual groundwater table level and delinea-
tion of groundwater flow;
(k) documentation of need for disposal to a sanitary landfill and
discussion of disposal alternatives and reasons for rejection;
(1) description of the process that produces the waste;
(m) controls to mitigate erosion and surface runoff;
(n) prevention of accidental fires at the landfill; and
(o) inhabition of vector presence.
(2) Applicable standards controlling disposal of residual waste to a
sanitary landfill concern pretreatment and subsurface and surface
receiving waters which may be directly contaminated by leachates.
- 90 -
-------
Standards concerning groundwater quality are usually broad, based
on public health criteria. Surface water quality is usually
regulated by well-defined effluent discharge or receiving water
quality standards. Pretreatment standards that may be associated
with permit requirements are usually well defined. Pretreatment
standards are particularly stringent regarding moisture content
(usually 10-15 percent solids) and presence of pathogens.
Additionally, local units of government may promulgate regulations
controlling the presence of methane gas because it can constitute
a safety hazard.
General considerations of standards include:
(a) quantity and rate of waste disposed at the site;
(b) toxicity of waste input and/or in receiving waters;
(c) number of pathogens in waste input and/or in receiving
waters;
(d) bionutrients from waste in receiving waters; and
(e) compressibility and dewatering quality of waste input.
(3) General considerations of land use regulations concerning disposal
of residual waste to sanitary landfills include:
(a) existing land use/zoning of disposal site (this is a signifi-
cant control because sanitary landfills are usually close to
urban areas and may occur near a well-developed section);
(b) because of the erosion potential, regulations may constrain
the location of a sanitary landfill in the interests of soil
conservation; and
(c) preclusion of future alternatives to land use at the disposal
site.
Monitoring
To enforce regulations governing disposal of residual waste to sani-
tary landfills, general aspects of a monitoring program during operation
and after abandonment include:
(1) delineation of the presence and directions of subsurface
dispersion of waste constituents;
(2) surveillance of possible odorous gas produced at the site;
- 91 -
-------
(3) detection of the presence and amount of methane gas produced at
the site;
(4) measurement of the amount of subsidence after site abandonment
(Regrading may be necessary to mitigate leaching. Regrading can
prevent the formation of sag ponds that collect rain and can
decrease possible soil erosion.);
(5) detection of leachates transported to surface water;
(6) delineation of the amount and severity of surface erosion and
runoff to surface waters;
(7) seasonal variation in groundwater depth and direction of movement;
and
(8) deposition of toxic substances in soil.
Costs of Sanitary Landfilling
Where wastewater sludge is landfilled, typical costs may increase
due to more stringent environmental impact control, land costs, sludge
dewatering, and transportation of the waste to the site. Burd (Ref. VI-12)
provides the following costs for landfills (adjusted to June 1975):
(1) operating costs $0.95 to $3.80 per ton and (2) capital costs of $1.90
per ton. Figure VI-1 indicates a range of sanitary landfill capital and
operation and maintenance costs (Ref. VI-13). Additional landfill costs
presented as a function of transport distance are given in Figures VI-2,
VI-3, and VI-4. These curves indicate the relative change in total cost
of disposal as a function of distance. Land costs are not included, owing
to the great difference in cost of land even in a particular geographic
area. General land costs for the average value of one acre of farmland
(Ref. VI-15), March 1, 1974, are presented below.
(1) Average acre of farmland in New Jersey is $2,099.
(2) The states of Rhode Island, Connecticut, and Maryland are the
only states (other than New Jersey) with the average cost of
farmland greater than $1,000 per acre.
(3) The average cost of farmland in the continental United States
is $310 per acre.
The cost of sanitary landfills is low compared to several other ultimate
disposal methods. However, the increasingly higher price of land in con-
junction with greater waste transportation cost makes other ultimate dis-
posal methods worth examining closely in a given situation.
- 92 -
-------
FIGURE 21-I
CAPITAL AND 0/M
COST FOR
SANITARY LANDFILLS
6
4
2
z to
0
6
i <
~" 2
h-
§ 1.0
6
4
2
O.I
1
1 III 1 1
-
CONSTRUCTION COST
(EXCLUDING LAND) ~~V,
^^^^
- *r
_
_
—
1 III 1 1
02 4 6 100 2 4
QUANTITY (WET
NOTES'- 1. Minneapolis, June, 1975 ENR
2. Amortization of 7% for 20
3. Labor Rate of $6.25 Per H
4 Quantity Assumes 6 Day Work
5. Wet Sludge Must Be Considers
6. Source^ U.S.P.H.S. and Stanley
SOURCE : Reference 2E-I3
ii i ii
X-
-
^*""<"--— ^^^
-
^
—
ii i ii
6 1000 2 4 6 10,
6.0
4.0 a:
_j
i
2.0 §
u.
O
1.0
6 0
_J
4 =!
2 co
O
O
0.1 §
h-
6 g
a:
en
O
o
2
0.01
000
TON/DAY)
Construction Cost Index of 2200
Years
our
Week
d for Cost Per Ton
Consultants
- 93 -
-------
FIGURE 3ZI-2
COMPARATIVE COST (1966) OF SLUDGE DISPOSAL
BY VARIOUS METHODS
FOR CITY OF 10,000 INHABITANTS
O
•o
O
O
350
300
250
200
ISO
100
50
INCINERATOR
'ASH TO LANDFILL
LAND APPLICATION
'OF LIQUID
DIGESTED SLUDGE
DEWATERED
SLUDGE TO
LANDFILL
50
100
150
200
DISTANCE TO DISPOSAL POINT, miles
SOURCE^ Reference 21-14
- 94 -
-------
FIGURE "21-3
COMPARATIVE COST (1966) OF SLUDGE DISPOSAL
BY VARIOUS METHODS
FOR CITY OF 100,000 INHABITANTS
350
300
250
c
o
-------
FIGURE 3ZI - 4
COMPARATIVE COST (1966) OF SLUDGE DISPOSAL
BY VARIOUS METHODS
FOR CITY OF 1,000,000 INHABITANTS
o
in
o
o
•o
in
o
o
70
60
50
40
30
20
10
DEWATERED
SLUDGE TO
LANDFILL
INCINERATOR
ASH TO LANDFILL
LAND APPLICATION
'OF LIQUID
DIGESTED SLUDGE
50
100
150
200
DISTANCE TO DISPOSAL POINT, miles
SOURCE •• Reference 3ZI-14
- 96 -
-------
WASTE DISPOSAL PONDS
Introduction
This section is concerned with ultimate disposal of water and
wastewater treatment sludges to waste disposal ponds.
Lagoons are natural or artificial depressions in the ground which are
used for processing wastewater and sludges in various ways including
digestion of organic sludge, thickening, drying, storage, and ultimate
disposal. Only the use of lagoons as a means for ultimate disposal of
sludges will be examined in this section. Sludge lagoons are used for
ultimate disposal because of their ability to concentrate and contain
pollutants. Owing to their large surface areas, lagoons are susceptible
to high evaporation which, along with settling, dewaters the sludge and
reduces the volume. To a much less extent, drainage also dewaters the
sludge, causing a more compact mass. Through these means of liquid-solid
separation, solids remain in a local area where, by the design of the
lagoon, little environmental impact is incurred. Due to minimal environ-
mental effect and/or construction, operation and maintenance cost, sludge
lagoons are a popular means of ultimate disposal. However, because of
large land requirements and possible odor problems with organic sludges,
use of lagoons is generally restricted to small wastewater treatment plants
in rural areas of low population density where land is relatively inex-
pensive.
Few policy guidelines exist that specifically regulate the environ-
mental impact of lagoons. Most regulations are at the state level and
deal broadly with protection of groundwater resources, zoning laws, and
protection of the public from nuisances such as the presence of flies and
odors caused by lagoons.
Waste Characteristics
Sludge lagoons are suitable for ultimate disposal of both biological
and chemical wastewater sludges. Lagoons will accept both lime and alum
derived sludges, although alum sludge is not so easily compacted due to
difficulty in dewatering. Discharging the sludge in smaller volumes by
previous thickening or dewatering will enable a higher loading rate and/or
longer use of the lagoon. In disposing lime sludge, up to 20-40 percent
consolidation is possible and up to 50 percent if the supernatant is
drained off (Ref. VI-16). Disposal of digested sludge to lagoons is
generally more prevalent than undigested sludge because of reduced volume
and lower volatile solids content, i.e., more stabilized. Smaller plants
usually comprise the majority of facilities which dispose of undigested
sludge in lagoons due to the small amount of sludge generated, more avail-
able land, and fewer people to be affected by odors. While wastewater
treatment plants may dispose of their organic sludge, either digested or
undigested, at varying percent solids, only in a few instances do plants
also dump their residual grit into lagoons.
- 97 -
-------
Toxic qualities of sludge are of particular concern in regard to
transfer of toxic materials to ground water by percolation. Lagoon design
usually allows for improvement of the waterholding characteristics of the
bottom, or existing bottom soil porosity may be low so that leaching of
toxic materials is insignificant. Lagoons may have plastic bottom liners
(Ref. VI-17) to prevent drainage. If a high-percolation rate exists, the
disposed sludge must have a low level of pathogens (sludge digestion is an
effective disinfectant process) and especially low concentrations of
nitrogen and heavy metals.
Operation Characteristics^
Operation of wastewater treatment plant lagoons for ultimate disposal
is basically concerned with influent sludge, settling of the sludge and
supernatant flow if the lagoon is designed for supernatant discharge.
Quality as well as quantity of influent sludge is regulated to prevent a
rapid loss of disposal volume or an overflow of sludge or supernatant.
Influent is pumped or gravity fed into the lagoon. Typical loading of
raw solids is 96 kg/yr/cu m (160 Ib/yr/cu yd) (Ref. VI-12). Inlet structures
to achieve even distribution of sludge over the bottom may be fixed or
portable. If more than one lagoon exists, the lagoons can be filled alter-
nately. Sludge in the off-line lagoon can settle and the water associated
with the sludge evaporate. While lagoons are best suited to warm and dry
climates, lagoons are also operated in northern areas. Here, adequate
provisions for extra disposal volume must be made to allow for lower evapora-
tion and digestion rates. However, during the winter when the upper sludge
layer freezes, the subsequent spring thawing helps dewater the sludge. The
released water from the thawing process can then be drawn off to provide
additional storage capacity in the pond. If the lagoon is operated with
discharge or recycle of supernatant, then evaporation is not as significant
to water removal from the lagoon. While supernatant discharge from some
chemical treatment plant lagoons may be direct to natural receiving waters,
supernatant from biological treatment plant lagoons should be recycled back
through the wastewater treatment plant.
Siting/Environmental Considerations
Because of the containment character of lagoons, siting criteria are
not so stringent as most other methods of ultimate disposal. Prevention of
groundwater contamination by leachates is usually the most important
criterion to be met. To minimize leaching of contaminants to ground water,
a site should be selected with an impervious soil (i.e., high-clay content)
and/or a low water table. Various design methods exist to prevent percola-
tion through the bottom by reducing bottom permeability. These methods
include soil compaction, and the use of soil cement, asphaltic composition,
soil sealants, and various impermeable membranes (Ref. VI-18). Odor
problems may be associated with operation of sludge lagoons. Such facilities
should therefore be located in an area of low population density or at
least be located downwind of local dwellings.
- 98 -
-------
For a higher evaporation rate (for volume reduction), sludge lagoons
are best suited to warm, dry areas. A warm climate aids sludge digestion
and prevents typical spring odor problems which occur in colder areas as
ice cover melts.
Resources that are utilized or may be impacted by disposal of residual
waste to waste disposal ponds include the following:
(1) Water Quality - Disposal of residual waste via waste disposal
ponds designed to drain the waste or by leakage will utilize the
carrying capacity of available ground water. Possible impact
on other resources includes the degradation of subsurface and
surface water supplies by leachates, the degradation of surface
water supplies by surface runoff (after site abandonment), and
chronic deterioration of ecological conditions in receiving
waters.
(2) Air Quality - Noxious and potentially hazardous gases such as
methane may be exposed and dissipated to the atmosphere. Inhabi-
tants of the surrounding area may then be subjected to nocuous
odors from the disposal site.
(3) Land Qua1ity - Possible impacts upon land-related resources
include:
(a) prevention of other surface land use by occupation of
surface area by the disposal facility;
(b) during construction, clearing the land necessary for
surface facilities will probably cause immediate, temporary
erosion; and
(c) leaching through the bottom and sides of an unlined pond
may deposit contaminants in the soil beneath and adjacent
to the pond's perimeter.
(4) Aesthetics - Presence of the waste disposal ponds may disrupt the
existing land use composition of the adjacent area.
(5) Public Health - Possible impact upon public health considerations
includes:
(a) the presence of toxic substances and pathogens in some
residual wastes might damage public health when pathogens
and/or toxic substances contaminate subsurface water
supplies directly by leachates or surface water supplies
by lateral groundwater transport of leachates to surface
waters;
- 99 -
-------
(b) agricultural cultivation, subsequent to abandonment of the
disposal site, could produce crops that have incorporated
toxic substances in edible portions of the plant; and
(c) entrapment of methane gas beneath structures built upon an
abandoned site produces a potentially explosive situation.
Suitability of Disposal
In considering various ultimate disposal methods for wastewater treat-
ment plant residual wastes, the general suitability of the waste to a
particular disposal method can be readily ascertained by reviewing sig-
nificant attributes of the method in regard to waste properties. In
Table VI-3, a list of representative wastes is presented along with
specific attributes of waste disposal ponds. Evaluation terms used in
this table are based on both absolute and relative criteria.
While nearly any material can be disposed to a lagoon, in order to
fully utilize the available volume the sludge must be fluid enough to pump
and flow over the lagoon bottom. Those sludges which cannot flow in this
manner are operationally constrained and the wastes listed in Table VI-3
have been evaluated accordingly.
As concerns regulatory institutions, the Federal government does not
regulate disposal ponds. Most states have laws protecting groundwater
quality sufficiently broad to cover leaching from ponds, but most do not
have laws specifically regulating waste-disposal ponds. Due to the lack of
specific regulations, Table VI-3 indicates the existence of no institu-
tional constraints.
Where organic wastes are disposed by lagooning, objectionable odors
may be generated as biological stabilization occurs. This is particularly
true of relatively unoxidized organic waste. The representative sludges
in Table VI-3 are evaluated with respect to their relative potential for
causing odors based on their content of biodegradable matter.
Contamination of ground water underlying the disposal pond is possible
due to the leaching of components in the waste. These components include
pathogens such as bacteria and viruses, toxic materials such as heavy
metals and pesticides, and generally high concentrations of dissolved
solids. While conditions for appreciable leaching must be evaluated on a
case-by-case basis, the relative potential for contamination of ground
water by particular wastes is evaluated in Table VI-3.
Management Agency Control and Monitoring Program
Control
A management agency may control disposal of residual waste to waste
disposal ponds using a permit system, land use regulation, and, to a
smaller degree, standards.
- 100 -
-------
TABLE VI-3
SUITABILITY OF VARIOUS MUNICIPAL WASTEWATER TREATMENT PLANT
RESIDUAL WASTES FOR DISPOSAL BY WASTE DISPOSAL PONDS
Residual Waste
Biological Treatment
Primary Sludges
Undigested
Thickened
Digested
Activated Sludges
Undigested
Thickened
Digested
Sludge Cake
Ash
Wet Oxidation
Incineration
Chemical Treatment
Alum Sludge
Raw
Dewatered
Lime Sludge
Raw
Dewatered
Operational
Constraints
None
None
None
None
None
None
High
High
High
None
None
None
None
Institutional
Constraintsl
No
No
No
No
No
No
No
No
No
No
No
No
No
Odor
High
High
Moderate
High
High
Moderate
Moderate
Low
Low
Low
Low
Low
Low
Potential
Groundwater
Contamination
High
High
High
High
High
High
High
Low
Low
Moderate
Moderate
Moderate
Moderate
No institutional constraints are indicated owing to the lack of
specific regulations.
- 101 -
-------
(1) General considerations of a permit system include:
(a) accurate definition of disposal site;
(b) description of terrain alteration;
(c) existing and future land use of the surrounding area;
(d) projected use of the site after abandonment;
(e) environmental impact survey;
(f) existence of water resources and present or potential
utilization of them;
(g) chemical, physical, biological properties of the waste and
possible pretreatment required;
(h) monitoring requirements;
(i) general geologic character of site and adjacent area
including permeability and leaching properties of soil and
subsurface strata;
(j) highest probable annual groundwater table level and delinea-
tion of groundwater flow;
(k) documentation of need for disposal to waste disposal ponds
and discussion of disposal alternatives and reasons for
rejection;
(1) description of the process that produces the waste; and
(m) controls for preventing surface runoff from entering the
disposal pond(s).
(2) Applicable standards controlling disposal of residual waste by
waste disposal ponds concern pretreatment and subsurface and
surface receiving waters. Subsurface receiving waters may be
directly contaminated by leachates. Standards concerning
groundwater quality are usually broad and based on public health
criteria. Surface receiving waters may be directly susceptible
to pollution by erosion from the site after abandonment or
indirectly by groundwater-carried leachates. Surface water
quality is regulated by usually well-defined effluent discharge
or receiving quality standards. Pretreatment standards that may
be associated with permit requirements can be well defined.
General considerations of standards (pretreatment and receiving
waters) include:
- 102 -
-------
(a) quantity and rate of waste disposed at the site;
(b) toxicity of waste input and/or in receiving waters;
(c) potential for pathogens in waste input and/or in receiving
waters;
(d) bionutrients from waste in receiving waters; and
(e) thermal character of waste input.
Additionally, local units of government may promulgate
regulations controlling the presence of methane gas because it
may constitute a safety hazard.
(3) General considerations of land use regulations concerning dis-
posal of residual waste via waste disposal ponds include the
existing land use/zoning of the disposal site (this is a signifi-
cant control because disposal ponds are usually close to the
wastewater treatment plant, probably in a well-developed area)
and possible future alternatives to land use of the disposal
site.
Monitoring
Based on a thorough preliminary (predesign) investigation, a program
for monitoring the environmental impact of a sludge lagoon should focus on
typical problem areas such as groundwater contamination, odors, quality of
discharged supernatant, and maintenance of the inlet recycle pipelines.
Groundwater downstream of the lagoon should be sampled for quality.
Significant water properties to be analyzed are total dissolved solids,
nitrogen chemical species, and heavy metals. Odors can be monitored by
plant personnel reconnoitering the lagoon site. If supernatant is dis-
charged to natural receiving waters, its quality should be periodically
ascertained. Pipelines transporting sludge or recycled supernatant should
be checked for leaks or breaks. Despite the presence of bottom sealers,
leaks are possible and should be searched for. Such a leak may occur after
the ponds are abandoned.
To enforce regulations governing disposal of residual waste by waste
disposal ponds, general aspects of a monitoring program during operation
and after abandonment include:
(1) delineating the presence and directions of subsurface dispersion
of waste constituents;
(2) surveillance of odorous gas produced at the site;
(3) detecting the presence and amount of methane gas produced at the
site;
- 103 -
-------
(4) measuring the amount of subsidence after site abandonment
(regrading may be necessary to mitigate leaching by preventing
the formation of surface sag ponds or to decrease possible soil
erosion);
(5) detecting the presence of leachates in surface waters;
(6) delineating the amount and severity of surface erosion and
runoff to surface receiving waters;
(7) defining seasonal variation in groundwater depth and direction
of movement; and
(8) evaluating deposition of toxic substances in soil.
Cost of Waste Disposal Ponds
Waste disposal ponds or lagoons are usually used for waste treatment,
with eventual removal of accumulated bottom sludge to landfills or possible
use as a soil conditioner (as in sludge recycling). When use of disposal
ponds are a means of ultimate disposal, a new site must be selected and
developed for use whenever the pond's capacity is exceeded. Thus, the
total cost of the disposal pond is periodically incurred. An average
lagoon capital and operating cost (updated to 1975) ranges from $1.90 to
$6.65 per dry ton of solids handled (Ref. VI-12). These costs include
short-distance sludge transport (generally by pipeline). Construction
costs (updated to 1975) of lagoons can be estimated at an approximate
cost of $45,000 per acre (4.10 per ton per year) based on 20-year amortiza-
tion at seven percent interest (Ref. VI-19).
SLUDGED RECYCLING
Introduction
Sludge recycling represents an attractive alternative to other sludge
disposal methods in that it utilizes certain inherent characteristics of
sludges for agricultural benefits. Unlike ocean dumping and landfilling,
sludge recycling has the potential of offsetting capital and operating
expenses with improved soil conditions and crop production. Sludge
recycling is used in several communities in this country (Ref. VI-20,
VI-21, and VI-22) and has been used in Europe for over a century (Ref.
VI-23 and VI-24).
Sewage sludges contain macro plant nutrients (e.g., nitrogen,
phosphorus, and potassium) at levels that are about one-fifth those found
in commercial fertilizers. Biological sludges also contain necessary micro
nutrients. Ranges in levels of these nutrients found in sludges from various
areas of the country are shown in Table VI-4. The low nutrient levels found
in sludges compared to inorganic fertilizers require higher and/or more
applications of sludge in order to get results comparable to chemical
- 104 -
-------
TABLE VI-4
MINERAL NUTRIENTS - PERCENT OF DRY SLUDGE SOLIDS
Total Nitrogen
Organic Nitrogen
Phosphorus
Potassium
R£
3.5
2.0
0.8
0.2
mge
- 6.4
- 4.5
- 3.9
- 0.7
Source: Ref. VI-25
fertilizers. While commercial fertilizers may contain a prescribed amount
of nutrients, e.g., five percent nitrogen, ten percent phosphorus, and five
percent potash, digested sludge (Ref. VI-26) contains an average 2.4 per-
cent nitrogen, 2.1 percent phosphorus, and insignificant potash. However,
the slow-release of the organic nitrogen in sludges is a desirable
characteristic in that it provides a long-term nitrogen supply for crops
and minimizes nitrate contamination of ground water. In addition to the
nutrient value of sludges, their organic content aids in improving soil
conditions by increasing the water-holding and buffering capacities of
soils.
The long-term effects of sludge application on soils are not known
conclusively at this time (Ref. VI-27). Heavy metals, pesticides, and
polychlorinated biphenols are present in sludges and these are toxic to
plants and microbial life at low concentrations in the soil solution.
Fortunately, several soil processes make these toxic materials at least
temporarily unavailable to the life cycles within the soil. However, the
long-term impact of toxic compounds concentrating in the soil on the soil
productivity are not conclusively known.
Some of the advantages offered by sludge recycling are given below.
(1) It requires little or no additional capital expense at the
wastewater treatment site (except for storage during the cold
season).
(2) It recognizes sludges as a resource and utilizes them as such. Con-
sequently, costs incurred by this method can be offset to some degree
by the utility of the sludge to agriculture. Direct costs incurred
by sludge incineration or landfilling are not borne by the users.
(3) Certain sludges have sufficient quantities of nitrogen,
potassium, and phosphorus to be of some value as fertilizers.
- 105 -
-------
Sludge nutrients are released slowly, providing a long-term
supply of plant nutrients.
(4) Certain sludges have excellent soil conditioning properties.
(5) The high water-content of sludges can serve as supplemental
irrigation.
Some of the disadvantages of sludge recycling are given below.
(1) The relatively low available nutrient concentrations in sludges
may require enrichment with chemical fertilizers.
(2) In some instances, a municipality would be competing with private
enterprise for a market.
(3) There is no real tradition or precedent in American agriculture
comparable to sludge recycling.
(4) Many sludges, including most chemical sludges, are unsuitable for
recycling. For most municipalities, then, sludge recycling is
only a partial solution to sludge disposal.
(5) There are many operational constraints, such as cold season
storage of sludges, the daily weather variations, and relatively
low application rates, which lead to extensive contingency plan-
ning.
(6) The long-term effects of sludge application to soil have not
been adequately researched. Soil toxicity may occur after long
periods of sludge application (Ref. VI-23) .
(7) Possible contamination of groundwaters with heavy metals, toxi-
cants (pesticides), and salts (TDS) may occur.
Considerable effort has been expended within the past few years by the
Environmental Protection Agency, Army Corps of Engineers, and various uni-
versities and communities on pilot studies and demonstration projects
directed toward the applicability of land treatment for wastewater effluent
and sludges (Ref. VI-24). The emphasis on recycling and reclamation is in
keeping with the current ecological perspective generated by deteriorating
environmental quality, energy shortages, and inefficient use of resources.
In addition to its research, the Federal government is prepared to fund much
of the capital expense of a land treatment disposal system. The Federal
Water Pollution Control Act Amendments of 1972 (PL 92-500) authorizes a
multi-billion dollar program to assist communities with 75 percent Federally
funded grants for constructing sewage treatment facilities. Included in the
facilities eligible for funding is the land required in land treatment
disposal systems (Ref. VI-28).
- 106 -
-------
Waste Characteristics
The characteristics of wastewater important to sludge recycling are
those components and concentrations which improve or harm the soil-plant
ecosystem. As discussed earlier, the nitrogen, phosphorus, potassium, and
organic matter content of wastewater sludges are desirable components for
soil conditioning and plant production.
The utility or toxicity of the various components of sludges is largely
a function of those concentrations found in the sludge, those concentra-
tions already in the soil, plant needs, and the physical-chemical-
biological characteristics of the soil and not inherent to the component.
For example, high application rates of sludge can lead to excessive
quantities of available nitrogen and subsequent crop injury and possible
pollution of the ground water with nitrates. Under the same high applica-
tion rates, soils would be expected to have little problem immobilizing
the heavy metals even under increased loading conditions. Moreover, plants
require some heavy metals in order to complete their growth cycle.
In general, those sludge characteristics which are beneficial to
sludge recycling are:
nitrogen content
phosphorus content
potassium content
organic matter content
* pH >6.0
• water and trace metal supplement
Most liquid and dewatered wastewater sludge contain these components at
levels high enough for crop application. The risk components of waste-
water sludges are the toxic metals and organics.
Operational Characteristics
Wastewater sludges can be applied to agricultural land in a liquid or
dried condition. Liquid sludges are sprayed onto the land surface or
injected into the soil using available farm equipment. Dried sludges can
be used for both fertilizing and soil conditioning purposes. The sludge
cake is dumped onto the land surface and is subsequently mixed with the
soil by disking. If soil conditioning is the primary intent, the sludge
cake (or compost) is usually pre-shredded befor application (Ref. VI-29).
In general, dried sludges require more handling than liquid sludges and may
require supplemental irrigation.
- 107 -
-------
Application rates of sludges to cropland vary according to the
nutrient requirements of the crop, existing soil characteristics (e.g.,
drainage, nutrient levels, heavy metal content, etc.), climate, and the
characteristics of the sludge. In all cases, the application rate should
be such that (1) crop production and quality are not decreased; (2) the
soil does not build up excessive organic material or heavy metals; and
(3) nutrients and excessive salts do not leak into surface or subsurface
water supplies. A range of application rate values may be stated as a
function of a particular physical parameter. However, because an applica-
tion rate depends on several physical parameters inherent to a given geo-
graphical situation, rates specified in relation to a particular parameter,
such as the following, should be viewed with caution. In applying liquid
sludge on relatively nonpermeable soils, an upper limit of 46.8 cu m/day/ha
(5,000 gal/day/acre) indicates, for applications not limited by heavy metals
content of the sludge, a maximum application rate (Ref. VI-30, VI-31, and
VI-32). To apply solid sludge, a maximum rate of 22.4 dry metric tons/yr/ha
(10 dry tons/yr/acre) can be considered as a safe long-term rate (Ref.
VI-33). In several cases a limit of 44.8 dry metric tons/ha (20 dry tons/
acre) (Ref. VI-33, VI-34, and VI-35) may be used, or in other cases soil
and sludge character may restrict the rate to only a few tons per year per
acre (Ref. VI-36). Based on broad climatic criteria, a general application
rate of 11-22 metric tons (12-24 short tons) of solids (dry weight) per
5000 sq m (6000 sq yd) per year has been found for humid regions (Ref.
VI-37). An equation (Eqn. I) determining the maximum levels of sludge
application for protection of cropland resources has been proposed by the
U. S. Environmental Protection Agency. The equation serves as a guideline
for soils that can be adjusted and held at a pH of 6.5 or greater for a
period of at least two years after sludge application.
Equation I (Ref. VI-38);
„,,.,, j /, ,. / N 32,600 x CEC
Total sludge (dry wt. tons/acre) = - r—z—-, ~z~~\—:—;—7 rrrc v^TT
6 J ' ppm Zn + 2 (ppm Cu) + 4 (ppm Ni) - 300
where: CEC = cation exchange capacity of the unsludged soil
in meq/100 g.
ppm = mg/kg dry wt of sludge.
This equation limits the heavy metal additions calculated as zinc
equivalent to ten percent of the CEC. The zinc equivalent takes into account
the greater plant toxicities of copper and nickel.
Sludge having a cadmium content greater than one percent of its zinc
content should not be applied to cropland except under the conditions
presented below.
(1) The land areas to receive such sludge are clearly identified in
the grant application.
- 108 -
-------
(2) There is an abatement program to reduce the quantities of cadmium
in the sludge to an acceptable level.
(3) The project is reviewed by the U. S. Department of Agriculture
and the Food and Jrug Administration.
jiting/Environmental Considerations
The following is a list of site selection criteria for a sludge
recycling program.
(1) Available Land - Sufficient producing or potentially productive
agricultural land should exist within a reasonable distance of
the sludge producer. A reasonable distance is defined by several
factors including quantities of sludge produced and cost of
transportation. The candidate sites should be composed of con-
tiguous farmland in order to minimize monitoring and distribution
costs.
(2) Public Acceptability - The populace that is expected to utilize
the sludge must be made aware of all operational and environmental
aspects of sludge recycling. Subsequently, there must be a good
economic basis for their initial and continued acceptance of the
method. Failing to provide for either of these needs could lead
to abrupt termination of the disposal program.
(3) Climate - During the cold season, provisions must be made to store
sludges until application is possible during the growing season.
Depending on the lengths of these periods, storage costs and
required acreage can be a problem. Precipitation and evapotrans-
piration during sludge application can present operational diffi-
culties. For example, sludge recycling in arid regions will
usually require supplemental irrigation. Humid regions will re-
quire reduced application rates and techniques which will reduce
the potential for excessive leaching of nutrients and salts.
(4) Accessibility - Candidate sites should be accessible by dependable
and economic transportation such as highways, pipeline, barge, or
-rail.
(5) Application Rates - Candidate sites should be able to utilize
reasonable quantities of sludge in order to minimize acreage
requirements and distribution costs. Application rates will
depend upon climate, existing soil characteristics (e.g., pH,
organic material content, nutrient availability, heavy metal
content, etc.), types of crops grown, and sludge characteristics.
(6) Pollution Potential - Candidate sites should be amenable to long-
term sludge application. Operational design of the system and
- 109 -
-------
the natural character of the sites should minimize any dele-
terious impacts of sludges on soil quality, plant growth, surface
runoff, and groundwater quality. This includes trapping and
treating runoff from agricultural lands.
Sludge recycling principally impacts three segments of the agricultural
ecosystem: (1) the soil; (2) the crops grown, both quantitatively and
qualitatively; and (3) the drainage water quality. The constituents of
sludge which have particular impact on these areas are the organic matter,
nutrients, and heavy metal concentrations. The interactions of these
sludge constituents with the land ecosystem create a complex system of
interrelationships and subsequent effects of which only the most important
will be discussed herein.
The organic matter in sludges is generally considered a valuable part
of the sludge composition for sludge recycling. Organic matter provides a
variety of beneficial effects to the soil system including: (1) increased
permeability, (2) friability, (3) increased water holding capacity,
(4) increased cation exchange capacity, and (6) adsorption of heavy metals.
The degradational rate of organic matter, however, varies according to the
type of sludge. Anaerobically digested sludges contain less-readily
degradable organic solids than undigested or aerobically digested sludges.
Consequently, anaerobically digested sludges cannot be applied at as high
a rate as undigested or aerobically digested sludges without organic matter
accumulating in the soil profile (Ref. VI-39). Excessive organic matter
accumulation can adversely affect ion solubility and availability, plant
growth, and drainage water quality (Ref. VI-39).
The nutrient concentrations of sludges, in particular those of
nitrogen and phosphorus, are important to crop production. The organic
nitrogen in sludges is released slowly and over a long period of time.
This is a desirable feature of sludge decomposition as it provides a rela-
tively constant long-term supply of nitrogen for plant assimilation and
provides a maximum impact of soil denitrification processes which helps to
eliminate excessive amounts of nitrogen in the soil (Ref. VI-40). However,
heavy applications of sludge on the land can result in excessive available
nitrogen which can result in crop damage and high nitrate concentrations in
surface runoff and subsurface drainage.
The phosphorus in sludges is largely precipitated as aluminum (Al),
iron (Fe), or calcium (Ca) phosphates. The phosphorus compounds are
sufficiently insoluble so that very little phosphorus would be expected
to leach into subsurface drainage. The capacity of soil to react with
phosphates is very great owing to the large quantities of Fe, Al, and Ca
present in most soils (Ref. VI-27 and VI-41). However, additions of large
quantities of phosphorus to soils can result in over-fertilization with
phosphorus, with subsequent crop damage and transport of phosphorus to
drainage waters (Ref. VI-27).
- 110 -
-------
Heavy metals, in particular Zn, Cu, Ni, and Cd, are added by sludge
application in quantities in excess of natural levels found in most soils.
These metals can, at relatively low available concentrations, render a soil
wholly unproductive. Fortunately, heavy metals are largely unavailable
for plant use and crop damage can be avoided with proper soil management.
Study results have shown that most heavy metals are far less available at
soil pH's above 6.5-7.0. Generally, a high organic matter content is
desirable for control of heavy metal availability. The presence of
phosphate and the cation exchange capacity of the soil also add to the
immobility of the heavy metals.
Many of the observations and points made above have to be considered
in both the short- and long-term operation of a sludge recycling program.
Probably the greatest short-term problem would result from excessive
application of sludge with subsequent break-through of nitrate and possibly
phosphate into drainage waters. In the long-term, the greatest problem has
to be the accumulation of heavy metals which could ultimately destroy the
productivity of a soil.
Plants which are grown at the sludge recycling site should possess the
characteristics of high nitrogen uptake, utility, and hardiness. Plants
with these properties serving as a cover crop include alfalfa, corn, and
general purpose forage grasses. Specific agricultural information for a
given area may be obtained from the local Agricultural Extension Service.
Because of similarities in methodologies of sludge recycle and land
reclamation, aspects of impacted resources will be discussed together here,
although land reclamation will be discussed in depth in the following major
section of this chapter. The main difference in methods is the primary
goal of sludge utilization. Land reclamation is primarily concerned with
sludge disposal, while land productivity and nutrient recycling are
secondary objectives. The principle goal of sludge recycle is to dispose
of sludge but coincidently to produce crops of economic value. The import
of this is that in land reclamation the effects of high concentrations of
toxic substances in the soil caused by large applications of sludge can be
tolerated until plant growth is inhibited or wildlife feeding on the vegeta-
tion are affected. Sludge recycle by agriculture is vitally concerned with
plant uptake of toxic substances because of the plants' eventual human con-
sumption.
Resources that are used or may be impacted by disposal/utilization of
residual waste (sludge) through sludge recycle and land reclamation include
the following:
(1) Water Quality - Effluent from sludge recycle/land reclamation
sites impact the following water-related resources:
(a) using the carrying capacity of subsurface waters receiving
leachates;
- Ill -
-------
(b) using the carrying capacity of surface waters receiving
surface runoff and groundwater-transported leachates;
(c) deterioration of subsurface and surface water supplies by
leachates;
(d) degradation of surface water supplies by surface runoff;
(e) chronic deterioration of ecological conditions in receiving
waters; and
(f) attenuation of erosion and surface runoff by growth of vegeta-
tion will improve surface water quality.
(2) Air Quality - Nocuous gas may be exposed and dissipated to the
atmosphere after sludge is spread. Such odors may affect
inhabitants of the surrounding area. When sludge is spread by
an aerial distribution system such as a sprinkler system,
aerosols, possibly containing pathogens, will be formed which
may be transported by winds to contact local residents.
(3) Land Quality - Possible impact upon land-related resources
includes:
(a) prevention of other surface land use by occupation of
surface area by the disposal facility;
(b) improvement of soil quality by adding organic and inorganic
nutrients;
(c) improvement of soil quality by conditioning soil,, thus
increasing humus content;
(d) clearing and regrading the land necessary for the landfill
may allow immediate erosion to occur;
(e) erosion caused by runoff resulting from application of
fluid sludge to land surface;
(f) land reclamation-mixing of sludge with surface materials (by
disking) may cause erosion by exposing a new barren surface
to weather elements, possible salt and toxic metal build-up;
(g) sludge recycle - physical manipulation of the soil for
agricultural purposes (e.g., plowing) may cause erosion by
exposing a new barren surface to weather elements;
(h) deposition of contaminants in soil by leaching beneath and
adjacent to the facility's perimeter;
- 112 -
-------
(i) land reclamation - prevention of erosion by presence of
vegetation promulgated by sludge application;
(j) sludge recycle - increased agricultural production;
(k) sludge recycle - provide supplemental irrigation; and
(1) land reclamation - neutralization of acid soil by applica-
tion of alkaline (lime) sludge.
(4) Aesthetics - Possible impact upon aesthetics includes:
(a) the presence of a sludge recycle facility may disrupt
existing land use composition of the adjacent area;
(b) odors generated by the facility may affect inhabitants of
the surrounding area;
(c) mechanical noise from the facility might annoy inhabitants
of the surrounding area; and
(d) the presence of vegetation allowed by sludge application may
be pleasing.
(5) Public Health - Possible impact upon public health considerations
includes:
(a) agricultural cultivation for direct or indirect human con-
sumption could produce crops that have incorporated toxic
substances in edible portions of the plant;
(b) the presence of toxic substances and pathogens in some
residual wastes might damage public health when pathogens
and/or toxic substances contaminate subsurface water supplies
or by lateral groundwater transport of leachates to surface
waters;
(c) direct surface runoff may contaminate surface water with
pathogens and/or toxic materials;
(d) vectors of pathogens (e.g., insects and rodents) may be
attracted to the site which could allow dissemination of
pathogens to populations in the surrounding area; and
(e) application of sludge by spraying will form aerosols
possibly containing pathogens. The aerosols may be wind-
blown from the site, contacting inhabitants of the adjacent
area.
- 113 -
-------
Specific Location Criteria
Important physical factors in predicting soil capacity for sludge
assimilation include soil structure, porosity, grain-size distribution, and
chemical characteristics. Because of the variety in soil types, some can
readily assimilate large amounts of particular sludges and other types can
assimilate only small amounts. While most soils are suitable for sludge
application, soils which are most likely to be unsuitable are (Ref. VI-42):
(1) extremely coarse-grained soils (coarse sands and gravel), (2) extremely
fine-textured soils (such as montmorillonite clays), (3) very shallow soils
(to water, bedrock, impermeable layers, or gravel), (4) wet, undrained
soils, (5) frozen soils, and (6) solonetz and other sodium-saturated soils.
Surface slope is an important factor in consideration of sludge appli-
cation rate because of water runoff or water ponding on the surface. While
ponding occurs on flat terrain where soils are either of low permeability
or are presaturated, water runoff generally increases with slope steepness.
In protecting surface waters from runoff contamination, Table VI-5 indicates
minimum distances of sludge application to water courses for sludge recy-
cling in Ontario, Canada. The processed organic sludge mentioned in
Table VI-5 has been stabilized by such means as anaerobic or aerobic
digestion. To protect groundwater resources, a minimum depth of 1.22 meters
(four feet) above high water tables or underlying rock is suggested
(Ref. VI-36).
TABLE VI-5
LOCATION OF SLUDGE APPLICATION BOUNDARIES IN ONTARIO, CANADA
Maximum
Sustained
Slope
Minimum Distance to Watercourse
For processed organic waste
application during May to
November inclusive
For processed organic waste
application during December
to April inclusive
0 to 3%
3 to 6%
6 to 9%
greater
than 9%
200 feet*
400 feet
600 feet
No processed organic waste
to be applied unless
special conditions exist
600 feet
600 feet
No processed organic waste
to be applied
No processed organic waste
to be applied
* one meter = 3.28 ft
Source: Ref. VI-43
- 114 -
-------
Suitability of Disposal
The suitability of municipal residual wastes for sludge recycling
depends primarily on three basic criteria: (1) operational considerations,
(2) institutional restraints, and (3) the needs of the crop and soil.
Table VI-6 compares a representative list of municipal residual wastes
with these evaluative criteria. The qualifiers of low, moderate, and high
are used for comparative purposes.
The primary operational consideration in sludge recycling is the ease
of application. Liquid sludges can be transported and distributed by pipe-
line and applied using conventional irrigation equipment. Dried sludges
require more handling and less efficient transportation methods.
Only a few states have regulations specific to wastewater or water
treatment sludge disposal on land (Ref. VI-29). The principle concern
with these wastes is that of public health and the degree of processing
required to destroy pathogens found in the wastes. In general, digestion
of the sludge is a minimum process requirement for use on any agricultural
land. Specific laws and regulations do exist which prohibit the use of
wastewater sludge on food crops that are eaten raw and on pasture land for
dairy cattle (Ref. VI-29).
The value of municipal residual wastes to crop production is largely
dependent on their nutrient (i.e., nitrogen, phosphorus, potassium, and
trace element) content and to a much lesser extent, their utility as a
soil conditioner. The soil conditioning value of the residual wastes is
largely a function of the organic matter content, as discussed earlier,
but can also include the beneficial effect of lime (i.e., calcium) on dis-
persed (i.e., sodium-rich) solids. All wastewater biologic sludges have
some nutrient and/or soil conditioning utility and calcium chemical sludge
may have some value as a soil conditioner. Sludge ash and alum sludges
have little utility for recycling because of their low nutrient content and
limited soil conditioning effects.
Management Agency Control and Monitoring^ Program
Control
A regulating agency may control disposal/utilization of sludge by
sludge recycle (also land reclamation) using a permit system, standards, and
land use regulations.
(1) General considerations of a permit system include:
(a) accurate description of proposed site;
(b) description of terrain alteration;
- 115 -
-------
TABLE VI-6
SUITABILITY OF VARIOUS MUNICIPAL WASTEWATER TREATMENT PLANT RESIDUAL
WASTES FOR SLUDGE RECYCLING/LAND RECLAMATION
Residual Wastes
Biological Treatment
Primary Sludges
Undigested
Thickened
Digested
Activated Sludges
Undigested
Thickened
Digested
Sludge Cake
Ash
Wet Oxidation
Incineration
Chemical Treatment
Alum sludge
Raw
Dewatered
Lime sludge
Raw
Dewatered
Operational
Constraints
None
None
None
None
None
None
Moderate
Moderate
Moderate
None
Moderate
None
Moderate
Institutional
Constraints
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
Nutrient
Content
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Low
Low
Low
Low
Low
Low
Soil
Conditioning
Benefits
High
High
High
High
High
High
High
Low
Low
Low
Low
Moderate
Moderate
- 116 -
-------
(c) existing and future land use of the surrounding area;
(d) projected use of the site after abandonment;
(e) environmenta1 impact survey;
(f) existence of water resources and present or potential use
of them;
(g) chemical, physical, biological properties of the waste and
possible pretreatment required;
(h) monitoring requirements (including levels of toxic sub-
stances in agricultural produce);
(i) general geologic character of the disposal site and adjacent
area including permeability and leaching properties of soil
and subsurface strata;
(j) highest probable annual groundwater table level and delinea-
tion of groundwater flow;
(k) documentation of need for disposal/utilization of sludge by
sludge recycle or land reclamation and discussion of disposal
alternatives and reasons for rejection;
(1) description of the process that produces the waste;
(m) controls to mitigate erosion and surface runoff;
(n) inhibition of vector presence;
(o) provision for storage, disposal, or utilization of sludge
during periods when sludge cannot be acceptably spread on
land, e.g., frozen ground, saturated soil;
(p) plan for dispension of agricultural produce; and
(q) attenuation of wind-(aerosol)transported pathogens.
(2) Applicable standards controlling disposal/utilization of sludge
by sludge recycle/land reclamation concern pretreatment and sub-
surface and surface receiving waters which may be directly con-
taminated by leaches. Characteristics of regulating these
receiving waters include:
(a) groundwater quality standards are usually broad, based on
public health criteria; and
- 117 -
-------
(b) surface water quality is usually regulated by well-defined
effluent discharge and receiving water quality standards.
Surface receiving waters may be directly susceptible to
pollution by erosion from the site or indirectly by
groundwater transport of leachates.
Pretreatment standards (that may be associated with permit
requirements) are usually well defined. Pretreatment standards
are particularly stringent regarding moisture content of input
sludge.
Additional standards especially pertinent to sludge recycle
methodology deal with control of toxic substances in agricultural
produce for eventual human consumption and regulation of pathogens
at the facility, e.g., pathogens carried in aerosols.
General considerations of standards (pretreatment and
receiving environment) include:
(a) quantity and rate of waste disposed at the site;
(b) toxicity of waste input and/or in receiving waters;
(c) number of pathogens in waste input and/or in receiving
waters;
(d) bionutrients from waste in receiving waters; and
(e) toxic substances in vegetation grown on site.
(3) General considerations of land use regulation concerning disposal/
utilization of sludge by sludge recycle/land reclamation include:
(a) existing land use/zoning of sludge recycle site (this is a
particularly significant consideration because land area
requirements are usually high). This type of control is not
generally applicable to land reclamation because of the
land's existing poor condition being virtually of no benefi-
cial use;
(b) because of erosion potential, regulations may constrain
the location of a sludge recycle site in the interests of
soil conservation;
(c) preclusion of future alternatives to land use at the site
due to the large amount of committed area and build-up of
toxic substances in soil; and
(d) use of land requiring the spreading of sludge may be con-
strained by public health regulations.
- 118 -
-------
Monitoring
Monitoring the effects of sludges on the land ecosystem will be a
necessary part of the management of the sludge recycling program. Because
of the paucity of quantitative data relating to sludge application experi-
ences and the always unique blend of soil, climate, crop, and sludge which
will exist for every program, monitoring of the recycle program will serve
several functions, the principal ones being research, operational
characterization, and environmental protection. The monitoring program
should include soil, plant, and groundwater analyses.
The objectives of soil analysis monitoring are to prevent toxic com-
pounds in the soil from building up to the point where damage is done to
crop production and drainage waters become contaminated. The biggest
difficulty in using this technique is measuring the existing levels of a
given ion in its plant available form. Currently, only a few techniques
are known for some ions in some soil regions which measure the amount of
available ion present (Ref. VI-44). Until research develops the necessary
techniques, soil analyses should monitor such critical soil factors as pH,
organic matter content, and total quantity and individual species of heavy
metals and other critical ions.
The plant is the final arbitrator of the impact of sludge recycling
on the soil. Such factors as nutrient mobility, nutrient solubility,
placement and site of antry into the plant, and translocation within the
plant are all indicated in plant composition (Ref. VI-44). Standard
analytical methods for plant analyses currently exist which can be applied
nationally. Plant analysis requires that the normal composition of the
indicator plant be known along with the upper tolerance levels for the
various toxic substances. Average composition levels of heavy metals for
selected food crops are shown in Table VI-7 along with suggested tolerance
levels. (It should be noted that these values are not necessarily endorsed
by EPA.)
The effect of groundwater monitoring is to evaluate the operation of
the sludge recycling program. Groundwater sampling should be done monthly
over a period of several months prior to sludge application in order to
provide adequate background data for comparative purposes. Monitoring
wells should be located within the site, up-groundwater gradient from the
site, and down-groundwater gradient from the site. Water samples should
be collected within two to three weeks after sludge application and at the
end of the growing season. Background water samples should be analyzed
for the following parameters:
(1) Chloride
(2) Specific conductance
(3) PH
- 119 -
-------
TABLE VI-7
THE PROBABLE AVAILABLE FORM, THE AVERAGE COMPOSITION RANGE FOR SELECTED
AGRONOMIC CROPS. AND THE SUGGESTED, TOLERANCE LEVEL OF HEAVY
METALS IN AGRONOMIC CROPS WHEN USED FOR MONITORING PURPOSES
Heavy Metal
Cations
Barium
Cadmium
Cobalt
Copper
Iron
Manganese
Mercury
Lithium
Nickel
Lead
Strontlaa
Zinc
Anions
Arsenic
Boron
Chromium
Fluorine
Iodine
Molybdenum
Selenium
Vanadium
Probable
Available
Fora
*£
CC
c°£
Cu£
Fe£
*£
Hg£
LC
NC
pi£
sr£
Zn^
AsO~
HBO~~
CrO~
F~
I
MoO~
Seo~~
vo-
Common Average
Composition
Range*
ppm
10-100
0.05-0.20
0.01-0.30
3-40
20-300
15-150
0.001-0.01
0.2-1.0
0.1-1.0
0.1-5.0
10-30
15-150
0.01-1.0
7-75
0.1-0.5
1-5
0.1-0.5
0.2-1.0
0.05-2.0
0.1-1.0
Suggested
Tolerance
Level**
ppm
200
3
5
150
750
300
0..04
5
3
10
50
300
2
150
2
10
1
3
3
2
* Average values for corn, soybeans, alfalfa, red clover, wheat, oats,
barley, and grasses grown under normal soil conditions. Greenhouse,
both soil and solution, values omitted.
* Values are for corn leaves at or opposite and below ear level at
tassel stage, soybeans - the youngest mature leaves and petioles on
the plant after first pod formation, legumes - upper stem currings
in early flower stage, cereals - the whole plants at boot stage, and
grasses - whole plants at early hay cutting stage.
Source: Ref. VI-44
- 120 -
-------
(4) Total hardness
(5) Alkalinity
(6) (a) Ammonia - uitrogen
(b) Nitrate - nitrogen
(c) Nitrite - nitrogen
(7) Total phosphorus
(8) COD
(9) BOD
(10) Heavy metals found in sludges applied
Routine water samples taken during the operation of the sludge recycling
program may be analyzed for only chlorides and specific conductance using
them as indicators of groundwater quality change (Ref. VI-44). Full
analysis would be required if these indicators deviated significantly from
the background level.
To enforce regulations governing disposal/utilization of sludge by
sludge recycle (also land reclamation, which is discussed in detail at a
later point in this report), general aspects of a monitoring program
during operation and after abandonment include:
(1) delineation of the presence and directions of subsurface
dispersion of waste constituents;
(2) surveillance of odorous gas produced at the site;
(3) detection of leachates transported to surface water;
(A) delineation of the amount and severity of surface erosion
and runoff to surface waters;
(5) seasonal variation in groundwater depth and direction of
movemen t;
(6) deposition of toxic substances in soil;
(7) incorporation of toxic substances in vegetation grown on
site; and
(8) pathogens carried off the site.
- 121 -
-------
Costs of Sludge Recycling
Owing to the difference in location between the sludge source and
application site, cost of sludge transport is an important factor, aside
from the actual cost of application, in considering sludge recycling as a
method of ultimate disposal. Figures VI-2, VI-3, and VI-4 show estimated
comparative costs of sludge disposal by alternate means of cities of
populations of 10,000; 100,000; and 1,000,000, respectively (Ref. VI-14).
Table VI-8 indicates costs (updated to 1975) of sludge recycling at various
sites in the United States. For undigested liquid sludge, costs (updated
to 1975) vary between $8 and $57 per ton of dry solids with an average
cost of about $19 per ton (Ref. VI-12). With the inclusion of capital
and operating cost for anaerobic digestion the range increases to $15
to $95 per ton with an average of $29 per ton. The cost of land in o.
given area is, of course, an important constituent cost whether the land ;
is bought out-right or leased. General land costs are presented in the
section of this report concerning landfills. While the harvest of surface
cover (crops) will to some degree offset application costs, a survey cf
community sludge disposal in northwestern Ohio (Ref. VI-36) indicated no
return on crop sales, primarily due to emphasis on sludge disposal rather
than gaining a resource return through crop sales.
TABLE VI-8
COSTS FOR LAND SPREADING DIGESTED SLUDGE
Location
Chicago, Illinois
San Diego, California
Piqua, Ohio
St. Marys, Pennsylvania
Approximate
Plant Size
(mgd)
1300
90
3.8
1.3
Cost
($/ron)a
75.98 = Current
44.23 = Ultimateb
13.27
21.96 - 37.65
25.00
Excludes digestion and costs are given per ton of digested
solids updated to 1975.
Ultimate costs include pipeline to be constructed. A
principle variable is transportation cost.
Source: Ref. VI-45
- 122 -
-------
LAND RECLAMATION
Introduction
The nutrient content ;.nd soil conditioning properties of many
wastewater including chemical sludges can be utilized to build up
marginally productive soils or reclaim nonproductive soils such as those
derived from strip-mining operations. Approximately 1200 sq km (296,400
acres) of land in the United States have been used by coal strip-mining
operations, with an additional 120 sq km (29,640 acres) being added
annually to this total (Ref. VI-46). Strip mining generally degrades the
water quality, aquatic environment, and riparian wildlife habitat by
removing existing vegetation and topsoil, altering the surface drainage,
and exposing fresh bedrock material which is unsuitable for plant growth
(Ref. VI-46 and VI-47). Attempts to reclaim such sites by revegetation
have been few and limited to Federal and State agencies, owing mostly to
high capital costs (Ref. VI-46). As a result, large tracts of land exist
which offer a potential for combined sludge disposal and land reclamation
programs.
The objectives of a land reclamation program utilizing sludges differ
from those of sludge recycling primarily in priority (Ref. VI-44).
Whereas a sludge recycling program is limited by the usefulness of the
sludge properties for crop production, land reclamation is concerned pri-
marily with sludge disposal, with crop production and nutrient recycling
being secondary objectives. In general, projected uses of reclaimed land
are undefined but can be assumed to be some form of recreational, resi-
dential, commercial, and/or industrial use and not food production
(Ref. VI-44). However, in the case of the Metropolitan Sanitary District
of Greater Chicago, land reclamation of strip-mined areas is seen as a pre-
liminary step in a long-term sludge recycling program which includes the
production of food crops (Ref. VI-21).
Some of the advantages offered by land reclamation are given below.
(1) Large quantities of sludge can be disposed of per unit of land.
(2) A large variety of sludges or even mixtures of sludges can
often be used.
(3) A land reclamation program can be operated year-round if the
climate allows.
(4) At the end of sludge application, previously barren land will
have more potential land uses.
(5) Land reclamation will improve surface water quality by controlling
erosion and runoff, and upgrading existing soil characteristics.
- 123 -
-------
Some of the disadvantages of land reclamation are given below.
(1) There are considerable site preparation costs.
(2) The operator-owner of the site becomes responsible for site
runoff quality.
(3) The long-term effects of sludge application are still uncertain,
especially in terms of heavy metal build-up and soil toxicity.
(4) Chemical sludges will require fertilizer enrichment in order to
support vegetation.
Many of the operational and environmental considerations/mechanisms
of sludge recycling are applicable to land reclamation utilizing sludges.
The primary differences are related to the projected uses of the land
being used. For land designated for uses other than food production, the
effects of high concentrations of toxic metals in the soil, caused by
large applications of sludge, can be tolerated until plant growth is impeded
or wildlife feeding on the vegetation are affected (Ref. VI-44) .
Waste Characteristics
The desirable characteristics of sludges for land reclamation are
identical to those discussed under sludge recycling (see SLUDGE
RECYCLING - Waste Characteristics of this chapter). However, in the case
of strip-mined areas, the low pH of the soil is such a dominant factor
prohibiting plant growth that improvements in soil pH are essential for
plant growth. Coal strip-mine spoil contains pyrite (FeS) which oxidizes
in the top, aerated layers to ferric hydroxide [FeCOH)^] and sulfuric acid
(l^SO^). This causes the pH of the soil to be as low as two or three in
many cases (Ref. VI-A6 and VI-47). Most plants require soil pH's greater
than those in order to survive. The addition of lime sludges generated by
wastewater processes would aid in neutralizing the acid characteristics of
the oxidized zone0
Operational Characteristics
Potential land reclamation sites will normally require extensive site
preparation before disposal can begin. In the case of strip-mined areas,
the land is highly irregular and must be leveled before use. In general,
land reclamation programs require a closed system to prevent surface runoff
from entering streams before sampling can be completed to assure that the
runoff meets stream water quality standards (Ref. VI-48). This means that the
construction of such structures as berms, dikes, and holding basins in
addition to general regrading adds significantly to the cost of the program.
Digested liquid sludges appear to be an optimum sludge form for
several reasons. Soil amelioration is best accomplished by thorough mix-
ing of the sludge and spoil (or soil) material (Ref. VI-47). Mixing can
- 124 -
-------
be more easily and effectively achieved by the infiltration of the liquid
sludge. The use of dewatered sludges would require extensive disking and
supplemental irrigation in order to achieve similar results. Also, large
volumes of liquid sludge can be applied using irrigation equipment and
technology at a much lowe" operating cost than dewatered sludges. A
digested sludge or stored sludge for 60-90 days would have far fewer
pathogenic bacteria than an undigested sludge. This is an important factor
when considering site runoff quality. A digested liquid sludge also has
the advantage of not requiring expensive solids handling processes at the
wastewater treatment plant.
Sludge application procedures are similar to those used in wastewater
spray irrigation programs. Each site will be operated at an optimum
application rate based largely on the infiltration capacity of the soil.
Allowances will be made (in the form of intermittent operation) for soil
drainage and normal precipitation, the primary objective being to minimize
surface runoff. A reasonable range for loading rates would be from 4500 to
22,400 metric tons of dry solids per sq km per year (20 short tons to 100
short tons/acre/year) (Ref. VI-21 and VI-47). The Metropolitan Denver
Sewage Disposal District No. 1 (Ref. Vl-45) disposes 16-percent solids
sludge cake on a bombing range at a rate less than or equal to 0.09 metric
tons/sq km (25 dry tons per acre). This sludge is a conditioned mixture of
raw primary sludge, anaerobically digested primary sludge, and aerobically
digested excess activated sludge. Another specific case of land reclama-
tion is in Illinois where the Metropolitan Sanitary District of Greater
Chicago (Ref. VI-45) is applying digested sludge to strip mines at a
decreasing rate from an initial 68 metric tons/acre/year (75 dry tons/acre/
year) to 18 metric tons/acre/year (20 dry tons/acre/year) over a five-year
period.
Periodic disking of the site prior to and during sludge application
will be necessary to increase infiltration and deepen the zone of mixing.
For strip-mine spoil, a mixing (plow) depth of 25 cm (10 in.) from the land
surface is desirable in order to neutralize this most active (i.e., acid-
producing) zone (Ref. VI-47). Seeding of the site should be done as soon
as is reasonable after sludge application in order to reduce surface runoff
and erosion.
Siting/Environmental Considerations
The following is a representative list of site selection criteria for
a land reclamation program utilizing sludges.
(1) Available Land - Sufficient (i.e., enough acreage to handle long-
term quantities of sludge) nonproductive land should exist within
a reasonable distance of the sludge producer. A reasonable dis-
tance is defined by several factors including quantities of
sludge produced and cost of transportation. The candidate sites
should be composed of contiguous areas, preferably within a
- 125 -
-------
minimum number of watersheds, in order to minimize land
preparation, monitoring, and operating costs.
(2) Public Acceptability - The populace of the region should be made
aware of all operational and environmental aspects of land recla-
mation utilizing sludges. Subsequently, there must be a favorable
economic basis and reasonable compatibility with local land use
planning objectives in order to insure continued acceptance of
the program.
(3) Condition of Land - The candidate site topography cannot be so
irregular that site preparation costs become excessive.
(4) Accessibility - Candidate sites should be accessible by depend-
able and economical transportation such as highways, pipelines,
barge, or rail.
(5) Pollution Potential - Candidate sites should be amenable to long-
term sludge application. The operational design of the system
and the natural character of the sites should not only minimize
any deleterious impacts of sludges, but improve soil quality,
plant growth, surface runoff, and groundwater conditions.
Because land reclamation generally involves considerable recontouring
of the land in order to control and minimize surface runoff, one of the
initial impacts of the program will be the altering of the basin hydrology.
In fact, most of the effects of the program, such as increasing soil pro-
ductivity, and subsequently, vegetation cover, lead to changes in the basin
hydrology. Increased vegetation cover along with recontouring reduces
erosion and surface runoff. The additional water from the sludges results
in greater groundwater recharge and subsequent increases in stream base-
flows and watertable elevations. Evapotranspiration will be increased
within the basin owing to increases in vegetative consumption and soil and
water retention properties. Ultimately, the long-term impact of land
reclamation, if managed properly, should result in a general improvement
of the hydraulic and water quality characteristics of a basin.
Land reclamation, once it has passed the point where productive top-
soil is produced, can be expected to have environmental impacts similar to
those found in sludge recycling, which have been discussed earlier.
Suitability of Disposal
The suitability of municipal residual wastes for land reclamation
follows much the same lines of reasoning discussed previously under sludge
recycling (also see Table VI-6). In addition, the value of chemical
sludges (in particular lime sludges) as a soil aid, especially in raising
soil pH in strip-mine waste, is significantly increased.
- 126 -
-------
Management Agency Control and Monitoring Program
The control program elements for land application of municipal
residual wastes would be the same as those previously mentioned for sludge
recycling.
The monitoring program for land reclamation should include soil,
plant, groundwater, and surface water analyses. Except for surface water
monitoring, which may be optional in sludge recycling programs, the nu_nitor-
ing provisions for land reclamation are identical to those for sludge recy-
cling. Surface water monitoring for land reclamation can be expected to be
a regulatory requirement because of the high rates of sludge application.
Surface water runoff will be a controlled feature of the land reclama-
tion project and will not be released to open streams before it is analyzed
and found to meet required stream standards. Parameters to be analyzed
should include:
(1) Fecal coliforms
(2) pH
(3) Chlorides
(4) Alkalinity
(5) Specific conductance
(6) (a) Ammonia nitrogen
(b) Nitrate-nitrogen
(c) Nitrite-nitrogen
(7) Total phosphate
(8) COD
(9) Heavy metals found in applied sludges
(10) Turbidity
Costs of Land Reclamation
The following two land reclamation cases described in regard to sludge
application rates serve as examples of land reclamation costs. In applying
up to 0.09 metric ton/sq km (25 dry tons of sludge per acre), the Metro-
politan Denver Sewage Disposal District No. 1 (Ref. VI-45) has incurred a
cost (updated to 1975) of $56 to $69 per ton. The Metropolitan Sanitary
- 127 -
-------
District of Greater Chicago (Ref. VI-45) has found the cost (updated to
1975) of preparing strip-mined land for sludge disposal to range from
$2300 to $3500 per acre. Using barge transportation (1973) at $36.81 per
ton, the total cost of disposal is $71.54 per ton of solids. Once pipeline
transport is implemented, the total cost (1973) of sludge disposal is
expected to be $35.24 per ton of solids. These totals include sludge
digestion at $9.22/ton.
OCEAN DISPOSAL
Introduction
Ocean disposal of residual wastes is a form of ultimate disposal which
exploits the ocean's large dilution capacity to alleviate possible detri-
mental effects of the waste upon sustained use of land-related resources.
Thus, because of its size and mixing properties, the ocean may be, under
properly engineered conditions, a convenient dumping place for various
types of waste materials. In 1968, approximately 43 million metric tons
(48 million short tons) of waste (U. S.) were discharged to the ocean.
Included in this figure are 34 million metric tons (38 million short tons)
of dredge spoil, 4.1 million metric tons (4.5 million short tons) of
industrial wastes, 4.1 million metric tons (4.5 million short tons) of
sewage sludges, and 0.5 million metric tons (0.5 million short tons) of
construction and demolition debris (Ref. VI-49). In 1972, the amount of
waste discharged into the oceans increased from 43 million metric tons
(48 million short tons) to 47 million metric tons (52 million short tons).
Ocean quality is a relatively new concern in the development of
environmental protection. Previously there existed few direct legal con-
trols regulating ocean disposal of residual wastes. Legislative efforts
were primarily aimed at controlling oil pollution and the effect of pollu-
tion from exploration and exploitation of natural resources. In 1970, the
Council on Environmental Quality presented a report entitled "Ocean Dump-
ing - A National Policy" (Ref. VI-50) which stated:
Ocean dumping of undigested sewage sludge should be halted as
soon as possible with no new sources allowed.
Ocean dumping of digested or other stabilized sludge should be
gradually stopped with no new sources allowed. Where substantial
facilities and/or significant commitments exist, continued ocean
dumping may be necessary until alternatives can be developed and
implemented. Continued ocean dumping should be considered an
interim measure.
In accordance with the report recommendations, Environmental Protection
Agency guidelines were issued in 1971 which greatly inhibited use of the
ocean as a site of ultimate disposal. During September 1972, the
- 128 -
-------
President's Water Pollution Control Advisory Board issued a report, "Ocean
Disposal Practices and Effects" (Ref. VI-51), which concludes that the
presence of toxic materials, primarily the heavy metals, in municipal
sewage can cause particular problems in the ultimate disposal of waste-
water treatment sludge. There materials may have a harmful effect due to
their possible entry into the marine food chain when ultimate disposal of
sludge is to the ocean.
In October 1972, Congress passed the Marine Protection. Research, and
Sanctuaries Act (Ocean Dumping Act). The purpose of this legislation is
to regulate the carriage of substances from the United States for dumping
into ocean waters. Substances are defined to include sewage sludge. Thus,
in addition to the Water Pollution Control Act of 1972 (which covers all
outfalls into marine waters as well as all types of discharges into the
territorial sea) the Ocean Dumping Act covers all dumping in the U. S.
ocean waters of the territorial sea and the contiguous zone. EPA guidelines
promulgated by the Ocean Dumping Act (Ref. VI-52) were issued in October
1973 and impose stringent regulations and criteria upon ocean dumping.
However, the EPA has published regulations (Ref. VI-53) describing pro-
cedures for application for, and issuance and denial of, permits for ocean
dumping.
Waste Characteristics
Both wastewater and water treatment sludges can be disposed to the
ocean. If the sludge can be pumped, then it may be discharged by barge or
submerged outfall. The barge may be equipped with drop doors to dump
thicker sludge. In general, flotable solids must be minimized due to the
solids concentration at the surface. This is because only areal dispersion
exists near the surface rather than three-dimensional dispersion which
takes advantage of the ocean site volume.
The "Final Regulations and Criteria" for ocean dumping issued by EPA
(Ref. VI-52) defines prohibited waste characteristics and materials
requiring special care. Table VI-9 indicates a selection of prohibited
wastes that apply to wastewater residual wastes from the EPA guidelines.
Operational Characteristics
Waste disposal to the sea is primarily by either a submerged outfall
(pipeline) or by surface/near-surface dumping (barge). By ocean outfall,
municipal wastewater sludge may be piped many miles to be discharged
(usually) through a section of diffuser conduit several feet above the
bottom. Typical operation is fairly simple, consisting of monitoring and
maintenance of the pump, pipeline, and diffuser. Depending on operation
of the solids removal process and resulting effluent concentration, active
regulation of pump rate may be necessary. When sludge production is small
enough to permit intermittent operation, the outfall may require flushing
with fresh or reclaimed water after each discharge period to prevent sedi-
mentation and possible clogging of the diffuser.
- 129 -
-------
TABLE VI-9
A SELECTION OF PROHIBITED WASTES THAT APPLY TO WASTEWATER
TREATMENT PLA1.I RESIDUAL WASTES FOR OCEAN DISPOSAL
Degree of Prohibition
Materials/Constituents
Complete
3.
Materials insufficiently described in
terms of chemical, and biological proper-
ties to evaluate in terms of environment-
al impact.
Inert materials which float or remain in
suspension.
Biological agents capable of infesting,
infecting or altering the normal popula-
tions of organisms, degrade uninfected
areas, or introduce species not
indigenous to an area.
Prohibited by exceed-
ing defined amounts
1. Mercury:
2. Cadmium;
solid material
liquid material
solid material
liquid material
0.75 mg/kg
1.5 mg/kg
0.6
3.0
mg/kg
mg/kg
3. Oil and Grease: must be of consistency
so that a visible surface sheen will not
be produced in a quiesent water sample
when added at a rate of one part water to
100 parts water.
Source: Ref. VI-52
Physical requirements of barging wastes to sea include shore
facilities (collection systems, pumps, pipelines, storage tanks, and barge
loading equipment), at least one barge (towed or self-propelled), and a
dump site. Operation basically consists of first loading the barge by
pump or gravity flow from storage tanks and then transporting the barge to
the dumping area, usually by a specified time table. Once at the site,
several runs are made within the area so all the waste is not released at
one point. Sludge within the barge is discharged by pump or gravity flow
usually into the wake to aid dispersion of the effluent. The cargo
- 130 -
-------
compartments may be flushed out depending on the sticky and gritty
qualities of the sludge. During rough weather, the barge may not travel at
all, thus requiring storage on shore, or waste may be transported in smaller
quantities than normal.
Siting/Environmental Considerations
Prerequisite to a decision regarding the environmental feasibility of
ocean disposal, a preliminary investigation of environmental conditions at
potential discharge sites must be made.
Opportunities for affecting environmental quality by waste discharges
include possible spills on shore and during transport as well as discharge
at the site. With proper care in design, construction, operation, and
maintenance, accidental spills can be minimized and are usually insignifi-
cant compared to the volume of waste discharged at the disposal area.
Environmental effects of accidental discharges will probably be similar to
the main discharge with primary differences in magnitude.
Despite the differences between ocean disposal by submerged outfall
and surface dumping by barge (especially differences in depth and distance
from shore of the discharge), several common siting criteria based on
environmental effects exist and will be subsequently discussed. Since the
concept of ocean disposal is environmentally founded on dilution, one of
the most important criteria to be met is high dispersion characteristics
at the site. Dispersion of waste constituents is primarily due to advec-
tive flows (ocean currents). Both current flow magnitude and direction
must be considered in relation to location of ocean resources and discharge
point. These resources include protection of the shoreline and bottom from
waste deposition. Usually a sandy bottom condition is an indication of
bottom scouring caused by water currents, and such a condition is generally
sought. Other components of dispersion include eddy and molecular diffusion
within the water column. A deterrent to vertical mixing that may occur
during summer is the presence of a thermocline. By inhibiting vertical
mixing, waste constituents will remain in greater concentration for longer
periods of time.
Siting criteria more applicable to submerged outfalls are dependent
on water depth and proximity to shore. By discharging waste near the
bottom, rapid sedimentation of suspended solids will occur unless adequate
dispersion exists. Ideally, the waste should have low vertical dispersion
with great horizontal dispersion of suspended solids. Limited vertical
mixing will enhance light attenuation which inhibits surface and near
surface photosynthetic growth plus causing aesthetically displeasing murky
water. Ocean swells in relatively shallow water can cause much vertical
mixing, preventing sedimentation; therefore, discharge sites should be far
offshore beyond the breaker zone. To prevent deep deposits of solids near
the outfall which can adversely affect benthic organisms, the solids should
- 131 -
-------
be allowed to settle over as great an area as possible. The use of a
diffuser at the outfall will aid in greater distribution longitudinally on
the bottom and jet mixing from the diffuser ports will suspend the solids
enough to allow lateral dispersion over a greater area. Evidence of
potential solids transpor_ from the site is given by the presence of high
sand/low silt-clay composition of the bottom plus lower biomass and bio-
number (Ref. VI-54). This implies a greater degree of scouring of sedi-
ments important for most effective dispersion and subsequent transport
from the area.
The small amount of floatable solids in residual waste permitted for
ocean disposal must be dispersed widely by water currents before appearing
at the surface. In a similar manner, dissolved solids should be dispersed
as greatly as possible. This conflicts with limited vertical mixing
required of suspended solids which would cause greater waste concentration
near the bottom. Depending on the waste, trade-offs must be made in siting
conditions depending on the potential for adversely affecting ocean
resources such as human health, welfare and aesthetics; the marine environ-
ment, ecological systems, or economic potentialities; or plankton, fish,
shellfish, wildlife, shorelines, or beaches.
Siting criteria more applicable to surface discharge (from a barge)
is less constrained than a submerged outfall primarily because of being
discharged over a greater area and being further from shore. The dis-
persion conditions mentioned in connection with submerged outfalls is valid
when dealing with barging; but, because of being dumped at the surface,
subsequent settling deposition on the bottom is not as critical. However,
because components of the waste will sink to a density equilibrium point
providing a discrete cloud layer of potentially toxic water (Ref. VI-55),
surface and mid-depth mixing becomes more important. By discharging to
the surface, odor may also pose a problem if insufficient dispersion occurs.
Surface discharge can generally disturb the marine ecosystem because sur-
face and subsurface depths are particularly sensitive due to the presence
of photosynthetic organisms which comprise the first element of the marine
biological food chain. Toxins such as heavy metals may accumulate in higher
organisms, e.g., fish and shellfish, by ingestion to the point of causing
harmful physiological effects to these organisms.
Natural resources that are utilized or may be impacted by ocean
disposal of residual waste include the following:
(1) Water Quality - Ocean disposal primarily makes use of the
ocean's dilution capacity (a resource) to ameliorate nocuous
components of the disposed waste. Possible impact on. resources
includes:
(a) degradation of water supply (potential supply from
desalination);
- 132
-------
(b) chronic inhibition of particular biological elements in
the marine ecosystem;
(c) disruption of marine fisheries (fish, shellfish,
crustaceans);
(d) stimulation of particular biological elements in the
marine ecosystem; and
(e) degradation of recreational value, e.g., primary contact
such as swimming.
(2) Air Quality - Nocuous gases may be exposed and dissipated to the
atmosphere upon discharge. Possible impact on resources
includes the degradation of shoreline recreational and resi-
dential values.
(3) Land Quality - From the discharge point, waste components may be
transported and deposited on the beach which could be detri-
mental to indigents of the littoral zones and create a public
health problem to beach users. Solids from waste discharge may
impede navigation by channel siltation.
(4) Aesthetics - Ocean disposal of residuals may detract from the
aesthetic value of the sea and seashore by:
(a) causing waste floatables to exist at the surface;
(b) depositing waste components on the seashore; or
(c) generating nocuous odors.
(5) Public Health - The presence of toxic substances an,d pathogens
in some residual wastes might infringe upon public health when:
(a) pathogens are in primary contact with humans, e.g.,
swimming;
(b) pathogens infect marine organisms used for food; or
(c) toxic substances (e.g., heavy metals) are present in
marine organisms used as food.
Suitability of Disposal
Given a wastewater treatment plant residual waste to dispose of, the
immediate question arises as to its amenability to disposal by a particular
method. A list of representative wastes is presented in Table VI-10 along
- 133
-------
TABLE VI-10
SUITABILITY OF VARIOUS MUNICIPAL WASTEWATER TREATMENT
PLANT RESIDUAL WASTES FOR OCEAN DISPOSAL
Residual Waste
Biological Treatment
Primary Sludges
Undigested
Thickened
Digested
Activated Sludges
Undigested
Thickened
Digested
Sludge Cake
Ash
Wet Oxidation
Incineration
Chemical Treatment
Alum Sludge
Raw
Dewatered
Lime Sludge
Raw
Dewatered
Operational
Constraints
No
No
No
No
No
No
Yes
Yes
Yes
No
Yes
No
Yes
Institutional
Constraints
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Alteration
of Benthos
High
High
Moderate
Moderate
Moderate
Low
Moderate
Low
Low
Low
Moderate
Low
Moderate
Presence of
Significant
Toxics
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Low
Low
No
No
No
No
- 134 -
-------
with specific attributes of ocean disposal. The waste evaluation term for
each attribute category is based on both absolute and relative criteria.
The category of "operational constraints" in Table VI-10 is used to
evaluate various wastes bared on disposal alternatives allowed by the ease
with which the sludge can be pumped to a subsurface depth. Waste is pumped
to a point below the surface both from a barge (in addition to surface
dumping) and from a submerged outfall. Of the listed wastes in the table,
only those possessing a high percent of solids are constrained to non-
pumped discharge.
All means of ocean disposal are constrained by Federal government
regulations. These regulations are orientated toward waste constituents
rather than general waste types (Ref. VI-52). In addition, the disposal
site is also controlled by these regulations. Before an ocean discharge
permit is granted, the federal regulations must at least be met before
state regulations are considered.
The biological community (benthos) of the ocean floor may be affected
by ocean dumping of wastes. These effects include (aside from specific
toxics) physical deposition of solids on organisms and substrata causing
abrasion plus lower available dissolved oxygen due to the BOD of the
solids. Based on these two criteria, the listed wastes of Table VI-10
were evaluated in regard to relative alteration of the benthos.
While nearly any substance can be biologically toxic if present in
great enough quantity, wastewater treatment plant residual wastes may con-
tain materials which are toxic in relatively omall concentrations. These
materials include heavy metals, pesticides, and pathogens. In Table VI-10,
representative wastes are comparatively evaluated concerning their content
of significant toxics. Source controls, particularly for industrial inputs
to municipal wastewater treatment systems, should be employed to alleviate
the possible difficulties of using ocean disposal as a potential, viable
alternative.
Management Agency Control and Monitoring Program
Control
Control that a management agency may impose on ocean disposal of
residual waste can be exerted by means of a permit system, standards, and,
to a smaller degree, land use regulation.
(1) General considerations of a permit system include:
(a) specific designation of disposal site;
(b) predisposal environmental impact survey;
(c) quality standards of waste to be disposed;
- 135 -
-------
(d) quantity of waste to be disposed;
(e) frequency of waste disposal;
(f) monitoring requirements;
(g) documentation of need for ocean disposal and delineation
of disposal alternatives and reasons for rejection;
(h) conveyance of waste;
(i) description of disposal method;
(j) description of process that produces the waste; and
(k) contingency plan for barging when the ocean is too rough
for shipping.
(2) General considerations of standards (pretreatment and receiving
water) include:
(a) quantity of waste disposed in a specified area;
(b) toxicity of waste input and/or in receiving waters;
(c) number of pathogenic agents in waste input and/or in
receiving water;
(d) inert materials that float or will remain in suspension
contained in waste to be disposed;
(e) bionutrients of waste input and/or in receiving waters; and
(f) thermal character of waste input and/or in receiving waters.
(3) General considerations of land use control include:
(a) land use/zoning of shore facilities;
(b) land use/zoning of shoreline that may be affected; and
(c) zoning of affected ocean waters that may be allocated for
other uses, e.g., fisheries.
Monitoring
An ocean disposal monitoring program should include operational feed-
back as well as independent environmental investigations. During operation
of a submerged outfall, a record of sludge flow plus an indication of sludge
- 136 -
-------
quality should provide information on environmental impact given a thorough
preliminary investigation before operation and during "normal" operation.
Ocean disposal by surface discharge (barging) usually is operationally
documented by the ship's log book. It may contain the following informa-
tion: time of departure from shore, time of arrival at the site, location/
time/direction of each dumping run, wind and water conditions during each
run, and time of leaving site and arrival at port. Record of tank flushing
may also be included in the log.
In general, the same environmental monitoring can be applied to both
surface and submerged disposal. Given the characteristics of the waste,
those constituents of relatively high concentration which are specified as
"materials requiring special care" in EPA's regulations and criteria of
ocean dumping are ones which should be quantitatively analyzed from site
water samples. Water samples are taken from the "mixing zone" where area/
depth is defined in the federal regulations. Periodic monitoring might
typically include: (1) physical analysis-transparency, temperature, and
odor; (2) chemical analyses-chlorides, dissolved oxygen, biochemical
oxygen demand, organic nitrogen, nutrients, and total sulfides; (3) bio-
logical analyses-phytoplankton/zooplankton/coliform bacteria; and (4) ben-
thic analyses-lithology, organism numbers and species. Sampling sites
include particularly sensitive areas of protected resources, e.g., beach,
shellfish, fish nurseries, etc.
To enforce ocean disposal regulations, general aspects of a monitor-
ing program include:
(1) quality/quantity of waste through an ocean outfall;
(2) quality/quantity of waste and frequency of trips for barging
(dumping);
(3) for ocean dumping, the ship's log should contain time of
departure from shore, time of arrival at site, location/time/
direction of each dumping run, wind and water conditions during
each run, and time of leaving site and arrival at port;
(4) water and bottom quality at disposal site and in adjacent areas
of ocean use, e.g., beaches and fisheries; and
(5) shoreline surveillance for deposited flotsam and existence of
nocuous odors.
Costs of Ocean Disposal
The costs of ocean disposal can be presented by viewing ocean dumping
(barging) separate from disposal by ocean outfalls. The range of barging
costs (updated to 1975) along the Atlantic Coast is estimated (Ref. VI-56)
- 137 -
-------
to be $1.50 to $2.30 per ton. Burd (Ref. VI-12) presents several specific
cases of sludge barging costs. New York City incurs a total cost (updated
to 1975) of about $14.30 per ton of dry solids with an average round-trip
distance of 25 miles. The cost of ocean barging from Philadelphia (updated
to 1975) is $24.25 per ton of dry solids (wet sludge of 10-percent solids)
and $32.60 per ton of dry solids (wet sludge of five-percent solids).
Derr, et al (Ref. VI-53), estimate the total costs (updated to 1975) per
dry ton for ocean barging to be slightly over $0.20/mile. Figure VI-5
indicates barging costs to a site 80 miles offshore using one, two, or
three barges. The cost of an outfall is primarily dependent on the diam-
ete- and length of the pipeline. Figure VI-5 indicates estimated cost
(1970) of outfalls ($/ton dry solids) for five- and eighty-mile discharge
points. Burd (Ref. VI-12) states that operating cost (updated to 1975) at
the Los Angeles Hyperion plant is expected to be $2.20 per ton of dry
solids. Derr, et al (Ref. VI-53), estimate the total costs (updated to
1975) per dry ton for ocean outfalls to be $0.70/mile.
RESOURCE RECOVERY METHODS
Introduction
Wastewater treatment residual sludge is a valuable resource, generally
unexploited in direct use or in producing a marketable product. Biological
sludges may serve as a basic source of organic compounds and nutrient
elements while sludges from physical-chemical processes may be treated to
regenerate chemicals necessary to the wastewater or sludge treatment pro-
cess. In general, resource recovery is an attempt to maximize resource
utilization. Resource recovery has been relatively ignored due to lack of
suitable markets for directly utilized sludge or manufactured end products,
and the required high cost to convert sludge into a marketable product. A
product of monetary value would reduce the cost for sludge management.
When the cost for additional handling and processing of the sludge is less
than the monetary value received for the product, then the total cost for
sludge management will be reduced. The methods of resource recovery dis-
cussed in this section are:
(1) incineration;
(2) pyrolysis;
(3) lime recalcination;
(4) composting; and
(5) sludge recycle.
- 138 -
-------
FIGURE 21-5
COMPARATIVE ECONOMICS OF TRANSPORTING
DIGESTED SLUDGE FOR OCEAN DISPOSAL
o
V)
o
I-
09
o
o
cc
o
Q.
(O
o:
J-
<
o
35
30
25
20
15
10
I TANKER
BASIS: Sludge at 3.5% Solids
by Weight
TANKER DISPOSAL
TO EIGHTY MILES
OFFSHORE
3 TANKERS
80 MILE OUTFALL
200
400
600
800
1000
1200
THROUGHPUT, tons/day
SOURCE1 Reference 21-57
- 139 -
-------
Incineration
With adequate dewatering to approximately 30-percent solids,
incineration is usually self-sustaining without the need for supplemental
fuel. Table VI-11 is presented to indicate the general heat values of
various sludges which may be incinerated. The advantage of incinerating
undigested sludge can be noted in this table in that these sludges have a
higher heat value than digested sludges. For activated or digested
sludges with low heat values, supplemental fuels such as oil, natural gas,
or excess digester gas are suitable, although it would be pointless to
digest sludges prior to incineration; thus the two processes are not con-
sidered compatible. The multiple hearth furnace has been the most common
type of equipment used for combustion of sludges because it is simple,
durable, and it has the flexibility of burning a wide variety of materials
even with a fluctuation in the feed rates. Fuel (sludge) burned in an
incinerator emits heat; some is absorbed by the furnace and lost through
radiation, a larger portion is lost with the stack gases, and a smaller
portion is lost with the ash. The primary end products of combustion are
considered to be water, sulfur dioxide, carbon dioxide, and inert ash
(Ref. VI-12). The sulfur dioxide and particulates may be removed in the
TABLE VI-11
REPORTED SLUDGE HEAT VALUES
Description
Grease and Scum
Raw Sewage Solids
Fine Screenings
Digested Sewage Solids and
Ground Garbage
Primary Sewage Sludge
Activated Sewage Sludge
Semi-Chemical Pulp Solids
Digested Primary Sludge
Grit
Pennsylvania Anthracite
Coal (as a comparison to
the above)
Combustibles
(%)
88.5
74.0
86.4
49.6
59.6
33.2
Ash
(%)
11.5
26.0
13.6
50.4
40.4
69.8
Sludge
Heat Value
(Btu/lb)
16,750
10,285
7,820
8,020
8,990
6,540
5,812
5,290
4,000
13,880
Source: Ref. VI-58
- 140 -
-------
cyclonic jet scrubber and discharged with the ash as a slurry. In many
incinerators the waste gases from combustion are heated to 1250 F (677 C)
or higher to guard against odor nuisances. When land availability prevents
the use of lagoons for ash slurry disposal, the inert ash is stored dry and
periodically hauled away to convenient fill areas or possible by-product
uses such as filter media aids or construction concrete aggregate.
Dewatering of sludge to about 25- to 30-percent solids prior to
incineration in the multiple hearth furnace is usually required to prevent
corrosion of the furnace materials and to aid in the combustion process.
Extensive air pollution control processes capable of 96- to 97-percent
particulate removal efficiencies would be required to meet the national air
pollution standards for municipal sludge incinerators. These standards are
(1) no more than 0.65 g/kg dry sludge input (1.30 Ib/ton dry sludge input)
and (2) less than 20-percent opacity (Ref. VI-45).
Capacities of multiple hearth incinerators range from 200 to 8000 Ib/hr
of dry sludge with operating temperatures of 1700 F (Ref. VI-45).
A fluidized bed reactor incinerator is a relatively new process in the
wastewater sludge treatment field. The sludge, usually after degritting,
thickening, and dewatering, is fed into a bed of fluidized sand supported
by upward-moving hot gases. The sludge is burned in the hot sand bed, and
the ash is removed from the bed by the hot gases. The gases and ash are
scrubbed and cooled in wet gas scrubbing equipment generally using waste-
water treatment plant effluent as the scrubbing medium. The ash solids
may then be separated in a hydrocyclone and the scrubbing liquid returned
to the raw waste stream or recycled back to the scrubber. Advantages
claimed for these incinerators are a high degree of sludge oxidation; rela-
tively even operating temperatures; and relatively low operating costs
because, with wastes of sufficient heat value, the combustion process is
self-sustaining (Ref. VI-59). Loading rates of fluidized bed incinerators
range from 220 to 5000 Ib/hr of dry solids at 1400 to 1500 F.
Table VI-12 indicates the values obtained in the analyses of sewage
sludge exhaust gases from multiple hearth and fluidized bed incinerators.
Costs of incineration (both capital and O&M) are presented in Figures
IV-1 and IV-2 in Chapter IV.
Heat Drying
Heat (flash) drying is the instantaneous removal of moisture from
sludge solids by introducting them into a hot gas stream.
Wet sludge from a dewatering process is introduced into the cage mill
with some previously dried sludge and hot gases from the 1300 F furnace.
Drying is essentially completed in the cage mill; the sludge now approxi-
mately at 8- to 10-percent moisture. Dried sludge is separated from the
- 141 -
-------
CM
rH
H
t>
to
3
H
oo
£3
a
o
a
H
g
H
O
1-1
CO
H
^
c/o
ti
o
•H
CO
M
4->
CU
a
C
o
4.)
pj
0)
3
•H
CO
PI
0
0
cu
60
CO
^4
cu
CU
rl
CU
4-1
13
O
S
4-1
a
3
O
U
X
CO
4-t
^4
•rl
CO
CU
O
•s
cO
H
^
5
3
O
O
CO CM
<* . \ \ \ t III 100
I I I I I ill I • •
-J 1 1 1 1 1 III lOrH
rH CM CM U~i rH CM CM
NO in t*^ CT» in NO co NO t^ *3°
CO NO NO rH NO r~H f^ f^ SO f*^ f^\ f*^
o^ cj\ CM co in CM <"** <""i co O co co
-3- rH CN
rH
oo oo
oo in o oo o o -*
CO CO in rH CM O"* CO *^ CO
r*^ CN rH I rH OO O O *3" O O O^
• ••1 •* ••• •••
cor^co i CMO ooo ooo
O CM
co
m CM NO o CN
• CO t — 00 ^
COOO rHi-Hin rHCMOO
NO o^ i oo oo o o *3" o o cj\
• *jl* ••• •••
COCMrH | OOrH OOrH
Is"* •
CM -3"
»^-
<• i-H CO -» CM
NO - *sT i-H f^. OS 00 CO
rHt^.OOrHNOr-~ OOCO OO>*
OrHCOOOCM OOO OOO
^j
r-1
4J
(3
•H
O CO
rl &, CU
•rl 4J
CO 4J 0)
CD rH
f>, 0) 3 CO
rl 4-1 U Q)
•O -rt 4-1
4-1 4J CO
<4-t Cfl >-l rH
O CO 3
t-l O. O
• -H -H
H to I-i CU 4-1
O -'^^^•"'P MQ
>C06'^SSJ3 E Cfl fn
fr^ CU O-t rH C4« C^4 i-l N\3 C/5 ,G CJ C/i ,**!
O CU -^.^^ rH-^^^>^
CMW CM CM Xl-J rHOOCJOrH 4J6060rH
OoOOOOiH 0
O O
m m
NO NO
CO
r^ CM
tr> NO
**
CO
a
o
•H
4-1
•H
»rj
fj
O
U
co
CD
CU
O
O
rl
P-l
• •
CU
4J
0
2
CO
r^s r**-
CU CM
3
rl
CU
P.
4-* *^
cu m
CU CT\
u
,^5
U
-o
rl
CO
•T3
a
CO co
CO CM
*^^ r*4
s
CJ
to
i
CU
4->
CO
M
[5
Q
i-H
lM
f"^
0
cO
4-1
CO
1
1
I
CM
CM
CN
i-H
00
•
O
CM
CO
n
rl
•C
^S^.
CO
rO
H
-a
CU
cu
I4_l
U
00
3
i-H
CO
CTi
m
I
M
^
«
<4H
(U
erf
a)
o
V-l
3
0
CO
- 142 -
-------
spent gases in a cyclone and either sent to fertilizer storage or to the
furnace for incineration.
Primary combustion air is preheated in the deodorized gas heat ex-
changer and introduced into the furnace as combustion of fuel such as gas,
oil, coal, or wastewater sludge occurs. Ash accumulates in the furnace
bottom and must be periodically removed either by sluicing to an ash
lagoon, to a landfill, or to an ash utilization process such as vacuum or
filter press operation.
Effluent gases passing through the furnace and combustion air pre-
heater then pass through a dust collector and an induced draft fan to a
discharge stack.
The use of this system for incineration alone has not proven attractive.
Recovery of the dried sludge for sale as a fertilizer is currently practiced
in Houston, Texas. Long-term contracts have produced revenues of approxi-
mately $21/ton of product. The dried product had a moisture content of
five percent; ash, 35 percent; nitrogen, 5.3 percent; and available
phosphoric acid, four percent (Ref. VI-45). As an incineration unit, the
flash drying system has the disadvantages of complexity, potential for
explosions, and potential for air pollution by fine particles.
Pyrolysis
Pyrolysis is the destructive distillation of refuse, sewage sludge,
or other organic materials under pressure and heat in the absence of
oxygen. Most of the combustion process is carried out within a closed
reactor chamber, normally at temperatures nower than in incinerators.
The pyrolysis process has been used c a a very limited basis and pri-
marily on municipal refuse rather than sewage sludges. Where municipal
refuse has been pyrolized, the products have been gases, pyroligneous acids
and tars, and char. The gases consist mainly of hydrogen, methane, carbon
monoxide, carbon dioxide, ethane, and ethylene. Tables VI-13 and VI-14
give the product yield and the approximate analysis of the pyrolysis char,
respectively, of the pyrolysis of municipal refuse in San Diego, California
(Ref. VI-13). The pyrolysis of digested sewage sludge yields the same
products as those from the solid waste, although the char shows about 70 to
75 percent lower BTU content (Ref. VI-13).
There is an advantage to combining a pyrolysis plant with a sewage
treatment facility to conserve energy and to help each of the individual
processes. Methane from anaerobic digesters at the sewage plant could be
used as a fuel in the pyrolysis system, while the waste heat from pyrolysis
could, in turn, be used to aid sludge digestion. The char from the
pyrolysis might be used as a filter aid in the sewage plant vacuum filter
or centrifuge operations.
- 143 -
-------
TABLE VI-13
PYROLYSIS PRODUCT YIELD
Temperature
(°F)
900
1,200
1,500
1,700
Product Yield Percent by Weight
Gases
12.33
18.64
23.69
24.36
Pyroligneous
Acids
and Tars
61.08
59.18
59.67
58.70
Char
24.71
21.80
17.24
17.67
Mass
Accounted
for
98.12
99.62
100.59
100.73
Source: Ref. VI-13
TABLE VI-14
PROXIMATE ANALYSIS OF PYROLYSIS CHAR
Proximate Analysis of Pyrolysis Char at
Indicated Temperature (°F)
Volatile
matter, %
Fixed carbon, %
Ash, %
Btu per Ib.
900
21.81
70.48
7.71
12,120
1200
15.05
70.67
14.28
12,280
1500
8.13
79.05
12.82
11,540
1700
8.30
77.23
14.47
11,400
Source: Ref. VI-13
- 144 -
-------
A sludge pyrolysis process is scheduled for operation by 1977 in
Minneapolis/St. Paul, Minnesota (Ref. VI-60). The system will take 15 to
40 percent of the dewatered sludge from the secondary wastewater treatment
system to the pyrolysis unit for disposal. The sludge pyrolysis unit will
use municipal refuse as the source of fuel for the processing of sludge and
production of both fuel char and process char which can be used in augment-
ing the overall treatment and sludge disposal system.
The major features of the system were described as follows (Ref. VI-60)
"A mixture of sludge and refuse is dried to remove most of
the moisture and then fed into a rotary kiln. The kiln is
externally heated by a furnace that burns the gaseous and liquid
fuels derived from the pyrolysis off-gasses. The mixed material
is thoroughly agitated and exposed to temperatures of 1250 F for
30 to 60 minutes, driving off volatiles and leaving a char
material consisting mainly of carbon and ash.
"The kiln off-gasses are collected and processed in a gas
cleaning system that condenses out the tar and oils. The
remaining gas is suitable for fuel gas, having a heat value of
approximately 450 BTU per standard cubic foot. The product gas
is stored in a gas holder and continuously delivered to the
kiln furnaces as needed to support the mixture drying and
pyrolysis operation. Excess gas is used to supplement other
thermal needs.
"The tar and oils condensed from the pyrolysis off-gas
stream are stored in tanks, then blended to produce fuel oil,
and finally delivered to oil burning devices within the plant.
"The char produced by the pyrolysis kiln is cooled and
delivered to a sizing and de-ashing processing stage that
produces three fractions: Char suitable for processing into
activated carbon; fuel-grade high ash char for delivery to the
primary sludge incinerators to reduce the need for purchased
fuels; and a residue of inert ash, containing some fixed
carbon, to be disposed of in a landfill."
The various fuels produced in the operation will be incorporated into
the overall system thus reducing the need for purchased fuel oil and
natural gas. Cellulose products, ferrous metals, glass, and aluminum will
be sorted from the refuse and sold to provide an additional source of
revenue. Refuse in excess of the system's needs will be baled and taken
to a sanitary landfill where it will occupy less than one-half the space
per ton required in conventional sanitary landfill practice.
- 145 -
-------
Pyrolysis, being a new concept applicable to wastewater treatment
sludges, has not had a separate, detailed breakdown of costs. Table VI-15
does, however, indicate the costs estimates for a complete sludge treat-
ment system which includes pyrolysis. It was noted that from 15 to 40 per-
cent of the dewatered sludge from the secondary subsystem (approximately
63,000 to 168,000 pounds of dry solids per day) would go to the pyrolysis
unit (Ref. VI-60).
Lime Recalcination
Lime is often used in wastewater treatment as a coagulant for
phosphorus removal. It can be applied either as a tertiary step or ahead
of the primary clarifiers in either a biological or physical-chemical
wastewater treatment plant.
The process of recalcining involves heating the dewatered sludge con-
taining calcium driving off the water and carbon dioxide and leaving the
calcium oxide (quicklime). When coagulating raw wastewaters, the inert
solid fraction can be removed before recalcination by centrifugation.
This inert solid removal must occur to prevent solids buildup within the
wastewater treatment process.
The advanced wastewater treatment plant at South Lake Tahoe, Nevada,
has used lime recalcination to recover lime for reuse since April 1968.
Over this period makeup lime has accounted for 28 percent of the calcium
oxide used (Ref. VI-45). The advanced wastewater treatment plant planned
for Cleveland, Ohio, also anticipated the use of lime recovery by recal-
cination in a multiple-hearth incinerator. It is anticipated that, from
a total daily sludge solids production of 196,900 pounds for the average
daily flow of 50 MGD, approximately 62,400 pounds per day of lime can be
recovered (Ref. VT-61).
Table VI-16 indicates the costs for recalcination of lime sludge
(Ref. VI-62). The total capital cost includes thickening, centrifugation
(dewatering) and the furnace. Make-up lime was computed using the assump-
tion that 350 mg/1 of lime (CaO) is required and that 1.2 ton/day/mgd of
lime is recovered through recalcination.
Composting
Composting is the biochemical decomposition of organic matter in
municipal, agricultural, and industrial wastes resulting in a generally
sanitary, nuisance-free, humus-like material. The main value of this
material is due to its high organic ccntent which can act as a soil con-
ditioner providing poor soils with better tilling properties, water-holding
capacity, and improved nutrient-holding capacity (Ref. VI-63). However,
compost is not a complete fertilizer unless it is supplemented by addi-
tional nutrients. A good compost could possess up to two-percent nitrogen,
one-percent phosphoric acid, and many trace elements (Ref. VI-12) .
- 146--
-------
§
B
o
3
C
C
•
(A
o
4
•*-*
D.
n
o
r-f
•-« 4 4 A
4 3 4J O
W C 10 0
o q o o
H < O ^^
w
00 U
e c
AJ T3 C O
4 C 41 0
Jj « *J O
V C ^
(X *<
O 4
*
X
r-« b
U > *-> O
O. U O
4 4> *-^
u P:
«-4 *--.
4 0
*J O
0 2-
-»-t C
H 4 <•>.
w O
41 *H 01 O
C « «H O
OO 4» -4
c j a
ui -5
O
-o -*4
41 *J
U Cl U x-s.
efl 3 01 O
6 M 0 0
1-t *j (J O
4-» ffl '*••'
4 C
Ul 0
U
vt »r» r-
CD m
^
~
1 1 1
1 1 1
i i 1
1 I 1
i J !
00 CO 00
c c c
44 ±1 U
BO U> 4
XXX
00
V
4J
4>
c
0 4
41 n
*- QO C
0 CO
X -^ —
4 C U
.0 •-* O 4
3 ft) -^ U
tO GO *J 41
•0 -^ C
4i t- -a •*-<
00 O C O
•c " o e
3 « O -^
r-t
VI 41 «» *
CM] W OO
x TJ -a "O
U 333
B (/) to i/>
C-
rH ^T « ^
O «-4 *^» r^
f* C4 r-4
C»l »rt rH V»
- o *o ^
40-
O r-* oo
O CT> -T OO
^
OO O *O *T
«-J CT» 03 ^»
«y>
r- O •-< -*
r^ o < CO 7
u
CO
«» »0 CO
•"• O *O
f* «*4 *^
rH «O -»
**5 *O O
rH V> O
•* •* °*
ON o m
<*^ OO O
<-» o o
(-4 t-t
C 4
41 00 X
4 41
•o *o -a
333
tn ui vi
0 fN CO
00 O f-
O ^ -*
•* tM <^*
*-< <-4
«/V «*•
in
f-4
GO
.
r-
*\
CO
o%
"1
°1
p-
3 O
C U
41 4
C
-t C
3
i «
4 u
4 O
4 4
O O V
l-t H Z
c
o • w
»< « a
H2i
A »w O 4
u d
•H S 4 C
X 4 W O
* a m c
o
4 TJ O JS
§§S
O O O
8
o
U 4
' 41 C
«S J
5* g
~4 m a
X O -rl
vac
o « e
e o
•*4 « U
_ "2 _
u A eb
w o -a
o e js
zs"
-c s
o o C
o
oc-a u
C B 4
C *M »H
00 W 3
C 3 O.«M
•ss§s
•5^-° B
O 41 O O
u u -o e
JS
" X
0X3
U U B
* E ° 3 '
C V D. u -
a «
• « >
u o
.-I !-• K.
U fcj u > fB X I
« « « « v\ ft. a
uuuiuuxza*.
X -*4
I U U. I
- 147 -
-------
vO
I
M
1
CA3
§
PH
§
M
S3
CJ
s
o
3
to
M
s
§
S
CJ
w
Pi
r^
4-J
•H
O
ed
P<
ed
1
4
h
-d
00
B
o
CO
*rj
00
6
o
rH
*"O
s
H
O
iH
'O
00
"
rH
2
I)
j
H
0
o
o CN vo o r~ en o en
•» o\ vo cy\ r^- vo co in oo
in
*
en
O
O
o oo o O en o
« CNCnavrHvOOt-~CO
O
CSI
o m o vo en o ••d"
co in cy* o*» en vo co CN oo
O VOinrHcNOrHOO-*
O rH
vO
O O vO en O
O 00 CT\ O vo O en OO
o iHini-tooorHcn^-
O in CN rH
o
CN
*
•d
cd
CU
J.CI
M
CU
W M >
C (>s O
O C
rH O rH * O
rH CN rH * 4J
CO Cd O CO ~-^
M oo *a t-i rH o
cd c f^ cd m
rH O cd Cd *H •
rH O M P-l r-l CO
O O B^S O CU M rH
"O rHr-.}-JrQ'rJ4JCU
*^^ o cd fj cd ^
"CO * o ( 1 (rj ^grj Q «v
4-i 4J c cd P-I CD
COCOrJCUtlCU 6
OCU-H CJOCJrH -H
cd c! cd co cd o
rH -N-rlC'rHC-H G,
Cd 4J-H4JCUp»CUrl P
4_J CO 4-J rt 4-J H 4-) 4J |
•rH O ^4 M r3 CU c3 CJ rH CU
f\t cj o Q) *H pt «H CU CU r^
eO fi Q4 ed 3 cd rH ?3 cd
cj co ^ o )Z2 cy^ JsJ W P-i ^»"]
CO
rH CU
O M
H P-.
CO rH
0 ?*.
CO
0 T3
o ~^
o co
rH (3
• — o
CO 4-> C
4J O
PI •* 4J
cu ?>, ~~.
CJ 4-1 CO
•H 1-1
« O CO
4J ed iH
CO P. rH
O ed o
O O TJ
Pi 4J «
0 Pi 4J
•H ed co
4J rH O
cd fii cj
•H Pi C
CJ 0 0
rH -H >H
CO 4-1 4-1
CJ CO Cd
CU pi C
Pd iH iH
o o
rH rH rH
4-" CJ O
o cu cu
H pi Pi
M
O
"rt
H
CU
CJ
cd
§
rt
a)
OH
O
o
en
co
cd
C
cu
•a
H
*
ed
•H
CU
4-1
cd
a
m
CN
cd
rH
in
4J
CO
O
O
CU
a
cd
c
cu
cd
B
TJ rH
cd cu
CJ
oo c
pi cd
•H c
cu
cd
B
cn
ed
c
cu
ed
H
*
*
CM
MH
&
cu
CJ
o
C/)
- 148 -
-------
Degradation is accomplished by windrowing the waste with periodic
mixing or by aeration in a mechanical device (Ref. VI-45). From the EPA
manual on sludge treatment and disposal (Ref. VI-45), the following
sequential steps are usually involved in composting:
(1) Preparation - Sludge may be and is often blended with a bulking
material, e.g., sawdust or wood chips. The final moisture con-
tent should exist between 45 and 65 percent by weight. Normal
sludge to bulking material ratios are usually about 0.50 to 1.00
by weight.
(2) Digestion - During decomposition, air must be supplied to the
compost by agitation or forced draft. Wastes usually reach a
temperature of 140 F to 160 F. These temperatures kill many
pathogens. Digestion generally requires about six weeks for
windrows and several days for mechanical aeration methods.
Digestion is considered complete when the carbon-nitrogen ratio
of the compost reaches 20 to 1.
(3) Curing - The decomposition rate is slowed until digestion is
brought to completion usually in two more weeks for a windrow
system and in one to two weeks for mechanical methods.
(4) Finishing - Screening to remove large objects may be necessary.
In marketing compost, a company in San Francisco (as of 1968 - Ref.
VI-12) has been selling a composted mixture of digested sewage sludge,
coffee grounds, and rice hulls. However, in general composting plants are
not profitable ventures owing to lack of a market for compost. Of the
18 plants built between 1951 and 1969 in the United States, only a few are
currently operated and many of these are operated only occasionally (Ref.
VI-12).
The cost of composting varies widely and ranges from (October 1974)
$2 to $20/ton (Ref. VI-45). The sale of compost usually brings a revenue
of $1.50 to $3.50/ton of material fed. A pilot composting plant (Ref.
VI-64) in Maryland estimates costs (June 1974) of $7.31 per wet ton or
$30 per dry ton for processing 200 wet tons per day (20 percent solids,
digested sludge).
Sludge Recycle/Marketing
In a previous section of this chapter, sludge recycle was discussed
in detail concerning direct application of sludge by public or semi-public
institutions to farmland. This section will briefly discuss the retail
sale of processed sewage sludge (amenable to sale by private entrepreneurs)
for agricultural purposes.
In general, the sale of processed (usually dried) sludge suffers the
same problem of non-marketability that afflicts the other resource recovery
methods previously discussed. While processed sludge is a good fertilizer
- 149 -
-------
and soil conditioner, commercial fertilizers have a higher nutrient content
for a given price. Thus, the commercial fertilizer will usually be pre-
ferred.
In the Washington, D. C., area (Ref. VI-65 ) a private company is
planning to sell dried sewage sludge as a 6-4-10 (percent nitrogen,
phosphoric acid, potash) fertilizer at a price (June 1974) of about five
dollars per 50 Ib bag. The profitability of such a venture is unknown,
especially since a commercial fertilizer provides a much higher nutrient
content for that price.
The City of Winston-Salem (Ref. VI-66) tried to market air-dried
sludge sold under the name of "Grogonite." Grogonite contained approxr'
mately three percent nitrogen, three percent phosphoric acid, and less
than two-tenths of one percent potash. This product would sell (1973) for
about $18 to $20 per ton. Marketing of Grogonite was not a profitable
venture due to inhibiting marketing laws and institutional hesitancy ir
becoming involved in marketing and selling and promoting the product. The
City decided to stop trying to sell Grogonite but instead to sell their
air-dried sludge to Organics, Inc. of Rhode Island (State) which makes and
sells a commercial fertilizer component named Organiform-SS. urganics,
Inc. will return to the city a net payment (1973) of $5 per ton.
Milwaukee and Chicago (Ref. VI-12) have marketed heat-dried activated
sludge at a price (updated to 1975) generally between $23 and $34 per ton
(not a profit, however). The City of Milwaukee sells their sludge under
the trade name of Milorganite which contains six-percent nitrogen, four-
percent phosphate, 0.4-percent potash, and like most organic sludges,
numerous agriculturally beneficial trace elements (Ref. VI-12).
In summary dried organic sludge can be used for agricultural purposes
thus serving as a form of resource recovery and coincidently disposing of
a residual waste. However, due to the relatively high cost of processing
(for the resulting nutrient value as a fertilizer) compared to commercial
fertilizers, the sludge cannot be profitably marketed.
- 150 -
-------
CHAPTER VI
REFERENCES
VI-1 Sanitary Landfill, Committee on Sanitary Landfill Practice,
American Society of Civil Engineering, Manuals of Engineering
Practices, No. 39 (1959).
VI-2 Cleaning Our Environment - The Chemical Basis for Action,
American Chemical Society, Washington, D. C. (1969).
VI-3 "Proposed Guidelines for Land Disposal of Solid Wastes - Environ-
mental Protection Agency," Federal Register, Vol. 38, No. 81
(April 27, 1973).
VI—4 Second Report to Congress-Resource Recovery and Source Reduction,
U.S. Environmental Protection Agency, Pub. SW-122 (1974).
VI-5 "Foundation Problems in Sanitary Landfills," Sowers, G. F.
American Society of Civil Engineers, Journal of Sanitary Engineer-
ing, Vol. 94, No. 54 (1968).
VI-6 Solid-Waste Disposal in the Geohydrplogic Environment of Maryland,
Otton, E. G., Maryland Geological Survey, Report of Investigation
No. 18 (1972).
VI-7 Sanitary Landfill Design Criteria; Department of the Navy, pre-
pared by Engineering-Science, Inc., for Naval Facilities Engineer-
ing Command (1973).
VI-8 Development of Construction and Use Criteria for Sanitary Land-
fills, an Interim Report prepared by County of Los Angeles and
Engineering-Science, Inc. for U. S. Department of Health, Educa-
tion and Welfare (1969).
VI-9 "Refuse Disposal, Its Significance," Weaver, Leo, in Groundwater
Contamination, Proceedings of 1961 Symposium, U. S. Department of
Health, Education and Welfare, Robert A. Taft Engineering Center
Technology Report W 61-5 (1961).
VI-10 "Leaching from Simulated Landfills," Quasim, S. R., and Burchenal,
J. C., Journa^L of the Water Pollution Control. Federation, Vol. 42,
No. 3, Part 1 (1970).
VI-11 Recommended Standards for Sanitary Landfill Design, Construction,
and Evaluation and Model Sanitary Landfill Operation Agreement,
Publication SW-86ts, U. S. Environmental Protection Agency (1971).
- 151 -
-------
CHAPTER VI
REFERENCES
(Continued)
VI-12 A Study of Sludge Handling and Disposal, Burd, R. S., Publication
WP-20-4, U. S. Department of the Interior, Federal Water Pollu-
tion Control Agency (1968).
VI-13 Stanley Engineers, "Sludge Handling and Disposal, Phase I, State
of the Art," Report to Metro Sewer Board of Twin Cities Area
(1972).
VI-14 Ultimate Disposal of Sludge in Jnland Areas, Riddell, M. D. R.,
and Cormack, J. W., paper presented at 39th Annual Meeting of
Central States Water Pollution Control Association, Eau Claire,
Wisconsin (1966).
VI-15 Changing Times (March 1, 1974).
VI-16 Disposal of Wastes from Water Treatment Plants, Department of the
Interior, Federal Water Pollution Control Agency (1969).
VI-17 Sludge Dewatering - WPCF Manual of Practice No. 20, Water Pollu-
tion Control Federation (1969).
VI-18 Methods of Final Disposal of Effluents Brines from Inland^
Desalination Plants, Dow Chemical Company, U. S. Department of
the Interior, Office of Saline Water (1972).
VI-19 "Evaluation of Sludge Treatment and Disposal," Canadian Munici-
pal Utilities, MacLaren, J. W. (1961).
VI-20 "Using Treated Sewage Effluent for Crop Irrigation," Weiss,
R. H., Compost Science, Autumn (1961).
VI-21 "Land Disposal IV: Reclamation and Recycle," Dalton, F. E., and
Murphy, R. R., Journal of the Water Pollution Control Federation,
Vol. 45, No. 7 (1973).
VI-22 "Sludge Disposal Practices in the Pacific Northwest," Leaver,
R. E., Sewage and Industrial Wastes. Vol. 31, No. 11 (1959).
VI-23 "Crop and Food Chain Effects of Toxic Elements in Sludges and
Effluents," Chaney, R. L., Proceedings of the Joint Conference
on Recycling Municipal Sludges and Effluents on Land, Champaign,
Illinois (1973).
- 152 -
-------
CHAPTER VI
REFERENCES
(Continued)
VI-24 "Land Disposal I: A Giant Step Backward," Egeland, D. R.,
Journal of the Water Pollution Control Federation, Vol. 45, No. 7
(1973).
VI-25 "Chemical and Biological Quality of Municipal Sludge," Peterson,
J. R., Lue-Hing, Cecil; and Zing, D. R., Recycling Treated
Municipal Wastewater and Sludge Through Forest and Cropland,
The Pennsylvania State University Press, University Park,
Pennsylvania (1973).
VI-26 Wastewater Management by Disposal on the Land, Corps of Engineers,
U. S. Army, Cold Regions Research and Engineering Laboratory,
Special Report 171 (1972).
VI-27 "Inorganic Reactions of Sewage Wastes with Soils," Lindsay,
W. L., Proceedings of the Joint Conference on Recycling Munici-
pal Sludges and Effluents on Land, Champaign, Illinois (1973).
VI-28 "Federal and State Legislative History and Provisions for Land
Treatment of Municipal Wastewater Effluents and Sludges,"
Sullivan, R. H., Proceedings of the Joint Conference on Recycling
Municipal Sludges and Effluents on Land, Champaign, Illinois
(1973).
VI-29 Utilization of Municipal Wastewater Sludge, Manual of Practice
No. 2, Water Pollution Control Federation, Washington, D. C.
(1971).
VI-30 "Nitrogen Removal by Soil Mechanisms," Journal of the Water
Pollution Control Federation, Vol. 44, No. 7 (1972).
VI-31 Municipal Sewage Effluent for Irrigation, C. W. Wilson and R. E.
Beckett (Eds.), The Louisiana Tech Alumni Foundation, Ruston, 49
(1968).
VI-32 "A Spray Irrigation System for Treatment of Cannery Wastes,"
Gilde, L. C., Journal of the Water Pollution Control Federation,
Vol. 43, No. 10 (1971).
VI-33 "Rutgers Symposium Reviews Land Disposal of Municipal Effluents
and Sludges," Compost Science, Vol. 14, 3, 26 (1973).
- 153 -
-------
CHAPTER VI
REFERENCES
(Continued)
VI-34 Sludge Application on Agricultural Land, Aldrich, S. R. (unpub-
lished manuscript), Illinois Agricultural Experiment Station,
Champaign, Illinois (1973).
VI-35 Water Quality Improvement by Physical-Chemical Processes, Gloyna,
E. F., and Eckenfelder, W. W., Jr. (Eds.), University of Texas
Press, Austin (1970).
VI-36 "Land Application of Liquid Municipal Wastewater Sludges,"
Hanson, R. J., and Merritt, C. A., Journal of the Water Pollu-
tion Control Federation, Vol. 47, No. 1 (1975).
VI-37 "Physical Changes to Soils Used for Land Application of Municipal
Waste - What Do We Know? What Do We Need to Know?" Erickson,
A. E., Proceedings of the Joint Conference on Recycling Municipal
Sludges and E_ffluents on Land, Champaign, Illinois (1973).
VI-38 Acceptable Methods for the Utilization or Disposal of Sludges,
Technical Bulletin - Supplement to Federal Guidelines: Design,
Operation and Maintenance of Wastewater Treatment Facilities
Proposed for Public Comment, U. S. Environmental Protection
Agency (1974).
VI-39 "Soil Microbiological Aspects of Recycling Sewage Sludges and
Waste Effluents on Land," Miller, R. H., Proceedings of the
Joint Conference on Recycling Municipal Sludges and Effluents
on Land, Champaign, Illinois (1973).
VI-40 "Factors Affecting Nitrification-Denitrification in Soils,"
Broadbent, F. E., Recycling Treated Municipal Wastewater and
Sludge Through Forest and Cropland, The Pennsylvania State
University Press, University Park, Pennsylvania (1973).
VI-41 "Effects on Land Disposal of Wastewaters on Soil Phosphorous
Relations," Hook, J. E.; Kardos, L. T.; and Sopper, W. E. ,
Recycling Treated Municipal Wastewater and Sludge Through Forest
and Cropland, The Pennsylvania State University Press, Univer-
sity Park, Pennsylvania (1973).
VI-42 Proceedings of Conference on Land Disposal of_Municipal Effluents
and Sludges, Rutgers-The State University of New-Jersey (March
1973).
- 154 -
-------
CHAPTER VI
REFERENCES
(Continued)
VI-43 "Utilization of Digested Chemical Sewage Sludges on
Agricultural Lands in Ontario, Black, S. A., Proceedings of the
National Conference on Municipal Sludge Management, Pittsburgh,
Pennsylvania (June 1974).
VI-44 "Soil-Plant Relationships - Some Practical Considerations in
Waste Management," Melsted, S. W., Proceedings of the Joint
Conference on Recycling Municipal Sludges and Effluents on
Land, Champaign, Illinois (1973).
VI-45 Process Design Manual for Sludge Treatment and Disposal, U. S.
Environmental Protection Agency Technology Transfer
(EPA 625/1-74-006) (1974).
VI-46 Pipeline Transport of Digested Sludge to Strip Mine Spoil Site
for Spoil Reclamation, prepared by Engineering-Science, Inc.
for the Office of Research and Monitoring, U. S. Environmental
Protection Agency, Washington, D. C., Contract No. 14-12-805
(1973).
VI-47 "Restoration of Acid Spoil Banks with Treated Sewage Sludge,"
Lejcher, T. R., and Kunkle, S. H., Recycling Treated Municipal
Wastewater and Sludge through Forest and Cropland, The Pennsyl-
vania State University Press, University Park, Pennsylvania
(1973).
VI-48 "Institutional Options for Recycling Urban Sludges and Effluents
on Land," Barbolini, R. R., Proceedings from the Joint Conference
on Recycling Municipal Sludges and Effluentsi cm Land, Champaign,
Illinois (1973).
VI-49 "Ocean Disposal Subject to New Controls," Environmental Action,
Journal of the Water Pollution Control Federation, Vol. 45, No. 5
(1973).
VI-50 Ocean Dumping- A National Policy, Council on Environmental
Quality (1970).
VI-51 Ocean Disposal Practices and Effects, President's Water Pollu-
tion Control Advisory Board (1972).
VI-52 Ocean Dumping - Final Regulations and Criteria, Environmental
Protection Agency, Federal Register, Vol. 38, No. 198 (1973).
- 155 -
-------
CHAPTER VI
REFERENCES
(Continued)
VI-53 "Economic Considerations for Planning Sewage Sludge Disposal
Systems," Pretreatment and Ultimate Disposal of Wastewater Solids,
Research Symposium at Rutgers University, New Jersey (May 1974).
VI-54 Investigation of the Feasibility of a Submerged Ocean Outfall
System for the Disposal of a Clay Slurry Waste - Monterey
Peninsula, California, Engineering-Science, Inc., Oakland,
California (1961).
VI-55 The Barged Ocean Disposal of Wastes. A Review of Current
Practice and Methods of Evaluation, Clark, B. D., et_ a±, EPA,
Pacific Northwest Water Laboratory (1971).
VI-56 Ocean Disposal of Barge-Delivered Liquid and Solid Wastes from
U. S. Coastal Cities (SW-19c), Smith, D. D., and Brown, R. P.,
U. S. Environmental Protection Agency, Solid Waste Management
Office (1971).
VI-57 Economics of Regional Waste Transport and Disposal Systems,
Thompson, T. L.; Snoek, P. E.; and Wasp, E. J., presented at the
Third Joint AICHE-IMIQ Meeting, Denver, Colorado (September
1970).
VI-58 Planning and Technical Considerations for Ultimate Disposal of
Residual Wastes, Wyatt, J. M., prepared for the Office of Research
and Monitoring, U. S, Environmental Protection Agency, Contract
No. 68-01-2222 (August 1974).
VI-59 Analysis of the 1973 Sewage Sludge Disposal Problem in Southern
California, Bursztynsky, T. A.; Davis, J. A.; Feuerstein, D. L. ;
Doyle, A. A.; and MacLaren, F., prepared for the Implementation
Research Division, U. S. Environmental Protection Agency, by
Engineering-Science, Inc. and J. B. Gilbert and Associates
(draft, June 1974).
VI-60 "Sludge is Beautiful in the Twin Cities," Storck, W. J.,
Water and Wastes Engineering (July 1974).
VI-61 Westerly Advanced Wastewater Treatment Facility - Process
Development and Engineering Design, Zurn Environmental Engineers
for the City of Cleveland, Ohio (June 1972).
- 156 -
-------
CHAPTER VI
REFERENCES
(Continued;
VI-62 Cost and Performance Estimates for Tertiary Wastewater Treating
Processes, FWPCA Advanced Waste Treatment Research Laboratory,
Report No. TWRC (June 1969).
VI-63 Composting of Municipal Solid Wastes in the United States
(No. SW-47r), Solid Waste Management Research Staff, U. S.
Environmental Protection Agency (1971).
VI-64 "Composting Sewage Sludge," Epstein, E.t and Willson, G. B.,
Proceedings of the National Conference on Municipal Sludge
Management, Pittsburgh, Pennsylvania (June 1974).
VI-65 "Alternative Methods for Sludge Management," Bernard, H.,
Proceedings of the National Conference on Municipal Sludge
Management, Pittsburgh, Pennsylvania (June 1974).
VI-1" "Sludge Recycling: The Winston-Salem Experience," Styers, F. C.,
Proceedings of a National Symposium on Ultimate Disposal of
Wastewaters and Their Residuals, Research Triangle Universities,
N. C., and U. S. Environmental Protection Agency - Region IV
(April 1973).
- 157 -
-------
CHAPTER VII
EVALUATION PROCEDURES. CRITERIA. AND CONSTRAINTS
INTRODUCTION
Within the confines of the geographic areas covered under regional
plans prepared for Section 208, an administrating state or regional planning
agency may have several residual waste management options to consider. An
optimum management option is a system that will reliably meet the criteria
set for the system in an economic and resourceful manner. The costs
incurred by and benefits derived from each alternative must be evaluated
in an equitable and systematic fashion as a prerequisite to rational
decision-making. Facilities costs can be readily calculated because
society places an identifiable value on the labor and materials necessary
for their operation and construction. However, difficulties arise when
less tangible environmental aspects of the options are to be evaluated.
The value of clean waters, fresh air free from odors, absence of noise, and
beautiful, productive lands in a community are subject to different inter-
pretations by individuals varying in their points of view.
The purpose of the remaining sections of this Chapter is to provide
to 208 planning staffs a framework within which reasonable residual waste
disposal and/or reuse alternatives can be chosen and evaluated in a
systematic manner, utilizing information supplied in this report, guidelines
issued by the Environmental Protection Agency, and previous reports which
can be obtained for use by the planning agency.
SELECTION OF ALTERNATIVE RESIDUAL WASTE HANDLING PROCESSES
Previous Chapters of this report have discussed the individual elements
of residual waste generation sources, means of residual waste treatment and
treatment and transport, and methods of residual waste disposal and/or reuse.
Figure VII-1 indicates the pathways in which these elements relate to one
another. It becomes obvious from this figure that there are numerous
methods by which residual wastes may be treated, transported, and disposed
or reused. Figure VII-2 indicates the pathways most likely to occur, both
in terms of the most commonly employed means of wastewater treatment and
sludge handling and disposal as well as the compatability and reliability
of process selection and sequencing. More detailed information on the
individual process shown in Figure VII-2 may be found in Chapters III (for
sludge producing unit processes), Chapter IV (for sludge handling unit
processes), and Chapter V (for transport methods). Table VII-1 indicates
the description of the pathway elements.
Using Figure VII-2, the planner can select the known wastewater treat-
ment processes and then follow the pathways indicated to obtain numerous
sludge handling options. As mentioned in Chapter II, this is the equivalent
- 158 -
-------
FIGURE 3ZH-I
WASTE PROCESSING AND DISPOSAL / REUSE ALTERNATIVES
_i
0 ^
CL ^
ootc
TRANS-
PORT
DRYING AND
REDUCTION
DEWATERING
CONDITIONING
AND
STABILIZATION
THICKENING
_i
Z>
Q
CO
LU
o:
Q
<,-
0 Ul H-
z cc ui
< 0. 5
o
<_
|_ 1
LANDFILL
|
TRUCK
_i
<
cr
1
1 1
r— INCINERATION
1
VACUUM
1 FILTRATION
HWET AIR
OXIDATION
CENTRIFUGATION j
DISPOSAL
PONDS
J_ J
PIPELINE
1
OCEAN
Ul
15
IT
<
m
1
0
H?
< >
uj tr
X D
PRESSURE
FILTRATION
1
ANAEROBIC
DIGESTION
AEROBIC
DIGESTION
1 I
U PYROLYSIS
1
— | LAGOONS
CHEMICAL
TREATMENT
r"
DISSOLVED
AIR
FLOATATION
1
ELUTRIATION
1
GRAVITY
SLUDGE
GENERATION
CENTRIFUGATION
RECLAMATION
L- RECALCINATION
o? in
-------
FIGURE 2H-2
- 160 -
-------
TABLE VII-1
DESCRIPTION OF PATHWAY ELEMENTS
Sludge-Producing Unit Processes (see Ch. Ill for greater detail)
A. Primary Sedimentation
A-l Conventional
A-2 Two-State Lime Addition
A-3 Single Stage Lime Addition
A-4 Alum Addition
A-5 FeCl3 Addition
B. Trickling Filter
B-l Influent: Effluent from A-l
B-2 Influent: Effluent from A-3
B-3 Influent: Effluent from A-4 or A-5
C. Activated Sludge
C-l Coventional
Influent: Effluent from A-l
C-2 Conventional
Influent: Effluent from A-3
C-3 Conventional
Influent: Effluent from A-4 or A-5
C-4 Alum Addition
Influent: Effluent from A-l
C-5 FeCl3 Addition
Influent: Effluent from A-l
C-6 High Rate
Influent: Effluent from A-l
D. Two-Stage Tertiary Lime Treatment
D-l Influent: Effluent from B-l
D-2 Influent: Effluent from C-l
Sludge Handling Unit Processes (see Ch. IV for greater detail)
E. Heat Treatment
E-l Sludge Influent: Generated from A-l+B-1, C-l or C-6
E-2 Sludge Influent: Generated from A-l+C-4 or C-5,
A-4+B-3 or C-3, A-5+B-3 or C-3
F. Anaerobic Digestion
F-l Sludge Influent: Generated from A-l+B-1, C-l or C-6
F-2 Sludge Influent: Generated from A-l+C-4, or C-5
A-4+B-3 or C-3, A-5+B-3 or C-3
G. Sand Drying Beds
G-l Sludge Influent: Effluent Sludge from F-l
G-2 Sludge Influent: Effluent Sludge form F-2
- 161
-------
TABLE VII-1
(Continued)
H.
Dewatering -
H-l Sludge
H-2 Sludge
H-3
H-4
H-5
H-6
H-7
H-8
H-9
Sludge
Sludge
Sludge
Sludge
Sludge
Sludge
Sludge
Vacuum Filtration
Influent: Generated from A-l+B-1, C-l or C-6
Influent: Generated from A-l+C-4 or C-5
A-4+B-3 or C-3, A-5+B-3 or C-3
Influent: Generated from A-2
Influent: Generated from A-3+B-2 or C-2
Influent: Effluent Sludge from P-l
Influent: Effluent Sludge from P-2
Influent: Generated from D-l or D-2
Influent: Effluent Sludge from E-l
Influent: Effluent Sludge from E-2
Incineration -
1-1 Influent
1-2 Influent
1-3 Influent
1-4 Influent
1-5* Influent
P-6 Influent
P-7 Influent
Multiple Hearth
Sludge Effluent Sludge from H-l
Sludge Effluent Sludge from H-2
Sludge Effluent Sludge from H-3
Sludge Effluent Sludge from H-4
Sludge Effluent Sludge from H-7+H-1
Sludge Effluent Sludge from H-8
Sludge Effluent Sludge from H-9
Recalcination (includes chemical storage and feeding)
J-l Sludge Influent: Effluent Sludge from H-3
J-2 Sludge Influent: Effluent Sludge from H-4
J-3 Sludge Influent: Effluent Sludge from H-7
Note: Use pathway from H-l to 1-5
only when D-l or D-2 is included
in the complete system.
Source: Ref. VII-1
of the first situation, namely that a wastewater treatment facility (or
facilities) already exists. Similarly, if certain sludge disposal options
(as discussed in Chapter VI) appear the most suitable for use in the 208
planning area, the planner can enter Figure VII-2 at the bottom and follow
the pathways back to various wastewater treatment options. Thus, the second
situation as described above and discussed in Chapter II can also be
investigated.
- 162 -
-------
EVALUATION CRITERIA AND CONSTRAINTS OF ALTERNATIVE RESIDUAL WASTE HANDLING
AND DISPOSAL/REUSE PLANS
Guidelines for the development of overall 208 plans have indicated a
variety of considerations which must be addressed in the evaluation of
alternative plans (Ref. Vl-2). These considerations are noted in Table
VII-2. Guidelines for the preparation of environmental impact statements
for 208 plans have also been developed (Ref. VII-3). A review of these
guidelines and information presented in previous Chapters indicates that
four groups of factors; namely, economics, environmental effects, per-
formance, and feasibility, will be of major significance in the evaluation
and comparison of residual waste management alternatives. Table VII-3
indicates a sludge (residual waste) disposal evaluation matrix which con-
siders these factors.
Cost estimates included in the matrix can be developed objectively for
each sludge disposal alternative; non-monetary considerations listed are to
be rated descriptively, using terminology such as that suggested later in
this section together with whatever summary quantitative information can be
provided. In the remainder of this section, each of the evaluation para-
meters to be considered is elucidated, including typical concerns and
requirements of management of the 208 plan with regard to sludge handling
and disposal.
Economic factors of capital costs, operating costs, and reclamation
revenues are objective evaluations which can be made in a straightforward
manner for each sludge disposal alternative. The following sections
discuss the parameters mentioned above in more detail including typical
concerns and requirements of the management of the 208 plan with regard
to sludge handling and disposal.
Economic Parameters
Cost estimates of the residual waste disposal management alternatives
include capital costs, annual costs of borrowed funds, and the annual cost
of operating and maintaining the system. Credited against these costs
would be revenues from direct sale of secondary resources created by the
residual waste treatment and/or disposal processes. Reclaimed chemicals
such as recalcined lime, methane gas generated from anaerobic digesters
and used as a supplemental fuel source, heat generated from incinerators
and used for sludge drying or high-rate anaerobic digesters, digested
sludge used as a fertilizer or soil conditioner, and revenues from the sale
of crops grown on reclaimed lands are representative examples of such
revenues. All cost estimates would be compatible with the Federal Pollution
Control Act Amendments of 1972, Title 40 - Protection of the Environment,
Chapter 1, Part 35, Appendix A - Cost-Effectiveness Analysis. The guide-
lines furnished in the cost-effectiveness analysis relate to the definitions
of service life of land, structures, process equipment, and auxiliary equip-
ment and the elements of cost including the applicable discount rate to be
- 163 -
-------
TABLE VII-2
COSTS AND EFFECTS CONSIDERATIONS OF ALTERNATIVE AREAWIDE PLANS
Significant Effects
1. Water Quality Goals
a. Contribution to goals and objectives of the Act.
b. Contributions to other water-related goals of the planning area
2. Technical Reliability
a. Frequency of plant upsets
b. Frequency of spills
c. Frequency and effects of combined sewer overflows
d. Nonpoint source control
e. Regional availability of skilled manpower for treatment plant
operation and monitoring
3. Monetary Costs
a. Capital costs including discounted deferred costs
(1) public
(2) private
(3) total
b. Operation, Maintenance, and Replacement Costs
(1) public
(2) private
(3) total
c. Net revenue (public)
d. Overhead and plan management
- 164 -
-------
TABLE VII-2
(Continued)
e. Total average annual costs
(1) public
(2) private
(3) total
A. Environmental Effects
a. Hydrology (surface and groundwater)
(1) water quality
(2) water quantity
(3) water quality and quantity problems
(4) water uses
(5) flood hazards
b. Biology
(1) rare and endangered species
(2) wildlife habitats
c. Air quality
d. Land
(1) change in land uses
(2) land use planning and controls
(3) amount, type and intensity of growth (relate to 208 land
use plan)
(4) soil erosion damage
(5) significant environmentally sensitive areas
- 165 -
-------
TABLE VII-2
(Continued)
e. Wastewater management resources
(1) energy (power)
(2) chemicals
(3) land commitment for planned features
5. Social and Economic Effects
a. Population changes (5-, 10-, and 20-year projections)
b. Changes in economic activity where appropriate
(1) income per capita
(2) agriculture
(3) mining
(4) manufacturing
(5) services
c. Dislocation of individuals, businesses, or public services
d. Impact on other local, state, and federal projects having major
interaction with proposed water quality actions
e. Public health
f. Aesthetics
(1) recreational accessibility and activities
(2) unique archeological, historical, scientific, and cultural
areas
(3) noise pollution
6. Implementation Feasibility
a. Legal authority
- 166 -
-------
TABLE VII-2
(Continued)
b. Financial capacity
c. Practicability
d. Coordinative capacity
e. Public accountability
7. Public Acceptability
used in the evaluation and selection of alternatives (see Appendix A).
Additional economic considerations applicable to residual waste disposal
alternative selection are presented in Reference VII-2. Procedures for
calculating present worth and annual cost may be found in Reference VII-4.
Information regarding capital and operation and maintenance costs for
residual waste processing, transport, and ultimate disposal is noted in
Chapters IV, V, and VI of this report. This information, used in con-
junction with the sludge handling process matrix (see Figure VII-2), will
provide the planner with a means by which reasonable sludge handling and
disposal systems can be combined and evaluated on a cost-effective basis
using the guidelines referred to above.
The planning agency should also consider the regional economy and
indigenous resources of the area when considering such factors as cost of
labor, materials, fuels, transportation, and their availability within the
region. There should be joint plan review between the 208 planning agency
and existing regional agencies such as those acting as a clearinghouse
for the A-95 review process. This would prevent duplication of planning
efforts and provide an integration of urban growth and transportation
plans with the regional 208 plans. It is obvious that information on the
projected population growth, its characteristics and mix, and the trans-
portation systems to move the population and required resources will
greatly assist the 208 planning agency in determining the projected tax
base from which revenues could be derived for constructing, operating, and
monitoring residual waste disposal systems.
Environmental Parameters
The processing and disposal of residual wastes may influence environ-
mental quality in many ways and may generate secondary effects beyond the
- 167 -
-------
TABLE VII-3
ALTERNATIVES EVALUATION MATRIX
PARAMETERS
ECONOMICS
ENVIRONMENTAL
FACTORS
FEASIBILITY
PERFORMANCE
CAPITAL COST
ANNUAL CAPITAL
AMORTIZATION
0. AND M. COST
RECLAMATION
REVENUE
PRESENT WORTH
WATER QUALITY
AIR QUALITY
LAND QUALITY
FLORA AND FAUNA
AESTHETICS
PUBLIC HEALTH
COMMUNITY IMPACT
RESOURCE
CONSERVATION
FINANCIAL
FEASIBILITY
PUBLIC
ACCEPTABILITY
LAND USE
COMPATABILITY
EASE OF
IMPLEMENTATION
SYSTEM
EFFECTIVENESS
RELIABILITY
ADAPTABILITY
CALAMITY
RESISTANCE
PERMANENCE
ALTERNATIVE
RATING
ALTERNATIVE
RATING
ALTERNATIVE
RATING
ALTERNATIVE
RATING
- 168 -
-------
immediate receiving environment. Several major environmental factors such
as water, air, and land quality; biology; aesthetics; public health;
community impacts; and resource conservation have been investigated in
this report. The planner is referred to Chapter VI for an in-depth and
detailed evaluation of these factors for the various ultimate disposal
or reuse methods. The review of the environmental parameters discussed
here is broad, general, and intended to provide the planner with an over-
view of the major concerns within the environmental factors. Means of
implementing programs to address these concerns by the management agency
during the operation of the 208 plan programs are also highlighted.
Water
Evaluation of the effects of residual waste handling and disposal
should consider both fresh surface and ground water as well as marine
waters. Relative values of fresh versus marine waters are difficult to
establish. For all purposes short of potable water supplies, the two have
similar uses such as recreation, fisheries, and transportation. Indeed,
even for special coastal municipalities using or considering desalting of
saline waters to supply or augment potable waters, marine and fresh waters
both may serve as sources of potable water. In the preparation of 208
plans, the planning agency must provide coordination between water supply
and wastewater treatment agencies' plans to insure that disposal of residual
wastes from water treatment plants into municipal sewers does not adversely
affect wastewater treatment and vice versa. The planning agency should act
as a review body for water and wastewater treatment plans to insure com-
patibility and to promote and encourage joint-residual waste handling and
resource recovery projects. Power to act as a review body will preferably
be an expressed power enacted through enabling state legislation. Acting
as a plan review body, the agency could (1) encourage the water supply
agencies to actively pursue programs to reduce household water consumption
through pricing mechanisms and plumbing code revisions, (2) encourage
installation of water-saving devices (e.g., pressure-reducing valves,
shallow-trap toilets, flow-restricting showerheads, and others), and (3)
encourage adoption of wastewater treatment technologies which produce less
residual wastes in the treatment process. Likewise, the agency could
encourage combining water treatment plant residual wastes with wastewaters
for further processing and disposal in wastewater treatment facilities if
it were technologically feasible and environmentally sound.
Obviously, the planning agency must insure that the 208 plans developed
will meet existing Federal and State standards for water quality. Where
state standards do not directly address residual waste processing, handling,
and disposal with regard to the protection of state waters, the management
agency should either seek to possess statutory authority to promulgate and
enforce such standards or provide mechanisms of coordination with other
state agencies promulgating and enforcing such standards. A mechanism for
coordination which may be used is a permit system administered by the manage-
ment agency for constructing, operating, and/or monitoring residual waste
- 169 -
-------
treatment, transport, and disposal systems which allows state or local
agencies concerned with public health and sanitation, water quality, and
transportation safety and comment on and review for approval applications
for such permits.
Air
The handling and treatment of residual wastes can result in volatili-
zation of compounds to the atmosphere and even possible direct discharge to
the atmosphere via off-gases from incinerators, anaerobic digesters, and
recalcination kilns. It is also possible for the residual waste disposal
site to present problems of air pollution such as gas generation from sani-
tary landfills and wind-blown aerosols from land reclamation/sludge recy-
cling projects. As with the protection of the aquatic environment, the
management agency should seek authority to promulgate and enforce air
quality or emissions standards specific to residual waste handling and dis-
posal if such standards do not already exist. Likewise, the managemer.L.
agency may provide through a permit system the approval of local and state
agencies responsible for maintaining and monitoring air quality. Air
quality is measured by standard parameters such as particulates, sulfur
dioxide, and oxides of nitrogen and, as such, both the degree of intensity
and extent of the affected area for these parameters must be considered in
the alternative evaluations.
Land
Protection of land quality goes beyond the protection of land
fertility and the growth of acceptable crops. If the method of disposal
or reclamation of residual wastes involves land application, nearby land
use and growth patterns must be protected and assured. Local, areawide,
and State agencies concerned with land development and urban/rural growth
plans should play an active part in the preparation of regional ultimate
disposal and land reclamation/sludge recycle plans, from identification of
suitable land sites to assistance in developing appropriate monitoring
program and permitting procedures. Condemnation rights and legal lia-
bility for incoming and outgoing transport systems such as pipelines and
rail and truck routes must be assured either by the management agency itself
or in cooperation with local agencies. As with all other disposal sites,
sanitary landfills accepting residual wastes or projects involving land
reclamation/sludge recycling must provide controlled access to only properly
authorized personnel. Where projects involving the growing and selling of
crops on reclaimed lands using sludges from municipal wastewater treatment
plants are proposed by the planning agency, the management agency should
require approval by the various agricultural and public health departments
before permitting the growth of food crops. If the regional planning agency
proposes to sell residual wastes to the nearby farming community for use as
a fertilizer or soil conditioner, the management agency must assure,
possibly through a permit system, that the farm operation uses the residual
wastes under proper health conditions.
- 170 -
-------
Flora and Fauna
Flora and fauna are inextricably linked through various tropic
levels in all ecosystems. Areas of concern include trees, shrubs, grasses,
crops, aquatic plants, endangered species, birds, land and water animals,
and insects. A particular sludge disposal alternative may affect, either
beneficially or adversely, any or all of these elements. Species diversity
and population within that species, both with and without a particular
sludge management alternative, must be considered by the planning agency.
Aesthetics
Aesthetics standards are largely results of prior exposure and con-
ditioning, varying widely between individuals. Visual and auditory
clarity and composition impact upon one's perception of a "clean and
enjoyable" environment. Architectural design to blend with local surround-
ings and noise levels, particularly in transport and disposal must be con-
sidered and adverse impacts kept to a minimum.
Public Health
Public health aspects of a sludge disposal alternative consider the
risks of transmission of diseases or toxic substances to the public. Many
of the concerns in this area are included in the evaluation of water, land,
and air quality. Additional concerns may also include insect or rodent
infestation through the use of a particular sludge disposal alternative or
the protection of workers under adverse or potentially dangerous working
conditions.
Community Impact
Communities may be affected in a variety of ways under different
sludge disposal alternatives. For example, removal of an ineffective
sludge handling procedure in a community wastewater treatment facility
and consolidation in a central treatment plant may enhance outlying
community property values. However, added truck traffic with its accom-
panying noise, dust, and exhaust emissions may place undue strains upon
local street traffic and visually impair local atmosphere and harmony.
Resource Conservation
Resource conservation recognizes the need to preserve limited and
diminishing resources. Alternatives which may not be more economical but
do provide resource reclamation may be chosen by the public, albeit at a
higher cost (premium) for the very fact of resource reclamation. Short-
term impacts such as higher costs must be weighed against the long-term
effects of conserving limited resources.
- 171 -
-------
Table VII-A provides the planner with a means of assessing the
relative impacts of alternative residual waste plans upon the factors
discussed above.
Feasibility Parameters
Financial Feasibility
It is probable that future sludge handling and disposal systems will
involve greater costs, both capital and operating, than previous systems.
If the alternative system imposes too high a financial burden upon the
management agency, then the alternative is not feasible. It is recognized
that different sludge management systems may be eligible for different
portions of Federal, State, and local funding. Therefore, the grant
eligibility of the system as a whole will help determine its overall
rating. Likewise, a larger portion required of local funding may place
strains upon local governments' ability to raise the necessary revenues.
The management agency will have statutory authority to accept and
manage Federal and State grant monies, raise revenues, and incur short-
and long-term indebtedness. If the agency were to consider assuming the
financial responsibilities of constructing, operating, and monitoring
various regional disposal sites, it should also have powers to finance
general obligation bonds or system-user charges sufficient to recover the
costs incurred. Such financial power would then serve as a control
mechanism in combination with standards promulgated by the agency pertain-
ing to types, volumes, and characteristics of residual wastes to be
handled and disposed by the agency. If local areas or municipalities are
allowed to construct, operate, and monitor disposal sites or land reclama-
tion/sludge recycling projects, surety bonds could be required by the
management agency to insure adherence to standards and regulations and
that, upon abandonment of the site or completion of land reclamation, the
site would be available for productive and safe community use.
Public Acceptability
Strong opposition at a local level may arise due to potential increases
in water and sewer rates or special assessments. An effective public educa-
tion program would then be necessary to insure implementation of the
selected alternative. Likewise, this public education process, particularly
during the 208 plan review process called for in the 208 guidelines
(Ref. VII-2), will provide a forum in which public attitudes, if adverse to
sludge handling and disposal alternatives proposed by the planning agency,
can be modified by an in-depth review of the benefits accruing to the public
by adoption of the preferred plan.
- 172 -
-------
M
W
CO
o
n
f-l
w
•C
(H
CO
U
^
^
tH
M
»J
<2
jS
cy
Q
2
<5
t-J
S**
EH
M
1
O*
Pi
M
O
CO H
CU CX
O "O
IH C
tx cd
g
•rl CO
Ol
^ *H
rH 4J 01
4J -H rl
CO rH 3
01 Cd 4-1
IH 3 3
O cr m
1
o
l-l CO
tx G
o
H TH
iH 4-1
o tx
CO O
CO CU
U CO
co 3
to
Xl -H
CO 4J
4-1 CJ
O 3
£5 *O
1
c
IH iH
i-l
CO 13
G
01 cd
13
•H >>
3 *~4
1 4J
G 0
•H 0)
0] l->
CO iH
XI 13
CO - f-
01 XrH
> 4-1 4-1
U rH 0)
tx cd M
B 3 TH
M cr -U
01
a c
•rl -rl
M
4J td
C B
OJ
S n
o o
r>
o »c
l-i co
CX 01
B rl
•H 14H
gnificant
1 waters,
TH rH
CO Cd
CO
rH 0
•H iH
O 4J
CO tX
O
CO
01 01
CO CO
td 3
01
I-, -O
0 G
G cd
•H
^
>\ 4-1
rH IH
•H >
M iH
cd 4-1
u cj
0 3
CX T3
E 0
Ol l-i
H tX
rH
cd i
CJ 3
0 rH
rH rH
O
CO CX
p
01 IJ
3 TH
o cd
rH
4-1
>» CO
rH O
rH B
cd
•H MH
4-1 0
G
cd co
CO CU 40
XI > G
3 0) cd
n rH 4-1
^,
4J
•H
rH
cd
3
cr
CJ CO
•H td
4-1 01
Ol M
f! CO
4J
0) 13
Ol 01
CO N
•H
CO rH
cu to
4J CJ
O O
B rH
0
M G
ft, -H
tH
CO 1
O 3
O rH
rH rH
0
CO CX
i-i
01 M
3 TH
O CO
rH
Ol
rH O
rH CO
CO
•H »4H
4-1 O
C
CO CO
CO CU 4-1
XI > G
3 0) CO
CO rH 4J
f*.
1 4J
S -rl
•3 iH
CO
13 3
Ol cr
N
TH rl
rH 01
tO 4-1
O CO
o 3
rH
c!
gnificant
ovement i
•H U
on ex
^
4J
•H
•rl
4-1
O
3
13
O
Jj
O.
rH CO
•H G
0 0
CO -H
4J
co tx
Ol O
CO
id oi
Ol CO
IH 3
CJ
C! IH
M O
4J
pj
01
CO
CU CO
M 01
CX -H
4J
X! iH
4-1 i-H
iH Id
3 3
cr
cu
rH CJ
Xl -H
•H 4J
4J CU
cd x:
(X 4J
B 01
O 01
o id
CO
01
co
co
cu
IH CO
O 4-1
01 c
•O CO
4J
4-1 3
XI rH
60 rH
•H O
rH 0.
CO
M
G TH
•H cd
co oi
4J B
rH O
3 CO
CO
Ol G
& -H
4-1
4J iH
X; rH
60 CO
•H 3
rH CT
CO
^J
CO CU
4J
01 CO
cu 3
co
3 G
cd TH
CJ
directly
provement
c 0
I-H TH
4-1
C
01
CO
0) X
l-l 4J
CXiH
r-l
C3 cd
•H 3
cr
co
01 O
M-H
d 4-1
id 01
fCt J"1!
O 4J
CO
O 01
S3 CO
^
4-1
•H
r-l
cd
3
cr
TJ
B
cd
rH
G
•H
CO
CU
60
G
cd
CJ
0
^
4J
•H
rH
cd
3
cr
M
•H
cd
G
iH
01
CU
60
G
id
X!
CJ
o
t|
01
4-1
CO
^*»
G
CO
G
•rl
co
01
Ml
CO 4J
x; -H
CJ rH
CO
O 3
55 cr
0)
01
CO
cd
0)
M
o
G
•H
4-1
4-1 CO
X! 3
60 TO
•H
rH M
CO O
CO CO
01 M
CJ O
3 "d
•o o
o
>-> G
0, -H
4J
60
•H
rH
co
CO
01
CO
3
CO
CJ
directly
gradation
B 01
M -O
CJ
•H rH
4J CO
01 CJ
JS O
•U rH
CO
01 0)
CO S
O
H-l CO
o
G
G TH
o
•H CO
4-1 01
CO -H
T3 4-1
10 TH CO
M rH C(
60 CO 01
01 3 IH
O cr cd
^
4-1
•H
•H
4-1
U
3
•a
0
M
tx
rH CO
•H G
o o
CO TH
4-1
CO CX
01 O
ca
cd ai
o) ca
o
0) IH
a o
1
a
TH kl
•rl
rH CO
CO
•H tH
4J tO
CO 01
CO 01
XI CO
3
co C 01
TH 4-1
ca G
01 CO td
o oi 4-1
3 CO 3
13 CO rH
O 01 rH
IH U O
PL, CJ P
G
•H
13
01
•o
CO
M
60
01
•O CO
CO
X 01
4-1 rl
•H CO
§*o
01
cr -N
TH
M rH
CU CO
4J U
CO O
EC rH
|
•H
iH
X! Cd
4-1 3
•H cr
o
ca TH
10 4J
oi 01
CO 4J
CO
<4H 01
o cd
CO 01
CO rH
0 Xi
rH Id
M
01 -rl CO
B co 01
O 01 -H
C/3 13 4-1
CO
B
O
•H
4-1
CX
H 0
•H
O Ol
co co
3
01
4J 13
•H B
B CO
•H
4-1
rH >
01 TH
4J 4-1
CO CJ
S 3
i-t 13
4J O
tH l-l
:=> (x
co
CU
•O
cd
l-l
60 X
0) 4-1
•O TH
rH
>, cd
rH 3
4-1 D*
G
CO IH
CJ TH
•H cd
<4H
•H rH
B cd
60 CJ
•H O
CO iH
>4H
O
CJ
O CO
•H M
4J 0)
Cd 4-1
13 CO
cd 3
60 01
Ol B
M
bstantial
esh or ma
3 rl
CO *4H
CO
13
4-1 CO
•H -a
3 G
rd
01 4J
rH CO
XI
•H CJ
4-1 iH
rd 4-1
cx cu
B Xi
O 4J
cj ca
B 0)
•H td
X »rj
rH 01
rH M
rd -H
4-1 CO
O 01
H 13
rH
•H 1
O CX
CO O
co oi
4-1 CO
•H 3
B
•H 13
iH B
CO
rH X
rH 4-1
CO iH
•H >
4-1 TH
B 4J
cd o
4-1 3 CO
CO 13 G
XI O O
3 H -H
co ex 4J
^i
•rl
cd
0)
•a
TH
i
•H
CO
cd
x>
CO
01 >>
•a 4J
id TH
l-l rH
60 CO
01 3
a cr
<4H CO
O 01
B rH
O P.
•H CX
4J 3
CO CO
13
CO M
P Ol
60 4-1
a> co
13 3
01 01
B -H
01 Xl
M cd
4J 4-1
x o
M tX
- 173 -
-------
•a
cu
3
•H
4J
B
O
U
S5
0
M
H
^
c£
W
CO
S5
O
o
H
O
£3
o
CO
a
H
U
a.
s?
M
£•*
£_<
M
2*
5
y
§
0
o
PS
£^
jj
2
W
P3
CJ
M
M
04
o>
60 1
•O 0)
3 M
rH
CO rH
R)
U-l 1-1
O 3
4-1
0> CO
CO B
3
U-l
rH O
CO
•rl CU
U 60
•H (0
U-l CO
0) 3
B
oi co
43 0)
O CO
CO 3 CU
o) -a cj
4-1 CU ^J
O rl 3
B O
O T3 CO
rl B 01
0-< cd \-t
4J
B
CJ
fj
0
1-1
•H
^
c
cu
01
cu
o
a.
£
iH
^
W 1-.'
O T-l
B
(0 3
01 g
4J B
0 0
B 0
0
h UH
CM o
O
U
4-1
CO
01
rl
43
4J
CO
O
CJ
3
•a
0)
t^
X 43
rH 4J
rH rH
CO CO
•H 01
4J 43
B
CO O
4J TH
CO rH
43 _D
3 3
CO CX
X
4-1
•H
B
3
D
O
U
B
TH
cu
01
CO CO
cu cu
rl 3
CJ rH
B co
•ri >
co x
01 4J
CJ rl
3 0)
•0 CX
0 0
rl rl
U-l
O rH
CO
oi ca
60 O
CO CX
01 01
3 TH
•a
co
CU 01
CJ 60
3 T3
•0 3
0) rH
l-i CO
X rl
rH O
CO
•H CO
4J 0>
B CJ
CO 1-1
4J 3
01 O
43 CO
3 cu
co IH
0
•H
rH
43
3
CX
O
4-1
B
a)
43
UH
O
rH
a)
•H
4J
B
01
4J
0
CX
co
0) 43
CJ 4J
3 rH
•a co
0) 01
CA 43
X
4J
•H
UH B
0 3
CO I
4J 5
CJ U
01
UH B
UH IH
01
B
01 0
O TH
B 4J
at co
co 3
TH 4J
3 -H
B co
co 4J
01 C
U 0)
3 co
•O 01
01 l-i
fvj CX
co I
01 0)
y M
M
3 ^"i
O P
ca co
cu -a
rl B
o
X CJ
M CU
CD 01
B
Tt B
M TH B
CX O
01 -H
rl CO 4-1
CU OJ U
3 rl 3
CUCJ^
UH B 0
•H rl
CO O
0) O
B B 0)
3 CJ
CO 43 rl
B 4J 3
O -H O
O S CO
^
60
M
01
B
01 0)
60
UH (0
O CO
3
rH
0) CU
> 0
0) rl
rH 3
O
4J CO
B cu
0) M
CO
0) CO
M rH
CX CO
TH
01 M
B 0)
•H 4J
CO co
4-1 E
B
•H *O
CO B
X co
i-H
at
CJ
•H
CO
43 X
CU 1 '
tH
rl B
O 3
•H i
CO 0
•H O
CJ
0 01
CO 43
4J
B
•ri UH
0
0)
60 CO
B 4J
CO B
43 0)
U B
0)
O rH
S3 0)
43
4-1
rH
01
01
43
o
•ri
rH
3
CX
B
•ri 4J
B
0) 0)
60 S
B 0)
CO >
43 rH
CJ O
O B
Z TH
B
•H
ca
rH
0)
0)
f_H
rl
0
•a
o
M
O
CU
co
•ri
0
c
co X
a) 4J
CO -H
cO B
0) 3
rl B
B!
M O
o
**
B
CO
UH
o
rH
at
•ri
4-1
pj
•01
4-1 43
O 4J
CXrH
at
co CD
01 43
CO
CO O
o) T:
U rH
0 43
B 3
M CX
^,
1 rl
B CO
o -a
O B
o
0) U
U 0)
rl CO
3
o co
CO 0)
0) CO
rl 0) B
OJ o
X rl TH
rl CJ 4J
at o) cj
B -0 3
•ri T3
rl T3 O
CX B rl
co a
co
0) B 0)
CO O 0
CO TH tl
0) 4J 3
l-i CX O
CJ B co
E 3 0)
M CO rl
M 4J
0 TH
B
O 3
•H g
UH E
UH O
a) o
rl
U B
•ri
co
a) co
CO 0)
at 3
0) rH
H CO
0 >
B
•ri X
4J
X rl
rH 0)
rH CX
CO O
•ri rl
4-1 CX
B
CO CO
4-1 rl
CO CU
II
1
CJ
3
•o
0
UH IH
O CX
co x
0) rl
•ri CO
4J -a
•ri B
4J O
B CJ
CO 01
3 ca
o
rl B
0)
4j r\
at 4J
0) TH
rl 3
00
ca
co cu
cu cj
B rl
3 3
co o B
B ca c
O 0) iH
CJ rl 4J>
CO
4J
B
0)
•o
•ri
co
0)
rl
UH
o
4J
B
0)
1
CJ
cd
rH X
CO TH
•ri B
-0 3
ca B
0) O
> U
r-t
o a
> 0
B M
0
w
4J
ct)
0)
43
4J
CO
0)
CO
at
0)
rl
CJ
B 43
•ri 4-1
rH
X at
rH CU
0) 43
•H CJ
4J TH
•ri rH
CO 43
0 3
CM CX
- 174 -
-------
Land Use Compatibility
Land use compatibility insures compliance with existing and future
land use plans. The alternative evaluations must consider preservation of
open spaces, areas of scenic beauty, flood plain usage, zoning ordinances,
and use of buffer zones around treatment systems and land disposal/recycle
areas. The investigation of land use compatibility must be addressed
thoroughly in the plan review process, particularly under the environmental
factor of quality.
Ease of Implementation
The ease of implementation considers the degree of difficulty in
working within current and projected legislative mandates and regulations.
Major reorganization of existing agencies including their responsibilities
as well as requirements for additional legislative and regulatory powers
will severely hamper the utility of a sludge management alternative.
As mentioned under public acceptability, necessary changes in local
ordinances or State legislation to allow implementation of the preferred
sludge handling and disposal option will be partly accomplished by provid-
ing to the public, and hence to elected local and State officials, the
sound rational for the required changes. The management agency, during
the 208 plan implementation process, may also be given authority to appear
before the requisite local and State agencies to request changes in
ordinances or regulations governing sludge handling and disposal management.
The ease with which these change processes can and will occur must be con-
sidered during the planning process.
Table VII-5 provides the planner with a means of assessing the relative
impacts of alternative residual waste plans upon the feasibility parameters
discussed above.
Performance Parameters
Effectiveness and Reliability
A residual waste treatment and disposal system must be reliable,
adaptable and provide resistance against calamity and failure. The
reliability of a residual waste treatment and disposal system varies
depending upon the processes employed. For example, a stable aerobic
sludge digestion process has a higher reliability than anaerobic digestion
which is subject to longer-term upsets and associated down times from
toxic materials or poor process control. Similarly, complex mechanical
treatment systems such as wet air oxidation have an inherently lower
reliability than digestion processes because of greater stresses on the
components of the process and a higher probability of mechanical failure.
Systems with duplicate components on standby may provide greater reliability
but will suffer in an economic comparison with other systems possibly not as
reliable. Relatively new and untried processes such as pyrolysis would
- 175 -
-------
co
(d
H
CO
o
CO
O
in
t
H
W
SH
|_H)
M
H
^
H
p .
5
O
U
H
CO
Q
g
* C TH
xi TH s
XI iH
4-1 CO tH
C HI 4J
01 -H (0
6 0 rH
01
0 Xi
4-1
^
XI MH
O
•o
0) >,
tJ 4J
TH -H
co u
01 O
Q i->
1 C
•U 0
C (X
3 «
HH O)
M
G
•rl <4-l
x: o
•H CO
3 01
•H
CO 4J
rH TH ^
rH rH O
CO -H C
<4-l XI 01
n) of
^* CX CO
r4. CO
iH O Ol
•O rH
CO 60X1
41 C -rl
Ptf tH CO
rH
o
o
rH
X
XI
13
01
4J
o
CX
3
CO
^
rH
oo co
C 0.
0 3
V4 O
CO 00
•a
G
CO
C
CO
rH
(X
01
B
o
CO CO
Ol
Ol 00
M C
•H CO
3 X!
cr o
0)
^4 00
PJ
i-H -H
rH C
•H O
S N
rH
CO
O
O
rH
0)
B
o
to
^,
XI
T3
01
4J
M CO
O CX
ex 3
!X O
3 >-l
CO 00
CO
0)
00
c:
CO
x; co
CJ 4-1
•H
M 3
0 TH
C rH
•H
B o>
>
0) TH
M 4J
•H CO
3 rH
cr co
CU iH
t-i 00
CU
rH rH
rH
TH C
S -H
•o
M
CO
o
4J
4J
t3
CU
rH
CO
^H p
XI 0)
CO CO
^
o co
•H
rH CO
XI TH
3 XI
PH ^ J
C *M
TH O
XJ
4-1 «
•H 0)
S -H >
4J O
0) -H C
rH rH CU
rH tH CX
fl) XI co
>4H CO
CX CU
>. CO rH
rH O Xl
rH -H
CO 00 CO
c c c
•rt TH O
OOTS O
V< C co
« 3 0)
X OH M
rH
CO CO
•rl O1
4-1 00
c e
CO CO
4J X
co cj
XI
3 00
CO C
TH
(U C
M O
•H N
3 .
CT* T3
Ol C
M CO
rH C
rH nJ
•H rH
S O.
1
c
CO
00
O
CU
l-l
IH en
O Ol
•H o
B C
01
01 00
M tO
•H
3 IK
cr o
01
M C
o
rH 4-1
•H CO
IS N
rH
CD
CJ
O
i-H
CU
s
0
co
^
XI
•a
(U CO
co ex
O 3
ex o
ex P
o oo
co
01
00
C
CO
X! CO
O 4J
•H
rl B
O -rl
T-I i-H
CO
B Ol
>
CU TH
^j 4J
•H CO
3 rH
cr co
01 .
>J U)
01
i-H
•H C
3 -H
,
C
CO
00
rl
O
Ol
u co
O CU
•r-)TH
CO CJ
B C
CU
CU CO
I-i cO
•H
3 <4H
cr o
Ol
M C
o
rH 4J
•H cO
3 N
rH
CO
O
O
i-H
^
XI
0)
CO
0
CX
CX
o
^^
rH
00 CO
C (X
0 3
V4 O
4-1 rl
CO 00
X!
4-1
TH
3
'01
rH
XI
•H
4J
R)
ex to
B C
O co
O rH
C CX
•H
01
>% to
rH 3
rH
CO -0
4J C
O CO
H •-!
C
o
0) 00
XI G
•H
CO 00
4J p
iH tO
B x:
•H U
rH
MH
i-H O
CO
00 >,
CU 4-1
rH TH
rH
CO TH
•a xi to
CU -H 4-1
o o> e
X O T-l
cd ex i-i
i
g
00
c
iH
e o
r-i TH
0) rH
X! X>
en
a>
> 01
0 X!
4-1
^^
ft <4H
O
•c
0) >,
U) 4-1
0 iH
CX I-i
CX O
O T->
x>
4) rH
rH CO
XI 0
a o
4J rH
O T3
cx e
CX O
rj ^^
SO!
^rj
3
•o
C cd
•H
O ca
G 4J CO
Rl C C
C R) CO
T-I M ai
Pu 60 H
- 176 -
-------
receive subjectively a lower rating on reliability since performance data
have not been developed on large-scale operating systems.
Adaptability
The severity of system disruption must be considered in the evalua-
tion of sludge disposal alternatives. For example, a break in a sludge
pipeline carrying digested sludge to a land disposal system may cause
serious, yet localized environmental damage. Alternative transportation
such as by truck must be available if the central sludge treatment system
does not have storage capacity (i.e., time) sufficient to allow time for
pipeline repair. Capability at or near the ultimate disposal site for
residual waste storage during down times may also provide an additional
alternative.
Calamity Resistance and Performance
It is reasonable to expect that population and environmental changes
and developing new processing techniques may result in changed and possibly
more restrictive performance criteria. Therefore, a residual waste pro-
cessing and ultimate disposal system must be able to accommodate possible
altered performance and monitoring criteria. In addition, unexpected
events such as floods, earthquakes, high winds, and labor disputes can
adversely affect an overall residual waste disposal system. The planning
agency must provide means by which the disposal system can withstand such
events by providing proper long-range planning, design and operating
standards, and alternative contingency handling and disposal plans.
Table VII-6 indicates, for those processes shown in Figure VII-2,
factors of performance normally considered in selection of wastewater
treatment and sludge handling unit processes. A greater degree of these
processes and their alternatives is presented in Chapter IV.
Table VII-7 provides the planner with a means of assessing the relative
impacts of alternative residual waste plans upon the performance factors
discussed above.
- 177 -
-------
fc
i
<
I
tf.
O
y.
C
w
c
c/J
M
0
w
to
o
u
S
^
o
z
M
H
Q
_
i
M
£3
i
Pu
W
in
U
PH
H
M
SC
U
2
_I
2
O
W
g
V)
<1
M
U
£-3
* £
c:
o
"* *0
ft*
•H
C
•S -5
W (0
(X N
3 (0
U 33
U
O
•4 V
C £
U-< O A
0 -H C
V at u
0) LJ £
M 01 -rt
W O. «
0 3G
>s A
•H t-t W O
•J -H 0
os ca o D-
•*
T-( C 41 «r*
«H a 3 I-H
< o c c-
*-* M
a> o
«?^
•H (0 «J
•-t X 41
A O C
U
01 -H
ID W
V* X t/) t/J PJ «< •<
C C
o
•H * (ft
« (0 V) Q 4> U U
Mb U ^ « U U
O O IIIO 1 O 1 33 P
"O T3 -O 13 .O T3 "O
0 O O 0 D 0 0
DM M
U 04 P.
« n a
« ft) ai « « i= c we n
U *J ij O U 03 M OB U
•r^U (Jt-t^-*O«O 1 -H O -H
E3 SBSi-Htnt-) B-H 0
j: 4-» u^^K x" A K XJC
t_) C/l IO U O tJJ W U *-4 WO
•a -o
0 O
o o
*O° -^"O-H.^ *o u "Q ^3 £
o x o o >
•O t) -O *O
o o o o
o o o o
"OUO 13TJUT3 T3 P -O O "O
O CO OOv4Q O
o x >, oo>\o o a o x o
U M t-i OO^«tJ O U« IJ M O
> > > >
ZEE tSXS X Z X Z S
0 *0
0 0
O -H O O -H O O -H 0 O
O>^(0 O >i O *0 O O >
M T3 -O M 13 T3 W t) 13 Li ki Li
•H O O -HOO-H O 0 -H -H >r4
woo aioooi o o « a «
U- O O tt, O U tn U U bu ft. tn
M •-(
* -H *«
v t N tttv i ,e H-* t t i
41 00 C
41 i-t iH
£ EC «
•aCX -OCX-O K* X C C "O
,0-^nJ O-HtCO 4 (0 -H -H O
3u Z 3C ££X!K £ 3C 1C £ X
u
C
e
S
U H
00
D) *O tO 4j U
^^^3^-H^BC O
ffl o in «d o ^a e -H
c ** c -^t *-> no w
H^ £ 2 ! !f * "S M -S
• CLJ 41 V) *J fH
5e»* wcwow ca o
. o -H y o — * i 4> a b c 4)
OSH
E
V
4J
fH
«
4>
£
W
O
4J
U
41
«M
4)
Lt
V
<
• 2
§2
S..
°u
H
« S
1 z
- 178 -
-------
H
co
C
V.
a
o
_!
M
O
P-,
CO
H
a
i
M
M
OS
i
W
U
a
w
t5
, 0 CO
co u-i E
B -
•H 01
Ai CJ
00 CO 4-1
B 3 CU
•H cr
B x: •
O 4-1 CU
•H P 4-1
4-1 CO 3
o cu o.
E B
u-i o T;
X 4-1 VJ
rH B 0
rH CU XI
3 > CO
d« CU r-
O 1
4-1 P
cu
4-1 CX
a co
OJ P 1-
T3 O P
CO CU
CO 4-1
>> CU -H
rH CO P
IH CO CJ
•a cu
to cj cu
cu o o
P P B
CX co
iH CU O
S B UH
^
rH
XI
(0 CU
iH X!
rH 4-1
CU
P U-l
Q
4-1
O B
U-i CU
P O
cu p
cx cu
cx
rH CU
rH 0 E
•H O iH
3 iH 4-1
CO
•a -H
CU P
cu cu
CJ 4J
X iH
CU p
CJ
rH CU
4-> O
CO B
CU CO
P S
60 P
O
rH U-l
rH p
•H CU
S CX
XI
4-1 rH
•H CO
3 CJ
•H
E C
CU CO
4-i x:
CO CJ
s>> cu
co E cu
£2
CU CU IH
rH rH 4-1
a. 4-1 B
E 4-1 3
•H -H O
CO rH tj
1 >•
CJ rH
a B
3 0
U-l
CU
>•, p
rH iH
rH 3
3 CT
UH CU ul
P P
B -H
•H -a co
CO B ft
E 10 cu
CU P
P rH
CO P
rH B O
rH 0 B
iH -rl -r
3 4-> E
X!
4-1
•H rH
3 <0
CJ
g-H
B
4-1 CO
CO X:
>-, CJ
CO CU
E cu
X E
CU CU iH
rH rH 4-1
O. 4-1 B
0 -H O
O rH -O
I
P CO
0 C P
V4H iH CU
P 4-1
CU 10 CU
D. -rl E
P CO
TJ CU p
CU 4-1 rg
cu -H a
CJ P
X CJ rH
•H <0 CU
3 B co
1
CU p
B cj
0
CO CU
u
o B
jj co
d
4J P
CX O
(d IM
T3 P
a) ca
CX CO
rH 1H
rH 3 P
•tH CU CU
3 C 4J
14
D 00
UH B
•H
CU B
4-* B
co <0
3 rH
rr cx
cu
•o cu
CO 4-1
W E
B -H 0
CU -O N
4-1 CU -H
ca E i-
r*> C C
co -H x:
CU
E P
iH iH
B 3
•H cr
B < E
CO p iH
CO CU 4-1
cu >
O UH
CO 0
rH
rH P TJ
•HOC
3 UH iH
B
CU
> 1
O CO
p p
cx cu
B 9.
3 0
§03
,_!
4-1 CO
CO 0
>-, CO
ca i
rH
CU rH
•H 3
CXUH B
B 0
•H B iH
CO iH 4J
•a
cu
4-1 CO
CO E
P CU
4-1 4-1 rH
CO B XI
C CU O
O 3 P
E cr D
cu E
*o n) co
X x:
CO O
CO O CU
X w E
cd
CO
4-1 iH
CU P
0) (U
e *->
•H
O P
4-1 CJ
r-l p
•rl O
R) B
U-i iH
B
r-l
H CU
rH
CO
B P
O CU
•H >
4-1 CU
O CO
B
3 B
UH n)
CU 4-1
CO
to CU
CU P
O O
B
rH CO
rH P >-,
•H O K
rH
CO
- p
CU CU
P >
3 CU
ca co
<0
CU P ^
B 0 rH
UH B
E o
•rt CU
P rH CO
CU XI P
4-1 co n)
B co cu
M 3 >i
-o
B
* CO CO
>-. p
4J B -H
•H O as
B iH a
tO 4-J CU
rH 0 P
CO B
0 3 P
UH O
UH -r-
O CU CO
co e
4-1 CO
B cu cu
cu a p
r* 1"
01 rH 3
rH CT
B -rl CU
M 3 P
CU 1
B P
o
O UH
4-1 P
cu
4-1 p. n)
CX -H
CO P P
T3 O CU
CO 4-J
CO -H
4-1 CU p
O CO O
B co
CU CU
rH CJ O
rH O B
•H P a)
Sag
cu
rH
1 n)
B CJ
3 CO
1
E rH
CU rH
4-1 3
CO UH
CC? B E
•H O
X iH
CU B 4-1
rH CU CO
CX > P
E o cu
o P a
0 CX 0
1
4J
cu
1 CU
4-1 UH
CO O
XI
3 4J CO
CO P iH
O P
•H x: cu
rH CO 4-1
flj iH
UH ^ p
rH CJ
rH rH
I-H n! ac
•H iH E
3 4J iH
- 179 -
-------
CHAPTER VII
REFERENCES
VII-1 A Guide to the Selection of Cost-Effactive Wastewater Treatment
Systems, prepared by Bechtel Incorporated, for the U. S.
Environmental Protection Agency, Contract No. 68-01-0973
(May 1973).
VII-2 Draft Guidelines for Areawide Waste Management Planning for
Section 208 of the Federal Water Pollution Control Act Amend-
ments of 1972, U. S. Environmental Protection Agency (October
1974).
"II-3 Manual for Preparation of Environmental Impact Statements for
Wastewater Treatment Works,Facilities Plans, and 208 Areawide
Waste Treatment Management Plans, Office of Federal Activities,
U. S. Environmental Protection Agency (July 1974).
VII-4 Guidance for Facilities Planning, U. S. Environmental Protection
Agency (January 1974).
- 180 -
-------
CHAPTER VIII
MANAGEMENT OF A CONTROL AND MONITORING PROGRAM
INTRODUCTION
Following adoption of a 208 plan which includes a residual waste
control and monitoring program as specified by Sections 208(b)(2)(J),
208(b)(2)(K), and 208(c)(2), the 208 management agency must provide for
a coordinated control and monitoring program. Many of the concerns
that must be addressed by the management agency have been covered in
Chapter VII. In complying with Section 208(c)(2) of the Act, the legal
problems, institutional models, and regulatory mechanisms pertinent to
the management agency have been fully addressed elsewhere (Ref. VIII-1).
The purpose of the remaining sections of this chapter is to provide the
management agency with suggested elements of a control and monitoring
program for the ultimate disposal of residual wastes. The specifics of
these elements for each ultimate disposal method were discussed in
Chapter VI.
CONTROL PROGRAM
Depending on delegation or statutory powers of the control program,
adherence to regulations may be elicited through voluntary compliance
by persuasion (from proffering financial and/or technical assistance and
public pressure) or by direct legal requirement. In maintaining good
relations between the waste disposer and the management agency, persuasion
is most commonly employed with the possibility of public pressure and
legal action existing as a form of unarticulated intimidation. Utilization
of a particular disposal method may be governed by a permit and license
program, environmental (land, air, and water) quality standards, a land
use priority system, or purchase of disposal rights. More than one
regulatory technique can be used in conjunction to complement each
other.
Permit System
A permit is a written document granted by the management agency to
allow the permit holder to engage in a particular activity. While a fee
is usually assessed, the primary objective of the permit is to obligate
the holder to comply with stipulations which are regulatory in nature.
The stipulations assure:
(1) limiting the number of waste disposers utilizing a particular
method;
(2) regulating quality/quantity of disposed waste to insure little
infringemet upon beneficial use of natural resources;
- 181 -
-------
(3) compliance with monitoring and inspection requirements;
(A) obligation to waste pretreatment before disposal (depending on
quality/quantity characteristics of the waste);
(5) adequacy of waste conveyance; and
(6) competency of operator through requirement of operator licensing.
Given waste characteristics, the disposal site might be formally
classified to accept a particular waste. Thus, a permit may be granted to
dispose of a waste only at disposal sites of a certain class. If the
waste is changed in character after disposal has commenced, then a new
permit may be required. Permit stipulations might alter if conditions
change at the site or if new or significant data is revealed concerning
the site.
If non-compliance with permit stipulations occurs and the disposer
cannot immediately meet requirements, then a time schedule of compliance
may be designed. To insure that the schedule enables compliance at the
earliest date, the schedule is periodically reviewed and updated. When
significant violations of waste disposal requirements or prohibitions
are threatened or violations are occurring, have occurred, or will
probably continue to occur, a cease-and-desist order might be issued,
if the agency is so empowered. Legal action could result in suspension
or revocation of the permit, or a fine and even imprisonment may be
levied. Such punishment results from violation of permit stipulations,
negligence, incompetence, misconduct, or fraud and deceit in obtaining
the permit.
Environmental/Effluent Quality Standards
Various standards establish water, air, or land quality criteria that
define limits (usually upper limits) on amounts of physical/chemical/bio-
logical parameters. Water quality considerations are:
(1) receiving water standards (e.g., stream standards);
(2) effluent standards (effluent that is discharged to receiving
waters from the disposal site); and
(3) pretreatment standards (required of waste before utilizing a
particular disposal method).
Standards facilitate the attainment of goals regarding a clean environ-
ment by quantifying minimum quality of a clean environment. Quantified
stipulations as part of permit qualifications may directly reference
relevant standards. In addition to preserving general environmental
quality, standards maintain public health and aesthetic values.
- 182 -
-------
Receiving water standards are based on water quality requirements to
preserve beneficial uses of the water resource. Water may transport con-
taminants from a disposal site to contiguous receiving waters. By establish-
ing ar acceptable discharge loading from the disposal site, water quality
will be maintained commensurate with requirements of all water users
(utilization of water resources to receive effluent is a water use). The
acceptability of the discharge is determined by the carrying capacity of
the receiving waters and relative use of these waters within the matrix of
all users concerned. Because existing quality of receiving waters is the
result of more than one contributing source, defining the particular source
responsible for violating standards is difficult. Enforcement of standards
is based on an adequate surveillance program followed by agency investiga-
tion if the standards are violated and culminating in voluntary compliance
or legal action to reduce contamination from a particular source.
Effluent standards control quality/quantity of effluent water from
disposal sites. Standards are sufficiently high to insure that the overall
effect of all dischargers on the receiving waters will not infringe upon
beneficial uses of the water resource. Criteria can be revised and usually
made more stringent if the total number of dischargers increases, creating
a pollution problem. Even though stream standards are more efficient in
utilizing the full carrying capacity of the receiving waters, pinpointing a
standards violator is difficult for enforcement purposes. Effluent at the
point of discharge can be directly monitored to indicate violators. How-
ever, most disposal sites act as non-point dischargers (see Chapter VI for
details of disposal methods) which are difficult to control by any means,
including effluent standards. This is usually due to the existence of
variable loading magnitudes and the nondiscrete and possibly variable dis-
charge locations. Violation of effluent standards may be discerned by a
monitoring and surveillance program. Upon violation, enforcement may lead
to voluntary rectification or legal sanctions. The disposal facility may
undergo physical or operational modification, or the disposer may be
required to alter the incoming residual waste characteristics such that
violation will not occur.
Pretreatment of residual waste is to qualitatively/quantitatively
transform the waste to a state amenable to disposal by a particular
method (see Chapter IV for discussion of such transforms). A management
agency would require users of the disposal site to meet standards of
residual waste to be disposed. Such standards might be based on operating
limitations of the disposal method or on protection of off-site resources.
Pretreatment standards may be part of permit stipulations to dispose of
waste. Where a permit is granted for a specific, classified disposal site,
the standards apply to all of those particular permit holders equally.
Enforcement of pretreatment standards, based on monitoring and surveillance,
would lead to altering the waste to comply with standards or to cease and
desist disposing at the particular site.
- 183 -
-------
Land Use Regulation
By land use control, disposal of residual waste may be regulated by
prohibition to or allocation of an area for disposal purposes. This is
primarily a control mechanism used in urban or environmentally critical
areas, usually by means of a zoning code. Zoning codes deal with environ-
mental quality based on considerations of present and future public health,
safety, aesthetics, and general welfare of the community. Critical areas
controlled by zoning include shorelines and flood plains which are sus-
ceptible to flooding. While zoning codes generally specify what use may or
may not be made of a certain area, land use control can exist at a mor
diffuse level by specifying certain conditions that must be met in using
land in a particular manner. This control is exampled by soil conservation
districts which are concerned with prevention of soil erosion. Several of
the more common waste disposal methods are susceptible to soil erosion
(see Chapter VI for additional detail). In consideration of soil erosion,
authority exists to regulate construction operations, cultivation methods,
cropping programs, and denuding land (e.g., clearing). By possessing such
authority, a management agency concerned with control of residual waste
disposal can more easily deal with non-point discharges of contaminants.
Violations might be corrected by voluntary compliance or legal sanctions.
Disposal Charges
A form of control over waste disposal is to charge monetary payment
from users of a particular disposal site. Imposition of the charge would
be based primarily on quantity but could also include quality of the
residual waste to be disposed. Rather than being allowed to degrade the
environment by possessing the financial capability to pay any amount of
assessed charges, an upper boundary of waste loading may be established
with each user purchasing a loading allotment of the total. This program
is designed to induce the disposer to reduce his waste load output. Such
reduction is a significant objective in ultimate disposal of residual
waste.
MONITORING PROGRAM
A waste disposal site monitoring program is designed to provide
information concerning particular constituents of environmental quality.
This information is primarily used to indicate compliance with permit
stipulations, standards, and other regulatory statements, usually on a
comparative basis with background or initial conditions. Such feedback
includes inspection of the physical facility, operation and maintenance,
quality/quantity of loading, and characteristics of the disposal site and
adjacent environment.
- 184 -
-------
Monitoring the Constructed Facility and Operation
Monitoring the disposal structures and operation can be implemented
by:
(1) on-site surveillance; and
(2) requirement of written reports by disposal personnel.
On-site surveillance by a management agency requires that direct,
technically competent inspection of the facility be made on a periodic
or possibly random basis. This requires legal access to the disposal
facility and site. Such inspection would indicate:
(1) compliance with construction regulations;
(2) existence of adequate maintenance;
(3) order of written records;
(4) competence of operation;
(5) general compliance with permit stipulations and/or state
standards; and
(6) post-operative condition after shutdown.
Written reports by disposal personnel allows a less extensive monitoring
program by the management agency but demands a higher level of competency
of disposal employees. Greater assurance of accuracy and dependability
of the reports would be engendered by requiring an operator's license
of the responsible employee. These reports might address the following
items at specific points in time:
(1) completion stages of construction;
(2) documentation of impairment in operation;
(3) service and repair of equipment; and
(4) safety record.
Monitoring Parameters of Environmental Concern
Monitoring parameters of environmental concern include quantity/
quality aspects of physical, chemical, and biological components in:
(1) residual waste input;
(2) disposal site environment;
- 185 -
-------
(3) effluent from disposal site; and
(4) contiguous areas of critical concern.
Most monitoring is concerned with environmental parameters and requires
a greater expenditure of effort than surveillance of disposal structures
and operation. Both fields of monitoring can be implemented by management
agency personnel, disposal facility employees, or a combination of both.
Acc«ss to the disposal site by management personnel is essential. When
environmental data is collected by employees of the disposal facility
(including private contractors), submission of such information should
be through a certified laboratory. Most disposal facilities must also
directly deal with monitoring areas adjacent to the disposal site that
may be of critical concern.
Most parameters of environmental concern are monitored in response to
imposed regulations. These parameters include considerations of public
health, aesthetics, and community impact. Specific standards governing the
parameters may be present in granted permits in independent influent,
effluent, or receiving water standards. In addition to providing informa-
tion concerning fulfillment of legal obligations, monitoring of residual
waste input and the disposal site environment aids in operation of the
disposal facility.
- 186 -
-------
APPENDIX A
COST EFFECTIVENESS ANALYSIS GUIDELINES
(40 CFR 35 - APPENDIX A)
-------
-------
21639
Title 40—Protection of the Environment
CHAPTER I—ENVIRONMENTAL
PROTECTION AGENCY
SUBCHAPTER D—GRANTS
PART 35—STATE AND LOCAL
ASSISTANCE
Appendix A—Cost-Effectiveness Analysis
On July 3, 1973, notice was published
in the FEDERAL REGISTER that the En-
vironmental Protection Agency was pro-
posing guidelines on cost-effectiveness
analysis pursuant to section 212(2) (c) of
the Federal Water Pollution Act Amend-
ments of 1972 (the Act) to be published
as" appendix A to 40 CFR part 35.
Written comments on the proposed
rulemaking were invited and received
from interested parties. The Environ-
mental Protection Agency has carefully
considered all comments received. No
changes were made in the guidelines as
carJier proposed. All written comments
are on file with the agency.
Effective date.—These regulations shall
become effective October 10. 1973.
Dated September 4,1973.
JOHN QUARI.ES.
Acting Administrator.
APPENDIX A
COST xrrrcrivENEss ANALYSIS GUIDELINES
A. Purpose.—Theie guidelines provide ft
basic methodology for determining the moat
cost-effective waste treatment management
system or the most con-effective component
port of any waste treatment management
system.
b. Authority—The guidelines contained
herein are provided pursuant to section 212
(2) (C) of the Federal Water Pollution Con-
trol Act Amendments of 1972 (the Act).
c. Applicability—These guidelines apply
to the development of plans for and the
selection of component parts of a waste
treatment management system for which a
Federal grant Is awarded under 40 CFR,
Part 35.
d. Definitions—Definitions xjf terms used
In these guidelines are as follows:
(I) Waste treatment management sys-
tem.—A system used to restore the Integrity
of the Nation's waters. Waste treatment
management system Is used synonymously
with "treatment works" as defined In 40
CFR. Part 35905-15.
(2) Cost-effectiveness analysis.—An analy-
sis performed to determine which waste
treatment management system or compo-
nent part thereof will result In the minimum
total resources costs over time to meet the
Federal, State or local requirements.
(3) Planning period.—The period over
which a waste treatment management sys-
tem Is evaluated for cost-effectiveness The
planning period commences with the Initial
operation of the system.
(4) Service life.—The period of time dur-
ing which a component of a waste treat-
ment management system will be capable of
performing a function.
(6) Useful li/e.—The period of time dur-
ing which a component of a waste treat-
ment management system will be required to
perform a function which is necessary to
the system's ope-ation.
e. Identification, selection and screening
of alternatives—(1) Identification of alter-
natives.—All feasible alternative waste man-
agement systems shall be Initially Identified.
These alternatives should Include systems
discharging to receiving waters, systems
using land or subsurface disposal techniques,
end systems employing the reuse of waste-
water. In Identifying alternatives, the possi-
bility of staged development of 'the system
shall be considered.
(2) Screening of alternatives.—The Iden-
tified alternatives shall be systematically
screened to define those capable of meeting
the applicable Federal, State, and local
criteria.
(3) Selection of alternatives—The
screened alternatives shall be initially ana-
lyzed to determine which systems hove cost-
effective potential and which should be fully
evaluated according to the cost-effectiveness
analysis procedures established in these
guidelines.
(4) Extent o/ effort.—The extent of effort
and the level of sophistication used In the
cost-elfectiveness analysis should reflect the
size and Importance of the project
f. Cost-Effective analysis procedures—(1)
Method o/ Anali/sis.—Ttie resources costs
shall be evaluated through the use of oppor-
tunity costs. For those resources that can be
expressed In monetary terms, the Interest
(discount) rate established In section (f) (5)
will be used. Monetary costs shall be calcu-
lated In terms of present worth values or
equivalent annual values over the planning
period as defined in section (f)(2). Non-
monetary factors (c g , social and environ-
mental) shall be accounted for descriptively
In the analysis In order to determine their
significance and Impact.
fEDERAl REGISTER, VOL 31, NO. 174—MONDAY, SEPTEMBER 10. 1973
- Al -
-------
21&10
The most cost-effective alternative shall be
the wosto treatment management system
determined from the analysln to have the
lowest present worth and/or equivalent an-
nual value without overriding adverse non-
monetary cotts and to realize at least identi-
cal minimum benefits In terms of applicable
Federal, State, and local standards for ef-
fluent quality, water quality, water reuse
and/or land and subsurface disposal.
(3) Planning period —The planning period
for the cost-effectiveness analysis shall be 20
years.
(3) Elements of cost.—The costs to be
considered shall Include the total values of
the resources attributable to the waste treat-
ment management system or to one of Its
component parts. To determine these values,
all monies necessary for capital construction
costs and operation and maintenance costs
shall be Identified.
Capital construction costs used In a cost-
effectiveness analysis shall Include all con-
tractors' costs of construction including over-
head and profit; costs of land, relocation, and
right-of-way and easement acquisition;
design engineering, field exploration, and en-
gineering services during construction; ad-
ministrative and legal services Including
costs of bond sales; startup costs such as op-
erator training; and Interest during con-
struction. Contingency allowances consistent
with the level of complexity and detail of the
cost estimates shall be Included.
Annual costs for operation and mainte-
nance (Including routine replacement of
equipment and equipment parts) shall be
I eluded In the cost-effectiveness analysis.
These costs shall be adequate to ensure ef-
fective and dependable operation during the
planning period for the system. Annual costs
shall be divided between fixed annual costs
end costs which would be dependent on the
annual quantity of v.actcv.-ittr collected ar.cS
treated.
(4) Prices.—The various components of
cost shall be calculated on the basis of mar-
ket prices prevailing at the time of the cost-
effectiveness analysis. Inflation of wages and
prices shall not be considered in the analysis.
The Implied assumption is that all prices
Involved will tend to change over time by
approximately the same percentage. Thus,
the results of the cost effectiveness analysts
Will not be affected by changes In the gen-
eral level of prices.
Exceptions to the foregoing can be made
If their Is Justification for expecting signifi-
cant changes In the relative prices of certain
Items during the planning period. If such
cases are Identified, the expected change In
these prices should be made to reflect their
future relative deviation from the general
price level.
(5) Interest (discount) rate.—A rate of 7
percent per year will be used for the cost-
effectiveness analysis until the promulgation
of the Water Resources Council's "Proposed
Principles and Standards for Planning Water
and Related Land Resources." Alter promul-
gation of the above regulation, the rate
established for water resource projects shall
be used for the cost-effectiveness analysis.
(6) Interest during construction.—I.: cases
where capital expenditures can be expected
to bo fairly uniform during the construction
period. Interest during construction may be
calculated as Ix'/j PXC where:
I=the Interest (discount) rate In Section
P=tho construction period In years.
C^the total capital expenditures.
In cases when expenditures will not bo
uniform, or when the construction period
will be greater than three years. Interest dur-
ing construction shall bo calculated on a
year-by-year basic.
(7) Service life. — The service life of treat-
ment works for a cost-elf ectlveness analysis
shall be as follows:
— -._.__....-_-...,. Permanent
Structures -------------------- 30-60 yearfc
(Includes plant buildings,
concrete process tankage,
basins, etc.; sewage collec-
tion and conveyance pipe-
lines; lift station struc-
tures; tunnels; outfalls)
Process equipment ------------- 1&-30 years
(Includes major process
equipment such as clartncr
mechanism, vacuum filters.
etc.; steel process tankage
and chemical storage facili-
ties; electrical generating
facilities on standby service
only).
Auxiliary equipment ___________ 10-15 years
(Includes Instruments and
control facilities; sewage
pumps and electric motors:
mechanical equipment such
as compressors, aeration sys-
tems, centrifuges, chlort-
nators, etc.; electrical gen-
erating facilities on regular
service).
Other service life periods will be acceptable
when sufficient Justification can be provided.
Where a system or a component Is for
lnte-;m service' and the anticipated useful
life Is less than the service life, the useful
life shall be substituted for the service life of
the facility In the analysis
(8) Salvage value. — Land for treatment
works, Including land used as part of the
treatment process or for ultimate disposal of
residues, shall be assumed to have a salvage
value at the end of the planning period equal
to Its prevailing market value at the time of
the analysts. Right-of-way easements shall
be considered to have a salvage value not
greater than the prevailing market value at
the time of the analysis.
Structures vlll be assumed to have a
salvage value If there is a use for such struc-
tures at the end of the planning period. In.
this case, salvage value shall be estimated
using stralghtline depreciation during the
service life of the treatment works.
For phased additions of process equipment
and auxiliary equipment, salvage value at the
end of the planning period may be estimated
under the same conditions and on the same
basis as described above for structures.
When the anticipated useful life of a facil-
ity Is less than 20 years (for analysis of In-
terim facilities) , salvage value can be claimed
for equipment where It can be clearly dem-
onstrated that a specl&c market or reuse
opportunity will exist.
IFRDoc.73-19104 Filed 9-7-73:8:45 ami
"VU.S GOVERNMENT PRINTING OFFICE: 1975—210-810:80
- A2 -
-------
-------
-------
|