EPA-600/1-78-019
March 1978
Environmental Health Effects Research Series
CONTAMINANTS ASSOCIATED WITH DIRECT AND
INDIRECT REUSE OF MUNICIPAL WASTEWATER
Health Effects Research Laboratory
Office of Research and Development
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL HEALTH EFFECTS RE-
SEARCH series. This series describes projects and studies relating to the toler-
ances of man for unhealthful substances or conditions. This work is generally
assessed from a medical viewpoint, including physiological or psychological
studies. In addition to toxicology and other medical specialities, study areas in-
clude biomedical instrumentation and health research techniques utilizing ani-
mals but always with intended application to human health measures.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/1-78-019
March 1978
CONTAMINANTS ASSOCIATED WITH
DIRECT AND INDIRECT REUSE OF MUNICIPAL WASTEWATER
by
SCS Engineers
Long Beach, California 90807
Contract No. 68-02-2257
Project Officer
Herbert R. Pahren
Field Studies Division
Health Effects Research Laboratory
Cincinnati , Ohio 45268
HEALTH EFFECTS RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U. S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Health Effects
Research Laboratory, U.S. Environmental Protection Agency, and
approved for publication. Approval does not signify that the
contents necessarily reflect the views and policies of the U.S.
Environmental Protection Agency, nor does mention of trade names
or commercial products constitute endorsement or recommendation
for use.
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V
FOREWORD
The U.S. Environmental Protection Agency was created because
of increasing public and government concern about the dangers of
pollution to the health and welfare of the American people.
Noxious air, foul water, and spoiled land are tragic testimony
to the deterioration of our natural environment. The complexity
of that environment and the interplay between its components
require a concentrated and integrated attack on the problem.
Research and development is that necessary first step in
problem solution and it involves defining the problem, measuring
its impact, and searching for solutions. The primary mission of
the Health Effects Research Laboratory in Cincinnati (HERL) is
to provide a sound health effects data base in support of the
regulatory activities of the EPA. To this end, HERL conducts
a research program to identify, characterize, and quantitate
harmful effects of pollutants that may result from exposure to
chemical, physical or biological agents found in the environment.
In addition to valuable health information generated by these
activities, new research techniques and methods are being devel-
oped that contribute to a better understanding of human biochemi-
cal and physiological functions, and how these functions are
altered by low-level insults.
This report presents the state of knowledge concerning
levels, removals, and health effects of contaminants associated
with direct and indirect reuse of municipal wastewater for pot-
able purposes. With a better understanding of the degree of
insult in our drinking water, measures may be developed to over-
come some of these potentially harmful materials.
R. J. Garner
Director
Health Effects Research Laboratory
iii
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PREFACE
eyohen S ""S'iv
natural processes. In modern times" it ha^becJme nc?2as?nqly
necessary to reuse water as populations and product vlty haSe
multiplied and limited water supplies have been used UD How-
ever, this reuse has usually been done on an ^planned basis
It has.been conservatively estimated that, at the Srlsent time
approximately one-third of the population in the uSued Statel'
derives water from sources which are degraded to some extent
by wastewater discharges Excepting the transmission of
infectious diseases, little concern - until very recent!* b**
been given to the disease-producing potential^ s5ch cog-
nation. It is now necessary to review the health effects of
this situation in a more comprehensive fashion.
Since the public health disaster of Minimata, Jaoan in
the late 1950's and early 1960's (caused by ingestion o?'shell-
fish contaminated with methyl mercury) there has been a areat
surge in research concerning environmentally induced health
effects on man. It is now generally accepted that the mvriad
of contaminants which are continuously discharged to the
environment may produce both acute and chronic repercussions
or public health through daily ingestion of air, water and
food. Recently, some forms of cancer, once thought to'be of
genetic etiology, have been projected to be caused or stimu-
lated by environmental contaminants.
One area of critical consideration to public health is
the direct or indirect reuse of municipal wastewater for potable
purposes. Municipal wastewater systems have been the reposi-
tories of virtually every chemical contaminant known to be
produced by man. The very nature of municipal wastewater
streams makes them of critical importance when considering the
environmentally induced health effects on man. Many questions
must be clearly answered before a complete understanding of the
situation will occur: What are the harmful constituents of
municipal wastewater? How well does our present wastewater
treatment technology remove these constituents? What eventu-
ally happens to them in the environment? How well do our
water treatment plants perform in providing Contaminant
removals and a last line of protection? What are the effects
IV
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of the contaminants on the health and well-being of man? This
report is an attempt to assemble and evaluate the existing
literature pertinent to these questions. It is not an in-depth
study. Rather, it is intended to serve as a basis for deter-
mining the health risks involved and the future research require-
ments for direct and indirect potable water reuse.
For purposes of this report, direct reuse is defined as the
discharge of the treated municipal wastewater directly into a
raw water supply without intervening travel, and dilution in
natural surface or groundwater. No such direct reuse currently
exists in the United States; however, direct reuse has been
practiced in South Africa for about ten years, and long-range
plans for direct reuse are being considered in some United
States municipalities (e.g., Denver).
Indirect reuse is defined as the reuse of treated muni-
cipal wastewater as a raw water supply after the wastewater
has entered, comingled, and essentially become a part of a
natural surface or groundwater resource. A significant per-
centage of the nation's raw water supply is derived from surface
waters such as major lakes and rivers, and consists in part of
treated wastewater from other municipalities. This indirect
reuse has long been accepted by the public and the waterworks
industry as normal and inevitable. Indirect reuse also in-
cludes introduction of treated wastewater into groundwater
aquifers through percolation or well injection. This practice
is often labeled groundwater recharge and may be a formal,
intentional program, or simply a result of land disposal of
wastewater.
Obviously, in some cases there is only a fine line
separating direct reuse from indirect reuse. For example, if
a municipal water department owns and operates a large raw
water storage reservoir and treated wastewater is introduced
into that reservoir, even as a relatively small percentage
of the "fresh" water volume, that is considered direct reuse.
Conversely, a large volume of the wastewater in a river in the
Midwest may come from wastewater from upstream municipalities,
and yet a water supply taken from that river would be considered
indirect reuse. Advocates of direct reuse point to comparisons
of this type to show that the stigma attached to well-designed
direct reuse is irrational. Opponents of direct reuse answer
that "two wrongs don't make a right," and that insufficient
knowledge exists about both direct and indirect reuse to ensure
a "safe" water supply for the public.
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ABSTRACT
This report is an attempt to compile the published quanti-
tative data available concerning the health effects associated
with direct and indirect reuse of treated municipal wastewater
for potable purposes. The assembled information includes data
on the effectiveness of conventional water and wastewater treat-
ment and disposal operations in reducing public health contami-
nant concentrations, as well as data on the transport of these
contaminants through the environment back to man. The data have
been organized in such a manner that the various pathways of
pollutants to man can be evaluated for relative public health
significance in order to establish necessary research priorities.
Wastewater treatment processes evaluated include conven-
tional secondary treatment and tertiary processes. Wastewater
disposal techniques evaluated include direct discharge to fresh
surface waters and land application. Water treatment processes
evaluated include conventional treatment (chemical coagulation,
with or without filtration, and disinfection) and advanced water
treatment (carbon adsorption, ion exchange, and reverse osmosis),
A discussion of p.ublic health considerations is also included.
VI
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CONTENTS
Foreword iii
Preface iv
Abstract y1
Figures 1X
Tables x
Section
1 Introduction
6
Objectives
Scope
Approach
2 Wastewater Inputs
3 Primary Treatment
4 Secondary Treatment
Activated sludge
Trickling filter
Aerated lagoons
Ponding
5 Tertiary Treatment
Filtration
Adsorption
Chemical treatment
Ion exchange
Nitrogen removal processes
Disinfection ................... 83
Chlorination
Ozonation
7 Land/Groundwater
8 Fresh Surface Water
vii
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9 Conventional Water Treatment 158
Chemical coagulation and flocculation followed
by solids separation 158
Disinfection 180
10 Advanced Water Treatment 191
Adsorption onto activated carbon
and other materials 191
Ion exchange 209
Reverse osmosis 220
11 Epidemic!ogical and Pathological Evaluation
of Wastewater Contaminants 230
Introduction 230
Water quality parameters 231
Elemental contaminants 234
Biocidal contaminants 243
Synthetic/organic contaminants 252
Biological contaminants 257
REFERENCES 287
vlii
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FIGURES
Number Page
1 Environmental pathways for direct and
indirect potable reuse 4
2 Unplanned wastewater reuse exists for
many groundwater supplies 97
3 Methods of planned recharge 99
4 The effectiveness of a small amount of
N-607 polymer relative to alum for raw
water with a turbidity of 1-250 Jtu 165
ix
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TABLES
Number page
1 Water Quality Parameters 5
2 Elemental Contaminants 6
3 Biocidal Contaminants 6
4 Organic Compound Identification New
Orleans Water Study 7
5 Biological Contaminants 9
6 Literature Review Pertaining To The Composition
of Wastewater Inputs To Municipal Treatment
Systems 11
7 Summary of Water Quality Parameters
Characterizing Wastewater Input to Municipal
Treatment Facilities 15
8 Summary of the Concentration Ranges of
Elemental Contaminants Found in Wastewater
Inputs to Municipal Treatment Systems 17
9 Average Heavy Metal Loadings and Probable
Sources for Twelve New York City Municipal
Treatment Plants 18
10 Summary of the Concentration Ranges of
Biological Contaminants Found in Wastewater
Inputs to Municipal Treatment Systems 19
11 Distribution of Fecal Streptococci in
Domestic Wastewater and Stormwater Runoffs ... 20
12 Literature Reviewed Pertaining to Primary
Wastewater Treatment 22
13 Primary Settling Tank Performance 24
14 Primary Treatment Removal of Metal Elements ... 24
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Number Page
15 Survival of Pathogens During Primary
Treatment 26
16 Literature Reviewed Pertaining to
Activated Sludge 29
17 Activated Sludge Treatment Pollutant
Removals, Los Angeles, CA 32
18 Removals of Trace Metals by Activated
Sludge Processes, Los Angeles, CA 33
19 Percent Removals of Trace Metals by the
Activated Sludge Process 34
20 Possible Carcinogens Included in the Analysis . . 35
21 Removal of Pathogens by the Activated
Sludge Process 36
22 Percent Removals of Biological Pathogens
by the Activated Sludge Process 36
23 Viral Removal by Activated Sludge Treatment ... 37
24 Literature Reviewed Pertaining to
Trickling Filters 40
25 Trickling Filter Process Removal of Trace
Metal Contaminants 42
26 Removal of Pathogens by Trickling Filters .... 43
27 Literature Reviewed Pertaining to
Aerated Lagoons 45
28 Literature Reviewed Pertaining to Ponding .... 47
29 Literature Reviewed Pertaining to Filtration ... 50
30 Results of Ontario, Canada Pilot Plant Study
Involving Filtration Preceded by Chemical
Treatment of Secondary Effluent 52
31 Heavy Metal Removal by Sand Filtration
Following Lime Coagulation 53
32 Removal of Poliovirus I from Ca(OH)2 Flocculated
Effluent by Rapid Sand Filtration as Measured
by Membrane Filter Recovery of Virus 55
xi
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33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
Literature Reviewed Pertaining to Adsorption . . .
Removal of Specific Toxic Materials by
Carbon Adsorption . . .
Literature Reviewed Pertaining to
Chemical Treatment ....
Removals Achieved by Chemical Clarification . . .
Removal of Elemental Contaminants by
Lime Coagulation
Comparison of the Effectiveness of the
Coagulants Tested
Removal of Polio Virus 1 from Secondary
Effluent by Flocculation with Ca(QH)z
Literature Reviewed Pertaining to Ion Exchange . .
Trace Metal Removals by Ion Exchange
Literature Reviewed Pertaining to
Nitrogen Removal
Effluent Nitrogen Concentrations in
Treatment Systems Incorporating
Nitrification-Dentifrication
Literature Reviewed Pertaining to
Chlorination
Identification of Chlorine Containing
Constituents in Chlorinated Effluents
Chlorinated Organics in Wastewater Effluent . . .
Effect of Chlorination on Various Organisms . . .
Literature Reviewed Pertaining to Ozonation . . .
Survival of Polio Virus in Ozonation
Continuous Flow Studies
Nitrogen Transformation in Recharge
Aquifer, MG/1
Nitrogen Transformations Resulting from
Different Spreading Techniques
:,. " a .
57
61
65
68
69
72
"7 O
73
75
77
O 1
81
82
84
86
87
88
92
95
103
104
xii
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Number Page
52 Survival of Pathogens in Soils 113
53 Percentages of the Total Amounts of Iron,
Nickel, Cobalt, Chromium, Copper, and
Manganese Transported by Five Mechanisms
in the Yukon and Amazon Rivers 122
54 Heavy Metal Distribution in Streams 123
55 Metals Coordinated by Ligands Normally
Found in Natural Waters 125
56 Selected Concentrations of Mercury in
Natural Waters 130
57 Mercury Content of Sediments and Plankton/Algae
Samples Collected From Lake Erie 131
58 Biocide Types and Examples 135
59 Persistence of Compounds in River Water 137
60 Estimated Pesticide Half-Lives 136
61 Chlorinated Hydrocarbon Insecticides in
Southern Lake Michigan Sediments 139
62 DDT Concentrations in Stream Sediments 140
63 Dieldrin in River Bottom Silts 138
64 Organic Compounds identified to Date
From Lower Tennessee 143
65 Organic Compound Identifications
New Orleans Area Water Supply Study 144
66 Molecular Constituents Identified in
Natural Water Samples 152
67 PCB Concentrations in Selected Water Courses . . . 153
68 Average Time in Days for 99.9% Reduction of
Original Titer of Indicated Microorganisms
in Waters 155
69 Survival of Enteric Viruses in Water 157
70 Literature Pertaining to Chemical
Coagulation and Clarification 160
xiH
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Number Page
71 A Comparison of the Effectiveness of the
Coagulants Tested on the Raw Surface Water . . . 163
72 Typical Three-Media High-Rate Filtration
Plant Performance 167
73 Percentage of Pesticide Removed by
Conventional Treatment 172
74 Reduction of Human Enteric Viruses in
Water by Chemical Flocculation 178
75 Literature Reviewed Pertaining to
Water Disinfection 181
76 Effect of Ozonation on Chlorinated
Hydrocarbon Insecticides
77 Probable Reaction Products, of Chlorine and
Some Typical Organic Compounds Found in
Polluted Water Supplies
78 Viricidal Efficiency of Free Chlorine in Water . . 187
79 Literature Reviewed Pertaining to Adsorption ... 192
80 Summary of Water Quality Analysis Data From .
Activated Granular Carbon I9o
81 Activated Carbon Filtration at Colorado
Springs Pilot Plant '94
82 Odor Imparted to Odor-Free Water by Pesticides
and Herbicides 197
83 Activated Carbon Required to Reduce Odors
Caused by Pesticides and Herbicides to
Palatable Levels 198
84 Removal of Heavy Metals by Percolation with
Granular Low Volatile Matter Attapulgite Clay. . 199
85 Activated Carbon Removals of Chlorinated
Hydrocarbons Achieved in Laboratory
Experiments 202
86 Removal of Specific Toxic Materials by
Carbon Adsorption 202
xiv
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Number Page
87 Summary of Cumulative Pesticide Removal
at 10-ppb Load 203
88 Removal of Organics by Percolation With
Granular LVM Attapulgite 206
89 Adsorption of Organic Compounds onto
Amberlite XAD-2 Polymeric Adsorbent 207
90 Ion Exchange Resins Selectivity 209
91 Literature Reviewed Pertaining to Ion Exchange . . 211
92 Average Water Quality Characteristics of the
Ion Exchange Pilot Plant Under Typical Operation
Conditions 213
93 Removal of Trace Elemental Contaminants
From Water by Ion Exchange 216
94 Ion Exchange Treatment for Inorganic Mercury . . . 218
95 Literature Reviewed Pertaining to Reverse
Osmosis 222
96 Reverse Osmosis Removal of Elemental
Contaminants 226
97 Metals in the Environment and Their Toxicity . . . 235
98 Biocides in the Environment and Their Toxicity . . 244
99 Summary of Results of Introducing CCE and CAE
from Raw and Finished Water into Mice 254
100 The Minimal Carcinogenic Dose for Three of
the Most Potent Carcinogenic Hydrocarbons
in Susceptible Experimental Animals 255
101 Waterborne Disease Outbreaks 257
102 Waterborne Disease Outbreaks, by Etiology
and Type of Water System, 1975 258
103 Clinical Response of Adult Humans to Varying
Challenge Doses of Enteric Pathogens 261
xv
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Number
104 Average Values for C. Albicans, Coliform
and Fecal Coliform Counts and TOC (Total
Organic Carbon) Determinations in the
Estuarine Water Samples, Long Island,
New York 266
105 U.S. Mortality from Selected Causes Related
to Water Pollution 267
106 Relation of Dosage of S_._ Typhosa to Disease . . . 268
107 Dose of Various Species and Strains of
Salmonella that Caused Disease in
Human Volunteers 269
108 Mean Indicator Densities at the Coney Island
and Rockaways Beaches, New York, During 1973
and 1974 Trials 272
109 Symptom Rates in Percent at Coney Island
and Rockaways Beaches, New York, During
1973 and 1974 Trials 273
110 The Human Enteric Viruses and the Diseases
Associated With Them 276
111 The Human Enteric Viruses that Can be
Waterborne and Known Diseases Associated
with These Viruses 277
112 Published Reports of Poliomyelitis Attributed
to Contaminated Drinking Water 283
113 Minimal Infective Doses of Attenuated Polio
Viruses for Human Hosts by Oral Routes 285
xvi
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SECTION 1
INTRODUCTION
OBJECTIVES
The purpose of this report is to clearly describe the state-
of-the-art knowledge pertinent to potential health effects from
direct and indirect reuse of treated municipal wastewater for
potable purposes. No new basic research is intended. Rather,
the report ties together the results of past and ongoing research:
t The ranges of concentrations of contaminants contained
in the influent to municipal wastewater treatment plants;
0 The effectiveness of conventional wastewater treatment
processes in the removal, modification, or inactivation
of these contaminants;
The potential hazards associated with effluent disposal
practices in regard to the introduction of contaminants
to the ecosystem;
Pathways by which contaminants associated with wastewater
treatment/disposal operations can intersect with man;
The effectiveness of conventional water treatment
processes in the removal, modification, or inactivation
of these contaminants;
The chronic and acute effects of the contaminants within
the human body.
SCOPE
This report compiles the published quantitative data
available concerning the potential health effects associated
with direct and indirect reuse of treated municipal wastewater
for potable purposes. The assembled information includes data
on the effectiveness of conventional water and wastewater treat-
ment and disposal operations in reducing public health contami-
nant concentrations, as well as data on the transport of these
contaminants through the environment back to man. The data
have been organized in such a manner that the various pathways
of pollutants to man can be evaluated for relative public
1
-------
health significance in order to establish necessary research
priorities.
Wastewater treatment processes evaluated include conven-
tional secondary treatment and tertiary processes. Wastewater
disposal techniques evaluated include direct discharge to fresh
surface waters and land application. Water treatment processes
evaluated include conventional treatment (chemical coagulation,
with or without filtration, and disinfection) and advanced
water treatment (carbon adsorption, ion exchange, and reverse
osmosis).
APPROACH
This project was accomplished in three distinct phases
or tasks:
Task I - Literature Review
The first task reviewed the present literature, providing
information and data relevant to the health effects associated
with the direct and indirect reuse of municipal wastewater for
potable purposes. The relevant literature included the
transport and losses of the various contaminants through the
various pathways and unit operations between the raw waste and
usable drinking water.
Library Research--
Research assistants obtained copies of Pe^1nfn* !l*erj~
ture from several major university libraries, the Library of
Congress, information retrieval systems (e.g., NJJJ), and the
SCS Engineers in-house library. Due to the breadth of the
topic, several constraints were placed upon the literature
search in order to assure a workable, yet comprehensive, volume
of information. Major constraints follow:
Only literature published within the last ten years
was reviewed, except in unusual circumstances.
Except in unusual circumstances, only literature
directly addressing wastewater and water treatment
and disposal, and health effects was reviewed.
There is, of course, a large volume of related
literature (e.g., biological, medical, meteoro-
logical) that could provide additional insights;
however, this peripheral literature was excluded
from the investigation.
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Correspondence--
To obtain the very latest scientific information available,
as well as to find areas in which research is presently being
conducted, letters were sent soliciting literature and data
from thefollowing information sources:
State regulatory and public health agencies;
Major sanitary districts known to be conducting
research; and
Universities conducting related research.
The responses from these sources have been incorporated into
the project.
Task II - Data Analysis
The data and information obtained in Task I were organized
and analyzed to trace the movements and losses of the various
contaminants through the pathways associated with direct and
indirect reuse of municipal wastewater. These pathways included
the waste treatment system, any applicable environmental path-
ways such as river transport or groundwater, and the potable
water treatment plant. The potential health significance of
this transport of the contaminants was delineated where infor-
mation was available.
Task III - Report Preparation
This report is organized by pathway, rather than by
contaminant, so that various public health impairing contami-
nants can be traced through wastewater treatment plants,
through the biosphere, and finally back to man. Figure 1
illustrates the alternate pathways that various contaminants
may follow to reach man after leaving the wastewater treatment
plant. In dark relief are those pathways associated with direct
and indirect reuse for potable purposes.
Each major wastewater and water treatment step and disposal
method is treated in a separate subsection of the report. The
report does not, however, contain a separate section for each
contaminant. If the reader is interested in mercury, for
example, he must skip through the report and read about the
fate of mercury during individual treatment processes, when
released to the biosphere, and the consequent health effects on
man. To facilitate the task of tracing a single contaminant
through the report, each section is divided into subsections
by contaminant type.
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FIGURE I. ENVIRONMENTAL PATHWAYS FOR DIRECT
AND INDIRECT POTABLE REUSE.
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The selection of wastewater contaminants for consideration
in this study was difficult, because of the many public health
impairing constituents found in wastewater. Several of the
traditional wastewater parameters (BOD, suspended solids, etc.)
pose no direct threat to public health, although some of the
direct health-impairing contaminants may be associated with
these traditional wastewater parameters. Therefore, some of
the traditional parameters are included.
Within each section of this report (which traces waste-
water contaminants through municipal wastewater treatments,
through the environment, and through water treatment plants,
and which details the epidemiological and pathological effects
on man) information is organized and presented in the following
contaminant groups:
1. Water Quality Parameters
2. Elemental Contaminants
3. Biocidal Contaminants
4. Synthetic/Organic Contaminants
5. Biological Contaminants
The water quality parameters group contains those water
measurements that are traditionally associated with wastewater
treatment systems, as well as those contaminants that do not
readily fit in any other category. Table 1 lists these water
quality parameters. Most of the parameters listed in this
table do not pose a direct threat to public health, but may be
related to public health impairing contaminants. For example,
heavy metals or viruses may be adsorbed to the surface of
suspended solids and may be transported through the wastewater
treatment plant and biosphere in this manner. However, the
nitrogenous compounds (ammonia, nitrates, and nitrites) may
directly threaten public health.
TABLE 1 . WATER QUALITY PARAMETERS
1. Ammonia
2. Biochemical Oxygen Demand (BOD)
3. Chemical Oxygen Demand (COD)
4. Nitrates
5. Nitrites
6. Phosphates
7. Suspended Solids
8. Total Dissolved Solids (TDS)
9. Total Organic Carbon (TOC)
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The elemental contaminants group, consists of the ions,
compounds, and complexes of the metals and metalloids listed in
Table 2. Many of these contaminants are required in trace quan-
tities for normal human metabolic functions, yet higher levels of
these trace elements may cause significant health problems.
TABLE 2 . ELEMENTAL CONTAMINANTS
1 . Aluminum
2. Antimony
3. Arsenic
4. Barium
5. Beryl 1 ium
6. Boron
7. Cadmium
8. Chromium
9.
10.
11 .
12.
13.
14.
15.
16.
Cobalt
Copper
Germanium
Iron
Lead
Manganese
Mercury
Molybdenum
17.
18.
19.
20.
21.
22.
Nickel
Sel enium
Thorium
Tin
Uranium
Zinc
Biocidal contaminants are those contaminants normally
used to control insect or disease vectors. Table 3 lists tnese
biocidal contaminants. DDT, ODD, DDE, aldrin, dieldrin, and
endrin are all chlorinated hydrocarbons; they were considered
separate from the chlorinated hydrocarbon classlfication
because the literature often dealt with these specific pesti-
cides as individual entities.
1.
2.
3.
4.
5.
6.
DDT
DDD
DDE
Aldrin
Dieldrin
Endrin
BIOCIDAL CONTAMINANTS
7. Chlorinated hydrocarbons
8. Arsenated hydrocarbons
9. Organonitrogen pesticides
10. Organophosphorus pesticides
11. Herbicides
12. Soil sterilants
The synthetic/organic contaminants group includes many
synthetically produced organic chemicals that have found their
way into water systems. For the purposes of this report,
information was gathered on any synthetic/organic chemicals in
wastewater treatment processes or the biosphere. A selection
of such contaminants, recently identified by the Environmental
Protection Agency in an evaluation of organic comoounds in the
New Orleans area water supply are listed in Table 4,
Traditionally, biological contaminants have received the
most attention in wastewater treatment, since these contami-
nants may directly cause infection in the consumer. Biological
contaminants considered in this study are listed in Table 5.
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Table 4. ORGANIC COMPOUND IDENTIFICATION
NEW ORLEANS AREA WATER SUPPLY STUDY ( 61 5 )
1 . Acetaldehyde
2. Acetone
3. Alkylbenzene-C2 isomer
4. Alkylbenzene-C2 isomer
5. Alky1benzene-C2 isomer
6. Alkylbenzene-Cg isomer
7. Alkylbenzene-Cj isomer
8. Alkylbenzene-Cj isomer
9. Atrazine
(2-chloro-4-ethylamino-
6-isopropylamino-s^-
triazine)
10. Deethylatrazine
(2-chloro-4-amino-
6-i sop ropy 1 ami no- s_-
triazine)
11. Benzyl butyl phthalate
12. Bromodichloroethane
13. Bromoform
14. Butanone
15. Carbon disulfide
16. Carbon tetrachloride
17. bis-2-Chloroethyl ether
18. Chloroform
19. bis-2-Chloroisopropyl
ether
20. n-Decane
21. Decane-branched isomer
22. Dibromodichloroethane
i somer
23. Dibromochloromethane
24. Dibutyl phthalate
25. 2,6-Di-t-butyl-p_-
benzoquinone
26. Dichlorobenzene isomer
27. 1 ,2-Dichloroethane
28. Dichloromethane
29. Dieldrin
30. Diethyl phthalate
31. Di(2-ethylhexyl)
phthalate
32. Dihexyl phthalate
33. Dihydrocarvone
34. Diisobutyl phthalate
35. Dimethyl phthalate
36. Dioctyl adipate
37. Dipropyl phthalate
38. n-Dodecane
39. Endrin
40. Ethanol
41. p_-Ethyl toluene
42. p_-Ethyl toluene
-------
TABLE 4 (continued)
43. 1,2,3, 4, 5, 7, 7-
Heptachloronorbornene
44. Heptachloronorbornene
isomer
45. Hexachloro-1,3-butadiene
46. Hexachloroethane
47. Isophorone
48. Limonene
49. Methanol
50. Methylbenzoate
51. 3-Methylbutanal
52. 2-Methylpropanal
53. n-Nonane
54. n-Pentadecane
55. Tetrachloroethane isomer
56. Tetrachloroethylene
57. n-Tetradecane
58. Toluene
1 ,1,2-Trichloroethane
1,1,2-Trichloroethylene
n-Tri decane
59
60
61
62
63
64
Trimethyl-trioxp-
hexahydrotrlazine Isomer
Triphenyl phosphate
n-Undecane
65. Undecane-branched isomer
-------
TABLE 5. BIOLOGICAL CONTAMINANTS
1. Adenovirus
2 . C1 ostrich'urn botulinum
3. C1ostridium perfringens
4. Coliforms
5. Coxsackie virus (A&B)
6. ECHO virus
7 . Erysipelothi ix rhusiopathie
8. Escherichia coli
9. Fecal streptococci
1 0. Franci sel1 a tularensis
11. Hepatitis virus
12. Leptospira
13. Listeria monocytogenes
14. Mycobacterium
15. Parasitic worms
16. Polio virus
17. Protozoa
18. Salmonella
19. Shigella
20. Staphylococcus aureus
21. Vibrio cholerae
22. Yeasts
-------
SECTION 2
WASTEWATER INPUTS
INTRODUCTION
Untreated wastewater input composition is the first point of
interest in determining the pathways pollutants may JjJ1^"
wastewater management systems back to man in dl ^V^1^:^
reuse situations. In addition to domestic sewage, Tnput sources
may include various industrial wastes, storm water, and ground-
water infiltration, in various combinations. Moreove , P
proportions of an individual system change with t^e Po
concentrations and volumes va.x-\j
Research surveyed regarding input concentrations to munici-
pal treatment facilities is presented in Table 6 . Substantial
literature concerning input compositions is available for water
quality parameters and elemental and biological contaminants.
With few exceptions, however, input concentrations of biocidal
and synthetic-organic contaminants have not been investigated.
It was therefore difficult to determine the effect of subsequent
treatment processes upon such contaminants. Regulations for
industrial discharges of complex mixtures of organic compounds
generally only require reporting of the BOD or COD, suspended
solids, and similar water quality parameters. In many instances,
industrial concerns themselves may not know the detailed compo-
sition of their waste streams.
Since 1972, the development of the National Pollution
Discharge Elimination System (NPDES) permit programming has
changed the typical input composition to municipal sanitary
systems through increased restrictions on inputs from industrial
waste. In particular, these restrictions have reduced the
amount of heavy metal contaminants entering municipal treatment
systems .
Municipal treatment systems that process only domestic
wastes and that have no excessive infiltration show predictable
diurnal and seasonal patterns. However, most urban sanitary
systems and many rural systems also contain industrial wastes.
Composition and flow volumes may vary significantly as a func-
tion of these industrial inputs. Food processing plants can
10
-------
TABLE 6. LITERATURE REVIEWED PERTAINING TO THE COMPOSITION
OF WASTEWATER INPUTS TO MUNICIPAL TREATMENT SYSTEMS
Contaminant
Reference Number
Water Quality Parameters
Ammon ia
BOD
COD
Chlorides
Cyanides
Fluorides
Nitrates
Nitrites
Oil & grease
Phosphates
Suspended solids
Total dissolved
sol ids
Total organic
carbon
Other (general)
Elemental Contaminants
Aluminum
Arsenic
22, 90, 273, 368, 390, 406, 450, 503,
516, 582, 647, 651, 700
19, 69, 171, 251, 273, 302, 345, 368,
390, 450, 503, 526, 569, 647, 651, 653,
700
19, 69, 134, 171, 251, 312, 390, 391,
450, 516, 526, 582, 647, 651, 700
19, 22, 161, 450, 516
390
390
22, 90, 273, 368, 406, 450, 503, 510,
516, 582, 647, 651
90, 273, 368, 390, 406, 450, 503, 516,
582, 647, 651, 700
541
19, 22, 69, 132, 134, 161, 273, 304,
368, 390, 406, 450, 516, 582, 647, 651,
700
22, 134, 171, 312, 368, 516, 526, 582,
647, 651, 653, 700
1, 390, 647
69, 134, 312, 516, 647
7, 312
26, 134, 390, 538
19, 390
11
-------
TABLE 6 (continued)
Contaminant Reference Number
Barium 19, 390
Cadmium 19, 37, 159, 390, 391, 471, 702
Chromium 19, 134, 159, 390, 391, 462, 471, 473,
702
Cobalt 134, 273, 390, 471, 702
Copper 19, 107, 134, 159, 273, 390, 471, 702
Iron 26, 134, 273, 450, 471, 538, 702
Lead 19, 107, 134, 390, 471, 493
Manganese 134, 273, 390, 450, 471, 702
Mercury 19, 392, 471
Molybdenum 390, 702
Nickel 107, 159, 273, 390, 471, 702
Selenium 19, 390, 391
Tin 390
Zinc 19, 26, 107, 134, 159, 390, 702
Synthetic/Organic 317 434^ 702
Contaminants
Biological Contaminants
Coliforms 134> 163> 251» 368» 390« 526>
ECHO virus 56°
Fecal streptococci 163, 236, 390, 560
Mycobacterium 223
Parasitic worms 223
Polio virus 560
Protozoa 223
12
-------
TABLE 6 (continued)
Contaminant Reference Number
Salmonella 223, 339
Shigella 223
Virus 198, 221
-------
contribute seasonally high BOD discharges; large metal platers
and metal finishers may periodically contribute high metal
waste concentrations. Certain situations require particular
attention when evaluating potential adverse effects on human
health, including:
t Large hospital complexes connected to small sanitary
systems;
Situations in which large amounts of waste from metal
platers and metal finishers discharge to the system;
t Tanneries .discharging to the system;
Petrochemical and related complexes;
Biocide manufacturing facilities;
Specialty chemical manufacturing or formulating facil-
ities; and
0 Combined or heavily infiltrated systems that bypass
excess flow without adequate treatment.
WATER QUALITY PARAMETERS
The water quality parameters that characterize wastewater
entering into a sanitary treatment plant have been extensively
studied. Concentration ranges recorded in the reviewed litera-
ture are presented in Table 7 . Atypical situations that lie
outside these ranges are known to occur under special conditions.
Such exceptions can usually be attributed to excessive industrial
inputs, excessive infiltration, or unusual characteristics of
the fresh-water supply to the service area.
Diurnal flow patterns reported by Nomura and Young ( 486 )
show that suspended solids concentrations in raw sewage are
directly related to sewage flow rates. The suspended solids
content of the raw sewage studied ranged from 20 mg/l in the
late night flow (attributed to infiltration) up to a high of
350 mg/l during the peak daily sewage flow rate.
Storm and municipal systems show considerable variation in
flow rate as a function of time; consequently, contaminant con-
centrations vary greatly ( 7, 368, 502 ). Water quality
parameter variations due to storm system input will be a
function of:
Normal concentrations during dry weather flow
t Amount and duration of precipitation
Time since the last rain
Season
14
-------
TABLE 7 . SUMMARY OF WATER QUALITY PARAMETERS
CHARACTERIZING WASTEWATER INPUT TO
MUNICIPAL TREATMENT FACILITIES*
Constituent Range, mg/l
Ammonia nitrogen 8 to 50
Total nitrogen 20 to 85
Organic-nitrogen 5 to 32
Nitrate-nitrogen 0 to 3
Nitrite-nitrogen 0 to 1
Chloride 25 to 203
Oil and grease 1 to 50
Total phosphorus 4 to 50
Phosphate as PO, 5 to 50
Inorganic phosphorus 8 to 13
Organic phosphorus 1 to 5
BOD 30 to 600
COD 100 to 1000
Suspended solids 30 to 350
Total dissolved solids 250 to 1400
*As reported in the literature reviewed.
15
-------
ELEMENTAL CONTAMINANTS
The type and amount of elemental contaminants contained in
any treatment system input will depend primarily upon the type
and amount of industrial wastes entering that system. A great
deal of material is available on industrial discharges to muni-
cipal systems. A summary range of elemental influent character-
istics as reported in the literature is presented in Table 8.
The Interim Drinking Water Standards have been included to provide
a standard of comparison.
The literature reviewed did not provide a comprehensive
survey of the sources of these metallic contaminants, but the
following factors appear to be important:
Input water composition
Input water scaling and corrosion potential
Type and age of domestic water piping systems
Type and amount of industrial discharges
Type of municipal system (combined or separate storm
water).
The relative significance of these factors will again
depend upon the specific site. The results of a study by Davis
and Jacknow (159) of the 12 municipal treatment plants in New
York City (presented in Table 9 ) give some idea of the ratio
of contributions from various sources that might be expected in
a large urban area. This same study contains source breakdowns
for individual plants. Input from the residential sector con-
tained concentrations exceeding the Interim Primary Drinking
Water Standards by a factor of 2.
A knowledge of the physical and chemical forms of elemental
contaminants is necessary in order to adequately evaluate
potential public health effects. In particular, it is necessary
to know whether these elements are present as particulate
materials or soluble species. Data of this type are apparently
unavailable at this time.
BIOLOGICAL CONTAMINANTS
Information available in the literature concerning input
concentrations of biological contaminants generally addresses
primary indicator organisms rather than specific pathogens. A
summary range of biological contaminants reported in this
literature is presented in Table 10.
T6
-------
TABLE 8 . SUMMARY OF THE CONCENTRATION RANGES OF
ELEMENTAL CONTAMINANTS FOUND IN WASTEWATER INPUTS
TO MUNICIPAL TREATMENT SYSTEMS*
Consti tuent
Range (mg/l)
Interim Drinking
Water Standards
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
Cadmium
Chromium
Cobalt
Copper
Germanium
Iron
Lead
Manganese
Mercury
Molybdenum
Nickel
Selenium
Thorium
Tin
Uranium
Zinc
0.3 to 3.0
No data in literature
0 to 0.02
0 to 0.02
No data in literature
0.5 to 3
0.01 to 0.2
0.01 to 0.3
No data in literature
0.01 to 0.5
No data in literature
0.5 to 6.5
0 to 1
0.05 to 0.15
0..0002 to 0.003
No data in literature
0.05 to 0.5
0 to 0.11
No data in literature
No data in literature
No data in literature
0.01 to 2.10
.05
1
.01
.05
.05
.002
.01
*As reported in the literature reviewed.
17
-------
TABLE 9 . AVERAGE HEAVY METAL LOADINGS AND PROBABLE SOURCES FOR
TWELVE NEW YORK CITY MUNICIPAL TREATMENT PLANTS (159 )
00
Metals
Copper
Chromi um
Nickel
Zi nc
Cadmi um
Total
Loading
3,820
2,340
1,870
10,440
341
Electroplati ng
and
Photoengravi ng
611
345
1 ,010
830
65
Percent-
age of
total
15
14
53
7
19
Estimate
of Resi-
dent!' al
Contribu-
tion
(lb/d)
1 ,440
640
640
1 ,680
128
Other Indus-
tries, Urban
Storm water,
Percent-
age of
Total
38
27
34
16
38
and Other
Contribu-
tions
(lb/d)
1 ,770
1,350
220
7,930
148
Percent
age of
total
46
58
12
76
43
-------
TABLE 10 . SUMMARY OF THE CONCENTRATION RANGES OF
BIOLOGICAL CONTAMINANTS FOUND IN WASTEWATER INPUTS
TO MUNICIPAL TREATMENT SYSTEMS*
Contaminant Range/100 mi
Total coliforms 1 x 106 to 4.6 x 107
Fecal coliforms 3.4 x 105 to 4.9 x 107
Fecal streptococci 6.4 x 104 to 4.5 x 106
Virus 5 to 100,000 virus units/£
*As reported in the literature reviewed.
Pound and Crites (526) reported that raw municipal sewage
contains from 106 to 108 total coliforms and from 480 to 1,677
plaque-forming units (pfu)/£ of enteric viruses. The average
enteric virus density in domestic sewage reported by the ASCE
(198) was approximatelv 500 virus units/100 m£. Coliform densi-
ties averaged 4.6 x lO'/lOO ml. Analyses of wastewater reported
by Kampelmacher and Jansen (339) show that salmonella is regu-
larly present.
Viral concentrations in raw wastewater reported by Foster
and Engelbrecht (223) range from 5 to 100,000 viral pfu/£, with
reported seasonal variations of a mean of 4,000 pfu/£ during warm
months and a mean of 200 pfu/£ during cold months. However, no
universal procedure or system is presently available for culti-
vation of all viruses. It is likely, therefore, that many of
the investigations of virus density in wastewater have not
included all viruses present due to the selectivity of techniques
employed.
Fecal streptococci contaminants present in the domestic
wastewater of seven communities were studied by Geldreich and
Kenner (236). Figures obtained from this study are presented in
Table 11.
19
-------
TABLE 11. DISTRIBUTION OF FECAL STREPTOCOCCI
IN DOMESTIC WASTEWATER AND STORMWATER RUNOFFS (236)
ro
o
Densities/100 ml
Water Source
Domestic wastewater
Preston, Ida.
Fargo, N. D.
Moorehead, Minn.
Cincinnati, Ohio
Lawrence, Mass.
Monroe, Mich.
Denver, Colo.
Storm water
Business district
Residential
Rural
Fecal
Col 1 forms
340,000
1,300,000
1,600,000
10,900,000
17,900,000
19,200,000
49,000,000
13.000
6,500
2,700
FecaV
Streptococci
64,000
290,000
330,000
2,470.000
4,500,000
700,000
2,900.000
51,000
150,000
58,000
Ratio
FC/FS
5.3
4.5
4.9
4.4
4.0
27.9
16.9
0.26
0.04
0.05
Occurrence
Total
Strains Entero-
Examlned cocci
39
50
50
428
50
70
70
1,476
1,158
445
79.5
100.0
90.0
71.5
84.0
78.6
85.7
78.5
80.0
87.4
S.bovLd
S.eqiumA
None
None
10.0
2.8
4.0
1.4
11,4
1.6
0.5
0.5
(*)
S^aecott*
Atypical JUqiu.-
S.&ae.caJLu> ia.CA.tni>
None
None
None
1.6
None
4.3
2.9
1.2
1.4
0.2
20.5
None
None
24.1
12.0
15.7
None
18.8
18.1
11.9
-------
SECTION 3
PRIMARY TREATMENT
INTRODUCTION
Primary treatment is intended to physically remove settle-
able solids and most of the discrete suspended and floating
solids from the municipal wastewater stream preparatory to
secondary treatment. In addition, primary treatment removes a
limited portion of the soluble constituents.
In primary treatment, the wastewater influent is divided
into three output pathways: primary effluent, primary sludge
(including grit, screenings, and precipitated matter), and
aerosols. Effluent from primary treatment can be directly
discharged (until 1977), discharged after disinfection (again
until 1977), or treated by a secondary process. Primary sludge
is normally subject to additional processing. At some ocean
coastal sites, however, the sludge is discharged without further
treatment. Aerosols are rarely a problem, due to the absence
of excessive turbulence.
The information reviewed during this study is tabulated in
Table 12. Most research conducted to date concerns the removal
by primary treatment of water quality parameter constituents.
It is only in recent years that researchers have examined the
effect of primary treatment on various public health impairing
contaminants.
WATER QUALITY PARAMETERS
For several decades, extensive work has been reported con-
cerning general contaminant removal efficiencies for primary
treatment. Removal varies widely, depending upon the physical
and chemical characteristics of the wastewater, the proportion
of settleable solids, concentrations of the solids, and deten-
tion time. Mitchell (453) reported general performance efficien-
cies that could be expected for typical primary treatment.
Removals achieved during a three-year study of an operational
primary treatment system are shown in Table 13.
21
-------
TABLE 12. LITERATURE REVIEWED PERTAINING
TO PRIMARY WASTEWATER TREATMENT
Contaminant Reference Number
Water Quality Parameters
Ammonia 453
BOD 206, 318, 453, 654, 665, 707
COD 251, 318, 443, 453, 665
Oil and grease 251, 453
Phosphates 443
Suspended solids 206, 251, 318, 368, 443, 453, 665, 707
Total organic
carbon 251
Other (general) 280, 318
Elemental Contaminants
Arsenic 453
Cadmium 124, 453, 507
Copper 124, 443, 453, 507
Iron 124, 443
Lead 124, 453, 507
Mercury 124, 453
Nickel 124, 453, 507
Selenium 529
Zinc 124, 443, 453, 507
Biological Contaminants
Coliforms 88, 251, 293, 357, 443, 583, 594
22
-------
TABLE 12 (continued)
Contaminant Reference
Coxsackie virus 88
(A & B)
Escherichia coli 293, 443
Fecal streptococci 293
Hepatitis virus 586
Mycobacterium 88, 223
Parasitic worms 88, 217, 223
Polio virus 51, 88
Protozoa 88, 223
Salmonella 88, 217, 223, 293, 586
Shigella 88, 586
Vibrio cholerae 88
Virus 38, 48, 49, 50, 51, 54, 55, 88, 200,
223, 242, 487, 583
Other (general) 88, 586
23
-------
TABLE 13. PRIMARY SETTLING TANK PERFORMANCE (453)
Parameter
COD
BOD5
Suspended Sol i ds
Oil and Grease
Ammonia Nitrogen
Primary
Influent
(mg/£)
539
269
279
72
34
Primary
Effluent
(mg/£)
315
165
103
28
20
Percent
Removal
42
39
64
61
41
When used as a coagulant during primary treatment, lime is
most effective in reducing certain water quality parameter con-
stituents. When lime addition of 350 mg/l was followed by air
flotation, Mennell et al . (443) reported the following removals:
turbidity, 98.5 percent; suspended solids, 95 percent; COD, 60
percent; and total phosphorus, 99 percent. Total nitrogen
removal varied between 10 and 20 percent. Lower lime dosages
provided proportionally lower removal percentages. The practice
of dosing primary clarifiers with chemical coagulants will
probably increase, as municipalities attempt to cost effectively
meet federal and state water quality standards.
ELEMENTAL CONTAMINANTS
Recent interest in elemental contaminants, particularly
trace metals, has prompted investigation into the partitioning
of these contaminants in the wastewater treatment stream.
Primary treatment receives elemental contaminants in a variety
of forms, e.g., soluble, insoluble, and complexed. The con-
centrations of each form vary intrinsically as a complex
function of such factors as influent metal concentration, pH,
and ligand concentration.
Mitchell (453) reported removal efficiencies for primary
settling over a three-year period at the Hyperion treatment
plant, Los Angeles, California,as shown in Table 14.
TABLE 14. PRIMARY TREATMENT REMOVAL OF METAL ELEMENTS (453)
Copper
Zinc
Nickel
Lead
Arsenic
Cadmium
Chromi urn
Primary
Influent(mg/£)
0.39
0.66
0.30
0.30
0.015
0.01
0.55
Primary
Effluent(mg/£)
0.25
0.42
0.24
0.7
0.017
0.02
0.37
Percent
Removal
36
36
20
32
24
-------
No
inc
explanation was offered to account for the anomaly of
reased lead, arsenic, and cadmium concentrations.
Chen and Lockwood (124), also working with the Hyperion treatment
plant, discussed the partitioning of trace metals with particu-
lates as a function of particle size. It was reported that in
primary effluent, more than 70 percent of the total trace metals
content is associated with particulates as opposed to the solu-
ble ionic form. However, only 10 to 20 percent of the Ni, Pb,
andMn was associated with the particulate fraction. Similar
concentrations of metals were found on the larger (44 ym) and
the smaller (0.2 ym) particles. However, particles as large as
44 pm will settle about 200 times as. rapidly as 3-ym particles.
More efficient removals of elemental contaminants could be
expected by the use of either increased wastewater detention
time, or chemical precipitants (e.g., lime) for particle coagu-
lation. Trace metal removals reported (443) at a lime dose of
388 mg/l approached 100 percent for chromium and copper, 97
percent for iron, and 94 percent for zinc. Molybdenum was not
effectively removed by this treatment.
BIOLOGICAL CONTAMINANTS
Primary sedimentation usually removes less than 50 percent
of coliform and pathogenic bacteria from sewage and is rela-
tively ineffective in removing viruses and protozoa. Literature
concerning the removal of water-borne pathogens by primary
treatment processes reports a varying degree of efficiency,
depending in part on the type of pathogen studied. Table 15
highlights the results of Bryan's investigation of pathogen
survival during primary treatment (88).
In their literature review, Foster and Englebrecht (223)
reported isolation of salmonella from six of seven different
primary effluent samples. The raw sludge also contained members
of this genus, with 19 of 20 samples tested as positive for
salmonella organisms. Tubercle bacilli were reduced about 50
percent in the wastewater stream during sedimentation. It was
concluded that bacterial pathogens are ineffectively removed
from wastewater by primary settling; furthermore, the process
produced a sludge that, without further treatment, constitutes
a health hazard.
Amoebic cysts and parasitic worm ova are also ineffectively
removed by primary treatment, due to their low specific densities
and resulting buoyancy. Ascaris ova are an exception: Foster
and Engelbrecht (223) reported 100 percent settlement of these
ova into the sludge within 15 min.
Viruses, because of their size (.02 to .3 ym), are rarely
removed by sedimentation, except for those that are associated
with wastewater solids. The nature of the surface chemistry of
25
-------
TABLE 15. SURVIVAL OF PATHOGENS
DURING PRIMARY TREATMENT ( 88, 223)
Pathogen
% Removal
Salmonella typhi
Salmonella spp.
Streptococcus faecalis
Mycobacterium
Enteroviruses
Polio viruses
Coxsackie viruses
Amoebic cysts
Parasitic worm ova
Ascar is ova
>50
0-15
<50
48-57
no reduction
no reduction
<50
no effective removal
50-98 (223)
no effective removal (88)
100
26
-------
viral units suggests that adsorption depends strongly on the
chemical environment, would be expected to vary according to
changes in input water chemistry, and would possibly be affected
by chemical additions.
The removal of viruses by primary settling has been both
researched and reviewed extensively by Berg ( 47, 49, 51, 54).
Berg described a project (49) in which only one to two-thirds
of the viral particles had settled out in one day, although 75
percent of the suspended solids had settled. In this review,
Berg discussed several additional studies on viral removal by
primary treatment; all failed to mention detention time, and
more importantly, the levels of virus in the incoming sewage
were not related to those in the effluent.
Although primary settling alone will not effectively reduce
the pathogen content of wastewater, dosing primary settling tanks
with chemical coagulants does show some promise in this regard.
Chemical precipitation, when used during primary treatment, is
capable of removing as much as 99.99 percent of the virus sus-
pended in water, effected through the formation of a coagulant-
cation-virus complex. Elevated pH levels attained during lime
treatment also result in substantial reductions in viral numbers
(242). Lime coagulation during primary treatment brings remark-
able reductions of coliform density as well. A 99.9 percent
coliform reduction was measured at a lime dose of 450 mg/£ (443).
27
-------
SECTION 4
SECONDARY TREATMENT: ACTIVATED SLUDGE
INTRODUCTION
The activated sludge process entails the growth of micro-
organisms in a reactor. This effects partial biological
degradation of organic compounds in wastewater to simpler
organic compounds, carbon dioxide, water, microorganisms, and
energy (206). The basic process requires two equipment compo-
nents: aeration tanks and clarifiers. Active biological sludge
is separated from the effluent in a clarifier and recycled to an
aeration tank.
Activated sludge, the most popular wastewater secondary
treatment process, has been extensively studied, as indicated
by Table 16. Most research has focused on water quality
parameters such as BOD, COD, and suspended solids. The data
are usually presented as percent removal, with removal effi-
ciency determined by difference in influent and effluent con-
centrations. Removal of a specific contaminant can be
accomplished by separation into the sludge or by degradation
through biological activity. Aerosol generation from the
aeration tank is also a possible contaminant pathway.
In view of possible health effects, the difference between
separation and degradation can be significant. If the treatment
process merely partitions a particular contaminant into the
sludge or air, it remains available for migration back to man.
In contrast, biological degradation can terminate the contami-
nant pathway or transform the potentially harmful substance into
a nontoxic form. The separation and degradation components of
the removal process are often not distinguished in the activated
sludge literature.
WATER QUALITY PARAMETERS
Past research on activated sludge processes has concen-
trated on water quality parameters, with primary emphasis on
BOD, COD, and suspended solids. Because of the tremendous
volume of literature associated with BOD and suspended solids,
and the absence of direct health effects from these pollutants,
this report placed greater emphasis on literature dealing with
28
-------
TABLE 16. LITERATURE REVIEWED PERTAINING
TO ACTIVATED SLUDGE
Contaminant
Reference Number
Water Quality Parameters
Ammonia
BOD
COD
Chlorides
Cyanides
Fluorides
Nitrates
Nitrites
Oil and grease
Phosphates
Suspended solids
Total dissolved
solids
Total organic
carbon
Other (general)
Elemental Contaminants
Alumi num
3, 7, 24, 27, 61, 103, 150, 184, 185,
190, 203, 233, 310, 314, 389, 453,
530, 620, 630
2, 7, 61, 77, 103, 108, 147, 185, 190,
289, 310, 320, 368, 389, 398, 425,
430, 453, 485, 516, 574, 622, 635, 665,
690
103, 155, 190, 289, 301, 320, 338,
389, 453, 516, 543, 620, 690
62, 403, 446, 506
320, 405, 453, 506
506
7, 24, 27, 61, 67, 185, 190, 195, 231,
233, 630
7, 67, 185, 233, 630, 702
393, 453, 506,702
7, 10, 26, 27, 61 , 62, 103, 150, 185,
190, 195, 215, 233, 269, 301 , 310,
376, 398, 446, 453, 567, 622, 625, 628
2, 7, 61, 77, 103, 123, 185, 289, 320,
336, 368, 453, 516, 665, 702
103, 147, 185, 263, 446
7, 61 , 62, 185, 311 , 543, 620, 702
203, 205, 206, 280, 302, 318, 606, 620
269, 398, 486
29
-------
TABLE 16 (continued)
Contaminant Reference Number
Elemental Contaminants
Arsenic 506
Barium 506
Boron 185, 446, 506
Cadmium 123, 124, 125, 453, 471, 476, 486,
506, 507, 615
Chromium 31, 33, 123, 124, 320, 453, 456, 462,
471 , 506, 615
Cobalt 186, 471
Copper 31, 33, 123, 124, 125, 320, 430, 453,
471, 486, 506, 507, 615
Iron 123, 124, 186, 471, 486, 506, 615
Lead 123, 124, 125, 453, 471, 486, 506,
507, 615
Manganese 123, 124, 215, 47.1, 506, 615
Mercury 123, 124, 245, 471, 476, 486, 506
Molybdenum 615
Nickel 31, 33, 123, 125, 320, 453, 471, 615
Selenium 506
Zinc 31, 33, 123, 124, 453, 486, 506, 507
Other (general) 506, 615
Biocidal Contaminants
Aldrin 186
DDT 690
Synthetic/Organic
Contaminants 41 0 , 666
30
-------
TABLE 16 (continued)
Contaminant Reference Number
Biological Contaminants
Bacteria 38, 88, 347, 528
Cl ostrich'urn
botuli num 311
Clostridium perfringens 311
Coliforms 61, 293, 311, 472, 516
Coxsackie virus 51, 88, 439
(A & B)
Escherichia coli 293
Fecal streptococci 293, 311, 528
Mycobacterium 223, 293, 311
Parasitic worms 88, 223
Polio virus 51, 53, 88, 411, 412, 439
Protozoa 223
Salmonella 88, 104, 223, 293, 311, 357
Shigella 88, 293, 311
Vibrio cholerae 88
Virus 38, 48, 49, 50, 54, 88, 185, 198, 200,
210, 223, 242, 259, 447, 488, 700
Other (general) 88, 280, 318, 690
31
-------
chemical and biological contaminants of more direct public health
concern.
The various activated sludge processes are all able to
remove over 90 percent of the soluble BOD found in wastewater.
Mitchell (453) recorded data on the removals achieved with
activated sludge processes of these and other water quality
contaminants during his study of the Los Angeles Hyperion
Treatment Plant as shown in Table 17.
TABLE 17. ACTIVATED SLUDGE TREATMENT POLLUTANT
REMOVALS, LOS ANGELES, CA (453)
COD
BOD5
Suspended Solids
Oil and Grease
Phenol s
Ammonia nitrogen
Phosphorus
Cyanide
Treatment
Influent
(mq/£)
315
165
103
28
0.09
20
10.1
0,30
Treatment
Effluent
(mq/£)
31
9
9
0.5
0.009
9.6
3.3
0.13
Percent
Removal
90
95
91
98
90
52
67
57
A? can be seen from this table, relatively high removals of
most water quality contaminants can be attained in a practical
application over an extended period of time. These removal
efficiencies are supported by other researchers and reviewers,
including Noland and Birkbeck (485 ), Huang et al. (302), Rickert
and Hunter (543 ), Lindstedt and Bennett (389), and Besik (62 ).
ELEMENTAL CONTAMINANTS
Although the activated sludge process efficiently removes
biodegradable organic materials, only limited removal of soluble
elemental contaminants from the wastewater stream can be
achieved. The removal of elemental contaminants is governed by
two basic mechanisms: (1) the precipitation of metal hydroxides;
and (2) the adsorption of elemental contaminants by the activated
sludge floe. In either case, the elemental contaminants removed
will be contained in the sludge.
When suspended solids removals were in the 90 to 95 percent
range, 90 percent of the aluminum, iron, mercury, lead, and zinc
settled readily with the biofloc, according to Nomura and Young
(486). Chromium (VI) and nickel median removals of 77 percent
and 50 percent, respectively, were recorded under the same
32
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conditions. Morgan (462) stated that the removal percentages
for chromium could vary, depending upon the treatment process
used. Chromium exists in sewer systems in Cr (III) and Cr (VI);
concentrations depend upon pH. Cr (III) is readily adsorbed on
particles or precipitated as Cr(OH)3. Chromium entering as
Cr (VI) experiences a strongly reducing environment (little or
no dissolved Oo) in sewers and treatment plants, and is thus
reduced to Cr (HI) and either precipitated or adsorbed. Aera-
tion used in activated sludge or stabilization processes can
cause the resolubilization by oxidation of trivalent to hexava-
lent chromium, with resulting effluent water degradation.
The association of trace metals with suspended solids during
the activated sludge process was investigated by Chen and
Hendricks (123) and Chen and Lockwood (124) at the Hyperion
Their work confirms that many trace metals are
suspended solids, although the concentration of
particles does'not appear to depend significantly
Rather, the removal of trace metals from the
Treatment Plant.
associated with
trace metals on
on particle size
waste stream by activated sludge processes depends to a great
extent upon the adsorptive capability of the activated floes.
Mitchell (453) has recorded elemental removal efficiencies
for the Hyperion Plant over a three-year period, as shown in
Table 18.
TABLE 18 . REMOVALS OF TRACE METALS
BY ACTIVATED SLUDGE PROCESSES,
LOS ANGELES, CA (453)
El ement
Copper
Zinc
Silver
Nickel
Lead
Arsenic
Cadmium
Chromium
Influent
(mg/£)
0.25
0.42
0.019
0.24
0.07
0.017
0.02
0.37
Effluent
(mgAO
0.08
0.23
0.012
0.15
0.08
0.013
0.013
0.013
Percent
Removal
68
46
37
38
--
24
35
96
These figures can be compared with the removal percentages
assembled by the state of California as shown in Table 19.
Clearly, the activated sludge process can reduce, but will not
eliminate, trace metal concentrations in the municipal waste-
water stream.
33
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TABLE 19. PERCENT REMOVALS OF TRACE METALS BY
THE ACTIVATED SLUDGE PROCESS ( 615)
Average
Element Percent Removal
Cadmium 56
Chromium 36
Copper 59
Iron 48
Lead 48
Manganese 22
Molybdenum 23
Nickel 22
Silver 71
Zinc 60
SYNTHETIC/ORGANIC CONTAMINANTS
Malaney et al. (410) in a study of the removal of possible
carcinogenic organic compounds by activated sludge, concluded
that no significant reduction was accomplished within normal
detention times at the three treatment plants studied.
Table 20 lists the possible carcinogens included in the
analysis.
Recent work by Wachinski et al. (666 ) suggests that herbi-
cide detoxification can be achieved with a pure oxygen-activated
sludge treatment system that was determined to be both economical
and ecologically safe. A proprietary strain of mutant micro-
organisms, PHENOBAC (developed by the Worne Biochemical Corp.),
was utilized that was able to degrade halogenated phenols. Even
with relatively high herbicide concentrations (1380 mg/£),
degradation of as much as 73 percent was accomplished after a
16-day aeration period using optimum proportions of required
nutrients, microflora, and oxygen. According to the authors,
this figure represents a conservative estimate of possible
reductions, since testing was conducted at 18°C, while the
optimum growth temperature for PHENOBAC is close to 30°C.
BIOLOGICAL CONTAMINANTS
Activated sludge followed by secondary sedimentation can
remove over 90 percent of coliform or pathogenic bacteria that
remain after primary sedimentation; other biological pathogens
are removed to varying degrees. Nonetheless, even with 90
percent removal, appreciable amounts of pathogens remain present
in the effluent.
34
-------
TABLE 20 . POSSIBLE CARCINOGENS
INCLUDED IN THE ANALYSIS (410)
2,3 - Butylene oxide
B - Propiolactone
Thiourea
Ethycarbamate
2 - Thiouracil
4 - Ethoxyphenylurea
Benzidine
4,4' - Dihydroxy-a,b-diethylstilbene
2 - Naphthylamine
4,4' - Bis (dimethylamino) benzopheuone
p-Phenylazophenol
p-Phenylazoani1ine
9,10 - Dimethylanthracene
1,2 - Benzanthracene
7 - Methyl-1,2-benzanthracene
9,10 - Dimethyl-1,2-benzathracene
1,2,5,6 - Dibenzanthracene
3/4 - Benzpyrene
1,2,4,5 - Dibenzpyrene
20 - Methylcholanthrene
2 - Nitrofluorene
2 - Fluoreneamino
N-2 - Fluorenylacetamide
7,9 - Dimethylbenz (c) acridine
7,10 - Dimethylbenz (c) acridine
Dibenz (a,h) acridine
Dibenz (a,j) acridine
35
-------
Pathogens can either be removed by adsorption onto the
sludge floes or destroyed by the predatory activity of the
zoogleal component. A review of the literature (280, 318)
reveals discussion of general wastewater removal rates with
little differentiation between removals and the biocidal prop-
erties of activated sludge.
Foster and Engelbrecht (223) provided a review of pathogen
removal by activated sludge processes. Conclusions of this
review are summarized in Table 21.
TABLE 21. REMOVAL OF PATHOGENS BY
THE ACTIVATED SLUDGE PROCESS (223)
Pathogen Percent Removal
Salmonella 96 to 99
Mycobacterium Slight to 87
Amoebic cysts No apparent removal
Helminth ova No apparent removal
Virus 76 to 99
Ova of intestinal parasites are apparently unaffected by
the activated sludge process; in fact, the literature indicates
that activated sludge-mixed liquor provides an excellent hatch-
ing medium for eggs.
A review by Hunter and Kotalik (311) provided additional
pathogen removal data, as summarized in Table 22.
TABLE 22. PERCENT REMOVALS OF BIOLOGICAL PATHOGENS BY
THE ACTIVATED SLUDGE PROCESS (311)
Pathogen Percent Removal
Col if orm
Fecal streptococci
Shigel la
Salmonel la
Pseudomonas aerogjnosa
Clostridium perfringens
Mycobacterium tuberculosis
90
84
90
70
99
90
66
to
to
to
to
to
99
94
99
99
88
A list of the species of protozoans, nematodes, and fungi
that have been found in activated sludge effluent was also
presented by the authors. Species recorded include:
36
-------
Protozoa -
Fungi -
Amoeba sp.
Epistylis p 1 i c i a t i 1 s
Euplotes patella
Loxophyl1 urn helus
Oikornonas sp.
Pelodinium rem'forme
Phyllomitus anylophagus
Trigonomonas compressar
Vorticel1 a campanula
Nematodes -
Dory!aimus
Monhystera
Rhabdias
Alternaria
Aspergi11 us
Aureobasidium
Candida
Cryptococcus
Fusarium
Fusarium aquaeductum
Fusarium oxysporum
Fusarium roseum
Geotrichum
Hansenula
Kloeckera
Mucqr
Pemci 111 urn
Rhodotorula
Saccharomyces
Torul opsi s
Trichoderma
Trichosporon
The removal of viral contaminants by activated sludge has
recently become the topic of considerable research. In general,
viral removal of up to 90 percent has been observed after the
activated sludge process. However, large variations in removal
have been reported, probably because sampling was not temporally
coordinated (242). Destruction by sewage microflora and virus
adsorption to floe during the process are believed to be the
main factors governing viral removal. Table 23 reports typical
viral removals that can be expected from activated sludge
treatment ( 88 ).
TABLE 23. VIRAL REMOVAL BY ACTIVATED SLUDGE TREATMENT (88)
Pathoqen
Percent Removal
Enterqv iruses
Polio viruses
Coxsackie viruses
ECHO viruses
0 to 90 percent
0 to 90 percent
0 to 50 percent
no apparent removal
Malina et al. (411) concluded from their research that
viral inactivation by activated sludge is independent of the
hydraulic detention time. Polio virus adsorption to sludge is
almost immediate; the adsorbed virus particles are inactivated
according to first order kinetics with a half-life in the range
of 4 to 5 hr . Activated sludge utilizes aeration for optimum
dispersion of the flocculant masses which, along with gases
produced during microbial respiration, may entrain bacterial
37
-------
and viral pathogens in aerosols. The aerosols released are in
the 5-ym diameter range, small enough to permit lung penetration
of a substantial proportion of the particles.
38
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SECONDARY TREATMENT: TRICKLING FILTER
INTRODUCTION
Trickling filters have been widely used for secondary bio-
logical treatment of municipal wastewater, and substantial
literature is available on this process, as indicated on Table 24
The trickling filter system generally consists of a tank
open on both top and bottom. The tank is filled with a rock or
plastic filter media having a high surface area to allow attach-
ment of zoogleal slimes and void fraction for movement and dif-
fusion of oxygen. Contaminant removal is accomplished through
adsorption at the surface of the biological slimes covering the
filter media. Following adsorption, the organics are utilized
by the slimes for growth and energy. The trickling filter is
followed by clarification to remove biological solids periodi-
cally flushed from the filter.
Trickling filter influent is usually from a primary treat-
ment system. System outputs include effluent, sludge, and pos-
sible aerosols.
The literature generally refers to percent removal, with
no distinction made between separation and degradation or des-
truction. As in the case of other secondary processes, the
literature primarily addresses the general and biological con-
taminants and is sparse in the areas of elemental, synthetic,
and biocidal contaminants.
WATER QUALITY PARAMETERS
The removal of BOD and suspended solids by trickling
filters is reported to be from 65 to 95 percent, averaging
about 85 percent (318, 615). The efficiency of trickling
filtration decreases as temperatures fall below 20°C. Imhoff
et al . (318) reported that a reduction of temperature from
20° to 10°C results in an efficiency loss of about 40 per-
cent. Nickerson et al . (479) found that chemical addition ahead
of primary clarifiers increases overall BOD and suspended solids
removals in trickling filters. Lager and Smith (368) reported
that no significant removal of total nitrogen or phosphorus
occurred during the conventional trickling filter process. In
39
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TABLE 24. LITERATURE REVIEWED PERTAINING
TO TRICKLING FILTERS
Contaminant Reference Number
Water Quality Parameters
Ammonia 4, 20, 183, 368, 440, 653, 685
BOD 25, 131, 318, 368, 398, 450, 479, 490,
540, 615, 635, 653, 706
Chlorides 450, 685
COD 131, 258, 440, 450, 686
Nitrates 3, 4, 183, 368, 440, 685
Nitrites 183, 440, 685
Phosphates 32, 324, 368, 398, 440, 490, 685
Suspended solids 261, 318, 368, 479, 490, 615, 653, 706
Total organic 25, 131, 311
carbon
Other (general) 205, 206, 280, 318
Elemental Contaminants
Aluminum 398
Boron 685
Cadmium 615
Chromium 31, 540, 615
Copper 31, 540, 615
Germanium 655
Iron 615, 685
Lead 615, 685
Manganese 615, 68&
Molybdenum 615
40
-------
TABLE 24 (continued)
Contaminant Reference Number
Nickel 31, 431, 540, 615
Zinc 31, 540, 615
Synthetic/Organic
Contaminants 131, 311
Biological Contaminants
Bacteria 38, 76, 88, 210, 254
Coliforms 254, 293, 472, 592
Coxsackie virus 88
(A & B)
Escherichia coli 293
Fecal streptococci 592
Mycobacterium 223
Parasitic worms 88, 223, 311
Polio virus 88
Protozoa 223
Salmonella 88, 223, 357, 592
Shigella 88
Vibrio cholerae 88, 357
Virus 38, 49, 50, 51, 54, 88, 198, 224, 259,
592
Other (general) 88, 254, 318
41
-------
low-rate filters, ammonia and nitrogenous organic compounds are
usually oxidized to yield high proportions of nitrates and some
nitrites in the effluent; high-rate trickling filter effluents
are low in nitrates and nitrites due to limited system oxidation.
Barth et al. (32) reported total phosphorus removals of up to
75 percent with direct dosing of aluminate to a trickling filter
ELEMENTAL CONTAMINANTS
Removal of elemental contaminants by trickling filters is
not well documented. A summary of the literature on metal
removals is shown in Table 25
TABLE 25. TRICKLING FILTER PROCESS REMOVAL
OF TRACE METAL CONTAMINANTS (615 )
Average
Element Percent Removal
Cadmium 5
Chromium 19
Copper 47
Iron 46
Lead 36
Manganese 16
Molybdenum 15
Nickel 20
Silver 48
Zinc 56
Trace metal removals by trickling filters are substantially
lower than those achieved with the activated sludge process be-
cause there is less formation and sedimentation of trace metal
complexes.
BIOLOGICAL CONTAMINANTS
Trickling filters do not effectively remove many biological
pathogens. Table 26 illustrates reported removal efficiencies.
Organisms are adsorbed into the zoogleal slime but due to
similar surface charges and morphology, biocidal effects are
variable (318).
42
-------
TABLE 26. REMOVAL OF PATHOGENS BY
TRICKLING FILTERS (223)
Pathogen Group Efficiency
Salmonel 1 a
Mycobacterium
Amoebic Cysts
Helminth Ova
Virus
88
66
11
62
0
to
to
to
to
to
99
99
99
76
84
.9
.9
Literature by Foster and Engelbrecht (223) revealed that trick-
ling filters are capable of reducing paratyphoid organisms by
84 to 99 percent. A review by Hunter and Kotalik (311) showed
99.7 percent removal of Schistosoma mansoni ova. These authors
also concluded that trick!ing filter effluents can contribute a
major portion of the free living nematode population found in
receiving waters.
Improperly operated low-rate trickling filters can provide
an excellent breeding area for insects, especially filter flies
(psychoda) and springtails. Trickling filters cannot be depen-
ded upon to produce significant or consistent viral reductions.
Foster and Engelbrecht (223) reported removals ranging from 0
to 84 percent. Berg (51) speculated that even when viruses are
adsorbed, they may eventually be replaced by other substances
and leach out of the filter slime as a result of an equilibrium
effect.
43
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SECONDARY TREATMENT: AERATED LAGOONS
INTRODUCTION
Aerated lagoons are aerobic or facultative ponds in which
mechanical aeration is used to increase the rate at which oxy-
gen is made available to facilitate biological stabilization.
The aeration also provides mixing for suspension of microbial
floe. The biological process does not include algae, and organic
stabilization depends on the mixed liquor that develops within
the pond. Literature surveyed concerning aerated lagoons is
listed in Table 27.
WATER QUALITY PARAMETERS
BOD removal by aerated lagoons is a function of aeration
period, temperature, and the nature of the wastewater. The
aeration of a typical domestic wastewater for five days at 20°C
provides about 85 percent BOD reduction; lowering the temperature
to 10°C reduces the efficiency to approximately 65 percent (280).
BIOLOGICAL CONTAMINANTS
A discussion of the literature by Parker ( 503 ) revealed
that coliform reductions in the range of 80 to 99 percent can be
achieved with optimum detention time. This is supported by the
experiments of Carpenter et al. (105), who reported that coli-
form organisms are efficiently removed by the use of aerated
lagoons. Klock (357) stated that the coliform survival rate
in lagoons is a function of the oxidation-reduction potential
and temperature.
Berg (49) discussed the removal of viruses by stabilization
ponds, concluding that virus removal can be expected to be
erratic.
44
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TABLE 27. LITERATURE REVIEWED PERTAINING
TO AERATED LAGOONS
Contaminant
Reference Number
Water Quality Parameters
Ammonia
BOD
COD
Ni trates
Nitrites
Phosphates
Suspended solids
Other (general)
Biological Contaminants
Bacteria
Col iforms
Escherichia coli
Fecal streptococci
Salmonel1 a
Virus
233
47, 252, 280, 332, 386, 654
47, 143, 252
233
233
173, 386
252, 368
206, 280, 318
105, 357
105, 293, 357, 503
503
293, 503
293
49, 105, 200
45
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SECONDARY TREATMENT: PONDING
INTRODUCTION
An oxidation or facultative pond is generally a shallow
earthen basin designed to promote a symbiotic existence between
algae and bacteria (368). Algal photosynthesis and surface
reaction maintain aerobic conditions in the photic region, while
anaerobic bacteria flourish in the aphotic zone. Ponds are
normally operated in series and are sometimes used for
"polishing" effluent from conventional secondary processes.
Influent to a ponding system may be raw sanitary waste,
primary effluent, or secondary effluent. Pond effluent can
enter the environment by direct discharge or by seepage to the
groundwater. Literature reviewed concerning ponding is listed
in Table 28; as can be seen from this review, only a limited
amount of research has examined the removal of contaminants by
the ponding process.
WATER QUALITY PARAMETERS
Oxidation pond removal efficiencies for suspended solids
and BOD can vary widely and may even reach negative values
(368). Removal ranges of 60 to 50 percent have been reported
for suspended solids, and of 70 to 10 percent for BODg. This
variation occurs because most influent BOD is converted into
suspended algal mass. This mass exerts a BOD demand and provides
suspended solids that may be carried out in the effluent.
Bacterial decomposition and algal growth are both retarded,
reducing removal efficiency of the ponding process, by reduced
temperatures (280).
SYNTHETIC/ORGANIC CONTAMINANTS
The removal of trisodium nitrilotriacetate (NTA) by ponding
has been investigated by Klein (356). He found that after a
two-month acclimation period, steady-state removal was in excess
of 90 percent, with influent concentrations in the range of
30 mg/£.
46
-------
TABLE 28. LITERATURE REVIEWED PERTAINING TO PONDING
Contaminant Reference Number
Water Quality Parameters
BOD 172, 280, 368
COD 685
hlorides 222
Fluorides 222
Nitrates 122, 172, 195, 230, 663
Phosphates 172, 195, 221, 230, 685, 693
Suspended solids 206, 368
Other (general) 206, 280, 368
Synthetic/Organic
Contaminants 356
Biological Contaminants
Bacteria 413, 592
Coliforms 417, 480, 592
Escherichia col i 418, 500
Fecal streptococci 417, 418, 592
Salmonella 337
Virus 49, 50, 51, 592
47
-------
BIOLOGICAL CONTAMINANTS
Kampelmacher and Jansen (337) found that removal of
salmonella by oxidation ponds was not inferior to removal
achieved by conventional treatment plants. Species of the
coliform group, although reduced by ponding, are not effectively
eliminated according to Parhad and Rao (500). Slanetz et al.
(592), however, reported that if two ponds were operated in a
series at temperatures of 17° to 26°C, the die-off rate of
coliform, fecal coliforms, and fecal streptococci ranged from
95 to 99 percent. During winter when temperatures were in the
1 to IOC range, the die-off rate was 46 times lower. Berg
( 51 ) states that virus removal by ponding is erratic, ranging
from 0 to 96 percent; virus recovery decreased as the effluent
passed through a series of maturation lagoons.
48
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SECTION 5
TERTIARY TREATMENT: FILTRATION
INTRODUCTION
Inability of gravity sedimentation in secondary clarifiers
to remove small particles (and associated public health impair-
ing contaminants) is a limitation of BOD and suspended solids
removal by conventional wastewater treatment. Filtration as a
tertiary process upgrades treatment performance by removing a
portion of the unsettled suspended solids from secondary efflu-
ents. In addition, filtration often precedes other tertiary
processes such as adsorption and ion exchange since the pre-
sence of suspended solids interferes with the operation of
these processes.
Filtration of wastewater to reduce the suspended solids
concentration is accomplished by passage through a bed of gran-
ular particles. Single, dual, or mixed media beds may be used,
composed of anthracite coal, granite, sand, and/or gravel
(280). Suspended solids are removed by a variety of mecha-
nisms: straining, impingement, settling, and adhesion. The
treatment efficiency of the process is influenced by:
The concentration and characteristics of the wastewater
solids (particle-size distribution, surface character-
istics, organic versus inorganic, etc.);
The characteristics of the filter media and filtering
aids used (particle-size distribution, surface charac-
teri sties , etc.);
The design and operation of the filter.
Since wastewater flow rate and solids content are variable, and
processes upstream of filtration may vary in performance, the
efficiency of filtration may also be expected to vary. For
this reason, values presented in the following discussion
should be considered as merely indicative of the range of
achievable removals.
49
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TABLE 29. LITERATURE REVIEWED PERTAINING TO FILTRATION
Contaminant Reference Number
Water Quality Parameters
Ammonia 21, 287, 438, 615, 706
BOD 64, 166, 348, 377, 438, 611, 615, 649,
706
COD 64, 377, 438, 611, 615
Chlorides 62, 438, 506, 611, 638
Cyanides 506
Fluorides 506
Nitrates 202, 438, 611, 638
Oil & grease 506
Phosphates 59, 64, 166, 335, 438, 615, 649
Suspended solids 19, 59, 233, 280, 335, 377, 615, 638, 649,
670, 706
Total dissolved 506
solids
Total organic 62, 64, 615
carbon
Other (general) 203, 280, 318
Elemental Contaminants
Arsenic 506> 576
Barium 506
Boron 506
Cadmium 18, 19, 391, 506, 507, 714
Chromium 18, 19, 391, 506, 714
Copper 18, 19, 348, 506, 507, 611, 714
Iron 18, 506, 611, 714
50
-------
TABLE 29 (continued)
Contaminant Reference Number
Lead 506, 507, 714
Manganese 18, 325, 506, 611, 714
Mercury 506
Nickel 18, 506, 507
Selenium 18, 391, 506
Zinc 18, 348, 506, 507, 611, 714
Other 18, 506
Synthetic/Organic 5nfi fiqi
/» . iJ\J\j+\Jj\
Contaminants
Biological Contaminants
Bacteria 88, 176
Coliforms 55, 243, 305, 313
Coxsackie virus 49, 88
(A & B)
ECHO virus 560
Hepatitis virus 243
Parasitic worms 88, 678
Polio virus 56, 81, 88, 118, 547, 560, 601
Salmonella 88
Shigella 88
Vibrio cholerae 88, 219
Virus 14, 49, 50, 80, 82, 88, 139, 176, 233,
242, 259, 305, 487, 574, 608
Other 81, 88
51
-------
WATER QUALITY PARAMETERS
In general, the best effluent quality achievable by plain
filtration of secondary effluent is about 5 to 10 mg/l for sus-
pended solids and BOD. The suspended solids content of
secondary effluent was reduced to 5 mg with both rapid sand and
mixed media filters, employed respectively at a treatment and a
pilot plant. Complete removal, however, could not be effected
If further reduction is desired, chemical coagulation must
precede filtration (233, 280).
Two studies (615) indicated that essentially
complete suspended solids removal was accomplished at both a
pilot facility and a major treatment plant when filtration was
preceded by chemical treatment of secondary effluent. Filter
effluent contained 3 mg/l BOD and 25 mg/t COD. Chemical clari-
fier effluent contained 0.7 mg/l total phosphorus; after fil-
tration, this phosphorus content was reduced to 0.1 mg/£ . At
the pilot facility, the filter effluent contained 17.6 mg/l
COD, 9 mg/£ total organic carbon (TOC), and no detectable phos-
phorus, compared with filter influent concentrations of 18.1
mg/l COD, 8.6 mg/l TOC, and 0.4 mg/l phosphorus.
When chemically treated secondary effluent was applied to
rapid-sand filters, generally 20 to 60 percent of applied BOD
was removed, 30 to 70 percent of phosphate, and 40 to 80 per-
cent of the suspended solids (649 ). These values were ob-
tained using a variety of influent concentrations and chemical
dosages. The results of 30 days continuous operation of a
pilot plant practicing filtration preceded by chemical treat-
ment of secondary effluent are summarized in Table 30 (615).
TABLE 30. RESULTS OF ONTARIO, CANADA PILOT PLANT
STUDY INVOLVING FILTRATION PRECEDED BY
CHEMICAL TREATMENT OF SECONDARY EFFLUENT (615 )
Quality Parameter
KdW
Wastewater
secondary
Effluent
Filter
Effluent
Total Organic Carbon 110-165
(mg/l)
BOD5 (mg/l) 230-400
P04 (as P04) 9-21
Total Nitrogen N 27-51
Ammonia N 17-29
Suspended Solids (mg/l) 148-268
14-28
5-14
1.3-3.5
25-37
21-29
13-37
4.5-7.5
2.0-3.0
0.4-1.0
20-35
18-29
3-12
52
-------
Results of a pilot plant study at Cleveland, Ohio - where
chemical coagulation and settling of raw wastewater was
followed by filtration and granular carbon adsorption - were
reviewed by Gulp and Shuckrow (151). On the basis of the data
provided, removals attributable to chemical treatment and fil-
tration can be calculated to be 66 percent of the applied BOD
and 77 percent of the applied COD. A second pilot plant study
reviewed by the authors involved the same treatment scheme.
Removals at this plant due to combined chemical treatment and
filtration can be inferred to range from 77 to 84 percent.
While studying soil filtration, de Vries (166) applied
primary effluent to a sand filter and obtained BOD and phos-
phate removals of nearly 100 percent. Phosphate removals were
attributed to the natural coatings of Fe00r> and Al/,0^ on sand
grains.
ELEMENTAL CONTAMINANTS
Fe2°3
A1203
After chemical treatment, filtration to remove residual
particulate matter may provide some additional removal of ele-
mental contaminants. Elemental contaminant removals achieved
by filtration depend primarily upon the extent of suspended
solids removals, with which the various trace elements are
associated. Table 31, compiled from the literature by Argo
and Culp (is) gives results for sand filtration of some
municipal and industrial wastes.
TABLE 31. HEAVY METAL REMOVAL BY SAND FILTRATION
FOLLOWING LIME COAGULATION (18)
Metal
Cd
Cr+6
Cr+3
Cu
Fe
Mn
Ni
Se
Concentration
Before Filt.
Trace to
0.00075 mq/i
0.0503
2.7
0.79
-
.
_
0.08
.0103
Concentration
After Treat.
0.00070
0.049
0.63
0.32
.5
0.1
1.2 Organic
0.1
1.1 Organic
0.1
0.5
0.00932
PH
8.1
7.6.
7.6
8.7
9.5
10.8
10.5
10.8
10.5
8.7
9.5
11
% Removal
By Filt.
95
6.6
2.6
77
59.5
9.5
53
-------
TABLE 31 (continued)
Metal
Ag
Zn
Concentration
Before Filt.
0.00164
0.97
Concentration
After Treat.
0.00145
0.23
2.5
pH
11
8
9
.7
.5
% Remova
By Filt.
11.6
76.3
1
Patterson ( 506 ) cites evidence from pilot plant studies that
little or no additional removal of arsenic was afforded by fil-
tration of chemically treated municipal wastewater.
BIOLOGICAL CONTAMINANTS
Several investigations have been reported concerning the
removal of viruses by sand filtration. It has been shown that
insignificant virus removal is achieved by rapid filtration
through clean sand (14, 49). However, virus removal efficiency
will be increased by impregnation of the filter medium with
coagulated floe, the presence of organic matter trapped in the
sand, chemical flocculation prior to filtration, or a decrease
in the filtration rate. The addition of iron salts prior to
filtration has resulted in significantly higher coliform reduc-
tions, as discussed by Hunter et al. (313). Similarly,
Robeck et al. ( 547 ) noted that if a low dose of alum was fed to
a rapid coal and sand filter just ahead of filtration, more
than 98 percent of polio virus Type I" could be removed. If the
dosage was increased and conventional f1occulators and settling
were used, removal was increased to over 99 percent. The
authors also noted a general trend toward better removal of
polio virus I with slower filtration rates although their data
were generally erratic. At slow sand filter rates (0.6 to 1.2
-£/min/m2), removal ranged from 50 percent to about 98 percent.
At rapid filtration rates (38 to 76 £/min/m2), virus removals
ranged from about 10 to 70 percent. Similarly, research exam-
ined by Berg (49) showed that filtration through sand at 7.5 If
min/m2 removed 99 percent of the coxsackie virus A5 while fil-
tration at 75 £/min/m2 removed only about 10 percent of the
virus .
Brown et al. ( 81 ) reported 70 to 90 percent removals of
low concentrations of either bacteriophage T2 or polio virus
Type I by filtration through uncoated diatomaceous earth.
However, no significant virus removals by uncoated diatomaceous
earth were achieved in a laboratory study by Amirhor and
Engelbrecht (14). With polyelectrolyte-coated filter media,
removals greater than 99 percent were consistently achieved.
54
-------
In laboratory tests by Berg et al. (56), from 82 to
greater than 99.8 percent of polio virus I was removed from
chemically treated effluent by rapid sand filtration. The
results of these tests are given in Table 32 .
TABLE 32 . REMOVAL OF POLIOVIRUS I FROM.
Ca(OH)2 FLOCCULATED EFFLUENT,BY RAPID
SAND FILTRATION
AS MEASURED BY MEMBRANE FILTER RECOVERY OF VIRUS (56 )
Virus Concentration pfu/l
Test No. Virus Removal
percent
Before Sand After Sand
Filtrationt Filtration
1
2
3
4
5
2,200
15,912
1,940
505
47
397
750
<4.6
12.5
2.8
82;0
95.3
>99.8
97.5
94.0
* Filtration rate 2.25 gpm/sq ft through 8 in of sand.
t Virus concentration in flocculated effluent just prior to
sand filtration.
Laboratory experiments on the removal of nematodes by
rapid sand filtration were conducted by Wei et al. (678 ).
Removal efficiency was about 96 percent when all the nematodes
in the influent were dead or nonmotile. However, most motile
nematodes were able to penetrate the filter bed.
Sand filtration may also provide some removal of amoebic
cysts and ascaris eggs, according to a literature survey by
Bryan (88). He did not indicate the levels of removal affor-
ded.
55
-------
TERTIARY TREATMENT: ADSORPTION
INTRODUCTION
Adsorption refers to the removal from water or wastewater
streams of dissolved contaminants by their attraction to and
accumulation on the surface of an adsorbent substance. Activa-
ted carbon is the most widely used adsorbent in municipal
wastewater treatment to remove trace organics. Adsorption
using activated carbon is utilized as a tertiary treatment
step, usually following sand or multimedia filtration.
Carbon adsorption systems generally utilize granular or
powdered activated carbon packed in a column or forming a fil-
ter bed through which wastewater is passed. Three consecutive
steps occur in the adsorption of wastewater contaminants by
activated carbon: (1) the film diffusion phenomenon, or the
transport of the adsorbate through a surface film surrounding
the activated carbon; (2) the diffusion of the adsorbate within
the pores of the activated carbon; and (3) adsorption on the
interior surfaces of the activated carbon.
Carbon adsorption of contaminants has been the topic of
many research projects as shown in the literature surveyed for
this report, tabulated in Table 33 .
WATER QUALITY PARAMETERS
Adsorption is most effective for removing refractory and
other organics from wastewater. This is especially important
when effluents of exceptional quality are required (e.g., for
groundwater recharge or other reuse applications). Adsorption
can be used either as a polishing step or as the major treat-
ment process (676 ). Rizzo and Schade (544) and Zamtsch and
Morand ( 712 ) reported that carbon columns alone were capable
of about 85 percent removal of BOD from wastewaters entering
the columns. Bishop et al. ( 64, 68) and Zanitsch and Morand
( 712 ) reported 75 to 80 percent TOC removals under the same
conditions. Weber et al. ( 676) found that a treatment system
composed of primary settling, ferric chloride coagulation, and
carbon adsorption could remove up to 97 percent of the influent
BOD.
56
-------
TABLE 33. LITERATURE REVIEWED PERTAINING TO ADSORPTION
Contaminant Reference Number
Water Quality Parameters
Ammonia 61, 64, 65, 103, 438
BOD 61, 64, 65, 84, 92, 103, 151, 167
172, 261, 277, 368, 438, 544, 676,
712
COD 64, 65, 84, 103, 151, 174, 261,
336, 438, 544, 707
Chlorides 62, 438, 494, 598
Nitrates 61, 64, 65, 172, 676
Oil and grease 249
Phosphates 13, 61, 64, 65, 92, 103, 172, 232,
438, 676
Suspended solids 19, 61, 64, 65, 92, 103, 172, 261,
336, 438, 676
Total dissolved
solids 103, 233, 707
Total organic
carbon 61, 62, 64, 65, 68, 167, 277, 518,
544, 587, 676, 712
Other (general) 280, 318
Elemental Contaminants
Aluminum 644
Arsenic 419, 644
Barium 419, 644
Boron 538, 644
Cadmium 18, 19, 315, 370, 372, 419, 549,
644
Chromium 18, 19, 303, 315, 370, 372, 419,
549, 644
57
-------
TABLE 33 (continued)
Contaminant
Reference Number
Elemental Contaminants
Cobalt
Copper
Iron
Lead
Manganese
Mercury
Nickel
Selenium
Zinc
Other (general)
Biocidal Contaminants
Chlorinated
hydrocarbons
Dieldrin
Herbicides
Other (general)
Synthetic/Organic
Contaminants
Biological Contaminants
Bacteria
Col iforms
Escherichia co1i
Polio virus
Virus
370, 644
19, 316, 549, 644
316, 370, 644
370, 419, 644
370, 419, 644
370, 394, 419
370, 419, 644
18, 506, 644
316, 419, 644
18, 372
373, 570
278
370, 272, 570
278, 322, 373, 615
67, 167, 233, 249, 278, 322, 332,
373, 422, 541 , 599, 615, 674, 691
154
61
140
118, 240, 241, 601, 609
133, 140, 242, 259, 488, 608, 609
58
-------
There is some disagreement among researchers regarding the
ability of activated carbon to remove nitrogen species from
wastewaters. Bishop et al. (64) reported that carbon adsorption
had little effect on nitrogen concentrations. On the other hand,
Weber et al. (676) found that their primary settling ferric
chloride coagulation, carbon adsorption system removed 95 per-
cent of the influent nitrate; the reduction was attributed
partly to biological populations growing in the columns.
Weber et al . (676 ) reported that their pilot system also
removed 90 percent of the phosphate in the influent wastewater.
However, much of the research on phosphate adsorption has been
concerned with adsorbents other than carbon. Gangoli and
Thodos (232) reported that both Fl Alumina and fly ash were
capable of removing up to 99 percent of influent phosphate
levels. Ames and Dean (13) demonstrated that an alumina column
could treat up to 400 column volumes before reaching the 10
percent phosphorus breakthrough level.
Since color is contributed largely by organic compounds in
water, high color removal levels with adsorption should be pos-
sible. Zanitsch and Morand (712 ) demonstrated 90 percent
color removal. They also noted an 86 percent suspended solids
removal, presumably by filtration.
ELEMENTAL CONTAMINANTS
Not a great deal of literature is available on the removal
of elemental contaminants by carbon adsorption. Such systems
are not specifically designed to remove ionic elemental con-
taminants, but some elementals are incidentally removed. When
the metallic contaminants are in an organometallic complex,
carbon adsorption columns can remove specific species. Litera-
ture from several sources (315, 372 ) reveals that high removals
(95 percent) of cadmium and hexavalent chromium by carbon ad-
sorption are possible. Huang and Wu (303) found that the effi-
ciency of chromium removal increases with decreasing chromium
concentration. While the mechanism of removal is not well
understood, Roersma et al. (549) were able to describe the
reduction of Cr+6 to Cr+3. The Cr"1"6 is adsorbed within the
pores of the activated carbon which, in turn, is slowly oxi-
dized to COg, reducing the chromium ion.
Activated carbon treatment of a secondary-treated munici-
pal wastewater was found to reduce selenium from 9.32 to 5.85
ppb in a study cited by Patterson ( 506). This represents a 37
percent removal efficiency. Patterson cited a second study in
which the selenium removal efficiencies of several advanced
wastewater treatment processes were determined in t'he treatment
of secondary effluent containing 2.3 ppb selenium. While sand
filtration alone reduced the effluent concentration by 9.5 per-
cent, sand filtration followed by activated carbon treatment
59
-------
provided a cumulative removal of 43.2 percent of the selenium
from the secondary effluent.
Logsden and Symons (394) researched the removal of mercury
by carbon adsorption and found that powdered carbon, in a jar
test, would adsorb both inorganic and methyl forms in excess of
70 percent.
B.IOCIDAL CONTAMINANTS
Carbon adsorption is widely applied to remove organic or
metaV-organic biocides. The removal of insecticides and pesti-
cides has been reviewed by Hager and Flentje (278). Dieldrin,
lindane, parathion, and 2, 4, 5-T ester were reduced below the
detectable limit of 0.01 ppb with influent concentrations of
3.6 to 11.4 ppb. Influent concentrations of 3, 5 dinitro-o-
cresol of 30 to 180 ppb were reduced to less than 1 ppb by
carbon adsorption. It was concluded that granular carbon beds
will provide a margin of safety for treatment of water contain-
ing varying insecticide or pesticide residues.
Activated carbon removals of several pesticides and PCB's
are well illustrated by results of laboratory studies cited by
the California State Water Resources Control Board (615 ), as
shown in Table 34. A variety of pesticides were experimentally
added to distilled water and passed through carbon filters to
test removal efficiencies. Schwarz (570) investigated the ad-
sorption of isoprophyl N-(3-chlorophenyl) carbamate (CIPC) onto
activated carbon, concluding that powdered activated carbon
readily adsorbs CIPC from aqueous solution. The adsorption of
CIPC on activated carbon was independent of the pH in the range
of 5 to 9.
Grover and Smith (272) studied adsorption onto activated
carbon of the acid and dimethylamine forms of 2, 4-D, and
dicarbamate. A strong adsorption effect was noted on both the
acidic and salt forms of the compounds. This effect was expec-
ted to increase at low pH values.
On the basis of the literature which has been reviewed, it
can be concluded that activated carbon adsorption is effective
in the removal of some biocidal contaminants; however, further
investigation of this process will be useful.
SYNTHETIC/ORGANIC CONTAMINANTS
As was mentioned earlier, activated carbon is most erfec-
tive at removing organic contaminants from aqueous solutions.
It is particularly effective at removing organics of low water
solubility, as are many synthetic organic compounds. In general,
carbon adsorption following secondary treatment is capable of
60
-------
TABLE 34. REMOVAL OF SPECIFIC TOXIC MATERIALS
BY CARBON ADSORPTION (615)
Carbon
Dosage (mg/£)
Control
1.0
2.0
2.5
5.0
10.0
12.5
25.0
50.0
AldHn
48
26
«
15
12
6.3
4.4
Endri n
62
--
15
3.4
1.5
0.56
0.22
Residual (ppb)
Oleldrin DDT ODD DDE Toxaphene Arochlor 1242
19 41 56
41
6.3 6.9
21
2.4 3.7 3.7
1.1 ~ 2.2
<1
0.45
0.35
38
34
29
12
3.3
1.1
0.9
155 45
147
80 7.3
31 1.6
2.7 1.1
_.
-
Arochlor 1254
49
37
17
4.2
1.6
1.2
-------
producing an effluent with from 1 to 7 mg/t of organic carbon
(233).
Bishop et al. ( 68 ) found that carbon adsorption was least
effective in removing highly polar, highly soluble organic
species. DeWalle and Chian (167) found that removal was a
function, at least in part, of the molecular weight of the
synthetic organic contaminant: low (<100) and high (>50,000)
molecular weight compounds are poorly adsorbed. The major
fraction removed by adsorption falls into a 100 to 10,000 mole-
cular weight range.
Studies of the adsorption of 93 petrochemicals by Giusti
et al . (249) confirmed the results of Bishop et al. (68) and DeWalle
and Chian (167); adsorption is largely a function of molecular
weight, polarity, solubility, and branching. Ability to function
substantially affected solubility and polarity. The relative
amenabilities to carbon adsorption of straight chain molecules
of fewer than four carbon atoms were as follows: >aldehydes
>esters >ketones >alcohols >glycols. For larger molecules, the
alcohols moved ahead of the esters.
Much of the research done on the adsorption of synthetic
organic compounds from wastewater has been concerned with
determining mechanisms of adsorption and optimum removal con-
ditions. The only general removal efficiency studies available
report removals in terms of total organic carbon with little or
no effort made to differentiate the organic compounds involved.
Based on these results, adsorption can reduce the levels of
synthetic organic compounds in a typical domestic wastewater by
75 to 85 percent. If a particular type or types of organic
compounds predominate in a wastewater, these removals must be
adjusted to reflect the effect of compound character on the
adsorption process.
BIOLOGICAL CONTAMINANTS
With the exception of enteroviruses, no information was
found on the adsorption of biological contaminants, although
incidental removal of other organisms would be expected by
filtering action. Adsorption brings about simple removal of
viruses from wastewater rather than inactivation or destruction
(140, 242). Consequently, viable viruses could be reintroduced
to wastewater should desorption of viruses adsorbed to activa-
ted carbon occur.
Columns of granular activated carbon removed between 18
and 40 percent of Type I polio virus from secondary effluent
in studies by Sproul et al. ( 609). This research and research
by Gerba et al . (241) using Type I polio virus indicate that
adsorption is inversely related to the concentration of organic
matter in the wastewater. * The organics and the virus compete
62
-------
for adsorption sites; consequently, desorption of virus can
occur as adsorption of organic matter continues, or if the
concentration of organics is increased. Several authors have
thus concluded that the process is not dependable for producing
virus-free effluents (133, 242, 609 ).
The level of removal actually attained is closely related
to the type of treatment that precedes adsorption. For example,
reducing the concentration of soluble organics in wastewater
by lime coagulation increased polio-virus removal in studies by
Gerba et al. (240, 241). In addition, the degree of virus ad-
sorption from lime-treated wastewater exceeded that from fil-
tered wastewater. These investigations also showed that polio-
virus removal from wastewater effluents is greatly improved by
maintaining a pH value in the range of 3.5 to 4.5. It was
found that virus adsorbed at low pH could become desorbed by a
rise in pH.
63
-------
TERTIARY TREATMENT: CHEMICAL TREATMENT
INTRODUCTION
The purpose of chemical treatment is to coagulate suspen-
ded solids and cause the precipitation of phosphate and various
trace metals. Chemical coagulation of secondary effluents may
be accomplished by the addition of lime, alum, polymers, or
iron salts, and involves three operations: (1) injection and
rapid mixing of the coagulants to neutralize the predominantly
negative charges on suspended matter; (2) gentle stirring to
promote agglomeration of the coagulated particles into large,
settleable floe; and (3) sedimentation to provide gravity sep-
aration of the flocculated material from the wastewater. The
settled material is disposed to a sludge-handling system. As
indicated by Table 35, a great deal of information is avail-
able concerning the removal of various public health impairing
contaminants by chemical treatment processes.
WATER QUALITY PARAMETERS
Culp and Shuckrow (151) investigated chemical treatment of
raw wastewater with lime and found that removals of 95 to 98
percent phosphorus and 99 percent suspended solids can be
achieved with chemical clarification followed by carbon adsorp-
tion. The treatment of municipal wastewater with alum precipi-
tation as studied by Shuckrow et al. ( 582) resulted in
removal efficiencies of 85 percent for COD and 83 percent for
total organic carbon.
The removal of BOD, suspended solids, and phosphorus as
reviewed by Lager and Smith (368) is summarized in Table 36
Removals from secondary effluents of the magnitudes listed
obviously provide a high quality effluent.
64
-------
TABLE 35. LITERATURE REVIEWED PERTAINING TO CHEMICAL TREATMENT
Contaminant Reference Number
Water Quality Parameters
Ammonia 21, 65, 150, 155, 204, 301, 310, 438,
440, 613, 700
BOD 64, 69, 150, 151, 155, 178, 261, 310,
368, 387, 389, 397, 398, 432, 438,
479, 489, 490, 569, 622, 646, 649,
651 , 676, 700
Chlorides 438
COD 64, 65, 69, 134, 150, 151, 155, 174,
261 , 438, 582
Cyanides 58, 453, 477
Fluorides 215, 613
Nitrates 64, 65, 69, 134, 150, 151, 155, 174,
261, 438
Nitrites 155, 204, 440, 517, 613, 700
Phosphates 6, 10, 32, 59, 64, 65, 69, 150, 151,
155, 156, 160, 172, 173, 195, 215,
218, 248, 269, 301, 310, 331, 354,
367, 368, 376, 387, 389, 398, 426,
431, 438, 440, 489, 490, 495, 497,
567, 569, 590, 607, 613, 622, 625,
649, 651, 675, 693, 700, 707, 710
Suspended solids 18, 59, 64, 65, 134, 151, 175, 261,
301, 349, 368, 389, 397, 443, 479,
489, 490, 569, 582, 623, 649, 651,
686, 700
Total dissolved
solids 150, 569, 613
Total organic
carbon 64, 65, 69, 155, 582, 676
Other (general) 203, 205, 206, 280, 318
65
-------
TABLE 35 (continued)
Contaminant Reference Number
Elemental Contaminants
Aluminum 178, 398, 495, 644
Antimony 18
Arsenic 18, 419, 453, 506, 615, 644
Barium 18, 419, 506, 615, 644
Boron 644
Cadmium 18, 19, 58, 391, 419, 453, 525, 615,
644, 696, 697, 698
Chromium 18, 19, 106, 391, 419, 615, 644, 696,
697, 698
Cobalt 644
Copper 18, 19, 58, 106, 419, 453, 615, 644,
696, 697, 698
Iron 18, 178, 376, 615, 644, 696, 698
Lead 419, 453, 615, 644, 696, 698
Manganese 18, 178, 215, 419, 615, 644, 696,
697, 698
Mercury 18, 379, 394, 419, 453, 513, 615,
631, 644, 696, 697, 698
Molybdenum 18, 615
Nickel 18, 419, 453, 615, 644, 696, 697
Selenium 391, 615, 644
Uranium 18, 615
Zinc 18, 58, 419, 453, 615, 644, 696, 697,
698
Other (general) 18, 372, 389, 615, 698
66
-------
TABLE 35 (continued)
Contaminant Reference Number _^
Synthetic/Organic ,. fiQ,
Contaminants a, o»i
Biological Contaminants
Adeno virus 705
Bacteria 38, 176, 179, 338, 389, 407, 649
Coliforms 55, 155, 243, 389, 443, 649
Coxsackie virus
(A&B) 51, 705
CHO virus 705
Escherichia coli 433, 561, 643
Fecal streptococci 389
Hepatitis 241, 705
Parasitic worms 407
Polio virus 56, 86, 118, 262, 601, 609, 643,
700, 705
Protozoa 407
Salmonella 338
Virus 38, 48, 50, 51, 86, 116, 117, 132,
133, 138, 154, 155, 176, 198, 199,
242, 416, 487, 504, 510, 575, 602,
608, 609, 700, 701
67
-------
TABLE 36. REMOVALS ACHIEVED BY CHEMICAL
CLARIFICATION (368)
Chemical
Lime pH 11.5
Ferric Chloride
170 mg/£ dose
BOD
Removal
(Percent)
80
80
Suspended Solids
Removal
(Percent)
90
95
Ferric Chloride 75
80-100 mg/l dose
Phosphate removal by chemical precipitation (lime) has
received considerable attention in the literature in recent
years. The research on phosphate removal in general indicates
that lime clarification usually provides removal efficiencies
greater than 90 percent. This is supported by the work of
Davis (160), Sturm and Hatch (625 ), Johnson (331), and '
Bernhardt et al. (59 ).
ELEMENTAL CONTAMINANTS
The precipitation of metal hydroxides from solution 1s
governed by the pH and the concentration of the metal ion in
solution. Since many of the trace metals form insoluble hydro-
xides near pH 11, lime coagulation results in a reduction of
these metal concentrations. Table 37 (615 ) summari-
zes the effects af lime coagulation on a number of heavy me-
tals. Some of the data were collected on industrial metal
wastes characterized by metal ion concentrations a great deal
higher than would occur in any municipal plant influent. The
data are included here as examples of possible metal reduc-
tions, since such figures from chemical coagulation of munici-
pal wastewaters are scarce.
As can be seen from these figures, arsenic, molybdenum,
and selenium had relatively poor removal rates,and the poten-
tial removal of mercury was estimated to be low. Only 11 per-
cent of hexavalent chromium was removed, although the trivalent
form was reduced more than 99.9 percent. Most other metals
tested were very effectively reduced at high pH. Lower remo-
vals of these same metals (usually less than 50 percent) can be
achieved with alum coagulation at near neutral pH values
(615 ), a fact that illustrates the dependence of precipitation
on pH .
68
-------
TABLE 37 . REMOVAL OF ELEMENTAL CONTAMINANTS
BY LIME COAGULATION (615 )
Metal
Antimony3
Arsenic3
Barium3
Bi smuth3
Cadmium
Chromium (+6)
Chromium (+3)
Copper
Gold3
I ron
Lead3
Manganese
Mercury3
Molybdenum
Concentration
Before Treatment
mg/£
--
23
--
--
Trace
0.0137
0.56
7,400
15
15,700
7
7
302
15
--
13
17
2.0
15
2.3
2.0
21.0
Trace
11
Concentration
After Treatment
mg/£
--
23
1.3 (sol)b
.0002 (sol)
0.00075
0.050
2.7
0.4
0.79
1
.05
Trace
0.6
<.001 (sol)
2.4
0.1
1.2C
<.001 (sol)b
0.5
Y.ic
0.05
Oxide Soluble
9
Percent
Removal
90
0
Abt. 50
94.5
11
99.9 +
97
99.9 +
86
93
99+
97
90+
82
99 +
40
90+
97
96
45
95
<10
Abt. 10
18
69
-------
TABLE 37 (continued)
Metal
Ni ckel
Seleni um
Si 1 ver
Tel uri uma »"
Ti tanium3 >d
Urani urn6
Zinc
Concentration
Before Treatment
160
5
5
100
16
0.0123
0.0546
--
--
--
17
- -
Concentration
After Treatment
mq/i
0.08
0.5
0.5
1.5
1.4
0.0103
0.0164
(< 0.001?)
(<0 . 001 ? )
7
0.3
.007 (sol)
% Removal
99.9+
90
90
99
91
16.2
97
( 90+)
( 90+)
7
98
90+
The potential removal of these metals was estimated from
solubility data.
Barium and lead reductions and solubilities are based
c upon the carbonate.
These data were from experiments using iron and manganese
. in the organic form.
Titanium and telurium solubility and stability data made
the potential reduction estimate unsure.
Uranium forms complexes with carbonate ion. Quantitative
data were unavailable to allow determination of this effect
70
-------
Pilot plant studies of municipal wastewater containing 5
mg/£ arsenic cited by Patterson (506 ) suggest that chemical
treatment can provide efficient removal of this element.
Ferric sulfate at 45 mg/£ Fe and pH 6.0 removed 90 percent of
the arsenic; lime at 600 mg/£ and pH 11.5 removed 73 percent.
In similar studies cited by Patterson, barium removals of 97
percent were obtained when municipal wastewater dosed with 5
mg/£ barium was treated with 45 mg/l Fe at pH 6.0. Lime at
600 mg/£ and pH 11.5 resulted in 80 percent removal. The re-
moval of cadmium from waters by sorption onto hydrous oxides of
solid metals such as manganese and iron was investigated by
Posselt and Weber ( 525 ). They concluded that sorptive uptake
of cadmium on such materials would constitute a method easily
adaptable to present treatment technology.
BIOLOGICAL CONTAMINANTS
Chemical treatment can be used to reduce or remove many
biological pathogens present in municipal wastewater. Lindstedt
and Bennett (389) evaluated the effectiveness of lime clarifi-
cation in reducing bacterial concentrations, finding that
treatment effectiveness increases with increasing chemical
dosage and pH. At a lime dosage of 400 mg/£ , fecal coliform,
fecal streptococcus, and total coliform concentrations could be
reduced by two orders of magnitude. It was also found that
about 90 percent removal of bacteria can be achieved through
alum clarification over a broad range of alum dosage.
Jar tests employing the f2 bacteriophage virus, lake
water, and a variety of chemical coagulants and polyelectrolyte
coagulant aids were conducted by York and Drewry (705 ). As
shown in Table 38, aluminum sulfate (alum), ferric chloride,
ferric sulfate, ferrous sulfate, and polyelectrolyte B were
found to give maximum virus removals greater than 90 percent at
optimum dosage.
71
-------
TABLE 38 . COMPARISON OF THE EFFECTIVENESS OF
THE COAGULANTS TESTED (705 )
Coagulants-
Coagulant Aids
A12(S04)3
FeCl3
Fe2(S04)3 x H20
FeS04 and Ca(OH)2
Al2(S04h and
Na2OA I2U3
Polyelectrolyte A
Al2(S04)3 and
polyelectrolyte B
Polyelectrolyte B
A12(S04)3 and
polyelectrolyte B
Al2(S04)3 and
polyelectrolyte C
A12(S04)3 and
polyelectrolyte E
A12(S04)3 and
polyelectrolyte F
Al2(S04)3 and
polyelectrolyte D
Dose
25
50
50
36
30
23
2.0
18
1.0
2.0
18
0.7
18
0.4
18
0.1
18
0.1
18
1.0
Maximum
Virus
Removal
percent
99.9
99.4
92.0
93.5
98.6
76
99.2
99.6
99.8
99.3
99.3
99.6
99.4
Berg et al. ( 56 ) experimentally mixed polio virus I and secon-
dary effluent in containers, added lime, and stirred the solu-
tion for 15 min to allow formation of floe particles. Settling
to 75 min. The removals obtained with varying
are shown in Table 39 . Large coagulant doses
were capable of effecting virus removals of up to 99.9 percent.
After further investigation, the authors concluded that signi-
ficant destruction of viruses can be attributed to the high
pH occurring with high lime concentrations (in the range of 400
to 500 mg/£).
followed for 60
dosages of lime
72
-------
TABLE 39 . REMOVAL OF POLIO VIRUS 1 FROM SECONDARY
EFFLUENT BY FLOCCULATION WITH Ca(OH)2 (56 )
Ca(OH)2
Concen-
tration
mg/l
200
300
400
500
500
Initial Virus
Concen-
tration
pfu/£
33,333
51,480
55,000
33,333
33,333
pH of
Treated
Effluent
9.30
10.21
11.30
11.03
11.01
Surviving Virus
Concen-
tration
pfuAe
2,200
15,912
1,940
505
47
Vi rus
Removal
percent
92.3
69.1
96.5
98.5
99.86
Chaudhuri and Engelbrecht (116) used water devoid of
extraneous organic matter in their laboratory investigation of
virus removal with alum. Using the experimentally determined
optimum pH and dosage, 98.0 percent removal of bacteriophage
T4 and 99.9 percent removal of bacteriophage MS2 were obtain-
able. However, the addition of organic matter in the form of
albumin or treated wastewater lowered these efficiencies. For
example, only 95.7 percent removal of bacteriophage T4 was ob-
tained after the addition of 200 ml/I of settled wastewater.
Further experiments demonstrated no inactivation of the virus
particles that were removed in the settled floe. However,
Brunner and Sproul (86 ) demonstrated 60 percent permanent inac-
tivation in the case of polio virus I removed from solution
with aluminum phosphate precipitates. Their studies of polio
virus I and bacteriophage T2 removal showed that under optimum
conditions, removals can reach 98 and 94 percent, respectively,
with aluminum and calcium precipitation. Actual removals are
related to pH and chemical dosage.
Chemical treatment (high pH) holds considerable promise
as a means of effectively inactivating or destroying pathogenic
organisms contained in wastewater. By itself, chemical treat-
ment cannot be relied upon to produce a pathogen-free effluent;
used in conjunction with disinfection, however, it can help
ensure that such an effluent is achieved.
73
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TERTIARY TREATMENT: ION EXCHANGE
INTRODUCTION
The process of selective ion exchange has long been uti-
lized in the treatment of industrial process waters and in domes-
tic water supply softening. Ion exchange resins (539) are
classified by the charge of the exchangeable ion. Thus, resins
may be either catonic or anionic. General purpose resins will
selectively exchange both cations and anions. The operational
features of the ion exchange process are well developed and
reliable. Such systems offer a reliable method of removing
inorganic contaminants from the wastewater stream.
As can be seen by an examination of Table 40 , very little
information is currently available on removals of contaminants
from municipal wastewater by use of ion exchange techniques.
The process has not been economically feasible for treatment of
municipal wastewater. Several research programs focusing on
the application of ion exchange to municipal wastewater treat-
ment are presently under way. The most promising future appli-
cation appears to be for ammonia or nitrate removals.
WATER QUALITY PARAMETERS
Eliassen and Tchobanoglous (194, 195) conducted a review
of the literature. They found that removals of phosphorus and
nitrogen by tertiary wastewater treatment incorporating ion
exchange can reach 90 percent. The actual removal efficiency
was seen to depend upon the type of preceding treatment. Evans
(209) investigated the removal of nitrate by ion exchange, con-
cluding that the strong acid/weak base ion exchange process is
well suited for this purpose. With the exception of these few
studies of phosphorus and nitrate, most research performed to
date has focused on ammonium removal, since specific exchange
resins are not available for either the phosphorus or nitrate
ions. However, some zeolite exchange resins do have unusual
selectivity for the ammonium ion. This fact has encouraged
research activity.
On the basis of both pilot and laboratory scale investiga-
tions, it appears that effluent ammonia concentrations of less
than 1 mg/£ can be expected with ion exchange (362, 438) In
74
-------
TABLE 40. LITERATURE REVIEWED PERTAINING TO ION EXCHANGE
Contaminant
Reference Number
Water Quality Parameters
Ammonia
BOD
COD
Chlorides
Ni trates
Nitri tes
Phosphates
Suspended solids
Total dissolved
sol ids
Total organic
carbon
Other
Elemental Contaminants
Arsenic
Boron
Cadmium
Chromium
Cobalt
Iron
Lead
Manganese
Mercury
3, 65, 90, 103, 150, 194, 233, 362,
438, 445, 517, 539, 694
64, 65, 103, 150, 255, 438
64, 65, 103, 150, 196, 438, 707
196, 438
3, 65, 90, 194, 195, 209, 539, 694
90, 194, 694
64, 65, 103, 150, 194, 195, 196, 197,
209, 238, 438
3, 64, 65, 103
103, 121, 150, 233, 707
64, 65
280, 318
275, 506, 576
538
370, 391 , 506
370, 391 , 506, 542, 549
370
370
370
370
370, 391 , .452, 506
75
-------
TABLE 40 (continued)
Contaminant Reference Number
tlemental Contaminants
Nickel 370
Selenium 391
Other 372, 506
Synthetic/Organic
Contaminants 271 , 541
76
-------
a pilot plant study, Mercer et al. (445) used zeolite columns to
test secondary effluent containing 10-19 mg/l ammonia. Greater
than 99 percent removal of ammonia was achieved. Similarly, 99.7
percent of the ammonia in activated carbon effluent was removed
by a zeolite in laboratory scale experiments by McKendrick et
al. (438).
The Environmental Protection Agency (517) reviewed pilot
plant studies involving the use of clinoptilolite - a naturally
occurring zeolite - for wastewater treatment. Ammonia removals
ranged from 93 to 97 percent.
It should be noted that the ion exchange process using a
zeolite such as cl inoptilol ite does not result in the produc-
tion of a sludge containing the removed ammonia. Rather, the
spent zeolite is regenerated with a lime slurry, which is sub-
sequently air stripped, discharging ammonia to the atmosphere.
ELEMENTAL CONTAMINANTS
Ion exchange techniques have been principally applied for
the removal of elemental contaminants from industrial waste
streams (506 ). Few studies have dealt with the application of
ion exchange techniques to municipal wastewaters for elemental
contaminant removal. Lindstedt et al . (391) investigated trace
metal removal and concluded that a cation-anion exchange se-
quence was effective in reducing the concentrations of cadmium,
chromium, and selenium in secondary effluent. Removal effi-
ciencies are summarized in Table 41.
TABLE 41 . TRACE METAL REMOVALS BY ION EXCHANGE (391)
Percent Removal After Given Process
Cation Cation-Anion
Trace Metal Exchange Exchange
Cadmium
Chromium
Selenium
99
5
1
99.9
96
99.7
BIOCIDAL CONTAMINANTS
Biocidal contaminant removal through ion exchange has also
received little attention in the literature. In the only study
located, Grover (271) stated that trifluralin, triallate,
diallate, and nonionic herbicides were readily adsorbed on
both cationic and anionic exchange resins, with somewhat more
adsorption occurring on the cationic than on the anionic form.
77
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NITROGEN REMOVAL PROCESSES
INTRODUCTION
Interim primary drinking water standards established by the
EPA set a nitrate limit of 10 mg/8, in the nitrogen form. Nitro-
gen concentrations in raw municipal wastewaters generally exceed
this value, ranging from 15 to 50 mg/si. Unless facilities are
specifically designed to remove nitrogen, much of it will remain
essentially unaffected, passing through the varying stages of
treatment to ultimately enter the environment. Moreover, reuse
of wastewater treatment plant effluents for direct groundwater
recharge, indirect groundwater recharge through land application,
or indirect reuse as a potable water supply is on the increase.
Such reuse policies make effective nitrogen removal an important
aspect of any wastewater treatment scheme.
In raw municipal wastewater, nitrogen is primarily found in
the form of both soluble and particulate organic nitrogen and as
ammonium ions. Conventional primary and secondary treatment
transforms some of this organic nitrogen into ammonium ions.
Part of the ammonium ion is oxidized to nitrate, and about 15 to
30 percent of the total nitrogen is removed.
Tertiary treatment processes designed to remove wastewater
constituents other than nitrogen often remove some nitrogen
compounds as well. However, removal is often restricted to
particulate forms, and overall efficiency is generally low. Two
tertiary processes particularly designed to remove nitrogen have
been developed: nitrification-denitrification and ammonia
stripping. Tertiary nitrification-denitrification usually
involves two stages. Nitrification occurs in an initial stage,
during which ammonium ions are oxidized to nitrite and nitrate
ions by nitrifying bacteria. These nitrite and nitrate ions are
in turn reduced to nitrcger. ca: whicn : Imply escapes fro-n ti->e
system.
Ammonia stripping is effective o";y in removing ammonia
nitrogen from municipal wastewater and has no effect on organic
nitrogen, nitrite, or nitrate. Several ammonia strapping plants
are in operation in the U.S. (Lake Tahoe, California, Orange
County, California), but the process has been found to be
expensive. A number of technical problems remain to be solved
as well (438).
78
-------
Nitrification and denitrification are biological reactions
which occur naturally during several conventional treatment
processes such as activated sludge treatments, aerobic lagooning,
and anaerobic digestion. The activated sludge process, in
particular, can be closely controlled to promote nitrogen removal.
Such treatment processes are not principally designed to remove
nitrogen, and both nitrification and denitrification occur only
as secondary reactions. For ease of reference, however, all
literature reviewed on the general topic of nitrogen removal has
been tabulated on Table 42, including tertiary processes
specifically designed for this purpose.
WATER QUALITY PARAMETERS
There is general agreement that a system incorporating
secondary biological treatment and tertiary nitrification-
denitrification should achieve 80 to 95 percent total nitrogen
removal at design flows (280, 483). The nitrification process
alone removes only 5 to 10 percent of the total nitrogen entering
the process, while oxidizing up to 98 percent of the ammonia
nitrogen present to nitrate (236).
Average nitrogen data from systems incorporating nitrifica-
tion-denitrification processes recorded by an EPA Technology
Transfer Publication (236) is presented in Table 43 . Based
on this report, the predicted effluent quality from a nitrogen-
denitrification system will be 1.0 mg/a organic nitrogen, 0.5
mg/x, ammonia nitrogen, 0.5 mg/a nitrate nitrogen, and 2.0 mg/si
total nitrogen.
Nitrification is in itself an oxygen-demanding process and
therefore reduces the total oxygen demand (TOD) in the waste-
water effluent. Conventional biological or physico-chemical
treatment obtaining up to 90 percent BOD reduction will only
partially reduce the TOD of treated wastewater. For instance,
such treatment will only reduce an influent TOD of 490 mg/£ to
an effluent TOD of over 100 mg/a. Nitrification will reduce the
TOD of this effluent to less than 40 mg/a (236).
Since the denitrification step involves the oxidation of
carbonaceous material, a reduction in biochemical oxygen demand
and total organic carbon can also be expected, in addition to
the effective reduction of TOD.
Nitrogen removal by ammonia stripping was studied by
O'Farrell et al. (492), who reported a 90 percent removal of
ammonia from a non-nitrified, lime-clarified secondary effluent
at pH 11.5. During a warm weather study performed at Lake
Tahoe, stripping produced a 95 percent removal of ammonia
nitrogen at pH 11.5 and using 400 cu ft of air per gallon of
wastewater (280). Any arbitrary percentage removal can be
79
-------
achieved with this type of system within available engineering
capabilities, although higher removals mean higher costs.
80
-------
TABLE 42. LITERATURE REVIEWED PERTAINING TO
NITROGEN REMOVAL
Contaminant Reference Number
Water Quality Parameters
Ammonia 3, 4, 6, 40, 66, 127, 194, 204, 236,
280, 328, 428, 438, 475, 483, 492,
517, 527, 539, 594, 620, 630, 684,
694, 706
BOD 40, 236, 330
Chlorides 403
Nitrates 3, 4, 40, 194, 195, 204, 236, 256,
257, 327, 328, 330, 428, 475, 483,
517, 527, 539, 594, 629, 630, 694
Phosphates 194
Suspended
solids 40, 330, 629
81
-------
TABLE 43. EFFLUENT NITROGEN CONCENTRATIONS IN
TREATMENT SYSTEMS INCORPORATING NITRIFICATION - DENITRIFICATION
(236)
Average Effluent Nitrogen, mg/l
Type and Process Sequence Organic-N NHj-N NO^-N NO^-N T°Sal
Lime treatment of raw sewage, 1.1 0.3 0.5 0.0 1.9
nitrification,
denitrification
Primary treatment, 0.8 0.0 0.7 0.0 1.5
high rate activated
sludge, nitrification,
denitrification,
filtration
Primary treatment, 0.8 0.9 0.6 0.0 2.3
roughing filters,
nitrification,
denitrification,
filtration
82
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SECTION 6
DISINFECTION: CHLORINATION
INTRODUCTION
Until recently, chlorination was considered virtually an
unmixed blessing as a cheap, effective method to destroy bac-
teria and viruses. It is now recognized, however, that chlori-
nation of wastewater may create chlorinated compounds harmful
to the environment and to human health. The extent of this
potential hazard has not yet been determined; new and existing
wastewater treatment plants continue to utilize chlorine for
disinfection. The primary purpose of municipal wastewater
chlorination is the destruction of pathogenic microorganisms.
This is reflected in the literature reviewed, shown in Table 44.
WATER QUALITY PARAMETERS
Zaloum and Murphy (711) concluded that chlorination of
treated wastewater effluents does not reduce BOD, COD, and total
organic carbon. Susag (1346), however, found BOD reductions by
chlorination of up to 2 mg/£ per mg/t of chlorine added. These
values are somewhat misleading, in that BOD reduction was due
both to oxidation of the organic material and to the formation
of chlorinated organics resistant to bacterial action.
When chlorine is added to a wastewater containing ammonia
nitrogen, ammonia reacts with the hypochlorous acid formed to
produce chloramines. Further addition of chlorine converts the
chloramines to nitrogen gas. The reaction is influenced by pH,
temperature, contact time, and initial chlorine-to-ammonia
ratio. If sufficient chlorine is added, 95 to 99 percent of
the ammonia will be converted to nitrogen gas with no signifi-
cant formation of nitrous oxide. The quantity of chlorine
required was found to be 10 parts by weight of chlorine to 1
part of ammonia nitrogen when treating raw sewage. This ratio
decreased to 9:1 for secondary effluents, and 8:1 for lime-
clarified and filtered secondary effluent (627 ).
ELEMENTAL CONTAMINANTS
Little information is available on the minimal removal by
chlorination of elemental contaminants. Andelman (16) studied
83
-------
TABLE 44. LITERATURE REVIEWED PERTAINING TO CHLORINATION
Contaminant Reference Number
Water Quality Parameters
Ammonia 21, 36, 62, 65, 71, 360, 361, 517,
531, 597, 713
BOD 65, 171, 298, 499, 516, 569, 627, 711
COD 65, 516, 520, 627, 711
Chlorides 342
Cyanides 28, 499
Nitrates 65, 342, 517, 614
Nitrites 360, 361, 517
Phosphates 65, 342
Suspended solids 65, 516, 569
Total dissolved
solids 569
Total organic
carbon 65, 711
Others (general) 203, 205, 280, 360, 361, 437, 677
Elemental Contaminants
Barium 16
Boron 638
Copper 16
Iron 360, 499
Manganese 360, 361, 559
Mercury 499, 692
Nickel 16, 361
84
-------
TABLE 44 (continued)
Contaminant
Reference Number
Synthetic/Organic
Contaminants
Biological Contaminants
Adeno virus
Bacteria
Coliforms
Coxsacki virus (A&B)
ECHO virus
Escherichia coli
Fecal streptococci
Hepatitis virus
Mycobacterium
Parasitic worms
Polio virus
Protozoa
Salmonella
Shigella
Vibrio cholerae
Virus
Other (general)
5, 42, 85, 102, 250, 334, 464, 536,
581, 596, 619, 669, 713
49
6, 38, 88, 109, 110, 154, 158, 171,
208, 31 1 , 332, 407., 604
88, 89, 158, 171, 195, 201, 208, 251,
307, 311, 360, 361, 454, 516, 604,
608, 647, 649, 673, 687, 689
49, 136, 198, 311 , 439, 564
198, 311 , 585
75, 195, 201, 223, 311, 564, 656, 661
158, 195, 307, 516
311
223, 311
88, 311 , 562, 604
88, 118, 198, 311, 401, 404, 564, 585,
601, 659
88, 201, 223, 621
88, 158, 208, 223, 514
88
88
38, 48, 49, 50, 54, 55, 71 , 88, 109,
110, 152, 153, 185, 200, 201, 208,
233, 259, 311, 332, 365, 368, 400,
401 , 447, 463, 487, 514, 575, 584,
585, 604, 637, 664
88, 296
85
-------
the effects of chlorination on barium, copper, and nickel.
treatment effected a 34-percent reduction in barium, a 5"Perce!?n<;
reduction in nickel, and had no effect upon copper. KokoroDOUic
(360) reported hypochl orous acid reacted with soluble iron ^ n i
and manganese (II) to form precipitates.
SYNTHETIC/ORGANIC CONTAMINANTS
research was found to address removal or Destruction
pouns by . . c«». * .«,. - -...- --:- t'tu-
compounds in water are diverse, including oxidation, substitu-
tion, addition, and free radical reactions. Chlorination may
produce several different chlorinated products from ausing^on
organic pollutant molecule. Some of these compounds have been
identified as toxic to aquatic life by Snoeyink (596 ), Brung*
( 85 ) , and others .
Jolley (334) evaluated chlorine-containing organic consti-
tuents in chlorinated effluents and found that stable chiorm
containing compounds were present after effluents had been d
chlorinated to a 1 to 2 mg/£ chlorine residual. These compound
are identified in Table 45.
TABLE 45. IDENTIFICATION OF CHLORINE CONTAINING
CONSTITUENTS IN CHLORINATED EFFLUENTS (334)
2 - Chlorobenzoic acid
3 - Chlorobenzoic acid
4 - Chlorobenzoic acid
8 - Chlorocaffeine
6 - Chloroguanine
3 - Chloro-4-hydroxybenzoic
4 - Chloromandel ic acid
4 - Chloro-3-methylphenol
acid
2 - Chlorophenol
4 - Chlorophenol
4 - Chlorophenylacetic
3 - Chlororesorcinol
5 - Chlorouracil
5 - Chlorouridine
8 - Chloroxanthine
A similar project was conducted by Glaze and Henderson
(250) The chlorinated organics identified in this study are
listed in Table 46.
Shimizu et al. (581) stated that halogenated nucleic ac1d.
are incorporated into the nucleic acid. Also, the Incorporati
of 5-deoxybromouridine in DNA and 5-fluorouracil into RNA are
known to cause mutations. No work has been completed to deter-
mine how nucleic acids react with chlorine or the resulting
mutations,
86
-------
TABLE 46. CHLORINATED ORGANICS IN
WASTEWATER EFFLUENT (250)
Chloroform
Dichlorobutane 3-chl
Chlorocyclohexane (-18)
0-dichlorobenzene
P-dichlorobenzene
Pentachloroacetone
Trichlorobenzine
Chiorocumene
N-methyl-trichloroaniline
Trichlorophenol
Chloro-a-methyl benzyl alcohol
Dichloromethoxytoluene
Trichloromethylstyrene
Dichloro-a-methyl benzyl alcohol
Dichloro-bis (ethoxy) benzene
Dichloro-a-methyl benzyl alcohol
Trichloro-a-methyl benzyl alcohol
Trichloro-a-methyl benzyl alcohol
Tetrachloroethylstyrene
Tetrachloromethoxytoluene
Dichloroani1ine derivative
Dichloroaniline derivative
Trichlorophthalate derivative
Tetrachlorophthai ate derivative
Dibromochloromethane
3-chloro-2-methylbut-l-ene
Chloroalkyl acetate
Tetrachloroacetone
Chloroethylbenzene
Hexachloroacetone
Dichloroethyl benzene
Dichlorotoluene
Trichloroethyl benzene
Trichloro-N-methylanisole
Tetrachlorophenol
Trichlorocumeme
Tri chlorodimethoxybenzene
Dichloroacetate derivative
87
-------
BIOLOGICAL CONTAMINANTS
The effectiveness of chlorination as a disinfection process
has long been recognized. All researchers are in agreement that
the effectiveness of disinfection by chlorine is influenced by
time and chlorine concentration and also by: (1) whether the
chlorine residual is free or combined; (2) effectiveness of
mixing; (3) whether or not particulates are present; (4) pH;
(5) temperature; and (6) the concentration, condition, and nature
of the organisms. Keeping these limitations in mind, an idea
of the relative resistances of organisms to disinfection by
chlorine can be seen in Table 47.
TABLE 47. EFFECT OF CHLORINATION ON VARIOUS ORGANISMS (311)
Group
Virus
Organism
Infectious Hepatitus
Coxsackie
Coxsackie
Echo
Poliovirus I
Coliphage B
Theiler Phage
Chlorine
Residual
(mg/£)
1
15
5
1.0
1.95
0.53
0.03
0.03
Time
min.
30
30
2.5
3
6.5
14
10
10
Efficiency
Survived
Inactivated
Survived
99.6% Inactivated
Survived
Survived
20% Survival
Inactivated
Bacteria
Nematodes
Others
M. tuberculosis
E . c o 1 i
Coliforms
Total Count
Diplogaster
Cheilobus
S. mansoni
Tova and
miracidia)
S. japonicum
(ova and
mirac i d i a)
1-5
2
1
0.14
0.03
1-1.2
trace
2.5-3
15-45
0.2-0.6
0.2-0.6
120
30
30
3
10
15
15
120
1
30
30
99% Kill
99% Kill
Destroyed
99.9% Kill
52% Kill
99% Kill
98-99% Kill
Survived
Mobile
Killed
Ki 11ed
and
Eliassen and Tchobanoglous (195) found that 2 to 6 mg/£ of
chlorine applied for 20 min would effect a 99.99 percent kill
of the total coliforms, fecal coliforms, and fecal streptococci
present in wastewater influent.
88
-------
The effect of chlorination on entamoebic cysts was investi-
gated by Stringer and Kruse (621 ). It was concluded that the
hypochlorous acid (HOC!) form of free available chlorine was
the most rapidly acting cysticide compared with other halogen
species. Entamoeba histolytica cysts and tapeworm eggs with-
stand the chlorination treatment generally applied to waste
treatment effluent (88). Rudolfs et al. (562) reported the
development of active embryos from a majority of ascaris eggs
in contact with chlorine solutions for 30 min.
Davis and Keen (158) conducted a research project on the
ability of municipal wastewater bacteria to survive chlorination
and reestablish populations after discharge. Fecal coliform,
fecal streptococci, and total coliform enumeration was performed
with further differentiation into lactose nonfermenters within
and outside the family Enterobacteriaceae. It was determined
that the vast majority of the wastewater bacterial species that
reestablished their populations within 21 days following chlori-
nation were lactose nonfermenters not included in the entero-
bacteriaceae. Many of these bacteria could be pathogenic under
the appropriate conditions and may constitute a threat to public
health in receiving waters designated for contact recreation.
Virus inactivation is one of the more difficult tasks of
chlorination, but as in any disinfection process, required kills
can be achieved by lengthening the time or increasing the con-
centration (311). A study of the inactivation of viruses in
wastewaters by chlorination was performed by Lothrup and Sproul
(401). it was ascertained that:
High-level inactivation of viruses can be obtained in
treated and untreated domestic wastewaters. Present
chlorination practices (1 mg/£ of residual), however,
are inadequate for a high level of virus inactivation.
A combined chlorine residual of 28 mg/£ was required
to produce a 99.99 percent inactivation of the T2
bacteriophage in settled raw wastewater after a 30-min
contact time.
t A combined chlorine residual of 40 mg/£ was required to
provide a 99.99 percent destruction of the Type 1
polio virus in settled wastewater after a 30-min contact
time.
Free chlorine residuals of 0.2 to 0.4 mg/l , after 30
min, produced a complete inactivation of the polio virus
and T2 phage in the secondary effluent.
89
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In experimental runs with synthesized storm-water over-
flow samples, a 100 percent inactivation of the Type 1
polio virus was obtained by providing a free chlorine
residual.
The T2 bacteriophage was much less sensitive to combined
chlorine residuals than are the coliform organisms and
somewhat more sensitive than the polio virus to combined
chlorine residuals;
A similar research project investigating the inactivation
of enteroviruses by chlorination was conducted by Shuval et al.
(585). The following conclusions were obtained:
The strain of ECHO virus used was sensitive to the com-
bined chlorine in the sewage, with reductions of 99 per-
cent in 30 min and 99.93 percent in 6 hr using 3.6 mg/l
of chlorine. No virus was recovered in the sample tested
after 4 hr contact with 7 mg/£ of chlorine dosage or
after 2.5 hr with 11 mg/l of applied chlorine. Inacti-
vation was shown to be a function of time and chlorine
concentration under the test conditions.
The strain of polio virus Type 1 used was much less sen-
sitive to the combined chlorine, showing only 50 and 90
percent reductions in 6 hr using 4 and 11 mg/l chlorine
dosage respectively.
Coliform reductions obtained followed known patterns,
with a standard of less than 100 coliforms/100 ml being
obtained in 80 percent of the samples after 2 hr of
contact with a chlorine dose, of about 8 mg/l.
The minimum concentration of chlorine required for complete
inactivation of the Sabin oral poliovaccine Type I virus strain
was examined by Varma et al. (659). Various exposure periods
with pH 5.2 at 20°F were studied. A concentration of 22 mg/£
for 5 min of exposure time, 19 mg/£ for 15 min, 19 mg/l for
30 min, 17 mg/l for 45 min, and 14 mg/l for 60 min. Nonetheless,
on the basis of the literature surveyed, it is evident that
chlorination per se does not provide conclusive proof of disin-
fection.
Boardman and Sproul (71) described the protection afforded
viruses associated in particulate matter. Surface adsorption
gave no viral protection. When viruses are embedded within
particles, the disinfecting molecules must diffuse through the
particle matrix before reaching the virus and initiating any
inactivation. Chemical diffusion is a slow process; as a con-
sequence, virtually all the embedded viruses are protected from
disinfection.
90
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DISINFECTION: OZONATION
INTRODUCTION
Ozone, an allotropic form of oxygen, is a powerful oxidizing
agent for the disinfection of wastewater. Ozone is used in over
100 municipalities in Europe for disinfection of drinking water.
Certain chemical features make ozone treatment a particularly
attractive method of water purification:
It is a powerful oxidant which reacts rapidly with most
organic compounds and microorganisms in wastewater.
It does not impart taste and odor to potable water.
It is produced from oxygen in air by means of electric
energy.
On the negative side, the cost of ozonation is not presently
competitive with chlorine disinfection. Moreover, long-term
residual disinfection capabilities are lacking, and the insta-
bility of ozone generally necessitates its generation on site
( 660 ).
The principal ozone decomposition products in aqueous
solution are molecular oxygen and the highly reactive free
radicals HOo, OH", and H+. Very little is known about the sig-
nificance of the free radical intermediates on the germicidal
properties of ozone solutions. The same free radicals are pro-
duced by irradiation of water, and it has been reported that
HOs and OH~ radicals contribute significantly to the killing of
bacteria by this process.
As seen in Table 48, a considerable amount of information is
available on the destruction of various pathogens by ozonation,
however little information was found on the effect of ozone
upon other contaminants.
WATER QUALITY PARAMETERS
Because of its strong oxidizing character, ozone is very re-
active toward the organic compounds which make up the BOD, COD,
and the total organic carbon. Under ideal conditions the reac-
tions would result in almost complete oxidation and only carbon
dioxide as a reaction product. In practice, ozonation results
91
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TABLE 48. LITERATURE REVIEWED PERTAINING TO OZONATION
Contaminant
Reference Number
Water Quality Parameters
Ammonia
BOD
COD
Nitrates
Nitrites
Phosphates
Suspended solids
Total organic carbon
Others (general )
Elemental Contaminants
Biological Contaminants
Adeno virus
Bacteria
Clostridium
botulinium
Coliforms
Coxsackie virus (A&B)
ECHO virus
iicjierichia cojj[
Fecal streptococci
Parasitic worms
6, 244, 332, 353, 545
170, 171, 353, 427, 463, 474
127, 170, 244, 351, 474, 571
244, 332, 474, 545
244, 332, 353, 545
474
244
474, 587
207
227, 228
49, 110
6, 34, 110, 170, 171, 243, 283,
351 , 353, 556
660
171 , 244, 351, 402, 673
110
110
34, 49, 343, 344, 351, 660
34, 351
444, 660
92
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TABLE 48 (continued)
Contaminant
Reference Number
Biological Contaminants
Polio virus
Salmonella
Virus
Other (general)
110, 118, 343, 344, 409
351
49, 50, 51, 110, 152, 170, 259,
400, 402, 508, 509
343
93
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in only partial oxidation and produces simpler organic molecules.
Both Ghan and Nebel reported COD removals of less than 40
percent. Morris found that the apparent BOD of a wastewater can
increase after ozonation as a result of refractory organic
molecules being oxidized to simpler, biodegradable compounds.
If the ozone is applied after other treatment processes (as is
normal), the increase in organic nutrient molecules can lead
to the growth in the distribution system of algae, slime
bacteria, and the possible regrowth of any pathogens not des-
troyed during treatment.
Ozone is effective at decreasing concentrations of organic
suspended solids and organic nitrogen through oxidation.
Ozonation can assist in suspended solids removal through froth
flotation mechanisms induced through the process. Ozone will
also oxidize nitrites to nitrates, but will not react with
ammonia ( 332 ). There is little evidence to date that ozona-
tion will produce any toxic or carcinogenic oxidation by-products
as will chlorination.
ELEMENTAL CONTAMINANTS
Furgason and Day ( 228 ) studied the feasibility of
ozonation for iron and manganese removal from raw water with
relatively high input concentrations. The study demonstrated
that ozone effectively oxidized the iron and manganese to
an insoluble form which could be filtered from the water.
Complete oxidation of the minerals required a reaction time
of 30 sec. Filtration studies indicated a relatively fine
medium was required to remove the oxide precipitate.
BIOLOGICAL CONTAMINANTS
The use of ozone as a wastewater disinfectant was reviewed
by Venosa ( 660 ). It was concluded that with 0.1 mg/fc of active
chlorine, 4 hr would be required to kill 6 x 10^ E. co1i cells
in water, whereas with 0.1 mg/£ of ozone only 5 sec would be
necessary. When the temperature was raised from 22°C to 37°C,
the ozone inactivation time decreased from 5 sec to 0.5 sec.
These investigations revealed that the contact time with ozone
necessary for 99 percent destruction of E. coli was only one-
seventh that observed with the same concentration of hypochlo-
rous acid. The death rate for spores of Bacillus species was
about 300 times greater with ozone than with chlorine.
In the same study, Venosa also described bacteriological
studies performed on secondary effluent from an extended aera-
tion pilot plant in the Metropolitan Sewer District of Louisville,
Kentucky. Using an average applied ozone dosage of 15.2 mg/«,
for an average contact time of 22 min, fecal coliform reductions
of greater than 99 percent were achieved, resulting in a mean
94
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fecal coliform concentration of 103 cells/100 mi , a mean
total coliform concentration of 500 cells/100 mi , and a mean
fecal streptococci concentration of 8 cells/100 mi in the
final effluent. Laboratory results with raw sewage indicated
that ozone could be successfully used to sterilize sewage
containing Bacillus anthracis , influenza virus, and B. s u bt i1i s
morph. g1o b i b i i , and to inactivate toxins of Clostridium
botul i num. Ozone consumption was 100 to 200 mg/i for 30 min.
Finally, Venosa found ozone to be many times more effective
than chlorine in inactivating poliomyelitis virus. Identical
dilutions of the same strain and pool of virus, when exposed
to 0.5 to 1.0 mg/i of chlorine and 0.05 to 0.45 mg/i of ozone,
were devitalized within 1.5 to 2 hr by chlorine, while only
2 min of exposure were required with ozone.
Majumdar et al . (409) also studied the inactivation of
polio virus by ozonation and concluded that the inactivation
is not totally complete. Results are summarized in Table 49 .
TABLE 49 . SURVIVAL OF POLIO VIRUS IN
OZONATION CONTINUOUS FLOW STUDIES (409)
Ozone Residence Average
Type of Concentration Time Survival
Mastewater (mg/£) (min) (percent)
Primary
wastewater 0.84 8.0 1'.820
1.47 2.0 '0.016
4.44 1.0 0.006
Secondary
wastewater 0.79 8.0 2.055
1.77 2.0 0.013
5.05 1.0 0.006
Pavoni and Tittlebaum (508) recently studied ozone
disinfection of viruses in the Fort Southworth Pilot Plant
of the Metropolitan Sewer District in Louisville. Using
F2 bacteriophage as the model virus, they demonstrated virtually
100 percent inactivation efficiency in the secondary effluent
after a contact time of 5 min at a ozone dosage of approximately
15 mg/i and a residual of 0.015 mg/i . Of particular interest
was the observation that the rate of inactivation was greater
for F2 bacteriophages than bacteria. In addition, the following
conclusions were reached:
1. F2 virus concentrations were shown to be unaffected
by the flow or mixing of the ozone reactor.
95
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2. F2 virus was inactivated with virtually 100 percent
efficiency after a contact time of 5 min at a total
ozone dosage of approximately 15 mg/a and a residual
of 0.015 mg/a .
3. E. coli bacteria and F2 virus were inactivated with
virtually 100 percent efficiency after a contact time
of less than 15 sec in the absence of ozone-demanding
material .
4. An extremely small number of viral particles was
observed in effluent studies.
5. Oxidation by ozone appears to be the mechanism of
kill for bacterial cells and viral particles. Ozone
is theorized to act as a general oxidant causing
cell lysis and the release of soluble COD.
Mercado-Burgos et al. (444) examined the effect of ozone
on Schistosoma ova, concluding that the process was ineffective
96
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SECTION 7
LAND/GROUNDWATER
INTRODUCTION
Hundreds of municipal and industrial wastewater treatment
plants dispose of their effluents to the land, as illustrated
in Figure 2 . Thousands of wastewater lagoons percolate
effluents into the ground. Millions of septic tank systems
leach their wastewater into the ground. Most of these waste-
waters travel through the soil and eventually reach groundwater
aquifers. Unplanned groundwater recharge with wastewaters,
therefore, must be recognized as occurring on a large scale.
MUNICIPAL 6.INDUSTRIAL
WASTEWATER LAND
DISPOSAL
WASTEWATER
PONDS
SEPTIC TANK
SYSTEMS
USEABLE GROUNDWATER AQUAFERS
Figure 2. Unplanned wastewater reuse exists
for many groundwater supplies.
97
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The present interest in planned regulated wastewater
reuse projects is bringing into focus an informal practice
which has existed "in the closet" for a long time. The question
is not whether wastewater reuse is acceptable, but rather how
best to control what is an existing practice.
Groundwater recharge with treated municipal wastewater is
accomplished by either planned or unplanned processes. Planned
processes consist of two basic methods (Figure 3 ) The
simplest and most widely used consists of conveying'the treated
effluent to shallow spreading basins and allowing the water to
percolate through the soil to the groundwater. The second
planned method consists of conveying the effluent to a well
field and injecting the water directly into the aquifer. The
major intent of these formal processes is to replenish ground-
water basins, to establish saltwater intrusion barriers in
threatened coastal aquifers, or to provide further treatment
for ultimate extraction and reuse.
Unplanned recharge, as previously noted, accounts for much
greater amounts of wastewater reaching groundwaters and
includes percolation from irrigation and holding ponds and
leachate from septic tanks.
Many variables affect the potential for a public health
hazard from land disposal. These include:
The characteristics of the wastewater disposed;
The rate of waste application;
The hydrogeological characteristics of the
disposal site;
The method of disposal, e.g., crop irrigation,
land spreading, percolation ponds, sanitary
landfill, etc.;
Proximity of public access;
Utilization of groundwater potentially
affected; and
Local climate.
The above listed variables are not mutually exclusive-
they interact in many ways to influence the rate and extent
of transport of contaminants from each source and to influence
the importance of each potential pathway. It is beyond the
scope of this report to delve deeply into the science of waste
application technology. This subject is being researched
98
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SHALLOW BASINS
GROUND
TREATED
WASTEWATER
w _ %****' *»,
«Q/>tt°0.' '
e o» . o '° oe9 o o 0° " o
°a?-. 'o0o0:'o<>°a0'\'°>0-*o°°o°°
" 0 C.O°o0oOo0o ° 0 . °e
. ' ' o o° o o ,'oo'» o o i". o>'
±
, ° . o ' o<>
O o 0 , ,
M O V
0«*.0.'o0oo;««
'" °o O ° o«"0
) 0 0 0 «» t 0
-a«r
GROUND
c°o' C
o . o 0~ 0~ O ~ O
' " "0°0- o 00,0 0.0<.
'--"a o°'0V o'»'*\
0. 00^0
0 ,
GROUNDWATER AQUAFER
PLANNED RECHARGE BY DIRECT INJECTION
Figure 3. Methods of planned recharge.
99
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heavily by the EPA and other agencies to establish guidelines
for the safe land disposal of effluents. This report will,
however, discuss the current knowledge about associated
potential public health problems.
Literature reviewed concerning wastewater disposal to
land has centered on groundwater elemental and biological
contaminants, and water quality parameters providing plant
nutrients, such as nitrogen and phosphorus forms. The increased
use of wastewater application to land has created a need for
increased research into the dynamics of wastewater contaminants
in soil systems. It is necessary to study the capabilities of
these systems to destroy, neutralize, remove, concentrate, or
otherwise affect applied wastewater contaminants.
A number of factors determines the degree to which ground-
water may be contaminated by wastewater that is applied to
land. Depth to the groundwater table and distance to an
extraction point affect residual levels of phosphorus, bacteria,
and other constituents for which removal appears to be a func-
tion of travel distance. Soil characteristics, native ground-
water quality, assimilation capacity of the aquifer, and method
of waste application also determine groundwater degradation
and consequent health problems (568). Cation exchange and
adsorptive capacities important in the removal of metal ions
and viruses and of trace organics and solids are determined by
soil composition. Porosity regulates infiltration rates to
some extent, affecting contaminant residence time in surface
layers. Residence time may, in turn, determine aerobic or
anaerobic conditions.
Total groundwater volume cannot necessarily be considered
an effective diluting agent. Uniform diffusion of recharged
water cannot be guaranteed, and water quality may vary
considerably both in area and in depth.
WATER QUALITY PARAMETERS
Research in this area has been principally concerned with
nitrogen and phosphorus forms entering groundwater as a result
of land application of wastewater. Removal of suspended solids
from wastewater effluent has also received attention.
The problems and transformations associated with nitrogen
forms in soils are relatively well known. Organic nitrogen
and ammonia, when applied to soils under normal aerobic condi-
tions, are rapidly converted by nitrifying bacteria to nitrite
and nitrate. Both of these anionic forms move through soils
in percolating water with little difficulty. Under anaerobic
soil conditions, on the other hand, the process of conversion
to nitrite and nitrate is inhibited. Ammonium ions and free
100
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ammonia persist and are held near the soil surface by adsorption
onto soil particles, by cation exchange reactions, or by fixa-
tion in clay lattices.
In an acidic environment, nitrite has been found to react
with secondary amines to produce nitrosamines. These compounds
have recently been labeled carcinogenic, teratogenic, and
mutagenic. The health hazards associated with nitrite and
'other forms of nitrogen in drinking water and crops have been
delineated by the U.S. Department of Agriculture (663).
The most definitive study of nitrogen removal by land
application of wastewater effluent was conducted by Herman
Bouwer at Flushing Meadows, Arizona ( 73). He found that short
flooding periods (two days flooding followed by five days dry-
ing) did not provide sufficient time to develop the anaerobic
conditions for nitrate denitrification. A longer flooding
period of ten days followed by two weeks of drying proved to
be more favorable. With this schedule, oxygen in the soil was
depleted during flooding, causing nitrogen (in the ammonium
form) to be adsorbed by the clay and organic particles. Flood-
ing was stopped before the cation exchange complex in the soil
was saturated with ammonium. Upon drying, oxygen entered the
soil, and ammonium was nitrified under aerobic conditions to
nitrate. Concurrently, some of the nitrate formed was denit-
rified, in micro-anaerobic pockets in the otherwise aerobic
upper soil zone, to nitrogen gas that escaped to the atmosphere.
When flooding was resumed, if the basins were immediately
flooded to a depth above 1 ft, the nitrates were quickly
leached out of the top few feet of the soil to groundwater.
However, if initial flooding was shallow (a few inches deep),
the lower head allowed a low infiltration rate, a larger nitrate
retention time in the microbiologically active soil zone, and
further denitrification. At these lower initial hydraulic
loading rates, nitrogen removals were as high as 80 percent.
However, if high application rates were consistently maintained,
nitrogen removal was only 30 percent with a peak nitrate surge
to the groundwater after the start of each new flooding cycle.
A study by Preul (532) in 1966 provided the following
observations of the movement and conversion of nitrogen in
soil and the potential dangers of nitrate contamination:
1. Biological oxidation is the dominant mechanism
affecting ammonia nitrogen as it passes through
the soil. This action initially occurs at a
high rate, and to a large extent, within several
feet of the point of release of the septic tank
effluent, if soil conditions are well aerated.
101
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2. Nitrate contamination of groundwaters is a
serious threat from shallow soil adsorption
systems. High concentrations of ammonia
nitrogen in septic tank effluents are quickly
nitrified to high concentrations of nitrate,
which pollute the groundwater. Dilution from
groundwater or soil moisture and possibly
denitrification aid in the deterrence of
ni trate.
3. The effectiveness of adsorption in deterring
the travel of nitrogen is limited, because of
the rapid conversion of ammonia to nitrate.
Laboratory experiments have shown that ammo-
nium can be readily removed in soil by adsorp-
tion; but, under aerated soil circumstances,
nitrification of these ions occurs before the
flow can contact a sufficiently effective
volume of soil.
Similarly, results of a study by Chapman et al. (115) have
shown that, in Texas, irrigation with a sewage effluent was a
potential source of nitrate pollution of the local groundwater.
The results indicated that nitrification of ammonia nitrogen
in the effluent is rapid and complete, taking place within the
top 3 ft of soil. It was concluded that substantial amounts
of nitrate would not be fixed by the soil and that, at a 3-in
per week application rate, appreciable amounts of high nitrate
water would percolate to the groundwater. Selective crop
production of grains and grasses having high nitrogen uptakes
(corn, bermuda grass, oats) was deemed the most effective
method of protecting the groundwater.
Short daily flooding schedules evidently result in highly
efficient nitrification to nitrate. Me Michael and McKee (441)
reported data from test basins in the Whittier Narrows and the
Rio Hondo spreading grounds near Los Angeles, California.
These basins, equipped to collect water at 2-, 4-, 6-, and
8-ft depths, received treated wastewaters on a daily basis
using a short period of flooding and a longer period of drying.
This cycle ensured completely aerobic conditions. Studies
indicated that almost all the nitrogen had been converted to
the nitrate form at depths of 8 ft.
Intermittent and continuous spreading of secondary effluent
at the Hyperion Treatment Plant (572), in Southern California,
resulted in the nitrogen transformations shown in Table 50.
102
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TABLE 50 . NITROGEN TRANSFORMATIONS RESULTING FROM
DIFFERENT SPREADING TECHNIQUES (572 )
I.
Under continuous
spreading:
Effluent applied
II.
Percolate from 7-10 ft
below ground (mg/-)
Under intermittent
spreading:
Effluent applied
Organic-N Ammonia-N Nitrate-N
7.1-8.5 15.5-17.5 0.2- 0.8
1.2-2.7 8.7-18.5 5.2-18.1
Organic-N Ammonia-N Nitrate-N
2.3-3.6 4.9-27.9 0.1-14.2
Percolate from 7-10 ft
below ground (mg/£)
1 .1-2.1
0.0- 0.7 8.4-22.4
A study ( 572 ) conducted at the sewage farm in Arroyo Grande,
California, indicated the pulse-like effect of intermittent
spreading on the nitrate level in the percolate. During weekly
flooding of the field with settled sewage effluent, the upper
foot of the soil adsorbed 2,840 Ib of organic and ammonia nitro-
gen/ac. As the fields drained and were exposed to oxygen, this
adsorbed nitrogen was rapidly converted to nitrate, resulting
in nitrate levels of 1,000 to 2,000 mg/£ in the soil solution
of the top foot. Consequently, the subsurface drainage water
exhibited pulses of higlj nitrate concentration
began. After all the nitrate was leached from
the applied wastewater, the nitrate content of
returned to a low level.
when flooding
the topsoil by
the drainage water
When the South Tahoe Public Utilities Department sprayed
treated sewage on forested hillsides in the fall of 1963,
nitrogen removals by the soil mantle were more than 65 percent.
The removals dropped to 26 percent in the winter when the ground
was frozen. Significant amounts of ammonium ion were present
in the upper 4 in of soil, but nitrate levels were low
at all depths. The removal of nitrogen was attributed to the
denitrification in the soil mantle under anaerobic conditions
(572 ).
The California State Health Department ( 572) reviewed
nitrogen removals and management at a number of well-injection
waste disposal/recharge systems. Results of a six-month study
on the injection of slow sand filter effluent are shown
in Table 51 .
103
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TABLE 51 . NITROGEN TRANSFORMATION IN RECHARGE
AQUIFER. MG/l ( 572 )
Organic-N Ammonia-N Nitrite-N Nitrate-N
Natural water in
the aquifer
Filter effluent
before injection
Recharged water in
aquifer, 20 ft
from injection well
Recharged water
mixture in aquifer,
500 ft from injec-
tion well
,4-. 5
2.2
1.4
.2
1.5
1.2
.9
.8
0.0
.01
.21
.4-4.8
21 .3
18.2
.003
6.1
As can be seen from this table, intermittent spreading
techniques maintained aerobic conditions in the soil, making
possible the oxidation of ammonia and organic nitrogen to nitrate.
Under continuous spreading, anaerobic conditions prevailed, and
ammonia was still present in significant concentrations at a
7- to 10-ft depth.
When a low-rate application system is used, the amount of
nitrogen applied to soil with sewage effluent is not much more
than can be removed by crops, according to Bouwer (72 ). A low-
rate system involving application to wheat at 2.5 and 5 cm/week
was cited. At the lower application rate, 92 percent of the
nitrogen in the wastewater was removed in the soil, while at the
5 cm/week rate, 60 percent was removed. On the other hand, when
animal waste slurries or other wastewater with a relatively high
nitrogen content are applied, the amount of nitrogen supplied
may far exceed that which can be utilized by crops. To obtain
significant nitrogen removal under these circumstances, Bouwer
suggests that the system be designed to stimulate denitrification
in the soil. He cites an instance where this was done by install-
ing an artificial barrier to water movement at a depth of 2 m,
causing the formation of an anaerobic region. Ammonia and organic
nitrogen in applied wastewater were converted to nitrate in the
upper, aerobic region of the soil, which was then denitrified
in the lower, anaerobic zone. The system removed 96 to 99 percent
of the total nitrogen applied at rates of 1 to 2 cm/day.
104
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Analysis of data in Table 50 indicates that the decay
of nitrate in the aquifer was due to some extent to denitri-
fication, as well as dilution. Considering such decay, the
nitrate nitrogen level was expected to fall to 10 mg/£ before
traveling a distance of 500 ft in the aquifer. Further tests
revealed an anaerobic, microbiological ly active zone in the
aquifer in the vicinity of the injection well. During the
tests, nitrate was largely removed by microbial denitrifica-
tion within 150 ft of the injection well.
In summary, data indicate that, under proper management
conditions, land application of wastewater effluent offers
the potential to efficiently remove nitrogen from wastewater
and protect groundwater from nitrate contamination. The most
successful programs stressed an appropriate flooding/drying
schedule to promote both aerobic nitrification and anaerobic
denitrification processes, in order to ultimately convert
ammonia nitrogen in the wastewater to nitrogen gas. However,
if not properly managed, a definite danger exists of polluting
groundwater resources with excess nitrates.
Recent studies of land application of wastewater effluent
indicate that the soil system is highly efficient in removing
phosphates from wastewater. Phosphate removal is both a
function of soil composition and travel distance. In most
soils, phosphorus not taken up by plants is immobilized due
to the adsorption of phosphate onto the soil. Adsorption -!s
followed by precipitation into various forms of calcium
phosphate if the soil is basic (72 ). These reaction products
are sufficiently insoluble, so that phosphorus is held in the
upper few centimeters of most soils, and very little phospho-
rus moves into the groundwater (388). However, in the case
of acidic, sandy soils with no iron or aluminum oxides, little
phosphate is fixed. Thus, it may be necessary to remove
phosphorus from wastewater before its application to such
soils (72 ).
Hook, Kardos, and Sopper (299) reported that, under proper
management, most of the phosphorus in wastewater remains in
the soil at the disposal site or leaves as a nutrient in
harvested crops. They found that soils differed in their
abilities to retain phosphorus. In a heavy-textured soil high
in iron and aluminum oxides and hydroxides (sesquioxides),
phosphorus from effluent irrigation did not increase in the
soil below a depth of 1 ft after 7 yr of irrigation. In a
light-textured soil with half as much sesquioxides, phosphorus
content increased to a depth of 3 ft after 6 yr of treatment.
Phosphorus removals at Flushing Meadows, Arizona (73 ),
were found to be basically dependent upon the distance traveled
by the wastewater through the soil. The chief removal mechanism
105
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was precipitation as calcium phosphate or magnesium ammonium
phosphate, since the soils tested contained little iron,
aluminum oxides, or other phosphate fixing materials Under-
ground travel distances of 30 ft produced 50 percent reduction-
distances of several hundred feet were found to be sufficient '
for 90 percent phosphorus removal. However, the capacity of
the soil to remove phosphorus decreased after the start of the
project, holding stable at approximately 50 percent removal.
The fact that soils gradually lose their capacity to adsorb
phosphates over long-term application is substantiated by
Barrow's detailed analysis of this phenomenon (30). He
concluded that previously applied phosphate had been converted
to a form that was occupying phosphate adsorption sites, thus
reducing the capacity of the soil to further adsorb phosphate.
Continuing studies at Lake George, New York ( 22 ), have
shown that significant amounts of nitrates appear to reach
the waters tributary to the lake. However, the wastewater
land treatment system appears to remove essentially all phos-
phorus, thus reducing the potential for algal bloom in the lake.
Dugan et al.(185), in their work on land disposal of
wastewater in Hawaii, noted that phosphorus removals of over
95 percent within a 5-ft depth of percolation were obtained
when secondary wastewater was applied to grassed areas.
Suspended solids are removed very effectively by land
application systems. In fact, one problem encountered in the
spreading of wastewater is that nearly all suspended solids
are filtered out in the top few inches of soil. This can cause
clogging of soil pores and reduction of infiltration rates.
There is no danger of groundwater contamination in applied
wastewater from suspended solids. Literature data on suspended
solids are not extensive, because experience has shown land
application to be capable of removing virtually all solids at
the surface. A study at Whittier Narrows, California (572),
showed suspended solids removal, due to percolation, of 95 per-
cent. At Flushing Meadows ( 73 ), the suspended solids concen-
tration of the percolate was essentially zero, even though
the solids in the wastewater applied reached 100 mg/£. Similar
findings were reported at Lake George ( 22 ), where virtually
all BOD and suspended solids were removed from percolated
effluent.
Results from a spray i rrigation and runoff system used to
dispose of a cannery waste ( 45 ) showed that even with a run-
off-type system, suspended solids removals averaged 97 percent
Dugan et al. ( 185) reported similar high suspended solids
removals with application of secondary effluent to Bermuda
grass in Hawai i.
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ELEMENTAL CONTAMINANTS
Municipal wastewater contains small amounts of nearly all
metals. The degree to which a particular soil will protect-
underlying groundwater through removal of contaminants is
primarily determined by the chemical and physical composition
of the soil. Removal can occur through such processes as
precipitation of solid phases, ion exchange, and adsorption.
These processes are in turn controlled by soil pH, the
oxidation/reduction potential, clay content, the presence and
type of organic material, and the extent of soil saturation.
The general nature of reactions of sewage wastes with
soil is well known. With time, wastes applied to land are
broken down, and the dissolved constituents become part of
the soil solution. Released cations can exchange with those
already on exchange sites in the soil. Metals as ions or in
the colloidal state can be adsorbed onto soil surfaces. When
the levels of ions in solution exceed the solubility of
corresponding solid phase compounds and minerals, those
compounds can precipitate. When the solubility of solid phase
compounds and minerals exceeds the levels of corresponding ions
in solution, the compounds can dissolve. Constituents are also
ingested by soil microorganisms and incorporated into soil
organic matter.
Ions that are not removed by any of these processes, but
that remain in the soil solution, are available for uptake by
plant roots or leaching by water moving through the soil
profile. Lindsay (388) studies the composition of the soil
solution, concluding that it is controlled by the solubilities
of solid phases. Thus, precipitation and dissolution reactions
determine the activity of ions in solution, which in turn
governs ion exchange.
Lindsay (388) also recognized the importance of the
formation of metal-organic complexes and chelates in increasing
the solubility and mobility of metals in soils. Brown (79 )
stressed this point. He found that it is misleading to predict
the availability of metals in soils from their solubility in
distilled water. He cites evidence that plant uptake of metal
ions could not be predicted by the water solubility of the
solid compounds. This may be because the soil solution in the
vicinity of roots, unlike distilled water, is mildly acidic and
contains organic metal-complexing agents (388).
All of the trace elements for which water quality criteria
have been established may occur as either soluble or insoluble
metal-organic complexes (615). Low molecular weight organic
molecules tend to increase the penetration of complexed metal
ions into the soil, while high molecular weight molecules and
their complexed ions may be filtered out by the soil (72 ).
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The chemistry of the metal organic complexes is complicated,
and present knowledge of organic forms of the elements is
insufficient to generalize. Where concentrations of trace
elements in soil solutions are in excess of those predicted from
inorganic solubility product considerations, the element is
thought to occur in organic form. Because of this lack of know-
ledge, the literature discusses mainly the chemistry of inor-
ganic forms. This is unfortunate because most of the metal
ions in wastewater and sludge probably occur in complexed
form.
Most metals are less mobile under aerobic and basic soil
conditions than they are under anaerobic and acid conditions
(72 ). The neutral water extract of soils contains less
heavy metals than acidified extracts of the same soils, indi-
cating the importance of the pH factor in influencing the
mobility of metals (533). Lindsay (374) cites evidence that
for zinc and copper there is a 100-fold increase in ionic
activity for each unit decrease in soil pH. Normally insoluble
metals may become mobilized in the event of a change in the
characteristics of percolating water, such that acidic or
anaerobic conditions occur.
The removal of metals by ion exchange or adsorption depends
upon the availability of exchange and adsorption sites in the
soil as well as on the factors (ionic activity and pH) just
discussed. Therefore, the clay content of the soil is important;
clay soils provide more exchange and adsorption capacity than
sands and gravels (552). A correlation also exists between the
form in which the elements occur in solution and their removal
by exchange or adsorption. In general, elements that occur in
solution as anions or neutral molecules pass through soils
more readily than do elements that occur as cations. Inorganic
arsenic, selenium, and fluorine in aerated soils occur as
anions or neutral molecules. Although there are exceptions
(depending upon the chemistry of the system), inorganic cadmium,
copper, chromium, lead, mercury, silver, and zinc most commonly
occur in fresh waters and soil solutions in the inorganic
form as cations (615).
Only one reference was located that provided experimental
data on cadmium in relation to wastewater applied to land.
At Flushing Meadows, Bouwer ( 73 ) found that cadmium in waste-
water applied to land in shallow basins showed very little change
due to migration through the soil. The cadmium concentration
dropped only slightly from 7.7 yg/£ to 7.2 ug/£. Aerobic
conditions and alkaline pH prevailed in the soil studied. A
study (615) by the California State Water Resources Control
Board (CSWRCB) reviewed available data on soil reduction of
cadmium in effluents, concluding that information is not
sufficiently detailed to allow adequate evaluation of cadmium
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concentrations in water reaching g>oundwater basins. According
to the study, it must be demonstrated that a particular soil
is able to reduce the concentration of cadmium to a level that
is acceptable for drinking water. Otherwise, the study advised
against the use of wastewater effluents with concentrations
above this limit for groundwater recharge operations involving
percolation through soil.
Bouwer's work at Flushing Meadows ( 73 ) found that the
copper concentration of applied wastewater was reduced about
86 percent by passage through the soil. This removal occurred
rapidly, usually in the first 30 ft of downward flow.
Iron and manganese in wel1-oxidized soils are characterized
by the formation of highly insoluble oxides and hydroxides.
However, at low pH and under reducing conditions, these metals
can be solubilized and become mobile in the soil as Fe^+ and
Mn2+. Amramy (15) conducted a study of sewage lagoon effluent
spreading on sand dunes. He found that after a subsurface
travel distance of 8 m, the concentration of iron in the waste-
water actually increased from 0.28 mg/£ to 0.57 mg/£. The
manganese concentration increased from 0.08 mg/£ to 0.19 mg/£
after 25 ft of travel through sand. Wesner and Baier ( 685)
found a similar phenomenon when tracing the underground move-
ment of wastewater after injection. Over a travel distance of
400 or 500 ft, the concentration of iron did not change.
Manganese concentrations, on the other hand, increased up to
300 percent in the first 100 ft of subsurface travel. Anaerobic
conditions, favoring formation of soluble manganese compounds,
are mentioned as the possible cause of the large increase.
These conditions are most likely caused by biological oxidation
depleting oxygen near the point of injection, thus causing the
reduction of manganese to soluble forms. However, after
greater travel distances and the return to aerobic conditions,
the manganese may revert to insoluble compounds and be removed
from the migrating water.
Ragone, Vecchioli, and Ku (535) reported on deep well
recharge experiments conducted in Nassau County, Long Island.
Tertiary effluent was recharged by a deep well into the Magothy
aquifer, the primary water supply source for Nassau County.
As of September 1972, 12 recharge tests had been run since the
inception of the recharge program in September 1968. Although
the iron concentrations of reclaimed and native water averaged
0.44 mg/£ and 0.24 mg/£, respectively, the iron concentration of
the mixed (native and reclaimed) water at times exceeded 3 mg/£.
The authors mentioned several sources that could account for
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the increase in iron concentration, but the most probable source
was the pyrite native to the Magothy aquifer. During recharge,
the natural reducing condition in the aquifer was replaced by
a progressively more oxidizing environment. The initial
response to this change was the oxidation of pyrite, which
released Fe+2, 504-2, and H+ into solution. Eventually, ferric
hydroxide precipitated, and the Fe+2 concentration decreased.
The exact oxidation mechanism apparently involved inorganic
and/or organic constituents in the reclaimed water, because
water from the public potable water supply system caused no
increase in iron concentration when injected into the aquifer.
The Flushing Meadows study by Bouwer (73 ) contained data
on the reduction of lead by soil infiltration. Bouwer found
that the wastewater concentration of lead decreased by 20 percent
after significant travel distance underground. Apparently, a
small portion of the lead was tied up rapidly (within 50 ft),
while the majority was unaffected by further travel. It should
be noted, however, that the soil examined in these experiments
was a sand with limited adsorption and exchange capacity for
many trace elements.
Both mercury and zinc form insoluble compounds in soil,
lowering the activity of the ions in solution so that little
movement occurs. Mercury is particularly insoluble as phosphate,
carbonate, or sulfide. However, under low pH conditions, the
metals may become mobilized. They can also form soluble
complexes that affect their mobility under certain circumstances
(388). At Flushing Meadows (73 ), underground percolation
through 100 ft of sand produced 40 percent removal of mercury
and approximately 58 percent removal of zinc. Further travel
produced no further removal of mercury but reduced the zinc
concentration to about 20 percent of that in the applied waste-
water. The final concentrations of mercury and zinc were
.00014 mg/£ and .037 mg/l, respectively.
In conclusion, the information garnered in this study of
the literature is inadequate to define fully the chemical
behavior of elemental contaminants in the soil and their fate
as they percolate through the unsaturated zone. The CSWRCB
recommended, on the basis of its literature review (615 ), that
wastes containing concentrations of certain metals above those
acceptable for drinking water supplies should not be applied -to
land, unless it can be demonstrated that contamination of
groundwater does not occur.
BIOCIDAL CONTAMINANTS
Use of chemical pesticides in agriculture generated
many studies of, the potential harmful effects of these compounds
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on land, crops, surface water, and groundwater. However, there
is little data available on biocides in municipal wastewater or
on the potential dangers of groundwater contamination through
land wastewater application operations. This lack of informa-
tion is understandable considering the minimal role that munici-
pal wastewater plays in transporting biocides to the land and
groundwater. Biocides come in contact with the land through a
number of activities, primarily by direct application to the
land for pest control. Return irrigation water, and spills and
wastes from pesticide manufacturing operations also bring
biocides in contact with the land.
The reactions of pesticides with soil has received limited
attention in the literature. Volatilization, chemical degrada-
tion, and absorption by plant roots and seeds apparently remove
a small portion of pesticides reaching the soil. A more signi-
ficant process for pesticide removal may be microbiological
degradation. Although this process is very slow in some cases,
often taking several years, microbiological degradation accounts
for the breakdown of a remarkable variety of organic compounds.
Pesticides that are not removed from the soil column or broken
down by these processes may be available for leaching into
groundwaters.
Gerakis and Sficas (239) reviewed the literature on pesti-
cide.degradation and leaching They reported that the most
important factors involved in these two processes are soil
temperature and moisture, organic matter and clay content,
soil management practices, pH, and species and population
density of microorganisms present. The presence of organic
matter and clay in the soil appears to be positively correlated
with adsorption of pesticides onto soil particles.
Van Bladel and Moreale (658) studied herbicide adsorption
onto clay minerals. They found that adsorption increased
with the polarizing power of the exchangeable cation, and
concluded that adsorption appears to be one of the most impor-
tant factors in reducing pesticide removal from soil layers
by leaching.
Gerakis and Sficas (239) cite evidence that pesticides
differ in their mobilities in the same soil. One study showed
that (1) acidic compounds are relatively mobile, (2) phenyl
ureas and triazines are of intermediate to low mobility, and
( 3 ) organochlorine compounds and organic cations are least
mobile. Further data that were reviewed supported the conclu-
sion that under normal agricultural practices and rainfall,
it is very unlikely that pesticides may be leached deeply
enough and in such quantities as to cause appreciable contami-
nation of groundwaters.
Ill
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A California State Water Resources Control Board report
(615) mentioned that pesticides are adsorbed by soil clays,
iron aluminum oxides, and especially by organic colloids, and
that they are susceptible to microbial decomposition. However,
the amount of biocides in average municipal wastewater was
found to be so minimal that the spreading of municipal waste
on land offers extremely low potential for groundwater biocide
contamination.
SYNTHETIC/ORGANIC CONTAMINANTS
One of the most intensely debated questions regarding
land application for treatment and/or disposal of municipal
wastewater concerns the problem of residual organic contami-
nants. Refractory organic compounds may survive conventional
treatment processes and penetrate through the soil to contami-
nate groundwater supplies. The controversy centers around
the fate of residual organics within the soil systems, includ-
ing such issues as the synergistic effects between organics
and inorganics or other groundwater and soil constituents, or
conversion of safe organics to hazardous compounds in the soil.
Despite this controversy, no literature was found concerning
groundwater pollution by the synthetic/organic contaminants
in municipal wastewater as a result of land application.
The absence of literature concerning the movement through
soil of synthetic/organic contaminants is not surprising, since
the specific organic makeup of wastewater is unknown. Some of
the chemicals of concern (PCB's, polycyclic aromatics, and
other chlorinated hydrocarbons, etc.) have low solubilities in
water in comparison with vapor pressures. As a result, there
is a distinct possibility of vaporization when wastewaters
containing these chemicals are applied to the land surface.
The California State Water Resources Control Board (615)
cited a study carried out in Colorado that compared the nature
of the soluble organic material in the soil profiles under a
feedlot and under grassland with selected ground, well, and
river waters. It was concluded that the major portion of the
soluble materials in all the waters was polymeric. The soluble
organics under grassland were essentially the same as those
under the feedlot, although phenols were present in greater
abundance in the manure and surface soil of the feedlots. About
13 percent of the soluble material in the soil profiles was
carbohydrate (polysaccharides), and much of the remainder,
based on IR spectra and reductive degradation procedures,
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appeared to be polymerized aromatic structures. This report
by the CSWRCB interpreted these observations to indicate that
the soluble organics under wastewater-treated soils would be
similar to those under feedlot manure or grassland.
BIOLOGICAL CONTAMINANTS
Most available data suggest that
other biological pathogens present in
or inactivated by percolation through
virus, bacteria, and
wastewater are removed
soil.
The California State Water Resources Control Board study
(615 ) provides a summary of the fate of viruses, bacteria,
protozoa, and parasitic worms in wastewaters applied to land.
The summary states that most of these pathogens prefer warm-
blooded animals as their habitat and do not flourish in the
soil environment. When introduced into soils, the pathogens
do not compete well with the vast number and variety of normal
soil inhabitants and are subject to attack by antagonistic soil
species. The time necessary for their ultimate destruction
varies, according to species and environmental conditions.
A compilation of pathogen survival data in t^e literature is
shown in Table 52 below.
TABLE 52. SURVIVAL OF PATHOGENS
IN SOILS (615 )
Ascaris lumbri coides ova
Entamoeba histolytica cysts
Salmonella species
Coliform group organisms
Q-fever organisms
Brucella abortus
Tuberculosis bacteria
Enteroviruses
2.5 - 7 years
8 days
6 hours
133 - 147 days
148 days
30 - 100 days
6 months
12 days
The most persistent pathogens in soils appear to be ova,
cysts, and spore-forming bacteria. The survival of enteric
viruses in soil has not been thoroughly studied. The dependence
of enteric viruses on specific host organisms for reproduction
suggests that they would not multiply and would not be expected
to survive for a long period of time, although survival may,
at times, be long enough to cause public health concern.
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Two-and-a-half years of continuous observation was
conducted of wastewater reclamation by landspreading in Lodi,
California (553). It was found that the MPN of coliform group
organisms, which averaged 1.9 x 10^/100 ml in the wastewater,
was consistently reduced to less than 1/100 ml after 4 to 7 ft
of soil travel. The average percolation rate was 0.3 ft/day
in coarse-textured Hanford sandy loam. It was observed that
the number of coliforms penetrating 1 ft or more was essen-
tially independent of the coliform concentration of the
wastewater.
At Whittier Narrows (441), percolation tests showed that
vertical percolation of wastewater through 4 to 7 ft of soil
is an effective method of removing bacteria of fecal origin,
despite heavy growth of coliforms of soil origin. The forma-
tion of an organic-microbial slime layer at the water-soil
interface was found to increase the efficiency of the filter-
ing action.
Results from studies at Flushing Meadows, Arizona ( 73),
show that fecal coliform density was reduced significantly in
the first 2 or 3 ft of travel. Bouwer found that fecal coli-
form density at a particular depth tended to decrease with
increased flooding time. The peak bacteria density invariably
appeared immediately after flooding was resumed. The concen-
tration of fecal coliforms was consistently decreased to less
than 10/100 ml after 100 ft, and to 0/100 ml after 300 ft of
travel.
A project at Santee, California (569), is famous for
its pioneering work in the reclamation of domestic sewage for
recreational lakes. Travel of secondary effluent through
1,500 ft of very coarse sand was sufficient to remove all
fecal coliforms. Sampling showed that most of the coliforms
were removed in the first 200 ft.
At Orange County, California (685), tests conducted on
a well injection system showed coliform organisms 30 m from
the injection well, but none approximately 80 m from the well.
The results indicated that fecal coliforms are more easily
removed by underground travel than other coliforms. Some of
the other coliforms may have been supported by nutrients in
the effluent.
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Results of percolation tests at Lake George, New York
( 535 ), showed again that percolation of applied secondary
effluent through 5 to 10 ft of soil in two different beds was
sufficient to remove essentially all coliform organisms.
Browning and Mankin ( 83) reported an unusual case of
disease outbreak due to contamination of groundwater well
supplies by land application of treated sewage. In Madera,
California, undisinfected secondary effluent was used to irrigate
a pasture located adjacent to a deep well drawing part of the
city water supply. The wastewater migrated through gopher holes,
filling a construction pit around the well, and eventually
flowed into the well itself.
On the basis of experience and results of full-scale,
long-term wastewater reclamation studies, the CSWRCB (615 )
concluded that, although soil is an excellent media for removing
bacteria, a small fraction of the fecal coliform bacteria there-
in may reach groundwater reservoirs at high percolation rates.
Horizontal travel of viable fecal coliform bacteria in the
aquifer does not appear to occur to a significant degree. The
available data on horizontal travel, however, are inconclusive.
Further inyestigation of the transport and survival of pathogenic
bacteria in groundwater, therefore, is required.
Research shows that travel through soil removes significant
amounts of viruses, primarily through adsorption. Adsorption
is influenced by the pH and ionic strength of the soil solution.
The available information indicates that adsorption of virus
by soil is nearly complete at pH 7 or less, but decreases as
the pH value increases above 7. This is mainly because the
overall electric charge surrounding both the virus and soil
particles becomes increasingly negative as pH levels increase
and, therefore, mutual repulsion occurs (615 ).
It also appears that increasing cationic strength of the
percolating water or soil solution increases virus removal. At
the pH values normally encountered in wastewater, viruses are
slightly negatively charged. The presence of calcium, magnesium,
sodium, aluminum, and other positive ions in the soil solution
decreases the potential for negatively charged soil and virus
particles to repel each other. This results in the formation
of soil-cation-virus bridges that immobilize virions (615).
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The ionic strength in percolating wastewater is usual.ly
sufficient so that it does not limit adsorption. In circum-
stances where ionic strength is significantly decreased,
however, desorption of adsorbed viruses may occur. Organic
matter in wastewater can also compete with viruses for adsorp-
tion sites. In laboratory studies, when virus-adsorbed clay
particles were washed with distilled water, an essentially
complete desorption and reactivation of viruses took place.
In field conditions, other mechanisms in soil systems may
inactivate or destroy adsorbed viruses before they are subject
to desorption (615 ). In addition to pH and ionic strength,
the clay and organic matter content of soil evidently influences
adsorption to some degree. In general, soils of higher clay
and/or organic matter content are more effective in adsorbing
viruses (615).
Definitive work on virus interaction with soil was conducted
at Santee, California, where extensive studies showed that
percolation through several hundred feet of soil consistently
removed all virus from secondary effluent (569 }.
Other studies also supported the conclusion that soil
effectively removes viruses. Viral analyses in Hawaii by Dugan
et al. (185) showed that test soils in 5-ft lysimeters were
completely effective in removing viruses. Brief tests at
Whittier Narrows, California (441), achieved complete removals
of Sabin Type III polio-virus vaccine. Although 250 plaque-
forming units (PFU) of enteric viruses/t were present in the
applied wastewater, no measurable concentrations were found below
2 ft in the percolate.
In 1974 at Flushing Meadows (73 ), virus analyses were
performed bimonthly to determine the fate of viruses in the
soil system. Secondary effluent was allowed to infiltrate into
six parallel horizontal basins consisting of 60 to 90 cm of
fiae loamy sand underlain by several coarse sand and gravel
layers to a depth of 75 m, where a clay layer begins. Observa-
tion wells were installed in line across the basin area. No
viruses were detected in any of the wells at any time during
each flooding period. Gilbert et al. (247) stated that the
failure to detect viruses in the wells indicates that the virus
count was reduced by at least 99.99 percent within 3 to 9 m
of basin soil.
Romero ( 553 ) reviewed the studies performed for the
Department of the Army on sands ranging in classification from
silty sand to coarse-granite alluvium. Results indicated that
the bacterophages Tl , T2, and 65 are more effectively retained
in the finer sands, particularly in those containing a relatively
high percentage of clay and silt. Virus removal was shown to
increase with decreasing particle size. The greatest percentage
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of removal took pla.ce In the uppermost portion of the sand
columns tested. It was shown that for a well-sorted sand of
particle size averaging 0.12 mm, the removal efficiency in 2 ft
of penetration was 99.999 percent.
Young and Burbank ( 708) described studies of virus removal
in Hawaiian soils. In the laboratory, columns of various types
of Hawaiian soil were subjected intermittently to percolating
water with a known concentration of virus (coliphage T4BZ mutant
and polio virus Type II (Lansing) H8), simulating the action of
cesspool leaching. The effluent from each soil column was
analyzed for viral content. Coliphage T4 was applied to
slightly acid soils (pH 5-6) at a concentration of 2.5 x 106/m£.
Percolation through 2.5 to 6 in of soil was 100 percent effec-
tive in retention of the virus. Slightly alkaline soil was
less effective, removing only 67 percent of applied coliphage
and 35 percent of applied polio virus in 15 in. Removal of
polio virus Type II was less complete; 6-in columns were able
to effect only 99.3 percent removal with an initial feed concen-
tration of 1.5 x 10b. pfu/m£.
Wellings et al. (683 ) found that virus can be isolated at
the 6.5 m level below a spray irrigation field. Another study
by Wellings et al. (682 ) measured virus migration through the
ground from chlorinated packaged plant effluent applied to a
cypress dome. Both horizontal and vertical migration was
detected at distances of approximately 7 m for polio and
coxsackie viruses. Wells beyond that distance showed no virus.
The survival of virus within the dome was at least 28 days.
At Fort Devins, Massachusetts, where a land application
site has been in operation for over 30 years, Schaub et al.
(,565 ) studied the removal of bacteria from unchlorinated
primary effluent applied to soil cells. Using tracer f2 bac-
teriophage and the enteroviruses poliovirus I, and EMC virus
it was demonstrated that tracer bacteriophage penetrated into
the groundwater along with the percolating wastewater. The
concentration in the groundwater stabilized at almost 50 percent
of the applied virus concentration. The tracer and entero-
viruses were sporadically detected at horizontal distances up
to 600 ft from the application point.
Lance et al. (369) passed secondary sewage effluent con-
taining 3 x 104 pfu/m£ polio virus Type I (LSc) through 250 cm-
long columns packed with calcareous sand from an area in the
Salt River bed used for groundwater recharge of secondary sewage
effluent. Viruses were not detected in l-m£ samples extracted
from columns below the 160-cm level, but were detected in 5 of
43 100-m£ samples of the column drainage water. Most of the
viruses were adsorbed'in the top 5 cm of soil. Virus removal
was not affected by the infiltration rate, which varied between
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15 and 55 cm/day. Flooding a column continuously for 27 days
did not saturate the top few centimeters of soil with viruses
and did not seem to affect virus movement. Flooding with
deionized water caused virus desorption from the soil and
increased virus movement through the columns. Drying the
soil for one day between applying the virus and flooding with
deionized water greatly reduced desorption, and drying for
five days totally prevented desorption. The investigators
concluded that large reductions (99.99 percent or more) of
virus are expected after passage of secondary effluent through
250 cm or more of calcareous sand, unless heavy rains fall with'
in one day after application of sewage.
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SECTION 8
FRESH SURFACE WATER
INTRODUCTION
Approximately two-thirds of the water supplies in the U.S.
are drawn from surface waters. Direct discharge of treated
wastewater to these fresh surface waters is the most popular
method of wastewater disposal and the most significant pathway
for wastewater contaminants to reach potable water supply
systems. In addition, relatively minor quantities of waste-
water contaminants may indirectly reach fresh surface waters
through runoff or percolation from land disposal of wastewater
effluents. This section of the report discusses current
knowledge about the fate of various effluent contaminants in
fresh-water systems.
Most major river systems in the United States contain
wastewater effluent from upstream municipalities and industries.
the percentage of effluent wastewater volume varying from
negligible to over 10 percent. Potable water systems utilizing
these rivers as a source supply are, of course, reusing waste-
water. Therefore, there is intense interest in the subject of
contaminant changes which may occur in the fresh water system
between waste discharge points and water intake locations.
Much of the material contained in this chapter was derived
from the following references: 162, 211, 239, 326, 534, 591,
and 624.
WATER QUALITY PARAMETERS
General water quality parameters in surface waters are not
of direct public health concern, although they often degrade
the quality of the aquatic habitat. For example, phosphorus
concentrations resulting from sewage disposal contributes to
luxuriant growths of certain algae, such an Anabaena, Nodularia,
or Nostoc - all of which produce toxins that can be harmful to
humans (618, 680 ). However, the tastes and odor also asso-
ciated with such water degradation would generally make the
water unpotable long before the concentration of toxins reached
levels harmful to public health.
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Suspended solids in wastewater can carry adsorbed viral and
other biological contaminants (681). Trace metals occur in
higher concentrations when associated with suspended matter than
when they are in a dissolved state (123), a phenomenon that will
be discussed more fully in the following section on elemental
contaminants. Suspended matter and dissolved organics from
wastewater can affect the natural biological community which,
in turn, affects the nitrogen interconversions and nitrate con-
centrations.
The nitrogen-containing compounds (ammonia, nitrite, and
nitrate) are theoretically hazardous because of nitrate's
association with methemoglobinemia. Ammonia and nitrite nitrogen
can be readily converted into nitrate by chemical or biological
reactions. There are, however, no reported cases of detrimental
public health effects resulting from nitrates in surface waters.
This is because the dilution and natural processes occurring in
surface waters prevent nitrate concentrations from reaching
health impairing levels. There are, however, several reported
cases of groundwater nitrate contamination rising to dangerous
levels. These cases are discussed in the 1 and/groundwater
section of this report.
ELEMENTAL CONTAMINANTS
The behavior of elemental contaminants in fresh-water
systems is very complex. Generally, elemental contaminant
transport mechanisms can be divided into either elements in
solution or elements associated with inorganic or biological
particulates. Each of these mechanisms can be broken down
still further. Dissolved elements may occur as unassociated
ions or as inorganic or organic complexes. Elementals/inorganic
particulate associations include coulombic attraction, as in
conventional adsorption; ionic bonding, as in ion exchange;
precipitated or coprecipitated metal coating; or incorporation
into particulate crystalline lattices. Elementals/biological
particulate associations include surface adsorption, ingested
particulation, and biochemical Incorporation into the organism.
The particular transport mechanism that will predominate in a
given water system depends, in part, on the geohydrologic
environment, mineralogy/petrology of the river or lake bed, pH,
temperature, dissolved organic or oxygen content, biological
activity, elemental type and source, and nonelemental chemical
composition of the water.
This variety of factors does much to explain the seeming
discrepancies in the work of different researchers attempting
to establish element distributions in fresh-water systems.
For instance, Gibbs (246), in his examination of the Yukon and
Amazon Rivers, concluded that precipitated metal coating and
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crystalline incorporation accounted for approximately 90 percent
of the transported iron, nickel, copper, chromium, cobalt, and
manganese (Table 53). Perhac (512), on the other hand, in his
analysis of two Tennessee streams, concluded that 95 percent
of the total stream content of cadmium, cobalt, copper, nickel,
lead, and zinc was in the dissolved state (Table 54). Assuming
that there was no gross experimental error, widely differing
environmental factors must have prevailed.
The complexity of the chemistry, biology, and physics
involved in water behavior of elements precludes a detailed dis-
cussion. Instead, a brief discussion is presented of the more
important aspects of the behavior of elements in water,
followed by a detailed examination of a few sample elements
(mercury, arsenic, lead, cadmium, copper, iron) to demonstrate
the principles involved.
Dissolved elements may occur as unassociated ions or as
inorganic or organic complexes. Of the major elements under
discussion in this report, only barium appears to any great
extent as the unassociated cation; barium ions do not hydrolyze
and form only weak complexes. However, several of the elements
occur as unassociated anions: antimony, arsenic, boron, chromium,
molybdenum, and selenium generally occur in fresh-water systems
as the oxo anion. This is largely because the major sources of
these elements, including wastewater, are rich in the anionic
forms, and because the cationic forms are easily oxidized to the
oxo anion in aquatic systems.
The majority of the dissolved elements normally exist as
inorganic or organic complexes. Table 55 lists the more common
ligands and the conditions and elements normally associated
with them. In relatively pure water, aquo (1^0) or hydroxo
(OH") complexes are formed. At pH levels above neutral, many of
the metal-hydroxo complexes are converted to metal hydroxides or
oxides, which will precipitate out of solution or behave as
colloids.
The other inorganic ligands responsible for keeping metals
in solution in natural waters include carbonate, halides
(notably chloride and fluoride), sulfur species (SH-* sulfate,
and sulfite), and nitrogen species (ammonia, nitrate, and
nitrite). Most of the complexes formed from these ligands are
thermodynamically unstable and appear as transition states
between the free metal ion and a precipitate. The complexes,
however, serve to keep the metals in solution for a time, and
play a role in dissolving otherwise insoluble metals from
precipitates or crystalline lattices.
Of somewhat more importance in terms of complex stability
are the multidentate organic ligands. One of the reasons for
121
-------
TABLE 53. PERCENTAGES OF THE TOTAL AMOUNTS OF
IRON, NICKEL, COBALT, CHROMIUM, COPPER, AND MANGANESE
TRANSPORTED BY FIVE MECHANISMS IN THE
YUKON AND AMAZON RIVERS (246)
Mechanism
In solution and
organic complexes
Adsorbed
Precipitated and
copreci pita ted
In organic solids
In crystalline
sediments
In solution and
organic complexes
Adsorbed
Precipitated and
copreci pi tated
In organic solids
Iron Nickel
Amazon River
0.7 2.7
0.02 2.7
47.2 44.1
6.5 12.7
45.5 37.7
Yukon River
0.05 2.2
0.01 3.1
40.6 47.8
11.0 16.0
Cobalt Chromium
1.6 10.4
8.0 3.5
27.3 2.9
19.3 7.6
43.9 75.6
1.7 12.6
4.7 2.3
29.2 7.2
12.9 13.2
Copper Manganese
6.9 17.3
4.9 0.7
8.1 50
5.8 4.7
74.3 27.2
3.3 10.1
2.3 0.5
3.8 45.7
3.3 6.6
In crystalline
sediments 48.2 31.0 51.4 64.5 87.3 37.1
122
-------
TABLE 54 . HEAVY METAL DISTRIBUTION
IN STREAMS (512)
CO
Percentage of element occurring in dissolved and
solids
Cadmium
Cobalt
Copper
Iron
Manganese
Nickel
Dissolved solid
Coarse parti cul ate
Colloid
Dissolved solid
Coarse participate
Colloid
Dissolved solid
Coarse parti cul ate
Colloid
Dissolved solid
Coarse parti cul ate
Colloid
Dissolved solid
Coarse particulate
Colloid
Dissolved solid
Coarse particulate
Colloid
Sample 1
95.4
3.9
0.8
95.9
3.9
0.2
95.0
3.6
1.4
18.8
79.5
1.7
23.2
76.4
'0.4
96.5
3.4
0,2
Sample 2
95.3
4.2
0.5
93.2
6.2
0.6
94.4
3.8
1.8
12.5
86.0
1.4
41.7
57.6
0.7
95.2
4.5
0.3
particulate
Sample 3
95.8
3.5
0.7
95.9
3.5
0.7
90.4
8.2
1.4
26.9
67.1
6.0
18.5
74.8
6.7
96.6
2.4
1.0
Sample 4
85.1
8.9
6.0
82.3
17.5
0.2
93.0
5.8
1.2
20.4
75.5
4.1
10.4
89.5
0.1
84.7
14.8
0..5
-------
TABLE 54 (continued)
Percentage of element occurring 1n
solids
Lead
Zinc
Dissolved solid
Coarse particulate
Colloid
Dissolved solid
Coarse particulate
Colloid
Sample 1
95.0
5.0
Tr
85.0
15.0
Tr
dissolved and particulate
Sample 2
90.9
7.6
1,6
53,3
46.2
0.5
Sample 3
87.9
9.3
2.9
91,9
7.3
0.9
Sample 4
89.5
10,1
0.4
81.1
18.5
0.4
ro
-------
TABLE 55. METALS COORDINATED BY LI6ANDS NORMALLY
FOUND IN NATURAL HATERS (521 )
ro
en
Metal
Carried
Boron
Aluminum
Barium
Chromium
Copper
Cobalt
Molybdenum
Manganese
Iron
Nickel
Z1nc
Cadmium
Mercury
Lead
Arsenic
Antimony
Ugands Responsible
0~* S"2 , , ?
H20 or OH" or SH" S04"Z S03'Z F~ Cl" C03~* Organic NH3 NHgOH N02
26 1461 6
5 P p(c)
2 64 6 c) 6 6
3 6 4(b) 6(c) 6 (e) 6
46 4 6(c) 6 6
16 6 v
3 4 6 c 6
3 6 614 6 c 6(d)
3 ? 4 6 c 6 (e)
3 6 6 4 6 c) 6 (e)
4 46 616
4(a) 6 6 1 6
2 P 4 6(c) 6
1 6 4
1 6 4
Footnotes
1 In normal natural waters (pH 0-11) this metal Is coordinated by this llgand.
2 Here coordination occurs only at pH of less than about } . .
3 Normally coordination only occurs at a pH of ess than 4, but If the pCO, Is low
(high concentration), then bicarbonate which 1s water coordinated will bfe formed.
4 Coordination occurs at a pH of 7 or less.
-------
5 The solubility falls markedly in the presence of this
ligand at above pH due to precipitation of a carbonate
or similar basic compound.
6 Coordination occurs only at pH above 7 due to ligand
instability, etc. 3
7 Coordination occurs only at pH above 8-9.
P Precipitation almost always occurs.
(a) Water will only coordinate if no other stronger
ligand is present. In some cases, there is an
equilibrium.
(b) Bromide and iodide resemble chloride except that
they both precipitate silver, whereas silver
chloride is fairly soluble due to AgClz'ions at
high chloride concentrations. Iodide also pre-
cipitates copper and gold.
(c) Bicarbonate usually forms carbonato complexes, but
metals so marked have a soluble bicarbonate which
is water coordinated. Be and Tl have soluble water
coordinated carbonates, and Ag has both sparingly
soluble water coordinated carbonate and hydroxide.
Two valent iron in absence of air only.
If ammonia is absent, a complex may be formed.
If nothing is marked, there is no coordination of this
metal by this ligand in natural waters.
(d)
(e)
-------
the lack of inorganic complex stability is that most of the
inorganic ligands are monodentate, i.e., there is one ligand for
each metal ion coordination site. Organic ligands are multi-
dentate, i.e., a given ligand can usually bond to two or more
of a given ion's coordination sites. A multidentate complex
(chelate) is more stable than a corresponding complex with
monodentate ligands; thus, a chelate complex is apt to keep a
metal ion in solution far longer than will an inorganic complex.
Normally, this is not a problem; in relatively unpolluted fresh
water the organic content is low, but in highly polluted water
unusually high soluble metal concentrations may result. Further-
more, there is evidence that some synthetic organic ligands,
such as may be found in wastewater, form stronger complexes than
do natural organic ligands (384). It has been demonstrated that
one synthetic ligand, nitrilotriacetate (a proposed substitute
for phosphates in detergents), is capable of dissolving signifi-
cant quantities of precipitated lead out of bottom sediments
(268, 715 ).
The tendency for a given metal ion and ligand to form
complexes depends on solution pH, concentration of the metal
and ligand, concentrations of other metals and ligands in
solution, equilibrium constants, redox conditions, and so forth.
No two elemental contaminants behave exactly alike, and even
different oxidation states of the same element may exhibit
widely varying solution chemistry. Moreover, natural water
systems are seldom in an ;equilibrium condition before, much less
after, wastewater addition. This constantly changing system
makes concise pathways almost impossible to construct. In
general, low pH, an oxidizing environment, and the presence of
a variety of ligands enhance element solution tendencies.
This is significant from a public health standpoint, because
soluble elemental species are much more readily available for
human contact than are precipitates or particulate elementals.
Elemental/inorganic particulate interactions typically
account for the bulk of the nondissolved elemental fraction.
These interactions include coulombic or ionic attraction,
precipitated or coprecipitated coating, or lattice incorporation.
Coulombic attraction, or adsorption, is the least important
transport mechanism except in the case of colloidal particulates,
such as microparticulate iron or manganese hydroxides, which
carry a weak negative charge and attract elemental cations.
Larger particulates do not possess a strong enough charge to
make coulombic attraction important.
Ionic attraction, or ion exchange, is somewhat more
important. In this process, the heavy metal elements (Mn,
Fe, Co, Ni, Cu, Zn, Mo, Cd, etc.) replace alkali and alkali
earth cations (K, Na, Li, Mg, Ca) attached to crystalline
lattices by ionic bonds. These ionic bonds will hold unless
(1) the element is displaced by another element forming a
127
-------
stronger ionic bond, (2) a ligand forming a coordination bond
stronger than the ionic bond breaks the ionic bond, or (3) an
excess of alkali or alkali earth cations is available to force
the equilibrium back to its original state.
According to Gibbs (246), lattice incorporation is generally
insignificant as a transport or removal mechanism of dissolved
wastewater elements. It is a slow process that takes place
in the sediments and has a more significant impact on the
elemental composition of the sediments. The lattice-incorporated
element burden of a water system is primarily from weathered
rock, sand, and clay.
Precipitated and coprecipitated metal coatings account for
most of the non-native particulate element content of a water
system. Under favorable pH-EH conditions, metal precipitates
will form. The initially small precipitate particles will tend
to agglomerate or adhere to any available surface. In addition,
cations held to particulates by coulombic or ionic bonds can
form covalent bonds with anionic components of the particulate,
if solution redox potentials change. In either case, the
particulates are left with a coating of metal precipitates.
This coating ultimately settles out of solution with the partic-
ulate, removing the elements from possible ready human
contact unless they are redissolved by a change in redox
conditions, a strong ligand, or some other agent strong enough
to attach the precipitate. These coatings may account for the
bulk of the inorganic particulate element burden of waste-
waters.
Elemental contaminants incorporated with biological particu-
lates constitute the remainder of the particulate elemental
burden of a water body or wastewater. This incorporation may
take the form of surface adsorption, inorganic particulate
ingestion, or biochemical incorporation into an organism's
tissues. Obviously, the role played by biological transport is
highly dependent on the type and quantity of organisms present.
Surface adsorption is usually associated with microorganisms.
Particulate ingestion is associated with those organisms that
have internal digestive organs (e.g., fish, crustaceans, worms,
etc.); ingested particulates are usually eliminated within a
short time, but the elements associated with them may be
biochemically incorporated into the organism's tissues. From a
public health standpoint, soluble and biochemically incorporated
elementals are the most important, for it is by these routes
that potentially hazardous elements reach man. Biochemical
incorporation involves both essential trace element concentra-
tion (e.g., cobalt in vitamin B-12) and reaction of an element
with cellular chemicals (e.g., the reaction of mercury with
sulfur-containing amino acids in proteins). Both plants and
animals are involved and, thus, the concentration of a given
element may move up the food chain. The incorporation is
128
-------
reversible; once the organism is removed from contact with the
element, the latter can gradually be excreted.
No two elements behave exactly alike; furthermore, the
number of factors available that can affect transport mechanisms
makes the possibilities nearly endless. There are similarities,
however, that make the use of examples illustrative and useful;
mercury, arsenic, iron, cadmium, copper, and lead will be used
to provide detailed descriptions of the general pathways dis-
cussed above.
Mercury from wastewater enters a water system primarily as
the metal or divalent cation. Although of limited solubility,
it can reach concentrations of 100 ppb in aerated water (234;.
Metallic mercury alone is soluble up to 25 ppb and will hydrolize
to soluble Hg (OH)2 in oxygenated systems, increasing the overall
solubility and water content. Despite these solubility figures,
mercury concentrations seldom exceed 5 ppb (Table 56 ) except
in polluted water.
Inorganic and biological adsorption, absorption, and pre-
cipitation serve to keep the concentrations of dissolved mercury
much lower than the theoretical maximum. In general, the bulk
of the mercury in a given water system is in the sediments;
Table 57 gives a summary of some of the mercury concentrations
in the sediments of Lake Erie. In reducing sediments, mercury
is tied up as the sulfide, although if the system becomes
sufficiently alkaline, HgS?" may be released into solution.
Should the sediments become aerobic, the sulfide will be oxidized
to sulfate, and the mercury will be released.
All soluble mercury species except mercuric sulfide can be
absorbed by bacteria. Once the mercury is in the bacteria, a
series of transformations - possibly via a detoxification
mechanism - convert the incorporated mercury into mono- and
dimethyl mercury, both soluble at low concentrations and readily
released into solution. The methyl mercury compounds are much
more 1ipid-preferring than the inorganic forms and are quickly
absorbed by living tissues. As a rule, mercury concentrations
tend to increase in organisms up the food chain, so that the
highest concentrations are found in fish. This is partly due to
absorption of methyl mercury from the water and partly from
inqestion of plants or smaller organisms containing methyl
mercury. When the organisms die, the mercury returns to the
sediments, where most of the bacterial methylation occurs.
Table 57 lists some sample sediment and plankton/algae mercury
concentrations in Lake Erie.
Arsenic, selenium, and antimony are chemically similar and
exhibit analogous environmental behavior. Arsenic has been
studied far more than either selenium or antimony. The following
129
-------
TABLE 56. SELECTED CONCENTRATIONS OF
MERCURY IN NATURAL WATERS (234)
Source and Location
Mercury (ppb)
River water, European USSR
River water, Armenia
Saale River, Germany
River water, Italy
River water, near mercury deposits, Italy
Colorado River, Arizona
Ohio River, Illinois
Mississippi River, Kentucky
Missouri River, Montana
Missouri River, St. Louis, Missouri
Kansas River, Topeka, Kansas
Hudson River, New York
Lake Champlain, New York
Maumee River, Antwerp, Ohio
Delaware River, New York
0.4-2.8
1-3
0.035-0.145
0.01-0.05
up to 136
<0.1
0.1
2.8
3.5
0.1
0.1
6.0
130
-------
TABLE 57. MERCURY CONTENT OF SEDIMENTS AND PLANKTON/ALGAE SAMPLES
COLLECTED FROM LAKE ERIE (519)
Mercury content in vg/ga
Station
No.
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
Approximate
Location
Buffalo River
Cattaraugus Creek
Barcelona
Ashtabula
Fairport
Cleveland
Toledo
Detroit River
Mid. Bass Island
Port Crewe
Port Stanley
Long Point
Long Point Bay
Port Maitland
Mid-Lake
Black Rock Channel
ij *> "- - . -l"!J|_-' ___ '-!__ '"!_ I 1" I"" i " '-'-'.' ^
Sediments
2.0
1.2
0.6
4.6
1.5
12.0
10.4
4.5
1.5
0.5
1.5
7.0
1.0
1.8
1.5
12.4
..I _!! _! I_M _!>-
Plankton/Algae
31.2
25.1
2.8
7.4
12.8
33.5
20.5
26 .1
20.1
12.4
12.0
14.7
23.7
15.4
0.6
27.8
±aaam^aamam
a In terms of the equivalentdry wt of the sample.
b Sediment samples from 3 to 30 cm below the water-sediment interface.
131
-------
discussion of arsenic is largely applicable to selenium and
antimony as well.
Arsenic has an unusually complex chemistry in aquatic
systems: oxidation-reduction, ligand exchange, precipitation,
adsorption, and biomethylation reactions all take place.
Arsenic species can be removed from water via surface adsorption
"^
and coprecipi tation with metal ions; both arsenate (AsO^") and
arsenite (As03~3) have a high affinity for hydrous iron oxides
and readily coprecipitate with or adsorb onto them. Signifi-
cantly, iron ores are always enriched with arsenic (214).
Aluminum hydroxide and clays are adsorb arsenate species,
although to a lesser degree.
Microbial transformations of arsenic, while demonstrable
in the laboratory, have not been positively identified in
natural water systems. The two most commonly postulated trans-
formations are oxidation of arsenite and methylation. Methyla-
tion is important because it could be a means by which sediment
arsenic is recycled back into the water system; natural aquatic
methylation has not been demonstrated.
Soluble iron entering a water system in wastewater will
usually be either ferrous (Fe II) or complexed ferric (Fe III)
iron. The former is much more soluble than the latter (which
has a stronger tendency to form complexes), although neither
tends to remain in solution long. In the surface layers of
most natural waters, pH levels and oxygen conditions are such
that Fe (II) is readily oxidized to Fe (III), which just as
readily hydrolyzes to insoluble hydrous ferric oxide (FeOOH).
Hydroxide has a much stronger affinity for ferric iron than do
basic organic or inorganic ligands.
Hydrous ferric oxide tends to form microcrystal 1 ine preci-
pitates of a colloidal nature, so that it is almost impossible
to analytically distinguish between soluble and colloidal iron.
Consequently, the two forms of iron are usually reported together
as soluble iron. Although hydroxide supersedes other anionic
ligands, frequent incorporation of coordinating anions into
ferric oxide precipitates enhances colloidal stability and
further blurs the distinction between the colloid and soluble
ferric complexes.
Cadmium readily precipitates as the hydroxide or carbonate
and consequently is not normally found in high concentrations
in surface waters. In fact, several researchers (188, 461 ) have
noted that high soluble cadmium concentrations are invariably
associated with polluted water that receives a steady cadmium
source, such as industrial wastewater.
132
-------
Cadmium (II) readily hydrolyzes and forms transitory
inorganic complexes, such as chloride complexes that have a
limited affinity for hydrous iron and manganese oxides, and
organic particulates. The organic affinity probably indicates
a reaction between the cadmium and sulfur-containing compounds.
Cadmium forms the insoluble hydroxide at pH levels of 7
and above; it forms the insoluble carbonate under oxidizing
conditions, particularly in soft waters where cadmium does no.t
have to compete with calcium and magnesium for the carbonate
anion. Once cadmium has precipitated and settled into the
sediments, it is not readily removed. Consequently, if cadmium
additions are reduced, a water body will tend to purify itself
of soluble cadmium.
Copper, and to a lesser extent nickel, occupy an unusual
position in water chemistry and biology because they are both
nutrients and toxins. This has a pronounced effect on their
water chemistry. Copper contained in wastewater may be either
soluble or particulate; neither form predominates as a rule.
Copper adsorbs readily onto clay and organic particulates.
Copper also forms several very stable complexes. In pure water,
while the aquo complex may predominate, the carbonate, chloride,
and amine inorganic complexes are much more stable.
Ultimately, the soluble stability of copper can be
attributed to organic complexes, since copper forms coordination
complexes with virtually every conceivable organic ligand.
These complexes are very stable thermodynamically and are also
resistant to microbial attack, a mechanism responsible for the
destruction of most organic complexes. Copper is a bacterial
toxin and, if released from its complex by microbial attack,
simply kills the offending bacteria and forms a new complex (461)
Copper is removed from solution via precipitation or
biological incorporation. Since the most common precipitate is
the carbonate, most sediment copper is in the carbonate form
(140, 461). An essential trace nutrient, copper is readily
incorporated into aquatic plants and animals.
The main soluble species of lead in wastewater are the
lead (II) cation and the hydrolyzed complex Pb (OH)3~. Lead
forms a variety of stable complexes as well; researchers (381)
have identified both PbOH+ and Pb(C03)2"^ in natural water
systems. Lead complexes easily with a variety of organic
chelates, forming very stable complexes. Some of these com-
plexes are more stable than the sediment lead precipitates;
therefore, they will actually dissolve otherwise insoluble lead.
A case in point is nitrilotriacetate, which can solubilize lead
from lead carbonate precipitates (268).
133
-------
Low water organic content generally prevents solution lead
concentrations from exceeding a few parts per billion. In most
water systems, lead introduced with wastewater readily forms
insoluble Pb(OH)2 and PbC03, which will precipitate and adsorb
onto suspended particulates. Ionic lead is not so strongly
adsorbed, although it does have some affinity for clays.
Hydrous iron oxides strongly sorb ionic lead at neutral
to slightly acidic pH levels. Some ionic or complexed lead
adsorbs onto or is chelated with the surface mucilage of algae,
and microorganisms immobilize substantial quantities of inorganic
lead, presumably on or in all membranes (648 ). As a result of
all of these mechanisms, most of the water lead burden is
associated with particulate matter, and most of the lead entering
a normal water system ultimately finds its way into the sediment!
Natural water bodies normally contain very low dissolved
concentrations of the more harmful elemental contaminants.
Unless wastewater additions are voluminous and repeated, natural
water chemistry can purify the water of soluble species fairly
well. However, there is a buildup of these elements in the
sediments. This means that if the local water chemistry should
change significantly, the elements can still be released to
solution. Natural water purification mechanisms can only change
the wastewater element problem from a real to a potential
hazard; they cannot solve the problem of element contamination.
BIOCIDAL CONTAMINANTS
In general, municipal wastewater will have detectable
quantities of biocides only if it contains biocide manufacturing
wastes. The single most important source of biocidal contami-
nants in fresh-water bodies is surface runoff, followed by aerial
fallout and industrial waste discharge from plants manufacturing
biocides. Cleanup and disposal by households, farmers, gardeners,
etc., contribute minimally to the overall wastewater burden.
In this discussion, biocides will be classed as chlorinated
hydrocarbons, organophosphates, carbamates, and ionic biocides
(Table 58).
Biocides can be transported or removed from the system by
microbial or chemical degradation, photodegradation, adsorption
to sediment or humic matter, adsorption, volatilization, and
biological uptake. All of these mechanisms are in turn affected
by pH, temperature, salt or organic content, and bioproductivity
One mechanism that has not been studied to any great degree -
especially in fresh water - is aerosolization. This mechanism
will be discussed in greater detail in the marine water section
of this chapter, as its importance in fresh-water systems is
limited mainly to the larger lakes. Briefly, however, aerosoli-
zation occurs through the action of wind and waves on floatables.
134
-------
TABLE 58. BIOCIDE TYPES AND EXAMPLES
Chlorinated Hydrocarbons
DDT (ODD, DDE)
Methoxychlor
E n d r i n
D i e 1 d r i n
Aldri n
Toxaphene
Lindane
Chlordane
Heptachlor
Organophosphates
Parathion
Malathion
Dimethoate
Methyl parathion
Phorate
Demeton
Ethion
Disulfaton
Carbamates
Carbaryl
Sevin
Baygon
Pyrolan
Dimetilan
Ionic Biocides
Diquat
Paraquat
Chlormequat
Morfaunquat
Phosphon
Hyamine
2,4-D
2,4,5-T
Dalapon
Si 1 vex
Dichlobenil
135
-------
Aerosols and particulates can be released to the air and trans-
ported great distances by the wind; biocides can concentrate in
floatables via dissolution in surface oil, adsorption on floating
matter, or flotation (caused by low specific gravity and insolu-
bility), thus becoming amenable to the aerosolization process.
As mentioned above, this is not an important transport mechanism
in most fresh-water systems.
Various transport mechanisms affect the biocide classes
differently. This is demonstrated in Table 59, which compares
the persistence of selected chlorinated hydrocarbons, organo-
phosphates, and carbamates in river water. Because of these
differences, the biocide classes will be discussed separately.
The chlorinated hydrocarbon pesticides are all insoluble
in water, with the exception of lindane, which is sparingly
soluble to 10 ppm (211). They are generally resistant to
microbial and chemical degradation, as evidenced by their
estimated environmental half-lives, shown in Table 60.
TABLE 60. ESTIMATED PESTICIDE HALF-LIVES (211)
Pesticide Half-Life, yrs
Lindane 2
Chlordane 8
Toxaphene 11
Heptachlor 2 to 4
DDT 10 to 20
Endrin (Dieldrin) 8 to 10
These pesticides are somewhat more susceptible to photo-
degradation, although the degradation products are often as
toxic as the parent compound, regardless of the type of
degradation. DDT is decomposed chemically to ODD and DDE and
photochemically to PCB's (162, 550 ); aldrin is photooxidized
to the more toxic dieldrin (162); and methoxychlor is degraded
to methoxychlor DDE (501 ). Surface oil slicks tend to concen-
trate chlorinated hydrocarbons and thus make them more available
for photochemical degradation (162).
Chlorinated hydrocarbons in general readily adsorb onto
fungi, algae, and floe-forming bacteria (385, 501 ), and thus
tend to concentrate in biological communities. When ingested
by higher organisms, they accumulate in lipid tissues; conse-
quently, there is a tendency for chlorinated hydrocarbons to
concentrate up the food chain.
Chlorinated hydrocarbon insecticides differ in chemical
structure, but they all exhibit affinity for organic sediments
136
-------
TABLE 59. PERSISTENCE OF COMPOUNDS IN RIVER WATER (415)
Original compound found, percent
Compound 0-time 1 wk 2 wk 4 wk 8 wk
Organochlorine compounds
BHC 100 TOO 100 100 100
Heptachlor 100 25 0 0 0
Adlrin 100 100 80 40 20
Heptachlor epoxide 100 100 100 100 100
Telodrin 100 25 10 0 0
Endosulfan 100 30 5 0 0
Dieldrin 100 100 100 100 100
DDE 100 100 100 100 100
DDT 100 100 100 100 100
ODD 100 100 100 100 100
Chlordane (tech.) 100 90 85 85 85
Endrin 100 100 100 100 100
Organophosphorus compounds
Parathion 100 50 30 <5 0
Methyl parathion 80 25 10 0 0
Malathion 100 25 10 0 0
Ethion 100 90 75 50 50
Trithion 90 25 10 0 0
Fenthion 100 50 10 0 0
Dimethoate 100 100 85 75 50
Merphos 00000
Merphos recov. as Def 100 50 30 10 <5
Azodrin 100 100 100 100 100
Carbamate compounds
Sevin 90 5 0 0 0
Zectran 100 15 0 0 0
Matacil 100 60 10 0 0
Mesurol 90 0 0 0 0
Baygon 100 50 30 10 5
Monuron 80 40 30 20 0
Fenuron 80 60 20 0 0
137
-------
and resistance to microbial attack. As a result, there is
accumulation in bottom sediment. Research on Lake Michigan
demonstrates this, as shown in Table 61. Routh ( 558) showed
that DDT, with its affinity for fine participate clay sediments,
concentrated up to 20 times normal background levels, from 10
to 200 ppb. This affinity for organic matter and particulates
leads to high sediment DDT concentrations. Table 62 shows DDT
concentrations in stream sediments over a period of time.
Adsorption of DDT on algae can be 10 to 100 times greater than
adsorption on clay (350). Moreover, DDT seems to have an
inhibitory effect on sediment bacteria (11).
There has been little research on other chlorinated hydro-
carbons, much of it limited to an evaluation of environmental
levels. Table 63 gives the results of one such survey for
d i e 1 d r i n .
TABLE 63. DIELDRIN IN RIVER BOTTOM SILTS (466)
Source D i e 1 d r i n (ppb)
Iowa River 8.8
Des Moines River 35
East Nishnabotna River 21
West Nishnabotna River 16
Upper Iowa River <1
Johnson County Creek 170
Other researchers have found that the highest reported
concentrations of several pesticides in major U.S. river basins
from 1958 to 1965 were as follows: dieldrin, 0.100 yg/£; endrin,
0.116 yg/£; and DDT, 0.148 yg/£. Dieldrin was the most widely
found pesticide (679 ).
The organophosphorus biocides are more soluble than the
chlorinated hydrocarbons. These solubilities range from 1 ppm
for ethion to 20,000 ppm for dimethoate; most fall in the 25 to
150 ppm range (211). The organophosphorus biocides are also
more amenable to both microbial and chemical degradation. Even
parathion, the most chemically resistant of the organophosphates,
will degrade via ester linkage hydrolysis in a few months under
normal conditions. The degradation takes place in just a few
weeks in polluted water with a high bacteria count (264). Yu
and Sanborn's (709 ) experimental evaluation of parathion in a
model ecosystem yielded a calculated half-life of 15 to 16 days.
In a similar study, guthion yielded a half-life of one month at
pH levels less than 9 and a half-life of less than one week at
more alkali ne pH's.
138
-------
CO
TABLE 61 . CHLORINATED HYDROCARBON INSECTICIDES
IN SOUTHERN LAKE MICHIGAN SEDIMENTS (yg/1) (382)
Insecticide
p,p'-DDT
o,p-DDT
p,p'-DDE
o,p-DDE
p,p'-DDD
o,p-DDD
Total DDT
complex
Dieldrin
Heptachlor
epoxide
Lindane
Mpdian
9.3
1.2
2.2
Tr
3.0
Tr
18.5
2.0
Tr
Tr
interval
50%
Mid-range
5.5-17
Tr-2.0
0.6-3.5
Tr
1.4-10
Tr-1.8
10-32
1.3-4.1
Tr-0.7
Tr
No. of
Samples
59
54
59
49
54
49
59
54
54
45
i
Median
3.8
0.7
0.8
ND
0.5
ND
6.3
Tr
Tr
ND
2-6 cm
50%
Mid-range
2.6-5.2
Tr-1.0
Tr-1.5
ND
Tr-2.0
ND-0.5
3.9-13
Tr-1.1
ND-0.5
ND-Tr
No. of
Samples
40
37
40
32
37
32
40
37
32
30
Median
3.0
Tr
0.6
ND
ND
ND
3.4
Tr
ND
ND
6-12 cm
~~%Q%
Mid-range
1.5-6.0
ND-2.3
Tr-2.1
ND-Tr
ND
ND
2.2-8.1
Tr-0.9
ND
ND
No. of
Samples
20
14
19
12
12
12
20
14
14
-------
TABLE 62. DDT CONCENTRATIONS IN STREAM SEDIMENTS (271)
Years after DDT
one (ppro)
application
0 .83
(.04-1.6)
1 1 .08
(.25-1.9)
2
3 .21
(.12-.30)
4 .21
(.16-.25)
5 .59
(.07-1.9)
6 .06
7 .21
(.11-.31)
8 .13
9 .03
(.02-.04)
10 .07
(0-.16)
Never sprayed .006
(0-.02)
Two sprays .43
(.17-.77)
Three sprays .35
(.17-.6)
140
-------
Interestingly, the degradation of organophosphates can be
inhibited by the presence of other synthetic organic chemicals.
Experiments were conducted with two detergent surfactants -
alkyl benzene sulfonate (ABS) and linear alkyl benzene sulfonate
(LAS). These experiments demonstrated increased persistence
for several organophosphate insecticides, especially parathion
and diazinon (162). As a result, highly polluted water may
exhibit accumulations or half-lives far beyond the normal for
organophosphates, which, as a rule, neither persist nor accumu-
late in the environment, but are removed entirely within a few
months.
Carbamate biocides are moderately soluble, ranging from 7
ppm for terbutol to 250ppm for propham and averaging around 100
ppm (211). In general, they decompose easily and show little
tendency toward adsorption on suspended material, but hydrolyze
readily. The hydrolysis is particularly pH dependent, virtually
ceasing entirely below pH 5 (211) and increasing as the pH and
temperature rise. High salt content affects the hydrolysis
rate inversely, slowing the rate as the salt concentration
increases (211). Carbamates photodecompose readily - increasingly
so, as the pH rises - and can be rapidly biodegraded under
normal circumstances (550 }. Carbamates are not, then, persistent
in normal water systems, lasting only a few days to a few weeks,
but remain as a stable compound in acidic waters (211).
Ionic biocides are a broad class embracing a variety of
chemical types and uses. They are all considered soluble in
water, with solubilities ranging from 100 to more than 1,000,000
ppm. Ionic biocides that are marginally soluble in pure water
have increased solubilities in natural waters high in humic
acid salts (211). With few exceptions, these biocides do not
accumulate or persist and, consequently, are seldom found in
high concentrations.
Ionic biocides are, however, strongly adsorbed onto soil
particles, all types of clay, humic matter, and organisms - in
short, onto anything with a partial charge or an ion exchange
capability (211). They are generally resistant to chemical
attack but photodegrade readily, except when adsorbed onto
particulate matter (211). Ionic biocides respond differently to
microbial attack, but are absorbed by many organisms. As a
result, they tend to concentrate in organisms and up the food
chain. Research on TCDD, an ionic herbicide residue, demon-
strated that accumulation was directly related to water concen-
trations (0.05 to 1,330 ppb) and averaged between 400,000 and
2,000,000 times the water concentration (321).
SYNTHETIC/ORGANIC CONTAMINANTS
Recently, there has been a great interest in identifying
synthetic/organic trace compounds in water supplies drawn from
141
-------
rivers and in other water bodies receiving treated wastewater.
Although studies have been made of the concentrations found in
various water systems, neither the environmental pathways nor
the potential health effects to man of these substances have
been studied to any great extent.
Over 100 synthetic/organic compounds have been identified
in various drinking water sources. Thirty-six compounds were
found in the lower Tennessee River (Table 64), while 66 were
identified and quantified in Mississippi River water at New
Orleans (Table 65 ). Table 66 lists the results of organic
analyses of several other domestic water supply sources.
The many different types of compounds under discussion here
make generalizations difficult regarding their environmental
fate. For instance, acetone is infinitely soluble in water;
chloroform is soluble to about 8,200 mg/£; carbon tetrachloride
is soluble to about 800 mg/l; and n-decane is insoluble. The
specific gravity of toluene is less than that of water, while
the specific gravity of carbon disulfide is greater. Acetalde-
hyde is readily metabolized since it is a natural metabolic
intermediate, but branched alkyls are almost impervious to
microbial attack.
The differences in man-made synthetic/organic compounds
exceed the similarities, but in general, these compounds are
persistent and resist microbial degradation. Beyond that
generalization, research has been too limited to discuss
specific compounds in detail.
Polychlorinated biphenyls (PCB's) are the only class of
synthetic/organic contaminants that have been studied in detail.
They are virtually insoluble in water, which, combined with a
high specific gravity and volatility, serves to keep solution
PCB concentrations low. However, PCB's are strongly adsorbed
onto suspended particulate matter and transported through the
water system. Because of their heavy, insoluble character and
sediment affinity, they tend to accumulate in bottom sediments.
A comparison of selected water and sediment PCB concentrations
from across the United States is presented in Table 67.
PCB's are fairly stable in fresh-water systems, resisting
hydrolysis and chemical degradation, and are not amenable to
photodegradation (481). Theoretically, they should readily
vaporize from solutions, but this is prevented by their tendency
to sink or strongly adsorb onto suspended matter. Only PCB's
that are associated with floatables or oil slicks appear to
vaporize to any great degree. The lower isomers (four or fewer
chlorine atoms) are somewhat responsive to biodegradation, but
the degradation products are frequently more toxic than the PCB
itself (481). The higher isomers resist microbial attack.
142
-------
TABLE 64
ORGANIC COMPOUNDS IDENTIFIED TO DATE
FROM LOWER TENNESSEE (615)
Acenaphthene
Allylbenzoate
Anthracene
Benzene
Biphenyl
Butyl benzene
5-Chloro-2-Methyl benzofuran
p-Cresol
Diallyl Adipate
Dibutyl Phthalate
Di phenylacetylene
COMPOUNDS ----------
Fluorene
Hexachlorobenzene
Indene
o-Methoxybenzoic Acid
2-Methylanthracene
2-Methylbiphenyl
4-Methyldiphenylacetylene
Methyl Indene (2 isomers)
1-Methylnaphthalene
Naphtha!ene
p-Nonylphenol
n-Octyl-o-Phthalate
1,1-Diphenylethene
2,6-Di-Tert-Butyl-4-Methylphenol Pyrene
Ethylbenzene Styrene
Ethyl o-Phthalate 1,2-Tetradecanediol
Ethylstyrene Toluene
Ethylene Dimethylacrylate 3,4,4-Trimethyl-2-Hexene
Fluoranthene Xylene
143
-------
TABLE 65
ORGANIC COMPOUND IDENTIFICATIONS
NEW ORLEANS AREA WATER SUPPLY STUDY
(615)
Highest Measured Concentration
vfl/1
Compound
1
^
3
4
5
6
7
8
9
10
Acetaldehyde
Acetone
Alkylbenzene-Cg fsorcer
Alkylbenzene-Cg isomer
Alkylbenzene-C2 isomer
Alkylbenzene-C3 isomer
Alkylbenzene-C3 isomer
Alkylbenzene-C3 isomer
Atrazine *
(2-chloro-4-ethylamino-
6-isopropylamino-
v-triazina)
Deethylatrazine
(2-chloro-4-amino-
6-isopropylamino-
^.-triazinc)
Carroll ton
Water Plant
D-VOA
D-VOA
0.05
0.33
0.11
0.01
0.04
0.02
5.0
0.51
Jefferson # 1
Water Plant
NE
NE
NO
ND
0.03
NO
0.05
NO
4.7
0.27
Jefferson ? 2
Water Plant
NE
NE
ND
NO
NO
ND
0.02
ND
5.1
0.27
144
-------
TABLE 65 (continued)
Highest Measured Concentration
Compound
11
12
13
14
15
16
17
18
19
20
21
Benzyl butyl phthalate*
Bromod i chl oroethane
Bromoform *
Butanone
Carbon disulfide
Carbon tetrachloride
bis-2-Chloroethyl ether*
Chloroform *>a
bis-2-Chl oroi sopropyl
ether *
n-Decane *
Decane-branched isomer
Carrol. Hon
Water Plant
0.64
0-VOA
0.57
D-VOA
D-.VOA
D-VOA
0.07
173
0.18
0.04
0.03
Jefferson # 1
Water Plant
0.81
HE
ND
NE
HE
NE
0.16
NE
0.05
NO
ND
Jefferson f 2
Water Plant
0.73
NE
ND
NE
NE
NE
0.12
NE
0.03
ND
NO
145
-------
TABLE 65 (continued)
Highest-Measured Concentration
t-g/i
Compound
22
23
24
25
26
27
28
29
30
31
32
Di broraod i chl oroethane
isoiner
Oibromochlorome thane *
Dibutyl phthalate *
2,6-Di-t-butyl-£-
benzoqulnone *
Oichlorobenzene isomer
1,2-01 chl oroethane a
Oichloromethane
Dieldrin **
Diethyl phthalate *
Di(2-ethy1hexy1) phthalate "
Dihexyl phthalate
Carroll ton
Mater Plant
0.33
1.1
0.10
0.22
0.01
8
D-VOA
0.05
0.03
0.10
0.03
Jefferson 9 1
Water Plant
NO
0.30
0.16
0.19
D-RE
NE
NE
0.07
0.03
0.31
ND
Jefferson 1 2
Water Plant
0.63
0.60
0.19
0.23
ND
NE
NE
0.05
0.01
0.06
ND
146
-------
TABLE 65 (continued)
Highest Measured Concentration
ug/i
Compound
33
34
35
36
37
38
39
40
41
42
43
Dihydrocarvone
Diisobutyl phthalate *
Dimethyl phthalate
Dioctyl adipate
Dipropyl phthalate *
n-Dodecane *
Endrin **
Ethanol
o.-Ethyl toluene *
£-Ethyl toluene *
1, 2, 3, 4, 5, 7, 7-
Heptachloronorbornene *
Carroll ton
Water Plant
0.14
0.59
0.27
0.10
0.07
0.01
0.004
D-VOA
NO
0.02
0.06
Jefferson 3 1
Water Plant
0.06
ND
O.IS
ND
0.13
ND
NYE
NE
0.04
0.03
0.05
Jefferson § 2
Water Plant
0.07
ND
0.18
ND
0.14
ND
NYE
NE
0.02
0.03
0.05
147
-------
TABLE 65 (continued)
Highest Measured Concentration
Compound
44
45
46
47
48
49
50
51
52
53
54
Heptachloronorbornene
isomer
Hexachloro-1 ,3-butadiene *
Hexachloroethane *
Isophorone *
Limonene *
Kethanol
Methyl faenzoate
3-Methylbutanal
2-Methylpropanal
n-Konane *
n-Pentadecane *
Carroll ton
Water Plan
0.06
0.16
4.4
1.5
0.03
D-VOA
NO
D-VOA
D-VOA
0.03
0.02
Jefferson # 1
Water Plant
0.04
0.27
0.19
2.2
KD
NE
D-RE
NE
NE
ND
ND
Jefferson # 2
Water Plant
0.04
0.21
0.16
2.9
ND
NE
NO
NE
NE
ND
ND
148
-------
TABLE 65 (continued)
Highest Measured Concentration
pg/i
55
56
57
58
59
60
61
62
63
64
65
66
Compound
Tetrachloroethane
Isomer
Tetrachloroethylene
n-Tetradecane *
Toluene *
1 ,1 ,2-Trichloroethane *
1 ,1 ,2-Trichloroethylene
n-Tridecane *
Trimethyl-trioxo-
hexahydrotriazlne
isomer
Triphenyl phosphate *
n-Undecane *
Undecane-branched isomer
Undecane-branched isomer
Carroll ton
K'ater Plant
0.11
0
0.02
0.08
0.35
D-VOA
0.01
0.07
0.1E
0.02
0.04
0.06
Jefferson 9 1
Water Plant
NO
0.5
ND
0.10
0.45
HE
ND
ND
ND
ND
ND
ND
Oeffsrson £ 2
Water Plant
ND
0.41
ND
ND
0.41
NE
ND
ND
ND
ND
ND
ND
149
-------
KEY TO SYMBOLS USED IN TABLE 65
Symbols used in column headed "Compound"
* While all compounds listed in the table v/cre identified by one or
more methods, those marked with this symbol gained added confirma-
tion by gas chromatography retention time match v/ith an available
standard of the compound.
** Compounds marked with this symbol gained further confirmation by
gas chromatography retention time match with available standards on
each of three different columns, polar and non-polar.
a The quantitative values for these compounds were obtained on
Volatile Organics Analysis by comparison with standards of known
concentration at the Water Supply Research Laboratory. Compound 18
was detected but not quantified in Tetralin extracts of Carrol lion
water at Southeast Environmental Laboratory, but not in Tetralin
extracts of Jefferson Ho. 1 or Jefferson No. 2. The latter labora-
tory did not detect compound 27.
Symbols used in columns headed "Highest Concentration Measured"
D-VOA These compounds were detected by Volatile Organics
Analysis - Bellar Technique only. Quantitative values
have not yet been obtained. Ttvi5 method was performed
only on the Carroll ton water at the Water Supply Research
Laboratory.
D-RE These compounds were detected only on XAO resin
extracts in the specific water for which this symbol
is used. Quantitative values v/ere not obtained from
the resin extracts. The compound may have been detected
and quantified by another method in one or both of the
other waters examined.
D In the one instance where this symbol was used the
compound v/as detected by both the Hater Supply Research
Laboratory and Southeast Environmental Research Laboratory
but not quantified by either laboratory.
NE This symbol means not examined. It is used
exclusively for some compounds reported by the Water
Supply Research Laboratory. This laboratory did not
obtain samples of v/ater from Jefferson No. 1 or Jefferson
No. 2.
150
-------
KEY TO TABLE 65 (Continued)
NO This symbol means the compound was not detected in
that specific water by any of the methods employed.
NYE Compound 39 was confirmed in Carrollton water carbon
chloroform extracts shortly before preparation of this
report. Jefferson No. 1 and Jefferson No. 2 extracts
have not yet been re-examined specifically for compound 39.
151
-------
TABLE 66. MOLECULAR CONSTITUENTS IDENTIFIED
IN NATURAL WATER SAMPLES (615 )
Constituent
p-Cresol
Diethylene glycol
Ethylene glycol
Glycerine
Glycine
Manni to!
Methyl-a-D-glucopyranoside
Methyl-B-D-glucophranoside
Sucrose
Xylitol
Urea
Inositol
0-Methyl inositol
Linoleic Acid
Oleic Acid
Palmitic Acid
Stearic Acid
2,2' -Bipyridine
Sample.
Source
3
5
5
1,2,3,4,5
1
5
4
4
1,5
5
1,2
1,2,3,4,5
1,2,3,4,5
1,5
1,5
1,5
1
4
Concentration
mg/£
7
1
20
1-20
2
2
30
3
2
1
4
0.5-1
0.3-10
1
1
0.4
0.5
4
al - Lake Marion, 2 - Fort Loudon Lake, 3 - Holston River,
4 - Mississippi River, 5 - Watts Bar Lake
152
-------
TABLE 67. PCB CONCENTRATIONS IN
SELECTED WATER COURSES (146)
State
Alaska
Arkansas
Cal ifornia
Connecticut
Hawaii
Georgia
Maryland
Mississippi
New Jersey
Oregon
Pennsyl vania
South Carolina
Texas
Virginia
Washington
West Virginia
Concentration
Water
yg/ i-
ND
ND
0.1 , 0.1
0.1-0.2
ND
--
0.1
ND
0.1
ND
0.2
--
0.1-3.0
0.1
ND
ND
Concentration
Sediment
yg/kg
ND
20-2,400
20-190
40
ND
10-1 ,300
10-1 ,200
50; 170
8-250
15; 140
10-50
30-200
7.9-290
5-80
ND
10
153
-------
PCB's are thus quite persistent in water/sediment systems, and
lifetimes of years or even decades have been postulated (481).
The continued presence of PCB's makes it inevitable that
they will enter the food chain. As they tend to accumulate in
lipid tissues in higher plants and animals, it has been
estimated that PCB's will concentrate up the food chain to as
much as 10' times the water concentration (482).
BIOLOGICAL CONTAMINANTS
An important pathway for certain communicable disease
transmission to man is the consumption of contaminated water.
Direct disposal of wastewater is the principal contamination
route. Land disposal of wastewater is not an
important pathway, as pathogenic organisms have limited mobility
in soil and seldom migrate far enough to contaminate water
supplies (296). However, in contrast to their restricted
mobility in soils, biological contaminants are readily dispersed
and transported by receiving waters. Consequently, there is a
high potential for direct public contact through drinking or
recreational use. Wastewater treatment has diminished this
threat by reducing the number of organisms in the wastewater.
This, combined with natural pathogen mortalities, has greatly
lessened the outbreak of water-borne diseases attributable to
public water supplies.
The environmental factors that influence the survival of
pathogens in fresh water are, in most cases, similar to those
that prevail in marine systems. These factors will be discussed
in greater detail in the marine water section of this chapter.
Briefly, however, the chief factors influencing survivabi1ity
are temperature, pH, sunlight, toxins, predators, and lack of
nutrition, which affect pathogens to different degrees. An
examination of Table 68 reveals that pathogens may survive for
long periods of time and travel great distances before destruc-
tion by environmental factors.
Pathogenic bacteria are best adapted to survival in the
human body or to conditions resembling those found in the body.
Consequently, natural water systems are a hostile environment.
However, cool water is generally more hospitable than warm water
because of the depressed metabolism of both the bacteria and
their predators. Predatory organisms, especially in slightly
polluted waters, are a major contributor to bacterial die-off.
For instance, Barua (35) noted that Vibrio choi erae survived
one to two weeks in clean water as opposed to one to two days in
water with a large bacterial population.
Pathogenic bacteria also suffer from a lack of proper
nutrition in clean waters; low nutrient levels prevent reproduc-
tion. Since die-off rates exceed growth rates, the overall
154
-------
en
tn
TABLE 68. AVERAGE TIME IN DAYS FOR 99.9% REDUCTION
OF ORIGINAL TITER OF INDICATED MICROORGANISMS IN WATERS (595)
Microorganism
Poliovirus I
ECHO virus 7
ECHO virus 12
Coxsackie virus A9
Aerobacter aerogenes
Escherichia coli
Streptococcus fecal is
28°C
17
12
5
8
6
6
6
Little Mi
River (Oh
20°C
20
16
12
8
8
7
8
ami
io)
4°C
27
26
33
10
15
10
17
Ohi
(
28°C
11
5
3
5
15
5
18
o River
Ohio)
20°C
13
7
5
8
18
5
18
4°C
19
15
19
20
44
11
57
-------
pcpulctiort vn 11 decline, Other factors affecting die-off are
L": tra\-(C" e.t r-cc-'ati or. ~r Sunlight, pH extremes, natural anti-
biotics, end chemical toxins,
In contrast to bacteria, viruses do not multiply in water
ere. therefere, their number In a water body can never exceed
the number introduced into that body by waste disposal. Typi-
cally, viruses are much more resistant to external environmental
factors (chemical content, pH, temperature, time, etc.) and
survive longer than bacteria (136, 198). It was long suspected
that f'gcf cca'ld inactivate viruses through some process because
of low virus concentrations in algae-rich waters. However, it
is now believed that the high pH and dissolved oxygen in the
vicinity of algal blooms are responsible for the inactivation.
Virus inactivation in lake water is further enhanced by
the presence of proteolytic bacteria which degrade the viral
coat (292). Coxsfcckie is particularly susceptible to proteolytic
bacteria, while pcl'O virus is generally resistant except to
Pseuc-omonas aeryginosa (292). Otherwise, the mechanisms rf virus
removal ere obscure. lable 69 reports survival times for various
enteric viruses in fresh-water bodies.
Transport mechanisms for pathogens include physical current
motion, organism motility, adsorption, ingestion, and aerosoli-
zation. As most pathogens readily adsorb onto suspended matter,
sediment pathogen concentrations may greatly exceed water con-
centrations. Filter feeding organisms, such as fresh-water
shellfish, tend to concentrate pathogenic organisms. Conse-
quenfy, shellfish can be a major factor in the spreading of
certain communicable diseases.
156
-------
TABLE
IK WATER
Type of Water
River water
Impounded fresh
water
-
V i rus
Cp\5*rlc-?f> S-3
ECHO 5
Polio 1
Coxsackie B-3
ECHO 12
ECHO 7
Coxsackie A-9
Polio 2
Polio 3
ECHO 5
Ccxsackie A-9
ECHO 12
Polio 1
Polio 1
ECHC 7 '
Polio 1
Polio 3
Polio 3
Coxsackie A-2
Coxsackie A- 2
Coxsackie B-5
Ccvsackie E
Cnxsarlif F-3
Polio 1
ECHO 7
ECHC 6
Coxsackie A-9
Polio 1
Coxsackie ?
ECHO 12
Polio ?
ECHO ?
ECHO :
Polio ?
Polic ?
ECHO ?
Temr-e
*-fc
7 t: ?
7/0.5
7/1
7/1.7
19/3
15/3
10/3
75/3
SO/3
60/3
? C / 3
33/3
19/3
60/3
2t 5
27/3
50/3
67/3
-
-
-
'f T
"7 ,' 1 t
1 / ") . 5
22/3
t t
e/3
2 " ' 3
18/3
H/3
21/3
23/3
2 ": .' c
52/3
52; 3
42/3
r2u.re °f
iS-16
res- c* Daj
P/3
-
-
-
-
-
-
15/3
8/3
15/3
_
-
-
45/3
-
-
18/3
7/1 .3
-
-
24/1
-
_
-
-
-
-
-
-
-
-
-
.
-
-
-
20-25
o *>
3/3
3/3
3/3
5/3
7/3
8/3
S/3
S / 3
8/3
E/3
12/3
13/3
16/3
16/3
20/3
-
7/2.1
5/2
47/2
_
-
3 ' 3
3/3
4/3
F ' 3
6/3
6/3
8/3
5/3
10/3
12/3
20 3
21/3
C i- / 3
24/3
157
-------
SECTION 9
CONVENTIONAL WATER TREATMENT: CHEMICAL COAGULATION AND
FLOCCULATION FOLLOWED BY SOLIDS SEPARATION
INTRODUCTION
Chemical coagulation and flocculation, followed by clari-
fication or filtration, is common water treatment practice for
the treatment of surface waters. The primary purpose is to
remove suspended and colloidal solids.
The overall process takes place in three distinct phases.
Coagulation involves destabi1ization of the colloids by rapid*
mixing of the chemical coagulant with the water in some type
of agitated rapid mix tank. Retention time in rapid mixing
is very brief, on the order of a few minutes. Flocculation
follows in which the wastewater is gently stirred with paddles,
allowing the particles to collide and aggregate into larger
floes. Depending on temperature, concentration of the solids,
and the type and dosage of coagulant, flocculation requires from
15 minutes to one hour. Clarification and/or filtration
usually follows, to provide solids separation.
Commercially available flocculator-clarifier units (often
called solids contact units) combine all three operations in
a single compartmented tank. In a typical design, coagulant
is fed and mixed with the wastewater at the influent pipe;
flocculation occurs in a central cone-shaped skirt where a high
floe concentration is maintained. Flow passing under the skirt
passes up through a solids blanket and out over surface weirs.
These units are particularly advantageous for lime softening of
hard water, since the precipitated solids help seed the floe,
growing larger crystals of precipitate to provide a thicker
waste sludge. Recently, flocculator-clarifiershave been receiv-
ing wider application in the chemical treatment of industrial
wastes and surface water supplies. The major advantages promot-
ing their use are reduced space requirements and less costly
installation. However, the unitized nature of construction
generally results in a sacrifice of operating flexibility.
158
-------
The primary substances used as coagulants and their
reactions are described below:
1. Aluminum sulfate + calcium bicarbonate
A12(S04)3 + 3 Ca(HC03)2 = 3 CaS04 + 2 A1(OH)3 + 6 C02
2. Aluminum sulfate + sodium aluminate:
6NaA102 + A14(S04)3 . 18
6H
8A1(OH). + 3NaSO
3. Aluminum chloride (used under exceptional circumstances
only) :
2 A1C13 + 3 Ca(HC03)2 = 2 A1(OH)3 + 3 CAC12 + 6 C02
4. Aluminum sulfate + hydrated lime-
A12(S04)3 + 3 Ca(OH)2 = 3 CaS04 + 2 A1(OH)3
5. Ferric sulfate:
Fe2(S04)3 + 3 Ca(HC03)2 = 2 Fe(OH)3 + 3 CaS04 + 6 C02
Ferric sulfate + hydrated lime:
Fe2 (S04)3+ 3 Ca(OH)2 = 2 Fe(OH)3 + 3 CaS0
Ferrous sulfate:
FeS04 + Ca(HC03)2 = Fe(OH)2 + CaS04 + 2 C
Ferrous sulfate + hydrated lime:
FeS0
4 + Ca(OH)2 = Fe(OH)2 + CaS04
Ferrous sulfate + chlorine
2 FeS04 + 3 Ca(HCO,)? + C19 = 2 Fe(OH), + 2 CaSO, +
CaCl + 6 C0 ^ 2 2 3 4
6
7
8
9
The most commonly used coagulant is Al?(SOA)o . 18 HoO,
which is known as filter alum. The amount of hydrolysis which
occurs when filter alum is introduced to the water is a function
of the pH of the water, with optimum efficiency achieved at a
pH of 7 to 8(506) .
Because chemical coagulation and clarification is
probably the most popular water treatment technique, there
exists a substantial volume of information on this technology.
Table 70 summarizes the available literature located during the
study. As shown in the table, most research work has been
performed on the elemental group of contaminants as many of
the metals are most efficiently removed by chemical precipita-
tion. Substantial study of turbidity removal and virus in-
activation/removal have also been conducted. With the current
focus on synthetic/organic and biocidal contaminants in water
supplies and their potential carcinogenic effects with long-
term ingestion, a surge in research in these areas is anticipated
159
-------
TABLE 70. LITERATURE PERTAINING TO CHEMICAL COAGULATION
AND CLARIFICATION
Contaminants
Reference Number
Water Quality Parameters
Asbestos
COD
Color
Hardness
Suspended solids
Turbidity
Elemental Contaminants
Antimony
Arsenic
Barium
Cadmium
Chromium
Cobalt
Iron
Manganese
Mercury
Molybdenum
Nickel
Selenium
Vanadium
374, 375
575
226, 414, 575
141
93
9, 137, 157, 225, 226, 274, 548, 575
537
39, 99, 157, 275, 280, 396, 491, 576,
577
39, 396, 506, 588
39, 157
157
470, 480, 537
130, 157
130, 157
157, 394, 506
537
537
157, 506
537
160
-------
TABLE 70 (continued)
Contaminants
Biocidal Contaminants
DDT
D i e 1 d r 1 n
Endrin
Lindan.e
Parathion
537,
537,
537,
546
40
Reference Number
546
546
546
Synthetic/Organic
Contaminants
PAH (Polynuclear
Aromatic Hydrocarbons) 284
PCB 352
TTHM (total trlhalo-
methanes) 632
Biological Contaminants
Bacteria 14, 56, 112, 113, 116, 198, 435, 547,
575, 639, 643, 700
Virus 112, 113, 547
161
-------
WATER QUALITY PARAMETERS
Asbestos has recently been implicated as a carcinogen of
potential danger to workers breathing the fiber in asbestos
manufacturing plants. Thus, it is feared that the incidence
of asbestos in drinking water supplies may also be a health
hazard .
Several studies have investigated the ability of chemical
coagulation followed by clarification and/or filtration to
remove asbestos from water intended for potable purposes.
Lawrence et al. (375) examined the effectiveness of various
methods: straight filtration, diatomaceous earth filtration,
chemical coagulation and combinations. The most effective
method involved chemical coagulation with iron salts and poly-
electrolytes followed by filtration, which resulted in better
than 99.8 percent removal from water containing 12 x 106
fibers/^ . The optimum ferric chloride dosage was found to
range from 6 to 8 mg/£ ; satisfactory floes were formed at all
test temperatures. Other reported removal efficiencies were
reported as follows:
% Asbestos Fiber
Treatment Removal
Ferric chloride, polyelectrolyte
coagulation and filtration 99.8
Graded sand filtration only 90
Diatomaceous earth filtration only 96.8
. Bentanite clay, polyelectrolyte
coagulation and filtration 99
As a continuation of the above effort, Lawrence and
Zimmermann (374) studied the optimization of alum and polyelectro'
lyte coagulation for asbestos removal. Optimum removals were
obtained with alum concentrations of 30 to 50 mg/a and poly-
electrolyte values of 0.3 to 0.6 mg/a . Asbestos removals of
over 99.9 percent were achieved. Rapid coagulation and direct
filtration was also evaluated and the performance found to be
comparable to conventional treatment employing flocculation and
sedimentation. In addition, a survey of turbidities and fiber
concentrations for several municipal water supplies indicated
no correlation between these two parameters.
Shelton and Drewry (575) evaluated the effectiveness of
various coagulants in the removal of COD from a raw surface
water supply. Results are summarized in Table 71.
162
-------
iABLE 71 . A COMPARISON OF THE EFFECTIVENESS OF THE COAGULANTS TESTED
ON THE RAW SURFACE WATER (575)
CO
Coagulant and
Coagulant Aids
A12(S04)3
FeCl3
Fe2(S04)3 . nH20
Cationic flocculant
A12(S04)3 +
Cationic flocculant
A12(S04)3 " +
t. to
Nonionic aid 1
A12(S04)3 +
Anionic aid 1
A12(S04)3 +
Anionic aid 2
A12(S04)3 +
i. to
Nonionic aid 2
A12(S04)3 +
Na9OAl 90,
C, C* «3
Coagulant
con-
centration
mg/fc
15
34
35
0.56
8 +
0.25
10 +
0.25
10 +
0.2
9 +
0.2
10 +
0.2
10 +
12
""' - -'--- ~~~ '-"-"-
Maxi-
mum
Turbidity
Removal
percent
96.50
94.80
90.50
46.0
97.4
97.4
99.65
98.6
97.20
98.70
.^^^^i^^B*"*""""""""""^^^^""
Coagulant
con-
centration
mg/£
20
48
38
0.51
8 +
2.25
10 +
0.5
10 +
0.4
10 +
0.2
71
+
0.4
10 +
9
Maxi-
mum
COD
Removal
percent
43.0
73.0
88.50
26
49.5
59.3
97.5
79.5
85.00
86.00
Optimum
Dosage*
A B
12 14
37 32
65 42
t 1.5
9.2 7.2
0.25 0.25
9 9
0.4 0.16
8.2 |
0.4 t
7.1 1
0.2 |
64 54
0.4 0.4
10 |
Q t
y t
se
Isoelectric point was not reached with test dosage.
More than one isoelectrici point was indicated.
-------
Mey conducted tnat aiumirijin suifate was the most effective
coaguiant *or COO removal. Cationic poi velectrolyte additions
*«"« 'i* '**,;: ,i ,.7:'i i7-,;-rT,; jTjs ,^d , 3' 3dtt9r. results.
Color is caused by numus, tannins, weeds, algae, soluble
wastes, and to a certain extent, metals (632). In itself, color
is not a hea tn Jiazard; however, it signals the presence of dis^
solved organics and metals that may be of some health concern
Ii«??nie/E?!?arC£erS-eval?ated C°1or removal in the same inves-
tigation (575). Ferric chloride was found to perform erratically
at differing dosages. Excellent removals were achieved at a *
35 aig/i. out it dosages around 35 m^/ i' ,n«j 50 mg/t!, color was
significantly increased. A study by Mangravite et! al (414)
showed t>jat removal o* V^>7 ,^d r0,? s^!jrce Qf color $n ^^
>jp3,»i-si jy ir.,.-.ji- ^:j-.,;-t p-CJIi0:;(j ,;ie 3J.ne hi ^ percentaqe of
removals as the conventional coagulation/sedimentation technique
but at .a rar.9 0, 5 tc ?J ,,rnes faster F , t and 8 (226)
investigated the use of aTum with 13 coagulant aids for color
reroova,. v,?r.rnam aljsn Jasages ranged from 20 to 25 mg^ and
successfully lowered the color concentration to below five stan-
dard units. The use of irot saUs, oxViation, adsorption, or
po;/7ie"5 j:^3 ;:a'J ,TJ: i.vvavi :l:s !d>e^ of removal.
jr-jTjss -i.n-:/r ,;,! jn- ^.> -oas ^-edom^na fitly) via lime
soaa prtjcipitdtirfa scjfiening is a common practice at many water
soft water has g-na^My been considered
f f T-^'ii ?T t::u: ? z raauces cne usage of soap and detergents
tastes better, and reduces scaling and precipitation in pipes '
rnnn*'1CM«??'i1:2r3 * -v«* ' * " 3 * "e - - " - stjuies, summarized by
Looper (141) have discovered an apparent inverse relationship
between hardness arjjftenrtg process may nave to be reevaluated.
, il ">'o.n w-i-ie- supplies by coated
and uncoated diatomite filter was evaluated by Burns et al. (93)
They found that special polyelectrolyte coatings were useful
For a final polishing filter process, but that these aids were
not as effective as conventional filter aids where large amounts
or suspended solids had to be removed.
T-jr!3icHt/ is J iT-vn^ nejiur-eo *at«r q^jtlity parameter
inversely related to the visual clarity of the water. Turbidity
is caused by clay and other colloidal matter which in themselves
are or no health concern. However, nea^y metals, virus, and
bacteria may be adsorbed onto the clay particles, and the removal
of turbidity can be of imoortance in regards to potential long!
term nealth effects. because of ,ts poouUrisy as a quality test
many studies or turbt^ty removal lave been performed as '
summarized below. Robtnson (543 compared the effectiveness of
164
-------
alum versus polyelectrolytes for removal of turbidity from muddy
surface water. Figure 4 summarizes the De!"fo~
-------
4. The optimum paddle speed ranges between 40 and 50
rpm.
5. The optimum flocculation time was approximately 30
mi n.
6. This study revealed that the significant interactions
between the independent variables (alum dosage, floc-
culation time, and paddle speed) can be utilized in more
efficient water treatment. For example, a higher
percentage removal of turbidity can be obtained by
using low alum dosage and increasing the flocculation
time and/or paddle speed. On the other hand, high
alum dosages and reduced flocculation times and/or paddle
speeds can be utilized.
7. The study shows the importance of the following equip-
ment and methods in the removal of turbidity in water
treatment plants:
a
b
Variable speed flocculator paddles.
Multiple flocculation basins that can be used in
series or parallel operation.
c. The use of jar tests to determine the optimum alum
dosage continuously during the operation of water
treatment plants.
Gruninger et al . (274) compared the performance of ferric
chloride versus alum as the primary coagulant and found that
the combination of 8 mg/A Fed- + 4 mg/s, bentonite clay + 0.25
mg/ji polymer provided comparable performance to the system with
alum and clay; there was approximately 95-98 percent turbidity
removal.
Reference 157 summarizes the performance of various treat-
ment technologies in removing turbidity. These results are -
Plain sedimentation: 50 to 95 percent, depending
totally on the settling characteristics of solids;
Coagulation with sedimentation: 80 to 99 percent;
Rapid sand filtration: 80 to 99 percent with influent
turbidity of 10 JTU or less;
0 Slow sand filtration: 80 to 99 percent with influent
turbidity of 10 JTU or less;
Diatomite filtration: 80 to 99 percent with influent
turbidity of less than 10 JTU.
166
-------
Shelton and Drewry (575) analyzed the effectiveness of
different cationic, nonionic, and anionic polyelectrolytes in
reducing turbidity. Table 71, presented earlier, displays their
results. Aluminum sulfate with anionic coagulant aids was found
to be the most effective, achieving 99+ percent removal at a
10 mg/£ dosage. Frissora (225) evaluated the performance of
rapid multimedia filtration alone on turbidity removal and
achieved removals of 96 to 99.7 percent at high loading rates of
4 to 16 gpm/ft2. Conley (137) also studied rapid filtration
preceded by chemical coagulation and settling, for turbidity
removal at a number of water treatment plants around the country,
Table 72 summarizes the results of his study; removals ranged
from 80 to 97 percent and averaged 94 percent.
ELEMENTAL CONTAMINANTS
Many elemental contaminants are readily removed by chemical
coagulation and subsequent solids separation steps (settling or
filtration). As some of the elemental contaminants are being
more closely reviewed for possible long-term health effects, the
importance of chemical coagulation as a removal process becomes
more pronounced .
TABLE 72. TYPICAL THREE-MEDIA HIGH-RATE FILTRATION PLANT PERFORMANCE
Location
Regina, Sask.
Siler City, N.C.
Pasadena, Tex. (industrial)
Corvallis, Ore.
Ocaquan, Va.
Samoa, Ca. (industrial)
Fort Lauderdale, Fla.
Knoxville, Tenn.
Albany, Ore.
Long view, Tex.
Paris, Tex.
Newport, Ore.
Norristown, Pa.
Springfield, Mo.
Winnetka, 111.
Stanton, Del.
Turbidity
Applied Filtered
JTU JTU
0.5
1
3
3
1
10
1
1
2
4
10
3
6
1.5
2
2
0.1
0.2
0.5
0.2
0.1
0.5
0.1
0.2
0.2
0.2
0.3
0.2
0.3
0.2
0.3
0.2
Filter
Rate
gpm/ft2*
4
5
6
3
4
5
4
5t
5
3
3
4
4
4»5
5
4
Filter
Runs
hr
30
30
40
50
48
18
80
60
20
48
50
20
45
24
15
30
Backwash
Water
percent
2
2
1
1
1
2
1
1
2
2
2
3
1
1
2
3
* Typical summer peak daily flow rate. Hourly peaks
are generally in the range of 4-6 gmp/sq ft.
t Under test. Some filters are out of service so
that rate could be increased on remaining filters.
167
-------
Arsenic is one element being closely watched in water
thnHS 3S H\hSSKa relat1vely h19" toxicity, accumulates in
the body, and has been associated with the occurrence of cancer
(39) Several studies on arsenic removal are available. Some
JlSn^T-5 21 black-f°°t disease and skin cancer have been
reported in the southwest part of Taiwan. According to
statistical data, there is a close relationship between these
diseases and the high arsenic content (0.6 to 2.0 mg/£) in
deep-well water used for drinking (577). Since there is no other
iirl SlJhJST S°UrCe !un the area' some P^^ical and econo-
mical method to remove the arsenic compounds was urgently
needed To satisfy this need, Shen (576) performed a lengthy
ISSl^JV* *reatabH1ty tests to evaluate the arsenic Removal
capability of coagulation/settling/filtration processes
Initial coagulant tests showed ferric chloride to be the best
chemical, achieving 92 percent As removal at a 30 mq/£ dosaae
Subsequent testing, however, showed that these removals could'
be improved by preoxidation before coagulation. Adding 20 nq/t
of chlorine and then coagulating with 50 mg/£ of ferric chloride
provided the best results, achieving 98.7 percent As remova?
*ff0HKu (275)sh°wed that As removal was
affected by PH and doses of suitable coagulants. Arsenic
adsorption onto ferric hydroxide exceeded adsorption onto
?miHnhin/J?lde- 1^ "?0tt? C0a9ula"ts, increased dosages
rfoJj^e 9/ } r
168
-------
The toxicity of antimony is similar to arsenic, although
less acute. Very little research has been conducted related
to Sb, as other metals appear to be of more importance from
a health-effects standpoint. Lime coagulation has been shown to
provide Sb removals of better than 90 percent from wastewater
effluent (537). Similar removals may be possible in water
supply treatment, but no data was found.
Barium is a toxin that acts as a muscle stimulant. As
such, it strongly affects the heart muscles and causes high
blood pressure and nerve blockage (39). Barium removal -
only for wastewater treatment - was reported by several re-
searchers. Sigworth and Smith (588) found during pilot waste-
water plant tests that lime coagulation and settling was an
effective method, resulting in a 99 percent Ba removal. Dosage
rates were 45 mg/£ FeCla, 260 mg/£ lime plus 20 mg/t FeCl3 for
the low lime test, and 600 mg/£ lime for the high lime run.
Logsdon (396) found improved removals with the lime softening
process. Treatment efficiency was pH dependent, increasing
to a maximum of 98 percent at pH 10.5, and dropping off at
higher pH values. Barium is not appreciably removed by ferric
or alum coagulation.
Cadmium has a high toxic potential, accumulates in the kid-
ney and liver, and has been suggested as a causative factor in
high blood pressure (157). Only minute traces of cadmium are
found in natural waters. However, several industries discharge
cadmium in their wastewaters, including metallurgical alloying,
ceramics manufacture, electroplating, inorganic pigments,
textile printing,- chemical industries, and acid mine drainage.
Very little data are available regarding the use of coagulation
for Cd removal at water treatment plants. The summary reference
(157pists removals at 50 to 90 percent with coagulation followed
by filtration. Unpublished data developed by EPA indicates
that lime softening and ferric sulphate coagulation above pH 8
achieves Cd removals of over 98 percent.
Chromium in the hexavalent form is highly toxic to man
and has been shown to be carcinogenic to man when inhaled.
Volkert and Associates, In a study for EPA (157), summarized
that coagulation and sedimentation with filtration is capable
of removing 50 to 90 percent of the insoluble chromium (Cr)
forms present in water supplies.
The hexavalent form is much more difficult to remove with
typical water treatment coagulants than is the trivalent form.
It is desirable, therefore, to reduce the chromium present
to trivalent prior to treatment. Laboratory studies by EPA
(unpublished) indicate that trivalent chromium is removed at
better than 95 percent levels by ferric sulphate up to pH
9.5, removed at 90 percent levels by alum up to pH 8.5, and
removed at 98 percent level by lime softening at pH from 10
169
-------
to 11.5. Hexavalent chromium, however, is not effectively
removed by any of these coagulants. Cobalt (Co) concentration
in potable water sources seldom reaches levels that require
special consideration. Cobalt is currently best treated by
lime coagulation, although as much as 2 mg/t may be left in
the effluent (537). Nilsson (480) found that lime coagulation
was capable of achieving 88 percent removal of cobalt. Another
study (470) found that cobalt precipitation could be enhanced
by the addition of chitosan or a chelate as a polishing agent.
An EPA study (537) concluded that similar precipitation techni-
ques are also applicable to molybdenum (Mo), nickel (Ni), and
vanadium (V) removal.
Iron and manganese, often found together, are important
constituents of potable water supplies because they can import
unwanted aesthetic qualities. From a health standpoint, how-
ever, iron and manganese do not pose any significant threat
in the concentrations normally found in surface and ground-
water supplies. Therefore, removal of these constituents will
not be discussed in any depth here. Effective removal can be
provided by aeration or more commonly, by chemical precipitation,
sedimentation, and filtration (130).
Recent attention has been focused on the contamination of
water supplies by organic and inorganic mercury (Hg) by
industrial discharges. Fortunately, recent rests by the EPA of
273 water supplies across the country showed very low mercury
levels in nearly all of them. Even so, the performance of
conventional water treatment technologies and new techniques for
removing Hg from water is of interest. Logsdon and Symons (394)
investigated the efficiency of conventional water treatment
processes in removing Hg. Bench scale studies of chemical
coagulation and settling yielded the following conclusions:
1. Mercury removal during coagulation was related
mainly to adsorption of mercury onto the
turbid-causing agents in the water.
2. In raw waters with low turbidity, ferric sulfate
was more effective than alum for removal of
inorganic mercury. Removals ranged from 40 to
60 percent over a turbidity range of 2 to 100
JTU's.
3. Removal by coagulation or adsorption onto turbidity-
causing agents was less for methyl mercury than
for inorganic mercury.
170
-------
4. Inorganic mercury removal by softening was most
effective in the pH range of 10.7 to 11.4 and
is thought to be related to adsorption onto
magnesium hydroxide floe.
5. Methyl mercury was not removed by softening.
The authors concluded by stating that as long as environ-
mental levels of mercury in raw water remain low (near drink-
ing water standards), extremely high removals will not be
required, and conventional technology should be sufficient.
Molybdenum can occur naturally in drinking water supplies
at concentrations up to 20 vg/£ due to weathering of minerals.
It can also be found in water as a result of waste discharges
from industries related to the manufacture of glassware,
ceramics, printing inks, electrical equipment, and certain
steel alloys. Virtually no data relative to molybdenum removal
from water supplies are available, because molybdenum is not
currently seen as a primary health hazard.
Nickel occurs naturally at concentrations up to 0.072 mg/£
with an average concentration of about 0.005 mg/£. Wastewater
discharges from industries associated with nickel-plating,
nickel alloying, storage battery manufacturing, organic hydro-
genation, and the manufacture of nickel-chrome resistance wire
can contribute to the presence of nickel in water sources (21).
In large doses, Ni can be harmful; however, in this country,
natural concentrations are low, and lime coagulation appears to
be successful in removing large percentages of Ni from waste-
water. No literature pertinent to Ni removal by water treatment
facilities was found.
Alum and ferric sulfate coagulation and lime softening
are only moderately effective for selenite (Se+^) removal,
and are largely ineffective for selenate (Se+°) removal (396).
Studies with ferric sulfate (30 mg/£) at a pH of 5.5 yielded
removals of 85 percent from river water containing 0.03 mgSe H/£.
Removals decreased as the pH increased. The maximum achievable
Se+4 removal with alum (100 mg/£, pH 6.9) was 32 percent. A
maximum removal of 45 percent was obtained with lime softening.
No conventional method achieved greater than 10 percent removal
of Se+6.
No data were located relative to vanadium removal from
water supplies. In wastewater treatment, however, very good
vanadium removals were achieved via coagulation with iron or
aluminum salts or chitosan polymers (537).
171
-------
310CIDAL CONTAMINANTS
Recently, there has been increased a'.v.j"e>ie ?> cf the
potential health hazards of biocidals. Limited data, however,
are available in the literature regarding the removal of
these constituents from water supplies by chemical coagulation
Robeck et al. (546) studied the effects of various water treat-
ment processes on pesticides. Their results, in regards to
pesticide removal via chemical coagulation (alum) and filtra-
tion, are shown in Table 73 below.
TABLE 73. PERCENTAGE OF PESTICIDE REMOVED BY
CONVENTIONAL WATER TREATMENT (546)
Pesti cide
Load - ppb
10
25
Lindane
Dieldrin
DDT
Parathion
2, 4, 5-Tester
Endri n
-------
SYNTHETIC/ORGANIC CONTAMINANTS
In recent years, con.e^n ias }«ei exsf*>52J omr tne
possible occurrence of certj'n ci-^ao-^jo'<'c .-^mounds In
drinking water (World Health Organization, 1964). A group
of compounds which has received particular attention is the
polynuclear (polycyclic) aromatic hydrocarbons (PAH), some
of which are potent carcinogens under certain conditions. It
is, however, far from certain that these compounds are signi-
ficant when present in the trice mounts found In drinking
water. Clearly, further research is T??ded into both the
levels and health effects of :3A,i i i uie en* < ronmenc ('-'84j .
Harrison et al. c jnc 1 ujs \Z84; : 'Tie --^1 'ab'i M ty of much
of the information concerning tna removal of PAH by conven-
tional water treatment processes is open to considerable doubt.
Field experiments hava frequently ignored retention times
within the works, and hence been rende-ed unreliable at the
sampling stage. Laboratory studies nave commonly used unreal-
istic high concentrations of PAH, and the high removals achieved
may be largely explained afcen D/ :<«.? 'ow sjiubiiity af the
PAH themselves. Further analytical work is required in this
field, and fundamental studies o* the cheoncaT changes that
occur upon chlorinati aa jf *ie.>'i co»n': ju 7 Js i: 'o«» concentrations
are necessary. Increasing water reuse makes the ne-?d for t*ii$
type of information par tic -j ar' y aci-.i '
After the EPA disclosed its ^inj:; !ig$ o' or^oe^!?s
Mclndoe (435) summari *ea rase-arci ? n :i*j area as fc!-cws:
-------
t Work by the U.S. Army Engineering Research and
Development Laboratories at Fort Belvoir, Virginia,
showed that a diatomite filter using a coarse grade
of filter aid was capable not only of 100 percent
removal of the entamoeba cysts, but also of partial
removal of other pathogenic organisms. Work done
at Rutgers University has shown that even the
coarsest grade of diatomite gave coliform removals
of greater than 50 percent for influent levels of
210 to 1300/100 ml. Finer grades gave "complete"
coliform removals of influent levels up to several
thousand per 100 mi.
9 Work by Chang (112, 113), Hunter (313), and
others with solutions of iron salts added to bacteria-
contaminated water has indicated a reaction takes
place between the iron ions and the protein sheath
of both bacterial and viral organisms. Subsequent
removal of the iron by the diatomite MgO process
has produced total count reductions on the order of
99 percent, with fecal strep and Escherichia coli
counts of zero.
t Waters so clarified would be expected to be readily
disinfected by usual practices.
CONTAMINANTS
Amirhor and Englebrecht (14) analyzed the potential
use of uncoated and polyelectrolyte -aided diatomaceous earth
filtration for bacterial virus removal. They concluded that
uncoated DE filtration was not effective for virus removal,
but that precoating of cationic polyelectrolyte greatly
improved removals. Certain variables such as pH, level and
concentration of polyelectrolyte coating, and virus concentra-
tion affected removals.
Wolf et al. (700) conducted a large-scale pilot study of
virus removal by both lime and alum. They demonstrated that
virus removals from secondary effluents by alum coagulation-
sedimentation and coagulation-sedimentation-filtration pro-
cesses are essentially the same as described in the literature
using smaller-scale processes. Removals of bacterial virus
as high as 99.845 percent for coagulation-sedimentation and
99.985 percent for coagulation-sedimentarion-fi1tration pro-
cesses were observed at an A1:P ratio of 7:1.
At a lower alum dose there was a marked decrease in virus
removals. At an A1:P ratio of 0.44:1, removals of only 46
percent of f2 coliphage and 63 percent of polio virus by the
coagulation-sedimentation process per se were observed.
174
-------
High lime treatment of secondary effluents achieved
very high degrees of virus removal, but the percentage has not
yet been quantified.
Englebrecht and Chaudhuri (116) conducted a study to extend
the knowledge in this field. Their conclusions follow:
1. Chemical coagulation and flocculation is an
effective process in removing viruses from
water. Removals in the range of 98.0 to 99.9
percent can be expected.
2. The presence of bivalent cations like calcium
and magnesium up to a concentration of 50 mg/£
each does not interfere with the efficiency of
the process.
3. The efficiency of virus removal is reduced when
the raw water contains organic matter.
4. Intelligent use of commercially available
cationic polyelectrolytes with or without
hydrolyzed metal ions may markedly increase
the efficiency of the coagulation and floccula-
tion process in removing virus.
5. Virus particles remain active in the settled
sludge following their removal from water by
coagulation and flocculation, and can be recovered
from the floe by various eluants. Therefore,
proper care should be taken in sludge disposal.
Thorup et al. (643) conducted a study to determine the
effectiveness of polyelectrolytes used as coagulant aids
for the removal of virus from artificial ly seeded water. They
found that the cationic polyelectrolyte performed more
acceptably than the an ionic and nonionic types and was benefi-
cial in aiding floe formation under conditions of poor coagula-
tion. However, the 80 to 94 percent removal achieved under
these circumstances was well below the 99+ percent usually
considered acceptable. In instances of adequate coagulation,
however, cationic polyelectrolytes did not increase virus re-
moval beyond the levels obtained with unaided Al2(S04)3 or
^62(504)3 coagulation.
Shelton and Drewry (575) performed a literature search of
virus (f2 bacteriophage) removal via coagulation and, based
on the results, studied the effectiveness of different chemical
coagulants and polyelectrolytes for this purpose. Their
conclusions were:
175
-------
1. Aluminum sulfate, ferric chloride, and ferric
sulfate are the most promising of the group
of primary coagulants tested, from the stand-
point of f2 bacteriophage removal, all produc-
ing greater than 99 percent removal. Aluminum
sulfate is considered to be the most effective
coagulant, whereas ferric chloride and ferric
sulfate are less effective.
2. The cationic polyelectrolyte tested is not
satisfactory as a primary coagulant because of
its poor floe formation and settling characteris-
tics. Virus removals with the cationic flocculant
were only moderate (92 percent).
3. Anionic, nonionic, and cationic polyelectrolytes
have only minor significance in virus removal.
It is noted, however, that the anionic coagulant
aids are useful in widening the effective dosage
range for good virus reduction. The nonionic
coagulant aids give moderately better results,
which are attributable to an ability to form more
dense and "sticky" floe. This improvement of virus
removal is indirect, because the nonionic poly-
electrolytes do not form a virus-ion complex with
the virus protein coat. The cationic coagulant aid
produces a moderate improvement in virus removal;
however, it is questionable if this improvement
would be economically justifiable for a full-
scale operation.
4. The use of sodium aluminate with aluminum sulfate
does cause a marked increase in virus removal,
to 99.9 percent overall. This increase, however,
could be used only for "special-case" situations,
since the sodium aluminate dosage for optimum virus
removal is not compatible (by a factor of 3) with
turbidity and COD optimums.
Thayer and Sproul (639) of the University of Maine did
extensive research concerning the effects of water softening
upon virus inactivation. Their primary objective was the
determination of the effect of chemical precipitation in water
softening upon bacterial viruses. Inactivation of T2 virus
varied widely, with the best results, on the order of 99.999
percent inactivation, occurring when magnesium hydroxide was
the only precipitate formed. The standard excess lime-soda-
ash process also produced good results with about 99.45 per-
cent virus reduction.
176
-------
Lime f 1 occulation with rapid sand filtration, a long-used
standard water-treatment, method, was investigated for its
virus-removal characteristics by Berg et al. (56) at the
Cincinnati Water Research Lab. Conclusions based on their
study using polio virus I (nacuine) exclusively were that
(1) flocculation of secondary effluent yielded up to 99.86
percent removal of the virus, dependent upon the coagulant
dose and the pH level attained, and (2) the total removal by
lime flocculation and rapid sand filtration through an 8-in-
deep filter achieved a maximum of 99.997 percent.
The Journal of the Sanitary Engineering Division, ASCE,
published an article in 1961 summarizing the virus work done
up to that time (198). Table 74 shows the results of this
work. As shown, the dosage of flocculant alone is not a
measure of the efficiency of the process.
Robeck et al. (547) investigated the fate of human viruses
in rapid filtration processes with and without flocculation and
settling. They found that if low alum doses were fed just
ahead of the dual-media filter (operating at 6 or 2 gpm/ft^),
more than 98 percent of the virus was removed. When the alum
dose was increased and conventional flocculators and settling
added, removals were increased to over 99 percent. When turbid
water was treated, a floe breakthrough was usually accompanied
by an increase in virus penetration. Polyelectrolyte doses
as low as 0.05 mg/£ increased floe strength and helped to
prevent such breakthroughs.
The current state of knowledge indicates that chemical
flocculation, settling, and filtration are effective in remov-
ing virus from water. Removals of 99*percent have been reported
under proper operating conditions. However, more research is
still needed in the area to fully determine the most effective
doses of coagulants and coagulant aids, the physiochemical
effects of turbidity, pH, temperature, and colloidal charge,
and to develop optimal operating parameters.
Chang et al . (113) performed comprehensive studies of the
dynamics of removal of bacterial virus by aluminum sulfate
flocculation. From their observations they concluded:
1. Flocculation by aluminum sulfate can remove high
percentages of virus, and within the zone of
flocculation, higher doses produced greater
efficiency.
2. The virus is concentrated in the floe sediment
and is not destroyed, but only temporarily
inactivated. It will become active again, if
dissociated from the aluminum.
177
-------
TABLE 74. REDUCTION OF HUMAN ENTERIC VIRUSES IN
WATER BY CHEMICAL FLOCCULATION (.198)
Virus
Polio
Polio
Infectious
hepatitis6
Coxsackie A5
Coxsackie A2
(purified)
Type of Water
Tap
Raw
River
Distilled
Spring
Ohio River
(16-255ppm
turbidity)
Stages
1
1
1
1
1
1
1
1
1
1
2
2
Coagulant
Added*
ppm
100
100
136
410
136-273
273-546
69
28-45
15
25
15
15*
25
25*
Floe Amount
or
Description
0.4-1.03
mi per 1
1.5-2.2
mi per 1
Good
Very good
Very good
Very good
Very good
Very good
Virus Removal
Little6
Some0
Some to
significantd
Some
Little to some
Significant
Little to some
Some
95.7% at 25°C
95.9% at 5°C
98.6% at 25°C
99.8% at 25°C
99.6% at 5°C
99.9% at 25°C
Alum except where marked with an asterisk; asterisks
indicate ferHc chloride.
DProbably less than 25%.
:Probably less than 50%.
JMore than 50%.
2Gauze-strained fecal suspension in distilled water.
178
-------
3. Virus inactivation is believed to be the result
of the formation of an aluminum protein salt
in the virus.
Chang et al. performed another study O12) evaluating the
efficiencies of alum and ferric chloride in removing coxsackie
and bacterial viruses. They analyzed the effects of coagulant
dosage, pH, and rate and method of stirring on virus removal.
A 40 mg/£ dose of Al2(S04)3 yielded an 86.3 percent removal of
coxsackie virus and a 93.5 percent removal of bacterial virus.
Under similar testing conditions, 20 and 40 mg/£ of FeCK
facilitated the following removal percentages: 96.6* coxsackie
virus and 99.3 bacterial virus, and 98.14 coxsackie and 99.9
bacterial virus.
179
-------
DISINFECTION
INTRODUCTION
Disinfection refers to the inactivation or destruction of
pathogenic microorganisms. Disinfectants (chlorine, ozone,
ultraviolet and ionizing radiation) also have secondary applica-
tions, particularly as oxidzrts for the removal of organic con-
taminants. Both applications are included in the literature
pertaining to the treatment of drinking water with disinfectants
(Table 75).
In the United States, the traditional disinfectant is
chlorine, which rf Lfe^ate:1.' . It Is a powerful
oxidant. Both its germlcical and oxidizing properties seem to be
the ^esult cf the *r-"!rpt- rr r* ffvf"?,1 ^ree ^adicaTs in water
(HCp. OH, HOi*). v«r-;-t v' fitted, c'niost all organic compounds.
bl trtv,del cr.c ; 7. ; r 9 ^cc-.Efi6n have been used in pilot
plant and small industrial applications. Like ozone, they seem
to act. by fcrir,1r?c c ff'f* :'" f'-rf "cf'T'cels in water, which can
attacl; crgan-'c bones. i,1 ii'-cv u';tt is incapable of acting at more
than a fev. centimeter de-rtr. prc' both forms of radiation are
highly susceptible tc interference from turbidity and suspended
matter. Ionizing radiation requires radioisotopes and the con-
commitant shieldinc cnc el cti-^-ii.e Scfety precautions.
AH r^ the d*<" r ft ; tf T *. < tf«r cl 5 ?c;vantapes that prevent
any of then* frofri be".r.o urr, vera'; ly applicable. For a given
situation the rhc-r.f dfpprc'f "e^cr-v or the water quality, types
of microorganisms 1r tt-e water, desirability of nondi sinfection
applications, and erst.
180
-------
TABLE 75. LITERATURE REVIEWED PERTAINING TO HATER DISINFECTION
Contaminant
Chlor1nat1on
Water Quality Parameters
/\rnrrr>r> i 3
BOP, '0,0, TOC .
332, 366, 616, 688
332, 555, 616
Elemental Contaminants
Iron
Manganese
Biocldai Contaminants
Chlorinated
hydrocarbons
_, Organo-phosphorus
oo Carbamates
Synthetic/Organic Contaminants
PCBs
General
Biological Contaminants
Viruses, general
Coliforms
E. Coli
Clostridium
Protozoa
91, 157
284, 319, 555, 616
55, 111, 136, 242, 284,
332, 399, 463, 547, 600,
616
111, 366, 537, 555
55, 332, 351, 660
111, 660
Reference Number
Ozonation
3^2, 351, 455, 660
3-2
157, 402, 465
157, 351, 465
91, 157, 332
157, 284, 465
111, 242, 332, 402,
463, 465, 600, 660
61, 111, 283, 332, 537
351, 465, 660
660
111, 332, 660
Radiochenrical
469
157
157
157
157, 352
157
111, 469, 656
-------
WATER QUALITY PARAMETERS
Although disinfectants are seldom specifically employed
to remove any of the water quality parameters, there are certain
chemical reactions that make the idea feasible. The reactions of
chlorine with ammonia are the best known. If allowed to go to
completion, the ammonia will be oxidized to nitrogen gas and will
thus be removed from the water. Ozone does not react with
ammonia ( 332 ) Ammonia is seldom an issue, though, as it is
not a common constituent of most water supplies.
The organics, as represented by BOD, COD, and total organic
carbon, in drinking water are susceptible to oxidation by dis-
infectants. However, reactions other than oxidation may produce
potentially hazardous compounds. For instance, Rook (555) and
McClanahan ( 332 ) reported that chlorine reacted with humic and
fulvic substances, forming chlorinated organic compounds.
These chlorinated compounds are much more resistant than the
precursor compounds to both biodegradation and chemical oxida-
tion. Consequently they persist in a water supply that is not
treated any further than chlorination. Some of the chlorinated
compounds formed are suspected to have carcinogenic properties.
Ozone is even more reactive toward organic compounds than
is chlorine. With ozone, though, the reactions are almost
exclusively oxidation, with few if any hazardous compounds formed
in side reactions. The formation of ozonides and similar com-
pounds has been postulated, but there has been no evidence to
date demonstrating their formation during the ozonation of water.
Morris (465) reported an increase in BOD after ozonation and
attributed it to the breakdown of nonbiodegradable organic
molecules into simple, degradable compounds.
Murphy (469) recently demonstrated that gamma radiation had
an oxidizing effect on organic compounds similar to that of
ozone. Ultraviolet radiation theoretically has a similar effect.
It should be noted that nonbiological contaminants inter-
fere with the primary disinfection role of these chemicals by
consuming the disinfectants. To achieve proper disinfection
in highly organic waters, for instance, requires large increases
in applied dosages. Some water-borne disease outbreaks are
attributed to improper disinfection of highly organic water
supplies.
ELEMENTAL CONTAMINANTS
In general, the disinfectants have no effect on elemental
concentrations. Elements would have to be in a reduced state
before oxidizing disinfectants could have an impact. This is
not likely in most drinking water supplies. Exceptions are
182
-------
iron and manganese, which are more soluble in their lower oxida-
tion states. Morris (465) reported that ozone readily oxidized
soluble iron and manganese to the insoluble oxides, which could
then be removed by sedimentation or filtration.
Trivalent chromium can be oxidized to the hexavalent form,
which is more toxic and difficult to remove with conventional
coagulation/filtration processes.
BIOCIDAL CONTAMINANTS
Chlorinated hydrocarbon biocides are generally resistant
to chemical oxidations. Stone et al. (537) reported that
chlorine was not a particularly effective oxidant for such bio-
cides. Ozone was more effective, but removal efficiencies
varied widely from 16 to 93 percent, depending on the type of
biocide, ozone concentration, and contact time (Table 76).
Stone et al . reported other ozone studies that yielded 50
percent removal of endrin, 75 percent removal of lindane, and
approximately 100 percent removal of dieldrin and aldrin. They
also stated that ultraviolet radiation could completely elimi-
nate carbamate biocides, reduce aldrin by 45 percent, and reduce
endrin and dieldrin by 18 percent.
Buescher et al. (91 ) studied the chemical oxidation of
chlorinated hydrocarbons in water. They concluded the following:
t Lindane concentrations in aqueous solutions were
readily decreased by ozonation and only partially
affected by potassium permanganate. Treatment with
chl orination, peroxides, and aeration had no measurable
effects.
Aldrin in aqueous solutions was readily attacked by
chlorination, potassium permanganate, ozone and aera-
tion; peroxides had no measurable effects.
Dieldrin concentrations in aqueous solutions were
decreased by ozonation and aeration.
Lindane and aldrin in aqueous solution were found to
be volatile. The degree of volatility may be an
indication of the susceptability of that pesticide to
chemical treatment.
Lindane in the presence of other naturally occurring
trace organics found in river water was readily attacked
by ozonation, though aeration had only a minor effect.
183
-------
oo
TABLE 76. EFFECT OF OZONATION ON
CHLORINATED HYDROCARBON INSECTICIDES (537)
Y-BHC Dieldrin DDT TOE (ODD)
Time of
Ozonation
5
10
20
5
10
20
Before After Before After Before After Before
Ozone Ozonation Ozonation Ozonation Ozonation Ozonation Ozonation Ozonation
Absorbed
mg/t ug/*
8.8 1.32 0.88 1.29 1.08
18.3 1.39 0.81 1.30 0.66
36.0 1.31 0.34 1.31 0.22
11.7 2.00 0.54 2.00
20.0 2.00 0.46 2.00
38.2 2.00 0.14 2.00
Aftei
Ozonat
0.62
0.43
0.13
-------
SYNTHETIC/ORGANIC CONTAMINANTS
As previously mentioned under "Water Quality Parameters,"
both chlorine and ozone readily react with dissolved organics.
However, synthetic organics are often more resistant to oxida-
tion than the natural organics. Rosenblatt ( 332 ) indicated
that chlorine reacted with many organics to give both chlorina-
ted and oxidation products, but that there was no reaction with
many others (Table 77). Ozone is an effective oxidant against
the phenolics and organic nitrogen compounds, but not against
many of the simpler organic molecules, such as ethanol .
Harrison et al. (284) reported that chlorine was more effective
than ozone against benzo(a)pyrene.
Many of these synthetic organics, such as nitrobenzene,
benzo(a)pyrene oniline, and ethyl benzene are reportedly
carcinogenic. While these chemicals are seldom found in
drinking water supplies at concentrations exceeding a few ppm,
the postulated no-threshold-dose character of many carcinogens
makes even one molecule a potential hazard. Note also that
chlorine is suspected of producing chlorinated organic compounds
which may themselves be carcinogenic.
Kinoshita and Sunada (352) investigated the effects of
irradation on PCB in water. They concluded that PCB in aqueous
microparticulate colloidal solution is destroyed by ionizing
irradiation (up to 95 percent), but that its resistance to
radiation is far greater than other chlorinated hydrocarbons
used as pentachlorophenol or DDT, and other pesticides such as
parathion. They also found that the acute toxicity of the
irradiated PCB solution was far less than the nonirradiated
solution for striped shrimps.
BIOLOGICAL CONTAMINANTS
The major application of disinfectants is against biological
contaminants. In this light, the disinfectants have been eyaluated
primarily on their effectiveness in controlling biologicals
(e.g., bacteria, viruses, protozoa, parasitic worms).
Chlorine is the traditional disinfectant in the United
States. It is effective to some extent against all types of
pathogenic organisms found in water. Bacterial kills of at
least 99 percent are considered normal (537), and 4 to 5 log
reductions are not unusual . Both Sobsey ( 600 ) and Long
(399 ) reported virus reductions of up to 99.99 percent.
Reference 136 summarized r-esearch on virus destruction by
chlorine as shown in Table 78. Chlorine can be effective when
used with filtration against free-swimming protozoa and para-
sitic worms. However, chlorine is relatively ineffectual
against their ova and cysts that are resistant to oxidation.
Chlorine has the further advantage of persistence given a
185
-------
TABLE 77 . PROBABLE REACTION PRODUCTS OF
CHLORINE AND SOME TYPICAL ORGANIC COMPOUNDS
FOUND IN POLLUTED WATER SUPPLIES (332 )
Organic Compound
Probable Reaction Products
Alcohols
Methanol
Isopropanol
tert-Batanol
Ketones
Acetone
Benzene and Derivatives
Benzene
Toluene
Ethyl benzene
Benzole acid
Phenol and Phenoli cs
Phenol
m-Cresol
Hydroquinone
Organic Nitrogen Compounds
Aniline
Dimethyl ami ne
Nitrobenzene
None
None
None
None
None
None
None
None
Mono-, di-, and trichlorophenols;
non-aromatic oxidation products
Mono-, di-, and trichlorocresols;
non-aromatic oxidation products
p-Benzoquinone, non-aromatic
oxidation products
Mono-, di-, and trichloroani1ines;
non-aromatic oxidation products
N-Chlorodimethylamine, oxidation
products
None
186
-------
TABLE 78. VIRICIDAL EFFICIENCY OF
FREE CHLORINE IN WATER (136)
Investigator
Chang et al.
Neefe et al.
Lensen et al.
Clarke and
Kabler
Weidenkopf
Kelly and
Sanderson
Virus
Part, purif.
Theiler's
virus in
tap water
Feces-borne
Inf. Hepat.
virus in
dist. water
Purif.
Polio II in
dist. and
lake water
Purif.
Coxsackie
A2 in
demand- free
water
Purif.
Polio I
(Ma honey)
in demand-
free water
Purif.
Polio I
(Ma honey)
in demand-
free water
Purif.
Polio III
(Saukett)
in demand -
free water
Temp.
°C
25-27
25-27
Room
19-25
3-6
3-6
3-6
3-6
3-6
3-6
27-29
27-29
27-29
27-29
27-29
0
0
0
0
0
0
0
25-28
25-28
25-28
25-28
Final
PH
6.5-7.0
6.5-7.0
6.7-6.8
7.4-7.9
6.9-7.1
6.8-7.1
6.9-7.1
8.8-9.0
8.8-9.0
8.8-9.0
6.9-7.1
6.9-7.1
8.8-9.0
8.8-9.0
8.8-9.0
6.0
6.0
7.0
7.0
8.5
8.5
8.5
7.0
9.0
7.0
9.0
Free Chlo-
rine
mg per £
4.0-6.0
4.0-6.0
3.25
1.0-1.5
0.58-0.62
1.9-2.2
3.8-4.2
1.9-2.0
3.7-4.3
7.4-8.3
0.16-0.18
0.44-0.58
0.10-0.18
0.27-0.32
0.92-1.0
0.39
0.80
0.23
0.53
0.53
1.95
5.00
0.21-0.30
0.21-0.30
0.11-0.20
0.11-0.20
Virus Destruction
98.6% in 10 min
99% in 5 min
30 min cont. time
protected all of 12
volunteers
10 min cont. time
protected all of 164
inoc". mice
99.6% in 10 min
99.6% in 4 min
99.6% in 2h min
99.6% in 24 min
99.6% in 9 min
99.6% in 5 min
99.6% in 4 min
99.6% in 3 min
99.6% in 10 min
99.6% in 7 min
99.6% in 3 min
99.6% in 3% min
99.6% in l*s min
99.6% in 8 min
99.6% in 4*s min
99.6% in 16 min
99.6% in lh min
99.6% in 3 min
99.9% in 3 min
99.9% in 8 min
99.9% in 2 min
99.9% in 16 min
187
-------
TABLE 78 (continued)
Free
Investigator
Kelly and
Sanderson
(cont'd)
Clarke et al .
Virus
Purif.
Coxsackie
B5 in
demand-free
water
Purif.
Adenovirus
3 in BOD
demand-free
water
Temp.
°C
25-28
25-28
1-5
1-5
25
25
4
4
7
9
7
8
8
6
8
6
Final
pH
.0
.0
.0
.0
.8-9.0
.9-7.1
.8-9.0
.9-7.1
Chlo-
rine
0
0
0
0
0
0
0
0
mg
.21
per £
-0.30
.21-0.30
.21
.21
.20
.20
.20
.20
-0.30
-0.30
Virus
99
99
99
99
99
99
99
99
.9%
.9%
.9%
.9%
.8%
.8%
o
-------
sufficiently large dose, a low residual chlorine concentration
will remain in the water after treatment, providing continued
disinfectant action. This prevents regrowth and protects against
accidental contamination during distribution.
Despite chlorine's widespread use and some reports of
effective virus kill, other reports are less optimistic about its
performance against virus. Clarke et al. (129) and Sobsey (600)
reported the isolation of viruses in chlorinated drinking water
in Paris (1 pfu/300£) and South Africa (1 pfu/10-fc). In view of
the fact that only one to two viruses of some types are suffi-
cient to cause infection, anything less than 100 percent inacti-
vation may be unacceptable. But with chlorine, even the absence
of any "living" viruses still may not be acceptable. McClanahan
(429) reported that chlorine removes the protein coat of a
virus - thus rendering the virus technically nonviable - but may
leave the infectious nucleic acid core intact. Consequently, a
water supply free of any living viruses may still be infectious.
Ozone is equally as effective as chlorine against bacteria
and viruses and has a much faster reaction rate. Once the
proper "threshold" ozone dose is applied (usually less than
5 mg/£), the bactericidal action is almost instantaneous. Tests
have shown ozone to be between 600 and 3,000 times more rapid
than chlorine in its destruction of bacteria (429). McClanahan
(429) was unable to recover viable nucleic acids from ozonated
water, suggesting that virus destruction was complete, as opposed
to the action of chlorine. Venosa (660) reported that protozoal
cysts resistant to chlorine were easily inactivated by ozone.
Furthermore, the biocidal character of ozone is not affected by
pH, as is the biocidal character of chlorine.
Ozone is not without problems; however, ozone leaves no
residual. It has a fairly short half-life in water and rapidly
loses all disinfectant ability. Experience in Europe has
revealed few problems along these lines, but the added margin
of safety with chlorine has worked against the adoption of
ozone in the United States. The versatility of ozone and its
relatively greater disinfecting ability has led to the suggestion
that initial ozonation could be followed by low-level chlorina-
tion to provide a residual. However, little research has been
conducted along these lines.
Murphy (469) and Vajdic (656 ) both reported that gamma
radiation was as good a disinfectant as chlorine against
bacteria and was somewhat better against the more chlorine-
resistant biologicals. Ultraviolet is a proven bactericide,
but research on other biocidal characteristics has been limited.
Nevertheless, any radiation treatment suffers from operational
difficulties, and, like ozone, provides no residuals.
189
-------
The sanitation districts of Los Angeles County are in the
final stages of an extensive study for EPA and the California
State Water Resources Board. This study titled "The Pomona
Virus Study," has evaluated virus removals by various combina-
tions of tertiary treatment processes and followed by chlori-
nation or ozonation. Their conclusions in part are that the
majority of virus inactivation occurs during disinfection and
the main function of the preceeding tertiary unit processes
was that of removing substances (turbidity, organics, etc.)
which interfere with efficient disinfection. In virus seeding
experiments involving combined chlorine residuals of 5 mg/s,
average seed virus removals of 4.7 to 5.1 logs were achieved.
With 10 mg/£ of combined chlorine residuals,5.2 logs of virus
removal were achieved. In seeding experiments involving ozona-
tion, average log virus removals ranged from 5.1 to 5.4 logs.
190
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SECTION 10
ADVANCED WATER TREATMENT: ADSORPTION ONTO
ACTIVATED CARBON AND OTHER MATERIALS
INTRODUCTION
Activated carbon adsorption (or simply carbon adsorption)
is employed to remove color, odor, taste, and refractory organic
compounds from water. Many water treatment plants presently pass
their effluent through a carbon column or fine-grain carbon bed
to polish the final product. Available data indicate that carbon
adsorption is an effective method for removing synthetic and
natural organic contaminants, particularly chlorinated hydro-
carbons and organophosphorus pesticides, from water. Carbon
adsorption may also be used to remove some metals. There is some
adsorption of the free metal, but metal removal can be greatly
enhanced by the addition of an organic chelating agent prior to
passage through the carbon. The carbon will readily adsorb the
chelating agent, thereby also removing the complexed metal.
The literature that has been reviewed on the effective-
ness of the adsorption process in potable water treatment is
summarized in Table 79. The major portion of the research
to date has involved tertiary wastewater treatment application,
although there has been substantial work also in the water
treatment field as shown in Table 79. With the recent
concern over residual organics in U.S. water supplies, one
can anticipate increased activity in both pilot and full-
scale activated carbon systems for treating water supplies.
In addition to activated carbon, synthetic polymeric adsor-
bents have been extensively tested and show promise for
potable water treatment. They are not widely used in water
treatment plants but have been tested in pilot-scale instal-
lations. Some tests have indicated higher removal efficiencies
for synthetic adsorbents than for activated carbon for some
contaminants. Inorganic adsorbents, such as clays and
magnetite, are also capable of contaminant removal.
WATER QUALITY PARAMETERS
Activated carbon adsorption was used following chemical
coagulation and rapid sand filtration at the much-publicized
Windhoek, South Africa, water treatment plant. The influent
191
-------
TABLE 79. LITERATURE REVIEWED PERTAINING TO ADSORPTION
Contaminant Reference Number
Water Quality Parameters
Ammonia 442, 610
BOD 515, 610
COD 515
Chlorides 442, 551, 589
Nitrates 442, 610
Nitrites 610
Oil and grease 316
Phosphates 515
Sulfates 610
Sulfides 378
Suspended solids 515
Taste and odors 70, 157, 276, 282, 316, 378, 442, 524
Turbidity 70, 276, 442
Elemental Contaminants
Arsenic 467, 506
Barium 506
Cadmium 467
Chromium 506
Iron 442
Lead 467
Mercury 157, 309, 394, 467, 506, 640, 641
Selenium 506
192
-------
TABLE 79 (continued)
Contaminant Reference Number
Elemental Contaminants
Silica 126
Biocidal Contaminants
DDT 157, 192, 537, 546, 589
DDE 192
Aldrin 157, 192, 537
Dieldrin 157, 192, 316, 537, 546
Endrin 157, 192, 537, 546
Carbamates 193
Chlorinated
hydrocarbons 157, 192, 316, 537, 551, 589
Organophos 157, 192, 467, 537
Herbicides 157, 467
Lindane 546
Other (general) 157, 262, 546, 570
157, 262, 276, 284, 316, 352, 442,
455, 467, 506, 537, 589, 610, 632
Biological Contaminants
Polio virus 467
Virus 467, 498
193
-------
to this plant was treated wastewater which was subsequently
mixed with surface water for direct reuse. Stander and
Funke (610) reported on the effluent quality through the
pilot plant. The concentration of ammonia nitrogen in the
effluent was lowered from 0.3 to 0.1 mg/l by passage through
an activated carbon filter. ABS and BOD were also signi-
ficantly reduced, 82 and 67 percent, respectively.
Table 80 , from Medlar (442), summarizes water quality
analysis data from several water treatment plants in New
England employing granular activated carbon filters. Two
of these plants (Amesbury and Scituate) use carbon for both
filtration and adsorption, while the remaining four use
carbon for adsorption only. At each plant, the carbon signi-
ficantly reduced ammonia levels, as between 33 and 100 percent
of the influent ammonia was removed.
Phillips and Shell (515) presented a study of the
effectiveness of granular activated carbon and other general
contaminants in removing BOD. The study was conducted at a
pilot water plant treating wastewater effluent by chemical
coagulation, filtration, and passage through 16-ft carbon
columns. Data are presented in Table 81 . BOD removal by
the carbon columns averaged 33 percent, while COD was
reduced 80 percent.
TABLE 81. ACTIVATED CARBON FILTRATION AT
COLORADO SPRINGS PILOT PLANT (515)
Influent Effluent Removal
BOD5
COD
SS
P04
ABS
(ma/£
3
41
4
2
0.9
)
2
8
3
1
0.03
m
33
80
25
50
97
Activated carbon is highly efficient for removing non-
colloidal, soluble, aromatic-structured color sources.
David Volkert and Associates (157) indicated that
the carbon removal efficiency for color-producing substances
is 100 percent of methylene-blue active substances. Table 80
shows that the color removal efficiency of carbon filters
in six water treatment plants was nearly 100 percent
(Medlar, 442). Activated carbon has also been
used industrially for decolorizing organic dye waste effluents
194
-------
TABLE 80. SUMMARY OF WATER QUALITY ANALYSIS DATA
FROM ACTIVATED GRANULAR CARBON (442)
VO
CJl
Color (APHA): Raw
Finished
Turbidity (N.T.U.): Raw
Finished
Iron (mg/£): Raw
Unfinished
Odor ( ton) : Raw
Unfinished
Specific Conductance
(ymhos/cm) : Raw
Unfinished
Nitrate (mg/t): Raw
Unfinished
Ammonia (mg/£): Raw
Unfinished
Silica (mg/l): Raw
Unfinished
Ames bury
Mass.
115
0
14.5
0.2
3.5
0.03
3
0
155
230
0.0
0.0
0.7
0.0
11.0
9.6
Newburyport
Mass.
50
0
2
0
0.25
0.16
2
0
102
280
0.0
0.5
.02
.01
4.6
5.4
Scituate
Mass.
250
5
4
0.12
1.57
0.05
3
0
150
268
0.2
0.2
0.22
0.13
7.7
8.3
Somerset
Mass.
30
2
K8
.13
.35
.05
1
0
76
107
0,1
0.2
.07
.02
,7
.8
Manchester
N.H.
20
0
1
0
0.4
trace
1
0
__
Burlington
Mass.
34
0
1.0
0,2
0.51
0,10
3
0
190
235
0,4
0.4
0.21
0,14
-------
Recently, the nonionic polymeric adsorbents, such as Amberlite
XAD-7, have been gaining popularity for this purpose (589).
While Table 80 and the operation at Windhoek (610)
show that both organic and ammonia nitrogen were reduced by
carbon adsorption, they also show that oxides of nitrogen
(nitrate and nitrite) were not reduced.
Oils derived from natural, domestic, or industrial sources
may occasionally be found in wastewater effluents and in water
supplies. Hyndshaw (316) reported that petroleum products
are very quickly adsorbed from water by activated carbon.
He stated that for emergencies, such as gasoline or oil
spills, large quantities of powdered activated carbon will
remove the hydrocarbons.
Reduction of phosphates as P04 from 2 mg/l in the carbon
filter influent to an effluent concentration of 1 mg/£ is shown
in Table 81 (515). Sulfate as S04 was not reduced from its
concentration of 220 mg/l by carbon filtration at the Windhoek
plant. However, sulfides in the form of hydrogen sulfide,
and polysulfides that result from the reaction of chlorine
with hydrogen sulfide were removed from well water, according
to Lee (378). The removal was indirectly evidenced by the
destruction of sulfide odor in the water supply and resulted
from a catalytic reaction with the carbon rather than from
adsorption.
Activated carbon is commonly used for removing tastes
and odors from water. Undesirable odors in water are caused
by the vapors from many chemicals, including halogens,
sulfides, ammonia, turpentine, phenols and cresols, picrates,
and various hydrocarbons and unsaturated organic compounds,
some of which have not been identified. Tastes and odors
are also caused by substances produced by living microorganisms
or decaying organic matter. Some inorganic substances, such
as metal ions in high concentrations (especially iron)
also impart taste and odor to water. Removal of many tastes
and odors with activated carbon approaches 100 percent.
Successful taste and odor removal from a municipal water
supply by carbon bed filters was demonstrated in Buckingham,
England (Hager, 276). The water was taken from a river
that runs through farmland and had an earthy taste that
resisted chlorination; clarification and sand filtration; and
experimentation with ozone, permanganate, and chlorine
At Goleta, California, taste and odor in the water supply
were also eliminated by passage through granular activated
carbon beds (276). Popalisky and Pogge (524) reported that
powdered activated carbon was used at a water plant treating
Missouri River water to eliminate taste and odor caused by
microorganic compounds. The compounds and their concentrations
were not identified.
196
-------
Hansen (282) reported that installation of granular carbon
filters at Mount Clemens, Michigan, completely removed the septic
and phenol tastes and odors that were present in the Clinton
River water supply during runoff periods. Granite City, Illinois,
reported a similar experience (70). The dosage of activated
carbon required to remove taste and odor is influenced by chlorine
application. Generally, carbon should be applied before chlo-
r i n a t i o n (316).
Many pesticides and herbicides produce tastes and odors
when present only in very small concentrations in water.
Hyndshaw (316) used the beta isomer of benzene hexachloride
to illustrate the influence of a small concentration of a
biocide on the taste and odor quality of water. This substance,
when present in amounts as little as 17 ppb in odor-free water,
gives a threshold odor number (TON) of 8. (The threshold
number denotes the number of volumes of odor-free water
required to dilute the odor concentration to a point where
the odor is just barely perceptible.) Other organic pesticides
and their concentrations and subsequent effects upon taste
and odor are shown in Table 82 (316).
TABLE 82. ODOR IMPARTED TO ODOR-FREE WATER
BY PESTICIDES AND HERBICIDES (316)
Substance
Toxaphene
2,4 D (isoctyl)
2,2 D
D-D
Rothane
Chi ordane
BHC
Concentration
ppm
0.84
2.0
92.5
0.0235
50.0
0.07
0.0175
Odor
TON
6
17
4
17
Nil
140
8
A simple study employing the threshold odor test gave
evidence of the reduction of these compounds by activated
carbon. The amount of activated carbon required to reduce the
odor of each compound to a palatable level is presented in
Table 83 (316).
197
-------
TABLE 83. ACTIVATED CARBON REQUIRED TO REDUCE
ODORS CAUSED BY PESTICIDES AND HERBICIDES
TO PALATABLE LEVELS (316)
Substance
Parathion
37 gamma BHC
Malathion
2,4 D
DDT
Concentration
of substance
PDm
10
25
2
6
5
Odor
TON
50
70
50
50
70
Carbon
Dosage
PPm
20
15
20
40
4
Odor
after Carbon
TON
4
1 .4
4
3
3
Significant reduction in turbidity and suspended solids
concentration is also effected with activated carbon. The
data in Table 80 show that turbidity is
reduced both at plants where granular activated carbon is
used for filtration and adsorption and where it is used for
adsorption only. Passage of water through 16-ft carbon
columns effected 25 percent removal of suspended solids at
Colorado Springs (Table 81) (515).
Turbidity removal is essentially complete at Nitro,
West Virginia, where activated carbon has replaced sand in
the filters (276). Final effluent JTU's are typically less
than 0.1. At Granite City, Illinois, Blanck and Sulick ( 70)
report that suspended solids removal by carbon filtration
exceeds that achieved with sand filters.
ELEMENTAL CONTAMINANTS
Although little data from municipal water purification
applications are available, it appears that activated carbon
can provide some removal of heavy metals. Direct adsorption
provides some removal, but efficiencies can be increased to
nearly 100 percent by adding an organic chelatlng agent
(537). The carbon removes the complex by adsorbing the organic
agent, removing the metal along with it.
Patterson (506) cited evidence that filtration of water
containing 0.2 mg/£ arsenic through a charcoal bed yielded
an effluent containing 0.06 mg/l of arsenic, or 70 percent
removal. He cited another report of 40 percent reduction of
arsenite by activated carbon from an initial concentration of
0.5 mg/l to a concentration of 0.3 mg/£. Morton and Sawyer
(467) tested heavy metal adsorption during filtration
through a granular bed of attapulgite clay. Data are presented
198
-------
in Table 84 that show the amounts of metals remaining in the
effluent after filtration of various quantities of water at
two different rates. The initial solutions contained 1 mg/£
of each metal. Arsenic was reduced from 0.97 and 0.98 mg/£ to
0.02 and 0.03 mg/£ upon filtration of 2.5 volumes of water
per volume of bed.
TABLE 84 . REMOVAL OF HEAVY METALS BY PERCOLATION WITH
GRANULAR LOW VOLATILE MATTER ATTAPULGITE CLAY (467)
Rat
io o
Percola
Vol ume
Initial
2.
5.
10.
f Volume
te to
Bed
Recoveries
in
Effluent
Concentration 0.
5 0.
0 0.
8 0.
As
97
02
12
56
1
0
0
0
Cd
.00
.01
.01
.01
(
Slow
1
0
0
0
Pb
ppm)
Rate*
.06
.01
.01
.01
1
0
0
0
Hg
.11
.004
.01
.11
6
6
* 960 gal/ton clay/hour.
f 2,880 gal/ton clay/hour
Fast Rate"1"
Initial Concentration
2.5
5.0
12.6
0.98
0.03
0.16
0.68
1 .00
0.01
0.01
0.01
1 .06
0.01
0.01
0.01
1 .11
0.010
0.072
0.152
In a study cited by Patterson (506), carbon adsorption
did not improve barium removal efficiency over that achieved
with chemical coagulation and clarification. Patterson notes
that others have also found poor removal efficiency for barium.
presented in Table
and was unaffected
84 (467)
by the
Cadmium removal data are also
Removal of 99 percent was achieved
changes in flow volume and rate.
Some success has been reported from pilot plant work on
chromate removal by activated carbon. Patterson (506)
reported on a study of metal removal from municipal wastewater
plant effluent, in which initial hexavalent chromium levels
of 0.09 to 0.19 mg/£ were reduced to 0.04 mg/£ or less. The
average effluent concentration reported was 0.017 mg/£.
199
-------
Initial hexavalent chromium levels of 5 mg/£ were reduced to
0.09 mg/£ following carbon adsorption. Patterson noted that
it appears that activated carbon may not be equally effec-
tive at higher chromate levels.
Table 80 reports removal of iron at six water treatment
plants by granular activated carbon filtration. Removal effi-
ciencies ranged from 99 percent to 36 percent.
Lead removal is shown in Table 84 for adsorption onto
attapulgite clay. Over 99 percent removal was achieved at
all flow volumes and rates tested.
Mercury adsorption has been studied extensively. In
Table 84 , it is shown that adsorption onto attapulgite clay
of over 99 percent was achieved after filtration of 2.5
volumes of water per volume of bed. Removals decreased to
86 percent removal as 12.6 volumes per volume of bed were
filtered. Logsdon and Symons (394) conducted jar tests
using powdered activated carbon. Increasing carbon dosages
increased removal of both inorganic and organic (methyl)
mercury. Organic mercury removal was more efficient than inorganic
mercury removal for a given dosage of powdered activated
carbon at effluent concentrations less than 2 ppb. Residual
concentrations of 0.8 ppb of inorganic and 0.2 ppb of methyl
mercury were achieved. Further tests were performed in
which powdered carbon was added just before alum coagulation
to improve mercury removal. Removal by alum alone was about
40 percent, whereas removal with 65 mg/l of activated carbon
plus 30 mg/£ of alum was in excess of 70 percent with an ini-
tial mercury concentration of 9.3 ppb.
The capacity of granular activated carbon for removing
mercury from water was also evaluated by pumping mercury
solutions through columns (394). Average influent concentra-
tions ranged from 20 to 29 ppb. Mercury removals declined
as the number of bed volumes (based on gross void space) of
water treated increased. Columns with 3.5-min contact times
removed 80 percent of the inorganic mercury for up to 15,000
bed volumes of water and 80 percent of the methyl mercury for
up to 25,000 bed volumes treated. Evaluation of carbon column
performance at 80 percent removal indicated that as contact
time in the column increased, the amount of mercury adsorbed
by the carbon increased. Also, granular activated carbon
adsorbed more methyl mercury than it did inorganic mercury per
gram of adsorbent. This behavior was expected, since acti-
vated carbon has a high capacity to adsorb organics.
Thiem (640) also conducted jar tests on mercury adsorp-
tion using powdered activated carbon. Solutions containing
10 ppb mercury were brought into equilibrium with various
carbon dosages. Less than 30 percent of the mercury was
200
-------
adsorbed at a carbon dosage of 10 mg/l at pH 7. When 100
mg/£ of carbon was applied to the test solution, removal
approached 80 percent. Removal decreased with increasing
pH, with best removal occurring at pH 7. The addition of
chelating agents such as EDTA or tannic acid prior to contact
with the carbon increased adsorption. Concentrations of as
little as 0.02 mg/£ of EDTA or 1 mg/l of tannic acid increased
removals from 10 to 30 percent, depending upon the carbon
dosage that was applied and the pH of the system.
Patterson (506) summarized the data on activated carbon
removal of mercury, saying that the highest percentage removals
(80 to 95 percent) are achieved with more concentrated mercury
solutions. However, lowest effluent mercury results from
treatment of less concentrated waters, although the relative
efficiency is less. Thus carbon treatment of initial mercury
below 1 ppb yields an efficiency of removal of less than
70 percent, but effluent mercury is below 0.25 ppb. Carbon treat-
ment of initial mercury concentrations of 5 to 10 ppb yields
about 80 percent removal and effluent levels of below 2
ppb. Carbon treatment of initial mercury concentrations
between 10 and 100 ppb yields 90 percent or greater effi-
ciency.
Poor selenium removal from well water by activated carbon
has been reported in one case cited by Patterson (506).
Removal was less than 4 percent. Poor or no reduction of
silica has also been shown by the data from six operating water
purification plants employing carbon adsorption and filtra-
tion (442).
BIOCIDAL CONTAMINANTS
As with other synthetic-organic compounds, some of the
organic pesticides and herbici'des that are resistant to removal
by conventional treatment techniques are effectively removed
by adsorption. David Volkert and Associates (157)
cited evidence that over 99 percent of the following chlorinated
hydrocarbons can be adsorbed by activated carbon:
DDT
Aldrin
D i e 1 d r i n
Endrin
Chlordane
Heptaclor epoxide
Lindane
Methoxychlor
Toxaphene
201
-------
Laboratory studies cited by Stone (537) have shown that
the following reductions in chlorinated hydrocarbon concen-
trations can be achieved by contacting with appropriate
doses of activated carbon (Table 85):
TABLE 85. ACTIVATED CARBON REMOVALS OF CHLORINATED
HYDROCARBONS ACHIEVED IN LABORATORY EXPERIMENTS (537)
Substance
Chi orinated
hydrocarbons
DDT
DDT
A 1 d r i n
A 1 d r i n
Aldrin
D i e 1 d r i n
Die! dri n
Dieldri n
Endri n
Endrin
Chlordane
Li ndane
Li ndane
Li ndane
Initial
Concentration
6.3
5
5
6.6
5
-
-
0.5-1
4.4.
5
0.5-1
50
10
25
1
ppb
ppm
ppm
ppb
ppm
t
0 ppb
ppb
ppm
0 ppb
ppm
ppb
ppb
ppb
Treated
Concentration
0.04-0.11 ppb
-
-
-
-
-
-
0.25 ppb
-
-
0.25 ppb
-
1 ppb
-
0.05 ppb
Percent
Reduction
98-99
90
76
90
85
99
99
50-97
99
86
50-97
99
90
90
95
Activated carbon removals of several pesticides are well
illustrated by results of laboratory studies cited by the
California State Water Resources Control Board (615)
shown in Table 86 .
TABLE
Carbon
Dosaae (ma/£)
Control
1.0
2.0
2.5
5.0
10.0
12.5
25.0
50.0
86.
REMOVAL
CARBON
Aldrin
48
26
15
12
6
4
.3
.4
Endri
62
15
3
1
0
0
OF SPECIF
ADSORPTION
Re si
n Dieldrin
.4
.5
.56
.22
19
6.3
2.4
1.1
1C TOXIC
( 615)
dual
DDT
41
41
21
3.
MATER
IALS
(ppb)
ODD DDE
7
56
6.
3.
2.
0.
0.
9
7
2
45
35
38
34
29
12
3.
1.
0.
BY
Toxaphene
155
147
80
31
2.7
3
1
9
202
-------
Adsorption of the carbamate pesticides Sevin and Baygon
on granular activated carbon was investigated by El-Dib et al.
(193). Passage of a 5 mg/£ solution of Baygon through carbon
columns effected complete removal for up to 273 bed volumes
of water when a contact time of 3.76 min was allowed. In
the case of Sevin, 1,800 bed volumes were passed with complete
removal under the same conditions. Rapid breakthrough of
the pesticides into the effluent occurred, however, as the
contact times were decreased to 1 or 0.5 min.
According to reference 570, the available data on
organophosphorus pesticide removal indicates that the effi-
ciency of activated carbon ranges from 50 to over 99 percent.
Stone and Company (537) cited laboratory-scale tests showing that Para-
thion was reduced from 10 to 2.5 mgA using 20 mg/£ powdered
carbon; and from 11.4 to 0.05 mg/£ using dual granulated carbon
filters. Malathion was reduced in laboratory-scale tests
from 2 to 0.25 mg/Ji with 10 mg/2 powdered carbon. Some data
on removal efficiencies of the organic herbicides were also
cited. They report that over 99 percent removal of 2,4-5-T and
2,4-D is possible.
Robeck et al, (546) surveyed the effectiveness of various water
treatment processes in pesticide removal. Table 87 summarizes
their results using carbon in both a slurry form and in beds.
TABLE 87 . SUMMARY OF CUMULATIVE PESTICIDE
REMOVAL AT 10-ppb LOAD (546)
Process
Pesticide Removed - Percent
DDT Lindane Parathion Dieldrin
2,4,5-T
Ester
Endrin
Carbon:
SIurry
5 ppm 30
10 ppm 55
20 ppm 80
Bed 0.5 gpm/
cu ft > 99 > 99
> 99
> 99
> 99
> 99
75
85
92
99
80
90
95
> 99
84
90
94
In addition to activated carbon, other adsorbents such
as clays and synthetic polymeric adsorbents are capable of
removing biocidal contaminants. Morton and Sawyer (467) studied
the adsorption of diazinon, an organophosphorus pesticide,
onto attapulgite clay. Coarse-ground, high-volatile matter
attapulgite was stirred with contaminated water in laboratory
experiments. At least 50 percent of the diazinon in a 0.1
mg/£ solution was removed by the clay in a 10 percent clay
suspension. An investigation of the use of the synthetic
polymer Amberlite XAD-4 for the removal of various pesticides
203
-------
was cited by Stone and Company (537). The pesticides examined
included lindane, B-BHC, aldrin, and dieldrin in tap water at
initial concentrations of 1 ppb each. Consistent removals of
over 60 percent were reported.
Schwartz (570) also studied the adsorption of selected
pesticides on activated carbon and mineral surfaces. He found
that the clay minerals ilite, kaolinite, and montmori1lonite
suspended in dilute pesticide solutions adsorbed very little
2,4-D or isopropyl N-(3-chlorophenyl) carbamate (CIPC).
Adsorption of CIPC from aqueous solution with powdered activated
carbon, however, was extensive (>90 percent).
SYNTHETIC/ORGANIC CONTAMINANTS
Adsorption is commonly cited as a presently available
technology for removing particulate, colloidal, and soluble
organic contaminants from water. Many of the organics pre-
sent in water supplies - particularly the soluble and colloidal
organics - are of a refractory nature, i.e., they resist removal
by conventional methods. A number of these are potentially
toxic or carcinogenic and, as a result, their detection, iden-
tification, and treatment in water is receiving increasing
attention. These substances, even in small amounts, contri-
bute to taste and odor conditions and may pose a chronic
health hazard. As has been discussed, activated carbon is
widely applied for taste and odor removal; however, its
effectiveness for removing residual organics has just come
under study in recent years. The delay has been caused in
part by the lack of standard procedures for identifying and
classifying the vast assortment of organics that occurs in
trace quantities in water (262,455). The delay is also due
to the search for a gross organic parameter that can be used
as a measure of organics. The more common parameters used
include carbon chloroform extract (CCE), liquid extraction,
paper and gas chromatography, fluorescent spectroscopy, and
radiation.
Traditionally, carbon life expectancy has been based on
the capability of the carbon to absorb tastes and odors.
But research has shown that the life expectancy of carbon
to reduce carbon chloroform extract or organic compounds is
somewhat less than that to remove tastes and odors (442).
Medlar (442) suggested that monitoring carbon chloroform
extract concentration in carbon filtered water would
provide a conservative estimate of filter performance, but noted
that the CCE test may not encompass all the compounds that
should be considered.
Carbon chloroform extract indicates the presence of stable
organic compounds in water. The extract has an operational
definition and is a mixture of organic compounds that can be
204
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adsorbed onto activated carbon and then desorbed with organic
solvents under specific controls. Examples of substances mea-
sured with this method include substituted benzene compounds,
kerosene, polycyclic hydrocarbons, phenylether, and insec-
ticides. The efficiency of activated carbon in reducing CCE
depends upon several factors including water temperature, ini-
tial amount of contaminant, and the molecular weight of the
contaminant (157). Percentage removals must therefore be deter-
mined by laboratory testing. Removals ranging from 50 to 99
percent were reported by David Volkert and Associates
(157).
The adsorption of polycyclic (polynuclear) aromatic
hydrocarbons (PAH) from water by activated carbon was discussed
by Harrison et al. (284). These compounds are potential
carcinogens under certain conditions. Carbon adsorption has
been shown to give 99 percent removal of PAH from water filtered
by prior seepage through river bank soil.
Bis-ethers are synthetic organic compounds that may
occur in water associated with industrial discharges. Stone and
Company (537) cited laboratory tests of activated carbon treatment
in which isopropyl ether concentrations were reduced from
1,023 to 20 mg/£, butyl ether concentrations from 197 mq/i
to nil, and dichloroisopropyl ether concentrations from
1 ,008 mg/x, to nil.
The treatment of dilute phenolic industrial wastewater
was reviewed by Patterson (506). Adsorption onto activated car-
bon has been employed to remove over 99 percent of the phenol
present in process waters with initial concentrations ranging
from 5,325 mg/a to 0.12 mg/£. Final phenol concentrations
ranged from 0.25 mg/£ for treatment of a concentrated solu-
tion to 0.001 mg/£ for treatment of weaker solutions.
Foaming agents such as linear alkyl benzene sul-
fonate in concentrations up to 5 mg/a can be removed by acti-
vated carbon with 90 to 100 percent efficiency according to
evidence cited by David Volkert and Associates
(157). Table 81 (Phillips and Shell, 515), which presents
data on activated carbon filtration at the Colorado Springs
pilot plant, shows 97 percent removal of alkyl benzene sul-
fonate (ABS). Stander and Funke (610) reported reduction of
ABS from 4 to 0.7 mg/a at the Windhoek pilot plant. Organic
acids are also reported to have been reduced from 1 to 0.4 mg/£.
Morton and Sawyer (467) studied the adsorption of two
organic compounds - diethylsti1bestrol (DES), which is a hormone
and aflatoxin, which is a natural toxin produced by fungi -
onto attapulgite clay. Attapulgite is a magnesium aluminum
silicate clay that exhibits a high degree of adsorption for
205
-------
low-weight organic molecules. Coarse-ground, high-volatile-
matter attapulgite was contacted with contaminated water in
laboratory experiments. DES at a concentration of 5 ppb was
decreased 68 and 76 percent by contacting with 1.1 and 10
percent (fay weight) clay suspensions, while in a 50 ppb
solution the removals were 68 and 89 percent, respectively.
More than 98 percent of the aflatoxin at concentrations of
0.5 ppb and 5.0 ppb was removed by both 1.1 and 10 percent
clay suspensions. The results of column percolation studies
through granular low-volatile-matter clay are presented in
Table 88.
TABLE 88. REMOVAL OF ORGANICS BY PERCOLATION
WITH GRANULAR, LVM ATTAPULGITE
Ratio of percolate Recoveries in Effluent
volume to bed volume Slow rate* Fast rate1"
Initial Concentration
2.5
5.0
10.8
12.6
52 ppb
ND}
ND
ND
48 ppb
ND
1
2
Initial Concentration 17 ppb 17 ppb
2.5 ND ND
5.0 ND ND
10.8 ND
12.6 -- ND
* 960 gal/ton clay/hour.
t 2,880 gal/ton clay/hour.
£ ND = not detectable.
Stone and Company (537) cited data concerning the treatment
of polychlorinated biphenyls (PCB's) by adsorption onto clay
minerals and Amberlite polymeric adsorbents. In laboratory
tests, Amberlite XAD-4 removed up to 76 percent of the PCB
present in solutions. Several clay minerals demonstrated PCB
removal capability in laboratory tests: illite - 60 percent,
montmorillonite - 40 percent, and kaolinite - 40 percent.
Kinoshita and Sunata (352) evaluated the adsorption of PCB onto
powdered activated carbon in a jar test and found that the
initial concentration of 100 ppb PCB was reduced to 10 ppb in the
product water.
206
-------
The Amber-lite adsorbents represent a new technology for
adsorbing organic molecules from water. They are used spe-
cifically for adsorbing aromatic and aliphatic compounds.
According to Simpson (589), small molecules such as phenol
are effectively adsorbed by Amberlite XAD-4, while for a
larger molecule such as an alkylbenzene sulfonate, Amberlite
XAD-2 has a much higher adsorptive capacity. Phenol is a
model aromatic, low-molecular weight compound that is con-
sidered to be highly objectionable, as are some of the chlori-
nated phenol products. Using the XAD-4 adsorbent, up to 40
bed volumes of a 500 ppm water solution of phenol were treated
with less than 10 percent leakage at a flow rate of 0.5 gal/fW
min. At a higher flow rate of 2.0 gal/ft3/min, 20 bed volumes
were treated with less than 10 percent leakage. It was further
found that the adsorptive capacity was higher for chlorinated
phenols than for simple phenol. Simpson (589) cited a labora-
tory study in which the removal efficiency of Amberlite XAD-2
for a list of organics at flow rates of 1.25 gpm/cu ft were
determined. The results are presented in Table 89. Non-
ionic compounds were removed with 100 percent efficiency while
ionized compounds were less effectively removed.
In the nationwide study of water supplies and water treat-
ment facilities by Symons et al. (632)> it was concluded that
both powdered and granular activated carbon treatment signi-
ficantly reduced the trace concentrations of total trihalo-
methane in the product water.
TABLE 89.* ADSORPTION OF ORGANIC COMPOUNDS ONTO
AMBERLITE XAD-2 POLYMERIC ADSORBENT (589)
Retention
1. Aliphatics Influent Effluent Efficiency, %
a) alcohol: n hexanol 200 ppm 30 ppm 85
b) ester: ethyl butyrate 100 0 100
c) ketone: methylisobutylketone 100 0 100
2. Aromatics
Benzene 100 0 100
Benzene sulfonic acid 3.0 2.1 31
p-toluene sulfonic acid 9.0 6.9 23
Benzoic acid 1.0 0.8 23
Benzoic acid (pH 3.2) 1.0 0 100
Phenol 0.4 0.22 45
Phenol (Amberlite XAD-7) 0.4 0.06 86
0-Cresol 0.3 0 100
2, 4-dimethyl phenol 0.4 0 100
p-nitrophenol 0.2 0 100
2-methylphenol 0.3 0 100
207
-------
TABLE 89. (continued)
2. Aromatics (continued)
Influent Effluent
Retention
Efficiency,
4, 6-dinitro-2-aminophenol
Phenylenediamine
Aniline (Amberlite XAD-7)
Naphthalene
2-hydroxy-3 naphthoic acid
0.4
0.9
4.0
0.05
0.6
0.22
0.02
0
0
0.37
43
98
100
100
39
BIOLOGICAL CONTAMINANTS
The limited efficiency of activated carbon in removing
viruses from wastewater was discussed in the advanced waste-
water treatment section of this report. Results show that
activated carbon is inefficient in removing viruses from
drinking water. Oza and Chaudhuri (498 ) suggested that the
inefficiency may be due to the exclusion of viruses from the
micropores of activated carbon because of their size.
Coal adsorption of a bacterial virus was investigated,
and results indicated that coal may be a more effective
adsorbent than activated carbon. Morton and Sawyer (467 )
demonstrated that attapulgite clay also has the capacity to
adsorb polio virus from water. Aqueous virus-clay suspensions
were shaken for 1 min and then filtered. High-volatile-
matter clay completely removed virus infectivity from a
20 percent clay suspension with an initial virus concentration
of 16 million infectious particles per rru. However, reducing
the contact time from 30 to 5 min or the clay concentration
from 20 to 5 percent resulted in incomplete removal.
208
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ADVANCED WATER TREATMENT: ION EXCHANGE
Ion exchange has its greatest current application in
industrial and small-scale potable water supply operations. The
most common use of ion exchange is for removal of hardness
(calcium and magnesium cations) from municipal, industrial,
household, and laboratory water supplies. It is particularly
suited for desalting brackish water, pretreating water that must
be almost completely demineral iz'ed for industrial use, and
remo.ving metals from industrial metal plating rinse wastewaters.
No one ion exchange resin is capable of removing all ionic
contaminants. Various resins, depending upon their chemical
nature, show preferential selectivity for specific ions.
Table 90 presents data on ion selectivity for various types of
exchange resins (506).
_ TABLE 90. ION EXCHANGE RESINS SELECTIVITY (506) _
_ Resin _ Resin Selectivity* _
Strong-acid cation Li+, H+, Na+, NH4+, K+, Rb+, Cs+,
(Sulfonic) Mg+2, Zn+2, Cu + 2, Ca+2, Pb + 2
Weak-acid cation Na+ K+, Mg+2, Ca+2,
(Carboxylic) Cu+2, H+
Strong-base anion F", OH', ^04-, HC03-, Cl~, N02',
(Type I) HS03-, CM- , Br~ , N03-f HS04-, I~
Strong-base anion F~, H2P04~, OH~,
(Type II) C1-, N02-, HS03-, CN~,
Br~, N03-, HS04~, I-
Weak-base anion F", Cl~, Br", I~, P04-3,
N03-, CrQ4-2, S04-2, OH"
increasing selectivity left to right.
The more strongly a resin adsorbs a particular ion, the
more complete the ion removal. However, a high affinity
between a particular resin and a specific ion also means greater
difficulty in regenerating the resin; that is, it is more
209
-------
difficult to release the adsorbed ions to make the resin reuse-
able. As a result, regeneration of an effective resin is
seldom carried to completion, and the operational capacity of an
ion exchange resin may be reduced to 50 to 60 percent of theoret-
ical ca paci ty.
Ion exchange processes are very sensitive to both clogging
and fouling. An ion exchange resin bed is a good filter;
therefore, suspended solids in water will clog the bed. Fouling
results when the resin adsorbs materials which, because of their
adsorption or absorption into the resin pores, cannot be removed
in the regeneration step. Fouling often results from the
irreversible sorption of high molecular weight organic acids.
The nonselective nature of most exchange resins is a
drawback when attempting to remove a low-level contaminant from
water. The simultaneous removal of other nontarget ions rapidly
increases the cost of using the process. More selective resins
are currently becoming available (Koerts, 359).
In the past, application of ion exchange processes was
confined to the removal of ionic contaminants. Recently,
however, some ion exchangers have been developed that can remove
nonionic species, e.g., A1203, Fep03, H2Si03, etc. Resinous
adsorbents are also available that are particularly suited for
removing organic compounds - including biocidal and synthetic/
organic contaminants - from water. While often used in conjunc-
tion with true ion exchange processes, the mechanism of organic
removal is actually adsorption; therefore, the resinous or
polymeric adsorbents (as they are called) are discussed in the
carbon adsorption section of this report. The literature
utilized during this review on the removal of various contami-
nants by ion exchange methods is indicated in Table 91.
WATER QUALITY PARAMETERS
Reduction of total dissolved solids may be an important
application of the ion exchange process when reclaimed waste-
water for potable reuse is the objective of treatment. High
total dissolved solids concentrations, from 500 to over 1,000
mg/£, are found in wastewaters. Approximately 300 mg/£ of total
dissolved solids is generally considered the increment added
during one cycle of domestic use of a water supply. Ion
exchange treatment of water and wastewater for removal of
dissolved solids is most successful after prior treatment using
both conventional and advanced techniques has taken place. This
prevents clogging and fouling of the exchange resins.
Ion exchange is technically capable of producing a water
with only 0.055 mi cromhos ,(jjmhos) of specific conductance. One
micromho will normally indicate a dissolved solids concentration
of 0.5 to 0.6 mg/£. However, water of such purity is rarely
210
-------
TABLE 91. LITERATURE REVIEWED PERTAINING TO ION EXCHANGE
Contaminant Reference Number
Water Quality
Parameters
Ammonia 101, 505, 506, 524
Chlorides 157, 505, 506, 524
Color 157
Cyanides 157, 506
Fluorides 157, 506
Hardness 505
Nitrates 63, 90, 101, 119, 157, 267, 297
Phosphates 63, 119
Sodium 119, 157, 505
Sulfates 119, 157, 505
Total dissolved 63, 119, 505, 506
solids
Elemental Contaminants
Arsenic 99, 506, 576
Barium 506
Boron 506
Cadmium 506
Chromium 506
Copper 359, 506
Iron 12, 506
Manganese 12, 506
Mercury 359, 506
Nickel 506
211
-------
TABLE 91 (continued)
Contaminant Reference Number
Selenium 506
Zinc 359, 506
212
-------
required, and the costs to achieve such purity would be pro-
hibitive. Complete demineralization of municipal water supplies
is unwarranted and may even have adverse consequences, as the
body requires certain trace concentrations of many mineral's.
The EPA and the LA County Sanitation Districts jointly
funded an advanced wastewater treatment facility in Pomona,
California. The results of the ongoing tests have been compre-
hensively reported by Parkhurst (505) and Chen (119). The ion
exchange system, which was proven to be of economic and technical
feasibility, effectively reduced the total dissolved solids by
90 percent. The treatment involved passage first through a
primary cation column and an anion column, then through a
secondary cation column and a secondary anion column. A series
of 80 complete operating cycles including exchange, backwashing,
and regeneration was completed at a 2.5-gpm flow rate. The
total dissolved solids concentrations of the feed and product
waters averaged 610 mg/a and 72 mg/£, indicating an 89 percent
average reduction. A complete listing of the various consti-
tuents at successive stages of the demineralization sequence is
presented in Table 92 (505).
TABLE 92. AVERAGE WATER QUALITY CHARACTERISTICS OF THE
ION EXCHANGE PILOT PLANT UNDER TYPICAL OPERATING CONDITIONS (505)*
Calcium
Magnesium
Sodium
Potassium
Ammonia, as N
Sulfate
Nitrate, as N
Chloride
Orthophosphate,
as ?OA
Total alkalinity,
as CaCOo
PH
Conductivity
Silica, as Si02
Carbon
Column
Effluent
(feed)
53+
17
126
14
20
72
2.9
135
27
7.4
10
23
Primary
Cation
Effluent
2.0
0.59
61
7.3
9.6
72
2.8
132
27
2.7
9.7
Primary
Anion
Effluent
1.7
0.56
59
7.1
9.2
3.6
1.6
84
15
51
5.7
6.8
Secondary
Cation
Effluent
1.1
0.38
16
1.9
4.0
3.6
1.5
83
14
2.8
5.5
Secondary
Anion
Effluent
(product)
0.60
0.00
15
1.9
3.8
1.3
0.35
14
0.25
39
5.8
3.7
23
*Data taken from May 1968 through December 1968.
tAll constituents in mg/£ except: (1) pH and (2) conductivity (ymhos/cm).
213
-------
All of the major anions and cations were removed to a
considerable degree except silica. Silica removal can be
accomplished, however, with highly basic anion resins (Betz,
63). "Calcium and magnesium, the cations responsible for water
hardness, are almost completely removed in the primary cation
exchanger; but only about half of the sodium, potassium, and
ammonium ions are removed in this column. The secondary cation
exchanger, however, efficiently removed the majority of the
remaining ions. Similarly, the primary anion exchanger removed
most of the sulfate ions, while the nitrate, chloride, and
orthophosphate ions were partially removed by both the primary
and secondary stages.
David Volkert and Associates (157) cited evidence
that the sodium and fluoride concentrations of water can be
reduced by 95 percent using ion exchange. It reported that
chloride, sulfate, and nitrate can be reduced by as much as 95
percent, depending on the degree to which the exchange resin can
be regenerated.
The application of ion exchange to nitrate reduction of
reclaimed wastewaters may be particularly important, as these
waters frequently may contain nitrate concentrations in excess
of the 10 mg/£ limit set by the U.S. Environmental Protection
Agency as an interim primary drinking water standard. The use
of ion exchange resins for the removal of ammonium and nitrate
ions has been discussed in the adsorption section of this report,
Few specific exchange resins are available for removal of the
nitrate ion from wastewater; ammonium ion removal with certain
specific zeolite resins can be quite effective. In wastewater
treatment, significant nitrogen removal may be effected by
removing ammonia with ion exchange; in water purification treat-
ment, nitrate is often the most significant form of nitrogen.
Strong nonspecific anion exchange resins have been applied to
the removal of nitrates from drinking water; but because the
resins are nonspecific, competition from sulfides, chlorides,
silicates, and phosphates limits the target removal of nitrates.
This problem of competing ions may be significant when
considering potable reuse, since reclaimed wastewaters that are
high in nitrates are also likely to be high in these anions.
The caking and clogging problems caused by iron, turbidity, and
colloidal matter are also significant. In other words, ion
exchange technology for nitrate removal is still developing. A
successful application of the available technology has taken
place at Long Island, New York (267,297). A few years ago, Long
Island communities began experiencing rising nitrate levels in
their drinking water supply source. Drinking water was obtained
from groundwater wells that had been contaminated with nitrates
from septic tanks and cesspools. An ion exchange process
originally developed to demineralize industrial process water
was adapted in a prototype ion exchange plant; it reduced the
214
-------
nitrate content of several thousand gallons of the Long Island
water from 22 ppm to 0.5 ppm nitrate. A plant was then built
that successfully provided ion exchange treatment for the Long
Island well water under the constant flow and pressure require-
ments of a municipal water system. However, the well water was
of relatively low total dissolved solids, and it is uncertain
how this process would perform on waters of poorer quality.
A water quality parameter that is of interest in potable
water treatment is color. According to David Volkert and
Associates (157), ion exchange resins have been developed
that will completely remove color-causing organic dye wastes,
humates, and lignates.
ELEMENTAL CONTAMINANTS
Ion exchange techniques have been applied to the treatment
of industrial process water containing trace metals for several
years. Application of these techniques to drinking waters con-
taining trace concentrations of these metals is analogous. In
a review of the literature, David Volkert and Associates
(157) found that several trace elements can be removed from
water to a level of 95 percent. Table 93 lists these elements
and gives the maximum concentrations that can be reduced to
1974 Standards and Guidelines in a single pass through an ion
exchange process (157). Water containing concentrations of a
particular contaminant higher than the maximum listed in the
table can be either passed through a series of ion exchange
columns with different types of resins, or pretreated by a
method such as lime coagulation to precipitate the major amount
of the metal present.
Calmon (99 ) noted that anion exchange treatment can be
used to remove residual arsenic after lime coagulation is used
to precipitate the major amount present. Both weak and strong-
base ion exchange resins appear effective in removing arsenate
and arsenite from drinking water (Patterson, 506). Calmon ( 99)
treating an arsenate water containing 68 mg/a arsenic at pH
6.95 with a weak-base anion exchange resin (lonac A-260),
reported 82 to 100 percent removal. Medium and strong-base
resins (lonac A-300, A-540, and A-550) were less effective.
Again using the weak-base anion exchange resin (lonac
A-260), Shen (576) treated water containing 106 mg/£ of
arsenic. Only 20.7 percent of the arsenic was removed. When
well waters with naturally high arsenic levels were treated,
essentially 100 percent removal was achieved. The disparity of
the results was not explained.
Bone char and activated alumina readily remove arsenic via
an ion exchange mechanism. Arsenic sorption on bone char
results in an irreversible change in the chemical structure of
215
-------
TABLE 93. REMOVAL OF TRACE ELEMENTAL
CONTAMINANTS FROM WATER BY
ION EXCHANGE (157)
Maximum*
Contaminant % Removal Concentration
Arsenic
Barium
Cadmium
Chromium
Copper
Cyanides
Lead
Iron
Manganese
Mercury
Selenium
Si 1 ver
Zinc
95
95
95
95
95
95
95
95
95
95
95
95
95
2.0 mg/
20.0
0.2
1. 0 mg/
20.0
4.0
0.1
6.0
0.1
0.04
0.2
0.1
100
A
£
*Maximum concentration in raw water, which can be reduced to
1974 Standards and Guidelines in a single pass through process,
If raw water concentrations are higher, then combination or
duplication of processes or other processes must be considered,
216
-------
the char. Consequently, exhausted bone char must be discarded;
it cannot be regenerated. Activated alumina is regenerable.
Effective removal of barium by ion exchange has been
reported. Patterson (506) cited a 98.5 percent reduction of
barium from 11.7 to 0.17 mg/j, in a full-scale ion exchange
groundwater softening plant in which a general nonspecific water
softening resin was used.
.According to Patterson (506), ion exchange is a common
method for recovery of cadmium from industrial wastewaters, and
many exchange resins are available with high specificity for
the metal. To meet stringent effluent standards, some industries
are using ion exchange rather than cheaper but less effective
methods to treat chromate and chromic acid waters. With proper
pH adjustment, chromate is removed even in the presence of high
concentrations of sulfate and chloride (506). Reduction of
hexavalent chromium to 0.023 mg/a in a metal finishing waste-
water has been reported (506). Cation exchange can be applied
to remove trivalent chromium, and anion exchange can be employed
to remove chromate and dichromate (506).
Ion exchange is capable of achieving very high levels of
copper removal. Reduction of 1.02 mg/£ copper to less than 0.03
rng/5, has been reported. A selective ion exchange resin (Amber-
lite IR 120) reduced the copper concentration of an industrial
copper plating rinse solution from 45 mg/a to an undetectable
amount (506). Koerts (359) found that ion exchange can remove
copper and zinc from industrial waters to produce effluents
containing as little as 0.04 mg/s, of copper and 0.1 mg/£ of
zinc.
Removal of several metals, such as iron, manganese, lead,
copper, and nickel can be accomplished with ion exchange, but
the processes involve low pH or anaerobic water streams, which
make them normally unsuitable for municipal water treatment.
This technology, however, may be expected to develop as more
attention is given to the application of ion exchange for the
purification of reclaimed municipal wastewaters.
Ion exchange treatment of inorganic mercury-bearing waters
appears to be capable of furnishing an effluent with 1 to 5 ppb
inorganic mercury. Table 94 from Patterson (506) reviews the
experience with ion exchange treatment for inorganic mercury.
Effluent values in the ppb range are indicated. Preliminary
tests have indicated that cation and anion exchange resins in
series can remove 98 percent of both inorganic and organic
mercury forms. Akzo Chemie has developed a special resin for
mercury, which produces effluent levels below 5 ppb mercury (359)
217
-------
TABLE 94. ION EXCHANGE TREATMENT
FOR INORGANIC MERCURY (506)
Resin Type
Mtylon-T
Anion*
Macroreticular
Anion*
Osaka IE*
Osaka MR*
ActiveX
Ajinomoto
Billingsfors
Treatment
PH
5-6
7
na
na
"acidic"
na
na
1.5
6.0
11.0
6.5
Mercury (ygA)
Initial Final
5,000-25,000 1
850 2.5
10,000 <10
470 30
3,000-10,000 100-150
100-150 2-5
10 <5
60 5
87 3
1 ,800 990
35 1
Additional
Treatment
--
--
--
Prefilter
Osaka IE Resin
--
--
--
--
--
Percent
Removal
100
99.7
100
94
98
98
50
92
97
45
97
*Mercury removed as mercuric chloride complex, HgCl
(2-x)
Patterson (506) presented evidence that cation plus anion
exchange applied to secondary wastewater effluent can remove
selenium to a level of 99.7 percent. He also cited an example
of 85 percent removal of silver from an extremely dilute
secondary sewage effluent by cation exchange, and 91.7 percent
removal by combined cation-anion exchange.
Calmon (100) discussed the use of ion-exchange for trace
heavy metal removal. As part of his paper, he listed the
specific resins that can be used to remove various heavy metals
These are as follows:
Element
Arsenic (3+)
Beryl 1ium
Bismuth
Boron
Cesium
Cobalt
Copper
Germanium
Gold
Polar Group
F1 u o r o n e
Phosphonic diallyl phosphate
Pyrogallol
N-methyl glucamine, tris hydroxymethyl
amino methane
Phenolic OH + sulfonic groups
M-phenylene diamine, 8-hydroxyquinoline
Phenolic OH + phosphonic groups,
8-hydroxy quinoline
m-phenylene diamine
imino diace tic acid
a 1g i n i c acid
Phorone
Pyridinium, thiourea
218
-------
Element Polar Group
Iron Alginic acid
m-phenylene diamine
hydroxamic acid
phosphonous
phorone
chlorophyll
haemin deriv.
Lead Pyragallol, phosphoric
Mercury Thiourea, thiol, iminodiacetic acid,
mercapto resins
Nickel Alginic acid, dimethylglyoxime
Potassium Dipicrylamine
Strontium Phosphorous
Titanium Chromotropic acid
Uranium Pyridinium, phosphorous ester
Zinc Anthranilic
Zirconium Phosphate ester
He also discussed the various types of exchangers, dosages,
operating problems, etc., that can be anticipated for removal
of each metal.
BIOCIDAL CONTAMINANTS
Ion exchange units are not specifically designed to remove
biocidal contaminants. However, some incidental removal of
these pesticides, insecticides, and herbicides may occur due to
adsorption on the resin material. This phenomenon will occur
until the adsorptive capacity of the resin is exhausted.
SYNTHETIC/ORGANIC CONTAMINANTS
Because many of the synthetic/organic contaminants have
chemical and physical properties that are similar to the
biocidal contaminants, the same considerations apply here as in
the biocidal section.
BIOLOGICAL CONTAMINANTS
Since the primary removal mechanism of ion exchange is
based on particle charge properties, any removal of the
biological contaminants will be incidental. Any removal that
does occur will probably be due to mechanical filtration.
219
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ADVANCED WATER TREATMENT: REVERSE OSMOSIS
INTRODUCTION
For readers unfamiliar with the osmotic membrane process,
one can picture these membranes as thin sheet filter materials.
Initial investigators thought that the membranes acted as
strainer-type materials with such small pore sizes that most
ionic and biological molecules were too large to pass through.
Recent studies with electron microscopes have shown that
removals are controlled by molecular diffusion through the
membrane and that salts and other impurities diffuse much more
slowly than water (652). The differential pressure to provide
a driving force through the membrane is supplied by pumps. The
discarded flow of concentrated contaminants is continuous,
and its volume normally equals from 5 to 30 percent of the
volume of the process influent volume. Membrane fouling by
suspended solids, organic slimes, and precipitates is a problem
unless substantial pretreatment of the influent water is pro-
vided. Therefore, reverse osmosis (RO) is normally located as the
last unit process in the water treatment chain.
Very little actual operating data are available regarding
the use of reverse osmosis for treatment of municipal
water supplies, because the quality provided by reverse osmosis
systems has not as yet been required. Even in areas of high
TDS that could benefit from RO treatment, the cost of this
unit process has been prohibitive. There has, however, been
a substantial amount of research conducted on the use of RO
for polishing highly treated wastewaters. This research,
though, primarily focuses on the removal of selected contami-
nants from solution in laboratory and pilot scale projects.
Since these are similar in many respects to raw water supplies,
performance is often analogous to water treatment situations.
Reverse osmosis may become more important in the future
as both a tertiary wastewater and raw water supply treatment
process, because of its capability to remove a high percentage
of all types of general, elemental, and biological contaminants
as well as many synthetic/organic and biocidal constituents.
With the recent concern over even very small concentrations of
heavy metals, residual organics, and toxic compounds in water
supplies, RO with its >99 percent removal efficiency may see
increased usage, albeit at a high cost.
220
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Aqueous solutions of two or more solutes reacting with a
membrane may give product flux and solute retentions that are
quite different from those predicted from the behavior of
solutions of the individual salutes. This results from inter-
actions between solutes, their products, and the membrane.
Improved retentions of solutes have been observed when mixed in
partially treated wastewaters, thus increasing the attractiveness
of wastewater RO treatment for reuse (191). Improved retentions
are thought to be due to synergistic effects among the high
molecular weighted components.
Various types of membrane systems have been tested on a
variety of wastewater effluents from primary to highly
treated tertiary. Laboratory tests have also been conducted
on the removal of many synthetic/organic chemicals and bio-
cidal compounds. The RO process does not destroy any of the
input contaminants, but only separates them into two streams,
with the waste stream containing the rejected materials.
Depending upon the feed conditions and the desired objectives,
the product water volume can range up to 95 percent of the
total influent, with the remainder representing the discarded
flow. The characteristics of RO membranes can be controlled
within a wide range by controlling the manufacturing variables.
In general, as one improves the contaminant removal efficiencies,
the flux per unit area decreases. This type of trade-off
implies that the systems can be optimally designed to achieve
the desired objectives.
For this study, the literature reviewed was oriented
towards tertiary wastewater applications as well as laboratory
and pilot scale tests of osmotic membranes. The literature
excluded the extensive basic research on osmotic membranes
for other applications (e.g., industrial wastewater treatment).
The very extensive patent literature on the different types
of membranes, designs, and manufacturing processes was also
excluded. Table 95 provides a summary of the current literature
pertaining to the performance of reverse osmosis units.
WATER QUALITY PARAMETERS
RO systems are not commonly used specifically for general
contaminant removal from water supplies (with the exception of TDS), as these
constituents can be sufficiently removed by other less expen-
sive treatment units. However, there were quite a few references
that noted the performance of RO on general contaminant removal
from wastewaters as shown in Table 95. The performance of RO
systems in terms of percent removal is excellent (90 to 99+
percent) for all general contaminants except for low molecular
components of BOD, or COD, and
221
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TABLE 95. LITERATURE REVIEWED PERTAINING TO REVERSE OSMOSIS
Contaminant
Reference Number
Water Quality Parameters
ABS
NH4
BOD
COD
Chlorides
CN
Fluorides
Hardness
N0
so4
TDS
Elemental Contaminants
Aluminum
Arsenic
Barium
Boron
Cadmium
Chromium
Copper
Iron
46, 281, 286, 449, 593
120, 148, 149, 182, 281, 294, 449, 593
148, 286
120, 148, 149, 182, 189, 371, 449, 593,
615
120, 148, 149, 294, 449, 593, 671
294, 671
148, 294, 671
286, 294, 449
140, 148, 182, 281, 286, 294, 593
120, 148, 149, 182, 281, 286, 294, 449,
593
120, 148, 149, 294, 449, 593
120, 148, 149, 182, 281, 286, 371, 449,
593
148, 294
157
157
148, 157, 294, 671
157, 294, 615
148, 157, 294, 615, 671
157, 294, 615, 671
157. 294, 449,. 593, 615
222
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TABLE 95 (continued)
Contaminant Reference Number
Lead 615
Magnesium 120, 148, 149, 294, 449, 578, 593, 671
Mercury 157
Nickel 615, 671
Potassium 148, 149, 294, 449, 578, 593
Selenium 157
Silver 157, 615
Zinc 157, 615
Biocidal Contaminants
DDT 46, 126
ODD 46, 126
Aldrin 126
Organophosphorus 126
insecticide
Chlorinated 126
hydrocarbons
D i e1d r i n 126
Herbicides 126
Lindane 46, 126
Pesticides 126, 191
Synthetic/Organic
Contaminants
Misc. organics 46, 148, 189, 281
Biological Contaminants
Bacteria 148, 294
Virus 148
223
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Several references discussed the removal of ABS from
solution. The presence of highly nonbiodegradable alkyl
benzene sulfonate (ABS) even in concentrations of only 1 mg/l
can produce undesirable frothing and foams although health
implications do not appear significant. Hauck and Sourirajan
(286) reported removals of 99+ percent with a high feed con-
centration of 300 mg/l . Merten and Bray (449) and an EPA
study (593) both reported ABS rejection of about 98 percent
with a variety of membranes. Bennett et al. (46 ) tested RO
performance on a vast array of organics. They showed ABS
removals of 90 percent at a 14 gpd/ft^ flux.
Many studies were conducted that included ammonia removal
(see Table 95 ). Reported removals ranged from 60 to 97
percent. Since ammonia concentrations are not generally
of significance in water supplies and NH is readily oxidized
in treatment processes, further discussion is not necessary
here.
Hauck and Sourirajan (286) studied the performance of RO on
hard water and on wastewater. The average BOD removal from
secondary effluent was 85.8 and 80.8 percent at 1,000 and 500
psig, respectively. Cruver (148) reported secondary
effluent BOD rejections varying from 81 to 94 percent with a
cellulose acetate membrane.
COD removal is studied more frequently than BOD removal
in regard to RO performance, because many of the nonbiodegradable
constituents of COD can be effectively removed by RO. A review
of all nine references reporting on COD removal shows a removal
range of 90 to 99+ percent with an average of about 95 percent.
As a typical example, one of the larger scale pilot programs
performed at Hemet and Pomona, California (615), found that
RO provided very good removals of trace organics. The COD of
secondary effluent was reduced from 39 mg/l to 1 mg/£ at
Pomona, while activated carbon effluent COD was reduced from
11.4 mg/l to 0.3-1.0 mg/£ . Similar removals were reported
from the RO pilot plant at Hemet. It was found that although
RO was capable of greatly reducing effluent COD concentrations,
the costs for full-scale operation are very high.
Chloride is readily removed by RO. Many studies have
evaluated this constituent with removals ranging from 85 to
97 percent (120, 148, 149, 294, 449, 593, 671).
Two references included CN removal in research efforts
(294, 671). Hindin and Bennett (294) found that CN removals
ranged from 79 to 85 percent at a flux of about 18 gpd/ft . A
summary report (671) listed typical CN removal at about 90
percent.
224
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A study by Cruver (148) reviewed RO performance in removing
various contaminants. It was found that fluoride removals
ranged from 88 to 98 percent using selective cellulose acetate
membranes. Hindin and Bennett (294) and reference 671 reported
similar results.
RO units are highly efficient at removing hardness (Ca
and Mn++) from water supplies. Hauck and Sourirajan (286)
summarized the effects of RO treatment of hard-water supplies
in five cities and formal removals ranging from 96 to 99.9
percent as CaCOs. Operating pressure was 1,000 psig with a 90
percent product recovery. Performance was directly related to
flux, with the higher removals achieved at lower flowrates.
Merten and Bray (449) also reported removals at roughly 99 per-
cent for the more efficient membranes they analyzed.
The reviewed data indicates that nitrate nitrogen is one
of the most difficult compounds for RO processes to remove
(593). Hauck and Sourirajan (286) reported NO^-N removals
ranging from 50 to 60 percent. Extensive pilot testing by
the EPA at Pomona, California, showed NOo-N removals of 54 per-
cent over the first 9,475 hours of operation (120). The five
other references showed similar poor removals ranging from
51 to 86 percent and averaging around 60 percent.
Both P04= and S04=, on the other hand, were very readily
removed by RO processes. All references reviewed showed
removals of 94 percent or better, some up to 99.9 percent.
The primary water treatment use of RO units is to reduce
the TDS concentrations of highly mineralized waters. One full-
scale example of this is the Orange County Water Districts
Water Factory 21 (371) where 5mgd of highly treated effluent
is given RO treatment prior to recharge of potable aquifers.
Results from the operation to date show a 90 to 95 percent
TDS removal at 90 percent feed recovery. Results from other
references using various membranes, pressures, and fluxes
showed that average TDS removals were about 91 percent and
ranged from 89 to 99 percent. Removals can be controlled by
membrane selection and adjustment of flux. Studies of pilot
RO systems at Pomona (120) showed TOC removals of 86 percent
when using primary effluent on the feed.
The major problem areas associated with general contaminant
removal are fouling, short membrane l*fe, and associated
engineering problems. If the membrane life and flux rate prob-
lems are solved, the RO membrane technology may become applicable
to wastewater treatment where some sort of reuse is desirable
and salt content would restrict reuse. At present, the tubular
type membrane systems appear to be more applicable to sanitary
wastewaters due to the lower fouling and easier cleaning
225
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inherent in this type of design. This advantage may not be as
significant in potable water treatment.
ELEMENTAL CONTAMINANTS
A good deal of available literature on RO membranes
deals with removal of elemental contaminants. RO systems can
be designed to remove almost any elemental contaminant existing
in either an ionic form or colloidal form in water. Generally,
multivalent ions (Fe+3, Cu*"1", Zn++, S0«)are rejected more
effectively than monovalent ions (B+, NOo). As previously
mentioned, the percentage removal will depend upon the specific
membrane and manufacturing procedures. Most references provide
a lengthy list of contaminant removals. It would be redundant
to discuss each of them here. References 154, 294, and 615
provide typical summaries of the performance of reverse osmosis
units in removing elemental contaminants. Results are shown
in Table 96. AS shown, RO is generally very effective.
TABLE 96. REVERSE OSMOSIS REMOVAL OF
ELEMENTAL CONTAMINANTS (REF. 154. 294, 615)
Percent Removal (Single Pass)
Contaminant Reference 154 Reference 294 Reference 615
Aluminum
Arseni c
Barium
Boron
Cadmium
Chromium
Fluorides
Copper
Lead
Iron
Manganese
Mercury
Nickel
Selenium
Si Tver
Zinc
-
90-95
90-95
-
90-98
90-97
90-97
90-97
90-99
90-99
90-99
90-97
- *
90-97
90-97
90-99
97
-
-i
50
68-70
93-98
88-98
82-96
-
95-98
-
-
-
-
,
-
-
-
-
-
66-98
82-98
-
99
99
94-99
-
-
98-99
-
96
97
226
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BIOCIDAL CONTAMINANTS
A few studies have been conducted on the removal of bio-
cidals by osmotic membranes ( 46, 126, 191). Excellent
removals were reported for a wide variety of pesticides,
insecticides, and herbicides including chlorinated hydrocarbons,
organophosphorus compounds, and halogenous cyclodienes.
However, a considerable amount of this removal can be attributed
to adsorption or absorption on the membrane itself. Since
these tests were for short time periods relative to commercial
application, the long-term rejection may be more complex and
may depend upon whether the contaminant is adsorped or absorbed
and upon the diffusion rates through the membrane.
With such a large percentage of the removal being related
to adsorption/absorption, it is clear that different types of
membrane materials will show significantly different results.
For example, cellulose acetate (CA) membranes show rather
poor performance on the more polar randox and atrazine, whereas
the less polar polythyl enimine-based membranes showed satis-
factory performance. Since the active surface on some types
of membranes is on the order of a few tenths of a micron, any
significant amount of absorption can change the membrane compo-
sition and possible rejection of other contaminants.
Edward and Schubert (191) summarized some results of various
studies using cellulose acetate (CA) membranes for the removal of
the common pesticide 2, 4-D. Results varied widely from 57 to 99+
percent removal depending on influent concentrations, esterifi-
cation, and feed rate. Performance for removal of the insec-
ticide lindane was also sporadic, ranging from rather poor
removals up to 84 percent. DDT and ODD have a very low solu-
bility and tend toward micelle formation thus enhancing RO
performance. Reported DDT and ODD removals were 97 to 99
percent (157, 191 ).
Chian et al. (126) performed a detailed analysis of the
performance of RO units in removing biocidals. Two types of
membranes were evaluated, cellulose acetate (CA) and cross-
linked polyethylenimine: (NS-100). With each membrane, rejection
of all types of pesticides (chlorinated hydrocarbons, organo-
phosphorus, and miscellaneous) was greater than 99 percent.
Specifically, the following chlorinated pesticides were retained
at greater than 99 percent: aldrin, lindane, heptachlor, hepta-
chlor epoxide, DDE, DDT, and dieldrin';
Of the organophosphorus pesticides, diazinon was removed
at greater than 98 percent, and methylparathion. malathion,
and parathion at greater than 99 percent. The lowest removals
were reported with the CA membrane on randox (72 percent) and
atrazine (84 percent). A significant portion of the pesticide
removed was adsorbed on the membrane itself: about 80 to 95
227
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percent for hydrocarbons, 30 to 50 percent fororganophosphorus
compounds, and 5 to 60 percent for the miscellaneous pesticides.
Bennett et al . ( 46 ) reported on the removal of organic
refractories including some biocidals. They found that lindane
removal was 84 percent; DDT, 99+percent; and casein, 99 percent.
The literature data indicate that removal of biocidals is
highly variable, depending not only on contaminant concentra-
tions and membrane characteristics, but on synergistic effects
of other components in the water. In any case, RO provides a
high level of treatment for many of the common pesticides and
insecticides.
SYNTHETIC/ORGANIC CONTAMINANTS
The performance of RO membranes with respect to removal of
synthetic/organic contaminants is similar to that of many of
the biocides. In general, these contaminants can be adsorbed,
absorbed, rejected or transmitted by the membrane, w.ith removals
depending on chemical species and membrane type. In general,
larger molecular weight compounds are readily rejected or
sorbed by the membrane, whereas low molecular weight compounds
(<100) are more likely to pass through.
Studies by Duvel and Helfgott (189) on cellulose acetate
(CA) type membranes have shown that rejection of low molecular
wet organics depends upon the molecular weight and molecular
size (as determined by steric geometry, with the size being more
important); it also depends on the ability of the molecule to
form hydrogen bonds. The hydrogen bonding behavior affects the
solubility in the membrane surface and hence the permeability.
Studies by Hamoda et al. (281) have shown that high
flux membranes can be developed that have good rejections (>99
percent) of tested organic compounds such as sucrose, glutamic
acid, starch, sodium stearate, ABS, LAS, and beef extract.
Cruver (148) reviewed similar contaminant removals and listed
sucrose at 99.9 percent and glucose at 99.5 percent.
Bennett et al. (46) performed a comprehensive study of
the removal of organic refractories by RO. Results showed
that the RO process is capable of producing a product water
that is extremely low in organic matter in aqueous solution or
dispersion, with the exception of those organic compounds that,
when in solution or dispersion, have a lower vapor pressure
than water.
The classes of compounds that do not appear to be well
rejected and are present in wastewater effluents include com-
pounds such as methanol , ethanol , and phenol. No data were
228
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found on the low-molecular-weight, halogenated hydrocarbons
such as chloroform, bromoform, halogenated ethane, or ethylene
compounds; but, based on the present theoretical knowledge, one
would expect the removals to be poor.
BIOLOGICAL CONTAMINANTS
Due to the large size of biological contaminants, including
virus, relative to the effective pore size of RO membranes, high
reductions of these contaminants can be expected.
Hindin and Bennet (294) conducted microbiological studies
to determine the permeation through a porous cellulose acetate
membrane of microorganisms found in sewage effluent. Their
results showed that Escherichia coli. Aerobacter aerogenes,
coliphage T-7 and X-175. and Streptococcus narcesence were all
removed 100 percent by the RO unit, with the exception of one
test in which a leak in the membrane may have permitted per-
meation.
Cruver (148) reports that several studies have shown that
99.9 percent removals of bacteria and virus can be attained.
However, even with these excellent removals, RO processes
are not used alone for disinfection because of the presence
of imperfections in the membranes. These systems are primarily
designed for TDS removal in which small leaks through the
membrane and at seal joints are generally inconsequential.
Nevertheless, these leaks could be significant when they reduce
the removal of virus and bacteria from 99.9999 to 98 percent.
To depend upon these systems for 100 percent biological con-
taminant removal would require continuous monitoring for
biologicals and a degree of quality control that would be
considered beyond the state of the art for field systems.
The present literature indicates that whereas removals
of biological contaminants with RO are very good, they are not
as high or as fail safe as other disinfection practices'
(chlorination, ozonation). It should also be remembered that
RO is only a separation process, not a destruction unit, and
that the biological contaminants, once removed, will remain in
the waste solution.
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SECTION 11
EPIDEMIOLOGICAL AND PATHOLOGICAL EVALUATION
OF WASTEWATER CONTAMINANTS
INTRODUCTION
Many contaminants contained in municipal wastewater are
known to produce adverse human health effects. A number of
elemental, biocidal, and synthetic/organic constituents have
been clearly identified as potential carcinogens; some have
even been identified as being mutagenic or teratogenic.
Although the epidemiological effects of various viruses and
bacteria are known and predictable, knowledge of the health
risks of certain other contaminants is incomplete or lacking.
Moreover, some chemical substances work not only in isolation
within the human body, but may react synergistically (two or
more chemicals combining to produce a net effect that is
greater or lesser than that produced if the chemicals act
independently). A multiplicity of factors is involved in
such reactions, and knowledge of potential health risks is
scant.
Literature detailing the epidemiological and pathological
effects of wastewater constituents has been surveyed; the
principal health problems posed by these contaminants are
summarized below. A sound understanding of human physio-
logical reactions and consequent public health threats will
better prepare responsible authorities to assess treatment
performance and set acceptable standards.
Present standards controlling wastewater discharges and
drinking water supplies have been assumed by many to guarantee
adequate protection of public health. However, recent in-
vestigation has shown that some residual organics, carcinogenic
chlorinated hydrocarbons, synthetic compounds, trace elements,
and biocides are harmful even in extremely small concentra-
tions. Existing standards are called into question by this
increasing knowledge: there may be no "safe" threshold for
some of these chemicals. Growing epidemiological and patho-
logical evidence must be taken into account if discharge and
drinking water standards are to safely ensure public well-
being.
230
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WATER QUALITY PARAMETERS
Suspended solids, BOD, TOC, and most other constituents
of general water quality have no direct effect on public
health. However, certain constituents may become associated
with other, more directly harmful, contaminants. The sur-
vival and potential health threat of such contaminants may be
magnified as a result of this process. Moreover, nitrogen
species present in wastewater can directly affect human
health.
Nitrogen
Nitrogen in wastewater effluent is usually found in one
of the stable forms (ammonia, nitrate, or organic nitrogen)
rather than the more hazardous nitrite form. Nitrates and
nitrites occur in drugs, food, and water. Man is continually
exposed to small amounts of these substances, which usually
cause no harm. In high concentrations and under special cir-
cumstances, however, they may cause illness and even death.
Sapp (572) and the Hazardous Waste Advisory Committee of the
EPA (484) consider nitrite, in particular, a significant
health problem.
Nitrite toxicity is the major health problem associated
with these nitrogen species since nitrate easily reduces to
the toxic nitrite form. Such a conversion may occur outside
the human body in food or water containing nitrates Con-
version can also take place inside the body through the
action of intestinal bacteria on ingested nitrates.
Nitrate/nitrite conversion that occurs during digestion
requires special conditions likely to be present only in
infants. The foremost prerequisite is the presence of
nitrate-reducing bacteria in the upper gastrointestinal
tract. Such bacteria are not normally present so high up in
the intestinal tract. This circumstance, however, may
occasionally occur in infants, particularly those with gastro-
intestinal infections and a gastric pH insufficiently acidic
to kill the bacteria.
Acute nitrite toxicity (methoglobinemia) occurs when
hemoglobin (the oxygen-carrying red pigment of blood) is
oxidized into methemoglobin (a brown pigment incapable of
carrying oxygen). Methemoglobin constitutes about 1 percent
of the total hemoglobin of a healthy adult and up to
approximately 4 percent of that of a healthy newborn infant.
Cyanosis results when roughly 15 percent of the hemoglobin
in blood is converted into methemoglobi n; when tnethemogl obi n
constitutes 70 percent or more of the total hemoglobin,
oxygen transport is severely impeded, and death may occur (484)
231
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Infants, then, are particularly prone to nitrate-
induced methemoglobinemia. In addition to the presence of
nitrite-reducing bacteria in the upper gastrointestinal
tract as mentioned above, (1) the hemoglobin of very young
infants is oxidized twice as rapidly as that of adults by
nitrate to form methemoglobin; (2) the red blood cells of
infants are not able to reduce methemoglobin into hemoglobin
as well as adult cells; and (3) the total fluid intake of
infants per unit of body weight is much greater than that of
adults. Thus, for a given concentration in fluids, infants
consume proportionately more nitrate than adults.
The consumption of water containing high levels of
nitrates has accounted for many more cases of methemoglobin-
emia than all other causes combined. Methemoglobinemia of
such etiology has been reported only in infants, although one
study documents one occurrence resulting from the use of
nitrate-contaminated well water for peritoneal dialysis in
an adult. In the United States only one case has been
associated with water from a public water supply; all the
rest (about 300) have been due to well water (484).
Standards for nitrates in drinking water limiting nitrate
to 10 mg/i expressed as nitrate-nitrogen (45 mg/£ expressed
as nitrate) were set by the U.S. Public Health Service in
1962. The 10-mg/£ nitrate-nitrogen level was set because
there had been no reports in this country of infantile
methemoglobinemia associated with the ingestion of water
containing nitrate at levels below 10 mg/l. In addition,
this level was set because it was a standard that could be
met easily by most municipal water supplies. After publica-
tion of these standards, however, data reported from other
countries revealed that a small percentage of cases had
occurred where the water nitrate-nitrogen content had been
below 10 mg/£.
As a consequence, the 1962 standards are currently under
revaluation. Several studies have been designed to determine
more specifically the exact nitrate levels in water required
to cause elevated levels of methemoglobin and clinical
evidence of methemoglobinemia in infants. Preliminary re-
sults suggest that the 1962 standards provide adequate pro-
tection against clinical methemoglobinemia. However, sub-
clinical elevations of methemoglobin have been found in
infants with diarrhea or respiratory disease, consuming water
with a nitrate content below the 10 mg/t level (484).
In contrast to the relative wealth of data on acute
toxicity in humans, reliable data are lacking on the physio-
logic effects, if any, of chronic nitrate/nitrite toxicity
or of mild, noncyanotic methemoglobinemia. Studies in
animals indicate that nitrates and nitrites may, on occasion,
232
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cause vitamin A deficiency, and that nitrates may have an
antithyroid effect by increasing the need for iodine. No
data are available to indicate whether such effects can
occur in man.
Chronically elevated levels of methemoglobinemia may
have some effect on the human brain: abnormal changes on
electroencephalograms have been observed in rats given 100 to
2,000 mg/£ of sodium nitrite each day for two weeks. A
Russian study purports to show decreased response to visual
and auditory stimuli in school children with a mean methemo-
globin level of 5.3 percent of total hemoglobin. However, the
study was poorly controlled, and the results are inconclusive.
There have been patients with hereditary methemoglobinemia
and mental retardation, but the association may be coincidental
Most patients with hereditary methemoglobinemia show no
mental or neurologic abnormalities (484)
Nitrosamines formed by the reaction between nitrites and
amines have been proven hazardous to human health. Nitrites
and/or precursor nitrates are found in foods, water, and drugs;
amines are found in tobacco smoke, beer, tea, wine, and tooth-
paste as wel1.
Nitrosamines have potent biological effects, including
acute cellular injury (primarily involving the liver), car-
cinogenesis, mutagenesis, and teratogenesis. To date,
approximately one hundred nitrosamines have been tested in
animals. The vast majority has proved to be carcinogenic.
Many organs (liver, esophagus, and kidneys) that are common to
diverse species of animals are susceptible to the cancer-
producing effects of these compounds. These effects can be
elicited experimentally by various routes of nitrosamine
administration (oral, intravenous, inhalation) at extremely
low doses. In some instances, cancer can develop after a
single exposure(484).
Concerns about potential nitrosamine hazards to human
health arise from the possibility for (1) contact with pre-
formed carcinogenic nitrosamines and (2) the formation of
carcinogenic nitrosamines within the human body after exposure
to precursor nitrites and amines. The possible formation of
carcinogenic nitrosamines in the human gut through the
combination of ingested nitrites and amines is of critical
concern. Such reactions have been demonstrated to occur
both in vitro and in vivo (in animals).
Studies in humans that were fed nitrate and a noncarcino-
genic nitrosamine precursor amine (diphenylamine) have shown
that diphenylnitrosamine can be formed in the human stomach.
Nitrosamine determinations in these studies were made by
233
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thin-layer chromatography, a method now known to give false
positive results. Unfortunately, these data have not yet
been confirmed using the newer and more reliable techniques
of gas-liquid chromatography and mass spectrophotometry (484).
ELEMENTAL CONTAMINANTS
It is often difficult to assess the health effects of
metals and their compounds: many metals are essential to
life at low concentrations but toxic when concentrations ex-
ceed tolerance in man. The situation is further complicated
because the various chemical states of metals (pure metal,
inorganic or organic-metallic compounds) react differently
within the body. Individual differences between subjects,
incubation periods, and sites of accumulation of the sub-
stances in the body are also significant factors in toxicity.
In addition, results from experiments with animals may not
be readily applicable to humans. Experimental animals such
as rats and mice have a much shorter life-span than man and
react and respond differently to chemicals because of their
own distinctive physiological processes.
Table 97 gives a comprehensive summary of the presence
of metals in the environment, their toxicity to humans, and
their half-life in the body (the time it takes for one-half
the chemical to be excreted). Five heavy metals --cadmium,
lead, mercury,nickel as nickel carbonyl, and beryllium --
represent known hazards to human health. Lead, mercury, and
cadmium are particularly insidious,because they can be re-
tained in the body for a relatively long time and can
accumulate as poisons. Antimony, arsenic, cadmium, lead, and
mercuric salts are the most toxic. Discussions of fatal
doses and other considerations can be found in each individual
metal section.
Lead
Lead is a cumulative poison. However, except in cases of
prolonged exposure at high concentrations, most of it is absorbed
into the blood and is later excreted in the urine. The blood lead
does not rise to acute levels; however, a small portion of the
daily lead intake gradually accumulates in bones, where it
is normally insoluble and harmless. Under certain conditions,
such as periods of high calcium metabolism in feverish
illness, cortisone therapy, or old age, this accumulated lead
can be released suddenly into the blood at toxic levels. A
fatal dose of absorbed lead has been estimated to be 0.5 g;
ingestion of more than 0.5 mg/£/day may, because of the above-
mentioriPd accumulation, cause toxicity and death.
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METALS IN THE ENVIRONMENT AND THEIR TOXICITY1
ro
CO
en
Metal Food
Antimony
Arsenic
Barium
Beryl 1 i urn
Cadmi urn
Chromium
Copper
Iron
Lead
Manganese
Mercury
Nickel
Selenium
Silver
Tin
Zinc
a Data primarily
(ppb) (ppb)
and Water Air
100
400-900
735
12
1.7
30
0.04
20 to 100 7.4
245
1,325
15,000
300
4,400
25
600
62
60-80
7,300
14,500
from Drei
Oregon State University
b Copper sulfate
1.1
11.4
84
46
28.8
2.36
--
0.6
16.8
i
sbach (181 )
(288)
Oral dose
producing
toxicity (mg)
100
5-50
200
--
3
200
50-250
--
--
5
60
2,000
and
c A two-yr old child
Fatal
dose
(ingestion)
100-200 mg
120 mg
1 9
5 g
10 gb
5-10 gc
0.5 g
ft
20 mg - 1 g
^
29f
10gg
d Mercuric salts
e Methyl mercury
f Silver nitrate
g Zinc sulfate
Total
Body content
(mg)
7.9
15-20
22
0.3
50
1.8
72
4,200
120
12
--
10
14.6
1
17
2,300
Whole body
half-life
(days)
38
280
65
180
25 years
616
80
800
1,460
17
-,«e
70
667
n
5
35
933
-------
Lead prevents the formation of hemoglobin in the blood
by interfering with the synthesis of certain precursors
(prophyrins), which leads to the anemia present in chronic
lead poisoning. Lead also inhibits the sulfhydryl enzymes
that catalyze many of the metabolic pathways, including the
biosynthesis of heme. The effects of lead on the brain and
peripheral nervous system are most serious, manifested as gas-
trointestinal or central nervous system disturbances and
anemia. Symptoms of acute poisoning include metallic taste,
abdominal pain, vomiting, diarrhea, black stools, oliguria.
collapse, and coma. Symptoms of chronic poisoning in early
stages include loss of appetite and weight, fatigue, head-
ache, lead line on gums, loss of recently developed skills,
and anemia. In advanced stages, there is intermittent vomit-
ing, irritability; nervousness; lack of coordination; vague
pains in arms, legs, joints, and abdomen; paralysis; disturb-
ances of menstrual cycle; and abortion. Exposure to tetra-
ethyl lead or tetramethyl lead causes insomnia, disturbing
dreams, emotional instability, hyperactivity, and even toxic
psychosis. Severe symptoms include persistent vomiting,
papilledema, ataxia, encephalopathy (any disease of the brain)
elevated blood pressure, cranial nerve paralysis, delirium, con-
vulsions, and coma (131).
There are up to 100 cases of lead poisoning reported in the
U.S. annually; an average of 10 are fatal. Most of the fatalities
are related to children who ingested lead-based paint from homes
built before 1940; however, 7 cases of lead poisoning were
reported from drinking well water in Australia in 1973 (57, 144).
The well water contained a soluble lead content of about 14 mg/l\
Mercury
Neither methyl nor elemental mercury is normally found
in dangerous concentrations in air, water, or most common
foodstuffs. There are three principal ways in which man can
be poisoned by methyl mercury: (1) when food is consumed that
has been contaminated with methyl mercury, e.g., seed con-
taining mercury fungicides (HgCl2); (2) when methyl mercury
used or formed in industrial processes is intentionally or
unintentionally dumped into natural waters, reaching man
directly through the water and indirectly through the food
chain; and (3) when nontoxic inorganic or organic phenyl
mercury is converted into toxic alkyl mercury compounds by
microorganisms in the environment and is passed on to man
through the food chain (329).
The acute toxicity of methyl mercury is the result of
almost complete (98 percent) absorption of the compound
from the gastrointestinal tract. Ingested metallic mercury
is not toxic since it is not absorbed. Mercurous chloride
and organic mercurials such as acetomeroctol, ammoniated
236
-------
mercury, merbromin, mercocresol, and mercury protoiodide
are not likely to cause acute poisoning because they also
are poorly absorbed. The single fatal dose of these compounds
is 3 to 5 times the fatal dose of soluble mercury salts. The
mercurial diuretics (mersalyl, meralluvide, mercurophyl1ine,
mercumati1 in, mercaptomerin, chlormerodrin, and merethoxyl1ine)
are almost as toxic as mercury salts. Volatile diethyl and
dimethyl mercury are 10 times as toxic as mercuric chloride
(695). The fatal dose of mercuric salts is 20 mg to 1 g. The
biological half-life of methyl mercury is estimated to be about
70 (30 to 100) days as shown in Table 97 (615,672).
Acute poisoning by ingestion of mercuric salts causes
metallic taste, thirst, severe abdominal pain, vomiting, and
bloody diarrhea. Death is from uremia (an excess of urea
and other nitrogenous waste in blood). Ingestion of insol-
uble or poorly dissociated mercuric salts (including mercurous
chloride and organic mercurial compounds) over a prolonged
period causes urticaria progressing to weeping dermatitis,
stomatitis, salivation, diarrhea, anemia, liver damage, and
renal damage progressing to acute renal failure with anuria
(total suppression of urine). In children, repeated ad-
ministration of calomel (Hg2Cl2) appears to be the cause of a
syndrome known as erythredema polyneuropathy. In fatalities from
mercury poisoning, the pathologic findings are acute tubular
and glomerular degeneration or hemorrhagic glomerular
nephritis. The mucosa of the gastrointestinal tract shows
inflamation, congestion, coagulation, and corrosion (181).
Mercurialism is manifested primarily in kidney, liver,
or brain damage in animals. Exposure to inorganic mercury
compounds usually results in kidney damage, while alkyl
mercurialism is characterized by brain damage. However, some
degree of both kidney and neurological injury results from
exposure to either category of mercurials. Mercury poisoning
apparently damages Kreb's cycle enzymes (which catalyze the
oxidation of tricarboxylic acids) and protein synthesis,
leading to kidney and brain damage (216).
Methyl mercury has an affinity for the fetus and is terato-
genic in its effect, as it readily penetrates to the fetus through
the placenta. In addition, the cytogenic toxicity of methyl
mercury is potentially greater than that of any other known sub-
stance. The urine and especially the feces are the most important
means of mercury elimination.
The tragedy of Minamata Bay, Japan, which occurred from
1953 to 1961, is one of the best documented cases of mercury
poisoning. In essence, it was concluded that the disease --
which had felled many inhabitants of the fishing villages
on the shores of Minamata Bay -- had resulted from mercury
poisoning. A chemical plant in the area used mercurv chloride
237
-------
as a catalyst in the production of vinyl chloride. The waste
containing the mercury washed off the product was discharged
into the bay, and was ingested by the shellfish therein. Some
114 cases of "Minamata disease" were reported, as well as
44 deaths and 22 cases of brain damage in 400 live births (423)
A similar disaster struck at Niigata, Japan, where 120
persons were poisoned (423).
Nickel
The fatal dose of nickel is not know, but its whole body
half-life is about 667 days. Inhaled nickel carbonyl decomposes
to metallic nickel, which deposits on the epithelium of the lung.
This finely divided nickel is rapidly adsorbed and damages the
lung and brain. The principal manifestation of nickel carbonyl
poisoning is dyspnea (difficult respiration). Workers exposed
to nickel carbonyl show a high incidence of lung cancer, and
some workers develop dermatitis (181). Very little is under-
stood about the adverse health effects of nickel in waste or
water supplies.
Cadmium
Cadmium has become the most recent and perhaps the most
acute menace among the widely used heavy metals. A great amount
of current research is being conducted regarding the fate and
distribution of cadmium to the environment.
Nearly all this literature concerns the quantification of
cadmium in wastewater and sludges, and the effects of disposal
to land and water systems. However, there is little information
available concerning the direct health hazards of cadmium present
in wastewater and water supplies. The average American citizen's
daily intake of cadmium from foods and water supplies is
estimated to be between 0.02 and 0.1 mg/d. The oral dose of
cadmium producing toxicity is about 3 mg, but its fatal dose is
not known. The whole body half-life of cadmium is 25 years
(Table 97).
Circumstantial evidence appeared to point to some link
between trace metals of cadmium and hypertension. Recent studies,
however (615), have disagreed with this finding, and the general
consensus now is that there is no link between cadmium ingestion
and hypertension. Inhalation of tobacco smoke is a major source
of cadmium accumulation in man. Only about 5 percent of the
cadmium ingested through food or drink is absorbed by the body,
while 10 percent to perhaps as much as 50 percent of inhaled
cadmium is retained (615).
Cadmium tends to accumulate in liver and kidney tissues
because of its very long biological half-life in man (estimates
238
-------
range from 10 to 25 yr, compared with about 70 days for methyl
mercury). Excessive levels in the kidney cortex (over 200 mg/g
wet weight) results in proteinuria. Therefore, the cadmium con-
centration in water must be kept low (615). The Environmental
Protection Agency (EPA) in its 1975 Interim Primary Drinking
Water Standards set a mandatory limit of 0.010 mg/£ for cadmium
concentrations in drinking water; the World Health Organization
set a limit of 0.05 mg/8, . The results of a U.S. Geological
Survey investigation of 720 waterways showed that 4 percent had
concentrations above EPA standards (423).
Cadmium has reportedly caused a number of deaths from oral
ingestion of the metal in food or water. For example, Japanese
people living along the Jintsu River suffered for years from an
unknown malady characterized by kidney malfunction, a drop in
the phosphate level of the blood serum, loss of minerals from
the bones, and osteomalcia resulting in bone fractures causing
intense pain. One of several causes of the malady implicated
was a cadmium, zinc, and lead mine that was discharging wastewater
into the river. The disease, known as i tai i tai, was contracted
either by drinking water from the river or by eating rice that
had accumulated the metal from irrigation water (123). In
another situation, there was an outbreak of acute gastroenteritis
in 13 children who drank orange soda contaminated with cadmium
at a concentration of 16 mg/S, . The contamination was caused
by the orange soda coming in contact with the soldered joints
in the tank of the soft drink machine (57, 60).
Chromium
Chromium, which exists in various oxidation states (+2+3
and +6), appears to be most toxic to man as the hexavalent
chromium ion. The fatal dose of a soluble chromate such as
potassium chromate, potassium bichromate, or chromic acid is
approximately 5 g. Acute poisoning from ingestion is manifested
by dizziness, intense thirst, abdominal pain, vomiting, shock,
oliguria (scanty urination), or anuria. Hemorraghic nephritis
occurs, and death is from uremia.
Repeated skin contact with chromium leads to incapacitating
eczematous dermatitis with edema and slowly healing ulceration.
Breathing chromium fumes over long periods of time causes pain-
less ulceration, bleeding, and perforation of the nasal septum
accompanied by a foul nasal discharge (181).
Whether chromium is carcinogenic is questionable at this
time. However, the incidence of lung r"ncer in ^ork^r? exposed
to dusty chromite, chromic oxide, and chromium ores is reported
to be up to 15 times the normal rate (181).
239
-------
Experiments on rats showed no toxic response from
drinking water containing 0.45 to 25 mg/£ in chromate and
chromium ion form (408)-
Although a potential health hazard exists, evidence of
health problems resulting from chromium present in waste-
waters is lacking in the literature.
Arsenic
Arsenic is widely distributed in nature. It is present
in toxic concentrations in many water supplies: cattle in
New Zealand have died from drinking water containing natural
arsenic, and there are several areas of the world where there
is a high incidence of skin cancer among people drinking well
water that contains natural arsenic (423). In 1971 the U.S.
Geological Survey found that 2 percent of the samples drawn
from 720 waterways were above their standard of 0.05 ppm for
arsenic.
Before the advent of modern insecticides, arsenic com-
pounds were widely used to treat food crops. Although arsenic
can stimulate plant growth in very low concentrations, in
excessive quantities, as little as 1 ppm of arsenic trio-
xide arsenic can be injurious. Organic arsenicals, such as
arsphenamine and dimethylarsinic acid, release arsenic
slowly and are less likely to cause acute poisoning. But
arsenic accumulates in the body, so decreasingly small doses
can ba lethal. Repeated or prolonged intake has a cumulative
to.xic effect, presumably caused by the arsenic combining with
sulfhydryl (-SH) enzymes and interfering with cellular
metabolism.
Chronic poisoning from ingestion or inhalation of
arsenic can cause anemia, weight loss, polyneuritis, optic
neuritis, dermatitis, cirrhosis of the liver, abdominal cramps,
chronic nephritis, and cardiac failure (181).
Arsenic is suspected to be carcinogenic but not tumori-
genic (29, 340, 363.)- Chronic exposure to arsenic-contaminated
water of 0.3 mg/£ is also suspected to be related to the
increased incidence of hyperkeratosis (hypertrophy of the
horny layer of the epidermis) and skin cancer ; chronic
exposure at levels of 0.8 mg/l may be related to gangrene of
the lower 1 imbs (265 ).
Arsenic is one of the impurities in mineral phosphate
deposits, a source of commercial water softeners. Concen-
trations of 10 to 70 ppm of arsenic have been detected 1n
several common household detergents. Baby rash, hand rash,
skin eruptions, and other types of dermatitis allergies are
240
-------
associated with arsenic in detergents. Much of the sewage
containing such detergents is dumped into waterways (423).
There is a danger that arsenic in laundry water may be
absorbed through unbroken skin.
The principal oxidation states of arsenic are +3 and +5.
In the +3 state, arsenic forms arsenious oxide; in the +5
state, arsenious acid; and in the -3 state, arsine gas.
The fatal dose of arsenic trioxide is about 20 mg. Arsenic
poisoning is manifested by gastrointestinal disturbances;
death is due to circulatory failure as a result of hemolysis
(destruction of the red blood cells).
Copper
The biological properties of copper are such that it is
a useful biocide, especially as an algicide. Various salts
of copper (one of the most common being copper sulfate -
CuS04) are used as astringents, deodorants, and antiseptics.
These salts are all water soluble, and their protein-
precipitating characteristics form the basis of their astrin-
gent and antiseptic effects. The copper mined in the United
States for these effects alone amounts to some 15 million
Ib/yr and accounts for about 40 percent of all chemical uses
of the metal.
Trace amounts of copper are essential for normal
metabolism, and relatively large concentrations can be
tolerated by most animals including vertebrates. The effect
of copper on aquatic organisms varies greatly; microorganisms
including algae, are highly susceptible.
Small quantities of copper are not considered toxic,
but higher concentrations are known to cause vomiting and
liver damage (672). Fatalities have been reported following
the ingestion of 10 g of zinc or copper sulfate 0.81 ). An
outbreak of acute copper poisoning occurred in a school in
Mesa, Arizona. The outbreak began 10 min after the students
drank an orange-flavored drink that had been kept in a brass
container for 17 hr (57). An 8-oz glass of the drink
contained 8.5 mg of copper.
Selenium
Selenium is an excellent example of the fine balance
that can occur in nature between the beneficial and injurious
effects of a natural substance. An essential micronutrient
for some plants, selenium is one of the most toxic substances
to occur naturally in the environment; concentrations only
slightly above those needed for growth of plants may be
poisonous to animals. A selenium compound that was used to
241
-------
kill insect pests in fruit orchards left a residue in the
fruit. Cattle that were feeding on this fruit contracted
a chronic form of livestock poisoning called alkali disease.
Ingestion of forage containing about 25 ppm can cause this
disease when the forage is eaten for several weeks or months
(423).
As long ago as 1936, inhabitants of seleniferous areas
of South Dakota and Nebraska complained of gastrointestinal
symptoms and were found to excrete large quantities of selenium
in their urine (423). There is also a report of selenium
toxicity from a three-month exposure to well water containing
9 mg/£ of selenium.
The American Conference of Governmental Industrial
Hygienists recommends a selenium limit of 0.2 mg/cu m in
air and 0.01 ppm in water.
Beryl 1ium
Although the fatal dosage of beryllium is not known,
in 1971 the EPA placed beryllium on the list of hazardous
pollutants. From 1941 to 1967, 760 cases of berylliosis
were recorded (181).
Soluble beryllium salts are irritating to the skin and
mucous membranes, and induce acutepneumonitis with pulmonary
edema. At least part of the changes present in acute
pneumonitis and berylliosis (chronic pulmonary granulomatosis)
develop from hypersensitivity to beryllium in the tissues.
Weight loss and marked dyspnea, which are symptoms of
berylliosis, begin 3 months to 11 years after the first ex-
posure (inhalation). Eczematous dermatitis with a maculopop-
ular, erythematous visicular rash appears in a large percentage
of workers exposed to beryllium dusts.
Barium
Absorbable salts of barium, such as the carbonate,
hydroxide, or chloride, are used in pesticides; the sulfide
is sometimes used in depilatories for external application.
A soluble barium salt such as the carbonate or hydroxide may
be present as a contaminant in the insoluble barium sulfate
used as a radiopaque contrast medium.
The fatal dose of absorbed barium is approximately 1 g.
The principal manifestations of barium poisoning are tremors
and convulsions. Barium presumably induces a change in
permeability or polarization of the cellular membrane that
results in stimulation of all cells indiscriminantly (423).
242
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Other Elements
Antimony will be considered a potential hazard if levels
of the element increase. It is present chiefly in industrial
wastes, typesetting metal, pewter, and enamel ware. Antimony
is suspected to cause a shortened life-span and heart
disease in rats (423) .
Metal alloys and smoke suppresant in power plants are
the major sources of manganese as a pollutant. Although
manganese in trace amounts is an essential element to man,
increased levels may imperil health. The findings in one
death - suspected to be caused by the ingestion of manganese-
contaminated drinking water - were atrophy (a wasting of the
tissues) and disappearances of cells of the globus pallidus
(in the brain). Experimental animals show inflammatory
changes in both gray and white matter (423).
BIOCIDAL CONTAMINANTS
There is significant information in the literature^
concerning biocidal contaminants, their chemical and physical
characteristics, toxicology, analytical chemistry, and
impacts on health and the environment. In both chemical and
medical literature, hundreds of cases of acute poisoning
resulting directly or indirectly from such pesticides have
been reported. Table 98 summarizes the various levels at which
fatal dose, chronic poisoning, and acute poisoning occur.
Chlorinated Hydrocarbons
Because of their persistence and nondegradational
characteristics, many of the relatively less toxic chlorinated
hydrocarbons, such as DDT, aldrin, and dieldrin, have been
banned and are being replaced by highly toxic but less per-
sistent organophosphorus pesticides. The U.S. EPA is pre-
sently conducting a program to identify new, less harmful
pesticides that can act as substitutes for those causing
the problems.
This decision to remove aldrin and dieldrin from the
market has been highly criticized. The idea that these com-
pounds pose "an unreasonable risk of cancer" is based on the
presence of tumors in the livers of mice that were given food
containing aldrin and dieldrin; some of these tumors metasta-
sized to the lungs. However, it has been noted that similar
tumors can be produced by other compounds, such as DDT and
phenobarbi tal , and can occur in mice on normal diets.
There is, then, some question as to whether the production
of tumors in the livers of mice given aldrin or dieldrin is
a reliable indicator of a hazard to man. The general dietary
intake of all major pesticides except aldrin and dieldrin
243
-------
Dieldrin
ro
Lindane
(Benzene
hexachloride)
Malathion
Parthione
TABLE 98 . BIOCIDES IN THE ENVIRONMENT AND THEIR TOXICITY*
Biocide LD5Q (oral)
mg/kg
DDT Rat 285
Rabbit 325
Fatal Doses
(g/kg)
0.4
Chronic
Poisoning
Not substantiated.
Having 648 ppra in
their body re-
mained well .
Acute
Poisoning
Severe vomiting within
30 min to 1 hr of 5 g.
Weakness and numbness of
the extremities. Appre-
hension and excitement
are marked.
Rat 60
Dog 68
Rabbit 45
Rat 135
Dog 120
Rabbit 130
Rat 2500
Rat 4
0.07
0.6
0.86
0.0014
Not been estab-
lished in man.
Impair liver func-
tion in animals,
occasional epilep-
tiform convulsions,
In animals, liver
necrosis.
In animals, colin-
esterase levels of
red blood cells
and plasma are re-
duced markedly.
Not established
in man.
Hype r ex c i ta b i 1 i ty,
tremors, ataxia, con-
vulsions.
Vomiting and diarrhea,
convulsions, circulatory
failure.
Headache, tremors,
nausea, abdominal cramps,
diarrhea, coma, heat
block.
Similar to those of
malathione, but more
severe and fatal.
-------
ro
TABLE 98 . (.continued)
Biocide ID (oral )
mg/kg
2, 4-D Mouse 375
2, 4, 5-T Rat 300
Dog 100
Fatal Doses
(g/kg)
0.7
0.6
Chronic
Poisoning
Weakness, fall of
blood pressure,
muscle damage.
Similar to 2, 4-D
Acute
Poisoning
Burning pain, painful
and tender muscle, fever,
paralysis, irreversible
fall of blood pressure.
Similar to 2, 4-D.
Data primarily from Sunshine (626), Dreisbach (181), and McKee and Wolfe (436).
-------
is well below the allowable standards that were established
in 1972 by the World Health Organization Council on Environ-
mental Quality. Much of the DDT uptake (about 85 to 90
percent) comes from food; the remainder comes from air,
water, aerosols, cosmetics, and clothing.
Because of DDT's extremely low solubility in water
(about 2 ppb), the body, which is essentially a water system,
cannot handle the liquid soluble substance and deposits it
in fat. Quantities of DDT and other related pesticides do
not appear to build up continuously; instead, the pesticides
reach a plateau or steady state (storage equilibrium) at
which they are being excreted and degraded at levels equal
to their intake. Children may take 5 to 10 yr to reach
storage equilibrium. Little is really known about these
levels, which undoubtedly vary with different pesticides,
exposure, intake conditions, and individuals.
Of real concern are the possible effects of long-term
exposure to low levels of DDT and other pesticides. Some
sublethal effects have been observed in animals (cellular
changes in liver tissue and other physiological and histologi-
cal effects); however, these effects cannot be extrapolated
to man. Of course, there is still the suspicion that DDT
might eventually cause damage to human physiology. It has
been suggested, for instance, that long-term exposure to
low levels of pesticides may cause cancer. Research
neither supports nor contradicts this possibility, because
it is difficult to control or document experiments on humans
over a longer period of time.
Based on animal experiments, the average lethal amount
of DDT is a single dose of about 8,000 to 14,000 mg/150-lb
person, although quantities as high as 109 ppm have been
found in sampling a general population. A study was conducted
of persons accidentally or violently killed in Dade County,
Florida, from 1965 to 1967. The average concentration of
DDT in the fat of the bodies ranged from 5 to 22 ppm; there
was more in adults than in children, more in nonwhites than
in whi tes.
Because the use of chlorinated hydrocarbon pesticides
has been sharply curtailed, it is therefore expected that
smaller quantities of DDT are being ingested and that
residues in human fat will decline. However, the average
value of DDT, DDE, and isomers in human fat samples in India
was 21.8 +_ 2.9 mg/kg in 1973 and 24.3 mg/kg in 1965. This
would seem to indicate that the DDT storage status had not
undergone any significant change in those years.
246
-------
A comparative study was performed of DDT and its
derivatives in human blood samples. The study was conducted
in two areas of Ontario where DDT has been used in large
amounts. The mean values of total DDT in the adipose tissue
and blood samples were found to be 5.83 and 0.032 ppm,
respectively. There was a significant correlation between
total DDT in the fat and blood, but there was no evidence
of any adverse effects of DDT on either of the populations
(78).
In another study, tap water samples collected in the
Washington, D.C., area before treatment showed the presence
of DDT (0.17 mg/£), TDE (0.27 mg/£), and DDT-derived compounds
(.15 mg/£); no evidence of these compounds was found after
treatment.
The EPA's ban on DDT has been modified since the incep-
tion of the pesticide in 1972. In 1974, DDT was used against
the tussock moth in northwestern forests and against the pea
leaf weevil in Washington and Idaho. The EPA, however, states
that DDT will be used only against pests that cannot be
controlled by other means and that will do economic damage
or threaten human health or safety. Also, despite the
suspension of aldrin and dieldrin, the EPA will permit their
use against termites and clothes moths, under certain circum-
stances.
The toxic effects of carbaryl , which is used against
DDT-resistant lice, were found to be minimal at the levels
of 75 mg/l (135).
The residues of mirex - a chemical which is used to
control the imported fire ant - were discovered in the
fatty tissue of six persons from 1971 to 1972. It was con-
cluded that the residues came from routes other than direct
pest icide usage (478).
The maximum allowable concentration of most of the
pesticides (as determined by biological tests) lies below
l'mg/i, but is as low as about 0.01 mg/l for such preparations
as atrazine, malathion, and thiometon(522).
Workers occupationally exposed - through manufacturing
processes - to aldrin, dieldrin, endrin, and telodrin
(isobenzan) for up to 15 yr were studied by Versteeg and
Jugar (622). No persistent adverse effects on health were
observed in 52 workers who had left the company and were
traced. The average pesticide exposure in this group of
workers was 6.6 yr, and an average of 7.4 yr had elapsed
since exposure. No hepatic disease or convulsions occurred,
and no new gases of malignant disease developed. Most of
the workers experienced no unusual illnesses.
247
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Exogenous leukemogenic agents such as pesticides (DDT,
lindane, organophosphates) are being considered as potentially
contributory etiological factors that may activate a latent
leukemia virus in certain cells (617).
Organophosphorus Pesticides
The organophosphates attack the neural transmission
system of mammals and arthropods and thus interfere with
the function of the target organs. Especially active are
those organophosphates that function by inhibiting carboxylic
ester hydroxylases (including acetylcholinesterase, which
is present in human erythrocytes, nerves, and skeletal
muscle; and cholinesterase, which is present in human
plasma and in the liver). Miosis (contraction of the pupil),
is found in about 90 percent of the patients with moderately
severe or severe cases of organophosphate poisoning (704).
Tamura et al. (634) conducted a statistical and
epidemiologic investigation of the relationship
between the changes in the use of organophosphorus insecti-
cides and the recent increase in cases of myopia in 40,000
Japanese children from 1957 to 1973. The study showed that
in the year following any period when large amounts of
organophosphorus insecticides were used, the morbidity from
myopia in school children increased rapidly; conversely,
decreased use of the insecticides resulted in decreased
morbidity. This it appears that the recent increase in
myopia in school children was due, at least in part, to
chronic intoxication of organophosphorus insecticides (634).
Pediatric hazards associated with organophosphates are
often reported (424). Signs of toxicity are overaction of
the parasympathetic nervous system, nausea, vomiting, diarrhea,
sweating, and abdominal cramps. Large doses may lead to
muscular paralysis and death from respiratory failure (424).
Because organophosphorus pesticides are readily absorbed
through the skin, as well as by ingestion and inhalation,
these pesticides present a particular hazard to agricultural.
workers who engage in mixing, loading, and applying the con-
centrated materials (605).
The incidence of organophosphorus insecticide poisoning
varies considerably throughout the world. During 17 yr in
Japan there were 19,000 cases of organophosphorus poisoning
reported, resulting in more than 9,000 deaths. By contrast,
during 17 yr in Great Britain there were only five deaths
reported from this poisoning (657). Increased chromosome
aberrations were observed in patients suffering acute
organic phosphate insecticide intoxication. The frequency
of stable chromosome aberrations showed a significant increase
248
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with malathion, trichlorfon, mevinphos, and methyl parathion;
malathion induced an outstandingly high number of structural
chromosome aberrations. Patients less seriously intoxi-
cated suffered milder chromosome alterations. Even
in the absence of clinical signs of organophosphate poison-
ing by dichlorvos at low levels, the cholin esterase
values were much lower than those of a nonworker control
population. The decrease in enzyme levels was significantly
correlated with subjective health complaints: sore throat
and loss of memory (43).
Herbicides
Today over 40 weed killers are available, but the most
widely used are 2, 4-D (2, 4 - dichlorophenoxyacetic acid)
and 2, 4, 5-T (2, 4, 5 - trichlorophenoxyacetic acid). In
general, these chemicals are rarely lethal to humans or
animals, do not persist for long periods of time in the
environment, and do not build up in the food chain.
During the Vietnam war, South Vietnam suffered massive
military herbicide spraying. It has been estimated that at
least one-third of the timber forests was destroyed, as
well as 10 percent of all cultivated land and at least 25
percent of the coastal Mangrove forests, which are the
breeding or nursery grounds for most offshore fish and
crustaceans (686). However, there was no evidence in
Vietnamese hospital records that were examined by Thimann
(642) that birth defects could be attributed to the herbicide
spraying.
Humans are exposed minimally to the phenoxy herbicides
through food; air and water are the primary sources of
exposure to these herbicides. On the basis of air samples
collected from wheat-growing areas in the state of Washing-
ton, it was estimated that an average person would be ex-
posed to 1.8 mg of phenoxy herbicide/day. Rain and wind carry
the herbicides into water(114). Workmen who were engaged
in the manufacture of herbicides were examined; the clinical
results were compared to those of a control population that
was not exposed to the 2, 4-D or 2, 4, 5-T. No meaningful
differences were obtained; moreover, there were no chromosomal
effects (114).
In the fall of 1969, the National Institute of Cancer
reported that 2, 4, 5-T was teratogenic and was responsible
for fetal toxicity at levels of 27 ^ 8 ppm. The manufacturer
claimed that this herbicide was not teratogenic; that the
fetal toxicity was caused by 2, 3, 7, 8-tetrachlorodibenzo-p-
dioxin, known as dioxin (333).
249
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At the dose level of 100 mg/kg/day of silvex, there
were no effects on either the dams or fetuses of rats.
Similar observations were also made with picloram. Picloram,
however, is much more persistent in soil than the other com-
pounds. Unlike DDT, it forms soluble salts and does not con-
centrate in fat; in addition, the toxicity of picloram is
very low when compared to that of most other herbicides (333) .
The widespread use of phenoxy herbicides has produced
no demonstrable evidence of potential harm to man. The
herbicides used most widely (2, 4-D and 2, 4, 5-T) are
degraded to nontoxic components and do not bioconcentrate
(653).
An epidemiological investigation was made of tumor
incidence and mortality in Swedish railway workers exposed
to various herbicides. Among workers exposed to amitrole
(3-amino-l, 2, 4-triazole), tumor incidence and mortality were
significantly increased and were slightly dose related. Nearly
normal conditions were found in those exposed to phenoxy
acids. Animal experiments suggest that amitrole may produce
malignant tumors in several different organs, but tumors
of the thyroid and liver have received the most attention
(23).
To receive a letal dose of 2, 4, 5-T, a 125-lb woman
would have to eat the equivalent of her body weight of material
containing 380 ppm of the herbicide (based on the acute oral
toxicity expressed in mg/kg). Both 2, 4, 5-T and DDT in
technical form are relatively nontoxic on skin contact (3,800
mg/kg for 2, 4, 5-T and 2,500 mg/kg for DDT). There have been
no human deaths and remarkably few human illnesses from the
agricultural or public health uses of either of these chemicals.
A no-effect level of 50 mg/kg/day of 2, 4, 5-T containing less
than 1 ppm dioxins is proposed as providing ample protection
for human embryos (114).
The first recognized incident in which significant
poisoning resulted from the improper disposal of waste
residues containing TCDD (tetrachlorodibenzodioxin) was in
eastern Missouri. In this incident, a salvage oil company
sprayed waste-oil sludge on an arena at a horse-breeding
farm, to control dust. Birds, cats, dogs, and rodents were
killed; 62 out of 85 horses became ill, and 48 died. The
horses had been exposed to the arena in the summer of 1971,
and they continued to die as late as January 1974. The horses
showed chronic weight loss, loss of hair, skin lesions,
dependent edema, intestinal colic, dark urine, gross hematuria
(the passage of blood in the urine), conjunctivitis, joint
stiffness, and laminitis (inflammation of one side of the
neural arch of a vertebra). In addition, the horses' feet
250
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were inflamed. Human illness, although less severe, included
one case of hemorrahagic cystitis in a 6-yr-old girl who
played in the arena. The soil of the arena contained 3.18
to 3.3 percent TCDD by weight and 2, 4, 5-tri chlorophenol
(TCP) and related chemicals (662).
Paraquat, a widely used bipyridyl herbicide, produces
a low-dose, chronic illness in rats, primarily manifested
by pulmonary fibrosis (216). Paraquat is also known to
cause severe lung damage in rats, leading to death.
Although it causes proliferation of fibroblasts, no
carcinogenic action has been demonstrated. Taken orally,
paraquat causes ulceration in the digestive tract, diarrhea
and vomiting, renal damage, and jaundice.
Pesticidal Viruses
Tinsley and Melnick(645), found some antibodies that
reacted with insect viruses in domestic and wild animals and
in several laboratory workers handling insect viruses.
There is always a possibility that changes in the patho-
genicity and specificity of pesticidal insect viruses could
occur, causing a wider spectrum of host involvement. No
collaborative research programs on the in vitro specificity
of insect viruses were recommended (645).
Fungicides
In Iraq during a two-month period, 6,530 poisoning
victims were hospitalized, and 459 hospital deaths occurred.
The source of the poisoning was found to be homemade bread
prepared from seed wheat treated with methyl mercurial
fungicides (634). In another case, diphenyl (or bi.phenyl )
poisoning from fungicide in a Finnish paper mill was reported
by Seppalainen and Hakkinen(573). Workers were employed in
areas of the mill where the average concentration of. diphenyl
measured in the air varied from 0.6 to 123.0 mg/m^. The
workers developed EEC abnormalities that were compatible with
generalized cerebral disturbance (573).
Polychlorinated Biphenyls (PCB's)
Relatively high concentrations of a group of widely used
industrial chemicals known as PCB's have been found in fish,
birds, and man. The widespread presence of these PCB's has
tagged them,like DDT, as truly global pollutants. In fact,
it has been speculated that sunlight might convert DDT to
PCB's. PCB's are insoluble in water, soluble in fats and
oils, and very resistant to chemical and biological degrada-
tion. Due to their solubility, PCB's accumulate in the
environment, especially in aquatic organisms and birds (in
251
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which cumulation factors up to one billion may be reached)
PCB's, like DDT, can inhibit photosynthesis of marine
phytoplankton and can kill shrimp, trout, minks, and birds
PCB's may be twice as effective as DDT in causing thinning'of
bird eggshells.
In 1968, over 1,000 people in Japan suffered from a
skin disease and from liver damage caused by rice oils. The
oil was heavily contaminated with PCB's; however, these
effects were not due to the PCB's but to a highly poisonous
contaminant - chlorinated dibenzofurans. This contaminant
is found in some PCB's manufactured in other countries.
To date limited study in this area indicates that
uncontaminated PCB's have a very low toxicity to man.
According to the Food and Drug Administration, the average
PCB concentration in a normal American diet is only about
10 percent of the strict safety levels set in 1971 for food,
food packaging materials, and animal feeds.
SYNTHETIC/ORGANIC CONTAMINANTS
Recently diverse compounds identified in water supplies
drawn from the Mississippi River have been discovered in
the blood serum of local residents using the water supply.
This has created great concern over chemicals found in
drinking water. The presence of small amounts of synthetic/
organic chemicals in treated reclaimed water has been
recognized as a potential health hazard.
The list of compounds identified in drinking waters is
rapidly growing larger. This is due primarily to the
continual introduction of new chemicals but also to the
development of sensitive analytical techniques that measure
trace quantities of the chemicals. There is very little
evidence available concerning the relation between the
presence of these compounds in water and human disease.
Information on classical acute health effects of relatively
toxic chemicals can be obtained from physicians' manuals.
However, knowledge of the chronic health effects associated
with long-term exposure to low-level concentrations of
chemical substances is not well documented. The possibility
that cancer may result from long-term exposure to low con-
centrations of carcinogens is of utmost concern.
Carbon-Chloroform Extractables (CCE) and Carbon Alcohol
Extractables (CAET '
The Committee on Water Quality Criteria (672) suggested
that absorbable organic carbon in public water supply sources
should not exceed the carbon chloroform extractables (CCE)
252
-------
level of 0.7 mg/£. (No level has been established for carbon
alcohol extractables - CAE). The establishment of this level
was based upon the adverse physiological effects of CCE as well
as aesthetic considerations.
To date, laboratory testing of the epidemiological and
pathological effects of trace organics has been restricted
to mice and fish. Hueper and Payne (306) conducted a study of
mice that were exposed subcutaneously, cutaneously, and orally
to extracts of CCE and CAE obtained from both raw and finished
water supplies. Results of this study indicated that these
extracts had a potential for carcinogenicity (see Table 99).
The cutaneous dose used in the experiment was one drop of extract
every 2 weeks for 56 weeks with 72 mice; the subcutaneous dose
was 2 to 4 mg every 2 weeks for 56 weeks with 72 mice; and the
oral dose administered as 2 percent of the raw powdered food
was eaten ad libitum by the animals for a 13-month period during
the study. The control group consisted of 40 unexposed mice.
No tumors were observed among the 40 mice in the control
group or among those exposed orally. Carcinogenic effects
in subcutaneous and cutaneous groups included one papilloma
(a circumscribed overgrowth of the papilla) of the bladder;
four spindle-cell sarcoma (fusiform cell tumor) at the site
of subcutaneous injection; and leukemia, lymphoma, or
reticulum-cel1 sarcoma of the liver in all other instances.
However, it is very difficult to extrapolate the experimental
data of animals to humans. Thus, the question still remains
as to whether such extracts would cause similar abnormalities
in humans.
Another experiment was conducted to investigate the
toxicity of CCE and CAE from processed water supplies (187) .
A total of 5 mg of either CCE or CAE was introduced sub-
cutaneously during the first 20 days after birth of the
test mice. No tumors were found to be induced during the
period, but varied death rates of the test animals were ob-
served. The studies were conducted over a 1-yr period using
New Orleans drinking water supplies (187).
Organohalides
Occurrence and formation of organohalides such as
CHC13, CHC^Br, CHCIB^, and CHBr3 were reported when water
containing organic substances was chlorinated (41, 554).
Of the haloforms, chloroform (CHC13) was reported as the
predominant organohalide, with concentrations ranging from
54 yg/£ to 150 yg/£. The level of risk for chloroform -
estimated from consideration of the worst case and for the
expected cancer site, such as the liver - might be ex-
trapolated to account for up to 40 percent of the observed
liver cancer. The toxicity of chloroform has been well
demonstrated in lethal-dose studies.
253
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TABLE 99 . SUMMARY OF RESULTS OF INTRODUCING CCE AND CAE
FROM RAW AND FINISHED WATER INTO MICE (306)
ro
tn
f*
Route of
Exposure
Subcutaneous
Cutaneous
Oral
Number of Tumors Produced/Animal Exoosed
Water Source
Raw Finished
CCE CAE CCE CAE
5/72 1/72 2/72 1/72
2/72 1/72 0/72 0/72
"* - 0/40
-M ~-
* No test.
-------
An LD50 (lethal dose - 50 percent) value ranging from 89 to
35 mg/kg was observed by Tardiff and Deinzer (636) when CCE
obtained from the Kanawha River in West Virginia was introduced
into mice via an interperitoneal route. The differences among
these LDso values was shown to be due to the amount of chloroform
present in the extract, indicating the toxicity of chloroform.
The CAE obtained from the same river showed an LDso of 84 mg/kg.
The LD5o for the concentrated organics from Cincinnati tap water
was shown to be 65 to 290 mg/kg.
The same authors also reported the identification of 60
compounds from drinking water. Of the compounds, 1 was classified
as nontoxic; 14, moderately toxic; 16, very toxic; 2, extremely
toxic; and 27, unknown (74). However, it is difficult at this
time to determine the relationships of the toxicities of these
compounds in humans to the level of the compounds present in
water and wastewater.
Careful interpretation of the toxicity data, such as
the 1050 value obtained from concentrated extracts, is
necessary when these values are to be used to set toxicity
levels in drinking water.
Polynuclear Aromatic Hydrocarbons (PAH)
Occurrence, formation, concentration, activity, carcin-
ogenicity, and degradation of polynuclear aromatic hydro-
carbons (PAH) in water are well documented (17).
Of the PAH, 3, 4-benzpyrene has been generally recognized
as the most potent carcinogen. Minimal carcinogenic doses of
three of the most potent hydrocarbons in susceptible experi-
mental animals is shown in TablelOO .
TABLE 100 . THE MINIMAL CARCINOGENIC DOSE FOR
THREE OF THE MOST POTENT CARCINOGENIC HYDROCARBONS
IN SUSCEPTIBLE EXPERIMENTAL ANIMALS (716)
Least Amount which
Carcinogen
3,4 - Benzpyrene
3,4 - Benzpyrene
1,2,5,6 - Dibenzanthracene
20 - Methyl cholanthrene
Animal
Mouse
Rat
Mouse
Mouse
Rat
Caused Cancer*
4.0 yg
50.0 yg
2.5 yg
4.5 yg
20.0 U
-------
Miscellaneous Organic Compounds
A preliminary experiment was designed to study the
toxicity of organic compounds present in a secondary treat-
ment plant effluent. Rats were supplied with filter-
sterilized effluent from an activated sludge plant as the
sole source of drinking water. Two of the 10 rats developed
massive tumors. Also, the exposed female rats developed
significantly smaller adrenal glands than the control rats
that were provided with the local water supply (496).
An epidemiologic study on the toxicity of compounds
present in drinking water was cited by Andelman and Suess
(17). This study indicated fewer cancer mortalities in a
London borough that was supplied with well water than in
boroughs supplied with river water. This could mean that
the river water receives more carcinogenic waste material.
Similar findings reported by Tromp (650) showed that
areas using municipal water systems had Tower cancer death
rates than those using other systems. However, the cancer
death rate was higher among areas that received municipal
water from a river than among those that received municipal
water from wells.
When other factors such as food, air quality, and
individual habits (i.e., cigarette smoking) are considered,
the importance of trace carcinogens in water supplies may
not be significant. However, several observations have been
made correlating water supply quality and cancer incidence.
For example, Talbot and Harris (633) established
a correlation between cancer mortality in white males and
water supply source, between mortality and urbanization, and
between mortality and income. When occupational variables
are not considered, lung cancer mortality rates were found
to be correlated with surface water sources, but there were
no correlations found in other cancers.
Halogenated Hydrocarbons
In a study that was designed to investigate the correla-
tion between levels of halogenated hydrocarbons in New
Orleans drinking water and levels of halogenated hydro-
carbons in blood plasma of individuals drinking the water,
13 halogenated hydrocarbons were isolated. Researchers also
detected the presence of carbon tetrachloride and tetra-
chloroethylene (2 of the 13 compounds) in the pooled sera
of eight people. It is probable that biomagnification was
involved if the chemicals in the plasma originated from the
drinking water (180).
256
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Low Molecular Sulfurated Hydrocarbons
A case history study of the waterborne goitrogens and their
role in the etiology of endemic goiter was recently reported from
Colombia, South America (229). The potential presence of low
molecular weight compounds (less than 220), such as sulfurated
hydrocarbons in water and wastewater, received careful evaluation.
The compounds (sulfurated hydrocarbons) were known to be related
to the high incidence of goiter among children and were regarded
as waterborne goitrogens. The study also reported a 10-fold
increase in cancer of the thyroid where endemic goiter was
observed (229).
BIOLOGICAL CONTAMINANTS
Epidemics of waterborne diseases have largely been elimi-
nated, due mainly to the advancement of sanitary engineering,
enforcement of public health regulations, and preventive medical
practices; however, waterborne disease data from the last three
decades indicate that outbreaks are no longer on the decline in
the United States. During the 25-yr period from 1946 to 1970,
there were 358 recognized outbreaks (72,358 individuals involved)
of disease or chemical poisoning attributed to contaminated
drinking water (145, 220).
According to the reports of the Center for Disease Control
(221) during the past four years (from 1972 to 1975), 105 water-
borne disease outbreaks were reported, involving 22,650 cases.
As shown in Table 101, in 1975, 24 waterborne disease outbreaks
were reported, involving 10,879 cases.
TABLE 101. WATERBORNE DISEASE OUTBREAKS
1972-1975 F AND W (145)
1972 1973 1974 1975 Total
Outbreaks
Cases
29
1,638
24
1,720
28
8,413
24
10,879
105
22,650
Table 102 shows the number of outbreaks and cases by
etiology and type of water system. The category with the most
outbreaks Is acute gastrointestinal illness. This category
includes outbreaks characterized by upper and/or lower gastro-
intestinal symptomatology for which no specific etiologic agent
was identified. In previous years, these outbreaks were
considered sewage poisoning. One outbreak each was caused by
giardiasis, shigellosis, enterotoxigenic E. coli, and hepatitis A.
There were no reported deaths associated wTth waterborne disease
outbreaks in 1975 (221).
257
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Most outbreaks involved semipublic (67 percent) and
municipal (25 percent) water systems; some involved individual
(8 percent) systems. Outbreaks attributed to water from muni-
cipal systems affected an average of 1,218 persons; those
attributed to semipublic systems involved 221 persons; and those
associated with individual water systems affected 13 persons.
Of those 16 outbreaks associated with semipublic water supplies,
11 (69 percent) involved visitors to areas used mostly for
recreational purposes.
TABLE 102. WATERBORNE DISEASE OUTBREAKS, BY ETIOLOGY
AND TYPE OF WATER SYSTEM, 1975 (221)
Municipal Semipublic Individual Total
Outbreaks Cases Outbreaks Cases Outbreaks Cases Outbreak? Cases
Acute gastro- 4 7,300 13 2,460 ~ 17 9,760
intestinal
illness
Chemical 2 11 1 26 3 37
poisoning
Giardiasis ~ 19 1 9
Shigellosis -- 1 56 -- - 1 56
Enterotoxi 1 1,000 -- 1 1,000
genie £._ col i
Hepatitis 1 17 1 17
Total 6 7,311 16 3,542 2 26 24 10,879
The object of this section is to compile a comprehensive
summary of research into the health effects of biological contami-
nants in wastewater treatment. Diseases transmitted by water and
wastewater largely originate in the intestinal discharge of man
and/or animals. These diseases are caused by bacteria, viruses,
fungi, and protozoan and other parasites.
Protozoan and Other Parasites
A number of intestinal parasite infections can be introduced
into man directly from water supplies and indirectly through
wastewater discharges. Under normal conditions, the potable-water
route of infection is quite unimportant. However, the reuse of
treated waste effluents for potable purposes requires that this
problem be reexamined.
Ascariasis (a disease caused by infection with ascaris),
trichuriasis (a disease caused by infection with trichuris), and
258
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hookworm diseases are some of the infections that originate from
direct soil pollution by feces. This pathway has been virtually
eliminated in the United States, due to the introduction of modern
sewage disposal and water supply systems. When there is a break-
down in sanitation, these diseases may reappear (699).
Studies in foreign areas affirm the relative unimportance of
public water supplies as a route of infection for intestinal
parasites. A study by the World Health Organization (WHO) in
Sudan, in which a modern water supply was provided to one test
city, showed that parasitic infections were not decreased. The
study indicated, instead, the need for sanitary waste disposal
facilities. This finding was substantiated by the substitution
of a modern water supply system for an older system in Western
Transvaal. The substitution had no effect on the prevalence
of helminths among the Bantu population studies - children 7 to
16 years (699).
Amoebic dysentery (or amebiasis) appears to be the most
important parasitic disease associated with wastewater in the
United States. It is caused by Entamoeba his to1y t i c a , a protozoan
Today, the prevalence rate of E. histolytica in the general popu-
lation of the United States is considered to be around 3 to 5
percent (383). The prevalence of the intestinal protozoa varies
considerably in different population groups and is generally
correlated with socioeconomic conditions. Higher rates are
found in areas of poor sanitation and in regions without sewage
systems and potable water. Higher rates are also noted in groups
of people with poor personal hygiene (e.g., patients in institu-
tions for the mentally retarded).
The amoeba can form small cysts (5 to 20 ym) with a specific
gravity of about 1.06. Each mature cyst is capable of producing
four motile amoebae. The cysts are resistant to adverse environ-
mental conditions and are excreted with feces into water and/or
remain in the human digestive tract to become vegetative amoebae.
These amoebae multiply and may become invasive, causing erosion
of the superficial mucous membranes. They may eventually invade
the tissue with consequent ulceration.
The vegetative forms do not survive outside the digestive
tract. As with most parasitic diseases, the symptomatology
produced by pathogenic intestinal protozoa is too nonspecific to
enable the physician to make an accurate clinical diagnosis.
In 1974, there were 2,743 reported cases of amebiasis in the
United States (458), because of nonclinical manifestations, the
actual figure is undoubtedly considerably higher.
In an experiment with volunteers, it has been demonstrated
that up to 25 percent could be infected by a dose containing less
than 10 organisms of entamoeba; the remainder required a minimal
dose of 10,000 organisms to become infected. However, as shown
259
-------
in Table 103, the infected volunteers did not manifest any signs
of illness.
Giardia lamblia, a flagellated protozoan of the small
intestine, often implicated epidemiologically with drinking
water is the etiological agent for giardiasis. An outbreak
has recently been reported (460) in Rome, New York, where the
water supply could have been contaminated by untreated human
waste. Another outbreak of giardiasis by G. lamb!ia was reported
in September 1976 in Idaho. The source was purported to be from
untreated surface water of an individual water system (290).
Apparently, the cysts of GL_ lamb!ia survive in water and
remain infective for 16 days. During 1969 to 1973, seven out-
breaks involving 193 people were reported in the United States.
During October 1954 to March 1955, there was a suspected water-
borne outbreak of 50,000 cases of giardiasis in Portland, Oregon.
The outbreak was not reported, because of the failure to isolate
the organism from the suspected water source (451). Epidemic
giardiasis among American travelers to the Soviet Union has been
reported since 1970; the latest outbreak was reported in
October 1975 (460). Sporadic single cases or occurrences of
giardiasis with recent exposure to untreated mountain or pond
water have been noted (457). In an experiment where adult
humans were given challenge doses of Giardia lamblia, 76 to 100
percent infected with a dose containing 10 organisms did not
become ill. Similar results were observed with doses containing
up to a million organisms (see Table 103).
An outbreak of ascariasis occurred after World War I;
one out of every three surgical patients at a hospital in
Le Havre, in the 2 yr following cessation of the war, was found
to have the disease (699). Also, following World War II, a
40 percent incidence of ascariasis was reported in Darmstad
and was attributed to a widespread breakdown of sanitation
practices that occurred in Germany during the latter part of
the war (699).
In moderate climates, the human contribution of ova to
wastewater would appear to be no greater than 10 percent, but
may reach 30 percent in subtropical regions such as the southern
extremities of the United States. The remainder of the ova is
of animal origin. Various authors have reported 59 to 80 worm
eggs/£ sewage (223). The eggs are generally resistant to
environmental conditions, having a thick outer covering to
protect them against desiccation. In one study, 90 percent of
ascaris ova was destroyed after 15 days at 29"C; the ova may
survive for up to 60 days at 40°C (223).
Ova from the giant roundworm Ascari s 1umbri coides, the
pinworm Oxyuris vermicularis. the whipworm Tri churi s ' tri churia_,
the tapeworm Taenia saginata. and possibly the hookworm are
260
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TABLE 103 . CLINICAL RESPONSE OF ADULT HUMANS TO
VARYING CHALLENGE DOSES OF ENTERIC PATHOGENS (88)
ORGANISM
(strain )
Shi gella
dysenteri ae
Challenge doses
10° 101 102 103 104 105 106 107 108 109 1010 1011
(1) (A-l)
(1) (M 131)
Shigella
flexneri (w)
(2a) -
(2a)
Vibrio
cholerae
inaba 569B
(unbuffered)
inaba 569B
(+NaHC03)
ogawa
(+NaHC03)
Salmonel la
(Zermat)vi
(Quailes)
++
++++
++
++
++
-------
TABLE 103. (continued)
ORGANISM
(strain)
Salmonella
new port
Salmonel la
barei 1 ly
Salmonel la
Challenge doses
10° 101 102 103 TO4 105 106 107 108 1Q9 in^O lftll
+ ++
+ ++
anatum(I)
(II)
(HI)
rsa *
ro
Salmonella
meleagridis (I)
(ID
(HI)
*
Salmonella
derby
SalmoneJ la
pul loriTmd)
(II)
(III)
(IV)
-------
ro
TABLE 103. (continued)
ORGANISM
Challenge doses
(strain)
Escheri chia
coli(0111714)
TOt5":B4)
(06:H16)
(0124:K72:H-)
(0143:K?:H-'
(0144:K?:H-
(0148:H28)
Streptococcus
faecali s var.
1iquefaciens
Clostridi urn
perfringens.
type A (Heat-
resistant)
Clostridi um
pjsrf ri nqens
type A^tHeat
sensi tive)
10'
10
10'
TO
10
10
10
10
10
10
Endamoeba
coli
Giardia
Tambli a
-------
TABLE 103. (continued)
ORGANISM
(strain)
Chall
10° 101 TO2 103 104 TO5
enge doses
TO6 107 TO8 TO9
1010 1011
agent
(virus)l ++
++ 2 +++
3 +
Hepatitis
virus A +++
(fecal ++
vi1trates)
de^optng niness? = 26~5°' +++ = 51'75' ++++ ' 76-100 Perce"t of volunteers
* Refeeding trials of volunteers who mo before became infected by the same strain.
** 1,2,3 refers to serial passages of stool filtrates.
( + ). Infections without illness.
1 = cholera-like diarrhea.
-------
reported to be present in wastewater (223). Heavy infestations
of roundworms found in some European cities are related to the
use of night soil, which is also known to be responsible for
about 20 percent of the recurrent infections of amoebiasis and
hookworms (237).
Man is known to be the host and reservoir of A. Tumbricoides.
whose ova are excreted in the faces of infected indTviduals.0~vT
of these intestinal parasites require several days before maturing
to an infective stage. Under the most favorable conditions,
ascarlds require 10 days to mature; trichurids, 21 days; and
hookworms, 6 days. Hence, these parasites are unlikely to pose
health threats if the water is used for drinking, since they would
be eliminated from the human body before maturation. However, use
of such water for food processing, garden watering, or simple
aesthetic activities may require the effective removal or destruc-
tion of the parasites (699).
Free-living nematodes are widely found in municipal water supplies.
Their potential as carriers of enterococci, salmonella, and shigella has
been demonstrated (699). Although free-living nematodes are not important
as health threats in conventional waterworks practice, their significance
in a reclaimed water situation needs evaluation.
Dracontiasis, or guinea worm infection, is a disease
primarily associated with poverty (especially inadequate water
supplies and wastewater treatment), and is common in India and
West Africa. Vector species of Cyclops persisting in ponds
used for drinking water must be controlled (usually by the use
of Abate at a concentration of 1 mg/£).
In summary, it may be stated that a large quantity of a
variety of ova from parasitic worms may be present in wastewater,
and that the ova possess a high degree of resistance to many
environmental stresses.
Fungi
Candida albjcans, a pathogenic, yeastlike fungus, is an
asporogenous (non-spore-forming) yeast that develops pseudohyphae
(a kind of filamentous structure). Large, round, thick-walled
chlamydospores - the morphological characteristic of the genus
Candida - are frequently, though not always, present in waste-
water.
c- albicans has been found in the feces and skin of several
animaV~species other than man. The fungus rarely occurs in
soil. The prevalence of Candida in feces in different regions of
the United States varies from 19.3 to 44.6 percent of the total
population (323). Seventy percent of the inhabitants of Baghdad
have the fungus in their feces. Another important infective
265
-------
area in the human body is the female vagina; 43 percent of the
female population in the United States are carriers (323) .
C. albicans may cause oral thrush, cornea! ulcers, and
other ocular infections. One survey analyzed 20 weekly samples
collected at three stations on the North Shore of Great South
Bay, Long Island. It was reported that the estuarine water
samples contained between 1,000 to 11,000 or more cells/£(323).
These results are shown in Table 104.
TABLE 104. AVERAGE VALUES FOR C. ALBICANS, COLIFORM
AND FECAL COLIFORM COUNTS AND TOC (TOTAL ORGANIC CARBON)
DETERMINATIONS IN THE ESTUARINE WATER SAMPLES,
LONG ISLAND, NEW YORK (323)
Estuari ne
Stations
Station 1
Station 2
Station 3
C. albicans
cells/.£
4,245
4,003
9,555
Col iform
Total
MPN/100 ml
338
298
1,962
Col iform
Fecal
MPN/100 ml
33
12
490.5
TOC
mg/£
8
8.4
8.7
This fungus retained an infectivity and pathogenicity to
mice after it was exposed to sea water for eight weeks (323).
In the open ocean, there is a concentration of 200 to 300 fungal
cells/£; in moderately contaminated beach areas, there are
levels of 10,000 to 20,000 cells/£J and in heavily contaminated
estuaries, up to 100,000 eel ls/£(323) . The overall trend was
a gradual increase in concentrations during summer months, from
June to September, after which the concentration declined (323).
Bacteria
Salmonellosis--
A wide variety of species that are pathogenic to man and
animals belongs to the genus Salmonella. Water and food, as
well as personal contact, are the main routes for transmission
of the species from man to man.
Among the three distinct forms of salmonellosis in man,
typhoid fever - caused by S_^ typhj - is the most severe
enteric fever form, and man is the only host. Salmonella
septicemia, most commonly caused by S. choleraesuis. is
relatively rare. This bacteria is not particularly common in
humans, but has a predilection for swine. Salmonella are most
commonly encountered in acute gastroenteritis. Serotypes (types
based on antibodies) in excess of 1,500 have been identified.
Most, in contrast to S. typhi, are not host specific.
266
-------
The death rate, due to typhoid fever in the United States
in 1900, was 31.3/100,000 population; however, at present, death
due to this disease is practically nonexistent, as shown in
Table 105 (164, 308).
TABLE 105. U.S. MORTALITY FROM SELECTED CAUSES
RELATED TO WATER POLLUTION (164)
Cau
Fyphoi
se
d
of Death
& paratyphoid
1920
7.6
Death
1930 1
4.8
Rate
940
1.1
per 100
1950
0.1
,000
1960
0.0
1967
0.0
fever
Dysentery
Gastritis, duodenitis,
enteritis, & colitis
4.0 2.8 1.9 0.6 0.2 0.1
53.7 26.0 10.3 5.1 4.4 3.8
Relatively few outbreaks of typhoid fever and salmonellosis
associated with drinking water were reported in the United States
during 1971 to 1973(220, 448). The reported isolation rates
for humans in the United States in 1972 was 12.5/100,000; the
fatality rate between 1962 and 1972 was 0.43 percent, mostly
among the very young and very old.
In 1974, 23,833 isolations of salmonella were reported to
the Center for Disease Control, a decrease of 2,855 cases
(10.7 percent) from the previous year. As in 1973, S. typhimurium
(30.8 percent), S. newport (6.9 percent), and S. enteritides
(6.0 percent) were the first, second, and thircTmost commonly
isolated serotypes, respectively ( 563). The annual incidence of
reported human isolations of salmonella has remained relatively
constant since 1963 (563).
The seasonal incidence for the period from 1967 to 1974 shows
a consistent pattern, with the greatest number of isolations
reported in July through November, and the fewest reported in
February through April (563).
The ages of infected persons reveal that 66.8 percent of
the 17,229 isolations was from persons less than 20 yr of age.
Similarly, this age group showed the highest infection incidence
for the years from 1963 through 1973 (563).
Several serotypes (e.g., S. weltevreden
S. os 11o in Hawaii; S. newport and S. javiana
states! have definite regional patterns, for
not clear.
S. panama. and
, 5^_ £
in th
southern
reasons that are
267
-------
from 1962 to 1974, 143 deaths were reported among the 34,291
persons involved in 499 outbreaks. This resulted in a case-
fatality ratio of 0.42 percent.
In 1974, in 18 of the 34 outbreaks of salmonellosis (involv-
ing a total Of 4,011 persons), 5 outbreaks were caused by contami-
nated poultry, 5 by beef or beef products, and 3 by dairy products,
In 6 of these outbreaks, person-to-person transmission was thought
to be responsible; none was reported to be transmitted by water.
In 1§73, 3 typhoid outbreaks (totalling 217 cases) and 1 out-
break of salmonellosis (3 cases) occured in semipublic or
individual water supplies. In 1974, an outbreak involving several
hundred people on a cruise was reported; epidemiologic investiga-
tion failed to clearly implicate either food or water. Three
epidemiologic investigations of turtle-associated salmonellosis
were also found in thfe 1iterature(144).
According to experimental data, the dose required to bring
about human cases of typhoid fever is surprisingly high (300).
Human volunteers were challenged with various doses of
Salmonella typji_j_. The results are summarized in Table 106.
TABLE .ioe. RELATION OF DOSAGE OF
IL. TYPHOSA TO DISEASE (300)
Number of Viabie CellsTotal VolunteersNumber with Disease
S_^ typhosa Challenged
109
lb8
107
105
103
42
9
32
116
14
40 (95%)
8 (89%)
16 (50%)
32 (28%)
0 (-- )
With the salmonella species isolated from spray-dried eggs,
human volunteers were challenged orally; the results are
Summarized in Table 107. Existence of varying degrees of
virulence among the species and strains are shown. Similar
results are shown in Table 103.
268
-------
TABLE 107 . DOSE OF VARIOUS SPECIES AND STRAINS OF
SALMONELLA THAT CAUSED DISEASE IN HUMAN VOLUNTEERS (142)
Salmonella Dose at which 50% or More
Species/Strain Develop Clinical Disease
S. meleagridis I50,000,000
S. meleagridis II 41,000,000
S. meleagridis III >10,000,000
S. anatum I ' 860,000
S. anatum II 67,000,000
S. anatum III 4,700,000
S. newport 1,350,000
S. derby 15,000,000
S. bareilly 1,700,000
S. pullorum I >1 ,795,000,000
S. pullorum II >163,000,000
S. pulloram III >1,295,000,000
S. pullorum IV 1,28(0,000,000
Shigellosis--
Shigella cause bacillary dysentery in man and in higher
apes. Although person-to-person transmission is the predominant
mode of spreading shigellosis, waterborne outbreaks have played
a significant role in the overall epidemiology of the disease
in the United States(579, 612). In 1975, 14,757 shigella
isolations from humans were reported to the Center for Disease
Control (CDC). This was a decrease of 24.0 percent from the
19,420 isolations reported in 1974 (580). Utilizing population
estimates for July 1, 1975, approximately 69.2 isolations were
reported for each million population of the United States in 1975.
Shigella sonnei (60.3 percent ) was the most common etiological
agent in all these cases, followed by S. flexneri (38.2 percent).
Between January 17 and March 15, 1974, approximately 1,200 cases
of acute gastrointestinal illness occurred in Richmond Heights,
Florida. The outbreak was caused by a failure in the chlorination
process of well water, which allowed insufficiently chlorinated
269
-------
water from a contaminated well (located near a church's septic
tank) to be distributed to the community (144).
Most instances of Shigella-induced illnesses reported in the
past several years have involved small wells, temporary break-
downs of chlorination systems in water supply, and swimming in
waters contaminated with sewage. The isolation rate in the United
States is approximately 15/1,000,000 population. Up to 25 per-
cent of adult humans may be infected and show clinical response
to Shigella dysenteriae doses of 10 cells; 25 to 50 percent, to
doses of 100 eel Is; and up to 100 percent, to doses of 10^ cells
(see Table 103). These results indicate that it would take
smaller doses to show clinical response for shigella than it
would take to show response for salmonella.
Cholera--
Cholera, which is fully controlled in the United States,
has created a major global public health problem in India, Italy,
Portugal, and many other countries. In the United States, only
one case (in the Gulf Coast town of Port Lavaca, Texas) has
been reported since 1911. Transmission was associated with a
well that was contaminated by leachate from a septic tank system.
The etiological agent of cholera is Vibrio chplerae, Biotype
El Tor, Serotype Inaba or Ogawa. Man is the only known natural
host, and, since a prolonged carrier state is uncommon, the
disease must be maintained by an unbroken chain of mild, subtle
infections. Cholera is a serious disease, similar to typhoid
fever but more rapid in onset, more virulent, and more often
fatal. Death rates of 25 to 85 percent are commonly reported
(142).
The primary means of cholera transmission is the drinking
of contaminated water. Also associated with cholera is the
eating of fish caught in contaminated waters. In the event that
imported cases occurred in the United States, it is felt that
the risk of spread would be minimal because of modern, indus-
trialized sanitary engineering as well as responsible medical
therapy. It is also reported that vaccination is not needed
to control imported cases or outbreaks that may occur in the
United States (144).
The minimum doses of vibrio that cause clinical symptoms
in adult humans may vary (depending upon the strains of vibrio
that are used) from 103 cells (in up to 50 percent of the
individuals) to 105 cells (in up to 75 percent of the individuals),
as shown in Table 103.
270
-------
Gastroenteritis--
There are many reports of waterborne gastroenteritis of
unknown etiology in which bacterial infections are suspected.
These include outbreaks characterized by nausea, vomiting,
diarrhea, and fever, for which no specific etiologic agent
could be identified.
An epidemiological study of the impact of wastewater
pollution on marine bathing beaches was conducted during the
summers of 1973 and 1974 at the Coney Island and Rockaways
beaches in New York (95). A statistically significant finding
was observed: the rate of gastrointestinal symptoms among
swimmers compared to nonswimmers was higher at Coney Island,
where the densities of the indicative organisms such as E. coli
and fecal streptococci were significantly higher than the
densities at Rockaways Beach (Tables 108 and 109 ). It was
concluded that there were measurable health effects associated
with sewage polluted waters (95).
In 1971, a waterborne gastroenteritis outbreak was
reported in Pico Rivera, California, in which 11,000 residents
became ill with diarrhea and abdominal cramps. No pathogens
were isolated from any cases. The source of water was
responsible for the outbreak; chlorination at the reservoir had
been interrupted when the chlorine supply was exhausted. One
of the major outbreaks involving over 1,000 persons occurred
at Crater Lake National Park, Oregon, in July 1975. The
illness was reported to be associated with sewage-contaminated
water (459). Enterotoxigenic E. col i , Serotype 06:H16, was
isolated from ill park residents and from the park's water
supply (221) .
It was noted that the attack rate of acute "summer diarrhea"
on the Fort Apache Reservation, Arizona, during 1971, rose
simultaneously with rainfall, temperature, and bacterial
contamination of water sources (703). Nonenteropathogenic
E. coli capable of producing enterotoxin was isolated.
In the study of clinical response of adult humans to
challenge doses of E. coli, it has been demonstrated that very
large doses of cells (about 108) would be necessary to show
clinical response in 75 percent of the individuals tested
(Table 103 ). With the E. coli strain of 0111:84, doses of
only 106 cells were necessary for a similar response. However,
it should be noted that the digestive tract in most individuals
is populated by normal flora, of which E. coli is the most
abundant and most characteristic; about 10^/g of feces is
common(44) .
271
-------
N)
-vl
K)
TABLE 108. MEAN INDICATOR DENSITIES AT THE CONEY ISLAND
AND ROCKAWAYS BEACHES, NEW YORK, DURING 1973 AND 1974 TRIALS (95).
Indicator
Total coliforms
Fecal coliforms
Escherichia coli
Klebsiella
Enterobacter-cltrobacter
Fecal streptococci
Pseudomonas aeruginosj^
Aeromonas hydrophila
Vibrio parahaemol yticus
Log Mean Recovery/100 ml
1973
Coney Isl .
983*
165*
174*
112*
530*
91.2
30.4
25.3
ND
Rockaways
39.8
21 .5
24.8
13.7
11.1
21 .8
6.5
26.5
ND
1974
Coney Isl .
1213*
565*
15.3*
59.2*
434
16.4*
45.8*
9.6
54.5
Rockaways
43.2
28.4
2.4
3.5
6.6
3.5
3.1
4.9
32.8
*Significantly different at 95 percent confidence level.
-------
TABLE 109 . SYMPTOM RATES IN PERCENT AT CONEY ISLAND AND ROCKAWAYS BEACHES,
NEW YORK. DURING 1973 AND 1974 TRIALS(95)
Symptom
Group
Rates in Percent for Symptom
1973
Coney Island
S
NS
X
Rockaways
S NS
X
Groups in
1974
Coney Island
S
NS
X
Rockaways
S NS x
NJ
N
Resp.
G.I.
Other
"Severe"
474
12.9
7.2a
9.9
5.9
167
10.2
2.4
6.6
4.2
2.7
4.8
3.3
1.7
484
18.0ab
8.1
9.1
6.0
197
11.7
4.6
8.6
5.6
6.3
3.5
0.5
0.4
1961
7.2
4.2a
7.3
3.8
1185
6.4
2.6
6.7
2.9
0.8
1.6
0.6
0.9
2767
8.3
3.9
8.6
3.0
2156
7.8
3.5
7.7
2.6
0.5
0.4
0.9
0.4
a Significantly (P = 0.5) higher than nonswimmers.
b Significantly (P = 0.5) higher than other beach.
N-sample size; S-swimmers; NS-nonswimmers;x-difference
GI - gastrointestinal; Resp. - respiratory
-------
Leptosplrosis--
Etiological agents of 1eptospirosis (an infection caused
by leptospira) constitute approximately 150 different serotypes
categorized on the basis of their agglutinogenic properties
(383). The pathogenic serotypes are otherwise indistinguishable
by morphology or biochemical activity.
Recognition of two species, Leptospira interrogans and
L._ biflexa, has been proposed for the so-called pathogenic and
saprophytic leptospires, respectively (383).
Generally, 1eptospirosis, typically a disease of animals,
has been regarded as an occupational disease that occurs
primarily in workers associated with wastewater, rice, sugar
cane, farms, and slaughter yards. The disease is transmitted
to man by direct contact or via water contaminated by urine
from infected wild and domestic animals. Leptospirosis is
endemic in some parts of the world. However, 11 outbreaks in
nonendemic areas during 1939 to 1959 were associated with
swimming or wading in contaminated water (144, 283), indicating
the potential for contacting the disease as a result of
recreational activity.
At the same time, leptospirosis has become a more recognizable
human health problem in recent years, because of better identifi-
cation of symptoms and improved methods of diagnosis. In rural
populations in France, the percentage of infection by source was
as follows: water or mud, 21 percent; animals, 53 percent; and
water and animals, 25 percent. In nonrural populations, how-
ever, 80 percent of the infections was acquired by contact
with contaminated water (144). It was also noted that sub-
clinical leptospirosis in humans was not infrequent and may be
a significant public health hazard (144). Information on the
infective dose of leptospira to humans is not available from the
literature surveyed. Leptospira can apparently penetrate intact
skin, assisted by cuts, abrasions, and immersion. Incidences of
infection from swimming also suggested penetration via the
mucous membranes of the mouth or nasopharynx (144) . The nesting
site of leptospires in natural hosts is the lumen of nephritic
tubules, from which they are shed into the urine (144). Patho-
genic leptospires can survive for three or more months in neutral
or slightly alkaline waters, but do not persist in brackish or
acidic water (144). In 1975, two outbreaks of leptospirosis
were attributed to swimming in contaminated surface water. Seven
children in Tennessee developed infection with L. interrogans
serotype grippotyphosa after swimming in a small local stream.
Two persons in Louisiana became infected with leptospires of the
serotype icterohaemorrhagiae after bathing in a man-made lake (221)
274
-------
Tuberculosis--
The possibility that tuberculosis may be transmitted by
sewage has frequently been considered in connection with the
disposal of wastewaters from hospitals, tuberculosis sanitaria,
dairies, and slaughter houses; the possibility has even been
considered in connection with domestic sewage in general.
Concern has been expressed about the danger of human and animal
infection, particularly where these waters are reused (266).
The presence of mycobacteria in wastewater has been
extensively studied since around 1900 - the time of the first
findings of the bacteria in feces (223). The recovery of
Mycobacterium tuberculosis (the bacteria that cause tuberculosis)
is difficult, even from favorable sources such as sputum;
recovery from sewage is much more difficult because of the
presence of other bacteria.
The tubercle bacilli are present in the sputum and feces
of tuberculosis patients. The wastes from institutions that
treat the patients will almost always contain large numbers
(4 x 105 to 10//£ ) of tubercle bacilli (266). Significant
numbers (about 3/£ in the effluent of a plant producing about
7,600 gpd of milk) of virulent tubercle bacilli are also found
in the wastes from some dairies. A cow suffering with tuber-
culosis of the udders discharges about 1.5 x 10** tubercle
bacilli/day (266). M. balnei , which causes granuloma, may be
present in chlorinate~d~ water used for swimming pools (295)
of the data on survival of tubercle bacilli in sewage Indicate
that, under laboratory conditions, the bacteria can be infective
for 6 months in sewage and for up to 24 months in feces (266).
Contaminated water can produce typical tuberculosis in
humans in some instances. The first clear-cut cases of human
infection were reported in 1947. From 1947 to 1953, nine cases
of tuberculosis were described in humans who aspirated polluted
water into their lungs after swimming and nearly drowning in
contaminated water (266).
There were not much data available in the literature on
the infectious dose to humans of tubercle bacilli in wastewater.
In an experiment with guinea pigs, it was reported that 80 per-
cent of the animals contracted the disease when they were fed
with grass that had been sprayed with more than 4 x 106 tubercle
bacilli. Calves that had been similarly fed also succumbed (266)
The majority of studies carried out on mycobacteria has
focused on the presence of M. tuberculosis in sanitarium wastes.
These studies may not providT a realistic picture of the danger
of infection from contaminated water.
275
-------
The potential health hazards of M. tuberculosis being
transmitted through sanitarium wastewaters, to drinking supplies,
and back to man in general appears to be quite remote.
Viruses--
In the past, transmission of waterborne viral diseases was
rarely recognized, due largely to lack of sensitive virus-detection
methods and precise quantification. With improved techniques for
concentrating viruses from large water samples, increasing
occurrences of viruses in water and wastewaters have been reported.
Viral transmission through water may take place in various ways:
bathing in contaminated water, eating contaminated seafoods,
drinking from untreated or improperly treated water sources,
or contacting contaminated waters. Enteric viruses have been
investigated with greater emphasis than any other group of
viruses, mainly because any virus excreted in the feces and
capable of producing infection when ingested is theoretically
transmissible by water. The human enteric viruses and the
diseases associated with them are listed in Tables 110 and 111.
TABLE 110. THE HUMAN ENTERIC VIRUSES
AND THE DISEASES ASSOCIATED WITH THEM (142)
Virus Subgroup
No. of
Types
Disease
Polio virus
Coxsackie virus
Group A
Group B
ECHO virus
Infectious hepatitis
Reovirus
Adenovi rus
26
6
34
K?)
3
32
paralytic poliomyelitis,
aseptic meningitis
herpangina, aseptic meningitis,
paralysis pleurodynia,
aseptic meningitis, acute
Infantile myocarditis
aseptic meningitis, rash and
fever, diarrhea! disease,
respiratory illnesses
infectious hepatitis
fever, respiratory infections,
diarrhea
respiratory and eye infections
276
-------
TABLE 111 . THE HUMAN ENTERIC VIRUSES THAT CAN BE WATERBORNE
AND KNOWN DISEASES ASSOCIATED WITH THESE VIRUSES (637)
Group
No. of
Types or
Subgroup Subtypes
Disease Entities Associated
with These Viruses
Pathologic Changes In
Patients
Organs Where
Virus Multiplies
Enterovlrus Pol1ov1rus
ECHO virus 34
r\>
Muscular paralysis
Aseptic meningitis
Febrile episode
Aseptic meningitis
Muscular paralysis
Gulllain-Barre's Syndrome
Exanthem
Respiratory diseases
Diarrhea
Epidemic myalgia
Pericarditis & myocarditis
Hepatitis
Destruction of motor
neurons
Inflammation of
meninges from virus
Vlremia and viral
multiplication
Inflammation of
meninges from virus
Destruction of
motor neurons
Destruction of
motor neurons
Dilation and rupture
of blood vessels
Viral Invasion of
parenchymiatous of
respiratory trarcts
and secondary Inflam-
matory responses
Destruction of
intestinal bacteria
Not well known
Viral invasion of
cells with secondary
responses
Viral invasion of
cells with secondary
responses
Intestinal mucosa
spinal cord,
brain stem
Meninges
Intestinal mucosa
and lymph
Meninges
Intestinal mucosa
spinal cord,
brain stem
Spinal cord
Skin
Respiratory tracts
and lungs
Intestine
Perfcardial and
myocardial tissue
liver parenchyma
-------
TABLE 111. (continued)
Group
No. of
Types or
Subgroup Subtypes
Disease Entitles Associated
with These Viruses
Pathologic Changes in
Patients
Organs Where
Virus Multiplies
Enterovirus Coxsackie
(cont'd) virus
N>
^1
00
B
>24 Herpangina
Acute lymphatic pharyngitis
Aseptic meningitis
Muscular paralysis
Hand-fcot-mouth disease
Respiratory disease
Infantile diarrhea
Hepatitis
Pericarditis & myocarditis
6 Pleurodynia
Aseptic meningitis
Muscular paralysis
Viral invasion of
mucosa with secondary
inflammatory responses
Viral invasion of
mucosa with secondary
inflammatory responses
Inflammation of
meninges from virus
Destruction of motor
neurons
Viral invasion of
cells of skin of
hands and feet and
mucosa of mouth
Viral invasion of
parenchyma of
respiratory tracts
and secondary inflam-
matory responses
Viral invasion of
cells of mucosa
Viral invasion of
liver cells
Same as before
Viral invasion of
muscle cells
Same as before
Same as before
Mouth
Lymph nodes
and pharynx
Meninges
Intestinal mucosa
spinal cord,
brain stem
Skin of hands
and feet and
much of mouth
Respiratory
tracts and
lungs
Intestinal
mucosa
Parenchyma cells
of liver
Same as before
Intercostal
muscles
Same as before
Same as before
-------
TABLE 111. (continued)
Group
No. of
Types or Disease Entitles Associated
Subgroup Subtypes with These Viruses
Pathologic Changes in
Patients
Enterovirus Coxsackie
(cont'd) virus B
(cont'd)
ro
vj
to
Reovirus
Adenovirus
6
31
Hepatitis
>2
Meningoencephalitis
Pericarditis, endocarditis,
mycarditis
Respiratory diseases
Hepatitis or rash
Spontaneous abortion
Insulin-dependent diabetes
Congenital heart anomalies
Not well known
Respiratory diseases
Acute conjunctivitis
Acute appendicitis
Intussusception
Sub acute thyroiditis
Sarcoma in hamsters
Infectious hepatitis
Organs Where
Virus Multiplies
Viral invasional
invasion of cells
Same as before
Same as before
Same as before
Viral invasion of
vascular cells (?)
Viral invasion of
insulin producing
cells
Viral invasion of
muscle cells
Not well known
Same as before
Viral invasion of
cells and secondary
inflammatory responses
Viral invasion of
mucosa cells
Viral invasion of
lymph nodes (?)
Viral invasion of
parenchyma cells
Transformation of
cells
Invasion of paren-
chyma cells
Meninges and
brains
Same as before
Same as before
Same as before
Placenta
Langerhans cells
of pancreases
Developing heart
Same as before
Conjunctival
cells and blood
vessels
Append1a and
lymph nodes
Intestinal lymph
nodes (?)
Thyroid
Muscle cells
Liver
-------
TABLE 111. (continued)
Group
No. of
Types or
Subgroup Subtypes
Disease Entitles Associated
with These Viruses
Pathologic Changes in
Patients
Organs Where
Virus Multiplies
Hepatitis
(cont'd)
Serus hepatitis
Down's Syndrome
Invasion of paren-
chyma cells
Invasion of cells
Liver
Frontal lobe
of brain,
muscle, bones
K>
00
O
-------
Infectious Hepatitis--
Apart from theoretical considerations, there are very few
viruses for which epidemiological evidence suggests transmission
by water. Infectious hepatitis (hepatitis A) is the only disease
caused by an agent having the characteristics of a virus for
which evidence of waterborne transmission has been accepted by
all workers in the field(468). Therefore, it is regarded as the
viral disease of greatest importance in wastewater.
In 1973 alone, a total of 59,200 cases of viral hepatitis A,
B, and a type unspecified were reported (221). In 1974, a total
of 59,340 cases of viral hepatitis - hepatitis A, B, and type
unspecified - were reported to CDC. This represents a rate of
28.1 cases/100,000 population, approximately the same rate as for
1973. Since 1971, 1974 is the first year to have shown rate
increases for two quarters; the increase in cases began in the
fourth quarter of 1973. The seasonal variation noted in the
1950s and early 1960s was not seen in 1974. The 48,709 cases
of acute hepatitis A and hepatitis, type unspecified, constituted
82.1 percent of the total cases of viral hepatitis reported in
1974 (291). Waterborne outbreaks of hepatitis A continue to
occur in the United States. From 1971 to 1973, these documented
outbreaks were associated with contaminated drinking water from
either municipal, semipublic, or individual water systems (144,
448). Use of contaminated spring or groundwater without proper
treatment or disinfection, and back-siphonage of contaminated
water into the distribution system were reported to be the
causes of the outbreaks. The majority of documented hepatitis A
outbreaks in municipal water systems in the United States between
1946 and 1971 occurred as a result of distribution system
contamination, primarily through cross connections and back-
siphonage.
Two outbreaks of shellfish-associated hepatitis involving
285 cases were reported in 1973(221). Both outbreaks - one
in Georgia and the other in Texas - were associated with the
eating of raw oysters. Epidemiologic evidence suggested that
two particular bays contaminated by flooding were the source of
the contaminated oysters.
A recent hepatitis outbreak of 14 cases was reported to
be associated with swimming in a grossly contaminated lake in
North Carolina, and with ingesting water from that lake. This
is the first time that such a definite case has been made for
the potential of contracting this disease while swimming in
sewage-polluted water* The probable fecal-oral trans-
mission of infectious hepatitis made the waterborne route
possible. This mode of transmission was vividly illustrated
by several large epidemics that took place in 1955 to 1956,
especially in India where 28,745 cases occurred (468).
281
-------
As far as the magnitude of waterborne infectious hepatitis
is concerned, the water route still only accounts for up to
1 percent of reported cases at any time for which information
is available (468).
Despite the increased interest and concern in infectious
hepatitis, its infectious agent has not yet been isolated and
cultured. One recent report (212) using microscopic techniques
was able to show the presence of viruslike particles, immunolo-
gically distinct from hepatitis B, in infected stools.
Poliomyelitis--
The infectivity of feces from persons with poliomyelitis
and the characteristic fecal excretion of the diseased persons
have been documented for years. The polio virus has been sought
and detected in sewage. Accordingly, the water route of trans-
mission has been implicated in several outbreaks of poliomyelitis
(see Table 112). Many cases of epidemics of poliomyelitis were
attributed to waterborne transmission through contaminated or
untreated water, but the evidence is not sufficient. It appears
that water transmission of the polio virus may be a rare occurrence
in the United States, but common in parts of the world lacking
adequate sanitary facilities. Six of the outbreaks attributed
to drinking water occurred in Sweden during the 1930s and 1940s
(468) and led to the early recognition of the importance of the
fecal-oral route in poliomyelitis.
Viral Gastroenteritis--
When a recognized pathogen cannot be isolated in cases
of gastroenteritis and diarrhea, the term viral is often used
to describe the symptoms. It is quite possible that forms
of gastroenteritis and diarrhea transmissible from person to
person are due to viruses.
Gastroenteritis and diarrhea! disease are believed to
have accounted for approximately 60 percent of all epidemics
of waterborne diseases throughout history. The number of
these cases that was due to viral agents is not known; if,
however, only a small portion of the cases was due to viral
agents, this number would still be quite substantial.
A viruslike particle, similar in appearance but immuno-
logically distinct from the hepatitis A, has been reported to
be associated with an acute infectious nonbacterial gastro-
enteritis (341). Shellfish-associated gastroenteritis has also
been reported (177).
282
-------
ro
CO
TABLE 112. PUBLISHED REPORTS OF POLIOMYELITIS ATTRIBUTED TO
CONTAMINATED DRINKING WATER(463)
No.
1
2
3
4
5
6
7
8
Yr of
occurrence
1913(?)-39
1944
1944
1948
1948
1949
1952
1953
References
Spaak, 1941
Kling, 1947
Kling, 1947
Faahraeus et al . , 1950
Faahraeus et al . , 1950
Huss et al. , 1952
Bancroft et al . , 1957
Little, 1954
Country
Sweden
Sweden
Sweden
Sweden
Sweden
Sweden
U.S.A.
Canada
Place or
type of
population
Rural district
Town
Town
Stockholm
suburb
Town
Malmoe
"Huskerville"
Edmonton
No. cases
attributed
to supply
10b
63
53
9
63C
138
45
76l>
a Unadjusted rate among persons presumably consuming contaminated supply.
b Estimated from author's data.
c Includes cases attributed to other modes of transmission.
-------
TABLE 112 . (continued)
00
-U
No.
1
2
3
4
5
6
7
8
Attack
rate per
100a
--
0.5
0.2
--
0.2
0.1
6.7
<0.1b
Character
of Episode
Sporadic cases
Epidemic
Epidemic
Sporadic cases
Epidemic
Epidemic
Epidemic
Epidemic
Duration of
waterborne
phase
Yrs
5 mo
3 mo
3 mo
7 mo
6 mo
5 weeks
2 weeks
Type of supply
held responsible
Private well , pond
Municipal system
Filtered surface water
Municipal system
Untreated deep well water
Municipal system
Proximate contamination
Municipal system
Untreated deep well water
Municipal system
Filtered surface water
Municipal system
Proximate contamination
Municipal system
Chlorinated surface water
a Unadjusted rate among persons presumably consuming contaminated supply.
b Estimated from author's data.
c Includes cases attributed to other modes of transmission.
-------
Infective Dose of Viruses
Virologists feel that one plaque-forming unit (pfu) - one
viral particle that grows in the laboratory media - constitutes
an infectious viral dose. However, there is a difference
between infection and disease (637); the diseased person mani-
fests a variety of symptoms and readily recognizes that he is
sick; an infected person has the material in his system, but
does not necessarily show symptoms of the disease. It has been
estimated that of every 100 to 1,000 people who are infected,
only one will manifest the clinical symptoms of disease. How-
ever, it is not quite as simple as these statistics suggest, for
an infected individual can serve as a carrier or source within
the community and transmit this disease to other people (637).
Table 113 shows the minimal infective doses of attenuated
polio virus for human hosts by oral routes. The infected rate
with 20 or more pfu was 100 percent; with 2 pfu, 67 percent of
the individuals was infected.
TABLE 113. MINIMAL INFECTIVE DOSES OF ATTENUATED
POLIO VIRUSES FOR HUMAN HOSTS BY ORAL ROUTES(637).
Subject
Adults
Premature
Infants
Poll
(SM
Poli
(Fox
Virus
o virus Type I
Strain)
o virus Type III
Strain)
Dose
(Pfu)
200
20
2
0.2
10
2.5
1
Carrier*
Rate
4/4
4/4
2/3
0/2
2/3
3/9
3/10
Infected
Percent
100
100
67
0
67
33
30
* Number of persons developed into carrier for the
virus/number of persons who had taken the virus orally.
It has been mentioned that infection with small amounts of
virus in water would probably immunize individuals rather than
produce disease. This may be substantiated by the fact that
sewage workers continually exposed to small amounts of infected
material had the lowest rate of absenteeism among all the occu-
pation groups studied (52).
An adequate biological indicator for viruses in various
waters is not currently available; however, efforts are being
made to find better indicators. For example, ratios of coli-
phages to human enteric viruses and the coliform-virus ratio
285
-------
have been investigated ('235, 364) Also, a high degree of
coliforms and coliphage occurring in water samples (346)' as
well as a yeast and two acid-fast bacilli recovered from waste-
water, resist chlorination at a level sufficient to inactivate
viruses. This suggests that they may be useful indicators of
wastewater chlorination efficiency (201).
286
-------
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341 «u* oonrtumtict PRINTING of net: 19?s jto-8»o/32 1.3
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
3. RECIPIENT'S ACCESSION-NO.
_L
TITLE AND SUBTITLE
Contaminants Associated with Direct and Indirect
Reuse of Municipal Wastewater
5. REPORT DATE
March 1978 issuing date
6. PERFORMING ORGANIZATION CODE
AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
PERFORMING ORGANIZATION NAME AND ADDRESS
SCS Engineers, Inc.
4014 Long Beach Boulevard
Long Beach, California 90807
10. PROGRAM ELEMENT NO.
1CC614
11. CONTRACT/GRANT NO.
68-02-2257
2. SPONSORING AGENCY NAME AND ADDRESS
Health Effects Research Lab-Cincinnati, OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 4^268
13. TYPE OF REPORT AND PERIOD COVERED
Final.. 7/1/76 - 12/1/77
14. SPONSORING AGENCY CODE
EPA/600/10
5. SUPPLEMENTARY NOTES
6. ABSTRACT
This report is an attempt to compile the published quantitative data
available concerning'the health effects associated with direct and indirect reuse
of treated municipal wastewater for potable purposes. The assembled information
includes data on the effectiveness of conventional water and wastewater treatment
and disposal operations in reducing public health contaminant concentrations, as
well as data on the transport of these contaminants through the environment back
to man. The data have been organized in such a manner that the various pathways
of pollutants to man can be evaluated for relative public health significance
in order to establish necessary research priorities.
Wastewater treatment processes evaluated include conventional secondary
treatment and tertiary processes. Wastewater disposal techniques evaluated include
direct discharge to fresh surface waters and land application. Water treatment
processes evaluated include conventional treatment (chemical coagulation, with or
without filtration, and disinfection) and advanced water treatment (carbon
adsorption, ion exchange, and reverse osmosis).
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
Waste water
Waste treatment
Potable water
Public health
Water
18. DISTRIBUTION STATEMENT
Release to public
Drinking water
Waste water reuse
Water treatment
Water Supply
19. SECURITY CLASS (ThisReport)
Unclassified
20. SECURITY CLASS (Thispage)
Unclassified
COSATI Field/Group
68D
21. NO. OF PAGES
357
22. PRICE
EPA Form 2220-1 (9-73)
342
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