Density and Viscosity of Water_3 potx

Background Prerequisites

The background prerequisites for this textbook are general chemistry, mathematics
up to calculus, and fluid mechanics. In very few instances, an elementary knowledge
of calculus is used, but mostly the mathematical treatment makes intensive use of
algebra. In fluid mechanics, the only sophisticated topic used is the Reynolds trans-
port theorem. Although this topic is covered in an undergraduate course in fluid
mechanics, it was thought advantageous to review it here. The other background
prerequisite is general chemistry. Environmental engineering students and civil engi-
neering students, in particular, seem to be very weak in chemistry. This part will
therefore also provide a review of this topic. Depending upon the state of knowledge
of the students, however, this part may or may not be discussed. This state of
knowledge may be ascertained by the instructor in the very first few days of the
course, and he or she can tailor the discussions accordingly.
The contents of this “Background Prerequisites” section are not really physical–
chemical treatment but just background knowledge to comfortably understand the
method of approach used in the book. This book is analytical and therefore must
require extensive use of the pertinent chemistry, mathematics, and fluid mechanics.
This section contains two chapters: “Introduction” and “Background Chemistry and
Fluid Mechanics.”

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Introduction

This book is titled

Physical–Chemical Treatment of Water and Wastewater

. This
chapter begins by defining wastewater and physical–chemical treatment of water
and wastewater and treats briefly the coverage. It also addresses the unit operations
and unit processes. In addition, in the environmental engineering field, construction
of water and wastewater treatment plants and the requirements of their levels of
performance are mostly driven by government laws and regulations. For example,
the Clean Water Act mandates construction of wastewater treatment facilities that,
at least, must produce the secondary level of treatment. The Safe Water Drinking
Water Act also requires performance of treatment plants that produce drinking water
of quality free from harmful chemicals and pathogens. For these reasons, the Clean
Water Act and the Safe Drinking Water Act are discussed at length, detailing their
developments and historical perspectives.

WASTEWATER

Wastewater

is the spent water after homes, commercial establishments, industries,
public institutions, and similar entities have used their waters for various purposes.
It is synonymous with

sewage

, although sewage is a more general term that refers
to any polluted water (including wastewater), which may contain organic and inor-
ganic substances, industrial wastes, groundwater that happens to infiltrate and to
mix with the contaminated water, storm runoff, and other similar liquids. A certain
sewage may not be a spent water or a wastewater.
The keyword in the definition of wastewater is “used” or “spent.” That is, the
water has been used or spent and now it has become a

waste water

. On the other
hand, to become a sewage, it is enough that water becomes polluted whether or not
it had been used. When one uses the word wastewater, however, the meaning of the
two words is blended such that they now often mean the same thing.

Wastewater

equals

sewage

.

PHYSICAL–CHEMICAL TREATMENT OF WATER
AND WASTEWATER

What is physical–chemical treatment of water and wastewater? The dictionary
defines

physical

as having material existence and subject to the laws of nature.

Chemical

, on the other hand, is defined as used in, or produced by chemistry. Being
used in and produced by chemistry implies a material existence and is subject to

the laws of nature. Thus, from these definitions, chemical is physical. The fact that
chemical is physical has not, however, answered the question posed.

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To explore the question further, we go to the definition of chemistry.

Chemistry

is defined as the branch of science that deals with the composition, structure, and
properties of substances and the transformation that they undergo. Now, from this
definition can be gleaned the distinguishing feature of chemical—the transformation
that the substance undergoes. The transformation changes the original substance into
an entirely different substance after the transformation. Chemical transformation can
be distinguished from physical transformation. In physical transformation, although
also involving a change, the change is only in appearance but not in substance. For
example, FeO in the beginning is still FeO in the end; the size of the particles may
have changed, however, during the process. We now define physical treatment of
water and wastewater as a process applied to water and wastewater in which no
chemical changes occur. We also define chemical treatment of water and wastewater
as a process applied to water and wastewater in which chemical changes occur.
Gleaning from these definitions of physical and chemical treatments, in the overall
sense, physical–chemical treatment of water and wastewater is a process applied to
water and wastewater in which chemical changes may or may not occur.

UNIT OPERATIONS AND UNIT PROCESSES

Figure 1 shows the schematic of a conventional wastewater treatment plant using
primary treatment. Raw wastewater is introduced either to the screen or to the

comminutor. The grit channel removes the larger particles from the screened sewage,
and the primary clarifier removes the larger particles of organic matter as well as
inorganic matter that escapes removal by the grit channel. Primary treated sewage
is then introduced to a secondary treatment process train downstream (not shown)
where the colloidal and dissolved organic matter are degraded by microorganisms.
The scheme involves mere physical movement of materials, no chemical or
biological changes occur. In addition, the function of the various operations in the
scheme, such as screening, may be applied not only to the primary treatment of
sewage as the figure indicates but to other plant operations as well. For example,
bagasse may be screened from sugar cane juice in the expression of sugar in a sugar
mill, or the larger particles resulting from the cleaning of pineapples in a pineapple
factory may be screened from the rest of the wastewater. To master the function of
screening, it is not necessary that this be studied in a wastewater treatment plant, in

FIGURE 1

A primary treatment system.
Raw
sewage
Comminutor
Grit channel
Screen
Primary
clarifier
Effluent
Sludge

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Introduction

5

a sugar mill, or in a pineapple factory. It can be studied in any setting where screens
are used.
Furthermore, the functions of the operation of the primary clarifier may be
applied not only to the treatment of sewage as indicated in the schematic but also
to the clarification in a water treatment plant, as well as in the clarification of tailings
in a mining operation. Similar statements may be made about the operation of the
grit channel. In other words, to master the function of clarification and grit removal,
it is not necessary that these be studied in a sewage treatment plant or in a water
treatment plant. It can be studied in any setting where clarifiers and grit removal are
used.
The foregoing operations are physical; they are therefore physical treatments.
These physical treatments are called

unit operations

and as gleaned from the previous
discussion they may be defined as physical treatments that are identified only accord-
ing to their functions without particular reference to the location of the units utilizing
the functions. For example, screening may be studied without particular reference
to any sugar mills or pineapple factories. The unit operations of clarification may
be studied without particular reference to any wastewater or water treatment plants
or mining operations. The unit operations of grit removal may also be studied without
particular reference to any sewage plant but only to any setting where grit removal
is involved.
The unit operations discussed previously are all physical operations. In the
biological or chemical scene where materials are changed, unit operations have

counterparts called

unit processes

. Examples of unit processes are

coagulation

and

biological oxidation

. In coagulation, a chemical called coagulant undergoes a chem-
ical reaction. This chemical reaction may occur in any plant or factory or any location
at all where the function of the chemical reaction in coagulation is utilized. For
example, coagulation is employed in water treatment to enhance the settling of the
turbidity of raw waters. Coagulation may also be used in the clarification of sugar
cane juice to remove the fibers that the juice may contain.
The other unit process, biological oxidation, is used in sewage treatment; it may
also be used in biofiltration applied in water treatment. The biological reaction that
occurs in either sewage treatment or biofiltration are the same. In other words, the
function of the biological reaction is the same whether the reaction occurs in sewage
treatment or in biofiltration.
Coagulation and biological oxidation are identified on the basis of the function
of their characteristic chemical or biological reactions irrespective of the plant,
factory, or any other location that uses the reactions. The function of a coagulation
reaction is coagulation whether the reaction occurs in a water treatment plant or in
a sugar plant; and the function of a biological oxidation reaction is biological
oxidation whether the reaction occurs in a sewage treatment plant or in a water
treatment plant. The setting is immaterial; what is of concern is the function of the

chemical reaction. Unit processes may therefore be defined as chemical (or biolog-
ical) treatments that are identified only according to the functions of the chemical
(or biological) reactions irrespective of where the units utilizing the reactions are
occurring.

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6

Physical–Chemical Treatment of Water and Wastewater

COVERAGE

This book is divided into four general parts and addresses important topics on the
physical–chemical treatment of water and wastewater. The “first” part is titled
Background Prerequisites. Its contents are not really physical–chemical treatment
but just background knowledge to comfortably understand the method of approach
used in the book. This book is analytical and therefore requires the use of pertinent
chemistry, mathematics, and fluid mechanics. Relevant prerequisite topics are dis-
cussed in this part.
Part I, Characteristics of Water and Wastewater, covers the chapters on quantity
and constituent physical and chemical characteristics of water and wastewater. Part II,
Unit Operations of Water and Wastewater Treatment, includes the chapters on flow
measurements and flow and quality equalization; pumping; screening, sedimentation,
and flotation; mixing and flocculation; conventional filtration; advanced filtration and
carbon adsorption; and aeration and stripping. Part III, Unit Processes of Water and
Wastewater Treatment, includes the chapters on coagulation; water softening; chem-
ical stabilization; removal of iron and manganese; removal of phosphorus; removal
of nitrogen by nitrification–denitrification; ion exchange; and disinfection. Removal

of nitrogen by nitrification–denitrification, on the surface, is a biological process.
To control the process, however, its intrinsic chemical reactions must be unraveled
and totally understood. The treatment (as used in this textbook) therefore turns
toward being chemical in nature. The organisms only serve as mediators (i.e., the
producer of enzymes needed for the reaction). Thus, on the most fundamental level,
nitrogen removal by nitrification–denitrification is a chemical process (more, accu-
rately, a biochemical process), which is subsequently included as a chapter in Part
III of this book.

CLEAN WATER ACT

To gain a broader perspective of the Clean Water Act, it is important to know about
the United States Code (USC).* This code is a consolidation and codification of the

general

and

permanent laws

of the United States. It contains several titles; in one
of these titles, the Clean Water Act is codified. Because many of the general and
permanent laws required to be incorporated into the code are inconsistent, redundant,
and obsolete, the Office of the Law Revision Counsel of the House of Representatives
revises for enactment into law each title of the code. This process is called

positive
law codification

. Positive law codification is the process of preparing a bill and

enacting it into law, one title at a time, a revision and restatement of the general and
permanent laws of the United States. This codification does not change the meaning
or legal effect of the statute but removes ambiguities, contradictions, and other
imperfections from the law. Certain titles of the code have now been enacted into
positive law, and pursuant to Section 204 of Title 1 of the code, the text of these
titles is legal evidence of the law. The other titles of the code that have not been

* The United States Code itself is public domain. Portions of the code can be used and redistributed
without permission from the U.S. Government Printing Office.

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Introduction

7

enacted into positive law are

prima facie

evidence of the laws contained in these
titles. Table 1 shows the listing of all the titles of the USC.
Refer to Table 1. The codification of the Clean Water Act is within Title 33,
Navigation and Navigable Waters. This title contains 41 chapters, the first chapter
being Navigable Waters Generally and the 41st chapter being National Coastal
Monitoring. Chapter 26 of this title is Water Pollution Prevention and Control. This
is the codification of the Clean Water Act.
Each title of the USC is divided into several sections. Title 33, of course, starts with
Section 1, which is under Chapter 1, Navigable Waters Generally. Chapter 26 starts at

Section 1251 and ends at Section 1387. A portion of the USC is cited by specifying
the title number before the USC and the section or the range of sections after the USC.
For example, 33 USC 1251-1387 is the codification of the Clean Water Act.
Environmental pollution is global. Both developed and developing countries all
experience this problem. These countries therefore enact laws and regulations to

TABLE 1
The United States Code

Title 1 General Provisions Title 26 Internal Revenue Code
Title 2 The Congress Title 27 Intoxicating Liquors
Title 3 The President Title 28 Judiciary and Judicial Procedure
Title 4 Flag and Seal, Seat of
Government, and the States
Title 29 Labor
Title 30 Mineral Lands and Mining
Title 5 Government Organization and
Employees
Title 31 Money and Finance
Title 32 National Guard
Title 6 Surety Bonds (repealed) Title 33 Navigation and Navigable Waters
Title 7 Agriculture Title 34 Navy (repealed)
Title 8 Aliens and Nationality Title 35 Patents
Title 9 Arbitration Title 36 Patriotic Societies and Observances
Title 10 Armed Forces Title 37 Pay and Allowances of the Uniformed
ServicesTitle 11 Bankruptcy
Title 12 Banks and Banking Title 38 Veterans’ Benefits
Title 13 Census Title 39 Postal Service
Title 14 Coast Guard Title 40 Public Buildings, Property, and Works
Title 15 Commerce and Trade Title 41 Public Contracts

Title 16 Conservation Title 42 The Public Health and Welfare
Title 17 Copyrights Title 43 Public Lands
Title 18 Crimes and Criminal Procedure Title 44 Public Printing and Documents
Title 19 Customs Duties Title 45 Railroads
Title 20 Education Title 46 Shipping
Title 21 Food and Drugs Title 47 Telegraphs, Telephones, and
Radiotelegraphs Title 22 Foreign Relations and
Intercourse Title 48 Territories and Insular Possessions
Title 23 Highways Title 49 Transportation
Title 24 Hospitals and Asylums Title 50 War and National Defense
Title 25 Indians

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8

Physical–Chemical Treatment of Water and Wastewater

control the continuing pollution of the environment. In the United States, the passage
of the Rivers and Harbors Act of 1899 may be considered as the first law controlling
water pollution. Subsequently, the Federal Water Pollution Control Act, codified as
33 U.S.C. 1251-1387, was passed in 1948. The Federal Water Pollution Control Act
is the full name of the Clean Water Act mentioned in the previous paragraphs. This
Act is the principal law governing pollution of surface waters of this country. The
following years show various amendments to this act: 1956, 1961, 1965, 1966, and
1970; but it was in 1972 that the act was totally revised by amendments to have
taken practically its current shape. The 1972 legislation spelled out ambitious
programs for water quality improvement that have since been expanded by various
additional amendments. Congress made certain fine-tuning amendments in 1977,

revised portions of the law in 1981, and enacted further amendments in 1987, the
last year that the act was amended. Table 2 traces the dates of the major amendments
to the Clean Water Act and Table 3 summarizes the major sections of the Act
(indicated in the second column) as codified in the corresponding sections of the
USC (first column).
The following events were common before 1972: Lake Erie was dying; the
Chesapeake Bay was deteriorating rapidly; and the Potomac River was clogged with
blue-green algae blooms. Many of the rivers were like open sewers, and sewage
frequently washed up on shores. Fish kills were a common sight. Wetlands were
disappearing. The Cuyahoga River in Cleveland, Ohio, was burned because of gross
pollution due to a discharge of oil. To stop this widespread water pollution, in 1972,
Congress enacted the first comprehensive national clean water legislation—

the
Federal Water Pollution Control Act Amendments of 1972

.
The Clean Water Act focuses on improving the water quality of the nation. It
provides for establishment of standards, development of technical tools, and financial
assistance to address the causes of pollution and poor water quality, including
municipal and industrial wastewater discharges, nonpoint source runoff pollution

TABLE 2
Clean Water Act (Chapter 26) and Major Amendments

Year Act Public Law

1948 Federal Water Pollution Control Act P. L. 80-845 (June 30, 1948)
1956 Water Pollution Control Act of 1956 P. L. 84-660 (July 9, 1956)
1961 Federal Water Pollution Control Act Amendments P.L. 87-88

1965 Water Quality Act of 1965 P.L. 89-234
1966 Clean Water Restoration Act P.L. 89-753
1970 Water Quality Improvement Act of 1970 P.L. 91-224, Part I

1972 Federal Water Pollution Control Act Amendments P.L. 92-500

1977 Clean Water Act of 1977 P.L. 95-217
1981 Municipal Wastewater Treatment Construction Grants
Amendments
P.L. 97-117
1987 Water Quality Act of 1987 P.L. 100-4

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9

TABLE 3
Major U.S. Code Sections of the Clean Water Act

Code Section Subchapter
Subchapter I—Research and Related Programs

1251 Congressional declaration of goals and policy, Sec. 101
1252 Comprehensive programs for water pollution control, Sec. 102
1253 Interstate cooperation and uniform laws, Sec. 103
1254 Research, investigations, training and information, Sec. 104
1255 Grants for research and development, Sec. 105

1256 Grants for pollution control programs, Sec. 106
1257 Mine water pollution demonstrations, Sec. 107
1258 Pollution control in the Great Lakes, Sec. 108
1259 Training grants and contracts, Sec. 109
1260 Applications for training grants and contracts, allocations, Sec. 110
1261 Scholarships, Sec. 111
1262 Definitions and authorization, Sec. 112
1263 Alaska village demonstration project, Sec. 113
1265 In-place toxic pollutants, Sec. 115
1266 Hudson River reclamation demonstration project, Sec. 116
1267 Chesapeake Bay, Sec. 117
1268 Great Lakes, Sec. 118
1269 Long Island Sound, Sec. 119
1270 Lake Champlain management conference, Sec. 120

Subchapter II—Grants for Construction of Treatment Works

1281 Congressional declaration of purpose, Sec. 201
1282 Federal share, Sec. 202
1283 Plans, specifications, estimates, and payments, Sec. 203
1284 Limitations and conditions, Sec. 204
1285 Allotment of grant funds, Sec. 205
1286 Reimbursement and advanced construction, Sec. 206
1287 Authorization of appropriations, Sec. 207
1288 Areawide waste treatment management, Sec. 208
1289 Basin planning, Sec. 209
1290 Annual survey, Sec. 210
1291 Sewage collection system, Sec. 211
1292 Definitions, Sec. 212
1293 Loan guarantees, Sec. 213

1294 Wastewater recycling and reuse information and education, Sec. 214
1295 Requirements for American materials, Sec. 215
1296 Determination of priority, Sec. 216
1297 Guidelines for cost effective analysis, Sec. 217
1298 Cost effectiveness, Sec. 218
1299 State certification of projects, Sec. 219

(

continued

)

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Physical–Chemical Treatment of Water and Wastewater

TABLE 3 (

Continued

)
Major U.S. Code Sections of the Clean Water Act

Code Section Subchapter
Subchapter III—Standards and Enforcement

1311 Effluent Limitations, Sec. 301
1312 Water quality-related effluent limitations, Sec. 302
1313 Water quality standards and implementation plans, Sec. 303
1314 Information and guidelines, Sec. 304
1315 State reports on water quality, Sec. 305
1316 National standards of performance, Sec. 306
1317 Toxic and pretreatment effluent standards, Sec. 307
1318 Records and reports, inspections, Sec. 308
1319 Enforcement, Sec. 309
1320 International pollution abatement, Sec. 310
1321 Oil and hazardous substance liability, Sec. 311
1322 Marine sanitation devices, Sec. 312
1323 Federal facility pollution control, Sec. 313
1324 Clean lakes, Sec. 314
1325 National study commission, Sec. 315
1326 Thermal discharges, Sec. 316
1327 Omitted (alternative financing), Sec. 317
1328 Aquaculture, Sec. 318
1329 Nonpoint source management program, Sec. 319
1330 National estuary study, Sec. 320

Subchapter IV—Permits and Licenses

1341 Certification, Sec. 401
1342 National pollutant discharge elimination system, Sec. 402
1343 Ocean discharge criteria, Sec. 403
1344 Permits for dredge and fill materials, Sec. 404
1345 Disposal or use of sewage sludge, Sec. 405

Subchapter V—General Provisions

1361 Administration, Sec. 501
1362 Definitions, Sec. 502
1363 Water pollution control advisory board, Sec. 503
1364 Emergency powers, Sec. 504
1365 Citizen suits, Sec. 505
1366 Appearance, Sec. 506
1367 Employee protection, Sec. 507
1368 Federal procurement, Sec. 508
1369 Administrative procedure and judicial review, Sec. 509
1370 State authority, Sec. 510
1371 Authority under other laws and regulations, Sec. 511
1372 Labor standards, Sec. 513
1373 Public health agency coordination, Sec. 514
1374 Effluent standards and water quality information advisory committee, Sec. 515

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11

from urban and rural areas, and habitat destruction. For example, the Clean Water
Act requires:
• Establishment of water quality standards by the states and tribes for their
waters and development of pollution control programs to achieve them
• Establishment of a minimum level of wastewater treatment for all publicly
owned facilities
• Meeting of performance standards by major industries to ensure pollution

control
• Funding by the Federal government to states and communities to help
meet their wastewater infrastructure needs
• Protection of wetlands and other aquatic habitats through a permitting
process that ensures environmentally sound development
The 1972 Clean Water Act declared as its objective the restoration and mainte-
nance of the chemical, physical, and biological integrity of the nation’s waters. Two
goals were established: (1) zero discharge of pollutants by 1985; and (2) as an interim
goal, water quality that is fishable and swimmable by the middle of 1983. These goals
were, of course, not being met.
Aside from research and related programs provision, essentially, the Clean Water
Act consists of three major parts:
1. Regulatory requirements under the title of Subchapter III
2. Provisions that authorize federal financial assistance for municipal sewage
treatment plant construction under the titles of Subchapters II and VI
3. Permits and enforcement under the titles of Subchapters IV and III,
respectively.
In terms of historical perspective, these parts are discussed in sequence next.

TABLE 3 (

Continued

)
Major U.S. Code Sections of the Clean Water Act

Code Section Subchapter

1375 Reports to Congress, Sec. 516
1376 Authorization of appropriations, Sec. 517

1377 Indian tribes, Sec. 518

Subchapter VI—State Water Pollution Control Revolving Funds

1381 Grants to states for establishment of revolving funds, Sec. 601
1382 Capitalization grant agreements, Sec. 602
1383 Water pollution control revolving loan funds, Sec. 603
1384 Allotment of funds, Sec. 604
1385 Corrective actions, Sec. 605
1386 Audits, reports, fiscal controls, intended use plan, Sec. 606
1387 Authorization of appropriations, Sec. 607

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Physical–Chemical Treatment of Water and Wastewater

R

EGULATORY

R

EQUIREMENTS

As mentioned previously, the act requires each state and tribe to establish water
quality standards for all bodies of water in their jurisdictions (Section 303). The Clean
Water Act utilizes both water-quality- and technology-based effluent limitations to

meet these standards (Sections 301 and 302). Technology-based effluent limitations
are normally specified in discharge permits for industries, while water-quality-based
effluent limitations are normally specified in discharge permits for publicly owned
treatment works (POTWs), although the requirement of secondary treatment in
publicly owned treatment works is also technology-based. Water-quality-based effluent
limitations are derived by a water quality modeling which, for simple discharges,
uses the Streeter–Phelps equation.
Because of strict demands imposed on those who are regulated to achieve higher
and higher levels of pollution abatement, the act is a technology-forcing statute. For
example, the act started with only requiring the implementation of the secondary
and best practicable treatment (BPT) levels of treatment. The requirements, however,
gradually increased to requiring the use of the best available technology (BAT)
economically achievable, control of toxics, and control of nonpoint pollution sources.
The following scenario depicts the technology-forcing nature of the Clean Water
Act. Publicly owned treatment works were once required to meet the secondary
treatment level of treatment by July 1, 1977. By this date, industries were also
required the equivalent BPT level of treatment. Municipalities that were unable to
achieve the secondary treatment by the deadline were allowed to apply for extensions
on a case-by-case basis up to July 1, 1988. According to an estimate by the EPA,
86% of all cities met the 1988 deadline with the remainder being put under judicial
or administrative schedules requiring compliance as soon as possible.
By no later than March 31, 1989, the act required greater pollutant removal than
BPT, generally forcing that industry use BAT technology. Toxic pollutants are generally
the target of BAT levels of control. For industrial sources utilizing innovative or
alternative technology, compliance extensions of as long as two years were available.
Control of toxic pollutant discharges has now become a key focus in water
pollution abatement programs. For waters expected to remain polluted by toxic
chemicals even after industrial dischargers have installed the best available cleanup
technologies required under the law, the states are required to implement control
strategies, in addition to the BAT national standards. In the 1987 Clean Water Act

amendments, development of management programs for these post-BAT pollutant
problems was a prominent element. This would likely be a key continuing aspect
of any Clean Water Act amendments.
It should be realized that all these extensions for compliance are in the nature
of forcing the development of technology to achieve compliance. Thus, it is no
longer sufficient that the rule of thumb that has been traditionally used in environ-
mental engineering be used in an effort to meet requirements. Instead, the design
of unit operations and processes to achieve compliance should be instituted in a
more rational and analytical approach.
The original attention of the Clean Water Act prior to the 1987 amendments
was primarily directed at point source pollution, which includes wastes discharged

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13

from discrete and identifiable sources such as pipes and other outfalls, and did not
specifically address control of nonpoint pollution sources. Yet, nonpoint source
pollution is equally damaging to water quality. This type of pollution includes
stormwater runoff from agricultural lands, forests, construction sites, and urban
areas. It is this type of pollution that was the cause of a

Pfiesteria piscicida

outbreak
in August 1997 in the Chicamacomico River on the Eastern Shore of Maryland.
This is a microorganism that releases toxic substances and is widely believed to be

responsible for major fish kills and diseases in several mid-Atlantic states.
As the rain runs off, it picks up pollutant including sediments, toxic materials,
nutrients, and conventional wastes that can degrade water quality; these form the
nonpoint source pollution. Except for general planning activities, little attention had
been paid to these new types of pollution, despite estimates that nonpoint source
pollution represents more than 50% of the nation’s remaining water pollution problems.
In the 1987 amendments, Section 319 was added. This section authorizes mea-
sures to address nonpoint source pollution by directing states to develop and imple-
ment nonpoint pollution management programs. In these programs, states were
encouraged to pursue groundwater protection activities as part of their overall non-
point pollution control efforts. Federal grants were authorized to support demon-
stration projects and actual control activities.
Although the act imposes great technological demands, it also recognizes the
need for comprehensive research on water quality problems as stipulated in Title I.
Funds were provided for research in the Great Lakes (Section 118) and Chesapeake
Bay (Section 117), in-place toxic pollutants in harbors and navigable waterways
(Section 115), and water pollution resulting from mine drainage (Section 107). In
addition, the act also provides support to train personnel who operate and maintain
wastewater treatment facilities (Sections 109 and 110).

F

EDERAL

F

INANCIAL

A

SSISTANCE

The following treatment traces the history of federal financial assistance to the states.
The federal government has been giving grants for planning, design, and construc-
tion of municipal sewage treatment facilities since 1956. Beginning with the 1972
amendments, Congress has continued to expand this activity. Since that time, Con-
gress has appropriated $69 billion in funds to aid wastewater treatment plant plan-
ning, design, and construction. This appropriation has been made possible through
Titles II and VI of the Act. It is estimated that $140 billion more would be required
to build and upgrade needed municipal wastewater treatment plants in the United
States and for other types of water quality improvement projects that are eligible
for funding under the Act.
Under the Title II construction grants program established in 1972, federal grants
were made available for several types of projects such as secondary treatment,
advanced treatment, and associated sewers. Grants were given based on a priority
list established by the states (Section 216). The federal share of the total project cost
was generally as much as 55% (Section 202). For projects using innovative or
alternative technology such as reuse or recycling of water, as much as 75% federal
funds were available. Recipients were not required to repay the federal grants.

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Physical–Chemical Treatment of Water and Wastewater

Interested parties and policy makers have debated the tension between Title II
construction grants program funding needs and the overall federal spending and
budget deficits. The 1987 amendments to the Act dealt with this apparent conflict

by terminating federal aid for wastewater treatment construction in fiscal year 1994,
but providing a transition period toward full state and local government responsibility
for financing after this date. Grants under the traditional Title II were continued only
through fiscal year 1990.
To allow the states to be self-sustaining in financing their wastewater construc-
tion projects, Title VI was created to replace Title II as a federal funding mechanism.
This title authorizes grants to capitalize state water pollution control revolving
funds or loan programs (Section 603) beginning in fiscal year 1989. States contribute
20% matching funds, and under the revolving loan fund concept, monies used for
wastewater treatment construction will be repaid to a state fund, to be available for
future construction in other communities. All states now have functioning loan
programs, but the shift from grants to loans since fiscal year 1991, after the Title II
monies were discontinued in 1990, has not been easy for some. The new financing
requirements have been especially a problem for small towns that have difficulty
repaying project loans. Because of this problem, however, although statutory autho-
rization for grants to capitalize state loan programs expired in 1994, Congress has
continued to provide annual appropriations.

P

ERMITS



AND

E

NFORCEMENT

As mentioned earlier, the 1972 Clean Water Act declared as its objective the resto-
ration and maintenance of the chemical, physical, and biological integrity of the
nation’s waters. To achieve this objective, the Act assumes that all discharges into
the nation’s waters are unlawful, except as authorized by a permit. Several sections
of the Act require permits and licenses: Sections 402, 404, 405, 403, and 401.
Whereas some of these sections will be specifically addressed and explained in the
following, the others will not.
Because of discharge permit requirements, some 65,000 industrial and municipal
dischargers must obtain permits from the EPA or qualified states. This is required
under the National Pollutant Discharge Elimination System (NPDES) program of
Section 402 of the Act. An NPDES permit requires the discharger to attain technology-
based effluent limits (BPT or BAT for industry and secondary treatment for munic-
ipalities), or more stringent limits for water quality-limited waters. Permits specify
the control technology applicable to each pollutant, the effluent limitations a dis-
charger must meet, and the deadline for any compliance that must be met. For
POTWs with collection systems that receive discharges from industries, they are
required to incorporate a pretreatment program for their industrial contributors.
POTWs are required to maintain records and to carry out effluent monitoring activ-
ities. Permits are issued for 5-year periods and must be renewed thereafter to allow
continued discharge.
The NPDES permit incorporates numerical effluent limitations and best man-
agement practices. Whereas the BPT and secondary limitations focus on regulating
discharges of conventional pollutants, the more stringent BAT limitations emphasize

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15

controlling toxic pollutants such as heavy metals, pesticides, and other organic
chemicals. BAT limitations apply to categories of industries. In addition, the EPA
has issued water quality criteria for more than 115 pollutants, including 65 named
priority pollutants. These criteria recommend ambient, or overall, concentration
levels for the pollutants and provide guidance to states for establishing water quality
standards that will achieve the goals of the Act.
Disposal of dredge or fill materials into receiving bodies of water, including
wetlands, is controlled under a separate type of permit program. Authorized by Section
404 of the Act, the U.S. Army Corps of Engineers administers this program subject to
and using environmental guidance developed by EPA. Some types of activities such
as certain farming, ranching, and forestry practices that do not alter the use or character
of the land, are exempt from permit requirements. In addition, some construction and
maintenance activities that are deemed not to affect adversely the environment are
exempt from permit requirements. As has been done to Michigan and New Jersey, the
EPA may delegate certain Section 404 permitting responsibility to qualified states.
Due to the nature of wetlands, the wetlands permit program is a controversial
part of the law. Some of the wetlands are privately owned. If the owner wants to
develop the area, the law can intrude and impede private decision of what to do with
the property. On the other hand, environmentalists seek more protection for remain-
ing wetlands and want limits on activities that can take place there.
The other sections of the Act requiring permits and licenses include using and
disposing of sewage sludge (Section 405), ocean discharge (Section 403), and water
quality certification (Section 401). The Section 401 certification, obtainable from
the state, will show that the project does not violate state water quality standards.
The NPDES permit is the principal enforcement tool of the act. The EPA may
issue a compliance order or bring a civil suit in U.S. district courts against persons
violating the terms of a permit. The penalty for violation can be as much as $25,000
per day. Stiffer penalties are rendered for criminal violations such as negligent or
knowing violations. Penalties of as much as $50,000 per day or a three-year impris-

onment, or both may be rendered. For knowing-endangerment violations, such as
knowingly placing another person in imminent danger of death or serious bodily injury,
a fine of as much as $250,000 and 15 years in prison may be rendered. Finally, the
EPA is authorized to assess civil administrative penalties for certain well-documented
violations of the law. Section 309 of the Act contains these civil and criminal
enforcement provisions. Working with the Army Corps of Engineers, the EPA also
has responsibility for enforcing against entities who engage in activities that destroy
or alter wetlands.
Similar to other federal environmental laws, enforcement is shared by the EPA
and the states. Because of delegation agreements (to be addressed next), however,
the majority of actions taken to enforce the law are undertaken by states. This accords
the states the primary responsibility, with the EPA having oversight of state enforce-
ment. The EPA also retains the right to bring a direct action when it believes that a
state has failed to take timely and appropriate action or where a state or local agency
requests EPA involvement.
Finally, individuals may bring a citizen suit in U.S. district courts against persons
who violate a prescribed effluent standard or limitation (Section 505). Individuals may

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16

Physical–Chemical Treatment of Water and Wastewater

also bring citizen suits against the administrator of the EPA or equivalent state official
for failure to carry out a nondiscretionary duty under the Act.

F

EDERAL



AND

S

TATE

R

ELATIONSHIPS

Under the Clean Water Act, federal jurisdiction is broad, especially regarding the
establishment of national standards or effluent limitations. For example, the EPA
issues regulations containing the BPT and BAT effluent standards applicable to
categories of industrial sources such as iron and steel manufacturing, organic chem-
ical manufacturing, and petroleum refining. Certain responsibilities, however, are
delegated to the states, and this act stipulates a federal–state partnership in which
the federal government sets the agenda and standards for pollution abatement, while
states carry out day-to-day activities of implementation and enforcement (Section
510). Delegation agreements are signed between the governor of a state and the EPA.

SAFE DRINKING WATER ACT

Refer to Table 1. The codification of the Safe Drinking Water Act is found in Title
42, “The Public Health and Welfare.” The chapters of this title range from Chapter 1
to Chapter 139. Chapter 139, the last chapter, is “Volunteer Protection.” Chapter 1,
“The Public Health Service,” was repealed and renamed as Chapter 6A, but “The

Public Health Service” was retained as the chapter title. Subchapter XII of Chapter
6A is “Safety of Public Water Systems;” this is the Safe Drinking Water Act, which,
as passed by Congress, is called “Title XIV—Safety of Public Water Systems.” It
contains Sections 300f through 300j-26. The last section pertains to certification of
testing laboratories. Table 4 summarizes the major sections of the act (indicated in
the second column) as codified in the corresponding sections of the USC (first
column). The USC citation for the Safe Drinking Water Act is 42 USC 300f–300j-26.
In the United States, the passage of the Interstate Quarantine Act of 1893 can be
considered as the first law that eventually led to the establishment of drinking water
standards. Under this act, the surgeon general of the U.S. Public Health Service was
empowered to “

…

make and enforce such regulations as in his judgment are necessary
to prevent the introduction, transmission, or spread of communicable disease from
foreign countries into the states or possessions, or from one state or possession into
any other state or possession.” It was not until 1912, however, that the first water-
related regulation was promulgated. This regulation pertains to the simple prohibition
of the use of the common cup on carriers of interstate commerce such as trains.
The first act of Congress that had national importance was the Safe Drinking
Water Act (SDWA) of 1974. But before this enactment was made, several revisions
of the drinking water standards were made in 1914, 1925, 1942, 1946, and 1962.*
The following treatment traces the history of the gradually increasing trend of the
drinking water standards.
The year 1913 launched the first formal and comprehensive review of drinking
water concerns. It was quickly learned that the prohibition of the use of the common

* Pontius, F. W. at the American Water Works Association Web site.

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Introduction

17

TABLE 4
Major U.S. Code Sections of the SDWA (Title XIV—Safety of Public
Water Systems)

Code Section Part
Part A—Definitions

300f Definitions, Sec. 1401

Part B—Public Water Systems

300g Coverage, Sec. 1411
300g-1 National Drinking Water Regulations, Sec. 1412
300g-2 State Primary Enforcement Responsibility, Sec. 1413
300g-3 Enforcement of Drinking Water Regulations, Sec. 1414
300g-4 Variances, Sec. 1415
300g-5 Exemptions, Sec. 1416
300g-6 Prohibition on Use of Lead Pipes, Solder, and Flux, Sec. 1417
300g-7 Monitoring of Contaminants, Sec. 1418
300g-8 Operator Certification, Sec. 1419
300g-9 Capacity Development, Sec. 1420

Part C—Protection of Underground Sources of Drinking Water

300h Regulations for State Programs, Sec. 1421
300h-1 State Primary Enforcement Responsibility, Sec. 1422
300h-2 Enforcement of Program, Sec. 1423
300h-3 Interim Regulation of Underground Injections, Sec. 1424
300h-4 Optional Demonstration by States Relating to Oil or Natural Gas, Sec. 1425
300h-5 Regulation of State Programs, Sec. 1426
300h-6 Sole Source Aquifer Demonstration, Sec. 1427
300h-7 State Programs to Establish Wellhead Protection Areas, Sec. 1428
300h-8 State Ground Water Protection Grants, Sec. 1429

Part D—Emergency Powers

300i Emergency Powers, Sec. 1431
300i-1 Tampering with Public Water Systems, Sec. 1432

Part E—General Provisions

300j Assurances of Availability of Adequate Supplies of Chemicals Necessary for
Treatment, Sec. 1441
300j-1 Research, Technical Assistance, Information, Training of Personnel, Sec. 1442
300j-2 Grants for State Programs, Sec. 1443
300j-3 Special Project Grants and Guaranteed Loans, Sec. 1444
300j-3a Grants to Public Sector Agencies
300j-3b Contaminant Standards or Treatment Technique Guidelines
300j-3c National Assistance Program for Water Infrastructure and Watersheds
300j-4 Records and Inspections, Sec. 1445
300j-5 National Drinking Water Advisory Council, Sec. 1446
300j-6 Federal Agencies, Sec. 1447

(

continued

)

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18

Physical–Chemical Treatment of Water and Wastewater

cup was of no value if the water placed in it was not safe in the first place. In 1914,
the first drinking water standard was adopted. This required a limit for the total
bacterial plate count of 100 organisms/mL and stipulated that not more than one of
five 10-cc portions of each sample examined could contain

B. coli

(now called

Escherichia coli

). The standards were legally binding only on water supplies used
by interstate carriers.
By 1925, the technology of filtration and chlorination was already established,
and large cities encountered little difficulty in producing treated water in the range
of 2 coliforms per 100 mL. Conforming to the technology-forcing nature of regu-
lations, the standard was therefore changed to 1 coliform per 100 mL, establishing

the principle of attainability. The standard now also contained limits on lead, copper,
zinc, and excessive soluble mineral substances.
In 1942, significant new initiatives were stipulated into the standards. Samples
for bacteriological examination from various points in the distribution system were
to be obtained, requiring a minimum number of bacteriological samples for examina-
tion each month. The laboratories and the procedures used in making the examinations
became subject to state and federal inspection at any time. Maximum permissible
concentrations were also established for lead, fluoride, arsenic, and selenium. Salts of

TABLE 4 (

Continued

)
Major U.S. Code Sections of the SDWA (Title XIV—Safety of Public
Water Systems)

Code Section Part

300j-7 Judicial Review, Sec. 1448
300j-8 Citizen’s Civil Action, Sec. 1449
300j-9 General Provisions, Sec. 1450
300j-10 Appointment of Scientific, etc., Personnel by Administrator of Environmental
Protection Agency for Implementation of Responsibilities; Compensation
300j-11 Indian Tribes
300j-12 State Revolving Loan Funds, Sec. 1452
300j-13 Source Water Quality Assessment
300j-14 Source Water Petition Program

Part F—Additional Requirements to Regulate Drinking Water

300j-15 Water Conservation Plan
300j-16 Assistance to Colonials
300j-17 Estrogenic Substances Screening Program
300j-18 Drinking Water Studies
300j-21 Definitions
300j-22 Recall of Drinking Water Coolers with Lead-Lined Tanks
300j-23 Drinking Water Coolers Containing Lead
300j-24 Lead Contamination in School Drinking Water
300j-25 Federal Assistance for State Programs Regarding Lead Contamination in
School Drinking Water
300j-26 Certification of testing laboratories

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19

barium, hexavalent chromium, heavy metals, and other substances having deleterious
physiological effects were not allowed in the water system. Maximum concentrations
were also set for copper, iron, manganese, magnesium, zinc, chloride, sulfate, phe-
nolic compounds, total solids, and alkalinity.
In 1946, a maximum permissible concentration was added for hexavalent chro-
mium. The use of the salts of barium, hexavalent chromium, heavy metal glucosides,
and other substances were prohibited in water treatment processes. In addition, the
1946 standards authorized the use of the membrane filter procedure for bacteriolog-
ical examination of water samples.
In the early 1960s, over 19,000 municipal water systems had been identified.

These systems drew surface waters for treatment into drinking water. At this time,
however, federal water pollution control efforts revealed that chemical and industrial
wastes had polluted many surface waterways. Thus, the 1962 standards provided
the addition of more recommended maximum limiting concentrations for various
substances such alkyl benzene sulfonate, barium, cadmium, carbon-chloroform
extract, cyanide, nitrate, and silver.
All in all, the standards covered 28 constituents. The 1962 standards were the
most comprehensive pre-SDWA federal drinking water standards. Mandatory limits
were set for health-related chemical and biological impurities and recommended
limits for impurities affecting appearance, taste, and odor. The implementing regu-
lations, however, were legally binding only at the federal level, and were applicable
on only about 700 water systems that supplied common carriers in interstate com-
merce representing fewer than 2% of the nation’s water supply systems.* For the
vast majority of consumers, as an enforcement tool, the 1962 standards were of
limited use in ensuring safe drinking water.
The U.S. Public Health Service undertook a comprehensive survey of water
supplies in the United States, known as the Community Water Supply Study (CWSS).
Released in 1970, the study found that 41% of the systems surveyed did not meet
the 1962 standards. Many systems were deficient with respect to various aspects of
source protection, disinfection, clarification, and pressure in the distribution system.
The study also showed that, although the water served to the majority of the U.S.
population was safe, about 360,000 people were being supplied with potentially
dangerous drinking water.
The results of the CWSS generated congressional interest in federal safe drinking
water legislation. Subsequently, more studies revealed that dangerous substances
were contaminating drinking water. Thirty-six organic compounds were found in
the raw water supply of the Carrollton Water Treatment Plant in New Orleans,
Louisiana. This plant drew raw water from the Mississippi River, a river heavily
polluted with industrial wastes. Many of these wastes came from the manufacture
of synthetic organic chemicals (SOCs) and had found their way into the New Orleans

raw water supply. Three of the organic chemicals found in the raw water supply
were chloroform, benzene, and bis-chloroethyl ether. These chemicals are known
carcinogens. Additionally, trihalomethanes, a by-product of chlorination in drinking
water, were discovered in The Netherlands. Trihalomethanes are suspected carcinogens.

* Train, R. S. (1974). Facing the real cost of clean water,

J. AWWA

, 66, 10, 562.

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20

Physical–Chemical Treatment of Water and Wastewater

The occurrence of these chemicals in the drinking water supplies heightened
public awareness. As a result, Congress passed the Safe Drinking Water Act of 1974.
The drinking water regulations resulting from this Act were the first to apply to all
public water systems in the United States, covering both chemical and microbial
contaminants. Recall that, except for the coliform standard under the Interstate
Quarantine Act of 1893, drinking water standards were not legally binding until the
passage of the Safe Drinking Water Act of 1974. As shown in Table 5, the Act was
amended several times, the last being 1996.

H

IGHLIGHTS

OF



THE

S

AFE

D

RINKING

W

ATER

A

CT

The most important of the safe drinking water acts are the Safe Drinking Water Act
of 1974, the Safe Drinking Water Act Amendments of 1986, and the Safe Drinking
Water Act of 1996. The Safe Drinking Water Act was first enacted on December 16,
1974 to protect public drinking water systems in the United States from harmful
contaminants. The major provision of this Act requires the development of:

1. National primary drinking water regulations (Section 1412)
2. Underground injection control regulations to protect underground sources
of drinking water (Section 1428)
3. Protection programs for sole-source aquifers (Section 1427)
Most notably, the 1986 amendments include:
1. Setting drinking water regulations for 83 specified contaminants by 1989
2. Establishment of requirements for disinfection and filtration of public water
supplies and providing related technical assistance to small communities
3. Banning the use of lead pipes and lead solder in new drinking water
distribution systems
4. Establishing an elective wellhead protection program around public water
supply wells

TABLE 5
Safe Drinking Water Act and Major Amendments

Year Act Public Law

1974 Safe Drinking Water Act P.L. 93-523 (Dec. 16, 1974)
1977 SDWA Amendments of 1977 P.L. 95-190 (Nov. 16, 1977)
1979 SDWA Amendments of 1979 P.L. 96-63 (Sept. 6, 1979)
1980 SDWA Amendments of 1980 P.L. 96-502 (Dec. 5, 1980)
1986 SDWA Amendments of 1986 P.L. 99-339 (Jun. 16, 1986)
1988 Lead Contamination Control Act P.L. 100-572 (Oct. 31, 1988)
1996 SDWA Amendments of 1996 P.L. 104-182 (Aug. 6, 1996)

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21

5. Establishing an elective demonstration grant program for states and local
authorities having designated sole-source aquifers to develop ground
water protection programs
6. Issuing rules for monitoring wells that inject wastes below a drinking
water source
Finally, the most notable highlights of the 1996 amendments include:
1. Requiring community water systems serving more than 10,000 customers
to notify customers annually of the levels of federally regulated contam-
inants in the drinking water. These notifications must include information
on the presence of suspicious but still unregulated substances. If a viola-
tion of the standard occurs, the notifications must contain information
about the health effects of the contaminants in question.
2. Establishment of programs to train and certify competent water treatment
plant operators
3. Establishment of key drinking water standards for

Cryptosporidium

, cer-
tain carcinogens, and other contaminants that threaten drinking water in
the United States.

D

EVELOPMENT

OF

MCL

S



AND

MCLG

S

The Safe Drinking Water Act directs the EPA to develop national primary drinking
water standards. These standard are designed to protect human health. In addition,
secondary drinking water standards are developed to protect public welfare that deal
primarily with contaminants affecting drinking water aesthetics such as odor, taste,
and appearance. These standards are not federally enforceable and are issued only
as guidelines. The primary drinking water standards are enforceable on all public
water systems serving at least 25 persons.
With respect to setting standards, two terms have been invented: maximum
contaminant level goals (MCLGs) and maximum contaminant levels (MCLs).
MCLGs are health goals that are not enforceable. MCLs are the enforceable coun-
terpart of the MCLGs. They are set as close to the MCLGs as feasible and are based
upon treatment technologies, costs, and feasibility factors such as availability of
analytical methods and treatment technology. For lead and copper, MCLGs and
MCLs are not used; instead of specifying standards, water treatment is required.
The process of determining an MCL starts with an evaluation of the adverse

effects caused by the chemical in question and the doses needed to cause such effects.
The final result of this process is a safe dose that includes a margin of safety thought
to provide protection against adverse effects. This dose is called a reference dose
(Rf D) and is established based on the results of animal experiments. The research
results are extrapolated to humans using standard EPA methods. This extrapolation
varies depending upon whether the chemical is not a carcinogen, a known or probable
carcinogen, or a possible carcinogen.
For chemicals that do not cause cancer, an MCLG is established by first converting
the RfD to a water concentration. This number is then divided by five. The number

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22

Physical–Chemical Treatment of Water and Wastewater
five is based on the assumption that exposure to the chemical through drinking water
represents only one-fifth of all the possible exposures to this substance. Other sources
of exposure may include air, soil, and food. In most cases, the MCL established is
the same value as the MCLG.
For a known or probable carcinogen, (EPA Class A or B), the MCLG is set at
zero (i.e., no amount of chemical is acceptable). Because no analytical methods can
measure zero, however, the MCL is based on the lowest concentration that can be
measured on a routine basis. This is known as the practical quantitation limit (PQL).
Thus, it is obvious that for known or probable carcinogens, the MCL is not guar-
anteed to be a safe level but instead is the lowest measurable level.
For possible cancer-causing chemicals (EPA Class C—some evidence exists that
they may cause cancer, but it is not very convincing), a value equivalent to the
MCLG is calculated as if they were not carcinogens. This value is then divided by
a factor of ten to give the final MCL. Division by ten provides a margin of safety

in case the chemical is later determined to be a carcinogen.
DRINKING WATER REGULATIONS UNDER THE ACT
In support of each regulation, Section 1412(b) of the Act requires that the EPA must
make available to the public a document that specifies, to the extent practicable, the
population addressed by the regulation. The document must state the upper, central,
and lower estimates of risk and significant uncertainties and studies that would help
resolve uncertainties. Finally, the document must include peer-reviewed studies that
support or fail to support estimates.
Section 1412(b) further requires that whenever the EPA proposes a national
primary drinking water regulation, it must publish a cost-benefit analysis. In the
analysis for alternative MCLs, the effects on sensitive subpopulation must be con-
sidered; and in the analysis for treatment technique proposed for regulations, the
cost and benefit factors required for an MCL regulation must be taken into account,
as appropriate.
Section 1412(b)(6) requires that when the EPA proposes an MCL, it must publish
a determination as to whether the costs of the standard are justified by the benefits.
If the EPA determines that the costs of an MCL are not justified by the benefits, the
law allows the EPA to set an MCL that maximizes health risk reduction benefits at
a cost that is justified by the benefits. This section further limits the authority of the
EPA to adjust the MCL from the feasible level if the benefits are justified for systems
that serve 10,000 or more persons and for systems that are unlikely to receive a
variance. This section further provides that the determination by the EPA as to
whether or not the benefit of an MCL justifies the cost is judicially reviewable only
as part of a court’s review of the associated primary drinking water regulation.
Section 1412(b)(5) authorizes the EPA to consider “risk–risk” tradeoffs when
setting an MCL. In other words, an MCL may be set at a level other than the feasible
level if the technology to meet the MCL would increase health risk by (1) increasing
concentration of other contaminants in drinking water, or (2) interfering with treat-
ment used to comply with other primary drinking water regulations. When estab-
lishing such an MCL, the EPA shall (1) minimize overall risk by balancing both the

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Introduction 23
risk reductions from treating the individual contaminant and possible side effects of
such treatment on concentrations of other contaminants, and (2) assure that the
combination of treatments for the individual contaminant and other contaminants
shall not be more stringent than the “feasible.”
FEDERAL FINANCIAL ASSISTANCE
As discussed earlier under the Clean Water Act, the federal government has been
giving grants for planning, design, and construction of municipal sewage treatment
facilities in the form of revolving funds. Based on a similar concept, a State Revolv-
ing Fund (Section 1452) has been created to provide low interest loans to assist
community and nonprofit noncommunity water systems in installing and upgrading
treatment facilities. Part of this loan fund can be used to provide loan subsidies and
loan forgiveness to poor communities. Also, based on seriousness of health risk,
compliance needs, and system economic need, each year the states prepare plans
identifying eligible projects and their priorities.
FEDERAL AND STATE RELATIONSHIPS
As in the Clean Water Act, federal jurisdiction is broad, but the states have the
primary responsibility of enforcing the law (Section 1413) provided, however, that
the EPA has determined that the state to enforce the law has adopted drinking water
regulations that are no less stringent than the national primary drinking water reg-
ulations promulgated by the Administrator of the EPA. As a condition of primacy,
states have the authority to impose administrative penalties. For example, for systems
serving more than 10,000 persons, states are able to assess not less than $1,000 per
day per violation. For smaller systems, states only have the authority adequate to
ensure compliance. The EPA has the authority to take over the primacy, if the state
fails to implement the authority given to it in the delegation.
RELATIONSHIP OF THIS BOOK TO THE ACTS
As we learned from the previous discussions of the Clean Water Act and Safe

Drinking Water Act, more advanced and sophisticated technologies are needed for
the more stringent requirements in meeting the water quality standards and drinking
water standards. It is no longer sufficient that empirical knowledge be used in treating
water and wastewater. It is true that, armed with an empirical knowledge, an engineer
can proceed to design unit operations and unit processes that will treat a certain
contaminant. But to advance to the next level of sophistication in treatment, an
understanding of the underlying concept of the processes is important and, certainly,
would be necessary. For example, how do we economically remove trihalomethanes?
How about radionuclides and the 83 contaminants specified in the 1986 amendments
of the Safe Drinking Water Act? This book therefore presents the fundamental
concepts of the unit operations and unit processes used in the treatment of water
and wastewater. The authors hope to enlighten engineers and other professionals,
who are engaged in water and wastewater treatment practice, with the ability to
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24 Physical–Chemical Treatment of Water and Wastewater
answer not only the how but also the why of the physical and chemical treatment
of water and wastewater. It is, therefore, by necessity, analytical in nature.
GLOSSARY
Chemical treatment—A process applied to water and wastewater in which
chemical changes occur.
Physical treatment—A process applied to water and wastewater in which no
chemical changes occur.
Physical–chemical treatment—A process applied to water and wastewater in
which chemical changes may or may not occur.
Unit operations—Physical treatments that are identified only according to their
functions without particular reference to the location of the units utilizing
the functions.
Unit processes—Chemical (or biological) treatments that are identified only
according to the functions of the chemical (or biological) reactions, irre-

spective of where the units utilizing the reactions are occurring.
Wastewater—The spent water after homes, commercial establishments, indus-
tries, public institutions, and similar entities have used their waters for
various purposes.
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