ENCYCLOPEDIA OF ENVIRONMENTAL SCIENCE AND ENGINEERING - INDUSTRIAL WASTE MANAGEMENT pdf

In the following discussion, the reader will find a brief sum-mary of the major liquid wastes, their origin, characteristics and current methods of treatment for food, paper and allied p

INTRODUCTION

Industries produce large volumes of wastes that may include

a wide variety of chemicals containing most toxic pollutants

It has been estimated that there are over 300,000 water-using

factories in the United States. 1 As the population grows, the

need for manufactured goods will also increase As a result,

the volume of industrial wastes is expected to grow faster

than that of municipal wastes Some of the industrial wastes

can be treated jointly in municipal wastewater treatment

plants, but others must be pretreated at the source

In recent years, industrial wastewater management has

undergone vast changes Under legislative mandates and

technological advancement, industries are recognizing the

need and benefits of using water for several different

pur-poses in descending order of required cleanliness before

final treatment and release to the environment This

multi-ple, cascade, or sequential reuse of water minimizes the need

for new water supplies, and reduces and concentrates wastes

A benefit of water and residual reuse may be an economical

closed-loop, a zero discharge system that requires minimum

make-up water to function

Presented here is an overview of industrial

pollu-tion control legislapollu-tion and standards, Standard Industrial

Classification, industrial waste survey and monitoring, and

wastewater treatment systems for selected industries

INDUSTRIAL POLLUTION CONTROL

LEGISLATION AND STANDARDS

Water Pollution Control Legislation

Although water pollution legislative history in the United

States had its beginning with the Refuse Act of 1899, the

Federal Water Pollution Control Act Amendments of 1972 (PL

92-500) marked the greatest commitment to eliminating

pol-lutants in the nation’s lakes, rivers, and streams. 2 The following

is a summary of the last 40 years of water pollution control

legislation enacted by the Congress of the Unites States

• Federal Water Pollution Control Act of 1948

• Federal Water Pollution Control Act of 1956

• Federal Water Pollution Control Act Amendments

of 1961

• Water Quality Act of 1965

• Clean Water Restoration Act of 1966

• Water Quality Improvement Act of 1970

• Federal Water Pollution Control Act Amendments

of 1972

• Clean Water Act of 1977

• Clean Water Act Amendments of 1980

• Clean Water Act Amendments of 1981

• Water Quality Act of 1987 The 1972 and 1977 laws are collectively known as the Clean Water Acts. 3,4 They clearly express a serious national inter-est in water quality and reflect a strong public commitment

to end water pollution This legislation establishes deadlines for terminating pollution, enforcement provisions by federal, state, and local governments, and a greater federal degree of control over the quality of the nation’s waters The discharge

of pollutants into the nation’s waters is prohibited unless a

permit is obtained under the National Pollutant Discharge Elimination System ( NPDES ) There are about 50,000

indus-trial and 16,000 municipal NPDES permits at the present time. 5 These permits are issued by the states and must be renewed every 5 years The NPDES permit records effluent limits and spells out requirements for monitoring and record-ing Restrictions on amounts of specific pollutants that a given facility may discharge into surface waters are, in general, based on national effluent guidelines Industry has responded positively to the mandates of the law in meeting the discharge

limits based on the best available treatment technologies as

defined by EPA Under the NPDES permitting program efflu-ent limitations are established for toxic pollutants for various

industrial categories In a similar manner, industrial pretreat-ment standards are being developed for all pollutants that are discharged into the publicly owned treatment works (POTW)

Under the pretreatment regulations, two types of federal pre-treatment standards are established: (1) prohibited discharges and (2) categorical standards

Prohibited discharges to sewers or POTWs are those that cause a fire or explosion hazard, corrosion, obstruction, and slug discharges and heat discharges Categorical standards are developed for those pollutants that are incompatible, that

is, those that interfere with the operation of or pass through POTWs, or contaminate the sludge and other residues from POTWs

Substances considered for categorical standards are those for which there is substantial evidence of carcinogenicity,

mutagenicity, and/or teratogenicity; substances structurally

similar to aforementioned compounds; and substances known

to have toxic effects on human beings or aquatic organisms

at sufficiently high concentrations and which are present in

the industrial effluents There are many specific elements or

compounds that have been identified as priority pollutants

These include metals, organics, cyanides, and asbestos

To provide incentives, the Clean Water Act offered

federal cost sharing to cover 75 percent of treatment plant

construction In the 1987 amendments, Congress set up a

mechanism for states to develop revolving loan funds to pay

for future pollution control facilities. 6

Toxic Substance Control Act

The Toxic Substance Control Act of 1976 (TSCA), was

enacted to regulate the introduction and use of new

hazard-ous chemicals. 7 Under TSCA regulations, industry must

furnish data on the anticipated production, usage, and health

effects of all new chemical substances and mixtures before

they are manufactured for commercial distribution TSCA

also regulates the manufacture, processing, use, and final

disposal of all chemical substances

The Resources Conservation and Recovery Act of 1976

(RCRA) restricts the disposal of hazardous waste into the

atmosphere, bodies of water, or on land. 8 Thus RCRA was

enacted to protect the quality of groundwater, surface water,

the land, and the air from contamination by solid wastes

The Hazardous and Solid Waste Amendments of 1984

(HSWA) emphasized the protection of groundwater through

the use of leachate collection (double liners), and

monitor-ing of underground tanks; upgraded criteria for disposmonitor-ing

of municipal solid wastes in landfills; and established new

requirements for the management and treatment of small

quantities of hazardous wastes. 9

The Comprehensive Environmental Response

Compen-sation and Liabilities Act of 1980 (CERLA), the so-called

Superfund legislation, was designed primarily to address the

problem or the financial cleaning of abandoned or illegal

hazardous waste sites. 10 The Superfund Amendments and

Reauthorization Act of 1986 (SARA) provided funds and a

timetable and guidance for cleanup standards. 11

The Pollution Prevention Act of 1990 restates the waste

reduction mandate in the 1984 HSWA amendments to RCRA

A pollution prevention office within the EPA was also created

by this law along with the expansion of the reporting

require-ments of the SARA, emergency planning, and community

right-to-know provisions Organizations subject to these

pro-vision are required to report the steps taken to achieve waste

reduction. 12

STANDARD INDUSTRIAL CLASSIFICATION

The U.S Government Standard Industrial Classification

(SIC) lists 20 broad industry types bearing two-digit

identi-fication numbers More specific classiidenti-fication of industry is

achieved through three and four digit systems As an example,

Standard Industrial Classification 20 is for Food and Kindred Products; 202 for Dairy Products; and 2021, 2022 and 2023 for Creamery Butter, Cheese, and Condensed and Evaporated Milk. 13

MAJOR CONTAMINANTS—INDUSTRIAL SOURCES AND EFFECTS

The initial step in the rational development of industrial pol-lution control is to identify and characterize the major indus-trial contaminants Generally pollutants can be classified in three basic categories These categories and parameters are listed below:

(A) Physical Properties

Temperature Insoluble components Floating, settleable and suspended matters Color

Odor Foamability Corrosiveness Radioactivity

(B) Chemical Composition

Organic matter Inorganic matter Total dissolved solids Acid-Base

pH Acidity Alkalinity Nutrients Nitrogen Phosphorus Extractables Oil

Grease Reaction Oxidizing Reducing Chlorine demand

(C) Biological Effects

Decomposition Biodegradable Nonbiodegradable Toxic

Organic—phenols, pesticides, polychlorinated biphe-nyls (PCB), benzidine, etc

Inorganic—heavy metals and cyanide Pathogens

Industrial sources as well as major water quality effects

of some of these materials are summarized in Table 1. 14

INDUSTRIAL WASTE SURVEY

Industrial waste surveys are conducted to develop knowledge

of the waste streams from a specific industry A survey

pro-vides information on sewer lines, waste routing, and material

balance Since an industrial waste survey provides an

under-standing of the waste flow through the plant, and the potential

for water and residual reuse, a majority of the industries find

that the survey expenditures yield an excellent return. 15,16

Sewer Map

Of prime importance for any industry in operation at a site is

the development of an up-to-date sewer map showing water,

wastewater, and sanitary and storm drains Locating sewer

lines and establishing the manufacturing sources

responsi-ble for different waste streams becomes a time-consuming

and complex problem in older facilities Piping diagrams

are seldom updated as changes are made over the years

The sewer map should include details such as pipe size;

location and type of water supply and drain connections to

each processing unit; direction of flow; location of roof and

floor drains; manholes; catch basins and control points To

develop a realistic sewer map tracer, studies may be needed

Commonly used tracers are dyes, floats (wood chips, cork

floats, and stoppered bottles), and smoke

Flow Sheet

A flow sheet is prepared for each operation in the entire plant

It should show all raw materials, additives and products,

by-products, and liquid and solid wastes All primary

dis-charges from each process, and the type, period, and duration

of each operation should also be indicated on the flow sheet

Mass Balance

After developing the flow sheet the next step is to obtain the amounts of raw materials, additives, products, and wastes for each operation From the material balance, the extent of solid and liquid waste characteristics may be determined This mass balance acts as a check on the waste quantities determined in the preliminary sampling and analysis It also provides pre-liminary estimates of flows and parameters to be measured

Location of Sampling Stations

Sufficient sampling stations should be established to deter-mine the waste load at all of the major processes which con-tribute wastes A desirable feature of the sampling station

is that the flow be known If flow is not known, it may be established by use of a flow measurement device The sam-pling stations should be easily accessible with adequate safe-guards, and wastewater should be well mixed

Coordination with Production Staff

It is necessary that the efforts of the production staff be fully coordinated during the industrial waste survey The input and information supplied by the production staff is valuable in identifying the frequency of batch dumps, spills, overflows, and continuous discharges

SAMPLING AND MONITORING The basis for industrial pollution abatement programs rests upon information obtained by sampling and monitoring

of various waste streams Serious problems or inaccurate

TABLE 1 Major contaminants—industrial source and effect Type of contaminant Industrial source (some examples) Some major effects

Inorganic salts Oil refinery, desalination plants, munitions

manufacturing and pickle curing

Interferes with industrial usage municipal (drinking water), and agriculture (irrigation water) Acids and/or alkalies Chemical manufacturing, tanneries Corrosion of pipelines and equipment, kills fish

Organic matter Tanneries, canneries, textile mills etc Food for bacteria and thus depletes oxygen

Suspended matter Paper mills, canneries, etc Suffocates fish eggs, degrades stream appearance Floating solids and liquids Slaughterhouse, oil refinery Unsightly, odorous, interferes with oxygen transfer Heated water Cooling waters from most industries and power plants Accelerates bacterial action, lowers total oxygen

saturation level Color Textile, tanneries, metal finishing, and chemical plants Objectionable appearance

Toxic chemicals Munitions manufacturing, metal plating, steel mills,

petrochemicals, etc.

Alters stream biota and animal diversity

Microorganism Pharmaceutical, combined municipal—industrial plants Unsafe for drinking and swimming

Radioactivity Nuclear power plants, chemical laboratories Concentrates in fish, harmful for drinking

Foam-producing matter Glue manufacturing, slaughterhouse, detergent

manufacturing

Aesthetically objectionable

Source: Adapted from Ref (14)

information may result if sampling procedures and test

parameters are selected in a careless or naive manner

Flow Measurement

An essential part of the wastewater sampling and

monitor-ing program is the collection of flow data A knowledge of

flow rate, flow variability, and total flow is essential A

vari-ety of flow measuring devices are available the selection of

the proper measuring method or device will depend on

fac-tors such as cost, accessibility, type of flow, and character of

waste A list of many different types of methods and devices

commonly used for wastewater flow measurement are given

in Table 2. 2

Sampling

It is essential that waste stream samples be truly

representa-tive of the waste discharge Waste conditions may vary both in

magnitude and composition over a 24-hour period Therefore,

care should be taken in selecting the method of sampling,

fre-quency and duration, sample handling, and parameters to be

measured All these items are briefly discussed below

Method of Sampling

Two most common methods of sampling are known as grab samples and composite samples Either may be obtained

manually or automatically Grab samples are single batch samples taken at a given time Composite or integrated samples are taken at constant time intervals usually over

a 24-hour period, then mixed in proportion to flow at the time of sampling to obtain one representative sample of the total flow for the day

Grab samples provide valuable information at low cost They are recommended where: (1) condition or quality remains relatively uniform over long periods; (2) the effect

of slug loads are desired; (3) concentration of certain constit-uents are needed for adjustment of chemical feed; (4) flow is intermittent; and (5) the sample requires immediate analysis due to instability of the constituents

Composite sampling is done to obtain the average qual-ity data for the day Continuous samplers that take a sample volume in proportion to the flow are desirable Another type of composite sampler removes samples on the hour and deposits

it into different bottles A volume of sample from each bottle is mixed manually in proportion to flow to obtain the composite

TABLE 2 Types of flow measurement devices commonly used for measuring wastewater discharges Flow Measurement Devices Principle of Flow Measurement

1 For pressure pipes

a Venturi meter Differential pressure is measured

b Flow nozzle meter Differential pressure is measured

c Orifice meter Differential pressure is measured

d Electromagnetic meter Magnetic field is induced and voltage is measured

e Turbine meter Uses a velocity driven rotational element (turbine,

vane, wheel)

f Acoustic meter Sound waves are used to measure the velocity

2 For open channels

a Flumes (Parshall, Palmer-Bowlus) Critical depth is measured at the flume

b Weirs Head is measured over a barrier (weir)

c Depth measurement Float is used to obtain the depth of flow in the

sewer, and velocity is calculated from slope

d Acoustic meter Uses sound waves to measure velocity and depth

3 Computing flow from freely discharging pipes

1 Pipes flowing full

a Nozzles and orifices Water jet data is recorded

b Vertical open-end flow Vertical height of water jet is recorded

2 Pipe partly flowing full

a Horizontal open-end pipe Dimensions of free falling water jet are obtained

b Open flow nozzle (Kennison nozzle or

California pipe method)

Depth of flow at free falling end is determined

4 Miscellaneous methods

a Dilution method A Constant flow of a dye tracer is used

b Bucket and stopwatch A calibrated bucket is used and time to fill is

recorded

c Pumping rate Constant pumping rate and pumping duration are

recorded

average sample for the day Individual hourly samples are the

grab samples representing the condition at that instant

Frequency and Duration of Sampling

The frequency of sampling depends on the flow rate,

waste-water characteristics, and variability in quality and volume

The expected range in flow rate and waste concentration

should be determined by a preliminary survey Although

most of the time the frequency is one sample per hour, the

frequency for highly variable waste streams could be as high

as one sample every three minutes

An intensive plant survey will generally last between

five to ten days of normal plant operation Since the

treat-ment facilities must be designed to treat the highest pollution

load expected, it is important to consider seasonal variations

(if applicable)

Sample Handling

In order to obtain a representative sample it is necessary for

the sampling point to have sufficient hydraulic turbulence

Sufficient volume of the sample must be obtained to perform

all analyses planned The minimum volume of grab sample

should be between one to two liters Sample containers and

sampling device should be clean and uncontaminated Before

the sample is taken, the container should be rinsed several

times with the wastewater Each sample should be labeled

with an identification card containing the following

infor-mation: date and time, sample location, method of sampling

(grab or composite), and notation of information obtained

from field analyses of parameters that may change before

laboratory analyses are made (temperature, pH, appearance)

The sample should be analyzed as quickly as possible

Storage should be in a manner that insures that the

charac-teristics to be analyzed are not altered Refrigeration in most

instances is necessary In some cases a special chemical may

have to be added to prevent changes in chemical or biological

characteristics

Parameters Measured

A major item in any industrial monitoring program is the cost

of analytical measurement It is important that the parameters

be properly selected to represent inplant waste streams; and

waste characterization, treatment and reuse requirements In

some cases the necessary analyses will be time-consuming

and relatively expensive In many cases, an alternative

ana-lytical technique may be used that are less expensive Major

constituents of interest in industrial pollution monitoring are

listed in Table 1

Analytical Considerations

Good analytical procedures are of the utmost importance in

a monitoring program The basic references for wastewater

analytical procedures and techniques are EPA publications,

Standard Methods for Examination of Water and Wastewater,

and ASTM Standards. 17 – 20 The analysis may fall into several

major categories including routine wet chemistry, selective ion electrodes, automated wet chemistry, and bioassary tests

Data Analysis

Data obtained through a well-planned and executed moni-toring program will provide valuable information for waste process selection, plant design and operation, and assist the industry in evaluating the manufacturing process The mon-itoring program may result from changes in chemical use and/or industrial process, inplant spills or dumping of baths Variability of the parameters may be random or cyclic The data should be analyzed to establish the fluctuations with time, location, work shifts, and type of operation

Statistical techniques should be used to develop rela-tionships such as average or mean, standard deviation and extreme conditions, and regression coefficients With a knowledge of basic probability theory and the use of statis-tical techniques, such as least squares, curve fitting, analysis

of variance, regression and correlation analysis, chi-squared goodness of fit, and others, it is possible to construct math-ematical models and curves for almost any level of preci-sion desired Such techniques help to evaluate information having wide variations, so that an estimate of the best value

of the parameter being measured can be developed For more information the reader should consult several excellent references on statistical methods. 21 – 24

TREATMENT PROCESSES Industrial wastewater treatment utilizes a number of unit operations and processes to achieve the desired degree of treatment The collective treatment schematic is called a flow scheme, flow diagram, flow sheet, process train, or flow sche-matic Basic considerations for developing a flow scheme include: (1) the manufacturing process and its flow scheme; (2) characteristics of wastewater streams and degree of treat-ment; (3) requirements of the regulatory agency; (4) construc-tion cost; (5) level of expertise of treatment plant operaconstruc-tion personnel; and (6) operation and maintenance costs. 2

The wastewater treatment facilities are designed to process liquids and solids or sludges It is essential that in-plant waste management and control techniques be utilized if cost-effec-tive methods of liquid and solids treatment are to be attained Some application of in-plant controls include waste reduc-tion, waste segregareduc-tion, water conservation and recycle, and process modifications Generally, controlling wastes within the plant is much more cost-effective than implementation

of treatment Certain innovative processes that reduce waste production have resulted in improved process yield or by-product recovery and utilization

Waste Reduction

A basic materials balance procedure should be developed that accounts for all materials that enter and leave an individual department or processing area Some specific waste reduction

measures include: (1) materials balance accounting; (2)

improved process control; (3) more effective cleanup

proce-dures; (4) regular preventive maintenance; and (5) by-product

recovery Poor maintenance and cleanup procedures in many

industrial plants are a major source of wasteload generation

Product spills should be avoided, and when they occur,

the waste should be handled in a manner that will minimize

the contribution of wasteload to the plant Proper

housekeep-ing procedures should be developed and implemented

Waste Segregation

It is important to segregate all wastes in accordance with

the physical and chemical properties of the contaminants,

potential to react, and their treatability Important properties

are suspended solids, acidity, basicity, organic matter and

biodegradability, volatility, and toxic organics and

inorgan-ics Efforts should be made to minimize dilution of waste

streams prior to treatment and/or recovery of residuals

Diluted streams should be handled separately

Water Conservation and Recycle

Water conservation and recycle consist of minimizing the

raw water supply and maximizing the amount or wastewater

reuse within the plant The net effect of water conservation

and recycle is the reduction of wastewater volume and to

concentration of wasteloads

Each process should be investigated to minimize water

supply requirements and the potential for substituting

recy-cled or reclaimed wastewater for fresh water Water

qual-ity requirements for most industrial processes will govern

the feasibility or extent of water reuse However, in every

industry using water for washing, rinsing, or cooling, some

form of countercurrent flow or recycling can probably be

implemented for maximum reuse Some specific

recom-mendations for water conservation and recycle include:

(1) dry (nonwater) cleaning method, (2) water meters at

each department to make operators conscious of usage,

(3) automatic valves that close when water is no longer

required, (4) regular preventive maintenance programs that

include leak surveys, and (5) cleanup with high-pressure,

low-volume rinse sprays. 16

Process Modification

In-plant process modifications, though more costly to

imple-ment than simple operational changes, may be very effective

in controlling wasteload generation Process modifications

may consist of individual unit process changes, or changes to

a complete process line The cost-effectiveness of such

modi-fications will depend on the relative reduction in wasteloads

In older industrial plants, required process modifications may

be accomplished during the installation of newer and more

efficient equipment In the design of new plants, each

pro-cess should be evaluated with respect to use of more efficient

equipment for maximum water conservation and minimum

wasteload generation

Liquid Treatment Systems

The removal of various contaminants from the liquid depends

on the nature of the impurities and their concentrations Coarse and settleable inorganic and organic solids are gener-ally removed in sedimentation facilities Oil and grease is removed by skimmers The removal of dissolved organics is readily achieved in biological or chemical or physicochemi-cal treatment processes For example, chemiphysicochemi-cal oxidation-reduction reactions and precipitation are used for removal

of heavy metals Carbon adsorption can be used to remove refractory organics Ion exchange and membrane processes are suitable for demineralization and byproduct recovery Major physical, chemical, and biological treatment pro-cesses used for liquid treatment are summarized in Table 3 For extensive presentations on these processes the readers should refer to several excellent publications that provide detailed discussions on the theory and design of wastewater treatment processes. 2, 25 – 31

Sludge and Brine Processing and Disposal

Safe handling and disposal of residues and brines pro-duced in various treatment units are of equal importance Solids portions include screenings, grit, scum, organic and inorganic sludges Brines (high mineral concentrates) are produced from ion exchange, reverse osmosis, and electro-dialysis units In general, the sludge processing and disposal methods include thickening, stabilization, and dewatering or evaporation of liquid Several of the unit operations and pro-cesses used for sludge and brine handling and disposal are illustrated in Figure 1

MAJOR INDUSTRIAL WASTES AND TREATMENT

It should be recognized that to truly understand the waste problem of any industry, a lifetime serious effort on the part

of a qualified waste engineer may be required Production methods of each industry are normally different As a result, the treatment process train needed for the waste streams should be individually designed The purpose of this section

is to review the origin and characteristics of wastewater and methods of wastewater treatment for six major industries In the following discussion, the reader will find a brief sum-mary of the major liquid wastes, their origin, characteristics and current methods of treatment for food, paper and allied products, chemical, petroleum, metals, and power generation industries For a detailed study on these topics the readers should refer to several references on the subject included in the list of references. 32 – 35

Food Industry

There are approximately 50,000 food processing plants in the total food processing industry in the United States Food processing is a low-profit margin, highly com-petitive industry Water is required for washing, blanching,

TABLE 3 Major physical, chemical, and biological treatment unit operations and processes used for liquid treatment

Unit Operations and Processes Principal Applications

Screening Racks or bar screens are the first step in wastewater treatment They are used to remove large objects.

Flow equilization Used to dampen the flow rate and mass loading.

Skimming Used for oil separation where free oil is floated to the surface of a tank and then skimmed off The oil separator

specified by American Petroleum Institute is commonly used.

Dissolved Air Flotation (DAF) Process used to remove suspended solids, and oil and grease from the waste stream Uses dissolved air to

produce line bubble that float the solids.

Foam separation Process used to remove minute concentrations or refractory organics and heavy metal ions Contaminants are

carried up by rising bubbles to the pool surface where they are deposited as the bubbles exit.

Sedimentation Use to remove settleable solids.

Neutralization Process used to neutralize acidic or alkaline waste streams prior to chemical and/or biological treatment Precipitation Dissolved solids in solution are chemically transformed into insoluble form Process is extensively used to

precipitate phosphorous and heavy metals Heavy metals are generally precipitated as hydroxide through the addition of time or caustic to a pH of minimum solubility.

Chemical Oxidation Used to oxidize pollutants to terminal end products Common oxidants are Cl2, O3, H2O2, and KMnO4 Oxidation

of iron and manganese is used for precipitation Cyanides, sulfides and many organics arc destroyed by oxidation.

Chemical Reduction Used to precipitate certain ions from solutions, e.g., hexavalent chromium Also many oxidizing agents are

destroyed by reduction Common reducing agents are ferrous sulfate, sodium metabisulfite, and sulfur dioxide.

Coagulation Used to agglomerate suspended materials so that efficient settling can take place Commonly used chemicals are

alum, iron salts, and polymers The process consists of chemical feed, flash mix and flocculation basins Suspended growth biological reactor Biological process using suspended biomass to remove dissolved organics Principal variation is an activated

sludge process.

Attached growth biological reactor Biological process using attached biomass to remove dissolved organics Principal variations are a trickling

filter and a rotating biological contactor (RBC).

Anaerobic Processes Attached or suspended microbial process operated in the absence of oxygen Normally used to treat high strength

organic wastes Methane is produced as an energy source Sludge (biomass) production is small.

Oxidation Pond Large basins (normally earthern) used for waste storage and treatment Treatment is achieved by natural

processes of settling and biological decomposition.

Aerated Lagoon Basins (normally earthern and frequently with plastic liners) with aeration equipment where waste are aerated

over long periods of time The waste characteristics are altered by biological oxidation.

Land Treatment Organic waste is applied over land for treatment Common application methods are slowrate irrigation, rapid

infiltration, and overland flow.

Nitrification Process is used to convert ammonia nitrogen to nitrate nitrogen It can be achieved in suspended or attached

growth biological reactors.

Denitrification Nitrite nitrogen and nitrate nitrogen are reduced to nitrogen gas by microorganisms Denitrification is achieved

under anaerobic condition in suspended or attached growth reactors An organic source such as methanol is needed.

Disinfection Process used to reduce the number of water borne pathogens in water Normally applied to effluents of

wastewater treatment plants containing microbes Chlorination and ozonation are the most common methods.

Ammonia stripping Ammonia gas is air stripped from the wastewater, normally by using stripping tower High pH values are required Breakpoint Chlorination Ammonia nitrogen is oxidized to nitrogen gas by breakpoint chlorination in a mixing basin.

Filtration Used to polish the effluent by removing total suspended solids and turbidity Biological activity in the filter bed

may reduce some of the biochemical oxygen demand (BOD).

Carbon adsorption Used to remove soluble refractory organics from wastewater effluent.

Ion Exchange A demineralization process in which the cations and anions in wastewater are selectively exchanged for the ions

in an insoluble resin bed When the resin capacity is used up it is regenerated by using high concentrations of the original ions that are exchanged for the polluted ions attached to the resin Flow from regeneration is composed of highly concentrated brine.

Reverse osmosis or ultrafiltration A demineralization process applicable to production of high-quality water from effluent The water permeates

through semipermeable membrane at high pressure, producing high-quality water in one stream and a high concentration of mineral ions in another.

Electrodialysis A demineralization process where electrical potential is used to transfer the ions through ion-selective

membranes Produces two streams; one high in mineral content and the other free of minerals.

pasteurization, cleaning process, equipment, and cooling of

final product The waste is generally characterized by high

BOD and suspended solids The estimated total wastes from

food industry for the United States in 1968 was:

320 million cubic meters of wastewater discharged

360 million kg of BOD generated

180 million kg of suspended solids generated

8 billion kg of solids residuals

Table 4 is a brief summary of major liquid wastes, their origin,

characteristics and applicable methods of treatment for

sev-eral major industries in the food industrial category

Paper and Allied Products Industry

Pulp is produced by mechanically or chemically processing

wood or other vegetative materials to extract usable

cellu-losic fibers as an aqueous slurry The pulp slurry may be used

directly in paper making or it may be shipped elsewhere for

processing into paper products The pulp and paper industry

is the ninth largest industry in the United States The major

group of the industries in the pulp and paper industry are

pulp mills, paper mills, paperboard mills, miscellaneous

converted paper products, paperboard containers and boxes,

and building paper and board mills

The fundamental industrial operations are divided into

two major categories: pulp mill and paper mill The pulp mill

operation includes wood preparation, pulping, deinking, pulp

washing, screening and thickening, and bleaching Paper mill

operations include stock preparation, paper machine

opera-tion, and finishing Table 5 provides a summary of these

operations, origin of major wastes, major characteristics, and

treatment methods

Chemical Industry

The chemical industry is highly diversified and supplies

products for virtually every other industry The number of

synthetic compounds manufactured is estimated to range between 500,000 and 600,000, and a host of new products is introduced every year The chemical products may be used

as primary, intermediate, or finished products

The chemical processing industry has a variety of spe-cial pollution problems due to the vast number of products manufactured The treatment processes combine process-ing, concentration, separation, extraction, by-product recov-ery, destruction, and reduction in concentration The wastes may originate from solvent extraction, acid and caustic wastes, overflows, spills, mechanical losses, etc Origin of major wastes, characteristics, and treatment and disposal of wastes in several major chemical industries are summarized

in Table 6

Petroleum Industry

The petroleum industry is one of the most important manu-facturing industries in the country It is a complex industry utilizing complex combination of interdependent operations engaged in the storage and transportation, separation of crude molecular constituents molecular cracking, molecu-lar rebuilding, and solvent finishing to produce petrochemi-cal products Each process is responsible for production of many waste streams containing oil, chemical oxygen demand (COD), phenol, sulfide, chloride, and others Treatment may involve oil separation, precipitation, adsorption, and biologi-cal treatment The refining operations may be divided into many major categories Wastewater characteristics, origin

of major wastes, characteristics, and treatment and disposal methods from several major processes are summarized in Table 7

Metals Industry

Primary metal processing and fabricated metal products man-ufacturing comprise the metals industries The most important end uses of the products of the metals industries are automo-biles, machinery, appliances, electrical equipment, structures,

THICKENING STABILIZATION CONDITIONING DEWATERING DISPOSAL Concentrates solids Reduces pathogens, and

eliminate offensive odors

Enhances water removal Removes moisture and

produces sludge cake

Used for ultimate disposal of residues

1 Gravity 1 Chlorine oxidation 1 Chemical 1 Vacuum filter 1 Evaporation of brine

2 Flotation 2 Line stabilization 2 Elutriation 2 Filter press 2 Incineration

3 Centrifugation 3 Heat treatment 3 Heat treatment 3 Horizontal belt filter 3 Wet Oxidation

4 Aerobic digestion 4 Centrifugation 4 Pyrolysis

5 Anaerobic digestion 5 Drying beds 5 Composting

6 Land filling

7 Deep well injection

FIGURE 1 Alternative unit operations and processes for sludge and brine processing and disposal.

TABLE 5 Summary of industrial wastes from several major operations in pulp and paper industry

Major Industrial Operations Origin of Major Wastes Major Characteristics Major Treatment and Disposal

Methods Pulp mill

Wood preparation Log transportation and storage,

debarking and chipping

Solid wastes, hydraulic debanking uses water

Incineration, water is recycled through lagoons

Pulping Mechanical pulping, kraft pulping,

sulfide pulping

Suspended solid, BOD, liquors containing high BOD, sulfide, mercaptans, high pH

Sedimentation, recovery if sodium hydroxide and sodium sulfide, aeration

Deinking Removal of ink Contains dirt and clay fillers,

chemicals and usually alkaline

Sedimentation and coagulation

Pulp washing, screening,

and thickening

Washing action, centrifugal cleaning, gravity and vacuum thickening

Liquor contains pulp fibres Pulp fibres are recorded and

recycled Bleaching Bleaching of pulp fibers by chlorine

solution

Contains chlorine, low pH, high TDS

Dechlorination, neutralization

Paper mill

Stock preparation Addition of filter, colors, chemicals,

and screening

Color, clay fillers, chemicals, high TDS

Coagulation and reuse

Paper machine Removal of free water Contains fibres and fillers Known

as white water TSS, TDS and BOD

Fibers reclaimed, liquid wastes treated by coagulation, activated sludge

Finishing and converting Surface improving, size cutting

Mostly dry process

Little or no liquid waste, mainly solid waste

Recycled in pulping operation, incineration

TABLE 4 Summary of industrial wastes from major food industry

Industries Producing Waste Origin of Major Wastes Major Characteristics Major Treatment and Disposal Methods Canned goods Trimming, culling, juicing and

blancing of fruits and vegetables

High in suspended solids, colloidal and dissolved organic matter

Screening, lagooning, soil absorption by spray irrigation

Dairy products Dilutions of whole milk,

buttermilk, and whey

High in dissolved organic matter, mainly protein, fat, and lactose

Biological treatment aeration, RBC, trickling filtration, activate sludge, whey recovery

Brewed and distilled beverages Steeping and pressing of grain;

residue from distillation of alcohol; condensate from stillage evaporation

High in dissolved organic solids, containing nitrogen and fermented starches or their products

Recovery, concentration by centrifugation and evaporation, RBC; trickling filtration; use in feeds; anaerobic biological treatment followed by aerobic biological treatment Meat and poultry products Stockyards; slaughtering of

animals; rendering of bones and fats; residues in condensates; grease and wash water; picking chickens

Organic matter, blood, other proteins, and fats and oils

Screening, settling and/or floatation, trickling filtration, RBC, activated sludge, recovery for animal food products

Animal feedlots Excreta from animals High in organic suspended solids

and BOD

Land disposal and anaerobic lagoons

Beet sugar Transfer, screening, and juicing

waters; drainings from lime sludge; condensates after evaporator; juice and extracted sugar

High in dissolved and suspended organic matter, containing sugar and protein

Reuse of wastes, coagulation, lagooning, activated sludge, trickling filter, anaerobic process

Cane sugar Spillage from extraction,

clarification, evaporation cooling, and condenser waters

Variable pH, soluble organic matter with relatively high BOD of carbonaceous nature

Neutralization, recirculation, chemical treatment, some selected aerobic oxidation

furniture, and containers There are approximately 35,000

establishments in the United States The industry uses

approx-imately 32 billion cubic meters of water per year Four

per-cent of the plants use 92 perper-cent of the water These industries

generate wastewaters which vary in quantity and quality Table 8 provides the reader with a brief summary of the major liquid wastes, their origin, characteristics, and methods of treatment in four major metals industries

TABLE 6 Summary of industrial wastes from several major chemical industries

Industries Producting Wastes Origin of Major Wastes Major Characteristics Major Treatment and Disposal Methods Acids and Alkalies Dilute wash waters; many varied

dilute acids and bases

Low or high pH, low organic content Unflow or straight neutralization,

coagulation and sedimentation Detergents Washing and purifying soaps and

detergents

High in BOD and saponified soaps Flotation and skimming, precipitation

with CaCl2 Explosives Washing TNT and guncotton for

purification, washing and pickling of cartridges

TNT, colored, acid, odorous, and contains organic acids and alcohol from powder and cotton, metals, acid, oils, and soaps

Flotation, chemical Precipitation, biological treatment, aeration, chlorination of TNT, neutralization, adsorption

Pesticides Washing and purification of

products

High organic matter, benzene ring structure, toxic to bacteria and fish, acid

Dilution, storage, activated-carbon adsorption, alkaline chlorination

Phospate and phosporus Washing, screening, floating

rock, condenser bleed-off from phospate reduction plant

Clays, slimes and oils, low pH, high suspended solids, phosphorus, silica and fluoride

Lagooning, mechanical clarification, coagulation and settling of refined waste

Formaldehyde Residues from manufacturing

synthetic resins and from dyeing synthetic fibers

Normally high BOD and formaldehyde, toxic to bacteria in high concentrations

Trickling filtration, absorption on activated charcoal

Plastics and resins Unit operations from polymer

preparation and use; spills and equipment washdowns

Acids, caustic, dissolved organic matter such as phenols, formaldehyde, etc.

Discharge to municipal sewer, reuse, controlled-discharge

Fertilizer Chemical reactions of basic

elements Spills, cooling waters, washing of products, boiler blowdown

Sulfuric, phosphoric, and nitric acids; minerals elements, P, S, N,

K, Al, NH3, NO3

Neutralization, detain for reuse, sedimentation, air stripping of NH3, lime precipitation

Toxic chemicals Leaks, accidental spills, and

refining of chemicals

Various toxic dissolved elements and compounds such as Hg and PCBs

Retention and reuse, change in production, neutralization and precipitation, carbon adsorption

TABLE 7 Summary of wastes generated from various oil refinery operations

Major Industrial Operations Origin of Major Wastes Major Characteristics Major Treatment and Disposal Methods

Crude oil and product storage Primary fractionation of oil and

water, spills and leakages

High concentrations of emulsified oil, COD, TSS

API separation, DAF, settling, aeration

Crude desalting Chemical desalting, heating and

gravity separation of oil

Emulsified and free oil, ammonia, phenol, sulfide, TSS, high BOD and COD

API separation, DAF, activated sludge, carbon adsorption

Cracking Thermal cracking or catalytic

cracking, fractionation, steam stripping, and overhead accumulators or fractionators

BODs, COD, ammonia, phenol, sulfides, cyanides, and alkalinity

Chemical oxidation, biological treatment carbon adsorption

Polymerization Catalytic reaction, acid, removal

action, and gas stabilizer

Alkaline waste stream, high in sulfide, mecaptans, and ammonia

Acid catalysts recycled, carbon adsorption

Alkylation Catalytic reaction caustic and

water wastes, neutralization of hydrocarbon streams

Oil, sulfides, TSS, fluoride Neutralization, chemical oxidation,

sedimentation