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Module 6: EFFLUENT TREATMENT AND RESIDUALS MANAGEMENT

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Title: Module 6: EFFLUENT TREATMENT AND RESIDUALS MANAGEMENT


1
Module 6EFFLUENT TREATMENT AND RESIDUALS
MANAGEMENT
  • Program for North American Mobility in Higher
    Education

2
Structure of this module
  • This module is divided into 3 tiers, each with
    a specific goal
  • Tier 1.- Basic introduction
  • Tier 2.- Case study of the pulp paper sector
  • Tier 3.- Open-ended problem

3
Tier 1. Contents
  • Introduction
  • Industrial pollution problems.
  • The petroleum industry.
  • The pulp and paper industry.
  • Programs for reducing pollution.
  • Treatment processes.
  • Process selection.
  • Volume and disposal reduction.

4
Effluent Treatment and Residuals Management
Tier I Introductory concepts
Tier 1
5
G o a l s
  • To provide information about the significance of
    treating effluents from industry and others
    facilities (or sources)
  • To extreme the necessity of minimize pollutant
    concentration in the effluents and reduce the
    wastes production, and,
  • To suggest strategies to reduce pollutant wastes
    production and their emission to the environment

Tier 1
6
What is pollution?
  • Pollution means
  • changes in the physical, chemical and
    biological characteristics of air, land and water
  • harms for the human and other living species,
    and,
  • degradation of the ecosystems
  • ...the undesirable state of the natural
    environment being contaminated with harmful
    substances as a consequence of human activities
  • For example, Water Pollution refers to
    contaminants in aquatic ecosystems (streams,
    lakes, etc) which render them unfit for a
    particular use.

Tier 1
7
Pollutants can reach
  • Air
  • Water
  • Solid waste
  • This module focuses on water pollution from
    industrial sources

Tier 1
8
Water standards
  • Drinkable
  • Recreation swimming, fishing.
  • Irrigation
  • Water impurities may or may not be harmful it
    depends on
  • The amounts and nature of these impurities,
  • The next use to which the water will be put, and
  • The tolerance of these impurities for the next
    use.

Tier 1
9
Types and characteristics of wastewaters
Contaminants Reason for importance
Physical suspended solids They can lead to the development of sludge deposits.
Chemical biodegradable organics When discharged untreated to the environment, they lead to the depletion of natural oxygen resources.
Nutrients If discharged, they can lead to water pollution.
Hazardous Because of their characteristics (e.g.,toxicity, flammability) are dangerous for human health and the environment.
Heavy metals They can negatively impact upon biological waste treatment processes.
Dissolved inorganic solids They are result of water use, and may have to be removed if the wastewater is to be reused.
Biological pathogens Communicable diseases can be transmitted by the pathogenic organism in wastewater.

Tier 1
10
Water standards
Industrial effluent standards Industrial effluent standards Industrial effluent standards Industrial effluent standards
Parameter Mexico a USA b Canada c
Total suspended solids, (mg/l) 150 27 15
BOD5, (mg/l) 20 56 15
pH 5-10 6-9 6-10.5
Tier 1
11
Tier 1
12
What is BOD?
  • By definition, BOD is the quantity of oxygen
    required for the stabilization of the oxidizable
    organic matter present over 5 days
    of incubation at 20 oC that
    can be explained as a measure of the oxygen
    required by microbes to degrade a sample of
    effluent.
  • The organic content of the water can be estimated
    by the BOD.

Tier 1
13
Why should we minimize the use of water?
  • Water is such an important part of many
    manufacturing processes that we must consider
    Effluent Treatment as a part of the main process
    because of the great amount always involved.
  • Water is abstracted from aquifers and rivers,
    treated and supply to industries and homes for
    different uses used water is supposed to be
    treated and discharged again into the rivers.
    Most of the times, this water returns to its
    natural environment but unfortunately, with a
    greater heat content or with some substances
    added.

Tier 1
14
Why should we minimize the use of water?
  • It is also important to minimize use of water
    because of several reasons
  • Fresh water is often scarce. High costs involved
    operating effluent treatment plants.
  • Difficult to separate all the elements that
    pollute water.

Tier 1
15
Industrial pollution problems
Tier 1
16
Industrial pollution problems
  • The main pollution problems are related to
  • Increasing use of water for agriculture.
  • The increase of aqueous effluent to receiving
    water.
  • Population growth.
  • Industrial products and services.
  • The mental, technical, financial, regulatory and
    institutional barriers to implement preventive
    modern technologies.
  • RESULTS
  • Ecosystems decline.
  • Industrialization social costs.
  • The increase of human diseases.

Tier 1
17
The petroleum industry
Tier 1
18
The Petroleum Industry
  • Crude oil refining operations involve extracting
    useful petroleum products from crude oil. Crude
    oil contains fractions of napthas, gasoline, gas
    oils, diesel fuel, asphalt, jet fuel and
    lubrication fuels.
  • Large quantities of production wastes are
    produced during exploration and production
  • Wastewater
  • Solid waste
  • Toxic pollutants

Tier 1
19
The Petroleum Industry
  • Production wastes in the petroleum industry can
    be grouped broadly into 2 classes
  • Wastes related to drilling including chemical
    additives treatment and disposal of oil
    drilling wastes takes place either on or off the
    drilling site.
  • Wastes related to oil production, primarily
    produced water
  • The volume of produced water exceeds the volume
    of drilled wastes.
  • If environmental quality standards are not
    exceeded the remainder may be discharged to
    surface waters. The majority of produced water is
    disposed of underground through injection wells
    and it is permitted under U.S. EPA control
    programs.

Tier 1
20
What is refinery effluent?
  • Petroleum refineries use large volumes of water
    in their processes.
  • The wastewater contains hazardous chemicals

Tier 1
21
Refinery wastes
  • Emissions from refineries include
  • Sulfur oxides
  • Nitrogen oxides
  • Benzene, toluene and xylene
  • VOC
  • Wastewater containing BOD levels
  • Heavy metals

Tier 1
22
Wastes generated
Tier 1
(Pollution Prevention and Abatement Handbook
World Bank Group)
23
The pulp and paper industry
Tier 1
24
How paper is made
  • Most of the raw material needed for paper
    manufacture is supplied by trees.
  • The main steps in the pulp and paper manufacture
    are raw material preparation, such as wood
    debarking, and chip making pulp manufacturing
    pulp bleaching paper manufacturing and fiber
    recycling. Pulp mills and paper mills may exist
    separately or as integrated operations.
  • The characteristics of the paper (smoothness,
    glazed finish) are given by a process called
    calendering.
  • The paper undergo coating, whereby a thin layer
    of coating pigment or filler is spread onto the
    paper surface.

Tier 1
25
Pulp and paper industry
  • The pulp and paper industry has made significant
    steps toward conserving water and energy.
  • Significant water reductions are achieved through
    better reuse methods and by separating cooling
    water from process water.
  • The waste streams generated in this industry are
    best classified by their origins as show in the
    next slide.

Tier 1
26
Types of waste products in the pulp and paper
industry
  • Material originated in raw materials (dirt and
    bark with wood).
  • Nonfiber components in wood.
  • Contaminants in waste paper and make-up
    chemicals.
  • Reaction products (dissolved wood substance from
    mechanical or chemical action).
  • Fiber fragments.
  • By-products of chemical recovery and combustion.
  • Fiber and nonfiber process looses and discharges
    of water, air and heat.

Tier 1
27
The pulp and paper industry
  • Water use and effluent discharges
  • Liquids discharges from the process contain
    solids, mainly fiber, fillers, and colloidal and
    dissolved material. The fiber and fillers are
    minimized and reused. Colloidal and dissolved
    materials are by-products of the refining of the
    fibers or carried over from the pulp mill.
  • Discharges of dissolved material are minimized by
    washing the stock and displaced carryover from
    pulp mills and by practicing good water reuse
    strategies that reduce the volume and
    concentrations of waste in wastewater.

Tier 1
28
Programs for reducing pollution
Tier 1
29
Government programs for reducing pollution
  • For sustainable development, governmental
    pollution prevention programs can best counteract
    the pressure to invest in end of pipe pollution
    solutions by demonstrating the economic and
    environmental benefits of a source reduction
    approach, making technical information available
    and providing technical assistance.
  • EPA has been working with industry and government
    representing environmental, community and work
    force issues to prevent pollution at the source
    prior to end of pipe treatment.

Tier 1
30
Government programs for reducing pollution
  • Laws such as NEPA, TCSA, CAAA and PPA remain
    outside the scope of most pollution control work.
    The following options were suggested for USEPA
    for moving forward interaction in the US
  • Add multi-media provisions to the existing
    regulations.
  • Correct laws in other policy sectors with
    environmental measures.
  • Make NEPA a stronger statute.
  • Make TSCA a law which can use EPA programs to
    control and reduce toxic substances.
  • Establish pollution prevention approaches.

Tier 1
31
Programs for reducing pollution
  • Manufacturers could implement a variety of
  • improved management procedures
  • that would aid pollution reduction
  • Environmental audits. Identify (inventory) and
    correct problems (strategies to achieve
    reductions) that generate wastes.
  • Regular preventive maintenance. Inspection,
    maintenance and replacement of equipment.
  • Material handling and storage. Emissions of
    hazardous material must be avoided. There should
    be labels of all containers and first aid
    recommendations.
  • Employee training. Well informed employees are
    better able to make valuable waste reduction
    suggestion.
  • Operating manual and record keeping. Good
    facility documentation process procedures,
    control parameters, hazards and operator
    responsibilities.

Tier 1
32
Environmental programs
  • Some industries may see no difference between end
    of pipe pollution control and a front end
    pollution prevention control.
  • The importance is that those industries may not
    go beyond the first stage of waste reduction.
  • As the environmental concern deepens, industries
    have to move further up the production chain
  • End of pipe solution to wastes and pollutants
    and later
  • Internal process modifications to reduce
    emissions and wastes, and eventually
  • Redesign products to achieve a maximum level of
    recycling of raw materials and minimization of
    wastes after the products are used.

Tier 1
33
Some measurements to save water
  • Keep water effluent streams separated.
  • Reuse water as close to source as possible.
  • Recycling whenever it is possible.
  • Better control of usage with automated systems.
  • Checking and control of leaks.
  • When buying new equipment, evaluate
    water-efficiency models including accessories.
  • Reducing the quantities of chemicals so that the
    amount of dilution water will be reduced.

Tier 1
34
Reusing water
  • It is not only possible but necessary to reuse
    wastewater of a process stream before it leaves
    the plant accomplished by piping, diluting or
    treating some of the effluents before using them
    again.
  • Some plants are now using closed systems, so that
    there are no water discharges.
  • Zero discharges has been practiced in locations
    where water is scarce, and may involve
    technologies for removing suspended and dissolved
    solids.
  • Complete demineralization is relatively
    expensive, however, in some cases wastewater
    discharges can be reduced significantly with
    other less expensive technologies.

Tier 1
35
Treatment processes
Tier 1
36
Expectations of a water treatment program
  • The expectations from a water treatment program
    should be integrated to include all aspects of
    the program, from the proposal through to the
    implementation stages.

Tier 1
37
Treatment Program
  • As we will see in the next diagram, the
    expectations that a good treatment program should
    give us are listed below
  • Overview of a new or existent problem.
  • Lab study of all system and water composition.
  • Submit a proposal.
  • Program implementation.
  • Monitoring to optimize.
  • Use of modern treatment techniques.

Program under control
Tier 1
38
Treatment Program
New or Problem System
Plant Study
Proposal
Implement Program
System under control
Lab Study
Follow-up
New Product Technology
Tier 1
39
Wastewater treatment processes
  • Wastes are generated by every industrial
    enterprise, and this wastes can either be liquids
    or solids.
  • Wastewater treatment can be divided into three
    stages
  • Primary treatment that uses physical operations
    to remove free oil and/or suspended solids.
  • Secondary treatment to remove dissolved
    contaminants through chemical or biological
    action, and
  • Tertiary treatment for the removal of residual
    contaminants.

Tier 1
40
Separation order
  • This list shows how separation is carried out
  • Primary treatment
  • Sedimentation
  • Aeration
  • Secondary treatment
  • Tertiary treatment

Tier 1
41
Treatments
  • Primary treatment prepares the wastewater for
    biological treatment. Large solids are removed by
    screening, and grit. Equalization in a mixing
    basin, levels out the flows variation and
    concentrations. Neutralization, where required,
    follows equalization. Oils, greases and suspended
    solids are removed by flotation, sedimentation of
    filtration.
  • Secondary treatment is a biological degradation
    of soluble organic compounds from input levels of
    50- 1000 mg/l BOD or greater to effluent levels
    under 15 mg/l. Aerobic treatment in an open
    vessel is done. After biotreatment, the
    microorganisms and solids suspended are allowed
    to settle.

Tier 1
42
Treatments
  • The tertiary treatment remove specific residuals.
    By filtration, suspended colloidal solids can be
    removed adsorption removes organics by granular
    activated carbon (GAC) and chemical oxidation
    also removes organic compounds.
  • Tertiary systems have to treat great amounts
    of wastewater, so they are expensive.
  • When streams rich in heavy metals, pesticides or
    other substances that may pass through primary
    treatment and inhibit biological treatment are
    present, in-plant treatments are necessary.
  • Precipitation, activated carbon adsorption,
    chemical oxidation, air or steam stripping, wet
    air oxidation, ion exchange, reverse osmosis are
    some of the methods useful when in-plant
    treatments are to be used.

Tier 1
43
The tertiary treatment
  • Tertiary treatment is a polishing step. Its
    importance is that rather than have to find
    solutions at the end of pipe, where primary and
    secondary treatments are used to, it is possible
    to minimize some toxics or hazardous components
    in the process before they are combined with
    other less hazardous.
  • Biological treatment usually produces a 30/20
    effluent with no more than 30 mg/l suspended
    solids and 20 mg/l BOD.

Tier 1
44
Tertiary treatment
  • However, river flows have decreased owing to
    drought conditions. In these circumstances, new
    limits are imposed on the quality of the final
    effluent. The treatment processes beyond the
    secondary treatment to achieve the required
    limits in the process are well known as tertiary
    treatments.

Tier 1
45
In plant treatment
  • Before end of pipe wastewater treatment, a
    program of waste minimization should be
    initiated.
  • Recirculation. In the paper board industry, white
    water from a paper machine can be put through a
    save all to remove the pulp and fiber and
    recycled to various points in the process.
  • Segregation. Clean streams are separated for
    direct discharge.
  • Disposal. In many cases, the total discharge BOD
    and suspended solids can be reduced by removal of
    residue in semidry state for disposal.
  • Reduction. The use of automatic cutoffs can
    reduce the wastewater volume.
  • Substitution. The substitution of chemical
    additives of a lower pollutional effect in
    processing operations.

Tier 1
46
Wastewater treatment processesProcess selection
  • .

Tier 1
47
Figure 1. Conceptual treatment program for
organic and toxic industrial wastewater
For wastewaters containing nontoxic organics,
process design criteria can be obtained from lab
studies.
To define the wastewater treatment problems, a
preliminary analysis should be carried out
Organic streams
Streams containing heavy metals
Mineral streams
Toxic and/or nonbiodegradable
volatile
Biodegradable
Source control Figure 3.
Equalization Neutralization Oil/grease
removal Suspended solids
Biological treatment
Final disposal
Tier 1
(Eckenfelder, 2000)
48
Source treatment
goal
  • Source reduction is any activity that reduces or
    eliminates the generation of hazardous wastes at
    the source
  • The fundamental goal is to enact changes in
    consumption, use and waste generation patterns
    associated with products

Tier 1
49
Source treatment
  • Source treatments involves different definitions
    of source reduction, but the general consensus
    appears to be that include any in-plant actions
    to reduce the quantity or the toxicity of the
    waste at the source.
  • Examples include equipment modification, design
    and operations changes of the process and
    products and substitution of raw materials.

Tier 1
50
Figure 2. Laboratory studies for heavy
metals/volatile organics
start
Air or steam stripping
VOC/NH3
Equalized sample
Chemical oxidation reduction
Priority pollutants scan and bioassay
Precipitation
Heavy metals
When toxic and nontoxic organics and inorganics
are present, it is necessary to evaluate the
existence of heavy metals or volatile organics.
Nondegradable/ toxic
Fed batch reactor
Source treatment
Degradable
Long-term biodegradation
Granular activated carbon
Reverse osmosis
Priority pollutants scan and bioassay
Powder activated carbon
Priority pollutants/toxic
Ion exchange
TDS/inorganics
Tier 1
(Eckenfelder, 2000)
51
Figure 3. Treatment of toxic wastewaterIn-plant
treatment
To discharge recycle or treatment
Reverse osmosis
If the wastewater is nonbiodegradable or toxic,
it should be considered source treatment or
in-plant modification.
Ion exchange
Polymeric resins
Granular carbon adsorption
Filtration
Anaerobic treatment
Precipitation
Oxidation reduction
Wet air oxidation
Air or steam stripping
Chemical oxidation
Volatile organics ammonia
Process wastewater
Heavy metals
Organic chemicals
Tier 1
(Eckenfelder, 2000)
52
Methods for suspended solids removal
  • Sedimentation is the more common technique in
    wastewater treatment because it involves little
    mechanical equipment and it is very stable to
    operate. However, there are some situations where
    flotation is a better choice.
  • Flotation is a good technique for solids removal
    when the density difference between water and the
    solids is marginal, or the solids have a high fat
    or oil content.

Tier 1
53
Methods for suspended solids removal
  • Coagulation is employed for removal of waste
    materials in suspended or colloidal form.
    Colloids are particles within the size range of 1
    nm to 0.1 nm, do not settle out on standing and
    can not be removed by conventional physical
    treatment processes.
  • Precipitation. In the water treatment, the
    precipitation process is used for softening
    (removal of the hardness caused by calcium and
    magnesium) and removal of iron and manganese.

Tier 1
54
Sedimentation
  • Reduce solids by at least 50, with proportional
    reduce of BOD.
  • Addition of chemicals to assist settlement by
    coagulating particles or chemical precipitation
    can be essential.
  • Can have acceptable discharge standards with
    regular desludging without a secondary treatment.
  • Primary tanks are desludged at intervals of
    between 8 and 24 hours.
  • Secondary settlement follows any form of
    biological aeration or filtration to produce an
    effluent low in solids.
  • Particularly demanding discharge consents may
    dictate a tertiary treatment to remove solids and
    BOD by a further 50.

Tier 1
55
Flotation
  • Dissolved air flotation, which is a common
    technique. This technique basically consists on
    injecting an aqueous stream containing dissolved
    air into the wastewater . The dissolved air forms
    bubbles when it comes out of solution and carries
    suspended particles, which tend to concentrate at
    the bubble wastewater interface, to the surface,
    where they form an emulsion.

Tier 1
56
Flotation
General diagram for flotation methods
Tier 1
57
Coagulation
  • Paperboards wastes can be effectively coagulated
    with low dosages of alum. Silica or
    polyelectrolyte will aid in the formation of a
    rapid settling floc.
  • Wastes that contain emulsified oil can also be
    clarified by coagulation.
  • For effective coagulation, alkalinity should
    first be added, . After addition of alkali and
    coagulant, a rapid mixing is recommended.

Tier 1
58
Precipitation
  • Chemical precipitation in wastewater treatment
    involves the addition of chemicals to alter the
    physical and chemical state of dissolved and
    suspended material and to facilitate their
    removal. It is usually combined with coagulation,
    flocculation, separation.
  • Principle Dissolved compounds, for instance
    heavy metal ions, are brought into their
    insoluble hydroxides by pH increase through
    dosing of lime or NaOH. Using coagulation,
    flocculation techniques these small hydroxide
    nuclei become larger flocs for separation. With
    proper precipitants these flocs also serve as
    entrapment for other dissolved (organic)
    compounds a form of co-precipitation.

Tier 1
59
Heavy Metals Removal
HEAVY METALS REMOVAL TECHNOLOGIES
Conventional precipitation
Hydroxide
Sulfide
carbonate
coprecipitation
Enhanced precipitation
Dimethyl thio carbamate
Diethyl thio carbamate
Trimercapto-s-triazine, trisodium salt
Other methods
Ion exchange
Adsorption
Recovery opportunities
Ion exchange
Membranes
Electrolytic techniques
Tier 1
60
The Biological Treatment
When biological treatment is needed, there are
several options
Influent wastewater
High strength
Yes
Yes
No
Physical and chemical treatment
High strength
Anaerobic treatment
Biodegradable
Yes
Polished effluent
Inhibitory Nondegradable fraction
Yes
No
Discharge
PACT
No
Discharge
Nitrogen
Complete mix system
Dispersed growth system
Readily degradable
No
No
No
removal required
Fixed Growth system
Yes
Yes
Intermittent process
Plug flow system
Selector system
Nitrification/ Denitrification system
Yes
Polished effluent
No
Discharge
Discharge
Tier 1
(Eckenfelder, 2000)
61
The biological treatment typical operating
parameters and dimensions
Treatment method Mode of operation Degree of treatment Land requirements Equipment Remarks
Lagoon Intermittent or continuous discharge facultative or anaerobic Intermediate Earth dug 10-60 days retention Odor control frequently required
Activated lagoons Completely mixed or facultative continuous basins High in summer less in winter Earth basin, 8-16 ft deep, 8-16 acres/(million gal/d) Pier-mounted or floating surface aerators or subsurface diffusers Solids separation in lagoon periodic dewatering and sludge removal
Activated sludge Completely mixed or plug flow sludge recycle gt 90 removal of organics Earth or concrete basin 12p20 ft deep 75000-350000ft3/(million gal/d) Diffused or mechanical aerators clarifier for sludge separation and recycle Excess sludge dewatered and disposed of
Trickling filter Continuous application may employ effluent recycle Intermediate or high, depending on loading 225-1400 ft /(million gal/d) Plastic packing 20-40 ft deep Pretreatment before POTW or activated sludge plant
RBC Multistage continuous Intermediate or high Plastic disks Solids separation required
Anaerobic Complete mix with recycle upflow or downflow filter, fluidized bed upflow sludge blanket Intermediate Gas collection required pretreatment before POTW or activated sludge plant
Spray irrigation Intermittent application of waste Complete water percolation into groundwater and runoff to stream 40-300 gal/(min.acre) Aluminum irrigation pipe and spray nozzles movable for relocation Solids separation required salt content in waste limited
Tier 1
(Eckenfelder, 2000)
62
Advanced wastewater treatments
  • Advanced wastewater treatment is defined as the
    processes that remove more pollutants from
    wastewater than the conventional treatments. This
    term may be applied usually as tertiary
    treatment, but most of their goals are to remove
    nitrogen, phosphorus, and suspended solids.
  • Advanced treatments include
  • Chemical coagulation of wastewater
  • Granular media filters
  • Ultrafiltration
  • Nanofiltration
  • Wedge-wire screens
  • Microscreening
  • Diatomaceous earth filters

Tier 1
63
Volume and disposal reduction
Tier 1
64
Volume reduction
  • Volume reduction can be used to reduce treatment
    cost and to reduce handling and disposal costs
    for residues remaining after treatment. Volume
    reduction can be accomplished by using a variety
    of methods
  • Reuse of treated wastewater and wastes
  • Treatment modifications to reduce solid residues
  • Segregated treatments to reduce hazardous waste
    mixtures
  • Incineration to reduce waste volume and to render
    a hazardous waste nonhazardous.

Tier 1
65
Reduction of waste production and disposal
volumes
  • Simple dewatering the sludge is discharged into
    a series of tanks and allowed to settle. Top
    water can then be decanted. This method reduce
    the volume of sludge for disposal.
  • Composting the material is mechanically turned
    at intervals, force aerated and often contained
    in a building where heat losses, odor and water
    content can be controlled.

Tier 1
66
Reduction of waste production and disposal
volumes
  • Digestion is the slow degeneration of the
    organic content of sludge by obligate anaerobic
    bacteria to simpler compounds- carbon dioxide,
    water and anions (nitrate, sulphate, phosphate).
  • Digestion is one of the few sludge treatment
    processes in which a significant reduction of
    pathogens is possible.
  • The digestor gas produced is 65-70 methane,
    30-34 carbon dioxide, and traces of sulphur
    compounds. The collected gas is burnt in a boiler
    to keep the digestor warm and the excess put to
    further heating or power generation purposes.

Tier 1
67
Reduction of waste production and disposal
volumes
  • Incineration its main advantages lie in the
    complete destruction of organic compounds, the
    ash being inert and usually less than 25 of the
    original sludge volume.
  • Most incinerators are of the fluidized bed
    variety.

Tier 1
68
A waste management diagram
Waste recycle
Upgrade operation
Waste treatment
Redesign process
Increasing Effectiveness of waste management
Waste disposal
Substitute raw material
Tier 1
69
Multiple choice questions
Tier 1
70
Tier 1 Quiz
  • 1. What is pollution?
  • Pollution refers to harmful environmental
    contaminants and to the act or process of
    polluting the environment.
  • Any undesirable change in the characteristics of
    the air, water, soil or food that can affect the
    health called pollution.
  • Unwanted chemicals or other materials found in
    the environment. Pollutants can harm human
    health, the environment, and property.
  • All of the above.

Tier 1
71
Tier 1 Quiz
  • 2. What is BOD?
  • The quantity of oxygen required for the
    stabilization of the oxidizable organic matter
    present over 7 days of incubation at 20 oF.
  • An empirical test used for measuring waste,
    evaluating the measure of the oxygen required by
    microbes to degrade a sample of effluent.
  • A test used to evaluate the quantity of oxygen
    present in the stream.
  • The quantity of oxygen required to develop a
    biochemical test.

Tier 1
72
Tier 1 Quiz
  • 3. Why is it important to reduce hazardous
    contaminants?
  • Because if discharged, they can lead to water
    pollution.
  • Because of its radioactive characteristics, its
    effects on human health and development of
    cancer.
  • Communicable diseases can be transmitted when in
    contact to them.
  • Because of their dangerous characteristics for
    human health and the environment.

Tier 1
73
Tier 1 Quiz
Tier 1
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