Module 6: EFFLUENT TREATMENT AND RESIDUALS MANAGEMENT

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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

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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.

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Effluent Treatment and Residuals Management
Tier I Introductory concepts
Tier 1
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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

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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.

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Pollutants can reach

• Air
• Water
• Solid waste
• This module focuses on water pollution from
  industrial sources

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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.

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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.

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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
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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.

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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.

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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.

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Industrial pollution problems
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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.

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The petroleum industry
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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

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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.

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What is refinery effluent?

• Petroleum refineries use large volumes of water
  in their processes.
• The wastewater contains hazardous chemicals

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Refinery wastes

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

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Wastes generated
Tier 1
(Pollution Prevention and Abatement Handbook
World Bank Group)
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The pulp and paper industry
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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.

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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.

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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.

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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.

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Programs for reducing pollution
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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.

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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.

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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.

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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.

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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.

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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.

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Treatment processes
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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.

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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
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Treatment Program
New or Problem System
Plant Study
Proposal
Implement Program
System under control
Lab Study
Follow-up
New Product Technology
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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.

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Separation order

• This list shows how separation is carried out
• Primary treatment
• Sedimentation
• Aeration
• Secondary treatment
• Tertiary treatment

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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.

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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.

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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.

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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.

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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.

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Wastewater treatment processesProcess selection

• .

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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
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(Eckenfelder, 2000)
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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

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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.

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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
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(Eckenfelder, 2000)
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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
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(Eckenfelder, 2000)
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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.

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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.

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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.

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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.

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Flotation
General diagram for flotation methods
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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.

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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.

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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
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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)
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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)
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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

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Volume and disposal reduction
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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.

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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.

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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.

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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.

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A waste management diagram
Waste recycle
Upgrade operation
Waste treatment
Redesign process
Increasing Effectiveness of waste management
Waste disposal
Substitute raw material
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Multiple choice questions
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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.

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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.

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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.

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Tier 1 Quiz
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