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WATER TREATMENT
PLANT RESIDUE
MANAGEMENT
ALAN ANTONYI Semester MTech
Environmental Engineering
VNIT
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CONTENTS
Introduction
What is residual management plan?
Different categories of residuals inwater treatment
Sources of residues
ProcessMethods of disposals
Chemical recovery
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RESIDUALS
Unwanted waste materials removed from
water
Compounds created by the addition of
chemicals at different stages of treatment
such as floc, lime solids etc
Organic and inorganic compounds in
gaseous, liquid and solid forms
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What is residual management plan?
Characterize form, quantity, and quality
of the residuals.
Determine appropriate regulatory requirements.
Identify feasible disposal options.
Select appropriate residuals processing/
treatment technologies.
Develop a residuals management strategy thatmeets both the economic and noneconomic
goals established for a water treatment facility.
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RESIDUAL CATEGORIESSludge waste produced in sedimentation basins in
conventional coagulation-filtration plants or lime softeningplants
Spent filter back wash water that has been used to cleanfilters in conventional or softening plants
Membrane concentrateliquid waste consisting ofcontaminants rejected by the membrane and any additivesapplied before membrane treatment
Brine residualsliquid waste similar to the concentrategenerated by the desalination membrane operations butproduced by the ion exchange process
Spent carbon - carbon that has exceeded its useful life asadsorbent
Off gaseswaste produced by air stripping facilities thatreleases vapour to the atmosphere
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RESIDUAL SOURCES
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TREATMENT PROCESSES AND
RESIDUES PRODUCED
PRE SEDIMENTATION The residues generated consist of clays, silts,
sands, and other heavy settleable materials
present in the raw water.
COAGULATION, FLOCCULATION, AND
SEDIMENTATION
coagulant metal hydroxides along with source
water natural organic matter, suspended solids,microorganisms, radionuclides, and other
organic and inorganic constituents.
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Contd.
Moisture content : (97 to 99.5%)
Color : varies from light brown to black
Feathery, bulky, and gelatinous.
requires additional processing such as thickening,dewatering, or drying prior to disposal.
difficult to dewater.
LIME SOFTENING calcium carbonate (85 to 95% total solids)
hydroxide of magnesium, aluminium, and othermetals.
clay and silt particles.
minor amounts of unreacted lime .
inorganic and organic matter.
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Contd..
FILTRATION clay and silt
microorganisms (bacteria, viruses, and protozoan cysts)
colloidal and precipitated humic substances
natural organic particulates from the decay ofvegetation.
ION EXCHANGE
Calcium and mg ions, also removes nitrates, barium,
radium, arsenate, selenite, excess levels of fluoride, lead,
and chromate
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Contd..
ACTIVATED CARBON removes ions or molecules from the source water by
adsorbing the chemicals in the source water onto the
treatment media
remove naturally occurring organic materials, taste, odor,synthetic organic compounds, as well as disinfection by-
products
Residuals generated by GAC include backwash water (or
surface wash water) and spent media.
Backwash water generally contains the removed contaminants
such as suspended solids, biological films, organics, and some
filter media.
The spent media (or carbon) is sent off site for regeneration or
disposal.
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TECHNOLOGIES AND
PRACTICES FOR
PREVENTING, TREATING,
DISPOSING OF, AND
DISCHARGING SOURCE
WATER TREATMENTRESIDUALS
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BMPs.
Pollution prevention and waste
reduction.Residuals treatment.
Disposal of wastes.
Discharge of wastes.
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ZERO DISCHARGE STATUS
Generate residues but do not discharge
multiple benefits such as water conservation,
environmental improvements, and cost
reduction. Achieved by a combination of pollution
prevention/waste management and residuals
treatment practices, such as recycling,
evaporation, composting, landfill disposal, spray
irrigation, underground injection, and land
application.
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POLLUTION PREVENTION
AND WASTE REDUCTION Optimizing source water intake conditions to reduce
suspended solids and thereby reduce source water
treatment requirements.
Optimizing filter media for finished water and residuals.
Optimizing pH to reduce coagulant chemicals used.
Reducing softening chemicals used by frequent monitoring
of source water hardness.
Returning backwash water and filter-to-waste to the head
of the source water treatment plant for reuse. Reusing precipitative softening chemicals by recycling
softening residuals.
Recovering treatment chemicals.
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RESIDUAL HANDLING
PROCESSES
Thickening
Conditioning
Dewatering
Drying
Disposal and Reuse
Coagulant recovery
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THICKENING
increase the solids content of the residuals by removing a
portion of the water
1. Gravity thickener
2. Floatation thickener
3. Gravity belt thickener
Gravity Thickener
carbonate and metallic hydroxide residuals areconveyed to gravity settling tanks at a flow rate that allows
the residuals sufficient retention time to settle
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CONDITIONING
Chemical conditioning
This conditioning involves the addition
of ferric chloride, lime, or polymer
Physical conditioning
1.Freeze-thaw conditioning:
This process may be accomplishedthrough either an open-air process in cold
weather climates or through mechanical
equipment.
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Contd..
2. Thermal conditioning: Thermal conditioning at high
temperatures (350F to 400F) under
high pressure
Effective when there is a high organic
content present in the solids.
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DEWATERINGStorage Ponds and Lagoons
Can be used for storage, thickening,
dewatering, or drying.
Final residual disposal
Sand drying beds
dewater residuals by gravity drainage,followed by evaporation. Water drainsthrough the sand and exits through theunder-drain.
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Mechanical Dewatering
Processes
Belt Filter Presses
Sludge sandwiched between two
porous belts is passed over and underrollers of various diameters
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CENTRIFUGE
A process that uses the force developed by
fast rotation of a cylindrical bowl to
separate solids from liquids.
When a mixture of solids and water
enters the centrifuge, it is forced against
the bowls interior walls, forming a pool of
liquid that separates into two distinctlayers.
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DISPOSAL
The most common methods of WTP
residuals disposal used in the water
industry are
Land application
Land filling
Direct stream discharge Discharge to the sewers
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CHEMICAL RECOVERY
Coagulant Recovery
Extracting aluminum or iron coagulantsfrom the waste stream.
Extraction is achieved by acidification
Extraction pH is typically in the range of1.8 to 3.0.
Acid contact time of 10 to 20 minutes
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Water Treatment Plant Residuals
for Use in Storm-Water Control Measures
Sustainable alternative to landfill disposal of WTRs. The incorporation of residuals into SCMs may
provide additional water quality improvements
Aluminum-based coagulants are commonly used in
water treatment systems aluminum-based water treatment residuals (Al-WTR)
are effective at removing phosphate at
concentrations found in storm-water runoff.
In addition to research has shown that WTRs have
the potential to remove a variety of other
contaminants from water. These contaminants
include cadmium, lead , zinc, arsenic, mercury,
perchlorate and fluoride.
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CONTD
Hydraulic conductivity of the residuals Are modified by heating
it in elevated temperature
1. drying at 105C for at least 24 h
2. Baking at 1,000C.
1,000C was chosen because increases in temperature
have been shown to transform amorphous aluminum
hydroxide to more thermodynamically stable phases
minimize leaching from WTRs.
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REFERENCES
Drinking Water Treatment Plant ResidualsManagement Technical Report (EPA 2011)
ASCE, 1996. Technology Transfer Handbook:Management of Water Treatment PlantResiduals, ASCE and AWWA Ed. NY.
Tech Brief : Water Treatment Plant ResidualsManagement,
Feasibility Study of As-Received and Modified
(Dried/Baked) Water Treatment Plant Residualsfor Use in Storm-Water Control Measures (JohnKomlos1; Andrea Welker, M.ASCE2; Vito Punzi3;and Robert Traver, M.ASCE4) (ASCE JOURNAL)
http://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/residuals_management_report.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/residuals_management_report.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/(asce)ee.1943-7870.0000737%20112.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/residuals_management_report.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/residuals_management_report.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/residuals_management_report.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/residuals_management_report.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/residuals_management_report.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_9/water%20treatment%20seminar/RELAVANT/residuals_management_report.pdf -
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THANK YOU