Water Treatment Plant Residue Management Modification

8/13/2019 Water Treatment Plant Residue Management Modification

1/33

WATER TREATMENT

PLANT RESIDUE

MANAGEMENT

ALAN ANTONYI Semester MTech

Environmental Engineering

VNIT


2/33

CONTENTS

Introduction

What is residual management plan?

Different categories of residuals inwater treatment

Sources of residues

ProcessMethods of disposals

Chemical recovery


3/33

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


4/33

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.


5/33

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


6/33

RESIDUAL SOURCES


7/33

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.


8/33

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.


9/33

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


10/33

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.


11/33

TECHNOLOGIES AND

PRACTICES FOR

PREVENTING, TREATING,

DISPOSING OF, AND

DISCHARGING SOURCE

WATER TREATMENTRESIDUALS


12/33

BMPs.

Pollution prevention and waste

reduction.Residuals treatment.

Disposal of wastes.

Discharge of wastes.


13/33

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.


14/33

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.


15/33


16/33

RESIDUAL HANDLING

PROCESSES

Thickening

Conditioning

Dewatering

Drying

Disposal and Reuse

Coagulant recovery


17/33

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


18/33


19/33

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.


20/33

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.


21/33

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.


22/33


23/33

Mechanical Dewatering

Processes

Belt Filter Presses

Sludge sandwiched between two

porous belts is passed over and underrollers of various diameters


24/33


25/33

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.


26/33


27/33

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


28/33

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


29/33


30/33

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.


31/33

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.


32/33

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


33/33

THANK YOU

Documents

Water Treatment Plant Residue Management Modification