ion exchange in water treatment-drinking water production

8/7/2019 ion exchange in water treatment-drinking water production

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11.03.2011 1ChE-332 FUND.& APP. OF ION EXCHANGE TECH.


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CONTENTS

GENERAL INFORMATION ABOUT

DRINKING WATER

DRINKING WATER CONTAMINANTS

DRINKING WATER TREATMENT

ION EXCHANGE

WATER SOFTENING

WATER DEIONIZING

ION EXCHANGE RESINS

DRINKING WATER STANDARDS

HEALTH EFFECTS


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WHAT IS DRINKING WATER?

Drinking water is water that is safe

for humans to drink

to use for other domestic purposes, such ascooking, washing up, bathing and showering.

Drinking water is so important for goodhealth. Our body is estimated to be about 60to 70 percent water. Our body needs water toregulate body temperature and to provide themeans for nutrients to travel to all organs.

Water also transports oxygen to cells,removes waste, and protects joints and organs.


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WHERE DOES DRINKING WATER

COME FROM?


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Water Types

Surface waterAll water, fresh and salt, that is direct contact

with the atmosphere. Oceans, rivers and lakes

are all sources of surface water.

GroundwaterWater found below the Earths surface in

geological reservoirs known as aquifers.

Groundwater flows out of the ground naturallyin springs and seeps, and can also be pumped outby wells.


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Types of impurities in water are:

Arsenic

Bacteria

LeadNitrate

Organic Pollution

Tastes and odours

Hardness

Disinfectants

DRINKING WATER CONTAMINANTS


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Drinking water contaminants which aretreated by ionexchange

Contaminant Possible cause ofproblem

Solutions

Arsenic Naturally occurring in waterin some areas

Reverse osmosis; ionexchange

Nitrate Well not sealed; faulty

septic system; animal waste;fertilizers

Remove source of

nitrate; distillation;reverse osmosis; anionexchange

Bad odor, color,taste

Variety of sources Ion exchange;activated carbon filter;

chlorinationHardness Naturally occurring minerals

in water

Ion exchange

Disinfectants Water additive used tocontrol microbes

Ion exchange


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CategorizingHardness

Worded Description Sanitary Engineers(mg/Las CaCO3)

Water ConditioningIndustry (mg/Las

CaCO3)

soft water 0-75 0-50

somewhat hard water 76 to 150 51-100

hard water 151 to 300 101-150

very hard water 301 and up 151 and up


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DRINKING WATER TREATMENT

FLOCCULATION/SEDIMENTATION

FILTRATION

ION EXCHANGE

ADSORPTION

DISINFECTION

(CHLORINATION)


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WHAT IS ION EXCHANGE?

Ion exchange is a technology used for the treatment ofgroundwater, surface water and leachate.

The ion exchange process consists of at least three steps:

Adsorption or loading: Contaminated water is pumpedthrough the system where exchange takes place.

Regeneration: A regenerant solution is used to displacethe contaminant ions that are adsorbed on the exchangeresin.

Rinse: To extend the life of the exchange resin and toensure proper flow characteristics before the next

adsorption cycle.


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The two widely used applications of ion exchange:

1) The removal of hardness ions (softening) fromdomestic and industrial watersGroundwater dissolves rocks and minerals releasing

calcium and magnesium ions that cause water to be hard.These dissolved ions give hard water its characteristics.

2) Complete demineralization of waters for industrialpurposes

In its more general form, IE for both + and - can alsobe called deionization. Deionization is used for medical andindustrial situations requiring very pure water.Deionization is not necessarily for drinking watertreatment, and would produce very flat tasting water.


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Types of ion exchange process:


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Water Softening


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Ion x ange (Water oftener)

Treats hard water (calcium and magnesium)

Removes barium, radium, dissolved iron, manganese

Removes some bad odors, colors and tastes

Anion exchange unit can remove nitrate, fluoride

Advantages Disadvantages

cleaner, softer feelingclothes

Softened water is not recommendedfor watering house plants and gardensdue to its sodium content

longer life of appliancesincluding washing machine,

dishwasher, and water heater

reduce the effectiveness of smallseptic or sewer systems

less use of householdcleaning products, such as

detergents

there may be health risks fromsodium intake

reduction of water spotting softened water is not recommended

for steam irons or evaporative coolers


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Water Deionizers

use both Cation and Anion Exchange to exchange both positiveand negative ions with H+ or OH- ions respectively, leading tocompletely demineralized water.

Deionizers do not remove uncharged compounds from water, andare often used in the final purification stages of producingcompletely pure water for medical, research, and industrialneeds.


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Deionization

Advantages Disadvantages

Removes dissolved

inorganics effectively

Does not effectively

remove particles, pyrogensor bacteria.

Regenerable (servicedeionization)

DI beds can generate resinparticles and culturebacteria

Relatively inexpensiveinitial capital investment

High operating costs overlong-term


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ION EXCHANGE RESIN

An ion-exchange resin or ion-exchange polymer is aninsoluble matrix normally in the form of small (1-2mm diameter) beads, usually white or yellowish,fabricated from an organic polymer substrate.


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Resin Types

o Ion exchange resins are classified as cationexchangers, which have positively charged mobile ionsavailable for exchange, and anion exchangers, whoseexchangeable ions are negatively charged. Both anion

and cation resins are produced from the same basicorganic polymers.

Cation-ExchangersoStrong acid

oWeak acidAnion-ExchangersoStrong BaseoWeak Base


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Strong Acid Exchangers

Can convert neutral salts into their corresponding acids

NaCl + R-H HCl + R-Na

Weak Acid Exchangers

Posses carboxylic acid groups as the functional species

Strong Base Exchangers

Are less stable than strong acid resins

R--NH3OH+ HCl -> R-NH3Cl + HOH

Weak Base Exchangers

Behave much like their weak acid counterparts

Can be regenerated with NaOH, NH4OH or Na2CO3


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DRINKING WATER STANDARDS

TurkishTurkishStandards TSEStandards TSE

World HealthWorld HealthOrganizationOrganization

USA environmentUSA environmentprotection(EPA)protection(EPA)

Arsenic(mg/l)Arsenic(mg/l) 0.050.05 0.010.01 0.050.05

Fluoride(mg/l)Fluoride(mg/l) 1.51.5 1.51.5 0.70.7--2.42.4

Mercury(mg/l)Mercury(mg/l) 00 00 00

Nitrate(mg/l)Nitrate(mg/l) 5050 5050 4545

Chloride(mg/l)Chloride(mg/l) 600600 250250 250250

Color(Degree)(mg/l)Color(Degree)(mg/l) 2020 1515 1515

Smell value(mg/l)Smell value(mg/l) 33


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TurkishTurkish

Standards TSEStandards TSE

World HealthWorld Health

OrganizationOrganization

USA environmentUSA environment

protection(EPA)protection(EPA)

pH(mg/l)pH(mg/l) 6.56.5--9.29.2 6.56.5--8.88.8 6.56.5--8.58.5

Copper(mg/l)Copper(mg/l) 33 11

Detergents(mg/l)Detergents(mg/l) 0.20.2 0.50.5

Sulphate(mg/l)Sulphate(mg/l) 250250 250250 250250

Calcium(mg/l)Calcium(mg/l) 200200

Hardness,Hardness,

CaCOCaCO33(mg/l)(mg/l)

500500

Magnesium(mg/l)Magnesium(mg/l) 5050

Potassium(mg/l)Potassium(mg/l) 1212

Sodium(mg/l)Sodium(mg/l) 175175 200200


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HEALTH EFFECTSMicroorganisms:

Viruses (Gastrointestinal illness)Disinfection Byproducts:Bromate (increases risk of cancer)Chlorite (Anemia; infants&young children, nervous system effects)Disinfectants:Chlorine (Eye/nose irritatition; stomach discomfort, cancer)

Inorganic Chemicals:Copper (liver and kidney damage)Cadmium (kidney effects)Arsenic (risk of cancer and skin damage)Fluoride (bone disease)

Nitrate (Shortness of breath and Blue Baby syndrome)Organic Chemicals:Dioxin (Reproductive difficulties; increase risk of cancer )Toluene (Nervous system, kidney or liver problems)RadionuclidesUranium (increases risk of cancer, kidney toxicity)


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I HAVE TALKED ABOUT

DRINKING WATERDRINKING WATER

ION EXCHANGEION EXCHANGE

DRINKING WATER STANDARDSDRINKING WATER STANDARDS

HEALTH EFFECTSHEALTH EFFECTS


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ion exchange in water treatment-drinking water production