Removal of organic micropollutants by coagulation and adsorption

The Science of the Total Environment, Elsevier

Science

REMOVAL

V.

L.

Publishers

OF ORGANIC

SNOEYINK

Department Urbana,

A.S.C.

Civil

Illinois

47 (1985)

155-167 - Printed in The Netherlands

Amsterdam

MICROPOLLUTANTS

and

of

B.V.,

BY COAGULATION

155

AND ADSORPTION

CHEN

Engineering,

University

of

Illinois,

208

North

Romine,

61801

ABSTRACT The factors which affect removal of organic micropollutants by coagulation, sedimentation, filtration and activated carbon adsorption will be reviewed. Removal of soecific comoounds bv coaqulation, sedimentation and filtration is often slight; unless the pollutants adsorb on particles or associate with humic substances which are then coagulated. By comparison, removal of humic substances by these processes can be substantial, depending upon the water chemistry and the process conditions. Activated carbon may be applied in both the powdered (PAC) and granular (GAC) form. PAC and GAC have been used successfully throughout the world to remove odorous compounds. PAC has been used to a much smaller extent for removal of other micropollutants, but there is much potential for improvement of the application procedure so that good GAC is widely used to remove micropollutants other results can be achieved. than odor in Europe but has not been extensively used for this purpose in North America. The compounds which can be removed by GAC are presented and process monitoring procedures are discussed. Factors which limit its use include incomplete knowledge about which compounds must be removed and what effluent concentrations are acceptable.

INTRODUCTION Humic

substances

along

stitute

the

bulk

stances

are

naturally

and

terrestrial by

organic

compounds

and

themselves,

metals

water as

from

supplies,

pollutants

that

are,

also

often levels.

in

general,

0048-9697/85/$03.30

at

can

trace

or

0 1985

the

and

carcinogenic these removed

Elsevier

through

pollutants

such water.

a variety

may

be

are

harmful usually water

B.V.

for

as The

of

ways sources

These even small treatment

pesticides organic

their

runoff.

by conventional

Publishers

halogenated required

find

sub-

aquatic

health

other

materials

activities,

and

Science

and

the

little

levels

agricultural

Humic in

of

finished

man's

con-

waters.

activity

although

toxic

into

micropollutants

natural

(THMs)

quantities,

Further, poorly

of

concentration

transport

from

organic

biological

substances,

discharges toxic

pool

of

environment

in

of

trihalomethanes

primarily

industrial

are

concentration

form

the

usually and

(TOC)

chlorination

derived

domestic

carbon products

can

They

micropollutants,

quantities

These

during

disinfection. heavy

organic

trace

occurring

environments.

concern

water

total

with

at

to such

organic very

molecules processes.

low

156

The

growing

pounds

in

concern

drinking

prompted

many

tional

studies

water

hazardous role filtration and

treatment

the

and

COAGULATION, of

Naturally alum

NORS

survey

in

or

an

that

TABLE

Table

treatment

was

fractions

showed

that but

to

natural

organic

reported

removals

of

Water Type of

be

humic

be

The

the

substances

factors

that

discussed.

removed

effectively and

removal

there

good been

was

of no

removal,

by

attempt

were up

are

The

to

reported,

to

90%

laboratory

coagulation

coagulation

TOC averaged

apparent

and in

by filtration.

nonvolatile

(40-60%)

observed

removal

Source/ Organics

organic

Test Treatment studies, sed/filt

EPA - Ohio

Pilot studies, sed/filt,

Rhine Alpine

River, lakes

Humic

acids

River

constituents

30%

optimize

the

presumably

removal

of The

tests. summarized

as

selected factors follows:

Lab

are

from

% Removals -30

TOC

60

DOC

25-40

9 III)

tests,

60-90 and

tests,

Al(II1) Fe(II1) These data

coagulation.

/

pH > 7

Al(II1) Fe( III) Acids

by

NVTOC

plant coa Al

water

Constituents

plant coag/

Al(III),

Lab

in

Conditions

National Organics Reconnaissance Survey (63 plants)

NOTE:

of

sedimentation

water

get has

behavior treatment.

will

review

sedimentation,

1

Summary

Fulvic

can

fromriver

made

the

healthwe

matter

subsequent

plants,

organic

water

organic

matter and

removals

coagulation,

and

paper,

conven-

FILTRATION

AND

1)

attempt

affect

from

occurrring

salts

including on

comhas

of

toxic

In this

water

organic

effectiveness

potentially

drinking

compounds

the

of

significance

supplies.

adsorption,

organic

ferric

Higher

natural

these

types health

on

removing

water

during

naturally

(see

63 water

removal. when

carbon

occuring

with

in

different public

decade

processes,

SEDIMENTATION

Coagulation

its

past

from

activated

of

of

and

processes pollutants

micropollutants

removal

presence

the

physico-chemical

organic

affect

the

supplies during

organic

of

over

water

a literature

lo-60 and

review

by

Kavanaugh

(1978).

157

(1)

pH.

The

removal

pH is

5-6

for

alum

values

of

pH,

anionic

salts

by (2)

the

concentration more

of

(3)

Coagulant

substances floe,

but

humics

may

by

bonds

salts

Both

and

needed

on

polymers

with

alum

alum

However,

the

polymer

et

simple

water

direct

give

and

be

al.,

(Amy

not

added

after

to

decreasingpH, with

effective

be

and

in

the

for

removal

1984).

high

to

a settleable

suitable

weight

substances

bridge

of

Further

molecular

humic

alum

humic

form

Chadik, of

for

the

with interact

readily

use

results

proportional

1978).

may

The

these

coagulant

reactions.

not

are

thus

however.

satisfactory

should

do

salts

filtration

topic,

decreases

and

do

floe

of

usually

and

optimum At

cations

is

et

ferric

the

1978).

neutralizing

required

(Semmens and

water; al.,

polymeric

polyelectrolytes

this

does

acidic

(Semmens

protonated

a filterable

coagulation is

by

in

coagulant

produce

or

dose

become

slightly

with

substances

Cationic

research

interact

groups

type.

removal.

salts

coagulant

humic

of

from

ferric can

The

of

cations

better

for

chemical

dose.

carboxylic

polymeric

much

4-5 humates

formation

Coagulant

since

is

and

removal.

destabilized

floe

particles. (4) to

Preozonation.

increase

cursors it

by

works

removal

coagulants.

dose

produced A study

of

ozone

on

the

in

detail,

of

of

treatment co-workers

(1982)

of

humic

several

direct

effect

humic

is

by

example,

humic

removed. substances

to

and

Liao

of

by

(1984) and

this

effect

suggests

removed

that

by aluminum

(Elefritz

et with

a very

of

preozonation

The

effect

coagulation

fulvic al.,

the

has

al.,

not

also

adsorb

Favorable

conditions

onto

pH (>ll.O),

or

and

1984)

also slight

been

removal

aggregates,

or

the

at

effective

this

carbonate adsorption a high

calcium

also

studied

can

THM precursors

water

process.

reported

calcium for

process

acid

1977)

softening

calcium-humate

high

although

potential

softening

attributed

substances

include

lime-soda

et

1960)

substances

why

pre-

but

small.

40-50%

(Singley

(Wilson,

lime. by

show

ozonation

easily

reported THM

1983),

to

after

Florida

with

al.,

needed

be more

in

been and

softening by

up

et

THM formation

probably

substances

precipitation which

can

micropollutants

groundwater

plant

is

has

compounds,

precursors

supplies

substances

For from

research THM

of

coagulation organic

(Saunier

by coagulation

humic

substantial. removed

then

water

organic

the

humic

Removal

in

of

before

salts

ozonation

reduction

of

but

of

by

followed

removal

Removal

further

removal

a significant

water particles,

aluminum

waters,

increased

compounds

of

color,

with

certain

The

reported

of

coagulation

in

occurs. polar

Ozonation

the

were

an

English

Randtke

and

removal

(up

to

be

mechanisms

through solid and

water

40-80%) involving

coprecipitation, surfaces

and

coprecipitation but

a low

are of

carbonate

158

concentration

in

phosphate

and

Coagulation

of

Specific

specific

organic

They

may

in

water.

material of

the

humic

The

degree

the

characteristics

quality

of

onto

the

floe

et which

precipitated

with

Very

few

processes by

of

(1976)

from

distilled O-30%

removal

pH,

were and

of

Pesticides

a few

indicated

parts

in

parathion

or

2,4-D,

Removal

of

specific

Lime-sode water.

monomeric not

removed

3,

water

sea

they

water directly

may

be

water

of

water

molecules

or

and

or

and

factors

the

quality

of

ferric

(DHBA)

and

most

of

the

Semmens

specific

sulfate

and

water)

was

Both

removal

studies,

lake

effect.

the

concerning

these

removal ions,

important

treatment

reports

most

The

by alum

the

adsorb

A few In

ferric

acid

be

at

parts

molecules, softening

does and except

and

compounds and

resorcinol,

or

billion

found and

no

level.

any

and containing

significant

the

remove co-workers

ferric

specific (1982)

The

the process

essentially

no

salts.

organic reported

phosphoryl/phosphonyl extent.

by at

lindane, is

or

98%

coagulation

dieldrin,

alum

process.

followed

up to

There

by softening

effectively

coagulation salts,

comparison,

compounds

Randtke

the

ferric

endrin,

by either

not

by

methoxychlor

toxaphene

those to

By aldrin,

per

alum

DDT and

level. removing

organic

(1984)

removed

with

removed

in

softening

effectively

coagulation

rotenone,

Liao

by

an

concentration

2,4,5-T

of

organic

have

compounds,

and

conventional

2.

investigated

filtration,

effective

removal

from

can

Table

billion less

the

organic

also

coagula-

filtration.

by coagulation

and

per much

of

with

to

by

removed.

(e.g.,

of

on

and

the

or

then

determined.

dihydroxybenzoic

pesticides

sedimentation

be

water

suspension may

by

adsorb

acid.

removal

Only

of

in

Table

complex

deionized

vanillic

nature

role

in

not

(1975)

of

and

coagulation or

from

addition,

the

by

removed

micropollutants.

very

nature

and/or removal

the

coprecipitation

Albert

magnesium

sedimentation,

and

summarized

considered

water

compounds

on

organic

could to

solution

done

were

removal

attributed

only

is

of are

examined

Ocanas

on

Organic

been

be

materials

ions

mechanism

studied

depend

coagulant

solutions

including

can

from

removal

as

solids.

substances

particles,

colloidal 1978).

have

from humic

then the

metal

the

water

removed

results

the

As

will

coagulation

frequently

They

the

such

carbonate

with

coagulant

studies

onthe

removal

be

and

al.,

calcium

associate

association

(Semnens

some,inorganics

of

may

substances

of

of

compounds

compounds

means.

colloidal

presence

crystallinity

organic

different

tion

water,

poor

compounds that groups,

softening

process,

simple are

159 TABLE

2

Removal

of

specific

organic

compounds

Concentration Level

Compound phenol citric acid citric acid resorcinol vanillic acid DHBA* glucose glycine glycine phenylalanine glutamic acid aspartic acid succinic acid glycollate lysine

Coagulant Used

10 125

!lg/L u9/L 0.1-1.0 mg/L 2-10 mg/L 10 mg/L 2-10 mg/L 0.1-l mg/L 0.1-l mg/L 8 v9/L 0.1-l 0.1-l 0.1-l 0.1-l 0.1-l

by coagulation.

mg/L mg/L mg/L mg/L mg/L

% Removal

FeCls FeCls FeCls/NaOH Fez(SOt,)s Alum b(Sh+) 3 FeCls/NaOH CuC12/NaOH FeCls Fe(OH)s FeCls/NaOH FeCls/NaOH FeCls/NaOH FeCls/NaOH FeCla/NaOH

Source Water

60-87 20-30 90 O-8

Lake Lake Sea DDW' DDW DDW Sea Sea Lake Sea Sea Sea Sea Sea Sea

If30 16 48 25-50 53 90 77 60 45 73

of Reference

water water water

water water water water water water water water water

Sridharan Sridharan Chapman Semmens Albert Semnens Chapman Chapman Sridharan Tatsumoto Chapman Chapman Chapman Chapman Chapman

& Lee & Lee & Rae & Ocanas & Ocanas & Rae & Rae & Lee et al. & Rae & Rae & Rae & Rae & Rae

1

DDW-distilled-deionized *DHBA-dihydroxybenzoic

TABLE

water acid

3

Removal

of

pesticides

by

coagulation.

Concentration Level

Pesticide DDT

Coagulant Used

0.1-10

mg/L

Alum,

Fe2(S0,)s, FeCl,

or DDT DDT methoxychlor

lo-25

ug/L

l-10

mg/L

lindane dieldrin endrin 2,4,5-T parathion aldrin 2,4-D

l-10 l-10 l-10 l-10 l-10

)Jg/L ug/L pg/L ug/L ug/L

rotenone toxaphene toxaphene

cl70 <400 <400

however,

is

containing of

polymerization.

effective

pg/L ug/L pg/L

in

functional The

Alum Alum Alum or Fe2(%)3 Alum Alum Alum Alum Alum Alum Alum or b(SOt,)a Alum Alum Alum

removing

groups. removal

% Removal

is

removal also

40-80

Carol10

98 30-40 55-95

Robeck et al. Whitehouse Steiner & Singley


Robeck et Robeck et Robeck et Robeck et Robeck et Whitehouse Aly & Faust

26;

10 o-3 0

polymeric The

electrolytes increases affected

Reference

Cohen et Cohen et Nicholson

possessing with

increasing

by other

molecular

al. al. al. al. al.

al. al. et

oxygendegree

al.

160 characteristics

including

molecular

degree

of

removal

of

volatile

acids

(Randtke

1977),

and

other

purgeable

halogenated

1979)

have

been

occasionally

reported,

the

removal

incorporation drawn

about

of

these

into

the

softening

efficiency

of

the

ACTIVATED

CARBON

Activated

carbon

form.

PAC is varied

the

was

organic

compounds.

The

to

of

compounds

is

benefits replacement

The

of

for

which

compounds different (1980)

al.,

studies

atmosphere

or

can

be

unknown.

Thus,

unknown

contamination

will

have

GAC to

to

be

Cohen

a broad in

(1980)

different adsorption

show'some

set

use remove

surface

need

in

America.

The

major

puri-

for

removal

and

the

been con-

the

possible

benefit

organic

health

The

frequency

of

of

harmful

concentrations is

parameters

to

be and

that

compounds

long-term

unknown. high

not

the the

the

problem

consider

of

volatile

improved

has

quantifying

majority

GAC other

Europetoremove it

who

of

water

for

processes used

adsorption

the to

can

used,

its

health

regeneration

or

arbitrarily.

compounds remove

of

our

(GAC) dose

and

although

largely

its

with

odor

is

design

reported

and

of the

periodic if

and

used

tetrachloroethylene,

identified are

and

and

many

process. granular

for

also

officials

cause

odor

supply

treatment

found

and

reason is

widely

The

might

and

now

and

North

been

been

(PAC)

taste

been

regulatory

not

have

extensively

organic

in

water

organic of

been

the conclusions

GAC adsorption

taste

expenditure.

be largely

specific

of

GAC has

and

have

largely

128

exhibit

but

use

purpose

the

spills

Dobbs

Suffet

predominant

odor,

than

surface

that

example,

that

this

for

For

and

fact,

other

waters

ability has

The

the

In

frequency

Removal

of

groundwater

including

for

will

to no

et Oemarco,

these

treatment

trichloroethylene

managers

of

in

water

of

those

occurrence

loss

powdered

highlighted

be obtained

effects

apparent

drinking

the

have

surface

not

compounds.

control

and

of as

compounds.

in

and

these

vulnerability

utility

that

(Singley

(Hood

removing

the

adsorption

would

water

taste

used

of

both

for demands.

such

a common in

control

micropollutants

fronting

in

of

extensively

THMs

of

contamination

procedures,

1982),

Therefore,

organic

fication

use

and

compounds is

recognition or

organic

is

occurrence

supplies

organic

it

a result

softening

primarily

compounds,

increasing

al.,

but was

problem

widespread

organic

et organic

sludge.

be applied

added

as

compounds

adsorption may

initially

of

charge,

ADSORPTION

carbon

Activated

be

molecular

geometry.

The

if

hydrophilicity,

are

spectrum the

of

literature

reported

sizes,

characteristics. adsorbed,

compounds

during

single-solute

structures,

strongly

organic

the

from

last

isotherm functionalities, Data

whereas

compiled others

20 years data

for etc.,

by McGuire are

weakly

161 adsorbed

(see

surface

and

ated

Figure

compounds,

organic

and

been

compounds

to

most

or

been

THMs,

(PAH),

toxic of

efficiency,

95%

have

e.g.,

be

of

removal

exceeds

that

hydrocarbons

shown

removal the

often

the

concentrations,

aromatic

have Effective

pesticides,

of

low

polynuclear

GAC treatment,

and

Many at

pesticides,

concentrations. by

1).

groundwaters

in halogen-

nitrosamines

and

or

carcinogenic

these

compounds

can

for

PAH,

nitrosamines

Aly

(1983)

for

especially

more

detected

volatile

(see

Faust

and

at

higher be

achieved

a

review).

Fig. 1980).

1.

General

Removal

of

The

amend

volatile

discovery

of

THMs

resulting

matter,

e.g.,

the

National

maximum

contaminant removal

both

pure

from

most

life

or

weeks, and

of time

than the

adsorption

other

quently, in

specific

and

organic

THMs

and

review

humic

level

(MCL) compounds

to

and

pilot-

pilotand

breakthrough

that

of by

normal Faust

compounds

of

in

0.1

for

mg/L

by and

the

Aly

THMs for

(1983).

total

THMs

is taste

Therefore,

to

include

that

odor the

ranging control use

the carbon from

(see of

a

extensively of

the

EPA to

Conse-

studied

shorter, and

the

Review

indicate much

Suffet,

occurring

led

(TTHMs).

was

studies.

studies

naturally has

Regulations

GAC adsorption

full-scale

and

(VOCs)

supplies

Water

operation and

McGuire

of

water

Drinking

full-scale of

(after

fromthechlorination

Primary

these

systems the

organic

substances,

Interim

of

isotherms

GAC for

data bed4-26 Figure THMs

2

162

0

1

2

TIME

Fig. 1981).

2.

Removal

removal and

other

alternatives highly

often

volatile of

discharged

Removal

the

adsorptive

generally

low

compounds

(see

initially

and

Figure

of

Since

Snoeyink the

al.,

exhausted

can

than

not

air

in

carbon,

AWWA Research

advantage be

from be

over

removed

effluent

may

THM

coagulation,

should

load

As Aly

stripping

ultimately

stripping in

if

air

and

air

permitted

stripping

the possible

humic on

indicated

(1983)

no

a rapid

state continues

is

some

gas

locations.

stream

cleanup

precursors

will

and

to

and

GAC

is

column.

filtration

for

cost

GAC bed-life of

of

treatment.

full-scale virgin

it

constant

Figure

3), of

sites

with

is

desirable

organics can

GAC is

operating

adsorption

adsorption process,

humic

a rather

(see

rate

expensive

The the

for

which

is

the

a short

removed

slow

compete an and

reduce

the

of

by

after

during be

and

removal

occurs

to

THM precursors,

nature

pilotthe

develops

activity

and

several

breakthrough

material

or

source

a review),

A steady

carbon

substances,

the by

for

sedimentation to

be

GAC for

biological

molecules,

the it

3).

precursor

micropollutant

reduce

but

because

optimize

this

depending

adsorbed.

of

molecules.

of

variable,

Faust

(see

percentage perhaps

gaseous

use

the

et

stripping.

effective

period

to

capacity and

being

studies

and

costly

(see has

compounds The

of

Symons

economical.

It

nonvolatile

(after

THM precursors

The

and

air

more

tapwater

regeneration

a review).

atmosphere

more

for of

for

or

VOC removal

incineration.

GAC is

required

are for

and

by to

However,

replacement

Report

both

Ohio

Cincinnati,

effective

Foundation-KIWA

is

THM from

frequent

GAC is

disposed

*

m(r

of

requires

that

3

IN OPERATION.

removal thus

be

large other to to

extended

163

Representative

TOC breakthrough

curves

(after

RobertsandSummers,

:2;,"*

Factors

affecting

Quality

GAC adsorption

of

GAC.

Specific

principal

characteristics

constitute

a major

molecular pores

but

pores

with

certain other

less

than

of

capacity

of

weight less

than

molecular

the

adsorptive

400

of

Traube's

rule).

in

organic

in

solubility

Factors

adsorptive

example, the

as

molecule

related molecule capacity.

the to

the

chain is

due

solubility and

an

substitution

of

adsorption

of

of

decrease

the

length polarity,

is

molecule

(or such

the

organic

ring

molecular as

affecting

molecules

from

(known

aliphatic

as acids

The

and weight)

functionality

structure,

acid

weight

increases. polarity

a

fulvic

ascended of

with

with

properties

a series

in

peat

the

decrease increases. of

also

in

the

acid

pores

molecular

significant

series

in

al.,

with

fulvic

in

1981).

adsorption

to

and

peat

(Lee

homologous

the

and volume for

et

some volumes

well

GAC capacity

most

length

chain

acid

possess

pore

correlate

pore

the

Micropores

penetrate

example,

Solubility,

the

general, as

adsorption

humic

50,000

are

to

GAC. many

can

For

found

molecules.

In

For as

than

solutes

increases

GAC increases

adsorbate

more

and

molecules

are

of

area,

however, with

distribution

capacity

pores. were

1000;

size

surface

commercial

adsorbate

pore

adsorbate

correlated

capacity.

solutions

increase

of of

specific

70 i

than

i

and adsorptive

smaller

for

less

weight

aqueous

on

GAC

of

Characteristics polarity

the

from

excluded

a radius

and

of Thus

of

with

portion

dimensions.

a molecular

area the

are

adsorption

radius

surface affecting

affect

the the

164

Ji!!!.

The

aqueous

adsorption

systems

is

undissociated

and

undissociated

form

alkaline

pH values

capacity

is

and values

more to

in

natural

waters, of

overall

efficiency

found

in

and et

the

the

appears

a pollutant

so,

treatment than

becomes the

before thus

removal GAC should

the

competitive

effective

ozone,

chlorine

aqueous

systems

different duce

of

for

more

polar

TOC removal

the

or

on

the

For

when

of other

the

the

be If

are in

matter

result

may

of

GAC or

alter react

the with

adsorbable

a GAC contactor

GAC the

rather

in

the

be

alumina water

a more

organic

such

compounds

on

to

substances GAC but leads

as in

GAC performance

often

and

cost-

1985). chemicals,

humic

GAC

activated

(Snoeyink, pretreatment

less

by the

or

sedi-

supplies,

objective

resin

the

with

the

with

micropollutants,

micropollutant

can

affects

water

removed

organic

GAC;

problem.

often

the

occurs saturation

conjunction of

synthetic

can

desorption

this

content to

wilil

complete

prevent

column

adsorbing

that

that

in

the

saturaiiun

GAC adsorption

oxidative

ozone that

activity

will

natural

surface

example,

so

organic

with

near

of higher

1)

strongly

is

so

organic

permanganate,

carbon

a more

column

to

of

concentrations

concentrations

quality.

on

intermediates

GAC.

of

the

at

specific

amount

removal

Microbial by

of

and

the

evaluating

occur

only

material

pretreatment

dioxide,

solutes

Competitive

can

occur

organic

removal

or

pH

displacement

that

decreases

the

of

chlorine,

degrees.

biodegradable.

of

interactions

process

Reactions

reduce

water

reduce

At

decrease

possible.

possible

Coagulation

product

TOC,

pK,.

Since

when

adsorber

prior

the one of

is

the

treatment.

amount

to

a GAC filter

the

not

treatment

can

the

adsorptive pH decreases

single

widely,

highly

and

2)

of does

water

improving

as

compounds. vary

is

event

concentration

filtration

At

as

may

exist

considered

a pollutant

Operation

Water

reducing

of

and

concentration

and

and

with

influent

during

the

the

equal

not

many

it

This

influent,

GAC with

process.

influent.

the

be

the

carbon.

compounds

effluent

in

Pretreatments.

thereby

the

acid,

capacity

can

adsorption,

1984).

GAC performance

column

GAC

nearly

the

al.,

influent

mentation

the

competitive

or

of

from both

form.

increases

do

compounds

therefore

organic

GAC

on

ionized

numerically

the

by general,

adsorbed

the

adsorptive

of

adsorbed

in

pH is

as mixtures

should

pH.

In

be

than

pollutants

organic

appear

saturated,

(Thacker

rather

can

a weak

the

value,

bases,

capacity

properties

strongly

the

may

compound

pKa

different

of

of

pollutants

at

but

of

where

Organic

adsorption

Because

are

the

adsorbate

pKa

and

solution

adsorptive

range

surface

by

on

is

than

adsorbed

effects

than

the

acids

adsorbed

the The

adsorption.

adsorbability weakly

than

in

an

strongly

reduced.

as

by the

of

more

greater

inthe

Competitive

forms

being

acidic

changes

affected

ionized

occurs

such

electrolytes,

generally

greatly

a maximum

due

of

to usually to

improved

promore

165 Current

research

at

chlorine-containing adsorbed

organic

compounds. formed

when

on

these

products

this

USA,

effect

are

to

be

the

desorb

Voudrias

reevaluated

al. to

and

when

to

GAC with

and

the

also

column.

obtained

Additional

Therefore,

where

water

adsorbed.

GAC adsorbers,

eliminated

of

drinking

was was

carbon

(1985).

a series in

mixture

the

are 2,4-

including

2,4-DCP

a

adsorbed

reactions

encountered

then

et

carbon

products

from

that,

applied

solution

product and

disinfectants

is

HOCl-GAC-adsorbed

unusual

HOC1

may by

the

A similar

with

given

with

normally

4).

chlorine-containing needs

give

indicates

NH2C1)

of

example,

will

Table

also or

both

concentrations

some

in

Reaction

(see

react

For

treated

of

TABLE

HOC1

Illinois C102

characteristics

present.

first

of

will not

GAC was

cation the

it

reaction

at

practice

Further, data

is

(DCP) PCBs

the

of (HOCl,

products

carbon

dichlorophenol

treatment

University

compounds,

Unusual

hydroxylated

when

the

disinfectant

as

the is

very

applicommon

possible.

4 products

from

HOCl-2,4-dichlorophenol-GAC

reactors

Reaction

Compound 0 (x=0-l)

I

(y = 2-3)

I of=31

Cl

(OH), 4 0 COOMe

1-m OH

(y=2)

(CI)y

I-E ,,,,&@,,l;z

I. 1:::

IV.

Preadsorbed 2,4-DCP Preadsorbed 2,4-DCP Preadsorbed 2,4-DCP peat fulvic acid. 2,4-DCP reacted with

z =3-4)

reacted reacted reacted

with with with

chlorine-preoxidized

10 mg/L HOC1 as C12. 1.5 mg/L HOC1 as C12. 1.5 mg/L HOC1 as Cl2 F-400

GAC.

in

the

presence

of

156 CONCLUSIONS Good

removal

sedimentation

of and

chlorinated

compounds

quantities

of

employed.

Specific

highly carbons,

which by

organic

when

organics

surface

removed

natural filtration.

which

active

compounds,

adsorb

to

is

must

be

such

by

in

the

by adsorption

DDT

the

not or

coagulation,

production and

generally as

in

achieved

post-chlorinated,

removed are

particles

excellent

removals

upon

the

constituents

compete

with

the

micropollutant

affects

thereplacement

formation

water

be results

if

GAC adsorbers

are

except

aromatic

These

fewer

reduced

well-removed,

polynuclear

water.

of

in

for

hydro-

particles

can

then

be

coagulation.

GAC gives

the

can

removal

micropollutants

depends

adsorption

the

matter This

is

also of

frequency important. many

compounds

of of

many the

for of

micropollutants, The

water. adsorption the

GAC.

Prechlorination, which

otherwise

but presence

sites

on

would

which

GAC significantly of

example, not

performance

substances

the

Pretreatment for

its

of

the can

be

water result

before in

present.

REFERENCES Influence of dissolved organic compounds on flocculation. Albert, G., 1975. Heft 9, Engler-Bunte Inst., University of Karlsruhe, FRG. Aly, 0. M. and Faust, S. D., 1965. Removal of 2,4-dichlorophenoxyacetic acid derivatives from natural waters. J. Amer. Water Works Assoc., 57: 221. Amy, 6. L. and Chadik, P. A., 1984. Cationic polyelectrolytes as primary coagulants for removing trihalomethane precursors. J. Amer. Water Works Assoc., 76: 527. AWWA Research Foundation-KIWA, 1983. Occurrence and removal of volatile organic chemicals from drinking water. Cooperative Research Report published by the AWWA Research Foundation, Denver, CO. Carolla, J. A., 1945. Removal of DOT from water supplies. J. Amer. Water Works Assoc., 37: 1310. Chapman, G. and Rae, A. C., 1967. Isolation of organic solutes from sea water by co-precipitation. Nature, 214: 627. Cohen, J. M., Kamphake, L. J., Lemke, A. E., Henderson, C. and Woodward, R. L., 1960. Effect of fish poisons on water supplies, Part I. Removal of toxic materials. J. Amer. Water Works Assoc., 52: 1551. Dobbs, R. A. and Cohen, J. M., 1980. Carbon adsorption isotherms for toxic organics. EPA-600/8-80-023, U.S.E.P.A., Cincinnati, OH. Elefritz, R. A., Porter, D. W., and Morris, S. F., 1984. The application of ozone in softening processes for cost-effective THM control: Two case histories. Presented at Seminar on Strategies for the Control of Trihalomethanes at the AWWA Southeast Annual Conference, Jekyll Island, GA. Faust, S. D. and Aly, 0. M., 1983. Chemistry of Water Treatment. Ann Arbor Science, Woburn, MA. Kavanaugh, M. C., 1978. Modified coagulation for improved removal of trihalomethane precursors. J. Amer. Water Works Assoc., 70: 613. Lee, M. C., Snoeyink, V. L., and Crittenden, J. C., 1981. Activated carbon adsorption of humic substances. J. Amer. Water Works Assoc., 73: 440-446. Liao, M. Y., 1984. Removing soluble organic contaminants from water supplies by softening. Ph.D. Thesis, University of Illinois, Urbana, IL.

167 McGuire, M. J. and Suffet, I. H., 1980. The calculated net adsorption energy concept. In: -I. H. Suffet and M. J. McGuire, eds., Activated‘Carbon Adsorption of Orqanics from the Aqueous Phase. Proc. of the 1978 ACS Svmo. in Miami Beach, FL, Ann Arbor Science Publishers, Inc., Ann Arbor, MI. Grizenda, A. R. and Teasley, J. I., 1966. Water pollution by Nicholson, H. P., insecticides, a six and one-half year study of a water shed. In Proc. Symp. on Agri. Waste Water. U.S.E.P.A., Atlanta, GA. Randtke, S. J., Thiel, C. E., Liao, M. Y. and Yamaya, C. N., 1982. Removing soluble organic contaminants by lime-softening. J. Amer. Water Works Assoc., 74: 192-202. Robeck, G. G., Dostal, K. A., Cohen, J. M. and Kreissl, J. F., 1965. Effectiveness of water treatment processes in pesticide removal. J. Amer. Water Works Assoc., 57: 181-200. Roberts, P. V. and Summers, R. S., 1982. Performance of granular activated carbon for total organic carbon removal. J. Amer. Water Works Assoc., 74: 113-118. Saunier. 6. M.. Selleck. R. E. and Trussell, R. R., 1983. Preozonation as a coagulant aid in drinking water treatment. J. Amer. Water Works Assoc., 75: 239. Semmens, M., Edzwald, J. K., Taylor, M., and Sanks, R., 1978. Drganics removal by coagulation - a review and research needs. Presented at the 98th Annual AWWA Conference, Atlantic City, NJ. Singley, J. E. et al., 1977. Minimizing trihalomethane formation in a softening plant. U.S.E.P.A., Water Supply Res. Div., Municipal Environ. Res. Lab., Cincinnati, OH. Snoeyink, V. L., 1985. Trends in water treatment technology: disinfection, oxidation and adsorption. Presented at Cambridoe Meetino on Environmental Technology Assessment, Cambridge, UK. Sridharan, N. and Lee, G. F., 1972. Coprecipitation of organic compounds from lake water by iron salts. Environ. Sci. and Technol., 6: 1031. Symons, J. M.etal., 1981. Treatment techniques for controlling trihalomethanes in drinking water. EPA-600/2-81-156, U.S.E.P.A., Cincinnati, OH. Tatsumoto, M., Williams, W. T., Prescott, J. M. and Hood, D. W., 1961. Amino acids in samples of surface sea water. J. Marine Res., 19: 89. Thacker, W. E., Crittenden, J. C. and Snoeyink, V. L., 1984. Modeling of adsorber performance: variable influent concentration and comparison of adsorbents. J. Water Poll. Cont. Fed., 56: 243. Voudrias, E. A., Larson, R. A. and Snoeyink, V. L., 1985. Effects of activated carbon on the reactions of free chlorine with phenols. Environ. Sci. and Technol., 19: 441. Whitehouse, J. D., 1967. A study of the removal of pesticides from water. Kentucky Water Resources Institute. Wilson, A. L., 1960. The removal of fulvic acids by water-treatment plants. J. Appl. Chem., 10: 377. Wood, P. R. and Demarco, J., 1979. Treatment of groundwater with granular activated carbon. J. Amer. Water Works Assoc., 71: 674.