REMOVAL OF ORGANIC POLLUTANTS FROM THERMAL WATER BY ADSORPTION-COAGULATION METHODS AND ADVANCED OXIDATION PROCESSES

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21 Φεβ 2014 (πριν από 3 χρόνια και 5 μήνες)

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REMOVAL OF ORGANIC POLLUTANTS FROM THERMAL WATER BY
ADSORPTION
-
COAGULATION METHODS AND ADVANCED OXIDATION
PROCESSES

I
mre

Á
BRAHÁM
b
, A
ndrás

D
OMBI
a
, K
risztina

G
AJDA
-
S
CHRANTZ
a
, M
arcell

M
ÁJER
b
,K
ároly

M
OGYORÓSI
a
*
,

E
mese

S
ZABÓ
a
,
K
risztina

V
AJDA
a
**
, G
ábor

V
ERÉB
a

a., University of Szeged, Faculty of Sciences and Informatics, Research Group of Environmental Chemistry
,
Dóm tér 7
. Szeged
,
H
-
6720, Hungary

b., UNICHEM Kft., Tanya 461, Kistelek, H
-
6760, Hungary
, unichem@unichem.hu

(*Corresponding author, e
-
mail: k.mogyorosi@chem.u
-
szeged.hu)

**vajdak@chem.u
-
szeged.hu

E
xperimental

conditions


-
model

thermal

water
:

membrane

filtered

water

with

added

CaCl
2
,

MgSO
4
,

KCl,

NaHCO
3
,


-
Jar

Test

(JLT
6

VELP)

equipment

-
model

contamination
:

Na
-
humate,


-
Coagulant

/

adsorbents
:

PAC

(BOPAC,

UNIPAC

W
2
:

Unichem

Kft
.
),

Al
2
O
3

(DD
6
,

CPN
:

BASF)
,

-

non
-
ionic

polielectrolyte

(PE)

UNIFLOC

M
20

(Unichem

Kft
.
),

-
volume
:

500

mL,

temperature
:

25

°
C
.


The

treatment

steps
:

-

Sodium

humate

was

dissolved

(
0
-
2
-
5
-
10
-
50
-
100

ppm)

in

the

model

thermal

water,

-

Bopac

(
40
,

80

ppm),

then

PE

were

added

under

vigorous

stirring

(
180

rpm)

for

1

min,


-

the

mixture

was

stirred

with

40

rpm

-
sedimentation

for

40

min,

-
centrifugation

of

the

supernatant,

-
s
pectrophotometric

investigations

(
300

nm)

by

an

Agilent

8453

spectrophotometer
.


Optimalization
:


1
.

Total

treatment

time
:

60
,

80
,

100
,

120
,

140

160

min,

adsorption

equilibrium

has

been

approached

within

2

hours

(c
SH,
0

=

100

ppm,

c
Bopac
=

80

ppm,

c
PE
=

5

ppm)



further

tests

have

been

made

with

120

min

total

treatment

time
.

Figure

1
.



2
.

PE

concentration

was

studied

in

the

range

of

0
-
5

ppm

(c
SH,
0

=

100

ppm,

c
Bopac

=

80

ppm)
.

The

rate

of

sedimentation

increased

by

increasing

PE

concentration
.

Figure

2
.

c
PE

=

3

ppm

was

the

optimal

concentration
.

Figure

3
.


Coagulation

tests

(PAC)
:


1
.
,Adsorption

isoterms

of

humate
:


40

ppm

Bopac

or

UNIPAC

W
2
,

3

ppm

PE,

0
-
2
-
5
-
10
-
50
-
100

ppm

sodium

humate
;

stirring

time
:

120

min
.



Figure

4

demonstrates

the

humate

adsorption

with

Bopac
.

It

is

more

efficient

t h a n

Un i p a c

W
20


2
.
,
Influence

of

PAC

concentration
:

PAC

concentration

investigated

(
40
-
80

ppm)
:

at

higher

concentration

of

Bopac

the

adsorption

of

humate

is

closer

to

100

%

even

at

high

concentrations,


see


Figure

5
.

and

6
.

Adsorbent

test

(
Al
2
O
3
)
:

The

BASF

Al
2
O
3

(CPN,

DD
6
;

a
S
BET

=

280
-
350

m
2
/g)

were

te
sted

by

using

the

following

conditions
:

0
-
2
-
5
-
10
-
50
-
100

ppm

sodium

humate,

then

Al
2
O
3


powders

were

added

while

stirring

with

180

rpm

for

1

min,

-

the

mixture

was

stirred

with

40

rpm

for

70

min,

-

PE

was

added

(
3

ppm),

-
sedimentation

for

40

min
;


-

centrifugation

of

the

supernatant,

-
s
pectrophotometric

investigations

(
300

nm)


Samples

are

shown

in

Figure

7
.

C
onclusions

-
It

was

concluded

from

adsorption

isoterms

of

humate

that

high

basicity

coagulant

is

much

more

efficient

than

the

Al
2
O
3

adsorbents
.

The

best

performing

coagulant

BOPAC

provided

88
-
100

%

of

removal

efficiency
.


-
Coagulants

investigated

could

provide

very

efficient,

economic

and

rapid

removal

of

humic

substances

from

thermal

water
.


-
Although

organic

substances

can

be

efficiently

oxidized

by

H
2
O
2
/UV

method,

the

coagulation
-
flocculation

process

also

efficient

and

more

cost

effective
.


A
cknowledgements

This

work

was

financialy

supported

by

IPA

Cross
-
border

Co
-
operation

Programme

(HU
-
SRB/
0901
/
121
/
116
)

and

NKFP

DA_

THERM

TECH_
08
_A
4
.

KM

thanks

to

OTKA

(PD
78378
)

and

Bolyai

János

foundation

for

support
.


I
ntroduction


Various

types

of

natural

organic

matters

are

present

in

Hungarian

water

sources

(both

ground

and

thermal

ones)
.

A l t h o u g h

ma n y

of

these

organics

are

non
-
toxic,

but

some

of

them

are

potentially

hazardous

or

even

toxic,

such

as

aromatic

compounds
.

Used

thermal

water

could

be

released

into

surface

water

environmentally

friendly

only

after

the

removal

of

phenol

and

its

derivatives
.


Our

preliminary

experiments

indicated

that

phenol

cannot

be

removed

easily

from

water

by

traditional

adsorption
-
coagulation

methods
.

Therefore

Advanced

Oxidation

Processes

(AOPs)

could

be

applied

for

the

mineralization

of

aromatic

compounds
.




The

aim

of

our

present

studies

is

to

develop

an

effective

method

to

eliminate

the

inert

humic

substances

from

thermal

water

in

order

to

make

oxidation

technologies

more

economic

for

the

mineralization

of

aromatics

with

significant

toxicity
.

The

removal

of

sodium

humate

was

investigated

by

the

combination

of

coagulation
-
adsorption

methods

using

polyaluminum

chloride

(PAC)

coagulants

and

aluminum

oxide

adsorbents

in

model

thermal

water
.

The

concentration

of

sodium

humate

in

the

solution

phase

was

determined

by

spectrophotometric

measurements
.

C
omparison between the adsorption
-
coagulation and UV/

H
2
O
2

oxidation methods




1
μ
M

Figure 1
. The influence of the total treatment time

on the removal of hum
ate


(60, 80, 100, 120, 140 and 160 min)

Figure 2.

Effect of the PE concentration (c
PE
= 0
-
5 ppm)

Figure

4
.

Humate

adsorption

isoterm


with

40

ppm

Bopac

and

UNIPAC

W
20

Figure 6.
Humate adsorption with 80 ppm Bopac

Figure 5
. Humate adsorption with 40 ppm Bopac

Figure
7
.

The adsorption test with Al
2
O
3

(CPN)

Figure 3
. Effect of the PE concentration

on the adsorbed amount of humate

(
c
SH,0

= 100 ppm)

Figure
8
. Adsorption isoterms with Al
2
O
3

adsorbents (DD6, CPN)


DD
6

Al
2
O
3

was

better

adsorbent

than

CPN

(see

Figure

8
),

but

the

test

results

show

that

the

PACs

adsorbed

much

larger

amount

of

humate,

than

the

high

specific

surface

area

Al
2
O
3

adsorbents
.

Therefore

the

Al
2
O
3

is

not

suitable

for

the

removal

of

Na
-
humate

since

its

pore

size

is

too

small

for

the

humate

anions
.

Semi

pilot

scale

reactor
:


Sodium humate (c
SH,0
= 4,6 ppm) solution
with and without added H
2
O
2

in tap water
(volume: 200 L) was irradiated by a low
-
pressure mercury vapor lamp, using high
purity quartz sleeve surrounding the light
source. The lamp produces ozone from the
air flow that has been also applied in the
reactor, see
Figure 1
0
.

The influence of hydrogen peroxide, air
and oxygen purging was compared in
Figure 1
1
.


0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.00
2.00
4.00
6.00
8.00
10.00
12.00
Equilibrium concentration (mg/L)
Adsorbed amount (mg/mg Al2O3)
DD6
CPN
Figure
9
.

COD values after UV/
H
2
O
2


treatment at different irradiation times.

Remaining COD after coagulation
-
flocculation

is also shown

Figure 1
0
.

Semi pilot scale reactor

Figure 1
1
.

Absorbance changes during
irradiation with and without H
2
O
2

Conditions:


Oxidation of humic substances
and other natu
r
al organic
pollutants in groundwater (3 L)
was tested by UV/
H
2
O
2

(c
H2O2
=
100 ppm)

and
compared with
coagulation
-
flocculation method
(COD values were monitored,

Figure
9
).

0.00
0.02
0.04
0.06
0.08
0.10
0
60
120
180
240
300
360
Irradiation time (min)
Absorbance (300 nm)
Without hydrogen peroxide
100 ppm hydrogen peroxide with air
100 ppm hydrogen peroxide with oxygen
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0
10
20
30
40
50
60
70
Equilibrium concentration of Na-humate (mg/L)
Adsorbed amount (mg/mg adsorbent)
bopac
unipac
1.05
1.10
1.15
0
1
2
3
4
5
6
Flocculant concentration (mg/L)
Adsorbed amount (mg/mg Bopac)
9.3
21.1
20.6
20.6
22.6
16.4
15.8
4.2
0
5
10
15
20
25
0 without
H2O2
0 with H2O2
30
60
120
180
240
40 ppm
Bopac+1ppm
PE
COD