photo-fenton and photo catalytic oxidation process for ...

ISSN: 2347-7490 International Journal of Advanced Research and Technology (2015), Volume 3, Issue 1, pp.37-47 Journal homepage: http://www.ijartjournal.com RESEARCH ARTICLE

PHOTO-FENTON AND PHOTO CATALYTIC OXIDATION PROCESS FOR PRETREATMENT OF HIGH COD EFFLUENT OF AN API INDUSTRY AT PLANT SCALE Amit Kumar Tiwari1 Hemant Kumar Sharma2 D.N.Pandya3 1

2

Head EHS Depart ment, Sy mb iotec Pharmalab Pvt. Ltd. Superintending Engineer, MP Pollution Control Board (SEZ Pithampur), Indore, Madhya Pradesh 3 AVP Tech. (Site Head), Sy mbiotec Pharmalab Pvt. Ltd. SEZ Pithampura Dhar, M.P.-India Email- er.ati wari@g mail.com

Manuscript

Abstract:

Info: Manuscript History:

Received: Feb 10, 2015 Final Accepted: April 28, 2015 Published Online: April Issue Key words: API, Advanced oxidation, High COD effluent, Photo-fenton, Photo-catalytic Oxidation

The treatment of high COD value containing effluent of active pharmaceutical ingredient (API) industries has been big global problem due to presence of higher organic load, poor biodegradability and bio-recalcitrant compounds. The present work is aimed at optimization of Photo Fenton and Photo catalytic oxidation process at large scale. The present work evaluates the pretreatment of high COD value containing effluent of 4000 liters to 8000 liters in batch process at industrial scale, to make it amenable for conventional treatment by coagulation-flocculation followed by Activated Sludge Process (Biological - Aerobic treatment). The operational control and process optimization was focused on pH requirement for operation, Chemical Oxygen Demand (COD) reduction, reaction time, hydrogen peroxide & ferrous sulphate (Fenton) dose, UV light, control of residual hydrogen peroxide interferences and point of introduction of titanium oxide for further reduction of COD. The experiments for treatment of segregated high COD value containing effluent stream were conducted at at industrial scale in M/S Symbiotec Pharmalab Ltd. which is an API industry manufacturing cartico- steroids and situated in special economic zone (SEZ ) at Pithampur district Dhar, M.P. Copy Right, IJART, All righ ts reserved.

1.0 INTRODUCTION

high COD load as well as installation,

1.1 Treatment of pharmaceutical bulk drug or

operational trouble and maintenance cost of

Active

(API)

treating the effluent by reverse osmosis (RO)

industry’s effluent to achieve the standards of

followed by multi- effect evaporator (MEE)

treated effluent is a global problem. Although

and (ATFD) treatment has been a big

various technologies are being used to get the

challenge for the API industries. The organic

desired standards of treated effluent, however

chemicals present in high COD stream of

troubles in treating it by conventional

API

treatment methods due to its

completely

Pharmaceutical Ingredient

effluent by

do

not

always

conventional

degrade biological 37

Tiwari, A. K., Sharma, H. K. & Pandya, D. N. (2015)

ISSN: 2347-7490 International Journal of Advanced Research and Technology (2015), Volume 3, Issue 1, pp.37-47 Journal homepage: http://www.ijartjournal.com

treatment

processes

the

1.3 Photo Fenton (UV + H2O2 & Ferrous

pretreatment of this stream. Therefore, Photo

sulphate) processes for generation of

Fenton (solution of ferrous sulphate and

Hydroxyl Radicals:

hydrogen peroxide with UV light.) and Photo

The formation of hydroxyl radicals (HO• ) by

catalytic oxidation

processes (UV light.

Fenton’s reagent ( solution of Ferrous sulfate

along with titanium oxide acting as photo

and Hydrogen Peroxide) in presence of UV

catalyst)

light

can

even

prove

to

after

be

effective

pretreatment options combined with

lime

can be understood with following

reaction:-

treatment, before subjecting the high COD effluent to Activated Sludge Process (aerobic – biological treatment).

Fe3+ + H2 O

( UV) ( UV)

H2 O2

( UV)

H2 O

1.2

The

pre-oxidation

of

high

COD

Fe2+ + HO• + H+ 2HO• H• + OH•

( wave length < 400 n m)

containing effluent stream by Photo Fenton and Photo catalytic oxidation process is very effective to prevent the shock loading on Activated Sludge treatment Process (ASP) and improve the biodegradability of effluent stream in ASP (Tekin, H, et al. 2005, Tiwari & Upadhyay 2013, Tiwari & Jagan 2013). The Photo Fenton and Photo catalytic oxidation process produces highly reactive hydroxyl radicals which reacts with organic compounds (measured as COD) present in effluent and oxidize them to reduce the COD

The fenton solution produces hydroxyl radicals which have a very high oxidizing potential. They react with COD causing compounds present in effluent and oxidize them into H2 O, CO 2 and other intermediate compound and salts. The oxidizing power of Fenton’s reagent is highly improved by introducing UV light. (Pignatello, 1992; Legrini et al., 1993; Ruppert et al., 1993, Dantas et.al., 2003). 1.4 Photo-catalytic Process (UV+ Titanium Dioxide):

(Dantas et.al., 2003, Fatta-Kassinos et al. 2011;

Klavarioti

et

al.

2009).

This

pretreatment reduces the COD load in the ASP and make the effluent amenable for aerobic biological treatment system i.e. ASP.

Due to UV light illumination, electron- hole pairs are formed in the Titanium dioxide semiconductor

photo-catalyst.

When

a

photon with energy equal to or greater than the materials band gap is absorbed by the semiconductor, an electron is excited from

38 Tiwari, A. K., Sharma, H. K. & Pandya, D. N. (2015)


the valence band (vb) to the conduction

Reactions in vale nce band (hvb+)

band (cb), generating a positive hole in the

TiO2 (h vb +) + H2 O TiO2 + H+ + . OH + TiO2 (h vb ) + 2H2 O TiO2 + 2H+ + H2 O2 + TiO2 (h vb ) + OH TiO2 + •OH + TiO2 (h vb ) + H2 O2 HO• + •OH (vb= valence band cb= conduction band ) (Banerjee et.al.2006)

valence band. Due to the generation of positive holes and electrons, oxidationreduction reactions take place at the surface of

semiconductors

(http://en.wikipedia.org/wiki/Photocatalysi s). Holes are positive charges, which when come in contact with water molecules, produce ·OH and H+ ions. Electrons react with dissolved oxygen to form superoxide

1.5 Oxidizable compound by Hydroxyl Radicals: The hydroxyl radicals produced either by Photo Fenton or Photo catalytic processes,

oxidizes

variety of complex

compound e.g. Acids, Alcohols, Aldehydes, Aromatics,

Amines,

Dyes,

Ethers

and

·−

ions (O2 ), which react with water molecules −

to produce hydroxide ions (OH ) and peroxide radicals (·OOH). Peroxide radicals −

combine with H+ ions to form ·OH and OH , −

and holes oxidize OH to ·OH. Thus, all eventually facilitate the formation of ·OH, and these radicals attack the pollutants

ketones (Bigda 1995). The hydroxyl radical (HO•) can attack organic molecules found in highly polluted effluents by radical addition, hydrogen abstraction, electron transfer, and radical combination. Radical addition: R + HO• → ROH where R = reacting organic compound

present in the aqueous solution (Lazar Electron transfer: Results in the formation

et.al.2012). TiO2 + hv (UV)

TiO2 (ecb – + hvb +)

Reactions in conduction band ecb– TiO2 (ecb – ) + O2 TiO2 + • O2 − – • − + TiO2 (ecb ) + O2 + 2H TiO2 + H2 O2 TiO2 (ecb – ) + H2 O2 TiO2 + H- + . OH • . O2 − + H2 O2 OH + OH- + O2 • − + O2 + H HO•2 – • TiO2 (ecb ) + HO 2 TiO2 + HO-2 + HO 2 + H H2 O2 2HO•2 O2 + H2 O2

of ions of a higher valence R n + HO• → Rn-1 + OHHydrogen Abstraction: R + HO• → R. + H2O Radical Combination: HO• + HO• → H2O2 In general, the reaction of HO• with organic compounds, at completion will produce H2 O, CO2 , and salts (www.h2o2.com). In the present work, the oxidizing potential of hydroxyl radicals produced by the Photo 39



Fenton or Photo catalytic process has been

to 10 KLD only and the ph between 3 to 4.

explored for the pre-treatment of high COD

The segregated high COD stream is collected

effluent of an API industry at a plant scale.

via a separate drain (other than the drains

2.0 THE EXPERIMENTAL SET-UP:

which carry low COD/ washing effluents). This drain leads the high COD effluent to the

2.1 The high COD stream effluent of M/s

effluent

Symbiotec Pharmalab Pvt. Ltd. is generated

experimental set up is full scale treatment

from production processes. The COD of this

system by Photo Fenton & Photo Catalytic

stream ranges between 39000 mg/l to 80000

pretreatment of the stream near the ETP

mg/l. The average flow/ generation of the

location. The schematic diagram of the

high COD stream at the going production

experimental set up is as per figure1 below:

treatment

plant

(ETP).

The

levels in the industry ranges between 3 KLD

Figure 1



2.2

The experiments were conducted from

March

2014

to

August

2014.

The

specification of UVA system used

in

treatment process is mentioned below: Table 1: Specification of UVA system used

mass with help of diffuser. Precautions taken for suspected interferences of residual H2 O2 in COD test (www.h2o2.com). 3.0

3.1 The theoretical dose of H2 O2 required

Important features

1

Model

GI 40 LP

2

5000

3

Flow rate (Liters / hour) Vo ltage

4

Current ( mA )

5A

H2 O2

5

Watts

166

(34)

6

Dimension Φ

OD-200mm, H300mm, L1000mm 125

9 11 12

for the degradation of COD calculated based on the stochiometric equation given below:

230

Maximu m operating pressure (psi) Dosage (μw.sec/cm2.)

8

EXPERIMENTAL

METHODOLOGY:

Sr.No.

7

THE

UV radiat ion wave length (nm) No. of UV lamps SS 316 Electropolished UV radiator dimensions

70,000 μw.sec/cm2 254n m

H2O + ½O2 (32/2) = (COD)

One mole H2 O2 liberates ½ mole of O 2 which is a measure for the oxidation of an equivalent amount of COD. Thus 2.13 mg/l of H2 O 2 is required to produce 1 mg/l of O2 (34/16=2.13) and 1mg/l of O 2 oxidizes

4 997 mm x 185mm x 295 mm

1mg/l of COD theoretically. 3.2

Practically,

cost

of

theoretically

calculated H2 O2 dose for liberation of O 2 for 2.3 The chemicals used in the treatment

the removal of COD, limits the use of H2 O2

process

Sulphate

in full quantity to satisfy complete COD

(FeSO 4.7H2O) of Fisher Scientific with

demand, which necessitates supplementing/

assay 98%, Titanium dioxide (TiO 2 ) of

boosting the oxidation process by dosing

Emplura with assay 98.5% and hydrogen

Ferrous Sulphate along with H2 O2 in

Peroxide (H2 O2 ) of commercial grade

presence

having purity of 50%. Analytical procedures

consideration in mind, H2 O2 doses were

for the determination of chemical oxygen

reduced to only 0.75% of theoretically

demand (COD) were conducted according to

calculated H2 O2 dose supplemented with

Standard Methods. Experimental results for

FeSO 4 @ 1/40th the H2 O2 dose. The FRP

COD were analyzed at regular interval of 24

coated cylindrical reactor of 8000 liters

hours. The oxygen is provided in reaction

capacity was used for the process as shown

were

Ferrous

of

UV

light.

Keeping

this



in figure 1 above. The high COD effluent

3.5 In experiments where the resultant COD

received at the experimental site had pH in

value was reduced below 20000 mg/l after

range of 3-4.

72 hours,

3.3 The experiments were conducted by treating effluent batches of 3500 liters, 4000 liters, 4500 liters, 5000 liters, 6000 liters and 8000 liters. In total 15 sets of experiments were conducted for different waste volumes. The FRP lined reactors were filled with given quantity of the waste stream and dosed with the Fenton reagent having a FeSO 4: H2O 2 in proportion of 1:40. The reactor volume was thoroughly agitated with the help of diffused air from the bottom through a blower. The thoroughly mixed high COD effluent of the reaction tank was circulated through the UV system axially

the experiment was terminated

and the effluent sent for primary treatment and secondary (biological) treatment in the ETP. In experiments where the COD values were not found to be reduced below 20000 ppm, the effluent was subjected to photo catalytic treatment by dosing TiO 2 . The TiO 2 was dosed @ 100 g per 1000 liters of the batch. The COD values were tested after 24 hrs of the TiO 2 dosing i.e. 96 hours after the experiments started. The pH of the effluent was raised up to 9 by lime addition and after retention of 3 hours and COD values were again tested. The experimental results are reported in Table 2.

from bottom to top @ 5 m3/h. 3.4 The COD was monitored after every 24 hours. The theoretical dosages of H2 O 2 were again calculated based on the remaining COD after every 24 hours treatment. Dosing of H2 O2 @ 0.75% of theoretical dose and addition of FeSO 4 @ 1/40th times of the H2 O 2 added was also done after every 24 hours. The agitation and circulation over the UV light was continued. The above process of re dosing of H2 O2 and FeSO 4 was repeated after each 24 hours, till the end of 72 hours of reaction.



Table 2: Experimental Results

15

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

R

S

T

U

8000

72000

230

9.20

40200

44.16

128.42

5.13

30800

57.22

98.4

3.94

26100

63.75

24900

65.41

800

15800

78.05

8000

52000

166.25

6.65

48000

7.69

153.25

6.13

42000

19.23

134.25

5.37

39000

25

37800

27.3

800

30200

41.92

8000

48300

154.25

6.17

41000

15.11

131

5.24

38700

19.87

123.75

4.95

34200

29.19

32300

33.13

800

24500

49.27

8000

56000

179

7.16

27000

51.78

86.25

3.45

20600

63.21

65.75

2.63

15800

71.78

13200

76.43

ET*

ET*

ET*

6000

80200

192.25

7.69

42600

46.88

102

4.08

38700

51.75

92.75

3.71

35700

55.49

33400

58.35

600

15300

80.92

6000

39000

93.5

3.74

20000

48.71

48

1.92

13000

66.66

ET*

ET*

ET*

ET*

ET*

ET*

ET*

ET*

ET*

6000

62800

150.5

6.02

30000

52.23

72

2.88

14000

77.71

ET*

ET*

ET*

ET*

ET*

ET*

ET*

ET*

ET*

6000

54200

130

5.2

22000

59.41

52.7

2.10

13200

75.64

ET*

ET*

ET*

ET*

ET*

ET*

ET*

ET*

ET*

6000

62000

148.5

5.94

35200

43.22

84.25

3.37

28200

54.52

67.5

2.70

14000

77.42

12000

80.64

ET*

ET*

ET*

5000

49000

97.75

3.91

37200

24.08

74.25

2.97

23000

53.06

46

1.84

15600

68.16

13800

71.83

ET*

ET*

ET*

5000

43700

87.25

3.49

24000

45.08

47.92

1.92

17500

59.95

34.9

1.39

14000

67.96

12800

70.71

ET*

ET*

ET*

4500

66000

118.5

4.74

29000

56.06

52.1

2.08

20000

69.69

36

1.44

13000

80.30

11200

83.03

ET*

ET*

ET*

4000

51600

82.5

3.3

28500

44.77

45.52

1.82

19300

62.59

30.82

1.23

14000

72.87

12500

75.77

ET*

ET*

ET*

4000

42000

67

2.68

35000

16.67

56

2.24

16000

61.90

ET*

ET*

ET*

ET*

ET*

ET*

ET*

ET*

ET*

3500

46000

64.25

2.57

22400

51.30

31.25

1.25

16000

65.22

22.5

0.9

13000

71.74

11400

75.22

ET*

ET*

ET*

COD remaining (mg/l) after sample treated with lime at pH 9 COD removal time of and%retention hrs 72 Hrs+ lime 3after treatment

H2O2 dose (kg) (0.75% of theoretical dose) ( After 24 Hrs) COD remaining mg/l after 48 hrs

% COD removal after 96 Hrs

14

COD remaining mg/l (After 96 hrs)

13

Activated TiO2 Added (g)

12


11

COD remaining mg/l after 72 hrs

10

H2O2 dose(kg) (0.75% of theoretical dose) (After 48 hrs)

9

FeSO4 Added (g) ( After 48 hrs )

8

% COD removal after 48Hrs

7

FeSO4 added (g) ( After 24 Hrs)

6


5

COD remaining (mg/l) after 24 hrs

4

H2O2 dose (kg) (0.75% of theoretical dose) (Zero Hours)

3

FeSO4 added (g) (Zero Hours)

2

Initial COD (mg/l) (Zero Hours)

A 1

Quantity of effluent in the batch. (ltrs)

Experiment. No.

*ET-Experiment Terminated



4.0 RESULTS AND DISCUSSIONS:

with/without varying dosages of the Photo-

4.1 Reduction of COD as high as 59.41%

Fenton or Photo catalytic Treatment.

could be achieved in the first 24 hours of the

4.3 However contrary to the observation at

experiment using Photo-Fenton (experiment

point no 4.2 above, the initial COD

8, table 2) which was found to be up to

reduction after 24 hours in experiment no 14

77.71 % (experiment 7, table 2). Barring a

was also low which picked up with time and

few experiments as discussed here in below,

at the end of 48 hours, the COD reduction of

the results of the experiments were found to

61.79% could be achieved.

be encouraging and the experimental data

indicative that certain batches of high COD

provide an avenue to use Photo Fenton

effluent may pose some initial resistance to

/Photo Catalytic methods for the reduction

oxidation

of high COD effluent.

composition, but later the reaction may

4.2 In some experiments (experiment no 2 &3), the reduction in COD was found be

due

to

This is

complex

chemical

speed up. Further investigation in this direction can be taken up by the researchers.

low and the reduction in first 24 hours was

4.4 More reduction in initial COD value was

not even up to 20% . As the experiment

observed in first 24 hrs of Fenton dosing. In

continued further, the reduction after 72

later stages of Fenton dosing after each 24

hours was only 25% and 29.19%. The

hrs intervals, the COD reduction was

further addition of photo catalytic TiO2 was

comparatively low. It indicates that the COD

also not able to reduce the COD values

reduction

below 20000 ppm. These two experiments

reaction kinetics resembles to follow first

point

complex

order reaction kinetics, however further

in the

investigations are essential to fortify this

out

towards

certain

chemicals/ refractory chemicals

effluent batch which did not degrade even

in

the

present

experiments

inference.

after 96 hours. Further investigations is required to establish as to what complex chemicals pose difficulty in COD reduction using Photo Fenton and Photo catalytic methods,

whether

in

such

cases

the

treatment be continued beyond 96 hours

4.5

The addition of Photo Catalyst TiO 2

along with UV light in reaction mass was also found to play positive role as Fenton reagent played with UV light. Further investigations are recommended to ascertain the role of Photo Catalyst TiO 2 by reversing 44



the order of the chemical addition i.e. adding

4.8

TiO2 first and using Photo Fenton in the

recommended to find out the optimum

later stages of experiment.

dosage of the H2 O2 , the proportion of H2 O2 :

4.6

Reaction time was maintained 1 to 4

days for maximum utilization of hydroxyl radicals and to reduce the consumption of H2 O 2 which played important role for oxidation process. The reductions in COD value were observed as reaction time was increased

(Tiwari

&

Upadhyay 2013,

Further

investigations

are

also

FeSO 4 in the Fenton reagent, optimum dosage of the photo catalyst TiO2, the exposure time and dose of UV light required to decompose the high COD effluent so as to have proper operational control on the treatment process. 4.9

The results indicate that effluent

Paphane and Ramirez 2013, Ma Y. S.

characteristics and its complexity can also

et.al.2012, Upadhyay &Mistry 2012, Tiwari

play a notable role which may have limiting

and

effects on the degradability & oxidation

Jagan

investigation

2013).

However

are

recommended

further for

optimization of the reaction time. 4.7 It was observed that there is interference of residual H2 O2 in COD test which was eliminated by addition of sodium bisulphate (traces) and lime by raising the pH up to 9 of the sample before COD analysis. By removing the H2 O2 interference before COD test (experiment No. 1 to 5, 9 to 13 and 15) showed 3.5 % to 12% reduction in COD value. The interference in COD test due residual H2 O 2 detected by adding 2 to 4 drops of Starch Indicator (S.I.) in sample so sample colour turned to ink blue which indicated that residual un reacted H2 O2 are present in sample which may further react with potassium dichromate in COD test and as a result show falls high COD (h2o2.com).

process.

Elemental

analysis

can

be

conducted for every effluent batch to know the actual chemical composition in effluent which will further open up avenues of investigation for the optimization of the experimented treatment method. 5.0 CONCLUSION: Pretreatment of complex and high COD effluent

of

active

pharma

ingradient

industry, before subjecting it to primary and secondary (biological – ASP) treatment using Photo Fenton and Photo catalytic Oxidation in combination is very effective in reduction of COD. The experiments were conducted at a full scale and this method is being used in the industry M/s Symbiotec Pharmalab Ltd. The method can be further 45



investigated by the researchers/ industries

KLD: Kiloliter/day

for application elsewhere in other industrial

HO•: Hydroxyl radical

effluents.

However

there

are

minor

operational & maintenance issues like TiO 2

API: Active Pharmaceutical Ingredients

addition which sticks on UV lamps which

SEZ: Special Economic Zone

require frequent cleaning. On the contrary

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ACKNOWLEDGEMENT: The authors

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