Treatment of silk textile wastewater by chemical coagulation, fenton oxidation and

their combination.

Khanittha Charoenlarp,Tipanan Phangthong, Sunanta Punteaum, and Mayuree Aomsomboon

Department of Textile Chemistry Engineering, Rajamangala University of Technology Krungthep

Objective

• To Investigate the efficiency of silk textile wastewater treatment.

Content

• Introduction• Methods• Results • Conclusions

Introduction

Textile is one of the important sectors in Thailand.

Silk is known as “Queen of Textiles”.

Introduction

Silk product community in Surin

Silk worms Silk cocoons Boiling the silk cocoons

Reeling Bleaching and dyeing Weaving

Environmental concerns

• The wastewater from bleaching and dyeing process was not properly treated and discharged into the environment.

The main problem of dyeing wastewater treatment

• How to remove the contamination of dyes in wastewater which is mainly complex structure compound and toxic.

Wastewater treatment in dyeing industry

• Biological processes

• Physico-Chemical processes

Coagulation flocculation

• Chemical coagulants cause formation of a sludge phase that can be separated by density difference.

• Major coagulants:

– Al2(SO4)3.14H2O (Alum)

– FeCl3.6H2O

– Fe2SO4

Fenton oxidation method

• Discovered by Henry John Horstman Fenton in the1890.

• Applied for the decolorization of effluents from the textile dyeing process.

(Kim,T.H.,et al.,2004)

Fenton oxidation method

• Fenton's Reagent : Hydrogen Peroxide combined with an Iron catalyst.

• Creates multiple highly reactive powerful oxidizers:– Hydroxyl radical: OH0

– Peroxide free radical: HO20

H.J.H. Fenton.J. Chem. Soc. 1894, 65, 889.

Method• Analysis of silk textile wastewater.• Study the optimum condition and the

treatment efficiency of– Chemical coagulation – Fenton oxidation – A combination between Chemical

coagulation and Fenton oxidation method

Analysis of silk textile wastewater

• The silk textile wastewater from Surin province, Thailand was used in this study.

• The properties of wastewater to be analyzed were pH, COD, BOD, SS, and TS.

Measurements

pH

conductrometer

turbidimeter

Measurements

Total solid and suspended solid

Results

Properties of silk dyeing wastewater

Parameter Mean measureement

value

SD Standard Value

pH (25oC) 4.16 0.2 5.5 - 9

COD (mg/L) 1669.24 76.50 <120

BOD (mg/L) 386.60 23.55 <20

SS (mg/L) 541.60 34.16 <50

TS (mg/L) 8289.60 261.87 <3000

Chemical coagulation experiment

• The influence parameters for the chemical coagulation– Type and amount of coagulants– Type and amount of coagulant aids– Initial pH

Chemical coagulation parameter

Condition Value

Coagulants (Al2SO4 and Fe2SO4)

0.4, 0.6, 0.8, 1.2, 1.6, 2.0, and 2.4 g/L

coagulant aids (Ca(OH)2 and cationic polymer)

0.2, 0.4, 0.6, and 0.8 g/L

pH 5, 6, 7, 8, and 9

Rapid stirring rate (rpm) 100

Slow stirring rate (rpm) 20

The effect of pH value and types of coagulants 90.6%

Co

lor

rem

ova

l ef

fici

ency

(%

)

Initial pH

1.2 g/L Al2SO4

1.2 g/L Fe2SO4

5 6 7 8 90

10

20

30

40

50

60

70

80

90

100

67.7%

The effect of chemical coagulant dosages

0.4 0.8 1.2 1.6 2 2.4

-20

0

20

40

60

80

100

120

Color removal

COD removal

Eff

icie

ncy

(%

)

Al2SO4 dosages (g/L)

97.1%

61.6%

The effect of chemical coagulant aids types and dosages

Color removal

COD removal

Eff

icie

ncy

(%

)

2.4 g/L Al2SO4 2.4 g/L Al2SO4 +0.4 g/L Lime

2.4 g/L Al2SO4 +0.4 g/L Polymer

98.8%

70.8%

98.9%

65.9%

97.1%

61.6%

The influence parameters of the Fenton oxidation

• Initial pH

• Fe2SO4 dosages

• H2O2 dosages

Fenton oxidation parameter

Condition ValueH2O2 1.2, 2.4, 3.6, 4.8, and 6.0 g/L

FeSO4 0.2, 0.4, 0.6, 0.8, and 1.0 g/L

pH 2,3, 4 and 5

The effect of initial pH

2 3 4 550

55

60

65

70

75

80

85

90

95

100

Color removal

COD removal

initial pH

Eff

icie

nc

y (

%)

The effect of the ferrous dosages

0.2 0.40.6000000000000010.8 10

10

20

30

40

50

60

70

80

90

100

Color removal

COD removal

Ferrous dosages (g/L)

Eff

icie

nc

y (

%)

91.5%

66.5%

The effect of the H2O2 dosages

1.2 2.4 3.6 4.8 60

10

20

30

40

50

60

70

80

90

100

Color removal

COD removal

Eff

icie

ncy

(%

)

H2O2 dosages + 0.8 g/L Fe2SO4

91.3%

67.5%

90.8%

66.9%

The efficiency of silk dyeing wastewater treatment by combination chemical coagulation and Fenton oxidation

Chemical coagula-tion

Fenton oxidation Coagulation + Fenton

0.00

20.00

40.00

60.00

80.00

100.00

120.00

98.8491.30

99.97

70.81 67.50

91.54

Color removal (%) COD removal (%)

Conclusions

• The chemical coagulation and Fenton oxidation method was limited when wastewater contains high concentration of SS and COD.

• The combination of chemical coagulation and Fenton oxidation were more efficient than one.

Recommendations

• To compare the cost of each method.• To compare the sludge of each method.• To reduce pollution from the source.

Acknowledgement

• Rajamangala University of Technology Krungthep for financial support.

Thank you all for your attention

Silk product community in Surin

Silk worms Silk cocoons Boiling the silk cocoons

Reeling Bleaching and dyeing Weaving