FILTER MEDIA TESTING METHODS: USE OF FILTERABILITY TEST...
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F ILTER M EDIA T ESTING M ETHODS : U SE OF FILTERABILITY TEST FOR WATER TREATMENT Şeyma N. İren, Ezgi Karaağaç, Edanur Özgür Marmara University - Environmental Engineering Department Filters & Optimal Operation Optimal operating conditions in a filtration system requires the following to be satisfied simultaneously: the best possible average filtrate quality the lowest possible filter head loss the highest volume of water that passes through each unit of filter area during the course of the run (unit filter run volume) INTRODUCTION Filterability experiments have been carried with two different coagulant types, namely Alum and FeCl3 and different coagulant dosage. The findings of this work can be summarized as follows: • The same filtration rate (5 m/h) and porosity (0.38) were used for all the coagulants. The filterability index of FeCl3 were lower than the Alum. • Carrying tests with the different porosity (0.38 and 0.42) of bed, the filterability index of FeCl3 was more better than the Alum when porosity was 0.38. • Carrying tests with the different filtration rate (5 and 10 m/h), The filterability index was more better at low filtration rate. CONCLUSION Ives’ Filterability Index (Ives, 1978) = 0 1 1 Good filterability is expressed by a low FI number low filtrate concentration low head loss (clogging) a high flow rate (approach velocity) accepting high inlet concentration during a long time of operation 0 5 10 15 20 25 30 35 40 5 m/hr 10 m/hr 13 m/hr Filterability Index (x10 3 ) Filtration Rate (m/hr) Alum Coagulant Dosage= 150 µM Porosity = 0.38 0 2 4 6 8 10 12 14 25 µM 50 µM 75 µM 100 µM 150 µM 200 µM 250 µM Filterability Index (x10 3 ) Coagulant Dosage (µM Al) Alum Filtration Rate = 5 m/h Porosity = 0.38 0 1 2 3 4 5 6 7 8 25 µM 50 µM 75 µM 100 µM 150 µM Filterability Index (x10 3 ) Coagulant Dosage (µM Al or Fe) Alum Ferric Chloride Filtration Rate = 5 m/h Porosity = 0.38 Filtration Rate = 5 m/h Porosity = 0.38 0 1 2 3 4 5 6 25 µM 50 µM 75 µM 100 µM 150 µM Filterability Index (x10 3 ) Coagulant Dosage (µM Al or Fe) Alum Ferric Chloride Filtration Rate = 5 m/h Porosity = 0.42 0 5 10 15 20 25 30 25 µM 50 µM 75 µM 100 µM 150 µM Filterability Index (x10 3 ) Coagulant Dosage (µM Al or Fe) Alum Filtration Rate = 10 m/h Porosity = 0.38 AIM OF THE STUDY 0 1 2 3 4 5 6 7 8 25 µM 50 µM 75 µM 100 µM 150 µM Filterability Index (x10 3 ) Coagulant Dosage (µM Al) Porosity=0.38 Porosity=0.42 Filtration Rate = 5 m/h Alum 0 1 2 3 4 5 6 25 µM 50 µM 75 µM 100 µM 150 µM Filterability Index (x10 3 ) Coagulant Dosage (µM Fe) Porosity=0.38 Porosity=0.42 Filtration Rate = 5 m/h FeCl 3 MATERIALS & PROCEDURE COAGULANT DOSAGES Alum P2 = 0.38 5m/hr FI FI*10^3 C/C0 25 µM 0.0041 4.122 0.31 50 µM 0.0033 3.330 0.16 75 µM 0.0044 4.422 0.24 100 µM 0.0037 3.749 0.24 150 µM 0.0073 7.287 0.32 200 µM 0.0099 9.919 0.59 250 µM 0.0132 13.196 0.69 RESULTS Filterability Index Measurement height of filtering media 5.8 cm and 6.2 cm diameter of the filter bed 40.14 mm Recorded data • Raw water (entering to the filter column) turbidity • Head loss • Time needed to collect certain amount of filter effluent Raw Water Preparation Raw water samples were prepared by mixing 1 mL kaolin clay stock solution with 1000 mL tap water. Filterability experiments were conducted with a size 1 mm of glass ball and repeated with two different porosity. The filter medium was loaded into filter cell of the filterability apparatus up to a marked level.Air bubbles were removed. Raw water was coagulated using 2 different coagulants; alum [Al2(SO4)3·18H2O] and FeCl 3 . Following rapid and slow mixing stages, the sample was filtered. 1 L of sample was flocculated by rapid mixing for 30 seconds and slow mixing for 10 minutes in all the experiments. • Filterability index is lower with respect to higher velocities. • Best filterability index was obtained with using 50 µM coagulant. To determine coagulant type and dosage by the Filterability Index. C (µM) C (mM) C (mg/L) C (mg/L) C (mg/L) C (µM) C (mM) C (mg/L) C (mg/L) C (mg/L) Al 25 0.025 0.7 Al 2 (SO 4 ) 3 4.3 Al 2 (SO 4 ) 3 .18H 2 O 8.3 Fe 25 0.025 1.4 FeSO 4 3.8 FeSO 4 .7H 2 O 7.0 Al 50 0.05 1.3 Al 2 (SO 4 ) 3 8.6 Al 2 (SO 4 ) 3 .18H 2 O 16.7 Fe 50 0.05 2.8 FeSO 4 7.6 FeSO 4 .7H 2 O 13.9 Al 75 0.075 2.0 Al 2 (SO 4 ) 3 12.8 Al 2 (SO 4 ) 3 .18H 2 O 25.0 Fe 75 0.075 4.2 FeSO 4 11.4 FeSO 4 .7H 2 O 20.9 Al 100 0.1 2.7 Al 2 (SO 4 ) 3 17.1 Al 2 (SO 4 ) 3 .18H 2 O 33.3 Fe 100 0.1 5.6 FeSO 4 15.2 FeSO 4 .7H 2 O 27.8 Al 150 0.15 4.0 Al 2 (SO 4 ) 3 25.7 Al 2 (SO 4 ) 3 .18H 2 O 50.0 Fe 150 0.15 8.4 FeSO 4 22.8 FeSO 4 .7H 2 O 41.7 • For both chemical, lowest filterability index was obtained using with 50 µM coagulant. Ferric chloride gives better result. • For FR=5 m/hr, Ɛ=0.42. If we compare Alum and Ferric Chloride amount they are almost same in filterability index with 75 µM coagulant dosage. • For FR=10 m/hr and Ɛ=0.48. Lowest filterability index was obtained using with ferric chloride. After 50 µM, FI is almost same. • If we compare with filtration rate, with same coagulant types and dosages, filterability index increases significantly with increasing in velocity. • Alum gives lower FI value in high porosity. FeCl 3 gives in low porosity.
Transcript of FILTER MEDIA TESTING METHODS: USE OF FILTERABILITY TEST...
FILTER MEDIA TESTING METHODS: USE OF FILTERABILITY TEST FOR WATER TREATMENT
Şeyma N. İren, Ezgi Karaağaç, Edanur ÖzgürMarmara University - Environmental Engineering Department
Filters & Optimal OperationOptimal operating conditions in a filtration system requires the following to be satisfied simultaneously:
the best possible average filtrate quality the lowest possible filter head loss the highest volume of water that passes through each unit of
filter area during the course of the run (unit filter run volume)
INTRODUCTION
Filterability experiments have been carried with two different coagulant types, namely Alum and FeCl3 and different coagulant dosage. The findings of this work can be summarized as follows:
• The same filtration rate (5 m/h) and porosity (0.38) were used for all the coagulants. The filterability index of FeCl3 were lower than the Alum.
• Carrying tests with the different porosity (0.38 and 0.42) of bed, the filterability index of FeCl3 was more better than the Alum when porosity was 0.38.
• Carrying tests with the different filtration rate (5 and 10 m/h), The filterability index was more better at low filtration rate.
CONCLUSION
Ives’ Filterability Index (Ives, 1978)
𝐹𝐼 =𝐶
𝐶0𝐻1
𝑉
1
𝑡
Good filterability is expressed by a low FI number
low filtrate concentration low head loss (clogging) a high flow rate (approach velocity) accepting high inlet concentration
during a long time of operation
0
5
10
15
20
25
30
35
40
5 m/hr 10 m/hr 13 m/hrF
ilte
rab
ility
In
de
x (
x10
3)
Filtration Rate (m/hr)
Alum Coagulant Dosage= 150
µM Porosity = 0.38
0
2
4
6
8
10
12
14
25 µM 50 µM 75 µM 100 µM 150 µM 200 µM 250 µM
Filt
era
bili
ty I
nde
x (
x10
3)
Coagulant Dosage (µM Al)
Alum Filtration Rate = 5 m/h
Porosity = 0.38
0
1
2
3
4
5
6
7
8
25 µM 50 µM 75 µM 100 µM 150 µM
Filt
era
bili
ty I
nde
x (
x10
3)
Coagulant Dosage (µM Al or Fe)
Alum
Ferric Chloride
Filtration Rate = 5 m/h
Porosity = 0.38
Filtration Rate = 5 m/h
Porosity = 0.38
0
1
2
3
4
5
6
25 µM 50 µM 75 µM 100 µM 150 µM
Filt
era
bili
ty I
nde
x (
x10
3)
Coagulant Dosage (µM Al or Fe)
Alum
Ferric ChlorideFiltration Rate = 5 m/h
Porosity = 0.42
0
5
10
15
20
25
30
25 µM 50 µM 75 µM 100 µM 150 µM
Filt
era
bili
ty I
nde
x (
x10
3)
Coagulant Dosage (µM Al or Fe)
Alum Filtration Rate = 10 m/h
Porosity = 0.38
AIM OF THE STUDY
0
1
2
3
4
5
6
7
8
25 µM 50 µM 75 µM 100 µM 150 µM
Filt
era
bili
ty I
ndex (
x10
3)
Coagulant Dosage (µM Al)
Porosity=0.38
Porosity=0.42Filtration Rate = 5 m/h
Alum
0
1
2
3
4
5
6
25 µM 50 µM 75 µM 100 µM 150 µM
Filt
era
bili
ty I
ndex (
x10
3)
Coagulant Dosage (µM Fe)
Porosity=0.38
Porosity=0.42Filtration Rate = 5 m/h
FeCl3
MATERIALS & PROCEDURE
COAGULANT DOSAGES
Alum P2 = 0.38 5m/hr
FI FI*10^3 C/C0
25 µM 0.0041 4.122 0.31
50 µM 0.0033 3.330 0.16
75 µM 0.0044 4.422 0.24
100 µM 0.0037 3.749 0.24
150 µM 0.0073 7.287 0.32
200 µM 0.0099 9.919 0.59
250 µM 0.0132 13.196 0.69
RESULTS
Filterability Index Measurement
height of filtering media 5.8 cm and 6.2 cmdiameter of the filter bed 40.14 mm
Recorded data• Raw water (entering to the filter column)
turbidity • Head loss • Time needed to collect certain amount of filter
effluent
Raw Water PreparationRaw water samples were prepared by mixing 1 mL kaolin clay stock solution with 1000 mL tap water.
Filterability experiments were conducted with a size 1 mm of glass ball and repeated with two different porosity.
The filter medium was loaded into filter cell of the filterability apparatus up to a marked level.Air bubbles were removed.
Raw water was coagulated using 2 different coagulants; alum [Al2(SO4)3·18H2O] and FeCl3.
Following rapid and slow mixing stages, the sample was filtered.
1 L of sample was flocculated by rapid mixing for 30 seconds and slow mixing for 10 minutes in all the experiments.
• Filterability index is lower with respect to higher velocities. • Best filterability index was obtained with using 50 µM coagulant.
To determine coagulant type and dosage by the Filterability Index.
C (µM) C (mM)C
(mg/L)C
(mg/L)C
(mg/L)C (µM) C (mM)
C (mg/L)
C (mg/L)C
(mg/L)
Al 25 0.025 0.7 Al2(SO4)3 4.3 Al2(SO4)3.18H2O 8.3 Fe 25 0.025 1.4 FeSO4 3.8 FeSO4.7H2O 7.0
Al 50 0.05 1.3 Al2(SO4)3 8.6 Al2(SO4)3.18H2O 16.7 Fe 50 0.05 2.8 FeSO4 7.6 FeSO4.7H2O 13.9
Al 75 0.075 2.0 Al2(SO4)3 12.8 Al2(SO4)3.18H2O 25.0 Fe 75 0.075 4.2 FeSO4 11.4 FeSO4.7H2O 20.9
Al 100 0.1 2.7 Al2(SO4)3 17.1 Al2(SO4)3.18H2O 33.3 Fe 100 0.1 5.6 FeSO4 15.2 FeSO4.7H2O 27.8
Al 150 0.15 4.0 Al2(SO4)3 25.7 Al2(SO4)3.18H2O 50.0 Fe 150 0.15 8.4 FeSO4 22.8 FeSO4.7H2O 41.7
• For both chemical, lowest filterability index was obtained using with 50 µM coagulant. Ferric chloride gives better result.
• For FR=5 m/hr, Ɛ=0.42. If we compare Alum and Ferric Chloride amount they are almost same in filterability index with 75 µM coagulant dosage.
• For FR=10 m/hr and Ɛ=0.48. Lowest filterability index was obtained using with ferric chloride. After 50 µM, FI is almost same.
• If we compare with filtration rate, with same coagulant types and dosages, filterability index increases significantly with increasing in velocity.
• Alum gives lower FI value in high porosity. FeCl3 gives in low porosity.
