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Shafiqur Rahman, Associate Professor
Md Saidul Borhan, Research Specialist
Agricultural and Biosystems Engineering
Electrolysis of Swine Manure Effluents
Using Three Different Electrodes: FE-FE,
AL-AL, and FE-AL
Waste to Worth Meeting, Seattle, April 02, 2015
Introduction
Removal of phosphorus and nitrogen from livestock
liquid manure is a challenge
Various techniques are used for the treatment of industrial
effluent
The biological processes are slow, need large area, high
treatment cost, and generates huge sludge
Electrocoagulation/Electrolysis is a potential treatment
technique for treating wastewater
Introduction
Electrocoagulation/Electrolysis technique uses DC power source
between electrodes immersed in the effluent and coagulant is
generated in situ
Performance of the electrolysis system depends on wastewater
chemistry, electrodes types, and power applied
The use of the electrolysis system in treating livestock wastewater
is limited
Objectives
To compare the performance of three different Fe-Fe,
Al-Al, and Fe-Al electrodes to improve the quality of
swine wastewater.
To determine the effect of current density levels on
total phosphorus (TP), chemical oxygen demand
(COD), and total organic carbon (TOC) removal.
To estimate the Electrical Energy Consumption
(EEC) per unit volume of effluents treated.
Materials and Methods
Swine Effluents
• Obtained from primary lagoon of Swine Research Unit
of NDSU and stored at 4˚C until treated by electrolysis
• Effluents were homogenized and characterized at room
temperature (25 ±2˚C)
ParametersMeasured
concentrations
pH 8.3 ± 0.1
EC (mS cm-1) 6.7 ± 0.1
TSS (mg L-1) 980 ± 50
TP (mg L-1) 35.3 ± 3.1
TOC (mg L-1) 490 ± 13
COD (mg L-1) 1577 ± 110
Materials and Methods
• Three current density levels 500, 1000 , and 2000 mA/cm2
were applied
• Electrolysis process was continued for 60 min
• Polarity of the electrodes was reversed every 5 min
• Effluents were sampled while electrolysis was in progress
at 5 intervals (5 or 10, 20, 30 or 40, and 60 min)
• Samples were kept overnight to be settled
• Supernatants before and after electrolysis were analyzed
for TP, COD, TOC, pH and EC.
Evaluation Criteria
Removal efficiencies (%) for TP, COD, & TOC
𝑅𝐸 =𝑪𝒊−𝑪𝒇
𝑪𝒊× 𝟏𝟎𝟎
Where, Ci = Initial concentrations
Cf = Final concentrations
Electrical Energy Consumption (kWh/m3)
𝐸𝐸𝐶 =𝑽×𝑰×𝒕
𝟑𝟔𝟎𝟎×𝑸𝒆𝒇𝒇𝒍𝒖𝒆𝒏𝒕𝒔
Where, V = DC voltage applied
I = Current applied (mA)
t = Electrolysis time (s)
Q = Volume of effluents (L)
Results and Discussions
Al-AL electrodes
Al-Fe electrodes
Treated samples for 60 min using different electrodes at 21 mA/cm2
Initial swine liquid
manure
Results and Discussions
Treated samples in test tubes (from left to right) after 0, 10, 20, 30, 40, and 60 min of electrolysis using Al-AL electrodes at 21 mA/cm2
0 10 20 30 40 60 min
0102030405060708090
100110
0
30
0
60
0
90
0
12
00
15
00
18
00
21
00
24
00
27
00
30
00
33
00
36
00
39
00
TP R
E (%
) at
10
mA
cm
-2
Time (s)
Fe-Fe
Fe-Al
Al-Al
TP Removal Efficiency
TP Removal Efficiency
0
10
20
30
40
50
60
70
80
90
100
1100
30
0
60
0
90
0
12
00
15
00
18
00
21
00
24
00
27
00
30
00
33
00
36
00
39
00
TP R
E (%
) at
21
mA
cm
-2
Time (s)
Fe-Fe
Fe-Al
Al-Al
0102030405060708090
100110
0
30
0
60
0
90
0
12
00
15
00
18
00
21
00
24
00
27
00
30
00
33
00
36
00
39
00
CO
D R
E (%
) at
10
mA
cm
-2
Time (s)
Fe-Fe
Fe-Al
Al-Al
COD Removal Efficiency
0102030405060708090
100110
0
30
0
60
0
90
0
12
00
15
00
18
00
21
00
24
00
27
00
30
00
33
00
36
00
39
00
CO
D R
E (%
) at
21
mA
cm
-2
Time (s)
Fe-Fe
Fe-Al
Al-Al
COD Removal Efficiency
0
10
20
30
40
50
60
70
80
90
100
110
0
30
0
60
0
90
0
12
00
15
00
18
00
21
00
24
00
27
00
30
00
33
00
36
00
39
00
TOC
RE
(%)
at 1
0 m
A c
m-2
Time (s)
Fe-Fe
Fe-Al
Al-Al
TOC Removal Efficiency
0102030405060708090
1001100
30
0
60
0
90
0
12
00
15
00
18
00
21
00
24
00
27
00
30
00
33
00
36
00
39
00
TOC
RE
(%)
at 2
1 m
A c
m-2
Time (s)
Fe-Fe
Fe-Al
Al-Al
TOC Removal Efficiency
Energy Consumption
0102030405060708090100110
05
101520253035404550
0
30
0
60
0
90
0
12
00
15
00
18
00
21
00
24
00
27
00
30
00
33
00
36
00
39
00
TP R
E at
5 m
A c
m-2
CD
, %
EEC
, kW
h m
-3
Time, s
EEC_Fe-Fe EEC_Fe-Al EEC_Al-Al
TP_RE_Fe-Fe TP_RE_Fe-Al TP_RE_Al-Al
0102030405060708090100110
0
5
10
15
20
25
30
35
40
45
500
30
0
60
0
90
0
1200
15
00
1800
21
00
24
00
27
00
30
00
33
00
36
00
39
00
COD removal, EEC, and treatment times at 21 mA cm-2
CO
D R
E a
t 2
1 m
A c
m-2
CD
, %
EE
C, k
Wh
m-3
Time, s
EEC_Fe-Fe EEC_Fe-Al EEC_Al-Al
RE_Fe-Fe RE_Fe-Al RE_Al-Al
Current Density
(CD)
EC pH
Removal efficiency (%)Energy
(kWh m-3)
Sludge
(kg m-3)
Specific Energy
(kWh kg-sludge-1)TP COD TOC
Fe-Fe electrode
5 5.9 8.4 12 8 22 2.1 2.80 0.75
10 5.9 8.7 88 74 62 6.8 3.20 2.13
21 5.8 8.4 100 79 85 23.8 7.50 3.17
Fe-Al electrode
5 5.5 8.9 54 46 24 1.9 1.62 1.17
10 5.5 8.9 76 54 51 6.6 3.38 1.95
21 5.6 8.8 100 100 74 22.0 7.30 3.01
Al-Al electrode
5 6.7 8.4 100 30 46 2.5 2.43 1.03
10 6.6 8.3 100 38 43 6.8 3.22 2.11
21 6.6 8.4 100 77 69 23.6 4.70 5.02
Removal efficiencies, sludge collected, and EECs at three CDs(30 min treatment time)
Elemental analysis of electrolysis sludgeParameters Al-Al Fe-Fe Fe-Al
ppm
Ag 0.15c±0.00 1.42a*±0.32 0.85b±0.13
Al 148888a±381787 130c±164 83377b±234644
As 1.23c±0.00 80.74a±21.37 34.75b±6.19
B 31.53a±2.42 30.50a±2.24 26.08a±4.97
Ba 2.27b±1.13 5.56a±1.12 3.94ab±1.17
Ca 12422a±5501 13740a±8522 12969a±5620
Cd 1.44b±0.34 19.44a±7.20 6.16b±2.21
Ce 1.27c±0.83 5.42a±0.22 3.11b±0.347
Co 1.28c±0.24 7.95a±0.98 4.45b±0.30
Cu 33.76b±14.05 58.16a±7.31 54.53a±2.92
Fe 4142c±1234 337640a±81923 172416b±23751
K 6853a±93.57 3720b±595 4236b±617
Li 4.02b±1.24 1.15b±0.23 14.16a±5.00
Mg 6648ab±945 5419b±1317 10224a±3416
Mn 95.83c±26.48 506.60a±56.57 287.29b±9.92
Na 2469a±74 1566b±252 1726b±210
Ni 9.01c±1.93 49.23a±4.55 32.40b±1.45
P 6839a±3738 6917a±6795 11539a±6998
Pb 150.97a±113 1.83b±1.34 49.33ab±12.38
S 5020a±1757 2766a±1515 4144a±1757
Sb 1.51a±0.001 1.51a±0.001 1.51a±0.001
Se 5.84a±0.60 1.56b±0.003 2.48b±0.79
Si 39.23ab±1.84 50.64a±12.02 28.06b±8.13
Sn 2.57a±1.27 4.93a±1.68 3.29a±1.12
Sr 23.64a±11.51 25.81a±12.68 26.20a±11.51
Ti 9.75a±0.45 5.47b±2.18 7.66ab±0.52
Tl 2.36a±0.47 2.65a±0.60 3.33a±1.00
V 8.15a±3.35 7.35a±0.53 8.93a±1.52
Conclusions
TP, COD and TOC removal increased as currentdensities and treatment times increased.
Al-Al electrodes consumed the lowest energy (2.5 kWh m-3) at lower current density level (5 mA/cm2), but high TP removal efficiency (100%)
Energy consumption and sludge produced are directly proportional to current densities applied to the electrodes
Conclusions
Fe-Al electrodes outperformed Al-Al and Fe-Fe electrodes in treating COD at similar EEC.
Fe-Fe electrodes outperformed Fe-Al and Al-Al electrodes in treating TOC at similar EEC.
Electrolysis process deposited significant amount of elements in the sludge, thus likely to improve wastewater quality.
Acknowledgement
North Dakota Pork Council
State Board of Agricultural Research and Education (SBARE)
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