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

System Descriptions

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)

Go Bison!!

Questions????