2005 Min Etal Watres 2

7/29/2019 2005 Min Etal Watres 2

1/8

Water Research 39 (2005) 49614968

Electricity generation from swine wastewater using microbial

fuel cells

Booki Mina, JungRae Kima, SangEun Oha, John M. Regana,b, Bruce E. Logana,b,

aDepartment of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA 16802, USAbThe Penn State Hydrogen Energy (H2E) Center, The Pennsylvania State University, University Park, PA 16802, USA

Received 27 June 2005; received in revised form 26 September 2005; accepted 28 September 2005

Abstract

Microbial fuel cells (MFCs) represent a new method for treating animal wastewaters and simultaneously producing

electricity. Preliminary tests using a two-chambered MFC with an aqueous cathode indicated that electricity could be

generated from swine wastewater containing 83207190 mg/L of soluble chemical oxygen demand (SCOD) (maximum

power density of 45 mW/m2). More extensive tests with a single-chambered air cathode MFC produced a maximum

power density with the animal wastewater of 261 mW/m2 (200O resistor), which was 79% larger than that previously

obtained with the same system using domestic wastewater (14678 mW/m2) due to the higher concentration of organic

matter in the swine wastewater. Power generation as a function of substrate concentration was modeled according to

saturation kinetics, with a maximum power density ofPmax 225mW=m2

(fixed 1000O resistor) and half-saturation

concentration ofKs 1512 mg=L (total COD). Ammonia was removed from 19871 to 3471 mg/L (83% removal). In

order to try to increase power output and overall treatment efficiency, diluted (1:10) wastewater was sonicated andautoclaved. This pretreated wastewater generated 16% more power after treatment (11074 mW/m2) than before

treatment (9674 mW/m2). SCOD removal was increased from 88% to 92% by stirring diluted wastewater, although

power output slightly decreased. These results demonstrate that animal wastewaters such as this swine wastewater can

be used for power generation in MFCs while at the same time achieving wastewater treatment.

r 2005 Elsevier Ltd. All rights reserved.

Keywords: Microbial fuel cell; Electricity; Swine wastewater; Animal wastewater; Power generation

1. Introduction

Large volumes of high-strength wastewaters are

produced annually from industrial and agriculture

operations. For example, it is estimated that

5.8 107 tons of animal manures are generated each

year in the US alone (Dentel et al., 2004). The animal

wastewater must be treated to meet discharge regulationsprior to being released into the environment (Suzuki

et al., 2002; Maekawa et al., 1995) to avoid water

contamination and odor problems (Luo et al., 2002;

Westerman et al., 2000). High concentrations of nitrate

(NO3) and phosphate in wastewater can also contribute

to water pollution through eutrophication of surface

water (Luo et al., 2002; Ra et al., 2000). Many treatment

techniques have been proposed to remove inorganic or

organic pollutants from wastewater, but these processes

ARTICLE IN PRESS

www.elsevier.com/locate/watres

0043-1354/$- see front matterr 2005 Elsevier Ltd. All rights reserved.

doi:10.1016/j.watres.2005.09.039

Corresponding author. Department of Civil and Environ-

mental Engineering, The Pennsylvania State University, Uni-

versity Park, PA 16802, USA. Tel.: +1 814 863 7908.

E-mail address: [email protected] (B.E. Logan).
http://www.elsevier.com/locate/watreshttp://www.elsevier.com/locate/watres


2/8

entail high operational costs or large amounts of land for

treatment (Sevrin-Reyssac, 1998).

One approach to offset the costs of industrial and

animal wastewater treatment is to generate useful

amounts of bioenergy, such as hydrogen or methane

gas, from the organic matter in the wastewater while at

the same time accomplishing treatment (Logan, 2004;

Angenent et al., 2004; Rabaey and Verstraete, 2005).

Food processing wastewaters have been tested for

biological hydrogen production using fermentative

bacteria in several types of processes (Das and

Vezirog lu, 2001; Yu et al., 2002; Oh and Logan, 2005;

Van Ginkel et al., 2005). However, these processes have

not been widely used due to low energy recovery from

the organic matter (1.42.5 mole of hydrogen per mole

of hexose) and high operational costs (Logan, 2004;

Angenent et al., 2004; Oh and Logan, 2005).

Microbial fuel cells (MFC) have been developed that

can generate electricity directly from marine sediments,anaerobically digested sludge, food wastewaters, and

domestic wastewater. The amount of power produced

varies depending on the type of reactor and the specific

source of the organic matter. In laboratory and field

tests, 1025 mW/m2 (power normalized to the projected

surface area of the anode) is produced with sediment

fuel cells when the anode is placed into an anaerobic

marine sediment and the cathode is in the overlying

seawater containing dissolved oxygen (Reimers et al.,

2001; Bond et al., 2002; Delong and Chandler, 2002;

Tender et al., 2002). Using a single-chambered MFC

configuration (Liu et al., 2004; Liu and Logan, 2004;

Min and Logan, 2004), up to 26 mW/m2 (maximum

power density) was generated using domestic wastewater

(initial chemical oxygen demand (COD) of 200300 mg/

L) while at the same time removing up to 80% of the

COD (Liu et al., 2004). A flat plate MFC generated

7271 mW/m2, but under conditions that achieved only

42% COD removal (Min and Logan, 2004). Liu and

Logan (2004) generated a maximum of 14678 mW/m2

using wastewater with a single-chambered air-cathode

MFC operated in batch mode operation. In only a few

cases has there been a direct comparison of a single

wastewater with different types of MFCs. For example,

it was shown using a food processing wastewater thatpower could be increased from 8177 to 371710 mW/

m2 by using a single-chambered MFC instead of a two-

chambered MFC (Oh and Logan, 2005).

Animal wastewaters should provide a good source of

organic matter for electricity production using an MFC,

but so far this type of wastewater has not been examined

for electricity production (Logan, 2004). Potential

problems that could interfere with electricity generation

in a MFC relate to those that can affect other anaerobic

processes such as methane production: toxicity due to

the high concentrations of ammonia in the wastewater

or to volatile acids produced during hydrolysis and

fermentation of the substrates (Rittmann and McCarty,

2001). In this study, we demonstrate for the first time

that it is possible to produce electricity directly from

swine wastewater using a MFC, while at the same time

accomplishing wastewater treatment. Preliminary tests

were conducted using an aqueous cathode, two-cham-

bered MFC to demonstrate the feasibility of treatment

and for comparison of power densities achieved using

other substrates. More extensive tests were then

conducted using an air-cathode, single-chambered

MFC that is known to produce more power than the

two-chambered system (Liu and Logan, 2004; Oh et al.,

2004). Power output was examined as a function of

circuit load (resistance), wastewater strength, and

pretreatment by sonication of the wastewater. In

addition, we examined ammonia and phosphate con-

centrations in the raw and treated wastewater.

2. Materials and methods

2.1. Animal wastewater

Swine wastewater was collected from the Pennsylva-

nia State University Swine Farm (University Park, PA)

and kept in a refrigerator at 41C before use. The

wastewater was used as the inoculum for all MFC tests

without any modifications such as pH adjustments or

addition of nutrients or trace metals. Tests were

conducted using full-strength wastewater, except as

indicated, when the wastewater was diluted using

ultrapure water (Milli-Q system; Millipore Corp., New

Bedford, MA), autoclaved, or sonicated (Sonifier 450;

Branson Ultrasonic Co., CT; output control 7, duty

cycle 40%).

2.2. MFC configuration and operation

All experiments were conducted using MFCs operated

in fed-batch mode in a temperature-controlled room

(30 1C). A two-chambered MFC was used in initial tests

that contained two electrodes (anode and cathode), each

in a separate bottle (310 mL capacity, Corning Inc. NY,

USA). Each bottle was filled to 250 mL with wastewaterfor the anode and phosphate buffer solution (pH 7;

2.75g/L Na2HPO4+4.22g/L NaH2PO4 H2O) for the

cathode as previously described (Min et al., 2005). The

two bottles were connected with a glass tube (total

length 8 cm; inner diameter 1.3cm) with a proton

exchange membrane (NafionTM

117, Dupont Co.,

Delaware, USA) held by a clamp in the middle of the

tube. The electrodes (2.54.5cm each) were made of a

carbon paper (E-Teck) and connected via an external

circuit containing a single resistor (R 1000O, except

as noted). One side of the cathode was coated with a

catalyst (0.35 mg-Pt/cm

2

). The cathode chamber was

ARTICLE IN PRESS

B. Min et al. / Water Research 39 (2005) 496149684962


3/8

continuously aerated at 30 mL/min to provide dissolved

oxygen at the cathode.

Most tests were conducted using a single-chambered

MFC containing an air cathode, with liquid contained

inside a cylinder 4 cm long and 3 cm diameter chamber

(28 mL empty bed volume) as previously described (Liu

et al., 2004). The anode and cathode electrodes were

located on the opposite sides of the chamber, and the

reactor lacked a proton exchange membrane (PEM).

The electrodes were made of the same materials as those

used in the two-chambered system except a stainless steel

wire was used for connecting the electrodes (by

compression) to an external circuit. In some experi-

ments, the side of the cathode facing the air was coated

with polytetrafluoroethylene (designated as a PTFE

cathode) in order to reduce evaporation of water

through the cathode. This electrode was prepared by

applying a PTFE solution (50% by weight), drying at

room temperature for 10min, and then heating for10 min at 3801C.

2.3. Analysis

Total and soluble (filtered) COD of wastewater were

measured in duplicate (except as noted) using Standard

Methods (method 5220; HACH COD system, HACH

Company, Loveland, CO.; American Public Health

Association, American Water Works Association,

Water Pollution Control Federation, 1995). All samples

for soluble COD (SCOD) were filtered through a

0.45 mm pore diameter syringe filter, while total COD

(TCOD) measurements were conducted without treat-

ment. Measurements on inorganic compounds were

made in duplicate using procedures based on Standard

Methods (American Public Health Association, Amer-

ican Water Works Association, Water Pollution Control

Federation, 1995) for ammonia (Salicylate method),

phosphate (PhosVer 3 method), nitrate (Cadmium

reduction method), and nitrite (Diazotization chromo-

tropic acid method) (HACH).

The cell voltage across a resistor was measured using a

multimeter, and all data were automatically recorded by

a computer and a data acquisition system (2700,

Keithly). Power density, P (W/m2), was obtainedaccording to P IV=A, where I (A) is the current, V(V) is the voltage, and A (m2) is the projected surface

area of the anode. The Coulombic efficiency (CE) was

calculated based on current generation and the amount

of substrate removal during a MFC operation (Liu et

al., 2004; Oh et al., 2004; Min and Logan, 2004). The

maximum power density was determined by adding

fresh substrate to the MFC and establishing constant

power, and then varying the external resistance over a

range of 2400 KO and recording the voltage (typically

510 min per resistor). The power was then calculated

for each resistance as a function of the current.

3. Results and discussion

3.1. Power generation from swine wastewater using a

two-chambered MFC

Preliminary experiments conducted using a two-

chambered MFC demonstrated that electricity could

be generated using swine wastewater, and that the

bacteria needed were already present in the wastewater.

When non-diluted swine wastewater was added into the

two-chambered MFC, a circuit voltage of 2072mV

(7SD, n 90; 853h) was immediately generated

within only a few hours (Fig. 1A). This initial voltage

might have been due to both chemical and biological

factors based on the difference of the potential between

the two chambers. Thereafter, the voltage rapidly

increased due to biological activity, and stabilized at

12671 m V (n 114) over the following 47h period

(83140 h), resulting in a power density of 7.170.2mW/m2 (R 1000O) for this first inoculation of the MFC

with wastewater.

ARTICLE IN PRESS

00 50 100 150

30

60

90

120

150

Time, hr

Voltage,mV

00 50 100 150 200 250 300

10

20

30

40

50

60

Current density, mA/m2

Powerdens

ity,mW/m

2

0

200

400

600

800

Voltag

e,mV

Power density

Voltage

(A)

(B)

Fig. 1. Voltage generation (A) with full-strength animal

wastewater in a two-chambered MFC (1000O). Voltage and

maximum power generation (B) as a function of current density

obtained by varying the external circuit resistance from 4O to

400KO.

B. Min et al. / Water Research 39 (2005) 49614968 4963


4/8

After replacing the anode chamber solution four

times, we obtained a consistent and repeatable cycle of

power generation with non-diluted swine wastewater. By

varying the circuit resistance, it was determined from a

polarization curve that the maximum power that this

system could produce was 45 mW/m2 (141 mA/m2) at

1000O (Fig. 1B). This maximum power output is similar

to that obtained using this same two-chambered system

in several other studies using acetate (38 mW/m2, Min

et al., 2005; 43 mW/m2, Oh et al., 2004; 40 mW/m2, Kim

et al., 2005) or cysteine (39 mW/m2, Logan et al., 2005).

The observation that a similar maximum power output

was achieved with several different substrates is con-

sistent with previous findings that power generation in

this two-chambered MFC used by our research group is

limited by internal resistance and not by the power that

can be produced by bacteria with specific substrates

(Min et al., 2005).

3.2. Power generation using a single-chambered MFC

To demonstrate the potential for greater power

densities using animal wastewater, all further tests were

conducted with a single-chambered MFC. Acclimation

required more time with the single-chambered MFC

(114 h) than the two-chambered MFC (data not shown).

After two cycles of replacing the wastewater over 80 h,

the voltage reached a stable value of 35771 mV

(1000O), producing a maximum power density of

18271 mW/m2 with the swine wastewater (Fig. 2A).

Over a period of 44 h, the SCOD decreased by 27%, or

from 83207190 to 6090760 mg/L (triplicate measure-

ments). The CE for this measured COD removal was

8%. This CE is quite low, even compared to a value of

CE 20% obtained in tests with domestic wastewater

for this MFC (Liu and Logan, 2004).

The maximum power density for the single-cham-

bered MFC was 261 mW/m2 (200O, 1.4 A/m2; Fig. 2B).

This maximum power density is nearly 6 times that

obtained using the two-chambered system. The observa-

tion that power density is much larger using the single-

chambered than a two-chambered MFC is consistent

with previous studies. For example, the maximum power

density achieved using acetate in this two-chamberedsystem was 43 mW/m2 (Oh et al., 2004), while the same

substrate produced a maximum power density of

506 mW/m2 in a single-chambered MFC (Liu et al.,

2005a) under high substrate (saturation) conditions.

This difference in the maximum power density for these

two MFC systems when the same substrate is used is a

result of the different internal resistances of the systems

(Min et al., 2005).

The maximum power density with different substrates

varies for the single-chambered MFC, indicating that

the type of substrate can affect power output in this type

of MFC. In previous tests using the same MFC,

maximum power densities of 494 and 506 mW/m2 were

obtained using readily biodegradable substrates of

glucose and acetate (Liu and Logan, 2004; Liu et al.,

2005a). However, power output was lower using

butyrate (305 mW/m2), and decreased further for

domestic wastewater (146 mW/m2). These results de-

monstrate that the substrate, and perhaps the bacterial

community that developed during acclimation, affected

microbial kinetics and therefore the maximum power

density achievable with the swine wastewater.

3.3. Power generation as a function of wastewater

concentration

Power generation was measured as a function of

wastewater concentration to determine if the concentra-

tion of organic matter in the wastewater was limiting

power generation. The TCOD concentration of the

wastewater was varied by dilution from 49471 to

44707440 mg/L (SCOD range of 359732840750 mg/

L). The maximum power density obtained with a fixed

external resistance (1000O) showed a saturation-type

ARTICLE IN PRESS

00 20 40 60

50

100

150

200

250

300

Time, hr

Powerdensity,mW/m2

200

250

300

350

400

450

500

Voltage,mV

Power density

Voltage

0

50

100

150

200

250

300

350

0 500 1000 1500 2000 2500

Current density, mA/m2

Powerdensity,mW/m2

0

100

200

300

400

500

600

Voltage,mV

Power density

Voltage

(A)

(B)

Fig. 2. (A) Power and voltage generation using full-strength

wastewater in a single-chambereded MFC (1000 O) following a

200-h acclimation period. (B) Power density and voltage as a

function of current density obtained using external resistors of2O to 200KO.



5/8

relationship with respect to wastewater concentrations

(Fig. 3). The maximum power density at this resistance

was Pmax 225 mW=m2

, with a half-saturation concen-

tration of Ks 1510 mg=L (TCOD). The finding of asaturation-type relationship for power output as a

function of substrate concentration is consistent with

other studies using acetate or butyrate as a substrate in

this single-chambered MFC (Liu et al., 2005a).

The CE of substrate removal was determined by

measuring the TCOD and SCOD of the solutions after

the voltage decreased to less than 100 mV ($14 mW/m2).

The CEs measured at each substrate concentration

decreased from 26% to 10% with an increase in

wastewater concentration (Fig. 3). This inverse relation-

ship between CE and substrate concentration is similar

to that observed by Liu et al. (2005a). They found that

the CE decreased from 28% to 13% (R 1000O) using

acetate in the same type of MFC, when substrate

concentration increased from 80 to 800 mg/L. It isthought that part of this relationship between CE and

substrate concentration is due to the effect of oxygen

transfer into the system through the cathode. The higher

the substrate concentration the longer the period of time

needed to fully degrade the substrate. As the time period

increases, more oxygen can leak into the system causing

aerobic removal of the substrate, and lowering the

overall CE. Substrate can also be removed using

alternate electron acceptors, for example through sulfate

reduction, heterotrophic denitrification, and methano-

genesis.

3.4. Other factors affecting power generation

Several other factors were examined with respect to

power output, including wastewater pretreatment by

sonication or autoclaving, and stirring the wastewater. It

was hypothesized that there would be relatively less

electricity generation from the particulate organic

matter than from the soluble organic matter due to

slower degradation kinetics for particulate material

(Bougrier et al., 2004) and the limited diffusion of the

particulate material into the biofilm to the electrode

surface, where the electrochemically active bacteria are

located. For example, sonication has been shown to

increase biogas production in anaerobic digestors

(Tiehm et al., 2001; Bougrier et al., 2004). To decrease

the time needed to fully degrade the biodegradable

material in the sample during an experiment, the

wastewater was diluted (1:10).

Sonication (20min) increased the SCOD of diluted

wastewater by 19%, or from 1300740 to 1550780 mg/

L, but did not change the total COD (1940780 mg/L).

The increase in the SCOD came from the solids, as

indicated by a decrease in TSS from 250750 to74725 mg/L. When the sonicated and original diluted

wastewaters were used in MFC tests, there was

essentially no change in the maximum power density.

The sonicated wastewater produced a maximum power

density of 10575 mW/m2 (829 h), while the untreated

wastewater produced 10174 mW/m2 (532 h) (Fig. 4).

COD removals using the sonicated animal wastewater

were 85% for the TCOD and 91% for SCOD (after 72 h

operation; final TCOD 290720 mg/L and SCOD

140720 mg/L), while those for the untreated wastewater

were 89% and 90% (final TCOD 220740 mg/L;

SCOD 130710 mg/L), respectively. The CE for the

sonicated wastewater was 6.8%, while that for the un-

treated wastewater was 7.2%. Given that these differ-

ences are in general quite small, wastewater sonication

ARTICLE IN PRESS

Initial TCOD concentration, mg/L

Powerdensity,mW/m

2

0

0 1000 2000 3000 4000 5000

20

40

60

80100

120

140

160

180

200

Coulombicefficiency,%

5

10

15

20

25

30

35

Fig. 3. Power density (K) and Coulombic efficiency (CE; &)

as a function of initial TCOD concentrations for animal

wastewater in a single-chambereded MFC (PTFE cathode;

1000O).

0

0 10 20 30 40 50 60 70 80

20

40

60

80

100

120

140

Time, hr

Powerdensity,mW/m

2

Raw AW

Sonicated AW

Fig. 4. Power generation from sonicated animal wastewater

(AW; diluted by 1/10) in a single-chambereded MFC (PTFE

cathode; 1000O).



6/8

alone does not appear at this time to be a useful way to

increase power densities or COD removals in MFCs.

Autoclaving the wastewater was also examined as a

method of treatment to increase power generation in the

MFC. Autoclaving the wastewater can kill anaerobic

bacteria, such as methanogens, that can result in a loss

of organic matter in a manner that does not generate

electricity. The maximum power density with the

autoclaved wastewater (82 or 84 mW/m2) in two tests

was not appreciably different than that obtained with

raw wastewater (77 or 79 mW/m2) (Fig. 5). The CE with

the autoclaved wastewater was slightly lower (17%), but

not substantially different from that with the raw

wastewater (20%). Thus, autoclaving alone is insuffi-

cient to appreciably alter power generation in the MFC.

The average power density of 11074 mW/m2 (330 h)

for the sonicated and autoclaved diluted wastewater was

significantly higher (p valueo0.001, t-test) than that of

raw wastewater (9674 mW/m2

; 526h) (Fig. 6). Thus,the combined pre-treatment of autoclaving and sonicat-

ing the wastewater increased power generation by 16%.

The reasons for this increase could include changes in

biodegradability of the organic matter, and changes in

the molecular weight or particle size spectra of the

organic matter. While power densities can be increased

by these two processes, however, it is not likely that such

pretreatment could be economical due to the high energy

input needed for both processes.

Another factor that was investigated to improve reactor

performance was stirring the wastewater. It has been

shown that slow proton transfer between the anode and

cathode can limit power generation (Liu et al., 2005b). It

was therefore speculated that stirring the water might

increase power density due to enhancing proton transport

to the cathode, and substrate transport to the anode. It

was found, however, that power generation decreased as a

result of stirring. The maximum power density was

significantly (po0:001, t-test) larger in the system withoutstirring (12873 mW/m2; 827 h) than in the system with

stirring (11872 mW/m2; 826 h) (Fig. 7). While the reason

for this change is not known, stirring may have decreased

the concentration gradient of volatile acids in the biofilm

produced from hydrolysis and fermentation of the organic

matter. Alternatively, stirring might also have increased

ARTICLE IN PRESS

0

0 30 60 90 120

20

40

60

80

100

120

Time, hr

Powerdensity,mW/m2

Autoclaved AW

Raw AW Raw AW

Autoclaved AW

Fig. 5. Power generation using autoclaved and raw animal

wastewater (AW; diluted by 1/10) in a single-chambered MFC

(1000O; non-PTFE cathode).

00 30 60 90 120 150

20

40

60

80

100

120

140

160

Time, hr

Powerdensity,

mW/m2

Raw AW

Sonicated and autoclaved AW

Fig. 6. Power generation from sonicated and autoclaved

animal wastewater (AW; diluted by 1/10) in a single-chamberedMFC (PTFE cathode; 1000O).

0

0 10 20 30 40 50 60

20

40

60

80

100

120

140

160

180

Time, hr

Powerden

sity,mW/m

2

with stirring

without stirring

Fig. 7. Power generation using animal wastewater (diluted by

1/10) in a single-chambered MFC with and without stirring

(PTFE cathode; 1000O).



7/8

the oxygen flux into the reactor by affecting the resistance

to oxygen mass transfer at the cathode, resulting in an

increase in the redox potential of the anode chamber, but

this situation was not examined further. Consistent with

this explanation, COD removal was increased when the

solution was stirred (90% TCOD and 92% SCOD

removal with stirring; 89% TCOD and 88% SCOD

removals without stirring; Fig. 7) while the CE with

stirring (5%) was also less than that (8%) without stirring.

3.5. Nitrogen and phosphate concentrations during MFC

treatment

Ammonia, nitrite, nitrate and phosphate concentra-

tions were examined to determine the effect of MFC

treatment on these parameters. After 100 h operation

using diluted (1:10) wastewater, ammonia was removed

by 8374% (from 19871 to 3470mg NH4-N/L) when

the SCOD was reduced from 1240720 to 120730 mg/L(8676% removal). The high removals observed here for

a reactor operating under anaerobic conditions was

surprising. Nitrite and nitrate concentrations increased

from 0.470.1 to 2.970.1mg NO2-N/L and 3.871.2 to

7.570.1 mg NO3-N/L. This increase in oxidized nitro-

gen suggests that nitrification was occurring, likely as a

result of oxygen diffusion through the cathode. Oxygen

diffusion through the cathode is known to result in a loss

of carbonaceous substrates to aerobic degradation, as

evidenced by low CE in MFCs (Liu and Logan, 2004).

The total amount of ammonia removal (164 mg NH4-N/

L) was much larger than the corresponding increases in

nitrite (2.5 mg NO2-N/L) and nitrate (3.7 mg NO2-N/L).

The low CE and low concentrations of nitrate and nitrite

suggest additional nitrogen removal through several

possible routes including denitrification, anaerobic

ammonia oxidation (anammox) (Rittmann and

McCarty, 2001; Dong and Tollner, 2003), nitrite

reduction by lithotrophic ammonia oxidizers (Zart and

Bock, 1998), or by some previously unobserved method

of ammonia oxidation coupled to electricity generation.

Further work is needed to better understand the process

by which nitrogen is removed in this MFC.

Orthophosphate concentrations (PO4-P mg/L) did not

decrease, and may have slightly increased (41714871 mg/L) during the reactor test cycle. The increase in

orthophosphate concentration could have been a result

of the low redox potential in the MFC which would

stimulate the release of stored phosphates in the bacteria

(Luo et al., 2002), or the conversion of organic

phosphorus in the wastewater to orthophosphate.

4. Conclusions

Electricity was generated using swine wastewater, at a

power density that depended on the type of MFC. The

maximum power density using a two-chambered MFC

was 45 mW/m2, while 6 times more power (261 mW/m2)

was generated using a single-chambered system,

although the CE was low (8%). Power generation

showed a saturation-type relationship with wastewater

concentration, with a half-saturation concentration

constant of Ks 1510 mg=L (TCOD). The combinedpre-treatment of sonication and autoclaving the waste-

water generated 16% more power (11074 mW/m2) than

that produced using a raw diluted wastewater

(9674 mW/m2). Stirring the wastewater in the MFC

reduced the power density. Electricity generation was

accompanied by 8676% removal of COD and 8374%

removal of NH4-N. However, phosphate concentrations

increased by 17% during treatment. These results

demonstrated the feasibility of using MFC technologies

to generate electricity and simultaneously treat swine

wastewaters, although additional studies are needed to

scale up and optimize the process.

Acknowledgments

This research was supported by the Natural Re-

sources Conservation Service of the United States

Department of Agriculture (63-3A75-3-150), the Na-

tional Science Foundation (BES 0331824), and the Paul

L. Busch Award from the Water Environment Research

Foundation (to BEL).

References

American Public Health Association, American Water Works

Association, Water Pollution Control Federation, 1995.

Standard Methods for the Examination of Water and

Wastewater, 19th ed. American Public Health Association,

Washington DC.

Angenent, L.T., Karim, K., Al-Dahhan, M.H., Wrenn, B.A.,

Domguez-Espinosa, R., 2004. Production of bioenergy and

biochemicals from industrial and agricultural wastewater.

Trends Biotechnol. 22, 477485.

Bond, D.R., Holmes, D.E., Tender, L.M., Lovley, D.R., 2002.

Electrode-reducing microorganisms that harvest energy

from marine sediments. Science 295, 483485.

Bougrier, C., Carrere, H., Battimelli, A., Delgenes, J.P., 2004.

Effects of various pre-treatments on waste activated sludge

in order to improve matter solubilisation and anaerobic

digestion. In: Proceedings of the Anaerobic Digestion 2004,

10th World Congress, vol. 2. Montreal, Canada, August

29September 2, 2004.

Das, D., Vezirog lu, T.N., 2001. Hydrogen production by

biological processes: a survey of literature. Int. J. Hydrogen

Energy 26, 1328.

Delong, E.F., Chandler, P., 2002. Power from the deep:

microbially powered fuel cells tap into an abundant

ecosystem energy circuit. Nat. Biotechnol. 20, 788789.

ARTICLE IN PRESS



8/8

Dentel, S.K., Strogen, B., Sharma, A., Chiu, P., 2004. Direct

generation of electricity from sludges and other liquid

wastes. Proceedings, IWA Conference on Resources from

Sludge. Singapore, March 23.

Dong, X., Tollner, E.W., 2003. Evaluation of anammox and

denitrification during anaerobic digestion of poultry man-

ure. Bioresource Technol. 86, 139145.Kim, J.R., Min, B., Logan, B.E., 2005. Evaluation of

procedures to acclimate a microbial fuel cell for electricity

production. Appl. Microbiol. Biotechnol, in press,

doi:10.1007/S00253-005-0066-4.

Liu, H., Logan, B.E., 2004. Electricity generation using an air-

cathode single chamber microbial fuel cell in the presence

and absence of a proton exchange membrane. Environ. Sci.

Technol. 38, 40404046.

Liu, H., Ramnarayanan, R., Logan, B.E., 2004. Production of

electricity during wastewater treatment using a single

chamber microbial fuel cell. Environ. Sci. Technol. 38,

22812285.

Liu, H., Cheng, S., Logan, B.E., 2005a. Production of

electricity from acetate or butyrate in a single chambermicrobial fuel cell. Environ. Sci. Technol. 39 (2), 658662.

Liu, H., Cheng, S., Logan, B.E., 2005b. Power generation in

fed-batch microbial fuel cells as a function of ionic strength,

temperature, and reactor configuration. Environ. Sci.

Technol. 39 (14), 54885493.

Logan, B.E., 2004. Extracting hydrogen and electricity from

renewable resources. Environ. Sci. Technol. 38, 160A167A.

Logan, B.E., Murano, C., Scott, K., Gray, N.D., Head, I.M.,

2005. Electricity generation from cysteine in a microbial fuel

cell. Water Res. 39 (5), 942952.

Luo, A., Zhu, J., Ndegwa, P.M., 2002. Removal of carbon,

nitrogen, and phosphorus in pig manure by continuous and

intermittent aeration at low redox potentials. Biosyst. Eng.

82, 209215.

Maekawa, T., Liao, C.M., Feng, X.D., 1995. Nitrogen and

phosphorus removal for swine wastewater using intermit-

tent aeration batch reactor followed by ammonium crystal-

lization process. Water Res. 29, 26432650.

Min, B., Logan, B.E., 2004. Continuous electricity generation

from domestic wastewater and organic substrates in a flat

plate microbial fuel cell. Environ. Sci. Technol. 38,

58095814.

Min, B., Cheng, S., Logan, B.E., 2005. Electricity generation

using membrane and salt bridge microbial fuel cells. Water

Res. 39, 942952.

Oh, S.E., Min, B., Logan, B.E., 2004. Cathode performance as

a factor in electricity generation in microbial fuel cells.

Environ. Sci. Technol. 38, 49004904.

Oh, S.E., Logan, B.E., 2005. Hydrogen and electricity produc-

tion from a food processing wastewater using fermentation

and microbial fuel cell technologies. Water Res., in press.

Ra, C.S., Lo, K.V., Shin, J.S., Oh, J.S., Hong, B.J., 2000. Biologicalnutrient removal with an internal organic carbon source in

piggery wastewater treatment. Water Res. 34, 965973.

Rabaey, K., Verstraete, W., 2005. Microbial fuel cells: novel

biotechnology for energy generation. Trends Biotechnol. 23,

291298.

Reimers, C.E., Tender, L.M., Ferig, S., Wang, W., 2001.

Harvesting energy from the marine sediment-water inter-

face. Environ. Sci. Technol. 35, 192195.

Rittmann, B.E., McCarty, P.L., 2001. Environmental Bio-

technology: Principles and Applications. McGraw-Hill,

New York.

Sevrin-Reyssac, J., 1998. Biotreatment of swine manure by

production of aquatic valuable biomasses. Agric. Ecosyst.

Environ. 68, 177186.Suzuki, K., Tanaka, Y., Osada, T., Waki, M., 2002. Removal of

phosphate, magnesium and calcium from swine wastewater

through crystallization enhanced by aeration. Water Res.

36, 29912998.

Tender, L.M., Reimers, C.E., Stecher, IIIH.A., Holmes, D.E.,

Bond, D.R., Lowy, D.A., Pilobello, K., Fertig, S.J., Lovley,

D.R., 2002. Harnessing microbially generated power on the

seafloor. Nat. Biotechnol. 20 (8), 821825.

Tiehm, A., Nickel, K., Zellhorn, M., Neis, U., 2001. Ultrasonic

waste activated sludge disintergration for improving anae-

robic stabilization. Water Res. 35 (8), 20032009.

Van Ginkel, S., Oh, S.E., Logan, B.E., 2005. Biohydrogen gas

production from food processing and domestic wastewaters.

Int. J. Hydrogen Energy 39 (16), 38193826.

Westerman, P.W., Bicudo, J.R., Kantardjieff, A., 2000. Upflow

biological aerated filters for the treatment of flushed swine

manure. Bioresource Technol. 74, 181190.

Yu, H., Zhu, Z., Hu, W., Zhang, H., 2002. Hydrogen

production from rice winery wastewater in an upflow

anaerobic reactor by using mixed anaerobic cultures. Int.

J. Hydrogen Energy 27, 13591365.

Zart, D., Bock, E., 1998. High rate of aerobic nitrification and

denitrification by Nitrosomonas eutropha grown in a

fermentor with complete biomass retention in the presence

of gaseous NO2 or NO. Arch. Microbiol. 169, 282286.

ARTICLE IN PRESS

http://localhost/var/www/apps/conversion/tmp/scratch_2/dx.doi.org/10.1007/S00253-005-0066-4http://localhost/var/www/apps/conversion/tmp/scratch_2/dx.doi.org/10.1007/S00253-005-0066-4

Documents

2005 Min Etal Watres 2