Environ. Sci. Technol. 2011, 45, 340–344
Concurrent Desalination and
Hydrogen Generation Using
Microbial Electrolysis and
Desalination Cells
HAIPING LUO,† PETER E. JENKINS,‡ AND
Z H I Y O N G R E N * ,†
Department of Civil Engineering and Department of
Mechanical Engineering, University of Colorado Denver,
Denver, Colorado 80004, United States
Received July 1, 2010. Revised manuscript received
November 10, 2010. Accepted November 17, 2010.
The versatility of bioelectrochemical systems (BESs) makes
them promising for various applications, and good combinations
could make the system more applicable and economically
effective. An integrated BES called microbial electrolysis and
desalination cell (MEDC) was developed to concurrently desalinate
salt water, produce hydrogen gas, and potentially treat
wastewater. The reactor is divided into three chambers by
inserting a pair of ion exchange membranes, with each chamber
serving one of the three functions. With an added voltage of
0.8 V, lab scale batch study shows the MEDC achieved the highest
H2 production rate of 1.5 m3/m3 d (1.6 mL/h) from the cathode
chamber, while also removing 98.8% of the 10 g/L NaCl from the
middle chamber. The anode recirculation alleviated pH and
high salinity inhibition on bacterial activity and further increased
system current density from 87.2 to 140 A/m3, leading to an
improved desalination rate by 80% and H2 production by 30%.
Compared to slight changes in desalination, H2 production
was more significantly affected by the applied voltage and
cathode buffer capacity, suggesting cathode reactions were
likely affected by the external power supply in addition to the
anode microbial activity.
oped to simultaneously desalinate salt water and produce
electricity (10-12). This system has significant advantages
compared to traditional desalination processes, as it does
not require intensive energy inputs or high water pressure
(13).
The versatility of BESs makes them promising for various
applications. By using good combinations of complementary
functions, the system could be more applicable and economically effective. For example, ion exchange membranes
have been used in BESs to separate the anode and the
cathode, but the high resistance and costs made such
configurations difficult to scale-up. On the other hand, single
chamber, membrane-less BESs improved energy production
but suffered low energy recovery and contamination. Call
and Logan (14) reported that single chamber MECs doubled
H2 production rate to a maximum 3.12 m3 H2/m3 d compared
to two-chamber systems, but most single chamber MECs
experienced H2 loss due to microbial consumption and
substantial methane contamination. So far, no effective
methods have been found to inhibit methanogenesis
(5, 15, 16). The development of MDCs leads to a new
challenge: if membranes have to be applied in the system,
what would be the most beneficial way to use them. Anion
exchange membrane (AEM) and cation exchange membrane
(CEM) were used to separate the MDCs into three chambers,
with the anode chamber used for organic oxidization, the
cathode for current production, and the middle chamber for
desalination. The proof-of-concept study has shown a
desalination rate approaching 90%, but the current system
is restrained by significant pH variation and power output
fluctuation (11).
Considering the above, we developed an integrated BES
system called microbial electrolysis and desalination cell
(MEDC) to concurrently desalinate salt water, produce
hydrogen gas, and potentially treat wastewater. The advantage of this combination is to generate pure and collectable
hydrogen gas without dealing with the contamination or
voltage fluctuation and to achieve enhanced desalination
facilitated by external power supply. We also characterized
the effects of applied voltages, buffer strengths, and operational parameters on H2 production and salt removal. The
difference of ion balances across the chambers between this
system and the MDC system were also discussed.
Introduction
Materials and Methods
Water and energy are the two most pressing technological
issues facing the world. The social and economic developments are driving the search for sustainable supply of both
water and energy. Recently developed bioelectrochemical
systems (BESs) represent one of the newest approaches for
generating clean water and energy. BESs use microorganisms
to catalyze the oxidization of organic and inorganic electron
donors in the anode chamber and deliver electrons to the
anode. The electrons can be captured directly for current
generation (microbial fuel cells, MFCs) (1-3) or supplemented by external power input for producing other energy
carriers, including hydrogen and methane gas (microbial
electrolysis cells, MECs) (4, 5). The electrons can also be
used to produce chemicals (microbial chemical cells, MCCs)
or remediate contaminants (6-9). Most recently, a new type
of BES called microbial desalination cell (MDC) was devel-
Reactor Construction. The MEDC reactors were constructed
from polycarbonate, and the electrode chambers were
produced by drilling a hole with 3-cm diameter in a solid
block (Figure S1, Supporting Information) (17). Three
chambers were clamped together and divided by placing an
AEM (AMI 7001, Membranes international, NJ) between the
anode and middle desalination chambers and a CEM (CMI
7000, Membranes international, NJ) between the middle and
cathode chambers. After inserting the electrodes, the volumes
of the anode, middle, and cathode chamber were 25, 17, and
36 mL, respectively. Heat treated graphite brushes (25 mm
diameter × 25 mm length, Golden brush, CA) were used as
the anode (17), and a stainless steel mesh (Type 304,
McMaster, IL) was selected as the cathode material. The gas
produced at the cathode bubbled into the cathode chamber
and was collected using a sealed anaerobic tube glued to the
top of the reactor (14). The top of the tube was sealed with
a butyl rubber stopper and aluminum crimp top.
Reactor Start-up and Operation. The reactors were
inoculated from a mixed culture by transferring the preacclimated anodes of active acetate-fed MFCs as the actual
* Corresponding author phone: (303)556-5287; fax: (303)5562368; e-mail: [email protected].
†
Department of Civil Engineering.
‡
Department of Mechanical Engineering.
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10.1021/es1022202
 2011 American Chemical Society
Published on Web 12/01/2010
MEDC anodes. The anodic medium for both MFC and MEDC
contained (per liter): CH3COONa 1 g, Na2HPO4 4.58 g,
NaH2PO4 · H2O 2.45 g, NH4Cl 0.31 g, KCl 0.13 g, trace metals
solution 12.5 mL, and vitamin solution 12.5 mL (18). The
cathode chamber was filled with 50 mM phosphate buffer
solution (Na2HPO4 4.58 g/L, NaH2PO4 · H2O 2.45 g/L, pH )
7.0) unless mentioned otherwise. The middle chamber was
filled with 10 g/L NaCl solution for desalination. In a fedbatch operation mode, the anolyte and catholyte were
replaced every 24 h cycle to avoid significant pH change. In
the anode recirculation mode, the anolyte was continuously
recirculated from a 400 mL reservoir through the anode
chamber at a rate of 1.5 mL/min using a peristaltic pump
(Model 3385, Fisher Scientific Co., Fairlawn, NJ).
A fixed voltage was added to the circuit of MEDC reactor
using a programmable power source (model 3646A, Circuit
Specialists Inc., AZ). An external resistor (10 Ω) was connected
in series with the power supply negative lead and the cathode
for current calculation. A saturated Ag/AgCl reference
electrode was inserted into the anode chamber to measure
changes of the electrode potential.
Analyses and Calculations. The voltage across the external
resistor (Re) was recorded using a data acquisition system
(model 2700, Keithley Instruments, Inc. OH). The current
density (I, A) through the electrical circuit was determined
from the measured voltage (E, V) according to I ) E/Re. Salt
concentrations were evaluated by conductivity measurements using a conductivity meter (Sension 156, HACH Co.,
Loveland, CO). The Na+ and Cl- concentrations were
determined by using suppressed conductivity detection ion
chromatography (model 4500I, Dionex, CA). The volume of
H2 produced by the MEDC was measured by the modified
biochemical methane potential (BMP) test (19, 20). Specifically, the produced gas in the cathode chamber was
intermittently released into a 10 mL glass syringe until the
pressure equilibrates with atmospheric pressure. The gas
composition and volumetric fraction of H2 was analyzed by
using a 100 µL gastight syringe and a gas chromatograph
(model 8610C, SRI Instruments, CA) equipped with a thermal
conductivity detector with nitrogen as the carrier gas.
The accumulated H2 production was calculated by
VH2,t ) VH2,t-1 + Vh(xH2,t - xH2,t-1) + xH2,t(Vm,t - Vm,t-1)
(1)
where VH2,t and VH2,t-1 are cumulative H2 volumes at corresponding times, (Vm,t - Vm,t-1) is the gas production during
the time interval, xH2,t and xH2,t-1 are the volumetric factions
of H2 in the current and previous intervals, respectively, and
Vh is the volume of headspace in the cathode chamber (4).
The H2 production rate (QH2, mL H2/h) was calculated from
the accumulated H2 production and the operation time, given
by QH2 ) (VH2,t - V0)/t. The volumetric H2 production rate
(QV,H2, m3 H2/m3 d) was calculated as QV,H2 ) QH2/V, where
V is the volume of anode chamber. The cathodic hydrogen
recovery (rcat) was calculated by
rcat )
nH2
nCE
)
nH2
∫
t
t)0
(2)
Idt/2F
where nH2 is the moles of H2 actually produced at the cathode,
nCE is the moles that theoretically could produced from the
current (I, A), dt(s) is the interval over which data are collected,
2 is used to convert moles of electrons to moles of H2, and
F is Faraday’s constant (96485 C/mol electrons) (4).
The desalination rate (QD, mS/cm h) was calculated by
QD ) (Ct - C0)/t, where C0 and Ct are the initial and the final
conductivity of saltwater in the middle chamber over a
interval time of t. Electrochemical impedance spectroscopy
FIGURE 1. Accumulated H2 production and desalination
efficiency in MEDC during batch operation with an applied
voltage of 0.8 V. (Arrows indicate electrolytes replacement.)
(EIS) was used to determine the internal resistance for the
MEDC system by using a potentiostat (G 300, Gamry
Instruments Inc. NJ). EIS measurements were conducted at
the condition of open circuit voltage (OCV), by using the
anode as the working electrode and the cathode as the counter
and reference electrode. The internal resistances of the cell
were obtained from Nyquist plots, where the intercept of the
curve with the Zre axis is defined as the ohmic resistance
(21, 22).
Results
H2 Production and Desalination Performance in Batch
Mode. Concurrent desalination and hydrogen gas production
were observed soon after the transfer of the active MFC
anodes into the assembled MEDC reactors. To prevent
substrate limitations for bacteria and significant changes in
pH value, the anolyte and catholyte were replaced every 24 h.
Figure 1 shows that a total of 48.7 mL of H2 was produced
within 4 cycles (96 h) at an applied voltage of Eap ) 0.8 V, and
98.8% of the salt was removed from the middle chamber
during the same period. The maximum current density
obtained was 87.2 A/m3, and the cathodic hydrogen recovery
was 72%. The values are comparable to the operation of other
lab scale MEC systems (4, 16, 23, 24). Instead of the H2 loss
due to microbial consumption that was reported by many
single chamber MEC studies, the cathodic H2 loss in the
MEDCs should be attributed to the intermittent sampling,
gas bubble holdup on the cathode surface, and limited H2
diffusion across the membranes (4).
In an attempt to characterize the reaction kinetics during
the cycles, the H2 production rate and desalination rate
showed parallel variations, as both rates increased linearly
during the first 8-10 h and then decreased slowly until the
end of each batch (Figure 2). The highest rates of H2
production and desalination were both achieved at around
8-10 h of each batch, with the maximum H2 production rate
of 1.5 m3/m3 d (1.6 mL/h) and the maximum desalination
rate of 0.42 mS/cm h. A further characterization of pH and
anode open circuit potential (OCP) variation showed that
pH continuously declined during one batch cycle, from 7 to
around 5, while the anode OCP first decreased from -442
mV (vs Ag/AgCl) at the beginning to -490 mV at 10 h and
then increased to -428 mV at the end of the batch (Figure
S2). Figure 2 also shows that the highest reaction rates of
different batches declined gradually during the operation.
Such decline was presumably due to the increase of the
system ohmic resistance as a result of conductivity decrease
in the middle chamber during salt removal. The EIS
measurement showed the system resistance increased from
70-250 Ω at the beginning of one cycle to 850-1100 Ω at
end of the cycle, increasing by a factor of 4-16 (Figure S3).
Similar findings were observed in the MDC system as well
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FIGURE 2. Variations of H2 production (QH2) and desalination
rates (QD) during batch operation with an applied voltage of 0.8
V. (Arrows indicate electrolytes replacement.)
FIGURE 3. Effects of applied voltage on H2 production and
desalination in typical 24-h batch cycles.
as other MFC reactors, as the low electrolyte condition may
also increase the membrane solution interface resistance
(11, 25).
In conjunction with the conductivity measurements, the
desalination performance of the reactor was also examined
on the basis of both Cl- and Na+ mass increments in the
anolyte and catholyte, respectively. By comparing the
concentration change of Cl- (in anolyte) and Na+ (in
catholyte) between the beginning and end of each 24-h cycle,
it was observed that there were always more Na+ migrated
to the cathode than Cl- to the anode chamber. For each
batch, the average increase of Na+ in the catholyte was 1.00
( 0.05 mmol, while the average increase of Cl- in the anolyte
was 0.83 ( 0.03 mmol. This imbalance of ion transfer was
also confirmed by the molar ratio increase between Cl- and
Na+ left in the middle chamber at the end of each batch.
Effects of Applied Voltage and Catholyte Buffer Capacity
on System Performance. The effects of applied voltage on
H2 production and desalination were characterized by varying
the applied voltage from 0.4-0.8 V. Similar to many MEC
studies, the H2 production rates increased consistently with
the increasing voltage (Figure 3). By increasing applied voltage
from 0.4 V to 0.8 V, the average H2 production rate increased
by 2.6 times, from 0.23 mL/h to 0.6 mL/h. However, little
changes were observed in desalination efficiency with the
voltage variation. The average desalination rate varied from
0.17 mS/cm h at 0.4 V to 0.23 mS/cm h at 0.8 V, representing
only a 35% increase.
The consumption of protons for H2 evolution (MEC) or
oxygen reduction (MFC and MDC) generally causes the pH
to increase in the cathode chamber, especially when membranes are used. Therefore, a buffer solution has been widely
used to counter the pH change and stabilize the system
performance. Figure 4 shows the different effects of the
catholyte buffer concentration on H2 production and de342
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FIGURE 4. Effects of catholyte phosphate buffer concentration
on the system performance in terms of (A) accumulated H2
production and (B) desalination efficiency in 24 h of operation.
salination in the MEDC at an applied voltage of 0.8 V. Similar
to the applied voltage effects, H2 production appeared to be
more affected by the availability of PBS buffer than the
desalination. When no buffer was provided in the catholyte,
very little H2 (3.9 mL) was produced in the first 12 h, and then
the gas production stopped, presumably due to the limited
supply of proton. In contrast, similar amounts of H2
(16.1-17.2 mL) were produced from the cathode chamber
with 50, 100, or 200 mM phosphate buffer, respectively. The
gas production rates were also comparable. However, the
catholyte buffer capacity showed little effects on desalination,
as similar overall salt removal rates were observed in different
cycles with various buffer concentrations. Higher gas production and desalination rates were both observed at the
100 mM buffer level in the first 12 h of batch operation,
suggesting such concentration may be more compatible to
the electron and mass transfers in this MEDC system. The
pH change in the catholyte after each cycle was proportional
to the buffer concentration, as shown in Figure 5. For example,
the catholyte pH increased only slightly, from 7.0 to 7.3 when
200 mM PBS was used, while the pH increased to 12.5 when
no buffer was used. The pH of the anolyte decreased after
each cycle from 7.0 to between 5 and 6 when 50 mM of PBS
was used.
Effect of Anolyte Recirculation on System Performance.
During batch operation, the anode potential varied from -490
mV at 10 h to -428 mV at the end of each batch cycle, resulting
in a decrease of anode as well as system performance (Figure
S2). This change is largely due to the decrease of pH and
accumulation of Cl- at the anode chamber, which inhibited
anode microbial activity. To alleviate such problems, an
anolyte recirculation operation was conducted by recirculating the solution through a 400 mL feed reservoir and the
anode chamber. The flow rate was set at 1.5 mL/min using
FIGURE 5. pH changes of anolyte and catholyte at the end of
each batch cycle with different initial phosphate buffer
concentrations. Initial pH was 7.0, and all anolyte buffer
concentration was 50 mM to prevent interaction.
FIGURE 6. Accumulated H2 production and desalination
efficiency during anolyte-recirculation operation with an
applied voltage of 0.8 V. (Arrows indicate electrolytes
replacement.)
a peristaltic pump, generating a hydraulic retention time of
17 min in the anode chamber. As shown in Figure 6, with the
applied voltage of 0.8 V, the continuous operation produced
49.5 mL of H2 within 60 h and also removed 98.2% of the salt
from the middle chamber. The corresponding maximum H2
production rate was 2.03 mL of H2/h (1.95 m3/m3 day), and
the desalination rate was 0.76 mS/cm h. These improvements
are directly related to the significant increase of the system
current density, which was calculated as 140 A/m3 (anode
chamber), a 61% increase compared to the batch mode.
Discussion
The integration of desalination, H2 production, and potentially waste removal in the MEDC reactors provides new
applications for the bioelectrochemical systems. A recent
life cycle assessment (LCA) study shows that the chemical
production in BESs may provide more environmental benefits
compared to direct electricity generation and conventional
anaerobic treatment (26), and the multiple functions offered
by the MEDC are more likely to add further such benefits.
The results obtained from this study showed that the MEDC
can remove 98.8% and 98.2% of the salt in batch mode and
recirculation mode, respectively, as well as achieving high
H2 production rates. With an applied voltage of 0.8 V, the
maximum H2 production rate from the batch operation was
1.5 m3/m3 day, and the current density approached 87.2 A/m3,
comparable to other MEC systems with membranes (23, 27).
Anolyte recirculation further increased the current density
to 140 A/m3 and the H2 production rate to 1.95 m3/m3 day.
Also, compared to the proof-of-concept MDC study, comparable volumes of the anode, cathode, and middle chambers
were used, bringing this technology one step closer to
practice. Substrate removal in the anode was not focused in
the study, as the anolyte was replaced every 24 h in batch
mode.
In the MDC system for direct current generation, the
transfer of ionic species from the middle chamber is solely
driven by the anode microbial activity and is proportional
to the electrons delivered by the microbes from the anode
chamber (11, 12). However, the added external power supply
complicates the reactions and ion transfers in the MEDC. By
monitoring concentration changes of the two ion species in
individual chambers, we found that, though initially balanced,
there was 12-20% more Na+ transferred from the desalination chamber to the catholyte than Cl- to the anolyte within
one batch cycle. In the mean time, the pH of the desalination
chamber kept stable at 6.6-6.8, indicating no significant
proton or hydroxyl ion migration occurred. Such imbalance
of Na+ and Cl- transfer can be attributed to several factors,
such as more Cl- adsorption on the high-surface carbon brush
anode than the Na+ adsorption on the stain steel cathode,
other competitive across-membrane ion transfers such as
phosphate, protons, and hydroxyl ions, and higher reaction
kinetics on the cathode than on the microbial anode. One
other affecting factor might come from the external voltage
supply, as it provides external potential or driving force for
the cathode reactions. This may help explain the results of
why H2 production was significantly affected by the applied
voltage and cathode buffer capacity, while desalination was
only slightly changed with same variations. One possible
explanation is that the MEDC cathode H2 production was
primarily affected by the external power supply and proton
availability in the catholyte, but the desalination was mainly
limited by the anode electron transfer.
Repeated trends of H2 production and desalination were
observed in fed-batch operation, with the highest rates
occurred at 8-10 h during each 24-h cycle. Such pattern is
likely caused by the changes of anode microbial activity due
to the pH variation. As shown in Figure S2, the anode OCP
reached a negative peak at the same 8-10 h period, which
indicates a maximum microbial substrate utilization rate and
leads to the highest rates of H2 production and desalination.
However, with the pH kept declining to below 6, the microbial
activity was inhibited more significantly until the replacement
of new media. The recirculation of anolyte significantly
improved the system performance, leading to a 61% increase
in current density, 80% increase in desalination rate, and
30% increase in gas production. The differences in improvements support the hypothesis that the desalination is
primarily limited by the anode and suggest that the recirculation helped facilitated the mass transfer and lifted the
constraints on the anode chamber, such as pH drop,
accumulated Cl- concentration, and substrate variation. This
is also confirmed by a stable anode open circuit potential of
-440 mV as compared to the fluculation of the anode
potential in the batch mode.
As a new multifunctional process, the MEDC research is
facing many challenges that remain to be solved, such as pH
variation in the anode and cathode chambers, increased
ohmic resistance, and stack system development. Higher flow
rate in the anode and cathode chamber compared to the
middle chamber, or an anode-cathode flow through system
should improve the H2 production and waste treatment
efficiency, as well as reduce the imbalance of pH (28). On the
other hand, value-added chemicals, such as caustic solutions,
could be produced in the cathode chamber, as the catholyte
pH could easily reach 13 without a high buffer solution (6).
Biofilm was observed on the AEM shortly after the batch
operation, indicating membrane biofouling may be another
challenge to address. As the key components in the MEDC,
high flux, high stability, and low fouling potential ion
exchange membranes should also be investigated to reduce
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the cost and increase system performance. To reduce the
middle chamber salt solution to very low levels, the anode
solution was replaced or recirculated multiple times in this
study in order to eliminate pH and substrate limitations on
bacteria in the anode chamber. In practice, rather than using
an MEDC to accomplish completely salt removal, the
electrolyte flows can be comparable among the chambers
for more efficient partial water desalination. Such operation
will leave more salt in the middle chamber and alleviate the
pH variation and internal resistance increase problems. The
effluent can be either applied for direct beneficial uses such
as agricultural irrigation or groundwater recharge, where
higher salt limits are allowed (TDS 500-2000 mg/L), or used
as a pretreatment for downstream RO processing to reduce
the energy consumption and membrane fouling (12, 29).
Acknowledgments
This work was supported by the Office of Naval Research
(ONR) under Awards N000140910944 and N0001410M0232.
We thank Drs. John Regan, Shaoan Cheng, and Hong Liu for
the valuable discussions and Dr. Pei Xu for the measurement
of ion concentrations.
Supporting Information Available
Three additional figures. This material is available free of
charge via the Internet at http://pubs.acs.org.
Literature Cited
(1) Liu, H.; Logan, B. E. Electricity generation using an air-cathode
single chamber microbial fuel cell in the presence and absence
of a proton exchange membrane. Environ. Sci. Technol. 2004,
38, 4040–4046.
(2) Logan, B.; Hamelers, B.; Rozendal, R.; Schröder, U.; Keller, J.;
Freguia, S.; Aelterman, P.; Verstraete, W.; Rabaey, K. Microbial
Fuel Cells: Methodology and Technology. Environ. Sci. Technol.
2006, 40, 5181–5192.
(3) Ringeisen, B. R.; Henderson, E.; Wu, P. K.; Pietron, J.; Ray, R.;
Little, B.; Biffinger, J. C.; Jones-Meehan, J. M. High power density
from a miniature microbial fuel cell using Shewanella oneidensis
DSP10. Environ. Sci. Technol. 2006, 40, 2629–2634.
(4) Logan, B. E.; Call, D.; Cheng, S.; Hamelers, H. V. M.; Sleutels,
T. H. J. A.; Jeremiasse, A. W.; Rozendal, R. A. Microbial Electrolysis
Cells for High Yield Hydrogen Gas Production from Organic
Matter. Environ. Sci. Technol. 2008, 42, 8630–8640.
(5) Cheng, S. A.; Xing, D. F.; Call, D. F.; Logan, B. E. Direct Biological
Conversion of Electrical Current into Methane by Electromethanogenesis. Environ. Sci. Technol. 2009, 43, 3953–3958.
(6) Rabaey, K.; Butzer, S.; Brown, S.; Keller, J.; Rozendal, R. A. High
Current Generation Coupled to Caustic Production Using a
Lamellar Bioelectrochemical System. Environ. Sci. Technol.
2010, 44, 4315–4321.
(7) Rozendal, R. A.; Leone, E.; Keller, J.; Rabaey, K. Efficient hydrogen
peroxide generation from organic matter in a bioelectrochemical
system. Electrochem. Commun. 2009, 11, 1752–1755.
(8) Butler, C. S.; Clauwaert, P.; Green, S. J.; Verstraete, W.; Nerenverg,
R. Bioelectrochemical Perchlorate Reduction in a Microbial Fuel
Cell. Environ. Sci. Technol. 2010, 44, 4685–4691.
(9) Clauwaert, P.; Rabaey, K.; Aelterman, P.; De Schamphelaire, L.;
Ham, T. H.; Boeckx, P.; Boon, N.; Verstraete, W. Biological
denitrification in microbial fuel cells. Environ. Sci. Technol. 2007,
41, 3354–3360.
344
9
ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 45, NO. 1, 2011
(10) Jacobson, K.; Drew, D.; He, Z. Efficient salt removal in a
continuously operated upflow microbial desalination cell with
an air cathode. Bioresour. Technol. 2010, 102, 376–380.
(11) Cao, X. X.; Huang, X.; Liang, P.; Xiao, K.; Zhou, Y. J.; Zhang, X. Y.;
Logan, B. E. A New Method for Water Desalination Using
Microbial Desalination Cells. Environ. Sci. Technol. 2009, 43,
7148–7152.
(12) Mehanna, M.; Saito, T.; Yan, J. L.; Hickner, M.; Cao, X. X.; Huang,
X.; Logan, B. E. Using microbial desalination cells to reduce
water salinity prior to reverse osmosis. Energy Environ. Sci. 2010,
3, 1114–1120.
(13) Cath, T. Y.; Childress, A. E.; Elimelech, M. Forward osmosis:
Principles, applications, and recent developments. J. Membr.
Sci. 2006, 281, 70–87.
(14) Call, D.; Logan, B. E. Hydrogen production in a single chamber
microbial electrolysis cell lacking a membrane. Environ. Sci.
Technol. 2008, 42, 3401–3406.
(15) Call, D. F.; Merrill, M. D.; Logan, B. E. High Surface Area Stainless
Steel Brushes as Cathodes in Microbial Electrolysis Cells.
Environ. Sci. Technol. 2009, 43, 2179–2183.
(16) Hu, H. Q.; Fan, Y. Z.; Liu, H. Hydrogen production using singlechamber membrane-free microbial electrolysis cells. Water Res.
2008, 42, 4172–4178.
(17) Logan, B.; Cheng, S.; Watson, V.; Estadt, G. Graphite fiber brush
anodes for increased power production in air-cathode microbial
fuel cells. Environ. Sci. Technol. 2007, 41, 3341–3346.
(18) Ren, Z. Y.; Ward, T. E.; Regan, J. M. Electricity production from
cellulose in a microbial fuel cell using a defined binary culture.
Environ. Sci. Technol. 2007, 41, 4781–4786.
(19) Owen, W. F.; Stuckey, D. C.; Healy, J. B.; Young, L. Y.; Mccarty,
P. L. Bioassay for Monitoring Biochemical Methane Potential
and Anaerobic Toxicity. Water Res. 1979, 13, 485–492.
(20) Ren, Z.; Ward, T. E.; Logan, B. E.; Regan, J. M. Characterization
of the cellulolytic and hydrogen-producing activities of six
mesophilic Clostridium species. J. Appl. Microbiol. 2007, 103,
2258–2266.
(21) He, Z.; Mansfeld, F. Exploring the use of electrochemical
impedance spectroscopy (EIS) in microbial fuel cell studies.
Energy Environ. Sci. 2009, 2, 215–219.
(22) Ramasamy, R. P.; Ren, Z. Y.; Mench, M. M.; Regan, J. M. Impact
of initial biofilm growth on the anode impedance of microbial
fuel cells. Biotechnol. Bioeng. 2008, 101, 101–108.
(23) Liu, H.; Hu, H.; Chignell, J.; Fan, Y. Microbial electrolysis: novel
technology for hydrogen production from biomass. Biofuels.
2010, 1, 129–142.
(24) Lee, H. S.; Torres, C. I.; Parameswaran, P.; Rittmann, B. E. Fate
of H2 in an Upflow Single-Chamber Microbial Electrolysis Cell
Using a Metal-Catalyst-Free Cathode. Environ. Sci. Technol.
2009, 43, 7971–7976.
(25) Harnisch, F.; Schroder, U.; Scholz, F. The suitability of monopolar
and bipolar ion exchange membranes as separators for biological
fuel cells. Environ. Sci. Technol. 2008, 42, 1740–1746.
(26) Foley, J. M.; Rozendal, R. A.; Hertle, C. K.; Lant, P. A.; Rabaey,
K. Life Cycle Assessment of High-Rate Anaerobic Treatment,
Microbial Fuel Cells, and Microbial Electrolysis Cells. Environ.
Sci. Technol. 2010, 44, 3629–3637.
(27) Cheng, S.; Logan, B. E. Sustainable and efficient biohydrogen
production via electrohydrogenesis. Proc. Natl. Acad. Sci. U. S. A.
2007, 104, 18871–18873.
(28) Freguia, S.; Rabaey, K.; Yuan, Z. G.; Keller, J. Sequential anodecathode configuration improves cathodic oxygen reduction and
effluent quality of microbial fuel cells. Water Res. 2008, 42, 1387–
1396.
(29) Xu, P.; Drewes, J. E.; Heil, D.; Wang, G. Treatment of brackish
produced water using carbon aerogel-based capacitive deionization technology. Water Res. 2008, 42, 2605–2617.
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