water

Review
A Critical Review on the Advancement of the Development of
Low-Cost Membranes to Be Utilized in Microbial Fuel Cells
Alok Tiwari 1 , Niraj Yadav 1 , Dipak A. Jadhav 2,3, * , Diksha Saxena 1 , Kirtan Anghan 1 , Vishal Kumar Sandhwar 1
and Shivendu Saxena 1

1 Department of Chemical Engineering, Parul Institute of Technology, Parul University,

Vadodara 391760, Gujarat, India; alok.tiwari30232@paruluniversity.ac.in (A.T.);
2203052200001@paruluniversity.ac.in (N.Y.); diksha.saxena8882@paruluniversity.ac.in (D.S.);
200305103009@paruluniversity.ac.in (K.A.); vishal.sandhwar8850@paruluniversity.ac.in (V.K.S.);
shivendu.saxena8938@paruluniversity.ac.in (S.S.)
2 Department of Environmental Engineering, College of Ocean Science and Engineering, Korea Maritime and
Ocean University, 727 Taejong-ro, Yeongdo-gu, Busan 49112, Republic of Korea
3 Department of Civil and Environmental Sciences, JSPM University, Pune 412207, Maharashtra, India
* Correspondence: deepak.jadhav1795@gmail.com; Tel.: +91-8208179186

Abstract: Microbial fuel cells provide a promising solution for both generating electricity and treating
wastewater at the same time. This review evaluated the effectiveness of using readily available
earthen membranes, such as clayware and ceramics, in MFC systems. By conducting a compre-
hensive search of the Scopus database from 2015 to 2024, the study analyzed the performance of
various earthen membranes, particularly in terms of wastewater treatment and energy production.
Ceramic membranes were found to be the most effective, exhibiting superior power density, COD
removal, and current density, with values of 229.12 ± 18.5 mW/m2 , 98.41%, and 1535.0 ± 29 mW/m2 ,
respectively. The review emphasizes the use of affordable resources like red soil, bentonite clay,
CHI/MMT nanocomposites, and Kalporgan soil, which have proven to be effective in MFC applica-
tions. Incorporating earthen materials into the membrane construction of MFCs makes them more
cost-effective and accessible.

Citation: Tiwari, A.; Yadav, N.; Jadhav,

Keywords: proton exchange membrane; clay membrane; microbial fuel cells; single chambered design
D.A.; Saxena, D.; Anghan, K.;
Sandhwar, V.K.; Saxena, S. A Critical
Review on the Advancement of the
Development of Low-Cost
Membranes to Be Utilized in 1. Introduction
Microbial Fuel Cells. Water 2024, 16, Water and energy scarcity are the critical and major global issues that need sustain-
1597. https://doi.org/10.3390/ able and economic solutions. In recent years, researchers have increasingly focused on
w16111597 developing effective and ecofriendly solutions to address these challenges [1]. Nuclear and
Academic Editor: Fanying Kong fossil fuels are non-renewable and have the greatest impact on total energy consumption.
However, the use of fossil fuels is a major contributor to carbon dioxide emissions, which
Received: 24 April 2024 can lead to water pollution and global warming, posing significant risks to human life [2].
Revised: 18 May 2024 Early detection of water quality issues is crucial to ensure the reliability of wastewater
Accepted: 27 May 2024
treatment facilities and drinking water sources. With freshwater scarcity and increasing
Published: 3 June 2024
pollution from industrial, agricultural, and domestic sources, it is essential to maintain
treatment efficacy for the sake of public health and environmental protection. Currently,
there are two critical challenges: energy scarcity and water depletion are the major issue
Copyright: © 2024 by the authors.
worldwide [3]. The first issue is made worse by over-dependence on limited energy sup-
Licensee MDPI, Basel, Switzerland. plies and growing energy needs, while the second is caused by fast industrialization and
This article is an open access article expanding consumption patterns. Addressing these challenges requires us to explore safe,
distributed under the terms and eco-friendly energy alternatives for various sectors. Fossil fuel depletion, projected to occur
conditions of the Creative Commons by 2040–2042 for oil and gas and by 2112 for coal, highlights the urgent need for sustainable
Attribution (CC BY) license (https:// energy solutions [4]. As a result, researchers are focusing on renewable energy sources with
creativecommons.org/licenses/by/ the goal of achieving environmental sustainability and economic viability to mitigate the
4.0/). global energy crisis and preserve water resources [5].

Water 2024, 16, 1597. https://doi.org/10.3390/w16111597 https://www.mdpi.com/journal/water

 sustainable energy solutions [4]. As a result, researchers are focusing on renewable energy
sources with the goal of achieving environmental sustainability and economic viability to
Water 2024, 16, 1597 2 of 21
mitigate the global energy crisis and preserve water resources [5].
Microbial fuel cells (MFCs) offer a unique solution to tackle some of the world’s most
pressing challenges, particularly in sustainable energy production and wastewater treat-
Microbial
ment [6]. fuel cellsenergy
As renewable (MFCs) offer abecome
sources uniqueincreasingly
solution to crucial,
tackle some MFCsofharness
the world’s
the
most pressing challenges, particularly in sustainable energy
power of microorganisms to convert organic matter directly into electricity [7]. production and wastewater
This not
treatment [6]. As renewable energy sources become increasingly crucial, MFCs harness the
only provides a renewable energy source but also reduces dependence on fossil fuels, mit-
power of microorganisms to convert organic matter directly into electricity [7]. This not only
igating greenhouse gas emissions and combating climate change. Additionally, MFCs of-
provides a renewable energy source but also reduces dependence on fossil fuels, mitigating
fer a sustainable approach to wastewater treatment by simultaneously treating
greenhouse gas emissions and combating climate change. Additionally, MFCs offer a
wastewater and generating electricity. This approach addresses two critical issues in tan-
sustainable approach to wastewater treatment by simultaneously treating wastewater and
dem, and the technology can bring wastewater treatment closer to home, making it more
generating electricity. This approach addresses two critical issues in tandem, and the
accessible and affordable, especially in underserved areas [1,8].
technology can bring wastewater treatment closer to home, making it more accessible and
Nafion is the most commonly used membrane in MFCs, but at the same time poses
affordable, especially in underserved areas [1,8].
several challenges, such as high cost, biofouling, substrate losses, and oxygen leakage [9].
Nafion is the most commonly used membrane in MFCs, but at the same time poses
Therefore, it is essential to explore alternative membranes to improve MFC efficiency and
several challenges, such as high cost, biofouling, substrate losses, and oxygen leakage [9].
affordability. MFCs have two primary applications: sustainable electricity generation and
Therefore, it is essential to explore alternative membranes to improve MFC efficiency and
wastewater
affordability.treatment.
MFCs have Severaltwovariables
primaryimpact MFC efficiency,
applications: including
sustainable anodegeneration
electricity material
selection, chemicaltreatment.
and wastewater media, proton exchange
Several membranes,
variables impact biocatalysts,
MFC efficiency, and including
device arrange-
anode
ment [10]. However, the practicality of using MFCs in industries
material selection, chemical media, proton exchange membranes, biocatalysts, is limited mainly
andby the
device
cost of membrane materials, which limits their usability. The increased
arrangement [10]. However, the practicality of using MFCs in industries is limited mainly internal resistance
ofbyMFCs is another
the cost problemmaterials,
of membrane that affects theirlimits
which effectiveness. CapitalThe
their usability. costsincreased
are also signifi-
internal
cant, with electrode expenses (20–30%) for both anodes and cathodes
resistance of MFCs is another problem that affects their effectiveness. Capital [11] and membrane
costs are
expenses (50–60%)
also significant, [12]electrode
with representing a considerable
expenses (20–30%) forportion of the capital
both anodes costs. Solving
and cathodes [11] and
these problems
membrane can help
expenses us fully[12]
(50–60%) utilize MFCs in real-world
representing applications
a considerable portion and increase
of the capitaltheir
costs.
effectiveness in wastewater treatment and sustainable energy generation
Solving these problems can help us fully utilize MFCs in real-world applications and [11].
Overtheir
increase the past few years,
effectiveness inmany researchers
wastewater haveand
treatment worked on microbial
sustainable energy fuel cells with
generation [11].
positive outcomes. On 30 December 2023, a search was conducted on
Over the past few years, many researchers have worked on microbial fuel cells with the ScienceDirect™
database
positive using the keyword
outcomes. “microbial
On 30 December fuel acell,”
2023, which
search wasyielded
conducted a total
on ofthe7302 papers the
ScienceDirect™
fields of “biotechnology
database using the keyword applied microbiology’’
“microbial (5169)
fuel cell,” which and “energy
yielded fuels”
a total (1073),
of 7302 as
papers
shown in Figure
the fields 1. There has been
of “biotechnology a recent
applied in-depth study
microbiology” of microbial
(5169) and “energy fuel fuels”
cells as(1073),
a risingas
bioenergy
shown insource.
FigureVarious
1. There extensive
has been reviews
a recent have focusedstudy
in-depth on different areas, fuel
of microbial suchcells
as elec-
as a
trode structures, designs and configurations, challenges, applications, and
rising bioenergy source. Various extensive reviews have focused on different areas, such as microbial com-
munity dynamics
electrode [13].designs and configurations, challenges, applications, and microbial
structures,
community dynamics [13].

Figure
Figure1.1.Number
Numberofofpublished
publishedpapers
papersper
peryear
yearrelated
relatedtotoMFCs.
MFCs.

This review aimed to evaluate the low-cost membrane development for microbial fuel
cells over the past 8–9 years. It explored various MFC configurations, analyzed membrane
characteristics, and examined how other factors influence their performance. The objective
of this review was to identify the most suitable and cost-effective membrane options for
MFC applications by assessing various membrane types based on factors such as energy
recovery, current density, power density, and proton transfer efficiency. The study also
 This review aimed to evaluate the low-cost membrane development for microbial
fuel cells over the past 8–9 years. It explored various MFC configurations, analyzed mem-
brane characteristics, and examined how other factors influence their performance. The
Water 2024, 16, 1597 objective of this review was to identify the most suitable and cost-effective membrane 3 ofop-
21
tions for MFC applications by assessing various membrane types based on factors such as
energy recovery, current density, power density, and proton transfer efficiency. The study
discusses different
also discusses types
different of ceramic
types membranes
of ceramic membranes used
usedin in
MFCs,
MFCs,asasshown
shownin in Figure
Figure 2.
The
The goal
goal of
ofthis
thisresearch
researchwas
wastotoanalyze
analyzeglobal
globalscientific
scientificoutcomes
outcomes related
related to
toMFCs.
MFCs. The
The
investigation utilized data from the Scopus database.
investigation utilized data from the Scopus database.

Figure 2.
Figure 2. Different
Different membranes
membranes per
per year
year related
relatedto
toMFCs.
MFCs.

2.
2. Fundamentals
Fundamentals of of MFCs
MFCs
Microbial
Microbial fuel cellstransform
fuel cells transformwastewater
wastewaterbiomass
biomass into a dependable
into a dependable source of electric-
source of elec-
ity by utilizing the electrocatalytic qualities of bacteria. They comprise three
tricity by utilizing the electrocatalytic qualities of bacteria. They comprise three essentialessential parts,
the anode, cathode, and a separator or membrane. Also known as microbial
parts, the anode, cathode, and a separator or membrane. Also known as microbial electro- electrochemical
cells, they cells,
chemical are a practical
they are aand sustainable
practical way to produce
and sustainable way energy via aenergy
to produce biologicalviaprocess [14].
a biological
MFCs
process are[14].
available
MFCsin area variety
availableof in
configurations, but their fundamental
a variety of configurations, but theirdesign consistsde-
fundamental of
two chambers joined by an ion exchange membrane: an anodic compartment
sign consists of two chambers joined by an ion exchange membrane: an anodic compart- and a cathodic
compartment.
ment and a cathodicElectrodes, substrates,Electrodes,
compartment. an electrical circuit, and
substrates, an bacteria
electricalorcircuit,
microorganisms
and bacte-
are all included within these chambers [15]. Like conventional fuel cells,
ria or microorganisms are all included within these chambers [15]. Like conventional MFCs run on fuel
the
idea of redox reactions; however, instead of utilizing expensive metal catalysts,
cells, MFCs run on the idea of redox reactions; however, instead of utilizing expensive they obtain
their
metalenergy from
catalysts, liveobtain
they microbiological
their energysources [16].microbiological
from live Different organic sources
sources areDifferent
[16]. used to
generate an electric current. Microorganisms break down organic materials
organic sources are used to generate an electric current. Microorganisms break down or- to produce
protons, electrons, and carbon dioxide, which are then used to generate energy [17]. The
ganic materials to produce protons, electrons, and carbon dioxide, which are then used to
presence of the anolyte medium affects the microbial fuel cell (MFC) reaction process, as
generate energy [17]. The presence of the anolyte medium affects the microbial fuel cell
shown in Equations (1)–(3) [18].
(MFC) reaction process, as shown in Equations (1)–(3) [18].
+ −
Anode reaction:
Anode CHCH
reaction: 3 COOH
3COOH H2→
+ H+2 O O→2CO 2 +2 8H
2CO + 8H++ +8e8e− (1)
(1)
−
Cathode
Cathodereaction: 8H+8H
reaction: + +8e
+ 8e+− +2O 2 2→
2O →4H 4H2 O
2O
(2)
(2)
Overall reaction: CH3 COOH + 2O2 → 2H2 O + 2CO2 (3)
Overall reaction: CH3COOH + 2O2 → 2H2O + 2CO2 (3)
In the overall process, the substrate is broken down into carbon dioxide and water, with
In the overall
the concurrent process,ofthe
production substrate
energy is broken down
as a byproduct [19]. Byinto carbon dioxide
promoting and water,
the movement of
with the from
electrons concurrent production
the anode of energy
to the cathode in anasexternal
a byproductcircuit,[19]. By promoting
an MFC bioreactorthe move-
produces
ment of electrons
electricity from the
by extending theanode to thereactions.
electrode cathode inRemarkably,
an external circuit, an MFC
two distinct bioreactor
applications
produces
may electricity
be served by anby extending
operation of the electrode
MFC process.reactions.
ProcessRemarkably,
variables aretwothe
distinct appli-
membrane,
cations may
electrodes inbe
theserved byand
design, an operation
the MFC of the MFC process.
configuration, whichProcess variables
all affect are the mem-
the performance of
brane, Ion
MFCs. electrodes
exchangein the design, and
membranes the MFCfor
are essential configuration,
the buildingwhich all affect
of MFCs, thethey
just like perfor-
are
for fuel of
mance cells and Ion
MFCs. batteries [20]. membranes are essential for the building of MFCs, just like
exchange
they are for fuel cells and batteries [20].
2.1. Configuration of MFCs
MFCs require proper design to work efficiently. MFCs are built according to a variety
of architectural standards, and evaluation frequently focuses on elements such as power
output, stability, durability, and Coulombic efficiency. Moreover, based on the quantity
 2.1. Configuration of MFCs
Water 2024, 16, 1597 MFCs require proper design to work efficiently. MFCs are built according to a variety
4 of 21
of architectural standards, and evaluation frequently focuses on elements such as power
output, stability, durability, and Coulombic efficiency. Moreover, based on the quantity
of chambersor
of chambers orcompartments,
compartments,microbial
microbialfuel
fuelcells
cellsmay
maybe
beclassified
classifiedinto
intotwo
twogroups
groupsfor
for
optimization [16].
optimization [16].

2.1.1.Dual
2.1.1. DualCompartment
Compartmentof
ofMFC
MFC
Dualchamber
Dual chambermicrobial
microbialfuel fuelcells
cells(D-MFCs)
(D-MFCs)are areamong
amongthe themost
mostwidely
widelyused
usedandand
traditional varieties
traditional varieties of of microbial fuel cells.
cells. They
Theyarearebuilt
builtwith
withtwotwochambers
chambersthatthatvary
vary in
size
in and
size shape,
and including
shape, includingrectangular, U, and
rectangular, U, H
and shapes [21]. An
H shapes MFC’s
[21]. anode and
An MFC’s anodecathode
and
cathode compartments
compartments are connected
are connected by an external
by an external circuit circuit to facilitate
to facilitate electron
electron flowaand
flow and salt
abridge
salt bridge
or PEM or to
PEM to transfer
transfer ions. Microorganisms
ions. Microorganisms develop develop in the anolyte
in the anolyte or anode’s
or on the on the
anode’s
surface surface in regular
in regular D-MFCs. D-MFCs.
Protons Protons cross
cross the the membrane
membrane to reach
to reach the cathode
the cathode whilewhile
elec-
electrons
trons areare moved
moved to the
to the anode.
anode. AirAir or oxygen
or oxygen sparge
sparge or an
or an electrical
electrical terminal
terminal electron
electron ac-
acceptor are both present in the cathode
ceptor are both present in the cathode chamber. Forchamber. For the D-MFCs to produce energy,
produce energy, thethe
anaerobic
anaerobicanode
anodemustmustbebe maintained,
maintained, andandthethe
cathode chamber
cathode chamberconditions must
conditions be lowered
must be low-
so the so
ered separate operation
the separate of microbial
operation metabolic
of microbial processes
metabolic and proton
processes andoxidation in D-MFCs
proton oxidation in
results
D-MFCs in better
resultspower
in betterdensities.
power Nevertheless, they come they
densities. Nevertheless, with come
more complex
with more structures
complex
due to the way
structures due the twoway
to the chambers
the two arechambers
constructed areand separated.
constructed andIf the final material
separated. If the that
final
receives
material that receives electrons is oxygen, it also needs constant oxidation, primarilyair
electrons is oxygen, it also needs constant oxidation, primarily in the form of in
spargers,
the form asof seen in Figureas3 seen
air spargers, [16,22].
in Figure 3 [16,22].

Figure3.3.Dual
Figure Dualchamber
chamberMFC
MFC[23].
[23].

2.1.2.
2.1.2.Single
SingleCompartment
CompartmentMFCs MFCs
Oxygen
Oxygen serves as the lastelectron
serves as the last electronacceptor
acceptorin inmost
mostS-MFCs.
S-MFCs.In In certain
certain arrangements,
arrangements,
the
the cathode is left open to the air while the membrane and cathode arefirmly
cathode is left open to the air while the membrane and cathode are firmlycompressed
compressed
together.
together.Exoelectrogens
Exoelectrogensproduce
produce electrons that
electrons move
that move in the direction
in the of the
direction ofanode electrode
the anode elec-
while passing across the external circuit and arriving at the cathode [24,25].
trode while passing across the external circuit and arriving at the cathode [24,25]. Protons Protons in the
electrolyte travel across
in the electrolyte travel the membrane
across at the same
the membrane at thetime
same and arrive
time andatarrive
the cathode, where
at the cathode,
they assist in reducing oxygen levels in water. Anaerobic circumstances are
where they assist in reducing oxygen levels in water. Anaerobic circumstances are the only the only ones in
which exoelectrogens take place; hence, the anode compartment maintains
ones in which exoelectrogens take place; hence, the anode compartment maintains an an oxygen-free
environment. S-MFCs are flexible and simple, and they come in a various of configurations,
as shown in Figure 4 [16].
Water 2024, 16, x FOR PEER REVIEW 5 of 22

Water 2024, 16, 1597 5 of 21

oxygen-free environment. S-MFCs are flexible and simple, and they come in a various of
configurations, as shown in Figure 4 [16].

Figure 4.
Figure 4. Single
Single chamber
chamber MFC
MFC [25,26].
[25,26].

3.
3. Electrodes
Electrodes
Microbial
Microbial fuel
fuel cells
cells rely
rely on
on efficient
efficient anodes
anodes andand cathodes
cathodes to to operate
operate optimally.
optimally. The
The
selection
selection ofof anode
anode material
material is is critical,
critical, with
with biocompatibility,
biocompatibility, electrical
electrical conductivity,
conductivity, and
and
surface area being the top priorities. Biocompatible materials such as
surface area being the top priorities. Biocompatible materials such as graphite or carbon graphite or carbon
cloth
cloth are
are essential
essential for
for supporting
supporting the the resident
resident microbial
microbial communities
communities and and their
their metabolic
metabolic
activity [27,28]. High electrical conductivity is crucial for efficient electron
activity [27,28]. High electrical conductivity is crucial for efficient electron transport transport during
dur-
microbial
ing microbial oxidation, which directly impacts the MFC’s performance [29]. Anodes high
oxidation, which directly impacts the MFC’s performance [29]. Anodes with with
surface area promote
high surface microbial
area promote attachment,
microbial whilewhile
attachment, durability ensures
durability long-term
ensures functional-
long-term func-
ity [30]. Further investigation is required to understand the interplay
tionality [30]. Further investigation is required to understand the interplay between thebetween the anode’s
catalytic activity and
anode’s catalytic its compatibility
activity with specific
and its compatibility withmicrobial consortiaconsortia
specific microbial [31]. [31].
The cathode plays a complementary role in MFCs, facilitating the reduction reaction
The cathode plays a complementary role in MFCs, facilitating the reduction reaction
that balances the anode’s oxidation. Efficient cathodes require high catalytic activity for the
that balances the anode’s oxidation. Efficient cathodes require high catalytic activity for
reduction of electron acceptors such as oxygen. Promising cathode materials include carbon-
the reduction of electron acceptors such as oxygen. Promising cathode materials include
based materials, metals, and metal oxides [32]. A large surface area is equally important
carbon-based materials, metals, and metal oxides [32]. A large surface area is equally im-
for effective electron transfer and the reduction reaction. Durability is paramount for
portant for effective electron transfer and the reduction reaction. Durability is paramount
withstanding the harsh chemical environment within the cathode chamber. Moreover,
for withstanding the harsh chemical environment within the cathode chamber. Moreover,
good cathode conductivity ensures efficient electron flow from the anode, completing the
good cathode conductivity ensures efficient electron flow from the anode, completing the
MFC’s electrical circuit [33,34]. Our ongoing research endeavors to optimize these electrode
MFC’s electrical circuit [33,34]. Our ongoing research endeavors to optimize these elec-
properties, understand the underlying electrochemical kinetics, and explore novel electrode
trode properties, understand the underlying electrochemical kinetics, and explore novel
materials to amplify MFC performance across diverse applications.
electrode materials to amplify MFC performance across diverse applications.
3.1. Anode Reaction
3.1. Anode Reaction
In MFCs, selecting a proper coating for the electrodes is essential as it affects how
In MFCs,
interaction selectingwith
of bacteria a proper coatingAdditionally,
the anode. for the electrodes
it hasisaessential as it on
major effect affects how
electron
interaction of bacteria with the anode. Additionally, it has a major effect on
transport and processes involving protons that have a high reduction potential, especially electron
transport
on and processes
the cathode involving
when interacting protons
with thatsuch
materials haveasaoxygen.
high reduction potential, especially
High conductivity, chemical
on the cathode
stability when interacting
in wastewater with materials
streams, strong such as oxygen.
biocompatibility High conductivity,
with minimal chem-
toxicity to bacteria,
ical large
and stability inofwastewater
areas the surfacestreams,
that helpstrong biocompatibility
easily attach and spreadwith minimal
bacteria toxicity
on their to
surface
are all desirable qualities in anode material, as shown in Figure 5 [35]. It is also suggested
that they be highly adaptive and stable at low temperatures and in the pH range of 5
 Water 2024, 16, x FOR PEER REVIEW 6 of 22

Water 2024, 16, 1597

bacteria, and large areas of the surface that help easily attach and spread bacteria on6 their of 21
surface are all desirable qualities in anode material, as shown in Figure 5 [35]. It is also
suggested that they be highly adaptive and stable at low temperatures and in the pH range
to
of75 [36]. TheyThey
to 7 [36]. ought to be
ought to immune
be immune to biofouling
to biofoulingas as
well.
well.It Itcould
couldbebebeneficial
beneficialififthe
the
cost
cost of manufacturing were
of manufacturing werelow.low.In In
MFCMFC applications,
applications, carbon
carbon is a particularly
is a particularly good
good anode
anode material.
material. It can beIt found
can beinfound
manyindifferent
many different forms, including
forms, including activated activated carbon,
carbon, single- or
single- or multi-walled carbon nanotubes, carbon mesh, graphite granule
multi-walled carbon nanotubes, carbon mesh, graphite granule brushes, graphite plates, brushes, graphite
plates,
carboncarbon cloth, fibers,
cloth, carbon carbonsurface-modified
fibers, surface-modified stainless
stainless steel, graphitesteel,plates
graphite plates
or rods, or
as well
rods, as well as metallic anodes [37]. However, since metal anodes
as metallic anodes [37]. However, since metal anodes are also common, selecting the ap- are also common,
selecting
propriatethe appropriate
anode materialanode material
is crucial is crucial
in avoiding in avoiding
metal metal
corrosion, corrosion,
as shown as shown in
in Equations (4)
Equations (4)
and (5) [18]. and (5) [18].
+ + −−
CH3CH
COOH
3COOH H2→
+ H+2 O → 2CO
O 2CO2 +28H
+ 8H + +8e8e (4)
(4)
+ −
C2 HC
4O
2H2 4+
O2H 2 O 2→
2 + 2H O→2CO 2 +2 8H
2CO + 8H++ +8e8e− (5)
(5)

Figure5.5.Properties
Figure Propertiesof
ofelectrode
electrodematerials
materials[31].
[31].

3.2.
3.2.Cathode
CathodeReaction
Reaction
Protons
Protonsare
areproduced
producedin inthe
theanode
anodechamber
chamberand
andthen
thentravel
travelto
tothe
thecathode
cathodechamber
chamber
through
throughthe
thePEM.
PEM.Simultaneously,
Simultaneously,electrons
electronsgenerated
generatedatatthe
theanode
anodesite
sitereach
reachthe
thecathode
cathode
chamber via the external circuit [38].
chamber via the external circuit [38].
→ 2H
H2 2H
H2 → + 2e− −
+ + + 2e

+ + − −
O2 +O4H
2 + 4H + 4e→→2H
+ 4e 2O
2H 2O

This
Thissequence
sequenceof ofactions
actionsresults
resultsininaasteady
steadycurrent
currentflow
flowininthe
theexternal
externalcircuit.
circuit.The
The
yield of the cathode reaction depends on various factors, such as the type and
yield of the cathode reaction depends on various factors, such as the type and concentra- concentration
of theofoxidant,
tion the availability
the oxidant, of protons,
the availability the catalyst’s
of protons, performance,
the catalyst’s and theand
performance, electrode’s
the elec-
structure. Choosing
trode’s structure. the rightthe
Choosing catalyst, such assuch
right catalyst, platinum [39], activated
as platinum carbon,carbon,
[39], activated and other
and
metal
other catalysts [40] such
metal catalysts [40]assuch
(cobalt, titanium,
as (cobalt, and iron),
titanium, and is crucial
iron), for oxygen
is crucial reduction
for oxygen in
reduc-
the cathode chamber [38,41]. However, one of the major challenges in MFC
tion in the cathode chamber [38,41]. However, one of the major challenges in MFC tech- technology is
the low efficiency of the oxygen reduction reaction (ORR) that occurs at the
nology is the low efficiency of the oxygen reduction reaction (ORR) that occurs at the cath- cathode, as
shown
ode, asinshown
Figurein6.Figure
The cathodic reaction is
6. The cathodic affected
reaction is by various
affected byfactors,
varioussuch as cathode
factors, such as
configuration (air-cathode or aqueous cathode), whether cathodes
cathode configuration (air-cathode or aqueous cathode), whether cathodes are are biotic or biotic
abiotic,
or
electrode and catalyst materials, electrode dimensions, the cathode current collector, and
catholytes. The air-cathode MFC design has many advantages over the aqueous cathode,
provided that an appropriate gas diffusion layer prevents water leakage through the
Water 2024, 16, x FOR PEER REVIEW 7 of 22

Water 2024, 16, 1597 abiotic, electrode and catalyst materials, electrode dimensions, the cathode current collec- 7 of 21
tor, and catholytes. The air-cathode MFC design has many advantages over the aqueous
cathode, provided that an appropriate gas diffusion layer prevents water leakage through
theceramic
ceramicseparator.
separator.Furthermore,
Furthermore,using
usingbiotic
biotic cathodes
cathodes that
that utilize microorganisms as as a
biocatalyst for
a biocatalyst forORR
ORRcan canimprove
improvethe thepower
powerperformance
performanceofofMFCsMFCs and
and simultaneously
simultaneously
eliminatemany
eliminate manytoxic
toxicpollutants.
pollutants. Work
Work has been
been carried
carriedout
outononaerobic
aerobiccathodes to enhance
cathodes to en-
the treatment quality. By entering the anodic effluent into the cathode chamber,
hance the treatment quality. By entering the anodic effluent into the cathode chamber, researchers
were able were
researchers to improve
able tothe efficiency
improve of the system
the efficiency [42,43].
of the system [42,43].

Figure 6. Mechanism
Figure of of
6. Mechanism oxygen reduction
oxygen reaction
reduction [44].
reaction [44].

Oxygen
Oxygen Reduction
Reduction Reaction
Reaction
In ORR, various
In ORR, various oxidants oxidantscancanbebeused
usedasaselectron
electronacceptors
acceptors in
in the
the aqueous
aqueous cathodes
cathodes of
of microbial
microbial fuel
fuel cells.
cells. Oxygen
Oxygen is is the
the ideal
ideal electron
electron acceptor
acceptor for
for cathode
cathode electrodes
electrodes since
since it
it is
is readily
readily available
available and
andcheap.
cheap.ORR,
ORR,whichwhichreduces
reducesoxygen
oxygenmolecules
moleculesbyby taking
takingupup electrons
elec-
from
trons the the
from electrode, is the
electrode, is primary
the primaryreaction in aninMFC
reaction cathode
an MFC [45].[45].
cathode
Several electron transfer pathways are involved
Several electron transfer pathways are involved in ORR, and theyin ORR, and they
areare contingent
contingent onon
the kind of catalyst employed at the cathode. Oxygen can be electro-reduced
the kind of catalyst employed at the cathode. Oxygen can be electro-reduced in two main in two main
approaches:
approaches: thesethese are 2-electron
are the the 2-electron
pathwaypathway
and the and the 4-electron
4-electron pathwaypathway
(shown in (shown
Figure in
Figure 6) [46]. Since a large overpotential of hydrogen peroxide can
6) [46]. Since a large overpotential of hydrogen peroxide can occur in the development occur in the develop-
of
ment of 2-electron paths, 4-electron paths are preferable. To evaluate the
2-electron paths, 4-electron paths are preferable. To evaluate the rate-determining step of rate-determining
thestep of the
ORR, ORR,
verify theverify
initialthe initial adsorption
adsorption of oxygenofatoxygen at the electrode
the electrode catalyst’s catalyst’s interface
interface and its
and its subsequent reduction to hydrogen peroxide and water.
subsequent reduction to hydrogen peroxide and water. Depending on the kind of carbonDepending on the kind
of carbon
utilized, there utilized,
are two there
differentare ways
two different ways inreduction
in which oxygen which oxygen reduction
on carbon on takes
materials carbon
materials takes place in the context of non-Pt catalysts in electrolytic ORR. For example,
place in the context of non-Pt catalysts in electrolytic ORR. For example, a proposed mech-
a proposed mechanism describes the reduction of oxygen on an electrode constructed of
anism describes the reduction of oxygen on an electrode constructed of glassy carbon [40],
glassy carbon [40], using the equations shown in (6)–(13),
using the equations shown in (6)–(13),
4-electron electro reduction of oxygen pathway,
4-electron electro reduction of oxygen pathway,
OO22 ++ 4H+
4e−−→→2H
4H+ ++4e 2H 2O
2O (6)(6)
2-electron electro
2-electron reduction
electro ofof
reduction oxygen pathway:
oxygen pathway:
O2 + 2H+ + 2e− → H2O2 (7)
O2 + 2H+ + 2e− → H2 O2 (7)

O22 →
O → O(aq)
O (aq) (8)(8)

O2 (aq) + e− → [O2 (aq)]− (9)

[O2 (aq)]− → O-O2 (aq) (10)
O-O2 (aq) + H2 O → HO2 (aq) + OH− (11)
Water 2024, 16, 1597 8 of 21

HO2 (aq) + e− → HO−2 (aq) (12)

−2 −2
HO (aq) → HO (13)

4. Membrane
To ensure the proper functioning of microbial fuel cells, it is important to use a
membrane to separate the anode and cathode reactions [47]. This membrane allows protons
to move from the anode to the cathode while acting as a physical barrier between the two
chambers and preventing the flow of oxygen from the cathode to the anaerobic anode
chamber. MFC separators or membranes are typically made of polymers and ceramics
and must possess specific characteristics [48], such as strong ionic conductivity, enduring
stability over the long term, high proton conductivity, efficient mass transfer between the
anaerobic anode and the oxygen-containing water in the cathode, low internal resistance,
and good energy recovery [49].
There are several types of ion exchange membranes (IEMs), such as polymeric and
ceramic membranes which allow interchange of both cations as well as anions [50]. These
membranes selectively allow ions with opposing charges to pass through while stopping
ions with similar charges. The five categories of IEMs are cation exchange membranes
(CEM), bipolar membranes (BPM), anion exchange membranes (AEM) [51], mosaic IEMs,
and amphoteric IEMs [52]. Protons and other cations can pass through a membrane and
enter the cathode chamber via CEMs, which are sometimes referred to as PEMs. These
create an overall negative group of functions on the membrane. Conversely, anion exchange
membranes have positive charges such as carbonate or phosphate attached to facilitate
proton transfer using proton carriers [45,53].

4.1. Types of Earthen Membrane

Continuous advancements are being made in the investigation of various types of
ceramic membranes for use in microbial fuel cells. While ceramic membranes are currently
preferred due to their superior mechanical strength, chemical resistance, and suitability for
harsh MFC environments, earthen membranes offer a potentially attractive alternative.
Earthen membranes, composed of naturally occurring clays or earthen materials,
boast significant advantages in terms of sustainability and affordability compared to com-
mercially produced ceramic membranes. However, research on earthen membranes has
fluctuated, likely due to concerns about their limitations, shown in Table 1. These limita-
tions include lower mechanical strength, making them more susceptible to cracking, and
potentially insufficient chemical resistance for the complex MFC environment [54].

Table 1. Comparison of ceramic membrane properties.

Property Earthen Membrane Clayware Membrane Ceramic Membrane Reference

Composition Natural materials (soil, sand, clay) Fired clay Inorganic materials [55–57]
Mechanical Strength Moderate Improved Excellent [56,57]
Chemical Resistance Limited Moderate Excellent [57,58]
Cost Low Moderate High [57]
Availability Abundant Widely available Widely available [55,57]
Eco-friendliness Yes Moderate Moderate [59,60]
Ion Conductivity Moderate Good Excellent [55,57]
Stability Limited Moderate Excellent [57]
Moisture Retention Moderate Moderate Moderate [57]
Lifespan Short Moderate Long [61]
Maintenance Low Low Low [62]
Uniformity Variable Moderate High [55,63]
Pore Size Control Limited Limited Excellent [55,64]
Performance Variable Good Excellent [65,66]
Water 2024, 16, 1597 9 of 21

Despite these challenges, recent research suggests a renewed interest in earthen mem-
branes for MFCs. This resurgence can be attributed to two key trends. Firstly, the growing
emphasis on sustainable practices has encouraged the exploration of eco-friendly materials
like natural clays for MFC applications. Secondly, the inherent affordability of earthen
materials offers a significant economic advantage compared to ceramic membranes [23,67].
Further research and development efforts focused on exploring diverse earthen ma-
terials and developing earthen composite membranes with enhanced properties could
unlock the full potential of this technology. By addressing the current limitations through
targeted material science advancements, earthen membranes can evolve into a viable and
sustainable alternative for MFC separator membranes. This would not only contribute to a
more eco-friendly approach to MFC technology but also offer a cost-effective solution for
wastewater treatment and electricity generation [68].

4.1.1. Earthen Membranes

Earthenware membranes made of natural clay or mud have been a reliable choice
for a long time due to their easy availability and handling. They provide a sustainable
and cost-effective option for construction, making them stand out from traditional mate-
rials. However, sand membranes, despite being overlooked, hold promise for potential
improvements in microbial fuel cell applications. Although they are not as mechanically
and chemically stable as engineered ceramics, their intrinsic porosity presents opportunities
for facilitating ion exchange and mass transfer within MFC systems.
The use of sand membranes in such contexts is still in the early stages of exploration
and needs to be investigated further and optimized (Table 1). A comprehensive review of
literature, covering soil-based materials and ancient pottery, can yield valuable insights
into the properties of these materials and their suitability for diverse applications. Despite
the limited discussion regarding earthen membranes in MFCs, their potential justifies
careful consideration and systematic study for future advancements in sustainable energy
technologies [69–72].

4.1.2. Clayware Membranes

Clay, a type of soil rich in minerals and organic matter, has been used for pottery
and construction for centuries. In MFCs, clay-based membranes are emerging as a cost-
effective and environmentally friendly option (Table 1). Clay’s natural porosity and ion
exchange capabilities make it ideal for crafting membranes tailored to MFCs. Its unique
adsorption properties and sustainability make it a compelling alternative to traditional
membranes. During manufacturing, clay can be shaped into a thin, porous layer that acts
as a selective barrier. This membrane allows ions to pass through while blocking larger
organic molecules. Optimizing this design could improve MFCs’ electrochemical processes,
boosting their efficiency and performance overall [73–75].

4.1.3. Ceramic Membranes

Ceramic materials have played pivotal roles in the progress of civilizations, appearing
independently across diverse cultures to create similar objects. The production of “earthen-
ware”, characterized by its solid yet brittle structure, involves a process of extracting clay,
mixing it with water, shaping it, sun-drying it, and finally, firing it in a kiln [76].
Ceramic membranes represent advanced materials with applications spanning separa-
tion, filtration, and purification in various industrial processes. Set apart from conventional
polymeric membranes, as shown in Table 1, ceramic membranes are composed of inorganic
materials such as alumina, zirconia, and more [77]. A robust substrate supports a thin,
porous layer crucial to the formation of ceramic membranes, wherein the filtration or
separation process predominantly occurs.
Ceramics excel in demanding sectors like food and beverage, biotechnology, phar-
maceuticals, and water treatment due to their remarkable attributes, including chemical
stability, mechanical strength, and resistance to high temperatures [78]. Notably, ceramic
Water 2024, 16, 1597 10 of 21

membranes exhibit superior tolerance to corrosive chemical conditions, ensuring prolonged

functionality even in harsh environments compared to polymer membranes [79]. This
durability translates into extended lifespans and reduced maintenance requirements.
Moreover, ceramic membranes thrive in processes involving elevated temperatures,
thanks to their exceptional thermal stability [80]. This feature proves particularly beneficial
in applications like wastewater treatment, where higher temperatures enhance separation
efficiency or facilitate the efficient treatment of certain toxins. Another significant advantage
lies in the precise control of pore size offered by ceramic membranes. Manufacturers
can tailor pore diameters to meet the specific separation needs of diverse applications,
enhancing their adaptability and utility across various industrial processes [81].
Ceramic membranes are used in water treatment to filter and cleanse water and
wastewater. They can eliminate particles, germs, and even viruses thanks to precisely cali-
brated porosity, ensuring that the water that is treated satisfies strict quality requirements.
Additionally, the dairy and beverage sectors are using ceramic membranes more frequently
to clarify and concentrate liquids [82].
Since ceramic membranes are so good at providing sterile filtration, their use in biotech
and medical fields is growing. These membranes’ durability makes it possible to undergo
thorough cleaning and sterilizing operations, which are essential for preserving the integrity
of delicate biological procedures [79,80]. Ceramic membranes have many benefits, but they
also have certain drawbacks. Compared to other polymer membranes, they are often more
expensive to produce and need a more involved manufacturing procedure. Continued
research and developments in manufacturing techniques aim to overcome these obstacles
and increase the affordability and accessibility of ceramic membranes [79,83].
However, earthen membranes may have lower mechanical strength compared to
their engineered counterparts, making them less robust and more susceptible to deforma-
tion. Clayware membranes, specifically processed to enhance mechanical strength, offer
improved durability compared to earthen membranes. Ceramic membranes, with their
inorganic composition and specialized manufacturing processes, boast the highest mechan-
ical strength and durability among the three types. In terms of performance, clayware
membranes may have porosity levels several times higher than earthen membranes, while
ceramic membranes typically exhibit even higher porosity levels compared to both earthen
and clayware membranes. Overall, while earthen membranes provide a cost-effective and
accessible option for certain applications, clayware and ceramic membranes offer superior
performance and durability, making them more suitable for demanding industrial processes
and long-term use.

5. Ion Transport across Membranes and Its Characterization

Different analytical approaches listed in the available research, including proton
transport, ion transport, oxygen transport, water uptake, and change in conductivity, were
used to determine the transport of ions through the membranes [84]. The next paragraphs
provide a summary of each technique’s inclusive description.

5.1. Mass Transport of Oxygen

The oxygen mass transfer coefficient in MFCs indicates whether the membranes can let
or prevent oxygen from penetrating. Membranes play a critical role in preventing oxygen
from diffusing from the cathode into the anode chamber. With an easily carried dissolved
oxygen (DO ) probe, the oxygen coefficient for mass transfer may be established [85]. The
DO mass balance in the chamber is determined in a two-chamber system with total mixing
and membrane-assisted chamber separation.

V da/dt = fO A = DO A/Lt (xo − x) (14)

In the given expression, V is the chamber volume in liters; fo is the oxygen flux
measured in (kg−3 /ms); A is the membrane area in (m−4 ); Lt is the membrane thickness in
(m−2 ) as provided by the manufacturer; Do is the diffusion coefficient expressed in (m−4 /s);
Water 2024, 16, 1597 11 of 21

xo is the saturating the oxygen concentration that exists in the aerated chamber measured
in (kg−3 /L); and x is the dissolved oxygen (DO ) concentration in the anode chamber at a
given time (t). This formulates the connection as follows:

Do = −VLt /At ln (xo − x/xo ) (15)

The oxygen mass transfer coefficient (Ko) and diffusion coefficient (Do) in a two-
chamber MFC system [51] may be calculated using the previously given formula,

Ko = −V/At ln (xo − x/xo ) (16)

where Ko is (m/s).

5.2. Mass Transport of Proton

A dual-chamber system was employed in the experimental setting; the first chamber
had pH-controlled deionized water, and the second chamber held a solution with a different
pH. The systematic monitoring of pH variations at regular times in both chambers was
carried out using two pH electrodes. This analytical methodology made it possible to assess
the kinetics of proton transport across the membrane accurately. Using Equation (14),

KH = −V/2At × ln(Ca + Cc − 2Cp /Ca ) (17)

A two-chamber system’s essential parameters are outlined in the formula that is

provided: the liquid volume in the anode chamber (V) is shown in (m−6) , the projected
membrane surface area (A) is expressed in (m−4 ), time (t) is expressed in (s), and the starting
proton concentrations in the anodic and cathodic chambers are represented by Ca and Cc ,
respectively. The proton concentration in the cathode chamber at time t is represented by
Cp . The equation is also used to calculate the proton diffusion coefficient (DH , m−4 /s),
where Lth is the membrane thickness (m−2 ) and KH is the proton mass transfer coefficient
(m−2 /s) found in the previous calculation, as shown in Equation (15):

DH = KH × Lth (18)

This formulation has a key component in the comprehension and measurement of the
dynamics of proton mass transfer in MFC devices [86].

5.3. Water Uptake

The water absorption capacity of membrane is assessed by putting it in demineralized
water at 303 K for 24 h, allowing it to swell. Its weight, considering surface water removal,
is then measured. Then, the membrane is dried for 15 h at 303 K, and its dry weight is
recorded before immersing it in deionized water [87]. Using the following formula, the
water uptake capacity is given as a percentage:

Water uptake capacity (%) = [(weight of expand membrane − weight of

(19)
dried membrane)/weight of dried membrane] × 100

5.4. Ion Exchange Capacity

The ion exchange capacity (IEC) of a membrane shows whether charged it is as an
outcome of its various functional groups. It represents the ions that are obtainable for
exchange across the membrane and acts as a measure for the density of current [88]. A
technique called back titration can be used to measure the IEC of membranes. This means
presenting the IEC as the membrane sample’s entire charge divided by dry weight [51].

IEC = total charge/dry weight (20)

where the dry weight unit is grams (g).

Water 2024, 16, 1597 12 of 21

6. Results and Discussion

As shown in Table 2, ceramic membrane configurations with a stainless-steel electrode
in a dual chamber system proved to be the most efficient way to attain the maximum
CD of 1422.22 ± 41.2 mW/m2 and PD of 229.12 ± 18.5 mW/m2 . The increased electron
transfer kinetics were responsible for the membrane’s observed KO rate of 9.1 × 10−5
and KH rate of (222.73 ± 22.7) × 10−3 . This configuration is ideal for the treatment of
domestic wastewater [89]. Secondly, CHI/MMT nanocomposites in a ceramic membrane
displayed outstanding COD removal of 95.67%. The PD value of 119.58 ± 19.16 mW/m2
and CD value of 869.44 ± 27.49 mW/m2 were the greatest measured. These outcomes
were found to be effectively achieved by both the modification of the nanocomposite and
the usage of carbon cloth electrodes. Treatment of raw wastewater may be accomplished
using this setup, which has a KO rate of 0.83 × 10−4 [90]. It was discovered that a bentonite
clay-modified membrane worked well in a dual chamber for treating sewage. Effective
electron transfer was made possible by the 60-day operation, which produced an acceptable
PD of 15.38 mW/m3 and a CD of 38.46 mW/m2 [91]. In the other method using graphite
fiber as both the anode and cathode material, a ceramic membrane designed for sanitary
sewage treatment attained a CD of 103 ± 7 mW/m2 and a PD of 261 mW/m2 . This system
was shown to be successful when it was operated for an extended period of 210 days,
treating mixed swine waste with a hydraulic retention time of 4 h [92]. A mixed inoculum
in a ceramic anaerobic treatment plant had the greatest COD removal rate of 96.6%. This
arrangement is suitable for anaerobic treatment operations since it produced the maximum
current density of 1535.0 ± 29 mW/m2 when carbon brush electrodes and a dual chamber
were used [93]. The table presents a unique ceramic membrane combination that utilizes a
dual-chamber layout of clay materials and a SUPER-MIX inoculum. A rate of 2.5 × 10−5
oxygen transport was achieved with this arrangement. With a high power of 275 mW/m2
attained, the COD removal was 91 ± 3.96%. Effective electron transfer and removal
of pollutants were made possible by the SUPER-MIX inoculum, carbon-felt electrodes,
and dual-chamber construction [94]. This used a ceramic membrane made for treating
effluent from rice mills, comprising a dual-chamber structure using soil with 30% silica
and 20% w/w bentonite clay. The system achieved a KO rate of 11.35 × 10−4 mW/m2
and a KH rate of 3.64 × 10−5 mW/m2 . Effective electron transfer was facilitated using
graphite plates and stainless-steel electrodes, and the system’s COD removal of 71.3% was
evidence of its success [95]. A two-chamber setup used Kalporgan soil in different SiO2
concentrations (0–30%) with carbon brushes and carbon clothes as electrodes, and reached
a 769.23 mW/m2 current density. This setup effectively removed pollutants and showed a
significant 85% reduction of COD [66]. This arrangement had a dual-chamber structure
with stainless-steel electrodes and graphite plate, and used red soil that contained 20%
bentonite. It accomplished a 52% elimination of COD, a KH rate of 6.55 × 10−6 mW/m2 ,
and a KO rate of 9.33 × 10−4 mW/m2 . Red soil treated with bentonite improved pollution
removal and electron transfer rates [96].
Water 2024, 16, 1597 13 of 21

Table 2. Overview of based on ceramic membrane MFC.

Operation Current Power COD

Waste-Water Oxygen Mass Proton Mass
Membrane Modification Setup Inoculum Anode Cathode Time Density Density Removal Ref.
Treatment Transfer Transfer
(day) (mW/m2 ) (mW/m2 ) (%)
Anaerobic
Carbon Carbon
Clayware Sewage Bentonite clay Dual chamber microbial 60 - - 38.46 15.38 - [91]
fiber fiber
culture
Raw Carbon Carbon
Ceramic Domestic CHI/MMT Dual chamber - 0.83 × 10−4 - 869.44 ± 27.49 119.58 ± 19.16 95.67 [90]
wastewater cloth cloth
Carbon Stainless (222.73 ± 22.7)
Ceramic Domestic CHI/MMT Dual chamber - 10 9.1 × 10−5 1422.22 ± 41.2 229.12 ± 18.5 87 [89]
cloth steel × 10−3
Sanitary Single Mixed Graphite Graphite
Ceramic - 210 - - 103 ± 7 261 - [97]
sewer chamber swine waste fiber fiber
KS, LKS, and
Anaerobic Carbon Carbon
Ceramic Domestic CCP mixed Dual chamber - - - 1535.0 ± 29 20.18 ± 0.83 96.6 [98]
wastewater brush cloths
with tap water
Clay (1%, 2%,
5% and 10%) Anaerobic
Clayware Synthetic Dual chamber Carbon felt Carbon felt - 1.3 × 10−4 9 × 10−5 779 - 81.05 ± 0.08 [99]
mixed with sludge
ACCS
Soil with 20% Anaerobic Stainless- Graphite
Ceramic Rice mill Dual chamber 14 1.31 × 10−5 - - 80.15 70.7 ± 1.24 [100]
bentonite clay sludge steel plates
Anaerobic
Montmorillonite (4.02 ± 0.38)
Clayware Synthetic Dual chamber mixed Carbon felt Carbon felt 3 17.9 × 10−3 - 83.5 88 [101]
20% clay × 10−5
sludge
Anaerobic
Graphite Graphite
Earthen Synthetic Goethite (G-5) Dual chamber mixed 3 1.95 × 10−5 78.71 × 10−3 - 112.81 ± 8.74 22 [102]
felt felt
sludge
Red soil with
Single (4.01 ± 0.02) (8.84 ± 0.11)
Earthen Synthetic MMT (20%) + 1% sludge Carbon felt Carbon felt 30 168 162.74 80.48 ± 0 [67]
chamber ×10−5 × 10−3
VC (20%)
Municipal
Pharma Graphite Graphite
Earthen - Dual chamber solid - - - - - 80.55 [103]
industry material material
wastewater
20% montmo-
Single
Ceramic Sanitary rillonite Sewage Carbon felt Carbon felt 255 - - - - 87.29 ± 7.28 [104]
chamber
blended
Water 2024, 16, 1597 14 of 21

Table 2. Cont.

Operation Current Power COD

Waste-Water Oxygen Mass Proton Mass
Membrane Modification Setup Inoculum Anode Cathode Time Density Density Removal Ref.
Treatment Transfer Transfer
(day) (mW/m2 ) (mW/m2 ) (%)
Rock
phosphate
Single Cow Graphite Graphite
Clayware Synthetic mixed with - - 5.34 × 10−6 - - 74.4 ± 4 [92]
chamber manure felt felt
black soil
(5–10%)
Soil mixed
with kaolin
Pond Stainless Graphite
Ceramic Synthetic (10%, 20%, Dual chamber 60 - 8.18 × 10−6 - - 93.1 [93]
sludge steel plates
30%, 40%
and 50%)
SUPER-
Ceramic Synthetic Clay samples Dual chamber Carbon felt Carbon felt 11 2.5 × 10−5 - - 275 91 ± 3.96 [94]
MIX
Starch- Mixed
Graphite Graphite
Clayware Sanitary kaolinite clay Dual chamber microbial - - - - 82.4 - [105]
rod rod
mixture consortium
Soil with 20%
w/w Anaerobic Stainless Graphite
Ceramic Rice mill Dual chamber 40 11.35 × 10−4 3.64 × 10−5 - 71.3 76.24 [95]
bentonite clay sludge steel plate
and silica 30%
Activated
sludge
(40%) white
Activated Single (75%) and
Ceramic and (30%) Carbon veil Carbon veil 90 - - - 81 98.2 [60]
sludge chamber mineral salt
gray ceramic
medium
(25%)
Suspension of Single Sewage
Clayware Synthetic Carbon felt Carbon felt 250 - - 172 11.2 - [106]
clay (20–30%) chamber sludge
Kalporgan
Carbon Carbon
Earthen Domestic Soil and SiO2 Dual chamber Wastewater - - - 769.23 - 85.8 [66]
brush cloths
(0–30%)
Graphite Graphite
Earthen Synthetic Dual chamber 49 - - 544.6 - 94 ± 2.87 [107]
rod rod
Kitchen
Red soil with waste slurry Stainless Graphite
Earthen Kitchen Dual chamber 11 9.33 × 10−4 6.55 × 10−6 52 - 98.41 [96]
bentonite 20% and steel plate
leachate
Water 2024, 16, 1597 15 of 21

6.1. Water Uptake Capacity

The water uptake capacity of microbial fuel cell separators is a crucial factor that
affects their performance by facilitating proton transportation. Protons are generated
as byproducts of microbial respiration, and they rely on cooperative OH covalent and
hydrogen bonding dynamics to navigate through the membrane toward the cathode via
the Grotthuss mechanism. This mechanism involves protons moving along water chains
formed by hydrogen bonding, where initially, a proton interacts with a water molecule’s
oxygen, creating a hydrogen bond, and then transitioning into an OH covalent bond. This
process enables proton transfer along the water chain until the terminal water molecules
release the proton, thus completing the conduction process [108].
The water uptake capacity of various membranes significantly impacts their ability to
facilitate proton transportation. According to Das et al. 2020, the G-5 membrane has an
18% water uptake, which is due to the hydrophilic nature of goethite within its matrix, and
this increases its efficiency [102]. On the other hand, Nafion membranes, known for their
high water uptake (32%), demonstrate superior proton transport capabilities. Similarly,
clay separators, with a 13% water uptake, contribute to proton transportation, albeit less
efficiently compared to Nafion [12].
In addition, membranes with high water-holding capacities, such as the SMN mem-
brane, show improved performance compared to counterparts like the SM membrane.
Notably, the Nafion-117 membrane has the highest water-holding capacity among all
membranes, which further enhances its proton transport capabilities [67].
In the context of ceramic membranes, which rely on pores for ion passage, water uptake
is critical. Reports suggest that reducing silicone content in ceramic membranes enhances
water absorption, resulting in a 64% improvement in power output due to heightened
ionic conductivity and diminished ohmic resistance [61]. Furthermore, the swelling ratio of
membranes, which is influenced by additives like ACCS, also affects water uptake. While
higher ACCS content initially increases swelling ratios, further augmentation beyond
5% ACCS fails to correspondingly enhance water uptake due to reduced pore volume.
Therefore, membranes are cast with 5% ACCS based on preliminary studies to optimize
both water uptake and overall performance [99].

6.2. Ion Exchange Capacity

The ion exchange capacity of a membrane is closely linked to its water retention
ability. Usually, the higher the water retention capacity of a membrane, the higher its
IEC. This happens because water helps in the exchange of ions, making it easier for the
membrane to transport a larger number of ions. In addition, water retention is critical for
the transportation of protons through membranes. Protons, produced in the anolyte due to
bacterial activity, are moved with water through the membrane to the cathode. Essentially,
membranes that can hold more water enable the transfer of a larger number of protons.
To sum up, the higher the water retention capacity of a membrane, the higher the proton
diffusion and water uptake.

6.3. Power Density

Gurjar and Behera conducted a study that showed a significant difference in power
density between leachate and kitchen waste slurry treatments. Leachate exhibited a
20-fold higher power density compared to KW slurry treatments. The increase in substrate
concentration positively influenced power density, which is consistent with observations
from leachate treated MFC systems. However, the MFC subjected to higher organic loads
(LW-5) showed a 35% decrease in power density compared to LW-4. This decrease was
attributed to alternative metabolic pathways compromising exoelectrogen growth in the
batch operation mode of the EMFC [96,109].
Gunaseelan et al. achieved a remarkable power density of 275 mW/m2 using SUPER-
MIX BPVs with a ceramic separator, which is comparable or superior to BPVs with hetero-
genic APBs and Nafion separators. This is contrary to previous studies that used mixed
Water 2024, 16, 1597 16 of 21

anoxygenic photosynthetic bacteria (APBs) and a Nafion-117 membrane [94]. Raychaud-

huri et al. compared separators containing 0% and 30% silica, achieving a maximum power
density of 98.7 mW/m2 when operated with real rice mill wastewater (Table 2) [95].
Obasi et al. reported a maximum power density of 82.4 mW/m2 under optimized con-
ditions. Cheraghipoor et al. observed a doubling of power density compared to the Nafion
membrane by leaching Kalporgan soil to enhance ceramic membrane conductivity [105].
Sarma and Mohanty noted significant improvements in power density and current density
with acid-treated carbon fiber modification [91].
Pasternak et al. [60] reported superior power performance with ceramic materials,
particularly earthenware and pyrophyllite with higher SiO2 content. Neethu et al. achieved
a remarkable maximum power density of 3.7 W/m3 with MFC-ACCS/Clay, nearly twice
that obtained using a Nafion 117 membrane [99]. Lastly, Bagchi and Behera [97] reported a
maximum power density of 142 mW/m2 from a reactor with a separator containing 20%
montmorillonite, which is comparable to the highest power generated in the current study
at 100 mW/m2 .

6.4. COD Removal

The provided dataset contains studies that assessed the effectiveness of microbial fuel
cells in wastewater treatment by measuring COD removal efficiency. The range of COD
removal percentages across these studies indicates a spectrum of treatment outcomes. The
study conducted by Sarma and Mohanty reported the highest COD removal percentage of
98.41%, which is significantly higher than the values reported in other studies, such as the
96.6% COD removal efficiency reported by Cheraghipoor et al. and the 95.67% achieved
by Yousefi et al. The disparities between these figures become apparent upon closer
examination, with Sarma and Mohanty’s efficiency being approximately 1.81 and 2.03 times
higher than that of Cheraghipoor et al. and Yousefi et al., respectively. This comparison
highlights the need to refine operational parameters in MFC systems to maximize treatment
efficiency and underscores the potential for further advancements in wastewater treatment
technologies through targeted research and development endeavors.

6.5. Coulombic Efficiency

Analyses of Coulombic efficiency in MFCs across various studies have revealed notable
differences influenced by operational parameters, electrode configurations, and membrane
materials. For instance, in the study by Cheraghipoor et al., a significant increase in CE,
from 53% to 83%, was observed when shifting from an MFC using a Nafion membrane to
one employing a ceramic membrane derived from leached soil [98]. Similarly, investigations
conducted by Das et al. showed higher CE values for specific MFC setups, with MFC-B
achieving a CE of 10.2 ± 1.3%, representing a 34% improvement compared to MFC-N
(7.6 ± 1.0%) and a 70% enhancement relative to MFC-A (6.0 ± 1.0%) [101]. This trend
persisted in studies like that of Das et al., where MFC-G5 exhibited the highest average
CE of 23.74 ± 2.14%, surpassing MFC-N and MFC-C by approximately fivefold and 8.6%,
respectively [102]. Furthermore, findings from Obasi et al. showcased a CE of 15 ± 7.5% in
an MFC operating under a 3 Ω external load [105].

7. Conclusions and Future Perspectives

Ceramics is a cost-effective material that works similarly to conventional membranes
in wastewater treatment using microbial fuel cells. It can be used as a separator in MFCs
because it carries both protons and ions. This review focused on how clayware, earthen,
and ceramic membrane systems perform in MFCs for the treatment of wastewater and
sustainable energy.
Various ceramic membranes are extensively studied for their role as separators in
MFCs. Their properties, such as porosity, proton exchange, and electrical conductivity, have
a significant impact on membrane performance. Compared to other materials, ceramic
membranes have been found to exhibit superior outcomes in power density, current density,
Water 2024, 16, 1597 17 of 21

and COD removal. Materials such as red soil, Kalporgan soil, CHI/MMT nanocomposites,
and bentonite clay have shown adaptability and long-term efficacy in treating diverse
wastewaters. However, to optimize electron transfer dynamics and MFC efficiency, modi-
fications like double-chamber setups, tailored inoculums, and specific electrode material
selection are required. Despite complexities, ceramic-based membranes show promise
in enhancing MFC efficiency, underlining their significance in wastewater treatment and
sustainable energy generation.
Moreover, the properties of anode and cathode materials play a crucial role in MFC
efficiency, with ceramic-based membranes showing significant promise in improving over-
all performance. When considering the cost of MFCs, dual-chamber configurations tend
to be more costly than their single-chamber alternative. The membrane components con-
tribute up to 60% of the overall cost of the MFCs. Therefore, it is important to explore
single-chamber setups that use cost-effective ceramic-based membranes to improve the
performance of the membrane. While this technology holds great promise, further study is
required before its commercialization.

Author Contributions: Conceptualization, A.T., D.A.J. and N.Y.; validation, A.T., N.Y., D.A.J. and
K.A.; formal analysis, A.T. and D.A.J.; investigation, N.Y., D.S. and K.A.; resources, N.Y. and D.S.; data
curation, A.T., D.A.J. and N.Y.; writing—review and editing, N.Y., V.K.S., S.S. and K.A.; visualization,
D.S. and N.Y.; supervision, A.T. All authors have read and agreed to the published version of
the manuscript.
Funding: This research received no external funding.
Data Availability Statement: No new data were created or analyzed in this study. Data sharing is
not applicable to this article.
Conflicts of Interest: The authors declare no conflicts of interest.

References
1. Verma, P.; Daverey, A.; Arunachalam, K. Development and characterization of novel low-cost engineered pine needle biochar and
montmorillonite clay based proton exchange membrane for microbial fuel cell. J. Water Process. Eng. 2023, 53, 103750. [CrossRef]
2. Kusmayadi, A.; Leong, Y.K.; Yen, H.W.; Huang, C.Y.; Dong, C.D.; Chang, J. Microalgae-microbial fuel cell (mMFC): An integrated
process for electricity generation, wastewater treatment, CO2 sequestration and biomass production. Int. J. Energy Res. 2020,
19, 44. [CrossRef]
3. Rahimnejad, M.; Adhami, A.; Darvari, S.; Zirepour, A.; Oh, S.-E. Microbial fuel cell as new technology for bioelectricity generation:
A review. Alex. Eng. J. 2015, 54, 745–756. [CrossRef]
4. Jiang, Y.; Yang, X.; Liang, P.; Liu, P.; Huang, X. Microbial fuel cell sensors for water quality early warning systems: Fundamentals,
signal resolution, optimization and future challenges. Renew. Sustain. Energy Rev. 2018, 81, 292–305. [CrossRef]
5. Kannan, M.; Kumar, G.G. Current status, key challenges and its solutions in the design and development of graphene based ORR
catalysts for the microbial fuel cell applications. Biosens. Bioelectron. 2016, 77, 1208–1220. [CrossRef]
6. Ghasemi, M.; Ismail, M.; Kamarudin, S.K.; Saeedfar, K.; Daud, W.R.W.; Hassan, S.H.; Heng, L.Y.; Alam, J.; Oh, S.-E. Carbon
nanotube as an alternative cathode support and catalyst for microbial fuel cells. Appl. Energy 2013, 102, 1050–1056. [CrossRef]
7. Ahn, Y.; Logan, B.E. Effectiveness of domestic wastewater treatment using microbial fuel cells at ambient and mesophilic
temperatures. Bioresour. Technol. 2010, 101, 469–475. [CrossRef]
8. Muga, H.E.; Mihelcic, J.R. Sustainability of wastewater treatment technologies. J. Environ. Manag. 2008, 88, 437–447. [CrossRef]
9. Rahimnejad, M.; Bakeri, G.; Ghasemi, M.; Zirepour, A. A review on the role of proton exchange membrane on the performance of
microbial fuel cell. Polym. Adv. Technol. 2014, 25, 1426–1432. [CrossRef]
10. Li, W.-W.; Sheng, G.-P.; Liu, X.-W.; Yu, H.-Q. Recent advances in the separators for microbial fuel cells. Bioresour. Technol. 2011,
102, 244–252. [CrossRef]
11. Yaqoob, A.A.; Ibrahim, M.N.M.; Rodríguez-Couto, S. Development and modification of materials to build cost-effective anodes
for microbial fuel cells (MFCs): An overview. Biochem. Eng. J. 2020, 164, 107779. [CrossRef]
12. Tiwari, B.; Noori, M.; Ghangrekar, M. A novel low cost polyvinyl alcohol-Nafion-borosilicate membrane separator for microbial
fuel cell. Mater. Chem. Phys. 2016, 182, 86–93. [CrossRef]
13. Leong, J.X.; Daud, W.R.W.; Ghasemi, M.; Ben Liew, K.; Ismail, M. Ion exchange membranes as separators in microbial fuel cells
for bioenergy conversion: A comprehensive review. Renew. Sustain. Energy Rev. 2013, 28, 575–587. [CrossRef]
14. Ieropoulos, I.; Theodosiou, P.; Taylor, B.; Greenman, J.; Melhuish, C. Gelatin as a promising printable feedstock for microbial fuel
cells (MFC). Int. J. Hydrogen Energy 2017, 42, 1783–1790. [CrossRef]
Water 2024, 16, 1597 18 of 21

15. Chandrasekhar, K.; Kumar, A.N.; Kumar, G.; Kim, D.-H.; Song, Y.-C.; Kim, S.-H. Electro-fermentation for biofuels and biochemicals
production: Current status and future directions. Bioresour. Technol. 2020, 323, 124598. [CrossRef]
16. Do, M.; Ngo, H.; Guo, W.; Liu, Y.; Chang, S.; Nguyen, D.; Nghiem, L.; Ni, B. Challenges in the application of microbial fuel cells to
wastewater treatment and energy production: A mini review. Sci. Total Environ. 2018, 639, 910–920. [CrossRef]
17. Roy, H.; Rahman, T.U.; Tasnim, N.; Arju, J.; Rafid, M.; Islam, R.; Pervez, N.; Cai, Y.; Naddeo, V.; Islam, S. Microbial Fuel Cell
Construction Features and Application for Sustainable Wastewater Treatment. Membranes 2023, 13, 490. [CrossRef]
18. Obileke, K.; Onyeaka, H.; Meyer, E.L.; Nwokolo, N. Microbial fuel cells, a renewable energy technology for bio-electricity
generation: A mini-review. Electrochem. Commun. 2021, 125, 107003. [CrossRef]
19. Rinaldi, A.; Mecheri, B.; Garavaglia, V.; Licoccia, S.; Di Nardo, P.; Traversa, E. Engineering materials and biology to boost
performance of microbial fuel cells: A critical review. Energy Environ. Sci. 2008, 1, 417–429. [CrossRef]
20. He, L.; Du, P.; Chen, Y.; Lu, H.; Cheng, X.; Chang, B.; Wang, Z. Advances in microbial fuel cells for wastewater treatment. Renew.
Sustain. Energy Rev. 2017, 71, 388–403. [CrossRef]
21. Flimban, S.G.; Kim, T.; Ismail, I.M.; Oh, S.E. Overview of microbial fuel cell (MFC) recent advancement from fundamentals to
applications: MFC designs, major elements, and scalability. Preprints 2018, 2018100763. [CrossRef]
22. Tamboli, E.; Eswari, J.S. Microbial fuel cell configurations: An overview. In Microbial Electrochemical Technology; Elsevier:
Amsterdam, The Netherlands, 2019; pp. 407–435. [CrossRef]
23. Tiwari, A.K.; Jain, S.; Mungray, A.A.; Mungray, A.K. SnO2 :PANI modified cathode for performance enhancement of air-cathode
microbial fuel cell. J. Environ. Chem. Eng. 2020, 8, 103590. [CrossRef]
24. Das, S.; Mangwani, N. Recent developments in microbial fuel cells: A review. J. Sci. Ind. Res. 2010, 69, 727–731.
25. Yan, X.; Lee, H.-S.; Li, N.; Wang, X. The micro-niche of exoelectrogens influences bioelectricity generation in bioelectrochemical
systems. Renew. Sustain. Energy Rev. 2020, 134, 110184. [CrossRef]
26. Chang, H.; Zhong, N.; Quan, X.; Qi, X.; Zhang, T.; Hu, R.; Sun, Y.; Wang, C. Membrane technologies for sustainable and
eco-friendly microbial energy production. In Membranes for Environmental Applications. Environmental Chemistry for a Sustainable
World; Springer: Cham, Switzerland, 2020; pp. 353–381.
27. Logan, B.E.; 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. [CrossRef] [PubMed]
28. Rabaey, K.; Lissens, G.; Siciliano, S.D.; Verstraete, W. A microbial fuel cell capable of converting glucose to electricity at high rate
and efficiency. Biotechnol. Lett. 2003, 25, 1531–1535. [CrossRef] [PubMed]
29. Cheng, S.; Liu, H.; Logan, B.E. Increased performance of single-chamber microbial fuel cells using an improved cathode structure.
Electrochem. Commun. 2006, 8, 489–494. [CrossRef]
30. Hong, L.; Ramanathan, R.; Logan, B.E. Production of Electricity during Wastewater Treatment Using a Single Chamber Microbial
Fuel Cell. Environ. Sci. Technol. 2004, 38, 2281–2285.
31. Logan, B.E.; Regan, J.M. Microbial Fuel Cells—Challenges and Applications. Environ. Sci. Technol. 2006, 40, 5172–5180. [CrossRef]
32. Wang, H.; Park, J.-D.; Ren, Z.J. Practical Energy Harvesting for Microbial Fuel Cells: A Review. Environ. Sci. Technol. 2015, 49,
3267–3277. [CrossRef]
33. Santoro, C.; Arbizzani, C.; Erable, B.; Ieropoulos, I. Microbial fuel cells: From fundamentals to applications. A review. J. Power
Sources 2017, 356, 225–244. [CrossRef] [PubMed]
34. Yaqoob, A.A.; Ibrahim, M.N.M.; Guerrero-Barajas, C. Modern trend of anodes in microbial fuel cells (MFCs): An overview.
Environ. Technol. Innov. 2021, 23, 101579. [CrossRef]
35. Kaur, R.; Marwaha, A.; Chhabra, V.A.; Kim, K.-H.; Tripathi, S. Recent developments on functional nanomaterial-based electrodes
for microbial fuel cells. Renew. Sustain. Energy Rev. 2020, 119, 109551. [CrossRef]
36. Elshobary, M.E.; Zabed, H.M.; Yun, J.; Zhang, G.; Qi, X. Recent insights into microalgae-assisted microbial fuel cells for generating
sustainable bioelectricity. Int. J. Hydrogen Energy 2021, 46, 3135–3159. [CrossRef]
37. Yousefi, V.; Mohebbi-Kalhori, D.; Samimi, A. Ceramic-based microbial fuel cells (MFCs): A review. Int. J. Hydrogen Energy 2017,
42, 1672–1690. [CrossRef]
38. Lovley, D.R. Electromicrobiology. Annu. Rev. Microbiol. 2012, 66, 391–409. [CrossRef]
39. Bond, D.R.; Lovley, D.R. Electricity Production by Geobacter sulfurreducens Attached to Electrodes. Appl. Environ. Microbiol. 2003,
69, 1548–1555. [CrossRef]
40. Ben Liew, K.; Daud, W.R.W.; Ghasemi, M.; Leong, J.X.; Lim, S.S.; Ismail, M. Non-Pt catalyst as oxygen reduction reaction in
microbial fuel cells: A review. Int. J. Hydrogen Energy 2014, 39, 4870–4883. [CrossRef]
41. Kim, B.H.; Park, H.S.; Kim, H.J.; Kim, G.T.; Chang, I.S.; Lee, J.; Phung, N.T. Enrichment of microbial community generating
electricity using a fuel-cell-type electrochemical cell. Appl. Microbiol. Biotechnol. 2004, 63, 672–681. [CrossRef] [PubMed]
42. 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. [CrossRef]
43. Holmes, D.; Bond, D.; O’neil, R.; Reimers, C.; Tender, L.; Lovley, D. Microbial Communities Associated with Electrodes Harvesting
Electricity from a Variety of Aquatic Sediments. Microb. Ecol. 2004, 48, 178–190. [CrossRef] [PubMed]
44. Ramirez-Nava, J.; Martínez-Castrejón, M.; García-Mesino, R.L.; López-Díaz, J.A.; Talavera-Mendoza, O.; Sarmiento-Villagrana, A.;
Rojano, F.; Hernández-Flores, G. The Implications of Membranes Used as Separators in Microbial Fuel Cells. Membranes 2021,
11, 738. [CrossRef] [PubMed]
Water 2024, 16, 1597 19 of 21

45. Kundu, P.P. Conducting Polymer-Based Microbial Fuel Cells; Materials Research Foundations: Millersville, PA, USA, 2019.
46. Majidi, M.R.; Farahani, F.S.; Hosseini, M.; Ahadzadeh, I. Low-cost nanowired α-MnO2 /C as an ORR catalyst in air-cathode
microbial fuel cell. Bioelectrochemistry 2019, 125, 38–45. [CrossRef] [PubMed]
47. Chen, J.P.; Mou, H.; Wang, L.K.; Matsuura, T.; Wei, Y. Membrane separation: Basics and applications. In Membrane and Desalination
Technologies; Humana Press: Totowa, NJ, USA, 2011; pp. 271–332.
48. Midyurova, B.; Nenov, V. Novel Proton Exchange Membranes and Separators Applied in Microbial Fuel Cells (MFC). J. Balk.
Tribol. Assoc. 2016, 22, 2596–2615.
49. Shabani, M.; Younesi, H.; Pontié, M.; Rahimpour, A.; Rahimnejad, M.; Zinatizadeh, A.A. A critical review on recent proton
exchange membranes applied in microbial fuel cells for renewable energy recovery. J. Clean. Prod. 2020, 264, 121446. [CrossRef]
50. Luo, T.; Abdu, S.; Wessling, M. Selectivity of ion exchange membranes: A review. J. Membr. Sci. 2018, 555, 429–454. [CrossRef]
51. Daud, S.M.; Kim, B.H.; Ghasemi, M.; Daud, W.R.W. Separators used in microbial electrochemical technologies: Current status
and future prospects. Bioresour. Technol. 2015, 195, 170–179. [CrossRef] [PubMed]
52. Strathmann, H. Ion-Exchange Membrane Separation Processes; Pergamon: Middlesex, UK, 2004; pp. 1166–1175.
53. Harnisch, F.; Schröder, U. Selectivity versus Mobility: Separation of Anode and Cathode in Microbial Bioelectrochemical Systems.
ChemSusChem 2009, 2, 921–926. [CrossRef] [PubMed]
54. Jadhav, D.A.; Park, S.-G.; Pandit, S.; Yang, E.; Abdelkareem, M.A.; Jang, J.-K.; Chae, K.-J. Scalability of microbial electrochemical
technologies: Applications and challenges. Bioresour. Technol. 2022, 345, 126498. [CrossRef]
55. Behera, M.; Ghangrekar, M.M. Electricity generation in low cost microbial fuel cell made up of earthenware of different thickness.
Water Sci. Technol. 2011, 64, 2468–2473. [CrossRef]
56. Gryta, M. Resistance of Polypropylene Membrane to Oil Fouling during Membrane Distillation. Membranes 2021, 11, 552.
[CrossRef] [PubMed]
57. Dyartanti, E.R.; Purwanto, A.; Widiasa, I.N.; Susanto, H. Ionic Conductivity and Cycling Stability Improvement of PVDF/Nano-
Clay Using PVP as Polymer Electrolyte Membranes for LiFePO4 Batteries. Membranes 2018, 8, 36. [CrossRef] [PubMed]
58. Azaman, F.; Nor, M.A.A.M.; Abdullah, W.R.W.; Razali, M.H.; Zulkifli, R.C.; Zaini, M.A.A.; Ali, A. Review on natural clay ceramic
membrane: Fabrication and application in water and wastewater treatment. Malays. J. Fundam. Appl. Sci. 2021, 17, 62–78.
[CrossRef]
59. Winfield, J.; Gajda, I.; Greenman, J.; Ieropoulos, I. A review into the use of ceramics in microbial fuel cells. Bioresour. Technol. 2016,
215, 296–303. [CrossRef] [PubMed]
60. Pasternak, G.; Ormeno-Cano, N.; Rutkowski, P. Recycled waste polypropylene composite ceramic membranes for extended
lifetime of microbial fuel cells. Chem. Eng. J. 2021, 425, 130707. [CrossRef]
61. Sondhi, R.; Bhave, R.; Jung, G. Applications and benefits of ceramic membranes. Membr. Technol. 2003, 2003, 5–8. [CrossRef]
62. Mohyudin, S.; Farooq, R.; Jubeen, F.; Rasheed, T.; Fatima, M.; Sher, F. Microbial fuel cells a state-of-the-art technology for
wastewater treatment and bioelectricity generation. Environ. Res. 2022, 204, 112387. [CrossRef] [PubMed]
63. Eray, E.; Candelario, V.M.; Boffa, V. Ceramic Processing of Silicon Carbide Membranes with the Aid of Aluminum Nitrate
Nonahydrate: Preparation, Characterization, and Performance. Membranes 2021, 11, 714. [CrossRef] [PubMed]
64. Merino-Jimenez, I.; Gonzalez-Juarez, F.; Greenman, J.; Ieropoulos, I. Effect of the ceramic membrane properties on the microbial
fuel cell power output and catholyte generation. J. Power Sources 2019, 429, 30–37. [CrossRef]
65. Palanisamy, G.; Jung, H.-Y.; Sadhasivam, T.; Kurkuri, M.D.; Kim, S.C.; Roh, S.-H. A comprehensive review on microbial fuel cell
technologies: Processes, utilization, and advanced developments in electrodes and membranes. J. Clean. Prod. 2019, 221, 598–621.
[CrossRef]
66. Cheraghipoor, M.; Mohebbi-Kalhori, D.; Noroozifar, M.; Maghsoodlou, M.T. Production of greener energy in microbial fuel cell
with ceramic separator fabricated using native soils: Effect of lattice and porous SiO2 . Fuel 2021, 284, 118938. [CrossRef]
67. Suransh, J.; Tiwari, A.K.; Mungray, A.K. Modification of clayware ceramic membrane for enhancing the performance of microbial
fuel cell. Environ. Prog. Sustain. Energy 2020, 39, e13427. [CrossRef]
68. Ghadge, A.N.; Jadhav, D.A.; Ghangrekar, M.M. Wastewater treatment in pilot-scale microbial fuel cell using multielectrode
assembly with ceramic separator suitable for field applications. Environ. Prog. Sustain. Energy 2016, 35, 1809–1817. [CrossRef]
69. Freedman, J.C. Cell Membranes; Elsevier eBooks: Amsterdam, The Netherlands, 2012.
70. Chatterjee, P.; Ghangrekar, M.M. Design of Clayware Separator-Electrode Assembly for Treatment of Wastewater in Microbial
Fuel Cells. Appl. Biochem. Biotechnol. 2014, 173, 378–390. [CrossRef]
71. Bakonyi, P.; Koók, L.; Kumar, G.; Tóth, G.; Rózsenberszki, T.; Nguyen, D.D.; Chang, S.W.; Zhen, G.; Bélafi-Bakó, K.; Nemestóthy,
N. Architectural engineering of bioelectrochemical systems from the perspective of polymeric membrane separators: A compre-
hensive update on recent progress and future prospects. J. Membr. Sci. 2018, 564, 508–522. [CrossRef]
72. Logan, B.E. Microbial Fuel Cells; John Wiley & Sons: Hoboken, NJ, USA, 2008.
73. Foorginezhad, S.; Rezvannasab, G.; Asadnia, M. Natural clay membranes: A sustainable and affordable solution for treating dye
solutions, coal mine washery waste, and aquaculture wastewater. J. Water Process. Eng. 2023, 54, 104012. [CrossRef]
74. Yar’adua, M.M.; Kakale, A.U. Environmental Sustainability: Clay Solution to High Cost of Building Materials in Construction
Industry. Br. J. Multidiscip. Adv. Stud. 2018, 2, 82–87.
75. Slate, A.J.; Whitehead, K.A.; Brownson, D.A.; Banks, C.E. Microbial fuel cells: An overview of current technology. Renew. Sustain.
Energy Rev. 2019, 101, 60–81. [CrossRef]
Water 2024, 16, 1597 20 of 21

76. Richerson, D.W.; Lee, W.E. Modern Ceramic Engineering: Properties, Processing, and Use in Design; CRC Press: Boca Raton, FL, USA,
2018; p. 836.
77. Samaei, S.M.; Gato-Trinidad, S.; Altaee, A. The application of pressure-driven ceramic membrane technology for the treatment of
industrial wastewaters—A review. Sep. Purif. Technol. 2018, 200, 198–220. [CrossRef]
78. Hubadillah, S.K.; Othman, M.H.D.; Matsuura, T.; Ismail, A.; Rahman, M.A.; Harun, Z.; Jaafar, J.; Nomura, M. Fabrications and
applications of low cost ceramic membrane from kaolin: A comprehensive review. Ceram. Int. 2018, 44, 4538–4560. [CrossRef]
79. Arumugham, T.; Kaleekkal, N.J.; Gopal, S.; Nambikkattu, J.; Rambabu, K.; Aboulella, A.M.; Wickramasinghe, S.R.; Banat, F.
Recent developments in porous ceramic membranes for wastewater treatment and desalination: A review. J. Environ. Manag.
2021, 293, 112925. [CrossRef] [PubMed]
80. Li, K. Ceramic Membranes for Separation and Reaction; John Wiley & Sons: London, UK, 2007.
81. Ahmad, H.B. CERAMIC MEMBRANES: NEW TRENDS AND PROSPECTS (SHORT REVIEW). Water and water purification
technologies. Sci. Tech. News 2020, 27, 4–31.
82. Issaoui, M.; Limousy, L. Low-cost ceramic membranes: Synthesis, classifications, and applications. Comptes Rendus Chim. 2019, 22,
175–187. [CrossRef]
83. Omar, N.M.A.; Othman, M.H.D.; Tai, Z.S.; Milad, M.; Sokri, M.N.M.; Puteh, M.H. Recent progress and technical improvement
strategies for mitigating ceramic membrane bottlenecks in water purification processes: A review. Int. J. Appl. Ceram. Technol.
2023, 20, 3327–3356. [CrossRef]
84. Dickinson, E.J.F.; Smith, G. Modelling the Proton-Conductive Membrane in Practical Polymer Electrolyte Membrane Fuel Cell
(PEMFC) Simulation: A Review. Membranes 2020, 10, 310. [CrossRef] [PubMed]
85. Ayyaru, S.; Dharmalingam, S. Enhanced response of microbial fuel cell using sulfonated poly ether ether ketone membrane as a
biochemical oxygen demand sensor. Anal. Chim. Acta 2014, 818, 15–22. [CrossRef]
86. Sabina-Delgado, A.; Kamaraj, S.K.; Hernández-Montoya, V.; Cervantes, F.J. Novel carbon-ceramic composite membranes with
high cation exchange properties for use in microbial fuel cell and electricity generation. Int. J. Hydrogen Energy 2023, 48,
25512–25526. [CrossRef]
87. Banerjee, A.; Calay, R.K.; Eregno, F.E. Role and Important Properties of a Membrane with Its Recent Advancement in a Microbial
Fuel Cell. Energies 2022, 15, 444. [CrossRef]
88. Yee, R.S.L.; Zhang, K.; Ladewig, B.P. The Effects of Sulfonated Poly(ether ether ketone) Ion Exchange Preparation Conditions on
Membrane Properties. Membranes 2013, 3, 182–195. [CrossRef]
89. Yousefi, V.; Mohebbi-Kalhori, D.; Samimi, A. Start-up investigation of the self-assembled chitosan/montmorillonite nanocom-
posite over the ceramic support as a low-cost membrane for microbial fuel cell application. Int. J. Hydrogen Energy 2020, 45,
4804–4820. [CrossRef]
90. Yousefi, V.; Mohebbi-Kalhori, D.; Samimi, A. Application of layer-by-layer assembled chitosan/montmorillonite nanocomposite
as oxygen barrier film over the ceramic separator of the microbial fuel cell. Electrochim. Acta 2018, 283, 234–247. [CrossRef]
91. Sarma, P.J.; Mohanty, K. Epipremnum aureum and Dracaena braunii as indoor plants for enhanced bio-electricity generation in a
plant microbial fuel cell with electrochemically modified carbon fiber brush anode. J. Biosci. Bioeng. 2018, 126, 404–410. [CrossRef]
[PubMed]
92. Khandelwal, A.; Chhabra, M.; Yadav, P. Performance evaluation of algae assisted microbial fuel cell under outdoor conditions.
Bioresour. Technol. 2020, 310, 123418. [CrossRef] [PubMed]
93. Bagchi, S.; Behera, M. Performance evaluation of microbial fuel cells employing ceramic separator of different surface area
modified with mineral cation exchanger. SN Appl. Sci. 2020, 2, 1–8. [CrossRef]
94. Gunaseelan, K.; Jadhav, D.A.; Gajalakshmi, S.; Pant, D. Blending of microbial inocula: An effective strategy for performance
enhancement of clayware Biophotovoltaics microbial fuel cells. Bioresour. Technol. 2021, 323, 124564. [CrossRef] [PubMed]
95. Raychaudhuri, A.; Sahoo, R.N.; Behera, M. Application of clayware ceramic separator modified with silica in microbial fuel cell
for bioelectricity generation during rice mill wastewater treatment. Water Sci. Technol. 2021, 84, 66–76. [CrossRef] [PubMed]
96. Sarma, P.J.; Mohanty, K. A novel three-chamber modular PMFC with bentonite/fly ash based clay membrane and oxygen
reducing biocathode for long term sustainable bioelectricity generation. Bioelectrochemistry 2022, 144, 107996.
97. Babanova, S.; Jones, J.; Phadke, S.; Lu, M.; Angulo, C.; Garcia, J.; Carpenter, K.; Cortese, R.; Chen, S.; Phan, T.; et al. Continuous
flow, large-scale, microbial fuel cell system for the sustained treatment of swine waste. Water Environ. Res. 2020, 92, 60–72.
[CrossRef] [PubMed]
98. Cheraghipoor, M.; Mohebbi-Kalhori, D.; Noroozifar, M.; Maghsoodlou, M.T. Comparative study of bioelectricity generation in
a microbial fuel cell using ceramic membranes made of ceramic powder, Kalporgan’s soil, and acid leached Kalporgan’s soil.
Energy 2019, 178, 368–377. [CrossRef]
99. Neethu, B.; Bhowmick, G.; Ghangrekar, M. A novel proton exchange membrane developed from clay and activated carbon
derived from coconut shell for application in microbial fuel cell. Biochem. Eng. J. 2019, 148, 170–177. [CrossRef]
100. Raychaudhuri, A.; Behera, M. Ceramic membrane modified with rice husk ash for application in microbial fuel cells. Electrochim.
Acta 2020, 363, 137261. [CrossRef]
101. Das, I.; Das, S.; Sharma, S.; Ghangrekar, M.M. Ameliorated performance of a microbial fuel cell operated with an alkali pre-treated
clayware ceramic membrane. Int. J. Hydrogen Energy 2020, 45, 16787–16798. [CrossRef]
Water 2024, 16, 1597 21 of 21

102. Das, I.; Das, S.; Dixit, R.; Ghangrekar, M.M. Goethite supplemented natural clay ceramic as an alternative proton exchange
membrane and its application in microbial fuel cell. Ionics 2020, 26, 3061–3072. [CrossRef]
103. Rashid, T.; Sher, F.; Hazafa, A.; Hashmi, R.Q.; Zafar, A.; Rasheed, T.; Hussain, S. Design and feasibility study of novel paraboloid
graphite based microbial fuel cell for bioelectrogenesis and pharmaceutical wastewater treatment. J. Environ. Chem. Eng. 2021,
9, 104502. [CrossRef]
104. Das, I.; Ghangrekar, M.M.; Satyakam, R.; Srivastava, P.; Khan, S.; Pandey, H.N. On-Site Sanitary Wastewater Treatment System
Using 720-L Stacked Microbial Fuel Cell: Case Study. J. Hazard. Toxic Radioact. Waste 2020, 24, 04020025. [CrossRef]
105. Obasi, L.A.; Onukwuli, O.D.; Okoye, C.C. Performance of microbial fuel cell operating with clay-manihot starch composite proton
exchange membrane using RSM. Curr. Res. Green Sustain. Chem. 2021, 4, 100117. [CrossRef]
106. Rodríguez, J.; Mais, L.; Campana, R.; Piroddi, L.; Mascia, M.; Gurauskis, J.; Vacca, A.; Palmas, S. Comprehensive characterization
of a cost-effective microbial fuel cell with Pt-free catalyst cathode and slip-casted ceramic membrane. Int. J. Hydrogen Energy 2021,
46, 26205–26223. [CrossRef]
107. Mittal, Y.; Dash, S.; Srivastava, P.; Mishra, P.M.; Aminabhavi, T.M.; Yadav, A.K. Azo dye containing wastewater treatment in
earthen membrane based unplanted two chambered constructed wetlands-microbial fuel cells: A new design for enhanced
performance. Chem. Eng. J. 2022, 427, 131856. [CrossRef]
108. Otake, K.; Kitagawa, H. Control of Proton-Conductive Behavior with Nanoenvironment within Metal–Organic Materials. Small
2021, 17, 2006189. [CrossRef]
109. Gurjar, R.; Behera, M. Exploring necessity to pre-treat organic fraction of waste prior to use in an earthen MFC modified with
bentonite. Water Sci. Technol. 2022, 86, 656–671. [CrossRef]

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