Effect of pH and distance between electrodes on the
performance of a sediment microbial fuel cell
T. K. Sajana, M. M. Ghangrekar and A. Mitra
ABSTRACT
The performance of three sediment microbial fuel cells (SMFCs) was evaluated at different feed
water pH and electrode spacing for chemical oxygen demand (COD) removal, total nitrogen (TN)
removal, and power density; while offering in situ remediation of aquaculture pond water. SMFC-A
was operated at the feed water pH of 6.5 and spacing between the electrodes of 100 cm. SMFC-B
and SMFC-C were operated at feed water pHs of 8.5 and 6.5, respectively, and distance between
electrodes of 50 cm. The anode and cathode were connected with concealed copper wire through an
external load of 100 Ω. The average amount of total COD removal rate and TN removal rate, per unit
area of cathode, were 1.72 ± 0.06 and 0.021 ± 0.007 g/m
2
d in SMFC-A, 1.03 ± 0.08 and 0.024 ±
0.005 g/m
2
d in SMFC-B, and 1.14 ± 0.01 and 0.017 ± 0.001 g/m
2
d in SMFC-C, respectively. SMFC-A,
operated with higher distance between electrodes, demonstrated better removal of organic matter
and highest open circuit voltage of 0.903 V. SMFCs with less feed pH (6.5) gave higher COD removal
and feed pH of 8.5 gave higher TN removal. SMFCs operated with lesser distance between electrodes
gave higher power density.
T. K. Sajana
A. Mitra
Department of Agricultural and Food Engineering,
Indian Institute of Technology,
Kharagpur 721 302,
India
M. M. Ghangrekar (corresponding author)
Department of Civil Engineering,
Indian Institute of Technology,
Kharagpur 721 302,
India
E-mail: ghangrekar@civil.iitkgp.ernet.in
Key words | electrode spacing, in situ aquaculture water remediation, pH, sediment microbial
fuel cell
INTRODUCTION
Sediment microbial fuel cells (SMFCs) generate electricity
from the electro-potential difference between oxic water
and anoxic sediments. SMFCs are attracting the attention
of the scientist to develop it for remediation of marine or
freshwater sediments and harness energy in the form of elec-
tricity. Reimers et al. () employed platinum mesh
electrodes to produce current from both salt marsh and estu-
arine sediments. One of the upcoming and most promising
approaches for in situ remediation of aquaculture water is
the use of SMFCs, which will offer simultaneous treatment
of aquaculture water while generating electricity. Microor-
ganisms in the family Geobacteraceae can oxidize organic
compounds by donating electrons to electrodes and this res-
piration shows promise as a strategy for harvesting
electricity from marine as well as freshwater sediments
and other sources of waste organic matter (Bond et al. ).
The performance of microbial fuel cells (MFCs) is
affected by many factors, such as electrode material (Park
& Zeikus ), distance between the electrodes (Cheng
et al. ; Hong et al. ), and pH (He et al. ;
Behera & Ghangrekar ). The pH of water is also an
important limiting factor in fish culture. The suitable pH
range for survival and growth of the fish is between 6.7
and 9.0 (Santhosh & Singh ). The wastewater treatment
and power generation in MFCs is affected by operating pH
in the anodic chamber. The highest current was observed
at a pH of between 7 and 8, and the current was lower at
a pH of 9 (He et al. ). Most MFCs are operated at neu-
tral pH in order to optimize bacterial growth conditions.
The maximum power generated in a single-chamber air
cathode MFC has previously been shown to increase when
the spacing between the electrodes is decreased from 4 to
2 cm (Cheng et al. ). When SMFCs are to be used for
in situ remediation of aquaculture water, the distance
between the electrodes will depend on the overall depth of
the water used in the aquaculture pond. The depth of a
water body plays an important role in aquaculture because
depth requirement varies from organism to organism under
culture (Santhosh & Singh ). This depth of water in an
aquaculture pond is generally in the range of 0.5–2.5 m.
537 © IWA Publishing 2013 Water Science & Technology | 68.3 | 2013
doi: 10.2166/wst.2013.271