This paper describes the potential for algal biomass production in conjunction with wastewater treatment
and power generation within a fully biotic Microbial Fuel Cell (MFC). The anaerobic biofilm in the
anodic half-cell is generating current, whereas the phototrophic biofilm on the cathode is providing the
oxygen for the Oxygen Reduction Reaction (ORR) and forming biomass. The MFC is producing electricity
with simultaneous biomass regeneration in the cathodic half-cell, which is dependent on the nutrient
value of the anodic feedstock. Growth of algal biomass in the cathode was monitored, assessed and
compared against the MFC power production (charge transfer), during this process. MFC generation of
electricity activated the cation crossover for the formation of biomass, which has been harvested and
reused as energy source in a closed loop system. It can be concluded that the nutrient reclamation and
assimilation into new biomass increases the energy efficiency. This work is presenting a simple and selfsustainable
MFC operation with minimal dependency on chemicals and an energy generation system
utilising waste products and maximising energy turnover through an additional biomass recovery.
© 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license
This work is aiming to: i) demonstrate the operation of a fully
biological microbial fuel cell with an anaerobic anode and a photosynthetic
cathode colonised by the mixed culture of photosynthetic
organisms; ii) investigate the relationship between the development
of the cathodic biofilm andMFC power generation and iii) utilise the
harvested biomass directly as a feedstock for the MFC anodes.
2. Materials and methods
2.1. MFC design
MFC reactors comprised 25 mL anode chambers and 25 mL
cathode chambers, separated by a cation exchange membrane
(VWR International) as previously described [16]. The electrode
materialwas carbon fibre veil with a total area of 270 cm2 (20 g/m2)
(PRF Composite Materials, Poole, UK) used in both the anode and
cathode chambers. Carbon veil sheets were folded down into
rectangular cuboids and connected with a nickel-chrome wire
(thickness-0.45 mm) to the external circuit. The cathode electrodes
were modified in 5 different experimental groups (Table 1) and
included two control conditions, i.e. one control group with no
electrode modification and an abiotic control (algae water) and 4
experimental groups with: a) non modified cathode electrode
(algae); b) cotton string (thickness-2 mm) wrapped around the
electrode (algae string); c) cellulose layer (thickness-1 mm) coating
around the electrode (algae cellulose); d) stainless steel wire (type
316, thickness 0.45). The modifications were employed to support
algal biofilm development on the cathode electrode and for current
collection. Each experimental condition was tested in triplicate
resulting in a total of 15 MFCs. No growth media, pH control or
chemical pre-treatment were used.