Enhancement of bioelectric parameters of multi-electrode plant–microbial fuel cells by combining of serial and parallel connection

Abstract

Innovative electro-biotechnology of plant–microbial fuel cell involves the use of electrodes for the collection of bioelectricity produced by soil rhizosphere microorganisms, utilizing products of photosynthesis and plant residues compounds. The performance of plant–microbial electro-biosystem is highly dependent on the electrode materials and their configurations. Various materials as electrodes for electro-biosystems were analyzed, conducting experiments in laboratory with indoor plants and in situ with forest and garden plants. Graphite wastes of electric transport as cathodes and perforated zinc-galvanized steel plates as anodes were selected as electrodes for plant–microbial fuel cell due to their electro-efficiency, low cost and sustainability in environment. To design multi-electrode system, electrodes were connected each other by copper wires into cathode and anode system. The use of graphite wastes and polyvinyl chloride-insulated copper wires promoted reduction of the cost of electro-biotechnology. Multi-electrode plant–microbial fuel cells with 12 anodes and 11 cathodes with Caltha palustris plants at 10 Ω produced current of 40.98 mA that is 10.1 times more than mono-electrode plant–microbial fuel cells. The parallel connection of two multi-electrode electro-biosystems was resulted in 2.1-fold increase in current compared to the current generated by the one multi-electrode electro-biosystem. The serial connection of three multi-electrode plant–microbial fuel cells was led to an increase in the bioelectric potential in 2.9 times; at the same time, their parallel connection did not increase voltage. Variations of parallel–serial connections of several multi-electrode plant–microbial fuel cells as energy subunits into one complex multi-electro-biosystem were appeared the way to maximize the receiving of plant–microbial bioelectricity.