Abstract
The possibility of using rainwater as a sustainable anolyte in an air-cathode microbial fuel cell (MFC) is investigated in this study. The results indicate that the proposed MFC can work within a wide temperature range (from 0 to 30°C) and under aerobic or anaerobic conditions. However, the rainwater season has a distinct impact. Under anaerobic conditions, the summer rainwater achieves a promised open circuit potential (OCP) of 553 ± 2 mV without addition of nutrients at the ambient temperature, while addition of nutrients leads to an increase in the cell voltage to 763 ± 3 and 588 ± 2 mV at 30°C and ambient temperature, respectively. The maximum OCP for the winter rainwater (492 ± 1.5 mV) is obtained when the reactor is exposed to the air (aerobic conditions) at ambient temperature. Furthermore, the winter rainwater MFC generates a maximum power output of 7 ± 0.1 mWm−2 at a corresponding current density value of 44 ± 0.7 mAm−2 at 30°C. While, at the ambient temperature, the maximum output power is obtained with the summer rainwater (7.2 ± 0.1 mWm−2 at 26 ± 0.5 mAm−2). Moreover, investigation of the bacterial diversity indicates that Lactobacillus spp. is the dominant electroactive genus in the summer rainwater, while in the winter rainwater, Staphylococcus spp. is the main electroactive bacteria. The cyclic voltammetry analysis confirms that the electrons are delivered directly from the bacterial biofilm to the anode surface and without mediators. Overall, this study opens a new avenue for using a novel sustainable type of MFC derived from rainwater.
Highlights
A microbial fuel cell (MFC) is a system in which the microorganisms can convert the chemical energy embedded in some organic compounds to electricity through the oxidation of these compounds into ATPs by sequential reactions [1,2,3]
As the proposed rainwater microbial fuel cell (RMFC) is supposed to work within a wide temperature range through the year, so the investigation process was carried out at the ambient conditions in winter as well as at 30°C
Using the summer and the winter rainwaters as anolytes revealed a noteworthy difference in MFCs performance
Summary
A microbial fuel cell (MFC) is a system in which the microorganisms can convert the chemical energy embedded in some organic compounds to electricity through the oxidation of these compounds into ATPs by sequential reactions [1,2,3]. The main difference between MFC and the other types of fuel cells is the living microorganism acts as a catalyst and oxidizes the organic materials present at the anode chamber [4,5,6]. The energy produced by MFC is relatively low, it possesses a unique feature in the fuel cells field; it can gain the chemical energy from several types of wastes naturally present in different environments with potential and direct conversion into electrical energy. It can be operated at a pH close to neutrality and room temperature. MFC can be considered the most convenient power-generating device for wireless sensors in remote areas [10,11]
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