In the present study, a sediment microbial fuel cell (SMFC) was added to an open channel previously containing another SMFC. Interaction between the two SMFCs was investigated when the new SMFC was located either in downstream or upstream of the former SMFC. Addition of new SMFC in both cases caused a 24–25 % voltage increase in the former SMFC and eliminated initial voltage fluctuations in the new SMFC. Furthermore, voltage loss was studied in two stacked SMFCs operating in open channels, whether both SMFCs operated simultaneously from beginning of operation or added to the channel sequentially. It was observed that in both cases, the SMFC whose anode was used to establish series connection experienced a considerable increase in its anode potential that led to voltage loss in the SMFC. As an example, one of the SMFCs whose anode was connected in series produced an open circuit voltage of 124 mV compared to 716 mV in single mode, although 621 mV was produced when cathode was connected in series. Findings of this study showed the presence of interactions between SMFCs in open channels as well as simultaneous influence of electrical and hydraulic connection on voltage drop within SMFCs.

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