Alkali production from bipolar membrane electrodialysis powered by microbial fuel cell and application for biogas upgrading

The biogas upgrading is necessary for its application, and alkali CO2 adsorption is one efficient method. In this study, a coupled system, bipolar membrane electrodialysis (BPMED)–microbial fuel cell (MFC), was proposed for alkali production, which could also realize electricity in situ utilization. It was found that the pH in the alkali production chamber was 9.8. With higher NaCl concentration, bigger applied voltage and lower external resistance, the pH of the produced alkali solution also increased and the maximum value of which was 11.6. Meanwhile, our system also performed desalination. Furthermore, the produced alkali solution was utilized for biogas upgrading. The CO2 content decreased notably in headspace, which even reached 0% at pH 11.6 of alkali solution. This study provides an elegant and sustainable way to extend BPMED and MFC application.

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► BPMED powered by MFC was proposed to utilize electricity in situ and produce NaOH.
► The maximum pH was about 11.6 with 0.5 V applied voltage.
► The produced NaOH was suitable for biogas upgrading and the final CH4 reached 100%.
► The study provides an elegant and sustainable way to extend BPMED & MFC application.