Optimising the early stages of constructed wetland-microbial fuel cell lifecycle: a guide to plant selection, acclimatisation, and start-up

Diagram showing the lifecycle of a constructed wetland–microbial fuel cell (CW-MFC): design, construction, plant adaptation, start-up and operation. Each stage is illustrated with a photograph or drawing beside a central cross-section of a planted cylindrical reactor containing layered gravel and electrodes. Constructed wetland-microbial fuel cells (CW-MFCs) progress through a life cycle from design to operation, during which wastewater is treated and power generated. Research has focussed on the operational phase, overlooking how the earlier phases of plant adaptation and start-up shape performance; the role of plants during these phases remains poorly understood. This study addresses that gap through a step-by-step framework for the initial phases of the CW-MFC life cycle, establishing a baseline that clarifies their function and improves rigour in the field. To the authors' knowledge, it is the first CW-MFC study to combine criterion-based plant selection with a parallel record of biomass development and open-circuit voltage through start-up. Four Australian native species (Phragmites, Juncus, Philydrum and Eleocharis) were selected, adapted, and assessed during start-up. The highest maximum power density was obtained in Juncus cells at 14.4 mW/m2, 4.2 times that of the control (3.45 mW/m2), followed by Phragmites at 12.6 mW/m2. Faster voltage establishment and better performance correlated with biomass growth rather than plant species, highlighting the role of growing plants in enhancing cell voltage and reducing start-up time. The results suggest that voltage output could act as a biosensor for plant biomass growth, although this rests on correlated time trends and requires further testing.