Beyond enhancement of macrophyte litter decomposition in sediments from a terrestrializated shallow lake through bioanode employment

• SMFC enhanced the decomposition of macrophyte litter in sediments.
• Enhanced degradation of recalcitrant carbons by SMFC improved humification.
• SMFC enriched aromatic compounds-degrading bacteria.
• Methanogen growth was inhibited by microbial anode during experiments.
• SMFC might be exploited against lake terrestrialization process.

The accumulation of excess decayed macrophyte litter in sediments of shallow lakes can lead to ecological deterioration. This work investigated the impact of sediment microbial fuel cell (SMFC) employment in macrophyte litter degradation in sediments and is based on 700 days of lab experiments. The results showed removal efficiencies of total organic carbon (TOC) at three depths (0–8 cm, 8–18 cm, and 18–28 cm) in SMFC-amended sediments, which increased by 18.9%, 20.9%, and 20.8%, respectively. Moreover, SMFC enhanced the degradation of recalcitrant carbons and stimulated humification of organic matter in sediments, which might benefit carbon sequestration in the long term. Pyrosequencing analysis showed that a relatively high proportion of aromatic compounds-degrading bacteria were detected in SMFC-employed sediments, although SMFC did not noticeably change the bacterial and archaeal community structures in sediments. Also, the methanogen growth in sediments over the whole experimental period was inhibited with SMFC employment. Considering both enhanced litter biodegradation and methanogen depression, SMFC could be exploited as a new and promising way to delay lake terrestrialization.