Bioenergy generation and nitrogen removal in a novel ecological-microbial fuel cell.

Abstract

A novel ecological-microbial fuel cell (E-MFC) was constructed based on the mutualistic symbiosis relationship among wetland plants Ipomoea aquatic, benthic fauna Tubifex tubifex (T.\xa0tubifex) and microorganisms. The maximum power densities of sediment MFC (S-MFC), wetland plant MFC (WP-MFC) and E-MFC were 6.80\xa0mW/m2, 10.60\xa0mW/m2 and 15.59\xa0mW/m2, respectively. Ipomoea aquatic roots secreted organic matter as electricigens fuel for electricity generation, while T.\xa0tubifex decomposed decaying leaves and roots into soluble organic matter and plant nutrients, forming a co-dependent and mutually beneficial system, which was conducive to bioelectricity production. The E-MFC obtained the highest nitrogen removal, and the removal efficiencies of NH4+-N and NO3--N were 90.4% and 96.5%, respectively. Hydraulic retention time (HRT), cathodic aeration and T.\xa0tubifex abundance had significant effects on E-MFC power generation. The performeance boost of E-MFC was closely related to anodic microbial community change caused by the introduction of T.\xa0tubifex.