Electrical current generation from a continuous flow macrophyte biocathode sediment microbial fuel cell (mSMFC) during the degradation of pollutants in urban river sediment

A new type of sediment microbial fuel cell (SMFC) with floating macrophyteLimnobium laevigatum,Pistia stratiotes, orLemna minorL. biocathode was constructed and assessed in three phases at different hydraulic retention time (HRT) for electrical current generation during the degradation of urban river sediment. The results showed a highest voltage output of 0.88 +/- 0.1 V, maximum power density of 80.22 mW m(-3), highest columbic efficiency of 15.3%, normalized energy recovery of 0.030 kWh m(-3), and normalized energy production of 0.005 kWh m(-3)in theLemna minorL. SMFC during phase 3 at HRT of 48 h, respectively. Highest removal efficiencies of total chemical oxygen demand of 80%, nitrite of 99%, ammonia of 93%, and phosphorus of 94% were achieved inLemna minorL. system, and 99% of nitrate removal and 99% of sulfate removal were achieved inPistia stratiotesandLimnobium laevigatumsystem during the SMFC operation, respectively.Pistia stratiotesexhibited the highest growth in terms of biomass and tap root system of 29.35 g and 12.2 cm to produce the maximum dissolved oxygen of 16.85 +/- 0.2 mg L(-1)compared with other macrophytes. The predominant bacterial phylumProteobacteriaof 62.86% and genusExiguobacteriumof 17.48% were identified inLimnobium laevigatumsystem, while the classGammaproteobacteriaof 28.77% was observed in the control SMFC. The integration of technologies with the continuous flow operation shows promising prospect in the remediation of polluted urban river sediments along with the generation of electrical current.