In situ electrochemical remediation of brackish river sediment rich in aromatic organic matter using steel-slag-combined sediment microbial fuel cells

Steel slag was employed as an additional substrate for power generation in sediment microbial fuel cells (SMFCs), and its role in the degradation of recalcitrant organic matter and sediment remediation was investigated. Steel slag improved the degradation of soil organic matter (SOM) in SMFC by 69 % compared to an individual SMFC with a 6.3-times higher charge production. Thermogravimetric and infrared spectroscopy analyses showed that steel slag humified SOM whereas the SMFC oxidatively degraded it. The humification by steel slag was attributed to the coordination with iron, it facilitated the accessibility of oxygen and stimulated oxidative degradation by the SMFC. As a result, aliphatic and aromatic compounds were degraded by 53 and 44 wt %, respectively, compared to the control. Additionally, ferrous ions eluted from the steel slag precipitated highly concentrated hydrogen sulfide as ferrous sulfide, leading to a noticeable increase in the voltage potential with respect to a standard hydrogen electrode (Eh) in the sediments. Overall, steel slag significantly enhances the efficiency of renewable energy production of SMFCs, and contributes to the remediation of benthic ecosystem by the development of aliphatic recalcitrant organic matter and increase in oxidation-reduction potential.

Automated summary

Steel slag as an additional substrate in SMFCs significantly enhances the efficiency of renewable energy production and contributes to the remediation of benthic ecosystem by facilitating the degradation of recalcitrant organic matter and increasing oxidation-reduction potential.