Effect of electrode modification on the production of electrical energy and degradation of Cr (VI) waste using tubular microbial fuel cell

Carcinogenic hexavalent chromium is increasing worldwide due to the increased electroplating, welding and textile industry. On the other hand, molasses, the sugar factory’s byproduct with high organic compounds (sugars), may pollute the environment if it is not processed. However, microbial fuel cell (MFC) seems to be a promising technology due to its ability to produce electrical energy from pollutant degradation using microbes while reducing hexavalent chromium to trivalent chromium with less toxicity. Carbon felt was used at both electrodes. This research aimed to determine the effect of modifying the anode with rice bran and cathode with Cu catalyst towards electricity generation and pollutant removal in molasses and reducing Cr (VI) into Cr (III) using tubular microbial fuel cells. Moreover, the effect of mixing Sidoarjo mud and Shewanella oneidensis MR-1 as electricigen bacteria toward electrical energy production and pollutant removal was determined. Experiments revealed that the S/CM/AM variable, which only used Shewanella oneidensis MR-1 as an electricigen bacteria with both modified electrodes, produced the highest total power density of 530.42 mW/m² and the highest percentage of Cr (VI) reduction of 98.87%. In contrast, the highest microbial population of 66.5 × 10¹⁰ cells/mL, 61.28% of Biological Oxygen Demand (BOD5) removal and 59.49% of Chemical Oxygen Demand (COD) were achieved by SSi/CM/AM variable, mixing Shewanella oneidensis MR-1 and Sidoarjo mud as an electricigen bacteria with both modified electrodes. Therefore, this study indicates that double chamber tubular microbial fuel cells may be a sustainable solution for managing molasses and carcinogen hexavalent chromium.