Development of Microalgae-microbial Fuel Cell (MmFC) Technology using Microalgae Consortium of Chlorella vulgaris and Spirulina Platensis

Abstract

Microalgae-microbial Fuel Cell (MmFC) is a type of Microbial Fuel Cell (MFC) that is integrated with the microalgae cultivation system. This device is capable of supplying electron acceptor (oxygen) that are naturally produced by microalgae that are not found in common MFCs. In this study, the development of MmFC was carried out using a consortium of microalgae consisting of Chlorella vulgaris and Spirulina vulgaris as the most studied microalgae and have the potential to support each other in terms of growth. Spirulina is known to provide compounds that support the growth of microalgae such as vitamins and inorganic nutrients. This research began with a preculture in F/2 medium using various ratios of Chlorella:Spirulina consortium composition ratios (1:0, 0:1, 1:1, 2:1, 3:2). The consortium at 3:2 ratio produced highest biomass and growth rate of 3.94 g/L at the 222nd hour and 0.021/hour at the 110th hour. This consortium also produced the highest oxygen content that could be used as an electron acceptor, which was 6.77 mg/L at 192 hours. The consortium was then cultured in a 500 mL MmFC dual-chamber device equipped with a Nafion 117 membrane and carbon (graphite) rod electrodes. The cathode compartment is used for the cultivation of the microalgae consortium, while the anode compartment is filled with artificial tempe (fermented soybean cake) wastewater containing indigenous microbes capable of degrading organic compounds. After 49 hours of operation, the highest voltage and electric power obtained are 437.1 mV and 1.911 mW, respectively, at 24 hours with anode surface area of 59.06 cm2