Nadzri, N.A.A., Mohd Yasin, N.H.  , Thanokodi, S. , Takriff, M.S.  and Abu Bakar, M.H

Keywords: Microbial desalination cell, Microalgae, Renewable energy, Desalination, Bioelectricity

Abstract: Reduction of fossil fuels, climate changes and environmental pollution increases the urge to find new sustainable energy. Microbial desalination cell (MDC) is a bio-based solution to this problem. It offers a sustainable approach to desalinate saltwater by directly utilizing the electrical power generated by the process of organic matter oxidation. Triple chamber MDC employs anaerobic bacteria to produce proton and electron in the anode chamber. The middle chamber consists of saltwater, act as a bridge to transfer an electron from anode to cathode. Meanwhile, the cathode chamber often uses a chemical such as ferric cyanide as an electron acceptor, which is not practical and toxic. Therefore, this study use locally isolated microalgae, Characiuum sp. UKM1, Chlorella sorokiniana UKM2, Coelastrella sp. UKM4, Chlamydomonas sp. UKM6 and Scenedesmus sp. UKM9 to take the role of the terminal electron acceptor. Microalgae cultivation and growth analysis have been done through biomass assessment showed that the maximum specific growth rate (μmax) of UKM1, UKM2, UKM4, UKM6 and UKM9 were 0.07036 day-1, 0.07323 day-1, 0.06428 day-1, 0.08147 day-1 and 0.06468 day-1, respectively. Apart from that, the assessment of dissolved oxygen and pigment production was also done to screen the photosynthetic performance of all local microalgae isolates. During the cultivation of microalgae, Scenedesmus sp. UKM9 produced the highest dissolved oxygen while Chlamydomonas sp. UKM6 produced the greatest amount of chlorophyll which is 12.143 mg/m-3 due to photosynthesis. Both of the microalgae species were chosen as biocathodes in the PhMDC. In terms of bioelectricity generation, Scenedesmus sp. UKM9 produced higher electricity than Chlamydomonas sp. UKM6. Therefore, we can conclude that microalgae that can produce a great amount of dissolved oxygen showed better potential as biocathode in PhMDC. Consequently, the complete set of this PhMDC exhibited a better perspective of sustainable energy generation.  

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