Removal of organic pollutants from saline waste using Dunaliella and halophilic bacteria in photomicrobial fuel cells

Abstract

The increasing challenge of treating saline wastewater while recovering energy highlights the need for sustainable and efficient solutions. This study presents the performance of a halophilic bacteria and Dunaliella salina-assisted photomicrobial fuel cell (PMFC) in an outdoor operation for COD removal and simultaneously energy production. The PMFCs made of inexpensive material were used for organic matter removal in saline wastewater (between the salinity range 0.5M–1.5M). Lipid-extracted algae (LEA) and starch were used as electron donors at the anode. D. salina at the cathode produces oxygen as an electron acceptor and serves as a valuable source of lipids, glycerol, and β-carotene. The PMFCs were characterized for energy recovery, algae biomass production, and microbial composition. The 0.5M LEA-fed PMFCs produced the highest operating voltage of 615 ± 79 mV across the 100 Ω register and 0.496 kWh/m³ of net energy. Further metagenomic analyses of the operating systems were analyzed to better understand microbial interactions. The comparison of the metagenomic profile of the anodic biofilm of 0.5M LEA-fed PMFC and 1.5M LEA-fed PMFC showed the dominance of the halophilic hat can use complex substrates electrogens like Pseudomonas (0.5M-13.61 %; 1.5M-1.73 %), Blastopirellula (0.5M-13.44 %; 1.5M-0.62 %), Halomonas (0.5M-1.21 %; 1.5M-33.26 %), and Lentimicrobium (0.5M-8.67 %; 1.5M-3.92 %). This work highlights the practical importance of PMFCs in the treatment of saline wastewater, offering both efficient COD removal and sustainable energy generation. The results provide insights into managing microbial communities to improve the performance of the operating PMFCs, facilitating wider applications in saline wastewater management.