Publication: Remediation of saline wastewater for organic pollutants using halophilic bacteria and Dunaliella salina
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2025-04-15
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Indian Institute of Technology, Jodhpur
Abstract
Industries such as leather, textile, food processing, and petroleum contribute to the rising salinity of freshwater supplies, producing significant quantities of saline wastewater. Conventional water treatment plants face difficulties in treating these effluents for organics removal because the high salinity causes membrane fouling and inhibits the growth of microorganisms. In order to tackle this problem, it is necessary to utilize a specific category of organisms capable of tolerating or thriving in high salt concentrations, known as halotolerant organisms, as biocatalysts. Physicochemical methods can remove salt, but the repeated buildup of organic compounds leads to increased energy consumption and decreased quality of the recovered salts. The Microbial Fuel Cell (MFC) is a suitable method for effectively utilizing saline wastewater. The study describes the cultivation of Dunaliella salina at the saline cathode in a photosynthetic microbial fuel cell (PMFC). The alga was isolated from Salt Lake Sambhar, Rajasthan, India, and identified using 18S rDNA sequencing analysis. The alga growth in PMFC was tested at 0.5 M to 1.5 M sodium chloride. The highest power and current density were obtained at 0.5 M NaCl with 213.38 mW/m2 and 1020.5 mA/m2, respectively. The specific growth rate of algae was 0.4 day−1 with 566 mg/l lipids and 348.9 ± 25.6 μg/ml of glycerol content at 0.5 M PMFC. The PMFC operating at 1.0 M NaCl led to high β-carotene production (24.42 ± 1.8 μg/100 mg). The salinity in natural water resources makes it challenging to apply them in bioprocesses. This study establishes the utility of D. salina in saline water- based PMFC for generating power and high-value Dunaliella biomass. A scaleup PMFC system with a 15-litre cathode and 2-litre anode was developed for the second study, utilizing Dunaliella lipid-extracted algae (LEA) biomass as an electron donor substrate at the anode. The operating system with LEA biomass generates a power density of 621.43 ± 129.47 mW/m2 and a net 0.496 kWh/m3 energy at 0.5 M salinity under outdoor conditions, reducing reliance on external substrates. Therefore, low-cost PMFCs can potentially treat saline wastewater with concomitant energy and high-value product generation.
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Mishra, Akanksha(2019).Remediation of saline wastewater for organic pollutants using halophilic bacteria and Dunaliella salina (Doctor's thesis). Indian Institute of Technology Jodhpur