Eco-friendly approach for tannery effluent treatment and CO2 sequestration using unicellular green oleaginous microalga Tetradesmus obliquus TS03.

The present study explored the process of bioremediation, sequestration of carbon dioxide, and biofuel production using multifarious potent freshwater microalgae Tetradesmus obliquus TS03. The heavy metals were reduced, viz., 8.34 mg of cadmium (95.13%), 4.56 mg of chromium (97.28%), 1.34 mg of copper (98.67%), 1.24 mg of cobalt (98.19%), 1.93 mg of lead (96.72%), 2.31 mg of nickel (97.14%), and 2.23 mgL-1 of zinc (96.59%) using photobioreactor microalgal treatment method. The heavy metal biosorption capacity rate (qmax) was 98.90% determined by the Langmuir and Freundlich isotherm kinetics model at 10 days of effluent treatment using Tetradesmus obliquus TS03. The microalgae T. obliquus TS03 utilized 98.34% of carbon dioxide (CO2) enhanced by acetyl CoA carboxylase and RuBisCO enzymes. The biodiesel was extracted from microalga and identified 32 fatty acid methyl ester major compounds viz., tetradecanoate methyl ester, hexadecanoic acid methyl ester, tridecanoic acid methyl ester, heptadecatrienoic acid methyl ester, octadecanoic acid methyl ester, eicosanoic acid methyl ester, pentadecanoic acid methyl ester, and cis-methylicosanoate using gas mass chromatography (GCMS). The biodiesel functional groups were identified, viz., amides, phenols, alcohols, alkynes, carboxylic acids, carbonyls, and ketones groups using Fourier transformation infrared (FTIR). The bioethanol was identified using high-performance liquid chromatography (HPLC) and determined the peak presented at RT of 4.35 min (75,693.1046 µV s-1).

Integrating eco-technological approach for textile dye effluent treatment and carbon dioxide capturing from unicellular microalga Chlorella vulgaris RDS03: a synergistic method.

A pilot-scale treatment method was used in the present study to test the biosorption of textile dye from textile effluent and carbon dioxide using Chlorella vulgaris RDS03. The textile dye effluent treatment achieved that textile dye biosorption capacity (qmax) rate of 98.84% on 15 days of treatment using Chlorella vulgaris RDS03. The Langmuir and Freundlich isotherm kinetics model indicated that the higher R2 value 0.98. The microalga Chlorella vulgaris RDS03 was captured-96.86% of CO2 analyzed by CO2 utilization and biofixation kinetics, 4.65 mgmL-1 of biomass, 189.26 mgg-1 of carbohydrate, 233.89 mgg-1 of lipid, 4.3 mLg-1 of bioethanol and 4.9 mLg-1 of biodiesel produced. We performed fatty acid methyl ester (FAME) profiling using gas chromatography-mass spectrometry (GCMS). We found 40 types of biodiesel compounds, specifically myristic acid, pentadecanoic acid, octadecanoic acid, palmitic acid, and oleic acid. The high-performance liquid chromatography (HPLC) validated and analyzed the produced bioethanol.Novelty of the Research• Unicellular microalga Chlorella vulgaris RDS03 was isolated from the freshwater region and investigated their biosorption efficiency against hazardous synthetic azo textile dyes.• Chlorella vulgaris RDS03 ability to biosorption 96.86% of environmental polluted carbon dioxide• Treated biomass was used to produce ecofriendly, unpolluted and green energy such as biofuels (biodiesel and bioethanol).

Exploration of green integrated approach for effluent treatment through mass culture and biofuel production from unicellular alga, Acutodesmus obliquus RDS01.

This study deals with the open pond (OP) pilot scale treatment of cassava effluent and enhancement of Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) enzyme through CO2 utilization by the microalga, Acutodesmus obliquus RDS01. The cassava effluent treatment (ET) revealed maximum reduction of ammonia (96.8%), calcium (94.6%), chloride (95.2%), chlorine (98.5%), inorganic phosphate (94.6%), magnesium (96.8%), nitrate (96.89%), organic carbon (95.9%), organic phosphorus (96.3%), potassium (97.9%), sodium (97.1%), and sulfate (95.4%) on 15th day using A. obliquus. The microalga produced highest RuBisCO enzyme activity (90%), CO2 utilization efficiency (95%), biomass (8.9 gL-1), lipid (176.65 mg mL-1), carbohydrate (96.78 mg mL-1), biodiesel (4.1 mL g-1), and bioethanol (3.7 mL g-1) during OP treatment. The isolated RuBisCO gene (rbcL) was used to construct the protein model by homology modeling. The microalgal-lipid content was analyzed through thin layer chromatography, the biodiesel produced was analyzed using Fourier-transform infrared spectroscopy and gas chromatography mass spectrometry (GCMS). The bioethanol production was confirmed by high performance liquid chromatography and GCMS analyses. A. obliquus produced of 98.75% biodiesel and 96.83% bioethanol in the OP pilot scale treatment A. obliquus. Overall, the microalga A. obliquus could act as an effective CO2 capturing and bioremediation agent in the cassava ET, and also for the biodiesel and bioethanol can be produced.