Pilot scale wastewater treatment, CO₂ sequestration and lipid production using microalga, Neochloris aquatica RDS02

Abstract

In present investigation carried out large-scale treatment of tannery effluent by the cultivation of microalgae, Neochloris aquatica RDS02. The tannery effluent treatment revealed that significant reduction heavy metals were chromium-3.59, lead-2.85, nickel-1.9, cadmium-10.68, zinc-4.49, copper-0.95 and cobalt-1.86 mg/L on 15th day of treatment using N. aquatica RDS02. The microalgal biosorption capacity q_max rate was Cr-88.66, Pb-75.87, Ni-87.61, Cd-60.44, Co-52.86, Zn-84.90 and Cu-54.39, and isotherm model emphasized that the higher R² value 0.99 by Langmuir and Freundlich kinetics model. The microalga utilized highest CO₂ (90%) analyzed by CO₂ biofixation and utilization kinetics, biomass (3.9 mg/mL), lipid (210 mg mL⁻¹), carbohydrate (102.75 mg mL⁻¹), biodiesel (4.9 mL g⁻¹) and bioethanol (4.1 mL g⁻¹). The microalgal-lipid content was analyzed through Nile red staining. Gas chromatography mass spectrometric (GCMS) analysis confirmed that the presence of a biodiesel and major fatty acid methyl ester (FAME) profiling viz., tridecanoic acid methyl ester, pentadecanoic acid methyl ester, octadecanoic acid methyl ester, myristic acid methyl ester, palmitic acid methyl ester and oleic acid methyl ester. Fourier transform infrared (FTIR) analysis confirmed that the presence of a functional groups viz., phenols, alcohols, alkynes, carboxylic acids, ketones, carbonyl and ester groups. The bioethanol production was confirmed by high-performance liquid chromatography (HPLC) analyze.

Graphical Abstract

Keywords:

• CO₂ sequestration
• biodiesel
• bioethanol
• biosorption kinetics
• heavy metals
• Nile red
• Pilot scale
• tannery effluent

Acknowledgments

The authors are thankful to Tamil Nadu State Council for Science and Technology (TNSCST/ S&T Project/VR/ES/01/2016-2017) for finical support and Laboratory facilities provided by Fermentation Lab, Department of Microbiology [DST-FIST Supported Department], School of Biosciences, Periyar University, Salem, Tamil Nadu, India.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors are thankful to Tamil Nadu State Council for Science and Technology [TNSCST/S&T Project/VR/ES/01/2016-2017] for finical support.