Bioremediation of domestic wastewater with microalgae-cyanobacteria co-culture by nutritional balance approach and its feasibility for biodiesel and animal feed production

Nongmaithem Debeni Devi, Xiao Sun, Bo Hu, Vaibhav V. Goud

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30 Scopus citations

Abstract

Microalgae have been identified as a promising option for concomitant bioremediation of wastewaters and biodiesel generation. However, the nutritional composition of wastewater differs between locations, and some wastewater contains low nitrogen levels that inhibit microalgae growth, resulting in poor total nutrient removal and biomass output. Furthermore, the high cost of harvesting microalgae biomass is a barrier to commercial microalgae farming. This study aims to employ a novel microalga, Scenedesmus sp. DDVG I for bioremediation of low-nitrogen domestic wastewater. The nutritional balance of the wastewater was achieved with the addition of urea at two different levels and then was used for the cultivation of microalgae. The results showed that the optimized nutritional condition included total nitrogen (TN) of 250 mg/L and total phosphorus (TP) of 5 mg/L (N250/P5). The culture cultivated in this optimal medium improved chemical oxygen demand (COD), TN, and TP removal by as much as 89.5 %, 99.98 %, and 99.1 %, respectively. Scenedesmus sp. DDVG I growth was likewise at its peak, with a value of 5.1 g/L, but with a low harvesting efficiency (0.02 %). Subsequently, Scenedesmus sp. DDVG I was co-cultured with a novel cyanobacterium, Limnothrix sp. DDVG II under the optimal nutritional condition. The results revealed a 99.5 % increase in harvesting efficiency with effective wastewater treatment. The co-culture-derived biodiesel also complied with the standard specifications. Further, analysis of the essential amino acid content and in vitro digestibility of the biomass proved its usefulness as a feed supplement. Overall, this study demonstrated a promising future for a cleaner environment and sustainable bio-economy of microalgae.

Original languageEnglish (US)
Article number140197
JournalChemical Engineering Journal
Volume454
DOIs
StatePublished - Feb 15 2023

Bibliographical note

Funding Information:
The authors would like to thank the School of Energy Science and Engineering, Department of Bioscience and Bioengineering, Indian Institute of Technology Guwahati, and Department of Biosystems and Agricultural Engineering, University of Minnesota for providing analytical facilities. The authors are also thankful to the Ministry of Education, Government of India for financial assistance.

Publisher Copyright:
© 2022 Elsevier B.V.

Keywords

  • Consortium
  • Feed supplement
  • Limnothrix sp.
  • Lipid
  • Scenedesmus sp.
  • Wastewater treatment

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