Impact of the combined effect of seawater exposure with wastewater and FeO nanoparticles on Chlorella vulgaris microalgae growth, lipid content, biochar, and bio-oil production.

Microalgae is one the promising source of energy for the production of biofuel and other value-added products to replace the existing conventional fossil fuels. However, low lipid content and poor cell harvesting are the key challenges. Based on the growth conditions the lipid productivity will be affected. The current study examines the mixtures of both wastewater and NaCl on the microalgae growth was studied. The microalgae used for conducting the tests were Chlorella vulgaris microalgae. Mixtures of the wastewater was prepared under the different concentrations of the seawater, classified as S0%, S20%, and S40%. The growth of microalgae was studied in the presence of these mixtures, and the addition of FeO nanoparticles was included to stimulate the growth. The results showed that increasing the salinity in the wastewater resulted in decreased biomass production, but significantly increased lipid content compared to S0%. The highest lipid content was recorded at S40%N with 21.2%. The Highest lipid productivity was also witnessed for S40% with 45.6 mg/Ld. The cell diameter was also found to increase with increasing salinity content in the wastewater. The addition of FeO nanoparticles in the seawater was found to enhance the productivity of the microalgae extensively, resulting in 9.2% and 6.15% increased lipid content and lipid productivity respectively compared to conventional cases. However, the inclusion of the nanoparticles slightly increased the zeta potential of microalgal colloids, with no noticeable effects on the cell diameter or bio-oil yields. Based on these findings, Chlorella vulgaris was identified as a suitable candidate for treating wastewater with high salinity exposure.