Screening of Microalgae and Diatoms from Jayanti K Rao Drain and their Role in Wastewater Remediation

Abstract

The microalgal flora of the Jayanti K Rao drain in Kharar was studied in untreated wastewater sample (A) collected at the start point, and the treated sample (B) collected at the end of the drainage. In the untreated sample, no specific algae were dominant, the total cell count of unicellular microalgae, including diatoms, was 4×10⁶cells/mL, whereas in the treated sample, Scenedesmus sp., Chlorella sp., and diatoms were found to be dominant, with a total cell count of 2.5×10⁷ cells/mL. Principal component analysis (PCA) analysis clearly showed a biological shift from untreated to treated wastewater. Pure culture isolation of Chlorella sp. and Scenedesmus sp., were done after enrichment in BG-11 media, whereas Navicula sp. was isolated in F/2 media specific for diatoms. A mixed culture of Chlorella sp., Scenedesmus sp., and diatoms was grown in 3 different media supplemented with 3 different silica sources, with and without CO2 sparging. DM medium with Na2SiO3 and CO₂ sparging gave the maximum biomass (37.08mg), followed by WC Na2SiO3 plus CO₂ sparging (28.67 mg). Minimum biomass was in F/2 media Na2SiO3 (2.02mg), followed by WC media SiO₂ G (2.33mg). CO₂ sparging successfully enhanced algal growth and biomass production under pure culture conditions. Parameters like pH, Dissolved Oxygen (DO), Total Dissolved Solids (TDS), and Electrical Conductivity were measured in samples A and B. The pH value changed from 7.46 to 7.43, while TDS changed from 1108 to 1027 mg/L, and conductivity changed from 781 to 730 µS/cm. The increase in DO from 5% in sample A to 13% in sample B clearly shows improvement of water quality and its remediation by dominant microalgal species such as Scenedesmus sp., Chlorella sp., and diatoms.