Heavy Metal Scavenging Potential of Indigenous Microalgae of Bangladesh: A Study on its Application in Textile Effluent Treatment

Aims: The study aimed to identify the physicochemical property improvement and heavy metal scavenging potential of indigenous microalgae (Spirulina sp. and Chlorella sp.) of Bangladesh for treatment of textile wastewater disposed in the open environment.

Study Design: The capacity of improving the water quality of the textile effluent by heavy metal absorption was assessed. The quantitative determination included the comparison of physical characteristics (pH, TDS, EC, DO, COD) and heavy metal profile (Cr, Cd, Pb, Zn, Fe) of the textile effluent before and after bioremediation. Effluent treatment was carried out by individual species separately and in combination with both for a total of 25 days.

Place and Duration of Study: Major experiments were carried out at the Applied Botany Laboratory, Dhaka Laboratory, BCSIR, Dhaka, Bangladesh from January 2022 to February 2024. Quantitative estimations were carried out at Soil & Water Laboratory, Dhaka Laboratory, BCSIR, Dhaka, Bangladesh.

Methodology: The textile wastewater was characterized using physicochemical parameters and heavy metal concentration before the experimental procedure. Three treatment plans were designed, two (TCV and TSP) using individual species separately and one treatment (TC) using both species in combination. The treatment continued for 25 days. The physicochemical parameters and heavy metal concentration of the treated effluent were measured at 5 day intervals till the 25th day of the experiment. Comparative analysis of the data was utilized to determine useful species for further applied studies in future.

Results: The Chlorella treatment achieved remarkable pH restoration, with a peak of 7.94 on Day 10 and stabilization at 7.28 by Day 25. Moreover, the same treatment exhibited substantial reductions in TDS, dropping from 7750 mg/L to 455 mg/L by Day 10, and further to 301 mg/L by Day 25. Additionally, it effectively reduced heavy metal concentrations; Cr from 0.783 ppm to 0.462 ppm by Day 25, well below permissible limits.

Conclusion: The comparative data suggested the overall improvement of the effluent quality can be achieved by a combined treatment of C. vulgaris and S. platensis, quickly and cost-efficiently. Further investigation is required for an in-depth understanding of their combined potential.