Removal of environment relevant bisphenol A concentration from the contaminated waters using freshwater pond grown...

Bisphenol A (BPA), even at environmentally relevant concentration, exerts toxic effects on aquatic organisms and it requires sustainable removal strategies. Microalgae immobilization in substrate is an emerging technology for bioremediation with less practical implacability due to the high production cost of microalgae. Hence in the present study, microalgae present in the freshwater pond was grown attached to the synthetic substrates for four weeks and utilized for bioremediation. The biofilm, predominantly composed of Merismopedia sp., Cymbella sp., Nitzschia sp., Oscillatoria sp., and Pediastrum sp. was used to treat water samples spiked with environmentally relevant BPA concentration (0.015 ppm; recorded from Ganga River water, India by our team). Higher BPA concentrations (0.15, 1.5 and 15 ppm) were also used to document the toxic effect of BPA on microalgae biofilm. Results showed that microalgae biofilm removed 52.78 ± 2.38 % of BPA from the water contains 0.015 ppm concentration with a low toxic effect on growth and viability of the microalgae. Among which, microalgae biofilm accumulated 33.3 % of added BPA via adsorption and absorption, a significant portion of BPA also been removed by photo degradation and other process of degradation. The conductivity of the water significantly influenced the BPA removal efficiency of microalgae biofilm. As BPA concentration increased, the removal efficiency declined and exert toxic effect on microalgae biofilm growth and viability. The 120 h BPA exposure reduced the microalgae abundance in all treatments. The species like Nitzschia sp., Fragillaria sp. and Merismopedia sp., showed maximum reduction and the Coelastrum sp., Amphora sp., Phormidium sp., Phacus sp., Gomphonema sp. and Scenedesmus sp. showed tolerance towards BPA exposure. These findings highlight the potential of pond grown microalgae biofilm as a practical and eco-friendly solution for removing BPA from contaminated water, particularly at environment relevant concentrations.