Bioremediation of petroleum hydrocarbons by use of freshwater microalgae neochloris aquatica

Abstract

Bioremediation offers a promising solution for restoring contaminated freshwater environments, particularly those polluted by crude oil. Neochloris aquatica (N. aquatica) thrives in freshwater ecosystems, is sensitive to various pollutants, and can be easily cultivated in both liquid and solid media, including open and large-scale ponds. This study aimed to evaluate the bioremediation capacity of N. aquatica in freshwater environments contaminated with Siberian light crude oil (SBO). Cultivation was conducted over a 6-day period in a greenhouse under natural photoperiod conditions, using nutrient media supplemented with varying concentrations of crude oil (0.2%, 0.5%, 1%, and 2% v/v). To assess the degradation performance, extracts were analyzed using GC/MS and synchronous UV fluorescence spectroscopy. N. aquatica exhibited high biodegradation capacity, particularly at low crude oil concentrations. After 6 days of exposure, algae cultivated in media containing 0.2% and 0.5% SBO degraded approximately 83.3% and 55.59% of total aromatic compounds, such as phenanthrene. Similarly, compared to the control at day 6, phenanthrene levels in the 0.2% group dropped by 79.02%, and total n-alkanes decreased from 699.6 mu g/mL to 147.3 mu g/mL. UVF analysis showed a strong negative correlation between total petroleum hydrocarbons (TPH) and exposure time (R2 = 0.98). Biodegradation efficiency of N. aquatica ranged from 14.54% to 76.80% on day 6, depending on oil concentration. These results highlight N. aquatica as a promising candidate for phytoremediation of low-level crude oil contamination in freshwater.