Potentiality of Azolla pinnata R. Br. for Phytoremediation of Polluted Freshwater with Crude Petroleum Oil

The pollution of freshwater resources with crude petroleum oil is a major environmental issue in oil-producing countries. As a result, the remediation of polluted aquatic ecosystems using eco-friendly and cost-effective technology is receiving increased global attention. In this study, the ability of Azolla pinnata R. Br. to remediate petroleum-polluted freshwater was assessed. The remediation potentiality was determined by evaluating the total petroleum hydrocarbon degradation percentage (TPH%) and changes in the molecular type composition of saturated and aromatic hydrocarbon fractions. TPH% was estimated gravimetrically, and changes in the molecular type composition of saturated and aromatic fractions were measured using gas chromatography and high-performance liquid chromatography, respectively. The results reveal that A. pinnata has the potential to phytoremediate freshwater polluted with low levels (up to 0.5 g/L) of petroleum hydrocarbons (PHs). After seven days of phytoremediation, the degradation rate of total PHs was 92% in the planted treatment compared with 38% in the unplanted positive control. The highest breakdown of PHs for the normal paraffinic saturated hydrocarbon fraction occurred in the presence of A. pinnata combined with Anabena azollaea (A-A), which showed a moderate degradation capacity toward total aromatic hydrocarbons (TAHs) and total polycyclic aromatic hydrocarbons (PAHs). The results indicate that A. pinnata effectively removed C18, a saturated PH, and acenaphthene (Ace), an aromatic PH. Therefore, this study suggests that A. pinnata is a useful tool for the remediation of freshwaters contaminated with low pollution levels of crude oil.

Automated summary

The study found that Azolla pinnata has the potential to remediate freshwater polluted with low levels of petroleum hydrocarbons, with the best degradation results achieved when combined with Anabena azollaea.