Removal of Pyrene from Soil Using Phytobioremediation (Sorghum Bicolor-Pseudomonas)

Polycyclic aromatic hydrocarbons (PAHs) are a recalcitrant group of contaminants, known to be highly persistent in the environment. Most of these compounds are persistent pollutants in the soil.
This study aimed to investigate the use of Pseudomonas aeruginosa and Sorghum bicolor in improving phytoremediation of soil contaminated with pyrene.
During 3 months of the experiment, soil samples were collected and analyzed once a month to determine the pyrene removal rate. After the experiment, the plant biomass was measured, and the number of bacteria in the rhizosphere was counted.
The results showed that pyrene removal rate was 35 - 47% in the unplanted treatment. Use of Sorghum bicolor alone reduced soil pyrene by 53 - 70%, whereas the combination of this plant with Pseudomonas bacteria reduced pyrene by 66 - 82%. Moreover, the number of bacteria in the rhizosphere and pyrene removal rate significantly increased in the planted treatments, compared to the unplanted treatment.
Based on the findings, root exudates and Pseudomonas bacteria through stimulation of root development could increase the number of bacteria and enhance the efficiency of pyrene removal. Therefore, combination of phytoremediation with bioremediation can be a suitable alternative for remediation of pyrene-contaminated soils.