Bioaugmented Phytoremediation of Heavy Metals in Petrochemical Wastewater Using Eichhornia crassipes

This study investigated the potential of microbial-assisted phytoremediation using Eichhornia crassipes (water hyacinth) to reduce heavy metal and salinity pollution in produced water collected from Aadi Oil Field in Gujar Khan, Pakistan. Produced water was analyzed for physicochemical parameters and heavy metal content using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) to establish baseline data. E. crassipes plants augmented with indigenous, contaminant-tolerant microbial isolates were employed in a 15-day laboratory experiment. The results showed a resilient growth response, with plant height increasing to approximately 11-15 cm and root length extending up to 10-13 cm across treatments. Biomass also improved, with wet weights reaching 21-24 g from an initial 20 g. The treatment effectively reduced key physicochemical parameters: pH was stabilized from an initial alkaline value of 9.14 to near-neutral values (7.0-7.5), and total dissolved solids (TDSs) were reduced by approximately 50%. Heavy metal removal rates varied, with the highest efficiency of 79.2% for Silver (Ag) and the lowest (18.5%) for Mercury (Hg) This study demonstrates that E. crassipes actively participated in phytoremediation by absorbing and accumulating heavy metals and reducing salinity. The association with contaminant-tolerant microbes appeared to enhance the plant's tolerance and overall treatment efficacy, indicating that plant-microbe interactions offer a sustainable strategy for the treatment of produced water.