## 1 Introduction  
The petrochemical industry is one of the main sources of hydrocarbon contamination in water. The high level of hydrocarbons in the aquatic environment is mainly due to continuous advancements in the exploration and extraction of oil [(1)]. The wastewater generated by the petroleum industry contains high contents of one of the classes of hydrocarbons known as polyaromatic hydrocarbons (PAHs) [(1; 2; 3; 4)]. Among the different PAHs, phenanthrene is a common wastewater contaminant [(2; 5; 6; 7; 8; 9)]. It comprises three benzene rings and is persistent in the environment due to its high molecular weight, chemical stability, and hydrophobic nature [(10; 11)]. It has been found to be toxic to fish, crustaceans, gastropods, mussels, and marine diatoms [(12; 13)].  
Over the years, various conventional methods such as advanced oxidation, active carbon absorption, photocatalysis, electrolytic and electro-irradiated technologies, Fenton-based advanced oxidation processes, ozonation, and pulsed dielectrics have been reported for the handling of phenanthrene-contaminated water [(6; 14)]. However, these conventional technologies based on physicochemical methods are not sustainable due to their higher operational cost and environmental incursions as well as the requirements for engineering skills, labor management, and operational supervision [15; 16]. FTWs and CWs have shown to be a promising approach for the management of contaminated water. An FTW is a hydroponic system that provides a medium to facilitate plant growth [17; 18; 19]. CWs are products of environmental engineering skills that are built by adopting and performing processes of natural wetlands through vegetation, soil, and associated microbes in a controlled environment for the purpose of wastewater treatment [9; 20]. FTWs are easily handled, imitate a natural habitat, and are a low-cost technique when compared with CWs whereas CWs provide a multi-layer medium for the remediation of contaminated water and a significant physical support for plant growth. In FTWs and CWs, plant-associated microorganisms play an important role in the remediation of water contaminated with organic pollutants [21; 22; 23]. In wetlands, vegetation plays an important role in the remediation of contaminated water. Different plant species with ornamental characteristics and an ability to withstand unfavorable and harsh conditions are used. The most commonly used flowering species are _Typhu, Canna, Iris, Heliconia,_ and _Zantedeschia_[24]. However, the occurrence of organic pollutants such as hydrocarbons inhibits plant growth and ultimately the population and performance of plant-associated indigenous microorganisms. To overcome this issue, the augmentation of microorganisms capable of degrading pollutants, and with plant growth-promoting (PGP) activities, has been employed in FTWs and CWs to improve the phytoremediation process [23; 25; 26]. Although bacterial-augmented FTWs and CWs can efficiently remove hydrocarbons from the water, their efficiency has never been compared for the remediation of PAH-contaminated water [27; 28].  
The present study aimed to compare the potential of FTWs and CWs vegetated with _Phragmites australis_ and inoculated with a bacterial consortium to remove phenanthrene from water. Reductions in the phenanthrene concentration, COD, BOD, and toxicity level of the water were determined. The bacterial perseverance in the water, roots, and shoots of the plants as well as the growth of the plants vegetated in the FTWs and CWs were assessed.