*Cyperus laevigatus* **L. Enhances Diesel Oil Remediation in Synergism with Bacterial Inoculation in Floating Treatment Wetlands**

**Muhammad Fahid 1,2, Shafaqat Ali 1,3,\*, Ghulam Shabir 2, Sajid Rashid Ahmad 4, Tahira Yasmeen 1, Muhammad Afzal 2,\*, Muhammad Arslan 5, Afzal Hussain 1, Abeer Hashem 6,7, Elsayed Fathi Abd Allah 8, Mohammed Nasser Alyemeni 6 and Parvaiz Ahmad 6,9**


Received: 20 January 2020; Accepted: 3 March 2020; Published: 18 March 2020

**Abstract:** Diesel oil is considered a very hazardous fuel due to its adverse e ffect on the aquatic ecosystem, so its remediation has become the focus of much attention. Taking this into consideration, the current study was conducted to explore the synergistic applications of both plant and bacteria for cleaning up of diesel oil contaminated water. We examined that the application of floating treatment wetlands (FTWs) is an economical and superlative choice for the treatment of diesel oil contaminated water. In this study, a pilot scale floating treatment wetlands system having diesel oil contaminated water (1% w/v), was adopted using *Cyperus laevigatus* L and a mixture of hydrocarbons degrading bacterial strains; viz., *Acinetobacter* sp.61KJ620863, *Bacillus megaterium* 65 KF478214, and *Acinetobacter* sp.82 KF478231. It was observed that consortium of hydrocarbons degrading bacteria improved the remediation of diesel oil in combination with *Cyperus laevigatus* L. Moreover, the performance of the FTWs was enhanced by colonization of bacterial strains in the root and shoot of *Cyperus laevigatus* L. Independently, the bacterial consortium and *Cyperus laevigatus* L exhibited 37.46% and 56.57% reduction in diesel oil, respectively, while 73.48% reduction in hydrocarbons was exhibited by the joint application of both plant and bacteria in FTWs. Furthermore, microbial inoculation improved the fresh biomass (11.62%), dry biomass (33.33%), and height (18.05%) of plants. Fish toxicity assay evaluated the e ffectiveness of FTWs by showing the extent of improvement in the water quality to a level that became safe for living organisms. The study therefore concluded that *Cyperus laevigatus* L augmented with hydrocarbons degrading bacterial consortium exhibited a remarkable ability to decontaminate the diesel oil from water and could enhance the FTWs performance.

**Keywords:** floating treatment wetlands; *Cyperus laevigatus* L; diesel oil; plant-bacteria synergism; toxicity
