*Review* **Role of Microorganisms in the Remediation of Wastewater in Floating Treatment Wetlands: A Review**

#### **Munazzam Jawad Shahid 1, Ameena A. AL-surhanee 2, Fayza Kouadri 3, Shafaqat Ali 1,4,\*, Neeha Nawaz 1, Muhammad Afzal 5, Muhammad Rizwan 1, Basharat Ali 6 and Mona H. Soliman 7**


Received: 6 June 2020; Accepted: 29 June 2020; Published: 10 July 2020

**Abstract:** This article provides useful information for understanding the specific role of microbes in the pollutant removal process in floating treatment wetlands (FTWs). The current literature is collected and organized to provide an insight into the specific role of microbes toward plants and pollutants. Several aspects are discussed, such as important components of FTWs, common bacterial species, rhizospheric and endophytes bacteria, and their specific role in the pollutant removal process. The roots of plants release oxygen and exudates, which act as a substrate for microbial growth. The bacteria attach themselves to the roots and form biofilms to ge<sup>t</sup> nutrients from the plants. Along the plants, the microbial community also influences the performance of FTWs. The bacterial community contributes to the removal of nitrogen, phosphorus, toxic metals, hydrocarbon, and organic compounds. Plant–microbe interaction breaks down complex compounds into simple nutrients, mobilizes metal ions, and increases the uptake of pollutants by plants. The inoculation of the roots of plants with acclimatized microbes may improve the phytoremediation potential of FTWs. The bacteria also encourage plant growth and the bioavailability of toxic pollutants and can alleviate metal toxicity.

**Keywords:** floating treatment wetlands; water; plants; microbes; pollutants
