*3.2. Buoyancy*

In FTWs, di fferent materials have been applied with di fferent natural buoyancies. These floating materials serve as a platform to fix the plants. The floating mats are made up of di fferent materials such bamboo sticks, polyester fibers, plastic and foaming sheets [57–59]. The floating material should be hydrophobic, nutrient absorbent, bacterial adhesive, and with no desorption [15].

Some patent floating mats are also available commercially, such as Beemat ®, and Bioheaven ®, made up of buoyant material with holes for plantation. The wrapped plastic tubes and pipes manufactured from polyethylene (PE), polypropylene (PP) and polyvinyl chloride (PVC), and PS (polystyrene) foams are most commonly used for the construction of floating frames and rafts [38]. A natural buoyant material, bamboo, has been found to be a cheap and cost-e ffective material for the construction of floating rafts [60].
