**8. Conclusion and future directions**

For the phytoremediation of radioactive waste, screening of the appropriate plant type is the utmost important. Diverse factors such as radioactive waste characteristics, the concentration of a target radionuclide in the radioactive waste, the biomass of the plant, the plant species and plants composition in the radioactive waste dumped area, the concentration of a target radionuclide in the plant, and should be examined thoroughly.

The PF concern the concentration of a goal element in a plant, the shoot biomass, and the concentration of the target element in the tailings or tailing (root) of the plant, was planned for the target element to specify the removal capability of the plant from the radioactive waste. Using the PF as the criteria, *P. australis*, *M. cordata*, and *Azolla imbricata* were selected as the contenders for phytoremediation of uranium-contaminated soil, *P. multifida* was particular as the aspirant for phytoremediation of 226Ra-contaminated soil, and *P. australis* was designated as the contestant for phytoremediation of thorium-contaminated soil.

Further advances must be made in the application of environmental remediation to selectively eradicate materials, the concentrations of chemicals present in the contaminated water, have a higher resistance to changes in pH, greater stability for a longer period of time and cost effectiveness.

Sensors have been established for detecting gases, chemicals and volatile organic compounds (VOCs), and the detection and identification of radiations. Further growth is essential in the functional properties of nanomaterials to meet the requisite for trace detection and the treatment of pollutants in soil, water and air and important fundamental and mechanistic studies are required in order to fully explore their real potentials. The CNTs/metal oxide are promising constituents in ecological pollution management at a bigger prospective for practical applications.
