Nutrient Film Techniques (NFT)
An alternative approach to the use of aquatic macrophytes, which was tried exper-imentally, involved growing plants on an impermeable containment layer, in a thin film of water. In this system, the wastewater flowed directly over the root mass, thereby avoiding some of the mass transfer problems sometimes encoun-tered by other aquatic phytotreatment regimes. Though the early work indicated that it had considerable potential for use in the biological treatment of sewage and other nutrient-rich effluents, it does not appear to have been developed further and little is known as to the conditions which govern its successful practical applica-tion. One interesting aspect which did, however, emerge was that the cultivation system could also be extended to most terrestrial plants, which may yet be of possible relevance to the future development of land-based phytotreatments.