Abandoned reverse osmosis membrane effects on phytoremediation of saline soils with trees

We used two common species of tree, Ailanthus altissima S. and Ulmus pumila L., as the model plants to study the behavior of abandoned reverse osmosis (RO) membrane on the phytoremediation of saline soil following a pot experiment of up to 3 years. Plants (control) or plants with the roots wrapped by abandoned RO were cultivated in pots filled with saline soil, and irrigated twice a week with tap water. Data from dry weight, tissue levels of mineral nutrients, chlorophyll (Chl), leaf protein content and content of potential toxic element (Na+) showed that the abandoned RO significantly influenced the growth and development of the plants. A dramatic improvement of the leaf, branch and trunk biomass of A. altissima S. and U. pumila L. was observed in this study. Subsequently, the enhanced uptake of N, P and K+, and decline of Na+ accumulation in the leaves, branches and trunks of A. altissima S. and U. pumila L. are suspected to be largely due to biological filter functions of the abandoned RO. In addition, Chl and protein contents were significantly (P < 0.05) improved in both plant species treated with abandoned RO. These findings indicated that abandoned RO application could be highly beneficial for the cultivation of tree plants such as A. altissima S. and U. pumila L. in saline soil. Hence, the application of RO to both plant species can be used as a phytoremediation technique, although A. altissima S. appears to be more suitable for the phytoremediation of saline soil.