Criteria for determining alternative plants to improve the resource recovery efficiency in constructed wetlands

The aim of this study is to find the macrophytes that possess high resource recovery efficiency in subsurface-flow constructed wetlands (SFCWs) while not pose any negative effects to the treatment performance. Five criteria were included in this analysis. The suitable alternative plants were proposed according to their availabilities in each climate zone. For their potentials as an energy sources, they are related to plants' productivity as well as growth rate. Concerning the utilization options, plants that possess high economical value and/or versatilities were encouraged. Among the options are handicrafts, fertilizers, animal feeds, construction materials, paper making, and pharmaceutical products. In term of nutrient uptakes, in most cases they were relatively minor comparing to other removal mechanisms in SFCWs. No significant differences in term of treatment efficiency could be found. The proposed species have to be able to tolerate the municipal wastewater. The cost differences of plant propagules between each species are marginal, hence they should not be considered as the main selection criteria. Based on an investigation of 45 species worldwide, the recommendation table is developed with 13 suitable species that fit all the criteria. It appears that there are more than one "most appropriate plant species" in each climatic region. To perform the selection, the operators should weight their preferences on each criteria and the availability of plants in the area.