Use of climbing and ornamental plants in vertical flow constructed wetlands treating greywater

Abstract

This study focuses on the use of climbing ornamentals and ornamental plants for greywater treatment in vertical flow constructed wetlands. Different design parameters, such as substrate (sand or vermiculite), the use of saturation zone, and plant species (Trachelospermum jasminoides, Lonicera japonica, Callistemon laevis) were evaluated for optimal removal of studied pollutants. Results revealed that, regarding the tested substrates, sand with or without saturation zone presented significantly higher removal rates for turbidity (94 ± 5 %) and Chemical Oxygen Demand: (96 ± 7 %) than vermiculite (Turbidity: 54 ± 23 %; Chemical Oxygen Demand: 73 ± 29 %). Moreover, slightly higher removal rates were recorded in vegetated systems compared to unvegetated systems. According to the findings, all examined plants survived and grew in vertical flow constructed wetlands receiving up to 204 mm of greywater per day. However, L. japonica and C. laevis are more well-adapted to such constructed wetland systems compared to T. jasminoides. Overall, the application of climbing and ornamental plants in vertical flow constructed wetlands for greywater treatment in buildings seems like a very promising option to improve the aesthetic appearance of the systems and consequently increase public acceptance.