Influence of plant species and submerged zone with carbon addition on the removal of metals by stormwater biofilters

Abstract

The metal removal in stormwater biofilters may be influenced by the type of vegetation and the presence of a submerged zone (SZ) with carbon (C) addition under wet-dry seasonal climatic patterns. A glasshouse experiment using two plant species (Baumea juncea and Melaleuca lateritia) with/without SZ and C addition, and three planting treatments (Baumea rubiginosa, Juncus subsecundus, and no-plant as control) with SZ and C addition was conducted to investigate the metal removal from the stormwater in biofilter columns. After 20 months of growth, plant growth was better in the presence of SZ than absence. The removal of copper (Cu) and lead (Pb) significantly increased in the biofilters with SZ, but Zn removal was not significantly influenced regardless of type of vegetation. Although the metals accumulated differently in the various plant species, it was not possible to discriminate relative performance in terms of metal removal among the plant species. Dissolved oxygen (DO) and pH in the outflows were significantly influenced by the type of vegetation and the presence of SZ. Hence, further study is needed to elucidate the different adsorption and retention of metals in media in relation to variations of redox and pH in biofilters under wet/dry seasonal climatic patterns. Furthermore, studies under the field conditions are needed to verify the findings.

Keywords:

• Bioretention systems
• Metal
• Plant growth
• Wastewater
• Wet/dry season

Acknowledgments

The study received financial support from Department of Water, Western Australia. We thank Mr. Michael Smirk for instruction and help with laboratory analysis, and Mr. Kosta Voltchanskii and Ms. Ping Jiang for helping with glasshouse work and laboratory analysis.