Municipal wastewater treatment facilities are not specifically designed for treating persistent toxic substances (PTS), released from various industrial sources such as car dismantling, and electronic-waste recycling activities. These toxic chemicals entered into the sewage treatment plants (STWs) through point source discharge and urban runoff. The removal of polycyclic aromatic hydrocarbons (PAHs) and four metals (Chromium (Cr), Copper (Cu), Nickel (Ni) and Zinc (Zn)), the most abundant contaminants detected in the final effluent in our previous study (in Shatin STW and Stonecutters Island STW) and nutrients (Ammonium (NH4+) and nitrate (NO3−)) by wetland plants will be investigated. Three wetland plant species with the best performance in removing pollutants (PAHs, Cr, Cu, Ni, Zn, NH4+, NO3−) will be identified from the local environment via both field and greenhouse experiments. Their resistance to the pests commonly found in Hong Kong wetland plants (e.g. Pomacea canaliculatas (apple snail)) and water level fluctuations will also be studied. River water samples, sediment and plant specimens will be collected for chemical analyses. Bioaccumulation factors (BAFs), biota to sediment accumulation factors (BSAFs) of the four metals and the quasi-equilibrium factor (αpt) of PAHs will be derived from their concentrations in the water, sediment, and plant samples collected from different sites for selecting the most suitable plant community for specific contaminants. The selected wetland plants will be applied in a pilot-scale constructed wetland experiment, and the removal of PTS by different plant associations will be examined in both monoculture and polyculture. The study is expected to raise the interests of general public in wastewater treatment and exchange knowledge with professionals in the field, through publications, seminars and scientific meetings. The present study may also help to provide valuable information for dealing with water pollution problems in fresh water bodies (e.g. rivers and streams) by using constructed wetlands in the nearby region of Pearl River Delta.
|Effective start/end date||01/06/17 → 31/05/19|