LAUSR

Climate change not only intensifies eutrophication and enhances the rainfall, but also elevates the contents of greenhouse gases, which can further increase the intensity and frequency of extreme precipitation events. The effectivity of phytoremediation of urban wastewaters by water hyacinths under an extreme rainfall event (up to 380 mm d-1) was investigated using self-designed fabrications with six flow rates (2-15 m3 d-1) in situ on pilot scale for 30 days. The results suggest that water hyacinths had high N and P removal capacities even under adverse conditions such as low dissolved oxygen concentrations (DO, <1 mg L-1) and high ammonium concentrations (NH4+-N, >7 mg L-1). Specifically, the highest removal yields of N and P were 13.14 ± 0.47 g N·m-2·d-1 and 2.12 ± 0.04 g P·m-2·d-1, respectively. The results indicate that water hyacinths can be used for water treatment to reduce the amounts of NH4+-N, dissolved organic nitrogen (DON) and phosphate (PO43-) even during extreme precipitation events. Moreover, DO increased due to wet deposition, runoff and surface flows during the extreme rainfall event, resulting in shifts between nitrification and denitrification processes which significantly altered nitrogen forms in urban wastewater. Results of this study suggest that water hyacinths could be recommended as a cost-effective and eco-friendly technology for urban wastewater phytoremediation in areas suffering from frequent extreme precipitation events.