SELECTION OF SUITABLE PLANT SPECIES FOR WASTEWATER TREATMENT BY CONSTRUCTED WETLAND AT THE FORMOSA HA TINH STEEL COMPANY

Abstract

The study aimed to select suitable plant species in constructed wetland at Formosa Ha Tinh steel company and identify proper nutrient supplements for these plants growth. The tolerance of different aquatic plant species was tested with treated wastewater. Phragmites australis (Cav.), Typha angustifolia L. and Cyperus tegetiformis were selected for vegetation. In this experiment, removal efficiencies for monitored chemical parameters were in the range of 26.5 – 91.7 %, while elimination rates of total coliform were about 50 %. In the beginning, the plant nutrient demand for the first 3 months estimated based on theoretical mean annual nutrient uptake was 495 kg N, 153 kg P and 36 kg K per ha. When the wastewater entered CWs, the available nutrients in the influent could be enough for the plants growth. In fact, observations of the health status of the plants would serve as a basis for the fertilizer feeding decision, the concentration of mineral nutrients available in the wastewater are very important.