Aquatic plants for the tertiary treatment of wastewater

Abstract

Much literature is available on the use of aquatic plants in the treatment of wastewater. However, since conditions for plant growth differ from place to place, it is necessary to establish the effectiveness of t h i s type of treatment for each locali y. A programme to test the effectiveness of aquatic plants in improving the quality of secondary effluent from a wastewater treatment plant near Perth was conducted for twelve months. Eleven ponds, each of 10 cubic metres capacity, were constructed at the plant and were continuously supplied with secondary effluent. Three plant species were established in the ponds. Lemna sp.(Duckweed), Myriophyllum aquaticum (Parrot's Feather or Water Milfoil) and Typha orientalis (Bullrush) and some ponds were left without macroscopic plants. Lemna and Myriophyllum were harvested weekly and the results of both plant analysis and water analysis in the ponds indicated substantial nitrogen reduction in the tertiary effluent.