Waste Water Purification Using Locally Available Aquatic Plants

Abstract

The primary objective of this study was to evaluate the performance of two different aquatic macrophyte for treatment of municipal waste water collected from Colombo 15. A physical model of a treatment plant was constructed and was operated for four experimental runs. Every experimental run consisted of a fourteen day period. Locally available macrophyte species (Water Hyacinth and Duckweed) were selected for testing. To evaluate the each macrophyte, BOD, COD, Plant growth monitoring, Bio-mass production, PH values and Temperature were monitored. The average reduction values for each parameter, using Water Hyacinth, was 57.64% for BOD, 55.85% for COD, 34% reduction of BOD at a Temperature of 25-35 CO, 41% reduction of BOD at a PH value of 6.5-8.5.For Duckweed, the average removal efficiency for the selected parameters were 51.53% for BOD, 31.53% for COD, 20%> reduction of BOD at a Temperature of 25-35 °C, 23% reduction of BOD at a PH value of 6.5-8.5.A significant growth of plant biomass was measured within the first two weeks of the first run. It was also observed that performance of macrophytes (Duckweed and Water Hyacinth) is_ influenced by variations in pH and temperature. A PH level of 6.5-8.5 and temperature of 25-35 °C is most favourable for treatment of waste water by macrophytes. When considering all the water quality parameters which were tested Water Hyacinth has the better and more superior waste water purification efficiency when compared to Duckweed.