Performance Evaluation of Aquatic Macrophytes for Municipal Wastewater Treatment

Abstract

Municipal Sewage of Taxila was selected for evaluation and comparison of the performance of three aquatic macrophytes regarding sewage treatment. A bench scale laboratory model was developed and used for experimentation. Six experimental runs were conducted and each run laps over thirty (30) days. In each experimental run continuous monitoring of municipal sewage was done for each macrophyte specie. The aquatic macrophyte species used for the performance comparison were Water Hyacinth, Duckweed & Water Lettuce. For performance comparison four parameters including BOD 5 , COD, Nitrogen and Phosphorus were selected. These parameters were monitored for both the influent and effluent sewage samples. During the entire study, the average reduction of 51% for BOD 5 , 47% for COD, 19% for phosphorus, and 41% for nitrogen were found with water hyacinth. When the same sewage was treated with Duckweed the values came out to be 34% for BOD 5 , 27% for COD, 16% for phosphorus and 18% for nitrogen. Similar trend was observed in the experiments with Water Lettuce as 33 % for BOD 5 , 29% for COD, 11% for phosphorus and 15% for nitrogen. Sewage treatment in macrophyte based system included both the anaerobic & aerobic microbial processes. The treatment is further followed by chemical conversions, sedimentation & volatilization. The highest pollutant removals were observed for at temperature range of 15-38 o C and at pH variation between 6 and 9. In developing countries like Pakistan, where no importance is being given to municipal sewage treatment, the method found to be environmentally and financially sustainable.