STUDIES ON TREATMENT OF WASTEWATER BY WATER HYACINTH

Abstract

Wastewater treatment has been the focus of attention for a number of years with the aim of developing waste stabilization systems which are simple, economical, energy efficient and require low operation and maintenance costs. Towards this for sometime, use of water hyacinth (EICHHORNIA CRASSIPES), a vascular aquatic plant, has also been introduced for wastewater treatment particularly for treatment of pretreated wastewaters and for upgrading effluent treated by stabilization ponds. Its advantages have been rapid growth rate, low cost and simplicity of operation and maintenance. Experiments conducted in the past with batch-mode of opera-tion both with and without water hyacinth in a temperature range of 22°C to 33°C have shown additional removal of COD and TS by 17 and 11 percent respectively. In the present study employing water hyacinth, removal of COD etc. has been observed using synthetic waste, shallow can model ponds and continuous mode of operation. Two runs each lasting for 17 days duration were carried out on synthetic wastewater having initial COD of 600 mg/1 in conti-nuous mode of operation. The ponds were operated at different hydraulic retention times (2 to 10 days) both with and without hyacinth under ambient air temperature range of 4°C to 22°C. On the basis of analysis of experimental data it was concluded that water hyacinth ponds provide additional removal of COD and total solids by about 9.5 to 11% with hydraulic retention times between 2 to 10 days even at Low temperatures as may be occurring during the winter months, removal of COD was observed between 51.00 to 84.5 percent for detention time 2 days to 10 days.