Use of water hyacinth for removal of pollutants in sewage

Abstract

The study is an experimental investigation into the use of water hyacinth for removal of pollutants in sewage. This system is considered as low cost technology, alternate to conventional treatment system for sewage treatment in hot climates. Cost estimates for sewage treatment in ponds system using water hyacinth and. without water hyacinth is compared. Ponds with water hyacinth has been found cheaper than conventional treatment system. From the literature review it was apparent that little work had been carried out on pollutant removal process from sewage using water hyacinth. The shallower depths and the presence of water hyacinths in place of algae are the major differences between treatment systems with water hyacinths and stabilization ponds. The' water hyacinths, themselves, bring about little actual treatment of the waste water. Their function is to provide components of the aquatic environment that improve the waste water treatment capability and/or reliability of that environment. Survival and growth rate of water hyacinth were observed, when this plant was grown on sewage. Longer type water hyacinth is seen continue to survive in sewage having maximum initial BODs of" 110 mg/l. Evapotranspira-t:ion and Evaporation rate from sewage with and without water hyacinths were determined in various conditions. Three types of water hyacinths were used to determine evapotranspiration rate from different concentration of sewage sample. Evaporation rate from sewage sample were determined in similar condition to evapotranspiration test. Evapotranspiration rate is seen 2 to 4.5 times higher than evaporation rate in the similar condition. Characterization of pollutant removal from sewage with water hyacinth were done in various conditions primary importance was given to findout the removal performance of organic loadings, suspended solids (ss) and Nutrient Concentration (P&N). Higher pollutants removal rate have been found in case of sewage treatment with water hyacinth than without water hyacinth. In general removal of organic matter in water hyacinth system is 8- 15% and removal of other pollutants are 10-25% greater than without water hyacinth system.