POLLUTION REDUCTION POTENTIAL OF SUBSURFACE FLOW CONSTRUCTED WETLAND SYSTEM

Abstract

Wetlands have been used as a potentially cost-effective secondary waste water treatment system to treat the waste water before discharge into the water bodies. The aim of this study was to compare the pollution reduction ability of plant species at various depths in a constructed wetland system. Two different grass species such as Eleucine indica (Goose grass), Dactyloctenium aegyptium (Crowfoot grass) and a sedge namely Cyperus iria (umbrella sedge) and the control without any plant species were introduced in the constructed wetland system. The system was operated continuously by inlet valve from tank filled with storm water. Physicochemical parameters such as pH, DO, BOD, TS, Nitrate and Phosphate contents were measured in one week interval using standard procedures. The results revealed that the pollution reduction ability was very high in Cyperus iria at one foot depth whereas the nitrate and phosphate reduction ability was comparatively high in Cyperus iria at their 1.5 feet depth.