Abstract
Bioremediation technologies using high biomass aquatic weed species are applicable to clean-up waste water in constructed wetland for its reuse in agriculture. A rectangular sub surface horizontal model of 4’x 2’x 1’ was developed for removal of pollutants such as nitrates, phosphates and heavy metals in waste water. Gravels of 1.5-3”, 0.5-1” and 0.37-0.5” size were used as a media in the treatment zone in which the rhizomes of Arundo donax were planted. After well spreading of roots entangled with media in a bed zone, a treatment of drain water was given. Prior to the treatment, the average pollutant concentration of nickel, copper, nitrates and phosphates in drain water were 320, 340, 500, 35 ug/L respectively which were beyond the prescribed limit for irrigation. As compared with the untreated waste water, the rhizofilter model performed in reduction of the concentrations of nickel, copper, nitrate and phosphate to the extent of 55.8, 40.6, 70.0 and 42.8 per cent respectively after the treatment. As far as water flow through gravel medium is concerned, no clogging was occurred in treatment zone resulting free discharge of water through the outlet. The characters of exuberant root and good adaptability of Arundo donax suggested its potential in rhizofiltration of waste water. Thus, reed based treatment of waste water can be applied for treatment of drain water on field scale for irrigation purposes vis-à-vis as a preventive measure to check nitrate and phosphate related problems of weed infestation in surface water bodies.