Abstract: The use of constructed wetlands in dye wastewater treatment is still at experimental stages. The extreme values of pH and pollutants in dye wastewater often kill plants and microorganisms in wetlands. This paper aims to understand the treatment efficiency of Free Water Surface (FWS) constructed wetland built for the effluents of dyes industry in Gadoon industrial estate, Pakistan. A total of 192 samples from dye wastewater, wetland’s influents and effluents were analysed for the relevant physico-chemical and biological parameters for two years. During the first year of monitoring the size of wetland was 5700 m2 and its efficiency was tested for specific pollutants. In the second year the wetland was redesigned and extended to 6307 m2 and its efficiency was determined for heavy metals, solids, anions, BOD and COD. High concentrations of physico-chemical and biological parameters were measured in the dye wastewater during both periods of evaluation. However, results demonstrate that the wetland retained promising quantity of heavy metals, anions, solids and COD from wastewater and also increases the pH in the system. The study suggests that strategic designed FWS constructed wetland can effectively handle highly polluted dye wastewater.
Keywords: Natural treatment systems; Industrial wastewater; Removal of pollutants; Free water surface wetland