Performance studies of constructed wetlands for treatment of wastewater under temperate climatic conditions

Abstract

Phytoremediation also known as constructed wetlands is an effective method of treatment of municipal as well as industrial wastewater. The efficacy of this method has already been tested in European and American countries and found to be the best method of wastewater treatment. Efforts have been made in the present work to check the efficacy of phytoremediation in the form of constructed wetlands under Indian climatic conditions. A pilot plant of constructed wetlands has been constructed on the premises of the Uttaranchal Jal Nigam Sewage treatment plant and municipal wastewater has been allowed to pass through the constructed wetland. It has been observed that BOD removal at 24 0C is governed by the equation Ce/Co = e-1.0042 x t and the removal rate constant of BOD has been observed to be 0.795 d-1 at 20 0C. It has been observed that the pilot-scale constructed wetland is bringing effluent BOD and TSS up to 20 mg/l and 30 mg/l respectively consistently for the duration under study. The values of hydraulic retention time, hydraulic loading, and organic loading for achieving this performance are found to be 1.75 days,13.22 cm/d, and 142.78 kg/ha. d respectively. Performance study of constructed wetland and the existing activated sludge treatment has shown that the percent removal for the parameters TSS, BOD, COD, and Fecal Coliforms is near to the same order except for TN and TP, where the activated sludge process unit shows higher removal than the constructed wetland.