Development of field-scale composite biorack constructed wetland – startup phase

Abstract

Constructed Wetlands (CW) with Biorack (BR) technology have been studied extensively in recent years with positive outcomes compared to conventional CWs. A field scale application of the same has been worked upon in the Composite Biorack Constructed Wetland (CBCW) which is a secondary wastewater treatment facility of the Decentralized Wastewater Treatment System (DWTS) at Walchand College of Engineering, Sangli (M.S.), India. The CBCW is a multi-compartment system comprising of compartments with brickbats as supporting medium and BR Compartments (BRC) and has been in operation since May, 2018. The CBCW is vegetated with Typha angustifolia L. and Canna indica macrophytes. Being a unique CW, studies on difficulties aroused during the startup phase need to be addressed so as to arrive at proper troubleshooting techniques for future references. The paper addresses various issues, specifically growth of vegetation and their early wiltage in CBCW, for a period of 150 days. Using alternative modes of plantation, it is concluded that vegetation acclimatization, proper suspension and grip of the bulb and roots of saplings in racks, fluctuating inflow of wastewater are few reasons influencing development of vegetation. An improvement by about 12% is obtained in COD removal in the latter period of study implying establishing of vegetation in CBCW.