Enhancement of water reuse by treating wastewater in constructed wetlands: Minimization of nutrients and fecal coliform

Abstract

“CW4Reuse” i.e., Constructed Wetland for Reuse technology, the eco-centric, low-cost approach for the management of domestic wastewaters has been developed at IIT Bombay, Mumbai. The Town of Mhaswad in the State of Maharashtra, India (population 25,000) has been perpetually facing drought to the extent that the livestock suffers death or migration during the summer months. In this study, the performance of the wastewater treatment plant based on ‘CW4Reuse’ technology has been investigated. Raw untreated wastewater polluted the Manganga River till the constructed wetland was commissioned. The treatment plant consists of nine horizontal subsurface flow constructed wetland beds each having dimension of 18 m × 4 m and 0.6 m depth. The constructed wetland beds are vegetated with Canna indica species. The present study investgates the system’s performance with respect to BOD5, COD, TP, TKN as well as fecal coliform. The operating conditions and routines shall be mapped with the corresponding efficiencies of removal of TP, TKN, and fecal coliform with the aim to maximize the removal of nutrients and pathogenicity. Currently, the treatment system is removing 74% COD and 92% of BOD5, while the treatment plant is subject to around 250 mg/L of COD and 100 mg/L BOD5. It is recognized that the community would like to put the treated water for high-end reuse applications including toilet flushing, floor washing, and other body contact applications for vegetables and cash-crop cultivation. Kinetic studies are being conducted in the existing treatment systems by varying different operating conditions to achieve improved performance.