Treatment of Wastewater using Hybrid Constructed Wetlands

Abstract

Hybrid Constructed Wetlands (HCWs) are advanced, nature-based wastewater treatment systems that combine different wetland types—most commonly horizontal subsurface flow (HSSF) and vertical flow (VF) units—into a single treatment chain. This integrated design leverages the unique strengths of each system while mitigating their individual limitations. The HSSF unit supports stable anaerobic conditions for organic matter degradation, whereas the VF unit facilitates oxygen transfer and nitrification through intermittent vertical percolation. Further, they deliver robust treatment performance with minimal reliance on external energy. The value of HCWs lies in their sustainability, cost-effectiveness, and low operational requirements, making them especially relevant for regions where centralized treatment infrastructure is limited. Their scalability allows deployment across households, institutions, and small communities. The present study investigates a pilot HCW at the VBIT campus, constructed with gravel, sand, soil, and impermeable liners, and planted with resilient species such as Typha and Phragmites. The system’s effectiveness is assessed against key water quality parameters including biochemical oxygen demand (BOD), dissolved oxygen (DO), suspended solids, dissolved solids, nutrients, pH, and temperature. Expected outcomes include significant reductions in pollutants and compliance with regulatory standards. Beyond treatment, the project showcases HCWs’ role in promoting biodiversity, educational engagement, and campus sustainability objectives.