Evaluation of Rural Domestic Wastewater Treatment Using a Hybrid Constructed Wetland with Three Flow Configurations

This study evaluated the performance of a hybrid constructed wetland (CW) system consisting of horizontal subsurface flow (HF), vertical subsurface flow (VF), and free water surface (FWS) units for domestic wastewater treatment under rural conditions. The system was operated at two hydraulic loading rates (HLR) of 5 and 10 cm/day to assess treatment efficiency under different operational scenarios. Results showed high removal efficiencies for organic matter and nitrogen, with average BOD₅ and NH₄⁺-N removal reaching approximately 82.6–84.8% and 85.7–88.2%, respectively. Total suspended solids (TSS) removal ranged from 67.1% to 83.8%, while total coliform removal exceeded 98%. However, phosphorus removal remained low and unstable (14.2–17.2%), indicating the need for improved substrate materials. The performance of HF units varied depending on plant species, with Caladium bicolor demonstrating superior BOD₅ removal efficiency. The integration of HF and VF units, combined with intermittent feeding, enhanced nitrification–denitrification processes and improved nitrogen removal. Overall, the study demonstrated that the hybrid CW system was an effective, low-cost, and sustainable solution for domestic wastewater treatment in rural areas without requiring recirculation.