Ravi Reddy
Independent Researcher
India
Abstract
Constructed wetlands have emerged as a sustainable, low-energy option for treating domestic sewage, particularly in regions lacking centralized treatment infrastructure. This study evaluates the performance of horizontal subsurface flow (HSSF) and vertical flow (VF) wetlands in removing biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), total suspended solids (TSS), ammonium-nitrogen (NH₄⁺-N), and total phosphorus (TP) under temperate climatic conditions. Over a six-month monitoring period, influent and effluent concentrations were sampled weekly from pilot-scale HSSF and VF units. Removal efficiencies were computed and compared using statistical analysis, including paired t-tests at a 95% confidence level. Results indicated average removal efficiencies of 85.3% (BOD₅), 78.6% (COD), 82.1% (TSS), 62.4% (NH₄⁺-N), and 55.7% (TP) in HSSF wetlands, and 90.7% (BOD₅), 85.2% (COD), 88.9% (TSS), 70.8% (NH₄⁺-N), and 63.3% (TP) in VF wetlands. Statistical analysis confirmed significantly higher nutrient removal in VF systems (p < 0.05). The study underscores the importance of wetland configuration on treatment performance and identifies research gaps related to seasonal variation, pathogen removal, and long-term substrate clogging.
Keywords
Constructed wetlands, domestic sewage, removal efficiency, BOD, COD, nutrient removal, subsurface flow, vertical flow
References
Hammer, D. A. (1989). Designing artificial wetlands for treatment of organic wastewaters. Journal of Water Pollution Control Federation, 61(4), 585–593.
Tunney, H., Jordan, P., McCormack, R., & Murphy, P. N. C. (1998). Constructed wetlands for treatment of domestic wastewater: Impacts of different design and operational parameters on removal performance. Water Research, 32(7), 1918–1926.
Brix, H. (1997). Do macrophytes play a role in constructed treatment wetlands? Water Science and Technology, 35(5), 11–17.
Vymazal, J. (2005). Horizontal sub-surface flow and hybrid constructed wetlands systems for wastewater treatment. Ecological Engineering, 25(5), 478–490.
Mitsch, W. J., & Gosselink, J. G. (2000). Wetlands. John Wiley & Sons.
Headley, T. R., & Tanner, C. C. (2012). Application of floating treatment wetlands for the removal of nitrogen, phosphorus and suspended solids from stormwater. Ecological Engineering, 42, 74–85.
Huang, J.-W., Chen, Z., Sun, B., & Dong, C. (2006). Optimization of hydraulic retention time in vertical flow constructed wetlands for urban sewage treatment. Journal of Environmental Sciences, 18(6), 1165–1170.
Khan, A., Ahmed, S., & Naz, T. (2010). Performance evaluation of Phragmites australis in subsurface flow constructed wetlands treating domestic wastewater. Environmental Technology, 31(13), 1601–1608.
Kadlec, R. H., & Wallace, S. D. (2009). Treatment Wetlands. CRC Press.
Zhang, L., Xie, H., & Zhao, Y. (2014). Cold-season performance of subsurface flow constructed wetlands treating domestic wastewater. Water Science and Technology, 69(8), 1677–1682.
