Assessment of the Effectiveness of Constructed Wetlands for Domestic Wastewater Treatment in Enugu State

This study assesses the treatment effectiveness of surface-flow constructed wetlands for domestic wastewater management in a peri-urban community in Enugu State, South East Nigeria. Constructed wetlands represent a low-energy, low-maintenance treatment technology suitable for communities lacking access to centralised sewerage, and they are increasingly promoted as an appropriate technology for Nigerian communities where conventional treatment infrastructure is unaffordable. A pilot-scale surface-flow constructed wetland planted with Typha australis was evaluated over twelve months at a site in Agbani Local Government Area receiving domestic grey water and black water from a community of approximately 500 residents. Influent and effluent sampling was conducted monthly, with parameters including biological oxygen demand, chemical oxygen demand, total suspended solids, ammonia nitrogen, total phosphorus, and faecal coliform measured. Results show that the constructed wetland achieves an average biological oxygen demand removal of 84 percent and faecal coliform reduction of 99.2 percent during the wet season. Performance is reduced during the dry season harmattan period due to lower evapotranspiration and reduced plant activity, with biological oxygen demand removal declining to 71 percent. Ammonia removal averages 62 percent across all seasons, indicating a limitation of the surface-flow configuration for nitrogen removal. Effluent quality during wet season conditions meets the Federal Ministry of Environment effluent discharge standards. The study recommends constructed wetland technology for community-scale wastewater management in South East Nigeria with provision for enhanced nitrogen removal in future design iterations. Keywords: constructed wetland, wastewater treatment, domestic sewage, nutrient removal, Enugu State.