Sustainable Biofilter Technologies for Domestic Effluent Treatment: Experimental Investigation and Process Modelling

The discharge of municipal wastewater has become an environmental issue for the region at large, particularly in rapidly urbanising areas where the treatment facilities are not sufficient. Nature-based methods such as wetlands are a sustainable treatment process as they are low energy consumption, less operation time, and have environmental benefits. This study investigated horizontal subsurface flow constructed wetlands with different vegetation and filter media combinations to remove nutrients and heavy metals from municipal wastewater. Three wetland systems were investigated with sand, gravel, biochar, and selected macrophytes: Phragmites australis and Typha latifolia. The treatment performance was measured by measuring the concentrations of total nitrogen, ammoniacal nitrogen, total phosphorus, cadmium, lead, zinc, and copper before and after the treatment. The presence of vegetation was found to significantly improve the removal of pollutants from the wetland compared to the unplanted control. The wetland with biochar and Typha latifolia received a very good treatment and removed more than 80% of nutrients and about 85 to 89% of heavy metals. The media adsorption, microbial change, root zone oxygen transfer, and phytoremediation all resulted in enhanced treatment efficiency. The findings indicate that the constructed wetlands can act as an efficient decentralized wastewater treatment system and contribute to sustainable water resource management. The presence of plants in the wetland should also be considered beneficial for the plant species and the media structure for fertilization and the effective removal of nutrients and heavy metals.