Design and development of novel composite media for domestic wastewater treatment in constructed wetland

The study focuses on the design, development, optimization, and performance of novel porous composite media prepared using bulk utilization of Fly Ash (FA), Waste Tyre Rubber (WTR), Rice Husk Ash (RHA), and a minute amount of Cement (C) blended with water to eliminate the need for chemical additives. Various compositions were prepared and evaluated based on engineering properties, resulting in three optimized mixes: 80%FA + 20%C, 50%FA + 30%WTR + 20%C, and 50%FA + 15%WTR + 15%RHA + 20%C on weight basis. Morphological and physicochemical characterization was carried out using FESEM, EDX, and BET analyses. The optimized media were evaluated in a laboratory-scale wastewater treatment system consisting of an upflow anaerobic baffled reactor (UABR) followed by a baffled constructed wetland (CW), considering without and with wetland plants for six months at 24h HRT. The UABR unit achieved high removal efficiencies for suspended solids and moderates toward organic matter. Further CW with composite media improve the treatment performance mainly due to combined physical filtration, adsorption, microbial degradation, and plant-assisted nutrient uptake mechanisms. CW with developed media and wetland plants performed much better than conventional media with plants. TCLP analysis confirmed environmental safety, demonstrating the developed media as a sustainable and cost-effective alternative for treatment in a constructed wetland.