engineering properties of substrate used in constructed wetlands treating low strength sewage under tropical conditions

Substrates play a major role to filter, adsorb, sediment, flocculate, precipitate, and exchange ions. in cw (constructed wetland), selecting substrate or bed materials is not difficult, as locally accessible, cost-effective, and environment-friendly materials can be used based on size, hydraulic conductivity, texture, porosity, etc. cw substrates undergo a multitude of purification processes, including physical filtration and sedimentation, sorption, ion exchange and microbial degradation, precipitation, and bio-immobilization in the substrate, in addition to uptake and metabolism by macrophytes. with constructed wetlands, treatment facilities with well-defined substrates, vegetation species, and flow patterns can be built with greater control than with natural systems. this report details investigations of some of the locally available substrates that all fit the requirements. based on analysis of parameters which are ph, water absorption capacity, hydraulic conductivity, porosity, surface area, bulk density, particle size distribution, d10 particle diameter, d60 uniformity coefficient, permeability and specific gravity, a comparison of four materials is presented in this paper. the study found that the construction waste materials evaluated showed satisfactory physical properties for use as filler media in constructed wetlands for wastewater treatment.