Multi-component solute transport model with cation exchange under redox environment and its application for designing the slow infiltration setup

The present trend of disposing treated sewage water by allowing it to infiltrate the soil brings a new dimension to environmental problems. It is therefore necessary to identify the chemicals likely to be present in treated sewage water. A soil column experiment was conducted to determine the behavior of chemical species in soil columns applied with secondary treated sewage water. To predict the behavior of chemical species, a multicomponent solute transport model that includes the biochemical redox process and cation exchange process was developed. The model computes changes in concentration over time caused by the processes of advection, dispersion, biochemical reactions and cation exchange reactions. The solute transport model was able to predict the behavior of different chemical species in the soil column applied with secondary treated sewage water. The model reproduced the sequential reduction reaction. To design the safe depth of plow layer where NO ₃ ^- is totally reduced, a numerical study of NO ₃ ^- leach was done and it was found out that the pore velocity and concentration of CH ₂O at the inject water was found to affect NO ₃ ^- reduction in the mobile pore water phase. It is revealed that the multicomponent solute transport model is useful to design the land treatment system for NO ₃ removal from wastewater.