A comparative study of granular activated carbon and sand as water filtration media with estimation of model parameters

The use of Granular Activated Carbon (GAC) and naturally occurring silica (Sand) as filtration media in water and waste water treatment systems is very common. While GAC offers the additional functionality of being an \"intermittent\" manner over extended time, to \"simulate\" performance over the life of the filter bed. The experiments were continued till a significant drop in water flow rate through the bed was observed. A novel \"deposition\" and \"detachment\" rate based transient mathematical model is developed. It is observed that the data from the experiments can be explained by the above model, for different aqueous phase electrolyte concentrations. The model \"parameters\", namely the \"deposition\" and \"detachment\" rates are evaluated for the 2 filter media studied. The model suggests that the significantly better performance of GAC in colloid filtration is probably due to significantly lower detachment of colloids from the same. While the \"deposition\" rates are higher for GAC, the \"detachment\" rates are significantly lower, which makes GAC more effective than sand for colloid removal by over an order of magnitude.