Colloid-facilitated transport of ammonia-nitrogen in water-bearing media

The effects of kaolin colloids on the transport of ammonia-nitrogen in water-bearing media were studied by sand packed laboratory columns under four different concentrations of colloid. The results showed that the breakthrough curves experienced three stages: "not-yet-breakthrough", "breakthrough in process" and "stable-breakthrough". The pore volumes corresponding to relative concentration of 0.50 are 2.68, 2.41 and 1.83 for kaolin colloidal concentrations of 15, 25 and 60 mg/L, and to be reduced pore volumes of 1.02, 1.29 and 1.87 respectively than that of in the absence of colloid. For kaolin colloidal concentrations of 15, 25 and 60 mg/L, the colloid facilitation efficiency factor (CFEF) are 0.28, 0.35 and 0.51, and the ratio of ammonia nitrogen of retention in the column to total ammonia of influent is 20.33%, 18.45% and 14.72% respectively, lower than that in the absence of colloid.