A simultaneous removal of ammonium and turbidity via an adsorptive coagulation for drinking water treatment process

The utilization of natural zeolite (NZ) as an adsorbent for NH₄⁺ removal was investigated. Three types of NZ (i.e., NZ01, NZ02, and NZ03) were characterized, and their NH₄⁺ adsorption process in aqueous solution was evaluated. The effect of pH towards NH₄⁺ adsorption showed that the NZ01 has the highest NH₄⁺ adsorption capacity compared with other natural zeolites used. The application of NZ01 for a simultaneous removal of NH₄⁺ and turbidity in synthetic NH₄⁺-kaolin suspension by adsorptive coagulation process for treating drinking water was studied. The addition of NZ01 into the system increased the NH₄⁺ removal efficiency (η_NH4+) from 11.64% without NZ01 to 41.86% with the addition of 0.2 g L^-1 of NZ01. The turbidity removal (η_T), however, was insignificantly affected since the η_T was already higher than 98.0% over all studied parameter's ranges. The thermodynamic and kinetic data analyses suggested that the removal of NH4⁺ obeyed the Temkin isotherm model and pseudo-second-order kinetic model, respectively. Generally, the turbidity removal was due to the flocculation of destabilized solid particles by alum in the suspension system. The η_NH4+ in surface water was 29.31%, which is lower compared with the removal in the synthetic NH₄⁺-kaolin suspension, but a high η_T (98.65%) was observed. It was found that the addition of the NZ01 could enhance the removal of NH₄⁺ as well as other pollutants in the surface water.