Synthesis and Use of Zeolite Na-A from Waste Sludge of Water Treatment Plant for Ammonium Removal

Zeolite Na-A from waste sludge of water treatment plants was synthesized via a hydrothermal process for the purpose of ammonium removal. Sludge samples, with and without burning at 700 ºC for 3 hours, were used and reacted with 3M NaOH solution. The effects of contact time, pH and initial ammonium concentration on ammonium uptake and adsorption isotherms were investigated. An optimal condition for ammonium ion adsorption was determined and then compared with Langmuir and Freundlich isotherms. Analysis of the synthesized zeolite Na-A by SEM revealed that the zeolite Na-A was cubic in shape for all experimental conditions. Zeolite was clearly observed from samples with sludge burning at the reaction time of 9 h. The cation exchange capacity of zeolite Na-A synthesized was found to be 1.07 meq/g. The adsorption capacity showed that the optimum pH and contact time were 8 and 5 min, respectively. The Langmuir model provided a better description of ammonium adsorption than the Freundlich model, and the maximum adsorption capacity by the Langmuir Isotherm was 8.88 mg/g. It was concluded that the zeolite Na-A synthesized from waste sludge has a potential to remove ammonium from wastewater.