Ammonium Removal using Batch and Fixed Bed Column by Zeolite A-carbon Synthesized from Coal Bottom Ash

Abstract

Bottom ash is coal ash waste released due to the usage of coal in the electric power plant. According to data reported by Ministry of Environment Indonesia, bottom ash waste was about 58 ton/day (Said, 2010). The coal ash waste is clasified as hazardous and dangerous waste under Indonesian regulation (PP85/1999), because it could cause self burning and negative impact to human health. Therefore, the ash waste must be utilised such as by converting the ash to become zeolite-carbon. On the other hand, ammonium is one of the significant contaminant of wastewater. The excessive presence of ammonium could cause eutrophication of stuaries, rivers, lakes and coastal seas, corrosion or biological fouling problem in industrial water system (Widiastuti et al, 2011). Zeolite is a potensial material to remove ammonium from wastewater. The zeolite framework generates one negative charge on the framework owing to the substitution of aluminum (Al3+) atom for silicon (Si4+) in the three dimensional framework of aluminosilicate tetrahedral (Englert and Rubio, 2005). The negative charge in the zeolite framework is balanced by cations such Na+, that can be exchanged by the ammonium ion. Zeolite A is a type of zeolite that has Si/Al ratio of 1 resulting in high ion exchange. This research focuses on the effectiveness of ammonium removal using batch and fixed bed column by zeolite A-carbon synthesized from coal bottom ash. The zeolite A-carbon was synthesized by fusion method in nitrogen atmosphere followed by a hydrothermal treatment (Yanti, 2009). Adsorption capacity of the synthesized zeolite was determined in batch by varying contact time (Figure 1), initialconcentration of ammonium and pH. The theoritical aspect of adsorption including adsorption isotherm and kinetics were also studied (Table 1).