Preparation of Zeolitic Material with the Ability to Simultaneous Remove NH4+ and PO43^|^minus; from Paper Sludge using Calcination and Alkali Treatment

Abstract

Paper sludge (PS) was converted into a novel zeolitic material with the ability to simultaneously remove NH 4 + and PO 4 3-from an aqueous solution using calcination and alkali treatment. The sludge was calcined at 200-1000 °C for 6 h to have PO 4 3-removal ability, and was then converted into a zeolitic material upon reaction with a 1 -4 M NaOH solution at 80 °C to have NH 4 + removal ability. Also, the both removal abilities of the product was tried to improve using diatomite during the alkali reaction. Without the addition of diatomite, hydroxysodalite and katoite were obtained in the product, and with the addition of diatomite, zeolite-P appeared in the product. The product from the calcined PS with diatomite has a higher NH 4 + removal ability than those calcined without diatomite, and the product obtained from the 2 M NaOH solution with addition of diatomite has a high removal ability because of the zeolite-P phase in the product. On the other hand, regardless of diatomite addition or NaOH concentration the product from the PS calcined at 800 °C had a high PO 4 3-removal ability due to the present of active sites to remove PO 4 3-. The observed concentrations of Si, Al and Ca in the solutions during the reaction explain the crystallization behavior of these phases. The product synthesized from the PS calcined at 800 °C in 2 M NaOH solution with the addition of diatomite was able to simultaneously remove NH 4 + and PO 4 3-from the aqueous solution.