EARTH

[31001-12-09] Transformation of phosphorus in Sewage Sludge into apatite phosphorus through the addition of calcium oxide

○Yan Jhang Chen¹, Chen Hui Liao¹, Li Pang Wang¹ (1. National Taipei University of Technology, Taipei, Taiwan, R.O.C.)

Chairman:JI Whan Ahn（KIGAM）, Richard Alorro (Curtin University)

Keywords:Phosphorus, Sewage Sludge, transformation, apatite phosphorus, recovery

Phosphorus exists in several types in sewage sludge: organic phosphorus, inorganic phosphorus, non-apatite inorganic phosphorus, and apatite phosphorus. Among these, the AP has higher bioavailability and broader industrial applications. This study investigated the feasibility and characteristics of transforming the various types of P in SS into AP through the addition of calcium oxide.
The effects of CaO dosage, reaction temperature, and reaction time were investigated. The optimal result was obtained when more than 8 wt% CaO was added at 300 Celsius degree after 2 hr. The fractions of OP and NAIP in the experimental SS sample decreased from the initial 44.2% and 32.5%, respectively, to approximately 2.5% and 9%, whereas that of AP increased from initial 23.3% to approximately 88.0%.
The main crystal phase of AP in the SS after transformation through CaO addition was calcium pyrophosphate, confirmed through Xray diffraction analysis. The results suggest that CaO addition is beneficial for the transformation of the various types of P in SS into AP under a moderate temperature.