하수슬러지 소각재로부터 추출된 인의 침전 분리 특성

Abstract

Incinerated sewage sludge ash (ISSA) is regarded as a valuable resource having great potential for the recycling of phosphorus. The P content of ISSA is known as around 10% as a P. Therefore, this study was undertaken to investigate the precipitation and separation characteristics of phosphorus from the acid-extracted solution of ISSA. The incinerated sewage sludge ash was leached by 1 N sulfuric acid with solid/liquid ratio of 10 for 30 min. The extracted solution contained about 1.1% of P and other metals, Al, Fe, Ca and Mg, with over than 1,000 mg/L. Some heavy metals such as Cu, Pb and Cr are presented as impurities as well. Most of Al and Fe in the extracted solution were precipitated with P when titrating it to pH 3.6. The precipitated form were assumed to AlPO4, FePO4·2H2O respectively, and Pb and Cr were precipitated in this stage as well. At this experiment, about 62.9% of the initial P was precipitated and removed from the solution. It was also find that all of the P extracted can not be recovered as a precipitate with a simple addition of NaOH, even though titrated to pH 11.6. The precipitated P also contained some impurities such as Al, Fe, and some heavy metals, which means that further researches are needed for the efficient separation and recovery of P from ISSA.