We investigated the effects of leaching concentration (0.1 ~ 1.0 M) and time (1 ~ 120 min) on the phosphorus recovery from ash and dried sewage sludge produced by titanium tetrachloride (TiCl4) flocculation by acidic (H2SO4 and HCl) or alkaline (KOH and NaOH) leaching. The extraction efficiencies of dried sludge were 2.7 ~ 12.6% for H2SO4, 2.5 ~ 10.5% for HCl, 3.6 ~ 9.6% for KOH, and 7.1 ~ 9.9% for NaOH with 1 M, and the maximum efficiency was obtained within 45 min. The maximum %P extracted of sludge ash was 83.1 for H2SO4, 80.2 for HCl, 51.2 for KOH, and 51.2 for NaOH with 1 M, obtained within 45 min. The rate constants (min−1) for the leaching of P from sludge ash were found to be 1.199 for H2SO4, 1.026 for HCl, 0.264 for KOH, and 0.622 for NaOH. The P leaching increased with the increase in leaching concentration, and the maximum leaching for ash was obtained within 0.3 M, regardless of acidic or alkaline leaching. The overall results indicate that the ash of TiCl4 flocculated sewage sludge can be treated with H2SO4 to efficiently recover P.

Abstract
 I. 서 론
 II. 연구방법
  1. 실험방법
  2. 분석방법
 III. 결과 및 고찰
  1. 건조 슬러지와 슬러지 회분 성상
  2. 건조 슬러지
  3. 슬러지 회분
 IV. 결 론
 References

• 이기봉(강원대학교 환경공학과) | Gi-Bong Lee (Department of Environmental Engineering, Kangwon National University)
• 심동섭(강원대학교 환경공학과) | Dong-Seop Shim (Department of Environmental Engineering, Kangwon National University)
• 심혜수(강원대학교 환경공학과) | Hye-Su Sim (Department of Environmental Engineering, Kangwon National University)
• 조민희(강원대학교 환경공학과) | Min-Hui Jo (Department of Environmental Engineering, Kangwon National University)
• 안종화(강원대학교 환경공학과) | Johng-Hwa Ahn (Department of Environmental Engineering, Kangwon National University) Corresponding author