Ocean discharge of sewage sludge, which started in the year of 1993 in Korea, was stopped in the beginning of 2012, Landfill of sewage sludge was also prohibited in 2003 owing to public acceptance of the lanfill sites, and partially reopened in 2007 due to the necessity of organic component in sludge to produce methane gas. Sludge recycle ratio will increase in sewage sludge treatment by volume reduction and drying, and then recycle of the thermal energy as fuel in power plant and also material as raw material of cement. Several drying processes are compared with reasoning and an appropriate drying sequence is suggested.

• 김준형(대전대학교 환경공학과) | Joon-Hyung Kim Correspondence
• 최우진(대전대학교 환경공학과) | Woo-Jin Choi
• 임봉수(대전대학교 환경공학과) | Bong-Su Lim