This study was performed to test the feasibility of thermophilic (55oC) co-digestion of municipal sewage sludge and food wastes. The management variables of co-digestion were the mixed ratios of municipal sewage sludge and food waste hydraulic retention times (HRTs). During the operation of thermophilic co-digestion, the reactor pH ranged from 7.0 to 7.5 and the reactor alkalinity remained above 3,200 to 4,000 mg/L as CaCO3. The volatile fatty acids concentration increased as the HRT shortened from 20 days to 10 days and the mixture ratio increased to 1:4, but did not reach toxic levels for co-digestion of sewage sludge and food wastes. Methane productivity increased gradually as the organic loading rate increased. Maximum methane productivity reached 1.03v/v-d at an HRT of 10 days and at the mixture ratio of 1:4. The TVS removal efficiency decreased from 70.6% to 58.3% as the HRT shortened from 20 days to 10 days. TVS removal efficiency ranged from 57.0% to 77% during the entire operation. It is likely that thermophilic co-digestion of sewage sludge and food wastes is a very effective method both to environmentally treat food waste and to economically produce gas for energy.

Abstract
 I. 서 론
 II. 연구방법
  1. 실험재료
  2. 실험방법
 III. 실험결과 및 고찰
  1. 통합소화 반응조(Co-Digestion Reactor) 운전
 V. 결 론
 References

• 한소영(한국기계연구원) | So-Young Han (Korea Institute of Machinery & Materials)
• 강호(충남대학교) | Ho-Kang (Chungnam National University) Corresponding author
• 최연석(한국기계연구원) | Yeon-Seok Choi (Korea Institute of Machinery & Materials)
• 김치열(충남대학교) | Chi-Yeol Kim (Chungnam National University)