Tadaaki Kawasugi

Rite Biological Hydrogen Program

The Research Institute of Innovative Technology for the Earth (RITE) is developing hydrogen production technology based on biological processes. The objective of the project is to develop technologies for the efficient production of hydrogen, utilizing solar energy and photosynthetic microorganisms. This project, named “Development of Environmentally Friendly Technology for the Production of Hydrogen,” began in 1991 and will continue until March 1999 (total of eight years).

BIOGAS RECOVERY FROM A THERMALLY TREATED SEWAGE SLUDGE BY A FIXED-BED ANAEROBIC BIOREACTOR

Abstract Biogas recovery from the anaerobic digestion of sewage sludge which is discharged from municipal wastewater treatments generally requires a large scale digester owing to the slow biodegradability of the sludge compounds. To achieve an effective methanogenesis from the sludge as the raw materials, thermal pretreatmenls of the sludge were conducted to improve the sedimentation efficiency of the treated sludge and the filtrate obtained was anaerobically digested in fixed-bed bioreactors with baked clay, melted slug and rhyolitic lava. Methane formation from the intact activated sludge (10g/l) was 11 methane/I after 25-day fermentation without heat treatment (control), whereas in the case of treating for 1 h at 121°C, 2.1 I methane/I was produced from the whole treated sludge (10g/l) and 2.91 methane/1 was produced at pH 4 at the same heat treatment. However, no more methane was produced when the sludge was treated with 0.1 N NaOH or H2SO4 at 121°C for 1 h although lower fatty acids were accumulated....