Hydrogen production and microbial diversity in sewage sludge fermentation preceded by heat and alkaline treatment

Combined pretreatment of heat treatment with alkaline condition was applied to the sewage sludge in order to acquire the effective method for sludge solubilization and bio-hydrogen production. Solubilization ratio of the sludge with heat treatment at alkaline condition (pH 13) was as high as 85.0%, resulting in an increase of COD concentration in aqueous solution, but the ratio of sludge with heat treatment or alkaline treatment alone was 32.2% and 56.3%, respectively. During the fermentation of the pretreated sludge, a significant increase of hydrogen production was observed with a low strength of ammonia, showing that ammonia in the aqueous phase could inhibit bio-hydrogen production. Klebsiella, Enterobacter or Clostridium genus were mostly related on the hydrogen production.