Induction of hydrogen production affects micro and macro structure of granular sludge

In this work we study the potential for directing microbial anaerobic mixed communities towards improved hydrogen production. Strategies applied for promoting the selection of hydrogen-producing bacteria in anaerobic granular ludge consisted of heat treatment and chemical treatment with 2-bromo-ethane sulfonate (BES) and with S+Chloroform. Three expanded granular sludge bed reactors, RHeat, RBES and RBES+Chlo, were individually inoculated with the treated sludges. Hydrogen production was monitored and the morphological integrity of the ranules and bacterial community composition of granular sludge were assessed. This work demonstrates that different methods applied for directing granular sludge for hydrogen production can cause changes in the macro- and microstructure of granular sludge, which can be incompatible with the long-term operation of high-rate reactors