Granulation during the start-up of a UASB reactor used in the treatment of low strength wastewaters

A glucose-based wastewater was efficiently degradaded by acidogenic bacteria, with a glucose removal efficiency close to 90%, and although a distinctive granular structure could not be observed, fluffy conglomerates developed in an Upflow Anaerobic Sludge Blanket (UASB) reactor. Subsequently, the pre-acidification of the wastewater promoted the granulation process. An enrichment in methanogenic bacteria was observed on the microscope and was confirmed by an increase in the specific methanogenic activity from 0.1 up to 0.5kgCOD/kgVSS.day. Such dynamics of microbial communities was also verified through changes in the polysaccharide and protein content, as well as in the electrophoretic mobility of the biomass.