Rheological properties help the monitoring of anaerobic digestion and co-digestion processes

The rheology of different sludges from anaerobic digestion and co-digestion processes is studied. Rheological properties show two main exponential rel ations with TVS. One refers to the anaerobic digestion of sewage sludge and a mix of these with Venice Lagoon algae, and the other to the digestion of organic fraction of municipal solid waste, source sorted and mechanically sorted. The model Validity increases adding the capillary suction time as t he control parameter, but only in the case of single substrate feed. Howeve r, digestion yields parameters and operative conditions help the evaluation of the rigidity coefficient and yield stress. Following this approach, spe cific gas production represents the typical parameter of substrate characte ristics, hydraulic retention time is an index of the feed transformation, t otal volatile solids and total fixed solids substitute the number of intera ctions between particles.