Influence of hydrodynamic shear forces on properties of granular biomass in a sequencing batch biofilter reactor

The paper reports the results of an experimental investigation aimed at evaluating the role of hydrodynamic conditions on properties (physical, chemical and biochemical) of granular biomass grown under aerobic conditions in a SBBR (i.e. sequencing batch biofilter reactor). The granular biomass was characterised by a high density (i.e. 70–110 g VSS/Lbiomass) that permitted to achieve a biomass concentration such high as 20–38 g VSS/Lbed. The biomass density increased quasi-linearly with the increase of shear forces. The extracellular polymeric substances (EPS) content was rather low (5–6% of the total organic matter) and mostly made up of proteins whereas the cellular protein content, a parameter frequently used as an indicator of microorganisms activity, was high (30–60% of total organic matter).In addition, the EPS content and composition were not affected by hydrodynamic shear forces as well as the biomass hydrophobicity and protein content that, however, both seem to be affected by starvation.