Rheology-dependent mass diffusion characteristics of high-solids anaerobic co-digestate of food waste and sewage sludge

Mass Transfer Enhancement in High-Solids Anaerobic Digestion of Organic Fraction of Municipal Solid Wastes: A Review

“…The rheology of non-Newtonian fluids cannot be described by a single value of its viscosity (defined as the ratio between shear stress τ and shear rate γ). With the increased TS, the viscosity of high-solids digestate decreases with increasing shear rate [ 6 , 47 , 48 ]. The rheological model to characterize the rheological behaviors of different types of digestate was employed in previous studies [ 10 ].…”

“…Storage modulus (G′) and loss modulus (G″) of the digestate characterize its elastic properties and viscous properties, respectively. The presence of a higher TS content correlated with an enhanced resistance to deformation, as evidenced by elevated values of G′ and G″ [ 48 ]. A comprehensive understanding of the rheological properties involved is crucial for optimizing the performance and design of HS-AD systems.…”

“…Several studies on the rheological behavior of HS-AD focused on TS content [ 53 ], temperature [ 54 ], moisture distribution [ 48 ], and SRT [ 6 ], especially for anaerobically digested sludge ( Figure 2 a). Higher TS levels lead to an increase in flow resistance and thixotropic kinetic coefficient.…”

“…A higher temperature offers better flowability due to a higher proportion of free and interstitial water, while surface water is more prevalent in mesophilic systems. The higher surface water may lead to poor rheological properties [ 48 ]. Moreover, the rheological properties of digested sludge are significantly affected by SRT, and the SRT in HS-AD is inversely associated with the shear stress, viscosity, and yield stress [ 6 ].…”