All indicators of packed bed systems were sensitive to the uncertainty in bed voidage (𝐷 ∈ [0.13, 0.16], 𝑝 < 0.01). Comparison of the distributions of packed bed voidage between the top 25% and the bottom 75% samples (Figure ) suggested the anticipated benefit of better COD removal from lower voidage is unlikely to overcome the additional costs and impacts associated with more encapsulant materials required to make up a certain working bed volume. Therefore, it is recommended technology developers target loose and homogenous packing throughout longterm operations of a packed bed system. Direction of the water flow and production of biogas may introduce more uncertainty to the bed voidage during operation and thus should be taken into consideration in system design. The uncertainty in substrate diffusivity through the encapsulation matrix (i.e., the bead-to-water diffusivity ratio) also had a significant impact on all packed bed indicators (𝐷 ∈ [0.10, 0.14], 𝑝 < 0.05). CI of fluidized bed systems and rCOD of packed bed systems were also found mildly sensitive to the biomass encapsulation capacity (i.e., maximum encapsulation density). Given the importance of encapsulant materials to LC and CI, future research and development should prioritize the continued development of these materials as well as the characterization of correlations or interactions among different material properties to reduce the prediction uncertainty of system performance and facilitate sustainable design of the encapsulation matrix.