Unlike fluidized bed systems, increasing diffusivity through the encapsulation matrix within the evaluated range has minimal impact on the optimal sustainability of packed bed systems, because the negative effect of low diffusivity on COD removal may be largely overcome by design decisions. Despite the higher LC and CI, packed bed reactors may be preferred over fluidized beds due to locality-specific contextual factors. If the industry is bound by a discharge permit but has limited physical space, an optimized packed bed design may make it possible for the system to consistently achieve higher COD removal than if a fluidized bed of the same size is used.