Hydrogen permeability of the hollow fibers used in H ₂-based membrane biofilm reactors

We developed and used steady-state permeation tests and a mathematical model to determine the H ₂ permeabilities of three hollow fibers (composite, polyester, and polypropylene) commonly used in the H ₂-based membrane biofilm reactor (MBfR). The H ₂ permeabilities spanned a wide range: 1.6×10 ^-6, 1.8×10 ^-7, and 6.6×10 ^-8 m ³ H ₂ @ standard temperature and pressurem membrane thickness/m ² hollow fiber surface areadbar for the composite, polypropylene, and polyester hollow fibers, respectively; this represents a ratio of the maximum H ₂ flux for composite:polypropylene:polyester hollow fibers=32:3.3:1. The H ₂ permeabilities were then used to correlate hollow-fiber type to contaminant-removal flux in previous MBfR experiments. Only the experiments with composite hollow fibers were not routinely limited by H ₂ delivery, although fouling by mineral precipitates lowered the H ₂ flux in some cases. Since existing contaminant-removal data for the polyester hollow fibers were not adequate, we did special experiments to investigate the effect of H ₂ pressure on contaminant removal in the MBfR with the polyester hollow fibers. We confirmed that this hollow fiber was operated at its maximum H ₂-delivery capacity based on its H ₂ permeability.