Abstract: The present invention relates to porous substrate compositions and methods for producing such compositions. In one embodiment, the porous substrate composition of the present invention comprises sintered spherical particles of a substantially uniform size. The porous media compositions of the present invention comprise relatively randomly-ordered particles with a void fraction significantly higher than compositions with a more ordered, close-packed configuration. The present invention further relates to composite porous media compositions comprising two or more relatively discrete layers of sintered particles.