Abstract: Biogenic silica is produced by combusting a biogenic source material such as rice hulls to give rich hull ash (RHA), and the combusted biogenic silica may be subsequently treated to improve the filtration or adsorption properties thereof e.g. by changing the surface charge, the surface tension, the surface area, the average pore size, the pore size distribution, particle size distribution, and/or the permeability thereof. Such biogenic silica is useful to remove a species, such as an impurity, from a fluid to purify the fluid and/or to recover the species therefrom. RHA may be used to remove species including organic, inorganic or microbial particulates, surfactants, metal ions, non-metallic anions, organic compounds, color bodies, odor-producing species, chlorinated compound, pigment, free fatty acids, phospholipids, peroxides, oil and/or grease different from the non-aqueous fluid, algae, bacteria, and combinations thereof.

Abstract: Biogenic silica is produced by combusting a biogenic source material such as rice hulls to give rich hull ash (RHA), and the combusted biogenic silica may be subsequently treated to improve the filtration or adsorption properties thereof e.g. by changing the surface charge, the surface tension, the surface area, the average pore size, the pore size distribution, particle size distribution, and/or the permeability thereof. Such biogenic silica is useful to remove a species, such as an impurity, from a fluid to purify the fluid and/or to recover the species therefrom. RHA may be used to remove species including organic, inorganic or microbial particulates, surfactants, metal ions, non-metallic anions, organic compounds, color bodies, odor-producing species, chlorinated compound, pigment, free fatty acids, phospholipids, peroxides, oil and/or grease different from the non-aqueous fluid, algae, bacteria, and combinations thereof.