A method for removing at least one contaminant from a fluid stream by filtering the fluid stream with a filtration medium. The filtration medium includes an impregnate. The impregnate includes a surfactant such as sulfamic acid. The medium has from about 0.1 to about 25% by weight of impregnate. The method is useful for removing one or more volatile organic compounds, particularly formaldehyde, from the fluid stream. In some embodiments, the method includes removing at least two volatile organic compound contaminants from the fluid stream.