Abstract: A filter medium capable of removing microorganisms from a fluid such as water. The filter medium includes particles of activated carbon, particles of a substantially insoluble inorganic material having an isoelectric point greater than the fluid being filtered. A low melt index binder, preferably with a melt index of less than about 1 gram per 10 minutes, binds the particles of activated carbon and particles of inorganic material, such that the binder will become tacky at elevated temperatures without becoming sufficiently liquid to substantially wet the particles of activated carbon and inorganic material. An antimicrobial material can be incorporated into the filter to prevent biofilm growth. The use of a biocidal material in combination with the high isoelectric point material provides a trap-and-kill mechanism for microorganism removal.

Abstract: Water treatment devices that include filtration media with specified grain size distributions are provided. In one arrangement, the device contains a volume of grains such that between about 1 and 15 vol % of the grains have a grain size in a range between a first grain size and a second grain size, a first portion of the grains have grain sizes smaller than the first grain size, and a second portion of the grains have grain sizes larger than the second grain size. The first grain size can be between about 50 and 100 ?m and the second grain size can be between about 100 and 150 ?m. In other arrangements, the first grain size can be between about 70 and 90 ?m and the second grain size can be between about 100 and 130 ?m. The difference between the first grain size and the second grain size can be at least 20 ?m. In other arrangements, the difference between the first grain size and the second grain size can be at least 10 ?m.