Abstract: The invention is directed to purification of liquids, such as drinking water using filters, wherein filtration is effected while the liquid flows upwardly. The invention includes both the method and a device enabling the method to be carried out. The device is constructed to intake impure liquid at the bottom of the filter and initially to effect flow by filling liquid to above the filter outlet near the top, and maintaining flow thereafter by virtue of the presence of a low internal pressure that develops as the liquid passes through the system.

Abstract: A composite adsorbent element comprising a packed mixture of granules and fibers, which are desirably granular activated carbon (GAC) and activated carbon fiber (ACF). The element is employed as a filter for purifying tap water. In the composite adsorbent element the activated carbon fibers fill the spaces between the activated carbon granules. The size and relative amounts of the GAC and ACF are designed to enable water treatment to remove impurities from water more rapidly than conventional filters using granular activated carbon. Furthermore, when there are significant time intervals between filtration, a packed mixture of granular activated carbon and activated carbon fibers made in accordance with the invention shows an improved ability to rejuvenate its adsorption capabilities in the time intervals between filtrations.

Abstract: A composite adsorbent element comprising a packed mixture of granules and fibers, which are desirably granular activated carbon (GAC) and activated carbon fiber (ACF). The element is employed as a filter for purifying tap water. In the composite adsorbent element the activated carbon fibers fill the spaces between the activated carbon granules. The size and relative amounts of the GAC and ACF are designed to enable water treatment to remove impurities from water more rapidly than conventional filters using granular activated carbon.

Abstract: An activated carbon is modified to have bactericidal properties and/or an additional ability to remove heavy metals and other toxic substances. Said modified activated carbon is especially suitable for purifying drinking water and can be readily modified to be suitable for various regions with specific tap water impurities. Pursuant to the invention, activated carbon fiber is treated to adsorb a member of the group consisting of cations, anions, organic complex forming agents, surfactants, polyelectrolytes and organic bactericidal compounds.

Abstract: Activated carbon fiber is made by pre-treating a carbonized fibrous material, preferably a carbonized cellulose fiber, with a solution of nitrogen-containing compound, comprising at least one of the following substances: urea, ammonium carbonate, ammonium bicarbonate, ammonium acetate, and other organic salts of ammonia such as formate, carbamate, citrate and oxylate, and activating the pre-treated carbonized material at 800.degree. to 1200.degree. C. in an atmosphere comprising steam and/or carbon dioxide until a high degree of activation is produced. The activated carbon fiber material is amphoteric, wherein both acidic and basic functional groups are present on its surface. The resulting material is suitable for removing organic impurities, cations and anions from water and other fluids.