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REDUCTION OF METAL LEACH FROM CARBON WATER FILTERS

IP.com Disclosure Number: IPCOM000173291D
Publication Date: 2008-Jul-29

Publishing Venue

The IP.com Prior Art Database

Abstract

Filtration matrixes comprising an adsorptive carbon media having a source of metal leach, a titanium oxide media, and an optional polymeric binder are provided. The titanium oxide media can be present in an amount of up to 5% by weight. The filtration matrix can remove at least a portion of the metal leach. The carbon media can be wood-based. The filtration matrix can provide a water effluent having a three-day average aluminum concentration according to NSF Standard 42 that is at least a factor of 10 less than a comparative filtration matrix comprising the adsorptive wood-based carbon media having the source of aluminum leach and the polymeric binder, the comparative filtration matrix being free of the titanium oxide media. Methods of reducing metal leach using such matrixes and making the same are also provided. The filtered effluent can comprise less than 200 ppb aluminum.

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REDUCTION OF METAL LEACH FROM CARBON WATER FILTERS

ABSTRACT

    Filtration matrixes comprising an adsorptive carbon media having a source of metal leach, a titanium oxide media, and an optional polymeric binder are provided. The titanium oxide media can be present in an amount of up to 5% by weight. The filtration matrix can remove at least a portion of the metal leach. The carbon media can be wood- based. The filtration matrix can provide a water effluent having a three-day average aluminum concentration according to NSF Standard 42 that is at least a factor of 10 less than a comparative filtration matrix comprising the adsorptive wood-based carbon media having the source of aluminum leach and the polymeric binder, the comparative filtration matrix being free of the titanium oxide media. Methods of reducing metal leach using such matrixes and making the same are also provided. The filtered effluent can comprise less than 200 ppb aluminum.

[0001] The present disclosure relates to molded composite blocks or granular activated carbon beds, and methods of making molded composite blocks and granular activated carbon beds, for example, filtration matrixes, exhibiting low levels of metal leach. More specifically, provided are filtration matrixes formed from adsorptive media, such as activated carbon, an optional polymeric binder, and a media for reducing metal leach for use in water filtration systems.
[0002] Activated carbons used to make such filters may contain trace levels of metals, such as aluminum, retained from the carbonaceous raw material or from the activation process. If water is stagnant and remains in contact with the filter media between uses of a filter, unwanted elements, such as metals, can leach from the carbon into the water. Primary drinking water standards impose limitations on metal leach amounts, and these standards can be expected to become more stringent over time.

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[0003] Primary drinking standards have been established for certain metals. For aluminum, the standard is 600 ppb, with an advisory limit of 200 ppb. For antimony, the standard is 6 ppb. For arsenic, the standard is 10 ppb, with a California Proposition 65 level of 5 ppb, and perhaps lower.
[0004] There is an on-going need to reduce metals leaching from composite blocks and granular activated carbon beds, such as filtration matrixes, into water. It is also desirable to reduce the leaching of metals such as aluminum to below the primary drinking water standards and perhaps approaching non-detect levels.
[0005] Provided are methods of reducing metal leach, filtration matrixes effective to do the same, and methods of making such filtration matrixes. In a first aspect, a filtration matrix for use in a water filtration system is provided, the filtration matrix comprising an adsorptive carbon media having a source of metal leach, a titanium oxide media, and an optional polymeric binder, the titanium oxide...