Liquid purification or separation – Filter – Material
Reexamination Certificate
2001-07-24
2003-06-17
Walker, W. L. (Department: 1723)
Liquid purification or separation
Filter
Material
C210S758000, C210S749000, C502S400000, C423S210000
Reexamination Certificate
active
06578715
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a product for use in controlling and treating odiferous contaminants. Specifically, the invention relates to a product for use in removing sulfur contaminants, such as hydrogen sulfide and mercaptans, while neutralizing many other common odor causing compounds in sewage gas, and a method for making and using the same.
BACKGROUND OF INVENTION
Sewer systems and similar structures, typically contain organic waste and harbor standing pools of water. It is known that bacteria thrive in conditions where adequate moisture and food (organic waste) are present. Many of these bacteria essentially convert the waste into contaminated gas. Additionally, the breakdown of the waste will also release contaminants. Hydrogen sulfide (H
2
S), mercaptans and other sulfur contaminants found in such gas, cause the gas to have a foul smell. This contaminated gas will collect due to bacteria growth in the sewer system, excessive moisture, the environment itself, and various other odor causing entities. The gas containing the odiferous contaminants will exit the sewer system causing malodors in the nearby environment.
Currently, most products for reducing or eliminating odors in a sewer system are either biofilters or are carbon-based. Biofilters use organic materials, which allow for the growth of bacteria, to reduce odors. The bacteria in these products reduce or eliminate the odors in the sewage gas. Biofilters are comparatively slow systems. The bacteria in biofilters require near 100% relative humidity in order to optimize their ability to reduce or eliminate sewage gas odors. In order to work immediately, a biofilter must be seeded with bacteria. If not seeded, the biofilter will not be able to remove hydrogen sulfide and mercaptans until bacteria grow on the biofilter. In contrast, carbon-based products require a relative humidity of near 80% or less in order to absorb hydrogen sulfide and mercaptans at a rate ranging between about 5% by weight of the carbon-based product and about 20% by weight of the carbon-based product. In conditions of high relative humidity (over 80% relative humidity), the carbon-based products absorb the water in the air. This absorption of water saturates the carbon and, therefore, inhibits absorption of hydrogen sulfide and mercaptans. Further, carbon-based products are hazardous once impregnated with the hydrogen sulfide and mercaptans.
What is desired is a product that will successfully neutralize or treat various odors found in contaminated gas, including methane, hydrogen sulfide, and ammonia. This product should preferably be capable of removing hydrogen sulfide under any of a variety of relative humidity conditions, and have increased efficiency with regards to the removal of hydrogen sulfide, while not significantly increasing the media pressure drop throughout the system. Further, the product should be able to remove the hydrogen sulfide as soon as the product is in place. The increased efficiency of the product should allow for smaller filter sizes.
SUMMARY OF INVENTION
The present invention relates to a product for treating contaminated fluids, preferably gas, and methods for making and using the same. In particular, the present invention is used for treating gases contaminated with sulfur compounds, whereby such contaminated gases emanate from a sewer or similar structure. The product is comprised of a carrier, preferably mulch, and a metal oxide, preferably an activated metal oxide. It is further preferred for such product to include an odor counteractant, a carrier for the odor counteractant, and an agent, which limits the diffusion of the odor counteractant. The product can be placed in a vessel or similar member in a position proximate to where the contaminated gas exits the system where such contaminated gas was generated. More importantly, the product should be placed in a position to filter contaminated gas.
Contaminated sewage gas typically exits a sewer through a manhole. As such, a vessel placed in the neck of a manhole may be used. As the contaminated sewage gas passes through the vessel, the product reacts with and removes sulfur contaminants from the contaminated sewage gas, while neutralizing or treating various other malodors commonly found in sewer systems.
The product removes or neutralizes the odor contaminants found in the gas by contacting such gas with reactive constituents found in the product. The metal oxide of the product will react with the sulfur contaminants in the gas so that the contaminants are substantially eliminated from the gas. The product will also release constituents, which neutralize some of the malodors found in the gas. The product includes a carrier, preferably mulch, which helps to absorb moisture. The carrier may further include non-organic matter, such as porous styrofoam for void support and nutrients.
Mulch, which usually functions as a protective ground covering that helps retain moisture in the soil, is most often made of organic matter such as wood products, compost, leaves, straw, bark, soil, clay, carbon, limestone, shale, volcanic rock, and combinations thereof. Mulch is advantageous as a carrier because it supports limited bacterial growth, absorbs some odiferous contaminants to eliminate them from the gas, and has a very porous surface, so it readily absorbs and holds moisture. A further advantage of mulch is its large surface area, which is desired because it provides an increased surface area for contacting the contaminated gas and provides more surface area for holding constituents for treating the odors. Bark mulch is most preferred because it offers a larger surface area compared to other available mulches, and is slow to degrade.
A product reactive with sulfur compounds, preferably metal oxide, is also present in the product. The metal oxide reacts with various sulfur compounds in the contaminated fluids, preferably gas, to remove hydrogen sulfide, mercaptans, and other sulfur contaminants. It is preferred if the metal oxide is activated. It is especially preferred to use an iron oxide activated with copper oxides or manganese oxides.
The third preferred constituent is an odor counteractant, which neutralizes or reduces the perceived odor levels of various malodors present in sewage gas. The odor counteractant reduces the perceived odor of malodors by possessing a virtually identical molecular configuration (size and weight) as the malodors. Malodors tend to have simple molecular forms with approximately 90% of them originating from a small group of chemicals with similar molecular structures. The odor counteractant has a virtually identical molecular configuration as the malodors and, therefore, binds to the malodor receptor sites. The odor counteractant is able to bind to malodor receptor sites in a person's olfactory system and prevent the receptor sites from receiving any malodor molecules. Thus, the binding of the odor counteractant to the malodor receptor site neutralizes the malodor and creates the perception of the area being odor free or pleasant to smell. By blocking malodors, odor counteractants eliminate the need for masking odors. The odor counteractants are placed on a carrier for the odor counteractant and combined with the carrier and metal oxide composition to form the product.
The carrier for the odor counteractant is present to limit contact between the odor counteractant and the metal oxide. The carrier for the odor counteractant does not have to be organic. This carrier can be clay, mulch, shale, carbon, porous styrofoam, porous ceramic or any other material, which is absorbent and porous. The odor counteractants are known to react with the metal oxide, thereby reducing the product life. By mixing the odor counteractant with the carrier for the odor counteractant prior to mixing with the carrier and metal oxide composition, the odor counteractant is separated from the metal oxide thereby blocking its reaction with the metal oxide, thus increasing the product life.
The odor counteractant is extremely volatile when mixed
Braga Thomas G.
Scranton Jr. Delbert C.
M-I L.L.C.
Menon K S
Thompson Colburn LLP
Walker W. L.
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