Removal of Taste, Odor, and Color

Various processes are used to remove agents that cause taste, odor, and color. Simple aeration can remove volatile materials such as odorous hydrogen sulfide. Oxidation that destroys organics usually removes taste, odor, and color as does adsorption of organics onto activated carbon. 

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In water and wastewater treatment ozone is used for the following purposes 1) disinfection 2) oxidation of organic compounds, including removal of taste, odor, and color and 3) oxidation of inorganic com-pounds.f Ozone is usually used as pre-, intermediate-, or posttreatment with other processes such as sedimentation, adsorption, filtration, etc. 

Ozone has many industrial applications. It is a sterilizing and deodorizing agent. It is used for disinfection of filtered drinking water and to purify waste-waters. It also is used in water treatment plants for removal of metal impurities by oxidizing them into insoluble compounds. This removes undesired taste, odor, and color from the water. Ozone also is used for odor control. 

Then the water is filtered again to remove the solid mass of fine particles (called a flocculate or floe ) leftover from the initial filtering treatment. Chlorine is added to kill any bacteria in the water. Then it s run through an activated charcoal filter that absorbs (collects on its surface) and removes substances responsible for taste, odor, and color. Fluoride may be added at this time to help prevent tooth decay. Finally, the purified water is collected in a holding tank, ready for your use. 

Nearly every chemical manufacturiag operation requites the use of separation processes to recover and purify the desired product. In most circumstances, the efficiency of the separation process has a significant impact on both the quality and the cost of the product (1). Liquid-phase adsorption has long been used for the removal of contaminants present at low concentrations in process streams. In most cases, the objective is to remove a specific feed component alternatively, the contaminants are not well defined, and the objective is the improvement of feed quality defined by color, taste, odor, and storage stability (2-5) (see Wastes, industrial Water, industrial watertreati nt). 

In general, the observations made in Section 4.3 as to the influence of temperature, pH, and other experimental conditions on decolori-zation apply also to the removal of taste and odor. When a situation requires the removal of both color and odor the conditions found favorable for decolorization will usually be suitable for removing... 

We judge the quality of water by taste, smell, color, and lack of pathogenic organisms or harmful contaminants. Often bad taste, odor, or color indicates contamination. Most of the water we drink has been treated to remove harmful substances and has had chlorine, ozone, or chloramines added to kill bacteria. Ordinary water contains dissolved gases such as oxygen, nitrogen, carbon dioxide, and other atmospheric components, as well as harmless minerals. 

Active carbons are unique and versatile adsorbents, and they are used extensively for the removal of undesirable odor, color, taste, and other organic and inorganic impurities from domestic and industrial waste water, solvent recovery, air purification in inhabited places, restaurants, food processing, and chemical industries in the removal of color from various syrups and pharmaceutical products in air pollution control from industrial and automobile exhausts in the purification of many chemical, pharmaceutical, and food products and in a variety of gas-phase applications. They are being increasingly used in the field of hydrometaUurgy for the recovery of gold, silver, and other metals, and as catalysts and catalyst supports. They are also well known for their applications in medicine for the removal of toxins and bacterial infections in certain ailments. Nearly 80% (-300,000 tons/yr) of the total active carbon is consumed for liquid-phase applications, and the gas-phase applications consume about 20% of the total production. 

Succinylation substantially increases specific volume of soy and leaf proteins (12,37). The succinylated soy protein becomes very fluffy and the color becomes much lighter, changing from a tan to a chalk white as the extent of derivatization is increased (12,47). No odors nor flavors were imparted by the succinylation process. Succinylation improved the whiteness and dispersibility characteristics of soy protein making it suitable for incorporation into coffee whiteners (47). Succinylated soy proteins hydrate rapidly on the tongue,""taste clean, but slightly acidic. It is not known if derivatization facilitates the removal of off-flavors from modified proteins. 

As such, it is used in water treatment to control taste and odors, remove color, and control biological growth. It promotes the removal of iron and manganese species by rendering them insoluble through oxidation ... 

Approximately 0.5% of crude coconut oil is not saponified by caustic treatment. The unsaponifiable matter consists mainly of tocopherols, sterols, squalene, color pigments, and carbohydrates. The odor and taste of coconut oil is largely due to 5- and y-lactones, which are present in trace quantities (24). Among the unsaponifi-ables, tocopherol contributes to the oxidative stability of crude coconut oil. A typical sample of crude coconut oil contained 55 ppm total tocopherols of which 40.7 ppm is cx-tocopherol (25). Most of the unsaponifiables are removed in the process of refining, bleaching, and deodorizing of crude coconut oil. 

Adsorption has been used in wastewater treatment primarily for taste and odor control, but it is growing more popular for removal of contaminants such as synthetic organic chemicals, color-forming organics, disinfection chemicals and their by-products (the most notorious being the trihalomethanes), and heavy metals. 

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