RIO TINTO ALCAN

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Water Treatment

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Potable Water Applications

Alcan Water Treatment Products are adsorbents which remove contaminants by a combination of chemisorption and physisorption and particulate (or physical) filtration for the removal of metal contaminants from water. Activated alumina, with its many types of adsorptive sites and high surface area, is the perfect choice for the adsorption of various unwanted minerals in water, with proven results for arsenic, high levels of fluoride, copper, zinc, lead and phosphates. There is also the potential for chromium, silica , selenium and mercury.

Arsenic

In areas with high natural concentrations, arsenic causes arsenic poisoning, as well as having been identified as a contributing factor for different forms of cancer. The identification of this problem has precipitated the lowering of MCL levels in much of the world from 50 ppb (parts per billion) to 5 ppb or less. Used with regeneration, activated alumina was the accepted best technology when compliance levels were less demanding. New requirements needed to be developed for higher uptake capacity and the ability to remove arsenic cost-effectively without regeneration or creating hazardous waste requiring special handling.

Alcan's attention was drawn to the situation in India and Bangladesh. Rural areas had very high levels of arsenic in their water, yet lacked the means to build large public water systems with regeneration. Alcan designed an iron enhanced activated alumina, ActiGuard AAFS50, to increase the arsenic adsorption capacity while maintaining all of the physical properties necessary to work effectively in a wide range of conditions. ActiGuard AAFS50, a globally patented iron-enhanced activated alumina, is a highly effective low-cost adsorptive material. It has been identified by the Arizona Department of Environmental Quality as the most cost-effective technology for arsenic removal. Currently, it's being used globally for spring water bottling, point of use and point of entry, as well as small public and municipal systems. It is also being used in simple, small, gravity-feed domestic units in Asia where the requirements are 7-10 liters per day per individual.

Fluoride

Fluoride is generally felt to be beneficial for dental health at levels up to 1.5 ppm (parts per million). However, at higher levels it has been linked to fluorosis, causing debilitating bone structure disease, as well as discoloration and mottling of teeth. Fluoride at harmful levels occurs naturally in many of the same regions as arsenic in ground water.

Alcan provides Fluorograde AA400G, an activated alumina product, for fluoride removal. Due to the higher levels of fluoride as compared to arsenic, regeneration is usually required to make it cost-effective. Promoted products can be provided for applications where regeneration isn't feasible.

AVAILABLE EQUIPMENT OPTIONS

ActiGuard Arsenic and Fluoride Removal Systems

ActiGuard systems can be designed for water systems as small as 25 gpm to beyond 3000 gpm. Systems are based around a simple adsorptive model using a lead lag design incorporating 5 minutes of empty bed contact time. The highest grades of materials are used. FRP, epoxy-coated steel, and stainless steel columns are available.

It can be supplied as a turnkey operation, along with training for operators, modular units, lease, purchase, lease to own, or contract for water treatment at cost per 1000 gallons.

Modifications available:

- Regenerative systems with caustic and acid feed.
- pH adjusting systems with either acid or CO2 feed.
- Manual or automatic backwashing available.
- All of the above can be provided, allowing you to realize the most cost-effective system per 1000 gallons of water treated.

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Arsenic Removal

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For 25 years, activated alumina has been the preferred media for arsenic removal from water. As an industry leader Alcan Specialty Aluminas has developed a new, improved grade ActiGuard AAFS50 with up to three times the capacity of standard activated alumina.

By taking an already successful media and using a patented, proprietary process, Alcan ActiGuard AAFS50 the easiest and proven most cost effective media available.  Tests on systems in the field have yielded results in which arsenic levels of over 1,200 ppb have been reduced to less than 5 ppb.

Historically, regeneration was the accepted method of making activated alumina systems cost- effective. Regeneration however, has some drawbacks, including the handling and storage of chemicals, additional processing steps, and the disposal of regeneration effluent.  Regeneration is not realistically feasible for POU and POE systems.  The greater adsorptive capacity of ActiGuard AAFS50 makes it economical for one-time use and disposal.  Spent material has met the TCLP and California WET Test standards and may be placed in a landfill. The material is a very robust granule and will not break down or deteriorate with use as iron based media. The low pressure drop provides a system requiring less maintenance.  Pre-filtered water will allow the adsorptive system to operate virtually without back washing.  It is effective on both As(III) and As(V), note the capacity for As(III) is sixty five percent of that for As(V) and therefore oxidation is recommended.

Low media cost, coupled with the simple flow through design (EBCT of 5 minutes or less) makes Actiguard AAFS50 the preferred media for arsenic removal in most situations.

Large municipal systems will have to weigh the advantages provided by ActiGuard AAFS50 with the operating cost and economies provided by a regenerated AA400G activated alumina system.

Alcan products are being used in municipal, bottled water, POE, POU units globally. The performance of activated alumina and ActiGuard AAFS50 in any application will depend on the water treated.  The data provided herein is for guideline purposes only.  Users are advised to check the performance of Alcan Products prior to their adoption into any system.

ActiGuard AAFS50 is activated alumina promoted with a proprietary additive. This combination has been engineered for enhanced arsenic removal from water. AAFS50 has shown arsenic capacities of two to three times greater than unpromoted activated alumina.

Arsenic commonly occurs in two forms: As(V) (arsenate) and As(III) (arsenite). Maximum arsenic capacity is achieved when dealing with As(V).

AAFS50's capacity for As(III) adsorption is about 40% its capacity for As(V). Oxidation is recommended to assist with As(III) removal, when possible. Simple chlorination will oxidize As(III) to As(V) allowing complete removal.

ActiGuard AAFS50 can be effective at a wide range of pH levels depending on the competing ions present. Where high levels of silica are present, along with a pH level higher than 7.0, an adjustment may be necessary for optimum results.
The performance of any adsorbent is dependent on the water being treated. The data provided is for guideline purposes only. Users are advised to check performance prior to their adoption into a system.

Available in granular form in sizes 28 x 48 mesh, with other sizes being supplied on special request.

Packaged in 907 kg (2,000 lb.) super bags, 158 kg (350 lb.), 45 kg (100 lb.), and 22 kg (50 lb.) boxes. Other forms of packaging can be considered on special request.

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Water Treament Contd...

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Water Remediation Applications

Storm Water Runoff: Even rainwater can be environmentally damaging when it contains soluble metals which have leached into the environment from industrial sites, scrap yards, and the like.

To keep local water resources clean and safe, AAFS50 is currently being used to treat storm water runoff at a number of locations for a variety of different contaminants. These include copper and zinc removal from runoff at metal recycling centers, and phosphate removal for the protection of lakes. Normally, the first quarter inch per rainfall event is treated.

Remediation: Improper disposal of contaminants in past decades, along with newly identified issues, are creating new remediation sites on a regular basis. AAFS50 is proving to be the most cost-effective route for many of these applications. It's currently being used at EPA Superfund sites for arsenic remediation. One site utilized AAFS50 to lower extremely high levels of arsenic (17 parts per million) to compliance levels. Another site has been treating 110 gpm with 50-60 ppb of arsenic continuously for two years without media replacement.

Ballast Water: Sacrificial zinc anodes used in the ballast tanks of large ships to reduce corrosion do their job well. Unfortunately, they also create a discharge with high zinc levels. AAFS50 has proven to be a cost-effective method for reducing the zinc to acceptable levels in harbors and shipyards.

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Products


ActiGuard AAFS50

The ActiGuard AAFS50 Activated Alumina is specifically designed to remove arsenic from potable water.

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