While there are several forms of arsenic, in water there are only two. As3 (arsenite) which is neutral and As5 (arsenate) which has an anionic charge. Being neutral, the As3 is the hardest to remove from water with most technologies unless it is converted to As5 first. Many private and public water supplies that contain arsenic find that it is present in the As5 form directly from the well. When analyzing a water supply, the water should be tested for both in order to have the correct and least expensive system installed.

Conversion of the As3 to As5 can be done by adding some form of oxidant to water prior to the water passing through the treatment equipment. Chemicals that may be used include chlorine, bromine, iodine, potassium, permanganate and ozone. The problem with such chemicals, most have to be removed before they reach the treatment system. This adds to the cost of operation and requires additional maintenance.

There are several companies promoting arsenic reduction products to the public and while most of these products reduce arsenic, Krudico has found that two tested technologies are clearly the most reliable and cost effective. These two technologies may be used by home owners as either Point of Use or Point of Entry installations. For public water systems, again either will work extremely well with the choice dependent on the water chemistry of the water to be treated.

Krudico, Inc., in conjunction with the New Jersey Geological Survey (who did all of the testing), spent three years in compiling data on various medias and methods used to reduce/remove arsenic from water. - Many thanks from the water treatment industry to Steve Spyad of the NJGS for his time and efforts to determine fact from fiction regarding the technologies being promoted.

Technologies Meeting the Test

For POU installations, the most cost effective means of arsenic removal is to install an undercounter iron oxide absorption media cartridge unit. The adsorption media cartridge unit. The adsorption media removes both As3 and As5 without the need for oxidation. As of this time, the NJGS has surpassed 100,000 bed volume throughputs of arsenic water containing 40 -62 ppb of arsenic. No other adsorption or filtration media has come close to this figure. This adsorption media has a secondary advantage, once the cartridge or media is filled to capacity, it may be discarded in the local landfill as the arsenic will not be released from the media to recontaminate future ground water supplies. The system is economical and easy to install. Everything needed for the installation is included, including a tee to hook the water up to the ice maker in the refrigerator.

Krudico's POU arsenic reduction system

The As - Ad - 10 Arsenic Reduction under counter unit pictured to the right will reduce the arsenic in water to undetectable levels <0.2 ppb, in 1,000 gallons of water. Both As3 and As5 are removed. System shipped complete with a LED monitor located in the base of the faucet that shines green for the first 90% life of the cartridge, yellow from 90% - 100% and red thereafter. This is the indicator that when the monitor changes from green to yellow, it is time to order a new replacement cartridge. Not shown is Krudico's As - Ad - 20 model which is 20" long and holds twice the media. This model will treat 2,000 gallons of water before cartridge replacement is needed.

For Point of Entry (POE), if the water supply contains all or some arsenic in the As3 form, the same media as in our POU model should be used unless pre-treatment is applied to oxidize the As3 As5. These units are depth filters containing varying amounts of the As-Ad media, depending on the flow rate requirements and the water usage. Differing sizes are available to accommodate flow rate needs.

For the averaged sized home with a family of 3 -6 persons, our As-Ad 12-52 is the proper choice. This will handle an average flow rate of 6gpm and treat 1,000,000 gallons of water containing from 10 - 60 ppb of arsenic in either form, As3 or As5. The life of the media will be around 3 - 4 years before replacement is needed. Again, this system comes complete with a meter to calculate gallons used and has a LED light to give a warning when the media should be replaced.

For other situations, please contact Krudico and we will size equipment according to your needs. We need to have a full water analysis, water line size, gpm required, average/peak/daily water use, and what the water is being used for.

Once the media has been replaced, the old media may be disposed of in any landfill, as it will not contaminate future ground water supplies.

With the anion resin, we exchange the arsenic for the chloride side of salt. When regenrated with salt (sodium chloride), the arsenic is released from the resin beads and replaced with chlorides. During the service cycle, the chlorides are release as the arsenic is exchanges onto the anion resin beads.

Water flow rates are up to 5gpm per cu. ft.

Krudico also has large industrial or municipal systems available with flow rates of 20-1,000 gpm. For large commercial, industrial or municipalities, we need to know the daily water usage average, peak daily usage, gallons per minute being pumped through the treatment facility, water line size along with a complete water analysis.

Other technologies that have been tested to remove arsenic include Reverse Osmosis and greensand filters.

Reverse Osmosis did a respectable reduction on arsenic in the As5 form but proved to have a minimal effect on As3.

On large scale pilot test, the greensand had minimal effect on both the As3 and the As5.

On one major pilot test, and economical installation was made using flocculation and filtration.

Krudico has pilot study grafts available on all of the technologies discussed. Please contact us for these papers if additional information is desired.