Parabond 23 is the latest arsenic removal media developed by Parabond Products International, USA. It can remove 99.5 per cent of arsenic from a solution ranging between pH 4 and 9 and works on the combined principle of adsorption as well as reduction. The filtering material is granular and comprises varying particle sizes to increase filtration. This removal medium uses particles as small as 50 microns. It can adsorb trivalent, pentavalent and organic arsenic with removal efficiencies in the part per trillion range (arsenic concentration less than 0.01 mg/l). Parabond 23, binds the arsenic tightly enough so that the spent medium can be disposed of in an ordinary landfill without fear that it may leach into groundwater. The manufacturers claim that the filtered water meets USEPA standards for arsenic in drinking water. The medium is available in two standard formulations – Parabond 23T and Parabond 23 Max. The former provides optimal arsenic binding and allows for non-hazardous disposal methods. The latter needs to be disposed of in a hazardous waste landfill.