Technologies and Costs for Removal of Arsenic From Drinking Water

# Minimally skilled labor - $14.50 per hour (population less than 3,300 individuals).# Skilled labor - $28.00 per hour (population greater than 3,300 individuals).# Life of unit - 5 years (POU), 10 years (POE).# Duration of cost study - 10 years (therefore, two POU devices per household).# Cost of water meter and automatic shut-off valve included.# No shipping and handling costs required.# Volume discount schedule - retail for single unit, 10 percent discount for 10 or moreunits, vendor retains 30 percent profit on more than 100 units.# Installation time - 1 hour unskilled labor (POU), 3 hours, skilled labor (POE).# O&M costs include maintenance, replacement of pre-filters and resin cartridges,laboratory sampling and analysis, and administrative costs.Arsenic removal by AA is very sensitive to pH, and finished water pH typically will be higherthan the optimal required for AA. A finished water pH for many systems would be in the range of pH7 to pH 8. Using data on activated alumina run length and pH, it was determined that viable runlengths for POE AA were likely only when the finished water pH was at or below pH 7.5 (Kempic,2000). Even in this pH range, the media may need to be replaced more frequently than once a year,which would make the option very expensive especially compared to the POU AA option. The runlength data used for this analysis were from a site with very little competing ions (Simms and Azizian,1997). Studies at other sites with higher levels of competing ions have much lower run lengths(Clifford et al, 1998). Based on the limited finished water pH range where POE AA might beeffective and that the POU media needs replacing much less frequently due to lower water demand,POE AA has not been listed as a compliance technology. POE devices that utilize media that are lesssensitive to pH adjustment may be listed as compliance technologies in the future once data on theirperformance is generated.However, because the volume of water treated by POU AA is much smaller, POU units havetypically have longer run lengths and require less frequent replacement than POE units. Therefore,the costs of POU AA treatment were considered in the final rule. The cost of replacement for POUAA is also much lower than POE AA.5-12