Technologies and Costs for Removal of Arsenic From Drinking Water

3. Empty Bed Contact Time (EBCT) is 5 minutes per column4. The estimated cost of the activated alumina media is $0.82/lb for systems with a design flowgreater than 0.1 mgd. The estimated cost of activated alumina media is $1.30/lb for systemswith a design flow less than or equal to 0.1 mgd.5. The density of the activated alumina media is assumed to be 47 lb/ft 3 .6. The bed depth assumption ranged from 3 to 6 feet, depending on the design flow. Themaximum diameter per column was 12 feet. When the calculated media volume exceeded themaximum, the treatment media was divided into several beds to maintain a realistic beddiameter. Thus, larger designs include multiple activated alumina trains, each treating aportion of the total flow.7. The vessel cost has been sized based on 50 percent bed expansion during backwash eventhough backwashing may not be necessary on a routine basis for smaller systems. The vesselvolume was calculated as (1.5)(media volume). The vessel cost is given by the followingequation:Cost = 63.288 * (Vessel Volume in gallons) ^ 0.6798. The capital costs include a redundant column to allow the system to operate while the mediais being replaced in the old roughing column.9. The remaining components of the process equipment include concrete, pipe and valves andelectrical and instrumentation. A cost factor of 14.43 percent of the manufactured equipmentand activated alumina was used for these other construction cost components.10. The capital costs have been estimated from the total process costs using a factor of 2.5 forsmall systems and 3.33 for large systems.3-37