Technologies and Costs for Removal of Arsenic From Drinking Water

The arsenic loaded onto the column is:As loading = [(305,177)(0.375)(1/1000)](0.375)(1/1000)(750)(1000)As loading = 0.41 mg As/g AA {Table 2 of Phase 3 Report lists 0.43 mg As/g AA}B. Using the bed volume size of 16,032 liters, yields the following adsorptive capacities:As ads = (92,052 Fg*BV/L)(16,032 L/BV)(1 gram/10 6 Fg) = 1476 gramsAs tot = (98,040)(16,032)(1/10 6 ) = 1572 gramsIt appears that the adsorptive capacity of 1573 grams in the Arsenic Treatment EvaluationReport is based on total arsenic instead of the adsorbed arsenic.C. The maximum run length will be based on an adsorptive capacity of 1476 grams in the secondcolumn. For this step of the analysis, it will be assumed that all of the arsenic passing throughthe first column will be adsorbed by the second column. This is a very conservative estimatebecause the second column will also have leakage through it and concentrations will rise untilbreakthrough is reached at 2 Fg/L. This is balanced by the fact that when the polishing columnis moved into the roughing column position, some of its capacity will have already been usedwhen it was the polishing column. Both of these factors will be addressed later. The integralequation in step 2 is again utilized to estimate the amount of arsenic passing through the firstcolumn. When this value is equal to 1476 grams, then the maximum run length can bedetermined.For a run length of 18,500 BV:As pass = (2*10 -8 )/3*(18500) 3 + 0.0001*(18500) 2 + 0.8394*18500As pass = 1474 gramsD-16