Technologies and Costs for Removal of Arsenic From Drinking Water

For design flows greater than 1 mgd, the building cost varied based on flow from $100 to $90per square foot.Design Assumptions: Capital Costs with pH AdjustmentFor two options, the water pH is adjusted to the optimal pH of 6. The capital cost equationfor the pH adjustment module, which includes post-treatment corrosion control is given by thefollowing equation (Appendix D provides additional information):Capital cost = 40517 * Design Flow + 31889Design Assumptions: O&M Costs with and without pH AdjustmentThere are three major components to the operation and maintenance (O&M) costs -replacement media, energy and labor.1. The critical variable in calculating the replacement media costs is the run length - the numberof bed volumes until the effluent concentration exceeds a specific concentration. The runlength for the natural pH range of 7 # pH < 8 is 10,000 bed volumes (BV). The run length forthe natural pH range of 8 # pH # 8.3 is 5,200 BV. These run lengths are used to estimate thereplacement of the activated alumina in half of the active columns.2. The O&M costs were calculated at 2 run lengths when pH is adjusted to pH of 6. The two runlengths that were selected for the optimal pH of 6 are 15,400 and 23,100 BV.3. Chemical costs also are incurred to adjust the pH. The following equation was used forchemical costs for pH adjustment:Chemical cost (pH adjustment) = 81361* Average Flow + 151.74. The second major component in the O&M costs is incremental labor cost. Incremental laboris the labor associated with the additional maintenance that comes with a new process.3-39