Technologies and Costs for Removal of Arsenic From Drinking Water

3.5.2 ChlorinationAs previously stated, chlorination can cause DBP formation in source waters with high TOCconcentrations. Chlorination has also been shown to cause fouling in some membrane processes. Asa result, source water characteristics and downstream process needs should be thoroughly evaluatedwhen considering chlorination as an oxidation technology. Capital and O&M costs were developedfor cylinder and tank feed chlorination systems at dosages of 1.5 mg/L. Similar to potassiumpermanganate systems, the VSS Model was used for calculating costs for the flows below 1 mgd, andthe W/W Cost Model was used to estimate the capital and O&M costs for flows greater than 10 mgd.Linear regressions were used to estimate costs in the transition regions between the models, i.e., 1 to10 mgd. The following are some highlights of the system design used at the time of cost estimation:# For very small systems, chlorination is accomplished with a hypochlorite feed systemcapable of providing dosages to 10 mg/L as chlorine. The system is equipped with a 150gallon storage tank and utilizes a 15 percent sodium hypochlorite feed stock.# The VSS Model makes provisions for building (52.2 percent), fencing (60.5 percent), androad (41.4 percent) costs associated with chlorine addition. Housing costs are onlyneeded when the arsenic removal process is a centrally-managed point-of-use option.Otherwise, it is assumed that chlorination process would be housed in the same buildingas the larger central treatment process.# Capital costs were calculated for both with and without housing costs added.# Incremental labor requirements for O&M costs were assumed to be 1 hours per week.# For small systems, cylinder feed chlorination system capital and O&M costs wereestimated.It should be noted that some systems currently using chlorine for disinfection may be able tomodify existing chlorine feed systems to utilize chlorine as a preoxidant with significant capital costsavings. Capital and O&M cost curves and equations are presented in Figures 3-1 and 3-2.3-20