Technologies and Costs for Removal of Arsenic From Drinking Water
Technologies and Costs for Removal of Arsenic From Drinking Water
Technologies and Costs for Removal of Arsenic From Drinking Water
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3.3 ADDITIONAL CAPITAL COSTSThe cost models discussed in the previous sections are good tools <strong>for</strong> estimating capital <strong>and</strong>O&M costs associated with various drinking water treatment technologies. There are additionalcapital costs, however, which the models do not account <strong>for</strong> <strong>and</strong> may be a very real expense <strong>for</strong> publicwater utilities. The need <strong>for</strong> additional capital costs can be affected by a number <strong>of</strong> factors, including:contaminants present, quality <strong>of</strong> the source water, l<strong>and</strong> availability, retr<strong>of</strong>it <strong>of</strong> existing plants,permitting requirements, piloting issues, waste disposal issues, building or housing needs, <strong>and</strong>redundancy. Tables with additional capital cost estimates <strong>for</strong> each technology discussed in thisdocument are presented in Appendix E.Contaminants<strong>Arsenic</strong> is typically present in drinking water in one <strong>of</strong> two oxidation states, As(III) or As(V).As(V) is more effectively removed by each <strong>of</strong> the removal technologies discussed in this document.However, As(III) can be easily oxidized to As(V) using chlorination, potassium permanganate, orother methods. Groundwaters typically contain As(III), while As(V) is more commonly found insurface waters.The presence <strong>of</strong> additional contaminants, <strong>for</strong> example, inorganics (sulfate, aluminum,manganese), pathogenic contaminants (Giardia, Cryptosporidium), or organic contaminants(trihalomethanes, haloacetic acids), can raise additional treatment concerns <strong>and</strong> result in decreasedprocess per<strong>for</strong>mance. Changes in coagulant dosage or type, sedimentation time, or membraneefficiency are just a few <strong>of</strong> the concerns that may arise. Presence <strong>of</strong> pathogens can result in a need <strong>for</strong>disinfection <strong>of</strong> finished water. Selection <strong>of</strong> treatments that reduce additional contaminants wouldgenerate additional benefits from the treatment technology.L<strong>and</strong>L<strong>and</strong> costs are not included as part <strong>of</strong> the construction <strong>and</strong> capital costs <strong>for</strong> installation <strong>of</strong> newfacilities. L<strong>and</strong> costs <strong>and</strong> the amount <strong>of</strong> l<strong>and</strong> needed will vary significantly from site to site.Technology selection <strong>and</strong> the footprint <strong>of</strong> the technology will also play a critical role in l<strong>and</strong> needed<strong>for</strong> treatment. The November 1999 Technology <strong>and</strong> Cost Document presented ranges <strong>of</strong> costs basedon the Technology Design Panel recommendations. Comments on the proposed rule provided verylittle documentation on l<strong>and</strong> costs <strong>for</strong> compliance with arsenic. One comment from the Association3-13
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