Frank Owusu-Adarkwa, Julia Mertz, Ruju Mehta
Abstract:
Continuous, accurate chemical dosing is an essential part of AguaClara plant function. Proper dosing ensures effective flocculation, sedimentation, filtration and disinfection. The chemicals that must be added at different points during the water treatment process are coagulant (PACl or Alum may be used) and chlorine. The linear chemical dose controller (LCDC) is a device that the plant operator can use to directly set doses of coagulant and disinfectant based on the flow rate into the plant. Previous LCDC designs have only been configured to add coagulant prior to flocculation. The triple-doser design is capable of adding coagulant before the influent water enters the stacked rapid sand filter and of adding chlorine for disinfection before the treated water enters the distribution tank. The Spring 2012 team is introducing a more sophisticated LCDC device that will allow the operator to set and monitor the two doses of coagulant and the dose of disinfectant, for a total of three chemical doses, on a single dosing apparatus. In order to ensure accurate chemical dosing, we are testing and documenting the calibration of the new LCDC. Ultimately, we will determine a method for the triple-armed dosing mechanism to be built and added to plants on site, putting a focus on simplicity and elegance of design so that the AguaClara LCDC can be constructed with local resources.
