An Automated Electrophoretic Mobility Instrument for Coagulant Dose Control

Drinking water filtration plants nationwide are failing to adequately reduce the public health risk due to exposure to sometimes lethal Cryptosporidium and other microbial particle levels. New regulations also will require reduction of dissolved organic carbon (DOC) to minimize the risk from potentially carcinogenic reaction by-products resulting from disinfection. Particle and DBP precursors are controlled most cost effectively with chemical coagulation and filtration. Although operator skill has been sufficient in the past, new process control instrumentation becomes imperative as new regulations force plants to operate closer to their maximum performance capabilities. Chemical coagulation is used to control public health risk by removing particles and DOC. Coagulation must be optimized in a site-specific manner at each individual treatment plant and continuously maintained at the optimum. Operators do not currently have an online coagulant dose control detector that is calibrated and has the capability to derive new set point values from jar test results, which represent frequently changing conditions. The instrument to be developed under this Phase I project employs automated electrophoretic mobility, which meets the deficiencies of current instrumentation. It consists of a new innovative optical/electrical/mechanical measurement scheme resulting in a potentially reliable, low-cost, robust instrument that can be recalibrated in the field. This technology could provide operators nationwide with continuous, optimum settings of the most critical performance variable fundamental to running a high performing facility.