A NEW CHARGE BASED COAGULANT DOSE CONTROL INSTRUMENT

The catastrophic drinking water treatment plant failure in March 1993 in Milwaukee was a direct result of the inability to control coagulant chemical dosage during significant changed in raw water quality. This event largely dispelled the myth that only small water utilities were vulnerable to such control problems. The current state of this critical technology, coagulant dose control, is woefully inadequate. The Milwaukee failure is traceable to the inadequate tools plant operators have available to deal with this daily on-going problem at every plant site. Optimization with the jar test, a trusted standard feedforward control method, is skill and labor intensive, too slow, and too insensitive for many modern water treatment plants. Streaming current detectors - the sole automated feedback controller - cannot be calibrated to a known reference and requires skilled technicians to set and maintain control. A new coagulation control concept was demonstrated in Phase I to be feasible for achieving both feed forward and feed back coagulant control. This utilizes a technique called colloid charge titration, but with a unique new method of end-point detection. Clear Corporation Enterprises, Inc.'s Phase II objectives are (1) design a prototype instrument capable of proof in field test based on applicability proven in Phase I, (2) implement the innovative new end-point detection and feedforward/feedback technique in a rugged easy to use and affordable design, and (3) validate system performance at a municipal water treatment facility. The proposed program is attractive because it could address a seemingly intractable, critical control problem which has plagued the drinking water industry nationwide throughout is history. This device, if proven effective, could provide operators even in small facilities with the means to prevent catastrophes like Milwaukee's.