Gravity-Powered Chemical Dose Controller for Sustainable, Municipal-Scale Drinking Water Treatment

Abstract

Accurate chemical dosing in water treatment plants is imperative to ensure optimal efficiency of flocculation and disinfection. Design algorithms, calibration techniques, and standardized components are presented for a linear flow orifice meter (LFOM) and a linear chemical dose controller (LCDC). These coupled systems allow water treatment plant operators to easily and reliably set and maintain the desired doses of coagulant and disinfectant. The combined system adjusts the chemical flow rate automatically in response to changes in plant flow rate to maintain the target chemical dose. The LFOM maintains a linear relationship between height of water in the entrance tank and plant flow rate. A lever and float are used to create a direct relationship between the plant flow and chemical flow produced by the LCDC. A linear relationship between head loss and chemical flow in the LCDC is created by using the major head loss through a small diameter tube to control the chemical flow rate. Experimental tests are described that minimize minor losses and verify performance of the LCDC.