Application of Turbidity Meters for the Quantitative Analysis of Flocculation in a Jar Test Apparatus

摘要

Turbidity is an important water-quality indicator as it not only indicates the presence of suspended solids but also shows the possible presence of algae, microorganisms, organic matter, and microparticulates. Generally, turbidity is removed through two very important steps in a typical water treatment process: coagulation and flocculation. At lab scale the measurement of flocculation activity may often be difficult and imprecise because reproducible water samples need to be taken offline and inserted into a turbidity meter or spectrophotometer, while the standard jar test system is relatively imprecise and measurements discontinuous and/or subjective. To allow routine quantification, an online quantitative method for the analysis of flocculation activity was developed, which can measure sedimentation as a function of time. This method involved modification of a standard, commercial jar test apparatus by the addition of six turbidity meters coupled with a data-acquisition system operating with LabView software. This system has been tested using a standard reference turbid water suspension containing kaolin, with aluminium sulphate and ferric sulphate as coagulants. (C) 2015 American Society of Civil Engineers.