An Evaluation of DAF Clarification Laboratory Test Methods

Jar testing is commonly used to predict the clarification performance of process additives. Turbidity and total suspended solids measurements (TSS) are often used to gauge jar test performance. This work documents the precision with which turbidity and TSS measurements can be made. These are demonstrated to be relatively imprecise measurements. Data are also reported which define the strength of the correlation between these two variables. The reported experiments improve the understanding of the relationships between the independent variables of jar test shear rate, mixing time, settling time, temperature, and polymer dose and the dependent variables of supernatant turbidity and TSS. Experiments were performed upon a variety of recycled fiber process filtrates. The data demonstrate that manipulation of independent jar test variables has a profound impact on the predicted performance of polymeric treatment systems. The Orchidis Flotatest is a laboratory dissolved air flotation (DAF) tester. Experiments were performed to compare the predictive capabilities of laboratory DAF testing versus conventional jar tests. A variety of filtrates were tested via both methods. Data and discussion show that laboratory dissolved air flotation testing gave some unique predictive capabilities not present in jar test results. However, it was concluded that jar testing was still a valuable primary tool for determining relative treatment performances.