Modification of jar testing protocol combined with mEnCo model predicted dose to predict dissolved organic matter removal for surface water

Abstract

In recent climatic events in Australia, the need for frequent jar testing to determine optimum coagulant and flocculant aid doses became apparent in order to determine optimum treatment efficiencies. The generally applied jar test procedure can be time consuming and this prompted investigations for capacity to test waters more rapidly, for a range of treatment conditions and raw water qualities. The aim of the study reported here was to develop a rapid procedure for determination of dissolved organic matter (DOM) removal, measured as dissolved organic carbon (DOC) and UV absorbance (254 nm/cm) for a range of treatment conditions (coagulant dose and pH). Using a previously established predictive model (mEnCo) for coagulant determination, several coagulant doses were then predicted for application in a modified jar test protocol. Best fitted and predicted data using the exponential decay function compared with data from a 6× jar test procedure were obtained using three doses, 0.5× EnCD, EnCD and a VHD (≥2× EnCD). It is proposed that this procedure may be used to more rapidly determine treatment efficiency based on the removal of organics compared with traditionally applied jar tests.