Characterization of silica and dissolved organic matter aggregation in SAGD produced water

Abstract

Proper understanding of SAGD produced water and boiler blow down (BBD) water in particular is required to propose effective treatment processes for reuse and reduction in the quantity of disposable water. BBD contains high dissolved organic matter (DOM) and total dissolved solid (TDS). This study investigates the interaction of silica and DOM in BBD using different analytical techniques. The roles of different types of organics, salts, and colloids on silica-DOM co-precipitation were studied at different concentrations and pH. In order to study the effects of all factors at three levels and to deter- mine the most influential parameters with a minimum number of experiments Taguchi orthogonal array was employed. Analysis of variance (ANOVA) was performed to evaluate the contribution of each parameter. In the presence of salt, the rate of silica organic co-precipitation varies with the nature of organics. Humic-like fractions of DOM plays a major role in the process of DOM-silica co-precipitation. Light scattering technique applied to examine the aggregation rate at low concentrations of organics and DOM also demonstrates that the presence of organics enhances silica aggregation rate.