Application of microfiltration for the treatment of Marcellus Shale flowback water: Influence of floc breakage on membrane fouling

Abstract

Management of Marcellus Shale flowback water is a rising concern in Pennsylvania. Due to limited capacity for wastewater disposal by deep-well injection, flowback water reuse is the dominant management option in PA. Microfiltration is a promising technology to be used in a mobile treatment system for solids removal from Marcellus Shale flowback water prior to reuse. It was found previously that early Marcellus Shale flowback water could cause severe membrane fouling due to the presence of stable submicron colloids. Bench-scale cross-flow filtration system was used in this study to evaluate the feasibility of microfiltration for treatment of Marcellus Shale flowback water that does not contain these submicron colloids. The performance of alumina (Al2O3) and silicon carbide (SiC) ceramic membranes that have distinct surface charge properties was evaluated in this system using a constant transmembrane pressure. The difference in the isoelectric point of these membranes suggested possible differences in fouling behavior, but extremely high salinity of the flowback water screened the electrostatic interactions and minimized these differences.For the two flowback waters tested in this study, the one with lower TDS caused more severe fouling of both SiC and Al2O3 membranes during the first 15min of filtration. The flux decline analysis revealed that intermediate pore blocking was the dominant fouling mechanism in the early filtration stage. Such behavior was due to the fact that the particulate matter in this flowback water was in the aggregate form and the flocs were prone to breakup at elevated shear stress caused by high pumping rate. Despite having much higher TSS, the other flowback water did not cause excessive membrane fouling due to stability and strength of its original particles.