EAGER: Engineering Microbial Mats for the On-Site Treatment of Wastewater from Unconventional Gas Production

University Of Pittsburgh, Pittsburgh PA

Investigators

Abstract

CBET 1353858 Bibby University of Pittsburgh The proposed project proposal seeks to develop a novel, on-site, and low cost treatment mechanism for wastewaters produced during unconventional gas operations by engineering microbial mats. Wastewaters produced by unconventional gas drilling operations, termed produced wastewaters, contain both additives to assist in gas extraction and extremely high levels of total dissolved solids (TDS) originally derived from subsurface formations. The unique characteristics of wastewaters from unconventional gas production methods make treatment and disposal of this waste stream a significant and currently unsolved technical challenge. Microbial mats are agglomerated and layered bacterial consortia with complex internal chemical and energetic gradients and a high diversity of specialized microbial metabolisms. The characteristics of microbial mats, namely high salt stress tolerance, fixed nature facilitating transport and removal, and multiple mechanisms of contaminant removal, i.e. biologically induced precipitation, mineralization, or biosorption, suggest their utility in treatment of produced wastewaters. The goal of this technology is to treat produced wastewater well enough for reuse in fracturing operations, protecting water resources from over exploitation and minimizing the impacts of disposal. In order to reuse produced wastewater, drillers are primarily concerned with constituents that may cause scaling or foul a well, namely barium, strontium, iron, and biological fouling. Additionally, drillers are concerned about the accumulation of naturally occurring radioactive material (NORMs). All available data suggest microbial mats as a successful treatment scheme for removing constituents of concern from produced wastewaters; however, the application of microbial mats for the treatment of produced wastewaters is entirely novel and this work will serve to demonstrate both its feasibility and potential. Unconventional gas production, often termed ?fracking? for hydraulic fracturing, uses new technology to access gas trapped in geological formations that were previously inaccessible. The cost effective, domestic production of natural gas has significant economic benefits in a wide range of US industries. However, the management of wastewaters produced during hydraulic fracturing, termed ?produced wastewaters?, is a currently unsolved technical challenge. The salt content of produced wastewater is approximately five times that of ocean water and each well produces 2-4 million gallons of wastewater. Existing technologies are unable to cost effectively cope with this salt content and volume. This project will investigate a novel on-site treatment technology, microbial mats, for the treatment of produced wastewaters prior to reuse in future hydraulic fracturing operations. Microbial mats represent a novel treatment technology that would require minimal energy input and maintenance, and could be deployed onsite to eliminate the impacts associated with trucking large volumes of water for treatment.