THWRC Awarded Proposal 515UHH0048H

Project Number:       515UHH0048H

Title:                             Recycling of Hydraulic Fracturing Wastewater Using Integrated New Microbial

                                       Fuel Cell (MFC) Technology and Modeling

Lead PI:                     Cumaraswamy Vipulanandan

Awarded Amount:    $27,500

ABSTRACT

Rapid development of unconventional natural gas resources in the deep shale is expanding in Texas and 28 other states in the U.S. with about 35,000 wells hydraulically fractured annually. But water management has emerged as a critical issue in the development of these inland gas reservoirs. Following hydraulic fracturing, large volumes of water containing very high concentrations of total dissolved solids (TDS) and oil are returned to the surface. The TDS concentrations in the wastewater, also known as “flowback,” can reach 2 to5 times that of sea water. Wastewater that contain high TDS levels are challenging and costly to treat with currently used technologies such as electro-coagulation (EC) and dissolved air floatation (DAF) which have many limitations. Economical production of shale gas will require creative management of flowback fluid to ensure protection of groundwater and surface water resources. Recycling of treated flowback fluid will save up to 40% of the volume of water currently being used and also enable environmentally sustainable and economically feasible natural gas extraction. Hence there is an urgent need for developing cost effective recycling treatment technologies for the flowback fluids.

Microbial fuel cell (MFC) technology represents the most recent approach for treating wastewater and also generating electricity – bioelectricity from biomass during selected bacterial activities. The uniqueness about the MFC is that there can be oxidation in the anode chamber and reduction in the cathode chamber. If the MFC is properly designed, the anode chamber can also produce the needed bioflocculent/biosurfactant to enhance the precipitation of the suspended solids. The cathode chamber will be used to rapidly precipitate the dissolved metals in the wastewater. Preliminary studies at the University of Houston have shown promising results, where the MFC reduced the salt content in the wastewater and also produced bioelectricity. Based on this study, the standard MFC configuration has to be substantially improved to handle higher levels of TDS and rapidly treat and recycle the flowback fluid.

The overall objective of this study is to develop and design a new integrated MFC with pre and post treatments to completely treat the wastewater that has high levels of oil contaminated TDS. Both field and laboratory simulated wastewater samples will be used in this study. The new pretreatment that was recently developed at UH will rapidly remove the dissolved salts by precipitating metals and chlorides.  The new concentric cylindrical configuration of MFC will be used to rapidly treat the pretreated wastewater for the following reasons: (1) produce bioflocculants/ biosurfactants to rapidly precipitate the fine suspended solids in the anode chamber; (2) reduce the dissolved solids and precipitate them in the cathode chamber; (3) recycle the treated wastewater and (4) produce bioelectricity to power the need electrical appliances (sensors, controls). The new integrated MFC configuration developed in this study will be easy to adopt in the field sites. The research study has been divided into five distinct Tasks to achieve the stated objective. In Task-1 methods will be developed to pre-treat the wastewater to remove the dissolved solids and the large size suspended solids. In Task-2, the focus will be on optimizing the architecture of the MFC chambers to rapidly precipitate the fine suspended solids in the anode, remove the remaining dissolved solids in the cathode and produce electricity.  In Task-3, methods will be developed to post treat the treated flowback fluid to enhance the fracturing performance (including viscosity). Numerical modeling of the new MFC is planned in Task 4. Cost/benefit analysis of the new MFC is planned in Task-5. The researchers will closely work with the oil servicing company to obtain the field samples and the study will be completed in two years.