THWRC Awarded Proposal 513UHH0035H

Project number:          513UHH0035H

Title:                             Accelerated Treatment and Recycling of Hydraulic

                                     Fracturing Wastewater Using the Microbial Fuel Cell (MFC)

Lead PI:                       C. Vipulanandan

Awarded amount:      $30,000

 

Project Abstract

Development of unconventional, onshore natural gas resources in deep shale is rapidly expanding in Texas and many parts of the U.S. with about 35,000 wells hydraulically fractured annually. 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 return to the surface. The TDS concentration in this wastewater, also known as “flowback,” can reach 2 to5 times that of sea water. Wastewaters that contain high TDS levels are challenging and costly to treat and currently used technologies such as electro-coagulation (EC) and dissolved air floatation (DAF) have many limitations. Economical production of shale gas resources will require creative management of wastewater to ensure protection of groundwater and surface water resources. With global concerns over the quality and quantity of fresh water, novel water management strategies and treatment technologies that will enable environmentally sustainable and economically feasible natural gas extraction will be critical for the development of this energy source.

Microbial fuel cell (MFC) technology represents the most recent approach for treating wastewater and also to generate electricity – bioelectricity from biomass during bacterial activities. The uniqueness about the MFC is that there can be bio-electrochemical oxidation in the anode chamber (similar to EC) and reduction/air flotation in the cathode chamber (similar to DAF), combined parallel operation. If the MFC is properly designed in the anode chamber there will be also the production of needed bioflocculants to enhance the precipitation of the suspended and dissolved solids. The cathode chamber will be used to rapidly precipitate the dissolved metals in the wastewater. Ongoing studies at the University of Houston, where MFC is used to not only produce bioelectricity while recycling used-vegetable oil to produce biosurfactant in the anode chamber but also to treat contaminated water in the cathode chamber. By having multiple benefits, proposed MFC will have greater potential to be adopted in rapidly treating and recycling the wastewater from hydraulic fracturing.

The overall objective of this study is to design MFCs to treat the wastewater that has high levels of TDS. Both field and laboratory simulated wastewater samples will be used. The new MFC will be used to rapidly treat the pre-treated wastewater for the following reasons: (1) produce bioflocculants to rapidly precipitate the fine suspended solids and part of the dissolved solids in the anode chamber; (2) further reduce the dissolved solids and precipitate or air float them in the cathode chamber (3) recycle the treated wastewater and (4) produce bioelectricity to power the need electrical appliances (sensors, controls). The MFC configuration developed in this study will be easy to adopt in the field sites. The research study has been divided into four distinct Tasks to achieve the stated objective. In Task-1, methods to pre-treat the wastewater to remove the large size suspended solids (diameter greater than 0.5 mm) and also necessary ingredients to enhance the bioflocculants production in the anode chamber. In Task-2, the focus will be on optimizing the architecture of the anode chamber to rapidly precipitate the suspended solids and part of dissolved solids.  In Task-3, design of the cathode chamber will be optimized to precipitate/air float the dissolved solids. Also methods to improve the performance of the salt bridge will be studied. Cost/benefit analysis of the new MFCs is planned for Task-4. The researchers will closely work with few oil servicing companies to obtain field wastewater samples and the study will be completed in two years.