The project proposes to treat “produced water”, a by-product of oil/gas extraction, with the FARADAYIC Electrodialysis Process followed by reverse osmosis (RO) treatment. Successful implementation of this technology will enable enhanced ionic removal, which, in turn, will ultimately permit the reuse of produced water. The tangible benefits will be two-fold: (1) lower water treatment power requirements and (2) reduced membrane fouling tendencies.
Faraday Technology, Inc., Clayton, OH
Sustainability of oil and gas supplies continues to be of great importance to the United States and other countries around the world. U.S. domestic oil and gas reserves have become increasingly important as the country attempts to achieve foreign energy source independence. Produced water is a by-product of oil and gas extraction. This waste water stream may contain salinity, oil, grease, organics, metals, radioactive materials, bacteria, and other pollutants as well as chemical additives used during the oil/gas recovery processes. Underground injection has traditionally been the most common strategy to manage produced water in onshore production facilities. Development of a produced water treatment strategy, permitting beneficial water reclamation, is anticipated to ultimately lower the cost of oil and gas production.
Innovative approaches are needed to treat the significant volumes of produced water generated annually in the United States. The project proposes to treat produced water by utilizing the FARADAYIC Electrodialysis Process to reduce high salinity levels. Next, it is proposed that the water be treated by Reverse Osmosis (RO), which will remove dissolved organics, bacteria and other produced water contaminants. During the FARADAYIC Electrodialysis Process a pulsed electrolytic field is tuned to achieve enhanced ion transport as well as reduced boundary layer thickness for improved transport efficiencies across electrodialysis membranes. A reverse pulse may be applied to limit the occurrence of membrane fouling. The FARADAYIC Electrodialysis Process is anticipated to have lower power requirements than the alternative, DC Electrodialysis, making the process more economically attractive.
A process to treat produced water for reuse and recycling applications is attractive from both economic and environmental standpoints. A cost effective method for treating produced water would be environmentally friendly, enabling reuse for applications such as irrigation, drinking water, and the creation of habitats for livestock and wildlife. Potentially beneficial industrial uses include dust control, vehicle/equipment washing, power generation and fire control. In the last half century, global demand for freshwater has doubled about every 15 years and has placed existing freshwater resources under great stress. It has become increasingly difficult and expensive to develop new freshwater resources. Recycling of treated produced water would free-up significant volumes of unpolluted fresh water and provide an alternative water source for the relief of semi-arid and arid regions of the Earth. Introducing recycled produced water for irrigation alone would reduce the fresh water requirements of farmers who world-wide use approximately 150 billion gallons of fresh water per day. Turning waste water into a valuable resource would be beneficial not only to the oil and gas industry, but to the world as well.
The ion selective electrodes were characterized and calibrated for the range of solutions tested. Direct current tests have been conducted in a half-cell to study transport under DC conditions at varying current densities. Researchers also evaluated agitation of the solution at varying RPM under DC conditions (single current density used for all agitation evaluation tests).
The team has conducted transport studies using pulse current electric fields and has established an initial pulse current test matrix to evaluate the effects of peak currents, duty cycles, and frequencies. The results from this test matrix were used to fine tune and experimentally optimize the electric filed parameters for multi-component tests, such as those from simulated produced water compositions. Appropriate produced water compositions have been identified for coal-bed methane operations, and these compositions were tested with pulse current and direct current electric fields. The monovalent ion transport tests show similar results with DC and pulse electric fields. Experiments with divalent species were conducted with the electric field optimized to enhance ion transport with the pulsed fields.
The effects of organic phases on membrane fouling were studied as part of this project. Sodium and calcium ion transport experiments were performed using a cation selective membrane and simulated Powder River Basin produced water with organics added. The tests were performed under direct current (DC) and pulse current (PC) conditions. A slight Increase in sodium ion transport was observed with PC under certain conditions. Results indicated that PC electric fields may indeed deter membrane fouling.
Phase I of this project ended April 19, 2010.