This Small Business Innovation Research (SBIR) project will employ Nanofiltration to generate sulfate ion feedstocks and high current density on-site generation (synthesis) of the powerful oxidant peroxodisulphate ("persulfate") with novel, high reliability boron-doped untrananocrystal-line diamond (UNCD) electrodes to dramatically lower the cost of unconventional fossil fuel (FF) waste water remediation. The development of shale gas (via "fracking"), oil sand and off-shore oil production typically generate vast quantities of wastewater. Much of this water is contaminated with by-products of FF production such as napthenic acids, phenols, poly-aromatic hydrocarbons, heavy metals and other treatable toxins which lead to groundwater/surface water contamination, costly regulatory compliance issuesand the threat of lawsuits. The huge oil sand wastewater tailing ponds near Fort McMurray, Alberta, which are representative of vast unconventional US hydrocarbon resources (e.g., Green River, UT), are rendered toxic principally by napthenic acids at<100 ppm. Treatment and/or re-use of FF wastewater have, therefore, become a costly necessity. An improved method of FF wastewater remediation would, therefore, be a critical enabler for future energy conservation. Nanofiltration is a mature, inexpensive technology which is capable of separating sulfate feedstock from local brackish ground or seawater. Persulfate is a highly effective oxidant for destruction of toxic organic contaminants in groundwater. The main barrier to its widespread usage had heretofore been the high cost of persulfate synthesis on the platinum (Pt) electrodes now used for persulfate synthesis and the cost/difficulty of transporting persulfate to producer sites. Previous NDF-funded research ADT has already demonstrated the UNCD is able to withstand very high current densities for anodic oxidation, e.g., ~1.0 A/cm2, which delivers a lower CAPEX per pound of persulfate as compared to PT at higher current efficiency and at a substantially lower cost per electrode than Pt. A cost analysis for On-site Generation of persulfate on UNCD electrodes indicates that wastewater contaminated with napthenic acid in the range of<100-200 ppm can be remediated for less than $1.00 per barrel,<$6/tonne of water, allowing direct water reuse. Given the diversity of energy industry wastewater and groundwater remediation applications for persulfate, e.g., refinery and oil storage site remediation, the potential market for water treatment systems with UNCD electrodes should exceed several $billion in the US alone. It is also applicable to oil-spill remediation for which large volumes of contaminated water could be cost-effectively treated with persulfate synthesized on UNCD electrodes from sulfate-feedstock nanofiltered on-site from seawater.
