In an area of increasingly critical importance to coal producers in Appalachia, Envirogen Technologies Inc. announced March 14 that it has introduced a new small-footprint fluidized bed reactor (FBR) system designed to treat low flows of selenium-laden coal mining waters economically and efficiently.
The new systems will allow coal mine operators to treat flows that start at less than 100 gallons per minute (gpm) to lower than 5 micrograms per liter selenium at discharge – even in the presence of high levels of nitrate. These systems can be automated and delivered in standard-sized ISO containers to difficult-to-reach locations that require minimal site preparation and engineering, and can be monitored remotely, Envirogen noted. The new small system FBR approach offers mine operators the ability to treat selected mining water outfalls with a relatively low initial capital expenditure and the flexibility to relocate the systems when needed.
Envirogen said it entered the coal mining selenium treatment business in 2011 with its FBR technology, which has been deemed “best-in-class” for performance and cost effectiveness by an independent study developed for the North American Metals Council. The company now offers containerized and built-in-place FBR systems that can be sized to treat a wide range of flows and influent water compositions, ranging from under 100 gpm to over 3,000 gpm. Envirogen said it has recently completed several long-term operational studies with FBR systems in coal mining operations in Appalachia and Western Canada, demonstrating the effectiveness of the technology in the field.
David Enegess, Vice President, East Region for Envirogen, said the move to develop small FBR systems was motivated by the realities of treating selenium-containing wastewaters in coal mining operations that have multiple outfalls – often in remote locations – as opposed to a single option that would require the construction of a large, centralized facility.
“Coal mining is a very dynamic activity, often conducted in rough, remote terrain,” Enegess said. “Sometimes it is impractical to pipe all the selenium-containing mining waters to a single, centralized facility from both cost and logistics standpoints. The smaller-sized FBR can meet the treatment and discharge requirements of low-flow outfalls. It can be rapidly implemented with a minimal amount of civil engineering, automated and remotely monitored. … For mines that have multiple outfalls, we envision these being treated by individual small FBRs, with other activities – such as solids treatment and disposal, chemical supply and spare parts serviced from a lower cost centralized location.”
Patriot Coal looks for cheapest selenium solution
One of the coal operators with earliest exposure to increasingly stringent enforcement, under legal pressure from environmental groups, of water laws related to selenium is Patriot Coal (NYSE:PCX) at various operations in southern West Virginia.
As a result of a lawsuit filed by the West Virginia Department of Environmental Protection (WVDEP) in state court in West Virginia, Patriot’s Hobet Mining LLC unit entered into a settlement agreement with the WVDEP that required Hobet to pay fines and penalties with respect to past violations of selenium limitations under certain of its National Pollutant Discharge Elimination System (NPDES) permits, to meet certain compliance deadlines related to selenium discharge levels and to research, develop and implement selenium-control pilot projects.
The Ohio Valley Environmental Coalition (OVEC) and another environmental group sued Patriot’s Apogee Coal Co. LLC in 2007 and Hobet in 2008 in the U.S. District Court for the Southern District of West Virginia, alleging that Apogee and Hobet had violated water discharge limits for selenium in certain of their NPDES permits. In March 2009, the court approved two separate consent decrees that extended the deadline to comply with water discharge limits for selenium for the permits covered by both lawsuits to April 2010.
In September 2010, the court found Apogee in contempt for failing to comply with the March 2009 consent decree. The court found that Apogee had failed to exercise reasonable diligence in evaluating and identifying viable treatment technologies, which diminished its ability to achieve compliance. Apogee was ordered to install a FBR water treatment facility for three mining outfalls and to come into compliance with applicable selenium discharge limits at these outfalls by March 1, 2013. Also, Hobet was ordered to come into compliance with selenium limits under the Hobet Surface Mine No. 22 permit by May 1, 2013, Patriot said in its Feb. 23 annual Form 10-K report.
Also, the September 2010 ruling required that Patriot select a technology for one outfall at Hobet Surface Mine No. 22. In June 2011, Patriot selected FBR technology for this outfall because it could utilize the knowledge gained building the Apogee FBR facility and additional research was needed to resolve certain detailed design considerations for ZVI and Ion Exchange (IX) technology. In December 2011, the court agreed to a change to the selenium water treatment technology from FBR to ABMet technology at this outfall.
Patriot said it continues to design and seek permits for the Hobet ABMet facility and anticipates beginning construction on the facility in the first half of 2012. The estimated total expenditures for completing the ABMet water treatment facility is about $25m, which is much less than the estimated $40m to build the Hobet FBR facility.
February 2011 lawsuit put more pressure on Patriot
In February 2011, OVEC and two other environmental groups filed a lawsuit against Patriot, Apogee, Patriot’s Catenary Coal Co. LLC and Hobet, in the same U.S. District Court alleging violations of ten NPDES permits and certain mine permits. On Jan. 18, Patriot finalized a comprehensive consent decree with OVEC and the other two environmental groups, which sets technology selection and compliance dates for the ten permits included in this litigation on a staggered basis, allowing Patriot to continue testing certain technologies as well as to take advantage of technology that is still in development.
“Our liability to treat selenium discharges at the other outfalls not addressed in the September 1, 2010 ruling is based on the use of ZVI technology,” said the Patriot Form 10-K. “We have installed ZVI systems according to our original water treatment strategy, while also performing a further review of other potential water treatment solutions. Our water treatment strategy reflects implementing scalable ZVI installations at each of the other outfalls due to its modular design that can be reconfigured as further knowledge and certainty is gained. Initial pilot testing of ZVI technology began in 2008 and has identified potential shortfalls requiring additional research to resolve certain detailed design considerations. To date, ZVI technology has not been demonstrated to perform consistently and sustainably in achieving effluent selenium limitations or in treating the expected water flows at all outfalls. However, based on the flexibility of the scalable system for configuration adjustments, improvements in the system design and demonstrated success in reducing selenium at certain flows, we plan to continue to pursue the ZVI-based water treatment installations and determine whether modifications to the technology could result in its ability to treat selenium successfully at outlets identified in the February 2011 litigation.”
At this time, there is no definitive plan to install FBR, ABMet or any technology other than ZVI technology at the other outfalls not included in the September 2010 ruling as none of the other technologies has been proven effective on a full-scale basis, Patriot added. The comprehensive consent decree with the plaintiffs in the February 2011 litigation requires that Patriot select water treatment technology by category beginning with the first category in September 2012 and ending with the last category in September 2014.