On April 19, 2013, EPA proposed revisions to the effluent limitations, guidelines and standards that would strengthen the existing controls on water discharges from steam electric power plants. The rules would require power plants to install pollution control technology and implement waste-treatment procedures in a phased approach between 2017 and 2022. The EPA must finalize the rules by May 22, 2014. The rules apply to all water discharged from steam power plants, but a particular concern is FGD wastewater. The pollutants of concern include mercury, arsenic, selenium, nitrogen and total dissolved solids.

Over the next few years, plant operators will be upgrading their existing SO₂ control systems and installing new systems to meet the new emission limits posed by the utility MATS and CASPR (when finalized).  The great majority of existing systems are wet FGDs and it is likely that most new FGDs will be wet because it is difficult for a dry system to meet the new emission limits. These wet FGDs utilize large quantities of water with limestone to remove the SO₂.  The proposed water discharge rules as well as increasing regulations limiting the availability and use of water will be of great concern to operators of existing wet FGDs and those power plants considering installation of new FGDs.

It is not an easy task to design an FGD wastewater treatment system that meets or exceeds discharge regulations because the quantity and composition of FGD discharge water varies widely based on the boiler rating, scrubber type, the efficiency of flyash removal, the efficiency of the dewatering system and the composition of the coal, limestone and make-up water used.  Most FGDs discharge purge or wastewater that is a slurry of water, dissolved solids and suspended solids laden with heavy metals and salts.

The following speakers will describe the options available to plant operators utilizing or considering wet FGDs to achieve the discharge limits and reduce water usage and discuss their experience with developing, testing, designing and troubleshooting treatment technologies for FGD wastewaters, the advantages and disadvantages of the currently available options including capital and operating costs and the latest state-of-the-art technologies for treating, minimizing or eliminating the wastewater that is generated by wet FGD systems.

Paul Chu, Project Manager at the Electric Power Research Institute, will present the work EPRI has been doing to evaluate wastewater treatment options. EPA recently proposed numeric limits for selenium, mercury, arsenic and nitrate/nitrite for FGD wastewaters. As power plants require cost-effective and reliable treatment options, EPRI has been conducting treatment evaluation studies in the laboratory, pilot and full-scale.  EPRI’s work has focused upon physical/chemical precipitation and adsorption based technologies as well as biological reduction approaches.

Norikazu Inaba, Manager of Process Engineering at MHIA /Advatech (A URS & MHIA Company), will discuss "Simple Zero Liquid Discharge System for FGD Wastewater."  MHI has developed low CAPEX/OPEX technology for truly achieving zero liquid discharge (ZLD) from wet FGD to meet the stringent effluent limits. The Wastewater Spray Dryer (WSD) that eliminates a purge stream from the wet FGD process is easy to retrofit and requires no chemicals and significantly less energy than the conventional brine evaporator.

Gordon Maller, Principal Project Manager and Business Development Manager for URS Corporation – Process Technologies Office, will present "Wastewater Treatment and Zero Liquid Discharge Technologies – Overview and New Technology." New effluent limitation guidelines (ELG) have been proposed by the EPA which will require utilities to provide significantly higher levels of treatment prior to discharge for a number of wastewater streams in contact with coal combustion residuals (CCR) including FGD wastewater. This presentation will provide an overview of the new rules as well as an overview of existing and emerging WWT and ZLD technology to comply with the new rules. New technology and strategies for plants to operate as ZLD at a much lower cost, optimize water usage, and accomplish necessary improvements such as closing waste impoundments will also be discussed.

William A. Shaw, Senior Process Engineer for HPD^® Evaporators and Crystallizers at Veolia Water Solutions & Technologies North America, will present "Zero Liquid Discharge Systems for FGD Wastewater."   In light of proposed EPA Effluent Limit Guidelines, many coal-fired power plants are considering ways to reduce their water discharges. Zero liquid discharge (ZLD) processes are being studied in anticipation of even more restrictions on water discharges in the future. Closing the loop by adopting a ZLD treatment scheme will usually involve consideration of evaporation and crystallization technologies as these have had and will continue to play an important role in the recovery and re-use of water from industrial wastewater streams.  However, ZLD systems can be very expensive from both a capital and operational perspective.  New approaches to evaporator system design, especially the recently patented CoLD^® crystallization technology, provide additional options to power plants which are looking for methods to effectively and economically reduce or eliminate their water discharges from FGD scrubbers.   

To register for the August 15 "Hot Topic Hour" on "Control and Treatment Technology for FGD Wastewater" at 10 a.m. DST, click on: http://www.mcilvainecompany.com/brochures/hot_topic_hour_registration.htm.

On Thursday at 10 a.m. Central time, McIlvaine hosts a 90 minute web meeting on important energy and pollution control subjects. Power webinars are free for subscribers to either Power Plant Air Quality Decisions or Utility Tracking System. The cost is $125.00 for non-subscribers. Market Intelligence webinars are free to McIlvaine market report subscribers and are $400.00 for non-subscribers.

To register for the Hot Topic Hour, click on:

http://www.mcilvainecompany.com/brochures/hot_topic_hour_registration.htm.

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Bob McIlvaine
President
847 784 0012 ext 112

rmcilvaine@mcilvainecompany.com
www.mcilvainecompany.com