Engineers' Society of Western Pennsylvania


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Tuesday, November 6

Technical Sessions – 8:00 A.M.-12:00 Noon

ASME Session: Water Treatment for Combined Cycle Plants

IWC Rep: Colleen Layman Scholl, P.E., HDR, Inc., Janesville, WI
Session Chair: Bob Bartholomew, Sheppard T. Powell Associates, LLC, Baltimore, MD
Discussion Leader: Vickie Olson, Honeywell Process Solutions, Sandy Springs, GA

This session highlights water treatment aspects of evaporative coolers, wastewater recycle systems, and steam/water cycle systems. Flow accelerated corrosion (FAC), iron monitoring methods, use of ammonia, organic amines and film forming products to control FAC and iron transport in air cooled condensers (ACC) and other components are discussed. The increase in cycling service impacts all of these systems and requires greater consideration during unit design, operation and treatment.

IWC 18-29: Living in Perpetual Drought – Operational Impact of Power Plant Design Features to Minimize Water
Daniel Sampson, HDR, Walnut Creek, CA

Two combined cycle power plants in the Western United States employ various design features to minimize water usage to the maximum extent possible. Both plants employ air-cooled condensers and evaporative coolers. Evaporative cooler blowdown, HRSG blowdown, and other plant waste streams are recovered and reused to the maximum extent possible. One plant includes wastewater recovery using a combination of membrane and thermal concentration. Inspections at both plants revealed flow-accelerated corrosion (FAC) in both the air-cooled condensers and in the drums of the LP HRSGs. Recycling of plant waste streams creates significant challenges for steam cycle chemistry. Contamination in recovered water, complicated treatment systems, and chemistries employed to minimize FAC contribute to operational challenges. Both plants have difficulty maintaining conductivity after strong acid cation exchange (CACE) within steam turbine vendor limits, for example. Frequent cycling at both plants created unforeseen impacts on steam cycle chemistry, water usage, and wastewater recovery systems. This paper examines water and wastewater minimization design features and their impact on the steam cycle and plant operation. It describes what worked well and what did not, providing readers with important recommendations specific to water and wastewater minimization strategies.

IWC 18-30: Evaporative Cooler Water Requirements – The Letter and the Intent of the Law
Brian Clarke, P.E., Caroline Wilson, E.I., Charles Statler, E.I., and Steve Russell, P.E., Kiewit Engineering Group, Inc., Lenexa, KS

Evaporative cooler water recommendations vary by manufacturer and are inconsistent related to constituents and achievable cycles of concentration. Following a brief overview of how evaporative coolers work, the limits of three manufacturers (GE, Siemens, MHI) will be evaluated and the intent of the limits will be discussed. Previous experience has shown some flexibility related to the standard limits and also that once systems are operating the facility often treats the evaporative cooler more simply than the design engineer intended.
This paper explores the goal of the evaporative cooler water guidelines and provides recommendations to design engineers and operators to optimize and protect evaporative cooler systems. Treatment options such as blending demineralized water, using RO permeate, using a calcite filter and chemical addition are reviewed.

IWC 18-31: Experience Using a Film-Forming Corrosion Inhibitor at RWE Generation UK’s Staythorpe Power Station
Daniel Cicero and Lionel Barre, Nalco Water, an Ecolab Company, Naperville, IL

Over the past few years, discussions of the impact of cyclical operation have filled the agendas of technical conferences and the pages of trade publications. Even those predisposed to minimizing the impact of cyclical operation — like the National Renewable Energy Laboratory — have conceded that these practices do stress power plant systems.
To address these stresses, many power plants have applied filming corrosion inhibitors to minimize the impact of cyclical operation on their steam systems. Several water treatment companies have developed and applied filming corrosion inhibitors. This paper discusses the application of such an inhibitor at the RWE Generation UK’s Staythorpe Power Station and its impact on corrosion product generation.

IWC 18-32: Decreasing Filterable Iron Levels in an Aircooled Condenser at a Combined Cycle Power Plant
Kevin Brown and Pat Mongoven, US Water Services, Delta, BC, Canada; Pat Mongoven, US Water, St. Michael, MN

The issue of FAC (Flow Accelerated Corrosion) continues to be a leading concern in combined cycle power plants (CCP). The FAC has historically been found on the lower temperature circuits of the Heat Recovery Steam Generator (HRSG), Surface condensers, and inlet area of Air Cooled Condensers (ACC). It has been well documented that there are various factors that affect FAC including velocity, chrome content of steel, temperature, geometry, pH and oxygen content. We will present new information that indicates that pH adjustment with just ammonia is not sufficient to prevent FAC in air cooled condenser (ACC) plants. We wanted to evaluate the effect that additional amine chemistry would provide to lowering the filterable iron in an operating combine cycle plant with an ACC. The level of reduction of iron was monitored with Millipore filters and pressure drop on a full flow cartridge style condensate filter. The chemistries that were evaluated with ammonia include carbohydrazide, cyclohexylamine, morpholine, and monoethanolamine).

The trial showed that specific neutralizing amines had a substantial effect on lowering the amount of iron that would deposit on a filter. We will present the effects of the various amine additions had on the polisher pressure drop. Utilizing this amine combination, polishing full flow filter change outs went from 6 weeks to 6 months. After 3 years on this specific treatment, condensate filter cartridges have been replaced 6 times compared to 27 calculated changes with ammonia treatment alone in the ACC. We would recommend that any combined cycle plant with FAC or high irons evaluate the benefits that neutralizing amines can provide in minimizing iron levels in complex steam/water circuits in these plants.

Consider Attending: W-1, W-2, W-5, W-7, W-10, W-12, W-17


Next Treatment Level – Innovative Water

IWC Rep: Mike Soller, Bowen Engineering, Indianapolis, IN
Session Chair: John Van Gehuchten, P.E., McKim & Creed Inc., Sewickley, PA
Discussion Leader: Peter Meyers, ResinTech, Inc., West Berlin, NJ

Our industry continues to innovate new processes, technology, and overcome obstacles in treating water. Nothing better illustrates this than this wide industry cross section of new approaches to existing challenges. This session includes speakers that will demonstrate the cutting edge work being completed at the Water Technology Development Center for SAGD industry, treated superfund contaminated groundwater, essential improvement to ZLD processes, and using fiber ion exchange material to treat FGD wastewater.

IWC 18-33: Technology Advances and Economic Optimization of Advanced Membrane Brine Concentration and Zero Liquid Discharge
Ellie Albadvi, Ben Sparrow, Megan Low, Anisa Maruschak, Zhongyuan Zhou, and Xin Xiao, Saltworks Technologies Inc., Richmond, BC, Canada

Brine management is essential to industrial and inland desalination where disposal options are limited. As brine volume is reduced, the cost of treating the more concentrated brine increases considerably. This work provides the readers with a technical roadmap, and simple economic model to optimize their total cost of ownership for a brine concentration or zero liquid discharge management system. The typical costs, energy consumption, risks, and tips for optimization are disclosed in reference to membrane systems, evaporators, and crystallizers. In addition, we review pilot data from two novel brine concentration technologies that lower end user costs. The first being a membrane system for pre-concentration, and the second being a thermal evaporator-crystallizer that can be driven by low grade heat.

A new class of ultra-high pressure, spiral wound reverse osmosis (RO) membranes are emerging that can operate at 120 bar. This represents a 50% increase in pressure that allows further volume reduction as osmotic pressure of solutions increase with salinity. While these new spiral wound membranes offer cost advantages over the costlier disk-type RO membranes, the former requires more careful management of scale and fouling. We present pilot test data and economics for these next-generation, ultra-high pressure membranes under various brine concentration conditions, including flux (determines capital cost), scale management requirements, brine concentration results and energy usage (determines operating cost).

We also review a novel thermal evaporation-crystallization process, which applies multiple-effect energy recycling to produce zero liquid discharge solids. This process provides designers with the option to replace traditional multi-step treatment trains with a single plant, that achieves evaporation, crystallization and solids management in one plant. Furthermore, we review the energy recycling system that can operate using low-grade waste heat of approximately 80 to 95 deg C. Knowledge is presented to help designers manage technical risks related to crystallization, avoid extensive pre-treatment, and optimize total cost of ownership. Data from full scale real-world applications is shared, along with tips for final solids management from crystallization.

Readers will develop an improved understanding of the latest technical advancements in brine management and concentration. They will also learn simple formulas and guidelines to optimize cost and manage risk related to brine volume reduction and solids production, regardless of the technology employed.

IWC 18-34: Development of a Fiber-Based Ion Exchange Material for Treatment of FGD and Other Wastewaters
Philip Brandhuber, Ph.D., HDR Engineering, Denver, CO; Tadashi Kamada, Osaka, Japan

The treatment of arsenic and selenium along with other metals concentrated in wastewater from flue gas desulfurization (FGD) is a vexing problem for the electrical power industry. Current treatment approach consists of trains combining chemical, physical and biological processes. Selenium, often in the form of selenate, is particularly difficult to treat, requiring the use of biological process. In addition, the high background levels of sulfates and high total dissolved solids (TDS) of FGD wastewater degrade treatment performance in comparison to less challenging water quality matrices. In summary, while the technology exists to treat FGD wastewater, the technology is not ideal, and there is room for the development of additional other treatment approaches, particularly for the removal of arsenic and selenium.

A fiber based ion exchange material specifically designed for the treatment of arsenic with the potential for selenium removal is currently being developed by the Kaneka Corporation of Osaka Japan. Unlike traditional ion exchange media, in which ion exchange functional groups are bound to a resin bead, this technology incorporates the ion exchangeable groups into a fiber material. When the fiber is loaded into a traditional IX column, the fiber produces minimal headloss and can be operated at greater hydraulic loading rate (HLR) and empty bed contact time (EBCT) than traditional IX resins. In addition, the technology appears to be far less sensitive to competition from sulfate and TDS (ionic strength) than traditional resins. Another potential advantage of the technology is its ability to be fabricated into a mesh or pleated material, creating the potential for deploying the technology in non-column configuration – for example as a cartridge filter with metal removal capabilities.

The purpose of this paper is to review bench-level isotherm and small column tests performed by HDR evaluating the potential performance of this technology in FGD and other waters. The tests completed to date demonstrated low headloss, high arsenic selectivity and capacity, low sensitivity to sulfate competition and good regenerability. The evaluation for selenium removal is continuing with results available in time presentation at the conference. This paper will also discuss potential non-column based uses of the technology in a cartridge filter configuration and future plans for the testing of the product.

IWC 18-35: Canadian Thermal Oil Industry Water Technology Development Center – Purpose, Design and Vision
Brad Sobey and Basil Perdicakis, Suncor Energy Inc., Calgary, AB, Canada; Rodger Bernar, Husky Energy, Calgary, AB, Canada

The C$165MM Water Technology Development Centre located near Fort McMurray, Alberta, Canada will be completed construction by late 2018 and represents a unique opportunity for oil field produced water technology stakeholders to demonstrate or vet their technology at a demonstration scale. Live production fluids at temperature and pressure will be available for delivery to technology skids in a low cost plug and play fashion, without the risk of affecting production operations that can cut trials short or obtaining fluids that are aged and give false results.
Live production fluids at temperature and pressure are available for delivery to technology skids in a low cost plug and play fashion, without the risk of affecting production operations that can cut trials short, or obtaining fluids that are aged and give false results.
While the center is designed to be equipped with a steam generator, emulsion separator, and produced water cooler to conduct some improvement studies, the consortium is also interested in testing new produced water steam generation, evaporation, ion exchange, boiler feedwater treating, silica and hardness removal, membrane, stream analyzers and flowmeters, and oil removal technologies. The intention is to validate the technologies for use in the thermal SAGD industry that currently processes approximately 120,000 USGPM water across 40+ plants and has the potential to double in size over the next 20 years when new low cost technologies are found and validated.

IWC 18-36: Groundwater Remediation System Pilot and Operating Data
Edward Koch, 3M, Charlotte, NC

This paper presents pilot and operating data for a groundwater remediation system installed at an EPA Super Fund site in Southern California. Primary goal of the project was to control dissolved oxygen level in polluted groundwater. Towards that goal, water from the underground aquifer was pumped out and run through a mobile membrane degasification (MDG) skidded system before reinjecting the water back to the underground reservoir. In order to prevent scaling and fouling in the MDG system, an Ultrafiltration (UF) membrane skid was installed prior to the MDG system. Multiple companies with unique competencies were involved in overall system design, fabrication, installation and operation. Before building and installing the full system a smaller scale pilot trial was conducted to (a) verify the effectiveness of the combined UF-MDG system, and (b) study the effect of water quality on the membranes. Data and results from the pilot system as well as the full-scale system will be presented. Importance of critical process parameters and effect of water quality on system performance will be discussed. It is considered highly likely that the success of such an optimized UF-MDG system can be replicated in other Super Fund sites.

Consider Attending: W-1, W-2, W-5, W-10, W-12


Membranes for Mining

IWC Rep: Paul Pigeon, Golder Associates Inc., Lakewood, CO
Session Chair: John Schubert, P.E., HDR, Sarasota, Florida
Discussion Leader: Kashi Banerjee Ph.D., P.E., BCEE, Veolia Water Technologies, Moon Township, PA

The mining industry is experiencing greater attention related to wastewater effluent quality. The increased focus is not just on metals. It is no longer unusual to be regulated for sulfate, total dissolved solids and other soluble constituents, which have in the past not been as much of a concern. New approaches are being developed to meet these challenging situations. The use of membranes in the treatment of mining wastewaters is one area in which new information is rapidly being generated. The papers in this session feature treatment processes in which membranes are a key component. Three of the papers describe the treatment of wastewater from a rare earth mining facility, an acid mine drainage wastewater, and a gold mining wastewater. All utilize reverse osmosis systems as the key process step for separation of soluble constituents. A fourth paper describes a different type of membrane, a permeable reactive barrier that functions in place to treat contaminated water.

IWC 18-37: A New Membrane Based System for Mine Water Discharge Treatment
Rahul Patil and Arun Mittal, Aquatech International LLC, Canonsburg, PA

The mining industry in Latin America is faced with new regulatory requirements that limit the discharge of chlorides, arsenic, cadmium and other constituents of concern into receiving streams such as rivers. To meet these new regulatory standards for a gold mine water discharge, Aquatech have developed a new membrane based treatment approach which maximizes the recovery over 97% of treated water good for disposal.

The process comprises media filtration followed by pre-concentration RO followed by softening in ceramic membrane microfiltration followed by two additional stages of RO to achieve an overall recovery of over 97%. The concentrated brine from the last stage of RO is further concentrated in a small mechanical vapor compression based crystallizer unit. The distillate from the crystallizer unit shall be blended with the RO product water for final discharge to the river while the concentrated brine from the crystallizer shall be converted to dry salt cake in a centrifuge unit for offsite disposal in a landfill. The process is unique in configuration that it optimizes the hydraulic capacity of softening microfiltration step by introducing pre-concentration RO. The pre-concentration RO achieves over 70% recovery thereby reducing the hydraulic capacity of softening microfiltration to only 30% of the original feed flow. The second unique feature of the process is the usage of ceramic microfiltration membrane for chemical softening in lieu of conventional High Density Softening (HDS) clarifier or polymeric membrane based softening. The usage of ceramic membrane allows higher operating flux, much effective cleaning in place compared to polymeric membrane and much longer life of the membrane. The proposed treatment approach minimizes the plant foot print which was a big constraint in this project due to site location and its access. The proposed system is highly modularized that would allow quick installation and start-up.

This paper will discuss the new membrane based system details as well as how it meets new regulatory standards for discharge of the gold mine water.

IWC 18-38: Three Years of Full Scale Water Treatment Plant Operational Experience from Rare Earth Mining
Mohan Badami, Keith Benson, Kashi Banerjee, and Charles Blumenschein, Veolia Water Technologies, Moon Township, PA

A centralized water treatment plant was built in 2012 in a rare earth mining facility in the Southwestern part of the United States to treat well water and water recycled from various systems. The objective of the treatment plant was to produce demineralized water with conductivity < 10 µs/cm for boiler feed and other plant areas. This paper will describe and discuss various treatment steps and will present three years of operational data.

IWC 18-39: MaxH2O DESALTER Technology Treats Calcium Sulfate Saturated Wastewater, a Perfect Solution for Treating Acid Mine Drainage Wastewater
Alex Drak, Roi Zaken Porat, and Tomer Efrat, IDE Technologies, Kadima, Israel; Marco Kerstholt, Royal HaskoningDHV, Umhlanga, South Africa; Gerard Van Houwelingen, Royal HaskoningDHV, Amersfoort, the Netherlands

Acid rock drainage mechanisms involve oxidation of sulfide minerals, leading to highly acidic, metal-rich waters with high sulfate content and high scaling potential. Sulfate is considered a more significant long-term water quality issue for mining operations, and its control levels are based primarily on secondary drinking water recommendations of approximately 500 mg/L. Two methodologies are mainly used to remove sulfate from acid mine water: separation, for example membrane separation; or salt precipitation, for example formation of gypsum.
Conventional membrane separation systems, as a solution for sulfate removal from acid mine wastewater, have several drawbacks that limit the maximum possible system recovery, and even prevent their use in these applications. Conventional membrane systems might be limited when required to handle variable feed quality and variable recoveries, as well as at high supersaturation conditions of calcium sulfate.
A recently developed MaxH2O Desalter technology overcomes these limitations, making it the perfect solution for treating acid mine wastewater. Its many benefits allow this technology to address the different challenges successfully, such as calcium sulfate scaling, and biofouling and organic fouling potentials. The developed system enables operation of a reverse osmosis (RO) system with feed water quality varying from 1,000 mg/L to 70,000 mg/L TDS, and at water recoveries from 25% to 99.9%. The developed system removes sulfate ions by precipitation of calcium sulfate in the integrated salt precipitation unit, while concentrating the wastewater in the RO system. The only limiting factor of the system becomes RO brine osmotic pressure, not supersaturation of calcium sulfate.
This paper presents the recent pilot results obtained with acid mine wastewater. The results show that the system can reach recovery of over 90%, at which the calcium sulfate saturation index theoretically reaches over 1,000%, which leads to immediate calcium sulfate precipitation on the RO membrane. In practice, the calcium sulfate saturation index was maintained in the range of 200% – 400% during operation by its continuous precipitation in the integrated salt precipitation unit. The system operated without the addition of chemicals other than antiscalant, and produced pellets of more than 90% dry solids content, which do not require further sludge dewatering treatment.
These results show the significant advantage of the developed system as a treatment alternative for acid mine wastewater. The developed system saves operational costs by decreasing chemical consumption and the amount of sludge to be discharged, and investment costs by the high recovery that can be achieved.

IWC 18-40: Learnings from Phased Installation of a Permeable Reactive Barrier for Mine Water Treatment
Shannon Brown and John Pugh, Monsanto, Creve Coeur, MO; Molly Prickett, Monsanto, Soda Springs, ID; Matthew Wright, NewFields, Missoula, MT

Weathering oxidation can enable release of oxidized selenium compounds from pyrite and sphalerite laden overburden into surface runoff water and groundwater. The remote nature inherent to mining operations can preclude access to utilities and infrastructure necessary for many water treatment systems. Therefore, passive biotreatment utilizing naturally occurring endemic microbes supported by emplacement of organic matter within an engineered interception and treatment system was selected. Phased installation of this permeable reactive barrier afforded opportunities for optimization.

Consider Attending: W-1, W-2, W-5, W-10, W-12, W-14, W-21


FGD Blowdown – Treatment, Concentration, and Solidification – Oh My!

IWC Rep: Bill Kennedy, Duke Energy Corporation, Charlotte, NC
Session Chair: Kristen Jenkins, P.E., GHD, Duluth, GA
Discussion Leader: Corne Pretorius, Golder Associates, Mississaug, ON, Canada

This session on Flue Gas Desulfurization scrubber wastewater will cover a range of management technologies to comply with current and future discharge regulations. The technologies covered include scrubber optimization to reduce selenate formation, polishing treatment at both pilot scale and full scale to remove particulate selenium, membrane concentration, and the latest in solidification/stabilization research on FGD brines.

IWC 18-41: FGD Absorber Optimization Combined with Physical-Chemical Treatment in Lieu of EPA BAT Technology for FGD Wastewater Treatment
Robert Simm, Stantec, Phoenix, AZ; Josh Pendergrass and Adam Sutherland, Stantec, Nashville, TN

EPA finalized a rule revising the regulations for the steam electric power generating category on September 30, 2015. The revised rule targeted arsenic, mercury, selenium, and nitrate/nitrite in wastewater streams from flue gas desulfurization (FGD) wastewaters amongst others. The BAT identified in the rule was physical-chemical treatment followed by biological treatment. EPA received multiple petitions for review challenging the regulations. The agency later received a letter of petition for administrative reconsideration of the rule, in March and April 2017. The Administrator signed a letter on August 11, 2017 announcing his decision to conduct a rulemaking to potentially revise the new, more stringent BAT effluent limitations and pretreatment standards for existing sources (PSES) in the 2015 rule that apply to bottom ash transport water and flue gas desulfurization (FGD) wastewater. EPA has finalized a rule postponing the earliest compliance dates for the BAT effluent limitations and PSES for bottom ash transport water and FGD wastewater in the 2015 Rule, from November 1, 2018 to November 1, 2020.

The stay in the rule provides an opportunity for power companies to investigate other, potentially more cost-effective approaches, to EPA BAT for FGD wastewater treatment. One such approach involves the control of oxidation air using sulfite concentration in the wet flue gas desulfurization (WFGD) absorber. Sulfite controls provides several benefits. The most important for FGD wastewater treatment include mercury partitioning primarily in the solid phase and selenium species favoring selenite versus selenate formation. FGD wastewater from a retrofitted WFGD absorber can be treated via standard physical-chemical treatment and a clean-up step with zero valent iron (ZVI) or other non-biological system. This is particularly attractive as more power companies consider changing the duty of some of their plants from base load to peak operation.

This paper summarizes bench scale and pilot testing of several case studies to investigate the technical feasibility of the above-noted approach. A recent pilot study on a WFGD absorber suggests approximately 97% of the selenium in the FGD blowdown is present as selenite when an appropriate sulfite control target is selected. Selenite is more amenable to physical-chemical treatment raising the possibility a more cost-effective selenium treatment process can be developed. Preliminary estimates suggest capital cost savings could be as high as 50% relative to EPA BAT for FGW wastewater.

IWC 18-42: Application of Ultrafiltration for FGD Waste and Water Polishing, Comparisons Pilot to Full Scale
Russ Swerdfeger, Evoqua Water Technologies, Colorado Springs, CO; Chuck McCloskey, Evoqua Water Technologies, Schaumburg, IL; Frank Sassaman, Evoqua Water Technologies, Warrendale, PA; Derek Henderson, P.E., Duke Energy, Raleigh, NC

Advanced wastewater process technologies offer power companies a feasible approach to compliance with national and state regulations. This paper presents two similar installations where an ultrafiltration process is being applied after a biological treatment process to remove heavy metals such as mercury, along with TSS for final discharge. We present how the UF process enables the power company to meet and exceed the ELG regulations. Additionally, we present how this technology enables the opportunity to reuse the water in a future scenario.
From April 2017 through July 2017 a pilot scale UF was installed at a facility where a biological process was currently in operation, this paper compares the hydraulic performance and effluent quality of that pilot with the full scale UF system currently being installed at this facility along with a sister facility which uses the same process. The UF system performed quite well from a hydraulic and filtrate/permeate turbidity perspective as noted in the table below:

Parameter Piloted Value
UF Flux 30 gfd vs 16 gfd design
UF Feed Turbidity Average > 6 NTU
UF Filtrate/Permeate Turbidity Average < 0.07 NTU
UF Feed Mercury Average 23.4 ng/L
UF Filtrate Mercury Average 2.2 ng/L

Laboratory analysis of the pilot UF filtrate presents data showing greater than 89% removal of mercury, nearly complete removal of TSS/Turbidity. Other contaminants of concerns such as selenium and nitrogen were removed to the desired level within the biological process. Our paper presents a detailed analysis of the UF pilot and the two full scale UF systems which are presently being installed. We will demonstrate in this paper that UF is a viable solution which enables power companies to ensure regulatory compliance for current and proposed regulations but that UF provides an enabling technology for future reuse options to the power companies.

IWC 18-43: A Scale-Resistant, Membrane-Based Solution for the Treatment of FGD Wastewater to Meet ELG
Jon Liberzon, Jonathan Chen, and Tzu Lung Lin, Tomorrow Water (BKT), Anaheim, CA; Arnab Hanra, Jaeho Ho, and Chunwoo Lee, SafBon Water Technology, Tampa, FL

Flue gas desulphurization (FGD) wastewater is a byproduct of pollution control processes at coal-fired power plants. The EPA’s effluent limitation guidelines (ELG) mandate treatment of this wastewater to meet selenium (Se), arsenic (As), mercury (Hg) and nitrate/nitrite (NOx) limits prior to discharge. Other compounds or total dissolved solids (TDS) may also be regulated by state-issued NPDES permits. FGD wastewater contains concentrated scale-forming compounds, which cause membrane fouling and make conventional membrane treatment unattractive. To solve this problem, we deployed a new anti-scaling membrane platform to treat FGD wastewater at a >2,000 MW power plant. Trade-named FMX, the system uses rotating blades to create hydraulic vortices on the membrane surface, preventing fouling and scaling. Over 5 months, the industrial-scale demonstration treated 5,000 gal/d using two nanofiltration membranes to verify full-scale performance. Using a loose NF membrane, average removal rates for target pollutants were 80%, 94%, 63% and 40% for As, Hg, Se and NOx, respectively, at an average flux of 61 gal/ft2d (108 LMH) with negligible scaling/fouling observed. Using a tighter NF membrane, removal rates increased to 92%, 97%, 82% and 58% for these constituents, but were offset by a reduction in flux of 68%. FMX effluent was able to meet the US EPA’s BAT and BADCT treatment standards for FGD discharge (2015 rule 40 CFR Part 423) but was not able to guarantee adherence to Se and NOx limits without downstream membrane processes. Two post-polishing configurations, FMX – NF – RO and FMX – RO, were simulated to meet the FGD wastewater discharge ELG. The designed water recovery rate for both process configurations was 54.4%. Results showed that an FMX – NF – RO configuration can significantly reduce the number of pressure vessels and membrane modules required and reduce the size of the evaporator needed. These results suggest that FMX, in conjunction with downstream membrane processes, represents an attractive option for meeting ELG limits in FGD wastewater while also reducing TDS and other compounds which may appear on NPDES permits.

Note: Data from an ongoing demonstration at another power plant will also be presented in the final paper. That study assesses alternative process configurations.

IWC 18-44: Wastewater and Brine Management using Encapsulation: Laboratory and Pilot Testing Results, New Findings, and Testing Recommendations
Kirk Ellison, EPRI, Charlotte, NC

As investigations continue into volume reduction approaches for wastewater management, environmentally responsible solutions are needed to address the final disposal of the resulting concentrated wastewater or brine. Encapsulation, as defined in this paper, involves accurately combining wastewaters with coal combustion byproducts, including fly ash, bottom ash, and gypsum, and additives (e.g. quicklime, cement, aluminates). The overall goal of encapsulation is to create a low permeability material upon landfill deposition that sequesters and inhibits long term re-release of constituents of concern to the environment. This paper discusses the key focus areas of brine encapsulation research and presents results from ongoing studies. Additionally, recommendations and lessons learned for conducting encapsulation testing are presented based on experience gained through bench and pilot testing. Finally, the relationships between encapsulation and process technologies such as, such as paste, are explored.

Consider Attending: W-1, W-2, W-4, W-5, W-10, W-12