### MEMORANDUM

TO: Public Record for the Effluent Guidelines Program Plan 2009/2010

FROM: TJ Finseth, ERG

DATE: 10 February 2009

SUBJECT: Notes from EPA Meeting on June 5, 2008 with HPD/Veolia Water Solutions and Technologies to Discuss F GD Wastewater Treatment

EPA and ERG participated in a meeting with HPD/Veolia Water Solutions and Technologies (VWS) on June 5, 2008 to discuss treatment tech nologies for FGD wastew aters. The following people participated in the meeting:

HPD/VWS Bill Shaw Jeff Brosdal

EPA Ron Jordan Josh Hall

ERG Deb Bartram TJ Finseth (via phone)

This memorandum summarizes the meeting disc ussion points. The presentation that HPD presented during the meeting is provided as an attachment to the memorandum.

EPA Study Background

 EPA explained that they are reviewing the Effluent Guidelines for the Steam Electric Power Generating Industry to determ ine if revisions to the guidelines are warranted. EPA stated that they have b een studying the indust ry for several years now, but had a broad focus at the beginning of the study and now they are focusing on FGD, ash sluice, and coal pile runoff wastewaters.

Company Overview

 HPD explained that they have a parent company, Veolia Environnement, which has the following four company sectors:

— Veolia Water;

— Veolia Environmental Services;Memorandum November 6, 2008 Page 2

— Veolia Energy; and

— Veolia Transportation.

 Part of the Veolia Water sector is Veolia Water Solutions and Technologies (VWS). HPD explained that this is the technological division of Veolia Water and focuses on municipal a nd industrial customers.

 HPD is a subsidiary of VWS and fo cuses only on industrial customers.

 HPD stated that they provide innovative process solutions utilizing evaporation and crystallization technologies, and they are the largest evaporation/ crystallization company in the world.

 HPD also provides ceramic membrane technology (CeraMem ®) through their HPD Membrane Technology Center, located in Waltham MA.

 HPD has several offices around the worl d and has approximately 150 employees.

 HPD has experience in multiple industrial sectors, including chemical processing, power generation, oil and gas, et hanol/biofuel, and pulp & paper.

 HPD stated that they are capable of provi ding complete turnkey solutions to their customers, including both designing and building systems.

FGD Wastewater Treatment Options

 HPD has focused its efforts on FGD wastew ater treatment associated with wet limestone forced oxidation systems, which, according to HPD, accounts for 80 to 90 percent of the wet FGD scrubbers.

 [CBI information has been removed from this document.]

 HPD provides evaporation and crystallizat ion technologies for the treatment of FGD wastewater, which achieve s zero-liquid discharge.

 HPD stated that the other treatment te chnologies currently available to power plants include physical/chemical/biologica l treatment which produces a discharge to surface waters.

 The physical/chemical treatment system s are capable of removing suspended solids and heavy metals. The biological systems are capable of removing BOD, nitrogen, and some heavy me tals. In addition, the biol ogical systems typically require a solids removal step to remo ve the suspended solids prior to the biological treatment step.

 The physical/chemical/biological treatmen t systems do not remove chlorides or dissolved solids from the wastewater. In addition, they do not recover clean water for reuse at the plant. HPD also stated these systems typically have a large footprint, and a high chemical demand.

 HPD stated that some power plants are af raid of evaporation technologies for the treatment of FGD wastewater because th e industry has the perception that it is expensive, difficult to op erate, and challenging.

History of Evaporation at Power Plants

 According to HPD, falling-film evaporators (brine concentrators) have been used at power plants for the treatment of c ooling tower blowdown since the 1970’s. The brine concentrator, which is discu ssed in more detail later in the notes, produces a quality distillate stream that can be reused by the plant and a concentrated brine stream. The use of a brine concentrator followed by aMemorandum November 6, 2008 Page 3

crystallizer or a spray dryer to evaporate the remaining water in the concentrated brine stream results in zero liquid discharge (ZLD).

 HPD stated that there are 50 to 75 brin e concentrators treating cooling tower blowdown from power plants in the U.S. HPD stated that most of these applications are in the West (i.e., along the Colorado River, in California, or the southwest). HPD stated that they beli eve that all new power plants built in California will be permitted as zero liquid discharge and will have to eliminate direct discharge of cooling tower blowdown.

 HPD stated that plants in those areas ar e using evaporators because they need to conserve water as well as prevent sa lt water discharges to the rivers.

 HPD stated that reverse osmosis could also be used to treat cooling tower blowdown, but it is not a ZLD system a nd therefore would have a discharge.

 HPD stated that the ZLD systems treati ng cooling tower blowdown are capable of achieving high concentration factors. The concentration factor of the system represents the factor by which the str eam is concentrated, meaning that a concentration factor of four will produce a concentrated brine stream where the pollutant concentrations are four times higher than the influent because there is four time less (75% less) water in the con centrated brine stream. HPD stated that the higher the concentration factor, the mo re water that can be recovered. HPD estimated that approximatel y 95% of the cooling tower blowdown water can be recovered as quality disti llate, which is equal to a concentration factor of 20.

FGD Wastewater Treatment Issues

 HPD stated that treating F GD wastewater with a ZLD system is more difficult than treating cooling tower blowdown b ecause of the chemistry of the FGD wastewater. HPD stated th at FGD wastewater contains higher levels of TDS, chlorides, suspended solids, heavy me tals, boron, ammonia, and COD. In addition, the primary salt in cooling to wer blowdown is sodium, compared to calcium and magnesium in FGD wastew ater. Finally, FGD wastewater is saturated in gypsum.

 The differing wastewater chemistries be tween the FGD wastewater and cooling tower blowdown have the following impacts on the design for treating FGD
wastewater:

— High levels of TDS (20,000 - 40,000 mg/L ): restricts the concentration factor achieved by the brine concentrat or. In addition, it prevents the use of reverse osmosis because the wastew ater is already above the osmotic pressure limits.

— High levels of chlorides (10,000 – 30,000 mg /L): has the pote ntial to cause pitting or stress cracking in the evap orator; therefore, noble materials of construction are required.

— High levels of suspended solids: has the potential to bui ld up and clog the system; therefore, pretreatment is re quired to remove the solids. [CBI information has been removed from this document.]

— Gypsum at saturated levels: will precipitate out of solution as water is evaporated, which would cause scal ing on the evaporator equipment; therefore, a seeded slurry of calcium su lfate crystals needs to be fed to the system to prevent scaling.Memorandum November 6, 2008 Page 4

— High levels of heavy metals, boron, ammonia, and COD: These chemicals can interfere with the seeded slurry, as well as contaminate the distillate produced.

— Calcium and magnesium salts: These salts are aggressive acid salts which require noble materials of constructio n. In addition, these salts have a high boiling point rise as they beco me more concentrated; therefore, additional power is required to achieve these higher temperatures.

Brine Concentrator System Design for FGD Wastewater

 HPD uses falling-film evaporators, also known as a brine concentrator, in the design of the ZLD systems because they ha ve a high heat transfer coefficient, which requires less surface area to achiev e the same heat transfer. Because less surface area is needed, the equipment is smaller. Additionally, brine concentrators allow a large amount of surface area to be packed efficiently in a small space, making a smaller footprint for the system.

 In the brine concentrator, the FGD wastewat er is pumped to the top of the brine concentrator and a pair of distribution pl ates disperse the li quid evenly among the heat transfer tubes. The heat transfer tubes are approximately two inches in diameter and are thin-walled to improve heat transfer. The tubes are typically about 50 feet long. Because the tubes are thin, they are vulner able to pitting and cracking. HPD usually constructs the tube s out of titanium due to its strength, good heat transfer properties, and corrosion resistance. HPD stated that titanium cannot be used in waste streams with hi gh fluoride concentrations. Waste streams with high concentrations of fluoride can be addressed by substituting titanium with inconel or similar alloys.

 As the liquid enters the heat transfer tube s, it creates a film along the inside walls of the tube. This film allows for better heat transfer to occur. HPD prevents the liquid from flooding the tubes by controlling the flow rate within the tubes and the level of the combined feed and conc entrate at the bottom of the brine
concentrator.

 As the liquid flows down the heat tran sfer tubes, steam condenses along the outside of the heat transfer tubes. The st eam transfers its heat to the liquid inside the tubes and some of the water is ther eby evaporated to steam and continues flowing downward in the tubes along with th e remaining liquid. In addition, the steam on the outside of the tubes condenses and falls to the bottom of the brine concentrator where it is collected a nd recovered as a qua lity distillate.

 When the vaporized water reaches the botto m of the brine con centrator, it exits the heat transfer tubes and begins fl owing upward, thereby separating from the liquid. This vapor then passes through a mist eliminator, which removes any entrained liquid from the vapor. The mi st eliminator allows the vapor to pass through, but the water is entrapped and fa lls back downward in to the bottom of the brine concentrator.

 The vapor is then sent to a compressor to compress the vapor, which raises its saturation temperature. This compressed va por is used as the steam in the brine concentrator, and eventually becomes the quality distillate. This process is known as mechanical vapor compression.Memorandum November 6, 2008 Page 5

 HPD uses the mechanical vapor compre ssion system in the design of the ZLD systems because it is energy efficient. Because the heat of vaporization from the water vapor is recovered and recycled by vaporizing additional liquid, the only input to the system is th e electrical energy used to run the compressor. HPD stated that the energy input to a mechanic al vapor compression evaporator is 30 to 60 BTU/lb distillate, compared to 1,000 BTU/lb distillate for a steam-driven evaporator.

 HPD stated that steam is needed in the mechanical vapor compression system during the cold start up to begin the process.

 HPD stated that they also use seeded sl urry in the brine concentrators that are treating FGD wastewater to control scale fo rmation. The seeded slurry consists of adding calcium sulfate seed crysta ls to the circulated liquid.

 The low solubility salts will precipitate out of the circulated liquid as it becomes more concentrated. The seeded slurry causes these salts to preferentially precipitate out onto the seed crystals instea d of precipitating onto the heat transfer tube walls.

 HPD uses a hydroclone to recycle the seeded slurry within system. The concentrated stream leaving the brine con centrator is sent to a hydroclone where the solids (seed crystals) are separated from the liquid. The seed crystals are recycled back to the brine concentrator, and the liquid continues to the next step in the process.

 HPD stated that there are some constituents within the FGD wastewater that can interfere with the seeded slurry; howev er, HPD stated that it was proprietary information. HPD stated that this was the reason that the AES Milliken (Cayuga) ZLD system did not operate properly.

 In addition to the brine concentrator, HPD typically has a feed tank, a feed preheater, and a deaerator that operate within the system. The feed tank is used to add an acid to the waste stream to co nvert the calcium carbonate to carbon dioxide and add an anti-scalan t. The feed preheater uses the distillate stream to heat the feed to its saturation temperature. The deaerator uses steam vented from the brine concentrator to strip the noncondensables (e.g., carbon dioxide, oxygen) from the feed stream. [CBI information has been removed from this document.]

 HPD stated that the brine concentrator does require cleaning over time. HPD stated that the brine concentrator can be chemically cleaned, or the tubes can be hydroblasted to remove build up. HPD stated that the system is usually cleaned as part of a plant shutdown, one to two times per year.

 HPD stated that the brine concentrator is typically designed for a 30-year lifetime.

Options for Treating FGD Wastewater

 HPD stated that there are currently two different options available for treating FGD wastewater with an ev aporator system. The firs t is to evaporate the FGD wastewater directly (Opti on 1). The second is to ev aporate the FGD wastewater following a softening pretre atment step (Option 2).

 For Option 1, the FGD wastewater would need to undergo a solids removal step prior to the brine concentrator. The wastewater would then go to the brine concentrator, which would operate sim ilar to the one described previously.Memorandum November 6, 2008 Page 6

 HPD stated that the brine concentrator for an Option 1 system can typically concentrate the stream 4 to 5 times, whic h would recover 75 to 80 percent of the water. HPD stated that the system is limited by the TDS and the boiling point rise of the calcium salt. As the calcium salt becomes more concentrated in the water, the boiling point for the solution rises, wh ich requires more power to evaporate the liquid.

 The Option 1 system is based on calcium and magnesium chemistry, which means that a crystallizer cannot be used for the final drying stage because calcium chloride won’t crystallize. Therefore, the Option 1 system will typically use a spray dryer for final drying. In the spray dryer, the liquid is sprayed downward into a large chamber and hot air (created from burni ng a fuel, typically natural gas) evaporates the liquid and the remaini ng salt particulates are collected at the bottom of the chamber.

 The dry salt generated from this process is hygroscopic, which means that it will readily take up and retain moisture. To pr event issues with ha ndling the salt, it is typically bagged immediat ely after it is generated and then disposed.

 [CBI information has been removed from this document.]

 For Option 2, the FGD wastewater is pretre ated with lime and soda ash to remove the solids in the wastewater and to co nvert the chemistry in the water from calcium and magnesium based to sodium based.

 [CBI information has been removed from this document.]

 The Option 2 system uses the same design fo r the brine concentrator system as the Option 1 system. The brine concentrator will achieve a similar concentration factor as achieved for Option 1 (4 to 5 tim es); however, because the wastewater is based on sodium chemistry, the boiling point rise will be less, which will require less energy.

 The Option 2 system has the capability to use a crystallizer for the final drying stage because of the sodium-based chemistry. The crystallizer will generate a sodium chloride by-product and the solids will be landfilled.

 HPD stated that Option 2 typically looks better economically because of the reduced power consumption from the use of a crystallizer vers us a spray dryer.

HPD’s New Option for Treating FGD Wastewater

 HPD recently developed a new evaporati on technology to treat FGD wastewater.

 HPD stated that the new technology is a single stage system that can treat the FGD wastewater directly.

 HPD stated that no pretreatment is require d for the system. The only input to the system, other than the FGD wastewater , is the electrical energy. The solid product is produced in the evaporator and there is no need for crystallizer, spray dryer, or further processing. The output fr om the system is the recovered quality distillate and a stable solid s product that requires dewa tering from a centrifuge or filter.

 HPD stated that the system is commercia lly ready, but they are waiting for the patent approval before it is made publicly available.

 HPD stated that the capital cost for the system is approximately 25% less than a physical/chemical system. The O&M costs are expected to be comparable to a physical/chemical system, but with 60 pe rcent reduction in system footprint.Memorandum November 6, 2008 Page 7

The Future for ZLD Systems Treating FGD Wastewater

 HPD stated that the U.S. is installing approximately 40 wet scrubbers per year. HPD stated that China is adding sc rubbers at an even faster rate.

 HPD stated that with the Option 1 and Option 2 ZLD systems available, probably only 10% of the new scrubbers will use a ZLD technology for th e treatment of the
wastewater.

 HPD stated that ZLD systems are typically easier to operate at larger power plants because there is less swing in the plant’s loading.

 HPD stated that the cost and the unfam iliarity of the ZLD system are the two biggest reasons why plants aren’t installing ZLD systems to treat FGD wastewater. HPD stated that there is no reason for the plants to spend the extra money on the ZLD system at this time.

 [CBI information has been removed from this document.]

 A ZLD system provided by Veolia/HPD has b een installed at Monfalcone in Italy At the time of the June 5 meeting, the ZLD system was in the process of starting up. The evaporators were running on wate r but were not expected to receive scrubber purge until early July. This system uses softening, followed by evaporation, followed by a crystallizer.

ZLD Technology for IGCC plants

 There are four IGCC plants operating in th e world currently. Three of the plants use ZLD systems to treat the gasifier wastewater.

 HPD stated that the IGCC plants have a clar ifier right after the gasifier to remove the solids from the gasifier water. HPD stated that the brine concentrator is located after the clarifier.

 HPD stated that the water characteristic s of the IGCC wastewater are different than the FGD wastewater, especially the chlorides concentrations. [CBI information has been removed from this document.]

Additional Contacts

 HPD stated that Larry Gunari is knowl edgeable about the power industry and treatment options for various waste streams, as well as treatment options for reuse of waste streams. Larry’s phone number is (937) 238-3965.

 HPD stated that Terkel Christensen, Kr uger A/S is a contact for the MetClean® system. Terkel’s phone number is +45-3957-2474 and his e-mail is tcc@kruger.dk.