## The Science of Marcellus Shale
January 29, 2010 Hosted by Lycoming College in Williamsport, PA Sponsors: Susquehanna River Heartland Co alition for Environmental Studies and Foundation for Pennsylvania’s Water Sheds and Rivers.



### Marcellus Hydrofracture Flowba ck and Production Wastewater Treatment, Recycle, a nd Disposal Technologies

Timothy Keister, CWT ProChemTech International, Inc. Brockway, PA2 Introduction: Development of the Marcellus gas play in the Northeast; primarily Pennsylvania, New York, and West Virginia , will generate an estimated 7,000 million gallons per year (mgy) of hydrofracture flow back and production wastewater that will have to be managed. This wastewater, as shown by the followi ng “typical” analysis,

contains substantial amounts of toxic barium as well as large amounts of many other elements and compounds.

Parameter “Typical” Analysis – NE PA pH 6.0 aluminum, mg/l 3.0

barium, mg/l 6,500 calcium, mg/l 18,000 chloride, mg/l 116,900

iron, mg/l 60 lithium, mg/l 150 magnesium, mg/l 1,300 manganese, mg/l 5.0

sodium, mg/l 48,000 strontium, mg/l 4,000 sulfate, mg/l SO 4 130 dissolved solids, mg/l 195,000 total hardness, mg/l CaCO 3 54,500 total suspended solids, mg/l 1,200

Three methods for management of this wa stewater are considered viable today, pretreatment prior to additional treatment and discharge to stream via publicly owned treatment works (POTW), evaporation i (with and without subse quent water recovery), and various chemical precipitation processes ii with either recycle of the treated water or subsequent evaporation.

Pretreat and Discharge Via POTW The Brockway Area Sewer Authority (BAS A) operates a new extended aeration, oxidation ditch activated sludge POTW trea ting a mix of industrial and domestic wastewater from Brockway and two nearby townships. BASA was approached by a gas well service company in 2006 as to accepti ng brine wastewaters for treatment and discharge. A treatment contract was agr eed upon; following which BASA obtained an NPDES permit amendment from the PADEP on April 17, 2007, for treatment of up to 14,000 gpd (9.7 gpm) through the BASA plant. Th e service company then constructed a pretreatment system consisting of an oil/solid s separator and aerated equalization tank at the BASA plant, with the first wast ewater accepted in early November, 2008.

Several effects have been noted on treatment plant operation due to introduction of the

brine water.3 Development of a floating sludge layer on the final clarifiers has limited the brine flow rate to no more than 8 gpm of brine water at an average POTW flow of 0.5 mgd. This floating material is believed to result from combination of calcium in the brine water with soaps and fats in the plant influent.

A substantial increase in sludge generation has also been noted. On analysis, the sludge

was found to have a barium content of 1,490 mg/kg, which was of some concern as barium is a USEPA toxic (hazardous) metal. Fortunately, a subsequent hazardous waste determination (TCLIP) on the sludge gave a bari um extract value of just 1.56 mg/l, well below the 100 mg/l level for classification as a hazardous waste. It has been calculated that at our average brine treatment rate, an extra 780 lb/day of barium sludge is being produced.

Mass balance calculations on th e plant effluent and input from the brine water also

demonstrated that a substantial amount of calcium was being removed by the plant processes. Typically, about 240 lb/day of a dditional calcium sludge is being produced by

treatment of the brine water.

The dissolved solids in the plant effluent, le ss than 400 mg/l prior to acceptance of brine, typically are in the area of 2500 to 3000 mg/l when brine water is being treated. The following table compares some typical brine and BASA effl uent results.

Parameter – mg/l Composite Brine BASA Effluent

barium 690 8.0 calcium 23,200 240

iron 160 0.06 magnesium 2,240 27.6 manganese 10.1 0.41

strontium 732 8.1 dissolved solids 224,300 3,005

From these results, it is evident that the plan t process also removes significant amounts of iron, magnesium, manganese, and strontium from the brine water. The amount of brine

water that can be treated via a POTW is restricted by plan t operational problems caused by various brine constituents and water quality criteria limits for the receiving stream.

Evaporation While evaporation is a viable method to dis pose of this wastewater, its use presents several problems that have not been addre ssed by the various process promoters.

Evaporation of untreated wastewater will produce a substantia l amount of residual

soluble salt solids that will be considered a hazardous waste on testing with the required USEPA TCLP method. For example, using our typical wastewater above, evaporation would produce a mixture of soluble chloride salts containing 3.33% barium by weight. Running the TCLP test on this mixture woul d result in a leachate containing 1,665 mg/l of barium, the USEPA limit for being consid ered a hazardous waste is 100 mg/l barium.4 Accordingly, the residual salt mixture produced by evaporation of the untreated

wastewater would be considered to be a hazardous waste and have to be disposed of as such, a costly proposition.

This problem has been recognized and is a ddressed by treating the wastewater prior to evaporation by chemical precip itation of the barium. Removal of the toxic barium as an insoluble, non-hazardous sludge results in a treated wastewat er that can be evaporated without producing a hazardous waste.

Another, generally unrecognized, problem with evaporation is the amount and chemical composition of the residual salts produced and how they can be managed. Using our typical wastewater, treated for barium re moval, evaporation of 250,000 gpd will produce 397,823 lb/day (approximately 200 tons/day) of a mi xture of residual salts. Some of these salts, such as calcium chloride, are deliquescen t (absorbing moisture fr om the air); all are very soluble in water as shown in the following table iii :

Chemical Solubility Chemical Solubility barium chloride 37.5 g/100 ml calcium chloride 74.5 g/100 ml lithium chloride 63.7 g/100 ml magnesium chloride 54.25 g/100 ml sodium chloride 35.7 g/100 ml strontium chloride 53.8 g/100 ml

Based on the solubility of these salts, disposal of the residual salt mixture from treated wastewater evaporation in a la ndfill of any kind would appear to be impractical due to their ready formation of liquid salt solutions on contact with any water or moisture.

Use of the residual salts, in either solid fo rm or as a brine solution, for roadway deicing has been proposed. This would appear to be ruled out by th e recent PADEP proposal iv to regulate strontium in aqueous effluent at 10 mg/l.

Due to the deliquescent properties of calcium chloride, and its presence in large amounts (26% in our typical treated wast ewater residual salt), use of the residual salt in any solid form would in practice be impossible due it its tendency to rapidly form a liquid solution in higher humidity conditions a nd cake the rest of the time.

To address these concerns with disposal of the solids produced by evaporation, the process will have to be proceeded by chem ical precipitation to remove the calcium, magnesium, and strontium from the brine wa ter, effectively conve rting the brine to

sodium chloride brine. Sodium chloride br ine can then be concentrated for use as a deicing solution or evaporated to make salt for industrial use.

Chemical Precipitation Processes Current practice for treatment of brine waters is to ad just the pH using calcium hydroxide, clarify the water to remove any h eavy metal precipitates, and then discharge the treated water to stream. This process is used to treat and discharge an estimated 550 mgy by the several brine water treatment plan ts currently operating in the state.5 New facilities will not be able to use this treat and discharge process due to the new dissolved solids, barium, and strontium effluent re quirements in pending state regulations.

Treatment of high barium and strontium content brine waters, most Marcellus wastewaters, will not be possible due to th e high solubilities, 31,165 mg/l as barium, and 6,123 mg/l as strontium, of the barium a nd strontium hydroxides produced by calcium hydroxide pH adjustment given the 10 mg/l effl uent limits for barium and strontium in the pending state regulations.

Considering recycle of the brine water fo llowing treatment, the calcium hydroxide precipitation process can be modified to rem ove both barium and strontium as insoluble precipitates by adding su lfate ion prior to the calcium hydr oxide addition. A number of

sources v have been utilized to determine the foll owing parameters for successful recycle

of treated brine water as hydrofracture makeup water.

Recycle Water Specifications maximum scale formers – 2,50 0 mg/l as calcium carbonate

maximum dissolved solids – 50 ,000 mg/l maximum iron – 3.5 mg/l maximum calcium – 250 mg/l pH range – 6.5 to 7.5

Unfortunately, use of calcium hydroxide as the treatment reagent, even with addition of sulfate ion to remove barium and strontium, will result in finished water that far exceeds

the calcium and total hardness values for su ccessful recycle. Even with addition of

sufficient sulfate ion to react with all the ca lcium present in our typical brine water to produce a calcium sulfate precipitate, the calcium level in the finished water would be in the area of 2,100 mg/l with the scale former level exceeding 5,000 mg/l. We note that one proposed treatment and recycle facility vi does not give a specification for calcium in their finished water, likely due to the use of a sulfate/calcium hydroxide treatment process.

Sequential Precipitation Process (SPP) The SPP was developed to address the problem s presented by treatment of Marcellus wastewater for recycle or final disposal by evaporation. The process first removes barium

from the wastewater as barium sulfate sl udge via precipitation unde r controlled pH and

ORP conditions.

Following barium removal, the remaining scale formers; calcium, iron, magnesium, manganese, and strontium are precipitated as carbonates a nd hydroxides in two separate precipitation steps using sodium carbonate and sodium hydroxide additions. After clarification, the pH of the fi nished water is adjusted to meet recycle specifications by

addition of carbon dioxide. As the chemical composition of Marc ellus flowback and production wastewaters varies dependent upon the well location and elapsed time since the fracture was completed, we ha ve undertaken an extensive seri es of treatability tests on a wide range of wastewaters to determine the widespread applicab ility of the SPP. The following test results are typical:6 Marcellus flowback water sample – lo w dissolved solids, Hydrofracture 2

Parameter untreated treated barium mg/l 2,300 <0.1 calcium mg/l 5,140 6.0

iron mg/l 11.2 0.04 magnesium mg/l 438 1.09 manganese mg/l 1.9 <0.04

strontium mg/l 1,390 45.8 total hardness mg/l as CaCO3 17,941 71.8

total dissolved solids mg/l 69,640 57,660

Marcellus flowback water sample – mode rate dissolved solids, Hydrofracture 1

Parameter untreated treated barium mg/l 3,310 <0.1 calcium mg/l 14,100 7.25

iron mg/l 52.5 1.7 magnesium mg/l 938 1.6 manganese mg/l 5.17 <0.04

strontium mg/l 6,830 10.4 total hardness mg/l as CaCO 3 49,416 39.6

total dissolved solids mg/l 175,268 59,850

Marcellus flowback water sample – hi gh dissolved solids, Hydrofracture 4

Parameter untreated treated barium mg/l 4,300 < 0.1 calcium mg/l 31,300 2.15

iron mg/l 134.1 1.60 magnesium mg/l 1,630 1.10 manganese mg/l 7.0 0.14

strontium mg/l 2,000 1.60 total hardness mg/l as CaCO 3 90,633 14.9

total dissolved solids mg/l 248,428 150,520

The amounts of sludge produced by any precipit ation process used to treat a Marcellus wastewater will be large. Using our typi cal brine water concentration of 6,500 mg/l barium, treatment of 100,000 gallons/day of this water would produce about 9,200 lb/day of dry barium sulfate sludge. We believe that this material can be further processed and reused as a weighting agent for drilling mud. The amounts estimated to be produced by

treatment of Marcellus wastew aters when the play is fu lly developed, 250,000 tons/yr, would approximate 10% of the annual use of ba rium sulfate used in drilling mud in the United States. Of interest, the majority of th e barium sulfate used is imported and acid mine drainage, common in some areas of the Marcellus gas play, can be used as a low

cost sulfate ion source in the SPP.7 The second mixed sludge produced by the SPP is almost insoluble as shown in the following table vii :

Chemical compound solubility as com pound, mg/l solubility as element, mg/l

calcium carbonate 140 56

iron hydroxide 7.2 3.75 magnesium hydroxide 11.7 4.9 manganese hydroxide 0.35 0.22

strontium carbonate 10.9 6.3

Using our typical brine water concen trations of 18,000 mg/l calcium, 1,300 mg/l magnesium, and 4,000 mg/l strontium; treatment of 100,000 gallons of this water would produce about 45,700 lb/day of dry mixed carbonate/hydroxide sludge.

Reuse of this sludge as a ra w material for production of cement has been proposed. Other potential uses would be as an acid soil neutralization reagent, a phosphate removal reagent in POTW, or as a replacement for limestone in fluidized bed boilers.

In the event that reuse of e ither, or both, of the sludges produced by the SPP cannot be accomplished, they can be disposed of in an approved landfill as they have been TCLIP

tested and found to be non-hazardous.

For recycle, the SPP treated wastewater will normally have to be blended with a low dissolved solids water, treated acid mine draina ge is ideal, to reduce the dissolved solids value to below the maximum value. Recycle will be a viable option for management of hydrofracture flowback and production wastewat ers as long as the need for hydrofracture makeup water is substantially greater, a factor of four, th an the amounts of wastewater produced. This will likely hold true in the Mar cellus gas play for a period of 5 to 10 years

from 2010.

At that point in time when wastewater production exceeds demand for hydrofracture makedown water, evaporation of SPP treate d wastewater will be required. Unlike the current proposed evaporation methods, eva poration of SPP treated wastewater will produce an almost pure sodium chloride resi dual salt, which has several potential uses such as softener regeneration, road deicing, and raw material for ch emical manufacture.

In addition to the high temper ature thermal evaporation proc esses currently marketed, the SPP patent application disclose s a low temperature method wh ich utilizes low grade heat, such as condenser water at a power plant, for evaporation of SPP tr eated wastewater. As an example, a low temperature evaporator designed to evaporate 3,750 gpd of treated wastewater would require a c ondenser water flow of 150 gpm at 105 F, returning to the power plant cooling system at 85 F and using 7 hp of electrical power for unit operation.

With reuse of produced barium sulfate, inso luble mixed sludge, short term recycle of the treated wastewater, and reus e of the residual salt produced by evaporation, the SPP appears to be the best method for manageme nt of Marcellus gas play wastewaters.8 i STW Resources, Inc., “GE Thermal Evaporat ion Technology”; Heartland Technology Partners LLC, LM_HT Wastewater Concentr ator”, and several others.

ii USPTO Application 61/199,588, “Treatment of Gas Well Hydrofracture Wastewaters”, filed 11/19/2008, ProChemTech International, Inc.

iii CRC Handbook of Chemistry and Physics, 57 th Edition, Physical Constants of Inorganic Compounds

iv

PAEQB, proposed rulemaking, 25 PA code, Ch apter 95, PA Bulletin, Volume 39.

v personnel communications, L. Case, Halliburton to T. Keister, ProChemTech and Proceedings and Minutes of the Hydraulic Fracturing Expert Panel , XTO Facilities, Fort Worth, TX, 09/26/07

vi TerrAqua Resource Management, WEB page memo dated 01/11/10

vii American Chemical Society “Solubilities of Inorganic and Metal Organic compounds”, Fourth edition, 1958

Speaker Biography Timothy Keister, CWT, holds a B.Sc. in Ce ramic Science from Penn State and is the

Chief Chemist/President at ProChemTech Intern ational, Inc. He is an Association of Water Technologists Certified Wa ter Technologist, Fellow of the American Institute of Chemists, Senior Member of the American In stitute of Chemical Engineers, and member of the American Society of Heating, Refr igeration, and Air Conditioning Engineers, American Chemical Society, and the Water Environment Federation. His career in the environmental/technical water field began at Brockway Glass Company in 1973, where he was responsible for management of water and wastewater activities at 38 manufacturing plants acro ss the country. In 1987 he founded ProChemTech, which specializes in innovative water and wastew ater management technology with emphasis on treatment/recycle and zero discharge projec ts. Some spare time is also devoted to activities as Chairman of the Brockway Area Sewerage Authority a nd Technical Director of the Toby Creek Watershed Association.

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