430F98082
United States
Environmental Protection Agency
Air and Radiation
6202J
Draft
October 1997
oEPA
EPA Coalbed Methane Outreach Program Technical Options Series
COAL MINE METHANE USE IN BRINE WATER TREATMENT
Coal Mine Methane-Fueled Evaporator at Morcinek Mine, Poland
(Photo Courtesy of Aquatech Services, Incorporated)
AN INTEGRATED APPROACH TO DISPOSAL OF PRODUCED BRINES
+ Wastewater treatment process uses coal mine methane as fuel
+ Can be an economically viable alternative to other water management
methods
* Appropriate for coal mines and coalbed methane fields producing large
volumes of saline water
* Produces fresh water suitable for domestic, industry, or agriculture usage
+ Can use medium quality gas (as low as 50 percent methane)
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The use of coal mine
methane enhances
brine water treatment
economics while
reducing emissions of
methane to the
atmosphere
Desalination plants
typically have large
fuel requirements, and
coal mine methane is
a clean, low-cost fuel
Desalination
processes (unlike
underground
injection) can
produce fresh water
for crop irrigation,
domestic, and
industry use
Why Consider Coal Mine Methane Use in Brine Treatment?
Coal mines and coalbed methane wells often generate large volumes of water,
which may be highly contaminated with salt and other minerals. Because these
brines can alter water quality, they must be disposed of in compliance with
national and local statutes. Energy producers are continually seeking to improve
economics by decreasing water management costs.
Many coal mines drain methane from gob areas (collapsed rock over mined-out
areas). Mine ventilation air contaminates gob gas, often rendering it unsuitable for
pipeline injection. Therefore, mines usually vent this gas to the atmosphere instead
of using it. By using this gas as a fuel in the brine water treatment process, coal
mines can reduce the cost of desalination while helping to mitigate greenhouse
gas emissions.
Over the last three years, the use of coal mine methane in brine water
desalination has been successfully demonstrated at the Morcinek coal mine in
Poland's Upper Silesian Coal Basin. The process, designed by Aquatech Services,
ncorporated, integrates pre-treatment regimes, high-pressure reverse osmosis,
and a final concentration of the salt in a submerged combustion evaporator. The
pretreatment regime is specially designed for the complex waste streams typical
of coalbed brines. Following pretreatment, a reverse osmosis system converts the
brine wastewater to usable fresh water and a brine-salt slurry. Evaporation units,
fired by medium-quality gas recovered from the Morcinek Mine, further
concentrate the residual slurry to dry salts for commercial use or underground
disposal.
The demonstration project at the Morcinek Mine is treating more than 50 cubic
meters (314 barrels) of waste water per day. Testing of the demonstration
equipment began in 1994, with support from the U.S. Department of Energy, U.S.
Environmental Protection Agency, and Polish government. All results have been
positive, demonstrating efficiencies greater than anticipated, and validating and
confirming process reliability.
Some Facts About Using Coal Mine Methane for Waste Water Treatment
(based on results of the demonstration project at the Morcinek Mine)
• Treatment costs are competitive with those of underground injection
• Modular design allows for wide range of effluent volumes
• Process can recover more than 60% of the feed stream as usable fresh
water, suitable for domestic uses in many cases
• Process offers total brine volume reductions of greater than 95%
• Suitable for coalbed methane wells in unmined areas, as well as coal mining
operations
• Can use medium quality gas (as low as 50% methane)
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Example of Aquatech Wastewater Treatment Process
Chemical Pre-Treatment
Filter
High
Pressure
Pump
Reverse
Osmosis
Unit
250m3/ day
of brine,
TDS = 80 -120,000 ppm
v Pump
Submerged
Combustion
Evaporator
, Underground
Disposal
Comparison of Aquatech Process (Using Coal Mine Methane as
Combustion Fuel) to Underground Injection
Reverse Osmosis Followed Underground
Parameter by Combustion Injection
Evaporation (Aquatech} Only(}]
Typical capital costs ($US) $3,000 per m3/day $1,260 - $5,660 per m3/day
I $480 perbbl/day i $200 - $900 per bbl/day
Typical operating costs ($US)
$2.00-$3.00/m3(2)
$0.32-$0.47/barrel
$0.60- $4.70/m3
$0.10-$0.75/barrel
Conversion to usable water
YES
No
Production of usable salts
Uses coal mine methane'31
Total brine volume reduction
Life ot plant or well (years)
1 YES (in some cases) ]
I YES |
! >95%
! 10
No
No
0%
20
(1> Underground injection costs and well life vary widely according to site-specific conditions. Costs shown are from
1995 assessment of water disposal practices in the U.S., published by the Gas Research Institute (GRI), and from an
unpublished report on disposal of produced waters in the San Juan Basin prepared in 1992 for GRI. Costs shown do
not include off-site transportation. Twenty years is the average injection well life according to Warner and Lehr,
1977, An Introduction to the Technology of Subsurface Wastewater Injection: A symposium in Worthington, Ohio.
121 On a lease-purchase basis
(3) Coalbed methane can be an economical fuel source for treatment of water produced from coal mining
operations or coalbed methane wells. Use of methane produced during coal mining operations is especially
attractive in that in most cases, this methane would otherwise be vented to the atmosphere. This "waste gas" is a
valuable fuel source if mines use it, otherwise, it is a potent greenhouse gas that causes global warming.
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For More Information.
Energy producers are continually seeking to
improve economics by decreasing water
management costs. Coal mine methane
used as fuel for a wastewater treatment
process is an economic means of
wastewater management that can also
reduce emissions of methane to the
atmosphere.
EPA is aware of only one company
(Aquatech Services, Incorporated) whose
brine water treatment process has em-
ployed coal mine methane as a fuel.* To
obtain more information about this process,
contact:
John H. Tait, Principal
Aquatech Services, Incorporated
P.O. Box 946
Fair Oaks, CA 95628 USA
(916) 966-5141 (Phone and Fax)
e-mail 103220.1655@compuserve.com
Or contact EPA's Coalbed Methane Outreach
Program for information about this and other
profitable uses for coal mine methane:
Coalbed Methane Outreach Program
U.S. EPA
401 M Street, SW(6202J)
Washington, DC 20460 USA
(202) 564-9468 or (202) 564-9481
Fax: (202) 565-2077
e-mail: fernandez.roger@epa,gov
schultz.karl@epa.gov
http://www.epa.gov/coalbed
C O A
METHANE
OUTREACH
' R O C R A M
*The mention of products or services in this case study does not constitute an endorsement by EPA.
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