Evaluation of Phytoremediation of Coal Bed Methane Product Water and Waters of Quality Similar to that Associated with Coal Bed Methane Reserves of the Powder River Basin, Montana and Wyoming
U.S. emphasis on domestic energy independence, along with advances in knowledge of vast biogenically sourced coalbed methane reserves at relatively shallow sub-surface depths with the Powder River Basin, has resulted in rapid expansion of the coalbed methane industry in Wyoming and Montana. Techniques have recently been developed which constitute relatively efficient drilling and methane gas recovery and extraction techniques. However, this relatively efficient recovery requires aggressive reduction of hydrostatic pressure within water-saturated coal formations where the methane is trapped. Water removed from the coal formation during pumping is typically moderately saline and sodium-bicarbonate rich, and managed as an industrial waste product. Current approaches to coalbed methane product water management include: surface spreading on rangeland landscapes, managed irrigation of agricultural crop lands, direct discharge to ephermeral channels, permitted discharge of treated and untreated water to perennial streams, evaporation, subsurface injection at either shallow or deep depths. A Department of Energy-National Energy Technology Laboratory funded research award involved the investigation and assessment of: (1) phytoremediation as a water management technique for waste water produced in association with coalbed methane gas extraction; (2) feasibility of commercial-scale, low-impact industrial water treatment technologies for the reduction of salinity and sodicity in coalbed methane gas extraction by-product water; and (3) interactions of coalbed methane extraction by-product water with landscapes, vegetation, and water resources of the Powder River Basin. Prospective, greenhouse studies of salt tolerance and water use potential of indigenous, riparian vegetation species in saline-sodic environments confirmed the hypothesis that species such as Prairie cordgrass, Baltic rush, American bulrush, and Nuttall's alkaligrass will thrive in saline-sodic environments when water supplies sourced from coalbed methane extraction are plentiful. Constructed wetlands, planted to native, salt tolerant species demonstrated potential to utilize substantial volumes of coalbed methane product water, although plant community transitions to mono-culture and limited diversity communities is a likely consequence over time. Additionally, selected, cultured forage quality barley varieties and native plant species such as Quail bush, 4-wing saltbush, and seaside barley are capable of sustainable, high quality livestock forage production, when irrigated with coalbed methane product water sourced from the Powder River Basin. A consequence of long-term plant water use which was enumerated is elevated salinity and sodicity concentrations within soil and shallow alluvial groundwater into which coalbed methane product water might drain. The most significant conclusion of these investigations was the understanding that phytoremediation is not a viable, effective technique for management of coalbed methane product water under the present circumstances of produced water within the Powder River Basin. Phytoremediation is likely an effective approach to sodium and salt removal from salt-impaired sites after product water discharges are discontinued and site reclamation is desired. Coalbed methane product water of the Powder River Basin is most frequently impaired with respect to beneficial use quality by elevated sodicity, a water quality constituent which can cause swelling, slaking, and dispersion of smectite-dominated clay soils, such as commonly occurring within the Powder River Basin. To address this issue, a commercial-scale fluid-bed, cationic resin exchange treatment process and prototype operating treatment plant was developed and beta-tested by Drake Water Technologies under subcontract to this award. Drake Water Technologies secured U.S. Patent No. 7,368,059-B2, 'Method for removal of benevolent cations from contaminated water', a beta Drake Process Unit (DPU) was developed and deployed for operation in the Powder River Basin. First year operation demonstrated an 84% sodium removal capacity. Greenhouse, laboratory and field research documented substantial likelihood of measurable alteration in soil chemistry, soil physical properties, and shallow alluvial aquifers in and below areas of sustained surface application through irrigation or water spreading or impoundment of coalbed methane product water in evaporation reservoirs within the Basin. Events of repeated wetting and drying of agricultural soils characteristic of the Powder River Basin with coalbed methane product water, followed by infrequent rainfall events, presents high probability circumstances of significant reductions in infiltration capacity and hydraulic conductivity of agricultural soils containing more than 34% smectite clay.
- Research Organization:
- Montana State Univ., Bozeman, MT (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG26-01BC15166
- OSTI ID:
- 950787
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
03 NATURAL GAS
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
COAL DEPOSITS
DOMESTIC ANIMALS
EVALUATION
HYDRAULIC CONDUCTIVITY
INDUSTRIAL WASTES
MANAGEMENT
METHANE
PHYSICAL PROPERTIES
POWDER RIVER BASIN
REMOVAL
SODIUM
SOIL CHEMISTRY
SOILS
WASTE WATER
WATER QUALITY
WATER RESOURCES
WATER TREATMENT
WATER USE