A geochemical module for "AMDTreat" to compute caustic quantity, effluent quantity, and sludge volume

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Abstract

Treatment with caustic chemicals typically is used to increase pH and decrease concentrations of dissolved aluminum, iron, and/or manganese in largevolume, metal-laden discharges from active coal mines. Generally, aluminum and iron can be removed effectively at near-neutral pH (6 to 8), whereas active manganese removal requires treatment to alkaline pH (~10). The treatment cost depends on the specific chemical used (NaOH, CaO, Ca(OH)2, Na2CO3, or NH3) and increases with the quantities of chemical added and sludge produced. The pH and metals concentrations do not change linearly with the amount of chemical added. Consequently, the amount of caustic chemical needed to achieve a target pH and the corresponding effluent composition and sludge volume can not be accurately determined without empirical titration data or the application of geochemical models to simulate the titration of the discharge water with caustic chemical(s). The AMDTreat computer program (http://amd.osmre.gov/ ) is widely used to compute costs for treatment of coal-mine drainage. Although AMDTreat can use results of empirical titration with industrial grade caustic chemicals to compute chemical costs for treatment of net-acidic or net-alkaline mine drainage, such data are rarely available. To improve the capability of AMDTreat to estimate (1) the quantity and cost of caustic chemicals to attain a target pH, (2) the concentrations of dissolved metals in treated effluent, and (3) the volume of sludge produced by the treatment, a titration simulation is being developed using the geochemical program PHREEQC (wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc/) that will be coupled as a module to AMDTreat. The simulated titration results can be compared with or used in place of empirical titration data to estimate chemical quantities and costs. This paper describes the development, evaluation, and potential utilization of the PHREEQC titration module for AMDTreat.

Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title A geochemical module for "AMDTreat" to compute caustic quantity, effluent quantity, and sludge volume
Year Published 2010
Language English
Publisher American Society of Mining and Reclamation
Contributing office(s) Pennsylvania Water Science Center
Description 24 p.
Larger Work Type Conference Paper
Larger Work Title Joint Mining Reclamation Conference 2010: 27th Annual Meeting of the American Society of Mining and Reclamation, 12th Annual Pennsylvania Abandoned Mine Reclamation Conference and 4th Annual Appalachian Regional Reforestation Initiative Mined Land Reforestation Conference, Pittsburgh, Pennsylvania, USA, 5-11 June 2010
First page 1413
Last page 1436
Conference Title Joint Mining Reclamation Conference 2010
Conference Location Pittsburgh, Pennsylvania
Conference Date June 5-11 2010
Country United States
State Pennsylvania
Other Geospatial "Cal Pike" coal mine, Western Pennsylvania
Online Only (Y/N) N
Additional Online Files (Y/N) N