Physiochemical Treatment Options for High-Conductivity Coal Mining Runoff

In recent years, the excessive specific conductance (SC) of Appalachian coal mining runoff waters has become a parameter of concern with the EPA due to its negative effect on aquatic life and water quality. In order to comply with the EPA guidance suggesting an effluent SC of 500 µS/cm, the Appalachian Research Initiative for Environmental Science (ARIES) Center at Virginia Tech requested that testing be done to determine the most effective technologies for reduction of SC. Runoff water was collected from two sites in southwestern Virginia and characterized to determine the source of SC in the water. The main contributing ions were determined to be Na⁺, Mg²⁻, Ca²⁺, and SO₄²⁻. Testing was performed to assess the possibility of using the speciation software, MINEQL+, with a set of empirical equations which predict SC using ionic composition for natural waters with a low to medium SC. The physicochemical treatment methods tested were ion exchange, excess lime-soda softening, and the Cost Effective Sulfate Removal (CESR) process. Both cation (H⁺ exchanger) and anion (Cl⁻ exchanger) exchange media were tested separately in batch reactors, which resulted in a higher effluent SC than initial SC. The softening method investigated, excess lime-soda softening, also resulted in increased SC levels because non-carbonate hardness levels were high and carbonate concentrations were low. The CESR process successfully lowered SC from 1,500-2,500 µS/cm to below the proposed EPA limit of 500 µS/cm. The success of this process was due to its ability to remove more than 85% of the calcium, magnesium, and sulfate from the water, which together accounted for more than 90% of ions in the source water.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Environmental Engineering

Department dc:contributor.department

Civil and Environmental Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2017

Author dc:creator

• Grey, Catherine Vyvian

Chairs dc:contributor.committeechair

• Boardman, Gregory D.
• Vikesland, Peter J.

Committee member dc:contributor.committeemember

• Parks, Jeffrey L.

• Ion Exchange
• Softening
• Chemical Softening
• Calcium
• Magnesium
• Sulfate
• Suphate
• Specific Conductance
• Cost Effective Sulfate Removal Process
• CESR Process
• Total Dissolved Solids
• TDS

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

vt_gsexam:10045

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/85011