Conventional or Bentonite-Polymer GCLs for Coal Combustion Product Leachates.pdf

Yu Tan, University of Wisconsin-Madison
Craig Benson, University of Wisconsin-Madison
Jimmy Youngblood, Solmax Inc.

Description

Conventional or Bentonite-Polymer GCLs for Coal Combustion Product Leachates? Authors Mr. Yu Tan - United States - University of Wisconsin-Madison Dr. Craig Benson - United States - University of Wisconsin-Madison Mr. Jimmy Youngblood - United States - Solmax Inc. Abstract Hydraulic conductivity of geosynthetic clay liners (GCLs) containing sodium bentonite (NaB) or bentonite-polymer composite (BPC) was evaluated using seven coal combustion product (CCP) leachates having various ionic strength (0.0042 to 2.2 M, dilute to concentrated). Four GCLs were evaluated, including two NaB GCLs containing bentonite with different granule sizes and two BPC GCLs containing dry mixtures of bentonite and polymer granules. The BPCs contained the same bentonite and polymer, but had different polymer loading (3.2 vs. 6.8%). Hydraulic conductivity of the NaB GCLs increased with increasing ionic strength of the leachate. In contrast, hydraulic conductivity of BPC GCLs was low and insensitive to ionic strength. When the CCP leachate had ionic strength higher than 0.1M, hydraulic conductivity of NaB GCLs exceeded 1x10-10 m/s, whereas hydraulic conductivity of BPC GCLs was below 3x10-11 m/s. NaB GCLs with smaller granules had lower hydraulic conductivity than those with larger granules, particularly at higher ionic strength. The BPC GCL with higher polymer loading had lower hydraulic conductivity than the BPC GCL with lower polymer loading in all cases. These findings suggest that NaB GCLs can be used to contain dilute CCP leachates, whereas BPC GCLs are more effective for high ionic strength CCP leachates.

 
May 16th, 9:30 AM May 16th, 10:00 AM

Conventional or Bentonite-Polymer GCLs for Coal Combustion Product Leachates.pdf

Grand Rapids, Michigan

Conventional or Bentonite-Polymer GCLs for Coal Combustion Product Leachates? Authors Mr. Yu Tan - United States - University of Wisconsin-Madison Dr. Craig Benson - United States - University of Wisconsin-Madison Mr. Jimmy Youngblood - United States - Solmax Inc. Abstract Hydraulic conductivity of geosynthetic clay liners (GCLs) containing sodium bentonite (NaB) or bentonite-polymer composite (BPC) was evaluated using seven coal combustion product (CCP) leachates having various ionic strength (0.0042 to 2.2 M, dilute to concentrated). Four GCLs were evaluated, including two NaB GCLs containing bentonite with different granule sizes and two BPC GCLs containing dry mixtures of bentonite and polymer granules. The BPCs contained the same bentonite and polymer, but had different polymer loading (3.2 vs. 6.8%). Hydraulic conductivity of the NaB GCLs increased with increasing ionic strength of the leachate. In contrast, hydraulic conductivity of BPC GCLs was low and insensitive to ionic strength. When the CCP leachate had ionic strength higher than 0.1M, hydraulic conductivity of NaB GCLs exceeded 1x10-10 m/s, whereas hydraulic conductivity of BPC GCLs was below 3x10-11 m/s. NaB GCLs with smaller granules had lower hydraulic conductivity than those with larger granules, particularly at higher ionic strength. The BPC GCL with higher polymer loading had lower hydraulic conductivity than the BPC GCL with lower polymer loading in all cases. These findings suggest that NaB GCLs can be used to contain dilute CCP leachates, whereas BPC GCLs are more effective for high ionic strength CCP leachates.