The Use of Microbial Induced Calcite Precipitation to Reduce Trace Element Leaching from Fly Ash

Abstract

North Carolina has recently been facing issues associated with the storage of coal ash, specifically preventing trace elements found in coal ash from leaching into the local groundwater. The research program presented herein focuses on reducing the leachability of trace elements found in coal ash using bio-mediated methods. Microbial induced calcite precipitation (MICP) is used to immobilize trace elements within the fly ash. The MICP process is initiated within ponded fly ash material set up in soil columns, and effluent is collected from the treated fly ash material. The concentrations of the trace elements are measured using inductively coupled plasma mass spectrometry (ICP-MS). The concentrations within the MICP-treated fly ash effluent are compared to baseline fly ash effluent. The MICP treatment process is also applied to dry fly ash material that may be used within construction projects. The MICP treatment process was applied to fly ash material in a similar manner as moisture conditioning during compaction. The MICP treatment process was allowed to take place, then effluent samples were collected from percolating water. The MICP-treated leachate was compared to that of a baseline compacted fly ash sample and compared to the results from the ponded fly ash.