Biodegradation of monoethanolamine in soil monitored by electrical conductivity measurement: an observational approach

Monoethanolamine (MEA) is commonly used by the natural gas industry to remove acid gases from the natural gas stream. A series of pan test studies was conducted to examine the biodegradability of MEA in soil recovered from a decommissioned sour gas processing plant site. Test results indicate that MEA was successfully biodegraded or transformed into simple compounds under aerobic and anaerobic conditions. The electrical conductivity (EC) of the soil evolved with changing chemical conditions of its by-products during degradation of MEA. Based on experimental observations, five ranges of EC were correlated with five geochemical zones consisting of various concentrations of MEA and its by-products. The five ranges of EC were translated into equivalent in situ EC ranges. Using these in situ EC ranges, an electrical resistivity tomography image was used to create a geochemical interpretation of the subsurface beneath the plant site. The geochemical interpretation can provide useful information for detailed site assessment and remediation design.Key words: electrical conductivity, biodegradation, monoethanolamine, ammonia, acetate, electrical resistivity tomography, site characterization, observational approach.