MICP via denitrification pathway under aerobic conditions

Document Type

Conference Proceeding

Publication Date

2025

Department

Department of Civil, Environmental, and Geospatial Engineering

Abstract

Microbially induced calcite precipitation (MICP) through the denitrification pathway is achieved when bacteria use nitrate as the electron acceptor to oxidize organic matter and generate ATP for growth. Most denitrifying bacteria are facultative anaerobes and in aerobic conditions, they use oxygen as the electron acceptor instead of nitrate. In other words, these bacteria can grow under aerobic conditions but they do not denitrify unless under anoxic conditions. This is because using oxygen yields more energy compared to denitrification. Recently, however, it has been shown that many bacteria (e.g., Paracoccus denitrificans) can denitrify under aerobic conditions even though it might result in lower levels of cell reproduction. These aerobic denitrifiers are commonly found in soil and aqueous environments including activated sludge used in wastewater treatment. In this study, batch experiments were conducted to confirm the occurrence of denitrification-MICP under aerobic conditions. Furthermore, samples from easily erodable sand dunes of the superior lake were treated via denitrification-MICP under aerobic conditions. Activated sludge from a local wastewater treatment facility was used as the source of denitrifiers. Carbonate content tests, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, Transmission Electron Microscopy, and X-ray diffraction analysis were conducted on treated soils. The results confirmed that different calcium carbonate polymorphs including calcite were precipitated and also showed that some salts and extracellular polymeric substances (EPS) were precipitated at the soil surface.

Publication Title

2025 International Conference on Bio-mediated and Bio-inspired Geotechnics (ICBBG2025)

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