Biodecontamination of concrete
- Idaho National Engineering Lab., Idaho Falls, ID (United States)
- British Nuclear Fuels P.C., Preston (United Kingdom)
A novel technology for biologically decontaminating concrete is being jointly developed by scientists at the Idaho National Engineering Laboratory (INEL) and British Nuclear Fuels plc (BNFL). The technology exploits a naturally occurring phenomenon referred to as microbially influenced degradation (MID) in which bacteria produce acids that dissolve the cement matrix of concrete. Most radionuclide contamination of concrete is fixed in the outer few mm of the concrete surface. By capturing and controlling this natural process, a biological method of removing the surface of concrete to depths up to several mm is being developed. Three types of bacteria are known to be important in MID of concrete: nitrifying bacteria that produce nitric acid, sulfur oxidizing bacteria that produce sulfuric acid, and certain heterotrophic bacteria that produce organic acids. An investigation of natural environments demonstrated with scanning electron microscopy the presence of bacteria on concrete surfaces of a variety of structures, such as bridges and dams, where corrosion is evident. Enumeration of sulfur oxidizing and nitrifying bacteria revealed their presence and activity on structures to varying degrees in different environments. Under ideal conditions, Thiobacillus thiooxidans, a sulfur oxidizing bacteria, attached to and colonized the surface of concrete specimens. Over 1mm depth of material from a 10 cm x 10 cm square surface was removed in 68 days in the Thiobacillus treated specimen compared to a sterile control. Laboratory and field demonstrations are currently being conducted using experimental chambers designed to be mounted directly to concrete surfaces where radionuclide contamination exists. Data is being obtained in order to determine actual rates of surface removal and limitations to the system. This information will be used to develop a full scale decontamination technology.
- DOE Contract Number:
- AC07-94ID13223
- OSTI ID:
- 476551
- Report Number(s):
- CONF-960804-Vol.3; TRN: 97:009092
- Resource Relation:
- Conference: SPECTRUM `96: international conference on nuclear and hazardous waste management, Seattle, WA (United States), 18-23 Aug 1996; Other Information: PBD: 1996; Related Information: Is Part Of Proceedings of the international topical meeting on nuclear and hazardous waste management (SPECTRM `96): Volume 3; PB: 843 p.
- Country of Publication:
- United States
- Language:
- English
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