Journals Proceedings

Abstract

This study focused on identification of denitrifiers that can be used to achieve microbial self-healing concrete. By using heat treatment and minimal medium, 9 denitrifying strains were isolated from soil. Upon identification of the strains, their capability of handling dehydration stress was investigated. Qualifying 7 strains were further investigated at N:P ratio of 70:1. Finally, 2 strains, Pseudomonas aeruginosa and Diaphorobacter nitroreducens, were selected and investigated at pH 7, pH 9.5 and pH 13 with and without protection. As a protective carrier diatomaceous earth and expanded clay were used. Significant activity observed at pH 9.5 and with protection both strains could survive pH 13 for 14 days and reduced 20-30 mg/L NO3- in 4 days after the pH adjustment to ~10. Overall, the results indicated that Pseudomonas aeruginosa and Diaphorobacter nitroreducens can resist mild heat, dehydration, starvation and relatively alkali environment, which are the main concerns in use of bacteria for concrete structures.