Nuclear magnetic resonance imaging (NMRI) techniques were employed to ident
ify and selectively image biological films (biofilm) growing in aqueous sys
tems. Biofilms are shown to affect both the longitudinal (T-1) and transver
se (T-2) NMR relaxation time values of proximal water hydrogens. Results ar
e shown for biofilm growth experiments performed in a transparent parallel-
plate reactor. A comparison of biofilm distributions by both NMR and optica
l imaging yielded general agreement for both an open-flow system and an ide
alized porous system (the reactor without and with packed glass beads, resp
ectively). The selective imaging of biofilm by relaxation NMRI is dependent
upon the resolution of relaxation times for the fluid phases, dynamic rang
e, and signal-to-noise ratio, For open-flow systems, the use of a rapid and
quantitative T-2-sorted NMRI technique was preferred. For porous systems w
here T-2 values are generally more similar, a T-1-weighted technique was pr
eferred. (C) 1999 Academic Press.