The inhibiting effect of 14 typical creosote compounds on the aerobic
degradation of toluene was studied in batch experiments. Four NSO-comp
ounds (pyrrole, 1-methylpyrrole, thiophene, and benzofuran) strongly i
nhibited the degradation of toluene. When the NSO-compounds were prese
nt together with toluene, little or no degradation of toluene was obse
rved during 16 days of incubation, compared with a total removal of to
luene within 4 days when the four compounds were absent. Indole (an N-
compound) and three phenolic compounds (phenol, o-cresol, and 2,4-dime
thylphenol) also inhibited the degradation of toluene, though the effe
ct was much weaker that of the four NSO-compounds. O-xylene, p-xylene,
naphthalene and 1-methylnaphthalene seemed to stimulate the degradati
on even though the influence was very weak. No effects of benzothiophe
ne (an S-compound) and quinoline (an N-compound) were observed. Benzof
uran (an O-compound) was identified as the compound that most inhibite
d the degradation of toluene. An effect could be detected even at low
concentrations (40 mu g/l).