This study evaluated the bioremediation of atrazine herbicide contaminated agricultural soil under
different bioremediation strategies using indigenous
Pseudomonas aeruginosa
,
Bacillus subtilis
and
Aspergillus niger
as bioaugmentation agents and poultry droppings as biostimulation agent. The results showed that bioaugmentation
with
Pseudomonas aeruginosa, bioaugmentation with
Bacillus subtilis, bioaugmentation with
Aspergillus niger,
bioaugmentation with bacterial-fungal consortium (
Pseudomonas aeruginosa,
Bacillus subtilis and
Aspergillus niger),
biostimulation with poultry droppings, and combined biougmentation and biostimulation (
Pseudomonas aeruginosa,
Bacillus subtilis,
Aspergillus niger and poultry droppings) resulted in maximum atrazine biodegradation of about 97%,
95%, 84%, 99%, 100% and 100%, respectively. The kinetics of atrazine biodegradation in the soil were modelled using
first-order kinetic model and the biodegradation half-life estimated. The first order kinetic model adequately described
the kinetics of atrazine biodegradation in soil under the different bioremediation strategies. The rate constants (
k
1 ) of
atrazine biodegradation in soil subjected to bioaugmentations with
Pseudomonas aeruginosa,
Bacillus subtilis,
Aspergillus niger, and bacterial-fungal consortium ranges between 0.059 day
-1 and 0.191 day
-1 while for that subjected
to natural bioattenuation, biostimulation and combined bioaugmentation and biostimulation are 0.026 day
-1, 0.164 day
-1 and 0.279 day
-1, respectively. The half-life (
t
1/ 2 ) of atrazine biodegradation in soil under natural bioattenuation was
obtained to be 26.7 days. This was reduced to between 2.5 and 11.7 days under the application of bioaugmentation,
biostimulation and combined bioaugmentation and biostimulation strategies. The bioremediation efficiencies of the
different bioremediation strategies in influencing atrazine biodegradation or removal is of the following order:
Combined bioaugmentation and biostimulation > Bioaugmentation with bacterial-fungal consortium > Biostimulation
with poultry droppings > Bioaugmentation with
Pseudomonas aeruginosa > Bioaugmentation with
Bacillus subtilis >
Bioaugmentation with
Aspergillus niger > Natural bioattenuation.