Bioaugmentation (the process of adding selected strains/mixed cultures to wastewater reactors to
improve the catabolism of specific compounds, e.g. refractory organics, or overall COD) is a promising
technique to solve practical problems in wastewater treatment plants, and enhance removal efficiency.
The potential of this option can now be enhanced in order to take advantage of important advances in
the fields of microbial ecology, molecular biology, immobilization techniques and advanced bioreactor
design. Reports on bioaugmentation in WWT show the difficulties in evaluating the potential parameters
involved, leading frequently to inconclusive outcomes. Many studies have been carried out on the basis of
trial-and-error approaches, and it has been reported that reactors bioaugmented with pure cultures often
fail to perform as well as the pure cultures under laboratory conditions. As an interesting technical
challenge, the feasibility of bioaugmentation should ultimately be assessed by data from field implementation,
and this review highlights several promising areas to explore in the future.