| The removal of the cyanobacterial toxin microcystin-LR by slow and rapid drinking water biofilters, the presence of the microcystin-degrading bacteria in operating biofilters, the impact of backwashing on the removal of microcystin by biofiltration, and the prediction of microcystin-LR removal using a nonsteady-state biofilm model were investigated. A newly recognized microcystin-LR degrader, Morganella morganii, exists in Lake Mead and operating active biofilters. The results of the biodegradation tests indicated that addition of a carbon source, in the form of biodegradable NOM, significantly delayed the degradation of microcystin-LR. The biofiltration experiments demonstrated that at steady-state, biofiltration may be a potential technology for the removal of microcystin-LR under slow and rapid conditions. However, the impact of backwashing on microcystin removal, points out some limitations for this treatment process. The results of biofilm model prediction using estimated biofilm thickness indicated a better agreement with the TOC experimental data than with the microcystin's data. |
