AWWA JAW34181

Fluidized-bed denitrification of surface water with methanol as the carbon source is currently being studied in Belgium. Residual methanol and microbial excretion products increased the dissolved assimilable organic carbon in the reactor effluent. Hyphomicrobium sp. was isolated as a methylotrophic denitrifier of primary importance. The anoxic denitrifying environment apparently provides a favorable niche for a large diversity of associated bacterial strains. Hydraulic shear resulted in the constant washout of these indicator species from the reactor. Thus, the microbiological quality of the effluent is altered by the denitrifying process, and the treated water has to be further subjected to filtration and disinfection in order to guarantee the removal of residual organic carbon and prevent breakthrough of indicator organisms. Includes 56 references, tables, figures.