Impact of septic compounds and operational conditions on the microbiology of an activated sludge system.

In activated sludge (AS) biotreatment, septic compounds such as volatile organic acids and reduced sulphur compounds have been frequently cited as a major cause of Thiothrix and Type 021N filamentous bulking. These filaments are common in Canadian pulp and paper biotreatment systems, where they cause settling problems in secondary clarifiers. We conducted a 14-week study of a TMP/newsprint mill effluent to characterize the septic compounds entering the biotreatment, and to determine correlations with AS biomass characteristics and biotreatment operating parameters.

Molecular characterization of microbial communities in Canadian pulp and paper activated sludge and quantification of a novel Thiothrix eikelboomii-like bulking filament.

We examined the microbial community structure and quantified the levels of the filamentous bulking organism Thiothrix eikelboomii in samples of activated sludge mixed liquor suspended solids (MLSS) from Canadian pulp and paper mills. Libraries of chaperonin 60 (cpn60) gene sequences were prepared from MLSS total microbial community DNA and each was compared with cpnDB, a reference database of cpn60 sequences (http://cpndb.cbr.