title: Impact of septic compounds and operational conditions on the microbiology of an activated sludge system.
abstract: 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. A significant correlation was found between the sludge volume index, the abundance of Type 021N, and the propionic acid (PA) concentration in the primary clarified effluent. PA also induced a significant change in the flocculating bacteria size distribution determined by digital imaging. Consequently, the correlation observed between PA and Type 021N bulking is an indirect effect of inhibition of floc-forming microorganisms, giving a competitive advantage to filaments.
authors.affiliation: Paprican, 570 boul. St-Jean, Pointe-Claire, QC, Canada.
authors.forename: Carl
authors.initials: C
authors.lastname: Pelletier
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Fitzsimmons
authors.forename: Sophie
authors.initials: S
authors.lastname: Deschênes
authors.forename: Michael
authors.initials: M
authors.lastname: Paice
mesh_terms: D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D007220:Industrial Waste; D009930:Organic Chemicals / Q000737:chemistry; D010209:Paper; D011422:Propionates / Q000737:chemistry; D012722:Sewage / Q000382:microbiology*; D013457:Sulfur Compounds / Q000737:chemistry; D041962:Thiotrichaceae / Q000145:classification / Q000254:growth & development* / Q000378:metabolism; D013997:Time Factors; D014835:Volatilization; D014865:Waste Disposal, Fluid / Q000379:methods*; D015045:Zoogloea / Q000145:classification / Q000254:growth & development* / Q000378:metabolism
chemical_list: D007220:Industrial Waste; D009930:Organic Chemicals; D011422:Propionates; D012722:Sewage; D013457:Sulfur Compounds; C029658:propionic acid