title: Disruption of biofilms from sewage pipes under physical and chemical conditioning.
abstract: Biofilms grown inside two sewage collecting pipes located in industrial and residential areas are studied. Bacterial biomass inside three layers of biofilms was evaluated. Biofilm cohesion under different mixing rate and ionic strength was also investigated. Effects of physical and chemical parameters in the biofilms were evaluated by monitoring turbidity, chemical and biochemical oxygen demands. Extracted organic matter from biofilms was partitioned to polar, aromatic and saturated fractions using activated silica column chromatography. Results revealed that bacterial biomass growth depending on biofilm thickness and stratification. The most loaded stratum in bacterial biomass was the sewage-biofilm interface stratum that represented 51% of the total bacterial biomass. Stirring rate and ionic strength of mono- and bivalent salts showed a major influence in biofilm disruption. The stirring time enhanced the exchange dynamic and matter capture between biofilm fragments at the critical stirring rate 90 r/min. Sodium chloride showed the dispersing effect on biofilms in suspension, and decreased the BOD5 (biochemical oxygen demand) beyond the physiological salt concentration.
authors.affiliation: Holy Spirit University of Kaslik (USEK), Faculty of Sciences and Computer Engineering Department of Chemistry and Life Sciences, Water and Environment Laboratory, P.B. 446, Jounieh, Lebanon.
authors.forename: Charbel
authors.initials: C
authors.lastname: Mahfoud
authors.forename: Antoine
authors.initials: A
authors.lastname: El Samrani
authors.forename: Rita
authors.initials: R
authors.lastname: Mouawad
authors.forename: Walid
authors.initials: W
authors.lastname: Hleihel
authors.forename: Rim
authors.initials: R
authors.lastname: El Khatib
authors.forename: Bruno S
authors.initials: BS
authors.lastname: Lartiges
authors.forename: Naïm
authors.initials: N
authors.lastname: Ouaïni
mesh_terms: D001419:Bacteria / Q000187:drug effects; D018407:Bacterial Physiological Phenomena / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D009930:Organic Chemicals / Q000737:chemistry / Q000494:pharmacology; D009994:Osmolar Concentration; D012722:Sewage / Q000382:microbiology*; D012995:Solubility; D013997:Time Factors; D014867:Water / Q000737:chemistry / Q000494:pharmacology
chemical_list: D009930:Organic Chemicals; D012722:Sewage; D014867:Water