title: Effect of aging, time, and temperature on fecal coliform counts during centrifugal dewatering and role of centrate in growth inhibition.
abstract: Recent studies have reported significant increases in fecal coliform counts in anaerobically digested sludge soon after centrifuge dewatering. The reasons behind these increases are not yet understood. This study investigated the role of inhibitor substances on the reactivation and regrowth of sludge bacteria and the effect of storage time and temperature on their growth behavior. The study consisted of full- and laboratory-scale testing, and quantified the microbiological and chemical characteristics of sludge, cake, and centrate samples under different temperatures and aging times. Significant reactivation was not observed at the treatment plants tested. Results showed that the regrowth phenomenon is not observed for all sludges, and differences in sludge characteristics and treatment processes may play a role in determining the regrowth behavior of sludge. Centrate collected from one of the treatment plants had an inhibitory effect on the growth of fecal coliform and was four times more toxic than cake to the bacteria. Chemical analyses of the centrate identified sulfide as one of the possible inhibitory compounds. The results also showed that fecal coliform have different growth and survival behavior compared to other sludge bacteria.
authors.affiliation: Department of Civil and Environmental Engineering, Carleton University, Ottawa, Ontario, Canada.
authors.forename: Julie
authors.initials: J
authors.lastname: Gardner
authors.forename: Banu
authors.initials: B
authors.lastname: Ormeci
mesh_terms: D000255:Adenosine Triphosphate / Q000032:analysis; D004755:Enterobacteriaceae / Q000302:isolation & purification*; D005243:Feces / Q000382:microbiology*; D012722:Sewage; D013696:Temperature; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000379:methods*; D014871:Water Microbiology
chemical_list: D012722:Sewage; D000255:Adenosine Triphosphate