title: Sulfide and methane production in sewer sediments.
abstract: Recent studies have demonstrated significant sulfide and methane production by sewer biofilms, particularly in rising mains. Sewer sediments in gravity sewers are also biologically active; however, their contribution to biological transformations in sewers is poorly understood at present. In this study, sediments collected from a gravity sewer were cultivated in a laboratory reactor fed with real wastewater for more than one year to obtain intact sediments. Batch test results show significant sulfide production with an average rate of 9.20 ± 0.39 g S/m(2)·d from the sediments, which is significantly higher than the areal rate of sewer biofilms. In contrast, the average methane production rate is 1.56 ± 0.14 g CH4/m(2)·d at 20 °C, which is comparable to the areal rate of sewer biofilms. These results clearly show that the contributions of sewer sediments to sulfide and methane production cannot be ignored when evaluating sewer emissions. Microsensor and pore water measurements of sulfide, sulfate and methane in the sediments, microbial profiling along the depth of the sediments and mathematical modelling reveal that sulfide production takes place near the sediment surface due to the limited penetration of sulfate. In comparison, methane production occurs in a much deeper zone below the surface likely due to the better penetration of soluble organic carbon. Modelling results illustrate the dependency of sulfide and methane productions on the bulk sulfate and soluble organic carbon concentrations can be well described with half-order kinetics.
authors.affiliation: Advanced Water Management Centre, The University of Queensland, QLD, Australia.
authors.forename: Yiwen
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Advanced Water Management Centre, The University of Queensland, QLD, Australia.
authors.forename: Bing-Jie
authors.initials: BJ
authors.lastname: Ni
authors.affiliation: Advanced Water Management Centre, The University of Queensland, QLD, Australia; LEQUIA, Institute of the Environment, University of Girona, Campus de Montilivi, E-17071 Girona, Catalonia, Spain.
authors.forename: Ramon
authors.initials: R
authors.lastname: Ganigué
authors.affiliation: Advanced Water Management Centre, The University of Queensland, QLD, Australia.
authors.forename: Ursula
authors.initials: U
authors.lastname: Werner
authors.affiliation: Advanced Water Management Centre, The University of Queensland, QLD, Australia.
authors.forename: Keshab R
authors.initials: KR
authors.lastname: Sharma
authors.affiliation: Advanced Water Management Centre, The University of Queensland, QLD, Australia. Electronic address: z.yuan@awmc.uq.edu.au.
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Yuan
mesh_terms: D019149:Bioreactors; D019015:Geologic Sediments / Q000032:analysis*; D008697:Methane / Q000378:metabolism*; D064307:Microbiota; D008962:Models, Theoretical; D012722:Sewage / Q000737:chemistry; D013431:Sulfates / Q000378:metabolism*; D013440:Sulfides / Q000378:metabolism*
chemical_list: D012722:Sewage; D013431:Sulfates; D013440:Sulfides; D008697:Methane
keywords: Methane; Microbial profiling; Modelling; Sediment; Sewer; Sulfide