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dc.contributor.authorde Valk, Steef
dc.contributor.authorKhadem, Ahmad F.
dc.contributor.authorForeman, Christine M.
dc.contributor.authorLier, Jules B.
dc.contributor.authorde Kreuk, Merle K.
dc.identifier.citationde Valk S, Khadem AF, Foreman CM, van Lier JB, de Kreuk MK, “Physical and biochemical changes in sludge upon Tubifex tubifex predation,” Environmental Technology, 2017 June; 38(12):1524-1538. doi: 10.1080/09593330.2016.1236150.en_US
dc.description.abstractWorm predation (WP) on activated sludge leads to increased sludge degradation rates, irrespective of the type of worm used or reactor conditions employed. However, the cause of the increased sludge degradation rates remains unknown. This paper presents a comparative analysis of the physical and biochemical aspects of predated sludge, providing insight into the hydrolytic mechanisms underlying WP. To this end, the sessile worm Tubifex tubifex was used as a model oligochaete and was batch cultivated in an 18-L airlift reactor. Predation on activated sludge showed an average reduction rate of 12 ± 3.8%/d versus 2 ± 1.3%/d for endogenous respirated sludge. Sludge predation resulted in an increased release of inorganic nitrogen, phosphate and soluble chemical oxygen demand (sCOD). The sCOD consisted mainly of polysaccharides; however, fluorescence excitation emission matrix spectroscopy analysis also revealed the presence of Tryptophan-protein-like substances. Results suggest that the released polysaccharides contain a protein-like element. Additionally, soluble iron increased slightly in concentration after WP. The extent of hydrolysis seemed to reach an average plateau of about 40% volatile solids (VS) reduction after 4 days, which is substantially higher than the 29% VS reduction for endogenous decay of activated sludge after 30 days. Furthermore, T. tubifex predominantly consumed the protein fraction of the extracellular polymeric substances. Results suggest that that the worms specifically target a fraction of the sludge that is predominantly biodegradable under aerobic conditions, albeit at significantly higher degradation rates when compared to the endogenous decay of waste activated sludge.en_US
dc.rightsCC BY 4.0en_US
dc.titlePhysical and biochemical changes in sludge upon Tubifex tubifex predationen_US
mus.citation.journaltitleEnvironmental Technologyen_US
mus.identifier.categoryEngineering & Computer Scienceen_US
mus.relation.collegeCollege of Engineeringen_US
mus.relation.departmentCenter for Biofilm Engineering.en_US
mus.relation.departmentChemical & Biological Engineering.en_US
mus.relation.departmentChemical Engineering.en_US
mus.relation.departmentChemistry & Biochemistry.en_US
mus.relation.universityMontana State University - Bozemanen_US
mus.relation.researchgroupCenter for Biofilm Engineering.en_US
mus.contributor.orcidForeman, Christine M.|0000-0003-0230-4692en_US

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