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dc.contributor.supervisorOleszkiewicz, Jan (Civil Engineering)en
dc.contributor.authorDytczak, Magdalena Anna
dc.date.accessioned2008-09-10T13:34:20Z
dc.date.available2008-09-10T13:34:20Z
dc.date.issued2008-09-10T13:34:20Z
dc.identifier.citationDytczak M. A., Londry K. L., Siegrist H. and Oleszkiewicz J. A. (2006). Extracellular polymers in partly ozonated return activated sludge: impact on flocculation and dewaterability” Wat Sci and Tech 54(9), 155-164en
dc.identifier.citationDytczak M. A., Londry K. L., Siegrist H. and Oleszkiewicz J. A. (2007). Ozonation reduces sludge production and improves denitrification. Wat Res 41, 543-550en
dc.identifier.citationDytczak M. A., Londry K. L. and Oleszkiewicz J. A. (2008a). Biotransformation of estrogens in nitrifying activated sludge under aerobic and alternating anoxic/aerobic conditions. Wat Env Res, 80, 47-52en
dc.identifier.citationDytczak M. A., Londry K. L. and Oleszkiewicz J. A. (2008b). Nitrifying genera in activated sludge may influence nitrification rates. Wat Env Res, 80, 388-396en
dc.identifier.citationDytczak M. A., Londry K. L. and Oleszkiewicz J. A. (2008c). Activated sludge operational regime has significant impact on the type of nitrifying community and its nitrification rates. Wat Res 42, 2320-2328en
dc.identifier.urihttp://hdl.handle.net/1993/3062
dc.description.abstractThe effectiveness of partial ozonation of return activated sludge for enhancing denitrification and waste sludge minimization were examined. A pair of nitrifying sequencing batch reactors was operated in either aerobic or alternating anoxic/aerobic conditions, with one control and one ozonated reactor in each set. The amount of solids decreased with the ozone dose. Biomass in the anoxic/aerobic reactor was easier to destroy than in the aerobic one, generating approximately twice as much soluble chemical oxygen demand (COD) by cell lysis. Increased COD favoured production of extracellular polymers in ozonated reactors, enhancing flocculation and improving settling. Floc stability was also strengthened in prolonged operation in alternating treatment, resulting in declined solids destruction. Dewaterability was better in alternating reactors than in aerobic ones indicating that incorporation of an anoxic zone for biological nutrient removal leads to improvement in sludge dewatering. The negative impact of ozonation on dewaterability was minimal in terms of the long-term operation. Ozone successively destroyed indicator estrogenic compounds, contributing to total estrogen removal from wastewater. Denitrification rate improved up to 60% due to additional carbon released by ozonation. Nitrification rates deteriorated much more in the aerobic than in the alternating reactor, possibly as a result of competition created by growth of heterotrophs receiving the additional COD. Overall, ozonation provided the expected benefits and had less negative impacts on processes in the alternating treatment, although after prolonged operation, benefits could become less significant. The alternating anoxic/aerobic reactor achieved twice the nitrification rates of its aerobic counterpart. Higher removal rates of estrogens were associated with higher nitrification rates, supporting the contention that the nitrifying biomass was responsible for their removal. The alternating treatment offered the better estrogen biodegradation. Microbial populations in both reactors were examined with fluorescent in situ hybridization. Dominance of rapid nitrifiers like Nitrosomonas and Nitrobacter (79.5%) in the alternating reactor, compared to a dominance of slower nitrifiers like Nitrosospira and Nitrospira (78.2%) in the aerobic reactor were found. The findings are important to design engineers, as reactors are typically designed based on nitrifiers’ growth rate determined in strictly aerobic conditions.en
dc.format.extent1912307 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoengen_US
dc.rightsinfo:eu-repo/semantics/openAccess
dc.subjectnitrificationen
dc.subjectdenitrificationen
dc.subjectozonationen
dc.subjectsludge minimizationen
dc.subjectmicrobial ecologyen
dc.subjectactivated sludgeen
dc.subjectwastewater treatmenten
dc.subjectflocculationen
dc.subjectsettlingen
dc.subjectdewateringen
dc.subjectendocrine disruptorsen
dc.titleUsing ozonation and alternating redox potential to increase nitrogen and estrogen removal while decreasing waste activated sludge productionen
dc.typeinfo:eu-repo/semantics/doctoralThesis
dc.typedoctoral thesisen_US
dc.degree.disciplineCivil Engineeringen_US
dc.contributor.examiningcommitteeVanGulck, Jamie (Civil Engineering) Tenuta, Mario (Soil Science) Daigger, Glen (CH2MHill, Denver CO)en
dc.degree.levelDoctor of Philosophy (Ph.D.)en_US
dc.description.noteOctober 2008en


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