The removal of nitrogen and phosphorus in anoxic-aerobic digestion of waste activated sludge from biological nutrient removal systems

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dc.contributor.advisorEkama, George Aen_ZA
dc.contributor.authorVogts, Michelleen_ZA
dc.date.accessioned2017-05-16T07:55:59Z
dc.date.available2017-05-16T07:55:59Z
dc.date.issued2015en_ZA
dc.description.abstractBiological nutrient removal (BNR) activated sludge systems (designed and operated with an additional function of biologically removing nitrogen and phosphorus) produce a waste activated sludge (WAS) that is rich in nitrogen (N) and phosphorus (P). When digested, this nitrogen and phosphorus are released, producing a dewatering liquor high in ammonia or nitrate and phosphate. Not only does this dewatering liquor need to be treated, but the phosphate also precipitates in the digester and surrounding pipework, resulting in loss of digester capacity and pipe blockages. This investigation studies anoxic-aerobic digestion (aerobic digestion with intermittent aeration), as an alternative digestion of BNR WAS. Aerobic digestion is simple to operate – being an extension of the activated sludge process, requiring aeration and limited recycling. This compared with anaerobic digestion which is complex to operate requiring airtight containers with fire risk, heating and much recycling. In anoxic-aerobic digestion, the nitrogen is removed by nitrification-denitrification, which has the added advantages of reducing the digester's oxygen demand and recovering some of the alkalinity lost in nitrification. Phosphate is precipitated in the digester - a convenient location. This results in a digester dewatering liquor low in nitrogen and phosphorus (<5 mgNH₄-N/l, <15 mgNO₃- N/l and 20 to 30 mgPO₄-P/l) that can be returned to the activated sludge plant without overloading it.en_ZA
dc.identifier.apacitationVogts, M. (2015). <i>The removal of nitrogen and phosphorus in anoxic-aerobic digestion of waste activated sludge from biological nutrient removal systems</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Water Research Group. Retrieved from http://hdl.handle.net/11427/24307en_ZA
dc.identifier.chicagocitationVogts, Michelle. <i>"The removal of nitrogen and phosphorus in anoxic-aerobic digestion of waste activated sludge from biological nutrient removal systems."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Water Research Group, 2015. http://hdl.handle.net/11427/24307en_ZA
dc.identifier.citationVogts, M. 2015. The removal of nitrogen and phosphorus in anoxic-aerobic digestion of waste activated sludge from biological nutrient removal systems. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Vogts, Michelle AB - Biological nutrient removal (BNR) activated sludge systems (designed and operated with an additional function of biologically removing nitrogen and phosphorus) produce a waste activated sludge (WAS) that is rich in nitrogen (N) and phosphorus (P). When digested, this nitrogen and phosphorus are released, producing a dewatering liquor high in ammonia or nitrate and phosphate. Not only does this dewatering liquor need to be treated, but the phosphate also precipitates in the digester and surrounding pipework, resulting in loss of digester capacity and pipe blockages. This investigation studies anoxic-aerobic digestion (aerobic digestion with intermittent aeration), as an alternative digestion of BNR WAS. Aerobic digestion is simple to operate – being an extension of the activated sludge process, requiring aeration and limited recycling. This compared with anaerobic digestion which is complex to operate requiring airtight containers with fire risk, heating and much recycling. In anoxic-aerobic digestion, the nitrogen is removed by nitrification-denitrification, which has the added advantages of reducing the digester's oxygen demand and recovering some of the alkalinity lost in nitrification. Phosphate is precipitated in the digester - a convenient location. This results in a digester dewatering liquor low in nitrogen and phosphorus (<5 mgNH₄-N/l, <15 mgNO₃- N/l and 20 to 30 mgPO₄-P/l) that can be returned to the activated sludge plant without overloading it. DA - 2015 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2015 T1 - The removal of nitrogen and phosphorus in anoxic-aerobic digestion of waste activated sludge from biological nutrient removal systems TI - The removal of nitrogen and phosphorus in anoxic-aerobic digestion of waste activated sludge from biological nutrient removal systems UR - http://hdl.handle.net/11427/24307 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/24307
dc.identifier.vancouvercitationVogts M. The removal of nitrogen and phosphorus in anoxic-aerobic digestion of waste activated sludge from biological nutrient removal systems. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Water Research Group, 2015 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/24307en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentWater Research Groupen_ZA
dc.publisher.facultyFaculty of Engineering and the Built Environment
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherCivil Engineeringen_ZA
dc.subject.otherWater Researchen_ZA
dc.titleThe removal of nitrogen and phosphorus in anoxic-aerobic digestion of waste activated sludge from biological nutrient removal systemsen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMSc (Eng)en_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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