Investigation of the Effects of COD/TP Ratio on the Performance of a Biological Nutrient Removal System

dc.contributor.authorPunrattanasin, Warangkanaen
dc.contributor.committeechairRandall, Clifford W.en
dc.contributor.committeememberBoardman, Gregory D.en
dc.contributor.committeememberLove, Nancy G.en
dc.contributor.departmentEnvironmental Sciences and Engineeringen
dc.date.accessioned2014-03-14T20:51:54Zen
dc.date.adate1997-04-23en
dc.date.available2014-03-14T20:51:54Zen
dc.date.issued1997-04-23en
dc.date.rdate1997-04-23en
dc.date.sdate1998-07-21en
dc.description.abstractThe laboratory-scale University of Cape Town (UCT) process was designed to investigate the effects of changing COD/TP ratios on the performance of biological nutrient removal (BNR) processes. Specific objectives of the research were to investigate the effects of COD/TP ratio on the rates of phosphorus removal, COD removal, nitrogen removal, PHB utilization and oxygen uptake. The system was fed with municipal wastewater and operated at 20° C. The influent COD concentration was held approximately constant while the phosphorus concentration was varied to obtained the desired COD/TP ratio. Once robust enhanced biological phosphorus removal (EBPR) has been established, the COD/TP ratios of 20, 30, 40 and 60 were investigated. The COD/TP ratio of the influent wastewater was observed to have a substantial effect upon the performance of the UCT BNR system. The amount of phosphorus removed by the system and the percent phosphorus in the aerobic zone MLVSS decreased as the COD/TP ratio increased. In addition, the amount of phosphorus released in the anaerobic zone per unit of COD removed in the anaerobic zone increased as the COD/TP ratio decreased. From this research, the amount of anaerobic COD removal required to remove 1 mg/L of phosphorus in the aerobic zone approached a minimum value as the COD/TP ratio decreased. It was also shown that PHB production increased as the COD/TP ratio increased. The highest specific oxygen uptake rate was always observed in the second aerobic reactor and tended to increase as the COD/TP ratio increased. However, the changes in the COD/TP ratio did not significant affect COD removal, nitrogen removal and the observed yield coefficient, but did strongly affect the MLSS concentration. The MLSS concentration at the COD/TP ratio of 60 was only 55% of that at the COD/TP ratio of 20. A high level of anaerobic COD removal, an elevated percent phosphorus in the waste activated sludge (WAS) and a high soluble effluent phosphorus concentration can be used as indicators that the system is operating under COD limiting conditions. Several phenomena were also observed during this research. Firstly, the performance of the UCT BNR system for EBPR was greatly enhanced by reducing the aerobic volume. Secondly, the correlation between non-oxic phosphorus release and the aerobic phosphorus uptake improved when anoxic phosphorus release was taking into consideration. This indicated that the anoxic phosphorus release was not secondary release once the aerobic zone volume was reduced. Finally, no denitrification was observed in the aerobic zone from this study, based on the assumption that 12% of nitrogen was required for bacterial growth.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-5818192749721461en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-5818192749721461/en
dc.identifier.urihttp://hdl.handle.net/10919/36819en
dc.publisherVirginia Techen
dc.relation.haspartetd.PDFen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectCOD/TP ratioen
dc.subjectbiological nutrient removalen
dc.subjectbiological phosphorus removalen
dc.subjectphosphorus uptakeen
dc.subjectphosphorus releaseen
dc.titleInvestigation of the Effects of COD/TP Ratio on the Performance of a Biological Nutrient Removal Systemen
dc.typeThesisen
thesis.degree.disciplineEnvironmental Sciences and Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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