Modeling urea biodegradation in activated sludge using combined respirometric-titrimetric measurements

Hoque, Muhammad Azizul and Aravinthan, Vasantha (2011) Modeling urea biodegradation in activated sludge using combined respirometric-titrimetric measurements. Desalination and Water Treatment, 32 (1-3). pp. 115-125. ISSN 1944-3994

Abstract

Urea biodegradation kinetics determination has been performed in the literature using a two-step nitrification model that was calibrated using on-line respirometric measurements. However, the model neglected the initial hydrolysis step that converts urea to carbon dioxide and ammonia nitrogen, and assumed constant carbon dioxide transfer rate (CTR), though it is inherently a nonlinear process which has an impact on the titrimetric modeling. Hence, in this paper, it is aimed to propose a complete two-step nitrification model for urea biodegradation paying attention to urea degradation pathway along with due consideration given for non-linear CTR process occurring in activated sludge system. Experiments were performed in a simple batch reactor equipped with respirometric and titrimetric set-up. Three different initial urea concentrations were added to the reactor for investigating the process kinetics. Proposed model was successfully calibrated with respirometric, titrimetric and combined respirometric–titrimetric measurements; and the estimated parameters were compared for model evaluation. Furthermore, the proposed model was validated with off-line ammonium, nitrite and nitrate measurements. The study revealed that urea was hydrolyzed at a faster rate in liquid phase. The maximum growth rates of the Nitrosomonas species and the Nitrobacter species were found to be 0.065–0.1 d–1 and 0.006–0.008 d–1 respectively.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Copyright will be retained by authors who may place their papers on their personal or institutional websites.
Depositing User: Dr Vasantha Aravinthan
Faculty / Department / School: Historic - Faculty of Engineering and Surveying - Department of Agricultural, Civil and Environmental Engineering
Date Deposited: 04 May 2011 23:59
Last Modified: 25 Nov 2013 01:33
Uncontrolled Keywords: oxygen uptake rate (OUR); urea biodegradation; model calibration; nitrification
Fields of Research (FOR2008): 09 Engineering > 0907 Environmental Engineering > 090702 Environmental Engineering Modelling
10 Technology > 1002 Environmental Biotechnology > 100203 Bioremediation
09 Engineering > 0904 Chemical Engineering > 090409 Wastewater Treatment Processes
Socio-Economic Objective (SEO2008): B Economic Development > 90 Commercial Services and Tourism > 9004 Water and Waste Services > 900499 Water and Waste Services not elsewhere classified
D Environment > 96 Environment > 9699 Other Environment > 969999 Environment not elsewhere classified
Identification Number or DOI: doi: 10.5004/dwt.2011.2686
URI: http://eprints.usq.edu.au/id/eprint/19008

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