IWA Publishing
 IWA Publishing Journals   Subscriptions   Authors   Users   Librarians   FAQs 

Water Science & Technology Vol 50 No 10 pp 171–180 © IWA Publishing 2004

Optimisation of storage driven denitrification by using on-line specific oxygen uptake rate monitoring during SND in a SBR

K.A. Third*, S. Sepramaniam**, Z. Tonkovic***, M. Newland**** and R. Cord-Ruwisch*****

*School of Biological Sciences and Biotechnology, Murdoch University, South Street, Murdoch, Western Australia 6150, Australia (E-mail: cord@murdoch.edu.au)
**School of Biological Sciences and Biotechnology, Murdoch University, South Street, Murdoch, Western Australia 6150, Australia (E-mail: cord@murdoch.edu.au)
***Environmental Solutions International Ltd. (ESI), 21 Teddington Rd, Burswood, Western Australia 6100, Australia
****Environmental Solutions International Ltd. (ESI), 21 Teddington Rd, Burswood, Western Australia 6100, Australia
*****School of Biological Sciences and Biotechnology, Murdoch University, South Street, Murdoch, Western Australia 6150, Australia (E-mail: cord@murdoch.edu.au)


ABSTRACT
This study builds on previous experience of maximising the formation of COD as poly-hydroxybutyrate (PHB) and now describes a feedback technique of preserving the use of PHB for denitrification resulting in enhanced nitrogen removal rather than allowing its wasteful oxidation by oxygen. The feedback technique uses on-line SOUR monitoring for detecting the end-point of nitrification and controlling the aerobic phase length accordingly. The laboratory SBR was operated such that all organic substrate (acetate) was rapidly converted to PHB, which then served as the electron donor for nitrogen removal via simultaneous nitrification and denitrification (SND) during the aerobic phase (up to 70% SND). During SBR cycling with a fixed aeration length (240 minutes), PHB was unnecessarily oxidised after ammonium depletion, resulting in little denitrification and poor total nitrogen removal (69%). However, when the aerobic phase length was controlled via the SOUR, up to 1.8 CmM PHB (58 mg L–1 COD) could be preserved, enabling improved total nitrogen removal (86%). The drop in the SOUR after ammonium depletion was a reproducible event that could be detected even when using raw wastewater and fresh activated sludge. The SOUR-control technique holds promise to build up PHB over a number of SBR cycles. While advanced oxygen-control is used for improved N-removal in several existing WWTPs, this study investigates the importance of oxygen control with relevance to PHB driven SND in sequencing batch reactors.

Full article (PDF Format)


eProduct: Buy this article for £24.00 (IWA MEMBER PRICE: £18.00)
All prices include VAT. For customers where VAT should not be applied, the VAT amount will be removed upon payment