Kinetic characterization of a low-dissolved-oxygen oxic-anoxic process treating low COD/N tropical wastewater revealed selection of nitrifiers with high substrate affinity
Document Type
Article
Publication Date
10-1-2021
Abstract
The design of wastewater treatment plants in the tropics is largely based on default parameters from the studies in temperate climates. This may lead to suboptimal design, such as the intensive aeration required for biological nitrogen removal. To reduce the aeration energy, a low-dissolved-oxygen oxic-anoxic (low-DO OA) process was developed for treating low chemical oxygen demand-to-nitrogen (COD/N) tropical wastewater. This study calibrated the growth kinetic parameters of microbes in a conventional anoxic-oxic (AO) and a low-DO OA sequencing batch reactors (SBRs) based on a modified version of Activated Sludge Model No. 1 (ASM1). We selected three parameters to be calibrated, namely the maximum growth rate of heterotrophs (mu(H)), maximum growth rate of nitrifiers (mu(A)) and nitrifiers' affinity towards ammoniacal nitrogen (NH4+ -N) (KNH). The low-DO OA SBR selected for microbes with a low mu(H) (2.2 d(-1)), mu A (1.49 d-1) and KNH (0.035 mg NH4+ -N L-1), which supported the observed proliferation of K-strategist Nitrospira at low-DO condition (0.4 +/- 0.2 mg O-2 L-1). The calibrated parameters for the AO SBR (1.7 +/- 0.2 mg O-2 L-1) were significantly higher (mu H=9.3 d(-1), mu A=4.49 d(-1), KNH=6.3 mg NH4+ -N L-1) than the low-DO OA SBR. The calibrated ASM1 adequately simulated the low-DO OA SBR performance under different sludge retention times. The findings demonstrated a kinetic insight into the unique K-strategist nitrifiers in a low-DO OA process. Moreover, this study reinforced the importance of using parameters for tropical wastewater rather than relying on default values from studies in temperate climates.
Keywords
Activated sludge model, Calibration, Maximum growth rate, Nitrification, Nitrospira
Divisions
sch_che
Funders
Newton Fund Impact Scheme (NFIS) grant under the Newton-Ungku Omar Fund (536710788/IF024-2020),Malaysian Industry-Government Group for High Technology (MIGHT),UK UK Department for Business, Energy and Industrial Strategy,Research University Faculty Program Grant by the Ministry of Higher Education Malaysia (GPF024A-2019)
Publication Title
Journal of Water Process Engineering
Volume
43
Publisher
Elsevier
Publisher Location
RADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS