Effect of pH on N2O reduction and accumulation during denitrification by methanol utilizing denitrifiers

Pan, Yuting, Ye, Liu, Ni, Bing-Jie and Yuan, Zhiguo (2012) Effect of pH on N2O reduction and accumulation during denitrification by methanol utilizing denitrifiers. Water Research, 46 15: 4832-4840. doi:10.1016/j.watres.2012.06.003

Author Pan, Yuting
Ye, Liu
Ni, Bing-Jie
Yuan, Zhiguo
Title Effect of pH on N2O reduction and accumulation during denitrification by methanol utilizing denitrifiers
Formatted title
Effect of pH on N2O reduction and accumulation during denitrification by methanol utilizing denitrifiers
Journal name Water Research   Check publisher's open access policy
ISSN 0043-1354
Publication date 2012-10-01
Year available 2012
Sub-type Article (original research)
DOI 10.1016/j.watres.2012.06.003
Open Access Status Not Open Access
Volume 46
Issue 15
Start page 4832
End page 4840
Total pages 9
Place of publication Hoboken, NJ, United States
Publisher Wiley-Blackwell Publishing
Language eng
Subject 2312 Water Science and Technology
2311 Waste Management and Disposal
2310 Pollution
2302 Ecological Modelling
Abstract This paper presents a systematic investigation into monomer development during mixed culture Polyhydroxyalkanoates (PHA) accumulation involving concurrent active biomass growth and polymer storage. A series of mixed culture PHA accumulation experiments, using several different substrate-feeding strategies, was carried out. The feedstock comprised volatile fatty acids, which were applied as single carbon sources, as mixtures, or in series, using a fed-batch feed-on-demand controlled bioprocess. A dynamic trend in active biomass growth as well as polymer composition was observed. The observations were consistent over replicate accumulations. Metabolic flux analysis (MFA) was used to investigate metabolic activity through time. It was concluded that carbon flux, and consequently copolymer composition, could be linked with how reducing equivalents are generated.
Formatted abstract
Acidic pH has previously been found to increase nitrous oxide (N2O) accumulation during heterotrophic denitrification in biological wastewater treatment. However, the mechanism of this phenomenon still needs to be clarified. By using an enriched methanol utilizing denitrifying culture as an example, this paper presents a comprehensive study on the effect of pH (6.0–9.0) on N2O reduction kinetics with N2O as the sole electron acceptor, as well as the effect of pH on N2O accumulation with N2O as an intermediate of nitrate reduction. The pH dependency of nitrate and nitrite reduction was also investigated. The maximum biomass-specific N2O reduction rate is higher than the corresponding maximum nitrate and nitrite reduction rates in the entire pH range studied. However, the maximum biomass-specific N2O reduction rate is much more sensitive to pH variation outside of the optimal range (pH 7.5 to pH 8.0) than the maximum biomass-specific nitrate and nitrite reduction rates. The half-saturation coefficient of the N2O reductase increased from 0.10 mg N2O-N/L to 0.92 mg N2O-N/L as pH increased from pH 6.0 to 9.0. At pH 6.0, approximately 20% and 40% of the denitrified nitrate accumulated as N2O in the presence and absence of methanol (as an exogenous carbon source), respectively. However, at pH 6.5, these fractions decreased to 0% and 30%, respectively. No N2O accumulation occurred at pH 7.0 to 9.0 independent of the availability of methanol. These results suggest that the competition for electrons among different nitrogen oxides reductases likely plays a role in N2O accumulation at low pH conditions.
Keyword Nitrous oxide
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID LP0991765
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2013 Collection
Advanced Water Management Centre Publications
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