Rate-Capacity Characterization of Wastewater for Nutrient Removal Processes

Henze, Mogens; Kristensen, Gert Holm; Strube, Rune

doi:10.2166/wst.1994.0318

Cited by 85 publications

(42 citation statements)

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“…Maximum denitrification rate is comparable with the literature value (0.05 day -1 ) reported by Henze et al (1994) when an endogenous carbon source is used (as in this case). Other parameters for both nitrification and denitrification are comparable with the literature values except K O2 whose higher value (i.e.…”

Section: Modelling-nitrogen Fatesupporting

confidence: 90%

Post-aerobic digestion of waste sludge: performance analysis and modelling of nitrogen fate under alternating aeration

Tomei

Carozza

Angelucci

2015

Int. J. Environ. Sci. Technol.

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Combined anaerobic-aerobic sludge digestion has been demonstrated as a valid technological solution to improve the sludge stabilization process, in terms of solid reduction and sludge dewaterability properties. In this study, we investigated the fate of all nitrogen species (ammonia, nitrites, nitrates) in the sequential digestion process when the post-aerobic step is operated with intermittent aeration. Nitrogen course has been followed in the two digesters operated in semi-continuous mode and in batch nitrification-denitrification kinetic tests. Two-stage digestion was applied to real waste activated sludge. High volatile solid removal efficiencies (47 and 26 % in the anaerobic and aerobic phases, respectively) confirmed the potential of this technology. Moreover, the post-aerobic stage allowed to successfully achieving nitrogen removal through the simultaneous nitrification-denitrification process. Nitrification and denitrification efficiencies were 95 and 70 %, respectively. Batch tests for nitrification and denitrification were also carried out to investigate the process kinetics. A process model has been formulated and calibrated with a first set of experimental kinetic data. Evaluated kinetic parameters were employed in the validation phase successfully performed (correlation coefficients R 2 [ 0.98) with different series of experimental data.

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Section: Modelling-nitrogen Fatesupporting

confidence: 90%

Post-aerobic digestion of waste sludge: performance analysis and modelling of nitrogen fate under alternating aeration

Tomei

Carozza

Angelucci

2015

Int. J. Environ. Sci. Technol.

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“…All through the experiment, 15 mg/L nitrite formed and accumulated in the medium, corresponding to an NO2 -N/NO3 -Ninitial ratio of about 23%. The observed nitrite accumulation can be attributed to substrate limitation [18,34] because the initial COD/NO 3 --N ratio was 2.3, which is reasonably less than the theoretically expected value of 2.86 for complete denitrification as well as experimentally determined values (3.5 -4.5 g COD/g N) [19].…”

Section: Nur Tests For Different Enrichment Cultures Under Substrate-mentioning

confidence: 55%

“…If no growth occurs, this ratio would be 2.86 kg substrate chemical oxygen demand (COD)/kg N, which can be considered as the theoretical minimum. However, this ratio will normally be about 3.5 to 4.5 g COD/g N for complete denitrification, considering bacterial growth [19]. Even higher rates are reported in wastewater treatment plants [20].…”

Section: Introductionmentioning

confidence: 96%

Effects of Different Carbon Sources on Denitrification Efficiency Associated with Culture Adaptation and C/N Ratio

Güven¹

2009

CLEAN Soil Air Water

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Stringent effluent limitations for nitrogen necessitate an accurate interpretation of the design and operation conditions of biological nitrogen removal systems. In this study, the effects of the nature of the organic substrate on biomass adaptation and response to different C/N ratios in terms of denitrification efficiency were investigated. A relatively high chemical oxygen demand (COD) utilized /NO x -N reduced ratio of 8.1 was obtained when an excess amount of readily biodegradable carbon was supplied, which is suggested as the conversion of substrate surplus into storage polymers. An anoxic yield of 0.64 g cell COD/g COD for a four-compound substrate mixture (acetate, propionate, ethanol and glucose), 0.63 g cell COD/g COD for a two-compound substrate mixture (acetate and propionate), and 0.5 g cell COD/g COD for methanol were calculated. Fluorescence in situ hybridization analysis showed that the b-subclass of proteobacteria was dominant in the seed and in cultures adapted to both the fourcompound and the two-compound substrate mixture, whereas in the methanoladapted culture significant amounts of b-proteobacteria were detected. The biocommunity composition, the type of organic compound and the COD/NO 3 -N ratio strongly influence the nitrate reduction and carbon utilization profiles. Methanol has been shown to select for a denitrifying population consisting of Paracoccus and Hyphomicrobium vulgare genera, when used as only external carbon source.

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“…A reduced capacity to denitrify with fatty acids can be a negative development in predenitrification processes, since it reflects a lower potential to exploit the substances naturally occurring in wastewater. Volatile fatty acids represent the major fraction of easily degradable COD in wastewater, and acetate probably accounts for 5 to 10% of the total COD (15). The addition of either ethanol or methanol as an external carbon source enhanced the denitrification capacity with primary alcohols.…”

Section: Discussionmentioning

confidence: 99%

Metabolic Profiles and Genetic Diversity of Denitrifying Communities in Activated Sludge after Addition of Methanol or Ethanol

Hallin

Throbäck

Dicksved

et al. 2006

Appl Environ Microbiol

102

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External carbon sources can enhance denitrification rates and thus improve nitrogen removal in wastewater treatment plants. The effects of adding methanol and ethanol on the genetic and metabolic diversity of denitrifying communities in activated sludge were compared using a pilot-scale plant with two parallel lines. A full-scale plant receiving the same municipal wastewater, but without external carbon source addition, was the reference. Metabolic profiles obtained from potential denitrification rates with 10 electron donors showed that the denitrifying communities altered their preferences for certain compounds after supplementation with methanol or ethanol and that methanol had the greater impact. Clone libraries of nirK and nirS genes, encoding the two different nitrite reductases in denitrifiers, revealed that methanol also increased the diversity of denitrifiers of the nirS type, which indicates that denitrifiers favored by methanol were on the rise in the community. This suggests that there might be a niche differentiation between nirS and nirK genotypes during activated sludge processes. The composition of nirS genotypes also varied greatly among all samples, whereas the nirK communities were more stable. The latter was confirmed by denaturing gradient gel electrophoresis of nirK communities on all sampling occasions. Our results support earlier hypotheses that the compositions of denitrifier communities change during predenitrification processes when external carbon sources are added, although no severe effect could be observed from an operational point of view.Considerable efforts have been made to improve the technology for efficient and economic removal of nitrogen by denitrification in municipal activated sludge. Denitrification is an anaerobic microbial respiration process with a stepwise reduction of nitrate or nitrite via nitric oxide to nitrous oxide or dinitrogen. In the ideal activated sludge process, bacteria denitrify by using carbon compounds in the influent wastewater as electron donors. As a means to improve control strategies for nitrogen removal, external carbon compounds can be added to enhance denitrification rates (10,14,18,19,34,35). Higher rates allow reductions in the hydraulic retention time in the anoxic zones, making it possible to minimize basin volumes (23). For this purpose, methanol and ethanol are most commonly used in practice, although acetate has been reported to give the highest rates in most cases (12,24,(28)(29)(30).Although much is known about process performance after the addition of external carbon sources, little effort has been made to explain the specific effects on the denitrifying communities in activated sludge. The selective pressure from the carbon compound added might affect the composition of the denitrifying community, which would influence metabolic diversity and functional properties of the denitrifiers. For example, it was shown that acetate as the major carbon source in a laboratory-scale reactor selected for denitrifiers with nonflocculating proper...

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Rate-Capacity Characterization of Wastewater for Nutrient Removal Processes

Cited by 85 publications

References 0 publications

Post-aerobic digestion of waste sludge: performance analysis and modelling of nitrogen fate under alternating aeration

Post-aerobic digestion of waste sludge: performance analysis and modelling of nitrogen fate under alternating aeration

Effects of Different Carbon Sources on Denitrification Efficiency Associated with Culture Adaptation and C/N Ratio

Metabolic Profiles and Genetic Diversity of Denitrifying Communities in Activated Sludge after Addition of Methanol or Ethanol

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