Effect of exogenous carbon sources on removal of inorganic nutrient by the nitrification-denitrification process

Tam, N.F.Y.; Wong, Yuk Shan; Leung, Gina

doi:10.1016/0043-1354(92)90183-5

Cited by 75 publications

(33 citation statements)

References 16 publications

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“…Methanol is the most commonly employed external carbon source due to being easily assimilated by denitrifying bacteria and its low cost [10,11,12,13,14]. Ethanol and acetic acid constitute other equivalent commercial sources [5,15,16].…”

Section: Introductionmentioning

confidence: 99%

Denitrification of high nitrate concentration wastewater using alternative carbon sources

Fernández-Nava

Marañón

Soons

et al. 2010

Journal of Hazardous Materials

201

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The use of different organic carbon sources in the denitrification of wastewater containing 2500 mg nitrates/L in a SBR was studied. Three alternative sources of carbon were tested: wastewater from a sweet factory, a residue from a soft drinks factory and a residue from a dairy plant. The first two are sugar rich, whereas the third presents a high content in lactic acid. Maximum specific denitrification rates of between 42 and 48 mg NO 3 -N/g VSS·h were obtained. The effluents were nitrate free and very low COD concentrations were obtained in 4-6 hours reaction time, especially with the sugar-rich carbon sources. The values of the denitrifier net yield coefficient were higher than when using methanol (0.93-1.75 g VSS formed /g NOx-N reduced ). The lowest value was obtained using the lactic acid-rich residue. The optimum COD/N ratios varied between 4.6 for the lactic acid-rich carbon source and 5.5 -6.5 for the sugar-rich carbon sources.

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Section: Introductionmentioning

confidence: 99%

Denitrification of high nitrate concentration wastewater using alternative carbon sources

Fernández-Nava

Marañón

Soons

et al. 2010

Journal of Hazardous Materials

201

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“…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).…”

mentioning

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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“…This reduces the amount of substrate available for PAOs, and hence causes the reduction of phosphorus release [20,21]. If influent contains significant amounts of fermented product such as acetate, both denitrification and phosphorus release take place simultaneously [22], whereas for less presence of fermented substrate, phosphorus release takes place after exhausting nitrate [19]. As stated above, the influent used in this study may have relatively insufficient amount of readily biodegradable organic substrate.…”

Section: Resultsmentioning

confidence: 96%

Effects of internal recycling time mode and hydraulic retention time on biological nitrogen and phosphorus removal in a sequencing anoxic/anaerobic membrane bioreactor process

Song

Cho

Ahn

2008

Bioprocess Biosyst Eng

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This study investigated the effects of internal recycling time mode and hydraulic retention time (HRT) on nutrient removal in the sequencing anoxic/anaerobic membrane bioreactor process. Denitrification and phosphorus release were reciprocally dependent on the anoxic/anaerobic time ratio (Ax/An). As Ax/An increased, nitrogen removal rate increased but phosphorus removal rate decreased. The increasing Ax/An provided the longer denitrification period so that the organic substrate were consumed more for denitrification rather than phosphorus release in the limited condition of readily biodegradable substrate. Decreasing HRT increased both nitrogen and phosphorus removal efficiency because as HRT decreased, food-to-microorganism loading ratio increased and thus enhanced the biological capacity and activity of denitrifying bacteria. This could be verified from the observation mixed liquor suspended solids concentration and specific denitrification rate. The change of Ax/An and HRT affected phosphorus removal more than nitrogen removal due to the limitation of favourable carbon source for phosphorus accumulating organisms.

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Effect of exogenous carbon sources on removal of inorganic nutrient by the nitrification-denitrification process

Cited by 75 publications

References 16 publications

Denitrification of high nitrate concentration wastewater using alternative carbon sources

Denitrification of high nitrate concentration wastewater using alternative carbon sources

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

Effects of internal recycling time mode and hydraulic retention time on biological nitrogen and phosphorus removal in a sequencing anoxic/anaerobic membrane bioreactor process

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