Aerobic Denitrification Studies on Activated Sludge Mixed with Thiosphaera Pantotropha

Kshirsagar, Mona; Gupta, Asmita; Gupta, S. K.

doi:10.1080/09593331608616243

Cited by 32 publications

(12 citation statements)

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“…This finding suggests that the isolates could be maintained in the mixed population of microorganisms found in sludge as is observed with P. denitrificans, which reduces NO 3 Ϫ more efficiently than a control reactor without the strain when it is mixed with activated sludge (9). Sometimes, a C 1 carbon source, such as methanol or formate, has been used to manipulate the dominant bacterial species in sludge (5,21).…”

Section: Discussionmentioning

confidence: 96%

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Aerobic Denitrifying Bacteria That Produce Low Levels of Nitrous Oxide

Takaya

Catalan-Sakairi

Sakaguchi

et al. 2003

Appl Environ Microbiol

278

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Most denitrifiers produce nitrous oxide (N 2 O) instead of dinitrogen (N 2 ) under aerobic conditions. We isolated and characterized novel aerobic denitrifiers that produce low levels of N 2 O under aerobic conditions. We monitored the denitrification activities of two of the isolates, strains TR2 and K50, in batch and continuous cultures. Both strains reduced nitrate (NO 3 ؊ ) to N 2 at rates of 0.9 and 0.03 mol min ؊1 unit of optical density at 540 nm ؊1 at dissolved oxygen (O 2 ) (DO) concentrations of 39 and 38 mol liter ؊1 , respectively. At the same DO level, the typical denitrifier Pseudomonas stutzeri and the previously described aerobic denitrifier Paracoccus denitrificans did not produce N 2 but evolved more than 10-fold more N 2 O than strains TR2 and K50 evolved. The isolates denitrified NO 3؊ with concomitant consumption of O 2 . These results indicated that strains TR2 and K50 are aerobic denitrifiers. These two isolates were taxonomically placed in the ␤ subclass of the class Proteobacteria and were identified as P. stutzeri TR2 and Pseudomonas sp. strain K50. These strains should be useful for future investigations of the mechanisms of denitrifying bacteria that regulate N 2 O emission, the single-stage process for nitrogen removal, and microbial N 2 O emission into the ecosystem.Nitrous oxide (N 2 O) is a gaseous nitrogen oxide that is present at a concentration of about 350 ppb in the atmosphere. The concentration of this compound was maintained below 300 ppb in the global nitrogen cycle before the 20th century. However, recent reports suggest that the atmospheric concentration of N 2 O is now increasing at a rate as high as 0.3% per year (1). N 2 O has a 200-to 300-fold-stronger greenhouse effect than carbon dioxide (CO 2 ) and has the potential to destroy the ozone layer (17). Therefore, the N 2 O balance is critical to the natural environment. The proposed sources of N 2 O are chemical industries, burning fossil fuels, and biomass, as well as soil denitrification of nitrogenous compounds resulting from excess agricultural fertilizer (3,6,25). Another critical source of N 2 O is wastewater treatment plants, in which considerable amounts of nitrogen pollutants removed from treated water are released into the atmosphere as N 2 O, as well as dinitrogen (N 2 ).Currently, nitrogen removal in wastewater treatment plants is essentially based on the activity of nitrifying and denitrifying microorganisms, both of which are inhabitants of activated sludge. Nitrifying bacteria aerobically oxidize ammonium contaminants to nitrite (NO 2 Ϫ ) and nitrate (NO 3 Ϫ ), which are then reduced by denitrifying bacteria to gaseous nitrogen forms such as N 2 O and N 2 . Efficient wastewater treatment relies on successively exposing water to aerobic and anaerobic conditions, since nitrification and denitrification are aerobic and anaerobic processes, respectively (4, 18). These properties represent a shortcoming of current systems since both denitrification and nitrification produce N 2 O as a by-product in the absen...

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Section: Discussionmentioning

confidence: 96%

“…Nitric oxide reductase (Nor) activity was determined by determining NADH-dependent N 2 O formation by GC as described previously (11). Nitrous oxide reductase activity was assayed as described by Kshirsagar et al (9).…”

Section: Strainsmentioning

confidence: 99%

Aerobic Denitrifying Bacteria That Produce Low Levels of Nitrous Oxide

Takaya

Catalan-Sakairi

Sakaguchi

et al. 2003

Appl Environ Microbiol

278

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“…Denitrification gene expression occurs under anoxic or aerobic conditions and requires the presence of an N-oxide. [5] Large numbers of denitrifying bacteria have been isolated from activated sludge and soil including [6][7][8][9][10][11][12][13] [14][15][16][17][18] There were many recent reports of aerobic denitrifying species such as Alcaligenes faecalis, [18] Citrobacter diversus, [9] Pseudomonas aeruginosa, [19] Pseudomonas stutzeri, [12] and Thiosphaera pantotropha, [12] which were isolated from canals, ponds, soils, and activated sludge. In this work, pure cultures of Pseudomonas sp.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of nitrate removal in a bio-ceramsite reactor by aerobic denitrification

Chen

Yang

et al. 2014

Environmental Technology

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A newly aerobic denitrifying bacterial strain, Pseudomonas sp. X31, which was isolated from activated sludge, was added to a newly developed aerobic denitrification bio-ceramsite reactor as an inoculum to treat nitrate-polluted water and the denitrification activities of this system under different air-water ratio, hydraulic loading, and C/N (carbon/nitrogen ratio) conditions were investigated. It demonstrated excellent capability for denitrification in the bio-ceramsite reactor at air-water ratios that varied from 6.5:1 to 8:1. The optimal hydraulic loading for the bio-ceramsite reactor was 0.75 m/h with the optimum denitrification efficiency of 95.18%. The optimal C/N was 4.5:1 with a maximum nitrate removal efficiency of 98.48%. COD could be completely removed under the most appropriate condition (air-water ratio 6.5:1-8:1, hydraulic loading 0.75 m/h, and C/N 4.5:1). The quantity of the biomass in the reactor decreased along with flow, which was in accordance with the variety of the available substrate concentrations in the water. However, the biofilm activity was not proportional to the biomass in the bio-ceramsite reactor, but increased with the quantity of the biomass up to a peak value and then decreased.

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“…Some studies have explored nitrogen removal in presence of such strains for low-strength wastewater having NH 4 + -N in the range 20-200 mg L −1 (Gupta and Gupta 1999;Pochana and Keller 1999;Lee et al 2001;Li et al 2007;Zhang andZhou 2007, Morita et al, 2008;Singh and Mittal, 2013) and also wastewater containing nitrophenols in the range 2.5-200 mg L −1 (Kulkarni, 2012;Kulkarni, 2013). However, there are only limited studies on application of such strains for nitrogen removal from highstrength wastewater (Kshirsagar et al 1995;Gupta and Gupta 2001;Joo et al 2005;Joo et al 2006). None of the studies employing high-strength wastewater in presence of strains capable of SND have been performed in sequencing batch reactors (SBRs) that are shown to have good potential for promoting nutrient removal through granulation.…”

Section: Introductionmentioning

confidence: 97%

Start-up of sequencing batch reactor with Thiosphaera pantotropha for treatment of high-strength nitrogenous wastewater and sludge characterization

Phatak

Trivedi

Garg

et al. 2016

Environ Sci Pollut Res

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Biological treatment of high-strength nitrogenous wastewater is challenging due to low growth rate of autotrophic nitrifiers. This study reports bioaugmentation of Thiosphaera pantotropha capable of simultaneously performing heterotrophic nitrification and aerobic denitrification (SND) in sequencing batch reactors (SBRs). SBRs fed with 1:1 organic-nitrogen (N) and NH-N were started up with activated sludge and T. pantotropha by gradual increase in N concentration. Sludge bulking problems initially observed could be overcome through improved aeration and mixing and change in carbon source. N removal decreased with increase in initial nitrogen concentration, and only 50-60 % removal could be achieved at the highest N concentration of 1000 mg L at 12-h cycle time. SND accounted for 28 % nitrogen loss. Reducing the settling time to 5-10 min and addition of divalent metal ions gradually improved the settling characteristics of sludge. Sludge aggregates of 0.05-0.2 mm diameter, much smaller than typical aerobic granules, were formed and progressive increase in settling velocity, specific gravity, Ca, Mg, protein, and polysaccharides was observed over time. Granulation facilitated total nitrogen (TN) removal at a constant rate over the entire 12-h cycle and thus increased TN removal up to 70 %. Concentrations of NO-N and NO-N were consistently low indicating effective denitrification. Nitrogen removal was possibly limited by urea hydrolysis/nitrification. Presence of T. pantotropha in the SBRs was confirmed through biochemical tests and 16S rDNA analysis.

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Aerobic Denitrification Studies on Activated Sludge Mixed with Thiosphaera Pantotropha

Cited by 32 publications

References 0 publications

Aerobic Denitrifying Bacteria That Produce Low Levels of Nitrous Oxide

Aerobic Denitrifying Bacteria That Produce Low Levels of Nitrous Oxide

Characteristics of nitrate removal in a bio-ceramsite reactor by aerobic denitrification

Start-up of sequencing batch reactor with Thiosphaera pantotropha for treatment of high-strength nitrogenous wastewater and sludge characterization

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