Nitrate and nitrite reduction activity of activated sludge microcosm in a highly alkaline environment with solid cementitious material

ABSTRACTNitrate reduction to nitrite in oil fields appears to be more thermophilic than the subsequent reduction of nitrite. Concentrated microbial consortia from oil fields reduced both nitrate and nitrite at 40 and 45°C but only nitrate at and above 50°C. The abundance of thenirSgene correlated with mesophilic nitrite reduction activity.ThaueraandPseudomonaswere the dominant mesophilic nitrate-reducing bacteria (mNRB), whereasPetrobacterandGeobacilluswere the dominant thermophilic NRB (tNRB) in these consortia. The mNRBThauerasp. strain TK001, isolated in this study, reduced nitrate and nitrite at 40 and 45°C but not at 50°C, whereas the tNRBPetrobactersp. strain TK002 andGeobacillussp. strain TK003 reduced nitrate to nitrite but did not reduce nitrite further from 50 to 70°C. Testing of 12 deposited pure cultures of tNRB with 4 electron donors indicated reduction of nitrate in 40 of 48 and reduction of nitrite in only 9 of 48 incubations. Nitrate is injected into high-temperature oil fields to prevent sulfide formation (souring) by sulfate-reducing bacteria (SRB), which are strongly inhibited by nitrite. Injection of cold seawater to produce oil creates mesothermic zones. Our results suggest that preventing the temperature of these zones from dropping below 50°C will limit the reduction of nitrite, allowing more effective souring control.IMPORTANCENitrite can accumulate at temperatures of 50 to 70°C, because nitrate reduction extends to higher temperatures than the subsequent reduction of nitrite. This is important for understanding the fundamentals of thermophilicity and for the control of souring in oil fields catalyzed by SRB, which are strongly inhibited by nitrite.

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Dissimilatory Nitrate and Nitrite Reduction under Aerobic Conditions by an Aerobically and Anaerobically GrownAlcaligenessp. and by Activated Sludge

Journal of Applied Bacteriology ◽

10.1111/j.1365-2672.1976.tb04172.x ◽

1976 ◽

Vol 40 (3) ◽

pp. 245-260 ◽

Cited By ~ 25

Author(s):

J. M. KRUL

Keyword(s):

Activated Sludge ◽

Nitrite Reduction ◽

Aerobic Conditions ◽

Nitrate And Nitrite

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Assessment of denitrification by the ordinary heterotrophic organisms in an NDBEPR activated sludge sytem

Water Science & Technology ◽

10.2166/wst.2001.0036 ◽

2001 ◽

Vol 43 (1) ◽

pp. 147-154 ◽

Cited By ~ 24

Author(s):

G. D. Drysdale ◽

H. C. Kasan ◽

F. Bux

Keyword(s):

Activated Sludge ◽

Functional Groups ◽

Heterotrophic Bacteria ◽

Nitrite Reduction ◽

Accurate Evaluation ◽

Anoxic Conditions ◽

Nitrate And Nitrite ◽

Anoxic Zones

The purpose of this study was to isolate and characterise the ordinary heterotrophic organisms (OHOs) present in a NDBEPR system in order to gain a better understanding of the organisms involved in denitrification as well as a more holistic and accurate evaluation of the OHO fraction attributable to denitrification in such a system. Heterotrophic bacteria were isolated from the pre- and secondary anoxic zones of the Darvill NDBEPR process and characterised according to their ability to reduce nitrates and/or nitrites under anoxic conditions. Results showed that the OHO fraction is more complex than currently accepted and, with respect to denitrification, can be more accurately subdivided into five functional groups, four of which interactively contribute to denitrification occurring in the system and one group that are non-denitrifying. These groups were defined as true denitrifiers (bacteria capable of both nitrate and nitrite reduction), incomplete denitrifiers (bacteria that reduced nitrates to nitrites with no further reduction of the nitrites produced), incomplete-nitrite reducers (bacteria capable of both nitrate and nitrite reduction, however, exhibiting severe inhibition of nitrite reduction by nitrates), exclusive nitrite reducers (bacteria only capable of reducing nitrites) and non-denitrifiers (bacteria not capable of nitrate or nitrite reduction).

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Effects of pH and alkalinity on sulfur-denitrification in a biological granular filter

Water Science & Technology ◽

10.2166/wst.1996.0391 ◽

1996 ◽

Vol 34 (1-2) ◽

pp. 355-362 ◽

Cited By ~ 16

Author(s):

Hiroaki Furumai ◽

Hideki Tagui ◽

Kenji Fujita

Keyword(s):

Enrichment Culture ◽

Nitrite Reduction ◽

The Other ◽

Nitrite Accumulation ◽

Ph Dependency ◽

Effects Of Ph ◽

Rapid Removal ◽

Nitrate And Nitrite ◽

The Relationship ◽

Biological Filters

Two laboratory-scale biological filters were operated to investigate the effects of alkalinity and pH on removal of nitrate and nitrite in sulfur denitrification filter processes. The concentration of sodium bicarbonate in the feed media was changed from 120 to 240 mg/l during about 3 months in a filter (Run A). The other filter was initially fed with 300 mg/l and then with 240 mg/l (Run B). The performance of the filter was monitored by measuring pH, nitrate, nitrite, sulfate, alkalinity, and thiosulfate. Nitrate concentration in effluent rapidly decreased to lower levels within several days for both filters after inoculation of enrichment culture of sulfur denitrifiers. However there was a large difference in removal of nitrite. When rapid removal of nitrate took place, nitrite accumulation was observed and remained while the bicarbonate concentration was 120 and 150 mg/l. On the other hand the nitrite accumulation disappeared when more bicarbonate (240 and 300 mg/l) was supplied. The experimental results indicated that the nitrite accumulation was closely related to pH condition and alkalinity level in the filter. The stable data of effluent water quality for 5 cases were collected and the relationship discussed between nitrite concentration and pH in effluents. The relationship indicated a strong pH dependency on nitrite accumulation below pH of 7.4. The pH condition around 7 is not so inhibitory to biological activity. Therefore, the pH within the biofilm would be low enough to suppress the nitrite reduction by sulfur denitrifiers, while the pH in effluent was not in the inhibitory range. It was recommended to keep the pH higher than 7.4 to prevent nitrite accumulation in the sulfur denitrification filter.

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