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1.
Static experiments were conducted to investigate the effects of environmental factors on nitrate (NO3?-N)-removal efficiency, such as NO3?-N loading, pH value, C/N ratio and temperature in activated sludge using Fe (II) as electron donor. The results demonstrated that the average denitrification rate increased from 1.25 to 2.23 mg NO3?-N/(L·h) with NO3?-N loading increased from 30 to 60 mg/L. When pH increased from 7 to 8, the concentration of NO3?-N and nitrite (NO2?-N) in effluent were all maintained at quite low levels. C/N ratio had little impact on denitrification process, i.e., inorganic carbon (C) source could still be enough for denitrification process with C/N ratio as low as 5. Temperature had a significant effect on the denitrification efficiency, and NO3?-N removal efficiency of 92.03%, 96.77%, 97.67% and 98.23% could be obtained with temperature of 25°C, 30°C, 35°C and 40°C, respectively. SEM, XRD and XRF analysis was used to investigate microscopic surface morphology and chemical composition of the denitrifying activated sludge, and mechanism of the nitrate-dependent anaerobic ferrous oxidation (NAFO) bacterias could be explored with this research.  相似文献   

2.
The treatment capacity of an integrated constructed wetland system (CWS) that was designed to reduce nitrogen (N) from secondary effluent was explored. The integrated CWS consisted of vertical-flow constructed wetland, floating bed and sand filter. The vertical-flow wetland was filled with gravel, steel slag and peat from the bottom to the top. Vetiver zizanioides was selected to grow in the vertical-flow constructed wetland and Coix lacrymajobi L. was grown in the floating bed. The results showed that the integrated CWS displayed superior removal efficiency for nitrate nitrogen (NO3-N), ammonia nitrogen (NH4+-N), nitrite nitrogen (NO2-N), and total nitrogen (TN). The average NO3-N, NO2-N, NH4+-N and TN removal efficiencies of the integrated CWS were 98.83%, 95.60%, 98.05% and 92.41%, respectively, during the whole experimental operation. The integrated CWS may have a good potential for removing N from secondary effluent.  相似文献   

3.
Huang B  Chi G  Chen X  Shi Y 《Bioresource technology》2011,102(21):10154-10157
The performance of acetic acid-supported pH-heterogenized heterotrophic denitrification (HD) facilitated with ferrous sulfide-based autotrophic denitrification (AD) was investigated in upflow activated carbon-packed column reactors for reliable removal of highly elevated nitrate (42 mg NO3-N l−1) in drinking water. The use of acetic acid as substrate provided sufficient internal carbon dioxide to completely eliminate the need of external pH adjustment for HD, but simultaneously created vertically heterogenized pH varying from 4.8 to 7.8 in the HD reactor. After 5-week acclimation, the HD reactor developed a moderate nitrate removal capacity with about one third of nitrate removal occurring in the acidic zone (pH 4.8–6.2). To increase the treatment reliability, acetic acid-supported HD was operated under 10% carbon limitation to remove >85% of nitrate, and ferrous sulfide-based AD was supplementally operated to remove residual nitrate and formed nitrite without excess of soluble organic carbon, nitrite or sulfate in the final effluent.  相似文献   

4.
Removal of three typical aromatic hydrocarbons, benzene, biphenyl and naphthalene by an anaerobic filter (AF) reactor under continuous mode and denitrifying conditions was studied. Results showed that the AF reactor could degrade these aromatic hydrocarbons effectively under above-mentioned conditions. When influent wastewater contained 900 mg COD/l and about 60 mg (total aromatic hydrocarbons)/l, 90% and 84% removal efficiency could be achieved for them respectively. When COD/NO3 -N ratio (C/N) was in the range 5–30, the removal of benzene was slightly influenced by C/N and it remained stable at about 90%. However, degradation of naphthalene, biphenyl and total COD was greatly influenced by C/N, and highest removal was achieved at C/N = 15, it was 90%, 85% and 82% for COD, naphthalene and biphenyl, respectively. Degradation of these three aromatic hydrocarbons followed the order: benzene > naphthalene > biphenyl.  相似文献   

5.
This study shows how the carbon and nitrogen (C/N) ratio controls the simultaneous occurrence of nitrification and denitrification in a sequencing batch reactor (SBR). Data demonstrated that a low C/N ratio resulted in a rapid carbon deficit, causing an unbalanced simultaneous nitrification–denitrification (SND) process in SBR. When the initial COD/NH4+-N ratio was adjusted to 11.1, the SND-based SBR achieved complete removal of NH4-N and COD without leaving any NO2-N in the effluent. The nitrogen removal efficiency decreases gradually with increasing ammonium-loading rate to the SND–SBR system. Altogether, data showed that appropriate controls of carbon and nitrogen input are required to achieve an efficient SND–SBR. An established SND technology can save operation time and energy, and might replace the traditional two-stage biological nitrification and denitrification process.  相似文献   

6.
Taking advantage of the good biocompatibility and high efficiency of nitrogen removal with microbes, nitrifying and denitrifying bacteria, are becoming increasingly more widely used for wastewater treatment and prevention of eutrophication. In this research, an aerobic nitrifying-denitrifying bacterium was successfully screened from activated sludge and identified as Pseudomonas sp. (CCTCC No M2010209) by the 16S rDNA sequence. The activity verification confirmed its nitrifying-denitrifying capability of removing ammonium, nitrate and nitrite nitrogen. The types of carbon sources and carbon-nitrogen ratio greatly influenced the removal efficiency of NH4 +-N and NO3 -N. When the initial concentrations of NH4 +-N and NO3 -N in synthetic wastewater were less than 70 and 50 mg/L, the nitrogen removal rates reached 94 and 90% in 9 h, respectively. Preliminary comparisons of nitrogen removal capacity between this isolate and other commercial preparations in the treatment of synthetic wastewater revealed its promising potential to be used in the actual wastewater treatment.  相似文献   

7.
A bioreactor for the removal of nitrate nitrogen (NO3-N) from industrial effluent is described which is comprised of a glass column (60 cm × 6 cm) packed with alginate beads containing denitrifying organisms Pseudomonas stutzeri and Comamonas testosteroni. The effluent containing high concentrations of nitrate (600–950 mg l–1) from the fertilizer industry and fusel oil (methanol as a major component) as organic carbon were used in the process. The reactor is operated in the continuous mode by injecting the pretreated nitrate-containing effluent at the top of the column. The Hydraulic retention time (HRT) was adjusted by changing the flow rates. When nitrate-containing wastewater was treated with immobilized cells, the nitrate removal rate reached a maximum 1.66 ± 0.07 Kg NO3-N m–3d–1 at an influent NO3-N concentration of 850 mg NO3M-N l–1within 12 h. The denitrification activity of the immobilized cells was compared with that of the free cells.  相似文献   

8.
Aerobic granular sludge was successfully cultivated with the effluent of internal circulation (IC) reactor in a pilot-scale sequencing batch reactor (SBR) using activated sludge as seeding sludge. N removal was investigated in the start-up of aerobic granulation process. Initially, the phenomenon of partial nitrification was observed and nitrite accumulation rates (NO2 ?-N/NO x ? -N) were between 84.6 and 99.1?%. It was potentially caused by ammonium oxidizing bacteria (AOB) in the seeding activated sludge, high external environmental temperature (~32?°C) and free ammonia (FA) concentration. After 50?days’ running, the aerobic granules-based bioreactor demonstrated perfect performance in simultaneous removal of organic matter and ammonia nitrogen, and average removal efficiencies were maintained above 93 and 96?%, respectively. The maximum nitrogen removal efficiency of 83.1?% was achieved after the formation of aerobic granules. The average diameter of mature aerobic granular sludge mostly ranged from 0.5 to 1.0?mm. Furthermore, one typical cyclic test indicated that pH and DO profiles could be used as effective parameters for biological reactions occurring in the aerobic/anoxic process. The obtained results could provide further information on the cultivation of aerobic granular sludge with practical wastewater, especially with regard to nitrogen-rich industrial wastewater.  相似文献   

9.

Excess inorganic nitrogen in water poses a severe threat to enviroment. Removal of inorganic nitrogen by heterotrophic nitrifying–aerobic denitrifying microorganism is supposed to be a promising and applicable technology only if the removal rate can be maintained sufficiently high in real wastewater under various conditions, such as high concentration of salt and wide range of different nitrogen concentrations. Here, a new heterotrophic nitrifying–aerobic denitrifying bacterium was isolated and named as Pseudomonas mendocina TJPU04, which removes NH4+-N, NO3-N and NO2-N with average rate of 4.69, 5.60, 4.99 mg/L/h, respectively. It also maintains high nitrogen removal efficiency over a wide range of nitrogen concentrations. When concentration of NH4+-N, NO3-N and NO2-N was up to 150, 150 and 50 mg/L, 98%, 93%, and 100% removal efficiency could be obtained, respectively, after 30-h incubation under sterile condition. When it was applied under non-sterile condition, the ammonia removal efficiency was slightly lower than that under sterile condition. However, the nitrate and nitrite removal efficiencies under non-sterile condition were significantly higher than those under sterile condition. Strain TJPU04 also showed efficient nitrogen removal performance in the presence of high concentration of salt and nitrogen. In addition, the removal efficiencies of NH4+-N, NO3-N and TN in real wastewater were 91%, 52%, and 75%, respectively. These results suggest that strain TJPU04 is a promising candidate for efficient removal of inorganic nitrogen in wastewater treatment.

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10.
The treatment performance of an upflow microaerobic sludge blanket reactor (UMSB) for synthetic domestic wastewater was investigated at two dissolved oxygen (DO) levels, 0.3–0.5 and 0.7–0.9 mg l−1, focusing on nitrification performance. The higher DO level induced complete nitrification of ammonia nitrogen (NH3–N), achieving chemical oxygen demand and NH3–N removals of 97 and 92%, respectively. There were consistently significantly higher nitrate nitrogen (NO3–N) and nitrite nitrogen (NO2–N) levels in the effluent, with ~66% of newly-produced oxidised nitrogen as NO2–N. Despite the high nitrification efficiency, only about 23% of the removed NH3–N amount from the influent was ultimately transformed into oxidised nitrogen due to the simultaneous nitrification-denitrification. Sludge blanket development and granulation occurred simultaneously in the UMSB.  相似文献   

11.
The aerial microalga Trentepohlia aurea has beeninvestigated in relation to removal characteristics of nitrate, nitrite,ammonium and phosphate ions. When the alga was cultured in medium with veryhighconcentrations of ammonium, nitrate and phosphate ions, it showed relativelyhigh growth and removal rates. It also grew quite well with high nitriteconcentration (< 141 mg NO2-N L–1).The removal rate was 0.28 mg NO2-N L–1day–1 in the 40-day culture, when it was cultured in modifiedBold's basal medium with added 51 mg NO2-NL–1. In addition, we examined simultaneous removal of nutrientions. The biomass was 1.5 times higher in medium which N- and P-sourcesufficient than in ordinary medium. Higher removal ratios of nitrite andnitratefrom medium were shown in a 30-day culture, reaching 37% and 32%, respectively.It is concluded that T. aurea has the potential for use inthe purification of wastewater.  相似文献   

12.
A sequencing batch reactor (SBR) seeded with methanogenic granular sludge was started up to enrich Anammox (Anaerobic Ammonium Oxidation) bacteria and to investigate the feasibility of granulation of Anammox biomass. Research results showed that hydraulic retention time (HRT) was an important factor to enrich Anammox bacteria. When the HRT was controlled at 30 days during the initial cultivation, the SBR reactor presented Anammox activity at t = 58 days. Simultaneously, the methanogenic granular sludge changed gradually from dust black to brown colour and its diameter became smaller. At t = 90 days, the Anammox activity was further improved. NH4+-N and NO2N were removed simultaneously with higher speed and the maximum removal rates reached 14.6 g NH4+-N /(m3 reactor·day) and 6.67 g NO2-N /(m3 reactor·day), respectively. Between t = 110 days and t = 161 days, the nitrogen load was increased to a HRT of 5 days (70 mg/l NH4+ and 70 mg/l NO2), the removal rates of ammonium and nitrite were 60.6% and 62.5% respectively. The sludge changed to red and formed Anammox granulation with high nitrogen removal activity.  相似文献   

13.
Bacterial biofilters used in marine recirculation aquaculture systems need improvements to enhance nitrogen removal efficiency. Relatively little is known about biofilter autochthonous population structure and function. The present study was aimed at isolating and characterizing an autochthonous denitrifying bacterium from a marine biofilter installed at a recirculation aquaculture system. Colonization of four different media in a marine fish farm was followed by isolation of various denitrifying strains and molecular classification of the most promising one, strain T2, as a novel member of the Pseudomonas fluorescens cluster. This strain exhibits high metabolic versatility regarding N and C source utilization and environmental conditions for growth. It removed nitrate through aerobic assimilatory metabolism at a specific rate of 116.2 mg NO3-N g dw−1 h−1. Dissimilatory NO3-N removal was observed under oxic conditions at a limited rate, where transient NO2-N formed represented 22% (0.17 mg L−1) of the maximum transient NO2-N observed under anoxic conditions. Dissimilatory NO3-N removal under anoxic conditions occurred at a specific rate of 53.5 mg NO3-N g dw−1 h−1. The isolated denitrifying strain was able to colonize different materials, such as granular activated carbon (GAC), Filtralite and Bioflow plastic rings, which allow the development of a prototype bioreactor for strain characterization under dynamic conditions and mimicking fish-farm operating conditions.  相似文献   

14.
《Process Biochemistry》2004,39(11):1615-1624
Internal recycle ratio is an important parameter in anaerobic/anoxic/oxic (A2/O) wastewater treatment plant (WWTP) operation. An increase in this ratio decreases nitrate and nitrite concentration in the effluent and hence improves the nitrogen removal efficiency, even though the economical cost increases simultaneously. Determining the most favourable recycle ratio taking into account both considerations is an important item in A2/O WWTP operational optimisation. In this work, the effect of recycle ratio on nitrogen removal when using different influent nitrogen loads was tested in a pilot A2/O WWTP. Experimental results obtained show how increasing the internal recycle ratio from 0 to 5 produced a 12% increase in nitrogen removal. This increase was achieved by improving N–NOx removal by 9% with an increase in N–NH4+ removal of 3%.  相似文献   

15.
Of 14 potential sulfur-oxidizing strains, Pseudomonas sp. B21 and Agrobacterium sp. B19 were considered as denitrifiers. Under aerobic conditions, with S0 as electron donor, maximum cell growth rates were 0.022 (B21) and 0.043 h–1 (B19). Both grew optimally at pH 7.5 and 28 °C. When NO3-N was increased from 10 to 200 mg l–1 the efficiency of nitrate removal of each strain gradually decreased, from 60 to 40%. Addition of suitable organic compounds (C/N < 4.2) increased the nitrate removal efficiencies of both strains, indicating their mixotrophic characters.  相似文献   

16.
Simultaneous nitrification and denitrification using a mixed methanotrophic culture was investigated. When both NO3 -N (108 mg l–1) and NH3-N (59 mg l–1) were added into batch reactors, nitrate removal was complete within 10 h at the rate of 47 mg NO3 -N g VSS–1 day–1 when dissolved oxygen (DO) concentration was maintained at 2 mg DO l–1. Ammonia removal started simultaneously with nitrate removal at a slower rate of 14 NH3-N g VSS–1 day–1. No significant accumulation of nitrite or nitrate during ammonia utilization suggested the occurrence of simultaneous nitrification and denitrification.  相似文献   

17.
Microorganism with simultaneous nitrification and denitrification ability plays a significant role in nitrogen removal process, especially in the eutrophic waters with excessive nitrogen loads. The nitrogen removal capacity of microorganism may suffer from low temperature or nitrite nitrogen source. In this study, a hypothermia aerobic nitrite-denitrifying bacterium, Pseudomonas tolaasii strain Y-11, was selected to determine the simultaneous nitrification and denitrification ability with mixed nitrogen source at 15 °C. The sole nitrogen removal efficiencies of strain Y-11 in simulated wastewater were obtained. After 24 h of incubation at 15 °C, the ammonium nitrogen fell below the detection limit from an initial value of 10.99 mg/L. Approximately 88.0 ± 0.33% of nitrate nitrogen was removed with the initial concentration of 11.78 mg/L and the nitrite nitrogen was not detected with the initial concentration of 10.75 mg/L after 48 h of incubation at 15 °C. Additionally, the simultaneous nitrification and denitrification nitrogen removal ability of P. tolaasii strain Y-11 was evaluated using low concentration of mixed NH4+-N and NO3?–N/NO2?–N (about 5 mg/L-N each) and high concentration of mixed NH4+–N and NO3?–N/NO2?–N (about 100 mg/L-N each). There was no nitrite nitrogen accumulation at the time of evaluation. The results demonstrated that P. tolaasii strain Y-11 had higher simultaneous nitrification and denitrification capacity with low concentration of mixed inorganic nitrogen sources and may be applied in low temperature wastewater treatment.  相似文献   

18.
The primary objective of this study was to evaluate the effects of the organic loading rate on the performance of an up-flow anaerobic sludge blanket (UASB) reactor treating olive mill effluent (OME), based on the following indicators: (i) chemical oxygen demand (COD) removal efficiency; and (ii) effluent variability (phenol, suspended solids, volatile fatty acids, and pH stability). The UASB reactor was operated under different operational conditions (OLRs between 0.45 and 32 kg COD/m3·day) for 477 days. The results demonstrated that the UASB reactor could tolerate high influent COD concentrations. Removal efficiencies for the studied pollution parameters were found to be as follows: COD, 47∼92%; total phenol, 34∼75%; color, 6∼46%; suspended solids, 34∼76%. The levels of VFAs in the influent varied between 310 and 1,750 mg/L. Our measurements of the VFA levels indicated that some of the effluent COD could be attributed to VFAs (principally acetate, butyrate, iso-butyrate, and propionate) in the effluent, which occurred at levels between 345 and 2,420 mg/L. As the OLRs were increased, more VFAs were measured in the effluent. A COD removal efficiency of 90% could be achieved as long as OLR was kept at a level of less than 10 kg COD/m3·day. However, a secondary treatment unit for polishing purposes is necessary to comply with discharge standards.  相似文献   

19.
Summary In the combined ion exchange/biological denitrification process for nitrate removal from ground water, in which nitrate is removed by ion exchange, the resins are regenerated in a closed circuit by a biological denitrification reactor. This denitrification reactor eliminates nitrate from the regenerant. Methanol is used as electron donor for biological denitrification. To obtain sufficient regeneration of the resins within a reasonable time, high NaCl or NaHCO3 concentrations (10–30 g/l) in the regenerant are necessary. High NaHCO3 concentrations affected the biological denitrification in three ways: a) a slight decrease in denitrification capacity (30%) was observed; b) the yield coefficient and CH3OH/NO3 -–N ratio decreased. When high NaHCO3 concentrations (above 10g NaHCO3/l) were used, the yield coefficient was 0.10–0.13 g VSS/g NO3 -–N and the CH3OH/NO3 -–N ratio was 2.00–2.03 g/g; c) high NaHCO3 concentrations influenced nitrite production. Nitrite is an intermediate product of biological denitrification and with rising NaHCO3 concentrations nitrite accumulation was suppressed. This was explained by the effect of high NaHCO3 concentrations on the pH in the microenvironment of the denitrifying organisms. High NaCl concentrations also resulted in a slight decrease in denitrification capacity, but the second and third effects were not observed in the presence of high NaCl concentrations.Although the pH in the regenerant will rise as a result of biological denitrification, the capacity of a denitrification reactor did not decrease significantly when a pH of 8.8–9.2 was reached.  相似文献   

20.
Denitrification of a high-strength synthetic wastewater (150 g NO- 3 l-1) was carried out using a wine distillery effluent as an example of an industrial carbon source (22.7 g chemical oxygen demand l-1). Two configurations were tested: one consisted of an acidogenesis reactor followed by a denitrifying reactor and the other was a single reactor directly fed with the raw effluents. In both cases, denitrification was achieved at a nitrate load of 9.54 g NO- 3 l-1 day-1 (2.19 g N as NO- 3 l-1 day-1) with good specific reduction rates: 32.6 mg and 35.2 mg N as NO x  g volatile suspended solids h-1, calculated on a single day, for the two-step and the one-step process respectively. Dissimilatory nitrate reduction to ammonium did not occur, even in the one-step process. Received: 26 October 1995/Received revision: 15 February 1996/Accepted: 20 February 1996  相似文献   

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