Full Scale SBR Municipal Wastewater Treatment Facility Utilization of Simultaneous Nitrification/Denitrification Coupled with Traditional Nitrogen Removal to Meet Water Criterion

Simultaneous nitrification denitrification (SND) is a well-established phenomenon in biological nutrient removal activated sludge systems. Study at a municipal wastewater treatment facility sought to determine nitrogen removal effectiveness within a full-scale sequential batch reactor (SBR) system utilizing SND in conjunction with traditional nitrogen removal. In addition to characterizing extent of SND, the research examined the ability of SND to meet state-based effluent water quality standards. At the selected facility, the average SND efficiency during a two-month sampling period was 52.8%, paralleling results from similar SBR municipal wastewater systems. The observed SBR system had removal efficiencies > 99% for the influent to effluent -N concentrations. The SND process also resulted in average NO3-NO2-N concentration that was 82% lower than the theoretical concentration under comparable circumstances. Overall, nitrogen removal for this SBR system was >99% which typified results in other SND systems, but at a higher Total Nitrogen removal rate.

Simultaneous nitrification and autotrophic denitrification in fluidized bed reactors using pyrite and elemental sulfur as electron donors

In this study, simultaneous nitrification and autotrophic denitrification (SNAD) with either elemental sulfur or pyrite were investigated in fluidized bed reactors in mesophilic conditions. The reactor performance was evaluated at different ammonium (12-40 mg/L of NH4+-N), nitrate (35-45 mg/L of NO3--N), and dissolved oxygen (DO) (0.1-1.5 mg/L) concentrations, with a hydraulic retention time of 12 h. The pyrite reactor supported the SNAD process with a maximum nitrogen removal efficiency of 139.5 mg/(L·d) when the DO concentration was in the range of 0.8-1.5 mg/L. This range, however, limited the denitrification efficiency of the reactor, which decreased from 90.0% ± 5.3% in phases II-V to 67.9% ± 7.2% in phases VI and VII. Sulfate precipitated as iron sulfate (FeSO4/Fe2(SO4)3) and sodium sulfate (Na2SO4) minerals during the experiment. The sulfur reactor did not respond well to nitrification with a low and unstable ammonium removal efficiency, while denitrification occurred with a nitrate removal efficiency of 97.8%. In the pyrite system, the nitrifying bacterium Nitrosomonas sp. was present, and its relative abundance increased from 0.1% to 1.1%, while the autotrophic denitrifying genera Terrimonas, Ferruginibacter, and Denitratimonas dominated the community. Thiobacillus, Sulfurovum, and Trichlorobacter were the most abundant genera in the sulfur reactor during the entire experiment.

Simultaneous desulfurization and denitrification of sintering flue gas via composite absorbent

Experiments on simultaneous absorption of SO_2 and NO_X from sintering flue gas via a composite absorbent NaClO_2/NaClO were carried out. The effects of various operating parameters such as NaClO_2 concentration(ms), NaClO concentration(mp), molar ratio of NaClO_2/NaClO(M), solution temperature(TR), initial solution pH, gas flow(Vg) and inlet concentration of SO_2(CS) and NO(CN) on the removal efficiencies of SO_2 and NO were discussed. The optimal experimental conditions were determined to be initial solution pH = 6, TR=55 °C and M = 1.3 under which the average efficiencies of desulfurization and denitrification could reach99.7% and 90.8%, respectively. Moreover, according to the analysis of reaction products, it was found that adding NaClO to NaClO_2 aqueous solution is favorable for the generation of ClO_2 and Cl_2 which have significant effect on desulfurization and denitrification. Finally, engineering experiments were performed and obtained good results demonstrating that this method is practicable and promising.

Simultaneous nitrification and denitrification in step feeding biological nitrogen removal process

The simultaneous nitrification and denitrification in step-feeding biological nitrogen removal process were investigated under different influent substrate concentrations and aeration flow rates. Biological occurrence of simultaneous nitrification and denitrification was verified in the aspect of nitrogen mass balance and alkalinity. The experimental results also showed that there was a distinct linear relationship between simultaneous nitrification and denitrification and DO concentration under the conditions of low and high aeration flow rate. In each experimental run the floc sizes of activated sludge were also measured and the results showed that simultaneous nitrification and denitrification could occur with very small size of floc.

Effects of COD/N ratio and DO concentration on simultaneous nitrification and denitrification in an airlift internal circulation membrane bioreactor

The effects of chemical oxygen demand and nitrogen(COD/N)ratio and dissolved oxygen concentration(DO)on simultaneous nitrification and denitrification(SND)were investigated using an airlift internal circulation membrane bioreactor(AIC-MBR)with synthetic wastewater.The results showed that the COD efficiencies were consistently greater than 90% regardless of changes in the COD/N ratio.At the COD/N ratio of 4.77 and 10.04,the system nitrogen removal efficiency became higher than 70%.However,the nitrogen remova...

Nitrogen Removal by Simultaneous Nitrification and Denitrification via Nitrite in a Sequence Hybrid Biological Reactor

Sequence hybrid biological reactor （SHBR） was proposed, and some key control parameters were investigated for nitrogen removal from wastewater by simultaneous nitrification and denitrification （SND） via nitrite. SND via nitrite was achieved in SHBR by controlling demand oxygen （DO） concentration. There was a programmed decrease of the DO from 2.50 mg·L^-1 to 0.30 mg·L^-1, and the average nitrite accumulation rate （NAR） was increased from 16.5% to 95.5% in 3 weeks. Subsequently, further increase in DO concentration to 1.50 mg·L^-1 did not destroy the partial nitrification to nitrite. The results showed that limited air flow rate to cause oxygen deficiency in the reactor would eventually induce only nitrification to nitrite and not further to nitrate. Nitrogen removal efficiency was increased with the increase in NAR, that is, NAR was increased from 60% to 90%, and total nitrogen removal efficiency was increased from 68% to 85%. The SHBR could tolerate high organic loading rate （OLR）, COD and ammonia-nitrogen removal efficiency were greater than 92% and 93.5%, respectively,, and it even operated under low DO concentration （0.5 mg·L^-1） and maintained high OLR （4.0 kg COD·m^-3·d^-1）. The presence of biofilm positively affected the activated sludge settling capability, and sludge volume index （SVI） of activated sludge in SHBR never hit more than 90 ml·L^-1 throughout the experiments.

Experimental study on the simultaneous desulfurization and denitrification by duct injection

The highly active absorbent with oxidization based on fly ash, lime and additive was prepared. Experiments of simultaneous desulfurization and denitrification were carried out using fixture bed and duct injection. The influencial factors for the absorptive capacity of the absorbent were studied. The absorptive capacities of 120.7 mg for SO 2 and 43.7 mg for NOx were achieved at a Ca/(S+N) molar ratio 1.2, respectively, corresponding removal efficiencies of 87% and 76%, while spent absorbent appeared in the form of dry powder. The optimal temperature and humidity of flue gas treated with this process were shown to be approximately 50℃, and 5% respectively. The mechanism of removal for SO 2 and NOx was investigated. In comparison with traditional dry FGD, this process appears to have lower cost, less complicated configuration and simpler disposal of used absorbent. The valuable references can be provided for industrial application by this process. The foreground of application will be vast in China and in the world.

Cultivation of aerobic granules for simultaneous nitrification and denitrification by seeding different inoculated sludge

Cultivation of aerobic granules for simultaneous nitrification and denitrification in two sequencing batch airlift bioreactors was studied. Conventional activated floc and anaerobic granules served as main two inoculated sludge in the systems. Morphological variations of sludge in the reactors were observed. It was found that the cultivation of aerobic granules was closely associated with the kind of inoculated sludge. Round and regular aerobic granules were prevailed in both reactors, and the physical characteristics of the aerobic granules in terms of settling ability, specific gravity, and ratio of water containing were distinct when the inoculate sludge was different. Aerobic granules formed by seeding activated floc are more excellent in simultaneous nitrification and denitrification than that by aerobic granules formed from anaerobic granules. It was concluded that inoculated sludge plays a crucial role in the cultivation of aerobic granules for simultaneous nitrification and denitrification.

Eubacteria and Archaea community of simultaneous methanogenesis and denitrification granular sludge

Based on the successful performance of a lab-scale upflow anaerobic sludge blanket （UASB） reactor with the capacity of simultaneous methanogenesis and denitrification （SMD）, the specific phylogenetic groups and community structure of microbes in the SMD granule in the UASB reactor were investigated by the construction of the Eubacteria and Archaea 16S rDNA clone libraries, fragment length polymorphism, and sequence blast. Real time quantitative-polymerase chain reaction （RTQ-PCR） technique was used to quantify the contents of Eubacteria and Archaea in the SMD granule. The contents of some special predominant methanogens were also investigated. The results indicated that the Methanosaeta and Methanobacteria were the predominant methanogens in all Archaea in the SMD granule, with contents of 71.59% and 22.73% in all 88 random Archaea clones, respectively. The diversity of Eubacteria was much more complex than that of Archaea. The low GC positive gram bacteria and ε-Protebacteria were the main predominant Eubacteria species in SMD granule, their contents were 49.62% and 12.03% in all 133 random Eubacteria clones respectively. The results of RTQ-PCR indicated that the content of Archaea was less than Eubacteria, the Archaea content in total microorganisms in SMD granule was about 27.6%.

Simultaneous heterotrophic nitrification and aerobic denitrification at high initial phenol concentration by isolated bacterium Diaphorobacter sp. PD-7

A strain capable of phenol degradation, hetemtrophic nitrification and aerobic denitrification was isolated from activated sludge of coking-plant wastewater ponds under aerobic condition. Based on its morphology, physiology, biochemical analysis and phylogenetic characteristics, the isolate was identified as Diaphorobacter sp. PD-7. Biodegradation tests of phenol showed that the maximum phenol degradation occurred at the late phase of exponential growth stages, with 1400 mg·L^-1 phenol completely degraded within 85 h. Diaphorobacter sp. PD-7 accumulated a vast quantity of phenol hydroxylase in this physiological phase, ensuring that the cells quickly utilize phenol as a sole carbon and energy source. The kinetic behavior ofDiaphorobacter sp. PD-7 in batch cultures was investigated over a wide range of initial phenol concentrations （0-1400mg·L^-1） by using the Haldane model, which adequately describes the dynamic behavior of phenol biodegradation by strain Diaphombacter sp. PD-7. At initial phenol concentration of 1400mg· L^-l, batch experiments （0.25 L flask） of nitrogen removal under aerobic condition gave almost entirely removal of 120.69mg· L^- 1 ammonium nitrogen within 75 h, while nitrate nitrogen removal reached 91% within 65 h. Moreover, hydroxylamine oxidase, periplasmic nitrate reductase and nitrite reductase were successfully expressed in the isolate.

Simultaneous nitrification and denitrification conducted by Halomonas venusta MA-ZP17-13 under low temperature conditions

Nitrification is a key step in the global nitrogen cycle.Compared with autotrophic nitrification,heterotrophic nitrification remains poorly understood.In this study,Halomonas venusta MA-ZP17-13,isolated from seawater in shrimp aquaculture (Penaeus vannamei),could simultaneously undertake nitrification and denitrification.With the initial ammonium concentration at 100 mg/L,the maximum ammonium-nitrogen removal rate reached98.7%under the optimal conditions including C/N concentration ratio at 5.95,p H at 8.93,and Na Cl at 2.33%.The corresponding average removal rate was 1.37 mg/(L·h)(according to nitrogen) in 3 d at 11.2℃.By whole genome sequencing and analysis,nitrification-and denitrification-related genes were identified,including ammonia monooxygenase,nitrate reductase,nitrite reductase,nitric oxide dioxygenase and nitric oxide synthase;while no gene encoding hydroxylamine oxidase was identified,it implied the existence of a novel nitrification pathway from hydroxylamine to nitrate.These results indicate heterotrophic bacterium H.venusta MA-ZP17-13 can undertake simultaneous nitrification and denitrification at low temperature and has potential for NH_(4)^(+)-N/NH_(3)-N removal in marine aquaculture systems.

Performance of simultaneous nitrification and denitrification in lateral flow biological aerated filter

A new wastewater treatment facility—lateral flow biological aerated filter (LBAF) was developed aiming at solving energy consumption and operational problems in wastewater treatment facilities in small towns. It has the function of nitrification and removing organic substrate. In this study, we focused on the denitrification performance of LBAF and its possible mechanism under thorough aeration. We identified the existence of simultaneous nitrification and denitrification (SND) by analyzing nitrogenous compounds along the flow path of LBAF and supportive microbial microscopy, and studied the effects of air/water ratio and hydraulic loading on the performance of nitrogen removal and on SND in LBAF to find out the optimal operation condition. It is found that for saving operation cost, aeration can be reduced to some degree that allows desirable removal efficiency of pollutants, and the optimal air/water ratio is 10:1. Hydraulic loading less than 0.43 m h?1 hardly affects the nitrification and denitrification performance; whereas higher hydraulic loading is unfavorable to both nitrification and denitrification, far more unfavorable to denitrification than to nitrification.

Control strategy of simultaneous nitrification and denitrification in SBR system

The influence of main process parameters on simultaneous nitrification and denitrification （SND） in a sequencing batch reactor （SBR） were investigated while treating actual municipal sewage. The influent average concentration of CODcr and total nitrogen was 350mg-L-l and 35mg.L-l. The experiment indicated the following four operation control strategies： （1） When operation cycle was 6 hours, oxidation of organic pollutants and simultaneous nitrification and denitrification could well completed in the SBR reactor; （2） TN removal rate could be increased significantly, 40% higher than traditional SBR processes when idle period was set between influent and aeration; （3） The time of idle period could affect simultaneous nitrification and denitrification and the best time is 30 minutes; （4） Increase of sludge organic load may improve TN removal efficiency, but NH3-N removal efficiency declines.

Nitrification and Denitrification Activities and N_2O Emission of Orchard Soils Cultivated for Different Periods of Time

[Objective] The aim was to investigate the differences in nitrification and denitrification activities and the N20 emission of orchard soils cultivated for different periods of time. [Method] Incubation experiment was conducted to determine the ni- trification and denitrification activities and N20 emission of three types of orchard soil samples that had been cultivated for 5, 12 and 20 years, respectively, by using the virgin soil sample as control. [Result] After 26 d of incubation, the nitrification rates of nitrogen fertilizer in the virgin soil sample and the orchard soil samples cultivated for 5, 12 and 20 years were 6.85%, 10.26%, 13.29% and 12.90%, respectively, which were positively correlated with content of soil organic matter, ammonium nitro- gen and total nitrogen （P〈0.05）, and negatively correlated with soil carbon-nitrogen ratio and pH value （P〈0.05）. The denitrification activities of these soil samples in- creased with the increase of cultivation years. The amount of nitrogen loss by deni- trification accounted for 0.01%-3.11% of the amount of fertilizer nitrogen, and had a positive correlation with the content of soil organic matter （P〈0.05）. The N20 emis- sions of orchard soil samples were higher than that of the virgin soil samples （P〈 0.05）. [Conclusion] In South China, the nitrification activity of orchard soil is relatively low, but it has a tendency to increase as the cultivation years increases; the denitri- fication activity is relatively high, and increases significantly with the increase of culti- vation years.

Nitrogen Release Kinetics and Nitrification-Denitrification on Surface Sediments under Aerating Disturbance Condition

[Objective] This study aimed to investigate the nitrogen release kinetics and nitrification-denitrification on surface sediments under aerating disturbance condition, with the purpose to solve the sediment nitrogen release and secondary pollution problems. [Method] The effect of in situ sediments aeration on the release of nitrogen pollutants was investigated, and the nitrogen release kinetics parameters were analyzed. The process of nitrification and denitrification under sediments aeration condition was investigated in laboratory. [Result] The nitrogen released from sediments was enhanced by aeration disturbance. The concentration of NH4＋-N and TN reached the maximum value in 30 min, and release rates were proportional to the disturbance strength. In this study, with the distance of aerator to the sediments surface of 0, 1, 2 and 3 cm, the suspended sediments concentrations were 3.52, 3.41, 3.26 and 3.01 g/L, respectively. Maximum release concentration of NH4＋-N and TN were 14.3, 13.8, 13.2, 12.2 mg/L and 33.21, 30.98, 29.83, 27.30 mg/L, respec- tively. In addition, both NH4＋-N and TN release kinetics could be described by Double Constant Equation as InC=A＋Blnt. Nitrification reaction occurred and was promoted by continued aerating to sediments.The concentration of NH4＋-N dropped down from 12.4 mg/L to 0.2 mg/L in 8 d, with the concentration of NO3--N increased to the maximum value of 10.8 mg/L. In addition, concentration of NO3--N and TN decreased from 10.8 mg/L and 37.4 mg/L to 0.36 mg/L and 23.2 mg/L after the stop of aeration for 12 d, indicating the occurrence of denitdfication reaction. Therefore, sediment aeration could accelerate nitrogen release and nitrification reaction, and with intermittent aeration, nitrogen could be removed from sediments in-situ by nitrification and denitrification. [Conclusion] The results provided technical reference for the in situ sediment remediation for the black-odor rivers in cities.

Effects of chlorothalonil and carbendazim on nitrification and denitrification in soils

The effects of chlorothalonil and carbendazim on nitrification and denitrification in six soils in upland and rice paddy environments were investigated. Laboratory aerobic （60% water holding capacity） and anaerobic （flooded） conditions were studied at 25℃ and fungicide addition rates of 5.5 mg/kg A. I. （field rate, FR）, 20 times （20FR） and 40 times （40FR） field rate, respectively. The results indicated that chlorothalonil at the field rate had a slight inhibitory effect on one soil only, and that soil did not nitrify much in the first place. But chlorothalonil at higher rates inhibited nitrification significantly in all soils. For soils JXP and JXU with a pH of less than 5.0, chlorothalonil almost completely stopped their nitrification at 20FR and 40FR during the whole 14 d incubation period. For soils HNP and HNU with a pH of greater than 8.0, chlorothalonil also significantly inhibit nitrification at 20FR and 40FR （p 〈 0.05）. However, NH4＋ that was added to the soil was also almost completely nitrified by the end of the incubation period in these two soils. The effects of chlorothalonil at 20FR and 40FR on the nitrification of JSP and JSU soils, with a pH of 5.4 and 7.2, respectively, were intermediate between the other soil types. Chlorothalonil had no effect on denitrification at the field rate and had little effect at the higher rates of application in some soils. Carbendazim had essentially no effect on nitrification and denitrification in soils assessed.

Temperature effect on aerobic denitrification and nitrification

Nitrogen loss without organic removal in biofilter was observed and its possible reason was explained. A lower hydraulic loading could improve aerobic denitrification rate. Aerobic denitrification was seriously affected by low temperature(below 10℃). However, nitrification rate remained high when the temperature dropped from 15℃ to 5℃. It seemed the autotrophic biofilm in BAF could alleviate the adverse effect of low temperature.

Determination of respiration, gross nitrification and denitrification in soil profile using BaPS system

A facility of BaPS （Barometric Process Separation） was used to determine soil respiration, gross nitrification and denitrification in a winter wheat field with depths of 0-7, 7--14 and 14-21 cm. N2O production was determined by a gas chromatograph. Crop root mass and relevant soil parameters were measured. Results showed that soil respiration and gross nitrification decreased with the increase of soil depth, while denitrification did not change significantly. In comparison with no-plowing plot, soil respiration increased significantly in plowing plot, especially in the surface soil of 0-7 cm, while gross nitrification and denitrification rates were not affected by plowing. Cropping practice in previous season was found to affect soil gross nitrification in the following wheat-growing season. Higher gross nitrification rate occurred in the filed plot with preceding crop of rice compared with that of maize for all the three depths of 0-7, 7-14 and 14-21 cm. A further investigation indicated that the nitrification for all the cases accounted for about 76% of the total nitrogen transformation processes of nitrification and denitrification and the N2O production correlated with nitrification significantly, suggesting that nitrification is a key process of soil N2O production in the wheat field. In addition, the variations of soil respiration and gross nitrification were exponentially dependent on root mass （p〈0.00l）.

Removal of organic matter and nitrogen from distillery wastewater by a combination of methane fermentation and denitrification/nitrification processes

The distillery wastewater of Guangdong Jiujiang Distillery, which is characteristic of containing high organic matters and rich total nitrogen, was treated by a combination of methane fermentation and denitrification/nitrification processes. 80% of COD in the raw wastewater was removed by methane fermentation at the COD volumetric loading rate of 20 kg COD/（m^3·d） using the expanded granule sludge bed （EGSB） process. However, almost all the organic nitrogen in the raw wastewater was converted into ammonia by ammonification there. Ammonia and volatile fatty acids （VFA） remaining in the anaerobically treated wastewater were simultaneously removed utilizing VFA as an electron donor by denitrification occurring in the other EGSB reactor and nitrification using PEG-immobilized nitrifying bacteria with recirculation process. An aerobic biological contact oxidization reactor was designed between denitrification/nitrification reactor for further COD removal. With the above treatment system, 18000-28000 mg/L of COD in raw wastewater was reduced to less than 100 mg/L. Also, ammonia in the effluent of the system was not detected and the system had a high removal rate for 900-1200 mg/L of TN in the raw wastewater, only leaving 400 mg/L of nitrate nitrogen.