Effect of long-term idle periods on the performance of sequencing batch reactors

2000 ◽  
Vol 41 (1) ◽  
pp. 105-113 ◽  
Author(s):  
E. Morgenroth ◽  
A. Obermayer ◽  
E. Arnold ◽  
A. Brühl ◽  
M. Wagner ◽  
...  
Keyword(s):  
Ammonia Oxidation ◽  
Heterotrophic Bacteria ◽  
Batch Reactor ◽  
Effective Control ◽  
Nitrite Accumulation ◽  
Gene Probe ◽  
Minor Effect ◽  
Batch Reactors ◽  
A Minor

Sludge storage can be used as an effective control handle to adjust plant capacity to large influent variations. The sequencing batch reactor (SBR) technology is well suited for temporary sludge storage because reactors can easily be switched off individually and operated in an idle mode. In this study experimental results on the effect of long term (weeks) idle periods on nitrogen removal are presented. The SBRs were operated with idle times ranging from 6 to 20 days. Batch experiments were performed where sludge was stored without the addition of any substrate for 7 weeks. In the SBRs, repeated long-term idle phases had only a minor effect on ammonia oxidation. The nitrite oxidation process was more sensitive to long idle phases resulting in temporary nitrite accumulation in the SBRs. Quantitative gene probe analyses demonstrated that the decay of ammonia oxidizers was slower than the decay of nitrite oxidizers which in turn decayed slower than heterotrophic bacteria.

Dynamic mathematical modelling of sequencing batch reactors with aerated and mixed filling period

1997 ◽  
Vol 35 (1) ◽  
pp. 105-112 ◽  
Author(s):  
L. Novák ◽  
M. C. Goronszy ◽  
J. Wanner
Keyword(s):  
Activated Sludge ◽  
Batch Reactor ◽  
Major Elements ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Nitrogen And Phosphorus ◽  
Sludge Flocs ◽  
Solids Concentration ◽  
A Minor ◽  
Selection Of

Sequencing batch reactors (SBRs) can be successfully operated for both carbon and nutrient removal, including nitrogen and phosphorus. The major elements of design that accomplish population dynamics control to prevent filamentous sludge bulking, cycle time, oxygen supply, biological nitrification, denitrification, phosphorus removal and solids-liquid separation need to be set in such a way that sufficiently optimal conditions are provided to permit the reactions and processes to take place. SBR processing using cyclic activated sludge technology employs biological selectors in the inlet part of the SBR system and a minor sludge recycle stream to ensure influent wastewater is mixed with activated sludge flocs to create favourable conditions for kinetic and metabolic selection of microorganisms producing floccules. Reaction volume, in addition to the designated bottom water level volume, is variable through time fed-batch reactor mode of operation. A mathematical model that describes volume changes and simultaneously the biodegradation kinetics has been developed. The model describes theoretical behaviour of selected parameters of volume, suspended solids concentration, OUR, ammonia and nitrate nitrogen in the selector compartment and the main aerated basin in ideally mixed and filled reactors of the cyclic system during the phase of mixed-fill (selector) and aerated and non-aerated fill (main aeration reactor basin).

Effect of sludge discharge positions on steady-state aerobic granules in sequencing batch reactor (SBR)

2012 ◽  
Vol 66 (8) ◽  
pp. 1722-1727 ◽  
Author(s):  
Lin Liu ◽  
Da-Wen Gao ◽  
Hong Liang
Keyword(s):  
Steady State ◽  
Batch Reactor ◽  
Oxygen Demand ◽  
Aerobic Granule ◽  
Stable Operation ◽  
Batch Reactors ◽  
Aerobic Granules ◽  
Sequencing Batch Reactors ◽  
Discharge Location

We have investigated the effect of sludge discharge location on the steady-state aerobic granules in sequencing batch reactors (SBRs). Two SBRs were operated concurrently with the same sludge retention time using sludge discharge ports at: (a) the reactor bottom in R1; and (b) the reactor middle-lower level in R2. Results indicate that both reactors could maintain sludge granulation and stable operation, but the two different sludge discharge methods resulted in significantly different aerobic granule characteristics. Over 30 days, the chemical oxygen demand (COD) removal of the two reactors was maintained at similar levels (above 96%), and typical bioflocs were not observed. The average aerobic granule size in R2 was twice that in R1, as settling velocity increased in proportion to size increment. Meanwhile, the production yields of polysaccharide and protein content in R2 were always higher than those in R1. However, due to mass transfer limitations and the presence of anaerobes in the aerobic granule cores, larger granules had a tendency to disintegrate in R2. Thus, we conclude that a sludge discharge port situated at the reactor bottom is beneficial for aerobic granule stability, and enhances the potential for long-term aerobic granule SBR operation.

scholarly journals Impact of Protozoan Grazing on Nitrification and the Ammonia-And-Nitrite-Oxidizing Bacterial Communities in Activated Sludge

2021 ◽  
Author(s):  
Amy Jean Pogue
Keyword(s):  
Activated Sludge ◽  
Ammonia Oxidation ◽  
Heterotrophic Bacteria ◽  
Grazing Pressure ◽  
Batch Reactors ◽  
Protozoan Grazing ◽  
Nitrite Oxidizing Bacteria ◽  
Nitrogen Concentrations ◽  
Nitrite Nitrate

The effect of protozoan grazing on nitrification rates under different conditions was examined. The spatial distribution of ammonia -and nitrite- oxidizing bacteria (AOB and NOB) in activated sludge was also examined using FISH/CSLM. Batch reactors were monitored for ammonia, nitrite, nitrate, and total nitrogen concentrations and bacterial numbers in the presence and absence of cycloheximide, a protozoan inhibitor. In the absence of protozoan grazing, rates of nitrification were lower than in batches with protozoa. Spatially, both AOB and NOB were found clustered within the floc and neither inhibiting the protozoa or inhibiting ammonia oxidation appeared to lower the amount of AOB and NOB present or their position. These results suggest that a reduction in protozoan grazing pressure allowed the heterotrophic bacteria to proliferate which caused a corresponding decrease in the rate of nitrification. These results suggest that AOB and NOB are less active in the absence of protozoa and indicates the role of protozoa in the cycling of nitrogen.

Nitritation of real sewage: start-up and maintenance by the side-stream heat-shock treatment

2019 ◽  
Vol 79 (4) ◽  
pp. 753-758 ◽  
Author(s):  
Jianfei Chen ◽  
Shujun Zhang ◽  
Xiaoyu Han ◽  
Liang Zhang ◽  
Yongzhen Peng
Keyword(s):  
Heat Shock ◽  
Accumulation Rate ◽  
Batch Reactor ◽  
Shock Treatment ◽  
Nitrite Accumulation ◽  
Heat Shock Treatment ◽  
Term Operation ◽  
Side Stream ◽  
Start Up

Abstract In this study, the side-stream heat-shock treatment was used to start up and maintain the nitritation of real sewage. Complete nitrification was obtained when the real sewage was treated in a sequencing batch reactor (SBR). Then, about 50% of the mixed sludge was collected from the SBR and treated with the heat-shock treatment at 60 °C for 40 min in another reactor every 2 weeks. After providing the heat-shock treatment for four times, the effluent nitrate in the SBR gradually decreased from 22.5 to 3.2 mg/L, while the nitrite accumulation rate increased from 4.4% to 81.8%, indicating a successful start-up of nitritation. Further, the sewage nitritation was stable with the regular side-steam heat-shock treatment for 91 days, and the ammonium removal efficiency of 80.6% and nitrite accumulation rate of 91.2% were achieved. This study suggests that the side-stream heat-shock treatment could be used to start up sewage nitritation and maintain stability for a long-term operation.

Partial Nitrification to Nitrite with Real-Time Aeration Duration Control in an SBR Treating Domestic Wastewater

2011 ◽  
Vol 356-360 ◽  
pp. 1046-1049 ◽  
Author(s):  
Yu Chen ◽  
Jun Li ◽  
C .W Wang ◽  
X.F Zhao ◽  
B.H Zhao
Keyword(s):  
Real Time ◽  
Batch Reactor ◽  
Domestic Wastewater ◽  
Partial Nitrification ◽  
Nitrite Accumulation ◽  
Ammonia Oxidizing Bacteria ◽  
Term Operation ◽  
Nitrite Oxidizing Bacteria ◽  
Low Strength

Sustainable partial nitrification to nitrite has been proven difficult in treating low strength nitrogenous wastewater. Real-time aeration duration control was used to achieve efficient partial nitrification to nitrite in a sequencing batch reactor (SBR) to treat low strength domestic wastewater. Above 95% nitrite accumulation ratio was maintained for long-term operation at normal condition. Partial nitrification established by controlling aeration duration showed good performance and robustness even though some time encountering long-term extended aeration. Process control enhanced the successful accumulation of ammonia oxidizing bacteria (AOB) and washout of nitrite oxidizing bacteria (NOB).

Rapid start-up and efficient long-term nitritation of low strength ammonium wastewater with a sequencing batch reactor containing immobilized cells

2014 ◽  
Vol 70 (3) ◽  
pp. 517-523 ◽  
Author(s):  
Hammad Khan ◽  
Wookeun Bae
Keyword(s):  
Sequencing Batch Reactor ◽  
Immobilized Cells ◽  
Batch Reactor ◽  
Linear Increase ◽  
Nitrite Accumulation ◽  
Ammonium Oxidation ◽  
Do Concentration ◽  
Low Strength ◽  
In The Beginning

Major concerns about nitritation of low-strength ammonium wastewaters include low ammonium loading rates (ALRs) (usually below 0.2 kg/m3-d) and uncertainty with the long-term stability of the process. The purpose of this study was to test a sequencing batch reactor filled with cell-immobilized polyethylene glycol (PEG) pellets (∼2 mm in size) to see if it could achieve efficient and stable nitritation under various environmental conditions. The sequencing batch reactor (SBR) was fed with synthetic ammonium wastewater of 30 ± 2 mg-N/L and pH 8 ± 0.05, maintaining the dissolved oxygen (DO) concentration at 1.7 ± 0.2 mg/L and the temperature at 30 ± 1 °C. The reaction was easily converted to partial nitrification mode within a month by feeding a relatively high ammonium substrate (∼100 mg-N/L) in the beginning. We observed stable nitritation over 300 days with high ALRs (as high as ∼1.1 kg-N/m3-d), nitrite accumulation rates (mostly over 97%), and ammonium removal rates (mostly over 95%). DO was the major limiting substrate when the DO concentration was below ∼4 mg/L and the NH4+-N concentration was above ∼5 mg/L, giving an almost linear increase in the ammonium oxidation rate with the bulk DO increase. Low temperatures mainly affected the reaction rate, which could be compensated for by increasing the pellet volume (i.e. biomass). Our results demonstrated that an SBR filled with small cell-immobilized PEG pellets could achieve very efficient and stable nitritation of a low-strength ammonium wastewater.

Stabilization of source-separated urine by biological nitrification process: treatment performance and nitrite accumulation

2012 ◽  
Vol 66 (7) ◽  
pp. 1491-1497 ◽  
Author(s):  
F. Y. Sun ◽  
W. Y. Dong ◽  
M. F. Shao ◽  
J. Li ◽  
L. Y. Peng
Keyword(s):  
Ammonia Oxidation ◽  
Great Influence ◽  
High Strength ◽  
Ammonia Concentration ◽  
Nitrite Accumulation ◽  
Batch Reactors ◽  
Ammonia Content ◽  
Free Nitrous Acid ◽  
Nitrification Process ◽  
Solids Retention

A laboratory study on nitrification of high-strength source-separated urine was conducted by means of sequencing batch reactors (SBR) and membrane bioreactors (MBR). The highest influent ammonia concentration for SBR and MBR reached more than 2,400 and 1,000 mg N/L, while the maximum pH was about 9 and 8.9, respectively. The ammonia oxidizing efficiency in both SBRs and MBRs was around 50%, which was restrained mainly by the deficiency of alkalinity in bulks. Meanwhile, the nitrite accumulation did also dominate in these two systems, and the major factor to inhibit the nitrite oxidization was thought to be the high free ammonia and free nitrous acid content in bulks. Hence, an ammonia nitrite solution was achieved with concentration ratio of 1:1; after that ammonia oxidation was restrained owing to the deficiency of alkalinity in urine. The temperature and influent ammonia content have no great influence on the nitrification process in both kinds of bioreactors. The nitrification can be progressed under a solids retention time (SRT) longer than 30 d; however, termination of ammonia oxidization was observed as the SRT fell below 20 d. The nitrifier biomass showed an excellent settleability, such that the suspended solids (SS) in effluent was of a low average, about 60 mg/L. This study on the stabilization of human urine will be useful to understand the process of urine separation from source.

scholarly journals Essential Role of Invasin for Colonization and Persistence of Yersinia enterocolitica in Its Natural Reservoir Host, the Pig

2013 ◽  
Vol 82 (3) ◽  
pp. 960-969 ◽  
Author(s):  
Julia Schaake ◽  
Anna Drees ◽  
Petra Grüning ◽  
Frank Uliczka ◽  
Fabio Pisano ◽  
...  
Keyword(s):  
Yersinia Enterocolitica ◽  
Reservoir Host ◽  
Infection Model ◽  
Minor Effect ◽  
Primary Role ◽  
Pathogenic Potential ◽  
Content Type ◽  
A Minor

ABSTRACTIn this study, an oral minipig infection model was established to investigate the pathogenicity ofYersinia enterocoliticabioserotype 4/O:3. O:3 strains are highly prevalent in pigs, which are usually symptomless carriers, and they represent the most common cause of human yersiniosis. To assess the pathogenic potential of the O:3 serotype, we compared the colonization properties ofY. enterocoliticaO:3 with O:8, a highly mouse-virulentY. enterocoliticaserotype, in minipigs and mice. We found that O:3 is a significantly better colonizer of swine than is O:8. Coinfection studies with O:3 mutant strains demonstrated that small variations within the O:3 genome leading to higher amounts of the primary adhesion factor invasin (InvA) improved colonization and/or survival of this serotype in swine but had only a minor effect on the colonization of mice. We further demonstrated that a deletion of theinvAgene abolished long-term colonization in the pigs. Our results indicate a primary role for invasin in naturally occurringY. enterocoliticaO:3 infections in pigs and reveal a higher adaptation of O:3 than O:8 strains to their natural pig reservoir host.

scholarly journals Rapid cultivation and stability of autotrophic nitrifying granular sludge

2020 ◽  
Vol 81 (2) ◽  
pp. 309-320 ◽  
Author(s):  
Linan Zhang ◽  
Bei Long ◽  
Yuanyuan Cheng ◽  
Junfeng Wu ◽  
Binchao Zhang ◽  
...  
Keyword(s):  
Heterotrophic Bacteria ◽  
Accumulation Rate ◽  
Removal Rate ◽  
Granular Sludge ◽  
Ammonia Nitrogen ◽  
Nitrifying Bacteria ◽  
Structure Stability ◽  
Nitrite Accumulation ◽  
Term Operation

Abstract Autotrophic nitrifying granular sludge (ANGS) was cultivated by gradually decreasing the influent organics and adding exogenous nitrifying bacteria. Under the strategy, ANGS was domesticated within 36 days. Stability of the seed heterotrophic granules decreased significantly during conversion of organic wastewater to inorganic ammonia wastewater. Obvious granular breakage was observed during these days. However, the granular debris still had good settlement performance. With microbes gradually acclimated to the new environment, the debris provided a large number of carriers for the attached growth of the exogenous nitrifying bacteria, and they replaced the heterotrophic bacteria and became the dominant species. The domesticated ANGS showed good nitrification performance during the 37th to the 183rd day (ammonia nitrogen load between 0.28 and 0.29 kg/m3 · d). The removal rate of ammonia nitrogen was usually more than 95%, and nitrite accumulation rate was always larger than 50%. However, nitrification ability was gradually lost with the increase of the ammonia nitrogen load (0.3–0.64 kg/m3 · d) from the 184th day, and it almost approached the influent ammonia nitrogen at the 269th day. Interestingly, good structure stability of the ANGS was maintained during long-term operation, and the ANGS became smoother and denser at the end of the experiment.

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