scholarly journals A Better MLE Nitrification Process Adopted from STOAT Simulation Experiments

2021 ◽  
Vol 43 (6) ◽  
pp. 443-452
Author(s):  
Taewook Kim ◽  
Sunjoo Cho ◽  
Sung-Hyun Kwon ◽  
Daechul Cho
Keyword(s):  
Nitrogen Removal ◽  
Water Conservation ◽  
Reduction Rate ◽  
Ammonia Concentration ◽  
Nitrification Rate ◽  
Process Variables ◽  
Simulation Experiments ◽  
Nitrification Process ◽  
Do Concentration ◽  
Removal Processes

Objectives : Nitrogen removal processes are very important in terms of water conservation. Among them, the MLE process has been difficult to optimize because it has many variations and required experiences in operation.Methods : In this work, we quantitatively analyzed the nitrification of the MLE process using the STOAT simulation program. In particular, we attempted to improve nitrification rate even at lower water temperatures.Results and Discussion : As a result, more than 93% ammonia was nitrificated when the water temperature was above 20℃, and a lower reduction rate of ammonia was observed when the temperature was below 15℃. Simulations applying three process variables (MLSS, DO concentration, and RAS) were carried out once or several times to increase nitrogen removal efficiency at 10℃, and the most efficient variable was ‘RAS increase’(55% reduction of ammonia).Conclusions : For more efficient nitrification rate, simultaneous increases in RAS and DO were required. In this case, the ammonia concentration in the effluent dropped by 61.4% and it was desirable to increase the MLSS return volume for T-N concentration reduction.

scholarly journals Interaction between Biological Nitrogen Removal Processes and Operating Parameters: A Review

2020 ◽  
Vol 12 (4) ◽  
pp. 757-774
Author(s):  
M. S. I. Mozumder ◽  
M. D. Hossain
Keyword(s):  
Nitrogen Removal ◽  
Culture Medium ◽  
Human Life ◽  
Ammonia Concentration ◽  
Optimum Operating ◽  
Operating Parameters ◽  
Ammonium Oxidation ◽  
Advantages And Disadvantages ◽  
Removal Processes ◽  
Removal Technique

Nitrogen, mostly in the form of ammonia or nitrate containing wastewater deteriorated the water quality which simultaneously affects environment, plants, animals and human life. A number of researchers nowadays are conducting research to find out efficient and cost effective nitrogen removal technique along with optimum operating parameters. It is very important to uncover the optimum range of each parameter. In this study, it was winnowed to elicit the optimum operating ranges of dissolved oxygen concentration, temperature, pH, free ammonia concentration, nitrate concentration and culture medium. The nitrogen removal techniques were compared, evaluated considering advantages and disadvantages of them. Partial nitrification combined with anaerobic ammonium oxidation was found most prospective nitrogen removal technique for wastewater treatment compare to other techniques (conventional nitrification-denitrification over nitrate/nitrite, anammox, SND etc.) due to less oxygen consumption (62.5 % less), less sludge production, no carbon requirement, single reactor used and energy efficiency. SND process was more economical due to faster consumption of ammonia, nitrite and nitrate. There was various culture mediums which had a favorable or detrimental effect on specific nitrogen removal processes. However for desired bacteria culture for specific application, suitable culture medium needs to be selected considering the optimal operating parameters for microbial growth.

Intermittent Aeration for Nitrogen Removal in Small Oxidation Ditches

1990 ◽  
Vol 22 (3-4) ◽  
pp. 131-138 ◽  
Author(s):  
Hiroyuki Araki ◽  
Kenichi Koga ◽  
Katsuto Inomae ◽  
Tetsuya Kusuda ◽  
Youichi Awaya
Keyword(s):  
Nitrogen Removal ◽  
Cycle Time ◽  
Test Plant ◽  
Nitrification Rate ◽  
Oxidation Ditch ◽  
Intermittent Aeration ◽  
Tank Model ◽  
Scale Test ◽  
Total Nitrogen Removal ◽  
Removal Processes

An intermittent aeration method is available for nitrogen removal in a small oxidation ditch. The purpose of this study is to establish a basis for design and operation of the oxidation ditch with the intermittent aeration method. Discussions on the essential process parameters depending on cycle time tc, aerobic period ta, specific nitrification rate vn and specific denitrification rate vd were carried out by using a continuous-flow stirred-tank model. It is shown theoretically that an optimum range of the aerobic time ratio (ta/tc) for nitrogen removal exists in the region of 1/v n* to 1-1/vd*. From evaluating an amount of leaking nitrogen in the intermittent aeration, the cycle time is proved to be minimized. Experiments in a full scale test plant were conducted to affirm the validity of the proposed basis. It is confirmed that the total nitrogen removal efficiency of 90% is achieved and the estimated removal efficiencies by this basis agree well with the experimental data. The newly proposed basis and parameters for nitrogen removal using the intermittent aeration method are available for not only an oxidation ditch but also other nitrogen removal processes by single sludge systems.

Operation with biological nutrient removal with stable nitrification and control of filamentous growth

1998 ◽  
Vol 37 (4-5) ◽  
pp. 549-554 ◽  
Author(s):  
Maria Rothman
Keyword(s):  
Nitrogen Removal ◽  
Nutrient Removal ◽  
Suspended Solids ◽  
Treatment Plant ◽  
Filamentous Growth ◽  
Biological Nutrient Removal ◽  
Nitrification Rate ◽  
Do Concentration ◽  
And Control ◽  
Process Strategy

Bromma WWTP is the second largest wastewater treatment plant in Stockholm, Sweden. To meet new regulations regarding nitrogen removal the plant needs to be operated with nitrogen removal all year round. In previous years, severe bulking problems during the winter have made it impossible to maintain nitrification during colder temperatures. Microscopic examination of the activated sludge has increased the understanding of bulking. The bulking is mainly due to excessive growth of filamentous organisms, mainly Microthrix parvicella. By operating the plant with a high F/M ratio and decreasing the F/M ratio when filamentous growth occurs, excessive growth of these organisms can be avoided. The nitrification rate is optimized by adjusting the concentration of mixed liquid suspended solids in the tanks so that the nitrification is complete and by operating the tanks at a DO concentration of 4 mg/l. By this process strategy it is now possible to operate the plant with nitrification all year round.

Preliminary assessment of a shortcut in nitrogen removal from wastewater

1986 ◽  
Vol 13 (6) ◽  
pp. 600-605 ◽  
Author(s):  
O. Turk ◽  
D. S. Mavinic
Keyword(s):  
Nitrogen Removal ◽  
Oxygen Demand ◽  
Ammonia Concentration ◽  
Free Ammonia ◽  
Nitrite Reduction ◽  
Nitrification Rate ◽  
Nitrite Accumulation ◽  
Nitrite Level ◽  
In Series ◽  
System 2

The objective of this long-term research project was to demonstrate the feasibility of removing nitrogen from highly nitrogenous wastewater by (a) blocking the nitrification process at the intermediary nitrite level through the action of free ammonia and (b) subsequently reducing the nitrite to nitrogen gas. The success of such a process could lead to substantial reductions in nitrogen removal costs.Two identical bench-scale activated sludge systems were operated for 147 days, in the initial phase. Each system was composed of four equal-sized, completely mixed cells in series. The free ammonia concentration was highest in the first cell of each system. It averaged 2 mg NH3-N/L in the first system and 5 mg NH3-N/L in the second. Nitrite buildup, in excess of 80% of the oxidized nitrogen present, was induced and sustained for around 2 months in all cells of the second system, after which time a steady decline occurred. Nitrite buildup could not be sustained in the first system. Average chemical oxygen demand (COD) for nitrite reduction was 40% lower than that for nitrate reduction. The nitrification rate for the ammonia oxidizers was similar for both systems. The presence of up to 100 mg [Formula: see text] nitrite in system 2 caused no discernible inhibition. Subsequent runs proved that nitrite accumulation could not be sustained indefinitely, owing to acclimation to free ammonia levels as high as 22 mg NH3-N/L. Periodic resting and flushing may be required; further research is being pursued along these lines. Key words: biological treatment, denitrification, nitrification, nitrite, nitrogen removal, nitrogenous wastewater.

Relationships between nitrogen removal processes and functional microorganisms in the rhizosphere soil in a horizontal surface flow constructed wetland

2019 ◽  
Vol 70 (11) ◽  
pp. 1603 ◽  
Author(s):  
Yinuo Zhu ◽  
Jing Li ◽  
Zhangjie Cai ◽  
Wei Li ◽  
Yinru Lei ◽  
...  
Keyword(s):  
Nitrogen Removal ◽  
Constructed Wetland ◽  
Rhizosphere Soil ◽  
C:N Ratio ◽  
Surface Flow ◽  
Horizontal Surface ◽  
Nitrification Rate ◽  
Nirs Gene ◽  
Potential Nitrification ◽  
Removal Processes

Plant species could significantly affect the nitrogen removal processes mediated by microorganisms in constructed wetlands. However, the links between nitrogen removal processes in the rhizosphere and the related functional microorganisms in a horizontal surface flow constructed wetland in winter remain poorly understood. In this study we collected 24 rhizosphere soils from Typha orientalis and Phragmites australis to evaluate potential nitrogen removal activities, namely the potential nitrification rate (PNR) and denitrification enzyme activity (DEA), and their relationship with functional genes (i.e. nitrate reductase, nirS, and ammonia mono-oxygenase, amoA, of ammonia-oxidising archaea, AOA, and ammonia-oxidising bacteria, AOB) in denitrifiers and nitrifiers in winter. DEA and PNR were significantly higher in the rhizosphere soil of T. orientalis than P. australis, which was due to the higher abundance of nitrifiers and denitrifiers in the rhizosphere of T. orientalis. AOB were the major predictor of PNR in rhizosphere soil of T. orientalis, whereas AOA were more important for P. australis. In addition, denitrifiers containing the nirS gene were found to be the main drivers of DEA, and AOA and AOB also contributed to the denitrification process in the rhizosphere soil of both plants. Furthermore, the abundance of nitrifiers was significantly affected by the C:N ratio, soil organic matter and moisture, whereas the abundance of denitrifiers was affected by soil moisture and pH.

Nitrogen Removal with Nitrification and Denitrification via Nitrite

2014 ◽  
Vol 908 ◽  
pp. 175-178
Author(s):  
Jing Xiao ◽  
Jin Hua Tang
Keyword(s):  
Carbon Source ◽  
Nitrogen Removal ◽  
Ammonia Concentration ◽  
Free Ammonia ◽  
Partial Nitrification ◽  
High Ammonia ◽  
Future Challenges ◽  
Do Concentration ◽  
Nitrification And Denitrification ◽  
Biological Nitrification

Biological nitrification and denitrification via nitrite pathway is technically feasible and economically favorable, especially when wastewater with high ammonium concentrations or low C/N ratios is treated. Therefore, it has attracted more and more attention. It is very important to maintain partial nitrification of ammonium to nitrite. In this paper, the factors that influence operation and efficiency of nitrification and denitrification via nitrite are discussed, including DO concentration, carbon source, aeration pattern, PH, temperature and high free ammonia. High ammonia concentration and temperature are prone to accomplish of short-cut nitrification and denitrification, but limit application in practice. Finally, the review discussed the future challenges for application of short-cut nitrification and denitrification.

CHARACTERISATION OF THE NITRIFICATION PROCESS FOR DESIGN PURPOSES

1994 ◽  
Vol 30 (4) ◽  
pp. 47-56 ◽  
Author(s):  
O. Sinkjær ◽  
L. Yndgaard ◽  
P. Harremoës ◽  
J. L. Hansen
Keyword(s):  
Kinetic Theory ◽  
Nitrification Rate ◽  
Experimental Basis ◽  
Batch Tests ◽  
Mode Of Operation ◽  
Nitrification Process ◽  
Aerobic Reactor ◽  
The City ◽  
Specific Evaluation ◽  
Aerobic Sludge

Pilot plant experiments have been performed over a period of four years in order to establish an experimental basis for the upgrading of the treatment plants of the city of Copenhagen to nitrogen removal. The design chosen is based on the alternating mode of operation. Nitrification rates have been determined in batch tests on activated sludge extracted from the pilot plants and through the measuring of transient concentrations during the alternating mode of operation in the aerobic reactor. The data have been nonnalised to standard conditions by correcting them according to the kinetic theory. By monitoring the normalised nitrification rate it could be established that the nitrification process was occasionally inhibited. The aerobic sludge age required to maintain nitrification has been estimated. A specific evaluation has been made of the sensitivity of the required sludge age to the oxygen concentration and temperature.

Nitrogen Reduction – Volume Demand

1992 ◽  
Vol 25 (4-5) ◽  
pp. 233-240
Author(s):  
T. Palmgren
Keyword(s):  
Suspended Solids ◽  
Age Factors ◽  
Reduction Rate ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Aeration Tank ◽  
Nitrogen Reduction ◽  
Solids Concentration ◽  
Yearly Average ◽  
Nitrification Process

Due to the slow growth of nitrification bacteria at low temperatures, nitrogen reduction normally requires long hydraulic retention time during winter. Important for the nitrification process is the aerated sludge age. Factors influencing the sludge age are aerated volume, mixed liquor suspended solids concentration, organic loading and sludge yield. In an existing plant you cannot easily expand the volume and the load is difficult to decrease. But the suspended solids concentration can be increased by running the biological step with the contact stabilisation process. At the Käppala Association sewage treatment plant in Lidingö just outside Stockholm, one of the six aeration tanks has been reconstructed for full scale nitrogen removal experiments. In this tank the old aeration system has been replaced with rubber membrane diffusers. Further more there are several zones separated by walls in the tank. The tank can thereby be run with great flexibility. By running it with the contact stabilisation process, the sludge age has been improved by a factor between 1.5 and 2 and thereby it succeeds in keeping the nitrification bacteria in the system even during snow melting. At temperatures of about 9 °C and hydraulic retention times of less than 3 hours in the contact zone there has been a nitrification degree of up to 50 to 60 %. The experiment was conducted with a stabilisation zone of up to half the total volume of the aeration tank. The main purpose for the experiments during the winter seasons was to improve nitrification. Keeping the nitrifiers in the system had been a crucial problem during previous years. When the nitrifiers were lost with an increased flow and decreased temperature the nitrification process didn't restart until the temperature was increased and the load decreased. Usually this didn't occur until the middle of the summer meaning a loss of nitrification for up to six months. In Sweden there is a goal set for 50 % nitrogen reduction for the plants in the Stockholm region. At Käppala we manage to keep 60 to 70 % nitrogen reduction during the warm season, that is from July to December. If we can keep up the nitrification the whole year we can achieve 50 % as a yearly average under normal conditions even though we can't keep the nitrogen reduction rate as high during the cold season.

Nitrogen removal from wastewater treatment lagoons

1999 ◽  
Vol 39 (6) ◽  
pp. 191-198 ◽  
Author(s):  
Timothy J. Hurse ◽  
Michael A. Connor
Keyword(s):  
Wastewater Treatment ◽  
Nitrogen Removal ◽  
Treatment Plant ◽  
Ammonia Removal ◽  
Contour Plot ◽  
Removal Mechanism ◽  
Dissolved Oxygen Concentration ◽  
Physical Processes ◽  
Contour Plots ◽  
Removal Processes

In an attempt to gain a better understanding of ammonia and nitrogen removal processes in multi-pond wastewater treatment lagoons, an analysis was carried out of data obtained during regular monitoring of Lagoon 115E at the Western Treatment Plant in Melbourne. To do this, a contour plot approach was developed that enables the data to be displayed as a function of pond number and date. Superimposition of contour plots for different parameters enabled the dependence of ammonia and nitrogen removal rates on various lagoon characteristics to be readily assessed. The importance of nitrification as an ammonia removal mechanism was confirmed. Temperature, dissolved oxygen concentration and algal concentration all had a significant influence on whether or not sizeable nitrifier populations developed and persisted in lagoon waters. The analysis made it evident that a better understanding of microbial, chemical and physical processes in lagoons is needed before their nitrogen removal capabilities can be predicted with confidence.

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