Effect of operational cycle time length on nitrogen removal in an alternating oxidation ditch system

2011 ◽  
Vol 34 (5) ◽  
pp. 597-606 ◽  
Author(s):  
I. D. Mantziaras ◽  
A. Stamou ◽  
A. Katsiri
Keyword(s):  
Nitrogen Removal ◽  
Cycle Time ◽  
Oxidation Ditch ◽  
Time Length ◽  
Operational Cycle

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.

scholarly journals Influence of bifurcation on thinning, productivity and harvester production costs of Pinus taeda L.

2020 ◽  
pp. 1259-1263
Author(s):  
Carlos Cézar Cavassin Diniz ◽  
Romano Timofeiczyk Junior ◽  
Renato Gonçalves Robert ◽  
Eduardo da Silva Lopes ◽  
João Carlos Garzel Leodoro da Silva ◽  
...  
Keyword(s):  
Pinus Taeda ◽  
Cycle Time ◽  
Production Costs ◽  
Total Production ◽  
Plantation Forest ◽  
Operating Cycle ◽  
Operational Cycle ◽  
Time And Motion ◽  
Motion Study ◽  
Pinus Taeda L

In this work, we present that how bifurcation in Pinus trees can influence productivity and harvester production costs. Our example draws from one harvesting machine that works in thinning operations in forest plantations of Pinus taeda L. in a small Brazilian forestry company. To get daily productivity, we use the machine’s system, which provides such daily information as total production. We also used a time and motion study to obtain the meantime to cut, delimb, and process the tree stem into logs. In this way, we separated the normal trees from the forked trees to get the operating cycle time of the machine and get the productivity to the two types of trees. The continuous timing method was used for this purpose. The results show an increase of up to 22.9% in the operational cycle time for cutting forked trees, resulting in reduction of productivity of 5.58 m³ for each hour worked. The production cost increased by 23.3% on operation of forked trees, as the machine took more time to perform the partial activities of the operational cycle. This study can help many companies and contractors to calculate the appropriate productivity and production harvest cost according to the type of tree stems from the plantation forest.

Enhanced nitrogen removal and energy saving of intermittent aeration-modified oxidation ditch process

2013 ◽  
Vol 52 (25-27) ◽  
pp. 4895-4903 ◽  
Author(s):  
Bo-Lin Li ◽  
Zhi Zhang ◽  
Ye Li ◽  
Meng-Ting Song ◽  
Chi Zhang
Keyword(s):  
Energy Saving ◽  
Nitrogen Removal ◽  
Oxidation Ditch ◽  
Intermittent Aeration

Biological Nitrogen Removal under Low Temperature in a Membrane Separation Bioreactor

1993 ◽  
Vol 28 (10) ◽  
pp. 325-333 ◽  
Author(s):  
C. Chiemchaisri ◽  
K. Yamamoto
Keyword(s):  
Low Temperature ◽  
Nitrogen Removal ◽  
Oxygen Transfer ◽  
Membrane Separation ◽  
Nitrifying Bacteria ◽  
Biological Nitrogen Removal ◽  
Nitrification Rate ◽  
Temperature Decrease ◽  
Operational Cycle ◽  
Biological Nitrogen

Biological nitrogen removal under low temperature in a membrane separation bioreactor for on-site domestic wastewater treatment was studied. The bioreactor was operated under intermittent aeration of a 180-minute operational cycle to achieve simultaneous nitrification and denitrification for nitrogen removal. During stepwise temperature decrease from 25°C to 5°C at every two weeks duration, nitrogen removal started to deteriorate as temperature dropped to 10°C. It decreased from more than 90% at 25°C to 20% at 5°C as a result of inhibition of nitrification at low temperature. However, increasing oxygen supply, i.e. increasing aeration time in operational cycle, could completely recover nitrification at 10°C. Nitrogen removal could be achieved by introducing non-aeration period after complete nitrification was obtained. Average nitrogen removal was 90 and 85% under 10 and 5°C respectively. The results indicated that sufficient oxygen transfer could be maintained in the membrane separation bioreactor even if the temperature was as low as 5°C. Analysis of respiratory quinone component of sludge suggested the decrease of strict aerobic bacteria percentage in mixed liquor during temperature decrease and increase of their percentage during the recovery of nitrification at 10°C. These changes could be related to the nitrification through the changes of oxygen transfer condition in the system. Insignificant difference of maximum volumetric nitrification rate obtained at 25 and 5°C probably suggests that there was not much difference in oxygen availability for nitrifying bacteria between both the temperatures once high and stable nitrogen removal was achieved.

Deposition pattern, effect on nitrogen removal and component analysis of deposited sludge in a carrousel oxidation ditch

2013 ◽  
Vol 52 (31-33) ◽  
pp. 6079-6087 ◽  
Author(s):  
He Li ◽  
Ji Fang-ying ◽  
Zhou Wei-wei ◽  
Xu Xuan ◽  
Chen Rui-hong ◽  
...  
Keyword(s):  
Nitrogen Removal ◽  
Component Analysis ◽  
Oxidation Ditch ◽  
Deposition Pattern ◽  
Pattern Effect ◽  
Carrousel Oxidation Ditch

Improvement of existing nightsoil treatment plant for nitrogen removal

2004 ◽  
Vol 49 (5-6) ◽  
pp. 273-279
Author(s):  
B.S. Lim ◽  
J.U. Kim ◽  
H.D. Park
Keyword(s):  
Nitrogen Removal ◽  
Removal Rate ◽  
Treatment Plant ◽  
Second Step ◽  
Aeration Tank ◽  
Oxidation Ditch ◽  
Treatment Efficiency ◽  
Operation And Maintenance ◽  
One Year ◽  
Efficiency Rate

This study was performed to increase the treatment efficiency and to reduce operation and maintenance costs of the existing nightsoil treatment plant. The existing nightsoil plant was not established by the nitrogen removal process, and was operated ineffectively with deterioration of treatment efficiency rate, and according to the demand of many operators, the expenses of operation and maintenance have become excessive. Modified plant has been changed through two steps. The first step, liquid decayed tank using closed oxidation ditch is operated to increase retention time only for nitrification. The second step, modified liquid decayed tank including anoxic tank is operated, it has an excellent nitrogen removal rate. In first step, when HRT was increased from 10 days to 13 days in liquid decayed tank including aeration tank using closed oxidation ditch, TN concentration of effluent appeared below 51 mg/l less than discharge limit, 60 mg/L. In second step, when anoxic tank and oxic tank were installed, HRT has been increased to 13 days and 26 days, respectively. Then average TN concentration of effluent was detected less than 13 mg/L for over one year. The simple process modified the existing two processes resulted in the reduction of costs for operation and maintenance in the personnel, chemical, and filter change sphere.

Reducing operational cycle time using smed technique

2017 ◽  
Vol 7 (1) ◽  
pp. 32
Author(s):  
Vibhuti Aditya Save
Keyword(s):  
Cycle Time ◽  
Operational Cycle

Evaluation of a novel oxidation ditch system for biological nitrogen and phosphorus removal from domestic sewage

2010 ◽  
Vol 62 (8) ◽  
pp. 1745-1754 ◽  
Author(s):  
X. Chen ◽  
T. Fujiwara ◽  
K. Ohtoshi ◽  
S. Inamori ◽  
K. Nakamachi ◽  
...  
Keyword(s):  
Nitrogen Removal ◽  
Phosphorus Removal ◽  
Domestic Sewage ◽  
Control Technology ◽  
Oxidation Ditch ◽  
Anoxic Zone ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Do Control ◽  
Biological Nitrogen

A novel oxidation ditch system using anaerobic tanks and innovative dual dissolved oxygen (DO) control technology is proposed for biological nitrogen and phosphorus removal from domestic sewage. A continuous bench-scale experiment running for more than 300 days was performed to evaluate the system. Monitoring and controlling the airflow and recirculation flow rate independently using DO values at two points along the ditch permitted maintenance of aerobic and anoxic zone ratios of around 0.30 and 0.50, respectively. The ability to optimize aerobic and anoxic zone ratios using the dual DO control technology meant that a total nitrogen removal efficiency of 83.2–92.9% could be maintained. This remarkable nitrogen removal performance minimized the nitrate recycle to anaerobic tanks inhibiting the phosphorus release. Hence, the total phosphorus removal efficiency was also improved and ranged within 72.6–88.0%. These results demonstrated that stabilization of the aerobic and anoxic zone ratio by dual DO control technology not only resulted in a marked improvement of nitrogen removal, but it also enhanced phosphorus removal.

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