Study on Shortcut and Simultaneous Nitrification and Denitrification under Low Temperatures

2012 ◽  
Vol 610-613 ◽  
pp. 2047-2052
Author(s):  
Jin Xiang Fu ◽  
Xin Chun Zhang ◽  
Peng Fei Yu
Keyword(s):  
Low Temperature ◽  
Adverse Effects ◽  
Treatment Effect ◽  
Low Temperatures ◽  
Accumulation Rate ◽  
Heating Process ◽  
Nitrite Accumulation ◽  
Simultaneous Nitrification And Denitrification ◽  
Nitrification And Denitrification ◽  
The Impact

This paper studies the impact of cooling and warming on shortcut and simultaneous nitrification and denitrification under low temperature. The results show that the effluent concentration of NH4+-N and TN gradually increased, the nitrite accumulation rate decreased when DO was 0.3~0.5 mg•L-1, sludge return ratio was 300%, PH was 7.5~8.5, temperature dropped from 15 °Cto 8°C. From 10°C to 8°C in cooling, the average nitrite accumulation rate was 58.17% in A (HRT=24h) reactor. During the system heating process, treatment effect of the system gradually changed for the better. From 12°C to 15°Cin heating process, the average nitrite accumulation rate was 74.39% in B (HRT=48h) reactor. The system treatment effect in B reactor was better by contrasting A and B reactors, therefore, we can increase HRT to reduce the adverse effects on the system due to the temperature decreases to enhance TN removal effect of system.

scholarly journals Evaluation of a novel low-carbon to nitrogen- and temperature-tolerant simultaneously nitrifying–denitrifying bacterium and its use in the treatment of river water

RSC Advances ◽  
2018 ◽  
Vol 8 (48) ◽  
pp. 27417-27422 ◽  
Author(s):  
Peng Jin ◽  
Yinyan Chen ◽  
Zhanwang Zheng ◽  
Qizhen Du
Keyword(s):  
Low Temperature ◽  
River Water ◽  
Removal Efficiency ◽  
Nitrogen Removal ◽  
Simultaneous Nitrification And Denitrification ◽  
Low Carbon ◽  
High Nitrogen ◽  
Denitrifying Bacterium ◽  
Nitrification And Denitrification

A novel simultaneous nitrification and denitrification Klebsiella sp. exhibits high nitrogen removal efficiency under low-temperature and low C/N wastewater.

Deployment performance of shape memory polymer composite hinges at low temperature

2019 ◽  
Vol 30 (17) ◽  
pp. 2625-2638 ◽  
Author(s):  
Van Luong Le ◽  
Vinh Tung Le ◽  
Nam Seo Goo
Keyword(s):  
Low Temperature ◽  
Shape Memory ◽  
Polymer Composite ◽  
Room Temperature ◽  
Shape Memory Polymer ◽  
Heating Element ◽  
Heating Process ◽  
Space Applications ◽  
Design Modification ◽  
The Impact

Shape memory polymer composite hinges, adapted for possible space applications, were successfully designed and fabricated, and performance tests at room temperature confirmed their full recoverability in our previous studies. Since shape memory polymer composite hinges are intended for space applications, they should be able to operate at low temperature. Even though the deployment of the hinge at room temperature triggered by the stimulation of a heating element has been quite promising, a suitable design for a shape memory polymer composite hinge with a heating element is more important at low temperatures because shape memory polymer composite hinges lose much heat to the environment. The recoverability of shape memory polymer composite hinges and the impact of the heating element design on the deployment time at low temperature are brought to light in this article. A shape memory polymer composite hinge with an attached heating element was fabricated as in our previous studies. The necessary power and supply power for deployment of the shape memory polymer composite hinge at a low temperature of –10°C were calculated, and a finite element analysis for the heating process was performed with the supply power. A folding and deployment test of the shape memory polymer composite hinge at –10°C was performed to show its shape recoverability. However, the shape memory polymer composite hinge did not deploy to its original shape. To determine the reason, measurements of temperature distribution were done using an infrared camera and thermocouples. The results revealed that the low temperature along the two side edges of the shape memory polymer composite tape prevented full deployment of the shape memory polymer composite hinge, which also revealed the need for design modification. The folding and deployment test of our modified shape memory polymer composite hinge demonstrated a nearly full deployment.

scholarly journals Impacts of Low Temperatures on Wolbachia (Rickettsiales: Rickettsiaceae)-Infected Aedes aegypti (Diptera: Culicidae)

2020 ◽  
Vol 57 (5) ◽  
pp. 1567-1574 ◽  
Author(s):  
Meng-Jia Lau ◽  
Perran A Ross ◽  
Nancy M Endersby-Harshman ◽  
Ary A Hoffmann
Keyword(s):  
Life History ◽  
Low Temperature ◽  
Aedes Aegypti ◽  
Disease Transmission ◽  
Low Temperatures ◽  
Temperature Effects ◽  
Life Stage ◽  
Temperature Cycles ◽  
The Impact ◽  
Wolbachia Density

Abstract In recent decades, the occurrence and distribution of arboviral diseases transmitted by Aedes aegypti mosquitoes has increased. In a new control strategy, populations of mosquitoes infected with Wolbachia are being released to replace existing populations and suppress arboviral disease transmission. The success of this strategy can be affected by high temperature exposure, but the impact of low temperatures on Wolbachia-infected Ae. aegypti is unclear, even though low temperatures restrict the abundance and distribution of this species. In this study, we considered low temperature cycles relevant to the spring season that are close to the distribution limits of Ae. aegypti, and tested the effects of these temperature cycles on Ae. aegypti, Wolbachia strains wMel and wAlbB, and Wolbachia phage WO. Low temperatures influenced Ae. aegypti life-history traits, including pupation, adult eclosion, and fertility. The Wolbachia-infected mosquitoes, especially wAlbB, performed better than uninfected mosquitoes. Temperature shift experiments revealed that low temperature effects on life history and Wolbachia density depended on the life stage of exposure. Wolbachia density was suppressed at low temperatures but densities recovered with adult age. In wMel Wolbachia there were no low temperature effects specific to Wolbachia phage WO. The findings suggest that Wolbachia-infected Ae. aegypti are not adversely affected by low temperatures, indicating that the Wolbachia replacement strategy is suitable for areas experiencing cool temperatures seasonally.

Effect on Denitrification Efficiency in Alternating Process at Different C/N Ratio

2014 ◽  
Vol 1030-1032 ◽  
pp. 442-445
Author(s):  
Chun Di Gao ◽  
Wei Xiao Wang ◽  
Shi Xin Fan ◽  
Hao Li ◽  
Er Long Jiao
Keyword(s):  
Accumulation Rate ◽  
Removal Rate ◽  
Oxygen Demand ◽  
Ammonia Nitrogen ◽  
Partial Nitrification ◽  
Biological Nitrogen Removal ◽  
Nitrite Accumulation ◽  
High Level ◽  
Biological Nitrogen ◽  
The Impact

Nitrification-denitrification biological nitrogen removal process has become the hotspot for the wastewater. During carbon/nitrogen (C/N) ratio was 1.16, 2.25, 4.07 and 6.20, the change of denitrification efficiency and the impact on the partial nitrification/denitrification was investigated. The results showed that removal rate of ammonia nitrogen was maintained in the high level, and was stable above 98% after C/N ratio higher than 1.16. With C/N ratio increased, the removal rate of chemical oxygen demand was increased about 20%, total nitrogen was increased from 54.9% to 84.6%. Simultaneously, after C/N ratio was higher than 4.07, the concentration of effluent TN was below 15 mg/L. Nitrite accumulation rate was maintained above 95%, the effect on partial nitrification was good, and the concentration of effluent nitrate was nearly 0, the best ratio of the C/N ratio was 4.07.

The impact of low temperatures in controlling the geographical distribution of plants

1990 ◽  
Vol 326 (1237) ◽  
pp. 585-593 ◽  
Keyword(s):  
Seed Germination ◽  
Low Temperature ◽  
Low Temperatures ◽  
Marked Change ◽  
Tilia Cordata ◽  
Natural Range ◽  
Distribution Limits ◽  
The Impact ◽  
Temperature Responses

The distribution limits of three species, in the British Isles are discussed. For Verbena officinalis and Tilia cordata low temperatures are shown to influence distribution, by limiting the capacity either to flower or to fertilize ovules, respectively. In the case of Umbilicus rupestris , a long-term transplant population beyond the natural geographical limit of the species has evolved new low-temperature responses of seed germination and winter survival. The effect is a marked change of phenology, compared with populations of the species within its natural range, which enhances the capacity of the population to survive in a colder environment.

Impact of SRT on Simultaneous Nitrification and Denitrification in a Carrousel Oxidation Ditch for Sewage Treatment

2012 ◽  
Vol 550-553 ◽  
pp. 2104-2107
Author(s):  
Yi Ming Chen
Keyword(s):  
Sewage Treatment ◽  
Pilot Scale ◽  
Ammonia Nitrogen ◽  
Municipal Sewage ◽  
Simultaneous Nitrification And Denitrification ◽  
Oxidation Ditch ◽  
Treatment Efficiency ◽  
Nitrification And Denitrification ◽  
Carrousel Oxidation Ditch ◽  
The Impact

The impact of SRT on simultaneous nitrification and denitrification (SND) in the Carrousel Oxidation Ditch was carried out based on pilot-scale to treat low COD/TN municipal sewage. The impact factor, sludge retention time (SRT), was investigated on the occurrence of SND. The experiment results showed that in the oxygen-deficient environment whose DO was 0.3 mg/L, R of 50%, MLSS of 4000 mg/L, the treatment efficiency achieved the best with SRT of 20 d, the COD, ammonia nitrogen, total nitrogen (TN) of effluent were lower than 32 mg/L, 5 mg/L, 13 mg/L, respectively, which was observed efficient phenomenon of SND. Overall, these results demonstrated that the Carrousel Oxidation Ditch with the occurrence of SND could have the potential to treat low C/N sewage.

scholarly journals Optimisation of Direct Battery Thermal Management for EVs Operating in Low-Temperature Climates

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5980 ◽  
Author(s):  
James Jeffs ◽  
Truong Quang Dinh ◽  
Widanalage Dhammika Widanage ◽  
Andrew McGordon ◽  
Alessandro Picarelli
Keyword(s):  
Low Temperature ◽  
Ambient Temperature ◽  
Thermal Management ◽  
Electric Vehicles ◽  
Low Temperatures ◽  
Air Conditioning ◽  
Lithium Ion ◽  
Battery Thermal Management ◽  
Temperature Performance ◽  
The Impact

Electric vehicles (EVs) experience a range reduction at low temperatures caused by the impact of cabin heating and a reduction in lithium ion performance. Heat pump equipped vehicles have been shown to reduce heating ventilation and air conditioning (HVAC) consumption and improve low ambient temperature range. Heating the electric battery, to improve its low temperature performance, leads to a reduction in heat availability for the cabin. In this paper, dynamic programming is used to find the optimal battery heating trajectory which can optimise the vehicle’s control for either cabin comfort or battery performance and, therefore, range. Using the strategy proposed in this research, a 6.2% increase in range compared to no battery heating and 5.5% increase in thermal comfort compared to full battery heating was achieved at an ambient temperature at −7 °C.

N2O emission in short-cut simultaneous nitrification and denitrification process: dynamic emission characteristics and succession of ammonia-oxidizing bacteria

2014 ◽  
Vol 69 (12) ◽  
pp. 2541-2547 ◽  
Author(s):  
Yingyan Yan ◽  
Ping Li ◽  
Jinhua Wu ◽  
Nengwu Zhu ◽  
Pingxiao Wu ◽  
...  
Keyword(s):  
Removal Rate ◽  
N2o Emission ◽  
Nitrite Accumulation ◽  
Ammonia Oxidizing Bacteria ◽  
Simultaneous Nitrification And Denitrification ◽  
Process Dynamic ◽  
Nitrifier Denitrification ◽  
Important Pathway ◽  
Nitrification And Denitrification ◽  
Denitrification Process

A sequencing batch airlift reactor was used to investigate the characteristics of nitrous oxide (N2O) emission and the succession of an ammonia-oxidizing bacteria (AOB) community. The bioreactor could successfully switch from the complete simultaneous nitrification and denitrification (SND) process to the short-cut SND process by increasing the influent pH from 7.0–7.3 to 8.0–8.3. The results obtained showed that, compared with the complete SND process, the TN removal rate and SND efficiency were improved in the short-cut SND process by approximately 13 and 11%, respectively, while the amount of N2O emission was nearly three times larger than that in the complete SND process. The N2O emission was closely associated to nitrite accumulation. Analysis of the AOB microbial community showed that nitrifier denitrification by Nitrosomonas-like AOB could be an important pathway for the enhancement of N2O emission in the short-cut SND process.

scholarly journals Investigation on the Effect of Low Temperature on Impact Properties of Ti-6Al-4V Titanium Alloy

2020 ◽  
Author(s):  
wei zhao ◽  
WenJia Su ◽  
Liang Li ◽  
Ding Fang ◽  
Ni Chen
Keyword(s):  
Titanium Alloy ◽  
Low Temperature ◽  
Low Temperatures ◽  
Research Result ◽  
Cutting Mechanism ◽  
Impact Properties ◽  
Fiber Area ◽  
The Impact ◽  
Cryogenic Cutting ◽  
Radiation Area

Abstract Cryogenic cutting is becoming an attractive machining method for difficult-to-cut materials. However, it’s very difficult to analyze directly their cutting mechanism at low temperature. In order to better understand the various physical phenomena in the cryogenic cutting of titanium alloy, the Charpy impact test of Ti-6Al-4V titanium alloy at low temperatures (as low as -196 °C) was undertaken in this work. The Charpy absorbed energy of Ti-6Al-4V titanium alloy at low temperatures was investigated firstly. Then, by observing the microscopic and macroscopic morphology of the fracture, the impact properties and fracture modes of Ti-6Al-4V titanium alloy at low temperatures were analyzed. It was found that the impact toughness of Ti-6Al-4V titanium alloy reduces when the temperature decreases from 20 °C to -196 °C, and the fracture appears a tendency to become brittle. Meanwhile, three kinds of areas, i.e. shear lip area, fiber area, and radiation area, were found on the fracture morphology at each temperature. Those areas correspond to the shear fracture zone, crack initiation zone, and crack extension zone, respectively. With the decrease in temperature, the proportion of fiber area decreases, and the radiation area appears and increases gradually. However, fiber areas were still observed on the macroscopic morphology of the fracture under − 196 °C, which suggests that Ti-6Al-4V titanium alloy still has the ability to deform plastically at such low temperatures. The research result in this work provide a fundamental support for analyzing the cutting mechanism of Ti-6Al-4V titanium alloy at low temperatures.

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