A New Sensing Technique for Optimum Sludge Conditioning for Waste Sludge Dewatering

A new sensing technique using a Hot-Film sensor for determining the optimum polymer dosage for sludge dewatering has been developed. Correlations between the behavior of the Hot-Film sensor and dewaterability of sewage and night soil sludge were investigated. The results of the study revealed the following: the Hot-Film sensor values depended on the filtrate characteristics related to the sludge dewaterability which is measured by the filterability of the conditioned sludge and by the moisture content of the dewatered sludge cake; the optimum polymer dosage for sludge dewatering corresponded with the minimum output value on the characteristics curve of the Hot-Film sensor. This paper describes the observations of the measurement test by the Hot-Film sensor as well as the results of the laboratory test of sludge dewatering for optimum sludge conditioning.

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Localization of Flow Separation and Transition Over a Pitching NACA0012 Airfoil at Transitional Reynolds Numbers Using Hot-Films

Journal of Fluids Engineering ◽

10.1115/1.4031008 ◽

2015 ◽

Vol 137 (12) ◽

Cited By ~ 12

Author(s):

Allison Poels ◽

Daniel Rudmin ◽

Azemi Benaissa ◽

Dominique Poirel

Keyword(s):

Reynolds Numbers ◽

Correlation Technique ◽

Film Sensor ◽

Pitching Airfoil ◽

Eddy Simulation ◽

Naca0012 Airfoil ◽

Large Eddy ◽

Sensor Signals ◽

Hot Film ◽

Hot Film Sensor

Separation and transition of flow over a pitching airfoil at transitional Reynolds Number are analyzed experimentally. The method is based on a windowed correlation between hot-film sensor signals taken simultaneously or synchronized based on the airfoil pitch angle. A comparison with large eddy simulation (LES) simulation obtained in the same conditions is presented and discussed. Our results agree very well with the LES data for the separation location during the pitch-up. For the pitch-down, the results show differences with the LES. However, when the LES data are analyzed with the same correlation technique, the results are in a better agreement.

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Study on the effect of chitosan conditioning on sludge dewatering

Water Science & Technology ◽

10.2166/wst.2019.073 ◽

2019 ◽

Vol 79 (3) ◽

pp. 501-509 ◽

Cited By ~ 1

Author(s):

Jin Zhang ◽

Qing Hu ◽

Jie Lu ◽

Shuang Lin

Keyword(s):

Moisture Content ◽

Extracellular Polymeric Substances ◽

Waste Water Treatment ◽

Sewage Treatment ◽

Organic Polymer ◽

Sludge Dewatering ◽

Sludge Treatment ◽

Residual Sludge ◽

Sludge Cake ◽

Polymer Flocculant

Abstract The difficulty of residual sludge dehydration is the major problem in sewage treatment. The reduction of moisture content in sludge can reduce the sludge volume significantly and is conducive to the subsequent disposal of sludge. As an organic polymer flocculant, chitosan (CTS) is widely used in water and waste water treatment. In this study, CTS was used in sludge treatment to improve the sedimentation and dehydration properties of sludge. When treated with CTS, the moisture content of sludge cake decreased from 85.9% to 83.0%, the SV30 decreased to about 1/2, and the sludge volume reduced to 82.9%. Further analysis showed that the zeta potential (ζ-potential) of the sludge changed from negative value to positive value, and the D50 of the sludge was larger than that of the raw sludge. In addition, when the moisture content of the sludge cake was reduced to the lowest, the concentration of extracellular polymeric substances (EPS) and SCOD was the largest and the |ζ| decreased to the lowest. CTS improved the dehydration and sedimentation performance of sludge mainly by factors of electrical neutralization, adsorption bridging and dissolution of EPS.

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Unsteady heat film transfer from a thick hot-film sensor

Journal of Thermophysics and Heat Transfer ◽

10.2514/3.615 ◽

1994 ◽

Vol 8 (4) ◽

pp. 797-799 ◽

Cited By ~ 4

Author(s):

Chong H. Park ◽

Kevin D. Cole

Keyword(s):

Film Sensor ◽

Film Transfer ◽

Hot Film ◽

Hot Film Sensor

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Carbon Nanotube Thermal Probe Using Platinum Nano Hot-Film

ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer, Volume 2 ◽

10.1115/mnhmt2009-18356 ◽

2009 ◽

Author(s):

Koji Takahashi ◽

Jun Hirotani ◽

Satoshi Kai ◽

Tatsuya Ikuta

Keyword(s):

Carbon Nanotube ◽

Contact Point ◽

Atmospheric Condition ◽

Thermal Probe ◽

Film Sensor ◽

Thermal Sensing ◽

Water Absorption Effect ◽

Hot Film ◽

Air Conduction ◽

Hot Film Sensor

This paper reports on a thermal probe using a carbon nanotube (CNT) on a platinum hot-film. CNT probe is expected to breakthrough the limitations of the existing ones owing to its unique characteristics but no practical thermal device has been fabricated yet. In order to explore the mechanisms of heating and measuring the smaller region than 10nm, we applied our recently developed sensor coupled with CNT, which consists of a suspended platinum film of 40nm × 500nm × 10micrometer. The principle of this probe as heater and sensor is explained, based on one dimensional heat conduction. Fabrication process using MEMS technique is also introduced, especially for a couple of critical techniques. One is to fabricate the nano sensor on an edge of the sensor substrate. The other is to bond a CNT on the suspended hot-film sensor. A CNT thermal probe using a multi-walled CNT of 70nm diameter and ca. 10 micrometers length is successfully fabricated. Its performances are tested in vacuum environment as to eliminate the presence of in-air conduction effect and water absorption effect around the contact point, which work for heat transport dominantly in atmospheric condition and degrade the spatial resolution. Our CNT probe showed a clear and reliable signal in vacuum and its sensitivity available for nanoscale thermal sensing and heating is confirmed.

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215 Development of micro-fabricated hot-film sensor by MEMS and study on its validation of the wall shear stress fluctuation measurement

The Proceedings of Conference of Tokai Branch ◽

10.1299/jsmetokai.2014.63._215-1_ ◽

2014 ◽

Vol 2014.63 (0) ◽

pp. _215-1_-_215-2_

Author(s):

Takuya SAWADA ◽

Osamu TERASHIMA ◽

Yasuhiko SAKAI ◽

Kouji Nagata ◽

Mitsuhiro SHIKIDA ◽

...

Keyword(s):

Shear Stress ◽

Wall Shear Stress ◽

Film Sensor ◽

Stress Fluctuation ◽

Wall Shear ◽

Hot Film ◽

Fluctuation Measurement ◽

Hot Film Sensor

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Wall shear stress hot film sensor for use in gases

Journal of Physics Conference Series ◽

10.1088/1742-6596/296/1/012002 ◽

2011 ◽

Vol 296 ◽

pp. 012002 ◽

Cited By ~ 2

Author(s):

O D Osorio ◽

N Silin

Keyword(s):

Shear Stress ◽

Wall Shear Stress ◽

Film Sensor ◽

Wall Shear ◽

Hot Film ◽

Hot Film Sensor

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A Technique for the Measurement of Wall Shear Stress Based on Micro Fabricated Hot-Film Sensor

Volume 7B: Fluids Engineering Systems and Technologies ◽

10.1115/imece2013-63091 ◽

2013 ◽

Author(s):

Takuya Sawada ◽

Osamu Terashima ◽

Yasuhiko Sakai ◽

Kouji Nagata ◽

Mitsuhiro Shikida ◽

...

Keyword(s):

Shear Stress ◽

Wall Shear Stress ◽

Turbulent Flows ◽

Temporal Resolution ◽

Large Scale ◽

High Temporal Resolution ◽

Film Sensor ◽

Wall Shear ◽

Hot Film ◽

Hot Film Sensor

The objective of this study is to establish a technique for accurately measuring the wall shear stress in turbulent flows using a micro-fabricated hot-film sensor. Previously, we developed a hot-film sensor with a flexible polyimide-film substrate. This sensor can be attached to curved walls and be used in various situations. Furthermore, the sensor has a 20-μm-wide, heated thin metal film. However, the temporal resolution of this hot-film sensor is not very high owing to its substrate’s high heat capacity. Consequently, its performance is inadequate for measuring the wall shear stress “fluctuations” in turbulent flows. Therefore, we have developed another type of hot-film sensor in which the substrate is replaced with silicon, and a cavity has been introduced under the hot-film for reducing heat loss from the sensor and achieving high temporal resolution. Furthermore, for improving the sensor’s spatial resolution, the width of the hot-film is decreased to 10 μm. The structure of the hot-film’s pattern and the flow-detection mechanism are similar to those of the previous sensor. Experimental results show that new hot-film sensor works as expected and has better temporal resolution than the previous hot-film sensor. As future work, we will measure the wall shear stress for a turbulent wall-jet and discuss the relationship between a large-scale coherent vortex structure and wall shear stress based on data obtained using the new hot-film sensor.

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