scholarly journals Three decades of oxygen transfer tests in clean water in a pilot scale test tank with fine-bubble diffusers and the resulting conclusions for WWTP operation

2020 ◽  
Vol 15 (4) ◽  
pp. 910-920
Author(s):  
J. Behnisch ◽  
M. Schwarz ◽  
M. Wagner
Keyword(s):  
Oxygen Transfer ◽  
Cost Benefit Analysis ◽  
Cost Benefit ◽  
Pilot Scale ◽  
Transfer Efficiency ◽  
Clean Water ◽  
Test Tank ◽  
Fine Bubble ◽  
Oxygen Transfer Efficiency ◽  
Bubble Diffusers

Abstract We summarized the experience from three decades of oxygen transfer testing and aeration research at the Technical University of Darmstadt to validate the oxygen transfer efficiency of modern fine-bubble diffusers. A total of 306 oxygen transfer tests in clean water of 65 different fine-bubble diffusers, carried out in the same test tank under identical test conditions, were analysed and compared with previous results. As a result, we could show that the performance of fine-bubble aeration systems has increased by 17% over the last three decades. Therefore, modern well-designed and operated aeration systems can achieve specific standard oxygen transfer efficiency (SSOTE) values between 8.5 and 9.8% · m−1. Additionally, a comparison of various diffuser types and diffuser densities was done. Based on the new results, an exemplary cost/benefit analysis for a 100,000 PE WWTP shows the calculation of an optimized diffuser density with respect to investment and operating costs.

An assessment of oxygen transfer efficiency in a gas permeable hollow fibre membrane biological reactor

2010 ◽  
Vol 61 (5) ◽  
pp. 1165-1171 ◽  
Author(s):  
G. Soreanu ◽  
L. Lishman ◽  
S. Dunlop ◽  
H. Behmann ◽  
P. Seto
Keyword(s):  
Mass Transfer ◽  
Chemical Reaction ◽  
Oxygen Transfer ◽  
Membrane Surface ◽  
Treatment Plant ◽  
Hollow Fibre ◽  
Transfer Efficiency ◽  
Fine Bubble ◽  
Oxygen Transfer Efficiency ◽  
Bubble Diffusers

The clean water oxygen transfer efficiency (OTE) of a full scale non-porous hollow fibre gas permeable (GP) membrane (surface area of 500 m2) was evaluated at inlet air pressures of 1.2, 1.4, and 1.8 atm using two established testing methods. To form a basis of comparison with traditional aeration technologies, additional testing was done with conventional aerators (fine bubble and coarse bubble diffusers) replacing the GP membrane. OTE can be established based on the re-aeration of deoxygenated water or by monitoring the catalytic oxidation of a sodium sulphite (Na2SO3) solution. In this study, OTE values determined by sulphite oxidation (SOTES) were consistently higher than those established during re-aeration (SOTER) suggesting that the chemical reaction was enhancing the mass transfer. The chemical reaction was sufficiently fast in the case of the GP membrane, that the gas phase limited the mass transfer. The GP membrane operating at 1.2 atm had a SOTES of 70.6% and a SOTER of 52.2%. SOTER for the coarse bubble and fine bubble diffusers were 3.8% and 23.6%, respectively. This is comparable to the manufacturer's values, corrected for depth of 3.4% and 18.3%, respectively. Particularly, the derived OTE values were used to evaluate differences in energy consumption for a conventional treatment plant achieving carbon removal and nitrification. This analysis highlights the potential energy efficiency of GP membranes, which could be considered for the design of the membrane modules.

scholarly journals The Changing and Distribution Laws of Oxygen Transfer Efficiency in the Full-Scale IFAS Process

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1933
Author(s):  
Xuyang Liu ◽  
Xuejun Bi ◽  
Qing Huang ◽  
Xiaodong Wang ◽  
Ruihuan Gu ◽  
...  
Keyword(s):  
Oxygen Transfer ◽  
Wastewater Treatment Plants ◽  
Plug Flow ◽  
Full Scale ◽  
Transfer Efficiency ◽  
Factors Affecting ◽  
Fine Bubble ◽  
Oxygen Transfer Efficiency ◽  
Distribution Laws ◽  
Two Sides

The integrated fixed-film activated sludge (IFAS) process has been widely used in the upgrading of wastewater treatment plants (WWTPs). The oxygen transfer efficiency (αOTE) is of great significance to the design and operation of the IFAS process. The carrier filling ratio (CFR) and aeration type are two critical factors affecting αOTE and standard oxygen transfer efficiency (αSOTE). However, the distribution and changing laws of αOTE and αSOTE in the full-scale IFAS process areunclear. To optimize the operation of a WWTP and to improve the αOTE of the aeration systems, several off-gas tests were conducted under different aeration types and different CFRs. The results show that for the aerobic tank investigated (the ratio of length and width was 8:1), the αOTE and the αSOTE of the middle of the aeration systems were higher than those of the other two sides. However, the reason for the low αOTE at the beginning and the end of the tank may be different. Coarse-bubble aeration systems had a lower αOTE and almost the same oxygenation capacity (αSOTE) as the fine-bubble aeration systems under constant CFR (43%). The average αSOTE (18.7–28.9%) of the hybrid aeration systems increased with increasing CFR (7.7–57.7%), and different locations exhibited different degrees of change. The results reveal the distribution and changing law of the αOTE of aeration systems in the IFAS process, and attention should be paid to the improvement of the OTE of the plug-flow IFAS process.

Oxygen Transfer Measurements and Air Distribution for an Aeration Basin with Fine Bubble Diffusers

1988 ◽  
Vol 20 (4-5) ◽  
pp. 77-84
Author(s):  
Read Warriner
Keyword(s):  
Dissolved Oxygen ◽  
Uniform Distribution ◽  
Oxygen Transfer ◽  
Transfer Efficiency ◽  
Air Distribution ◽  
Dissolved Oxygen Concentration ◽  
Air Supply ◽  
Fine Bubble ◽  
Oxygen Transfer Efficiency ◽  
Longitudinal Pattern

The off-gas method was used to study oxygen transfer efficiency in a long, narrow activated sludge basin. The basin was equipped with square, ceramic, fine pore diffuser plates arranged in a uniform longitudinal pattern at a depth of 4.3 m. Oxygen transfer efficiency, at 20°C and zero dissolved oxygen concentration, during the second and third years following diffuser cleaning, was between 15 and 17%. A uniform distribution of air to the tank was compared with a tapered air supply (more air at the inlet end and less at the outlet). The tapered air supply gave lower dissolved oxygen at the outlet and did not increase overall oxygen transfer. With a 3 to 5-fold variation in air flow, at either the inlet or outlet zone of the basin, the oxygen transfer efficiency, adjusted for zero dissolved oxygen, stayed constant.

The Effect of Nozzle Type on Air Entrainment by Plunging Water Jets

2002 ◽  
Vol 37 (3) ◽  
pp. 599-612 ◽  
Author(s):  
Tamer Bagatur ◽  
Ahmet Baylar ◽  
Nusret Sekerdag
Keyword(s):  
Penetration Depth ◽  
Oxygen Transfer ◽  
Free Water ◽  
Air Entrainment ◽  
Water Jet ◽  
Transfer Efficiency ◽  
Entrainment Rate ◽  
Water Jets ◽  
Air Entrainment Rate ◽  
Oxygen Transfer Efficiency

Abstract In this study, for the plunging water jet aeration system using various inclined nozzle types, bubble penetration depth, air entrainment rate, water jet expansion, effect of water jet circumference at impact point, oxygen transfer coefficient and oxygen transfer efficiency which changed depending on the water jet velocity, were researched in an air-water system. Numerous studies were conducted with circular nozzles. The present study describes new experiments performed with different nozzle types. Three types of nozzles were examined, i.e., those with circular, ellipse and rectangle duct with rounded ends. Experimental results showed that water jets produced with ellipse and rectangle duct with rounded ends nozzles have very different flow characteristics, entrainment patterns on free water jet surface, and submerged water jet region within the receiving tank. Higher air entrainment rate and oxygen transfer efficiency was observed in the rectangle duct with rounded ends nozzle due to water jet expansion. Bubble penetration depth, however, is lower for the rectangle duct with rounded ends nozzle than for the other nozzles. The ellipse nozzle provided the highest bubble penetration depth. These results showed that it is appropriate to use ellipse nozzle in aeration of deep pool and rectangle duct with rounded ends nozzle in the applications where high bubble concentration is desirable.

Oxygen Transfer Efficiency Measurements Using Off-Gas Techniques

1989 ◽  
Vol 21 (10-11) ◽  
pp. 1295-1300 ◽  
Author(s):  
W. C. Boyle ◽  
B. G. Hellstrom ◽  
L. Ewing
Keyword(s):  
Oxygen Uptake ◽  
Uptake Rate ◽  
Oxygen Transfer ◽  
Oxygen Uptake Rate ◽  
Transfer Efficiency ◽  
Theoretical Development ◽  
Process Conditions ◽  
Uptake Rates ◽  
Oxygen Transfer Efficiency ◽  
On Line

The off-gas technique for measuring oxygen transfer efficiency in aeration tanks under process conditions was proposed as an accurate technique for calibrating or verifying on-line methods used to estimate oxygen uptake rates. The theoretical development of the off-gas technique was presented. Application of this technique in verifying or calibrating existing on-line methods for estimating oxygen uptake rate was presented. Direct application as an on-line method for estimating oxygen uptake rate was also discussed.

Experience with Ceramic Plate Diffusers in Large Activated Sludge Plants

1992 ◽  
Vol 25 (4-5) ◽  
pp. 127-134
Author(s):  
R. Warriner ◽  
T. C. Rooney
Keyword(s):  
Activated Sludge ◽  
Oxygen Transfer ◽  
Cost Effective ◽  
Transfer Efficiency ◽  
Ceramic Plate ◽  
Flat Plates ◽  
Higher Power ◽  
Oxygen Transfer Efficiency ◽  
Basin Floor ◽  
The Difference

Fine pore aeration systems were evaluated in a U.S.EPA sponsored study of oxygen transfer efficiency in 26 activated sludge plants. Two plants in the study, those of the Milwaukee Metropolitan Sewerage District, had aeration systems composed of flat plates grouted into containers placed flush with the basin floor. The remaining plants in the study had aeration systems utilizing various disk, dome, and tube devices that are now in far more widespread use than the flat plates. The District's aeration basins gave better oxygen transfer efficiency than the other ceramic diffuser systems studied. The difference may have been the result of the high tank area to diffuser area ratio and the low air flux rates associated with the plate systems. At one MMSD plant there were also four basins with recently installed ceramic disk diffuser systems. This provided an opportunity for side-by-side comparisons between the disks and the flat plates in containers. An analysis of diffuser system first costs and energy costs indicated that the ceramic plate system could be cost effective at higher power costs, but not at the prices presently paid by the District for power.

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