Bubble generation by micro-orifices with application on activated sludge wastewater treatment

Mohseni, Ehsan; Herrmann-Heber, Robert; Reinecke, Sebastian Felix; Hampel, Uwe

doi:10.1016/j.cep.2019.04.011

Cited by 20 publications

(12 citation statements)

References 38 publications

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“…As of today, flexible membranes are widely used for aeration in municipal wastewater treatment plants as disc, plate or plate diffusers. The generated bubble sizes with such industrial-used diffusers are in the range of 2 mm-5 mm [8][9][10][11]. These findings found larger bubble sizes for commercial membrane diffusers than the optimal bubble size suggested by Motarjemi and Jameson [3].…”

Section: Introductionmentioning

confidence: 66%

“…The enhanced oxygen transfer through bubbles of 1 mm or less would optimize the energy efficiency in wastewater treatment further with less blower power needed for aeration processes and simultaneously provide sufficient oxygen for degradation processes. Mohseni et al investigated the generation of fine bubbles from micro-orifices and analyzed the Sauter mean diameter, d 32 , of the generated bubbles together with the oxygen transfer rate [8]. Using orifices with a diameter smaller than 225 µm, they obtained bubbles with d 32 ≤ 2 mm and an enhancement in the oxygen transfer of up to 22% compared to industrial rubber membrane diffusers.…”

Section: Introductionmentioning

confidence: 99%

“…The motivation for using micro-orifices stems from our previous investigations on the bubble formation from such orifices [8,15]. Therefore, in this study, micro-perforated diffusers with orifice diameters in the range of 0.03 mm-0.07 mm with two different bubble distribution arrangements are investigated to assess their performance in terms of oxygen transfer in a pilot-scale test facility.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Oxygen Mass Transfer Study of Micro-Perforated Diffusers

et al. 2021

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We studied new micro-perforated diffuser concepts for the aeration process in wastewater treatment plants and evaluated their aeration efficiency. These are micro-perforated plate diffusers with orifice diameters of 30 µm, 50 µm and 70 µm and a micro-perforated tube diffuser with an orifice diameter of 50 µm. The oxygen transfer of the diffuser concepts is tested in clean water, and it is compared with commercial aerators from the literature. The micro-perforated tube diffuser and micro-perforated plate diffusers outperform the commercial membrane diffusers by up to 44% and 20%, respectively, with regard to the oxygen transfer efficiency. The most relevant reason for the improved oxygen transfer is the fine bubble aeration with bubble sizes as small as 1.8 mm. Furthermore, the more homogenous cross-sectional bubble distribution of the micro-perforated tube diffuser has a beneficial effect on the gas mass transfer due to less bubble coalescence. However, the pressure drop of micro-perforated diffusers seems to be the limiting factor for their standard aeration efficiencies due to the size and the number of orifices. Nevertheless, this study shows the potential for better aeration efficiency through the studied conceptual micro-perforated diffusers.

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Section: Introductionmentioning

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimental Oxygen Mass Transfer Study of Micro-Perforated Diffusers

et al. 2021

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“…Bubbles are ubiquitous in nature and play an essential role in increasing oxygen in water, [1,2] sewage treatment, [3,4] ocean heat transfer, [5,6] and so on. However, the leakage of large amounts of methane gas in the ocean is both an energy loss and an aggravation of the global warming trend.…”

Section: Introductionmentioning

confidence: 99%

Laser Microfabrication of Janus Tapered Aluminum Foil for Self‐Driven Transportation of Bubbles

et al. 2022

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“…Aeration is the most energy consuming process in WWTPs, and consumes 50% to 90% of electricity usage [12]. It is not surprising then that a significant number of studies have been conducted to investigate ways to increase performance of aeration devices [13][14][15]. Since compressors or blowers require external power to run, a different approach is envisioned in this study by adding a secondary compressor (also called "bleed air") to the power cycle so as to eliminate the associated generator inefficiency in the turbine as well as to directly use the shaft power in the Brayton cycle, thereby avoiding motor inefficiency.…”

Section: Introductionmentioning

confidence: 99%

Can a Wastewater Treatment Plant Power Itself? Results from a Novel Biokinetic-Thermodynamic Analysis

Erguvan

MacPhee

2021

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The water–energy nexus (WEN) has become increasingly important due to differences in supply and demand of both commodities. At the center of the WEN is wastewater treatment plants (WWTP), which can consume a significant portion of total electricity usage in many developed countries. In this study, a novel multigeneration energy system has been developed to provide an energetically self-sufficient WWTP. This system consists of four major subsystems: an activated sludge process, an anerobic digester, a gas power (Brayton) cycle, and a steam power (Rankine) cycle. Furthermore, a novel secondary compressor has been attached to the Brayton cycle to power aeration in the activated sludge system in order to increase the efficiency of the overall system. The energy and exergy efficiencies have been investigated by varying several parameters in both WWTP and power cycles. The effect of these parameters (biological oxygen demand, dissolved oxygen level, turbine inlet temperature, compression ratio and preheater temperature) on the self-efficiency has also been investigated. It was found here that up to 109% of the wastewater treatment energy demand can be produced using the proposed system. The turbine inlet temperature of the Brayton cycle has the largest effect on self-sufficiency of the system. Energy and exergy efficiencies of the overall system varied from 35.7% to 46.0% and from 30.6% to 33.55%, respectively.

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Bubble generation by micro-orifices with application on activated sludge wastewater treatment

Cited by 20 publications

References 38 publications

Experimental Oxygen Mass Transfer Study of Micro-Perforated Diffusers

Experimental Oxygen Mass Transfer Study of Micro-Perforated Diffusers

Laser Microfabrication of Janus Tapered Aluminum Foil for Self‐Driven Transportation of Bubbles

Can a Wastewater Treatment Plant Power Itself? Results from a Novel Biokinetic-Thermodynamic Analysis

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