scholarly journals Improving aeration systems in saline water (part II): effect of different salts and diffuser type on oxygen transfer of fine-bubble aeration systems

2021 ◽  
Author(s):  
J. Behnisch ◽  
M. Schwarz ◽  
J. Trippel ◽  
M. Engelhart ◽  
M. Wagner
Keyword(s):  
Oxygen Transfer ◽  
Large Scale ◽  
Saline Water ◽  
Tap Water ◽  
Pilot Scale ◽  
Mixed Salt ◽  
Water Oxygen ◽  
Aeration System ◽  
Fine Bubble ◽  
Scale Test

Abstract The objective of the present study is to investigate the different effects on the oxygen transfer of fine-bubble aeration systems in saline water. Compared to tap water, oxygen transfer increases due to the inhibition of bubble coalescence. In Part I of the present study, we investigated in lab-scale experiments the effect of design of diffuser membrane. The objective of Part II is the assessment of effects of different salts, diffuser type and diffuser density. We measured the concentration of various salts (MgCl2; CaCl2; Na2SO4; NaCl; KCl) above which coalescence is fully inhibited and oxygen transfer reaches its maximum (referred to as the critical coalescence concentration; CCC). For this purpose, we developed a new analytical approach, which enables to investigate the coalescence behaviour of any aeration system and (mixed) salt solution quickly and easily by evaluating the results of oxygen transfer tests. To investigate the transferability to large scale and the effect of diffuser type and density, we repeated lab-scale experiments in a 17,100 L pilot scale test tank and carried out additional tests with tube and plate diffusers at different diffuser densities. The results show, that despite the higher pressure drop, diffusers with dense slit density and smaller slits are to be recommended in order to improve efficiency of aeration systems in saline water.

scholarly journals Developing bacterial set box media containing fiqh al biah for Islamic senior high school

2021 ◽  
Vol 7 (1) ◽  
pp. 83-94
Author(s):  
Uswatul Wadhichatis Saniyyah ◽  
Nur Hayati ◽  
Saifullah Hidayat
Keyword(s):  
Public School ◽  
Large Scale ◽  
Pilot Scale ◽  
Three Dimensions ◽  
Biology Teacher ◽  
The Third ◽  
Bacterial Classification ◽  
The Media ◽  
Scale Test ◽  
Islamic Values

The limitations of bacterial visualization media make bacteria consider as abstract and difficult material to study. Furthermore, the implementation of bacteria material and the integration of Islamic values are difficult to teach. This research aimed at developing and validating the BSB (Bacterial Set Box) media containing fiqh al biah. The method used in this research was R&D (Research and Development) with 4D model (Define, Design, Develop, and Disseminate) by Thiagarajan et al. The media developed was three dimensions (3D), which was packed up in a box which contained three packages. The first box was bacterial visualization; the second box was bacterial classification; the third box was 3D box containing fiqh al biah. The field test was carried out in Al Azhar Islamic Public School 16 and MA Nurussalam Semarang. The results showed that the validation percentages were 94% (material expert), 79% (media expert), 96% (integration expert), 92% (biology teacher of Al Azhar Islamic Public School 16), and 86% (biology teacher of MA Nurussalam). A pilot scale test and a large-scale test showed very feasible. It can be concluded that BSB media containing fiqh al biah is very feasible to use.

Applying fine bubble aeration to small aeration tanks

2001 ◽  
Vol 44 (2-3) ◽  
pp. 203-210 ◽  
Author(s):  
Ph. Duchène; ◽  
E. Cotteux ◽  
S. Capela
Keyword(s):  
Oxygen Transfer ◽  
Wastewater Treatment Plants ◽  
Open Channels ◽  
Aeration System ◽  
Fine Bubble ◽  
Aeration Efficiency ◽  
Practical Guidelines ◽  
High Investment ◽  
Cylindrical Tanks ◽  
Grid Layout

Because the aeration system in an activated sludge plant typically represents a large part of the total energy requirements, designers and operators need accurate oxygen transfer information to make the aeration system as energy efficient as possible. This paper presents clean water tests performed at 38 wastewater treatment plants. The Specific Aeration Efficiency results (SAE, kgO2/kWh) are reported for: (1) large open channels (volume higher than 1000 m3), (2) small open channels, (3) total floor coverage cylindrical tanks, and (4) cylindrical tanks with a grid arrangement. Some practical guidelines can be drawn, some of them being: (1) high SAE can be achieved at small aeration tanks (<1000m3), applying cylindrical tanks with a total floor coverage arrangement of diffusers, volumetric blowers, and moderate air flow rates per diffuser area; (2) the high investment cost of this configuration can be justified with respect to a grid layout characterized by spiral liquid circulation which affects the oxygen transfer; (3) small open channels can meet sufficient SAE values but fail to meet in this range of tank volumes those of total floor coverage cylindrical tanks.

scholarly journals Oxygen transfer into activated sludge with high MLSS concentrations

2003 ◽  
Vol 47 (11) ◽  
pp. 297-303 ◽  
Author(s):  
J. Krampe ◽  
K. Krauth
Keyword(s):  
Activated Sludge ◽  
Economic Efficiency ◽  
Efficient Method ◽  
Oxygen Transfer ◽  
Membrane Bioreactor ◽  
High Solids ◽  
Aeration System ◽  
Fine Bubble ◽  
Sludge Properties ◽  
The Impact

In this report, tests on the impact of the sludge properties on the oxygen transfer at low and high solids contents are presented. Additional to the oxygen transfer tests, the activated sludge was intensively analysed to examine the changes of the α-factor in relation to the sludge properties (rheology, EPS, CST, etc.). The a-factor did strongly decrease in all sludge types at increasing MLSS or increasing viscosity, respectively. In the second test stage, the impact of the aeration system was examined in detail. For these tests, the same sludge from a membrane bioreactor was used throughout. Apart from the impact of the power density in the reactor and the specific air throughput, the main focus was on the economic efficiency of the examined systems in cases of high MLSS. It became apparent that up to solids contents of 18 g/l the fine-bubble aeration is the most economically efficient method.

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.

Age Advantages of Emotional Experience during the COVID-19 Pandemic are Robust, but Diminished Compared to Pre-pandemic Conditions

2020 ◽  
Author(s):  
Rui Sun ◽  
Disa Sauter
Keyword(s):  
Older Adults ◽  
Large Scale ◽  
Negative Emotion ◽  
Emotional Experience ◽  
Negative Emotions ◽  
Older Individuals ◽  
Selection Strategies ◽  
Scale Test ◽  
Prolonged Stress

Getting old is generally seen as unappealing, yet aging confers considerable advantages in several psychological domains (North & Fiske, 2015). In particular, older adults are better off emotionally than younger adults, with aging associated with the so-called “age advantages,” that is, more positive and less negative emotional experiences (Carstensen et al., 2011). Although the age advantages are well established, it is less clear whether they occur under conditions of prolonged stress. In a recent study, Carstensen et al (2020) demonstrated that the age advantages persist during the COVID-19 pandemic, suggesting that older adults are able to utilise cognitive and behavioural strategies to ameliorate even sustained stress. Here, we build on Carstensen and colleagues’ work with two studies. In Study 1, we provide a large-scale test of the robustness of Carstensen and colleagues’ finding that older individuals experience more positive and less negative emotions during the COVID-19 pandemic. We measured positive and negative emotions along with age information in 23,629 participants in 63 countries in April-May 2020. In Study 2, we provide a comparison of the age advantages using representative samples collected before and during the COVID-19 pandemic. We demonstrate that older people experience less negative emotion than younger people during the prolonged stress of the COVID-19 pandemic. However, the advantage of older adults was diminished during the pandemic, pointing to a likely role of older adults use of situation selection strategies (Charles, 2010).

Energy savings potential of new aeration system: Full scale trials

2012 ◽  
Vol 7 (4) ◽  
Author(s):  
A. Lazić ◽  
V. Larsson ◽  
Å. Nordenborg
Keyword(s):  
Control System ◽  
Energy Consumption ◽  
Total Energy ◽  
Energy Savings ◽  
Treatment Plant ◽  
Full Scale ◽  
Total Energy Consumption ◽  
Aeration System ◽  
Fine Bubble ◽  
Aeration Control

The objective of this work is to decrease energy consumption of the aeration system at a mid-size conventional wastewater treatment plant in the south of Sweden where aeration consumes 44% of the total energy consumption of the plant. By designing an energy optimised aeration system (with aeration grids, blowers, controlling valves) and then operating it with a new aeration control system (dissolved oxygen cascade control and most open valve logic) one can save energy. The concept has been tested in full scale by comparing two treatment lines: a reference line (consisting of old fine bubble tube diffusers, old lobe blowers, simple DO control) with a test line (consisting of new Sanitaire Silver Series Low Pressure fine bubble diffusers, a new screw blower and the Flygt aeration control system). Energy savings with the new aeration system measured as Aeration Efficiency was 65%. Furthermore, 13% of the total energy consumption of the whole plant, or 21 000 €/year, could be saved when the tested line was operated with the new aeration system.

Use of Low Pressure Mercury Lamps for the Photodecomposition of Iron Cyanide in Gold Mill Effluents

1985 ◽  
Vol 20 (2) ◽  
pp. 111-119 ◽  
Author(s):  
J.H. Carey ◽  
S.A. Zaidi
Keyword(s):  
Ultraviolet Light ◽  
High Intensity ◽  
Experimental Evaluation ◽  
Low Pressure ◽  
Pilot Scale ◽  
Weak Acid ◽  
Potassium Ferricyanide ◽  
Technical Feasibility ◽  
Iron Cyanide ◽  
Scale Test

Abstract The use of ultraviolet light (UV) from low pressure mercury lamps for destroying iron cyanide in synthetic and actual gold mill effluents was evaluated in this study. For the light intensities used in this study, UV irradiation was not able to efficiently destroy cyanide. However, it converted iron cyanide to a weak acid dissociable form which was destroyed by chlorine. Data from several bench-scale tests and one pilot scale test were used to estimate quantum efficiencies (moles iron cyanide destroyed/einstein). These efficiencies ranged from 0.2% to 1%; approximately 30% to 90% lower than those reported in the literature for potassium ferricyanide. The data collected during the study demonstrated the technical feasibility of using UV in conjunction with chlorination for destroying iron cyanide in gold mill effluents. However, low pressure mercury lamps do not appear to be a practical UV source for this purpose. Irradiation with high intensity lamps may be more practical and is recommended for experimental evaluation.

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