Mathematical modeling of aeration efficiency and dissolved oxygen provided by stepped cascade aeration

2011 ◽  
Vol 63 (1) ◽  
pp. 1-9 ◽  
Author(s):  
A. Khalifa ◽  
S. Bayoumi ◽  
O. El Monayeri
Keyword(s):  
Mathematical Modeling ◽  
Dissolved Oxygen ◽  
Computer Program ◽  
Environmental Engineering ◽  
Pollutant Load ◽  
Aeration Efficiency ◽  
Cascade Structure ◽  
Stepped Cascade ◽  
Different Levels

Mathematical modeling has been a vital tool in the field of environmental engineering. Various models have been developed to simulate the level of aeration efficiency (AE) provided by different aerating structures to raise levels of dissolved oxygen (DO) in streams; one of which is the stepped cascade structure. Three models developed by Gameson et al. WRL, and Nakasone, in addition to Qual2k, a computer program for stream modeling, have been used in this research; values of AEs obtained have been compared to those computed using DO measured from a built model at a WWTP. A stepped cascade structure was installed with different heights to aerate five flowrates with different levels of COD. An adjustment has been made to the Nakasone model to test the effect of pollutant load on the amount of aeration that could be reached. Values of AEs computed using the Gameson model were 30%, 39.5%, and 40% for cascade heights (Hd) 45, 60, and 75 cm respectively for the five flowrates (q) that ranged from 21–66 m3/hr. Values of AEs from WRL model were 32.8%, 42%, and 43% consequently. Values of AEs from Nakasone model ranged from 4.6–7.5%, 6–10%, and 7.6–12% respectively. For the adjusted Nakasone model, values of AEs ranged from 3.2–4.9%, 3.3–5.3%, and 4.1–6.7% respectively. Finally, the AEs computed using the values of downstream DO generated by Qual2k ranged from 4–18%, 2–15%, and 2.5–5.1% correspondingly. Around 80% of the downstream DO values computed using the Nakasone and adjusted Nakasone model were closer to those measured in the field, thus more reliable in cascade design.

A Survey for Salinity Intrusion and Pollution Assessment in Maputo Estuary

1987 ◽  
Vol 19 (5-6) ◽  
pp. 823-832 ◽  
Author(s):  
J. M. Salomão
Keyword(s):  
Dissolved Oxygen ◽  
Industrial Wastewater ◽  
Pollution Assessment ◽  
Saturation Level ◽  
Salinity Intrusion ◽  
Pollutant Load ◽  
Oxygen Levels ◽  
Salinity Gradients

Following surveys recently carried out in Maputo estuary, a survey with the purpose of acquiring data required to characterize the estuary was carried out in December 1983. After reviewing the hydrology of the tributaries to the estuary, the parameters to be monitored - salinity, conductivity, temperature, and dissolved oxygen, are referred. Finally, taking also into account previous information available, an evaluation of the results, and an assessment of the estuary are done. The estuary can be classified as well mixed, since the vertical salinity gradients found are small. The Umbeluzi estuary, however, is partially mixed. Temperature decreases with the depth, and when moving downstream. Some pollution was found along the lower part of the estuary, probably due to the discharge of domestic and industrial wastewater, which brings the dissolved oxygen figures below the saturation level. As for the upper part of the estuary, the dissolved oxygen levels are not only dependent on the pollutant load, but also on the growing of algae, which by photosynthesis under daylight produce oxygen that dissolves into the water. Quite often, the dissolved oxygen figures are above the saturation level. The growth of algae could be due to the input of phosphorus and nitrogen brought in by the tributary streams. A pollutant load discharged upstream could be the reason for some pollution seen in the Umbeluzi estuary.

Aeration characteristics of a rectangular stepped cascade system

2010 ◽  
Vol 61 (2) ◽  
pp. 415-420 ◽  
Author(s):  
Sanjib Moulick ◽  
Naresh V. Tambada ◽  
Basant K. Singh ◽  
B. C. Mal
Keyword(s):  
Surface Area ◽  
Loading Rate ◽  
Experimental Results ◽  
Step Height ◽  
Optimum Number ◽  
Hydraulic Loading Rate ◽  
Hydraulic Loading ◽  
Aeration Efficiency ◽  
Stepped Cascade ◽  
Independent Parameters

Aeration experiments, maintaining nappe flow conditions, were carried out on a rectangular stepped cascade of total height 3.0 m to determine the total number of steps, slope of the entire cascade and hydraulic loading rate at which maximum overall aeration efficiency occurs, keeping the surface area of individual steps constant. Based on dimensional analysis, the overall aeration efficiency at standard conditions (E20) was expressed as a function of square of total number of steps (N2) and dimensionless discharge (dc/h), where dc and h represent critical depth in a rectangular prismatic channel and individual step height respectively. An empirical equation with E20 as the response and N2 and dc/h as the independent parameters was developed based on the experimental results subject to 36 ≤ N2 ≤ 196 and 0.009 ≤ dc/h ≤ 0.144. The experimental results showed that the overall aeration efficiency (E20) for a particular step height of stepped cascade increases with increase in dc/h up to a certain value and then decreases. This may be due to at higher dc/h, i.e., at higher hydraulic loading rate, the flow approaches the transition zone and thereby aeration efficiency decreases. E20 was also found to increase with number of steps at any hydraulic loading rate, because of the increased surface area of fall. The optimum number of steps, slope of the entire stepped cascade and hydraulic loading rate were found to be 14, 0.351 and 0.009 m2/s respectively producing the maximum value of overall aeration efficiency of 0.90.

A Mathematical Approach to Designing Insulators

2020 ◽  
pp. 244-257
Author(s):  
Kathryn Electa Pedings-Behling
Keyword(s):  
Mathematical Modeling ◽  
High School ◽  
Rate Of Change ◽  
Hot Water ◽  
Mathematical Approach ◽  
Aesthetic Value ◽  
Advanced Students ◽  
Extension Activity ◽  
The Aesthetic ◽  
Different Levels

How do we keep hot drinks hot and cold drinks cold? Companies such as Tervis, YETI, and Thermos spend their time researching and designing products around that very question. In this lesson, students will discover, through mathematical modeling, which materials provide the best insulation and be tasked with designing their own insulator. This lesson has been designed at two different levels for students from grade three through high school with an optional extension activity for more advanced students. Students will use technology to explore the rate of change of the temperature of hot water over two minutes using different insulation materials. After this exploration, students will use the data they have collected to determine the best materials for designing their own insulator. This insulator will then be judged based on the ability to keep a hot drink hot and on the aesthetic value.

Aeration Performance of Triangular Notch Weirs at Recirculating System

2001 ◽  
Vol 36 (1) ◽  
pp. 121-132 ◽  
Author(s):  
Ahmet Baylar ◽  
Tamer Bagatur ◽  
Ahmet Tuna
Keyword(s):  
Dissolved Oxygen ◽  
Aquatic Organisms ◽  
The Other ◽  
Hydraulic Structures ◽  
Air Bubbles ◽  
Adequate Supply ◽  
Oxygen Levels ◽  
Aeration Efficiency ◽  
Aeration Performance ◽  
Better Than

Abstract An adequate supply of dissolved oxygen is essential for the survival of aquatic organisms. Hydraulic structures can increase dissolved oxygen levels by creating turbulent conditions, where small air bubbles are carried into the bulk of the flow. Plunging overfall jets from weirs at recirculating systems are a particular instance of this. This paper seeks triangular notch weirs having different weir angle (α) and how they affect the aeration performance. It is demonstrated that the aeration efficiency of a 90° triangular notch weir is generally better than that of the other weirs.

A Mathematical Approach to Designing Insulators

2017 ◽  
pp. 247-259
Author(s):  
Kathryn E. Pedings-Behling
Keyword(s):  
Mathematical Modeling ◽  
High School ◽  
Rate Of Change ◽  
Hot Water ◽  
Mathematical Approach ◽  
Aesthetic Value ◽  
Advanced Students ◽  
Extension Activity ◽  
The Aesthetic ◽  
Different Levels

How do we keep hot drinks hot and cold drinks cold? Companies such as Tervis, YETI, and Thermos spend their time researching and designing products around that very question. In this lesson, students will discover, through mathematical modeling, which materials provide the best insulation and be tasked with designing their own insulator. This lesson has been designed at two different levels for students from grade three through high school with an optional extension activity for more advanced students. Students will use technology to explore the rate of change of the temperature of hot water over two minutes using different insulation materials. After this exploration, students will use the data they have collected to determine the best materials for designing their own insulator. This insulator will then be judged based on the ability to keep a hot drink hot and on the aesthetic value.

scholarly journals Mathematical model for power consumption at mixing of industrial and domestic wastewater sludge

2013 ◽  
Vol 24 (2) ◽  
pp. 115-120
Author(s):  
Ancaelena Eliza Sterpu ◽  
Claudia Irina Koncsag ◽  
Anca Iuliana Dumitru ◽  
Alina-Daniela Mihalcea
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Power Consumption ◽  
Domestic Wastewater ◽  
Wastewater Sludge ◽  
Linear Functions ◽  
Speed Ratio ◽  
Function Type ◽  
Variation Versus ◽  
Different Levels

AbstractPhysical investigations have been carried out to characterize the power consumption in a laboratory autoclave vessel equipped with an anchor impeller (diameter d = 0.068 mm), without baffles, at 8 speed ratio, from 100 to 800 rpm. The laminar flow regime was investigated using sludge proceeding from the treatment of mixed industrial and domestic wastewater, with a view to its subsequent processing: mixing, filtration, dewatering. The mathematical modeling focused on finding an accurate equation linking the Power number (Np) and the Reynolds number (Re) at different levels (H) of sludge in the vessel. The rheological curves indicate that the sludge have non-Newtonian behaviors which are better described by the Herschel-Buckley model. The models resulted from the Np variation versus Re are power function type Np = a ×Reb , where the coefficient a is a linear functions of H/d ratio and b = -1.016 have a constant value.

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