Design Characteristics of Venturi Aeration System

New Delhi Publishers, 2017

Venturi system helps to air drawn into a flowing stream of water transferring the oxygen from air to water till they reach the water surface and burst due to Bernoulli's principle in form of bubbles. The efficacy of venturi as an aeration device is primarily dependent on the geometry and the flow conditions prevailing inside. Presently, the diameter and placement of holes in a venturi under different flow conditions was studied to determine the performance of the venturi as an aerator. To evaluate the results, SOTR and SAE were calculated and compared for analyse their performance. The study involved selecting 5 different throat lengths each having multiple hole of 1 mm diameter. The hole distance from the start of the throat section, which has been characterised as the effective distance (ED) has been so selected that all the ED's are different. The ED's selected for study varied from 2 mm to 46 mm under three different discharges of 1.72 m 3 /h, 2.02 m 3 /h and 2.38 m 3 /h. Firstly, it was observed from the experiments that the venturi performs best when the ED is less. Secondly, it was also observed that both SOTR and SAE are more for higher discharge. Next, it was also found that increasing the throat length beyond a certain value has a negative effect on the SOTR and SAE. It was also observed that among all the possible combinations the best was for the 10 mm throat section with the hole situated just adjacent to the start of the throat section and performing at a high discharge. Highlights m Venturi aeration is a novel scheme of air water mixing at throat section. Other than the position of throat hole was foundthat the chief factor influencing the air entrainment rate and the oxygen transfer efficiency.

Aquaculture studies, 2022

Venturi aeration is an economical method to increase dissolved oxygen (DO) in aquatic water bodies. For this paper, aeration experiments were conducted with 200 litres volume of the water tank, having dimensions of 90 cm length, 55 cm breadth, and 45 cm depth. The venturi was fabricated keeping the dimension of converging and diverging length same, i.e., 76 mm and throat length of 100 mm. The venturi aeration system was operated with six different discharge rates (0.00025, 0.00033, 0.00042, 0.00050, 0.00058 and 0.00067 m3/s). This work is intended to estimate the effect of varying discharges on the efficiency of venturi aerator in terms of standard oxygen transfer rate (SOTR) and standard aeration efficiency (SAE). The experiment shows promising results in terms of SOTR and SAE at moderate to high discharge rates, on the other hand a declining trend is seen when the liquid discharge rate is too high. The oxygen transfer rate was found to have a good relationship with the discharge rate. How to cite

Journal of Al-Azhar University Engineering Sector, 2021

Sufficient dissolved oxygen is required for helpful water quality. Natural stream cleansing procedures need enough oxygen levels for the purpose of supply for aerobic life systems. The happening of oxygen and water mixing together is titled aeration. There are several techniques to add air or oxygen to water, for instance open air reservoirs, submergible pumps, domestic aeration systems, compressor systems and air pump systems. However, the Venturi system, relied on the easiness of Ejectors, gives a easy, preservation free aeration solution. venturi system permits air to be injected inside running water from air inlet orifices and so rises oxygen levels in the water. The main objective of this research is to evaluate effect of geometric characteristics on the aeration efficiency in the venturi system. To achieve this goal, the venturi is designed and carried out, from transparent polycarbonate. Experiments were conducted under clear-water conditions at different discharges (Qwater)...

Water Science & Technology, 2009

Six aerator modules constructed using venturi air injectors connected in either series or parallel were evaluated and compared for their oxygen transfer coefficients (OTC), standard oxygen transfer rate (SOTR), and standard oxygenation efficiency (SOE) determined by clean water tests. Modules in series (module a, b, c) included one, two, and three venturi injectors, respectively. The aerator module with two (module d) and three (module e, f) venturi injectors in parallel were used, while module f had less friction and more even flow rate in each line compared with module e. The results showed that the OTC, SOTR, and SOE for the six different module configurations (module a, b, c, d, e, f) were 4. 54, 3.79, 3.58, 8.37, 5.93 and 11.87 h 21 ; 0.10, 0.09, 0.09, 0.18, 0.15, and 0.31 kgO 2 /h; and 0.07, 0.06, 0.06, 0.12, 0.10, and 0.21 kgO 2 /kWh, respectively. The observations indicate that a 3-fold increase in SOTR and 3.5-fold increase in SOE can be obtained by simply changing the way that venturi air injectors are connected, which suggests that it is possible to improve the aeration efficiency of a venturi type aeration system by innovative aerator module designs. In view of the situation that the venturi aeration systems currently used for swine manure lagoons need significant improvement in their performance in order to match the cost-effective requirement, more research in aerator module development is needed so that effective control of odor from liquid swine manure lagoons can be achieved at an affordable cost. The technology such developed can also be applied to other livestock species.

Euro-Mediterranean Journal for Environmental Integration

The immense environmental challenges facing the world today and in the years to come can be met only through mobilizing the best engineers and scientists in the environmental sector and using innovative and cost-effective solutions. Hydraulic structures can significantly improve dissolved oxygen levels by creating turbulent conditions in which small air bubbles are caused in most of the flow. Therefore, a venturi device can be used as highly effective aerator in aeration processes. However, the hydraulic equipment can be exposed to anomalies due to pressure variations. This is generally caused by the air phase development. Moreover, it considerably induces wall materials, erosion and corrosion. In this work, particular attention was paid to the pressure change in closed venturi pipes because its decrease generates air bubbles and its increase implies their implosion. Both mathematical and experimental tools were used to describe the pressure evolution with flow rates and air bubbles size. Experimental tests were carried out using a transparent rectangular venturi. Pressure field and air section length were measured for different coming flow rates of water. On the other hand, the Rayleigh Plesset ordinary differential equation was used to explain this phenomenon under spherical bubbles hypothesis. High values of the Reynolds dimensionless numbers, at both the upstream and throat sections, indicate a fully turbulent flow through the venturi. Inception was visualized when the air phase starts, before the pressure attains the vapour value. The mathematical model solution shows three flow zones for the pressure field evolution with the relationship between air bubble radius and liquid phase size. So, an unstable flow, inception and a stable cavitating flow were highlighted. Also, the experimental results allow distinguishing these zones depending on the flow rate values. The flow parameters, Reynolds and Thomas dimensionless numbers influence simultaneously the air phase extent. Thus, the present study connects the Rayleigh Plesset equation to turbulence and cavitation flow parameters. This allowed a new flow analysis through a venturi considered by its air phase development.

Water SA

Low-cost aerators relying on the venturi principle to entrain air into flowing water have the notable advantage of contributing both to water mixing and oxygen transfer, making them attractive for wastewater treatment in low-resource settings. This study aimed to characterize the performance of such aerators by describing the impact of different design characteristics, including water flow rate, the number of nozzles used, and the nozzle depth. The study also explored the effect on aeration performance of temperature, total dissolved solids (TDS) concentration, and addition of the archetypal surfactant sodium dodecyl sulphate (SDS). Tests were conducted in a 200 L reactor with 2, 3 or 4 nozzles, at depths of 20, 40 or 60 cm, while circulating water through the aeration device at a rate of 400, 600 or 800 L/h. The configuration that yielded the highest mass transfer coefficient (KLa20 of 20.8 h-1) had both the highest flow rate (800 L/h) and the smallest number of nozzles (2). Nozzle...

Maǧallaẗ al-baṣraẗ li-l-ʻulūm al-handasiyyaẗ, 2023

There is a vacuum created when water goes past a pipe constriction. Air may be pulled into the main flow by drilling a hole in the pipe near where the vacuum happens. Venturi aerator is an example of the application in action. A vacuum is formed at the suction holes of the Venturi tube when there is a small difference in pressure between the input and output sides. To demonstrate the link between total flow rate and Venturi aerator performance, a Venturi aerator (model 1584) was introduced at a specific point in a Biopipe system. For this purpose, a physical model on a pilot scale was constructed and installed in an existing sewage treatment plant. Dissolved oxygen concentrations were measured at four locations along the Biopipe at different values of wastewater flowrates. The study results showed that raising the total flow rate increased the amount of air injected by the Venturi aerator. When the total flow rate was less than 4 m 3 /hour, the Venturi aerator stops sucking air and produces negative consequences.

Jet pump is a type of mechanical device where the extra energy is provide by jet in mixing chamber. This jet is the fluid again circulate from diffuser exit to mixing chamber for better performance. This is also known as motive fluid. So the effects of change in geometrical parameter (Diffuser angle) on its performance were investigated. The set of experiment were carried out to study the effect of diffuser angle on the performance of jet pump. The performance of the jet pump is described by three sets of curves, Discharge vs. Head, Input power vs. Head, and Efficiency vs. Head. Changing the diffuser angle will affect jet pump behavior. Venturi diffuser angle was found to be an important geometrical parameter to characterize the maximum suction lift of the jet pump.

2013

One of the most important parameters to determine the quality of water is the amount of thedissolved oxygen (DO) in water body. Microorganisms as bacteria need high concentration ofoxygen in water to the able to continue their lives healthfully. In this case, the concentration ofthe dissolved oxygen in water body should be greater than 5 mg/L. The hydraulic jump is usedas an effective natural mechanic mixer for the oxygen transfer from air to water body.This study is aimed to investigate the aeration efficiency created by the water jet verticallyon the turbulence shear layer in hydraulic jump. The experiments have been realized in an openchannel having a width of 0.4 meters, a height of 0.65 meters and a length of 12 meters. Thedissolved oxygen has been measured using by a DO200 hand type oxygen meter. Experimentsare taken account five different jet flow rates and Froude numbers with in the range of 1 Fr =3.55-6.07 in the study.

Producto de la tesis de maestría Esteban de Oro - Univerisdad del Norte, 2021

This work presents an experimental evaluation of a Venturi and Venturi-Vortex microbubble aeration system, taking as input variables the water-air flow ratio, water renewal time and area-volume ratio of the water tank. The aeration process response variables are defined in terms of oxygen transfer and aeration efficiency through the standard volumetric mass transfer coefficient (K L a 20), standard oxygen transfer rate (SOTR), and standard aeration efficiency (SAE). Two methods of air injection were analyzed: 1. Air injection in the throat chamber of the Venturi generator; 2. air supplying in the suction side of the hydraulic pump of the aeration system. Experimental results indicate that the water renewal time variable (RT) is a statistically significant factor with respect to the K L a 20 , which can be maximized by decreasing RT. The effects of the variable flow ratio (FR) are greater than the effects of renewal time and area-volume ratio (AVR) concerning SOTR and SAE, indicating a maximum response with a minimum flow ratio, using the Venturi-Vortex microbubble generator. When the flow ratio decreases, the air flow increases, generating and transferring a greater amount of microbubbles (MB) into the water. It was found that increasing the air flow produced an increase in the standard oxygen transfer rate SOTR and standard aeration efficiency SAE. Results allow concluding that the injection of the air flow from the suction side of the pump promotes the generation of microbubbles (MB) for a maximum air flow allowed by the system. SOTR and SAE could be maximized whit the flow ratio factor and the Venturi-Vortex generator, supplying air flow from the suction side of the hydraulic pump.