Introduction

Recent years have brought to light the escalating impact of global warming on water resources and their quality. Among the paramount parameters defining water quality in rivers, lakes, and reservoirs, dissolved oxygen concentration has emerged as a focal point (Boyd 1998). Aeration, whether through natural or artificial means, remains the primary method for bolstering oxygen levels in aquatic environments (Kahil and Seif 2014; Mahmad et al. 2015).

Aeration, characterized by the infusion of atmospheric oxygen into water through bubbles, plays a pivotal role in efficiently enhancing dissolved oxygen (DO) concentration while facilitating the removal of dissolved gases such as CO2, H2S, volatile organic chemicals (VOCs), and metals (Kahil and Seif 2014; Mahmad et al. 2015). While natural aeration relies on atmospheric diffusion and plant photosynthesis, the burgeoning demands of intensified aquaculture underscore the need for artificial aeration methods to meet the escalating demand for dissolved oxygen (Boyd 1998).

Artificial aeration encompasses diverse techniques, including the utilization of compressors, hydraulic systems, or fountains, to oxygenate water bodies (Roy et al. 2017; Cheng et al. 2019). These systems play a critical role in water circulation and oxygenation, crucial for sustaining a healthy aquatic ecosystem (Adel et al. 2019; Roy et al. 2020a). Pond aeration, in particular, serves as a cornerstone for sustaining aquatic environments and supporting diverse species (Boyd 2017; Boyd and McNevin 2020).

Over the years, various types of artificial aerators have been developed to enhance aeration efficiency. In aquaculture, propeller-aspirator-pump aerators, vertical-pump aerators, diffused aeration systems, and paddle wheel aerators have found widespread application (Kumar et al. 2013a). Economic analyses suggest that propeller-aspirator-pump aerators are more economical for smaller ponds, whereas paddle wheels offer cost-efficiency for larger pond sizes (Kumar et al. 2013b). Cascade aeration systems emerge as economical choices for ponds with smaller water volumes (Kumar et al. 2013a). Furthermore, attention is drawn to subsequent studies aimed at providing a deeper understanding of the effectiveness and economic advantages of different types of aerators for aquaculture (Roy et al. 2021, 2022).

In the realm of artificial aeration, hydraulic structures play a pivotal role by introducing a large volume of air bubbles into water, thereby enhancing oxygen transfer efficiency (Tuna et al. 2014). This method stands out for its economic advantages, characterized by lower energy consumption and higher oxygen transfer efficiency (Aytac and Tuna 2023).

Recently, significant research activities have been carried out on conduit designs and their evaluation in terms of aeration performance. Despite these studies on conduits, there has not been a full-fledged investigation on the performance and unit energy cost of these systems in terms of their applicability in aquaculture facilities or ponds. In this study, the effects of the physical parameters of the conduit on aeration performance and energy cost under different flow conditions were comprehensively investigated. In order to select the most suitable type of conduit, alternatives that provide high ventilation performance with low energy cost were identified. This research holds promise for providing viable alternatives in aquaculture facilities utilizing recirculating systems, potentially reducing operational costs and enhancing profitability through optimized aeration strategies. Therefore, the findings of this study will help the users to select the best conduit design according to their requirements in facilities that will provide ventilation with hydraulic structures.

High-head gated conduit

Hydraulic systems achieve two-phase flow systems by various methods of taking air from the atmosphere into high-pressure conduits. The smaller the sizes of air bubbles transferred into these systems, the greater the surface area required for oxygen transfer increases. Oxygen transfer increases due to the increase in surface area. Additionally, the high pressure inside the conduit facilitates oxygen transfer (Aydin et al. 2023).

In covered conduits, water passing rapidly under the cover causes a lower pressure to form at the downstream side of the cover compared to atmospheric pressure. Due to this low pressure, air enters the conduit through an air inlet pipe immediately downstream of the cover. Air vacuumed from the atmosphere mixes with water in the form of bubbles. Introducing air into the flow not only accelerates oxygen transfer but also reduces cavitation damage, limits vibration effects, and stabilizes flow conditions. Two-phase flow regimes that may occur at the cover downstream in covered conduits are illustrated in Fig. 1.

Fig. 1
figure 1

High-head gated conduit flow (Tuna et al. 2014)

Full size image

Recirculating systems

“Recirculating systems” used in aquaculture essentially refer to a common technology aimed at cultivating fish or other aquatic organisms by reusing water in production. This method, in principle, can be utilized for the cultivation of any type of aquatic product, such as fish, shrimp, and oysters. The use of recirculating systems is rapidly increasing in various sectors of the aquaculture industry, and these systems are employed in the following production units. The locations where these systems are used vary widely, ranging from large facilities producing tons of fish to small, sophisticated systems used for restocking or rescuing endangered species (Bregnballe 2022).

In these systems, recirculation can be carried out at different intensities depending on how much water is recirculated or reused. In traditional systems, for example, for every kilogram of fish produced in fish farming areas aerated using traditional methods, there is a need for 30 m3 of new water. In recirculating systems, for every kilogram of fish produced, the need for new water can be reduced to as low as 300 L. This represents approximately a 100-fold water saving compared to traditional systems. Furthermore, if denitrification and phosphorus removal are integrated into the recirculating system, water consumption can be further reduced, with the water requirement per kilogram of fish produced being reduced to as low as 30–40 L. Due to the intense biological activity in the farming areas, there is a high concentration of CO2. CO2 is removed only through the aeration of water, so the gas removal process occurs automatically during recirculation. Therefore, efficient aeration must be ensured in recirculating production areas (Bregnballe 2022).

Taking into account the effects of global warming and climate change, water and energy have become limited resources in many regions. In this context, recirculating farming areas can be considered the most environmentally friendly way to commercially produce fish. It is a fact that water conservation provides significant benefits to production within fish farms. Traditional fish farming is entirely dependent on external factors such as river water temperature, water cleanliness, and oxygen levels. In a recirculating system, these external factors are either completely or partially eliminated depending on the degree of recirculation and the structure of the facility. A facility with an effective aeration system will provide significant water and energy savings. This will not only increase producers’ competitiveness in the market but also significantly reduce operating costs for businesses.

Materials and methods

In this experimental study, the effects of physical parameters such as hydrostatic water levels, immersion angles of the air–water jet injecting into the pond, different gate opening ratios, and water flow rates, which directly affect the performance of a new type of pond aeration system, on air intake efficiency and aeration cost were investigated to determine the performance of the system. Tap water was used in the experiments. The presence of floating materials, organic matter, and suspended solids in tap water, which could adversely affect air intake efficiency, was not observed.

All components used in the experimental setups are shown in Fig. 2. Firstly, the system was set to recirculate mode. Water drawn from the system was reinjected into the system using a pump. Meanwhile, the volume of water drawn was determined by passing it through an electromagnetic flow meter. The velocity of air passing through the conduit aeration hole was determined using high-precision anemometers. Multiplying the hole air by the air velocity yielded the volume of air entering the system. The duration of this process and the energy consumed by the pump were calculated. With the duration and air volume, the unit aeration cost was calculated. Additionally, the ratio Qa/Qw, indicating aeration performance, was determined. The velocity of the air entering the conduit is affected by variables such as valve opening (K), hydrostatic level (H), jet plunge angle (α), and flow discharge (Qw). In addition, the experimental tank in Fig. 2 (downstream) represents the circular cross-section pond used in the study, which is very important in terms of providing the most suitable environment for fish farming.

Fig. 2
figure 2

General view of the experimental setup

Full size image

A circular cross-section tank has been envisaged for the system. The environment in the fish farming tank should meet the needs of the fish in terms of both water quality and tank design. Selecting the correct tank design, including dimensions, shape, water depth, and self-cleaning ability, can have a significant impact on the performance of the species being cultivated. In a circular tank or a square-shaped tank, water moves in a circular pattern, allowing the entire water column of the tank to move around the center. Due to this hydraulic model that provides a self-cleaning effect, organic particles have a relatively short waiting time, typically a few minutes, depending on the tank size. A horizontally adjustable vertical inlet is an effective way to control flow in such tanks.

In order to fully observe the air bubbles entering the system and to determine the paths followed by these bubbles, an opening was left in each experimental setup. This opening is one quarter of the diameter of the pool in each. This opening was covered with 10 mm tempered transparent glass along the pool height.

To experimentally investigate the effect of hydrostatic water level, three different levels were determined based on the center of the jet plunge angle and the cells were filled with water up to these levels. The first level was studied as unsubmerged, the second level as H ¼ submerged and the third level as H ½.

In addition, as shown in Fig. 3, at 3/4 of the height from the pond bottom (hydrostatic level), there are three separate entrance halls connected to the pond at angles of 30°, 45°, and 60°. These connections were produced to adjust the plunge angle of the air–water jet entering the pond and the penetration depth of the jet. The pond is also constructed 50 cm above the bottom and a drain gate is installed to allow waste discharge.

Fig. 3
figure 3

Inputs 1–2 and 3 that provide different air–water jet plunge angles in the pond

Full size image

A galvanized metal pipe with a circular cross-section, 8.09 cm diameter, and 200 cm length was used to provide air intake to the system. The opening rate of the conduit cover is 10%, 30%, and 40%. An air pipe with a diameter of 14.00 mm was opened downstream of the conduit cover and the outdoor air was allowed to enter the pipe from there. A high precision anemometer was used to measure the velocity of the air sucked into the pipe (1.5% mv + %). The data was collected until a complete recirculation to calculate the air velocity drawn into the system. The average air velocity measured in the air inlet pipe was multiplied by the area of the air inlet pipe to calculate the air flow rate. The parameters used in the experiments are given in Table 1.

Table 1 Experimental alternatives
Full size table

Three different gate reduction ratios were used to determine the effect of the gate reduction on the air intake. The radius of the radial gate was selected considering the required gate height at the smallest gate opening ratio. The gate radius was determined as the maximum value of the gate height (h1) measurement, which is indicated in Fig. 4, and was determined to be 74.9 mm. The same curvature was used for all gate opening ratios. The experiments were conducted using different flow rates. Based on these flow rates, the water velocity under the gate was calculated.

Fig. 4
figure 4

Circular cross-section conduit gate opening ratios

Full size image

Monitoring and recording were carried out on the tempered glass part of the pool surface area. Parameters such as air bubble density, air bubble size and dead zones, where air bubbles do not reach the pool, penetration depth, which is the last vertical distance reached by air bubbles, and the thickness of the foam layer formed on the surface were recorded with the help of high-resolution and high-speed cameras. These images were detected with professional image processing techniques.

In the study, the energy consumption of the system for each parameter was measured. Amperage and voltage were measured using an ammeter and voltmeter connected to the pump, thereby calculating the power consumed by the system. The measured values and the operating time were multiplied to determine the electrical energy consumed by the system. As a result of this process, the electrical energy consumed by the system was determined in kWh. The operating time was considered the duration required for one complete circulation of water in the tank. Thus, the volume of water drawn from the system, the volume of air added to the system, and the energy consumed by the pump during the circulation time were determined. Subsequently, the energy expended for this process was divided by the total volume of air introduced into the system to determine the cost per unit volume of air. Consequently, the time required for one complete circulation, equivalent to the volume of the pond in 1 m3, the volume of air introduced into the system, and the amount of electrical energy consumed were determined. Then, the aeration cost was calculated by determining the ratio of the consumed energy amount to the volume of air entering the system.

Results and discussion

In this study, the effect of experimental alternatives with different parameters on the pond air intake efficiency was determined, and systems providing the optimum (best) air intake efficiency were identified. Based on the determined optimum air intake efficiency, the energy costs of the new system were examined. To better understand the experimental results, grouping was performed according to the alternatives. Each group was further divided into subgroups.

The effect of gate opening on aeration performance

Figure 5 illustrates the relationship between the air intake flow rate and the water intake flow rate for different conduit gate opening ratios. It can be observed that as the water velocity increases, Qa also increases for all gate opening ratios. From this, it is understood that there is a direct relationship between water velocity and air intake efficiency. According to the Bernoulli equation, which is one of the fundamental equations of fluid mechanics, as a fluid moves from one point to another, it converts its velocity, pressure, and potential energy into one of these quantities and moves to a second point. In our experimental setup, since the flow moves along the same conduit axis, the gravitational height (z) remains constant, the velocity increases due to the narrowing of the cross-section, and consequently, the pressure drops significantly. In fact, negative pressure is often created at the gate outlet. To balance this negative pressure or pressure differential, the amount of air entering the system increases.

In the experimental study, the air intake efficiency reached its maximum value at a 10% gate opening ratio. As the gate opening ratio increased, the air intake efficiencies decreased. It can be observed that there is an inverse relationship between the gate opening ratio and air intake efficiency. The reason for this is that as the gate opening ratio increases, the pressure difference between the gate outlet and the outlet decreases. Due to the reduced pressure difference, the air intake efficiency decreases.

Fig. 5
figure 5

The effect of gate opening ratios on aeration performance

Full size image

The effect of air–water jet plunge angle on aeration performance

Upon examining the experimental groups depicted in Fig. 6, it can be observed that aeration performance reaches its maximum value in alternatives where the jet plunge angle is α = 60°. While there is not a significant difference in aeration performance among the alternatives, it is generally observed that as the air–water jet plunge angle decreases, the aeration efficiency tends to decrease as well. Therefore, it can be stated that there is a direct relationship between the water jet plunge angle and aeration efficiency. Additionally, in experiments corresponding to the jet plunge angle, alternatives with α = 60° exhibit the most optimal distribution of air bubbles within the tank.

In experiments corresponding to the water jet plunge angle, it was observed that air bubbles scanned almost the entire tank at α = 45° and α = 60° jet plunge angles, whereas at α = 30°, there were areas in the lower part of the tank where no air bubbles entered. Therefore, it can be concluded that the most suitable angle for the aeration process is α = 60°.

Fig. 6
figure 6

The effect of air–water jet plunge angle on aeration performance

Full size image

The effect of hydrostatic level on aeration performance

When examining all experimental groups depicted in Fig. 7, it can be stated that the maximum air entry performance is achieved in alternatives where the hydrostatic level is H = 0 cm. In the experimental groups, as the hydrostatic level increases, the amount of aeration decreases. In other words, there is an inverse relationship between the hydrostatic level and aeration efficiency.

Upon examining Fig. 7, it is observed that aeration performance increases nearly linearly in all alternatives where the jet submersion angle is α = 30°. Upon analyzing all experimental groups, it is observed that alternatives with no aeration generally occur in cases of low water volumes and a hydrostatic level of H = 50 cm.

The decrease in aeration performance with the increase in hydrostatic level can be explained as follows: As the static water level above the jet of the air–water mixture submerged into the pond rises, it creates pressure on the jet. Therefore, aeration performance is negatively affected by this situation, resulting in a decrease.

Fig. 7
figure 7

The effect of hydrostatic level on aeration performance

Full size image

Three-dimensional graphs comparing combined parameters

The relationship between gate opening (K) and jet plunge angle (α) with the air volume entering the system is shown in a three-dimensional graph in Fig. 8. Upon examining Fig. 8, it can be observed that as the gate opening ratio and angle decrease, the air intake rate is maximized. In experiments with low gate openings, keeping the opening constant while increasing the angle tends to decrease the air intake rate. Conversely, in the case of large gate openings, the situation is reversed.

Fig. 8
figure 8

Three-dimensional analysis of air volume, gate opening ratio (K), and water jet plunge angle (α)

Full size image

The three-dimensional graph depicts the relationship between the hydrostatic level and the volume of water injected into the pond with the air volume entering the system. Figure 9 reveals that as the hydrostatic level increases, the air intake performance decreases. Conversely, when the volume of water injected into the pond increases, the air intake rate maximizes. The air intake performance is minimized with low water volumes and high hydrostatic levels. It can be inferred that increasing the volume of water injected into the system reduces the submergence effect. Particularly in experiments with a high volume of injected water, submergence becomes less effective.

Fig. 9
figure 9

Three-dimensional analysis of air volume, hydrostatic level, and water volume

Full size image

The three-dimensional graph in Fig. 10 illustrates the relationship between the gate opening and the volume of water injected into the pond with the air volume entering the system. Upon examining Fig. 10, it is evident that the air intake rate maximizes with increasing gate opening and water volume. Particularly in experiments with small gate openings, increasing the volume of water injected into the system significantly enhances the air intake performance. In experiments with large gate openings, the air intake rate remains constant with increasing water volume, showing no change. This graph strikingly demonstrates that the gate opening is a highly influential parameter on air intake performance.

Fig. 10
figure 10

Three-dimensional analysis of air volume, gate opening ratio (K), and water volume

Full size image

The three-dimensional graph in Fig. 11 illustrates the relationship between the angle of submergence of the water jet and the volume of water injected into the pond with the air volume entering the system. Upon examining Fig. 11, it is observed that there is an inverse relationship between the angle of submergence and air intake performance. In experiments with low submergence angles, increasing the volume of water injected into the pond maximizes the air intake rates. However, in experiments with high submergence angles, increasing the water volume does not affect the air intake performance, and it remains constant.

Fig. 11
figure 11

Three-dimensional analysis of air volume, water jet plunge angle (α), and water volume

Full size image

Energy cost, specific power, and efficiency: analyzing key metrics in pond aeration systems

When calculating the operational costs of aeration systems, it is worth noting that electricity consumption constitutes the majority of expenses (about 80%). As energy accounts for most of the operational costs, investing in the most efficient aeration method is logical. Therefore, in our study, the energy costs of the newly developed system have been assessed for each experimental alternative. Consequently, the optimum dimensions and components of the aeration system, which minimize energy costs while maximizing aeration performance, have been identified.

Specific power [kW/1 m³/min] or specific energy [kWh/m³] is an indicator of system efficiency. An inefficient system requires more energy to produce a certain amount of air. Therefore, production will be costly for such an aeration system. The real specific energy of aeration systems cannot be obtained from datasheets because datasheet values are given theoretically, and real electricity consumption should be measured under actual conditions. Since there are multiple parameters that affect specific power or energy, and these parameters change over time, efficiency should be monitored regularly. Compressors are commonly used in ponds and fish farming areas. The specific energy of a compressor considered efficient should be approximately below 0.15 kWh/m³.

Additionally, specific energy consumption (SEC) is considered in the evaluation of energy efficiency of aeration systems. SEC for an aeration system can be determined by dividing the energy consumption (kWh) under nominal load by the volume of air produced (m³). Table 2 provides an assessment of energy efficiency based on the SEC value of a compressor.

Table 2 Assessment of energy efficiency based on compressor SEC value (Dindorf 2012)
Full size table

Dindorf (2012) investigated the energy efficiency assessment of compressors commonly used in aquaculture aeration and determined the unit aeration costs of compressors. According to this study, the unit aeration cost is 1.30 kWh/m3 of air. Compressors with energy consumption below 1.30 kWh/m3 of air are characterized as machines with high energy efficiency. This value was found to be 0.10 kWh/m3 of air in our most appropriate test alternative in conduit design. When compared with compressors, it is evident that this value is significantly lower.

Moreover, different types of aerators were selected based on their aeration performance with the proposed high-head conduit for aeration cost assessment. In their experimental study, Yadav et al. (2022) determined the amount of energy consumed in kgO2/kWh by aerators such as paddle wheel, Venturi jet, and aspirating aerator. These values are 3.48, 1.66, and 3.72, respectively. If a comparison is made with the head gated conduit, which is the subject of this study, it is found that it is necessary to spend 0.10 kWh of energy for 3.20 m3 of air at the optimum value of the experimental study. There is approximately 1.355 kg of O2 in 1 m3 of air. Therefore, the high-cover conduit has a performance of around 4.3 kgO2/kWh. With these values, conduits exhibit a good cost-performance relationship compared to both compressors and other artificial aerators.

The table below presents the evaluation of energy efficiency, including the amount of air introduced into the system and the energy required for it, when a 1 m³ volume tank completes one cycle. Table 3 is prepared for scenarios where aeration performance is high among the experimental alternatives.

Table 3 Evaluation of energy efficiency for high aeration performance scenarios
Full size table

As seen in the table, there are experiment alternatives with particularly excellent and good energy efficiency evaluations. Especially in alternatives with a 10% gate opening ratio, the aeration performance is high and the energy cost is quite low. There are experiment groups categorized as “excellent” in terms of energy efficiency. As the gate opening ratio increases, the energy cost also increases. In all alternatives with a 40% gate opening ratio, energy costs have been calculated as high. This is an undesirable situation.

Additionally, with the increase in hydrostatic level at the same gate opening ratios, energy costs have slightly increased. It has been observed that the air–water jet plunge angle has no effect on energy costs.

If the developed system is designed based on alternatives at the good and very good levels in terms of specific energy consumption category, it will be able to perform the aeration process more efficiently and at a lower cost compared to many compressors.

Fig. 12
figure 12

Three-dimensional cost graph

Full size image

Figure 12 illustrates the three-dimensional graph showing the effect of gate opening and injected water volume on energy cost. As the gate opening increases, energy costs directly rise. Energy costs also increase with low gate openings and low water volumes. Energy costs are minimized with low gate openings and large water volumes. However, this occurs only up to a certain point of water volume increase. If the water volume is increased beyond a certain threshold, the cost starts to rise again. Energy costs are generally high for all alternatives with low water volumes.

Data analysis

In our experimental study, multiple regression analysis was conducted to investigate the effects of independent variables on the outcome. The analysis results are presented in Table 4..

Table 4. Data analysis results
Full size table

Upon examining the F values from the analysis of variance, it was found that the significance levels were much larger than the F value, indicating that the results obtained are significant depending on the variation of the independent variables. Furthermore, when examining the T-test results, the values being different from zero indicate the consistency of the results. The fact that all p-values are small (p < 0.05) when examining them indicates that the independent variables have an effect on the outcome. As evident from the p-values and percentage effect rates, the most influential variable was the gate opening ratio. Additionally, the correlation coefficient (R2) calculated to be 0.91 indicates the consistency of the results. The percentage effect sizes of the variables are depicted in Fig. 13.

Fig. 13
figure 13

Percentage effect sizes of variables

Full size image

Furthermore, based on the results of data analysis, a mathematical equation has been formulated to determine the volumetric air intake to the system, which encapsulates the relationship between dependent and independent variables (Eq. 1).

$$Qa=0.010039-0.00049\times K+(0.000079\times\alpha)-(0.00008\times H)+0.00088\times Qw$$
(1)

Study limitations

The findings of this study are based on experimental data obtained at a specific laboratory scale. The performance of the system in large-scale aquaculture ponds may vary. The study provides an idea of the energy cost of the aeration system. However, a comprehensive economic analysis, taking into account factors such as initial investment, maintenance costs, and payback period, should be carried out. Other factors, such as environmental impacts or long-term durability, should also be thoroughly investigated.

Conclusions

Global warming and pollution lead to dangerously low levels of dissolved oxygen in aquatic ecosystems. If left unaddressed, this poses a threat to aquatic life, especially in natural lakes, ponds, and pools. In this study, hydraulic principles were utilized for pond aeration. A series of experimental and observational studies were conducted to optimize a next-generation aeration system. Various parameters were investigated in these experimental studies, including gate contraction ratios, air–water jet plunge angles, injected water volumes, and hydrostatic water levels. The impact of each parameter on aeration performance and energy consumption was determined. The results obtained from the experimental studies are as follows:

  • The system’s aeration performance and energy efficiency are directly related to the gate opening ratio, hydrostatic level, and air–water jet flow rate. As the gate opening ratio increased in all experimental alternatives, the air intake efficiency decreased.

  • In all experimental alternatives with gate opening ratios of 30% or higher, it was observed that the impact of variables such as jet plunge angle and hydrostatic level on air intake efficiency decreased.

  • The most effective parameter on air intake performance is the gate opening ratio.

  • Increasing the hydrostatic water level generally decreases aeration efficiency.

  • The effect of the hydrostatic level is more effective, especially at low levels of injected water volume, while its effect decreases with increasing water volume.

  • The impact of immersion angle on air intake performance is negligible.

  • The best air intake efficiency was achieved in the alternative with a 10% gate opening ratio, a 60-degree immersion angle, and a hydrostatic level of 0. In this experimental condition, while 1 m3 was recycled from the system, 3.20 m3 of fresh air was added. The energy cost of this process was measured as 0.10 kwsa/m3.

  • There is a direct proportionality observed between aeration performance and energy cost.

  • When evaluated based on energy cost, increasing the hydrostatic level slightly increases the cost.

  • It can be said that the immersion angle of the air–water jet does not have a significant impact on cost.

  • Aeration unit with a very good status in terms of energy efficiency was developed based on the specific energy consumption value of the system.

The developed system provides a high influx of air bubbles into the pond, making it easy to achieve the significant amount of air bubbles desired for pond aeration. Systems designed with low nozzle openings and low hydrostatic levels will be highly advantageous both in terms of aeration performance and low energy costs. Additionally, the system is designed to be simple enough to not require annual maintenance and operation costs like a compressor. Therefore, it will provide significant economic benefits both in terms of energy and maintenance and operation costs. Due to these advantages, the system could be a good alternative to existing systems for pond aeration.

The widespread adoption of the aerating system, developed through research and operating with a simple method, in both artificial and natural water bodies, is crucial as it serves as a valuable tool in conserving water resources affected by greenhouse gas emissions and depletion. One significant advantage of the system is its ability to significantly mitigate pathogenic effects. Uncontrolled accumulation of carbon and high levels of nitrogen gas can adversely affect fish health and limit growth. However, the system’s high aeration performance effectively mitigates these gases.

The results of this study can be considered an important step in the design of a highly efficient alternative aeration system. The experimental studies allowed us to learn under which conditions it can be used effectively with low energy costs. The main findings of this study show that parameters such as flow rate, cover opening, hydrostatic level, and jet plunge angle affect the aeration performance. The optimal design was able to introduce more than three times the volume of air than the volume of water circulating in the system while keeping the energy cost to a minimum. These findings allow the determination of system sizes that reduce energy cost while improving aeration performance. The developed system has a very high energy efficiency based on the specific energy consumption value. Therefore, it can be a good alternative to existing systems.