Every day we receive dozens of questions from our customers, the answers to which, in one way or another, rest on the efficiency of the Green Stream aerator and the amount of oxygen with which it can saturate the water. We have conducted dozens of tests, worked with different bodies of water and rely solely on experience in the field. Therefore, in order to provide our customers and everyone who is interested in the issue of water saturation with oxygen, reliable data on the efficiency of the Green Stream aerator, we decided to conduct test runs of the aerator.
Unfortunately, we could not find ideal conditions for the experiment – a pool with a volume of 100 m3 or more with the ability to change the chemical composition of water, and we decided to conduct our measurements on natural reservoirs. And we agreed to conduct experiments in cooperation with the Institute of Fisheries NAASU (National Agrarian Academy of Sciences of Ukraine).
Methodology for calculating the power of the aerator
The Institute allocated us with two fishing lakes for tests:
- The lake has an area of 0.1 hectares, an average depth of 1.7 meters. The volume of the reservoir is about 1700 m
- The lake has an area of 0.6 hectares, an average depth of 1.2 meters. The volume of the reservoir is about 6000 m3.
It was decided to conduct two measurement sessions as follows:
- Turn on the aerator at fixed intervals
- Measure the oxygen level in water
- Calculate the power of the aerator based on the difference in readings
The calculation of the mass of oxygen transferred to water is calculated by the formula:
M_{o2}=V*ΔQ, where:
M_{o2} – oxygen mass in kg
ΔQ – difference in oxygen content in water between sessions
V – oxygen volume in м^{3}
The performance of the aerator is calculated as the ratio of the amount of oxygen transferred during the operation of the aerator.
P = M_{o2}/t, where:
M_{o2} – oxygen mass in kg
t – time between sessions
Performance per kW is calculated as the ratio of performance to electricity consumption per hour.
P_{0} = P/E, where
P – aerator’s power
E – energy consumed per hour, in kW
The Standard Aeration Efficiency (SAE) of our unit will be calculated using correction factors based on starting oxygen and water temperature.
SAE = P_{0} / K, where:
К – we take from the table of coefficients, depending on the starting saturation and water temperature.
We do not take into account the biological consumption of oxygen by the reservoir.
The water temperature during measurements was 22 degrees C.
Field trials: lake 0.1 ha
For the test we used a 1.5 kW SC1500 aerator. The first test was to be carried out on the lake of 0.1 hectares in the morning of July 7, 2020, but nature made adjustments – it was raining, which after 2 hours of waiting in the car turned into a downpour.
Realizing that because of the rain, which increases the oxygen content in the water, we will not get a clean experiment, the test run had to be postponed.
We returned to the facility on Thursday, July 09, took control measurements of the starting oxygen values and installed an aerator and spent 2 sessions of 3 hours each.
As a result of 6 hours of operation of the aerator on the lake, the amount of oxygen increased almost 2 times!
Measurement and calculation of the amount of oxygen transferred to water
Session | Oxygen content, mg / l | Difference between sessions, mg / l | Oxygen saturated, kg |
Q_{n} | ΔQ | M_{O2} | |
Start | 4,02 | ||
1 session | 6,05 | 2,03 | 3,52 |
2 session | 7,51 | 1,46 | 2,53 |
Performance calculation results
Session | Performance, kg / hour | Performance, kg / hour / kW |
P | P_{0} | |
1 session | 1,17 | 0,78 |
2 session | 0,84 | 0,56 |
Effective performance and SAE calculation results
Session | Performance, kg / hour / kW | K | SAE |
1 session | 0,78 | 49% | 1,6 |
2 session | 0,56 | 30% | 1,88 |
The average SAE in this reservoir was 1.74 kg O2 / h / kW
Field trials: lake 0.6 ha
We carried out the second test on a 0.6 hectare lake the next day, Friday, July 10, 2020. This time we arrived a little earlier – we planned to increase the aerator operation time to 10-12 hours.
The weather was favorable, and the work was carried out in a calm, spiritual mood. We got 2 working sessions of 5 hours each. In total, our device worked for 10 hours, we raised oxygen 1.5 times from the starting values.
Measurement results and calculation results
Session | Oxygen content, mg / l | Difference between sessions, mg / l | Oxygen saturated, kg |
Start | 5,68 | ||
1 session | 7,05 | 1,37 | 8,22 |
2 session | 7,76 | 0,71 | 4,26 |
Performance calculation results
Session | Performance, kg / hour | Performance, kg / hour / kW |
Start | ||
1 session | 1,64 | 1,10 |
2 session | 0,85 | 0,57 |
Effective performance and SAE calculation results
Session | Performance, kg / hour / kW | K | SAE |
1 session | 0,78 | 49% | 1,6 |
2 session | 0,56 | 30% | 0,88 |
The average SAE for this pond was 2.67 kg O2 / h / kW
Conclusions on the effectiveness of the Green Stream aerator
In total, in two dimensions, we can summarize that:
- Average SAE of the aerator 2.2 kgO2/h/kW
- Oxygen assimilation is volume dependent, i.e. on a larger body of water, oxygen transfer to water will be higher due to the larger volume of unsaturated water
- Taking into account the BOD (Biological Oxygen Demand) of the reservoir, the calculated performance of the aerator is slightly underestimated.
In conclusion, we want to thank the Institute of Fisheries of the NAASU for active cooperation and the provided landfill.
Green Stream Team