Why use a dissolved oxygen meter?
Dissolved oxygen (DO) refers to molecular oxygen dissolved in water. The unit is mg/L, which is how many milligrams of oxygen there are in a liter of water. Oxygen content can reflect the self-cleaning capacity of water. In the DO high environment, is conducive to the degradation of various pollutants, so that water faster purification. In contrast, pollutants in water degrade more slowly in low-DO environments. Dissolved oxygen levels are affected by water temperature, air pressure and salinity. The higher the temperature, the lower the oxygen content. Dissolved oxygen value is the basis of studying the self-purification ability of water. In a flowing river, water samples are taken from different parts to determine oxygen content. You can understand the self-purification of the river at different locations. General water oxygen content of at least 4mg/L, good water quality. Oxygen content is also an important index in the process of wastewater treatment. Therefore, we can use the DO tester independently developed by JXCT for online monitoring.
What are the factors affecting dissolved oxygen?
The main factors affecting the level of dissolved oxygen in water are water temperature, salinity and atmospheric pressure.
How does temperature affect dissolved oxygen
As the temperature rises, the oxygen content gradually decreases. In fresh water, dissolved oxygen mainly comes from two parts: one is the oxygen released by plants during photosynthesis, accounting for about 60%. The other part is oxygen from the air dissolved in the water, which makes up about 40 percent. As the temperature rises, the Spaces between water molecules become smaller and oxygen in these Spaces is squeezed out, reducing oxygen levels. Normally, the concentration of dissolved oxygen in the water is lowest in the summer.
Anyone who has seen boiling water knows that bubbles form on the sides and bottom of the pan during heating. The number and size of bubbles increase with temperature. These are bubbles dissolved in water. We can think of water as a uniform medium. Its volume is dotted with holes. The air pressure above the water will fill these holes with air. So as the temperature rises, this air is forced to separate from the water molecules. These bubbles also contain oxygen, so oxygen levels are reduced.
How does salinity affect dissolved oxygen
As salinity increases, oxygen levels decrease. Because as the water becomes saltier, these salt molecules fill the Spaces between the water molecules. Which lowers the oxygen content. For example, if you put some fine sand in a bottle full of rocks, there will be less air in the bottle. Because fine sand fills the gaps between the stones.
How does air pressure affect dissolved oxygen
The greater the pressure, the more oxygen molecules can be pushed into the water, and the more oxygen there is in the water. The pressure from above allows the water to hold more oxygen molecules. Conversely, the lower the pressure, the more likely the oxygen in the water will escape. Dissolved oxygen is usually very low when the pressure is low, such as before rain, especially summer heavy rain.
Why is dissolved oxygen important?
Just as humans use their lungs to take in oxygen from the air, living things in water need to take oxygen from the water to survive. Dissolved oxygen is very important to aquatic life. Fish, invertebrates, crabs and other underwater animals use gills to get oxygen from the water. When there is no light for photosynthesis, algae and other phytoplankton need to consume oxygen to breathe. Bacteria, fungi and other microorganisms also consume oxygen when they decompose organic matter in the water. When there is enough oxygen in the water, the animals and plants in the water can grow healthily.
In a pond or river, oxygen levels fluctuate periodically and seasonally for natural ecological reasons. As the dissolved oxygen decreases, the fish move closer to the surface, or even poke their heads above water. If the lack of oxygen is severe, the fish can get sick or even die. Sufficient oxygen in water can inhibit toxic substances and effectively degrade toxic substances. When oxygen is insufficient, ammonia and hydrogen sulfide are difficult to decompose and transform, affecting water quality and biological health.
As water gets deeper, it contains less and less oxygen. This also creates species diversity. Different organisms are active in the water layer that suits them according to their own needs. Living creatures in the deep, such as crabs, oysters, needs less oxygen (1-6 mg/l), but fish live in the shallow water needs more oxygen ⁵ (4-15 mg/l).
Common DO tester equipment
Portable dissolved oxygen detector
Portable dissolved oxygen analyzer (determinator) is mainly used in laboratories, aquariums, aquatic product breeding, rice fields, swimming pools, etc. It is specially designed for the convenience of users to carry to the scene. The portable dissolved oxygen analyzer can be divided into two parts: the sensor and the electronic unit. The sensor adopts a tube-type coated dissolved oxygen electrode. The electronic unit is composed of high integrated circuits. The instrument uses a liquid crystal display, which can actually measure the dissolved oxygen, temperature, salt content and other values.
Dissolved oxygen sensor-DO meter&analyzer
Dissolved oxygen sensor, Dissolved oxygen meter，Dissolved oxygen analyzer is one of the intelligent online chemical analysis instruments. It can continuously monitor data through the transmission output and connect the recorder to realize remote monitoring and recording. It can also be connected to the RS485 interface through the MODBUS-RTU protocol for easy connection Enter the computer to realize monitoring and recording.
Dissolved oxygen meter
The dissolved oxygen meter is a sensing device used to measure the amount of oxygen dissolved in water. The continuous measurement of dissolved oxygen concentration in water plays an important role in the field of water treatment.The water quality dissolved oxygen sensor can be widely used in aquaculture, sewage treatment plants, environmental monitoring departments, fish ponds, factories and other fields.
How to increase dissolved oxygen in water?
When there is not enough oxygen in the water, it can have a bad effect on aquatic animals. Water quality deteriorates, affecting aquatic life. It is harmful to its growth, reproduction and survival. In light cases, physical decline, slow down the growth rate, and in severe cases, a large number of deaths. Therefore, in aquaculture industry, monitoring oxygen content, timely oxygenation is very important.
1.Biological oxygenation
Aquatic plants can produce oxygen through photosynthesis and add it directly to the water. This is the most economical and scientific method. It uses natural methods to increase oxygen in the pond and does not affect living things. Chloroplasts in plant cells use light energy to convert carbon dioxide and water into glucose and oxygen. Therefore, oxygen is increased by adding algae to the water. Add nutrients needed for algae blooms to the water regularly. Promote algae growth and reproduction. Using this method to increase DO requires consideration of adequate sunlight and nutrients. Because when there is enough light, water plants can only photosynthesize. At night or when there is no light, plants breathe and use up oxygen in the water.
2.Physical oxygenation
Air is constantly pumped into the water using machinery and equipment such as aerators. Increase the contact area between water and air, so that air can better combine with water, and increase the oxygen content of water. Or directly transport air to the bottom of the pool to increase the contact area and contact time between air and water. Let it dissolve more. Add fresh water sources to increase dissolved oxygen in the water. On a sunny afternoon, turn on the oxygenator to get the water flowing. Stir some of the oxygen-consuming material at the bottom to the upper middle layer and let it oxidize and decompose, reducing the oxygen consumption at the bottom.
3.Chemical oxidation
Sprinkle your pond with oxygenating tablets, hydrogen peroxide, and some surfactants to increase the amount of oxygen in the water in a short time. This method is suitable for emergency situations where the water body is severely hypoxic and there is no oxygenator.