Dissolved oxygen (DO) is the amount of oxygen dissolved in water, expressed in milligrams of oxygen per liter of water. Oxygen dissolved in water is called dissolved oxygen, and dissolved oxygen exists in water in a molecular state. The amount of dissolved oxygen in water is one of the important indicators of water quality, and it is also one of the important factors of water purification. High dissolved oxygen is conducive to the degradation of various pollutants in the water body, so that the water body can be purified quickly; on the contrary, the dissolved oxygen is low.

Dissolved oxygen content in water is generally affected by two kinds of effects: one is to reduce the oxygen consumption of DO, including the oxygen consumption of aerobic organic matter degradation, biological respiration and oxygen consumption; the other is to increase the reoxygenation of DO, mainly the dissolution of oxygen in the air, the photosynthesis of aquatic plants and so on. These two effects of the mutual growth and decline, so that the dissolved oxygen content in water presents a temporal and spatial variation.

After the water is polluted by organic matter, it is oxidized by aerobic bacteria and consumes dissolved oxygen. If the oxygen in the air is not replenished in time, the dissolved oxygen in the water will be reduced, which will eventually lead to the deterioration of the water body. So the dissolved oxygen as an indicator of the degree of water pollution. The less dissolved oxygen, the more serious the degree of pollution.

At present, the use of aerobic microbial treatment of industrial wastewater has been more common, and aerobic microorganisms must be under aerobic conditions to make organic matter decomposed into carbon dioxide, water, nitrate. In the treatment of industrial wastewater by the activated sludge method, the amount of dissolved oxygen DO (free oxygen dissolved in the treated water) is usually measured to properly adjust the oxygen of microorganisms. General industrial wastewater does not contain dissolved oxygen, often with the help of a variety of aerator flushing to meet the oxygen supply of microorganisms. The action of dissolved oxygen provides not only the formation of activated sludge (cell synthesis), but also the oxidation of the cellular material itself (bone-derived respiration) and the metabolism of microorganisms to oxidize and decompose the organic matter. Activated sludge treatment of industrial wastewater in the aeration zone generally dissolved oxygen control in (2~4)mg/L (aeration zone, middle and lower dissolved oxygen general error is not more than 0.5mg/L). Dissolved oxygen too high or too low will affect the metabolism of microorganisms and reduce the effect of water treatment.

Dissolved oxygen is too high (greater than 4mg/L) will accelerate the consumption of organic matter in sewage, so that microorganisms due to lack of nutrition caused by the aging of activated sludge, filamentous bacteria multiply. Long-term high dissolved oxygen will reduce the flocculation performance and adsorption capacity of activated sludge. Dissolved oxygen is too low (less than 1.5mg/L) will inhibit the life activities of microorganisms, leading to the decline, disintegration and deterioration of microorganisms; Affect the respiration of microorganisms and the purification capacity of activated sludge, sludge floating, decay until expansion.

Therefore, in industrial wastewater treatment, the monitoring of dissolved oxygen DO is very important.So how to detect dissolved oxygen? Below to recommend a dissolved oxygenSensorKDS-25Bto help you easily solve this problem

Dissolved oxygen sensorKDS-25B profile:The KDS-25B is an electrochemical dissolved oxygen detection sensor introduced by Japan's FIGARO company. It does not require preheating or external power supply. The output signal is linear with dissolved oxygen content. It has a built-in temperature compensation circuit and can be directly put into water.

Dissolved oxygen sensor KDS-25B basic parameters:
① Range: 0-80mg/L;
② Atmospheric pressure: 81-203kPa;
③ Temperature/humidity range: 5-35 ℃,10-90% RH;
The thermal constant of the thermistor: about 10 minutes;
⑤ Response time: T90 is about 20S,T100 is within 60S;
The first output in the air under standard conditions: 8-15mV;

Dissolved oxygen sensor KDS-25B main features:
1) Not affected by CO2 and other acidic gases;
2) Long life (life expectancy of 3 years);
3) High accuracy (± 5% full scale);
4) Built-in thermistor for temperature compensation;
5) no preheating, no external power supply;

Dissolved oxygen sensor KDS-25B typical applications:
1) the aquaculture industry;
2) On-line environmental monitoring;
3) Water source monitoring and sewage treatment industry;
4) Investigation of water pollution in education and scientific research fields;