What Factors Affect The Measurement of Dissolved Oxygen in Water?

2021-11-21

What is a Dissolved Oxygen Meter (DO)?

Dissolved oxygen is a measure of the amount of gaseous oxygen contained in water. Healthy waters that can support life must contain dissolved oxygen (Dissolved oxygen).

Dissolved Oxygen enters the water by:

direct absorption from the atmosphere.
rapid movement from winds, waves, currents, or mechanical aeration.
aquatic plant life photosynthesis as a by-product of the process.

What factors affect the measurement of dissolved oxygen in water?

Atmospheric pressure sensor: Higher atmospheric pressure allows bodies of water to retain more dissolved oxygen. The pressure from above allows the water to hold more oxygen molecules. Therefore, Dissolved oxygen concentrations are normally lower at higher elevations due to lower atmospheric pressure.

Temperature: A body of water with a lower temperature can contain more dissolved oxygen because oxygen molecules have less movement. The increased movement of oxygen molecules in warmer water allows them to escape out of the water into the air.

Depth of the water: The shallower the water, the higher the concentration of Dissolved oxygen because wind creating waves on the surface increases Dissolved oxygen, as well as aquatic plants living in shallower light-filled waters create Dissolved oxygen as a by-product of photosynthesis.

Salinity: Lower salinity contributes to a higher concentration of Dissolved oxygen because salts affect the solubility of gases, essentially driving them out of the water.

Bioactivity: Lower bioactivity of microorganisms in water leads to a higher concentration of Dissolved oxygen because microorganisms feeding on organics and decaying matter use oxygen in their respiration.

Why Monitor Dissolved Oxygen in water?

Measuring dissolved oxygen in water and treatment to maintain properly dissolved oxygen sensors, are crucial functions in a variety of water treatment applications. While dissolved oxygen is necessary to support life and treatment processes, it can also be detrimental, causing oxidation that damages equipment and compromises the product. Dissolved oxygen affects:

Quality: The Dissolved oxygen concentration determines the quality of source water. Without enough Dissolved oxygen, the water turns foul and unhealthy affecting the quality of the environment, drinking water, farming, agriculture, and others.

Regulatory Compliance: To comply with regulations, industrial wastewater treatment often needs to have certain concentrations of Dissolved oxygen before it can be discharged into a stream, lake, river, or waterway. Healthy waters that can support life must contain dissolved oxygen.

Process Control: Dissolved oxygen levels are critical to controlling the biological treatment of wastewater, as well as the biofiltration phase of drinking water production. In some industrial applications (e.g. power production) any Dissolved oxygen is detrimental for steam generation and must be removed and its concentrations must be tightly controlled.

At BOQU water quality analyzer Instrument, find the water quality meter monitoring equipment, resources, training, and software you need to successfully monitor and manage dissolved oxygen levels in your specific process application.