The Importance Of Electrical Conductivity Of Wastewater

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Electrical conductivity (EC) measures how many dissolved substances, chemicals, and minerals are in the water. Wastewater treatment facilities rely on measuring electrical conductivity to control which treatment process will be the most successful to remove contaminants and impurities. 

The wastewater treatment industry is essential to preserve the environment and protect public health. Wastewater treatment facilities remove pollutants/contaminants from wastewater so that the water can be returned to the water cycle. Once the water has been discharged back into the environment, it can be stored in aquifers and used for various purposes, such as for drinking water supplies. 

To successfully remove contaminants from wastewater, the electrical conductivity of water is measured. Electrical conductivity (EC) is essential for industries and applications to improve the quality of water. To measure EC in wastewater, an electrical conductivity sensor is used. 

What Is Electrical Conductivity?

Electrical conductivity refers to the ability of water to conduct an electrical current in a solution over a certain distance, usually measured in Siemens (S) per distance. The power for water to conduct electricity comes from the ion concentration within the water, which comes from dissolved solids and inorganic materials like carbonate compounds, chlorides, and sulfides. The conductance level also depends on the ion’s potential to bind with water.

Pure water has a low conductivity (usually 5 mS/cm or less) because of the lack of impurities. For water to conduct electricity, there must be ions present. When pollutants and contaminants are present in the water, it alters the electrical conductivity. 

For example, water that contains ions such as sodium, chloride, calcium, and magnesium will have a higher electrical conductivity than treated water. This happens because conductivity increases as water dissolve more ionic compounds. It is the ions that are present in the water that transports an electrical current in the solution.

The main measurement of electrical conductivity is microSeimens per centimeter (mS/cm), however, no matter which industry you are working in or which measurement you use, measuring the EC of water will determine if the EC levels are too high or low. Once the conductance of water is measured, you can decide the best way to adjust it. 

To understand EC measurements in a range of applications and industries, we can compare approximate EC values in different water bodies with the table below:

Water TypeElectrical Conductivity (mS/cm)
Distilled Water0.5-3
Tap Water50-800
Potable Water (US) 30-1500
Freshwater Streams100-2000
Industrial Wastewater10,000
Seawater 55,000

Why Is Electrical Conductivity Important In Wastewater Treatment Facilities?

Electrical conductivity is essential for wastewater systems, as it tells you how many dissolved substances (total dissolved solids: TDS), chemicals, and minerals water contains. The more impurities in the water, the higher the conductivity. It is critical to mention, that even small amounts of contaminants are enough to change the electrical conductivity in wastewater. 

In wastewater treatment facilities, changes in electrical conductivity indicate that pollutants are present in the water. Although measuring EC cannot tell us what type of pollutant is in the water, it will identify that there is a problem.

Measuring electrical conductivity in wastewater can also indicate a sewage leakage. For example, a failing sewage system often raises the conductivity of water due to the presence of chloride, phosphate, and nitrate.

What Affects Electrical Conductivity?

Many distinctive factors affect the conductivity of water. The most common factor is temperature; as temperature increases in water, EC increases, and vice versa. For example, if the temperature of water increases by 1℃ (33.8 ℉), it will increase the EC by 2-3%. This is why measuring the EC of the water you are working with is critical. 

Other factors are split into natural impacts and human impacts.

Natural impacts:

  • Evaporation
  • Precipitation

Human impacts:

  • Agricultural runoff
  • Road salts
  • Septic leachate

Testing Electrical Conductivity In Wastewater

Measuring the EC of water is a very easy and inexpensive way to identify how many ions are present in water. Conductivity measures the total concentration of ions in liquids, therefore, using a conductivity meter is perfect for monitoring the build-up of dissolved ionic solids in wastewater. 

Conductivity meters work by measuring the electrical current flow between electrons inside a conductivity probe. The probe reads the electrical current, providing a conductance value. 

Once the conductance value of the wastewater is determined, the correct treatment method can be applied. If wastewater is not treated, it can cause significant damage to the environment and also a potential health risk to both humans and other animals that rely on water sources. 

Untreated wastewater can also cause chronic ecosystem damage from oxygen depletion due to high organic matter and eutrophication from increases in the number of nutrients in the water. Water that contains excessive nutrients poses a health risk from water-borne pathogens. 

The easiest way to alter the EC in water is by increasing or decreasing the temperature of the water. However, most industries reduce the conductivity of water by removing the number of total dissolved solids (TDS) by an ion exchanger like flocculation, reverse osmosis (RO), or distillation. 

Summary

Electrical conductivity refers to the ability of water to conduct an electrical current in a solution over a certain distance, usually measured in Siemens (S) per distance (cm). 

In wastewater treatments, electrical conductivity determines if there are any variations or changes to the water quality. It can also be used to establish the number of chemicals needed to add to the water during sterilization and control the conductivity of the activated sludge process.

If you have questions regarding electrical conductivity or what conductivity probe will best suit your testing needs, do not hesitate to contact our world-class team at Atlas Scientific.

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