Understanding Water Turbidity: Causes, Impacts, and Effective Solutions for Crystal Clear Water

Clearwater is a beautiful sight to behold, but what about when that crystal-clear appearance becomes murky and cloudy? Water turbidity becomes crucial in this context, as it can greatly affect various aspects of our everyday existence, such as the quality of our drinking water and the well-being of aquatic ecosystems.

Today, we explore what water turbidity is, its causes, and its effects, as well as how we can measure and manage it.

Figure 1 Turbidity.

What is Water Turbidity?

The term water turbidity indicates the degree to which water appears hazy or cloudy. This is often an indication that the water harbors suspended elements. These particles can include organic and inorganic matter such as clay, silt, plankton, and other debris that make the water appear opaque or murky. Turbidity is typically measured in NTU (Nephelometric Turbidity Units) or FTU (Formazin Turbidity Units), and is an important indicator of water quality, as high turbidity levels can affect aquatic life, alter water temperature, and reduce the effectiveness of water treatment processes.

Causes of Water Turbidity

Multiple factors contribute to water turbidity, including:

● Natural Erosion

Natural erosion is a common cause of water turbidity. As water moves over land, it can pick up soil particles, minerals, and other debris, which can then become suspended in the water.

● Algae Blooms

Algae blooms are another common cause of water turbidity. When water bodies, such as lakes or ponds, experience excess nutrients, such as nitrogen and phosphorus, algae can proliferate and create a cloudy, greenish-brown appearance.

● Industrial Runoff

Industrial runoff can also contribute to water turbidity. Industrial activities, such as mining or construction, can result in sediment or other materials entering nearby waterways and causing turbidity.

Figure 2 Industrial runoff.

● Urban Runoff

Urban runoff, which includes stormwater runoff from streets and buildings, can also contribute to water turbidity. As water flows over impervious surfaces, such as concrete or asphalt, it can pick constituents, which can alter its color.

Turbidity Measurement

● Secchi Disk

A Secchi disk comprises black and white quadrants in a circular pattern and is submerged in the water until it is no longer visible. The point at which it vanishes is recorded and utilized to estimate the water’s turbidity.

● Optical Backscatter

Optical backscatter computes water turbidity by establishing the quantity of light reflected backward by the harbored particulates. A backscatter sensor is used to measure the scattered light, and the amount of scattered light is used to determine the turbidity of the water.

Optimal Clarity Levels for Safe Drinking Water

The vast majority of people in every region of the world agree on one thing: the turbidity of drinking water shouldn’t be higher than one NTU. According to guidelines set by the World Health Organization (WHO), the turbidity of drinking water should not surpass 5 NTU. This is supported by the Environmental Protection Agency (EPA) of the United States of America, which mandates that water that is intended for public consumption must not exceed one NTU in terms of its level of turbidity.

The Negative Effects of Excessive Water Turbidity

To guarantee the safety and appropriateness of water for its intended purpose, it is crucial to oversee and manage its turbidity levels.

  • Aesthetic issues: High turbidity can make the water look cloudy or murky, which may be unappealing to drink or use for other purposes.
  • Impeded Disinfection: The efficacy of disinfection can be diminished due to high turbidity, as suspended particles can act as a barrier between pathogens and the disinfectant, hindering processes such as chlorination and UV sterilization.
  • Reduced light penetration: High turbidity can reduce the amount of light that penetrates the water, which can negatively affect aquatic life that depends on light for photosynthesis.
  • Health risks: Some suspended particles in high turbidity water can carry harmful bacteria or viruses, which can pose health risks if consumed.

How to Shrink Water Turbidity Levels?

● Sedimentation

Sedimentation lets the unclean and unclear water stand motionless in a container to enable the suspended particles to settle at the bottom. The settled-down particles are then left behind, while the clear water is drained out from the top of the tank. The sedimentation process is affected by factors such as particle size and weight, water temperature, and tank depth, all of which can influence the rate at which sedimentation occurs.

Figure 3 Media filter.

● Media Filtration

Media filtration utilizes a porous material, such as activated carbon, gravel, anthracite, or sand to clean water. This involves passing water through the filter media, which results in suspended particles getting trapped, yielding clearer water. The efficiency of media filtration is dependent on several factors, including the quality and size of the filter media, the flow rate, and the concentration of particles in the water.

Ultrafiltration

The use of a perforated membrane in ultrafiltration allows the eradication of particles as small as 0.01 microns, making it a highly advanced filtration method. By serving as a barrier, the membrane permits the passage of water while trapping suspended particles and other turbidity-causing elements. This has made ultrafiltration systems a prevalent technique for industrial and municipal water treatment purposes.

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