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What is Turbidity?

 

  • Turbidity is the visual indication of particulates in suspension that interfere with light transmission through water. The particles absorb and diffuse the light.

  • Turbidity levels can range from slight, measurable by instrumentation, to much greater levels that cause visible cloudiness and sometimes color; approximately 4 ntu is barely detectable visually.

  • The particulates can be of organic or inorganic composition.

  • Turbidity can also be caused by a release of dissolved air or other gases that can occur when pressure is released at the tap. This is temporary and the water will quickly clarify.

  • Excess turbidity can have both health and aesthetic implications

 

 

 

Where Does Turbidity Come From?
 

  • Turbidity in groundwater is often from mineral particulates including reduced iron, clay particles or calcium carbonate precipitation.

  • Turbidity in surface water will more likely be from suspended sediments or organic particulates and these frequently have attached microorganisms.

  • In distributed water, turbidity can occur from sediments and biofilm releases or from backflow of unsafe water or cross connections.

  • Surface water turbidity increases during rainfall and runoff and that intensifies the load on treatment processes.

 

Health Issues:

  • Turbidity is a frequent indicator of microbial contamination because of the likelihood of microorganisms bound to suspended particulates.

  • For surface waters it is a likely indicator of inadequate water treatment.

  • Organic turbidity increases disinfectant demand and reduces the efficacy of disinfection processes.

  • Microorganisms bound to particulates are more protected from the disinfectant, which is another reason whyfiltration is important.

 

Water Treatment:

  • Filtration technologies are the standard methods for reducing turbidity.

  • Conventional coagulation, flocculation and granular filtration as well as direct filtration are effective.

  • Membrane technologies, including microfiltration, ultrafiltration, nanofiltration as well as Reverse Osmosis, are effective.

 
 
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