Turbidity

Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air.

[2] Some industries such as quarrying, mining and coal recovery can generate very high levels of turbidity from colloidal rock particles.

The suspended solids interfere with water disinfection with chlorine because the particles act as shields for viruses and bacteria.

[citation needed] In water bodies such as lakes, rivers and reservoirs, high turbidity levels can reduce the amount of light reaching lower depths, which can inhibit growth of submerged aquatic plants and consequently affect species which are dependent on them, such as fish and shellfish.

High turbidity levels can also affect the ability of fish gills to absorb dissolved oxygen.

[4][5] For many mangrove areas, high turbidity is needed in order to support certain species, such as to protect juvenile fish from predators.

Open source hardware has been developed following the ISO 7027 method to measure turbidity reliably using an Arduino microcontroller and inexpensive LEDs.

Modern instruments do not use candles, but this approach of attenuation of a light beam through a column of water should be calibrated and reported in JTUs.

[7] The propensity of particles to scatter a light beam focused on them is now considered a more meaningful measure of turbidity in water.

Turbidity measured this way uses an instrument called a nephelometer with the detector set up to the side of the light beam.

Depending on the application, flocculants may be dosed into the water stream to increase the effectiveness of the settling or filtration process.

[21][22] Potable water treatment and municipal wastewater plants often remove turbidity with a combination of settling tanks, granular media filtration, and clarifiers.

In-situ treatment of turbidity involves the addition of a reagent, generally a flocculant, evenly dispensed over the surface of the body of water.