Drinking water turbidity

Morris RD, Naumova EN, Levin R, Munasinghe RL (1996) Temporal variation in drinking water turbidity and diagnosed gastroenteritis in Milwaukee. Am J Public Health 86 237-239... 

Schwartz J, Levin R, Hodge K (1997) Drinking water turbidity and paediatric hospital use for gastrointestinal illness in Philadelphia. Epidemiology 8 615-620... 

STAS 6323 (1980) Drinking water. Turbidity determination Sadar MJ Understanding turbidity science, Booklet No. 11. Hach BIPM (1995) Comite Consultatif pour la Quantite de Matiere 51... 

Turbidity is the measure of suspended material in the water. Drinking water turbidity is measured by nephelometric turbidity units (NTU). The standard is based on a monthly average, not to exceed 1.0 mg L1. Also, the level must not exceed 5.0 mg L 1 on two consecutive days. 

The goal of filtration in the modem municipal treatment plant is a maximum of 0.1 ntu (nephelometric turbidity unit), which ensures a sparkling, clear water (8). Freedom from disease organisms is associated with freedom from turbidity, and complete freedom from taste and odor requites no less than such clarity. The National Interim Primary Drinking Water Regulations (NIPDWR) requite that the maximum contaminant level for turbidity at the point of entry into the distribution system be 1.0 ntu unless it can be shown that levels up to 5 ntu do not interfere with disinfection, interfere with the maintenance of a chlorine residual in the distribution system, nor interfere with bacteriological analyses. 

The increased requirements of drinking water in large cities becomes necessary to use sources of very soft water and because of its low salinity and pH are very aggressive and can bring on corrosion phenomena in the pipes of the pipeline, with the appearance of colour and turbidity... 

Lime is used in drinking water treatment to control pH, soften water, and control turbidity. Lime, in combination with sodium carbonate, is used to precipitate the major bivalent... 

Turbidity is a drinking water quality parameter and a groundwater well stabilization indicator. The clarity of water defines a physical property of turbidity. Suspended matter, such as clay and silt particles, organic matter, microscopic organisms, and colloids, causes natural waters to be turbid. Turbidity is measured optically as a lightscattering property of water. 

Rather than extracting water with solvent, the water sample is poured through a column or filter containing an absorbent resin. The organics will preferentially adsorb to the resin, which is subsequently desorbed with solvent. This technique has been used for PAHs, pesticides, and PCBs and has been well characterized for drinking water. Laboratories should take proper steps to evaluate the efficiency of this technique for effluent samples or turbid samples and may refer to EPA method 3535A or to guideline documents from SPE suppliers (e.g., Supelco bulletin 910). 

The maximum turbidity permitted in drinking water is 1 TU. In industrial waters, turbidity is measured in milligrams per liter of suspended solids. For example, in the case of mining sedimentation ponds, the law permits a monthly average concentration of 35 mg L-1, with a maximum of 70 mg L"1. High concentrations of suspended solids are known to inhibit aquatic life. Also, colloidal matter is known to carry various inorganic and organic pollutants. 

The City of Fort Benton, Montana, USA, obtains drinking water from the Missouri River. The then current filtration plant (20-30 yr old) was in need of upgrading. Rather than building a new filtration plant, the city built a new 0.088 mVs (2-MGD) treatment plant in 1987. Water is drawn through collectors installed 6-7.5 m (20-25 ft) below the riverbed, a system that allows the riverbed to naturally filter the raw water. Turbidities of water entering the treatment plant average 0.08 NTU. No Giardia cysts have been found in the water (55). 

A 50,000 GPD slow sand filtration water treatment plant supplies a community of 500 people with drinking water from a reservoir in a protected watershed. The raw water supply has the following characteristics (a) turbidity = 5-10 NTU (b) total estimated Giardia cyst level = less than 1 per 100 mL (c) pH = 6.5-7.5 (d) temperature = 5-15°C. 

Testing the potential of pipe materials to promote biofilm growth is needed because it may affect the taste, odor or turbidity of drinking water and may cause non compliance with microbiological water quality parameters and a risk to consumers health. Because EU Drinking Water Directive (98/83/EC) controls the water quality at the consumers tap instead of the point of supply, it is important to be assessed if the pipe material in drinking water supply systems release substances that may enhance or inhibit attached microbial growth. 

Drinking water quality is governed by physical, chemical, biological and bacteriological properties. Of the physical properties of drinking water, its appearance is evaluated (turbidity, colour), and also taste, odour and temperature [13-22]. 

As for its physical properties (temperature, colour, turbidity, odour) the criteria for service water are not so stringent as those for drinking water, however, it must not be repulsive, it must not contain toxic substances, and from the health aspects it must satisfy the standard for drinking water. 

How can you measure turbidity The National Primary Drinking Water Regulations set the standards for public water systems. Turbidity—a measure of the cloudiness of water that results from the suspension of solids in the water—is often associated contamination from viruses, parasites, and bacteria. Most of these colloid particles come from erosion, industrial and human waste, algae blooms from fertilizers, and decaying organic matter. 

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