How to measure the turbidity of drinking water?

Turbidity is an index that reflects the physical properties of source water and drinking water. The turbidity of source water is due to the optical scattering or absorption behavior of suspended matter or colloidal matter, or both. The turbidity of drinking water and its source water was determined by scattering method with formazin as standard. The minimum detectable turbidity is 0.5 nephelometric units (NTU). The principle is to compare the scattered light intensity of the formalazine standard suspension with the scattered light intensity of the water sample under the same conditions. The greater the intensity of the scattered light, the higher the turbidity. Reagents required for the determination of turbidity in drinking water testing: 1) Pure water: take distilled water and filter it through a 0.2 μm membrane filter. 2) Hydrazine sulfate solution (10 g/L): Weigh 1.000 g of hydrazine sulfate, dissolve it in pure water and dilute to volume in a 100 mL volumetric flask. Note: Hydrazine sulfate is carcinogenic and toxic, avoid inhalation, ingestion and skin contact! 3) Cyclohexamethylenetetramine solution (100 g/D: weigh 10.00 g of cyclohexamethylenetetramine and dissolve in pure water, Dilute to volume in a 100mL volumetric flask. 4) Formazin standard suspension: respectively draw 5.00mL of sulfuric acid solution and 5.00mL of cyclohexamethylenetetramine solution into a 100mL volumetric flask, mix well, and store at 22°C After standing at -28°C for 24 h, add pure water to the mark and mix well. This standard suspension has a turbidity of 400 NTU and can be used for about one month. 5) Formazin turbidity standard solution: Dilute the formazin turbidity standard suspension 10 times with pure water. The turbidity of this suspension is 40 NTU, and it should be diluted appropriately when used. Turbidity measurement and analysis steps for drinking water testing: operate according to the instrument instruction manual. When the turbidity exceeds 40 NTU, it can be diluted with pure water and then measured. Calculation of turbidity measurement for drinking water testing: Calculate the result based on the turbidity reading displayed by the drinking water testing instrument multiplied by the dilution factor.