Glossary of Water Treatment Terms & Definitions - T

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TCE (Trichloroethylene)

A toxic volatile organic chemical typically used as an industrial solvent.

TDS

The abbreviation for "total dissolved solids".

Tannin

A naturally occurring substance in wood, grapeskins, seeds and stems. Is primarily responsible for the basic "bitter" component in wines. Acts as a natural preservative, helping the development and, in the right proportion, balance of the wine. Considered a pollutant when present in excess.

Tertiary Treatment

The third stage in the treatment of sewage that in a high degree of conditioning following the reduction of pollutants accomplished by the primary and secondary stages of treatment.

Thin-film Composite Membrane (TFC)

Reverse osmosis membrane produced with polyamide-based polymer. It is resistant to bacteria and can withstand a wide pH range. However, it cannot tolerate chlorine.

Throughput Volume

The amount of solution passed through an exchange bed before exhaustion of the resin is reached.

Total Acidity

The total of all forms of acidity, including mineral acidity, carbon dioxide, and acid salts. Total acidity is usually determined by titration with a standard base solution to the phenolphthalein endpoint (pH 8.3).

Total Alkalinity

The alkalinity of a water as determined by titration with standard acid solution to the methyl orange endpoint (pH approximately 4.5); sometimes abbreviated as "M alkalinity". Total alkalinity includes many alkalinity components, such as hydroxides, carbonates, and bicarbonates.

Total Chlorine

The total amount of chlorine is a solution, which includes the combined chlorine as well as the free available chlorine.

Total Dissolved Solids

The weight of solids per unit volume of water which are in true solution, usually determined by the evaporation of a measured volume of filtered water, and determination of the residue weight. TDS is expressed as ppm per unit volume of water. An electrical conductivity test provides only an estimate of the TDS since non-conductive substances cannot be measured by electrical means.

Total Hardness

The sum of all hardness components in a water, expressed as their equivalent concentration of calcium carbonate. Primarily due to calcium and magnesium in solution, but may include small amounts of metals such as iron which can act like calcium and magnesium in certain reactions. These minerals are scale forming, affect taste and color of certain foods and react with soap to form insoluble soap curds.

Total Organic Carbon

The measurement of carbon dioxide produced from organics when a water sample is atomized into a combustion chamber. The amount of carbon covalently bound in organic compounds in a water sample.

Total Solids

The weight of all solids, dissolved and suspended, organic and inorganic, per unit volume of water; usually determined by the evaporation of a measured volume of water at 105 degrees Celsius in a pre-weighed dish.

Trihalomethanes (THM's)

A group of organic chemicals to known to be carcinogenic in more than trace amounts which are produced from chlorination. They reduce the germicidal activity of chlorine in alkaline water.

Turbidity

A measure of the amount of finely divided suspended matter in water, which causes the scattering and adsorption of light rays. Turbidity is usually reported in arbitrary nephalometric turbidity units (NTU) determined by measurements of light scattering. NTU should not exceed 0.5 in potable water. Turbidity can protect bacteria from sterilization.