Water Treatment Terms………….The Letter T

TASTE THRESHOLD: The minimum concentration of a chemical or biological substance which can just be tasted.

TCE: trichloroethene

TDS: total dissolved solids.

TEFLON: The trade name of a high temperature industrial plastic material used in cooking, finishes, bearings, lubricating, plumbing sealants, and a practically inert coating on metal and glass surfaces.

TERTIARY WASTEWATER TREATMENT (ADVANCED): Biological or chemical polishing of wastewater to remove organics, solids and nutrients. Tertiary wastewater effluent limits are generally 10 mg/1 BOD5 and 10 mg/1 TSS.

TFC: Thin film composite.

TH: Total hardness.

THIN FILM COMPOSITE MEMBRANE (TFC): A class of reverse osmosis membranes made with polyamide-based polymer and fabricated with different materials in the separation and support layers.

THIOBACILLUS: A small single celled sulphur bacterium which can create hydrogen sulphide gas and the resulting “rotten-egg” odour in water supplies.

THMs: Trihalomethanes.

TITRATABLE ALKALINITY:  When certain anions, such as carbonate (CO3=), are dissolved in water, they bind hydrogen ions (H+) and thus shift the water equilibrium (see definition of pH) to produce free hydroxyl ions (OH-).  This excess concentration of OH- is termed alkalinity.  Titratable alkalinity can be measured by determining the amount of H+ (in mEq or mmol) which must be added to water to restore the pH to 7.0, the condition of neutrality where [H+] = [OH-].

TOC: Total organic carbon.

TORTUOUS PATH: Water flow through channels which are constricted and marked by repeated twists, bends and winding turns.

TOTAL CHLORINE: The total concentration of the chlorine in a water, including the combined available chlorine and the free available chlorine.

TOTAL DISSOLVED SOLIDS (TDS): The total weight of the solids that are dissolved in the water, given in ppm per unit volume of water. TDS is determined by filtering a given volume of water (usually through a 0.45 micron filter), evaporating it at a defined temperature (usually 103 – 105 degrees Celsius) and then weighing the residue.

TOTAL HARDNESS (TH): The total of the amounts of divalent metallic cations, principally calcium hardness and magnesium hardness, expressed in terms of calcium carbonate equivalent.

TOTAL MATTER: The sum of all suspended and dissolved matter in a water sample.

TOTAL ORGANIC CARBON:  Organic compounds dissolved in water are characterized by their carbon content.  Total organic carbon is the mass of carbon present in a water sample, excluding the carbon present as CO2 and/or carbonates.  The values are determined by catalytically oxidizing (burning) all dissolved carbon (after CO2/CO3= removal by acidification) to CO2.  The resulting CO2 may be measured directly by infra-red absorption, or it may be reduced in a furnace with hydrogen to form methane, which is measured by flame ionization detectors.

TOTAL SOLIDS (TS): The weight of all organic and inorganic solids, both dissolved and suspended, per unit volume of water.

TOTAL SUSPENDED SOLIDS (TSS): Total suspended solids in wastewater.

TOXIC: Poisonous (to human beings); capable of producing disease or otherwise harmful to human health when taken into the body.

TRACE ELEMENT: An element essential to plant and/or animal nutrition in trace concentration of 1% of less.

TRACE SUBSTANCE (or trace): A substance which is found during water analysis in a small concentration, high enough to be detected , but to low to be quantified accurately by standard testing methods.

TRANSPIRATION: The process of plants giving off watery vapor from their leaves and other surfaces.

TRICHLOROETHENE (TCE): A toxic volatile organic compound often found as a solvent.

TRIHALOMETHANES (THMs): A group of organic chemicals, suspected of being carcinogenic, which are formed in water when chlorine being used as a disinfectant reacts with natural organic matter such as humic acids from decayed vegetation.

TURBIDITY:  a measure of the presence of colloidal matter in the water that remains suspended.  Suspended matter in a water sample, such as clay, silt, or finely divided organic and/or inorganic matter will scatter the light from an incident light beam.  The extent of scattering is expressed in Jackson or Nephelometric turbidity units (JTU and NTU, respectively).