PARTICLE FILTRATION: Filtration of particles in the size range of 2 microns or larger in diameter. Particle filtration is typically handled by cartridge filters and media filters.
PARTICLE SIZE: As used in water industry standards, this term refers to the size expressed in microns, of a particle suspended in water as determined by the smallest dimension.
parts per billion (ppb): A measure proportion by weight which is equivalent to one unit weight of solute (dissolved substance) per billion unit weights of the solution.
PARTS PER MILLION (ppm): A measure of proportion by weight which is equivalent to one unit of weight of solute (dissolved substance) per million weights of solution. Since one litre of water weighs one million milligrams, one ppm is equal to one milligram per litre (mg/L). PPM is the preferred unit of measure in water or wastewater analysis.
PATHOGENIC: Capable of causing disease.
PATHOGENS: Any disease producing organism.
PERCENT RECOVERY: The percentage of the feed water which becomes product water. Determined by the number of gallons (or litres) of product water divided by the total gallons (or liters) of feed water and multiplied by100. The percent recovery is called recovery rate in reverse osmosis and ultra filtration.
PERCENT REJECTION: (reverse osmosis/ultra filtration) The percentage of TDS in the feed water that is prevented from passing the membrane with the permeate. The formula used is: the difference obtained from the TDS in permeate divided by TDS in feed water; then multiply the answer obtained by 100 to obtain a percentage.
PERMEATE: That portion of the feed water which passes through the membrane to become product water.
pH: Water (H2O) can dissociate into two ions: hydrogen (H+) and hydroxyl (OH-). These ions can also be added to water in combination with other oppositely charged ions. Thus, a solution of hydrochloric acid added to the water provides both H+ and the chloride anion, Cl-. The concentration of H+ in the water is a measure of water’s acidity. To simplify quantitation of H+ differences, where numbers with a wide range of exponents are encountered, scientists devised a logarithmic scale called pH. The pH values range from 1 to 14. A pH value of 7 is considered neutral. Lower values of pH indicate acidic conditions and higher pH values indicate alkaline conditions. Because pH is a logarithmic scale, and increase of 1 pH unit corresponds to a ten-fold change in acidity.
PHOSPHATE: A salt of phosphoric acid. In the water treatment industry, poly phosphates are used a sequestering agents to control iron and hardness, and as a coating agent to control corrosion by formation of a thin passivating film on metal surfaces.
PHOSPHOROUS (P): This nutrient, which is present in wastewater, acts as a fertilizer for algae in surface waters.
PHS: The pH of water at which it is theoretically in equilibrium with calcium carbonate, i.e., saturated.
POE: Point of entry.
POINT OF ENTRY (POE) treatment: Full service water treatment at the inlet to an entire building or facility (outside faucets may be excepted from treatment).
POINT OF USE (POU) treatment: Water treatment at a single outlet or limited number of water outlets in a building, but for less than the whole building or facility. POU treatment is often used to treat water for drinking and cooking only.
POLISHING FILTER: A filter installed for use after the primary water treatment stage to remove any trace of undesirable matter or to polish the water.
POLLUTANT: A contaminant existing at a concentration high enough to endangered the environment or the public health or to be otherwise objectionable.
POLYELECTROLYTE: A high molecular weight water soluble polymer containing chemical groups capable of undergoing electrolytic dissociation to give highly charged ions. Polyelectrolytes often have a synergistic effect when used with coagulating agents.
POLYPHOSPHATE: A form of phosphate polymer consisting of a series of condensed phosphoric acids containing more than one atom of phosphorous. Polyphosphate is used as a sequestering agent to control iron and hardness, and as a coating agent that forms a thin passivating film on metal surfaces to control scale.
POROSITY: A measure of the volume of pores in a material. Porosity is calculated as a ration of the interstices of material (e.g. the volume of spaces between the media particles in a filter bed) to the volume of its mass, and is expressed as a percentage.
POROUS: Full of pores through which water, light etc may pass.
POTABLE WATER (drinking water): A water supply which meets U.S. EPA and/or state water quality standards and is considered safe and fit for human consumption.
POTASSIUM CHLORIDE (KCl): A colourless potassium salt which can be used as a regenerate in cation exchange water softeners.
POTENTIOMETRIC TITRATION: A titration in which a rapid change in pH is used to measure the end point.
POU: Point of use.
POUNDS PER SQUARE INCH (psi): unit of measure for expressing pressure.
ppb: Parts per billion.
ppm: Parts per million.
ppt: Parts per trillion.
PRESSURE DIFFERENTIAL: The difference in the pressure between two points is a water system. The difference may be due to the difference in elevation and/or to pressure drop resulting from water flow.
PRESSURE DROP: A decrease in the water pressure (in psi) which occurs as the water flows. The difference between the inlet and outlet water pressure during water flow through a water treatment device.
PRESSURE, EFFECT ON OUTPUT: RO output varies directly with Net Pressure.
PRESSURE, NET APPLIED: The average of the pressure in the feedwater and the pressure in the concentrate upstream from the pressure control valve.
PRETREATMENT: Any water treatment step performed prior to the primary treatment process, such as filtration prior to deionization.
PRIMARY WASTEWATER TREATMENT: Removal of sand, grit, and larger solids from wastewater by screens, settling tanks and/or skimming devices.
PROCESS WATER: Water used in a manufacturing or treatment process or in the actual product manufacture.
PRODUCT WATER: Water that has been through the total treatment process and meets the quality standards required for the use to which the water will be used.
PRODUCTION RATE: The amount (gallons or litres) of product water the system produces per minute or (especially for reverse osmosis) per 24 hour period.
PROTOTYPE: an original water treatment equipment unit on which a specific equipment line is modelled.
PROTOZOA: Microscopic, usually single celled microorganisms which live in water and are relatively larger in comparison to other microbes. Protozoa are higher on the food chain than the bacteria that they eat. Many protozoa are parasitic.
psi: Pounds per square inch.
PURE WATER: This term has no real meaning unless the word “pure” is defined by some standard such as pharmaceutical grade water.
PURIFIED WATER: A USP grade water produced from water meeting U.S. EPA standards for potable drinking water which has microbiological content under control and is free from foreign substances.
PUTREFACTION: The decomposition (rotting) of organic matter caused by microbes and oxidation.
PYROGENS: Substances (often of unknown origin) that produce fever when introduced into the human body. Being chemically and physically stable, pyrogens are not necessarily destroyed by conditions that kill bacteria.
QUALIFICATION TEST: Test and verifications performed to validate water treatment equipment conformance to a specific standard.
QUARTZ SLEEVE or quartz jacket: A clear, pure fused quartz tube used to protect the high intensity ultraviolet lamps in ultraviolet systems. It usually retards less than 10% of the ultraviolet radiation dose.