Glossary of Terms - B
A B C D E F G H I J K L M N O P Q R S T U V W Z
backflow - Flow of water in a pipe or line in a direction opposite to normal flow. Often associated with back siphonage or the flow of possibly contaminated water into a potable water system.
back-flow preventer - A device or system installed in a water line to stop back-flow from a non potable source. (See air gap.)
backwash - The process in which beds of filter or ion exchange media are subjected to flow opposite to the service flow direction to thoroughly expand the bed to flush particulate matter collected during the service run.
bacteria - Single cell organisms which lack well-defined nuclear membranes and other specialized functional parts and reproduce by cell division or spores.
bacteriostatic - Having the ability to inhibit the growth of bacteria without destroying the bacteria. For example: silver-impregnated activated carbon will reduce bacterial colonization in a bed but not eliminate it.
base - A alkali which releases hydroxyl ions when dissolved in water. (See alkali.)
base exchange - See cation exchange.
batch - A quantity of material treated or produced as a unit.
batch treatment - A method in which a fixed quantity of water is processed through a single treatment device in a single vessel.
bay salt - A relatively coarse salt made from seawater.
bed - The mass or volume of ion exchange resin or other media through which water is passes in the process of water treatment.
bed depth - The height of the ion exchange resin or other media (excluding support material) in a vessel, usually expressed in centimeters or inches.
bed expansion - The effect produced during backwashing when the resin or other medium becomes separated and rises in the tank or column. Usually expressed as the percent of increase of bed depth.
bicarbonate alkalinity - The alkalinity of a water due to the presence of bicarbonate ions (HCO3-).
biochemical oxygen demand (BOD) - The amount of oxygen (measured in mg/L) required the oxidation of organic matter by biological action under specific standard test conditions. Widely used to measure the amount of organic pollution in streams and waste water.
biodegradable - Subject to degradation (breakdown) to simpler substances by biological action, such as the bacterial breakdown of detergents, sewage wastes and other organic matter.
BIRM - The trade name for manganese dioxide-coated volcanic aluminum silicate (pumicite) used as an oxidizing-catalyst filter for iron and manganese reduction.
bleach - A strong oxidizing agent and disinfectant formulated to break down organic matter and destroy biological organisms. Commonly refers to a 5.25 percent nominal solution of sodium hypochlorite (household bleach) which is equivalent to three to five percent available free chlorine (strength varies by shelf life).
blowdown - The process which removes oxidized contaminants or particulate waste from a vessel in order to maintain the solids-to-water concentration ratio within specified limits.
BOD - Abbreviation for "Biochemical Oxygen Demand".
bonnet - The cover on a gate valve.
bored well - A shallow (10 to 100 feet or 3 to 30 meters) large-diameter well (8 to 36 inches or 20 to 90 cm) constructed by hand-operated or power-driven augers.
brackish water - Water containing dissolved solids in the range >1,000ppm (parts per million) to <15,000ppm.
breakpoint chlorination - A chlorination procedure in which chlorine is added until the chlorine demand is satisfied and a chlorine residual occurs. The breakpoint is reached when free chlorine residual is achieved. Further additions of chlorine produce a chlorine residual proportional to the amount added.
breakthrough - The appearance in the effluent from a water conditioner of the material being removed by the conditioner, such as hardness in the effluent of a softener, or turbidity in the effluent of a mechanical filter; an indication that regeneration, backwashing, or other treatment is necessary for further service.
bridging - 1. Bridging occurs in water softening when salt sticks together to form one large solid mass of pellets, or by the salt caking in a dry-salt brine tank which causes failure of the liquid or brine beneath the dry salt to become saturated. The result of bridging is insufficient salt in the regenerant solution to properly regenerate the cation resin. 2. The ability of particles to form a crust like film over void spaces within a filter medium or membrane. (See mushing)
brine - A strong solution of salt(s), usually sodium chloride and other salts too, with total dissolved solids concentrations in the range of 40,000 to 300,000 or more mg/L. Potassium or sodium chloride brine is used in the regeneration stage of ion exchange water treatment equipment.
buffer - A chemical substance which stabilizes pH values in solutions.
builder - A chemical incorporated in a detergent formulation to produce a desired alkalinity level and improve the ability to suspend soil. The alkaline phosphates are widely used for this purpose.
bypass - A connection or a valve system that allows untreated water to flow through a water system while a water treatment unit is being regenerated, backwashed or serviced; also applied to a special water line installed to provide untreated water to a particular tap, such as a sill cock.