That pressure of a gas in a liquid, which is in equilibrium with the solution. In a mixture of gases, the partial pressure of any one gas is the total pressure times the fraction of the gas in the mixture (by volume or number of molecules).

The sizes of a particle, determined by the smallest dimension, for instance a diameter. It is usually expressed in micron measurements.

The mass of particulates per unit volume of water.

Expressed as ppb; a unit of concentration equivalent to the µg/l.

Expressed as ppm; a measure of concentration. One ppm is one unit weight of solute per million unit weights of solution. In water analysis the ppm is equivalent to mg/l.

The elimination of microorganisms by heat applies for a certain period of time.

Disease-producing microorganisms.

The amount of a substance that is dissolved in a solution compared to the amount that could be dissolved in it.

Water that passes through rocks or soil under the force of gravity.

Arrangement of elements in order of increasing atomic numbers, created by a scientist called Mendelejef.

The ability of a medium to pass a fluid under pressure.

Refers to the length of time a compound stays in the environment, once introduced.

The value that determines if a substance is acid, neutral or basic, calculated from the number of hydrogen ions present. It is measured on a scale from 0 to 14, on which 7 means the substance is neutral. pH values below 7 indicate that a substance is acidic and pH values above 7 indicate that it is basic.

A state of matter. This can be solid, liquid or gaseous.

The process of conversion of water and carbon dioxide to carbohydrates. It takes place in the presence of chlorophyll and is activated by sunlight. During the process oxygen is released. Only plants and a limited number of microorganisms can perform photosynthesis.

Processes generally used in wastewater treatment facilities. Physical processes are for instance filtration. Chemical treatment can be coagulation, chlorination, or ozon treatment.

Breaking down of rock into bits and pieces by exposure to temperature and changes and the physical action of moving ice and water, growing roots, and human activities such as farming and construction.

Free-floating, mostly microscopic aquatic plants.

The testing of a cleanup technology under actual site conditions in a laboratory in order to identify potential problems before implementation.

Point-Of-Entry treatment. Total water treatment at the inlet to an entire building or facility.

An opening in a membrane or medium that allows water to pass through.

A stationary location from which pollutants are discharged. It is a single identifiable source of pollution, such as a pipeline or a factory.

A substance that carries a positive or negative charge, for instance water.

A contaminant at a concentration high enough to endanger the life of organisms.

Persistent Organic Pollutants, complex compounds that are very persistent and difficultly biologically degradable.

Water that is safe for drinking and cooking.

The ability of one chemical to increase the effect of another chemical.

The surface to which water in an aquifer can rise by hydrostatic pressure.

Point-Of-Use treatment. Water treatment at a limited number of outlets in a building, for less than the whole building.

An insoluble reaction product in an aqueous chemical reaction.

The altering of dissolved compounds to insoluble or badly soluble compounds, in order to be able to remove the compounds by means of filtration.

A system of pipes in which water, wastewater, or other liquid is pumped to a higher elevation.

Processes used to reduce or eliminate wastewater pollutants from before they are discharged.

The removal of suspended, floating and precipitated solids from untreated wastewater.

Water that serves in any level of the manufacturing process of certain products.

Water that has passed through a water treatment plant and is ready to be delivered to consumers.

Positively charged building blocks of an atom that are centered in the nucleus.

Large microorganisms, which consume bacteria.

A system that provides piped water for human consumption to at least 15 service connections or regularly serves 25 individuals.

Biological decomposition of organic matter; associated with anaerobic conditions.

Substance that is produces by bacteria and it fairly stable. It causes fever in mammals.