GLOSSARY OF TERMS: Filters & Membranes

ALGAE: Aquatic photosynthetic organisms that can range from single-cell forms to giant kelp. Highly deformable, algae can be a significant challenge to many filtration systems.

BACK FLUSH: The reverse flow of water through a filtration system, used to dislodge trapped particles.

BRACKISH: A level of salinity between fresh water and seawater – generally 0.5 to 30 grams of salt per liter.

DELTA: Change. A specific "Delta-P," or a pressure differential across a filter surface, is the trigger for self-cleaning in many sophisticated filtration systems.

DESAL: Short for desalination, the removal of salts from water.

EFFLUENT: Filtered liquid leaving the filter.

ELEMENT: The device that performs the filtration.

FILTER CAKE: Debris collected on the surface of the filter.

FILTRATION DEGREE: The size of the pores in the filtration medium.

FLUX: The rate of water flow per unit of membrane filtration area.

FOULANT: Material that obstructs, such as sediment or biological material that blinds a filter or intake.

GPM: Gallons per minute.

MICRON: One-millionth of a meter, or micrometer.

POTABLE: Suitable for drinking.

PRESSURE: The force of an object applied in a direction perpendicular to its surface. A key metric in filtration systems.


RECOVERY: The amount of feed flow that is converted into filtrate flow by a membrane filtration system.

SEDIMENT: Solid particles of organic or inorganic material, generally from weathered rock.

TDS: Total dissolved solids. These solids are in molecular, ionized or microgranular form and can pass through a two-micron filter.

TERTIARY: Treatment of water to remove nutrients such as phosphorus and nitrogen.


TSS: Total suspended solids. Generally solids that can be captured by a filter with a filtration degree.

TURBIDITY: The cloudiness or haziness of a liquid caused by particles invisible to the naked eye.

WEAVEWIRE: A screen constructed of interlaced wire, yielding uniformly square pores.

The terms and definitions for this glossary were contributed by Jim Lauria, vice president of sales & marketing for Amiad Filtration Systems (www.amiadusa.com), a provider filtration solutions for industrial, municipal, and agricultural use. Mr. Lauria can be reached at [email protected].