AMIAD - Filtration Glossary
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Biological Oxygen Demand or Biochemical Oxygen Demand is a procedure, used in water quality management, for determining how fast biological organisms use up oxygen in a body of water.

The reverse flow of water, through a filter or filtration media, used for removing solids accumulated during the filtration process.

By-Pass valve
A valve used to control an alternative flow path.

Brackish water
Brackish water is water with a level of salinity between freshwater and seawater.
Brackish water contains between 0.5 and 30 grams of salt per liter.

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The accumulations of solids on a filter media that block it resist the water flow through the filter and increase the differential pressure.

Chemical Oxygen Demand - A water quality test that indirectly measures the amount of organic compounds in water (expressed in milligrams per liter).

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Organic and inorganic suspended solids collected on the filter element. Quantity of debris is usually expressed in PPM. Size of it usually expressed in micron.

Density of a body is the ratio of its mass to its volume - A measure of how tightly the matter within the body is packed together.

Depth filtration
Removing and retaining suspended solids by means of their interception and adhering to grains or fibers (filtration media).

Differential Pressure
Defined as the difference in pressure between upstream (inlet side of the filter) and downstream (outlet side of the filter).

The German Institute for Standardization (Deutsches Institut fur Normung e.V.); this institute establishes standards for testing and classifying filters.

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Effective Filtration Area
The Total Area of the Filter Medium which is exposed to flow and is usable for the filtration process.

The filtered liquid leaving the filter

The device that performs the actual process of filtration

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A device which removes particles from water by means of a physical barrier, chemical process and/or biological process

Filter area
The total area of a filter element, usually expressed in square inches or square centimeters

Filter Cake
The debris collected on the filter element, block it, resist the water flow through the filter and increase the differential pressure.

The process of removing solid particles from liquid or gas by forcing them through a porous medium

Filtration Degree
Size of pores in filtration medium (mm or microns)

Filtration Element
The active component of the filter, it determines the type of filter and the filtration level.

Filtration Velocity
Flow Rate / Cross Section Area [m/hr]
A flat metal ring with a hole in its center, through which a pipe passes, and with a number of smaller holes drilled circumferentially, destined for the connecting bolts.

Flow rate
Volume of water per unit of time

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Gallons per minute

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In-line filter
A filter assembly in which the inlet, outlet and filter element axes are in a straight line.

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Media filtration (depth filtration)
A thick layer of graded particles such as sand, gravel or other granular materials found inside filter housing and perform the filtration of water. The filtration rate depends on the effective size of the bedding and the water velocity through the filter.

The number of wires in a linear inch of a screen element

One millionth of a meter; known as a micrometer (Ám).
Particles size is usually described in microns.
Multi-layer screen
A combination of selected ratios of weave type screens creating a mechanical strength

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Open Area
The Pore Area of the filter medium; expressed often as a percentage of the total area.

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Particle Size Distribution
Defines which part of the TSS (Total Suspended Solids) is relevant to the desired filtration degree; Number Density or Volume Density.

Parts per million

Pounds per square inch - a pressure measurement unit

Removal of coarse particles or large debris prior to a finer filtration process

The preliminary treatment in the process of filtration (chemical of physical)

Measure of alkalinity or acidity

A channel or opening in a filter medium which allows passage of fluid

The ratio of pore volume to total volume of a filter medium expressed as a percentage.

Potable water
Water which is fit for consumption by humans and animals; it is also called drinking water. Water may be naturally potable or it may need to be treated in order to be safe.

The force over an area applied to an object in a direction perpendicular to the surface; usually expressed in pounds per square inch (PSI) or bar.

Pump (water pump)
A device which converts mechanical force and motion into hydraulic fluid power

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Raw Water
Intake water prior to any treatment or use

Any natural or artificial holding area used to store, regulate, or control water.

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Screen (filter screen)
Perforated cylindrical body made of metal or plastic wedge-wire or woven-wire elements housed in a plastic or steel body.

Screen filtration
Mechanical filtration using a screen to remove particles out of water

Secondary treatment
The removal of organic matter from waste water in a sewage treatment plant using aerobic biological processes

Solid particles in water that settles out over time

The residual semi-solid material left from the filtration process.

Suction-scanning (Also known as focused back-flush)
Suction force that is created by reversing flow through a small section of the screen element into a nozzle at the tip of a rotating scanning element.

Surface Water
All water naturally opened to the atmosphere (rivers, lakes, reservoirs, ponds, streams, impoundments, seas, estuaries, etc.)

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Tertiary Treatment
Advanced cleaning of wastewater that goes beyond the secondary or biological stage, removing nutrients such as phosphorus, nitrogen, and most BOD and suspended solids

TDS - Total Dissolved Solids

An expression for the substances contained in a liquid which are present in a molecular, ionized or micro-granular suspended form. The operational definition is that the solids must be small enough to pass through a two microns filter. The term is used as an indirect reflection of water salinity. The term is also known as total filterable residue.

The cloudiness or haziness of a fluid caused by suspended solids particles that are generally invisible to the naked eye, similar to smoke in air.
The measurement of turbidity is a key test of water quality and it is measured by the amount of Light transmission through a water sample.

Total Suspended Solids - TSS (in water filtration)
The total Concentration of Dirt Load in water; measured in milligrams per liter or PPM (parts per million).

Treatment Plant
A structure built to treat wastewater before discharging it into the environment.

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Vapor Pressure
The pressure at which water evaporates at a given temperature; the temperature at which the vapor pressure is equal to the atmospheric pressure is called the boiling point

The resistance of a fluid to flow, caused by internal friction between the fluid molecules and by intermolecular forces (M2/sec)

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Wastewater The spent or used water from a home, community, farm, or industry that contains dissolved or suspended matter.

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