Resources
Glossary of Terms
Below is a list of common terms in wastewater treatment and pretreatment.
- Absorb Bag
- A bag that will prevent carryover of mechanically emulsified oil or oily coated solids.
- Chemical Emulsified Oil
- An oil droplet size of 5 microns or less. It usually is caused by the addition of surfactants. A chemical emulsion is stable and will not break down. Can be removed with chemical pre-treatment followed by an oil water separator or a DAF system with chemical pre-treatment.
- Clean Water Act
- A regulation of pollutant discharge in any US waters and the quality standards of surface waters. See regulations.
- Coagulation
- Floc formation as the result of adding chemicals. Coagulants destabilize suspended particles by reducing repulsive forces, allowing them to agglomerate.
- Coalesce
- To unite together to form a larger mass. Our oleophilic coalescing media unites oil droplets to form a larger oil mass. According to Stokes’ Law, the larger the oil droplet size, the faster it will rise to the surface, therefore separating the oil from water.
- Colloid
- Very small, insoluble, non-diffusible solid or liquid particles that remain in suspension in a surrounding liquid. Particles are usually 2 micron or less.
- Discharge Compliance
- Meeting the established limits of the NPDES permit. The regulations could differ from state to state and for different applications.
- Dispersed Oil
- Has a droplet size of 20 microns to 149 microns. Can be removed by a coalescing oil water separator.
- Dissolved Solids
- Any solid material that will dissolve in the liquid that is being filtered, such as sugar in water.
- Emulsion
- Any colloidal suspension of a liquid in another liquid that is normally immiscible.
- Flocculation
- The growing together of colloidal particles to form larger ones, which are called flocs and are easier to filter.
- Freeboard
- Clear space between the top of the liquid and the rim of the vessel.
- Free Oil
- Has a droplet size of 150 microns or greater. Can be removed by an API oil water separator.
- Hydrophilic
- Having a high affinity to water. Capable of uniting with water or dissolving in water.
- Hydrophobic
- Not capable of uniting or mixing with water.
- Hydrostatic Test
- A leak check that is performed by filling the vessel with water for a minimum of 4 hours or pressurizing the vessel with 5psi air to ensure the integrity of the vessel’s structure.
- Immiscible
- Incapable of being mixed.
- Laminar Flow
- Term synonymous with streamline flow and viscous flow. It is a flow in which the parallel layers are not disrupted. Laminar flow occurs at a low Reynolds number of less than 500.
- Mechanical Emulsified Oil
- An oil droplet size of 20 microns or less. It is usually caused by turbulence in the flow or by mixing in centrifugal pumps. Over time, a mechanical emulsion will break down. Can be removed by an oil water separator with a post treatment DAF system or clay filter.
- Media
- Different material that separates oil and solids from water or that absorbs oil from water. There are a wide variety of media types, such as coalescing plates, inclined plates, clay, carbon and mesh packs.
- Micron
- One millionth of a meter.
- NPDES Permits
- National Pollutant Discharge Elimination System (NPDES). A permit program that controls water pollution by regulating point sources that discharge pollutants into waters of the United States. See regulations.
- Oleophilic
- A material that attracts oil and not water. Our coalescing media has oleophilic characteristics that cause the oil droplets to grow in size, which speeds up to separation process.
- PPM
- A unit of concentration in parts per million
- PPB
- A unit of concentration in parts per billion
- pH Range
- An arbitrary scale of numbers from 0 to 14 indicating acidity or alkalinity of a solution. A neutral solution will have a pH close to 7, acidity is below 7 and alkalinity is above 7.
- Reynolds Number
- A dimensionless number. Re=(D*V*L)/M where D=density of the fluid; V=Velocity of the fluid; L= length between plates; M=Viscosity of the fluid. Need a Reynolds number of less than 500 for an oil water separator to perform properly.
- Settlable Solids
- Solid particles that have a greater specific gravity than water that will naturally settle out.
- Skimmers
- A device that removes the already separated oil from a separator.
- Soluble Oil
- A droplet size of 0.05 micron or less and transparent to the eye. This is also considered as a micro-emulsion.
- SPCC Rule
- Spill Prevention, Control and Countermeasure (SPCC). A plan for oil spill prevention, preparedness and response to prevent oil from getting into navigable waters and the shorelines. See regulations.
- Stokes’ Law
- A physical law that approximates the velocity of a particle falling under the action of gravity through a fluid. The particle will accelerate until the frictional drag of the fluid just balances the gravitational acceleration, after which it will continue to fall at a constant velocity known as the terminal or free-settling velocity.
- Surfactants
- Surface active agents, which are found in cleaning agents.
- Suspended Solids
- Naturally buoyant solid particles. They have a specific gravity close to water. Requires pre-treatment to prevent clogging of coalescing media.
- Suspension
- Any liquid containing undissolved solids.
- TDS
- Total Dissolved Solids
- Terminal Velocity
- Steady velocity achieved by a moving particle when gravitational forces are balanced by viscous forces.
- TSS
- Total Suspended Solids
- Turbulent Flow
- A flow regime in which the flow characteristics are governed mainly by the inertia of the liquid. Occurs at a high Reynolds number greater than 500.
- Viscosity
- The degree of fluidity. The property of the fluid’s molecular structure by which the resist flow.