Decentralized Wastewater Glossary

Measurement of the suction produced in a vacuum system relative to ambient atmospheric pressure.

pump that removes air from a cargo tank to create a vacuum (or partial vacuum); may also be operated in reverse mode to produce pressure.

Process of allowing air entry into a component to relieve a vacuum condition.

Valve that limits the vacuum level in a vacuum cargo tank (or suction line) to a preset level by allowing air to enter, thereby assuring that the operating vacuum level is not exceeded.

Sewage collection system using a basin or tank for collection of sewage or effluent with subsequent conveyance by vacuum to downstream system components; typical maintenace access includes cleanouts located in the piping network.

Motorized vehicle equipped with a vacuum system consisting of vacuum pump, cargo tank and associated equipment.

Aerated, unsaturated region of soil above the zone of saturation.

One of the three variables of color, described as the degree of lightness or darkness of the color in relation to a neutral gray scale; on a neutral gray scale, value extends from pure black to pure white; see also Munsell Color System; hue; and chroma.

Mechanical device used to close off, regulate, or divert the flow of fluid.

Housing that encloses an operating component or device and extends to the ground surface, allowing access for component inspection, operation, etc.

Controlling or modulating flow through a system by manually or automatically opening or closing a valve to various degrees; in a pump system, changing the valve to various positions between full open and full closed regulates the amount of flow delivered and the operating pressure or head.

Waterless toilet mounted on a vented holding tank designed to store non-water-carried human waste prior to offsite treatment.

Device that allows the active or passive entrance or exit of gases from a component.

Vertical distance between the infiltrative surface and a limiting condition, such as highest groundwater level, bedrock, etc.

Trench installed with 4 or more feet of distribution media below the lateral.

Mechanical device such as a jumping jack that consolidates loose soil material.

Oscillating plow shank used for installing subsurface drip tubing and utility lines.

An obligate parasite dependent on a host cell for its metabolic and reproductive needs; a constituent of concern in biological wastewater treatment systems.

Capable of evaporating at relatively low temperatures.

Measure of those solids that can be volatilized and burned off when the total dissolved solids are ignited at 500 +/- 50°C; typically expressed in mg/L.

Class of organic compounds that readily evaporates; includes liquids and solids at natural environmental temperature; examples include solvents, adhesives and fuels).

Weight loss on ignition of solids, not distinguishing between inorganic and organic matter, and including loss due to decomposition or volatilization of some mineral salts at 500 +/- 50°C.

Measure of those solids that can be volatilized and burned off when the total suspended solids are ignited at 500 +/- 50°C; typically expressed in mg/L.

The electric potential difference between two points, which causes the movement of electric charge.

1. The amount of space that a liquid or solid object occupies, typically measured in cubic units; 2. The space occupied within the boundaries of an object (such as a tank, chamber or compartment) in three-dimensional space; typically measured in cubic units; also known as the capacity of the object.

Of or pertaining to measurement by volume.

Spiral-shaped casing which surrounds a pump, blower, or turbine impeller and collects the liquid or gas discharged by the impeller.

Centrifugal pump using a recessed impeller designed to create a whirlpool within the pump casing to convey solids with minimal contact.

Horizontal members of a shoring system placed parallel to the excavation face whose sides bear against the vertical members of the shoring system or earth.

Clean graded media of specified size range, offering a minimum specified void space, having a hardness value of three or greater on the Moh’s scale of hardness (can scratch a copper penny), prepared to be relatively free of fine materials that might otherwise impair absorption area performance; placed on the infiltrative surface.

A critical component of an activated sludge process in which excess cell mass is removed from the treatment train.

Clear water, stormwater, industrial, sewage (domestic or commercial), or any combination thereof, carried by water.

See water reclamation.

See water recycling.

See water reuse.

Constructed basin lined with either soil with very low permeability or a synthetic material, surrounded with berms and which contains at least three feet of wastewater which utilizes sunlight, wind or mechanical aeration, and natural bacteria to break down waste via physical, chemical and biological processes to stabilize wastewater; typically consists of two or more basins with operational controls allowing or facilitating flow through the basins.

Assembly of components for collection, treatment and dispersal of sewage or effluent.

Process of removing biomass from activated sludge in the pretreatment process.

Management of water resources to eliminate waste or maximize efficiency utilizing such methods as using the same water again before it becomes wastewater, installing water-efficient plumbing, or wastewater recycling and reuse.

Method of settling backfill using water.

Specific, measurable, and enforceable standard that establishes limits and measurement frequency for pollutant concentrations or mass loads in treated wastewater discharged to groundwater or surface water.

Treatment or processing of wastewater to produce water of a quality appropriate for another use, including recycling or reuse; see also water recycling and water reuse.

Reclamation process of collection and treatment of wastewater on-site for return and use back into the same site; for example, collection and reclamation of graywater from an establishment for subsequent toilet flushing in that same establishment; see also water reuse.

reclamation process of collection and treatment of wastewater for the deliberate application of that treated wastewater for a beneficial purpose such as turf irrigation; see also water recycling.

Component that removes hardness from a water source.

Reduction in the number of and/or removal of polyvalent cations which are the principal cause of hardness in water.

Upper surface of groundwater or that level in the ground where the water is at atmospheric pressure.

By-product from a water treatment device, such as regeneration water from an ion-exchange unit, reject water from a reverse-osmosis unit, or the backwash from an iron filter.

Well constructed for the purpose of extracting potable water at a beneficial rate.

Toilet specifically designed to receive non-water-carried human waste; includes chemical, composting, pit, and vault toilets.

Drainage basin area contained within the bounds specified by a divide and above a specified point such as a lake, wetland, or stream.

Condition ascribed to a device that is constructed so that no water can move into or out of it except by design through inlets and outlets.

Soil structure descriptor for soil aggregates with wedge-shaped blocks that are larger at the top and narrow at the bottom.

1. Drain hole to allow moisture or air to escape, such as a weep hole in a concrete tank that allows water to drain out of tanks while they are in storage; 2. Drain hole in the discharge assembly that allows drainback to the tank after a dosing event.

Device designed to measure or control flow; consists of a wall or obstruction of known geometric shape placed perpendicular to the direction of flow.

Shaft bored or drilled into the ground for purposes of accessing a saturated zone.

Device with perforations that restricts entry of soil particles while facilitating free drainage of liquid into the well.

Material, usually sand or gravel, with a wide range of particle sizes, with minimum open pore space; also known as poorly-sorted.

Material, usually sand or gravel, with a narrow range of particle sizes with maximum open pore space; also known as poorly-graded and uniformly-graded.

Soil that contains significantly more moisture than moist soil, but in such a range of values that cohesive material will slump or begin to flow when vibrated; granular material that would exhibit cohesive properties when moist will lose those cohesive properties when wet.

Areas that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions; wetlands generally include swamps, marshes, bogs, and similar areas; constructed wetlands used in wastewater treatment are purposely excluded.

Propulsion method using wheels, typically resulting in greater ground pressure due to limited soil contact area; see also tracked.

Soil material of specific size and gradation used to maximize capillary action to draw liquid to the soil surface for evaporation.

Unsaturated flow on the surface of a media or soil particles which moves liquid from a location of greater moisture content to a location with lesser moisture content as a result of capillary action.                                   

Air movement across the liquid surface of a constructed wetland, lagoon or other exposed treatment tank or over a soil treatment area.

Trench; conventional trench; distribution media; biomat; biozone

See mound.

Isolated waste stream consisting of urine collected from specific fixtures and not contaminated by feces or diluted by graywater sources; see also urine separating device.

Portion of a component that is separately managed as a single unit.

See vadose zone.

Layers of soil or rock material surrounding the zone of treatment through which the effluent moves away from the final treatment and dispersal component.

Layer in the ground in which interstitial voids (cracks, crevices, holes, etc.) are filled with water; the level at the top of this zone is the water table.

See biozone.

Valve that mechanically and sequentially diverts the flow of fluid to multiple zones within a soil treatment area.

Jelly-like masses of bacteria found in both the trickling filter and activated sludge processes; masses may be formed for or function as the protection against predators and for storage of food supplies.