Decentralized Wastewater Glossary

See rock fragments

See chemical oxygen demand.

A type of fine-grained soil, such as clay or silt, that has particles that stick together due to their attraction to each other; it is plastic when moist, meaning it can be easily molded, and it retains its shape well; categorized by OSHA as Type A or B, depending upon the compressive strength.

Fibrous organic material originating from coconut husks that may be used in a media filter.

Media filter that uses organic fibric material (coir) from outer husk of coconut as the media; typically packaged as pre-fabricated modular units of containerized media; a type of biofilter.

Group of bacteria that constitute most of the intestinal flora of warm-blooded animals (including the genera Klebsiella sp., Enterobacter sp., Citrobacter sp., or Escherichia sp.) and are used as water pollution indicator organisms.

Virus which uses coliform bacteria as its host cell; also known as a bacteriophage.

See sewage collection system.

See cluster wastewater treatment system.

Very fine solid particles (typically between 0.1 and .001 microns in diameter) which are suspended in a liquid or gas, do not settle out of solution, and cannot be removed by conventional filtration alone.

Unconsolidated, unsorted earth material being transported or deposited on sideslopes and/or at the base of slopes by mass movement (e.g., direct gravitational action); see also alluvium.

Term used to report the estimated number of live non-photosynthetic bacteria in a water sample; see also coliform bacteria, fecal; coliform, total (TC); and heterotrophic plate count.

See Munsell Color System.

Soil structure descriptor for soil aggregates with vertically elongated columns with a distinct rounded cap.

Chlorine that is combined with ammonia in wastewater to form chloramines; although they are slow-reacting, chloramines also serve as disinfectants.

A subset of integrated treatment and dispersal systems that bear American National Standards Institute (ANSI) accreditation and consist of proprietary distribution media installed in a sand layer meeting manufacturer specification for quality (some variation of ASTM C-33 sand criteria) and depth.

Food preparation center that prepares multiple meals or food products and typically generates high-strength wastewater; see also wastewater, high-strength.

Non-toxic, non-hazardous wastewater from commercial establishments, including but not limited to commercial food preparation operations, that is similar in composition to domestic wastewater, but which may have one or more of its constituents exceed typical domestic ranges.

Publicly owned wastewater treatment system for collection, treatment and dispersal of wastewater from two or more lots, or two or more equivalent dwelling units.

Rearrangement of soil grain particles that decrease void space and result in the degradation of soil structure and/or water infiltrative capacity.

Space created by a physical partition within a pretreatment component.

In accordance with OSHA standards, one who is capable of identifying existing and predictable hazards in the surroundings, or working conditions which are unsanitary, hazardous, dangerous to employees, and who has authorization to take prompt corrective measures to eliminate them; see also qualified person.

See continuous-stirred tank reactor.

Subsection of a treatment train or system; a component may include multiple devices; see also part and device.

Commingled individual samples collected from the same point at different times; samples may be of equal volume or may be proportional to the flow at time of sampling.

Self-contained waterless toilet designed to decompose non-water- carried human wastes through microbial action on a carbon source and store the resulting matter for further treatment and reuse/disposal.

Landscape form or feature that is curved or rounded inward such as a segment of the interior of a hollow sphere; slope becomes progressively flatter as one travels downslope.

Artificial construction material prepared by mixing a binding material (cement or lime), fine aggregate (sand), coarse aggregate (stone chips, brick chips or gravel), and water in proper proportion

Deposition of a liquid or a solid from its vapor, generally upon a surface that is cooler than the adjacent gas

Proactive maintenance strategy that includes monitoring equipment condition in real-time using sensors and diagnostics; maintenance is triggered based on the actual condition of the asset, rather than a pre-set schedule.

Impermeable or low-permeability geological formations that restruct groundwater movement, acting as barriers between aquifers.

See soil consistence.

Treatment component that mimics the processes that occur in natural wetlands to renovate wastewater using submerged flow or free water surface configurations and vegetation typically adapted for life in saturated soil conditions.

Activities related to the installation, alteration, extension, or repair of a wastewater treatment system, including all activities from disturbing the soils through connecting the system to the building or property served by the wastewater treatment system.

Survey used to locate structures and provide required elevation points during their construction.

Physical area occupied by personnel, equipment, and materials during the installation, alteration, extension, or repair of a wastewater treatment system; see also limit of disturbance.

See contact chamber.

Tank or compartment where treated effluent mixes with a disinfecting agent; designed to provide sufficient retention time for disinfection to occur.

Time during which a chemical or constituent is in contact with another reacting chemical or constituent such as during chlorine, ozone, or UV disinfection.

Organic or inorganic constituent in suspended or dissolved form that constitutes an impurity targeted for removal from a liquid or solid substrate to facilitate renovation or beneficial use of the treated substrate.

Real-time data recording of process information, including equipment condition and process parameters to identify deviations from normal operation; see also                    condition-based maintenanceand  predictive maintenance.

Reactor in which complete mixing occurs; constituents entering the tank are immediately and evenly dispersed throughout the tank while chemical and biological reactions take place.

Multiple points on the land surface that are of equal elevation.

Vertical distance between level surfaces forming the contours.

Line drawn on a map that connects points having the same elevation.

Movement of liquid dispersed into the receiving environment through the window of acceptance at the downslope edge of the soil treatment area

Cumulative total of effluent applied to the soil profile at the down gradient end of a dispersal system installed on a slope in a time interval, expressed as volume per unit length per unit time along the contour (e.g., gpd/ft-d).

Map consisting of contour lines that illustrate the irregularities of the land surface; also known as a topographic map.

Built or put together by the entity who is installing a system; see also manufacturer-assembled.

Component that contains electrical devices that provide information on system operation and may allow adjustment of settings for operation of electrical devices.

Group of sensors that provide information on and allow adjustment of system settings.

Refers to a typical onsite wastewater treatment system (OWTS) as defined at the local or regional level; see also wastewater treatment system, onsite.

Soil treatment area (STA) configuration consisting of a trench excavation of 3 feet or less using washed rock as the distribution media and containing a single lateral                           

Landscape form or feature that has a surface that is curved or rounded outward; slope becomes progressively steeper as one moves downslope.

1. Condition in which the surface of a component is chemically degraded; 2. condition in which the surface of a concrete component is chemically degraded (dissolving) exposing aggregate and/or structural reinforcement materials; see also spalling.

Specific material placed over system components.

The commonly linear, narrow top of a ridge, hill, or mountain; appropriately applied to elevated areas where retreating backslopes are converging such that these high areas are almost exclusively composed of convex shoulders

Horizontal members of a shoring system installed perpendicular to the sides of the excavation, the ends of which bear against either uprights or wales.

Vertical section of the surface of the ground at right angles to a base line or center line; side view of a cutaway of the earth’s surface.

Non-perforated pipe used in serial or sequential distribution to connect a series of trenches at the same elevation; see also stepdown and relief device.

Preferred configuration of the final grade over onsite wastewater treatment system components intended to ensure that surface water is diverted                    

See interceptor drain.

Process of using excavated material removed from one location as fill material in another location on the same site.

See universal riser

Polyethylene fitting used to connect spray distribution heads to laterals, allowing placement of the distribution head at the soil surface via multiple threaded sections that can be cut to the appropriate length.

Portion of the volute that extends closest to the impeller of a centrifugal pump; shears the circulating liquid or gas and directs flow towards the discharge.

Device used to record the number of times a component or device has been activated (e.g., activation of a pump followed by deactivation is one cycle).

See distribution box.

Estimated volume of wastewater for any 24-hour period; parameter used to size systems.

Measured volume of wastewater generated from a facility in a 24-hour period; expressed as a volume per day.

Level surface to which elevations are referenced; for example, mean sea level.

Come to grade, as with drainage piping.

1. Fifth step in the sequential treatment processes that occur in a sequencing batch reactor (SBR). 2. Act of transferring effluent slowly so as to separate liquid from solid after a previous settling process.

Wastewater treatment system for collection, treatment, and dispersal/reuse of wastewater from multiple homes, isolated communities, industries, or institutional facilities, at or near the point of waste generation.

Removal of the free and combined chlorine residual to reduce the potentially toxic effects of chlorinated effluents.

Bed installed in an excavation greater than 36 inches deep.

Trench installed in an excavation greater than 36 inches deep.

Any change in the inside diameter of piping resulting from installation and imposed loads; deflection may be either vertical or horizontal and is usually reported as a percentage of the base (undeflected) inside piping diameter.

Net amount of effluent applied to a component in a dose or unit time; includes the dose volume minus drainback volume and pipe fill volume; see also dose volume; drainback volume and pipe volume.

Configuration in which a specific volume of effluent is delivered to a component based upon patterns of wastewater generation from the source.

Biochemical reduction of nitrate (NO₃^-) or nitrite (NO₂^-) to gaseous molecular nitrogen (N₂) or an oxide of nitrogen.

Concentrated scented liquid introduced to the exhaust air at the muffler or into the vacuum pump oil reservoir to reduce odors.

Portion of a dosing event during which the distribution system is draining.

1. Process of selecting, sizing, locating, specifying, and configuring treatment train components that match site characteristics and facility use as well as creating the associated written documentation; 2. Written documentation of size, location, specification and configuration of a system.

Estimated volume of wastewater per unit of time for which a component or system is designed.

Service provider who creates plans for the installation, alteration, extension, or repair of a wastewater treatment system; see also service provider.

Average length of time a unit volume of wastewater or a suspended particle remains in a tank or chamber; mathematically, it is the volume of water in the tank divided by the flow rate through the tank (assuming ideal hydraulic conditions).

A loose mass of decaying material.

Subunit of a component; a component often includes multiple devices; see also part and component.

1. To partially remove water from a slurry; 2. To remove water from a basin, tank, reservoir, or other storage unit; 3. To remove water from a site to facilitate construction and installation of components.

A chord passing through the center of a figure or body

Valve employing a stem that depresses a diaphragm (membrane) to control flow.

Method of leveling used to find the difference in elevation (vertical distance) between two points.

Process of introducing air into a treatment component or process through a diffuser using a compressor or blower.

Part or device that injects air under pressure into liquid (e.g., submerged porous plate, perforated pipe, or orifice).