Microsoft Word - Wastewater Dictionary 07-04-2010

7/30/2019 Microsoft Word - Wastewater Dictionary 07-04-2010

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WASTEWATER TRANSITION UNIT

2010

WASTEWATER

DICTIONARY

DOCUMENT MANAGEMENT AND L I B RAR Y S E R V I C E S


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17th

March, 2010


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AAbandonment: discontinued use of a system component or components by removing them or

rendering them inaccessible and inoperable.

Above-grade: soil treatment area designed and installed such that all or part of the infiltrative

surface is located at or above original ground elevation using appropriate imported material; a

final cover of suitable soil stabilizes the completed installation and supports vegetative growth;

includes mounds, areal fill and at-grade; see also at-grade and below-grade.

Absorbent: a substance, a solid or a liquid, that allows another substance, a liquid or a gas, to

permeate it

Absorption: process of incorporation or assimilation by which one substance is physically taken

into and included with another substance; for example, bacteria assimilating nutrients from

effluent.

Absorption area: design parameter described by the square footage of an absorptive surface that

is associated with the hydraulic acceptance of effluent; see also absorptive surface; basal area;

and infiltrative surface.

Absorptive surface: plane of native soil where hydraulic properties change.

Acceptable: condition in which a component is performing its intended purpose and isconsidered to be in an operable state.

Acceptance rate: infiltration of effluent into a designated media expressed as a rate (e.g.,

cm/day); see also long-term acceptance rate.

Access riser: these are installed on the septic tank. They help owners and inspectors easily locate

the tank, and they provide access for maintenance and repair.

Accepted engineering practices: are the requirements which are compatible with standards of

practice required by a registered professional engineer.

Activated carbon: a solid adsorbent material that is used to remove organic pollutants from

liquid or gas streams.


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Activated sludge: (i)highly concentrated mass of live organisms in a suspended growth aerated

and mixed environment. (ii) Sludge clumps produced in aeration tank by the growth of

organisms in the presence of dissolved oxygen.

Activated-sludge process: wastewater treatment process that uses activated sludge to

biologically convert non-settleable (suspended, dissolved, and colloidal) organic materials to a

settleable product using aerobic and facultative microorganisms; typically followed by

clarification and sludge return.

Active aeration: see aeration, active.

Activity/event variables: Variables that provide information on the characteristics of a

particular activity or event that originates from a resource. The activity/event could have both

positive and negative impacts on environmental resources. An activity that is part of the overall

process of economic development may have a positive impact on the economy, but a negativeimpact on a particular resource such as land or water. An activity can also be a response intended

to mitigate the adverse impacts of development or natural disasters.

Additive: product added to a sewage treatment system marketed to improve performance.

Adsorption: adhesion of a substance to the surface of solid bodies or liquids with which it is in

contact.

Aeration, active: introduction of air via either mechanical means or diffused aeration; see also

aeration, passive.

Aeration, diffused: process of introducing air bubbles under pressure into a treatment unit using

a compressor or blower and a diffuser.

Aeration, mechanical: process of introducing air into a treatment component by physical

agitation using a device such as a paddle, paddle wheel, spray nozzle or turbine.

Aeration, passive: process of introducing air into a treatment component without mechanical

means; see also aeration, active.

Aeration chamber: chamber or tank in which wastewater is brought into contact with air to

facilitate biological degradation such as in (but not limited to) the activated sludge process.

Aerated pond: A wastewater treatment pond in which oxygen is incorporated into the

wastewater through mechanical or diffused-air aeration equipment.


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Aeration system: piping, diffusers, air source, vents, and all other necessary devices for an

active aeration process.

Aerobic: (i)having molecular oxygen (O2) as a part of the environment, or a biological process

that occurs only in the presence of molecular oxygen; see also anaerobic and anoxic. (ii)

Aquatic life or chemical processes that require the presence of oxygen. (iii) Wastewater

treatment depending on oxygen for bacterial breakdown of waste.

Aerobic treatment: see treatment, aerobic.

Aerobic treatment unit (ATU): (i) treatment component that utilizes oxygen to degrade or

decompose wastewater, with or without mechanical means; (ii) Term traditionally used to

describe proprietary devices that use direct introduction of air into wastewater by mechanical

means to maintain aerobic conditions within the pretreatment component.

Aggregate: (i) primary soil particles that cohere to each other more strongly than other

surrounding particles; (ii) Naturally-occurring inorganic material (crushed rock or gravel)

screened to sizes for various uses; see also media.

Aggregation: see soil structure.

Air: colorless, odorless, and tasteless gaseous mixture of nitrogen (78%), oxygen (21%) and

trace amounts of other gases.

Air line: see line, air.

Air lock: (i) condition in a pressurized distribution system where the presence of air or other

gases prevents flow; (ii)Condition where air or other gases collect at a high point in a gravity

distribution system and prevent or restrict flow.

Air pollution: Air is made up of a number of gases, mostly nitrogen and oxygen and, in smaller

amounts, water vapour, carbon dioxide and argon and other trace gases. Air pollution occurs

when harmful chemicals and particles are emitted to the air due to human activity or natural

forces at a concentration that interferes with human health or welfare or that harms the

environment in other ways.

Air quality: A measure of the level of pollution in the air.

Air quality criteria: Quantitative criteria indicating levels of pollution and lengths of human

exposure which, if exceeded, may have adverse effects on health and welfare.


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Air release: allowing air to escape during pressurization of a distribution system using an

air/vacuum release valve.

Air source: device which supplies air to a treatment process.

Alarm: device that provides information on the status of a component using a visual and/or

audible device; can either be on site or remotely located.

Alarm activation volume: see volume, alarm activation.

Algal bloom (i) is the rapidly occurring growth and accumulation of algae within a body of

water, which usually results from excessive nutrients or sluggish circulation within a waterbody.

Persistent and frequent blooms can result in low oxygen conditions which is hazardous to aquatic

life. (ii) An unusual or excessive abundance of algae.

Alkalinity:Capacity of a substance to neutralize acid (having a pH above 7.0).

Alluvial: pertaining to processes or materials associated with transportation or deposition of

sediment by water.

Alluvial soil: (i)soil developing from sediments (alluvium) recently deposited by running water

of streams and rivers and exhibiting essentially no horizon development or modification of the

recently deposited materials; (ii)When capitalized, it refers to a great soil group of the azonal

order consisting of soils with little or no modification of the recent sediment in which they are

forming.

Alluvium: sediments deposited by running water of streams and rivers; may occur on terraces

well above present streams, on the present flood plains or deltas, or as a fan at the base of a

slope.

Alteration: modification of a wastewater treatment system on the basis of: an increase in the

volume of permitted flow; a change in the nature of permitted influent; a change from the

planning materials approved by the permitting authority; a change in construction; or an increase,

lengthening, or expansion of the treatment or dispersal system.

Alternating drain fields: final treatment and dispersal component that is comprised of multiple

soil treatment areas which are independently dosed.

Alternative energy sources: Energy that does not come from fossil fuels (such as coal, oil, gas),

for example wind, flowing water, solar energy and biomass.


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Alternative onsite wastewater treatment system: onsite wastewater treatment system that is

not a conventional system as described by local regulatory code.

Alternative technology: Wastewater treatment systems that are new or different from the

standard systems defined in codes and those typically used in a certain area.

Alternating valve: An alternating valve or a switching valve refers to a device that allows

you switch from one absorption field to the other in a gravity type septic system. . See valve,

alternating.

Ambient air: The portion of the atmosphere, external to buildings, to which the general public

has access.

Amenities: Benefits of a property, such as nearby playgrounds, swimming pools, community

centres or parks.

Ammonia: Ammonia, chemical symbol NH3, can take the form of a strong smelling liquid or

gas. Most popularly, consumer and commercial products use the alkaline substance to clean

grime or fertilize crops. Even in low concentrations, inhaling ammonia or getting the solution on

your skin can cause burning, fainting, or death, so always use caution when handling this

chemical. (NH3): see nitrogen, ammonia.

Ammoniacal nitrogen: nitrogen combined with hydrogen in the form of ammonia (NH3) or the

ammonium ion (NH4+); present in sewage, toxic to fish and restricted in discharges to about 5 0-

100 mg/l

Ammonium (NH4+

): The univalent chemical ion NH4+, derived from ammonia, whose

compounds chemically resemble the alkali metals. see nitrogen, ammonium.

Anaerobic: (i)absence of molecular oxygen (O2) as a part of the environment, or a biological

process that occurs in the absence of molecular oxygen; bound oxygen is present in other

molecules, such as nitrate (NO3-) sulfate (SO4+) and carbon dioxide CO2; (ii) Wastewater

treatment in which bacteria breakdown waste without using oxygen. (iii) Microorganisms that do

not require oxygen for their respiratory processes; (iv) an environment in which oxygen is not

available.See also aerobic and anoxic.Amoebae:Anaerobic digester: a tank or vessel which excludes oxygen and in which a sludge or liquid is

modified by the action of anaerobic bacteria.


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Annual plant - A plant that completes its entire life cycle in a single growing season.

Anoxic: (i)condition in which all constituents are in their reduced form (no oxidants present);

conditions in a septic tank are generally anaerobic, but not anoxic; (ii) Describes a water column

or lake with absence of oxygen and presence of nitrate, such as at the bottom of a eutrophic lake

in the summer or under the ice in the winter. (iii) Describes a water column or lake with absence

of oxygen and presence of nitrate, such as at the bottom of a eutrophic lake in the summer or

under the ice in the winter. See also aerobic and anaerobic.

Anthric saturation: variation of episaturation associated with controlled flooding, which causes

a reduced environment in a soil layer and oxidation of mobilized iron and manganese in a deeper

unsaturated subsoil; see also endosaturation and episaturation.

Anti-siphon device: any device in a supply line designed to return pressure to atmospheric

conditions in order to prevent undesired water movement (such as water siphoning out of pumptank); includes valves, vent holes, spit tubes, etc.

Aquic moisture regime: mostly reducing soil moisture regime nearly free of dissolved oxygen

due to saturation by groundwater or its capillary fringe and occurring during periods when the

soil temperature 50 cm (20 inches) below the surface is greater than 5C (41F).

Aquic conditions: continuous or periodic saturation and reduction indicated by redoximorphic

features (RSFs) and verified by measuring saturation and reduction of the soil.

Aquifer: (i) An underground bed or layer of earth, gravel, or porous stone that contains water;(ii) A geological formation, group of formations, or part of a formation that is capable of yielding

a significant amount of water to a well or spring.

Areal fill: above-grade soil treatment area designed and installed such that the entire infiltrative

surface is located above the original ground elevation using suitable imported soil material for

fill; utilizes gravity, pressure-dosed gravity or low-pressure distribution; a final cover of suitable

soil stabilizes the completed installation and supports vegetative growth; see also mound.

Areal loading rate: see loading rate, areal.

As-built: written plan prepared after system installation that reflects the actual construction and

indicates differences from the original design.

Aspirator: device which moves fluid (liquid or gas) by developing a vacuum.


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Assimilation: conversion of absorbed wastewater constituents into living tissue.

Attached-growth process: configuration wherein the microorganisms responsible for treatment

colonize a fixed medium; see also suspended-growth process.

At-grade: above-grade soil treatment area designed and installed such that some part of the

infiltrative surface is located at the original ground elevation using suitable imported soil

material for fill; excavation is 0 to 6 into native soil; utilizes gravity, pressure-dosed gravity or

low-pressure distribution with the orifices of the distribution pipe above the original ground

elevation; a final cover of suitable soil stabilizes the completed installation and supports

vegetative growth; see also above-grade and below-grade. Soil treatment areas with at-grade

trenches (shown in section views): excavation is 0 to 6 inches into original grade and some part

of the infiltrative surface is located at the original ground elevation. Distribution may be gravity,

pressure-dosed gravity or low-pressure distribution to a trench or bed; alternatively, drip

distribution may be used.

Atmosphere: The mass of air surrounding the Earth.

Attrition scrubbing: a process that grinds soil particles together in the presence of a liquid to

remove surface contamination.

Authorization for construction: approval to begin the system installation process.

Autothermal: used to describe the combustion or digestion of a material of sufficient calorific

value or with effective heat recovery so that little or no additional fuel is needed after theinitiation stage.

Axial pump: see pump, axial.

BBNR: see Biological nutrient removal:

BOD5: see biochemical oxygen demand, five day.

Backfill: (i)material placed in an excavation; (ii)to place material in an excavation; (iii) portion

of an excavation above the haunch zone; for straight-walled tanks or structures, that portion of an

excavation above the bedding.


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Backfill, initial: portion of an excavation above the haunch zone or bedding with a depth of 6-12

inches (15 to 30 cm) above the pipe, conduit tank, or structure; see diagram at bedding.

Backfill final: portion of an excavation extending from above the initial backfill to final grade;

see diagram at bedding.

Backflow: reverse direction of flow, with liquid returning to the source.

Backflow prevention device: any device, method, or configuration used to prevent a reversal of

flow.

Back flush: to reverse the direction of flow to clean laterals or filter media; see also backwash.

Back sight (BS or +): rod reading taken on a point of known or assumed elevation (where

establishing the first benchmark, usually assumed as 100.00); the back sight reading is added tothe elevation to determine the Height of Instrument (HI); see also height of instrument (HI).

Back siphonage: a form of backflow which occurs as a result of negative pressure; see also

backflow; anti-siphon device.

Backwash: to reverse the direction of flow through a filter, ion exchange column, or membrane

for cleaning purposes; see also back flush.

Backyard burning: An illegal method of getting rid of household waste, possibly in an attempt

to save on bin charges, which releases levels of pollutants into the air, so harming air quality andrisking the health of those burning the waste and of their neighbours.

Bacteria: Bacteria are microscopic (very tiny) organisms that are unicellular (made up of a

single cell). Bacterium is the term for single bacteria.


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Bacteria, aerobic: bacteria that can metabolize only in the presence of molecular oxygen.

Bacteria, anaerobic: bacteria that is able to metabolize in the absence of molecular oxygen.

Bacteria, coliform: see coliform bacteria, fecal and coliform bacteria, total.

Bacteria, facultative: bacteria that can metabolize with or without molecular oxygen present in

the environment.

Bacteria, mesophilic: bacteria which grow best at temperatures between 20 C and 50 C (68 F

and 122 F) with optimum growth between 25 C and 40 C (77 and 104 F).

Bacteria, psychrophilic: bacteria which grow best at temperatures between 10 C and 30 C (50

F and 86 F) with optimum growth between 12 C and 18 C (54 and 64 F).

Bacteria, thermophilic: bacteria which grow best at temperatures between 35 C and 75 C (95

F and 167 F) with optimum growth between 55 C and 65 C (131 F and 149 F).

Baffle: (i) physical barrier placed in a component to dissipate energy, direct flow, retain solids

and FOG, and/or draw water from a specific depth. (ii) Any deflector device used to change the

direction or flow of water.

Baffle, cargo tank: one or more partitions installed across the shortest dimension of a cargo tank

that partially restrict the free flow of liquid from end to end in the tank; designed to reduce liquid

surge and increase vehicle handling safety.

Baffle, flow restrictor: baffle designed to moderate discharge rate.

Baffle, gas deflector: baffle designed to direct gases and rising solids away from the bottom of

the outlet.

Baffle, inlet: pipe tee or wall segment at or near the inlet pipe of a tank which is designed to

dissipate energy, direct flow below the wastewater surface, isolate scum from the inlet pipe, and

allow ventilation.


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Baffle, outlet: pipe tee or wall segment at or near the outlet pipe of a tank designed to collect

flow from the clear zone, isolate scum from the outlet pipe, and allow ventilation.

Bag filter: textile or sintered polymer filters used to remove dust and fume particles from gas

streams. Used also on liquid waste to provide a final polish or remove floc particles

Balancing tank: provides sufficient storage volume to permit a non-uniform flow of waste water

to be collected, mixed and pumped forward to a treatment system at a uniform rate.

Ball valve: see valve, ball.

Basal area: total area of an above-grade soil treatment area (mound, modified mound, or areal

fill) including the absorption area; perimeter is measured at the interface of imported fill material

and original grade; see also absorption area and infiltrative surface; see diagram at

absorption area.

Base flow The flow in a stream between storm events. The flow is supplied by groundwater.

Batch process: configuration in which flow is controlled so that effluent is neither entering nor

leaving the treatment component while a specific operation is being performed; see diagram at

sequencing batch reactor.

Bed: below-grade soil treatment area consisting of an excavation greater than three feet wide

containing distribution media and more than one lateral; typically installed in an excavation 18 to36 inches below original ground elevation; utilizes pressure or gravity distribution; a final cover

of suitable soil stabilizes the completed installation, supports vegetative growth, and sheds

runoff; see also trench.

Bed, deep: bed installed in an excavation greater than 36 inches deep.

Bed, shallow: bed installed in an excavation less than 18 inches deep such that the entire

infiltrative surface is below the original ground elevation.

Bed, seepage: A trench usually exceeding 36 in. (approx. 1 m) in width containing clean, coarse

aggregate and a system of distribution piping through which treated sewage may seep into the

surrounding soil. See also, bed.


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Bedding: (i) process of laying

appropriate contour; (ii) tampi

support; (iii) material placed unsupport.

Bedrock: general term for the r

any rock strata that is exposed at

Bell-bottom pier hole: a type o

than the cross section above to f

Below-grade: soil treatment ar

most of the sidewall are belostabilizes the completed install

above-grade and at-grade.

Belt press: a device in which w

and dewatering it

Bench level: surveying with a le

a cross section, profile, or topog

Benchmark (BM): referenceestablished with a brass pin or c

specific point on a concrete brid

a few days or weeks until a job i

nail driven in a tree or post; f

(usually 100.00 feet); permanent

book so that a person who had n

seepage bed

a pipe, conduit or other structure in a tren

g earth around a pipe, conduit, or other stru

der a pipe, conduit, tank, or component for u

ock that underlies the soil and other unconsoli

the surface.

shaft or footing excavation, the bottom of whi

rm a bell shape.

a designed and installed such that the infiltr

the original ground elevation; a final coveration, supports vegetative growth, and sheds

ste sludge is compressed between two moving

vel to establish elevations on benchmarks; usu

aphic survey.

point of known elevation; a permanent beap set in concrete, a long metal stake driven in

e or other solid object; a temporary benchmark

s completed) could be a wooden stake driven i

r many temporary benchmarks the elevation

benchmark locations should be accurately des

ver been to the area could find them.

h shaped to the

cture to provide

niform structural

ated material or

h is made larger

tive surface and

of suitable soilrunoff; see also

belts, thickening

lly run as part of

chmark can bethe ground, or a

(needed for only

the ground, or a

may be assumed

ribed in the field


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Benchmark, assumed: temporary benchmark used as a reference; typically assigned an

elevation of 100.00 feet.

Benchmark, referenced: official, permanent point of known elevation; see also monument.

Benchmark, transfer: local benchmark established from a referenced benchmark.

Benching (benching system): is a method of protecting employees from cave-ins by excavating

the sides of an excavation to form one or a series of horizontal levels or steps, usually with

vertical or near-vertical surfaces between levels.

Benthic: (i) Relating to or occurring at the bottom of an aquatic ecosystem. (ii) The bottom zone

of a lake, or bottom-dwelling life forms.

BER: Short for Building Energy Rating, which says how much energy a home needs for heating,

lighting and hot water. Homes are placed on a scale from A to G. A-rated homes need the least

amount of energy while G-rated need the most. Since 1 January 2009, all homes being sold or

rented must have a BER certificate. BER ratings are carried out by BER Assessors registered

with Sustainable Energy Ireland.

Berm: (i)natural or constructed raised drainage feature used to divert runoff (of stormwater) and

direct the flow to an effective outlet; may be used in conjunction with a swale; (ii) Raised

earthen structure designed to contain wastewater such as in a lagoon; see also swale.

Best Management Practice (BMP): (i) actions, behaviors or on-the ground landscaping

practices that reduce pollution and/or the amount of storm water runoff flowing into local

waterways. BMPs can be structural, such as a rain barrel or shoreline buffer, or non-structural,

such as picking up after your pet or washing your car on the grass. (ii) A practice determined by

a state agency or other reliable authority to be the most effective, practicable means of

preventing or reducing pollution.

Bio-accumulation: Build-up of toxic substances in the flesh of fish or other living organisms.

Toxic effects may be passed on to other animals or humans eating the fish.

Biochemical oxygen demand (BOD): (i) amount of oxygen required by bacteria while

stabilizing, digesting, or treating wastewater under aerobic conditions; an indirect measure of the

amount of organic matter in wastewater; a measure of the relative strength of wastewater

expressed in mg/L. (ii) Biochemical Oxygen Demand. Decomposing organics require oxygen.

The BOD5 test measures the oxygen consumed by organisms as they decompose organics over a

five-day period. BOD is thus an indicator of the concentration of organics in water.


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Biochemical oxygen demand, five-day (BOD5): quantitative measure of the amount of oxygen

consumed by bacteria while stabilizing, digesting, or treating biodegradable organic matter under

aerobic conditions over a five-day incubation period; expressed in milligrams per liter (mg/L).

Biochemical oxygen demand, carbonaceous (cBOD): quantitative measure of the amount of

oxygen consumed by bacteria while stabilizing, digesting, or treating the organic matter under

aerobic conditions over a five-day incubation period while in the presence of a chemical inhibitor

to block nitrification; cBOD is expressed in milligrams per liter (mg/L); see also biochemical

oxygen demand, nitrogenous; and nitrification.

Biochemical oxygen demand, nitrogenous (nBOD): quantitative measure of the amount of

oxygen required for the biological oxidation of nitrogenous material (such as ammonia nitrogen

and organic nitrogen) in wastewater; typically measured after the carbonaceous oxygen demand

has been satisfied; nitrification fraction of the BOD5 test; see also biochemical oxygen demand,

five-day; biochemical oxygen demand, carbonaceous; and nitrification.

Biochemical oxygen demand, ultimate (uBOD): oxygen required to complete the oxidation,

synthesis, and endogenous respiration in a sample of wastewater; see also biochemical oxygen

demand, five day.

Biocide: a chemical that is used to kill selected living organisms; for example pesticides,

herbicides, fungicides.

Biodegradable: describes a substance that can be decomposed by microorganisms.

Biodegradable waste: Organic waste, typically coming from plant or animal sources (for

example food scraps and paper), which other living organisms can break down.

Biodiversity: A short form of the phrase biological diversity, which means the variety of life

on this planet and how it interacts within habitats and ecosystems. Biodiversity covers all plants,

animals and micro-organisms on land and in water. See also ecosystem, habitat and organism.

Bioenergy: All types of energy derived from biomass, including biofuels.

Bioengineering: A low-tech construction method using living plants as a functioning, self-sustaining part of the system. Examples include control of erosion of stream banks, water quality

treatment, and flood control and habitat restoration.

Biofilm, biological film or microbial film: a thin slimy layer of microorganisms that develops

on the surface of the media in trickling filters biotowers and contactors and oxidizes organic

material from effluent.


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Biofilter: (i)a media filter in which the media used is biological in origin (i.e., peat or coir).(ii)

Removes odours from gaseous emissions by passing the gas through layers of peat, heather or

similar substrate on which microorganisms grows.

Biofuels: Liquid transport fuels made from biomass.

Biogas: a mixture of methane (CH4) and carbon dioxide (CO2) produced by the anaerobic

digestion of sludges or organic material in landfill sites; can be used to generate heat or power.

Biological aerobic organisms: Living organisms that break down organic solids in the presence

of oxygen into inorganic and stable organic solids.

Biological filter: a packaged treatment system that removes biological oxygen demand (BOD)

and suspended solids from relatively small flows of sewage or industrial wastewater by passing

the effluent over plastic media on which aerobic biofilm develops.

Biological loading rate: see loading rate, biological.

Biological nutrient removal (BNR): use of microbiological activity for removal of nitrogen and

phosphorus in a wastewater treatment system.

Biological oxygen demand (BOD): The amount of oxygen required by aerobic microorganisms

to decompose the organic matter dissolved or suspended in water. Used as a measure of the

degree of water contamination.

Biological treatment: see treatment, biological.

Biomass: (i) total mass of living organisms. (ii) The amount of organic material of biological

origin in a given area or volume. (iii) A source of fuel made from living and recently-dead plant

materials such as wood, leaves and the biodegradable part of industrial and municipal waste.

Biomat: layer of biological growth and inorganic residue that develops at the infiltrative surface.

Biofilm: thin coating of microbial growth, organic matter, and microbial secretions on a solid

substrate particle.

Bioremediation: a treatment that enhances the ability of naturally occurring or cultured

microorganisms to degrade organic pollutants in soil.

Bioretention A water quality practice that utilizes landscaping and soils to treat stormwater by

collecting it in shallow depressions and then filtering it through a planting soil media.


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Biosolids: dewatered, primarily nutrient-rich organic material generated as a byproduct of

biological wastewater treatment processes that can be recycled (such as for use as a soil

amendment); see also residuals and septage.

Biota: All living organisms that exist in an area.

Biotower: an above ground structure containing plastic media covered in microbial film that

reduces the BOD/COD/Ammonia of industrial liquid effluent flowing over it.

Biozone: zone of biologically active treatment in soil, fill, or other media; see also zone of

treatment.

Black bin (grey bin): A wheelie bin used in certain local authorities to collect waste that cannot

be recycled or composted.

Blackwater: portion of the wastewater stream that originates from toilet fixtures, dishwashers,

and food preparation sinks; see also graywater.

Bleed: to drain a liquid or gas, as in bleeding accumulated air from a water line or bleeding

(draining) a trap of accumulated water.

Blower, air: device that uses a fan to deliver air to a component; does not substantially compress

air.

Boot: flexible device attached to piping to provide a watertight seal.

Bottomless media filter: see filter, bottomless media.

Boundary stations: Stations making up part of a water monitoring network and are intended to

describe fluxes, either between legal boundaries or between submedia (from a river to a lake or

ocean, or from a surface stream to groundwater).

Bring bank: A place where you can bring materials for recycling, for example glass,

newspapers, heavy cardboard and textiles. See also recycling centre and civic amenity site.

Brown bin: A wheelie bin used in some local authorities to collect organic waste such as food

and light garden waste (for example grass cuttings).

Bubble, coarse: bubble of 3 to 8 mm diameter generated by an air diffuser.

Bubble, fine: bubble of 0.2 to 3 mm diameter generated by an air diffuser.


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Bubble, micro: bubble of less than 0.2 mm diameter generated by an air diffuser.

Buffer (i) A vegetated strip immediately adjacent to a water body. The primary function of the

buffer is to protect the receiving waterbody from sediment and pollutants derived from upstream

areas. (ii) An area of trees, shrubs and plants next to a waterbody designed to protect the

receiving waterbody from sediment and pollutants contained in storm water runoff. Buffers also

function as habitat for migratory birds and aquatic and terrestrial wildlife.

Bulking: inability of sludge solids to separate from the liquid under quiescent conditions; under

aerobic conditions may be associated with the growth of filamentous organisms, low Dissolve

oxygen (DO), or high sludge loading rates; under anaerobic conditions, may be associated with

attachment of gas bubbles to solids.

Building sewer: arepipe that conveys wastewater to the first system component or the sewermain.

Bundled pipe: distribution media consisting of two or more co-joined perforated pipes.

Buoyancy: tendency of a body to float in water or other liquid; upward force that a fluid exerts

on an object that is less dense than itself.

Buoyancy valve: see valve, buoyancy.

Bury depth: depth from the surface of the finished grade to the top of a component.

Bye-law: A rule made by a local authority to govern activities within the area it controls.

Examples include bye-laws covering waste disposal, traffic or public events or signs.

CCBOD: see biochemical oxygen demand, carbonaceous.

Cadmium: toxic heavy metal to which the most stringent discharge standards apply; a

prescribed red list compound with an environmental quality standard (EQS) of 5 -g/l

Carbonaceous matter: Pure carbon or carbon compounds present in the fuel or residue of a

combustion process.


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Carbon count: A measure of the amount of carbon dioxide you produce through your lifestyle

every day, for example through driving or using electrical appliances and lighting.

Carbon credit: A unit of carbon dioxide bought to reduce greenhouse gas emissions. See carbon

offset.

Carbon dioxide (CO2): A colourless gas that is naturally produced from animals and people in

exhaled air and the decay of plants. It is removed from the atmosphere by photosynthesis in

plants and by dissolving in water, especially on the surface of oceans. The use of fossil fuels for

energy is increasing the concentration of carbon dioxide in the atmosphere, which is believed to

contribute to global warming. See also greenhouse gases and photosynthesis.

Carbon emissions: In the context of climate change, carbon dioxide released when substances,

especially oil, gas, and coal, are burned by vehicles and planes, by factories and by homes.

Carbon footprint: A measure of the impact our activities have on the environment, especially

climate change, often reported as the units of tonnes (or kg) of carbon dioxide each of us

produces over a given period of time.

Carbon monoxide: A highly poisonous, odourless, tasteless and colourless gas that is formed

when carbon material burns without enough oxygen. Carbon monoxide is toxic when inhaled

because it combines with your blood and prevents oxygen from getting to your organs. If a

person is exposed to carbon monoxide over a period, it can cause illness and even death. Carbon

Monoxide has no smell, taste or colour. This is why it is sometimes called the Silent Killer.

The most common causes of carbon monoxide poisoning in the home are house fires, faulty

heating appliances such as boilers, blocked chimney or flues, and rooms not properly ventilated.

Carbon Monoxide alarms can be used as a backup to provide a warning to householders in the

event of a dangerous build up of carbon monoxide.

Carbon neutral: A situation that arises when the amount of carbon dioxide released into the air

equals the amount of carbon dioxide removed from the air, for example by planting trees, or the

amount saved by using renewable energy sources to produce the same amount of energy. See

also renewable energy.

Carbon offset: A unit, equal to one ton of carbon dioxide, that individuals, companies orgovernments buy to reduce short-term and long-term emissions of greenhouse gases. The

payment usually funds projects that generate energy from renewable sources such as wind or

flowing water. Individuals can choose whether to buy an offset (for example to compensate for

air travel), but governments and large industries are sometimes required to buy them to meet

international targets aimed at reducing greenhouse gases.


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Carbon tax: A tax on fuels according to their carbon content, which aims to encourage people

and businesses to use fuels with less carbon and reduce the amount of energy they use.

Cargo tank: see tank, cargo.

Cargo tank baffle: see baffle, cargo tank.

Carpooling: Sharing a car to a destination to reduce fuel use, pollution and travel costs.

Catalyst: a substance which increases the rate of a chemical reaction without being consumed in

the reaction.

Catalytic incinerator: device in which the use of catalysts allows the combustion of solvent

vapours and other VOCs to be carried out at relatively low temperatures.

Cave-in: separation of a mass of soil or rock material from the side of an excavation, or the lossof soil from under a trench shield or support system, and its sudden movement into the

excavation, either by falling or sliding, in sufficient quantity so that it could entrap, bury, or

otherwise injure and immobilize a person.

Cavitation: phenomenon that may occur when a centrifugal pump attempts to discharge more

flow than it is pulling in through the suction; reduced internal, pressure causes gases to expand

and form bubbles around the impeller; and the bubbles violently implode, potentially causing

damage to the pump.

Centralized wastewater treatment system: A wastewater treatment system in which the

wastewater is collected from many homes and treated at a single facility and nearly always

discharged to a surface water body.

Centrifuge: a device that separates solid material, sludges or oil from liquid effluents by rapid

rotation.

Centrifugal pump: A centrifugal pump is a rotodynamic pump that uses a rotating impeller to

increase the pressure of a fluid. Centrifugal pumps are commonly used to move liquids through a

piping system. The fluid enters the pump impeller along or near to the rotating axis and isaccelerated by the impeller, flowing radically outward into a diffuser or volute chamber (casing),

from where it exits into the downstream piping system. Centrifugal pumps are used for large

discharge through smaller heads. See pump, centrifugal.


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Certificate of completion: documentation of the proper construction of the system.

Certificate of compliance: A document reporting the results of an inspection of a system to

determine its compliance or noncompliance with applicable requirements in force at the time of

the inspection.

Certification: program to substantiate the capabilities of personnel by documentation of

experience and learning in a defined area of endeavor.

Cess pit: see cesspool.

Cesspool: underground pit into which raw household wastewater is discharged and from which

the liquid seeps into the surrounding soil; may or may not be partially lined; if septic tank

effluent is discharged to such a component it is considered a seepage pit.

Chain trencher: see trencher.

Chamber: pre-formed manufactured distribution medium with an open-bottom configuration

commonly used in soil treatment areas.

Check dam - A small barrier built across the direction of water flow in a swale to retain excess

water during heavy rains and to slow the speed of runoff traveling through the swale.

Check valve: see valve, check.

Chemical oxygen demand (COD): (i)amount of the organic matter in wastewater that can be

oxidized by a very strong chemical oxidant; typically measured by a standard test using

dichromic acid as the oxidant. (ii) The COD test measures the chemical oxidant required to break

down organics. COD is an indicator of the concentration of organics in water. The COD test can


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be completed in a few hours and is frequently substituted for BOD. COD levels are usually

greater than BOD for a given wastewater. See chemical oxygen demand.

Chemical treatment: see treatment, chemical.

Chisel plow: see plow, chisel.

Chloramine: chemical compound present as a result of the chlorine disinfection process when

the effluent contains ammonia; chloramines are relatively persistent in the environment and toxic

to fish and amphibians.

Chlorinated hydrocarbons: organic compounds containing the elements carbon, hydrogen and

chlorine, implicated in low level ozone production and high level ozone destruction.

Chlorination: The application of chlorine to water or wastewater for the purpose of disinfection,

oxidation, odor control or other desired effects. See disinfection, chlorine.

Chlorinator: component that delivers chlorine (liquid, tablet, or gas) as an agent for is infection.

Chlorine: term commonly used to describe a chlorine source such as sodium hypochlorite, a

highly reactive chemical used as a disinfectant and oxidizing agent.

Chlorine, combined available: chlorine that has combined with ammonia in wastewater to form

chloramines; although they are slow-reacting, chloramines also serve as disinfectants.

Chlorine, free available: quantity of hypochlorous acid (HOCl) and hypochlorite ions (OCl )

present after the introduction of chlorine for disinfection purposes; the relative distribution of

these is affected by pH and temperature with lower pH favoring hypochlorous acid which has

significantly higher germicidal efficiency than hypochlorite ions.

Chlorine disinfection: see disinfection, chlorine.

Chlorine residual: total amount of chlorine (free and combined available forms) remaining in

water, sewage, or industrial wastes at the end of a specified contact period after the chlorination

process.

Chlorofluorocarbons (CFCs): which are chemicals used in manufacturing and, in the past, in

aerosol cans and refrigerators, which can damage the ozone layer.


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Chroma: relative purity, strength, or saturation of a color; directly related to the dominance of

the determining wavelength of the light and inversely related to grayness; one of the three

variables of color; see also Munsell Color System; hue; and value.

Chromium: a toxic heavy metal that may contaminate groundwater; stringent environmental

discharge limits apply.

Civic amenity site: A public or private facility that accepts recyclable and non-recyclable

materials such as garden and household waste and certain hazardous wastes such as paints,

batteries and electrical and electronic devices. See also bring bank, recycling centre and WEEE.

Clarification: process or combination of processes that uses separation (settling and floatation)

to remove suspended solids from wastewater.

Clarifier: (i) component or tank that uses separation to remove suspended solids from

wastewater. (ii) A settling tank, sedimentation tank or basin in which wastewater is held for a

period of time to allow the heavy solids to settle to the bottom and the lighter solids to float to

the surface.

Class C wastewater treatment operator: An operator licensed by the Minnesota Pollution

Control Agency to manage and operate a municipal wastewater treatment plant under the terms

and licensure of a Class C level license.

Clay: (i)soil separate consisting of particles


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Clear zone: volume or zone within a component that contains clarified wastewater; for example,

after wastewater has had sufficient detention time in a septic tank, the clear zone lies between the

scum and sludge layers.

Clear zone of a two-compartment septic tank

Climate: The pattern of weather in a particular region over a set period of time, usually 30 years.

The pattern is affected by the amount of rain or snowfall, average temperatures throughout the

year, humidity, wind speeds and so on. Ireland has a temperate climate, in which it doesnt get

too hot or too cold.

Climate change: A change in the climate of a region over time due to natural forces or human

activity. In the context of the UN Framework Convention on Climate Change, it is the change in

climate caused by higher levels of greenhouse gases in the atmosphere due to human activities as

well as natural climate changes. See also global warming, and UN Framework Convention on

Climate Change.

Clogging mat: Continuous or frequent ponding of septic tank effluent on the bottom of the

disposal field results in the growth of a biological layer that filters out more and more solid

particles and dissolved pollutants from the septic tank effluent. A clogging mat is formed at the

point of infiltration into the soil. This mat normally penetrates 1/2 to 6 centimeters into the soil.

It consists of a slimy mass of septic tank effluent solids, mineral precipitates, microorganisms,

and the by-products of decomposition. Microorganisms in the mat feed on septic tank effluent

nutrients to produce slimes, polysaccharides, carbon dioxide, etc. Filtered-out cellulose,

undigested food residues, etc., hydrolyze and biodegrade slowly. Mineral precipitates, such asferrous sulfide, etc., also contribute to the clogging mat. The clogging mat is in constant flux,

which is, building, degrading, and creeping downward into the soil as a viscous fluid where it is

dispersed. The process is self-cleaning; otherwise, disposal fields could not last more than a few

years. This self-cleaning property, along with a constant septic tank effluent load, allows a

properly designed disposal field to be passive and function without maintenance. The clogging

mat develops at a rate dependent upon the septic tank effluent load. As the clogging mat matures,

the septic tank effluent infiltration rate through the clogging mat decreases. A clogging mat's

average infiltration rate, or disposal field application rate, is usually reached after a period of 3 to

36 months. See also, Biomat.

Cluster system: There are many definitions of a cluster system. The most used is that cluster

systems serve a number of structures with more than one and as many as hundreds of

connections. Also known as community systems, cluster systems are a treatment option when

traditional onsite systems (a single system for each structure) or the extending of sewers are not

viable alternatives. The decision regarding which type of system to use remains based on a sites


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soils, groundwater and bedrock elevation, topography, and regulatory requirements. Similar to

individual onsite systems, cluster systems typically treat and dispose of effluent within the

development limits. Subsurface, non-point discharges are the norm; however surface discharge is

also an option. One of the benefits with cluster systems is that they offer a wide range of

methods available to collect, treat, and dispose of the effluent. This allows the designer to choose

the most cost-effective technology that is appropriate for the community. See wastewater

treatment system, cluster.

Coagulation: (i) the process by which colloidal particles come together irreversibly to form

larger masses. (ii) a process that alters the surface charge on dispersed colloidal particles in a

liquid so that they are able to agglomerate; the first stage in floc formation.

Coir filter: see filter, coir.

Coarse fragments: see rock fragments

Cold Climate Limitations: Cold temperatures, ice cover, plant dormancy, equipment

performance, ice buildup and reduced microbial action create design challenges for cold weather

wastewater treatment.

Coliform bacteria: 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.

Coliform bacteria, fecal: indicator bacteria common to the digestive systems of warm-bloodedanimals that is cultured in standard tests to indicate either contamination from sewage or the

level of disinfection; generally measured as number of colonies/100 mL or most probably

number (MPN); see also most probable number.

Coliform index: A rating of the purity of water based on a count of fecal bacteria.

Coliform, total (TC): measurement of water quality expressed as the number of colony-forming

units (cfu) of coliform bacteria per unit volume; see also colonyforming unit (cfu) and

heterotrophic plate count.

Coliphage: virus which uses coliform bacteria as its host cell; also known as a bacteriophage.

Collection system: see sewage collection system.


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Colloids: 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.

Colony-forming unit (cfu): 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.

Color: see Munsell Color System.

Combined heat and power (CHP): system designed to use the heat produced during the

generation of electricity; can be coupled to the incineration of solid waste.

Combined Sewers: This is a sewer system in which the storm water and sanitary waste are

combined. A benefit is that non-point pollution flushed from the watershed during moderate rain

is treated, but the system can be overwhelmed during severe storms, resulting in untreated waste

being flushed into the receiving waters as a combined sewer overflow (CSO).

Combination wastewater system: (Also referred to as dual or separation technology or

treatment train.) This is a wastewater treatment system that uses more than one technology to

treat the wastewater. Frequently one of the technologies is a composting or incinerating toilet

and the other is a septic tank/drainfield or an aerobic tank with a soil treatment and dispersal unit

used for the balance of the wastewater.

Commercial kitchen: food preparation center that prepares multiple meals or food products andtypically generates high-strength wastewater; see also wastewater, high-strength.

Comminutors: Devices such as grinders, cutters and shredders used to reduce the size of solids

found in wastewater.

Compaction: rearrangement of soil grain particles that decrease void space and result in the

degradation of soil structure and/or water infiltrative capacity.

Compact fluorescent lamp (CFL) bulbs: which are light bulbs that use a fraction of the energy

of traditional filament bulbs and last up to five times longer. CFL bulbs will completely replacefilament bulbs in Ireland by 1 September 2012.

Compactor, vibratory: mechanical device that consolidates loose soil material such as a

jumping jack.

Compartment: space created by a physical partition within a pretreatment component.


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Compensation: payment for services rendered.

Competent person: one who is capable of identifying existing and predictable hazards in the

surroundings, or working conditions which are unsanitary, hazardous, or dangerous to

employees, and who has authorization to take prompt corrective measures to eliminate them; see

also qualified person.

Compliance inspection: An evaluation, investigation, inspection or other such process to

determine if a treatment system meets the entire applicable local and state requirements, which

usually results in a certificate of compliance or a notice of noncompliance being issued.

Compliant septic system: An individual or multiple household wastewater treatment system

that meets all applicable local ordinances.

Component: subsection of a treatment train or system; a component may include multiple

devices; see also part and device.

Composite sample: A sample of water that is a mixture of grab samples of equal or weighted

volume, all collected at the same location at different points of time. Also known as a time

composite, these samples are useful for assessing the average concentration or load of pollutants.

See also sample, composite.

Compost: A rich soil-like material produced from decayed plants and other organic matter, such

as food and animal waste, that decomposes (breaks down) naturally. Most food waste can be putinto compost, but you should not include meat, bones, cheese, cooking oils and fish. These may

take a long time to break down and attract unwanted pests.

Compostable: Material from plants or animals that can be used to create compost because it will

decompose naturally over time.

Composting: The process by which you deliberately allowing food, garden and other suitable

organic wastes to break down naturally over time to produce compost.

Compressor, air: device that delivers pressurized air to a component.

Condenser: removes high concentrations of solvent vapours from gas streams by cooling,

allowing both the liquid solvent fraction and the gas to be recycled or otherwise treated.

Conductivity, hydraulic: see hydraulic conductivity.


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Conservation: Preserving or protecting animals and resources such as minerals, water and plants

through planned action (such as breeding endangered species) or non-action (such as not letting

taps run unnecessarily).

Consistence: see soil consistence.

Constructed wetland: (i) pretreatment component that incorporates appropriate moisture

tolerant vegetation and consists of one or more lined basins where wastewater undergoes some

combination of physical, chemical, and/or biological treatment; configurations include free

surface and submerged flow configurations. (ii) A wetland constructed for the purpose of

pollution control and waste management. The flow rate, residence time and other factors are

controlled to enhance the removal of BOD, SS, and N. A waterproof barrier is usually placed

below the substrate to isolate the wastewater form the groundwater. Plants such as cattails,

bulrushes and reeds provide a dense cover and an oxygenating substrate for bacteria in the root

zone.

Constructed wetland system, free water surface: is a constructed wetland in which

wastewater is exposed at the surface of the media.

Constructed wetland system, submerged flow: areconstructed wetlands in which wastewater

passes through the component below the surface of the media.

Construction: any activity 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.

Construction zone: are 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.

Contact stabilization: an activated sludge process that produces less surplus sludge; separated

sludge is aerated vigorously before it contacts and stabilises raw sewage.

Contact time: time during which a chemical or constituent is in contact with another reacting

chemical or constituent such as during chlorine, ozone or UV disinfection.

Contour: multiple points on the land surface that are of equal elevation.

Contour interval: vertical distance between level surfaces forming the contours.

Contour line: line drawn on a map that connects points having the same elevation.


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Contour loading rate: see loading rate, contour.

Contour map: map consisting of contour lines that illustrate the irregularities of the land

surface; also know as a topographic map.

Contractor-assembled: built or put together by the entity who is installing a system; see also

manufacturer-assembled.

Control panel: component that contains electrical devices that provide information on system

operation and may allow adjustment of settings for operation of electrical devices.

Controls: group of sensors that provide information on and allow adjustment of system settings.

Conventional system: refers to a typical Onsite Wastewater Treatment System (OWTS) asdefined at the local or regional level; see also wastewater treatment system, onsite.

Corrosion: (i) condition in which the surface of a component is chemically degraded; (ii)

condition in which the surface of a concrete component is chemically degraded (dissolving)

exposing aggregate and/or structural reinforcement materials; see also spalling.

Counter, alarm: device used to record the number of times an alarm has been activated.

Counter, cycle: 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).

Counter, event: device used to record the number of times a component or device has been

activated or deactivated (e.g., pump activation is one event and pump deactivation is a second

event).

Cover: specific material placed over system components.

Cross braces: horizontal members of a shoring system installed perpendicular to the sides of the

excavation, the ends of which bear against either uprights or walls.

Cross section: 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 earths surface.

Cross-over pipe: arenon-perforated pipe used in serial or sequential distribution to connect a

series of trenches at the same elevation; see also step-down and relief device.


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Cryptosporidium: (i)a protozoan parasite causing diarrhea in humans and other animals; the

pathogen is spread in water as spherical oocysts 5 m diameter, resistant to chlorine treatment.

(ii) Is a tiny parasite that can infect people if it is present in drinking water.

Curtain drain: see drain, interceptor.

Cut and fill: process of using excavated material removed from one location as fill material in

another location on the same site.

Cyanides: toxic inorganic chemical compounds containing cyanide (-CN) groups and classed as

special waste.

Cyclone: a device in which a gas stream is spun and coarse grit and dust particles are thrown

outwards to the cyclone wall where they are guided into a hopper.

DD-box: see distribution box.

Dissolved oxygen (DO): is the measure of the amount of oxygen available for biochemical

activity in a given amount of water. Adequate levels of DO are needed to support aquatic life.

Low concentrations can result from inadequate waste treatment.

DWV (Drain-waste-vent): (i) assembly of pipes which facilitates the removal of liquid and

solid wastes as well as the dissipation of sewer gases; (ii)pipe specified for use in the removal of

liquid and solid wastes and for the dissipation of sewer gases.

Daily flow: see flow, daily.

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

Decant: act of transferring effluent slowly so as to separate liquid from solid after a previous

settling process.

Decentralized wastewater treatment system: see wastewater treatment system,

decentralized.

Dechlorination: removal of the free and combined chlorine residual to reduce the potentially

toxic effects of chlorinated effluents.


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Deciduous plant: A plant that sheds or loses its foliage at the end of each growing season.

Deflection: any change in the inside diameter of a pipe 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 pipe diameter.

Deforestation: The reduction of trees in a wood or forest due to natural forces or human activity

such as burning or logging.

Denitrification: biochemical reduction of nitrate (NO3-) or nitrite (NO2

-) to gaseous molecular

nitrogen (N2) or an oxide of nitrogen.

Deodorizer: concentrated scented liquid introduced to the exhaust air at the muffler or into the

vacuum pump oil reservoir to reduce odors.

Depressurized flow: see flow, depressurized.

Design: (i) 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; (ii) written documentation of size, location, specification and

configuration of a system.

Design flow: see flow, design.

Designated use Uses specified in water quality standards for a waterbody. For instance,Greenfield Lake is classified c by the NC Division of Water Quality, meaning its main use is

aquatic life propagation, general use, fishing and non-body contact recreation like canoeing.

Designer: service provider who creates plans for the installation, alteration, extension, or repair

of a wastewater treatment system.

Desorption: the removal of adsorbed gas or liquid molecules from the surface of a solid.

Desulphurisation: the removal of sulphur compounds from flue gas in the form of solid sulphur

or as calcium sulphate (gypsum).

Detention time: (i)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). (ii) (Retention time;

residence time) the average period of time wastewater stays in a treatment system. Detention


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times vary for different types of wastewater treatment systems and can range from hours to

weeks.

Development plan: A public plan that sets out the development objectives and policies of a

local authority for its area. It covers a six-year period and states the local authoritys goals for a

range of areas such as maintaining and improving roads and parks, preserving and enhancing

amenities (such as playgrounds or swimming pools), zoning land for homes, businesses, factories

and farming and providing services and facilities such as waste disposal and sewerage. Members

of the public have opportunities to make submissions on the plan before it is agreed.

Device: subunit of a component; a device often includes multiple components; see also part and

component.

Dewater: (i) to partially remove water from slurry; (ii) to remove water from a basin, tank,

reservoir, or other storage unit; (iii) to remove water from a site to facilitate construction and

installation of components.

Differential leveling: method of leveling used to find the difference in elevation (vertical

distance) between two points.

Diffuser: part or device that injects air under pressure into wastewater (e.g., submerged porous

plate, perforated pipe, or orifice).

Digestion: the enzymatic breakdown of large insoluble organic molecules into small soluble

organic molecules which can be absorbed and used by either aerobic or anaerobicmicroorganisms.

Dioxins: (i)a group of toxic organic substances, containing carbon, hydrogen, oxygen and

chlorine, resistant to biodegradation, produced when organic material is incinerated at low

temperatures. (ii) Highly toxic chemicals that can be formed in small amounts from forest fires

or volcanoes but more often are produced unintentionally from industrial activities and from

incinerating waste and burning fossil fuels.

Discharge assembly: all piping and parts between the point of pump discharge to the point at

which the supply line exits the tank.

Discharge assembly showing associated components. When check valves are used in cold

climates, a weep hole is usually drilled above the check valve to allow drain back after each

dose, thereby preventing freezing of liquid in the supply line.


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Disinfection: process used to destroy or inactivate pathogenic microorganisms in wastewater to

render them non-infectious; see also disinfection, chlorine; disinfection, ozone; and

disinfection, ultraviolet (UV).

Disinfection, chlorine: process used to inactivate microorganisms by the addition of chlorine in

the form of sodium hypochlorite; see also chlorine.

Disinfection, ozone: process used to inactivate microorganisms via the application of ozone to

wastewater; see also ozone.

Disinfection, ultraviolet (UV): process used to inactivate microorganisms by irradiating them

with ultraviolet light to disrupt their metabolic activity, thus rendering them incapable of

reproduction; see also ultraviolet.

Dispersal: spreading of effluent over and into the final receiving environment.

Dispersion: (i) scattering and mixing; (ii) repellant action of an electric potential on fine

particles in suspension in water, as in streams carrying clay.

Disposal, dispose of: In this guide, getting rid of waste by discarding it into a bin and, when it is

collected, by incinerating it or sending it to landfill.

Dissolved air flotation (DAF): isa method of dissolving pressurised air into a liquid to form

small bubbles that will float material to the surface.

Dissolved oxygen (DO): (i)amount of molecular oxygen (O2) dissolved in water, wastewater, or

other liquid; commonly expressed as a concentration in milligrams per liter (mg/L), parts per

million (ppm), or percent of saturation. (ii) The amount of oxygen that is dissolved in water. It

also refers to a measure of the amount of oxygen available for biochemical activity in a

waterbody and as indicator of the quality of that water.

Distribution: the process of conveying wastewater or effluent to one or more components or

devices.

Distribution, drip: application of effluent over an infiltrative surface via pressurized emitters

and associated devices and parts (pump, filters, controls, and piping).

Drip distribution treatment train (typical)

Distribution, gravity: using the force of gravity to convey wastewater or effluent to one or more

components or devices; gravity distribution to trenches may be parallel, sequential or serial; see

also distribution, parallel; distribution, sequential; and distribution, serial.


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Distribution, low pressure (LPD): (i) application of effluent over an infiltrative surface via

pressurized orifices and associated devices and parts (including pump, filters, controls, and

piping). (ii) Distribution via a network of small diameter laterals (typically 1 -inch) with small

orifices (typically 1/8- to 3/16-inch) installed in a soil treatment area; also called low-pressure-

pipe (LPP) distribution. Below-grade soil treatment area illustrating trenches with low-pressure

distribution; low pressure distribution can also be used in mound, areal fill, at grade and bed soil

treatment areas, as well as in media filters.

Distribution, parallel: pressure or gravity distribution of effluent that proportionally and

simultaneously loads multiple sections of a final treatment and dispersal component.

Distribution, pressure: using a pump or siphon to convey wastewater effluent under pressure to

one or more components or devices.

Distribution, pressure-dosed gravity: gravity distribution of effluent over an infiltrative

surface via one or more trenches or a bed following pressure dosing to a manifold or other flow

splitter; also known as pump to gravity. Trenches with pressure-dosed gravity parallel

distribution

Distribution, sequential: distribution method in which effluent is loaded into one trench and

fills it to a predetermined level before passing through a relief line or device to the succeeding

trench; the effluent does not pass through the distribution media before it enters succeeding

trenches; see also distribution, serial. Trenches with gravity sequential distribution

Distribution, serial: distribution method in which effluent is loaded into one trench and fills it to

a predetermined level before passing through a relief line or device to the succeeding trench;

effluent passes through the distribution media before entering succeeding trenches which may be

connected to provide a single uninterrupted flow path; see also distribution, sequential.

Trenches with gravity serial distribution

Distribution, spray: application of effluent over an infiltrative surface via pressurized nozzles

and associated devices and parts (including pump, filters, controls and piping).

Distribution box (D-box): level, watertight structure that receives septic tank effluent and

distributes it via gravity in approximately equal portions to two or more trenches or two or more

laterals in a bed.

Distribution device: device that receives effluent from one component, and conveys it to a

subsequent component(s), (e.g., a distribution box, drop box, or manifold).


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Distribution lateral: see lateral.

Distribution media: see media, distribution.

Distribution rock: clean graded rock or gravel of specified size range, offering a minimum

specified void space, having a hardness value of three or greater on the Mohs Scale of Hardness

(can scratch a copper penny), washed or prepared to be relatively free of fine materials that

might otherwise impair absorption area performance; placed on the infiltrative surface.

Distribution system: entire network of components that transport wastewater or effluent within

a system.

Distribution uniformity: variability of effluent delivery.

Diversion valve: see valve, alternating.

Domestic charges: Fees paid to local authorities for providing services such as collecting

domestic waste.

Domestic waste: Waste produced within the home, including garden waste. See also household

waste.

Domestic wastewater: is wastewater discharged from residences and from commercial,

institutional and similar facilities; also known as wastewater or sanitary wastewater. Seewastewater, residential strength.

Dose: see dosing event or volume, dose.

Dose cycle: period between the initiation of one dosing event and the next; the period includes

both the time on and the time off.

Dose volume: See volume, dose.

Dosing, demand: configuration in which a specific volume of effluent is delivered to acomponent based upon patterns of wastewater generation from the source.

Dosing, timed: configuration in which a specific volume of effluent is delivered to a component

based upon a prescribed interval, regardless of facility water use; see also flow equalization.

Dosing chamber: see tank, dosing.


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Dosing device: are pumps, siphon, or other device that delivers effluent to a subsequent

component in a treatment train.

Dosing event: is occurrence of effluent delivery after a rest period.

Dosing tank: see tank, dosing.

Down gradient: (i) direction water flows by gravity; (ii) location down-slope.

Drag-out bath: container of water in which metal plated objects are rinsed to remove excess

plating solution.

Drain, curtain: see drain, interceptor.

Drain, French: see drain, interceptor.

Drain, interceptor: subsurface drain used to intercept and divert laterally moving groundwater

or perched water away from the soil treatment area or other system component to an effective

outlet; also known as an interceptor drain; see also drain, perimeter.

Drain, perimeter: subsurface drain installed around and outside of an individual soil treatment

area or zone and designed to actively or passively lower the water table.

Drainage: network of natural or artificial groundwater or surface water features includingagricultural drain tile, cut banks, and ditches which intercept and divert surface water and/or

lower groundwater.

Drainage class (natural): group of soils defined by frequency and duration of wet periods

similar to those under which the soil developed.

Drainage, tile: large-scale subsurface drainage system designed for lowering groundwater for

agricultural purposes.

Drain back: backflow of effluent into a pump tank after a dosing event; see also volume, drain

back.

Drain back volume: see volume, drain back.

Drain down: movement of effluent out of a lateral by infiltration into the soil treatment area

following a dosing event.


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Drainfield: see soil treatment area. Drainfield: consists of long underground perforated pipes

or tiles connected to a septic tank. The network of pipes is laid in gravel-filled trenches (2-3 feet

wide), or beds (over 3 feet wide) in the soil. Liquid waste or effluent flows out of the tank and is

evenly distributed into the soil through the piping system. The soil below the drainfield provides

the final treatment and disposal of a septic tank effluent. After the effluent has passed into the

soil, most of it percolates downward and outward, eventually entering the groundwater. A small

percentage is taken up by plants through their roots, or evaporates from the soil.

Drainline: 1. regarding collection of soil water to reduce saturation; see drain tile; 2. regarding

collection of effluent in the bottom of a media filter, see underdrain.

Drain tile: terracotta or perforated plastic pipe or other conduit that is used as part of a drainage

system.

Drain valve: see valve, drain.

Draught proofing: A way to stop heat from escaping a home, for example by sealing window

frames and using draught excluders under doors.

Drawdown: drop in the liquid level of a tank as a result of some phase of operation.

Drawdown test: measurement of the drop in liquid level in a dosing tank measured over time to

calculate dosing/delivery rate; may be expressed as a pump delivery rate (PDR) or siphon

delivery rate.

Drip emitter: drip distribution device that dispenses effluent to the infiltrative surface at a

predictable rate; see also emitter, non-pressure compensating and emitter, pressure

compensating.

Drip field: above or below grade soil treatment area where final treatment and dispersal occurs

via application of effluent to the infiltrative surface via pressurized drip tubing utilizing emitters;

see also drip field, surface; drip field, subsurface; and drip tubing.

Drip field, subsurface: drip field designed and installed such that the drip tubing is located at

least 6 below finished grade of native soil.

Drip field, surface: drip field designed and installed such that the drip tubing is located at the

finished grade of the soil surface.

Drip tubing: small diameter flexible plastic tubing manufactured with emitters uniformly spaced

along its length; see also drip emitter.


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Drip irrigation: system that is designed to meet the needs of the receiving vegetation using drip

distribution technology.

Drip lateral: length of drip tubing extending from the supply manifold to the return manifold.

Drip line: see drip tubing.

Drip zone: component of a drip distribution system made up of a group of drip laterals that is

managed as a single unit.

Dripper loading: see loading rate, instantaneous.

Drop box: (i) device used for serial or sequential distribution of effluent by gravity flow to a

lateral of a final treatment and dispersal component; addition of such a device adds a means ofsystem management; (ii) device used to lower pipe elevation.

Dry soil: soil that does not exhibit visible signs of moisture content.

Drywell: partially lined underground pit (regardless of geometry) into which drainage from

roofs, basement floors or other such sources is discharged and from which the liquid seeps into

the surrounding soil; if effluent (such as that from a septic tank) is discharged to such a

component, it is considered a seepage pit.

Dual fields: see alternating drainfields.

Dumping: Disposing of waste illegally by not using bins or official recycling centres, civic

amenity sites or landfills.

Duplex system: control that operates two usually identical devices in a system (e.g., a duplex

pump system).

Dust: solid particles about 1-10m in size.

Dwelling: structure or building, or any portion thereof which is used, intended, or designed to beoccupied for temporary or permanent human living purposes including, but not limited to:

houses, houseboats, mobile homes, motor homes, travel trailers, hotels, motels, and apartments.

Dynamic head: see head, dynamic.


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E

Easement - A right, such as a right-of-way, afforded a person to make limited use of another's

real property.

Ecological Engineering: The design, management or reconstruction of sustainable ecosystems

that serve human needs such as providing clean water and food while requiring low energy

inputs. Ecological engineering has enhanced our understanding of environmental problems such

as wastewater treatment, wetlands damage and mitigation, the effect of nonpoint pollution on

ecosystems and ecosystem restoration.

Ecosystem:(i) An interactive system that includes the organisms of a natural communitytogether with their abiotic, physical, chemical and geochemical environment. (ii) A community

of organisms that depend on each other and the environment they inhabit.

Ecotourism: Small-scale tourism in fragile and protected areas that aims to have a low impact

on the environment, benefit local communities and enable tourists to learn more about the natural

and cultural history of the place. See also sustainable tourism.

Effective capacity: see tank capacity.

Effective depth: depth of liquid below the head space in a tank; see also head space; andoperating level.

Effective rainfall: amount of precipitation that infiltrates and is held in surface storage.

Effective size: in a sieve analysis, the particle diameter of which 10 percent of the sample is

finer by weight; also known as D10.

Effluent: (i) Waste material discharged into the environment, treated or untreated. Generally,

the term refers to liquid waste/wastewater. (ii) Liquid flowing out of a component or device. (ii)Liquid wastes such as sewage and liquid waste from industries.

Effluent filter: see effluent screen.


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Effluent screen: removable, cleanable (or disposable) device installed on the outlet piping of a

septic tank for the purpose of retaining solids larger than a specific size and/or modulating

effluent flow rate.

Effluent quality: physical, biological, and chemical characteristics of a liquid flowing from a

component or device.

Elapsed time meter (ETM): see meter, elapsed time.

Electric vehicle: A vehicle that is driven by an electric motor or battery and is generally less

noisy and less polluting than common combustion engine vehicles

Electrokinetic decontamination: a method of removing metals and other inorganic pollutants

from contaminated soils using electrodes.

Electrolysis: a chemical change brought about by the passage of an electric current through a

liquid; used in plating of metals, oxidation of cyanide.

Electronic Water Disinfection: a method of sterilising water by introduction of precise amounts

of copper and silver; suitable for cooling towers (Legionella control), potable water, swimming

pool and effluents.

Electrostatic precipitator: equipment in which particles in gas streams are passed through

ionisers and become charged, facilitating their subsequent removal.

Elevation: (i) height above a given level, such as sea level; (ii) high place or position; (iii)

drawing or diagram made by projection on a vertical plane; a flat drawing of the front, side, or

back of a building.

Elevation head: see head, elevation.

Emissions: In the context of the atmosphere, gases or particles released into the air that can

contribute to global warming or poor air quality.

Emission factor: Refers to a particular source of emissions and is generally expressed as thequantity of gas released into the atmosphere per unit of activity. An activity can refer to travel

distances for motor vehicles sources (or, alternatively, fuel consumption), or to a production

level for an industry. Emissions from a source are computed as the product of its activity level

and the corresponding emission factor.


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Emissions or discharges to water: Emissions to water include all discharges of biodegradable

substances or other substances soluble in water; discharges mixing with the water or influencing

the biophysical or chemical quality of the water. Heavy metals and hazardous wastes are

included, together with oily wastes, floating debris, silt, and other suspended matter.

Emitter, non-pressure compensating (non-PC): emitter that discharges effluent at rates

dependent upon operating pressure.

Emitter, pressure compensating (PC): emitter designed to deliver effluent at a consistent flow

rate under a range of op

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Microsoft Word - Wastewater Dictionary 07-04-2010