مسرد بيئي D

المعجم البيئي مشروع قيد العمل يحتاج ترجمة وغضافة بنود

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D Tech™ Environmental .eld test kits by Strategic Diagnostics, Inc.
D/DBP Disinfectant/disinfection by product.
D/DBP Rule (D/DBPR) Proposed U.S. EPA rule to limit the maximum contaminant level of trihalomethanes.
D/T level The dilution-to-threshold level of a water sample which indicates the number of dilutions of clean, odor-free air necessary to reduce an odor to a level that most people cannot detect.
D-20 Filter underdrain nozzle by In.lco Degremont, Inc.
Dac Floc Polyelectrolyte used to enhance liquid/solid separation by Dacar Chemical Co.
DAF See “dissolved air .otation (DAF).”
DAFT Dissolved air .oatation thickener.
daily cover Cover material spread and compacted on the top and side slopes of compacted solid waste at the end of each day to control .re, moisture, and erosion and to assure an aesthetic appearance.
Dakota Belt .lter press by HydroCal, Inc.
DALR Dry adiabatic lapse rate. See “adiabatic lapse rate.”
dalton A nominal unit of weight equal to that of a single hydrogen atom; 1 × 10–24 grams.
Dalton’s Law of Partial Pressure In a mixture of gases, each gas exerts pressure independently of the others and the pressure of each gas is proportional to the amount of that gas in the mixture.
Dangler Fine bubble aeration system by MixAir Technologies, Inc.
darcy A unit of measure used to indicate permeability, standardized by the American Petroleum Institute.
DataGator™ Sewer .ow metering system by TN Technologies, Inc.
DataRAM™ Continuous measurement airborne particulates monitor by MIE, Inc.
Davco Former name of USFilter/Davco.
Davis Process Former name of USFilter/Davis Process.
Davis Water & Waste Former name of USFilter/Davco.
Davis-D2 ™ Coarse bubble diffuser by USFilter/Davco.
Davis-OM™ Oval membrane air diffuser by USFilter/Davco.
Davy Bamag Former name of Lurgi Bamag GmbH.
day tank Tank used to store chemicals or diluted polymer solution for 24 hours or less.
dB See “decibel (dB).”
dBA See “A-scale sound level (dBA).”
DBC Plus® Bacterial culture for wastewater treatment by Enviro.ow Inc.
DBO Design-build-operate. A method of project implementation where a contractor is responsible for a facility’s design, construction, and long-term operation.
DBOO Design-build-own-operate. A method of project implementation where a contractor is responsible for a facility’s design, construction, ownership, and operation.

DBP See “disinfection byproduct (DBP).”
DBP0 Instantaneous disinfection byproduct concentration.
DBPFP See “disinfection byproduct formation potential (DBPFP).”
DBPP See “disinfection byproduct precursor (DBPP).”
DBS™ Clari.er and thickener drive units by DBS Manufacturing, Inc.
DC Direct current.
D-Chlor™ Dechlorination system using sodium sul.te tablets by Exceltec International Corp.
DCI System Six™ Open channel UV system by Bailey-Fischer & Porter.
DCP Dissolved concentration potential.
DCS See “distributed control system (DCS).”
DDT Dichlorodiphenyltrichloroethane. A chlorinated hydrocarbon insecticide banned in many countries because of its persistence in the environment and accumulation in the food chain.
DDW Distilled deionized water.
DE See “diatomaceous earth (DE).”
dead storage The stored reservoir water remaining at a level below the reservoir’s lowest discharge level, and therefore unavailable for use.
deadleg The part of a pipeline in which .uid does not .ow and may stagnate.
deaerator Device used to remove dissolved gases from solution.
dealkalization Any process that removes or reduces alkalinity of water.
dealkalizer Ion exchange unit with strong anion bed used to reduce bicarbonate alkalinity.
DeAmine™ Odor control product by NuTech Environmental Corp.
deashing See “demineralizing.”
decant Separation of a liquid from settled solids by pouring or drawing off the upper layer of liquid after the solids have settled.
decanter centrifuge See “solid bowl centrifuge.”
decarbonator A device used to remove alkalinity from solution by conversion to CO2 prior to air stripping.
decat water Water that has had the hardness minerals removed by a water softener.
decay products Degraded radioactive materials, often referred to as “daughters” or “progeny.”
DeCelerating Flo Gravity sand .lter by CBI Walker, Inc.
dechlorination The partial or complete reduction of residual chlorine by any chemical or physical process.
decibel (dB) The unit for measuring sound pressure levels. It is the logarithm of the ratio of the sound’s intensity to the intensity of the weakest audible sound.
declining-rate .ltration Filter operation where the rate of .ow through the .lter declines and the level of the liquid above the .lter bed rises throughout the length of the .lter run.
decontamination The process of reducing or eliminating the presence of harmful substances, such as infectious agents, so as to reduce the likelihood of disease transmission from those substances.
Dee Fo® Foam control additive by Ultra Additives, Inc.

deep bed .lter Granular media .lter with a sand or anthracite .lter bed that is deeper
than a conventional .lter, i.e., 0.9m (3 feet), and often up to 1.8m (6 feet) deep. Deep Bubble™ Corrosion control aeration system by Lowry Aeration Systems, Inc. Deep Draw Airlift diffuser for lagoons by Wil.ey Weber, Inc. deep well injection Technique where raw or treated wastes are discharged through
a properly designed well into a geological stratum. DeepAer Aeration system with rectangular eductor tubes by Walker Process Equipment. DeepBed Granular media .lter bed used as .xed .lm reactor by Tetra Process Technologies. De.ned Substrate Technology™ Reagent system designed to promote growth of target microbe by Environetics, Inc. De.ectofuser® Coarse bubble air diffuser by USFilter/Diffused Air Products
Group. de.occulating agent A material added to a suspension to prevent settling. defoliant A chemical applied to plants which causes them to lose their leaves. deforestation The permanent clearing of forest land and its conversion to nonforest
uses. degasi.er Device used to remove dissolved gases from solution, usually by means
of an air-stripping column. degradation The biological breakdown of organic substances. dehydrate The physical or chemical process where water in combination with
other matter is removed. DeHydro® Vacuum assisted sludge drying bed by In.lco Degremont, Inc. deinking The process of removing ink from secondary .bers. deionization (DI) The process of removing ions from water, most commonly
through an ion exchange process. dekSPRAY Cooling tower nozzles by Brentwood Industries, Inc. Delaval Filter Precoat condensate polishing .lter by Idreco USA, Ltd. deliquescent The ability of a dry solid to absorb water from the air and soften or
dissolve as a result. delist The use of a petition process to have a facility’s toxic designation rescinded. DelPAC Polyaluminum coagulants by Delta Chemical Corp. Delrin High molecular weight acetal resin polymer material by E.I. Dupont De
Nemours, Inc. Delt™ Traveling water screen chain by USFilter/Rex & Link-Belt Products. Delta™ Mixing technology by Calgon Carbon Corp. delta The .at alluvial area at the mouth of some rivers where an accumulation of
river sediment is deposited in a sea or lake. Delta G® Parallel plate separator by Smith & Loveless, Inc. delta P Differential pressure. delta T Differential temperature. DeltaFlow™ Water puri.cation plant by Ecolochem, Inc. Delta-Pak® Mass transfer packing media by Delta Cooling Towers, Inc. Deltapilot Hydrostatic level measurement device by Endress+Hauser.

Delta-Stak® Inclined plate clari.er by Baker Process.
Delumper® Solids disintegrator and crusher products by Franklin Miller, Inc.
demin Common abbreviation for “demineralizer.”
demineralizing The process of removing minerals from water, most commonly through an ion exchange process.
Demister® Mist eliminator by Koch-Otto York.
dendrimer Hyperbranch macromolecule to control inorganic water constituents to prevent crystal formation.
Denite® Denitri.cation process using a granular media .xed .lm reactor bed by Tetra Process Technologies.
denitIR® Biological denitri.cation system by Baker Process.
denitri.cation Biological process in which nitrates are converted to nitrogen.
Denitri-Filt™ Biological denitri.cation .lter by USFilter/Davco.
Densadeg® Thickener-clari.er unit with lamella zone and sludge recirculation by In.lco Degremont, Inc.
Densator® High density solids contact clari.er with primary and secondary mixing zones by In.lco Degremont, Inc.
dense, nonaqueous phase liquid (DNAPL) A liquid that is immiscible in and denser than water.
density The ratio of the mass of an object to its volume.
density current A .ow of water through a larger body of water which retains its unmixed identity due to a difference in density.
Densludge Digestion system with primary thickening unit by GL&V/Dorr-Oliver, Inc.
Dentrol Sludge density controller by Walker Process Equipment.
Deox/2000® Dechlorination analyzer by USFilter/Wallace & Tiernan.
Deox® Oxygen and dissolved gas removal technology by Ecolochem, Inc.
deoxyribonucleic acid (DNA) The macromolecule that contains the hereditary material vital to reproduction.
De-Pac™ Disposal dewatering .lter by PacTec, Inc.
Department of Energy (DOE) U.S. federal agency responsible for research and development of energy technology.
Department of Transportation (DOT) U.S. federal agency responsible for regulating transport of hazardous and nonhazardous materials.
depletion curve In hydraulics, a graphical representation of water depletion from storage-stream channels, surface soil, and groundwater.
Deplution Wastewater treatment products by JDV Equipment Corp.
Depolox® Chlorine, pH, and .uoride analyzer USFilter/Wallace & Tiernan.
depth .ltration Filtration classi.cation for .lters where solids are removed within a granular media bed.
Depurator Induced air .otation unit by Baker Hughes Process Systems.
dermal Used or applied to the skin.
dermal exposure Contact between a chemical and the skin.
dermal toxicity The ability of a pesticide or toxic chemical to poison people or animals by contact with the skin. See “contact pesticide.”

DES A synthetic estrogen, diethylstilbestrol is used as a growth stimulant in food animals. Residues in meat are thought to be carcinogenic.
Desal™ Desalination equipment and systems product line by Osmonics Desal.
Desalator™ Reverse osmosis product line by USFilter/Bekox.
desalination The process of removing dissolved salts from water.
Desalination Systems Former name of Osmonics Desal.
desalinization See “desalination.”
desalting See “desalination.”
DeSander® Hydrocyclone separator by Krebs Engineers.
desert A region characterized by a climatic pattern where evaporation exceeds precipitation.
deserti.cation The process where the biological productivity of land is reduced, resulting in desert-like conditions.
desiccant A substance capable of absorbing moisture, used as a drying agent.
design criteria (1) Engineering guidelines specifying construction details and materials. (2) Objectives, results, or limits that must be met by a facility, structure, or process in performance of its intended functions.
design storm The magnitude of a storm upon which the design of a storm water facility is based, usually expressed in terms of the probability of the occurrence over a period of years.
designated pollutant Air pollutants including acid mist, total reduced sulfur, and .uorides which are neither criteria nor hazardous pollutants, as described in the Clean Air Act, but for which new source performance standards exist.
designated uses Those water uses, including cold water .sheries, public water supply, and irrigation, identi.ed in state water quality standards that must be achieved and maintained as required under the Clean Water Act.
designer bugs Common term for microbes developed through biotechnology that can degrade speci.c toxic chemicals at their source in toxic waste dumps or in groundwater.
desilting basin A settling basin used for sedimentation of silt, usually for storm-water .ows.
desorption The release of an adsorbed solute from an adsorbent.
destination facility The facility to which regulated medical waste is shipped for treatment and destruction, incineration, and/or disposal.
destrati.cation Vertical mixing within a lake or reservoir to totally or partially eliminate separate layers of temperature, plant, or animal life.
destroyed medical waste Regulated medical waste that has been ruined, torn apart, or mutilated through thermal treatment, melting, shredding, grinding, tearing, or breaking so that it is no longer generally recognized as medical waste, but has not yet been treated.
destruction and removal ef.ciency (DRE) An expression of hazardous waste incinerator ef.ciency stated as the percentage of incoming principal organic hazardous components destroyed during incineration.
Destrux® Heavy duty rotary knife cutter to granulate scrap material by Franklin Miller, Inc.

desulfurization Removal of sulfur from fossil fuels to reduce pollution.
detectable leak rate The smallest leak from a storage tank expressed in terms of gallons-or liters-per-hour that a test can reliably discern with a certain probability of detection or false alarm.
detention time The theoretical time required to displace the contents of a tank or unit at a given rate of discharge.
detergent Synthetic washing agent that helps to remove dirt and oil and may contain compounds which kill useful bacteria and encourage algae growth when present in wastewater that reaches receiving waters.
detoxi.cation Treatment to remove a toxic material.
Detritor Grit removal unit with reciprocating raking mechanism by GL&V/Dorr-Oliver, Inc.
detritus (1) Decaying organic matter such as root hairs, stems, and leaves usually found on the bottom of a water body. (2) Grit or fragments of rock or minerals.
detritus tank Square tank grit chamber incorporating a revolving rake to scrape settled grit to a sump for removal.
Developure Depth .lter by Osmonics, Inc.
dew Water droplets that form on cool surfaces following condensation of atmospheric water vapor.
dew point The temperature to which air with a given concentration of water vapor must be cooled to result in condensation of the vapor.
Dewa Water and wastewater treatment systems by DWT-Engineering Oy.
dewater (1) To extract a portion of the water present in a sludge or slurry. (2) To drain or remove water from an enclosure.
dewatered sludge The solids remaining after the free water has been removed from a wet sludge.
dewatering lagoon A lagoon constructed with a sand and underdrain bottom.
dewatering table See “belt thickener.”
Dewplan Former name of USFilter/Dewplan.
DF Dilution factor.
DFR Dynamic .xed .lm reactor by Schreiber Corp.
DFT See “dry .lm thickness (DFT).”
DFT Classic® Wound .ber .lter cartridge by USFilter/Filtration & Separation.
DGF Dissolved gas .otation. See “dissolved air .otation (DAF).”
DHC See “dirt holding capacity (DHC).”
DHHS Department of Health and Human Services.
DI See “deionization.”
dialysis The separation of substances from solution on the basis of molecular size by diffusion through a semipermeable membrane.
Diamite Series™ Membrane-cleaning liquids for removal of organic and inorganic foulants by King Lee Technologies.
Diamond Gate Screenings press by Andritz-Ruthner, Inc. (Western Hemisphere) and USFilter/Contra-Shear.
Diamond Seal™ Metering gate by Tetra Process Technologies.
diarrhea Frequent and excessive discharging of the bowels, producing abnormally thin, watery feces, usually a symptom of gastrointestinal upset or infection.

diatom A unicellular algae with a yellowish brown color and siliceous shell.
diatomaceous earth (DE) Skeletal deposits of diatoms used as .lter aids and a .lter medium.
diatomaceous earth .lter Water treatment .lter that uses a layer of diatomaceous earth as the .lter medium.
diatomite See “diatomaceous earth.”
diazinon A common organophosphate insecticide.
dibenzofurans A group of highly toxic organic compounds.
DIC Dissolved inorganic carbon.
dieldrin A chlorinated hydrocarbon pesticide formerly used for moth-proo.ng and agricultural insect control, now banned in the U.S.
dielectric heater A solid waste treatment heating system where an alternating electric .eld of high frequency is used to generate heat in nonconductive or dielectric materials.
Diemme Membrane type .lter press by Olds Filtration Engineering, Inc.
Diffusadome® Coarse bubble air diffuser by Amwell, Inc.
Diffusair Carbon dioxide diffuser system by Walker Process Equipment.
diffused aeration The introduction of compressed air into water by means of submerged diffusers or nozzles.
diffuser A porous plate or tube through which air, or another gas, is forced and divided into bubbles for diffusion in liquids.
Diffuserator Carbon dioxide diffusion system by Walker Process Equipment.
diffusion The movement of suspended or dissolved particles from a more concentrated to a less concentrated area.
diffusion dialysis An ion exchange membrane process that separates ionic, nonionic or colloidal species from solution based on differing diffusion rates, using concentration differentials across the membrane as the driving force.
diffusive air test A high resolution test for detecting membrane integrity that measures the amount of air diffused through a wetted membrane.
Digesdahl Digestion apparatus for lab sample preparation for crude protein and mineral analysis by Hach Co.
digester A tank or vessel used for sludge digestion.
digestion The biological oxidation of organic matter in sludge resulting in stabilization.
Digichem Programmable titration analyzer by Ionics, Inc.
Digi-Flo® Flow rate meter and totalizer by Blue-White Industries.
Dijbo Hydraulically operated trash rake by Landustrie Sneek BV.
dike An embankment or ridge of materials used to prevent the movement of liquid or sludges.
dilatant Property of a liquid whose viscosity increases as agitation is increased.
diluent Any liquid, solid, or gaseous material used for diluting or dissolving.
dilution (1) Lowering the concentration of a solution by adding more solvent.
(2) The engineered mixing of discharged water with receiving water to lessen
its immediate aesthetic and/or biochemical impact. dilution factor See “dilution ratio.”

dilution ratio (1) The volumetric ratio of solvent to solute. (2) The ratio of the water volume in a stream to the waste volume introduced into the stream. The dilution ratio gives an indication of the capacity of a water body to assimilate a waste.
dimitic Lakes and reservoirs that freeze over and normally go through two strat
i.cation and mixing cycles a year. Dimminutor® Open channel comminutor by Franklin Miller, Inc. DIN Deutsche Industrie Normal. dinocap A fungicide used primarily by apple growers to control summer diseases. dinoseb A herbicide, also used as a fungicide and insecticide, that was banned by
the EPA because it posed the risk of birth defects and sterility. dioxin An aromatic halogenated hydrocarbon that is one of the most toxic com
pounds known. Dioxytrol Centrifugal oxygenation system by Hazleton Environmental, Inc. DIP® Dynamic inclined plane industrial skimmer by JBF Environmental Technology. Dipair™ Static tube aerator by In.lco Degremont, Inc. Diphonix™ Ion exchange resins by Eichrom Industries, Inc. Di-Prime™ Automatic trash pump by Goodwin Pumps of America. direct discharger A municipal or industrial facility which introduces pollution
through a de.ned conveyance or system such as outlet pipes; a point source. direct .ltration Filtration process that does not include .occulation or sedimentation pretreatment. direct reuse The bene.cial use of reclaimed water with transfer from a reclama
tion plant to the reuse site. Director™ Floating .ow diversion baf.e by Environetics, Inc. DirecTube Eductor tube anaerobic gas mixing unit by Walker Process Equipment. dirt holding capacity (DHC) The amount of contaminant fed to a .lter on a
weight basis that attains the .lter’s terminal differential pressure. disc screen A screening device consisting of a circular disc .tted with wire mesh
which rotates on a horizontal axis. Discfuser® Coarse bubble air diffuser by USFilter/Diffused Air Products Group. discharge The release of any pollutant, by any means, to the environment. Discor Disc dryer by Andritz-Ruthner, Inc. Discostrainer Fine screening device by Waterlink Separations, Inc. Discotherm Thermal sludge processor by LIST, Inc. Disc-Pak Cartridge .lter by Alsop Engineering Co. Discreen® Rotating disc screening device by Mono.o. discrete particle settling Phenomenon referring to sedimentation of particles in
a suspension of low solids concentration. Also called “type I settling.” Disc-Tube™ Membrane .ltration system by Rochem Environmental, Inc. Di-sep® Filtration systems by Smith & Loveless, Inc. disinfectant A substance used for disinfection and in which disinfection has been
accomplished.
disinfectant contact time The travel time, in minutes, for water to move from the point of disinfectant application to a point where the “residual disinfectant concentration” is measured. See also “C × T.”

disinfection The selective destruction of disease-causing microbes through the application of chemicals or energy.
disinfection byproduct (DBP) A byproduct which occurs or is anticipated to occur from the addition of commonly used water treatment disinfectants including chlorine, chloramine, chlorine dioxide, and ozone.
disinfection byproduct formation potential (DBPFP) An indirect measure of the amount of disinfection byproduct precursors in a sample.
disinfection byproduct precursor (DBPP) A substance that can be converted into a disinfection byproduct during disinfection.
dispersant An additive that prevents agglomeration of particulates or is used to break up concentrations of organic matter, such as oil spills.
dispersed suspended solids (DSS) The suspended solids remaining in a sample’s supernatant 30 minutes after settling.
dispersion model A mathematical representation of the transport and diffusion processes that occur in the atmosphere.
dispersion rate A diffusion parameter of gas plumes or stack ef.uents.
Disposable Waste Systems Former name of JWC Environmental.
Dispos-A-Filter™ Metals testing .lter capsule by Geotech/ORS Environmental Systems.
disposal The discharge, deposit, injection, dumping, spilling, leaking, or placing of any liquid or solid waste on land or water so that it may enter the environment or be emitted into the air.
Disposorbs Self-contained disposable adsorption systems by Calgon Carbon Corp.
dissociate The process of ionization of an electrolyte or salt when dissolved in water, forming cations and anions.
dissolved air .otation (DAF) The clari.cation of .occulated material by contact with minute bubbles causing the air/.oc mass to be buoyed to the surface, leaving behind a clari.ed water. Use of a gas other than air is referred to as “dissolved gas .otation” or “DGF.”
dissolved nitrogen .otation (DNF) A variation of the DAF process where nitrogen, rather than air, is used to assist in the removal of suspended solids.
dissolved organic carbon (DOC) The fraction of TOC that is dissolved in a water sample.
dissolved organic matter (DOM) The fraction of organic matter in water that passes through a 0.45 micron .lter.
dissolved oxygen (DO) The oxygen dissolved in a liquid.
dissolved solids Solids in solution that cannot be removed by .ltration with a
0.45 micron .lter. See “total dissolved solids (TDS).” distill See “distillation.” distillate A liquid product condensed from vapor during distillation. distillation The process of boiling a liquid solution followed by condensation of
the vapor for the purpose of separating the solute from the solution.
distributed control system (DCS) A collection of modules, each having a speci.c function, interconnected to carry out an integrated data acquisition and control operation.

distributor See “rotary distributor.”
diurnal (1) Occurring during a 24 hour period. (2) Happening during the day time, rather than the night time.
diurnal .uccation A daily .uctuation in .ow or compostion that is of a similar pattern from one 24 hour period to another.
diversion chamber A chamber used to divert all or part of a .ow to various outlets.
diversion dam A dam constructed to divert part of all of the water from a stream away from its main course.
diversity index A mathematical expression that depicts the diversity of a species in quantitative terms.
DLO™ Dynamic light obscuration technique used in a particle monitor by Chemtrac Systems, Inc.
DNA See “deoxyribonucleic acid (DNA).”
DNAPL See “dense, nonaqueous phase liquid (DNAPL).”
DNF See “dissolved nitrogen .otation (DNF).”
DNR Department of Natural Resources.
DO See “dissolved oxygen (DO).”
DOAS Differential Optical Absorption Spectrometry.
DOC See “dissolved organic carbon (DOC).”
doctor blade A scraping device used to remove or regulate the amount of material on a belt, roller, or other moving or rotating surface.
DOE See “Department of Energy (DOE).”
DOI U.S. Department of Interior.
Dokwed Back cleaned bar screen by USFilter/Hubert.
dolomite A natural mineral consisting of calcium carbonate and magnesium carbonate. Chemical formula is CaMg(CO3)2.
dolomitic lime Lime containing 30 to 50% magnesium oxide and 50 to 70% calcium oxide.
DOM See “dissolved organic matter (DOM).”
domestic wastewater Wastewater originating from sanitary conveniences in residential dwellings, of.ce buildings and institutions. Also called “sanitary wastewater” and “domestic sewage.”
domestic water use Water use within private homes.
Don-Press Screw-type solids/screenings press by Dontech, Inc.
DorrClone Grit classi.er unit by GL&V/Dorr-Oliver, Inc.
Dorrco Brand name of GL&V/Dorr-Oliver, Inc. products.
dosage A speci.c quantity of a substance applied to a unit quantity of liquid to obtain a desired effect.
dose equivalent A measure of effective radiation dose that considers differences in biological effectiveness due to the radiation type and its distribution in the body.
dose-response relationship The relationship between the dose of a pollutant and its effect on a biological system.
dosfolat® A folic acid micronutrient solution to improve wastewater settling marketed by Bioprime, Ltd.
dosimeter An instrument used for measuring radiation exposure.

dosing siphon A siphon that automatically discharges liquid onto a trickling .lter bed or other wastewater treatment device.
dosing tank A tank into which raw or partly treated wastewater is accumulated and held for subsequent discharge and treatment at a constant rate.
DOT See “Department of Transportation (DOT).”
Double Dish Pressure .lter underdrain by USFilter/Warren.
Double Ditch Oxidation ditch wastewater treatment process by USFilter/Krüger.
double salt Any salt containing two different cations or anions in a crystalline matrix.
DoubleGuard™ Bar screen bar rack with two sets of offset bars by USFilter/Headworks Products.
double-suction pump A centrifugal pump with suction pipes connected to the casing from both sides.
Dowex® Ion exchange resin by Dow Chemical Co.
downcomer A pipe directed downward.
downgradient The direction that groundwater .ows; similar to “downstream” for surface water.
downstream Toward the mouth of a stream or river in the direction of .ow.
dowsing The scienti.cally unproven practice of locating groundwater or buried objects by walking above the area while holding a branch, wooden stick, or metal rods and noting where it appears to be drawn downward to a particular spot. Also called “witching.”
DOX Dissolved organic halogen.
DP Differential pressure.
d-part® Waste conditioner by Medina Products Bioremediation Division.
DPD N,N-diethyl-p-phenylenediamine. An indicator which produces red gradations in the presence of chlorine residuals.
DPD-FAS DPD-ferrous ammonium sulfate method of measuring all species of chlorine residuals in a water or wastewater.
dracunculiasis A waterborne, parasitic disease caused by the Dracunculus medinensis worm, and the only known disease solely associated with unhealthy drinking water. Also called “guinea worm disease.”
draft tube A centrally located vertical tube used to promote mixing in a sludge digester or aeration basin.
Draft Tube Channel Oxidation ditch process formerly offered by Lightnin.
drag tank A rectangular sedimentation basin that uses a chain and .ight collector mechanism to remove dense solids.
Drag-Star™ Rectangular clari.er sludge removal device utilizing a cable drive and scraper carriage by Smith & Loveless, Inc.
Draimad™ Solids dewatering system by Waterlink/Aero-Mod Systems.
drain tile Short lengths of pipes laid in underground trenches to collect and carry away excess groundwater or to discharge wastewater into the ground.
drainage basin The area of land that drains water, sediment, and dissolved materials to a common outlet at some point along a stream channel.
drainage water Ground, surface, or stormwater collected by a drainage system and discharged into a natural waterway.

drainage well A well drilled to carry excess water off agricultural .elds. Because they act as a funnel from the surface to the groundwater below, drainage wells can contribute to groundwater contamination.
Drain-Dri® Wet pit pump by Yeomans Chicago Corp.
Drainpac™ Storm drain .ltration system by PacTec, Inc.
drawback The reverse .ow of water from the permeate side of a membrane to the feedwater or concentrate side as a result of osmosis.
drawdown (1) The drop in the water table or level of water in the ground when water is being pumped from a well. (2) The amount of water used from a tank or reservoir. (3) The drop in the water level of a tank or reservoir.
DRE See “destruction and removal ef.ciency.”
dredge To remove sediment or sludge from rivers or estuaries to maintain navigation channels.
dregs Small solid particles in a liquid that settle to the bottom of a container.
Dresser/Jeffrey Screening equipment product line acquired by Waste-Tech, Inc.
Drewcor® Corrosion inhibitor chemical additive by Ashland Chemical, Drew Industrial.
Drewgard Corrosion inhibitor by Ashland Chemical, Drew Division.
Drewpac® Coagulant used in water and wastewater treatment by Ashland Chemical, Drew Industrial.
Drexelbrook Former name of AMETEK Drexelbrook.
drift (1) Water lost from a cooling tower as mist or droplets entrain in the circulating air. (2) Pollutants entrained in a plant’s stack discharge.
drift barrier An arti.cial barrier designed to catch driftwood or other .oating material.
drift test A part of an emissions certi.cation process where the CEM must operate unattended for some period of time without the analyzers drifting out of calibration.
Driftor™ Drift eliminator by Kimre Inc.
drilling mud A .uid, often containing bentonite, used to cool and lubricate a drilling bit and remove cuttings from the bit and carry them to the well’s surface.
drinking water Water safe for human consumption or which may be used in the preparation of food or beverages, or for cleaning articles used in the preparation of food or beverages.
Drinking Water Contaminant Candidate List (DWCCL) A list of any chemical or microbial contaminant that is known or anticipated to occur in public water systems and which may be regulated in the future under the SDWA. The DWCCL replaces the Drinking Water Priorities List.
drinking water equivalent level (DWEL) The lifetime exposure level at which adverse health effects are not anticipated to occur, assuming 100% exposure from drinking water.
Drinking Water Priority List (DWPL) A 1988 list of drinking water contaminants which has been replaced by the “Drinking Water Contaminant Candidate List.”
drip irrigation A micro-irrigation water management technique used primarily for landscaping, where drips of water are emitted near the base of the plant.

drip proof Designation for motor enclosure with ventilating openings so that drops of liquids or solids falling on the motor will not enter the unit directly or by running along an inwardly inclined surface.
drought An extended period of dry weather which, as a minimum, can result in a partial crop failure or an inability to meet normal water demands.
drowned weir See “submerged weir.”
drum pulverizer A rotating cylinder used to shred solid waste by the intermingling action of internal baf.es acting on the wetted solid waste.
drum screen A cylindrical screening device used to remove .oatable and suspended solids from water or wastewater.
Drumm-Scale™ Drum weighing scale by Force Flow Equipment.
Drumshear Rotating .ne screen by Aer-O-Flo Environmental, Inc.
Drumstik Feed tube for drum mounted chemical feed system by USFilter/Stranco.
dry bulb temperature The air temperature measured by a conventional thermometer.
dry cleaning wastes Wastewater from laundry cleaning operations that use nonaqueous chemical solvents to clean fabrics.
dry .lm thickness (DFT) Thickness of a dried paint or coating usually expressed in mils.
dry ice Solidi.ed carbon dioxide frequently used as a refrigerant that vaporizes without passing through a liquid state.
dry weather .ow (DWF) The .ow of wastewater in a sanitary sewer during dry weather. The sum of wastewater and dry weather in.ltration.
dry well (1) A dry compartment in a pumping station where pumps are located.
(2) A well that produces no water. Dry-All Vacuum belt press by Baler Equipment Co. DryCal® Primary .ow calibration instrument by BIOS International Corp. drying bed See “sludge drying bed.” DSS See “dispersed suspended solids (DSS).” DST™ De.ned substrate technology. Reagent system designed to promote growth
of target microbes by Environetics, Inc.
dual .ow screen A traveling water screen arranged in a channel so that water enters through both the ascending and descending wire mesh panels and exits through the center of the screen.
dual media .lter Granular media .lter utilizing two types of .lter media, usually silica sand and anthracite.
Dualator® Gravity sand .lter by Tonka Equipment Co.
dual-phase extraction See “bioslurping.”
Dubl-Safe Measuring system for brine regeneration of softening unit by Culligan
International Corp. Duckbill® Wastewater sampler by Markland Specialty Engineering Ltd. duckweed See “Lemnaceae.” duct A tube or channel for gas or .uid .ow. dump A site used to dispose of solid waste without environmental controls. Dunkers Flow balancing system by Munters.

Duo-Clari.er Wastewater treatment clari.er formerly offered by GL&V/Dorr-
Oliver, Inc. Duo-Deck Floating cover for anaerobic digester tank by USFilter/Envirex. Duo-Filter Two-stage trickling .lter formerly offered by GL&V/Dorr-Oliver, Inc. Duo-Fine® Pleated media .lter cartridge by USFilter/Filtration & Separation. Duo-Flo Traveling mesh belt screen by Dontech, Inc. Duo-Pilot® Coagulant control system using pilot .lters by USFilter/Micro.oc. DuoReel Power cable reel system for clari.ers by Walker Process Equipment. DuoSparj Coarse bubble diffuser by Walker Process Equipment. DuoTherm® Biosolids production process by USFilter/Envirex. Duo-Vac Inclined screen unit by the former Bowser-Briggs Filtration Co. DuoVAL Automatically backwashed gravity sand .lter by General Filter Co. duplex pump A reciprocating pump having two side-by-side cylinders and con
nected to the same suction and discharge lines. duplex stainless steel A high strength stainless steel containing two forms of iron,
typically austenite and ferrite. Duplex™ Air scrubber with two modules by USFilter/Davis Process. Dupont® Brand name of E.I. DuPont De Nemours, Inc. Dura-Disc Fine bubble membrane diffuser by Wil.ey Weber, Inc. Dura-Fuser™ Aeration piping system by USFilter/Davco. Dura-Mix Mixer for aeration applications by Wil.ey Weber, Inc. Dura-Pac PVC sheet media by NSW Corp. Dura-Pleat™ Fabric dust collector .lters by Farr Co. Durasan™ Reverse osmosis protective sleeve by Osmonics Desal. Duratherm™ Reverse osmosis membranes for hot water sanitizing by Osmonics
Desal. Dura-Trac™ Sensor for streaming current transmitter by Chemtrac Systems, Inc. Durco Filtration equipment by Aqua Care Systems. Durex® Traveling water screen chain material by USFilter/Rex & Link-Belt Products. Duriron Former name of Aqua Care Systems. DuroFlow® Air blower by Gardner Denver Blower Division. Durotex® Dewatering belts by Industrial Fabrics Corp. Duroy Nonlubricated, metallic traveling water screen chain by USFilter/Rex &
Link-Belt Products. dust Fine-grained particles light enough to be suspended in air. dust mask Face mask designed to provide relief from irritation of the nose, mouth,
and throat caused by nontoxic dusts; not designed to be used when dust concentrations are greater than the PEL. Also called “nuisance mask.” dustfall jar An open container used to collect large particles from the air for
measurement and analysis. Dustube® Fabric .lter by Wheelabrator Air Pollution Control, Inc. DVB Divinylbenzene, the common crosslinking agent for making resin beads. DVGW German Association for Gas and Water Plants. DWCCL See “Drinking Water Contaminant Candidate List (DWCCL).” DWEL See “drinking water equivalent level (DWEL).” DWF See “dry weather .ow (DWF).”

DWI Drinking Water Inspectorate. Agency whose role is to enforce water qual-
ity/supply regulations for potable water which meets in England and Wales. DWPL See “Drinking Water Priority List (DWPL).” DWS Manufacturer of sewage grinders for JWC Environmental. Dynabeads® Anti-Cyrptosporidium by Dynal, Inc. DynaBlend™ Polymer blending and feeding system by Fluid Dynamics, Inc. DynaClear® Packaged water treatment system incorporating contact .ltration by
Parkson Corp. DynaCycle® Regenerative catalytic oxidizer by Monsanto Enviro-Chem Systems, Inc. DynaFloc Feedwell Clari.er feedwell design to promote mixing of .occulants by
GL&V/Dorr-Oliver, Inc. Dyna-Grind Screenings and sewage grinder formerly offered by USFilter/Head
works Products. Dynalloy® Filter cartridge with metal .ber media by USFilter/Filtration & Separation. dynamic head See “total dynamic head.” dynamic membrane A transient membrane formed on the surface of an estab
lished membrane by solids .ltered from the feed stream. Dynamic Probe™ Filter control system by Roberts Filter Group. Dynamic Systems Product group integrated within USFilter/Control Systems. DynaSand® Continuously backwashed moving bed sand .lter by Parkson Corp. Dynasieve™ Self-cleaning rotary .ne screen by Andritz-Ruthner, Inc. Dynatherm In-vessel composting system by Fair.eld Service Co. Dynatrol® Measurement level switches and liquid measurement devices by Auto
mation Products, Inc. DynaWave® Wet scrubbing system by Monsanto Enviro-Chem Systems, Inc. DynaZyme™ Odor control bio.lter system by Monsanto Enviro-Chem Systems, Inc. dyne A unit of measurement equal to the force that imparts an acceleration of
1 cm/s2 to a 1 gram mass. Dyneco Former bar screen manufacturer acquired by Parkson Corp. dysentery A disease of the gastrointestinal tract usually resulting from poor san
itary conditions and transmitted by contaminated food or water. Dystor Gas holder system for anaerobic digesters by USFilter/Envirex. dystrophic lakes Acidic, shallow bodies of water that contain humus and/or other
organic matter; contain many plants but few .sh. dystrophy A disorder caused by defective nutrition or metabolism.

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