مسرد بيئي S

المعجم البيئي مشروع قيد العمل يحتاج ترجمة وإضافات

A - B - C - D - E - F - G - H - I - J - K - L - M - N - O - P - Q - R - S - T - U - V - W - X - Y - Z

S&A Sampling and analysis.
S&L Smith & Loveless, Inc.
SAB See “Science Advisory Board (SAB).”
SAB Reactor Package wastewater treatment plant by Biosab, Inc.
SAC Starved air combustion.
SAC™ Sludge age control system by United Industries, Inc.
sacri.cial anode A sacri.cial piece of metal, usually zinc or magnesium, electrically connected to a more noble metal in an electrolyte. The anode goes into
solution at an accelerated rate to protect the more noble metal from corrosion.
SAE Society of Automotive Engineers.
safe Condition of exposure under which there is a practical certainty that no harm will result to exposed individuals.
Safe Drinking Water Act (SDWA) A U.S. Act assuring that public water supplies are free of contaminants which may cause health risks; it prevents endangerment of underground sources of drinking water.
safe water Water that does not contain harmful bacteria, toxic materials, or chemicals and is considered safe for drinking even though it may have taste, odor, color, and certain mineral problems.
safe yield The annual amount of water that can be taken from a source or supply over a period of years without depleting that source beyond its ability to be replenished naturally in “wet years.”
Safgard Rotary .ne screen products by Schlueter Co.
sag line See “inverted siphon.”
salination See “salinization.”
saline Containing or resembling sodium chloride or similar salts.
saline water See “salt water.”

salinity (1) The concentration of dissolved salts in water. (2) The total dissolved solids in water after all carbonates and organic matter have been oxidized.
salinization The accumulation of salts in a soil to the extent that plant growth is inhibited, usually occurring as a result of excessive irrigation in an arid area. Also spelled “salination.”
Salmonella An aerobic bacteria that is pathogenic in humans and chie.y associated with food poisoning.
Salmonellosis A common type of food poisoning characterized by a sudden onset of gastroenteritis caused by eating food contaminated with Salmonella bacteria.
salt A class of ionic compounds formed by the combination of an acid and a base, of which sodium chloride is one of the most common examples.
salt .ux The amount of dissolved substances that are able to pass through a reverse osmosis membrane.
salt marsh A coastal marsh periodically .ooded with salt water.
salt pan An accumulation or layer of salts in the soil that may be toxic to agricultural crops.
salt rejection In reverse osmosis, the ratio of salts removed to the original salt concentration.
salt splitting The conversion of salts to their corresponding acids or bases, usually by means of an ion exchange system.
salt water Water containing a dissolved salt concentration greater than 10,000 mg/L.
salt water intrusion The intrusion of salt water into a body of fresh surface water or groundwater.
salting out A procedure in which salt is added to a solution to cause an organic compound to precipitate so that it can be physically removed.
Salt-Master Water softener brine reclamation system by Culligan International Corp.
salvage The utilization of waste materials.
SAM™ Status alert modem to monitor disinfectant dosing system by Strantrol, Inc.
SAM™ Surge-anoxic mix wastewater treatment technology by Fluidyne Corp.
sampler A device used with or without .ow measurement to obtain a portion of water or waste for analytical purposes.
sampling well See “monitoring well.”
Sanborn Technologies Product line of Waterlink Biological Systems.
sanctions Actions taken by the federal government for failure to plan or implement a State Improvement Plan (SIP), and which may include withholding of highway funds and a ban on construction of new sources of potential pollution.
sand Any rock fragment between 1/16 mm and 2 mm in diameter.
Sand Dollar Sludge harvesting machine for sludge drying beds by Cherrington Corp.
sand drying bed See “sludge drying bed.”
sand .lter See “granular media .ltration.”
Sand.oat Combination dissolved air .oatation and sand .lter treatment system by Krofta Engineering Corp.
SandPIPER® Diaphragm pump by Warren Rupp, Inc.

Sandsep® Screw-type grit classi.er by Spirac.
Sandwash Hydrocyclone by Axsia Serck Baker, Inc.
SANE Sulfur and nitrogen emissions.
Sanilec® Sodium hypochlorite generating systems by Exceltec International Corp.
Sanilo™ Water treatment product line by USFilter Corp.
Sani-Sieve Gravity fed static screen by Dontech, Inc.
sanitary connection A single family residential connection or single commercial or industrial connection to a public water supply system.
sanitary land.ll See “land.ll (LF).”
sanitary sewer Collection system of underground piping used to remove sanitary wastewater.
sanitary sewer over.ow (SSO) Overloaded operating condition of a sanitary sewer that results from in.ow/in.ltration.
sanitary wastewater Domestic wastewater without storm and surface runoff that originates from sanitary conveniences.
San-I-Tech™ Grease interceptor by Scienco/FAST Systems.
Sanitron™ Ultraviolet water puri.er by Atlantic Ultraviolet Corp.
SanTech Product line of Waterlink Biological Systems.
Sanuril® Hypochlorite tablet disinfection system by Exceltec International Corp.
SAP Scienti.c Advisory Panel.
Saphyr® A sludge treatment process by USFilter.
saponify The conversion of a fat or grease into a soap by reaction with an alkali.
saprophytic bacteria Bacteria that feed on dead or nonliving organic matter.
SAR (1) See “sodium absorption ratio (SAR).” (2) See “supplied air respirator (SAR).”
SARA See “Superfund Amendments and Reauthorization Act.”
SASS Source assessment sampling system.
Satellite Electrically driven rotary distributor for .xed .lm reactor by Simon-Hartley, Ltd.
Sation® Water treatment product line by USFilter Corp.
saturated steam Vapor in equilibrium with water at the boiling temperature and containing no liquid.
saturated zone See “zone of saturation.”
saturation The maximum concentration of a phase or material that can be contained within another phase or another material.
Saturation Index See “Langelier Saturation Index (LSI).”
SAV Submerged aquatic vegetation.
SAV715 Stainless steel sludge collector chain by Hitachi Maxco, Ltd.
SavagePlate™ Molded .lter underdrain by Tetra Process Technologies.
savanna A tropical or subtropical grassland characterized by scattered trees. Also spelled “savannah.”
Save-All Clari.er designed for paper mill .ber recovery by Walker Process Equipment.
save-all Separation device used in a paper mill to reclaim .bers and .llers from white water.
SBA Strong-base anion exchanger.

SBC Submerged biological contactor.
SBOD Soluble BOD. See “biochemical oxygen demand (BOD).”
SBR See “sequencing batch reactor (SBR).”
SBS See “Sick Building Syndrome (SBS).”
SC™ Package spray-type deaerating heater by Graver Co.
SCADA Supervisory control and data acquisition. The hardware and software systems that gather and control data from a remote site.
SCADA-Flo™ Open channel transmitter by Marsh-McBirney, Inc.
scale A mineral deposit or precipitate that forms on the interior surface of containers or water lines as a result of a heating or other physical or chemical change.
Scalper™ Inclined conveyor screening belt by Derrick Corp.
scanning electron microscope (SEM) A microscope with a magni.cation range from 20X to 200,000X at a resolution of 100 ., where illumination is provided by a beam of electrons which scan the specimen surface.
ScanRDI™ Microbial detection system by Chemunex, Inc.
scarp A steep, almost perpendicular slope.
Scavenger Robotic scrubber and vacuum sludge removal system by Aqua Products, Inc.
scavenging (1) The unauthorized and/or uncontrolled removal of materials at any point in a solid waste management system. (2) The removal of a substance by converting it to another form or adsorbing it onto another compound.
SCBA Self-contained breathing apparatus.
SCC Source classi.cation code.
SCD See “streaming current detector (SCD).”
Scentoscreen Portable gas chromatograph for VOC analysis by Sentex Systems, Inc.
SCFM Standard cubic feet per minute.
Schistosoma A .atworm or blood .uke that is highly parasitic to snails during one phase of its life and to humans during another.
schistosomiasis A waterborne disease of tropical and subtropical regions transmitted to humans who wade or bathe in water infested by Schistosoma, with freshwater snails acting as intermediate hosts.
schmutzdecke A biologically active layer that forms on the top of slow sand .lters to aid in the removal of suspended solids.
Schoop Process Process for coating steel that uses a blast of air to spray a mist of molten metal onto the surface to be protected.
SchreiberFlex® Fine bubble diffuser by Schreiber Corp.
Schumacher Filters Former name of USFilter/Schumacher.
Science Advisory Board (SAB) A group of external scientists who advise the EPA on science and policy.
scienti.c method An orderly method of obtaining, organizing, and applying new knowledge.
Scion® Short cycle ion exchange system by USFilter/Rockford.
Scoop-A-Fish Traveling water screen .sh collection trough by Norair Engineering Corp.
ScorGuard® Organic cooling tower water treatment additive by Ecolab Inc.

Scorpion® Ultraviolet light disinfection system by Capital Controls Co.
scouring velocity The minimum velocity required to carry away material accumulations in a conduit or pipeline.
Scour-Pak® Granular media gravity depth .lter by Graver Co.
SCOVOx™ Catalyst/adsorber technology for VOC emissions destruction by Goal Line Environmental Technologies.
SCR (1) See “selective catalytic reduction (SCR).” (2) Silicon controlled recti.er.
scrap Materials discarded from manufacturing operations that may be suitable for reprocessing.
screening (1) A treatment process using a device with uniform openings to retain coarse solids. (2) A preliminary test method used to separate according to common characteristics.
screenings The material removed by a screening device.
screenings press A mechanical press used to compact and/or dewater material removed from mechanical screening equipment.
Screenings Washer Monster™ Washer/grinder for wastewater screenings by JWC Environmental.
Screezer Combination screening and dewatering device by Waste-Tech, Inc.
screw conveyor A conveyor utilizing a helical screw rotating within a trough to convey material.
screw pump A low lift, high capacity pump that raises water by means of a slowly rotating inclined shaft .tted with a helical blade which revolves in a trough or pipe. Also known as “Archimedes’ screw pump.”
Screwpeller™ Centrifugal screw impeller used in a surface aerator by Aeration Industries, Inc.
scroll centrifuge See “solid bowl centrifuge.”
scrubber A device used to removal particulates or pollutant gases from combustion or chemical process exhaust streams.
scrubbing The removal of impurities from an air or gas stream by entraining the pollutants in a water spray.
ScruPac™ Screw-typed screenings compactor by Vulcan Industries, Inc.
Scru-Peller® Sludge pump by Yeomans Chicago Corp.
SCSA Soil Conservation Society of America.
SCUBA™ Filter underdrain by USFilter/General Filter.
SCUBA™ Self-contained gate and valve actuator by Rodney Hunt Co.
scum Floatable materials found on the surface of primary and secondary settling tanks consisting of food wastes, grease, fats, paper, foam, and similar matter.
scum breaker A device installed in a sludge digester to break up scum.
scum collector A mechanical device for removing scum from the surface of a settling tank.
Scum Sucker™ Telescopic pipe for scum removal by United Industries, Inc.
scum trough A trough used in a primary sedimentation basin to remove scum and convey it from the basin.
Scumbuster™ Pump used to chop solids in a digester scum blanket by Vaughan Co., Inc.

SCWO See “supercritical water oxidation (SCWO).”
SDI Strategic Diagnostics, Inc.
SDI See “Silt Density Index (SDI).”
SDWA See “Safe Drinking Water Act (SDWA).”
sea A large body of salt water that is wholly or partly enclosed by land.
Sea Cell In-situ sodium hypochlorite generator by Baker Hughes Process Systems.
Sea Devil Floating oil skimmer by Vikoma International Ltd.
sea lettuce Common seaweed that can grow in nuisance concentrations in the presence of excess nutrients.
sea level The average surface level of the sea, unin.uenced by tidal movement or waves, used as a reference for elevation.
Sea Screen Seawater .ltration system by Baker Hughes Process Systems.
Sealtrode Sealed pump controller by Yeomans Chicago Corp.
Seaskimmer Floating oil skimmer by Vikoma International Ltd.
seawall A wall built to protect a coastline from erosion, and caused by wave action.
seawater General term for sea or ocean water, with a typical total dissolved solids concentration of 35,000 mg/L.
Secchi disk A small disk, divided into black and white quadrants, that is lowered into water to visually observe water clarity and estimate the depth of the euphotic zone.
Secchi disk depth The water depth at which a Secchi disk is no longer visible. In a lake, this depth is approximately equal to the euphotic zone.
Secodyne Product group of Polydyne, Inc.
second order reaction A reaction in which the rate of change is proportional to the square of the concentration of one of the reactants or to the product of the concentrations of two different reactants.
second stage biochemical oxygen demand See “nitrogenous oxygen demand (NOD).”
secondary clari.er A clari.er following a secondary treatment process designed for gravity removal of suspended matter.
secondary contaminant A contaminant that affects drinking water taste, odor, or aesthetics.
secondary drinking water regulations Nonenforceable regulations applying to public water systems and specifying the maximum contamination levels that, in the judgment of the EPA, are required to protect the public welfare, and which apply to any contaminants that may adversely affect the odor o.
secondary ef.uent Treated wastewater leaving a secondary treatment facility, usually having a BOD5 and suspended solids of less than 30 mg/L.
secondary emissions Emissions that occur as a result of the construction or operation of a facility but do not come from the facility.
secondary materials Materials that have been manufactured and used at least once and are to be used again.
secondary maximum contaminant levels (SMCLs) Guidelines that address taste, odor, color, and other aesthetic aspects of drinking water but do not present health risks.

secondary pollutant A pollutant formed in the environment as the result of a chemical reaction of two or more primary pollutants or naturally occurring elements.
secondary sludge The sludge from the secondary clari.er in a wastewater treatment plant.
secondary standards National ambient air quality standards designed to protect welfare, including effects on soils, water, crops, vegetation, manmade materials, animals, wildlife, weather, visibility, and climate.
secondary treatment The treatment of wastewater through biological oxidation after primary treatment.
second-stage BOD See “nitrogenous biochemical oxygen demand (NBOD).”
secure land.ll Land.ll which segregates and isolates hazardous materials from contacting each other, the groundwater, or the atmosphere.
secure maximum contaminant level Maximum permissible level of a contaminant in water delivered to the free .owing outlet of the ultimate user, or of contamination resulting from corrosion of piping and plumbing caused by water quality.
Sedi.oat Water and wastewater treatment unit by Krofta Engineering Corp.
Sedi.otor® Dissolved air .otation unit by In.lco Degremont, Inc.
sediment The solid material that settles from a liquid.
sediment yield The quantity of sediment arriving at a speci.c location.
sedimentation The removal of settleable suspended solids from water or wastewater by gravity in a quiescent basin or clari.er.
sedimentation basin A quiescent tank used to remove suspended solids by gravity settling. Also called clari.ers or settling tanks, they are usually equipped with a motor driven rake mechanism to collect settled sludge and move it to a central discharge point.
SEE Schloss Engineered Equipment.
seed (1) Crystalline particles added to a supersaturated solution to induce precipitation. (2) Well-digested sludge used to seed a sludge digester.
seepage Percolation of water through the soil from unlined canals, ditches, laterals, watercourses, or water storage facilities.
seepage pit A covered excavation that receives septic tank ef.uent and permits its ef.uent to seep through the bottom and sides of the excavation.
seepage spring A spring occurring where the water table breaks the ground surface. Also called a “gravity spring.”
Seghers Pelletech® Indirect sludge dryer and pelletizing unit by Wheelabrator Water Technologies, Inc.
Seghodryer Indirect contact sludge dryer by Seghers Better Technology USA.
selective catalytic reduction (SCR) Flue gas treatment process for the removal of NOX by reduction with ammonia to form elemental nitrogen and water.
selective pesticide A chemical designed to affect only certain types of pests, leaving other plants and animals unharmed.
Selecto.lter Revolving drum screen strainer by USFilter/Diffused Air Products Group.

Selector Plug Flow™ Biological wastewater treatment process by USFilter/Indus
trial Wastewater Systems.
Selectostrainer In-line strainer formerly offered by USFilter/Headworks Products.
Selex® Graded density cartridge .lters by Osmonics, Inc.
self-sustaining The point at which a process provides suf.cient energy to operate
without the need for supplementary fuel.
SelRO® Membrane .ltration systems by LCI Corp.
SEM See “scanning electron microscope (SEM).”
semi-con.ned aquifer An aquifer partially con.ned by soil layers of low permeability through which recharge and discharge can still occur.
semipermeable A membrane that does not have measurable pores, but through which smaller molecules can pass.
senescence The aging process sometimes used to describe lakes or other bodies of water in advanced stages of eutrophication.
senescent lake A very old lake, practically full of sediment and rooted water plants, which will eventually become a marsh.
sensible heat Heat measurable by temperature alone.
Sension™ Water analyzer meter by Hach Co.
sensitivity The ability of a unit or instrument to respond to a small difference in
values.
Sentinel™ Filter backwash control system by Roberts Filter Group.
Sentre-Fier Rotary .ne screen by Dontech, Inc.
Sentry Groundwater gasoline recovery system by Douglas Engineering.
Sentry-II® VOC sampler by BIOS International Corp.
SEPA® Reverse osmosis membranes by Osmonics, Inc.
Separator-Plus™ Parallel plate separator by USFilter/Davco.
SepraEight® Deep bed condensate polisher by Graver Co.
sepralators Membrane elements.
septage The settled solids produced in individual on-site wastewater treatment systems including septic tanks and cesspools.
septic Condition characterized by bacterial decomposition under anaerobic conditions.
septic system An onsite system designed to treat and dispose of domestic wastewater typically consisting of a tank that receives waste from a residence or business and a system of tile lines or a pit for disposal of the sludge that remains after decomposition of the soluble organic matter.
septic tank A domestic wastewater treatment device principally used for individual residences that combines sedimentation, sludge digestion, and sludge storage in a single or dual compartmented tank. See also “septic system.”
septicity The condition that results from biological degradation of organic matter in wastewater under anaerobic conditions, usually producing hydrogen sul.de or other odorous compounds.
Septra™ Pleated backwash .lters by Pall Corp.
septum A permeable material used to support .lter medium.

sequencing batch reactor (SBR) Treatment process characterized by the interruption of .ow to the reactor during the sedimentation and decanting phase of treatment.
Sequest-All Sequestering agent used to control iron scaling and corrosion by Sper Chemical Corp.
sequestering agent A chemical compound such as EDTA that binds with other compounds or ions so they cannot be involved in chemical reactions. See also “chelating agent.”
sequestration The formation of a stable, water soluble complex with an ion in solution to prevent precipitation or scaling. See also “chelation.”
Sequox™ Biological wastewater treatment process for nutrient removal by Waterlink/Aero-Mod Systems.
Seral® Laboratory water treatment product line by USFilter/Lowell.
Serck Baker Former name of Axsia Serck Baker, Inc.
Ser-Ductor® Air-free agitation system by Ser.lco, Ltd.
Ser.lco® Wastewater treatment equipment products by Ser.lco, Ltd.
seroepidemiology The measuring of serum antibodies to speci.c pathogens in a population.
serogroup A group of closely related organisms having one or more common antigens.
Serpentix® Convoluted, self-cleaning belt conveyor by Serpentix Conveyor Corp.
service connector The pipe that carries tap water from a public water main to a building.
service factor (SF) A multiplier that when applied to the rated power indicates the permissible power loading that may be carried under the conditions speci.ed.
service line sample A one-liter sample of water collected according to federal regulations that has been standing for at least 6 hours in a service pipeline.
service pipe The pipeline extending from the water main to the building served or to the consumer’s system.
SES Secondary emissions standard.
Sessil® Polyethylene strip media for trickling .lters by NSW Corp.
SETLdek Clari.er tube settlers by Brentwood Industries, Inc.
setpoint An input value to be maintained by a control device.
settleability The tendency of suspended solids to settle.
settleable solids That portion of suspended solids which are of a suf.cient size and weight to settle to the bottom of an Imhoff cone in 1 hour.
settled sludge volume (SSV) Volume of settled sludge measured at predetermined time increments for use in process control calculations.
settling chamber A series of screens placed in the way of .ue gases to slow the stream of air, thus helping gravity to pull particles into a collection device.
settling tank A quiescent tank used to remove suspended solids by gravity settling. Also called clari.ers or sedimentation basins, they are usually equipped with a motor driven rake mechanism to collect settled sludge and move it to a central discharge point.
settling tubes See “tube settlers.”

settling velocity The rate at which a particle settles through air or water.
7Q10 An abbreviation for a design stream .ow rate describing the lowest stream .ow for 7 consecutive days that would be expected to occur once in 10 years. See also “xQy.”
sewage See “wastewater.”
sewage fungus Common term for .lamentous mass of fungi and bacteria resulting from high organic loadings that can clog or reduce ef.ciency of waste treatment equipment.
sewer Collection system of underground piping used to remove wastewater.
Sewer Chewer™ Comminuter/sludge grinder by Yeomans Chicago Corp.
sewer gas A gas mixture produced by anaerobic decomposition of organic matter usually containing high percentages of methane and hydrogen sul.de.
sewerage The entire system of wastewater collection, treatment, and disposal.
sewershed Land area that drains into a sewer.
SF See “service factor (SF).”
SFA Spectral .ame analyzer.
SFT™ Sediment .ushing tank by John Meunier, Inc.
ShallowTray Aeration system for removal of volatile organics by Northeast Environmental Products, Inc.
Shann-No-Corr Zinc metaphosphate corrosion inhibitor and sequestering agent by Shannon Chemical Corp.
Sharples® Division of Alfa Laval Separation, Inc.
sharps Hypodermic needles, pipettes, scalpel blades, blood vials, needles with attached tubing, broken or unbroken glass, and culture dishes used in animal or human patient care or treatment, or in medical, research, or industrial laboratories.
Sharpshooter Polymer feed and control system by Norchem Industries.
Shartles Product line by Thermal Black Clawson.
Shearfuser Cast iron diffuser for anaerobic digestion by USFilter/Diffused Air Products Group.
sheet .ow Overland stormwater .ow in a thin sheet of uniform thickness.
shell-and-tube heat exchanger A tubular heat exchanger housed within the shell of a pressure vessel.
sherardizing A process for protecting iron from corrosion by means of a corrosion resistant layer of zinc on the iron surface.
Shigella A bacterium associated with dysentery that is transmitted through consumption of water or food contaminated with fecal matter.
shigellosis A gastrointestinal disorder usually caused by food or waterborne organisms of the genus Shigella.
shock load A sudden hydraulic or organic load to a treatment plant.
shore (1) The land bordering a body of water. (2) To brace or give support.
short circuiting Uneven .ow through a vessel that results from density currents or inadequate mixing which allows some currents to leave the vessel more quickly than others.

short term exposure limit (STEL) The maximal allowable level of a material in workplace air, usually measured over a 15-minute period.
short ton See “ton.”
Shriver® Plate and frame .lter press by Baker Process.
shute The horizontal wire in woven wire mesh, also called the “weft” wire.
SHWL Seasonal high water level.
SI unit The international system of units (Système International) largely based on the metric system used for measuring length, mass, volume, and radiation.
SIC See “Standard Industrial Classi.cation (SIC).”
sick building syndrome (SBS) Condition in which at least 20% of a building’s occupants display symptoms of illness for more than 2 weeks and the source of the illness cannot be positively identi.ed.
side hill screen See “static screen.”
side water depth (SWD) The depth of water measured along a vertical interior wall of a basin or tank.
Side Winder Environmental screens by Cook Screen Technologies, Inc.
SideCar™ RBC aeration system by Jones MacCrea, Inc.
siderite A mineral of ferrous carbonate.
sidewall The wall at the side of a structure.
Sidewall Separator In-channel clari.er for an oxidation ditch by Lakeside Equipment Corp.
sieve analysis A size distribution analysis of a .lter sand sample using a series of standard sieve screens.
sieve size The standard sieve size through which a sample of sand will pass.
sievert Unit of radiation equal to the amount that produces the same damage to humans as 1 roentgen of high voltage X-rays.
SightWell Circular clari.er with hydraulic suction type sludge removal system by Walker Process Equipment.
Sigma Low speed surface aerator by Purestream, Inc.
Sigma Flight Fiberglass sludge collector .ight by USFilter/Envirex.
signal words The words used on a pesticide label — “Danger, Warning, Caution” — to indicate level of toxicity.
signi.cant deterioration Pollution resulting from a new source in previously “clean” areas. See “prevention of signi.cant deterioration (PSD).”
signi.cant municipal facilities Those publicly owned sewage treatment plants that discharge a million gallons per day or more and are therefore considered by states to have the potential to substantially affect the quality of receiving waters.
signi.cant violations Violations by point source dischargers of suf.cient magnitude or duration to be a regulatory priority.
SIHI Pumps Former name of Sterling Fluid Systems (USA).
SIHI-Halberg Digester draft tube sludge mixer by SIHI Pumps, Inc.
Silent Pump Portable sewage pumping station by Gorman-Rupp Co.
silica A mineral composed of silicon and oxygen.
silicate Any compound containing silicon, oxygen, and one or more metallic compounds.

siliceous Composed of or containing silica or a silicate compound.
siliceous gel zeolite A synthetic hydrated sodium aluminosilicate with ion exchange properties, once widely used in ion exchange water softeners. See also “gel zeolite.”
silicosis A lung disease caused by prolonged inhalation of silica dust which results in .brosis or scarring of lung tissue.
Sil-Kleer® Filter aid by Silbrico Corp.
silo A tall, cylindrical storage vessel for dry solids.
Silo Pac Chemical feed system by USFilter/Wallace & Tiernan.
Siloda™ High rate sludge composting process by USFilter/Krüger (North America) and OTV.
silt Individual mineral particles ranging in size between .ne sand and clay.
silt density index (SDI) A measure of the fouling tendency of water based on the timed .ow of a liquid through a membrane .lter at a constant pressure.
silting The deposition of silt or sediment in a waterbody.
silvaculture Forest management for the cultivation and harvest of timber.
Silver Band Granular media pressure .lter by Baker Hughes Process Systems.
Silver Series™ Membrane diffuser by Sanitaire Corp.
Silverback™ Aqueous cleaner recovery system using ceramic membrane .lters by USFilter/Industrial Wastewater Systems.
silviculture Management of forest land for timber.
Simcar® Turbine aerator by United Industries, Inc.
Simplex Low speed surface mechanical aerators by USFilter/Asdor.
Simplex™ Single module air scrubber by USFilter/Davis Process.
Sim-Pre™ Biological nutrient removal process for wastewater treatment by USFilter/Envirex.
Simrake Rotary bar screen by Simon-Hartley, Ltd.
Simspray Rectangular distributor for .xed .lm reactor by Simon-Hartley, Ltd.
Simultech™ Biological nutrient removal system by Schreiber Corp.
Simul-Wash™ Simultaneous air/water .lter backwash system by Tonka Equipment Co.
Sinclair Internally fed rotary .ne screen by Bielomatik London, Ltd.
sink Place in the environment where a compound or material collects.
sinking Controlling oil spills by using an agent to trap the oil and sink it to the bottom of the body of water where the agent and the oil are biodegraded.
sinter To bond and partly fuse masses of metal particles together through the use of heat below the melting point, without actually liquefying.
SIP See “State Implementation Plan (SIP).”
siphon A closed conduit, a portion of which lies above the hydraulic grade line, resulting in a pressure less than atmospheric and requiring a vacuum within the conduit to start .ow.
SITE See “Superfund Innovative Technology Evaluation (SITE).”
site assessment program A means of evaluating hazardous waste sites through preliminary assessments and site inspections to develop a Hazard Ranking System score.

Sitepro™ Remediation site control system by Geotech ORS Environmental Equipment.
siting The process of choosing a location for a facility.
SIU Signi.cant industrial user.
Siverseries™ Packaged desalination system by Matrix Desalination, Inc.
SK® Variable area .owmeter by McCrometer, Inc.
skid mounted Equipment or equipment packages mounted on a horizontal structure or platform to facilitate handling and/or installation.
Skim-Kleen® Oil removal belt skimmer by Tenco Hydro, Inc.
skimming The process of removing or diverting water and/or .oating matter from the surface of a liquid.
Skim-Pak™ Floating, self-adjusting weir skimmer by Douglas Engineering.
Skim-Pak™ Floating skimmer by ABS Pumps, Inc.
skip Bar screen cleaning rake.
SKRAM Acoustic .sh behavioral control device by USFilter/Rex & Link-Belt Products.
SL™ Granular media .lter underdrain by F.B. Leopold Co., Inc.
slag Waste residues produced by metal smelting and coal gasi.cation.
slake The process of mixing lime with water to accomplish a chemical combination.
slaked lime See “hydrated lime.”
slash and burn An agricultural practice where vegetation is cut, allowed to dry, and burned prior to soil cultivation and planting.
Slide Gate Screenings press by Andritz-Ruthner, Inc. (Western Hemisphere) and USFilter/Contra-Shear.
slime (1) Substances of a viscous organic nature, usually formed from a microbiological growth, which attach themselves to other objects, forming a coating.
(2) The coating of biomass that accumulates in trickling .lters or sand .lters
and periodically sloughs away to be collected in clari.ers.
Slinger® Sludge spreader by Knight Manufacturing Corp.
Slo-Mixer Axial .ow paddle .occulators by USFilter/Envirex.
slop oil Separator skimmings and tramp oil generated during re.nery startup, shutdown, or abnormal operation.
slough A swamp, bog, or marsh, especially if part of an inlet or backwater.
sloughing The disattachment of accumulated biological solids from trickling .lter media.
slow sand .lter Sand .lter characterized by low .ow rates relying on the formation of a layer of solids on the top of the sand bed to accomplish most of the .ltration.
sludge Accumulated and concentrated solids generated within the wastewater treatment process that have not undergone a stabilization process.
sludge age The average time microbial cell remains in an activated sludge system. It is equal to the mass of cells divided by the rate of cell wasting from the system.
Sludge Age Controller™ Sludge age control system by United Industries, Inc. sludge blanket The accumulated sludge hydrodynamically suspended in a clari.er or other enclosed body of water.

sludge bulking A phenomenon that occurs in activated sludge plants where a sludge does not readily settle or concentrate. sludge cake Dewatered residue from a .lter press, centrifuge, or other sludge dewatering device. sludge collector Mechanisms used in clari.ers to collect and remove settled solids
from the tank bottom. sludge conditioning See “conditioning.” Sludge Detention Optimizer™ Sludge thickening/conditioning process by Don-
tech, Inc. sludge dewatering The removal of a portion of the water contained in sludge by
means of a .lter press, centrifuge, or other mechanism. sludge digestion See “digestion.” sludge dryer A device utilizing heat for the removal of a large portion of water
within sludge.
sludge drying bed A partitioned area consisting of sand or other porous material upon which sludge is dewatered by drainage and evaporation. Also known as “drying bed” or “sand drying bed.”
Sludge Expert Automatic belt press control and management system by Alpine
Technology, Inc. Sludge Gun® Sludge level detector by Markland Specialty Engineering, Ltd. Sludge Guzzler Hydraulically driven sludge pump by Guzzler Manufacturing, Inc. Sludge Mate™ Container .lter by Flo Trend Systems, Inc. sludge stabilization A treatment process to convert sludge to a stable product for
ultimate disposal or use and reduce pathogens to produce a less odorous

product. Sludge Sucker™ Clari.er sludge removal device by USFilter/General Filter. sludge volume index (SVI) The volume in milliliters occupied by 1 gram of
settled sludge after settling for 30 minutes in a graduated cylinder. Sludgebuster™ Sewage shredder by ZMI/Portec Chemical Processing. SludgeCleaner® Sludge and scum screen and compactor by Parkson Corp. SludgeMaster® Sludge dryer by USFilter/Davis Process. SludgeMaster® Submersible air-powered pump by Warren Rupp, Inc. SludgeMIZER Sludge dryer by Fen-Tech Environmental, Inc. Sludgepactor Sludge screen and compactor by Waste-Tech, Inc. SludgePress™ Biosolids dewatering products by Enviroquip, Inc. Sludgi.er Lagoon dredge by VMI Inc. Sludglite® Sludge blanket level detector by Ecolotech Corp. slug load A sudden hydraulic or organic load to a treatment unit. sluice gate Manual or power-operated gate used to isolate a channel from .ow. slurry A suspension of a relatively insoluble chemical in water, usually having a
suspended solids concentration of 5000 mg/L or more. Slurrycup™ Grit removal system by Eutek Systems, Inc. Slurrystore® Slurry storage system by A.O. Smith Engineered Storage Products. small calorie (cal) See “calorie.” small quantity generator (SQG) A generator of between 100 and 1000 kg/month
of hazardous wastes. Sometimes called a “squeegee.”

small-quantity handlers (SQHs) Universal waste handlers who accumulate up to 5000 kilograms of wastes.
Smart Skimmer Oil removal system by Douglas Engineering.
SmartFilter™ Traveling bridge .lter by Agency Environmental, Inc.
SmartRO™ Reverse osmosis system by Water and Power Technologies.
SMBS Sodium metabisul.te.
SMCL Secondary maximum contaminant level.
SMCLs EPA-mandated maximum contaminant level in drinking water based on taste, odor, or aesthetics.
SMCRA See “Surface Mining Control and Reclamation Act (SMCRA).”
smelter A facility that melts or fuses ore, often with an accompanying chemical change, to separate its metal content.
SMOA Superfund Memorandum of Agreement.
smog A type of air pollution characterized by reduced visibility due to atmospheric particulates and elevated levels of photochemical oxidants.
Smogless™ Wastewater treatment and sludge drying and incineration plants by USFilter/Smogless.
smoke The suspended matter in an exhaust emission which obscures the transmission of light.
smoke number (SN) A dimensionless term quantifying smoke emissions.
Smooth-tex Rectangular woven mesh for screening equipment by USFilter/Rex & Link-Belt Products.
SMSA Standard metropolitan statistical area.
SMX Belt .lter press by Andritz-Ruthner, Inc.
SN See “smoke number (SN).”
SNAAQS Secondary National Ambient Air Quality Standards.
Snail Grit dewatering system by Eutek Systems, Inc.
SNARL Suggested no adverse response level.
SNC Signi.cant noncompliers.
Snow.ake Packing Plastic packing media for air stripping applications by Norton Co.
SO2 Sulfur dioxide.
SOC See “synthetic organic chemicals (SOC).”
SOCMA Synthetic Organic Chemical Manufacturers Association.
SOCMI Synthetic organic chemical manufacturing industry.
SOD Sediment oxygen demand.
soda ash See “sodium carbonate.”
sodium absorption ratio (SAR) An expression describing the relative activity of sodium ions in exchange reactions with soil.
sodium aluminate An auxiliary coagulant used in water treatment. Chemical formula is Na2Al2O4.
sodium bisul.te A liquid dechlorinating agent. Chemical formula is NaHSO3.
sodium carbonate A compound often used in water softening operations, also called “soda ash.” Chemical formula is Na2CO3.
sodium chloride The chemical name for common salt. Chemical formula is NaCl.

sodium cycle exchange Ion exchange water softening process in which sodium on the ion exchange resin is exchanged for hardness and other ions in water. Sodium chloride is commonly used as the regenerant.
sodium hexametaphosphate (NaHMP) An alkaline metallic element which is water soluble and commonly used as a sequestering or dispersing agent.
sodium hydroxide Caustic soda. Chemical formula is NaOH.
sodium hypochlorite A liquid chlorine solution frequently used as a water or wastewater disinfectant. Chemical formula is Na(OCl)2.
sodium metabisul.te A crystalline form of sulfur dioxide used to remove chlorine. Chemical formula is Na2S2O5.
sodium sul.te An oxygen scavenger used in boiler and cooling water systems. Chemical formula is Na2SO3.
sodium-free water Bottled water containing less than 5 milligrams of sodium per serving.
soft detergents Cleaning agents that break down in nature. See also “linear alkyl sulfonate (LAS).”
soft water Any water containing less than 17.1 mg/L (1 gpg) of calcium or magnesium expressed as calcium carbonate.
softening Treatment process that involves the removal of calcium and magnesium ions from water.
SOG Stripper off-gas.
soil The combination of mineral and organic matter that supports plant life on the surface of the earth.
soil adsorption .eld A sub-surface area containing a trench or bed with clean stones and a system of piping through which treated sewage may seep into the surrounding soil for further treatment and disposal.
soil conditioner An organic material like humus or compost that helps soil absorb water, build a bacterial community, and take up mineral nutrients.
soil erodibility A measure of the soil’s susceptibility to raindrop impact, runoff, and other erosional processes.
soil .ushing In-situ remediation technique where large volumes of water or other solutions are injected into the soil or groundwater to .ush hazardous contaminants to a recovery point.
soil gas Gaseous elements and compounds in the small spaces between particles of the earth and soil. Such gases can be moved or driven out under pressure.
soil horizon A zone or layer within a soil made distinctive by its color, texture, or mineral content.
soil sterilant A chemical that temporarily or permanently prevents the growth of all plants and animals depending on the chemical.
soil vapor extraction (SVE) Technique to remove VOCs and promote bioremediation of compounds in unsaturated soils.
Sokalan® Antiscalant for desalination of seawater by BASF.
sol Colloidal dispersion of solids in liquid.
solar constant The rate that the sun’s radiant energy is received per unit area on a horizontal surface at the top of the earth’s atmosphere.

solar pond Pond used to accomplish evaporation via direct solar heating.
solar still A distillation device that utilizes solar energy.
solder Metallic compound used to seal joints between pipes, and until recently, usually contained 50% lead. Use of lead solder containing more than 0.2% lead is now prohibited for pipes carrying drinking water.
sole-source aquifer An aquifer that supplies 50% or more of the drinking water of an area.
solid bowl centrifuge Continuous operation centrifuge consisting of a cylindrical, tapered bowl and an internal helical scroll, both revolving at slightly different speeds to separate solids from water by means of a centrifugal force. Also called “scroll centrifuge” or “decanter.”
solid waste Garbage, refuse, sludge, and other discarded material resulting from
community activities or commercial or industrial operations.
solid waste disposal The .nal placement of refuse that is not salvaged or recycled.
solid waste management Supervised handling of waste materials from their source through recovery processes to disposal.
Solidex Screw press system by Hosokawa Bepex Corp.
solidi.cation A process where materials are added to waste to produce a solid.
solidi.cation and stabilization Removal of wastewater from a waste or the chem
ical change that makes it less permeable and susceptible to transport by water.
solids balance A mathematical representation of a treatment system that de.nes the amount of solids entering and exiting each unit treatment process.
solids contact clari.er A clari.er in which liquid passes upward though a solids blanket and discharges at or near the surface.
solids retention time (SRT) The mass of solids in a vessel (kg) divided by the solids removed (L/d).
Solidur UHMW polyethylene components for chain and .ight sludge collectors by Solidur Plastics Co.
Soliquator Clari.cation unit by Orival, Inc.
Solo™ Controllerless downwell cleanup pumps by QED Environmental Systems, Inc.
Solu Comp® Water measurement instrument by Rosemount Analytical, Inc.
solubility The amount of a substance that can dissolve in a solution under a given set of conditions.
solubility product The equilibrium constant that describes the reaction by which a precipitate dissolves in pure water to form its constituent ions.
soluble Capable of being dissolved in a .uid.
solum The upper layers of soil including the top soil (A-horizon) and intermediate soil (B-horizon).
solute A substance dissolved in a .uid.
solution A liquid that contains dissolved solute.
Solvay Interox Product group of Solvay America.
Solvay Minerals Product group of Solvay America.
solvent Liquid capable of dissolving or dispersing one or more substances.

solvent extraction The process of selectively extracting a liquid constituent from a wastewater using an organic solvent. Also called “liquid-liquid extraction (LLE).”
Solvo-Salvager® Vacuum assisted distillation equipment by Westport Environmen
tal Systems. Som-A-System® Sludge thickening process by Somat Corp. sone A subjectively determined unit of the loudness of a sound. Sonix 100 Tank-mounted chlorinator by USFilter/Wallace & Tiernan. Sonozaire™ Electronic odor control device by Howe-Baker Engineers, Inc. soot Carbon dust formed by incomplete combustion. sorbent A solid material used to concentrate dissolved solids. Sorb-N-C™ Packaged stack gas sorbent by Church & Dwight Co. Inc. Sorbond® Sludge stabilizer by Colloid Environmental Technologies Co. sorption The concentration of dissolved solids through absorption or adsorption
on a solid. SOS Stormwater over.ow screens by John Meunier, Inc. SOTE Standard oxygen transfer ef.ciency. sough A ditch used to drain mine water. SOUR See “speci.c oxygen uptake rate (SOUR).” sour environment Environment containing signi.cant amounts of hydrogen sul.de. sour gas Natural gas containing impurities such as hydrogen sul.de which give
the gas an acrid odor. sour water Water containing hydrogen sul.de or other malodorous compounds. source The point of origin or part of a facility that generates or releases an excess
of a substance.
Southern Oscillation A circulation pattern in the atmosphere that brings low pressure to the eastern Paci.c and high pressure to the Indian Ocean. See also “El Ni.o/Southern Oscillation (ENSO).”
SOx See “sulfur oxides (SOX).”
Soxhlet Extraction Method An extraction process using trichloro.uoroethane to

determine the oil and grease content in a liquid. SoyGold® Biodegradable, nontoxic solvent by Ag Environmental Products LLC. sparingly soluble compounds Term used to describe compounds with solubility
ranges from near zero to a few thousand milligrams per liter. Sparjair Package wastewater treatment plant by Walker Process Equipment. Sparjer Aeration products by Walker Process Equipment. SparjLift One- or two-level air injection pump by Walker Process Equipment. sparkling water Carbonated water for which the carbon dioxide content comes
from the same source as the water. SPCC (1) Spill prevention control and countermeasures. (2) Spill prevention,
containment, and countermeasure. SPCCP See “Spill Prevention Control and Countermeasures Plan (SPCCP).” SPE Secondary particulate emissions. special waste Items such as household hazardous waste, bulky wastes including
refrigerators and pieces of furniture, and tires or used oil.

species A population of similar organisms that interbreed among themselves.
speci.c conductance The measure of electrical conductance of water or a water solution and the reciprocal of speci.c resistance. Usually stated in micromhos per cm.
speci.c gravity The ratio of the density of a substance to the density of water.
speci.c oxygen uptake rate (SOUR) An indicator of a sludge’s odor-causing potential by aerating a sludge sample and measuring the rate of oxygen depletion.
speci.c resistance A measure of total ionized solids concentration determined by the resistance of a 1 cm cube of water to the passage of electricity under standard conditions.
speci.c ultraviolet absorbance (SUVA) The amount of ultraviolet light that can be absorbed per unit of total organic carbon which may indicate DBP formation potential.
SpectraGuard™ Liquid antiscalant and stabilizer for reverse osmosis systems by Professional Water Technologies, Inc. spectrophotometer An instrument for measuring the amount of electromagnetic
radiation absorbed by a sample as a function of wavelength. Spectrum™ Aeration-mixing systems by Environmental Dynamics Inc. Speedi-Berm™ Secondary containment system by Aero Tec Laboratories, Inc. Spektrotherm® Low pressure, high intensity ultraviolet lamps by PCI-Wedeco
Environmental Technologies, Inc. spent caustic Waste product formed when petrochemicals and re.ned hydrocar
bons are treated with caustic soda solutions to remove impurities. spent regenerant Wastes from the regeneration of an ion exchange system. Sphaerotilus A .lamentous bacteria which commonly causes sludge bulking in
activated sludge wastewater treatment plants. Spher-Flo Single stage sewage pumps by Aurora Pump. sphericity A measure of roundness and wholeness of .lter media and ion exchange
resin beads. Spill Prevention Control and Countermeasures Plan (SPCCP) Plan covering
the release of hazardous substances as de.ned in the Clean Water Act. spill water Water released from an impoundment. spillway The channel designed to direct over.owing water at the top of a dam. Spira-Cel® Spiral wound, cross .ow .ltration membranes by Celgard LLC. Spiracone® Conical tank up.ow clari.er by USFilter/General Filter. Spiractor® Lime softener by USFilter/Warren. Spira.o Peripheral feed clari.er by Lakeside Equipment Corp. Spira.oc Peripheral feed clari.er with .occulation zone in outer raceway by
Lakeside Equipment Corp. Spiragester Combination digester and clari.er by Lakeside Equipment Corp. Spiragrit Grit removal system by Lakeside Equipment Corp. Spiral Flow® Water/solids separator by Alar Engineering Corp. spiral heat exchanger A type of heat exchanger used in heavy fouling applications. Spiral Scoop Dissolved air .otation skimming device by Krofta Engineering Corp. Spiral.ow Dewatering screen fabric by Geschmay GmbH.

Spiralift™ Screw pump by USFilter/Zimpro.
Spiralklean® Screenings washer by Parkson Corp.
Spiraltek™ Dry sump .lters by Osmonics, Inc.
Spira-Pac Package digester clari.er combination by Lakeside Equipment Corp.
Spiratex™ Point-of-use .ltration system by Osmonics, Inc.
Spirathickener Peripheral feed gravity thickener by Lakeside Equipment Corp.
Spiratrex Ultra.ltration membrane by Osmonics, Inc.
Spira-Twin Spiragester Clari.er/digester unit for primary and secondary sedimentation of trickling .lter ef.uents by Lakeside Equipment Corp.
Spiravac Peripheral feed clari.er with vacuum assisted sludge removal by Lake-side Equipment Corp.
Spirolift® Screw-type vertical conveyor by Spirac.
Spiropac® Screw-type compactor by Spirac.
Spiropress® Screw-type solids dewatering press by Spirac.
Spirosand® Shaftless grit classi.er by Andritz-Ruthner, Inc.
Spirovortex Activated sludge treatment system including tertiary .ltration by GL&V/Dorr-Oliver, Inc.
Split-ClarAtor™ Secondary clari.er by Waterlink/Aero-Mod Systems.
splitter box A chamber that equally divides incoming .ow into two or more streams.
spoil Dirt or rock removed from its original location by strip-mining, dredging, or construction.
sponge ball cleaning The use of .exible sponge balls added to a recirculating liquid to scour scale or other deposits that form on the inside of condenser or heat exchanger tubes.
spore A reproductive cell or seed of a microbe, often dormant or environmentally resistant.
sprawl Unplanned development of open land.
spray dryer Sludge-drying device utilizing centrifugal force to atomize sludge into .ne particles and spray them into the top of a drying chamber.
spray irrigation The spreading of treated wastewater on agricultural land by spraying.
spray tower scrubber A device that sprays alkaline water into a chamber where acid gases present to aid in the neutralizing of the gas.
Spray-Film® Vapor compression distillation unit by Aqua-Chem, Inc.
Spraymaster® Low-headroom packaged deaerator by Cleaver-Brooks.
spring A natural .ow of water from the ground.
spring turnover See “turnover.”
spring water Bottled water collected from an underground formation from which the water .ows naturally from the surface, or a bore hole that taps the spring and is located near where the spring emerges.
Sprint™ Submersible pump product line by Crane Pumps & Systems.
Sprout-Bauer Former name of Andritz-Ruthner, Inc. screening equipment product line.
Spyder™ Fixed-grid sludge withdrawal system by Roberts Filter Group.
SQBE Small quantity burner exemption.

SQG See “small quantity generator.”
SQHs See “small-quantity handlers.”
Squarex Circular sludge collector mechanism with pivoted corner extensions for square basins by GL&V/Dorr-Oliver, Inc.
squeegee See “small quantity generator (SQG).”
SR-7™ Ion exchange resins by Sybron Chemicals, Inc.
SRC Solvent-re.ned coal.
SRF See “State Revolving Fund (SRF).”
SRM Standard reference method.
SRT See “solids retention time (SRT).”
SS See “suspended solids (SS).”
SSA Sole source aquifer.
SSAC Soil site assimilated capacity.
SSI Screening Systems International.
SSMS Spark source mass spectrometry.
SSO See “sanitary sewer over.ow (SSO).”
SSPC Society for Protective Coatings. Formerly “Steel Structures Painting Council.”
SSPMA Sump and Sewage Pump Manufacturers Association.
SST See “stainless steel (SST).”
SSV See “settled sludge volume (SSV).”
Stabilaire Package contact stabilization treatment plant formerly offered by USFilter/Envirex.
stability index See “Langelier Saturation Index (LSI).”
stabilization pond A large shallow basin used for wastewater treatment by natural processes involving the use of algae and bacteria to accomplish biological oxidation of organic matter.
StablCal™ Formazin turbidity standards by Hach Co.
stable air A motionless mass of air that holds instead of dispersing pollutants.
stack (1) A vertical conveyance method for the elevated discharge and dispersion of pollutants. (2) Common term for the key element of an electrodialysis unit consisting of multiple membrane cells with electrodes on both ends.
stack effect Air, as in a chimney, that moves upward because it is warmer than the ambient atmosphere.
stack gas See “.ue gas.”
StackMasterIMS™ Continuous emissions monitor by Molecular Analytics LLC.
stage One of several units of a .ash evaporator, each of which operates at a successively lower pressure.
stagnant Motionless, not .owing in a current or stream.
Stahlermatic® Rotating biological contacter wastewater treatment system by Stahler GmbH.
stainless steel (SST) Corrosion resistant steel containing a minimum of 12% chromium as the principal alloying element.
stakeholder Any organization, governmental entity, or individual that has a stake in or may be impacted by a given approach to environmental regulation, pollution prevention, energy conservation, etc.
STAK.lter High volume vertical pressure screen .lter by Ever.lt Corp.

Stak-Tracker™ Continuous emissions monitoring system by GE Reuter-Stokes.
Standard Industrial Classi.cation (SIC) A U.S. government numbering system used to categorize industrial facilities.
Standard Methods Common abbreviation for the reference book Standard Methods for the Examination of Water and Wastewater, widely used in water and wastewater testing and analysis, and published jointly by APHA, AWWA, and WEF.
standard plate count See “heterotrophic plate count (HPC).”
standard seawater A widely accepted “standard” total dissolved solids concentration of approximately 36,000 mg/L, considered to be typical of most seawaters.
standard solution A solution whose strength or reacting value per unit volume is known.
standpipe A vertical, cylindrical water storage tank of uniform diameter with a height greater than its diameter.
Stanley Compo-Cast Former manufacturer of nonmetallic sludge collector wear shoes now made by Trusty Cook, Inc.
stapling The entanglement of stringy or .brous debris on a mesh or bar rack.
Star Filter® Filter press by Star Systems, Inc.
STAR® Anaerobic package plants by ADI Systems, Inc.
StarScreen In-channel .ne screen by Sernagiotto Technologies.
Sta-Sieve Static .ne screen by SWECO Engineering Corp.
Stata-Tube Mixer™ Motionless mixer by TAH Industries, Inc.
State Implementation Plan (SIP) Plans to implement air quality standards required of each state under the Clean Air Act.
State Revolving Fund (SRF) A U.S. EPA program awarding grants to states for use in community projects which comply with public health protection needs, with an emphasis on small drinking water systems.
static head The vertical distance between a .uid’s supply surface level and free discharge level.
Static Mixaerator™ Static mixing aerators by JDV Equipment Corp.
static mixer Motionless device consisting of .xed baf.es incorporated into channels or pipelines to create turbulence and mix additives added upstream.
static pile composting A composting method where piles of municipal wastewater solids are aerated to eliminate the need for remixing.
static screen Fine screen using a stationary, inclined screen deck that acts as a sieve to remove solids from liquids. Also known as a “rundown screen” or “sidehill screen” or “static screen.”
static tube diffuser A coarse bubble diffuser consisting of a vertically oriented cylinder with internal baf.es to promote air/water mixing.
stationary source A .xed-site producer of pollution, mainly power plants and other facilities using industrial combustion processes.
stator The stationary member of an electric motor or generator.
Stato-Screen Static screen by Vulcan Industries, Inc.
Stauffer Chemical Former name of Rhone-Poulenc Basic Chemical Co.
steady state An equilibrium condition that exists in a system.
Steady Stream Turbidimeter by GLI International.

steam chest The steam chamber adjacent to a heat exchanger tubesheet.
steam stripper The process of removing volatile and semi-volatile contaminants from liquid where steam and liquid are passed countercurrently through a packed tower.
STEL See “short term exposure limit (STEL).”
STEM Scanning transmission-electron microscope.
Stengel Baf.e Inlet baf.e for rectangular sludge collector by USFilter/Zimpro.
stenothermophiles Bacteria that grow best at temperatures above 60°C.
step aeration Variation of the activated sludge process where settled wastewater is introduced at several points in the aeration tank to equalize the F/M ratio.
Step Screen® In-channel .ne screen by Hans Huber GmbH.
Stepaire Circular package step aeration wastewater treatment plant formerly offered by USFilter/Envirex.
sterile Free from bacteria or other microorganisms.
sterilization The destruction or removal of all living organisms within a system.
Ster-L-Ray™ Germicidal ultraviolet lamps by Atlantic Ultraviolet Corp.
SternPAC™ Polyaluminum coagulant by Sternson Ltd.
Stiff & Davis Index Index used to determine the saturation point of calcium carbonate in seawater or other highly saline water.
STIG Steam injected gas turbine.
still Apparatus used in distillation.
stilling well A tube or chamber used to dampen waves or surges in a large body of water usually used for purposes of water level measurement.
Sti-P3® Steel tank standard for double wall underground tank with cathodic protection by Steel Tank Institute.
stock solution A concentrated chemical solution, often used as a reagent.
stoichiometric The ratio of chemical substances reacting in water that corresponds to their combining weights in the theoretical chemical reaction.
stoker A mechanical device that feeds solid fuel to a furnace.
Stokes’ Law Law that de.nes the settling velocity of a particle based on its density and size.
stop log A removable wooden, steel, or concrete bulkhead which .ts into vertical grooves in a channel to stop water .ow.
storage lagoon A lagoon constructed with a sealed bottom used to store and collect solids.
Stord Former name of Atlas-Stord, Inc.
Storm King™ Vortex-type separation system by H.I.L. Technology, Inc.
storm sewer Collection system of underground piping used to remove water resulting from precipitation runoff.
Stormceptor® Stormwater treatment device by Stormceptor Corp.
StormFilter™ Stormwater .ltration and management system by Stormwater Management.
StormGate™ High .ow bypass by Stormwater Management.
StormTreat™ Stormwater collection and treatment system by StormTreat Systems, Inc.
stormwater Water resulting from precipitation runoff.

STP (1) Sewage treatment plant. Equivalent to “WWTP.” (2) Standard temperature
and pressure. Straightline® Group of wastewater treatment products by USFilter/Envirex. strainer A device that retains solids but allows liquids to .ow through. Strain-O-Matic Self-cleaning strainer by Hayward Industrial Products, Inc. StrainPress® Screenings and trash removal compactor by Parkson Corp. Stranco Former name of USFilter/Stranco. Strantrol Chemical controller for disinfection systems by USFilter/Stranco. Strata Clear Water .otation separator by Smith & Loveless, Inc. StrataMix Fine bubble diffuser by Wil.ey Weber, Inc. Strata-Sand™ Continuously backwashed gravity sand .lter by F.B. Leopold Com
pany, Inc. (U.S.) and Simon-Hartley, Ltd. (U.K.). Stratavap Evaporator system by Licon, Inc. stratosphere The level of the atmosphere containing most of the earth’s ozone
that lies between the troposphere and the mesosphere. stray current corrosion Electrochemical corrosion caused by stray currents leak
ing from an electrical installation. Stream Saver™ Automated spill control system by ILC Dover, Inc. streaming current The net ionic and colloidal surface charges of suspended solid
particles in solution. streaming current detector (SCD) Measuring device used to detect and monitor
the net electrical charge of particles in solution after coagulants have been added. Streamline Flow proportional sampler by American Sigma, Inc. Streamline Rectangular chain and .ight collector by Purestream, Inc. streptococcus A genus of bacteria that includes some of the most common human
pathogens. stress corrosion cracking Formation of cracks caused by the action of a corrosive
medium in combination with tensile stress. stress relieving Heat treatment carried out to reduce internal stresses in steel. Stress-Key Pre-cast concrete packaged sewage treatment plants by Marolf, Inc. strip cropping Growing crops in a systematic arrangement of strips or bands that
serve as barriers to wind and water erosion. strip mining A method of mining where surface soil and strata are removed to
gain access to the mineral deposits. stripper Device used to remove volatile and semi-volatile contaminants from water. Stripper® Multistaged diffused-bubble aeration system by Lowry Aeration Sys
tems, Inc. Stripperator Treatment unit for hydrocarbon-contaminated water by Ejector Sys
tems, Inc. strong acid An acid that approaches 100% ionization in dilute solutions. strong acid cation exchanger A cation exchange resin with an exchange site
capable of splitting neutral salts to form their corresponding free acids. strong acid ion exchanger Ion exchange using a cationic resin that contains exchangeable functional groups derived from a strong acid. strong base anion exchanger An anion exchange resin with an exchange site capable of splitting neutral salts to form their corresponding free bases.

strong base ion exchange Ion exchange using an anionic resin that contains exchangeable functional groups.
strong base load factor z The sum of alkalinity, sulfate, chloride, silica, and carbon dioxide expressed as calcium carbonate equivalents.
Stuart-Carter Walking beam .occulator by JDV Equipment Corp.
SU Standard unit.
subchronic Of intermediate duration, usually used to describe studies or levels of exposure between 5 and 90 days.
subdrainage The control and removal of excess groundwater, usually by means of pipe drains that intercept seepage and/or lower the water table.
subituminous coal A grade of coal with a heat content higher than that of lignite but lower than bituminous.
sublimation The process of changing a gas to a solid, or a solid to a gas, without going through the liquid phase.
submerged aquatic vegetation Vegetation such as sea grasses that cannot withstand excessive drying and therefore live with their leaves at or below the water surface.
submerged MBR An MBR con.guration in which the membranes are immersed directly within the activated sludge reactor.
submerged tube evaporator An evaporator where steam enters a tube bundle submerged in the .uid to be boiled.
submerged weir A weir which when in use has a water level on the downstream side at an elevation equal to, or higher than, the weir crest. Also called a “drowned weir.”
subnatant Liquid remaining beneath the surface of .oating solids.
Suboscreen® In-channel rotary .ne screen by Andritz-Ruthner, Inc. (Western Hemisphere) and USFilter/Contra-Shear.
Subrotor Progressing cavity pump by Mono.o.
subsidence The lowering of the natural land surface due to a reduction of the .uid pressure, removal of underlying supporting material, compaction due to wetting, or added loads on the land surface.
subsonic .ow Liquid .ow at a speed that is less than the speed of sound in the .uid.
substrate The organic matter or nutrients used as food substances during biological wastewater treatment.
subtropics The regions bordering the tropical zone.
Suco.ow® Aeration diffuser by Huber+Suhner AG.
suction head The head between the centerline of a pump and the water level on the pump’s suction side.
Sulf Control® Sul.de inhibitor for prevention of hydrogen sul.de formation by NuTech Environmental Corp.
sulfamic acid Acid often used as a cleaning agent. Chemical formula is HSO3NH2.
sulfate The divalent, negative SO4 anion or an ester containing the anion.
sulfate-reducing bacteria Bacteria capable of reducing sulfate or other forms of oxidized sulfur to hydrogen sul.de gas.
SulfaTreat®-OC Hydrogen sul.de removal process by SulfaTreat Co.

Sulfaver Reagent chemical used to determine phosphates concentration in water by Hach Co.
Sulfex® Sul.de precipitation process for heavy metal removal by USFilter/Industrial Wastewater Systems.
sul.de The divalent, negative S anion or a salt containing the anion.
sulfonator Device used to inject and meter sulfur dioxide to dechlorinate water.
sulfonic acid An organic acid used to provide some cation exchange resin with its ion exchange capability. Chemical formula is SO3H.
SulfOx™ Biological oxidant for elimination of odors and toxicity from wastewater and sludges by Sybron Chemicals, Inc.
Sulftech® Reducing agent by General Chemical Corp.
sulfur A .ammable, nonmetallic element with many commercial uses. Chemical symbol is S.
sulfur oxides (SOX) Air contaminants resulting from the combustion of fuels containing sulfur in the presence of oxygen.
sulfuric acid A toxic corrosive acid capable of dissolving most metals. Chemical formula is H2SO4.
Sulfur-Rite™ A hydrogen sul.de and light mercapton scavenger system by USFil-ter/Gas Technologies.
sullage Wastewater that drains from a home, farmyard, refuse heap, or street.
Sulzer Screenings grinder by GL&V/Dorr-Oliver, Inc.
Sumigate® Rubber dam for combined sewer over.ow applications by Rodney Hunt Co.
sump A pit or reservoir that serves to collect water or wastewater for subsequent removal from the system.
sump pump A pump used to remove water or wastewater from a sump or wet well.
Sumpaire™ Self-aspirating jet aerator by ABS Pumps, Inc.
Sump-Gard® Vertical centrifugal pump by Vanton Pump & Equipment Corp.
Suparator® Oil/water separator by Lemacon Techniek B.V.
super austenitic stainless steel Stainless steel alloyed with more than 4% molybdenum.
Super Blend™ Cellulose acetate reverse osmosis membranes by TriSep Corp.
Super Detox™ Encapsulation process to chemically stabilize furnace dust and other heavy metal residues by Conversion Systems, Inc.
Super Dome™ Ceramic dome diffuser by Ferro Corp.
Super Shredder® In-line macerator by Franklin Miller, Inc.
Super Sieve Screen Sieve screen by Sizetec, Inc.
Superblock II® Filter underdrain with water and air/water backwash capabilities by F.B. Leopold Co., Inc.
Super-Cel® Diatomaceous earth .lter media by Celite Corp.
Supercell Dissolved air .otation unit by Krofta Engineering Corp.
Superceptor® Pump station for oily and greasy wastewater by Thermaco, Inc.
superchlorination Chlorination with excess dosages which insures disinfection with short contact times and which produces free or combined residuals so large as to require dechlorination.

supercool To cool a substance in its liquid state at a temperature below its freezing point.
supercritical water oxidation (SCWO) High temperature/pressure wastewater treatment process where organic material is oxidized at temperatures above a .uid’s critical point.
Super-D-Canter® Solid bowl decanter centrifuge by Alfa Laval Separation, Inc.
Superdraw Supernatant withdrawal unit by Walker Process Equipment.
Super.oc® High charge cationic .occulant by Cytec Industries, Inc.
Superfund A U.S. federal law authorizing identi.cation and remediation of unsu
pervised hazardous waste sites. See “CERCLA.”
Superfund Amendments and Reauthorization Act A 1986 U.S. law passed to reauthorize and expand CERCLA and require public disclosure of chemical release information and development of an emergency response plan.
Superfund Innovative Technology Evaluation (SITE) EPA-supported research, development, and demonstration projects designed to develop new remediation technologies.
Superfuser Fine bubble diffuser by USF/Envirex. superheat The sensible heat in a gas above the amount needed to maintain the gas phase. superheated steam Steam with additional heat added after vaporization, increas
ing its temperature and energy. Supermal Pearlitic malleable iron chain material by Jeffrey Chain Corp. supernatant Liquid above the settled sludge layer in a sedimentation basin. Superpulsator® Solids contact clari.er utilizing inclined plates and intermittent
pulsing to expand the sludge blanket by In.lco Degremont, Inc. SuperSand™ Continuous sand .lter by Waterlink Separations, Inc. supersaturation A solution containing more of a dissolved substance than is
usually possible at equilibrium. SuperScraper™ Bottom sludge scraper by Waterlink Separations, Inc. SuperSettler™ Inclined plate clari.er by Waterlink Separations, Inc. SuperSkimmer™ Surface scum skimmer by Waterlink Separations, Inc. Superslant™ Inclined plates for clari.cation by Filtronics, Inc. Supersorbon Solvent recovery plant by Dedert Corp. Superstill Former name of VaPure vapor compression still by Paul Mueller Co. Superthickener Large diameter center pier gravity thickener by GL&V/Dorr-
Oliver, Inc. Super-Trasher Vertical sludge pump by Vanton Pump & Equipment Corp. supplied air respirator (SAR) Respirator using an airline or tank to provide air
to the facepiece. support gravel Layers of graded gravel between underdrain openings and .lter
media to prevent media from leaking into the underdrain. Supracell Dissolved air .otation unit by Krofta Engineering Corp. Suprex™ Mixed bed-type condensate polisher by Graver Co. surcharge (1) The height of wastewater in a sewer manhole above the crown of
the sewer when the sewer is .owing completely full. (2) Loads on a system beyond those normally anticipated. (3) An extra monetary charge imposed — especially on .ows into a wastewater collection system — when set quantity or quality limits are exceeded.

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