Glossary: Wastewater

List of terms commonly used in the industrial & municipal wastewater treatment industry.

Acid

A substance that forms hydrogen ions upon dissolving in water and neutralizes bases to form a salt plus water. Acids are characterized by their tendency to lose a proton (or to gain an electron pair) in reactions. Acids turn litmus paper red and can be

Acid Deposition

Precipitation, in either wet or dry form, or acids and acid-forming compounds. Often referred to as "acid rain". Key sources of acids are emissions of sulfur and nitrogen oxides.

Acid Mine Drainage

Acidic runoff from active and abandoned mines, especially coal mines (sulfuric acid). Enters both surface and groundwater.

Acid Neutralizing Capacity (ANC)

Ability of waters and soils to absorb additional inputs of acidity.

Activated Sludge

A microbial enrichment culture consisting of a mixed and largely uncontrolled consortium of micro and macro organisms that remove (metabolize) waste water inorganics and organics or transform them into environmentally acceptable forms.

Active Ingredient

Chemical ingredient that is biolgically active. May affect humans, fish, wildlife, and vegetation.

Advanced Wastewater Treatment

Any treatment of sewage that goes beyond the secondary or biological water treatment stage and includes the removal of nutrients such as phosphorus and nitrogen and a high percentage of suspended solids. (See primary, secondary treatment.)

Aeration

A process which promotes biological degradation of organic matter in water. The process may be passive (as when waste is exposed to air), or active (as when a mixing or bubbling device introduces the air).

Aerobic

Oxygen-consuming organism.

Aerobic Treatment

Process by which microbes decompose complex organic compounds in the presence of oxygen and use the liberated energy for reproduction and growth. (Such processes include extended aeration, trickling filtration, and rotating biological contactors.)

Algae

A general category of photosynthesizing unicellular and multicellular organisms primarily aquatic. Some are prokaryotes (cyanobacteria, formerly known as blue-green algae) but most belong to the kingdom of Protista, eukaryotes that are neither plants, an

Algal Bloom

Explosion of algae populations in surface waters usually caused by an increase in nutrients such as nitrates and phosphates. Such high population denisities may not last long and may occur periodically throughout the year. Some algal blooms produce toxi

Algicide

A substance that is toxic to algae, such as chlorine bleach.

Alkali

Various soluble salts, principally of sodium, potassium, magnesium, and calcium, that have the property of combining with acids to form neutral salts and may be used in chemical water treatment processes.

Alkaline

1) The opposite of acid, also called basic; having a high pH value and thus a low concentration of hydrogen ions and a high concentration of hydroxide ions. 2) Containing alkalies, as in alkaline soil or an alkaline chemical reaction.

Amino Acids

Amino Acids are the chemical units that make up proteins.

Anaerobic

A biological process which occurs in the absence of oxygen.

Aqueous Solubility

The extent to which a compound will dissolve in water. The log of solubility is generally inversely related to molecular weight.

Aquifer

An underground geological formation, or group of formations, containing usable amounts of groundwater that can supply wells and springs.

Aromatic

A type of hydrocarbon, such as benzene or toluene, added to gasoline in order to increase octane. Some aromatics are toxic.

Bacteria

(Singular 'bacterium') A large group of prokaryotic microorganismd characterized by multiplying via fission or forming spores, and generally lacking clorophyll or a distinct nucleus surrounded by a membrane. Bacteria are unicellular and often classified

Baffle

A flat board or plate, deflector, guide or similar device constructed or placed in flowing water or slurry systems to cause more uniform flow velocities, to absorb energy, and to divert, guide, or agitate liquids (water, chemical solutions, slurry).

Bioaccumulants

Substances that increase in concentration in living organisms as they take in contaminated air, water, or food because the substances are very slowly metabolized or excreted.

Bioassay

A method used to determine the toxicity of specific chemical contaminants. A number of individuals of a sensitive species are placed in water containing specific concentrations of the contaminant for a specified period of time.

Bioaugmentation

The introduction of cultured microorganisms into the subsurface environment for the purpose of enhancing bioremediation of organic contaminants. Generally the microorganisms are selected for their ability to degrade the organic compounds present at the re

Biodegradable

Capable of being decomposed into natural substances, such as carbon dioxide & water, by biological processes, especially bacterial action.

Biologicals

Vaccines, cultures and other preparations made from living organisms and their products, intended for use in diagnosing, immunizing, or treating humans or animals, or in related research.

Biomass

All of the living material in a given area; often refers to vegetation.

Bioremediation

The use of living organisms (e.g., bacteria) to clean up oil spills or remove other pollutants from soil, water, and wastewater, use of organisms such as non-harmful insects to remove agricultural pests or counteract diseases of trees, plants, and garden

Biotechnology

Techniques that use living organisms or parts of organisms to produce a variety of products (from medicines to industrial enzymes) to improve plants or animals or to develop microorganisms to remove toxics from bodies of water, or act as pesticides.

BOD

(Biological Oxygen Demand) An indication of the extent to which water is polluted by sewage or other organic waste. It is a measure of the dissolved oxygen consumed by microorganisms as they break down the organic matter in a sample of water; the greater

BOD5

The biochemical oxygen demand over a 5-day period at a standard temperature of 20°C (68° F) and a standard atmospheric pressure.

Buffering Capacity

Ability of waters or soils to absorb acids into solution without drastically affecting acidity. Determined by amount of buffering agent, such as limestone, that is present.

Catalyst

A substance that changes the speed or yield of a chemical reaction without being consumed or chemically changed by the chemical reaction.

Chlorination

Adding chlorine to water or wastewater, generally for the purpose of disinfection, but frequently for accomplishing other biological or chemical results. Chlorine also is used almost universally in manufacturing processes, particularly for the plastics in

Clarifer

A large circular or rectangular tank or basin in which water is held for a period of time, during which the heavier suspended solids settle to the bottom. Clarifiers are also called settling basins and sedimentation basins.

Closed-loop recycling

Reclaiming or reusing wastewater for non-potable purposes in an enclosed process.

Coagulants

Chemicals that cause very fine particles to clump together into larger particles. This makes it easier to separate the solids from the water by settling, skimming, draining or filtering.

COD

(Chemical Oxygen Demand) The amount of mg/L or ppm of oxygen required to completely oxidize all compounds in a sample of water. Chromium dioxide, an aggressive oxidant, and heat is used to drive to completion the chemical oxidation of the compounds prese

Cohesion

Molecular attraction which holds two particles together.

Coliform organism

Microorganisms found in the intestinal tract of humans and animals. Their presence in water indicates fecal pollution and potentially dangerous bacterial contamination by disease-causing microorganisms.

Combined Sewer Overflow

Combined storm and sanitary drainage that exceeds capacity of a waste water treatment plant. Overflow is discharged directly to surface water. Occurs during periods of heavy rain and runoff.

Conductance

A rapid method of estimating the dissolvedsolids content of a water supply. The measurement indicates the capacity of a sample of water to carry an electrical current, which is related to the concentration of ionized substances in the water.

Cultural Eutrophication

Overenrichment of an aquatic ecosystem with plant nutrients - mainly nitrates and phosphates - from such human activities as agriculture and municipal sewage treatment.

Decant

To draw off the upper layer of liquid (water) after the heavier material (a solid or another liquid) has settled.

Decomposition

The conversion of chemically unstable materials to more stable forms by chemical or biological action. If organic matter decays when there is no oxygen present (anaerobic conditions or putrefaction), undesirable tastes and odors are produced. Decay of org

Decontamination

Removal of harmful substances such as noxious chemicals, harmful bacteria or other organisms, or radioactive material from exposed individuals, rooms and furnishings in buildings, or the exterior environment.

Degradation

Chemical or biological breakdown of a complex compound into simpler compounds.

Denitrification

Bacterial reduction of nitrite to gaseous nitrogen under anaerobic conditions.

Diatomaceous earth (diatomite)

Chalk-like material (fossilized diatoms) used to filter out solid waste in wastewater treatment plants.

Digestion

The biochemical decomposition of organic matter, resulting in partial gasification, liquefaction, and mineralization of pollutants.

Dioxins

Family of over 100 synthetic chlorinated hydrocarbons that are highly toxic at low doses. May cause cancer and birth defects in humans.

Principal current use is in herbicides.

Dissolved Oxygen

The oxygen freely available in water, vital to fish and other aquatic life and for the prevention of odors. DO levels are considered a most important indicator of a water body's ability to support desirable aquatic life. Secondary and advanced waste treat

Dissolved Solids

Disintegrated organic and inorganic material in water. Excessive amounts make water unfit to drink or use in industrial processes.

Effluent

Water or some other liquid-raw, partially or completely treated-flowing from a reservoir, basin, treatment process or treatment plant.

Emulsify

To cause one liquid substance to form colloidal suspension in another (an emulsion). Detergents cause grease to emulsify in water so that it can be removed from dishes, clothing, etc.

Emulsion

A colloid mixture of two or more immersible (not readily mixed) liquids; a mixture in which one or more liquids is suspended in another liquid without dissolving. An emulsion such as oil and water usuaully separates into its separate components unless an

Enrichment

The addition of nutrients (e.g., nitrogen, phosphorus, carbon compounds) from sewage effluent or agricultural runoff to surface water, greatly increases the growth potential for algae and other aquatic plants.

Enteric

Of intestinal origin, especially applied to wastes or bacteria.

Enzyme

Biological catalysts; complex proteins produced by plant and animal tissues to initiate or speed up specific reactions between other chemicals without undergoing permanent structural change. For example, the enzyme pepsin helps digest proteins. Most enz

Facultative

Used to describe organisms that are able to grow in either the presence or absence of a specific environmental factor (e.g., oxygen). See also facultative anaerobe.

Fat

Any class of organic chemical compounds, usually mixtures of triglycerides or other lipids, that are solid at room temperature. Fats are common in plants and animals, used to store highly concentrated energy. Fats are usually compound esters of several

Fatty Acid

Any of large group of organic acids; many are essential for metabolism. Long-chain fatty acids are components of lipids and waxes. Acetic acid and oleic acid are both fatty acids.

Flocculation

The gathering together of fine particles in water by gentle mixing after the addition of coagulant chemicals to form larger particles.

Flow Rate

The rate, expressed in gallons-or liters-per-hour, at which a fluid escapes from a hole or fissure in a tank. Such measurements are also made of liquid waste, effluent, and surface water movement.

FOG

(Fat, Oils, Grease) Most wastewater collection system blockages can be traced to FOG. Blockages in the wastewater collection system are serious, causing sewage spills, manhole overflows, or sewage backups in homes and businesses. Enzymes are extremely ef

GRAS

An acronym for the phrase "Generally Recognized As Safe" under sections 201(s) and 409 of the Federal Food, Drug, and Cosmetic Act.

Hydrocarbon

Chemicals that consist entirely of hydrogen and carbon. Hydrocarbons contribute to air pollution problems like smog.

Hydrochlorination

The application of hypochlorite compounds to water for the purpose of disinfection.

Hydrogen Peroxide

Hydrogen peroxide is used to increase the dissolved oxygen content of groundwater to stimulate aerobic biodegradation of organic contaminants. Hydrogen peroxide is infinitely soluble in water, but rapidly dissociates to form a molecule of water [H(2)O] an

Hydrogen Sulfide

Gas emitted during organic decomposition. Also a byproduct of oil refining and burning. Smells like rotten eggs and, in heavy concentration, can kill or cause illness.

Hypoxic

A condition of low oxygen concentration, below that considered aerobic. in situ: in its original place; unmoved; unexcavated; remaining in the subsurface.

In Situ

In place, the original location, in the natural environment.

Indirect Discharge

Introduction of pollutants from a non-domestic source into a publicly owned waste-treatment system. Indirect dischargers can be commercial or industrial facilities whose wastes enter local sewers.

Industrial Waste

Unwanted materials produced in or eliminated from an industrial operation and categorized under a variety of headings, such as liquid wastes, sludge, solid wastes, and hazardous wastes.

Inflow

Entry of extraneous rain water into a sewer system from sources other than infiltration, such as basement drains, manholes, storm drains, and street washing.

Influent

Water or other liquid-raw or partially flowing INTO a reservoir, basin, treatment process or treatment plant.

Inorganic

Material such as sand, salt, iron, calcium salts and other mineral materials. Inorganic substances are of mineral origin, whereas organic substances are usually of animal or plant origin.

Interceptor Sewers

Large sewer lines that, in a combined system, control the flow of sewage to the treatment plant. In a storm, they allow some of the sewage to flow directly into a receiving stream, thus keeping it from overflowing onto the streets. Also used in separate s

Lagoon

A shallow, artificial treatment pond where sunlight, bacterial action, and oxygen work to purify wastewater; a stabilization pond. An aerated lagoon is a treatment pond that uses oxygen to speed up the natural process of biological decomposition of organi

Leachate

A liquid that results from water collecting contaminants as it trickles through wastes, agricultural pesticides or fertilizers. Leaching may occur in farming areas, feedlots, and landfills, and may result in hazardous substances entering surface water, gr

Metabolism

The sum of the chemical reactions occurring within a cell or a whole organism; includes the energy-releasing breakdown of molecules (catabolism) and the synthesis of new molecules (anabolism).

Microbial Growth

The activity and growth of microorganisms such as bacteria, algae, diatoms, plankton and fungi.

Microcosm

A diminutive, representative system analogous to a larger system in composition, development, or configuration. As used in biodegradation treatability studies, microcosms are typically constructed in glass bottles or jars.

Microorganisms

Bacteria, yeasts, simple fungi, algae, protozoans, and a number of other organisms that are microscopic in size. Most are beneficial but some produce disease. Others are involved in composting and sewage treatment. Milligrams/liter (mg/l): A measure of co

Mineralization

The release of inorganic chemicals from organic matter in the process of aerobic or anaerobic decay.

Municipal Discharge

Discharge of effluent from waste water treatment plants which receive waste water from households, commercial establishments, and industries in the coastal drainage basin. Combined sewer/separate storm overflows are included in this category.

Municipal Sewage

Wastes (mostly liquid) originating from a community; may be composed of domestic wastewaters and/or industrial wastewaters.

Neutralization

Decreasing the acidity or alkalinity of a substance by adding alkaline or acidic materials, respectively.

Nitrate

Plant nutrient and inorganic fertilizer that enters water supply sources from septic systems, animal feed lots, agricultural fertilizers, manure, industrial waste waters, sanitary landfills and garbage dumps.

Nitrification

The process whereby ammonia in wastewater is oxidized to nitrite and then to nitrate by bacterial or chemical reactions.

Nitrogen Fixation

The biological or chemical process by which elemental nitrogen, from the air, is converted to organic or available nitrogen.

Nutrient

Any substance assimilated by living things that promotes growth. The term is generally applied to nitrogen and phosphorus in wastewater, but is also applied to other essential and trace elements.

Obligate Aerobes

Organisms that require the presence of molecular oxygen ([O(2)] for their metabolism.

Obligate Anaerobes

Organisms for which the presence of molecular oxygen is toxic. These organisms derive the oxygen needed for cell synthesis from chemical compounds.

Organic Chemicals/Compounds

Animal or plant-produced substances containing mainly carbon, hydrogen, nitrogen, and oxygen.

Organic Matter

Carbonaceous waste contained in plant or animal matter and originating from domestic or industrial sources.

Oxidation Pond

A structure for purifying sewage, consisting of a pond in which bacterial action is allowed to slowly oxidize (break down) the effluent.

Oxidizing Agent

Any substance that is capable of removing electrons from another substance. An oxidizing agent carries out the process of oxidization and is itself reduced.

Oxygen-Depleting Waste

Organic material whose decomsition is accomplished by aerobic bacteria

Packed Tower Aeration

A method of treating water to remove volatile organic chemical (VOCs) contaminants. As water is mixed with air, VOCs move from water to air which then passes through carbon filters to trap the contaminants.

Particulate

Very small solid suspended in water. They vary in size, shape, density, and electrical charge, can be gathered together by coagulation and flocculation.

pH

A measure of the acidity of a solution. pH is equal to the negative logarithm of the concentration of hydrogen ions in a solution. A pH of 7 is neutral. Values less than 7 are acidic, and values greater than 7 are basic.

Pharmacokinetics

The dynamic behavior of chemicals inside biological systems; it includes the processes of uptake, distribution, metabolism, and excretion.

Phenols

Organic compounds that are byproducts of petroleum refining, tanning, and textile, dye, and resin manufacturing. Low concentrations cause taste and odor problems in water; higher concentrations can kill aquatic life and humans.

Phosphates

Certain chemical compounds containing phosphorus.

Phosphorus

An essential chemical food element that can contribute to the eutrophication of lakes and otherwater bodies. Increased phosphorus levels result from discharge of phosphorus-containing materials into surface waters.

Plate Count

A count of the number of colonies gives the number of bacteria in the portion of the sample that was taken.

Point Source

A stationary location or fixed facility such as an industry or municipality that discharges pollutants into air or surface water through pipes, ditches, lagoons, wells, or stacks; a single identifiable source such as a ship or a mine.

Polymer

A chemical formed by the union of many monomers (a molecule of low molecular weight). Polymers are used with other chemical coagulants to aid in binding small suspended particles to larger chemical flocs for their removal from water. All polyelectrolytes

Primary Waste Treatment

First steps in wastewater treatment; screens and sedimentation tanks are used to remove most materials that float or will settle. Primary treatment removes about 30 percent of carbonaceous biochemical oxygen demand from domestic sewage.

Procaryotes

A cellular organism in which the nucleus has no limiting membrane.

Proteins

Complex nitrogenous organic compounds of high molecular weight made of amino acids; essential for growth and repair of animal tissue. Many, but not all, proteins are enzymes.

Radical

A group of atoms that is capable of remaining unchanged during a series of chemical reactions. Such combinations (radicals) exist in the molecules of many organic compounds; sulfate (SO42-) is an inorganic radical.

Recombinant Bacteria

A microorganism whose genetic makeup has been altered by deliberate introduction of new genetic elements. The offspring of these altered bacteria also contain these new genetic elements, i.e. they "breed true."

Reduction

Reduction is the addition of hydrogen, removal of oxygen, or the addition of electrons to an element or compound. Under anaerobic conditions (no dissolved oxygen present), sulfur compounds are reduced to odor-producing hydrogen sulfide (H2S and other comp

Residual

Amount of a pollutant remaining in the environment after a natural or technological process has taken place, e.g., the sludge remaining after initial wastewater treatment, or particulates remaining in air after it passes through a scrubbing or other proce

Respiration

The process in which an organism uses oxygen for its life processes and gives off carbon dioxide.

Sanitary Sewer

A sewer that transports only wastewaters (from domestic residences and/or industries) to a wastewater treatment plant.

Saprophytes

Organisms living on dead or decaying organic matter that help natural decomposition of organic matter in water.

Secondary Treatment

The second step in most publicly owned waste treatment systems in which bacteria consume the organic parts of the waste. It is accomplished by bringing together waste, bacteria, and oxygen in trickling filters or in the activated sludge process. This trea

Septic System

An onsite system designed to treat and dispose of domestic sewage. A typical septic system consists of a tank that receives waste from a residence or business and a system of tile lines or a pit for disposal of the liquid effluent (sludge) that remains af

Settling Tank

A holding area for wastewater, where heavier particles sink to the bottom for removal and disposal.

Skimming

Using a machine to remove oil or scum from the surface of the water.

Sludge

A semi-solid residue from any of a number of air or water treatment processes; can be a hazardous waste.

Slurry

A watery mixture or suspension of insoluble (not dissolved) matter; a thin watery mud or any substance resembling it (such as a grit slurry or a lime slurry).

Supernatant

Liquid removed from settled sludge. Supernatant commonly refers to the liquid between the sludge on the bottom and the water surface of a basin or container.

Supersaturated

An unstable condition of a solution (water) in which the solution contains a substance at a concentration greater than the saturation concentration for the substance.

Suspended Solids

Fine materials carried by water. Contribute to water's cloudiness or turbidity.

Synergism

The cooperative action of two or more organisms producing a greater total result than the sum of their independent effects; chemicals or muscles in synergy enhance the effectiveness of one another beyond what an individual could have produced.

Tertiary Treatment

An enhancement of normal sewage treatment operations to provide water of potable quality using further chemical and physical treatment; the highest drinking water standard achieved in the U.S.

Treated Wastewater

Wastewater that has been subjected to one or more physical, chemical, and biological processes to reduce its pollution of health hazard.

Treatment Plant

A structure built to treat wastewater before discharging it into the environment.

TSS

(Total Suspended Solids) The amount of solid material in water that can be captured on a filter with a pore size of one micrometer. Total Suspended Solids is determined by passing a known volume of sample water through a pre-weighted filter, drying, then

Turbidity

The cloudy appearance of water caused by the presence of suspended and colloidal matter. In the waterworks field, a turbidity measurement is used to indicate the clarity of water. Technically, turbidity is an optical property of the water based on the amo

VFA

Volatile Fatty Acids - Volatile fatty acids are fatty acids with a carbon chain of six carbons or fewer. They can be created through fermentation in the intestine. Examples include: acetate, propionate, butyrate

Volatile Acids

Acids produced during digestion. Fatty acids which are soluble in water and can be steam-distilled at atmospheric pressure. Also called "organic acids." Volatile acids are commonly reported as equivalent to acetic acid.

Volatile Liquids

Liquids which easily vaporize or evaporate at room temperature.

Volatile Organic Compound (VOC)

Any organic compound which evaporates readily to the atmosphere. VOCs contribute significantly to photochemical smog production and certain health problems.

Volatile Solids

Those solids in water or other liquids that are lost on ignition of the dry solids at 550 degrees C.

Xenobiote

Any biotum displaced from its normal habitat; a chemical foreign to a biological system.