Terminology

Question 1

The removal of metal, rocks, rags, sand, eggshells, and similar materials which may hinder the operation of a wastewater treatment plant.

Answer 1

Preliminary treatment

Question 2

it is water purification based on the difference in density of the polluting substance and the medium, the former being removed either by rising or settling. This process can include screening, grit removal, sedimentation, sludge dig. A wastewater treatment process that takes place in a rectangular or circular tank and allows those substances in wastewater that readily settle or float to be separated from the water being treated.
It is:
(1) The first major treatment in a wastewater treatment facility, used for the purpose of sedimentation. (2) The removal of a substantial amount of suspended matter, but little or no colloidal and dissolved matter. (3) Wastewater treatment processes usually consisting of clarification with or without chemical treatment to accomplish solid-liquid separation.

Answer 2

Primary Treatment

Question 3

Biological sewage treatment process that occurs in two steps. First, micro-organisms are used to break down contaminants dissolved in sewage that are organic in origin. This occurs in a series of aerated tanks. Second, micro-organisms and other solid materials are then settled out of the sewage in secondary clarifiers.

Answer 3

Secondary Treatment

Question 4

Any process of water renovation that upgrades treated wastewater to meet specific reuse requirements. May include general clean-up of water or removal of specific parts of wastes insufficiently removed by conventional treatment processes.
Typical processes include chemical treatment and pressure filtration. Also called “advanced waste treatment.” It is the treatment of wastewater beyond the secondary or biological stage; term normally implies the removal of nutrients, such as phosphorus and nitrogen, and a high percentage of suspended solids; term now being replaced by advanced waste treatment.

Answer 4

Tertiary Treatment

Question 5

A furtherer stayed of treating sewage by removing suspended solids. Consequential removal of residual BOD may occur. The use of filtration to remove microscopic particles from wastewater that has already been treated to a Secondary Level.

Answer 5

Effluent Polishing

Question 6

Treatment methods in which the application of physical forces predominates as a means for removal of wastewater constituents; includes flocculation, sedimentation, flotation, filtration, screening, mixing and gas transfer.

Answer 6

Unit Operations, Physical

Question 7

Treatment methods in which the removal or conversion of constituents is brought about through the addition of chemicals or by other chemical reactions; includes precipitation, adsorption, and disinfection.

Answer 7

Unit Operations, Chemical

Question 8

Treatment methods in which the removal or conversion of constituents is brought about by biological activity; primarily used to remove the biodegradable organic constituents through conversion to cell tissue or gases; also used to remove nutrients (nitrogen and phosphorous).

Answer 8

Unit Operations, Biological

Question 9

That group of bacteria that grow best within the temperature range of 20–40 °C (68–104 °F).

Answer 9

Mesophilic

Question 10

Bacteria which grow best at temperatures between 5 and 75 °C (95 and 167 °F) with optimum growth between 55 and 65 °C (131 and 149 °F).

Answer 10

Thermophilic

Question 11

Bacteria which grow best at temperatures between 10 and 30 °C (50 and 86 °F) with optimum growth between 12 and 18 °C (54 and 64 °F).

Answer 11

Psychrophilic bacteria

Question 12

An organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter.

Answer 12

Heterotroph

Question 13

An organism that utilizes organic and/or inorganic carbon as energy source.

Answer 13

Chemoheterotroph

Question 14

An organism that utilizes light as its source of energy.

Answer 14

Photoautotroph

Question 15

An organism that utilizes inorganic compounds to produce organic compounds such as carbohydrates, fats, and proteins from inorganic carbon dioxide.

Answer 15

Lithoauthotroph

Question 16

Wastewater treatment in which bacteria breakdown waste without using oxygen.

Answer 16

Anaerobic

Question 17

In the presence of, or requiring, oxygen.

Wastewater treatment depending on oxygen for bacterial breakdown of waste.

Answer 17

Aerobic

Question 18

Treatment that implements natural organisms to decompose hazardous materials into less toxic or nontoxic materials.

Answer 18

Bioremediation

Question 19

The destabilization and initial aggregation of colloidal and finely divided suspended matter by the addition of an inorganic coagulant.

Answer 19

Coagulation

Question 20

The provision of retention time with gentle agitation to allow the floc particles or precipitate, associated with the impurities to increase in size by agglomeration. In water and wastewater treatment, the agglomeration of colloidal and finely divided suspended matter after coagulation by gentle stirring by either mechanical or hydraulic means. For biological wastewater treatment in which coagulation is not used, agglomeration may be accomplished
biologically.

Answer 20

Flocculation

Question 21

A common method of disposing of pollutants in wastewaters. In the process, large quantities of air are bubbled through wastewaters that contain dissolved organic substances in open aeration tanks. Bacteria and other types of microorganisms present in the system need oxygen to live, grown, and multiply in order to consume the dissolved organic “food” or pollutants in the waste. After several hours in a large holding tank, the water is separated from the sludge of bacteria and discharged from the system. Most of the activated sludge is returned to the treatment process, while the remainder is disposed of by one of several acceptable methods.

Answer 21

Activated sludge process

Question 22

Aerobic systems where the oxygen required by the heterotrophic bacteria (a heterotroph is an organism that cannot fix carbon and uses organic carbon for growth) is provided not only by transfer from the atmosphere but also by photosynthetic algae.

Answer 22

Aerobic (oxidation) pond

Question 23

Settling of solid material out of a liquid, typically accomplished by reducing the velocity of the liquid below the point at which it can transport the suspended material; may be enhanced by coagulation and flocculation. Separation under the
action of gravity of particles from the fluid in which they are suspended. The process of settling and deposition, under the influence of gravity, of suspended matter carried by water or wastewater.
it is:
(1) The process of subsidence and decomposition of suspended matter or other liquids by gravity. It is usually accomplished by reducing the velocity of the liquid below the point at which it can transport the suspended material. Also called settling. It may be enhanced by coagulation and flocculation.
(2) Solid–liquid separation resulting from the application of an external force, usually settling in a clarifier under the force of gravity. It can be variously classed as discrete, flocculent, hindered, and zone sedimentation.

Answer 23

Sedimentation

Question 24

The process of diverting water from the surface of a stream or conduit by means of a shallow overflow. (2) The process of diverting water from any elevation in a reservoir by means of an outlet at a different elevation or by any other skimming device in order to obtain the most palatable drinking water. (3) The process of removing grease or scum from the surface of wastewater in a tank.

Answer 24

Skimming

Question 25

The seepage of groundwater into a sewer system, including service connections. Seepage frequently occurs through defective or cracked pipes, pipe joints and connections, interceptor access risers and covers, or manhole walls. The downward movement of water through a soil from rainfall or from the application of artificial recharge in response to gravity and capillarity.
(1) The flow or movement of water through the interstices or pores of a soil or other porous medium. (2) The quantity of groundwater that leaks into a pipe through joints, porous walls, or breaks. (3) The entrance of water from the ground into a gallery. (4) The absorption of liquid by the soil, either as it falls as precipitation or from a stream flowing over the surface.
(5) Uncontrolled leakage of air into a building through cracks around doors, windows, electrical outlets and at structural joints. The downward movement of water into the soil. It is largely governed by the structural condition of the soil, the nature of the soil surface including presence of vegetation, and the antecedent moisture
content of the soil.

Answer 25

Infiltration

Question 26

Degradation of water quality due to enrichment by nutrients primarily nitrogen (N) and phosphorus (P), which results in excessive plant (principally algae) growth and decay. Low dissolved oxygen in the water is a common consequence.

Answer 26

Eutrophication

Question 27

Inability of sludge solids to separate from the liquid under quiescent conditions; under aerobic conditions may be associated with the growth of filamentous organisms, low DO, or high sludge loading rates; under anaerobic. Conditions, may be associated with attachment of gas bubbles to solids.
Bulking sludge typically has an SVI. 150 mL/g.

Answer 27

Bulking

Question 28

Biological oxidation of ammonium (NH4+) to
nitrite (NO2−) and nitrate (NO3−), or a biologically induced increase in the oxidation state of nitrogen. The oxidation of ammonia nitrogen to nitrate nitrogen in wastewater by biological or chemical reactions.

Answer 28

Nitrification

Question 29

The anaerobic biological reduction of nitrate nitrogen to nitrogen gas; also, removal of total nitrogen from a system.

Answer 29

Denitrification

Question 30

A device that removes suspended matter such as oil or solids, from water, by dissolving air in the water under pressure and then releasing the air at atmospheric pressure in a flotation tank or basin.

Answer 30

DAF (Dissolved Air Flotation Unit)

Question 31

Component in which batch type suspended
growth (activated sludge) processes are carried out in the same tank in stepwise order (e.g. fill, treat, settle, decant, and draw).

Answer 31

Sequencing batch reactor (SBR)

Question 32

A filter using more than one filtering media (such as coal and sand).

Answer 32

Mixed Media Gravity Filter

Question 33

Relatively large device similar to a septic tank located outside a facility that generates commercial food service wastewater and is designed to intercept, congeal, and retain or remove fats, oils, and grease (FOGs)

Answer 33

Grease trap

Question 34

Usually, in municipal wastewater treatment, a chamber or tank in which primary influent is slowed down so heavy typically inorganic solids can drop out, such as metals and plastics. It is typically a long narrow tank designed to settle out solids such as sand, coffee grounds, and eggshells from wastewater passing through it. A detention chamber or an enlargement of a sewer designed to reduce the velocity of flow of the liquid to permit the separation of mineral (grit) from organic solids by differential sedimentation.

Answer 34

Grit chamber

Question 35

A filter containing filtering media of different

particle size or density.

Answer 35

Mixed-Media Filter

Question 36

(1) Porous material or mesh configured as a
plate or cylinder that allows the passage of particles smaller than particular size, (e.g., an effluent screen) according to a specific flow/ pressure relationship; a screen has area but no depth with respect to flow; (2) Use of a porous material or mesh in order to separate particles by size; screen is a device with openings, generally of uniform size, used to retain or remove suspended or floating solids in flow stream preventing them from passing a given point in a conduit. The screening element may consist of parallel bars, rods, wires, grating, wire mesh, or perforated plate.

Answer 36

Screen

Question 37

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. it is also called settling basin and sedimentation basin. it may also be a tank or basin in which wastewater is held for a period of time during which the heavier solids settle to the bottom and the lighter materials float to the water surface. It is is any large circular or rectangular sedimentation tank used to remove settleable solids in water or wastewater. A special type of it, called an “up-flow”, uses flotation rather than sedimentation to remove solids.

Answer 37

Clarifier

Question 38

A device designed to purify water by making it to pass through a layer of sand. SIt is a bed of sand through which water is passed to remove fine suspended particles. Commonly used in tertiary wastewater treatment plants and sludge drying beds.

Answer 38

Sand filter

Question 39

Constructed basin lined with either soil with very low permeability or a synthetic material, surrounded with berms and which contains at least 3 feet of wastewater which utilizes sunlight, wind or mechanical aeration, and natural bacteria to break down waste via physical, chemical and biological processes to stabilize wastewater; typically consists of two or more basins with operational controls allowing or facilitating flow through the basins.

Answer 39

Wastewater Stabilization Pond

Question 40

Any equipment or process, after gravity sedimentation, that increases the concentration of solids in sludges with or without the use of chemical flocculents.

Answer 40

Thickeners

Question 41

The introduction of earthworms to the filtration systems. It is widely used to treat wastewater and appeared to have high treatment efficiency, including synchronous stabilization of wastewater and sludge.

Answer 41

Vermifilter

Question 42

Heavy, inorganic matter, such as sand or pebbles. Airborne solid particles in the atmosphere or flues. The heavy suspended mineral matter present in water or wastewater, such as sand, gravel, or cinders. It is removed in a pre-treatment unit called a grit chamber to avoid abrasion and wearing of subsequent treatment devices.

Answer 42

Grit

Question 43

The rate at which organisms use the oxygen in water or in wastewater while stabilizing decomposable organic matter under aerobic conditions in decomposition, organic matter serves as food for the bacteria. and energy results from its oxidation.

Answer 43

BOD

Question 44

It is the equivalent amount of oxygen consumed under specified conditions in the chemical oxidation of the organic and oxidisable inorganic matter contained in a wastewater corrected for the influence of chlorides. In American practice, unless otherwise specified, the chemical oxidizing agent is hot acid dichromate. It is used to estimate the amount of organic matter in a sample. It is a measurement of the oxygen equivalent of the materials present in the sample subject to oxidation by a strong chemical oxidant.

Answer 44

COD

Question 45

Is a term used by water quality professionals to describe pollutants that have been detected in water bodies, that may cause ecological or human health impacts, and typically are not regulated under current environmental laws. Sources of these pollutants include agriculture, urban runoff, and ordinary household products (such as soaps and disinfectants) and pharmaceuticals that are disposed to sewage treatment plants and subsequently discharged to surface waters.

Answer 45

Contaminants of emerging concern (CEC)

Question 46

They are chemical substances that persist in the environment as they are resistant to environmental degradation via chemical, biological or photolytic processes. The compounds are known to bioaccumulate through the food web and pose a risk of causing adverse effects to human health and the environment. These include dioxins and furans.

Answer 46

Persistent organic pollutants (POPs)

Question 47

Substances that stop the production or block the transmission of hormones in the body

Answer 47

Endocrine disruptors

Question 48

Chemical substances such as prescription or over-The-counter therapeutic drugs, fragrances, cosmetic, sunscreen agents, diagnostic agents, among others.

Answer 48

Pharmaceutical and personal care products (PPCP)

Question 49

The total amount of solids in solution and suspension. The sum of dissolved and suspended solid constituents in water or wastewater.

Answer 49

Total solids (TS)

Question 50

It is the combined total of all dissolved solids in wastewater, both organic and inorganic and very fine, such as colloidal minerals. Generally, particles must be smaller than two micrometers to be considered a dissolved solid. For example, salt dissolved in water is a dissolved solid. Therefore TDS will “survive” screening or other coarse filtration. The sum of all dissolved solids (volatile and nonvolatile).

Answer 50

Total dissolved solids (TDS)

Question 51

Concentration of all substances suspended in water (solids remaining after filtering of a water sample). The amount of insoluble solids floating and in suspension in the wastewater. Also referred to as total nonfilterable residue.

Answer 51

Total suspended solids (TSS)

Question 52

A quantitative measure of both total inorganic and total organic carbon as determined instrumentally by chemical oxidation to carbon dioxide and subsequent infrared detection in a carbon analyzer.

Answer 52

Total Carbon (TC)

Question 53

Measure of the concentration of organic carbon determined by oxidation of the organic matter into carbon dioxide (CO2) typically expressed in mg/L.

Answer 53

Total organic carbon (TOC)

Question 54

Organic chemicals all contain the element carbon (C). Organic chemicals are the basic chemicals found in living things and in products derived from living things, such as coal, petroleum, and refined petroleum products. Many of the organic chemicals we use do not occur in nature, but were synthesized by chemists in laboratories. Volatile chemicals readily produce vapors at room temperature and normal atmospheric pressure. Vapors escape easily from volatile liquid chemicals. Volatile organic chemicals include gasoline, industrial chemicals such as benzene, solvents such as toluene and xylene, and tetrachloroethylene (perchloroethylene, the principal dry cleaning solvent).
Many volatile organic chemicals, such as benzene, are also hazardous air pollutants. Any compound containing carbon and hydrogen or containing carbon and hydrogen in combination with other elements.

Answer 54

Volatile Organic Compounds (VOCs)

Question 55

Those solids in water, wastewater, or other liquids that are lost on ignition of the dry solids at 550°C for 60 min. Materials, generally organic, that can be driven off from a sample by heating, usually to 550°C (1022°F); nonvolatile inorganic solids (ash) remain.

Answer 55

Volatile Solids

Question 56

(1) A condition in water or wastewater caused by the presence of suspended matter and resulting in the scattering and absorption of light. (2) Any suspended solids imparting a visible haze or cloudiness to water that can be removed by filtration. (3) An analytical quantity usually reported in turbidity units determined by measurements of light scattering.
The cloudy appearance of water caused by the presence of suspended and colloidal matter. In the Handbook on Wastewater Management 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 amount of light reflected by suspended particles. It cannot be directly equated to suspended solids because white particles reflect more light than dark-colored particles and many small particles will reflect more light than an equivalent large particle. Any finely divided, insoluble impurities that mar the clarity of the water. A measure of the clarity of water. Typically is measured by determining light transmission through the water.

Answer 56

Turbidity

Question 57

(1) A salt that contains phosphorus as (PO4)23. (2) A product of hydrolysis of condensed (polymeric) phosphates. (3) A nutrient required for plant and animal growth.

Answer 57

Orthophoshate

Question 58

The amount of water applied to a given treatment process, usually expressed as volume per unit time, or volume per unit time per unit surface area.

Answer 58

Hydraulic loading

Question 59

The organic or volatile suspended solids in the mixed liquor of an aeration tank. The volatile portion is used as a measure or indication of the microorganisms present. That fraction of the suspended solids in activated-sludge mixed liquor that can be driven off by combustion at 550 °C (1022 °F); it indicates the concentration of microorganisms available for biological oxidation.

Answer 59

Mixed Liquor Volatile Suspended Solids (MLVSS)

Question 60

Time during which suspended, aggregated, precipitated, or colloidal substances settle by gravity.

Answer 60

Settling Time

Question 61

Velocity at which subsidence and deposition of settleable suspended solids in wastewater will occur.

Answer 61

Settling Velocity

Question 62

In the activated-sludge process, the loading rate expressed as pounds of BOD5 per pound of mixed liquor or mixed liquor volatile suspended solids per day (lb BOD5/d/lb MLSS or MLVSS).

Answer 62

Food-to-Microorganism (F:M) Ratio.

Question 63

Average residence time of suspended solids in a biological treatment system equal to the total weight of suspended solids in the system divided by the total weight of suspended solids leaving the systems.

Answer 63

Sludge Age

Question 64

The ratio of the volume (in milliliters) of sludge settled from a 1000-mL sample in 30 minutes to the concentration of mixed liquor (in milligrams per liter [mg/L]) multiplied by 1000. This is a calculation used to indicate the tendency of activated sludge solids (aerated solids) in the secondary clarifier to thicken or to become concentrated during the sedimentation/thickening process. To determine it, allow a mixed liquor sample from the aeration basin to settle for 30 minutes. Also determine the suspended solids concentration for a sample of the same mixed liquor. Calculate it by dividing the measured (or observed) wet volume (mL/L) of the settled sludge by the dry weight concentration of MLSS in grams/L. When mixed liquor has an SVI well above 100 mL/gram of solids, it tends to form a thin slurry or billowing sludge blanket or to form bulky sludge.

Answer 64

Sludge Volume Index (SVI)

Question 65

The ratio of the return sludge flow to the wastewater flow.

Answer 65

Return Sludge Ratio (R/Q)

Question 66

The average time of retention of suspended solids in a biological waste treatment system, equal to the total weight of suspended solids leaving the system, per unit time.

Answer 66

Solids Retention Time (SRT)

Question 67

One of the guidelines for the design of settling tanks and clarifiers in treatment plants. Used by operators to determine if tanks and clarifiers are hydraulically (flow) over- or under-loaded. Also called overflow rate.

Answer 67

Surface Loading

Question 68

A design criterion used for sizing clarifiers; typically expressed as the flow volume per unit amount of clarifier space (m3/m2·s [gpd/sq ft]

Answer 68

Surface Overflow Rate

Question 69

The recycled sludge in a (Publicly Owned
Treatment Works) POTW that is pumped from a secondary clarifier sludge hopper to the aeration tank. Settled activated sludge returned to mix with incoming raw or primary settled wastewater. More commonly called return activated sludge.

Answer 69

Return Sludge