Wastewater Engineering Terminologies

Cake

The dewatered solids coming out from a dewatering device

Standard Jar Test

easiest method to use testing standard volume of sludge with different conditioner concentrations followed by rapid mixing flocculation and settling

Composite Sampling

is a mixture of grab samples over a period of time, with the volume of individual samples usually being proportional to the flow at the time the sample is taken

Grab Sampling

Sample is taken at random with no particular time

Biodegradability Index

is the ratio of BOD5 to COD

Paint Filter Test

it measures the leaching characteristics of screenings

Hydrolyzed

it means that a chemical reaction has happened whereby water reacts with a compound to produce other compounds

Trophy

is defined as the rate at which organic matter is supplied to lakes both from the watershed and through internal production

Mixed Liquor Suspended Solids

the concentration of suspended solids in activated sludge

Mixed Liquor

the mixture of activated sludge and the wastewater

Biosolids

The end products of wastewater sludge treatment process also called treated or stabilized sludge

Sludge

refers to concentrating impurities into solid form and then separating these solids from the bulk liquid

Scum

Floatable materials skimmed from the surface of primary and secondary settling tanks and from grit chamber and chlorine contact tank

Grit

Heavier inorganic solids that settle with relatively high velocities

Normal Flocs

a balance between floc forming and filamentous bacteria results in strong flocs that keep their integrity in the aeration basin and settle well in the sedimentation tank

Specific Oxygen Uptake Rate (SOUR)

is the combination of OUR with MLVSS.

Poly-P bacteria

phosphorous accumulating organisms used in biological phosphorous removal units

Denitrifying bacteria

are facultative anaerobic bacteria that use nitrate in the absence of free molecular oxygen to degrade soluble cBOD

Filamentous Bacteria

cause the sludge not to settle properly a condition called bulking which causes clouds of billowing sludge rather than settling

VFA

are fatty acids containing six or less carbon atoms

Viscous Bulking

is caused by an excessive amount of extracellular bio polymer which produces a sludge with slimy jellylike consistency

Beggiatoa

is a white or a colorless filamentous organism and is associated more commonly with fixed film system process

Activated Sludge

sludge particles in wastewater by the growth of organism in the aeration tank

approximately 95% bacteria and 5% higher organism

Acinetobacter

store large amounts of phosphate under aerobic conditions and releases it under aerobic condition so, they are useful in phosphate removal

Foaming or Frothing

is the condition describing a build up of foam or froth on the surface of the aeration tank

Straggler floc

light fluffy small particles, small, almost transparent, very fluffy, buoyant solids particles

Pin Point Floc

small dense particles less than 1/32 inch diameter of floc due to old sludge that is breaking down

Carbonaceous BOD removal

biological conversion of the carbonaceous organic matter in wastewater to cell tissue and various gaseous end product.

Activated Sludge Process

a biological wastewater treatment process which speeds up waste decomposition

Mean Cell Residence Time

is the average amount of time that microorganism are kept in the system

Anoxic Microorganisms

a group of facultative anaerobs called dentrifiers utilizes nitrite and nitrates as the terminal acceptor

Supernatant

the liquid that is removes from settled sludge, commonly refers to the liquid between the sludge on the bottom and the scum on the surface

Substrate

the term used to denote the organic matter or nutrients that are converted during biological treatment or that may be limiting in biological treatments

Package Plant

pre-manufactured treatment facility small communities or individual properties use to treat wastewater

Flocculation

agitating wastewater to induce the small, suspended particles to bunch together into heavier particles and settle out

Food to microorganisms ratio

is a process control test calculation based on maintaining a specified balance between available food materials BOD or COD in the aeration tank varies 0.5 to 1.0

Enzymes

are organic catalysts produced by the living cell.

Aerotolerant Anaerobs

have a strictly fermentive metabolism but are relatively insensitive to the presence of molecular oxygen

True Facultative Anaerobes

can shift from fermentive to aerobic respiratory metabolism

Anoxic

the use of nitrite or nitrate for electron acceptor under anaerobic conditions

Biochemical Pathways

a series of linked biochemical reactions that occur in a step-wise manner leading from a starting material to an end product

Metabolite

is any molecule that is a nutrient an intermediary product or an end product in a metabolic reaction

Anoxic Denitrification

the process wherein nitrite nitrogen is converted to nitrogen gas in the absence of oxygen

Maturation Ponds

also known as polishing ponds since they are used for polishing effluents from other biological processes

Polyelectrolytes

organic macro molecules having change sites on them to appear, to attach to sludge particles and bridge the smaller particles so that the larger flocs are formed

Pressure filter press

consists of vertical plates that are held rigidly in a frame and pressed together between fixed and moving ends

Filtrate

water coming out from sludge after being squeezed between two belts

Belt filter press

it is a continuous feed sludge dewatering device that involve the application of chemical conditioning gravity drainage and mechanically applied pressure to dewater sludge

Total Nitrogen

is the sum of TKN and nitrate nitrogen or nitrite nitrogen

Total Kjeldhal Nitrogen

is a measure of the total organic and ammonia nitrogen in wastewater

COD

can be conducted in 3 hrs. it is the amount of dissolved oxygen required to oxidize and stabilize organic and inorganic content of the sample solution

Ultimate BOD

is the amount of oxygen demand required to decompose all of the organic material after infinite time

Dissolved Oxygen

it is a measure of how much oxygen is dissolved in a water sample

BOD

the oxygen required by biochemical processes to completely aerobically decompose organic matter

Flagellates

are free swimmers and predominate in light mixed liquors during high food to microorganism conditions

Sludge Blanket

is the accumulation of settled sludge in the clarifier

Return Sludge

the purpose of this is to maintain a sufficient concentration of activated sludge in the aeration tank so that the required degree of treatment can be obtained

Hydraulic Detention Time

refers to the duration or time a wastewater is retained in a reactor

Hydraulic Load

this refers to the amount of water entering the aeration tank

Screenings

include all types of organic and inorganic materials large enough to be removed on bar racks

MLVSS

the fraction of the suspended solids in activated sludge mixed liquor that can be driven off by

combustion at 550 Celsius which indicates the concentration of microorganism available for biological oxidation

Flowsheet

is a graphical representation of a particular combination of unit operation and processes

Break Point Chlorination

ammonia nitrogen is oxidized to nitrogen gas by this process in a mixing basin

Reverse Osmosis

it is a demineralization process applicable to production of high quality water from effluent

Infiltration

is the ground water entering sewers and building connections through defective joints and broken or cracked pipe and manholes

Continuous Sampling

sample represents diversion of a small fraction of the total flow over some period

Surfactants

large organic molecules that are slightly soluble in water and cause foaming in wastewater treatment plants

Turbidity

a measure of the light transmitting properties of water

Nessler Tubes

Comparison Tubes for turbidity

Fixed Solids

rough measure of the mineral content of watewater

Volatile Suspended Solids

solids lost on ignition heating to 550 Celsius

gives a rough approximation of the amount of organic matter present in the solid fraction of wastewater

Total Dissolved Solids

solids in water that can pass thru a standard glass fiber filter also called non filterable solids

Synthesis

a process wherein microorganisms derive energy from carbonaceous organic matter in aerated wastewater

Bulking

is a condition wherein the sludge forms clouds in the secondary clarifier

Settleable Solids

are approximate measure of the quantity of solids that will be removed by sedimentation

Total Suspended Solids

solids in water that can be trapped or retained also called as filterable solids, 70% organic and 30% inorganic

Volatile Solids

the weight loss after a sample is ignited to dryness at 550 Celsius

Total Solids

is defined as all the matter that remains as residue upon evaporation at 103 to 105 degree Celsius

Rotary Drum thickeners

function similarly to the gravity belt where free water from a flocculated sludge drains through a rotating cylindrical stainless steel screen

Gravity belt thickener

the sludge is conditioned with polymer and fed into a feed distribution box at one end where the sludge is distributed evenly across

Process loading rate

key criteria used as basis for siting the individual unit operation and processes

Inflow

is water discharged into sewer pipes or service pipe connections from sources such as roof leaders

Point sources

identifiable source of pollution occur when harmful substances are emitted directly

Load

refers to the mass flux of a pollutant

Sludge thickening

synonymous to sludge concentration

a procedure used to increase the solids content of a sludge

Solid balance

determined by identifying the quantities of solids entering and leaving each unit operation

Co-settling thickening

can be used as sludge thickener and a clarifier

Sludge volume Ratio

volume of the sludge blanket held in the thickener divided by the volume of the thickened sludge removed daily

Gravity thickening

uses gravity forces to separate solids from the sludge

Flotation thickener

is achieved by releasing fine air bubbles that attach to sludge particles and cause them to float

Bulking agent

is an organic or inorganic material used to provide structural support and to increase the porosity of the mixture for effective aeration

Amendment

is an organic material added to the feed substrate primarily to reduce the bulk weight and increase the air voids for proper aeration

Sludge Stabilization

synonymous to Sludge digestion, converting the organic solids to more refractory forms

Sludge Drying Beds

remove moisture by natural evaporation, gravity or induced drainage

Composting

a process in which organic material undergoes biological degradable to a stable end product

Equalization basin

maintains a constant volumetric flow of wastewater from pre-treatment to other downstream operation

Grit chamber

an enlarged channel where the velocity of wastewater is controlled to allow only the heavier solids to settle out

Plant Layout

is the spatial arrangement of the physical facilities of the treatment plant in the flowsheet

Hydraulic profiles

used to identify the elevation of the free surface of the wastewater

Chain of Custody

defined as the unbroken trail of accountability that ensures the physical security of samples, data and records