|
Absolute
The micron rating of a filter. It indicates that any particle larger than
a specific size will be trapped within the filter.
Absorption
When a solid takes up molecules into its structure.
Acid aerosol
Very small liquid or solid particles that are acidic and are small enough
to become airborne.
Acidic water
Acid neutralizing capacity
Measure of the buffering capacity of water; the ability of water to resist
changes in pH.
Acid rain
Rain that has a flamboyantly low pH, due to contact with atmospheric pollutants
such as sulphuric oxides.
Acidity
The quantitative capacity of water to neutralize a base, expressed in ppm
or mg/L calcium carbonate equivalent. The number of hydrogen
atoms that are present determines this. It is usually measured by titration
with a standard solution of sodium
hydroxide.
Activated coal
This is the most commonly used adsorption medium, produced by heating carbonaceous
substances or cellulose bases in the absence of air. It has a very porous
structure and is commonly used to remove organic matter and dissolved gases
from water. Its appearance is similar to coal or peat. Available in granular,
powder or block form; in powder form it has the highest adsorption capacity.
Activated sludge
Oxygen dependent biological
process that serves to convert soluble organic matter to solid biomass,
that is removable by gravity or filtration.
Active groups
Really fixed ions bolted on to the matrix of an ion exchanger. Each active
group must always have a counter-ion of opposite charge near itself.
Adsorption
Separation of liquids, gases, colloids or suspended matter from a medium
by adherence to the surface or pores of a solid.
Advanced oxidation process
One of several combination oxidation processes. Advanced chemical oxidation
processes use (chemical) oxidants to reduce COD/BOD levels, and to remove
both organic and oxidisable inorganic components. The processes can completely
oxidise organic materials to carbon
dioxide and water, although it is often not necessary to operate the processes
to this level of treatment.
A wide variety of advanced oxidation processes are available:
- Chemical oxidation process using hydrogen
peroxide, ozone, combined ozone & peroxide, hypochlorite, Fenton's
reagent, etc.
- Ultra-violet (UV) enhanced oxidation such as UV/ ozone, UV/ hydrogen,
UV/air
- Wet air oxidation and catalytic wet air oxidation (where air is used
as the oxidant)
Advanced water treatment
The level of water treatment that requires an 85-percent reduction in pollutant
concentration, also known as tertiary treatment.
Advanced Wastewater Treatment
Any treatment of sewage water that includes the removal of nutrients such
as phosphorus and nitrogen
and a high percentage of suspended solids.
Aerated lagoon
A water treatment pond that speeds up biological decomposition of organic
waste by stimulating the growth and activity of bacteria, which are responsible
for the degradation.
Aeration
Technique that is used with water treatment that demands oxygen
supply, commonly known as aerobic biological water purification. Either
water is brought into contact with water droplets by spraying or air is
brought into contact with water by means of aeration facilities. Air is
pressed through a body of water by bubbling and the water is supplied with
oxygen.
Aeration tank
A tank that is used to inject air into water.
Aerobic
A process that takes place in the presence of oxygen,
such as the digestion of organic matter by bacteria in an oxidation pond.
Aerosol
Very small liquid or solid particles dispersed in air.
Affinity
The keenness with which an ion exchanger takes up and holds on to a counter-ion.
Affinities are very much affected by the concentration of the electrolyte
surrounding the ion exchanger.
Agglomeration
A process of bringing smaller particles together to form a larger mass.
Aggressive water
Water that is soft and acidic and can corrode plumbing, pipes and appliances.
Algae
Single- or multi-celled organisms that are commonly found in surface water,
such as duckweed. They produce their own food through photosynthesis. The
algae population is divided up into green algae and blue algae, of which
the blue algae are very damageable to human health. Excessive algae growth
may cause the water to have undesirable odours or tastes. Decay of algae
diminishes oxygen supplies
in the water.
Algal blooms
Periods of enlarged algal growths that affect water quality. Algal blooms
indicate potentially hazardous changes in the chemistry of water.
Alkalinity
Alkalinity means the buffering capacity of water; the capacity of the water
to neutralize itself. It prevents the water pH levels from becoming too
basic or acid. It also adds carbon
to water. Alkalinity stabilizes water at pH levels around 7. However, when
the acidity is high in water the alkalinity decreases, which can cause
harmful conditions for aquatic life.
In water chemistry alkalinity is expressed in ppm or mg/L of equivalent
calcium carbonate. Total alkalinity of water is the sum of all three sorts
of alkalinity; carbonate, bicarbonate and hydroxide alkalinity.
Anaerobic
A process that takes place in the absence of oxygen,
such as the digestion of organic matter by bacteria in a UASB-reactor.
Anion
A negatively charged ion that results from the dissociation of salts, acids
or alkali's in solution.
Anode
A site in electrolysis where metal goes into solution as a cation leaving
behind an equivalent of electrons to be transferred to an opposite electrode,
called a cathode.
Aquatic
Growing in water, living in water, or frequenting water.
Aqueous
Something made up of water.
Aqueous solubility
The maximum concentration of a chemical that dissolves in a given amount
of water.
Aquifer
A layer in the soil that is capable of transporting a significant volume
of groundwater.
Aromatics
A type of hydrocarbon that contains a ring structure, such as benzene and
toluene. They can be found for instance in gasoline.
Assimilation
The ability of water to purify itself of pollutants.
Assimilative Capacity
The capacity of natural water to receive wastewaters or toxic materials
without negative effects and without damage to aquatic life or humans who
consume the water.
Atom
The smallest unit of matter that is unique to a particular element. They
are the ultimate building blocks for all matter.
Atomic number
A specific number that differs for each element, equal to the number of
protons in the nucleus of each of its atoms.
Attrition
The action of one particle rubbing against the other in a filter media
or ion exchange bed that can in time cause breakdown of the particles.
Available chlorine
A measure of the amount of chlorine available in chlorinated lime, hypochlorite
compounds, and other materials.
Backflow
The flow of water in a medium in a direction opposite to normal flow. Flow
is often returned into the system by backflow, if the wastewater in a purification
system is severely contaminated.
Back Pressure
Pressure that can cause water to backflow.
Back siphonage
Reverse seepage of water in a distribution system.
Backwashing
Reversing the flow of water back through the filter media to remove entrapped
solids.
Bacteria
Microscopically small single-cell organisms, that reproduce by fission
of spores.
Bacterial water contamination
The introduction of unwanted bacteria into a water.
Base
An alkaline substance that has a pH that exceeds 7.
Bicarbonates
Salts containing the anion HCO3-. When acid is added, this ion breaks into
H2O and CO2, and acts as a buffer.
Bioaccumulantion
The increase in concentration of a substance in living organisms, as they
take in contaminated air, water, or food, due to slow metabolization and
excretion.
Biochemical Oxygen Demand (BOD)
The amount of oxygen (measured
in mg/L) that is required for the decomposition of organic matter by single-cell
organisms, under test conditions. It is used to measure the amount of organic
pollution in wastewater.
Biocide
A chemical that is toxic to microrganisms. Biocides are often used to eliminate
bacteria and other single-cell organisms from water.
Biodegradable pollutants
Pollutants that are capable of decomposing under natural conditions.
Biofilm
Population of various microrganisms, trapped in a layer of slime and excretion
products, attached to a surface.
Biological contaminants
Living organisms such as viruses, bacteria, fungi, and mammal and bird
antigens that can cause harmful health effects to humans.
Biologically activated carbon
Activated carbon that supports
active microbial growth, in order to aid in the degradation of organics
that have been absorbed on its surface and in its pores.
Biological oxidation
Decomposition of complex organic materials by microrganisms through oxidation.
Biomonitoring
The use of living organisms to test the suitability of effluents for discharge
into receiving waters and to test the quality of such waters downstream
from the discharge.
Bioremediation
The biological treatment of wastewater and sludge, by inducing the breakdown
of organics and hydrocarbons to carbon
dioxide and water.
Biota
All living organisms in a region or ecosystem.
Biotransformation
Conversion of a substance into other compounds by organisms; including
biodegradation.
Blackwater
Water that contains waste of humans, animals or food.
Blind spots
Any place on a filter medium where fluids cannot flow through.
Blinding
A build-up of particles in a filter medium, that prevents fluids from flowing
through.
BOD5
The amount of dissolved oxygen
consumed in five days by bacteria that perform biological degradation of
organic matter.
Boiling point
The temperature at which the vapour pressure of a liquid equals the pressure
of its surface. The liquid will than vaporize If the pressure of the liquid
varies, the actual boiling point varies. For water the boiling point is
100 degrees Celsius.
Bottled water
Water that is sold in plastic containers for drinking water or domestic
use.
Brackish water
Water that is neither falls in the category of salt water, nor in the category
of fresh water. It holds the middle between either one of the categories.
Breakpoint chlorination
Addition of chlorine to water until there is enough chlorine present for
disinfection of water.
Brine
Highly salty and heavily mineralised water, containing heavy metal and
organic contaminants.
Buffer
A substance that reacts with hydrogen
or hydroxyl ions in a solution, in order to prevent a change in pH.
Cake
Solid dewatered residue on a filter media after filtration.
Calcium hypo chlorite
A chemical that is widely used for water disinfection, for instance in
swimming pools or water purification plants. It is especially useful because
it is a stable dry powder and can be made into tablets.
Candle filter
A relatively coarse aperture filter, designed to retain a coat of filter
medium on an extended surface.
Capillary action
Water that at some point rises higher than that portion of its surface,
not in contact with the solid surface. This is due to adhesion, cohesion
and surface tension where later touches a solid.
Cappilary membranes
Membranes about the thickness of a human hair, used for Reverse Osmosis,
nanofiltration, ultrafiltration and microfiltrtion.
Capillary zone
Soil area above the water table where water can rise up slightly through
the cohesive force of capillary action.
Carcinogen
Any dissolved pollutant that can induce cancer.
Cartridge filter
Disposable filter device that has a filter range of 0.1 micron to 100 microns.
Carbonates
Chemical compounds related to carbon
dioxide.
Carbonate hardness
Hardness of water caused by carbonate and bicarbonate by-products of calcium
and magnesium.
Catalyses
Chemical that increases the rate of a reaction but does not take a direct
part in the reaction, so that it is still intact after the reaction has
taken place.
Catch basin
A sedimentation area designed to remove pollutants from runoff before being
discharged into a stream or pond.
Cathode
A site in electrolysis where cations in solution are neutralized by electrons
that plate out on the surface or produce a secondary reaction with water.
Cation
A negatively charged ion, resulting from dissociation of molecules in solution.
Centrifugation
A separation process, which uses the action of centrifugal force to promote
accelerated settling of particles in a solid-liquid mixture.
CFU
Colony Forming Units. This is a measure that indicates the number of microrganisms
in water.
Check valve
A valve that allows water to stream in one direction and will then close
to prevent development of a back-flow.
Chelating agents
Organic compounds that have the ability to draw ion from their water solutions
into soluble complexes.
Chemical Oxygen Demand (COD)
The amount of oxygen (measured
in mg/L) that is consumed in the oxidation of organic and oxidasable inorganic
matter, under test conditions. It is used to measure the total amount of
organic and inorganic pollution in wastewater. Contrary to BOD, with COD
practically all compounds are fully oxidized.
Chemical pollution
Introduction of chemical contaminants into a water body.
Chemical weathering
Dissolving of rock by exposure to rainwater, surface water, oxygen,
and other gases in the atmosphere, and compounds secreted by organisms.
Chloramines
A chemical complex that consists of chlorine and ammonia. It serves as
a water disinfectant in public water supplies in place of chlorine because
chlorine can combine with organics to form dangerous reaction products.
In which forms chloramines exist depends on the physical/ chemical properties
of the water source.
Chlorinated hydrocarbons
Hydrocarbons that contain chlorine. These include a class of persistent
insecticides that accumulate in the aquatic food chain. Among them are
DDT, aldrin, dieldrin, heptachlor, chlordane, lindane, endrin, Mirex, hexachloride,
and toxaphene.
Chlorinated solvent
An organic solvent containing chlorine atoms that is often used as aerosol
spray container, in highway paint, and dry cleaning fluids.
Chlorination
A water purification process in which chlorine is added to water for disinfection,
for the control of present microrganisms. It is also used in the oxidation
of compound impurities in water.
Coagulation
Destabilisation of colloid particles by addition of a reactive chemical,
called a coagulant. This happens through neutralization of the charges.
Coalescence
Liquid particles in suspension that unite to create particles of a greater
volume.
Coastal zone
Lands and waters near the coast, whose uses and ecology are affected by
the sea.
Coliform bacteria
Bacteria that serve as indicators of pollution and pathogens when found
in water. These are usually found in the intestinal tract of humans and
other warm-blooded animals.
Coliform index
A rating of the purity of water based on a count of coliform bacteria.
Colloids
Matter of very small particle size, in the range of 10-5 to 10-7 in diameter.
Combined sewer
A sewer system that carries both sewage and rain water runoff.
Composite sample
A series of water samples taken over a given period of time and weighted
by flow rate.
Compounds
Two or more different elements held together in fixed proportions by attractive
forces called chemical bonds.
Concentrate
The totality of different substances that are left behind in a filter medium
after filtration.
Concentration
The amount of material dissolved in a unit of solution, expressed in mg/L.
Concentration process
The process of increasing the number of particles per unit volume of a
solution, usually by evaporating the liquid.
Condensate
Water obtained by condensation of water vapour.
Condensation
The change of state from a gas to a liquid.
Conductivity
The amount of electricity the water can conduct. It is expressed in a chemical
magnitude. Please use also our information about TDS
and conductivity.
Conduit
A natural or artificial channel through which fluids may be transported.
Contact time
The length of time a substance is in contact with a liquid, before it is
removed by filtration or the occurrence of a chemical change.
Contaminant
Any foreign component in a substance, for example in water.
Conveyance loss
Water loss in pipes and channels by leakage or evaporation.
Cooling tower
Large tower used to transfer the heat in cooling water from a power or
industrial plant to the atmosphere either by direct evaporation or by convection
and conduction.
Corrosivity
Ability of water to dissolve or break down certain substances, particularly
metals.
Cross flow filtration
A process that uses opposite flows across a membrane surface to minimize
particle build-up.
Cryptosporidium
A microorganism in water that causes gastrointestinal illness in humans.
It is commonly found in untreated surface water and can be removed by filtration.
It is resistant to disinfectants such as chlorine.
Current
The portion of a stream or body of water, which is moving much faster than
the rest of the water. The progress of the water is principally concentrated
in the current.
Cycle
The length of time a water treatment unit can be used before it needs cleaning / regeneration, usually
including cleaning / regeneration time.
Dealkalinisation
Any process that serves to reduce the alkalinity of water.
Decarbonation
The process of removing carbon
dioxide from water, using contact towers or air scrubbers.
Decant
To draw off the upper layer of liquid after the heaviest material (a solid
or another liquid) has settled.
Decomposition
The break down of organic matter by bacteria and fungi, to change the chemical
structure and physical appearance of matter.
Defluoridation
The removal of fluoride from drinking water to prevent teeth damage.
De-foaming agents
Chemicals that are added to wastewater discharges to prevent the water
from foaming when it is discharged into a receiving water body.
Degasification
The process of removing dissolved gasses from water, using vacuum or heat.
Deionisation
Process that serves to remove all ionised substances from a solution. Most
commonly is the exchange process where cations and anions are removed independently
of each other.
Demineralisation
Processes to remove minerals from water, usually the term is restricted
to ion exchange processes.
Demiwater
Demineralised water. Water that is treated to be contaminant-, mineral-
and salt free.
enitrification
Removal of nitrate and nitrate product from water to produce a quality
that answeres common water standards.
Density
The weight of a certain amount of water. It is usually expressed in kilograms
per cubic metre.
Depth filtration
Treatment process in which the entire filter bed is used to trap insoluble
and suspended particles in its voids as water flows through it.
Desalination
The removal of salt from seawater or brackish water to produce drinking
water, using various techniques.
Desorption
The opposite of adsorption; the release of matter from the adsorption medium,
usually to recover material.
Detention time
The actual time that a small amount of water is in a settling basin or
flocculating basin. In storage reservoirs, it means the length of time
water will be stored.
Detergent
A water-soluble cleansing agent, other than soap.
Dewater
The separation of water from sludge, to produce a solid cake.
Diffuser
A component of the ozone contacting system in an ozone generator that allows
diffusion of an ozone containing gas.
Diffusion
The movement of gas molecules or aerosols into liquids, caused by a concentration
gradient.
Digester
A closed tank for wastewater treatment, in which bacterial action is induced
to break down organic matter.
Diluting water
Distilled water that has been stabilized, buffered, and aerated. It is
often applied in the BOD tests.
Discharge
Flow of surface water in a stream or canal.
Disinfectants
Fluids or gasses to disinfect filters, pipelines, systems, etc.
Disinfection
The decontamination of fluids and surfaces. To disinfect a fluid or surface
a variety of techniques are used, such as ozone disinfection. Often disinfection
means eliminating the present microrganisms with a biocide.
Dissolve
The process during which solid particles mix molecule by molecule with
a liquid and appear to become part of the liquid.
Dissolved air flotation (DAF)
A procedure of induced flotation with very fine air bubbles or 'micro bubbles',
of 40 to 70 microns.
Dissolved oxygen
The amount of oxygen dissolved
in water at a certain time, expressed in ppm mg/L.
Dissolved solids
Solids material that totally dissolves in water and can be removed by means
of filtration.
Distillation
Water treatment method where water is boiled to steam and condensed in
a separate reservoir. Contaminants with higher boiling points than water
do not vaporize and remain in the boiling flask.
Dredging
Cleaning, deepening, or widening of a waterway, using a machine (dredge)
that removes materials by means of a scoop or a suction device.
Drought
Term applied to periods of less than average precipitation over a certain
period of time.
Effluent
The outlet or outflow of any system that deals with water flows, for an
oxidation pond for biological water purification. It is the product water
of the given system.
Ejector
A device used to inject a chemical solution into water during water
treatment.
Electrical charge
The charge on an ion, declared by its number of electrons. A Cl- ion is
in fact a Cl atom which has acquired an electron, and a Ca++ ion is a Ca
atom, which has lost two electrons.
Electrolyte
Substance that dissociates into ions when it dissolves in water.
Electrodialysis
A process that uses electrical currents, applied to permeable membranes,
to remove minerals from water.
Electrolysis
Process where electrical energy will change in chemical energy. The process
happens in an electrolyte, a watery solution or a salt melting which gives
the ions a possibility to transfer between two electrodes. The electrolyte
is the connection between the two electrodes, which are also connected
to a direct current. If you apply an electrical current, the positive ions
migrate to the cathode while the negative ions will migrate to the anode.
At the electrodes, the cations will be reduced and the anions will be oxidated.
Electrons
Negatively charged building blocks of an atom that circle around the nucleus.
Elements
The distinctive building blocks of matter that make up every material substance.
Emulsifier
A chemical that helps suspending one liquid in another.
Emulsion
Dispersion of one liquid in another liquid, occurs when a liquid in insoluble.
Erosion
The wearing away of the land surface by wind, water, ice or other geological
agents. Erosion occurs naturally from weather or runoff but is often intensified
by human land use practices.
Eschericha coli (E. coli)
Coliform bacterium that is often associated with human and animal waste
and is found in the intestinal court. It is used by health departments
and private laboratories t measure the purity of water.
Evaporation
The process of the passage of water from liquid to vapour.
Evaporation ponds
Areas where sewage sludge is dumped and dried.
Facultative bacteria
Bacteria that can live under aerobic or anaerobic conditions.
Fermentation
The conversion of organic matter to methane, carbon
dioxide and other molecules by anaerobic bacteria.
Filter medium
The permeable material that separates solids from liquids passing through
it.
Filtrate
A liquid that has passed through the filter medium.
Filtration
Separation of a solid and a liquid by using a porous substance that only
lets the liquid pass through.
First draw
The water that comes out when a tap is first opened. It is likely that
is has the highest level of lead contamination from weathering of pipelines.
Fission
Reproduction of microrganisms by means of cell division.
Floc
A flocculent mass that is formed in the accumulation of suspended particles.
It can occur naturally, but is usually induced in order to be able to remove
certain particles from wastewater.
Flocculation
The accumulation of destabilized particles and micro flakes, and subsequently
the formation of sizeable flakes. One must ad another chemical called flocculent
in order to facilitate the formation of flakes called flocs.
Flotation
A solids-liquid or liquid-liquid separation procedure, which is applied
to particles of which the density is lower than that of the liquid they
are in. there are three types: natural, aided and induces flotation.
Flow
The discharge rate of a resource, expressed in volume during a certain
period of time.
Flow augmentation
The addition of water to meet flow needs.
Flux
The rate at which a Reverse Osmosis Membrane allows water to pass through
it.
Fouling
The deposition of organic matter on the membrane surface, which causes
inefficiencies.
Fragmentation
The subdivision of a solid in fragments. The fragments will then adhere
to the nearest surface.
Freezing
The change of a liquid into a solid as temperature decreases. For water,
the freezing point is 0 degrees Celsius.
Freshwater
Water containing less than 1 mg/l of dissolved solids of any type.
Gallon
A unit that is now almost entirely out of date. It is equivalent to 3.785
litres.
Giardia
A microrganism that is commonly found in untreated surface water and can
be removed by filtration. It is resistant to disinfectants such as chlorine.
Granular activated carbon
The heating of carbon to
encourage active sites to absorb pollutants.
Gray Water
Domestic wastewater composed of wash water from kitchen, bathroom, and
laundry sinks and from tubs, and washers.
Groundwater
Water that can be found in the saturated zone of the soil; a zone that
consists merely of water. It slowly moves from places with high elevation
and pressure to places with low elevation and pressure, such as rivers
and lakes.
Groundwater discharge
Ground water entering coastal waters, which has been contaminated by land-fill
leachates, deep well injection of hazardous wastes and septic tanks.
Groundwater hydrology
The branch of hydrology that deals with the occurrence, movements, replenishment
and depletion, properties and methods of investigation and utilisation
of groundwater.
Gully
A deeply eroded channel created by the concentrated flow of water.
Half-life
The time required for a pollutant to lose one-half of its original concentraton.
Hard water
Water that contains a great number of positive ions. The hardness is determined
by the number of calcium and magnesium atoms present. Soap usually dissolves
badly in hard water.
Heat exchanger
A component that is utilized to remove heat from or ad heat to a liquid.
Heavy metals
Metals that have a density of 5.0 or higher and a high elemental weight.
Most are toxic to humans, even in low concentrations.
Heavy water
Water in which all the hydrogen
atoms have been replaced by deuterium.
Henry's Law
A way of calculating the solubility of a gas in a liquid, based on temperature
and partial pressure, by means of constants.
Holding Pond
A pond or reservoir, usually made of earth, built to store polluted runoff.
Humidification
The addition of water vapour to air.
Hydraulic conductivity
The rate at which water can move through a permeable medium.
Hydraulic gradient
In general, the direction of groundwater flow due to changes in the depth
of the water table.
Hydrocarbon
Organic compounds that are built of carbon
and hydrogen atoms and are
often used in petroleum industries.
Hydrogen sulfide (H2S)
A gas emitted during organic decomposition by a select group of bacteria,
which strongly smells like rotten eggs.
Hydrogeology
The science of chemistry and movement of groundwater.
Hydrograph
A chart that measures the amount of water flowing past a point as a function
of time.
Hydrolysis
The decomposition of organic compounds by interaction with water.
Hydrologic cycle
The natural cycle of water passing through the environment, including evaporation,
condensation, retention and run-off.
Hydrophilic
Having an affinity for water.
Hydrophobic
Having an aversion for water.
Hydrosphere
Region that includes all the earth's liquid water, frozen water, floating
ice, frozen upper layer of soil, and the small amounts of water vapour
in the atmosphere.
Hypo chlorite
An anion that forms products such as calcium and sodium
hypo chlorite. These products are often used for disinfection and bleaching.
Hypoxic waters
Waters with dissolved oxygen
concentrations of less than 2 mg/L, the level generally accepted as the
minimum required for life and reproduction of aquatic organisms.
Ice
The solid form of water.
Imhoff cone
A clear, cone-shaped container used to measure the volume of settle able
solids in a specific volume of water.
Immiscibility
The inability of two or more solids or liquids to readily dissolve into
one another.
Impermeable
Not easily penetrated by water.
Impurities
Particles or other objects that cause water to be unclear.
Indicator
Any biological entity or process, or community whose characteristics show
the presence of specific environmental conditions or pollutants.
Indicator organisms
Microrganisms, such as coliforms, whose presence is indicative for pollution
or for the presence more harmful microrganisms.
Indicator tests
Tests for a specific contaminant, group of contaminants, or constituent
which signals the presence of something else.
Indirect discharge
Introduction of pollutants from a non-domestic source into a publicly owned
wastewater treatment system. Indirect dischargers can be commercial or
industrial facilities whose wastes enter local sewers.
Infiltration
Penetration of water into a medium, for instance the soil.
Influent
The stream of water that enters any system or treatment unit.
Inhibitor
chemical that interferes with a chemical reaction, such as precipitation.
Injection
The introduction of a chemical or medium into the process water to alter
its chemistry or filter specific compounds.
Ion
An atom in a solution that is charged, either positively (cations) or negatively
(anions).
Ion exchange
The replacement of undesirable ions with a certain charge by desirable
ions of the same charge in a solution, by an ion-permeable absorbent.
Inorganic chemicals
Chemical substances of mineral origin, not of basically carbon
structure.
Irrigation
Applying water or wastewater to land areas to supply the water and nutrient
needs of plants.
Jar test
A laboratory test procedure with differing chemical doses, mix speeds,
and settling times, to estimate the minimum or ideal coagulant dose required
to achieve water quality goals.
Kinetic Energy
Energy possessed by moving water.
Kinetic rate coefficient
A number that describes the rate at which a water constituent such as a
biochemical oxygen demand
or dissolved oxygen rises
or falls.
Laboratory water
Purified water used in the laboratory as a basis to create solutions or
making dilutions. It contains no interfering substances.
Lagoon
A shallow pond where sunlight, bacterial action, and oxygen
work to purify wastewater.
Lake
An inland body of water, usually fresh water, formed by glaciers, river
drainage, etc. It is usually larger than a pool or pond.
Laminar flow
A flow in which rapid fluctuations are absent.
Langelier Index (LI)
An index reflecting the equilibrium pH of a water with respect to calcium
and alkalinity; used in stabilizing water to control both corrosion and
scale deposition.
Leachate
Water that contains solute substances, so that it contains certain substances
in solution after percolation through a filter or soil.
Leaching
The process by which soluble constituents are dissolved and filtered through
the soil by a percolating fluid.
Leakage
A species of ions in the feed of an ion exchanger present in the effluent.
Light absorption
The amount of light a certain amount of water can absorb over time.
Lime
Common water treatment chemical. Lime can be deposed on walls of showers
and bathrooms, after lime has reacted with calcium to form limestone.
Limnology
The study of the physical, chemical, hydrological, and biological aspects
of fresh water.
Liquid
A state of matter, neither gas nor solid, that flows and takes the shape
of its container.
Mechanical aeration
Use of mechanical energy to inject air into water to cause a waste stream
to absorb oxygen.
Mechanical flotation
A term used in the mineral industry to describe the use of dispersed air
to produce bubbles that measure 0.2 to 2 mm in diameter.
Media
Materials that form a barrier to the passage of certain suspended solids
or dissolved liquids in filters.
Melting
The change of a solid into a liquid.
Membrane
A thin barrier that allows some compounds or liquids to pass through, and
troubles others. It is a semi-permeable skin of which the pass-through
is determined by size or special nature of the particles. Membranes are
commonly used to separate substances.
Mesotrophic
Reservoirs and lakes which contain moderate quantities of nutrients and
are moderately productive in terms of aquatic animal and plant life.
Metabolise
Conversion of food, for instance soluble organic matter, to cellular matter
and gaseous by-products through a biological process.
Microbial growth
The multiplication of microrganisms such as bacteria, algae, diatoms, plankton,
and fungi.
Micron
A unit to discribe a measure of length, equal to one millionth of a metre.
Microrganisms
Organisms that are so small that they can only be observed through a microscope,
for instance bacteria, fungi or yeasts.
Mineral Water
Contains large amounts of dissolved minerals such as calcium, sodium,
magnesium, and iron. Some tap waters contain as many or more minerals than
some commercial mineral waters. There is no scientific evidence that either
high or low mineral content water is beneficial to humans.
Miscibility
The ability of two liquids to mix.
Mist
Liquid particles measuring 40 to 500 micrometers, are formed by condensation
of vapour. By comparison, fog particles are smaller than 40 micrometers.
Mixture
Various elements, compounds or both, that are mixed.
Molecules
Combinations of two or more atoms of the same or different elements held
together by chemical bonds.
Neutralization
The addition of substances to neutralize water, so that it is neither acid,
nor basic. Neutralization does not specifically mean a pH of 7.0, it just
means the equivalent point of an acid-base reaction.
Neutrons
Uncharged building blocks of an atom that play a part in radio-activity.
They can be found in the nucleus.
Nitrification
A biological process, during which nitrifying bacteria convert toxic ammonia
to less harmful nitrate. It is commonly used to remove nitrogen substances
from wastewater, but in lakes and ponds it occurs naturally.
Non-point sources
Diffuse water pollution sources without a specific point of origin. The
pollutants are generally carried off the land by storm water. Common non-point
sources are agriculture and atmospheric disposal.
Non-potable
Water that is unsafe or unpalatable to drink because it contains pollutants,
contaminants, minerals or infective agents.
Nucleus
The center of an atom, that contains protons and neutrons and carries a
positive charge.
Nuisance Contaminant
Constituents in water, which are not normally harmful to health but may
cause offensive taste, odor, color, corrosion, foaming, or staining.
Nutrient
Any substance that promotes growth with living organisms. The term is generally
applied to nitrogen and
phosphorus in wastewater,
but is also applied to other essential and trace elements.
Nutrient Pollution
Contamination of water resources by excessive inputs of nutrients. In surface
waters, excess algal production is a major concern.
Organic matter
Substances of (dead) plant or animal matter, with a carbon-hydrogen
structure.
Osmosis
Water molecules passing through membranes naturally, to the side with the
highest concentration of dissolved impurities.
Outfall
The place where a wastewater treatment plant discharges treated water into
the environment.
Overflow rate
One of the guidelines for design of the settling tanks and clarifiers in
a treatment plant to determine if tanks and clarifiers are used enough.
Oxidation
A chemical reaction in which ions are transferring electrons, to increase
positive valence.
Oxidation pond
A man-made body of water in which waste is consumed by bacteria.
Oxidation-reduction potential (ORP)
The electric potential required to transfer electrons from the oxidant
to the reductant, used as a qualitative measure of the state of oxidation
in water treatment systems.
Oxygen depletion
The reduction of the dissolved oxygen
level in a water body.
Ozone
An unstable oxidizing agent, that consists of three oxygen
atoms and can be found in the ozone layer in the atmosphere. It is produced
by electrical discharge through oxygen
or by specifically designed UV-lamps.
Ozone generator
A device that generates ozone by passing a voltage through a chamber that
contains oxygen. It is often
used as a disinfection system.
Parameter
A variable, measurable property whose value is a determinant of the characteristics
of a system such as water. Temperature, pressure, and density are examples
of parameters.
Particle size
The sizes of a particle, determined by the smallest dimension, for instance
a diameter. It is usually expressed in micron measurements.
Particulate loading
The mass of particulates per unit volume of water.
Parts per billion
Expressed as ppb; a unit of concentration equivalent to the µg/l.
Parts per million
Expressed as ppm; a measure of concentration. One ppm is one unit weight
of solute per million unit weights of solution. In water analysis the ppm
is equivalent to mg/l.
Pasteurisation
The elimination of microrganisms by heat applies for a certain period of
time.
Pathogens
Disease-producing microrganisms.
Percent saturation
The amount of a substance that is dissolved in a solution compared to the
amount that could be dissolved in it.
Percolating water
Water that passes through rocks or soil under the force of gravity.
Periodic chart
Arrangement of elements in order of increasing atomic numbers, created
by a scientist called Mendelejef.
Permeability
The ability of a medium to pass a fluid under pressure.
Persistence
Refers to the length of time a compound stays in the environment, once
introduced.
pH
The value that determines if a substance is acid, neutral or basic, calculated
from the number of hydrogen
ions present. It is measured on a scale from 0 to 14, on which 7 means
the substance is neutral. pH values below 7 indicate that a substance is
acidic and pH values above 7 indicate that it is basic.
Phase
A state of matter. This can be solid, liquid or gaseous.
Photosynthesis
The process of conversion of water and carbon
dioxide to carbohydrates. It takes place in the presence of chlorophyll
and is activated by sunlight. During the process oxygen
is released. Only plants and a limited number of microrganisms can perform
photosynthesis.
Physical and chemical treatment
Processes generally used in wastewater treatment facilities. Physical processes
are for instance filtration. Chemical treatment can be coagulation, chlorination,
or ozon treatment.
Physical weathering
Breaking down of rock into bits and pieces by exposure to temperature and
changes and the physical action of moving ice and water, growing roots,
and human activities such as farming and construction.
Pilot tests
The testing of a cleanup technology under actual site conditions in a laboratory
in order to identify potential problems before implementation.
Pore
An opening in a membrane or medium that allows water to pass through.
Point source
A stationary location from which pollutants are discharged. It is a single
identifiable source of pollution, such as a pipeline or a factory.
Polar substance
A substance that carries a positive or negative charge, for instance water.
Pollutant
A contaminant at a concentration high enough to endanger the life of organisms.
POP's
Persistent Organic Pollutants, complex compounds that are very persistent
and difficultly biologically degradable.
Potable water
Water that is safe for drinking and cooking.
POU-treatment
Point-Of-Use treatment. Water treatment at a limited number of outlets
in a building, for less than the whole building.
Precipitate
An insoluble reaction product in an aqueous chemical reaction.
Precipitation process
The altering of dissolved compounds to insoluble or badly soluble compounds,
in order to be able to remove the compounds by means of filtration.
Pre-treatment
Processes used to reduce or eliminate wastewater pollutants from before
they are discharged.
Primary wastewater treatment
The removal of suspended, floating and precipitated solids from untreated
wastewater.
Process water
Water that serves in any level of the manufacturing process of certain
products.
Product water
Water that has passed through a water treatment plant and is ready to be
delivered to consumers.
Protons
Positively charged building blocks of an atom that are centered in the
nucleus.
Protozoa
Large microrganisms, which consume bacteria.
Pyrogen
Substance that is produces by bacteria and it fairly stable. It causes
fever in mammals.
Qualitative water assessment
Analyses of water used to discribe the visible or aestetic charcteristics
of water.
Quantitative water assessment
Use of analyses of water properties and concentrations of compounds and
contaminants in order to define water quality.
Quicksilver water
A solution of mercury nitrate used in gilding.
Radioactive
Having the property of releasing radiation.
Raw sewage
Untreated wastewater and its contents.
Raw water
Intake water before any treatment or use.
Reaeration
Renewing air supplies in the lower layers of a reservoir in order to raise
oxygen levels.
Recarbonization
Process in which carbon
dioxide is bubbled into treatment water in order to lower the pH.
Receiving waters
A river, lake, ocean, stream or other watercourse into which wastewater
or treated effluent is discharged.
Recharge Area
An area where rainwater soaks through the ground to reach an aquifer.
Recirculation
Recycling water after it is used. Often it has to pass a wastewater purification
system before it can be reused.
Redox
Shortened term for reduction/ oxidation reactions. Redox reactions are
a series of reactions of substances in which electron transfer takes place.
The substance that gains electrons is called oxidising agent.
Reduction
A chemical reaction in which ions gain electrons to reduce their positive
valence.
Regeneration
Putting the desired counter-ion back on the ion exchanger, by displacing
an ion of higher affinity with one of lower affinity.
Reserve Capacity
Extra treatment capacity built into wastewater treatment plants and sewers
to be able to catch up with future flow increases due to population growth.
Reservoir
A natural or artificial holding area used to store water.
Residue
The dry solids remaining after the evaporation of a sample of water or
sludge.
Resolution
The breaking of an emulsion into its individual components.
Reverse Osmosis process
The Reversed Osmosis (RO) process uses a semi-permeable membrane to separate
and remove dissolved solids, organics, pyrogens, submicron colloidal matter,
viruses, and bacteria from water. The process is called 'reverse' osmosis
since it requires pressure to force pure water across a membrane, leaving
the impurities behind.
Safe water
Water that does not contain harmful bacteria, toxic materials, or chemicals,
and is considered safe for drinking.
Safe yield
The annual amount of water that can be taken from a source of supply over
a period of years without depleting that source beyond its ability to be
naturally refilled.
Salinity
The presence of soluble minerals in water.
Sand filtration
Sand filtration is a frequently used and very robust method to remove suspended
solids from water. The filtration medium consists of a multiple layer of
sand with a variety in size and specific gravity. Sand filters can be supplied
in different sizes and materials both hand operated and fully automatically.
Saturation
The condition of a liquid when it has taken into solution the maximum possible
quantity of a given substance.
Scale
The precipitate that forms on surfaces in contact with water as the result
of a physical or chemical change.
Screening
Use of screens to remove coarse floating and suspended solids from sewage.
Secondary treatment
The removal or reduction of contaminants and BOD of effluent from primary
wastewater treatment.
Sedimentation
Settling of solid particles in a liquid system due to gravity.
Sediments
Soil, sand, and minerals washed from land into water, usually after rain.
Semi-confined aquifer
An aquifer partially confined by soil layers of low permeability through
which recharge and discharge can still occur.
Semipermeable
A medium that allows water to pass through, but rejects dissolved solids,
so that it can be used to separate solids from water.
Separation
The isolation of the various compounds in a mixture.
Septic tank
An underground storage tank for wastes from homes not connected to a sewer
line. Waste goes directly from the home to the tank.
Settleable solids
Those suspended solids in wastewater that will settle over a certain period
of time and are removed in that way.
Settling
The process of sinking of a substance sinking in water. This occurs when
the substance does not dissolve in water and its density is larger than
that of water.
Sewage
Waste fluid in a sewer system.
Sewage contamination
The introduction of untreated sewage into a water body.
Sewage sludge
Sludge produced in a public sewer.
Sewerage
The entire system of sewage collection, treatment, and disposal.
Sludge
A semi-solid residue, containing microoroganisms and their products, from
any water treatment process.
Softening
The removal of calcium and magnesium from water to reduce hardness.
Soft water
Any water that does not contain large concentrations of the dissolved minerals
calcium or magnesium.
Solidification
Removal of wastewater from a waste or changing it chemically to make it
less permeable and susceptible to transport by water.
Solubility
The amount of mass of a compound that will dissolve in a unit volume of
water.
Solute
Matter dissolved in a liquid, such as water.
Solvent
Substance (usually liquid) capable of dissolving one or more other substances.
Sparger
A device that introduces compressed air into a liquid.
Sparging
Injection of air below the water table to strip dissolved volatile organic
compounds and to facilitate aerobic biodegradation of organic compounds.
Specific conductance
Method to estimate the dissolved solid content of a water supply by testing
its conductivity.
Spring
Ground water seeping out of the earth where the water table exceeds the
ground surface.
Stoke's Law
A method to calculate the rate of fall of particles through a fluid, based
on density, viscosity and particle size.
Sublimation
The transitions of water directly from the solid state to the gaseous state,
without passing through the liquid state.
Surface tension
The elastic-like force in a body, especially a liquid, tending to minimize,
or constrict, the area of the surface.
Surface water
All water naturally open to the atmosphere, concerning rivers, lakes, reservoirs,
ponds, streams, impoundments, seas, estuaries and wetlands.
Suspended solids
Solid organic or inorganic particles that are held in suspension in a solution.
Synergism
The combined action of several chemicals, which produces a total effect
greater than the effects of the chemicals separately.
Tertiary treatment
Advanced cleaning of wastewater that goes beyond the secondary or biological
stage, removing nutrients such as phosphorus,
nitrogen, and most BOD and
suspended solids.
Thermal pollution
Discharge of heated water from industrial processes in receiving surface
water, causing death or injury of aquatic organisms.
Titration
An analytical technique to determine how much of a substance is present
in a water sample by adding another substance and measuring how much of
that substance must be added to produce a reaction.
TDS
Total Dissolved Solids. The weight per unit volume of water of suspended
solids in a filter media after filtration or evaporation.
TH
Total Hardness. The sum of calcium and magnesium hardness, expressed as
a calcium carbonate equivalent.
TS
Total Solids. The weight of all present solids per unit volume of water.
It is usually determined by evaporation. The total weight concerns both
dissolved and suspended organic and inorganic matter.
Total solids
All the solids in water, including suspended solids
and dissolved solids.
Toxic water pollutants
Compounds that are not naturally found in water at the given concentrations
and that cause death, disease, or birth defects in organisms that ingest
or absorb them.
Transpiration
The process by which water vapour is released into the atmosphere after
transpiring of living plants.
Treatment plant
A structure built to treat wastewater before discharging it into the environment.
Trickling filter
A wastewater treatment unit that contains medium material with bacteria.
The stream of wastewater is trickled over the medium and the bacteria break
down the organic wastes. Bacteria are collected on the filter medium.
THM
Trihalomethanes. Toxic chemical substances that consist of a methane molecule
and one of the halogen elements fluorine,
bromine, chlorine
and iodine attached to three
positions of the molecule. They usually have carcinogenic properties.
Tube settler
Device using bundles of tubes to let solids in water settle to the bottom
for removal by sludge.
Turbidity
A measure of non-transparency of water due to the presence of suspended
matter.
Turbulent flow
A flow that contains may rapid fluctuations.
Ultra-violet oxidation
A process using extremely short wave-length light that can kill micro-organisms
(disinfection) or cleave organic molecules (photo oxidation) rendering
them polarized or ionized and thus more easily removed from the water.
Up-flow
An upward flow of water.
UP-water
Ultra pure water creation demands a specialised way of working. A number
of techniques are used amongst others; membrane filtration, ion exchanges,
sub micron filters, ultra violette and ozone systems. The produced water
is extremely pure and contains none to very low concentrations of salts,
organic/ pyrogene components, oxygen,
suspended solids and bacteria.
UV
Ultra Violet. Radiation that has a wavelength shorter than visible light.
It is often used to kill bacteria and destroy ozone.
Vapour
The gaseous phase of substances such as water.
Vaporize
Conversion of a liquid into vapour.
Venturi
A channel that serves the measurement of water flows.
Viruses
The smallest life forms known, that are not cellular in nature. They live
inside the cells of animals, plants and bacteria and often cause disease.
They are made up of a chromosome surrounded by a protein shell.
Viscosity
The syrupiness of water and it determines the mobility of the water. When
the temperature rises, the viscosity degrades; this means that water will
be less mobile at higher temperatures.
VOC
Volatile Organic Compound. Synthetic organic compounds which easily vaporize
and are often carcinogenic.
Wastewater
The spent or used water from a home, community, farm, or industry that
contains dissolved or suspended matter.
Wastewater infrastructure
The plan or network for the collection, treatment, and disposal of sewage
in a community.
Water monitoring
The process of constant control of a body of water by means of sampling
and analyses.
Water pollution
The presence in water of enough harmful or objectionable material to damage
water quality.
Water quality
The condition of water with respect to the amount of impurities in it.
Water recycling
Using water again for the same or another process step, after a small form
of purification is applied.
Watershed
A land area from which water drains to a particular water body.
Water solubility
The maximum possible concentration of a chemical compound dissolved in
water.
Water table
The surface of groundwater in the soil.
Weir
A spill over device used to measure or control water flows.
Well
A deep hole with the purpose to reach underground water supplies.
Wetland
An area that is saturated by surface water or groundwater, with vegetation
adapted for life under those soil conditions.
Wettability
The relative degree to which a fluid will spread into solid surface in
the presence of other immiscible fluids.
Xenobiotic
Any biological substance, displaced from its normal habitat; a chemical
foreign to a biological system.
Yield
The rate of production of cake from a dewatering device.
Zero discharge water
The principle of “zero discharge” is recycling of all industrial wastewater.
This means that wastewater will be treated and used again in the process.
Because of the water reuse wastewater will not be released on the sewer
system or surface water. |
