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Terms
& Germs
A
| B | C
| D | E
| F | G,
H | I,
J, K, L | M | N
| O | P,
Q | R
| S | T,
U,V | W,
X , Y, Z |
A
Activated carbon
Activated
carbon filters (AC) are effective in reducing certain organic
chemicals and chlorine in water. Water is passed through granular
or block carbon material to reduce toxic compounds as well
as harmless taste- and odour-producing chemicals.
The solid material used in an
activated carbon filter is typically petroleum coke, bituminous
coal, lignite, wood products, coconut shell, or peanut shells,
all of which are sources of carbon. The material is activated
by subjecting it to high temperature (2300 °F) and steam in
the absence of oxygen. This process produces a carbon substance
with many small pores and thus a very large surface area,
which is then crushed to yield a granular or pulverized product
Activated carbon adsorption is
an effective means for reducing organic chemicals, chlorine,
lead, and unpleasant tastes and odors in water.
This treatment can produce water
of more desirable quality than that from some public or private
supplies. Units ranging from simple, manually operated devices
to complex, automatic ones are designed to ensure the reduction
of specific contaminants.
Pour-through and faucet-mounted
units are inexpensive but will treat only small quantities
of water at a time and are not as effective as larger, automatic
units. Because the quantity of carbon contained in a pour-through
or faucet-mounted unit is not large enough to provide extensive
contact with the water, these devices are not recommended
for removal of toxic organic chemicals.
A newly installed device should
be flushed with water, following the manufacturer's instructions.
For pour-through models, water should flow slowly through
the unit to assure adequate contact with the carbon.
Filters should be changed on
schedule to avoid contaminant breakthrough.
Only cold, microbiologically
safe water should be used.
Algal
bloom
Rapid growth of algae in surface waters due to an increase
in nutrients such as nitrogen and phosphorus. see cyanobacteria
Alkalinity
The alkalinity of water is its acid-neutralising capacity,
otherwise known as buffering capacity. It is the sum of the
titratable bases in a sample.
Aluminium
Added at treatment plants to aid in trapping particles for
removal in a process called flocculation.
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B
Backflow
A reverse flow condition created by a difference in water
pressures that causes water to flow back into the distribution
pipes of a drinking water supply from any source other than
the intended one.
Backwash
The processes of cleaning by forcing air and water upwards
through a filter which flushes out the trapped material in
the filter.
Biodegradable
A substance that can be broken down into harmless products
in the environment.
Biochemical Oxygen Demand (BOD)
The amount of oxygen used by micro-organisms to break
down organic matter.
Biological nutrient removal
The removal of nutrients, such as nitrogen and phosphorous,
by a natural treatment process involving microorganisms.
Biosolids
Solids from wastewater treatment that have been processed
into products suitable for beneficial use for purposes such
as agriculture or forestry.
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C
Catchment
The area drained by a stream, lake or other body of water.
Frequently used to refer to areas which feed into dams. May
also refer to areas served by a sewerage or stormwater system.
Chlordane
An organochlorine pesticide used to treat termites.
Chlorination
The application of chlorine to drinking water, wastewater,
or industrial waste to disinfect or to oxidise undesirable
compounds.
Chlorine
An additive used to ensure that water is potable. Chlorine
is added, usually by water authorities, to the water supply
at point of treatment. The purpose of this is to kill micro-organisms
that may pass through the treatment plant.
Chlorine dioxide is a strong
oxidizing agent used as a disinfectant and to control taste
and odour. Chlorine dioxide rapidly decomposes into chlorite,
chloride, and chlorate.
See "Chlorine
- our deadly friend"
Coagulation
The addition of a coagulant chemical (eg ferric chloride,
aluminium) to destabilise the charges of a particulate suspended
in water, collapsing the negatively charge "cloud"
surround the particle, so they can agglomerate.
Cryptosporidium
It was an outbreak of cryptosporidium in Sydney that effectively
shut down the water supply and cost Sydney Water about $75
million in compensation to businesses.
Cryptosporidium exists as a resilient,
infectious, round oocyst about four to six microns in diameter.
The cyst is a "casing" for the infectious material
inside.
When ingested, the Oocysts pass
through the stomach into the small intestine. There the Oocysts
split open, releasing sporozoites which invade the cells lining
the gastrointestinal tract.
The Cryptosporidium infection
causes an illness called cryptosporidiosis. Disease
symptoms include diarrhea, abdominal cramps, nausea, occasional
vomiting and low grade fever.
Cryptosporidiosis usually lasts
10 to 14 days. However, it may linger off and on for up to
30 days and can persist for extended periods. Children may
be the most susceptible, particularly six year olds and under.
Cryptosporidiosis may cause complications
for those with illnesses or conditions such as diabetes, alcoholism,
or pregnancy. The effects of prolonged diarrhea and dehydration
can be dangerous, especially for the very young, the elderly,
and the frail.
A rapid cure for Cryptosporidiosis
has not been found. Recovery depends on the patient's overall
health and immune system. The disease can be fatal for those
who are already in a fragile state such as someone with AIDS
or any others weakness to their immune system
Cyanobacteria
(blue-green algae)
Blue-green
algae, known as cyanobacteria, are naturally occurring components
of all freshwater environments When conditions are favourable,
blue-green algae populations can 'bloom', multiplying at such
a rate that they dominate the local aquatic environment.
At this point, problems for other
organisms start to occur. The water begins to stink and a
green scum may appear on the surface. Some species of blue-green
algae produce toxins which are dangerous – sometimes fatal
– to livestock, wildlife, marine animals and humans.
The blue-green algae contain
toxins that affect human and animal health
First, blue-green algae
likes abundant phosphorus and nitrogen. These two nutrients
enter Australia's waterways in large amounts from factories
and sewerage outlets, and as run-off from farms and suburban
parks and lawns. This process is known as eutrophication.
Much of the phosphorus and nitrogen comes from ordinary household
detergents.
Blue-green algae are favoured
by long periods of sunlight which provide warm temperatures
and the energy for photosynthesis.
They also enjoy still, calm conditions.
Such conditions are usually present in dams and reservoirs,
but they can also occur in rivers during drought or when their
flow is reduced by irrigation and household use. The flow
of many river systems in Australia can sometimes be too low
to prevent algal blooms.
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D
Dechlorination
A process that neutralises the toxicity of chlorine and chloramines
(a by-product of chlorine).
Disinfection
Inactivation (killing) of pathogens or organisms, capable
of causing infectious disease, by chemical or physical processes.
Dissolved
oxygen
The amount of oxygen that is dissolved in water.
Distillation
Is when water
is boiled and converts to vapour or steam. The water vapour
is collected either in a condenser or simply on an angled
surface from where it is transported (drips) into a container
and cools reverting to water again. The re-collected water
leaves behind particles (those that aren't volatile)
Drinking
Water
Drinking water is defined as water intended primarily
for human consumption but which has other domestic uses. see
potable water
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E
E.
coli (Escherichia coli)
Faecal bacteria found in the digestive tract of animals,
which are used to indicate presence of wastewater contamination
within an environment.
Effluent
Liquid flowing out.
Effluent
reuse
Effluent reuse is a process where treated wastewater is
recycled for useful purposes and is not discharged to a natural
waterway. The treated water may be used in industry, for golf
courses or to water plants.
Enterococci
Faecal organisms used as an indicator of sewage contamination
in the environment.
Evaporation
Liquid water from the rivers, dams and oceans is converted
by the sun to water vapour which rises back into the atmosphere
as a gas through a process called Evaporation.
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F
Faecal
coliform
Bacteria which inhabits the intestines of humans and other
mammals and are present in faeces. Often used to detect or
measure sewage pollution.
Filtration
A process for removing particles from a solution by passing
it through a porous structure or medium, such as a screen,
membrane, sand or gravel.
Flocculation
The bridging of flocculant chemicals between agglomerated
particles for larger settleable flocs. see Aluminium.
Fluoride
Also added
by some water authorities to the water supply to reduce tooth
decay. More on Fluoride here
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G
Giardia
Giardia is a microscopic parasite that can be found in
water. Giardia causes an intestinal illness called giardiasis
Cryptosporidium is responsible for a similar illness
called cryptosporidiosis.
See above: "Cryptosporidium"
Grey water
Domestic wastewater from sources other than toilets -
for example, water from washing machines and dishwashers.
Groundwater
Water that is found below the surface, usually in porous rock
or soil or in underground aquifers.
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H
Headloss
The difference in head pressure between the top of a filter
and the bottom.
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I
Infiltration
Water entering the water/sewerage system through cracked
pipes or faulty joints.
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M
Manganese
This occurs quite naturally in water from rivers and reservoirs.
It is an essential element in our diet but causes staining
of kettles, baths and laundry.
Megalitre
Measurement of volume equal to one million litres. One
megalitre is approximately the volume of a one metre deep
Olympic-sized swimming pool.
Microfiltration
A pressure-driven membrane operation in which very fine
particles or other suspended matter are separated from a liquid.
Microfiltration is capable of removing suspended solids, bacteria
or other impurities. Membrane pore sizes are slightly larger
than those used for ultrafiltration.
Microorganisms
The organisms which are invisible or only barely visible
with the unaided eye.
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N
Nitrates
Usually found
in private water supplies. Mainly affects bore or well water
and that from rivers and streams, dams etc. Nitrates alone
are harmless, it's when they convert to nitrites that
it becomes dangerous. Babies are most at risk 'blue baby syndrome'
is where the nitrites decrease the bloods ability to transport
oxygen.
Non-potable
reuse
The use of treated wastewater for purposes that do not
require water of a drinkable standard.
Nutrients
Compounds required for growth by plants and other organisms.
Major plant nutrients are phosphorus and nitrogen.
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O
Odour
scrubber
A device for removing odours released during wastewater
treatment.
Organic
Of animal or vegetable origin.
Organism
Any living animal or plant.
Organochlorine
pesticide
An organic compound containing chlorine. They are not
easily broken down and can persist in the environment for
a long time. Includes chlordane, dieldrin and aldrin which
have been banned in some Australian states.
Organophosphate
pesticide
Pesticides which are made up of hydrocarbon compounds
which contain phosphorus, for example, chlorpyrifos and parathion.
They are best known for their ability to persist in the environment,
however, they degrade in the environment faster than organochlorine
pesticides.
Ozonation
The use of ozone for water purification.
Ozone
Ozone (O3),
one of natures basic elements, it is a very powerful disinfecting
and deodorizing gas consisting of oxygen (O2) with an extra
oxygen atom attached, therefore becoming ozone (O3).
When oxygen in the air is exposed to high intensity ultraviolet
rays, ozone is created
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P
Pathogens
Disease-causing organisms, such as bacteria and viruses.
Phosphorus
(P)
An element that is essential for all living organisms.
It is a nutrient and a common ingredient in fertilisers and
washing detergents (to attach to and remove dirt). The Australian
environment is adapted to very low levels of P in soils and
water.
pH
At any given temperature the intensity of the acidic or
basic character of a sample in indicated by pH. Also known
as the hydrogen ion activity in a substance (eg. water, soil,
etc.)
Potable
Water
Potable (NO
not portable) is the term used to describe water
that is safe to drink. That is, water that has been treated
and tested to ensure that it is microbiolcically safe to drink
In Australia, the key reference
material is a document called Australian Drinking Water
Guidelines. These guidelines state:
"Ideally, drinking
water should be clear, colourless, and well aerated, with
no unpalatable taste or odour, and it should contain no suspended
matter, harmful chemical substances, or pathogenic micro-organisms".
In other words, drinking
water needs to be free of chemicals and organic substances
that may be harmful to human health and free of organisms
capable of causing human disease.
The guidelines also
define drinking water as water "·which, on the current
state of knowledge, is safe to drink over a lifetime: that
is, it constitutes no significant risk to health".
This is called potable
water.
Potable
reuse
Reuse of highly treated wastewater for drinking.
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R
Residuals
The area on a treatment plant where the waste generated
by backwashing is processed. It can also refer to the waste
material itself.
Reverse
osmosis
In the reverse
osmosis process a cellophane-like membrane separates purified
water from contaminated water.
Water pressure applied to the
concentrated side, (below) forces the process of osmosis (basically,
the equalising of the particles in the water) into reverse.
Under enough pressure, pure water is squeezed through the
membrane from the concentrated to the dilute side. Salts dissolved
in water as charged ions are repelled by the RO membrane.
Treated water is collected in a storage container. The rejected
impurities on the concentrated side of the membrane are washed
away in a stream of wastewater, not accumulated as on a traditional
filter.
The RO membrane also
functions as an ultra-filtration device, screening out particles,
including microorganisms, that are physically too large to
pass through the membrane’s pores. RO membranes can remove
compounds in the 0.0001 to 0.1 micron size range (thousands
of times smaller than a human hair).
OR
A process in which,
if pressure is put on the concentrated side of a liquid system
in which liquids with different concentrations of mineral
salts are separated by a semi-permeable membrane, molecules
of pure water pass out of the concentrated solution to the
weak or fresh-water side. The reverse osmosis membrane is
permeable to the solvent but impermeable to most dissolved
species, both organic and inorganic.
Two Basic Types:
Reverse Osmosis systems usually have one of two types of membrane,
CTA or TFM. Each of these membranes has a particlar characteristic
and performance.
CTA : Cellulose Tri Acetate
Generally, CTA membranes are used on chlorinated water supplies
with a Total Dissolved solid content below 800 ppm.
TFM : Thin Film membrane
Reverse Osmosis systems fitted with Thin Film composite (TFM)
membranes are idealy used on non chlorinated water supplies
with a higher TDS content. They are also used on chlorinated
supplies where a faster water production is required or a
higher water purity is needed. When used on chlorinated water
supplies an Activated Carbon prefilter is included to remove
the chlorine prior to it entering the membrane.
Risk assessment
Process of gathering data and making assessments to estimate
short and long-term harmful affects on human health or the
environment from exposure to hazards associated with a particular
product or activity.
Runoff
Water that flows across the land surface and does not
soak into the ground.
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S
Sediment
Soil or other particles that settle to the bottom of lakes,
rivers, oceans and other waters/filters.
Sedimentation
A treatment process which allows sediment to settle out
of water or wastewater.
Septic
tank
Underground tank used for treatment of wastewater through
bacterial activity.
Sewage
The wastewater from homes, offices, shops, factories and
other premises discharged to the sewer. About 99 per cent
of sewage is water.
Sewage
overflow (ORG)
A release of sewage from a designed relief point to avoid
sewage flowing back into houses.
Sewerage
system
The network of pipes, pumping stations and treatment plants
used to collect, transport, treat and discharge sewage.
Stormwater
Rainwater which runs off the land, frequently carrying
various forms of pollution such as rubbish, animal droppings
and dissolved chemicals. This untreated water is carried in
stormwater channels and discharged directly into creeks, rivers
and the ocean.
Stormwater
system
The system of pipes, canals and other channels used to
carry stormwater to bodies of water, such as rivers or oceans.
The system does not usually involve any treatment.
Suspended
solids
Particles in water that can be removed by sedimentation
or filtration.
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T
Total
Dissolved Solids
Dissolved salts in water.
Turbidity
The cloudy or muddy appearance of water which is an indication
of fine solids suspended in the water; this is usually measured
by a light penetration test.
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U
Ultrafiltration
High level filtration used for water and wastewater treatment.
This method uses very fine pore size membranes which allows
selective particles to pass through. Capable of removing suspended
solids, bacteria and viruses. Membrane pore sizes are slightly
smaller than those used for microfiltration.
Ultra-Violet
Ultraviolet
(UV) rays are part of the light that comes from the sun. The
UV spectrum is higher in frequency than visible light and
lower than x-rays. As a water treatment technique, UV is known
to be an effective disinfectant due to its strong germicidal
(inactivating) ability. UV disinfects water containing bacteria
and viruses but does not affect Giardia lamblia or Cryptosporidium
cysts.
UV radiation has disinfection
properties that inactivate bacteria, viruses, and some
other microorganisms..
In a typical UV system,
approximately 95 percent of the radiation passes through a
special quartz glass sleeve and into the untreated water that
flows in a thin film over the lamp. The glass sleeve keeps
the lamp at an ideal temperature of 104 °F. UV radiation affects
microorganisms by altering the DNA in the cells and impeding
reproduction. UV treatment does not remove organisms
from the water, it merely inactivates them. Since lamp intensity
decreases over time with use, lamp replacement is a key maintenance
consideration with UV disinfection.
Either sediment filtration
or activated carbon filtration should take place before water
passes through the unit. Particulate matter, color,
and turbidity affect the transmission of light to the microorganisms
and must be removed for successful disinfection.
UV is often the last device in
a series of treatment devices. Following reverse osmosis,
water softening, or filtration. The UV unit should be located
as close as possible to the point-of-use since any part of
the plumbing system could be contaminated with bacteria.
- UV disinfection does not add
chemicals to the water
- UV is effective against bacteria
and viruses; not effective against Giardia lamblia or Cryptosporidium
- UV disinfection has no residual
disinfection
- UV often last device in a
series of water treatment devices
- Regular maintenance and lamp
replacement is essential
UV water treatment is
an effective way to disinfect home drinking water supplies;
it is becoming increasingly popular as an alternative to chlorine
disinfection systems because it adds no chemicals to the water.
There are, however, specific water quality parameters that
must be met for the UV system to produce adequate amounts
of bacteriologically safe water.
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W
Wastewater
Another name for sewage.
Water
filtration plants (WFP)
Water filtration plants are treatment facilities that
improve water quality. Impurities are removed through a process
known as filtration, incoming water is passed through a porous
structure or medium, such as a screen, membrane, sand or gravel.
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