Fundamental properties of water and Methods of

PurificationPresented by:

Becky LaceyWater purification specialist

History of WaterWhere it comes fromImpuritiesVariations around the countryMethods of water purificationSummaryUseful terminology

Content

History of Water• The Indus Civilisation, which produced the

first cities around 2500BC, also built the first sewers. They even had man hole covers so they could be cleaned and unblocked

• Jerusalem in the 7th Century BC was supplied by a man-made underground water tunnel which led from a protected spring outside the walls

History of Water• The Roman Empire was famous for

building aqueducts to bring water to its cities. Everyday the people of Rome used more than 1000 million litres of water for all uses including fountains and baths. Few homes had piped water though. People carried their waste to sewage disposal points, which led to the Greater sewer or Cloaca Maxima

History of Water

• The Inca Empire provided homes for about 12 million people. To keep people healthy a stone channel ran down each street in the main city carrying fresh water from the mountains, ready to flush away sewage

• The Ashanti Kingdom in 18th century West Africa was very clean. Buildings in the capital had sewage pipes cleaned on a daily basis with boiling water and remote villages had public toilets

History of WaterIn the UK

• 1300 – 1600 – Lead pipes were laid, various methods employed to transport water to cities and towns around the country. By the end of the 1500’s filtration water started to take place.

• 1600 – 1800 – The first flushing toilets were designed and introduced.

• 1800 – 1900 – Mechanical and sand filtration were perfected. 1847 it was a criminal offence to pollute drinking water. 1852 The General Board of Health recommended new sewers in every town. Between 1832 – 1847 there were Cholera Epidemics which lead to 1858 –The year of the “Great Stink” seeing the recommendation of 1852 carried out. 1885 water was checked fro bacteria for the first time. Reservoirs were built around the country.

History of WaterIn the UK

• 1900 – present day The routine way to treat water was to: Screen to catch branches, solids and dead animals, treat it with aluminium sulphate to remove solids and chlorinate against bacteria. 1945 the Water Act reorganised the water industry. 1973 the water bill for England and Wales created 10 Regional Water Authorities. 1989 The Water Act allowed local authorities to sell off the water companies

Water Companies• Anglian Water• Bournemouth and West

Hampshire Water• Hampshire Water• Bristol Water• Cambridge Water• Cholderton and District Water• Dee Valley Water• Dwr Cymru (Welsh Water)

• Essex and Suffolk Water• Folkstone and Dover Water• Mid Kent Water• Northumbrian Water• Portsmouth Water• Scottish Water• Severn Trent Water• South Staffordshire Water

South East Water

Definition of water

The chemical symbol for water is H2O

Definition of waterThe chemical symbol for water is H2O

As a chemical it is defined as Dihydrogen Oxide and therefore it is a binary compound that occurs at room temperature as a clear, colourless, odourless liquid.

Dihydrogen Oxide freezes at 0°C and boils at 100 °C At atmospheric temperatures and pressures it can exist in all three of it’s phases:

Solid (Ice)Liquid (Water)Gaseous (Water vapour / steam)

The Water Cycle

1 = Precipitation2 = Condensation3 = Transpiration4 = Evaporation5 = Surface run off

Impurities of Water

• In solution• In suspension• Gases

Impurities in SolutionAn Inorganic compound is any substance in which two or more chemical elements other than carbon are combined.

Picture = Calcium carbonate crystals

Organic compound are substances whose molecules contain one or more (often many more) carbon atoms

Impurities in Suspension

Living matter which will include any plant, animal or bacteria

Colloids are substances inorganic or organic which are finely dispersed throughout the liquid medium of water.Particle size is usually between 1-100nm.

Gases

Carbon Dioxide - CO2

Oxygen - O2

Sulphur Dioxide – SO2

Chlorine – Cl2

Water Sources for England and Wales

Prescribed Concentration or Value (PCV)

250 mg/lCalcium

5 µg/lCadmium

2000 µg/lBoron

1000 µg/lBarium

50 µg/lArsenic

10 µg/lAntimony

0.5 mg/lAmmonium

200 µg/lAluminium

No standardAlkalinity

Amount AllowedChemical parameters

0 per 100 mlTotal coliforms

0 per 100 mlFaecal coliforms, faecal streptococci, Clostridium perfringens

Amount AllowedMicrobiological parameters

StandardSubstance

50 µg/lNickel

1 µg/lMercury

50 µg/lManganese

50 mg/lMagnesium

50 µg/lLead

200 µg/lIron

1500 µg/lFluoride

50 µg/lCyanide

3000 µg/lCopper

1500 µS/cmConductivity

20 mg/lPt/Co scaleColour

50 µg/lChromium

No standardChlorine

400 mg/lChloride

Amount Allowed

StandardSubstance

150 mg/lSodium

10 µg/lSilver

10 µg/lSelenium

Dilution No of 3 at 25ºCQuantitative odour and taste

No standardQualitative odour and taste

12 mg/lPotassium

2200 µg/lPhosphorus

5.5-9.5PH

0.1 µg/lPesticides

10 ng/lBenzo3,4 pyrene (a PAH)

0.2 µg/lPAH

5 mg/lOxidisability

0.1 mg/lNitrite

50 mg/lNitrate

Amount Allowed

StandardSubstance

5000 µg/lZinc

No significant increaseTotal organic carbon (TOC)

No standardTotal hardness

1500 mg/lTotal dried solids

4 Formazin Turbidity UnitsTurbidity

100 µg/lTrihalomethanes (THMs)

30 µg/lTrichlorethene

3 µg/lTetrachloromethane

10 µg/lTetrachloroethene

25�CTemperature

200 µg/lSurfactants

250 mg/lSulphate

Amount Allowed

StandardSubstance

Prescribed Concentration or Value (PCV)

Conductivity (μS/cm)Total Dissolved Solids (TDS) (ppm or mg/l)

Resistivity (MΩ-cm)pHHardnessFouling Index (silt density)

Definition of water

Purification Technologies

Distillation

Heat water to boiling Condense water vapourCollect condensate(liquid)

In separate container

Purification Technologies

Ion – Exchange (DeI)

Chemical exchange process Works only with elementsin a charged stateOnce exhausted can be regeneratedInstantaneous demandGood food source for bacteria

Purification Technologies

Reverse Osmosis (RO)

Sophisticated filtration Physical removalRequires pressure93-98% removal of minerals99% Bacteria

Purification TechnologiesFiltration

Physical removal based on particle sizeRemoval of particles0.2µm filter size removes

bacteria (ultra – microfilters)0.1 – 0.01µm filter size

removes endotoxin (ultra-filtration)

Purification TechnologiesUltra violet irradiation (UV)

Short wavelength energy Breaks C-C bonds185nm - Small chain organic molecules254nm - Bacteria

Purification TechnologiesOrganic Adsorbtion

Concentration of organic molecules atthe surface of usually activated carbon media sometimes man made resins Low molecular weight organics185nm - Small chain organic molecules254nm - Bacteria

Particles / colloids

Endotoxins

Micro-organisms

Total Organic Carbon

pH

Silica

Heavy Metals

Hardness

Conductivity

Resistivity

UVUltra-filtrationFiltrationOrganic

AdsorbtionDeionisationReverse OsmosisDistillation

Technologies

0.030.25depends <0.25<0.03Endotoxins (Eu/ml)

1_<10/ml<100

<100/ml no P

aeruginosaor E Coli<100Bacteria (cfu/100ml)

31050Silica (ppb)

0.0050.01<0.01Aluminium (mg/l)

0.010.2<2Nitrate/nitrite (mg/l)

0.005<2Calcium (mg/l)

0.01<0.1Chlorine/Chloramines (mg/l)

0.05 - 1_Particles (µm)

5_<50<50<500TOC (ppb)

0.050.10.1Heavy Metals (ppm)

__Hardness (ppm)

_30TDS (ppm)

18.2_1 to 101 to 10Resistivity (MW/cm)

_<35<1.29Conductivity (µS-cm)

Micro ElectronicsClean SteamClinical Laboratory

USP PharmaRenal

Market sectorParameter

Quotations for Water

If there is magic on the planet, it is contained in the water.- Loren Eisley

When the well is dry, we know the worth of water.- Benjamin Franklin

Thank you for your attention

Useful Terminology• Potable water

– Water suitable for drinking

• Hardness– The scale - forming and lathering inhibiting qualities which

some water supplies possess caused by high concentrations of calcium and magnesium

• Conductivity– The process of electrical transfer through water, measured in

microsiemens/cm.

• Resistivity– The reciprocal of conductivity. Resistivity is usually corrected to

25 degrees centigrade and expressed as megohm-cm. 1megohm-cm is equivalent to 1 microsiemen/cm

• pH– A measure of the acidity or alkalinity of a solution. pH1 is very

acid pH7 is neutral and pH14 is very basic. pH is measured using a glass electrode.

• OA– Oxygen Absorbed is a measure of organic content of water.

The water is reacted with acidified potassium permanganate and the permanganate consumed is used to quantify the organics present with the result being expressed in ppm O2

• SDI– Silt Density Index, also called Fouling Index (FI), a test used to

estimate the concentration of colloids in water; derived from the rate of blockage of a 0.45 micron filter

Useful Terminology

• Bacteria– Also known as Microorganisms are some of the simplest living

cells known usually found as single cells living “alone” or in groups as chains or clumps of cells. Cell size varies from 0.5 -10 micron.

• Colloid– A stable dispersion of fine particles in water that have a typical

size less than 0.1 micron. Colloids containing iron (Fe), aluminium (Al), silica (SiO2) and organics are commonly found in water.

• Total Dissolved Solids– A measure of the total of organic and inorganic salts dissolved

in water, obtained by drying residue at 180ºC.

• PPM– parts per million is a unit equal to milligram per kilogram of

water, ppm is equivalent to mg/l in dilute solutions.

Useful Terminology

• Ion– Any non aggregated particle of less than colloidal size

possessing either a positive or a negative electric charge. Some organic molecules are so large that even as ions they are considered to be colloids.

• Cation– A positively charged ion

• Anion– A negatively charged ion

• Molecule– The smallest particle of an element or compound that is

capable of separate existence without losing the properties of the substance.

Useful Terminology