1 Environmental monitoring MEASUREMENT OF POLLUTANTS IN WATER There are 3 kinds of water: -drinking...

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Environmental monitoring

MEASUREMENT OF POLLUTANTS IN WATER

There are 3 kinds of water:-drinking water-waste water-surface water

Drinking water or potable water is water of sufficiently high quality that can be consumed or used without risk of immediate or long term harm. It is provided by water supply networks or may be found in deep wells or springs.

Waste water or sewage comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations. In the most common usage, it refers to the municipal wastewater that contains a broad spectrum of contaminants resulting from the mixing of wastewaters from different sources.

Surface water is water collecting on the ground or in a stream, river, lake, wetland, or ocean; it is related to water collecting as groundwater or atmospheric water.

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Environment Monitor Water Quality

(video clip)

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Regulations

Waste water

Law: HG 352/2005, completion of HG 188/2002 refers to 2 types of waste water:

-industrial and urban waste waters overflowed into natural receivers (lakes, rivers) (NTPA 001)

-waste waters overflowed into sewerage networks (NTPA 002)

Environmental Protection Law 137/1995 updated by

Ordonance 195/2005

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MEASUREMENT OF POLLUTANTS IN WATERWaste water quality standard NTPA 001 (several chemical indicators)

No. Quality indicator Unit Limit values Analysis method

1. pH pH units 6,5-8,5 SR ISO 10523-97

2. Suspended materials mg/dm3 35,0 (60,0) STAS 6953-81

3. Biochemical Oxygen Demand at 5 days

mg O2/dm3 25,0 SR EN 1899-2/2002

4. Chemical Oxygen Demand (CCOCr) mg O2/dm3 125,0 SR ISO 6060-96

5. Ammonia (NH4+)6) mg/dm3 2,0(3,0) SR ISO 5664:2001

SR ISO 7150-1/2001

6. Nitrates (NO3-)6) mg/dm3 25,0(37,0) SR ISO 7890-2:2000;

SR ISO 7890-3:2000

7. Sulphide (S2-) mg/dm3 0,5 SR ISO 10530-97

8. Phenols (C6H5OH) mg/dm3 0,3 SR ISO 6439:2001;SR ISO 8165/1/00

9. Oil products mg/dm3 5,0 SR 7877/1-95

10. Total phosphorus (P)6) mg/dm3 1,0(2,0) SR EN 1189-2000

11. Synthetic detergents mg/dm3 0,5 SR EN 903:2003

12. Aluminium (Al3+) mg/dm3 5,0 STAS 9411-83

13. Calcium (Ca2+) mg/dm3 300,0 STAS 3662-90SR ISO 7980-97

14. Lead (Pb2+)3) mg/dm3 0,2 STAS 8637-79;

15. Nickel (Ni2+)3) mg/dm3 0,5 SR ISO 8288:2001

16. Zinc (Zn2+)3) mg/dm3 0,5 STAS 8314-87

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MEASUREMENT OF POLLUTANTS IN WATERWaste water quality standard NTPA 002 (several chemical indicators)

No. Quality indicator Unit Limit values Analysis method

1. pH pH units 6,5-8,5 SR ISO 10523-97

2. Suspended materials mg/dm3 350,0 (60,0) STAS 6953-81

3. Biochemical Oxygen Demand at 5 days

mg O2/dm3 300,0 SR EN 1899-2/2002

4. Chemical Oxygen Demand (CCOCr) mg O2/dm3 500,0 SR ISO 6060-96

5. Ammonia (NH4+)6) mg/dm3 30,0 SR ISO 5664:2001

SR ISO 7150-1/2001

6. Cyanide total (CN) mg/dm3 1,0 SR ISO 6703/1-98-2/00

7. Sulphide (S2-) mg/dm3 1,0 SR ISO 10530-97

8. Phenols (C6H5OH) mg/dm3 30,0 SR ISO 6439:2001;SR ISO 8165/1/00

9. Oil products mg/dm3 5,0 SR 7877/1-95

10. Total phosphorus (P)6) mg/dm3 5,0 SR EN 1189-2000

11. Synthetic detergents mg/dm3 25 SR EN 903:2003

12. Cadmium (Cd-) mg/dm3 0,3 SR EN ISO 5961:2002

13. Zinc (Zn2+) mg/dm3 1,0 STAS 8314-87;SR ISO 8288:2001

14. Lead (Pb2+)3) mg/dm3 0,5 STAS 8637-79;

15. Nickel (Ni2+)3) mg/dm3 1,0 SR ISO 8288:2001

16. Manganese (Mn) mg/dm3 2,0 SR 8662/1-96

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Regulations

Drinking water

Law 311/2004, completion of Law 458/2002

ParameterLimit value(number/100 ml)

Escherichia coli (E.coli) 0

Enterococi 0

Microbiological parameters

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Drinking waterLaw 311/2004, completion of Law 458/2002

Chemical parameters

Parameter Limit value Unit

Ammonia 0,50 mg/l

Chlorine 250 mg/l

Conductivity 2.500 S cm-1 la 200C

Nitrate 50 mg/l

Nitrite 0.5 mg/l

pH > 6,5; < 9,5 unităţi de pH

Sulphate 250 mg/l

Sulphyde 100 g/l

Turbidity < 5 UNT

Chromium total 50 g/l

Zinc 5.000 g/l

Iron 200 g/l

Manganese 50 g/l

Copper 0.1 mg/l

Alpha global activity 0,1 Bq/l

Beta global activity 1 Bq/l

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Drinking water – USA National Primary D.W. regulations

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Drinking water – USA National Primary D.W. regulations

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Surface waterLaw Order 1146/10.12.2002

Chemical parametersParameter Unit Limit values

I II III IV

pH pH units 6,5 < pH < 8,5

Dissolved oxygen mg/l O2 7 6 5 4

BOD5 mg/l O2 3 5 10 25

CODCr mg/l O2 10 25 50 125

Nitrate mg N/l 1 3 6 15

Nitrite mg N/l 0.01 0.06 0.12 0.3

Total phosphorus mg/l 0.1 0.2 0.4 1

Zinc total g/l background 100 200 500

Chromium total g/l background 2 4 10

Nickel total g/l background 50 100 250

Lead total g/l background 5 10 25

Copper total g/l background 20 40 100

Anionic detergents g/l background 500 750 1000

Oil hydrocarbures g/l background 100 200 500

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How to measure all of these parameters?

There are various methods, techniques and equipments devoted to measure water quality parameters.

They are divided in:

- in-situ methods

- laboratory methods

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Water sampling

(video clip)

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Measurement of water pollutants using ion selective electrodes (ISE)

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Ion selective electrodes

(video clip)

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Ions to be measured using ISE

CationsAmmonium (NH4+) Barium (Ba2+) Calcium (Ca2+) Copper (Cu2+)

Lead (Pb2+) Mercury (Hg2+)Potassium (K+)Sodium (Na+)Silver (Ag+)

AnionsBromide (Br-)Chloride (Cl-)Cyanide (CN-), Fluoride (F-)Iodide (I-)Nitrate (NO3

-)Nitrite (NO2)Perchlorate (ClO4

-)Sulphide (S-)

Thiocyanate (SCN).

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Advantages of measuring using ISE

• very fast and easy measurements• the possibility of implementation of continuous monitoring• relatively inexpensive• wide range of concentration for a large variety of ions• by fulfilling the imposed conditions of maintenance and calibration, one

can achieve accuracy and precision levels of 2 – 3 %, sometimes comparable with analytical techniques.

• unaffected by sample colour and turbidity.

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Measurement principle of ISE (example pH measurement)

Measurement electrode

Reference electrode

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Measurement and reference electrodes

Glass bodyMeasurement

electrode

Bulb filled with potassium chloride

buffer solution

Voltage produced across thickness of

glass membrane

Very thin glass bulb chemically doped with lithium ions

Wire connection

Measurement electrode Glass body

Bulb filled with potassium chloride

buffer solution

Voltage produced across thickness of

glass membrane

Very thin glass bulb chemically doped with lithium ions

Wire connection

Reference electrode

Wire connection

Filled with potassium chloride

buffer solution

Porous junction

Glass or plastic body

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Nernst equation

anF

RTEE lg

303,20

a = activity of ions (for pH, a is the activity of hydrogen ions)

C = ion concentration

γ = activity coefficient

E = measured potential

E0 = standard electrode potential (E for a = 1)

R = gas constant

T = absolute temperature [K]

F = Faraday constant

n = ion charge (n = 1 for pH)

apH lgCa

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nF

RTslope

303,225 oC

50 oC

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KCl

shieldedcable

reference electode (Ag/AgCl)

junction glass frit

measurement electode (Ag/AgCl)

membrane

referencefilling hole

reference junction

filling hole

Combined (double junction) electrode

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Measurement of water pollutants using ion selective field effect transistors (ISFET)

Principle of operation of an ISFET

Source

Substrate

InsulatorSensitive layerDrain

Gate

p-type Si

VGS

G

D

S ID

VDS

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Measurement of water pollutants using ion selective field effect transistors (ISFET)

Some ISFET Characteristics

Analyte Sensing structure Comments

Ammonium

PVC treated with HMDS for adhesion

Sensitivity: 30mV/part NH4

Detection limit: 2x10-6

Both sensor and reference fabricated FET

Cd2+, Pb2+ Polysiloxane + cyclodextrin Sensitivity: 29 mV/decade for Cd2+

Sensitivity: 15 mV/decade for Pb2+

Lifetime: 3 months

Cu2+ Etched chalcogenide glass with aluminium adhesion layer

Sensitivity: 28 mV/part CuResponse time: 5 sLifetime: several weeks

Cyanide PVP (poly-(4-vinylpyridine-co-styrene) with horseradish peroxidase as sensitive layer

Sensitivity: 10-7 to 10-5 molar solutionReproducibility: 20 % (pH dependent)

K+ Polysiloxane with poly-HEMA adhesion layer as sensitive layer

Sensitivity: 59 mV/decadeLifetime: 75 days

Na+ Polysiloxane Sensitivity: 56.7 mV/decade

pH Tin oxide Sensitivity: 58 mV/pHLinear between pH 2 to 10Response time: 1 s

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MEASUREMENT OF POLLUTANTS IN WATEROptical methods

They are based on:

-reflection

-colorimetry

-absorbtion of light

-fluorescence

E = hc/λ = hν

Fluorescence

This method utilizes the fluorescence, either natural or induced, of a compound. Fluorescent chemicals absorb radiation of a specific wavelength and emit at another.

Monochrome light

ν0 ν1

Light detector

Sample

Planck equation

h = Planck’s constant (6.626 ·10-34 J·s)

C = velocity of light in vacuum

λ = wave length

ν = light frequency

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Nephelometry

White light or infrared light

White light or infrared light

Light detectors

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Colorimetry

A = log(I/Io) = knC

Visual tests

Monochrome light

I0 I

Light detector

Sample

Photometer

Beer’s law

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Colorimetry

Water Quality Colorimeter

(video clip)

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Measurement of water parameters using UV-VIS spectrophotometer method

The measurements may be performed in laboratory or in the field

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Spectrophotometer DR 2800

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Spectrophotometer DR 5000

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Cuvette tests method

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Parameters to be measured

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Hach robot for spectrophotometric measurements

(video clip)

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MEASUREMENT OF POLLUTANTS IN WATERMeasurement of metals using Atomic Absorption Spectrophotometry (AAS)

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Measurement of metals using Atomic Absorption Spectrophotometry

Beer – Lambert’s law

lcl

I

IT 1010

0

T = transmission (transmissivity)

α = absorbtion coefficient

l = pass length (distance the light travels through the material

ε = molar absorptivity of the absorber

c = concentration of the absorber in the material

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Difference between atomic and molecular spectroscopy

Atomic spectroscopy Molecular spectroscopy

- concerns only the properties of atoms - concerns the molecules, which are infinitely more numerous

- concerns all the interaction of electromagnetic waves

- we can found the nature and the amounts of a given element in the sample

- gives us more advice than atomic spectroscopy especially about chemical functions and structure of matter

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Analytik Jena Zeenit A700 AAS spectrophotometer

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AAS Block Diagram

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Flames used in AAS

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Light source

Hollow cathode lamp

Xenon lamp

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Detection limits for some elements (μg/l)

Element Flame Electrothermal (furnace)

Ag 3 0.02

Al 30 0.2

Ca 1 0.5

Cd 1 0.02

Cr 4 0.06

Cu 2 0.1

Fe 6 0.5

Mn 2 0.02

Ni 3 1

Pb 5 0.2

Sn 15 10

Zn 1 0.04

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Dissolved Oxygen (DO) Measurement

There are three methods:•Azide-Winkler method•Metering with DO probe•Field kits

Dissolved oxygen analysis can be used to determine: • the health or cleanliness of a lake or stream, • the amount and type of biomass a freshwater system can support, • the amount of decomposition occurring in the lake or stream.

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Dissolved Oxygen (DO) Measurement (Winkler method)

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Dissolved Oxygen (DO) Measurement with Clark electrodes

Clark type electrode

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Dissolved Oxygen (DO) Measurement

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Influence of the temperature upon Dissolved Oxygen

curve A – fresh water

curve B – salted water

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Biochemical Oxygen Demand (BOD)

• BOD is a measure of the oxygen used by microorganisms to decompose the organic waste dissolved in water.

• BOD is affected by temperature.• BOD is influenced by the content of nitrates and

phosphates dissolved in the water.• BOD is an indicator of the organic quality of water.• It is most commonly expressed in milligrams of oxygen

consumed per litre of sample during 5 days of incubation at 20 C.

Two methods of measurement:- Dilution method- Manometric method

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BOD Level(in ppm)

Water Quality

1 - 2Very GoodThere will not be much organic waste present in the water supply.

3 - 5 Fair: Moderately Clean

6 - 9

Poor: Somewhat PollutedUsually indicates organic matter is present and bacteria are decomposing this waste.

100 or greater

Very Poor: Very PollutedContains organic waste.

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Dilution method

BOD can be calculated by:

Undiluted: Initial DO - Final DO = BOD

Diluted: (Initial DO Final DO) x Dilution Factor

A very small amount of micro-organism seed is added to each sample being tested

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Manometric method

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MEASUREMENT OF POLLUTANTS IN WATERBiochemical Oxygen Demand (BOD)

Working procedure

Required apparatus:BOD bottlesSpatula scoopBOD incubatorSeal cup, stir bar

Reagents2 potassium hydroxide pellets

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MEASUREMENT OF POLLUTANTS IN WATERBiochemical Oxygen Demand (BOD)

Working procedure

1 Environmental monitoring MEASUREMENT OF POLLUTANTS IN WATER There are 3 kinds of water: -drinking...

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