water analysis.pdf

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Water Analysis

1)Introduction- water for drinking, recreation & others

2) Water quality and standards

3)Analytical Methodologies: Field and laborator

measurement,Pretreatment and Chemical Analysis

4)Special Methods: Automated Analysis, Flow Injectio

Analysis (FIA), and Ion Chromatography (IC)

1) INTRODUCTION

Standard or Reference Values set up by governmen

bodies e.g. EPD, Water Works Department, etc

Analytical methods two types (laboratory and field

methods) REFERENCE:Standard Methods for the

Examination of Water & Waste Water (628.161

S78) jointly issue by

i) American Public Health association

ii) American Water Works Association

iii) Water Environment Federation

Different methods used by different water bodies :

i) Clean water - drinking water, fresh water

ii)Water for recreation-seawater, beach & river water

iii) Dirty water - waste water, water pollution, etc.iv) Processes water - water for industrial use,

consideration for cost, corrosion & fit for purpose.

Some can be very clean such as DI water.

v) Water for specific uses - agriculture/irrigation,

cement/concrete mixing, cooling water, etc.Wastewater, Water, Soil & Sediments Analysis

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2) WATER QUALITY AND STANDARDSStandards

re normally set up by government agents or international

bodies & variable with different water bodies

.1)Drinking water : i) Microbial aspects, ii) Chemical

spects, iii) Radiological aspects, iv) Acceptable aspects

WHO Guideline values

Historically, spread of water borne disease is due to

ontamination of potable water by dirty water (sewage)

with faecal bacteria e.g. London before building deep

underground sewers & surface drainage water debate in

Bombay, India before link of illness to bacteria hasstablishedDevelopment of water supply system for citie

nd associated regulations, practices and control

-1914:U.S. Public Health Service set the standards

for water for bacteria.

-1925 : Cu, Pb & Zn, Pb = 0.1 mg/L (City watersupply by leaded pipeline)

-1946: 7 additional chemical substances

-1962: Pb 0.05 mg/L (availability of method) Current

WHO guideline forPb : 0.01 mg/L

-other chemicals added to water: i) chlorination fordisinfecting water to avoid water borne hyphoid & other

enteric diseases, ii) fluoridation: start in 1945 to reduce

dental cavities. Not too high or too low for best effect.

-Drinking water is metered & used to calculate waste wate

charges in HK.World-wide shortage of water.In Californiaincrease 3x cost to achieve effective water-saving.

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World health Organiszation (WHO): Guidelines for

rinking water quality, Third Edition, 2004.

WHO issues guidelines for quality and standards of

rinking water, risk assessment, monitoring & analysis

methods, sources of pollution, water treatmentDepending on sources of water, water quality varies

reatly in different places, some salty water or hard

water have to be used in drinking. The most important

fit for drinking with no known health hazards

Following parameters specified in WHO guidelines:

Bacteriological quality: Faecal bacteria indicator (E

oli) as general standard (individual bacteria if needed)

) Chemicals of health significance (Guidelines)

a)Inorganic constituents - heavy metals & anions

b)Organic constituents-chlorinated hydrocarbon,

PAH, Nitro-compounds, BTEX (benzene, toluene

ethylbenzene and xylene)

c) Pesticides

d) Disinfectants and disinfectant by-productsi) Radionuclides for alpha and beta emitters

v) Substances that may give rise to complaints- other

metals, hardness, pH, turbidity, dissolved solid, etc.

) Early edition focus on guidelines & standards. From

rd edition (2004), focus is changed to pollution sourceontrol & prevention measures (www.WHO.int)

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Standard based on E.Coli as indicator organismproblem

f mixing up portable water with sewer [connect to the

wrong pipe]

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System survey guidelines for water classification]

Guideline for verification of microbial quality]

Guideline for Bacteriological Quality:

Analytical question : Zero detection limit ??


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G

uidelinesforhe

althsignificant

chemicals(86listedwithguidel

inevalues)

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http://localhost/var/www/apps/conversion/tmp/scratch_3/Table_WA.ppt


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Guidelines for Radionuclides

-Determination of individual radioactive species requiressophisticated and expensive analysis and their concentrations

are normally very low in water, a screening procedure fortotal

radioactivity present in the form ofalpha and beta radiation

s thus used. The screening levels for drinking water below

which no further action is required are 0.5 Bq/litre for gross

alpha activity and 1 Bq/litre for gross beta activity. [Note : SIunit for radioactivity is Becquerel (Bq), where 1 Bq=1

disintegration per sec.]- To facilitate quick response, HKObservatory hosts the

monitoring network operated by chemists from Government La

- Monitoring air, water and dairy products to check against

potential leakage from nearby Daya Bay nuclear power station

- High background in HKdue to HKgranite (igneous rock)

[HK ~3mCi (100MBq)


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Sv

he sievert (Sv) is the SI unit of equivalent or actual radiation

ose received by receptor (Note: Bq/Ci is energy emitted from

adiation source). Radiation measured in Sv are designed to

present the biological effects of ionization radiation. However,

fferential absorption exhibits by different biological tissue.aking differential absorption into consideration, the unmodified

bsorbed dosage of radiation energy is known as grays (Gy). For

ological impact, further calculations must be performed to

onvert absorbed dose into effective dose, the details of which

epend on biological context, far more complicated than just

multiplying by a weighting factor.From previous

exposure study,

Man-made

radiation


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Guidelines for Aesthetic Qualitynstituent/Characteristics Unit Guideline values Remarks

umintum mg/L 0.2

hloride mg/L 250

hlorobenzenes & chlorophenols - no guldeline value set these compounds may affect taste & odou

olour true colour units (TCU) 15

opper mg/L 1.0

etergents - no guldeline value set no foaming or taste & odour problems

ardness mg/L (as CaCO3) 500

ydrogen sulfide - not detectable to consumers

on mg/L 0.3

anganese mg/L 0.1

xygen-dissolved - no guldeline value set

H - 6.5 - 8.5

odium mg/L 200

olids--tolal dissolved mg/L 1000

ulfate mg/L 400

aste and odour inoffensive to most consumers

emperature-

no guldeline value seturbidity nephelometric turbidity units (NTU 5 preferably


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2.2) Water for recreation (beach & swimming pool)

less stringent as compared to drinking water

Under Water Pollution Control Ordinance, HKis divided

nto 10 water control zones. Water quality varies

depending on different water control zone, with the most

tringent in Tolo Harbour & Channel. The reason is due

o the special regional geography with small mouth for

holding a large volume of water.In HK, 36 gazetted bathing beaches, 11 on HKIsland &

25 in NT & outlying islands.

Beaches are classified by E.Coli count /100 mL as Good610). HKEPD issues regular announcement on beach

waterquality during bathing season. Major water pollution

s due to excess sewage discharged with little treatment.

- Majorproblem

areas :

Typhoon

shelter,

KowloonBay near

Kaitak :

stagnant

water with

littlecirculation

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2.3) Dirty Water

Polluted water- Three types : i) Sewage water (toilet &

itchen), ii) Drainage water (rainwater) & iii) Industrial

ffluent waters

Standards set by HKEPD are different for different water

ones. Allow mixing of sewage & industrial water in old

ndustrial areas. Mix of drainage & sewage water not allow.

Control water zones with different standards for discharge

f wastewater. Most strict at Tolo harbour

parameters includes BOD, COD, grease & oil, metals, etc.

nformation available from HKEPD website

In Holland, COD & BOD are used to charge wastewater.

.4) Processes water: ingredients in finished products,

uoyant transporting

media,coolant,steam

power generation

variable quality by

ifferent industries)

.5) Water for

pecific uses : water

or irrigation, mixingement /concrete &

or cooling water in

ir conditioning

water quality

egulated & regularlymonitored )

T a b le 3 R e c o m m e n d e d v a l u e s f o r w a t e r u s ein m ix i n g c o n c r e t e

S u b s t a n c e Threshold valuefree CO2 25 mg/L

pH approx. 7

sulfide not detectable

sulfate 250 mg/L

chloride 1 500 mg/L

ammonium 100 mg/Lmagnesium 200 mg/L

potassium permanganate 25 mg/L

consumption

humic acids, hydrocarbons not detectable

F o r c o n c r e t e re i n f o r c e d w i t h ir o nchloride 100 mg/Lnitrate 20-50 mg/L

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(3) ANALYTICAL METHODOLOGY

3.1) Field Sampling And Measurement

3.1.1) Sampling and preservation

3.1.2) Direct measurement in field

3.2) Measurement in Laboratory3.2.1) Water quality testing methods

I) Microbiological testing methods

II) Radiological testing methods

III) Chemical testing methods

A) Sample pretreatmentB) Chemical analysis

a) General properties analysis

b) Specific chemical analysis

3.2.2) Automatic Analysis Methods

3.1) Field Sampling and Measurement

3.1.1) Sampling and Preservation

- Surface water : Collection by bucket or sample

container dipped into water in front of vessel

- Drinking water : Running time of 15 to 30 min prioto collection. Sterile glass bottle for bacteria testing

- Waste water: Similar to surface water collection. Fo

QC purpose, use 2-hrs pooled or daily pools samples

-Processes water: Use processes water to wash bottle

- Ground water: Tube wells or shafts with pumps orbuckets

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Table 1 Conservation of substance present in water

Parameter Preservation Method Maximum storage timetrace metals 5 mL HNO3/L several weeks

ammonium, total N2 5 mL HNO3/L few days

mercury 1 mL 10% K2Cr207-

solution/L few days

nitrite no stabilization possible, cooling to 4oC 1 day

cyanides alkali to pH = 11 1 day

iron-II addition of 2,2-bipyridine 1 day

sulfide 2 mL 10% zinc acetate solution/L 1 week

phenols alkali to pH = 12 1 week

Fig.1 Schematic

representation of a

tube well

ampleConservation

Different methods

or different analytes

No HNO3forCOD

No chemical addedorBOD

Sample preservation

an affect analysis

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Domestic Waste Water Sampling

Waste water

from sewer

Screening &

Degritting Remove

solids >

6mm

Primary

SedimentationRemove 50%

suspended

solid as

Primary

Sludge

SecondaryBiological

Treatment (6-8 hrs)

Reduce

ammonia-N and

total nitrogen by

microbes in

activated sludge

Effluent

Discharged

Excess activated

sludge digested,

de-water & landfill Activated Sludge Recycled

Water

Samples

Aeration with

activated sludge

Sedimentation

Tank

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.1.2) DIRECT FIELDMEASUREMENT

- Simple operation and procedure, give immediat

results with no problems associated with sample

storage and transportation

- Specific equipment for each measurement, e.g.glass electrode forpH, Fluoride ISE forF-,

oxygen electrode for dissolved oxygen,

conductivity meter for conductivity measurement

- For spectrophometric measurement, coloured

glass comparators are used for quantitatione.g. use of o-toluidine-HCl for residual chlorine.

Recent development using optical fibre with

computer-attached monochromator

- Parameters includes temperature, weather

conditions, Redox potential, Dissolved oxygen,Active chlorine, conductivity, pH, etc.

- Meter-type instruments with no power

requirement or run by battery power

pHmete

Colorimeter

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Coloured glass

as standard


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3.2) Measurement in Laboratory

3.2.1) Water quality testing methods

I)Microbiological Testing Methods

-Expensive to detect specific pathogen. Thus, use of

indicator organisms are used. Requirements :i) They are always present in contaminated water,

absent when faecal contamination not present,

ii) generally survive longer than pathogens, and

iii) easy to identify.

-If indicator organism absent, water is assumed safe.Total coliform group : defined as all of the aerobic &

anaerobic, Gram-negative, non-spore-form rod-shaped

bacteria which ferment lactose with gas formation

within 48 hours at 35oC given by Standard Methods

for the Examination of Water & Wastewater.Faecal or thermal tolerant coliform (E.coli): the

ncubation temperature is 44.5 0.2C and other

conditions kept constant coliform from human

For individual pathogenic bacteria : tradition

method by colony counts in selective media, or newPCR/DNA techniques for detecting specific bacteria

Method : Pass 100-mL sample through sterile

membrane filtration following by incubation inlactose-peptone solution at 35oC and counting

confirmed colonies (by morphology, colour and

biochemical identification) after 24-48 hours.

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) Radiological Testing Methods Alpha particle: 1)Positivcharged particles,

2) shortest pentration

distance

eta

article: 1)

egatively

hargedarticles

) Longer

enetration

istance

Gamma Ray:1) Lo

abundance

radiation, 2) longe

penetration distancUnstable nucleus decays by emitting

pha particle, beta particle and

amma ray (high energy radiation

g. X-ray)

A) Measurement in field :

Measure beta-particle or gamma radiation due to long distancemeasurement. Alpha particle is too short a distance to measure.

It depends on the penetration power of radiation through given

hickness of Aluminum block to distinguish 241Pu, 129I or 90Sr.

Thus, one can put detector behind a given thickness of Al block

o identify type of radiation. (Qualitative)

The intensity measurement is more a problem for quantitativenalysis, as sources & their distance to the detector are needed.

/ x

neutron

Paper

Thin metal foil Thick Pb block

Heav

water

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I) Scintillation counter measures

onizing radiations. The sensor

onsists of a transparent phosphor,

lastic usually containing

nthracene that fluoresces when

truck by ionizing radiations. A

ensitive PMT measures the light

rom the crystal for counting and

ossibly quantify the amplitude of

he signals from phospor (Moreensitive than GM,semi-quantitive)

I)Geiger Mller (GM) count

Cheap, portable, detect ionizin

radiation, e.g. beta particle &

gamma ray. Special model det

alpha particle. However, low

sensitivity. An inert gas-filled tube (He, Ne orAr with halogen added) briefly conducts electri

city when a particle or high energy radiation

makes the gas conductive. The tube amplifies

this conduction by a cascade effect with outputs

displayed by a needle or lamp and/or audible

sound.(Personal monitor, Yes/No indication)

B) Measurement in the La

I) Liquid scintillation

counting is a standard

laboratory method for

measuring raditaion from

beta-emitting nuclides.(Fixed

demension Quantitative)

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http://en.wikipedia.org/wiki/File:LS6500.jpghttp://en.wikipedia.org/wiki/File:LS6500.jpghttp://en.wikipedia.org/wiki/File:LS6500.jpghttp://en.wikipedia.org/wiki/File:AustralRadMini_Applications.JPG


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mples are dissolved or suspended in a "cocktail/mixed solution

ntaining an aromatic solvent & small amounts of other fluorescen

ditives (fluors) Beta particles emitted from sample transfer energy

the solvent molecules, which transfer their energy to the fluors. T

cited molecules dissipate energy by emitting light for measuremen

ab procedures : Two common methods for gross alpha & gross

eta activities: 1)Evaporation of known sample volume to drynes

measure activity of residue (as alpha absorbs by solid material,

ot for samples with high total dissolved solid (TDS). 2)adioactive co-precipitation(precipitation on a carrier

recipitateor collector for trace metals. Using a large amount of

nsoluble K salt to co-precipitate radioactive cations):simple,

pecific, but time consuming. Lots of foreign materials added to

ample, producing contamination problem. Applicable to high TDS

amples due to saturated effect. Hard to get 100% recovery.

I) Sealed Xenon Proportional CounterArgon gas-flow proportional counterfor

ccurate determination of & radiation.

quench gas added to prevent proportional

ounter acting as a GM counter.

onization excites inert gas. When coming down to ground state,

mit light which is amplified by cascade electrodes like PMT fo

ulse mode of measurement. 2207/WA/2013/


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2207/WA/2013/II) CHEMICAL TESTING METHODS

) SAMPLE PRETREATMENT (waste & clean water)

urpose of sample pretreatment :a) cleanup major sampl

matrix, b) to remove interference & c) to enhance sensitivity

preconcentration) before GC separation & quantitation

ypes of Pretreatment Methods : i) Preconcentration

vaporation (heat lamp or hot plate): simple, inexpensive,

se for most substances, compatible to most methods, no

hemical added & no contamination. However, time

onsuming, not for volatile compounds, adsorpt-ion loss,

on-specific, high solid content, only for highly solubleompounds. Maximum ~50x .on exchange (cation, anion, chelating): simple, rapid,

nexpen-sive setup,regenerated column, very high pre-

oncentration factor. However, suitable detector, specific

xchanger & solvent needed) Isolation & Phase Separation

recipitation (inorganic & organic reagents):simple,

nexpen-sive & quite specific. However, for low soluble

ompounds with large crystals,lots of foreign ions added &

e-dissolution required.ii) Extracting Trace Pollutants from Liquid Phase

Extract trace levels of pollutants from complicated

matrixes, remove interferences and concentrate analytes

rior to chemical analysis.Commonly used for waste water

Instrument are often used to speed up the extraction andor automation of procedure


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Three major types of extraction from liquid phase : Purge &

Trap, Solid Phase Extraction & Solvent Extraction

) Purge & Trap for Volatile (Purgeable) Organic

ompounds : Two steps, 1st step is to purge organic compounds

ut from aqueous solution by gas and this leads to pre-

oncentration and removal of interferents. Second step is to striprganic compounds out from the adsorbents by carbon

isulphide or by thermal desorption.

Two types : Off-line and on-line Purge & Trap

ff-line Purge & Trap- Removal of moisture by Nafion drier t

duce the effect of water on activated carbon (polymermembrane allowed water to go through but not organic

ompounds, dried by desiccants packed in Drier)

n-line Purge & Trap with cryogenic on-column focusing

apillary column in liquid N2 to trap VOCs) with direct couplin

GC: used to handle a lot of samples at low concentration.

Purge Gas

Activated Carbon

Adsorbent Trap

Aqueous

solution

sample

Nafion

Drier

A hygroscopic ionexchange membran

fabricated in tubula

form and made up

of a co-polymer of

tetra-fluoroethyleneand fluorosulfonyl

monomer

Du Pont Nafion

F2C=C OCC OCCSO3H

nF CF3 F F

F F F F F

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Solid Phase Extraction

using cartridge

Vacuummanifold for

solid phase

extraction of

multiple

cartridges

Pressure

Procedures in SPE

) Solid Phase Extraction(SPE)

Technique involves the use of a solid sorbent selectively

dsorbing the analyte from a large volume of diluted sample

olution, and then eluting by a small volume of strong solvent

Ion Exchange Resin for pre-concentration of trace metals fromqueous low-ionic strength solution, then by hydroxide stripping

-C18SPE (Sorbent)

to preconcentrate

trace non-polar

organic compounds

from aqueousmedium

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) Solvent Extraction

Organic solvent extractionSeparating funnelmore efficient using discrete multiple

xtraction with several small volumes of extractants

Extracting Trace organic pollutants

like-dissolve-like concept for organic compounds with

rinciple based on favourable distribution ratio in the organic

hase. K = Corg /Caq.More complete extraction by multiple extractions using several

ots of smaller volumes than a large solvent volume

Choice of solvent: purity, cost, safety (toxicity & fire hazards)

nd solubility of analyte such as hydrocarbon (hexane) &

hlorinated hydrocarbon solvents (1,1,1-trichloroethylene)Best is CFC on safety & chemical grounds (high purity with

nly C-F bonds & good solubility of organics)

Problem of long extraction timea few hours and CFC isnot

nvironmental friendly

Extraction and Preconcentration of Trace Metals

Chelation of metals by EDTA and other complexes beforeolvent extraction by MIBK(methyl isobutyl ketone) forAAS

rICP determinationremoval of interference by other ionic

ompounds, e.g. phosphate

Substantial number of metals can be extracted by chloride

omplexes in HCl, e.g. Fe (III), Sb(V), Ga(III), Ti(III),

Au(III),Mo(VI), As(III) & Ge(IV)

pH is important for extraction & should be optimized

Chelating resin (Chelex 100) [styrene-divinyl copolymer with

aired iminodiacetate ions as chelating groups to complex with

ansitional metals] to preconcentrate transition metals from high

nic solution and removal of interferents2207/WA/2013/23


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)CHEMICAL ANALYSIS

- Two main types : general and specific analysis

a) General properties of water

i)General observations:colour, odour & appearanc

ii) pH or alkalinity/ acidity (acidic/base capacity)iii) Dissolved and undissolved substances

Total residue dried at 103-105o C (as mg/L):

both dissolved and undissolved solid content

Total suspended matter(as mg/L): undissolved

solid only

Turbidity : cloudiness of solution, related to

suspended solid content except for smaller particles

NTU turbidimeter

is used for measuringnephelometric turbidity

units (NTU) based on

scattered light

measurement with

calibration by a primarystandard for turbidity (an

aqueous suspension of

formazin, an insoluble

polymer formed by

condensation of hydrazine

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ulfate and hexamethylenetetramine)


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Conductivity (as mS): electrical

onductivity is a total parameter for

dissolved and dissociated ionic

ompounds. In seawater, it is related

o salinity. It can be used to calculate

he total ion content in given samples

Dissolved oxygen -important

ndicators for water quality

COD (chemical oxygen demand) &OD (biochemical oxygen demand).

BOD starts as an empirical parameter

o assess water pollution by measuring

he quantity of dissolved oxygen to

xidize organic compounds found in

water with assistance of microorgan-

ms & under defined experimental

onditions. It varies with conditions

uch as temperature, dissolved O2, levels or type of bacteri

& less reproducible compared to COD. However, a lot of

istorical data using BOD for polluted waters, making it an

ssential parameter (To set charges for waste water in EU)

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Grease & Oils: indicate total organic content, measure byissolving organic matters in CFC (now hexane afterCFC

an), evaporate to dryness and weigh

Hydrocarbons: direct FTIRon

olvent extract for total hydrocarbons.

) Specific Chemical Analysis: i) Organic matters includ

Grease & Oil, Hydrocarbons, BOD & COD, Trace organics


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OD - Uptake of oxygen during 5 days or longer by biological

educing system such as activated sludge system. In UK, 5 days

dopted during London sewer construction based on average tim

or water to go through river Thames. ForEU, 7 days is adopted

o meet weekly work schedule.Dissolved Oxygen (DO) measure

y electrode with amperometric detection before and after 5 or 7ays incubation at 20/27oC with or without the seeding of bacter

BOD Empirical parameter covering organic compound

educed substances of nitrogen, sulphur, phosphorus & som

metallic species. (Dl-D2)-(Bl-B2)x f

Pwhere D1 & D2 are DO (mg/L) of diluted sample immediatel

fter preparation and after 5 or 7 days of incubation at 20/27o

espectively; B1 & B2 are DO seed control before and afte

ncubation respectively; P is dilution factor and f is the ratio o

eed in diluted sample in seed control. If no seed is added, th

actor [(B1-B2)xf ] will be zero. Several BOD bottles are used

dilutions + seed) with water filled up to top with no air gap left

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BNC Connector

Anode (silver wire)

Ag/AgCl or Calomel

KCl Electrolyte

Solution

Teflon membrane

ABS Body

oble Metal Cathode

old or Platinum)

Inner glass tubing

BOD(mg O2

/L) =

Oxygen

Electrode

BOD bottleO2 O2 O2


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COD- a few hours measurement

-a wet chemical analytical technique

-refluxing acid-dichromate with a catalyst to carryout chemical oxidation (catalyst: Ag2 (SO4))

-back-titration with ferrous ammonium sulfate

method

COD : oxidation of reduced inorganic species +

carbonaceous matter-oxidise non-carbonaceous compounds such as reduced

states of N & S, some halides, many metals & bound

hydrogen inorganic compounds

-variable oxidation efficiency e.g. pyridine 0.8%

benzene 8%, toluene 22.5%, o-cresol, valine, sodiumstearate >90%

Chemical oxygen demand (COD) is defined as the

amount of oxygen in the form of oxidizing

agent consumed in the oxidation of organic water

components. The degree of oxidation depends upon the

type of substance, pH value, temperature, reaction timeand concentration of oxidizing agent as well as the type

of added accelerators, if any.

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Trace Organics

-Often in complicated matrix require cleanup

-Analytical methods: IR, MS, GC, GC-MS, Florescence

(PAH) and electrochemical techniques- Organic pollutants e.g. phenols, surfactants, etc


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Trace metallic elementsi) AAS : flame & graphite

urnace, ii) ICP-AES (ppm) and ICP-MS (ppb),

i) Electrochemical stripping techniques, useful for tracemetal analysis in seawater.

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Anions (Cl- and SO4=) are monitored in cooling water as

ndicator for corrosion

Active chlorine compounds

residual chlorine determine by amperometric titration

sing standard ferrous sulphate or by colorimetric methods

sing o-toluidine-HCl and coloured glass comparator.

Nutrients in water (PO4=and NO3

-).

Both are limiting nutrients in soiul for algae and plants.

Used as fertilizers to enhance plant growth. Can causeutrophication (excessive algae growth known as algae bloom

present in water at high levels under favourable conditions.

) Inorganic compounds

Hardness of water : total dissolved divalent cations as

measured by EDTA titration.

Anions:requiredppm/ppb determination in acid rain analys

high tech industries. 2 methods i)Ion Selective Electrode

ISE, ii) Suppressed Ion Chromatography Ion Exchange

olumn to separate anions using NaOH as eluent.Suppressoolumn to reduce background conductivity via removing H+

ith OH-to form H2O before conductivity detector

i) Non-suppressed Ion Chromatography (Non-suppressed IC)

Same as (ii) except no suppressed column, Use weak

rganic acid as eluent which absorb UV for indirect UVetection to avoid patent on suppressor (expired now)


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Fig. 2.Fraction of

ammonia and

ammonium ions

a function of pH.

ForNH3-N, Nessler titration

r electrode (ISE) method

Fig. 1, a glass electrodeounted inside a gas-

ermeable membrane toeasure pH) is used. It

easures only NH3.

he ratio between NH3

NH4+ depends on

olution pH (Fig. 2).

It operates at 0-50o

C,orking range:0.01-17000

pm (1.0 to 5x10-7M).

Only operate in aqueous

olution & interfere by oil

grease covering up the

as-permeable membrane.For sample ionic strength

1.0M re uires ad ustment

Fig. 1.

Construction ofammonia electro

Nitrogen Content in Wastewater

otal Nitrogen = Ammonia-nitrogen (NH3-N)+Organic-nitrogen

Org-N)+Nitrate-nitrogen (NO3-N)+ Nitrite-nitrogen (NO2-N)

itrogen is essential for formation of proteins in cell growth and thus

eded to keep activated sludge.However,too much causes algae boom

mmonia is toxic to fish, and nitrates at high enough dosages in the

inking water cause methemoglobinemia in infants as it can convert to

trites in the stomach and interfere with the oxygen-carrying capacity

hemoglobin in blood.Nitrogen exists in NH3,

rganic-N, nitrate & nitrite

wastewater. Under right

onditions, each canonvertible to the others.

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Total Kjeldahl Nitrogen (TKN) is obtained by digesting sample

or two and a half hours in H2SO4and collecting NH3 distilled

or analysis. Result consists of (organic + inorganic) nitrogen plu

H3-N. Thus, organic nitrogen can be calculated by

ubtracting NH3-N and inorganic nitrogen from TKN in the sam

ample.

In field, pH should keep to < 2 by H2SO4 and temp. at 4oC

mmediately after sampling to reduce degradation.

In laboratory, pH adjusted to 9.5 using a borate buffer and

olution distilled into a receiving solution of either boric acid for

Nessler titration or into H2

SO4

for ammonia ISE determination.

Nessler reagent (0.09 mol/L solution ofK2[HgI4] in 2.5 mol/L

KOH) is used to detect small amounts of ammonia. A yellow

oloration indicates the presence of ammonia and at higher

oncentrations, a brown precipitate may form. The sensitivity is

bout 0.3 gNH3in 2 L.

NH4+ + 2[HgI4]

2 + 4OH HgOHg(NH2)I + 7I + 3H2O

O3- & NO2

-Analysis (Inorganic nitrogen, ISE + Cd)

Typically, < 1 % N in form of nitrates (NO3-) or nitrites (NO2

-)

he ratio reflects microbial balance

NO3-

converted to NO2-

by a Cd reduction column or usingydrazine sulfate for the determination ofNO2

-(Total nitrate afte

trate reduction).NO2

- is determined by diazotizing with sulfanilamide and

oupling with N-(1-naphthyl)-ethylenediamine dihydrochloride t

orm a highly colored azo dye which is measured colorimetrically

NO3-= total NO2-(after nitrate reduction)-NO2- (without nitrateduction).

2207/WA/2013/


31/40

Injection of phosphatestandards (~100 ug/mL)

and samples

he intermediate product (NH4)3PO4-12MoO3 is a yellow colore

o(VI) complex. When it is treated with ascorbic acid, the bluelored Mo(V) complex formed is detected spectrophotometrical

Phosphorus compound analysis include Total phosphorus,

-phosphate, hydrolyzable phosphate (total inorganic phosphate

& organically bound phosphate in water, wastewater or soil.

Natural total phosphate in water < 0.1 mg/L, normally fixed i

oil and non-toxic. Requires. frequent monitoring in wate

nalysis, leading to use of FIA for automatic determination.

2207/WA/2013/


32/40

4) SPECIAL METHODS: A) Automation in Water

Analysis. 4.1)A lot of samples for analysis automatio

different degrees). Normally first for time consuming ste

n sample preparation such as dilution orpHadjustment.

.2) 3 essential elements in automation : brain (decision

making by computer), eye (sensor) & hand (actuator).

.3) The most simple system is automated titration with

ndicator electrode (eye), generator electrode or autopipet

hand), and microprocessor/computer /electronic circuitry

brain) for end-point detection.

2207/WA/2013/

Generator electrodes

-Pt coil- Coulometrically

generate Br2from Br-

) Discrete Automatic titration - electrochemicaltitrant generation and detection

ndicator electrodes

Two Pt flags

Amperometrically

etect

r2/Br-ratio at bothelectrodes


33/40

Operation : i) Conditioning of electrolyte by generating a fixed

amount ofBr2 (indicated by constant current i) ii) Add sample

o reduce current, iii) Generate Br2till current reaches constant

current i again, iv) measure coulomb passed and calculate the

amount ofBr2 generated assuming 100% coulombic efficiency.

Ascorbic acid is back titrated with Br2 generatedby

lectrolysis at anode reaction

Iodine is added as its redox reaction (I-/I ) with ascorbic acid

s more reversible & it can be regenerated by reaction with Br2.

Titration of Ascorbic Acid With Bromine Generated

Ascorbic acid + Br2 2Br- + 2H+ 2207/WA/2013/33

a single-channel TechniconAutoAnalyzer system

Proportional Pump & Manifold

I) Continuous Flow SegmentedAutoanalyser: Commercialutoanalyser incorporating sample preparation & analysis

vailable forCOD, trace metals & nutrients (nitrate, nitrite,

mmonia andphosphorus)

First autoanalyser for water analysis with segmented

ow and air bubbles separating different samples

Dialyzerampler

Note:Bubbles causes disturbance

in detector baseline.Devices added

to remove bubbles before detector


34/40

a) Representation of a simple flow

injection analyser; b) Sample flow

in tube containing a plug of

sample; c) typical response over

time for samples and standards

II) Continuous Flow Non-segmented Analyser

Analyser based on newly deveoped Flow Injection Analysis (FIA

o air bubble to isolate samples. Use only segments of carrier liqui

separate samples.Require accurate control in flowrate & volume

ample injection to achieve repeatable dispersion during each run fo

harp peaks at detector. FIA resemble HPLC with an empty colum

2207/WA/2013/3

Note:

Asymmetri

peak with

tailing

Successful development ofHPLC makes suitable valves and low

ressure pump commercially available at affordable price, leading t

e development ofFIA for non-segmented flow auto-analyzer. Du

its flexible design using parts from HPLC, FIA is now largely

placed the dedicated Continuous Flow Segmented Analyzer inutomation for water analysis. The simplest FIA system is using Ion

elective Electrode for continuous flowdirect analyte detection.FIA

ystem with the widest applicationis using UV-Visible detector.

Simple Ion Selective Electrode combination electrode with built-in

ference electrode for monitoring specific ion. As no separation

efore detection, the detector system (Fluoride ISE) must be very

lective towards the analyte to avoid sample matrix interference.


35/40

2207/WA/2013/

The flowrate and response time of the ISE orUV

etector affect the sample throughput (no. of analysis perour) of the auto-analyzer.

Symmetrical peak gives the least error in measuring peak

eight for concentration. Asymmetric peak require peak

rea for quantitation, more complicated and less accurate

measurement.The most efficient sample throughput is when the first

eak reaching baseline, the second peak will start with

minimal time between samples. Thus, FIA can handle

undreds of samples everyday. This can be done by

ptimizing the flowrate and mixing rate of the FIAystem.


36/40

2207/WA/2013/36

NaOH used as eluent

o meet the problem for determination of anions at ppm

vel, Two chemists working at from Dow Chemicals have

atented a suppressor technology in 1975 to enable the use

f conductivity detector to detect non-UV active anions like

hloride and Sulphate after their separation by HPLC using

n Ion Exchange Column. They left Dow Chemicals to set

p a new company (Dionex) to expand the suppressor

chnology to determine anions at ppm level for acid rain

monitoring, taste in food, impurities in DI water and for

arious industrial monitoring, leading to the birth of aillion dollar industry for Ion Chromatography at California

) ION CHROMATOGRAPHY

OH- +H+ H2O Low Background Conductivity

SO4= +H+ H2SO4

Strong acid, high conductivity

(1)

(2)

1) + (2) High Detection Sensitivity

-Patent by DIONEX i

based on suppressor

technology which is

expired in 2005.

Suppressor


37/40

Ion

Chromatogram

using Suppressor

Column for ppm

determination ofanions in water

Fung & Dao, Anal.

Chim Acta, 1995,315, 347.

2207/WA/2013/37

Non-suppressed Ion

hromatographyNon-suppressed IC)

Same as IC except

o suppressed column

sed, Use weak

rganic acid as eluentwhich absorb UV for

ndirect UV detection

f non-UV absorbing

nions to avoid patent

n suppressor.


38/40

After suppressor patent is expired, other companies enter

he IC market, producing cheaper & better design with

utomatic/onsite regeneration of suppressor column

1) Running IC Column For Anions

Separation & Quantitation

2)On-column Suppressor Regeneratio

Dual Cycle with one

uppressor in use and

he other regenerated

07/WA

013/38

Flowchart For MMS III Membrane Suppressor

To stay ahead in IC

chnology, DIONEXeveloped Membrane

uppressor (patent still

n force) to reduce post-

olumn band broadening,

nable continuous insitu

uppressor regeneration &

chieve ppb detection level.


39/40

Another direction taken by

IONEX is coupling IC

Membrane suppressor

perated by applying +/

oltages across membrane

remove H+ and OH-

2207/WA/2013/39

Eluent

(NaOH)

Membrane

Membrane

Regenerant (H2SO

electrolytic H2O)

Regenerant (H2SO4electrolytic H2O)

Sample (NaF,

NaCl, Na2SO4)

reduce thyroi

hormone

production

ii)USEPA

Max level at

1 ppb in drinkin

water in 2002

iii)IC2pp

QL at 100

iv)IC/MS/MSD

4ppt(ng/L) for 99/8

MRM at 100L

v)MRM confirmation for37Cl/35Cl at 0.323 ratio

with MS

detector to

nable ppt

detection of

nion andonfirmation

f anion (ClO4-)

n milk & water

i)High ClO


40/40

SUMMARY

1) For water analysis, it is always under

government control based on standards,

guidelines or objectives.

2) Analytical method should have detection limits

at 10 % or lower of the quantitation limit at

guideline values. Do not need extreme sensitivity.

Method should be fit-for-purpose.3) Cost is always important for water analysis, as

a lot of data are collected on daily basis. There is a

trend towards methods capable of analyzing

multi-parameters.

4) Validity of method is important. Thus, standard

methods are often used with calibration by

reliable standards.

5) High degree ofautomation in analytical

method in water analysis. Future methoddevelopment is towards integration with field

sampling and laboratory analysis, as results

should represent condition in field and many

2207/WA/2013/40

water analysis.pdf

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