real-time water quality monitoring systems: uv-vis ... · real-time water quality monitoring: the...

Real-Time Water Quality Monitoring: The Vienna Experience

www.s-can.at

© s::can Messtechnikp.1

Real-Time Water Quality Monitoring Systems:UV-Vis Spectrometry

andThe Vienna Experience (Part 2)

Real-Time Water Quality Monitoring WorkshopSt. John's, June 16th and 17th, 2009


www.s-can.at


0.5-5mm (waste water)+ waste water: ppm to g/l

+ sewer system

+ processes / industries- paper

- vine

- beer

- juices

- oils

- petrochemical

- biotech

- …………..

100 mm (ultra sensitive)+ water monitoring: low ppb- drinking waters: alarm + protection /

security / distribution system

- ground waters (organiccontamination)

- sea water- low turbid drinking waters- ultra pure waters

+ processes / industries- cooling waters- pharma- electronics industries

35 mm (sensitive)+ general water

monitoring: ppb to ppm

- river water, bank filtrate

- sea water

- groundwater, -recharge

- drinking waters

- compliance of WWTP

- treatment processes

+ alarm / early warningsystems

s::can Online Spectrometers – for Almost Every Application


www.s-can.at


s::can Online Spectrometer – How Does It Work

Lampen-Steuer-elektronik mit Xenon Blitzlampe

lamp controlelectronics withXenon flash lamp

256 pix array detector with µ-processor electronics

256 pixel array Detektor mit µ-Prozessor Elektronik

Str

ahls

elek

tor

be

am

sele

cto

r

Em

pfan

gsop

tikcolle

cting o

ptics

Sen

deop

tikem

itting o

ptics

Meßstrahlmeasuring beam

Referenzstrahlreferencing beam

Ein

sätz

e zu

r V

erkü

rzun

gde

s M

ess-

Pfa

des

insert

s fo

r ad

apta

tion

of optical path

Rei

nigu

ngsd

üse

ncle

anin

g n

ozzle

s


www.s-can.at


• For concentrations ranging from ppb (drinking waters) up to g/L (industrial waster waters), UV-Vis spectrometry has established as a leading method for in-situ concentration monitoring of:

• Nitrate and nitrite (far superior to ISE)

• Turbidity and / or suspended solids (NTU_eq, FTU_eq, TSS)

• Organic parameters (UV254, COD_eq, TOC_eq, DOC_eq)

• Process specific parameters

• Water quality changes, alarms, event detection (EDS)

• Some more specific parameters are (amongst others):

• B, T, X; Phenols

• Hydrocarbon Alarm

• H2S

• Ozone

• and many more

Online Spectrometry - Introduction


www.s-can.at


• there is absolutely no wear

• there is absolutely no instrument drift because of 2-beam system

• the only two issues to care for is: 1) good installation 2) keep windows clean (several auto-cleaning options)

• we recommend one zero check per year, but many instruments are never set zero during many years of operation

• big difference to any other online sensor: It does NOT loose itscalibration, and no re-calibration necessary after eventual initial local calibration ….

• except the water completely changes its characteristics - which can be the case in waste waters, but not in river waters.

• if probe does not agree enough with lab (or other way round), this is very rarely a problem of calibration but of a) installation b) windows not clean c) reference procedure d) technical fault



www.s-can.at


• UV-Vis Spectrometry makes use of the wavelength-specific light absorption caused by (groups of) substances.

• Simple principle: Nitrate is just another (invisible) color. If our eyes were sensitive in the UV, we could “see” Nitrate and distinguish it i.e. from Nitrite, like we distinguish any other colors ! (But UV would destroy our eyes).

• Not all organics and ions absorb light, but many. Estimate is that 60 to 80 % of the organics measurably absorb light.

• s::can spectrometer probes represent today’s most simple and natural way of any to monitor the composition of water. Simpler than a pH sensor.

• No chemicals, no reagents, no membranes, no wear, no moving parts in the water, most tolerant installation, low power consumption, etc.

• One year of unattended operation feasible. Just keep windows clean / auto-clean / and nothing else to take care for.



www.s-can.at


Online Spectrometry – The Measuring Principle

Old UV-probes: 1 wavelength only


www.s-can.at


Online Water Quality Monitoring & UV/Vis Spectrometry

© s::can Messtechnik GmbH


www.s-can.at


Appl. "INFLUENT" - COD [mg/l]

R2 = 0,94

0

100

200

300

400

500

0 100 200 300 400 500

s::can CODeq [mg/l]

Labo

rato

ry C

OD

[mg/

l]

Appl. "INFLUENT" - COD [mg/l]

R2 = 0,52

0

100

200

300

400

500

100 200 300 400 500

Single wavelength [Abs/m]

Labo

rato

ry C

OD

[mg/

l]

Application "RIVER" - NO3-N [mg/l]

R2 = 0,93

0

2

4

6

8

10

0 2 4 6 8 10

s::can NO3-Neq [mg/l]

Labo

rato

ry N

O3-

N [m

g/l]

Application "RIVER" - NO3-N [mg/l]

R2 = 0,28

0

2

4

6

8

10

0 20 40 60 80 100

UV230nm [Abs/m]

Labo

rato

ry N

O3-

N [m

g/l]

Why is Spectrometry Better than Single Wavelength ?


www.s-can.at


Application "MILK" - COD [mg/l]

R2 = 0,98

0

2000

4000

6000

8000

0 2000 4000 6000 8000

s::can CODeq [mg/l]

Labo

rato

ry C

OD

[mg/

l]

Application "MILK" - COD [mg/l]

0

2000

4000

6000

8000

50 100 150 200

UV254nm [Abs/m]

Labo

rato

ry C

OD

[m

g/l]

Application "PAPER" - COD [mg/l]

R2 = 0,96

0

500

1000

1500

2000

0 500 1000 1500 2000

s::can CODeq [mg/l]

Labo

rato

ry C

OD

[mg/

l]

Application "PAPER" - COD [mg/l]

R2 = 0,73

0

500

1000

1500

2000

100 200 300 400 500

UV254nm [Abs/m]

Labo

rato

ry C

OD

[mg/

l]



www.s-can.at



0%

5%

10%

15%

20%

25%

9:00 12:00 15:00 18:00 21:00 0:00 3:00 6:00 9:00

Per

cen

tual

Ab

solu

te D

evia

tio

n

abs error Hach NOx-N

abs error s::can NOx-N

XXXXXXXX… simple NO3-UV-Probe

s::can nitro::lyser


www.s-can.at



Regressions, calibrated

Hach: R2 = 0,9121

s::can: R2 = 0,9849

0,00

1,00

2,00

3,00

4,00

5,00

0,00 1,00 2,00 3,00 4,00 5,00

NOx-N, Lab

NO

x-N

, Sen

sor

Hach, calibrated

s::can, calibrated

simple NO3-UV-Probe:(calibrated)

(calibrated)


www.s-can.at


Fließgewässer-überwachung:

- Alarmsysteme- Frühwarnsysteme

- SAK- DOC_eq- Nitrat_eq- KW_eq- Trübung

254 (280, 436 etc.)

"Eignung von Rohwasser zur Gewinnung von Trinkwasser"

Überwachung derUferpassage- Filterwirksamkeit- Überwachung der Trübe incl. Feintrübe/Kolloide- Alarm bei spezifischen und unspezifischen Überschreitungen- DOC_eq.- Nitrat_eq.- KW_eq.

Brunnenüberwachung- Grundsätzliche Eignung zur Trinkwassergewinnung- Trübung- Alarm- DOC_eq- Nitrat_eq- KW_eq

Überwachung, Betrieb und Steuerung derAufbereitungsanlage- Trübung- DOC_eq.- Ozon- Veränderungen des OC bei der Oxidation- Oxidations-Folgeprodukte- Filtereffizienz/-durchbruch- Adsorption/-durchbruch- Flockung / Trüb. / OC- Nitrat_eq.- div. Einzelsubstanzen- spektrale Überwachung

Überwachung, Betriebund Steuerung derGrundwasser-anreicherungsanlage:- Trübung- DOC_eq- Nitrat_eq- Einzelsubstanzen_Alarm- qualit. spektrale Kontrolle

Überwachung desVerteilnetzes:DOC_eq.Nitrate_eq.Trübunghygienisches RisikoEinzelsubstanzen_Alarm


www.s-can.at


Headline

Water in Vienna

Brief history of Vienna and its Water

Vienna Area Urban Settlement since Roman Times

• First start of modern distribution network in the 16th century, and first modern sewers in the 17th century

• As center of the Austro-Hungarian empire Vienna grew from 270.000 to > 2.100.000 inhabitants in 1800 – 1910

• To ensure water supply new infrastructure was needed –realised in the form of 2 aquaducts between 1873 & 1910

• Water supply and treatment still being expanded and modernised


www.s-can.at


Water in Vienna

• Main source for Drinking Water are mountain springs in carstic rock formations

• The water from individual sources is collected and transported to the city using two aqueducts (over 280 km)

• A number of back-up sources has be established, but spring water is still the main supply

• Water is used without any purification other than sometimes little chlorine (no residual at tap)

• Important: carstic water sources are sensitive to extreme weather conditions, heavy rainfall can affect water quality

• online control of sources is necessary to ensure continuous highquality water


www.s-can.at


Headline

Vienna‘s Drinking Water Supply System


www.s-can.at


Headline

Monitoring at Vienna Waterworks

• Until 2001, only a small number of major springs monitored online

• mainly physical parameters & SAC254

• expensive stations

• Since 2001, a network of > 30 stations including spectrometer probes, pH, and conductivity established by s::can

• Data collected by central network and accessible from 3 control stations

• Many springs in remote locations -no infrastructure apart from mains power

For commissioning

• Multi Instrument inter-comparison verificationscrucial before service acceptance of multiple probes

• Inter-comparison with other measurement techniques (turbidity, SAC254) performed


www.s-can.at


Headline

Vienna Drinking Water

Testing:

0.040.0010 – 0.41SAC254

(abs/m)

0.010.0250.78 – 0.93Nitrate

(mg/L)

0.240.180 – 1.75Turbidity

(FTU)

95% conf.

interval

Median of

difference

Measured

range

Parameter


www.s-can.at


Headline

Vienna Drinking Water

07.06 09.06 11.06 13.06 15.06

Date

Tu

rbid

ity,

SA

C, C

on

d. Turbidity

SAC

Conductivity


www.s-can.at


Headline

Into Vienna‘s Sewer System

In total 2200 km of sewer draining 260 km2

Issues

• water quality monitoring

• corrosion control and odour management

Operational challenges

• highly variable flow conditions

• mechanical damage

• corrosion

• explosive atmosphere


www.s-can.at


Headline

Sewers applications

Corrosion and Odour control – Hydrogen Sulphide

Two methods:

• nitrate measurement

• sulphide measurement (UV + pH)

R2 = 0,95

0

2

4

6

8

10

12

14

16

18

0 2 4 6 8 10 12 14 16 18

s::can NO3-Neq (mg/l)

Lab

ora

tory

NO

3-N

(m

g/l)


www.s-can.at


Headline

Vienna Waste Water Treatment Plant

Main treatment plant:

• responsible for 4 million person eq.

• can treat 680 000 m3 / day

• expanded and modernised in 2003 - 2005


www.s-can.at


Headline

WWTP applications

Spectrometery at the WWTP

30 Instruments used for:

• measurement of COD, NO3 and TSS in plant Influent

• TSS and NO3 in primary and secondary aeration basins

• control of sludge recycling by nitrogen measurement in secondary aeration

• special algorithm used to measure NO3 without cross-sensitivity to Iron Chloride

• Using pressure air cleaning, no regular maintenance is required, apart from periodical visual inspection and trivial cleaning of optical surfaces


www.s-can.at


HeadlineSpectrometery at the WWTP

avg difference between probes: < 0.8% or 0.17 mg/L

WWTP applications


www.s-can.at


The Danube – river water monitoring


www.s-can.at


0

5

10

15

20

25

30

35

40

11.09. 14.09. 17.09. 20.09. 23.09. 26.09. 29.09. 02.10. 05.10. 08.10. 11.10.

Tu

rbid

ity

[FT

U],

div

. DO

C [

mg

/l]

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

dan

ub

e d

isch

arg

e [m

³/s]

Turbid [FTUeq] Cabinet Analyser DOC [mg/l]s::can DOCeq [mg/l] Q [m3/s]


• Turbidity follows flow

• DOC reacts later and less pronouncedthan turbidity

• spectro::lyser DOC is smoother and more accurate than cabinet analyserDOC, which is too cross-sensitiveagainst turbidity


www.s-can.at



Turbidity - Time Series in River Water

0

10

20

30

40

50

60

70

17.7.000:00

19.7.000:00

21.7.000:00

23.7.000:00

25.7.000:00

27.7.000:00

29.7.000:00

31.7.000:00

2.8.000:00

Time [DD.MM.YY hh:mm]

Tu

rbid

ity

[F

TU

]

0,0

Zülig

s::can


www.s-can.at


Headline


R2 = 0,992

0,5

1,0

1,5

2,0

2,5

3,0

0,5 1,0 1,5 2,0 2,5 3,0

DOC [ppm]

s::c

an D

OC

eq [

mg

/L ;

pp

m]


www.s-can.at


Headline

Groundwater Recharge

New hydropower plant built by VERBUND – Austrian Hydro Power AG

Sealing wall constructed to prevent excessive infiltration of surface water

This reduces the natural dynamics of the ground water, which is actively compesated by:

• artificial recharge with bank filtrate water• tranfer from infiltration wells back to the Danube

• transfer of water is stopped in case of bad quality

Six monitoring stations have been built to safeguard the water hydrodynamically affectedby the power plant.


www.s-can.at


Headline

Bank filtrate monitoring

• In this application the spectrometer probes are used for monitoring the composition of the bank filtrate water

• DOC by UV absorption is used as the control parameter

Long term tests have shown:

• high availability of the instruments• precision of measurements much

higher than with TOC analyser

• allows detection of extremely small changes


www.s-can.at


Headline


DOC_eq


www.s-can.at


Influence of nearby river on ground water quality



www.s-can.at


Change of spectral properties during bank filtration



www.s-can.at


Spectrometry for online & in-situ water quality monitoring

• optical technique offers high precision low maintenance instruments

• allows one instrument to perform many tasks in widely varying applications

• has become a fundamental part of Vienna’s Water Quality Management

• successfully applied in sewers for corrosion prevention

• has proven its value for process control of WWTP

• used to monitor and manage natural waters

Summary & Conclusions


www.s-can.at


Thank you for your attention!

s::can Messtechnik GmbH

Brigittagasse 22-24

1200 Vienna, Austria

Tel: +43 1 219 73 93

E-mail: [email protected]

www.s-can.at

real-time water quality monitoring systems: uv-vis ... · real-time water quality monitoring: the...

Documents