M.N. Pons, S. Le Bonté, O. Potier

Laboratoire des Sciences du Génie Chimique, CNRS-ENSIC-INPL, Nancy

Adaptive Principal Component Analysis for toxic event detection

Introduction

New regulations:

treatment in adequate facilities of all incoming waters

stricter limits on effluent quality, on sludge

Crisis:

rainstorm

accidental release of toxic components

some may be forecast (fire water)

other not

A short selection of potential toxics

Heavy metals: Hg, Cr, Pb, Cd, Zn, Cu ...

Solvents: white spirit, ...

Pesticides

Herbicides

Motor fuels: diesel oil, ...

Detergents

Dyes

Introduction

New regulations:

treatment in adequate facilities of all incoming waters

stricter limits on effluent quality

Crisis:

rainstorm

accidental release of toxic components

some may be forecast (fire water)

other not

Improvement of plant control strategy

New scenarios

Introduction

Characterisation of wastewater composition COD, BOD5, SS NT, NH4

+, NO3-

PT, PO4-

K, Ca, Mg, ... Heavy metals (Cu, Zn, Cd, Hg, Cr, …) Micropolluants

Some are time-consuming Some are very specific

Introduction

Global (and faster) measurements temperature, conductivity, pH, redox turbidity light absorbance

fixed wavelength spectra

respirometry buffer capacity ...

On-lineIn-line (sampling)

Introduction

Three methods under test Respirometry Absorbance spectra Buffer capacity

Multivariate data analysis method

Validation on simulation

Experimental validation

Conclusions

Respirometry test: experimental set-up

Respirometry test

0

0,5

1

1,5

2

2,5

3

3,5

4

4,5

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Time (sec)

Dis

solv

ed o

xyg

en (

mg

/L)

-0,1

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

OU

Rex

(m

g/L

.min

)

DO probe

sludge + substrate

Typical response curves

Characteristic parameters

OUR curve

4 parametersMaximal value of Oxygen Uptake Rate

Oxygen volume (VO2) (5 or 15min)

Peak width

Initial slope

Experimental results

0123456789

0 500 1000 1500

temps (s)

[O2

]d (

mg

/l)

toxique

témoin

% de réduction de VO2 5 minutes

-20

0

20

40

60

80

0,00

20,

005

0,01

20,

024

0,23

50,

294

0,58

81,

176

1,17

61,

471

1,76

52,

353

2,94

13,

529

5,88

27,

353

7,35

38,

824

14,7

0629

,412

concentration en toxique en mg/l

% d

e ré

duct

ion

+ CuSO4

Experimental results

+ dye

2 respirometers in parallel

toxics added in one respirometer

VO2(mg/l)

0

0,5

1

1,5

2

2,5

3

3,5

4

4,5

5

7/6/ 4:00 7/6/ 8:00 7/6/ 12:00 7/6/ 16:00 7/6/ 20:00 8/6/ 0:00 8/6/ 4:00 8/6/ 8:00 8/6/ 12:00

témoin

avec toxique

CuSO4 NaOHHCl

White Spirit

javel

Gasoil

Experimental results

1

1,5

2

2,5

3

3,5

4

4,5

5

07/06/07:00

07/06/11:00

07/06/15:00

07/06/19:00

07/06/23:00

08/06/03:00

08/06/07:00

08/06/11:00

VO

2 (

mg

/l)

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

Ab

so

rba

nc

e

VO2 (mg/l)

A254nm

Experimental results

UV-visible spectrometry

0,00E+00

5,00E-01

1,00E+00

1,50E+00

2,00E+00

2,50E+00

3,00E+00

3,50E+00

200 250 300 350 400 450 500 550 600

Longueur d'onde (nm)

Ab

sorb

ance

220nm

254nm

270nm

546nm

0

1

2

3

4

5

6

7

8

9

200 250 300 350 400

Wavelength (nm)

No

rm.

ab

s

urea

nitrate

creatinine

urine

210

nm

220

nm

254

nm

270

nm

UV-visible spectrometry

Anthropogenic substances

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

200 250 300 350 400

Wawelength (nm)

No

rm. a

bs

orb

an

ce

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

UV-visible spectrometry

210

nm

220

nm

254

nm

270

nm Detergents

UV-visible spectrometry

0

0,5

1

1,5

2

2,5

3

3,5

200 300 400 500 600 700 800 900

longueur d'onde (nm)

Ab

sorb

ance

ABS (vert)

ABS(violet)

ABS(bleu)

ABS(jaune)

Dyes

UV-visible spectrometry

Norm. Abs0

0.5

1

1.5

2

2.5

3

3.5

4

21/3

/01

0:00

21/3

/01

12:0

0

22/3

/01

0:00

22/3

/01

12:0

0

23/3

/01

0:00

23/3

/01

12:0

0

24/3

/01

0:00

24/3

/01

12:0

0

25/3

/01

0:00

25/3

/01

12:0

0

26/3

/01

0:00

26/3

/01

12:0

0

210

220

254

270

546

Wednesday Thursday Friday Saturday Sunday

Abs. Abs

0.000

0.100

0.200

0.300

0.400

0.500

21/3

/01

0:00

21/3

/01

12:0

0

22/3

/01

0:00

22/3

/01

12:0

0

23/3

/01

0:00

23/3

/01

12:0

0

24/3

/01

0:00

24/3

/01

12:0

0

25/3

/01

0:00

25/3

/01

12:0

0

26/3

/01

0:00

26/3

/01

12:0

0

254

Wednesday Thursday Friday Saturday Sunday

Buffer capacity

Normally measured Wastewater pH Alkalinity

Here Acidification (pH 3) Titration to pH 11 Buffer capacity versus pH

pH = f(Vol.NaOH)

2

4

6

8

10

12

0 1 2 3 4

NaOH 0,1N (ml)

pH

Capacité tampon = f(pH)

0

0,2

0,4

0,6

0,8

1

3 5 7 9 11

pHC

apac

ité

tam

pon

(m

eq/

l/pH

)

dpHdCNaOH

Buffer capacity

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

3 4 5 6 7 8 9 10 11 12

pH

cap

ac

ité

tam

po

n

(mé

q/l/

pH

)

0h

2h

4h

6h

8h

10h

12h

14h

16h

18h

20h

22h

Bu

ffer

cap

aci

ty

Buffer capacity

Initial pH

7.17.2

7.37.47.57.6

7.77.87.9

25/2

0:0

0

25/2

12:

00

26/2

0:0

0

26/2

12:

00

27/2

0:0

0

27/2

12:

00

28/2

0:0

0

28/2

12:

00

1/3

0:00

1/3

12:0

0

2/3

0:00

2/3

12:0

0

3/3

0:00

3/3

12:0

0

4/3

0:00

4/3

12:0

0

pH=7.21 (phosphates)

0

0.02

0.04

0.06

0.08

0.1

0.12

25/2

0:0

0

25/2

12:

00

26/2

0:0

0

26/2

12:

00

27/2

0:0

0

27/2

12:

00

28/2

0:0

0

28/2

12:

00

1/3

0:00

1/3

12:0

0

2/3

0:00

2/3

12:0

0

3/3

0:00

3/3

12:0

0

4/3

0:00

4/3

12:0

0

Monday Tuesday W_day FridayThursday Sat_day Sunday Monday

pH=9.25 (ammonium)

0.2

0.30.4

0.5

0.60.7

0.8

0.91

1.1

25/2

0:0

0

25/2

12:

00

26/2

0:0

0

26/2

12:

00

27/2

0:0

0

27/2

12:

00

28/2

0:0

0

28/2

12:

00

1/3

0:00

1/3

12:0

0

2/3

0:00

2/3

12:0

0

3/3

0:00

3/3

12:0

0

4/3

0:00

4/3

12:0

0

Fault detection background

Univariate SPC MultivariateSPC

Overload of data

PLS

Partial Least Squares

Projection to Latent Structures

PCA

Principal Component Analysis

Continuous process (steady state)

Kresta et al. (1991): fluidized bed and extractive distillation column

Batch and Fedbatch

Lennox et al. (1999): Fermentation processes

?? Wastewater treatment plant = continuous process but not at steady state

Adaptive PCA

Diurnal cycle

1 sample / 30 min (48 samples / day) or / 1hr (24 samples / day)

4 Principal Variables (PVi) : Ourex max, Ourex T, Slope, Width ( 15 min)

In the case of 1 sample / 1 hr, the samples j to j+23 are used and 2 PCs are considered:

PC1 = 1PV1 + 1PV2 + 1PV3 + 1PV4

PC2 = 2PV1 + 2PV2 + 2PV3 + 2PV4

At sample j+24: prediction

PC1 (j+24) = 1PV1 (j) + 1PV2 (j) + 1PV3 (j) + 1PV4 (j)

PC2 (j+24) = 2PV1 (j) + 2PV2 (j) + 2PV3 (j) + 2PV4 (j)

At sample j+24: actual

PC ’1 (j+24) = 1PV1 (j+24) + 1PV2 (j+24) + 1PV3 (j+24) + 1PV4 (j+24)

PC ’2 (j+24) = 2PV1 (j+24) + 2PV2 (j+24) + 2PV3 (j+24) + 2PV4 (j+24)

Adaptive PCA

Prediction error = Detection (Q statistic)

SPE = [PC1(j+24) - PC ’1(j+24)]2 + [PC2(j+24) - PC ’2(j+24)]2

Update of i, i, i, and i using samples j+1 to j+24

Adaptive PCA

CP1 CP2

σ1, μ1

h

h+1

h+2

h+3

h+4

.

.

.

h+23

h+24

σ2, μ2

h+25

σ3, μ3 …etc

.

.

.

Effect of slow change in plant state

PCA on 24 previous samples (1 sample/hr),

estimation of actual sample

0,00

5,00

10,00

15,00

20,00

25,00

70 80 90 100 110 120

Time (hr)

Ou

rmax

, W

idth

-1,0

-0,5

0,0

0,5

1,0

1,5

2,0

2,5

3,0

VO

2, I

nit

ial

slo

pe

VO2

Width

Initial slope

Ourmax

-3

-2

-1

0

1

2

3

-3 -2 -1 0 1 2 3 4

0 a.m. d+1

1 a.m. d+1

2 a.m. d+1

12 a.m. d+1

1 a.m. d+2

f1

f2

night morning

noon

afternoon

evening

no toxic

toxic event

Why simulating ?

Unsteady state

Many factors to examine:

Location of sludge sampling

Ratio sludge / raw water

Quality of detection in function of the toxic conc. and nature, release time and type

….

Experiments on the real plant should be carefully selected

« Experiments » on a simulated plant

Plant layout

Incoming water to be tested

Secondary settlerExternal recycle

Aeration tank

Biomass sample

Biomass samplePrimary settler

Wastage flow

River

Biomass sample

Concentration of toxic

Release profile

0 0.07 0.17 0.11 0.16 0.23

0.1 0.07 0.58 0.42 0.34 0.22

0.5 0.07 1.49 1.37 1. 0.25

Concentration

De t

e cti

o n

Toxic release time

De t

e cti

o n

Release time

Release profile

Toxic release time

0,0

0,1

0,2

0,3

0,4

0,5

0,6

24 48 72 96 120 144 168

Time (hr)

Ou

r m

ax

0

0,1

0,2

0,3

0,4

0,5

0,6

To

xic

Tuesday Wednesday Thursday Friday Saturday Sunday

Detection = 1.49 (0.07) Detection = 2.77 (0.17)

Normal situation

-2

-1,5

-1

-0,5

0

0,5

1

1,5

2

-4 -2 0 2 4

f1

f2

2 p.m.

3 p.m.

4 a.m.

11 a.m.

Normal 24hr cycle:

dry weather

normal activity

Normal situation

5 initial variables : OURend, OURmax/A254, VO2/A254, width et A254

Critical situation: heavy metals

-2

-1

0

1

2

3

-4 -3 -2 -1 0 1 2 3 4

f1

f2

-2

-1

0

1

2

3

-4 -3 -2 -1 0 1 2 3 4

f1

f2

-2

-1

0

1

2

3

-4 -3 -2 -1 0 1 2 3 4

f1

f2

HgSO4

6 mg/l

30 mg/l

K2Cr2O7

6 mg/l

Critical situation: diesel oil

-2

-1,5

-1

-0,5

0

0,5

1

1,5

2

2,5

-6 -4 -2 0 2 4

f1

f2

4 a.m .

8 a.m .

12 a.m .

5 p.m .

5 a.m .

9 a.m .

10 a.m .

Addition of various amounts

of diesel oil

Critical situation: white spirit

-5

0

5

10

15

20

25

30

-4 -2 0 2 4 6

f1

f2

4 a.m.

8 a.m.

12 a.m.

5 p.m.

5 a.m.5 p.m.

11 a.m.

Addition of various amounts

of white spirit

very strong inhibition

Buffer capacity

4 initial variables : pH, β(pH=4,75),β(pH=7,21), β(pH=9,25)

SPE = [PC1(h) - PC’1(h+24)]2 + [PC2(h) - PC’2(h+24)]2

Buffer capacity

5-6 Nov.2001, 14h : Wastewater + citrate

UV-visible spectrophotometry

Conclusions

Global (and rapid) characterization of the composition of wastewaters

Absorbance spectra - Buffer capacity - Respirometry

+ Classical measurements (T, pH, rH, …)

+ flowrate + rainfall

Combined with statistical methods

Community activity (design, control, critical situation)We wish to thank

the Grand Nancy Council for its help GEMCEA, LCPC, NANCIE the students and colleagues

Plant model

2D models for the primary settler (Stokes) and the final clarifier (Takacs et al.)

Reactors in series with backmixing = f(flowrate, aeration rate)

Basic control on sludge wastage

IAWQ ASM 1 + inhibition :

growth rate of heterotrophs and autotrophs

death rate

degradation of toxic

Influent description

COST 624 Benchmark

Functions describing the Nancy WWTP effluent

Respirometer model FORTRAN code on PC