Introduction
Evaluating sorption and degradation
characteristics of pesticides using column
displacement experiments
Tineke DE WILDE
Farm run off

driftdrainage

Precipitation run off

Problem: Direct losses

Bioremediation systems: state of the art

BIOBEDBIOFILTER
EVAPORATIONPHYTOBAC
Storage tankplastic - concrete

re-useBlack box

Bioremediation systems: state of the art

CH3
Cl

BIOBEDClClCl

ClCl

ClO
SO

CH3O

O

Cl

PHYTOBAC(CH3)2CHNHCONOCH3CH2
CH3OC

NHCON(CH3)2CH3
NCH

CO2CH3CH3

Humification, sorption,
degradation, mineralization ??

• Predict the behaviour of pesticides in the system• Optimization of the system based on theknowledge of the molecule and the quantity ofwaste water
Knowledge about the risks involved

BIOFILTER

Reference pesticides

Substrates
6Criteria
6 Availability
6 Price
6 Nutrient content
6 OM
6 C/N
6 pH
6 EC

Coconut chips
Sandy loam soil

Dried cow manure

Green waste
compostWillow branches

Peat mix
StrawTransport of pesticides
6Displacement of a solute in solutions is simulated by theconvection dispersion equation (CDE)R∂c∂ 2c∂c= D 2 − v − µl c∂t∂z∂z R: retardation coefficient

R = 1+ ρ: bulk density (kg/l)

Monod kinetics
Concentration

Biomass

ρK nC n −1θ f θ: volumetric moisture content
 Kf, n: Freundlich parameters v: pore water velocity (cm/d)
 D: dispersion coefficient (cm2/d)

 μl : degradation constants (d-1) in liquid and solidphasedX ⎛c ⎞= ⎜ μm
⎟ X − kdecay X
dt ⎝Ks + c ⎠dX ⎛ μm ⎞c ⎟ X − kdecay X = ( μm* c ) X − kdecay X=⎜dt ⎝ K s ⎠dc1⎛c ⎞= − ⎜ μm
⎟Xdt
Y⎝Ks + c ⎠⎛ µ⎞dc= −⎜⎜ m X ⎟⎟c = −( µ * X )cdt
⎝ YK s ⎠∂cX = ρ X s + θ X l = ρ K d X l + θ X l = ( ρ K d + θ ) X l = θ RX lwhere ρ is the soil bulk density [ML-3], θ is thewater content [L3L-3], Kd is the distribution
coefficient [L3M-1], R is the retardation factor [-],and Xs and Xl are biomass concentrations in thesolid and liquid phase.
The distribution coefficient Kd must be selected tohave a large value (e.g., 10,000) so that biomass
stays in place and the convective flux can beneglected.

∂ 2c

∂c

Transport equation: R ∂t = D ∂z 2 − ν ∂z − ( μ X )c

HYDRUS implementation
Simulation carried out with 2 solutes: pesticideconcentration and biomass
The biomass X is defined as:

If c <<Ks*Column experiments
25 % sandy loam soil

125 % sandy loam soil

125 % peat mix

50 % straw

225 % sandy loam soil
20 % peat mix

25 % compost

5 % cow manure

50 % straw

50 % straw= klassieke biomix

25 % coco chips
25 % sandy loam soil

425 % coco chips
25 % sandy loam soil
5 % cow manure

25 % peat mix

25 % straw

20 % peat mix

25 % straw

53

Isoproturon

1,0Column experiments – set-up

A calculated
A experimental
B calculated
B experimental
C calculated
C experimental

0,8C/C0

0,60,4θ
0.58 ± 0.02
0.54 ± 0.02
0.62 ± 0.02
0.54 ± 0.02
0.63 ± 0.03

12345Dcm
1.97 ± 0.28
1.41 ± 0.18
2.54 ± 0.284.03 ± 0.45
2.03 ± 0.39

R²1.

0,20,00.90
0.92
0.89
0.92
0.77

051015MixKfL kg-1

n-µl (x 10-3)
h-1

RR²

123
45

8.00 ± 0.39

1.02 ± 0.04

2.23 ± 0.17

12.07 ± 2.01

0.99

3.70 ± 0.19

1.31 ± 0.02

2.40 ± 0.12

15.39 ± 3.37

0.99

4.93 ± 0.03

1.04 ± 0.03

1.70 ± 0.08

7.20 ± 0.86

1.00

5.11 ± 0.07

1.04 ± 0.07

1.87 ± 0.15

7.97 ± 1.72

0.99

2.05 ± 0.03

1.32 ± 0.08

2.01 ± 0.11

7.36 ± 2.140.98

20PV1,0A calculated
A experimental
B calculated
B experimental
C calculated
C experimental

0,80,6C/C0

Flow 1.74 cm/d ~ Biofilter (1 m³) = 114 l/d0,4Î Pesticides: metalaxyl, bentazon, linuron, isoproturon

0,2Î Concentration: 10 mg/l

0,0

2.
0

510

Î Inerte tracer Br- added as a puls

1520PVÎ Estimated hydraulic parameters: θ and D

1,0Î Estimated transport parameters CDE model: Kf, n and µl0,8

Î Estimated transport parameters CDE model with Monodkinetics: µ*m, µ* and Kdecay

1,0A calculated
A experimental
B calculated
B experimental
C calculated
C experimental

1,0A calculated
A experimental
B calculated
B experimental
C calculated
C experimental

0,80,6C/C00,40,43.

0,2

510

15

200,00510PVBentazon

1,0

1.

0,810

15

C/C0

C/C0Mix
20PV

123
4
51,21,0

C/C00,80,60,4

A calculated
A experimental
B calculated
B experimental
C calculated
C experimental

2.

0,2R0,2Kfnµl (x 10-4)

R²L kg-1-h-1

0.00 ± 0.00

4.78 ± 2.14

3.11 ± 4.64

1.10 ± 0.17

0.90

1,00.02 ± 0.02

2.55 ± 0.41

5.18 ± 6.43

1.00 ± 0.00

0.91

0,80.01 ± 0.02

3.15 ± 0.85

1.82 ± 2.83

1.03 ± 0.02

0.72

0,60.01 ± 0.03

3.61 ± 1.06

3.25 ± 1.49

1.27 ± 0.33

0.85

0.02 ± 0.02

2.02 ± 0.43

0.00

1.06 ± 0.10

0.92

0,00

515200,4A calculated
A experimental
B calculated
B experimental
C calculated
C experimental

0,21015020

5100,80,80,6A calculated
A experimental
B calculated
B experimental
C calculated
C experimental

0,60,4A calculated
A experimental
B calculated
B experimental
C calculated
C experimental

4.

0,20,0510PV15200,60,4

A calculated
A experimental
B calculated
B experimental
C calculated
C experimental

5.

0,20,00µ* (x 10K -7)µm* (x n10-4)-3µl (xk10decay )RR²YR²9.15 ±L 14.02
kg-1-0.18 ± -8.21-6-3
3.15·10h-1 ± 7.01·10

0.96

20.20

2c

13.43 ± 2.92-2.11 ± 1.93

1.08·10-3 ± 1.37·10-3

0.96

156.893a9.99 ± 0.89

-5.27 ± 1.09

2.57·10-3 ± 6.22·10-4

10.95 ± 3.96

-0.98 ± 3.23

2.30·10-5 ± 2.01·10-3

4.55 ± 0.15
4.62 ± 0.95

0.78 ± 0.02
-2.42 ± 1.41/
3.69 0.98± 0.606.26·10-4 ± 1.06·10-3

524.841.37± 0.283.38± 0.651.58±±0.99
0.01-3.95

1.26 ±-4 0.09
± 1.495.27·10± 4.88·10-4 8.51 0.93

0.961168.182.82± 0.444.43± 0.700.76±±0.54
0.09-2.69± 0.934.90·10/-8 ± 2.14·10-4 2.76 0.91

0.70607.71

1.99 ± 0.25

-2.51 ± 0.93

1.12·10-7 ± 4.30·10-4

1266.12f

3.39 ± 0.37
2.26 ± 0.53

1.17 ± 0.05
1.02 ± 0.11

1.38 ± 0.12

7.54 ± 1.76/

6.52 ± 3.97

0.99

0.96

527.39

0.86

89.66

0.97
0.92

0.90

20510PV

15

20

1,00,80,80,60,60,4

3.

0,00510PV

15200,80510PV15A calculated
A experimental
B calculated
B experimental
C calculated
C experimental

4.

0,20,45.

0,20,020

A calculated
A experimental
B calculated
B experimental
C calculated
C experimental

0,60,4A calculated
A experimental
B calculated
B experimental
C calculated
C experimental

0,20,00

1,0

C/C00,83.

15

C/C0

1,0

C/C0

1,21,0C/C01,21,00,220

PV1,20,4152b5c0,0510Mix
Mix
123b33c5a45b52.

PVC/C010PV0,005PVC/C05C/C01.
0

A calculated
A experimental
B calculated
B experimental
C calculated
C experimental

0,40,00

Metalaxyl

0,60,220

1,00,6
A calculated
A experimental
B calculated
B experimental
C calculated
C experimental

15

PV0,80,4

A calculated
A experimental
B calculated
B experimental
C calculated
C experimental

0,20,00

1,20,4

4.

0,20,05.

0,80,6

C/C00,6C/C0

Mix0,00510PV15200510PV

1520

LinuronNo breakthrough during the whole experimentThank you for yourattention!!

Conclusion column experiments
Mobility (Koc) is a good indicator for theleaching through a column
Leaching potential: bentazon > isoproturon ≈metalaxyl > linuron
Composition of the matrix has a limited
influence on leaching and degradation
Addition of cow manure could increasedegradation ?
Modified Monod kinetics fits degradation of
metalaxyl in 3 mixtures
Determination sorption coefficient by batch
experiments Î overestimation