We deliver Phosphorus made in
Europe
Recovery of Phosphorus from Sewage Sludge and
Subsequent Purification Using Reactive Extraction
17th SFGP Congress, 15-17.10.19, Nantes, France
Pfennig A., Shariff Z.A., Fraikin L., Léonard A.
agenda
• introduction
• PULSE process concept
• process development
– SLE modelling
– cascaded option tree
• experimental results
• demonstrator
introduction
• essential element for all forms of life & finite
resource
• more than 80% P produced used in
agriculture
rock phosphate
EU sourcing (domestic production + imports)
of phosphate rock, average 2010-2014
introduction: EU crictical
materials
introduction : fraction of
P-loss in waste for EU-27
Kimo C. etal., 2016. Phosphorus flows and balances
of the European Union Member States, Science of
The Total Environment, Volume 542, Part B
introduction : P recycling
• P-recovery potential from sewage sludge for EU >
25%
• German legislation (2017) – either recovery of P >
50% or reduction of P in sewage sludge to <2% by
2029
• new EU fertilizer regulation: certain types recycled P
allowed to be used in fertilizers
(published June 2019)
– first EU product legislation to confer “End of Waste”
status
introduction: Phos4You project
• accelerate the exploitation of P
recovery in sewage and close the
gap
between
P-recovery
and
recycling.
• 12 partners from 6 EU member
states and Switzerland
• demonstrate 7 P-recovery
technologies
• ULiège: demonstrate PULSE
process and LCA for all the
technologies
introduction : Phos4You
demonstrator
country
source
process
EuPhoRe GmbH
Germany
(digested)
sludge
pyrolysis followed by
incineration
Lippeverband with
REMONDIS Aqua
Germany
sewage sludge
ashes
chemical leaching
followed by ion-exchange
PULSE process, ULiége
Belgium
dried sludge
chemical leaching,
reactive extraction,
precipitation
IRSTEA and Véolia
France
sewage sludge bio-acidification,
ion-exchange, precipitation
Veolia with CIT and GCU
France
wastewater
precipitation
GCU
Scotland
wastewater
P uptake by algae
ERI and Veolia
Scotland
wastewater
adsorption of P
PULSE (Phosphorus University of
Liege Sludge Extraction) process
acid
organic
solvent
base/Ca
drying
leaching
separation
reactive
extraction
re-extraction
CaP
solid
waste
metals
precipitation
dewatered
sludge
waste
water
re-extraction
agent/NH
3
P + impurities
PULSE process development
PULSE process concept – based
on PASCH process (TU Aachen)
design and construction of PULSE
demonstrator
• experiments to evaluate
process option/parameters
• modelling tool development &
validation
cascaded option trees evaluation –
final PULSE process
PUSLE demonstrator operation
inputs from quality assesment &
LCA
optimization with lab experiments
& modelling
scale up design of PULSE
technology
modelling: Solid-Liquid-Liquid
Equilibrium
• aqueous phase speciation:
– mass balance
– law of mass action
– charge balance
• solid precipitation:
– saturation index
• activities instead of concentration to account for ionic
interactions
• efficiency of reactive extraction with organic solvents
modelling: SLE & speciation
-1
0
1
2
3
4
5
6
7
8
9
1E-6
1E-5
1E-4
0.001
0.01
0.1
1
CaHPO
4FeCl
4-FeHPO
Fe
2+PO
43-CaHPO
4(S)
AlPO
4(S)
FePO
4(S)
CaH
2PO
4+FeH
2PO
42+H
3PO
4H
2PO
4-HPO
42-FeH
2PO
4+Ca
2+Cl
-Al
3+Fe
3+con
cen
tra
tion
mo
l/l
pH
modelling tool: non-linear data
fitting
1
10
0.0
0.2
0.4
0.6
0.8
1.0
de
gr
ee
of
iro
n e
xtra
ction
usin
g A3
36
+T
BP
Cl
-concentration mol/L
model
measured
cascaded option tree: drying
P-recovery
from sludge
drying
conditions
- dewatered sludge
0 0 0
-+ convective air drying
+ 0 0 0 0
slow drying (no air)
+
0 0 0
extraction compatibility
filtrability
P leaching
operation cost
transport/handling/storage
not evaluated
Bednarz, A. et al. 2014. Use of Cascaded Option Trees in
Chemical-Engineering Process Development. Chem. Ing. Tech. 86, 611-620
- not feasible
0 acceptable
+ good
sludge drying
dried sludge (>95% DM)
dewatered sludge (20-22% DM)
• biologically unstable – storage /
transportation issues
• pasty – requires 2 -3 times more water/acid
for leaching (0.06€/mol acid)
• difficult to filter at low pH
• stable solid – easier storage / transportation
• mineral like – less water / acid for required
for leaching (drying cost = 0.1 – 0.21 €/kg
dewatered sludge)
P leaching- wet/dry sludge
0.0
0.2
0.4
0.6
0.8
1.0
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
rapid convective drier with air circulation (65 - 98% DM)
wet sludge (2 - 21% DM)
slow drying 80 -100°C (>98% DM)
oven dried without air circulation 105°C (>98% DM)
de
gr
ee
of
P lea
ching
pH
P leaching- different acids and pH
-1
0
1
2
3
4
5
6
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
de
gr
ee
of
P lea
ching
equilibrium pH
HCl
H
2SO
4HNO
3HCl+HNO
3HCl+H
2SO
4HNO
3+H
2SO
4H
3PO
4model
P leaching- organic & inorganic P
*According to The standards, measurements, and testing (SMT) procedure for phosphorus
fractionation in freshwater sediments, developed within the framework of SMT Program of the EC
32.43%
67.57%
in organic fraction of P
organic fraction of P
sludge leach liquor
P Fe K Mg Ca Al Mn Zn Na Cr Cu Ni Co Pb Cd
0.1
1
10
100
1000
10000
cen
cen
tra
tion
(m
g/L
) in
lea
ch liq
uo
r
H2SO4
HCl
reactive extraction with HCl
conc. 1mol/L
D2EP
HA
TBP
D2EP
HA
-TBP
A33
6
6-
D2EP
HA
A33
6-
TB
P
D2EP
HA
-TBP
0
20
40
60
80
100
pe
rc
en
ta
ge
o
f e
xt
ra
ct
io
n
P
Ca
Cd
Cu
Pb
Zn
Fe
mixing
settling
Fe extraction with A336-TBP at
varying Cl
-
concentrations
Alamine 336:
𝐹𝑒𝐶𝑙
4
−
+
𝑅
3
𝑁𝐻
+
𝐶𝑙
−
=
𝐹𝑒𝐶𝑙
4
𝑅
3
𝑁𝐻
+
𝐶𝑙
−
TBP:
𝐹𝑒𝐶𝑙
4
−
+
𝑇𝐵𝑃
=
𝐹𝑒𝐶𝑙
4
𝑇𝐵𝑃
0
1
2
3
4
5
6
7
8
9
10
11
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
de
gr
ee
of
iro
n e
xtra
ction
Cl
-concentration mol/L
10%Al336
+10%TBP
(O:A=1)
10%Al336
+10%TBP
(O:A=2)
15%Al336
+15%TBP
+1%Exxal
15%Al336
+15%TBP
+1%Exxal
0.0
0.2
0.4
0.6
0.8
1.0
de
gr
ee
of
iro
n e
xtra
ction
Fe extraction with different extractant
Fe extraction extraction with
and without H
2
O
2
before
extraction
after
extraction
0
1
2
3
4
5
no H
2O
2Fe
2+Fe
3+tot
al iro
n co
nce
ntr
atio
n g
/L
before
extraction
after
extraction
with H
2O
2Fe
3+Fe
2+reactive extraction of Fe with
A336 + TBP
1
2
3
4
5
6
7
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
extraction without H
2
O
2
extraction with H
2
O
2
de
gr
ee
of
iro
n e
xtra
ction
-
Alamine 336:
𝐹𝑒𝐶𝑙
4
−
+
𝑅
3
𝑁𝐻
+
𝐶𝑙
−
=
𝐹𝑒𝐶𝑙
4
𝑅
3
𝑁𝐻
+
𝐶𝑙
−
TBP:
𝐹𝑒𝐶𝑙
4
−
+
𝑇𝐵𝑃
=
𝐹𝑒𝐶𝑙
4
𝑇𝐵𝑃
re-generation of solvent
after centrifugation
before
mixing
during
mixing
phase
separation
organic solvent
+ metals
aqueous phase
(NH
3
+ NH
3
HCO
3
)
regenerated
organic solvent
aqueous phase +
metal precipitates
2 stage extraction before
precipitation of product
P
Fe
0
1
2
3
4
5
after
2nd
extraction
after
1s
t
ex
traction
con
cen
tra
tion
g/
L
raw liquor
PULSE product
Comp.
PULSE
Legislative
limit
P
2
O
5
29.2%
> 3 %
CaO
21.7 %
> 1.5 %
Total C
6 %
-Al
2
O
3
2.61 %
-MgO
1.84 %
> 1.5 %
Fe
0.325 %
-Mn
10800ppm
-Cr
1530 ppm
-Cu
294 ppm
600 ppm
Ni
51.6 ppm
120 ppm
Pb
38,8 ppm
150 ppm
Zn
8.97 ppm
-Cd
0.735ppm
60 ppm
Hg
0.054 ppm
2 ppm
leaching of dried sludge
filtration
metal removal by
reactive extraction
CaP precipitation with
NaOH (pH = 6 - 7)
P recovery potential
dried sludge
leaching
reactive
extraction
precipitation
0
20
40
60
80
100
137 g/kg
23 g/kg
P rec
ove
ry p
ote
ntia
l
inorganic P
organic P
total P recovery
summary
• no significant difference between P leaching from wet
or dry sludge
• P leaching depends only on pH and not on the type of
acid
• extraction of metals at low pH only achieved with
Alamine 336
• metals concentration in product is within the limits set
by the EU fertilizer regulations except in case of Cr
further work
• lab scale optimization
• construction of demonstrator – 100kg/day
of dewatered sludge capacity
• operation of demonstrator in Belgium,
Germany, Ireland and Scotland
further work: PULSE demonstrator
drying
+
crushing
leaching
+
filtration
reactive
extraction
precipitation
+ filtration
acknowledgements
• financing
– Interreg North-West Europe
– SPW Région Wallonne
• analytics
– Faculty of Bioscience Engineering, Ghent University,
Belgium
16th October 2019, Nantes | 17th
