1. Phosphogreen™ technology
Nätverksträff för fosfor och andra avloppsresurser
Stockholm, December 2017

2. Presentation
Peter Balslev, wastewater specialist
Suez Water A/S

3. Phosphorus is a limited ressource

4. Phosphorus means problems at sludge handling
Piping
Digester wall
50 m3 "sand" in digester

5. Mass balance, 0% recovery - “before situation"
Pct. of inlet total-P
FeCl3
inlet
100
141
outlet 4
WWTP 4%
137
Return sludge 41
Pre-dewater
Digester
132 5
rejekt 36
Sludge 96
Final dewat.
96% 5

6. Phosphogreen™ Functionality
Process control
Magnesium chloride is dosed flow proportional into the reactor inlet together with inlet reject water, dosing is regulated based on analysis of PO4 weekly
NaOH is dosed into the reactor controlled by pH measurement – to keep pH value around 7.5,
Air lift pump secures internal recirculation as well as CO2 stripping
Internal recirculation pump secures up-flow velocity
air
water outlet
inlet (centrates)
struvite extraction
washing
drying
packaging
NaOH
MgCl2
water recirculation

7. The bio-P circle for P-recovery
Better conditions for bio-P process
Chemical precipitation
Me:P <1
Include Bio-P
Using process control
More P-release from digester sludge
Higher internal P-load
-> but recovered!
Lower chemical bound P-content in sludge
40% of P in fertilizer
55% of P in sludge

8. Improved results: 45% recovery –, Aarhus case - feasible
Pct. of inlet total-P
FeCl3
inlet
100
115
outlet 4
WWTP 4%
10-20
111
SSH
bio-sludge
Digester
Magnesium 93
15-22
reject
33-43
sludge
50-60
P-recovery
Decanter
51%
35-45
45% 8

9. Quality of struvite and sludge, Aarhus plant
3 samples
Land application in DK. DM %
23,7 N
% of DM
5,4 P
3,22
% of sample
5,8
12,3 Mg
10,3 Cd
mg/kg
0,9
<0,02
0.8 Hg
0,5
<0,1 Pb 23
<0,2
120 Ni
24,4
0,3 30 Cr
17,1
100 Zn
580
2,7
4000 Cu
230
0,7
1000
mg/kgP 28
<0,16 16
<0,8
200
714
<1,67
10000
758
2500
no heavy metals!

10. Financial Sustainability of P recovery Value creation (Herning case)
Cost
Unit
Value
Electricity
Euro/year
6 100
MgCl2 ”
50 700
NaOH
6 700
O&M
12 100
Total costs to operate
75 600
Savings
Ferric chloride (P removal)
53 300
Polymer(sludge dewatering)
2 000
Electricity (less nitrification)
3 900
Sludge disposal (less volume)
16 000
Biogas (more production)
5 600
Less struvit fighting (O&M costs)
20 700
Total Saving for WWTP
Income
Sales of struvit/ MAP (350€/t)
49 100
Financial balance at 45 % P recovery (in €/y)
Operational costs are approx.:
Savings are calculated/estimated to:
Income from sales of struvite is:
The resulting net income is
Return of investment?
The investment cost (as sales price) for the P recovery plant was €
ROI of approx. 6.2 years when operating on both sources of reject waters, and reaching 45 % total P recovery
With ROI approx. 7 years - P recovery is a sustainable investment for many water utilities

11. Front view of reactors and plant

12. Drying of struvite product, test plant Åby

13. Silo and bagging of final product

14. Phosphogreen™ Summary Advantages of investment
Innovative & effective reject water treatment solution
Overall OPEX Cost advantage
“Green Image”  phosphorus recovery and reuse
ROI ~7 years depending on plant
Value creation
No or very reduced scaling problems
Reduced chemical use for chemical P removal
Reduced costs for sludge dewatering
Reduced energy uptake for nitrification
Less sludge produced
A fertilizer with high value: Struvite
Residual sludge with better N:P balance
The product is approx. 2 mm pellets ready for use as fertilizer
P=12,5%
N=5,5%
Mg= 10%

15. Case for Phosphogreen™ Marselisborg WWTP Reject water treatment project ( PE) Largest P-recovery plant in Scandinavia

16. Marselisborg WWTP – New building

17. Existing technology – ready to use fertilizer

18. Vi ses ved speed-dating 
Suez Water A/S
Rugaardsvej 5, 8680 Ry, Denmark Tel:
Mobile/Direct: mail;
Phosphorgreen™