1. DEMON Sustainable Nitrogen Removal with Deammonification
HenkWim de Mooij 1 1

2. DEMON: stable and sustainable N-removal
Developed at Innsbruck University, Austria
Full scale experience since 2003 at Strass WWTP
Nine full scale installations in operation in Europe, six under construction (mostly references on liquors from municipal sewage sludge)
Technology under license from University of Innsbruck (Dr. Bernhard Wett)

3. Side stream treatment implemented
Primary sedimentation
Final clarifier
Activated sludge
influent
effluent
Digester
Dewatering
Liquor Treatment
Sludge
Return Liquors 3 3

4. Nitrogen Cycle Reduced Organic N-components N-Assimilation
(plants, micro-organisms
Microbial
degradation
N-fixation
N-Assimilation
(plants, micro-organisms
Denitrification
NO3-
NO2- N2
NH3
N2O
DEMON
Nitrification
(Nitrobacter)
Nitritation
(Nitrosomonas)
SHARON
NO2- 4

5. Traditional biological nitrogen removal
1 mol NO3-
C-source → sludge
CO2 → sludge O2
1 mol NO2-
1 mol NO2-
CO2 → sludge
C-source → sludge O2
1 mol NH4+
0.5 mol N2

6. DEMON nitrogen removal: deammonification
1 mol NO3-
1.25 NH O2  1.25 NO2-
NH NO2-  N NO H2O
2.25 NH4+
Aerated period
Anoxic period
C-source → sludge
CO2 → sludge O2
0,5 mol NO2-
1 mol NO2-
CO2 → sludge
C-source → sludge
CO2 → sludge
0,5 O2
1 mol NH4+
0.5 mol N mol NO3

7. How does it work? 7

8. DEMON characteristics
Standard SBR configuration
Low energy requirement, as only 55% of ammonia is oxidised to nitrite;
No requirement for an external source of carbon (such as methanol);
Low sludge production;
Stable process due to pH control, process adjusts to changes in flow and load automatically;
No sensitivity to phosphate in sludge liquors, no pre-treatment required.

9. DEMON Control Control aeration Sufficient oxygen for nitrification
Oxygen level limiting for Nitrite oxidizing bact.
0.3 mg/l O2
Control nitrification process
Produce nitrite for deammonification process
Avoid inhibition due to excess nitrite
pH control
Control sludge age
Sufficiently long for anammox to grow (>20 days)
Too short for NOB to grow
Cyclone

10. pH Control of nitrification
- Oxygen
- pH

11. Using pH for nitrite control
- Oxygen
- Nitrite

12. Cyclone for sludge age control
Surplus sludge discharge (NOB)
Surplus sludge
Sludge return
to reactor
(anammox bacteria)

13. DEMON references (operational)
Location
Year
Capacity
Liquor source
Heidelberg, D
2008
480 m³/d, 600 kg/day NH4-N
Mesophilic digested sludge
Thun, CH
300 m³/d, 400 kg/day NH4-N
Glanerland, CH
2007
250 m³/d, 250 kg/day NH4-N
Strass, A
2004
250 m³/d, 500 kg/day NH4-N
Plettenberg, D
100 m³/d, 80 kg/day NH4-N
Limmattal, CH
2010
Etappi Oy, Fi
2009
330 m³/d, 990 kg/day NH4-N
Biogas production
Balingen, D
400 m³/d, 192 kg/day NH4-N
Zalaegerszeg, Hu
160 m³/d, 160 kg/day NH4-N
Gengenbach, D
50 m³/d, 50 kg/day NH4-N
Apeldoorn, NL
1270 m³/d, 1690 kg/day NH4-N

14. DEMON references (under construction)
Location
Year
Capacity
Liquor source
Kecskemet, Tu
1300 kg/day NH4-N
Mesophilic digested sludge
Kokkola, Fi
600 kg/day NH4-N
Lahr, D
235 kg/day NH4-N
Erpfendorf, D
120 kg/day NH4-N
Alltech, D
2400 kg/day NH4-N
Biogas/yeast
Rickenbach, D
50 kg/day NH4-N
Dairy
Nieuwegein, NL
450 kg/day NH4-N
Amersfoort, NL

15. Apeldoorn Sludge Treatment
DEMON LTP
Digesters
CHP

16. DEMON Nieuwegein

17. Design Basis DEMON Nieuwegein
Parameter
Unit
Average
Max
Peak
Flow
m3/d
258
420
480
NH4-N
mg/l
1.059
1.012
kg/d
273
425
486

18. Batch proces DEMON No. of cycles per day : 4 Cycle volume 120
m³/cycle (peak)
Cycle time 6 h
Fill + Aerate phase
4,5
Settlement phase
0,75
Discharge phase

19. DEMON reactor Process Flow Diagram
Cyclone
Surplus sludge
DEMON effluent
Filtrate Break Tank
Filtrate Buffer Tank
G.A. Drawing

20. DEMON reactor Nieuwegein WWtP

21. Buffer tank in reactor

22. Aerated / Anoxic zone in reactor

23. DEMON Cyclone

24. Comparison DEMON / SHARON
Aspect
DEMON
SHARON
Note
Temperature
30 oC
35 oC
Denitrification produces heat
Design basis
Sludge loading, age
HRT 2,25 days
Effect of BOD and TSS on reactor size DEMON
Activated Sludge
SRT >> HRT
SRT = HRT
Simple process
MLSS control
Yes No
Sensitivity to TSS and BOD
NH4 removal
85-90%
95-98%
pH control
(NaOH)
MeOH (NaOH)
MeOH EUR 0,35
per kg NH4 removed
Influent BOD/TSS
Critical
Beneficial
Critical parameters
O2, sludge age, TSS, BOD
HRTox
Operator attention
Process eng.
Passive 24

25. Thank you for your attention
ANY QUESTIONS? 25