stripper tilburg

© Colsen Group 2012
www.colsen.eu
www.colsen.eu
Colsen International b.v.




Kreekzoom 5, 4561, GX Hulst, NL
+31 (0)114 – 31 15 48
+31 (0)114 – 31 60 11
info@colsen.eu
© Colsen Group 2012
Table of contents
PART II:
The Energy F actory
1. Motive for development
PART I: Colsen
2. Thermophilic sludge digestion
1. About Colsen
3. Optimizing energy production
2. Services and technologies
4. Nutrient recovery
5. Latest developments
www.colsen.eu
Page 3 / 52
I.1. About Colsen
Consultancy
Colsen LATAM - Argentina
Technology
Colsen Ecopreneur - Chili
Bachirat Colsen - Morocco
Engineering
Ahidra Colsen - Spain
Colsen Milieu - Belgium
Italia - HydroItalia Colsen
Romania - Colsen - van den Hul VOF
Colsen
Consultancy
Colsen b.v. - The Netherlands
www.colsen.eu
Technology
Engineering
Global
partners
Page 4 / 52
I.2. Services & technologies
Organic pollutants removal
N/P removal & recovery
Municipal wastewater
treatment plant
Technologies
Biogas cleaning
Industrial wastewater
treatment plant
Services
Post-purification (polishing) /
water reuse
Agricultural biogas plants
Industrial biogas plants
www.colsen.eu
Page 5 / 52
I.2. Services & technologies
Thermophilic digestion
www.colsen.eu
Page 6 / 52
I.2. Services & technologies
Waste water treatment
www.colsen.eu
Page 7 / 52
I.2. Services & technologies
Digestate treatment
www.colsen.eu
Page 8 / 52
I.2. Services & technologies
UASB
www.colsen.eu
Page 9 / 52
I.2. Services & technologies
ANPHOS®
www.colsen.eu
Page 10 / 52
I.2. Services & technologies
AMFER®
www.colsen.eu
Page 11 / 52
I.2. Services & technologies
NAS®-MBR
www.colsen.eu
Page 12 / 52
I.2. Services & technologies
Water re-use
www.colsen.eu
Page 13 / 52
Table of contents
PART II:
The Energy F actory
1. Motive for development
PART I: Colsen
2. Thermophilic sludge digestion
1. About Colsen
3. Optimizing energy production
2. Services and technologies
4. Nutrient recovery
5. Latest developments
www.colsen.eu
Page 14 / 52
II.1. Motive for development
The Energy Factory:
Striving towards Electricity producing waste water treatment,
with production of Energy, nutrients and clean water.
>100%
(Lazarova et al., 2012, Water21)
Focus on sludge line:
Energy recovery through thermophilic sludge digestion
Nutrient recovery
www.colsen.eu
Page 15 / 52
II.2. Thermophilic sludge digestion
The Energy Factory:
Striving towards Electricity producing waste water treatment
Valorization to green gas
BIDOX®
η 42%
electrical
Biogas
kW(e) + kW(th)
Drying
CHP
Bio-sulphuric acid
Ammoniumsulphate
WWTP
sewage
sludge
Effluent
to main
stream
STP
Digestion
tank
Separator
Stripper
Anphos®
AMFER®
NAS®-SBR
Dryer
Struvite
Thermophilic sludge digestion
www.colsen.eu
Page 16 / 52
II.2. Thermophilic sludge digestion
Conventional sewage treatment:
 Sludge line:
• 20 kg DM IE-1 year-1 to sludge;
 1.500.000 tons sludge per year
• Sludge treatment and disposal: 40% of STP opex
 average cost € 330 / ton sludge (incl. dewatering and
processing costs)

•
•
•
Traditional (mesophilic ) sludge digestion:
Prim. sludge / sec. sludge = 50 : 50
Hydraulic Retention Time 20 days
Average yield: 25 – 40% odm conversion
www.colsen.eu
Page 17 / 52
II.2. Thermophilic sludge digestion
Sewage treatment of the future:
 Thermophilic sludge digestion:
• Tests indicate 60 – 70% odm conversion
Anticipated results
•
•
•
•
•
•
More biogas produced
Less digested sludge to be processed
Lower operational costs
More nutrients (N/P) in digestate
More H2S in biogas
Lower sludge disposal quantity
www.colsen.eu
Technical need for
• HRT of 18 – 20 days
• Optimal mixing
• Strict temperature control
Page 18 / 52
II.2. Thermophilic sludge digestion
More efficiency at higher process temperatures:
Thermophilic
bacteria
Mesophilic bacteria
•
•
•
•
~90% odm conversion primary sludge
~50% odm conversion secondary sludge
Total reduction (prim. sludge / sec. sludge = 50 : 50)  70% odm
Up to 50% more biogas; more electrical and thermal energy for
use on STP or external
• More nutrients: NH4+-N > 2,500 mg/L; PO43--P > 600 mg/L
• More sulphur in biogas: H2S > 2,000 ppm
www.colsen.eu
Page 19 / 52
II.2. Thermophilic sludge digestion
Example; three Dutch STP’s
Tilburg (A)
STP
Capacity (IE)
Sludge production (kg ODM/IE/year)
(Primary + secondary)
Digester volume (m3)
Digester loading rate (kg ODM/m3/d)
Digester SRT (d)
www.colsen.eu
Land van Cuijk (B)
A
Bath (C)
B
C
375,000
175,000
536,000
16,1
(9,6 + 6,5)
12,4
(0 + 12,4)
10,9
(5,4 + 5,5)
2 x 4440
2900
2 x 5430
1,86
2,05
1,48
20
25
20
Page 20 / 52
II.2. Thermophilic sludge digestion
Thermophilic vs. mesophilic sludge digestion:
Thermophilic sludge digestion:
100 – 150% improvement
Mesophilic
(practice)
Optimal
mesophilic
Thermophilic
A
B
C
Primary sludge
(%ODM conv.)
55
-
50
60
90
Secondary sludge
(%ODM conv.)
25
38
25
35
50
Electrical efficiency
(%)
35
23
30
40
40
Mesophilic sludge digestion:
40– 70% improvement
www.colsen.eu
Page 21 / 52
II.2. Thermophilic sludge digestion
Electricity autarky (self efficiency):
=
STP
Tilburg
(A)
Land van Cuijk
(B)
Bath
(C)
Current mesophilic
60%
18%
38%
Optimized mesophilic
82%
32%
66%
Thermophilic
120%
42%
97%
STPs with primary- and secondary sludge
become energy-neutral or energy producing
after thermophilic sludge digestion
www.colsen.eu
Page 22 / 52
II.2. Thermophilic sludge digestion
Opex savings sludge treatment:
optimized mesophilic and thermophilic digestion vs. current mesophilic digestion
Tilburg
Land van
Cuijk
Bath
Sludge opex saving: 18 – 75% (opt. Mesophilic) v.s. 36 – 123% Thermophilic
Contribution electricity gain: 40 – 60% (opt. Mesophilic) vs. 50 – 70% Thermophilic
www.colsen.eu
Page 23 / 52
II.2. Thermophilic sludge digestion
Thermophilic heat requirement:
STP
Tilburg
(A)
Land van Cuijk
(B)
Bath
(C)
Heat production (kWth)
1150
255
1602
Heat requirement (kWth)
1052
270
1260
98
- 15
342
Excess heat (kWth)
STPs with primary- and secondary sludge: no additional costs involved;
STP with only secondary sludge: negligible cost involved (€ 0,02/IE/year)
www.colsen.eu
Page 24 / 52
II.2. Thermophilic sludge digestion
Business case for STP Bath (C)
Parameter
Current mesophilic
digestion
Thermophilic
digestion
3.480.650
4.692.945
Revenu (€/year)
313.259
422.365
Maintenance costs CHP (€/year)
24.365
32.851
DM production (ton/year)
5.914
4.783
PE use (kg active PE/year)
41.398
33.481
PE costs (€/year)
165.592
133.924
Sludge cake transport off-site (ton/year)
30.414
24.656
2.341.878
1.898.512
2.218.576
1.642.922
-
575.654
Electricity production (kWh)
Costs sludge transport (€/year)
Total costs (€/year)
Savings compared to current (€/year)
www.colsen.eu
Page 25 / 52
II.2. Thermophilic sludge digestion
DIGESTMIX® system
•
•
•
•
•
www.colsen.eu
• ~90%
Optimal
odmmixing
conversion
(promote
primary
sludge
sludge
digestion, avoid foam, scum)
• ~50%
No moving
odm conversion
parts inside
secondary
the digestion
sludgetank
• Total
Accurate
reduction
temperature
(prim. sludge
control
/ sec. sludge = 50 : 50)  70% odm
• More
No extra
nutrients:
heat necessary,
NH4+-N > 2,500
because
mg/L;
thermal
PO43--P
energy
> 600production
mg/L
is
More
higher
sulphur in biogas: H2S > 2,000 ppm
Page 26 / 52
II.2. Thermophilic sludge digestion
Alternative for thermophilic sludge digestion:
 Thermal hydrolysis prior to (mesophilic or thermophilic)
digestion.
• ~90% odm conversion primary sludge
• •~50%
odm mixing
conversion
secondary
Optimal
(promote
sludgesludge
digestion, avoid
foam, scum)
Anticipated
results
Disadvantages
• •Total
reduction
(prim. sludge
/ sec. sludge
= 50 : 50)
70%
Accurate
temperature
control
• Operate
at 6
– 10
barodm
pressure
• Same
results
as
thermophilic
+
3• •More
nutrients:
mg/L;
> 600
mg/L
No extra
heat NH
necessary,
because
thermal
energy
production
4 -N > 2,500
4 -P
• PO
Operate
at 140
– 180°C is
digestion
• More
sulphur in biogas: H2S > 2,000 ppm
higher
• High capex and opex!
www.colsen.eu
Page 27 / 52
II.2. Thermophilic sludge digestion
Thermophilic sludge digestion vs. thermal hydrolysis
www.colsen.eu
Thermophilic
digestion
Thermal
hydrolysis
Capex
-
+++
Opex
-
+++
Revenue
++
++
Overall efficiency
++
-
Page 28 / 52
II.3. Optimizing energy production
Higher BOD removal by AB system
BOD removal
First stage
Conventional
25 – 30 %
Pre-settlingtank
AB system
70 – 80 %
Adsorption sludge
Anticipated results
• Up to 60 % more primary sludge
compared to conventional
• More biogas
• Less surplus sludge
www.colsen.eu
Disadvantages
• Need for other denitrification
then conventional
Page 29 / 52
II.3. Optimizing energy production
Example: STP Tilburg (A)
 Primary sludge conversion: 90%
 Surplus conversion: 50%
Conventional (presetteling tank)
AB system
Primary sludge
(kg ODM/day)
6,056
16,150
ODM conv. (kg ODM/day)
5,451
14,535
Surplus sludge
(kg ODM/day)
6,464
1,847
ODM conv. (kg ODM/day)
3,232
923
Total conv. (kg ODM/day)
8,682
15,459
www.colsen.eu
Page 33 / 52
II.3. Optimizing energy production
Electricity autarky (STP Tilburg (A)):
=
STP
Conventional (presetteling tank)
AB system
Current mesophilic
60%
75%
Optimized mesophilic
82%
95%
Thermophilic
120%
140%
More primary sludge results in better efficiency;
CHP should be suitable to process additional biogas. This may
result in the necessity to increase the capacity (investment)
www.colsen.eu
Page 34 / 52
II.3. Optimizing energy production
Valorization to green gas
BIDOX®
η 42%
electrical
Biogas
kW(e) + kW(th)
Drying
CHP
Bio-sulphuric acid
Ammoniumsulphate
WWTP
sewage
sludge
Effluent
to main
stream
STP
Digestion
tank
Separator
Stripper
Anphos®
AMFER®
NAS®-SBR
Dryer
Struvite
Desulphurizing and drying of biogas
www.colsen.eu
Page 32 / 52
II.3. Optimizing energy production
Biological biogas desulphurization by oxidation (BIDOX®)
BIDOX® system
•
•
•
•
www.colsen.eu
High efficiency H2S removal  less corrosion in CHP
No chemical requirements
Low running costs
No clogging with elemental S; production of bio sulphuric acid
Page 33 / 52
II.3. Optimizing energy production
Biogas drying for better efficiency on CHP
Conditioning of desulphurized biogas before use in CHP
• Higher efficiency on CHP; up to 42% electrical efficiency
• More uptime of the biogas engine
• Lower maintenance costs
www.colsen.eu
Page 34 / 52
II.4. Nutrient recovery
Facilitate the main stream of the STP by Partial flow treatment
 Most Dutch STP’s must meet the following effluent
requirements:
Parameter
Permit
COD
125 mg/L
BOD
20 mg/L
SS
30 mg/L
N-total
10 mg/L
P-Total
2 mg/L
 Treatment of rejection water removes extra nutrient load to
main stream of STP after thermophilic sludge digestion
www.colsen.eu
Page 35 / 52
II.4. Nutrient recovery
Facilitate the main stream of the STP by Partial flow treatment
 After thermophilic digestion considerably more nutrients
(example STP Bath(C)):
Mesophilic
digestion
Thermophilic
digestion
Flow rejection water (m3/day)
473
473
NH4-N concentration (mg/L)
811
1.430
NH4-N load (kg/day)
383
675
PO4-P concentration (mg/L)
80
501
PO4-P load (kg/day)
38
237
292 kg/day extra NH4-N to main stream
199 kg /day extra PO4-P to main stream
 Necessity for partial flow treatment?
www.colsen.eu
Page 36 / 52
II.4. Nutrient recovery
Facilitate the main stream of the STP by Partial flow treatment
Valorization to green gas
BIDOX®
η 42%
electrical
Biogas
kW(e) + kW(th)
Drying
CHP
Bio-sulphuric acid
Ammoniumsulphate
WWTP
sewage
sludge
Effluent
to main
stream
STP
Digestion
tank
Separator
Stripper
Anphos®
AMFER®
NAS®-SBR
Dryer
Struvite
Recovery of Nitrogen
www.colsen.eu
Page 37 / 52
II.4. Nutrient recovery
Recovery of Nitrogen (AMFER®)

•
•
•
•
C2C Nitrogen removal with new air stripping process:
Heating to 60°C
NH4+-N stripping from 2,500 to 500 mg/L (80% N-removal)
Fixation of N as ammonium sulphate; 45% (NH4)2SO4 sol.
Liquid fertilizer; market value € 110/m3
www.colsen.eu
Page 38 / 52
II.4. Nutrient recovery
Recovery of Nitrogen (AMFER®)
 Costs (Example STP Tilburg (A)):
Stripping
AMFER®
Partial nitritation/
Anammox
Removal (kg N/day)
410
757
Opex (€/kg N)
1,8
0,7
Total costs (€/IE/year)
0,19
0,36
www.colsen.eu
Page 39 / 52
II.4. Nutrient recovery
Facilitate the main stream of the STP by Partial flow treatment
Valorization to green gas
BIDOX®
η 42%
electrical
Biogas
kW(e) + kW(th)
Drying
CHP
Bio-sulphuric acid
Ammoniumsulphate
WWTP
sewage
sludge
Effluent
to main
stream
STP
Digestion
tank
Separator
Stripper
Anphos®
AMFER®
NAS®-SBR
Dryer
Struvite
Recovery of Phosphorous
www.colsen.eu
Page 40 / 52
II.4. Nutrient recovery
Recovery of Phosphorous (ANPHOS®)

•
•
•
•
•
C2C Phosphorous removal as struvite:
pH increase by air stripping (not necessary after AMFER®)
Magnesium salt addition
PO43--P removal from 600 to 10 mg/L (> 90% P-removal)
Crystallization and settling; simple dewatering to 40% dm
Slow release fertilizer; market value € 35/ton
www.colsen.eu
Page 41 / 52
II.4. Nutrient recovery
Facilitate the main stream of the STP by Partial flow treatment
Valorization to green gas
BIDOX®
η 42%
electrical
Biogas
kW(e) + kW(th)
Drying
CHP
Bio-sulphuric acid
Ammoniumsulphate
WWTP
sewage
sludge
Effluent
to main
stream
STP
Digestion
tank
Separator
Stripper
Anphos®
AMFER®
NAS®-SBR
Dryer
Struvite
Efficient removal of Nitrogen
www.colsen.eu
Page 42 / 52
II.4. Nutrient removal
NAS® (Hybrid activated sludge / anammox)

•
•
•
•

Efficient removal of Nitrogen:
Biomass consists of up to 10% anammox
Removes > 70% of all N in the anammox stage
Overall removal of nitrogen ~95% (liberated as N2)
Effluent quality: < 20 mg/L N-total
Anammox operate via a shortcut in the nitrogen cycle:
www.colsen.eu
Page 43 / 52
II.4. Nutrient removal
Idea (Anno 2000): use of short-circuit in denitrification reaction
Solution: NAS®
(New Activated Sludge)
NAS 1
NAS 2
NAS 3
Settler
Implementation of pre-nitritation reactor (NAS 1):
•
•
Only 50 % NO2- formation or too much conversion towards NO3Too much COD removal (40 – 50 %) for denitrification
Effluent NAS 1 perfectly suited for Anammox-bacteria (recently discovered)
•
•
www.colsen.eu
Can remove N without COD source
Need combination NH4+ and NO2-
Page 44 / 52
II.4. Nutrient removal
NAS®
NAS 2
NAS 1
NAS 3
Settler
NAS 2
NAS 1
• Proper NH4:NO2 ratio
• Low SRT
• Low DO
• N-removal by anammox
• Saving on O2 consumption (and energy)
• No COD requirement (less sludge growth)
• Conventional denitrification (polishing)
• Effluent lower COD:N
• Saving on O2 consumption (and
energy)
www.colsen.eu
NAS 3
• Polishing effluent
• Complete COD removal
• Complete nitrification
Page 45 / 52
II.4. Nutrient removal
NAS® in industrial waste water treatment already in full-scale for years
NAS® system since 2004
N2 rising bubbles NAS 2
•
Anaerobic treatment (UASB), followed by ANPHOS®
•
NAS 1 – NAS 2 – NAS 3 - Clarifier
•
COD:N ratio of NAS® is 3:1
•
•
•
www.colsen.nl
COD
NH4+
700 – 1000 mg/L
200 - 300 mg/L
Process controlled based on DO and SRT
Page 46 / 52
II.4. Nutrient removal
NAS®: second reactor at LWM Bergen-op-Zoom
• Anaerobic treatment (UASB), followed by ANPHOS®
• Four tanks (NAS 1, NAS 2a, NAS 2b, NAS 3) + settler
• Process controlled based on DO and SRT
• COD:N ratio of NAS® is 3:1
www.colsen.nl
- COD
700 – 1000 mg/L
- NH4+
200 - 300 mg/L
Page 47 / 52
II.4. Nutrient removal
NAS®: second reactor at LWM Bergen-op-Zoom
Experiences:
•
When bypass towards NAS 2 was stopped, stable operation!
(after 1 year)
•
Effluent quality < 10 mg/l N-total
•
Water reuse project with MBR-RO:
•
•
Long term measurements by Ugent (LabMET)
3% of total biomass is Anammox, responsible for ~77% N-total removal
(article published in Water Research)
•
Optimisation of NOB repressing measures
www.colsen.nl
Page 48 / 52
II.4. Nutrient removal
NAS®-MBR: Treating waste water and liquid fraction of digestate
• Thermophilic digester, separation of digestate, UASB followed by ANPHOS®
• Three tanks (NAS 1, NAS 2, NAS 3) + MBR
• Process controlled by DO and SRT
• COD:N of influent NAS is 4
•
•
www.colsen.nl
COD
NH4+
2500 mg/L
600 mg/L
Page 49 / 52
II.4. Nutrient removal
NAS®-MBR: Treating waste water and liquid fraction of digestate
•
Operational since 1 year
•
Effluent quality < 40 mg/L N total
•
Problems with stable operation of NAS 1
•
•
•
High SS in influent (> 3 g/L) due to digester
More N in influent (due to digester)
Solution: extra monitoring needed for process control of NAS 1 (at these conditions)
NAS®-MBR
• Guarantee of SS-free effluent
• NAS® at higher VSS (=smaller footprint)
• Ideal pre-treatment for RO (water re-use)
www.colsen.nl
Page 50 / 52
II.5. Latest developments partial flow treatment
NAS®; as partial flow treatment
executed as Sequencing Batch Reactor (SBR)
SBR-NAS®
• One stage N-removal
• COD:N ratio < 3
• Cases where COD removal is not required
www.colsen.eu
Page 51 / 52
II.5. Latest developments main stream
UNAS®
• N-removal in main stream of sewage treatment
• B-stage in a two stage sewage treatment
as energy factory
www.colsen.nl
Page 52 / 52
II.5. Latest developments main stream
UNAS® (mainstream)
• Low temperature: operational capability for STP
mainstream;
• Granular sludge: no settlingtank but easy
separation by hydrocylone;
• Less aeration because of N-shortcut into
denitrification process
www.colsen.nl
Page 53 / 52
II.5. Latest developments main stream
Profits of AB-system with UNAS® v.s. AB-system*
Aeration
3.970.000
Saving
kWh/y
Pumpenergy
1.250.000
Saving
kWh/y
Thermophile
digestion
4.320.000
Extra
kWhe/y
Total savings
9.540.000
kWh/y
*STP: 75.000 m3/d, 40.000 kg CZV/d, 3.500 kg N-kj/d
www.colsen.nl
Page 54 / 52
www.colsen.eu
Colsen International b.v.




Kreekzoom 5, 4561, GX Hulst, NL
+31 (0)114 – 31 15 48
+31 (0)114 – 31 60 11
info@colsen.nl
© Colsen Group 2012
www.colsen.eu
Colsen International b.v.




Kreekzoom 5, 4561, GX Hulst, NL
+31 (0)114 – 31 15 48
+31 (0)114 – 31 60 11
info@colsen.nl
© Colsen Group 2012