Upload
others
View
3
Download
0
Embed Size (px)
Citation preview
Van Den Hende S.1, Beelen V. 1, Bore G. 1, Boon N. 2, Vervaeren H. 1 1 Lab of Industrial Water and Ecotechnology (LIWET), Ghent University, Belgium 2 Lab of Microbial Ecology and Technology (LabMET), Ghent University , Belgium Aquaculture Europe 2014, 17th October
Adding value to pike perch culture wastewater via microalgal bacterial flocs: From concept to outdoor scale
http://www.west-vlaanderen.be/http://www.ugent.be/http://www.kbs-frb.be/index.aspx
Bacteria
Wastewater COD, N, P
O2
CO2
Microalgae
Photosynthetic aeration CO2 scavenging Solar energy into biomass Nutrient recovery
Bacteria
Wastewater COD, N, P
O2
CO2, N2
CO2, N2
O2
Algal bacterial system
Nutrient removal Nitrification/denitrification Mechanical aeration up to 50 % of working costs
Discharge norms for effluent
Conventional system
Needed: redesign of wastewater treatment
Bacteria
Wastewater COD, N, P
O2
CO2
Microalgae
Photosynthetic aeration CO2 scavenging Solar energy into biomass Nutrient recovery
Bacteria
Wastewater COD, N, P
O2
CO2, N2
CO2, N2
O2
Algal bacterial system
Discharge norms for effluent
Nutrient removal Nitrification/denitrification Mechanical aeration ~50 % of working costs
Conventional system
Bacteria
Bioresource water COD, N, P
O2
CO2
Microalgae
Nutrient recovery CO2 scavenging Photosynthetic aeration (O2) Solar energy into biomass
Bacteria
Wastewater COD, N, P
O2
CO2, N2
CO2, N2
O2
Microalgal bacterial system Conventional system
Discharge norms for effluent
Nutrient removal Nitrification/denitrification Mechanical aeration ~50 % of working costs
Needed: redesign of wastewater treatment
Problem
Microalgae are difficult to separate from the treated wastewater
Harvesting is expensive: up to 30 % of operational costs
Solution @ Ghent University/Howest
Biomass-free effluent
Bioflocculation of microalgae & bacteria
Microalgal bacterial flocs = MaB-flocs
Settle without flocculant addition
0.1 mm
200 µm
Microalgae Bacteria
Van Den Hende S., 2014. Microalgal bacterial floc for wastewater treatment: from concept to pilot scale.
PhD dissertation, Ghent Univ., 324p. Promotors: Prof. dr. Nico Boon (LabMET), dr. Han Vervaeren (LIWET).
Needed: cheap separation of algae & water
1. Collect a mix of microalgae outdoors
2. Collect wastewater
Wastewater, Alpro Sieve, Alpro Water tank, Alpro
The secret recipe of making MaB-flocs
3. Mix algae and wastewater in sequencing batch reactor (SBR)
Selection of fast-settling flocs in 1-2 weeks
Discharge
treated
wastewater
= effluent
Add
wastewater
= influent
Settling of
MaB-flocs
Stirring of
MaB-flocs
and
wastewater
The secret recipe of making MaB-flocs
Other advantages of the MaB-floc SBR concept
1. Costless separation of treated wastewater and MaB-flocs
MaB-flocs settle at night in the reactor
No additional settling tank for effluent discharge
2. Hydraulic retention time can be decoupled from sludge retention time
Dilution rate ≠ algal growth rate
Possible: treatment of low-strength wastewaters at high algal biomass densities
3. Flocs are large (200-500 µm) and easily harvested
Can be harvested by filter press (200 µm)
No flocculants needed: cost saving, no chemical contamination
Problem: wastewaters strongly differ
Nutrient composition, pH, toxic compounds, ….
Solution: screen various wastewaters
Pike perch culture (Inagro)
Manure treatment (Innova Manure)
Food-processing industry (Alpro)
Chemical industry (BASF)
Van Den Hende et al., 2014b. Treatment of industrial wastewaters by microalgal bacterial flocs in
sequencing batch reactors. Bioresour. Technol. 161, 245-254.
Which wastewaters?
Problem: wastewaters strongly differ
Nutrient composition, pH, toxic compounds, ….
Solution: screen various wastewaters
Pike perch culture (Inagro)
Manure treatment (Innova Manure)
Food-processing industry (Alpro)
Chemical industry (BASF)
Van Den Hende et al., 2014b. Treatment of industrial wastewaters by microalgal bacterial flocs in
sequencing batch reactors. Bioresour. Technol. 161, 245-254.
Which wastewaters?
Best !
Problem:
Lab data should not be extrapolated to outdoor scale with conversion factor of 1
Solution:
Up-scaling to raceway algae pond
Pilot Reactor Network
INTERREG IVB NWE project with 9 pilots
Lab PBR > 100 ton ha-1 y-1
Outdoor ponds ? ton microalgae ha-1 y-1
From lab reactor to open pond
Settling
MaB-floc SBR
Pike perch culture wastewater
Flue gas Dischargeable effluent
Shrimp Shrimp feed Dewatering
4. MaB-flocs as shrimp feed ?
Up-scaling to outdoor pond ? 1. Wastewater treatment 2. Biomass: bioflocculation and harvesting
3. MaB-flocs for biogas ?
Biogas
EnAlgae research questions
Picture: Tim Lacoere, Labmet
Outline
13
1. Wastewater treatment 2. Biomass: bioflocculation & harvesting 3. Biogas 4. Shrimp feed
Wastewater origin
Fish tanks Drum filter (30 µm)
Effluent discharge (10 % / day)
MaB-floc
SBR
Biofilter
Pike perch Sander lucioperca L.
UV O2 Water
Feed
Aquaculture Practice Center (Stefan Teerlinck, Laurens Buyse , Geert Bourgeois)
Sewerage
4 L indoor 40 L indoor Kortrijk (Belgium) Kortrijk (Belgium)
D: 0.350 m
L: 0.351 m
B: 0.325 m
20 L
day-1 20 L
day-1
Upscaling for aquaculture wastewater: reactors
400 L indoor Roeselare (Belgium)
D: 0.356 m
L: 1.170 m
B: 0.960 m
100 L
day-1
100 L day-1
Influent tank MaB-floc SBR Settling tank
Sieve on settling tank
Sludge
Upscaling for aquaculture wastewater: reactors
12 m3 outdoor Roeselare (Belgium) Pilot construction by 2 SMEs: CATAEL bvba, Bebouwen & Bewaren nv
D: 0.4 m
L: 11.7 m
B: 2.5 m
1.5-3 m3
day-1
Influent tank
MaB-floc SBR
Settling tank
1.5-3 m3
day-1
MaB-flocs
Effluent tank
PLC
Heater
CO2
Propeller pump
for SBR stirring
Sludge
pH,T DO
N S
Upscaling for aquaculture wastewater: reactors
Below effluent discharge norms for COD, BOD5, NH4+, TN, TP, PO4
3-
Low PO43- and TP concentrations in effluent (< 0.8 mg P L-1 ; as low as 0.1)
-> potential as P-polishing technology
40 L indoor 400 L indoor 12 m3 outdoor pond
Influent Effluent
Outdoor pond: effluent quality
Photosynthetic aeration by
microalgae was sufficient
Dissolved oxygen production
in line with solar radiation
No mechanical aeration
needed: cost saving
More land area needed !
MaB-floc ponds: 0.4 m deep
CAS : 4 m deep
Time
Outdoor pond: photosynthetic aeration is ok!
Diurnal pH fluctuations
Photosynthesis
increases pH during day
Respiration
decreases pH during night
Effluent discharge
after night to reach pH discharge norm
-> this strategy is not sufficient in summer
0
20
40
60
80
201
3-0
1-2
4
201
3-0
2-2
1
201
3-0
3-2
1
201
3-0
4-1
8
201
3-0
5-1
6
201
3-0
6-1
3
201
3-0
7-1
1
201
3-0
8-0
8
201
3-0
9-0
5
PP
FD
(m
mo
l P
AR
/ L
reacto
r /
SB
R c
ycle
)
Time
1 2 3 4 5 6 7 8
7
8
9
10
11
12
Reacto
r p
H
1 2 3 4 5 6 7 8
Problem 1: pH in outdoor pond
12 m3 raceway pond
Outdoors, flue gas (5% CO2) was needed to lower pH
Flue gas injection = extra cost !
But, low flue gas flow rates: 0.00004 vvm, so low cost
Flue gas injection in open pond ≠ CO2 credits !
MaB-floc SBR is not a flue gas treatment systems -> needed area !
7
8
9
10
11
0 50 100 150 200 250
1 2 3 4 5 6 7 8
No flue gas Time (days)
pH
Norm
Effluent
Influent
Problem 1: pH in outdoor pond
Indoors, nitrite concentration in effluent was not a problem
Outdoors, nitrite was often above the norm for discharge (0.9 mg N-NO2- L-1)
for reuse (1.8 mg N-NO2- L-1)
Solution: avoid nitrite formation in the influent buffer tank?
Discharge
Norm
Influent
Effluent
Time (days) Time (days)
400 L 12 m3 outdoor pond
0
2
4
6
8
0 50 100 150 200 2500
1
2
0 25 50 75 100
N-N
O2- (
mg
/ L
)
Problem 2: nitrite in outdoor pond
1. Photosynthetic aeration was sufficient, even in Belgium
2. Outdoor operation needed flue gas injection
Low loading, but extra cost
3. Effluent quality was ok, but …
Except for nitrite
Land area: 1 m2 MaB-floc pond area per m3 pike perch fish tank 0.05 m2 CAS
Pond heating: needed in winter -> waste heat?
Conclusions: upscaling
Outline
24
1. Wastewater treatment 2. Biomass: bioflocculation & harvesting 3. Biogas 4. Shrimp feed
Up-scaling shifted the dominant algal sp.
Phormidium sp. indoor
(filamentous cyanobacteria)
to Ulothrix or Klebsormidum sp. outdoor
(filamentous microalgae)
400 L indoor
Raceway outdoor
Effect of scale-up on MaB-flocs: species
Up-scaling increased crystal content
Red = chlorophyll -> algae
Blue = crystals
Ash was up to 30% calcium -> CaCO3
Positive for wastewater treatment
Enhance settling of MaB-flocs
Hardness removal
Negative for biomass valorisation?
Decreased energy content of biomass
Reactor scaling
Unbalanced Ca:P:K ratio
400 L indoor
Raceway outdoor
Effect of scale-up on MaB-flocs: crystals
100 µm bars
*Scale-up conversion factor
Scale-up decreased the biomass productivity
Per reactor volume: 10 times less TSS, 13 times less VSS
Average outdoors: 33 ton TSS hapond-1 y-1 or 12 ton VSS hapond
-1 y-1
1.5-4 times lower compared to www-fed HRAP in cold climate (Park et al., 2011)
But, no optimisation yet!
Increased presence of predators
Tubifex sp. can increase palatability and appetites of fish (Lietz, 1988)
Reactor Productivity
(mg TSS
Lreactor day-1)
Productivity
(mg VSS
Lreactor day-1)
4 L indoor 236 ± 73 (10)* 109 ± 30 (13)
40 L indoor 65 ± 8 (2.9) 45 ± 6 (5.5)
400 L indoor 16 ± 23 (0.6) 12 ± 17 (1.3)
12 m3 outdoor 23 ± 54 (1.0) 8 ± 18 (1.0)
Effect of scale-up on MaB-flocs: productivity
MaB-floc SBR pilot
2.1. Filtering by gravity
2.2. Filtering by hydropress
1. Settling of MaB-flocs (1 hour)
MaB-floc cake
MaB-floc harvesting: 1. settling, 2. filtering
MaB-flocs
In pond Settled MaB-floc slurry 70 g TSS L-1
MaB-floc cake: 43 ± 8 % dry matter
1. Concentrating step: settling
2. Dewatering step: filtering 150-250 µm
Supernatant:
7.9 ± 5.7 % MaB-floc TSS loss, pumped back into pond -> No loss!
Gravity filtrate:
1.2 ± 0.9 % MaB-floc TSS loss
2.1. Gravity filtering
2.2. Hydropress filtering
Press filtrate:
0.05 ± 0.03 % MaB-floc TSS loss
MaB-floc harvesting: 98% biomass recovery
As for dominant algal species, lab results can not be extrapolated
Importance of outdoor pilot tests !
Upscaling improved settling of MaB-flocs !
Proof-of-principle that bioflocculation outdoors in NWE can be successful
Moderate biomass productivity
Should only be improved if a lucrative valorisation pathway is found
Very efficient dewatering with filter press at large pore size (200 µm) !!
Water powered filter press: 0.16 € kg-1 DM MaB-flocs (4 bar water)
Electricity powered filter press: 0.04-0.07 kWhel kg-1 DM (Udom et al., 2013)
-> Dewatering: < 0.01 € kg-1 DM MaB-flocs !
Van Den Hende et al., 2014a. Up-scaling aquaculture treatment microalgal bacterial flocs in sequencing
batch reactors: From lab reactors to an outdoor raceway pond. Bioresour. Technol. 159, 342-354.
Conclusions: biomass
Outline
31
1. Wastewater treatment 2. Biomass: bioflocculation & harvesting 3. Biogas 4. Shrimp feed
Biomethane potential (BMP) of MaB-flocs
MaB-flocs from pilot: July - September 2013
Moderate MaB-floc BMP ~ activated sludge BMP
145-205 NL CH4 kg-1
MaB-flocs VS and 67 % CH4 in biogas
143-587 NL CH4 kg-1
algae VS (Ward et al., 2014)
Low anaerobic digestion efficiency
ƞAD 27 - 34 %
Only 51-65 % of chlorophyll was removed during AD batch
Needed: pretreatment of MaB-flocs
Biogas resource: MaB-flocs?
Only positive effect on BMP was microwave treatment (870 s, 700W)
9.4 ± 5.4 % increase of BMP with 2.3 MJ kg-1 MaB-floc TS
Compared to 27 % increase of BMP with > 20 MJ kg-1 TS (Passos et al., 2013)
-> Energetically not interesting
0 50 100 150 200
Control
Freeze/thaw
Autoclave
Microwave
Chlor. + sonication
BMP (NL CH4 kg-1 VS)
0 20 40
ƞ AD (%)
Biogas resource: pretreated MaB-flocs?
AD to biogas seems not economical interesting for these MaB-flocs
2500 Nm-3 CH4 hapond area-1
y-1 (= half of 1 ha of corn)
Biogas low price: 0.30 € kg-1 MaB-floc VS or < 0.01 € m-3 wastewater
Low compared to wastewater treatment cost of 0.30-0.60 € m-3 (Verstraete et al., 2009)
Practical constraints
Scaling (CaCO3) of reactors due to high ash content of MaB-flocs
Needed: biomass valorisation pathways with €
If MaB-floc market price of 2.5 € kg-1 DM -> 0.32 € m-3 wastewater
Conclusions: biogas
Outline
35
1. Wastewater treatment 2. Biomass: bioflocculation & harvesting 3. Biogas 4. Shrimp feed
Research question:
Can MaB-flocs be included in diets of white Pacific shrimp?
Litopenaeus vannamei (Boone 1931)
0 - 2 - 4 - 6 - 8 % inclusion
Mainly wheat was replaced
1. Shrimp quantity?
2. Shrimp quality?
Problem:
What to do with these low-energy MaB-flocs ?
Compound Content (%)
Ash 62
Calcium 17
Protein 21
Lipid 4
Need and research question
0-2-4-6-8 % MaB-floc inclusion did NOT lead to significant difference of
Shrimp quantity Range of averages of all trials
Survival 93 - 97 %
Weight gain 0.32 - 0.34 g day-1
Feed conversion ratio 1.17 - 1.27
Shrimp quality
Proximate composition
Fatty acid profile
Shrimp production: no effect of diets
0
5
10
15
20
25
30
a b L
Re
fle
cta
nce
of
red
ness,
yello
wn
ess o
f co
oked
sh
rim
p
0% MaB 2% MaB 4% MaB 6% MaB 8% MaB
d
dc cb
ba a
b b b
a
a
b a ba ba b
Redness Yellowness
MaB-flocs effect pigmentation of
cooked shrimp tails
Enhanced redness and yellowness
MaB-flocs contain 0.25 % carotenoids
Increased market value of shrimp ?
Shrimp colour: significant effect of diets
Regulation EC No 767/2009: NO!
Restricts the use of waste from treatment of industrial wastewater in animal feed
Directive 91/271/EEC: BUT…
Industrial wastewater is ‘wastewater which is discharged’
e. g. aquaculture wastewater in closed RAS = process water ?
Regulation EC No 767/2009: BUT…
Restricts the use of faeces and urine including of fish (aquaculture) in feed that
enters the EU market
Opportunities: YES?
1. Don’t bring it on the market -> use it where it is produced -> integrated system
2. Food company process water = bioresource water
MaB-floc pilot operation in 2014 by Ghent University at food company Alpro
EU feed market regulations: is it legal?
High ash content of MaB-flocs from pikeperch wastewater treatment
Low inclusion of MaB-flocs enhance pigmentation
Increased inclusion of MaB-flocs in diets: 0-50 %?
Data needed on health and safety (biotoxins, heavy metals, pathogens, etc…)
Replace more expensive ingredients of > 300 € ton-1
Dewatering, drying and grinding of MaB-flocs: 200-300 € ton-1 MaB-floc DM
Wheat ~200 € ton-1
Region specific applications
NWE Europe: process water which does not contain manure particles
Tropical regions with large shrimp industry?
Van Den Hende et al., 2014c. Microalgal bacterial flocs originating from aquaculture wastewater treatment as diet ingredient for Litopenaeus vannamei (Boone). Aquacult. Res., DOI: 10.1111/are.12564.
Conclusions: shrimp feed
Settling of MaB-flocs
MaB-floc SBR
Wastewater
Flue gas Dischargeable
effluent
Dewatering of MaB-flocs
5. Fertilizer for tomatoes (J. Coppens, UGent)
4. Outdoor pilot at food industry
Shrimp Biogas Fertilizer
1. Economics (E. Vulsteke, UGent)
2. LCA (S. Sfez, UGent)
3. Growth modelling (Swansea University)
MaB-floc pilot: current research
http://www.google.be/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&uact=8&docid=WeC_Sv_kN64v4M&tbnid=SVefG2gibFPTPM:&ved=0CAcQjRw&url=http://www.alpro.com/corporate/en/powerful-stories-about-plants/things-we-do-to-sustain-the-planet&ei=l6wYVL3dKIiXaoutgNgK&bvm=bv.75097201,d.d2s&psig=AFQjCNGCxzHLevONQz_tx2OjnO35w454LA&ust=1410989561481683
Valorisation of MaB-floc biomass of Alpro
Proof-of-principle in an tropical aquaculture area Availability: light, heat, wastewater,
experience in algae and ponds,
large aquaculture industry
Need for: wastewater treatment and
aquaculture feed ingredients
Future research: interested in collaboration?
Size matters.
Micro-algae
MaB-floc
Size matters.
Size matters.
Sofie.VanDenHende @ugent.be Presentation on: www.enalgae.eu
Thank you ! Looking forward to a future MaB-floc collaboration !
http://www.enalgae.eu/