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TRANSCRIPT
4/4/2014
1
High Rate Renewable Energy
Production with the Static
Granular Bed Reactor (SGBR)
Tim Ellis, Ph.D., P.E., Associate Professor
Dept. of Civil, Constr. & Environ. Eng.
Iowa State University
Ames, IA 50011
[email protected], 515-294-8922
Introduction
Short overview of anaerobic digestion
Definition of high rate systems
Developments at Iowa State
University
Case studies
Anaerobic Treatment
Historically, anaerobic organisms
Slow growers
unstable (failed systems led to “stuck
digesters”)
Anaerobic treatment is a net energy
producer
Potential to produce equiv. 50,000 bpd
Save 20,000 bpd in aeration costs
Anaerobic yield is ~20% of aerobic
yield
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Anaerobic Digestion in Developing Countries
Community Biogas Plant, China
Biogas Cookstove
Renewable Energy at
Treatment Plants
Low vs. High Rate Waste
Treatment
Modern wastewater treatment plants
have been using high rate (low F:M)
systems for over 100 years for aerobic
treatment
For anaerobic treatment which produces
energy, we’ve been using low rate (high
F:M) systems
◦ Few alternatives to conventional AD
◦ Conventional AD requires long
detention times, heating, mixing
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High Rate Anaerobic Systems
Separate solids retention time (SRT) from hydraulic retention time (HRT). ◦ SRT = mass of solids in system (g) / daily rate of solids
wasted (g/day)
◦ HRT = Volume of Reactor / Flow rate
Can achieve much high organic loads due to retention of biomass.
Higher organic loads makes more economical design due to smaller reactor.
High Rate (low F:M)
Digestion
In 1980’s Lettinga - UASB reactor
Upflow process washed out flocs
Led to anaerobic granule development
Detention times of 1 day or less.
Requires a low solids wastewater
Requires recirculation pumping, and gas solids liquid separator
Typically requires heating to 35ºC to operate satisfactorily
influent
recirculation
pump
baffles
granular
sludge
gas
bubbles
three
phase
separator
biogas
flocculent
sludge
distribution
baffle
effluent
weir
effluent
UASB
granule gas bubble
floc particle
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Anaerobic granules
Current Research and
Development at Iowa State
University
New high rate system
Maximize biomass density (low F:M)
Minimize effluent solids
Meet NPDES permit requirements for
surface water discharge in some
instances
Maximize potential to generate
renewable energy in the form of
biogas
SGBR Defined
High-rate, downflow
anaerobic reactor
Biomass=Anaerobic
granules (seeded from
existing reactors
containing granules)
Submerged Biomass
Gas filled headspace
Gravel underdrain
influent
gravel
underdrain
granule
bed
water level
effluent
biogas
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SGBR vs UASB
0 4 8 12 16 20Organic Loading Rate, g/(L•d)
50
60
70
80
90
100
CO
D R
em
ov
al, %
UASB (Jeison & Chamy)
EGSB (Jeison & Chamy)
UASB (Yan & Tay)
UASB (Fang and Chui)
UASB (Zoutberg & Eker)
UASB (Ramasamy et. al.)
UASB (Jhung & Choi)
AFF (Jhung & Choi)
UASB (This study)
SGBR (This study)
SGBR
UASB
Organic Loading Rate, kg/m3 d
CO
D R
em
ova
l E
ffic
ien
cy,
%
0 2 4 6 8 10 12OLR, kg COD m-3 d-1
20
30
40
50
60
70
80
90
100
CO
D R
em
ova
l, %
This Study
EGSB (Núñez & Martínez)
25 C ASBR (Massé & Masse)
UASB (Ruiz et al.)
AF (Ruiz et al.)
Comparison with other systems
(slaughterhouse wastewater)
SGBR achieved
greater COD
removal than
other systems
Short Start-up Time
(Pork Slaughterhouse in Iowa)
0
20
40
60
80
100
0 5 10 15 20 25 30
Time (Days)
Rem
oval
eff
iency
(%
) .
TSS COD
REACTOR STARTUP
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0
1000
2000
3000
4000
5000
6000
7000T
SS
co
nce
ntr
atio
n (
mg
/L)
.
0
20
40
60
80
100
Rem
ov
al e
ffie
ncy
(%
) .
InfluentEffluentRemoval
0
3000
6000
9000
12000
15000
0 50 100 150 200 250
Time (Days)
CO
D c
on
cen
trat
ion
(m
g/L
) .
0
20
40
60
80
100
Rem
ov
al e
ffie
ncy
(%
) .
InfluentEffluentRemoval
SG
BR
Results –
Pork
Sla
ughte
rhouse
SGBR Results – Landfill leachate
0
20
40
60
80
100
0 2 4 6 8 10 12 14 16 18 20
OLR, kg/m3.d
CO
D R
em.,
%
This Study
Berrueta et al.
Lin et al.
SGBR
Tulare, CA
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Existing Lagoon 7-d detention time, poor performance periodically
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Tulare, CA Operating Results
Backwashing Efficiency
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Summary
Simple, effective and economical method to
treat a wide variety of municipal, industrial, and
agricultural waste streams and produce a
renewable source of energy
Recirculation pumping, mixing, baffling, heating
not required with SGBR
Stability of system ensured by its ability to retain
active biomass (measured SRTs from 8 to 20
years!)
Hydraulic detention times typically 12 – 24
hours
Questions?