thermal hydrolysis for biosolids stabilization
TRANSCRIPT
Neptune workshop: Technical Solutions for Nutrient and Micropollutants Removal in WWTPs
Université Laval, Québec, March 25-26, 2010
Thermal hydrolysis for
biosolids stabilization
Pretreatment for Anaerobic Digestion
Damien Batstone
Advanced Water Management Centre, The University of Queensland
Neptune Workshop, Université Laval, Québec, March 25-26, 2010
Sludge Steams from WWT
Aeration Basin Clarifier
Influent
Return activated sludge
Effl.
Waste sludge
Digester 40-50% removal
gas
Primary sludge
Thickener
Neptune Workshop, Université Laval, Québec, March 25-26, 2010
The Scale of Biosolids/Sludge
• People produce 50 g dry (400g wet) biosolids per
day each
• In Australia, 5 million wet tonnes per day
• Equivalent to 150,000x40 tonne trucks
• Costs $50-$100 per wet tonne
• 30%-60% of overall wastewater treatment plant
costs
• 1M people produce enough “energy” to power
10,000 homes (2% of energy demand)
And that’s only from people! What about
everything else??
Neptune Workshop, Université Laval, Québec, March 25-26, 2010
Emerging trends with BNR
Aeration Basin Clarifier
Influent
Return activated sludge
Effl.
Waste sludge
Digester 40-50% removal
gas
Primary sludge
Thickener
0%
10%
20%
30%
40%
50%
60%
5 10 15 20 25 30 35 40
Activated Sludge Age (d)
Deg
rad
ab
ilit
y (
%)
Long Sludge Age = Low
Degradability!
Neptune Workshop, Université Laval, Québec, March 25-26, 2010
Key Outcome 1 – Neptune
Thermal hydrolysis is cost neutral but
greenhouse negative. Costs are shifted to
capital expense instead of operating
expense.
Batstone, DJ, Keller, J., and Darvodelsky, P.S. (2008) “Trends in Biosolids Handling
Technologies: Economics and Environmental Factors” AWA Biosolids Conference June 7-10,
Adelaide.
Neptune Workshop, Université Laval, Québec, March 25-26, 2010
-0.5 0 0.5 1 1.5 2 2.5 3
Landfill
Current Combined
Decentralised Aerobic
Centralised Anaerobic
Centralised Thermal
Hydrolysis + Anaerobic
kg COD emitted/kg dry biosolids handled
CO2
Greenhouse Gas Emissions
Neptune Workshop, Université Laval, Québec, March 25-26, 2010
Mesophilic Income (option b)
2016 per tonne wet biosolids
Cogen
electrical,
$4.32
Biosolids
charges,
$52.50
Mesophilic Expenditure (option b)
2016 per tonne wet biosolids
Polymer, $3.40
Disposal, $29.20
Maintenance,
$3.36
Staffing, $1.19
Depreciation
Civils, $4.31
Depreciation
M&E, $4.97
Alum, $1.76
Nitrogen-
Carbon, $3.40
Nitrogen
Aerators, $1.25
Engineering
Overheads,
$3.25
Cost – Mesophilic Alternative
Neptune Workshop, Université Laval, Québec, March 25-26, 2010
Thermal Hydrolysis Expenditure (option f)
2016 per tonne wet biosolids
Polymer, $2.40
Potable water,
$0.15
Maintenance,
$6.01
Staffing, $1.19
Depreciation
Civils, $7.31
Depreciation
M&E, $9.29
Engineering
Overheads,
$5.79
Nitrogen
Aerators, $2.11Nitrogen-
Carbon, $5.77
Alum, $2.99
Disposal, $6.05
Thermal Hydrolysis Income (option f)
2016 per tonne wet biosolids
Cogen
electrical,
$6.67
Biosolids
charges,
$43.12
Cost – Thermal Hydrolysis
Neptune Workshop, Université Laval, Québec, March 25-26, 2010
Key Outcome 2 – Neptune
Thermal hydrolysis produces coloured
compounds. Colour production is
dependent on temperature. Anaerobic
degradability is not.
Dwyer J, Starrenburg D, Tait S, Barr K, Batstone DJ, Lant PA. (2008). The impact of thermal
hydrolysis operating temperature on colour production and biodegradability of waste activated
sludge. Wat Res. 42(18): 4699-4709.
Neptune Workshop, Université Laval, Québec, March 25-26, 2010
Colour from THP is in effluent
• Advanced BNR with UV
disinfection
• Downstream membrane
filtration
• Compounds identified as
large humics by Ex-Em
Spec
• Failed quality measures
during thermal
hydrolysis operations
Neptune Workshop, Université Laval, Québec, March 25-26, 2010
Results variation in temperature
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0 5 10 15 20 25
THP 145C
Neptune Workshop, Université Laval, Québec, March 25-26, 2010
Results variation in temperature
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0 5 10 15 20 25
Time (d)
THP 165C
Neptune Workshop, Université Laval, Québec, March 25-26, 2010
Key Outcome 2 – Neptune
Thermal hydrolysis greatly increases
degradability, but there is still a basic
dependency on sludge age.
Batstone DJ, Tait S, Starrenburg D. (2009) Estimation of hydrolysis parameters in full-scale
anerobic digesters. Biotech. and Bioeng. 102(5): 1513-1520.
Batstone, DJ, Balthes, C., and Barr, K. (2010) “Model Assisted Startup of Anaerobic Digesters
Fed with Thermally Hydrolysed Activated Sludge”. Submitted Wat. Sci. Tech Feb 2010.
Neptune Workshop, Université Laval, Québec, March 25-26, 2010
Model Based Analysis
0
1000
2000
3000
4000
5000
6000
7000
0 50 100 150 200 250 300 350 400 450
Ga
s F
low
(N
m3 d
-1)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
fd
Digester 1
Neptune Workshop, Université Laval, Québec, March 25-26, 2010
On Both Digesters
0
1000
2000
3000
4000
5000
6000
7000
0 50 100 150 200 250 300 350 400 450
Time (d)
Ga
s F
low
(N
m3 d
-1)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
fd
Digester 2
Neptune Workshop, Université Laval, Québec, March 25-26, 2010
Indicated a relationship
0.3
0.35
0.4
0.45
0.5
0.55
0.6
0.65
0.7
5 10 15 20 25 30
Upstream Sludge Age (d)
De
gra
da
bility
Activated
Sludge
Hydrolysed
Neptune Workshop, Université Laval, Québec, March 25-26, 2010
Conclusions
Thermal hydrolysis is cost neutral but greenhouse
negative. Costs are shifted to capital expense
instead of operating expense.
Thermal hydrolysis produces coloured compounds.
Colour production is dependent on temperature.
Anaerobic degradability is not.
Thermal hydrolysis greatly increases degradability, but
there is still a basic dependency on sludge age.