View
217
Download
3
Category
Preview:
Citation preview
Improving Anaerobic Conversion Improving Anaerobic Conversion of Pulp Mill Secondary Sludge to of Pulp Mill Secondary Sludge to
Biogas by Pretreatment Biogas by Pretreatment
Nicholas Wood, Honghi Tran and Emma MasterUniversity of Toronto
TAPPI EPE ConferenceMemphis, TN, October 12-14, 2009
Wastewater TreatmentWastewater Treatment
PrimaryTreatment
Waste Water
PrimarySludge
TreatedEffluent
SecondarySludge
Dewatering/Incineration/
Disposal
SecondaryTreatment
O2 CO2
2
EffluentDegassing Unit
Gas-liquid-solidseparator
Anaerobic granulesludge blanket
Influent distributionWastewater
Biogas
UpflowUpflow Anaerobic Sludge Blanketing Anaerobic Sludge Blanketing ((UASBUASB) Digester) Digester
3
Wastewater
Biogas(CH4, CO2)
Aerobic TreatmentUASB
Digester
TreatedEffluent
SecondarySludge
Dewatering/Incineration/
disposal
UASBDigesterUASB
Digester
CO2O2
Treatment System IncorporatingTreatment System IncorporatingUASBUASB DigesterDigester
4
Wastewater
Biogas(CH4, CO2)
Aerobic TreatmentUASB
Digester
TreatedEffluent
SecondarySludge
Dewatering/Incineration/
disposal
UASBDigesterUASB
Digester
Pretreatment
CO2O2
Treatment System Incorporating Treatment System Incorporating UASBUASBDigester and Sludge PretreatmentDigester and Sludge Pretreatment
5
ObjectiveObjectiveTo investigate the effectiveness of several pretreatment methods in increasing the anaerobic digestibility and biogas yield of pulp mill secondary sludge
6
Sludge SamplesSludge SamplesKraft Sludge (KS)
Bleached kraft pulp millUses an aerobic stabilization basin system to treat its effluent.
Sulphite Sludge (SS)Ammonium based sulphite pulp millUses an activated sludge system and an up-flow anaerobic sludge blanket (UASB) digester to treat several mill wastewater streams prior to aerobic treatment.
Methanogenic culture for SS and KSMicrobial granules formed in the UASB digester at the sulphite mill. Samples stored at 4oC in sealed plastic bagsAnaerobic granules stored at 4oC in glass serum bottles
7
Pretreatment MethodsPretreatment MethodsThermal Pretreatment:
170oC for 1 hour
Caustic Pretreatment:NaOH pellets were dissolved in the sample slurry (pH 12)140oC for 1 hour, pH adjusted to 7.
Sonication Pretreatment: Sonicated at 20 kHz to induce cavitation at an intensity of 1 kW/L, using a tubular sonication unit
8
Sludge CharacterizationSludge CharacterizationChemical compositionTSSVSSCODProteinBiogas Production
Biochemical methane potential (BMP) assay
9
Sludge AnalysisSludge AnalysisSulphite
Sludge (SS)Kraft
Sludge (KS)TSS, g/L 8.7 17.9VSS, g/L 7.3 13.9COD, g/L 12 27Soluble COD, % of total 12 1.1Carbohydrates, g/L 0.8 2Soluble carb., % of total 7.4 0.5Protein, g/L 3.9 4.6Soluble protein, % of total 0.43 0.13pH 7.4 7Sulphate, g/L 0.2 0.6Calcium, g/L 0.19 0.89Iron, g/L 0.18 0.04
10
0
20
40
60
80
100
Thermal Caustic Sonication
Red
uctio
n in
VSS
(%)
Sulphite SludgeKraft Sludge
Effect of Pretreatment on Effect of Pretreatment on VSSVSS
11
0
20
40
60
80
100
Untreated Thermal Caustic Sonication
Solu
ble
CO
D (%
)
Sulphite SludgeKraft Sludge
Effect on Soluble CODEffect on Soluble COD
12
0
20
40
60
80
Untreated Thermal Caustic Sonication
Solu
ble
Car
bohy
drat
es (%
)
Sulphite SludgeKraft Sludge
Effect on Soluble CarbohydratesEffect on Soluble Carbohydrates
13
Sulphite SludgeKraft Sludge
Effect on Soluble ProteinEffect on Soluble Protein
0.0
0.4
0.8
1.2
1.6
2.0
Untreated Thermal Caustic Sonication
Solu
ble
Prot
ein
(g/L
)
14
Biogas Produced from SSBiogas Produced from SS
0
0.05
0.1
0.15
0.2
0.25
0.3
0 5 10 15 20 25 30 35Time (days)
Cum
ul. B
ioga
s Pr
oduc
ed(L
/gC
OD
)
Untreated
Thermal
Caustic
Sonication
15
Biogas Produced from KSBiogas Produced from KS
Thermal
Caustic
0
0.05
0.1
0.15
0.2
0.25
0.3
0 5 10 15 20 25 30 35Time (days)
Cum
ul.B
ioga
sPr
oduc
ed(L
/gC
OD
)
Sonication
Untreated
16
Effect on Biogas ProductionEffect on Biogas Production
Sulphite Sludge
Kraft Sludge
0.0
0.1
0.2
0.3
0.4
Untreated Thermal Caustic Sonication
Tota
l Bio
gas
Prod
uctio
n(L
/gC
OD
)
17
Biogas Production vs. Soluble Biogas Production vs. Soluble CarbCarb. .
0
5
10
15
20
25
30
0 1 2 3 4Soluble Carbohydrates Added (mg)
Tota
l Bio
gas
Prod
uctio
n (m
L)
y = 6.02x + 3.63R2=0.96
y = 4.52x + 1.49
R2=0.90
Sulphite Sludge
Kraft Sludge
18
SummarySummaryEffects of thermal, caustic and sonication pretreatment methods on anaerobic conversion of SS and KS to biogas were investigated. Biogas production from untreated SS was four times higher than that from untreated KS
19
SummarySummaryThermal pretreatment was the most effective in improving the rate and extent of biogas yield of SS and KS sludges; followed closely by caustic pretreatment; sonication was the least effectiveSoluble carbohydrate content may be used as an indicator for the biogas production potential
20
! Alberta Pacific! Alberta Research Council/AFRI! DTE Petcoke! FPInnovations! Jammbco! Kiln Flame Systems! Zellstoff Celgar! Members of Research Consortium “Increasing Energy &
Chemical Recovery Efficiency in the Kraft Process”! NSERC
AcknowledgementsAcknowledgementsMembers of Research Consortium on
“Alternative Fuels for Lime Kilns”
21
Recommended