Biogas Production from Biological Sludge

Biogas Production from Biological Sludge

D. J. Lee Department of Chemical Engineering National Taiwan University

Sludge? ASM

Influent

Aeration tank Effluent

Primary settler

Secondary settler Recycled activated biomass

Primary sludge

Filtration

Secondary sludge (waste activated sludge)

Digester

Flocculation

Thickener

Dewatering facility Pretreatment

Settling

Biological Sludge Floc Floc is a common form of bioaggregates appearing in the wastewater treatment process. •Irregular shape; •Highly porous; •Compressible and fragile; •Inhomogeneous distribution of internal mass.

Sludge Floc

•A group of symbiotic microorganisms “embedded” in the extracellular Frolundpolymers (1994)

Biogas pH 5-6

pH 7-8

Anaerobic digestion Fermentative bacteria

Acidogenesis Hydrolysis

5%

20%

Complex biopolymers (Carbohydrate/ protein/ lipids) 75%

10%

35%

Organic monomers (sugar/ amino acids/ fatty acids) 30%

Long Long chain chain VFA(C3/C4/i-C4/C5/C6) VFA(C3/C4/i-C4/C5/C6) alcohol/methanol/lactate/formate/butanol/acetone alcohol/methanol/lactate/formate/butanolacetone

Acetogenesis

Acetogenic B.

13%

H2/CO2

17%

Acetate

Homoacetogenic B.

Methanogenesis

Acetoclastic B.

CH4/CO2/H2O 28%

72%

Hydrogenophilic B.

O △G ′ Step Fermentation

C6 H12O6 + 4 H 2O  → 2CH 3COO− + 2 HCO− + 4 H + + 4H 2 3

C6 H12O6 + 2 H 2O  → CH 3 (CH 2 ) 2 COO − + 2 HCO − + 3H + + 2 H 2 −

−

3

3C6 H12O6  → 4CH 3CH 2COO + 2CH 3COO + 2CO2 + 2 H 2O + 2 H + + H 2 → CH 3COO − + H + + 2 H 2 CH 3CH 2OH + H 2O 

Acetogenesis

→ CH 3COO − + H + + 3H 2 + HCO3− CH 3CH 2COO − + 3H 2O 

→ 2CH 3COO − + H + + 2 H 2 CH 3 (CH 2 ) 2 COO − + 2 H 2O  → CH 3COO − + 4 H 2O 2 HCO3− + 4 H 2 + H +  → CH 4 + 2 H 2O CO2 + 4 H 2  −

+

4 HCOO + 4 H  → CH 4 + 3CO2 + 2 H 2O

Methanogenesis

4CO + 2 H 2O  → CH 4 + 3CO2

→ CH 4 + CO2 CH 3COO − + H +  4CH 3OH  → 3CH 4 + CO2 + 2 H 2O

4(CH 3 ) 3 NH + + 6 H 2O  → 9CH 4 + 3CO2 + 4 NH 4+

-207 -135 -922 +10 +76 +48 -105 -130 -120 -186 -33 -309 -666

Step Denitrification

12 NO3− + C6 H12O6  →12 NO2− + 6CO2 + 6 H 2O 8 NO2− + C6 H12O6  → 4 N 2O + 6CO2 + 6 H 2O

12 N 2O + C6 H12O6  →12 N 2 + 6CO2 + 6 H 2O

Sulphate reduction

4 H 2 + SO42− + H +  → 4 H 2O + HS −

CH 3COO − + SO42−  → 2 HCO3− + HS −

4CH 3CH 2COO − + 3SO42−  → 4CH 3COO − + 4 HCO3− + H +

-1946 -632 -134 -152 -48 -151

Phase Fermenting Bacteria pH=5.2~6.3 YX=0.2g-VS g-COD-1 Faculative anaerobic

Acedogenesis and Methadogenesis pH=6.8~7.2 YX=0.03~0.05 g-VS g-COD-1 Obligate anaerobic Syntrophic reaction Interspecies hydrogen transfer

Propionate and H2 Propionate: account for over 30% of the electron flow Deterioration of propionate degradation Æ Decrease in VFA removal efficiency -10 1/2CH3CH2OH+1/2H2OÆ1/2CH3COOH+H2

-8

△Go(W)

-6

kCal

-4

H2+1/2CO2Æ1/2CH4+1/2H2O

1/2CH3COOHÆ1/2CH4+1/2CO2

1/3CH-2 3CH2COOH+2/3H2OÆ 1/3CH3COOH+1/3CO2+H2

0 Region for Ethanol to CH4

Region for Propionate to CH4

2 -8

-7

-6

-5

-4

-3

-2

-1

0

Log(H2) McCarty, P.L. and Smith, D.P. Anaerobic wastewater treatmen [J]. Environ. Sci. Technol., 1986,20:1200-1206

Through enzymes

Enhanced Hydrolysis

100 µ m

FT

p

Na-salt

TT

pH 3

1 1 H

US

Pre-hydrolysis Pre-hydrolysis of sludge is often applied in prior to the anaerobic digestion to: Disintegrate the suspended particles Decompose the insoluble organic molecules.

Alkaline treatment and ultrasonication were reported as effective prehydrolytic treatments.

Enhancing Digestion

Waste Activated Sludge Sampling from the recycled stream in the secondary treatment stage in St. Marys sewage treatment plant in Sydney, Australia. pH = 7.50 TSS = 10,700 mg/L. ρS = 1,612 kg/m3.

(a)

(b)

Strains in innoculum K8: (a) bacillus; (b) cocci.

Flocculation retards Digestion; while Ultrasonication Enhances it.

After sonication Original Flocculated

200

100

Before sonication Original Flocculated 0 0

10

20

30

40

90

100

Time (day) 10 -200

Before sonication Original Flocculated After sonication Original Flocculated

-250


8

ATP content (µg/L)

ORP (mV)

Methane production (g/kg DS)

300

-300

6

4

Before sonication Original Flocculated

2

0

-350 0

10

20

30

Time (Day)

40

90

100

0

10

20

30

Time (Day)

40

90

100

400

Before sonication Original Flocculated

df[4,3] (µm)

300

Poor digestion

200

80


60

40 0

10

20

30

Time (Day)

40

90

100

100 µm

Ori, 0 & 30 d

Floc, 0 & 30 d

Ori, 0 & 30 d

Floc, 0 & 30 d

Insufficient Challenge

0.11 W/cm3

Floc size (µm)

100

0.22 W/cm3 50 0.11 Watt/ml 0.22 Watt/ml

0.33 W/cm3

0.33 Watt/ml 0.44 Watt/ml

0 0

50 Sonication time (min)

100

R3 leachate

Rm effluent

COD (g/L)

14 7 0 2

R1 leachate

Rm CH4 yield

Rm CH4 content

80

21

0

R1/R2/R3 CH4 yield

4 6 8 operation time (day)

R2 leachate

R3 leachate

10

12

100 80

60

60 40 40 20

20 0

0 0

2

R1 leachate 8.0

Rm effluent

18

CH4 content (%)

R2 leachate

cumulative CH 4 yield (L)

R1 leachate 28


R2 leachate

10

R3 leachate

12

Rm effluent

7.0 12

pH

TVFA (g/L)

15

9 6

6.0 5.0

3

4.0

0 0

2


10

12

0

2


10

12

Full-Scale Landfill Site

Sustainable Landfill Simulative rainfall

Leacahte recycling

Leacahte recycling

Fresh

Fresh

Fresh

layer

layer

layer

Column No.1

No. 2

No.3-5

Pretreatment

Internal Circulation

Leachate Aerobic SBR

Gas sample Leachate

Ana UFB

Old layer

80

COD(g/L)

60

column column column column column

40

No.1 No.2 No.3 No.4 No.5

20

0 0

5

10

15

20

25

30

week 9.0

Biogas production

(a)

7.5

pH

6.0 column column column column column

4.5 3.0


1.5 0

5

10

15

20

25

30

week

100 column column column column column

CH4 concentration(%)

80

60


40

20

0 0

5

10

15 week

20

25

30

天子岭Site in HangZhu

pH 5-6

pH 7-8

Hydrogen from waste Hydrogen production by pure substance or mixture molasses (Tanisho and Ishiwata, 1994) glucose (Kataoka et al., 1997; Lin and Chang, 1999) crystalline cellulose (Lay, 2001) peptone (Bai et al., 2001) starch (Lay, 2001) Hydrogen production by concentrated wastewater (Bolliger et al., 1985 ; Liu et al., 1995 ; Ueno et al.,1996 ; Zhu et al., 1999) Hydrogen production by solid waste municipal solid waste (Lay et al., 1999) bean curd manufacturing waste (Mizuno et al., 2000 ) Hydrogen production by biological sludge ???

Min-sheng Sludge Concentration of wet solids

10,000~12,000 mg/L

Concentration of dry solids

1,429 kg/m3

pH value

6.4

Neutron particle size

71.6 µm

Zeta potential

-19.1 mV

TCOD

24,800 mg/L

SCOD

435 mg/L

alkalinity

325 mg/L

Elemental composition

C 34.3%、H 5.3%、N 5.4%、O 55 %

63µm 63µm 63µm 63µm

Tong-yi Sludge Concentration of wet solids

10,000 mg/L

Concentration of dry solids

1,450 kg/m3

pH value

6.7

Neutron particle size

59.7 µm

Zeta potential

-24.7 mV

TCOD

16,000mg/L

SCOD

86.7 mg/L

alkalinity

410 mg/L

Elemental composition

C 41.3%、H 6.6%、N 5.4%、O 46.7%

63µm 63µm

Strains screening

DNA sequencing

Finding optimal dealing parameters

Concentration

Pretreatment methods

Inhibitors

Measuring time points

Continuous anaerobic experiments

Gas production

Hydrogen productive substrates

Composition analysis

Strains screening (1) Screening

Strains screening (2) Add them individually

Test the ability of hydrogen production

M-B

M-D

M-F

M-G

The ability of hydrogen production is about 0.65-1.11 H2/kg DS

Species identification Extract DNA

PCR F8 R1510

Compare to the gene library

GCGGGNGNGGTNCC TAACACATGCAAGT CGTAACANGGTATT CCACANCAGNGNGC TGGACGGACNNGNA ACAGAGG…...

purification

purification

sequencing

Continuous sequencing

DNA Sequence

M-B M-D M-F M-G

Clostridium bifermentans

Clostridium bifermentans

Pretreatment flow chart Ultrasonication

Acidification

Original sludge

Pasteurization

Add BESA

Freeze-thaw treatment

Original sludge Filtrate

Pasteurized Filtrate

Ultrasonicated BESA adding Filtrate Filtrate

Acidified Filtrate

Freeze-thawed Filtrate

Sludge fermentation test - COD COD0 – COD of original biosolid SCOD – Soluble COD Min-sheng sludge

Tong-yi sludge

1.0

1.0

Original Sonicated Acidified Pasteurized Frozen/thawed BESA-inhibited

0.6

0.8

SCOD/COD0

SCOD/COD0

0.8


0.4

0.2

0.6

0.4

0.2

0.0

0.0

0

25

50

Time (hours)

75

100

0

25

50

Time (hours)

75

100

Sludge fermentation test –

Hydrogen production

CODi – COD of the substrate before testing

Min-sheng sludge

12

10

Yield of hydrogen(mg/g-CODi)

10


Tong-yi sludge

12


8

6

4


8

6

4

2

2

0

0 0

8hr

25

50

24hr Time (hours)

75

100

0

8hr

25

50

24hr Time (hours)

75

100

ludge fermentation test –

methane production

Min-sheng sludge

3.0


2.0


2.5

Yield of methane (mg/g-CODi)

Yield of methane (mg/g-CODi)

2.5

Tong-yi sludge

3.0

1.5

1.0

2.0

1.5

No CH4!!

1.0

0.5

0.5

0.0

0.0

0

25

50

Time (hours)

75

100

0

25

50

Time (hours)

75

100


pH measuring

Min-sheng sludge

8


7

Tong-yi sludge

8


7

6

6.5

6

pH

pH

6

5.5

5

5

5.5

4

4

3

3

0

25

50

Time (hours)

75

100

0

25

50

Time (hours)

75

100

Sludge fermentation test - ORP Min-sheng sludge

0



-100

ORP(mV)

ORP(mV)

-100

Tong-yi sludge

0

-200

-300 -300

-200

-300 -300

-400

-400 0

25

50

Time (hours)

75

100

0

25

50

Time (hours)

75

-350

100


Zeta potential

Min-sheng sludge

0

Tong-yi sludge

0

-12 -10

Zeta potential(mV)

Zeta potential(mV)

-10

-20

-18 Original Sonicated Acidified Pasteurized Frozen/thawed BESA-inhibited

-30

-20 -20

-30

Original Sonicated Acidified -32 Pasteurized Frozen/thawed BESA-inhibited

-40

-40

0

25

50

Time (hours)

75

100

0

25

50

Time (hours)

75

100


Particle size distribution Min-sheng sludge

400

Tong-yi sludge

1200

350

1000 300

800


df,avg(µm)

df,avg(µm)

250


200

150

600

400

70

100

90

200 50

35

0

0

25

50

Time (hours)

75

0 100

0

25

50

Time (hours)

75

40

100

Filtrate fermentation test - COD Min-sheng filtrate

Tong-yi filtrate

1.0

1.0


0.6

0.8

SCOD/COD0

SCOD/COD0

0.8


0.4

0.6

0.4

0.2

0.2

0.0

0.0 0

25

50

Time (hours)

75

100

0

25

50

Time (hours)

75

100

Filtrate fermentation test –

Hydrogen production

Tong-yi filtrate

60

60

50

50


40



Min-sheng filtrate

30

20

10


40

30

20

10

0

0 0

8hr

25

50

24hrTime (hours)

75

100

0

8hr

25

50

24hrTime (hours)

75

100


pH measuring

Min-sheng filtrate

Tong-yi filtrate

9

9


8

8

6

7

pH

pH

7


6

5

6.8

6

6

5

5.5 4

4

3

3 0

25

50

Time (hours)

75

100

0

25

50

Time (hours)

75

100


ORP

Min-sheng filtrate

Tong-yi filtrate

100

100


0

-100

ORP(mV)

ORP(mV)

0


-200

-100

-200

-300

-300 -300

-300

-400

0

25

50

Time (hours)

75

-350

-400 100

0

25

50

Time (hours)

75

-360

100

Filtrate fermentation test – Zeta potential Min-sheng filtrate

Tong-yi filtrate

0

0

-5

-5

-12 -10

Zeta potential(mV)

Zeta potential(mV)

-10

-15

-15 -20


-25

-30

-18

-15

-20

-25


-30

-35

-35

-24

-40

-40

0

25

50

Time (hours)

75

100

0

25

50

Time (hours)

75

100

Clostridium inoculum 產氫不增不減

產氫氣

氫氣不增不減

Clostridium sp. C-2

C-3 0

8

16

24 32

40

48

72 96 120 144 168 192 216 240

So… All pretreatments can assist hydrolysis of organic materials effectively. But not all of them help in producing hydrogen. The production of hydrogen increases markedly over 8-24 hr, and is consumed afterward. Freezing-thawing, pasteurization, and acidification assist hydrogen production. But adding BESA and ultrasonication retard it. Hydrogen production reaction occurs in liquid phase, while the existence of sludge would in some sense consumes the hydrogen.

Co-Production of H2 and CH4

H2 Filtrate

Sludge

Pretreatment

Filter

Hydrogen Fermenter

Cake

CH4

Methane Digester

Twin Fermentors

K8 inoculum 產氫

消耗氫氣累積甲烷

0 8 16 24 32 40 48 72 96 120 144 168 192 216

K8 240hr 厭氧消化

Clostridium

96hr 厭氧消化

K8

至240hr 厭氧消化

Co-Production

H2

CH4 140

1.4

sludge sludge+clo frozen/thawed acidified alkalized

1.2 1.0 0.8 0.6 0.4

100

original sludge sludge+clostridium frozen/thawed acidified alkalized

80

60

40

20

0.2

0.0 0

120

yield of CH4 (g/kg DS)

Hydrogen content(g/kg DS)

1.6

100

200

Time(hrs)

300

400

0 0

100

200

Time(hrs)

300

400

TCOD

SCOD

12000

10000

TCOD(mg/L)

11000

10000

9000

8000

sludge sludge+clo frozen/thawed acidified alkalized noodle

8000

SCOD(mg/L)

sludge sludge+clo frozen/thawed acidified Alkalized noodle

6000

4000

2000

7000

6000

0

0

100

200

Time(hrs)

300

400

0

100

200

Time(hrs)

300

400

300

NH3-N(ppm)

250

200

150 original sludge sludge+clo freeze/thawed +clo acidified+clo alkalized+clo alkalized noodle+clo

100

50

0

0

100

200

Time(hrs)

300

400

frozen/thawed Fre/thaw

Basified sludge Alkalized

1200

1000

lactic acid acetic acid propionic acid butyric acid

1000

800

800


ppm

ppm

600 600

400 400

200

200

0

0 0

100

200

300

400

sludge+clo Time(hrs) Ori+clo lactic acid acetic acid propionic acid butyric acid

ppm

600

400

200

0 0

100

200

Time(hrs)

100

200

300

Time(hrs)

1000

800

0

300

400

400

500

600

Acidified Acidified

original sludge Original 400

2000 1800


1600 1400

lactic acid acetic acid propionic acid

300

ppm

ppm

1200 1000

200

800 600

100 400 200

0

0 0

100

200

Time(hrs)

300

400

0

100

200

Time(hrs)

300

400

K8 0

8 16 24 32 40 48 72 96 120 144 168 192 216

K8

Methane (g/kg DS)

4

3

2

1

0 0

100

200

300

Time(hrs)

400

500

Original sludge 70

Original

Methane (g/kg DS)

60

50

40

30

20

10

0 0

100

200

300

400

500

Time(hrs)

0

8

16 24

32 40 48

72 96 120 144 168 192 216

SUMMARY

pH 5-6

pH 7-8