Bioconversion of wastes (wastewater
sludge, glycerol) to biodiesel
R.D. TYAGI
Canada Research Chair
Why biofuels? ---Energy crisis
Fossil fuel-
80%
of world energy demand
50%
of available oil – exhausted
Why biodiesel?
3Biodiesel
Renewable
Bio-degradable
Compatible
with diesel
engines
Comparable
energy
density
Non-toxic
Sustainable
What is biodiesel?
Oil/fat Alcohol Biodiesel (FAMEs) 100 Kg 10Kg Glycerol CatalystTransesterification
Alcohol: methanol (cheaper)
Catalyst: base or acid (FFA)
expensive
Fatty acid methyl esters
Problem of Glycerol?
5 0 200 400 600 800 1000 1200 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Millio n g allon sGlobal glycerol production
Alternative feedstock
Microbial oils:
Accumulate
high
lipid
(80% w/w)
Rapid
growth rate
Easy
to control
Does Not
require
arable
land
Problem
Affordable substrates
7
Wastewater Sludge:
Naturally
produced
Cost
free
(waste)
Rich in
C & nutrients
Disposal problem
Crude glycerol:
By-product
of biodiesel production
Cost
low
(
0.15 US$/kg
) or can be
free
Simple
Carbon
Oil Soap Glycerol
Process
Sludge Sludge+crude glycerolFermenter
Extraction
Transesterification
Glycerol +
Biodiesel
Sterilization 1210C, 30 min Oleaginous microbesProcess (fermentation)
9 Sludge Sludge+crude glycerolFermenter
Sterilization 1210C, 30 min Oleaginous microbes 0 5 10 15 20 25 30 35 40 45 0 20 40 60 SS an d Gl yc e ro l c o n ce n tr ation (g/L), lip id c o n te n t (% ) Time (h)Washed sludge+40 g/L glycerol
SS Lipid Glycerol
Higher SS was obtained with washed sludge (31 g/L) than unwashed sludge (23 g/L).
0 5 10 15 20 25 30 35 40 45 0 20 40 60 SS an d Gl yc e ro l c o n ce n tr ation (g/L), lip id c o n te n t (% ) Time (h)
Unwashed sludge+40 g/L glycerol
Sludge effect on lipid accumulation
Initial conditions: sludge SS=30 g/L; Alkaline thermal treated ; 10% innoculation
SS0 Pre-tretmant Glucose (g/L) Glycerol (g/L)
Washed Unwashed SSf Lipid
(%w/w) Lipid (g/L) 30 AT - - - UW 21.1 28 5.9 30 AT - 25 - UW 29.2 32 9.3 30 AT 25 - - UW 31.9 35 11.2 30 AT - 50 - UW 30.2 33.6 10.1 30 AT - 100 - UW 27.2 33.3 9.1 30 AT - 150 - UW 27.2 33.1 9.0 30 AT 40 W - 29.2 40.4 11.8 30 AT - 40 UW 22.5 35.2 7.9 35 AT - - W - 22.7 35 8 35 AT - 40 W - 48.0 40 19.2 MOR1 70 10.68 75.8 8.1
Process
11 Sludge Sludge+crude glycerolExtraction
Ultrasonication 60 Hz, 2800 W 60 Hz, 2800 W T. oleaginous Fungi-SK5Profile of biodiesel
Major:
Suitable for biodiesel
0 5 10 15 20 25 30 35 40 C 6:0 C8:0 C 10 :0 C 11 :0 C 12 :0 C 13 :0 C 14 :0 C 14 :1 C 1 5 :0 C 15 :1 C 16 :0 C 16 :1 C 17 :0 C 18 :0 C 18 :1 C 1 8 :2 C 18 :3 C 20 :0 C 20 :1 C 20 :2 C 21 :0 C 22 :0 C 22 :1 C 22 :2 C 23 :0 C 24 :0 C 24 :1 Fa tty ac id c o mp o sitio n fr ac tio n s (%)
lipid from original sludge
lipid from solo sludge fermentation lipid from sludge+glycerol fermentation lipid from sludge+glucose fermentation
Energy balance and Greenhouse Gas Emissions
(1 tonne sludge utilized)
GHG
emissions
13 sludge - extraction - transesterification Sludge - fermentation - extraction –transestrificationEnergy balance
0 2 4 6 8 10 12 Residue to landfill Residue to land application Residue for fermentation Sludge fermentation Pre-treated sludge fermentation Ne t ene rg y gai n per t onn e sl udg e us ed ( G J) -30000 -25000 -20000 -15000 -10000 -5000 0 5000 10000 G HG g ene ra tion per t onn e sl udg e us ed ( kg C O2 )Comparison of Energy Ratio
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5Ener
gy
r
atio (Outpu
t/I
np
ut
)
Cost of biodiesel production from sludge
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Co st o f b io d ie sel p ro d u ction (US $/ kg) 1.0 US $/kg: Cost of biodiesel production Sludge (11% p/p) - extraction - transesterification Sludge - fermentation - extraction –transestrification Alkaline+thermal sludge 15 LF= landfill LA=land applicationCost estimation of crude glycerol for biodiesel
production
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 L0.4 -2%-7 2 h -5 0LC-ch L0.4 -2%-7 2 h -6 0LC-ch L0.4 -2%-7 2 h -7 0LC-ch L0.4 -2%-7 2 h -7 0LC-ch L0.4 -2%-4 8 h -7 0LC-ch L0.4 -2%-3 6 h -7 0LC-ch L0.4 -2%-7 2 h -7 0LC-ch L0.4 -2%-7 2 h -7 0LC-slu d ge L0.4 -2%-4 8 h -6 0LC-slu d ge L1-2% -48 h -6 0LC-slu d ge L1.8-2% -48 h -6 0LC-slud ge L5-2% -48 h -6 0LC-slu d ge L1-2% -48 h -6 0LC-slu d ge L1-15 % -4 8h -60 LC -slu d ge L1-30 % -4 8h -60 LC-slu d ge L1-2% -48 h -6 0LC-slu d ge-0 .6 3 L1-2% -48 h -6 0LC-slu d ge-0 .6 0 L1-2% -48 h -6 0LC-slu d ge-0 .5 0 L1-2% -48 h -6 0LC-slu d ge-0 .4 L1-2% -48 h -6 0LC-slu d ge-$ L1-15 % -4 8h -60 LC-slu d ge-$ L1-30 % -4 8h -60 LC-slu d ge-$ H u ile d e p al me H u ile d e can o la H u ile d e to u rn eso l H u ile d e soj a Li p id p rod u ct ion co st ($/ kg )lipide content Time Nutrients Scale Methanol Yield Gycerol Cost (0.15$/kg)
0.4 million kg lipid/yr 1 million kg lipid/yr
1.11$/kg lipid
Conclusions
17
Medium
Sludge
Glycerol
Sludge
+
glycerol
Washed
sludge
+
glycerol
Quantity used 1 tonne sludge 1 tonne 1 tonne sludge
+ 1.3 tonne Glycerol 1 tonne sludge + 1.3 tonne Glycerol
Biodiesel
(product) 198 kg 220Kg 263 kg 411 kgGlycerol
(by-product) 20 kg 22Kg 26 kg 41 kgEnergy balance of biodiesel production
(heterotrophic microalage)Biodiesel produced from microalage cultivated in wastewater
Tra
Cultivation
Harvesting
Extraction
Recovery
Transportation
Drying
Wastewater
Sludge
Residual solid
Transesterification
Biodiesel
Biodiesel production from sludge
(one-step)
SEM images after ultrasonication
(glycerol medium) Trichosporon oleaginosus SKF-5 Before Before 520 kHz, 40 W 60 Hz, 2800 W 60 Hz, 2800 W 520 kHz, 40 W 21 Ultrasonication Ultrasonicationa
b
c
d
e
f
Energy balance and Greenhouse Gas Emissions
(1 tonne biodiesel produced)
GHG emission
-5 0 5 10 15 20 25 30 35 En e rg y b al an ce o f p e r to n n e b io d ie sel p ro d u ce d (GJ) -60000 -50000 -40000 -30000 -20000 -10000 0 10000 e n e rate d p e r to n n e b io d ie e l p ro d u ce d (k g CO 2 ) sludge - extraction- transesterification Waste - fermentation - extraction –transestrification CO2 - fermentation
- extraction –transesterification
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Ener
gy
r
atio (Outpu
t/I
np
ut
)
Biodiesel production from sludge
(two-step)
Wastewater
Sludge
Extraction
Residual solid
Lipid
Transesterification
Biodiesel
Step 2
Step 1
Different medium effect on lipid accumulation
0.00E+00 1.00E+08 2.00E+08 3.00E+08 4.00E+08 5.00E+08 6.00E+08 7.00E+08 8.00E+08 9.00E+08 1.00E+09 0 5 10 15 20 25 30 35 0 12 24 36 48 60 72 SS co n ce n tr ation (g/L) an d li p id c o n te n t (% ) Time (h) SS Lipid content CFU CFU (/ m L) Sludge medium 2.00E+09 4.00E+09 6.00E+09 8.00E+09 1.00E+10 1.20E+10 5 10 15 20 25 30 35 40 u co se, S S co n ce n tr ation (g/L) an d lip id c o n te n t (% ) SS Lipid content Glucose CFU CFU (/ m L) Sludge +glucose 35% lipid w/w 0.00E+00 2.00E+08 4.00E+08 6.00E+08 8.00E+08 1.00E+09 1.20E+09 1.40E+09 0 5 10 15 20 25 30 35 0 12 24 36 48 60 72 Gl yc e ro l, SS c o n ce n tr ation (g/L) an d li p id co n te n t (% ) Time (h) SS Lipid content Glycerol CFU CFU (/ m L) Sludge+crude glycerol 32% lipid w/w 28% lipid w/wInitial conditions: sludge SS=30 g/L; Alkaline treated; Glucose/glycerol conc.=25 g/L; 10% innocul.
Curde glycerol for lipid accumulation is comparable with glucose
Glycerol concentration effect on lipid
accumulation
27 0 5 10 15 20 25 30 35 40 45 50 0 5 10 15 20 25 30 35 40 0 12 24 36 48 60 72 SS c o n c. (g/L) an d Li p id c o n te n t (% ) Time (h)Original glycerol conc. 50 g/L
SS Lipid content Glycerol Gl yc e ro l c o n c. (g/L) 0 20 40 60 80 100 120 0 5 10 15 20 25 30 35 40 0 12 24 36 48 60 72 SS c o n c. (g/L) an d Li p id c o n te n t (% ) Time (h)
Original glycerol conc. 100 g/L
SS Lipid content Glycerol Gl yc e ro l c o n c. (g/L) 0 20 40 60 80 100 120 140 160 0 5 10 15 20 25 30 35 40 0 12 24 36 48 60 72 SS c o n c. (g/L) an d Li p id c o n te n t (% ) Time (h)
Original glycerol conc. 150 g/L
SS Lipid content Glycerol Gl yc e ro l c o n c. (g/L)
Sludge effect on lipid accumulation
Initial conditions: sludge SS=30 g/L; Alkaline treated ; 10% innoculation
0 5 10 15 20 25 30 35 40 45 0 20 40 60 SS an d Gl yc e ro l c o n ce n tr ation (g/L), lip id c o n te n t (% ) Time (h)
Washed sludge+40 g/L glycerol
SS Lipid Glycerol 0 5 10 15 20 25 30 35 40 45 0 20 40 60 SS and Gl yce rol co n ce n tr ati on (g /L), lip id c o n te n t (% ) Time (h)
Unwashed sludge+40 g/L glycerol
SS Lipid Glycerol