1. BIOETHANOL PRODUCTION FROM FOOD AND AGRICULTURAL WASTE AND ITS APPLICATIONS 
V. Beschkov, K. Semkov, D. Yankov
Institute of Chemical Engineering, Bulgarian Academy of Sciences,
1113 Sofia, Bulgaria
7th World Congress on
Petrochemistry and Chemical Engineering, Atlanta, November 13-15, 2017

2. Hundreds of millions years planet history
Fossil fuels release in the atmosphere carbon dioxide stored underground for millions of years.
For one instance of the planet history man polluted it with waste accumulated for millions of years.
The natural vegetation is not capable to assimilate it.
-pulse
Hundreds of millions years planet history
History of humanity
THE CARBON CYCLE SHOULD BE CLOSED FOR FUELS PRODUCED NOW!!!

3. Problem: Greenhouse gas reduction?

4. Renewable energy sources:
Wind energy Solar energy Hydropower
Biomass...

5. Share of renewables, EU statistics, 2015

6. Biofuels are:
Ethanol;
Biodiesel;
Biogas;
n-Butanol.

7. Benefits of biomass as fuel:
Renewable and environmentally sustainable; replace (partially) the fossil fuels
Produced locally biofuels lead to energy independence and safety; reduce the dependence of fuel import;
Raw materials for organic products instead of oil;
Contribute to decrease of greenhouse gas emissions. All they are produced from biomass grown now in amounts that nature can utilize.
Drawbacks:
Stress on prices of food cereals (ethanol from starch); second generation raw materials (lingo-cellulose); third generation (algae);
Menace for biodiversity and environmental balance (plants for ethanol and biodiesel production);
Secondary air pollution (for crops cultivation).
Problems with waste treatment (e.g. waste glycerol at biodiesel production).

8. Bioethanol – some applications
Ethanol is:
easily transportable;
safe to handle and store;
non-toxic liquid fuel that can be used everywhere. Mishaps do not lead to significant environmental damage as is the case with oil.
Ethanol is already a major fuel in Brazil and in the USA and is making its way to Europe. Its current price is significantly lower than that of gasoline on a heating value equivalent while it qualifies for CO2 credits.

9. Bioethanol – some applications
Additive to gasoline and diesel;
E5G to E26G (5-26% ethanol, 95-74% gasoline)
E85G (85% ethanol, 15% gasoline)
E15D (15% ethanol, 85% diesel)
Octane booster;
Steam reforming to hydrogen: CH3CH2OH + 3H2O → 2CO2 + 6H2
Ethylacetate production:
CH3CH2OH + CH3COOH →CH3COO-CH2CH3
Solvent and feedstock for other chemicals and farmaceuticals;
Fuel cells.

10. Ethanol production from lignocellulose materials (2nd generation)
Reshamwala et al., Applied Biochemistry and Biotechnology, 1995.

11. Lignocellulose processing
A. Kroumov et al., Int. J. Bioautomation, 2015

12. Improved methods of producing anhydrous ethanol
Azeotropic distillation;
Extractive distillation;
Pressure swing adsorption (PSA) on molecular sieves;
Membrane separation.

13. Goals: To test other organic waste suitable for ethanol production;
To present PSA method for absolute ethanol production;
To demonstrate the fuel cell performance of ethanol.

14. Experimental (1) Raw material: stillage after ethanol distillation;
Methods: hydrolysis (alkaline (NaOH), ammonia, acid (1% H2SO4) and enzymes);
Enzymes: -amylase and glucoamylase; cellulase.
Microbes: Saccharomyces cerevisae; Zymomonas mobilis).

15. Results and discussion (stillage)
Hydrolysis
Reducing sugars (mg/ml);
alkaline hydrolysis
Reducing sugars (mg/ml) by acid hydrolysis compared to alkaline one. (1) - 1% NaOH; (2) – 2% NaOH; (3) – 3%- NaOH.

16. Results and discussion (stillage)
Enzyme hydrolysis
Reducing sugars after addition of α–amylase and glucoamylase. (1) - 1% NaOH; (2) – 2% NaOH; (3) – 3%- NaOH; (4) – 1% NH4OH; (5) – 2% NH4OH; (6) – 6% NH4OH.
Reducing sugars after addition of cellulase. (1) - 1% NaOH; (2) – 2% NaOH; (3) – 3%- NaOH; (4) – 1% NH4OH; (5) – 2% NH4OH; (6) – 6% NH4OH.

17. Results and discussion (stillage)
Ethanol and reducing sugars at fermentation after acid hydrolysis. 14 g dm-3 ethanol.

18. Experimental (2)
Substrates: residual grain after ethanol fermentation (ground and not); potatoes cuttings. Hydrolysis: two-step enzyme hydrolysis (thermostable alpha- amylase with consequent saccharification by glucoamylase); Fermentation: industrial strain.

19. Consecutive acid and enzyme hydrolysis of residual grain
10 g grain + 50 ml 1% H2SO4, 1 bar, 30 min
Separation
100 ml phosphate buffer, pH 5.5
α-amylase + glucoamylase, 24 h, 60 oC
Separation
100 ml phosphate buffer, pH 4.65
Cellulase, 24 h, 45 oC
α-amylase – Fuelzyme - Verenium Corporation, USA
glucoamylase – Deltazym GA L-E5, Verenium Corporation, USA
cellulase – Onozuca R-10 - Yakult Pharma- Japan

20. Results (residual grain)

21. Ultrasonic treatment of residual stillage
10 g grain ml 1% H2SO4, 15 min ultrasound, 1 bar for 30 min

22. Results (continued) Ethanol yield (comparison)
Substrate
Reducing substances,
g dm-3
Ethanol concentration,
Ethanol yield (96% vol.),
ml EtOH/kg substrate
Residual grain (enzyme,
our data)
112 62
230
Potatoes cuttings (enzyme, 98 50
212
Stillage (acid, our data) 59
14,6
146
Wheat straw, alkaline peroxide (Saha&Cotta, Biotechnol. Prog., 2006)
41,5
18,9
290
Corn stalks, H2SO4 (Ballat et al., Progress in Energy and Combustion Science, 2008)
n.a.
196
Grain, acid (own data)
14,1
140

23. Anhydrous ethanol - pressure swing adsorption (PSA) based on molecular sieves

24. Synthesia SA, Gorna Oryahovitza, Bulgaria, 2008
PSA- our achievements
Synthesia SA, Gorna Oryahovitza, Bulgaria, 2008
99,96% ethanol; litres/day

25. Direct ethanol fuel cell (DEFC)
Anode:
C2H5OH +3H2O=12H+ +12e-+ 2CO2
Cathode:
3O2+ 12H+ + 12e- = 6H2O
Overall reaction:
C2H5OH + 3O2 = 2CO2 + 3H2O
Energy content of ethanol: 8.0 kWh/kg
Energy content of methanol: 6.1 kWh/kg
Energy content of hydrogen: 79 kWh/kg
Energy content of gasoline: 12,8 kWh/kg

26. DEFC - results
Current density : 70 A/m2
Power density: W/m2

27. Thank you for your attention!
Acknowledgement. This work was supported by grant
DFNI E02/16 of the Fund of Scientific Research, Republic of Bulgaria.