The final project from the Bioprocessing class in the Biosystems Engineering curriculum.

1. Making High-Value Co-products
from Algal Bioprocessing
By: Evan Patrohay, Alec Popichak, and Aaron Reeser
BE 4380

2. Introduction
● Algal biofuels are a promising alternative to
our reliance on fossil fuels for energy
● Why is algae so great?
○ Take up less space than feedstocks, and don’t
require arable land nor potable water
○ ‘Carbon neutral’ + super carbon-capturing
○ Renewable + quick-growing
● Yet it is difficult to produce algal biodiesel
efficiently and cost-effectively
○ It takes a lot to grow, harvest, and retrieve the oil
out of that much algae!

3. Chosen Article
“Combined algal processing: A novel integrated
biorefinery process to produce algal biofuels and
bioproducts” (2016)
From the article:
“Algal Research”

4. Goals
● Create high-value co-products alongside algal biodiesel processing!
○ Split algae into its macro-components
■ Lipids (Biodiesel)
■ Sugars (Ethanol) → we focused on this!
■ Proteins (food processing)
● The two promising methods
○ Parallel Algal Processing (PAP) → we focused on this!
■ Separate fermentable liquids from solids
○ Combined Algal Processing (CAP)
■ Ferment the entire algal slurry
Want to create our biodiesel & ethanol:
EFFICIENTLY
ECONOMICALLY
SUSTAINABLY

5. Constraints/Considerations
● Algae must be grown in such a way as to optimize both sugar AND lipid yields
○ Grown in “Nitrogen-Deplete Media” for 6-9 days
● Centrifugation is very energy intensive (not sustainable)
○ Should replace with microfiltration where possible
● Source materials with sustainability in mind
○ Do a Life-Cycle Assessment!
● Create a process which will limit waste
○ And maximize energy efficiency!
● Find a method to split algae into its components
○ Dilute Acid Pretreatment

6. Questions
● Consumer
○ What is the “minimum fuel selling price”
(MFSP) of algal biodiesel?
○ How many “gasoline gallon equivalents”
(GGE’s) will be produced?
● Designer
○ What unit operations are necessary for the
design?
○ How much will the design cost?
● Sustainably-Minded Individual
○ What are the materials being used and their
environmental impacts?
○ How much reactants / water is necessary?
○ What will the byproducts and emissions be?

7. Literature Review
● Dilute Acid Pretreatment
○ Use 2% H2SO4 + 25% w/w biomass dilution
○ Efficiently breaks algae into macro-components
● Parallel Algal Processing (PAP)
○ Only the liquids are fermented into bioethanol
● Solid-Liquid Separation (SLS)
○ Used in PAP
○ Separate pretreatment slurry from protein- and lipid-rich
solids
● Combined Algal Processing (CAP)
○ Entire slurry fermented together
○ Algal carbohydrates are fermented into bioethanol
○ Algal lipids are transesterified into biodiesel

8. Design
Step 1: Bioreactor for
algae growth
Step 2: Centrifuge for
algae harvesting
Step 3: Batch
Reactor for
pretreatment
Step 4:
Microfilter for
fractionation
of slurry
Additional
mixing step

9. Step 1: Bioreactor
Reactants:
Ammonium: 16 mol
Bicarbonate: 14 mol
Carbon Dioxide: 92 mol
Hydrogen Phosph: 1 mol
Water: 92 mol
Products:
Biomass: 1 mol
Oxygen: 106 mol

10. Step 2: Centrifugation

11. Step 3: Batch Reactor
Described in Article

12. Step 4: Microfiltration
An RC of “0” means glucose
was filtered out

13. Evaluation of Design
● Designed to run for
7,900 hr/yr
○ Each batch takes 168 hrs
○ Represents 47 batches/yr
● Because algae need an
extended growth period to
accumulate lipids the process
takes awhile!
○ Could be remedied by adding
more bioreactors (at added cost)
○ Researchers are searching for
optimal nutrient / condition
combination

14. Material Evaluations
● Reactants
○ Ammonium
○ Bicarbonate
○ Carbon Dioxide
○ Hydrogen Phosphate
○ Sulfuric Acid (Pretreatment)
○ Water
● Products
○ Biomass
○ Oxygen
○ Sugars/Lipids/Protein
○ “Impurity” (byproducts of pretreatment)
227.80 kg/batch TOTAL
Limited waste + harmful byproducts
Generally safe & common reactants

15. Economic Evaluations/Budget
● $9.85 million investment
● Hoped to be offset by valuable co-products
● (Revenue = $0 because design is only partial!)
● Requires high-throughput reactors and
centrifuge
● Makes equipment more expensive

16. Life-Cycle Assessment
● Low energy process!!
○ Likely an underestimate but is
still very promising
● Very little waste / emissions
involved in design
○ Mostly oxygen gas!
● Sourcing of materials
○ Most come from mining
○ Ammonia comes from fossil
fuels (Haber Process)
● Potential for carbon capture
at upscale!!

17. Techno-Economic Analysis
Fuel Yield [GGE/ton] Fuel Cost [$/GGE]
Parallel Algal Processing
(PAP)
114 10.68
Combined Algal
Processing
(CAP)
126 9.91
Lignocellulosic 40-80 N/A
Our Model
Winner
Algal biofuels are still not yet feasible...but this represents an
important step!

18. Timeline

19. Conclusion
● The technology involving biofuels is fascinating and still
progressing
○ Combing less energy-intensive filtration (replacing centrifugation)
and CAP are excellent steps forward
● Life-Cycle Assessments for algal bioprocesses appear to
be more promising than many alternatives
○ Lower emissions + carbon capture + simple reactants = a good deal
● Algae possess higher TEA scores than lignocellulosic
biofuels
○ As they represent the better alternative, we must find ways to
increase their growth / production
○ Put less pressure on food / forestry industries
● More research is still needed to make algal biofuels
economically feasible → cheer our researchers on!!!

20. References/Patents
● Bilad, M.R., et. al. “Harvesting microalgal biomass using submerged microfiltration membranes.” Bioresource Technology. Vol. 111, May 2012, pgs. 343-352.
● Dassey, Adam J., et. al. “Harvesting economics and strategies using centrifugation for cost effective separation of microalgae cells for biodiesel applications.” Bioresource Technology. Vol. 128, Jan. 2013, pgs.
241-245.
● Dong, Tau, et. al. “Combined Algal Processing: A novel integrated biorefinery process to produce algal biofuels and bioproducts.” Algal Research. Vol. 19, Nov. 2016, pgs. 316-323
● Ebeling, James M., et al. “Engineering analysis of the stoichiometry of photoautotrophic, autotrophic, and heterotrophic removal of ammonia-nitrogen in aquaculture systems.” Aquaculture. Vol. 257, Jun. 2006.
● Google Patents. Q-20 Western Centrifuge. US No. 1940182A. “Means for discharging material from centrifugal baskets.” https://patents.google.com/patent/US1940812?oq=Q-20+Western+Centrifuge
● Google Patents. ZipperClave Pressure Vessel. US No. 7758560B2. “Hazardous material handling system and method.”
https://patents.google.com/patent/US7758560?oq=zipper+clave%C2%AE+pressure+vessels
● Koyande, Apurav, et. al. “Bioprocessing of Algal Bio-refinery: a review on current advances and future perspectives.” Bioengineered. Vol. 10, 2019. Issue 1.
● Li, Yun, et. al. “Separation of monosaccharides from pretreatment inhibitors by nanofiltration in lignocellulosic hydrolysate: Fouling mitigation by activated carbon adsorption.” Biomass and Bioenergy. Vol. 136
● Monavari, Sanam, et. al. “The influence of solid/liquid separation techniques on the sugar yield in two-step dilute acid hydrolysis of softwood followed by enzymatic hydrolysis.” Biotechnol Biofuels. Vol. 2,
Issue 6
● Park, Jeong-Hoon, et. al. “Optimization of batch dilute-acid hydrolysis for biohydrogen production from red algal biomass.” International Journal of Hydrogen Energy. Vol. 38, Issue 14, May 2013, pgs. 6130-
6136.
● Silva, Carlos Eduardo de Farias, et. al. “Dilute acid hydrolysis of microalgal biomass for bioethanol production: an accurate kinetic model of biomass solubilization, sugars hydrolysis and nitrogen/ash balance.”
Reaction Kinetics, Mechanisms, and Catalysis. Vol. 122, Sept. 2017, pgs. 1095-1114.
● Sun, Amy, et. al. “Comparative cost analysis of algal oil production for biofuels.” Energy. Vol. 36, Issue 8, Aug. 2011, pgs. 5169-5179.