Third-Generation - TeachEngineering

kissimmeemisologistBiotechnology

Dec 14, 2012 (4 years and 6 months ago)

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Algae is a Third
-

Generation Biofuel


Biofuel = fuel derived from
Biomass



First
-
, Second
-

and

Third
-
Generation


Food crops, waste
residues/abandoned land,
microalgae



Biofuel Examples
:


Bioethanol


Biodiesel


biogas




First
-

and Second
-
Generation Biofuels


Primarily from food crops


Corn


Sugar cane


Soybean


Palm

Third
-
Generation Biofuels


Biodiesel derived
from algae oil



Algae Oil is in the Lipids


Lipids:
provide energy storage and cell protection


Glycerolipids

-

mono,
di

& tri
-
substituted
glycerols

(
tryglycerol

lipids)


Fatty
acyls

-

long chain fatty acids


Glycerophospholipids

(phospholipids)


primary component of cellular membranes (lipid
bilayer
) and
binding sites for intra
-

and intercellular proteins



x
.


Photomicrograph of
Botryococcus

species, with oil droplets being released

Algal Strains


Species currently being studied for suitability as a
mass
-
oil producing crop



Botryococcus

braunii


Chlorella
protothecoides

(UTEX 25)


Dunaliella

tertiolecta


Gracilaria


Pleurochrysis

carterae


Sargassum


Nannochloropsis

salina

(1776)

Marine algae

Freshwater algae

Growing Algae Using WW


Requires Addition of
CO2


algal production is carbon
limited in
ww


low C:N ratio of
ww



No CO2 addition


Elevated daytime pH
from the algae’s use of
HCO3
-

as a carbon source
for photosynthesis and
release of hydroxide ions


Tertiary Treatment of WW Using Algae


High Rate Algal Ponds
(HRAPs)


Open Raceway System


Plastic or cement lined


Depth: 20
-
35 cm to
ensure adequate
sunlight



Waste CO2

Waste
water

Mature
Algae

Motorized
Paddle

Tertiary Treatment and Biofuel Production
of WW Using Algae in HRAPs

WW Treatment: Nutrient Removal


Design Parameters:


Depth (illumination)


Hydraulic Retention Time (biomass degradation at long
HRTs)



Typical Nutrient removal via Mixed algal culture:


Nitrogen (N): 40%
-
90% removal at temps btw 11 & 25 deg C


Phosphorus (P): 70
-
100% removal (at temps ~25 deg C)


Warmer Temps


higher phosphorus removal


Shallow cultures (~17 cm)


inc removal efficiencies
vs

deeper cultures (~33 cm)


Photobioreactors

Innovative Ideas for WW
Treatment using Algae

Conclusion



There are many advantages to using algae as a 3
rd

generation biofuel, but many challenges still remain to
ensure efficiency of
ww

treatment and algal lipid
production after scaling up for industrial
implementation.


Maintaining efficient production of lipids for biofuel
production while maximizing wastewater treatment has not
been perfected


Full scale industrial implementation of this technology has
not yet occurred


Future Research



Harvesting Algae


Autoflocculation

of algal cells in
suspension



Extraction Methods


efficient methods for lipid
extraction



Genetic Engineering of robust high lipid producing
strains that are fast growing