Algae WWT Biodiesel 5
Transcript of Algae WWT Biodiesel 5
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The sludge has a high N&P content and can be used as a fertilizer
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Jason Selwitz was a graduate student in Regenerative Studies at CalPoly Pomona shown here withdifferent strains of algae growing on primary wastewater. This research was conducted at the JohnT. Lyle Center for Regenerative Studies. http://www.csupomona.edu/~crs/ For a look at what is
happening around the planet regarding algae-based biodiesel production go to:http://peswiki.com/index.php/Directory:Biodiesel_from_Algae_Oil
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ABSTRACT
Two strains of green, freshwater microalgae,Chlorella protothecoides and Botryococcus braunii ,
were used in experiments to determine whether theycould individually enhance the quality of one liter ofprimary treated human wastewater. A third groupingof algal strains, from Pond #6 at the John T. LyleCenter for Regenerative Studies, was also utilized.The protocol established called for analysis of thealgal oil content using gas chromatography/mass
spectrometry.Over the course of five day residence times, waterquality improved as biochemical oxygen demandwas reduced, and ammonia was converted to nitrate.Algal oils were produced and extracted, althoughratios of key fatty acid methyl esters were lower than
anticipated. Results from using specific strains ofalgae to treat wastewater and produce biodieselcaliber oil offer the foundation for future research.While several projects throughout the world areunderway to commercialize production of biodieselfrom algae, the scientific literature recommendspairing such efforts with wastewater treatment. Asclimate change emerges, the need for expandedreserves of water coincides with interest to developdomestic sources of cleaner burning fuel.
Initial Algae-Wastewater-Biodiesel Research under the supervision of Dr. Stephen Lyon
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The following is a hypotheticalmodification of a wastewater
treatment facility.
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A Regional Wastewater Control Facility discharges 30 MGD into a local river
Possible Reconfiguration of a Regional Wastewater ControlFacility to Yield Multiple Benefits
treatment wetlandsdesigned to removealgae solids
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General flow patterns of the water from the treatment facility through the oxidation
ponds, wetlands and to the dissolved air flotation (DAF) tanks. The green line indicates
the flow of the concentrated algae solids back to the first oxidation pond.
post wetlands treatment includes:ammonia stripping towers, DAF,chlorination, dechlorination anddischarge
Free surface constructedwetlands designed toremove algae solids
Oxidation Pond #1Oxidation Pond #2
Oxidation Pond #3
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Effluent from theconstructed wetlands
entering the DAF tanks
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Algae sludge being concentrated atthe surface of the DAF chambers
before being pumped back tooxidation pond #1.
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Theoretical reworking of the oxidation ponds where Hypalon® curtains with floating tops andweighted bottoms allow for serpentine flow within each pond to develop more of a plug flow throughthe three ponds. This allows for more thorough nutrient stripping by the algae. The influent to thepond contains a pure strain of algae grown in photobioreactors. The algae are filtered off after
leaving oxidation pond #3 and the water goes through a final polishing stage in the constructedwetlands.
algaefiltration
system photobioreactor providesinoculum for the ponds
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Examples of large-scale algae culturing operations throughout the world
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Examples of simple algae
concentration and processing
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What to do with the algae biosolids?
• All planktonic algae produce oil in the form of triglycerides to keepthem buoyant in the water column. In some species, the oil contentof the algae is 40-60% of its dry weight. For the algae in the oxidationponds it is assumed that the percentage of oil is 15%.
•The relatively simple mixture of the oil with sodium or potassiumhydroxide and methanol plus heat yields a commercially viable fuel.Biodiesel from algae produces far more fuel per acre of land thanvegetable oil sources.
• The oil needs to be separated from the algae by various means(chemical, mechanical, thermal, etc).
• The algae biomass can be added to the digester to produce more
methane.
• The flow chart on the next page shows the outcome of modifyingthe current operations at the facility. The boxes with the double linesindicate a beneficial end product.
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ABalgae biomass
reclaimedwastewater
NaOH/KOH
methanol
heat*
Biodiesel
Chemical feedstock forphytochemicals and/or
polymer production
Sludge digester for methane production
Electricity production via cogeneration
Exhaust gases are bubbled into the oxidation ponds toabsorb carbon dioxide and promote algae growth,possible carbon credits for removal of greenhouse gases
algaeoil
Effluent fromOxidation Pond #3
separation of algaefrom the water
ConstructedWetlands
* there are alternative biological, chemical and physicalprocesses that are being developed to produce biodiesel
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15500.7184935.402735.4214988.606813.0045420400
11625.5363701.552051.5611241.455109.7534065300
7750.3642467.701367.717494.303406.5022710200
3875.1821233.85683.853747.151703.2511355100
1937.5910616.93341.931873.58851.635677.5050
(15% of TSS)
tons/ yearlbs/ daytons/ yearlbs/ dayKg of oil/dayKG total/ daymg/L
biosolidsbiosolidsoil yieldoil yieldTSS@ 30 MGDTSS
The current TSS values leaving Oxidation Pond #3 are 30-70 mg/L. Under controlledculturing conditions including the venting of carbon dioxide from the cogeneration plant
there could be a substantial increase in the algae biomass produced in the oxidationponds. Estimates are given below for the yield of oil and biosolids for a TSS range of50-400 mg/L assuming an oil content of 15% of the dry weight of the algae. The oil
would go to biodiesel production and the biosolids could be used as a chemicalfeedstock for polymer production or for more cogeneration by adding the algae
biosolids to the digester.
e.g. 683.85 tons/year = 1,367,700 lbs/year ÷ 7.34 lbs/gal = 186,335 gal/year