HomeMy WebLinkAbout06. (Handout) Algae Wastewater Nexus Opportunities and Challengesr,!;- 05-, 1
Algae Wastewater Nexus
Opportunities and Challenges
REEP Committee Meeting
March 11, 2014
Dan Frost, PE
Associate Engineer
Chair of WEF Algae Technologies Task Force
CI
Protecting Public Health and the Environment
L,
1 of 12
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Why Talk about Algae?
• Rising energy costs ($100 /bbl) -> Rising alternative fuel demand
• Algae provides higher productivity than other crops
• Nutraceuticals, therapeutics, antioxidants /anticancer agents
• Spi ru l i na -$44k /ton of biomass
• Red carotenoid astaxanthin pigment ~$10M /ton ($:100k/ton
biomass)
• Requires water supply, nutrients ($$$)
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Algae Wastewater Treatment Nexus
• Abundance of water and nutrients available (resource
recovery potential)
• Offset mechanical treatment costs (BOD, N, P removal)
• Reduce GHG emissions by offsetting fossil fuel
demand /energy for mechanical treatment
• Resource recovery again (water, digestion, biofuels, etc.)
Sun
CO2
N
I
02
Organics
(e.g. BOD)
•
CN 2
I
Reduce District GHG Emissions?
Algae:
Wastewater:
A
C:N:P = 50:8:1
C:N:P = 20:8:1
dd COZ (flue gas) ..j
V/0000���
Reduce GHG Emissions (depends)
Avoid /Reduce Cap and Trade Costs
Partial /Complete Nutrient removal
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A WS,
ial
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Every Opportunity Comes with aChallenge.:-
• Closed Loop Photobioreactors are complex and expensive to
operate and maintain (require water for cooling)
• Open High Rate Ponds require a lot of land ( >10 acres /MGD)
• Biodiesel processing is complex and expensive
(Industry less focused on biodiesel, more focused on ethanol/
neutraceuticals)
• Energy savings from algae digestion depend on
dewatering / hauling cost
• Efficient algae harvesting is costly F- Achilles heel
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CCCSD — Feasibility Study Findings
• 100+ acres available (wet weather basins)
• 6.6 MGD system (HRPs, harvesting, digesters, etc.)
Economic evaluation depends on R &D break - throughs
and reasonable assumptions!
• Capital Cost = $5M to $25M
• 0 &M Savings =None to $400,000 + /year
• Simple payback is >12 years (or never)
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Assumptions Impact Costs
• Reduction in wet weather storage acceptable
• Pond liner vs. native soil for high rate ponds
• Harvesting technology used (bioflocculation vs. DAF)
• Biomass productivity achieved (seasonal performance)
• Basis for secondary treatment offset costs
• Solids handling/disposal/reuse options
• GHG Cap and Trade offset costs (impacts by landfill gas
availability)
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CCCSD — Feasibility Study Challenges
• Economic evaluation depends on assumptions used
• Reduces wet weather storage capacity
•Treatment limited to 6.6 mgd (10 -15% N removal from plant
influent)
• Available CO2 supply may limit size of algae system (open
ponds have 15 -30% CO2 transfer efficiency)
• 0 &M complexity (operating parallel treatment system)
• Odor potential
• Reliability concerns (seasonal, weather - dependence)
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Next Step Recommendations
• Continue to track algae R &D and grant funding for research
• Assess interest from local refineries
• Reconsider algae for treating digester digestate (Treatment Plant of
the Future ?)
• Consider technoeconomic evaluation if major issues are resolved (e.g.
reduced wet weather storage) - $31,000
• Pilot study if technoeconomic evaluation looks promising - $95,000
(materials and consulting only)
Regional
High Rate
Pond Algae
Production
Farms?
Photobioreactors
for Community
Enhancement?
-(-. Ai-
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