Grantee Research Project Results
Final Report: Waste to Fuel: Design of a Landfill Algae Bioreactor
EPA Grant Number: SU835081Title: Waste to Fuel: Design of a Landfill Algae Bioreactor
Investigators: Olson, Mira S. , Cairncross, Richard A. , Davis, Edward Christopher , Hurd, Eliya M. , Mundackal, Ashley , Rowntree, Bob , Comer, Carolyn , Lister, Eric , Hughes, Erin , Sniffen, Kaitlin , Wenrick, Matthew , Sparaco, Megan , Spatari, Sabrina , Kilham, Susan , Ahmed, Tausif
Institution: Drexel University
EPA Project Officer: Hahn, Intaek
Phase: I
Project Period: August 15, 2011 through August 14, 2012
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2011) RFA Text | Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Air Quality , P3 Challenge Area - Safe and Sustainable Water Resources , P3 Awards , Sustainable and Healthy Communities
Objective:
This project tests the viability of producing valuable energy products from landfill waste streams, and provides a site‐specific evaluation of the economic and technical feasibility of a strategy to combine waste remediation and renewable liquid fuel production in one integrated operation. The economic feasibility of cultivating algae for liquid fuel production may be attained by coupling algae biodiesel production with other processes, in this case treatment of landfill leachate. A process design has been developed and evaluated for a fullscale algae production plant at a landfill in Delaware. In addition, a pilot‐scale algae bioreactor has been designed for the same site based on bench‐scale laboratory experiments and techno‐economic analyses, for use as a future research facility.
The objectives of this project are to:
- Evaluate the technical and economic feasibility of a full‐scale on‐site algae production plant using leachate from landfill waste streams, and
- Design a pilot‐scale surface‐pond algae bioreactor using on‐site landfill leachate as a feed stock.
The design of the pilot‐scale algae bioreactor is informed both by full‐scale technoeconomic analyses and by bench‐scale laboratory experiments designed to determine optimal design parameters, including leachate:pond water dilution, harvesting time for optimal algal oil content, and the use of chitosan as a flocculant for harvesting mature algal cells
Summary/Accomplishments (Outputs/Outcomes):
A series of bench‐scale experiments of algal growth in leachate collected from an active landfill were performed to determine the optimum dilution of leachate to support growth. Results confirm the ability of C. vulgaris to grow on dilutions of leachate up to 15% (leachate:water) with growth yields comparable to cultures grown in nutrient replete growth medium. A stoichiometric analysis of algal growth on 15% leachate reveals that phosphorous and CO2 are limiting; CO2 may be supplied by bubbling air or CO2/air mixtures through the growth medium.
A full‐scale algae production plant was evaluated for a specific landfill site in Delaware using diluted leachate as the growth medium. The process takes the leachate streams from the landfill, which would otherwise be sent for cost‐intensive remediation, and uses them as nutrients to grow algae for eventual harvesting of bio‐oil. The costs for leachate remediation are offset by the use of the leachate streams in the plant. The bio‐oil produced via this process is to be of a quality comparable in cost and purity to currently available alternative oil sources such as soybean oil and rapeseed oil. Important unit operations in the process include feed stream preparation, algae ultization, flocculation, dewatering, and lipid extraction.
A techno‐economic analysis of the plant suggests that the technology is technically feasible, but economically impractical, assuming current operation standards and assumed literature values for process reactions rates and yields. An economic analysis was performed on the entire process using CAPCOST. The capital costs required for the process, the operating costs needed to run the plant and the initial return on investment were all estimated. One of the major sources of revenue for this process plant is the offset of leachate remediation costs that happens as a result of the usage of the leachate as a feed stream. From current estimates, the operation of the plant results in an annual savings of up to $226,358 for the landfill. The amount of revenue generated by the production and sale of lipids comes to $41,610 per year. From these channels of revenue, it was calculated that the estimated fixed capital investment on this project would be $1.41 million, resulting in a projected discounted cash flow rate of return (DCFROR ) of ‐3.18%, assuming a 15‐year life span of the plant. Although this suggests that the process is not yet economically feasible, a great number of the production rates, reaction rates and yield values had to be estimated from the literature, suggesting a pressing need for the design of a pilot‐scale algae bioreactor facility both for research of more efficient cultivation, dewatering and extraction processes, and for direct measurement of more realistic production rates and efficiencies.
A pilot‐scale algae bioreactor was designed for a specific landfill site in Delaware. The final design is a series of raceway ponds, followed by a combined coagulation, flocculation and settling tank, and a dewatering filter press. The bioreactor has been sized to fit on available land at a local landfill and will be housed within a greenhouse to facilitate year‐round cultivation. The bioreactor relies on nutrients from leachate collected from an active area of the landfill, to be diluted with either collected stormwater (or at this particular site with weak leachate from a more mature area of the landfill), CO2 supplemented via gas diffusers, chitosan as a flocculating agent and a final filter press to yield an algae filter cake with 55% solids.
Conclusions:
Cultivating algae for liquid fuel production is currently touted as one of the most promising solutions to our growing demand for energy. Production of biodiesel from algae is currently thought to be technically, but not yet economically, feasible at full‐scale. Economic feasibility may be attained by coupling algae biodiesel production with other processes, in this case leachate treatment and CO2 emission reduction at landfill sites, however specific growth yields and remediation potential are not yet known. Bench‐scale laboratory experiments have confirmed the feasibility of simultaneously growing algae while treating landfill leachate, and full‐scale economic models have been developed to assess the economic feasibility of cultivating algae for biofuel using landfill waste streams. The primary output of this P3 project, the design of a pilot‐scale algae bioreactor using landfill waste streams, is complete and may be used to construct such a facility on‐site at a landfill during Phase II. This pilot‐scale bioreactor would be the first of its kind and could be used to test this promising technology application, as well as optimize growth yield and efficiency to enhance the overall economic feasibility. Potential outcomes of the next phase of this work include a new and sustainable source of liquid fuel, reduction in the transport and required treatment of hazardous landfill leachate, and reduction in CO2 emissions from MSW landfills.Journal Articles:
No journal articles submitted with this report: View all 1 publications for this projectSupplemental Keywords:
Biodiesel, waste to energy, hazardous waste remediation, bio‐based feedstocksThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.