Grantee Research Project Results
Final Report: Linking Wastewater Purification and Biofuel Production
EPA Grant Number: SU834715Title: Linking Wastewater Purification and Biofuel Production
Investigators: Venable, Mark E. , Horse, Kyle American , Gorowski, Chase , Herrin, Jacob , Houser, James , Wolf, Lauren , Podbielski, Melanie , Hambourger, Michael , Cutshall, Michael , Tuberty, Shea , Boozell, Thalia , Sakamachi, Yosuke
Institution: Appalachian State University
EPA Project Officer: Page, Angela
Phase: I
Project Period: August 15, 2010 through August 14, 2011
Project Amount: $10,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2010) 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:
Wastewater treatment has long been a problem. Treatment of municipal wastewater treatment is expensive and still releases enough nutrients to cause environmental problems and these systems are not designed to treat pharmaceuticals. Livestock waste is not really treated but is sprayed onto agricultural fields. In many of these situations most of the nutrients simply wash into streams during rains. Because livestock operations operate on tight financial margins it is not economically feasible to treat the waste properly. In most of these situations there is serious environmental damage that occurs.
In both situations the waste is a problem that we pay to get rid of. Nutrients are in reality a very valuable resource and we should work hard to conserve this resource. This project set out to design, construct and test a new type of wastewater treatment system based on algae. Algae can produce large amounts of oil and are being heavily researched as third generation biofuels. Nutrients are required algae for growth and wastewater provides a great potential for an input into biofuel production. Algae are currently being used in some settings for wastewater treatment, however, due to problems with harvesting the systems become quickly overgrown. We set out to design a system that provides facile harvesting and improved water purification. In our design algae are grown on a solid support that can be easily removed from the water and hung up to dry. This one feature solves one of the key problems in algae biofuel production. Secondly, the water passes through the filter so that the nutrients in the water come into closer proximity to the algae and will be more effectively removed.
In the system we used for this Phase I project algae are bound to a near-vertical, porous substrate. We used square plastic pipe with the side cut out and laid down on a slope that we refer to as a trough. Filters were made of cotton cloth fixed to a porous rigid support. A pumping system was installed to re-circulate the water repeatedly through the filters. Algae were grown in suspension, adjusted to a fixed concentration and loaded into the trough. After 3 days of recirculation algae were fixed on the material. The water was changed out and nutrients and estrogen added at fixed amounts. After 4 days of recirculation samples were removed to test nutrient and estrogen removal, biomass and lipid production. We worked to test and optimize the system by varying a number of parameters.
Summary/Accomplishments (Outputs/Outcomes):
In our initial experiments we designed and constructed an air-lift pump to avoid damaging algae as was expected. We found that this was unnecessary as the impeller-based fountain pump showed better growth. In subsequent experiments we used the fountain pumps for all phases. In our first three experiments we found that the phosphorous levels quickly went to zero. We realized that the phosphorous was reacting with the zinc in the galvanized coating of the wire mesh. We found a replacement backing by using a porous plastic sheeting (Gutter Guard). Once we were able to work through these initial setbacks we were able to test the capabilities of our system. We performed a nutrient uptake experiment at different nutrient concentrations. We found that the algae were able to effectively handle concentrations in the low ppm concentration range. Next, we investigated whether additional CO2 was needed to maximize algae growth and nutrient uptake. We added aeration with air alone or air plus 20% CO2. We found no increase in nutrient uptake or algae biomass with aeration. This shows that this design is self aerating. Next, we looked at the influence of the filters being flow through by blocking water flow through the filter by plastic wrap. Our results showed that nutrient uptake was equal as was algae growth. Algae adherence to the filter was better in the flow through filter. Early tests using solid algae supports have shown that Hardy Board, stone tile and rubber do not support algal growth nearly as well as the cotton material and that polymer landscape cloth functions as well as cotton. Estrogen was effectively removed from the wastewater. This result was remarkable in that within two days estrogen was barely detectable. This is a great improvement over traditional wastewater treatment.
Conclusions:
We designed a wastewater treatment system based on algae that may provide better overall functionality than current systems. We found that our design was effective at removing nitrate, phosphate and estrogen from water. The algae produced significant levels of oil over just four days and are simple to harvest.
Our design has proven effective at the bench scale in removal of nutrient and pharmaceutical contamination and is ready to be tested at pilot scale in an outdoor system with wastewater.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 1 publications | 1 publications in selected types | All 1 journal articles |
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Venable M, Podbielski M. Impact of substrate material on algal biofilm biomass growth. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH 2019;26(7):7256-7262 |
SU834715 (Final) |
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Supplemental Keywords:
wastewater, eutrophication, algae, biofuel, biocharThe 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.