Biohydrogen and biodiesel co-production with treatment of high solid food waste
Agreement Number:
C0800272
Quarterly Report
March 31, 2008
Prepared by
Zhanyou Chi, Chenlin Li, Yubin Zheng and Shulin Chen
Bioprocessing and Bioproduct Engineering Laboratory
Department of Biological Systems Engineering
Washington State University
General Project information
Project objectives
This project will develop a two-step process to produce hydrogen and biodiesel with treatment of high solid food waste. The first step of this process is dark fermentative hydrogen production, in which the fermentative bacteria will use glucose derived from the organic waste carbon to produce hydrogen and volatile fatty acids (VFA) (e.g., acetate or butyrate). One third of the carbon is converted to carbon dioxide in the first-step process while two thirds of the carbon is converted to volatile fatty acids. In the second step, the remaining carbon in the form of VFA is used as a carbon feed to microalgae and/or yeast for simultaneous vector reduction and production of biodiesel.
This project has four main objectives as described individually in more detail below. The four objectives are to: (1) develop a lab-scale continuous bio-hydrogen production process from OFMSW; (2) optimize the culture conditions for lipid-producing yeast Cryptococcus curvatus using VFA from the bio-hydrogen production process as the carbon source; (3) test a continuous perfusion-bleeding culture of Cryptococcus curvatus with VFA as the carbon source; and (4) perform an overall mass/energy balance and system evaluation of the proposed process for regional and technical outreach and dissemination.
Project period: 1/1/2008—6/30/2009
Tasks / Deliverables / 2008 / 2009Quarter / Quarter
1 / 2 / 3 / 4 / 1 / 2
(1) Development of lab scale continuous bio-hydrogen production process with high solid organic waste as the feedstock / 1st and 2nd quarterly report
(2) Culture condition optimization of Cryptococcus curvatus using VFA as the carbon source (batch culture) / 3rd and 4th quarterly report
(3) Continuous perfusion-bleeding culture of Cryptococcus curvatus / 5th and 6th quarterly report
(4) System Design Extension and outreach / WSU website
(5) Final report / Final report
Reporting period: 1/1/2008—3/31/2008
Summary of progress to date by objective and deliverables
According to the original timeline start from 10/1/2007, the first objective, Development of lab scale continuous bio-hydrogen production process with high solid organic waste as the feedstock, suppose to be finished before 1/31/2008, and the second objective, Culture condition optimization of Cryptococcus curvatus using VFA as the carbon source (batch culture), would be started and have some preliminary data. Although the agreement was signed until January 2008, the work was startedbefore this. By now, both the first and second objective is undergoing. For the first objective, the lab scale continuous biohydrogen production process with glucose as the raw material has been established and the culture condition has been determined. The test with food waste as the raw material will be conducted in the next quarter, to accomplish all work of this objective. For the second objective, some preliminary data have obtained, and the culture condition for Cryptococcus curvatus has been optimized with batch cultures conducted with flask, except pH, which have to be conducted in a bioreactor with pH control. On the whole, this project is a little bit delay, caused by the delaying start time, but we are confident to catch up in the next quarter to fit in the original time schedule that ends at 6/30/2009.
Summary of project activities and main findings during the reporting period
1)Development of lab scale continuous bio-hydrogen production process
In the study of continuous biohydrogen production process with glucose as the raw material, the reactor was packed with chloroform treated granules, and long- term operation was conducted to investigate the factors influencing the upflow reactor. The result show that the HRT of the upflow reactor can beas low as 4 hours without decrease of hydrogen production yield. Initial pH and glucoseconcentration of the culture medium significantly influenced the performance of thereactor. The optimum initial pH of the culture medium was neutral and the optimumglucose concentration of the culture medium was below 20 g COD/L at HRT 4 hours. As HRT decreased, hydrogen productivity gradually increased. The yield of hydrogen fermentation, however, decreased when the HTR was shorter than three hours, owing to the overloading of the upflow reactor. With the optimized culture condition, experiment using food waste as the raw material will be conducted in the next quarter.
2)Culture condition optimization of Cryptococcus curvatus using VFA as the carbon source
In the optimization of Cryptococcus curvatus’ culture condition, it was found that the concentration of NH4Cl (A), MgSO4·7H2O (B), EDTA (C), CH3COOK(D), as well as pH (E) are the most significant factors for the result. With a central composite design experiment, an equation as below of was obtained to predict the result in certain condition of the variables.
biomass / =0.30
0.27 / * A
-0.03 / * B
-0.24 / * C
-0.68 / * D
0.54 / * E
0.31 / * C2
0.34 / * D2
-0.42 / * A * D
0.42 / * A * E
-0.42 / * B * C
-0.61 / * D * E
4.3 g/L of yeast biomass was obtained in the best culture condition in these experiments. The pH in the culture, however, changed too much, reached a value as high as 9.0, which inhibited the further growth. This is because the potassium acetate was used as carbon source, with the consumption of acetate, the left potassium ion increased pH. The future experiment will be conducted in the fermentor, and the pH will be adjusted by feeding acetic acid.
Problems encountered
No problem encountered yet.
WSU Bioprocessing and Bioproduct Laboratory 1