Physical Pretreatment Methods for Improving Microalgae Anaerobic Biodegradability
- 284 Downloads
Microalgae may be a potential feedstock for biogas production through anaerobic digestion. However, this process is limited by the hydrolytic stage, due to the complex and resistant microalgae cell wall components. This fact hinders biomass conversion into biogas, demanding the application of pretreatment techniques for inducing cell damage and/or lysis and organic matter solubilisation. In this study, sonication, thermal, ultrasound, homogeneizer, hydrothermal and steam explosion pretreatments were evaluated in different conditions for comparing their effects on anaerobic digestion performance in batch reactors. The results showed that the highest biomass solubilisation values were reached for steam explosion (65–73%) and ultrasound (33–57%). In fact, only applied energies higher than 220 W or temperatures higher than 80 °C induced cell wall lysis in C. sorokiniana. Nonetheless, the highest methane yields were not correlated to biogas production. Thermal hydrolysis and steam explosion showed lower methane yields in respect to non-pretreated biomass, suggesting the presence of toxic compounds that inhibited the biological process. Accordingly, these pretreatment techniques led to a negative energy balance. The best pretreatment method among the ones evaluated was thermal pretreatment, with four times more energy produced that demanded.
KeywordsAlgae Anaerobic digestion BMP test Bioenergy Biogas Modelling
The authors want to thank Pontificie Universidad Católica de Valparaiso for the financial support. Olivia Córdova appreciates her scholarship funded by the CONICYT, Beca Nacional Doctorado. 21121012.
Compliance with Ethical Standards
Conflict of Interest
The authors declare that they have no conflict of interest.
- 3.Bohutskyi, P., & Bouwer, E. (2013). Biogas production from algae and cyanobacteria through anaerobic digestion: a review, analysis, and research needs. In W. J. Lee (Ed.), Advanced biofuels and bioproducts (pp. 873–975). New York, NY: Springer New York. https://doi.org/10.1007/978-1-4614-3348-4_36.CrossRefGoogle Scholar
- 4.Carrere, H., Antonopoulou, G., Affes, R., Passos, F., Battimelli, A., Lyberatos, G., & Ferrer, I. (2016). Review of feedstock pretreatment strategies for improved anaerobic digestion: from lab-scale research to full-scale application. Bioresource Technology, 199, 386–397. https://doi.org/10.1016/j.biortech.2015.09.007.CrossRefGoogle Scholar
- 5.Ometto, F., Quiroga, G., Psenicka, P., Whitton, R., Jefferson, B., & Villa, R. (2014). Impacts of microalgae pre-treatments for improved anaerobic digestion: thermal treatment, thermal hydrolysis, ultrasound and enzymatic hydrolysis. Water Research, 65, 350–361. https://doi.org/10.1016/j.watres.2014.07.040.CrossRefGoogle Scholar
- 7.De Oliveira, M. A. C. L., Monteiro, M. P. C., Robbs, P. G., & Leite, S. G. F. (1999). Growth and chemical composition of Spirulina maxima and Spirulina platensis biomass at different temperatures. Aquaculture International, 7(4), 261–275. https://doi.org/10.1023/A:1009233230706.CrossRefGoogle Scholar
- 11.Sato, M., Murata, Y., Mizusawa, M., Iwahashi, H., & Oka, S. (2004). A simple and rapid dual-fluorescence viability assay for microalgae. Microbiol Cult Coll, 20(2), 53–59 Retrieved from http://www.jscc-home.jp/journal/No20_2/No20_2_53.pdf.Google Scholar
- 12.Angelidaki, I., Alves, M., Bolzonella, D., Borzacconi, L., Campos, J. L., Guwy, A. J., et al. (2009). Defining the biomethane potential (BMP) of solid organic wastes and energy crops: a proposed protocol for batch assays. Water Science and Technology, 59(5), 927–934. https://doi.org/10.2166/wst.2009.040.CrossRefGoogle Scholar
- 15.Doncaster, C. P., & Davey, A. J. H. (2007). Analysis of variance and covariance: How to choose and construct models for the life sciences. Analysis of Variance and Covariance: How to Choose and Construct Models for the Life Sciences. doi: https://doi.org/10.1017/CBO9780511611377.
- 16.APHA-AWWA-WPCF. (1999). Standard Methods for the Examination of Water and Wastewater. (20th ed.)Washington.Google Scholar
- 17.Safi, C., Charton, M., Pignolet, O., Silvestre, F., Vaca-Garcia, C., & Pontalier, P. Y. (2013). Influence of microalgae cell wall characteristics on protein extractability and determination of nitrogen-to-protein conversion factors. Journal of Applied Phycology, 25(2), 523–529. https://doi.org/10.1007/s10811-012-9886-1.CrossRefGoogle Scholar
- 18.Dubois, M., Gilles, K., Hamilton, J. K., Rebers, P. A., & Smith, F. (1951). A colorimetric method for the determination of sugars. Nature, 168(4265), 167. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/14875032.
- 23.Jankowska, E., Sahu, A. K., & Oleskowicz-Popiel, P. (2017). Biogas from microalgae: review on microalgae’s cultivation, harvesting and pretreatment for anaerobic digestion. Renewable and Sustainable Energy Reviews, 75(September), 692–709. https://doi.org/10.1016/j.rser.2016.11.045.CrossRefGoogle Scholar