Submitted to: Journal of Advanced Agricultural Technologies
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2018
Publication Date: 9/1/2018
Citation: Nanh Lovanh, Graciela M. L. Ruiz-Aguilar, John Loughrin. 2018. Evaluation of biochemical factors from mixed animal wastes feedstock in biogas production. Journal of Advanced Agricultural Technologies. 5(3):198-201. https://doi.org/10.18178/joaat.5.3.198-201.
Interpretive Summary: Millions of tons of animal wastes from livestock operations are generated in the U.S. each year. Animal manure has been traditionally used as natural fertilizer for crop production. However, land application of manure is limited due to problems associated with potential groundwater contamination, air quality, and limited immediate availability of agricultural land. Animal manure is a major source of anthropogenic greenhouse gas emission and offensive odors. Thus, alternative waste management and treatment are necessary. Anaerobic digestion of animal wastes can serve as an alternative waste treatment practice that could reduce air pollution and generate energy for on-farm use. However, bioenergy production from livestock wastes may be difficult since these wastes are recalcitrant to anaerobic digestion. Therefore, a thorough understanding of anaerobic digestion systems utilizing livestock wastes is needed. A study was carried out to examine the effects of various parameters relating to the operation and the optimization of bioenergy from livestock wastes. The results show that acclimated culture of bacteria is needed for optimal biogas production. Furthermore, additional carbon source, whether by mixing different feedstock, along with the correct ranges of pH and temperature help improve the biogas production. Biological inhibitor such as ammonia was also found to have a major effect on biogas production. Likewise for a flow through system, the duration of digestion time is very critical in achieving optimal biogas production. Thus, it is very important to consider various biochemical factors when designing and operating an anaerobic digester for optimizing biogas production, especially from non-traditional feedstock such as mixed livestock wastes.
Technical Abstract: Animal wastes can serve as the feedstock for biogas production (mainly methane) that could be used as alternative energy source. The green energy derived from animal wastes is considered to be carbon neutral and offsetting those generated from fossil fuels. In this study, an evaluation of methane production from animal wastes with different nitrogen and carbon sources was carried out. Anaerobic batch reactors containing different mixtures of animal wastes and potential inhibition sources were set up to evaluate methane potential. Biogas productions were sampled and monitored by gas chromatography and photoacoustic gas analyzer. The results showed that methane productions increased as the solid concentrations, temperature and total carbon increased. However, biogas production decreased substantial when ammonia concentrations in the feedstock were high. The addition of carbon to the feedstock provided a better substrate for methane production during anaerobic digestion of animal wastes. Methane productions were more than several times greater from reactors with feedstock amended with additional source of carbon than the ones with just animal wastes (e.g., swine, poultry or just dairy) or acclimated microbes. There was no methane production in the sterile control. Thus, it appears that additional carbon source is necessary to increase methane production from animal waste anaerobic digester. Inhibitor such as ammonia appears to hinder the biomethanation in the anaerobic digestion of animal wastes for optimum methane production.