Correlation between system performance and bacterial composition under varied mixing intensity in thermophilic anaerobic digestion of food waste
KAUST DepartmentBiological and Environmental Sciences and Engineering (BESE) Division
Environmental Science and Engineering Program
Water Desalination and Reuse Research Center (WDRC)
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AbstractThis study examines the stability and efficiency of thermophilic anaerobic digesters treating food waste under various mixing velocities (50–160 rpm). The results showed that high velocities (120 and 160 rpm) were harmful to the digestion process with 18–30% reduction in methane generation and 1.8 to 3.8 times increase in volatile fatty acids (VFA) concentrations, compared to mild mixing (50 and 80 rpm). Also, the removal rate of soluble COD dropped from 75 to 85% (at 50–80 rpm) to 20–59% (at 120–160 rpm). Similarly, interrupted mixing caused adverse impacts and led to near-failure conditions with excessive VFA accumulation (15.6 g l), negative removal rate of soluble COD and low methane generation (132 ml gVS). The best efficiency and stability were achieved under mild mixing (50 and 80 rpm). In particular, the 50 rpm stirring speed resulted in the highest methane generation (573 ml gVS). High-throughput sequencing of 16S rRNA genes revealed that the digesters were dominated by one bacterial genus (Petrotoga; phylym Thermotogae) at all mixing velocities except at 0 rpm, where the community was dominated by one bacterial genus (Anaerobaculum; phylum Synergistetes). The Petrotoga genus seems to have played a major role in the degradation of organic matter.
CitationGhanimeh SA, Al-Sanioura DN, Saikaly PE, El-Fadel M (2018) Correlation between system performance and bacterial composition under varied mixing intensity in thermophilic anaerobic digestion of food waste. Journal of Environmental Management 206: 472–481. Available: http://dx.doi.org/10.1016/j.jenvman.2017.10.062.
SponsorsThis research was supported by the National Council for Scientific Research of Lebanon (CNRS Grant number 02-11-12) and the American University of Beirut (AUB). Special thanks are extended to the US Agency for International Development for its support to AUB in acquiring the equipment used in the experimental program which was carried out at AUB laboratories. The microbial analysis was conducted at KAUST.