MICROBIAL COMMUNITY PROFILING OF MUNICIPAL SOLID WASTE AT DIFFERENT STAGES OF DEGRADATION

Although anaerobic degradative processes during waste decomposition are well characterized, the microbial community profile and individual species responsible for the different stages of degradation have been minimally studied. Given the dependency of many anaerobic microorganisms on other syntrophic microorganisms and available electron acceptors, microbial diversity plays an important factor in evaluating the refuse decomposition process. Thus, the assessment of microbial diversity is one of the first steps towards understanding species-specific metabolic properties that contribute to overall refuse decomposition. Another consideration is the assessment of the source of microbial diversity in landfills. In previous work the population of methanogens in fresh refuse was rather low (Barlaz et al., 1989). These microorganisms are known to grow relatively slowly compared to bacteria, suggesting that fresh refuse with few methanogens may result in an environment more prone to souring until a sufficient methanogen population is established.

Bacterial community profiles exhibited seasonal differences in fresh refuse collected at different times of the year as assessed by terminal restriction fragment polymorphism (T-RFLP). T-RFLP profiles in decomposed refuse showed large shifts, indicating the the majority of the microbial community was replaced as decomposition proceeded from the accelerated methane phase to the well-decomposed phase. A comparison of the solid fraction of MSW versus leachate showed that bacterial profiles are more similar as refuse is degraded. Nevertheless, large differences between the solid fraction and leachate were found in all instances, indicating that both must be considered when evaluating a landfill microbial community.



Copyright: © IWWG International Waste Working Group
Source: Specialized Session F (Oktober 2007)
Pages: 10
Price: € 10,00
Autor: Bryan Fleet Staley
Prof. Morton A. Barlaz
Dr. Francis Lajara De los Reyes
J.C. Ellis

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