Optimization of washing rate in a hybrid recycling system of solid state and submerged fermentation

World J Microbiol Biotechnol

Osa

et al. 2007

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Long term fed-batch composting experiments were conducted for 200 days using two types of bulking agents; woodchip and PET flake, with periodic compost withdrawal through a washing process. The bacterial communities of composting materials in the two different bulking agents were also investigated by 16S rRNA gene clone analysis. The decomposition rate in both composting reactors was 86.1% and 88.2% of the total organic load, respectively. The control experiment of dead-end operation without compost withdrawal by washing process could not be maintained for more than 102 days because of its low performance. The reactor with compost withdrawal, however, improved the decomposition rate in the composting process, and could be applied in the long run. There was a significant difference in the bacterial community between the FBC reactor with woodchip and another with PET flake as the bulking agent though the decomposition rates were similar. The reactor with woodchip as the bulking agent consisted of 95% Bacillales while the PET flake reactor contained 54% of total bacteria count. In addition, Lactobacillales was dominant at 38% in the PET flake reactor and the bacterial community in general significantly differed from the woodchip reactor. Furthermore, there was a difference in the species composition in the Bacillales and the bacterial community showed a significant difference at the species level between the two reactors. Although bacterial community differed, the decomposition rates between the two reactors were similar and PET flake showed greater viability than woodchip as a bulking agent due to its high abrasion resistance and non-biodegradability.

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Section: Resultssupporting

confidence: 91%

Section: Fed-batch Composting Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Bacterial community and decomposition rate in long term fed-batch composting using woodchip and Polyethylene terephthalate (PET) as bulking agents

World J Microbiol Biotechnol

Osa

et al. 2007

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“…Moreover, some trouble is possible in a composting process, for example, aggregation of contents, decreasing pH and decomposing rate (Nagao et al 2005). Since the appearance of some microorganisms might reflect these troubles, an understanding of the microbial community is important to effectively manage of the composting process, especially in the start-up period.…”

Section: Introductionmentioning

confidence: 99%

The dominant bacteria shifted from the order “Lactobacillales” to Bacillales and Actinomycetales during a start-up period of large-scale, completely-mixed composting reactor using plastic bottle flakes as bulking agent

World J Microbiol Biotechnol

Toda

et al. 2009

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Bacterial community succession in the start-up of a large-scale, completely-mixed composting reactor was analyzed by 16S rRNA gene (16S rDNA) clone analysis and denaturing gradient gel electrophoresis (DGGE) combined with measurements of temperature, pH, moisture contents, and decomposing rate. DGGE analysis and physicochemical parameters showed that bacterial community succession occurred in four phases; (1) at the start of operation and pH decreasing period (day 0-3), (2) pH decreased and increased period (day 4-11), (3) middle term, moisture content decreasing and maximum temperature increased period (day 12-16) and (4) latter term, temperature decreasing period (day 17-24). Lactobacillus spp. and Bacillus coagulans were detected from the initial phase and middle term, respectively. 16S rDNA clone analysis showed that the dominant bacteria shifted from the order ''Lactobacillales'' to Bacillales and Actinomycetales. The order ''Lactobacillales'' was unique which may be caused by using the plastic bottle flakes (polyethylene terephthalate, PET) as bulking agent.

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Bacterial Communities in Various Conditions of the Composting Reactor Revealed by 16S rDNA Clone Analysis and DGGE

Sustainable Biotechnology

Toda

et al. 2009