Joseph E. Weaver
Abstract (shortened)
Biodegradable plastics are increasingly available and there is interest in their anaerobic biodegradability. As biodegradable plastics used in non-durable products become more prevalent in the marketplace, it is reasonable to expect that a growing portion will be disposed of in landfills. As such, it is desirable to characterize their degradability in an anaerobic ecosystem representative of a landfill.
Tests of anaerobic biodegradability are easier to perform if there is flexibility regarding the source of inoculum. However, the effect of the source of inoculum on test results should be characterized. The goal of this research was to determine if inocula from various sources significantly affected test results.
Four series of reactors were inoculated with either decomposed municipal solid waste (MSW), landfill leachate, anaerobically digested municipal wastewater treatment sludge (i.e., biosolids), or a digestate produced in a lab-scale anaerobic digester fed with the organic fraction of municipal solid waste. Substrates tested were copy paper, newspaper, grass, and one of a number of plastics that were thought to be biodegradable. The reactors were operated to represent optimum conditions for anaerobic biodegradation in a high solids matrix, such as a landfill. Methane production was used to measure biodegradation. Methane yields from copy paper and grass were insensitive to inoculum source (p>0.05). Newspaper methane yields and rates were sensitive to inoculum source (p<=0.05). None of the tested plastics were shown to biodegrade.
The sensitivity of newspaper to inoculum source suggests that the same inoculum for all substrates should be used in a given study if newspaper is chosen as a reference. If flexibility in inoculum source is required, then copy paper inoculated with either MSW or digestate is recommended. In addition to flexibility, the digestate and MSW inocula produced the most reproducible results for methane yield and production rate, respectively.
Biblographic Info
(2013) Weaver, JE, “Effect of Inoculum Source on the Rate and Extent of Anaerobic Biodegradation” Under the direction of Barlaz, MA and de los Reyes III, FL. MS Thesis, North Carolina State University, Raleigh, NC. [bib]