Final Report - Ohio Department of Transportation

One task of the research project was to generate a sufficient volume of yard-waste-derived
bitumen to support future physical characterizations studies. This has been accomplished. The
carbonization efforts described here resulted in approximately 3 liters of bio-oil and bitumen.
One consideration that has not yet been addressed is that carbonization also yields an aqueous
byproduct. This may be released as steam, but doing so would substantially reduce the recovery
of the organic fraction, and could lead to serious air pollution control compliance issues.
Generally, it is preferable to condense the off gas into a liquid phase and then separate the
organic phase from the aqueous phase. However, as the image of Fig. 28 illustrates, there can be
a great deal of variability in the nature of the aqueous phase depending on the type of yard waste
feed stock. Table 9 presents a preliminary chemical characterization of off gas condensate. Note
that these solutions are dominated by organic acids (high COD, low pH, high % volatile solids).
Additional analysis should be conducted to determine to what extent valuable byproducts can be
extracted from this byproduct fraction, and to what extent the management of this as wastewater
will lead to additional costs.
Fig. 28 – Liquid Phase Carbonization Byproducts
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