(423g) Environmental Implications of Phenol Gasification in Supercritical Water

Supercritical water gasification (SCWG) has been proposed as both a wastewater treatment technology and a biomass conversion technology. Phenol is an important candidate for study in either case, because it is both a regulated EPA priority pollutant commonly found in industrial wastewater effluents and a good model compound for the phenolic structures found in biomass. Additionally, several investigations of SCWG using whole biomass feedstocks identified phenol as a persistent byproduct. Regardless of whether phenol is considered a wastewater pollutant or a byproduct from biomass gasification, our own experiments show that phenol leads to the formation of little gas and a swath of heavier molecular weight compounds when exposed to supercritical water. Most of the non-gaseous products identified in these experiments are polycyclic aromatic hydrocarbons (PAHs), EPA priority pollutants, or have known human health and environmental effects. We experimentally quantified as many of these compounds as possible under various SCWG processing conditions. We then used this experimental data in conjunction with the UNEP/SETAC environmental toxicity (“USEtox”) model and other models to characterize the human and ecotoxic impacts due to hypothetical emissions of phenol SCWG byproduct streams into freshwater.