Feasibility of Supercritical Water Treatment on the Detoxification of Medical Waste Incinerator Fly Ash

摘要

Fly ash from medical waste (MW) incinerator contains organic pollutants and toxic heavy metals. This special type of ash is classified as hazardous waste that must be properly treated. In this work, two types of MW incinerator fly ashes from different incinerators were employed. Supercritical water (SCW) and supercritical water + H2O2 (SCWH) treatments were conducted on the ashes. The results showed that SCW treatment could change heavy metals from soluble fraction into organic-bounded and residual fractions, while SCWH treatment could further change the organic-bounded fraction into residue fraction. However, it was observed that arsenic species were strongly affected by solution pH under SCW condition. After 1h SCWH treatment, the leachability of hazardous metals from the ashes was significantly reduced below the limits of USEPA. Accordingly, it is believed that SCWH is an effective process for MW fly ash detoxification.