Removal and Destruction of Organic Compounds in Water Using Adsorption, Steam Regeneration, and Photocatalytic Oxidation Processes

Abstract

A treatment strategy is examined whereby organic compounds in the aqueous phase are first removed by fixed-bed adsorption, followed by off-line regeneration of spent adsorbent using saturated steam (160°C) and cleanup of steam condensate using fixed-bed photocatalysis. This treatment strategy is examined with the following organic compounds: Tetrachloroethylene (PCE), carbon tetrachloride (CCl4), p-dichlorobenzene (p-DCB), o-chlorobiphenyl (o-PCB), and methyl ethyl ketone (MEK). For six cycles of adsorption and regeneration, the steaming process is effective to regenerate the adsorbent exhausted with PCE, p-DCB, CCl4, or MEK. In the case of o-PCB, there is about 20% loss in adsorbent capacity after the first cycle; however, the adsorption capacity for Cycles 2–6 is almost the same. Fixed-bed photocatalysis is examined for decontamination of steam condensate carrying the desorbed organics, and it is observed to be effective for mineralization of aqueous phase PCE, p-DCB, CCl4, and o-PCB. In the case of MEK, although 97% of the compound was removed, only 16% removal of total organic carbon was observed, thereby suggesting that some by-products were produced that were refractory to oxidation.