Study of alternatives for the design of a mobile unit for wastewater treatment by supercritical water oxidation

Supercritical water oxidation (SCWO) has been shown to be an appropriate te chnology for the treatment of water containing toxic and hazardous substanc es, because it provides high destruction efficiencies. This paper reports a study of alternatives, and optimisation of various parameters and conditio ns, which are applied to the design of a mobile treatment unit. Phenol was selected as a model organic compound present in the feed stream and NaCl wa s selected as a model polar compound for solid separation. Pilot plant resu lts show that efficiencies above 99.9% in phenol destruction are reached, a t an operation temperature of about 650 degreesC, with stoichiometric amoun ts of air. Feed streams with a wide range of heating values (lower limit 53 0 and upper limit 930kJkg(-1)) can be handled, because these values allow b oth thermal and mechanical energy recoveries, which are the key factor for economic feasibility. The unit is capable of handling wastewater containing toxic, recalcitrant or nonbiodegradable compounds that cannot be treated w ith global streams at the wastewater treatment plant of a factory. It is sp ecifically proposed for use in industries in which wastewater contains solv ent mixtures of fine chemicals and pharmaceuticals. (C) 2001 Society of Che mical Industry.