Process and system for subcritical oxidation of water-borne organic contaminants

Abstract

A highly efficient and effective process for destroying organic contaminants in wastewater streams, without the need for supercritical oxidation conditions, is provided.

What is claimed is: 
     
         1 . A system for purifying a waste stream comprised of water, at least one organic contaminant and, optionally, at least one oxidizing agent comprising:
 i) a feed line for the waste stream;   ii) a subcritical reactor vessel;   iii) a heat exchanger; and   iv) a pressure exchanger;   wherein:   a) the waste stream is provided to the reactor vessel by the feed line;   b) the waste stream, when in the reactor vessel, is in a subcritical state;   c) in the reactor vessel the at least one organic contaminant undergoes a catalyzed or uncatalyzed oxidative reaction with oxidizing agent effective to completely oxidize at least a portion of the organic contaminant, forming a purified effluent stream;   d) the heat exchanger removes heat from the purified effluent stream for use in raising the temperature of the waste stream and recovers at least 80% of heat input; and   e) the pressure exchanger removes mechanical energy from the effluent stream for use in raising the pressure of the waste stream and recovers at least 95% of such mechanical energy.   
     
     
         2 . The system of  claim 1 , wherein the waste stream comprises at least one oxidizing agent. 
     
     
         3 . The system of  claim 2 , wherein the at least one oxidizing agent includes at least one peroxide. 
     
     
         4 . The system of  claim 2 , wherein the at least one oxidizing agent includes hydrogen peroxide. 
     
     
         5 . The system of  claim 1 , wherein at least one oxidizing agent is introduced into the subcritical reactor vessel and the at least one oxidizing agent includes at least one of molecular oxygen or at least one peroxide. 
     
     
         6 . The system of  claim 1 , wherein at least one catalyst capable of catalyzing oxidation of the at least one organic contaminant is present in the subcritical reactor vessel and is contacted with the waste stream. 
     
     
         7 . The system of  claim 1 , wherein the heat exchanger recovers at least 95% of heat input. 
     
     
         8 . The system of  claim 1 , wherein the pressure exchanger recovers at least 98% of mechanical energy. 
     
     
         9 . The system of  claim 1 , wherein the pressure exchanger is a rotary pressure exchanger. 
     
     
         10 . The system of  claim 1 , wherein the heat exchanger is a plate heat exchanger or a shell and tube heat exchanger. 
     
     
         11 . The system of  claim 1 , wherein the reaction vessel is maintained at a temperature of from 200 to 350° C. and a pressure of from 500 to 3000 psig. 
     
     
         12 . The system of  claim 1 , wherein the system does not include any motorized equipment.