Systems, methods and treatment cells for rehabilitating and valorizing a soil

Abstract

The present invention generally pertains to treatment cells, systems and methods for rehabilitating and valorizing a soil. More specifically, the present invention relates to methods for removing volatile compounds from the contaminated soils. The methods and system generally make use of an openable and reclosable rigid enclosure capable of receiving and treating many tons of soils. According to the invention, heated air is circulated through the soil to allow volatilization of the contaminants which can then be captured and separated form the circulating air before the air is re-heated and re-circulated through the soil.

1 - 33 . (canceled) 
     
     
         34 . A method for removing an unwanted volatile compound from a heap of soil comprising the steps of:
 a) placing said heap of said soil into a treatment cell adapted for receiving said heap of soil, wherein said treatment cell is rigid and heat-resistant and is adapted for operation at a temperature of at least 150° C. and also adapted for operation at a negative pressure;   b) circulating under negative pressure conditions a volume of heated air through the heap of soil placed into the treatment cell in order to create a vacuum on top of said heap of soil and to gradually increase the temperature of the heap of soil until it reaches a temperature sufficient to allow volatilization out from the soil of at least a portion of the volatile compound;   c) collecting heated air of step (b) comprising a volatile compound volatilized therein;   d) separating at least a portion of said volatilized compound from said air;   e) re-heating air of step (d); and   f) introducing the re-heated air of step (e) under negative pressure into the treatment cell for re-circulation through said heap of soil.   
     
     
         35 . The method of  claim 34 , wherein step (f) comprises cooling and condensing into liquid vapor contained in the collected heated air. 
     
     
         36 . The method of  claim 34 , wherein steps (b) to (f) are repeated until said heap of soil is relatively exempt from said volatile compound. 
     
     
         37 . The method of  claim 34 , wherein steps (b) to (f) are repeated until humidity in the soil is about 1% to about 3%. 
     
     
         38 . The method of  claim 34 , further comprising step (g) of removing from the heap of soil fine particles comprising heavy metals. 
     
     
         39 . The method of  claim 38 , wherein removing said fine particles comprises passing the heap of soil through screening means. 
     
     
         40 . The method of  claim 34 , wherein said heap of soil comprises at least one of contaminated soil, wet soil, sludges, gravel and sand. 
     
     
         41 . The method of  claim 34 , wherein the volatile compound is water or a hydrocarbon contaminant. 
     
     
         42 . The method of  claim 41 , wherein the hydrocarbon contaminant is selected from the group consisting of gasoline, diesel, jet fuel, heating fuel, liquefied petroleum gas, oils, petroleum derivatives and mixtures thereof. 
     
     
         43 . The method of  claim 34 , wherein the treatment cell is adapted for operation at a negative pressure reaching at least 700 mm Hg (700 Torr). 
     
     
         44 . The method of  claim 34 , wherein the air is circulated and re-circulated in a closed loop mode in order to minimize leaks of air and contaminants into the environment. 
     
     
         45 . The method of  claim 34 , wherein the treatment cell comprises:
 an openable and reclosable rigid and heat-resistant enclosure adapted for receiving said heap of soil, wherein the enclosure is adapted for operation at a temperature of at least 150° C., and is adapted for operation at a negative pressure reaching at least 700 mm Hg (700 Torr); and   an air intake and an air exhaust operatively connected to said enclosure, the air intake and the air exhaust being configured and positioned to input and output the hot air, respectively, under the negative pressure conditions,
 wherein the air exhaust comprises a plurality of perforated collection pipes configured to spread over an upper portion of the enclosure and above the soil when the soil is placed in the enclosure, 
 wherein said air intake comprises a plurality of perforated distribution pipes configured to spread over a bottom portion of the enclosure and under the soil when the soil is placed in the enclosure; and 
   wherein the enclosure, the air intake, and the air exhaust are substantially air-tight in order to reach a negative pressure of at least 700 mm Hg (700 Torr) in the treatment cell when the air intake and the air exhaust are operatively connected to at least one vacuum pump.   
     
     
         46 . A method for removing an unwanted volatile compound from a heap of soil comprising the steps of:
 a) placing said heap of soil within a treatment cell comprising:
 an openable and reclosable rigid and heat-resistant enclosure adapted for receiving said heap of soil, wherein the enclosure is adapted for operation at a temperature of at least 150° C., and is adapted for operation at a negative pressure reaching at least 700 mm Hg (700 Torr); and 
 an air intake and an air exhaust operatively connected to said enclosure, the air intake and the air exhaust being configured and positioned to input and output hot air, respectively, under the negative pressure conditions,
 wherein the air exhaust comprises a plurality of perforated collection pipes configured to spread over an upper portion of the enclosure and above the soil when the soil is placed in the enclosure, 
 wherein said air intake comprises a plurality of perforated distribution pipes configured to spread over a bottom portion of the enclosure and under the soil when the soil is placed in the enclosure; and 
 
   wherein the enclosure, the air intake, and the air exhaust are substantially air-tight in order to reach a negative pressure of at least 700 mm Hg (700 Torr) in the treatment cell when the air intake and the air exhaust are operatively connected to at least one vacuum pump; and   b) circulating heated air through said heap of soil while creating a negative pressure throughout an interior of said treatment cell to gradually increase the temperature of the soil to a temperature allowing volatilization out from the soil of at least a portion of said volatile compound.   
     
     
         47 . The method of  claim 46 , further comprising step (c) of removing fine particles comprising heavy metals. 
     
     
         48 . The method of  claim 46 , wherein the heated air is introduced into said enclosure at a temperature of about 150° C. to about 200° C. 
     
     
         49 . The method of  claim 46 , wherein soil temperature is maintained at a temperature ranging from about 60° C. to about 130° C. 
     
     
         50 . The method of  claim 46 , further comprising the steps of collecting air having circulated through said heap of soil and removing therefrom said volatilized compound. 
     
     
         51 . The method of  claim 46 , further comprising the steps of re-heating air collected and recirculating said reheated air through said heap of soil. 
     
     
         52 . The method of  claim 46 , wherein the volatile compound is water or a hydrocarbon contaminant. 
     
     
         53 . The method of  claim 52 , wherein the hydrocarbon contaminant is selected from the group consisting of gasoline, diesel, jet fuel, heating fuel, liquefied petroleum gas, oils, and petroleum derivatives. 
     
     
         54 . The method of  claim 46 , wherein said heap of soil comprises at least one of contaminated soil, wet soil, sludges, gravel and sand.