Method for soil remediation and engineering

Abstract

An electrokinetic method for groundwater protection, soil remediation and engineering which comprises applying an electric field across an area of soil, sediment or slurry so as to generate a pH and Eh gradient and thereby promote the in situ precipitation of a stable iron-rich band. The method may be performed for the purpose of stabilisation and/or strategic dewatering/rewatering of soils, sediment and/or slurries, the improvement of the physical properties of soils and sediments for engineering purposes, the forced and directed migration of contaminated leachates, and/or electro-osmotic purging of non-polar contaminants.

1 . An electrokinetic method for groundwater protection, soil remediation and/or soil engineering which comprises applying an electric field between iron-rich sacrificial electrodes, which are implanted in an area of water-bearing soil, sediment or slurry so as to generate an abrupt pH and Eh gradient from acid to alkaline conditions, with the spontaneous in situ precipitation of a stable iron-rich band occurring at the boundary between the acid and alkaline zones.  
   
   
       2 . A method as claimed in  claim 1 , wherein the pH gradient is from pH2 to pH3.  
   
   
       3 . A method as claimed in  claim 1 , wherein the current is applied between one or more pairs of electrodes inserted in the area of soil, sediment or slurry.  
   
   
       4 . A method as claimed in  claim 3 , wherein the electrodes are made of cast iron, scrap iron, stainless steel or other iron-rich material.  
   
   
       5 . A method as claimed in  claim 3 , wherein the voltage employed is less than 0.5 volts per cm of the distance between a pair of electrodes.  
   
   
       6 . A method as claimed in  claim 1 , wherein the soil, sediment or slurry contains organic, inorganic and/or radioactive contaminants.  
   
   
       7 . A method as claimed in  claim 1 , wherein the iron-rich band acts as a physical and/or chemical barrier to contaminants present in the soil, sediment or slurry.  
   
   
       8 . A method as claimed in  claim 1 , where iron is precipitated to form an impermeable coherent band, or a coating which cements soil/sediment particles, or a dispersed coating on mineral grains, between two or more electrodes.  
   
   
       9 . A method as claimed in  claim 1 , wherein the generation of the pH/Eh gradient mobilises, remobilises and/or traps contaminants present in the soil, sediment or slurry.  
   
   
       10 . A method as claimed in  claim 1 , which is performed for the purpose of the stabilisation and/or strategic dewatering/rewatering of soils, sediment and/or slurries, the improvement of the physical properties of soils and sediments for engineering purposes, the forced and directed migration of contaminated leachates, and/or electro-osmotic purging of non-polar contaminants.  
   
   
       11 . A method as claimed in  claim 2 , wherein the current is applied between one or more pairs of electrodes inserted in the area of soil, sediment or slurry.  
   
   
       12 . A method as claimed in  claim 4 , wherein the voltage employed is less than 0.5 volts per cm of the distance between a pair of electrodes.  
   
   
       13 . A method as claimed in  claim 2 , wherein the soil, sediment or slurry contains organic, inorganic and/or radioactive contaminants.  
   
   
       14 . A method as claimed in  claim 3 , wherein the soil, sediment or slurry contains organic, inorganic and/or radioactive contaminants.  
   
   
       15 . A method as claimed in  claim 4 , wherein the soil, sediment or slurry contains organic, inorganic and/or radioactive contaminants.  
   
   
       16 . A method as claimed in  claim 2 , which is performed for the purpose of the stabilisation and/or strategic dewatering/rewatering of soils, sediment and/or slurries, the improvement of the physical properties of soils and sediments for engineering purposes, the forced and directed migration of contaminated leachates, and/or electro-osmotic purging of non-polar contaminants.  
   
   
       17 . A method as claimed in  claim 3 , which is performed for the purpose of the stabilisation and/or strategic dewatering/rewatering of soils, sediment and/or slurries, the improvement of the physical properties of soils and sediments for engineering purposes, the forced and directed migration of contaminated leachates, and/or electro-osmotic purging of non-polar contaminants.  
   
   
       18 . A method as claimed in  claim 4 , which is performed for the purpose of the stabilisation and/or strategic dewatering/rewatering of soils, sediment and/or slurries, the improvement of the physical properties of soils and sediments for engineering purposes, the forced and directed migration of contaminated leachates, and/or electro-osmotic purging of non-polar contaminants.  
   
   
       19 . A method as claimed in  claim 5 , which is performed for the purpose of the stabilisation and/or strategic dewatering/rewatering of soils, sediment and/or slurries, the improvement of the physical properties of soils and sediments for engineering purposes, the forced and directed migration of contaminated leachates, and/or electro-osmotic purging of non-polar contaminants.  
   
   
       20 . A method as claimed in  claim 6 , which is performed for the purpose of the stabilisation and/or strategic dewatering/rewatering of soils, sediment and/or slurries, the improvement of the physical properties of soils and sediments for engineering purposes, the forced and directed migration of contaminated leachates, and/or electro-osmotic purging of non-polar contaminants.