Method and apparatus for separation of a substance from groundwater

A system for separating an amount of a substance from groundwater that is present in a body of ground, the system comprising:

• an elongate chamber defined by an outer wall wherein, in use, the chamber is at least partially located in the ground, with an interior of the chamber being in fluid communication with the groundwater in the ground via openings in the outer wall which are arranged to exclude sediment and solid ground matter from accessing the chamber during movement of the groundwater thereinto;
• a gas introduction device arranged at the interior of the chamber wherein, in use, an upward flow of an introduced gas is placed in fluid communication with groundwater located in the chamber, thereby inducing an upward flow of said groundwater within the chamber and producing a froth layer which is formed at, and rises above, an interface with the flow of groundwater and the flow of introduced gas, the froth layer including groundwater and a concentrated amount of the substance compared with its initial concentration in the groundwater entering the chamber;
• a froth depth regulation device positioned above the interface and arranged in use to control the groundwater content of the froth layer which rises above the interface, to influence the concentration of the substance therein, wherein said froth depth regulation device maintains the depth of the froth above the interface by being moveably vertically positionable within the chamber in response to movement of the location of the interface in use, said froth depth regulation device being arranged for confining the cross-sectional flow path of the froth in the chamber, resulting in drainage of said froth layer;
• and
• a froth layer removal device positioned at an upper end of the chamber and arranged in use for removal of at least some of the froth layer from the chamber, once said drainage has occurred.