Abstract: A porous particulate material for treating a fluid containing a contaminant is disclosed. The particulate material comprises a cementitious matrix or binder and treated bauxite refinery residue or red mud. At least a portion of the pores in the particulate material is open cell or interconnected pores. The invention also relates to the use of a reactive permeable barrier comprising porous material, for treating a contaminated fluid. Also disclosed is a method for producing porous particulate material for treating a contaminated fluid and a method for treating a contaminated fluid, in which the porous material is used. The invention furthermore relates to a cementitious composition comprising partially neutralised red mud and cement, wherein the partially neutralised red mud has been pre-treated by contacting it with water having a total hardness supplied by calcium, magnesium or a combination thereof, of at least 3.5 millimoles per litre calcium carbonate equivalent.

Abstract: The invention provides compositions comprising bauxite refinery residues that have been reacted with sufficient calcium and magnesium ions that they have a reaction pH of less than 10.5, and one or more water treating additives. The invention also provides processes for treatment of water containing dissolved inorganic substances involving stepwise treatment of the water in which the reacted bauxite refinery residues are added after the addition of a pH-raising additive. The invention also provides processes for treatment of water containing dissolved inorganic substances in which the reacted bauxite refinery residues are added stepwise, with one or more water treating additives also being added in at least one of the steps.

Abstract: A process for the treatment of a waste material containing species having a high alkalinity and/or pH is disclosed. The process comprises the steps of contacting the waste material with a first treatment material such as sea water concentrated by evaporation. The amount of the first treatment material is sufficient to cause at least some of the alkaline species to be inactivated, thereby resulting in a treated waste material. The process may also include a step of separating the treated waste material into solid and liquid phases and then contacting the liquid phase with a sufficient amount of a second treatment material having a low pH, so as to cause at least one of the pH and alkalinity of the liquid phase to be reduced to an environmentally acceptable level.

Abstract: The invention provides compositions comprising bauxite refinery residues that have been reacted with sufficient calcium and magnesium ions that they have a reaction pH of less than 10.5, and one or more water treating additives. The invention also provides processes for treatment of water containing dissolved inorganic substances involving stepwise treatment of the water in which the reacted bauxite refinery residues are added after the addition of a pH-raising additive. The invention also provides processes for treatment of water containing dissolved inorganic substances in which the reacted bauxite refinery residues are added stepwise, with one or more water treating additives also being added in at least one of the steps.