Abstract: A process for treating sulphate containing effluent, which includes receiving a sulphide containing effluent into a two-phase fluidised bed reactor containing particles and floating media, permitting calcium carbonate from the effluent to precipitate on particles in the first fluidised bed reactor, aerating the solution in the reactor to remove CO2 from the solution, thereby to increase the pH in the reactor, permitting biological sulphide oxidation to occur on the floating media by means of sulphide oxidizing bacteria thereby to produce elemental sulphur, recycling the fluidised bed reactor at a sufficient rate to effect abrasion to remove elemental sulphur from the floating media, harvesting the sulphur from a top portion of the reactor, recycling hydroxyl ions internally in solution in to enhance calcium carbonate precipitation by further increasing the pH.

Abstract: A process for treating sulphide-containing water includes maintaining a steep redox potential gradient in an interface zone of the sulphide-containing water. The water is exposed to an oxygen-containing environment, and the interface zone is located immediately below the surface of the water. Sulphide in the water is biologically oxidized, in the interface zone, to sulphur. The sulphur may be removed by settling, thereby achieving a final removal of sulphur compounds.

Abstract: A process for treating which contains carbonaceous solids, includes subjecting the water to hydrolysis in a biological hydrolysis reaction stage, in the presence of sulfate ions, thereby to produce treated water, a slurry component, and a sulfur-containing component. Treated water, the slurry component, and the sulfur-containing component are withdrawn from the reaction stage.

Abstract: A process for treating sulphate-containing waste water comprises introducing a feedstock comprising sulphate-containing waste water, into a pond. The sulphate-containing waste water is subjected to biological sulphate reduction in the pond, thereby to convert dissolved sulphate anions to dissolved sulphide anions. Treated waste water, containing the dissolved sulphide anions, is withdrawn from the pond.

Abstract: A process for treating sulphate- and metal-containing waste water, includes subjecting, in a reaction stage, the sulphate- and metal-containing waste water to biological sulphate reduction in which sulphates in the waste water are converted to sulphides, with metals present in the waste water precipitating out and treated waste water being obtained. The precipitated metals are withdrawn from the reaction stage, while treated waste water is withdrawn from the reaction stage. The treated waste water is subjected to polishing and/or to nutrient removal.

Abstract: A process for treating metal-containing acid water comprises adding an alkaline aqueous component to metal-containing acid water, thereby to raise the pH of the acid water and to cause metals therein to precipitate. The precipitated metals are separated from the water in a separation stage. The water is then passed to a biological alkalinity generating stage wherein the alkalinity of the water is increased biologically. The alkaline aqueous component, which is added to the metal-containing acid water, is withdrawn from the alkalinity generating stage. Treated water is also withdrawn from the alkalinity generating stage.

Abstract: A process for treating sulphate- and metal-containing waste water comprises adding a sulphide compound to the waste water. The sulphide compound reacts with a metal in the waste water to form a corresponding metal sulphide, which precipitates from the waste water. The precipitated metal sulphide is separated from the waste water, to obtain sulphate-containing waste water, which is subjected to biological sulphate reduction in which sulphates in the waste water are converted to sulphides.

Abstract: A process for treating acid water process comprises raising the alkalinity of an aqueous component by means of algae, and separating algae from the aqueous component, thereby to obtain a purified alkaline aqueous component. The purified alkaline aqueous component is added to acid water, thereby raising the pH of the acid water.

Abstract: A method of separating particulate material suspended in a liquid from that liquid is described. The method includes the steps of: providing at least one upright tubular filter unit having a top end and a lower end; introducing a flow of the suspension into the tubular filter unit at one end thereof; and allowing the suspension to pass through the tubular filter unit trapping particulate material on an inside surface thereof. Apparatus in which the method of the invention is performed is also described.

Abstract: A method of making a hollow fiber membrane comprises extruding a membrane-forming polymer solution through the annulus of a tube-in-orifice spinneret (12) to form a nascent hollow membrane (32), there being a lumen coagulant in the lumen of the nascent membrane, and the outside of the nascent membrane being contacted with an external coagulant (34). The external coagulant has a solvent content which is such that, at the interface between the nascent membrane and the external coagulant, liquid--liquid phase separation rather than gelation is thermodynamically the favored process, and the membrane is then subjected to a vapor-phase non-solvent environment to induce precipitation of the phase-separated polymer.

Abstract: A water purification device comprises a compartment for holding a supply of impure water; a purified water collection zone; and a dense hydrophilic membrane between the compartment and the purified water collection zone. The membrane is capable of functioning by membrane distillation. A water vapour condensing surface is provided in the purified water collection zone. The condensing surface is spaced from the membrane.

Abstract: A method of cloud seeding for precipitation enhancement comprises releasing hygroscopic seeding particles from a seeding flare 10. The particles are obtained by burning, in the flare, a pyrotechnic composition which includes, as an oxidizing agent, a compound selected from the group consisting in potassium chlorate and potassium perchlorate. The particles are allowed to enter a suitable cloud formation. The particles act as seeds or nuclei for precipitable water drop formation, thereby to enhance precipitation from the cloud formation.

Abstract: A method of preparing a semi-permeable membrane suitable for reverse osmosis includes contacting a porous artifact with an hydrated metal oxide, to form an hydrated metal oxie coated artifact. Thereafter the hydrated metal oxide coated artifact is contacted with at least one polyelectrolyte selected from the group listed in claim 1, thereby to form a polyelectrolyte layer in or on the hydrated metal oxide layer.

Abstract: In a slurry dewatering process, slurry is pumped into a porous tube at a sufficiently low velocity for laminar flow conditions to exist. The pressure is sufficiently high for liquid in the slurry to permeate outwardly through the tube wall and for solids in the slurry to be deposited in the form of an annular cake on the tube wall. The deposition of solids is controlled so that the cake thickness is substantially uniform throughout. When a predetermined thickness of cake has been deposited, the pressure inside the tube is decreased and the flow velocity is increased and the cake is dislodged from the tube wall in flake form and is conveyed downstream for collection on a screen or the like.

Abstract: A method of treating an organic material such as textile fibres with an alkali metal hydroxide solution including the steps of:(i) contacting the organic material with the hydroxide solution to produce an effluent comprising an alkali metal hydroxide solution which contains multivalent ions and soluble and insoluble organic and inorganic matter;(ii) reducing the pH of the effluent to a value in the range 7 to 9 by contacting it with an acid gas;(iii) filtering the solution from step (ii) to remove suspended insoluble matter having a size greater than 0,1 microns.