Abstract: Method for treatment of sludge, which includes precipitated aluminium and/or iron hydroxide, whereby the sludge first is added acid and thereafter is subjected to at least one membrane filtration process, whereby a permeate or a concentrate is obtained, including trivalent aluminium and/or iron ions in solution. The aluminium and/or iron ions in the permeate, or concentrate, are crystallised (salting out) in a precipitation.

Abstract: The present invention relates to a metal sulphate composition comprising a polynucleate metal sulphate having the general formulae [Me(OH)x(SO4)y(H2O)z]n where Me is three valence metal ion of the group aluminium and iron n is an integer x is 1.0-2.8; y is 0.1-1.0; x+2y is 3 and z is 1.5-4, z being <4 when the product is in solid form and z being >4 when the product is in solution whereby it has a content of MG2+, its pH is at least 3.3 and at most 5.0 in liquid form, it has a basicity of at most 2.8, and it contains highly charged cationic polyaluminium complexes, as well as a method for its manufacture, and its use.

Abstract: In a method of purifying an aluminium salt from a first aqueous aluminium salt solution of a raw material containing impurities, which comprise salts of at least one more noble metal than aluminium dissolved therein, a method of purifying a metal salt from inorganic impurities in an aqueous solution thereof is included. A plant for carrying out the method is also shown.

Abstract: A process for treatment of waste containing organic material, phosphorous and water in suitable amounts to be a pumpable sludge and in order to be oxidizable through supercritical water oxidation, comprises the steps of: putting the sludge into conditions being supercritical for water; adding oxidant, particularly, oxygen to the sludge, wherein the organic material contained in the waste is substantially completely oxidized by means of supercritical water oxidation; separating the phosphorous from water and from carbon dioxide formed during the oxidation; and recovering the phosphorous by means of dissolving the phosphorous in an alkali.

Abstract: The present invention relates to a metal sulphate composition comprising a polynucleate metal sulphate having the general formulae [Me(OH)x(SO4)y(H2O)z]n where Me is three valence metal ion of the group aluminium and iron n is an integer x is 1.0-2.8; y is 0.1-1.0; x+2y is 3 and z is 1.5-4, z being <4 when the product is in solid form and z being >4 when the product is in solution whereby it has a content of MG2+, its pH is at least 3.3 and at most 5.0 in liquid form, it has a basicity of at most 2.8, and it contains highly charged cationic polyaluminium complexes, as well as a method for its manufacture, and its use.

Abstract: In a method of purifying an aluminium salt from a first aqueous aluminium salt solution of a raw material containing impurities, which comprise salts of at least one more noble metal than aluminium dissolved therein, a method of purifying a metal salt from inorganic impurities in an aqueous solution thereof is included. A plant for carrying out the method is also shown.

Abstract: In a method of purifying an aqueous solution contaminated by an aluminium salt and salts of less noble metals, an alkali is first added to the aqueous solution followed by adding metallic aluminium. This results in the precipitation of aluminium as well as the less noble metals, which are subsequently removed.

Abstract: The invention relates to a process for preparing a usable product, in particular a water treatment solution which contains ferric iron, from an impure ferric sulfate solution which contains as an impurity at least one other metal, the process comprising a first precipitation step in which a base is added to the said impure ferric sulfate solution in order to raise the pH to approx. 2-5, preferably approx. 3-4, whereupon ferric hydroxide precipitates; following the first precipitation step, a second precipitation step in which there are added to the solution an oxidant and a base to raise the pH to approx. 6-10, preferably approx. 8-9, whereupon the said impurity metal precipitates; and one or more separation steps to separate from the sulfate solution the solids precipitated in the first and the second precipitation steps; as well as possibly an additional step in which the said separated solids, or a portion thereof, are treated further in order to form a usable product.

Abstract: A process for the purification of solutions containing metals comprising neutralization of the solution, reduction of Fe(III) present, and elimination of ingoing dissolved zinc, whereby the ingoing solution containing metals is neutralized using magnetite and/or metallic iron, that the ingoing iron (III) is reduced to iron (II) by means of an addition of metallic iron, that ingoing heavy metals are precipitated by the addition of a precipitating amount of a sulphide, whereby the metal sulphides precipitated are recovered by means of filtration, that the solution is, optionally, subjected to an ion exchange operation to transfer ingoing zinc into non-complex bound form, whereupon zinc is recovered as zinc carbonate, that iron (II) in the remaining solution is oxidized to iron (III), whereupon the solution is used as such or is further treated for increasing the metal content for the purpose intended.