A method for removing hydrogen sulfide from a biogas, wherein the hydrogen sulfide is absorbed in an aqueous liquid to produce a cleaned gas having a reduced amount of hydrogen sulfide relative to the biogas. The aqueous liquid is subsequently treated by contacting with a sulfur dye or sulfurized vat dye in the presence of an oxidizer such as oxygen gas, to convert the sulfides in the aqueous liquid to a non-toxic, water-soluble, product.

A method for removing hydrogen sulfide from a biogas, wherein the hydrogen sulfide is absorbed in an aqueous liquid to produce a cleaned gas having a reduced amount of hydrogen sulfide relative to the biogas. The aqueous liquid is subsequently treated by contacting with a sulfur dye or sulfurized vat dye in the presence of an oxidizer such as oxygen gas, to convert the sulfides in the aqueous liquid to a non-toxic, water-soluble, product.

A method for treating sulfide in an aqueous fluid comprises contacting the fluid with an oxidizer in the presence of a sulfur dye or sulfurized vat dye. In one embodiment, the method comprises treating; sulfide contaminated water by contacting the contaminated water with a gas including oxygen in the presence of a sulfur dye or a sulfurized vat dye. The method is useful for remediating industrial, agricultural, and municipal wastewater.

A method for treating sulfide in an aqueous fluid comprises contacting the fluid with an oxidizer in the presence of a sulfur dye or sulfurized vat dye. In one embodiment, the method comprises treating; sulfide contaminated water by contacting the contaminated water with a gas including oxygen in the presence of a sulfur dye or a sulfurized vat dye. The method is useful for remediating industrial, agricultural, and municipal wastewater.

A method for removing sulfides from an aqueous liquid, wherein the aqueous liquid is contacted with an oxidizer in the presence of fibrous material dyed with at least one sulfur dye or sulfurized vat dye, to convert the sulfides in the aqueous liquid to a non-toxic product.

A method for removing sulfides from an aqueous liquid, wherein the aqueous liquid is contacted with an oxidizer in the presence of fibrous material dyed with at least one sulfur dye or sulfurized vat dye, to convert the sulfides in the aqueous liquid to a non-toxic product.

A method of treating fly ash containing sodium sulfate from a recovery boiler of a chemical pulp mill. This method includes at least the following steps: a) ash is dissolved in an aqueous solution and the pH of the solution is adjusted with alkali for precipitating impurities, b) the solution is filtered for removing the impurities containing precipitate, c) sodium sulfate is crystallized from the solution and the crystals are separated from the solution by filtering or by centrifugation, and d) the crystallized sodium sulfate is used as initial material for producing sodium and sulfur containing chemicals or as process chemical.

A method for treating sulfide in an aqueous fluid comprises contacting the fluid with an oxidizer in the presence of a sulfur dye or sulfurized vat dye. In one embodiment, the method comprises treating sulfide contaminated water by contacting the contaminated water with a gas including oxygen in the presence of a sulfur dye or a sulfurized vat dye. The method is useful for remediating industrial, agricultural, and municipal wastewater.

A method for treating sulfide in an aqueous fluid comprises contacting the fluid with an oxidizer in the presence of a sulfur dye or sulfurized vat dye. In one embodiment, the method comprises treating sulfide contaminated water by contacting the contaminated water with a gas including oxygen in the presence of a sulfur dye or a sulfurized vat dye. The method is useful for remediating industrial, agricultural, and municipal wastewater.

A method for removing hydrogen sulfide from a biogas, wherein the hydrogen sulfide is absorbed in an aqueous liquid to produce a cleaned gas having a reduced amount of hydrogen sulfide relative to the biogas. The aqueous liquid is subsequently treated by contacting with a sulfur dye or sulfurized vat dye in the presence of an oxidizer such as oxygen gas, to convert the sulfides in the aqueous liquid to a non-toxic, water-soluble, product.