A method of generating electricity in a body of water includes providing a colony of sulfur-reducing bacteria, a colony of sulfur-oxidizing bacteria, and a colony of denitrifying bacteria submerged in the body of water. The colony of sulfur-reducing bacteria can be used to convert at least a portion of sulfates present in the body of water to hydrogen sulfide. The colony of sulfur-oxidizing bacteria can be used to convert the hydrogen sulfide to sulfuric acid, which can react with manganese to produce hydrogen gas. The colony of denitrifying bacteria can be used to convert at least a portion of nitrogen oxides in the body of water to nitrogen gas, which can be bubbled through a portion of water from the body of water to remove dissolved oxygen gas. The hydrogen gas and oxygen gas can be combined in a fuel cell generator to generate electricity.

A method of generating electricity in a body of water includes providing a colony of sulfur-reducing bacteria, a colony of sulfur-oxidizing bacteria, and a colony of denitrifying bacteria submerged in the body of water. The colony of sulfur-reducing bacteria can be used to convert at least a portion of sulfates present in the body of water to hydrogen sulfide. The colony of sulfur-oxidizing bacteria can be used to convert the hydrogen sulfide to sulfuric acid, which can react with manganese to produce hydrogen gas. The colony of denitrifying bacteria can be used to convert at least a portion of nitrogen oxides in the body of water to nitrogen gas, which can be bubbled through a portion of water from the body of water to remove dissolved oxygen gas. The hydrogen gas and oxygen gas can be combined in a fuel cell generator to generate electricity.

A method can include performing a series of reactions in a closed cycle, the series of reactions consisting of a hydrolysis reaction where a redox reagent is oxidized to a corresponding oxidized redox reagent with water contemporaneously with the production of hydrogen; and a reduction reaction where the oxidized redox reagent is reduced to the redox reagent using a sulfurous reactant contemporaneously with production of sulfur dioxide.

A method can include performing a series of reactions in a closed cycle, the series of reactions consisting of a hydrolysis reaction where a redox reagent is oxidized to a corresponding oxidized redox reagent with water contemporaneously with the production of hydrogen; and a reduction reaction where the oxidized redox reagent is reduced to the redox reagent using a sulfurous reactant contemporaneously with production of sulfur dioxide.

Disclosed are methods and systems for capturing carbon dioxide and utilizing calcium sulfate to generate useful products.

A method of generating hydrogen gas includes providing a colony of sulfur-reducing bacteria and a colony of sulfur-oxidizing bacteria. The colonies can be submerged in a body of water. The colony of sulfur-reducing bacteria can be used to convert at least a portion of sulfates present in the body of water to hydrogen sulfide. The colony of sulfur-oxidizing bacteria can be used to convert the hydrogen sulfide to sulfuric acid. The sulfuric acid can react with manganese to produce hydrogen gas and manganese sulfate.

A method of generating hydrogen gas includes providing a colony of sulfur-reducing bacteria and a colony of sulfur-oxidizing bacteria. The colonies can be submerged in a body of water. The colony of sulfur-reducing bacteria can be used to convert at least a portion of sulfates present in the body of water to hydrogen sulfide. The colony of sulfur-oxidizing bacteria can be used to convert the hydrogen sulfide to sulfuric acid. The sulfuric acid can react with manganese to produce hydrogen gas and manganese sulfate.

A process may involve digesting raw phosphate with concentrated sulfuric acid and converting the raw phosphate to calcium sulfate in the form of dihydrate and/or hemihydrate, and phosphoric acid, separating off calcium sulfate as solid from a liquid phase of a suspension that is obtained, treating the calcium sulfate that is separated off or from a stockpile with an acid to give a suspension with purified calcium sulfate and P.sub.2O.sub.5-containing acid solution, separating off the purified calcium sulfate as solid from a liquid phase of a suspension obtained, using the P.sub.2O.sub.5-containing liquid phase as a portion of the sulfuric acid required for digesting the raw phosphate or as feedstock for treating phosphogypsum from the stockpile to give a suspension of purified calcium sulfate and P.sub.2O.sub.5-containing acid solution, which is thereafter processed.

A process may involve digesting raw phosphate with concentrated sulfuric acid and converting the raw phosphate to calcium sulfate in the form of dihydrate and/or hemihydrate, and phosphoric acid, separating off calcium sulfate as solid from a liquid phase of a suspension that is obtained, treating the calcium sulfate that is separated off or from a stockpile with an acid to give a suspension with purified calcium sulfate and P.sub.2O.sub.5-containing acid solution, separating off the purified calcium sulfate as solid from a liquid phase of a suspension obtained, using the P.sub.2O.sub.5-containing liquid phase as a portion of the sulfuric acid required for digesting the raw phosphate or as feedstock for treating phosphogypsum from the stockpile to give a suspension of purified calcium sulfate and P.sub.2O.sub.5-containing acid solution, which is thereafter processed.

The present disclosure provides a desulfurization and sulfur recovery method for sulfur dioxide flue gas, and belongs to the technical field of non-ferrous metal smelting. The method includes the following steps: desulfurizing the sulfur dioxide flue gas by taking slagging flux limestone or quicklime for smelting or converting process as a desulfurizer, and adsorbing SO.sub.2 in the gas to obtain gypsum residue, calcium sulfite, and the desulfurized flue gas, where SO.sub.2 in the sulfur dioxide flue gas before desulfurization is less than 1 vol %; and recycling the gypsum residue and the calcium sulfite to the smelting or converting furnace for slagging, resolving the SO.sub.2 into smelting off-gas, producing sulfuric acid in acid plant.