Abstract: The present invention relates to a process for the controlling the sodium and sulfur levels in a pulp mill, comprising the steps of: a) providing a pulp mill stream comprising sulfide and having a total alkali concentration of at least 2 Molar; b) supplying a portion of the pulp mill stream to a reactor comprising sulfide oxidizing bacteria and removing sulfide from the pulp mill stream by subjecting said stream to sulfide oxidizing bacteria in the presence of oxygen, and at a pH in the range 8 to 11, to oxidize the sulfide to elemental sulfur, c) withdrawing from the reactor a treated pulp mill stream comprising sulfur, wherein the portion of the pulp mill stream is mixed with a portion of the sulfide oxidizing bacteria present in the reactor prior to supplying the pulp mill stream to the reactor in step b).

Abstract: The present invention relates to a process for the treatment of industrial alkaline streams comprising sulfide and carbonate, comprising the steps of: a) providing an industrial alkaline stream comprising sulfide and carbonate; b) supplying the industrial alkaline stream to a bioreactor comprising sulfide oxidizing bacteria and removing sulfide from the industrial alkaline stream by subjecting said stream to sulfide oxidizing bacteria in the presence of oxygen, and supplying a pH adjustment agent to the bioreactor to maintain a pH in the range in the range 8 to 11, to oxidize the sulfide to elemental sulfur, c) withdrawing from the bioreactor a treated industrial alkaline stream comprising elemental sulfur, wherein a portion of the sulfide oxidizing bacteria is removed from the bioreactor and mixed with the industrial alkaline stream prior to supplying the industrial alkaline stream to the bioreactor in step b).

Abstract: A process for removing sulphide from an aqueous solution comprising sulphide is disclosed, in which the aqueous solution is subjected to sulphide-oxidizing bacteria in the presence of oxygen in a reactor to oxidize sulphide to elemental sulphur. According to the process, a molecular-oxygen containing gas is supplied to a reactor containing the sulphide-oxidizing bacteria in an aqueous medium, such that one or more aerated zones and one or more non-aerated zones are created in the aqueous medium with upward liquid flow in the aerated zones and downward liquid flow in the non-aerated zones; and a feed stream of the aqueous solution comprising sulphide is injected into the reactor in the one or more non-aerated zones, wherein the one or more aerated zone(s) are not separated from the one or more non-aerated zone(s) by means of vertically extending reactor internal.

Abstract: Hydrogen sulfide can be removed from a liquid effluent of an anaerobic reactor, by subsequently: —contacting the effluent liquid in counter current with a treated product gas of the anaerobic reactor to absorb hydrogen sulfide in the gas, —collecting the desulfurized effluent liquid after said contacting, —discharging at least part of the collected desulfurized effluent recirculation liquid as a treated effluent. To a remaining part of the desulfurized effluent waste water can be added and mixed, and the mixed water can be fed to the anaerobic reactor. Spent gas of the contacting step can be combined with sulfide-containing product gas of the anaerobic reactor and treated by desulfurization.

Abstract: A process for removing sulphide from an aqueous solution comprising sulphide is disclosed, in which the aqueous solution is subjected to sulphide-oxidising bacteria in the presence of oxygen in a reactor to oxidise sulphide to elemental sulphur. According to the process, a molecular-oxygen containing gas is supplied to a reactor containing the sulphide-oxidising bacteria in an aqueous medium, such that one or more aerated zones and one or more non-aerated zones are created in the aqueous medium with upward liquid flow in the aerated zones and downward liquid flow in the non-aerated zones; and a feed stream of the aqueous solution comprising sulphide is injected into the reactor in the one or more non-aerated zones, wherein the one or more aerated zone(s) are not separated from the one or more non-aerated zone(s) by means of vertically extending reactor internal.

Abstract: Hydrogen sulfide can be removed from a liquid effluent of an anaerobic reactor, by subsequently: —contacting the effluent liquid in counter current with a treated product gas of the anaerobic reactor to absorb hydrogen sulfide in the gas, —collecting the desulfurised effluent liquid after said contacting, —discharging at least part of the collected desulfurised effluent recirculation liquid as a treated effluent. To a remaining part of the desulfurised effluent waste water can be added and mixed, and the mixed water can be fed to the anaerobic reactor. Spent gas of the contacting step can be combined with sulfide-containing product gas of the anaerobic reactor and treated by desulfurisation.

Abstract: Alkaline solutions resulting from extracting sulfide from hydrocarbon fluids can be treated in a combination of one or more electrodialysis cells and a bioreactor. The electrodialysis cell (2) includes an anode (4), a cathode (5), an electric power supply (7) and a first (12) and a second (11) compartment separated from each other by an anion exchange membrane (9). The alkaline solution is fed into the first compartment at the cathode side and the diluate (sulfide-depleted stream) leaving the first compartment has a lowered sulfide content and can be reused as the alkaline extractant solution. The concentrate (sulfide-enriched stream) leaving the second compartment is treated in the bioreactor (3) for removing sulfide and is then returned.

Abstract: Alkaline solutions resulting from extracting sulfide from hydrocarbon fluids can be treated in a combination of one or more electrodialysis cells and a bioreactor. The electrodialysis cell (2) includes an anode (4), a cathode (5), an electric power supply (7) and a first (12) and a second (11) compartment separated from each other by an anion exchange membrane (9). The alkaline solution is fed into the first compartment at the cathode side and the diluate (sulfide-depleted stream) leaving the first compartment has a lowered sulfide content and can be reused as the alkaline extractant solution. The concentrate (sulfide-enriched stream) leaving the second compartment is treated in the bioreactor (3) for removing sulfide and is then returned.