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: The present invention relates to a method for recovering crude tall oil from a soap which method comprises the steps of: determining a correlation between the crude tall oil content and the water content of the soap, determining an amount of acid and water needed in order to separate an optimal amount of crude tall oil from the soap dependent on the crude tall oil content of the soap, measuring the water content of the soap, adding the optimal amount of acid and water to the soap, mixing the added acid and water with the soap whereby an acidulated soap is formed and the crude tall oil is separated and recovering the separated crude tall oil from the acidulated soap.

Abstract: The present invention relates to a method for recovering crude tall oil from a soap which method comprises the steps of: determining a correlation between the crude tall oil content and the water content of the soap, determining an amount of acid and water needed in order to separate an optimal amount of crude tall oil from the soap dependent on the crude tall oil content of the soap, measuring the water content of the soap, adding the optimal amount of acid and water to the soap, mixing the added acid and water with the soap whereby an acidulated soap is formed and the crude tall oil is separated and recovering the separated crude tall oil from the acidulated soap.

Abstract: According to the invention, polysulfide is used in the manufacture of kraft pulp in the initial stage of a displacement batch process in order to improve the yield. Polysulfide-containing white liquor is added inter-mixed with the first liquor charged to the digester, or as a separate charge before the impregnation liquor is introduced. Preferably, a cooking catalyst, e.g. antraquinone, is added to the white liquor charge as the cooking stage commences.