METHOD FOR INCREASING BIOAVAILABILITY OF SULPHITE LIQUORS CONTAINING LIGNOSULPHONATES, FORMED WHEN PRODUCING CELLULOSE Russian patent published in 2025 - IPC C02F1/72 C08J11/00 C12N1/24 D21C11/00 

FIELD: chemical or physical processes.

SUBSTANCE: invention relates to processing of sulphite liquors containing lignosulphonates, formed in pulp and paper industry. Method of increasing the bioavailability of sulphite liquors containing lignosulphonates, formed during the production of cellulose, involves dilution of alkali with waste water from washing cellulose in ratio of 1:5–1:10, which are pre-acidified with 10% hydrochloric acid solution to pH 3–3.5. Method then includes treatment with Fenton reagent at weight ratio H₂O₂/Fe²⁺ from 2 to 6 and dose of hydrogen peroxide—1.0–4.0 g/dm³, dose of Fe²⁺ ions—0.2–1.0 g/dm³ or 1.0–5.0 g/dm³ of iron sulphate, wherein processing is carried out in static mode at temperature of 18–20 °C for 1–3 hours until the ratio of BOC₅/COC 0.28–0.45 (biological oxygen consumption/chemical oxygen consumption).

EFFECT: proposed method of increasing bioavailability of sulphite liquors reduces load on treatment facilities in pulp and paper production as a result of their partial destruction with formation of easily oxidized compounds.

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