# US 8,273,382 B2 · Suppressing microbial growth in pulp and paper > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,273,382 B2 - Document ID: US8273382B2 - Status: Granted - Kind: B2 - Application number: 12/689,742 - Filed: 2010-01-19 - Published: 2010-05-13 - Granted: 2012-09-25 - Earliest claimed: 2006-01-27 - Assignees: Nalco Company - Inventors: Laura E. Rice; Andrew J. Cooper; Robert L. Wetegrove; Michael V. Enzien - Web page: https://patentgrep.com/patent/US8273382B2 ## CPC - C02F 1/76: with halogens or compounds of halogens {(C02F1/4674 takes precedence)} - A01N 59/00: Biocides, pest repellants or attractants, or plant growth regulators containing elements or inorganic compounds - C02F 2103/28: from the paper or cellulose industry - C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes) - A01N: PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF (preservation of food or foodstuff A23); BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES (preparations for medical, dental or toiletry purposes which kill or prevent the growth or proliferation of unwanted organisms A61K); PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS ## Abstract A composition for anti-microbial effect in a water system such as a pulp and paper processing line with an aqueous slurry. The composition comprises a free chlorine-generating biocide comprising a chlorine source, urea, and an alkali in a concentration sufficient to provide a pH greater than 10, and typically at least pH 11. ## Claims ### Claim 1 A method for stabilizing chlorine for use as a water treatment biocide in a papermaking process system, comprising the steps of: adding, with mixing, a free chlorine source to a point in a stream of the papermaking process system; adding, with mixing, urea to a point in the stream of the papermaking process system; and adding, with mixing, an alkali to a point in the stream of the papermaking process system, to cause mixing of the alkali with the chlorine source and the urea; wherein the result of the additions causes to be formed for a period of time within the papermaking process stream a composition, the composition comprising: a free chlorine-generating biocide comprising a chlorine source; urea; and an alkali in a concentration sufficient to provide a pH of from 12 to 13.5 for said composition, and wherein the composition does not comprise stabilized bromine. ### Claim 2 (depends on 1) The method of claim 1 in which the chlorine source, the urea, and the alkali are all added to points in the stream of the process system which are the same or adjacent to each other. ### Claim 3 (depends on 1) The method of claim 1 in which the chlorine source and the alkali are premixed and added to the stream of the process system together, and the urea is separately added to the stream of the process system. ### Claim 4 (depends on 1) The method of claim 1 in which the chlorine source, the urea, and the alkali are all separately added to the stream of the process system. ### Claim 5 (depends on 4) The method of claim 4 in which the free chlorine source is added to the stream of the paper process system intermittently, and the urea and the alkali are added continuously. ### Claim 6 (depends on 1) The method of claim 1 in which said chlorine source comprises an aqueous solution of sodium hypochlorite having approximately 5-15 weight percent of chlorine (based on Cl2) plus sufficient sodium hydroxide to provide a pH of at least 11 in the zone of mixing with urea. ### Claim 7 (depends on 1) The method of claim 1 in which said urea comprises an aqueous urea solution, in a concentration within about 20% of the solubility limit for urea in the solution at the temperature at which solution is used. ### Claim 8 (depends on 1) The method of claim 1 in which the chlorine source and the urea used are present in a molar ratio of 2:1-1:2, the chlorine being calculated as Cl2. ### Claim 9 (depends on 1) The method of claim 1 in which said chlorine source is present in a concentration sufficient to provide essentially an equimolar amount of chlorine, expressed as Cl2, to the urea present. ### Claim 10 (depends on 1) The method of claim 1 in which said chlorine source is selected from the group consisting of: calcium hypochlorite; sodium hypochlorite; dichloroisocyanurate; trichloroisocyanurate; dichlorohydantoin; and Cl2. ### Claim 11 (depends on 1) The method of claim 1 in which said alkali comprises sodium hydroxide or potassium hydroxide. ### Claim 12 (depends on 1) The method of claim 1 in which the chlorine source is added to the stream of the paper process system intermittently, and the urea and the alkali are added to the process stream intermittently. ### Claim 13 (depends on 1) The method of claim 1 in which the free chlorine source is added to the stream of the paper process system continuously, while the urea and the alkali are added continuously. ### Claim 14 (depends on 1) The method of claim 1 in which the free chlorine source is added to the stream of the paper process system continuously, and the urea and the alkali are added intermittently.