Lonza Inc.

Michael Leonid Ludensky

Philip Gerdon Sweeny

Daniel Wayne Lemke

Kevin E Janak

Sarah Elizabeth Kopecky

Disclosed are compositions for stabilizing a source of active halogen in aqueous solution. The compositions comprise (i) at least one substituted N-hydrogen compound, such as 5,5-dimethylhydantoin, and (ii) at least one additional nitrogen compound selected from ammonia, ammonium salts, and nitrogen compounds containing no carbon-hydrogen bonds, the molar ratio of (i) and (ii) being in the range of 50:1 to 0.02:1. Active halogen-containing aqueous solutions stabilized by the above compositions are particularly useful for controlling microbial and planktonic growth in aqueous systems such as process liquids in the pulping or papermaking industry. The compositions are also useful in reducing the corrosivity of halogen-containing solutions.

Stabilized active halogen solutions

The present invention provides a method for the removal of biofilm, flocculent bulked sludge or bulked biologically active sludge from an aqueous system. The method involves adding one or more chlorinated hydantoins, such as dichloro- or monochlorodialkylhydantoin, to the aqueous system. Alternatively, the chlorinated hydantoin may be formed in situ by adding a chlorine source and an alkylated hydantoin separately to the aqueous system. The invention is particularly advantageous because of the outstanding photostability of the chlorinated hydantoin solutions even when exposed to sunlight.

Method for removal of biofilm

The inventors have discovered that partially halogenated hydantoins exhibit superior antimicrobial efficacy and decreased performance additive decomposition rates than fully halogenated hydantoins, such as dichlorodimethyl hydantoin (DCDMH). Partially halogenated hydantoins are solutions containing monochlorohydantoin and, optionally, dihalogenated hydantoin or non-halogenated hydantoin. The present invention is a method of reducing slime in a circulating water slurry comprising organic matter and one or more performance additives, such as optical brighteners, while minimizing decomposition of the performance additives. The method comprises adding one or more partially halogenated hydantoins, such as Cl -chlorodimethyl hydantoin, to the slurry. The concentration of partially halogenated hydantoin maintained in the slurry generally ranges from about 0.01 to about 50 ppm (expressed as Cl ). This method is particularly useful for circulating water slurries in paper processing.

Growing community of inventors

Randolph, NJ, United States of America

Michael Leonid Ludensky