Problem Summary

Deposition in the wet end of a paper machine is typically composed of microorganisms and organic and inorganic contaminants.  The microbiological content of such deposits can be caused by any or all of three distinct classes of microorganisms: bacteria, fungi, and fresh water microorganisms.  These microorganisms entrap fillers, fibers, and naturally occurring inorganic contaminants, forming deposits.  When these deposits slough off they can cause a variety of production and quality problems such as holes, spots, and breaks and can increase the frequency of required boilouts and wash-ups.

Strong oxidizing biocides, such as bleach, chlorine dioxide, and hypobromous acid, are commonly used to control microorganisms in alkaline papermaking systems.  However, paper streams contain many substances that consume oxidizers (e.g., fiber and starch).  Therefore, to achieve effective microbiological control, the oxidizer must be overdosed to overcome the effect of these substances.  When dosed in this manner, the oxidizer can cause many unwanted reactions and adverse side effects, including consumption of costly wet end additives, increased corrosion rates, and reduced felt life.

Recommended Solution

Spectrum® Ammonium Bromide Technology is a new, patented biocide that effectively controls microorganisms in alkaline papermaking systems without the adverse side effects associated with strong oxidizing biocides.  The biocide, which is produced onsite by blending ammonium bromide, sodium hypochlorite, and mill fresh water, can be applied in a continuous or intermittent fashion, depending on the specific system.  Because the biocide does not react with fiber, it can be added not only to white water systems but also to thick stock, such as broke and recycled fiber.

Key benefits recorded from practical applications of Spectrum® Ammonium Bromide Technology include:

Reduced sheet breaks
Reduced sheet defects
Increased time between boilouts
Reduced washups
Reduced corrosion rates
Reduced consumption of costly wet end additives
Reduced felt degradation
Reduced halogenated organic compounds
Reduced biocide usage, which keeps program costs affordable
No negative effect on activated sludge plants (even at addition rates 10 times higher than recommended)