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 the consumption of costly wet end additives, increased corrosion rates, and reduced felt life.

Spectrum® Ammonium Bromide Technology is a new, patented biocide that effectively controls microorganisms in alkaline systems without the adverse side effects associated with strong oxidizing biocides.  The new biocide, which quickly degrades into inert compounds before effluent discharge, is produced onsite by blending an ammonium bromide solution with sodium hypochlorite and mill fresh water.  Dedicated blending and dosing equipment ensures safe, consistent production of the biocide at the mill site.

Spectrum® Ammonium Bromide Technology is generally available in the United States, Europe, Asia-Pacific, and Latin America.  At this time, the technology is pending state registration in California and PMRA registration in Canada.

Mode of Action

Figure 1 shows the five stages of biofilm formation on a paper machine surface.  Spectrum® Ammonium Bromide Technology works in Stage 2 by killing planktonic microorganisms before they have an opportunity to attach to the paper machine surface.  By hindering bacterial attachment in Stage 2, the subsequent formation of biofilm in Stages 3-5 is prevented.  This mode of action has been validated in both the lab and in commercial applications.

Application Technology

Spectrum® Ammonium Bromide Technology can be applied to any alkaline system in a continuous or intermittent fashion, depending on the specific system.  Also, since 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.  The dosage required depends on several factors, including fresh water usage, water recycle, and presence of reducing agents.

Onsite Production Process

Spectrum® Ammonium Bromide Technology is produced onsite using proprietary dosing equipment.  The dosing equipment blends the ammonium bromide solution with sodium hypochlorite and mill fresh water in the correct stoichiometric ratio under the required reaction conditions to assure 100% conversion of the components.  The dosing equipment also strictly controls the reaction to ensure that only the novel biocide is produced.

Recorded Benefits

The following benefits have been recorded from practical applications of Spectrum® Ammonium Bromide Technology.  Not all benefits are realized for all applications.

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)