Reference
P. Steenbeek, A. Harrison, P. Sisk - As presented at African Pulp & Paper Week 17th - 19th October 2000
Abstract
Historically organic non oxidising biocides have been used to control microbiological growth and its adverse effects in paper manufacture. This paper explains the chemistry and presents successful case histories describing the use of Bromo-Chloro-5,5-Dimethylhydantoin (BCDMH) a solid bromine releasing oxidising biocide, to control slime build-up in paper manufacture process waters. BCDMH has many advantages and benefits over traditional non oxidising biocides particularly in alkaline waters high in organics and nitrogen compounds, and in systems that are moving to further closure of water loops.
In the scope of the ever increasing regulatory scrutiny paper manufacturers all over the world are experiencing, the environmental fate of the reaction- and breakdown products will be explained. Working showing that BCDMH does not lead to increased discharges of rest AOX will be reported.
BCDMH offers the paper manufacturer a unique solution to microbiological problems by overcoming the disadvantages of traditional non oxidising biocides. The paper will present some specific efficacy data towards filamentous bacteria, typically found in paper machine fresh water and slime deposits. Data will be presented that demonstrate that Hypobromous acid from BCDMH is compatible with polyamide fibre (used in the machine clothing), whereas hypochlorous acid attacks the PA fibres.
Conclusion
Whilst most chemical products are feeling the pressure of increasing regulatory, environmentally and operational scrutiny in the Paper industry, BCDMH is gaining more and more credit as a unique, safe, and cost effective micro biocides, fully compatibly with the conditions found in modern paper manufacturing practices. The product is proven to be 3 times more effective towards filamentous bacteria (routinely found in paper machine fresh water and slime deposits), than NaOCl, whilst it's use as a slimicide does also not reduce the lifetime of the polyamide based paper machine clothing.
In a typical case where BCDMH was used in a paperboard mill, the AOX compounds formed demonstrated the same rate of bio-degradability, as the background AOX being released from this plant. This again confirms that the use of BCDMH in paper manufacture does not create any extra environmental concerns with regards to AOX release, when switching from conventional non-oxidising biocide to the oxidiser BCDMH. Many paper makers all markets in the world have learned to appreciate these benefits and use them in their favour, which help them to create sustainable competitive advantages compared to competitors. The BCDMH product forms enable paper makers to obtain increasing operational 'peace of mind' and runnability improvements. As BCDMH is one of the best supported water treatment biocides around these days, users can expect more and more knowledge to become available about the chemical and it's performance in the many unit operations found in Paper manufacture.